Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 11, 2010
Publication Date: March 15, 2010
Citation: Nelson, C.D., Reinhardt, T.A., Beitz, D.C., Lippolis, J.D. 2010. 1,25-Dihydroxyvitamin D3 Enhances Innate Immune Responses of Bovine Mammary Epithelial Cells that are Triggered by Toll-like Receptor Signaling [abstract]. Midwest Branch of the American Dairy Science Association. p. 30. Technical Abstract: Recently, 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) has been found to play an important role in the bovine innate immune response. 1,25(OH)2D3 is the active vitamin D metabolite and is produced from the major circulating metabolite, 25-hydroxyvitamin D3, by the enzyme 1alpha-hydroxylase (1alpha-OHase). Bovine monocytes express 1alpha-OHase in response to toll-like receptor (TLR) recognition of bacteria and we have evidence that 1alpha-OHase is expressed in mammary tissue during mastitis. Production of 1,25(OH)2D3 by 1alpha-OHase in activated monocytes amplifies the expression of inducible nitric oxide synthase (iNOS) and the chemokine RANTES. Mammary epithelial cells (MEC) have been shown to express iNOS, RANTES, and S100 calcium binding protein A12 (S100 A12) in response to TLR signaling, but the effects of 1,25(OH)2D3 on expression of those genes in MEC were not known. The objective of this experiment was to determine the effects of 1,25(OH)2D3 and lipopolysaccharide (LPS) on iNOS, RANTES, and S100 A12 gene expression in bovine MEC. Primary cultures of MEC were derived from mammary biopsies of Holstein cows in mid-lactation. To determine the effects of 1,25(OH)2D3 and LPS on MEC, cultures were treated with 0, 0.1, 1, and 10 nM 1,25(OH)2D3 along with 0 or 1 ug/mL lipopolysaccharide (LPS) with six replicates for each treatment. Gene expression was measured by real-time PCR. In MEC stimulated with LPS, expression of iNOS and S100 A12 increased with 1,25(OH)2D3 dose (P < 0.05). In the absence of LPS the effects of 1,25(OH)2D3 on iNOS and S100 A12 expression were minimal in comparison to the combined effects of LPS and 1,25(OH)2D3. RANTES gene expression in MEC did not increase with 1,25(OH)2D3 treatment as previously observed in activated monocytes, but did increase significantly with LPS treatment alone (P < 0.05). In conclusion, iNOS and S100 A12 expression induced by toll-like receptor signaling in mammary epithelial cells is up-regulated by 1,25(OH)2D3. Production of 1,25(OH)2D3 by 1alpha-OHase in inflamed mammary tissue, then, may increase iNOS and S100 A12 expression in MEC during mastitis.