Ovarian hyperstimulation syndrome and assisted reproductive technologies: why some and not others?

Differential expression of alpha 2 macroglobulin in response to dietylstilbestrol and in ovarian carcinomas in chickens

BACKGROUND

Alpha 2 macroglobulin (A2M; also known as ovostatin), a homotetrameric protein with four disulfide-linked subunits, has the unique feature of inactivating/inhibiting most known proteases including serine-, threonine-, cysteine-, aspartic- and metalloproteases. In chickens, A2M has been identified and characterized biochemically, but little is known of its functional role(s) in the oviduct, hormonal regulation of expression or its expression in ovarian carcinomas in chickens. Therefore, we investigated estrogen regulation of A2M gene expression during development of the chicken oviduct, and its expression in normal and cancerous ovaries from chickens.

METHODS

To determine tissue-specific expression of A2M in chickens, we collected various organs from male and female chickens and performed RT-PCR analyses. To examine A2M gene expression in the oviduct of 1-week-old female chicks that received a subcutaneous implant of 15 mg DES in the abdominal region for 20 days, we performed RT-PCR, qPCR and in situ hybridization analyses using cDNAs from control- (n=5) and DES-treated oviducts (n=5), and then each segment of the oviduct from DES-treated chicks. To determine if A2M is a biomarker of ovarian cancer in hens, we collected cancerous (n=10) ovaries from a total of 136 chickens which had completely stopped egg-laying and performed RT-PCR and in situ hybridization analyses.

RESULTS

We found that A2M is most abundant in the chicken oviduct, specifically luminal (LE) and glandular epithelia (GE), but it was not detected in any other tissues of either sex. We then determined that DES (dietylstilbestrol, a synthetic nonsteroidal estrogen) increased A2M mRNA only in LE and GE of the oviduct of chicks. Further, expression of A2M was most abundant in GE of endometrioid adenocarcinoma of cancerous, but not normal ovaries of hens.

CONCLUSIONS

Collectively, results of the present study indicate that A2M is novel estrogen-stimulated gene expressed in LE and GE of the chicken oviduct and may be used for monitoring effects of therapies for ovarian cancer in laying hens.

Two different entities of spontaneous ovarian hyperstimulation in a woman with FSH receptor mutation

Spontaneous ovarian hyperstimulation syndrome (OHSS) is an extremely rare event. Normally OHSS is seen in the context of IVF. In 2003 a mutation of the FSH receptor (FSHR D567N) was identified for the first time as a cause of spontaneous OHSS. In most FSHR mutations, a hypersensitivity to human chorionic gonadotrophin (HCG) or thyroid-stimulating hormone (TSH) is described. This clinical case presents for the first time two occurrences of spontaneous OHSS in a single woman with a FSHR mutation and two different entities. Pathophysiology of both pregnancies was completely different. During the first pregnancy, elevated HCG and androgen concentrations led to spontaneous OHSS and finally to miscarriage. The second pregnancy with spontaneous OHSS was dominated by a latent hypothyroidism and normal HCG concentrations and ended in a delivery of a healthy female newborn. Due to the unusual courses of the pregnancies, the study looked for a mutation in the FSHR and surprisingly identified the same mutation previously described. This report confirms for the first time the in-vitro findings in a single clinical case that TSH as well as HCG leads to spontaneous OHSS in patients with FSHR D567N mutation. Hypothyroidism has to be treated or ruled out.

Vascular endothelial growth factor levels in serum and plasma from patients undergoing controlled ovarian hyperstimulation for IVF

BACKGROUND

Vascular endothelial growth factor (VEGF) has been investigated as a marker of ovarian response to controlled ovarian hyperstimulation and as a predictor of ovarian hyperstimulation syndrome (OHSS) in IVF cycles. In most studies, serum has been used for circulating VEGF concentration measurement, but it has been suggested that plasma is the preferred medium to measure VEGF levels because of the potential contribution of VEGF released from platelets during blood clotting. This study investigated VEGF concentrations in paired serum and plasma samples from patients undergoing controlled ovarian hyperstimulation for IVF.

