Epithelial Duox2 Drives Chronic Colitis-Associated Fibrosis via the NLRP3-IL-33-Mast Cell Axis.

Abstract

Introduction: Intestinal fibrosis is a common and serious complication of chronic inflammatory bowel disease (IBD) associated with stricture and obstruction. Although oxidative stress has been associated with IBD, how Duox2, the major source of ROS in gut epithelium, promotes fibrosis remains unknown. The goal of our study is to determine the role of Duox2 in IBD fibrosis.

Methods: GEO datasets were analyzed using bioinformatics to find the main pathogenic factors. AOM/DSS-induced chronic colitis mouse model was established to assess fibrosis and Duox2 expression. Adeno-associated virus (AAV)-shRNA was employed to block Duox2 in vivo. In vitro, the potential signaling pathways were further explored by molecular and cell functional analyses.

Results: RNA sequencing combined with in vivo validation showed that Duox2 is markedly upregulated in the colonic epithelium of mice with chronic colitis and fibrosis. The in vivo knockdown of Duox2 mitigated the colonic shortening and decreased collagen content, fibrosis markers, and MDA levels. Epithelial Duox2 upregulation induced NLRP3 inflammasome activation and IL-33 release. Paracrine IL-33 mobilized and activated mast cells, resulting in profibrotic factor release and epithelial migration. Addition of IL-33 neutralizing antibody in the co-culture model attenuated mast cell activation and fibrosis-promoting effects.

Discussion: Collectively, our data indicate that Duox2 or the downstream IL-33 pathway is a potential therapeutic strategy for intestinal fibrosis.

Conclusion: Our findings identify a Duox2-NLRP3-IL-33-Mast Cell axis in chronic colitisassociated fibrosis. Epithelial Duox2 activation induces NLRP3-mediated IL-33 release, which promotes mast cell infiltration.