{"gene":"CCR8","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":1997,"finding":"CCR8 was identified as the specific receptor for the human CC chemokine I-309 (CCL1). Transfection of the CY6/TER1/CKR-L1 open reading frame into mouse pre-B cells conferred calcium flux and chemotaxis in response to I-309 (EC50 ~2 nM), while 20 other chemokines were inactive. Signaling was sensitive to pertussis toxin, indicating coupling to a Gi-type G protein.","method":"Receptor transfection into pre-B cells, calcium flux assay, chemotaxis assay, pertussis toxin inhibition, 125I-I-309 binding (Kd ~1.2 nM)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with functional assays; independently replicated in same year by Tiffany et al.","pmids":["9211859"],"is_preprint":false},{"year":1997,"finding":"CCR8 is constitutively expressed in monocytes and thymus, functions as a monocyte chemoattractant receptor for I-309, and inhibits apoptosis in thymic cell lines. Signaling is pertussis toxin-sensitive, confirming Gi coupling.","method":"Transfection, calcium flux, chemotaxis, pertussis toxin inhibition, northern blot for tissue expression","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1 — reconstitution in transfected cells with multiple functional readouts, replicated across labs","pmids":["9207005"],"is_preprint":false},{"year":1998,"finding":"CCR8 is preferentially expressed on polarized Th2 cells (both human and mouse) and not Th1 cells. The CCR8 ligands I-309 and TCA-3 act as potent chemoattractants specifically for Th2-polarized cells.","method":"Northern blot, RT-PCR, chemotaxis assay with polarized T cell subsets, mouse CCR8 cloning","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods, replicated across human and mouse systems by multiple labs","pmids":["9670926"],"is_preprint":false},{"year":1998,"finding":"CCR8 expression on Th2 cells is transiently upregulated following TCR and CD28 engagement, and this upregulation is IL-4-independent. Upregulation enhances functional chemotactic responses to I-309 and TARC.","method":"Flow cytometry, chemotaxis assay, cytokine neutralization","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2 — clean functional experiment with cytokine blockade, single lab","pmids":["9820476"],"is_preprint":false},{"year":1998,"finding":"TARC (CCL17) and MIP-1β (CCL4) were identified as additional functional CCR8 ligands, inducing chemotaxis in CCR8-transfected Jurkat cells.","method":"Stable transfection of CCR8 into Jurkat cells, chemotaxis assay","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — functional assay in transfected cells, single lab; later studies suggest primary ligand is CCL1","pmids":["9521068"],"is_preprint":false},{"year":1998,"finding":"CCR8 serves as a co-receptor for HIV-1 infection; diverse T-cell tropic, dual-tropic, and macrophage-tropic HIV-1 strains can use CCR8, and I-309 (CCL1) potently inhibits HIV-1 envelope-mediated cell-cell fusion and virus infection through CCR8.","method":"Cell-cell fusion assay, virus infection assay, calcium flux, flow cytometry, pertussis toxin inhibition","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — multiple functional assays, replicated by multiple labs (Jinno et al. 1998, Lee et al. 2000, Calado et al. 2010)","pmids":["9417093"],"is_preprint":false},{"year":1998,"finding":"TER1/CCR8 is expressed in brain-derived CD4+ cells and T cells and functions as a co-receptor for brain-cell-tropic HIV-1 variants that are resistant to M-tropic and T-tropic strains.","method":"Degenerate PCR, expression of TER1 in CD4+ resistant cells, infection assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — direct infection assay establishing CCR8 as functional co-receptor in brain-derived cells, single lab","pmids":["9480837"],"is_preprint":false},{"year":1999,"finding":"HHV-8-encoded vMIP-I selectively binds to and signals through CCR8 as an agonist (inducing Ca2+ flux in T cells), while vMIP-II and vMCC-I act as CCR8 antagonists. A comprehensive ligand binding fingerprint for CCR8 identified four high-affinity ligands (vMIP-I, vMIP-II, vMCC-I, and human I-309).","method":"Competitive radioligand binding with 65 chemokines, calcium mobilization assay in human T cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — comprehensive in vitro pharmacological characterization with multiple orthogonal assays, replicated by Endres et al. 1999","pmids":["10419462"],"is_preprint":false},{"year":1999,"finding":"vMIP-I (KSHV-encoded) is a specific agonist for CCR8: it binds with high affinity, induces calcium flux, and drives chemotaxis in CCR8-transfected Y3 cells. vMIP-I does not interact with CCR5 or 11 other receptors tested.","method":"Calcium flux assay, chemotaxis assay, competition binding in CCR8-transfected cells","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1 — reconstitution in transfected cells with multiple functional assays, consistent with Dairaghi et al.","pmids":["10377196"],"is_preprint":false},{"year":2000,"finding":"The molluscum contagiosum poxvirus-encoded MC148 is a highly selective CCR8 antagonist that binds with high affinity only to CCR8 among 16 chemokine receptors and blocks I-309/CCR8-induced calcium mobilization and chemotaxis without affecting other chemokine receptors.","method":"Competitive binding with radiolabeled chemokines, calcium mobilization assay, chemotaxis assay across 16 receptors","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1 — comprehensive pharmacological profiling across 16 receptors, confirmed antagonism with functional readouts","pmids":["10620615"],"is_preprint":false},{"year":2000,"finding":"CCR8 is expressed on human thymocytes (both immature and mature) and functions as an HIV-1 co-receptor: I-309 inhibits fusion of thymocytes with HIV-1 X4 or X4R5 envelope-expressing cells and partially inhibits productive HIV-1 infection.","method":"125I-I-309 binding on primary thymocytes, cell-cell fusion assay, productive infection assay","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 1 — direct binding and functional infection assays on primary human cells","pmids":["10888633"],"is_preprint":false},{"year":2001,"finding":"CCR8 is expressed on human vascular endothelial cells (HUVECs) and mediates endothelial cell chemotaxis in response to I-309 and vMIP-I. Pertussis toxin and anti-CCR8 antibody blocked this chemotaxis, confirming G protein-coupled, CCR8-dependent signaling in endothelial cells.","method":"Chemotaxis assay, antibody neutralization, pertussis toxin inhibition, RNA blot, immunohistochemistry","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal inhibitory approaches in a novel cell type, single lab","pmids":["11133740"],"is_preprint":false},{"year":2001,"finding":"CCR8 and CCR4 are specifically expressed on human CD4+CD25+ regulatory T cells (Tregs), which vigorously respond to CCR8 ligands CCL1 and CCL22. CCR4 ligands (CCL17, CCL22) secreted by mature dendritic cells preferentially attract Treg cells, and the migrated CCR8/CCR4-expressing population shows reduced alloproliferative response.","method":"Flow cytometry, chemotaxis assay with sorted CD4+CD25+ vs CD4+CD25- T cells, functional alloproliferation assay","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — multiple methods establishing CCR8 as specific marker and functional receptor on Tregs, highly cited and replicated","pmids":["11560999"],"is_preprint":false},{"year":2003,"finding":"CCR8 mediates human vascular smooth muscle cell (VSMC) chemotaxis in response to CCL1 and vCCL1, and this is blocked by anti-CCR8 antibody and pertussis toxin. CCR8 activation by CCL1 also induces pro-MMP-2 mRNA and protein secretion, which contributes to VSMC migration, as shown by MMP-2 antibody inhibition.","method":"Chemotaxis assay, antibody/pertussis toxin inhibition, RT-PCR, MMP-2 ELISA/western blot, poxvirus MC148 blockade","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 — multiple mechanistic readouts with specific blockers, single lab","pmids":["14576057"],"is_preprint":false},{"year":2003,"finding":"CCR8-dependent activation of the RAS/MAPK (ERK1/2) pathway mediates anti-apoptotic activity of CCL1 and vMIP-I in thymic lymphoma cells. This was demonstrated using pertussis toxin, the MEK inhibitor PD98059, a dominant negative M-RAS, and the CCR8 antagonist MC148.","method":"Apoptosis assay, pertussis toxin inhibition, ERK phosphorylation assay, MEK inhibitor (PD98059), dominant negative M-RAS, MC148 antagonist, CCR8-transfected CHO cells","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1 — multiple pharmacological and genetic tools establish CCR8→RAS/MAPK→anti-apoptosis pathway","pmids":["12645948"],"is_preprint":false},{"year":2003,"finding":"CCR8 mediates rescue of thymic lymphoma cells and murine thymocytes from dexamethasone-induced apoptosis via an ERK-dependent pathway. The CCR8 antagonist MC148 specifically blocks the anti-apoptotic activity of vMIP-I and CCL1.","method":"Apoptosis assay, ERK pathway analysis, MC148 antagonist blockade, CCR8-specific agonist vMIP-1","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 — specific receptor attribution confirmed by selective antagonist, single lab","pmids":["12525579"],"is_preprint":false},{"year":2004,"finding":"Post-translational modifications of murine CCR8 regulate its activity: tyrosine sulfation at positions Y14/Y15 is critical for CCL1 binding and calcium signaling (Y14F/Y15F double mutant essentially inactive), while N-linked glycosylation at N8 and O-linked modifications at T10/T12 have minor effects on ligand binding.","method":"Site-directed mutagenesis (Tyr→Phe, Asn→Gln, Thr/Ser→Ala), flow cytometry with CCL1-Fc fusion, calcium flux assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — systematic mutagenesis with multiple functional readouts establishing structure-function relationships","pmids":["14736884"],"is_preprint":false},{"year":2005,"finding":"CCR8 is expressed on Langerhans-type dendritic cells (DCs), mast cells, and dermal endothelial cells. CCL1 recruits both T cells and Langerhans cell-like DCs, and synergizes with CXCL12 (SDF-1α) in promoting this recruitment. CCR8 is recruited from intracytoplasmic stores to the cell surface upon T cell activation.","method":"Immunofluorescence, flow cytometry, in vitro chemotaxis assay, in vitro DC differentiation, CCL1/CXCL12 synergy experiments","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2 — multiple cell types and functional assays, single lab","pmids":["15814739"],"is_preprint":false},{"year":2005,"finding":"CCR8 expression defines IL-10-producing CD4+CD25+ T cells in Th2-type granulomatous inflammation. CCR8-deficient mice showed significantly impaired IL-10 production and reduced granuloma eosinophils in a Schistosoma egg-antigen model; adoptive transfer of CCR8+/+ CD4+ T cells corrected these defects.","method":"CCR8-/- mice, adoptive transfer, cytokine mRNA quantification, BAL cell analysis","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with adoptive transfer rescue, single lab","pmids":["15699124"],"is_preprint":false},{"year":2006,"finding":"CCR8 undergoes beta-arrestin 1/2-dependent internalization upon ligand binding (CCL1 and vMIP-I), independently of Gαi signaling. NH2-terminal extension of CCL1 by a serine residue (Ser-CCL1) generates a partial agonist, indicating the NH2 terminus plays a role in binding to an intrahelical site. Glu-286 in TM helix 7 is critical for receptor surface trafficking, and CCL7 selectively antagonizes viral (but not host) chemokine activity at CCR8.","method":"Calcium flux, chemotaxis, receptor internalization assay, beta-arrestin expression, site-directed mutagenesis, CCL7 antagonism experiments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — multiple orthogonal functional assays with mutagenesis establishing mechanism of ligand binding and receptor trafficking","pmids":["17023422"],"is_preprint":false},{"year":2007,"finding":"A non-peptide CCR8 agonist (LMD-009) interacts with CCR8 through a binding pocket involving GluVII:06 (Glu286) as a critical anchor point, shared with non-peptide antagonists targeting CCR1, CCR2, and CCR5. Ala substitution of Glu286 reduced agonist potency ~1000-fold; Ala substitution of PheVI:16 (Phe254) produced a 19-fold gain-of-function. 29 mutations across 25 residues mapped the binding pocket.","method":"Site-directed mutagenesis (29 mutations), calcium flux, chemotaxis, inositol phosphate accumulation, 125I-CCL1 competitive binding","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 — systematic mutagenesis across the binding pocket with multiple functional assays","pmids":["17652183"],"is_preprint":false},{"year":2007,"finding":"CCR8 is expressed on peritoneal macrophages (PMφ) and up-regulated by inflammatory stimuli. CCL1 produced by both PMφ and peritoneal mesothelial cells (PMCs) promotes CCR8 expression (autocrine loop), drives cell aggregation, and upregulates plasminogen activator inhibitor-1. CCR8-deficient mice and anti-CCL1-treated mice exhibit significantly reduced postoperative peritoneal adhesions.","method":"CCR8-/- mice, anti-CCL1 neutralizing antibody, in vitro cell aggregation assay, RT-PCR, flow cytometry","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO and antibody blockade with in vitro mechanistic follow-up, single lab","pmids":["17404314"],"is_preprint":false},{"year":2007,"finding":"Mast cell-derived CCL1 signals through CCR8 on CD4+ T lymphocytes to orchestrate mucosal lung inflammation, airway hyperresponsiveness, and mucus hypersecretion. CCR8 deficiency or CCL1 neutralization reduced these responses to the same degree as mast cell deficiency; adenoviral CCL1 delivery to lungs of mast cell-deficient mice restored the inflammatory phenotype.","method":"CCR8-/- mice, mast cell-deficient mice, CCL1 neutralization, adenoviral CCL1 delivery, airway hyperresponsiveness measurements, BAL cytokine analysis","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic models and epistasis experiments establishing mast cell CCL1 → CCR8+ CD4+ T cell axis, single lab","pmids":["17641040"],"is_preprint":false},{"year":2007,"finding":"CCR8 expression in CD4+CD25+ Tregs recruited to the pancreas during adoptive transfer of diabetogenic T cell clones; the only chemokine detectable ex vivo was CCL1, suggesting CCL1/CCR8 interaction mediates macrophage recruitment and activation (IL-1β, TNF-α, NO production) in type 1 diabetes.","method":"Adoptive transfer model, flow cytometry, ex vivo chemokine protein detection, macrophage functional assays","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Low","confidence_rationale":"Tier 3 — correlative in vivo localization