CC Chemokine Receptor 4 Antagonist Research Articles

Development of a Sensitive Anti-Mouse CCR5 Monoclonal Antibody for Flow Cytometry.

C-C chemokine receptor 5 (CCR5), a member of the G protein-coupled receptor family, is the most common coreceptor for the human immunodeficiency virus type 1. CCR5 is also involved in the pathogenesis of tumors and inflammatory diseases. The CCR5 antagonists including monoclonal antibodies (mAbs) have been developed and evaluated in clinical trials. In this study, we developed novel mAbs for mouse CCR5 (mCCR5) using the Cell-Based Immunization and Screening (CBIS) method. One of the established anti-mCCR5 mAbs, C5Mab-2 (rat IgG2b, kappa), reacted with mCCR5-overexpressed Chinese hamster ovary-K1 (CHO/mCCR5) and an endogenously mCCR5-expressing cell line (L1210) by flow cytometry. Using flow cytometry, the dissociation constant (KD) of C5Mab-2 for CHO/mCCR5 was determined as 4.3 × 10-8 M. These results indicated that C5Mab-2 is useful for the detection of mCCR5 in flow cytometry and may be applicable to obtain the proof of concept in preclinical studies.

Blockade of CCR5 and CXCR3 attenuates murine acute graft-versus-host disease through modulating donor-derived T-cell distribution and function.

Lymphocyte trafficking via chemokine receptors such as C-C chemokine receptor 5 (CCR5) and CXCR3 plays a critical role in the pathogenesis of acute graft-versus-host disease (aGVHD). Our previous studies showed that the addition of CCR5 or CXCR3 antagonists could only slightly alleviate the development of aGVHD. Given the specificity of T lymphocytes bearing CXCR3 and CCR5, we investigated whether combined CCR5 and CXCR3 blockade could further attenuate murine aGVHD. A mouse model of aGVHD was established to assess the efficacy of CCR5 and/or CXCR3 blockade on the development of aGVHD. The distribution of lymphocytes was calculated by quantification of immunostaining cells. The immunomodulatory effect on T cells was assessed by evaluating T-cell proliferation, viability, and differentiation. Using the murine allogeneic hematopoietic stem cell transplantation model, we demonstrated that blockade of both CCR5 and CXCR3 could efficiently alleviate the development of aGVHD. Further investigation on the immune mechanisms for this prophylactic effect showed that more T cells were detained into secondary lymphoid organs (SLOs), which may lead to reduced infiltration of T cells into GVHD target organs. Our study also showed that T cells detained in SLOs dampened the activation, suppressed the polarization toward T helper type 1 (Th1) and T cytotoxic type 1 (Tc1) cells, and induced the production of Treg cells. These data suggest that concurrent blockade of CCR5 and CXCR3 attenuates murine aGVHD through modulating donor-derived T-cell distribution and function, and this might be applicable for aGVHD prophylaxis in clinical settings.

CCR5 regulates Aβ1-42-induced learning and memory deficits in mice

C–C chemokine receptor 5 (CCR5) is a chemokine receptor involved in immune responses and a co-receptor for HIV infection. Recently, CCR5 has also been reported to play a role in synaptic plasticity, learning and memory, and cognitive deficits associated with normal aging, traumatic brain injury (TBI), and HIV-associated neurocognitive disorder (HAND). In contrast, the role of CCR5 in cognitive deficits associated with other disorders, including Alzheimer’s disease (AD), is much less understood. Studies have reported an increase in expression of CCR5 or its ligands in both AD patients and AD rodent models, suggesting a correlation between AD and CCR5 expression. However, whether blocking CCR5 in specific brain regions, such as the hippocampus, could improve memory deficits in AD mouse models is unknown. To study the potential causal role of CCR5 in cognitive deficits in AD, we injected soluble Aβ1-42 or a control (Aβ42-1) oligomers in the dorsal CA1 region of the hippocampus and found that Aβ1-42 injection resulted in severe memory impairment in the object place recognition (OPR) and novel object recognition (NOR) tests. Aβ1-42 injection caused an increase in Ccr5, Ccl3, and Ccl4 in the dorsal hippocampus, and the expression levels of CCR5 and its ligands remained elevated at 2 weeks after Aβ1-42 injection. Knocking down Ccr5 in the CA1 region of dorsal hippocampus reversed the increase in microglia number and size in dorsal CA1 and rescued memory deficits. These results indicate that CCR5 plays an important role in modulating Aβ1-42-induced learning and memory deficits, and suggest that CCR5 antagonists may serve as a potential treatment to improve cognitive deficits associated with AD.

