microRNA在日本血吸虫虫源蛋白抑制肝纤维化中的作用及机制研究

microRNA plays an important role in the development and in the reversal process of hepatic fibrosis. Our preliminary researches showed that microRNA-454 could inhibit activation of hepatic stellate cells (HSCs) by targeting Smad4 in mice infected with Schistosoma japonicum. We also found that Schistosoma japonicum -derived proteins could inhibit HSC activation and induce HSC apoptosis and then induce the regression of hepatic fibrosis in advanced schistosomiasis. However, whether microRNA can participate in the Schistosoma japonicum-derived proteins-induced reversal of hepatic fibrosis has not yet been reported. Hence, gene chip technology is used in this study to screen microRNAs that differentially expressed in Schistosoma japonicum-derived proteins-incubated HSCs and in the livers with advanced schistosomiasis. Further studies will be focused on the effects of these differentially expressed microRNAs and the associated targets in the inhibition of hepatic fibrosis induced by Schistosoma japonicum -derived proteins. We will also explore the potential mechanisms by which these differentially expressed microRNAs and the associated targets can modulate hepatic fibrosis. Desired outcomes will provide the potential target that could prevent the development of liver fibrosis.

microRNA在肝纤维化的发生发展以及肝纤维化逆转过程中发挥着重要作用。我们前期研究结果表明在血吸虫病小鼠肝组织中，microRNA-454能够通过靶向Smad4基因参与抑制肝星状细胞活化。同时，日本血吸虫虫源蛋白能够通过抑制肝星状细胞活化、促进肝星状细胞凋亡等机制，使血吸虫病晚期肝纤维化发生逆转。然而，在日本血吸虫虫源蛋白抑制肝纤维化过程中，microRNA是否参与抑制过程，尚未见报道。本研究将利用基因芯片技术筛选日本血吸虫虫源蛋白（SEA，SjP40等）诱导肝星状细胞的过程中以及日本血吸虫病晚期肝纤维化逆转相关差异表达的microRNA，进一步观察相关microRNA及靶基因在虫源蛋白抑制肝纤维化中的作用并探索其分子机制。本项目的预期结果将为肝纤维化防治提供新的潜在靶点。

日本血吸虫虫源蛋白能够抑制肝星状细胞（HSCs）活化，然而，microRNAs是否参与该活化抑制过程以及其机制如何均未见报道。因此，为了探索日本血吸虫虫源蛋白抑制 HSCs活化过程中microRNAs的表达及作用，本项目首先筛选了重组日本血吸虫虫卵P40蛋白（rSjP40）抑制HSCs活化过程中差异表达的microRNAs，随后观察了在rSjP40抑制HSCs活化过程中差异表达microRNAs及其靶基因的作用；并进一步探索差异表达的microRNAs在rSjP40抑制HSCs活化中的作用机制。结果表明，rSjP40能够促进人HSCs 株LX-2细胞中miR-146a、miR-146b、miR-155、let-7b及let-7d的表达，抑制LX-2细胞中miR-27b的表达；rSjP40通过miR-146a/Smad4通路抑制LX-2细胞中I型胶原蛋白的表达；rSjP40通过诱导miR-27b甲基化从而诱导LX-2细胞中PPARγ表达；rSjP40也能够通过抑制LX-2细胞中转录因子STAT5表达诱导miR-155启动子活性，并进一步抑制miR-155靶基因FOXO3a的表达，从而抑制LX-2细胞中I型胶原蛋白和α-SMA的表达。以上结果提示，miR-146a/Smad4、 miR-27b/PPARγ以及STAT5/miR-155/FOXO3a信号通路可能作为治疗血吸虫病等致病因素所致肝纤维化的新潜在靶点。