Pre-emptive conditioning of the ischemic heart

描述（由申请人提供）：尽管早期再灌注技术显著改善了心肌缺血的预后，但预防不可逆的缺血损伤仍然是治疗的关键方面。预防心肌缺血的一个吸引人的新治疗途径与心脏的抢先调节的可能性有关，在可能致命的缺血发生之前，可以激活生存途径。缺血预处理代表了体内心脏保护的“金标准”方法，但在临床环境中仍然难以使用。我们提出，H11激酶/Hsp22 （H11K）对于再现“延迟”或缺血预处理（SWOP）第二窗口所赋予的心脏保护特征的基因表达模式既是必要的，也是充分的。H11K是一种主要在心脏中表达的伴侣蛋白，在动物模型和患者中，其表达在各种形式的缺血性心脏病中增加。在心脏特异性转基因（TG）小鼠中，H11K的表达增加到与心脏病模型相当的水平，足以提供与缺血预处理在数量上相似的抗缺血保护。根据初步数据，我们有三个目标。第一个目标（假设1：分子机制）是更好地定义H11K促进心脏存活的信号通路。我们提出了一种原始途径，其中H11K刺激骨形态发生蛋白（BMP）受体导致磷脂酰肌醇-3激酶（PI-3K）的激活，随后Akt和哺乳动物雷帕霉素靶蛋白（mTOR）复合物2 （mTORC2）激活转录因子NF-:B。第二个目标（假设2：生理相关性）是依靠我们建立的敲除（KO）小鼠模型来证明H11K对于心脏细胞存活是必要的，特别是对于延迟预处理的机制。第三个目标（假设3：临床潜力）是确定在致死性缺血的情况下，体内短期递送H11K是否足以促进心肌细胞存活，这将为验证心脏抢先调节的概念奠定基础。我们将把体外系统（分离的心肌细胞和基因敲除）与小鼠体内模型（TG和KO）和临床前模型（猪体内基因传递）结合起来，全面解决这些目标。尽管早期再灌注技术显著改善了心肌缺血的预后，但预防不可逆的缺血损伤仍然是治疗的一个关键方面。预防心肌缺血的一个吸引人的新治疗途径与心脏的抢先调节的可能性有关，其中可以在缺血性心脏病患者中实现生存途径的激活，这些患者有随后致命缺血的风险。这些患者包括不稳定型心绞痛患者、严重反复缺血发作患者和计划行手术血运重建术的患者。在这些情况下，生存信号机制的先发制人激活将在随后的缺血应激中赋予预防性心脏保护。

DESCRIPTION (provided by applicant): Although the prognosis of myocardial ischemia has been dramatically improved by the techniques of early reperfusion, the prevention of irreversible ischemic damage remains a critical aspect of the treatment. An appealing novel therapeutic avenue for the prevention of myocardial ischemia relates to the possibility of a pre- emptive conditioning of the heart, in which an activation of survival pathways could be achieved before potentially lethal ischemia occurs. Ischemic preconditioning represents the "gold standard" method of cardioprotection in vivo but it remains difficult to use in the clinical setting. We propose that H11 kinase/Hsp22 (H11K) is both necessary and sufficient to reproduce the pattern of gene expression that characterizes the cardioprotection conferred by the "delayed" or second window of ischemic preconditioning (SWOP). H11K is a chaperone expressed predominantly in the heart, the expression of which increases in various forms of ischemic heart disease, both in animal models and in patients. Increased expression of H11K in a cardiac- specific transgenic (TG) mouse to a level comparable to that found in models of heart disease is sufficient to provide protection against ischemia that is quantitatively similar to ischemic preconditioning. Based on the Preliminary Data, we have three goals. The first goal (Hypothesis 1: Molecular Mechanisms) is to better define the signaling pathway by which H11K promotes cardiac survival. We propose an original pathway in which the stimulation of the bone morphogenetic protein (BMP) receptor by H11K results in the activation of phosphatidylinositol-3 kinase (PI-3K) and the subsequent activation of the transcription factor NF-:B by Akt and the mammalian target of rapamycin (mTOR) complex 2 (mTORC2). The second goal (Hypothesis 2: Physiological Relevance) is to rely on a knockout (KO) mouse model that we generated to prove that H11K is necessary for cardiac cell survival, and especially for the mechanisms of delayed preconditioning. The third goal (Hypothesis 3: Clinical Potential) is to determine whether short-term delivery of H11K in vivo is sufficient to promote cardiac cell survival in a context of lethal ischemia, which would lay the basis for validation of the concept of cardiac pre-emptive conditioning. We will combine an in vitro system (isolated cardiac myocytes and gene knockdown) with mouse models in vivo (TG and KO) and a pre-clinical model (gene delivery in the swine) to address these goals comprehensively. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE Although the prognosis of myocardial ischemia has been dramatically improved by the techniques of early reperfusion, the prevention of irreversible ischemic damage remains a critical aspect of the treatment. An appealing novel therapeutic avenue for the prevention of myocardial ischemia relates to the possibility of a pre- emptive conditioning of the heart, in which an activation of survival pathways could be achieved in patients with ischemic heart disease who are at risk for a subsequent lethal ischemia. These patients would include those with unstable angina, or with severe and repetitive ischemic episodes, and patients scheduled for surgical revascularization. In these situations, the pre-emptive activation of survival signaling mechanisms would confer a prophylactic cardioprotection during the following ischemic stress.