Gametes alter the oviductal secretory proteome

Oviductal extracellular vesicles miRNA cargo varies in response to embryos and their quality

BACKGROUND

Increasing evidence points to an active role of oviductal extracellular vesicles (oEVs) in the early embryo-maternal dialogue. However, it remains unclear whether oEVs contribute to the recognition of the presence of embryos and their quality in the oviduct. Hence, we examined whether the molecular cargo of oEVs secreted by bovine oviduct epithelial cells (BOEC) differs depending on the presence of good (≥ 8 cells, G) or poor (< 8 cells, P) quality embryos. In addition, differences in RNA profiles between G and P embryos were analyzed in attempt to distinguish oEVs and embryonic EVs cargos.

METHODS

For this purpose, primary BOEC were co-cultured with in vitro produced embryos (IVP) 53 h post fertilization as follows: BOEC with G embryos (BGE); BOEC with P embryos (BPE); G embryos alone (GE); P embryos alone (PE); BOEC alone (B) and medium control (M). After 24 h of co-culture, conditioned media were collected from all groups and EVs were isolated and characterized. MicroRNA profiling of EVs and embryos was performed by small RNA-sequencing.

RESULTS

In EVs, 84 miRNAs were identified, with 8 differentially abundant (DA) miRNAs for BGE vs. B and 4 for BPE vs. B (P-value < 0.01). In embryos, 187 miRNAs were identified, with 12 DA miRNAs for BGE vs. BPE, 3 for G vs. P, 8 for BGE vs. GE, and 11 for BPE vs. PE (P-value < 0.01).

CONCLUSIONS

These results indicated that oEVs are involved in the oviductal-embryo recognition and pointed to specific miRNAs with signaling and supporting roles during early embryo development.

Expression and localization of apelin and apelin receptor protein in the oviduct of letrozole-induced hyperandrogenized mice

Apelin and its receptor (APJ) are expressed in the reproductive organs of some mammalian females. The function of oviduct has also been suggested to be compromised in the hyperandrogenism condition. However, expression of apelin and APJ has not been shown in the oviduct of hyperandrogenized mice. Thus, the present study has investigated the localization and expression of apelin and APJ in the letrozole-induced hyperandrogenized mice oviduct. Histomorphometric analysis showed decreased lumen of oviduct in the hyperandrogenized mice. Our results showed elevated expression of APJ and decreased abundance of apelin in the hyperandrogenized mice oviduct. This finding suggests impaired apelin signaling in the oviduct of hyperandrogenized mice. The expression of androgen receptor was upregulated while estrogen receptors were downregulated in the hyperandrogenized mice. The expression of HSP70 was also downregulated along with increased expression of active caspase 3 and BAX and decreased expression of BCL2 in hyperandrogenized mice. Furthermore, the phosphorylation of phospho-Ser473-Akt and phospho-Thr308-Akt also showed differential levels in the oviduct of hyperandrogenized mice. Whether this differential phosphorylation of Akt was solely due to impaired apelin signaling in the oviduct, remains unclear. Moreover, increased androgen signaling and suppressed estrogen signaling coincides with elevated apoptosis. In conclusion, hyperandrogenized conditions could also impair the gamete transport and fertilization process due to apoptosis in the oviduct. However, further study would be required to unravel the exact role of apelin signaling in the oviduct in relation to apoptosis.

Cytokine profile in peripheral blood mononuclear cells differs between embryo donor and potential recipient sows

Introduction

Pregnancy success relies on the establishment of a delicate immune balance that requires the early activation of a series of local and systemic immune mechanisms. The changes in the immunological profile that are normally occurring in the pregnant uterus does not take place in cyclic (non-pregnant) uterus, a fact that has been widely explored in pigs at the tissue local level. Such differences would be especially important in the context of embryo transfer (ET), where a growing body of literature indicates that immunological differences at the uterine level between donors and recipients may significantly impact embryonic mortality. However, whether components of peripheral immunity also play a role in this context remains unknown. Accordingly, our hypothesis is that the immune status of donor sows differs from potential recipients, not only at the tissue local level but also at the systemic level. These differences could contribute to the high embryonic mortality rates occurring in ET programs.

Methods

In this study differences in systemic immunity, based on cytokine gene expression profile in peripheral blood mononuclear cells (PBMCs), between embryo-bearing donor (DO group; N = 10) and potential recipient sows (RE group; N = 10) at Day 6 after the onset of the estrus were explored. Gene expression analysis was conducted for 6 proinflammatory (IL-1α, IL-1β, IL-2, GM-CSF, IFN-γ, and TNF-α) and 6 anti-inflammatory (IL-4, IL-6, IL-10, IL-13, TGF-β1, and LIF) cytokines.

Results and discussion

All cytokines were overexpressed in the DO group except for IL-4, suggesting that stimuli derived from the insemination and/or the resultant embryos modify the systemic immune profile in DO sows compared to RE (lacking these stimuli). Our results also suggest that certain cytokines (e.g., IL-1α and IL-1β) might have a predictive value for the pregnancy status.

Proteomic Approaches to Unravel the Molecular Dynamics of Early Pregnancy in Farm Animals: An In-Depth Review

Infertility is a major problem in farm animals, which has a negative economic effect on farm industries. Infertility can be defined as the inability of animals to achieve a successful pregnancy. Early pregnancy is crucial to establish a successful pregnancy, and it is reported that 70-80% and 20-30% of total embryonic loss occur in cattle and pigs, respectively, during the first month of pregnancy. The advanced high-throughput proteomics techniques provide valuable tools for in-depth understanding of the implantation process in farm animals. In the present review, our goal was to compile, assess, and integrate the latest proteomic research on farm animals, specifically focused on female reproduction, which involves endometrial tissues, uterine fluids, oviductal fluids, and microRNAs. The series of studies has provided in-depth insights into the events of the implantation process by unfolding the molecular landscape of the uterine tract. The discussed data are related to pregnant vs. non-pregnant animals, pregnancy vs. oestrous cycle, different days of the early pregnancy phase, and animals with uterine infections affecting reproduction health. Some of the studies have utilized non-invasive methods and in vitro models to decipher the molecular events of embryo-maternal interaction. The proteomics data are valuable sources for discovering biomarkers for infertility in ruminants and new regulatory pathways governing embryo-uterine interaction, endometrium receptivity, and embryonic development. Here, we envisage that the identified protein signatures can serve as potential therapeutic targets and biomarkers to develop new therapeutics against pregnancy diseases.

Extracellular Vesicles Secreted by Pre-Hatching Bovine Embryos Produced In Vitro and In Vivo Alter the Expression of IFNtau-Stimulated Genes in Bovine Endometrial Cells

The embryo-maternal interaction occurs during the early stages of embryo development and is essential for the implantation and full-term development of the embryo. In bovines, the secretion of interferon Tau (IFNT) during elongation is the main signal for pregnancy recognition, but its expression starts around the blastocyst stage. Embryos release extracellular vesicles (EVs) as an alternative mechanism of embryo-maternal communication. The aim of the study was to determine whether EVs secreted by bovine embryos during blastulation (D5-D7) could induce transcriptomic modifications, activating IFNT signaling in endometrial cells. Additionally, it aims to assess whether the EVs secreted by embryos produced in vivo (EVs-IVV) or in vitro (EVs-IVP) have different effects on the transcriptomic profiles of the endometrial cells. In vitro- and in vivo-produced bovine morulae were selected and individually cultured for 48 h to collect embryonic EVs (E-EVs) secreted during blastulation. E-EVs stained with PKH67 were added to in vitro-cultured bovine endometrial cells to assess EV internalization. The effect of EVs on the transcriptomic profile of endometrial cells was determined by RNA sequencing. EVs from both types of embryos induced several classical and non-classical IFNT-stimulated genes (ISGs) and other pathways related to endometrial function in epithelial endometrial cells. Higher numbers of differentially expressed genes (3552) were induced by EVs released by IVP embryos compared to EVs from IVV (1838). Gene ontology analysis showed that EVs-IVP/IVV induced the upregulation of the extracellular exosome pathway, the cellular response to stimulus, and the protein modification processes. This work provides evidence regarding the effect of embryo origin (in vivo or in vitro) on the early embryo-maternal interaction mediated by extracellular vesicles.

