Experimental studies on the protective effects of the over-expression of lentivirus-mediated SIRT6 on radiation-induced lung injury

Abstract

Objective: To investigate the protective effects of the over-expression of SIRT6 on radiation-induced lung injury in rats. Methods: 72 male Wistar rats (150-120 g) were randomly divided into 3 groups (n=24). Models were made through radiating both lungs with a 6 MV-X linear accelerator. Each group was injected through the tail vein with normal saline (the control group and radiation group) and lentivirus carrying overexpressed SIRT6 (Lent-SIRT6 group) on the exact day of modeling. Changes in respiratory rates, body weight and levels of TNF-α and IL-6 in serum were measured respectively at 1, 2, 4 and 8 weeks after radiation. Blood routine indexes (RBCs, neutrophils and lymphocytes) were recorded, rats were sacrificed with their lung tissues taken, pathological changes of lungs were evaluated by HE staining and TNF-α, IL-6 and IL-1β were detected with ELISA at 8 weeks after radiotherapy. Results: The lung structure including alveolar walls and interstitium in control group were normal, but alveolar walls in radiation group were obviously thickened and a large amount of hyperplastic fibrous tissues were found in alveolar interstitium, while the thickness and interstitial fibrosis of alveolar walls were more alleviated in Lent-SIRT6 group than in radiation group. Compared with those in control group, the respiratory rates, levels of TNF-α and IL-6 in serum, neutrophils and levels of TNF-α, IL-6 and IL-1β in liver all were increased, while WBCs and lymphocytes were decreased in radiation group. The differences were statistically significant (P<0.05). The respiratory rates, levels of TNF-α and IL-6 in serum, neutrophils and levels of TNF-α, IL-6 and IL-1β in liver were all decreased, and WBC and lymphocytes were increased after injection with over-expressed SIRT6. The differences were statistically significant (P<0.05). Conclusion: SIRT6 inhibits inflammation and alleviates radioactive pneumonia and lung injury. Therefore, SIRT6 can exert certain protective effects on lung injury.