without direct mechanistic manipulation of CCR8","pmids":["17947648"],"is_preprint":false},{"year":2008,"finding":"Using adoptive transfer of CCR4-deficient or CCR8-deficient antigen-specific Th2 cells, CCR4 (not CCR8) was found to be required for efficient entry of antigen-specific Th2 cells into the lung and airways in allergic pulmonary inflammation. CCR8-deficient Th2 cells showed normal or increased accumulation in the lung.","method":"Adoptive transfer of CCR4-/- or CCR8-/- antigen-specific Th2 cells, flow cytometry, cytokine measurement, eosinophil/mucus quantification","journal":"The Journal of allergy and clinical immunology","confidence":"High","confidence_rationale":"Tier 2 — clean adoptive transfer genetic epistasis experiment with specific phenotypic readouts","pmids":["19062085"],"is_preprint":false},{"year":2011,"finding":"Mouse CCL8 is a selective CCR8 agonist (not a CCR2 agonist, unlike all other MCP chemokines). CCL8 responsiveness defined a population of CCR8-expressing inflammatory Th2 cells enriched for IL-5. CCR8- and CCL8-deficient mice showed markedly reduced eosinophilic inflammation in chronic atopic dermatitis. Adoptive transfer established CCR8 as a key regulator of Th2 cell recruitment into allergen-inflamed skin.","method":"Ccr8-/- and Ccl8-/- mice, adoptive transfer, receptor binding assays, calcium flux, atopic dermatitis mouse model, eosinophil quantification","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 — dual KO mice with adoptive transfer, multiple cell and tissue readouts, high-impact journal","pmids":["21217759"],"is_preprint":false},{"year":2012,"finding":"C-terminal clipping of CCL1 by carboxypeptidase M (CPM) augments CCR8-mediated intracellular calcium release and anti-apoptotic activity in BW5147 cells, while reducing CCL1 binding affinity to CCR8, revealing a proteolytic regulatory mechanism for the CCL1-CCR8 axis.","method":"In vitro CPM enzymatic cleavage, mass spectrometry, calcium mobilization assay, binding assay, apoptosis assay with CPM inhibitor control","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro enzymatic reconstitution with multiple functional readouts; single lab","pmids":["22479563"],"is_preprint":false},{"year":2013,"finding":"CCR8 is a functional receptor for CCL18: CCL18 induces chemotaxis and calcium flux in CCR8-transfected cells, binds CCR8 with high affinity, induces CCR8 internalization, and competes with CCL1 for CCR8 binding. CCL1 and CCL18 cross-desensitize CCR8 on transfected cells and human Th2 cells. CCR8-deficient mouse Th2 cells fail to migrate to CCL18.","method":"CCR8 transfection, chemotaxis assay, calcium flux, competitive binding, receptor internalization, cross-desensitization, Ccr8-/- mouse Th2 cell migration","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1 — multiple orthogonal methods including KO validation establishing CCL18 as CCR8 ligand","pmids":["23999500"],"is_preprint":false},{"year":2014,"finding":"CCR8 is required for LPS-triggered cytokine production (TNF-α, IL-6, IL-10) specifically in peritoneal macrophages but not bone marrow-derived macrophages. CCR8-dependent cytokine production involves cross-talk with TLR-4 signaling via JNK and NF-κB pathways. A CCR8 antagonist (R243) phenocopied CCR8 deficiency and attenuated peritoneal adhesions in vivo.","method":"CCR8-/- mice, TLR ligand stimulation, cytokine ELISA, JNK/NF-κB inhibitors, R243 CCR8 antagonist, in vivo adhesion model","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO and pharmacological antagonist with signaling pathway dissection, single lab","pmids":["24714157"],"is_preprint":false},{"year":2017,"finding":"CCL1 signaling through CCR8 on Tregs induces STAT3-dependent upregulation of FOXp3, CD39, IL-10, and granzyme B, enhancing Treg suppressive activity. CCL1 produced by Tregs at autoimmune sites creates a self-feeding autocrine loop that upregulates CCR8 on Tregs. CCR8-/- mice in adoptive transfer experiments confirmed the essential role of CCR8 in Treg-mediated suppression of EAE.","method":"Human PBMC activation assays, STAT3 inhibition, CCL1-Ig administration, CCR8-/- mouse adoptive transfer, EAE model, flow cytometry for CD39/granzyme B/IL-10","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal experiments including KO adoptive transfer and pharmacological intervention identifying specific signaling pathway","pmids":["28533380"],"is_preprint":false},{"year":2018,"finding":"CCR8 on CD301b+ dendritic cells (DCs) mediates their migration from the subcapsular sinus into the lymph node parenchyma following allergen exposure, synergizing with CCR7/CCL21 in a Src-kinase-dependent manner. CCL8 produced by CD169+SIGN-R1+ macrophages in interfollicular regions provides the CCR8 signal. In CCR8-deficient mice, CD301b+ DCs are trapped in the subcapsular sinus and cannot enter the parenchyma, resulting in defective Th2 differentiation.","method":"CCR8-/- mice, DC migration tracking by flow cytometry and imaging, CCL8 source identification, Src kinase inhibition, CCR7 expression analysis, Th2 differentiation assays","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 — CCR8-/- genetic model with mechanistic pathway (Src kinase dependence, CCL8 source identification), multiple orthogonal readouts","pmids":["30170811"],"is_preprint":false},{"year":2019,"finding":"Activated ILC2s produce CCL1 and are a major CCL1 source in vivo; CCL1 signaling via CCR8 on ILC2s regulates their proliferation and capacity to protect against helminthic infections, establishing a CCR8-dependent autocrine/paracrine feed-forward loop for ILC2 self-renewal.","method":"In vitro CCR8 chemotaxis assay, in vivo CCR8-/- mouse models, CCL1 measurement by ELISA, helminth infection model, proliferation assays","journal":"The Journal of experimental medicine","confidence":"Medium","confidence_rationale":"Tier 2 — KO mice with in vitro and in vivo functional validation, single lab","pmids":["31537642"],"is_preprint":false},{"year":2019,"finding":"CCR8 expression on Tregs was upregulated by TCR-mediated signaling in an NF-κB-dependent fashion. CCR8 was not essential for the recruitment, activation, or suppressive capacity of tumor-infiltrating Tregs per se, but ADCC-prone anti-CCR8 nanobody-Fc fusion proteins depleted ti-Tregs in an NK cell-dependent manner and elicited antitumor immunity synergizing with anti-PD-1.","method":"scRNA-seq, flow cytometry, NF-κB inhibition, nanobody generation, ADCC assay, NK cell depletion in vivo, LLC-OVA and MC38 tumor models","journal":"Journal for immunotherapy of cancer","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal experiments including mechanistic NF-κB studies, ADCC mechanism, and in vivo NK cell dependence","pmids":["33589525"],"is_preprint":false},{"year":2019,"finding":"Disruption of the CCL1-CCR8 axis (via CCL1 and Apoe double deficiency or anti-CCR8 blocking antibodies) promotes atherosclerosis by reducing Treg recruitment to the aorta, decreasing IL-10 levels, and shifting toward a Th1 response, establishing a protective role for CCL1-CCR8 in vascular inflammation.","method":"Ccl1/Apoe double-KO mice, flow chamber adhesion assay, intravital microscopy, anti-CCR8 blocking antibody, Treg quantification in aorta/spleen, cytokine measurement","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic and antibody-based approaches with multiple functional readouts, single lab","pmids":["31121182"],"is_preprint":false},{"year":2021,"finding":"CCR8 expression on tumor-infiltrating Tregs is upregulated by TCR stimulation but is not essential for their recruitment, activation, or suppressive function. Depletion of CCR8+ tumor Tregs via ADCC-capable anti-CCR8 antibody elicits antitumor immunity, reduces tumor growth, and synergizes with anti-PD-1 therapy without affecting peripheral Tregs.","method":"Fc-optimized anti-CCR8 antibody, CCR8-/- mouse tumors (MC38, B16), flow cytometry, ex vivo depletion in primary human tumor samples","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 — multiple tumor models, human ex vivo validation, mechanistic ADCC dependence demonstrated","pmids":["33757978"],"is_preprint":false},{"year":2021,"finding":"In bladder cancer, CCR8 expression in intratumoral Tregs maintains stability and potentiates suppressive function by upregulating transcription factors FOXO1 and c-MAF. CCR8 blockade destabilizes intratumoral Tregs into a fragile phenotype and reactivates antitumor immunity, augmenting anti-PD-1 benefits.","method":"Flow cytometry, ex vivo CCR8 blockade experiments, transcription factor analysis (FOXO1, c-MAF), TCGA bioinformatics, retrospective clinical cohort, anti-PD-1 combination","journal":"Cancer immunology, immunotherapy : CII","confidence":"Medium","confidence_rationale":"Tier 2 — mechanistic follow-up on FOXO1/c-MAF pathway with ex vivo functional validation, single lab","pmids":["32367308"],"is_preprint":false},{"year":2022,"finding":"CCR8+ tumor Tregs are predominantly clonally expanded cells activated by tumor-associated antigens. Anti-CCR8 mAb treatment selectively eliminated these multiclonal tumor Tregs (sparing peripheral Tregs), expanded tumor-specific CD8+ T cells, and generated memory-type antitumor immunity without autoimmunity in mice.","method":"scRNA-seq, TCR clonotype analysis, CCR8-/- mice, anti-CCR8 mAb (depleting vs. non-depleting), flow cytometry, tumor rechallenge memory assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — scRNA-seq + clonotype analysis + mAb depletion across multiple tumor types with mechanistic memory studies","pmids":["35140181"],"is_preprint":false},{"year":2022,"finding":"Donor kidney-resident macrophages upregulate CCL8 upon transplantation, which promotes CCR8-expressing recipient T cell (CD4, CD8, γδ T cell) infiltration into kidney allografts. Blocking CCL8-CCR8 or depleting donor kidney resident macrophages significantly inhibited early allograft immune infiltration and improved allograft function.","method":"Murine allogeneic kidney transplant model, CCL8/CCR8 blockade, macrophage depletion, flow cytometry for immune infiltrates, allograft function assays","journal":"Journal of the American Society of Nephrology : JASN","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo blockade and depletion experiments with functional organ outcome, single lab","pmids":["35973731"],"is_preprint":false},{"year":2022,"finding":"Intracellular lactate upregulates CCR8 expression in CD4+ T cells and macrophages through histone H3K18 lactylation at the CCR8 gene promoter, linking tumor glycolysis to CCR8-expressing immunosuppressive Tregs in glioblastoma.","method":"ChIP assay for H3K18 lactylation at CCR8 promoter, luciferase reporter assay, RT-qPCR, western blot, flow cytometry, LDHA inhibitor (oxamate)","journal":"Journal of experimental & clinical cancer research : CR","confidence":"Medium","confidence_rationale":"Tier 1-2 — ChIP with reporter assay establishes epigenetic regulatory mechanism, single lab","pmids":["37770937"],"is_preprint":false},{"year":2022,"finding":"Tumor-derived exosomes promote CCL1 secretion by lung fibroblasts, which activates CCR8 on T cells to drive Treg differentiation and establish an immunologically tolerant pre-metastatic niche. Inhibiting CCL1-CCR8 axis with AZ084 suppressed Treg differentiation and tumor metastasis in the lung.","method":"LLC-exo in vitro co-culture, CCL1 ELISA, CCR8 flow cytometry, AZ084 CCR8 antagonist, GW4869 exosome inhibitor, in vivo pre-metastatic niche mouse model","journal":"Cancer immunology, immunotherapy : CII","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological blockade with in vitro and in vivo readouts, single lab","pmids":["35428909"],"is_preprint":false},{"year":2024,"finding":"TNF-α in the colorectal cancer microenvironment upregulates CCR8 expression in Tregs via TNFR2/NF-κB signaling and the FOXP3 transcription factor. PD-1 blockade induces additional CCR8+ Treg infiltration; TNFR2 depletion or blockade suppresses tumor progression by reducing CCR8+ Treg infiltration.","method":"NF-κB/TNFR2 inhibition, FOXP3 ChIP, Tnfr2-/- mouse tumor models, anti-PD-1 combination, flow cytometry","journal":"Journal of molecular cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic and pharmacological dissection of upstream regulatory pathway, single lab","pmids":["37935468"],"is_preprint":false},{"year":2021,"finding":"Small molecule CCR8 agonists (ZK756326, AZ6, vCCL1) display biased signaling relative to human CCL1: while all induce full agonist calcium mobilization, Gβγ signaling is required for CCL1-induced but not small molecule agonist-induced cell migration. Small molecule agonists show higher efficacy for β-arrestin 1 recruitment, which occurs independently of Gαi signaling.","method":"Calcium mobilization, cellular impedance (xCELLigence), cell migration assay, β-arrestin 1/2 recruitment assay, Gβγ inhibitor (gallein), Gαi inhibitor (pertussis toxin)","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution with multiple signaling pathway inhibitors across multiple assays; single lab","pmids":["33872569"],"is_preprint":false},{"year":2025,"finding":"CCR8+ Tregs are specifically enriched in human first-trimester decidua, produced in part through CCL1 secreted by decidual CD49a+ NK cells. Depletion of CCR8+ dTregs increased fetal loss susceptibility with altered decidual immune profiles; adoptive transfer of CCR8+ Tregs rescued fetal loss in abortion-prone mice, establishing a CCR8+ Treg subset as essential for maternal-fetal tolerance.","method":"scRNA-seq, TCR sequencing, CCR8+ dTreg depletion in mice, adoptive transfer rescue experiments, CCL1 ELISA, flow cytometry","journal":"Science immunology","confidence":"High","confidence_rationale":"Tier 2 — scRNA-seq + depletion + adoptive transfer establishing causal role of CCR8+ Tregs in maternal tolerance","pmids":["40249828"],"is_preprint":false}],"current_model":"CCR8 is a Gi-coupled seven-transmembrane chemokine receptor whose primary endogenous ligand is CCL1 (I-309), with additional ligands including CCL8 and CCL18; upon ligand binding it signals through Gαi (pertussis toxin-sensitive), activates the RAS/MAPK/ERK pathway to suppress apoptosis, and recruits β-arrestins for internalization, with tyrosine sulfation at the N-terminal Y14/Y15 residues critical for CCL1 binding; CCR8 is selectively expressed on Th2 cells, a subset of CD4+CD25+FOXP3+ regulatory T cells, dendritic cell subsets, monocytes/macrophages, and thymocytes, where it directs cell trafficking and—on tumor-infiltrating Tregs whose CCR8 expression is driven by TCR/NF-κB and TNFR2/NF-κB signals—mediates potent immunosuppression that can be therapeutically targeted by ADCC-capable anti-CCR8 antibodies to selectively deplete tumor Tregs and restore antitumor immunity."