C-C chemokine receptor 4 (CCR4)-positive regulatory T cells interact with tumor-associated macrophages to facilitate metastatic potential after radiation

PurposeOur previous study revealed that elevated C-C motif chemokine ligand 2 (CCL2) secretion by irradiated cancer cells recruited C-C motif chemokine receptor 2 (CCR2)-positive myeloid cells and polarized M2-type tumor-associated macrophages (TAMs), promoting lung metastasis in an established mouse model. This study investigated the impact of CCL2 and TAMs on adaptive immunity. MethodsWe assessed the influence of CCL2 and TAMs on adaptive immunity through two ectopic allograft mouse models constructed with MB49 bladder cancer cells and Lewis lung carcinoma cells. Both models exhibited delayed primary tumor growth following radiation therapy (RT), but RT promoted the development of pulmonary metastases in C57BL/6 mice. Additionally, we employed a direct coculture system to investigate the interaction between macrophages and target cells in the context of adaptive immunity. ResultsC-C motif chemokine receptor 4 (CCR4)-positive regulatory T cells (Tregs) were recruited to the postirradiated tumor microenvironment (TME). Utilizing a CCR4 antagonist to inhibit CCL2-CCR4 activation reversed the infiltration of CCR4 + Tregs and reduced the incidence of pulmonary metastases. In addition, a positive feedback loop between M2-type TAMs and Tregs was observed. The combined blockade of the CCL2-CCR4 and CCL2-CCR2 signaling pathways further decreased the risk of RT-promoted lung metastasis. ConclusionThe recruitment of CCR4 + Tregs to the postirradiated TME increases the metastatic potential of tumor cells through increased interactions with M2-type TAMs. A significant reduction in post-RT lung metastases in ectopic mouse models was achieved by disrupting the recruitment of both CCR4 + Tregs and CCR2 + myeloid cells, which are TAM precursors.

Role of periostin in inflammatory bowel disease development and synergistic effects mediated by the CCL5-CCR5 axis.

Inflammatory bowel disease (IBD), comprising mainly Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disease of the gastrointestinal tract. In recent years, a wealth of data has been accumulated demonstrating the complex interplay of many different factors in the pathogenesis of IBD. Among these are factors impacting the epithelial barrier function, including vessel and extracellular matrix (ECM) formation, the gut microbiome (e.g., bacterial antigens), and, most importantly, the production of cytokines (pro- and anti-inflammatory) directly shaping the immune response. Patients failing to resolve the acute intestinal inflammation develop chronic inflammation. It has been shown that the expression of the matricellular protein periostin is enhanced during IBD and is one of the drivers of this disease. The C-C chemokine receptor 5 (CCR5) is engaged by the chemotactic mediators CCL3/MIP-1α, CCL4/MIP-1β, and CCL5/RANTES. CCR5 blockade has been reported to ameliorate inflammation in a murine IBD model. Thus, both periostin and CCR5 are involved in the development of IBD. In this study, we investigated the potential crosstalk between the two signaling systems and tested a highly potent CCL5 derivative acting as a CCR5 antagonist in a murine model of IBD. We observed that the absence of periostin influences the CCR5-expressing cell population of the gut. Our data further support the notion that targeted modulation of the periostin and CCR5 signaling systems bears therapeutic potential for IBD.

