p38 MAPK在大鼠梗阻性肾病肾组织中的表达及可能作用

目的：探讨p38 MAPK在大鼠梗阻性肾病模型肾组织中的表达及其在肾脏纤维化发病机制中的作用。方法：采用单侧输尿管结扎制造梗阻性肾病模型，分别于造模后1 h、3 h、6 h、12 h、1 d、3 d、5 d、7 d、14 d、21 d、28 d取肾组织，应用免疫沉淀结合特异性底物磷酸化法测定肾组织p38 MAPK活性，用免疫组织化学法检测磷酸化p38 MAPK在肾组织中的表达；用免疫组织化学及原位杂交方法检测肾组织TGFβ₁ mRNA和蛋白水平的表达。结果：正常对照组大鼠肾组织有一定的p38 MAPK基础活性（吸光度A值）(0.22±0.06)。UUO术后1 h，p38 MAPK即被激活（0.45±0.14 vs 对照组，P<0.05），12 h时达第一个高峰（0.91±0.07 vs 对照组，P<0.01），此后活性逐渐下降，3 d后又进行性升高，7 d达到第二个高峰（0.93±0.06 vs 对照组，P<0.01），此后又缓慢下降，28 d降至最低水平(0.12±0.02)。而TGFβ₁的表达在UUO术后1 h、3 h、6 h、12 h及24 h无明显增加，第3 d有明显增加（13.55%±6.33% vs 对照组，P＜0.05），第7 d达高峰（26.78%±8.77% vs 对照组，P<0.01），第28 d表达最少。梗阻肾肾组织p38 MAPK的激活明显早于TGFβ₁表达且p38 MAPK早期活性水平与TGFβ₁的表达水平呈正相关；梗阻肾高表达的TGFβ₁与肾组织p38MAPK的后期活性的高低显著相关（r=0.84, P<0.01）。结论：p38 MAPK在大鼠梗阻性肾病肾组织中的活性明显增高，可能介导梗阻肾肾组织TGFβ₁的表达，并可能参与TGFβ₁诱导的肾间质纤维化的过程。

Expression and functional role of p38MAPK in the kidney after unilateral ureteral obstruction in rats

AIM: To investigate the expression and functional role of p38MAPK in the kidney after unilateral ureteral obstruction in rats. METHODS: Unilateral ureteral obstruction (UUO) models were induced by ligating the left ureter. Rats were sacrificed at 1 h, 3 h, 6 h, 12 h, 1, 3, 5, 7, 14, 21, and 28 days after UUO was initiated. p38MAPK activity was assayed by immunohistochemical staining and specific substrate phosphorylation with immunoprecipitation and Western blotting. TGFβ mRNA and protein expression were analyzed with in situ hybridization and immunohistochemical stainning. RESULTS: A basic p38MAPK activity was detectable in the normal kidney(0.22±0.06).p38MAPK pathway was rapidly act ivated at 1 hour(0.45±0.14 vs control,P<0.05)and this was steadily in creased by 12 hours(0.91±0.07 vs control,P<0.01)after UUO.Afterwards,the activity of p38MAPK reduced grad ually,then increased again from 3 days and this was steadily increased by 7 days(0.93±0.06 vs control,P<0.01). Upregulation of TGFβ₁ was markedly tested at 3 days(13.55±6.33 vs control,P<0.05)and this was steadily in creased by 7 days(26.78 8.77 vs control,P<0.01).The activation of p38MAPK preceded markedly the expression of TGF 1.The early activity of p38 MAPK was positively related to the amount of TGFβ₁ expression.The amount of TGFβ₁ expressed in obstructed kidney also related significant ly to the late activity of p38MAPK(r=0.84,P<0.01). CONCLUSION: The activity of p38MAPK is increased significantly in the obstructed kidney, which may cause renal fibrosis via inducing the expression of TGFβ₁.