Shiga Toxin/Lipopolysaccharide Activates Caspase-4 and Gasdermin D to Trigger Mitochondrial Reactive Oxygen Species Upstream of the NLRP3 Inflammasome
Jaye M. Platnich,
Hyunjae Chung,
Arthur Lau,
Christina F. Sandall,
Adom Bondzi-Simpson,
Huey-Miin Chen,
Takanori Komada,
Aaron C. Trotman-Grant,
Jeremy R. Brandelli,
Justin Chun,
Paul L. Beck,
Dana J. Philpott,
Stephen E. Girardin,
May Ho,
Roger P. Johnson,
Justin A. MacDonald,
Glen D. Armstrong,
Daniel A. Muruve
Affiliations
Jaye M. Platnich
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Hyunjae Chung
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Arthur Lau
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Christina F. Sandall
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
Adom Bondzi-Simpson
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Huey-Miin Chen
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
Takanori Komada
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Aaron C. Trotman-Grant
Department of Immunology, University of Toronto, Toronto, ON, Canada
Jeremy R. Brandelli
Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Justin Chun
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Paul L. Beck
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Dana J. Philpott
Department of Immunology, University of Toronto, Toronto, ON, Canada
Stephen E. Girardin
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
May Ho
Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Roger P. Johnson
Public Health Agency of Canada, National Microbiology Laboratory, Guelph, ON, Canada
Justin A. MacDonald
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
Glen D. Armstrong
Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
Daniel A. Muruve
Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada; Corresponding author
Summary: The non-canonical caspase-4 and canonical NLRP3 inflammasomes are both activated by intracellular lipopolysaccharide (LPS), but the crosstalk between these two pathways remains unclear. Shiga toxin 2 (Stx2)/LPS complex, from pathogenic enterohemorrhagic Escherichia coli, activates caspase-4, gasdermin D (GSDMD), and the NLRP3 inflammasome in human THP-1 macrophages, but not mouse macrophages that lack the Stx receptor CD77. Stx2/LPS-mediated IL-1β secretion and pyroptosis are dependent on mitochondrial reactive oxygen species (ROS) downstream of the non-canonical caspase-4 inflammasome and cleaved GSDMD, which is enriched at the mitochondria. Blockade of caspase-4 activation and ROS generation as well as GSDMD deficiency significantly reduces Stx2/LPS-induced IL-1β production and pyroptosis. The NLRP3 inflammasome plays a significant role in amplifying Stx2/LPS-induced GSDMD cleavage and pyroptosis, with significant reduction of these responses in NLRP3-deficient THP-1 cells. Together, these data show that Stx2/LPS complex activates the non-canonical inflammasome and mitochondrial ROS upstream of the NLRP3 inflammasome to promote cytokine maturation and pyroptosis. : Shiga toxin 2 is a major virulence factor of enterohemorrhagic E. coli. Platnich et al. show that Shiga toxin 2 and co-transported lipopolysaccharide activate caspase-4, gasdermin D, and mitochondrial ROS upstream of the NLRP3 inflammasome in macrophages. Inflammasome activation may play a role in the pathogenesis of enterohemorrhagic E. coli infection and disease. Keywords: Shiga toxin, inflammasome, NLRP3, caspase-4, gasdermin D, enterohemorrhagic Escherichia coli, macrophages
