Effect of bovine seminal plasma on bovine endometrial epithelial cells in culture

Review: The role of male reproductive tract secretions in ruminant fertility

Male fertility largely depends on the ability to produce sperm that can transmit the paternal information onto the next generation. However, the factors that are critical for sperm function and the subsequent development of healthy offspring are still not completely understood in ruminants. Importantly, sperm function is not completely encoded by germ cell DNA, but rather, depends on sequential acquisition, loss, and modification of elements through interaction with secretions from the testes, epididymides, and accessory glands (collectively termed seminal plasma). In addition, these secretions can play a role in the inheritance of paternal environmental effects by progeny. This is likely achieved directly, by the regulation of sperm epigenetic effectors, and indirectly, by altering the female environment in which the individual develops. This review will provide an overview of the different organs that contribute to seminal plasma in ruminants, and summarise how their secretions shape sperm function and modulate the female reproductive tract. Finally, some consideration will be given to the potential of paternal factors to affect embryo development and offspring health in ruminants.

Ovulation Induced by Intrauterine Seminal Plasma Increases Total Protein, PGE2, IL-8, and IL-1β in Uterine Fluid of Llamas (Lama glama)

The establishment of a state of immunotolerance in the female reproductive tract is important for embryo development, implantation and placentation. Llamas are induced ovulators and more than 98% of pregnancies occur in the left uterine horn. The objective of this study was to determine the uterine immune response of llamas in different stages of the reproductive cycle. Adult llamas (n = 20) were examined daily by transrectal ultrasonography to determine follicular growth and then randomly assigned to four groups: Follicular phase (n = 5); Luteal phase induced by an intramuscular administration of 50 ug of GnRH analogue (n = 5); Luteal phase induced by intrauterine infusion of seminal plasma (n = 5); and Luteal phase induced by mating (n = 5). Uterine fluid was collected separately from both uterine horns by non-surgical flushing to determine the presence of cells, total proteins and concentration of IL-1β, IL-6, IL-8, IFN γ, TNF-α and PGE2. Inflammatory cells were not observed in the uterine fluid and total protein pattern and inflammatory mediators did not differ between the left and the right horn amongst groups. Llamas treated with an intrauterine infusion of seminal plasma showed the highest concentration of total proteins, inflammatory cytokines PGE2, IL-8 and IL-1β in the uterine fluid. In conclusion, seminal plasma is made up of significant numbers of signaling molecules that are able to modify the uterine immune response in llamas.

Protein Identification of Seminal Plasma in Bali Bull (Bos javanicus)

The purpose of this study was to identify seminal plasma proteins in Bali bull and their potential as biomarkers of fertility. Semen was collected from 10 bulls aged 5-10 years using an artificial vagina. Fresh semen was then centrifuged (3000× g for 30 min). The supernatant was put into straws and stored in liquid nitrogen. The semen plasma protein concentration was determined using the Bradford method, and the protein was characterized using 1D-SDS-PAGE. Coomassie Brilliant Blue (CBB) was used to color the gel, and the molecular weight of the protein was determined using PM2700. A total of 94 proteins were identified in the seminal plasma of Bali bulls analyzed using LC-MS/MS (liquid chromatography-mass spectrometry). Proteins spermadhesin 1 (SPADH1), C-type natriuretic peptide (NPPC), clusterin (CLU), apoliprotein A-II (APOA2), inositol-3-phosphate synthase 1 (ISYNA1), and sulfhydryl oxidase 1 (QSOX1) were identified as important for fertility in Bos javanicus. These proteins may prove to be important biomarkers of fertility in Bali bulls. These proteins are important for reproductive function, which includes spermatozoa motility, capacitation, and acrosome reactions. This study provides new information about the protein content in seminal plasma in Bali bulls. The LC-MS/MS-based proteome approach that we applied in this study obtained 94 proteins. The identification of these seminal plasma proteins of Bali bulls and their potential as fertility biomarkers may have an impact on the success of future artificial insemination (AI).

Effect of insulin-like growth factor-1 complex of Simmental bull seminal plasma on post-thawed Kacang buck semen fertility

Background and Aim

Kacang buck sperm is cryosensitive due to the seminal plasma of semen itself. Meanwhile, bull seminal plasma contains the insulin-like growth factor-1 (IGF-1) complex, which is cryoprotective. The addition of the crude protein of Simmental bull seminal plasma increased the quality of post-thawed semen of Kacang buck. The study was conducted to determine the effects of Simmental bull seminal plasma with IGF-1 on the fertility of post-thawed Kacang buck semen.

