Development of ovarian hyperstimulation syndrome: interrogation of key proteins and biological processes in human follicular fluid of women undergoing in vitro fertilization

Obesity-related alterations in protein expression in human follicular fluid from women undergoing in vitro fertilization

OBJECTIVE

To compare the proteomic composition of follicular fluid from women with normal weight vs. women with obesity but without a history of polycystic ovary syndrome or known ovarian dysfunction undergoing in vitro fertilization.

DESIGN

Cross-sectional.

SETTING

Academic medical center.

PATIENT(S)

Eight women with normal weight and 8 women with obesity undergoing in vitro fertilization and without a history of polycystic ovary syndrome, ovulatory dysfunction, diminished ovarian reserve, or known endometriosis were included in the analysis.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Proteomic assessment using liquid chromatography-mass spectrometry analysis.

RESULT(S)

The mean age of women with normal weight was similar to that of women with obesity (32.9 vs. 32.6 years, not significant). The mean body mass index of women with normal weight was 21.2 kg/m² compared with a body mass index of 37.1 kg/m² in women with obesity. A total of 1,174 proteins were identified with ≥2 peptides present. Twenty-five proteins were found to be significantly altered in the follicular fluid from women with obesity. Of these 25 proteins, 19 were up-regulated and 6 were down-regulated. Notably, C-reactive protein was 11-fold higher in the follicular fluid from women with obesity than in the follicular fluid from women with normal weight.

CONCLUSION(S)

Obesity is associated with dysregulation at the level of the follicle, including alterations in proteins related to inflammation and metabolism. These include proteins with emerging roles in energy homeostasis and follicular regulation.

Characterization of altered microRNAs related to different phenotypes of polycystic ovarian syndrome (PCOS) in serum, follicular fluid, and cumulus cells

OBJECTIVE

Polycystic ovarian syndrome (PCOS) is a metabolic syndrome in which steroidogenesis, folliculogenesis, and cellular adhesion play crucial roles in its prognosis. These pathways are controlled and regulated by some small non-coding RNAs called microRNAs (miRs). Several miRs have differential expression in PCOS compared to healthy women, and their dysregulation suggests important roles of miRs in PCOS pathophysiology. However, the role of miRs is still unclear, especially in various phenotypes of PCOS.

MATERIALS AND METHODS

This study was conducted to evaluate the diagnostic potential of miR-212-3p, miR-490-5p, miR-647, and miR-4643 in different subtypes of PCOS. Accordingly, nineteen PCOS patients with different subtypes based on Rotterdam criteria (A: 8, B: not detected in this study, C: 5, and D: 6 patients) and six control age and BMI matched women under ICSI treatment were selected. The relative expression of miRs was then measured in blood serum before hormonal treatment (S1) and before ovum pickup (S2), follicular fluid (FF), and cumulus cells (CC) in all subjects. Also, the expression of miRs predicted target genes (AMH, AR, CYP11A1, CYP17A1, CYP19A1, GDF9, and HSD17B12) were done in the CC of understudy groups.

RESULTS

In general, the results indicated that PCOS significantly increased the expression of miR-212-3p, miR-490-5p, and miR-4643 in FF and CCs compared to control. Although these miRs tend to increase in serum 1 of the PCOS patients, the differences were insignificant. However, there was a significant reduction in the expression of miR-647 in FF and CCs between PCOS vs. control. In addition, the miRs had significantly different expressions in various phenotypes of PCOS. For example, high levels of miR-647 in S2 and low levels of miR-490 in FF and miR-212 in CC can differentiate phenotype A from the other. Also, upregulation of miR-212 in FF and miR-4643 in S1 and low levels of this miR in FF can specifically differentiate subtype A from D. On the other hand, high levels of miR-4643 in FF and miR-490 in CC and lower titter of miR-647 can distinguish subtype C from the other. On the other hand, high levels of AMH, AR, CYP11, CYP17, and HSD17 in the hyperandrogenic PCOS and upregulation of CYP19A1 in the hypoandrogenic group can validate the role of selected miRs in the prognosis of PCOS.

