Role of ABCG1 in lipid homeostasis, inflammation and innate immunity

描述(由申请人提供)：本申请详细说明了一个为期五年的职业发展计划，以促进从有指导的博士后研究员向独立研究人员的转变。申请者已经完成了4.5年的博士后培训，其中1年在英国，3.5年在加州大学洛杉矶分校。申请者将继续接受彼得·爱德华兹博士的指导，他是胆固醇和脂肪代谢领域公认的领导者。彼得·通托诺兹博士是一位备受尊敬的科学家，在核受体、炎症和心血管疾病领域拥有专业知识，他将担任申请者的共同导师。重要的是，爱德华兹博士和汤托诺兹博士成功地培养了一批研究人员，他们已经成为独立的学术科学家。与肯尼斯·多什金德博士(加州大学洛杉矶分校)和乔·维茨图姆博士(加州大学洛杉矶分校)的持续积极互动，都是B-1B细胞和天然抗体(NAB)方面的专家，为应用程序的特定方面增加了特别的优势。炎症是动脉粥样硬化、自身免疫、肥胖和癌症等疾病的特征。炎症是先天(先天)免疫系统对病原体的典型反应。影响炎症的因素可以对疾病的进展产生深远的影响。例如，脂肪条纹的形成和随后发展为动脉粥样硬化病变与动脉壁内膜内胆固醇和胆固醇酯的积累有关。细胞内和细胞外脂质的这些变化导致了炎症反应，通常认为这种炎症反应对病变的发展具有有害影响。我特别感兴趣的是识别影响脂肪沉积、炎症和疾病的蛋白质，然后确定它们的作用机制。为此，我们已经证明：1)三磷酸腺苷结合盒转运体G1(Abcg1)调节细胞内的固醇运动，并促进细胞内胆固醇和氧合固醇向外源性脂质受体的运输；2)缺乏Abcg1的小鼠出现严重的肺脂血症和慢性炎症。出乎意料的是，Abcg1-/-小鼠表现出动脉粥样硬化的减轻，尽管促炎细胞因子水平增加，肺脂沉积增加。这项建议的主要目的是了解维持炎症反应的机制，以及Abcg1在脂质稳态、炎症和先天免疫中的作用。在特定的目标1中，我将测试Abcg1的细胞特异性缺失对炎症反应有显著影响的假设。我建议产生Abcg1缺陷的小鼠，特别是II型肺泡细胞(T2细胞；Abcg1T2-/T2-)。然后，我将研究Abcg1T2-/T2-MIE，以确定T2细胞Abcg1对肺表面活性物质代谢、肺脂稳态的特殊重要性，包括对影响先天性免疫和炎症的脂类抗原生成的影响。在具体目标2中，我将检验Abcg1基因缺失调节先天免疫、炎症和动脉粥样硬化进展的假说。使用过继转移研究和Rag2-/-Ldlr-/-高脂血症小鼠，然后我将确定缺乏Abcg1的不同B细胞亚型在动脉粥样硬化发展中的相对贡献，特别是B-1B细胞和分泌的NAB的动脉粥样硬化保护功能。在这项申请中提出的研究的长期目标之一是进一步了解介导炎症反应的因素以及它们如何转化为疾病预防，使用先天免疫系统和动脉粥样硬化作为模型系统。

DESCRIPTION (provided by applicant): This application details a five-year career development program to facilitate the transition from a mentored post-doctoral fellow to an independent researcher. The applicant has completed 4.5 years of post- doctoral training, 1 in the UK and 3.5 at the University of California, Los Angeles. The applicant will continue to be mentored by Dr Peter Edwards, a recognized leader in the field of cholesterol and lipid metabolism. Dr Peter Tontonoz, a highly respected scientist with expertise in the areas of nuclear receptors, inflammation and cardiovascular disease, will act as co-mentor to the applicant. Importantly, Drs Edwards and Tontonoz have successfully trained a number of investigators who have become independent academic scientists. Continued active interactions with Drs Kenneth Dorshkind (UCLA) and Joe Witztum (UCSD), both experts in B-1 B cells and natural antibodies (NAbs), adds particular strengths to specific aspects of the application. Inflammation is a hallmark characteristic of diseases such as atherosclerosis, autoimmunity, obesity and cancer. Inflammation is a stereotypical response of the innate (inborn) immune system to pathogens. Factors that influence inflammation can have a profound effect on disease progression. For example, the formation of fatty streaks and subsequent progression to atherosclerotic lesions is associated with accumulation of cholesterol and cholesterol esters within the intima of the artery wall. These changes in intracellular and extracellular lipids resul in an inflammatory response that is generally thought to have deleterious effects on lesion development. I am particularly interested in identifying proteins that affect lipid deposition, inflammation and disease, and then defining their mechanism of action. To this end, we have shown that i) the ATP Binding Cassette Transporter G1 (ABCG1) modulates both intracellular sterol movement and facilitates the transport of cellular cholesterol and oxysterols to exogenous lipid acceptors and ii) mice lacking ABCG1 develop severe pulmonary lipidosis and chronic inflammation. Unexpectedly, Abcg1-/- mice exhibit reduced atherosclerosis, despite enhanced levels of pro-inflammatory cytokines and increased pulmonary lipid deposition. The primary aim of this proposal is to understand the mechanisms involved in maintaining inflammatory responses and the role of ABCG1 in lipid homeostasis, inflammation, and innate immunity. In Specific Aim 1 I will test the hypothesis that cell-specific deletion of ABCG1 has significant consequences for inflammatory responses. I propose to generate mice deficient in ABCG1 specifically in type II pneumocytes (T2 cells; Abcg1T2-/T2-). I will then study the Abcg1T2-/T2- mie to determine the specific importance of T2 cell ABCG1 on surfactant metabolism, lung lipid homeostasis, including the effect on the generation of lipid antigens that affect innate immunity and inflammation. In Specific Aim 2 I will test the hypothesis that loss of ABCG1 modulates innate immunity, inflammation and atherosclerosis progression. Using adoptive transfer studies and Rag2-/-Ldlr-/- hyperlipidemic mice, I will then determine the relative contribution of differen B cell subtypes that lack ABCG1 on the development of atherosclerosis, focusing particularly on the athero- protective function of B-1 B cells and secreted NAbs. One of the long term goals of the studies put forward in this application is to further understand factors that mediate inflammatory responses and how they translate to disease prevention, using the innate immune system and atherosclerosis as model systems.