Synthesis of a novel CCR1 antagonist for treatment of glioblastoma

Glioblastoma is a brain cancer caused by the presence of a fast-growing, malignant tumor in the brain. As of now, this cancer is universally lethal due to lack of efficacious treatment options. C-C chemokine receptor 1 (CCR1) is a G-protein coupled receptor that controls chemotaxis, the movement of cells in response to chemical stimuli. Inhibiting these receptors could retard the growth of the malignant tumor by inhibiting chemotaxis. This research aims to synthesize potential CCR1 antagonists by coupling carboxylic acids with a triazole core. We synthesized these compounds using a simple carboxylic acid coupling and confirmed the identity of the final compounds using nuclear magnetic resonance (NMR) spectroscopy. Further testing of these compounds in inhibition bioassays is planned to be done when lab space becomes accessible again.

Pharmacological inhibition of C-C chemokine receptor 4 aggravates atherosclerosis through prevention of regulatory T cell recruitment to the lesions

Abstract Background Regulatory T cells (Tregs) are demonstrated to play a protective role in the development of atherosclerosis. However, their sites of action in atherosclerosis remain unclear. Although C-C chemokine receptor 4 (CCR4) has been shown to contribute to the accumulation of Tregs in inflamed tissues and prevention of experimental autoimmune diseases, the role of CCR4 in Treg migration to atherosclerotic lesions and suppression of plaque formation remains unknown. Methods and results We intraperitoneally injected 8-week-old apolipoprotein E–deficient mice fed a normal diet with vehicle (n=9) or a 4-μg dose of a CCR4 antagonist (n=10) 3 times weekly for 8 weeks and evaluated atherosclerotic lesions at 16 weeks old. Administration of the CCR4 antagonist significantly aggravated atherosclerotic plaque formation (aortic sinus plaque area: 2.91±0.87×104 μm2 versus 5.41±0.98×104 μm2 in control vehicle-treated and CCR4 antagonist-treated mice, respectively; P<0.05), associated with increased accumulation of macrophages and CD4+T cells in the plaques. Flow cytometric analysis revealed a decrease in Foxp3+ Tregs in the para-aortic lymph nodes and thoracoabdominal aortas of CCR4 antagonist-treated mice, along with a tendency toward increase in CD44highCD62Lloweffector T cells in para-aortic lymph nodes, indicating CCR4-dependent migration of Tregs to atherosclerotic lesions and their possible atheroprotective role. We observed no changes in splenic Foxp3+ Tregs and effector T cells following CCR4 antagonist treatment. We also investigated the effect of CCR4 blockade on advanced atherosclerosis using LDL receptor–deficient mice fed a high-cholesterol diet. Although 8-week treatment with the CCR4 antagonist led to a decrease in Foxp3+ Tregs in the atherosclerotic lesions, atherosclerotic lesion formation was not significantly affected, suggesting that CCR4-dependent Treg accumulation in atherosclerotic lesions is not critical for prevention of advanced atherosclerosis. Conclusions Our findings indicate an important role for CCR4 in promotion of Treg recruitment into atherosclerotic lesions and subsequent prevention of early atherosclerosis and suggest CCR4 as a novel therapeutic target for atherosclerosis. Funding Acknowledgement Type of funding source: None

Tumors establish resistance to immunotherapy by regulating Treg recruitment via CCR4

BackgroundCheckpoint inhibitors (CPIs) such as anti-PD(L)-1 and anti-CTLA-4 antibodies have resulted in unprecedented rates of antitumor responses and extension of survival of patients with a variety of cancers. But some...

CCR4 Antagonist (C021) Administration Diminishes Hypersensitivity and Enhances the Analgesic Potency of Morphine and Buprenorphine in a Mouse Model of Neuropathic Pain.

