Bovine oviduct epithelial cells downregulate phagocytosis of sperm by neutrophils: prostaglandin E2 as a major physiological regulator

Abstract

This study aimed to investigate the presence of polymorphonuclear neutrophils (PMNs) in bovine oviduct fluid under physiological conditions and to determine the possible role of bovine oviduct epithelial cells (BOECs) in the regulation of the phagocytic activity of PMNs for sperm. During the pre-ovulatory stage, PMNs were identified in the bovine oviduct fluid in relatively constant numbers. In our experiments, PMNs were incubated for 4 h with the supernatant of cultured BOECs stimulated for 24 h by LH (10 ng/ml). Phagocytosis was then assayed by co-incubation of these PMNs with sperm treated to induce capacitation. The BOEC supernatant significantly suppressed sperm phagocytosis by PMNs, and the LH-stimulated BOEC supernatant further suppressed phagocytosis. Importantly, in the BOEC culture, LH stimulated the secretion of prostaglandin E 2 (PGE 2 ), which dose-dependently (10 K6 , 10 K7 , and 10 K8 M) suppressed sperm phagocytosis by PMNs. Furthermore, a PGEP 2 receptor antagonist significantly abrogated the inhibition of phagocytosis by the LH-stimulated BOEC supernatant. Additionally, using scanning electron microscopy, incubation of PMNs with either PGE 2 or LH-stimulated BOEC supernatant before phagocytosis was found to prevent the formation of DNA-based neutrophil extracellular traps for sperm entanglement. The results indicate that sperm are exposed to PMNs in the oviduct and PGE 2 released into the oviduct fluid after LH stimulation may play a major role in the suppression of the phagocytic activity of PMNs for sperm via interaction with EP 2 receptors. Thus, the bovine oviduct provides a PGE 2 -rich microenvironment to protect sperm from phagocytosis by PMNs, thereby supporting sperm survival in the oviduct.Free Japanese abstract A Japanese translation of this abstract is freely available at

Leukocytes coincubated with human sperm trigger classic neutrophil extracellular traps formation, reducing sperm motility

“…(spermiophagy) (16). TEM as well as SEM analyses confirmed that both effector mechanisms are displayed by PMN exposed to vital spermatozoa, namely, phagocytosis and the NETosis process.…”

“…1) or trap them by enmeshing them through NETs (4,16). This direct cell contact between the PMN and the spermatozoon, which can result in the entrapment via the head, middle piece, or flagellum, represents the first stage of sperm phagocytosis Effect in time on the progressive motility of human sperm of incubation of PMN/sperm with different ratios (1:18, 6:18, 9:18).…”

Innate immunity and inflammation of the bovine female reproductive tract in health and disease

“…In the mouse, TLR4 may have a role in normal cumulus-oocyte complex expansion and ovulation by binding endogenous ligands such as hyaluronic acid . After ovulation, the oocyte enters the uterine tube (oviduct), and although many neutrophils are present, prostaglandin E 2 released by uterine tube epithelial cells after LH stimulation suppresses the phagocytosis of sperm by neutrophils, thereby supporting sperm survival in the uterine tube (Marey et al 2014). As well as responding to LH, the uterine tube epithelial cells have innate immune capabilities, expressing TLR2 and TLR4, and generating inflammatory responses to LPS (Kowsar et al 2013).…”

Mating for male-derived prostaglandin: a functional explanation for the increased fecundity of mated female crickets?

“…and C.D.K., unpublished), suggesting that ejaculate-derived PGE 2 has a positive effect on both egg development and oviposition. From the male perspective, prostaglandins play various roles in sperm maintenance in mammals, including sperm motility (Didolkar and Roychowdhury, 1980), viability (Hayashi et al, 1988), protection from phagocytosis (Marey et al, 2013), and enhancing the acrosome reaction necessary for the fusion of sperm and egg (Herrero et al, 1997). To our knowledge, there are no studies examining the importance of prostaglandin on sperm maintenance in insects, so further research will be required to understand these effects.…”

“…Prostaglandins are oxygenated metabolites of C 20 polyunsaturated fatty acids that are fundamental to many aspects of animal physiology (Craig, 1975;Harris et al, 2002;Wolfe and Coceani, 1979) and are found in the ejaculates of various animals (Kennedy et al, 2003;Kobayashi et al, 2013;Loher et al, 1981;Templeton et al, 1978). The biological significance of prostaglandins in mediating physiological actions essential for reproduction is well understood in mammals (Didolkar and Roychowdhury, 1980;Herrero et al, 1997;Kurzrok and Lieb, 1930;Marey et al, 2013), and is considered to be important in invertebrate reproduction as well. Prostaglandins are found in cricket seminal fluid (Loher et al, 1981) and have noted effects on the reproductive physiology of two species, Teleogryllus commodus and Acheta domesticus, in mediating egg production and oviposition in mated females (Loher and Edson, 1973;Murtaugh and Denlinger, 1985).…”