Molecular cloning and functional expression of a novel CC chemokine receptor cDNA from a human basophilic cell line

CCR4 Blockade Diminishes Intratumoral Macrophage Recruitment and Augments Survival of Syngeneic Pancreatic Cancer-Bearing Mice

Pancreatic cancer is known for its tumor microenvironment (TME), which is rich in stromal and immune cells supporting cancer growth and therapy resistance. In particular, tumor-associated macrophages (TAMs) are known for their angiogenesis- and metastasis-promoting properties, which lead to the failure of conventional therapies for pancreatic cancer. Hence, treatment options targeting TAMs are needed. The C-C chemokine receptor type 4 (CCR4) is critical for immune cell recruitment into the TME, and in this paper we explore the effects of its genetic or immunotherapeutic blockade in pancreatic-cancer-bearing mice. Murine PDA6606 pancreatic cancer cells and murine peritoneal macrophages were used for in vitro migration assays. In vivo, a syngeneic, orthotropic pancreatic cancer model was established. Tumor growth and survival were monitored under prophylactic and therapeutic application of a CCR4 antagonist (AF-399/420/18025) in wildtype (CCR4^wt) and CCR4-knockout (CCR4^-/-) mice. Immune infiltration was monitored in tumor tissue sections and via flow cytometry of lysed tumors. PDA6606 cells induced less migration in CCR4^-/- than in CCR4^wt macrophages in vitro. Pancreatic TAM infiltration was higher, and survival was reduced in CCR4^wt mice compared to CCR4^-/- mice. Antagonizing CCR4 in wildtype mice revealed similar results as in CCR4^-/- mice without antagonization. Prophylactic CCR4 antagonist application in wildtype mice was more efficient than therapeutic antagonization. CCR4 seems to be critically involved in TAM generation and tumor progression in pancreatic cancer. CCR4 blockade may help prolong the relapse-free period after curative surgery in pancreatic cancer and improve prognosis.

CC Chemokine Receptor 4 (CCR4) as a Possible New Target for Therapy

Chemokines and their receptors participate in many biological processes, including the modulation of neuroimmune interactions. Approximately fifty chemokines are distinguished in humans, which are classified into four subfamilies based on the N-terminal conserved cysteine motifs: CXC, CC, C, and CX3C. Chemokines activate specific receptors localized on the surface of various immune and nervous cells. Approximately twenty chemokine receptors have been identified, and each of these receptors is a seven-transmembrane G-protein coupled receptor. Recent studies provide new evidence that CC chemokine receptor 4 (CCR4) is important in the pathogenesis of many diseases, such as diabetes, multiple sclerosis, asthma, dermatitis, and cancer. This review briefly characterizes CCR4 and its ligands (CCL17, CCL22, and CCL2), and their contributions to immunological and neoplastic diseases. The review notes a significant role of CCR4 in nociceptive transmission, especially in painful neuropathy, which accompanies many diseases. The pharmacological blockade of CCR4 seems beneficial because of its pain-relieving effects and its influence on opioid efficacy. The possibilities of using the CCL2/CCL17/CCL22/CCR4 axis as a target in new therapies for many diseases are also discussed.

Therapeutic Mechanism and Key Alkaloids of Uncaria rhynchophylla in Alzheimer’s Disease From the Perspective of Pathophysiological Processes

Presently, there is a lack of effective disease-modifying drugs for the treatment of Alzheimer’s disease (AD). Uncaria rhynchophylla (UR) and its predominant active phytochemicals alkaloids have been studied to treat AD. This study used a novel network pharmacology strategy to identify UR alkaloids against AD from the perspective of AD pathophysiological processes and identified the key alkaloids for specific pathological process. The analysis identified 10 alkaloids from UR based on high-performance liquid chromatography (HPLC) that corresponded to 127 targets correlated with amyloid-β (Aβ) pathology, tau pathology and Alzheimer disease pathway. Based on the number of targets correlated with AD pathophysiological processes, angustoline, angustidine, corynoxine and isocorynoxeine are highly likely to become key phytochemicals in AD treatment. Among the 127 targets, JUN, STAT3, MAPK3, CCND1, MMP2, MAPK8, GSK3B, JAK3, LCK, CCR5, CDK5 and GRIN2B were identified as core targets. Based on the pathological process of AD, angustoline, angustidine and isocorynoxeine were identified as the key UR alkaloids regulating Aβ production and corynoxine, isocorynoxeine, dihydrocorynatheine, isorhynchophylline and hirsutine were identified as key alkaloids that regulate tau phosphorylation. The findings of this study contribute to a more comprehensive understanding of the key alkaloids and mechanisms of UR in the treatment of AD, as well as provide candidate compounds for drug research and development for specific AD pathological processes.

CCR4 as a Therapeutic Target for Cancer Immunotherapy

Simple Summary

CCR4 is a chemokine receptor selectively expressed on normal T cell subsets such as type 2 helper T cells, skin-homing T cells and regulatory T cells, and on skin-associated T cell malignancies such as adult T cell leukemia/lymphoma (ATLL), which is etiologically associated with human T lymphocyte virus type 1 (HTLV-1), and cutaneous T cell lymphomas (CTCLs). Mogamulizumab is a fully humanized and glyco-engineered monoclonal anti-CCR4 antibody used for the treatment of refractory/relapsed ATLL and CTCLs, often resulting in complete remission. The clinical applications of Mogamulizumab are now being extended to solid tumors, exploring the therapeutic effect of regulatory T cell depletion. This review overviews the expression of CCR4 in various T cell subsets, HTLV-1-infected T cells, ATLL and CTCLs, and the clinical applications of Mogamulizumab.

Abstract

CCR4 is a chemokine receptor mainly expressed by T cells. It is the receptor for two CC chemokine ligands, CCL17 and CCL22. Originally, the expression of CCR4 was described as highly selective for helper T type 2 (Th2) cells. Later, its expression was extended to other T cell subsets such as regulatory T (Treg) cells and Th17 cells. CCR4 has long been regarded as a potential therapeutic target for allergic diseases such as atopic dermatitis and bronchial asthma. Furthermore, the findings showing that CCR4 is strongly expressed by T cell malignancies such as adult T cell leukemia/lymphoma (ATLL) and cutaneous T cell lymphomas (CTCLs) have led to the development and clinical application of the fully humanized and glyco-engineered monoclonal anti-CCR4 Mogamulizumab in refractory/relapsed ATLL and CTCLs with remarkable successes. However, Mogamulizumab often induces severe adverse events in the skin possibly because of its efficient depletion of Treg cells. In particular, treatment with Mogamulizumab prior to allogenic hematopoietic stem cell transplantation (allo-HSCT), the only curative option of these T cell malignancies, often leads to severe glucocorticoid-refractory graft-versus-host diseases. The efficient depletion of Treg cells by Mogamulizumab has also led to its clinical trials in advanced solid tumors singly or in combination with immune checkpoint inhibitors. The main focus of this review is CCR4; its expression on normal and malignant T cells and its significance as a therapeutic target in cancer immunotherapy.

Virus-Driven Carcinogenesis

Cancer arises from the accumulation of genetic and epigenetic alterations. Even in the era of precision oncology, carcinogens contributing to neoplastic process are still an important focus of research. Comprehensive genomic analyses have revealed various combinations of base substitutions, referred to as the mutational signatures, in cancer. Each mutational signature is believed to arise from specific DNA damage and repair processes, including carcinogens. However, as a type of carcinogen, tumor viruses increase the cancer risk by alternative mechanisms, including insertional mutagenesis, viral oncogenes, and immunosuppression. In this review, we summarize virus-driven carcinogenesis to provide a framework for the control of malignant cell proliferation. We first provide a brief overview of oncogenic viruses and describe their implication in virus-related tumors. Next, we describe tumor viruses (HPV, Human papilloma virus; HBV, Hepatitis B virus; HCV, Hepatitis C virus; EBV, Epstein-Barr virus; Kaposi sarcoma herpesvirus; MCV, Merkel cell polyoma virus; HTLV-1, Human T-cell lymphotropic virus, type-1) and tumor virus-related cancers. Lastly, we introduce emerging tumor virus candidates, human cytomegalovirus (CMV), human herpesvirus-6 (HHV-6) and adeno-associated virus-2 (AAV-2). We expect this review to be a hub in a complex network of data for virus-associated carcinogenesis.

