To explore the role and molecular mechanism of PRDM5 in Crohn's disease intestinal epithelial barrier injury by regulating Wnt/β-catenin signaling pathway.

A retrospective case-control study design was adopted. A total of 50 patients with Crohn's disease (L2/L3 subtypes, without biological agent administration, assigned to the Crohn's disease group) who were diagnosed in Zhangjiagang First People's Hospital from January 2021 to December 2023, as well as 50 healthy controls (with normal intestinal mucosal tissues after intestinal polypectomy and pathologically confirmed to be free of inflammatory changes), were retrieved from the hospital's medical record archive system. Immunohistochemical H-score was used to evaluate the co-localization of PRDM5 and active-caspase3 in intestinal tissues. Crohn's disease model of BALB/c mice induced by TNBS was established (5 mice in TNBS group and 5 mice in ethanol solvent group). The disease activity index (DAI), histopathological score (HAI) and the proportion of PRDM5 positive cells were evaluated, and the expressions of β-catenin, c-Myc, Cyclin D1 and TCF4 were detected by Western blotting. In vitro, HT-29 cells were stimulated by IFN-γ (50 ng/ml) and divided into blank control group, IFN-γ group and siRNA-PRDM5 intervention group. The LC3Ⅱ/Ⅰ, p62, active-caspase3 and Bax/Bcl-2 ratio were detected by Western blotting, and the apoptosis rate was analyzed by flow cytometry. The translocation of β-catenin nucleus was observed by immunofluorescence, and the expression of tight junction proteins (such as claudin-2, occludin, ZO-1), transepithelial resistance (TEER) and paracellular permeability (FITC-Dextran) were further detected.

The positive rate of PRDM5, H-score and co-location rate with active-caspase3 in Crohn's disease group were significantly higher than those in the healthy control group (all P<0.001). The proportion of DAI, gross morphological score, HAI and PRDM5 positive cells in the TNBS model group was significantly higher than that in the ethanol solvent group (all P<0.001), and PRDM5 was negatively correlated with the expression of β-catenin, c-Myc, Cyclin D1 and the nuclear translocation rate of TCF4 (r values were -0.852, -0.774, -0.823 and -0.791, all P<0.01). After knocking down PRDM5, the autophagy activity, β-catenin expression and cell viability of HT-29 cells were significantly increased (all P<0.001), while apoptosis rate and Bax/Bcl-2 ratio were significantly decreased (all P<0.001). In addition, knocking down PRDM5 could significantly increase the expression levels of claudin-2, occludin, ZO-1 and other tight junction proteins (P<0.005), significantly increase the TEER value (P<0.001), and reduce the permeability of paracellular cells (FITC-Dextran permeability decreased, P<0.001), indicating that it has a protective effect on the intestinal epithelial barrier function.

PRDM5 mediates autophagy-apoptosis imbalance and barrier function damage of intestinal epithelial cells by inhibiting Wnt/β-catenin pathway activity, and its targeted intervention may provide potential therapeutic strategies for mucosal repair of Crohn's disease.