Effects of vitamin E on urokinase-plasminogen activator receptor expression by bovine neutrophils

Objective-To determine the effect of vitamin E supplementation on urokinase -plasminogen activator (u-PA) receptor (u-PAR) expression by neutrophils of dairy cows. Animals-16 healthy Holstein dairy cows. Procedure-16 cows were assigned to 1 of 2 experimental groups: control (no vitamin E supplementation) and Vitamin E supplementation. Supplementation o f vitamin E started 4 weeks prior to and continued up to 4 weeks after part urition and included oral administration of vitamin E at 3,000 U/cow per da y; these cows also received 1 injection of vitamin E (5,000 units), 1 week prior to the expected date of parturition. Blood samples were collected, an d neutrophils were isolated weekly throughout the experimental period. The following variables were measured: u-PA (mRNA), total cell-associated u-PA activity, membrane-bound u-PA activity, and free unoccupied u-PA binding si tes on the cell membrane of neutrophils. Results-Stimulated neutrophils isolated from cows that received vitamin E s upplementation had significantly higher u-PA mRNA and total cell-associated and membrane-bound u-PA activity at postpartum week 1, compared with those of stimulated neutrophils isolated from control cows. There were no differ ences between groups throughout the whole experimental period in u-PA bindi ng sites of neutrophils. Conclusions and Clinical Relevance-The increased total cell-associated and membrane-bound u-PA activity in neutrophils isolated from cows that receive d vitamin E may facilitate the ability of neutrophils to extravasate and re ach the mammary gland at postpartum week 1. Rapid recruitment of neutrophil s is critical for proper defense of the gland.