Mechanisms for Arsenic-Induced Vascular Disease

描述(由申请人提供)：为回应NOT-OD-09-058：美国国立卫生研究院宣布恢复法可用于竞争性修订申请；这是一项竞争性修订申请，以扩大5R01-ES013781-02的AIMS的范围：砷诱导的血管疾病的机制。众所周知，长期接触三价砷会导致心血管疾病。在人类肝脏中，砷促进血管重塑、门脉纤维化和高血压，但这些由砷引起的血管改变的分子病理生理机制尚不清楚。最近，接触砷与新陈代谢和心血管疾病有关。我们在5R01-ES013781-02中提出，砷对高度特化的肝窦内皮细胞(LSEC)的作用参与了砷暴露的心血管发病机制。AIMS 5R01-ES013781-02研究了一种假设，即砷在G蛋白偶联细胞信号水平上作用于增加NADPH氧化剂的生成，从而扰乱肝脏肝窦LSEC窗口的维持和抑制毛细血管形成，这一过程限制了脂质代谢和蛋白质清除功能。这些研究的具体目标没有改变，目的是确定：i.砷引起完整小鼠肝窦毛细血管形成和重塑的分子机制；ii.基于NOX2的NADPH氧化酶产生的超氧化物在介导砷诱导的原代小鼠和人LSEC表型转换中的作用；以及III.LSEC GTP酶活性失衡是否介导了砷刺激的LSEC重塑。这些研究仅限于调查体内暴露的头两周内砷反应的启动情况。在拨款的第一年发表的研究为最初的目标2提供了假说的证据，证明了砷未能重塑和毛细管缺乏NADPH氧化酶的小鼠的肝脏血管系统。其他探索性研究表明，长期暴露于饮用水中与环境相关的砷水平会导致结肠细菌基因类型的渐进性变化。这次修订提出了两个新的目标，将这些发现转化为调查以下假设：砷刺激的LSEC功能障碍和肠道微生物组的转换会导致清除活性的病理性丧失、腹部脂肪中不适当的脂肪沉积，以及肝脏和心脏的微血管重构。其目的是调查：1.调查环境暴露引起的LSEC毛细血管形成和功能障碍降低LSEC清除活性，增加脂肪沉积，并重塑心脏微血管的假说；2.调查砷暴露对胃肠道细菌群落结构和定殖谱的影响，以及LSEC表型和系统变化对肠道微生物群的作用。这些研究将提供基础研究5R01-ES013781-02与疾病预后的重要联系，并极大地加速确定LSEC功能障碍和肠道微生物群变化在环境源性代谢和血管疾病病因学中的作用。 公共卫生相关性：众所周知，砷会导致全球数百万人患上心血管和代谢相关疾病；然而，人们对慢性低水平砷暴露的健康风险机制知之甚少。这些研究将使用与人类相关的环境中暴露的完整小鼠以及小鼠和人类细胞的初级分离株来揭示砷诱导的肝脏和全身血管床血管重塑背后的分子病理学，以确定一种新的作用模式，通过这种新的作用模式，低水平的慢性砷暴露促进血管疾病。此外，这些研究还将研究砷对胃肠道细菌菌落的影响如何影响宿主新陈代谢，从而影响疾病进展。

DESCRIPTION (provided by applicant): In response to NOT-OD-09-058: NIH Announces the Availability of Recovery Act for Competitive Revision Applications; this is an application for a competitive revision to expand the scope of the aims for 5R01- ES013781-02: Mechanisms for arsenic-induced vascular disease. Chronic exposure to trivalent arsenic is well known to cause cardiovascular diseases. In the human liver, arsenic promotes vascular remodeling, portal fibrosis, and hypertension, but the molecular pathophysiology of these arsenic-induced vascular changes is unknown. More recently, arsenic exposures have been linked to metabolic, as well as cardiovascular diseases. We proposed in 5R01-ES013781-02 that arsenic effects on the highly specialized liver sinusoidal endothelial cells (LSEC) contribute to the cardiovascular pathogenesis of arsenic exposures. The aims 5R01-ES013781- 02 investigate the hypothesis that arsenic acts at the level of G-protein coupled cell signaling to increase NADPH oxidase oxidant generation that disrupts maintenance of liver sinusoidal LSEC fenestrations and suppression of capillarization, a process that limits lipid metabolism and protein scavenging functions. The Specific Aims have not changed and are to determine: I. the molecular mechanism by which arsenic causes liver sinusoidal capillarization and remodeling in intact mice; II. the role of Nox2-based NADPH oxidase generated superoxide in mediating arsenic -induced phenotypic conversion of primary murine and human LSEC; and III. if an imbalance in LSEC GTPase activity mediates arsenic-stimulated remodeling of the LSEC. These studies were limited to investigating the initiation of arsenic responses within the first two weeks of in vivo exposure. Studies published in the first year of the grant provided proof of hypothesis for original aim 2 by demonstrating that arsenic failed to remodel and capilliarize the liver vasculature in mice lacking NADPH oxidase. Additional exploratory studies demonstrated that prolonged exposure to environmentally relevant levels of arsenic in drinking water caused progressive change in the genotypes of bacteria in the colon. This revision proposes two new aims that will translate these findings to investigating the hypothesis that arsenic-stimulated LSEC dysfunction and conversion of the gut microbiome result in pathogenic loss of scavenging activity, inappropriate lipid deposition in abdominal fat, and microvessel remodeling in the liver and heart. The aims will investigate: I. investigate the hypothesis that LSEC capillarization and dysfunction caused by environmental exposure to arsenic decreases LSEC scavenging activity, increases fat deposition, and remodels cardiac microvessels; and II. investigate the impact of arsenic exposure on the gastrointestinal tract bacterial community structure and colonization profile and the role of LSEC phenotype and systemic changes on the gut microbiome. These studies will provide essential connection of the basic studies 5R01-ES013781- 02 with disease outcomes and greatly accelerate identifying the role of LSEC dysfunction and gut microbiome changes in the etiology of environmentally-derived metabolic and vascular diseases. PUBLIC HEALTH RELEVANCE: It is known that arsenic causes cardiovascular and metabolic-linked diseases in millions of people worldwide; however, the mechanisms for the health risks of chronic low level arsenic exposures are poorly understood. These studies will use human-relevant environmental arsenic exposures of intact mice and primary isolates of mouse and human cells to reveal the molecular pathology underlying arsenic-induced vascular remodeling in the liver and systemic vascular beds to define a novel mode of action through which low, chronic arsenic exposures promote vascular diseases. In addition, these studies will examine how arsenic effects on the bacterial colonies in the gastrointestinal tract influence host metabolism to influence disease progression.