Comprehensive proteomic analysis of human endometrial fluid aspirate

Application of gel-based proteomic technique in female reproductive investigations

Recently, gel-based proteomics has been increasingly applied to investigate proteins involved in female reproductive tract in healthy and disease states. Gel-based proteomics coupled by mass spectrometry (MS) facilitate the identification of new proteins playing roles in cellular and molecular interactions underlying female reproductive biology and it is a useful method to identify novel biomarkers of diseases by studying thousands of proteins simultaneously involved in female reproductive tract in healthy state compared to disease state. This review will discuss the best studies areas contributed to female reproductive biology in which gel-based proteomics coupled by MS has been applied to generate proteome of female reproductive tract in a healthy state.

Cyclic decidualization of the human endometrium in reproductive health and failure

Decidualization denotes the transformation of endometrial stromal fibroblasts into specialized secretory decidual cells that provide a nutritive and immunoprivileged matrix essential for embryo implantation and placental development. In contrast to most mammals, decidualization of the human endometrium does not require embryo implantation. Instead, this process is driven by the postovulatory rise in progesterone levels and increasing local cAMP production. In response to falling progesterone levels, spontaneous decidualization causes menstrual shedding and cyclic regeneration of the endometrium. A growing body of evidence indicates that the shift from embryonic to maternal control of the decidual process represents a pivotal evolutionary adaptation to the challenge posed by invasive and chromosomally diverse human embryos. This concept is predicated on the ability of decidualizing stromal cells to respond to individual embryos in a manner that either promotes implantation and further development or facilitates early rejection. Furthermore, menstruation and cyclic regeneration involves stem cell recruitment and renders the endometrium intrinsically capable of adapting its decidual response to maximize reproductive success. Here we review the endocrine, paracrine, and autocrine cues that tightly govern this differentiation process. In response to activation of various signaling pathways and genome-wide chromatin remodeling, evolutionarily conserved transcriptional factors gain access to the decidua-specific regulatory circuitry. Once initiated, the decidual process is poised to transit through distinct phenotypic phases that underpin endometrial receptivity, embryo selection, and, ultimately, resolution of pregnancy. We discuss how disorders that subvert the programming, initiation, or progression of decidualization compromise reproductive health and predispose for pregnancy failure.

Annexin-A2 as predictor biomarker of recurrent disease in endometrial cancer

Endometrial carcinomas, the most common malignant tumour of the female genital tract, are usually diagnosed at an early stage with uterine-confined disease and an overall favourable prognosis. However, up to 20% of endometrial carcinomas will end up in recurrent disease, associated with a drop in survival and representing the major clinical challenge. Management of this group of risk patients relies on robust biomarkers that may predict which endometrial carcinomas will relapse. For this, we performed a proteomic analysis comparing primary lesions with recurrences and identified ANXA2 as a potential biomarker associated with recurrent disease that we further validated in an independent series of samples by immunohistochemistry. We demonstrated in vitro a role for ANXA2 in the promotion of metastasis rather than interfering with sensitivity to radio/chemotherapy. In addition, ANXA2 silencing resulted in a reduced metastatic pattern in a mice model of endometrial cancer dissemination, with a limited presence of circulating tumor cells. Finally, a retrospective study in a cohort of 93 patients showed that ANXA2 effectively predicted those endometrioid endometrial carcinomas that finally recurred. Importantly, ANXA2 demonstrated a predictive value also among low risk Stage I endometrioid endometrial carcinomas, highlighting the clinical utility of ANXA2 biomarker as predictor of recurrent disease in endometrial cancer. Retrospective and prospective studies are ongoing to validate ANXA2 as a potential tool for optimal stratification of patients susceptible to receive radical surgery and radio/chemotherapy.

World Endometriosis Research Foundation Endometriosis Phenome and Biobanking Harmonization Project: III. Fluid biospecimen collection, processing, and storage in endometriosis research

Objective

To harmonize standard operating procedures (SOPs) and standardize the recording of associated data for collection, processing, and storage of fluid biospecimens relevant to endometriosis.

Design

An international collaboration involving 34 clinical/academic centers and 3 industry collaborators from 16 countries on 5 continents.

Setting

In 2013, 2 workshops were conducted, followed by global consultation, bringing together 54 leaders in endometriosis research and sample processing worldwide.

