Heart-platelet crosstalk: JNK, AF, and thrombogenesis

心房颤动是最常见的心律失常，具有卒中和卒中相关死亡率和发病率的高风险。 房颤和卒中的患病率随着年龄和酗酒而显著增加。经典的病理生理学 概念是AF期间心房机械性停滞促进血栓栓塞形成。因此，抗血栓治疗 是AF管理的关键组成部分。然而，由于中风出血的困境，和不同的风险， 在血栓栓塞事件中，只有大约一半的房颤患者接受抗血栓治疗。新出现的临床 这些发现挑战了我们长期以来的房颤-中风教条，留下了房颤和中风之间的因果关系。 血栓形成更加令人困惑。本提案的目标是填补这一知识空白，建立一个以前 通过含有心脏来源的循环微粒，心脏和血小板之间未被识别的串扰 激活应激分子JNK 2，并揭示心脏JNK 2的双重功能作用的潜在机制， 血栓形成和房颤发展。我们有趣的初步研究结果表明，年龄和酒精驱动的 心脏中的JNK活化与血小板活化机制相关，从而增加血栓形成。这 是一个潜在的范式转换概念。接下来，我们发现心脏细胞脱落JNK微粒（JNK-MP）， 然后MP可以通过JNK 2特异性内吞作用与血小板相互作用。因此， 血小板JNK 2可导致血小板Ca稳态异常，增加静息血小板反应性。所有这些 有趣的初步结果和我们以前的发现指出了以前未被认识的JNK 2信号串扰 心脏和血小板之间的联系在本建议中，我们将使用互补的电生理方法（双 电压/钙光学标测，活体共聚焦血小板钙成像，在体心房彩绘基因转移，离体血小板 聚集、体内血栓形成和单IP 3R通道记录）和完整的 心房，血小板，甚至在单通道，以获得心脏之间的关系的全面图片 JNK 2、血栓形成和AF风险。JNK 2对AF倾向、血小板Ca处理和静息血小板的作用 将使用几种新的心脏特异性诱导型Tg小鼠模型与操纵的JNK 2来剖析反应性 （JNK 1）活性（活化或灭活）和有和无心房特异性JNK 2抑制的老年动物，使用 独特的体内心房彩绘基因转移技术。将动物模型的结果转化为 我们将对器官捐献者的活血小板和心脏进行选择性研究。我们的具体目标 是：1）定义心脏JNK 2（cJNK 2）激活、血小板功能、血栓形成和AF之间的联系，以及2） 描述心脏如何通过循环JNK 2-MP与血小板对话，控制血小板Ca处理， 高反应性该建议整合了重要的功能测量和基本的机理研究 沿着适当的替代方法。心脏特异性干预（体内心房基因转移和遗传 JNK抑制），限制心脏JNK 2活性将被测试为原则上的证据研究，并探讨作为潜在的 预防和/或治疗血栓形成和AF的治疗选择。

Atrial fibrillation is the most common arrhythmia with a high risk of stroke and stroke-associated mortality and morbidity. The prevalence of AF and stroke, increases markedly with age and alcohol abuse. The classic pathophysiological concept is atrial mechanical stasis during AF promotes thromboembolism formation. Thus, antithrombotic therapy has been a key component of AF management. However, due to the stroke-bleeding dilemma, and the varying risk of thromboemobolic events, only about half of all AF patients receive antithrombotic therapies. Emerging clinical findings are challenging our long-standing AF-stroke dogma, leaveing the causal link between AF and thrombogenesis even more baffling. The goal of this proposal is to fill this knowledge gap, establish a previously unrecognized crosstalk between heart and platelets through circulating microparticles containing heart-origin activated stress molecule JNK2 and reveal the underlying mechanism of the dual functional role of cardiac JNK2 in both thrombogenesis and AF development. Our intriguing preliminary findings suggest that age- and alcohol-driven JNK activation in the heart is mechanistically linked to the platelet activation and thus increased thrombogenesis. This is potentially a paradigm-shifting concept. Next, we found heart cells shed JNK-microparticles (JNK-MPs) and these MPs could then interact with platelets through an action of JNK2-specific endocytosis. Consequently, increased platelet JNK2 could lead to abnormal platelet Ca homeostasis and increase resting platelet reactivity. All these intriguing preliminary results and our previous findings point to a previously unrecognized JNK2-signaling crosstalk between the heart and platelets. In this proposal, we will use complementary electrophysiological approaches (dual voltage/Ca optical mapping, intravital confocal platelet Ca imaging, in vivo atrial painting gene transfer, ex vivo platelet aggregation, in vivo thrombus formation, and single IP3R channel recording) and biochemical techniques in intact atria, platelets, and even in single channels to gain a comprehensive picture of the relationship between cardiac JNK2, thrombogenesis and AF risk. The JNK2 actions on AF propensity, platelet Ca handling, and resting platelet reactivity will be dissected using several novel cardiac specific inducible Tg mouse models with manipulated JNK2 (JNK1) activity (activated or inactivated) and aged animals with and without atrial-specific JNK2 inhibition using a unique in vivo atrial painting gene transfer technique. To potentially translate the results from animal models to humans, we will perform selective studies in viable human platelets and hearts from organ donors. Our specific aims are: 1) Define the link between cardiac JNK2 (cJNK2) activation, platelet function, thrombogenesis and AF and 2) Delineate how the heart talks to platelets through circulating JNK2-MPs, governing platelet Ca handling and hyper-reactivity. This proposal integrates important functional measurements and fundamental mechanistic studies along with appropriate alternative approaches. Cardiac specific interventions (in vivo atrial gene transfer & genetic JNK inhibition) that limit cardiac JNK2 activity will be tested as proof-in-principle studies and explored as potential therapeutic options to prevent and/or treat thrombogenesis and AF.