Clostridium difficile toxin B-induced necrosis is mediated by the host epithelial cell NADPH oxidase complex.

Farrow MA, Chumbler NM, Lapierre LA, Franklin JL, Rutherford SA, Goldenring JR, Lacy DB
Proc Natl Acad Sci U S A. 2013 110 (46): 18674-9

PMID: 24167244 · PMCID: PMC3831945 · DOI:10.1073/pnas.1313658110

Clostridium difficile infection (CDI) is a leading cause of health care-associated diarrhea and has increased in incidence and severity over the last decade. Pathogenesis is mediated by two toxins, TcdA and TcdB, which cause fluid secretion, inflammation, and necrosis of the colonic mucosa. TcdB is a potent cytotoxin capable of inducing enzyme-independent necrosis in both cells and tissue. In this study, we show that TcdB-induced cell death depends on assembly of the host epithelial cell NADPH oxidase (NOX) complex and the production of reactive oxygen species (ROS). Treating cells with siRNAs directed against key components of the NOX complex, chemical inhibitors of NOX function, or molecules that scavenge superoxide or ROS confers protection against toxin challenge. To test the hypothesis that chemical inhibition of TcdB-induced cytotoxicity can protect against TcdB-induced tissue damage, we treated colonic explants with diphenyleneiodonium (DPI), a flavoenzyme inhibitor, or N-acetylcysteine (NAC), an antioxidant. TcdB-induced ROS production in colonic tissue was inhibited with DPI, and both DPI and NAC conferred protection against TcdB-induced tissue damage. The efficacy of DPI and NAC provides proof of concept that chemical attenuation of ROS could serve as a viable strategy for protecting the colonic mucosa of patients with CDI.

MeSH Terms (16)

Bacterial Proteins Bacterial Toxins Blotting, Western Caco-2 Cells Enterotoxins HeLa Cells Humans Microscopy, Confocal Multiprotein Complexes NADPH Oxidases Necrosis Reverse Transcriptase Polymerase Chain Reaction RNA, Small Interfering RNA Interference Transfection Virulence Factors

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