[MiR-4508 regulates chrysotile asbestos induced inflammation in human bronchial epithelial cells through the PI3K/AKT...

Objective: To explore the molecular mechanism of miR-4508 regulating the inflammatory response of human bronchial epithelial cells induced by representative chrysotile asbestos. Methods: The chrysotile asbestos was ground into ultrafine dust using a horizontal planetary instrument, and human bronchial epithelium (16HBE) cells were taken as the object of infection. Cell survival rate was detected by cell counting kit-8 method, cytotoxicity was detected by lactate dehydrogenase (LDH) kit. The released of inflammatory factor IL-6 was detected by electrochemical luminescence. The released inflammatory factor IL-8 was detected by enzyme-linked immunosorbent assay. The expression level of miR-4508 was screened and verified by reverse transcription-quantitative real-time polymerase chain reaction. After 16HBE cells were treated with AKT inhibitor MK2206, the phosphorylation levels of AKT and PTEN were detected by western blot. The expression levels of AKT and PTEN and the contents of IL-6 and IL-8 were detected in miR-4508 overexpression and interference experiments. Results: With the increase of chrysotile asbestos exposure concentration, the cell survival rate decreased in a concentration-dependent manner, and the LDH content gradually increased. The secretion of IL-6 and IL-8 in chrysotile 25, 50 and 75 µg/ml groups were (325.92±8.61) pg/ml, (331.51±4.96) pg/ml, (378.74±13.77) pg/ml, and (94.95±3.11) pg/ml, (357.60±1.80) pg/ml, (537.19±3.11) pg/ml, respectively, while the group with 0 µg/ml chrysotile was (95.85±1.20) pg/ml and (7.81±0.00) pg/ml (P＜0.05). In addition, chrysotile asbestos exposure to 16HBE could induce the high expression of miR-4508. After pretreatment with MK2206, the phosphorylation levels of AKT and PTEN were decreased, the contents of IL-6 and IL-8 were significantly decreased, and the expression level of miR-4508 was significantly reduced. Overexpression of miR-4508 significantly increased the expressions of AKT and PTEN, and the contents of IL-6 and IL-8 (P＜0.01). After interfering with miR-4508, the expressions of AKT and PTEN were significantly decreased, and the contents of IL-6 and IL-8 were significantly decreased (P＜0.01). Conclusions: Chrysotile asbestos can induce the inflammatory response of 16HBE cells and up-regulate the expression level of miR-4508. The up-regulation of miR-4508 promotes the 16HBE inflammatory response induced by chrysotile asbestos through the PI3K/AKT pathway.