Novel mechanisms by which aspirin might protect against atherosclerosis

描述(申请人提供)：阿司匹林(‘乙酰水杨酸’)抑制前列腺素(PGs)的形成，导致炎症、肿胀、疼痛和发烧。最近的研究还表明，阿司匹林可能还有其他作用模式，包括诱导一氧化氮合成。我们最近观察到阿司匹林被人血浆和高密度脂蛋白亚组分水解为水杨酸，水杨酸是一种有效的抗氧化剂和羟基自由基捕捉剂。阿司匹林的代谢可能与对氧磷酶1(PON 1)类型的酶有关，“芳基酯酶”的底物参与了该酶的降解。PON 1是在肝脏中合成的，该酶蛋白也被报道可以延缓低密度脂蛋白(LDL)中过氧化脂质的积聚，并具有将过氧化脂质还原为氢氧化物的能力。据报道，在心血管疾病(CVD)和糖尿病中，PON 1活性降低。具体目的：结合文献报道服用阿司匹林或他汀类药物的人血浆PON-1活性升高，以及阿司匹林和对氧磷诱导PON-1基因表达(初步结果)，我们推测PON-1基因可能是由其底物诱导的。为了进一步探索这些观察结果，我们提出了以下具体目标：1.确定PON-1是否参与阿司匹林的水解。使用体外方法和PON-1缺陷小鼠，我们将确定PON-1是否在血浆中阿司匹林的水解中起作用。2.确定PON-1活性是否参与阿司匹林的抗动脉粥样硬化作用。使用PON 1-/-/apo E-/-小鼠，我们将确定水杨酸盐和阿司匹林是否具有预防动脉粥样硬化的能力。确定eNOS活性是否在阿司匹林的抗动脉粥样硬化活性中起重要作用。利用eNOS/apo E-/-小鼠，我们将确定PON-1在这些动物中的活性是否增加，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.检测阿司匹林是否诱导PON-1基因表达。利用Hep G2细胞和完整动物，我们将确定PON-1的共同底物对PON-1基因表达的诱导作用，并对诱导机制进行探讨。这些研究将为设计更好类别的PON激动剂铺平道路，这些激动剂不仅可以作为重要的阻滞剂，不仅可以预防动脉粥样硬化，还可以预防糖尿病和其他已注意到PON 1缺陷的疾病。与公众健康相关：阿司匹林(乙酰水杨酸)对炎症、肿胀、疼痛和发烧有效。最近的研究还表明，阿司匹林可能还有其他作用模式。我们观察到阿司匹林被人血浆和高密度脂蛋白水解为水杨酸，可能是通过对氧磷酶1(PON 1)。在这一应用中，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.