Secondary metabolites of Aspergillus exert immunobiological effects on human monocytes

This project focused on the effects of aflatoxin B1 (AFB1), a food-contaminating mycotoxin produced by fungi, genus Aspergillus, on the release and genetic expression of some important cytokines, i.e., (interleukin-1 alpha (IL-1 alpha), IL-6, tumor necrosis factor-alpha (TNF alpha)) by human monocytes. Monocytes, preincubated for different time periods with concentrations of AFB1 ranging from 0.01 to 1.0 pg/mL, were then activated with bacterial lipopolysaccharide. Cytokine levels were measured by immunoassay and mRNA by cDNA amplification. Pretreatment of monocytes with AFB1 resulted in a decrease in IL-1, IL-6 and TNF alpha release already at a concentration of 0.05 pg/mL. The gene expression of the cytokines considered was drastically affected by treatment with AFB1. In fact, AFB1 completely blocked the transcription of IL-1 alpha, IL-6 and TNF alpha mRNAs, while it did not affect beta-actin mRNA at the concentrations used. It therefore appears that AFB1 exerts its effect on cytokine release through selective inhibition of specific mRNA, without affecting general protein synthesis.