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Tetsuro Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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Involvement of cross-linked ribosomal protein S19 oligomers and C5a Receptor in definitive erythropoiesis
Experimental and molecular pathology, 2013Co-Authors: Jun Chen, Umeko Semba, Rui Zhao, Masato Oda, Tomoyasu Suzuki, Ken Toba, Shin-ichiro Hattori, Seiji Okada, Tetsuro YamamotoAbstract:We performed a series of experiments under a working hypothesis that cross-linked oligomers of ribosomal protein S19 (RP S19) play an essential role in definitive erythropoiesis as a ligand of the C5a Receptor of erythroblasts and macrophages. We found molecules functionally and immunologically indistinguishable from RP S19 oligomers in the extracellular fluid of porcine and guinea pig bone marrow. When an increased hematopoietic state was induced in guinea pigs by bloodletting, the bone marrow RP S19 oligomer concentration was concomitantly increased. However, when the RP S19 oligomers were immunologically neutralized or the C5a Receptor was pharmacologically antagonized, hyper-erythropoiesis induced by bloodletting was prevented and the anemic state was retarded in guinea pigs. When the RP S19 oligomers were neutralized in mice after bloodletting, the reactive hyper proliferation of erythroblasts in the spleen was prevented. Proerythroblasts and erythroblasts prepared by bone marrow aspiration from healthy individuals were found to express significant levels of the C5a Receptor and type 2 transglutaminase genes. Majority of erythroblasts in cord blood of healthy newborns bore the C5a Receptor. Taken together, these results support our hypothesis.
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Pivotal Advance: Interconversion between pure chemotactic ligands and chemoattractant/secretagogue ligands of neutrophil C5a Receptor by a single amino acid substitution.
Journal of leukocyte biology, 2010Co-Authors: Nan Jia, Umeko Semba, Norikazu Nishino, Hiroshi Nishiura, Akihiko Kuniyasu, Tienabe K. Nsiama, Tetsuro YamamotoAbstract:Skp derived from Escherichia coli attracts leukocytes as a pure chemotactic ligand of the C5a Receptor [1]. We identified the submolecular region of Skp that binds and activates the C5a Receptor to be -Gln103-Asp104-Arg105- using synthetic peptide fragments and site-directed mutants of Skp. As the C5a amino acid residue equivalent to Gln103 of Skp is Leu72, we prepared a Gln103Leu-Skp mutant as a recombinant protein. With this mutation, Skp gained secretagogue functions including induction of the respiratory burst and granule release reactions and leukotriene generation, in addition to the chemoattraction displayed by C5a. However, when we substituted Leu72 with Gln in C5a, the L72Q-C5a mutant largely lost its secretagogue function. These functional conversions were reproduced using synthetic peptides mimicking the Receptor-binding/-activating regions of the recombinant proteins. Receptor-binding assays using the mimicking peptides demonstrated only a small difference between the Leu72-C5a and Gln72-C5a peptides. Consistently, L72Q-C5a apparently antagonized C5a secretagogue function. These results indicate that the difference between a chemotactic response and a combined chemotactic/secretory response can be attributed not to the nature of the Receptor but to guidance by the ligand, at least in the case of C5a Receptor-mediated leukocyte responses.
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Roles of the ribosomal protein S19 dimer and the C5a Receptor in pathophysiological functions of phagocytic leukocytes.
Pathology international, 2007Co-Authors: Tetsuro YamamotoAbstract:Monocytes and neutrophils, the major phagocytic leukocytes, migrate to inflammatory sites by sensing chemoattractants such as anaphylatoxin C5a with membrane Receptors such as C5a Receptor. Upon stimulation, the leukocytes increase cytoplasmic Ca(2+) concentration and generate radical oxygen species. These leukocytes have different functions in inflammation. Neutrophils migrate more rapidly and induce vascular plasma leakage upon infiltration. Monocytes infiltrate tissue more slowly but have superior capacities of phagocytosis and antigen presentation. There must be mechanisms to separately recruit the leukocyte species at an inflammatory site. Ribosomal protein S19 (RP S19) is a component of ribosome. During apoptosis, RP S19 is dimerized and obtains a ligand capacity to C5a Receptor. The RP S19 dimer attracts monocytes to phagocytically clear the apoptotic cells that released the dimer molecules. The phagocytic monocytes/macrophages then translocate to regional lymph nodes and present apoptotic cell-derived antigens. Oppositely, the RP S19 dimer inhibits C5a-induced neutrophil migration and promotes apoptosis of neutrophils via the C5a Receptor. The RP S19 dimer seems to prevent excessive tissue destruction induced by neutrophils. Skp is a molecular chaperon of Gram-negative bacteria. Skp also attracts monocytes and neutrophils as a ligand of C5a Receptor. However, it promotes neither cytoplasmic Ca(2+) enhancement nor radical oxygen generation.
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S19 ribosomal protein dimer augments metal-induced apoptosis in a mouse fibroblastic cell line by ligation of the C5a Receptor.
