Expression Of CD200R1 Research Articles

Monocytes, microglia, and CD200-CD200R1 signaling are essential in the transmission of inflammation from the periphery to the central nervous system.

Peripheral inflammation is known to trigger neuroinflammation and neurodegenerative disease. However, the key components during the propagation of inflammation from the periphery to the central nervous system (CNS) remain unclear. Lipopolysaccharide (LPS) was administered to Sprague-Dawley rats to induce peripheral inflammation. An intravenous injection and an intranigral injection of clodronate liposomes were given to deplete monocytes and microglia, respectively. Recombinant CD200 fusion protein (CD200Fc) or an anti-CD200R1 antibody was injected into the substantia nigra to manipulate the involvement of CD200 and CD200R1. Immunohistochemistry and immunofluorescence staining were used to measure microglial activation and dopaminergic neuronal loss. The expression of brain pro-inflammatory cytokines (i.e., tumor necrosis factor alpha, IL-1β) and CD200-CD200R1 signaling were measured by quantitative RT-PCR. Our data showed that the peripheral LPS injection activated the microglia and induced an increase in the levels of pro-inflammatory cytokines (i.e., tumor necrosis factor alpha, IL-1β). The depletion of either monocytes or microglia suppressed these inflammatory effects that were induced by peripheral LPS administration. The peripheral LPS injection increased the expression of CD200 and CD200R1 in the substantia nigra. Dopaminergic neuronal loss induced by the peripheral LPS injection was accelerated by the blockade of CD200-CD200R1 signaling with an anti-CD200R1 antibody and attenuated by intensifying the signaling with CD200Fc. These results highlight the importance of monocytes, microglia, and CD200-CD200R1 signaling in the transmission of inflammation from the periphery to the CNS.

Expression of CD200R1 and its Ligand CD200 on T-helper Lymphocytes of Pediatric Patients with Ulcerative Colitis and Crohn's Disease.

CD200 and its receptor CD200R are both type I membrane glycoproteins that modulate the activity of myeloid and lymphoid cells, and their interaction is functionally important in the suppression of effector T-cell responses by regulatory T-cells. We aimed to investigate the extent of expression of CD200 and CD200R1 on CD4+ T-cells in blood of children with ulcerative colitis (UC) and Crohn's disease (CD) and to explore their correlations with effector T cell subsets, regulatory T cells (Treg), and routine clinical and serological markers. The frequencies of blood CD4+ expressing CD200 and CD200R1 as well as T-helper CD4+CD25+Foxp3+ Treg, CD4+ IL-17+ (Th17), CD4+ IFN-γ + (Th1), and CD4+IL-4+ (Th2) were estimated by flow cytometry in 23 patients with CD, 14 with UC, and 14 healthy volunteers (HCs). The clinical and inflammatory markers were also investigated. IBD patients showed decreased CD4+CD200R1+ T-cells, whereas, CD4+CD200+ T-cells were significantly higher in patient groups compared with healthy controls. Treg cells were found significantly decreased in the patients with UC and CD compared with healthy controls (both at p < 0.01). The percentage of Th17 was found significantly increased in CD (p < 0.05) compared with UC patients and healthy subjects (p = 0.014). CD200+CD4+ T-cells showed significant positive correlations with ESR, Th1, and Th17 (r = 0.438, p < 0.05; r = 0.411, p < 0.05; r = 0.492, p < 0.01, respectively). CD200R1+CD4+ T-cells correlated positively with Th2 and Treg (r = 0.482, p < 0.01, and r = 0.457, p < 0.01, respectively) and negatively with ESR (r = -0.387, p < 0.01). Our study demonstrates an aberrant expression of CD200/CD200R1 on CD4+ T-cells in IBD patients and these data may have potent pathological significance in IBD pathophysiology.

Reduced Dendritic Cells Expressing CD200R1 in Children with Inflammatory Bowel Disease: Correlation with Th17 and Regulatory T Cells.