Patient(s)

None.

Intervention(s)

Consensus SOPs were based on: [1] systematic comparison of SOPs from 18 global centers collecting fluid samples from women with and without endometriosis on a medium/large scale (publication on >100 cases), [2] literature evidence where available, or consultation with laboratory experts otherwise, and [3] several global consultation rounds.

Main Outcome Measure(s)

Standard recommended and minimum required SOPs for biofluid collection, processing, and storage in endometriosis research.

Result(s)

We developed recommended standard and minimum required SOPs for the collection, processing, and storage of plasma, serum, saliva, urine, endometrial/peritoneal fluid, and menstrual effluent, and a biospecimen data-collection form necessary for interpretation of sample-derived results.

Conclusion(s)

The Endometriosis Phenome and Biobanking Harmonisation Project SOPs allow endometriosis research centers to decrease variability in biofluid sample results, facilitating between-center comparisons and collaborations. The procedures are also relevant to research into other female conditions involving biofluid samples subject to cyclic reproductive influences. The consensus SOPs are based on the best available evidence; areas with limited evidence are identified as requiring further pilot studies. The SOPs will be reviewed based on investigator feedback, and through systematic tri-annual follow-up. Updated versions will be made available at: endometriosisfoundation.org/ephect.

Regulation of mucosal immunity in the female reproductive tract: the role of sex hormones in immune protection against sexually transmitted pathogens

The immune system in the female reproductive tract (FRT) does not mount an attack against human immunodeficiency virus (HIV) or other sexually transmitted infections (STI) with a single endogenously produced microbicide or with a single arm of the immune system. Instead, the body deploys dozens of innate antimicrobials to the secretions of the FRT. Working together, these antimicrobials along with mucosal antibodies attack viral, bacterial, and fungal targets. Within the FRT, the unique challenges of protection against sexually transmitted pathogens coupled with the need to sustain the development of an allogeneic fetus, has evolved in such a way that sex hormones precisely regulate immune function to accomplish both tasks. The studies presented in this review demonstrate that estradiol (E2 ) and progesterone secreted during the menstrual cycle act both directly and indirectly on epithelial cells, fibroblasts and immune cells in the reproductive tract to modify immune function in a way that is unique to specific sites throughout the FRT. As presented in this review, studies from our laboratory and others demonstrate that the innate and adaptive immune systems are under hormonal control, that protection varies with the stage of the menstrual cycle and as such, is dampened during the secretory stage of the cycle to optimize conditions for fertilization and pregnancy. In doing so, a window of STI vulnerability is created during which potential pathogens including HIV enter the reproductive tract to infect host targets.

Recent advances in understanding endometrial receptivity: molecular basis and clinical applications

Advancement in the field of ART has lead to the possibility of achieving good quality embryos. However, the success rate in ART needs further improvement. This is largely dependent on identifying the receptive endometrium for the successful implantation of embryos as well as modulating the endometrium to the receptive stage. In the last half-a-decade, focus has been shifting toward identifying the receptive endometrium. Here, we summarize different tools explored to identify receptive endometrium from the literature, mainly focusing on the past decade, with the help of PubMed. The quest to identify endometrial receptivity markers has lead to the exploration of morphological features at micro and macro scale levels. A large number of studies at molecular levels have focused on genomic, proteomic and lipidomic targets. Recent development of endometrial receptivity array is a promising diagnostic instrument. However, a noninvasive possibility for the diagnosis of endometrial receptivity would be an ideal tool, which could be used in the clinic to improve the success rate of ART. Improved knowledge on endometrial receptivity will not only help to improve the diagnosis and treatment of infertility but will also give possibilities to develop new contraceptive methods targeting the endometrium.

Embryo implantation: biology, evaluation, and enhancement

PURPOSE OF REVIEW

Implantation is an essential step in the development of a pregnancy, but often fails in humans. In assisted reproductive technologies, implantation failure continues to impair treatment outcomes, with distressing results for patients and physicians.

