Effect of fumonisins on macrophage immune functions and gene expression of cytokines in broilers

Fumonisin (FB1), a mycotoxin, is produced by Fusarium moniliforme and F. proliferatum. A prevalence survey in Taiwan by our laboratory showed that there was a contamination rate of 40% in domestic animal feeds, and the average contaminated level was 4.5 mg/kg. Ninety-six birds were allotted into four treatments fed with diets containing 0 (control), 5, 10, or 15 mg/kg of FB 1 for three weeks. The results showed that the growth performance was not influenced by the FB 1 challenge, but relative bursa weight was significantly decreased. The activity of serum aspartate aminotransferase, and the serum levels of albumin and cholesterol were significantly elevated by the FB 1 challenges. When broilers were stimulated with injection of lipopolysaccharides, mRNA abundance (determined by semi-quantitative RT-PCR) interleukin-1 beta (IL-1 beta), IL-2, interferon-alpha (IFN-alpha), IFN-gamma, and inducible nitric oxide synthase (iNOS) reached a plateau at 3 h, and declined at 6 h. A FB 1 challenge for three weeks increased cytokine mRNA abundance in broilers. The results also showed that 15 mg FB 1 per kg feed significantly inhibited the expression of IL-1 beta, IL-2, IFN-alpha, IFN-gamma, but had no effect on iNOS. The macrophage functional profile was significantly changed under an exposure of 15 mg FB 1 per kg for three weeks. Taken together, our results suggest that FB 1 up to 15 mg/kg does not affect growth performance, but impairs some parameters of blood biochemistry and the immunocompetence in broilers.