Proteomic Profiling of Fallopian Tube-Derived Extracellular Vesicles Using a Microfluidic Tissue-on-Chip System

The human fallopian tube epithelium (hFTE) is the site of fertilization, early embryo development, and the origin of most high-grade serous ovarian cancers (HGSOCs). Little is known about the content and functions of hFTE-derived small extracellular vesicles (sEVs) due to the limitations of biomaterials and proper culture methods. We have established a microfluidic platform to culture hFTE for EV collection with adequate yield for mass spectrometry-based proteomic profiling, and reported 295 common hFTE sEV proteins for the first time. These proteins are associated with exocytosis, neutrophil degranulation, and wound healing, and some are crucial for fertilization processes. In addition, by correlating sEV protein profiles with hFTE tissue transcripts characterized using GeoMx® Cancer Transcriptome Atlas, spatial transcriptomics analysis revealed cell-type-specific transcripts of hFTE that encode sEVs proteins, among which, FLNA, TUBB, JUP, and FLNC were differentially expressed in secretory cells, the precursor cells for HGSOC. Our study provides insights into the establishment of the baseline proteomic profile of sEVs derived from hFTE tissue, and its correlation with hFTE lineage-specific transcripts, which can be used to evaluate whether the fallopian tube shifts its sEV cargo during ovarian cancer carcinogenesis and the role of sEV proteins in fallopian tube reproductive functions.

Conservation Biology and Reproduction in a Time of Developmental Plasticity

The objective of this review is to ask whether, and how, principles in conservation biology may need to be revisited in light of new knowledge about the power of epigenetics to alter developmental pathways. Importantly, conservation breeding programmes, used widely by zoological parks and aquariums, may appear in some cases to reduce fitness by decreasing animals' abilities to cope when confronted with the 'wild side' of their natural habitats. Would less comfortable captive conditions lead to the selection of individuals that, despite being adapted to life in a captive environment, be better able to thrive if relocated to a more natural environment? While threatened populations may benefit from advanced reproductive technologies, these may actually induce undesirable epigenetic changes. Thus, there may be inherent risks to the health and welfare of offspring (as is suspected in humans). Advanced breeding technologies, especially those that aim to regenerate the rarest species using stem cell reprogramming and artificial gametes, may also lead to unwanted epigenetic modifications. Current knowledge is still incomplete, and therefore ethical decisions about novel breeding methods remain controversial and difficult to resolve.

Sperm-oviduct interaction: Differential gene expression of growth factors induced by sperm DNA fragmentation

The present study investigated the effects of DNA fragmentation of spermatozoa on the growth factors expression by a human oviduct epithelial cell line (OE-E6/E7). Two separate groups were examined in this study. The cell line was cultured in the presence of spermatozoa with normal DNA fragmentation index (DFI) or abnormal DFI. Total RNA from the cell line in each group was isolated, and relative expression of objective genes was analysed using PCR array. Also, the concentration of VEGF, BMP-2, BMP-7 and MSTN in the supernatant of cell culture was analysed by the ELISA method. The PCR array analysis revealed that most of the growth factors had been upregulated in the abnormal group. However, the differences between groups were statistically significant (p < 0.05) for five genes, including VEGF-A, BMP-2, BMP-6, BMP-7 and OSM. Furthermore, MSTN was the only gene that down-regulated significantly under the influence of the spermatozoa with abnormal DFI. Moreover, the results of ELISA analysis were in agreement with the data of the PCR array. It has been concluded that DNA fragmentation in human spermatozoa can probably change regular events throughout the oviducts. Consequently, the genes of interest may change sperm function and probably its fate in the female reproductive tract.

Pronounced Postmating Response in the Drosophila Female Reproductive Tract Fluid Proteome

Fertility depends on the progression of complex and coordinated postmating processes within the extracellular environment of the female reproductive tract (FRT). Molecular interactions between ejaculate and FRT proteins regulate many of these processes, including sperm motility, migration, storage, and modification, along with concurrent changes in the female. Although extensive progress has been made in the proteomic characterization of the male-derived components of sperm and seminal fluid, investigations into the FRT have remained more limited. To achieve a comparable level of knowledge regarding female-derived proteins that comprise the reproductive environment, we utilized semiquantitative MS-based proteomics to study the composition of the FRT tissue and, separately, the luminal fluid, before and after mating in Drosophila melanogaster. Our approach leveraged whole-fly isotopic labeling to delineate female proteins from transferred male ejaculate proteins. Our results revealed several characteristics that distinguish the FRT fluid proteome from the FRT tissue proteome: (1) the fluid proteome is encoded by genes with higher overall levels of FRT gene expression and tissue specificity, including many genes with enriched expression in the fat body, (2) fluid-biased proteins are enriched for metabolic functions, and (3) the fluid exhibits pronounced postmating compositional changes. The dynamic mating-induced proteomic changes in the FRT fluid inform our understanding of secretory mechanisms of the FRT, serve as a foundation for establishing female contributions to the ejaculate-female interactions that regulate fertility, and highlight the importance of applying proteomic approaches to characterize the composition and dynamics of the FRT environment.

Peroxiredoxin 6 Plays Essential Role in Mediating Fertilization and Early Embryonic Development in Rabbit Oviduct

The oviduct is a site for early reproductive events including gamete maturation, fertilization, and early embryo development. Secretory cells lining the oviduct lumen synthesize and secrete proteins that interact with gametes and developing embryos. Although previous studies have identified some of the secretory proteins in the oviduct, however, knowledge and their precise specific functions in the oviduct are poorly understood. In this study, by using proteomic approach, we identified a secretory protein, Peroxiredoxin 6 (PRDX6), and evaluated its role in mediating early pregnancy events, fertilization, and embryo development in rabbit oviduct. The expression of PRDX6 was significantly higher in ampulla and isthmus sections of the oviduct in mated animal groups compared to non-mated controls. Furthermore, significant reduction in number of embryos recovered from PRDX6 siRNA-transfected oviductal horn was observed compared to the control contralateral horn. Moreover, in animals receiving PRDX6 siRNA in their oviductal horn, the number of implanted blastocysts was significantly less in the uterus as observed on day 9 post-coital (p.c.). Further, during embryo-rabbit oviduct epithelial cell (ROEC) co-culture, siRNA-mediated PRDX6 silencing attenuated the early embryonic development. Mechanistically, increased levels of ROS and expression of oxidative stress- and inflammation-related proteins were found in PRDX6 siRNA-treated ROEC cells as compared to control cells, implicating that ablation of PRDX6 in the oviduct creates a stress-induced micro-environment detrimental to early embryonic development in oviduct. Taken together, our data suggest that PRDX6 maintains an optimal micro-environment conducive to successful embryo development and can be considered as a candidate to evaluate its therapeutic potential in IVF strategies.

In vivo dynamic 3D imaging of oocytes and embryos in the mouse oviduct

Developmental biologists have always relied on imaging to shed light on dynamic cellular events. However, processes such as mammalian fertilization and embryogenesis are generally inaccessible for direct imaging. In consequence, how the oviduct (fallopian tube) facilitates the transport of gametes and preimplantation embryos continues to be unanswered. Here we present a combination of intravital window and optical coherence tomography for dynamic, volumetric, in vivo imaging of oocytes and embryos as they are transported through the mouse oviduct. We observed location-dependent circling, oscillating, and long-distance bi-directional movements of oocytes and embryos that suggest regulatory mechanisms driving transport and question established views in the field. This in vivo imaging approach can be combined with a variety of genetic and pharmacological manipulations for live functional analysis, bringing the potential to investigate reproductive physiology in its native state.

