Monocyte microRNA155 and atherosclerosis

描述（由申请方提供）：脂质沉积和慢性血管炎症均诱发动脉粥样硬化，其中单核细胞/巨噬细胞发挥关键作用。最近对循环单核细胞和病变巨噬细胞异质性的鉴定为单核细胞/巨噬细胞参与动脉粥样硬化形成的机制提供了新的见解。一个新兴的概念是，在存在全身促动脉粥样硬化应激（即，高脂血症和炎症），一些循环单核细胞获得不同的促炎表型，使它们渗透动脉壁并在斑块内产生促炎巨噬细胞亚群。microRNA（miRs）是一种短的非编码RNA分子，能够通过靶向mRNA调节基因表达，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重要作用，因此成为诊断和治疗多种人类疾病的新靶点。miR 155是一种在免疫应答调控中发挥重要作用的miR。最近的研究表明，单核细胞和巨噬细胞中的miR 155表达在用toll样受体（TLR）的各种配体刺激后上调，并且它可能通过靶向TLR介导的信号传导的几种负调节剂而加重单核细胞和巨噬细胞炎症。尽管TLR及其配体基本上参与动脉粥样硬化形成，但尚未研究单核细胞/巨噬细胞miR 155对动脉粥样硬化的贡献。我们的初步研究表明单核细胞/巨噬细胞miR 155在动脉粥样硬化中的潜在作用，并提示我们假设miR 155表达的上调是循环单核细胞促动脉粥样硬化表型的一个组成部分。提出了两个具体目标来检验这一假设。SA 1.验证动脉粥样硬化小鼠循环单核细胞中miR 155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循环单核细胞中miR 155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miR 155是否在循环单核细胞亚群中差异表达。SA 2.检验miR 155表达增加代表单核细胞促动脉粥样硬化表型的假设。我们将用慢病毒载体转染从小鼠分离的单核细胞，以引入miR 155过表达或抑制，并测试miR 155操作对单核细胞粘附于主动脉内皮、浸润到内膜和泡沫细胞转化的影响。我们还将探讨潜在的分子机制。 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，是美国第一和第三大杀手。迫切需要更灵敏的非侵入性诊断工具来检测临床事件高风险患者，以及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疗法。将miR 155鉴定为循环单核细胞的促动脉粥样硬化特征具有显著影响未来临床实践的潜力。

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.