Poricoic acid A alleviates dextran sulfate sodium-induced colitis in mice by regulating AMPK/mTOR-mediated autophagy and inhibiting intestinal epithelial cell apoptosis

doi:10.12122/j.issn.1673-4254.2026.01.14

Abstract

Abstract:

Objective To investigate the mechanism of poricoic acid A (PAA) for alleviating dextran sulfate sodium (DSS)-induced colitis in mice. Methods Eighteen C57BL/6 mice were randomly divided into control group, DSS-induced colitis model group, and PAA intervention (10 mg/kg) group. The changes in body weight, colon length, disease activity index (DAI), and histopathological scores of the mice were evaluated. In a DSS-induced Caco-2 cell model, the changes in expressions of ZO-1, claudin-1, Bcl-2, Bax, cleaved caspase-3, LC3-II/I, and P62 were detected. Molecular docking and Western blotting were used to analyze the mechanisms underlying the ameliorating effect of PAA on DSS-induced colitis. Results In the mouse models of DSS-induced colitis, PAA significantly ameliorated DSS-induced weight loss, colon shortening, and elevation of DAI scores while reducing colonic IL-1β and TNF-α levels. HE staining showed that PAA obviously alleviated colonic crypt damage, reduced inflammatory cell infiltration, and lowered histopathological scores of the colon. AB-PAS staining revealed significantly increased goblet cell counts in PAA-treated mice compared to those in DSS group. In DSS-induced Caco-2 cells, PAA treatment effectively inhibited DSS-induced downregulation of the tight junction proteins, reduced Bax and cleaved caspase-3 expressions, increased Bcl-2 expression and the LC3-II/I ratio, and decreased P62 expression. Mechanistic study suggested that PAA targeted the AMPK/mTOR pathway to activate autophagy and suppress cell apoptosis. Conclusion PAA protects intestinal barrier function and alleviates DSS-induced colitis in mice by activating AMPK/mTOR-mediated autophagy and inhibiting intestinal epithelial cell apoptosis.

Key words: inflammatory bowel disease, poricoic acid A, autophagy, apoptosis, intestinal barrier

Tong QIAO, Lin YIN, Keni ZHANG, Minzhu NIU, Ju HUANG, Zhijun Geng, Jing LI, Jianguo HU. Poricoic acid A alleviates dextran sulfate sodium-induced colitis in mice by regulating AMPK/mTOR-mediated autophagy and inhibiting intestinal epithelial cell apoptosis[J]. Journal of Southern Medical University, 2026, 46(1): 131-140.

Figures/Tables 11

Fig.1 Therapeutic effects of PAA on DSS-induced colitis in mice. A: Changes in body weight of the mice. B: Disease activity index (DAI) scoring. C: Macroscopic evaluation of colon morphology. D: Quantitative analysis of colon length. WT: Wild type group; DSS: DSS-induced model group; PAA: Treatment group DSS. n=6, *P<0.05 vs WT group. #P<0.05 vs DSS group.

Fig.2 Effects of PAA intervention on intestinal histopathological damage and expression of inflammatory factors in DSS mice. A, B: ELISA results of TNF-α (A) and IL-1β (B) in mice intestinal mucosa. C: AB-PAS staining of colon tissues in different groups. D: HE staining of colon tissues in different groups. E: Histopathological scores of colon tissues. n=6, *P<0.05 vs WT group. #P<0.05 vs DSS group.

Fig.3 Effect of PAA on intestinal barrier function in DSS-induced colitis mice. A: Immunofluorescence staining of ZO-1 and claudin-1 in the colon. B, C: Quantitative analysis of ZO-1 and claudin-1 expression levels in the intestinal mucosa by Western blotting. n=6, *P<0.05 vs WT group; #P<0.05 vs DSS group.

Fig.4 Effect of PAA on intestinal epithelial cell apoptosis in DSS-induced colitis mice. A: TUNEL staining of colon tissues. B: Quantitative analysis of intestinal epithelial cell apoptosis rate. C, D: Western blotting of Bcl-2, Bax, and cleaved caspase-3 (C-caspase3) expression levels in colonic mucosa. n=6, *P<0.05 vs WT group; #P<0.05 vs DSS group.

Fig.5 Effects of PAA on cellular autophagy in DSS-induced colitis mouse models. A: Immunofluorescence images of LC3B in the colon. B: Western blotting of LC3-I, LC3-II, and P62 expressions in the intestinal mucosa. C: Quantitative analysis of the LC3-II/LC3-I protein ratio. D: Quantitative analysis of P62 protein expression. n=6, *P<0.05 vs WT group; #P<0.05 vs DSS group.

Fig.6 Effect of PAA on autophagy in DSS-induced Caco-2 cells. A: Immunofluorescence staining of LC3B in Caco-2 cells. B: Western blotting of LC3-I, LC3-II, and P62 expression. C: Quantitative analysis of the LC3-II/LC3-I ratio. D: Quantitative analysis of P62 protein level. Control: Normal control group; C-DSS: DSS-induced model group; C-PAA: PAA treatment group. n=3, *P<0.05 vs Control group; #P<0.05 vs C-DSS group.

Fig.7 Effect of PAA on DSS-induced apoptosis of Caco-2 cells. A: TUNEL staining of Caco-2 cells. B: Quantitative analysis of apoptosis rate. C: Western blotting of Bcl-2, Bax, and C-caspase3 expressions. D: Relative protein expression levels of Bcl-2, Bax, and C-caspase3. n=3, *P<0.05 vs Control group; #P<0.05 vs C-DSS group.

Fig. 8 Therapeutic effects of PAA on DSS-induced barrier damage in Caco-2 cells. A: Immunofluorescence staining of ZO-1 and claudin-1 in Caco-2 cells (Scale bar=100 μm). B, C: Western blotting for detecting protein expression levels of ZO-1 (B) and claudin-1 (C) in Caco-2 cells. n=3, *P<0.05 vs Control group. #P<0.05 vs C-DSS group.

Fig.9 Effect of PAA on the AMPK/mTOR pathway in the mouse models. A: Molecular docking analysis of PAA with AMPK. B, C: Western blotting for detecting protein expression levels of p-AMPK, AMPK, p-mTOR, and mTOR in mouse colon tissues. n=6, *P<0.05 vs WT group; #P<0.05 vs DSS group.

Fig.10 Effects of PAA treatment on AMPK/mTOR signaling in DSS-induced Caco-2 cells. A: Western blotting for p-AMPK, AMPK, p-mTOR, and mTOR expressions. B: Quantitative analysis of p-AMPK/AMPK and p-mTOR/mTOR protein expression ratios. n=3, *P<0.05 vs Control group. #P<0.05 vs C-DSS group.

Fig.11 PAA regulates autophagy and apoptosis in Caco-2 cells by activating the AMPK/mTOR pathway. A: Immunofluorescence staining of LC3B in Caco-2 cells. B: Western blotting for LC3-I, LC3-II, and P62 expressions. C: Quantitative analysis of the LC3-II/LC3-I ratio. D: TUNEL staining of Caco-2 cells. E: Quantitative analysis of apoptosis rate. F: Western blotting for Bcl-2, Bax, and C-caspase3 expressions. G: Relative protein expression levels of Bcl-2, Bax, and C-caspase3. C-PAA: PAA treatment group; C-PAA+SBI: PAA treatment group+SBI-0206965. n=3, *P<0.05 vs C-PAA group.

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