CCL3 contributes to secondary damage after spinal cord injury

Background

Secondary damage after spinal cord injury (SCI) is characterized by a cascade of events including hemorrhage, apoptosis, oxidative stress, and inflammation which increase the lesion size which can influence the functional impairment. Thus, identifying specific mechanisms attributed to secondary injury is critical in minimizing tissue damage and improving neurological outcome. In this work, we are investigating the role of CCL3 (macrophage inflammatory protein 1-α, MIP-1α), a chemokine involved in the recruitment of inflammatory cells, which plays an important role in inflammatory conditions of the central and peripheral nervous system.

Methods

A mouse model of lower thoracic (T11) spinal cord contusion injury was used. We assessed expression levels of CCL3 and its receptors on the mRNA and protein level and analyzed changes in locomotor recovery and the inflammatory response in the injured spinal cord of wild-type and CCL3^−/− mice.

Results

The expression of CCL3 and its receptors was increased after thoracic contusion SCI in mice. We then examined the role of CCL3 after SCI and its direct influence on the inflammatory response, locomotor recovery and lesion size using CCL3^−/− mice. CCL3^−/− mice showed mild but significant improvement of locomotor recovery, a smaller lesion size and reduced neuronal damage compared to wild-type controls. In addition, neutrophil numbers as well as the pro-inflammatory cytokines and chemokines, known to play a deleterious role after SCI, were markedly reduced in the absence of CCL3.

Conclusion

We have identified CCL3 as a potential target to modulate the inflammatory response and secondary damage after SCI. Collectively, this study shows that CCL3 contributes to progressive tissue damage and functional impairment during secondary injury after SCI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-020-02037-3.

Association of the CCR5Δ32 Mutant Genotype with Sickle Cell Disease in Egyptian Patients

Sickle cell disease is considered the most common single base mutation in the world, with >250,000 new patients being discovered each year. It consists of a wide spectrum of clinical presentations and complications. The CCR5Δ32 is the mutant genotype of C-C chemokine receptor 5 (CCR5). It is widely distributed due to several micro organisms that target macrophages in different populations. Theoretically, CCR5Δ32 confers an advantage to sickle cell disease patients. The chronic inflammatory response is the main pathogenesis in sickle cell disease, thus, the presence of the null CCR5Δ32 mutant genotype prevents the Th1-type immune response caused by the CCR5 chemokine receptor. This study aimed to define the true incidence of the CCR5Δ32 mutant genotype and to correlate its presence with the clinical and/or the radiological findings in sickle cell disease patients. We proposed decreased morbidity and prolonged survival of sickle cell disease patients carrying the CCR5Δ32 genotype. The study showed relatively the same prevalence (5.1%) of the CCR5Δ32 mutant genotype found in 500 sickle cell disease patients when compared to 1000 healthy controls (5.0%) with the same ethnic background. Despite the near prevalence of the incidence to controls, we suggest that CCR5Δ32 is relatively beneficial to sickle cell disease patients as polymorphic patients showed uncomplicated clinical presentation in contrast to other patients without the CCR5Δ32.

Entanglement of CCR5 and Alzheimer's Disease

Although the mechanisms of Alzheimer's disease are diverse and unclear, the past 20 years have witnessed the unprecedented development of the AD inflammation theory. As a key inflammatory receptor family, the C-C chemokine receptor family is a remarkable participant in the cause of Alzheimer's disease; of this family, CCR5 is the most widely studied. CCR5 is an essential entrance when HIV infects immune cells and is also involved in other inflammatory and immune activities. New evidence on the inevitably intertwined link between Alzheimer's disease and CCR5 indicates that CCR5 accelerates the development of Alzheimer's disease, and few studies disputed it. The role of CCR5 in Alzheimer's disease remains elusive. However, as the research progresses, this intricate relationship will gradually be uncovered.

The emergence of pathogenic TNF/iNOS producing dendritic cells (Tip-DCs) in a malaria model of acute respiratory distress syndrome (ARDS) is dependent on CCR4

Malaria-associated acute respiratory distress syndrome (MA-ARDS) and acute lung injury (ALI) are complications that cause lung damage and often leads to death. The MA-ARDS/ALI is associated with a Type 1 inflammatory response mediated by T lymphocytes and IFN-γ. Here, we used the Plasmodium berghei NK65 (PbN)-induced MA-ALI/ARDS model that resembles human disease and confirmed that lung CD4⁺ and CD8⁺ T cells predominantly expressed Tbet and IFN-γ. Surprisingly, we found that development of MA-ALI/ARDS was dependent on functional CCR4, known to mediate the recruitment of Th2 lymphocytes and regulatory T cells. However, in this Type 1 inflammation-ARDS model, CCR4 was not involved in the recruitment of T lymphocytes, but was required for the emergence of TNF-α/iNOS producing dendritic cells (Tip-DCs) in the lungs. In contrast, recruitment of Tip-DCs and development of MA-ALI/ARDS were not altered in CCR2^-/- mice. Importantly, we showed that NOS2^-/- mice are resistant to PbN-induced lung damage, indicating that reactive nitrogen species produced by Tip-DCs play an essential role in inducing MA-ARDS/ALI. Lastly, our experiments suggest that production of IFN-γ primarily by CD8⁺ T cells is required for inducing Tip-DCs differentiation in the lungs and the development of MA-ALI/ARDS model.

Macrophage biology in the peripheral nervous system after injury

Neuroinflammation has positive and negative effects. This review focuses on the roles of macrophage in the PNS. Transection of PNS axons leads to degeneration and clearance of the distal nerve and to changes in the region of the axotomized cell bodies. In both locations, resident and infiltrating macrophages are found. Macrophages enter these areas in response to expression of the chemokine CCL2 acting on the macrophage receptor CCR2. In the distal nerve, macrophages and other phagocytes are involved in clearance of axonal debris, which removes molecules that inhibit nerve regeneration. In the cell body region, macrophage trigger the conditioning lesion response, a process in which neurons increase their regeneration after a prior lesion. In mice in which the genes for CCL2 or CCR2 are deleted, neither macrophage infiltration nor the conditioning lesion response occurs in dorsal root ganglia (DRG). Macrophages exist in different phenotypes depending on their environment. These phenotypes have different effects on axonal clearance and neurite outgrowth. The mechanism by which macrophages affect neuronal cell bodies is still under study. Overexpression of CCL2 in DRG in uninjured animals leads to macrophage accumulation in the ganglia and to an increase in the growth potential of DRG neurons. This increased growth requires activation of neuronal STAT3. In contrast, in acute demyelinating neuropathies, macrophages are involved in stripping myelin from peripheral axons. The molecular mechanisms that trigger macrophage action after trauma and in autoimmune disease are receiving increased attention and should lead to avenues to promote regeneration and protect axonal integrity.