CONCLUSION

Characterization of altered microRNAs in serum, FF, and CCs and their targets in CC showed that the miRs might play critical roles in steroidogenesis and folliculogenesis. These miRs may be used for molecular classification of PCOS subtypes and as biomarkers for PCOS diagnosis.

Proteomic Analysis of Human Follicular Fluid Reveals the Pharmacological Mechanisms of the Chinese Patent Drug Kunling Pill for Improving Diminished Ovarian Reserve

Objective. To explore the pharmacological mechanism of a Chinese patent drug (Kunling Pill (KLP)) on improving diminished ovarian reserve based on proteomic analysis. Methods. A total of 18 patients divided into three groups (the normal ovary reserve (NOR), diminished ovary reserve (DOR), and KLP groups) undergoing assisted reproductive technology by standard ovarian stimulation protocols were recruited to collect follicular fluid. Data-independent acquisition mass spectrometry was used to identify differentially expressed proteins by nano-LC-MS/MS. Bioinformatic analysis was conducted to predict the functions and pathways of the identified proteins. Clinical, hormonal, and biochemical parameters were also analyzed in the three groups. Results. A total of 144 differentially expressed proteins were screened out, including 56 proteins that were downregulated and 88 proteins that were upregulated in the DOR group compared with the NOR group, while 27 proteins were shared in the KLP-treated group. Among them, 10 proteins were upregulated and 17 proteins were downregulated in the KLP-treated group compared with the DOR group. The most enriched biological processes accounted for 28 GO terms, including cellular process, biological regulation, metabolic process, and regulation of biological process. Significant pathways were associated with fatty acid elongation, fatty acid degradation, fatty acid metabolism, nicotinate and nicotinamide metabolism, and valine, leucine, and isoleucine degradation. Conclusion. Our study provides the proteome profiles of human follicular fluid from DOR patients treated by KLP. Functional analyses of proteome datasets revealed that core proteins (SAA1, MIF, and PRDX5) and related pathways (fatty acid metabolism, nicotinate and nicotinamide metabolism, and tyrosine and purine metabolism) are possible pharmacological mechanisms through which KLP improves DOR. Therefore, these findings may help better understand the complex mechanisms through which DOR is treated by the Chinese patent drug KLP.

Implementing a preimplantation proteomic approach to advance assisted reproduction technologies in the framework of predictive, preventive, and personalized medicine

The evolution of the field of assisted reproduction technology (ART) in the last 40 years has significantly contributed to the management of global infertility. Despite the great numbers of live births that have been achieved through ART, there is still potential for increasing the success rates. As a result, there is a need to create optimum conditions in order to increase ART efficacy. The selection of the best sperm, oocyte, and embryo, as well as the achievement of optimal endometrial receptivity, through the contribution of new diagnostic and treatment methods, based on a personalized proteomic approach, may assist in the attainment of this goal. Proteomics represent a powerful new technological development, which seeks for protein biomarkers in human tissues. These biomarkers may aid to predict the outcome, prevent failure, and monitor in a personalized manner in vitro fertilization (IVF) cycles. In this review, we will present data from studies that have been conducted in the search for such biomarkers in order to identify proteins related to good sperm, oocyte, and embryo quality, as well as optimal endometrial receptivity, which may later lead to greater results and the desirable ART outcome.

