核因子IL-33调节肝脏巨噬细胞活性在乙型肝炎重症化过程中的作用研究

The pathogenesis of hepatitis B exacerbation is not virtually explored. The overwhelming activation of hepatic macrophages plays a critical role in the exacerbation of hepatitis B. Recent studies have shown that interleukin-33 (IL-33) acts as an endogenous damage-associated molecular pattern to regulate the activity of macrophages, playing an important role in the late stage of inflammatory response. However, the roles of self-derived IL-33 which acts as a nuclear factor in hepatic macrophages in the early stage of hepatitis B exacerbation are not clear. Our preliminary studies have shown that the serum levels of IL-33 were significantly expressed in patients with acute-on-chronic liver failure. In addition, a portion of IL-33 positive staining was observed around the inflammatory foci in patients with higher inflammatory grades, which showed a positive correlation with liver injury. The dynamic expression and the translocation of IL-33 in hepatic macrophages were investigated in patients with HBV infection. The roles of intracellular IL-33 in the immune phenotype, the antigen presenting function, the phagocyte function and the inflammatory properties of hepatic macrophages were determined in vitro. The impact of specific-regulation of IL-33 expression in macrophages on the exacerbation of hepatitis B was also assessed in vivo. We propose to establish a novel immunotherapy to treat hepatitis B exacerbation and to provide experimental evidence for early predicting and preventing hepatitis B exacerbation.

乙型肝炎重症化的机制仍未完全清楚。肝脏巨噬细胞早期持续而过度活化在乙肝重症化过程中发挥重要作用。最新研究发现，IL-33作为内源性损伤相关的模式分子调节巨噬细胞免疫活性，在晚期炎症反应中扮演重要角色。然而，IL-33作为核因子在乙肝重症化早期如何调控肝脏巨噬细胞的活性仍不清楚。我们前期研究发现，慢加急性肝衰竭乙肝患者血清IL-33水平显著升高，IL-33在乙肝炎症坏死灶中高表达，与乙肝重症化时肝脏炎症损伤程度密切相关。本课题拟研究不同临床分型乙肝患者血清IL-33水平及其在肝脏巨噬细胞中的表达和转位情况，体外研究核因子IL-33对肝脏巨噬细胞免疫表型、递呈功能、吞噬功能以及炎症因子分泌的调控作用及分子机制，体内探索特异性调控肝脏巨噬细胞中IL-33的表达对乙肝重症化过程的影响，建立以巨噬细胞为靶标的免疫治疗方法，抑制其过度活化状态，阻止乙肝重症化的进展，为乙肝重症化的早期诊治提供新依据。

单核巨噬细胞群在乙型肝炎重症化发生发展中的作用仍不十分清楚，IL-33作为损伤相关的模式分子（DAMP）调控单核巨噬细胞群的免疫活性，在乙肝重症化过程中起重要作用。通过检测不同临床类型乙肝感染者的血清和肝穿组织标本中IL-33的表达，发现与乙肝病毒携带者和慢乙肝患者相比，慢加急性肝衰竭患者血清中IL-33 的水平显著升高，且与终末期肝病评分系统MELD和CLIF-SOFA呈正相关。此外，肝穿刺标本免疫组化结果显示：正常肝脏组织切片IL-33阳性细胞主要见于肝血窦处，随着肝脏炎症加重，IL-33 表达增强，范围变广，在肝血窦、肝实质细胞以及炎症坏死灶中均有IL-33高表达。在细胞水平研究发现，IL-33在内毒素环境下，通过促进单核巨噬细胞HLA-DR、CCR2 和CD80表达，增强单核巨噬细胞抗原递呈功能；IL-33通过增强ERK1/2磷酸化水平促进单核巨噬细胞中前炎症因子如TNF-α、IL-6和IL-1β释放。动物体内研究发现，特异性耗竭巨噬细胞，显著减轻内毒素致敏/半乳糖胺肝衰竭小鼠肝脏炎症反应，除此以外，靶向性干扰巨噬细胞IL-33的表达可部分缓解该模型小鼠肝脏的炎症反应，提高了该模型小鼠的生存率。综上所述，本研究系统探讨DAMP分子IL-33对于判断慢乙肝重症化进展的临床价值，为临床使用该指标早期预测乙肝肝衰竭提供循证学依据；发现IL-33促进单核巨噬细胞呈递抗原的能力，在内毒素环境下，协同促进致炎症因子的释放，这是继病毒特异性免疫损伤、肠源性内毒素血症后，IL-33作为内源性DAMP分子对肝脏的第三重打击，靶向性调节巨噬细胞中的IL-33可遏制肝脏炎症进展，以上结果为乙肝重症化的早期诊治提供新依据新思路。