Calpain and Calpastatin Regulation of Reperfusion Injury

描述(申请人提供)：先天性心脏病是出生一年内因出生缺陷而死亡的第一大原因。虽然大多数先天性心脏病的矫正或姑息手术可以在婴儿期进行，但修复仍然与死亡率和发病率有关，超过了大多数儿科外科手术。体外循环和心肌缺血通常是修复所必需的，可能会导致暂时性的心肌功能障碍，如心肌顿抑，或永久性的，如细胞凋亡。婴儿和儿童的心肌保护策略是有限的，而且往往只是成人治疗的推论。缺血心脏的再灌流可以刺激半胱氨酸蛋白酶及其内源性抑制物--钙蛋白酶的活性。钙蛋白酶的活性与钙调节的收缩中断、收缩蛋白的降解和细胞死亡增加有关。这项建议的长期目标是确定儿童缺血和再灌注后心肌功能障碍的机制。目前的目标是确定促进干预措施发展的途径，以减少术后再灌注损伤。该假说认为钙蛋白酶和钙糊蛋白通路是未成熟心肌再灌流损伤的关键介质。本项目的具体目的是：1)在幼年动物模型中确定Calain和Calastatin对核因子-kappaB的调节在再灌注相关心肌功能障碍中的作用；2)确定Calain在介导与缺血心肌再灌注相关的心肌细胞凋亡中的作用；以及3)确定再灌注后Calastatin活性的调节机制。采用仔猪体外循环停循环模型和体外培养新生心肌细胞的方法，研究了钙蛋白酶和钙糊精在未成熟心肺系统再灌注损伤中的作用。通过测定这些通路中钙蛋白酶和钙蛋白酶蛋白的调节，确定减少儿科患者术后心肌功能障碍的治疗目标。

DESCRIPTION (provided by applicant): Congenital heart disease is the number 1 cause of death from birth defects in the first year of life. Although corrective or palliative surgery for most congenital heart defects can be undertaken in infancy, repair is still associated with mortality and morbidity exceeding that of most pediatric surgical procedures. Cardiopulmonary bypass and myocardial ischemia is typically required for repair and can result in myocardial dysfunction that is temporary, such as myocardial stunning, or permanent, such as occurs with apoptosis. Myocardial protective strategies for infants and children are limited and often are only extrapolations of adult therapies. Reperfusion of ischemic heart stimulates the activity of cysteine proteases called calpains and their endogenous inhibitor, calpastatin. Calpain activity is associated with interruption of calcium-regulated contraction, degradation of contractile proteins, and enhanced cell death. The long-term goal of this proposal is to define mechanisms of myocardial dysfunction after ischemia and reperfusion in children. The immediate goal is to identify pathways that facilitate development of interventions to reduce postoperative reperfusion injury. The hypothesis is that calpain and calpastatin pathways are critical mediators of reperfusion injury in immature myocardium. The specific aims of this project are: 1) determine the role of nuclear factor-kappaB regulation by calpain and calpastatin in myocardial dysfunction associated with reperfusion in an immature animal model, 2) define the role of calpain in mediating cardiac apoptosis associated with reperfusion of ischemic myocardium, and 3) determine regulatory mechanisms of calpastatin activity after reperfusion. A piglet model of cardiopulmonary bypass and circulatory arrest and in vitro culture of neonatal cardiomyocytes examine the roles of calpain and calpastatin in reperfusion injury of the immature cardiopulmonary system. Determining calpain and calpastatin regulation of these pathways identifies therapeutic targets to reduce postoperative myocardial dysfunction in pediatric patients.