Age-related variations in follicular apolipoproteins may influence human oocyte maturation and fertility potential

Proteomics profiling reveals lipid metabolism abnormalities during oogenesis in unexplained recurrent pregnancy loss

Background

Unexplained recurrent pregnancy loss (URPL) is a clinical dilemma in reproductive fields. Its diagnosis is mainly exclusionary after extensive clinical examination, and some of the patients may still face the risk of miscarriage.

Methods

We analyzed follicular fluid (FF) from in vitro fertilization (IVF) in eight patients with URPL without endocrine abnormalities or verifiable causes of abortion and eight secondary infertility controls with no history of pregnancy loss who had experienced at least one normal pregnancy and delivery by direct data-independent acquisition (dDIA) quantitative proteomics to identify differentially expressed proteins (DEPs). In this study, bioinformatics analysis was performed using online software including g:profiler, String, and ToppGene. Cytoscape was used to construct the protein-protein interaction (PPI) network, and ELISA was used for validation.

Results

Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the DEPs are involved in the biological processes (BP) of complement and coagulation cascades. Apolipoproteins (APOs) are key proteins in the PPI network. ELISA confirmed that APOB was low-expressed in both the FF and peripheral blood of URPL patients.

Conclusion

Dysregulation of the immune network intersecting coagulation and inflammatory response is an essential feature of URPL, and this disequilibrium exists as early as the oogenesis stage. Therefore, earlier intervention is necessary to prevent the development of URPL. Moreover, aberrant lipoprotein regulation appears to be a key factor contributing to URPL. The mechanism by which these factors are involved in the complement and coagulation cascade pathways remains to be further investigated, which also provides new candidate targets for URPL treatment.

Follicular Fluid Proteomic Analysis of Women Undergoing Assisted Reproduction Suggests That Apolipoprotein A1 Is a Potential Fertility Marker

Infertility affects millions worldwide, posing a significant global health challenge. The proteomic analysis of follicular fluid provides a comprehensive view of the complex molecular landscape within ovarian follicles, offering valuable information on the factors influencing oocyte development and on the overall reproductive health. The follicular fluid is derived from the plasma and contains various proteins that can have different roles in oocyte health and infertility, and this fluid is a critical microenvironment for the developing oocytes as well. Using the high-performance liquid chromatography-mass spectrometry method, we investigated the protein composition of the follicular fluid, and after classification, we carried out relative quantification of the identified proteins in the pregnant (P) and non-pregnant (NP) groups. Based on the protein-protein interaction analysis, albumin and apolipoprotein A1 (ApoA1) were found to be hub proteins, and the quantitative comparison of the P and NP groups resulted in a significantly lower concentration of ApoA1 and high-density lipoprotein cholesterol in the P group. As both molecules are involved in the cholesterol transport, we also investigated their role in the development of oocytes and in the prediction of fertility.

Advanced maternal age leads to changes within the insulin/IGF system and lipid metabolism in the reproductive tract and preimplantation embryo: insights from the rabbit model

Reproductive potential in women declines with age. The impact of ageing on embryo-maternal interactions is still unclear. Rabbits were used as a reproductive model to investigate maternal age-related alterations in reproductive organs and embryos on Day 6 of pregnancy. Blood, ovaries, endometrium, and blastocysts from young (16-20 weeks) and advanced maternal age phase (>108 weeks, old) rabbits were analysed at the mRNA and protein levels to investigate the insulin-like growth factor (IGF) system, lipid metabolism, and stress defence system. Older rabbits had lower numbers of embryos at Day 6 of pregnancy. Plasma insulin and IGF levels were reduced, which was accompanied by paracrine regulation of IGFs and their receptors in ovaries and endometrium. Embryos adapted to hormonal changes as indicated by reduced embryonic IGF1 and 2 levels. Aged reproductive organs increased energy generation from the degradation of fatty acids, leading to higher oxidative stress. Stress markers, including catalase, superoxide dismutase 2, and receptor for advanced glycation end products were elevated in ovaries and endometrium from aged rabbits. Embryonic fatty acid uptake and β-oxidation were increased in both embryonic compartments (embryoblast and trophoblast) in old rabbits, associated with minor changes in the oxidative and glycative stress defence systems. In summary, the insulin/IGF system, lipid metabolism, and stress defence were dysregulated in reproductive tissues of older rabbits, which is consistent with changes in embryonic metabolism and stress defence. These data highlight the crucial influence of maternal age on uterine adaptability and embryo development.

Integration analysis of metabolome and transcriptome reveals the effect of exogenous supplementation with mixtures of vitamins ADE, zinc, and selenium on follicular growth and granulosa cells molecular metabolism in donkeys (Equus asinus)

Vitamins and microelements play essential roles in mammalian ovarian physiology, including follicle development, ovulation, and synthesis and secretion of hormones and growth factors. However, it is nevertheless elusive to what extent exogenous supplementation with mixtures of vitamins ADE, zinc (Zn), and selenium (Se) affects follicular growth and granulosa cells (GCs) molecular function. We herein investigated their effect on follicular growth and GCs physiological function. We showed that follicular growth and ovulation time was accelerated and shortened with the increases of vitamins ADE, Zn, and Se doses by continually monitoring and recording (one estrus cycle of about 21 days) with an ultrasound scanner. Integrated omics analysis showed that there was a sophisticated network relationship, correlation expression, and enrichment pathways of the genes and metabolites highly related to organic acids and their derivatives and lipid-like molecules. Quantitative real-time PCR (qPCR) results showed that vitamin D receptor (VDR), transient receptor potential cation channel subfamily m member 6 (TRPM6), transient receptor potential cation channel subfamily v member 6 (TRPV6), solute carrier family 5 member 1 (SLC5A1), arachidonate 5-lipoxygenase (ALOX5), steroidogenic acute regulatory protein (STAR), prostaglandin-endoperoxide synthase 2 (PTGS2), and insulin like growth factor 1 (IGF-1) had a strong correlation between the transcriptome data. Combined multi-omics analysis revealed that the protein digestion and absorption, ABC transporters, biosynthesis of amino acids, aminoacyl-tRNA biosynthesis, mineral absorption, alanine, aspartate and glutamate metabolism, glycine, serine and threonine metabolism, arginine biosynthesis, and ovarian steroidogenesis were significantly enriched. We focused on the gene-metabolite interactions in ovarian steroidogenesis, founding that insulin receptor (INSR), phospholipase a2 group IVA (PLA2G4A), adenylate cyclase 6 (ADCY6), cytochrome p450 family 1 subfamily b member 1 (CYP1B1), protein kinase camp-activated catalytic subunit beta (PRKACB), cytochrome p450 family 17 subfamily a member 1 (CYP17A1), and phospholipase a2 group IVF (PLA2G4F) were negatively correlated with β-estradiol (E2), progesterone (P4), and testosterone (T) (P < 0.05). while ALOX5 was a positive correlation with E2, P4, and T (P < 0.05); cytochrome p450 family 19 subfamily a member 1 (CYP19A1) was a negative correlation with cholesterol (P < 0.01). In mineral absorption, our findings further demonstrated that there was a positive correlation between solute carrier family 26 member 6 (SLC26A6), SLC5A1, and solute carrier family 6 member 19 (SLC6A19) with Glycine and L-methionine. Solute carrier family 40 member 1 (SLC40A1) was a negative correlation with Glycine and L-methionine (P < 0.01). TRPV6 and ATPase Na+/K+ transporting subunit alpha 1 (ATP1A1) were positively associated with Glycine (P < 0.05); while ATPase Na+/K+ transporting subunit beta 3 (ATP1B3) and cytochrome b reductase 1 (CYBRD1) were negatively related to L-methionine (P < 0.05). These outcomes suggested that the vitamins ADE, Zn, and Se of mixtures play an important role in the synthesis and secretion of steroid hormones and mineral absorption metabolism pathway through effects on the expression of the key genes and metabolites in GCs. Meanwhile, these also are required for physiological function and metabolism of GCs. Collectively, our outcomes shed new light on the underlying mechanisms of their effect on follicular growth and GCs molecular physiological function, helping explore valuable biomarkers.

