Feeding a high dosage of zinc oxide affects suppressor of cytokine gene expression in Salmonella Typhimurium infected piglets

Suppressor of cytokine signaling (SOCS) proteins play an important role in the regulation of the immune response by inhibiting cytokines. Here we investigated the effects of zinc oxide fed at three different dosages (LZN = 57 ppm, MZN = 167 ppm, HZN = 2425 ppm) to weaned piglets that were or were not orally infected with Salmonella enterica serovar Typhimurium DT 104. We detected higher expression of SOCS3 six days after weaning for all analyzed piglets, regardless of the infection or the zinc feeding, suggesting a stress induced immune response. Whereas, SOCS1 showed only higher transcript amounts in S. Typhimurium infected piglets, especially the LZN group. This might indicate an infection regulating effect of zinc oxide in the infection model. After 42 days of infection, the expression of SOCS2, SOCS4, and SOCS7 was increased only in animals fed the highest concentrations of zinc oxide, while non-infected piglets at the age of 56 days showed no regulation for these genes. The up-regulation of SOCS genes in the mesenteric lymph nodes of piglets fed a diet with a very high concentration of zinc over 6 weeks suggests that such treatments may impair the immune response.