炎症通过SCAP-SREBP2-LDLr途径促进四氯化碳诱导的小鼠脂肪变肝细胞胆固醇内流  

Inflammatory stress exacerbates cholesterol import in fatty liver of CCl_4-induced mice via LDLr-SREBP-2-SCAP pathway

作　　者：田琳[1] 刘宏[2] 谢友红[3] 

机构地区：[1]重庆医科大学附属第一医院消化内科,重庆400016 [2]重庆医科大学附属第一医院生殖健康与不孕专科,重庆400016 [3]重庆医科大学附属大学城医院消化中心,重庆401331

出　　处：《第三军医大学学报》2014年第11期1158-1162,共5页Journal of Third Military Medical University

基　　金：重庆市卫生局面上项目(2009-2-312)~~

摘　　要：目的 探讨炎症促进CCl4所致的单纯性脂肪变肝细胞进一步脂质集聚形成脂肪肝的分子机制。 方法 将12只6~8周龄的 C57BL/6J雄性小鼠采用随机数字表法分为对照组（n=6）和炎症组（n=6）。2组均预先皮下注射CCl4 2周，再分别给予对照组和炎症组生理盐水和酪蛋白皮下注射16周，18周后留取小鼠血清及肝组织，检测血清炎症因子及脂质水平，HE及油红O染色观察小鼠脂肪肝病变程度，RT-PCR、免疫组化及Western blot分别检测小鼠肝组织的低密度脂蛋白受体（low-density lipoprotein receptor，LDLr）、固醇调节元件结合蛋白-2（sterol regulatory element binding protein 2,SREBP-2）和SREBP裂解激活蛋白（SREBP cleavage activating protein，SCAP）的基因和蛋白表达水平。 结果 炎症组的血清淀粉样蛋白（serum amyloid A,SAA）和TNF-α的表达均较对照组明显升高[分别为（236.09±38.45）ng/mL vs （35.68±11.34）ng/mL,（82.59±11.48）pg/mL vs （17.91±2.77）pg/mL,P〈0.05]，炎症组的血清HDL-c、LDL-c、TC均较对照组明显降低[分别为（0.91±0.10）vs（1.80±0.12）mmol/L,（2.65±0.44）vs（5.76±0.33）mmol/L,（3.69±0.26）vs（4.16±0.22）mmol/L,P〈0.05],HE及油红O染色显示炎症组可见大量的脂质堆积。炎症组的LDLr、SREBP-2、SCAP的mRNA和蛋白表达比对照组明显增高（P〈0.05）。 结论 炎症可能通过上调肝细胞LDLr、SREBP-2、SCAP的表达，导致CCl4刺激下的脂肪变肝细胞摄入外源性胆固醇增加，加重肝脏脂质的异常集聚。Objective To investigate the molecular mechanism of inflammatory stress promoting the simple steatosis caused by carbon tetrachloride （CCl4） to further lipid accumulation. Methods A total of 12 male C57BL/6J mice at 6 to 8 weeks were randomly divided into control group （n=6） and inflammation group （n=6）. In 2 weeks after subcutaneous treatment of CCl4, the animals from control and inflammation groups were given normal saline and casein respectively by subcutaneous injection for 16 weeks. At the end of the treatment, the blood sample and liver tissue of the mice were collected. Serum levels of lipids were detected by enzymatic assay. Inflammatory cytokines, such as serum amyloid A （SAA） and tumor necrosis factor-α （TNF-α） were determined by ELISA. Lipid accumulation in the liver was evaluated by HE staining and oil red O staining. The expression of low-density lipoprotein receptor （LDLr）, sterol regulatory element binding protein-2 （SREBP-2） and SREBP cleavage activating protein （SCAP） at mRNA and protein levels were analyzed by real-time polymerase chain reaction （RT-PCR）, immunohistochemistry staining and Western blotting respectively. Results The serum levels of SAA and TNF-α were significantly higher in inflammation group than in the control group （236.09±38.45 vs 35.68±11.34 ng/mL,82.59±11.48 vs 17.91±2.77 pg/mL, both P〈0.05）. Casein treatment resulted in significantly declines in the serum levels of HDL-c, LDL-c and TC when compared with the control group （0.91±0.10 vs 1.80±0.12 mmol/L, 2.65±0.44 vs 5.76±0.33 mmol/L, 3.69±0.26 vs 4.16±0.22 mmol/L, all P〈0.05）. HE staining and oil red O staining indicated that a lot of lipid accumulation were observed in the liver of mice in inflammation group. The mRNA and protein expression levels of LDLr, SREBP-2 and SCAP were significantly increased in inflammation group than in control mice （P〈0.05）. Conclusion Inflammation may exacerbate lipid accumulation via up-regulating the expression of LDLr, SREB

关 键 词：炎症 四氯化碳 SREBP-2 LDLR SCAP 

分 类 号：R363[医药卫生—病理学] R364.5[医药卫生—基础医学]