Proteomics and bioinformatics analysis of follicular fluid from patients with polycystic ovary syndrome

Objectives: Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder with heterogeneous manifestations and complex etiology. We used quantitative proteomics analysis based on mass spectrometry to identify the differences in proteomics profiles for follicular fluid obtained from patients with or without PCOS and explore possible mechanisms underlying PCOS.

Methods: Follicular fluid samples were collected from infertile patients with (n = 9) or without (n = 9) PCOS. Total protein was extracted, quantitatively labeled with a tandem mass tag (TMT), and analyzed using liquid chromatography-mass spectrometry (LC‐MS). TMT-based proteomics and bioinformatics analysis were used to determine the differentially expressed proteins (DEPs) and understand the protein networks. The analysis included protein annotation, unsupervised hierarchical clustering, functional classification, functional enrichment and clustering, and protein-protein interaction analysis. Selected DEPs were confirmed by ELISA, and correlation analysis was performed between these DEPs and the clinical characteristics.

Results: In this study, we have identified 1,216 proteins, including 70 DEPs (32 upregulated proteins, 38 downregulated proteins). Bioinformatics analysis revealed that the inflammatory response, complement and coagulation cascades, activation of the immune response, lipid transport, and regulation of protein metabolic processes were co-enriched in patients with PCOS. Based on ELISA results, insulin-like growth factor binding protein 1 (IGFBP1) and apolipoprotein C2 (APOC2) were differentially expressed between patients with and without PCOS. Follicular IGFBP1 showed a positive correlation with the serum levels of high-density lipoprotein cholesterol (HDL-C) (r = 0.3046, p = 0.0419), but negatively correlated with the serum levels of anti-Müllerian hormone (AMH) (r = –0.2924, p = 0.0354) and triglycerides (r = –0.3177, p = 0.0246). Follicular APOC2 was negatively correlated with the serum apolipoprotein A1 (APOA1) levels (r = 0.4509, p = 0.0002).

Conclusion: Our study identified DEPs in the follicular fluid of patients with PCOS. Inflammatory response, complement and coagulation cascades, activation of the immune response, lipid transport, and regulation of protein metabolic process were deregulated in PCOS, which may play essential roles in the pathogenesis of PCOS.

Preovulatory serum estradiol concentration is positively associated with oocyte ATP and follicular fluid metabolite abundance in lactating beef cattle

Cattle induced to ovulate a small, physiologically immature preovulatory follicle had reduced oocyte developmental competence that resulted in decreased embryo cleavage and day 7 embryo quality compared with animals induced to ovulate a more advanced follicle. RNA-sequencing was performed on oocytes and their corresponding cumulus cells approximately 23 h after gonadotropin-releasing hormone (GnRH) administration to induce the preovulatory gonadotropin surge suggested reduced capacity for glucose metabolism and oxidative phosphorylation in the cumulus cells and oocytes from follicles ≤11.7 mm, respectively. We hypothesized that induced ovulation of a small, physiologically immature preovulatory follicle results in a suboptimal follicular microenvironment and reduced oocyte metabolic capacity. We performed a study with the objective to determine the impact of preovulatory follicle diameter and serum estradiol concentration at GnRH administration on oocyte metabolic competence and follicular fluid metabolome profiles. We synchronized the development of a preovulatory follicle and collected the follicle contents via transvaginal aspiration approximately 19 h after GnRH administration in lactating beef cows (n = 319). We determined ATP levels and mitochondrial DNA (mtDNA) copy number in 110 oocytes and performed ultra-high-performance liquid chromatography–high resolution mass spectrometry metabolomic studies on 45 follicular fluid samples. Intraoocyte ATP and the amount of ATP produced per mtDNA copy number were associated with serum estradiol concentration at GnRH and time from GnRH administration to follicle aspiration (P < 0.05). mtDNA copy number was not related to follicle diameter at GnRH, serum estradiol concentration at GnRH, or any potential covariates (P > 0.10). We detected 90 metabolites in the aspirated follicular fluid. We identified 22 metabolites associated with serum estradiol concentration at GnRH and 63 metabolites associated with follicular fluid progesterone concentration at the time of follicle aspiration (FDR < 0.10). Pathway enrichment analysis of significant metabolites suggested altered proteinogenesis, citric acid cycle, and pyrimidine metabolism in follicles of reduced estrogenic capacity pre-gonadotropin surge or reduced progesterone production by the time of follicle aspiration.

Lipid metabolism and endometrial receptivity

BACKGROUND

Obesity has now been recognized as a high-risk factor for reproductive health. Although remarkable advancements have been made in ART, a considerable number of infertile obese women still suffer from serial implantation failure, despite the high quality of embryos transferred. Although obesity has long been known to exert various deleterious effects on female fertility, the underlying mechanisms, especially the roles of lipid metabolism in endometrial receptivity, remain largely elusive.

