Despite advances in the management of septic patients, a large number of such patients subsequently die from multiple organ failure. This could be due to the fact that some of the subtle changes in cellular function during early sepsis are not identified and consequently missed, leading to delayed treatment of the septic patient. Our results have shown that hepatocellular dysfunction occurs very early in sepsis, which is associated with elevated plasma TNF and IL-6 levels. Administration of recombinant TNF in normal rats at a dose which does not alter hemodynamics, decreases hepatocellular function and increases plasma level of IL-6. We, therefore, propose that TNF and IL-6 are responsible for producing hepatocellular dysfunction in sepsis and that blockade of their production and biological activities will prevent or delay the occurrence of this dysfunction. Thus, our hypothesis is that administration of pharmacologic agents (that downregulate TNF and IL-6) after the onset of sepsis attenuates the progressive deterioration of hepatocellular and other cell functions and reduces sepsis-induced late mortality. Studies are proposed to determine: 1) the mechanisms by which hepatocellular function is depressed in early sepsis and whether neutralization of the biological activities of TNF and IL-6 with TNF- binding proteins and anti-IL-6 antibody prevents hepatocellular dysfunction; 2) whether pentoxifylline, ATP-MgC1/2, or chemically modified heparin decreases TNF and IL-6 and subsequently prevents hepatocellular dysfunction in early sepsis and, if so, the mechanism of the beneficial effects of these agents; 3) whether the proposed agents have any beneficial effect on other organ functions such as renal and gut absorptive function, and whether sepsis-induced mortality is reduced by the use of these agents in conjunction with fluid resuscitation and septic focus excision. Plasma TNF, IL-6, cell-associated TNF and other selected mediators (i.e., PGE2, catecholamines) will be measured. TNF and IL-6 gene expression, cAMP, cGMP, Ca2+, IP3, protein kinase C, and beta-adrenergic receptors will be determined in isolated Kupffer cells (KC) and hepatocytes. In situ hybridization will be used to localize TNF and IL-6 mRNAs. The hemodynamic parameters and/or organ functions to be measured include hepatocellular, renal and gut absorptive function, hepatic and renal perfusion, and cardiac output. Hepatocyte-KC co- culture will be used to determine if KC from septic animals decreases hepatocyte protein synthesis from normal animals. The proposed studies should provide useful information that allows us not only to better understand the mechanisms of hepatocellular dysfunction in early sepsis, but also to identify and intercept hepatocellular dysfunction at an earlier time in the course of sepsis and thereby prevent late multiple organ failure and mortality. The long-term goals of the applicant's research are to determine the mechanisms responsible for cellular dysfunction observed in early sepsis, and thus to identify agents which can be administered safely in trauma and septic patients in early stages to prevent cell/organ dysfunction. With an excellent environment for conducting the proposed work in the Center for Surgical Research, this award will play a critical role in the applicant's development as an independent investigator.
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