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Nitric oxide regulates T cell responses
S8
Abstracts / Nitric Oxide 27 (2012) S2–S50
coordination, NO reacts with superoxide, lipid radicals and can be further oxidized by metalloproteins to yield reactive secondary species. These products include peroxynitrite and nitrogen dioxide that expand the breadth of reactions that transduce redox-dependent signaling. One class of reactive species byproducts, electrophilic unsaturated fatty acids, induce PTPM by reacting with protein thiols and other nucleophilic amino acids. Notably, multiple transcriptional regulatory mechanisms have protein constituents with functionally-significant electrophile-reactive amino acids. This highly conserved property provides cells with a capability to undergo stress-related adaptive signaling reactions. We present new data regarding the mechanisms of formation of electrophilic nitro- and keto-fatty acid derivatives and how to detect these reactive species and the PTPM they induce. The molecular targets, acute signaling responses, transcriptional regulation, cell signaling responses and physiological actions that are induced by low concentrations of electrophilic fatty acids are anti-inflammatory in nature. In aggregate, this presentation will advance the concept that NO and lipid electrophile-mediated PTPM reactions link cell function with inflammatory and metabolic status. http://dx.doi.org/10.1016/j.niox.2012.04.029
Session: NO and immunology/inflammation IS-20 Nitric oxide regulates T cell responses Eddy Foo Y. Liew Division of Immunology, Infection and Inflammation, University of Glasgow, Glasgow G12 8TA, UK We reveal a previously unrecognized subset of CD4+CD25+ Tregs derived from CD4+CD25 T cells induced by nitric oxide (NO). The induction of Tregs (NO-Tregs) is independent of cGMP but dependent on p53, IL-2 and OX40. NO-Tregs suppressed the proliferation of CD4+CD25 T cells in vitro and attenuated colitis and collageninduced arthritis in vivo in an IL-10-dependent manner. NO-Tregs were also induced in vivo in SCID mice adaptively transferred with CD4+CD25 T cells in the presence of LPS and IFN c and the induction was completely inhibited by L-NMMA. We also found that NO-Treg preferentially suppresses the polarization and established Th17 but not Th1 cells and attenuates experimental autoimmune encephalomyelitis (EAE). Furthermore NO can directly suppress the polarization of Th17 cells. In contrast NO can switch CD4+ T cells from a Th17 phenotype to that of Th9 phenotype and exacerbates experimental airway hypersensitivity. The molecular mechanism and the function of NO in modulating T cells will be discussed. http://dx.doi.org/10.1016/j.niox.2012.04.030
IS-21 RONS in inflammatory neurodegeneration Guy C. Brown Department of Biochemistry, University of Cambridge, CB2 1QW, UK Inflammatory neurodegeneration is neuronal degeneration due to inflammation, and is thought to contribute to neuronal loss in infectious, ischemic, traumatic and neurodegenerative brain pathologies. We have identified three mechanisms by which inflamed glia kill neurons: iNOS, PHOX and phagocytosis. Inflamed microglia (brain macrophages) and astrocytes express inducible nitric oxide synthase (iNOS), producing high levels of NO,
which inhibits mitochondrial respiration at cytochrome oxidase in competition with oxygen, sensitising neurons to hypoxic death. In addition, NO-derivatives peroxynitrite and S-nitrosothiols inactivate mitochondrial complex I, stimulating oxidant production by mitochondria. The phagocyte NADPH oxidase (PHOX) is constitutively expressed by microglia, and we find that H2O2 from PHOX activation is required for inflammatory activation of microglia. Alternatively, superoxide from PHOX can react with NO from iNOS to produce peroxynitrite that induces reversible phosphatidyserine (PS) exposure on neurons, which induces microglia to phagocytose viable neurons. We found inflammatory activation of neuronal-glial co-cultures with LPS, LTA, TNF-aor a-amyloid, or in vivo with LPS results, in progressive loss of neurons, accompanied by microglial phagocytosis of neurons, and is prevented by blocking phagocytosis or knockout of PS-binding adaptor protein MFG-E8. Cell death by primary phagocytosis may constitute a novel form of cell death: ‘phagoptosis’. References M. Fricker, J.J. Neher, J.W. Zhao, C. Théry, A.M. Tolkovsky, G.C. Brown, MFG-E8 mediates primary phagocytosis of viable neurons during neuroinflammation. J Neurosci. 32 (2012) 2657–2666. J.J. Neher, U. Neniskyte, Z.W. Zhao, A. Bal-Price, A.M. Tolkovsky, G.C. Brown, Inhibition of microglial phagocytosis is sufficient to prevent inflammatory neuronal death. J. Immunol. 186 (2011) 4973–4983. G.C. Brown, J.J. Neher, Inflammatory neurodegeneration and mechanisms of microglial killing of neurons. Mol. Neurobiol. 41 (2010) 242–247. G.C. Brown, Nitric oxide and neuronal death. Nitric Oxide 23 (2010) 153–165.
