P149 DECREASED COLONIC ACTIVIN RECEPTOR-LIKE KINASE 1 DISRUPTS EPITHELIAL BARRIER INTEGRITY AND IS ASSOCIATED WITH A POOR CLINICAL OUTCOME IN CROHN’S DISEASE
2020
Objective: Intestinal epithelial cell (IEC) barrier dysfunction is critical to the development of Crohns disease (CD). However, the mechanism is understudied. We recently reported increased microRNA-31-5p (miR-31-5p) expression in colonic IECs of CD patients, but downstream targets are unknown. Design: MiR-31-5p target genes were identified by integrative analysis of RNA- and small RNA-sequencing data from colonic mucosa and confirmed by qPCR in colonic IECs. Functional characterization of Activin Receptor-Like Kinase 1 (ACVRL1 or ALK1) in IECs was performed ex vivo using 2 dimensional-cultured human primary colonic IECs. The impact of altered colonic ALK1 signaling in CD for the risk of surgery and endoscopic relapse was evaluated by a multivariate regression analysis and a Kaplan-Meier estimator. Results: ALK1 was identified as a target of miR-31-5p in colonic IECs of CD patients and confirmed using a 3-UTR reporter assay. Activation of ALK1 restricted the proliferation of colonic IECs in an EdU proliferation assay and down-regulated the expression of stemness-related genes. Activated ALK1 signaling directed the fate of colonic IEC differentiation toward colonocytes. Down-regulated ALK1 signaling was associated with increased stemness and decreased colonocyte-specific marker expression in colonic IECs of CD patients compared to healthy controls. Activation of ALK1 enhanced epithelial barrier integrity in a trans-epithelial electrical resistance permeability assay. Lower colonic ALK1 expression was identified as an independent risk factor for surgery and associated with a higher risk of endoscopic relapse in CD patients. Conclusion: Decreased colonic ALK1 disrupted colonic IEC barrier integrity and associated with deteriorated clinical outcomes in CD patients.
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