Cardiac dysfunction is a primary contributor to morbidity and mortality in patients suffering burn trauma or sepsis. We have previously demonstrated that this cardiac dysfunction is mediated, at least in part, by the cytokine tumor necrosis factor-alpha (TNF) which is locally produced in the myocardium. Recently, we have determined that burn trauma also markedly increased apoptosis in both the myocardium and the gastrointestinal system, and that apoptosis is temporally associated with physiologic organ dysfunction. The goal of this proposal is to determine the molecular mechanisms by which burn trauma induces apoptosis, and to elucidate the role of apoptosis in the pathogenesis of organ injury both in the heart and the endothelium. First, we will determine whether TNF is responsible for apoptosis in vivo, and whether apoptosis is associated with alterations in the expression of pro- and anti-apoptosis genes. We will also utilize an in vitro model to precisely characterize the molecular mechanisms of apoptosis, including the role of nitric oxide, intracellular Ca2+, and death domain signaling via caspase 8. Next, through the use of physiological inhibitors and novel transgenic mice in which NF-kappaB is sequestered, we will determine whether the nuclear translocation of NF-kappaB is sequestered, we will determine whether the nuclear translocation of NF-kappaB following burn trauma is associated with apoptosis protection, and whether this protection is due to enhanced expression of anti-apoptotic genes. Finally, through the use of novel transgenic animals in which cardiac myocyte apoptosis protection, and whether this protection is due to enhanced expression of anti-apoptotic genes. Finally, through the use of novel transgenic animals in which cardiac myocyte apoptosis is specially inhibited we will determine whether apoptosis is responsible for cardiac physiologic dysfunction, or whether apoptosis is an adaptive mechanism which mitigates inflammation and preserves physiological function. By understanding the molecular mechanisms and role of apoptosis in burn shock, it may be possible to develop specific targeted therapeutic strategies for the treatment of burns, sepsis, and primary cardiac diseases associated with myocardial synthesis of TNF.
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