Novel mechanisms by which aspirin might protect against atherosclerosis

描述（由申请人提供）：阿司匹林（“乙酰水杨酸”）抑制引起炎症、肿胀、疼痛和发烧的前列腺素（pg）的形成。最近的研究也表明阿司匹林可能有其他的作用方式，包括诱导一氧化氮的合成。我们最近观察到阿司匹林被人体血浆和HDL亚组分水解成水杨酸，水杨酸是一种有效的抗氧化剂和羟基自由基捕获剂。水解是由“芳基酯酶”的底物竞争的，这促使我们提出对氧磷酶1 （PON 1）类型的酶可能参与阿司匹林的代谢。PON 1在肝脏中合成，据报道，这种酶蛋白也可以延缓低密度脂蛋白（LDL）中脂质过氧化物的积累，并具有将脂质过氧化物还原为氢氧化物的能力。据报道，PON 1活性在心血管疾病（CVD）和糖尿病中降低。具体目的：结合文献中观察到服用阿司匹林或他汀类药物的患者血浆PON 1活性升高，阿司匹林和对氧磷诱导PON 1基因表达（初步结果），我们提出PON 1基因可能受其底物诱导。为了进一步探索这些观察结果，我们提出以下具体目标：1。确定PON 1是否参与阿司匹林的水解。通过体外实验和PON 1缺失小鼠实验，我们将确定PON 1是否在血浆中阿司匹林的水解中发挥作用。2. 确定PON 1活性是否对阿司匹林的抗动脉粥样硬化活性至关重要。使用PON 1 -/-/载脂蛋白E-/-小鼠，我们将确定水杨酸盐而非阿司匹林是否具有预防动脉粥样硬化的能力。确定eNOS活性是否对阿司匹林的抗动脉粥样硬化活性至关重要。使用eNOS/载脂蛋白E-/-小鼠，我们将确定PON-1活性是否在这些动物中增加，以及在没有eNOS的情况下，单独诱导PON 1是否足以提供动脉粥样硬化保护。3. 目的：观察阿司匹林是否诱导PON 1基因表达。使用Hep G2细胞和完整动物，我们将确定PON 1的常见底物对PON 1基因表达的诱导作用。将确定这种诱导所涉及的机制。意义：这些研究将为设计更好的PON激活剂铺平道路，这些激活剂不仅可以作为动脉粥样硬化的重要威慑物，还可以作为糖尿病和其他PON 1缺乏的疾病的重要威慑物。公共卫生相关性：阿司匹林（乙酰水杨酸）对炎症、肿胀、疼痛和发烧有效。最近的研究也表明阿司匹林可能有其他的作用模式。我们观察到阿司匹林被人血浆和HDL水解为水杨酸，可能是通过对氧磷酶1 （PON 1）。在这个应用中，我们提出阿司匹林的作用可能是由水杨酸盐介导的。我们还探讨了阿司匹林诱导PON 1的机制。

DESCRIPTION (provided by applicant): Aspirin ('acetylsalicylic acid') inhibits the formation of prostaglandins (PGs) that cause inflammation, swelling, pain and fever. Recent studies also suggest that aspirin may have other modes of action, including the induction of nitric oxide synthesis. We recently observed that aspirin is hydrolyzed to salicylic acid, a potent antioxidant and a hydroxyl radical trapping agent, by human plasma and HDL subfraction. Hydrolysis was competed for by substrates of "aryl esterases" that prompted us to propose that paraoxonase 1 (PON 1) type of enzymes might be involved in the metabolism of aspirin. PON 1 is synthesized in the liver and the enzyme protein has also been reported to retard the accumulation of lipid peroxides in low density lipoprotein (LDL) and has the ability to reduce lipid hydroperoxides to hydroxides. PON 1 activity has been reported to be decreased in cardiovascular disease (CVD), and in diabetes. Specific Aims: Coupled with the observation in literature that those who consumed aspirin or statins showed increased plasma PON 1 activity and aspirin and paraoxon induced the expression of PON 1 gene (preliminary results), we propose that that PON 1 gene might be induced by its substrates. In order to explore these observations further, we propose the following specific aims: 1. To determine whether PON 1 is involved in the hydrolysis of aspirin. Using both in vitro methodology as well as mice deficient in PON 1, we will determine whether PON 1 plays a role in the hydrolysis of aspirin in the plasma. 2. To determine whether PON 1 activity is essential for the anti-atherosclerotic activity of aspirin. Using PON 1 -/-/apo E-/- mice, we will determine whether salicylate and not aspirin has the ability to protect against atherosclerosis. To determine whether eNOS activity is essential for the anti-atherosclerotic activity of aspirin. Using eNOS/apo E-/- mice, we will determine whether PON-1 activity is increased in these animals and whether induction of PON 1 alone is sufficient to afford atherosclerotic protection in the absence of eNOS. 3. To determine whether the expression of PON 1 gene is induced by aspirin. Using Hep G2 cells and intact animals, we will determine the induction of PON 1 gene expression by common substrates of PON 1. The mechanisms involved in such induction will be determined. Implications: These studies would pave way for designing better class of PON activators that may serve as important deterrents of not only atherosclerosis but also diabetes and other diseases in which deficiencies in PON 1 have been noted. PUBLIC HEALTH RELEVANCE: Aspirin (acetylsalicylic acid) is effective against inflammation, swelling, pain and fever. Recent studies also suggest that aspirin may have other modes of actions. We observed that aspirin is hydrolyzed to salicylic acid by human plasma and HDL, presumably by paraoxonase 1 (PON 1). In this application, we propose that the actions of aspirin might be mediated by salicylate. We also explore the mechanisms by which PON 1 could be induced by aspirin.