SIRTl在小鼠肾缺血再灌注损伤中的作用及其对NF-κBp65-PGC-1α信号通路的影响

Role of SIRT1 in renal ischemia- reperfusion injury and its effect on NF- KBp65 - PGC- 1α signal pathway in mice

目的研究沉默信息调节因子2相关酶类1（SIRT1）在小鼠肾缺血再灌注（IR）损伤中的作用及其对NF-κBp65-过氧化物酶体增殖物激活受体γ辅激活因子1α（PGC-1α）信号通路的影响。方法将72只健康雄性C57BL／6小鼠按随机数字法分成4组，正常对照组（Con组，n=18）、假手术组（Sham组，n=18）、IR组（n=18）、白藜芦醇干预组（Res组，n=18），采用双侧肾蒂夹闭45min建立急性缺血性肾损伤模型，建模前每天给予2％二甲亚砜或者白藜芦醇（10mg·kg^-1·d^-1），腹腔注射7d。常规生化法检测Scr、BUN水平，分光光度法测定肾脏组织中超氧化物歧化酶（SOD）含量，HE染色法观察肾组织学改变，免疫组织化学法、Western印迹法检测肾组织SIRT1、NF．KBp65、PGC-101的表达。结果于再灌注12h开始，IR组血清Scr和BUN高于Con组和Sham组（均P〈0．05），Res组上述指标低于同期IR组（均P〈0．05）；IR组肾组织SOD水平低于Con组和Sham组（均P〈0．05），至24h时Res组SOD水平高于IR组（P〈0．05）。HE染色显示，IR组肾脏存在不同程度的肾小管上皮细胞坏死等病理损害，而Res组病理损伤减轻。Western印迹结果显示肾脏缺血再灌注后SIRT1的表达升高，NF-κB信号通路被激活，p65的表达升高，PGC-1α的表达降低，与Con组和Sham组相比差异均有统计学意义（均P〈0．05）。Western印迹和免疫组化结果均显示，再灌注24h后，Res组SIRTl、PGC-1α的表达高于IR组（均P〈0．05），而Res组NF-κBp65的表达低于IR组（P〈0．05）。结论在小鼠肾缺血再灌注模型中，激动SIRT1可以抑制NF-κBp65的表达，从而上调PGC-1α水平，减轻炎性反应和氧化应激损伤，对肾脏起到保护作用。

Objective To investigate the role of silent mating type information regulation 2 homologue 1（SIRT1） in renal ischemia-reperfusion（IR） injury and its effect on NF-KBp65 - peroxisome proliferator-activated receptor gamma eoactivator 1 alpha （PGC-1α） signal pathway in mice. Methods Seventy- two healthy C57BL/6 male mice were randomly divided into four groups： control group（n= 18）, sham-operated group（n=18）, IR group（n=18）, resveratrel group（n=18）. Bilateral renal pedicle were clamped for 45 min was adopted to establish the model of acute ischemic renal injury, to give 2% dimethyl sulfoxide or resveratrol by intraperitoneal injection for 7 days before modeling. Determination techniques included routine biochemical methods for the the levels of Scr and BUN, spectrophotometryfor the level of superoxide dismutase （SOD）, HE staining for the histological changes as well as immunohistochemical method and Western blotting for the expressions of SIRT1, NF-κBp65 and PGC- 1α, respectively. Results Compared with that in control and sham-operated groups, the levels of serum Scr and BUN were higher and SOD levels in renal tissues were lower at 12 h and 24 h after operation in IR groups（P 〈 0.05）. liE staining revealed evident pathological lesions including necrosis of renal tubular epithelial cells in IR group. Compared with that in IR group, resveratrol attenuated the abovementioned changes. Western blotting revealed the upregulated SIRT1 expression and the activated NF-κB signal pathway, the up-regulated p65 expression and the down-regulated PGC-let expression subsequent to IR（P 〈 0.05）. Both Western blotting and immunohistochemistry showed that the expressions of SIRT1 and PGC-let in resveratrol group were up-regulated compared to that in IR group（P 〈 0.05）, while the NF- KBp65 expression in resveratrol group was down- regulated（P 〈 0.05）. Conclusions In mouse model of renal ischemia- reperfusion injury, the activation of SIRT1 can inhibit the NF- κBp65 expression and accordingly upregulated PGC- 1α level, contributing to inhibiting inflammatory reactions and attenuating oxidative stressinduced injury in the protection of the kidneys.