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Differential regulation of VEGF after final oocyte maturation with GnRH agonist versus hCG: a rationale for OHSS reduction

2008; Elsevier BV; Volume: 91; Issue: 4 Linguagem: Inglês

10.1016/j.fertnstert.2008.08.118

1556-5653

Rosario Cerrillo Martín, Sara Rodríguez-Mora, Mercedes Mayoral, Alberto Pacheco, Javier Martínez‐Salazar, Juan A. García-Velasco,

Ovarian cancer diagnosis and treatment

In a prospective cohort study, we compared the effect of hCG and GnRH agonist triggering of final oocyte maturation on vascular endothelial growth factor production. Vascular endothelial growth factor follicular fluid concentration was significantly lower in response to GnRH agonist versus hCG, which may partially explain the absence of OHSS in these of women. In a prospective cohort study, we compared the effect of hCG and GnRH agonist triggering of final oocyte maturation on vascular endothelial growth factor production. Vascular endothelial growth factor follicular fluid concentration was significantly lower in response to GnRH agonist versus hCG, which may partially explain the absence of OHSS in these of women. Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of assisted reproductive treatments that are carried out with hCG to induce final oocyte maturation. The pathophysiologic mechanism that fully explains OHSS is still unknown, and therefore the majority of the therapeutic approaches to OHSS have been empirical. It occurs in 0.1%–4% of all the treatments that require controlled ovarian hyperstimulation (1Navot D. Bergh P.A. Laufer N. Ovarian hyperstimulation syndrome in novel reproductive technologies: prevention and treatment.Fertil Steril. 1992; 58: 249-261Abstract Full Text PDF PubMed Google Scholar). It has been demonstrated that after administration of hCG, the ovary releases different vasoactive substances that induce an increase in vascular permeability and fluid leakage to the third space, with ascites, and even hydrothorax and anasarca in severe cases, as the final consequence (2Balasch J. Fabregues F. Arroyo V. Peripheral arterial vasodilation hypothesis: a new insight into pathogenesis of ovarian hyperstimulation syndrome.Hum Reprod. 1998; 13: 2718-2730Crossref PubMed Scopus (56) Google Scholar). One of the key vasoactive substances released is vascular endothelial growth factor (VEGF) (3McClure N. Healy D.L. Rogers P.A. Sullivan J. Beaton L. Haning R.V. Vascular endothelial growth factor as capillary permeability agent in ovarian hyperstimulation syndrome.Lancet. 1994; 344: 235-236Abstract PubMed Scopus (342) Google Scholar, 4Abramov Y. Barak V. Nisman B. Schenker J.G. Vascular endothelial growth factor plasma levels correlate to the clinical picture in severe ovarian hyperstimulation syndrome.Fertil Steril. 1997; 68: 133-137Abstract Full Text PDF PubMed Scopus (29) Google Scholar). We (5Pellicer A. Albert C. Mercader A. Bonilla-Musoles F. Remohi J. Simon C. The pathogenesis of ovarian hyperstimulation syndrome: in vivo studies investigating the role of interleukin (IL)-1β, IL-6, and vascular endothelial growth factor (VEGF).Fertil Steril. 1999; 71: 482-489Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar, 6Gomez R. Simon C. Remohi J. Pellicer A. Vascular endothelial growth factor receptor-2 activation induces vascular permeability in hyperstimulated rats, and this effect is prevented by receptor blockade.Endocrinology. 2002; 143: 4339-4348Crossref PubMed Scopus (141) Google Scholar, 7Gomez R. Simon C. Remohi J. Pellicer A. Administration of moderate and high doses of gonadotropins to female rats incesaes ovarian vascular endomthelial growth factor (VEGF) ans VEGF receptor 1 expression that is asssociated to vascular hypermeability.Biol Reprod. 2003; 68: 2164-2171Crossref PubMed Scopus (89) Google Scholar, 8Villasante A. Pacheco A. Pau E. Ruiz A. Pellicer A. Garcia-Velasco J.A. Soluble vascular endothelial-cadherin levels correlate with clinical and biological aspects of severe ovarian hyperstimulation syndrome.Hum Reprod. 