M. Schulte

IVF outcomes in obese donor oocyte recipients: a systematic review and meta-analysis

STUDY QUESTION Does obesity influence the chance of pregnancy after IVF in donor oocyte recipients? SUMMARY ANSWER The chance of pregnancy after IVF is no different in obese donor oocyte recipients versus those in the normal BMI range. WHAT IS KNOWN ALREADY Obesity is associated with decreased chances of pregnancy in women undergoing IVF with autologous oocytes. Prior studies have investigated the impact of obesity on IVF outcomes in donor oocyte recipients, with disparate results. This is the first systematic review and meta-analysis to address this topic. STUDY DESIGN, SIZE, DURATION A systematic review and meta-analysis of published literature identified in Medline, EMBASE and Scopus through December of 2011 were performed to address the association between BMI and outcomes for donor oocyte recipients. The primary outcome of this study was implantation. PARTICIPANTS/MATERIALS, SETTING, METHODS Two authors conducted the searches independently, selected the studies and abstracted the data. Studies in English of first donor oocyte cycles with reported recipient BMI were included. Primary data collected from the IVF program at Washington University were also included as one study (n = 123 donor oocyte recipients). Studies limited to frozen embryo transfer were excluded. Data were synthesized using DerSimonian-Laird random effects models for implantation, clinical pregnancy, miscarriage and live birth. MAIN RESULTS AND THE ROLE OF CHANCE Of 475 screened articles, 7 were reviewed and 5 were included together with primary data from Washington University, giving a total of 4758 women who were included for the assessment of the primary outcome. No associations between obesity (BMI ≥ 30 kg/m(2)) and chance of pregnancy after IVF were noted in women using donor oocytes [risk ratio (RR): 0.98, 95% confidence intervals (CI): 0.83-1.15, I(2): 61.6%]. Additional analyses assessing associations between recipient obesity and embryo implantation (RR: 0.93, 95% CI: 0.80-1.07, I(2): 0%), miscarriage (RR: 1.12, 95% CI: 0.83-1.50, I(2): 0%) and live birth (RR: 0.91, 95% CI: 0.65-1.27, I(2) 47.9%) also failed to show a negative effect. LIMITATIONS, REASONS FOR CAUTION Included studies were small and they were performed in a variety of locations and practice settings where stimulation and laboratory protocols may differ, and extremes of BMI may also differ. Furthermore, included studies had different inclusion and exclusion criteria. These factors could not be controlled for in this meta-analysis and statistical heterogeneity was noted for some outcomes. WIDER IMPLICATIONS OF THE FINDINGS These data suggest obesity does not affect IVF outcomes in women using donor oocytes. Oocyte quality rather than endometrial receptivity may be the overriding factor influencing IVF outcomes in obese women using autologous oocytes. STUDY FUNDING/COMPETING INTEREST(S) E.S.J. and M.G.T receive support from the Womens Reproductive Health Research Program sponsored by the National Institutes of Health (K12 HD063086). The authors do not have any competing interests. TRIAL REGISTRATION NUMBER N/A.

Obesity and PCOS The Effect of Metabolic Derangements on Endometrial Receptivity at the Time of Implantation

Successful embryonic implantation is the result of a receptive endometrium, a functional embryo at the blastocyst stage and a synchronized dialog between maternal and embryonic tissues. Successful implantation requires the endometrium to undergo steroid-dependent change during each menstrual cycle, exhibiting a short period of embryonic receptivity known as the window of implantation. The term “endometrial receptivity” was introduced to define the state of the endometrium during the window of implantation. It refers to the ability of the endometrium to undergo changes that will allow the blastocyst to attach, penetrate, and induce localized changes in the endometrial stroma. These changes are metabolically demanding, and glucose metabolism has been proven to be important for the preparation of the endometrium for embryo implantation. Obesity and polycystic ovary syndrome (PCOS) represent 2 common metabolic disorders that are associated with subfertility. The aim of this review is to summarize the effect of obesity and PCOS on endometrial receptivity at the time of implantation. Focus will be on metabolic alterations that regulate decidualization, including glucose metabolism, hyperinsulinemia, and hyperandrogenism.

