AngⅡ上调TRPC6、NFAT2介导2型糖尿病肾病足细胞损伤

ANGIOTENSIN Ⅱ MEDIATES PODOCYTE INJURY BY UPREGULATING TRANSIENT RECEPTOR POTENTIAL CATION CHANNEL 6 AND NUCLEAR FACTOR OF ACTIVATED T-CELLS 2 IN TYPE 2 DIABETIC NEPHROPATHY

目的 探讨瞬时受体电位阳离子通道蛋白6(TRPC6)、活化T细胞核因子2(NFAT2)参与血管紧张素Ⅱ(AngⅡ)介导的2型糖尿病肾病足细胞损伤的可能机制。方法 制备2型糖尿病大鼠模型,随机分为糖尿病组(DM组,n=11)、缬沙坦组(ARB组,n=11),同时设置正常对照组(NC组,n=10),ARB组给予缬沙坦40mg/(kg·d)灌胃,DM组及NC组给予等量生理盐水灌胃,干预12周后检测各组尿清蛋白排泄率(UAE),光镜、电镜下观察肾脏及足细胞病理改变,Western blot方法测定AngⅡ、NFAT2及TRPC6蛋白的表达水平。结果 DM组UAE显著高于NC组(F=261.834,t=22.80,P<0.01),ARB组UAE水平显著低于DM组(t=13.08,P<0.01)。光镜下可见,DM组较NC组肾小球体积增大、肾基底膜增厚、系膜细胞及系膜基质增生;电镜下可见,DM组足细胞数量减少,足突融合、消失,ARB组上述病变较DM组明显减轻。与NC组相比,DM组AngⅡ、NFAT2、TRPC6蛋白表达水平均显著升高(F=290.888~639.364,t=15.00~29.50,P<0.01),ARB组较DM组明显减低(t=22.81~34.01,P<0.01)。结论 AngⅡ可能通过上调TRPC6、NFAT2介导2型糖尿病足细胞损伤。

Objective To investigate the possible mechanism of transient receptor potential cation channel 6 (TRPC6) and nuclear factor of activated T-cells 2 (NFAT2) in podocyte injury mediated by angiotensin Ⅱ(AngⅡ) in type 2 diabetic nephropathy. Methods A rat model of type 2 diabetes was established, and then these rats were randomly divided into diabetes mellitus (DM) group with 11 rats and valsartan group (ARB group) with 11 rats. A total of 10 normal rats were enrolled as normal control group (NC group). The rats in the ARB group were given valsartan 40 mg/(kg·d) by gavage, and those in the DM group and the NC group were given an equal volume of normal saline by gavage. After 12 weeks of intervention, urinary albumin excretion (UAE) rate was measured;pathological changes of the kidney and podocytes were observed under a light microscope and an electron microscope;Western blot was used to measure the protein expression of AngⅡ, NFAT2, and TRPC6. Results The DM group had a significantly higher level of UAE than the NC group (F =261.834, t =22.80, P <0.01), and the ARB group had a significantly lower level of UAE than the DM group (t =13.08, P <0.01). Compared with the NC group under a light microscope, the DM group had significant increases in glomerular volume and glomerular basement membrane thickness, with marked proliferation of mesangial cells and mesangial matrix;compared with the NC group under an electron microscope, the DM group had a significant reduction in the number of podocytes, with foot process fusion and disappearance. The ARB group had significantly lower severities of the above pathological changes than the DM group. Compared with the NC group, the DM group had significant increases in the protein expression of AngⅡ, NFAT2, and TRPC6 (F =290.888-639.364, t =15.00-29.50, P <0.01), and the ARB group had significantly lower expression than the DM group (t =22.81-34.01, P <0.01). Conclusion AngⅡ may mediate podocyte injury in type 2 diabetes by upregulating TRPC6 and NFAT2.