The Study Of Lung Remodeling In Atherogenic Diet Treated C57BL/6J Mice

Objective:The damage of lipid metabolism disorder on multiple organ was well established. Present studies were focused on the relationship between lipid metabolism disorder and vascular blood vessel, liver and kidney diseases, the studies related to hyperlipidemia and lung remodeling has just begun. Some lipid metabolism related gene knockout studies suggested that disturbance of lipid metabolism might lead to abnormal lipid accumulation and pathological changes in lung tissues, but the direct evidence of lung remodeling in high cholesterol diet treated mice was absent.In the present study, C57BL/6J mice were treated with either normal diet or high cholesterol diet, Casein injection was set up as the chronic inflammatory pressure. The lipid content and pathologic changes in mice lung were studied after the treatments and in vitro studies of A549 cells were used to interpret the possible mechanism.Methods:1. 8-week old C57BL/6J mice were fed with normal or atherogenic diet for 14 weeks respectively. Chronic inflammation status in mice was set up by injecting 10% of casein subcutaneously. Lung tissues were evaluated for immunohistochemical and lipid profile studies.2. The morphological changes of mice lung were detected by Oil Red O staining, HE staining and immunohistochemical assay.3. Triglyceride, total cholesterol and free cholesterol content of mice lung were detected using specific enzymatic methods.4. The lipid deposition of ox-LDL or LPS treated A549 lung adenocarcinoma cells were studied using oil red O staining.Results:1. The oil red O staining results showed that: There is almost no oil red O dye deposition in the lung of normal diet group; Only a small amount of oil red O staining was visualized in the lung tissue of normal diet with casein group; Oil red O staining significantly increased in the atherogenic diet group and in the atherogenic diet with casein group. The deposition of lipid was visualized mainly in type II alveolar epithelial cells. HE staining results showed that: The structure of lung was not changed in the normal diet group; increased thickness of alveolar septa, lymphocytes, alveolar macrophages, and a small number of neutrophils infiltration were presented in the lungs of atherogenic diet group and in the atherogenic diet with casein group; Lymphoid follicles were formed in some peri-bronchiole area. PCNA immunohistochemical staining results showed that: Compared to the normal diet treated mice lung, the number of proliferating cells increased in the lungs of atherogenic diet treated mice. The condition is more severe in the atherogenic diet with casein group.2. For the lipids tested in this study, only triglycereide content increased in the lungs of atherogenic diet group compared to other groups. There is no significant influence of imflammatory pressure to the lipid content of mice lung.3. Oil red O staining result showed that 50μg/ml ox-LDL and 200ng/ml LPS treatment increased the lipid deposition in the cultured A549 cells.Conclusion:1. Compared with normal diet-fed mice, the lungs of atherogenic diet-fed mice showed large amounts of lipid depositions by oil Red O staining, increased thickness of alveolar septa and inflammatory cell infiltration and cell proliferation by HE staining and immunohistochemical assay.2. Lung epithelial type II cell is possiblely involved in the pathologic change of high cholesterol diet caused lung remodeling.