Conjugated linoleic acid nitration in vascular inflammation and atherosclerosis

 描述（由申请人提供）：靶向血管炎症和适应性免疫应答正在成为降脂治疗以外的新策略，以减轻动脉粥样硬化的负担，动脉粥样硬化是美国心血管疾病死亡的主要原因。在其他脂肪酸种类中，一氧化氮依赖性脂肪酸硝化产物（硝基烯烃）的临床检测和定量引发了对靶向免疫系统的新型抗炎脂质的兴趣。最近的改进方法的检测和代谢组学和脂质组学策略的进步，更精确地确定了丰富的脂肪酸硝化环境。这些新的工具已经确定共轭亚油酸（CLA）作为脂肪酸硝化的优先底物， 人类最重要的是，它已被确定，CLA硝化是很容易在人类和实验模型的CLA和无机亚硝酸盐（NO2）口服后，生物利用度。然而，胃肠外硝基-CLA的形成是否在心血管系统中具有功能益处和有益特性仍有待探索。在本文中，显示硝基-CLA形成容易转化为脉管系统中的抗炎机制。在高脂肪饮食诱导的血管炎症的实验模型中，硝基-CLA的形成有效地降低了动脉硬度，这是肥胖诱导的血管损伤的标志。硝基-CLA减少巨噬细胞的趋化性和粘附在体内的内皮细胞，从而表明在预防血管炎症反应的CLA硝化的关键作用。此外，CLA硝化显着降低肥胖诱导的炎症细胞活化，并促进强有力的抗炎表型转换，有利于巨噬细胞极化M2（替代）与M1（经典）激活。最后，硝基-CLA作为PPARγ核受体的激动剂，该核受体是参与巨噬细胞极化调节的关键转录因子。基于这一证据，该项目将测试中心假设，即增强硝基共轭亚油酸的内源性产生促进巨噬细胞向抗炎表型极化，并防止动脉粥样硬化。为了解决这一假设，提出了以下具体目标。目的1：确定硝基-CLA在促进M1至M2极化的巨噬细胞抗炎特性中的作用。目的2：确定过氧化物酶体增殖物激活受体γ（PPARγ）是介导硝基共轭亚油酸抗炎作用的关键转录因子。目的3：确定硝基-CLA介导的巨噬细胞过氧化物酶体增殖物激活受体γ激活抑制动脉粥样硬化。预期通过该提议，我们将更好地定义CLA硝化的抗炎特性，并将其口服生物利用度确定为抗动脉粥样硬化的新治疗策略。

 DESCRIPTION (provided by applicant): Targeting vascular inflammation and the adaptive immune response is emerging as novel strategy beyond lipid lowering therapies to reduce the burden of atherosclerosis, the primary cause of mortality from cardiovascular diseases in the United States. The clinical detection and quantitation of nitric oxide-dependent fatty acid nitration products (nitroalkenes) among other fatty acids species, has sparked the interest on novel anti-inflammatory lipids targeting the immune system. Recent improvements in the methodology of detection and advances in metabolomics and lipidomics strategies have more precisely determined the abundance of the fatty acid nitration milieu. These novel tools have identified conjugated linoleic acid (CLA) as the preferential substrate for fatty acid nitration in humans. Most importantly, it has been determined that CLA nitration is readily bioavailable in humans and experimental models upon oral delivery of CLA and inorganic nitrite (NO2). However, whether parenteral nitro-CLA formation has functional benefits and salutary properties in the cardiovascular system remains to be explored. Herein, it is shown that nitro-CLA formation readily translates into anti-inflammatory mechanisms in the vasculature. In an experimental model of high-fat diet induced vascular inflammation, formation of nitro-CLA efficiently reduces arterial stiffness, a hallmark of obesity- induced vascular damage. Nitro-CLA reduces macrophage chemotaxis and adhesion to the endothelium in vivo, thus suggesting a critical role of CLA nitration in the prevention of vascular inflammatory responses. In addition, CLA nitration significantly reduces obesity-induced activation of inflammatory cells and promotes a robust anti-inflammatory phenotype switch favoring macrophage polarization towards M2 (alternative) versus M1 (classical) activation. Finally, nitro-CLA serves as an agonist of the PPARγ nuclear receptor, a key transcription factor involved in the regulation of macrophage polarization. Based on this evidence, this proposed project will test the central hypothesis that enhancing the endogenous production of nitro-conjugated linoleic acid promotes macrophage polarization towards an anti-inflammatory phenotype and protects against atherosclerosis. To address this hypothesis the following Specific Aims are proposed. Aim 1: Determine the role of nitro-CLA in macrophage anti-inflammatory properties promoting an M1 to M2 polarization. Aim 2: Define PPARγ as a key transcription factor mediating nitro-CLA anti-inflammatory mechanisms in macrophages. Aim 3: Determine that nitro-CLA-mediated macrophage PPARγ activation inhibits atherosclerosis. It is expected that with this proposal we will better define the anti-inflammatory properties of CLA nitration and establish their oral bioavailability as a novel therapeutic strategy against atherosclerosis.