[Changes and significance of autophagy in rat lung injury induced by gas explosion]

Objective: To explore the changes and significance of autophagy in acute lung injury (ALI) induced by gas explosion in rats. Methods: In February 2018, the gas explosion in underground coal mine was simulated by large tunnel explosion experiment system, SD rats were randomly divided into control group and 6 distance groups (40 m, 80 m, 120 m, 160 m, 200 m, 240 m) with 18 rats in each group. The respiratory function of rats 24 h before and after explosion was detected. Post-explosion rats were anesthetized and sacrificed, histopathological changes of lung were observed by HE staining. Immunohistochemistry was performed to detect the in situ expression of autophagy marker protein microtubule-associated protein 1 light chain 3 (LC3B) . The expression levels of autophagy related gene 12 (Atg12) , LC3B, P62, lysosomal associated membrane protein 2 (Lamp2) , B-cell lymphoma/leukemia-2 (Bcl-2) and Bcl2 interaction protein (Beclin-1) were detected by Western blot. Results: After gas explosion, the rats in 80 m distance point group had the hightest mortality (n=13, 72.22%) and the most severe lung injury degree, and the histopathological scores was (4.00±0.00) point. After gas explosion, the minute ventilation volume (MVb) , maximum inspiratory flow rate (PIFb) and maximum expiratory flow rate (PEFb) of rats were lower than before the gas explosion (P<0.05) . The respiratory frequency of rats in 80 m, 200 m, and 240 m distance point groups were significantly higher than that in the control group (P<0.05) . The expression levels of LC3B in 40 m, 80 m, 120 m, 160 m, and 200 m distance point groups were higher than that in the control group (P<0.05) . The relative expression levels of Atg12 and LC3BⅡ/Ⅰ in lung tissues of rats in different distance point groups were higher than those in the control group (P<0.05) . The relative expression levels of Beclin1 in 40 m, 80 m, 120 m, and 160 m distance point groups were significantly higher than that in the control group (P<0.05) . The relative expression levels of P62 in 80 m, 160 m and 200 m distance point groups were lower than that in the control group (P<0.05) . The relative expression levels of Lamp2 and Bcl-2 in lung tissues of rats in all distance groups except 240 m distance group were lower than those in the control group (P<0.05) . Conclusion: Gas explosion could induce increased autophagy in lung tissues of ALI rats. Autophagy-related signaling pathway could be involved in the pathophysiological process of ALI in rats caused by gas explosion, then the autophagy and the severity of the lesion showed a significant positive correlation.