Supplementary Material for: Renoprotection by Continuous Erythropoietin Receptor Activator in Puromycin Aminonucleoside-Induced Nephrotic Syndrome

Background/Aims: Recent studies have demonstrated that erythropoiesis-stimulating agents (ESAs) induce a tissue-protective effect in the kidney. In this study, we examined whether continuous erythropoietin receptor activator (CERA), a long-acting ESA, could prevent kidney injury, especially podocyte damage, in a rat model of nephrotic syndrome induced by puromycin aminonucleoside (PAN). Methods: Rats were injected with CERA (30 µg/kg) or vehicle 4 h before the injection of PAN (50 mg/kg). Renal function, kidney injury, and podocyte damage were assessed at 7 days. Results: The levels of proteinuria, BUN, and plasma creatinine significantly increased in rats with PAN-induced nephrosis. Treatment with CERA significantly prevented these deteriorations induced by PAN. Glomerular lesions, especially vacuolation of podocytes, and the increase of desmin expression in PAN-treated rats were significantly ameliorated by treatment with CERA. Treatment with CERA also significantly prevented the decrease in the protein productions of nephrin and podocin in the kidneys of PAN-treated rats. We found persistent activation of the Akt signaling pathway in the kidneys of CERA-treated rats. Conclusion: CERA could ameliorate renal dysfunction in PAN-induced nephrosis, which might be due to the amelioration of podocyte injury. CERA inhibited the depletion of nephrin and podocin, key components of the glomerular filtration barrier, and alleviated proteinuria. Activation of the Akt signaling pathway might be involved in the renoprotective effect of CERA

背景与目的：近期研究证实，促红细胞生成素类药物（erythropoiesis-stimulating agents, ESAs）可对肾脏发挥组织保护作用。本研究旨在探讨长效促红细胞生成素受体激活剂（continuous erythropoietin receptor activator, CERA，一种长效ESAs）是否可在嘌呤霉素氨基核苷（puromycin aminonucleoside, PAN）诱导的肾病综合征大鼠模型中，预防肾损伤尤其是足细胞损伤。
方法：大鼠于注射嘌呤霉素氨基核苷（50 mg/kg）前4小时，分别给予CERA（30 μg/kg）或溶剂对照。于造模后7天评估肾功能、肾损伤及足细胞损伤状况。
结果：嘌呤霉素氨基核苷诱导肾病的大鼠，其尿蛋白、血尿素氮（blood urea nitrogen, BUN）及血浆肌酐水平均显著升高；CERA治疗可显著改善上述由嘌呤霉素氨基核苷诱导的病情恶化。嘌呤霉素氨基核苷处理大鼠的肾小球病变（尤以足细胞空泡变性为著）及结蛋白（desmin）表达上调均被CERA治疗显著缓解。此外，CERA治疗还可显著阻止嘌呤霉素氨基核苷处理大鼠肾脏中肾病蛋白（nephrin）及足细胞蛋白podocin（podocin）的蛋白表达水平降低。本研究发现，CERA治疗大鼠的肾脏中Akt信号通路呈持续激活状态。
结论：CERA可改善嘌呤霉素氨基核苷诱导的肾病大鼠肾功能不全，其机制可能与缓解足细胞损伤有关。CERA可抑制肾小球滤过屏障关键组分肾病蛋白及足细胞蛋白的耗竭，并减轻蛋白尿。Akt信号通路的激活可能参与了CERA的肾脏保护作用。