METHODS

Serum and plasma VEGF levels, as well as the number of platelets, were measured in 30 IVF patients who comprised three study groups delineated according to the estradiol (E(2)) serum concentration reached on the day of HCG administration: 10 patients having low E(2) serum levels (<1500 pg/ml, group L), 10 patients having intermediate E(2) serum levels (1500-3000 pg/ml, group I) and 10 patients having high E(2) serum levels (>3000 pg/ml, group H).

RESULTS

There was a statistically significant correlation between plasma and serum VEGF levels (rho = 0.61; P < 0.005) for the entire population studied, although serum values were higher by a factor of approximately 6-fold. No significant correlation was found between peripheral blood VEGF concentrations and serum E(2) or follicle number on HCG day or the number of oocytes collected. Similarly, paired serum and plasma VEGF measurements did not correlate with platelet count.

CONCLUSIONS

Serum and plasma VEGF concentrations are strongly correlated in paired samples from infertile patients undergoing controlled ovarian hyperstimulation. However, neither serum nor plasma VEGF levels were correlated with parameters associated with ovarian follicular activity. Peripheral blood VEGF levels were not correlated with platelet count.

Plasma levels of soluble vascular endothelial growth factor receptor-1 may determine the onset of early and late ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is a life-threatening condition associated with ovarian stimulation. Its pathophysiology is unknown and its treatment continues to be empirical. Early (E)- and late (L)-OHSS occur in women at risk, though not in all cases. Vascular endothelial growth factor (VEGF) is related to increased vascular permeability in OHSS. We analysed the dynamics of the VEGF system in E- and L-OHSS.

METHODS

A prospective cohort of women undergoing IVF-ICSI treatment were divided into groups. E-OHSS: Nonpregnant patients classified as women not at risk (group 1) (n = 11) and patients at risk who did not (group 2) (n = 18) and did (group 3) (n = 8) develop severe OHSS. Blood was drawn on the day of ovum retrieval (day 0) and 3, 6, 10 and 14 days later. L-OHSS: Single pregnancies classified as women who did not (group 4) (n = 8) and did develop (group 5) (n = 4) OHSS. Single pregnancies after oocyte donation (OD) (n = 4) were compared with groups 4 and 5 (IVF-ICSI). Blood was obtained weekly (weeks 4-12). Total VEGF (VEFG-A), free (f)-VEGF and soluble VEGF receptor 1 (sVEGFR-1) in plasma and in serum alpha2-macroglobulin (M) were also measured.

RESULTS

Group 3 showed significantly (P < 0.05) higher VEFG-A and f-VEGF than group 1 on day 6 because of lower sVEGFR-1 secretion. Similarly, group 5 had significantly (P < 0.05) more VEFG-A and f-VEGF and less sVEGFR-1 than group 4. Oocyte donation was associated with decreased sVEGFR-1 secretion, and alpha2M was not relevant in OHSS development.

CONCLUSION

In E- and L-OHSS, the ability to secrete sVEGFR-1 and bind VEGF seems to be the determinant factor in OHSS. f-VEGF acts locally in the ovary.

Incidence and prediction of ovarian hyperstimulation syndrome in women undergoing gonadotropin-releasing hormone antagonist in vitro fertilization cycles

OBJECTIVE

To determine the incidence of ovarian hyperstimulation syndrome (OHSS) in a large series of GnRH antagonist-stimulated cycles and to assess the predictive value of E2 and the number of follicles on the day of hCG administration.

DESIGN

Prospective cohort study of women undergoing IVF treatment with a GnRH antagonist protocol over a 2-year period.

SETTING

Tertiary university hospital.

PATIENT(S)

One thousand eight hundred one patients who underwent 2,524 cycles.

INTERVENTION(S)

Multifollicular ovarian stimulation with recombinant FSH and GnRH antagonist for IVF-ICSI treatment.

MAIN OUTCOME MEASURE(S)

Incidence of OHSS in GnRH antagonist cycles, predictive value of E2, and number of follicles on the day of hCG for OHSS occurrence.

