Selenium and Polysaccharides of Atractylodes macrocephala Koidz Play Different Roles in Improving the Immune Response Induced by Heat Stress in Chickens.

The aim of the present study was to investigate the effect of acute heat stress (HS) on the chicken immune response and to examine the role of selenium (Se) and the polysaccharides of Atractylodes macrocephala Koidz (PAMK) in immune regulation in the chicken immune system. Two hundred chickens were randomly divided into two groups: the HS group and the control (Con) group. These chickens were treated with Se (0.3 mg/kg), PAMK (200 mg/kg) alone, and a combination of Se (0.3 mg/kg) and PAMK (200 mg/kg). The cytokines; antioxidative enzymes; and HSP60, HSP70, and HSP90 levels were examined in chicken immune organs. The results indicated that HS-induced immune dysfunction included increased levels of TNF-α, IFN-γ, IL-2, IL-4, HSP60, HSP70, HSP90, and malondialdehyde (MDA) as well as decreased levels of glutathione peroxidase (GPx) and superoxide dismutase (SOD) in immune organs (P < 0.05). Among the affected organs, the bursa of Fabricius was one primary target of HS. The immune dysfunction induced by HS was alleviated (P < 0.05 or not) by treatment with Se and PAMK in different immune organs. However, Se only regulated the expression of TNF-α and IFN-γ, and PAMK influenced more cytokines in immune organs. The results showed that Se specifically regulated the TNF-α and IFN-γ pathways. Therefore, Se and PAMK played different roles in improving the immune response in HS chicken.