Lipid Analysis of Follicular Fluids by UHPLC-ESI-HRMS Discovers Potential Biomarkers for Ovarian Hyperstimulation Syndrome

Ovarian hyperstimulation syndrome (OHSS) is a serious iatrogenic complication during ovarian stimulation. Even though the incidence of OHSS was relatively low in clinical practice, the consequence can be potentially devastating and life-threatening. Abnormal lipid metabolism may relate to the pathological development of OHSS, but there is still a research gap in the lipidomic research. So here in our study, an ultra-high-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UHPLC-ESI-HRMS) based lipidomic analysis was performed using follicular fluid samples obtained from 17 patients undergoing OHSS. The lipid profiles of OHSS patients were characterized by increased cholesterol ester (ChE) and decreased lysophosphatidylcholine (LPC), phosphatidylinositol (PI), sphingomyelin (SM), dimethylphosphatidylethanolamine (dMePE) and lysodimethylphosphatidylethanolamine (LdMePE). Totally 10 lipids including LPC(18:0), SM(d18:1/16:0), PC(18:0/18:1), PC(20:2/20:5), PC(16:0/18:1), TG(16:0/18:1/18:1), TG(16:0/18:2/18:2), TG(16:0/16:1/18:1), ChE(20:4) and TG(8:0/8:0/10:0) were selected as differential lipids. In conclusion, this study demonstrated the alteration of various lipids in OHSS patients, which suggested the key role of lipids during the development of OHSS and shed light on the further pathophysiological research of OHSS.

Whether Letrozole could reduce the incidence of early ovary hyperstimulation syndrome after assisted reproductive technology? A systematic review and meta-analysis

Background

Letrozole can significantly decrease the estrogen level, and has been administrated to prevent the incidence of early ovary hyperstimulation syndrome (OHSS). However, the effect of Letrozole on prevention of OHSS reached to controversial conclusions. The present meta-analysis aim to examine whether Letrozole could reduce the incidence of early OHSS after assisted reproductive technology (ART).

Methods

An exhaustive electronic literature search was conducted on MEDLINE, Google Scholar, CNKI and WANFANG MED ONLINE, from inception until May 2018. We include clinical trials that examined the effect of Letrozole on the prevention of early OHSS. The main outcome measures were the incidence of total early OHSS, mild early OHSS, moderate early OHSS, and severe early OHSS.

Results

Eight studies included in the review. Of these, five publications evaluated the effect of Letrozolel on the prevention of total, mild, moderate, and severe OHSS, respectively. The results indicated that there was a significantly decreased incidence of total OHSS with Letrozole compared with control group, and there were no significantly differences in the incidence of mild, moderate, and severe OHSS between study group with Letrozole and control group. Eight studies reported the incidence of moderate + severe OHSS. We found a significant decrease in incidence of moderate + severe OHSS in high-risk women with Letrozole.

Conclusions

Letrozole has no beneficial effect on the prevention of mild, moderate, and severe OHSS, individually; Letrozole should not be considered as the first-line treatment for prevention of OHSS. Further cohort studies are required to explore the effect of Letrozole on the prevention of OHSS.

Plain English Summary

This study aimed to examine whether Letrozole could reduce the incidence of early OHSS after assisted reproductive technology (ART). A meta-analysis including 8 studies was conducted. There were no significantly differences in the incidence of mild, moderate, and severe OHSS between study group with Letrozole and control group. Letrozole has no beneficial effect on the prevention of mild, moderate, and severe OHSS, individually.

Proteomic profile of follicular fluid from patients with polycystic ovary syndrome (PCOS) submitted to in vitro fertilization (IVF) compared to oocyte donors

OBJECTIVE

The follicular fluid (FF) of women with polycystic ovary syndrome (PCOS) seems to exhibit a profile different from that of fertile women, which may be related to folliculogenesis disruption in PCOS patients. The aim of this study was to evaluate the differentially expressed proteins in the FF of women with PCOS compared to oocyte donors (ODs).

METHODS

This screening study included thirteen (13) women who underwent in vitro fertilization (IVF) cycles: seven (7) ODs and six (6) PCOS patients. The patients underwent standard ovarian stimulation, and the FF was analysed using ion trap and time-of-flight liquid chromatography-mass spectrometry (LCMS-IT-TOF).

