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.
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-1β production in mφs in comparison to LPS-treated controls. When WT and ASC-/- macrophages were treated with inhibitors of caspase-1, IL-1β, or NADPH oxidase, we found that IL-1β production by caspase-1/ASC inflammasome required reactive oxygen species (ROS) as a secondary signal. Moreover, IL-1β regulated NF-κB signaling of inflammatory cytokine gene expression and, subsequently, intracellular parasite replication in macrophages. NLRP3-/- macrophages, despite an inability to elicit IL-1β 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-1β-independent manner and contributed to efficient parasite killing. We conclude that caspase-1/ASC inflammasomes play a significant role in the activation of IL-1β/ROS and NF-κB signaling of cytokine gene expression for T. cruzi control in human and mouse macrophages. However, NLRP3-mediated IL-1β/NFκB activation is dispensable and compensated for by ROS-mediated control of T. cruzi replication and survival in macrophages.
Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, Texas, United States of America.
Nilay
N
Dey
Department of BioChemistry & Molecular Biology, UTMB, Galveston, Texas, United States of America.
Mala
M
Sinha
Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, Texas, United States of America.
Shivali
S
Gupta
Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben", Ciudad Autónoma de Buenos Aires, Argentina.
Mariela Natacha
MN
Gonzalez
Department of Pathology, UTMB, Galveston, Texas, United States of America.
Rong
R
Fang
Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, Texas, United States of America.
Janice J
JJ
Endsley
Department of BioChemistry & Molecular Biology, UTMB, Galveston, Texas, United States of America.
Bruce A
BA
Luxon
Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, Texas, United States of America; Department of Pathology, UTMB, Galveston, Texas, United States of America; Faculty of the Institute for Human Infections and Immunity and the Center for Tropical Diseases, UTMB, Galveston, Texas, United States of America.
Nisha Jain
NJ
Garg
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D053468:CARD Signaling Adaptor Proteins; D002352:Carrier Proteins / Q000235:genetics; D020170:Caspase 1 / Q000378:metabolism*; D014355:Chagas Disease / Q000235:genetics / Q000378:metabolism* / Q000469:parasitology*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D058847:Inflammasomes / Q000235:genetics / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism* / Q000469:parasitology; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism*; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D014349:Trypanosoma cruzi
D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D016328:NF-kappa B; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; C402202:PYCARD protein, human; C498534:Pycard protein, mouse; D017382:Reactive Oxygen Species; D020170:Caspase 1