2008; 23: 662-667Crossref PubMed Scopus (30) Google Scholar) and others (9Soares S. Gomez R. Simon C. Garcia-Velasco J. Pellicer A. Targeting the vascular endothelial growth factor system to prevent ovarian hyperstimulation syndrome.Hum Reprod Update. 2008; 14: 321-333Crossref PubMed Scopus (159) Google Scholar) have shown that VEGF, among other proinflammatory cytokines, plays a fundamental role in the pathophysiology of OHSS. An attractive approach to avoid OHSS is to substitute hCG, which has a very long half-life, for another drug that may induce enough of an endogenous LH peak enough to induce final oocyte maturation. Gonadotropin-releasing hormone agonists have been successfully used in this way in egg donors, and not only are these agonists able to reduce the incidence of OHSS, but also the number of oocytes retrieved, egg quality, and implantation and pregnancy rates in egg recipients remain unaltered (10Acevedo B. Gómez-Palomares J.L. Ricciarelli M.D. Hernández E. Triggering ovulation with gonadotropin-releasing hormone agonist does not compromise embryo implantation rates.Fertil Steril. 2006; 86: 1682-1687Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar). However, the short half-life of the endogenous LH peak is not enough to have an adequate luteal phase. Most of the studies performed in patients showed reduced implantation and pregnancy rates, probably due to the insufficient luteal support by the short LH peak that exogenous progesterone alone was not enough to restore (12Griesenger G. Diedrich K. Devroey P. Kolibianakis E. GnRH agonist for triggering final oocyte maturation in the GnRH antagonist ovarian hyperstimulation protocol: a systematic review and meta-analysis.Hum Reprod Update. 2006; 12: 159-168Crossref PubMed Scopus (215) Google Scholar), although some groups have shown results similar to cycles where hCG was given (11Engmann L. Siano L. Schmidt D. Nulsen J. Maier D. Benadiva C. GnRH agonist to induce oocyte maturation during IVF in patients at high risk of OHSS.Reprod Biomed Online. 2006; 13: 639-644Abstract Full Text PDF PubMed Scopus (61) Google Scholar). Human corpus luteum produces many more biologically active products than just progesterone; therefore, further research is required on how to supplement luteal phase in these patients to optimize cycle outcome (13Kol S. Solt I. GnRH agonist for triggering final oocyte maturation in patients at risk of ovarian hyperstimulation syndrome: still a controversy?.J Assist Reprod Genet. 2008; 25: 63-66Crossref PubMed Scopus (27) Google Scholar). The aim of the present study was to investigate VEGF regulation in both serum and follicular fluid in patients undergoing IVF/intracytoplasmic sperm injection cycles comparing the effect of hCG to induce final oocyte maturation with that of a bolus of GnRH agonist. This was a prospective cohort study performed between October and December 2007 at a university-affiliated private infertility center. We included 39 oocyte donors undergoing standardized COH protocols for egg donation. All donors were included in our oocyte donation program after being thoroughly informed and having fulfilled our inclusion criteria. Subjects were aged between 18 and 35 years, and we had access to their complete medical history, which considered current or past exposure to radiation or hazardous chemical substances, IV drug use, and reproductive history. All subjects were shown to be normal in a physical and gynecologic examination, had no family history of hereditary or chromosomal diseases, had a normal karyotype, and tested negative in a screening for sexually transmitted diseases. An economic compensation stipulated by the Spanish government was given to the oocyte donor with the aim of mitigating the physical burden, job restrictions, and the number of times the donor had to come to the