Effects of feed contaminant deoxynivalenol on plasma cytokines and mRNA expression of immune genes in the intestine of broiler chickens

Abstract

An experiment was conducted to investigate the individual and combined effects of dietary deoxynivalenol (DON) and a microbial feed additive on plasma cytokine level and on the expression of immune relevant genes in jejunal tissues of broilers. A total of 40 broiler chicks were obtained from a commercial hatchery and divided randomly into four groups (10 birds per group). Birds were reared in battery cages from one day old for 5 weeks. The dietary groups were 1) control birds fed basal diet; 2) DON group fed basal diet contaminated with 10 mg DON/ kg feed; 3) DON + Mycofix group fed basal diet contaminated with 10 mg DON/ kg feed and supplemented with a commercial feed additive, Mycofix® Select (MS) (2.5 kg/ton of feed); 4) Mycofix group fed basal diet supplemented with MS (2.5 kg/ton of feed). At 35 days, the plasma levels of tumor necrosis factor alpha (TNF-α) and interleukin 8 (IL-8) were quantified by ELISA test kits. Furthermore, the mRNA expression of TNF-α, IL-8, IL-1β, interferon gamma (IFNγ), transforming growth factor beta receptor I (TGFBR1) and nuclear factor kappa-light-chain-enhancer of activated B cells 1 (NF-κβ1) in jejunum were quantified by qRT-PCR. The results showed that the plasma TNF-α decreased in response to DON, while in combination with MS, the effect of DON was reduced. DON down-regulated the relative gene expression of IL-1β, TGFBR1 and IFN-γ, and addition of MS to the DON contaminated diet compensates these effects on IL-1β, TGFBR1 but not for IFN-γ. Furthermore, supplementation of MS to either DON contaminated or control diet up-regulated the mRNA expression of NF-κβ1. In conclusion, DON has the potential to provoke and modulate immunological reactions of broilers and subsequently could increase their susceptibility to disease. The additive seemed to have almost as much of an effect as DON, albeit on different genes.

Figure 1. The relative mRNA expression of immune genes in the jejunal tissues of broiler chickens at 35 days after feeding of experimental diets was quantified by qRT-PCR.

The mRNA expression of controls and birds fed with DON or DON+Mycofix or Mycofix was compared for (A) TNF-α and IL-8, (B) IL-1β and TGFBR1, as well as for (C) IFN-γ and NF-κβ1. The relative gene expression for each gene was calculated relative to the gene expression of the control group. Bars show the means and standard errors of means (SEM). GAPDH was chosen as a reference gene having the same relative expression mean in the control as in the treated groups. Values are the means of 5 birds. The difference in relative expression of immune gene between birds fed experimental diets and birds fed control basal diet was assessed by Student's t-test and comparisons were considered significantly different at P<0.05 (*), P<0.01 (**), and P<0.001 (***) or as a trend for a difference at P<0.1 (^#).