1,25-(OH)_2-VD_3下调糖尿病肾病肾脏组织p38MAPK和胶原蛋白的表达

Down-regulation of p38 MAPK and collagen by 1,25-(OH)_2-VD_3 in rat models of diabetic nephropathy

目的研究2型糖尿病肾间质纤维化中p38丝裂原激活蛋白激酶（p38MAPK）、Ⅲ型胶原蛋白（Col3）和Ⅳ型胶原蛋白（Col4）表达，及1，25-（OH）2-VD3对其表达的影响；探讨p38MAPK与Col3和Col4表达的相关性。方法以高糖高脂饮食联合30mg／kg链脲佐菌素（STZ）诱导大鼠2型糖尿病模型。将60只大鼠随机平均分为对照组、模型组、1，25-（OH）2-VD3治疗组[建模后给予6ng／（100g·d）1，25-（OH）2-VD3治疗]、胰岛素组（建模后给予2～3U胰岛素治疗）。干预8周后检测4组血清肌酐（Scr）、血尿素氮（BUN）、24h蛋白尿水平；过碘酸希夫反应（PAS）染色观察肾脏病变情况；采用Western blot及免疫组织化学染色检测大鼠肾间质p38MAPK、CoD和Col4的表达；采用Spearman法进行相关性分析。结果与模型组相比，1，25-（OH）2-VD3治疗组和胰岛素治疗组血清肌酐、尿素氮、24h蛋白尿和肾间质受损面积均降低；与对照相比，模型组p38MAPK、Col3和Col4水平增加，1，25-（OH）2-VD3治疗组和胰岛素治疗组明显降低；相关性分析发现24h蛋白尿与p38MAPK、CoB和Col4免疫组织化学的结果呈正相关，p38MAPK的表达与Col3和Col4表达呈正相关。结论2型糖尿病大鼠肾间质组织p38MAPK、Col3和Col4表达上调，1，25-（OH）2-VD3可能通过p38MAPK下调Col3、Col4的表达改善糖尿病肾病肾组织纤维化。

Objective To investigate the effect of 1, 25-（OH） 2-VD3 on collagen type Ⅲ （Col3）, collagen type IV （Col4） and p38 mitogen-activated protein kinase （p38 MAPK） in rat models of type 2 diabetic nephropathy, and explore the relationships of p38MAPK with CoB and Col4. Methods Rat models of type 2 diabetic nephropathy were induced by streptozocin （ STZ, 30 mg/kg） combined with high-glucose-and-fat diet. Sixty rats were randomly divided into control group, model group, 1,25- （OH） 2-VD3 treatment group [ given 1,25- （OH） 2-VD3 6 ng/（ 100 g ~ d） after modeling ] and insulin group （ given 2-3 U insulin after modeling）. After 8 weeks＇ intervention, serum creatinine （Scr）, blood urea nitrogen （BUN） and 24-hour proteinuria were detected in all groups. Pedodic acid-Schiff （PAS） staining was used to observe the kidney pathological changes, and immunohistochemical staining and Western blotting were performed to determine p38 MAPK CoB and Col4 expressions in rat renal interstitium. Spearman method was applied to the correlation analysis. Results Compared with the model group, blood glucose, Scr, BUN, 24-hour proteinuria and impaired renal interstitial area were all reduced in the 1, 25-（OH） 2-VD3 treatment group and the insulin group. Compared with the control group, the expressions of CoB, Col4 and p38 MAPK were higher in the model group, and lower in the l, 2.5-（OH）2-VD3 treatment group and the insulin group. Correlation analysis showed that 24-hour proteinuria was positively related with p38 MAPK, Col3, Col4 and immunohistochemical results; p38MAPK was positively correlated with Col3 and Col4 expressions. Conclusion Col3, Col4 and p38MAPK are up-regulated in rat models of type 2 diabetic nephropathy. The 1, 25-（ OH）2-VD3 might attenuates the progression of renal interstitial fibrosis via down-regulating p38 MAPK, Col3 and Col4.