| [Objective]Silicosis, is a significant type of pneumoconiosis in consequence of inhaling a large amount of free silica dust in long period of time characterized mainly by a widespread nodular fibrosis in lung. Cardinal symptoms of silicosis are diffused alveolar inflammation, disordered alveolar structure and pulmonary fibrosis. Macrophages and its function of lysosome take important part in the formation process of silicosis. Autophagy is the basic catabolic mechanism that autolysosome fused by lysosome and autophagosome which involves cell degradation of unnecessary or dysfunctional cellular components and degrades its contents. The breakdown of cellular components can ensure cellular survival by maintaining cellular energy levels and organelle’s refresh. Participating in progressions of different kinds of diseases is one of functions autophagy displays. The mechanism autophagy plays a role in the progress of silicosis remains to be determined. As the major occupational disease in our country, silicosis makes people’s health in danger severely, especially the workers in mine field. Objects in this research are to elucidate effects autophagy acting on silicosis and possible mechanisms in this process. [Materials and methods]60adult male SD rats, weighs between150g and200g, were divided into5groups and averagely divided into2time points (2months and4months). Group1is group of negative control which was treated with NS lml by single trachea way followed by treating NS by lavage at interval day. Group2is group of chloroquine control which was treated with NS lml by single trachea way followed by treating chloroquine at concentration of50mg/kg by lavage at interval day. Group3is group of SiO2model which was treated with SiO250mg by single trachea way. Group4is group of chloroquine treatment which was treated with SiO250mg by single trachea way followed by treating chloroquine at concentration of50mg/kg by lavage at interval day. Group5is group of chloroquine pretreatment which was pretreated with chloroquine by gavage for2weeks every other day, and then treated with SiO250mg by single trachea way followed by treating chloroquine at concentration of50mg/kg by lavage at interval day. Growth situations were observed including weight loss, polypnea, dyspnea and activity decline. Weights of mice were recorded every other day. At2months, we executed rats of first part and calculated the lung coefficient. HE stain was used to observe pathological changes in lung; MASSON stain was used to observe collagenous fiber changes in lung; TEM was used to observe ultrastructure changes in macrophage. Western blotting was used to analyze the autophagy related protein P62and LC3levels and use IHC for P62and LC3in the same tissues. At4months, we executed the rest of rats and use the same index.[Results]During the silicosis formation, CQ treatment can inhibit the weight gain notably when compared to the control, while other treatments don’t show differences. After SiO2treatments, the lung became white, big and strong but pliable in texture. There were many white and spot nodules diffused distribution on the surface of lung. Each group can increase the lung coefficient notably when compared to the control, and CQ treatment groupã€CQ pretreatment group can decrease the lung coefficient notably when compared to the SiO2model group. After SiO2treatments, HE staining shows that alveolar wall and interstitial tissue became thick and broad, gathering the macrophages and producing fiber. CQ treatment groups had more lesions in the light than SiO2model group. At the time point about two month, MASSON staining shows CQ treatment groups had few content of collagenous fiber notably than SiO2model group; but at the time point about four month, CQ treatment groups had nothing difference compared to SiO2model group. After SiO2treatments, TEM shows that lysosomes of macrophage and alveolar type II cell became active and many autolysosomes became muddy and vacuolization. The SiO2model group was damaged badly. At the time point about two month, IHC shows CQ treatment groups had more expression of protein P62notably than SiO2model group; but at the time point about four month, CQ treatment groups had less expression of protein P62notably compared to SiO2model group. CQ treatment groups had less expression of protein LC3notably than SiO2model group. Western blotting shows that CQ treatment groups had less expression of protein P62and LC3notably than SiO2model group.[Conclusion]In our experiment, inhibitting autophagy could delay silicosis formation, but couldn’t change the pathological ending. |
