Zinc is an essential trace element that plays an important role in the metabolism and also the immune system. It is a co-factor of more than 300 enzymes some of which are active in immune cells. Zinc deficiency causes immunodeficiency and increased morbidity after infection. Zinc is often used as a food additive to improve the health status and performance of weaned piglets. In an earlier study it was found higher levels of shedding of Salmonella Typhimurium and lower frequencies of T cells in the ileal lymph nodes of piglets after feeding a high dosage of zinc as zinc oxide for six weeks. Suppressor of cytokine signaling (SOCS) proteins play an important role in the regulation of the immune response by inhibiting cytokines. There were 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.
It was detected a 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. Thus a high dosage of zinc seems to be beneficial only shortly after weaning, while high levels of zinc supplementation over a long period seems to promote immune modulation by S. Typhimurium to evade the host’s immune response. Hence, feeding a high dosage of zinc oxide over a period of 6 weeks affects suppressor of cytokine gene expression and thereby potentially modulates the immune response.
Schulte, J. N., Brockmann, G. A., & Kreuzer-Redmer, S. (2016). Feeding a high dosage of zinc oxide affects suppressor of cytokine gene expression in Salmonella Typhimurium infected piglets. Veterinary Immunology and Immunopathology, 178, 10-13.http://dx.doi.org/10.1016/j.vetimm.2016.06.009