Wang and Larina present in vivo volumetric imaging of oocytes and embryos as they are transported through the mouse oviduct with optical coherence tomography and an intravital microscopy. The study reveals complex dynamics of oocytes and embryos that suggest a regulatory role of cilia and oviductal contractions in driving the transport.

Evidence of haptoglobin in the porcine female genital tract during oestrous cycle and its effect on in vitro embryo production

Recent evidence supports involvement of the acute phase protein haptoglobin in numerous events during mammalian reproduction. The present study represents an in-depth investigation of haptoglobin expression and secretion in the porcine oviduct and uterus, and assesses its effect on porcine in vitro embryo production. A systematic study was made of sows in different oestrous stages: late follicular, early luteal and late luteal stages. Relative haptoglobin mRNA abundance was quantified by RT-qPCR. In addition, expression of the protein was analysed by immunohistochemistry and the results were complemented by Western-blot and proteomic analyses of the oviductal and uterine fluids. In vitro porcine fertilization and embryo culture were carried out in the presence of haptoglobin. The results indicate that haptoglobin mRNA expression in the porcine oviduct and uterus is most abundant during the late luteal stage of the oestrous cycle. By means of Western blot and proteomic analyses haptoglobin presence was demonstrated in the oviduct epithelium and in the oviductal and uterine fluids in different stages of the oestrous cycle. The addition of haptoglobin during gamete co-incubation had no effect on sperm penetration, monospermy or efficiency rates; however, compared with the control group, blastocyst development was significantly improved when haptoglobin was present (haptoglobin: 64.50% vs. control: 37.83%; p < 0.05). In conclusion, the presence of haptoglobin in the oviduct and uterus of sows at different stages of the oestrous cycle suggests that it plays an important role in the reproduction process. The addition of haptoglobin during in vitro embryo production improved the blastocyst rates.

Changes in Oviductal Cells and Small Extracellular Vesicles miRNAs in Pregnant Cows

Early embryonic development occurs in the oviduct, where an ideal microenvironment is provided by the epithelial cells and by the oviductal fluid produced by these cells. The oviductal fluid contains small extracellular vesicles (sEVs), which through their contents, including microRNAs (miRNAs), can ensure proper cell communication between the mother and the embryo. However, little is known about the modulation of miRNAs within oviductal epithelial cells (OECs) and sEVs from the oviductal fluid in pregnant cows. In this study, we evaluate the miRNAs profile in sEVs from the oviductal flushing (OF-sEVs) and OECs from pregnant cows compared to non-pregnant, at 120 h after ovulation induction. In OF-sEVs, eight miRNAs (bta-miR-126-5p, bta-miR-129, bta-miR-140, bta-miR-188, bta-miR-219, bta-miR-345-3p, bta-miR-4523, and bta-miR-760-3p) were up-regulated in pregnant and one miRNA (bta-miR-331-5p) was up-regulated in non-pregnant cows. In OECs, six miRNAs (bta-miR-133b, bta-miR-205, bta-miR-584, bta-miR-551a, bta-miR-1193, and bta-miR-1225-3p) were up-regulated in non-pregnant and none was up-regulated in pregnant cows. Our results suggest that embryonic maternal communication mediated by sEVs initiates in the oviduct, and the passage of gametes and the embryo presence modulate miRNAs contents of sEVs and OECs. Furthermore, we demonstrated the transcriptional levels modulation of selected genes in OECs in pregnant cows. Therefore, the embryonic-maternal crosstalk potentially begins during early embryonic development in the oviduct through the modulation of miRNAs in OECs and sEVs in pregnant cows.

Oviduct fluid extracellular vesicles regulate polyspermy during porcine in vitro fertilisation

High polyspermy is one of the major limitations of porcine invitro fertilisation (IVF). The addition of oviductal fluid (OF) during IVF reduces polyspermy without decreasing the fertilisation rate. Because extracellular vesicles (EVs) have been described as important OF components, the aim of this study was to evaluate the effect of porcine oviductal EVs (poEVs) on IVF efficiency compared with porcine OF (fresh and lyophilised). OF was collected from abattoir oviducts by phosphate-buffered saline flush, and poEVs were isolated by serial ultracentrifugation. Four IVF treatments were conducted: poEVs (0.2mgmL-1), OF (10%), lyophilized and reconstituted pure OF (LOF; 1%) and IVF without supplementation (control). Penetration, monospermy and IVF efficiency were evaluated. Transmission electron microscopy showed an EVs population primarily composed of exosomes (83%; 30-150nm). Supplementation with poEVs during IVF increased monospermy compared with control (44% vs 17%) while maintaining an acceptable penetration rate (61% vs 78% respectively) in a similar way to OF and LOF. Western blotting revealed poEVs proteins involved in early reproductive events, including zona pellucida hardening. In conclusion, our finding show that poEVs are key components of porcine OF and may play roles in porcine fertilisation and polyspermy regulation, suggesting that supplementation with poEVs is a reliable strategy to decrease porcine polyspermy and improve invitro embryo production outcomes.

Tetraspanins, More than Markers of Extracellular Vesicles in Reproduction

The participation of extracellular vesicles in many cellular processes, including reproduction, is unquestionable. Although currently, the tetraspanin proteins found in extracellular vesicles are mostly applied as markers, increasing evidence points to their role in extracellular vesicle biogenesis, cargo selection, cell targeting, and cell uptake under both physiological and pathological conditions. In this review, we bring other insight into the involvement of tetraspanin proteins in extracellular vesicle physiology in mammalian reproduction. We provide knowledge regarding the involvement of extracellular vesicle tetraspanins in these processes in somatic cells. Furthermore, we discuss the future direction towards an understanding of their functions in the tissues and fluids of the mammalian reproductive system in gamete maturation, fertilization, and embryo development; their involvement in mutual cell contact and communication in their complexity.

Influence of metabolic status and genetic merit for fertility on proteomic composition of bovine oviduct fluid†

The oviduct plays a crucial role in fertilization and early embryo development providing the microenvironment for oocyte, spermatozoa, and early embryo. Since dairy cow fertility declined steadily over the last decades, reasons for early embryonic loss have gained increasing interest. Analyzing two animal models, this study aimed to investigate the impact of genetic predisposition for fertility and of metabolic stress on the protein composition of oviduct fluid. A metabolic model comprised maiden Holstein heifers and postpartum lactating (Lact) and non-lactating (Dry) cows, while a genetic model consisted of heifers from the Montbéliarde breed and Holstein heifers with low- and high-fertility index. In a holistic proteomic analysis of oviduct fluid from all groups using nano-liquid chromatography tandem-mass spectrometry analysis and label-free quantification, we were able to identify 1976 proteins, among which 143 showed abundance alterations in the pairwise comparisons within both models. Most differentially abundant proteins were revealed between low fertility Holstein and Montbéliarde (52) in the genetic model and between lactating and maiden Holstein (19) in the metabolic model, demonstrating a substantial effect of genetic predisposition for fertility and metabolic stress on the oviduct fluid proteome. Functional classification of affected proteins revealed actin binding, translation, and immune system processes as prominent gene ontology (GO) clusters. Notably, Actin-related protein 2/3 complex subunit 1B and the three immune system-related proteins SERPIND1 protein, immunoglobulin kappa locus protein, and Alpha-1-acid glycoprotein were affected in both models, suggesting that abundance changes of immune-related proteins in oviduct fluid play an important role for early embryonic loss.

