Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Department of Human Resource Development of Dialysis Therapy for Kidney Disease, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
PLoS One. 2018 Apr 11;13(4):e0195779. doi: 10.1371/journal.pone.0195779. eCollection 2018.
Angiogenesis has been implicated in glomerular alterations in the early stage of diabetic nephropathy. We previously reported the renoprotective effects of vasohibin-1 (VASH1), which is a novel angiogenesis inhibitor derived from endothelial cells, on diabetic nephropathy progression. Vasohibin-2 (VASH2) was originally identified as a VASH1 homolog and possesses pro-angiogenic activity in contrast to VASH1. In addition, VASH2 was recently shown to promote epithelial-to-mesenchymal transition via enhanced transforming growth factor (TGF)-β signaling in cancer cells. Herein, we investigated the pathogenic roles of VASH2 in diabetic nephropathy using VAHS2-deficient mice. The type 1 diabetes model was induced by intraperitoneal injections of streptozotocin in VASH2 homozygous knockout (VASH2LacZ/LacZ) or wild-type mice. These mice were euthanized 16 weeks after inducing hyperglycemia. Increased urine albumin excretion and creatinine clearance observed in diabetic wild-type mice were significantly prevented in diabetic VASH2-deficient mice. Accordingly, diabetes-induced increase in glomerular volume and reduction in glomerular slit-diaphragm density were significantly improved in VASH2 knockout mice. Increased glomerular endothelial area was also suppressed in VASH2-deficient mice, in association with inhibition of enhanced vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2), but not VEGF level. Furthermore, glomerular accumulation of mesangial matrix, including type IV collagen, and increased expression of TGF-β were improved in diabetic VASH2 knockout mice compared with diabetic wild-type mice. Based on the immunofluorescence findings, endogenous VASH2 localization in glomeruli was consistent with mesangial cells. Human mesangial cells (HMCs) were cultured under high glucose condition in in vitro experiments. Transfection of VASH2 small interfering RNA (siRNA) into the HMCs resulted in the suppression of type IV collagen production induced by high glucose compared with control siRNA. These results indicate that VASH2 may be involved in diabetes-induced glomerular alterations, particularly impaired filtration barrier and mesangial expansion. Therefore, VASH2 is likely to represent a promising therapeutic target for diabetic nephropathy.
血管生成在糖尿病肾病早期的肾小球改变中起作用。我们之前报道了血管抑素-1（VASH1）对糖尿病肾病进展的肾保护作用，VASH1 是一种源自内皮细胞的新型血管生成抑制剂。血管抑素-2（VASH2）最初被鉴定为 VASH1 的同源物，与 VASH1 相反，具有促血管生成活性。此外，最近的研究表明，VASH2 通过增强转化生长因子（TGF）-β信号在癌细胞中促进上皮-间充质转化。在此，我们使用 VASH2 缺陷小鼠研究了 VASH2 在糖尿病肾病中的致病作用。1 型糖尿病模型是通过腹腔注射链脲佐菌素在 VASH2 纯合敲除（VASH2LacZ/LacZ）或野生型小鼠中诱导的。这些小鼠在诱导高血糖后 16 周被安乐死。在糖尿病野生型小鼠中观察到的尿白蛋白排泄增加和肌酐清除率显著降低在糖尿病 VASH2 缺陷型小鼠中得到预防。因此，VASH2 敲除小鼠的肾小球体积增加和肾小球裂孔隔膜密度降低得到显著改善。VASH2 缺陷小鼠中也抑制了肾小球内皮面积增加，同时抑制了增强的血管内皮生长因子（VEGF）受体 2（VEGFR2），但不抑制 VEGF 水平。此外，与糖尿病野生型小鼠相比，糖尿病 VASH2 敲除小鼠的肾小球系膜基质积累，包括 IV 型胶原，和 TGF-β的表达增加得到改善。根据免疫荧光研究结果，肾小球中内源性 VASH2 的定位与系膜细胞一致。在体外实验中，将 VASH2 小干扰 RNA（siRNA）转染入人肾小球系膜细胞（HMC）中，与对照 siRNA 相比，高葡萄糖诱导的 IV 型胶原产生受到抑制。这些结果表明，VASH2 可能参与了糖尿病引起的肾小球改变，特别是滤过屏障受损和系膜扩张。因此，VASH2 可能是糖尿病肾病的一个有希望的治疗靶点。