RESULTS

The FF of the patients was matched to 229 proteins, with 61 proteins exclusive to the PCOS group, 123 proteins exclusive to the ODs, and 45 proteins found in both groups. We highlight fetuin-A and vitamin D ligand protein, which were exclusively expressed in the PCOS group; Complement C3 overexpressed in the PCOS group; and 26S protease only expressed in the OD group. The canonical pathways LXR/RXR activation, FXR/RXR activation, prothrombin activation are directly related to the disrupted metabolism and increased inflammatory status found in PCOS patients.

CONCLUSIONS

The findings of the differentially expressed proteins and matched pathways are associated with folliculogenesis, indicating it relevance to oocyte quality.

Proteomic analysis of human follicular fluid in poor ovarian responders during in vitro fertilization

Poor ovarian response (POR) in controlled ovarian stimulation is often observed during in vitro fertilization and embryo transfer cycles and it is a major problem. A POR has been found to be related to several factors, including advanced age, high body mass index, and history of ovarian or pelvic surgery. However, it is difficult to predict POR, as there are no specific biomarkers known. In this study, we used quantitative proteomic analyses to investigate potential biomarkers that can predict poor response during in vitro fertilization based on follicular fluid samples. A total of 1079 proteins were identified using a high-resolution orbitrap mass spectrometer coupled online to a nanoflow-LC system. It is notable that 65 upregulated and 66 downregulated proteins were found to be functionally enriched in poor responders. We also validated these differentially expressed proteins using a triple-quadrupole mass spectrometer for quantification of targeted proteins. Of the differentially expressed proteins, three proteins (pregnancy zone protein, renin, and sushi repeat-containing protein SRPX) were regarded as statistically significant (p < 0.05).

Qualitative and Quantitative Analysis of Proteome and Peptidome of Human Follicular Fluid Using Multiple Samples from Single Donor with LC-MS and SWATH Methodology

Human follicular fluid (hFF) is a natural environment of oocyte maturation, and some components of hFF could be used to judge oocyte capability for fertilization and further development. In our pilot small-scale study three samples from four donors (12 samples in total) were analyzed to determine which hFF proteins/peptides could be used to differentiate individual oocytes and which are patient-specific. Ultrafiltration was used to fractionate hFF to high-molecular-weight (HMW) proteome (>10 kDa) and low-molecular-weight (LMW) peptidome (<10 kDa) fractions. HMW and LMW compositions were analyzed using LC-MS in SWATH data acquisition and processing methodology. In total we were able to identify 158 proteins, from which 59 were never reported before as hFF components. 55 (45 not reported before) proteins were found by analyzing LMW fraction, 67 (14 not reported before) were found by analyzing HMW fraction, and 36 were identified in both fractions of hFF. We were able to perform quantitative analysis for 72 proteins from HMW fraction of hFF. We found that concentrations of 11 proteins varied substantially among hFF samples from single donors, and those proteins are promising targets to identify biomarkers useful in oocyte quality assessment.

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.

The Use of Proteomics in Assisted Reproduction

Despite the explosive increase in the use of Assisted Reproductive Technologies (ART) over the last 30 years, their success rates remain suboptimal. Proteomics is a rapidly-evolving technology-driven science that has already been widely applied in the exploration of human reproduction and fertility, providing useful insights into its physiology and leading to the identification of numerous proteins that may be potential biomarkers and/or treatment targets of a successful ART pregnancy. Here we present a brief overview of the techniques used in proteomic analyses and attempt a comprehensive presentation of recent data from mass spectrometry-based proteomic studies in humans, regarding all components of ARTs, including the male and female gamete, the derived zygote and embryo, the endometrium and, finally, the ART offspring both pre- and postnatally.

