Novel Effects of Gravity on Intestinal Epithelial Barrier Responses to Alcohol

描述（由申请人提供）：酒精给药增加胃肠道对细菌和细菌内毒素（脂多糖（LPS））的通透性，这在酒精诱导的组织/器官损伤，特别是酒精性肝病（ALD）的开始中起主要作用。通透性增加似乎主要是通过毒性代谢物乙醛对上皮间紧密连接（TJ）的作用而发生的，而上皮间紧密连接是肠屏障的主要组成部分。因此，了解酒精促进肠上皮细胞（IEC）通透性的潜在机制对于设计预防或治疗酒精相关疾病的策略非常重要。在人体中，细胞通常在蛋白质和碳水化合物纤维的支架中生长，这有助于形成三维结构，从而使器官保持其形状。当研究地球上的细胞和体外的细胞时，困难出现了，细胞往往生长在扁平的薄片上，不能复制它们通常拥有的结构。因此，三维微重力环境可能代表了更准确的上皮细胞在体内行为的细胞培养模型。此外，在国际空间站上缺乏对上皮细胞屏障功能的基本物理引力，这为研究重力对细胞特性的影响提供了一个独特的机会。我们假设微重力对肠上皮细胞屏障特性的影响显著改变了酒精对上皮屏障功能的影响。我们将在UH2期通过(i)量化模拟微重力对肠上皮细胞紧密连接蛋白和上皮通透性的影响来验证这一假设；㈡在模拟微重力条件下测试酒精对IEC阻隔性能的影响；（iii）优化三维细胞培养系统，以研究国际空间站上的屏障功能。在UH3阶段，我们将（四）量化微重力对国际空间站上酒精引起的IEC渗透性的影响。这些研究将提供一个明确的答案，上皮屏障功能在多大程度上受到重力的影响，以及这如何影响上皮对摄入毒素的反应。因此，我们将提供可能对人类健康产生重大积极影响的新的基础知识，并允许合理开发与饮酒和肠道屏障功能缺陷相关的疾病的新治疗策略。

DESCRIPTION (provided by applicant): Alcohol administration increases gastrointestinal permeability to bacteria and bacterial endotoxin (lipopolysaccharide (LPS)), and this plays a major role in the initiation of alcohol-induced tissue/organ damage in particular, alcoholic liver disease (ALD). Increased permeability appears to occur principally though the action of the toxic metabolite, acetaldehyde, on interepithelial tight junctions (TJ) that form a major component of the intestinal barrier. Therefore, understanding the underlying mechanisms by which alcohol promotes intestinal epithelial cell (IEC) permeability is important in designing strategies for the prevention or treatment of alcohol-associated medical disorders. In the human body, cells normally grow within a scaffolding of protein and carbohydrate fibers that help create a three dimensional (3-D) structure, thus allowing organs maintain their shape. Difficulties arise when studying cells on Earth as outside of the body, cells tend to grow in flat sheets and are not capable of duplicating the structure they normally hold. Therefore, a 3-D microgravity environment likely represents a more accurate cell culture model of epithelial behavior in vivo. Furthermore, the absence of the fundamental physical force of gravity on epithelial cell barrier function on board the ISS lends a unique opportunity to study the influence of gravity on cellular properties. We hypothesize that the influence of microgravity on the barrier properties of intestinal epithelial cells significantly modifies alcohol-induced effects on epithelial barrier function. We will test this hypothesis in the UH2 phase by (i) quantifying the effects of simulated microgravity on intestinal epithelial cell tight junction proteins and epithelial permeability; (ii) testing the effects of alcohol on barrier properties of IEC under simulated microgravity; (iii) optimizing a 3-dimensional cell culture system to study barrier function on board the ISS. In the UH3 phase we will (iv) quantify the effects of microgravity on IEC permeability induced by alcohol on board the ISS. These studies will provide a definitive answer as to what extent epithelial barrier function is influenced by gravity, and how this impacts upon epithelial responses to ingested toxins. As a result, we will provide new and fundamental knowledge that will likely have significant positive effects on human health, and allow the rational development of new therapeutic strategies for diseases associated with alcohol consumption and deficient intestinal barrier function. PUBLIC HEALTH RELEVANCE: From 2001-2005, there were approximately 79,000 deaths annually attributable to excessive alcohol use, the 3rd leading lifestyle-related cause of death for people in the U.S. each year (Centers for Disease Control). A major contributor to alcohol-induced disease is the ability of alcohol to compromise the normal barrier function of intestinal epithelial cells that line the gut. This project will utilize the unique zero- gravity environment of the International Space Station (ISS) to generate novel fundamental insights into the role of gravity in regulating intestinal barrier properties, and how the absence of gravity modifies the detrimental influence of alcohol on intestinal epithelial cell barrier function.