Kitamoto Y, Tokunaga H, Miyamoto K, Tomita K
Department of Internal Medicine, Kumamoto University School of Medicine.
Rinsho Byori. 2000 Jun;48(6):485-90.
A glomerulus is a functional unit of the kidney, and endothelial cells in the glomerulus are often exposed to more than 5 times higher pressure than peripheral capillaries. Glomerular development proceeds through angiogenesis and VEGF was shown to mediate the angiogenesis. VEGF is constitutively expressed in the glomerulus from the embryo to adults. When VEGF signal was blocked by the antibody, glomerular endothelial cells were swollen and capillary lumen was interrupted. Changes were more prominent in the juxta-medullary than in the cortical glomerulus. A major VEGF receptor, Flk-1/KDR, is specifically localized to the glomerular endothelial cell among tissues and more predominantly in the juxta-medullary than in the cortical glomerulus. As capillary pressure is higher in the juxta-medullary than in the cortical glomeruli, endothelial cells in the former are exposed to more tension than those in the latter. VEGF might be a protective molecule for endothelial cells against tension. The effect of VEGF on the repair of an impaired glomerulus was evaluated in the rat Thy-1 glomerulonephritis. VEGF inhibited early endothelial injury and accelerated consequent remodeling of the glomerulus. In the patient study, VEGF excretion in the urine was independent from its serum or plasma level, but increased as renal function decreased. VEGF signaling is essential in glomerular development, maintenance and repair. VEGF excreted in the urine might reflect its generation in the kidney and be a unique marker of renal function.
肾小球是肾脏的功能单位，肾小球中的内皮细胞所承受的压力通常比外周毛细血管高出5倍以上。肾小球的发育通过血管生成进行，并且已表明血管内皮生长因子（VEGF）介导血管生成。从胚胎到成人，VEGF在肾小球中持续表达。当VEGF信号被抗体阻断时，肾小球内皮细胞肿胀，毛细血管腔中断。近髓肾小球的变化比皮质肾小球更明显。一种主要的VEGF受体，Flk-1/KDR，在各组织中特异性定位于肾小球内皮细胞，且在近髓肾小球中比在皮质肾小球中更显著。由于近髓肾小球中的毛细血管压力高于皮质肾小球，前者的内皮细胞比后者承受更大的张力。VEGF可能是内皮细胞抵抗张力的保护分子。在大鼠Thy-1肾小球肾炎中评估了VEGF对受损肾小球修复的作用。VEGF抑制早期内皮损伤并加速随后的肾小球重塑。在患者研究中，尿中VEGF排泄与其血清或血浆水平无关，但随肾功能下降而增加。VEGF信号传导在肾小球发育、维持和修复中至关重要。尿中排泄的VEGF可能反映其在肾脏中的生成情况，并且是肾功能的独特标志物。
