Liu Li, Jiang Youde, Steinle Jena J
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA.
J Vasc Res. 2017;54(6):367-375. doi: 10.1159/000480455. Epub 2017 Nov 15.
We reported that β-adrenergic receptors regulate toll-like receptor 4 (TLR4) signaling in the retina of diabetic mice and in retinal endothelial cells (REC) and Müller cells. We hypothesized that TLR4 regulates retinal permeability both in vitro and in vivo in the retinal vasculature. We used REC cultured in normal and high-glucose conditions and TLR4 siRNA treatments for cell culture studies of permeability and protein analyses of tumor necrosis factor α, occludin, and zonula occludens 1 (ZO-1). We used endothelial cell (EC)-specific Cre-Lox TLR4 knockout mice to study retinal permeability and neuronal and vascular changes following exposure to ocular ischemia/reperfusion (I/R) used as a retinal stressor. We found that the loss of TLR4 in the EC led to the reduced permeability following I/R and fewer degenerate capillaries. Retinal permeability was increased in REC grown in high-glucose conditions but was inhibited by TLR4 siRNA treatment. High-glucose culture conditions significantly reduced occludin and ZO-1 levels in REC, and TLR4 siRNA treatment restored levels to baseline. In conclusion, these studies demonstrate that TLR4 in EC strongly regulates retinal permeability and neuronal and vascular changes following exposure to stressors such as I/R.
我们报道了β-肾上腺素能受体在糖尿病小鼠视网膜以及视网膜内皮细胞（REC）和 Müller 细胞中调节 Toll 样受体 4（TLR4）信号通路。我们推测 TLR4 在体外和体内均调节视网膜血管系统的视网膜通透性。我们使用在正常和高糖条件下培养的 REC 以及 TLR4 siRNA 处理进行细胞培养，以研究通透性，并对肿瘤坏死因子α、闭合蛋白和紧密连接蛋白 1（ZO-1）进行蛋白质分析。我们使用内皮细胞（EC）特异性 Cre-Lox TLR4 基因敲除小鼠来研究暴露于眼部缺血/再灌注（I/R）（作为视网膜应激源）后视网膜的通透性以及神经元和血管变化。我们发现 EC 中 TLR4 的缺失导致 I/R 后通透性降低以及退化的毛细血管减少。在高糖条件下培养的 REC 中视网膜通透性增加，但 TLR4 siRNA 处理可抑制这种增加。高糖培养条件显著降低了 REC 中闭合蛋白和 ZO-1 的水平，而 TLR4 siRNA 处理可将水平恢复至基线。总之，这些研究表明 EC 中的 TLR4 在暴露于诸如 I/R 等应激源后强烈调节视网膜通透性以及神经元和血管变化。
