Seminal Plasma Modulates miRNA Expression by Sow Genital Tract Lining Explants

Abstract

The seminal plasma (SP) modulates the female reproductive immune environment after mating, and microRNAs (miRNAs) could participate in the process. Considering that the boar ejaculate is built by fractions differing in SP-composition, this study evaluated whether exposure of mucosal explants of the sow internal genital tract (uterus, utero-tubal junction and isthmus) to different SP-fractions changed the profile of explant-secreted miRNAs. Mucosal explants retrieved from oestrus sows (n = 3) were in vitro exposed to: Medium 199 (M199, Control) or M199 supplemented (1:40 v/v) with SP from the sperm-rich fraction (SRF), the post-SRF or the entire recomposed ejaculate, for 16 h. After, the explants were cultured in M199 for 24 h to finally collect the media for miRNA analyses using GeneChip miRNA 4.0 Array (Affymetrix). Fifteen differentially expressed (False Discovery Rate (FDR) < 0.05 and Fold-change ≥ 2) miRNAs (11 down- versus 4 up-regulated) were identified (the most in the media of uterine explants incubated with SP from post-SRF). Bioinformatics analysis identified that predicted target genes of dysregulated miRNAs, mainly miR-34b, miR-205, miR-4776-3p and miR-574-5p, were involved in functions and pathways related to immune response. In conclusion, SP is able to elicit changes in the miRNAs profile secreted by female genital tract, ultimately depending SP-composition.

Seminal Plasma: Relevant for Fertility?

“…As mentioned above, the SP EVs have demonstrated capacity to bind to and even fuse with the sperm plasma membrane to deliver their cargo [ 76 , 138 , 176 , 177 ], influencing sperm function [ 142 , 143 , 144 ], but also via proteins such as CD59, to protect spermatozoa from responses by the immune system [ 135 ]. SP EVs have also proven, as did other EVs [ 178 ], to influence the local immunity of the female internal tract [ 179 ], and to induce inflammatory and immune responses by pig uterine cells [ 4 , 38 , 180 ]. Whether the changes in immune-related genes we have detected in peri-ovulatory sows following mating or AI, with selected ejaculate fractions (particularly the sperm-peak portion) or their sperm-free SP [ 29 ], or even in sows having pre-implantation embryos [ 173 ], are conveyed mainly by free molecules, by SP-EVs or it is the effect of a concerted signaling, remains to be experimentally tested.…”

“…So, what could these miRNAs rule that impacts fertility? As already mentioned, SP has the capability of eliciting inflammatory and long-lasting immune signaling by the female genital tract [ 27 , 29 , 117 , 173 ], being even able to cause release of miRNAs from the lining epithelia [ 180 ]. Responses from the female can be issued by spermatozoa alone [ 198 ] or even by the act of copulation [ 199 ], but the evidence is that these changes are rather modest, compared to what the SP can elicit, either alone or as semen (i.e., including the suspended spermatozoa).…”

“…Responses from the female can be issued by spermatozoa alone [ 198 ] or even by the act of copulation [ 199 ], but the evidence is that these changes are rather modest, compared to what the SP can elicit, either alone or as semen (i.e., including the suspended spermatozoa). Many of the top miRNAs detected in pig spermatozoa [ 27 ] and SP EVs [ 140 ] can impact TLR4 signaling [ 200 ], and promote the production of cytokines that modulates immune responses [ 27 , 180 , 201 ] to the extent of modulating the fertility of the males considered [ 27 , 190 ].…”

Seminal Plasma Transcriptome and Proteome: Towards a Molecular Approach in the Diagnosis of Idiopathic Male Infertility

“…The seminal plasma (SP) is made-up of secretions arising from the male accessory glands, namely epididymis, seminal vesicles, and prostate. The SP is not only a medium for sperm transport, since it can modulate the female reproductive environment and immunity [ 9 ] to allow the acquisition of sperm competence [ 10 ] to influence sperm RNA content, and even embryo development, as transcriptome studies reveal [ 11 ]. In recent years, thousands of specific transcripts and proteins have been found in human seminal plasma (SP).…”

Seminal Plasma Proteomic Biomarkers of Oxidative Stress

“…It plays a crucial role in sperm survival and quality. More specifically, SP influences the female reproductive environment and immunity [16], allows the acquisition of sperm competence [17], and influences the RNA content of spermatozoa and even the embryo development, as transcriptome studies have revealed [18].…”