Elevated levels of interleukin-2, soluble interleukin-2 receptor alpha, interleukin-6, soluble interleukin-6 receptor and vascular endothelial growth factor in serum and ascitic fluid of patients with severe ovarian hyperstimulation syndrome

The Interleukin-6 trans-signaling promotes progesterone production in human granulosa-lutein cells

As a critical paracrine regulator of multiple reproductive functions, the cytokine interleukin-6 (IL-6) is expressed in human granulosa cells and can be detected in follicular fluid. At present, the functional role of IL-6 in the regulation of ovarian steroidogenesis is controversial. Moreover, the detailed molecular mechanisms by which IL-6 regulates the production of progesterone in human granulosa cells remain to be elucidated. In the present study, we used primary and immortalized human granulosa-lutein (hGL) cells to investigate the effects of IL-6 on progesterone synthesis and the underlying molecular mechanisms. We found that IL-6 trans-signaling by the combined addition of IL-6 and soluble IL-6 receptor (sIL-6Rα) induced StAR expression and progesterone production in hGL cells. Additionally, IL-6/sIL-6Rα activated the phosphorylation of Janus activated kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3), and the cellular effects were abolished by AG490 (JAK2 inhibitor), C188–9 (STAT3 inhibitor), or siRNA-mediated knockdown of STAT3. IL-6 trans-signaling-induced activation of JAK2/STAT3 also upregulated the expression of suppressor of cytokine signaling 3 (SOCS3), which, in turn, negatively regulated the JAK2/STAT3 pathway by suppressing STAT3 activation and its downstream effects. Our findings provide insight into the molecular mechanisms by which IL-6 trans-signaling modulates steroidogenesis in hGL cells.

Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells

The expression of tyrosine kinase with immunoglobulin-like and epidermal growth factor-like domains 1 (Tie1), a transmembrane protein expressed almost exclusively by endothelial cells, has been reported in granulosa cells. However, its significance in ovarian hyperstimulation syndrome (OHSS), which can occur after the injection of gonadotropins in infertile women undergoing controlled ovarian stimulation, is unknown. Here, we report significantly increased Tie1 and vascular endothelial growth factor (VEGF) expression in cultured granulosa cells from OHSS patients, as well as ovaries from rats with experimentally established OHSS, compared to controls, with the levels of both proteins also increasing in granulosa and SVOG cells (a nontumorigenic human granulosa-lutein cell line) treated with an acute dose of human chorionic gonadotropin (hCG). Tie1 silencing abolished the hCG-induced VEGF level in SVOG cells and attenuated the progression of OHSS in rats, as determined by histological analysis. Further studies in SVOG cells revealed that the hCG-induced upregulation of Tie1 expression involved the phosphoinositide 3-kinase/protein kinase B signaling pathway. We also report that early growth response protein 1 (EGR1), whose expression was also upregulated by hCG, bound directly to the Tie1 promoter and activated its transcription. Taken together, our results indicate that Tie1 may be a therapeutic target in cases of moderate-to-severe OHSS. Further studies are needed to address its clinical relevance.

The IL6/sIL-6Rα trans-signaling increases PGE2 production in human granulosa cells

As a potent autocrine regulator, the proinflammatory cytokine interleukin 6 (IL6) is expressed in granulosa cells and follicular fluid and is involved in the modulation of various follicular functions, including follicular development and ovulation. At present, the detailed molecular mechanisms by which IL6 regulates the event of ovulation remain to be elucidated. In the present study, primary and immortalized (SVOG) human granulosa-lutein (hGL) cells were used to investigate the effects of IL6 on the expression of prostaglandin-endoperoxide synthase 2 (PTGS2) and the subsequent synthesis of prostaglandin E2 (PGE2) and to investigate the underlying molecular mechanisms. We found that instead of classic signaling, IL6/sIL-6Rα trans-signaling induced the expression of PTGS2 and production of PGE2 in both SVOG cells and primary hGL cells. Moreover, IL6/sIL-6Rα activated the phosphorylation of Janus activated kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3), which in turn induced STAT3 nuclear translocation. Additionally, these effects were suppressed by the addition of inhibitors (AG490 for JAK2 and C188-9 for STAT3) and by the siRNA-mediated knockdown of STAT3. Additionally, suppressor of cytokine signaling 3 (SOCS3) acts as a negative-feedback regulator in IL6/sIL-6Rα-induced cellular activities, including the activation and nuclear translocation of STAT3, upregulation of PTGS2 expression, and increase in PGE2 production in SVOG cells. In conclusion, IL6 trans-signaling upregulates the expression of PTGS2 and increases the production of PGE2 via the JAK2/STAT3/SOCS3 signaling pathway in hGL cells. Our findings provide insights into the molecular mechanisms by which IL6 trans-signaling may potentially modulate the event of ovulation in human ovaries.