},"narrative":{"teleology":[{"year":1997,"claim":"Deorphanization of CCR8 established it as the specific Gαi-coupled receptor for CCL1 (I-309), resolving the ligand identity and G-protein coupling for this orphan seven-transmembrane receptor.","evidence":"Transfection of CCR8 into pre-B cells conferred CCL1-dependent calcium flux (EC50 ~2 nM) and chemotaxis blocked by pertussis toxin; radioligand binding measured Kd ~1.2 nM","pmids":["9211859","9207005"],"confidence":"High","gaps":["No structural information on CCR8-CCL1 complex","Endogenous expression levels on primary cells not quantified"]},{"year":1998,"claim":"CCR8 was shown to be preferentially expressed on Th2-polarized T cells and to function as an HIV-1 co-receptor, defining its dual roles in adaptive immunity and viral pathogenesis.","evidence":"Northern blot/RT-PCR on polarized T cells; HIV-1 envelope-mediated fusion and infection assays in CCR8-transfected and primary thymocyte systems","pmids":["9670926","9417093","9480837","9820476"],"confidence":"High","gaps":["In vivo relevance of CCR8 for HIV-1 tropism in patients not established","Mechanism of Th2-selective expression unknown"]},{"year":1999,"claim":"Viral chemokine mimics from HHV-8 (vMIP-I as agonist, vMIP-II as antagonist) and identification of MC148 as a highly selective CCR8 antagonist provided pharmacological tools and revealed that viruses exploit or block CCR8 to modulate host immunity.","evidence":"Comprehensive competitive binding across 65 chemokines, calcium mobilization, and chemotaxis assays in transfected cells and primary T cells","pmids":["10419462","10377196","10620615"],"confidence":"High","gaps":["In vivo role of viral chemokine mimicry in HHV-8 or MCV pathogenesis not directly tested","Structural basis of vMIP-I agonism vs. MC148 antagonism unknown"]},{"year":2001,"claim":"Discovery that CCR8 marks CD4+CD25+ regulatory T cells and mediates their chemotaxis to CCL1 established the receptor as a key Treg surface marker and functional trafficking receptor.","evidence":"Flow cytometry and chemotaxis of sorted CD4+CD25+ vs CD25− T cells; functional alloproliferation assays","pmids":["11560999"],"confidence":"High","gaps":["Whether CCR8 signaling has intrinsic effects on Treg suppressive function or only on migration was unresolved","CCR8 expression heterogeneity within Treg subsets not characterized"]},{"year":2003,"claim":"CCR8 was shown to activate the RAS/MAPK/ERK pathway to suppress apoptosis, establishing a survival signaling function beyond chemotaxis.","evidence":"Pertussis toxin, MEK inhibitor PD98059, dominant negative M-RAS, and MC148 antagonist all blocked CCL1/vMIP-I anti-apoptotic activity in thymic lymphoma cells","pmids":["12645948","12525579"],"confidence":"High","gaps":["Physiological significance of CCR8 anti-apoptotic signaling in primary thymocyte selection not established","Downstream effectors of ERK in this context not identified"]},{"year":2004,"claim":"Structure-function analysis revealed that N-terminal tyrosine sulfation (Y14/Y15) is essential for CCL1 binding, establishing the molecular determinants of ligand recognition.","evidence":"Systematic site-directed mutagenesis (Tyr→Phe, Asn→Gln, Thr/Ser→Ala) with flow cytometry and calcium flux readouts; Y14F/Y15F double mutant was essentially inactive","pmids":["14736884"],"confidence":"High","gaps":["No crystal or cryo-EM structure of sulfated CCR8","Whether tyrosine sulfation is regulated in vivo as a signaling switch is unknown"]},{"year":2006,"claim":"CCR8 internalization was shown to be β-arrestin 1/2-dependent and Gαi-independent, and Glu-286 in TM7 was identified as a critical residue for both receptor trafficking and small-molecule agonist binding, dissecting G-protein and arrestin signaling arms.","evidence":"β-arrestin overexpression/depletion, site-directed mutagenesis of Glu286, calcium flux, chemotaxis, and internalization assays","pmids":["17023422","17652183"],"confidence":"High","gaps":["Biased signaling consequences for Treg biology not explored","Full agonist binding pocket model incomplete"]},{"year":2007,"claim":"In vivo studies using CCR8-deficient mice established that mast cell-derived CCL1 signals through CCR8 on CD4+ T cells to orchestrate allergic airway inflammation, and that CCR8 on macrophages drives peritoneal adhesion formation.","evidence":"CCR8−/− mice, mast cell-deficient mice, CCL1 neutralization, adenoviral CCL1 restoration, airway hyperresponsiveness; anti-CCL1/CCR8−/− adhesion models","pmids":["17641040","17404314"],"confidence":"High","gaps":["Relative contribution of CCR8 on T cells vs. macrophages vs. DCs in airway inflammation unresolved","CCR4 was later shown to be more critical for Th2 lung entry"]},{"year":2011,"claim":"Identification of mouse CCL8 as a second endogenous CCR8 agonist driving Th2-mediated eosinophilic skin inflammation resolved a species-specific ligand difference and expanded the CCR8 ligand repertoire.","evidence":"Ccr8−/− and Ccl8−/− mice in chronic atopic dermatitis model; receptor binding and calcium flux confirmed CCL8 selectivity for CCR8 over CCR2","pmids":["21217759"],"confidence":"High","gaps":["Whether human CCL8 acts similarly on human CCR8 not established","Role of CCL8-CCR8 beyond skin unclear"]},{"year":2013,"claim":"CCL18 was identified as a third endogenous human CCR8 ligand, broadening the receptor's physiological ligand repertoire.","evidence":"CCR8 transfection, competitive binding, calcium flux, internalization, cross-desensitization with CCL1, and CCR8−/− mouse Th2 cell migration","pmids":["23999500"],"confidence":"High","gaps":["Relative contribution of CCL18 vs. CCL1 in different tissues not determined","CCL18 has no mouse ortholog, complicating in vivo validation"]},{"year":2017,"claim":"CCL1-CCR8 signaling was found to enhance Treg suppressive function via STAT3-dependent upregulation of FOXP3, CD39, IL-10, and granzyme B, and an autocrine CCL1 loop was discovered, shifting the view of CCR8 from a mere trafficking receptor to a direct modulator of Treg immunosuppressive programs.","evidence":"STAT3 inhibition, CCL1-Ig administration, CCR8−/− adoptive transfer in EAE model, flow cytometry for effector molecules","pmids":["28533380"],"confidence":"High","gaps":["Whether STAT3 activation is direct or indirect not resolved","STAT3 vs. ERK pathway integration in Tregs unknown"]},{"year":2018,"claim":"CCR8 was shown to guide CD301b+ dendritic cell migration from the subcapsular sinus into lymph node parenchyma via Src-kinase signaling, establishing a non-T-cell function for CCR8 in initiating Th2 immunity.","evidence":"CCR8−/− mice, DC migration tracking by imaging and flow cytometry, Src kinase inhibition, CCL8 source identification in CD169+ macrophages","pmids":["30170811"],"confidence":"High","gaps":["Whether CCR8 functions similarly in human lymph nodes not tested","Molecular details of CCR7-CCR8 synergy mechanism unresolved"]},{"year":2019,"claim":"CCR8 was identified as a therapeutic target on tumor-infiltrating Tregs: its expression is driven by TCR/NF-κB signaling, it marks tumor-specific Tregs, and ADCC-competent anti-CCR8 antibodies selectively deplete tumor Tregs to restore antitumor immunity without autoimmunity.","evidence":"scRNA-seq, NF-κB inhibition, nanobody-Fc ADCC assays, NK cell depletion, LLC-OVA and MC38 tumor models, anti-PD-1 synergy","pmids":["33589525"],"confidence":"High","gaps":["CCR8 signaling was shown dispensable for Treg suppressive function in this study, contrasting STAT3/FOXP3 findings from 2017","Human clinical validation of anti-CCR8 therapy pending"]},{"year":2022,"claim":"CCR8+ tumor Tregs were demonstrated to be clonally expanded, tumor-antigen-reactive cells whose antibody-mediated depletion generates durable antitumor memory, and epigenetic regulation of CCR8 expression via histone H3K18 lactylation was discovered linking tumor metabolism to immunosuppression.","evidence":"scRNA-seq with TCR clonotype analysis; anti-CCR8 mAb depletion with tumor rechallenge; ChIP for H3K18 lactylation at CCR8 promoter with reporter assay and LDHA inhibitor","pmids":["35140181","37770937"],"confidence":"High","gaps":["Whether lactylation-driven CCR8 upregulation is reversible therapeutically not tested","Relative contribution of NF-κB vs. lactylation vs. TNFR2 pathways in different tumor types unclear"]},{"year":2024,"claim":"TNFR2/NF-κB signaling was identified as an additional upstream pathway driving CCR8 expression in tumor Tregs, with FOXP3 directly binding the CCR8 promoter, and PD-1 blockade was found to paradoxically increase CCR8+ Treg infiltration.","evidence":"NF-κB/TNFR2 inhibition, FOXP3 ChIP, Tnfr2−/− tumor models, anti-PD-1 combination studies","pmids":["37935468"],"confidence":"Medium","gaps":["Whether TNFR2 blockade combined with anti-CCR8 provides additive benefit is untested","Mechanism of PD-1 blockade-induced CCR8+ Treg expansion unknown"]},{"year":2025,"claim":"CCR8+ Tregs were shown to be essential for maternal-fetal immune tolerance, with decidual NK cell-derived CCL1 recruiting CCR8+ dTregs whose depletion caused fetal loss and whose adoptive transfer rescued it.","evidence":"scRNA-seq, TCR sequencing, CCR8+ dTreg depletion and adoptive transfer in abortion-prone mice, CCL1 source identification","pmids":["40249828"],"confidence":"High","gaps":["Whether CCR8 signaling modulates dTreg suppressive programs or only trafficking is unclear","Human translational relevance for recurrent pregnancy loss not tested"]},{"year":null,"claim":"Key unresolved questions include: whether CCR8 signaling intrinsically enhances Treg suppressive function (conflicting evidence from STAT3 studies vs. dispensability findings), the structural basis of ligand selectivity and biased agonism, and whether anti-CCR8 antibody therapy achieves durable clinical responses in human cancers.","evidence":"","pmids":[],"confidence":"Low","gaps":["No high-resolution structure of CCR8 bound to any ligand","Conflicting reports on whether CCR8 signaling is required for Treg suppressive function vs. serving only as a depletion marker","No published human clinical efficacy data for anti-CCR8 therapy"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,1,7,8,27]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[14,29,35]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,16,17,19]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,12,22,25,29,32,34,36]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[5,6,10]}],"complexes":[],"partners":["CCL1","CCL8","CCL18","ARRB1","ARRB2","GNAI1","FOXP3","STAT3"],"other_free_text":[]},"mechanistic_narrative":"CCR8 is a Gαi-coupled CC chemokine receptor that directs immune cell trafficking, survival, and immunosuppressive function across diverse tissue contexts. Its primary endogenous ligands are CCL1, CCL8, and CCL18, which bind an N-terminal domain requiring tyrosine sulfation at Y14/Y15; ligand engagement activates pertussis toxin-sensitive Gαi signaling, the RAS/MAPK/ERK anti-apoptotic pathway, STAT3-dependent enhancement of Treg suppressive programs (FOXP3, CD39, IL-10, granzyme B), and β-arrestin-mediated receptor internalization [PMID:9211859, PMID:12645948, PMID:28533380, PMID:17023422, PMID:14736884]. CCR8 is preferentially expressed on Th2 cells, FOXP3+ regulatory T cells, dendritic cell subsets, ILC2s, monocytes/macrophages, and thymocytes, where it mediates chemotaxis to sites of allergic inflammation, helminth defense, and tissue homeostasis; in the tumor microenvironment, CCR8 expression is driven by TCR/NF-κB and TNFR2/NF-κB signaling and marks clonally expanded tumor-antigen-reactive Tregs whose selective depletion by ADCC-competent anti-CCR8 antibodies restores antitumor immunity and generates immunological memory without systemic autoimmunity [PMID:9670926, PMID:11560999, PMID:21217759, PMID:35140181, PMID:33757978, PMID:33589525, PMID:37935468]. CCR8 also serves as an HIV-1 co-receptor on thymocytes and T cells and is exploited by viral chemokine mimics encoded by HHV-8 (vMIP-I agonist) and molluscum contagiosum virus (MC148 antagonist) [PMID:9417093, PMID:10419462, PMID:10620615]."},"prefetch_data":{"uniprot":{"accession":"P51685","full_name":"C-C chemokine receptor type 8","aliases":["CC chemokine receptor CHEMR1","CMKBRL2","Chemokine receptor-like 1","CKR-L1","GPR-CY6","GPRCY6","TER1"],"length_aa":355,"mass_kda":40.8,"function":"G protein-coupled receptor that can bind a variety of chemokines, such as CCL1, CCL8, CCL16, CCL18 (PubMed:23999500, PubMed:35041514). Regulates monocyte and eosinophil chemotaxis. Undergoes internalization upon CCL18 binding, leading to induced migration and calcium flux of highly polarized Th2 cells (PubMed:23999500). In microglial cells, promotes phagocytosis with CCL18 through NF-kappa-B and Src signaling pathways (PubMed:35041514). Stimulation of the CCL1-CCR8 signaling axis protects the gut from acute intestinal damage (By similarity) (Microbial infection) Acts as a coreceptor for HIV-1 and HIV-2 viruses (Microbial infection) Acts as a receptor for Kaposi virus protein vCCL1/K6 and thereby inhibits apoptosis in the targeted cells","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/P51685/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CCR8","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CCR8","total_profiled":1310},"omim":[{"mim_id":"605699","title":"UL16-BINDING PROTEIN 3; ULBP3","url":"https://www.omim.org/entry/605699"},{"mim_id":"605698","title":"UL16-BINDING PROTEIN 2; ULBP2","url":"https://www.omim.org/entry/605698"},{"mim_id":"605697","title":"UL16-BINDING PROTEIN 1; ULBP1","url":"https://www.omim.org/entry/605697"},{"mim_id":"603757","title":"CHEMOKINE, CC MOTIF, LIGAND 18; CCL18","url":"https://www.omim.org/entry/603757"},{"mim_id":"601834","title":"CHEMOKINE, CC MOTIF, RECEPTOR 8; CCR8","url":"https://www.omim.org/entry/601834"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":7.2}],"url":"https://www.proteinatlas.org/search/CCR8"},"hgnc":{"alias_symbol":["CY6","TER1","CKR-L1","GPR-CY6","CDw198"],"prev_symbol":["CMKBRL2","CMKBR8"]},"alphafold":{"accession":"P51685","domains":[{"cath_id":"1.20.1070.10","chopping":"38-311","consensus_level":"high","plddt":91.4957,"start":38,"end":311}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P51685","model_url":"https://alphafold.ebi.ac.uk/files/AF-P51685-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P51685-F1-predicted_aligned_error_v6.png","plddt_mean":82.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CCR8","jax_strain_url":"https://www.jax.org/strain/search?query=CCR8"},"sequence":{"accession":"P51685","fasta_url":"https://rest.uniprot.org/uniprotkb/P51685.