Loss of tolerance of the adaptive immune system towards indigenous flora contributes to the development of inflammatory bowel diseases (IBD). Defects in dendritic cell (DC)-mediated innate and adoptive immune responses are conceivable. The aim of this study was to investigate the expression of the inhibitory molecules CD200R1 and their ligand CD200 on DCs, to clarify the role of the DCs in the pathogenesis of IBD. Thirty-seven pediatric IBD patients (23 with Crohn’s disease (CD) and 14 with ulcerative colitis (UC)) with mean age 13.25 ± 2.9 years were included. Fourteen age-matched healthy pediatric volunteers (five males and nine females) served as a control group (HC). The percentage of CD11c+ myeloid dendritic cells (mDCs) and CD123+ plasmacytoid DCs (pDCs) expressing CD200R1 and CD200 were evaluated in peripheral blood using flow cytometry and were correlated with routine biochemical, serological markers, serum levels of cytokines and with the percentages of circulating regulatory T cells (Treg) and CD4+ producing IL-17 (Th17). IBD patients showed a significant decrease in the percentage of pDCs and mDCs expressing CD200R1 compared to that of HC. Patients with UC showed increased expressions of the CD200 molecule on pDCs as compared to HC. DCs expressing CD200R1 were found to be correlated positively with Treg and negatively with TH17 and erythrocyte sedimentation rate (ESR). Our findings suggest that IBD is associated with dysregulation in the CD200R1/CD200 axis and that the decrease in DCs expressing CD200R1 may contribute to the imbalance of Th17 and Treg cells and in the pathogenesis of IBD.

Decreased expression of CD200R3 on mouse basophils as a novel marker for IgG1-mediated anaphylaxis.

IgE-mediated mast cell activation is the trigger of anaphylaxis in humans, whereas it is known that not only IgE but also IgG can induce anaphylaxis in mice. In our preliminary experiments, the expression of a murine basophil identification marker, CD200R3, on antigen-sensitized basophils decreased following specific antigen challenge. Interestingly, this decrease did not always correspond with increased expression of the IgE-mediated basophil activation marker CD200R1. Since IgG as well as IgE plays a role in mouse anaphylaxis, we hypothesized that the observed decrease in CD200R3 on basophils was caused by IgG-mediated cell activation. We attempted to establish whether CD200R3 is a marker of IgG-mediated basophil activation and if its expression is correlated with anaphylaxis in a mouse model. Mouse basophils were stimulated via Fc∊Rs and/or FcγRs, and levels of CD200R1 and CD200R3 were analyzed by flow cytometry. Basophils derived from naive mice were challenged with a natural antigen, β-lactoglobulin, after passive sensitization with anti-β-LG serum or IgG/IgG subclass-depleted antiserum. Systemic anaphylaxis was induced by i.v. injection of anti-FcγRIII/II monoclonal antibody, and CD200R3 expression on peripheral basophils was assessed. Stimulation via Fc∊Rs induced a significant increase in CD200R1 expression but had only a small effect on that of CD200R3. However, anti-FcγRIII/II stimulation reduced CD200R3 expression markedly. In passive sensitization experiments, down-regulation of CD200R3 induced by antigen challenge was strongly negated by the depletion of IgG or IgG1 from antiserum. Intravenous injection of anti-FcγRIII/II induced CD200R3 down-regulation on peripheral basophils, together with a drop in rectal temperature. Lowered CD200R3 expression on basophils is induced by IgG-mediated stimulation via FcγRs. Use of CD200R1 and CD200R3 as activation markers enables the evaluation of murine basophil activation mediated by IgE and IgG, respectively.