Histone H3 Serine 10 Phosphorylation Facilitates Endothelial Activation in Diabetic Kidney Disease

The posttranslational histone modifications that epigenetically affect gene transcription extend beyond conventionally studied methylation and acetylation patterns. By examining the means by which podocytes influence the glomerular endothelial phenotype, we identified a role for phosphorylation of histone H3 on serine residue 10 (phospho-histone H3Ser10) in mediating endothelial activation in diabetes. Culture media conditioned by podocytes exposed to high glucose caused glomerular endothelial vascular cell adhesion protein 1 (VCAM-1) upregulation and was enriched for the chemokine CCL2. A neutralizing anti-CCL2 antibody prevented VCAM-1 upregulation in cultured glomerular endothelial cells, and knockout of the CCL2 receptor CCR2 diminished glomerular VCAM-1 upregulation in diabetic mice. CCL2/CCR2 signaling induced glomerular endothelial VCAM-1 upregulation through a pathway regulated by p38 mitogen-activated protein kinase, mitogen- and stress-activated protein kinases 1/2 (MSK1/2), and phosphorylation of H3Ser10, whereas MSK1/2 inhibition decreased H3Ser10 phosphorylation at the VCAM1 promoter. Finally, increased phospho-histone H3Ser10 levels were observed in the kidneys of diabetic endothelial nitric oxide synthase knockout mice and in the glomeruli of humans with diabetic kidney disease. These findings demonstrate the influence that histone protein phosphorylation may have on gene activation in diabetic kidney disease. Histone protein phosphorylation should be borne in mind when considering epigenetic targets amenable to therapeutic manipulation in diabetes.

The C-C Chemokines CCL17 and CCL22 and Their Receptor CCR4 in CNS Autoimmunity

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). It affects more than two million people worldwide, mainly young adults, and may lead to progressive neurological disability. Chemokines and their receptors have been shown to play critical roles in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a murine disease model induced by active immunization with myelin proteins or transfer of encephalitogenic CD4⁺ T cells that recapitulates clinical and neuropathological features of MS. Chemokine ligand-receptor interactions orchestrate leukocyte trafficking and influence multiple pathophysiological cellular processes, including antigen presentation and cytokine production by dendritic cells (DCs). The C-C class chemokines 17 (CCL17) and 22 (CCL22) and their C-C chemokine receptor 4 (CCR4) have been shown to play an important role in homeostasis and inflammatory responses. Here, we provide an overview of the involvement of CCR4 and its ligands in CNS autoimmunity. We review key clinical studies of MS together with experimental studies in animals that have demonstrated functional roles of CCR4, CCL17, and CCL22 in EAE pathogenesis. Finally, we discuss the therapeutic potential of newly developed CCR4 antagonists and a humanized anti-CCR4 antibody for treatment of MS.

CCL2 recruits T cells into the brain in a CCR2-independent manner

CCL2 is a chemokine that can be induced during neuroinflammation to recruit immune cells, but its role in the central nervous system (CNS) is unclear. Our aim was to better understand its role. We induced CCL2 in CNS of naive CCL2-deficient mice using intrathecally administered replication-defective adenovirus and examined cell infiltration by flow cytometry. CCL2 expression induced pronounced and unexpected recruitment of regulatory and IFNγ-producing T cells to CNS from blood, possibly related to defective egress of monocytes from CCL2-deficient bone marrow. Infiltration also occurred in mice lacking CCR2, a receptor for CCL2. Expression of another receptor for CCL2, CCR4, and CXCR3, a receptor for CXCL10, which was also induced, were both increased in CCL2-treated CNS. CCR4 was expressed by neurons and astrocytes as well as CD4 T cells, and CXCR3 was expressed by CD4 and CD8 T cells. Chemokine-recruited T cells did not lead to CNS pathology. Our findings show a role for CCL2 in recruitment of CD4 T cells to the CNS and show that redundancy among chemokine receptors ensures optimal response.

CCL2/Monocyte Chemoattractant Protein 1 and Parathyroid Hormone Action on Bone

Chemokines are small molecules that play a crucial role as chemoattractants for several cell types, and their components are associated with host immune responses and repair mechanisms. Chemokines selectively recruit monocytes, neutrophils, and lymphocytes and induce chemotaxis through the activation of G protein-coupled receptors. Two well-described chemokine families (CXC and CC) are known to regulate the localization and trafficking of immune cells in cases of injury, infection, and tumors. Monocyte chemoattractant protein 1 (MCP-1/CCL2) is one of the important chemokines from the CC family that controls migration and infiltration of monocytes/macrophages during inflammation. CCL2 is profoundly expressed in osteoporotic bone and prostate cancer-induced bone resorption. CCL2 also regulates physiological bone remodeling in response to hormonal and mechanical stimuli. Parathyroid hormone (PTH) has multifaceted effects on bone, depending on the mode of administration. Intermittent PTH increases bone in vivo by increasing the number and activity of osteoblasts, whereas a continuous infusion of PTH decreases bone mass by stimulating a net increase in bone resorption. CCL2 is essential for both anabolic and catabolic effects of PTH. In this review, we will discuss the pharmacological role of PTH and involvement of CCL2 in the processes of PTH-mediated bone remodeling.

C-C Motif Chemokine 5 Attenuates Angiotensin II-Dependent Kidney Injury by Limiting Renal Macrophage Infiltration

Inappropriate activation of the renin angiotensin system (RAS) is a key contributor to the pathogenesis of essential hypertension. During RAS activation, infiltration of immune cells into the kidney exacerbates hypertension and renal injury. However, the mechanisms underpinning the accumulation of mononuclear cells in the kidney after RAS stimulation remain unclear. C-C motif chemokine 5 (CCL5) drives recruitment of macrophages and T lymphocytes into injured tissues, and we have found that RAS activation induces CCL5 expression in the kidney during the pathogenesis of hypertension and renal fibrosis. We therefore evaluated the contribution of CCL5 to renal damage and fibrosis in hypertensive and normotensive models of RAS stimulation. Surprisingly, during angiotensin II-induced hypertension, CCL5-deficient (knockout, KO) mice exhibited markedly augmented kidney damage, macrophage infiltration, and expression of proinflammatory macrophage cytokines compared with wild-type controls. When subjected to the normotensive unilateral ureteral obstruction model of endogenous RAS activation, CCL5 KO mice similarly developed more severe renal fibrosis and greater accumulation of macrophages in the kidney, congruent with enhanced renal expression of the macrophage chemokine CCL2. In turn, pharmacologic inhibition of CCL2 abrogated the differences between CCL5 KO and wild-type mice in kidney fibrosis and macrophage infiltration after unilateral ureteral obstruction. These data indicate that CCL5 paradoxically limits macrophage accumulation in the injured kidney during RAS activation by constraining the proinflammatory actions of CCL2.

Targeting chemokine receptors in disease--a case study of CCR4

Since their early 1990s, the chemokine receptor family of G protein-coupled receptors (GPCRs) has been the source of much pharmacological endeavour. Best known for their key roles in recruiting leukocytes to sites of infection and inflammation, the receptors present themselves as plausible drug targets for therapeutic intervention. In this article, we will focus our attention upon CC Chemokine Receptor Four (CCR4) which has been implicated in diseases as diverse as allergic asthma and lymphoma. We will review the discovery of the receptors and their ligands, their perceived roles in disease and the successful targeting of CCR4 by both small molecule antagonists and monoclonal antibodies. We will also discuss future directions and strategies for drug discovery in this field.

Quantitative mass spectrometric immunoassay for the chemokine RANTES and its variants

The chemokine RANTES plays a key role in inflammation, cell recruitment and T cell activation. RANTES is heterogenic and exists as multiple variants in vivo. Herein we describe the development and characterization of a fully quantitative mass spectrometric immunoassay (MSIA) for analysis of intact RANTES and its proteoforms in human serum and plasma samples. The assay exhibits linearity over a wide concentration range (1.56-200ng/mL), intra- and inter-assay precision with CVs <10%, and good linearity and recovery correlations. The assay was tested in different biological matrices, and it was benchmarked against an existing RANTES ELISA. The new RANTES MSIA was used to analyze RANTES and its proteoforms in a small clinical cohort, revealing the quantitative distribution and frequency of the native and truncated RANTES proteoforms.