RESULT(S)

Fifty-three patients were hospitalized because of OHSS (2.1%; 95% confidence interval [CI]:1.6-2.8). Early OHSS presented in 31 patients (1.2%; 95% CI: 0.9-1.8), whereas the late type was a complication in 22 patients (0.9%; 95% CI: 0.5-1.3). Late OHSS cases compared with the early OHSS cases always occurred in a pregnancy cycle (100% vs. 40%); had higher probability of being severe (72.7% vs. 42%), and more often were related to a multiple pregnancy (40% vs. 0). Receiver operating characteristic curve analysis for several E2 concentrations and number of follicles with a diameter of > or =11 mm revealed that the predictive value of the optimal threshold of > or =13 follicles (85.5% sensitivity; 69% specificity) was statistically significantly superior to the optimal threshold of 2,560 ng/L for E2 concentrations (53% sensitivity, 77% specificity) in identifying patients at risk for OHSS. Considering that severe OHSS represents the most clinically significant pattern, the combination of a threshold of > or =18 follicles and/or E2 of > or =5,000 ng/L yields a 83% sensitivity rate with a specificity as high as 84% for the severe OHSS cases.

CONCLUSION(S)

Clinically significant OHSS still remains a limitation of multifollicular ovarian stimulation for IVF even with the use of GnRH antagonist protocols. The number of follicles can discriminate the patients who are at risk for developing OHSS, whereas E2 concentrations are less reliable for the purpose of prediction. There is more than ever an urgent need for alternative final oocyte maturation-triggering medication.

Serum inhibin A, VEGF and TNFα levels after triggering oocyte maturation with GnRH agonist compared with HCG in women with polycystic ovaries undergoing IVF treatment: a prospective randomized trial

BACKGROUND

We aimed to examine the serum levels of inhibin A, vascular endothelial growth factor (VEGF), tumour necrosis factor alpha (TNFalpha), estradiol (E2) and progesterone levels after triggering of final oocyte maturation with GnRH agonist compared with HCG in patients with polycystic ovaries (PCO) and to investigate the relationship between these markers and ovarian hyperstimulation syndrome (OHSS).

METHODS

Twenty-eight patients with PCO, undergoing controlled ovarian hyperstimulation with FSH and GnRH antagonist for IVF-embryo transfer treatment, were randomized for triggering of final oocyte maturation with GnRH agonist (GnRH agonist group, n = 15) or HCG (HCG group, n = 13). Blood samples were obtained on the day of randomization and thereafter every 2-7 days. Serum levels of inhibin A, VEGF, TNFalpha, E2 and progesterone, the incidence of OHSS, ovarian size and pelvic fluid accumulation were evaluated.

RESULTS

Serum inhibin A, E2 and progesterone levels were significantly lower in the GnRH agonist group compared with the HCG group, particularly on the day of embryo transfer (P < 0.0001). Serum VEGF and TNFalpha levels were similar between the two groups. Four patients in the HCG group developed severe OHSS, whereas no patient had any symptoms or signs of OHSS in the GnRH-agonist group (P < 0.05).

CONCLUSIONS

In patients with PCO treated with FSH/GnRH antagonist, final oocyte maturation with GnRH agonist instead of HCG reduces significantly inhibin A, E2 and progesterone levels during the luteal phase. This phenomenon reflects the inhibition of the corpus luteum function and may explain, at least in part, the mechanism of OHSS prevention in high-risk patients. Our results do not support a crucial role for VEGF or TNFalpha in OHSS.

Functions of alpha 2 macroglobulins in pregnancy

The alpha 2 macroglobulins (A2M) are a family of abundant plasma proteins produced predominantly by the mammalian liver. Pregnancy zone proteins (PZP) of humans and rats are A2M family members that bind a wide variety of macromolecules including the important pregnancy-associated molecules such as vascular endothelial growth factor, placenta growth factor and glycodelin (also called PP14). Recently, a mouse gene analogous to PZP (A2M of pregnancy or A2Mp) was cloned. A2Mp has a unique pattern of expression in reproductive and cardiovascular tissues and, unexpectedly, is not expressed by liver. Since changes in heart function and remodeling of renal and uterine vasculature are amongst the earliest maternal responses to pregnancy, the product of the A2Mp gene has been postulated to systemically regulate these changes. A2Ms with and without non-covalently bound ligands also down regulate immune cell activation but promote immune cell migration, additional features associated with gestational success. Here, we review the A2M gene families of mice and humans, the predicted structural relationships between A2M and its pregnancy induced forms and the postulated roles for this gene family in normal pregnancy.