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P51685/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P51685"}},"corpus_meta":[{"pmid":"11560999","id":"PMC_11560999","title":"Unique chemotactic response profile and specific expression of chemokine receptors CCR4 and CCR8 by CD4(+)CD25(+) regulatory T cells.","date":"2001","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/11560999","citation_count":707,"is_preprint":false},{"pmid":"9820476","id":"PMC_9820476","title":"Selective up-regulation of chemokine receptors CCR4 and CCR8 upon activation of polarized human type 2 Th cells.","date":"1998","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9820476","citation_count":346,"is_preprint":false},{"pmid":"11390417","id":"PMC_11390417","title":"The C-C chemokine receptors CCR4 and CCR8 identify airway T cells of allergen-challenged atopic asthmatics.","date":"2001","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/11390417","citation_count":333,"is_preprint":false},{"pmid":"9670926","id":"PMC_9670926","title":"The chemokine receptor CCR8 is preferentially expressed in Th2 but not Th1 cells.","date":"1998","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9670926","citation_count":329,"is_preprint":false},{"pmid":"33076281","id":"PMC_33076281","title":"CC Chemokines in a Tumor: A Review of Pro-Cancer and Anti-Cancer Properties of Receptors CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 Ligands.","date":"2020","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/33076281","citation_count":301,"is_preprint":false},{"pmid":"21217759","id":"PMC_21217759","title":"Mouse CCL8, a CCR8 agonist, promotes atopic dermatitis by recruiting IL-5+ T(H)2 cells.","date":"2011","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/21217759","citation_count":257,"is_preprint":false},{"pmid":"28533380","id":"PMC_28533380","title":"CCR8+FOXp3+ Treg cells as master drivers of immune regulation.","date":"2017","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/28533380","citation_count":192,"is_preprint":false},{"pmid":"9207005","id":"PMC_9207005","title":"Identification of CCR8: a human monocyte and thymus receptor for the CC chemokine I-309.","date":"1997","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/9207005","citation_count":177,"is_preprint":false},{"pmid":"15814739","id":"PMC_15814739","title":"CCL1-CCR8 interactions: an axis mediating the recruitment of T cells and Langerhans-type dendritic cells to sites of atopic skin inflammation.","date":"2005","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/15814739","citation_count":169,"is_preprint":false},{"pmid":"33589525","id":"PMC_33589525","title":"Therapeutic depletion of CCR8+ tumor-infiltrating regulatory T cells elicits antitumor immunity and synergizes with anti-PD-1 therapy.","date":"2021","source":"Journal for immunotherapy of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/33589525","citation_count":164,"is_preprint":false},{"pmid":"23999500","id":"PMC_23999500","title":"Identification of human CCR8 as a CCL18 receptor.","date":"2013","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23999500","citation_count":157,"is_preprint":false},{"pmid":"35140181","id":"PMC_35140181","title":"CCR8-targeted specific depletion of clonally expanded Treg cells in tumor tissues evokes potent tumor immunity with long-lasting memory.","date":"2022","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/35140181","citation_count":151,"is_preprint":false},{"pmid":"10419462","id":"PMC_10419462","title":"HHV8-encoded vMIP-I selectively engages chemokine receptor CCR8. Agonist and antagonist profiles of viral chemokines.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10419462","citation_count":148,"is_preprint":false},{"pmid":"9211859","id":"PMC_9211859","title":"Identification of CCR8, the receptor for the human CC chemokine I-309.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9211859","citation_count":147,"is_preprint":false},{"pmid":"9417093","id":"PMC_9417093","title":"The CC chemokine I-309 inhibits CCR8-dependent infection by diverse HIV-1 strains.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9417093","citation_count":142,"is_preprint":false},{"pmid":"37770937","id":"PMC_37770937","title":"Oxamate enhances the efficacy of CAR-T therapy against glioblastoma via suppressing ectonucleotidases and CCR8 lactylation.","date":"2023","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/37770937","citation_count":124,"is_preprint":false},{"pmid":"10377196","id":"PMC_10377196","title":"The Kaposi's sarcoma-related herpesvirus (KSHV)-encoded chemokine vMIP-I is a specific agonist for the CC chemokine receptor (CCR)8.","date":"1999","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/10377196","citation_count":117,"is_preprint":false},{"pmid":"17082609","id":"PMC_17082609","title":"CCR8 expression identifies CD4 memory T cells enriched for FOXP3+ regulatory and Th2 effector lymphocytes.","date":"2006","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/17082609","citation_count":115,"is_preprint":false},{"pmid":"10620615","id":"PMC_10620615","title":"A highly selective CC chemokine receptor (CCR)8 antagonist encoded by the poxvirus molluscum contagiosum.","date":"2000","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/10620615","citation_count":108,"is_preprint":false},{"pmid":"30026324","id":"PMC_30026324","title":"Targeting CCR8 Induces Protective Antitumor Immunity and Enhances Vaccine-Induced Responses in Colon Cancer.","date":"2018","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/30026324","citation_count":105,"is_preprint":false},{"pmid":"19062085","id":"PMC_19062085","title":"Contribution of CCR4 and CCR8 to antigen-specific T(H)2 cell trafficking in allergic pulmonary inflammation.","date":"2008","source":"The Journal of allergy and clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19062085","citation_count":105,"is_preprint":false},{"pmid":"18157152","id":"PMC_18157152","title":"TER1, the RNA subunit of fission yeast telomerase.","date":"2007","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18157152","citation_count":99,"is_preprint":false},{"pmid":"30170811","id":"PMC_30170811","title":"The Chemokine Receptor CCR8 Promotes the Migration of Dendritic Cells into the Lymph Node Parenchyma to Initiate the Allergic Immune Response.","date":"2018","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/30170811","citation_count":98,"is_preprint":false},{"pmid":"33757978","id":"PMC_33757978","title":"Fc-Optimized Anti-CCR8 Antibody Depletes Regulatory T Cells in Human Tumor Models.","date":"2021","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/33757978","citation_count":97,"is_preprint":false},{"pmid":"18157149","id":"PMC_18157149","title":"Identification and characterization of the Schizosaccharomyces pombe TER1 telomerase RNA.","date":"2007","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18157149","citation_count":94,"is_preprint":false},{"pmid":"9521068","id":"PMC_9521068","title":"Identification of the CC chemokines TARC and macrophage inflammatory protein-1 beta as novel functional ligands for the CCR8 receptor.","date":"1998","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9521068","citation_count":91,"is_preprint":false},{"pmid":"12496446","id":"PMC_12496446","title":"CCR8 is not essential for the development of inflammation in a mouse model of allergic airway disease.","date":"2003","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/12496446","citation_count":83,"is_preprint":false},{"pmid":"29696074","id":"PMC_29696074","title":"Glycosylated extracellular vesicles released by glioblastoma cells are decorated by CCL18 allowing for cellular uptake via chemokine receptor CCR8.","date":"2018","source":"Journal of extracellular vesicles","url":"https://pubmed.ncbi.nlm.nih.gov/29696074","citation_count":79,"is_preprint":false},{"pmid":"12574386","id":"PMC_12574386","title":"Absence of CCR8 does not impair the response to ovalbumin-induced allergic airway disease.","date":"2003","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/12574386","citation_count":77,"is_preprint":false},{"pmid":"9480837","id":"PMC_9480837","title":"Identification of the chemokine receptor TER1/CCR8 expressed in brain-derived cells and T cells as a new coreceptor for HIV-1 infection.","date":"1998","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/9480837","citation_count":75,"is_preprint":false},{"pmid":"29427415","id":"PMC_29427415","title":"CCR8 Expression Defines Tissue-Resident Memory T Cells in Human Skin.","date":"2018","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/29427415","citation_count":75,"is_preprint":false},{"pmid":"35428909","id":"PMC_35428909","title":"Tumor-derived exosomes drive pre-metastatic niche formation in lung via modulating CCL1+ fibroblast and CCR8+ Treg cell interactions.","date":"2022","source":"Cancer immunology, immunotherapy : CII","url":"https://pubmed.ncbi.nlm.nih.gov/35428909","citation_count":74,"is_preprint":false},{"pmid":"33838058","id":"PMC_33838058","title":"CCR8 marks highly suppressive Treg cells within tumours but is dispensable for their accumulation and suppressive function.","date":"2021","source":"Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/33838058","citation_count":73,"is_preprint":false},{"pmid":"11133740","id":"PMC_11133740","title":"The chemokine receptor CCR8 mediates human endothelial cell chemotaxis induced by I-309 and Kaposi sarcoma herpesvirus-encoded vMIP-I and by lipoprotein(a)-stimulated endothelial cell conditioned medium.","date":"2001","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11133740","citation_count":72,"is_preprint":false},{"pmid":"9469461","id":"PMC_9469461","title":"Identification of CCR8 as the specific receptor for the human beta-chemokine I-309: cloning and molecular characterization of murine CCR8 as the receptor for TCA-3.","date":"1998","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9469461","citation_count":65,"is_preprint":false},{"pmid":"17947648","id":"PMC_17947648","title":"Recruitment and activation of macrophages by pathogenic CD4 T cells in type 1 diabetes: evidence for involvement of CCR8 and CCL1.","date":"2007","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/17947648","citation_count":63,"is_preprint":false},{"pmid":"14576057","id":"PMC_14576057","title":"Chemokine receptor-8 (CCR8) mediates human vascular smooth muscle cell chemotaxis and metalloproteinase-2 secretion.","date":"2003","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/14576057","citation_count":61,"is_preprint":false},{"pmid":"31537642","id":"PMC_31537642","title":"A CCL1/CCR8-dependent feed-forward mechanism drives ILC2 functions in type 2-mediated inflammation.","date":"2019","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/31537642","citation_count":58,"is_preprint":false},{"pmid":"15699124","id":"PMC_15699124","title":"CCR8 is expressed by antigen-elicited, IL-10-producing CD4+CD25+ T cells, which regulate Th2-mediated granuloma formation in mice.","date":"2005","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/15699124","citation_count":58,"is_preprint":false},{"pmid":"17404314","id":"PMC_17404314","title":"Inhibition of CCL1-CCR8 interaction prevents aggregation of macrophages and development of peritoneal adhesions.","date":"2007","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/17404314","citation_count":56,"is_preprint":false},{"pmid":"17641040","id":"PMC_17641040","title":"Coordinated involvement of mast cells and T cells in allergic mucosal inflammation: critical role of the CC chemokine ligand 1:CCR8 axis.","date":"2007","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/17641040","citation_count":56,"is_preprint":false},{"pmid":"23363815","id":"PMC_23363815","title":"Expansion of CCR8(+) inflammatory myeloid cells in cancer patients with urothelial and renal carcinomas.","date":"2013","source":"Clinical cancer research : an official journal of the American Association for Cancer Research","url":"https://pubmed.ncbi.nlm.nih.gov/23363815","citation_count":55,"is_preprint":false},{"pmid":"8816377","id":"PMC_8816377","title":"Molecular cloning of TER1, a chemokine receptor-like gene expressed by lymphoid tissues.","date":"1996","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/8816377","citation_count":53,"is_preprint":false},{"pmid":"12645948","id":"PMC_12645948","title":"CCR8-dependent activation of the RAS/MAPK pathway mediates anti-apoptotic activity of I-309/ CCL1 and vMIP-I.","date":"2003","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/12645948","citation_count":48,"is_preprint":false},{"pmid":"17652183","id":"PMC_17652183","title":"Molecular interaction of a potent nonpeptide agonist with the chemokine receptor CCR8.","date":"2007","source":"Molecular pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/17652183","citation_count":47,"is_preprint":false},{"pmid":"16195226","id":"PMC_16195226","title":"Sap1p binds to Ter1 at the ribosomal DNA of Schizosaccharomyces pombe and causes polar replication fork arrest.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16195226","citation_count":46,"is_preprint":false},{"pmid":"30592282","id":"PMC_30592282","title":"CCL18 enhances migration, invasion and EMT by binding CCR8 in bladder cancer cells.","date":"2018","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/30592282","citation_count":46,"is_preprint":false},{"pmid":"12050188","id":"PMC_12050188","title":"Increased responsiveness of murine eosinophils to MIP-1beta (CCL4) and TCA-3 (CCL1) is mediated by their specific receptors, CCR5 and CCR8.","date":"2002","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/12050188","citation_count":46,"is_preprint":false},{"pmid":"23811304","id":"PMC_23811304","title":"Possible involvement of CCL1-CCR8 interaction in lymphocytic recruitment in IgG4-related sclerosing cholangitis.","date":"2013","source":"Journal of hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/23811304","citation_count":45,"is_preprint":false},{"pmid":"32367308","id":"PMC_32367308","title":"CCR8 blockade primes anti-tumor immunity through intratumoral regulatory T cells destabilization in muscle-invasive bladder cancer.","date":"2020","source":"Cancer immunology, immunotherapy : CII","url":"https://pubmed.ncbi.nlm.nih.gov/32367308","citation_count":45,"is_preprint":false},{"pmid":"10888633","id":"PMC_10888633","title":"CCR8 on human thymocytes functions as a human immunodeficiency virus type 1 coreceptor.","date":"2000","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/10888633","citation_count":44,"is_preprint":false},{"pmid":"10910894","id":"PMC_10910894","title":"LEC induces chemotaxis and adhesion by interacting with CCR1 and CCR8.","date":"2000","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/10910894","citation_count":41,"is_preprint":false},{"pmid":"17181556","id":"PMC_17181556","title":"CCR7, CCR8, CCR9 and CCR10 in the mouse hippocampal CA1 area and the dentate gyrus during and after pilocarpine-induced status epilepticus.","date":"2007","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17181556","citation_count":39,"is_preprint":false},{"pmid":"35354899","id":"PMC_35354899","title":"The impact of CCR8+ regulatory T cells on cytotoxic T cell function in human lung cancer.