Reduced chemokine C-C motif ligand 1 expression may negatively regulate colorectal cancer progression at liver metastatic sites

Colorectal cancer (CRC) liver metastasis, albeit a stage-IV disease, is completely curable by surgical resection in selected patients. In addressing the molecular basics of this phenomenon, differentially expressed genes at primary and liver metastatic sites were screened by RNA sequencing with the use of paraffin-embedded surgical specimens. Chemokine C-C motif ligand 1 (CCL1), a chemotactic factor for a ligand of the chemokine C-C motif receptor 8 (CCR8), was isolated as one of the differentially expressed genes. Histological analysis revealed that the number of CCL1-positive cells, mainly tumour associated macrophages (TAMs) located in the stroma of CRC, decreased significantly at liver metastatic sites, while the expression level of CCR8 on CRC remained unchanged. To explore the biological significance of the CCL1-CCR8 axis in CRC, CCR8-positive CRC cell line Colo320DM was used to assess the effect of the CCL1-CCR8 axis on major signalling pathways, epithelial mesenchymal transition induction and cell motility. Upon stimulation of recombinant CCL1 (rCCL1), phosphorylation of AKT was observed in Colo320DM cells; on the other hand, the corresponding significant increase in MMP-2 levels demonstrated by RT-qPCR was nullified by siRNA (siCCR8). In the scratch test, rCCL1 treatment significantly increased the motility of Colo320DM cells, which was similarly nullified by siCCR8. Thus, the activation of the CCL1-CCR8 axis is a positive regulator of CRC tumour progression. Reduced CCL1 expression of TAMs at liver metastatic sites may partly explain the unique slow tumour progression of CRC, thus providing for a grace period for radical resection of metastatic lesions.

Metformin-induced reduction of CCR8 enhances the anti-tumor immune response of PD-1 immunotherapy in glioblastoma

Immunotherapy strategies targeting the programmed cell death 1 (PD-1) in clinical treatments have shown limited success in controlling glioblastoma malignancies. Metformin exserts antitumor function, yet the underlying mechanisms remain unclear. Here, we investigated whether metformin could enhance the effectiveness of anti-PD-1 therapy by activating the immune system. Whether combination of an anti-PD-1 antibody or not, metformin significantly increased tumor-infiltrating CD4+ T cells while decreased regulatory T (Treg) cells in a mouse GBM model. Additionally, metformin reduced CC motif chemokine receptor CCR8 and elevated Interleukin 17 A (IL-17 A) expressions. Mechanistically, metformin reduces histone acetylation at the CCR8 promotor and inhibits CCR8 expression by upregulating AMP-activated protein kinase (AMPK)-activated sirtuin 2 (SIRT2). Metformin enhances the effectiveness of anti-PD-1 immunotherapy by reducing CCR8 expression on tumor-infiltrating Treg cells, suggesting that metformin has an antitumor effect by alleviating immunosuppression and promoting T cell-mediated immune response.

Development of a cellular model to study CCR8 signaling in tumor-infiltrating regulatory T cells

The human CC chemokine receptor 8 (CCR8) is specifically expressed on tumor-infiltrating regulatory T cells (TITRs) and is a promising drug target for cancer immunotherapy. However, the role of CCR8 signaling in TITR biology and the effectiveness of CCR8 small molecule antagonists as TITR-targeting immunotherapy remain subjects of ongoing debate. In this work, we generated a novel cellular model of TITRs by culturing peripheral blood mononuclear cell-derived regulatory T cells in medium containing tumor cell-conditioned medium, CD3/CD28 activator, interleukin-2 and 1α,25-dihydroxyvitamin D3. This cellular model (named TITR mimics) highly and stably expressed a series of TITR signature molecules, including CCR8, FOXP3, CD30, CD39, CD134, CD137, TIGIT and Tim-3. Moreover, TITR mimics displayed robust in vitro immunosuppressive activity. To unravel the functional role of CCR8 in TITR mimics, a chemotaxis assay was performed showing strong and CCR8-specific migration toward CCL1, the natural chemokine agonist of CCR8. However, either stimulation (with CCL1) or blocking (with the small molecule antagonist NS-15) of CCR8 signaling did not affect the immunosuppressive activity, proliferation and survival of TITR mimics. Collectively, our work provides a method for the generation of TITR mimics in vitro, which can be used to study TITR biology and to evaluate drug candidates targeting TITRs. Furthermore, our findings suggest that CCR8 signaling primarily regulates migration of these cells.

MiR-184-5p represses neuropathic pain by regulating CCL1/CCR8 signaling interplay in the spinal cord in diabetic mice

BACKGROUND

Diabetic neuropathic pain (DNP) is a serious complication for diabetic patients involving nervous system. MicroRNAs (miRNAs) are small-noncoding RNAs which are dysregulated in neuropathic pain, and might be critical molecules for pain treatment. Our previous study has shown miR-184-5p was significantly downregulated in DNP. Therefore, the mechanism of miR-184-5p in DNP was investigated in this study.

METHODS

A DNP model was established through streptozotocin (STZ). The pharmacological tools were injected intrathecally, and pain behavior was evaluated by paw withdrawal mechanical thresholds (PWMTs). Bioinformatics analysis, Dual-luciferase reporter assay and fluorescence-in-situ-hybridization (FISH) were used to seek and confirm the potential target genes of miR-184-5p. The expression of relative genes and proteins was analyzed by quantitative reverse transcriptase real-time PCR (qPCR) and western blotting.

RESULTS

MiR-184-5p expression was down-regulated in spinal dorsal on days 7 and 14 after STZ, while intrathecal administration of miR-184-5p agomir attenuates neuropathic pain induced by DNP and intrathecal miR-184-5p antagomir induces pain behaviors in naïve mice. Chemokine CC motif ligand 1 (CCL1) was found to be a potential target of miR-184-5p and the protein expression of CCL1 and the mRNA expression of CCR8 were up-regulated in spinal dorsal on days 7 and 14 after STZ. The luciferase reporter assay and FISH demonstrated that CCL1 is a direct target of miR-184-5p. MiR-184-5p overexpression attenuated the expression of CCL1/CCR8 in DNP; intrathecal miR-184-5p antagomir increased the expression of CCL1/CCR8 in spinal dorsal of naïve mice.

CONCLUSION

This research illustrates that miR-184-5p alleviates DNP through the inhibition of CCL1/CCR8 signaling expression.

CD4+CCR8+ Tregs in ovarian cancer: a potential effector Tregs for immune regulation

BACKGROUND

Tregs are key drivers of immunosuppression in solid tumors. As an important chemokine receptor on Tregs, the regulatory effect of CCR8 on tumor immunity has received more and more attention. However, the current research on CCR8 in the immune microenvironment of ovarian cancer has not been clear.

