Dietary vitamin E modulation of cytokine production by splenocytes and thymocytes from alcohol-fed mice

Vitamin E supplementation does not prevent ethanol-reduced hepatic retinoic acid levels in rats

Chronic, excessive ethanol intake can increase retinoic acid (RA) catabolism by inducing cytochrome P450 2E1 (CYP2E1). Vitamin E (VE) is an antioxidant implicated in CYP2E1 inhibition. In the current study, we hypothesized that VE supplementation inhibits CYP2E1 and decreases RA catabolism, thereby preventing ethanol-induced hepatocyte hyperproliferation. For 1 month, 4 groups of Sprague-Dawley rats were fed a Lieber-DeCarli liquid ethanol (36% of the total energy) diet as follows: either ethanol alone (Alc group) or ethanol in combination with 0.1 mg/kg body weight of all-trans-RA (Alc + RA group), 2 mg/kg body weight of VE (Alc + VE group), or both together (Alc + RA + VE group). Control rats were pair-fed a liquid diet with an isocaloric amount of maltodextrin instead of ethanol. The ethanol-fed groups had 3-fold higher hepatic CYP2E1 levels, 50% lower hepatic RA levels, and significantly increased hepatocyte proliferation when compared with the controls. The ethanol-fed rats given VE had more than 4-fold higher hepatic VE concentrations than the ethanol-fed rats without VE, but this did not prevent ethanol induction of CYP2E1, lower hepatic retinoid levels, or hepatocellular hyperproliferation. Furthermore, VE supplementation could not prevent RA catabolism in liver microsomal fractions of the ethanol-fed rats in vitro. These results show that VE supplementation can neither inhibit ethanol-induced changes in RA catabolism nor prevent ethanol-induced hepatocyte hyperproliferation in the rat liver.

Prooxidant diet provides protection during murine infection with Toxoplasma gondii

Toxoplasmosis, particularly toxoplasmic encephalitis, has emerged as a major cause of morbidity and mortality in patients with acquired immunodeficiency syndrome. Patients infected with human immunodeficiency virus typically experience chronic oxidative stress, and concurrent infection with the intracellular parasite Toxoplasma gondii would be expected to further exacerbate this condition. The present study was conducted to determine whether vitamin E and selenium supplementation might be beneficial in a murine model of toxoplasmosis. To investigate the effect of these antioxidants on the severity of parasitic infection. Swiss Webster (SW) or C57Bl/6J mice infected with oocysts of the ME49 strain of T. gondii were maintained on diets containing no vitamin E or selenium, no vitamin E and 8 ppm selenium, 400 IU/kg vitamin E plus 8 ppm selenium, or vitamin E and selenium at the levels present in standard rodent chow (16 IU/kg and 0.2 ppm, respectively). The results of the study showed that increased dietary supplementation with vitamin E and selenium resulted in trends toward increased tissue cyst number, tissue pathology, and weight loss during infection. In contrast, both resistant SW and susceptible C57Bl/6J mice fed a deficient diet (complete absence of vitamin E and selenium) showed the lowest mean numbers of tissue cysts and very little evidence of tissue pathology during chronic infection.

Nutritional and metabolic effects of alcoholism: their relationship with alcoholic liver disease

Excessive alcohol ingestion disturbs the metabolism of most nutrients. Although alcohol can lead to severe hypoglycemia, alcoholics are usually glucose intolerant, probably due to a inhibition of glucose-stimulated insulin secretion. Ethanol intake also leads to negative nitrogen balance and an increased protein turnover. Alcohol also alters lipid metabolism, causing a profound inhibition of lipolysis. Looking for an association between alcohol intake, nutrition, and alcoholic liver disease, we have observed a higher prevalence of subclinical histologic liver damage among obese alcoholics. Multivariate analysis in a large group of alcoholics has shown that obesity is an independent predictor of alcoholic liver disease. Other authors have reported that alcoholics with a history of obesity have a two to three times higher risk of having alcoholic liver disease than non-obese alcoholics. The possible explanation for this association is that the microsomal system, which plays an important pathogenic role in alcoholic liver disease, is induced in non-alcoholic obese subjects and alcoholics. Also, peripheral blood monocyte cells of obese alcoholics produce higher levels of interleukin-1, a cytokine that can contribute to liver damage. The ingestion of polyunsaturated fatty acids can also increase the damaging effects of alcohol on the liver, as has been demonstrated in rats subjected to continuous intragastric infusion of alcohol. Observations in human alcoholics have shown that liver damage is associated with a higher ratio of C:18:1/C:18:0 and a lower ratio of C:22:4/C:18:2 in liver lipids, consistent with an induction of delta 9 desaturase and an increased peroxidation of C:22:4.