Journal of cellular biochemistry, 2005Co-Authors: Hiroshi Nishiura, Jörg Zwirner, Yoko Shibuya, Sumio Tanase, Noriko Futa, Tamami Sakamoto, Adrian Higginbottom, Peter N. Monk, Tetsuro YamamotoAbstract:To analyze the role of S19 ribosomal protein (RP S19) in apoptosis, murine NIH3T3 were transfected with either hemagglutinin peptide-tagged (HA) wild-type human RP S19 or a mutant (Gln137Asn) that is resistant to transglutaminase-catalyzed cross-linked-dimerization. Transfection with the mutant HA-RP S19 inhibited manganese (II) (Mn II)-induced apoptosis whereas the wild-type HA-RP S19 augmented apoptosis and a mock transfection had no effect. Release of the wild-type HA-RP S19 dimer but not the mutant HA-RP S19 was observed during the apoptosis. The reduced rate of apoptosis of the cells transfected with the mutant HA-RP S19 was overcome by addition of extracellular wild-type RP S19 dimer. The apoptosis rates in cells transfected with either form of human HA-RP S19 and in mock transfectants were reduced to about 40% by the presence of anti-RP S19 antibody in the culture medium. Immunofluorescence staining and fluorescence-activated cell sorting (FACS) analysis showed that the cell surface expression of the Receptor for cross-linked RP S19 dimer, C5a Receptor, increased during apoptosis, concomitant with phosphatidylserine exposure. The expression of the C5a Receptor gene also increased twofold. Apoptosis rates in the transfected and control cell lines were also reduced by the presence of an anti-mouse C5a Receptor monoclonal antibody or of a peptide C5a Receptor antagonist. These results indicated the presence of an RP S19 dimer- and C5a Receptor-mediated autocrine-type augmentation mechanism during Mn II-induced apoptosis in the mouse fibroblastic cell line. In contrast to the RP S19 dimer, C5a actually inhibited apoptosis, suggesting that signaling through the C5a Receptor varies depending on the ligand bound.
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Agonist and antagonist dual effect of the cross-linked S19 ribosomal protein dimer in the C5a Receptor-mediated respiratory burst reaction of phagocytic leukocytes.
Inflammation research : official journal of the European Histamine Research Society ... [et al.], 2005Co-Authors: I. Revollo, Yoko Shibuya, Norikazu Nishino, Hiroshi Nishiura, Y. Oda, Tetsuro YamamotoAbstract:Objective: To examine the behavior of the crosslinked dimer of S19 ribosomal protein (RP S19), a natural C5a Receptor ligand, in the C5a Receptor-mediated respiratory burst reaction of monocytes and neutrophils.
Stephen M. Taylor - One of the best experts on this subject based on the ideXlab platform.
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Oral treatment with complement factor C5a Receptor (CD88) antagonists inhibits experimental periodontitis in rats.
Journal of periodontal research, 2011Co-Authors: Torbjørn Breivik, Stephen M. Taylor, Yngvar Gundersen, Per Gjermo, Trent M. Woodruff, P. K. OpstadAbstract:Background and Objective: The complement activation product 5a (C5a) is a potent mediator of the innate immune response to infection, and may thus also importantly determine the development of periodontitis. The present study was designed to explore the effect of several novel, potent and orally active C5a Receptor (CD88) antagonists (C5aRAs) on the development of ligature-induced periodontitis in an animal model.
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role of complement C5a in mechanical inflammatory hypernociception potential use of C5a Receptor antagonists to control inflammatory pain
British Journal of Pharmacology, 2008Co-Authors: E Ting, Stephen M. Taylor, Trent M. Woodruff, Ana Tereza Gomes Guerrero, Thiago M Cunha, Waldiceu A Verri, Fernando Q Cunha, S H FerreiraAbstract:Background and purpose: C5a, a complement activation product, exhibits a broad spectrum of inflammatory activities particularly neutrophil chemoattraction. Herein, the role of C5a in the genesis of inflammatory hypernociception was investigated in rats and mice using the specific C5a Receptor antagonist PMX53 (AcF-[OP(D-Cha)WR]). Experimental approach: Mechanical hypernociception was evaluated with a modification of the Randall–Selitto test in rats and electronic pressure meter paw test in mice. Cytokines were measured by ELISA and neutrophil migration was determined by myeloperoxidase activity. Key results: Local pretreatment of rats with PMX53 (60–180 μg per paw) inhibited zymosan-, carrageenan-, lipopolysaccharide (LPS)- and antigen-induced hypernociception. These effects were associated with C5a Receptor blockade since PMX53 also inhibited the hypernociception induced by zymosan-activated serum and C5a but not by the direct-acting hypernociceptive mediators, prostaglandin E2 and dopamine. Underlying the C5a hypernociceptive mechanisms, PMX53 did not alter the cytokine release induced by inflammatory stimuli. However, PMX53 inhibited cytokine-induced hypernociception. PMX53 also inhibited the recruitment of neutrophils induced by zymosan but not by carrageenan or LPS, indicating an involvement of neutrophils in the hypernociceptive effect of C5a. Furthermore, the C5a-induced hypernociception was reduced in neutrophil-depleted rats. Extending these findings in rats, blocking C5a Receptors also reduced zymosan-induced joint hypernociception in mice. Conclusions and implications: These results suggest that C5a is an important inflammatory hypernociceptive mediator, acting by a mechanism independent of hypernociceptive cytokine release, but dependent on the presence of neutrophils. Therefore, we suggest that inhibiting the action of C5a has therapeutic potential in the control of inflammatory pain. British Journal of Pharmacology (2008) 153, 1043–1053; doi:10.1038/sj.bjp.0707640; published online 17 December 2007
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Blockade of the C5a Receptor fails to protect against experimental autoimmune encephalomyelitis in rats.
