Development of Rac-Targeted Therapeutic Strategy for Treatment of Calcific Atherosclerosis

项目总结/摘要： 由钙化性动脉粥样硬化引起的冠状动脉疾病（CAD）是发病率和死亡率的单一主要原因。 全世界的死亡率。动脉粥样硬化斑块的钙成分对动脉粥样硬化的发生有预测价值。 心血管事件。炎症可能是血管钙化的关键介质，但免疫信号 对促进这一进程的机制知之甚少。最近，小型GTcycle，Rac 2， 被鉴定为指导斑块成骨的信号传导的主要炎症调节剂。粥样硬化 来自ApoE-/-小鼠的ApoE-/-小鼠在高脂饮食补充胆固醇的情况下， Rac 2 mRNA的表达。此外，Rac 2表达的降低与Rac 2表达的增加相关。 实验动物模型和人冠状动脉粥样硬化钙化 斑块Rac 2-/-ApoE -/-小鼠有助于确定Rac 2的保护作用，它阻止了进行性的 通过抑制Rac 1依赖性巨噬细胞IL-1β表达抑制钙化。菌斑和血清 结果显示，钙化斑块小鼠的IL-1β表达增加，此外， IL-1受体拮抗剂可抑制动脉粥样硬化钙化的增强。IL-1β的表达是一个关键的驱动因素 血管平滑肌细胞钙沉积的能力，促进成骨转录程序， 包括成骨转录因子RUNX 2、SOX 9、OSX和MSX 2的表达。骨髓 移植证实了可归因于Rac 2基因缺失的斑块进行性钙化， 取决于造血区室。几个关键问题仍然存在：1） 在标准实验模型中的斑块发展和动脉粥样硬化钙化中的巨噬细胞Rac 1; 2） 巨噬细胞是斑块IL-1β的关键细胞来源吗？3）Rac 2如何抑制Rac 1依赖性 巨噬细胞IL-1β表达;以及4）这些信号传导机制是否与钙化的动脉粥样硬化相关 冠状动脉疾病患者的斑块拟议研究的总体目标是 彻底回答这些问题。初步数据表明，Rac 1可以是一个关键启动子， Rac 2和Rac 1可能通过竞争IL-1β表达而相互拮抗。 类似于鸟嘌呤核苷酸交换因子Tiam 1，在激活IL-1β的条件下上调 表情假设巨噬细胞Rac信号决定动脉粥样硬化斑块IL-1β 表达和随后的炎性动脉粥样硬化钙化，从而破坏这一途径， 预防和治疗CAD的有效策略。Aim 1将定义巨噬细胞Rac 1在 斑块IL-1β表达和动脉粥样硬化钙化。Aim 2将确认Rac 1和Rac 2竞争 Tiam 1是一种关键的Rac-GEf，在巨噬细胞炎症激活期间以及 实验性动脉粥样硬化，IL-1β表达和炎性动脉粥样硬化钙化是 依赖于Tiam 1的表达。最后，Aim 3将证实这些巨噬细胞信号传导的有效性。 已知冠状动脉疾病患者动脉粥样硬化斑块样本中的机制。确认 巨噬细胞Rac-IL-1β信号轴是炎症性动脉粥样硬化的中心机制 钙化为开发治疗冠状动脉疾病的新治疗策略铺平了道路， 已经开发了Rac 1和Rac 1-Tiam 1相互作用的小分子抑制剂， 一些建议的研究。

PROJECT SUMMARY/ABSTRACT: Coronary artery disease (CAD) from calcific atherosclerosis is the single leading cause of morbidity and mortality worldwide. The calcium composition of atherosclerotic plaque has predictive value in terms of cardiovascular events. Inflammation is likely a key mediator of vascular calcification, but immune signaling mechanisms that promote this process are minimally understood. Recently, the small GTPase, Rac2, was identified as a major inflammatory regulator of signaling that directs plaque osteogenesis. Atherosclerotic aortas from ApoE-/- mice fed a high fat diet supplemented with cholesterol demonstrated dynamic expression of Rac2 mRNA expression over time. Moreover, decreased Rac2 expression correlated with increased atherosclerotic calcification, both in the experimental animal model and in human coronary artery plaques. Rac2 -/-ApoE -/- mice helped to define a protective role of Rac2, which prevented progressive calcification through its suppression of Rac1-dependent macrophage IL-1β expression. Plaque and serum from mice with calcified plaque demonstrated increased expression of IL-1β, and moreover, treatment with the IL-1 receptor antagonist inhibited the enhanced atherosclerotic calcification. IL-1β expression was a key driver of vascular smooth muscle cell calcium deposition by its ability to promote osteogenic transcriptional programs, including expression of the osteogenic transcription factors, RUNX2, SOX9, OSX and MSX2. Bone marrow transplantation confirmed the progressive calcification of plaque attributable to Rac2 gene deletion was dependent on the hematopoietic compartment. Several key questions remain: 1) what is the role of macrophage Rac1 in plaque development and atherosclerotic calcification in standard experimental models; 2) are macrophages the key cellular source of plaque IL-1β; 3) how does Rac2 suppress Rac1-dependent macrophage IL-1β expression; and 4) are these signaling mechanisms relevant to calcified atherosclerotic plaque from patients with coronary artery disease? The overall objective of the proposed studies is to thoroughly answer these questions. Preliminary data demonstrate that Rac1 can be a key promoter of macrophage IL-1β expression and that Rac2 and Rac1 may antagonize each other through competition for a similar guanine nucleotide exchange factor, Tiam1, which is upregulated under conditions that activate IL-1β expression. The hypothesis is that macrophage Rac signaling determines atherosclerotic plaque IL-1β expression and consequent inflammatory atherosclerotic calcification, and thus disrupting this pathway can be an effective strategy for the prevention and treatment of CAD. Aim1 will define the role of macrophage Rac1 in plaque IL-1β expression and atherosclerotic calcification. Aim2 will confirm that Rac1 and Rac2 compete for Tiam1, a critical Rac-GEf that is upregulated during macrophage inflammatory activation as well as during experimental atherosclerosis, and that IL-1β expression and inflammatory atherosclerotic calcification are dependent on Tiam1 expression. Finally, Aim3 will confirm the validity of these macrophage signaling mechanisms in atherosclerotic plaque samples from patients with known coronary artery disease. Confirming that a macrophage Rac-IL-1β signaling axis is a central mechanism in inflammatory atherosclerotic calcification paves the way for developing a novel therapeutic strategy for treating coronary artery disease, as small molecular inhibitors of Rac1 and Rac1-Tiam1 interactions have been developed and are incorporated into a number of the proposed studies.