Effects of prenatal alcohol and pair feeding on lipopolysaccharide-induced secretion of TNF-alpha and corticosterone

Fetal alcohol exposure (FAE) produces profound alterations in immunological and neuroendocrine functions. The present study examined the effects of FAE on the secretion of tumor necrosis factor (TNF-alpha) and corticosterone following administration of lipopolysaccharide (LPS) in normal (N) adult rats, in adult offspring of dams fed a liquid diet supplemented with ethanol (E), and in pair-fed control offspring (P). LPS-induced TNF-alpha secretion was not affected by either gender or prenatal treatment. In contrast, LPS-induced corticosterone secretion was significantly greater in female than in male rats, and at 60-min post-LPS was significantly higher in E and P, compared to N females. Ovariectomy significantly inhibited LPS-induced TNF-alpha secretion in E, but not in P and N, rats and chronic replacement with 17-beta-estradiol markedly inhibited TNF-alpha secretion in ovariectomized E and N, but not in P, rats. In contrast, ovariectomy reduced the effects of LPS on corticosterone secretion in all groups, and chronic replacement with 17-beta-estradiol reversed this effect. These findings indicate that LPS-induced secretion of corticosterone, but not TNF-alpha, is affected by prenatal manipulations and by gender. In addition, alterations in the hormonal environment in females modulate LPS-induced corticosterone secretion in all prenatal treatment groups, but differentially influence TNF-alpha secretion in rats exposed to alcohol, restricted feeding, or normal diets in utero.

Immunomodulation by pycnogenol in retrovirus-infected or ethanol-fed mice

Pycnogenol is a commercial mixture of bioflavonoids that exhibits antioxidative activity. The effects of dietary pycnogenol on immune dysfunction in normal mice as well as those fed ethanol or infected with the LP-BM5 murine retrovirus were determined. The ethanol consumption and retrovirus infection caused abnormalities in the function and/or structure of a broad array of cells involved in humoral and cellular immunity. Pycnogenol enhanced in vitro IL-2 production by mitogen-stimulated splenocytes if its production was suppressed in ethanol-fed or retrovirus-infected mice. Mitogenesis of splenocytes did not show a significant change in mice treated with pycnogenol. It reduced the elevated levels of interleukin-6 produced in vitro by cells from retrovirus infected mice and IL-10 secreted by spleen cells from mice consuming ethanol. Natural killer cell cytotoxicity was increased with pycnogenol treatment.

Ethanol, immune responses, and murine AIDS: the role of vitamin E as an immunostimulant and antioxidant

Excessive alcohol consumption is a major health problem in the United States. Prolonged consumption of alcohol results in alterations of immune responses, ultimately manifested by increasing susceptibility to infectious agents. Such changes can be due to the direct effects of alcohol or its metabolites on immune cells, as well as to nutritional deficiency, oxidative stress, and neutrophil dysfunctions. This ETOH-induced immunosuppression could be a potential cofactor in the progression to AIDS. As vitamin E supplementation has been associated with enhancement of immune response and improvement of host defense, it may provide a useful therapeutic approach for treatment of alcoholics to improve host defense. This article is a review of alcohol-related immunosuppression as a possible cofactor in the development of AIDS, and vitamin E-related immunoenhancing roles in animals and humans, showing why vitamin E supplementation could be used as a useful adjunct agent in alcoholics' treatment. Since there is little information available regarding nutritional therapy with alcohol users, our purpose is to provide evidence from animal models of the potential therapeutic role of vitamin E supplementation in the treatment of alcoholics.