BIOLOGICAL SIGNIFICANCE

In the last two decades, RANTES has been studied extensively due to its association with numerous clinical conditions, including kidney-related, autoimmune, cardiovascular, viral and metabolic pathologies. Although a single gene product, RANTES is expressed in a range of cells and tissues presenting with different endogenously produced variants and PTMs. The structural variety and population diversity that has been identified for RANTES necessitate developing advanced methodologies that can provide insight into the protein heterogeneity and its function and regulation in disease. In this work we present a simple, efficient and high-throughput mass spectrometric immunoassay (MSIA) method for analysis of RANTES proteoforms. RANTES MSIA can detect and analyze RANTES proteoforms and provide an insight into the endogenous protein modifications.

Mogamulizumab and the treatment of CCR4-positive T-cell lymphomas

Glyco-engineering has been developed to enhance the pharmacological properties of monoclonal antibodies (mAbs) resulting in superior immune effector function. Mogamulizumab is the first approved glyco-engineered therapeutic antibody and first approved mAb to target the CC chemokine receptor 4 (CCR4). CCR4 is principally expressed on Tregs and helper T cells (Th) where it functions to induce homing of these leukocytes to sites of inflammation. Tregs play an essential role in maintaining immune balance; however, in malignancy, Tregs impair host antitumor immunity and provide a favorable environment for tumors to grow. CCR4 is highly expressed by aggressive peripheral T-cell lymphomas (PTCLs), particularly adult T-cell leukemia/lymphoma (ATL) and cutaneous T-cell lymphomas (CTCLs). Mogamulizumab is a humanized anti-CCR4 mAb with a defucosylated Fc region that enhances antibody-dependent cellular cytotoxicity (ADCC). In addition, mogamulizumab depletes CCR4+ Tregs, potentially evoking antitumor immune responses by autologous effector cells. This ability is highly pertinent as subsets of malignant T cells are believed to function as CD4+ Tregs, overexpressing CCR4. Clinical trials with mogamulizumab have demonstrated clinical efficacy and tolerability for the treatment of relapsed/refractory aggressive T-cell lymphomas, previously associated with very poor outcomes.

Recombinant human interleukin-1 receptor antagonist in severe traumatic brain injury: a phase II randomized control trial

Traumatic brain injury (TBI) is the commonest cause of death and disability in those aged under 40 years. Interleukin-1 receptor antagonist (IL1ra) is an endogenous competitive antagonist at the interleukin-1 type-1 receptor (IL-1R). Antagonism at the IL-1R confers neuroprotection in several rodent models of neuronal injury (i.e., trauma, stroke and excitotoxicity). We describe a single center, phase II, open label, randomized-control study of recombinant human IL1ra (rhIL1ra, anakinra) in severe TBI, at a dose of 100 mg subcutaneously once a day for 5 days in 20 patients randomized 1:1. We provide safety data (primary outcome) in this pathology, utilize cerebral microdialysis to directly determine brain extracellular concentrations of IL1ra and 41 cytokines and chemokines, and use principal component analysis (PCA) to explore the resultant cerebral cytokine profile. Interleukin-1 receptor antagonist was safe, penetrated into plasma and the brain extracellular fluid. The PCA showed a separation in cytokine profiles after IL1ra administration. A candidate cytokine from this analysis, macrophage-derived chemoattractant, was significantly lower in the rhIL1ra-treated group. Our results provide promising data for rhIL1ra as a therapeutic candidate by showing safety, brain penetration and a modification of the neuroinflammatory response to TBI by a putative neuroprotective agent in humans for the first time.

Distinct conformations of the chemokine receptor CCR4 with implications for its targeting in allergy

CC chemokine receptor 4 (CCR4) is expressed by Th2 and regulatory T cells and directs their migration along gradients of the chemokines CCL17 and CCL22. Both chemokines and receptor are upregulated in allergic disease, making CCR4 a therapeutic target for the treatment of allergy. We set out to assess the mechanisms underlying a previous report that CCL22 is a dominant ligand of CCR4, which may have implications for its therapeutic targeting. Human T cells expressing endogenous CCR4 and transfectants engineered to express CCR4 were assessed for receptor function, using assays of calcium release, chemotaxis, receptor endocytosis, and ligand binding. Despite the two ligands having equal potency in calcium flux and chemotaxis assays, CCL22 showed dominance in both receptor endocytosis assays and heterologous competitive binding assays. Using two different CCR4-specific Abs, we showed that CCR4 exists in at least two distinct conformations, which are differentially activated by ligand. A major population is activated by both CCL17 and CCL22, whereas a minor population is activated only by CCL22. Mutation of a single C-terminal residue K310 within a putative CCR4 antagonist binding site ablated activation of CCR4 by CCL17, but not by CCL22, despite having no effect on the binding of either ligand. We conclude that CCL17 and CCL22 are conformationally selective ligands of CCR4 and interact with the receptor by substantially different mechanisms. This finding suggests that the selective blockade of CCR4 in allergy may be feasible when one CCR4 ligand dominates, allowing the inhibition of Th2 signaling via one ligand while sparing regulatory T cell recruitment via another.

Internalization of the chemokine receptor CCR4 can be evoked by orthosteric and allosteric receptor antagonists

The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to β-arrestin and stimulated GTPγS binding however CCL17 did not couple to β-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.

TH1/TH2 cell differentiation and molecular signals

The distinctive differentiated states of the CD4+ T helper cells are determined by the set of transcription factors and the genes transcribed by the transcription factors. In vitro induction models, the major determinants of the cytokines present during the T-cell receptor (TCR)-mediated activation process. IL-12 and IFN-γ make Naive CD4+ T cells highly express T-bet and STAT4 and differentiate to TH1 cells, while IL-4 make Naive CD4+ T cells highly express STAT6 and GATA3 and differentiated to TH2 cells. Even through T-bet and GATA3 are master regulators for TH1/TH2 cells differentiation. There are many other transcription factors, such as RUNX family proteins, IRF4, Dec2, Gfi1, Hlx, and JunB that can impair TH1/TH2 cells differentiation. In recent years, noncoding RNAs (microRNA and long noncoding RNA) join in the crowd. The leukocytes should migrate to the right place to show their impact. There are some successful strategies, which are revealed to targeting chemokines and their receptors, that have been developed to treat human immune-related diseases.

International Union of Basic and Clinical Pharmacology. [corrected]. LXXXIX. Update on the extended family of chemokine receptors and introducing a new nomenclature for atypical chemokine receptors

Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.

CC chemokine receptors and chronic inflammation--therapeutic opportunities and pharmacological challenges

Chemokines are a family of low molecular weight proteins with an essential role in leukocyte trafficking during both homeostasis and inflammation. The CC class of chemokines consists of at least 28 members (CCL1-28) that signal through 10 known chemokine receptors (CCR1-10). CC chemokine receptors are expressed predominantly by T cells and monocyte-macrophages, cell types associated predominantly with chronic inflammation occurring over weeks or years. Chronic inflammatory diseases including rheumatoid arthritis, atherosclerosis, and metabolic syndrome are characterized by continued leukocyte infiltration into the inflammatory site, driven in large part by excessive chemokine production. Over years or decades, persistent inflammation may lead to loss of tissue architecture and function, causing severe disability or, in the case of atherosclerosis, fatal outcomes such as myocardial infarction or stroke. Despite the existence of several clinical strategies for targeting chronic inflammation, these diseases remain significant causes of morbidity and mortality globally, with a concomitant economic impact. Thus, the development of novel therapeutic agents for the treatment of chronic inflammatory disease continues to be a priority. In this review we introduce CC chemokine receptors as critical mediators of chronic inflammatory responses and explore their potential role as pharmacological targets. We discuss functions of individual CC chemokine receptors based on in vitro pharmacological data as well as transgenic animal studies. Focusing on three key forms of chronic inflammation--rheumatoid arthritis, atherosclerosis, and metabolic syndrome--we describe the pathologic function of CC chemokine receptors and their possible relevance as therapeutic targets.