Assessment of Blood Contamination in Biological Fluids Using MALDI-TOF MS

Biological fluid sample collection often includes the risk of blood contamination that may alter the proteomic profile of biological fluid. In proteomics studies, exclusion of contaminated samples is usually based on visual inspection and counting of red blood cells in the sample; analysis of specific blood derived proteins is less used. To fill the gap, we developed a fast and sensitive method for ascertainment of blood contamination in crude biological fluids, based on specific blood-derived protein, hemoglobin detection by MALDI-TOF MS. The MALDI-TOF MS based method allows detection of trace hemoglobin with the detection limit of 0.12 nM. UV-spectrometry, which was used as reference method, was found to be less sensitive. The main advantages of the presented method are that it is fast, effective, sensitive, requires very small sample amount and can be applied for detection of blood contamination in various biological fluids collected for proteomics studies. Method applicability was tested on human cerebrospinal and follicular fluid, which proteomes generally do not contain hemoglobin, however, which possess high risk for blood contamination. Present method successfully detected the blood contamination in 12 % of cerebrospinal fluid and 24 % of follicular fluid samples. High percentage of contaminated samples accentuates the need for initial inspection of proteomic samples to avoid incorrect results from blood proteome overlap.

Protein pathways working in human follicular fluid: the future for tailored IVF?

The human follicular fluid (HFF) contains molecules and proteins that may affect follicle growth, oocyte maturation and competence acquiring. Despite the numerous studies, an integrated broad overview on biomolecular and patho/physiological processes that are proved or supposed to take place in HFF during folliculogenesis and oocyte development is still missing. In this review we report, for the first time, all the proteins unambiguously detected in HFF and, applying DAVID (Database for Annotation, Visualization and Integrated Discovery) and MetaCore bioinformatic resources, we shed new lights on their functional correlation, delineating protein patterns and pathways with reasonable potentialities for oocyte quality estimation in in vitro fertilisation (IVF) programs. Performing a rigorous PubMed search, we redacted a list of 617 unique proteins unambiguously-annotated as HFF components. Their functional processing suggested the occurrence in HFF of a tight and highly dynamic functional-network, which is balanced by specific effectors, primarily involved in extracellular matrix degradation and remodelling, inflammation and coagulation. Metalloproteinases, thrombin and vitamin-D-receptor/retinoid-X-receptor-alpha resulted as the main key factors in the nets and their differential activity may be indicative of ovarian health and oocyte quality. Despite future accurate clinical investigations are absolutely needed, the present analysis may provide a starting point for more accurate oocyte quality estimation and for defining personalised therapies in reproductive medicine.

Proteomic analysis of human follicular fluid from fertile women

Background

Follicular fluid is a unique biological fluid in which the critical events of oocyte and follicular maturation and somatic cell-germ cell communication occur. Because of the intimate proximity of follicular fluid to the maturing oocyte, this fluid provides a unique window into the processes occurring during follicular maturation. A thorough identification of the specific components within follicular fluid may provide a better understanding of intrafollicular signaling, as well as reveal potential biomarkers of oocyte health for women undergoing assisted reproductive treatment. In this study, we used high and low pH HPLC peptide separations followed by mass spectrometry to perform a comprehensive proteomic analysis of human follicular fluid from healthy ovum donors. Next, using samples from a second set of patients, an isobaric mass tagging strategy for quantitative analysis was used to identify proteins with altered abundances after hCG treatment.

Results

A total of 742 follicular fluid proteins were identified in healthy ovum donors, including 413 that have not been previously reported. The proteins belong to diverse functional groups including insulin growth factor and insulin growth factor binding protein families, growth factor and related proteins, receptor signaling, defense/immunity, anti-apoptotic proteins, matrix metalloprotease related proteins, and complement activity. In a quantitative analysis, follicular fluid samples from age-matched women undergoing in vitro fertilization oocyte retrieval were compared and 17 follicular fluid proteins were found at significantly altered levels (p < 0.05) between pre-hCG and post-hCG samples. These proteins belong to a variety of functional processes, including protease inhibition, inflammation, and cell adhesion.