RECENT FINDINGS

Morphokinetics, comprehensive chromosome screening, and the analysis of embryo-derived products detectable in spent culture media offer new means of assessing embryo viability. However, all await validation in randomized controlled trials. Genomic, transcriptomic, and secretomic technologies are similarly being exploited to define specific biomarkers of endometrial receptivity with the aim of identifying novel therapeutic interventions. However, to date no single, clinically relevant molecular marker capable of indicating endometrial receptivity has been reported. Recent work continues to describe the key signalling pathways which result in acceptance or rejection of the implanting embryo. In-vitro studies have revealed that the decidualized endometrium plays an important role in natural embryo selection, which could change our understanding of the aetiology and treatment of reproductive failure.

SUMMARY

Recent developments in analytical techniques have initiated a search for biomarkers of embryo quality and endometrial receptivity, and in-vitro studies have revealed novel roles for the decidualized endometrium as a biosensor of embryo quality.

Guidelines for the design, analysis and interpretation of 'omics' data: focus on human endometrium

BACKGROUND

'Omics' high-throughput analyses, including genomics, epigenomics, transcriptomics, proteomics and metabolomics, are widely applied in human endometrial studies. Analysis of endometrial transcriptome patterns in physiological and pathophysiological conditions has been to date the most commonly applied 'omics' technique in human endometrium. As the technologies improve, proteomics holds the next big promise for this field. The 'omics' technologies have undoubtedly advanced our knowledge of human endometrium in relation to fertility and different diseases. Nevertheless, the challenges arising from the vast amount of data generated and the broad variation of 'omics' profiling according to different environments and stimuli make it difficult to assess the validity, reproducibility and interpretation of such 'omics' data. With the expansion of 'omics' analyses in the study of the endometrium, there is a growing need to develop guidelines for the design of studies, and the analysis and interpretation of 'omics' data.

METHODS

Systematic review of the literature in PubMed, and references from relevant articles were investigated up to March 2013.

RESULTS

The current review aims to provide guidelines for future 'omics' studies on human endometrium, together with a summary of the status and trends, promise and shortcomings in the high-throughput technologies. In addition, the approaches presented here can be adapted to other areas of high-throughput 'omics' studies.

CONCLUSION

A highly rigorous approach to future studies, based on the guidelines provided here, is a prerequisite for obtaining data on biological systems which can be shared among researchers worldwide and will ultimately be of clinical benefit.

In-vitro model systems for the study of human embryo-endometrium interactions

Implantation requires highly orchestrated interactions between the developing embryo and maternal endometrium. The association between abnormal implantation and reproductive failure is evident, both in normal pregnancy and in assisted reproduction patients. Failure of implantation is the pregnancy rate-limiting step in assisted reproduction, but, as yet, empirical interventions have largely failed to address this problem. Better understanding of the mechanisms underlying human embryo-endometrium signalling is a prerequisite for the further improvement of assisted reproduction outcomes and the development of effective interventions to prevent early pregnancy loss. Studying human embryo implantation is challenging since in-vivo experiments are impractical and unethical, and studies in animal models do not always translate well to humans. However, in recent years in-vitro models have been shown to provide a promising way forward. This review discusses the principal models used to study early human embryo development and initial stages of implantation in vitro. While each model has limitations, exploiting these models will improve understanding of the molecular mechanisms and embryo-endometrium cross-talk at the early implantation site. They provide valuable tools to study early embryo development and pathophysiology of reproductive disorders and have revealed novel disease mechanisms such as the role of epigenetic modifications in recurrent miscarriage.

Uterine secretome and its modulation in rat (Rattus norvegicus)

