쥐혈관사이세포에서 시클로스포린에 의한 섬유결합소 합성에 있어 Simvastatin의 억제효과

Abstract

Background: Cyclosporin A (CsA) is not only an effective immunosuppressant for prevention of rejection after kidney transplantation, but also a treatment agent for autoimmune diseases and primary kidney diseases. However, CsA has nephrotoxicity that can lead to chronic allograft nephropathy and renal fibrosis. It is known that simvastatin attenuates established hypercholesterolemia after renal transplantation and preserves structures and functions of glomeruli. However, it is not well known how simvastatin acts on CsA-induced fibronectin synthesis. Therefore, we investigated the effect of simvastatin on Smad pathway, which is the key pathway of CsA induced fibronectin synthesis in rat mesangial cells. Methods: Transforming growth factor-β1 (TGF-β1) was induced by cyclosporine in cultured rat mesangial cells (RMCs). Optimal concentration and exposure time of the CsA were selected according to its concentration (0.1 ~ 10 μM) and TGF-β1 expression time (1~72 h) by enzyme-linked immunoabsorbent assay. All RMCs were divided into six experimental groups: control, CsA 1 μM alone, simvastatin 1 μM alone, simvastatin 0.1 μM pretreatment CsA 1 μM, simvastatin 1 μM pretreatment CsA 1 μM, and simvastatin 10 μM pretreatment CsA 1 μM. The level of TGF-β1, phosphorylated Smad3 (phospho-Smad3), Smad7 and fibronectin proteins were measured by semiquantitative immunoblotting. Results: TGF-β1 production was significantly increased at 1 μM CsA, and was maximal 24h after CsA treatment. After treatment with CsA alone, the level of TGF-β1 expression significantly increased (4.00 ± 1.27-fold, p=0.0035). Phospho-Smad3 and fibronectin production also significantly increased after CsA 1 μM treatment (2.90 ± 0.05-fold, p=0.006, 1.81 ± 0.22-fold, p=0.0085). When all the simvastatin pretreatment CsA 1 μM groups were compared with those treated with CsA alone, TGF-β1 (p<0.05), phospho-Smad3 expression (p<0.05) and fibronectin production (p<0.05) significantly decreased. However, in simvastatin 10 μM pretreatment CsA 1 μM group, the level of Smad7 expression was significantly increased compared with control (p=0.0316). Conclusion: This study demonstrates that simvastatin may ameliorate CsA-induced fibronectin synthesis by modulating the TGF-β1/Smad pathway in RMCs. These results suggest that simvastatin may inhibit the development of glomerulosclerosis and subsequent, CsA nephropathy.