促红细胞生成素及其受体在慢性环孢素A肾毒性大鼠肾组织中的表达

目的探讨慢性环孢素A(CsA)能否导致贫血,以及促红细胞生成素(EPO)及其受体(EPOR)在慢性CsA肾毒性大鼠肾组织中的表达变化。方法 SD大鼠给予CsA15mg/(kg·d)皮下注射4周建立慢性CsA肾毒性模型(CsA毒性组),对照组1mL/(kg·d)皮下注射橄榄油。采用全自动生化分析仪检测两组大鼠的肾功能,血红蛋白(Hb)、红细胞压积(Hct)水平,三色(Masson Trichrome)染色确定肾小管间质纤维化程度;免疫组织化学染色和蛋白质印迹法分别检测肾组织EPO及EPOR蛋白的表达;TUNEL染色和电子显微镜观察细胞凋亡。结果与对照组相比,CsA毒性组大鼠肾功能低下,肾小管间质发生纤维化,凋亡细胞增多(P<0.01);同时CsA毒性组大鼠有贫血发生,表现为Hb和Hct水平的下降(P<0.01)。免疫组织化学染色和蛋白质印迹分析结果表明,EPO在CsA毒性组肾组织中的表达减少,而EPOR的表达增加(P<0.01)。直线相关分析提示,EPO蛋白表达与肾小管间质纤维化(r=-0.729,P<0.001)和TUNEL阳性细胞数(r=-0.841,P<0.001)呈负相关。结论慢性CsA肾毒性大鼠肾组织中EPO蛋白表达减少,从而导致贫血;CsA诱导肾小管上皮细胞凋亡与EPO蛋白表达减少有关。

Expression of erythropoietin and its receptor in renal tissues of rats with chronic cyclosporine A nephrotoxicity

Objective: To examine: 1) whether cyclosporine A (CsA) treatment induces anemia; 2) the expression of erythropoietin (EPO) and its receptor (EPOR) in chronic cyclosporine A nephrotoxicity in the rats. Methods: Sprague-Dawley rats kept on a low salt diet (0.05% sodium) were treated daily for 4 weeks with subcutaneous injections of vehicle (olive oil, 1mL/kg) or CsA (15mg/kg). Body weight, renal function, and hematopoietic parameters were determined. In addition, renal histopathology (tubulointerstitial fibrosis), apoptotic cell death (TUNEL assay), and expressions of erythropoietin (EPO) and its receptor (EPOR) were also investigated. Results: Compared with the normal rats, rats given CsA showed loss of body weight, renal insufficiency, and anemia, with the development of striped tubulointerstitial fibrosis and apoptotic cell death. Immunohistochemistry and immunoblotting revealed that CsA treatment significantly decreased EPO expression compared with the vehicle group, whereas EPOR expression was enhanced. Furthermore, EPO protein expression was negatively associated with the number of TUNEL-positive cells and the percentage of tubulointerstitial fibrosis. Conclusion: Long-term treatment with CsA decreases intrarenal EPO expression resulting in anemia, and that this is closely related to tubular epithelial cell apoptosis.