An Acute-phase Protein as a Regulator of Sperm Survival in the Bovine Oviduct: Alpha 1-acid-glycoprotein Impairs Neutrophil Phagocytosis of Sperm <i>In Vitro</i>

Abstract

We have previously shown that polymorphonuclear neutrophils (PMNs) are present in bovine oviduct fluid under physiological conditions, and that the oviduct provides a microenvironment that protects sperm from phagocytosis by PMNs. Alpha 1-acid glycoprotein (AGP) is a major acute-phase protein produced mainly in the liver that has immunomodulatory functions. AGP mRNA is expressed in extrahepatic organs, such as the lung, kidney, spleen, lymph node, uterus, and ovary. Therefore, in this study, we investigated, 1) the local production of AGP in the bovine oviduct, 2) the effect of AGP on the phagocytic activity of PMNs for sperm and superoxide production and 3) the impact of AGP desialylation on the PMN phagocytosis of sperm. The AGP gene was expressed in cultured bovine oviduct epithelial cells (BOECs) and AGP protein was detected in oviduct fluid. Preexposure of PMNs to AGP at physiological levels impaired PMN phagocytosis for sperm and superoxide generation. The desialylation of AGP eliminated these suppressive effects of AGP on PMN. Scanning electron microscopy revealed that AGP drastically reduced the formation of DNA-based neutrophil extracellular traps (NETs) for sperm entanglement. Additionally, AGP dose-dependently stimulated BOECs to produce prostaglandin E2 (PGE2) which has been shown to partially contribute to the regulation of sperm phagocytosis in the bovine oviduct. AGP and PGE2 at concentrations detected in the oviducts additively suppressed sperm phagocytosis by PMNs. These results provide evidence that locally produced AGP may be involved in protecting sperm from phagocytosis by PMNs in the bovine oviduct.

Identification of Rabbit Oviductal Fluid Proteins Involved in Pre‐Fertilization Processes by Quantitative Proteomics

“…This acute‐phase protein was also altered by gametes in porcine oviducts . ORM1 suppresses spermatozoa phagocytosis by polymorphonuclear neutrophils in vitro, thus improving the survival of male gametes in the isthmic segment of the rabbit oviduct as well. This finding corroborates our strategy for identifying biologically relevant ODF proteins that support spermatozoa function/survival and simultaneously demonstrates that the same proteins are important in the reproduction processes of diverse mammalian species.…”

The role of neutrophil activation in determining the outcome of pregnancy and modulation by hormones and/or cytokines

“…It appears that additional mechanisms to that of seminal plasma are operative to ensure safe passage of the sperm as they traverse the female reproductive tract [45][46][47][48][49]. It appears that additional mechanisms to that of seminal plasma are operative to ensure safe passage of the sperm as they traverse the female reproductive tract [45][46][47][48][49].…”

Quercetin Promotes the Expression of Genes Involved in Phagocytosis in Bovine Neutrophils

“…Healthy, multiparous Holstein cows during nonlactating period were used as blood donors (Jinghui et al, 2014;Martinez et al, 2014). A total number of 15 cows in 3 independent experiments, 5 cows each, were recruited in the study.…”