Macrophages mediate innate immune responses that recognise foreign pathogens and bacterial lipopo... more Macrophages mediate innate immune responses that recognise foreign pathogens and bacterial lipopolysaccharide (LPS) recruits a signalling pathway through Toll like receptor 4 (TLR4) to induce pro-inflammatory cytokines and reactive oxygen species (ROS). LPS activation also skews the metabolism of macrophages towards a glycolytic phenotype. Here we demonstrate that the LPS triggered glycolytic switch is significantly attenuated in GSTO1-1 deficient macrophages. In response to LPS, GSTO1-1 deficient macrophages do not produce excess lactate, or dephosphorylate AMPK, a key metabolic stress regulator. In addition, GSTO1-1 deficient cells don't induce HIF1α that plays a key role in maintaining the pro-inflammatory state of activated macrophages. The accumulation of TCA cycle intermediates succinate and fumarate that occurs in LPS treated macrophages was also blocked in GSTO1-1 deficient cells. These data indicate that GSTO1-1 is required for LPS mediated signalling in macrophages and...
Journal of immunology (Baltimore, Md. : 1950), 2015
Activation of the noncanonical inflammasome, mediated by caspase-11, serves as an additional path... more Activation of the noncanonical inflammasome, mediated by caspase-11, serves as an additional pathway for the production of the proinflammatory cytokines IL-1β and IL-18. Noncanonical inflammasome activity occurs during host defense against Gram-negative bacteria and in models of acute septic shock. We propose that the noncanonical inflammasome is activated in mice during acute intestinal inflammation elicited by dextran sodium sulfate (DSS), a model of experimental colitis. We find that caspase-11(-/-) mice display enhanced susceptibility to DSS, because of impaired IL-18 production. The impaired IL-18 levels observed are shown to result in reduced intestinal epithelial cell proliferation and increased cell death. We also suggest that a novel type II IFN-dependent, type I IFN-TRIF-independent signaling pathway is required for in vivo caspase-11 production in intestinal epithelial cells during DSS colitis. Collectively, these data suggest that IFN-γ-mediated caspase-11 expression has...
Bacterial lipopolysaccharide (LPS) stimulation of macrophages and inflammation via the Toll-like ... more Bacterial lipopolysaccharide (LPS) stimulation of macrophages and inflammation via the Toll-like receptor 4 (TLR4) signaling pathway through NF-κΒ generates reactive oxygen species (ROS) and proinflammatory cytokines such as IL-1β, IL-6, and TNFα. Because glutathione transferase Omega 1-1 (GSTO1-1) can catalyze redox reactions such as the deglutathionylation of proteins and has also been implicated in the release of IL-1β we investigated its role in the development of LPS-mediated inflammation. Our data show that shRNA knockdown of GSTO1-1 in macrophage-like J774.1A cells blocks the expression of NADPH oxidase 1 and the generation of ROS after LPS stimulation. Similar results were obtained with a GSTO1-1 inhibitor. To maintain high ROS levels during an inflammatory response, LPS stimulation causes the suppression of enzymes such as catalase and glutathione peroxidase that protect against oxidative stress. The knockdown of GSTO1-1 also attenuates this response. Our data indicate that...
Macrophages mediate innate immune responses that recognise foreign pathogens and bacterial lipopo... more Macrophages mediate innate immune responses that recognise foreign pathogens and bacterial lipopolysaccharide (LPS) recruits a signalling pathway through Toll like receptor 4 (TLR4) to induce pro-inflammatory cytokines and reactive oxygen species (ROS). LPS activation also skews the metabolism of macrophages towards a glycolytic phenotype. Here we demonstrate that the LPS triggered glycolytic switch is significantly attenuated in GSTO1-1 deficient macrophages. In response to LPS, GSTO1-1 deficient macrophages do not produce excess lactate, or dephosphorylate AMPK, a key metabolic stress regulator. In addition, GSTO1-1 deficient cells don't induce HIF1α that plays a key role in maintaining the pro-inflammatory state of activated macrophages. The accumulation of TCA cycle intermediates succinate and fumarate that occurs in LPS treated macrophages was also blocked in GSTO1-1 deficient cells. These data indicate that GSTO1-1 is required for LPS mediated signalling in macrophages and...
Journal of immunology (Baltimore, Md. : 1950), 2015
Activation of the noncanonical inflammasome, mediated by caspase-11, serves as an additional path... more Activation of the noncanonical inflammasome, mediated by caspase-11, serves as an additional pathway for the production of the proinflammatory cytokines IL-1β and IL-18. Noncanonical inflammasome activity occurs during host defense against Gram-negative bacteria and in models of acute septic shock. We propose that the noncanonical inflammasome is activated in mice during acute intestinal inflammation elicited by dextran sodium sulfate (DSS), a model of experimental colitis. We find that caspase-11(-/-) mice display enhanced susceptibility to DSS, because of impaired IL-18 production. The impaired IL-18 levels observed are shown to result in reduced intestinal epithelial cell proliferation and increased cell death. We also suggest that a novel type II IFN-dependent, type I IFN-TRIF-independent signaling pathway is required for in vivo caspase-11 production in intestinal epithelial cells during DSS colitis. Collectively, these data suggest that IFN-γ-mediated caspase-11 expression has...
Bacterial lipopolysaccharide (LPS) stimulation of macrophages and inflammation via the Toll-like ... more Bacterial lipopolysaccharide (LPS) stimulation of macrophages and inflammation via the Toll-like receptor 4 (TLR4) signaling pathway through NF-κΒ generates reactive oxygen species (ROS) and proinflammatory cytokines such as IL-1β, IL-6, and TNFα. Because glutathione transferase Omega 1-1 (GSTO1-1) can catalyze redox reactions such as the deglutathionylation of proteins and has also been implicated in the release of IL-1β we investigated its role in the development of LPS-mediated inflammation. Our data show that shRNA knockdown of GSTO1-1 in macrophage-like J774.1A cells blocks the expression of NADPH oxidase 1 and the generation of ROS after LPS stimulation. Similar results were obtained with a GSTO1-1 inhibitor. To maintain high ROS levels during an inflammatory response, LPS stimulation causes the suppression of enzymes such as catalase and glutathione peroxidase that protect against oxidative stress. The knockdown of GSTO1-1 also attenuates this response. Our data indicate that...
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Papers by Luke O'Neill