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35354899","citation_count":38,"is_preprint":false},{"pmid":"12525579","id":"PMC_12525579","title":"The chemokine receptor CCR8 mediates rescue from dexamethasone-induced apoptosis via an ERK-dependent pathway.","date":"2003","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/12525579","citation_count":38,"is_preprint":false},{"pmid":"31121182","id":"PMC_31121182","title":"Disruption of the CCL1-CCR8 axis inhibits vascular Treg recruitment and function and promotes atherosclerosis in mice.","date":"2019","source":"Journal of molecular and cellular cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/31121182","citation_count":38,"is_preprint":false},{"pmid":"36352891","id":"PMC_36352891","title":"Differential expression of CCR8 in tumors versus normal tissue allows specific depletion of tumor-infiltrating T regulatory cells by GS-1811, a novel Fc-optimized anti-CCR8 antibody.","date":"2022","source":"Oncoimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/36352891","citation_count":36,"is_preprint":false},{"pmid":"14736884","id":"PMC_14736884","title":"Analysis of post-translational CCR8 modifications and their influence on receptor activity.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14736884","citation_count":36,"is_preprint":false},{"pmid":"28961489","id":"PMC_28961489","title":"Spinal CCL1/CCR8 signaling interplay as a potential therapeutic target - Evidence from a mouse diabetic neuropathy model.","date":"2017","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/28961489","citation_count":36,"is_preprint":false},{"pmid":"22215813","id":"PMC_22215813","title":"Schizosaccharomyces pombe Ccq1 and TER1 bind the 14-3-3-like domain of Est1, which promotes and stabilizes telomerase-telomere association.","date":"2012","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/22215813","citation_count":35,"is_preprint":false},{"pmid":"24714157","id":"PMC_24714157","title":"Chemokine receptor CCR8 is required for lipopolysaccharide-triggered cytokine production in mouse peritoneal macrophages.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24714157","citation_count":35,"is_preprint":false},{"pmid":"34025655","id":"PMC_34025655","title":"Immunomodulation of T Helper Cells by Tumor Microenvironment in Oral Cancer Is Associated With CCR8 Expression and Rapid Membrane Vitamin D Signaling Pathway.","date":"2021","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/34025655","citation_count":34,"is_preprint":false},{"pmid":"20455898","id":"PMC_20455898","title":"Expression of CCR8 is increased in asthma.","date":"2010","source":"Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/20455898","citation_count":34,"is_preprint":false},{"pmid":"16640325","id":"PMC_16640325","title":"Design, synthesis, and progress toward optimization of potent small molecule antagonists of CC chemokine receptor 8 (CCR8).","date":"2006","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16640325","citation_count":33,"is_preprint":false},{"pmid":"20947116","id":"PMC_20947116","title":"Coreceptor usage by HIV-1 and HIV-2 primary isolates: the relevance of CCR8 chemokine receptor as an alternative coreceptor.","date":"2010","source":"Virology","url":"https://pubmed.ncbi.nlm.nih.gov/20947116","citation_count":33,"is_preprint":false},{"pmid":"17023422","id":"PMC_17023422","title":"Structure/function relationships of CCR8 agonists and antagonists. Amino-terminal extension of CCL1 by a single amino acid generates a partial agonist.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17023422","citation_count":31,"is_preprint":false},{"pmid":"37935468","id":"PMC_37935468","title":"Blockade of TNF-α/TNFR2 signalling suppresses colorectal cancer and enhances the efficacy of anti-PD1 immunotherapy by decreasing CCR8+T regulatory cells.","date":"2024","source":"Journal of molecular cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/37935468","citation_count":29,"is_preprint":false},{"pmid":"35158783","id":"PMC_35158783","title":"Chemokine Receptor-Targeted Therapies: Special Case for CCR8.","date":"2022","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/35158783","citation_count":29,"is_preprint":false},{"pmid":"35417708","id":"PMC_35417708","title":"Microglia/macrophage-derived human CCL18 promotes glioma progression via CCR8-ACP5 axis analyzed in humanized slice model.","date":"2022","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/35417708","citation_count":29,"is_preprint":false},{"pmid":"16221874","id":"PMC_16221874","title":"Identification and characterization of a potent, selective nonpeptide agonist of the CC chemokine receptor CCR8.","date":"2005","source":"Molecular pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/16221874","citation_count":28,"is_preprint":false},{"pmid":"39080766","id":"PMC_39080766","title":"Targeting tumor-infiltrating CCR8+ regulatory T cells induces antitumor immunity through functional restoration of CD4+ Tconvs and CD8+ T cells in colorectal cancer.","date":"2024","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/39080766","citation_count":21,"is_preprint":false},{"pmid":"35973731","id":"PMC_35973731","title":"Blocking CCL8-CCR8-Mediated Early Allograft Inflammation Improves Kidney Transplant Function.","date":"2022","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/35973731","citation_count":21,"is_preprint":false},{"pmid":"12551893","id":"PMC_12551893","title":"Genomic organization and evolution of the CX3CR1/CCR8 chemokine receptor locus.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12551893","citation_count":21,"is_preprint":false},{"pmid":"37420296","id":"PMC_37420296","title":"S-531011, a Novel Anti-Human CCR8 Antibody, Induces Potent Antitumor Responses through Depletion of Tumor-Infiltrating CCR8-Expressing Regulatory T Cells.","date":"2023","source":"Molecular cancer therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/37420296","citation_count":21,"is_preprint":false},{"pmid":"39890548","id":"PMC_39890548","title":"CCR8: a promising therapeutic target against tumor-infiltrating regulatory T cells.","date":"2025","source":"Trends in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/39890548","citation_count":20,"is_preprint":false},{"pmid":"36988587","id":"PMC_36988587","title":"Discovery of a Potent and Selective CCR8 Small Molecular Antagonist IPG7236 for the Treatment of Cancer.","date":"2023","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/36988587","citation_count":20,"is_preprint":false},{"pmid":"15075267","id":"PMC_15075267","title":"Genetic dissection of the Kluyveromyces lactis telomere and evidence for telomere capping defects in TER1 mutants with long telomeres.","date":"2004","source":"Eukaryotic cell","url":"https://pubmed.ncbi.nlm.nih.gov/15075267","citation_count":20,"is_preprint":false},{"pmid":"17693327","id":"PMC_17693327","title":"Combination of 17beta-estradiol with the environmental pollutant TCDD is involved in pathogenesis of endometriosis via up-regulating the chemokine I-309-CCR8.","date":"2007","source":"Fertility and sterility","url":"https://pubmed.ncbi.nlm.nih.gov/17693327","citation_count":20,"is_preprint":false},{"pmid":"22209712","id":"PMC_22209712","title":"Orally bioavailable allosteric CCR8 antagonists inhibit dendritic cell, T cell and eosinophil migration.","date":"2011","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/22209712","citation_count":20,"is_preprint":false},{"pmid":"33460563","id":"PMC_33460563","title":"Chemokine (C-C Motif) Ligand 1 Derived from Tumor-Associated Macrophages Contributes to Esophageal Squamous Cell Carcinoma Progression via CCR8-Mediated Akt/Proline-Rich Akt Substrate of 40 kDa/Mammalian Target of Rapamycin Pathway.","date":"2021","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/33460563","citation_count":19,"is_preprint":false},{"pmid":"22479563","id":"PMC_22479563","title":"C-terminal clipping of chemokine CCL1/I-309 enhances CCR8-mediated intracellular calcium release and anti-apoptotic activity.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22479563","citation_count":19,"is_preprint":false},{"pmid":"17850582","id":"PMC_17850582","title":"Expression of chemokine receptors CCR7 and CCR8 in the CNS during ChREAE.","date":"2007","source":"Scandinavian journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/17850582","citation_count":18,"is_preprint":false},{"pmid":"37350632","id":"PMC_37350632","title":"Immunotherapy Targeting CCR8+ Regulatory T Cells Induces Antitumor Effects via Dramatic Changes to the Intratumor CD8+ T Cell Profile.","date":"2023","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/37350632","citation_count":17,"is_preprint":false},{"pmid":"21976223","id":"PMC_21976223","title":"CCR8 signaling influences Toll-like receptor 4 responses in human macrophages in inflammatory diseases.","date":"2011","source":"Clinical and vaccine immunology : CVI","url":"https://pubmed.ncbi.nlm.nih.gov/21976223","citation_count":17,"is_preprint":false},{"pmid":"40249828","id":"PMC_40249828","title":"CCR8+ decidual regulatory T cells maintain maternal-fetal immune tolerance during early pregnancy.","date":"2025","source":"Science immunology","url":"https://pubmed.ncbi.nlm.nih.gov/40249828","citation_count":16,"is_preprint":false},{"pmid":"35377236","id":"PMC_35377236","title":"C8Mab-3: An Anti-Mouse CCR8 Monoclonal Antibody for Immunocytochemistry.","date":"2022","source":"Monoclonal antibodies in immunodiagnosis and immunotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/35377236","citation_count":16,"is_preprint":false},{"pmid":"25344933","id":"PMC_25344933","title":"CCR8 regulates contact hypersensitivity by restricting cutaneous dendritic cell migration to the draining lymph nodes.","date":"2014","source":"International immunology","url":"https://pubmed.ncbi.nlm.nih.gov/25344933","citation_count":16,"is_preprint":false},{"pmid":"31270368","id":"PMC_31270368","title":"CCR8 leads to eosinophil migration and regulates neutrophil migration in murine allergic enteritis.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/31270368","citation_count":16,"is_preprint":false},{"pmid":"35483056","id":"PMC_35483056","title":"Development of an Anti-Mouse CCR8 Monoclonal Antibody (C8Mab-1) for Flow Cytometry and Immunocytochemistry.","date":"2022","source":"Monoclonal antibodies in immunodiagnosis and immunotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/35483056","citation_count":16,"is_preprint":false},{"pmid":"31121204","id":"PMC_31121204","title":"Spinal CCL1/CCR8 regulates phosphorylation of GluA1-containing AMPA receptor in postoperative pain after tibial fracture and orthopedic surgery in mice.","date":"2019","source":"Neuroscience research","url":"https://pubmed.ncbi.nlm.nih.gov/31121204","citation_count":16,"is_preprint":false},{"pmid":"11493620","id":"PMC_11493620","title":"MC148 encoded by human molluscum contagiosum poxvirus is an antagonist for human but not murine CCR8.","date":"2001","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/11493620","citation_count":16,"is_preprint":false},{"pmid":"40056978","id":"PMC_40056978","title":"Selective Depletion of CCR8+Treg Cells Enhances the Antitumor Immunity of Cytotoxic T Cells in Lung Cancer by Dendritic Cells.","date":"2025","source":"Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/40056978","citation_count":15,"is_preprint":false},{"pmid":"22708643","id":"PMC_22708643","title":"Molecular requirements for inhibition of the chemokine receptor CCR8--probe-dependent allosteric interactions.","date":"2012","source":"British journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/22708643","citation_count":15,"is_preprint":false},{"pmid":"17321573","id":"PMC_17321573","title":"Remission of chronic fungal asthma in the absence of CCR8.","date":"2007","source":"The Journal of allergy and clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/17321573","citation_count":15,"is_preprint":false},{"pmid":"37950246","id":"PMC_37950246","title":"CD4+CCR8+ Tregs in ovarian cancer: a potential effector Tregs for immune regulation.","date":"2023","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37950246","citation_count":14,"is_preprint":false},{"pmid":"25617117","id":"PMC_25617117","title":"In silico characterization of binding mode of CCR8 inhibitor: homology modeling, docking and membrane based MD simulation study.","date":"2015","source":"Journal of biomolecular structure & dynamics","url":"https://pubmed.ncbi.nlm.nih.gov/25617117","citation_count":14,"is_preprint":false},{"pmid":"33872569","id":"PMC_33872569","title":"Biological characterization of ligands targeting the human CC chemokine receptor 8 (CCR8) reveals the biased signaling properties of small molecule agonists.","date":"2021","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/33872569","citation_count":14,"is_preprint":false},{"pmid":"29248693","id":"PMC_29248693","title":"Neuropathic pain inhibitor, RAP-103, is a potent inhibitor of microglial CCL1/CCR8.","date":"2017","source":"Neurochemistry international","url":"https://pubmed.ncbi.nlm.nih.gov/29248693","citation_count":14,"is_preprint":false},{"pmid":"38856863","id":"PMC_38856863","title":"Selective depletion of tumor-infiltrating regulatory T cells with BAY 3375968, a novel Fc-optimized anti-CCR8 antibody.","date":"2024","source":"Clinical and experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/38856863","citation_count":13,"is_preprint":false},{"pmid":"35377281","id":"PMC_35377281","title":"TGF-β-induced CCR8 promoted macrophage transdifferentiation into myofibroblast-like cells.","date":"2022","source":"Experimental lung research","url":"https://pubmed.ncbi.nlm.nih.gov/35377281","citation_count":13,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":52026,"output_tokens":10585,"usd":0.157426},"stage2":{"model":"claude-opus-4-6","input_tokens":14616,"output_tokens":4284,"usd":0.27027},"total_usd":0.427696,"stage1_batch_id":"msgbatch_011kfMfE81o6CTcyhVUqumuW","stage2_batch_id":"msgbatch_01DTputS6WNkH745x1nVSoBo","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"CCR8 was identified as the specific receptor for the human CC chemokine I-309 (CCL1). Transfection of the CY6/TER1/CKR-L1 open reading frame into mouse pre-B cells conferred calcium flux and chemotaxis in response to I-309 (EC50 ~2 nM), while 20 other chemokines were inactive. Signaling was sensitive to pertussis toxin, indicating coupling to a Gi-type G protein.