Marey MA, Yousef MS, Liu J, Morita K, Sasaki M, Hayakawa H, Shimizu T, Elshahawy II, Miyamoto A. Endothelin-1 downregulates sperm phagocytosis by neutrophils in vitro: A physiological implication in bovine oviduct immunity.
J Reprod Dev 2016;
62:151-7. [PMID:
26781611 PMCID:
PMC4848572 DOI:
10.1262/jrd.2015-112]
[Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The oviduct is an active contractile tube that provides the proper environment for sperm transport,
capacitation and survival. Oviductal contractions are regulated by autocrine/paracrine secretion of several
factors, such as prostaglandins (PGs) and endothelin-1 (EDN-1). We have previously shown that during the
preovulatory stage, sperm are exposed to polymorphonuclear neutrophils (PMNs) in the bovine oviduct, and the
bovine oviduct epithelial cells (BOECs) secrete molecules including PGE2 that suppress sperm phagocytosis by
PMNs in vitro. In this study, we investigated the possible effects of EDN-1 on the phagocytic
activity of PMNs toward sperm. The local concentrations of EDN-1 in oviduct fluid and BOEC culture medium
ranged from 10–10 to 10–11 M as determined by EIA. Phagocytosis and superoxide
production were assayed by co-incubation of sperm pretreated to induce capacitation with PMNs exposed to EDN-1
(0, 10–11, 10–10, 10–9, and 10–8 M) for 2 h. EDN-1 suppressed dose
dependently (10–11 to 10–8 M) the phagocytic activity for sperm and superoxide
production of PMNs in response to capacitated sperm. Moreover, this suppression was eliminated by an
ETB receptor antagonist (BQ-788). EDN-1 suppressed mRNA expression of EDN-1 and ETB
but not ETA receptors in PMNs, suggesting the ETB receptor-mediated pathway. Scanning
electron microscopic observation revealed that incubation of PMNs with EDN-1 (10–9 M) completely
suppressed the formation of DNA-based neutrophil extracellular traps for sperm entanglement. The results
provide evidence indicating that EDN-1 may be involved in the protection of sperm from phagocytosis by PMNs in
the bovine oviduct, supporting sperm survival until fertilization.
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