clinic during an ovarian stimulation cycle. Informed consent was given bey every patient before recruitment, and the trial was approved by the institutional ethical committee. Thirty-nine donors were recruited and allocated in a nonrandomized fashion to receive either hCG (group 1) or GnRH agonist (group 2) after COH. Donors in group 1 (n = 19) underwent COH according to our routine standard long protocol, as previously described (10Acevedo B. Gómez-Palomares J.L. Ricciarelli M.D. Hernández E. Triggering ovulation with gonadotropin-releasing hormone agonist does not compromise embryo implantation rates.Fertil Steril. 2006; 86: 1682-1687Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar), with 150 IU rFSH as starting dose. Donors in group 2 (n = 20) underwent COH with similar doses of gonadotropins as in our routine protocol, but when the leading follicle reached 14 mm, GnRH antagonist was started. When at least two follicles reached 18 mm in mean diameter, either 6,500 IU SC rhCG (Ovitrelle, Serono, Madrid, Spain) or a single bolus of 0.2 mg SC triptorelin (Decapeptyl; Ipsen Pharma, Madrid, Spain) was given and egg retrieval performed 36 h later. No luteal support was given. Plasma samples were obtained from all donors the day of hCG/GnRH agonist administration and the day of oocyte retrieval in tubes containing EDTA as anticoagulant. All plasma samples were centrifuged at 900g for 10 min at room temperature, and the cell-free supernatants were stored immediately in aliquots at −80°C until assayed. Follicular fluid from the first two mature follicles was aspirated into 10-mL tubes by transvaginal ultrasonographic-guided oocyte retrieval. The needle was withdrawn and completely emptied before each puncture, and no culture medium was used in the collection tubes. After removal of oocytes, follicular aspirates were centrifuged at 200g for 5 min, and supernatant was stored at −80'C until assayed. All samples were evaluated collectively by two investigators who were blinded to patient assignment. Concentrations of soluble VEGF165 in plasma and follicular fluid were determined with a commercially available ELISA kit (Quantikine; R&D Systems, Abingdon, UK) according to the manufacturer's instructions. The assay sensitivity was 5 pg/mL. The inter- and intra-assay coefficients of variation were <7% and < 4.5%, respectively. Categoric data were expressed as number and percentage, and numerical data as mean ± SEM. Student t test and χ2 test were used when appropriate. Significance was set at .05. All statistical analysis was performed with use of Sigmastat for Windows, version 2.0 (Jandel Scientific Corporation, San Rafael, CA). Relevant clinical data, basically body mass index (21.5 ± 2.9kg/m2 vs. 22.04 ± 2.3 kg/m2) and age (25.4 ± 4 yrs vs. 23.8 ± 3.9 yrs), from both groups of oocyte donors were similar. Both groups showed similar cycle outcomes in terms of duration of the stimulation (8.5 ± 1.1 vs. 8.9 ± 1.2 days; P=.29), total dose of rFSH (1,307 ± 235 IU vs. 1,377 ± 234 IU; P=.35), peak serum E2 (2,537 ± 1,032 vs. 2,095 ± 979 pg/mL; P=.17), serum P levels the day of hCG/GnRHa administration (0.8 ± 0.5 ng/mL vs. 0.8 ± 0.3 ng/mL; P=78), and oocytes retrieved (14 ± 4 vs. 17 ± 8; P=.12). We did find differences in the duration of the luteal phase: The period to menstrual onset in the non-hCG group was significantly shorter (10.2 ± 1.1 days vs. 5.2 ± 1.6 days; P<.001). Also, in the routine control we do to all our donors 1 week after the ovarian puncture, 42% of those who received hCG reported subjective complaints (mostly abdominal discomfort), whereas this percentage was 0% in those who received GnRH agonist to trigger ovulation. No OHSS was observed in either cohort. We did not find any differences in plasma levels of VEGF in either group, whether it was the day of hCG/GnRHa or the day of ovum pick-up (Table 1). However, a significant reduction in follicular fluid VEGF concentration was observed in