Neuropathic pain is a chronic condition that remains a major clinical problem owing to high resistance to available therapy. Recent studies have indicated that chemokine signaling pathways are crucial in the development of painful neuropathy; however, the involvement of CC chemokine receptor 4 (CCR4) has not been fully elucidated thus far. Therefore, the aim of our research was to investigate the role of CCR4 in the development of tactile and thermal hypersensitivity, the effectiveness of morphine/buprenorphine, and opioid-induced tolerance in mice exposed to chronic constriction injury (CCI) of the sciatic nerve. The results of our research demonstrated that a single intrathecal or intraperitoneal administration of C021, a CCR4 antagonist, dose dependently diminished neuropathic pain-related behaviors in CCI-exposed mice. After sciatic nerve injury, the spinal expression of CCL17 and CCL22 remained unchanged in contrast to that of CCL2, which was significantly upregulated until day 14 after CCI. Importantly, our results provide evidence that in naive mice, CCL2 may evoke pain-related behaviors through CCR4 because its pronociceptive effects are diminished by C021. In CCI-exposed mice, the pharmacological blockade of CCR4 enhanced the analgesic properties of morphine/buprenorphine and delayed the development of morphine-induced tolerance, which was associated with the silencing of IBA-1 activation in cells and decrease in CCL2 production. The obtained data suggest that the pharmacological blockade of CCR4 may be a new potential therapeutic target for neuropathic pain polytherapy.

Small molecule antagonist of C-C chemokine receptor 1 (CCR1) reduces disc inflammation in the rabbit model

BACKGROUND CONTEXTTargeting chemokines or chemokine receptors is a promising treatment strategy for diseases with chronic inflammation such as rheumatoid arthritis and discogenic pain. Identifying specific molecules and determining their effectiveness in animal models are the first steps in developing these treatments. Macrophage markers have been detected in the intervertebral disc tissues of patients with disc degenerative disease and discogenic pain and in different animal models. Macrophage recruitment into the disc may play a role in initiation of inflammation and if unresolved may lead to chronic inflammation and subsequent back pain. PURPOSEThe objectives of these studies are to (1) identify chemokine receptor antagonists that can block macrophage migration induced by disc cells in vitro and (2) determine if intradiscal treatment with these antagonists can reduce disc inflammation and degeneration in vivo. STUDY DESIGNIn vitro migration assays were used to test effectiveness of chemokine receptor antagonists to block macrophage migration induced by disc cells. The rabbit annular puncture model was used to test for anti-inflammatory and regenerative effects of chemokine receptor antagonist treatment in vivo. METHODSIn vitro – THP-1 human monocytic cell line and freshly isolated rabbit primary splenocytes were assayed for migration using 3 µm Corning Transwell inserts with conditioned media of interleukin (IL)-1β treated human or rabbit disc cells. Inhibition of macrophage migration was evaluated using different concentrations of small molecule antagonists of C-C chemokine receptor (CCR)1 and CCR2. In vivo – New Zealand White rabbits (n=40) underwent disc puncture and intradiscal treatment with saline, CCR1 or CCR2 antagonists within the same procedure. X-ray and magnetic resonance (MR) images and serum samples were taken for disc height, MRI grade and IL-8 serum level analyses. Intervertebral discs were isolated for RNA analysis of inflammatory and disc phenotypic markers and for immunohistochemical analysis of macrophage marker, RAM11. The outcome measures were compared between the three treatment groups. These studies were funded by a research grant from AO Foundation, Switzerland (Project no S-14-86A; 120000 CHF). CCR1 and CCR2 antagonists were kindly provided by ChemoCentryx (Mountain View, CA). RESULTSIn vitro migration assays showed that THP-1 migration induced by disc cells was blocked by CCR2 antagonist more effectively than CCR1 antagonist, while rabbit splenocyte migration was inhibited by CCR1 antagonist and not the other. In the rabbit annular puncture model, rabbit discs treated with CCR1 antagonist had significantly better MRI grades than those treated with CCR2 antagonist at 6 weeks post-treatment. Gene expression studies demonstrate that discs treated with CCR1 or CCR2 antagonists expressed less inflammatory markers than saline-treated discs at 3 weeks post-treatment. Although CCR2 antagonist treatment did not reduce inflammatory marker expression at 6 weeks, discs treated with CCR1 antagonist expressed less inflammatory markers and also a higher ratio of collagen type 2 to collagen type 1 genes indicating favorable disc matrix production. There were no significant differences between all three treatment groups in regards to disc height indexes, IL-8 serum levels or macrophage marker detection. CONCLUSIONSThese studies have identified that small molecule antagonists against CCR2 and CCR1 were respectively effective in blocking THP-1 and rabbit splenocyte migration induced by disc cells in vitro. Further, both CCR2 and CCR1 antagonist intradiscal treatments were effective in reducing disc inflammation at an early time point of 3 weeks. Lastly, only CCR1 antagonist demonstrated anti-inflammatory effects and better MRI grades at 6 weeks. CLINICAL SIGNIFICANCEOur preclinical studies demonstrate that CCR1 and CCR2 antagonist delivery through intradiscal injection is sufficient to reduce disc inflammation at early time points, whereas CCR1 antagonists had longer term anti-inflammatory effects. Clinical studies have found that CCR1 antagonist was safe, tolerable and clinically active in reducing inflammation in rheumatoid arthritis patients. These studies suggest that CCR1 antagonist may be a promising biological treatment to reduce disc inflammation that translates to back pain relief.

