地塞米松对阿霉素诱导的肾小球足细胞活动力的影响

目的探讨地塞米松（dexamethasone,Dex）改善阿霉素(adriamycin,ADR)诱导的肾小球足细胞活性的机制。方法将体外培养的小鼠肾小球足细胞分为3组:ADR组，Dex预处理组（Dex+ADR）和空白对照组。采用划痕实验、Transwell实验、异硫氰酸荧光素标记的牛血清白蛋白（FITC-BSA）方法进行肾小球足细胞功能分析。另取SD雄性大鼠72只，随机分为ADR组（尾静脉注射ADR 7.5 mg/kg），Dex治疗组（ADR+Dex，尾静脉注射ADR 7.5 mg/kg后24 h，再注射Dex 1 mg/kg）和对照组（尾静脉注射等量生理盐水），分别给药后7 d、14 d、21 d和28 d收集24 h尿液，测定24 h尿蛋白。采用实时荧光定量PCR和Western blot分别检测nephrin表达变化。电镜下平均足突宽度（FWP）进行相关分析。结果划痕实验和Transwell结果显示，与空白对照组相比，ADR诱导肾小球足细胞活性升高，而Dex预处理后，肾小球足细胞的活力明显下降，与ADR组的差异有统计学意义（P<0.05）。FITC-BSA结果显示，与空白对照组相比，ADR诱导肾病肾小球足细胞FITC-BSA滤过率升高（P<0.05）；与ADR组相比，Dex预处理组肾小球足细胞FITC-BSA滤过率降低（P<0.05）。实时荧光定量PCR和Western Blot结果显示，与对照组大鼠比较，ADR诱导的肾病组肾小球足细胞nephrin表达升高（P<0.05），而Dex预处理后，大鼠肾小球足细胞nephrin 表达下调（P<0.05）。电镜下结果显示，ADR组大鼠FWP高于正常组（P<0.01）；与ADR组相比，Dex治疗组FWP降低（P<0.01）。与对照组相比，ADR注射14 d开始，大鼠24 h尿蛋白增多（P<0.01），第28天达到峰值（P<0.001）。与ADR组相比，Dex治疗组大鼠第14、21和28天24 h尿蛋白下降（P<0.001）。结论Dex下调nephrin表达，进而拮抗ADR诱导的体外肾小球足细胞活动力升高，参与缓解肾病大鼠的蛋白尿发生。

Dexamethasone Blocks Adriamycin-induced Podocytes'Mobility via Impacting Nephrin Expression

ObjectiveTo explore how dexamethasone (Dex) directly restores kidney podocyte function in adriamycin (ADR)-induced nephrotic model and the effects of Dex on the motility of podocytes,to analyze whether nephrin is a key signal molecule in the process. MethodsThe cultured podocytes were divided into three growps: ADR treated group,ADR+Dex group,blank control group. The analyses of podocytes function were performed using scrape-wound,Transwell migration assays and FITC-BSA. Quantitative real-time PCR and Western blot were used to test the expression of nephrin. Male SD rats were used to generate ADR-induced nephrology model,and randomly divided into three groups: ADR group,ADR+Dex group and normal group. At 7 d,14 d,21 d and 28 d after ADR injection,24 h urine protein was measured as well. Podocyte foot process effacement was observed under transmission electron microscopy. ResultsPodocytes’ motility,permeability of a monolayer of podocytes incubated with FITC-BSA,the expression of nephrin were higher in ADR group than those in blank control group (P<0.05); on the contrary,the indexes above in Dex+ADR group were decreased when compared with ADR group (P<0.05). 24 h urine protein increased significantly at day 14 (vs. normal group P<0.001) and peaked at day 28 in ADR rats (vs. normal group P<0.001),whereas decreased at day 14,21 and 28 in Dex+ADR group (vs. ADR group,P<0.001). The FWP of ADR-treated rats was greater than normal group and Dex+ADR group (P<0.01). ConclusionDex impacts the expression of nephrin,relieves the enhanced motility induced by ADR and decreases urine protein level.