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

Department of Animal Production, Agricultural University of Athens, Greece.
American Journal of Veterinary Research (Impact Factor: 1.34). 01/2002; 62(12):1934-8. DOI: 10.2460/ajvr.2001.62.1934
Source: PubMed


To determine the effect of vitamin E supplementation on urokinase-plasminogen activator (u-PA) receptor (u-PAR) expression by neutrophils of dairy cows.
16 healthy Holstein dairy cows.
16 cows were assigned to 1 of 2 experimental groups: control (no vitamin E supplementation) and vitamin E supplementation. Supplementation of vitamin E started 4 weeks prior to and continued up to 4 weeks after parturition and included oral administration of vitamin E at 3,000 U/cow per day; 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, and 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 sites on the cell membrane of neutrophils.
Stimulated neutrophils isolated from cows that received vitamin E supplementation 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 differences between groups throughout the whole experimental period in u-PA binding sites of neutrophils.
The increased total cell-associated and membrane-bound u-PA activity in neutrophils isolated from cows that received vitamin E may facilitate the ability of neutrophils to extravasate and reach the mammary gland at postpartum week 1. Rapid recruitment of neutrophils is critical for proper defense of the gland.

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    • "Politis et al. (2004) reported that SA production at parturition was less than 50% of that observed 4 wk before and 4 wk after parturition. Similarly, Politis et al. (2001) reported that membrane-bound U-PA activity of neutrophils was in the range of 0.1 to 0.12 ⌬A/h per 10 6 cells around parturition and 0.3 ⌬A/h per 10 6 cells at 4 wk after parturition. In contrast, reductions in the same parameters in our study never exceeded the level of 24%. "
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    ABSTRACT: The objective of the present study was to evaluate whether immunosuppression occurs in 3 different Greek dairy sheep breeds during the periparturient period. A total of 33 ewes from 3 breeds [i.e., the low-producing Boutsiko breed (n = 11), which is highly adaptable to harsh environments; the high-producing but environmentally fragile Chios breed (n = 11); and an intermediate synthetic breed (50% Boutsiko, 25% Arta, and 25% Chios, n = 11)] were used. Blood samples were collected at 18 and 2 d before parturition and at 15 d after parturition. Total cell-associated and membrane-bound urokinase plasminogen activator (U-PA) activity, free U-PA binding sites on cellular membranes, and superoxide anion (SA) production by activated phagocytes were determined. Results indicated that all immune parameters measured remained constant during the periparturient period for the Boutsiko breed. In contrast, there were reductions in total cell-associated and membrane-bound U-PA activity by both monocytes-macrophages and neutrophils and in SA production by monocytes-macrophages at d 2 before parturition for the Chios breed. In the synthetic breed, there were reductions in total cell-associated and membrane-bound U-PA activity by monocytes-macrophages and in SA production by both monocytes-macrophages and neutrophils at d 15 after parturition. Thus, mild immunosuppression during the periparturient period was observed in the 2 breeds with the highest milk production.
    Journal of Dairy Science 01/2008; 90(12):5567-71. DOI:10.3168/jds.2007-0247 · 2.57 Impact Factor
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    • "In this study, an initial blood vitamin E level at dry off above 6.42 μg/ml was considered a risk factor for developing clinical mastitis. However in another study with average blood vitamin E levels equal to or higher than 6 μg/ml during the periparturient period, a positive rather than negative effect of supplementation on the immune function and SCC/ml levels in milk was found [41]. The plasma concentration of α-tocopherol at dry off is obviously a critical factor in determining the positive effect of vitamin E supplementation on the incidence of mastitis. "
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    ABSTRACT: Over the past decades several studies have investigated the importance of an adequate vitamin E status to sustain both animal health and production in dairy cows. Cow milk is considered as a remarkable source of bioactive components promoting human health, which has renewed interest in the effects of vitamin E supplementation on its nutritional value, sensory quality and shelf life. Thus, defining relative bioavailability, utilisation and transfer into milk of different vita-min E formulations is particularly important to assess the adequate levels of supplementation for animal health and milk quality. In nature vitamin E is present under one isomeric form, RRR α-tocopherol; when α-tocopherol is synthe-sized chemically, a racemic mixture of 8 possible isomers of α-tocopherol in equimolar concentrations is produced (all-rac α-tocopherol). The different stereoisomers have different biopotencies in humans and livestock; the conversion factor between RRR and all-rac vitamin E was estimated by early studies on the basis of the rat foetal resorption bio-assay, and then extended to other species. Recent advances on the distribution of vitamin E stereoisomers in plasma and tissues have highlighted the need to formulate new conversion factors in dairy cows as well as in humans. On ac-count of this, the present article aims to consider past and recent data related to vitamin E in dairy cow nutrition.
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    ABSTRACT: The urokinase-plasminogen activator (u-PA) system in resting and activated ovine macrophages and neutrophils was examined. Macrophages and neutrophils were isolated from a total of 28 lactating sheep of the Chios breed. Low amounts of u-PA were found intracellularly or membrane-bound in resting macrophages and neutrophils. However, incubation of resting macrophages or neutrophils with purified u-PA (10IU/ml) revealed extensive binding of u-PA to cell membranes. Excess amino terminal fragment of the u-PA molecule, a proteolytically inactive fragment of u-PA (amino acids 1–135) blocked binding of u-PA to macrophage or neutrophil cell membrane. These results indicate that the binding of u-PA is specific and that resting neutrophils and macrophages have unoccupied u-PA receptors on their cell membrane. Addition of phorbol myristate acetate (PMA) led to an increase (P
    Small Ruminant Research 04/2002; 44(1):17-23. DOI:10.1016/S0921-4488(02)00040-8 · 1.13 Impact Factor
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