http://dx.doi.org/10.1016/j.niox.2012.04.031
IS-22 Regulated release of nitric oxide by nonhematopoietic stroma controls expansion of the activated T cell pool in lymph nodes Veronika Lukacs-Kornek a, Deepali Malhotra a,b, Shannon J. Turley a,c a Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Boston Massachusetts, USA, b Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA, c Department of Microbiology and Immunobiology, Harvard Medical School, Boston Massachusetts, USA Fibroblastic reticular cells (FRCs) and lymphatic endothelial cells (LECs) are non-hematopoietic stromal cells of lymphoid organs. They influence the migration and homeostasis of naïve T cells; however, their influence on activated T cells remains undescribed. We have recently identified that FRCs and LECs inhibited T cell proliferation through regulated nitric oxide synthase-2(NOS2)-dependent mechanism. Importantly, in vivo NOS2 expression by FRCs and LECs controlled the size of the activated T cell pool. Mechanistically, the expression of NOS2 and production of nitric oxide (NO) paralleled the activation of T cells and required IFNGR1 signaling in FRCs and LECs, and was augmented by TNF and direct contact with activated T cells. Comparative transcriptomic analysis revealed that various adhesion molecules and multiple components of cytokine, complement and JAK-STAT signaling pathways are upregulated in FRCs in the presence of activated T cells. Based on these data, current efforts aim to identify the molecules involved in the direct stromal cell-T cell interaction influencing NO production by FRCs. This negative regulatory feedback mechanism is likely of great relevance to regulation of immune responses either to prevent excessive T cell expansion or to avoid structural damage within LNs caused by the expanding T cell pool. http://dx.doi.org/10.1016/j.niox.2012.04.032
Abstracts / Nitric Oxide 27 (2012) S2–S50
coordination, NO reacts with superoxide, lipid radicals and can be further oxidized by metalloproteins to yield reactive secondary species. These products include peroxynitrite and nitrogen dioxide that expand the breadth of reactions that transduce redox-dependent signaling. One class of reactive species byproducts, electrophilic unsaturated fatty acids, induce PTPM by reacting with protein thiols and other nucleophilic amino acids. Notably, multiple transcriptional regulatory mechanisms have protein constituents with functionally-significant electrophile-reactive amino acids. This highly conserved property provides cells with a capability to undergo stress-related adaptive signaling reactions. We present new data regarding the mechanisms of formation of electrophilic nitro- and keto-fatty acid derivatives and how to detect these reactive species and the PTPM they induce. The molecular targets, acute signaling responses, transcriptional regulation, cell signaling responses and physiological actions that are induced by low concentrations of electrophilic fatty acids are anti-inflammatory in nature. In aggregate, this presentation will advance the concept that NO and lipid electrophile-mediated PTPM reactions link cell function with inflammatory and metabolic status. http://dx.doi.org/10.1016/j.niox.2012.04.029
Session: NO and immunology/inflammation IS-20 Nitric oxide regulates T cell responses Eddy Foo Y. Liew Division of Immunology, Infection and Inflammation, University of Glasgow, Glasgow G12 8TA, UK We reveal a previously unrecognized subset of CD4+CD25+ Tregs derived from CD4+CD25 T cells induced by nitric oxide (NO). The induction of Tregs (NO-Tregs) is independent of cGMP but dependent on p53, IL-2 and OX40. NO-Tregs suppressed the proliferation of CD4+CD25 T cells in vitro and attenuated colitis and collageninduced arthritis in vivo in an IL-10-dependent manner. NO-Tregs were also induced in vivo in SCID mice adaptively transferred with CD4+CD25 T cells in the presence of LPS and IFN c and the induction was completely inhibited by L-NMMA. We also found that NO-Treg preferentially suppresses the polarization and established Th17 but not Th1 cells and attenuates experimental autoimmune encephalomyelitis (EAE). Furthermore NO can directly suppress the polarization of Th17 cells. In contrast NO can switch CD4+ T cells from a Th17 phenotype to that of Th9 phenotype and exacerbates experimental airway hypersensitivity. The molecular mechanism and the function of NO in modulating T cells will be discussed. http://dx.doi.org/10.1016/j.niox.2012.04.030