Materials and Methods

Buck semen was diluted in the following skim milk-egg yolk extender preparations: Without the addition of Simmental bull seminal plasma IGF-1 complex protein (T0); with the addition of 12-μg Simmental bull seminal plasma IGF-1 complex protein (T1); and with the addition of 24-μg Simmental bull seminal plasma IGF-1 complex protein (T2). The extended semen was packed in 0.25-mL straws and frozen. Post-thawed semen fertility was evaluated based on the following variables: Sperm motility, viability, intact plasma membrane (IPM), malondialdehyde (MDA) levels, capacitation status, and acrosome reaction. The difference in each variable among the groups was evaluated using analysis of variance, followed by Tukey's honestly significant difference test, at a 95% level of significance. Meanwhile, principal component analysis (PCA) was used to identify the principal component of semen fertility among the seven parameters.

Results

The T1 group showed the highest sperm motility, viability, IPM, and percentage of incapacitated sperm and the lowest MDA levels, percentage of capacitated sperm, and acrosome reaction. PCA revealed that sperm motility had a moderate to very robust correlation with other variables and is the most crucial parameter, accounting for 80.79% of all variables.

Conclusion

The IGF-1 complex in Simmental bull seminal plasma was useful for increasing the fertility of post-thawed Kacang buck semen, and sperm motility was the principal component of semen fertility.

Local action of cytokines and immune cells in communication between the conceptus and uterus during the critical period of early embryo development, attachment and implantation - Implications for embryo survival in cattle: A review

Early embryo development, implantation and pregnancy involve a complex dialogue between the embryo and mother. In cattle this dialogue starts as early as days 3-4 when the embryo is still in the oviduct, and it continues to implantation. Immunological processes involving cytokines, mast cells and macrophages form an important part of this dialogue. Amongst the cytokines, interleukin-6 (Il-6) and leukemia inhibitory factor (LIF) are secreted by both the embryo and uterine endometrium and form part of an ongoing and reciprocating dialogue. Mast cells and macrophages populate the uterine endometrium during embryo development and are involved in achieving the correct balance between inflammatory and anti-inflammatory reactions at the uterus that are associated with embryo attachment and implantation. Embryo loss is the major cause of reproductive wastage in cattle, and livestock generally. A deeper understanding of immunological processes during early embryo development will help to achieve the next step change in the efficiency of natural and assisted breeding.

Stable bull fertility protein markers in seminal plasma

Bull fertility is an important trait in breeding as the semen of one bull can, potentially, be used to perform thousands of inseminations. The high number of inseminations needed to obtain reliable measures from Non-Return Rates to oestrus creates difficulties in assessing fertility accurately. Improving molecular knowledge of seminal properties may provide ways to facilitate selection of bulls with good semen quality. In this study, liquid chromatography mass spectrometry (LC-MS/MS) was used to analyze the protein content from the seminal plasma of 20 bulls with Non-Return Rates between 35 and 60%, sampled across three seasons. Overall, 1343 proteins were identified and proteins with consistent correlation to fertility across multiple seasons found. From these, nine protein groups had a significant Pearson correlation (p < 0.1) with fertility in all three seasons and 34 protein groups had a similar correlation in at least two seasons. Among notable proteins showing a high and consistent correlation across seasons were Osteopontin, a lipase (LIPA) and N-acetylglucosamine-1phosphotransferase subunit gamma. Three proteins were combined in a multiple linear regression to predict fertility (r = 0.81). These sets of proteins represent potential markers, which could be used by the breeding industry to phenotype bull fertility. SIGNIFICANCE: The ability of bull spermatozoa to fertilize oocytes is crucial for breeding efficiency. However, the reliability of this trait from field measures is relatively low and the prediction of fertility given by conventional methods to evaluate sperm quality is currently not very accurate. In this work, we identify sets of proteins in bull seminal plasma from repeated samples collected at different times of the year that correlate to fertility in a consistent way. We combined these individual proteins to build a molecular signature predictive of fertility. This study provides an overview of proteins linked to fertility in seminal plasma, thereby increasing knowledge of the bull seminal plasma proteome. Protein signatures from the latter, potentially related to fertility, may be of use to predict fertility for individual bulls.

