Wu M-J, Chang C-H, Shu K-H, Ho H-C, Li J-R, Fu Y-C
Division of Nephrology, Taichung Veterans General Hospital, Taiwan; School of Medicine, Chung Shan Medical University, Taiwan; Graduate Institute of Clinical Medical Science, School of Medicine, China Medical University, Taiwan; Institute of Biomedical Science, National Chung Hsing University, Taiwan; Department of Life Science, Tunghai University, Taiwan.
Institute of Clinical Medicine, School of Medicine, National Yang Ming University, Taiwan.
Transplant Proc. 2014 May;46(4):1226-8. doi: 10.1016/j.transproceed.2013.12.011.
Conversion to rapamycin from calcineurin inhibitors may contribute to improvement of graft function in kidney transplant recipients, especially in patients with calcineurin inhibitor-related nephrotoxicity. The conversion from calcineurin inhibitors to rapamycin in kidney transplant recipients has been associated with a higher incidence of proteinuria. It could be explained by possible hemodynamic changes due to withdrawal of calcineurin inhibitors. Podocyte damage occurs commonly in rapamycin-related proteinuria. The vascular endothelial growth factor system has been suggested to be implicated in mammalian target of rapamycin inhibitor-associated proteinuria. However, induction of urokinase receptor (uPAR) signaling in podocytes leads to foot process effacement and urinary protein. In this study, we assessed the role of uPAR in primary cultured podocytes with rapamycin treatment. Our results indicate that 24-hour rapamycin treatment promotes podocyte migration on the wound scratch assay in a dose-dependent manner. Rapamycin treatment for 2 days does not increase the apoptosis of podocytes or affect the podocyte cell viability and morphology. The up-regulation of uPAR in podocytes was confirmed by immunofluorescence staining, real-time polymerase chain reaction (1.8 ± 0.3-fold increase of relative quantification; P < .01) and Western blot analysis. Rapamycin treatment also causes the activation of FAK and ILK in a dose-dependent manner. In summary, rapamycin could promote podocyte migration through the up-regulation of uPAR. This finding provides a new mechanism of rapamycin-associated proteinuria. It also suggests that pharmacologic inhibition of uPAR signaling cascade may have therapeutic potential in the setting of rapamycin-related proteinuria.
从钙调神经磷酸酶抑制剂转换为雷帕霉素可能有助于改善肾移植受者的移植肾功能，尤其是在患有钙调神经磷酸酶抑制剂相关肾毒性的患者中。肾移植受者从钙调神经磷酸酶抑制剂转换为雷帕霉素与蛋白尿发生率较高有关。这可能是由于停用钙调神经磷酸酶抑制剂导致的血流动力学变化所致。足细胞损伤在雷帕霉素相关蛋白尿中很常见。血管内皮生长因子系统被认为与雷帕霉素抑制剂相关蛋白尿有关。然而，足细胞中尿激酶受体（uPAR）信号的诱导会导致足突消失和尿蛋白。在本研究中，我们评估了uPAR在雷帕霉素处理的原代培养足细胞中的作用。我们的结果表明，24小时雷帕霉素处理以剂量依赖的方式促进了伤口划痕试验中的足细胞迁移。雷帕霉素处理2天不会增加足细胞的凋亡，也不会影响足细胞的细胞活力和形态。通过免疫荧光染色、实时聚合酶链反应（相对定量增加1.8±0.3倍；P <.01）和蛋白质印迹分析证实了足细胞中uPAR的上调。雷帕霉素处理还以剂量依赖的方式导致FAK和ILK的激活。总之，雷帕霉素可通过上调uPAR促进足细胞迁移。这一发现为雷帕霉素相关蛋白尿提供了一种新机制。它还表明，uPAR信号级联的药物抑制在雷帕霉素相关蛋白尿的情况下可能具有治疗潜力。
