Dataset Information

Caspase-1/ASC inflammasome-mediated activation of IL-1?-ROS-NF-?B pathway for control of Trypanosoma cruzi replication and survival is dispensable in NLRP3-/- macrophages.

ABSTRACT: In this study, we have utilized wild-type (WT), ASC-/-, and NLRP3-/- macrophages and inhibition approaches to investigate the mechanisms of inflammasome activation and their role in Trypanosoma cruzi infection. We also probed human macrophages and analyzed published microarray datasets from human fibroblasts, and endothelial and smooth muscle cells for T. cruzi-induced changes in the expression genes included in the RT Profiler Human Inflammasome arrays. T. cruzi infection elicited a subdued and delayed activation of inflammasome-related gene expression and IL-1? production in m?s in comparison to LPS-treated controls. When WT and ASC-/- macrophages were treated with inhibitors of caspase-1, IL-1?, or NADPH oxidase, we found that IL-1? production by caspase-1/ASC inflammasome required reactive oxygen species (ROS) as a secondary signal. Moreover, IL-1? regulated NF-?B signaling of inflammatory cytokine gene expression and, subsequently, intracellular parasite replication in macrophages. NLRP3-/- macrophages, despite an inability to elicit IL-1? activation and inflammatory cytokine gene expression, exhibited a 4-fold decline in intracellular parasites in comparison to that noted in matched WT controls. NLRP3-/- macrophages were not refractory to T. cruzi, and instead exhibited a very high basal level of ROS (>100-fold higher than WT controls) that was maintained after infection in an IL-1?-independent manner and contributed to efficient parasite killing. We conclude that caspase-1/ASC inflammasomes play a significant role in the activation of IL-1?/ROS and NF-?B signaling of cytokine gene expression for T. cruzi control in human and mouse macrophages. However, NLRP3-mediated IL-1?/NF?B activation is dispensable and compensated for by ROS-mediated control of T. cruzi replication and survival in macrophages.

SUBMITTER: Dey N

PROVIDER: S-EPMC4221042 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Caspase-1/ASC inflammasome-mediated activation of IL-1β-ROS-NF-κB pathway for control of Trypanosoma cruzi replication and survival is dispensable in NLRP3-/- macrophages.

Dey Nilay N Sinha Mala M Gupta Shivali S Gonzalez Mariela Natacha MN Fang Rong R Endsley Janice J JJ Luxon Bruce A BA Garg Nisha Jain NJ

PloS one 20141105 11

In this study, we have utilized wild-type (WT), ASC-/-, and NLRP3-/- macrophages and inhibition approaches to investigate the mechanisms of inflammasome activation and their role in Trypanosoma cruzi infection. We also probed human macrophages and analyzed published microarray datasets from human fibroblasts, and endothelial and smooth muscle cells for T. cruzi-induced changes in the expression genes included in the RT Profiler Human Inflammasome arrays. T. cruzi infection elicited a subdued and ...[more]

PMID: 25372293

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Project description:A type III secretion system (T3SS) in pathogenic Yersinia species functions to translocate Yop effectors, which modulate cytokine production and regulate cell death in macrophages. Distinct pathways of T3SS-dependent cell death and caspase-1 activation occur in Yersinia-infected macrophages. One pathway of cell death and caspase-1 activation in macrophages requires the effector YopJ. YopJ is an acetyltransferase that inactivates MAPK kinases and IKK? to cause TLR4-dependent apoptosis in naïve macrophages. A YopJ isoform in Y. pestis KIM (YopJ(KIM)) has two amino acid substitutions, F177L and K206E, not present in YopJ proteins of Y. pseudotuberculosis and Y. pestis CO92. As compared to other YopJ isoforms, YopJ(KIM) causes increased apoptosis, caspase-1 activation, and secretion of IL-1? in Yersinia-infected macrophages. The molecular basis for increased apoptosis and activation of caspase-1 by YopJ(KIM) in Yersinia-infected macrophages was studied. Site directed mutagenesis showed that the F177L and K206E substitutions in YopJ(KIM) were important for enhanced apoptosis, caspase-1 activation, and IL-1? secretion. As compared to YopJ(CO92), YopJ(KIM) displayed an enhanced capacity to inhibit phosphorylation of I?B-? in macrophages and to bind IKK? in vitro. YopJ(KIM) also showed a moderately increased ability to inhibit phosphorylation of MAPKs. Increased caspase-1 cleavage and IL-1? secretion occurred in IKK?-deficient macrophages infected with Y. pestis expressing YopJ(CO92), confirming that the NF-?B pathway can negatively regulate inflammasome activation. K+ efflux, NLRP3 and ASC were important for secretion of IL-1? in response to Y. pestis KIM infection as shown using macrophages lacking inflammasome components or by the addition of exogenous KCl. These data show that caspase-1 is activated in naïve macrophages in response to infection with a pathogen that inhibits IKK? and MAPK kinases and induces TLR4-dependent apoptosis. This pro-inflammatory form of apoptosis may represent an early innate immune response to highly virulent pathogens such as Y. pestis KIM that have evolved an enhanced ability to inhibit host signaling pathways.

Project description:Propofol infusion syndrome (PRIS) is an uncommon life-threatening complication observed most often in patients receiving high-dose propofol. High-dose propofol treatment with a prolonged duration can damage the immune system. However, the associated molecular mechanisms remain unclear. An increasing number of clinical and experimental observations have demonstrated that tissue-resident macrophages play a critical role in immune regulation during anaesthesia and procedural sedation. Since the inflammatory response is essential for mediating propofol-induced cell death and proinflammatory reactions, we hypothesised that propofol overdose induces macrophage pyroptosis through inflammasomes. Using primary cultured bone marrow-derived macrophages, murine macrophage cell lines (RAW264.7, RAW-asc and J774) and a mouse model, we investigated the role of NLRP3 inflammasome activation and secondary pyroptosis in propofol-induced cell death. We found that high-dose propofol strongly cleaved caspase-1 but not caspase-11 and biosynthesis of downstream interleukin (IL)-1β and IL-18. Inhibition of caspase-1 activity blocks IL-1β production. Moreover, NLRP3 deletion moderately suppressed cleaved caspase-1 as well as the proportion of pyroptosis, while levels of AIM2 were increased, triggering a compensatory pathway to pyroptosis in NLRP3-/- macrophages. Here, we show that propofol-induced mitochondrial reactive oxygen species (ROS) can trigger NLRP3 inflammasome activation. Furthermore, apoptosis-associated speck-like protein (ASC) was found to mediate NLRP3 and AIM2 signalling and contribute to propofol-induced macrophage pyroptosis. In addition, our work shows that propofol-induced apoptotic initiator caspase (caspase-9) subsequently cleaved effector caspases (caspase-3 and 7), indicating that both apoptotic and pyroptotic cellular death pathways are activated after propofol exposure. Our studies suggest, for the first time, that propofol-induced pyroptosis might be restricted to macrophage through an NLRP3/ASC/caspase-1 pathway, which provides potential targets for limiting adverse reactions during propofol application. These findings demonstrate that propofol overdose can trigger cell death through caspase-1 activation and offer new insights into the use of anaesthetic drugs.

Dataset Information

Caspase-1/ASC inflammasome-mediated activation of IL-1?-ROS-NF-?B pathway for control of Trypanosoma cruzi replication and survival is dispensable in NLRP3-/- macrophages.

Publications

Caspase-1/ASC inflammasome-mediated activation of IL-1β-ROS-NF-κB pathway for control of Trypanosoma cruzi replication and survival is dispensable in NLRP3-/- macrophages.

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