Effect of Simmental bull seminal plasma protein in egg yolk-citrate extender on Kacang buck semen fertility

The genetic resources of Indonesia's indigenous Kacang goat require preservation. Artificial insemination is expected to accelerate population increases and preserve genetic resources simultaneously. The present study was the maiden attempt for cryopreservation of Kacang buck sperm. The objectives of this study were to determine whether the supplementation of superior Simmental bull seminal plasma protein in egg yolk-citrate extender could improve the quality of post-thawed Kacang buck sperm, increase conceptions rates, and improve kidding rates. Buck semen was diluted without supplementation (T0) and with supplementation of 2.5 mg (T1) and 5 mg (T2) of Simmental bull seminal plasma protein per mL egg yolk-citrate extender. Extended semen was packed in 0.25 mL straw as cryopreserved frozen semen. Post-thawed semen samples were evaluated for viability, motility, intact plasma membranes, malondialdehyde level, and DNA fragmentation. Estrus was synchronized for sixty Kacang does, which were divided randomly into three groups and inseminated using post-thawed semen. The progesterone serum concentration of the does was measured 7 and 22 days post-insemination to detect ovulation and conception. Pregnancy was confirmed using abdominal palpation at 43 days post-insemination and by observing birth. The T1 group showed the highest (P < 0.05) post-thawed viability, motility, and intact plasma membrane. Conception, pregnancy and kidding rates were also higher in T1 than other treatment groups. In conclusion, the 2.5 mg Simmental bull seminal plasma protein supplementation per mL egg yolk-citrate extender provided the best seminal quality and fertility of post-thawed Kacang buck semen.

Bull seminal plasma stimulates in vitro production of TGF-β, IL-6 and IL-8 from bovine endometrial epithelial cells, depending on dose and bull fertility

Seminal plasma (SP) regulates immune responses in the female reproductive tract through specific cytokines. It is not known whether SP from high fertility bulls (H) differs from SP from low fertility bulls (L). In this study, the cytokine response of bovine endometrial epithelial cells (bEEC) in culture was investigated after challenge with SP from two bulls of below average (L) or three bulls of above average fertility (H). The bEECs were challenged with 1% or 4% SP from l- or H-fertility bulls (L1, L4, H1, H4, respectively) or 1% or 4% PBS as control (C1, C4) for 72 h. The culture media were analysed for concentrations (pg/million cells) of transforming growth factor beta (TGF-β1, TGF-β2 and TGF-β3) by Luminex, and Interleukin 6 and 8 (IL-6, IL-8) by ELISA. Challenge significantly affected production of TGF-ß1, TGF-ß2 and IL-8 compared to controls and was affected by bull fertility (p < 0.0001), SP concentration (p < 0.0001) and their interaction (p < 0.0001). A higher production of TGF-β1, TGF-β2 and IL-8 (p < 0.0001), and also IL-6 (p < 0.01), resulted from challenge with high doses of SP, being higher for L than H (p < 0.05). For TGF-β3, fertility of bull (p < 0.05). For TGF-B3, fertility of bull (p < 0.05) and the interaction between fertility and concentration of SP were significant (p < 0.01). In conclusion, 4% SP from L bulls stimulated more TGF-β1, TGF-β2, TGF-β3, IL-6 and IL-8 production than SP from H bulls, indicating that stimulation of the endometrium is relevant for fertility. Seminal plasma from high fertility bulls seems to affect cytokine production in utero positively in inseminated cows.

Species-specific and collection method-dependent differences in endometrial susceptibility to seminal plasma-induced RNA degradation

This study aimed to determine the effect of bull seminal plasma (SP) and sperm on endometrial function. Bovine endometrial explants were incubated with: ejaculated sperm with or without SP, epididymal sperm, or SP alone. Neither ejaculated nor epididymal sperm induced differential expression of IL1A, IL1B, IL6, IL8, PTGES2, TNFA, and LIF. Interestingly, SP had a detrimental effect on endometrial RNA integrity. Addition of an RNase inactivation reagent to SP blocked this effect, evidencing a role for a SP-RNase. Because bulls deposit the ejaculate in the vagina, we hypothesized that the bovine endometrium is more sensitive to SP-RNase than vaginal and cervical tissues (which come into contact with SP during mating), or to endometrium from intrauterine ejaculators (such as the horse). In addition, due to differences in SP-RNase abundance depending on SP collection method (i.e., with an artificial vagina, AV, or by electroejaculation, EE), this effect was also tested. Bull SP, collected by AV, degrades RNA of mare endometrium, and bovine vagina, cervix and endometrium. However, stallion SP or bull SP collected by EE did not elicit this effect. Thus, results do not support a role for SP in modulating endometrial function to establish pregnancy in cattle.