Quantitative proteomic strategies to study reproduction in farm animals: Female reproductive fluids

Reproductive fluids from the female reproductive tract are gaining attention for their potential to support and optimize reproductive processes, including gamete maturation and embryo culture in vitro. Quantitative proteomics is a powerful way to decipher the proteome of reproductive tract fluids and to identify biologically relevant proteins. The present review describes proteomic strategies for analysing female reproductive fluid proteins. In addition, it considers the strategies for the preparation of oviductal, uterine and follicular fluid samples. Finally, it highlights the main results of quantitative proteomic studies, providing insights into the biological processes related to reproductive biology in farm animals. SIGNIFICANCE: Assisted reproductive technologies (ARTs) have become vitally important for farm animal breeding and much effort is going into the optimization and refinement of the techniques. There are also attempts to imitate physiological conditions by adding reproductive fluids or individual fluid proteins to improve in vitro procedures. A detailed knowledge of the reproductive fluid proteomes is indispensable. The present review summarizes the most widely used quantitative proteomic approaches for the analysis of fluids from the female reproductive tract and highlights the potential of quantitative proteomics to delineate reproductive processes and identify candidate proteins for ARTs in farm animals.

Review: Environmental impact on early embryonic development in the bovine species

Assisted reproduction techniques (ARTs) provide access to early stage embryos whose analysis and assessment deliver valuable information. The handling of embryos, including the in vitro production of bovine embryos, is a rapidly evolving area which nonetheless exposes the embryos to unnatural conditions for a period of time. The Fallopian tube provides innumerable quantitative and qualitative factors, all of which guarantee the successful development of the embryo. It is well known that the Fallopian tube can be bypassed, using embryo transfer, resulting in successful implantation in the target recipient animal and the birth of calves. However, the question arises as to whether such circumvention has a negative impact on the embryo during this sensitive development period. First crosstalk between the embryo and its environment confirms mutual recognition activities and indicate bilateral effects. Nowadays, in vitro production of bovine embryos is a well-established technology. However, it is still evident that in vitro generated embryos are not qualitatively comparable to embryos obtained ex vivo. To counteract these differences, comparative studies between in vitro and ex vivo embryos are advantageous, as embryos grown in their physiological environment can provide a blueprint or gold standard against which to compare embryos produced in vitro. Attempts to harness the bovine oviduct were sometimes very invasive and did not result in wide acceptance and routine use. Long-term development and refinement of transvaginal endoscopy for accessing the bovine oviduct has meanwhile been routinely applied for research as well as in practice. Comparative studies combining in vitro development with development in the cattle oviduct revealed that the environmental conditions to which the embryo is exposed before activation of the embryonic genome can have detrimental and lasting effects on its further development. These effects are manifested as deviations in gene expression profiles and methylation signatures as well as frequency of whole chromosomal or segmental aberrations. Furthermore, it was shown that hormonal superstimulation (multiple ovulation and embryo transfer), varying progesterone concentrations as well as metabolic disorders caused by high milk production, markedly affected embryo development in the postpartum period. Assisted reproductive techniques that allow the production and handling of extra numbers of generated embryos promise to have a very high impact on scientific and practical application. Any influence on the early embryonic life, both in animals and in vitro, is accompanied by a sensitive change in embryonic activity and should be assessed in vivo on the basis of physiological conditions before being used for ART.

Spatial and Pregnancy-Related Changes in the Protein, Amino Acid, and Carbohydrate Composition of Bovine Oviduct Fluid

Knowledge of how the biochemical composition of the bovine oviduct is altered due to the oviduct anatomy or the presence of an embryo is lacking. Thus, the aim of this study was to assess the effect of (І) oviduct anatomy and (ІІ) embryo presence on oviductal fluid (OF) protein, amino acid, and carbohydrate composition. Cross-bred beef heifers (n = 19) were synchronized and those in standing estrus were randomly allocated to a cyclic (non-bred) or pregnant (artificially inseminated) group. All heifers were slaughtered on Day 3 after estrus. The oviducts ipsilateral to the corpus luteum from each animal were isolated, straightened and cut, separating ampulla and isthmus. Each portion was flushed with 500 µl of PBS enabling recovery of the oocyte/embryo. Recovered unfertilized oocytes (cyclic group) and embryos (8-cell embryos; pregnant group) were located in the isthmus of the oviduct. Samples of flushing medium from the isthmus and ampulla were used for proteomic (n = 2 per group), amino acid (n = 5), and carbohydrate (n = 5) analysis. For proteomic analysis, total protein from cyclic and pregnant samples were labelled with different cyanine fluorescent probes and separated according to the isoelectric point using immobilized pH gradient strips (pH 3-10, 17 cm, Protean® IEF cell system, Bio Rad). Second dimension was performed in a polyacrylamide gel (12%) in the presence of SDS using a Protean II XL system (Bio Rad). Images were obtained with a Typhoon 9410 scanner and analyzed with Progenesis SameSpots software v 4.0. Amino acid content in the OF was determined by high performance liquid chromatography (HPLC). Glucose, lactate, and pyruvate were quantified using microfluorometric enzyme-linked assays. For the proteomic assessment, the results of the image analysis were compared by ANOVA. For both amino acid and carbohydrate analyses, statistical analysis was carried out by 2-way ANOVA with the Holm-Sidak nonparametric post hoc analysis. On Day 3 post-estrus, OF composition varied based on (І) anatomical region, where isthmic metabolites were present in lower (i.e., lactate, glycine, and alanine) or higher (i.e., arginine) concentrations compared to the ampulla; and (ІІ) embryo presence, which was correlated with greater, arginine, phosphoglycerate kinase 1, serum albumin, α-1-antiproteinase and IGL@ protein concentrations. In conclusion, data indicate that the composition of bovine OF is anatomically dynamic and influenced by the presence of an early embryo.

Composing the Early Embryonic Microenvironment: Physiology and Regulation of Oviductal Secretions

The oviductal fluid is the first environment experienced by mammalian embryos at the very beginning of life. However, it has long been believed that the oviductal environment was not essential for proper embryonic development. Successful establishment of in vitro embryo production techniques (which completely bypass the oviduct) have reinforced this idea. Yet, it became evident that in vitro produced embryos differ markedly from their in vivo counterparts, and these differences are associated with lower pregnancy outcomes and more health issues after birth. Nowadays, researchers consider the oviduct as the most suitable microenvironment for early embryonic development and a substantial effort is made to understand its dynamic, species-specific functions. In this review, we touch on the origin and molecular components of the oviductal fluid in mammals, where recent progress has been made thanks to the wider use of mass spectrometry techniques. Some of the factors and processes known to regulate oviductal secretions, including the embryo itself, as well as ovulation, insemination, endogenous and exogenous hormones, and metabolic and heat stress, are summarized. Special emphasis is laid on farm animals because, owing to the availability of sample material and the economic importance of fertility in livestock husbandry, a large part of the work on this topic has been carried out in domestic animals used for dairy and/or meat production.

Specific trophoblast transcripts transferred by extracellular vesicles affect gene expression in endometrial epithelial cells and may have a role in embryo-maternal crosstalk

Background

Successful establishment of pregnancy hinges on appropriate communication between the embryo and the uterus prior to implantation, but the nature of this communication remains poorly understood. Here, we tested the hypothesis that the endometrium is receptive to embryo-derived signals in the form of RNA.

Methods

We have utilized a non-contact co culture system to simulate the conditions of pre implantation environment of the uterus. We bioorthogonally tagged embryonic RNA and tracked the transferred transcripts to endometrium. Transferred transcripts were separated from endometrial transcripts and sequenced. Changes in endometrial transcripts were quantified using quantitative PCR.

