Prepartum organic selenium supplementation influences postpartum inflammatory response by regulating plasma oxylipin...

Excessive lipolysis and enhanced inflammation in periparturient dairy cows may lead to metabolic disorders and diseases. Membrane phospholipids and lipid mobilisation-released polyunsaturated fatty acids (PUFAs) can be oxidised into oxylipins that have pro- and/or anti-inflammatory roles. Selenium has immunomodulatory and anti-inflammatory effects, but the mechanisms are not yet fully understood. The objective of this study was to examine the effects of prepartum selenium-yeast (SY) supplementation on the inflammatory response in dairy cows during the periparturient period by regulating plasma oxylipin profiles. Fourteen cows were randomly assigned to two groups. Cows in one group were provided with a TMR containing sodium selenite at 0.3 mg Se/kg DM. Cows in the other group received SY at a dosage of 0.2 mg Se/kg DM during the last 4 weeks of pregnancy, in addition to being fed the same TMR as the control group. Blood was sampled on d -28, 1, 7, 14, and 28 relative to parturition for targeted oxylipin assays. A total of 53 of 134 oxylipins were detected in plasma. Dietary treatment mainly affected plasma linoleic acid-, arachidonic acid-, and eicosapentaenoic acid-derived oxylipins. For linoleic acid-derived oxylipins, anti-inflammatory 13-oxo-octadecadienoic acid was increased in the SY supplemented group as compared with the control. For arachidonic acid-derived oxylipins, prepartum SY supplementation decreased pro-inflammatory prostaglandin (PG) E2, 5- and 12-hydroxyeicosatetraenoic acid (HETE), as well as 5-oxo-eicosatetraenoic acid, while increasing or tending to increase anti-inflammatory 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids. The increased 15-keto-PGF2α and 20-Carboxy-arachidonic acid in the SY-supplemented group indicate that selenium may promote the conversion of pro-inflammatory PGF2α and 20-HETE into their respective inactive metabolites. For eicosapentaenoic acid-derived oxylipins, prepartum SY supplementation increased or tended to increase anti-inflammatory 5-, 15-, and 18-hydroxyeicosapentaenoic acids, as well as 14,15- and 17,18-epoxyeicosatetraenoic acids. Prepartum SY supplementation also increased or tended to increase the ratios of linoleic acid- and arachidonic acid-derived epoxy fatty acids to their corresponding diols, suggesting that selenium may stimulate a shift in the cytochrome P450 epoxygenase-derived oxylipin profile towards anti-inflammatory activity. Additionally, an increased plasma total PUFA and a reduced ratio of n-6 to n-3 PUFA in response to SY supplementation were observed in this study. Taken together, our study demonstrates that prepartum SY supplementation attenuates bovine postpartum inflammation by promoting the production of anti-inflammatory oxylipins and inhibiting that of pro-inflammatory oxylipins. These effects may be associated with selenium-mediated regulation of substrate availability, enzymatic oxidation pathways, and the degree of oxylipin metabolism.