保护素D1 通过抑制肾脏炎症及足突细胞上皮-间充质转化而抑制早期 糖尿病肾病小鼠肾纤维化

 目的：保护素D1 (PD1) 是一个潜在的抗炎症脂蛋白分子，本实验探讨其治疗早期糖尿病肾病（DN）肾纤维化的作用及机制。方法：用链脲佐菌素125 mg/kg 2次腹腔注射C57BL/6J雌性小鼠，建立早期DN小鼠模型。糖尿病模型成功后，用PD1（0.08 mg·kg-1·d-1）腹腔注射治疗，设正常鼠及DN鼠为对照。治疗8周后检测各组小鼠24 h尿蛋白及尿白蛋白定量、体重、肾重、肾重/体重比、血清及尿肌酐和肌酐清除率；用PAS染色法检测肾小球系膜区基质/肾小球面积比，用免疫荧光染色法检测肾皮质中巨噬细胞的数量，用Western blotting检测肾小球纤连蛋白（FN）和α-平滑肌肌动蛋白（α-SMA）的表达，以及肾小球足突细胞特异性上皮标志蛋白zonula occludens-1(ZO-1)和P-cadherin的表达；同时，体外用高糖刺激小鼠巨噬细胞株RAW264.7，检测PD1对其分泌肿瘤坏死因子α（TNF-α）和白细胞介素1β（IL-1β）的抑制作用。体外用转化生长因子β1（TGF-β1）刺激小鼠足突细胞株，用Western blotting检测PD1对其诱导足突细胞上皮-间充质转化(EMT)中上皮细胞标志蛋白P-cadherin 和ZO-1减少的恢复作用，及间充质细胞标志蛋白成纤维细胞特异性蛋白1（FSP1） 和α-SMA过表达的抑制作用。结果：PD1能减少DN小鼠肾小球系膜基质的积聚、24 h尿蛋白及尿白蛋白定量、体重、肾重和肾重/体重比，抑制异常增高的肌酐清除率。PD1能减少DN小鼠肾皮质中巨噬细胞的数量，抑制DN小鼠肾小球FN和α-SMA的表达，恢复足突细胞特异性上皮标志蛋白ZO-1和P-cadherin的表达。PD1能抑制高糖诱导RAW264.7分泌TNF-α和IL-1β，能抑制TGF-β1诱导足突细胞FSP1和α-SMA表达的增加以及ZO-1和P-cadherin表达的减少。结论：PD1能减轻早期DN小鼠肾纤维化，其部分机制可能通过抑制肾脏的炎症及足突细胞EMT。

Protectin D1 inhibits renal fibrosis in early-stage diabetic nephropathy mice by inhibiting renal inflammation and podocyte epithelial-mesenchymal transition

AIM:To study the effect of protectin D1 (PD1) as a potent anti-inflammatory lipid mediator on diabetic nephropathy (DN). METHODS:PD1 (0.08 mg·kg-1·d-1) was intraperitoneally injected into the mice for 8 weeks after diabetes was induced by injection of streptozotocin. The 24-h urinary protein and albumin levels, body weight, renal weight, kidney-to-body weight ratio, creatinine clearance, glomerular mesangial matrix accumulation, renal cortical macrophage accumulation,  and glomerular expression of fibronectin (FN), α-smooth muscle actin (α-SMA), zonula occludens-1 (ZO-1) and P-cadherin were detected. Thfe effect of PD1 on inhibiting epithelial-mesenchymal transition (EMT) in the podocytes induced by transforming growth factor β1 (TGF-β1), and the effect of PD1 on inhibiting the inflammatory effect of macrophages induced by high glucose were determined. RESULTS:PD1 markedly suppressed diabetes-induced elevation of 24-h urinary protein and albumin levels, body weight, renal weight, kidney-to-body weight ratio, creatinine clearance, glomerular mesangial matrix accumulation, and glomerular expression of FN and α-SMA. PD1 also suppressed diabetes-induced increase in the number of renal cortical macrophages in the mice with DN. Analysis by Western blotting and immunohistochemistry revealed that PD1 suppressed diabetes-induced elevation of mesenchymal/fibrotic markers FN and α-SMA, and increased podocyte-related epithelial markers ZO-1 and P-cadherin in the glomeruli of the mice with DN. PD1 repressed high glucose-induced generation of tumor necrosis factor α and interleukin 1β by macrophages, and inhibited TGF-β1-induced increases in fibroblast-specific protein 1 and α-SMA, and inhibited TGF-β1-induced decreases in epithelial markers P-cadherin and ZO-1 in podocytes in vitro. CONCLUSION: PD1 inhibits renal fibrosis in the early stage of DN, and its mechanisms may be related to its anti-inflammatory and anti-EMT effects on podocytes.