Effect of Vanadium on TLR4 and TLR7 mRNA Expression in the Lymphoid Organs of Broilers

TLRs are important innate immune receptors. It has been found that vanadium can affect the immune function in broilers. However, vanadium action in the regulation of TLRs is unknown. A total of 420 one-day-old avian broilers were divided into six groups, and fed on a corn-soybean basal diet as control diet (vanadium 0.073 mg/kg) or the same diet supplemented with vanadium at the doses of 5, 15, 30, 45 and 60 mg/kg in the form of ammonium metavanadate. TLR4 and TLR7 mRNA expression in lymphoid organs of each group were studied by real time RT-PCR form. The results indicated that the TLR4 and TLR7 mRNA expression in thymus and TLR4 mRNA expression in bursa were down-regulated in the 60 mg/kg group. The TLR7 mRNA expression in bursa was down-regulated in 30 mg/kg, 45 mg/kg and 60 mg/kg groups, and up-regulated in the 5 mg/kg group. Also, the TLR4 and TLR7 mRNA expression in spleen was down-regulated in the 45 mg/kg and 60 mg/kg groups, and up-regulated in the 5 mg/kg group. The abovementioned results showed that dietary vanadium in excess of 30 mg/kg could down-regulate the TLR4 and TLR7 mRNA expression in lymphoid organs, which finally impaired innate immunity in broilers.