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The C3a receptor mediates protection from intestinal ischemia reperfusion injuries by impairing neutrophil mobilization
Abstracts / Immunobiology 217 (2012) 1129–1222
227 The C3a receptor mediates protection from intestinal ischemia reperfusion injuries by impairing neutrophil mobilization Trent M. Woodruff 1 , Mike C.L. Wu 1 , Faith H. Brennan 1 , Rick A. Wetsel 2 , Marc J. Ruitenberg 1 , Stephen M. Taylor 1 1
School of Biomedical Sciences, University of Queensland, Brisbane, Australia 2 Research Center for Immunology and Autoimmune Diseases, The Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, University of Texas Health Science Center at Houston, Houston, TX, USA
The complement system is strongly implicated in the pathology of ischemia-reperfusion (IR) injuries. C3a is a key complement activation fragment, and its receptor, C3aR, is highly expressed on neutrophils, but to date, has no clear role ascribed to its presence on these cells. In this study, we utilized a neutrophil-dependent, animal model of intestinal IR injury to explore the role of C3aR in acute tissue injuries. C3aR deficiency significantly worsened injury outcomes with C3aR−/− mice displaying increased intestinal mucosal damage, hemorrhaging and apoptotic cell death, alongside a significant increase in the number of infiltrating neutrophils. The circulating neutrophil count was dramatically increased in C3aR−/− mice as compared to wild-type mice, indicating a specific role for C3aR in constraining neutrophil mobilization in response to intestinal injury. In support of this, C3aR−/− mice reconstituted with wild-type bone marrow reversed IR pathology back to wildtype levels. By contrast, local pro-inflammatory cytokines were significantly reduced in C3aR−/− mice. C5aR (CD88) antagonism in C3aR−/− mice also reversed the worsened pathology after intestinal IR, but had no effect on circulating neutrophils, highlighting the divergent, physiological antagonistic roles for C3a and C5a in this model. Finally, we demonstrated that activating the C3aR using a potent C3a agonist in vivo reduced neutrophil mobilization and ameliorated intestinal IR pathology in wild-type, but not C3aR−/− mice. Taken together, this study identifies a new role for C3aR in regulating neutrophil mobilization following acute intestinal injury, and suggests C3a agonists could be potential novel therapeutic candidates for acute neutrophil-driven pathologies.
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be equally important in regulating these T-cell responses critical in defending the host against L. monocytogenes. To test this hypothesis, WT mice and mice lacking C3aR were subjected to systemic L. monocytogenes infection. C3aR−/− mice were significantly more sensitive to infection compared to WT mice as demonstrated by decreased survival (14% C3aR−/− vs 66% WT; P = 0.017) and significantly increased bacterial burden in their livers and spleens. Compared to the infected WT mice, the serum of the infected C3aR−/− mice contained significantly increased levels of the Tcell Th1 cytokines, IFN-gamma, TNF-alpha, and IP-10. Despite the increased levels of Th1 cytokines, the C3aR−/− mice had a significant reduction of CD4+, CD8+, CD19+, LY-6G+, and F4/80+ cells in their spleens. TUNEL staining indicated that the reductions of lymphocytes and innate immune cells in the spleen were due to increased apoptosis in the C3aR−/− infected mice. C3aR−/− mice were also significantly impaired in their adaptive immune response to L. monocytogenes, as demonstrated by increased bacterial burden in the livers of re-infected C3aR−/− mice compared to WT mice. Similar to the primary infection, the re-infected C3aR−/− mice had 45% fewer viable splenocytes (P = 0.0002) 3 days post infection compared to WT re-infected mice. The reduced splenocytes correlated with 44% fewer CD4+ cells (P = 0.0011), 35% fewer CD8+ cells (P = 0.036), 37% fewer CD11c+ cells (P = 0.018), 41% fewer CD19+ cells (P = 0.014), and 50% fewer NK1.1+ cells (P = 0.045). Collectively, these data show that (1) C3aR−/− mice are highly susceptible to L. monocytogenes infection despite their having increased Th1 cytokine responses and (2) that C3aR provides host protection against L. monocytogenes infection by preventing L. monocytogenes induced apoptosis of lymphoid and myeloid cells responsible for the innate and memory response to this intracellular bacterium. http://dx.doi.org/10.1016/j.imbio.2012.08.230 229 The complement anaphylatoxin C3a receptor (C3aR) contributes to the inflammatory response in acute dextran sulphate sodium (DSS)-induced colitis in mice Andreas Klos 1 , Elisabeth Wende 1 , Robert Laudeley 1 , Rick A. Wetsel 2 , Silke Glage 3 1
