Evidence for a novel, local acute-phase response in the bovine oviduct: progesterone and lipopolysaccharide up-regulate alpha 1-acid-glycoprotein expression in epithelial cells in vitro.

Abstract

Little is known about the local production and function of alpha 1-acid glycoprotein (AGP), an acute-phase protein, in the female reproductive tract. This study aimed to investigate the regulation and immune function of AGP in cultured bovine oviduct epithelial cells. Analysis by Western blotting and immunohistochemistry revealed that bovine oviduct tissue expresses AGP protein in epithelial cells and the smooth muscle layer. Stimulation of bovine oviduct epithelial cells in culture with either progesterone (1 ng/ml) or lipopolysaccharide (LPS, 10 ng/ml) induced both mRNA expression and secretion of AGP. Estradiol (1 ng/ml), progesterone (1 ng/ml), and luteinizing hormone (10 ng/ml), which are observed during the peri-ovulatory period in oviduct tissues (steroids) or in circulation (luteinizing hormone), suppressed LPS-induced expression and secretion of AGP, which in turn induced the expression of Toll-like receptor-4 (TLR-4) and interleukin-1β (IL-1B), but suppressed TLR-2 and tumor necrosis factor-α (TNFA) expression. AGP also inhibited LPS-induced TLR-2 and TNFA expression, but had no effect on LPS-induced TLR-4 and IL-1B expression. These findings suggest that oviductal epithelial cells can participate in antimicrobial processes through the secretion of AGP, which is partly regulated by ovarian steroids. Moreover, oviductal AGP may regulate the response of epithelial cells, thereby reducing the expression of the acute pro-inflammatory cytokine TNFA, which could contribute to the local homeostasis during the acute response to endotoxin release in the oviduct's anti-infection process.