Heart-platelet crosstalk: JNK, AF, and thrombogenesis

房颤是最常见的心律失常，具有很高的卒中风险和卒中相关的死亡率和发病率。 房颤和中风的患病率随着年龄和酗酒而显著增加。经典的病理生理学 房颤时心房机械性停滞促进血栓形成。因此，抗血栓治疗 一直是房颤管理的关键组成部分。然而，由于中风出血的两难境地，以及不同的风险 在血栓抑制事件中，只有大约一半的房颤患者接受了抗血栓治疗。新兴临床 这些发现正在挑战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联系 血栓形成更令人费解。这项建议的目标是填补这一知识空白，建立一个以前的 心脏和血小板之间通过含有心脏来源的循环微粒的未知串扰 激活的应激分子JNK2，揭示心脏JNK2双重功能作用的机制 血栓形成和房颤的发展。我们耐人寻味的初步发现表明，年龄和酒精驱动的 心脏中JNK的激活与血小板的激活有机械联系，因此增加了血栓的形成。这 是一个潜在的改变范式的概念。接下来，我们发现心脏细胞释放JNK微粒(JNK-MPS)，这些 然后，MPS可以通过JNK2特异性的内吞作用与血小板相互作用。因此，增加了 血小板JNK2可导致血小板钙稳态异常，增加静息状态下的血小板反应性。所有这些都是 耐人寻味的初步结果和我们之前的发现指出了以前未发现的JNK2信号串扰 在心脏和血小板之间。在本提案中，我们将使用互补的电生理方法(DUAL 电压/钙光学标测、活体共聚焦血小板钙成像、体内心房膜基因转移、体外血小板 完整的聚集、体内血栓形成和单IP3R通道记录)和生化技术 房室、血小板，甚至在单通道中全面了解心脏与心脏的关系 JNK2、血栓形成和房颤风险。JNK2对房颤倾向、血小板钙调节和静息血小板的作用 将使用几种新的心脏特异性可诱导的TG小鼠模型和操纵的JNK2来解剖反应性 (JNK1)活动(激活或失活)以及使用和不使用心房特异性JNK2抑制的老年动物 独特的体内心房画基因转移技术。有可能将动物模型的结果转化为 对于人类，我们将对可存活的人类血小板和器官捐赠者的心脏进行选择性研究。我们的具体目标 1)明确心脏JNK2(CJNK2)活化、血小板功能、血栓形成与房颤之间的联系；2) 描述心脏如何通过循环JNK2-MPS与血小板对话，调节血小板钙调节和 高反应性。这一建议结合了重要的功能测量和基础力学研究。 以及适当的替代方法。心脏特异性干预(体内心房基因转移和遗传 限制心脏JNK2活性的JNK抑制)将作为原则验证研究进行测试，并作为潜在的 预防和/或治疗血栓形成和房颤的治疗选择。

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.