Profile of chicken cytokines induced by lipopolysaccharide is modulated by dietary alpha-tocopheryl acetate

Previously, we found that 25 to 50 IU/kg of dietary vitamin E (VE) had very different immunoregulatory effects than high VE levels (200 IU/kg), and we hypothesized that this difference was due to different cytokine profiles. Chicks were fed 0, 30, or 200 IU/kg supplemental VE and percentages of CD4+CD8-, CD4-CD8+, CD4+CD8+, and CD4-CD8- lymphocytes, and the ratio of CD4+/CD8+ lymphocytes was determined. The expression of chicken splenic interleukin-1beta (IL-1beta), myelomonocytic growth factor (MGF), interferon (IFN-gamma), and transforming growth factor-beta (TGFbeta) mRNA was determined by reverse transcription (RT)-PCR after intravenous injection of lipopolysaccharide (LPS). Due to a tendency for increased CD4-CD8+ lymphocytes at 30 IU/kg VE (P=0.072), the CD4+/CD8+ ratio was significantly lower for 30 IU/kg VE compared with 0 IU/kg VE (P=0.041). The VE dose of 200 IU/kg decreased the constitutive (prior to LPS) expression of TGFbeta. The LPS caused an increase in IL-1beta, MGF, and IFNgamma expression at all VE concentrations and had no effect on IL-2 and TGFbeta mRNA expression. Dietary VE decreased MGF mRNA (P=0.049) in a dose-dependent manner but had no effect on the expression of other cytokines. The decreased expression of MGF could explain the immunomodulatory effect of VE in inflammation.