Vascular permeability in experimental diabetes is associated with reduced endothelial occludin content - Vascular endothelial growth factor decreases occludin in retinal endothelial cells
Vascular permeability in experimental diabetes is associated with reduced endothelial occludin content - Vascular endothelial growth factor decreases occludin in retinal endothelial cells
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DOI：
10.2337/diabetes.47.12.1953
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发表时间：
1998-12-01
期刊：
影响因子：
7.7
通讯作者：
Gardner, TW
中科院分区：
文献类型：
--
作者：
Antonetti, DA;Barber, AJ;Gardner, TW
血视网膜屏障（BRB）的破坏是糖尿病视网膜病变的标志，但导致这种病理的分子变化尚不清楚。封闭蛋白是内皮细胞间紧密连接的跨膜成分，可调节BRB的通透性。在这项研究中，我们研究了血管内皮生长因子（VEGF）和糖尿病对血管occludin含量和屏障功能的影响。通过静脉注射链脲佐菌素使Sprague-Dawley大鼠患糖尿病，年龄匹配的动物作为对照。3个月后，通过静脉注射异硫氰酸荧光素-牛血清白蛋白（FITC-BSA）、M-r 66 kDa和10-kDa罗丹明-葡聚糖（R-D），然后对视网膜切片进行数字图像分析，对BRB渗透性进行定量。FITC-BSA的视网膜荧光强度增加62%（P小于或等于0.05），但R-D荧光没有显著改变，通过免疫荧光证实了内皮间连接处的封闭蛋白定位，并通过视网膜匀浆的免疫印迹测定了相对蛋白含量，与对照组相比，糖尿病组大鼠视网膜中occludin含量降低了约35%（P小于或等于0.03），而大鼠视网膜中葡萄糖转运蛋白GLUT 1含量没有变化。此外，治疗牛视网膜内皮细胞培养与0.12 nmol/L或12 nmol/L的VEGF 6小时减少occludin含量分别为46%和54%。这些数据表明，糖尿病选择性降低视网膜occludin蛋白表达，并增加BRB渗透性。我们的研究结果表明，糖尿病视网膜病变患者玻璃体中VEGF的升高通过下调occludin的含量增加血管通透性。紧密连接蛋白表达减少可能是糖尿病导致血管通透性增加并导致黄斑水肿的重要手段。
Blood-retinal barrier (BRB) breakdown is a hallmark of diabetic retinopathy, but the molecular changes that cause this pathology are unclear. Occludin is a transmembrane component of interendothelial tight junctions that may regulate permeability at the BRB. In this study, we examined the effects of vascular endothelial growth factor (VEGF) and diabetes on vascular occludin content and barrier function. Sprague-Dawley rats were made diabetic by intravenous streptozotocin injection, and age-matched animals served as controls. After 3 months, BRB permeability was quantified by intravenous injection of fluorescein isothiocyanate-bovine serum albumin (FITC-BSA), M-r 66 kDa, and 10-kDa rhodamine-dextran (R-D), followed by digital image analysis of retinal sections. Retinal fluorescence intensity for FITC-BSA increased 62% (P less than or equal to 0.05), but R-D fluorescence did not change significantly Occludin localization at interendothelial junctions was confirmed by immunofluorescence, and relative protein content was determined by immunoblotting of retinal homogenates, Retinal occludin content decreased -35% (P less than or equal to 0.03) in the diabetic versus the control animals, whereas the glucose transporter GLUT1 content was unchanged in rat retinas. Additionally, treatment of bovine retinal endothelial cells in culture with 0.12 nmol/l or 12 nmol/l VEGF for 6 h reduced occludin content 46 and 54%, respectively. These data show that diabetes selectively reduces retinal occludin protein expression and increases BRB permeability. Our findings suggest that the elevated VEGF in the vitreous of patients with diabetic retinopathy increases vascular permeability by downregulating occludin content. Decreased tight junction protein expression may be an important means by which diabetes causes increased vascular permeability and contributes to macular edema.