MYELOPEROXIDASE, OXIDANT STRESS AND ATHEROGENESIS

髓过氧化物酶、氧化应激和动脉粥样硬化

• 批准号: 6458898
• 负责人: Stanley L Hazen
• 金额: $ 6.49万
• 依托单位: CLEVELAND CLINIC FOUNDATION
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6458898
• 关键词: aldehydes; aminoacid metabolism; atherosclerosis; biomarker; clinical research; enzyme mechanism; enzyme substrate; gas chromatography mass spectrometry; human subject; hydrogen peroxide; lipid peroxides; low density lipoprotein; macrophage; monocyte; myeloperoxidase; nitrites; oxidative stress; smoking; urinalysis

Atherosclerosis is a chronic inflammatory process where oxidative damage within the artery wall is implicated in the pathogenesis of the disease. Mononuclear phagocytes, an inflammatory cell capable of generating a variety of oxidizing species, are early components of arterial lesions. Their normal functions include host defense and surveillance through regulated generation of diffusible radical species, reactive oxygen or nitrogen species and HOCI (hypochlorous acid). However, under certain circumstances, an excess of these oxidizing species can overwhelm local antioxidant defenses and lead to oxidant stress and oxidative tissue injury, processes implicated in the pathogenesis of atherosclerosis. This proposal focuses on oxidation reactions catalyzed by myeloperoxidase (MPO) and the potential utility of protein oxidation products of distinct oxidation pathways to serve as non-invasive markers of oxidant stress in vivo. MPO is an abundant heme protein secreted from activated phagocytes and is present in human atherosclerotic lesions. MPO amplifies the oxidizing potential of H2O2 by using it as substrate to generate reactive halogen, aldehyde, nitrogen and diffusible radical species. We have recently shown that MPO is one pathway for protein and lipoprotein oxidation in vivo. Multiple distinct products of MPO are enriched in human atherosclerotic lesions and LDL recovered from human atheroma. However, the biological consequences of these MPO-catalyzed reactions are unknown. We will focus on two novel oxidation pathways recently identified for the enzyme: i) MPO can use H2O2 and nitrite (NO2-), the autoxidation product of NO, as co-substrates to form reactive nitrogen species; and ii) MPO generates a family of reactive aldehydes in high yield via HOCI-mediated oxidation of plasma amino acids. The overall goals of this proposal are to test the hypothesis that specific myeloperoxidase-generated oxidation products contribute to oxidative stress, cellular injury and convert LDL into an atherogenic form. We will determine whether monocytes employ MPO-generated reactive nitrogen species to mediate LDL protein nitration, lipid peroxidation, and the conversion of the lipoprotein into a form which promotes cholesterol accumulation in cells of the artery wall. We will establish whether structurally defined aldehydes derived from amino acid oxidation promote cell injury and oxidant stress, features implicated in the pathogenesis of inflammation and vascular disease. Finally, we will explore the role of urinary levels of amino acid oxidation products as non-invasive markers of oxidative stress in smokers and individuals with cardiovascular disease.

动脉粥样硬化是一种慢性炎症过程，在该过程中，动脉壁内的氧化损伤与疾病的发病机理有关。 单核吞噬细胞是一种能够产生多种氧化物种的炎性细胞，是动脉病变的早期成分。 它们的正常功能包括通过受调节的扩散自由基物种，活性氧或氮种和HOCI（次氯酸酸）的调节来进行防御和监视。 但是，在某些情况下，过量的这些氧化物种会压倒局部抗氧化剂防御，并导致氧化剂应激和氧化组织损伤，这与动脉粥样硬化的发病机理有关。该提案的重点是由脊髓过氧化物酶（MPO）催化的氧化反应，以及具有独特的氧化途径的蛋白氧化产物的潜在效用，以作为体内氧化胁迫的非侵入性标志物。 MPO是一种从活化的吞噬细胞分泌的丰富血红素蛋白，并存在于人动脉粥样硬化病变中。 MPO通过将其用作底物来产生反应性卤素，醛，氮和扩散自由基物种来扩增H2O2的氧化潜力。 我们最近表明，MPO是体内蛋白质和脂蛋白氧化的一种途径。 MPO的多种不同产物富含人动脉粥样硬化病变，并从人动脉粥样硬化中回收。 但是，这些MPO催化反应的生物学后果尚不清楚。 我们将重点关注最近针对酶确定的两种新型氧化途径：i）MPO可以使用H2O2和亚硝酸盐（NO2-），即NO的自氧化产物，作为共蛋白酶，以形成反应性氮种； ii）MPO通过HOCI介导的血浆氨基酸氧化产生高产量的反应性醛家族。 该提案的总体目标是检验以下假设：特定的髓过氧化物酶生成的氧化产物有助于氧化应激，细胞损伤并将LDL转化为动脉粥样硬化形式。我们将确定单核细胞是否采用MPO生成的活性氮种来介导LDL蛋白硝化，脂质过氧化和脂蛋白转化为促进动脉壁细胞中胆固醇积累的形式。 我们将确定源自氨基酸氧化的结构定义的醛是否促进了细胞损伤和氧化剂应激，这与炎症和血管疾病的发病机理有关。 最后，我们将探索氨基酸氧化产物的尿液水平作为吸烟者和患有心血管疾病患者的氧化应激的非侵入性标志物的作用。