CC chemokines and their receptors play a fundamental role in trafficking and activation of leukocytes at sites of inflammation, contributing to joint damage in rheumatoid arthritis. Met-RANTES, an amino-terminal–modified methionylated form of RANTES (CCL5), antagonizes the binding of the chemokines RANTES and macrophage inflammatory protein 1α (MIP-1α; CCL3) to their receptors CCR1 and CCR5, respectively. The aim of this study was to investigate whether Met-RANTES could ameliorate adjuvant-induced arthritis (AIA) in the rat.
Using immunohistochemistry, enzyme-linked immunosorbent assay, real-time reverse transcription–polymerase chain reaction, Western blot analysis, adoptive transfer, and chemotaxis, we defined joint inflammation, bony destruction, neutrophil and macrophage migration, Met-RANTES binding affinity to rat receptors, proinflammatory cytokine and bone marker levels, CCR1 and CCR5 expression and activation, and macrophage homing into joints with AIA.
Administration of Met-RANTES as a preventative reduced the severity of joint inflammation. Administration of Met-RANTES to ankles with AIA showed decreases in inflammation, radiographic soft tissue swelling, and bone erosion. Met-RANTES significantly reduced the number of neutrophils and macrophages at the peak of arthritis compared with saline-injected controls. Competitive chemotaxis in peripheral blood mononuclear cells demonstrated that Met-RANTES inhibited MIP-1α and MIP-1β at 50% inhibition concentrations of 5 nM and 2 nM, respectively. Furthermore, levels of tumor necrosis factor α, interleukin-1β, macrophage colony-stimulating factor, and RANKL were decreased in joints with AIA in the Met-RANTES group compared with the control group. Interestingly, the expression and activation of CCR1 and CCR5 in the joint were down-regulated in the Met-RANTES group compared with the control group. Functionally, Met-RANTES administration decreased adoptively transferred peritoneal macrophage homing into the joint.
The data suggest that the targeting of Th1-associated chemokine receptors reduce joint inflammation, bone destruction, and cell recruitment into joints with AIA.
Chagas’ disease is caused by Trypanosoma cruzi infection and is characterized by chronic fibrogenic inflammation and heart dysfunction. Chemokines are produced during infection and drive tissue inflammation. In rats, acute infection is characterized by intense myocarditis and regression of inflammation after control of parasitism. We investigated the role of CCL3 and CCL5 during infection by using DNA vaccination encoding for each chemokine separately or simultaneously. MetRANTES treatment was used to evaluate the role of CCR1 and CCR5, the receptors for CCL3 and CCL5. Vaccination with CCL3 or CCL5 increased heart parasitism and decreased local IFN-γ production, but did not influence intensity of inflammation. Simultaneous treatment with both plasmids or treatment with MetRANTES enhanced cardiac inflammation, fibrosis and parasitism. In conclusion, chemokines CCL3 and CCL5 are relevant, but not essential, for control of T. cruzi infection in rats. On the other hand, combined blockade of these chemokines or their receptors enhanced tissue inflammation and fibrosis, clearly contrasting with available data in murine models of T. cruzi infection. These data reinforce the important role of chemokines during T. cruzi infection but suggest that caution must be taken when expanding the therapeutic modulation of the chemokine system in mice to the human infection.
Chemokines; CCR5; Trypanosoma cruzi; Myocarditis
CCR5 and its ligands (CCL3, CCL4 and CCL5) may play a role in inflammatory cell recruitment into the joint. However, recently it has been reported that CCR5 on T cells and neutrophils acts as a decoy receptor for CCL3 and CCL5 to assist in resolution of inflammation. To determine whether CCR5 functions as a pro-inflammatory or anti-inflammatory mediator in arthritis, we examined the role of CCR5 in proteoglycan (PG)-induced arthritis (PGIA).
PGIA was induced by immunization of BALB/c wild type (WT) and CCR5-deficient (CCR5−/−) mice with human PG in adjuvant. The onset and severity were monitored overtime. Met-RANTES was used to block CCR5 in vivo. Arthritis was transferred to SCID mice with spleen cells from arthritis WT and CCR5−/− mice. Cytokines and chemokines were measured by ELISA.
