Seminal plasma, and not sperm, induces time and concentration-dependent neutrophil extracellular trap release in donkeys

Yentel Mateo-Otero; Fabiola Zambrano; Jaime Catalán; Raúl Sánchez; Marc Yeste; Jordi Miro; Beatriz Fernandez-Fuertes

doi:10.1111/evj.13457

Seminal plasma, and not sperm, induces time and concentration-dependent neutrophil extracellular trap release in donkeys

Equine Vet J. 2022 Mar;54(2):415-426. doi: 10.1111/evj.13457. Epub 2021 Jun 1.

Authors

Yentel Mateo-Otero^{1

2}, Fabiola Zambrano^{3

4}, Jaime Catalán^{1

2

5}, Raúl Sánchez^{3

4}, Marc Yeste^{1

2}, Jordi Miro⁵, Beatriz Fernandez-Fuertes^{1

2}

Affiliations

¹ Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, Girona, Spain.
² Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, Girona, Spain.
³ Laboratory in Reproductive Medicine and Molecular Endocrinology, Center of Excellence in Translational Medicine-Scientific and Technological Bioresource Nucleus (CEMT - BIOREN), Universidad de La Frontera, Temuco, Chile.
⁴ Department of Preclinical Sciences, Faculty of Medicine, University of La Frontera, Temuco, Chile.
⁵ Equine Reproduction Service, Department of Animal Medicine and Surgery, Faculty of Veterinary Sciences, Autonomous University of Barcelona, Barcelona, Spain.

PMID: 33908643
DOI: 10.1111/evj.13457

Abstract

Background: In several mammalian species, acute endometritis driven by the recruitment of polymorphonuclear cells (PMN) occurs in response to semen. These PMNs release DNA to form neutrophil extracellular traps (NETs) in cattle, horse and human, leading to sperm entrapment. While there is no evidence of this phenomenon occurring in donkeys, artificial insemination (AI) with frozen-thawed semen, which results in very poor pregnancy rates, leads to a large PMN recruitment to the uterus.

Objectives: To investigate whether donkey semen can trigger NET release (NETosis) and if excessive NETosis occurs in response to frozen-thawed semen.

Study design: In vitro experiments.

Methods: Jenny PMNs were exposed to jackass fresh or frozen-thawed semen, isolated sperm or seminal plasma (SP), over the course of three experiments. NET formation in response to different treatments was assessed through manual quantification of stained slides. A one-way analysis of variance (ANOVA), followed by a post hoc Sidak test, was carried out to determine statistical significance.

Results: NET release occurred in a semen concentration- and incubation-time-dependent manner. Surprisingly, frozen-thawed donkey sperm did not increase NETosis rate in comparison with the control (23 ± 2.5% vs. 31 ± 3.7%; P > .05), whereas fresh semen exposure did (78 ± 5.7% vs. 26 ± 3.2%, P < .01). NETosis increased in the presence of SP, regardless of the presence or absence of sperm, in comparison with the control in both fresh (84 ± 5.2% and 77 ± 5.0% vs. 12 ± 2.7%, respectively; P < .01) and frozen (95 ± 2.2% and 94 ± 2.9% vs. 14 ± 3.8%, respectively; P < .01) samples. Moreover, exposure of PMN to viable and motile sperm, in the absence of SP, did not increase NETosis rates (P > .05).

Conclusions: Donkey SP, and not sperm-intrinsic factors, is able to trigger NETosis in both time- and semen concentration-dependent manner. The physiological relevance of such response against semen in the donkey remains to be elucidated.

Keywords: NETosis; PMN; donkey; horse; seminal plasma.

MeSH terms

Animals
Cryopreservation / veterinary
Equidae
Extracellular Traps*
Female
Insemination, Artificial / veterinary
Male
Pregnancy
Semen
Semen Preservation* / veterinary
Spermatozoa

Abstract

MeSH terms

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