Background:A significant burden of atherosclerotic disease is driven by inflammation. Recently, microRNAs (miRNAs) have emerged as important factors driving and protecting from atherosclerosis. miR-223 regulates cholesterol metabolism and inflammation via targeting both cholesterol biosynthesis pathway and NF_kB signaling pathways; however, its role in atherosclerosis has not been investigated. We hypothesize that miR-223 globally regulates core inflammatory pathways in macrophages in response to inflammatory and atherogenic stimuli thus limiting the progression of atherosclerosis.Methods and Results:Loss of miR-223 in macrophages decreases Abca1 gene and protein expression as well as cholesterol efflux to apoA1 (Apolipoprotein A1) and enhances proinflammatory gene expression. In contrast, overexpression of miR-223 promotes the efflux of cholesterol and macrophage polarization toward an anti-inflammatory phenotype. These beneficial effects of miR-223 are dependent on its target gene, the transcription factor Sp3. Consistent with the antiatherogenic effects of miR-223 in vitro, mice receiving miR223^−/− bone marrow exhibit increased plaque size, lipid content, and circulating inflammatory cytokines (ie, IL-1β). Deficiency of miR-223 in bone marrow–derived cells also results in an increase in circulating pro-atherogenic cells (total monocytes and neutrophils) compared with control mice. Furthermore, the expression of miR-223 target gene (Sp3) and pro-inflammatory marker (Il-6) are enhanced whereas the expression of Abca1 and anti-inflammatory marker (Retnla) are reduced in aortic arches from mice lacking miR-223 in bone marrow–derived cells. In mice fed a high-cholesterol diet and in humans with unstable carotid atherosclerosis, the expression of miR-223 is increased. To further understand the molecular mechanisms underlying the effect of miR-223 on atherosclerosis in vivo, we characterized global RNA translation profile of macrophages isolated from mice receiving wild-type or miR223^−/− bone marrow. Using ribosome profiling, we reveal a notable upregulation of inflammatory signaling and lipid metabolism at the translation level but less significant at the transcription level. Analysis of upregulated genes at the translation level reveal an enrichment of miR-223-binding sites, confirming that miR-223 exerts significant changes in target genes in atherogenic macrophages via altering their translation.Conclusions:Our study demonstrates that miR-223 can protect against atherosclerosis by acting as a global regulator of RNA translation of cholesterol efflux and inflammation pathways.

中文翻译：

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miR-223 对巨噬细胞中的致动脉粥样硬化基因进行翻译控制

背景：动脉粥样硬化疾病的一个重大负担是由炎症驱动的。最近，microRNAs (miRNAs) 已成为驱动和保护动脉粥样硬化的重要因素。_{miR-223 通过靶向胆固醇生物合成途径和 NF k} B 信号通路调节胆固醇代谢和炎症；然而，尚未研究其在动脉粥样硬化中的作用。我们假设 miR-223 全局调节巨噬细胞中的核心炎症通路，以响应炎症和动脉粥样硬化刺激，从而限制动脉粥样硬化的进展。方法和结果：巨噬细胞中 miR-223 的损失降低Abca1基因和蛋白质表达以及胆固醇流出至 apoA1（载脂蛋白 A1）并增强促炎基因表达。相比之下，miR-223 的过表达促进胆固醇和巨噬细胞极化向抗炎表型的流出。miR-223 的这些有益作用取决于其靶基因转录因子Sp3。与 miR-223 在体外的抗动脉粥样硬化作用一致，接受miR223的小鼠^-/-骨髓表现出增加的斑块大小、脂质含量和循环炎性细胞因子（即 IL-1β）。与对照小鼠相比，骨髓衍生细胞中 miR-223 的缺乏也会导致循环的促动脉粥样硬化细胞（总单核细胞和中性粒细胞）增加。此外，miR-223靶基因（Sp3）和促炎标志物（Il-6）的表达增强，而Abca1和抗炎标志物（Retnla) 在骨髓衍生细胞中缺乏 miR-223 的小鼠的主动脉弓中减少。在喂食高胆固醇饮食的小鼠和患有不稳定颈动脉粥样硬化的人类中，miR-223 的表达增加。为了进一步了解 miR-223 对体内动脉粥样硬化影响的分子机制，我们表征了从接受野生型或miR223的小鼠中分离的巨噬细胞的全局 RNA 翻译谱^-/-骨髓。使用核糖体分析，我们揭示了在翻译水平上炎症信号和脂质代谢的显着上调，但在转录水平上则不那么显着。在翻译水平上对上调基因的分析揭示了 miR-223 结合位点的富集，证实 miR-223 通过改变其翻译对致动脉粥样硬化巨噬细胞中的靶基因产生显着变化。结论：我们的研究表明 miR-223 可以防止通过充当胆固醇流出和炎症通路的 RNA 翻译的全球调节剂，可预防动脉粥样硬化。