Treatment with the CCR5 inhibitor, Met-RANTES, and CCR5−/− mice developed exacerbated arthritis late in the course of disease. The increase in arthritis severity in CCR5−/− correlated with elevated serum levels of CCL5. However, exacerbated arthritis was not intrinsic to the CCR5−/− lymphoid cells as arthritis transferred into SCID recipients was similar in WT and CCR5−/− mice. CCR5 expression in the SCID was sufficient to clear CCL5 as serum levels of CCL5 were the same in SCID recipients receiving WT or CCR5−/− cells.
These data demonstrate that CCR5 is a key player in controlling the resolution of inflammation in experimental arthritis.
Autoimmunity; Inflammation; Rheumatoid Arthritis; Chemokine and Rodent
Chemokines are likely to play important roles in the pathophysiology of diseases associated with Epstein-Barr virus (EBV). Here, we have analyzed the repertoire of chemokines expressed by EBV-infected B cells. EBV infection of B cells induced expression of TARC/CCL17 and MDC/CCL22, which are known to attract Th2 cells and regulatory T cells via CCR4, and also upregulated constitutive expression of MIP-1α/CCL3, MIP-1β/CCL4, and RANTES/CCL5, which are known to attract Th1 cells and cytotoxic T cells via CCR5. Accordingly, EBV-immortalized B cells secreted these chemokines, especially CCL3, CCL4, and CCL22, in large quantities. EBV infection or stable expression of LMP1 also induced CCL17 and CCL22 in a B-cell line, BJAB. The inhibitors of the TRAF/NF-κB pathway (BAY11-7082) and the p38/ATF2 pathway (SB202190) selectively suppressed the expression of CCL17 and CCL22 in EBV-immortalized B cells and BJAB-LMP1. Consistently, transient-transfection assays using CCL22 promoter-reporter constructs demonstrated that two NF-κB sites and a single AP-1 site were involved in the activation of the CCL22 promoter by LMP1. Finally, serum CCL22 levels were significantly elevated in infectious mononucleosis. Collectively, LMP1 induces CCL17 and CCL22 in EBV-infected B cells via activation of NF-κB and probably ATF2. Production of CCL17 and CCL22, which attract Th2 and regulatory T cells, may help EBV-infected B cells evade immune surveillance by Th1 cells. However, the concomitant production of CCL3, CCL4, and CCL5 by EBV-infected B cells may eventually attract Th1 cells and cytotoxic T cells, leading to elimination of EBV-infected B cells at latency III and to selection of those with limited expression of latent genes.
beta-Chemokines and their receptors mediate the trafficking and activation of a variety of leukocytes including the lymphocyte and macrophage. An array of no less than eight beta-chemokine receptors has been identified, four of which are capable of recognizing the chemokines MIP1alpha and RANTES. Genetic deletion of one of the MIP1alpha and RANTES receptors, CCR5, is associated with protection from infection with HIV-1 in humans, while deletion of the ligand MIP1alpha protects against Coxsackie virus-associated myocarditis. In this report we show that the deletion of another receptor for MIP1alpha and RANTES, the CCR1 receptor, is associated with protection from pulmonary inflammation secondary to acute pancreatitis in the mouse. The protection from lung injury is associated with decreased levels of TNF-alpha in a temporal sequence indicating that the activation of the CCR1 receptor is an early event in the systemic inflammatory response syndrome.
CD4+ T cells are critical for effective immune responses against HIV, but they are also the main cell type targeted by the virus. To investigate the key factors that could protect these cells from infection, we evaluated the capacity of HIV gp120-specific human CD4+ T cells to produce chemokines that inhibit HIV and determined their contribution in suppressing infection in the cells. Antigen stimulation of the CD4+ T cells elicited production of high amounts of CCR5 chemokines MIP-1α (CCL3), MIP-1β (CCL4), and RANTES (CCL5). Production of these CCR5 ligands was more readily and reproducibly detected than that of IFN-γ or IL-2. Importantly, in association with secretion of the CCR5 ligands, antigen stimulation made these CD4+ T cells more resistant to CCR5-tropic HIV-1. Conversely, in the absence of antigen stimulation, the cells were readily infected by the virus, and after infection, their capacity to produce MIP-1β and IFN-γ rapidly declined. Thus, vaccines that trigger HIV-specific CD4+ T cells to elicit robust and rapid production of anti-viral chemokines would be advantageous. Such responses would protect virus-specific CD4+ T cells from HIV infection and preserve their critical functions in mounting and maintaining long-lasting immunity against the virus.
