PPAR?? and Alveolar Macrophage Phenotype in Acute Lung Injury

描述（由申请人提供）：该职业发展奖的目的是提高对急性肺损伤（ALI）发病机制的理解，以促进新的有效治疗方法的开发。ALI是一种常见的致命性呼吸衰竭，每年有20万人发生，其中多达25%的机械通气患者发生。目前还没有有效的药物治疗ALI，死亡率保持在近40%。慢性共病改变了发生ALI的风险，糖尿病（DM）是唯一被证实可降低感染性休克患者ALI发生率的疾病。这一意想不到的观察结果是检查ALI发病机制的基础，以了解疾病修饰途径，以减轻这种病态急性疾病的风险。PPARg活性影响AM宿主的免疫功能，包括吞噬作用，我们的初步数据表明，PPARg活性，AM激活的关键调节因子，在其他健康的糖尿病患者中增加;并且AM功能在脓毒症中降低，脓毒症是ALI的最常见原因。在这种情况下，可以假设AM中的相对PPARg活化应该与糖尿病患者以及非糖尿病患者的ALI风险相关。因此，研究AM功能与ALI的关系具有重要意义。此外，PPARg活化代表了一种有吸引力的治疗靶点，其不仅可以降低糖尿病患者的急性肺损伤的发生率或严重程度，而且还可以降低患有脓毒症或其他急性应激的非糖尿病患者的急性肺损伤的发生率或严重程度。在此背景下，我们假设与健康对照组相比，健康糖尿病患者的AM PPARg活性增加，严重脓毒症患者AM PPARg活性和吞噬功能降低与ALI风险增加独立相关。此外，我们假设在体外用PPARg-配体处理AM将增加PPARg活性，从而增加替代活化（M2）抗炎表型的表达并改善吞噬作用。本研究的目的是：1）确定DM对肺泡巨噬细胞（AM）PPARg活性、表型和吞噬功能的影响; 2）确定AM PPAR 3活性、AM M2分化和吞噬功能对ALI发生的预测价值;和3）确定体外暴露于PPARg-配体对从对照、糖尿病和脓毒症患者分离的AM的表型和功能的影响。总体目标是确定糖尿病和ALI发病率降低之间的关联是否转化为PPARg活性增加和ALI风险降低之间的关联。为了验证我们的假设，我们将在其他方面健康的糖尿病患者、严重脓毒症受试者和健康对照者中进行研究。合格受试者将接受支气管肺泡灌洗的支气管镜检查，以分离AM，并进行测定PPARg活性、AM分化标志物（M1/M2标志物）和AM吞噬功能的试验。将重复这些研究，目的3测试AM暴露于PPARg配体并确定其对AM分化和吞噬功能的影响。这些研究将评估PPARg活性对ALI发展的影响，并确定PPARg在调节AM对肺部炎症反应中的作用。由于PPARg是肺中急性炎症反应的关键调节组分，并有效地抑制ALI动物模型中的炎症和损伤，因此我们必须研究该受体在人类肺部疾病中的发病机制和潜在治疗作用。拟议的研究将在一名具有开展临床研究专业知识的经验丰富的导师和一名具有开展基础研究专业知识的共同导师的指导下进行;由职业发展委员会和与多学科科学团队的合作进行补充。K23职业发展奖提供的支持将使我能够建立在我以前的研究所创建的基础上，并继续实现我成为独立临床研究者的目标，最终目标是成为ALI发病机制的专家。这将通过接受教学培训，通过完成MSCR计划和免疫学课程，与我的导师和一个完善的咨询委员会的互动，以及埃默里大学的环境来实现，所有这些都将进一步完善和发展我的调查和分析技能。K23计划提供的培训机会将为获得未来NIH资助提供直接途径，例如R 01奖项，这将使我能够成功地扩展我的研究重点，并扩大我们对ALI病理生理学的理解。

DESCRIPTION (provided by applicant): The objective of this Career Development Award is to enhance understanding of acute lung injury (ALI) pathogenesis in order to facilitate development of new effective therapies. ALI is a common and lethal form of respiratory failure, occurring in 200,000 people each year and in as many as 25% of mechanically ventilated patients. There are presently no effective medical therapies for ALI, and mortality remains at nearly 40%. Chronic co-morbid conditions alter the risk for developing ALI, and diabetes mellitus (DM) is the only identified condition shown to decrease the incidence of ALI in patients with septic shock. This unexpected observation serves as the foundation for examining ALI pathogenesis to understand disease-modifying pathways to mitigate the risk for such a morbid acute illness. PPARg activity influences AM host immune functions including phagocytosis, and our preliminary data suggest that PPARg activity, a key regulator of AM activation, is increased in otherwise healthy diabetics; and that AM function is decreased in sepsis, the most common cause of ALI. In this context, one could postulate that the relative PPARg activation in the AM should correlate with the risk of ALI in diabetics as well as in non-diabetics. Therefore, the association between AM function and ALI development is of importance to investigate. In addition, PPARg activation represents an attractive therapeutic target that could decrease the incidence or severity of acute lung injury not only in diabetics, but also in non-diabetics with sepsis or other acute stresses. With this background, we hypothesize that otherwise healthy diabetics will have