Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand.
Int J Toxicol. 2010 Jul;29(4):418-24. doi: 10.1177/1091581810366487. Epub 2010 May 5.
Tight junction is a crucial structure in the control of paracellular transport across epithelial/endothelial barriers. This study investigated the protective effect of quercetin against hydrogen peroxide (H(2)O(2))-induced tight junction disruption and hyperpermeability in ECV304 monolayers. Nonlethal concentration of H(2)O(2) (100 micromol/L; 4 hours) decreased expression of the tight junction proteins zonular occudens (ZO)-1 and occludin as well as disrupted the junction structure at the cell border. Concurrently, the increased activities of extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) were observed. Pretreatment with quercetin (10 micromol/L; 30 minutes) prior to H(2)O(2) prevented the loss of ZO-1 and occludin. In addition, the level of phosphorylated p38 MAPK, but not that of the phosphorylated ERK1/2, decreased in quercetin-pretreated group. These findings suggested that the protective effect of quercetin involved the inhibition of phosphorylated p38 MAP activity. Furthermore, quercetin could also preserve the functional integrity of ECV304 monolayers from H(2)O(2) exposure.
紧密连接是控制上皮/内皮屏障细胞旁通透性的关键结构。本研究探讨了槲皮素对 H2O2（过氧化氢）诱导的 ECV304 单层细胞紧密连接破坏和高通透性的保护作用。非致死浓度的 H2O2（100μmol/L；4 小时）降低了紧密连接蛋白封闭蛋白（occludin）和封闭蛋白-1（zonular occudens-1，ZO-1）的表达，并破坏了细胞边界的连接结构。同时，观察到细胞外信号调节激酶（extracellular signal-regulated kinase，ERK）1/2 和丝裂原活化蛋白激酶（mitogen-activated protein kinase，MAPK）p38 的活性增加。在 H2O2 处理前用槲皮素（10μmol/L；30 分钟）预处理可防止 ZO-1 和 occludin 的丢失。此外，在槲皮素预处理组中，磷酸化 p38MAPK 的水平降低，而磷酸化 ERK1/2 的水平没有降低。这些发现表明，槲皮素的保护作用涉及抑制磷酸化 p38MAP 活性。此外，槲皮素还可以防止 ECV304 单层细胞在 H2O2 暴露下的功能完整性受到破坏。