The underlying inflammation present in chronic airway diseases is orchestrated by increased expression of CC chemokines that selectively recruit leukocyte populations into the pulmonary system. Human CCL26 signals through CC chemokine receptor 3 (CCR3), is dramatically upregulated in challenged asthmatics, and stimulates recruitment of eosinophils (EOSs) and other leukocytes. CCL26 participates in regulation of its receptor CCR3 and modulates expression of a variety of chemokines in alveolar type II cells. Utilizing the A549 alveolar type II epithelial cell culture model, we carried out studies to test the hypothesis that CCL26-siRNA treatment of these cells would ameliorate Th2-driven release of the eotaxins and other CCR3 ligands that would, in turn, decrease recruitment and activation of EOSs. Results demonstrate that CCL26-siRNA treatments decreased interleukin-4-induced CCL26 and CCL24 expression by >70%. CCL26-directed small-interfering RNA (siRNA) treatments significantly decreased release of CCL5 (RANTES), CCL15 (MIP-1δ), CCL8 (MCP-2), and CCL13 (MCP-4). In bioactivity assays it was shown that EOS migration and activation were reduced up to 80% and 90%, respectively, when exposed to supernatants of CCL26-siRNA-treated cells. These results provide evidence that CCL26 may be an appropriate target for development of new therapeutic agents designed to alleviate the underlying inflammation associated with chronic diseases of the airways.
Helicobacter pylori infection is associated with an inflammatory response in the gastric mucosa, leading to chronic gastritis, peptic ulcers, and gastric cancer. There is increased T-cell infiltration at the site of infection with H. pylori. CCR6, a specific β-chemokine receptor for CCL20 (MIP-3α/LARC/exodus), has recently been reported to mediate lymphocyte homeostasis and immune responses in mucosal tissue, and it may play a role in chemokine-mediated lymphocyte trafficking during gastric inflammation. In this study, we investigated the role of CCR6 and its ligand, CCL20, in inducing an inflammatory response in the gastric mucosa during H. pylori infection. Gastric infiltrating T lymphocytes were isolated from endoscopic biopsy specimens of H. pylori gastritis patients and analyzed for the expression of the CCR6 chemokine receptor. Our results demonstrated that there was significantly increased CCR6 expression in CD3+ T cells infiltrating the gastric mucosa, and the CCR6 ligand, the CCL20 chemokine, was selectively expressed in inflamed gastric tissues. The production of CCL20 was upregulated in response to H. pylori in gastric epithelial cells when there was stimulation by the proinflammatory cytokines interleukin-1β and tumor necrosis factor alpha. Furthermore, recombinant CCL20 induced lymphocyte chemotaxis migration in fresh gastric T cells ex vivo, indicating that the gastric T cells could migrate toward inflammatory sites via CCR6/CCL20 interaction. Our results suggest that the interaction between CCL20 and CCR6 may play a role in chemokine-mediated lymphocyte trafficking during gastric inflammation in Helicobacter infection.
Importance of the field
Psoriasis is a common, chronic autoimmune disease of the skin. Despite a number of effective treatments, new therapies are needed with enhanced efficacy, safety, and convenience. Chemokine receptors are G protein-coupled receptors that control leukocyte trafficking, and like other G protein-coupled receptors, are good potential drug targets. The chemokine receptor CCR6 is expressed on the Th17 subset of CD4+ T cells, which produces IL-17A/F, IL-22, TNF-α and other cytokines, and which has been implicated in the pathogenesis of psoriasis. CCR6 and its ligand, CCL20/MIP-3α, are highly expressed in psoriatic skin and CCR6 is necessary for the pathology induced in a mouse model of psoriasis-like inflammation.