Diet-induced obesity impairs endometrial stromal cell decidualization: a potential role for impaired autophagy

STUDY QUESTION What effect does diet-induced obesity have on endometrial stromal cell (ESC) decidualization? SUMMARY ANSWER Diet-induced obesity impairs ESC decidualization. WHAT IS KNOWN ALREADY Decidualization is important for successful implantation and subsequent health of the pregnancy. Compared with normal-weight women, obese women have lower pregnancy rates (both spontaneous and by assisted reproductive technology), higher rates of early pregnancy loss and poorer oocyte quality. STUDY DESIGN, SIZE, DURATION Beginning at 6 weeks of age, female C57Bl/6J mice were fed either a high-fat/high-sugar diet (HF/HS; 58% Fat Energy/Sucrose) or a diet of standard mouse chow (CON; 13% Fat) for 12 weeks. At this point, metabolic parameters were measured. Some of the mice (n = 9 HF/HS and 9 CON) were mated with reproductively competent males, and implantation sites were assessed. Other mice (n = 11 HF/HS and 10 CON) were mated with vasectomized males, and artificial decidualization was induced. For in vitro human studies of primary ESCs, endometrial tissue was obtained via biopsy from normo-ovulatory patients without history of infertility (obese = BMI > 30 kg/m(2), n = 11 and lean = BMI < 25 kg/m(2), n = 7) and from patients consented for hysterectomies for a benign indication (n = 4). In vitro studies were also performed with immortalized human ESCs. ESCs were decidualized in culture for nine 9 days in the presence or absence of palmitic acid (PA), and the degree of decidualization was assessed by measuring expression of decidualization markers. PARTICIPANTS/MATERIALS, SETTING, METHODS The sizes of implantation sites and fetuses were analyzed in mice mated with reproductively competent males. In mice mated with vasectomized males, decidualization was induced, and uterine tissues were analyzed via hematoxylin and eosin staining, quantitative RT-PCR (RT-qPCR), and western blots. Human ESCs were cultured in vitro and induced to decidualize by treatment with cAMP and medroxyprogesterone. The level of expression of decidualization markers was assessed by RT-qPCR (mRNA) and western blotting (protein). ATP content of ESCs was measured, and levels of autophagy were assessed by western blotting of the autophagy regulators acetyl coa carboxylase (ACC) and ULK1 (Ser 317). Autophagic flux was measured by western blot of the marker LC3b-II. MAIN RESULTS AND THE ROLE OF CHANCE Mice exposed to an HF/HS diet became obese and metabolically impaired. HF/HS-exposed mice mated to reproductively competent males had smaller implantation sites in early pregnancy (P <0.001) and larger fetuses at term (P <0.05) than CON-exposed mice. In the artificial decidualization experiments, mice exposed to the HF/HS diet developed 50% smaller deciduomas than mice exposed to CON diet (P< 0.001). Human ESCs cultured in the presence of PA had markedly decreased mRNA expression of the decidualization markers, decidual prolactin (PRL) (P< 0.0001) and insulin-like growth factor binding protein 1 (IGFBP1) (P< 0.0001). Expression of PRL and IGFBP1 by mRNA were also significantly lower in early follicular phase ESCs of obese women than in those of normal-weight women (P< 0.05). Protein expression of phosphorylated ACC and phosphorylated ULK1, both activated forms, were lower in deciduomas of HF/HS mice than in those of control mice (P < 0.01). In immortalized human ESCs, LC3b-II levels were higher in decidualized cells than in controls, indicating increased autophagy. PA treatment abrogated this increase. LIMITATIONS, REASONS FOR CAUTION Many aspects of obesity and metabolic impairment could contribute to the decidualization defects observed in the HF/HS-exposed mice. Although our findings suggest that both autophagy and decidualization are impaired by exposure to PA, the underlying mechanisms should be elucidated. Finally, our human patient sample size was small. WIDER IMPLICATIONS OF THE FINDINGS Although many factors contribute to poor reproductive outcome and early pregnancy loss in obese women, our study suggests the importance of decidualization defects. Such defects may contribute to compromised endometrial receptivity and poor implantation. If defects in autophagy contribute to impaired decidualization, therapeutics could be developed to improve this process and thus improve implantation and pregnancy outcomes in obese women. STUDY FUNDING/COMPETING INTERESTS Grants include NIH 5T32HD040135-12 (J.S.R.), R01 HD065435 (K.H.M.), NIH T32 HD049305 (J.L.S.) and ACOG Research Grant (M.B.S.). The authors report no conflicts of interest.