METHODS

Bioinformatics analysis was used to compare the transcriptome differences between CD4+ T cells in the peripheral circulation and infiltrated in ovarian tumor tissues. RT-PCR was used to detect the expression levels of chemokine receptor-related differential genes on CD4+ T cells in peripheral blood and ovarian tumor tissues. Multiparameter flow cytometry was used to detect the proportion and phenotypic characteristics of CD4+CCR8+ Tregs and CD4+CCR8- Tregs in different sample types. The expression level of CCR8 ligands was detected at multiple levels. To explore the important role of CCR8-CCL1 and CCR8-CCL18 axis in the migration and invasion of CD4+CCR8+ Tregs into ovarian tumor tissues by establishing a chemotaxis system in vitro.

RESULTS

In this study, significantly different gene expression profiles were found between peripheral circulating CD4+ T cells and infiltrating CD4+ T cells in ovarian tumor tissues, in which chemokine-chemokine receptor signaling pathway was significantly enriched in all three groups of differential genes. The expression level of CCR8 in infiltrating CD4+ T cells of ovarian cancer tissue was significantly higher than that in peripheral blood of healthy controls and ovarian cancer patients, and high expression of CCR8 was significantly correlated with advanced tumor stage and poor differentiation. CD4+CCR8+ Tregs are the main type of infiltrating CD4+ Tregs in ovarian tumor tissues, which have stronger immunosuppressive phenotypes, secrete more inhibitory cytokines and have stronger proliferation ability. The ligands CCL1 and CCL18 corresponding to CCR8 were significantly overexpressed in ovarian tumor tissues, and the CCR8-CCL1 and CCR8-CCL18 axis played a key role in the migration and infiltration of CD4+CCR8+ Tregs into ovarian tumor tissues.

CONCLUSIONS

The results of this study may help to understand the phenotypic characteristics and recruitment process of Tregs in the tumor, and provide new ideas for improving the immunosuppressive status of the ovarian cancer microenvironment.

Blockade of TNF-α/TNFR2 signalling suppresses colorectal cancer and enhances the efficacy of anti-PD1 immunotherapy by decreasing CCR8+ T regulatory cells

Enrichment of regulatory T cells (Tregs) in the tumour microenvironment (TME) has been recognized as one of the major factors in the initiation and development of resistance to immune checkpoint inhibitors. C-C motif chemokine receptor 8 (CCR8), a marker of activated suppressive Tregs, has a significant impact on the functions of Tregs in the TME. However, the regulatory mechanism of CCR8 in Tregs remains unclear. Here, we reveal that a high level of TNF-α in the colorectal cancer (CRC) microenvironment upregulates CCR8 expression in Tregs via the TNFR2/NF-κB signalling pathway and the FOXP3 transcription factor. Furthermore, in both anti-PD1-responsive and anti-PD1-unresponsive tumour models, PD1 blockade induced CCR8+ Treg infiltration. In both models, Tnfr2 depletion or TNFR2 blockade suppressed tumour progression by reducing CCR8+ Treg infiltration and thus augmented the efficacy of anti-PD1 therapy. Finally, we identified that TNFR2+CCR8+ Tregs but not total Tregs are positively correlated with adverse prognosis in CRC and gastric cancer. Our work reveals the regulatory mechanisms of CCR8 in Tregs and identifies TNFR2 as a promising target for immunotherapy.

Synthesis and structure-activity relationship study of phenoxybenzylpiperazine analogues as CCR8 agonists

CCR8 agonists hold promise for the treatment of various auto-immune diseases. Despite the fact that phenoxybenzylpiperazine derivatives are known to be endowed with CCR8 agonistic activity, systematic structure-activity relationship studies have not been reported. In this study, ZK756326, a previously disclosed CCR8 agonist, was divided in various fragments and each subunit was subjected to structural modifications. All newly synthesized analogues were evaluated in a CCR8 calcium mobilization assay, revealing that only limited structural variation was tolerated in both phenyl rings and at the benzylic position. In contrast, various linkers gave analogues with good CCR8 agonistic potency. In addition, the presence of small substituents on the piperazinyl moiety or the exchange of the piperazinyl for a piperidinyl group afforded compounds with promising CCR8 agonism, with the most potent congener being 10-fold more potent than ZK756326.

Oxamate enhances the efficacy of CAR-T therapy against glioblastoma via suppressing ectonucleotidases and CCR8 lactylation

BACKGROUND

Chimeric antigen receptor (CAR)-T immunotherapy fails to treat solid tumors due in part to immunosuppressive microenvironment. Excess lactate produced by tumor glycolysis increases CAR-T immunosuppression. The mechanism of lactate inducing the formation of immunosuppressive microenvironment remains to be further explored.

METHODS

Immunocyte subpopulations and molecular characteristics were analyzed in the orthotopic xenografts of nude mice using flow cytometry assay and immunohistochemical staining after oxamate, a lactate dehydrogenase A (LDHA) inhibitor, and control T or CAR-T cells injection alone or in combination. RT-qPCR, western blot, flow cytometry, immunofluorescence, luciferase reporter assay, chromatin immunoprecipitation and ELISA were performed to measure the effect of lactate on the regulation of CD39, CD73 and CCR8 in cultured glioma stem cells, CD4 + T cells or macrophages.

RESULTS

Oxamate promoted immune activation of tumor-infiltrating CAR-T cells through altering the phenotypes of immune molecules and increasing regulatory T (Treg) cells infiltration in a glioblastoma mouse model. Lactate accumulation within cells upregulated CD39, CD73 and CCR8 expressions in both lactate-treated cells and glioma stem cells-co-cultured CD4 + T cells and macrophages, and intracellular lactate directly elevated the activities of these gene promotors through histone H3K18 lactylation.

CONCLUSIONS

Utilizing lactate generation inhibitor not only reprogramed glucose metabolism of cancer stem cells, but also alleviated immunosuppression of tumor microenvironment and reduced tumor-infiltrating CAR-Treg cells, which may be a potential strategy to enhance CAR-T function in glioblastoma therapy.