Areas covered in this review
This review will summarize the evidence for the importance of the IL-23/Th17 axis, and in particular CCR6 and CCL20 in psoriasis, dating from 2000 to the present, and discuss the possibility of inhibiting CCR6 as treatment for the disease.
What the reader will gain
The review will inform the reader of the current thinking on the mechanisms of inflammation in psoriasis and the possible roles for CCR6 (and CCL20) in disease pathogenesis.
Take home message
We conclude that CCR6 should be investigated as a potential therapeutic target in psoriasis.
Psoriasis; Chemokines; Inflammation; Autoimmune disease
Chronic inflammation containing CD8+ lymphocytes, neutrophils, and macrophages, and pulmonary emphysema coexist in lungs from patients with chronic obstructive pulmonary disease. Although this inflammatory response is believed to cause the remodeling that is seen in these tissues, the mechanism(s) by which inflammation causes emphysema have not been defined. Here we demonstrate that interferon γ (IFN-γ), a prominent product of CD8+ cells, causes emphysema with alveolar enlargement, enhanced lung volumes, enhanced pulmonary compliance, and macrophage- and neutrophil-rich inflammation when inducibly targeted, in a transgenic fashion, to the adult murine lung. Prominent protease and antiprotease alterations were also noted in these mice. They included the induction and activation of matrix metalloproteinase (MMP)-12 and cathepsins B, H, D, S, and L, the elaboration of MMP-9, and the selective inhibition of secretory leukocyte proteinase inhibitor. IFN-γ causes emphysema and alterations in pulmonary protease/antiprotease balance when expressed in pulmonary tissues.
chronic obstructive pulmonary disease; matrix metalloproteinase; cathepsin; neutrophil; secretory leukocyte proteinase inhibitor
Trafficking and inflammation in airway diseases are, in part, modulated by members of the CC chemokine family, eotaxin-1 (CCL11), eotaxin-2 (CCL24), and eotaxin-3 (CCL26), which transduce signals through their CCR3 receptor. In this context, we hypothesized that transfecting alveolar type II epithelial cells with CCR3-targeted siRNA or antisense (AS-ODN) sequences will downregulate cellular synthesis and release of the primary CCR3 ligands CCL26 and CCL24 and will modulate other CCR3 ligands. The human A549 alveolar type II epithelium-like cell culture model was used for transfection and subsequent effects on CCR3 agonists. siRNAs were particularly effective. PCR showed a 60-80% decrease in mRNA and immunoblots showed up to 75-84% reduction of CCR3 in siRNA treated cells. CCR3-siRNA treatments reduced IL-4 stimulated CCL26 release and constitutive CCL24 release by 65% and 80%, respectively. Release of four additional CCR3 agonists RANTES, MCP-2, MCP-3 and MCP-4 was also significantly reduced by CCR3-siRNA treatments of the alveolar type II cells. Activation of eosinophils, assessed as superoxide anion generation, was reduced when eosinophils were treated with supernatants of A549 cells pretreated with CCR3-targeted siRNAs or AS-ODNs. Collectively, the data suggest that post-transcriptional regulation of CCR3 receptors may be a potential therapeutic approach for interrupting proinflammatory signaling.
alveolar type II cells; CCR3 receptor; eotaxins; siRNA; antisense oligonucleotides
Dengue virus (DENV), a mosquito-borne flavivirus, is a public health problem in many tropical countries. Recent clinical data have shown an association between levels of different chemokines in plasma and severity of dengue. We evaluated the role of CC chemokine receptors CCR1, CCR2 and CCR4 in an experimental model of DENV-2 infection in mice. Infection of mice induced evident clinical disease and tissue damage, including thrombocytopenia, hemoconcentration, lymphopenia, increased levels of transaminases and pro-inflammatory cytokines, and lethality in WT mice. Importantly, infected WT mice presented increased levels of chemokines CCL2/JE, CCL3/MIP-1α and CCL5/RANTES in spleen and liver. CCR1-/- mice had a mild phenotype with disease presentation and lethality similar to those of WT mice. In CCR2-/- mice, lethality, liver damage, levels of IL-6 and IFN-γ, and leukocyte activation were attenuated. However, thrombocytopenia, hemoconcentration and systemic TNF-α levels were similar to infected WT mice. Infection enhanced levels of CCL17/TARC, a CCR4 ligand. In CCR4-/- mice, lethality, tissue injury and systemic inflammation were markedly decreased. Despite differences in disease presentation in CCR-deficient mice, there was no significant difference in viral load. In conclusion, activation of chemokine receptors has discrete roles in the pathogenesis of dengue infection. These studies suggest that the chemokine storm that follows severe primary dengue infection associates mostly to development of disease rather than protection.
