SIGNAL REGULATION OF CARDIAC CYTOKINE SYNTHESIS AND MECHANICAL FUNCTION

研究表明，心肌细胞合成TNF可能导致许多损伤的心功能障碍，包括脓毒性休克，热损伤，充血性心脏病。心脏内的区室化TNF产生显著高于全身TNF水平所反映的水平，并且局部产生的TNF可能不被循环TNF受体缓冲，循环TNF受体对心肌内产生的TNF的接近有限。本提案的总体目标是确定调节姿势心肌TNF产生的信号转导机制，并确定TNF影响心脏功能的机制。我们假设IkappaB的磷酸化和降解以及NF-κ B的核转位是心肌内的关键调节剂和姿势TNF转录事件。我们进一步假设，烧伤介导的心脏TNF合成增加诱导介导的级联反应，这有助于心肌细胞骨架的重塑，改变肌原纤维与Ca 2+的结合，并产生心脏损伤。本研究将探讨TNF是烧伤后炎症反应的近端介质这一整体假说：具体研究目标有五个：1）烧伤对心肌TNF mRNA和蛋白的影响，确定心肌TNF合成的细胞来源和亚细胞定位; 2）确定NF-κ B在姿势心肌细胞TNF合成中的作用，并鉴定由皮肤烧伤触发的调节NF-κ B/TNF合成的促分泌素; 3）确定在心肌细胞中调节NF-κ B活化/TNF合成的细胞内信号传导机制; 3）确定在心肌细胞中调节NF-κ B活化/TNF合成的细胞内信号传导机制; 4）确定烧伤创伤后心脏来源的TNF是否通过诱导iNOS、表达IL-1或产生心脏鞘氨醇而发挥负性肌力作用;和5）确定TNF是否通过改变细胞对Ca 2+的处理来调节心脏功能，这反过来促进凝溶胶蛋白介导的肌细胞细胞骨架重塑。我们将集中于确定诱导剂（S）和信号转导途径，导致TNF分泌的心肌细胞，以及TNF产生心肌损伤和功能障碍的具体机制。这些研究应该允许开发治疗策略，不仅为烧伤创伤的受害者，而且为心脏收缩/舒张受损导致死亡率增加的患者群体提供显着的心脏保护。

Studies suggest that TNF synthesis by cardiomyocytes may contribute to cardiac dysfunction in a number of insults including septic shock, thermal injury, congestive heart disease. Compartmentalized TNF production within the heart by be significantly higher than is reflected by systemic TNF levels, and locally produced TNF may not be buffered by circulating TNF receptors which would have limited access to intramyocardially produced TNF. The overall objectives of this proposal are to define the signal transduction mechanisms which regulate posture myocardial TNF production and to define the mechanisms by which TNF altars cardiac function. We hypothesize that phosphorylation and degradation of IkappaB and nuclear translocation of NF-kappaB are critical modulators and posture TNF transcriptional events within the myocardium. We further hypothesize that burn-mediated increases in cardiac TNF synthesis induce a cascade of mediators which contribute to remodeling of the cardiomyocyte cytoskeleton, alter myofibrillar binding to Ca2+ and produce cardiac injury. We will examine the global hypothesis that TNF is a proximal mediator of the overall inflammatory response to burn trauma: Five specific aims will be: 1) determine the effects of burn trauma on myocardial TNF mRNA and protein and determine the cellular source and subcellular location of myocardial TNF synthesis; 2) determine the role of NF-kappaB in posture cardiomyocyte TNF synthesis and identify secretagogues triggered by cutaneous burn injury which regulate NF-kappaB/TNF synthesis; 3) determine the intracellular signaling mechanisms which regulate NF-kappaB ACTIVATION/TNF synthesis; 3) determine the intracellular signaling mechanisms which regulate NF-kappaB activation/TNF synthesis in cardiomyocytes; 4) determine if cardiac derived TNF after burn trauma exerts negative inotropic effects via induction of iNOS, expression of IL-1, or production of cardiac sphingosine; and 5) determine if TNF modulates if TNF modulates cardiac function by altering cellular handling of Ca2+, which in turn, promotes gelsolin-mediated myocyte cytoskeletal remodeling. We will focus on identifying the inducer(s) and signal transduction pathways which lead to TNF secretion by cardiomyocytes as well as specific mechanisms by which TNF produces myocardial injury and dysfunction. These studies should allow development of therapeutic strategies that would provide significant cardioprotection not only for victims of burn trauma but also for patient populations in whom impaired cardiac contraction/relaxation contribute to increased mortality.