Abstract 4001: Interaction of CD200 overexpression on tumor cells with CD200R1 overexpression on stromal cells: An escape from the host immune response in rectal cancer patients

Abstract Introduction: CD200 imparts an immunoregulatory signal through its receptor - CD200R1, leading to the suppression of tumor specific immunity. The mechanism of CD200:CD200R1 signaling pathway is still uncertain. The aim of this study was to investigate the expression pattern and localization of CD200 and its receptor CD200R1 in normal mucosa and rectal cancer patients. Material and Methods: The immunohistochemical expressions and localizations of CD200 and CD200R1 were examined in 140 rectal cancer patients. Seventy nine of 140 underwent the preoperative radiotherapy treatment and the others were untreated prior to the surgery. In addition, 121 matched normal rectal mucosa samples from the same patients were evaluated. Results: CD200 was expressed in normal mucosal epithelium and rectal cancer. Expression of CD200R1 was seen in normal mucosal epithelium and stromal cells of tumor samples. We found significant up-regulation of CD200 in rectal cancer tissues compared to the normal mucosa (P = 0.001). Interestingly, CD200R1 was overexpressed in stromal cells of rectal cancer patients presenting metastases compared to patients without metastases (P = 0.002). However, there is no difference in the expression levels between stromal cells and tumor cells. More than that, the up-regulation of CD2OO in tumor cells and CD200R1 overexpression in stromal cells was observed in 87 % of metastatic rectal cancer patients. These high expression levels of tumoral CD200 and stromal CD200R1 were significantly correlated with lymph node metastasis. Conclusions: Interaction of CD200 and CD200R1 and their expression profile might be useful to follow-up disease progression in terms of carcinogenesis and metastasis. Citation Format: Atil Bisgin, Wen Jian Meng, Gunnar Adell, Xiao Feng Sun. Interaction of CD200 overexpression on tumor cells with CD200R1 overexpression on stromal cells: An escape from the host immune response in rectal cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4001. doi:10.1158/1538-7445.AM2014-4001

Aberrant CD200/CD200R1 expression and its potential role in Th17 cell differentiation, chemotaxis and osteoclastogenesis in rheumatoid arthritis.

CD200/CD200R1 signalling has an immunoregulatory effect on the activation threshold of the inflammatory immune response and maintains immune homeostasis. In this study we evaluated the status of CD200/CD200R1 interaction in patients with RA. The expression of CD200 and CD200R1 was examined by immunohistochemistry and flow cytometry and was compared between RA patients and healthy controls (HCs). Sorted CD4(+) T cells were stained with carboxyfluorescein succinimidyl ester (CFSE) and annexin V-propidium iodide to evaluate the effect of CD200 on cell proliferation and apoptosis. The effect of CD200 on Th17 differentiation, function and osteoclastogenesis was determined by flow cytometry, transwell migration assay and immunocytochemistry, respectively. The proportion of CD200(+) cells and CD200R1(+) cells in peripheral blood mononuclear cells, peripheral CD14(+) cells and CD4(+) T cells was significantly lower in the RA patients than in HCs, whereas the number of CD200(+) cells was higher in synovium from RA patients than in that from HCs. After treatment with infliximab and MTX we found increased expression of peripheral CD200/CD200R1 that correlated with a decrease in the 28-joint DAS. CD200Fc in vitro partially inhibited CD4(+) T cell proliferation, promoted CD4(+) T cell apoptosis, reduced CD4(+) T cell differentiation into Th17 cells and down-regulated CCR6-mediated Th17 chemotaxis in cells from RA patients. In addition, the engagement of the CD200 receptors on CD14(+) cells with CD200Fc in vitro reduced osteoclastogenesis and inhibited CD14(+) cell-driven Th17 differentiation. Abnormal CD200/CD200R1 expression in RA may contribute to abnormal Th17 cell differentiation, chemotaxis and osteoclastogenesis.

