[Vitamin D inhibits PM-induced autophagy and cytokine release of A549 human alveolar epithelial cells].

Objective To investigate how vitamin D (VD) affects fine particulate matter (PM)-induced autophagy and cytokines production in A549 human alveolar epithelial cells. Methods PM samples were prepared at the upper part of an acetylene diffusion flame burner. A549 cells were treated with PM in vitro, and/or were treated with VD or autophagy inhibitor 3-methyladenine (3-MA). Western blot analysis was employed to analyze the level of LC3-II/I and Beclin-1 in A549 cells with different groups. Real time quantitative PCR was used to detect the mRNA expression of interleukin-25 (IL-25), IL-33 and thymic stromal lymphopoietin (TSLP). The formation of autophagosomes was observed by transmission electron microscopy. Results LC3-II/I ratio and beclin-1 protein expression were found increased in A549 cells after PM treatment, and autophagosome were increased too. There was a marked decrease of PM-induced autophagy with VD treatment. After 3-MA treatment, the autophagy was inhibited. Then, PM continued to induce autophagy, while VD could also reverse it. PM promoted the secretion of IL-25, IL-33 and TSLP by inducing autophagy in A549 cells while this process was inhibited by 3-MA and VD. Conclusion VD can inhibit PM-induced autophagy and cytokine release in A549 cells, thus playing a protective role.