Epigenetic Regulation of the Innate Immune Response to LPS in Cattle

Epigenetic regulation of the immune response has important implications for the initiation of inflammation and development of disease. We hypothesised that epigenetic mechanisms regulate immune genes affecting the immune response in cattle. Peripheral blood mononuclear cells (PBMCs) from 5 healthy calves were treated with the histone deacetylase inhibitor, trichostatin A (TSA) (1μM) for 5 hours or the methylation inhibitor 5-Aza-2′-deoxycytidine (AZA) (2μM) for 72 hours and/or stimulated with LPS (1μg/ml) 4 hours before harvesting. To examine the epigenetic response to LPS treatment, genes encoding HDACs and DNMTs were analysed by qRT-PCR. HDAC6 and HDAC7 expression was significantly down regulated in response to LPS, as was that of DNMT3a (P≤0.05). To examine the effect of inhibiting histone deacetylation and DNA methylation on innate immune gene expression, candidate cytokine genes were analysed by qRT-PCR. Preliminary results show decreased expression of TNF, IFNG and IL2 (P≤0.05) when treated with TSA and LPS compared to LPS treatment alone. The expression pattern for IL1β followed the opposite trend; with TSA causing further increased expression. These preliminary results suggest that LPS treatment affects the expression of genes that encode enzymes important in the regulation of epigenetic processes. It also indicates that bovine proinflammatory immune gene expression is epigenetically regulated.