Article I. metformin affects H1N1-induced apoptosis in lung epithelial cells by the miR-130a-5p-regulated PI3K/AKT signaling pathway.

Background: H1N1 influenza virus can cause diffuse alveolar damage, such as pneumonia and pulmonary fibrosis, when it infects the respiratory tract. Metformin not only improves chronic inflammation but also has direct anti-inflammatory effects. Therefore, the focus of this study was on the molecular mechanism and regulatory mechanism of metformin against influenza virus in alleviating lung disease.

Methods: An animal model of H1N1 infection was constructed by injecting H1N1 virus into mice. The lung tissues of H1N1-infected mice treated with metformin were subjected to miRNA-seq, and the data were analyzed. The weights and lung indices of the mice were evaluated. The pathological tissues were stained with HE and Masson's trichrome. H1N1-infected A549 cells were used to construct a model of H1N1 infection. Western blotting was used to detect virus-, apoptosis-, PI3K/AKT signaling pathway-, and inflammation-related proteins. The expression of miR-130a-5p was detected by RT‒qPCR. IF was used to detect virus replication. TUNEL and flow cytometry were used to detect apoptosis. ELISA was used to detect inflammatory factors. Cell proliferation was detected using CCK-8 and EDU assays.

Results: Metformin effectively alleviated H1N1-induced fibrosis, inflammation and apoptosis. Bioinformatics analysis revealed that miR-130a-5p was the only miRNA that was differentially expressed in both groups (normal vs. H1N1 group; H1N1 vs. metformin group). In H1N1-induced A549 cell experiments, metformin promoted the upregulation of miR-130a-5p, thereby inhibiting PI3K/AKT signaling pathway activation. However, the miR-130a-5p inhibitor and PI3K/AKT agonist weakened the protective effects of metformin on A549 cell proliferation, anti-apoptosis and viral inhibition to some extent.

Conclusion: Metformin alleviates H1N1-induced fibrosis, inflammation, and apoptosis by inhibiting the aberrant activation of PI3K/AKT by the promotion of miR-130a-5p expression.