CCR4 antagonist (C021) influences the level of nociceptive factors and enhances the analgesic potency of morphine in a rat model of neuropathic pain

Neuropathic pain is a chronic condition which significantly reduces the quality of life and serious clinical issue that is in general resistant to available therapies. Therefore looking for new analgesics is still critical issue. Recent, studies have indicated that chemokine signaling pathways are crucial for the development of neuropathy; however, the role of CC chemokine receptor 4 (CCR4) in this process has not yet been studied. Therefore, the aim of our research was to investigate the influence of C021 (a CCR4 antagonist) and CCR4 CC chemokine ligands 17 and 22 (CCL17 and CCL22) on the development of hypersensitivity and the effectiveness of morphine induced analgesia in naive animals and/or animals exposed to chronic constriction injury (CCI) of the sciatic nerve. Firstly, we demonstrated that the intrathecal administration of CCL17 and CCL22 induced pain-related behavior in naive mice. Secondly, we revealed that the intrathecal injection of C021 significantly reduced CCI-induced hypersensitivity after nerve injury. In parallel, C021 reduced microglia/macrophages activation and the level of some pronociceptive interleukins (IL-1beta; IL-18) in the spinal cord 8 days after CCI. Moreover, C021 not only attenuated mechanical and thermal hypersensitivity but also enhanced the analgesic properties of morphine. Our research indicates that CCR4 ligands might be important factors in the early stages of neuropathy, when we observe intense microglia/macrophages activation. Moreover, pharmacological blockade of CCR4 may serve as a potential new target for better understanding the mechanisms of neuropathic pain development.

The CCR5 antagonist maraviroc causes remission of pancreatic cancer liver metastasis in nude rats based on cell cycle inhibition and apoptosis induction.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease, and novel therapeutic strategies are urgently needed. Recently, expression of the C-C chemokine receptor 5 (CCR5) and its ligands has been found to play an important role in cancer progression and metastasis. In this study, we blocked the CCR5 receptor by the FDA approved antagonist maraviroc (MVC) in Suit2-007 and MIA-PaCa-2 human PDAC cells. The treatment significantly inhibited their proliferation and induced apoptosis of exposed cells as evidenced by caspases activation and increased Bax levels. Moreover, MVC inhibited the cell cycle by down regulating the proteins of the complexes of cyclin dependent kinase (CDK) 4/6 - Cyclin D and CDK2 - Cyclin E, as well as by increasing the protein levels of CDK inhibitors p18, p21 and p27. In line with this, MVC caused significant retardation of Suit2-007cells growing in a PDAC liver metastasis xenograft model (p<0.05). These results suggest that maraviroc could be a promising treatment strategy for PDAC patients with liver metastases.

R5 HIV-1 gp120 Activates p38 MAPK to Induce Rat Cardiomyocyte Injury by the CCR5 Coreceptor

