Jiang Weiwei, Liu Juan, Dai Yanyan, Zhou Nan, Ji Chenling, Li Xiaonan
Institute of Pediatric Research, Nanjing Children's Hospital Affiliated to Nanjing Medical University, Nanjing, China; Department of Neonatal Surgery, Nanjing Children's Hospital Affiliated to Nanjing Medical University, Nanjing, China.
J Gastroenterol Hepatol. 2015 May;30(5):933-43. doi: 10.1111/jgh.12878.
Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. In this study, we investigated the role of miR-146b in the Toll-like receptor-4 signaling pathway and high-fat diet (HFD)-induced NASH in vivo and in vitro.
The effect of miR-146b on the expression of IL-1 receptor-associated kinase 1 (IRAK1) and tumor necrosis factor receptor-associated factor 6 (TRAF6) in RAW264.7 cells and HepG2 was studied, and the effect of miR-146b on lipid accumulation in HepG2 was also studied in vitro. The levels of IRAK1, TRAF6, NF-κB, and pro-inflammatory cytokines, as well as the histologic features and lipid accumulation in the livers of HFD-induced non-alcoholic steatohepatitis (NASH) and an miR-146b-administered HFD mouse model, were studied in vivo.
After miR-146b administration, TRAF6 and IRAK1 mRNA and protein levels in macrophages after lipopolysaccharide administration and in HepG2 cells after oleic acid (OA) administration were significantly decreased in 146b group compared with control group (P < 0.001). The lipid accumulation in HepG2 cells exposed to OA was also decreased by inactivation of IRAK1 and TRAF6, then downregulation of the downstream molecules (NF-κB) and upregulation of the tension homolog deleted on chromosome 10 (PTEN) level. In vivo, after administration of miR-146b, TRAF6 and IRAK1 mRNA and protein levels as well as TNF-α and IL-6 mRNA and protein levels were decreased, and hematoxylin and eosin staining showed that the 146b group had low average adipose cell cross-sectional areas compared with control group.
MiR-146b ameliorated HFD-induced NASH by directly suppressing IRAK1 and TRAF6.
非酒精性脂肪性肝病（NAFLD）是全球最常见的慢性肝病之一。在本研究中，我们在体内和体外研究了miR-146b在Toll样受体4信号通路及高脂饮食（HFD）诱导的非酒精性脂肪性肝炎（NASH）中的作用。
研究miR-146b对RAW264.7细胞和HepG2中白细胞介素-1受体相关激酶1（IRAK1）和肿瘤坏死因子受体相关因子6（TRAF6）表达的影响，以及miR-146b对HepG2细胞脂质积累的体外影响。在体内研究了IRAK1、TRAF6、核因子κB（NF-κB）和促炎细胞因子的水平，以及HFD诱导的非酒精性脂肪性肝炎（NASH）小鼠模型和给予miR-146b的HFD小鼠模型肝脏的组织学特征和脂质积累情况。
给予miR-146b后，与对照组相比，146b组脂多糖给药后巨噬细胞以及油酸（OA）给药后HepG2细胞中TRAF6和IRAK1的mRNA和蛋白水平显著降低（P＜0.001）。IRAK1和TRAF6失活，随后下游分子（NF-κB）下调以及10号染色体缺失的张力蛋白同源物（PTEN）水平上调，也使暴露于OA的HepG2细胞中的脂质积累减少。在体内，给予miR-146b后，TRAF6和IRAK1的mRNA和蛋白水平以及肿瘤坏死因子-α（TNF-α）和白细胞介素-6（IL-6）的mRNA和蛋白水平降低，苏木精-伊红染色显示，与对照组相比，146b组平均脂肪细胞横截面积较小。
MiR-146b通过直接抑制IRAK1和TRAF6改善HFD诱导的NASH。