Conclusions

This database of FF proteins significantly extends the known protein components present during the peri-ovulatory period and provides a useful basis for future studies comparing follicular fluid proteomes in various fertility, disease, and environmental exposure conditions. We identified 17 differentially expressed proteins after hCG treatment and together these data showed the feasibility for defining biomarkers that illuminate how the ovarian follicle microenvironment is altered in various infertility-related conditions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12014-015-9077-6) contains supplementary material, which is available to authorized users.

Proteomics of follicular fluid from women with polycystic ovary syndrome suggests molecular defects in follicular development

CONTEXT

Polycystic ovary syndrome (PCOS), a major cause of anovulatory infertility, is characterized by arrested follicular growth. Altered protein levels in the follicular fluid surrounding the ovum may reflect the molecular defects of folliculogenesis in these women.

OBJECTIVE

To identify differentially regulated proteins in PCOS by comparing the follicular fluid protein repertoire of PCOS with healthy women.

METHODS

The follicular fluid samples were collected from PCOS and normo-ovulatory women undergoing in vitro fertilization. Follicular fluid proteins were subjected to digestion using trypsin, and resultant peptides were labeled with isobaric tags for relative and absolute quantification reagents and analyzed by liquid chromatography tandem mass spectrometry. Differential abundance of selected proteins was confirmed by ELISA.

RESULTS

A total of 770 proteins were identified, of which 186 showed differential abundance between controls and women with PCOS. Proteins involved in various processes of follicular development including amphiregulin; heparan sulfate proteoglycan 2; tumor necrosis factor, α-induced protein 6; plasminogen; and lymphatic vessel endothelial hyaluronan receptor 1 were found to be deregulated in PCOS. We also identified a number of new proteins from follicular fluid, whose function in the ovary is not yet clearly established. These include suprabasin; S100 calcium binding protein A7; and helicase with zinc finger 2, transcriptional coactivator.

CONCLUSIONS

Proteins indispensable for follicular growth were found to be differentially expressed in follicular fluid of women with PCOS, which may in part explain the aberrant folliculogenesis observed in these women.

Preliminary proteomic analysis on the alterations in follicular fluid proteins from women undergoing natural cycles or controlled ovarian hyperstimulation

PURPOSE

To study the differences in protein expression profiles of follicular fluid (FF) between controlled ovarian hyperstimulation (COH) and natural ovulatory cycles.

METHODS

Twelve infertile women undergoing in vitro fertilization and embryo transfer (IVF-ET), with matched clinical information, were retrospectively recruited in the IVF center of our university hospital, including six undergoing COH and another six with natural cycles. FF was sampled from dominant follicles with mature oocytes. Protein expression profiles in each FF sample were analyzed respectively using two-dimensional gel electrophoresis. Differentially expressed proteins were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and validated by western blotting. Differentially expressed proteins were further analyzed using Ingenuity Pathway Analysis (IPA) software.

RESULTS

Two proteins were downregulated and 11 proteins were upregulated (change ≥1.5-fold, P < 0.05) in the COH group. We identified one down-egulated and seven upregulated proteins using MALDI-TOF MS. Four differentially expressed proteins, including transferrin, complement component C3 (C3), haptoglobin and alpha-1-antitrypsin (AAT), were further validated by rate nephelometry and western blotting analyses. The IPA analysis revealed a significant network involved in the humoral immune and inflammatory responses.

CONCLUSIONS

The eight differentially expressed proteins were related to immune and inflammatory responses in the ovary. Our results provide new insights into the influence of COH on follicular (spp) development and IVF outcomes.

