不同剂量X射线诱导小鼠肝损伤中氧化应激水平及其与核因子-κB和转化生长因子-β1的相关性

Oxidative stress and its correlation with nuclear factor-κB and transforming growth factor-β1 in liver injury induced by different doses of X-rays in mice

[背景]放射性肝损伤是原发性肝癌和其他上腹部肿瘤放射治疗过程中的主要并发症,目前关于不同剂量辐射诱导放射性肝损伤的早期生物学效应及其作用机制尚未阐明。[目的]建立不同剂量X射线诱导小鼠放射性肝损伤模型,探讨不同剂量X射线诱导肝损伤中氧化应激水平及其与核因子-κB(NF-κB)和转化生长因子-β1(TGF-β1)的相关性。[方法]将24只6周龄雄性C57BL/6J小鼠随机分为对照组、0.8 Gy组、1.6 Gy组、4 Gy组,每组6只。采用X射线对各剂量组小鼠进行全身单次辐照。辐射后24 h,检测小鼠肝脏组织病理学变化;测定小鼠外周血细胞计数、血清中谷草转氨酶和谷丙转氨酶水平;检测肝脏组织超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量、还原型谷胱甘肽(GSH)含量和8-羟基脱氧鸟苷(8-OHdG)的水平;采用实时荧光定量PCR检测肝脏组织NF-κB p65、TGF-β1 mRNA表达水平;采用Pearson相关分析氧化应激相关指标与NF-κB p65、TGF-β1 mRNA表达水平的相关性。[结果]与对照组相比,不同剂量X射线辐射后24 h:小鼠肝脏组织病理学观察到早期损伤变化,4 Gy组小鼠血清中谷草转氨酶和谷丙转氨酶水平升高(P<0.05);各辐射组小鼠外周血白细胞、淋巴细胞均下降(P<0.05),且呈现随辐射剂量增加而降低的趋势;各辐射组小鼠肝脏中氧化应激指标(MDA、SOD、GSH)水平均升高(P<0.05),且呈现随着辐射剂量的增加而升高的趋势。分别与对照组和0.8 Gy组相比,1.6 Gy组、4 Gy组小鼠肝脏8-OHdG水平均升高(P<0.05)。与对照组相比,1.6 Gy组、4 Gy组小鼠肝脏NF-κB p65、TGF-β1 mRNA表达水平均升高(P<0.05),其中TGF-β1 mRNA表达水平随辐射剂量的增加呈现逐渐升高的趋势。相关分析显示,各组小鼠肝脏组织中MDA、SOD、GSH、8-OHdG水平与NF-κB p65、TGF-β1 mRNA表达水平呈正相关(P<0.05)。[结论]不同剂量X射线辐射可影响小鼠肝损伤程度、外周血细胞计数、血清谷草转氨酶和谷丙转氨酶水平、肝脏氧化应激水平。由X射线诱导的肝脏组织的氧化应激水平与肝脏组织NF-κB及TGF-β1具有相关性,可能参与放射性肝损伤作用过程。

[Background] Radiation-induced liver damage is a major complication for primary liver cancer and other upper abdominal tumors during radiation therapy. The early biological effects of radiation-induced liver damage at different doses of radiation and its mechanisms of action have not yet been elucidated.[Objective] To establish X-ray-induced radioactive mouse liver damage model and explore the level of oxidative stress and its correlation with nuclear factor-κB(NF-κB) and transforming growth factor-β1(TGF-β1).[Methods] A total of 24 male C57BL/6J mice aged 6 weeks were randomly divided into 4 groups(control, 0.8 Gy, 1.6 Gy, and 4 Gy), with 6 mice in each group. X-rays irradiated the whole body of mice singly in each dose group. At 24 h after radiation, histopathological changes in mouse liver were evaluated;peripheral blood cell count, serum aspartate aminotransferase(AST) and alanine aminotransferase(ALT)levels, as well as liver tissue superoxide dismutase(SOD) activity, malondialdehyde(MDA) level, reduced glutathione(GSH) level, and 8-hydroxy-2′-deoxyguanosine(8-OHd G) level were measured;real-time fluorescence quantitative PCR was used to detect liver tissue NF-κB p65 and TGF-β1 mRNA expression levels;the correlations of oxidative stress indicators with NF-κB p65 and TGF-β1 mRNA expression levels were analyzed by Pearson correlation.[Results] Compared with the control group, at 24 h after different doses of X-ray radiation, early injury-related histopathological changes were observed in liver, and the serum levels of AST and ALT were significantly increased in the 4 Gy group(P < 0.05);the numbers of peripheral blood leukocytes and lymphocytes were decreased in the radiation exposure groups(P < 0.05), showing a decreasing trend with increasing radiation doses;the levels of liver oxidative stress indicators(MDA, SOD, and GSH) in exposed mice were significantly increased(P < 0.05), showing an increasing trend with increasing radiation doses. The liver 8-OHd G were significantly increased in the 1.6 Gy and 4Gy groups compared with the control and the 0.8 Gy groups, respectively(P < 0.05). The NF-κB p65 and TGF-β1 mRNA expression levels in the liver of mice were significantly increased in the 1.6 Gy and 4 Gy groups compared with the control group(P < 0.05). The TGF-β1mRNA expression level also exhibited an increasing trend with increasing radiation doses. The results of correlation analysis showed that the levels of MDA, SOD, GSH, and 8-OHd G in liver tissues were significantly and positively correlated with the expression levels of NF-κB p65 and TGF-β1 mRNA(P < 0.05).[Conclusion] X-rays of various doses can affect the degree of liver injury, peripheral blood cell count, serum levels of AST and ALT, and liver oxidative stress levels in mice. The level of oxidative stress induced by X-ray is positively correlated with NF-κB and TGF-β1 in liver tissues, and it may participate in the process of radiation-induced liver injury.