PM2.5诱导miRNA参与调控非酒精性脂肪肝代谢酶CYP3A4功能的机制研究

Nonalcoholic fatty liver disease (NAFLD) is now the most common cause of chronic liver disease. Studies have shown that fine particulate matter (PM2.5) exposure could induce and aggravate NAFLD. However, the mechanism of how PM2.5 affects the pathogenesis of NAFLD and CYP3A4 function remains largely unknown. CYP3A4 is the most abundant CYP450 enzyme in the human liver and intestine. Our previous study showed that CYP3A4 expression decreased dramatically after PM2.5 exposure in NAFLD cell model, which was possibly regulated through miR-200a and miR-150. Therefore, we hypothesize here that PM2.5 inhibits the expression and function of PXR/CYP3A4 in nonalcoholic fatty liver disease through direct and indirect modulations of miRNAs. We intend to carry out a prospective study on PM2.5 exposure, PXR and CYP3A4 expression and function in NAFLD patients. Additionally, PM2.5 exposure-induced NAFLD model will be established in PXR-/- mice and humanized PXR mice to determine the impact of PM2.5 on the key components of PXR/CYP3A4 pathway, and to further demonstrate how PM2.5 regulates PXR/CYP3A4 expression and function through miRNAs or histone modifications. Together, we expect to clarify the molecular mechanisms of liver injury in PM2.5 exposure-induced NAFLD, which will provide theoretical basis for optimized therapeutic strategies for NAFLD patients.

非酒精性脂肪肝病（NAFLD）是国内外最常见的慢性肝病，研究显示大气细颗粒物（PM2.5）可诱发和加剧NAFLD，但具体机制及对肝代谢酶功能的影响尚不清楚。CYP3A4是人体最重要的药物代谢酶。我们前期发现PM2.5暴露可显著下调脂肪肝细胞模型的CYP3A4表达，与miR-200a/miR-150的调控有关。由此提出假说：PM2.5通过miRNA直接或间接影响PXR/CYP3A4信号通路，从而导致NAFLD肝代谢酶功能和活性损伤。我们拟开展NAFLD人群PM2.5暴露与PXR/CYP3A4前瞻性研究；利用PXR-/-小鼠和人源PXR小鼠建立PM2.5诱导的NAFLD模型，探索miRNA对PXR/CYP3A4通路关键环节的调节效应，以期揭示PM2.5调控NAFLD肝代谢酶CYP3A4功能的表观遗传学机制，为NAFLD人群的合理用药提供理论依据。

非酒精性脂肪性肝病（NAFLD）是国内外最常见的慢性肝病。研究表明细颗粒物（PM2.5）是NAFLD发生的风险因子，但是具体的机制及对肝代谢酶功能的影响并不清楚。.为了明确PM2.5对NAFLD表型的诱导作用，我们构建了法尼酯X受体敲除小鼠（FXR-/-）NAFLD模型，暴露于高浓度PM2.5环境8周，来探讨PM2.5对小鼠肝脏脂肪变性的影响。结果发现亚急性暴露于PM2.5可引起轻度的肝脏脂肪变性。急性气管滴注PM2.5可引起野生型小鼠肝脏甘油三酯(TG)和总胆固醇(TC)含量升高。然而，暴露于PM2.5的FXR-/-小鼠与清洁环境生活的FXR-/-小鼠的TG和TC含量无统计学差异。提示FXR介导了PM2.5诱导的肝脏脂肪变性。二代测序方法对肝脏转录组测序（RNA­seq）分析，发现PM2.5诱导的肝脂肪变性可能与肝脏免疫反应功能改变有关，差异基因功能较多富集在生物过程中的免疫反应上，信号通路则较多富集在NFκB等炎症通路上，印证了本研究的潜在价值。.为了进一步明确PM2.5暴露对CYP3A4与miRNA之间的调控机制，细胞实验发现CYP3A4表达下调，miRNA-200a-3p和miRNA-150-5p表达上调，双荧光素酶分析证实miR-200a-3p和miR-150-5p都以CYP3A4的3‘-UTR区为靶点，且其相互作用可被CYP3A4的3’-UTR区的miRNA结合位点突变所消除。利用miRNA-200a-3p和miR-150-5p的模拟物或抑制剂，证实了内源性CYP3A4受到miR-200A-3p或miR-150-5p转录后调控。此外，miR-200a-3p和miR-150-5p抑制剂依赖于CYP3Y4的表达减轻FFA诱导的L02细胞脂肪变性。这些结果提示miR-200a-3p和miR-150-5p通过直接靶向CYP3A4的3‘-UTR参与了FFA诱导的脂肪变性的发生。.我们的研究揭示了FXR在PM2.5暴露诱导的肝脂肪变性过程中的重要作用，且PM2.5暴露可通过miRNA等表观遗传学机制诱导NAFLD肝酶CYP3A4代谢功能。共发表论文12篇，其中中文论文4篇，英文SCI论文8篇，授权专利1项，软件著作权2项，获得湖南省科技进步奖二等奖1项。本研究结果有望为NAFLD人群的合理用药和雾霾健康风险防范提供理论依据。