[The regulatory effect of PI3K/Akt/HIF-1α glycolytic signaling pathway on the metabolites in urine of mice with bleomycin-induced pulmonary fibrosis model].

Objective: To investigate the regulatory effects of the phosphatidylinositol-4, 5-bisphosphate 3-kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) glycolytic signaling pathway on urinary metabolites in a mouse model of bleomycin-induced pulmonary fibrosis. Methods: From May to October 2023, 36 C57BL/6 mice were randomly divided into six groups (n=6 each): control (BD) group, bleomycin model (BM) group, early PI3K inhibitor (LY294002) intervention (BZLY) group, late PI3K inhibitor intervention (BWLY) group, early HIF-1α inhibitor[2-methoxyestradiol(2-ME2) ] intervention (BZ2M) group, and late HIF-1α inhibitor intervention (BW2M) group. Idiopathic pulmonary fibrosis model was established in mice by a single non-exposed intratracheal instillation of 4 mg/kg bleomycin. Mice in the intervention groups received intraperitoneal injections of 1.0 mg/kg LY294002 or 16 mg/kg 2-ME2 starting on day 2 or day 22 post-exposure, lasting 41 or 21 days, respectively. On day 42 post-exposure, urine of each group of mice was collected, the mice were sacrificed and the lung tissues were collected. Lung histopathology of mice was assessed by HE staining. Urine metabolomics was performed, and differential metabolites were identified using principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), followed by pathway enrichment analysis. Results: At 42 days post-exposure, the mice in BM group showed inflammatory cell infiltration in the pulmonary interstitium and alveolar spaces, along with pulmonary interstitial fibrosis. The degrees of inflammatory cell infiltration and fibrosis in the lung tissues of the mice in each intervention groups were all alleviated. Compared with the BD group, 5 differential metabolites were identified in the urine of mice in the BM group. Compared with the BM group, the BZLY, BWLY, BZ2M, and BW2M groups exhibited 5, 3, 4, and 6 differential urinary metabolites in mice, respectively. Pathway enrichment analysis revealed 6 significantly altered metabolic pathways: purine metabolism, linoleic acid metabolism, α-linolenic acid metabolism, riboflavin metabolism, sphingolipid metabolism, and tyrosine metabolism (P<0.05) . Conclusion: The PI3K/Akt/HIF-1α glycolytic signaling pathway may regulate the development and progression of idiopathic pulmonary fibrosis through purine metabolism, linoleic acid metabolism, α-linolenic acid metabolism, riboflavin metabolism, sphingolipid metabolism, and tyrosine metabolism pathways.