Prolactin and Estradiol are Epigenetic Modulators in Bovine Mammary Epithelial Cells during Staphylococcus aureus Infection.

Changes in the levels of reproductive hormones compromise the bovine innate immune response (IIR). Changes in 17β-estradiol (E2) and prolactin (bPRL) levels affect the IIR of bovine mammary epithelial cells (bMECs), the target tissue of these hormones. In this work, we explored the effect of the combined hormones on bMEC IIR during Staphylococcus aureus infection, and if they can modulate epigenetic marks. By gentamicin protection assays, we determined that combined hormones (bPRL (5 ng/mL) and E2 (50 pg/mL)] decrease S. aureus internalization into bMECs (~50%), which was associated with a reduction in integrin α5β1 membrane abundance (MA) (~80%) determined by flow cytometry. Additionally, combined hormones increased Toll-like receptor 2 (TLR2) MA (25%). By RT-qPCR, we showed that combined hormones induce the expression of pro- and anti-inflammatory cytokine genes, as well as up-regulate antimicrobial peptide gene expression. The combined hormones induced H3K9Ac at 12 h of treatment, which coincides with the reduction in histone deacetylase (HDAC, 15%) activity. In addition, hormones increased the H3K9me2 mark at 12 h, which correlates with a reduction in the expression of KDM4A. In conclusion, bPRL and E2 modulate the IIR of bMECs, an effect that can be related to the regulation of histone H3 modifications such as H3K9Ac and H3K9me2.