OBJECTIVE AND RATIONALE

This review summarizes current evidence on the impacts of several major lipids and lipid-derived mediators on the embryonic implantation process. Emerging methods for evaluating endometrial receptivity, for example transcriptomic and lipidomic analysis, are also discussed.

SEARCH METHODS

The PubMed and Embase databases were searched using the following keywords: (lipid or fatty acid or prostaglandin or phospholipid or sphingolipid or endocannabinoid or lysophosphatidic acid or cholesterol or progesterone or estrogen or transcriptomic or lipidomic or obesity or dyslipidemia or polycystic ovary syndrome) AND (endometrial receptivity or uterine receptivity or embryo implantation or assisted reproductive technology or in vitro fertilization or embryo transfer). A comprehensive literature search was performed on the roles of lipid-related metabolic pathways in embryo implantation published between January 1970 and March 2022. Only studies with original data and reviews published in English were included in this review. Additional information was obtained from references cited in the articles resulting from the literature search.

OUTCOMES

Recent studies have shown that a fatty acids-related pro-inflammatory response in the embryo-endometrium boundary facilitates pregnancy via mediation of prostaglandin signaling. Phospholipid-derived mediators, for example endocannabinoids, lysophosphatidic acid and sphingosine-1-phosphate, are associated with endometrial receptivity, embryo spacing and decidualization based on evidence from both animal and human studies. Progesterone and estrogen are two cholesterol-derived steroid hormones that synergistically mediate the structural and functional alterations in the uterus ready for blastocyst implantation. Variations in serum cholesterol profiles throughout the menstrual cycle imply a demand for steroidogenesis at the time of window of implantation (WOI). Since 2002, endometrial transcriptomic analysis has been serving as a diagnostic tool for WOI dating. Numerous genes that govern lipid homeostasis have been identified and, based on specific alterations of lipidomic signatures differentially expressed in WOI, lipidomic analysis of endometrial fluid provides a possibility for non-invasive diagnosis of lipids alterations during the WOI.

WIDER IMPLICATIONS

Given that lipid metabolic dysregulation potentially plays a role in infertility, a better understanding of lipid metabolism could have significant clinical implications for the diagnosis and treatment of female reproductive disorders.

Comparative analyses in transcriptome of human granulosa cells and follicular fluid micro-environment between poor ovarian responders with conventional controlled ovarian or mild ovarian stimulations

BACKGROUND

Both mild and conventional controlled ovarian stimulation are the frequently used protocols for poor ovarian responders. However, there are some debates about which treatment is better. Moreover, little is known about the follicular physiology after the two ovarian stimulation protocols. This study was intended to investigate the features in granulosa cells and follicular fluid micro-environment after the two different ovarian stimulation protocols in poor responders.

METHODS

Granulosa cells RNA were sequenced using Illumina Hiseq technology. Specific differently expressed genes and proteins were verified by real-time quantitative PCR and Western blot analysis. Moreover, hormone and cytokine concentrations in the follicular fluid were measured by electrochemiluminescence immunoassay and enzyme-linked immunoabsorbent assay. The correlation between the results of molecular experiments and the laboratory outcomes were analyzed by Spearman correlation analysis.

RESULTS

The differentially expressed genes between the two groups were involved in 4 signaling pathways related to the follicular development; three proteins pertinent to the TGF-β signaling pathway were expressed differently in granulosa cells between the two, and the constituents in the follicular fluid were also different. Further, a correlation between the TGF-β signaling pathway and the good-quality embryo was observed.

CONCLUSIONS

The present study made a comparison for the first time in the transcriptome of human granulosa cells and the follicular fluid micro-environment between poor responders with the conventional controlled ovarian stimulation or the mild ovarian stimulation, showing that the TGF-β signaling pathway may correlate with the good-quality of embryos in the mild group, which may be instrumental to the choice of optimal management for IVF patients.

A genome-wide association study of mare fertility in the Pura Raza Español horse

Despite the economic importance of fertility for the horse industry, few efforts have been made to achieve a better understanding of the genetic mechanisms underlying its control. This is probably due to the difficulty of obtaining reliable phenotypes and the complexity of modelling the environmental and management factors. This work is novel in that we propose to use reproductive efficiency (RE) as an indicator of mare fertility. To achieve this, we performed a genome-wide association study in the Pura Raza Español horse aimed at identifying genomic variants, regions, and candidate genes associated with fertility in mares. The dataset included 819 animals genotyped with the Affymetrix Axiom™ Equine 670 K single-nucleotide polymorphisms (SNPs) Genotyping Array and the deregressed breeding values for RE trait, obtained using a ssBLUP model, employed as pseudo-phenotypic data. Our results showed 28 SNPs potentially associated with RE, which explained 87.19% of the genetic variance and 6.61% of the phenotypic variance. Those results were further validated in BayesB, showing a correlation between observed and predicted RE of 0.57. In addition, 15 candidate genes (HTRA3, SPIRE1, APOE, ERCC1, FOXA3, NECTIN-2, KLC3, RSPH6A, PDPK1, MEIOB, PAQR4, NM3, PKD1, PRSS21, IFT140) previously related to fertility in mammals were associated with the markers and genomic regions significantly associated with RE. To our knowledge, this is the first genome-wide association study performed on mare fertility.

Age-associated changes in cumulus cells and follicular fluid: the local oocyte microenvironment as a determinant of gamete quality

The ovary is the first organ to age in humans with functional decline evident already in women in their early 30s. Reproductive aging is characterized by a decrease in oocyte quantity and quality, which is associated with an increase in infertility, spontaneous abortions, and birth defects. Reproductive aging also has implications for overall health due to decreased endocrinological output. Understanding the mechanisms underlying reproductive aging has significant societal implications as women globally are delaying childbearing and medical interventions have greatly increased the interval between menopause and total lifespan. Age-related changes inherent to the female gamete are well-characterized and include defects in chromosome and mitochondria structure, function, and regulation. More recently, it has been appreciated that the extra-follicular ovarian environment may have important direct or indirect impacts on the developing gamete, and age-dependent changes include increased fibrosis, inflammation, stiffness, and oxidative damage. The cumulus cells and follicular fluid that directly surround the oocyte during its final growth phase within the antral follicle represent additional critical local microenvironments. Here we systematically review the literature and evaluate the studies that investigated the age-related changes in cumulus cells and follicular fluid. Our findings demonstrate unique genetic, epigenetic, transcriptomic, and proteomic changes with associated metabolomic alterations, redox status imbalance, and increased apoptosis in the local oocyte microenvironment. We propose a model of how these changes interact, which may explain the rapid decline in gamete quality with age. We also review the limitations of published studies and highlight future research frontiers.

