miR-31a-5p targeting Crebbp suppresses Wnt/β-catenin and TGF-β pathways to alleviate oil mist particulate matter-induced pulmonary fibrosis

Oil mist particulate matter (OMPM), which is a representative airborne contaminant pervasive in occupational and residential environments, poses threats to human health and sustainable development, particularly through its detrimental effects on respiratory integrity. Pulmonary fibrosis (PF) can lead to high mortality and impair quality of life, and this disease is currently widely recognized by the academic community as an important reference endpoint for studying the toxic effects associated with OMPM. This study aimed to elucidate the molecular mechanism underlying OMPM exposure-induced pulmonary fibrogenesis by establishing integrated in vivo and in vitro OMPM exposure models combined with transcriptomic sequencing. The results demonstrated that OMPM exposure induced significant pathological alterations in rat lungs, including structural abnormalities of lung tissue, infiltration of inflammatory cells, alveolar destruction, and extensive fibrous deposition. A remarkable increase in fibrosis-related indices was observed, including connective tissue growth factor, fibroblast growth factor 2, platelet-derived growth factor, TIMP metallopeptidase inhibitor 1, collagen I, collagen III, and alpha smooth muscle actin, whereas the expression levels of MMP2, MMP9, and MMP13 significantly decreased, accompanied with increased levels of oxidative stress and inflammation, indicating that OMPM exposure can induce PF in rats. Transcriptomic sequencing analysis revealed that OMPM exposure induces a significant change in the expression of miR-31a-5p, and subsequent dual-luciferase reporter assay confirmed that Crebbp was the target gene of miR-31a-5p. In the present study, three cellular models were employed to further validate these findings: an OMPM-exposed RLE-6TN cell model, an RLE-6TN cell model transfected with Crebbp siRNA, and an RLE-6TN cell model transfected with an miR-31a-5p overexpression vector. These models were cross-validated through in vivo experiments, and the results indicated that miR-31a-5p can target and regulate Crebbp, thereby inhibiting the Wnt/β-catenin and TGF-β signaling pathways, which alleviate OMPM-induced PF.