The Fatty Acid Beta-Oxidation Pathway Is Important for Decidualization of Endometrial Stromal Cells in Both Humans and Mice

ABSTRACT Embryo implantation and development requires the endometrial stromal cells (ESCs) to undergo decidualization. This differentiation process requires glucose utilization, and blockade of the pentose phosphate pathway inhibits decidualization of ESCs both in vitro and in vivo. Glucose and fatty acids are energy substrates for many cell types, and fatty acid beta-oxidation is critical for embryo implantation. Here, we investigated whether beta-oxidation is required for decidualization of ESCs. As assessed by marker gene expression, decidualization of human primary ESCs was blocked by reducing activity of carnitine calmitoyltransferase I, the rate-limiting enzyme in beta-oxidation, either by short hairpin RNA-mediated silencing or by treatment with the inhibitor etomoxir. Ranolazine (RAN), a partial beta-oxidation inhibitor, blocked early decidualization of a human ESC line. However, decidualization resumed after several days, most likely due to a compensatory up-regulation of GLUT1 expression and an increase in glucose metabolism. Simultaneous inhibition of the beta-oxidation pathway with RAN and the pentose phosphate pathway with glucosamine (GlcN) impaired in vitro decidualization of human ESCs more strongly than inhibition of either pathway alone. These findings were confirmed in murine ESCs in vitro, and exposure to RAN plus GlcN inhibited decidualization in vivo in a deciduoma model. Finally, intrauterine implantation of time-release RAN and GlcN pellets reduced pup number. Importantly, pup number returned to normal after the end of the pellet-active period. This work indicates that both fatty acids and glucose metabolism pathways are important for ESC decidualization, and suggests novel pathways to target for the design of future nonhormonal contraceptives.

Glucosamine Inhibits Decidualization of Human Endometrial Stromal Cells and Decreases Litter Sizes in Mice

ABSTRACT Embryo implantation in the uterus depends on decidualization of the endometrial stromal cells (ESCs), and glucose utilization via the pentose phosphate pathway is critical in this process. We hypothesized that the amino sugar glucosamine may block the pentose phosphate pathway via inhibition of the rate-limiting enzyme glucose-6-phosphate dehydrogenase in ESCs and therefore impair decidualization and embryo implantation, thus preventing pregnancy. Both human primary and immortalized ESCs were decidualized in vitro in the presence of 0, 2.5, or 5 mM glucosamine for 9 days. Viability assays demonstrated that glucosamine was well tolerated by human ESCs. Exposure of human ESCs to glucosamine resulted in significant decreases in the activity and expression of glucose-6-phosphate dehydrogenase and in the mRNA expression of the decidual markers prolactin, somatostatin, interleukin-15, and left-right determination factor 2. In mouse ESCs, expression of the decidual marker Prp decreased upon addition of glucosamine. In comparison with control mice, glucosamine-treated mice showed weak artificial deciduoma formation along the stimulated uterine horn. In a complementary in vivo experiment, a 60-day-release glucosamine (15, 150, or 1500 μg) or placebo pellet was implanted in a single uterine horn of mice. Mice with a glucosamine pellet delivered fewer live pups per litter than those with a control pellet, and pup number returned to normal after the end of the pellet-active period. In conclusion, glucosamine is a nonhormonal inhibitor of decidualization of both human and mouse ESCs and of pregnancy in mice. Our data indicate the potential for development of glucosamine as a novel, reversible, nonhormonal contraceptive.