IS-21 RONS in inflammatory neurodegeneration Guy C. Brown Department of Biochemistry, University of Cambridge, CB2 1QW, UK Inflammatory neurodegeneration is neuronal degeneration due to inflammation, and is thought to contribute to neuronal loss in infectious, ischemic, traumatic and neurodegenerative brain pathologies. We have identified three mechanisms by which inflamed glia kill neurons: iNOS, PHOX and phagocytosis. Inflamed microglia (brain macrophages) and astrocytes express inducible nitric oxide synthase (iNOS), producing high levels of NO,
which inhibits mitochondrial respiration at cytochrome oxidase in competition with oxygen, sensitising neurons to hypoxic death. In addition, NO-derivatives peroxynitrite and S-nitrosothiols inactivate mitochondrial complex I, stimulating oxidant production by mitochondria. The phagocyte NADPH oxidase (PHOX) is constitutively expressed by microglia, and we find that H2O2 from PHOX activation is required for inflammatory activation of microglia. Alternatively, superoxide from PHOX can react with NO from iNOS to produce peroxynitrite that induces reversible phosphatidyserine (PS) exposure on neurons, which induces microglia to phagocytose viable neurons. We found inflammatory activation of neuronal-glial co-cultures with LPS, LTA, TNF-aor a-amyloid, or in vivo with LPS results, in progressive loss of neurons, accompanied by microglial phagocytosis of neurons, and is prevented by blocking phagocytosis or knockout of PS-binding adaptor protein MFG-E8. Cell death by primary phagocytosis may constitute a novel form of cell death: ‘phagoptosis’. References M. Fricker, J.J. Neher, J.W. Zhao, C. Théry, A.M. Tolkovsky, G.C. Brown, MFG-E8 mediates primary phagocytosis of viable neurons during neuroinflammation. J Neurosci. 32 (2012) 2657–2666. J.J. Neher, U. Neniskyte, Z.W. Zhao, A. Bal-Price, A.M. Tolkovsky, G.C. Brown, Inhibition of microglial phagocytosis is sufficient to prevent inflammatory neuronal death. J. Immunol. 186 (2011) 4973–4983. G.C. Brown, J.J. Neher, Inflammatory neurodegeneration and mechanisms of microglial killing of neurons. Mol. Neurobiol. 41 (2010) 242–247. G.C. Brown, Nitric oxide and neuronal death. Nitric Oxide 23 (2010) 153–165.
http://dx.doi.org/10.1016/j.niox.2012.04.031
IS-22 Regulated release of nitric oxide by nonhematopoietic stroma controls expansion of the activated T cell pool in lymph nodes Veronika Lukacs-Kornek a, Deepali Malhotra a,b, Shannon J. Turley a,c a Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Boston Massachusetts, USA, b Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA, c Department of Microbiology and Immunobiology, Harvard Medical School, Boston Massachusetts, USA Fibroblastic reticular cells (FRCs) and lymphatic endothelial cells (LECs) are non-hematopoietic stromal cells of lymphoid organs. They influence the migration and homeostasis of naïve T cells; however, their influence on activated T cells remains undescribed. We have recently identified that FRCs and LECs inhibited T cell proliferation through regulated nitric oxide synthase-2(NOS2)-dependent mechanism. Importantly, in vivo NOS2 expression by FRCs and LECs controlled the size of the activated T cell pool. Mechanistically, the expression of NOS2 and production of nitric oxide (NO) paralleled the activation of T cells and required IFNGR1 signaling in FRCs and LECs, and was augmented by TNF and direct contact with activated T cells. Comparative transcriptomic analysis revealed that various adhesion molecules and multiple components of cytokine, complement and JAK-STAT signaling pathways are upregulated in FRCs in the presence of activated T cells. Based on these data, current efforts aim to identify the molecules involved in the direct stromal cell-T cell interaction influencing NO production by FRCs. This negative regulatory feedback mechanism is likely of great relevance to regulation of immune responses either to prevent excessive T cell expansion or to avoid structural damage within LNs caused by the expanding T cell pool. http://dx.doi.org/10.1016/j.niox.2012.04.032