[AAV vector targeting pulmonary epithelial cells to inhibit ArhGAP29 expression ameliorates pulmonary fibrosis in silicosis mice]

Objective: To investigate the mechanism by which inhibition of Rho GTPase-activating protein 29 (ArhGAP29) affects epithelial-mesenchymal transition (EMT) and the progression of pulmonary fibrosis induced by silicon dioxide (SiO(2)) . Methods: From September 2024 to June 2025, forty SPF-grade male C57BL/6N mice were used to establish a silicosis model via intratracheal instillation of SiO(2). At 14 days after SiO(2) exposure, adeno-associated virus (AAV) carrying ArhGAP29 inhibitor was administered to infect the lungs of silicotic mice. Mice were divided into four groups (n=10 per group) : saline group (intratracheal instillation of sterile saline), SiO(2) group (intratracheal instillation of 50 μl 50 mg/ml SiO(2) suspension), SiO(2)+empty vector AAV group (AAV-BLANK group, SiO(2) modeling followed by negative control AAV intervention), and AAV-si-ArhGAP29 group (SiO(2) modeling followed by targeted ArhGAP29 interference AAV intervention) .Hematoxylin-eosin (HE) staining was performed to observe pathological changes in lung tissues. Hydroxyproline (HYP) content detection was used to evaluate the degree of pulmonary fibrosis. Western blotting was applied to detect the protein expression levels of ArhGAP29, α-smooth muscle actin (α-SMA) and E-cadherin (E-cad) in lung tissues. Immunofluorescence (IF) staining was conducted to detect the expression and localization of α-SMA and ArhGAP29. Intergroup comparisons between two groups with normal distribution and homogeneity of variance were analyzed by Student's t-test, while non-parametric tests were adopted for data not conforming to normal distribution. Results: Compared with the saline group, the expression levels of ArhGAP29 and α-SMA were significantly upregulated, while E-cad expression was markedly downregulated in lung tissues of silicotic mice (P<0.05). Compared with the AAV-BLANK group, the number and area of silicotic nodules were significantly reduced, pulmonary fibrosis was markedly alleviated, α-SMA expression was downregulated and E-cad expression was upregulated in the AAV-si-ArhGAP29 group, with statistically significant differences (P<0.05) . Conclusion: Inhibition of ArhGAP29 expression effectively alleviates SiO(2)-induced pulmonary fibrosis, and its mechanism may be associated with the suppression of epithelial-mesenchymal transition (EMT) .