http://dx.doi.org/10.1016/j.imbio.2012.08.229 228 The complement anaphylatoxin C3a is critical in generating both innate and adaptive immune responses to Listeria monocytogenes due to its indispensible role in immune cell survival Stacey L. Mueller-Ortiz, John E. Morales, Amanda Clark, Rick A. Wetsel University of Texas Health Science Center at Houston, Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, Houston, TX, USA Listeria monocytogenes is a Gram-positive intracellular bacterium that is acquired through tainted food and may lead to systemic infection. Newborns are especially sensitive with a 100% mortality rate if the infection occurs in the first 4 days after birth. Robust innate and cellular CD4+ Th1 and CD8+ immune responses must be generated for efficient clearance of this pathogen. Despite the importance of the innate immune system in fighting L. monocytogenes infection, little is known about the role of complement. During the past several years, studies by us and others have demonstrated that C3a on binding C3aR plays key roles in both CD4+ and CD8+ T-cell responses. Therefore, we hypothesized that C3a may
Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School (MHH), Hannover, Germany 2 Brown Foundation Institute of Molecular Medicine, University of Texas, Health Science Center at Houston, TX, USA 3 Institute for Laboratory Animal Science, MHH, Hanover, Germany The incidence of Inflammatory Bowel Diseases (IBD) is increasing. Crohn’s disease and ulcerative colitis impose a serious burden of suffering and frequently lead to inability to work. As treatment options remain limited, the identification of novel therapeutic targets is needed. In animal models of IBD, C5a and its receptor (C5aR) were found to be involved in intestinal inflammation, and antagonist treatment was shown to be beneficial. Here, we assessed the role of the related anaphylatoxin C3aR in IBD, and paid special attention to the influence of the genetic background, by examining BALB/c C3ar−/− as well as C57BL/6 C3ar−/− mice, in a model of dextran sulphate sodium (DSS)-induced colitis. Mice were weighed and clinically scored daily, and were sacrificed after seven days to collect blood and tissue samples. In BALB/c mice lacking C3aR, weight loss, clinical and histological scores, colon shortening, and tissue levels of the pro-inflammatory cytokine IL-6 were significantly lower than in BALB/c wild type mice. BALB/c mice lacking C3aR also had reduced tissue levels of mRNA for the neutrophil chemotactic protein CXCL1/KC, and of the granulocyte marker myeloperoxidase, accordingly. With C57BL/6 mice, tendencies corresponding to the
227 The C3a receptor mediates protection from intestinal ischemia reperfusion injuries by impairing neutrophil mobilization Trent M. Woodruff 1 , Mike C.L. Wu 1 , Faith H. Brennan 1 , Rick A. Wetsel 2 , Marc J. Ruitenberg 1 , Stephen M. Taylor 1 1
School of Biomedical Sciences, University of Queensland, Brisbane, Australia 2 Research Center for Immunology and Autoimmune Diseases, The Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, University of Texas Health Science Center at Houston, Houston, TX, USA
The complement system is strongly implicated in the pathology of ischemia-reperfusion (IR) injuries. C3a is a key complement activation fragment, and its receptor, C3aR, is highly expressed on neutrophils, but to date, has no clear role ascribed to its presence on these cells. In this study, we utilized a neutrophil-dependent, animal model of intestinal IR injury to explore the role of C3aR in acute tissue injuries. C3aR deficiency significantly worsened injury outcomes with C3aR−/− mice displaying increased intestinal mucosal damage, hemorrhaging and apoptotic cell death, alongside a significant increase in the number of infiltrating neutrophils. The circulating neutrophil count was dramatically increased in C3aR−/− mice as compared to wild-type mice, indicating a specific role for C3aR in constraining neutrophil mobilization in response to intestinal injury. In support of this, C3aR−/− mice reconstituted with wild-type bone marrow reversed IR pathology back to wildtype levels. By contrast, local pro-inflammatory cytokines were significantly reduced in C3aR−/− mice. C5aR (CD88) antagonism in C3aR−/− mice also reversed the worsened pathology after intestinal IR, but had no effect on circulating neutrophils, highlighting the divergent, physiological antagonistic roles for C3a and C5a in this model. Finally, we demonstrated that activating the C3aR using a potent C3a agonist in vivo reduced neutrophil mobilization and ameliorated intestinal IR pathology in wild-type, but not C3aR−/− mice. Taken together, this study identifies a new role for C3aR in regulating neutrophil mobilization following acute intestinal injury, and suggests C3a agonists could be potential novel therapeutic candidates for acute neutrophil-driven pathologies.