Development of operational models of receptor activation including constitutive receptor activity and their use to determine the efficacy of the chemokine CCL17 at the CC chemokine receptor CCR4

BACKGROUND AND PURPOSE The operational model provides a key conceptual framework for the analysis of pharmacological data. However, this model does not include constitutive receptor activity, a frequent phenomenon in modern pharmacology, particularly in recombinant systems. Here, we developed extensions of the operational model which include constitutive activity and applied them to effects of agonists at the chemokine receptor CCR4. EXPERIMENTAL APPROACH The effects of agonists of CCR4 on [(35) S]GTPγS binding to recombinant cell membranes and on the filamentous (F-) actin content of human CD4(+) CCR4(+) T cells were determined. The basal [(35) S]GTPγS binding was changed by varying the GDP concentration whilst the basal F-actin contents of the higher expressing T cell populations were elevated, suggesting constitutive activity of CCR4. Both sets of data were analysed using the mathematical models. RESULTS The affinity of CCL17 (also known as TARC) derived from analysis of the T cell data (pK(a) = 9.61 ± 0.17) was consistent with radioligand binding experiments (9.50 ± 0.11) while that from the [(35) S]GTPγS binding experiments was lower (8.27 ± 0.09). Its intrinsic efficacy differed between the two systems (110 in T cells vs. 11). CONCLUSIONS AND IMPLICATIONS The presence of constitutive receptor activity allows the absolute intrinsic efficacy of agonists to be determined without a contribution from the signal transduction system. Intrinsic efficacy estimated in this way is consistent with Furchgott's definition of this property. CCL17 may have a higher intrinsic efficacy at CCR4 in human T cells than that expressed recombinantly in CHO cells.

Genome-wide gene expression analysis suggests an important role of suppressed immunity in pathogenesis of Kashin-Beck disease

Objective

To investigate the differences between the gene expression profiles in peripheral blood mononuclear cells (PBMC) from normal controls and patients with Kashin-Beck disease (KBD).

Methods

Twenty KBD patients and 12 normal subjects were selected from a KBD-endemic area and divided into four pairs of KBD vs. control (KBD, n = 5 per pair; control, n = 3 per pair). RNAs were respectively isolated from KBD PBMCs and normal PBMCs. Gene expression profiles were analyzed by oligonucleotide microarray. The gene expression profiles in PBMCs from KBD patients and normal controls were compared and the differentially expressed genes were identified. The obtained microarray data was further confirmed by using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR).

Results

Approximately 501 genes, corresponding to 2.4% of the total probe transcripts, showed a 2-fold change in differential expression. 19.4% (97 out of 501)of the differentially expressed genes were commonly detected in all the four pairs. Among the 97 differentially expressed genes, 83 genes were up-regulated and 14 genes were down-regulated, compared with those in the normal controls. Some differentially expressed genes were found to be related to functions such as immunity, metabolism, apoptosis, cystoskeleton and cell movement, and extracellular matrix. The validity of our microarray data were supported by the results of qRT-PCR assay.

Conclusion

Differences in the PBMC gene expression profile between the KBD patients and the normal controls exhibited a similar pattern among all the four pairs of microarrays examined, indicating that the suppressed immunity may play an important role in the pathogenesis of KBD.

High-Content Analysis of CCR2 Antagonists on Human Primary Monocytes

The monocyte chemoattractant protein 1 (MCP-1)–driven activation of CC-type chemokine receptor 2 (CCR2) is one of the early key events to induce monocyte migration toward centers of inflammation. In this work, the authors analyzed MCP-1 internalization into primary human monocytes using partially automated liquid handling, automated fluorescence microscopic imaging, and a specific image analysis algorithm. A fluorophore-conjugated form of MCP-1 was rapidly endocytosed and retained by the monocytes. The CCR2 dependency of the MCP-1 internalization was demonstrated by the use of BMS CCR2 22, a CCR2-specific antagonist. The apparent inhibitory potencies of a series of small-molecule CCR2 antagonists were determined and compared in five assay formats, including the high-content analysis assay described in this work. Interestingly, some but not all antagonists showed markedly different inhibitory behaviors in the five readout systems, with an up to more than 100-fold difference between the highest and the lowest apparent inhibitory potencies. These findings raise the distinct possibility that some CCR2 antagonists are capable of discriminating between different functional states of the CCR2 receptor(s) and suggest strategies for the identification of functionally selective CCR2 antagonists with increased therapeutic advantage over nonselective antagonists.

Ccl22/MDC, is a prostaglandin dependent pyrogen, acting in the anterior hypothalamus to induce hyperthermia via activation of brown adipose tissue

CC Chemokine ligand 22 (Ccl22) is a selective, high affinity ligand at the CC chemokine receptor 4 (Ccr4). We have identified cDNAs encoding both ligand and receptor of the Ccl22-Ccr4 pair in cDNA libraries of the anterior hypothalamus/pre-optic area (AH/POA) by PCR. The AH/POA is the key brain region where endogenous pyrogens have been shown to act on warm sensitive neurons to affect thermogenesis in brown adipose tissue (BAT) and other thermogenically responsive tissues. We show that functional Ccr4 receptors are present in the AH/POA neurons as injection of Ccl22 into the POA but not to other hypothalamic nuclei induces an increase in core body temperature as measured by radiotelemetry. Indomethacin (5 mg/kg s.c) pre-treatment markedly reduced the hyperthermia evoked by POA injection of Ccl22 (10 ng/0.5 ul) and thus suggests that this hyperthermia is mediated through cyclooxygenase activation and thus likely through the formation and action of the pyrogen prostaglandin E2. The temperature elevation involves a decrease in the respiratory exchange ratio and increased activation of the brown adipose tissue as demonstrated by ¹⁸F-FDG-PET imaging. We describe a novel role to the ligand Ccl22 and its receptor Ccr4 in the anterior hypothalamus in temperature regulation that depends on the synthesis of the endogenous pyrogen, prostaglandin E2.

Regulatory T-cell trafficking: from thymic development to tumor-induced immune suppression

Regulatory T cells (Tregs) have become a priority for many investigators in immunology due to their potent immunosuppressive and tolerogenic effects. While Treg activity is required for normal immune homeostasis, dysregulation of their numbers can induce autoimmunity or aid in the pathogenesis of disease. Therefore, great effort has been made to understand the mechanisms by which Tregs accumulate in different areas of the body. Like other lymphocytes, Tregs migrate in response to a network of chemotactic stimuli involving chemokines, chemokine receptors, integrins, and their corresponding ligands. However, many of these stimuli are exclusive to Tregs, inducing their migration while leaving conventional populations unaffected. It is these selective stimuli that result in increased ratios of Tregs among conventional effector populations, leading to changes in immune suppression and homeostasis. This review explores selective Treg trafficking during thymic Treg development, migration to secondary lymphoid tissues and emigration into the periphery during homeostatic conditions, inflammation, and the tumor microenvironment, placing emphasis on stimuli that selectively recruits Tregs to target locations.

