Microbiota Normalization Reveals that Canonical Caspase-1 Activation Exacerbates Chemically Induced Intestinal Inflammation

Abstract

Inflammasomes play a central role in regulating intestinal barrier function and immunity during steady state and disease. Because the discoveries of a passenger mutation and a colitogenic microbiota in the widely used caspase-1-deficient mouse strain have cast doubt on previously identified direct functions of caspase-1, we reassessed the role of caspase-1 in the intestine. To this end, we generated Casp1−/− and Casp11−/− mice and rederived them into an enhanced barrier facility to standardize the microbiota. We found that caspase-11 does not influence caspase-1-dependent processing of IL-18 in homeostasis and during DSS colitis. Deficiency of caspase-1, but not caspase-11, ameliorated the severity of DSS colitis independent of microbiota composition. Ablation of caspase-1 in intestinal epithelial cells was sufficient to protect mice against DSS colitis. Moreover, Casp1−/− mice developed fewer inflammation-induced intestinal tumors than control mice. These data show that canonical inflammasome activation controls caspase-1 activity, contributing to exacerbation of chemical-induced colitis.

Keywords

• caspase-1
• caspase-11
• colitis
• inflammasome
• microbiota
• colon
• intestine
• DSS
• inflammation-induced tumorigenesis