Trichosanatine alleviates oxidized low-density lipoprotein induced endothelial cells injury via inhibiting the LOX-1/p38 MAPK pathway

The LOX-1/p38 mitogen-activated protein kinase (MAPK) pathway has been proved to participate in the endothelial dysfunction in atherosclerosis. Trichosanatineis is an active compound isolated from the peel of Trichosanthes kirilowii. This study aims to determine whether trichosanatine prevents the oxidized low-density lipoprotein (ox-LDL)-induced insult through inhibition of the LOX-1/p38 MAPK pathway in HUVECs. HUVECs were treated with 150 mg/ml ox-LDL for 24 h to establish an ox-LDL-induced endothelial injury model. Cell viability, mitochondrial membrane potential (MMP), apoptosis, reactive oxygen species (ROS) level, LOX-1 and p38 MAPK expression level were measured. The results indicated that HUVECs were pretreated with either 100 mM trichosanatine or LOX-1 shRNA prior to exposure to ox-LDL for 24 h. Exposure of HUVECs to 150 mg/ml ox-LDL for 24 h significantly up-regulated the expression levels of LOX-1. The increased expression levels of LOX-1 were markedly attenuated by pretreatment with 100 mM trichosanatine. In addition, the ox-LDL-induced increase in phosphorylated (p) p38 MAPK expression was ameliorated by pretreatment with LOX-1 shRNA. Pretreatment of HUVECs with either trichosanatine or LOX-1 shRNA before exposure to ox-LDL significantly inhibited the ox-LDL-induced injuries, as evidenced by an increase in cell viability, a decrease in apoptotic cells, a ROS generation and a loss of MMP. In conclusion, we have demonstrated for the first time that the LOX-1/p38 MAPK pathway contributes to the ox-LDL-induced injury in HUVECs. Meanwhile, the trichosanatine protects the HUVECs against ox-LDL-induced injury at least in part by inhibiting the activated of LOX-1/p38 MAPK pathway.

LOX - 1 / p38丝裂原活化蛋白激酶（MAPK）通路已被证实参与动脉粥样硬化中的内皮功能障碍。天花粉蛋白是从栝楼皮中分离出的一种活性化合物。本研究旨在确定天花粉蛋白是否通过抑制人脐静脉内皮细胞（HUVECs）中的LOX - 1 / p38 MAPK通路来预防氧化低密度脂蛋白（ox - LDL）诱导的损伤。用150μg/ml ox - LDL处理HUVECs 24小时以建立ox - LDL诱导的内皮损伤模型。测量细胞活力、线粒体膜电位（MMP）、细胞凋亡、活性氧（ROS）水平、LOX - 1和p38 MAPK表达水平。结果表明，在暴露于ox - LDL 24小时之前，HUVECs用100μM天花粉蛋白或LOX - 1 shRNA进行预处理。HUVECs暴露于150μg/ml ox - LDL 24小时显著上调了LOX - 1的表达水平。用100μM天花粉蛋白预处理可显著减弱LOX - 1表达水平的升高。此外，用LOX - 1 shRNA预处理可改善ox - LDL诱导的磷酸化（p）p38 MAPK表达的增加。在暴露于ox - LDL之前，用天花粉蛋白或LOX - 1 shRNA预处理HUVECs可显著抑制ox - LDL诱导的损伤，表现为细胞活力增加、凋亡细胞减少、ROS产生减少以及MMP损失减少。总之，我们首次证明了LOX - 1 / p38 MAPK通路有助于HUVECs中ox - LDL诱导的损伤。同时，天花粉蛋白至少部分通过抑制LOX - 1 / p38 MAPK通路的激活来保护HUVECs免受ox - LDL诱导的损伤。