Monocyte microRNA155 and atherosclerosis

描述(申请人提供)：动脉粥样硬化是由脂质沉积和慢性血管炎症引起的，其中单核/巨噬细胞起关键作用。最近发现的循环单核细胞和皮损巨噬细胞的异质性为单核/巨噬细胞参与动脉粥样硬化的机制提供了新的见解。一个新的概念是，在全身性促动脉粥样硬化应激(即高脂血症和炎症)的存在下，一些循环中的单核细胞获得独特的促炎表型，使它们能够渗透到动脉壁并在斑块内产生促炎的巨噬细胞亚群。MicroRNAs(MiRs)是一种短小的非编码RNA分子，能够通过靶向mRNAs来调节基因的表达，导致翻译抑制或mRNA降解。它们在多种生物和病理过程中发挥着重要作用，因此成为诊断和治疗多种人类疾病的新靶点。一个miR，miR155，已被证明在免疫反应调节中发挥关键作用。最近的研究表明，在Toll样受体的不同配体刺激下，miR155在单核细胞和巨噬细胞中的表达上调，它可能通过靶向TLR介导的信号转导的几个负调控因子而加剧单核细胞和巨噬细胞的炎症反应。虽然TLRs及其配体基本上参与了动脉粥样硬化的形成，但单核/巨噬细胞miR155在动脉粥样硬化中的作用尚未被研究。我们的初步研究表明，单核/巨噬细胞miR155在动脉粥样硬化中具有潜在的作用，并促使我们假设miR155表达上调是循环单核细胞促动脉粥样硬化表型的一个完整特征。为了检验这一假说，本文提出了两个具体目标。SA1.验证动脉粥样硬化小鼠外周血单核细胞miR155表达上调的假设。我们将使用两种高胆固醇血症小鼠模型测量miR155在循环单核细胞中的表达，评估其与病变大小、血脂和炎症标志物的相关性，并检查miR155是否在循环单核细胞亚群中差异表达。SA2.为了验证miR155表达增加代表单核细胞促动脉粥样硬化表型的假设。我们用慢病毒载体转导小鼠单核细胞，将miR155过表达或抑制，并检测miR155操作对单核细胞与主动脉内皮细胞黏附、内膜浸润和泡沫细胞转化的影响。我们还将探索潜在的分子机制。 公共卫生相关性：动脉粥样硬化是心脏病发作和中风的直接原因，在美国，这两种疾病是头号和第三大杀手。迫切需要更灵敏的非侵入性诊断工具来检测临床事件的高危患者，并开发有效和安全的抗炎疗法来补充动脉粥样硬化的降胆固醇治疗。将miR155确定为循环单核细胞促动脉粥样硬化的特征有可能显著影响未来的临床实践。

DESCRIPTION (provided by applicant): Atherosclerosis is evoked by both lipid deposition and chronic vascular inflammation, in which monocytes/macrophages play critical roles. The recent identification of heterogeneity of circulating monocytes and lesional macrophages has provided new insights into the mechanism underlying the involvement of monocytes/macrophages in atherogenesis. An emerging notion is that in the presence of systemic pro-atherogenic stress (i.e., hyperlipidemia and inflammation), some circulating monocytes acquire distinct pro-inflammatory phenotypes that prime them to infiltrate the arterial wall and give rise to a pro-inflammatory macrophage subset within the plaque. MicroRNAs (miRs) are short non-coding RNA molecules capable of regulating gene expression by targeting mRNAs, resulting in translational repression or mRNA degradation. They play essential roles in multiple biological and pathological processes, thus emerging as new targets for diagnosis and therapy of several human diseases. One miR, miR155, has been demonstrated to play a crucial role in immune response regulation. Recent studies have shown that miR155 expression in monocytes and macrophages is up-regulated upon stimulation with various ligands for toll-like receptors (TLRs), and it may exaggerate monocyte and macrophage inflammation by targeting several negative regulators of TLR-mediated signaling. While TLRs and their ligands are fundamentally involved in atherogenesis, the contribution of monocyte/macrophage miR155 to atherosclerosis has not been investigated. Our preliminary studies suggest a potential role of monocyte/macrophage miR155 in atherosclerosis, and prompt us to hypothesize that up-regulation of miR155 expression is an integral feature of the pro-atherogenic phenotype of circulating monocytes. Two specific aims are proposed to test this hypothesis. SA1. To test the hypothesis that miR155 expression is up-regulated in circulating monocytes of atherosclerotic mice. We will measure miR155 expression in circulating monocytes using two hypercholesterolemic mouse models, evaluate its correlation with lesion size, plasma lipids, and inflammatory markers, and examine whether miR155 is differentially expressed in circulating monocyte subsets. SA2. To test the hypothesis that increased miR155 expression represents a pro-atherogenic phenotype of monocytes. We will transduce monocytes isolated from mice with lentiviral vectors to introduce miR155 overexpression or inhibition, and test the effects of miR155 manipulation on monocyte adhesion to aortic endothelium, infiltration into intima and foam cell transformation. We will also explore the underlying molecular mechanism. PUBLIC HEALTH RELEVANCE: Atherosclerosis is the direct cause of heart attack and stroke, the No. 1 and No. 3 killers in the United States. There is an urgent call for more sensitive noninvasive diagnostic tools to detect patients at high risk of clinical events as well as for developing effective and safe anti-inflammation therapies to complement cholesterol-lowering therapy for atherosclerosis. The identification of miR155 as a pro- atherogenic feature of circulating monocytes holds the potential to significantly impact future clinical practice.