\",\n      \"method\": \"Receptor transfection into pre-B cells, calcium flux assay, chemotaxis assay, pertussis toxin inhibition, 125I-I-309 binding (Kd ~1.2 nM)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with functional assays; independently replicated in same year by Tiffany et al.\",\n      \"pmids\": [\"9211859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"CCR8 is constitutively expressed in monocytes and thymus, functions as a monocyte chemoattractant receptor for I-309, and inhibits apoptosis in thymic cell lines. Signaling is pertussis toxin-sensitive, confirming Gi coupling.\",\n      \"method\": \"Transfection, calcium flux, chemotaxis, pertussis toxin inhibition, northern blot for tissue expression\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution in transfected cells with multiple functional readouts, replicated across labs\",\n      \"pmids\": [\"9207005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CCR8 is preferentially expressed on polarized Th2 cells (both human and mouse) and not Th1 cells. The CCR8 ligands I-309 and TCA-3 act as potent chemoattractants specifically for Th2-polarized cells.\",\n      \"method\": \"Northern blot, RT-PCR, chemotaxis assay with polarized T cell subsets, mouse CCR8 cloning\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods, replicated across human and mouse systems by multiple labs\",\n      \"pmids\": [\"9670926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CCR8 expression on Th2 cells is transiently upregulated following TCR and CD28 engagement, and this upregulation is IL-4-independent. Upregulation enhances functional chemotactic responses to I-309 and TARC.\",\n      \"method\": \"Flow cytometry, chemotaxis assay, cytokine neutralization\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean functional experiment with cytokine blockade, single lab\",\n      \"pmids\": [\"9820476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"TARC (CCL17) and MIP-1β (CCL4) were identified as additional functional CCR8 ligands, inducing chemotaxis in CCR8-transfected Jurkat cells.\",\n      \"method\": \"Stable transfection of CCR8 into Jurkat cells, chemotaxis assay\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional assay in transfected cells, single lab; later studies suggest primary ligand is CCL1\",\n      \"pmids\": [\"9521068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CCR8 serves as a co-receptor for HIV-1 infection; diverse T-cell tropic, dual-tropic, and macrophage-tropic HIV-1 strains can use CCR8, and I-309 (CCL1) potently inhibits HIV-1 envelope-mediated cell-cell fusion and virus infection through CCR8.\",\n      \"method\": \"Cell-cell fusion assay, virus infection assay, calcium flux, flow cytometry, pertussis toxin inhibition\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple functional assays, replicated by multiple labs (Jinno et al. 1998, Lee et al. 2000, Calado et al. 2010)\",\n      \"pmids\": [\"9417093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"TER1/CCR8 is expressed in brain-derived CD4+ cells and T cells and functions as a co-receptor for brain-cell-tropic HIV-1 variants that are resistant to M-tropic and T-tropic strains.\",\n      \"method\": \"Degenerate PCR, expression of TER1 in CD4+ resistant cells, infection assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct infection assay establishing CCR8 as functional co-receptor in brain-derived cells, single lab\",\n      \"pmids\": [\"9480837\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"HHV-8-encoded vMIP-I selectively binds to and signals through CCR8 as an agonist (inducing Ca2+ flux in T cells), while vMIP-II and vMCC-I act as CCR8 antagonists. A comprehensive ligand binding fingerprint for CCR8 identified four high-affinity ligands (vMIP-I, vMIP-II, vMCC-I, and human I-309).\",\n      \"method\": \"Competitive radioligand binding with 65 chemokines, calcium mobilization assay in human T cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — comprehensive in vitro pharmacological characterization with multiple orthogonal assays, replicated by Endres et al. 1999\",\n      \"pmids\": [\"10419462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"vMIP-I (KSHV-encoded) is a specific agonist for CCR8: it binds with high affinity, induces calcium flux, and drives chemotaxis in CCR8-transfected Y3 cells. vMIP-I does not interact with CCR5 or 11 other receptors tested.\",\n      \"method\": \"Calcium flux assay, chemotaxis assay, competition binding in CCR8-transfected cells\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution in transfected cells with multiple functional assays, consistent with Dairaghi et al.\",\n      \"pmids\": [\"10377196\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The molluscum contagiosum poxvirus-encoded MC148 is a highly selective CCR8 antagonist that binds with high affinity only to CCR8 among 16 chemokine receptors and blocks I-309/CCR8-induced calcium mobilization and chemotaxis without affecting other chemokine receptors.\",\n      \"method\": \"Competitive binding with radiolabeled chemokines, calcium mobilization assay, chemotaxis assay across 16 receptors\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — comprehensive pharmacological profiling across 16 receptors, confirmed antagonism with functional readouts\",\n      \"pmids\": [\"10620615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CCR8 is expressed on human thymocytes (both immature and mature) and functions as an HIV-1 co-receptor: I-309 inhibits fusion of thymocytes with HIV-1 X4 or X4R5 envelope-expressing cells and partially inhibits productive HIV-1 infection.\",\n      \"method\": \"125I-I-309 binding on primary thymocytes, cell-cell fusion assay, productive infection assay\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct binding and functional infection assays on primary human cells\",\n      \"pmids\": [\"10888633\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"CCR8 is expressed on human vascular endothelial cells (HUVECs) and mediates endothelial cell chemotaxis in response to I-309 and vMIP-I. Pertussis toxin and anti-CCR8 antibody blocked this chemotaxis, confirming G protein-coupled, CCR8-dependent signaling in endothelial cells.\",\n      \"method\": \"Chemotaxis assay, antibody neutralization, pertussis toxin inhibition, RNA blot, immunohistochemistry\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal inhibitory approaches in a novel cell type, single lab\",\n      \"pmids\": [\"11133740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"CCR8 and CCR4 are specifically expressed on human CD4+CD25+ regulatory T cells (Tregs), which vigorously respond to CCR8 ligands CCL1 and CCL22. CCR4 ligands (CCL17, CCL22) secreted by mature dendritic cells preferentially attract Treg cells, and the migrated CCR8/CCR4-expressing population shows reduced alloproliferative response.\",\n      \"method\": \"Flow cytometry, chemotaxis assay with sorted CD4+CD25+ vs CD4+CD25- T cells, functional alloproliferation assay\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods establishing CCR8 as specific marker and functional receptor on Tregs, highly cited and replicated\",\n      \"pmids\": [\"11560999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CCR8 mediates human vascular smooth muscle cell (VSMC) chemotaxis in response to CCL1 and vCCL1, and this is blocked by anti-CCR8 antibody and pertussis toxin. CCR8 activation by CCL1 also induces pro-MMP-2 mRNA and protein secretion, which contributes to VSMC migration, as shown by MMP-2 antibody inhibition.\",\n      \"method\": \"Chemotaxis assay, antibody/pertussis toxin inhibition, RT-PCR, MMP-2 ELISA/western blot, poxvirus MC148 blockade\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple mechanistic readouts with specific blockers, single lab\",\n      \"pmids\": [\"14576057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CCR8-dependent activation of the RAS/MAPK (ERK1/2) pathway mediates anti-apoptotic activity of CCL1 and vMIP-I in thymic lymphoma cells. This was demonstrated using pertussis toxin, the MEK inhibitor PD98059, a dominant negative M-RAS, and the CCR8 antagonist MC148.\",\n      \"method\": \"Apoptosis assay, pertussis toxin inhibition, ERK phosphorylation assay, MEK inhibitor (PD98059), dominant negative M-RAS, MC148 antagonist, CCR8-transfected CHO cells\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple pharmacological and genetic tools establish CCR8→RAS/MAPK→anti-apoptosis pathway\",\n      \"pmids\": [\"12645948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CCR8 mediates rescue of thymic lymphoma cells and murine thymocytes from dexamethasone-induced apoptosis via an ERK-dependent pathway. The CCR8 antagonist MC148 specifically blocks the anti-apoptotic activity of vMIP-I and CCL1.\",\n      \"method\": \"Apoptosis assay, ERK pathway analysis, MC148 antagonist blockade, CCR8-specific agonist vMIP-1\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — specific receptor attribution confirmed by selective antagonist, single lab\",\n      \"pmids\": [\"12525579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Post-translational modifications of murine CCR8 regulate its activity: tyrosine sulfation at positions Y14/Y15 is critical for CCL1 binding and calcium signaling (Y14F/Y15F double mutant essentially inactive), while N-linked glycosylation at N8 and O-linked modifications at T10/T12 have minor effects on ligand binding.\",\n      \"method\": \"Site-directed mutagenesis (Tyr→Phe, Asn→Gln, Thr/Ser→Ala), flow cytometry with CCL1-Fc fusion, calcium flux assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis with multiple functional readouts establishing structure-function relationships\",\n      \"pmids\": [\"14736884\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CCR8 is expressed on Langerhans-type dendritic cells (DCs), mast cells, and dermal endothelial cells. CCL1 recruits both T cells and Langerhans cell-like DCs, and synergizes with CXCL12 (SDF-1α) in promoting this recruitment. CCR8 is recruited from intracytoplasmic stores to the cell surface upon T cell activation.\",\n      \"method\": \"Immunofluorescence, flow cytometry, in vitro chemotaxis assay, in vitro DC differentiation, CCL1/CXCL12 synergy experiments\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple cell types and functional assays, single lab\",\n      \"pmids\": [\"15814739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CCR8 expression defines IL-10-producing CD4+CD25+ T cells in Th2-type granulomatous inflammation. CCR8-deficient mice showed significantly impaired IL-10 production and reduced granuloma eosinophils in a Schistosoma egg-antigen model; adoptive transfer of CCR8+/+ CD4+ T cells corrected these defects.\",\n      \"method\": \"CCR8-/- mice, adoptive transfer, cytokine mRNA quantification, BAL cell analysis\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with adoptive transfer rescue, single lab\",\n      \"pmids\": [\"15699124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CCR8 undergoes beta-arrestin 1/2-dependent internalization upon ligand binding (CCL1 and vMIP-I), independently of Gαi signaling. NH2-terminal extension of CCL1 by a serine residue (Ser-CCL1) generates a partial agonist, indicating the NH2 terminus plays a role in binding to an intrahelical site. Glu-286 in TM helix 7 is critical for receptor surface trafficking, and CCL7 selectively antagonizes viral (but not host) chemokine activity at CCR8.\",\n      \"method\": \"Calcium flux, chemotaxis, receptor internalization assay, beta-arrestin expression, site-directed mutagenesis, CCL7 antagonism experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple orthogonal functional assays with mutagenesis establishing mechanism of ligand binding and receptor trafficking\",\n      \"pmids\": [\"17023422\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"A non-peptide CCR8 agonist (LMD-009) interacts with CCR8 through a binding pocket involving GluVII:06 (Glu286) as a critical anchor point, shared with non-peptide antagonists targeting CCR1, CCR2, and CCR5. Ala substitution of Glu286 reduced agonist potency ~1000-fold; Ala substitution of PheVI:16 (Phe254) produced a 19-fold gain-of-function. 29 mutations across 25 residues mapped the binding pocket.\",\n      \"method\": \"Site-directed mutagenesis (29 mutations), calcium flux, chemotaxis, inositol phosphate accumulation, 125I-CCL1 competitive binding\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis across the binding pocket with multiple functional assays\",\n      \"pmids\": [\"17652183\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CCR8 is expressed on peritoneal macrophages (PMφ) and up-regulated by inflammatory stimuli. CCL1 produced by both PMφ and peritoneal mesothelial cells (PMCs) promotes CCR8 expression (autocrine loop), drives cell aggregation, and upregulates plasminogen activator inhibitor-1. CCR8-deficient mice and anti-CCL1-treated mice exhibit significantly reduced postoperative peritoneal adhesions.\",\n      \"method\": \"CCR8-/- mice, anti-CCL1 neutralizing antibody, in vitro cell aggregation assay, RT-PCR, flow cytometry\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO and antibody blockade with in vitro mechanistic follow-up, single lab\",\n      \"pmids\": [\"17404314\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mast cell-derived CCL1 signals through CCR8 on CD4+ T lymphocytes to orchestrate mucosal lung inflammation, airway hyperresponsiveness, and mucus hypersecretion. CCR8 deficiency or CCL1 neutralization reduced these responses to the same degree as mast cell deficiency; adenoviral CCL1 delivery to lungs of mast cell-deficient mice restored the inflammatory phenotype.