Chemokines immobilized on endothelial cells play a central role in the induced firm adhesion and transendothelial migration of leukocytes. Activation of platelets at sites of vascular injury is considered to support leukocyte adhesion and extravasation. However, activated platelets also secrete soluble glycosaminoglycans that can interfere with immobilization of chemokines. We therefore analyzed the impact of platelet derived glycosaminoglycans on the immobilization of the chemokine CCL5 (RANTES) on human microvascular endothelial cells and their influence on CCL5-CCR5 interactions.
We confirm that undiluted serum in contrast to plasma decreases binding of CCL5 to endothelial cells. However, when lower concentrations of serum were used, CCL5-presentation on endothelial cells was markedly enhanced. This enhancement was neutralized if serum was digested with chondroinitase ABC. Using different chondroitinsulfate-subtypes we demonstrate that chondroitinsulfate A mediates the enhanced presentation of CCL5 on endothelial cells, whereas chondroitinsulfate B/C even at low concentrations block CCL5 binding. CCR5 downregulation on CCR5-transfected CHO cells or human monocytes is increased by preincubation of CCL5 with serum or chondroitinsulfate A.
We show that chondroitinsulfate A released from platelets increases the binding of chemokines to endothelial cells and supports receptor internalization in a dose dependent manner. These data help to understand the proinflammatory effects of activated platelets.
Several CC-motif chemokine ligands (CCLs) can block HIV-1 binding sites on CC-motif chemokine receptor 5 (CCR5) and inhibit viral entry. We studied single nucleotide polymorphisms (SNPs) in genes encoding three CCR5 ligands [CCL3 (MIP-1α), CCL4 (MIP-1β), and CCL5 (RANTES)] along with an adjacent gene encoding a CCR2 ligand [CCL2 (MCP-1)] to identify candidate markers for HIV-1 infection and pathogenesis. Analyses of 567 HIV-1 serodiscordant Zambian couples revealed that rs5029410C (in CCL3 intron 2) was associated with lower viral load (VL) in seroconverters, adjusted for gender and age (regression β=−0.57 log10, P=4×10−6). In addition, rs34171309A in CCL3 exon 3 was associated with increased risk of HIV-1 acquisition in exposed seronegatives (hazard ratio=1.52, P=0.006 when adjusted for donor VL and genital ulcer/inflammation). The CCL3 exon 3 SNP, encoding a conservative Glu-to-Asp substitution, and five neighboring SNPs in tight linkage disequilibrium all showed similar associations with HIV-1 acquisition. How these multiple CCL3 SNPs may alter the occurrence or course of HIV-1 infection remains to be determined.
HIV-1 transmission; CCL2; CCL3; CCL4; CCL5; SNP
Chemokines are a superfamily of chemotactic cytokines that play an important role in leukocyte trafficking and have been implicated as functional mediators of immunopathology in experimental autoimmune encephalomyelitis (EAE). In the present study, we investigated the role of the CCL20 receptor, CCR6, in chronic EAE. After immunization with myelin oligodendrocyte glycoprotein 35–55 in CFA, CCR6-/- mice developed a significantly more severe chronic EAE as compared to wild type immunized animals. CCR6 expression was not required by T cells to induce EAE. Measurement of peripheral T cell responses showed differences in IFN-γ and IL-17 responses between CCR6-/- and wild type mice. At the time when CCR6-/- mice showed significantly more severe chronic EAE there was a significant decrease in PD-L1-expressing mDC in the spleens and no differences in Foxp3 Treg. Furthermore, add back of mDC with increased PD-L1 expression to CCR6-/- mice reduced the severe chronic EAE disease phase to that of wild type controls. The results suggest a role for CCR6-expressing PD-L1+ mDC in regulating EAE progression.