those follicles coming from donors that received GnRHa instead of hCG (1,666 ± 53 [95% confidence interval (CI) 1,267–1,946] pg/mL vs. 1,207 ± 135 [95% CI 436–2,117] pg/mL; P<.001).Table 1Plasma and follicular fluid VEGF concentration (pg/mL).hCG n = 19GnRHa n = 20P valuePlasma, day of hCG or GnRHa158 ± 26 (44–326)173 ± 23 (63–314)NSPlasma, day of egg retrieval193 ± 28 (81–381)219 ± 27 (81–411)NSFollicular fluid1,666 ± 53 (1,267–1946)1,207 ± 135 (436–2,117)<.001Note: Values are presented as mean ± SEM (95% confidence interval). GnRH = GnRH agonist. Open table in a new tab Note: Values are presented as mean ± SEM (95% confidence interval). GnRH = GnRH agonist. To our knowledge, this is the first report investigating the differential secretion of a soluble vascular mediator (VEGF) when final oocyte maturation is induced by either hCG or a single bolus of GnRHa. The significantly lower concentrations of VEGF in the follicular fluid of patients who received GnRHa have direct clinical consequences to prevent OHSS. Vascular endothelial growth factor is the key molecule among the different vascular mediators released from the ovaries and other tissues in response to hCG (3McClure N. Healy D.L. Rogers P.A. Sullivan J. Beaton L. Haning R.V. Vascular endothelial growth factor as capillary permeability agent in ovarian hyperstimulation syndrome.Lancet. 1994; 344: 235-236Abstract PubMed Scopus (342) Google Scholar, 4Abramov Y. Barak V. Nisman B. Schenker J.G. Vascular endothelial growth factor plasma levels correlate to the clinical picture in severe ovarian hyperstimulation syndrome.Fertil Steril. 1997; 68: 133-137Abstract Full Text PDF PubMed Scopus (29) Google Scholar, 5Pellicer A. Albert C. Mercader A. Bonilla-Musoles F. Remohi J. Simon C. The pathogenesis of ovarian hyperstimulation syndrome: in vivo studies investigating the role of interleukin (IL)-1β, IL-6, and vascular endothelial growth factor (VEGF).Fertil Steril. 1999; 71: 482-489Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar, 6Gomez R. Simon C. Remohi J. Pellicer A. Vascular endothelial growth factor receptor-2 activation induces vascular permeability in hyperstimulated rats, and this effect is prevented by receptor blockade.Endocrinology. 2002; 143: 4339-4348Crossref PubMed Scopus (141) Google Scholar, 7Gomez R. Simon C. Remohi J. Pellicer A. Administration of moderate and high doses of gonadotropins to female rats incesaes ovarian vascular endomthelial growth factor (VEGF) ans VEGF receptor 1 expression that is asssociated to vascular hypermeability.Biol Reprod. 2003; 68: 2164-2171Crossref PubMed Scopus (89) Google Scholar, 9Soares S. Gomez R. Simon C. Garcia-Velasco J. Pellicer A. Targeting the vascular endothelial growth factor system to prevent ovarian hyperstimulation syndrome.Hum Reprod Update. 2008; 14: 321-333Crossref PubMed Scopus (159) Google Scholar). The long half-life of hCG of around 7 days, due to the continuous stimulus and liberation of vasoactive mediators, may complicate some assisted reproduction patients with OHSS, a potentially life-threatening consequence (13Kol S. Solt I. GnRH agonist for triggering final oocyte maturation in patients at risk of ovarian hyperstimulation syndrome: still a controversy?.J Assist Reprod Genet. 2008; 25: 63-66Crossref PubMed Scopus (27) Google Scholar). Therefore, the search for a surrogate for hCG has been crucial. Clinical empirical observations had previously confirmed that finding a surrogate for hCG that was able to induce final oocyte maturation was feasible and safe. For instance, exogenous LH could be an option, but impractical due to the high cost (13Kol S. Solt I. GnRH agonist for triggering final oocyte maturation in patients at risk of ovarian hyperstimulation syndrome: still a controversy?.J Assist Reprod Genet. 