武汉云克隆科技股份有限公司

Abstract:

The cytoprotective mechanisms of melatonin in hepatic ischemia/reperfusion (I/R) injury associated with heme oxygenase-1 (HO-1) induction and type 1 interferon (IFN) signaling pathway downstream of toll-like receptor 4 (TLR4) were investigated. Rats were subjected to 60min of ischemia followed by 5-hr reperfusion. Melatonin (10mg/kg) or vehicle (5% ethanol in saline) was administered intraperitoneally 15min prior to ischemia and immediately before reperfusion. Rats were pretreated with zinc protoporphyrin (ZnPP, 10mg/kg, i.p.), a HO-1 inhibitor, at 16 and 3hr prior to ischemia. Melatonin attenuated the I/R-induced increase in serum alanine aminotransferase activity, and ZnPP reversed this attenuation. Melatonin augmented the levels of HO activity and HO-1 protein and mRNA expression, and this enhancement was reversed by ZnPP. Melatonin enhanced the level of NF-E2-related factor-2 (Nrf2) nuclear translocation, and ZnPP reversed this increase. Overexpression of TLR4 and its adaptor proteins, toll-receptor-associated activator of interferon (TRIF), and myeloid differentiation factor 88 (MyD88), induced by I/R, was attenuated by melatonin; ZnPP reversed the effect of melatonin on TLR4 and TRIF expression. Melatonin suppressed the increased interaction between TLR4/TRIF and TLR4/MyD88, which was reversed by ZnPP. Melatonin attenuated the increased levels of JAK2 and STAT1 activation as well as IFN-β, and ZnPP reversed these inhibitory effects of melatonin. Melatonin inhibited the level of chemokine (C-X-C motif) ligand 10 (CXCL-10), and ZnPP reversed this inhibition. Our findings suggest that melatonin protects the liver against I/R injury by HO-1 overexpression, which suppresses the type 1 IFN signaling pathway downstream of TLR4.

摘要：

本文研究褪黑素对肝脏缺血/再灌注损伤的细胞保护机制与血红素加氧酶-1(HO-1)的诱导作用和Toll样受体4(TLR4)下游的1型干扰素(IFN)通路的转导机制。将实验动物大鼠缺血处理1小时在再灌注处理5小时。于缺血前15分钟及再灌注前立刻腹腔注射褪黑素(10mg/kg)或溶剂组(生理盐水含5%乙醇)。缺血前16小时和3小时，用HO-1抑制剂—锌原卟啉（ZnPP，10mg/kg）预处理大鼠。褪黑素能抑制I/R诱导血清丙氨酸转氨酶活性升高，而ZnPP则逆转褪黑素的抑制作用；褪黑素增强NF-E2相关因子-2(Nrf 2)核转运水平，而ZnPP则逆转褪黑素的促进作用；褪黑素能抑制I/R诱导的TLR4及其适配蛋白、干扰素Toll受体相关激活剂、髓系分化因子88（MyD88）的过表达，ZnPP逆转褪黑素对TLR 4和TRIF表达的影响；褪黑素抑制TLR 4/TRIF与TLR 4/MyD 88的相互作用，而ZnPP逆转两者的相互作用；褪黑素能抑制JAK 2和STAT 1以及IFN-β活性升高，而ZnPP则逆转褪黑素的抑制作用；褪黑素抑制趋化因子10(CXCL-10)的水平，ZnPP逆转褪黑素抑制作用。研究发现褪黑素通过抑制TLR4下游的1型IFN信号通路，保护肝脏免受HO-1过表达诱导的缺血/再灌注损伤。

使用试剂原文信息：Serum IFN-b and CXCL-10 levels were detected using commercially available IFN-b and CXCL-10 enzyme-linked immunosorbent assay (ELISA) kits (USCN Life Science Inc., Wuhan, China), respectively, according to the manufacturer’s protocols.