Oocyte environment: follicular fluid and cumulus cells are critical for oocyte health

Bidirectional somatic cell-oocyte signaling is essential to create a changing intrafollicular microenvironment that controls primordial follicle growth into a cohort of growing follicles, from which one antral follicle is selected to ovulate a healthy oocyte. Such intercellular communications allow the oocyte to determine its own fate by influencing the intrafollicular microenvironment, which in turn provides the necessary cellular functions for oocyte developmental competence, which is defined as the ability of the oocyte to complete meiosis and undergo fertilization, embryogenesis, and term development. These coordinated somatic cell-oocyte interactions attempt to balance cellular metabolism with energy requirements during folliculogenesis, including changing energy utilization during meiotic resumption. If these cellular mechanisms are perturbed by metabolic disease and/or maternal aging, molecular damage of the oocyte can alter macromolecules, induce mitochondrial mutations, and reduce adenosine triphosphate production, all of which can harm the oocyte. Recent technologies are now exploring transcriptional, translational, and post-translational events within the human follicle with the goal of identifying biomarkers that reliably predict oocyte quality in the clinical setting.

A proteomic analysis of human follicular fluid: comparison between younger and older women with normal FSH levels

The follicular fluid (FF) is produced during folliculogenesis and contains a variety of proteins that play important roles in follicle development and oocyte maturation. Age-related infertility is usually considered as a problem that can be solved by assisted reproduction technology. Therefore, the identification of novel biomarkers that are linked to reproductive aging is the subject of this study. FF was obtained from healthy younger (20–32 years old) and older (38–42 years old) women undergoing intracytoplasmic sperm injection (ICSI) due to male factor infertility. The FF was analyzed by two-dimensional gel electrophoresis (2-DE). The power of two-dimensional gel electrophoresis and the identification of proteins were exploited using matrix-assisted laser desorption-ionization time-of-flight/time-of-flight (MALDI-TOF-TOF) mass spectrometry. Twenty three protein spots showed reproducible and significant changes in the aged compared to the young group. Of these, 19 protein spots could be identified using MALDI-TOF-TOF-MS. As a result of MASCOT search, five unique downregulated proteins were identified in the older group. These were identified as serotransferrin, hemopexin precursor, complement C3, C4 and kininogen. A number of protein markers were found that may help develop diagnostic methods of infertility.

OMICS: Current and future perspectives in reproductive medicine and technology

Many couples present fertility problems at their reproductive age, and although in the last years, the efficiency of assisted reproduction techniques has increased, these are still far from being 100% effective. A key issue in this field is the proper assessment of germ cells, embryos and endometrium quality, in order to determine the actual likelihood to succeed. Currently available analysis is mainly based on morphological features of oocytes, sperm and embryos and although these strategies have improved the results, there is an urgent need of new diagnostic and therapeutic tools. The emergence of the - OMICS technologies (epigenomics, genomics, transcriptomics, proteomics and metabolomics) permitted the improvement on the knowledge in this field, by providing with a huge amount of information regarding the biological processes involved in reproductive success, thereby getting a broader view of complex biological systems with a relatively low cost and effort.

Proteomic analysis of human follicular fluid: a new perspective towards understanding folliculogenesis

Human follicular fluid is a complex body fluid that constitutes the microenvironment of developing follicles in the ovary. Follicular fluid contains a number of proteins that modulate oocyte maturation and ovulation. Information about the protein constituents of follicular fluid may provide a better understanding of ovarian physiology in addition to opening new avenues for investigating ovarian disorders. However, the composition of follicular fluid proteome remains poorly defined. In this study, we carried out SDS-PAGE, OFFGEL and SCX-based separation followed by LC-MS/MS analysis to characterize the proteome of human follicular fluid. We report high confidence identification of 480 proteins, of which 320 have not been described previously in the follicular fluid. The identified proteins belong to diverse functional categories including growth factor and hormones, receptor signaling, enzyme catalysis, defense/immunity and complement activity. Our dataset should serve as a resource for future studies aimed at developing biomarkers for monitoring oocyte and embryo quality, pregnancy outcomes and ovarian disorders.

BIOLOGICAL SIGNIFICANCE

Proteome analysis of human follicular fluid by multi-pronged approach of protein peptide fractionation revealed 480 proteins with high confidence. The identified protein may facilitate the understanding of folliculogenesis. This protein dataset should serve as a useful resource for development of biomarkers for oocyte quality, in vitro fertilization techniques and female infertility.