Immunomodulation by fungal toxins

Abstract

The availability of immunotoxicity data for fungal toxins varies considerably for different toxins. The following is a comprehensive review of the most recent literature on the immunotoxicity of aflatoxins, fumonisins, gliotoxin, ochratoxins, patulin, and trichothecenes. Aflatoxin is an immunomodulating agent that acts primarily on cell-mediated immunity and phagocytic cell function. In addition to further characterization of aflatoxin-induced immunotoxicity in various species, some recent studies have focused on ameliorating the effects of aflatoxin by supplementing or amending the diet. The immunomodulatory effects of ochratoxins have also been considered for many years. Notably, recent studies have examined immune function in the offspring of rats and mice exposed to ochratoxin pre- and perinatally. Fumonisin toxicity has been characterized relatively recently in comparison to aflatoxin and ochratoxin, and fumonisin-induced immunotoxicity is an area of active research. As these studies progress, they may also clarify the role of sphingolipid metabolism in immune function. The most recent study of patulin immunotoxicity in mice indicates that exposure to levels found in foods and feeds would not likely result in immunotoxicity. Exposure to gliotoxin would most likely be by infection with gliotoxin-producing fungi. Although the toxin is immunosuppressive in vitro, the link between immunosuppression and the presence of gliotoxin in infected tissues in vivo has yet to be made. The trichothecenes can both suppress and stimulate immune function. By comparison, more information is available on the molecular events associated with trichothecene-induced immunomodulation than for any other fungal toxins. The molecular basis of immune function modulation by fungal toxins remains a frontier for future research.