Our hypothesis is that bacterial endotoxin evokes the release of mediators from the reticuloendothelial system that mediate alterations in hormone regulated metabolism in the liver. Evidence obtained in our laboratory during the first 21/2 years of this project suggest immunomodulatory monokines, released following endotoxin administration interact with glucocorticoid actionon gene expression. In the continuation of this study we propose to characterize the role of monokines, such as IL 1, TNF, and IFN, in altered glucocorticoid action during endotoxemia. This will be done by titrating the inhibitory activity of mediator- rich plasma (obtained from CF-1 mice infected with BCG and challenged with 2 micrograms of bacterial endotoxin) in C3H/HeJ mice and Reuber H35 rat hepatoma cell (RHC) cultures. Altered glucocorticoid induction of tryptophan oxygenase (TO), tyrosine aminotransferase (TAT), phosphoenolpyruvate carboxykinase (PEPCK), and glyogen synthase (GS) will be monitored after monokine treatment. Impaired induction of these liver enzymes will be correlated with decreased hepatic cytosolic binding of dexamethasone. In addition we will titrate the inhibitory activity of factors released from endotoxin treated Kupffer cells. Cross- adsorption of mediator-rich plasma and Kupffer cell fluids with monospecific antibodies to known monokines will assess the possible synergistic or antagonistic effects of monokines on altered glucocorticoid action. In the proposed study we will also assess the influence of glucocorticoids on the monokine mediators that are found to affect glucocorticoid action during endotoxic shock. We will measure the inhibition of induction of TO, TAT, PEPCK and GS in adrenal-ectomized (adrx) mice and adrx mice reconstituted with exogenous steroid. Recombinant IL 1, TNF and IFN will be used in both mice and RHC to test the influence of steroids on monokine action. The long term goal of this proposed research is to understand the molecular events underlying glucocorticoid-monokine interactions so that the perturbation in glucocorticoid action during endotoxic shock may possibly be reversed with therapeutic intervention. This, in turn, will lead to improved survival from a very serious and life-threatening clinical syndrome.
|Stith, R D; McCallum, R E; Hill, M R (1989) Effect of interleukin-6/interferon-beta 2 on glucocorticoid action in rat hepatoma cells. J Steroid Biochem 34:479-81|
|Stith, R D; McCallum, R E (1988) Failure of glucagon to induce hepatic phosphoenolpyruvate carboxykinase in endotoxic shock. Circ Shock 26:267-72|
|Hill, M R; Stith, R D; McCallum, R E (1988) Human recombinant IL-1 alters glucocorticoid receptor function in Reuber hepatoma cells. J Immunol 141:1522-8|
|Hill, M R; Stith, R D; McCallum, R E (1987) Monokines mediate decreased hepatic glucocorticoid binding in endotoxemia. J Leukoc Biol 41:236-41|
|Stith, R D; McCallum, R E (1986) General effect of endotoxin on glucocorticoid receptors in mammalian tissues. Circ Shock 18:301-9|
|Hill, M R; Stith, R D; McCallum, R E (1986) Interleukin 1: a regulatory role in glucocorticoid-regulated hepatic metabolism. J Immunol 137:858-62|
|Stith, R D; McCallum, R E (1985) Effects of aging and endotoxin on hepatic glucocorticoid action and glucose metabolism in mice. Mech Ageing Dev 30:73-8|