CCL5 as an adjuvant for cancer immunotherapy

IMPORTANCE OF THE FIELD

To date cancer immunotherapy has only achieved limited clinical efficacy, thus more efficient immunotherapeutic approaches need to be explored. The CC chemokine CCL5 plays a role in chemoattraction and activation of immune cells implying its potential clinical application as an adjuvant for boosting anti-tumor immunity, although an effect on carcinogenesis and tumor cell invasiveness is also reported to be associated with CCL5.

AREAS COVERED IN THIS REVIEW

Recent progress in exploiting CCL5 as an adjuvant for cancer prevention and treatment, and updated understanding on how CCL5 is involved in tumor invasiveness and carcinogenesis.

WHAT THE READER WILL GAIN

CCL5 represents a natural adjuvant for enhancing anti-tumor immune responses. However, animal experiments and clinical reports suggest that CCL5 plays a role in carcinogenesis and invasiveness of tumor cells. Therefore, a CCL5-based cancer therapeutic approach needs to avoid the CCL5-associated potential detrimental effects.

TAKE HOME MESSAGE

CCL5 has a pre-eminent role in chemotaxis and activation of a wide spectrum of immune cells. CCL5 functions as an adjuvant to boost anti-tumor immunity by diverse protocols such as co-immunization of recombinant CCL5 protein with tumor-associated antigen, vaccination with CCL-5-expressing tumor cells, or viral vector delivery of CCL5 cDNA into growing tumor. CCL5 may also promote tumor cell survival, proliferation and invasion by different mechanisms.

Role of platelets in neuroinflammation: a wide-angle perspective

OBJECTIVES

This review summarizes recent developments in platelet biology relevant to neuroinflammatory disorders. Multiple sclerosis (MS) is taken as the "Poster Child" of these disorders but the implications are wide. The role of platelets in inflammation is well appreciated in the cardiovascular and cancer research communities but appears to be relatively neglected in neurological research.

ORGANIZATION

After a brief introduction to platelets, topics covered include the matrix metalloproteinases, platelet chemokines, cytokines and growth factors, the recent finding of platelet PPAR receptors and Toll-like receptors, complement, bioactive lipids, and other agents/functions likely to be relevant in neuroinflammatory diseases. Each section cites literature linking the topic to areas of active research in MS or other disorders, including especially Alzheimer's disease.

CONCLUSION

The final section summarizes evidence of platelet involvement in MS. The general conclusion is that platelets may be key players in MS and related disorders, and warrant more attention in neurological research.

Chemokine (C-C motif) ligand 2 engages CCR2+ stromal cells of monocytic origin to promote breast cancer metastasis to lung and bone

Metastatic spread of cancer to distant vital organs, including lung and bone, is the overwhelming cause of breast cancer mortality and morbidity. Effective treatment of systemic metastasis relies on the identification and functional characterization of metastasis mediators to multiple organs. Overexpression of the chemokine (C-C motif) ligand 2 (CCL2) is frequently associated with advanced tumor stage and metastatic relapse in breast cancer. However, the functional mechanism of CCL2 in promoting organ-specific metastasis of breast cancer has not been rigorously investigated. Here, we used organ-specific metastatic sublines of the MDA-MB-231 human breast cancer cell line to demonstrate that overexpression of CCL2 promotes breast cancer metastasis to both lung and bone. Conversely, blocking CCL2 function with a neutralizing antibody reduced lung and bone metastases. The enhancement of lung and bone metastases by CCL2 was associated with increased macrophage infiltration and osteoclast differentiation, respectively. By performing functional assays with primary cells isolated from the wild type, CCL2 and CCR2 knock-out mice, we showed that tumor cell-derived CCL2 depends on its receptor CCR2 (chemokine, CC motif, receptor 2) expressed on stromal cells to exert its function in promoting macrophage recruitment and osteoclast differentiation. Overall, these data demonstrated that CCL2-expressing breast tumor cells engage CCR2(+) stromal cells of monocytic origin, including macrophages and preosteoclasts, to facilitate colonization in lung and bone. Therefore, CCL2 and CCR2 are promising therapeutic targets for simultaneously inhibiting lung and bone metastasis of breast cancer.

NK-dependent increases in CCL22 secretion selectively recruits regulatory T cells to the tumor microenvironment

Tumor-induced immune suppression involves the accumulation of immune-suppressive infiltrates in the microenvironment. This study demonstrates increased numbers of CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) in the lungs of C57BL/6 mice bearing a metastatic Lewis lung carcinoma (LLC) variant. These Tregs suppressed the proliferation of endogenous CD4(+)CD25(-) cells and expressed higher levels of the chemokine receptor CCR4 than other types of T cells. LLC-bearing lungs secreted elevated levels of the CCR4-associated chemokine CCL22 compared with normal lungs. However, CCL22 was not secreted by LLC or normal epithelial controls, suggesting that CCL22 is secreted by a nonepithelial component of the microenvironment. Migration assays revealed that medium conditioned by LLC-bearing lungs selectively recruited Tregs at higher frequencies than did medium conditioned by normal lungs. Neutralization of CCL22 significantly reduced this selective recruitment toward both conditioned media. A series of immunomagnetic isolations, FACS, and flow cytometric analyses were used to isolate different cellular fractions from both normal and LLC-bearing lungs. When isolated, only the NK-containing fractions secreted CCL22, and the same fraction isolated from LLC-bearing lungs secreted higher levels. Depletion of NK cells from both normal and LLC-bearing lung tissue significantly reduced CCL22 secretion, suggesting that a large portion of secreted CCL22 is NK cell dependent. Flow cytometric analysis of the lung NK compartments revealed no significant increase in NK cell numbers across LLC-bearing lung tissue as a whole as compared with normal tissue. However, immunofluorescent staining revealed an increased frequency of NK cells at the tumor periphery that were closely associated with the elevated FoxP3(+) infiltrate.

Distinct signatures of B-cell homeostatic and activation-dependent chemokine receptors in the development and progression of extragastric MALT lymphomas

Chemokine receptors mediate migration and activation of lymphocytes through binding of their ligands. Recent studies have revealed important contributions of chemokine receptors to the development, progression, and dissemination of haematopoietic neoplasms. Because the chemokine receptor expression profile in extragastric MALT lymphoma is unknown, we performed a comprehensive study on tissue samples of parotid glands, parotid glands affected by Sjögren syndrome, extragastric MALT lymphoma, and extranodal diffuse large B-cell lymphoma (eDLBCL) originating from MALT lymphoma (transformed MALT lymphoma). By investigating the expression of 19 chemokine receptors by real-time PCR using a semi-quantitative approach and of four chemokine receptors (CCR1, CCR5, CXCR6, and XCR1) by immunohistochemistry, we show that the chemokine receptor expression profiles of extragastric MALT lymphomas differ substantially from those of extranodal DBLCL, with lower expression of CCR1, CCR8, and CXCR3, and the absence of expression of CX3CR1 and XCR1 in eDLBCL. Expression of CCR6, CCR7, CXCR3, CXCR4, and CXCR5, responsible for B-cell homing to secondary lymphoid tissue, was detected in both B-cell malignancies. Expression of CCR4 was just detected in trisomy 3-positive MALT lymphoma cases. Comparing gastric with extragastric MALT lymphomas, up-regulation of CXCR1 and CXCR2 accompanied by down-regulation of CCR8 and CX3CR1 and loss of XCR1 expression in extragastric MALT lymphomas appear to be key determinants for the site of origin of MALT lymphomagenesis. Our results support a model of stepwise progression of extragastric MALT lymphoma from a non-neoplastic event to Sjögren syndrome, to MALT lymphoma, and finally to overt eDLBCL, guided by differentially expressed B-cell homeostatic and activation-dependent chemokine receptors and their ligands.