multiple sclerosis; chemokine; CCL20; CCR6; EAE; central nervous system
The CC chemokine receptor 4 (CCR4) shows selectivity for the recruitment of memory T cell subsets, including those of the T helper cell type 2 (Th2) phenotype. In humans, CCR4+ T cells are recruited to the asthmatic lung in response to allergen challenge; however, the contribution of this pathway to allergic disease remains uncertain. We therefore investigated the role of CCR4 in allergic airways inflammation in the guinea pig. Blockade of CCR4 with a specific antibody resulted in only minor changes in numbers of CCR4+ Th cells in the bronchoalveolar lavage fluid of allergen-challenged guinea pigs and failed to inhibit the generation of eotaxin/CC chemokine ligand (CCL)11 or macrophage-derived chemokine/CCL22 or the recruitment of inflammatory leukocytes to the lung. These data suggest that although CCR4 was originally proposed as a marker of Th2 status, antigen-specific Th2 cells are recruited to the lung predominantly by other pathways. This study casts doubts on the validity of CCR4 as a therapeutic target in the treatment of asthma.
T lymphocytes; chemokines; allergy
Chemokines and chemokine receptors play a role in migration of circulating leukocytes to the region of inflammation. Human LZIP is an uncharacterized transcription factor and is known to participate in leukotactin (Lkn)-1/CCL15-induced cell migration. We investigated the role of human LZIP in expression of CC chemokine receptors (CCRs) and its involvement in monocyte migration. RNase protection analysis showed that LZIP increased mRNA expression of CCR2 and CCR1 in THP-1 cells. Surface expressions of both CCR2 and CCR1 were also increased by LZIP. Results from an electrophoretic mobility shift assay showed that LZIP binds to the C/EBP element in the CCR2 promoter. LZIP also enhanced the chemotactic activities of monocyte chemoattractant protein-1/CCL2 and Lkn-1. These results suggest that LZIP regulates expression of chemokine receptors that are involved in monocyte migration.
chemokines; chemotaxis; inflammation; monocytes; receptors, chemokine; transcription factors
CCR7 is a chemokine receptor expressed on the surfaces of T cells, B cells, and mature dendritic cells that controls cell migration in response to the cognate ligands CCL19 and CCL21. CCR7 is critical for the generation of an adaptive T cell response. However, the roles of CCR7 in the host defense against pulmonary infection and innate immunity are not well understood. We investigated the role of CCR7 in the host defense against acute pulmonary infection with Pseudomonas aeruginosa. We intranasally infected C57BL/6 mice with P. aeruginosa and characterized the expression of CCR7 ligands and the surface expression of CCR7 on pulmonary leukocytes. In response to infection, expression of CCL19 and expression of CCL21 were oppositely regulated, and myeloid dendritic cells upregulated CCR7 expression. We further examined the effects of CCR7 deficiency on the inflammatory response to P. aeruginosa infection. We infected Ccr7−/− and wild-type mice with P. aeruginosa and characterized the accumulation of pulmonary leukocytes, production of proinflammatory mediators, neutrophil activation, and bacterial clearance. CCR7 deficiency led to an accumulation of myeloid dendritic cells and T cells in the lung in response to infection. CCR7 deficiency resulted in higher expression of CD80 and CD86 on dendritic cells; increased production of interleukin-12/23p40 (IL-12/23p40), gamma interferon (IFN-γ), and IL-1α; increased neutrophil respiratory burst; and, ultimately, increased clearance of acute P. aeruginosa infection. In conclusion, our results suggest that CCR7 deficiency results in a heightened proinflammatory environment in response to acute pulmonary P. aeruginosa infection and contributes to more efficient clearance.
Background & Aims
CCL25/CCR9 is a non-promiscuous chemokine/receptor pair and a key regulator of leukocyte migration to the small intestine. We investigated here whether CCL25/CCR9 interactions also play a role in the regulation of inflammatory responses in the large intestine.
