Effect of ethanol on B cell expression of major histocompatibility class II proteins in immunized mice

Morphine suppresses MHC-II expression on circulating B lymphocytes via activation of the HPA

Morphine has been shown to alter gene expression of the major histocompatibility complex, class II (MHC-II) in circulating rat immunocytes. Here, we demonstrate that a single morphine injection (10 mg/kg) reduces basal MHC-II protein expression on circulating B lymphocytes by 33%, while also impairing the ability of B lymphocytes to increase MHC-II upon interleukin-4 induction. As these data implicate opioids in the regulation of antigen presentation, studies were undertaken to examine the potential mechanisms through which morphine exerts this suppressive effect. Central injection studies utilized Tyr-D-Ala-Gly-(me) Phe-Gly-ol (DAMGO), an opioid receptor agonist, which mimicked morphine's effect on MHC-II, while D-Phe-Cys_Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP) pretreatment, prior to morphine, blocked the suppression of MHC-II. As central opioid receptor activation results in the activation of the hypothalamic-pituitary-adrenal axis, thereby, signaling increased circulating corticosterone levels, we examined whether MHC-II expression was suppressed after incubation with corticosterone at concentrations similar to those observed after morphine. Interestingly, corticosterone dramatically decreased basal MHC-II (88%) expression while completely preventing the induction of MHC-II. Additionally, MHC-II suppression was absent in morphine-treated adrenalectomized animals. Since prolonged morphine exposure has previously been shown to result in tolerance to both the steroidogenic and immunosuppressive effects of morphine, the effect of prolonged morphine exposure on MHC-II was also examined. Interestingly, MHC-II expression is no longer suppressed after chronic morphine, while morphine withdrawal results in both a renewed increase in circulating corticosterone levels and a renewed suppression of MHC-II in previously tolerant animals. Taken together, these data strongly implicate corticosterone in mediating the suppressive effects of morphine on circulating B-lymphocyte MHC-II expression.

Ethyl pyruvate ameliorates acute alcohol-induced liver injury and inflammation in mice

Ethyl pyruvate dissolved in a calcium-containing balanced salt solution--Ringer's ethyl pyruvate solution (REPS)--ameliorates ileal mucosal hyperpermeability and decreases the expression of several proinflammatory genes when it is used instead of Ringer's lactate solution (RLS) to resuscitate mice from hemorrhagic shock. Herein, we sought to determine whether delayed treatment with REPS would be beneficial in a murine model of acute alcoholic liver injury associated with binge drinking. Mice were gavaged with 3 doses of ethanol (5 g/kg each dose) over a 12-hour period and then randomized to treatment with 3 intraperitoneal doses of REPS or RLS over 12 hours. Compared with sham-treated controls not subjected to alcohol intoxication, RLS-treated mice demonstrated histologic evidence of fatty change and piecemeal necrosis of hepatocytes in the liver, as well as a significant increase in the plasma concentration of alanine aminotransferase. Biochemical changes induced by alcohol administration included increased hepatic lipid peroxidation, nuclear factor-kappaB activation, and tumor necrosis factor-alpha messenger RNA expression. All of these alcohol-induced effects were ameliorated by treatment with REPS instead of RLS. These data support the view that treatment with REPS ameliorates the hepatic inflammatory response and decreases hepatocellular injury in mice subjected to acute alcohol intoxication.

Diminished proliferation of B blast cell in response to cytokines in ethanol-consuming mice

We and others have demonstrated that ethanol suppresses the antibody response in humans and animals. The purpose of this study was to determine whether ethanol affects cytokine-induced proliferative responses of splenic B blast cells, and whether the decreased response was due to an imbalance of the cytokine activity. Thus, the ability of spleen cells from individual ethanol-diet-fed C57BL/6 mice to proliferate and produce cytokines was determined. The ability of anti-IgM monoclonal antibodies (mAb)-activated splenic B blast cells in response to mouse recombinant IL-2 (rIL-2) or rIL-4 was also assessed. A thymidine incorporation assay was used to determine cell proliferation, and the conventional bioassays for cytokine-dependent cell proliferation were used for determining the bioactivity of cytokines. Data were analyzed with general linear model procedure. Our results showed that ethanol weakened the proliferative response of B cells in response to mitogen as well as to mouse rIL-2 and rIL-4. The decreased B cell responses may result from an increase in the production of IL-4 by helper T cells. Finally, in the presence of excessive dose of rIL-4, the proliferative responses of B blast cells from all three groups of mice were diminished (p<0.01). Thus, our data clearly indicated that the diminished B cell proliferation in ethanol-consuming mice was due in part to an excessive amount of IL-4 produced and an inability of the B cell to interact properly with IL-4 that was secreted by helper T cells. The results should extend our basic understanding of the mechanism by which chronic alcoholism impairs the interactions and interdependence of T- and B-cell immune functions.