CD200R1 and CD200 expression are regulated by PPAR‐γ in activated glial cells

The mechanisms that control microglial activation are of interest, since neuroinflammation, which involves reactive microglia, may be an additional target in the search for therapeutic strategies to treat neurodegenerative diseases. Neuron-microglia interaction through contact-dependent or independent mechanisms is involved in the regulation of the microglial phenotype in both physiological and pathological conditions. The interaction between CD200, which is mainly present in neurons but also in astrocytes, and CD200R1, which is mainly present in microglia, is one of the mechanisms involved in keeping the microglial proinflammatory phenotype under control in physiological conditions. Alterations in the expression of CD200 and CD200R1 have been described in neurodegenerative diseases, but little is known about the mechanism of regulation of these proteins under physiological or pathological conditions. The aim of this work was to study the modulation of CD200 and CD200R1 expression by peroxisome proliferator-activated receptor gamma (PPAR-γ), a transcription factor involved in the control of the inflammatory response. Mouse primary neuronal and glial cultures and neuron-microglia cocultures were treated with the PPAR-γ endogenous ligand 15-deoxy-Δ(12, 14) -prostaglandin J2 (15d-PGJ2 ) in the presence and absence of lipopolysaccharide plus interferon-γ (LPS/IFN-γ)-induced glial activation. We show that 15d-PGJ2 inhibits the pro-inflammatory response and prevents both CD200R1 downregulation and CD200 upregulation in reactive glial cells. In addition, 15d-PGJ2 abrogates reactive-microglia induced neurotoxicity in neuron-microglia cultures through a CD200-CD200R1 dependent mechanism. These results suggest that PPAR-γ modulates CD200 and CD200R1 gene expression and that CD200-CD200R1 interaction is involved in the anti-inflammatory and neuroprotective action of PPAR-γ agonists.

Decreased CD200R expression on monocyte-derived macrophages correlates with Th17/Treg imbalance and disease activity in rheumatoid arthritis patients

CD200 is expressed on various cell types, including T cells, while the CD200 receptor (CD200R) is expressed on myeloid cells such as monocytes-derived macrophages (MDMs). The CD200-CD200R interaction has been shown to play an important role in the prevention of autoimmune disease. Thus, we hypothesized that CD200/CD200R1 is involved in the pathogenesis of rheumatoid arthritis (RA). In total, 35 RA patients and 17 healthy controls (HCs) were enrolled in this study. CD200/CD200R1 expression and Th17/Treg were examined by flow cytometry. Serum levels of interleukin (IL)-2, interferon-γ (IFN-γ), IL-4 and IL-10 were detected by ELISA. Disease activity was evaluated according to the C-reactive protein (CRP) levels, erythrocyte sedimentation rates (ESR) and 28-joint disease activity score (DAS28) scores. Compared with HCs, RA patients exhibited a significantly decreased level of CD200R1 on MDMs. CD200R1 expression correlated negatively with DAS28, ESR, and CRP levels. This abnormal expression was associated with Th17/Treg imbalance in the active RA patients. However, expression of CD200R1 was not correlated with Th1 (IL-2, IFN-γ) or Th2 (IL-4, IL-10) cytokine responses. In this study, we demonstrate a significant correlation between CD200R1(+) cells and disease severity in RA patients, thus indicating the relevance of the CD200/CD200R1 signaling pathway's potential involvement in the pathogenesis of RA.

Formation of distinct chromatin conformation signatures epigenetically regulate macrophage activation

Microbial-lipopolysacharide (LPS), interleukin 4 (IL-4) and interferon gamma (IFN-γ) polarise macrophages into "innate", "alternative" and "classical", activation states by selective gene regulation. Expression of MARCO, CD200, CD200R1 (innate), MRC1 (alternative) and H2-Eb1 (classical) selectively marks these distinct activation states. Epigenetic events drive such activation upon stimuli and here we study one such mechanism, chromatin conformation signatures implicated in long-range chromatin interactions that regulate transcriptional switch and gene expression. The EpiSwitch™ technology was used to identify and analyse potential markers bordering such conformational signatures for these genes and juxtaposition of markers was compared between resting and activated macrophages. LPS, IL-4 and IFN-γ selectively altered chromatin conformations of their responsive genes in wild type, but not in MyD88(-/-), IL-4R(-/-) and IFN-γR(-/-) macrophages. In addition, two distinct conformations were observed in CD200R1 after LPS and IFN-γ stimulation. In summary, signal-specific alterations in chromatin conformation provide biomarkers that identify and determine distinct gene expression programmes during macrophage activation.

