Browsing by Subject "Interferon gamma"

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Effect of low ethanol concentrations on the production and stability of Interferon gamma
(2008) Sauter, Senja; Bode, Christiane
Alcohol is known to modulate the immune system in a complex manner. The effects of alcohol on immune responses vary with acute and chronic exposure as well as depending on the history of alcohol consumption and the blood level of alcohol. The presence or absence of alcohol can affect the cytokine cascade in complex ways. In the current study the immunmodulatory capability of an acute, moderate (1 ?) to high amount (3 ?) of alcohol was tested on isolated Peripheral Blood Mononuclear Cells production of several proinflammatory and antiinflammatory cytokines after incubation for 12 to 72 hours. The most affected cytokine in our model system of isolated human PBMC treated with two different ethanol concentrations was IFN-γ. Its concentration decreased in a highly significant manner in PHA- as well as in LPS-stimulated PBMC when treated with 66 mM ethanol and in a significant manner in PHA-activated PBMC when treated with 22 mM ethanol. The fact that ethanol negatively affects IFN-γ production is supported by several in vivo and in vitro studies by Wagner et al., 1992, Chen et al., 1993, Laso et al., 1997 Waltenbaugh et al., 1998, Starkenburg et al., 2001, Szabo et al., 2001, Dokur et al., 2003. The reduced IFN-γ level observed might be a key factor in explaining comprised immunity seen after chronic alcohol abuse, since together with IL-12, IFN-γ is crucial for the innate and adaptive immune response to viral and bacterial infection (Vicente-Gutierrez et al., 1991, Windle et al., 1993, Szabo 1997, Szabo et al., 1999). As seen in isolated human Peripheral Blood Mononuclear Cells IFN-γ production by IL-12 stimulated NK-92 cells is significantly reduced in the presence of ethanol. However, this decrease did not correlate with decreased phosphorylation and nuclear translocation of STAT4, a central regulator of IFN-γ gene expression. These results indicated that acute alcohol treatment in vitro did not affect intracellular pathways leading to IFN-γ gene expression. These findings paralleled results indicating that the amount of mRNA for IFN-γ synthesis in NK-92 cells is not affected by the applied ethanol concentrations as well. Additionally it was shown within the current work, that the reduced IFN-γ production by NK-92 cells in the presence of ethanol might not be explained by an intracellular accumulation of the IFN-γ protein. The inhibitory action of ethanol on IFN-γ may rather be caused by posttranslational modification once IFN-γ is released by NK-92 cells, since the addition of recombinant human IFN-γ to the cell culture supernatants of ethanol-treated cells led to a decline in the amount of IFN-γ concentration. We therefore hypothesized that ethanol may cause the release of either an IFN-γ-binding or IFN-γ-degrading protein. An increase in soluble IFN-γ receptor as a result of ethanol treatment was not observed. But the addition of mixture of 5 commercially available protease inhibitors counteracted the effect of ethanol treatment, giving us a first hint of IFN-γ-modulatory mechanism, where IFN-γ released by NK-92 cells may be disintegrated by a protease released as consequence of ethanol incubation. To our best knowledge we are the first to demonstrate a posttranslational modification of IFN-γ as a consequence of ethanol incubation. In summary, the present results support the inhibitory role of ethanol on IFN-γ, but are too preliminary to explain the underlying immunmodulatory effect.
Geschlechtsspezifische Unterschiede in der Entstehung von alkoholbedingten Lebererkrankungen
(2010) Wagnerberger, Sabine; Bode, Christiane
Women are assumed to have a higher susceptibility to alcohol-induced liver disease (ALD) than men. Gender-related differences in food preference were described in previous studies for several populations. As certain micronutrients are reported to take influence on the development of ALD in animal experiments, the hypothesis of the present retrospective cross-sectional study was that gender-dependent (micro-) nutrient intake in patients with ALD may cause the higher susceptibility of women to this disease. In 210 patients (male: 158, female: 52) with different stages of ALD (ALD1: mild stage of liver damage; ALD2: moderately severe changes of the liver with signs of hepatic inflammation; ALD3: severely impaired liver function) and in 336 controls (male: 208, female: 128), nutrient intake was determined by a computer-guided diet history and related to the severity of ALD in dependence on the sex of the patients. No significant differences between males and females with ALD were calculated for the intake (per kg body/day) of protein, carbohydrates, fat, and the intake (per kg body/day) of most micronutrients. In females with ALD, higher intake was found for vitamin C (ALD3), calcium (ALD2), iron (ALD1 and ALD2), and zinc (ALD1), but the consumption of none of these micronutrients seems to contribute to a higher susceptibility to ALD in females. In the present study, a higher activity of ?liver-specific? enzymes and a higher DeRitis quotient was measured in female patients with ALD despite equal or lower amounts of consumed alcohol. This may indicate a higher susceptibility to the development of ALD in women. However, the data of calculated daily macro- and micronutrient intake do not suggest any explicit influence of gender-specific nutrition in the development of ALD. In a chronic setting of alcohol intake, women and female rodents are more susceptible to alcohol-induced liver disease than men and male mice. Starting from this background, the purpose of the present study was to determine if female mice are also more susceptible to acute alcohol-induced steatosis than male mice and to investigate whether this is due to alterations in hepatic lipid export. Male and female C57/Bl6-mice received one single dose of ethanol (6 g/kg) or isocaloric maltose-dextrin solution (control) intragastrically. Hepatic triglycerides, lipid accumulation, mRNA expression of microsomal triglyceride transfer protein (MTP) and apolipoprotein (Apo) B, as well as MTP activity were measured 12, 24, and 48 h after alcohol intake. In both genders, acute alcohol ingestion markedly increased hepatic lipid and triglyceride levels; however, total lipid accumulation was ~2-fold higher and more persistent in livers of female than in male mice. Fourty-eight h after ethanol treatment hepatic triglyceride concentrations in male and female ethanol-treated mice were similar to those of controls. MTP activity was significantly increased only in male mice 12 h after ethanol ingestion; whereas expression of MTP mRNA was significantly reduced in female alcohol-treated animals compared to controls at this timepoint. Expression of ApoB was also reduced only in livers of female mice after 12 h; however, differences did not reach level of significance. The results of the present study suggest that the markedly more pronounced and more prolonged susceptibility to acute alcohol-induced liver steatosis of female mice results at least partly from a gender-specific regulation of hepatic lipid export. In our experiments, the selective estrogen recepor modulator (SERM) toremifen did not protect against alcohol-induced hepatic lipid accumulation. The liver plays an important role not only in the metabolism of ethanol but also in the immune system. Lymphatic NK cells are present at an unusually high frequency among liver-resident lymphocytes (30-50 %). By producing the pro-inflammatoric and anti-fibrotic cytokine IFN-g NK cells are involved in the development of liver diseases. Results of studies of our own working group indicate a decrease of IL-12-induced IFN-g production in NK-92 cells after treatment with ethanol for 6 h. The aim of the present study was to investigate whether male (testosterone) or female (estrogen, progesterone, FSH, LH) sex hormones influence the ethanol-induced immunosuppression in NK-92 cells. Therefore, NK-92 cells were incubated with different sex hormones for 19 h and were subsequently treated with ethanol (1-3 ?) and sex hormones for 18 h. Concentrations of IFN-g were determined by ELISA. According to previous studies ethanol treatment resulted in a significant decrease of released IFN-g in comparison to NK-92 cells that were not incubated with ethanol. However, treatment with male and female sex hormones did not affect IFN-g release in NK-92 cells. The results of the present study suggest that solely ethanol treatment but not incubation with sex hormones has an immun modulating effect on NK-92 cells.