The Seminal Plasma of the Boar is Rich in Cytokines, with Significant Individual and Intra-Ejaculate Variation

Abstract

Problem: The boar, as human, sequentially ejaculates sperm-rich and sperm-poor fractions.Seminal plasma (SP) spermadhesins (PSP-I/PSP-II) induce a primary endometrial inflammatory response in female sows, similar to that elicited by semen deposition in other species, including human. However, the SP is also known to mitigate such response, making it transient to allow for embryo entry to a cleansed endometrium. Although cytokineinvolvement has been claimed, the exploration of cytokines in different SP-fractions is scarce. This study determines Th1, Th2, Th17 and Th3 cytokine profiles in specific ejaculate SP-fractions from boars of proven fertility. Conclusions: Boar SP is rich in Th1, Th2, Th17 and Th3 cytokines, with lowest concentrations in the sperm peak-containing fraction, indicating its main immune influence might reside in the larger, protein-rich sperm-poor post-SRF.

Will AI in pigs become more efficient?

“…This handling is now switching towards a growing interest to scrutinize SP-composition and evaluate its relevance for sperm functionality, even fertility. Recent findings support the complex composition of boar SP [50][51][52] and also demonstrate the relevance of some SP-components, such as Glutathione Peroxidase 5 [53] or Paraoxonase-I [54], for promoting sperm fertility of liquid stored semen IA-doses.…”

“…The boar SP is especially rich in cytokines (a total of 14 have been recently found in measurable amounts, [52]). Cytokines act as signals for the female immune system once into the female genital tract, modulating the maternal tolerance towards embryo and placental development, thus conditioning embryo/foetal development [58].…”

Characterization of the porcine seminal plasma proteome comparing ejaculate portions

“…In this context, it is well known that the total protein composition differs among boar ejaculate fractions [43]. As in human, the boar ejaculate is expelled in fractions, the SRF and the post-SRF being the two main fractions, with relevant differences in SP-composition [43] including cytokine-contents [44] and antioxidant enzymes [45]. Further research is required to verify possible divergences in the SP-proteome among ejaculate fractions/portions, particularly in the light of the ongoing discussions as to whether to use only the SRF or the entire ejaculate for both AI and sperm technologies, such as cryopreservation and sex-sorting [2].…”

The ubiquitous hyaluronan: Functionally implicated in the oviduct?

“…Seminal plasma causes a transient inflammatory reaction in the cervix and uterus of pig (and other species, including human) that conveys to cleanse the lumen from foreign spermatozoa, other cells, microorganisms and seminal plasma proteins. That inflammation is caused by specific seminal plasma proteins (as PSP-I/II, [59]) but also through the entry of seminal plasma-bearing pro-inflammatory cytokines [60]. At the same time, the boar seminal plasma also contains antiinflammatory cytokines [60] as well as it stimulates (in human, via E-type prostaglandins, [61]) the production of cervical and uterine IL-10, a clearly anti-inflammatory cytokine.…”

“…That inflammation is caused by specific seminal plasma proteins (as PSP-I/II, [59]) but also through the entry of seminal plasma-bearing pro-inflammatory cytokines [60]. At the same time, the boar seminal plasma also contains antiinflammatory cytokines [60] as well as it stimulates (in human, via E-type prostaglandins, [61]) the production of cervical and uterine IL-10, a clearly anti-inflammatory cytokine. Such production of IL-10 is also induced from implants delivering hyaluronan [61]).…”