Pre-emptive conditioning of the ischemic heart

描述(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，但预防不可逆转的缺血损伤仍然是治疗的关键方面。预防心肌缺血的一种新的治疗途径与心脏的先期调节的可能性有关，在这种情况下，在潜在的致命性缺血发生之前，可以激活生存通路。缺血预适应是活体心脏保护的“金标准”方法，但在临床上仍难以应用。我们认为，H11激酶/Hsp22(H11K)是复制基因表达模式的必要条件和充分条件，这种模式表征了“延迟”或第二窗口的缺血预适应(SWOP)所提供的心脏保护。H11K是一种主要在心脏表达的伴侣蛋白，在各种形式的缺血性心脏病中表达增加，在动物模型和患者中都是如此。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中发现的水平相当的水平，足以提供对缺血的保护，这在数量上类似于缺血预适应。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)是为了更好地定义H11K促进心脏存活的信号通路。我们提出了一个原始的途径，即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)激活，随后Akt和哺乳动物雷帕霉素(MTOR)复合体2(MTORC2)激活转录因子NF-B。第二个目标(假设2：生理学相关性)是依靠我们建立的基因敲除(KO)小鼠模型来证明H11K对心肌细胞生存是必要的，特别是对延迟预适应的机制。第三个目标(假设3：临床潜力)是确定体内短期注射H11K是否足以在致死性缺血的情况下促进心肌细胞的存活，这将为验证心脏先行预适应的概念奠定基础。我们将结合体外系统(分离的心肌细胞和基因敲除)与体内的小鼠模型(TG和KO)和临床前模型(猪的基因传递)来全面解决这些目标。公共卫生相关性：项目简介尽管早期再灌流技术显著改善了心肌缺血的预后，但预防不可逆转的缺血损伤仍然是治疗的关键方面。预防心肌缺血的一个有吸引力的新的治疗途径与心脏的先期调节的可能性有关，在这种可能性中，存在随后发生致命性缺血的风险的缺血性心脏病患者可以激活生存通路。这些患者将包括那些不稳定心绞痛，或有严重和重复的缺血发作，以及计划进行手术血管重建术的患者。在这些情况下，抢先激活生存信号机制将在随后的缺血应激期间提供预防性的心脏保护。

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.