霉酚酸酯对蛋白超载肾病大鼠p38丝裂素活化蛋白激酶信号转导通路的影响

目的 探讨霉酚酸酯(MMF)对蛋白超载肾病大鼠p38丝裂素活化蛋白激酶(p38MAPK)信号转导通路的影响.方法 SD大鼠30只分3组(n=10):对照组(生理盐水)、BSA组[牛血清白蛋白(BSA)超载肾病大鼠]、治疗组(BSA+MMF).采用蛋白超载肾病大鼠模型,于4周后观察各组大鼠尿素氮(BUN)、血肌酐(Scr)、24h尿蛋白定量;免疫组织化学检测核因子κB(NF-κB),应用凝胶迁移率变动分析检测NF-κB的活性变化;Western免疫印迹分析法检测p38 MAPK的磷酸化水平.光镜和电镜观察大鼠肾组织形态改变.结果 光镜和电镜显示BSA组大鼠出现肾间质淋巴、单核细胞浸润、肾小管萎缩和纤维化等病变;治疗组病变较BSA组明显减轻.与对照组比较,BSA组大鼠24 h尿蛋白增加[(48.3±3.3)mg/24h比(67.8±4.5)mg/24 h,P<0.05],NF-κB和p38 MAPK表达增加(45.24±6.25比88.59±7.43和80.68±8.34比235.23±10.41,P<0.05),且p38 MAPK表达与NF-κB和24h尿蛋白定量呈正相关(r=0.72,r=0.65,P<0.05).与BSA组比较,治疗组MMF可减少尿蛋白排泄[(59.1±4.2)mg/24 h,P<0.05],同时抑制p38 MAPK磷酸化和NF-κB的表达(P<0.05).结论 MMF可减少NF-κB的表达,其机制可能依赖于抑制p38 MAPK的磷酸化.

Effect of mycophenolate mofetil on the expression of p38 mitogen-activated protein kinase signal pathway in protein-overload rats

Objective To investigate the effect of mycophenolate mofetil (MMF) on the expression of p38 mitogen- activated protein kinase (MAPK) signal pathway in protein- overload nephrotic rats. Methods Thirty SD rats were divided into three groups (n=10 each): control group (normal saline), BSA group [protein-overload nephrotic rats, bovine serum albumin (BSA) group] and treatment group (BSA+ MMF). The protein-overload nephrotic rats were used. After 4 weeks, urinary proteins in 24 h, blood urea nitrogen (BUN) and serum creatinine were measured. Immunhistochemistry was applied to measure the expression of NF-κB. The activity of NF-κB was determined by electrophoretic mobility shift assay (EMSA). Western blot was performed to determine p38 MAPK protein. Renal tissues were examined by light microscopy and electron microscopy. Results The histological changes of BSA group showed tubular atrophy, widening of intertubular spaces with increased lymphocytes and mononuelear cells infiltration and fibrosis. Such histological changes were obriously improved in treatment group. Compared with the control group, urinary protein [(48.3±3.3) mg/24 h vs (67.8±4.5)mg/24 h, P<0.05], expression of NF-κB and p38 MAPK (45.24±6.25 vs 88.59±7.43; 80.68±8.34 vs 235.23±10.41) were significantly increased in protein-overload nephrotic rats (P<0.05). There were positive correlations of p38 MAPK with NF-κB and urinary protein (r=0.72, r=0.65, P<0.05). Compared with BSA group, MMF inhibited the expression of p38 MAPK, NF-κB and partly decreased the level of urinary protein [(59.1±4.2) mg/24 h,P<0.05]. Conclusion MMF can inhibit the expression of NF-κB and its mechanism may be due to the inhibition of p38 MAPK phosphorylation.