高尿酸对大鼠肾小球足细胞的损害作用

The effect of hyperuricemia on glomerular podocyte in rates and its mechanisms

目的:探讨高尿酸对大鼠足细胞的损害作用及其可能机制。方法:40只雄性SD大鼠随机平均分为4组,即对照组、轻微高尿酸组、高尿酸组、别嘌醇干预组。饲养24周后处死大鼠,心脏取血检测肌酐、尿酸水平,左肾切除后行病理检查,并检测血管紧张素Ⅱ(AngⅡ)、白细胞介素6(IL-6)、超氧化物歧化酶(SOD)、nephrin、podocin在肾组织中的表达情况。结果:各组大鼠血肌酐水平差异无统计学意义;对照组、轻微高尿酸组、高尿酸组、别嘌醇干预组血尿酸水平分别为(65.04±5.26)、(106.87±11.00)、(147.23±25.75)、(89.78±11.67)μmol/L,每两组间差异有统计学意义(P<0.05)。苏木精-伊红(H-E)染色显示轻微高尿酸组、高尿酸组肾小球系膜区有核细胞数略增多,但各组大鼠肾组织病理学改变均不明显。电镜显示:轻微高尿酸组、高尿酸组存在不同程度足突融合及足突细胞病理改变。免疫组化染色显示:AngⅡ主要表达于肾小球系膜区,少量表达于肾小管上皮细胞,组间差异有统计学意义(P<0.05);IL-6主要表达于肾小管上皮细胞,少量表达于肾小球,组间差异有统计学意义(P<0.05);SOD在肾小球及小管内均表达,组间差异有统计学意义(P<0.05)。Western印迹及RT-PCR显示,每两组大鼠肾组织nephrin、podocin蛋白及mRNA表达差异均有统计学意义(P<0.05)。血尿酸水平与肾组织nephrin、podocin、SOD表达负相关(P<0.05),与肾组织AngⅡ及IL-6的表达正相关(P<0.05);肾组织AngⅡ、IL-6的表达与nephrin、podocin的表达负相关(P<0.05);肾组织SOD的表达与nephrin、podocin的表达正相关(P<0.05)。结论:高尿酸血症可导致肾小球足细胞病变,其可能机制包括诱发氧化应激、激活RAS系统及微炎症反应;别嘌醇可通过降低血尿酸水平或通过减轻氧化应激反应、调控RAS活性及微炎症反应来减轻足细胞损伤。

Objective:To investigate the effect of hyperuricemia on podocyte and its possible mechanisms.Methods:A total of 40 male SD rats were randomly divided into four groups,including control group(group A),mild hyperuricemia group(group B),hyperuricemia group(group C),and allopurinol group(group D).Twenty-four weeks later,all rats were sacrificed,and heart blood was taken for detecting creatinine and uric acid.The left kidneys were collected for pathological examination,as well as detection of the expression levels of angiotensinⅡ(AngⅡ),interleukin-6(IL-6),superoxide dismutase(SOD),nephrin,podocin using immunohistochemical staining,Western blotting,and RT-PCR.Results:There were no obvious differences in Scr levels among the four group,while the levels of uric acid in groups A,B,C,and D were(65.04±5.26),(106.87±11.00),(147.23±25.75),and(89.78±11.67)μmol/L,and significant differences statistically were found between either two of the four groups.No obvious renal histopathological abnormalities were observed by H-E staining in all four groups.The number of nucleated cells in the glomerular mesangial area was slightly higher in group B and C.Different degrees of podocytopenia and pathological changes of podocytes were also observed in group B and C using electron microscope.Immunohistochemical staining showed that AngⅡwas mainly expressed in the glomerular mesangial area and a few in the renal tubular epithelial cells,and the differences of the AngⅡexpression were statistically significant between either two groups(P<0.05).IL-6 was mainly expressed in renal tubular epithelial cells and a few in the glomerular mesangial area,and the differences of the IL-6 expression were statistically significant between either two groups(P<0.05).SOD was expressed in glomerular and tubular cells,the differences of the SOD expressions were statistically significant between either two groups(P<0.05).Western blotting and real-time PCR results showed that the levels of protein and mRNA of nephrin and podocin in the renal tissues were different between either two groups(P<0.05).Correlation analysis showed that there were negative correlations between serum uric acid and the expression of nephrin,podocin,SOD in kidney tissue,and there were positive correlations between serum uric acid and the expression of AngⅡand IL-6 in kidney tissue(P<0.05).There were negative correlations between the expression levels of AngⅡ,IL-6,nephrin,and podocin in kidney tissue(P<0.05).There were positive correlations between the expression levels of SOD,nephrin and podocin in kidney tissue(P<0.05).Conclusions:Hyperuricemia can lead to podocytes injury,and the probable mechanisms include activation of the RAS system,oxidative stress,micro-inflammatory response.Allopurinol could reduce the podocyte injury through lowering uric acid or lowering the activation of the RAS system,oxidative stress,and micro-inflammatory response.