Clinical and experimental immunology, 2004Co-Authors: Bryan Paul Morgan, Mark R. Griffiths, H. Khanom, Stephen M. Taylor, James W. NealAbstract:Complement activation contributes to inflammation and tissue damage in human demyelinating diseases and in rodent models of demyelination. Inhibitors of complement activation ameliorate disease in the rat model antibody-dependent experimental autoimmune encephalomyelitis and rats unable to generate the membrane attack complex of complement develop inflammation without demyelination. The role of the highly active chemotactic and anaphylactic complement-derived peptide C5a in driving inflammation and pathology in rodent models of demyelination has been little explored. Here we have used a small molecule C5a Receptor antagonist, AcF-[OPdChaWR], to examine the effects of C5a Receptor blockade in rat models of brain inflammation and demyelination. C5a Receptor antagonist therapy completely blocked neutrophil response to C5a in vivo but had no effect on clinical disease or resultant pathology in either inflammatory or demyelinating rat models. We conclude that C5a is not required for disease induction or perpetuation in these strongly complement-dependent disease models.
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A small molecule C5a Receptor antagonist protects kidneys from ischemia/reperfusion injury in rats.
Kidney international, 2003Co-Authors: Thiruma V. Arumugam, Ian A. Shiels, Anna J. Strachan, Giovani Abbenante, David P. Fairlie, Stephen M. TaylorAbstract:A small molecule C5a Receptor antagonist protects kidneys from ischemia/reperfusion injury in rats. Background C5a has been implicated in numerous pathophysiological conditions, including ischemia/reperfusion (I/R) injury of the kidney. We examined whether a novel and specific C5a Receptor antagonist, the cyclic compound AcF-[OPdChaWR] could moderate I/R-induced renal injury in rats. Methods Female Wistar rats were subjected to renal ischemia (60 min) and reperfusion (5 h). Rats were treated with either 1 mg/kg IV in 5% ethanol/saline or 10 mg/kg PO in 25% ethanol/saline prior to ischemia. I/R injury was characterized by significant tissue hemorrhage with increased microvascular permeability, elevated renal tissue levels of tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO), increased serum levels of creatinine and aspartate aminotransferase (AST) and hematuria. Results Pre-ischemic treatment with the C5a Receptor (C5aR) antagonist (1 mg/kg IV or 10 mg/kg PO) substantially inhibited or prevented I/R-induced hematuria, vascular leakage, tissue levels of TNF-α and MPO, and serum levels of AST and creatinine. Histological examination of kidneys from antagonist pretreated I/R animals showed a marked reduction in tissue damage compared to drug-free I/R rats. This antagonist, however, did not inhibit complement-mediated lysis of red blood cells, suggesting unimpaired formation of the membrane attack complex (MAC). Conclusions The results demonstrate for the first time that a selective antagonist of both human and rat C5a Receptors, given either intravenously or orally, significantly protects the kidney from I/R injury in the rat. We conclude that C5a is an important pathogenic agent in renal I/R injury, and that C5a Receptor antagonists may be useful therapeutic agents for the pretreatment of anticipated renal reperfusion injury in humans.
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a small molecule C5a Receptor antagonist protects kidneys from ischemia reperfusion injury in rats
Kidney International, 2003Co-Authors: Thiruma V. Arumugam, Ian A. Shiels, Anna J. Strachan, Giovani Abbenante, David P. Fairlie, Stephen M. TaylorAbstract:A small molecule C5a Receptor antagonist protects kidneys from ischemia/reperfusion injury in rats. Background C5a has been implicated in numerous pathophysiological conditions, including ischemia/reperfusion (I/R) injury of the kidney. We examined whether a novel and specific C5a Receptor antagonist, the cyclic compound AcF-[OPdChaWR] could moderate I/R-induced renal injury in rats. Methods Female Wistar rats were subjected to renal ischemia (60 min) and reperfusion (5 h). Rats were treated with either 1 mg/kg IV in 5% ethanol/saline or 10 mg/kg PO in 25% ethanol/saline prior to ischemia. I/R injury was characterized by significant tissue hemorrhage with increased microvascular permeability, elevated renal tissue levels of tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO), increased serum levels of creatinine and aspartate aminotransferase (AST) and hematuria. Results Pre-ischemic treatment with the C5a Receptor (C5aR) antagonist (1 mg/kg IV or 10 mg/kg PO) substantially inhibited or prevented I/R-induced hematuria, vascular leakage, tissue levels of TNF-α and MPO, and serum levels of AST and creatinine. Histological examination of kidneys from antagonist pretreated I/R animals showed a marked reduction in tissue damage compared to drug-free I/R rats. This antagonist, however, did not inhibit complement-mediated lysis of red blood cells, suggesting unimpaired formation of the membrane attack complex (MAC). Conclusions The results demonstrate for the first time that a selective antagonist of both human and rat C5a Receptors, given either intravenously or orally, significantly protects the kidney from I/R injury in the rat. We conclude that C5a is an important pathogenic agent in renal I/R injury, and that C5a Receptor antagonists may be useful therapeutic agents for the pretreatment of anticipated renal reperfusion injury in humans.
