High-mobility group box-1 and alcoholic liver disease

摘要 酒精性肝病（ALD）领域进展的一个关键障碍是缺乏对酒精性肝病（ALD）关键因素的了解。 促炎介质及其驱动肝损伤的机制。高迁移率族蛋白B1 （HMGB1）是一种损伤相关的分子模式，它传递并放大炎症， 相邻的细胞。支持这一应用的初步研究表明，HMGB1增加，经历后， 在酒精中毒患者和ALD的小鼠模型中分泌。我们发现 肝细胞和库普弗细胞都产生完全还原和乙酰化的HMGB1，而肝细胞是 氧化型HMGB1的主要来源。我们发现，在肝细胞或骨髓细胞中条件性切除Hmgb1， 部分保护，而两者的缺失防止炎症、白细胞介素-1 β（IL 1 β）产生和ALD。 同样，敲低骨髓细胞中晚期糖基化终产物（AGEs）的HMGB1受体， 保护ALD。我们已经发现，在酒精中毒患者中，氧化的HMGB1与IL 1 β形成复合物， 对小鼠总体而言，HMGB1驱动免疫细胞浸润，激活NF κ B并增加促炎性细胞因子的表达。 细胞因子IL 1 β，所有ALD发作和进展的中心事件。虽然HMGB1亚型似乎 具有不同的作用;然而，它们中的每一个对酒精诱导的炎症和IL 1 β的精确贡献 生产尚未确定。我们认为乙酰化和氧化的HMGB1水平调节了 炎症细胞浸润。这些异构体也可能驱动关键的表达 NF κ B靶向促炎细胞因子IL 1 β。由于氧化的HMGB1与IL 1 β形成复合物， 免疫刺激和增强的IL1R和/或IL1R信号传导。这可能特别重要，因为 分子是ALD发病机制的核心。然而，还需要进一步了解异构体 导致免疫细胞浸润，涉及的关键受体，它们的结合亲和力，以及它们本身或通过 与IL 1 β形成免疫刺激复合物，驱动NF κ B诱导IL 1 β mRNA并最终使IL 1 β成熟 蛋白质ALD我们的中心假设是乙酰化和氧化的HMGB1水平调节了 ALD中炎性细胞浸润和IL 1 β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亚型的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， 它们本身发出信号或与IL 1 β形成免疫刺激复合物，以驱动NF κ B诱导IL 1 β mRNA， ALD中IL 1 β蛋白的成熟。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.