Detrimental role of CC chemokine receptor 4 in murine polymicrobial sepsis

CC chemokine receptor 4 (CCR4) and its two ligands, CCL17 and CCL22, are critically involved in different immune processes. In models of lipopolysaccharide-induced shock, CCR4-deficient (CCR4(-/-)) mice showed improved survival rates associated with attenuated proinflammatory cytokine release. Using CCR4(-/-) mice with a C57BL/6 background, this study describes for the first time the role of CCR4 in a murine model of polymicrobial abdominal sepsis, the colon ascendens stent peritonitis (CASP). CASP-induced sepsis led to a massive downregulation of CCR4 in lymphoid and nonlymphoid tissues, whereas the expression of CCL17 and CCL22 was independent of the presence of CCR4. After CASP, CCR4(-/-) animals showed a strongly enhanced bacterial clearance in several organs but not in the peritoneal lavage fluid and the blood. In addition, significantly reduced levels of proinflammatory cytokines/chemokines were measured in organ supernatants as well as in the sera of CCR4(-/-) mice. CCR4 deficiency consequently resulted in an attenuated severity of systemic sepsis and a strongly improved survival rate after CASP or CASP with intervention. Thus, our data provide clear evidence that CCR4 plays a strictly detrimental role in the course of polymicrobial sepsis.

Comparison of the potential multiple binding modes of bicyclam, monocylam, and noncyclam small-molecule CXC chemokine receptor 4 inhibitors

CXC chemokine receptor (CXCR)4 is an HIV coreceptor and a chemokine receptor that plays an important role in several physiological and pathological processes, including hematopoiesis, leukocyte homing and trafficking, metastasis, and angiogenesis. This receptor belongs to the class A family of G protein-coupled receptors and is a validated target for the development of a new class of antiretroviral therapeutics. This study compares the interactions of three structurally diverse small-molecule CXCR4 inhibitors with the receptor and is the first report of the molecular interactions of the nonmacrocyclic CXCR4 inhibitor (S)-N'-(1H-benzimidazol-2-ylmethyl)-N'-(5,6,7,8-tetrahydroquinolin-8-yl)butene-1,4-diamine (AMD11070). Fourteen CXCR4 single-site mutants representing amino acid residues that span the entire putative ligand binding pocket were used in this study. These mutants were used in binding studies to examine how each single-site mutation affected the ability of the inhibitors to compete with (125)I-stromal-derived factor-1alpha binding. Our data suggest that these CXCR4 inhibitors bind to overlapping but not identical amino acid residues in the transmembrane regions of the receptor. In addition, our results identified amino acid residues that are involved in unique interactions with two of the CXCR4 inhibitors studied. These data suggest an extended binding pocket in the transmembrane regions close to the second extracellular loop of the receptor. Based on site-directed mutagenesis and molecular modeling, several potential binding modes were proposed for each inhibitor. These mechanistic studies might prove to be useful for the development of future generations of CXCR4 inhibitors with improved clinical pharmacology and safety profiles.

Using guinea pigs in studies relevant to asthma and COPD

The guinea pig has been the most commonly used small animal species in preclinical studies related to asthma and COPD. The primary advantages of the guinea pig are the similar potencies and efficacies of agonists and antagonists in human and guinea pig airways and the many similarities in physiological processes, especially airway autonomic control and the response to allergen. The primary disadvantages to using guinea pigs are the lack of transgenic methods, limited numbers of guinea pig strains for comparative studies and a prominent axon reflex that is unlikely to be present in human airways. These attributes and various models developed in guinea pigs are discussed.

Two C-terminal peptides of human CKLF1 interact with the chemokine receptor CCR4

Human chemokine-like factor 1 (CKLF1) exhibits chemotactic effects on leukocytes. A previous study demonstrated that CKLF1 is a functional ligand for human CC chemokine receptor 4 (CCR4). In this study, N-terminal amino acid sequencing of secreted CKLF1 protein showed that it contains at least two peptides, C27 and C19. To examine whether C27 or C19 play a role via CCR4, C27 and C19 were chemically synthesized and analyzed by chemotaxis, calcium mobilization, and receptor internalization assays in CCR4-tranfected HEK293 cells or Hut78 cells. The chemotaxis assay showed that C27 could induce chemotaxis to CCR4-transfected HEK293 cells or Hut78 cells while C19 had weaker chemotactic activity, especially in Hut78 cells. C27- or C19-induced chemotaxis was abolished by pertussis toxin, suggesting the involvement of a Gi/o pathway. C27- or C19-induced chemotaxis was also inhibited by an antagonist of CCR4 that show good binding potency, excellent chemotaxis inhibitory activity and selectivity toward CCR4, suggesting that their chemotactic activity specifically involved CCR4. The chemotactic response of CCR4-tranfected HEK293 cells to C27 or C19 was markedly inhibited by preincubation with TARC/CCL17. TARC/CCL17 effectively desensitized the calcium mobilization induced by C27 or C19. Similarly, both of C27 or C19 also desensitized the calcium mobilization and chemotaxis of CCR4-tranfected HEK293 cells in response to TARC/CCL17, suggesting that they might interact with a common receptor. Both C27- and C19-induced clear internalization of CCR4-EGFP. These results confirm that the secreted peptides of CKLF1, C27 and C19, have functional activation via CCR4.

Chemical interactions between fibrosarcoma cancer cells and sensory neurons contribute to cancer pain

In an experimental model of cancer pain, the hyperalgesia that occurs with osteolytic tumor growth is associated with the sensitization of nociceptors. We examined functional and molecular changes in small-diameter dorsal root ganglion (DRG) neurons to determine cellular mechanisms underlying this sensitization. The occurrence of a Ca2+ transient in response to either KCl (25 mM) or capsaicin (500 nM) increased in small neurons isolated from murine L3-L6 DRGs ipsilateral to fibrosarcoma cell tumors. The increased responses were associated with increased mRNA levels for the Ca2+ channel subunit alpha2delta1 and TRPV1 receptor. Pretreatment with gabapentin, an inhibitor of the alpha2delta1 subunit, blocked the increased response to KCl in vitro and the mechanical hyperalgesia in tumor-bearing mice in vivo. Similar increases in neuronal responsiveness occurred when DRG neurons from naive mice and fibrosarcoma cells were cocultured for 48 h. The CC chemokine ligand 2 (CCL2) may contribute to the tumor cell-induced sensitization because CCL2 immunoreactivity was present in tumors, high levels of CCL2 peptide were present in microperfusates from tumors, and treatment of DRG neurons in vitro with CCL2 increased the amount of mRNA for the alpha2delta1 subunit. Together, our data provide strong evidence that the chemical mediator CCL2 is released from tumor cells and evokes phenotypic changes in sensory neurons, including increases in voltage-gated Ca2+ channels that likely underlie the mechanical hyperalgesia in the fibrosarcoma cancer model. More broadly, this study provides a novel in vitro model to resolve the cellular and molecular mechanisms by which tumor cells drive functional changes in nociceptors.

Tumor-Derived Chemokine MCP-1/CCL2 Is Sufficient for Mediating Tumor Tropism of Adoptively Transferred T Cells

To exert a therapeutic effect, adoptively transferred tumor-specific CTLs must traffic to sites of tumor burden, exit the circulation, and infiltrate the tumor microenvironment. In this study, we examine the ability of adoptively transferred human CTL to traffic to tumors with disparate chemokine secretion profiles independent of tumor Ag recognition. Using a combination of in vivo tumor tropism studies and in vitro biophotonic chemotaxis assays, we observed that cell lines derived from glioma, medulloblastoma, and renal cell carcinoma efficiently chemoattracted ex vivo-expanded primary human T cells. We compared the chemokines secreted by tumor cell lines with high chemotactic activity with those that failed to elicit T cell chemotaxis (Daudi lymphoma, 10HTB neuroblastoma, and A2058 melanoma cells) and found a correlation between tumor-derived production of MCP-1/CCL2 (> or =10 ng/ml) and T cell chemotaxis. Chemokine immunodepletion studies confirmed that tumor-derived MCP-1 elicits effector T cell chemotaxis. Moreover, MCP-1 is sufficient for in vivo T cell tumor tropism as evidenced by the selective accumulation of i.v. administered firefly luciferase-expressing T cells in intracerebral xenografts of tumor transfectants secreting MCP-1. These studies suggest that the capacity of adoptively transferred T cells to home to tumors may be, in part, dictated by the species and amounts of tumor-derived chemokines, in particular MCP-1.