A Novel Prognostic Biomarker CCR8 for Gastric Cancer and Anti-CCR8 Blockade Attenuate the Immunosuppressive Capacity of Tregs In Vitro

Objective: To investigate the immunotherapeutic roles and functions of C-C Motif Chemokine Receptor 8 (CCR8) molecule in gastric cancer (GC). Materials and Methods: Clinicopathological features of 95 GC cases were collected by a follow-up survey. The expression level of CCR8 was measured by immunohistochemistry (IHC) staining and analyzed with the cancer genome atlas database. The relationship between CCR8 expression and Clinicopathological features of GC cases was evaluated by univariate and multivariate analysis. Flow cytometry was used to determine the expression of cytokines and the proliferation of CD4+ regulator T cells (Tregs) and CD8+ T cells. Results: An upregulated expression of CCR8 in GC tissues was associated with tumor grade, nodal metastasis, and overall survival (OS). Tumor-infiltrated Tregs with higher expression of CCR8 produced more IL10 molecules in vitro. In addition, anti-CCR8 blocking downregulated IL10 expression produced by CD4+ Tregs, and reversed the suppression by Tregs on the secretion and proliferation of CD8+ T cells. Conclusion: CCR8 molecule could be a prognostic biomarker for GC cases and a therapeutic target for immune treatments.

TGF-β broadly modifies rather than specifically suppresses reactivated memory CD8 T cells in a dose-dependent manner

Transforming growth factor β (TGF-β) directly acts on naïve, effector and memory T cells to control cell fate decisions, which was shown using genetic abrogation of TGF-β signaling. TGF-β availability is altered by infections and cancer, however the dose-dependent effects of TGF-β on memory CD8 T cell (Tmem) reactivation are still poorly defined. We examined how activation and TGF-β signals interact to shape the functional outcome of Tmem reactivation. We found that TGF-β could suppress cytotoxicity in a manner that was inversely proportional to the strength of the activating TCR or pro-inflammatory signals. In contrast, even high doses of TGF-β had a comparatively modest effect on IFN-γ expression in the context of weak and strong reactivation signals. Since CD8 Tmem may not always receive TGF-β signals concurrently with reactivation, we also explored whether the temporal order of reactivation versus TGF-β signals is of importance. We found that exposure to TGF-β prior to as well as after an activation event were both sufficient to reduce cytotoxic effector function. Concurrent ATAC-seq and RNA-seq analysis revealed that TGF-β altered ~10% of the regulatory elements induced by reactivation and also elicited transcriptional changes indicative of broadly modulated functional properties. We confirmed some changes on the protein level and found that TGF-β-induced expression of CCR8 was inversely proportional to the strength of the reactivating TCR signal. Together, our data suggest that TGF-β is not simply suppressing CD8 Tmem, but modifies functional and chemotactic properties in context of their reactivation signals and in a dose-dependent manner.

Expression of CCR8 and CCX-CKR on Basophils in Chronic Urticaria Is Amplified by IgE-Mediated Activation

Recruitment to the local tissue and alerted phenotype are the hallmarks of basophils in chronic urticaria (CU). Chemokine receptors such as chemokine (C-C motif) receptor 4 (CCR4) or CCR8 have been studied in skin diseases, e.g., atopic dermatitis, but not in CU. In this study, we aimed to define CU's basophil homing potential and receptor profile and the effect of Omalizumab treatment on these. Unstimulated and activated (anti-IgE, fMLP, C5a, and Substance P) whole blood basophils from 11 Omalizumab-treated CU patients and 10 healthy subjects were investigated with flow cytometry. Unstimulated basophils in CU showed higher expression of the skin-associated (CCR8) and scavenger (CCX-CKR) receptors and lower expression of the lung-associated (CCR3) receptor in contrast to healthy ones. IgE-mediated activation increased the percentage of CCR8 and CCX-CKR in CU compared to healthy group and elevated the expression of the lung-associated chemokine receptor, XCR1, in all groups. A trend of augmented expression of the coagulation cascade (CD87) and fMLP (FPR1) receptors was seen on basophils in CU, while a tendency of reduced expression was seen for itch (IL-31RA) and immunotolerance (CD109) receptors. fMLP and C5a increased the expression of CCR4, CCR8, CCX-CKR, and CD87 and decreased CCR2 and CCR3, though no changes between the groups were found. In conclusion, CU basophils exhibit skin-homing potential amplified by IgE-mediated stimulation.

The chemokine CCL1 facilitates pulmonary fibrosis by promoting macrophage migration and M2 polarization

Macrophage M2 polarization has been identified in the pathogenesis of pulmonary fibrosis (PF), but the mediators that drive the macrophage M2 program in PF need to be clarified. We showed that the expression of AMFR and CCR8, two known receptors of CCL1, was increased in macrophages from lungs of mice with bleomycin (BLM)-induced PF. Deficiency in either AMFR or CCR8 in macrophages protected mice from BLM-induced PF. In vitro experiments revealed that CCL1 recruited macrophages by binding to its classical receptor CCR8 and drove the macrophage M2 phenotype via its interaction with the recently identified receptor AMFR. Mechanistic studies revealed that the CCL1-AMFR interaction enhanced CREB/C/EBPβ signaling to promote the macrophage M2 program. Together, our findings reveal that CCL1 acts as a mediator of macrophage M2 polarization and could be a therapeutic target in PF.

Development of an Anti-Mouse CCR8 Monoclonal Antibody (C8Mab-1) for Flow Cytometry and Immunocytochemistry

It has been widely accepted that monoclonal antibody (mAb) is an effective tool for cancer immunotherapy. The C-C motif chemokine receptor 8 (CCR8) is highly expressed in regulatory T cells and many cancers and is associated with the progression of the cancers. However, its role in cancer progression remains unclear. Thus, the development of mAbs for CCR8 leads to cancer immunotherapy and elucidation of unknown mechanisms of CCR8-dependent cancer progression. In this study, we have developed an anti-mouse CCR8 (mCCR8) mAb (clone C₈Mab-1, rat IgG_2a, kappa) using the Cell-Based Immunization and Screening (CBIS) method. We showed that C₈Mab-1 and its recombinant antibody (recC₈Mab-1) bind to mCCR8-overexpressed Chinese hamster ovary (CHO)-K1 cells (CHO/mCCR8), but not to the parental CHO-K1 cells, in flow cytometry and immunofluorescence. Moreover, C₈Mab-1 and recC₈Mab-1 specifically reacted to P388 (a mouse lymphocyte-like cells) and J774-1 (a mouse macrophage-like cells), which express endogenous mCCR8, in both applications. These results suggest that C₈Mab-1, developed using the CBIS method, is useful for flow cytometry and immunocytochemistry against exogenous and endogenous mCCR8.