Thomas J. Baranski - One of the best experts on this subject based on the ideXlab platform.
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A Comprehensive Structure-Function Map of the Intracellular Surface of the Human C5a Receptor I. IDENTIFICATION OF CRITICAL RESIDUES
The Journal of biological chemistry, 2006Co-Authors: Marissa L. Matsumoto, Kirk Narzinski, Philip D. Kiser, Gregory V. Nikiforovich, Thomas J. BaranskiAbstract:G protein-coupled Receptors are one of the largest protein families in nature; however, the mechanisms by which they activate G proteins are still poorly understood. To identify residues on the intracellular face of the human C5a Receptor that are involved in G protein activation, we performed a genetic analysis of each of the three intracellular loops and the carboxyl-terminal tail of the Receptor. Amino acid substitutions were randomly incorporated into each loop, and functional Receptors were identified in yeast. The third intracellular loop contains the largest number of preserved residues (positions resistant to amino acid substitutions), followed by the second loop, the first loop, and lastly the carboxyl terminus. Surprisingly, complete removal of the carboxyl-terminal tail did not impair C5a Receptor signaling. When mapped onto a three-dimensional structural model of the inactive state of the C5a Receptor, the preserved residues reside on one half of the intracellular surface of the Receptor, creating a potential activation face. Together these data provide one of the most comprehensive functional maps of the intracellular surface of any G protein-coupled Receptor to date.
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genetic analysis of the first and third extracellular loops of the C5a Receptor reveals an essential wxfg motif in the first loop
Journal of Biological Chemistry, 2006Co-Authors: Jeffery M Klco, Gregory V. Nikiforovich, Thomas J. BaranskiAbstract:The extracellular loops of G protein-coupled Receptors (GPCRs) frequently contain binding sites for peptide ligands. However, the mechanism of Receptor activation following ligand binding and the influence of the extracellular loops in other aspects of Receptor function are poorly understood. Here we report a structure-function analysis of the first and third extracellular loops of the human C5a Receptor, a GPCR that binds a 74-amino acid peptide ligand. Amino acid substitutions were randomly incorporated into each loop, and functional Receptors were identified in yeast. The first extracellular loop contains a large number of positions that cannot tolerate amino acid substitutions, especially residues within the WXFG motif found in many rhodopsin-like GPCRs, yet disruption of these residues does not alter C5a binding affinity. These results demonstrate an unanticipated role for the first extracellular loop, and the WXFG motif in particular, in ligand-mediated activation of the C5a Receptor. This motif likely serves a similar role in other GPCRs. The third extracellular loop, in contrast, contains far fewer preserved residues and appears to play a less essential role in Receptor activation.
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Essential role for the second extracellular loop in C5a Receptor activation
Nature Structural & Molecular Biology, 2005Co-Authors: Jeffery M Klco, Kirk Narzinski, Christina B Wiegand, Thomas J. BaranskiAbstract:More than 90% of G protein–coupled Receptors (GPCRs) contain a disulfide bridge that tethers the second extracellular loop (EC2) to the third transmembrane helix. To determine the importance of EC2 and its disulfide bridge in Receptor activation, we subjected this region of the complement factor 5a Receptor (C5aR) to random saturation mutagenesis and screened for functional Receptors in yeast. The cysteine forming the disulfide bridge was the only conserved residue in the EC2-mutated Receptors. Notably, ∼80% of the functional Receptors exhibited potent constitutive activity. These results demonstrate an unexpected role for EC2 as a negative regulator of C5a Receptor activation. We propose that in other GPCRs, EC2 might serve a similar role by stabilizing the inactive state of the Receptor.
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C5a Receptor oligomerization. II. Fluorescence resonance energy transfer studies of a human G protein-coupled Receptor expressed in yeast.