Acute inflammation and recovery in wild-type (WT) and CCR9−/− mice was studied in a model of dextran sulfate sodium (DSS)-induced colitis. Distribution studies and phenotypic characterization of dendritic cell subsets and macrophage were performed by flow cytometry. Inflammatory bowel disease (IBD) scores were assessed and expression of inflammatory cytokines was studied at the mRNA and the protein level.
CCL25 and CCR9 are both expressed in the large intestine and are upregulated during DSS colitis. CCR9−/− mice are more susceptible to DSS colitis than WT littermate controls as shown by higher mortality, increased IBD score and delayed recovery. During recovery, the CCR9−/− colonic mucosa is characterized by the accumulation of activated macrophages and elevated levels of Th1/Th17 inflammatory cytokines. Activated plasmacytoid dendritic cells (DCs) accumulate in mesenteric lymph nodes (MLNs) of CCR9−/− animals, altering the local ratio of DC subsets. Upon re-stimulation, T cells isolated from these MLNs secrete significantly higher levels of TNFα, IFNγ, IL2, IL-6 and IL-17A while down modulating IL-10 production.
Our results demonstrate that CCL25/CCR9 interactions regulate inflammatory immune responses in the large intestinal mucosa by balancing different subsets of dendritic cells. These findings have important implications for the use of CCR9-inhibitors in therapy of human IBD as they indicate a potential risk for patients with large intestinal inflammation.
During the development of nephrotoxic nephritis (NTN) in the mouse, we find that a variety of chemokines and chemokine receptors are induced: CCR1 (RANTES, MIP-1α), CCR2 (MCP-1), CCR5 (RANTES, MIP-1α, MIP-1β), CXCR2 (MIP-2), and CXCR3 (IP-10). Their timing of expression indicated that CXCR2 and CCR1 are probably important in the neutrophil-dependent heterologous phase of the disease, whereas CCR1, CCR2, CCR5, and CXCR3 accompany the subsequent mononuclear cell infiltration characteristic of autologous disease. We therefore assessed the role of CCR1 in NTN using CCR1–/– mice. We found that neutrophil accumulation in CCR1–/– mice was comparable to that in wild-type animals but that renal recruitment of CD4+ and CD8+ T cells and macrophages increased significantly. Moreover, CCR1–/– mice developed more severe glomerulonephritis than did controls, with greater proteinuria and blood urea nitrogen, as well as a higher frequency of crescent formation. In addition, CCR1–/– mice showed enhanced Th1 immune responses, including titers of antigen-specific IgG2a antibody, delayed-type hypersensitivity responses, and production of IFN-γ and TNF-α. Lastly, using recombinant proteins and transfected cells that overexpressed CCR1, we demonstrated that MIP-1α, but not RANTES, bound CCR1 and induced cell chemotaxis. Thus, rather than simply promoting leukocyte recruitment during NTN, CCR1 expression profoundly alters the effector phase of glomerulonephritis. Therapeutic targeting of chemokine receptors may, on occasion, exacerbate underlying disease.
J. Clin. Invest. 104:1549–1557 (1999).
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.
Psoriasis is an immune-mediated chronic inflammatory skin disease, characterized by epidermal hyperplasia and infiltration of leukocytes into the dermis and epidermis. IL-23 is expressed in psoriatic skin, and IL-23 injected into the skin of mice produces IL-22-dependent dermal inflammation and acanthosis. The chemokine receptor CCR2 has been implicated in the pathogenesis of several inflammatory diseases, including psoriasis. CCR2-positive cells and the CCR2 ligand, CCL2 are abundant in psoriatic lesions. To examine the requirement of CCR2 in the development of IL-23-induced cutaneous inflammation, we injected the ears of wild-type (WT) and CCR2-deficient (CCR2−/−) mice with IL-23. CCR2−/− mice had increased ear swelling and epidermal thickening, which was correlated with increased cutaneous IL-4 levels and increased numbers of eosinophils within the skin. In addition, TSLP, a cytokine known to promote and amplify T helper cell type 2 (Th2) immune responses, was also increased within the inflamed skin of CCR2−/− mice. Our data suggest that increased levels of TSLP in CCR2−/− mice may contribute to the propensity of these mice to develop increased Th2-type immune responses.