Arachidonic Acid in Follicular Fluid of PCOS Induces Oxidative Stress in a Human Ovarian Granulosa Tumor Cell Line (KGN) and Upregulates GDF15 Expression as a Response

Polycystic ovarian ovary syndrome (PCOS) is the main cause of ovulatory infertility and a common reproductive endocrine disease of women in reproductive age. In addition, nearly half of PCOS patients are associated with obesity, and their total free fatty acids tend to increase. Arachidonic acid (AA) is a polyunsaturated fatty acid. Oxidation products of AA reacting with various enzymes[cyclooxygenases (COX), lipoxygenases (LOX), cytochrome P450s (CYP)] can change cellular mitochondrial distribution and calcium ion concentration, and increase reactive oxygen species (ROS) production. In this study, we analyzed the follicular fluid fatty acids and found higher levels of C20:4n6 (AA) in PCOS patients than in normal control subjects. Also, to determine whether AA induces oxidative stress (OS) in the human ovarian granulosa tumor cell line (KGN) and affects its function, we treated KGN cells with or without reduced glutathione (GSH) and then stimulated them with AA. The results showed that AA significantly reduced the total antioxidant capacity (TAC) and activity of antioxidant enzymes and increased the malondialdehyde (MDA), ROS and superoxide anion(O_2-)levels in KGN cells. In addition, AA was also found to impair the secretory and mitochondrial functions of KGN cells and induce their apoptosis. We further investigated the downstream genes affected by AA in KGN cells and its mechanism of action. We found that AA upregulated the expression of growth differentiation factor 15 (GDF15), which had a protective effect on inflammation and tissue damage. Therefore, we investigated whether AA-induced OS in KGN cells upregulates GDF15 expression as an OS response.Through silencing of GDF15 and supplementation with recombinant GDF15 (rGDF15), we found that GDF15, expressed as an OS response, protected KGN cells against AA-induced OS effects, such as impairment of secretory and mitochondrial functions and apoptosis. Therefore, this study suggested that AA might induce OS in KGN cells and upregulate the expression of GDF15 as a response to OS.

The Role of ApoE Expression and Variability of Its Glycosylation in Human Reproductive Health in the Light of Current Information

Apolipoprotein E (ApoE), a 34-kDa glycoprotein, as part of the high-density lipoprotein (HDL), has antioxidant, anti-inflammatory and antiatherogenic properties. The variability of ApoE expression in the course of some female fertility disorders (endometriosis, POCS), and other gynecological pathologies such as breast cancer, choriocarcinoma, endometrial adenocarcinoma/hyperplasia and ovarian cancer confirm the multidirectional biological function of ApoE, but the mechanisms of its action are not fully understood. It is also worth taking a closer look at the associations between ApoE expression, the type of its genotype and male fertility disorders. Another important issue is the variability of ApoE glycosylation. It is documented that the profile and degree of ApoE glycosylation varies depending on where it occurs, the type of body fluid and the place of its synthesis in the human body. Alterations in ApoE glycosylation have been observed in the course of diseases such as preeclampsia or breast cancer, but little is known about the characteristics of ApoE glycans analyzed in human seminal and blood serum/plasma in the context of male reproductive health. A deeper analysis of ApoE glycosylation in the context of female and male fertility will both enable us to broaden our knowledge of the biochemical and cellular mechanisms in which glycans participate, having a direct or indirect relationship with the fertilization process, and also give us a chance of contributing to the enrichment of the diagnostic panel in infertile women and men, which is particularly important in procedures involved in assisted reproductive techniques. Moreover, understanding the mechanisms of glycoprotein glycosylation related to the course of various diseases and conditions, including infertility, and the interactions between glycans and their specific ligands may provide us with an opportunity to interfere with their course and thus develop new therapeutic strategies. This brief overview details some of the recent advances, mainly from the last decade, in understanding the associations between ApoE expression and some female and male fertility problems, as well as selected female gynecological diseases and male reproductive tract disorders. We were also interested in how ApoE glycosylation changes influence biological processes in the human body, with special attention to human fertility.

Correlation between steroid levels in follicular fluid and hormone synthesis related substances in its exosomes and embryo quality in patients with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is an endocrine and metabolic disorder with various manifestations and complex etiology. Follicular fluid (FF) serves as the complex microenvironment for follicular development. However, the correlation between the concentration of steroid in FF and the pathogenesis of PCOS is still unclear.

METHODS

Twenty steroid levels in FF from ten patients with PCOS and ten women with male-factor infertility undergoing in vitro fertilization were tested by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to explore their possibly correlation with PCOS. Meanwhile, the mRNA levels of core enzymes in steroid synthesis pathway from exosomes of FF were also detected by qPCR.

RESULTS

The estriol (p < 0.01), estradiol (p < 0.05) and prenenolone (p < 0.01) levels in FF of PCOS group were significantly increased, compared to the normal group, and the progesterone levels (p < 0.05) were decreased in PCOS group. Increased mRNA levels of CYP11A, CYP19A and HSD17B2 of exosomes were accompanied by the hormonal changes in FF. Correlation analysis showed that mRNA levels of CYP11A and HSD17B2 were negatively correlated with percent of top-quality embryos and rate of embryos develop to blastocyst.

CONCLUSION

Our results suggest that increased levels of estrogen and pregnenolone in follicular fluid may affect follicle development in PCOS patients, and the mechanism is partially related to HSD17B1, CYP19A1 and CYP11A1 expression change in FF exosomes.

Increased ApoE Expression in Follicular Fluid and the ApoE Genotype Are Associated With Endometriosis in Chinese Women

More than 10% of women suffer from endometriosis (EMT) during their reproductive years. EMT can cause pain and infertility and requires further study from multiple perspectives. Previous reports have indicated that an increase inapolipoprotein E (ApoE) may be associated with a lower number of retrieved mature oocytes in older women, and an association between ApoE and spontaneous pregnancy loss may exist in patients with EMT. The purpose of this study was to investigate the existence of an increase in ApoE in follicular fluid (FF) and the possible relationship between ApoE and EMT in Chinese women. In the current study, 217 Chinese women (111 control subjects and 106 EMT patients) were included. The ApoE genotypes were identified by Sanger sequencing. We found that ApoE expression in FF was higher in patients with EMT than in the control group. In addition, a significant difference in ApoE4 carriers (ϵ3/ϵ4, ϵ4/ϵ4) was found between the control subjects and the patients with EMT. Furthermore, a nonparametric test revealed significant differences in the numbers of blastocysts and high-quality blastocysts, but not the hormone levels of FSH, LH, and E2, between the two groups. We also established a multifactor (BMI, high-quality blastocysts, and ϵ4) prediction model with good sensitivity for identifying patients who may suffer from EMT. Our results demonstrate that ApoE expression in FF is increased in EMT, the ApoE-ϵ4 allele is significantly linked to EMT, and a combined analysis of three factors (BMI, high-quality blastocysts, and ϵ4) could be used as a predictor of EMT.