Results

We show that three specific transcripts are transferred to endometrial cells. We subsequently demonstrate a role of extracellular vesicles (EVs) in this process, as EVs obtained from cultured trophoblast spheroids incubated with endometrial cells induced down-regulation of all the three identified transcripts in endometrial cells.

Finally, we show that EVs/nanoparticles captured from conditioned culture media of viable embryos as opposed to degenerating embryos induce ZNF81 down-regulation in endometrial cells, hinting at the functional importance of this intercellular communication.

Conclusion

Ultimately, our findings demonstrate the existence of an RNA-based communication which may be of critical importance for the establishment of pregnancy.

The human endosalpinx: anatomical three-dimensional study and reconstruction using confocal microtomography

Purpose

To evaluate in three dimensions (3D) the human endosalpinx and reconstruct its surface along its different anatomical segments, without the injection or insertion of luminal contrasts, using confocal microtomography (micro-CT).

Material and methods

15 fallopian tubes (FT) from 14 women in reproductive age from procedures for benign disease or sterilization were selected. The specimens were fixed in formalin and stained with Lugol solution. Micro-CT studies were conducted on the specimens using protocols adapted from biological studies, to acquire images to reconstruct in 3D the endosalpinx surface.

Results

From these specimens, 6 presented the intra-mural segment, 14 presented the isthmus and 15 presented the ampulla and fimbria segment of the FT. The specimen presented tissue definition, and contrast sufficient for FT endosalpinx morphological analysis and lumen definition. The intramural portion presented initially a mucosal projection toward the lumen, bending on its own axis, and increased numbers of projections towards the isthmic portion, where the projections become longer more numerous. The endosalpinx becomes more tortuous, the lumen diameter increases and the mucosal projections become more bulky in the ampullary portion, with the projections less present on the antimesenteric side. The infundibular portion is marked with the organized and predictable endosalpinx, the abdominal ostium is cleared demonstrated, with the reduction of the endosalpinx volume. The fimbria demonstrated a small relation between fringes and intratubal endosalpinx.

Conclusions

Microscopic anatomy of different segments of the human FT mucosa can be analyzed and reconstructed in 3D with histological correlation using micro-CT.

The human tubal lavage proteome reveals biological processes that may govern the pathology of hydrosalpinx

Hydrosalpinx, the blockage of fallopian tubes, can result from pelvic inflammatory disease. Hydrosalpinx is a cause of infertility and negatively impacts in vitro fertilization. To better understand the pathobiology of hydrosalpinx, we compared the proteome of lavages from disease vs. healthy fallopian tubes. Results indicate a disruption of redox homeostasis and activation of the complement system, immune cell infiltration, and phagocytosis; pathways that may drive tubal injury. To our surprise among the most prominent proteins with hydrosalpinx was mesothelin (MSLN), which until now has only been associated with epithelial malignancies. Analogous to mesothelioma and ovarian carcinoma, a significant increase of MSLN was detected in plasma from patients with hydrosalpinx. This finding suggests MSLN may provide clinical diagnosis in lieu of the current approaches that require invasive imaging. Importantly, these findings implicate MSLN in a benign disease, indicating that the activation and role of MSLN is not restricted to cancer.

Extracellular Vesicles in the Oviduct: Progress, Challenges and Implications for the Reproductive Success

The oviduct is the anatomical part of the female reproductive tract where the early reproductive events take place, from gamete transport, fertilization and early embryo development to the delivery of a competent embryo to the uterus, which can implant and develop to term. The success of all these events rely upon a two-way dialogue between the oviduct (lining epithelium and secretions) and the gametes/embryo(s). Recently, extracellular vesicles (EVs) have been identified as major components of oviductal secretions and pointed to as mediators of the gamete/embryo-maternal interactions. EVs, comprising exosomes and microvesicles, have emerged as important agents of cell-to-cell communication by the transfer of biomolecules (i.e., mRNAs, miRNAs, proteins) that can modulate the activities of recipient cells. Here, we provide the current knowledge of EVs in the oviductal environment, from isolation to characterization, and a description of the EVs molecular content and associated functional aspects in different species. The potential role of oviductal EVs (oEVs) as modulators of gamete/embryo-oviduct interactions and their implications in the success of early reproductive events is addressed. Lastly, we discuss current challenges and future directions towards the potential application of oEVs as therapeutic vectors to improve pregnancy disorders, infertility problems and increase the success of assisted reproductive technologies.

A novel approach to study the bovine oviductal fluid proteome using transvaginal endoscopy

The oviduct provides the optimal micro milieu for early embryo development. However, accessing the bovine oviductal fluid in vivo for analysis is still challenging and therefore the oviductal fluid is usually collected post mortem. In the study presented here we introduce a novel approach to gain minimal invasive access to the bovine oviductal fluid proteome in vivo by transvaginal endoscopy at different stages of the estrous cycle. The first experiment aimed at transferring C4 derivatised magnetic beads to bind the oviductal fluid proteome in situ. Protein carrying beads were recovered by flushing the oviduct and proteins were eluted. In the second experiment a flushing solution was injected into and aspirated from the oviduct repeatedly. The flushing solution was centrifuged to separate the fluid from the cellular debris. Proteins were identified by nano-LC-MS/MS. Two different stages of the estrous cycle (Day 1 and Day 3) were analyzed in samples from 30 heifers. Both methods were applied successfully and in total, more than 3000 proteins were identified, so far representing the most comprehensive OF proteome published. This new minimal invasive approach to access the bovine oviductal fluid proteome facilitates future innovative experimental designs to study the role of the oviductal micro environment during early embryo development.

Sex hormones alter the response of Toll-like receptor 3 to its specific ligand in fallopian tube epithelial cells

Objective

The fallopian tubes play a critical role in the early events of fertilization. The rapid innate immune defense is an important part of the fallopian tubes. Toll-like receptor 3 (TLR3), as a part of the innate immune system, plays an important role in detecting viral infections. In this basic and experimental study, the effect of sex hormones on the function of TLR3 in the OE-E6/E7 cell line was investigated.

Methods

The functionality of TLR3 in this cell line was evaluated by cytokine measurements (interleukin [IL]-6 and IL-1b) and the effects of sex hormones on TLR3 were tested by an enzyme-linked immunosorbent assay kit. Additionally, TLR3 small interfering RNA (siRNA) and a TLR3 function-blocking antibody were used to confirm our findings.

Results

The production of IL-6 significantly increased in the presence of polyinosinic-polycytidylic acid (poly(I:C)) as the TLR3 ligand. Using a TLR3-siRNA-ransfected OE-E6/E7 cell line and function-blocking antibody confirmed that cytokine production was due to TLR3. In addition, 17-β estradiol and progesterone suppressed the production of IL-6 in the presence and absence of poly(I:C).

Conclusion

These results imply that sex hormones exerted a suppressive effect on the function of TLR3 in the fallopian tube cell line when different concentrations of sex hormones were present. The current results also suggest that estrogen receptor beta and nuclear progesterone receptor B are likely to mediate the hormonal regulation of TLR3, as these two receptors are the main estrogen and progesterone receptors in OE-E6/E7 cell line.