The present study identifies uterine fluid (UF) proteins that display differential abundance during the embryo-permissive phase in nonconception and conception cycles in rats. UF samples were collected from nonpregnant rats in the proestrous (n=17) and metestrous (n=18) phases and also from pregnant (n=17) and pseudopregnant (n=17) rats on day 4 post coitus. UF protein profile in the metestrous phase was compared with that in the proestrous phase. Similarly, UF protein profile of the pregnant rats was compared with that of the pseudopregnant rats. Two-dimensional PAGE, followed by densitometric analysis of the paired protein spots, revealed differential abundance of 44 proteins in the metestrous phase, compared with that in the proestrous phase. Of these, 29 proteins were identified by matrix-assisted laser desorption/ionization time-of-flight or liquid chromatography–tandem mass spectrometry. Functional groups such as proteases, protease inhibitors, and oxidoreductases were enriched in differentially abundant proteins. Total protease activity in UF was found to be significantly (P<0.05; t-test) higher in the proestrous phase, compared with that in the metestrous phase. Furthermore, 41 UF proteins were found to be differentially abundant in pregnant rats, compared with pseudopregnant rats. Of these, 11 proteins could be identified. Immunoblotting analysis confirmed significantly higher (P<0.05; t-test) abundance of β-actin, Rho-specific guanine nucleotide dissociation inhibitor alpha (Rho-GDIα), and peroxiredoxin-2 and -6 in the metestrous phase, compared with that in the proestrous phase. Compared with pseudopregnant rats, pregnant rats had significantly higher (P<0.05; t-test) levels of UF β-actin and Rho-GDIα. Furthermore, these proteins could be detected in the culture supernatants of endometrial epithelial cell lines, thereby providing an evidence of their secretion from endometrial epithelial cells. Data obtained from the study expand our knowledge on the uterine milieu that favours embryo implantation.

Assessing receptivity in the endometrium: the need for a rapid, non-invasive test

Successful implantation of an embryo into the uterus requires synchrony between the blastocyst and the endometrium. Endometrial preparedness, or receptivity, occurs only for a very short time during the mid-secretory phase of the menstrual cycle in fertile women. Failure to achieve receptivity results in infertility and is a rate-limiting step for IVF success. Frozen embryo transfer in non-stimulation cycles is already improving live birth rates. However, an important tool that is missing in the armoury of reproductive specialists is a means to rapidly assess endometrial receptivity, either during initial assessment or immediately prior to embryo transfer. The development of a wealth of omics technologies now opens the way for identifying potential receptivity markers, although validation of these is still a major issue. This review assesses the current state of the field and the requirements to proceed to a valid clinical test.

High-throughput proteomic characterization of plasma rich in growth factors (PRGF-Endoret)-derived fibrin clot interactome

Plasma rich in growth factors (PRGF®-Endoret®) is an autologous technology that contains a set of proteins specifically addressed to wound healing and tissue regeneration. The scaffold formed by using this technology is a clot mainly composed of fibrin protein, forming a three-dimensional (3D) macroscopic network. This biomaterial is easily obtained by biotechnological means from blood and can be used in a range of situations to help wound healing and tissue regeneration. Although the main constituent of this clot is the fibrin scaffold, little is known about other proteins interacting in this clot that may act as adjuvants in the healing process. The aim of this study was to characterize the proteins enclosed by PRGF-Endoret scaffold, using a double-proteomic approach that combines 1D-SDS-PAGE approach followed by LC-MS/MS, and 2-DE followed by MALDI-TOF/TOF. The results presented here provide a description of the catalogue of key proteins in close contact with the fibrin scaffold. The obtained lists of proteins were grouped into families and networks according to gene ontology. Taken together, an enrichment of both proteins and protein families specifically involved in tissue regeneration and wound healing has been found.

Proteomics in reproductive biology: beacon for unraveling the molecular complexities

Proteomics, an interface of rapidly evolving advances in physics and biology, is rapidly developing and expanding its potential applications to molecular and cellular biology. Application of proteomics tools has contributed towards identification of relevant protein biomarkers that can potentially change the strategies for early diagnosis and treatment of several diseases. The emergence of powerful mass spectrometry-based proteomics technique has added a new dimension to the field of medical research in liver, heart diseases and certain forms of cancer. Most proteomics tools are also being used to study physiological and pathological events related to reproductive biology. There have been attempts to generate the proteomes of testes, sperm, seminal fluid, epididymis, oocyte, and endometrium from reproductive disease patients. Here, we have reviewed proteomics based investigations in humans over the last decade, which focus on delineating the mechanism underlying various reproductive events such as spermatogenesis, oogenesis, endometriosis, polycystic ovary syndrome, embryo development. The challenge is to harness new technologies like 2-DE, DIGE, MALDI-MS, SELDI-MS, MUDPIT, LC-MS etc., to a greater extent to develop widely applicable clinical tools in understanding molecular aspects of reproduction both in health and disease.

