Tarabra Elena, Giunti Sara, Barutta Federica, Salvidio Gennaro, Burt Davina, Deferrari Giacomo, Gambino Roberto, Vergola Daniela, Pinach Silvia, Perin Paolo Cavallo, Camussi Giovanni, Gruden Gabriella
Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy.
Diabetes. 2009 Sep;58(9):2109-18. doi: 10.2337/db08-0895. Epub 2009 Jul 8.
Monocyte chemoattractant protein-1 (MCP-1), a chemokine binding to the CC chemokine receptor 2 (CCR2) and promoting monocyte infiltration, has been implicated in the pathogenesis of diabetic nephropathy. To assess the potential relevance of the MCP-1/CCR2 system in the pathogenesis of diabetic proteinuria, we studied in vitro if MCP-1 binding to the CCR2 receptor modulates nephrin expression in cultured podocytes. Moreover, we investigated in vivo if glomerular CCR2 expression is altered in kidney biopsies from patients with diabetic nephropathy and whether lack of MCP-1 affects proteinuria and expression of nephrin in experimental diabetes.
Expression of nephrin was assessed in human podocytes exposed to rh-MCP-1 by immunofluorescence and real-time PCR. Glomerular CCR2 expression was studied in 10 kidney sections from patients with overt nephropathy and eight control subjects by immunohistochemistry. Both wild-type and MCP-1 knockout mice were made diabetic with streptozotocin. Ten weeks after the onset of diabetes, albuminuria and expression of nephrin, synaptopodin, and zonula occludens-1 were examined by immunofluorescence and immunoblotting.
In human podocytes, MCP-1 binding to the CCR2 receptor induced a significant reduction in nephrin both mRNA and protein expression via a Rho-dependent mechanism. The MCP-1 receptor, CCR2, was overexpressed in the glomerular podocytes of patients with overt nephropathy. In experimental diabetes, MCP-1 was overexpressed within the glomeruli and the absence of MCP-1 reduced both albuminuria and downregulation of nephrin and synaptopodin.
These findings suggest that the MCP-1/CCR2 system may be relevant in the pathogenesis of proteinuria in diabetes.
单核细胞趋化蛋白-1（MCP-1）是一种与CC趋化因子受体2（CCR2）结合并促进单核细胞浸润的趋化因子，已被证实与糖尿病肾病的发病机制有关。为了评估MCP-1/CCR2系统在糖尿病蛋白尿发病机制中的潜在相关性，我们在体外研究了MCP-1与CCR2受体的结合是否会调节培养的足细胞中nephrin的表达。此外，我们在体内研究了糖尿病肾病患者肾活检中肾小球CCR2的表达是否改变，以及缺乏MCP-1是否会影响实验性糖尿病中的蛋白尿和nephrin的表达。
通过免疫荧光和实时PCR评估暴露于重组人MCP-1（rh-MCP-1）的人足细胞中nephrin的表达。通过免疫组织化学研究了10例显性肾病患者和8例对照受试者的肾切片中肾小球CCR2的表达。野生型和MCP-1基因敲除小鼠均用链脲佐菌素诱导糖尿病。糖尿病发病10周后，通过免疫荧光和免疫印迹检测蛋白尿以及nephrin、突触足蛋白和闭合蛋白-1的表达。
在人足细胞中，MCP-1与CCR2受体的结合通过Rho依赖机制导致nephrin的mRNA和蛋白表达显著降低。在显性肾病患者的肾小球足细胞中，MCP-1受体CCR2过表达。在实验性糖尿病中，肾小球内MCP-1过表达，而缺乏MCP-1可减少蛋白尿以及nephrin和突触足蛋白的下调。
这些发现表明，MCP-1/CCR2系统可能与糖尿病蛋白尿的发病机制有关。