Genes Encoding Mammalian Oviductal Proteins Involved in Fertilization are Subjected to Gene Death and Positive Selection

Oviductal proteins play an important role in mammalian fertilization, as proteins from seminal fluid. However, in contrast with the latter, their phylogenetic evolution has been poorly studied. Our objective was to study in 16 mammals the evolution of 16 genes that encode oviductal proteins involved in at least one of the following steps: (1) sperm–oviduct interaction, (2) acrosome reaction, and/or (3) sperm–zona pellucida interaction. Most genes were present in all studied mammals. However, some genes were lost along the evolution of mammals and found as pseudogenes: annexin A5 (ANXA5) and deleted in malignant brain tumor 1 (DMBT1) in tarsier; oviductin (OVGP1) in megabat; and probably progestagen-associated endometrial protein (PAEP) in tarsier, mouse, rat, rabbit, dolphin, and megabat; prostaglandin D2 synthase (PTGDS) in microbat; and plasminogen (PLG) in megabat. Four genes [ANXA1, ANXA4, ANXA5, and heat shock 70 kDa protein 5 (HSPA5)] showed branch-site positive selection, whereas for seven genes [ANXA2, lactotransferrin (LTF), OVGP1, PLG, S100 calcium-binding protein A11 (S100A11), Sperm adhesion molecule 1 (SPAM1), and osteopontin (SPP1)] branch-site model and model-site positive selection were observed. These results strongly suggest that genes encoding oviductal proteins that are known to be important for gamete fertilization are subjected to positive selection during evolution, as numerous genes encoding proteins from mammalian seminal fluid. This suggests that such a rapid evolution may have as a consequence that two isolated populations become separate species more rapidly.

Extracellular cell stress (heat shock) proteins-immune responses and disease: an overview

Extracellular cell stress proteins are highly conserved phylogenetically and have been shown to act as powerful signalling agonists and receptors for selected ligands in several different settings. They also act as immunostimulatory 'danger signals' for the innate and adaptive immune systems. Other studies have shown that cell stress proteins and the induction of immune reactivity to self-cell stress proteins can attenuate disease processes. Some proteins (e.g. Hsp60, Hsp70, gp96) exhibit both inflammatory and anti-inflammatory properties, depending on the context in which they encounter responding immune cells. The burgeoning literature reporting the presence of stress proteins in a range of biological fluids in healthy individuals/non-diseased settings, the association of extracellular stress protein levels with a plethora of clinical and pathological conditions and the selective expression of a membrane form of Hsp70 on cancer cells now supports the concept that extracellular cell stress proteins are involved in maintaining/regulating organismal homeostasis and in disease processes and phenotype. Cell stress proteins, therefore, form a biologically complex extracellular cell stress protein network having diverse biological, homeostatic and immunomodulatory properties, the understanding of which offers exciting opportunities for delivering novel approaches to predict, identify, diagnose, manage and treat disease.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

Influence of elevated temperature on bovine oviduct epithelial cells (BOECs)

The aim of this study was to evaluate the influence of elevated temperature on bovine oviduct epithelial cells (BOECs), based on the expression and localization of both heat shock protein 70 (HSP70), responsible for the cellular defence mechanism, and oviduct specific glycoprotein 1 (OVGP1) which is the most important embryotrophic protein. BOECs were cultured alone and co-cultured with cattle embryos at control (38.5°C) and elevated temperature (41°C) for 168 h. The elevated temperature had no effect on the viability of BOECs but exerted a negative effect on embryo development. The elevated temperature increased the expression of HSP70 and decreased the expression of OVGP1 at both mRNA and protein levels in BOECs cultured alone and those co-cultured with embryos. However, the presence of embryos limited the decrease in OVGP1 expression in BOECs at elevated temperature but did not alter the expression of HSP70. These results demonstrate for the first time the influence of elevated temperature on BOECs, consequently providing insights into the interactions between the embryo and the oviduct at elevated temperature.

Proteome of the periovulatory oviduct and uterus of goats as related to nutritional balance

This study was conducted to evaluate the effects of different feeding levels on the proteome of oviduct and uterus tissues of hormonally stimulated goats during the periovulatory period. Forty goats were separated into four different diet groups: Diet 1.0 M (n = 11), Diet 1.3 M (n = 10), Diet 1.6 M (n = 9), Diet 1.9 M (n = 10), fed with 1.0, 1.3, 1.6 and 1.9 times live weight maintenance, respectively. After four weeks of treatment, six hormonally stimulated females per treatment group were randomly selected for collection of uterine and the oviduct tissue samples. Samples were collected after animals were slaughtered in a commercial unit. Feeding goats with 1.3 to 1.9 times more nutrients than a control group directly influenced the proteome of the oviduct and uterus, altering the expression of proteins that participate in biological processes such as apoptosis, antioxidant, and immunological activities. These events are crucial for fertilization and early embryonic survival. Expression of oviduct proteins such as Tubulin Beta 2B, Transferrin and Disulphide-isomerase A3 increased in the 1.9 M group in relation to the other feeding levels. Disulphide-isomerase A4 showed higher expression in the 1.0 M group compared to diets with higher energetic levels. As energy intake increased in the diets, there was higher expression of Alpha-1-antitrypsin and downregulation of Profilin-1 in the uterus of the goats. In conclusion, this study showed that specific proteins of the goat oviduct and uterus expressed during the periovulatory period are modified as the result of nutritional balance.

Prolonged in vivo functional assessment of the mouse oviduct using optical coherence tomography through a dorsal imaging window

The oviduct (or fallopian tube) serves as an environment for gamete transport, fertilization and preimplantation embryo development in mammals. Although there has been increasing evidence linking infertility with disrupted oviduct function, the specific roles that the oviduct plays in both normal and impaired reproductive processes remain unclear. The mouse is an important mammalian model to study human reproduction. However, most of the current analyses of the mouse oviduct rely on static histology or 2D visualization, and are unable to provide dynamic and volumetric characterization of this organ. The lack of imaging access prevents longitudinal live analysis of the oviduct and its associated reproductive events, limiting the understanding of mechanistic aspects of fertilization and preimplantation pregnancy. To address this limitation, we report a 3D imaging approach that enables prolonged functional assessment of the mouse oviduct in vivo. By combining optical coherence tomography with a dorsal imaging window, this method allows for extended volumetric visualization of the oviduct dynamics, which was previously not achievable. The approach is used for quantitative analysis of oviduct contraction, spatiotemporal characterization of cilia beat frequency and longitudinal imaging. This new approach is a useful in vivo imaging platform for a variety of live studies in mammalian reproduction.

Steroids affect gene expression, ciliary activity, glucose uptake, progesterone receptor expression and immunoreactive steroidogenic protein expression in equine oviduct explants in vitro

The oviduct undergoes dramatic functional and morphological changes throughout the oestrous cycle of the mare. To unravel the effects of steroids on the morphology, functionality and gene expression of the equine oviduct, an in vitro oviduct explant culture system was stimulated with physiological concentrations of progesterone and 17β-oestradiol. Four conditions were compared: unsupplemented preovulatory explants, preovulatory explants that were stimulated with postovulatory hormone concentrations, unsupplemented postovulatory explants and postovulatory explants that were stimulated with preovulatory hormone concentrations. The modulating effects of both steroids on oviduct explants were investigated and the following parameters examined: (1) ciliary activity, (2) glucose consumption and lactate production pattern, (3) ultrastructure, (4) mRNA expression of embryotrophic genes, (5) steroidogenic capacities of oviductal explants and (6) progesterone receptor expression. The present paper shows that the equine oviduct is an organ with potential steroidogenic capacities, which is highly responsive to local changes in progesterone and 17β-oestradiol concentrations at the level of morphology, functionality and gene expression of the oviduct. These data provide a basis to study the importance of endocrine and paracrine signalling during early embryonic development in the horse.

Review: The epic journey of sperm through the female reproductive tract

Millions or billions of sperm are deposited by artificial insemination or natural mating into the cow reproductive tract but only a few arrive at the site of fertilization and only one fertilizes an oocyte. The remarkable journey that successful sperm take to reach an oocyte is long and tortuous, and includes movement through viscous fluid, avoiding dead ends and hostile immune cells. The privileged collection of sperm that complete this journey must pass selection steps in the vagina, cervix, uterus, utero-tubal junction and oviduct. In many locations in the female reproductive tract, sperm interact with the epithelium and the luminal fluid, which can affect sperm motility and function. Sperm must also be tolerated by the immune system of the female for an adequate time to allow fertilization to occur. This review emphasizes literature about cattle but also includes work in other species that emphasizes critical broad concepts. Although all parts of the female reproductive tract are reviewed, particular attention is given to the sperm destination, the oviduct.