Apolipoprotein E Effects on Mammalian Ovarian Steroidogenesis and Human Fertility

Apolipoprotein E (ApoE) is a glycoprotein consisting of 299 amino acids, highly produced in the mammalian ovaries. The main function of the ApoE is to transport cholesterol from the peripheral tissues to be metabolized in the liver. In humans, the ApoE gene is polymorphic, with three alleles in a single chromosome-19 locus: APOE2, APOE3, and APOE4. ApoE has also been implicated in cholesterol transport within ovarian follicles to regulate steroidogenesis. Ovarian thecal and granulosa cell cholesterol uptake requires ApoE either by participating in the lipoprotein-receptor complex or lipid endocytosis. In this review, we summarize ApoE role on mammalian ovarian steroidogenesis and on human fertility and discuss recent findings of ApoE4 as an antagonistic pleiotropy gene under adverse environments.

A Shift in Glycerolipid Metabolism Defines the Follicular Fluid of IVF Patients with Unexplained Infertility

Follicular fluid (FF) constitutes the microenvironment of the developing oocyte. We recently characterized its lipid composition and found lipid signatures of positive pregnancy outcome after in vitro fertilization (IVF). In the current study, we aimed to test the hypothesis that unexplained female infertility is related to lipid metabolism, given the lipid signature of positive-outcome IVF patients we previously found. Assuming that FF samples from IVF patients with male factor infertility can represent a non-hindered metabolic microenvironment, we compared them to FF taken from women with unexplained infertility. FF from patients undergoing IVF was examined for its lipid composition. We found highly increased triacylglycerol levels, with a lower abundance of monoacylglycerols, phospholipids and sphingolipids in the FF of patients with unexplained infertility. The alterations in the lipid class accumulation were independent of the body mass index (BMI) and were altogether kept across the age groups. Potential lipid biomarkers for pregnancy outcomes showed a highly discriminative abundance in the FF of unexplained infertility patients. Lipid abundance distinguished IVF patients with unrecognized infertility and provided a potential means for the evaluation of female fertility.

Beyond the CNS: The many peripheral roles of APOE

Apolipoprotein E (APOE) is a multifunctional protein synthesized and secreted by multiple mammalian tissues. Although hepatocytes contribute about 75% of the peripheral pool, APOE can also be expressed in adipose tissue, the kidney, and the adrenal glands, among other tissues. High levels of APOE production also occur in the brain, where it is primarily synthesized by glia, and peripheral and brain APOE pools are thought to be distinct. In humans, APOE is polymorphic, with three major alleles (ε2, ε3, and ε4). These allelic forms dramatically alter APOE structure and function. Historically, the vast majority of research on APOE has centered on the important role it plays in modulating risk for cardiovascular disease and Alzheimer's disease. However, the established effects of this pleiotropic protein extend well beyond these two critical health challenges, with demonstrated roles across a wide spectrum of biological conditions, including adipose tissue function and obesity, metabolic syndrome and diabetes, fertility and longevity, and immune function. While the spectrum of biological systems in which APOE plays a role seems implausibly wide at first glance, there are some potential unifying mechanisms that could tie these seemingly disparate disorders together. In the current review, we aim to concisely summarize a wide breadth of APOE-associated pathologies and to analyze the influence of APOE in the development of several distinct disorders in order to provide insight into potential shared mechanisms implied in these various pathophysiological processes.

Lipid levels after childbirth and association with number of children: A population-based cohort study

OBJECTIVE

Low parity women are at increased risk of cardiovascular mortality. Unfavourable lipid profiles have been found in one-child mothers years before they conceive. However, it remains unclear whether unfavourable lipid profiles are evident in these women also after their first birth. The aim was to estimate post-pregnancy lipid levels in one-child mothers compared to mothers with two or more children and to assess these lipid's associations with number of children.

METHODS

We used data on 32 618 parous women (4 490 one-child mothers and 28 128 women with ≥2 children) examined after first childbirth as part of Cohort of Norway (1994-2003) with linked data on reproduction and number of children from the Medical Birth Registry of Norway (1967-2008). Odds ratios (ORs) with 95% confidence intervals (CIs) for one lifetime pregnancy (vs. ≥2 pregnancies) by lipid quintiles were obtained by logistic regression and adjusted for age at examination, year of first birth, body mass index, oral contraceptive use, smoking and educational level.

RESULTS

Compared to women with the lowest quintiles, ORs for one lifetime pregnancy for the highest quintiles of LDL and total cholesterol were 1.30 (95%CI: 1.14-1.45) and 1.43 (95%CI: 1.27-1.61), respectively. Sensitivity analysis (women <40 years) showed no appreciable change in our results. In stratified analyses, estimates were slightly stronger in overweight/obese, physically inactive and women with self-perceived bad health.

CONCLUSIONS

Mean lipid levels measured after childbirth in women with one child were significantly higher compared to mothers with two or more children and were associated with higher probability of having only one child. These findings corroborate an association between serum lipid levels and one lifetime pregnancy (as a feature of subfecundity), emphasizing that these particular women may be a specific predetermined risk group for cardiovascular related disease and death.

CoQ10 Supplementation in Patients Undergoing IVF-ET: The Relationship with Follicular Fluid Content and Oocyte Maturity

Background: The target of the reduced fecundity with aging is the oocyte. The follicular fluid and its components are strongly linked with the environment of the maturing oocyte. The aim of the present study was to evaluate CoQ10 bioavailability in follicular fluids after oral supplementation and its possible implication in oocyte maturation. Methods: Fifteen female partners of infertile couples, aged 31–46, undergoing IVF-ET and taking 200 mg/day oral CoQ10 were compared to unsupplemented patients. CoQ10 content, its oxidative status and total antioxidant capacity were evaluated also in relation to oocyte maturation indexes. Results: CoQ10 supplementation produced a significant increase in follicular content and a significant improvement of its oxidative status. Follicular fluid total antioxidant capacity highlighted a significant decrease in patients supplemented with CoQ10, specially in women >35 years. CoQ10 supplementation was associated with a significant decrease in total antioxidant capacity of fluid from follicles containing mature oocyte, moreover CoQ10 oxidative status was also significantly reduced but in follicles containing immature oocyte. Conclusions: Our observation leads to the hypothesis that the oral supplementation of CoQ10 may improve follicular fluid oxidative metabolism and oocyte quality, specially in over 35-year-old women.

