Prenatal Exposure of Rats to Staphylococcal Enterotoxin B Alters the Expression of Th1 and Th2 Cytokines via Decreased Methylation in the Spleen of Adult but not Neonatal Offspring

Background: The methylation of IFN-gamma and IL-4 genes is regarded as an epigenetic regulation that maintains the Th1 or Th2 phenotype. Objective: To explore the influence of prenatal administration of the staphylococcal enterotoxin B (SEB) in pregnant rats, on the IFN-gamma or IL-4 expression in the offspring spleen. Methods: The SEB or PBS was administered intravenously to pregnant rats on the embryo-day 16. After normal delivery, the spleens from the fifth-day neonates and adult offspring were isolated under anesthesia. Quantitative PCR, western blot, ELISA and MeDIP-qPCR were applied to determine the levels of the splenic IFN-gamma or IL-4 mRNAs, their protein levels, and methylation status, respectively. Results: Prenatal administration of the SEB in pregnant rats decreased the levels of the splenic IFN-gamma and IL-4 proteins in neonates, but increased their mRNA levels. However, prenatal administration of the SEB significantly augmented both mRNA and protein levels of the IFN-gamma and IL-4 in the adult spleen. In addition, the prenatal SEB administration decreased the methylation of the splenic IFN-gamma and IL-4 in adult but not neonatal offspring. Conclusion: The prenatal administration of SEB in pregnant rats can cause a mixed Th1 and Th2 cytokines response in the offspring spleen, and alter the cytokine expression of the Th1 and Th2 via decreasing the methylation in adult but, not neonatal offspring spleen.