The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai Key Laboratory of Compound Chinese Medicines and The SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai Key Laboratory of Compound Chinese Medicines and The SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
Biochem Pharmacol. 2019 Jan;159:82-95. doi: 10.1016/j.bcp.2018.11.011. Epub 2018 Nov 14.
The breakdown of blood-retinal barrier (BRB) is an early and typical event during the development of diabetic retinopathy (DR). Scutellarin (SC) is a natural flavonoid. This study aims to investigate the protection of SC from BRB damage via focusing on inhibiting microglia-initiated inflammation and subsequent oxidative stress injury. SC attenuated BRB breakdown and the reduced expression of claudin-1 and claudin-19 in STZ-induced diabetic mice. SC reduced microglia cells activation both in vivo and in vitro. The results of transendothelial/transepithelial electrical resistance (TEER/TER) and fluorescein isothiocyanate (FITC)-conjugated dextran cell permeability assay showed that SC attenuated BRB damage induced by d-glucose (25 mM)-stimulated microglia BV2 cells. SC suppressed nuclear factor κB (NFκB) activation and tumor necrosis factor (TNF)-α expression induced by d-glucose (25 mM) in BV2 cells. SC decreased the phosphorylation of extracellular regulated protein kinase (ERK)1/2 both in vivo and in vitro. MEK1/2 inhibitor U0126 reduced the d-glucose-induced NFκB nuclear accumulation and TNFα expression in BV2 cells. Next, SC improved the decreased expression of claudin-1 and claudin-19, the increased BRB damage and cellular reactive oxygen species (ROS) formation, and enhanced nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) in TNFα-treated human retinal endothelial cells (HRECs) and APRE19 cells. Moreover, the SC-provided alleviation on BRB breakdown in STZ-induced diabetic mice was diminished in Nrf2 knock-out mice. In conclusion, SC alleviates BRB breakdown via abrogating retinal inflammatory responses and subsequent oxidative stress injury initiated by microglia cells that is activated by hyperglycemia during DR development.
血视网膜屏障（BRB）的破坏是糖尿病性视网膜病变（DR）发展过程中的早期和典型事件。野黄芩苷（SC）是一种天然黄酮类化合物。本研究旨在通过抑制小胶质细胞引发的炎症和随后的氧化应激损伤来研究 SC 对 BRB 损伤的保护作用。SC 可减轻 STZ 诱导的糖尿病小鼠 BRB 破裂，并降低紧密连接蛋白-1 和紧密连接蛋白-19 的表达。SC 减少了小胶质细胞在体内和体外的激活。跨内皮/跨上皮电阻（TEER/TER）和荧光素异硫氰酸酯（FITC）结合的葡聚糖细胞通透性测定的结果表明，SC 可减轻 d-葡萄糖（25 mM）刺激的小胶质细胞 BV2 细胞引起的 BRB 损伤。SC 抑制了 d-葡萄糖（25 mM）诱导的 BV2 细胞中核因子 κB（NFκB）的激活和肿瘤坏死因子（TNF）-α的表达。SC 降低了体内和体外 ERK1/2 的磷酸化。MEK1/2 抑制剂 U0126 减少了 d-葡萄糖诱导的 BV2 细胞中 NFκB 的核积累和 TNFα的表达。接下来，SC 改善了 TNFα处理的人视网膜内皮细胞（HRECs）和 APRE19 细胞中紧密连接蛋白-1 和紧密连接蛋白-19 的表达降低，BRB 损伤增加，细胞活性氧（ROS）形成增加，核因子红细胞 2 相关因子 2（Nrf2）的核积累增加。此外，在 Nrf2 敲除小鼠中，SC 减轻了 STZ 诱导的糖尿病小鼠中 BRB 破裂的作用减弱。总之，SC 通过阻断高血糖诱导的小胶质细胞激活引起的视网膜炎症反应和随后的氧化应激损伤来减轻 BRB 破裂，从而在 DR 发展过程中发挥作用。
