Oxidized Low-Density Lipoprotein Immune Complexes Stimulate Proinflammatory Changes in Innate and Adaptive Immunity

项目摘要 心血管疾病（CVD）影响了近三分之一的美国人口，并导致了 每年约有100万美国人死亡。动脉粥样硬化，最常见的CVD形式， 是一种无菌性炎症疾病，其特征是动脉中斑块的积累。这是 被认为是由低密度脂蛋白（LDL）进入血管系统并被隔离而引发的 在那里它被氧化（oxLDL）。研究表明，循环中的大部分oxLDL必然会 特异性抗体形成oxLDL免疫复合物（oxLDL-ICs），且呈正相关 循环oxLDL-IC滴度与动脉粥样硬化疾病严重程度之间的关系。我们的研究表明， oxLDL-IC通过Fc γ受体（Fc γ R）、Toll样受体4和CD 36协同信号传导 小鼠骨髓来源的树突状细胞（BMDC）在体外，以提高生产 促动脉粥样硬化细胞因子IL-1 β。初步数据表明oxLDL-IC预处理的BMDC增强Th 17 和抑制Th 1应答。然而，这些差异性T细胞 反应似乎是一个单独的机制的结果。oxLDL-IC在体内的作用并不完全 理解，但我们的实验室已经表明，消除CD 11 c+细胞上的抑制性Fc γ R，Fc γ RIIb， 足以增加雌性Ldlr-/-小鼠的动脉粥样硬化。Fc受体表达于细胞表面， 抗原呈递细胞，如树突状细胞（DC）和巨噬细胞，以及激活性和抑制性Fc受体 分别引发相反的促炎和致耐受表型。由于oxLDL-IC正在发出信号 这些数据部分通过Fc受体提供了一种机制， DCs可促进动脉粥样硬化。此外，初步数据表明oxLDL-IC刺激 诱导BMDCs的代谢变化，而游离oxLDL则没有。oxLDL-IC激活的细胞更多 糖酵解，并增加备用呼吸能力。总的来说，这些数据导致 假设oxLDL-IC信号传导改变DC功能，导致T细胞活化的变化， 分化是促动脉粥样硬化的。本提案的目的1将确定oxLDL-IC刺激 DCs通过利用BMDC/T细胞共培养物与基因改变下游CD 4 + T细胞应答 敲除和阻断抗体、过继转移和体内oxLDL-IC注射。目标2将 研究oxLDL-IC诱导的代谢变化如何促进DC活化和功能 使用代谢通量实验、RNA测序和BMDC/T细胞共培养物与代谢通量实验， 抑制剂和基因敲除。总体而言，本提案将定义oxLDL-IC如何直接影响DC 功能以及随后如何影响CD 4 + T细胞。这些研究的成功将为 oxLDL-IC如何促进无菌性炎症并将拓宽我们对动脉粥样硬化的理解 和其它oxLDL-IC相关的自身炎性疾病。

PROJECT SUMMARY Cardiovascular disease (CVD) affects almost one third of the U.S. population and is responsible for the deaths of approximately 1 million Americans annually. Atherosclerosis, the most common form of CVD, is a disease of sterile inflammation characterized by the accumulation of plaque in the arteries. This is thought to be initiated by the entry and sequestration of low-density lipoprotein (LDL) in the vasculature where it becomes oxidized (oxLDL). Studies show that much of the oxLDL in circulation is bound to specific antibody to form oxLDL immune complexes (oxLDL-ICs) and there is a positive correlation between titers of circulating oxLDL-ICs and atherosclerosis disease severity. Our group has shown that oxLDL-ICs cooperatively signal through Fc gamma receptors (FcRs), Toll-like Receptor 4, and CD36 in murine bone marrow-derived dendritic cells (BMDCs) in vitro to enhance the production of proatherogenic cytokine IL-1. Preliminary data indicate oxLDL-IC pretreated BMDCs enhance Th17 and suppress Th1 responses, relative to oxLDL pretreated BMDCs. However, these differential T cell responses appear to be the result of a separate mechanisms. The role of oxLDL-ICs in vivo is not fully understood, but our lab has shown that elimination of the inhibitory FcR, FcRIIb, on CD11c+ cells is sufficient to increase atherosclerosis in female Ldlr-/- mice. FcRs are expressed on the surface of antigen presenting cells like dendritic cells (DCs) and macrophages, and activating and inhibitory FcRs elicit opposing pro-inflammatory and tolerogenic phenotypes, respectively. As oxLDL-ICs are signaling in part through FcRs, these data provide a mechanism by which oxLDL-IC signaling specifically on DCs could promote atherosclerosis. Furthermore, preliminary data demonstrate oxLDL-IC stimulation induces metabolic changes in BMDCs not seen with free oxLDL. Cells activated by oxLDL-IC are more glycolytic and have an increased spare respiratory capacity. Collectively, these data lead to the hypothesis oxLDL-IC signaling alters DC function resulting in changes in T cell activation and differentiation that are proatherogenic. Aim 1 of this proposal will determine how oxLDL-IC stimulation of DCs alters downstream CD4+ T cell responses by leveraging BMDC/T cell co-cultures with gene knockouts and blocking antibodies, adoptive transfers, and in vivo oxLDL-IC injections. Aim 2 will investigate how oxLDL-IC induced changes in metabolism contribute to DC activation and function using metabolic flux experiments, RNA sequencing, and BMDC/T cell co-cultures with metabolic inhibitors and gene knockouts. Overall, this proposal will define how oxLDL-ICs directly impact DC function and how CD4+ T cells are subsequently influenced. The success of these studies will inform how oxLDL-ICs contribute to sterile inflammation and will broaden our understanding of atherosclerosis and other oxLDL-IC associated autoinflammatory disorders.