Leishmania infection impairs beta 1-integrin function and chemokine receptor expression in mononuclear phagocytes

Leishmania spp. are intracellular parasites that cause lesions in the skin, mucosa, and viscera. We have previously shown that Leishmania infection reduces mononuclear phagocyte adhesion to inflamed connective tissue. In this study, we examined the role of adhesion molecules and chemokines in this process. Infection rate (r = -0.826, P = 0.003) and parasite burden (r = -0.917, P = 0.028) negatively correlated to mouse phagocyte adhesion. The decrease (58.7 to 75.0% inhibition, P = 0.005) in phagocyte adhesion to connective tissue, induced by Leishmania, occurred as early as 2 h after infection and was maintained for at least 24 h. Interestingly, impairment of cell adhesion was sustained by phagocyte infection, since it was not observed following phagocytosis of killed parasites (cell adhesion varied from 15.2% below to 24.0% above control levels, P > 0.05). In addition, Leishmania infection diminished cell adhesion to fibronectin (54.1 to 96.2%, P < 0.01), collagen (15.7 to 83.7%, P < 0.05), and laminin (59.1 to 82.2%, P < 0.05). The CD11b(hi) subpopulation was highly infected (49.6 to 97.3%). Calcium and Mg(2+) replacement by Mn(2+), a treatment that is known to induce integrins to a high state of affinity for their receptors, reverted the inhibition in adhesion caused by Leishmania. This reversion was completely blocked by anti-VLA4 antibodies. Furthermore, expression of CCR4 and CCR5, two chemokine receptors implicated in cell adhesion, was found to be downregulated 16 h after infection (2.8 to 4.1 times and 1.9 to 2.8 times, respectively). Together, these results suggest that mechanisms regulating integrin function are implicated in the change of macrophage adhesion in leishmaniasis.

Induction of chemokines and chemokine receptors CCR2b and CCR4 in authentic human osteoclasts differentiated with RANKL and osteoclast like cells differentiated by MCP-1 and RANTES

Chemokines MCP-1 and RANTES are induced when authentic bone resorbing human osteoclasts differentiate from monocyte precursors in vitro. In addition, MCP-1 and RANTES can stimulate the differentiation of cells with the visual appearance of osteoclasts, being multinuclear and positive for tartrate resistance acid phosphatase (TRAP +). We show here that MIP1alpha is also potently induced by RANKL during human osteoclast differentiation and that this chemokine also induces the formation of TRAP + multinucleated cells in the absence of RANKL. MIP1alpha was able to overcome the potent inhibition of GM-CSF on osteoclast differentiation, permitting the cells to pass through to TRAP + multinuclear cells, however these were unable to form resorption pits. Chemokine receptors CCR2b and CCR4 were potently induced by RANKL (12.6- and 49-fold, P = 4.0 x 10(-7) and 4.0 x 10(-8), respectively), while CCR1 and CCR5 were not regulated. Chemokine treatment in the absence of RANKL also induced MCP-1, RANTES and MIP1alpha. Unexpectedly, treatment with MCP-1 in the absence of RANKL resulted in 458-fold induction of CCR4 (P = 1.0 x 10(-10)), while RANTES treatment resulted in twofold repression (P = 1.0 x 10(-4)). Since CCR2b and CCR4 are MCP-1 receptors, these data support the existence of an MCP-1 autocrine loop in human osteoclasts differentiated using RANKL.

Migration of cytotoxic T lymphocytes toward melanoma cells in three-dimensional organotypic culture is dependent on CCL2 and CCR4

Studies in experimental animal models have demonstrated that chemokines produced by tumor cells attract chemokine receptor-positive T lymphocytes into the tumor area. However, in cancer patients, the role of chemokines in T lymphocyte trafficking toward human tumor cells is relatively unexplored. In the present study, the migration of a melanoma patient's CTL toward autologous tumor cells has been studied in a novel three-dimensional organotypic melanoma culture. In this model, CTL migrated toward tumor cells, resulting in tumor cell apoptosis. CTL migration was mediated by the CC chemokine receptor (CCR)4 expressed by the CTL and the CC chemokine ligand (CCL)2 secreted by the tumor cells, as evidenced by blockage of CTL migration by CCL2 or antibodies to CCL2 or CCR4. These results were confirmed in a Transwell migration assay in which the CTL actively migrated toward isolated CCL2 and migration was inhibited by anti-CCR4 antibody. These studies, together with previous studies in mice indicating regression of CCL2-transduced tumor cells, suggest that CCL2 may be useful as an immunotherapeutic agent for cancer patients.

Chemokine-like factor 1 is a functional ligand for CC chemokine receptor 4 (CCR4)

Chemokine-like factor 1 (CKLF1) exhibits chemotactic effects on leukocytes. Its amino acid sequence shares similarity with those of TARC/CCL17 and MDC/CCL22, the cognate ligands for CCR4. The chemotactic effects of CKLF1 for CCR4-transfected cells could be desensitized by TARC/CCL17 and markedly inhibited by PTX. CKLF1 induced a calcium flux in CCR4-transfected cells and fully desensitized a subsequent response to TARC/CCL17, and TARC/CCL17 could partly desensitize the response to CKLF1. CKLF1 caused significant receptor internalization in pCCR4-EGFP transfected cells. Taken together, CKLF1 is a novel functional ligand for CCR4.

Enhanced Natural Killer Cell Binding and Activation by Low-Fucose IgG1 Antibody Results in Potent Antibody-Dependent Cellular Cytotoxicity Induction at Lower Antigen Density

PURPOSE

Recent studies have revealed that fucose removal from the oligosaccharides of human IgG1 antibodies results in a significant enhancement of antibody-dependent cellular cytotoxicity (ADCC) via improved IgG1 binding to FcgammaRIIIa. In this report, we investigated the relationship between enhanced ADCC and antigen density on target cells using IgG1 antibodies with reduced fucose.

EXPERIMENTAL DESIGN

Using EL4 cell-derived transfectants with differential expression levels of exogenous human CC chemokine receptor 4 or human CD20 as target cells, ADCC of fucose variants of chimeric IgG1 antibodies specific for these antigens were measured. We further investigated IgG1 binding to natural killer (NK) cells and NK cell activation during ADCC induction to elucidate the mechanism by which low-fucose IgG1 induces ADCC upon target cells with low antigen expression.

RESULTS

Low-fucose IgG1s showed potent ADCC at low antigen densities at which their corresponding high-fucose counterparts could not induce measurable ADCC. The quantitative analysis revealed that fucose depletion could reduce the antigen amount on target cells required for constant degrees of ADCC induction by 10-fold for CC chemokine receptor 4 and 3-fold for CD20. IgG1 binding to NK cells was increased by ligating IgG1 with clustered antigen, especially for low-fucose IgG1. Up-regulation of an activation marker, CD69, on NK cells, particularly the CD56(dim) subset, in the presence of both the antibody and target cells was much greater for the low-fucose antibodies.

CONCLUSIONS

Our data showed that fucose removal from IgG1 could reduce the antigen amount required for ADCC induction via efficient recruitment and activation of NK cells.