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目的探讨肾脏局部肾素血管紧张素系统(RAS)激活在载脂蛋白E基因敲除(ApoE-/-)小鼠高脂介导的肾损伤中的作用。方法将16只8周龄雄性ApoE-/-小鼠适应性喂养1周后随机分为高脂饮食组(n=8)和普通饮食对照组(n=8),8周后处死小鼠收集血浆标本及肾脏组织标本,放射免疫法检测血浆前肾素、肾素、血管紧张素Ⅰ(AngⅠ)、血管紧张素Ⅱ(AngⅡ)水平,临床生化试剂盒检测血浆脂质谱,HE和Masson染色评估肾脏炎症细胞浸润及胞外基质堆积,免疫组化及Westernblot法检测肾脏组织内RAS成分、上皮细胞间充质转分化(EMT)标记蛋白E钙黏蛋白(E-cadherin)和α平滑肌肌动蛋白(α-SMA)的表达,并评估高血脂症、肾脏局部RAS水平与肾脏损伤的相关性。结果与对照组比较,高脂饮食组小鼠血脂水平明显升高[三酰甘油(7.5±2.0)比(3.1±0.6)mmol/L;总胆固醇(27.8±4.0)比(13.7±2.7)mol/L;低密度脂蛋白胆固醇(LDL-C)(11.6±3.0)比(5.8±1.5)mmol/L,均P<0.05],伴有肾小管间质胞外基质堆积增多。血浆肾素、AngⅠ及AngⅡ水平两组间差异无统计学意义,但高脂饮食组血浆前肾素水平明显低于对照组[(1108.6±55.2)比(1881.3±180.4)μg/(L·h),P<0.05]。免疫组化及Westernblot检测均示肾脏局部RAS成分表达升高。局部AngⅡ水平与血浆总胆固醇、三酰甘油和LDL-C水平呈正相关(分别r=0.709、0.758、0.806,均P<0.05),血管紧张素原、AngⅡ、肾素、AngⅡ1型受体(AT1R)和AngⅡ2型受体(AT2R)水平与E-cadherin表达呈负相关(分别r=-0.723、-0.772、-0.754、-0.821、-0.851,均P<0.05),并与α-SMA呈正相关(分别r=0.636、0.842、0.600、0.842、0.770,均P<0.05)。结论高血脂症可诱导EMT、肾小管间质纤维化和促进肾损伤进展,并与肾脏局部RAS激活有关。
Objective To investigate the role of renal renin-angiotensin system (RAS) activation in hyperlipidemic kidney injury induced by apolipoprotein E gene knockout (ApoE - / -) mice. Methods Sixteen 8-week-old male ApoE - / - mice were randomly divided into high fat diet group (n = 8) and normal diet control group (n = 8) Plasma samples and renal tissue samples were collected. Radioimmunoassay was used to detect the levels of plasma renin, renin, angiotensin Ⅰ (AngⅠ) and angiotensin Ⅱ (AngⅡ). The plasma lipid profiles were detected by clinical biochemistry kit. HE and Masson staining Renal infiltration of inflammatory cells and accumulation of extracellular matrix, immunohistochemistry and Western blotting were used to detect the expression of RAS, E-cadherin and α-smooth muscle actin (α-SMA) expression, and to assess hyperlipidemia, renal local RAS levels and renal damage related. Results Compared with the control group, the levels of serum lipids in the high-fat diet group were significantly increased (7.5 ± 2.0 vs 3.1 ± 0.6 mmol / L; the total cholesterol (27.8 ± 4.0) vs (13.7 ± 2.7) mol / / L; LDL-C (11.6 ± 3.0) vs (5.8 ± 1.5) mmol / L, both P <0.05], accompanied with increased accumulation of extracellular matrix of tubulointerstitial tissue. Plasma renin, angiotensin Ⅰ and angiotensin Ⅱ levels were not significantly different between the two groups, but the level of plasma proenzyme in the high-fat diet group was significantly lower than that in the control group [(1108.6 ± 55.2) vs (1881.3 ± 180.4) μg / (L · h ), P <0.05]. Immunohistochemistry and Western blot showed that the expression of renal RAS increased. There was a positive correlation between local AngⅡ level and plasma total cholesterol, triglyceride and LDL-C levels (r = 0.709,0.758,0.806, all P <0.05), angiotensinogen, AngⅡ, renin, AngⅡ1 receptor ) And AngⅡ2 receptor (AT2R) were negatively correlated with the expression of E-cadherin (r = -0.723, -0.772, -0.754, -0.821, -0.851, all P <0.05) (R = 0.636,0.842,0.600,0.842,0.770, respectively, P <0.05). Conclusion Hyperlipidemia can induce EMT, tubulointerstitial fibrosis and promote the progression of renal injury, and is related to renal RAS activation.