2. Academic Validation
  3. Shiga Toxin/Lipopolysaccharide Activates Caspase-4 and Gasdermin D to Trigger Mitochondrial Reactive Oxygen Species Upstream of the NLRP3 Inflammasome

Shiga Toxin/Lipopolysaccharide Activates Caspase-4 and Gasdermin D to Trigger Mitochondrial Reactive Oxygen Species Upstream of the NLRP3 Inflammasome

  • Cell Rep. 2018 Nov 6;25(6):1525-1536.e7. doi: 10.1016/j.celrep.2018.09.071.
Jaye M Platnich 1,  Hyunjae Chung 1,  Arthur Lau 1,  Christina F Sandall 2,  Adom Bondzi-Simpson 1,  Huey-Miin Chen 2,  Takanori Komada 1,  Aaron C Trotman-Grant 3,  Jeremy R Brandelli 4,  Justin Chun 1,  Paul L Beck 1,  Dana J Philpott 3,  Stephen E Girardin 5,  May Ho 4,  Roger P Johnson 6,  Justin A MacDonald 2,  Glen D Armstrong 4,  Daniel A Muruve 7
Affiliations

Affiliations

  • 1 Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.
  • 2 Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada.
  • 3 Department of Immunology, University of Toronto, Toronto, ON, Canada.
  • 4 Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.
  • 5 Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
  • 6 Public Health Agency of Canada, National Microbiology Laboratory, Guelph, ON, Canada.
  • 7 Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada. Electronic address: [email protected].
PMID: 30404007 DOI: 10.1016/j.celrep.2018.09.071
Abstract

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.

Keywords

NLRP3; Shiga toxin; caspase-4; enterohemorrhagic Escherichia coli; gasdermin D; inflammasome; macrophages.

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