The Journal of biological chemistry, 2003Co-Authors: Desiree H. Floyd, Adi Geva, Stephen P. Bruinsma, Mark C. Overton, Kendall J. Blumer, Thomas J. BaranskiAbstract:Recent studies demonstrate that members of the superfamily of G protein-coupled Receptors (GPCRs) form oligomers both in vitro and in vivo. The mechanisms by which GPCRs oligomerize and the roles of accessory proteins in this process are not well understood. We used disulfide-trapping experiments to show that C5a Receptors, expressed in mammalian cells, reside in membranes as oligomers (Klco, J. M., Lassere, T. B., and Baranski, T. J. (2003) J. Biol. Chem. 278, 35345-35353). To begin to address how C5a Receptors form oligomers, we now use fluorescence resonance energy transfer experiments on human C5a Receptors expressed in the lower eukaryote Saccharomyces cerevisiae. C5a Receptors tagged with variants of the green fluorescent protein display energy transfer in intact yeast, demonstrating that mammalian accessory proteins are not required for C5a Receptor oligomerization. In both intact yeast cells and membrane preparations, agonist does not affect FRET efficiency, and little energy transfer is observed between the C5a Receptor and a co-expressed yeast pheromone Receptor (encoded by STE2), indicating that C5a Receptor oligomerization is both Receptor-specific and constitutive. FRET studies performed on fractionated membranes demonstrate similar levels of energy transfer between tagged C5a Receptors in endoplasmic reticulum compared with plasma membrane, and urea washing of membranes has little effect on the extent of energy transfer. The oligomerization of C5a Receptors expressed in yeast displays characteristics similar to those observed for other GPCRs studied in mammalian cells. This model system should prove useful for further studies to define mechanisms of oligomerization of mammalian GPCRs.
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C5a Receptor activation genetic identification of critical residues in four transmembrane helices
Journal of Biological Chemistry, 1999Co-Authors: Thomas J. Baranski, Paul Herzmark, Olivier Lichtarge, Basil O Gerber, Joshua Trueheart, Elaine C Meng, Taroh Iiri, Soren P Sheikh, Henry R BourneAbstract:Hormones and sensory stimuli activate serpentine Receptors, transmembrane switches that relay signals to heterotrimeric guanine nucleotide-binding proteins (G proteins). To understand the switch mechanism, we subjected 93 amino acids in transmembrane helices III, V, VI, and VII of the human chemoattractant C5a Receptor to random saturation mutagenesis. A yeast selection identified 121 functioning mutant Receptors, containing a total of 523 amino acid substitutions. Conserved hydrophobic residues are located on helix surfaces that face other helices in a modeled seven-helix bundle (Baldwin, J. M., Schertler, G. F., and Unger, V. M. (1997) J. Mol. Biol. 272, 144-164), whereas surfaces predicted to contact the surrounding lipid tolerate many substitutions. Our analysis identified 25 amino acid positions resistant to nonconservative substitutions. These appear to comprise two distinct components of the Receptor switch, a surface at or near the extracellular membrane interface and a core cluster in the cytoplasmic half of the bundle. Twenty-one of the 121 mutant Receptors exhibit constitutive activity. Amino acids substitutions in these activated Receptors predominate in helices III and VI; other activating mutations truncate the Receptor near the extracellular end of helix VI. These results identify key elements of a general mechanism for the serpentine Receptor switch.
David P. Fairlie - One of the best experts on this subject based on the ideXlab platform.
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the ribosomal protein s19 suppresses antitumor immune responses via the complement C5a Receptor 1
Journal of Immunology, 2017Co-Authors: Maciej M Markiewski, David P. Fairlie, Surya Kumari Vadrevu, Sharad K Sharma, Navin K Chintala, Shanawaz M Ghouse, Yvonne Paterson, Aristotelis Astrinidis, Magdalena KarbowniczekAbstract:Relatively little is known about factors that initiate immunosuppression in tumors and act at the interface between tumor cells and host cells. In this article, we report novel immunosuppressive properties of the ribosomal protein S19 (RPS19), which is upregulated in human breast and ovarian cancer cells and released from apoptotic tumor cells, whereupon it interacts with the complement C5a Receptor 1 expressed on tumor infiltrating myeloid-derived suppressor cells. This interaction promotes tumor growth by facilitating recruitment of these cells to tumors. RPS19 also induces the production of immunosuppressive cytokines, including TGF-β, by myeloid-derived suppressor cells in tumor-draining lymph nodes, leading to T cell responses skewed toward Th2 phenotypes. RPS19 promotes generation of regulatory T cells while reducing infiltration of CD8 + T cells into tumors. Reducing RPS19 in tumor cells or blocking the C5a Receptor 1–RPS19 interaction decreases RPS19-mediated immunosuppression, impairs tumor growth, and delays the development of tumors in a transgenic model of breast cancer. This work provides initial preclinical evidence for targeting RPS19 for anticancer therapy enhancing antitumor T cell responses.
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A small molecule C5a Receptor antagonist protects kidneys from ischemia/reperfusion injury in rats.