Action mechanisms of n-3 polyunsaturated fatty acids on the oocyte maturation and developmental competence: Potential advantages and disadvantages

Infertility is a growing problem worldwide. Currently, in vitro fertilization (IVF) is widely performed to treat infertility. However, a high percentage of IVF cycles fails, due to the poor developmental potential of the retrieved oocyte to generate viable embryos. Fatty acid content of the follicular microenvironment can affect oocyte maturation and the subsequent developmental competence. Saturated and monounsaturated fatty acids are mainly used by follicle components as primary energy sources whereas polyunsaturated fatty acids (PUFAs) play a wide range of roles. A large body of evidence supports the beneficial effects of n-3 PUFAs in prevention, treatment, and amelioration of some pathophysiological conditions including heart diseases, cancer, diabetes, and psychological disorders. Nevertheless, current findings regarding the effects of n-3 PUFAs on reproductive outcomes in general and on oocyte quality more specifically are inconsistent. This review attempts to provide a comprehensive overview of potential molecular mechanisms by which n-3 PUFAs affect oocyte maturation and developmental competence, particularly in the setting of IVF and thereby aims to elucidate the reasons behind current discrepancies around this topic.

Women's prepregnancy lipid levels and number of children: a Norwegian prospective population-based cohort study

OBJECTIVE

To study prepregnancy serum lipid levels and the association with the number of children.

DESIGN

Prospective, population-based cohort.

SETTING

Linked data from the Cohort of Norway and the Medical Birth Registry of Norway.

PARTICIPANTS

2645 women giving birth to their first child during 1994-2003 (488 one-child mothers and 2157 women with ≥2 births) and 1677 nulliparous women.

MAIN OUTCOME MEASURES

ORs for no and one lifetime pregnancy (relative to ≥2 pregnancies) obtained by multinomial logistic regression, adjusted for age at examination, education, body mass index (BMI), smoking, time since last meal and oral contraceptive use.

RESULTS

Assessed in quintiles, higher prepregnant triglyceride (TG) and TG to high-density lipoprotein (TG:HDL-c) ratio levels were associated with increased risk of one lifetime pregnancy compared with having ≥2 children. Compared with the highest quintile, women in the lowest quintile of HDL cholesterol levels had an increased risk of one lifetime pregnancy (OR 1.7, 95% CI 1.2 to 2.4), as were women with the highest low-density lipoprotein (LDL) cholesterol, TG and TG:HDL-c ratio quintiles (compared with the lowest) (OR 1.2, 95% CI 0.8 to 1.7; OR 2.2, 95% CI 1.5 to 3.2; and OR 2.2, 95% CI 1.5 to 3.2, respectively). Similar effects were found in women with BMI≥25 and the highest LDL and total cholesterol levels in risk of lifetime nulliparity.

CONCLUSION

Women with unfavourable prepregnant lipid profile had higher risk of having no or only one child. These findings substantiate an association between prepregnant serum lipid levels and number of children. Previously observed associations between low parity and increased cardiovascular mortality may in part be due to pre-existing cardiovascular disease lipid risk factors.

Targeted metabolomics reveals reduced levels of polyunsaturated choline plasmalogens and a smaller dimethylarginine/arginine ratio in the follicular fluid of patients with a diminished ovarian reserve

STUDY QUESTION

Does the metabolomic profile of the follicular fluid (FF) of patients with a diminished ovarian reserve (DOR) differ from that of patients with a normal ovarian reserve (NOR)?

SUMMARY ANSWER

The metabolomic signature of the FF reveals a significant decrease in polyunsaturated choline plasmalogens and methyl arginine transferase activity in DOR patients compared to NOR patients.

WHAT IS KNOWN ALREADY

The composition of the FF reflects the exchanges between the oocyte and its microenvironment during its acquisition of gametic competence. Studies of the FF have allowed identification of biomarkers and metabolic pathways involved in various pathologies affecting oocyte quality, but no large metabolomic analysis in the context of ovarian ageing and DOR has been undertaken so far.

STUDY DESIGN, SIZE, DURATION

This was an observational study of the FF retrieved from 57 women undergoing in vitro fertilization at the University Hospital of Angers, France, from November 2015 to September 2016. The women were classified in two groups: one including 28 DOR patients, and the other including 29 NOR patients, serving as controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients were enrolled in the morning of oocyte retrieval after ovarian stimulation. Once the oocytes were isolated for fertilization and culture, the FF was pooled and centrifuged for analysis. A targeted quantitative metabolomic analysis was performed using high-performance liquid chromatography coupled with tandem mass spectrometry, and the Biocrates Absolute IDQ p180 kit. The FF levels of 188 metabolites and several sums and ratios of metabolic significance were assessed by multivariate and univariate analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 136 metabolites were accurately quantified and used for calculating 23 sums and ratios. Samples were randomly divided into training and validation sets. The training set, allowed the construction of multivariate statistical models with a projection-supervised method, i.e. orthogonal partial least squares discriminant analysis (OPLS-DA), applied to the full set of metabolites, or the penalized least absolute shrinkage and selection operator with logistic regression (LASSO-LR), applied to the ratios and sums of the metabolites. Both multivariate models showed good predictive performances when applied to the validation set. The final penalized model retained the three most significant variables, i.e. the total dimethylarginine-to-arginine ratio (Total DMA/Arginine), the sum of the polyunsaturated choline plasmalogens (PUFA ae), and the patient's age. The negative coefficients of Total DMA/Arginine and PUFA ae indicated that these FF variables had lower values in DOR patients than in NOR patients.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

This study presents two limitations. First, with this targeted metabolomics analysis, we have explored only a limited portion of the FF metabolome. Second, although the signature found was highly significant, the mechanism underlying the dysfunction remains undetermined.

WIDER IMPLICATIONS OF THE FINDINGS

The understanding of the mechanisms implied in ovarian ageing is essential for providing an adequate response to affected women desiring pregnancy. Our study proposes an incoming signature that may open new paths towards this goal.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the University Hospital of Angers, the University of Angers, and the French national research centers, INSERM and the CNRS. There were no competing interests.

