High-mobility group box-1 and alcoholic liver disease

摘要 酒精性肝病(ALD)领域取得进展的一个关键障碍是缺乏对关键因素的了解 促炎症介质及其驱动肝损伤的机制。高移动性组盒-1 (HMGB1)是一种损伤相关的分子模式，它将炎症传递并放大到 相邻的细胞。支持这一应用的初步研究表明，HMGB1增加，经历后 翻译修饰，并在酒精中毒患者和ALD小鼠模型中分泌。我们确认了 肝细胞和Kupffer细胞都能产生完全还原和乙酰化的HMGB1，而肝细胞是 氧化HMGB1的主要来源。我们发现，有条件地消融肝细胞或髓细胞中的HMGB1 在防止炎症、白介素1β(IL1β)的产生和酒精性肝病中部分保护而同时缺失。 同样，髓系细胞中晚期糖基化终产物(RAGE)的HMGB1受体被敲除 保护免受ALD的伤害。我们已经证实，在酒精中毒患者中，氧化的HMGB1与IL-1β形成一个复合体。 在老鼠身上。总体而言，HMGB1促进了免疫细胞的渗透，激活了NFκB，增加了促炎因子 细胞因子白介素1β，所有与肌萎缩侧索硬化症的发生和发展有关的中心事件。而HMGB1亚型似乎 有不同的影响；然而，它们中每一种对酒精诱导的炎症和IL1β的确切贡献 产量仍未确定。我们认为，乙酰化和氧化的HMGB1水平调节 酒精暴露后炎性细胞浸润。这些异构体也可以驱动键的表达 核因子κB靶向致炎细胞因子IL-1β。由于氧化的HMGB1与IL1β形成络合物，因此它可能是 免疫刺激和增强RAGE和/或IL1R信号。这可能特别相关，因为两者都 分子在ALD的发病机制中起着中心作用。然而，还需要进一步了解这些亚型是如何形成的 导致免疫细胞渗透，涉及的关键受体，它们的结合亲和力，以及它们本身或通过 IL-1β免疫刺激复合体促进核因子κ-B诱导IL-1β基因表达并最终成熟IL-1β ALD中的蛋白质。我们的中心假设是乙酰化和氧化的HMGB1水平调节 酒精性肝病的炎性细胞浸润和IL-1β的产生。计划有两个具体目标来证明这一假设。 在目标1中，我们将剖析酒精介导的hmgb1亚型增加如何调节炎症细胞。 渗入肝脏。在目标2中，我们将确定HMGB1亚型的受体结合亲和力，如果 它们本身发出信号或与IL-1β形成免疫刺激复合物，以驱动NF-κ-B诱导IL-1βm RNA和 白介素1β蛋白在酒精性肝病中的成熟我们的长期目标是剖析HMGB1亚型的致病作用 作为预防ALD的潜在治疗靶点。

ABSTRACT A critical barrier to progress in the field of alcoholic liver disease (ALD) is the lack of knowledge on the key proinflammatory mediators and the mechanisms whereby they drive liver injury. High-mobility group box-1 (HMGB1) is a damage-associated molecular pattern that communicates and amplifies inflammation to neighboring cells. Preliminary studies supporting this application reveal that HMGB1 increases, undergoes post- translational modifications and is secreted in alcoholic patients and mouse models of ALD. We identified that both hepatocytes and Kupffer cells produce fully reduced and acetylated HMGB1 whereas hepatocytes are the main source of oxidized HMGB1. We show that conditional ablation of Hmgb1 in hepatocytes or myeloid cells partially protects while deletion in both prevents inflammation, interleukin-1β (IL1β) production and ALD. Likewise, knockdown of the HMGB1 receptor for advanced glycation end-products (RAGE) in myeloid cells protects from ALD. We have identified that oxidized HMGB1 forms a complex with IL1β in alcoholic patients and in mice. Overall, HMGB1 drives immune cell infiltration, activates NFκB and increases the proinflammatory cytokine IL1β, all central events for the onset and progression of ALD. While the HMGB1 isoforms appear to have distinct effects; yet, the precise contribution of each one of them to alcohol-induced inflammation and IL1β production remains undefined. We believe that the levels of acetylated and oxidized HMGB1 regulate inflammatory cell infiltration upon alcohol exposure. These isoforms may also drive the expression of the key NFκB target proinflammatory cytokine IL1β. Since oxidized HMGB1 forms a complex with IL1β, it could be immunostimulatory and enhance RAGE and/or IL1R signaling. This may be particularly relevant as both molecules are central to the pathogenesis of ALD. Yet, further understanding is needed on how the isoforms lead to immune cell infiltration, the key receptor involved, their binding affinity and if they signal per se or via immunostimulatory complexes with IL1β to drive NFκB induction of Il1β mRNA and ultimately maturation of IL1β protein in ALD. Our central hypothesis is that the levels of acetylated and oxidized HMGB1 regulate inflammatory cell infiltration and IL1β production in ALD. Two specific aims are planned to prove this hypothesis. In Aim 1, we will dissect how the alcohol-mediated increase in the HMGB1 isoforms regulates inflammatory cell infiltration into the liver. In Aim 2, we will determine the receptor binding affinity of the HMGB1 isoforms and if they signal per se or form immunostimulatory complexes with IL1β to drive NFκB induction of Il1β mRNA and maturation of IL1β protein in ALD. Our long-term goal is to dissect the pathogenic role of the HMGB1 isoforms as potential therapeutic targets to prevent ALD.