Kidney international, 2003Co-Authors: Thiruma V. Arumugam, Ian A. Shiels, Anna J. Strachan, Giovani Abbenante, David P. Fairlie, Stephen M. TaylorAbstract:A small molecule C5a Receptor antagonist protects kidneys from ischemia/reperfusion injury in rats. Background C5a has been implicated in numerous pathophysiological conditions, including ischemia/reperfusion (I/R) injury of the kidney. We examined whether a novel and specific C5a Receptor antagonist, the cyclic compound AcF-[OPdChaWR] could moderate I/R-induced renal injury in rats. Methods Female Wistar rats were subjected to renal ischemia (60 min) and reperfusion (5 h). Rats were treated with either 1 mg/kg IV in 5% ethanol/saline or 10 mg/kg PO in 25% ethanol/saline prior to ischemia. I/R injury was characterized by significant tissue hemorrhage with increased microvascular permeability, elevated renal tissue levels of tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO), increased serum levels of creatinine and aspartate aminotransferase (AST) and hematuria. Results Pre-ischemic treatment with the C5a Receptor (C5aR) antagonist (1 mg/kg IV or 10 mg/kg PO) substantially inhibited or prevented I/R-induced hematuria, vascular leakage, tissue levels of TNF-α and MPO, and serum levels of AST and creatinine. Histological examination of kidneys from antagonist pretreated I/R animals showed a marked reduction in tissue damage compared to drug-free I/R rats. This antagonist, however, did not inhibit complement-mediated lysis of red blood cells, suggesting unimpaired formation of the membrane attack complex (MAC). Conclusions The results demonstrate for the first time that a selective antagonist of both human and rat C5a Receptors, given either intravenously or orally, significantly protects the kidney from I/R injury in the rat. We conclude that C5a is an important pathogenic agent in renal I/R injury, and that C5a Receptor antagonists may be useful therapeutic agents for the pretreatment of anticipated renal reperfusion injury in humans.
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a small molecule C5a Receptor antagonist protects kidneys from ischemia reperfusion injury in rats
Kidney International, 2003Co-Authors: Thiruma V. Arumugam, Ian A. Shiels, Anna J. Strachan, Giovani Abbenante, David P. Fairlie, Stephen M. TaylorAbstract:A small molecule C5a Receptor antagonist protects kidneys from ischemia/reperfusion injury in rats. Background C5a has been implicated in numerous pathophysiological conditions, including ischemia/reperfusion (I/R) injury of the kidney. We examined whether a novel and specific C5a Receptor antagonist, the cyclic compound AcF-[OPdChaWR] could moderate I/R-induced renal injury in rats. Methods Female Wistar rats were subjected to renal ischemia (60 min) and reperfusion (5 h). Rats were treated with either 1 mg/kg IV in 5% ethanol/saline or 10 mg/kg PO in 25% ethanol/saline prior to ischemia. I/R injury was characterized by significant tissue hemorrhage with increased microvascular permeability, elevated renal tissue levels of tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO), increased serum levels of creatinine and aspartate aminotransferase (AST) and hematuria. Results Pre-ischemic treatment with the C5a Receptor (C5aR) antagonist (1 mg/kg IV or 10 mg/kg PO) substantially inhibited or prevented I/R-induced hematuria, vascular leakage, tissue levels of TNF-α and MPO, and serum levels of AST and creatinine. Histological examination of kidneys from antagonist pretreated I/R animals showed a marked reduction in tissue damage compared to drug-free I/R rats. This antagonist, however, did not inhibit complement-mediated lysis of red blood cells, suggesting unimpaired formation of the membrane attack complex (MAC). Conclusions The results demonstrate for the first time that a selective antagonist of both human and rat C5a Receptors, given either intravenously or orally, significantly protects the kidney from I/R injury in the rat. We conclude that C5a is an important pathogenic agent in renal I/R injury, and that C5a Receptor antagonists may be useful therapeutic agents for the pretreatment of anticipated renal reperfusion injury in humans.
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A new small molecule C5a Receptor antagonist inhibits the reverse-passive Arthus reaction and endotoxic shock in rats.
Journal of immunology (Baltimore Md. : 1950), 2000Co-Authors: Anna J. Strachan, David P. Fairlie, Trent M. Woodruff, Gerald Haaima, Stephen M. TaylorAbstract:C5a is implicated as a pathogenic factor in a wide range of immunoinflammatory diseases, including sepsis and immune complex disease. Agents that antagonize the effects of C5a could be useful in these diseases. We have developed some novel C5a antagonists and have determined the acute anti-inflammatory properties of a new small molecule C5a Receptor antagonist against C5a- and LPS-induced neutrophil adhesion and cytokine expression, as well as against some hallmarks of the reverse Arthus reaction in rats. We found that a single i.v. dose (1 mg/kg) of this antagonist inhibited both C5a- and LPS-induced neutropenia and elevated levels of circulating TNF-α, as well as polymorphonuclear leukocyte migration, increased TNF-α levels and vascular leakage at the site of immune complex deposition. These results indicate potent anti-inflammatory activities of a new C5a Receptor antagonist and provide more evidence for a key early role for C5a in sepsis and the reverse Arthus reaction. The results support a role for antagonists of C5a Receptors in the therapeutic intervention of immunoinflammatory disease states such as sepsis and immune complex disease.
