Lei Qi, Qiang Fu, Chao Du, Di Wu, Guoqian Zhang, Bo Yuan, Lina Yan
Department of ICU, Tianjin Huanhu Hospital, Tianjin, P.R. China.
Department of ICU, Tianjin 4th Central Hospital, Tianjin, P.R. China.
Int J Mol Med. 2014 Dec;34(6):1629-39. doi: 10.3892/ijmm.2014.1965. Epub 2014 Oct 13.
Intestinal barrier dysfunction occurs in critical illnesses and involves the inflammatory and hypoxic injury of intestinal epithelial cells. Researchers are still defining the underlying mechanisms and evaluating therapeutic strategies for restoring intestinal barrier function. The anti-inflammatory drug, emodin, has been shown to exert a protective effect on intestinal barrier function; however, its mechanisms of action remain unknown. In this study, we investigated the protective effects of emodin on intestinal barrier function and the underlying mechanisms in intestinal epithelial cells challenged with lipopolysaccharide (LPS) and hypoxia/reoxygenation (HR). To induce barrier dysfunction, Caco-2 monolayers were subjected to HR with or without LPS treatment. Transepithelial electrical resistance and paracellular permeability were measured to evaluate barrier function. The expression of the tight junction (TJ) proteins, zonula occludens (ZO)-1, occludin, and claudin-1, as well as that of hypoxia-inducible factor (HIF)-1α, phosphor-IκB-α, phosphor-nuclear factor (NF)-κB p65 and cyclooxygenase (COX)-2 was determined by western blot analysis. The results revealed that emodin markedly attenuated the decrease in transepithelial electrical resistance and the increase in paracellular permeability in the Caco-2 monolayers treated with LPS and subjected to HR. Emodin also markedly alleviated the damage caused by LPS and HR (manifested by a decrease in the expression of the TJ protein, ZO-1), and inhibited the expression of HIF-1α, IκB-α, NF-κB and COX-2 in a dose-dependent manner. In conclusion, our data suggest that emodin attenuates LPS- and HR-induced intestinal epithelial barrier dysfunction by inhibiting the HIF-1α and NF-κB signaling pathways and preventing the damage caused to the TJ barrier (shown by the decrease in the expression of ZO-1).
肠屏障功能障碍发生于危重症中，涉及肠上皮细胞的炎症和缺氧损伤。研究人员仍在确定其潜在机制，并评估恢复肠屏障功能的治疗策略。抗炎药物大黄素已被证明对肠屏障功能具有保护作用；然而，其作用机制尚不清楚。在本研究中，我们研究了大黄素对脂多糖（LPS）和缺氧/复氧（HR）刺激的肠上皮细胞肠屏障功能的保护作用及其潜在机制。为诱导屏障功能障碍，将Caco-2单层细胞进行有或无LPS处理的HR处理。测量跨上皮电阻和细胞旁通透性以评估屏障功能。通过蛋白质印迹分析测定紧密连接（TJ）蛋白、闭合蛋白（ZO）-1、闭合蛋白和Claudin-1以及缺氧诱导因子（HIF）-1α、磷酸化IκB-α、磷酸化核因子（NF）-κB p65和环氧化酶（COX）-2的表达。结果显示，大黄素显著减轻了LPS处理并经历HR的Caco-2单层细胞中跨上皮电阻的降低和细胞旁通透性的增加。大黄素还显著减轻了LPS和HR造成的损伤（表现为TJ蛋白ZO-1表达降低），并以剂量依赖性方式抑制HIF-1α、IκB-α、NF-κB和COX-2的表达。总之，我们的数据表明，大黄素通过抑制HIF-1α和NF-κB信号通路并防止对TJ屏障造成的损伤（表现为ZO-1表达降低），减轻LPS和HR诱导的肠上皮屏障功能障碍。