Skin-infiltrating T-cells play a predominant role in allergic and inflammatory skin diseases such as atopic dermatitis, psoriasis and allergic contact dermatitis. These T-cells are attracted by several chemotactic factors including the chemokine CCL5/RANTES, a CC chemokine inducing both the migration and activation of specific leukocyte subsets. CCL5 has been found to be associated with various cell-mediated hypersensitive disorders such as psoriasis, atopic dermatitis and irritant contact dermatitis. We have used two antagonists, the first, Met-CCL5, a dual CCR1/CCR5 antagonist and the second, a variant in which GAG binding is abrogated, 44AANA47-CCL5, which acts as a dominant negative inhibitor of CCL5. The antagonists were tested in two models of contact skin reaction. The first, irritant contact dermatitis (ICD) is a pathological non-specific inflammatory skin condition arising from the release of pro-inflammatory cytokines by keratinocytes in response to haptens, usually chemicals. The second, contact hypersensitivity (CHS) is a T-cell dependent model, mimicking in part the T-cell-mediated skin diseases such as psoriasis. In both models, the CCL5 antagonists showed therapeutic efficacy by reducing swelling by 50% as well as the reduction of soluble mediators in homogenates derived from challenged ears. These results demonstrate that blocking the receptor or the ligand are both effective strategies to inhibit skin inflammation.
During the resolution phase of inflammation, the ‘corpses’ of apoptotic leukocytes are gradually cleared by macrophages. Here we report that during the resolution of peritonitis, the CCR5 chemokine receptor ligands CCL3 and CCL5 persisted in CCR5-deficient mice. CCR5 expression on apoptotic neutrophils and activated apoptotic T cells sequestered and effectively cleared CCL3 and CCL5 from sites of inflammation. CCR5 expression on late apoptotic human polymorphonuclear cells was downregulated by proinflammatory stimuli, including tumor necrosis factor, and was upregulated by ‘proresolution’ lipid mediators, including lipoxin A4, resolvin E1 and protectin D1. Our results suggest that CCR5+ apoptotic leukocytes act as ‘terminators’ of chemokine signaling during the resolution of inflammation.
Intracranial (i.c.) infection of mice with lymphocytic choriomeningitis virus (LCMV) results in anorexic weight loss, mediated by T cells and gamma interferon (IFN-γ). Here, we assessed the role of CD4+ T cells and IFN-γ on immune cell recruitment and proinflammatory cytokine/chemokine production in the central nervous system (CNS) after i.c. LCMV infection. We found that T-cell-depleted mice had decreased recruitment of hematopoietic cells to the CNS and diminished levels of IFN-γ, CCL2 (MCP-1), CCL3 (MIP-1α), and CCL5 (RANTES) in the cerebrospinal fluid (CSF). Mice deficient in IFN-γ had decreased CSF levels of CCL3, CCL5, and CXCL10 (IP-10), and decreased activation of both resident CNS and infiltrating antigen-presenting cells (APCs). The effects of IFN-γ signaling on macrophage lineage cells was assessed using transgenic mice, called “macrophages insensitive to interferon gamma” (MIIG) mice, that express a dominant-negative IFN-γ receptor under the control of the CD68 promoter. MIIG mice had decreased levels of CCL2, CCL3, CCL5, and CXCL10 compared to controls despite having normal numbers of LCMV-specific CD4+ T cells in the CNS. MIIG mice also had decreased recruitment of infiltrating macrophages and decreased activation of both resident CNS and infiltrating APCs. Finally, MIIG mice were significantly protected from LCMV-induced anorexia and weight loss. Thus, these data suggest that CD4+ T-cell production of IFN-γ promotes signaling in macrophage lineage cells, which control (i) the production of proinflammatory cytokines and chemokines, (ii) the recruitment of macrophages to the CNS, (iii) the activation of resident CNS and infiltrating APC populations, and (iv) anorexic weight loss.