Influence of follicular fluid and cumulus cells on oocyte quality: clinical implications

An equilibrium needs to be established by the cellular and acellular components of the ovarian follicle if developmental competence is to be acquired by the oocyte. Both cumulus cells (CCs) and follicular fluid (FF) are critical determinants for oocyte quality. Understanding how CCs and FF influence oocyte quality in the presence of deleterious systemic or pelvic conditions may impact clinical decisions in the course of managing infertility. Given that the functional integrities of FF and CCs are susceptible to concurrent pathological conditions, it is important to understand how pathophysiological factors influence natural fertility and the outcomes of pregnancy arising from the use of assisted reproduction technologies (ARTs). Accordingly, this review discusses the roles of CCs and FF in ensuring oocyte competence and present new insights on pathological conditions that may interfere with oocyte quality by altering the intrafollicular environment.

Differential long non-coding RNA expression profiles in human oocytes and cumulus cells

Progress in assisted reproductive technologies strongly relies on understanding the regulation of the dialogue between oocyte and cumulus cells (CCs). Little is known about the role of long non-coding RNAs (lncRNAs) in the human cumulus-oocyte complex (COC). To this aim, publicly available RNA-sequencing data were analyzed to identify lncRNAs that were abundant in metaphase II (MII) oocytes (BCAR4, C3orf56, TUNAR, OOEP-AS1, CASC18, and LINC01118) and CCs (NEAT1, MALAT1, ANXA2P2, MEG3, IL6STP1, and VIM-AS1). These data were validated by RT-qPCR analysis using independent oocytes and CC samples. The functions of the identified lncRNAs were then predicted by constructing lncRNA-mRNA co-expression networks. This analysis suggested that MII oocyte lncRNAs could be involved in chromatin remodeling, cell pluripotency and in driving early embryonic development. CC lncRNAs were co-expressed with genes involved in apoptosis and extracellular matrix-related functions. A bioinformatic analysis of RNA-sequencing data to identify CC lncRNAs that are affected by maternal age showed that lncRNAs with age-related altered expression in CCs are essential for oocyte growth. This comprehensive analysis of lncRNAs expressed in human MII oocytes and CCs could provide biomarkers of oocyte quality for the development of non-invasive tests to identify embryos with high developmental potential.

Proteomic analysis of human follicular fluid associated with successful in vitro fertilization

BACKGROUND

Human follicular fluid (HFF) provides a key environment for follicle development and oocyte maturation, and contributes to oocyte quality and in vitro fertilization (IVF) outcome.

METHODS

To better understand folliculogenesis in the ovary, a proteomic strategy based on dual reverse phase high performance liquid chromatography (RP-HPLC) coupled to matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (LC-MALDI TOF/TOF MS) was used to investigate the protein profile of HFF from women undergoing successful IVF.

RESULTS

A total of 219 unique high-confidence (False Discovery Rate (FDR) < 0.01) HFF proteins were identified by searching the reviewed Swiss-Prot human database (20,183 sequences), and MS data were further verified by western blot. PANTHER showed HFF proteins were involved in complement and coagulation cascade, growth factor and hormone, immunity, and transportation, KEGG indicated their pathway, and STRING demonstrated their interaction networks. In comparison, 32% and 50% of proteins have not been reported in previous human follicular fluid and plasma.

CONCLUSIONS

Our HFF proteome research provided a new complementary high-confidence dataset of folliculogenesis and oocyte maturation environment. Those proteins associated with innate immunity, complement cascade, blood coagulation, and angiogenesis might serve as the biomarkers of female infertility and IVF outcome, and their pathways facilitated a complete exhibition of reproductive process.

Apolipoprotein B is regulated by gonadotropins and constitutes a predictive biomarker of IVF outcomes

BACKGROUND

Follicular fluid (FF) is an important micro-environment influencing oocyte growth, its development competence, and embryo viability. The FF content analysis allows to identify new relevant biomarkers, which could be predictive of in vitro fertilization (IVF) outcomes. Inside ovarian follicle, the amount of FF components from granulosa cells (GC) secretion, could be regulated by gonadotropins, which play a major role in follicle development.

METHODS

This prospective study included 61 female undergoing IVF or Intra-cytoplasmic sperm injection (ICSI) procedure. Apolipoprotein B (APOB) concentrations in follicular fluid and APOB gene and protein expression in granulosa cells from reproductively aged women undergoing an in vitro fertilization program were measured. The statistical analyses were performed according to a quartile model based on the amount of APOB level found in FF.

RESULTS

Amounts of APOB were detected in human FF samples (mean ± SD: 244.6 ± 185.9 ng/ml). The odds of obtaining an oocyte in the follicle and a fertilized oocyte increased significantly when APOB level in FF was higher than 112 ng/ml [i.e., including in Quartile Q 2, Q3 and Q4] (p = 0.001; p < 0.001, respectively). The probabilities of obtaining an embryo and a top quality embryo on day 2, were significantly higher if APOB levels were within the ranges of 112 and 330 ng/ml (i.e. in Q2 and Q3) or 112 and 230 ng/ml (i.e. in Q2), respectively (p < 0.001; p = 0.047, respectively). In addition, our experiments in vitro indicated that APOB gene and protein expression, along with APOB content into culture were significantly under-expressed in GC upon stimulation with gonadotropins (follicular stimulating hormone: FSH and/or human chorionic gonadotropin: hCG).

CONCLUSION

We are reporting a positive and statistically significant associations between APOB and oocyte retrieval, oocyte fertilization, and embryo quality. Using an experimental study component, the authors report significant reduced APOB expression and content for luteinized granulosa cells cultured in the presence of gonadotropins.

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.

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.

Lipids and oocyte developmental competence: the role of fatty acids and β-oxidation

Metabolism and ATP levels within the oocyte and adjacent cumulus cells are associated with quality of oocyte and optimal development of a healthy embryo. Lipid metabolism provides a potent source of energy and its importance during oocyte maturation is being increasingly recognised. The triglyceride and fatty acid composition of ovarian follicular fluid has been characterised for many species and is influenced by nutritional status (i.e. dietary fat, fasting, obesity and season) as well as lactation in cows. Lipid in oocytes is a primarily triglyceride of specific fatty acids which differ by species, stored in distinct droplet organelles that re-localise during oocyte maturation. The presence of lipids, particularly saturated vs unsaturated fatty acids, in in vitro maturation systems affects oocyte lipid content as well as developmental competence. Triglycerides are metabolised by lipases that have been localised to cumulus cells as well as oocytes. Fatty acids generated by lipolysis are further metabolised by β-oxidation in mitochondria for the production of ATP. β-oxidation is induced in cumulus–oocyte complexes (COCs) by the LH surge, and pharmacological inhibition of β-oxidation impairs oocyte maturation and embryo development. Promoting β-oxidation with l-carnitine improves embryo development in many species. Thus, fatty acid metabolism in the mammalian COC is regulated by maternal physiological and in vitro environmental conditions; and is important for oocyte developmental competence.