Background: Effective antiretroviral therapy extends the survival of patients with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome, but these patients remain at higher risk for heart diseases compared with the general population. Previous studies have suggested that HIV-1 glycoprotein 120 (gp120) may be associated with heart disease. However, the underlying mechanisms by which HIV-1 gp120-mediated myocardial injury occurs remain unknown. Objective: The current study aimed to uncover the mechanism of C-C chemokine receptor 5 (CCR5) coreceptor (R5) HIV-1 gp120-induced myocardial injury. Methods: Morphology analysis, determination of the percentage of cell apoptosis, as well as lactate dehydrogenase (LDH) and creatine kinase (CK) assays were used to analyze whether R5 HIV-1 gp120 induced myocardial cell injury. We analyzed the phosphorylation of p38 mitogen-activated protein kinase (MAPK) with the CCR5 antagonist D-Ala-peptide T-amide (DAPTA) and NMDA receptor antagonist MK801, detected LDH and CK assays with p38 MAPK antagonist SB203580 (SB), and detected the percentage of cell apoptosis and death with DAPTA to investigate the mechanism of R5 HIV-1 gp120-induced myocardial cell injury. Results: R5 HIV-1 gp120 damaged myocardial cells and induced p38 MAPK phosphorylation. SB blocked R5 HIV-1 gp120-induced myocardial cell injury. DAPTA blocked R5 HIV-1 gp120-mediated p38 MAPK phosphorylation, while MK801 did not. DAPTA inhibited R5 HIV-1 gp120-induced myocardial cell injury. Conclusion: Our data indicate that R5 HIV-1 gp120 activated p38 MAPK to trigger myocardial cell injury by the CCR5 coreceptor.

Chemokine receptor CCR5 correlates with functional CD8+ T cells in SIV-infected macaques and the potential effects of maraviroc on T-cell activation.

C-C chemokine receptor 5 (CCR5) plays an essential role in HIV pathogenesis as the major coreceptor on CD4+ T cells used by HIV, yet the function of CCR5 on CD8 T cells is not well understood. Furthermore, the immunologic effects of the CCR5 inhibitor maraviroc (MVC), despite approval for clinical use, have not yet been well evaluated for their potential effects on cytotoxic T-cell responses. In this study, we characterized the development and function of CCR5+CD8+ T cells in rhesus macaques with or without Simian immunodeficiency virus (SIV) infection. We also investigated the effects of the CCR5 antagonist MVC on functional CCR5+CD8+ T-cell responses in vitro. The data show that CCR5+CD8+ T cells have an effector memory phenotype and increase with age in systemic and mucosal lymphoid tissues as a heterogeneous population of polyfunctional CD8 T cells. In addition, CCR5 is highly expressed on SIV gag-specific (CM9+) CD8+ T cells in SIV-infected macaques, yet CCR5+CD8+ T cells are significantly reduced in mucosal lymphoid tissues with disease progression. Furthermore, in vitro MVC treatment reduced activation and cytokine secretion of CD8+ T cells via a CCR5-independent pathway. These findings suggest that surface CCR5 protein plays an important role in differentiation and activation of CD8+ T cells. Although MVC may be helpful in reducing chronic inflammation and activation, it may also inhibit virus-specific CD8+ T-cell responses. Thus optimal use of CCR5 antagonists either alone or in combination with other drugs should be defined by further investigation.-Wang, X., Russell-Lodrigue, K. E., Ratterree, M. S., Veazey, R. S., Xu, H. Chemokine receptor CCR5 correlates with functional CD8+ T cells in SIV-infected macaques and the potential effects of maraviroc on T-cell activation.

Structure-Based Design of 1-Heteroaryl-1,3-propanediamine Derivatives as a Novel Series of CC-Chemokine Receptor 5 Antagonists.

CC-chemokine receptor 5 (CCR5) is an attractive target for preventing the entry of human immunodeficiency virus 1 (HIV-1) into human host cells. Maraviroc is the only CCR5 antagonist, and it was marketed in 2007. To overcome the shortcomings of maraviroc, structure-based drug design was performed to minimize CYP450 inhibition and to enhance anti-HIV potency and bioavailability. Thirty-four novel 1-heteroaryl-1,3-propanediamine derivatives (1-34) were synthesized, displaying CCR5-antagonist activities in the 2.3-296.4 nM range. Among these, compounds 21 and 34 were the most potent CCR5 antagonists, with excellent in vitro anti-HIV-1 activity, low cytotoxicity, and an acceptable pharmacokinetic profile. Furthermore, the X-ray crystal structures of compounds 21 and 34 bound to CCR5 were determined at 2.8 Å resolution. Compound 34 exhibited no CYP450-inhibition activity at 25 μM, which overcomes the potential drug-drug interaction of maraviroc. Compound 34 represents a promising drug candidate for HIV-infection treatment.

