Pre-emptive conditioning of the ischemic heart

描述（由申请人提供）：尽管心肌缺血的预后已通过早期再灌注技术得到显著改善，但预防不可逆的缺血性损伤仍然是治疗的关键方面。一种用于预防心肌缺血的有吸引力的新治疗途径涉及心脏的抢先调节的可能性，其中可以在潜在致命的缺血发生之前实现存活途径的激活。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。我们建议，H11激酶/Hsp 22（H11 K）是必要的和足够的基因表达的模式，其特征是由缺血预处理（SWOP）的“延迟”或第二窗口所赋予的心脏保护。H11 K是主要在心脏中表达的伴侣蛋白，其表达在各种形式的缺血性心脏病中增加，在动物模型和患者中都是如此。心脏特异性转基因（TG）小鼠中H11 K的表达增加到与心脏病模型中发现的水平相当的水平足以提供与缺血预处理在数量上相似的针对缺血的保护。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H11 K促进心脏存活的信号通路。我们提出了一个原始的途径，其中骨形态发生蛋白（BMP）受体的刺激H11 K的结果在激活磷脂酰肌醇-3激酶（PI-3 K）和随后激活的转录因子NF-：B的Akt和哺乳动物的雷帕霉素（mTOR）复合物2（mTORC 2）。第二个目标（假设2：生理相关性）是依赖于我们产生的敲除（KO）小鼠模型，以证明H11 K对心脏细胞存活是必需的，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）是确定在体内短期递送H11 K是否足以在致死性缺血的情况下促进心脏细胞存活，这将为心脏先发制人调节的概念的验证奠定基础。我们将结合联合收割机体外系统（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（猪中的基因递送）来全面解决这些目标。公共卫生相关性：虽然心肌缺血的预后已经通过早期再灌注技术得到显著改善，但是防止不可逆的缺血性损伤仍然是治疗的关键方面。一种用于预防心肌缺血的有吸引力的新治疗途径涉及心脏的先发制人调节的可能性，其中可以在具有随后致命性缺血风险的缺血性心脏病患者中实现存活途径的激活。这些患者包括不稳定型心绞痛患者，或严重反复缺血发作患者，以及计划进行血运重建手术的患者。在这些情况下，存活信号传导机制的抢先激活将在随后的缺血应激期间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.