A Novel Insight into Chronic Pancreatitis Pathogenesis: the USP1/ITGB5 Axis-Mediated Stellate Cell Activation.

Chronic pancreatitis (CP) is characterized by chronic pancreatic inflammation and progressive fibrosis. This study investigated the role of ubiquitin-specific peptidase 1 (USP1), a protein-stabilizing deubiquitinase, in CP. C57BL/6J mice were given 8-week repetitive intraperitoneal cerulein (50 µg/kg) injections to establish the CP model. USP1 expression in CP mouse pancreatic tissues was 3-fold higher than in controls. Lentivirus-mediated Usp1 knockdown reduced pancreatic inflammatory cell infiltration, trypsin activity, and proinflammatory cytokine levels. Additionally, Usp1 knockdown inhibits collagen deposition and fibrosis of the pancreas. In vitro, USP1 was upregulated in activated pancreatic stellate cells (PSCs) induced by TGF-β1 (5 ng/mL). USP1 knockdown decreased the expressions of collagen type I alpha 1 chain (COL1A1), COL1A2, fibronectin, and α-smooth muscle actin (α-SMA), suppressing PSC activation and extracellular matrix production. Immunoprecipitation-liquid chromatography/mass spectrometry (IP-LC/MS) and label-free proteomics identified integrin subunit beta 5 (ITGB5) as a potential target protein of USP1. USP1 promoted ITGB5 deubiquitination/stabilization, while USP1 knockdown reduced ITGB5 expression. Rescue experiments showed ITGB5 overexpression reversed the inhibitory effect of USP1 knockdown on PSC activation. Moreover, ITGB5 knockdown inhibited PSC activation via suppressing PI3K/AKT pathway. In conclusion, USP1 knockdown inhibits PSC activation by suppressing the ITGB5-PI3K-AKT axis, thereby alleviating the pathological progression of CP.