Vaccination with a shared oncogenic tumor-self antigen elicits a population of CD8+ T cells with a regulatory phenotype

Cancer immunotherapy is a powerful tool for inducing antigen-specific antitumor cytotoxic T lymphocytes (CTLs). Next-generation strategies may include vaccination against overexpressed oncogenic tumor-self antigens. Previously, we reported vaccination against the oncogenic tumor-self antigen D52 (D52) was effective in preventing tumor growth. We recently reported that D52-vaccinated IL-10-deficient mice generated a significant memory response against tumor recurrence compared to wild-type mice and that vaccine-induced CD8+ IL-10+ T cells may possess regulatory function. Herein, we extended these studies by testing the hypothesis that D52-vaccine-elicited CD8+ IL-10+ T cells represent a distinct T cell population with a regulatory phenotype. C57Black/6J mice deficient in IL-10 or IFN-γ were vaccinated with the murine orthologue of D52; vaccination of wild-type (wt) mice served as a control for comparison. T cells were isolated from all three groups of vaccinated mice, and RNA was extracted from purified CD8+ T cells for deep sequencing and expression analysis. Chemokine receptor 8 (CCR8) and inducible co-stimulator (ICOS) were overexpressed in CD8+ T cells that produced IL-10 but not IFN-γ. These surface markers are associated with IL-10 producing CD4+ T regulatory cells thus supporting the possibility that CD8+ IL-10+ T cells elicited by D52 vaccination represent a unique regulatory T cell subset. The current phenotypic analyses of D52 vaccine elicited CD8+ T cells strengthen our premise that CD8+ IL-10+ T cells elicited by D52 tumor-self protein vaccination likely contribute to the suppression of memory CTL responses and inhibition of durable tumor immunity.

Inhibition of CCR8 attenuates Ang Ⅱ-induced vascular smooth muscle cell injury by suppressing the MAPK/NF-κB pathway

OBJECTIVES

Hyperinsulinemia, secondary to insulin resistance, may lead to vascular smooth muscle cell dysfunction. In the present research, we aimed to investigate the effect of Chemokine receptor 8 (CCR8) on angiotensin II (Ang II)-induced dysfunction of vascular smooth muscle cells (VSMCs) and to explore the underlying molecular mechanism.

MATERIALS AND METHODS

The expression of CCR8 was analyzed in diabetics and normal people by RT-PCR and ELISA. CCK-8 assay and transwell were used to explore cell proliferation and migration, and ELISA was used to measure the content of IL-6 and TNF-α. Reactive oxygen species (ROS) kit was employed to measure ROS generation.

RESULTS

The results revealed that CCR8 was highly expressed in diabetics and Ang Ⅱ-induced VSMCs. Further studies found that interfering with the expression of CCR8 significantly reduced the production of ROS and the levels of inflammatory factors in AngⅡ-induced VSMCs. Interfering with CCR8 increased the glucose uptake induced by AngⅡ+IR. More importantly, inhibition of CCR8 alleviated Ang II-induced dysfunction of VSMCs. Inhibition of CCR8 inactivated the MAPK/NF-κB signaling pathway.

CONCLUSION

Inhibition of CCR8 attenuates Ang II-induced VSMCs injury by inhibiting the MAPK/NF-κB pathway. CCR8 may be a new biomarker related to hypertension and insulin resistance and is a new target for the treatment of human cardiovascular diseases.

Inhibition of CCR8 attenuates Ang Ⅱ-induced vascular smooth muscle cell injury by suppressing the MAPK/NF-κB pathway

Objective(s):

To enhance the efficiency of radiotherapy (RT), implementation of individual-based treatment is essential. In this way, determining individual intrinsic radiosensitivity (IRS) can be useful to achieve minimal adverse effects of RT. The present study aimed to identify IRS of breast cancer (BC) patients through determination of radiation-induced DNA double-strand breaks (DSBs), repair kinetics, and acute normal tissue complications induced by RT.

Materials and Methods:

DSBs induction and its repair kinetics in 50 BC patients’ lymphocytes were analyzed by flow cytometric analysis of H2AX Ser-139 phosphorylation at 30 min, 3 and 24 hr after in vitro irradiation. In vivo skin dosimetry was done by GAFChromic films and acute skin toxicity was scored by radiation oncologists according to the criteria of Radiation Therapy and Oncology Group (RTOG) in all patients with similar prescribed treatment.

Results:

The average surface dose for patients ranged from 0.92 to 1.9 Gy and correlation analysis showed no significant relationship with weekly acute skin reactions. Formation of γH2AX after 30 min, slope of dose-response curve and repair kinetics of DSBs after 3 and 24 hr (intrinsic radiosensitivity) were significantly correlated with the RTOG scores following irradiation (clinical radiosensitivity) (r=0.48 and P-value<0.0001, r=0.72 and P-value<0.0001, r=0.48 and P-value<0.001, and finally r=0.53 and P-value<0.001, respectively; (using Pearson’s correlation test).

Conclusion:

Flow cytometric analysis of DNA DSBs by γH2AX measurement has the potential to be developed into a clinical predictor for identifying the overreactor patients prior to RT. Our result suggests that the slope-related quantity based on the linear pattern of the dose-response curve has the merit to predict overreactor patients with a sensitivity of 89% and a specificity of 94%.

TGF-β-induced CCR8 promoted macrophage transdifferentiation into myofibroblast-like cells

Background: Idiopathic pulmonary fibrosis (IPF) is an interstitial disease of unknown origin, characterized by tissue fibrosis, for which currently there is no effective treatment. Macrophages, the main immune cells in lung tissue, are involved in the whole process of pulmonary fibrosis. In recent years, intercellular transformation has led to wide spread concern among pulmonary fibrosis researchers. Macrophages with flexible heterogeneity and plasticity participate in different physiological processes in the body. Cell chemokine receptor 8 (CCR8) is expressed in a variety of cells and plays a significant chemotactic role in the induction of cell activation and migration. It can also promote the differentiation of macrophages under certain environmental conditions. The current study is intended to explore the role of CCR8 in macrophage to myofibroblast transdifferentiation (MMT) in IPF. Methods: We conducted experiments using CCR8-specific small interfering RNA (siRNA), an autophagy inhibitor (3-methyladenine, 3-MA), and an agonist (rapamycin) to explore the underlying mechanisms of macrophage transdifferentiation into myofibroblast cells in transforming growth factor-beta (TGF-β)-induced pulmonary fibrosis. Results: TGF-β treatment increased the CCR8 protein level in a time- and dose-dependent manner in mouse alveolar macrophages, as well as macrophage transdifferentiation-related markers, including vimentin, collagen 1, and a-SMA, and cell migration. In addition, the levels of autophagy were enhanced in macrophages treated with TGF-β. We found that 3-MA, an autophagy inhibitor, decreased the expression levels of macrophage transdifferentiation-related markers and attenuated cell migration. Furthermore, the inhibition of CCR8 via CCR8-specific siRNA reduced the levels of autophagy and macrophage transdifferentiation-related markers, and inhibited the cell migration. Enhancing autophagy with rapamycin attenuated the inhibition effect of CCR8-specific siRNA on macrophage migration and the increase in myofibroblast marker proteins. Conclusions: Our findings showed that the macrophages exposed to TGF-β had the potential to transdifferentiate into myofibroblasts and CCR8 was involved in the process. The effect of CCR8 on TGF-β-induced macrophage transdifferentiation occurs mainly through autophagy. Targeting CCR8 may be a novel therapeutic strategy for the treatment of IPF.