Identification by proteomics of oviductal sperm-interacting proteins

The interactions between oviductal fluid (OF) proteins and spermatozoa play major roles in sperm selection, storage and capacitation before fertilization. However, only a few sperm-interacting proteins in the OF has been identified and very little is known about the regulation of sperm-oviduct interactions across the estrous cycle. Samples of bovine frozen-thawed sperm from three bulls were incubated with OF at pre-, post-ovulatory stages (Pre-/Post-ov) or luteal phase (LP) of the estrous cycle (7 mg/mL proteins, treated groups) or with a protein-free media (control). The proteomes of sperm cells were assessed by nanoLC-MS/MS and quantified by label-free methods. A total of 27 sperm-interacting proteins originating in the OF were identified. Among those, 14 were detected at all stages, eight at Post-ov and LP and five only at LP. The sperm-interacting proteins detected at all stages or at LP and Post-ov were on average more abundant at LP than at other stages (P < 0.05). At Pre-ov, OVGP1 was the most abundant sperm-interacting protein while at Post-ov, ACTB, HSP27, MYH9, MYH14 and OVGP1 were predominant. Different patterns of abundance of sperm-interacting proteins related to the stage were evidenced, which greatly differed from those previously reported in the bovine OF. In conclusion, this study highlights the important regulations of sperm-oviduct interactions across the estrous cycle and provides new protein candidates that may modulate sperm functions.

The role of mating in oviduct biology

The oviduct connects the ovary to the uterus, and is subject to changes that influence gamete transport, fertilization, and early embryo development. The ovarian steroids estradiol and progesterone are largely responsible for regulating oviduct function, although mating signals also affect the female reproductive tract, both indirectly, through sensory stimulation, and directly, through contact with seminal plasma or spermatozoa. The resulting alterations in gene and protein expression help establish a microenvironment that is appropriate for sperm storage and selection, embryo development, and gamete transport. Mating may also induce the switch from a non-genomic to a genomic pathway of estradiol-accelerated oviduct egg transport, reflecting a novel example of the functional plasticity in well-differentiated cells. This review highlights the physiological relevance of various aspects of mating to oviduct biology and reproductive success. Expanding our knowledge of the mating-associated molecular and cellular events in oviduct cells would undoubtedly facilitate new therapeutic strategies to treat infertility attributable to oviduct pathologies. Mol. Reprod. Dev. 83: 875-883, 2016 © 2016 Wiley Periodicals, Inc.

Introduction: A Brief Guide to the Periconception Environment

Definition of the periconception period is not an exact science and is probably somewhat arbitrary. One can define it as spanning the period from the final stages of gamete maturation until formation of the embryo and the stages of embryonic development and implantation. Hence, the periconception period includes periods when spermatozoa are in the female reproductive tract, oocytes are matured and ovulated into the oviduct, fertilization occurs and the embryo undergoes development. By definition the implantation process and the early stages of placenta formation are also regarded as a part of the periconception period. In this article we highlight a few of the major advances which have transformed this topic over the last two decades. It is now clear that the fitness and wellbeing of developing mammalian embryos, including the human, are highly dependent on the health status, diet and habits of both parents especially in the months and weeks that precede the formation of oocytes and spermatozoa.

Profiling of proteins secreted in the bovine oviduct reveals diverse functions of this luminal microenvironment

The oviductal microenvironment is a site for key events that involve gamete maturation, fertilization and early embryo development. Secretions into the oviductal lumen by either the lining epithelium or by transudation of plasma constituents are known to contain elements conducive for reproductive success. Although previous studies have identified some of these factors involved in reproduction, knowledge of secreted proteins in the oviductal fluid remains rudimentary with limited definition of function even in extensively studied species like cattle. In this study, we used a shotgun proteomics approach followed by bioinformatics sequence prediction to identify secreted proteins present in the bovine oviductal fluid (ex vivo) and secretions from the bovine oviductal epithelial cells (in vitro). From a total of 2087 proteins identified, 266 proteins could be classified as secreted, 109 (41%) of which were common for both in vivo and in vitro conditions. Pathway analysis indicated different classes of proteins that included growth factors, metabolic regulators, immune modulators, enzymes, and extracellular matrix components. Functional analysis revealed mechanisms in the oviductal lumen linked to immune homeostasis, gamete maturation, fertilization and early embryo development. These results point to several novel components that work together with known elements mediating functional homeostasis, and highlight the diversity of machinery associated with oviductal physiology and early events in cattle fertility.

N-glycoproteomic analysis of human follicular fluid during natural and stimulated cycles in patients undergoing in vitro fertilization

OBJECTIVE

Hyperstimulation methods are broadly used for in vitro fertilization (IVF) in patients with infertility; however, the side effects associated with these therapies, such as ovarian hyperstimulation syndrome (OHSS), have not been well studied. N-glycoproteomes are subproteomes used for the remote sensing of ovarian stimulation in follicular growth. Glycoproteomic variation in human follicular fluid (hFF) has not been evaluated. In this study, we aimed to identify and quantify the glycoproteomes and N-glycoproteins (N-GPs) in natural and stimulated hFF using label-free nano-liquid chromatography/electrospray ionization-quad time-of-flight mass spectrometry.

METHODS

For profiling of the total proteome and glycoproteome, pooled protein samples from natural and stimulated hFF samples were selectively isolated using hydrazide chemistry to obtain the total proteomes and glycoproteomes. N-GPs were validated by the consensus sequence N-X-S/T (92.2% specificity for the N-glycomotif at p<0.05). All data were compared between natural versus hyperstimulated hFF samples.

RESULTS

We detected 41 and 44 N-GPs in the natural and stimulated hFF samples, respectively. Importantly, we identified 11 N-GPs with greater than two-fold upregulation in stimulated hFF samples compared to natural hFF samples. We also validated the novel N-GPs thyroxine-binding globulin, vitamin D-binding protein, and complement proteins C3 and C9.

CONCLUSION

We identified and classified N-GPs in hFF to improve our understanding of follicular physiology in patients requiring assisted reproduction. Our results provided important insights into the prevention of hyperstimulation side effects, such as OHSS.

Lactadherin is a candidate oviduct Lewis X trisaccharide receptor on porcine spermatozoa

A recent study has demonstrated that porcine spermatozoa recognize with high affinity carbohydrate structures containing Lewis X motifs. Sperm adhesion to Lewis X is proposed to mediate sperm binding to the oviduct epithelium to form a reservoir. The objective of this study was to identify Lewis X-binding proteins from porcine spermatozoa as candidate receptors for oviduct glycans. To identify low-abundance proteins typically masked by proteins originating from seminal fluid, Lewis X candidate receptors were enriched from cauda epididymal boar spermatozoa. Plasma membrane preparations from cauda epididymal spermatozoa were subjected to RP-HPLC and glycan blotting assays to isolate and detect proteins that bind Lewis X. Following bottom-up LC-MS/MS analysis, among the two bands that bound sulfated Lewis X, ADAM5, which spermatozoa, was confidently identified. ADAM family members have been established as contributors to sperm entry into the oviduct. A second sulfated Lewis X-binding protein identified was the peripheral membrane protein lactadherin (also known as P47, SED1 and MFG-E8 in different species). The interaction between Lewis X and lactadherin was functionally important because competitive inhibition by soluble recombinant lactadherin reduced sperm binding to the oviduct epithelium. Furthermore, far-western blotting demonstrated that purified lactadherin could bind oviduct cells. In summary, these findings reveal that, in addition to the previously reported glycan affinity of accessory gland proteins that adhere to spermatozoa, multiple proteins intrinsic to spermatozoa have affinity for a specific oviduct glycan. Further, in addition to binding to the zona pellucida, lactadherin is now implicated in binding to oviduct glycans to promote formation of the sperm reservoir.