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Effects of a new C5a Receptor antagonist on C5a- and endotoxin-induced neutropenia in the rat.
British journal of pharmacology, 1999Co-Authors: Anna J Short, Ian A. Shiels, David P. Fairlie, Allan Wong, Angela M. Finch, Gerald Haaima, Stephen M. TaylorAbstract:A new C5a Receptor antagonist, the cyclic peptide Phe-[Orn-Pro-D-cyclohexylalanine-Trp-Arg], (F-[OPdChaWR]), was tested for its ability to antagonize the neutropenic effects of both C5a and endotoxin in rats. Human recombinant C5a (2 microg kg(-1) i.v.) caused rapid neutropenia, characterized by an 83% decrease in circulating polymorphonuclear leukocytes (PMNs) at 5 min. Administration of F-[OPdChaWR] (0.3-3 mg kg(-1) i.v.), did not affect the levels of circulating PMNs but, when given 10 min prior to C5a, it inhibited the C5a-induced neutropenia by up to 70%. Administration of E. Coli lipopolysaccharide (LPS, 1 mg kg(-1) i.v.) also caused neutropenia with an 88% decrease in circulating PMNs after 30 min. When rats were pretreated with F-[OPdChaWR] (0.3 - 10 mg kg(-1) i.v.) 10 min prior to LPS, there was a dose-dependent antagonism of the neutropenia caused by LPS, with up to 69% reversal of neutropenia observed 30 min after LPS administration. These findings suggest that C5a Receptor antagonists may have therapeutic potential in the many diseases known to involve either endotoxin or C5a.
Trent M. Woodruff - One of the best experts on this subject based on the ideXlab platform.
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inhibiting the c5 C5a Receptor axis
Molecular Immunology, 2011Co-Authors: Trent M. Woodruff, Kutty Selva Nandakumar, Francesco TedescoAbstract:Abstract Activation of the complement system is a major pathogenic event that drives various inflammatory responses in numerous diseases. All pathways of complement activation lead to cleavage of the C5 molecule generating the anaphylatoxin C5a and, C5b that subsequently forms the terminal complement complex (C5b-9). C5a exerts a predominant pro-inflammatory activity through interactions with the classical G-protein coupled Receptor C5aR (CD88) as well as with the non-G protein coupled Receptor C5L2 (GPR77), expressed on various immune and non-immune cells. C5b-9 causes cytolysis through the formation of the membrane attack complex (MAC), and sub-lytic MAC and soluble C5b-9 also possess a multitude of non-cytolytic immune functions. These two complement effectors, C5a and C5b-9, generated from C5 cleavage, are key components of the complement system responsible for propagating and/or initiating pathology in different diseases, including paroxysmal nocturnal hemoglobinuria, rheumatoid arthritis, ischemia–reperfusion injuries and neurodegenerative diseases. Thus, the C5–C5a Receptor axis represents an attractive target for drug development. This review provides a comprehensive analysis of different methods of inhibiting the generation of C5a and C5b-9 as well as the signalling cascade of C5a via its Receptors. These include the inhibition of C5 cleavage through targeting of C5 convertases or via the C5 molecule itself, as well as blocking the activity of C5a by neutralizing antibodies and pharmacological inhibitors, or by targeting C5a Receptors per se . Examples of drugs and naturally occurring compounds used are discussed in relation to disease models and clinical trials. To date, only one such compound has thus far made it to clinical medicine: the anti-C5 antibody eculizumab, for treating paroxysmal nocturnal hemoglobinuria. However, a number of drug candidates are rapidly emerging that are currently in early-phase clinical trials. The C5–C5a axis as a target for drug development is highly promising for the treatment of currently intractable major human diseases.
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Oral treatment with complement factor C5a Receptor (CD88) antagonists inhibits experimental periodontitis in rats.
Journal of periodontal research, 2011Co-Authors: Torbjørn Breivik, Stephen M. Taylor, Yngvar Gundersen, Per Gjermo, Trent M. Woodruff, P. K. OpstadAbstract:Background and Objective: The complement activation product 5a (C5a) is a potent mediator of the innate immune response to infection, and may thus also importantly determine the development of periodontitis. The present study was designed to explore the effect of several novel, potent and orally active C5a Receptor (CD88) antagonists (C5aRAs) on the development of ligature-induced periodontitis in an animal model.
