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

描述（由申请人提供）：2型糖尿病（T2 DM）被ADA和AHA指定为心血管风险因素，是我们社会中日益严重的问题。血小板活化在血管壁凝块形成中起着至关重要的作用，抗血小板治疗使具有心血管风险（包括T2 DM）的个体受益。血小板活化在T2 DM进展过程中增加，这是绝经后T2 DM女性的重要问题，因为她们更容易发生血栓形成、MI和卒中。为了更好地治疗T2 DM的心血管发病率和死亡率，需要新的治疗方法来抑制血小板活化。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变化已被证明可介导止血功能的变化。脂肪酸部分受12-脂氧合酶（12-LOX）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。虽然已经报道12-LOX表现出促血栓形成和抗血栓形成作用，但是我们最近已经表明12-LOX可以氧化许多游离脂肪酸，包括ω-3（ω-3）和ω-6脂肪酸，其功能是负调节血小板反应性并抑制血小板活化。因此，我们推测，脂肪酸调节12-LOX或直接抑制12-LOX可能是血小板反应性可以控制的替代机制。12-LOX对T2 DM患者omega-3和omega-6脂肪酸的调节可能为减弱这些患者的血小板活化提供了一种新方法。因此，将研究血小板中12-LOX代谢物调节的机制及其在T2 DM中预防血栓形成的潜在益处。我们将1）描述脂肪酸及其对血小板活化的机制。 12-LOX代谢物。与健康受试者相比，T2 DM中脂肪酸含量代谢产物形成的差异可能解释了为什么他们的血小板过度活跃，易于凝血和血栓形成。我们还将2）确定补充脂肪酸或体内抑制12-LOX是否对血小板活化具有保护作用。使用12-LOX基因敲除小鼠模型，我们将确定是否改变血小板中的脂肪酸含量或抑制野生型小鼠中的12-LOX活化对血小板活化、血栓形成和血管闭塞具有保护作用。最后，我们将3）确定补充脂肪酸作为一种调节绝经后T2 DM女性血小板活化的方法的潜在临床获益。在这项临床研究中，T2 DM患者将补充β-3脂肪酸、β-6脂肪酸或安慰剂，持续60天。 并评估血小板反应性和12-LOX代谢物形成，以确定脂肪酸补充是否可作为T2 DM中可行的抗血小板方法。本研究将描述脂肪酸在12-LOX介导的类花生酸形成和抗血小板活化中的作用。它还将确定哪些膳食脂肪酸补充剂可以通过抑制不必要的血小板活化直接使T2 DM患者受益。最后，这项研究将提供重要的洞察替代方法，如12-LOX抑制，以调节 在不断增长的T2 DM人群中的血小板活性。

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.