CD200‐CD200R1 interaction contributes to neuroprotective effects of anandamide on experimentally induced inflammation

The endocannabinoid anandamide (AEA) is released by macrophages and microglia on pathological neuroinflammatory conditions such as multiple sclerosis (MS). CD200 is a membrane glycoprotein expressed in neurons that suppresses immune activity via its receptor (CD200R) mainly located in macrophages/microglia. CD200-CD200R interactions contribute to the brain immune privileged status. In this study, we show that AEA protects neurons from microglia-induced neurotoxicity via CD200-CD200R interaction. AEA increases the expression of CD200R1 in LPS/IFN-γ activated microglia through the activation of CB(2) receptors. The neuroprotective effect of AEA disappears when microglial cells derive from CD200R1(-/-) mice. We also show that engagement of CD200R1 by CD200Fc decreased the production of the proinflammatory cytokines IL-1β and IL-6, but increased IL-10 in activated microglia. In the chronic phases of Theiler's virus-induced demyelinating disease (TMEV-IDD) the expression of CD200 and CD200R1 was reduced in the spinal cord. AEA-treated animals up-regulated the expression of CD200 and CD200R1, restoring levels found in sham animals together with increased expression of IL-10 and reduced expression of IL-1β and IL-6. Treated animals also improved their motor behavior. Because AEA up-regulated the expression of CD200R1 in microglia, but failed to enhance CD200 in neurons we suggest that AEA-induced up-regulation of CD200 in TMEV-IDD is likely due to IL-10 as this cytokine increases CD200 in neurons. Our findings provide a new mechanism of action of AEA to limit immune response in the inflamed brain.

Histamine release and surface CD200R1 staining as sensitive methods for assessing murine mast cell activation

Mast cells are important effector cells of allergy and are involved in the pathology of many other diseases. Measurement of β-hexosaminidase activity, the most commonly used method for evaluation of murine mast cell activity, requires a large number of cells and thus is of limited utility for studying mast cells in mouse models of disease. In this study we evaluated the sensitivity of histamine release as compared to β-hexosaminidase activity in the measurement of mast cell activation. Whereas a minimum of 6×104 mast cells per ml were required to detect slight increases in β-hexosaminidase activity after anti-IgE and ionomycin stimulation, substantial increases in histamine release could be detected under the same activating conditions with as few as 480 mast cells per ml. These findings demonstrate that measurement of histamine release is substantially more sensitive than assessment of β-hexosaminidase activity for detecting mast cell activation. Additionally, we describe a novel flow cytometric method for detecting murine mast cell activation. When using 7.5×105 peritoneal cells per condition and gating on IgE+c-kit+cells, mast cell expression of surface CD200R1 increased after both IgE and non IgE-mediated activation. This flow cytometric procedure was uncomplicated and rapid, with increases in surface CD200R1 expression appearing after as little as 30min of stimulation time. Measuring histamine release and surface CD200R1 expression are sensitive approaches for detection of murine mast cell activation. Further, both approaches can be done on unpurified peritoneal cell populations. By requiring low numbers of cells, these approaches are ideal for investigating mast cell activation in murine models of disease.