Proteomic analysis of menstrual blood

Menstruation is the expulsion of the endometrial lining of the uterus following a nearly month long preparation for embryo implantation and pregnancy. Increasingly, the health of the endometrium is being recognized as a critical factor in female fertility, and proteomes and transcriptomes from endometrial biopsies at different stages of the menstrual cycle have been studied for both diagnostic and therapeutic purposes (1 Kao, L. C., et al. 2003 Endocrinology 144, 2870-2881; Strowitzki, Tet al. 2006 Hum. Reprod. Update 12, 617-630; DeSouza, L., et al. 2005 Proteomics 5, 270-281). Disorders of the uterus ranging from benign to malignant tumors, as well as endometriosis, can cause abnormal menstrual bleeding and are frequently diagnosed through endometrial biopsy (Strowitzki, Tet al. 2006 Hum. Reprod. Update 12, 617-630; Ferenczy, A. 2003 Maturitas 45, 1-14). Yet the proteome of menstrual blood, an easily available noninvasive source of endometrial tissue, has yet to be examined for possible causes or diagnoses of infertility or endometrial pathology. This study employed five different methods to define the menstrual blood proteome. A total of 1061 proteins were identified, 361 were found by at least two methods and 678 were identified by at least two peptides. When the menstrual blood proteome was compared with those of circulating blood (1774 proteins) and vaginal fluid (823 proteins), 385 proteins were found unique to menstrual blood. Gene ontology analysis and evaluation of these specific menstrual blood proteins identified pathways consistent with the processes of the normal endometrial cycle. Several of the proteins unique to menstrual blood suggest that extramedullary uterine hematopoiesis or parenchymal hemoglobin synthesis may be occurring in late endometrial tissue. The establishment of a normal menstrual blood proteome is necessary for the evaluation of its usefulness as a diagnostic tool for infertility and uterine pathologies. Identification of unique menstrual blood proteins should aid the forensic community in distinguishing menstrual blood from circulating blood.

Conceptus-endometrium crosstalk during maternal recognition of pregnancy in cattle

Successful growth and development of the posthatching blastocyst and pregnancy establishment are a result of the interaction between a competent embryo and a receptive uterine environment. We examined the global transcriptome profiles of the Day 16 bovine conceptus and pregnant endometrium tissues using RNA-Seq to identify genes that contribute to the dialogue during the period of pregnancy recognition. Using stringent filtering criterion, a total of 16 018 and 16 262 transcripts of conceptus and pregnant endometrium origin, respectively, were identified with distinct tissue-specific expression profiles. Of these, 2261 and 2505 transcripts were conceptus and endometrium specific. Using Cytoscape software, a total of 133 conceptus ligands that interact with corresponding receptors on the endometrium and 121 endometrium ligands that interact with corresponding receptors on the conceptus were identified. While 87 ligands were commonly detected, 46 were conceptus specific and 34 endometrium specific. This study is one of the first to provide a comprehensive list of potentially secreted molecules in the conceptus that interact with receptors on the endometrium and vice versa during the critical window of maternal recognition of pregnancy. The identified tissue-specific genes may serve as candidates to study pregnancy recognition and they or downstream products may represent potential early markers of pregnancy.

Uterine lavage or aspirate: which view of the intrauterine environment?

Fluid within the uterine cavity provides the microenvironment for preimplantation blastocyst development and early implantation. Analysis of uterine fluid sampled by aspiration or lavage provides a view of this microenvironment but the similarity or otherwise of the sample components is not known. This study compared proteins in aspirates versus lavage samples taken sequentially from the same women, using surface-enhanced laser desorption/ionization-time of flight-mass spectrometry (SELDI-TOF-MS), multiplex cytokine assays, and an activity assay for proprotein convertase 6. Both lavage and aspiration enabled analysis of uterine fluid components, but they provided substantially different protein profiles. Although there were many similarities in overall protein profiles and most specific proteins examined were detected in both fluids, these were neither qualitatively nor quantitatively comparable within each participant. A likely explanation is that lavage samples the entire uterine cavity including washing the endometrial surface (glycocalyx), whereas aspiration sampling is very local.

Impact of genomic stability on protein expression in endometrioid endometrial cancer

Background:

Genomic stability is one of the crucial prognostic factors for patients with endometrioid endometrial cancer (EEC). The impact of genomic stability on the tumour tissue proteome of EEC is not yet well established.