C8Mab-3: An Anti-Mouse CCR8 Monoclonal Antibody for Immunocytochemistry

The C-C motif chemokine receptor 8 (CCR8) is highly expressed in regulatory T cells. CCR8 is also expressed in many cancers and is associated with those progression. The development of monoclonal antibodies (mAbs) for CCR8 leads to cancer immunotherapy and elucidation of unknown mechanisms of CCR8-dependent cancer progression. In this study, we have developed an anti-mouse CCR8 (mCCR8) mAb (clone C₈Mab-3, rat IgG₁, kappa) using the Cell-Based Immunization and Screening (CBIS) method. We revealed that C₈Mab-3 and its recombinant antibody (recC₈Mab-3) bind to mCCR8-overexpressed Chinese hamster ovary (CHO)-K1 cells (CHO/mCCR8), but not to the parental CHO-K1 cells, in flow cytometry. In addition, C₈Mab-3 and recC₈Mab-3 reacted to P388 (a mouse lymphocyte-like cell) and J774-1 (a mouse macrophage-like cell), which express endogenous mCCR8. C₈Mab-3 also detected exogenous and endogenous mCCR8 using immunocytochemistry. These results suggest that C₈Mab-3, developed using the CBIS method, is useful for immunocytochemistry against exogenous and endogenous mCCR8.

T cell-attracting CCL18 chemokine is a dominant rejection signal during limb transplantation

Limb transplantation is a life-changing procedure for amputees. However, limb recipients have a 6-fold greater rejection rate than solid organ transplant recipients, related in part to greater immunogenicity of the skin. Here, we report a detailed immunological and molecular characterization of individuals who underwent bilateral limb transplantation at our institution. Circulating Th17 cells are increased in limb transplant recipients over time. Molecular characterization of 770 genes in skin biopsies reveals upregulation of T cell effector immune molecules and chemokines, particularly CCL18. Skin antigen-presenting cells primarily express the chemokine CCL18, which binds to the CCR8 receptor. CCL18 treatment recruits more allo-T cells to the skin xenograft in a humanized skin transplantation model, leading to signs of accelerated graft rejection. Blockade of CCR8 remarkedly decreases CCL18-induced allo-T cell infiltration. Our results suggest that targeting the CCL18:CCR8 pathway could be a promising immunosuppressive approach in transplantation.

CCR8-targeted specific depletion of clonally expanded Treg cells in tumor tissues evokes potent tumor immunity with long-lasting memory

Immunosuppressive Foxp3-expressing regulatory T cells (Tregs) in tumor tissues are assumed to be clonally expanding via recognizing tumor-associated antigens. By single-cell RNA sequencing, we have searched for the molecules that are specifically expressed by such multiclonal tumor Tregs, but not by tumor-infiltrating effector T cells or natural Tregs in other tissues. The search revealed the chemokine receptor CCR8 as a candidate. Treatment of tumor-bearing mice with cell-depleting anti-CCR8 antibody indeed selectively removed multiclonal tumor Tregs without affecting effector T cells or tissue Tregs, eradicating established tumors with induction of potent tumor-specific effector/memory T cells and without activating autoimmune T cells. Thus, specific depletion of clonally expanding tumor Tregs is clinically instrumental for evoking effective tumor immunity without autoimmune adverse effects.

Foxp3-expressing CD25⁺CD4⁺ regulatory T cells (Tregs) are abundant in tumor tissues. Here, hypothesizing that tumor Tregs would clonally expand after they are activated by tumor-associated antigens to suppress antitumor immune responses, we performed single-cell analysis on tumor Tregs to characterize them by T cell receptor clonotype and gene-expression profiles. We found that multiclonal Tregs present in tumor tissues predominantly expressed the chemokine receptor CCR8. In mice and humans, CCR8⁺ Tregs constituted 30 to 80% of tumor Tregs in various cancers and less than 10% of Tregs in other tissues, whereas most tumor-infiltrating conventional T cells (Tconvs) were CCR8^–. CCR8⁺ tumor Tregs were highly differentiated and functionally stable. Administration of cell-depleting anti-CCR8 monoclonal antibodies (mAbs) indeed selectively eliminated multiclonal tumor Tregs, leading to cure of established tumors in mice. The treatment resulted in the expansion of CD8⁺ effector Tconvs, including tumor antigen-specific ones, that were more activated and less exhausted than those induced by PD-1 immune checkpoint blockade. Anti-CCR8 mAb treatment also evoked strong secondary immune responses against the same tumor cell line inoculated several months after tumor eradication, indicating that elimination of tumor-reactive multiclonal Tregs was sufficient to induce memory-type tumor-specific effector Tconvs. Despite induction of such potent tumor immunity, anti-CCR8 mAb treatment elicited minimal autoimmunity in mice, contrasting with systemic Treg depletion, which eradicated tumors but induced severe autoimmune disease. Thus, specific removal of clonally expanding Tregs in tumor tissues for a limited period by cell-depleting anti-CCR8 mAb treatment can generate potent tumor immunity with long-lasting memory and without deleterious autoimmunity.

Chemokine Receptor-Targeted Therapies: Special Case for CCR8

Immune checkpoint blockade inhibitors (CBIs) targeting cytotoxic T lymphocyte associated protein-4 (CTLA-4) and program death receptor-1 (PD-1) or its ligand-1 (PD-L1) have transformed the outlook of many patients with cancer. This remarkable progress has highlighted, from the translational point of view, the importance of immune cells in the control of tumor progression. There is still room for improvement, since current CBI therapies benefit a minority of patients. Moreover, interference with immune checkpoint receptors frequently causes immune related adverse events (irAEs) with life-threatening consequences in some of the patients. Immunosuppressive cells in the tumor microenvironment (TME), including intratumoral regulatory T (Treg) cells, tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), contribute to tumor progression and correlate with a negative disease outlook. Recent reports revealed the selective expression of the chemokine receptor CCR8 on tumor Treg cells, making CCR8 a promising target in translational research. In this review, I summarize our current knowledge about the cellular distribution and function of CCR8 in physiological and pathophysiological processes. The discussion includes an assessment of how the removal of CCR8-expressing cells might affect both anti-tumor immunity as well as immune homeostasis at remote sites. Based on these considerations, CCR8 appears to be a promising novel target to be considered in future translational research.