\",\n      \"method\": \"CCR8-/- mice, mast cell-deficient mice, CCL1 neutralization, adenoviral CCL1 delivery, airway hyperresponsiveness measurements, BAL cytokine analysis\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic models and epistasis experiments establishing mast cell CCL1 → CCR8+ CD4+ T cell axis, single lab\",\n      \"pmids\": [\"17641040\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CCR8 expression in CD4+CD25+ Tregs recruited to the pancreas during adoptive transfer of diabetogenic T cell clones; the only chemokine detectable ex vivo was CCL1, suggesting CCL1/CCR8 interaction mediates macrophage recruitment and activation (IL-1β, TNF-α, NO production) in type 1 diabetes.\",\n      \"method\": \"Adoptive transfer model, flow cytometry, ex vivo chemokine protein detection, macrophage functional assays\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — correlative in vivo localization without direct mechanistic manipulation of CCR8\",\n      \"pmids\": [\"17947648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Using adoptive transfer of CCR4-deficient or CCR8-deficient antigen-specific Th2 cells, CCR4 (not CCR8) was found to be required for efficient entry of antigen-specific Th2 cells into the lung and airways in allergic pulmonary inflammation. CCR8-deficient Th2 cells showed normal or increased accumulation in the lung.\",\n      \"method\": \"Adoptive transfer of CCR4-/- or CCR8-/- antigen-specific Th2 cells, flow cytometry, cytokine measurement, eosinophil/mucus quantification\",\n      \"journal\": \"The Journal of allergy and clinical immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean adoptive transfer genetic epistasis experiment with specific phenotypic readouts\",\n      \"pmids\": [\"19062085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Mouse CCL8 is a selective CCR8 agonist (not a CCR2 agonist, unlike all other MCP chemokines). CCL8 responsiveness defined a population of CCR8-expressing inflammatory Th2 cells enriched for IL-5. CCR8- and CCL8-deficient mice showed markedly reduced eosinophilic inflammation in chronic atopic dermatitis. Adoptive transfer established CCR8 as a key regulator of Th2 cell recruitment into allergen-inflamed skin.\",\n      \"method\": \"Ccr8-/- and Ccl8-/- mice, adoptive transfer, receptor binding assays, calcium flux, atopic dermatitis mouse model, eosinophil quantification\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — dual KO mice with adoptive transfer, multiple cell and tissue readouts, high-impact journal\",\n      \"pmids\": [\"21217759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"C-terminal clipping of CCL1 by carboxypeptidase M (CPM) augments CCR8-mediated intracellular calcium release and anti-apoptotic activity in BW5147 cells, while reducing CCL1 binding affinity to CCR8, revealing a proteolytic regulatory mechanism for the CCL1-CCR8 axis.\",\n      \"method\": \"In vitro CPM enzymatic cleavage, mass spectrometry, calcium mobilization assay, binding assay, apoptosis assay with CPM inhibitor control\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic reconstitution with multiple functional readouts; single lab\",\n      \"pmids\": [\"22479563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CCR8 is a functional receptor for CCL18: CCL18 induces chemotaxis and calcium flux in CCR8-transfected cells, binds CCR8 with high affinity, induces CCR8 internalization, and competes with CCL1 for CCR8 binding. CCL1 and CCL18 cross-desensitize CCR8 on transfected cells and human Th2 cells. CCR8-deficient mouse Th2 cells fail to migrate to CCL18.\",\n      \"method\": \"CCR8 transfection, chemotaxis assay, calcium flux, competitive binding, receptor internalization, cross-desensitization, Ccr8-/- mouse Th2 cell migration\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple orthogonal methods including KO validation establishing CCL18 as CCR8 ligand\",\n      \"pmids\": [\"23999500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CCR8 is required for LPS-triggered cytokine production (TNF-α, IL-6, IL-10) specifically in peritoneal macrophages but not bone marrow-derived macrophages. CCR8-dependent cytokine production involves cross-talk with TLR-4 signaling via JNK and NF-κB pathways. A CCR8 antagonist (R243) phenocopied CCR8 deficiency and attenuated peritoneal adhesions in vivo.\",\n      \"method\": \"CCR8-/- mice, TLR ligand stimulation, cytokine ELISA, JNK/NF-κB inhibitors, R243 CCR8 antagonist, in vivo adhesion model\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO and pharmacological antagonist with signaling pathway dissection, single lab\",\n      \"pmids\": [\"24714157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CCL1 signaling through CCR8 on Tregs induces STAT3-dependent upregulation of FOXp3, CD39, IL-10, and granzyme B, enhancing Treg suppressive activity. CCL1 produced by Tregs at autoimmune sites creates a self-feeding autocrine loop that upregulates CCR8 on Tregs. CCR8-/- mice in adoptive transfer experiments confirmed the essential role of CCR8 in Treg-mediated suppression of EAE.\",\n      \"method\": \"Human PBMC activation assays, STAT3 inhibition, CCL1-Ig administration, CCR8-/- mouse adoptive transfer, EAE model, flow cytometry for CD39/granzyme B/IL-10\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal experiments including KO adoptive transfer and pharmacological intervention identifying specific signaling pathway\",\n      \"pmids\": [\"28533380\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CCR8 on CD301b+ dendritic cells (DCs) mediates their migration from the subcapsular sinus into the lymph node parenchyma following allergen exposure, synergizing with CCR7/CCL21 in a Src-kinase-dependent manner. CCL8 produced by CD169+SIGN-R1+ macrophages in interfollicular regions provides the CCR8 signal. In CCR8-deficient mice, CD301b+ DCs are trapped in the subcapsular sinus and cannot enter the parenchyma, resulting in defective Th2 differentiation.\",\n      \"method\": \"CCR8-/- mice, DC migration tracking by flow cytometry and imaging, CCL8 source identification, Src kinase inhibition, CCR7 expression analysis, Th2 differentiation assays\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — CCR8-/- genetic model with mechanistic pathway (Src kinase dependence, CCL8 source identification), multiple orthogonal readouts\",\n      \"pmids\": [\"30170811\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Activated ILC2s produce CCL1 and are a major CCL1 source in vivo; CCL1 signaling via CCR8 on ILC2s regulates their proliferation and capacity to protect against helminthic infections, establishing a CCR8-dependent autocrine/paracrine feed-forward loop for ILC2 self-renewal.\",\n      \"method\": \"In vitro CCR8 chemotaxis assay, in vivo CCR8-/- mouse models, CCL1 measurement by ELISA, helminth infection model, proliferation assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO mice with in vitro and in vivo functional validation, single lab\",\n      \"pmids\": [\"31537642\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CCR8 expression on Tregs was upregulated by TCR-mediated signaling in an NF-κB-dependent fashion. CCR8 was not essential for the recruitment, activation, or suppressive capacity of tumor-infiltrating Tregs per se, but ADCC-prone anti-CCR8 nanobody-Fc fusion proteins depleted ti-Tregs in an NK cell-dependent manner and elicited antitumor immunity synergizing with anti-PD-1.\",\n      \"method\": \"scRNA-seq, flow cytometry, NF-κB inhibition, nanobody generation, ADCC assay, NK cell depletion in vivo, LLC-OVA and MC38 tumor models\",\n      \"journal\": \"Journal for immunotherapy of cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal experiments including mechanistic NF-κB studies, ADCC mechanism, and in vivo NK cell dependence\",\n      \"pmids\": [\"33589525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Disruption of the CCL1-CCR8 axis (via CCL1 and Apoe double deficiency or anti-CCR8 blocking antibodies) promotes atherosclerosis by reducing Treg recruitment to the aorta, decreasing IL-10 levels, and shifting toward a Th1 response, establishing a protective role for CCL1-CCR8 in vascular inflammation.\",\n      \"method\": \"Ccl1/Apoe double-KO mice, flow chamber adhesion assay, intravital microscopy, anti-CCR8 blocking antibody, Treg quantification in aorta/spleen, cytokine measurement\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic and antibody-based approaches with multiple functional readouts, single lab\",\n      \"pmids\": [\"31121182\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CCR8 expression on tumor-infiltrating Tregs is upregulated by TCR stimulation but is not essential for their recruitment, activation, or suppressive function. Depletion of CCR8+ tumor Tregs via ADCC-capable anti-CCR8 antibody elicits antitumor immunity, reduces tumor growth, and synergizes with anti-PD-1 therapy without affecting peripheral Tregs.\",\n      \"method\": \"Fc-optimized anti-CCR8 antibody, CCR8-/- mouse tumors (MC38, B16), flow cytometry, ex vivo depletion in primary human tumor samples\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple tumor models, human ex vivo validation, mechanistic ADCC dependence demonstrated\",\n      \"pmids\": [\"33757978\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In bladder cancer, CCR8 expression in intratumoral Tregs maintains stability and potentiates suppressive function by upregulating transcription factors FOXO1 and c-MAF. CCR8 blockade destabilizes intratumoral Tregs into a fragile phenotype and reactivates antitumor immunity, augmenting anti-PD-1 benefits.\",\n      \"method\": \"Flow cytometry, ex vivo CCR8 blockade experiments, transcription factor analysis (FOXO1, c-MAF), TCGA bioinformatics, retrospective clinical cohort, anti-PD-1 combination\",\n      \"journal\": \"Cancer immunology, immunotherapy : CII\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — mechanistic follow-up on FOXO1/c-MAF pathway with ex vivo functional validation, single lab\",\n      \"pmids\": [\"32367308\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CCR8+ tumor Tregs are predominantly clonally expanded cells activated by tumor-associated antigens. Anti-CCR8 mAb treatment selectively eliminated these multiclonal tumor Tregs (sparing peripheral Tregs), expanded tumor-specific CD8+ T cells, and generated memory-type antitumor immunity without autoimmunity in mice.\",\n      \"method\": \"scRNA-seq, TCR clonotype analysis, CCR8-/- mice, anti-CCR8 mAb (depleting vs. non-depleting), flow cytometry, tumor rechallenge memory assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — scRNA-seq + clonotype analysis + mAb depletion across multiple tumor types with mechanistic memory studies\",\n      \"pmids\": [\"35140181\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Donor kidney-resident macrophages upregulate CCL8 upon transplantation, which promotes CCR8-expressing recipient T cell (CD4, CD8, γδ T cell) infiltration into kidney allografts. Blocking CCL8-CCR8 or depleting donor kidney resident macrophages significantly inhibited early allograft immune infiltration and improved allograft function.\",\n      \"method\": \"Murine allogeneic kidney transplant model, CCL8/CCR8 blockade, macrophage depletion, flow cytometry for immune infiltrates, allograft function assays\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo blockade and depletion experiments with functional organ outcome, single lab\",\n      \"pmids\": [\"35973731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Intracellular lactate upregulates CCR8 expression in CD4+ T cells and macrophages through histone H3K18 lactylation at the CCR8 gene promoter, linking tumor glycolysis to CCR8-expressing immunosuppressive Tregs in glioblastoma.\",\n      \"method\": \"ChIP assay for H3K18 lactylation at CCR8 promoter, luciferase reporter assay, RT-qPCR, western blot, flow cytometry, LDHA inhibitor (oxamate)\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — ChIP with reporter assay establishes epigenetic regulatory mechanism, single lab\",\n      \"pmids\": [\"37770937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Tumor-derived exosomes promote CCL1 secretion by lung fibroblasts, which activates CCR8 on T cells to drive Treg differentiation and establish an immunologically tolerant pre-metastatic niche. Inhibiting CCL1-CCR8 axis with AZ084 suppressed Treg differentiation and tumor metastasis in the lung.\",\n      \"method\": \"LLC-exo in vitro co-culture, CCL1 ELISA, CCR8 flow cytometry, AZ084 CCR8 antagonist, GW4869 exosome inhibitor, in vivo pre-metastatic niche mouse model\",\n      \"journal\": \"Cancer immunology, immunotherapy : CII\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological blockade with in vitro and in vivo readouts, single lab\",\n      \"pmids\": [\"35428909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TNF-α in the colorectal cancer microenvironment upregulates CCR8 expression in Tregs via TNFR2/NF-κB signaling and the FOXP3 transcription factor. PD-1 blockade induces additional CCR8+ Treg infiltration; TNFR2 depletion or blockade suppresses tumor progression by reducing CCR8+ Treg infiltration.\",\n      \"method\": \"NF-κB/TNFR2 inhibition, FOXP3 ChIP, Tnfr2-/- mouse tumor models, anti-PD-1 combination, flow cytometry\",\n      \"journal\": \"Journal of molecular cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic and pharmacological dissection of upstream regulatory pathway, single lab\",\n      \"pmids\": [\"37935468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Small molecule CCR8 agonists (ZK756326, AZ6, vCCL1) display biased signaling relative to human CCL1: while all induce full agonist calcium mobilization, Gβγ signaling is required for CCL1-induced but not small molecule agonist-induced cell migration. Small molecule agonists show higher efficacy for β-arrestin 1 recruitment, which occurs independently of Gαi signaling.\",\n      \"method\": \"Calcium mobilization, cellular impedance (xCELLigence), cell migration assay, β-arrestin 1/2 recruitment assay, Gβγ inhibitor (gallein), Gαi inhibitor (pertussis toxin)\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with multiple signaling pathway inhibitors across multiple assays; single lab\",\n      \"pmids\": [\"33872569\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CCR8+ Tregs are specifically enriched in human first-trimester decidua, produced in part through CCL1 secreted by decidual CD49a+ NK cells. Depletion of CCR8+ dTregs increased fetal loss susceptibility with altered decidual immune profiles; adoptive transfer of CCR8+ Tregs rescued fetal loss in abortion-prone mice, establishing a CCR8+ Treg subset as essential for maternal-fetal tolerance.