Effects Of Autophagy On Lung Damage In Rats Caused By Exposed Arsenic In Drinking Water

Objective To investigate the role of autophagy in lung injury induced by arsenic exposure in drinking water and the relationship between inflammation cytokines and autophagy.Method 160 specific pathogen free?SPF?healthy male SD rats were randomly selected and divided into control group,5ppb?5?g/L?group,10ppb?10?g/L?group,20ppb?20?g/L?group,50ppb?50?g/L?group,100ppb?100?g/L?group,100ppb+3MA group and 3MA group,with twenty in each group.Arsenic exposure groups were poisoned by freely drinking water containing sodium arsenite?NaAsO₂?of different concentrations.In contrast,the control group freely drank water without sodium arsenite.Then we kill the rats on 7th day?14th day?21st day?28th day.Then we collected bronchoalveolar lavage fluid?BALF?and counted its inflammatory cell using whole-lung lavage in vivo.The pathologic and transmission electron microscopy changes in the lung were examined.Then we ascertained the content of TNF-?,IL-6,IL-10,IL-1?,cortisol in bronchoalveolar lavage fluid?BALF?using ELISA and detected the expression level of p62,LC3?related to the autophagy in lung tissue using Western blotting.Results 1.After 28 days poisoned by sodium arsenite?NaAsO₂?,pathology results of the rat lung tissue showed that for the control group,the alveolar structure was clear,the alveolar wall was thin,the alveolar wall capillary had no obvious expansion and congestion and no obvious thickening of alveolar septum and inflammatory cell infiltration were observed;for the 5,10 ppb NaAsO₂exposure group,alveolar septa widened,partial bronchial hemorrhaged and bronchial and perivascular edema was obsearved;for the 20ppb NaAsO₂exposure group,bronchial wall and surrounding tissue inflammatory cells and smooth muscle were broken;for the 50ppb NaAsO₂exposure group,alveolar cavity with protein edema fluid exudation was observed;for the 100ppb NaAsO₂exposure group,part of the bronchial hemorrhaged,part of the regional fibrous tissue hyperplasia was observed;for the 100ppb+3MA NaAsO₂exposure group,severe pulmonary interstitial inflammation and lymphocytic infiltration were observed;for the 3MA injection group,the rats were normal under the lung microscope.2.The results of transmission electron microscopy show:after 28 days exposure to NaAsO₂,no autophagosomes were observed in the control group but autophagosomes were observed in 5 ppb,10 ppb,20 ppb,50 ppb,100 ppb,100 ppb+3MA groups.3.Following is the changing of cytokine in BALF supernatant of rats:?1?The levels of cytokines TNF-?,IL-1?and IL-6 in BALF supernatant of NaAsO₂-treated rats increased with the dose and time,and IL-6 content in all exposure groups except 3MA group,statistically gradually increased with time,with the deviance compared to the control group statistically significant;and there was a significant difference between the fourth week and the first and second weeks among50ppb,100ppb and 100ppb+3MA groups.The levels of IL-1?in the alveolar lavage fluid of each group were significantly higher than those of the control group and the levels of IL-1?in the alveolar lavage fluid content increases as time goes.As for TNF-?,in the first week of exposure,there was statistical significant difference between 100ppb+3MA exposure group and the control group;in the second,third,fourth week,the difference between 50 ppb,100 ppb,100 ppb+3MA groups and the control group was statistically significant;as time of exposure increases,the content of TNF-?in alveolar lavage fluid increased,but the difference was not statistically significant.?2?IL-10 and Cortisol levels decreased with the dose and time of NaAsO₂exposure,and the difference was statistically significant at each time point.4.the expression level of protein related to the autophagy in lung tissue:compared with the control group,the expression of p62 in lung tissue of NaAsO₂group increased?P<0.05?,and there was dose-response relationship.Compared with the control group,the expression of LC3?protein in the lung tissue of NaAsO₂group was significantly decreased?P<0.05?,and there was dose-response relationship.Conclusions Arsenic enters the rat through drinking water,leading to increased proinflammatory cytokines in lung tissue and decreased antiinflammatory cytokines,cell autophagy levels decreased,eventually leading to lung injury in rats...