Blockade of MCP-1/CCR4 signaling-induced recruitment of activated regulatory cells evokes an antitumor immune response in head and neck squamous cell carcinoma.

FoxP3+ regulatory T (Treg) cells have diverse functions in the suppression of antitumor immunity. We show that FoxP3hiCD45RA−CD4+ Treg cells [activated Treg (aTreg) cells] are the predominant cell population among tumor-infiltrating FoxP3+ T cells, and that high aTreg cell-infiltrating content is associated with reduced survival in patients with head and neck squamous cell carcinoma (HNSCC). In vitro studies have demonstrated that aTreg cells can suppress tumor-associated antigen (TAA) effector T cell immune responses in HNSCC. Moreover, C-C chemokine receptor 4 (CCR4) was specifically expressed by aTreg cells in the peripheral blood of HNSCC patients. Using a RayBiotech human chemokine antibody array, we showed that monocyte chemoattractant protein-1 (MCP-1), an endogenous CCR4-binding ligand, was specifically upregulated in the HNSCC microenvironment compared to the other four CCR4-binding ligands. Blocking MCP-1/CCR4 signaling-induced aTreg cell recruitment using a CCR4 antagonist evoked antitumor immunity in mice, and lead to inhibition of tumor growth and prolonged survival. Therefore, blocking aTreg cell trafficking in tumors using CCR4-binding agents may be an effective immunotherapy for HNSCC.

Effects of CC-chemokine receptor 5 on ROCK2 and P-MLC2 expression after focal cerebral ischaemia–reperfusion injury in rats

Objective: CC-chemokine receptor 5 (CCR5) plays a pivotal role in reperfusion after stroke. This study assessed and confirmed the effects of CCR5 in experimental stroke via regulation of ROCK/P-MLC pathway.Methods: Male Sprague Dawley (SD) rats were randomly divided into sham group, ischaemia–reperfusion group (I/R group) and DAPTA group (I/R + CCR5 antagonist group). The rats of the I/R group were subjected to transient middle cerebral artery occlusion (tMCAO) for 2 hours, followed by 24 hours of reperfusion. Animals were measured for neurologic deficit, cerebral infarct volume, TUNEL and hematoxylin-eosin (HE) staining. The protein expressions of ROCK2 and P-MLC2(Ser19) were determined by western blot.Results: Pre-treatment with DAPTA displayed significantly improved neurological functional outcome and reduced cerebral lesion compared with the I/R group animals (p < 0.05); HE staining showed that the I/R group had severe neuronal damage in the ischaemia core and penumbral; Compared with the I/R group, ROCK2 and P-MLC2(Ser19) protein expression in the DAPTA group was reduced (p < 0.05).Conclusions: The data demonstrate that CCR5 is correlated with up-regulation of the expression of ROCK2 and P-MLC2(Ser19) in the ischaemia cortex. Treated with CCR5 antagonist protects the brain against focal cerebral ischaemia–reperfusion injury in rats.

CCR5 deficiency accelerates lipopolysaccharide-induced astrogliosis, amyloid-beta deposit and impaired memory function