2008; 25: 63-66Crossref PubMed Scopus (27) Google Scholar). An alternative, in those patients undergoing COH with the antagonist—so the pituitary is not desensitized—is a bolus of GnRH agonist. Preliminary observations confirmed that the number of oocytes retrieved, fertilization, and embryo quality were unaffected (10Acevedo B. Gómez-Palomares J.L. Ricciarelli M.D. Hernández E. Triggering ovulation with gonadotropin-releasing hormone agonist does not compromise embryo implantation rates.Fertil Steril. 2006; 86: 1682-1687Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar). However, some controversy was raised, because implantation and pregnancy rates seemed to be diminished (11Engmann L. Siano L. Schmidt D. Nulsen J. Maier D. Benadiva C. GnRH agonist to induce oocyte maturation during IVF in patients at high risk of OHSS.Reprod Biomed Online. 2006; 13: 639-644Abstract Full Text PDF PubMed Scopus (61) Google Scholar, 12Griesenger G. Diedrich K. Devroey P. Kolibianakis E. GnRH agonist for triggering final oocyte maturation in the GnRH antagonist ovarian hyperstimulation protocol: a systematic review and meta-analysis.Hum Reprod Update. 2006; 12: 159-168Crossref PubMed Scopus (215) Google Scholar, 13Kol S. Solt I. GnRH agonist for triggering final oocyte maturation in patients at risk of ovarian hyperstimulation syndrome: still a controversy?.J Assist Reprod Genet. 2008; 25: 63-66Crossref PubMed Scopus (27) Google Scholar), although not all authors agreed (14Engman L. DiLuigi A. Schmidt D. Nulsen J. Maier D. Benadiva C. The use of gonadotropin-releasing hormone (GnRH) agonist to induce oocyte maturation after cotreatment with GnRH antagonist in high-risk patients undergoing in vitro fertilization prevents the risk of ovarian hyperstimulation syndrome: a prospective randomized controlled study.Fertil Steril. 2008; 89: 84-91Abstract Full Text Full Text PDF PubMed Scopus (345) Google Scholar). The fact that using this protocol in donors did not affect recipients' outcome clarified that the hypothetic reduction in cycle outcome was related to luteal support, an area that needs further research. Previous research by Babayof et al. (15Babayof R. Margalioth E. Huleihel M. Amash A. Zylber-Haran E. Gal M. et al.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.Hum Reprod. 2006; 21: 1260-1265Crossref PubMed Scopus (142) Google Scholar) regarding VEGF differential regulation by hCG or GnRH agonist did not find significant differences in serum. The facts that VEGF was measured only in serum—and not in plasma—and that follicular fluid VEGF concentrations were not evaluated could explain their findings. Because VEGF is secreted by granulosa cells, the ideal biologic sample to evaluate it would be follicular fluid, and indeed, differences were significant. A limitation of the present work is that we used two different protocols (standard long and antagonist) in our donors. However, this should not be a major drawback, because similar concentrations of VEGF have been found in serum and follicular fluid of women undergoing these two protocols (16Asimakopoulos B. Köster F. Felberbaum R. Al-Hasani S. Diedrich K. Nikolettos N. Cytokine and hormonal profile in blood serum and follicular fluids during ovarian stimulation with the multidose antagonist or the long agonist protocol.Hum Reprod. 2006; 21: 3091-3095Crossref PubMed Scopus (20) Google Scholar). Obviously, owing to the limited sample size, we cannot exclude other causes apart from the reduced follicular fluid VEGF concentration that may contribute to the absence of OHSS in this series. To conclude, we have demonstrated that intrafollicular VEGF concentration is reduced when final oocyte maturation is induced by a single bolus of GnRH agonist instead of hCG, which may cause luteolysis and thus contribute to reducing the incidence of OHSS. This observation, together with a shorter duration of the luteal phase, a minimal discomfort for the donor, and the previous evidence that oocyte/embryo quality is not affected, should help us to implement this approach as the routine standard protocol in oocyte donors.