increased AM PPARg activity when compared to healthy controls and that decreased AM PPARg activity and phagocytic function in severe sepsis are independently associated with increased risk of ALI. Furthermore, we hypothesize that treatment of AMs with a PPARg-ligand in vitro will increase PPARg activity, thereby increasing expression of the alternative activation (M2) anti-inflammatory phenotype and improving phagocytosis. Our hypothesis will be tested in Specific Aims designed to 1) determine the effect of DM on alveolar macrophage (AM) PPARg activity, phenotype and phagocytic function; 2) establish the predictive value of AM PPAR3 activity, AM M2 differentiation and phagocytic function for the development of ALI; and 3) determine the effect of PPARg-ligand exposure in vitro on the phenotype and function of AMs isolated from control, diabetic and septic patients. The overall objective is to determine if the association between diabetes and decreased incidence of ALI translates to an association between increase PPARg activity and decreased risk of ALI. To test our hypothesis, we will conduct studies in otherwise healthy diabetics, subjects with severe sepsis and healthy controls. Eligible subjects will undergo bronchoscopy with bronchoalveolar lavage to isolate AMs and perform assays measuring PPARg activity, markers of AM differentiation (M1/M2 markers) and AM phagocytic function. These studies will be repeated, in Aim 3 testing exposure of AMs to PPARg ligand and determining its effect on AM differentiation and phagocytic function. The proposed studies will evaluate the impact of PPARg activity on development of ALI and will determine the role of PPARg in regulating AMs response to pulmonary inflammation. Since PPARg is a key regulatory component of acute inflammatory responses in the lung, and effectively dampens inflammation and injury in animal models of ALI, it is imperative that we investigate the pathogenetic and potential therapeutic role of this receptor in human lung disease. The proposed studies will be carried out under the guidance of an experienced mentor who has expertise in conducting clinical research, and a co-mentor with expertise in conducting basic research; supplemented by a career development committee and collaborations with a multi-disciplinary scientific team. The support provided by the K23 Career Development Award will allow me to build upon the foundation I have created with my previous studies, and continue towards my goal of becoming an independent clinical investigator with the ultimate goal of becoming an expert in ALI pathogenesis. This will be accomplished by receiving didactic training through completion of the MSCR program and courses in immunology, interactions with my mentor and a well-established advisory committee, and the Emory environment, all of which will further refine and develop my investigational and analytical skills. The training opportunity provided by the K23 program will provide a direct path for obtaining future NIH funding, such R01 awards, which will allow me to successfully extend my research focus and broaden our understanding of the pathophysiology of ALI.