Chemokine receptors are implicated in inflammation and immune responses. Neuro-inflammation is associated with activation of astrocyte and amyloid-beta (Aβ) generations that lead to pathogenesis of Alzheimer disease (AD). Previous our study showed that deficiency of CC chemokine receptor 5 (CCR5) results in activation of astrocytes and Aβ deposit, and thus memory dysfunction through increase of CC chemokine receptor 2 (CCR2) expression. CCR5 knockout mice were used as an animal model with memory dysfunction. For the purpose LPS was injected i.p. daily (0.25 mg/kg/day). The memory dysfunctions were much higher in LPS-injected CCR5 knockout mice compared to CCR5 wild type mice as well as non-injected CCR5 knockout mice. Associated with severe memory dysfuction in LPS injected CCR5 knockout mice, LPS injection significant increase expression of inflammatory proteins, astrocyte activation, expressions of β-secretase as well as Aβ deposition in the brain of CCR5 knockout mice as compared with that of CCR5 wild type mice. In CCR5 knockout mice, CCR2 expressions were high and co-localized with GFAP which was significantly elevated by LPS. Expression of monocyte chemoattractant protein-1 (MCP-1) which ligands of CCR2 also increased by LPS injection, and increment of MCP-1 expression is much higher in CCR5 knockout mice. BV-2 cells treated with CCR5 antagonist, D-ala-peptide T-amide (DAPTA) and cultured astrocytes isolated from CCR5 knockout mice treated with LPS (1 μg/ml) and CCR2 antagonist, decreased the NF-ĸB activation and Aβ level. These findings suggest that the deficiency of CCR5 enhances response of LPS, which accelerates to neuro-inflammation and memory impairment.

Developing Adnectins That Target SRC Co-Activator Binding to PXR: A Structural Approach toward Understanding Promiscuity of PXR

The human pregnane X receptor (PXR) is a promiscuous nuclear receptor that functions as a sensor to a wide variety of xenobiotics and regulates expression of several drug metabolizing enzymes and transporters. We have generated “Adnectins”, derived from 10th fibronectin type III domain (10Fn3), that target the PXR ligand binding domain (LBD) interactions with the steroid receptor co-activator-1 (SRC-1) peptide, displacing SRC-1 binding. Adnectins are structurally homologous to the immunoglobulin superfamily. Three different co-crystal structures of PXR LBD with Adnectin-1 and CCR1 (CC chemokine receptor-1) antagonist Compound-1 were determined. This structural information was used to modulate PXR affinity for a related CCR1 antagonist compound that entered into clinical trials for rheumatoid arthritis. The structures of PXR with Adnectin-1 reveal specificity of Adnectin-1 in not only targeting the interface of the SRC-1 interactions but also engaging the same set of residues that are involved in binding of SRC-1 to PXR. Substituting SRC-1 with Adnectin-1 does not alter the binding conformation of Compound-1 in the ligand binding pocket. The structure also reveals the possibility of using Adnectins as crystallization chaperones to generate structures of PXR with compounds of interest.

Maraviroc Attenuates Trauma-Hemorrhage-Induced Hepatic Injury through PPAR Gamma-Dependent Pathway in Rats

Maraviroc is a CC-chemokine receptor 5 (CCR5) antagonist with potent antiviral and cancer preventive effects. Recent evidence suggests that the co-existence of CCR5 in various cell types is involved in inflammation. However, the effects that CCR5 antagonists produce in trauma-hemorrhage remain unknown. The peroxisome proliferator-activated receptor gamma (PPARγ) pathway exerts anti-inflammatory effects in injury. In this study, we hypothesized that maraviroc administration in male rats, after trauma-hemorrhage, decreases cytokine production and protects against hepatic injury through a PPARγ-dependent pathway. Male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure maintained at approximately 35-40 mmHg for 90 minutes), followed by fluid resuscitation. During resuscitation, a single dose of maraviroc (3 mg/kg, intravenously) with and without a PPARγ antagonist GW9662 (1 mg/kg, intravenously), GW9662 or vehicle was administered. Plasma alanine aminotransferase (ALT) with aspartate aminotransferase (AST) concentrations and various hepatic parameters were measured (n=8 rats/group) at 24 hours after resuscitation. The results showed that trauma-hemorrhage increased hepatic myeloperoxidase activity, intercellular adhesion molecule-1 and interleukin-6 levels, and plasma ALT and AST concentrations. These parameters were significantly improved in the maraviroc-treated rats subjected to trauma-hemorrhage. Maraviroc treatment also increased hepatic PPARγ expression compared with vehicle-treated trauma-hemorrhaged rats. Co-administration of GW9662 with maraviroc abolished the maraviroc-induced beneficial effects on the above parameters and hepatic injury. These results suggest that the protective effect of maraviroc administration on alleviation of hepatic injury after trauma-hemorrhage, which is, at least in part, through PPARγ-dependent pathway.