Altered monocyte functions are major contributors to the development of alcohol induced immune and metabolic abnormalities. Ethanol-induced elevated M0 Prostaglandin E2 (PGE2) is the mediator of many alcohol related M0 and T lymphocyte defects. Decreased production of inflammatory monokines, such as TNFalpha, has been reported in rats after acute ethanol uptake. Our data on human M0 indicate that single in vitro ethanol treatment decreases the production of biologically active M0 TNFalpha and IL-6 with concomitant increase in the production of inhibitory M0 mediators, such as PGE2 and Transforming Growth Factorbeta (TGFbeta). High PGE2 levels downregulate Mo TNFalpha production via elevated cyclic AMP (cAMP). However our data indicate the existence of a PGE2-independent pathway for monokine regulation by ethanol. Ethanol has been shown to increase cAMP levels in lymphoid cells. Increases in M0 cAMP level has the potential to regulate bioactive TNFalpha production and gene expression. Therefore, our hypothesis is that ethanol can regulate the production of monokines, particularly that of TNFalpha, via a cAMP dependent pathway by directly increasing M0 cAMP levels. furthermore, the differential effect of chronic ethanol treatment on M0 TNFalpha production may be related to alcohol induced repetitive PGE2 elevations which can desensitize M0 to PGE2 mediated downregulation of TNFalpha production during chronic alcohol treatment. Consequently, we propose to study the involvement of cAMP in the mechanism by which acute and chronic ethanol treatment alters the production of MO TNFalpha, IL-6 and TGFbeta at the levels of mRNA and bioactivity. Changes in the intracellular cAMP following ethanol exposure as well as the effect of cAMP agonists and antagonists on the ethanol induced alterations of monokine production will be assessed. The role of PGE2 in ethanol induced monokine and cAMP alterations will also be investigated. In addition to affecting cAMP signal transduction, ethanol can also amplify signal transduction via Ca++ mobilization. Intracellular Ca++ levels were shown to rapidly increase in response to ethanol in rat M0. Ca++ increase results in M0 PGE2 production which has the potential for regulation of monokine production. Consequently, we hypothesize that ethanol related increases in intracellular Ca++ levels in M0 contribute to altered M0 responses after alcohol treatment. Therefore, we propose to study the ethanol induced changes in the level of intracellular Ca++ and correlate them with its effect on M0 PGE2 production. Alcohol induced intracellular Ca++ levels will be evaluated in the individual M0 on the Attofluor.
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| Szabo, G; Mandrekar, P; Catalano, D (1995) Inhibition of superantigen-induced T cell proliferation and monocyte IL-1 beta, TNF-alpha, and IL-6 production by acute ethanol treatment. J Leukoc Biol 58:342-50 |
