Reduction of perforin, granzyme B, and cytokine interferon gamma by ethanol in male Fischer 344 rats

Abstract

Background: Chronic alcohol consumption can impair the immune system and predispose individuals to an increased risk of cancer and infection. Natural killer (NK) cells are the first line of defense against viral, bacterial, and fungal infections and play an important role in cellular resistance to malignancy and tumor metastasis. We have shown previously that ethanol administration suppresses NK cell cytolytic activity in male Fischer rats. This study analyzed the effects of ethanol on perforin, granzyme B, and the cytokine interferon (IFN)-gamma, factors that modulate NK cell cytolytic activity, to understand the molecular mechanism involved in ethanol's suppression of NK cell activity.

Methods: A group of male Fischer rats was fed an ethanol-containing diet (8.7% v/v), whereas a control group was pair-fed an isocaloric diet. At the end of 2 weeks, animals were decapitated, and spleen tissues were immediately removed and used for analysis of NK cell cytolytic activity, perforin, granzyme B, and IFN-gamma messenger RNA (mRNA) or protein levels. The mRNA levels of perforin, granzyme B, and IFN-gamma were evaluated by quantitative real-time polymerase chain reaction, and protein levels of these factors were analyzed by Western blot, enzyme-linked immunosorbent assay, or enzymatic activity assay.

Results: Ethanol reduced the NK cell cytolytic activity and decreased the mRNA expression of perforin, granzyme B, and IFN-gamma in ethanol-fed animals when compared with pair-fed animals. Ethanol also significantly reduced the protein levels of perforin and IFN-gamma and the enzyme activity of granzyme B in alcohol-fed animals as compared with pair-fed animals.

Conclusions: These data suggest that chronic ethanol consumption may suppress NK cell cytolytic activity in male Fischer rats by decreasing the production, activity, or both of granzyme B, perforin, and IFN-gamma.