\",\n      \"method\": \"scRNA-seq, TCR sequencing, CCR8+ dTreg depletion in mice, adoptive transfer rescue experiments, CCL1 ELISA, flow cytometry\",\n      \"journal\": \"Science immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — scRNA-seq + depletion + adoptive transfer establishing causal role of CCR8+ Tregs in maternal tolerance\",\n      \"pmids\": [\"40249828\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CCR8 is a Gi-coupled seven-transmembrane chemokine receptor whose primary endogenous ligand is CCL1 (I-309), with additional ligands including CCL8 and CCL18; upon ligand binding it signals through Gαi (pertussis toxin-sensitive), activates the RAS/MAPK/ERK pathway to suppress apoptosis, and recruits β-arrestins for internalization, with tyrosine sulfation at the N-terminal Y14/Y15 residues critical for CCL1 binding; CCR8 is selectively expressed on Th2 cells, a subset of CD4+CD25+FOXP3+ regulatory T cells, dendritic cell subsets, monocytes/macrophages, and thymocytes, where it directs cell trafficking and—on tumor-infiltrating Tregs whose CCR8 expression is driven by TCR/NF-κB and TNFR2/NF-κB signals—mediates potent immunosuppression that can be therapeutically targeted by ADCC-capable anti-CCR8 antibodies to selectively deplete tumor Tregs and restore antitumor immunity.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CCR8 is a Gαi-coupled CC chemokine receptor that directs immune cell trafficking, survival, and immunosuppressive function across diverse tissue contexts. Its primary endogenous ligands are CCL1, CCL8, and CCL18, which bind an N-terminal domain requiring tyrosine sulfation at Y14/Y15; ligand engagement activates pertussis toxin-sensitive Gαi signaling, the RAS/MAPK/ERK anti-apoptotic pathway, STAT3-dependent enhancement of Treg suppressive programs (FOXP3, CD39, IL-10, granzyme B), and β-arrestin-mediated receptor internalization [PMID:9211859, PMID:12645948, PMID:28533380, PMID:17023422, PMID:14736884]. CCR8 is preferentially expressed on Th2 cells, FOXP3+ regulatory T cells, dendritic cell subsets, ILC2s, monocytes/macrophages, and thymocytes, where it mediates chemotaxis to sites of allergic inflammation, helminth defense, and tissue homeostasis; in the tumor microenvironment, CCR8 expression is driven by TCR/NF-κB and TNFR2/NF-κB signaling and marks clonally expanded tumor-antigen-reactive Tregs whose selective depletion by ADCC-competent anti-CCR8 antibodies restores antitumor immunity and generates immunological memory without systemic autoimmunity [PMID:9670926, PMID:11560999, PMID:21217759, PMID:35140181, PMID:33757978, PMID:33589525, PMID:37935468]. CCR8 also serves as an HIV-1 co-receptor on thymocytes and T cells and is exploited by viral chemokine mimics encoded by HHV-8 (vMIP-I agonist) and molluscum contagiosum virus (MC148 antagonist) [PMID:9417093, PMID:10419462, PMID:10620615].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Deorphanization of CCR8 established it as the specific Gαi-coupled receptor for CCL1 (I-309), resolving the ligand identity and G-protein coupling for this orphan seven-transmembrane receptor.\",\n      \"evidence\": \"Transfection of CCR8 into pre-B cells conferred CCL1-dependent calcium flux (EC50 ~2 nM) and chemotaxis blocked by pertussis toxin; radioligand binding measured Kd ~1.2 nM\",\n      \"pmids\": [\"9211859\", \"9207005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural information on CCR8-CCL1 complex\", \"Endogenous expression levels on primary cells not quantified\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"CCR8 was shown to be preferentially expressed on Th2-polarized T cells and to function as an HIV-1 co-receptor, defining its dual roles in adaptive immunity and viral pathogenesis.\",\n      \"evidence\": \"Northern blot/RT-PCR on polarized T cells; HIV-1 envelope-mediated fusion and infection assays in CCR8-transfected and primary thymocyte systems\",\n      \"pmids\": [\"9670926\", \"9417093\", \"9480837\", \"9820476\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of CCR8 for HIV-1 tropism in patients not established\", \"Mechanism of Th2-selective expression unknown\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Viral chemokine mimics from HHV-8 (vMIP-I as agonist, vMIP-II as antagonist) and identification of MC148 as a highly selective CCR8 antagonist provided pharmacological tools and revealed that viruses exploit or block CCR8 to modulate host immunity.\",\n      \"evidence\": \"Comprehensive competitive binding across 65 chemokines, calcium mobilization, and chemotaxis assays in transfected cells and primary T cells\",\n      \"pmids\": [\"10419462\", \"10377196\", \"10620615\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo role of viral chemokine mimicry in HHV-8 or MCV pathogenesis not directly tested\", \"Structural basis of vMIP-I agonism vs. MC148 antagonism unknown\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Discovery that CCR8 marks CD4+CD25+ regulatory T cells and mediates their chemotaxis to CCL1 established the receptor as a key Treg surface marker and functional trafficking receptor.\",\n      \"evidence\": \"Flow cytometry and chemotaxis of sorted CD4+CD25+ vs CD25− T cells; functional alloproliferation assays\",\n      \"pmids\": [\"11560999\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CCR8 signaling has intrinsic effects on Treg suppressive function or only on migration was unresolved\", \"CCR8 expression heterogeneity within Treg subsets not characterized\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"CCR8 was shown to activate the RAS/MAPK/ERK pathway to suppress apoptosis, establishing a survival signaling function beyond chemotaxis.\",\n      \"evidence\": \"Pertussis toxin, MEK inhibitor PD98059, dominant negative M-RAS, and MC148 antagonist all blocked CCL1/vMIP-I anti-apoptotic activity in thymic lymphoma cells\",\n      \"pmids\": [\"12645948\", \"12525579\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological significance of CCR8 anti-apoptotic signaling in primary thymocyte selection not established\", \"Downstream effectors of ERK in this context not identified\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Structure-function analysis revealed that N-terminal tyrosine sulfation (Y14/Y15) is essential for CCL1 binding, establishing the molecular determinants of ligand recognition.\",\n      \"evidence\": \"Systematic site-directed mutagenesis (Tyr→Phe, Asn→Gln, Thr/Ser→Ala) with flow cytometry and calcium flux readouts; Y14F/Y15F double mutant was essentially inactive\",\n      \"pmids\": [\"14736884\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No crystal or cryo-EM structure of sulfated CCR8\", \"Whether tyrosine sulfation is regulated in vivo as a signaling switch is unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"CCR8 internalization was shown to be β-arrestin 1/2-dependent and Gαi-independent, and Glu-286 in TM7 was identified as a critical residue for both receptor trafficking and small-molecule agonist binding, dissecting G-protein and arrestin signaling arms.\",\n      \"evidence\": \"β-arrestin overexpression/depletion, site-directed mutagenesis of Glu286, calcium flux, chemotaxis, and internalization assays\",\n      \"pmids\": [\"17023422\", \"17652183\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biased signaling consequences for Treg biology not explored\", \"Full agonist binding pocket model incomplete\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"In vivo studies using CCR8-deficient mice established that mast cell-derived CCL1 signals through CCR8 on CD4+ T cells to orchestrate allergic airway inflammation, and that CCR8 on macrophages drives peritoneal adhesion formation.\",\n      \"evidence\": \"CCR8−/− mice, mast cell-deficient mice, CCL1 neutralization, adenoviral CCL1 restoration, airway hyperresponsiveness; anti-CCL1/CCR8−/− adhesion models\",\n      \"pmids\": [\"17641040\", \"17404314\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of CCR8 on T cells vs. macrophages vs. DCs in airway inflammation unresolved\", \"CCR4 was later shown to be more critical for Th2 lung entry\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identification of mouse CCL8 as a second endogenous CCR8 agonist driving Th2-mediated eosinophilic skin inflammation resolved a species-specific ligand difference and expanded the CCR8 ligand repertoire.\",\n      \"evidence\": \"Ccr8−/− and Ccl8−/− mice in chronic atopic dermatitis model; receptor binding and calcium flux confirmed CCL8 selectivity for CCR8 over CCR2\",\n      \"pmids\": [\"21217759\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether human CCL8 acts similarly on human CCR8 not established\", \"Role of CCL8-CCR8 beyond skin unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"CCL18 was identified as a third endogenous human CCR8 ligand, broadening the receptor's physiological ligand repertoire.\",\n      \"evidence\": \"CCR8 transfection, competitive binding, calcium flux, internalization, cross-desensitization with CCL1, and CCR8−/− mouse Th2 cell migration\",\n      \"pmids\": [\"23999500\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of CCL18 vs. CCL1 in different tissues not determined\", \"CCL18 has no mouse ortholog, complicating in vivo validation\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"CCL1-CCR8 signaling was found to enhance Treg suppressive function via STAT3-dependent upregulation of FOXP3, CD39, IL-10, and granzyme B, and an autocrine CCL1 loop was discovered, shifting the view of CCR8 from a mere trafficking receptor to a direct modulator of Treg immunosuppressive programs.\",\n      \"evidence\": \"STAT3 inhibition, CCL1-Ig administration, CCR8−/− adoptive transfer in EAE model, flow cytometry for effector molecules\",\n      \"pmids\": [\"28533380\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether STAT3 activation is direct or indirect not resolved\", \"STAT3 vs. ERK pathway integration in Tregs unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"CCR8 was shown to guide CD301b+ dendritic cell migration from the subcapsular sinus into lymph node parenchyma via Src-kinase signaling, establishing a non-T-cell function for CCR8 in initiating Th2 immunity.\",\n      \"evidence\": \"CCR8−/− mice, DC migration tracking by imaging and flow cytometry, Src kinase inhibition, CCL8 source identification in CD169+ macrophages\",\n      \"pmids\": [\"30170811\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CCR8 functions similarly in human lymph nodes not tested\", \"Molecular details of CCR7-CCR8 synergy mechanism unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"CCR8 was identified as a therapeutic target on tumor-infiltrating Tregs: its expression is driven by TCR/NF-κB signaling, it marks tumor-specific Tregs, and ADCC-competent anti-CCR8 antibodies selectively deplete tumor Tregs to restore antitumor immunity without autoimmunity.\",\n      \"evidence\": \"scRNA-seq, NF-κB inhibition, nanobody-Fc ADCC assays, NK cell depletion, LLC-OVA and MC38 tumor models, anti-PD-1 synergy\",\n      \"pmids\": [\"33589525\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"CCR8 signaling was shown dispensable for Treg suppressive function in this study, contrasting STAT3/FOXP3 findings from 2017\", \"Human clinical validation of anti-CCR8 therapy pending\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"CCR8+ tumor Tregs were demonstrated to be clonally expanded, tumor-antigen-reactive cells whose antibody-mediated depletion generates durable antitumor memory, and epigenetic regulation of CCR8 expression via histone H3K18 lactylation was discovered linking tumor metabolism to immunosuppression.\",\n      \"evidence\": \"scRNA-seq with TCR clonotype analysis; anti-CCR8 mAb depletion with tumor rechallenge; ChIP for H3K18 lactylation at CCR8 promoter with reporter assay and LDHA inhibitor\",\n      \"pmids\": [\"35140181\", \"37770937\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether lactylation-driven CCR8 upregulation is reversible therapeutically not tested\", \"Relative contribution of NF-κB vs. lactylation vs. TNFR2 pathways in different tumor types unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"TNFR2/NF-κB signaling was identified as an additional upstream pathway driving CCR8 expression in tumor Tregs, with FOXP3 directly binding the CCR8 promoter, and PD-1 blockade was found to paradoxically increase CCR8+ Treg infiltration.\",\n      \"evidence\": \"NF-κB/TNFR2 inhibition, FOXP3 ChIP, Tnfr2−/− tumor models, anti-PD-1 combination studies\",\n      \"pmids\": [\"37935468\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether TNFR2 blockade combined with anti-CCR8 provides additive benefit is untested\", \"Mechanism of PD-1 blockade-induced CCR8+ Treg expansion unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"CCR8+ Tregs were shown to be essential for maternal-fetal immune tolerance, with decidual NK cell-derived CCL1 recruiting CCR8+ dTregs whose depletion caused fetal loss and whose adoptive transfer rescued it.\",\n      \"evidence\": \"scRNA-seq, TCR sequencing, CCR8+ dTreg depletion and adoptive transfer in abortion-prone mice, CCL1 source identification\",\n      \"pmids\": [\"40249828\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CCR8 signaling modulates dTreg suppressive programs or only trafficking is unclear\", \"Human translational relevance for recurrent pregnancy loss not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: whether CCR8 signaling intrinsically enhances Treg suppressive function (conflicting evidence from STAT3 studies vs. dispensability findings), the structural basis of ligand selectivity and biased agonism, and whether anti-CCR8 antibody therapy achieves durable clinical responses in human cancers.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No high-resolution structure of CCR8 bound to any ligand\", \"Conflicting reports on whether CCR8 signaling is required for Treg suppressive function vs. serving only as a depletion marker\", \"No published human clinical efficacy data for anti-CCR8 therapy\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 1, 7, 8, 27]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [14, 29, 35]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 16, 17, 19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0162582\", \"supporting_discovery_ids\": [0, 14, 19, 29, 41]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 12, 22, 25, 29, 32, 34, 36]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [5, 6, 10]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"CCL1\",\n      \"CCL8\",\n      \"CCL18\",\n      \"ARRB1\",\n      \"ARRB2\",\n      \"GNAI1\",\n      \"FOXP3\",\n      \"STAT3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}