Short communication: Effects of trans fatty acids on markers of inflammation in bovine mammary epithelial cells

Trans fatty acids (tFA) contribute to inflammation. The objective was to investigate the effects of tFA on mRNA expression of proinflammatory markers in cultured bovine mammary epithelial cells (MAC-T cell line). Bovine mammary epithelial cells were grown in Dulbecco's Modified Eagle Medium containing 10% fetal bovine serum. Cells were then subcultured in a medium lacking fetal bovine serum, to which incremental concentrations (up to 90 mu M) of elaidic acid (trans-9 C18:1) or linoleidic acid (trans-9, trans-12 C18:2) were added. Bovine serum albumin (fatty acid-free) solutions were added and cells were collected at specific time points over 48 h. Then, RNA was extracted and converted to complementary DNA for quantitative real-time PCR analysis of proinflammatory gene expression. Presence of elaidic acid caused increases in mRNA expression of interleukin (IL)-1 beta (3.4-fold; dose-independently over a 6-h period) and intercellular adhesion molecule (ICAM)-1 (up to 1.4-fold) relative to that for cells treated with no tFA, whereas expression of IL-6 and IL-8 was reduced 0.75- and 0.85-fold, respectively. Presence of linoleidic acid reduced mRNA expression of IL-6 and IL-8 relative to that for control (0.95- and 0.87-fold, respectively). Trans mono- and dienoic fatty acids upregulated mRNA expression of IL-1 beta and ICAM-1, whereas expression of IL-6 and IL-8 was downregulated in MAC-T cells. Because these genes are ultimately involved in inflammation, elaidic or linoleidic acid, either directly fed or formed in the rumen during biohydrogenation, may alter the risk for mastitis in vivo.