Role of ABCG1 in lipid homeostasis, inflammation and innate immunity

描述（由申请人提供）：这份申请详细说明了一个五年的职业发展计划，以促进从指导博士后到独立研究员的过渡。申请人已完成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。申请人将继续接受Peter Edwards博士的指导，他是胆固醇和脂质代谢领域公认的领导者。Peter Tontonoz博士是一位在核受体、炎症和心血管疾病领域具有专业知识的备受尊敬的科学家，他将担任申请人的共同导师。重要的是，Edwards博士和Tontonoz博士成功地培养了一批已经成为独立学术科学家的研究人员。与B- 1b B细胞和天然抗体（nab）方面的专家Kenneth Dorshkind博士（UCLA）和Joe Witztum博士（UCSD）的持续积极互动，为该应用的特定方面增添了特别的优势。炎症是动脉粥样硬化、自身免疫、肥胖和癌症等疾病的标志性特征。炎症是先天免疫系统对病原体的一种典型反应。影响炎症的因素对疾病进展有深远的影响。例如，脂肪条纹的形成和随后的动脉粥样硬化病变进展与动脉壁内膜内胆固醇和胆固醇酯的积累有关。这些细胞内和细胞外脂质的变化导致炎症反应，通常被认为对病变发展有有害影响。我特别感兴趣的是识别影响脂质沉积、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，i) ATP结合盒转运体G1 （ABCG1）调节细胞内固醇运动，促进细胞胆固醇和氧甾醇向外源性脂质受体的运输，ii)缺乏ABCG1的小鼠会发生严重的肺脂质病和慢性炎症。出乎意料的是，尽管促炎细胞因子水平升高，肺脂质沉积增加，但Abcg1-/-小鼠表现出动脉粥样硬化减少。本研究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Specific Aim 1中，我将检验细胞特异性缺失ABCG1对炎症反应有显著影响的假设。我建议在II型肺细胞（T2细胞；Abcg1T2-/T2-）中特异性地产生ABCG1缺失的小鼠。然后，我将研究Abcg1T2-/T2- mie，以确定T2细胞ABCG1对表面活性剂代谢、肺脂质稳态的特定重要性，包括对影响先天免疫和炎症的脂质抗原产生的影响。在Specific Aim 2中，我将验证ABCG1缺失调节先天免疫、炎症和动脉粥样硬化进展的假设。通过过继转移研究和Rag2-/- ldlr -/-高脂血症小鼠，我将确定缺乏ABCG1的不同B细胞亚型对动脉粥样硬化发展的相对贡献，特别关注B-1 B细胞和分泌的nab的动脉粥样硬化保护功能。本研究的长期目标之一是进一步了解介导炎症反应的因素及其如何转化为疾病预防，以先天免疫系统和动脉粥样硬化为模型系统。

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.