Proteome of equine oviducal fluid: effects of ovulation and pregnancy

The equine oviduct plays a pivotal role in providing the optimal microenvironment for early embryonic development, but little is known about the protein composition of the oviducal fluid in the horse. The aim of the present study was to provide a large-scale identification of proteins in equine oviducal fluid and to determine the effects of ovulation and pregnancy. Four days after ovulation, the oviducts ipsilateral and contralateral to the ovulation side were collected from five pregnant and five non-pregnant mares. Identification and relative quantification of proteins in the oviducal fluid of the four groups was achieved by isobaric tags for relative and absolute quantification (iTRAQ) labelling and HPLC–tandem mass spectrometry. The presence of an embryo in the ipsilateral oviducal fluid of pregnant mares induced upregulation of 11 and downregulation of two proteins compared with the contralateral side, and upregulation of 19 proteins compared with the ipsilateral side of non-pregnant mares. Several of these upregulated proteins are related to early pregnancy in other species. The present study represents the first high-throughput identification of proteins in the oviducal fluid of the mare. The results support the hypothesis that the equine embryo interacts with the oviduct, affecting the maternal secretion pattern of proteins involved in pregnancy-related pathways.

Oviduct: roles in fertilization and early embryo development

Animal oviducts and human Fallopian tubes are a part of the female reproductive tract that hosts fertilization and pre-implantation development of the embryo. With an increasing understanding of roles of the oviduct at the cellular and molecular levels, current research signifies the importance of the oviduct on naturally conceived fertilization and pre-implantation embryo development. This review highlights the physiological conditions within the oviduct during fertilization, environmental regulation, oviductal fluid composition and its role in protecting embryos and supplying nutrients. Finally, the review compares different aspects of naturally occurring fertilization and assisted reproductive technology (ART)-achieved fertilization and embryo development, giving insight into potential areas for improvement in this technology.

Differential gene expression in porcine oviduct during the oestrous cycle

The oviduct undergoes changes under the influence of steroid hormones during the oestrous cycle. However, the molecular mechanisms underlying oviductal regulation are not fully understood. The aim of the present study was to identify the gene expression profile of the porcine oviduct in different stages of the cycle using microarray technology. A systematic study was performed on animals at four different stage: prepubertal gilts, and sows in the preovulatory, postovulatory and luteal phase of the oestrous cycle. The porcine oviduct expressed a total of 4929 genes. Moreover, significant differences in the expression of several genes were detected as the oestrous cycle progressed. Analysis of the differentially expressed genes indicated that a total of 86, 89 and 15 genes were upregulated in prepubertal gilts, preovulatory and luteal sows respectively compared with levels observed in postovulatory sows. Moreover, 80, 51 and 64 genes were downregulated in prepubertal, preovulatory and luteal animals respectively compared with the postovulatory sows. The concentrations of 10 selected transcripts were quantified by real-time reverse transcription–polymerase chain reaction to validate the cDNA array hybridisation data. Conversely, for some genes, localisation of corresponding protein expression in the oviduct was analysed by immunohistochemistry (i.e. cholecystokinin, glutathione peroxidase 2, mucin 1, phosphatidylethanolamine binding protein 4 and tachykinin 3) and mass spectrometry analysis of oviductal fluid allowed identification of peptides from all five proteins. The results of the present study demonstrate that gene expression in the porcine oviduct is clearly regulated during the oestrous cycle, with some oviductal proteins that could be related to several reproductive processes described here for the first time.

Roles of Grp78 in Female Mammalian Reproduction

The glucose-regulated protein (GRP78) also referred to as immunoglobulin heavy chain binding protein (Bip) is one of the best characterized endoplasmic reticulum (ER) chaperone proteins, which belongs to the heat-shock protein (HSP) family. GRP78 as a central regulator of ER stress (ERS) plays many important roles in cell survival and apoptosis through controlling the activation of transmembrane ERS sensors: PKR-like ER-associated kinase (PERK), inositol requiring kinase 1 (IRE1), and activating transcription factor 6 (ATF6). Many studies have reported that GRP78 is involved in the physiological and pathological process in female reproduction, including follicular development, corpus luteum (CL), oviduct, uterus, embryo, preimplantation development, implantation/decidualization, and the placenta. The present review summarizes the biological or pathological roles and signaling mechanisms of GRP78 during the reproductive processes. Further study on the functions and mechanisms of GRP78 may provide new insight into mammalian reproduction, which not only enhance the understanding of the physiological roles but also support therapy target against infertility.

Regulation of the bovine oviductal fluid proteome

Our objective was to investigate the regulation of the proteome in the bovine oviductal fluid according to the stage of the oestrous cycle, to the side relative to ovulation and to local concentrations of steroid hormones. Luminal fluid samples from both oviducts were collected at four stages of the oestrous cycle: pre-ovulatory (Pre-ov), post-ovulatory (Post-ov), and mid- and late luteal phases from adult cyclic cows (18–25 cows/stage). The proteomes were assessed by nanoLC–MS/MS and quantified by label-free method. Totally, 482 proteins were identified including a limited number of proteins specific to one stage or one side. Proportions of differentially abundant proteins fluctuated from 10 to 24% between sides at one stage and from 4 to 20% among stages in a given side of ovulation. In oviductal fluids ipsilateral to ovulation, Annexin A1 was the most abundant protein at Pre-ov compared with Post-ov while numerous heat shock proteins were more abundant at Post-ov compared with Pre-ov. Among differentially abundant proteins, seven tended to be correlated with intra-oviductal concentrations of progesterone. A wide range of biological processes was evidenced for differentially abundant proteins, of which metabolic and cellular processes were predominant. This work identifies numerous new candidate proteins potentially interacting with the oocyte, spermatozoa and embryo to modulate fertilization and early embryo development.

Oviductal response to gametes and early embryos in mammals

The oviduct is a complex and organized thin tubular structure connecting the ovary with the uterus. It is the site of final sperm capacitation, oocyte fertilization and, in most species, the first 3–4days of early embryo development. The oviductal epithelium is made up of ciliary and secretory cells responsible for the secretion of proteins and other factors which contribute to the formation of the oviductal fluid. Despite significant research, most of the pathways and oviductal factors implicated in the crosstalk between gametes/early embryo and the oviduct remain unknown. Therefore, studying the oviductal environment is crucial to improve our understanding of the regulatory mechanisms controlling fertilization and embryo development. In vitro systems are a valuable tool to study in vivo pathways and mechanisms, particularly those in the oviducts which in livestock species are challenging to access. In studies of gamete and embryo interaction with the reproductive tract, oviductal epithelial cells, oviductal fluid and microvesicles co-cultured with gametes/embryos represent the most appropriate in vitro models to mimic the physiological conditions in vivo.

Tribbles role in reproduction

Tribbles (TRIB) proteins, a family of evolutionary conserved psuedokinase proteins, modulate various signalling pathways within the cell. The regulatory roles of TRIB make them an important part of a number of biological processes ranging from cell proliferation to metabolism, immunity, inflammation and carcinogenesis. Innate immune system plays a pivotal role during the regulation of reproductive processes that allows successful creation of an offspring. Its involvement initiates from fertilization of the oocyte by spermatozoon and lasts throughout early embryonic development, pregnancy and labour. Therefore, there is a close cooperation between the reproductive system and the innate immune system. Evidence from our lab has demonstrated that improper activation of the innate immune system can reduce embryo implantation, thus leading to infertility. Therefore, control mechanisms regulating the innate immune system function can be critical for successful reproductive events.