GSDMB modulates intestinal epithelial homeostasis via regulating hyperactive unfolded protein response in Crohn's disease.

Background: Impaired intestinal epithelial barrier has been considered to be associated with an increasing variety of gastrointestinal diseases, especially inflammatory bowel disease (IBD) encompassing Crohn's disease (CD) and ulcerative colitis (UC). We aimed to investigate the role of Gasdermin B (GSDMB) in modulating intestinal epithelial barrier integrity and proposed a promising therapeutic strategy.

Methods: GSDMB expression was evaluated in adult CD samples by molecular biology means and single-cell transcriptomes. We generated GSDMB (Rosa26-lsl/lsl-GSDMB;Villin-Cre) and one of its functional missense variant rs2305480 (Rosa26-lsl/lsl-GSDMB-MU;Villin-Cre) intestinal epithelial-specific knock in mice to observe the functions of GSDMB in intestinal epithelial barrier. RNA-seq analysis as well as human and murine intestine-derived organoids were used to determine the pathogenic mechanism of GSDMB.

Results: The expression of GSDMB was increased during active intestinal inflammation and principally localized in intestinal epithelial cells (IECs). Rosa26-lsl/lsl-GSDMB;Villin-Cre mice developed enterocolitis and exhibited aberrant intestinal barrier integrity. Mechanistically, epithelial GSDMB modulated hyperactive unfolded protein response of IECs by up-regulating BHLHA15 to mediate intestinal barrier injury. Rosa26-lsl/lsl-GSDMB-MU;Villin-Cre mice with the mutant rs2305480 of GSDMB aggravated such inflammatory effects.

Conclusion: We have uncovered an important and a previously unrecognized role of GSDMB in intestinal homeostasis, which represents a potential therapeutic target for intestinal inflammation.