Effect of GnRH-antagonist, mifepristone and letrozole on preventing ovarian hyperstimulation syndrome in rat model

RESEARCH QUESTION

Can luteolysis-targeted drugs, gonadotrophin-releasing hormone antagonist (GnRH-ant), mifepristone and letrozole, administered separately or in combination, prevent the progression of ovarian hyperstimulation syndrome (OHSS) in a rat model?

DESIGN

Thirty-six female Wistar rats were randomly divided into six groups, including control group (OHSS group, ovarian hyperstimulation-induced OHSS); GnRH-ant group (OHSS with GnRH-ant treatment); mifepristone group (OHSS with mifepristone treatment); letrozole group (OHSS with letrozole treatment); combination group (OHSS with GnRH-ant, mifepristone and letrozole treatment in combination). The main outcomes were the alterations in OHSS-related indices, including ovarian weight, vascular permeability, serum oestradiol and progesterone levels, corpus luteum proportion and diameter, ovarian vascular endothelial growth factor (VEGF), interleukin 6 (IL-6), caspase-3 and cleaved caspase-3 levels.

RESULTS

No significant difference was found in body weight gain among the six groups. Compared with the control group, the OHSS group showed significant increases in all OHSS-related indices. GnRH-ant treatment showed decreases in vascular permeability, serum oestradiol level, corpus luteum diameter, ovarian VEGF /IL-6 mRNA levels, and increases in ovarian caspase-3 and cleaved caspase-3 levels. Mifepristone treatment demonstrated reduction in serum progesterone level and corpus luteum diameter, and elevation in ovarian caspase-3 and cleaved caspase-3 levels. Letrozole treatment displayed a decline in serum oestradiol level and corpus luteum diameter, and up-regulation in ovarian caspase-3 and cleaved caspase-3 levels. The combination treatment by GnRH-ant, mifepristone and letrozole showed enhanced synergistic effect on reducing OHSS-related indices.

CONCLUSIONS

GnRH-ant, mifepristone and letrozole are beneficial in preventing the progression of OHSS through different luteolytic mechanisms. Cocktail style treatment shows enhanced synergistic effect on preventing the progression of OHSS.

Comparative analysis of abdominal fluid cytokine levels in ovarian hyperstimulation syndrome (OHSS)

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is a rare, yet severe, iatrogenic complication of ovulation induction therapy during assisted reproductive procedures. Our group previously detected atypical cells in the ascitic fluid of OHSS patients, although no malignancy developed during follow up. Here, the aim was to perform a comparative analysis of the cytokines present in the abdominal fluid of patients affected by OHSS versus patients with advanced ovarian cancer, a benign adnexal mass, or ovarian endometriosis.

METHODS

This prospective, non-randomized study was conducted at the Clinical Center of the University of Pecs Department of Obstetrics and Gynecology/Reproductive Center between October 2016 and March 2018. Abdominal fluid samples were obtained from 76 patients and subjected to Luminex analysis. The samples were collected from patients with OHSS (OHSS; n = 16), advanced ovarian cancer (OC; n = 22), a benign adnexal mass (BAM; n = 21), or ovarian endometriosis (EM; n = 17). Data were subjected to the non-parametric Kruskal-Wallis test and Spearman's rank correlation coefficient to identify statistical differences between the four study groups.

RESULTS

Leukocytosis and hemoconcentration were detected in the peripheral blood of OHSS patients. Abdominal fluid analysis further revealed significantly higher levels of interleukin (IL)-6, IL-8, IL-10, and transforming growth factor (TGF)-β in both the OHSS and OC groups compared to the BAM and EM groups. The highest concentration of vascular endothelial growth factor (VEGF) was detected in the OC group, while a significantly lower level was detected in the OHSS group. Moreover, VEGF levels in OC and OHSS groups were significantly elevated compared to the levels in the BAM and EM groups.

CONCLUSIONS

Vasoactive and hematogenic cytokines were present at higher levels in both the OHSS and OC abdominal fluid samples compared to the fluid samples obtained from the peritoneal cavity of the BAM patients. It is possible that these cytokines play an important role in the formation of ascites.