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be equally important in regulating these T-cell responses critical in defending the host against L. monocytogenes. To test this hypothesis, WT mice and mice lacking C3aR were subjected to systemic L. monocytogenes infection. C3aR−/− mice were significantly more sensitive to infection compared to WT mice as demonstrated by decreased survival (14% C3aR−/− vs 66% WT; P = 0.017) and significantly increased bacterial burden in their livers and spleens. Compared to the infected WT mice, the serum of the infected C3aR−/− mice contained significantly increased levels of the Tcell Th1 cytokines, IFN-gamma, TNF-alpha, and IP-10. Despite the increased levels of Th1 cytokines, the C3aR−/− mice had a significant reduction of CD4+, CD8+, CD19+, LY-6G+, and F4/80+ cells in their spleens. TUNEL staining indicated that the reductions of lymphocytes and innate immune cells in the spleen were due to increased apoptosis in the C3aR−/− infected mice. C3aR−/− mice were also significantly impaired in their adaptive immune response to L. monocytogenes, as demonstrated by increased bacterial burden in the livers of re-infected C3aR−/− mice compared to WT mice. Similar to the primary infection, the re-infected C3aR−/− mice had 45% fewer viable splenocytes (P = 0.0002) 3 days post infection compared to WT re-infected mice. The reduced splenocytes correlated with 44% fewer CD4+ cells (P = 0.0011), 35% fewer CD8+ cells (P = 0.036), 37% fewer CD11c+ cells (P = 0.018), 41% fewer CD19+ cells (P = 0.014), and 50% fewer NK1.1+ cells (P = 0.045). Collectively, these data show that (1) C3aR−/− mice are highly susceptible to L. monocytogenes infection despite their having increased Th1 cytokine responses and (2) that C3aR provides host protection against L. monocytogenes infection by preventing L. monocytogenes induced apoptosis of lymphoid and myeloid cells responsible for the innate and memory response to this intracellular bacterium. http://dx.doi.org/10.1016/j.imbio.2012.08.230 229 The complement anaphylatoxin C3a receptor (C3aR) contributes to the inflammatory response in acute dextran sulphate sodium (DSS)-induced colitis in mice Andreas Klos 1 , Elisabeth Wende 1 , Robert Laudeley 1 , Rick A. Wetsel 2 , Silke Glage 3 1
http://dx.doi.org/10.1016/j.imbio.2012.08.229 228 The complement anaphylatoxin C3a is critical in generating both innate and adaptive immune responses to Listeria monocytogenes due to its indispensible role in immune cell survival Stacey L. Mueller-Ortiz, John E. Morales, Amanda Clark, Rick A. Wetsel University of Texas Health Science Center at Houston, Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, Houston, TX, USA Listeria monocytogenes is a Gram-positive intracellular bacterium that is acquired through tainted food and may lead to systemic infection. Newborns are especially sensitive with a 100% mortality rate if the infection occurs in the first 4 days after birth. Robust innate and cellular CD4+ Th1 and CD8+ immune responses must be generated for efficient clearance of this pathogen. Despite the importance of the innate immune system in fighting L. monocytogenes infection, little is known about the role of complement. During the past several years, studies by us and others have demonstrated that C3a on binding C3aR plays key roles in both CD4+ and CD8+ T-cell responses. Therefore, we hypothesized that C3a may
Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School (MHH), Hannover, Germany 2 Brown Foundation Institute of Molecular Medicine, University of Texas, Health Science Center at Houston, TX, USA 3 Institute for Laboratory Animal Science, MHH, Hanover, Germany The incidence of Inflammatory Bowel Diseases (IBD) is increasing. Crohn’s disease and ulcerative colitis impose a serious burden of suffering and frequently lead to inability to work. As treatment options remain limited, the identification of novel therapeutic targets is needed. In animal models of IBD, C5a and its receptor (C5aR) were found to be involved in intestinal inflammation, and antagonist treatment was shown to be beneficial. Here, we assessed the role of the related anaphylatoxin C3aR in IBD, and paid special attention to the influence of the genetic background, by examining BALB/c C3ar−/− as well as C57BL/6 C3ar−/− mice, in a model of dextran sulphate sodium (DSS)-induced colitis. Mice were weighed and clinically scored daily, and were sacrificed after seven days to collect blood and tissue samples. In BALB/c mice lacking C3aR, weight loss, clinical and histological scores, colon shortening, and tissue levels of the pro-inflammatory cytokine IL-6 were significantly lower than in BALB/c wild type mice. BALB/c mice lacking C3aR also had reduced tissue levels of mRNA for the neutrophil chemotactic protein CXCL1/KC, and of the granulocyte marker myeloperoxidase, accordingly. With C57BL/6 mice, tendencies corresponding to the