In vitro fertilization outcome in severe ovarian hyperstimulation syndrome: An age-matched contemporaneous control study

Aim:   Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening, iatrogenic complication of assisted reproduction and has been associated with poor in vitro fertilization outcome. The aim of the present study was to evaluate the pregnancy rate and outcome following severe OHSS, at a single center over a three-year period. Methods:   The incidence of severe OHSS at the IVF Center, National University of Singapore, in Singapore, was 4% (48 cases over 1200 cycles) during the period of 1997-2000. The present retrospective study compared 48 cases of severe OHSS to 144 age-matched, contemporaneous controls without OHSS. Results:   The total gonadotropin required for severe OHSS group was found to be lower than for that of controls (2664.06 ± 768.29 IU vs 3349.58 ± 2003.73 IU), although duration of stimulation was similar. The OHSS group was associated with a fivefold increase (OR 5.293, 95% CI: 2.116-13.238) in pregnancy rate compared to controls (87.5% vs 56.9%; P < 0.05). Late OHSS was more common (38/48 cases) and had a pregnancy rate of 97% per embryo transfer. There was no significant difference in the multiple pregnancy (54% vs 48%; P > 0.05) and miscarriage rates (14% vs 7.3%; P > 0.05) between the groups. Conclusion:   Severe OHSS at our center were mostly late onset. The pregnancy rate was significantly higher, but multiple pregnancy and miscarriage rates were not significantly increased when compared to the age-matched contemporaneous controls. (Reprod Med Biol 2005; 4: 207-211).

Characterization of a Murine Alpha 2 Macroglobulin Gene Expressed in Reproductive and Cardiovascular Tissue1

Full-length cDNA for a mouse gene A2-macroglobulin induced by pregnancy (A2mp) was cloned from mesometrial decidua at Gestation Day 10. The 4622-base pair cDNA encodes a protein of 1473 AA with >70% sequence identity and all typical domains of other A2M-family members in humans and rodents, despite unique absence of hepatic expression. The bait region is most distinct and has the greatest sequence similarity with rat acute-phase A2m. Northern blotting, reverse transcription and real-time-PCR, and in situ hybridization studies using C57Bl/6 mice revealed uterine induction of A2mp during decidualization and strong, midgestational association with modifying spiral arteries. Ovaries, testes, lactating mammary glands, heart, and kidney were the only additional organs with A2mp expression that was localized to granulosa and cumulus cells in secondary follicles; primary seminiferous epithelium, including Sertoli cells, mammary alveolar, and ductal epithelium; cardiac endothelium; and renal collecting tubules, respectively. Infusion of native human A2M into pregnant alymphoid or interferon-gamma gene-ablated mice overcame blocks to pregnancy-induced spiral artery modification in these strains. Activated human A2M was also effective, suggesting mechanisms independent of proteinase inhibition. Identification of cytokines, growth factors, or other molecules bound to A2MP should provide new insights into decidualization, spiral artery modification, and cardiovascular adaptation to pregnancy.

Early and late ovarian hyperstimulation syndrome: early pregnancy outcome and profile

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) in IVF/ICSI cycles may occur either as an early (early onset) or a late pattern (late onset). This observational study was designed to identify whether the onset pattern of OHSS is associated with the occurrence of pregnancy and the early pregnancy outcome.

METHODS

Among 4376 consecutive IVF/ICSI cycles, 113 patients were hospitalized for OHSS after IVF/ICSI treatment and were included in the study. The setting was the Dutch-speaking Brussels Free University Hospital, between June 2000 and September 2002.