Chemokine CCL18 Promotes Phagocytosis Through Its Receptor CCR8 Rather than PITPNM3 in Human Microglial Cells

CCL18 is a CC chemokine that exhibits diverse functions through interaction with various cell subsets with both proinflammatory anti-inflammatory properties through its receptors CCR8 (CC chemokine receptor 8) and PITPNM3 (phosphatidylinositol transfer protein 3). However, the function of CCL18 in microglia remains unclear. In this study, we show that CCL18 did not change the expression of the inflammatory factors, interleukin (IL)-1β, IL-6, tumor necrosis factor alpha (TNF-α), or inducible nitric oxide synthase (iNOS), but significantly induced expression of the macrophage markers, MRC-1 and ARG-1 M2, in a human microglial clone 3 cell line (HMC3). Phagocytosis by HMC3 cells was significantly enhanced in the presence of CCL18, indicated by uptake of amyloid-β and dextran. CCR8 and PITPNM3 were both expressed on HMC3 cells, but selective knockdown of CCR8 and PITPNM3 showed that only the former played a dominant role in phagocytosis of HMC3 through the nuclear factor kappa B (NF-κB)/Src signaling pathway. Our results suggest that CCL18 could have anti-inflammatory activity and activate the phagocytic function of microglia, which is involved in neural development, homeostasis, and repair mechanisms.

Chemokines in the Landscape of Cancer Immunotherapy: How They and Their Receptors Can Be Used to Turn Cold Tumors into Hot Ones?

Over the last decade, monoclonal antibodies to immune checkpoint inhibitors (ICI), also known as immune checkpoint blockers (ICB), have been the most successful approach for cancer therapy. Starting with mAb to cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors in metastatic melanoma and continuing with blockers of the interactions between program cell death 1 (PD-1) and its ligand program cell death ligand 1 (PDL-1) or program cell death ligand 2 (PDL-2), that have been approved for about 20 different indications. Yet for many cancers, ICI shows limited success. Several lines of evidence imply that the limited success in cancer immunotherapy is associated with attempts to treat patients with "cold tumors" that either lack effector T cells, or in which these cells are markedly suppressed by regulatory T cells (Tregs). Chemokines are a well-defined group of proteins that were so named due to their chemotactic properties. The current review focuses on key chemokines that not only attract leukocytes but also shape their biological properties. CXCR3 is a chemokine receptor with 3 ligands. We suggest using Ig-based fusion proteins of two of them: CXL9 and CXCL10, to enhance anti-tumor immunity and perhaps transform cold tumors into hot tumors. Potential differences between CXCL9 and CXCL10 regarding ICI are discussed. We also discuss the possibility of targeting the function or deleting a key subset of Tregs that are CCR8+ by monoclonal antibodies to CCR8. These cells are preferentially abundant in several tumors and are likely to be the key drivers in suppressing anti-cancer immune reactivity.

Splenectomy increases blood pressure and abolishes sex differences in renal T-regulatory cells in spontaneously hypertensive rats

Over the past decade there has been increasing support for a role of the immune system in the development of hypertension. Our lab has previously reported that female spontaneously hypertensive rats (SHRs) have a blood pressure (BP)-dependent increase in anti-inflammatory renal regulatory T cells (Tregs), corresponding to lower BP compared with males. However, little is known regarding the mechanism for greater renal Tregs in females. The current study was designed to test the hypothesis that the greater relative abundance of renal Tregs in female SHR is due to greater Treg production. To test this hypothesis, T cell profiles were measured in the spleen by flow cytometry in male and female SHR at 5 and 14 weeks of age. Splenic Tregs did not differ between males and females, suggesting sex differences in renal Tregs is not due to differences in production. To assess the role of the spleen in sex differences in renal Tregs and BP control, rats were randomized to receive sham surgery (CON) or splenectomy (SPLNX) at 12 weeks of age and implanted with telemeters to measure BP. After 2 weeks, kidneys were harvested for flow cytometric analysis of T cells. Splenectomy increased BP in both sexes after 2 weeks. Renal Tregs decreased in both sexes after splenectomy, abolishing the sex differences in renal Tregs. In conclusion, splenic Tregs were comparable in male and female SHRs, suggesting that sex differences in renal Tregs is due to differences in renal Treg recruitment, not Treg production.

CCR8 marks highly suppressive Treg cells within tumours but is dispensable for their accumulation and suppressive function

CD4⁺ regulatory T (Treg) cells, dependent upon the transcription factor Foxp3, contribute to tumour immunosuppression but are also required for immune homeostasis. There is interest in developing therapies that selectively target the immunosuppressive function of Treg cells within tumours without disrupting their systemic anti-inflammatory function. High levels of expression of chemokine (C-C motif) receptor 8 (CCR8) discriminate Treg cells within tumours from those found in systemic lymphoid tissues. It has recently been proposed that disruption of CCR8 function using blocking anti-CCR8 antibodies results in reduced accumulation of Treg cells within tumours and disruption of their immunosuppressive function. Here, using Ccr8^-/- mice, we show that CCR8 function is not required for Treg cell accumulation or immunosuppression in the context of syngeneic MC38 colorectal adenocarcinoma and B16 melanoma tumours. We observed high levels of CCR8 expression on tumour-infiltrating Treg cells which were abolished in Ccr8^-/- mice. High levels of CCR8 marked cells with high levels of suppressive function. However, whereas systemic ablation of Treg cells resulted in strikingly diminished tumour burden, growth of subcutaneously implanted tumours was unaffected by systemic CCR8 loss. Consistently, we observed minimal impact of systemic CCR8 ablation on the frequency, phenotype and function of tumour-infiltrating Treg cells and conventional T (Tconv) function. These findings suggest that CCR8 is not required for Treg cell accumulation and immunosuppressive function within tumours and that depletion of CCR8⁺ Treg cells rather than blockade of CCR8 function is a more promising avenue for selective immunotherapy.