Metabolite Profiling in the Pursuit of Biomarkers for IVF Outcome: The Case for Metabolomics Studies

Background. This paper presents the literature on biomarkers of in vitro fertilisation (IVF) outcome, demonstrating the progression of these studies towards metabolite profiling, specifically metabolomics. The need for more, and improved, metabolomics studies in the field of assisted conception is discussed. Methods. Searches were performed on ISI Web of Knowledge SM for literature associated with biomarkers of oocyte and embryo quality, and biomarkers of IVF outcome in embryo culture medium, follicular fluid (FF), and blood plasma in female mammals. Results. Metabolomics in the field of female reproduction is still in its infancy. Metabolomics investigations of embryo culture medium for embryo selection have been the most common, but only within the last five years. Only in 2012 has the first metabolomics investigation of FF for biomarkers of oocyte quality been reported. The only metabolomics studies of human blood plasma in this context have been aimed at identifying women with polycystic ovary syndrome (PCOS). Conclusions. Metabolomics is becoming more established in the field of assisted conception, but the studies performed so far have been preliminary and not all potential applications have yet been explored. With further improved metabolomics studies, the possibility of identifying a method for predicting IVF outcome may become a reality.

Complement factors are secreted in human follicular fluid by granulosa cells and are possible oocyte maturation factors

AIMS

In this study, we identify components of the complement system present in human follicular fluid that affect oocyte development and maturation.

MATERIAL AND METHODS

Using bottom-up liquid chromatography/mass spectrometry/mass spectrometry, we identified complement factors as consistently present in human follicular fluid from 15 different subjects.

RESULTS

According to our gene-chip data, these complement factors are actively produced by granulosa cells.

CONCLUSIONS

By applying the computational Ingenuity Pathway Analysis software and database we have identified complement pathways that play a role in oocyte maturation and follicular development.

Two common polymorphisms in the peroxisome proliferator-activated receptor γ gene may improve fertilization in IVF

Genetic factors play an important role in women's fertility and embryonic development and may also contribute to the efficacy of assisted reproduction techniques. The aim of this study was to investigate the effect of His447His and Pro12Ala peroxisome proliferator-activated receptor γ (PPARγ) gene polymorphisms on oocytes and fertilization in women undergoing IVF. Follicular fluid and blood samples were obtained from 98 IVF patients referred to Tabriz Alzahra Hospital. Samples were analysed for fatty acid content by gas-liquid chromatography and for polymorphisms of the PPARγ gene using polymerase chain reaction-restriction fragment length polymorphism-based methods. Multiple regression analyses were used to test the independence of associations between the number of mature and fertilized oocytes as outcome variables and the polymorphisms of PPARγ gene. For both polymorphisms, fertilization ratio was significantly (P<0.05) higher in carriers of the rare alleles than homozygous wild-type genotypes. The associations of His447His (P=0.003) and Pro12Ala (P=0.015) polymorphisms remained statistically significant in the multiple regression analyses. This study suggests that the two common gene polymorphisms of PPARγ may improve fertilization in vitro and, thus possibly, female fertility.

Human luteinized granulosa cells secrete apoB100-containing lipoproteins

Thus far, liver, intestine, heart, and placenta have been shown to secrete apolipoprotein (apo)B-containing lipoproteins. In the present study, we first investigated lipoproteins in human follicular fluid (FF), surrounding developing oocytes within the ovary, as well as in corresponding plasma samples (n = 12). HDL cholesterol within FF correlated well with plasma HDL cholesterol (r = 0.80, P < 0.01), whereas VLDL cholesterol did not, indicating that VLDL in FF might originate directly from the granulosa cells producing FF. Primary human granulosa cells expressed apoB, microsomal triglyceride transfer protein, and apoE, but not the apoB-editing enzyme apobec-1. Using (3)H-leucine, we show that granulosa cells secrete apoB100-containing lipoproteins and that secretion can be stimulated by adding oleate to the medium (+83%). With electron microscopy, apoB-containing lipoproteins within the secretory pathway of human granulosa cells were directly visualized. Finally, we found a positive relationship between apoB levels in FF and improved fertility parameters in a population of 27 women undergoing in vitro fertilization. This study demonstrates that human granulosa cells assemble and secrete apoB100-containing lipoproteins, thereby identifying a novel cell type equipped with these properties. These results might have important implications for female infertility phenotypes as well as for the development of drugs targeting the VLDL production pathway.

Progesterone receptor-induced gene expression in primary mouse granulosa cell cultures

The progesterone receptor (PGR) is induced by luteinizing hormone (LH) in granulosa cells of preovulatory follicles, and the PGR-A isoform is essential for ovulation based on the phenotypes of Pgr isoform-specific knockout mice. Although several genes regulated by PGR-A in vivo have been identified, whether these genes are primary targets of PGR-A or if their expression also depends on other signaling molecules that are induced by the LH surge has not been resolved. Therefore, to identify genes that are either induced or repressed by PGR in the absence of LH-mediated signaling cascades, we infected primary cultures of mouse granulosa cells with either PGR-A or PGR-B adenoviral vectors without or with R-5020 as a PGR ligand. Total RNA was extracted from infected cells at 16 h and analyzed by Affymetrix Mouse 430 2.0 microarrays. PGR-A in the presence or absence of ligand significantly induced approximately 50 genes 2-fold or more (local pooled error test at P <or= 0.01). Fewer and different genes were induced by PGR-B in the absence of ligand. Edn1, Apoa1, and Cited1 were primarily regulated by PGR-A as verified by additional RT-PCR analyses, suppression by the PGR antagonist RU486, and the lack of induction by protein kinase A, protein kinase C, or epidermal growth factor (EGF)-like factors pathways. PGR regulation of these genes was confirmed further by gene expression analyses in hormonally primed Pgr mutant mouse ovaries. Because Edn1, Apoa1, and Cited1 are known to regulate angiogenesis, PGR may affect the neovascularization of follicles that is initiated with ovulation.