Methods:

Tissue lysates of EEC, squamous cervical cancer (SCC), normal endometrium and squamous cervical epithelium were subjected to two-dimensional (2D) gel electrophoresis and identification of proteins by MALDI TOF MS. Expression of selected proteins was analysed in independent samples by immunohistochemistry.

Results:

Diploid and aneuploid genomically unstable EEC displayed similar patterns of protein expression. This was in contrast to diploid stable EEC, which displayed a protein expression profile similar to normal endometrium. Approximately 10% of the differentially expressed proteins in EEC were specific for this type of cancer with differential expression of other proteins observed in other types of malignancy (e.g., SCC). Selected proteins differentially expressed in 2D gels of EEC were further analysed in an EEC precursor lesion, that is, atypical hyperplasia of endometrium, and showed increased expression of CLIC1, EIF4A1 and PRDX6 and decreased expression of ENO1, ANXA4, EMD and Ku70.

Conclusion:

Protein expression in diploid and aneuploid genomically unstable EEC is different from the expression profile of proteins in diploid genomically stable EEC. We showed that changes in expression of proteins typical for EEC could already be detected in precursor lesions, that is, atypical hyperplasia of endometrium, highlighting their clinical potential for improving early diagnostics of EEC.

Uromodulin and α(1)-antitrypsin urinary peptide analysis to differentiate glomerular kidney diseases

BACKGROUND/AIMS

Glomerular kidney disease (GKD) is suspected in patients based on proteinuria, but its diagnosis relies primarily on renal biopsy. We used urine peptide profiling as a noninvasive means to link GKD-associated changes to each glomerular entity.

METHODS

Urinary peptide profiles of 60 biopsy-proven glomerular patients and 14 controls were analyzed by combining magnetic bead peptide enrichment, MALDI-TOF MS analysis, and ClinProTools v2.0 to select differential peptides. Tentative identification of the differential peptides was carried out by HPLC-MS/MS.

RESULTS

The HPLC-MS/MS results suggest that uromodulin (UMOD; m/z: 1682, 1898 and 1913) and α(1)-antitrypsin (A1AT; m/z: 1945, 2392 and 2505) are differentially expressed urinary peptides that distinguish between GKD patients and healthy subjects. Low UMOD and high A1AT peptide abundance was observed in 80-92% of patients with GKD. Proliferative forms of GKD were distinguished from nonproliferative forms, based on a combination of UMOD and A1AT peptides. Nonproliferative forms correlated with higher A1AT peptide levels - focal segmental glomerulosclerosis was linked more closely to high levels of the m/z 1945 peptide than minimal change disease.

CONCLUSION

We describe a workflow - urinary peptide profiling coupled with histological findings - that can be used to distinguish GKD accurately and noninvasively, particularly its nonproliferative forms.

Human urine proteomics: building a list of human urine cancer biomarkers

In the last decade, several reports have focused on the identification and characterization of proteins present in urine. In an effort to build a list of proteins of interest as biomarkers, we reviewed the largest urine proteomes and built two updated lists of proteins of interest (available as supplementary tables). The first table includes a consensus list of 443 proteins found in urine by independent laboratories and reported on the top three largest urine proteomes currently published. This consensus list of proteins could serve as biomarkers to diagnose, monitor and manage a number of diseases. Here, we focus on a reduced list of 35 proteins with potential interest as cancer biomarkers in urine following two criteria: first, proteins previously detected in urine using bottom-up proteomic experiments, and second, those suggested as cancer protein biomarkers in human plasma. In an effort to standardize the information presented and its use in future studies, here we include the updated International Protein Index (v. 3.80) and primary Swiss-Prot accession numbers, official gene symbols and recommended full names. The main variables that influence urine proteomic experiments are also discussed.

