Role of 12-lipoxygenase in platelet reactivity and type 2 diabetes mellitus

描述(申请人提供)：2型糖尿病(T2 DM)，被ADA和AHA指定为心血管危险因素，在我们的社会中是一个日益严重的问题。血小板活化在血管壁凝块的形成中起着关键作用，抗血小板治疗使包括T2 DM在内的心血管疾病风险人群受益。在T2 DM的进展过程中，血小板活化增加，这对患有T2 DM的绝经后妇女非常重要，因为她们更容易发生血栓形成、心肌梗死和中风。为了更好地治疗T2 DM的心血管并发症和死亡率，有必要采用新的治疗方法来抑制血小板的激活。此外，膳食脂肪酸可能在这一调节过程中发挥作用，因为脂肪酸摄入量的多样性已被证明介导止血功能的变化。脂肪酸在一定程度上受12-脂氧合酶(12-LOX)的调节，我们最近的工作表明抑制12-LOX可能是限制血小板活性的一种方法。虽然12-LOX被报道具有促血栓和抗血栓作用，但我们最近发现，12-LOX可以氧化一些游离脂肪酸，包括omega-3(omega-3)和omega-6脂肪酸，它们的功能是负向调节血小板的反应性和抑制血小板的激活。因此，我们推测12-LOX对脂肪酸的调节或直接抑制12-LOX可能是控制血小板反应性的替代机制。12-LOX对T2 DM患者omega-3和omega-6脂肪酸的调节可能为减轻这些患者的血小板活化提供了一种新的方法。因此，我们将对12-LOX代谢产物在血小板中的调节机制及其对T2 DM血栓形成的潜在保护作用进行研究。我们将1)描述脂肪酸激活血小板的机制和它们的 12-LOX代谢物。与健康受试者相比，T2 DM患者在脂肪酸含量、代谢产物形成方面的差异可能解释了为什么他们的血小板过度活跃，容易凝血和血栓形成。我们还将确定补充脂肪酸或体内抑制12-LOX是否对血小板激活具有保护作用。利用12-LOX基因敲除小鼠模型，我们将确定改变血小板中脂肪酸含量或抑制野生型小鼠的12-LOX激活是否对血小板激活、血栓形成和血管闭塞具有保护作用。最后，我们将确定补充脂肪酸作为一种调节绝经后2型糖尿病患者血小板活化的方法的潜在临床益处。在这项临床研究中，T2 DM患者将补充�-3脂肪酸、�-6脂肪酸或安慰剂，为期60天 并将评估血小板反应性和12-LOX代谢物的形成，以确定补充脂肪酸是否可以作为一种可行的T2 DM抗血小板方法。这项研究将描述脂肪酸在12-LOX介导的二十烷类化合物形成和防止血小板激活中的作用。它还将确定哪些膳食脂肪酸补充剂可能通过抑制不必要的血小板激活而直接受益于T2 DM患者。最后，这项研究将对替代方法，如12-LOX抑制，以调节 不断增长的2型糖尿病人群的血小板活性。

DESCRIPTION (provided by applicant): Type 2 diabetes (T2DM), designated as a cardiovascular risk factor by the ADA and AHA, is a growing problem in our society. Platelet activation plays a crucial role in clot formation in the vessel wall and anti- platelet therapy benefits individuals with cardiovascular risks including T2DM. Platelet activation is increased during the progression of T2DM and is of significant concern to postmenopausal women with T2DM as they are more prone to thrombosis, MI, and stroke. To better treat cardiovascular morbidity and mortality in T2DM, novel therapeutic approaches are warranted to inhibit platelet activation. Additionally, dietary fatty acids may play a role in this regulatory process as variabiity in fatty acid intake has been shown to mediate changes in hemostatic function. Fatty acids are regulated in part by 12-lipoxygenase (12-LOX) and our recent work has suggested inhibiting 12-LOX may be one approach to limiting platelet activity. While 12-LOX has been reported to exhibit both pro and anti-thrombotic effects, we have recently shown that 12-LOX can oxidize a number of free fatty acids, including the omega-3 (omega-3) and omega-6 fatty acids, which function to negatively regulate platelet reactivity and inhibit platelet activation. Therefore we hypothesize that fatty acid regulation by 12-LOX or direct inhibition of 12-LOX may be alternative mechanisms by which platelet reactivity can be controlled. 12-LOX regulation of omega-3 and omega-6 fatty acids in T2DM may present a novel approach for attenuating platelet activation in these patients. Therefore, the mechanism of 12-LOX metabolite regulation in platelets and their potential benefit in protection against thrombosis in T2DM will be investigated. We will 1) characterize the mechanism of platelet activation by fatty acids and their 12-LOX metabolites. Differences in fatty acid content metabolite formation in T2DM relative to healthy subjects may explain why their platelets are hyperactive and prone to clotting and thrombosis. We will also 2) determine if fatty acid supplementation or in vivo inhibition of 12-LOX is protective against platelet activation. Using a 12-LOX knockout mouse model, we will identify if altering the fatty acid content in the platelet or inhibiting 12-LOX activation in wildtype mice is protective against platelet activation, thrombosis, and vessel occlusion. Finally, we will 3) determine the potential clinical benefit of fatty acid supplementation as an approach to regulate platelet activation in postmenopausal women with T2DM. In this clinical study, T2DM patients will be supplemented with either �-3 fatty acid, �-6 fatty acid, or a placebo, for 60 days and platelet reactivity and 12-LOX metabolite formation will be assessed in order to determine if fatty acid supplementation can act as a viable anti-platelet approach in T2DM. This study will delineate the role of fatty acids in 12-LOX-mediated eicosanoid formation and protection against platelet activation. It will also determine which dietary fatty acid supplements may directly benefit T2DM patients through inhibition of unwanted platelet activation. Finally, this study will give significant insight into alternative approaches such as 12-LOX inhibition in order to regulate platelet activity in the growing T2DM population.