Influence of sex steroids on the viability and CD11b, CD18 and CD47 expression of blood neutrophils from dairy cows in the last month of gestation

Abstract

In the period around parturition, cows experience an increased susceptibility for the development of Escherichia coli mastitis. This increased susceptibility has been correlated with a decreased functionality of neutrophils. In the current study, it is suggested that the decreased neutrophil functionality may be induced by the extensive alterations in sex steroid levels occurring around parturition. It was first hypothesized that 17β-estradiol and progesterone influence the viability, apoptosis and necrosis of blood neutrophils from cows in their last month of gestation. Subsequently, it was hypothesized that 17β-estradiol modulates the expression of CD11b, CD18 or CD47 thereby explaining its influence on the migration of bovine neutrophils. Neither 17β-estradiol nor progesterone significantly influenced viability, apoptosis or necrosis in spontaneous apoptosis conditions. However, when apoptosis was induced with TNF-α and gliotoxin, progesterone exerted a survival effect (P < 0.05). In addition, 17β-estradiol treatment of bovine blood neutrophils significantly decreased the expression of CD47 (P < 0.05) but not of CD11b or CD18. It can be concluded that 17β-estradiol and progesterone do not affect spontaneous apoptosis of bovine blood neutrophils while a survival effect was observed for progesterone on induced neutrophils apoptosis. Moreover, our results concerning the influence of 17β-estradiol on the CD11b, CD18 and CD47 expression extend previous demonstrations of the suppressive effect of 17β-estradiol on neutrophils migration and indicate that the altered expression of CD47 may contribute to this phenomenon. © INRA, EDP Sciences, 2005.