基于TLR4-MyD88-TRAF6信号通路的儿茶素没食子酸酯抗小神经胶质细胞炎性损伤作用

Effects of epigallocatechin gallate against inflammatory injury in microglia based on TLT4-MyD88-TRAF6 signaling pathway

关键词:  没食子酸酯  小神经胶质细胞  炎症  信号通路

Key words:  epigallocatechin gallate  microglia  inflammation  signal pathway

摘要:

[目的]研究儿茶素没食子酸酯（EGCG）对小神经胶质细胞（BV-2）炎性损伤的保护作用，并探讨其对TLR4-MyD88-TRAF6信号通路活化的影响。[方法]采用脂多糖（LPS，1 mg/L）体外诱导BV-2细胞炎性损伤，将细胞分为正常对照组、LPS诱导组、LPS+低剂量（50 μmol/L）EGCG组、LPS+中剂量（100 μmol/L）EGCG组、LPS+高剂量（200 μmol/L）EGCG组；CCK8法检测BV-2细胞相对存活率，ELISA法检测炎性因子白介素6（IL-6）、白介素1β（IL-1β）及肿瘤坏死因子-α（TNF-α）水平，Western Blot方法分析诱生型一氧化氮合酶（iNOS）、前列腺素内氧化酶还原酶（COX-2）、Toll样受体4（TLR4）、髓样分化因子88（MyD88）及TNF-α相关受体因子6（TRAF6）蛋白表达。[结果]与LPS诱导组相比，不同浓度EGCG干预的BV-2细胞相对存活率明显升高（P<0.05），细胞上清炎性因子IL-6、IL-1β及TNF-α水平明显降低（P<0.05），细胞中炎性蛋白iNOS及COX-2表达水平显著降低（P<0.05）；细胞中TLR4、MyD88及TRAF6蛋白表达也显著降低（P<0.05），并表现出剂量依赖性。[结论]EGCG能显著抑制LPS诱导的BV-2细胞炎症损伤，抑制炎症相关蛋白的表达，其可能作用机制是通过抑制TLR4-MyD88-TRAF6信号通路活化。

Abstract:

[Objective] To observe the protective effects of epigallocatechin gallate (EGCG) on inflammatory injury in microglia,and investigate the effect of EGCG on the activation of TLT4-MyD88-TRAF6 signaling pathway.[Methods] LPS was used to induce the model of inflammatory injury in BV-2 cells in vitro. BV-2 cells were divided into five groups,including control group,LPS induced group,LPS+low dose (50 μmol/L) EGCG group,LPS+middle dose (100 μmol/L) EGCG group,and LPS+high dose (200 μmol/L) EGCG group. CCK8 assay was used to measure the relative survival rates of BV-2 cells. ELISA assay was used to detect the levels of interleukin 6 (IL-6),interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α). Western Blot was used to determine the expression levels of induced nitric oxide synthase (iNOS),cyclooxygenase (COX-2),Toll like receptor 4 (TLR4),Myeloid differentiation factor of 88 (MyD88) and tumor necrosis factor receptor related factor of 6 (TRAF6) proteins.[Results] Compared with control group,the relative survival rates of BV-2 cells were greatly icreased after treatment with different concentrations of EGCG (P<0.05). The levels of inflammatory factors (IL-6,IL-1β and TNF-α) were significantly decreased (P<0.05). The expression levels of iNOS,COX-2,TLT4,MyD88 and TRAF6 were also greatly decreased (P<0.05) with a dose-dependent manner.[Conclusion] EGCG can significantly inhibit the inflammatory response of BV-2 microglial cells induced by LPS via suppressing the activation of TLT4-MyD88-TRAF6 signaling pathway.