细胞外组蛋白在重型肝炎发病中的作用及分子机制研究

Acute liver failure occurs in a variety of medical conditions and causes higher mortalities. It has been suggested that secondary inflammation and immunological disorders, following primary hepatocyte damage caused by viruses (HBV/HCV), alcohol, drug or chemical toxins, play a vital role in the initiation of acute hepatic failure. But the underlying molecular mechanisms remain largely unclear. Recently, extracellular histones have been identified as a new DAMP (Damage Associated Molecular Pattern) molecule and exhibited to be a major mediator of death in sepsis. In our pilot study, we found that extracellular histones were significantly released in the circulation of GalN/LPS-treated mice in a time-dependent manner, which likely contributed to the increase of inflammatory cytokines and the death of mice. Neutralization of histones by specific anti-histones antibodies strikingly improved the survival rate of GalN/LPS-treated mice. It thus indicated a dual role of extracellular histones either as a cell death marker for acute liver failure or as a new therapeutic target in the treatment of hepatic injury. In the present study, we aim to investigate the profile of extracellular histones levels following acute liver damage in in vivo and in vitro models as well as in clinical patients with severe liver failure. Moreover, the molecular pathways of extracellular histones involved in activation of innate immunity and inflammatory events will be examined. Most importantly, we will explore the protective effects and the potential therapeutic significance of specific anti-histones antibodies, which may serve as a new strategy in the treatment of acute liver failure. Our study will shed light on the pathogenesis of severe liver damage and provide valuable information for exploring its biomarker and therapeutic potential.

重型肝炎病因复杂，病死率极高；继发性炎症反应和免疫功能紊乱在肝炎重症化转变中可能起关键作用，但具体机制不明。我们前期工作发现，一种新发现的"损伤相关分子模式"（DAMP）分子－细胞外组蛋白与肝脏炎症损伤反应密切相关，并可能是激活天然免疫细胞、诱发异常免疫反应的关键介质，特异性抗组蛋白抗体能显著减轻小鼠急性肝损伤，这为重肝的机制研究和治疗靶点探索等开辟了新的方向。本项目拟建立多病因的重肝动物和细胞模型，并结合临床重肝病人资料，重点研究细胞外组蛋白的变化情况及干预效果，以及与细胞凋亡、免疫细胞活化和炎症信号通路激活等事件的关系，从上游早期损伤事件、信号传导通路（TLR等）和下游代谢产物（炎性因子TNF-a等）等不同角度深入探讨细胞外组蛋白在重肝发病中的作用及分子机制，并给予干预措施验证假说。本研究将在更深层面揭示重肝发病的一些关键问题或核心关节，并为临床早期预警和干预治疗等提供科学线索。

本课题为一年期的专项基金项目。我们课题设计是以细胞外组蛋白为切入点，通过建立D-氨基半乳糖联合脂多糖的方法诱导小鼠急性肝损伤模型，探讨细胞外组蛋白的变化规律，以及与细胞凋亡、中性粒细胞活化和炎症细胞因子等指标的相关性。大量研究发现，失控的炎症反应和免疫功能紊乱在肝炎重症化转变中可能起关键作用，针对这个环节进行研究可能会取得突破性进展。细胞外组蛋白是新近发现的一种炎症信号分子。我们的工作证实，细胞外组蛋白在急性肝损伤发病过程中显著升高，并可能是激活天然免疫细胞、诱发异常免疫反应的关键介质。我们给予染毒小鼠外源性组蛋白和特异性抗组蛋白中和抗体进行干预，以验证细胞外组蛋白的炎性作用。与此同时，我们还收集了临床重肝病例的血浆标本，检测细胞外组蛋白的水平，分析是否与疾病严重程度、预后等相关。本课题证实了细胞外组蛋白在急性肝损伤的发病中确具关键作用，特异性中和抗体有明显的保护作用，从而为临床干预治疗肝损伤提供重要的实验依据。在下一步的工作中，我们将制备不同病因的急性肝损伤模型，探索细胞外组蛋白的变化规律，以及利用体外实验，深入探索细胞外组蛋白的分子机制。本项目经过一年的工作，现已发表2篇中文和1篇英文SCI论著（影响因子3分），均标注了本项目的资助。