Abstract 3038: Altered Expression Of The Immunomodulatory Proteins Cd200 And Cd200r1 In Lymphoid Tissue Following Ischemic Stroke

Background and Purpose: Previous studies have demonstrated a rapid activation of peripheral immune responses following experimental stroke, marked by increases in pro-inflammatory cytokines, chemokines, and leukocyte entry into the brain, which may exacerbate tissue damage caused by reperfusion. In the CNS, a consequence of the local immune response to stroke is disruption of the immunosuppressant interaction between CD200 ligand (CD200), expressed by CNS-resident cells, and CD200 receptor (CD200R1) on microglia. Microglia are myeloid-derived cells, which serve as endogenous macrophages within the CNS. In models of CNS injury, disruption of the CD200-CD200R1 interaction leads to changes in intracellular signaling that can increase expression of several pro-inflammatory factors. In the present study, we compared gene expression of CD200 and CD200R1 in the bone marrow, a site of immune cell production, between sham and stroke mice. Additionally, we explored CD200 and CD200R1 protein expression in the primary and secondary lymphoid tissues between sham and stroke mice. Methods: Experimental stroke was induced by middle cerebral artery occlusion in male C57BL/6 mice for 90 minutes prior to reperfusion. Mice were sacrificed 5, 24, and 72 hours after stroke. Bone marrow was harvested from femur and RNA was extracted using Trizol®. cDNA was analyzed for CD200 and CD200R1 expression using qPCR. Western blots were performed on protein extracts from spleens and lymph nodes. Results: In the 5-hour cohort, a significant increase in CD200R1 and CD200 expression was observed in the bone marrow of stroke mice compared with sham. Expression of CD200 and CD200R1 was also elevated in secondary lymphoid tissue in stroke mice. In the 72-hour cohort, a significant decrease in CD200 expression was observed in stroke mice compared to sham mice. Within lymphoid tissue, similar trends were also observed for CD200R1. Conclusions: Immediately following stroke injury, CD200 and CD200R1 gene expression levels are altered in bone marrow, thereby enhancing pro-inflammatory signaling and increasing immune cells in peripheral circulation that can migrate into the brain. The subsequent decrease in expression of these proteins in the 72-hour cohort suggests that CD200- and CD200R-expressing cells are depleted in the bone marrow as a result of their activation, mobilization, and recruitment to the brain. Increased CD200 and CD200R expression in the spleen suggest a similar response by the peripheral immune system as the brain signals for the production of anti-inflammatory components. These results suggest that following stroke, bone marrow activation induces a mobilization signal which targets CD200/R-expressing cells to sites of ischemic brain injury, and is consistent with previous observations showing increased CD200R1 protein levels in the brain following stroke.

CD200R1 regulates the severity of arthritis but has minimal impact on the adaptive immune response

CD200R1 is a member of the immunoglobulin supergene family that is thought to play an inhibitory role in immunity. Previous studies have established the anti-arthritic effect of CD200Fc, an agonist of CD200R1. However, the physiological role played by CD200R1 in arthritis remains to be established. The aims of this study are to assess the contribution of endogenous CD200R1 in regulating the severity of arthritis and to determine its role in shaping the immune response to type II collagen within the context of collagen-induced arthritis, an animal model of rheumatoid arthritis. Arthritis was induced in DBA/1 mice by immunization with type II collagen and the kinetics of expression of CD200R1 and CD200 were monitored by quantitative reverse transcription-polymerase chain reaction. Next, a comparison was made between CD200R1(-/-) and wild-type mice in terms of the progression of collagen-induced arthritis, as well as the B and T cell responses to type II collagen. The expression of both CD200R1 and CD200 was increased after immunization and reached maximal levels at the height of the inflammatory response. In addition, the severity of arthritis was increased significantly in CD200R1(-/-) mice compared to wild-type mice. However, little or no differences were observed between CD200R1(-/-) and wild-type mice in terms of the T or B cell responses to type II collagen. It was concluded that the CD200R1/CD200 pathway is up-regulated in arthritis and plays a significant physiological role in regulating the severity of disease. In contrast, CD200R1 plays a minimal role in shaping the immune response to collagen in this model.