RESULTS

Early OHSS occurred in 53 patients, and late OHSS complicated 60 patients. A total of 96.7% of the late OHSS cases occurred in a pregnancy cycle and were more likely to be severe than the early cases (P < 0.05). Although in the early group there initially was a 41.5% positive HCG rate per cycle, the clinical pregnancy rate fell to 28.3% as a result of a significantly (P < 0.05) increased preclinical pregnancy loss rate compared with the non-OHSS patients (31.8 versus 88.3%, respectively). The ongoing pregnancy rate per cycle was 14.4% in the early and 26.4% in the late group. Multiple pregnancy rates were high in both groups (40 and 45.5%, respectively), but only in the late group did the incidence reach significance compared with the non-OHSS population (45.5 versus 29.1%, P = 0.02). Estradiol levels and number of follicles on the day of HCG were significantly higher in the early OHSS group. However, there was no difference in estradiol values on the day of hospital admittance between the two groups. In addition, the number of follicles on the day of HCG administration appears to be a better prognostic indicator for the occurrence of severe OHSS than the estradiol values (87% of the severe cases had > or = 14 or follicles of a diameter > or = 11 mm, whereas only 50% of them had an estradiol value > or = 3000 ng/l).

CONCLUSIONS

The early OHSS pattern is associated with exogenously administered HCG and a higher risk of preclinical miscarriage, whereas late OHSS may be closely associated with the conception cycles, especially multiple pregnancies, and is more likely to be severe. Further clarification of these two different clinical entities could have implications for research protocols as well as for preventive and management strategies for OHSS.

New concepts in the understanding of the ovarian hyperstimulation syndrome

PURPOSE OF REVIEW

In this review we will evaluate the recent developments in the pathophysiology of the ovarian hyperstimulation syndrome, with special emphasis on mediators of human chorionic gonadotropin action.

RECENT FINDINGS

From all the different molecules investigated, it seems that vascular endothelial growth factor is the key mediator of human chorionic gonadotropin action on the vascular tree. Recent data show that although absolute serum vascular endothelial growth factor values are useless in predicting the occurrence of ovarian hyperstimulation syndrome, individual variations in binding profiles may account for clinical differences. It has been shown that vascular endothelial growth factor is produced, expressed and secreted in the ovary and that it mediates vascular permeability in response to human chorionic gonadotropin in a time-dependent fashion. This effect may be blocked by a synthetic compound (SU5416) developed to inhibit its high-affinity receptor, kinase domain containing receptor signaling in different cancers by avoiding the initial phosphorylation of vascular endothelial growth factor receptor-2.

SUMMARY

Vascular endothelial growth factor is a promising molecule in the understanding of ovarian hyperstimulation syndrome. Future treatments should be directed to modulate or inhibit its action on the vascular wall.

Administration of moderate and high doses of gonadotropins to female rats increases ovarian vascular endothelial growth factor (VEGF) and VEGF receptor-2 expression that is associated to vascular hyperpermeability

Convincing evidence supports the role of ovarian-origin vascular endothelial growth factor (VEGF) in inducing vascular permeability (VP) and ascites associated with ovarian hyperstimulation syndrome (OHSS) in mammals, including humans. A circulatory dysfunction has been described in every woman treated with gonadotropins for in vitro fertilization. It is not known, however, whether the action of gonadotropins also includes up-regulation of the VEGF receptor-2 (VEGFR-2) and whether increased VP is also found when milder stimulation is used. Thus, we applied an OHSS animal model to answer these questions. Immature female rats were stimulated with saline (control group) or with high (10 IU of eCG x 4 days + 30 IU hCG, OHSS group) or mild (10 IU of eCG + 10 IU of hCG, mild-stimulation group) doses of gonadotropins. The VP and the expression of whole-VEGF and VEGFR-2 mRNAs were analyzed through time-course experiments (0, 24, 48, and 96 h after hCG). Although eCG increased VP and the expression of VEGF and VEGFR-2 mRNAs in the ovaries of both mild- and OHSS-stimulated animals, hCG further augmented these parameters and produced the highest values after 48 h. A linear correlation was found between increased expression of VEGF and VEGFR-2 mRNAs and enhanced VP in both mild and OHSS groups. Immunohistochemistry showed the presence of VEGF and VEGFR-2 in the granulosa-lutein and endothelial cells of the entire corpus luteum. These studies confirm that in hyperstimulated animals as well as in mildly treated rats, VEGF and VEGFR-2 are overexpressed and associated with an increase in VP, which may be responsible for the accumulation of ascitic fluid in the syndrome.