Profile of chicken cytokines induced by lipopolysaccharide is modulated by dietary α-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 (IFNgamma), 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.