Milk osteopontin, a nutritional therapeutic intervention for alcoholic hepatitis

描述(申请人提供)：酒精性肝炎是世界范围内肝脏疾病和死亡的主要原因；因此，迫切需要开发新的治疗干预措施。酒精性肝炎的发生和发展的关键事件是肠道到肝脏的相互作用。维生素D缺乏症在酒精性肝炎患者中非常普遍。补充维生素D可以调节紧密连接蛋白的表达，增强肠道的抗微生物防御能力，并减少肠道中的促炎细胞因子。维生素D通过骨桥蛋白启动子中的维生素D反应元件靶向骨桥蛋白。牛奶骨桥蛋白通过维持上皮屏障功能、提供粘膜防御、防止脓毒症和炎症反应来保护肠道。到目前为止，维生素D和骨桥蛋白在预防酒精性肝炎方面的联系还没有确定。我们认为使用维生素D和牛奶骨桥蛋白的营养疗法可以预防酒精性肝损伤。在本申请中，我们将重点检验“补充维生素D或牛奶骨桥蛋白可通过骨桥蛋白的肠道保护和抗脂肪作用预防酒精性肝炎”这一中心假设。特别是，我们假设维生素D和牛奶骨桥蛋白将：1)靶向肠道-肝轴，保护肠粘膜屏障，阻止革兰氏阴性菌从肠道转移到门静脉循环，从而降低脂多糖水平；2)通过靶向脂肪酸代谢，减少脂多糖介导的Kupffer细胞激活和TNFβ的产生，防止脂肪变性和肝脏损伤；以及3)通过增加自噬来避免肝脏脂肪变性、炎症和肝损伤，自噬是最近发现的一种调节脂肪变性的途径。我们将开发新的体内酒精性肝炎模型，以进一步了解肝损伤的机制。利用这些模型，小鼠将接受维生素D或牛奶骨桥蛋白治疗，以评估它们的治疗潜力。为了证明我们的假设，我们计划了三个具体目标。在目标1中，我们将分析维生素D和牛奶骨桥蛋白是否能阻断乙醇介导的肠道通透性、细菌易位和脂多糖利用率的增加。慢性Lieber-DeCarli模型和葡聚糖硫酸钠治疗将被使用。在目标2中，首先，我们将确定维生素D和牛奶骨桥蛋白是否通过靶向脂肪酸代谢来抑制脂肪变性；其次，我们将剖析骨桥蛋白与脂多糖结合的能力是否会降低库普弗细胞的激活、肿瘤坏死因子的产生以及其他促炎细胞因子。慢性Lieber-DeCarli模型和葡聚糖硫酸钠或脂多糖治疗将被使用。在目标3中，将开发一种新的基于自噬阻断的酒精性肝炎模型。接下来，我们将确定维生素D和牛奶骨桥蛋白是否通过激活自噬途径而减少脂肪变性，而不依赖于靶向细菌易位或结合内毒素。因此，本申请的总体目标是调查饮食中给予维生素D和牛奶骨桥蛋白是否可以成为减缓或防止酒精性肝炎进展的一种有效的低成本治疗策略。

DESCRIPTION (provided by applicant): Alcoholic hepatitis is a leading cause of liver disease and death worldwide; thus, there is an urgent need to develop novel therapeutic interventions. Key events for the onset and progression of alcoholic hepatitis result from the gut-to-liver interaction. Vitamin D deficiency is highly prevalent in patients with alcoholic hepatitis. VitaminD supplementation regulates the expression of tight junction proteins, enhances antimicrobial defenses and reduces proinflammatory cytokines in the gut. Vitamin D targets osteopontin via a vitamin D-responsive element in the osteopontin promoter. Milk osteopontin protects the gut by maintaining the epithelial barrier function, providing mucosal defense, preventing sepsis and the inflammatory response. So far, a link between vitamin D and osteopontin in protecting from alcoholic hepatitis has not been established. We believe that nutritional therapy using vitamin D and milk osteopontin could protect from alcohol-induced liver injury. In this Application we will focus on testing the Central Hypothesis "Dietary supplementation with vitamin D or milk osteopontin could prevent alcoholic hepatitis due to the gut protective and antisteatotic actions of osteopontin". In particular, we hypothesize that vitamin D and milk osteopontin will: 1) Target the gut-liver axis protecting the intestinal mucosal barrier and blocking the translocation of Gram-negative bacteria from the gut into the portal circulation thus lowering lipopolysaccharide levels; 2) Prevent steatosis and liver injury by targeting fatty acid metabolism and decreasing lipopolysaccharide-mediated Kupffer cell activation and TNF¿ production; and 3) Avert hepatic steatosis, inflammation and liver injury by increasing autophagy, a recently identified pathway regulating steatosis. We will develop new in vivo models of alcoholic hepatitis to further our understanding of the mechanisms of liver injury. Using these models, mice will be treated with vitamin D or milk osteopontin to assess their therapeutic potential. To prove our hypothesis we plan three Specific Aims. In Aim 1, we will analyze if vitamin D and milk osteopontin block the ethanol-mediated increase in gut permeability, bacterial translocation and lipopolysaccharide availability. The chronic Lieber-DeCarli model along with dextran sodium sulfate treatment will be used. In Aim 2, first, we will determine whether vitamin D and milk osteopontin blunt steatosis by targeting fatty acid metabolism; and second, we will dissect if the ability of osteopontin to bind lipopolysaccharide lowers Kupffer cell activation, TNF¿ production as well as other pro-inflammatory cytokines. The chronic Lieber-DeCarli model along with dextran sodium sulfate or lipopolysaccharide treatment will be used. In Aim 3, a new model of alcoholic hepatitis based on autophagy blockade will be developed. Next, we will identify if vitamin D and milk osteopontin reduce steatosis by activating the autophagy pathway independent of targeting bacterial translocation or binding lipopolysaccharide. Thus, the Overall Goal of this Application is to investigate whether dietary administration of vitamin D and milk osteopontin could be an efficient low-cost therapeutic strategy for slowing down or preventing the progression of alcoholic hepatitis.