PC6 levels in uterine lavage are closely associated with uterine receptivity and significantly lower in a subgroup of women with unexplained infertility

BACKGROUND Embryo implantation requires a healthy embryo and a receptive uterus. Uterine incompetence contributes significantly to implantation failure and infertility. To date, there are no reliable biochemical methods that can determine whether the uterus is receptive. Proprotein convertase 5/6 (PC6) is tightly regulated in the uterus and critical for receptivity and implantation; its secretory nature predicts PC6 to be secreted into the uterine cavity. The present study examines whether PC6 is detectable in uterine lavage and whether there is any correlation between secreted PC6 levels and uterine receptivity. METHODS Western blotting determined the presence of PC6 protein in uterine lavage. A sensitive and high-throughput activity assay was established and validated. This assay was applied to 103 lavages collected from different phases of the menstrual cycle from women with proven fertility or unexplained infertility. RESULTS Uterine lavage contained PC6 protein with levels paralleling enzymatic activity. PC6 levels were significantly higher in the receptive than in the non-receptive phase in fertile women, and the putative receptive phase levels in a subgroup of women with unexplained infertility were significantly lower than in the fertile counterparts. CONCLUSIONS PC6 levels in uterine lavage are significantly elevated in the luteal phase of fertile women and markedly reduced in a subgroup of women with unexplained infertility. Uterine fluid is a valuable source of material to evaluate uterine function. Detection of PC6 in uterine fluid may lead to the development of a rapid and relatively non-surgical assessment of uterine receptivity.

Urinary peptide profiling identifies a panel of putative biomarkers for diagnosing and staging endometriosis

OBJECTIVE

To identify a potential diagnostic endometriosis marker using matrix-enhanced laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS)-based urinary proteomics.

DESIGN

Prospective randomized pilot study.

SETTING

University hospital, tertiary referral center for endometriosis.

PATIENT(S)

53 women undergoing laparoscopic surgery for pain and/or infertility comprising 30 women without endometriosis and 23 with endometriosis.

INTERVENTION(S)

Laparoscopy and urine specimens.

MAIN OUTCOME MEASURE(S)

Urinary peptide profiles.

RESULT(S)

We observed distinct patterns of peptide profiles in the urine samples of women presenting with typical clinical symptoms of endometriosis. Six statistically significant putative peptide markers were identified (four during the periovulatory phase and two during the luteal phase) by comparing controls with moderate/severe endometriosis patients. The periovulatory peptide mass of 1,767.1 Da and the luteal peptide mass of 1,824.3 Da both showed a sensitivity of 75% and a specificity of 85% and 71%, respectively. Also detected were seven peptide markers (two during the periovulatory phase and five during the luteal phase) by comparing the urinary peptide profiles of patients with minimal/mild to moderate/severe endometriosis. The periovulatory peptide mass of 3,280.9 Da and the luteal peptide mass of 1,933.8 Da showed a sensitivity of 82% and 75% and a specificity of 88% and 75%, respectively.

CONCLUSION(S)

Urinary proteomic analysis may provide a novel method of diagnosing and staging endometriosis.

Proteomic profile of uterine luminal fluid from early pregnant ewes

Embryonic development is a time-sensitive period that requires a synchronized uterine environment, which is created by the secretion of proteins from both the embryo and uterus. Numerous studies have identified uterine luminal proteins and related these to specific adaptations during early pregnancy (EP). However, no study has yet utilized LC-MS/MS to identify the signature profile of proteins in the uterine lumen during EP. In this study, uterine luminal fluid from nonpregnant (NP; n = 3) and EP (n = 3; gestational day 16) ewes were analyzed by LC-MS/MS and validated by Western immunoblotting. We identified a unique signature profile for EP luminal fluid; 15 proteins related to specific aspects of embryonic development including growth and remodeling, immune system regulation, oxidative stress balance, and nutrition were significantly altered (up to 65-fold of NP) in EP profile. Specific uterine remodeling proteins such as transgelin (P = 0.008) and placental proteins like PP9 (P = 0.02) were present in EP luminal fluid but were barely detectable in the NP flushings. Direct correlations (R(2) = 0.84, P = 0.01) were observed between proteomics and immunoblotting. These data provide information on dynamic physiological processes associated with EP at the level of the uterus and conceptus and may potentially demonstrate a signature profile associated with embryonic well-being.

Evaluation of endometrial biomarkers for semi-invasive diagnosis of endometriosis

OBJECTIVE

To test the hypothesis that specific proteins and peptides are expressed differentially in eutopic endometrium of women with and without endometriosis and at specific stages of the disease (minimal, mild, moderate, or severe) during the secretory phase.