Immunomodulation of T Helper Cells by Tumor Microenvironment in Oral Cancer Is Associated With CCR8 Expression and Rapid Membrane Vitamin D Signaling Pathway

The immune system plays a key role in the protective response against oral cancer; however, the tumor microenvironment (TME) impairs this anti-cancer response by modulating T helper (Th) responses and promoting an anti-inflammatory environment. Regulatory T cells (Tregs) and Th2 effector cells (Teff) are associated with poor prognosis in oral squamous cell carcinoma (OSCC). However, the main immunomodulatory mechanisms associated with the enrichment of these subsets in OSCC remain unknown. We characterized Th-like lineages in Tregs and Teff and evaluated immunomodulatory changes induced by the TME in OSCC. Our phenotypic data revealed a higher distribution of tumour-infiltrating CCR8⁺ and Th2-like Treg in OSCC compared with non-malignant samples, whereas the percentages of Th1 cells were reduced in cancer. We then analyzed the direct effect of the TME by exposing T cell subsets to cancer secretomes and observed the OSCC secretome induced CCR8 expression and reduced cytokine production from both subsets. Transcriptomic analysis showed that the co-culture with OSCC secretome induced several gene changes associated with the vitamin D (VitD) signaling pathway in T cells. In addition, proteomic analysis identified the presence of several proteins associated with prostaglandin E2 (PGE2) production by rapid membrane VitD signaling and a reduced presence of the VitD binding protein. Thus, we analyzed the effect of VitD and PGE2 and observed that VitD promotes a regulatory Th2-like response with CCR8 expression whilst PGE2 also modulated CCR8 but inhibited cytokine production in combination with VitD. Finally, we evaluated the presence of CCR8 ligand in OSCC and observed increased chemokine CCL18, which was also able to upregulate CCR8 in activated Th cells. Overall, our data showed the immunomodulatory changes induced by the TME involving CCR8 expression and regulatory Th2 phenotypes, which are associated with PGE2 mediated VitD signaling pathway and CCL18 expression in OSCC.

Development of Anti-Mouse CC Chemokine Receptor 8 Monoclonal Antibodies for Flow Cytometry

CC chemokine receptor 8 (CCR8) belongs to the class A of G protein-coupled receptor. It is highly expressed on Treg and T helper 2 (T_H2) cells recruited to the inflammation site and is implicated in allergy and asthma. Recently, CCR8+Treg cells have been suggested to be a master regulator in the immunosuppressive tumor microenvironment; therefore, developing sensitive monoclonal antibodies (mAbs) for CCR8 has been desired. This study established a specific and sensitive mAb for mouse CCR8 (mCCR8), which is useful for flow cytometry by using the Cell-Based Immunization and Screening (CBIS) method. The established anti-mCCR8 mAb, C₈Mab-2 (rat IgG_2b, kappa), reacted with mCCR8-overexpressed Chinese hamster ovary-K1 (CHO/mCCR8) cells and P388 (mouse lymphoid neoplasma) or J774-1 (mouse macrophage-like) cells, which express endogenous mCCR8 by flow cytometry. C₈Mab-2, which was established by the CBIS method, could be useful for elucidating the mCCR8-related biological response by flow cytometry.

CCR8 Signaling via CCL1 Regulates Responses of Intestinal IFN-γ Producing Innate Lymphoid CelIs and Protects From Experimental Colitis

A diverse spectrum of immune cells populates the intestinal mucosa reflecting the continuous stimulation by luminal antigens. In lesions of patients with inflammatory bowel disease, an aberrant inflammatory process is characterized by a very prominent infiltrate of activated immune cells producing cytokines and chemokines. These mediators perpetuate intestinal inflammation or may contribute to mucosal protection depending on the cellular context. In order to further characterize this complex immune cell network in intestinal inflammation, we investigated the contribution of the chemokine receptor CCR8 to development of colitis using a mouse model of experimental inflammation. We found that CCR8^-/- mice compared to wildtype controls developed strong weight loss accompanied by increased histological and endoscopic signs of mucosal damage. Further experiments revealed that this gut protective function of CCR8 seems to be selectively mediated by the chemotactic ligand CCL1, which was particularly produced by intestinal macrophages during colitis. Moreover, we newly identified CCR8 expression on a subgroup of intestinal innate lymphoid cells producing IFN-γ and linked a functional CCL1/CCR8 axis with their abundance in the gut. Our data therefore suggest that this pathway supports tissue-specific ILC functions important for intestinal homeostasis. Modulation of this regulatory circuit may represent a new strategy to treat inflammatory bowel disease in humans.

Palladium-catalyzed cross-coupling reactions on a bromo-naphthalene scaffold in the search for novel human CC chemokine receptor 8 (CCR8) antagonists

The naphthalene sulfonamide scaffold is known to possess CCR8 antagonistic properties. In order to expand the structure-activity relationship study of this compound class, a variety of palladium-catalyzed cross-coupling reactions was performed on a bromo-naphthalene precursor yielding a diverse library. These compounds displayed CCR8 antagonistic properties in binding and calcium mobilization assays, with IC₅₀ values in the 0.2 - 10 µM range. The decreased activity, when compared to the original lead compound, was rationalized by homology molecular modeling.

Disruption of the CCL1-CCR8 axis inhibits vascular Treg recruitment and function and promotes atherosclerosis in mice

The CC chemokine 1 (CCL1, also called I-309 or TCA3) is a potent chemoattractant for leukocytes that plays an important role in inflammatory processes and diseases through binding to its receptor CCR8. Here, we investigated the role of the CCL1-CCR8 axis in atherosclerosis. We found increased expression of CCL1 in the aortas of atherosclerosis-prone fat-fed apolipoprotein E (Apoe)-null mice; moreover, in vitro flow chamber assays and in vivo intravital microscopy demonstrated an essential role for CCL1 in leukocyte recruitment. Mice doubly deficient for CCL1 and Apoe exhibited enhanced atherosclerosis in aorta, which was associated with reduced plasma levels of the anti-inflammatory interleukin 10, an increased splenocyte Th1/Th2 ratio, and a reduced regulatory T cell (Treg) content in aorta and spleen. Reduced Treg recruitment and aggravated atherosclerosis were also detected in the aortas of fat-fed low-density lipoprotein receptor-null mice treated with CCR8 blocking antibodies. These findings demonstrate that disruption of the CCL1-CCR8 axis promotes atherosclerosis by inhibiting interleukin 10 production and Treg recruitment and function.

The Chemokine Receptor CCR8 Promotes the Migration of Dendritic Cells into the Lymph Node Parenchyma to Initiate the Allergic Immune Response

The migration of mature dendritic cells (DCs) into the draining lymph node (dLN) is thought to depend solely on the chemokine receptor CCR7. CD301b+ DCs migrate into the dLN after cutaneous allergen exposure and are required for T helper 2 (Th2) differentiation. We found that CD301b+ DCs poorly upregulated CCR7 expression after allergen exposure and required a second chemokine signal, mediated by CCR8 on CD301b+ DCs and its ligand CCL8, to exit the subcapsular sinus (SCS) and enter the lymph node (LN) parenchyma. After allergen exposure, CD169+SIGN-R1+ macrophages in interfollicular regions produced CCL8, which synergized with CCL21 in a Src-kinase-dependent manner to promote CD301b+ DC migration. In CCR8-deficient mice, CD301b+ DCs remained in the SCS and were unable to enter the LN parenchyma, resulting in defective Th2 differentiation. We have defined a CCR8-dependent stepwise mechanism of DC-subset-specific migration through which LN CD169+SIGN-R1+ macrophages control the polarization of the adaptive immune response.

