摘要目的:探讨沉默信息调节因子1（SIRT1）调控核因子E2相关因子2（Nrf2）/血红素加氧酶-1（HO-1）信号通路在脓毒症致肝损伤氧化应激和炎症反应中的作用与机制。方法:采用随机数字表法将24只雄性SD大鼠分为假手术（Sham）组、盲肠结扎穿孔术（CLP）组、SIRT1激动剂SRT1720预处理（CLP+SRT1720）组、SIRT1抑制剂EX527预处理（CLP+EX527）组，每组6只。术前2 h分别向CLP+SRT1720组和CLP+EX527组腹腔注射10 mg/kg的SRT1720或EX527。于制模后24 h腹主动脉取血并处死大鼠取肝脏组织，用酶联免疫吸附试验（ELISA）检测血清中白细胞介素（IL-6、IL-1β）和肿瘤坏死因子-α（TNF-α）水平；用微板法检测血清丙氨酸转氨酶（ALT）和天冬氨酸转氨酶（AST）水平；用苏木素-伊红（HE）染色观察各组大鼠病理损伤情况；使用相应试剂盒分别检测肝组织丙二醛（MDA）、8-羟基脱氧鸟苷（8-OHdG）、谷胱甘肽（GSH）含量及超氧化物歧化酶（SOD）活性；采用实时荧光定量聚合酶链反应（RT-qPCR）和蛋白质免疫印迹试验（Western blotting）检测肝组织SIRT1、Nrf2、HO-1的mRNA及蛋白表达。结果:与Sham组比较，CLP组血清IL-6、IL-1β、TNF-α、ALT、AST水平明显升高；组织病理学结果显示肝索排列紊乱，肝细胞肿胀坏死，出现大量炎症细胞浸润；肝组织中MDA、8-OHdG含量升高，GSH含量及SOD活性降低，SIRT1、Nrf2、HO-1的mRNA及蛋白表达水平明显下降，提示脓毒症大鼠出现肝功能障碍，肝组织内SIRT1、Nrf2、HO-1以及抗氧化蛋白水平降低，而氧化应激和炎症水平升高。与CLP组比较，CLP+SRT1720组大鼠炎症因子和氧化应激水平明显降低，SIRT1、Nrf2、HO-1的mRNA及蛋白表达水平显著升高〔IL-6（ng/L）：34.59±4.21比61.84±3.78，IL-1β（ng/L）：41.37±2.70比72.06±3.14，TNF-α（ng/L）：76.43±5.23比130.85±5.30，ALT（U/L）：30.71±3.63比64.23±4.59，AST（U/L）：94.57±6.08比145.15±6.86，MDA（μmol/g）：6.11±0.28比9.23±0.29，8-OHdG（ng/L）：117.43±10.38比242.37±11.71，GSH（μmol/g）：11.93±0.88比7.66±0.47，SOD（kU/g）：121.58±5.05比83.57±4.84，SIRT1 mRNA（2 -ΔΔCt）：1.20±0.13比0.46±0.02，Nrf2 mRNA（2 -ΔΔCt）：1.21±0.12比0.58±0.03，HO-1 mRNA（2 -ΔΔCt）：1.71±0.06比0.48±0.07，SIRT1蛋白（SIRT1/β-actin）：0.89±0.04比0.58±0.03，Nrf2蛋白（Nrf2/β-actin）：0.87±0.08比0.51±0.09，HO-1蛋白（HO-1/β-actin）：0.93±0.14比0.54±0.12，均 P<0.05〕，说明给予SIRT1激动剂SRT1720预处理可改善脓毒症大鼠的肝损伤；但是给予SIRT1抑制剂EX527预处理后则发挥相反的作用〔IL-6（ng/L）：81.05±6.47比61.84±3.78，IL-1β（ng/L）：93.89±5.83比72.06±3.14，TNF-α（ng/L）：177.67±5.12比130.85±5.30，ALT（U/L）：89.33±9.52比64.23±4.59，AST（U/L）：179.59±6.44比145.15±6.86，MDA（μmol/g）：11.39±0.51比9.23±0.29，8-OHdG（ng/L）：328.83±11.26比242.37±11.71，GSH（μmol/g）：5.07±0.34比7.66±0.47，SOD（kU/g）：59.37±4.28比83.57±4.84，SIRT1 mRNA（2 -ΔΔCt）：0.34±0.03比0.46±0.02，Nrf2 mRNA（2 -ΔΔCt）：0.46±0.04比0.58±0.03，HO-1 mRNA（2 -ΔΔCt）：0.21±0.03比0.48±0.07，SIRT1蛋白（SIRT1/β-actin）：0.47±0.04比0.58±0.03，Nrf2蛋白（Nrf2/β-actin）：0.32±0.07比0.51±0.09，HO-1蛋白（HO-1/β-actin）：0.19±0.09比0.54±0.12，均 P<0.05〕。 结论:SIRT1可以通过激活Nrf2/HO-1信号通路来抑制促炎因子的释放，缓解肝细胞氧化损伤，从而对CLP引起的肝损伤起到保护作用。

abstractsObjective:To investigate the role and mechanism of silent information regulator 1 (SIRT1) in regulating nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway in oxidative stress and inflammatory response to sepsis-induced liver injury.Methods:A total of 24 male Sprague-Dawley (SD) rats were randomly divided into sham operation (Sham) group, cecal ligation and puncture (CLP) group, SIRT1 agonist SRT1720 pretreatment (CLP+SRT1720) group and SIRT1 inhibitor EX527 pretreatment (CLP+EX527) group, with 6 rats in each group. Two hours before operation, SRT1720 (10 mg/kg) or EX527 (10 mg/kg) were intraperitoneally injected into the CLP+SRT1720 group and CLP+EX527 group, respectively. Blood was collected from the abdominal aorta at 24 hours after modeling and the rats were sacrificed for liver tissue. The serum levels of interleukins (IL-6, IL-1β) and tumor necrosis factor-α (TNF-α) were detected by enzyme-linked immunosorbent assay (ELISA). The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were detected by microplate method. Hematoxylin-eosin (HE) staining was used to observe the pathological injury of rats in each group. The levels of malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), glutathione (GSH) and superoxide dismutase (SOD) in liver tissue were detected by corresponding kits. The mRNA and protein expressions of SIRT1, Nrf2 and HO-1 in liver tissues were detected by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting.Results:Compared with the Sham group, the serum levels of IL-6, IL-1β, TNF-α, ALT and AST in the CLP group were significantly increased; histopathological results showed that liver cords were disordered, hepatocytes were swollen and necrotic, and a large number of inflammatory cells infiltrated; the contents of MDA and 8-OHdG in liver tissue increased, while the contents of GSH and SOD decreased; and the mRNA and protein expressions of SIRT1, Nrf2 and HO-1 in liver tissues were significantly decreased. These results suggest that sepsis rats have liver dysfunction, and the levels of SIRT1, Nrf2, HO-1 and antioxidant protein in liver tissues were decreased, while the levels of oxidative stress and inflammation were increased. Compared with the CLP group, the levels of inflammatory factors and oxidative stress were significantly decreased in the CLP+SRT1720 group, the mRNA and protein expressions of SIRT1, Nrf2 and HO-1 were significantly increased [IL-6 (ng/L): 34.59±4.21 vs. 61.84±3.78, IL-1β (ng/L): 41.37±2.70 vs. 72.06±3.14, TNF-α (ng/L): 76.43±5.23 vs. 130.85±5.30, ALT (U/L): 30.71±3.63 vs. 64.23±4.59, AST (U/L): 94.57±6.08 vs. 145.15±6.86, MDA (μmol/g): 6.11±0.28 vs. 9.23±0.29, 8-OHdG (ng/L): 117.43±10.38 vs. 242.37±11.71, GSH (μmol/g): 11.93±0.88 vs. 7.66±0.47, SOD (kU/g): 121.58±5.05 vs. 83.57±4.84, SIRT1 mRNA (2 -ΔΔCt): 1.20±0.13 vs. 0.46±0.02, Nrf2 mRNA (2 -ΔΔCt): 1.21±0.12 vs. 0.58±0.03, HO-1 mRNA (2 -ΔΔCt): 1.71±0.06 vs. 0.48±0.07, SIRT1 protein (SIRT1/β-actin): 0.89±0.04 vs. 0.58±0.03, Nrf2 protein (Nrf2/β-actin): 0.87±0.08 vs. 0.51±0.09, HO-1 protein (HO-1/β-actin): 0.93±0.14 vs. 0.54±0.12, all P < 0.05], these results indicated that SIRT1 agonist SRT1720 pretreatment could improve liver injury in sepsis rats. However, pretreatment with SIRT1 inhibitor EX527 showed the opposite effect [IL-6 (ng/L): 81.05±6.47 vs. 61.84±3.78, IL-1β (ng/L): 93.89±5.83 vs. 72.06±3.14, TNF-α (ng/L): 177.67±5.12 vs. 130.85±5.30, ALT (U/L): 89.33±9.52 vs. 64.23±4.59, AST (U/L): 179.59±6.44 vs. 145.15±6.86, MDA (μmol/g): 11.39±0.51 vs. 9.23±0.29, 8-OHdG (ng/L): 328.83±11.26 vs. 242.37±11.71, GSH (μmol/g): 5.07±0.34 vs. 7.66±0.47, SOD (kU/g): 59.37±4.28 vs. 83.57±4.84, SIRT1 mRNA (2 -ΔΔCt): 0.34±0.03 vs. 0.46±0.02, Nrf2 mRNA (2 -ΔΔCt): 0.46±0.04 vs. 0.58±0.03, HO-1 mRNA (2 -ΔΔCt): 0.21±0.03 vs. 0.48±0.07, SIRT1 protein (SIRT1/β-actin): 0.47±0.04 vs. 0.58±0.03, Nrf2 protein (Nrf2/β-actin): 0.32±0.07 vs. 0.51±0.09, HO-1 protein (HO-1/β-actin): 0.19±0.09 vs. 0.54±0.12, all P < 0.05]. Conclusion:SIRT1 can inhibit the release of proinflammatory factors and alleviate the oxidative damage of hepatocytes by activating Nrf2/HO-1 signaling pathway, thus playing a protective role against CLP-induced liver injury.