Experimental studies on the protective effects of the overexpression of lentivirus-mediated sirtuin 6 on radiation-induced lung injury.

Background. Sirtuin 6 (SIRT6) can increase the radiosensitivity of non-small cell lung cancer and exert protective effects on radiation-induced lung injury. Objectives. To investigate protective effects of SIRT6 overexpression on radiation-induced lung injury in rats. Material and methods. Male Wistar rats (n = 72) were randomly divided into 3 groups. Models were made by radiating both lungs with a 6MV 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 (the Lent-SIRT6 group) on the same day as the modeling. Routine blood indexes (white blood cells (WBC), red blood cells (RBC), neutrophils and lymphocytes) were recorded; the rats were sacrificed and their lung tissues taken; pathological changes in the lungs were evaluated using hematoxylin and eosin (H&E) staining; and tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6) and interleukin 1 beta (IL-1 beta) were detected with enzyme-linked immunosorbent assay (ELISA) 8 weeks after radiotherapy. Results. The lung structure including alveolar walls and interstitium in the control group was normal, but the alveolar walls in the radiation group were obviously thickened and a large a mount of hyperplastic fibrous tissue was found in the alveolar interstitium. The thickness and interstitial fibrosis of the alveolar walls were more alleviated in the Lent-SIRT6 group than in the radiation group. Compared with those in the control group, the respiratory rates, levels of TNF-a and IL-6 in serum, neutrophils and levels of TNF-alpha, IL-6 and IL-1 beta in the liver all were increased, while WBC5 and lymphocytes were decreased in the radiation group. The respiratory rates, levels of TNF-alpha and IL-6 in serum, neutrophils and levels of TNF-alpha, IL-6 and IL-1 beta in the liver were all decreased, and WBC5 and lymphocytes were increased after injection with lentivirus carrying overexpressed SIRT6. Conclusions. Sirtuin 6 inhibits inflammation and alleviates radioactive pneumonia and lung injury. Therefore, SIRT6 can exert certain protective effects on lung injury.