Glycosylated extracellular vesicles released by glioblastoma cells are decorated by CCL18 allowing for cellular uptake via chemokine receptor CCR8

Cancer cells release extracellular vesicles (EVs) that contain functional biomolecules such as RNA and proteins. EVs are transferred to recipient cancer cells and can promote tumour progression and therapy resistance. Through RNAi screening, we identified a novel EV uptake mechanism involving a triple interaction between the chemokine receptor CCR8 on the cells, glycans exposed on EVs and the soluble ligand CCL18. This ligand acts as bridging molecule, connecting EVs to cancer cells. We show that glioblastoma EVs promote cell proliferation and resistance to the alkylating agent temozolomide (TMZ). Using in vitro and in vivo stem-like glioblastoma models, we demonstrate that EV-induced phenotypes are neutralised by a small molecule CCR8 inhibitor, R243. Interference with chemokine receptors may offer therapeutic opportunities against EV-mediated cross-talk in glioblastoma.

Role of Conserved Disulfide Bridges and Aromatic Residues in Extracellular Loop 2 of Chemokine Receptor CCR8 for Chemokine and Small Molecule Binding

Chemokine receptors play important roles in the immune system and are linked to several human diseases. The initial contact of chemokines with their receptors depends on highly specified extracellular receptor features. Here we investigate the importance of conserved extracellular disulfide bridges and aromatic residues in extracellular loop 2 (ECL-2) for ligand binding and activation in the chemokine receptor CCR8. We used inositol 1,4,5-trisphosphate accumulation and radioligand binding experiments to determine the impact of receptor mutagenesis on both chemokine and small molecule agonist and antagonist binding and action in CCR8. We find that the seven-transmembrane (TM) receptor conserved disulfide bridge (7TM bridge) linking transmembrane helix III (TMIII) and ECL-2 is crucial for chemokine and small molecule action, whereas the chemokine receptor conserved disulfide bridge between the N terminus and TMVII is needed only for chemokines. Furthermore, we find that two distinct aromatic residues in ECL-2, Tyr(184) (Cys + 1) and Tyr(187) (Cys + 4), are crucial for binding of the CC chemokines CCL1 (agonist) and MC148 (antagonist), respectively, but not for small molecule binding. Finally, using in silico modeling, we predict an aromatic cluster of interaction partners for Tyr(187) in TMIV (Phe(171)) and TMV (Trp(194)). We show in vitro that these residues are crucial for the binding and action of MC148, thus supporting their participation in an aromatic cluster with Tyr(187) This aromatic cluster appears to be present in a large number of CC chemokine receptors and thereby could play a more general role to be exploited in future drug development targeting these receptors.

CC Chemokine Ligand 18 in ANCA-Associated Crescentic GN

ANCA-associated vasculitis is the most frequent cause of crescentic GN. To define new molecular and/or cellular biomarkers of this disease in the kidney, we performed microarray analyses of renal biopsy samples from patients with ANCA-associated crescentic GN. Expression profiles were correlated with clinical data in a prospective study of patients with renal ANCA disease. CC chemokine ligand 18 (CCL18), acting through CC chemokine receptor 8 (CCR8) on mononuclear cells, was identified as the most upregulated chemotactic cytokine in patients with newly diagnosed ANCA-associated crescentic GN. Macrophages and myeloid dendritic cells in the kidney were detected as CCL18-producing cells. The density of CCL18(+) cells correlated with crescent formation, interstitial inflammation, and impairment of renal function. CCL18 protein levels were higher in sera of patients with renal ANCA disease compared with those in sera of patients with other forms of crescentic GN. CCL18 serum levels were higher in patients who suffered from ANCA-associated renal relapses compared with those in patients who remained in remission. Using a murine model of crescentic GN, we explored the effects of the CCL18 murine functional analog CCL8 and its receptor CCR8 on kidney function and morphology. Compared with wild-type mice, Ccr8(-/-) mice had significantly less infiltration of pathogenic mononuclear phagocytes. Furthermore, Ccr8(-/-) mice maintained renal function better and had reduced renal tissue injury. In summary, our data indicate that CCL18 drives renal inflammation through CCR8-expressing cells and could serve as a biomarker for disease activity and renal relapse in ANCA-associated crescentic GN.

In silico characterization of binding mode of CCR8 inhibitor: homology modeling, docking and membrane based MD simulation study

Human CC-chemokine receptor 8 (CCR8) is a crucial drug target in asthma that belongs to G-protein-coupled receptor superfamily, which is characterized by seven transmembrane helices. To date, there is no X-ray crystal structure available for CCR8; this hampers active research on the target. Molecular basis of interaction mechanism of antagonist with CCR8 remains unclear. In order to provide binding site information and stable binding mode, we performed modeling, docking and molecular dynamics (MD) simulation of CCR8. Docking study of biaryl-ether-piperidine derivative (13C) was performed inside predefined CCR8 binding site to get the representative conformation of 13C. Further, MD simulations of receptor and complex (13C-CCR8) inside dipalmitoylphosphatidylcholine lipid bilayers were performed to explore the effect of lipids. Results analyses showed that the Gln91, Tyr94, Cys106, Val109, Tyr113, Cys183, Tyr184, Ser185, Lys195, Thr198, Asn199, Met202, Phe254, and Glu286 were conserved in both docking and MD simulations. This indicated possible role of these residues in CCR8 antagonism. However, experimental mutational studies on these identified residues could be effective to confirm their importance in CCR8 antagonism. Furthermore, calculated Coulombic interactions represented the crucial roles of Glu286, Lys195, and Tyr113 in CCR8 antagonism. Important residues identified in this study overlap with the previous non-peptide agonist (LMD-009) binding site. Though, the non-peptide agonist and currently studied inhibitor (13C) share common substructure, but they differ in their effects on CCR8. So, to get more insight into their agonist and antagonist effects, further side-by-side experimental studies on both agonist (LMD-009) and antagonist (13C) are suggested.

Role of lymphatic vasculature in regional and distant metastases

In cancer, lymphatic vasculature has been traditionally viewed only as a transportation system for metastatic cells. It has now become clear that lymphatics perform many additional functions which could influence cancer progression. Lymphangiogenesis, induced at the primary tumor site and at distant sites, potently augments metastasis. Lymphatic endothelial cells (LECs) control tumor cell entry and exit from the lymphatic vessels. LECs also control immune cell traffic and directly modulate adaptive immune responses. This review highlights advances in our understanding of the mechanisms by which lymphatic vessels, and in particular lymphatic endothelium, impact metastasis.