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Inhibiting the C5–C5a Receptor axis
Molecular immunology, 2011Co-Authors: Trent M. Woodruff, Kutty Selva Nandakumar, Francesco TedescoAbstract:Abstract Activation of the complement system is a major pathogenic event that drives various inflammatory responses in numerous diseases. All pathways of complement activation lead to cleavage of the C5 molecule generating the anaphylatoxin C5a and, C5b that subsequently forms the terminal complement complex (C5b-9). C5a exerts a predominant pro-inflammatory activity through interactions with the classical G-protein coupled Receptor C5aR (CD88) as well as with the non-G protein coupled Receptor C5L2 (GPR77), expressed on various immune and non-immune cells. C5b-9 causes cytolysis through the formation of the membrane attack complex (MAC), and sub-lytic MAC and soluble C5b-9 also possess a multitude of non-cytolytic immune functions. These two complement effectors, C5a and C5b-9, generated from C5 cleavage, are key components of the complement system responsible for propagating and/or initiating pathology in different diseases, including paroxysmal nocturnal hemoglobinuria, rheumatoid arthritis, ischemia–reperfusion injuries and neurodegenerative diseases. Thus, the C5–C5a Receptor axis represents an attractive target for drug development. This review provides a comprehensive analysis of different methods of inhibiting the generation of C5a and C5b-9 as well as the signalling cascade of C5a via its Receptors. These include the inhibition of C5 cleavage through targeting of C5 convertases or via the C5 molecule itself, as well as blocking the activity of C5a by neutralizing antibodies and pharmacological inhibitors, or by targeting C5a Receptors per se . Examples of drugs and naturally occurring compounds used are discussed in relation to disease models and clinical trials. To date, only one such compound has thus far made it to clinical medicine: the anti-C5 antibody eculizumab, for treating paroxysmal nocturnal hemoglobinuria. However, a number of drug candidates are rapidly emerging that are currently in early-phase clinical trials. The C5–C5a axis as a target for drug development is highly promising for the treatment of currently intractable major human diseases.
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role of complement C5a in mechanical inflammatory hypernociception potential use of C5a Receptor antagonists to control inflammatory pain
British Journal of Pharmacology, 2008Co-Authors: E Ting, Stephen M. Taylor, Trent M. Woodruff, Ana Tereza Gomes Guerrero, Thiago M Cunha, Waldiceu A Verri, Fernando Q Cunha, S H FerreiraAbstract:Background and purpose: C5a, a complement activation product, exhibits a broad spectrum of inflammatory activities particularly neutrophil chemoattraction. Herein, the role of C5a in the genesis of inflammatory hypernociception was investigated in rats and mice using the specific C5a Receptor antagonist PMX53 (AcF-[OP(D-Cha)WR]). Experimental approach: Mechanical hypernociception was evaluated with a modification of the Randall–Selitto test in rats and electronic pressure meter paw test in mice. Cytokines were measured by ELISA and neutrophil migration was determined by myeloperoxidase activity. Key results: Local pretreatment of rats with PMX53 (60–180 μg per paw) inhibited zymosan-, carrageenan-, lipopolysaccharide (LPS)- and antigen-induced hypernociception. These effects were associated with C5a Receptor blockade since PMX53 also inhibited the hypernociception induced by zymosan-activated serum and C5a but not by the direct-acting hypernociceptive mediators, prostaglandin E2 and dopamine. Underlying the C5a hypernociceptive mechanisms, PMX53 did not alter the cytokine release induced by inflammatory stimuli. However, PMX53 inhibited cytokine-induced hypernociception. PMX53 also inhibited the recruitment of neutrophils induced by zymosan but not by carrageenan or LPS, indicating an involvement of neutrophils in the hypernociceptive effect of C5a. Furthermore, the C5a-induced hypernociception was reduced in neutrophil-depleted rats. Extending these findings in rats, blocking C5a Receptors also reduced zymosan-induced joint hypernociception in mice. Conclusions and implications: These results suggest that C5a is an important inflammatory hypernociceptive mediator, acting by a mechanism independent of hypernociceptive cytokine release, but dependent on the presence of neutrophils. Therefore, we suggest that inhibiting the action of C5a has therapeutic potential in the control of inflammatory pain. British Journal of Pharmacology (2008) 153, 1043–1053; doi:10.1038/sj.bjp.0707640; published online 17 December 2007
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Therapeutic activity of C5a Receptor antagonists in a rat model of neurodegeneration
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2006Co-Authors: Trent M. Woodruff, Ian A. Shiels, James W. Crane, Lavinia M. Proctor, Kathryn M. Buller, Annie B. Shek, Kurt J. De Vos, Sandra Pollitt, Hua M. Williams, Peter N. MonkAbstract:The complement system is thought to be involved in the pathogenesis of numerous neurological diseases, although its precise role remains controversial. In this study we used orally active C5a Receptor antagonists (PMX53 and PMX205) developed in our laboratories in a rat model of 3-nitropropionic acid (3-NP) -induced Huntington’s disease. Administration of the C5a antagonists (10 mg/kg/day, oral) either 48 h pre- or 48 h post-toxin significantly reduced body weight loss, anorexia, and behavioral and motor deficits associated with 3-NP intoxication. Striatal lesion size, apoptosis, neutrophil infiltration, and hemorrhage were also significantly reduced in C5a antagonist-treated rats. Immunohistochemical analysis demonstrated marked deposition of C3 and C9, and up-regulation of C5a Receptors on neuronal cells at the time of lesion formation. Inhibition of prostaglandins or TNF-α with ibuprofen or infliximab had no effect in this model. The C5a antagonists did not affect 3-NP-induced cell death when added dir...