DESIGN

Patients with endometriosis were compared with controls.

SETTING

University hospital.

PATIENT(S)

A total of 29 patients during the secretory phase were selected for this study on the basis of cycle phase and presence or absence of endometriosis.

INTERVENTION(S)

Endometriosis was confirmed laparoscopically and histologically in 19 patients with endometriosis of revised American Society for Reproductive Medicine stages (9 minimal-mild and 10 moderate-severe), and the presence of a normal pelvis was documented by laparoscopy in 10 controls.

MAIN OUTCOME MEASURE(S)

Protein expression of endometrium was evaluated with use of surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. The differential expression of protein mass peaks was analyzed with use of support vector machine algorithms and logistic regression models.

RESULT(S)

Data preprocessing resulted in differential expression of 73, 30, and 131 mass peaks between controls and patients with endometriosis (all stages), with minimal-mild endometriosis, and with moderate-severe endometriosis, respectively. Endometriosis was diagnosed with high sensitivity (89.5%) and specificity (90%) with use of five down-regulated mass peaks (1.949 kDa, 5.183 kDa, 8.650 kDa, 8.659 kDa, and 13.910 kDa) obtained after support vector machine ranking and logistic regression classification. With use of a similar analysis, minimal-mild endometriosis was diagnosed with four mass peaks (two up-regulated: 35.956 kDa and 90.675 kDa and two down-regulated: 1.924 kDa and 2.504 kDa) with maximal sensitivity (100%) and specificity (100%). The 90.675-kDa and 35.956-kDa mass peaks were identified as T-plastin and annexin V, respectively.

CONCLUSION(S)

Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry analysis of secretory phase endometrium combined with bioinformatics puts forward a prospective panel of potential biomarkers with sensitivity of 100% and specificity of 100% for the diagnosis of minimal to mild endometriosis.

Proteomics and the search for biomarkers of female reproductive diseases

Over the past decade, high-throughput proteomics technologies have evolved considerably and have become increasingly more commonly applied to the investigation of female reproductive diseases. Proteomic approaches facilitate the identification of new disease biomarkers by comparing the abundance of hundreds of proteins simultaneously to find those specific to a particular clinical condition. Some of the best studied areas of female reproductive biology applying proteomics include gynaecological cancers, endometriosis and endometrial infertility. This review will discuss the progress that has been made in these areas and will highlight some of the emerging technologies that promise to contribute to better understanding of the female reproductive disease.

iTRAQ-based quantitative analysis of protein mixtures with large fold change and dynamic range

Quantitation of changes in protein abundance is key to understanding the alterations that biological systems undergo and to discovering novel biomarkers. Currently, HPLC-MS/MS can be used to quantify changes in protein expression levels [Ong, S. E. and Mann, M., Nat. Chem. Biol. 2005, 1, 252-262]. Nevertheless, quantitative analysis of protein mixtures by HPLC-MS/MS is still hampered by the wide range of protein expression levels, the high dynamic range of protein concentrations and the lack of reliable quantitation algorithms [D'Ascenzo, M., et al. Brief. Funct. Genomic. Proteomic. 2008, 7, 127-135; Lin, W. T., et al., J. Proteome Res. 2006, 5, 2328-2338; Matthiesen, R., et al. J. Proteome Res. 2005, 4, 2338-2347; Yu, C. Y., et al. Nucleic Acids Res. 2007, 35, W707-W712]. In this context, we describe two different samples (4-protmix and 8-protmix) suitable for relative protein quantitation using iTRAQ. Using the 4-protmix, relative protein changes of up to 24-fold were measured. The 8-protmix allowed the quantitation of the relative protein changes in a mixture of proteins within the range of two orders of magnitude in concentration and ten-fold differences in relative abundance. We propose that the two samples are suited to test the iTRAQ quantitative proteomic workflow. We analyzed the iTRAQ samples with a LTQ Orbitrap using "higher energy collision-induced dissociation" fragmentation [Olsen, J. V., et al., Nat. Methods 2007, 4, 709-712] and quantified with Proteome Discoverer v.1.1 (Thermo Fisher Scientific). We believe that the presented protein mixtures will be useful to assess the performance of the iTRAQ-based quantitation proteomic strategy in any laboratory.