Revisiting ovarian hyper stimulation syndrome: Towards OHSS free clinic

A rapid development and application of assisted reproductive technologies (ARTs) and ovulation-induction drugs may lead to ovarian hyper stimulation syndrome (OHSS). Young age, low body mass index (BMI), polycystic ovarian syndrome (PCOS), previous OHSS, high follicle count, and elevated serum estradiol (E2) are the certain factors that predispose women to OHSS. Many strategies have been used to reduce or avoid OHSS. Use of human chorionic gonadotropin (hCG) increases ovarian vascular permeability and is responsible for activating the vascular endothelial growth factors (VEGF) pathway and thus the entire cascade, leading to symptomatic OHSS. Gonadotropin-releasing hormone (GnRH) agonists are used as a replacement for hCG for final oocyte maturation in antagonist cycles. Reducing or eliminating the use of hCG and use of GnRH agonist triggered GnRH antagonist cycles and cryopreservation of oocytes or embryos is the most promising approach in making OHSS free clinic a reality.

Prevention of ovarian hyperstimulation syndrome in a rat model: comparison of the efficacy of tocilizumab with that of ranibizumab, cabergoline, and a gonadotropin-releasing hormone antagonist

The aim of the study is to investigate the effects of the interleukin-6 (IL-6) blocker tocilizumab in a hyperstimulated rat model and compare it with ranibizumab, a gonadotropin-releasing hormone antagonist (GnRHA), and cabergoline. Forty-seven rats were randomly divided into the following seven groups: Group 1: OHS; Group 2: OHS+ GnRHA; Group 3: OHS + ranibizumab; Group 4: OHS + cabergoline; Group 5: OHS + low-dose tocilizumab (TL); Group 6: OHS + high-dose tocilizumab (TH); Group 7: sham. Ovarian weight was significantly lower only in the ranibizumab group than in the OHS group. Estrogen levels were significantly lower in the GnRHA group than in the OHS and the treatment groups. Progesterone levels were significantly lower in the ranibizumab, cabergoline, and TL groups than in the OHS group. Among the treatment groups, corpus luteum counts were lower than in the OHS group. Corpus luteum counts were lowest in the tocilizumab groups. IL-6 intensity was lower in all treatment groups than in the OHS group. In the ranibizumab group IL-6 intensity was the lowest. The TL group did not significantly differ from the GnRHA and cabergoline groups regarding IL-6 expression. Ovarian VEGF expression was significantly lower in all treatment groups. For the TL, ranibizumab, and cabergoline groups VEGF intensity was similar. Tocilizumab may be a new strategy for preventing ovarian hyperstimulation syndrome by inhibition of IL-6.

Apolipoprotein A1 as a potential biomarker in the ascitic fluid for the differentiation of advanced ovarian cancers

CONTEXT

Primary ovarian cancer and ovarian metastasis from non-ovarian cancers in advanced stage are closely mimicking conditions whose therapeutics and prognosis are different.

OBJECTIVE

To identify biomarkers that can differentiate the two variants of advanced ovarian cancers.

METHODS

Gel-based proteomics and antibody-based assays were used to study the differentially expressed proteins in the ascitic fluid of fourteen patients with advanced ovarian cancers.

RESULTS

Programmed Cell Death 1-Ligand 2, apolipoprotein A1, apolipoprotein A4 and anti-human fas antibody are differentially expressed proteins.

CONCLUSIONS

Apolipoprotein A1 with a 61.8 ng/ml cut-off is a potential biomarker with the best differentiating statistical parameters.

The role of IL-6 trans-signaling in vascular leakage: implications for ovarian hyperstimulation syndrome in a murine model

CONTEXT

The inflammatory cytokine IL-6 is related to ovarian hyperstimulation syndrome (OHSS), although the functional role of IL-6 in OHSS remains largely unknown.

OBJECTIVE

A key feature of the IL-6 response is that its regulation is dependent on IL-6 trans-signaling via soluble IL-6 receptor-α (sIL-6Rα). The objective of the study was to elucidate the mechanistic role of IL-6 trans-signaling in the vascular leakage that underlies the pathophysiology of OHSS.

DESIGN

Ovarian endothelial cells (ECs) and granulosa-lutein cells were obtained from women undergoing in vitro fertilization. OHSS was induced in mice by administering gonadotropins for 2 days followed by human chorionic gonadotropin. The functional role of IL-6 trans-signaling in OHSS was verified using the designer cytokines Hyper IL-6 and sgp130-Fc.

RESULTS

The follicular fluid levels of sIL-6Rα were elevated in women at high risk for OHSS. In the murine OHSS model, stimulation with gonadotropins significantly induces ovarian IL-6 and sIL-6Rα expression. In vitro, FSH induces de novo sIL-6Rα synthesis in granulosa-lutein cells through a protein kinase C-dependent pathway. In addition, sIL-6Rα was released by leukocytes in the presence of conditioned medium from human chorionic gonadotropin-treated granulosa-lutein cells. Ovarian ECs responded to the IL-6Rα-IL-6 complex (Hyper IL-6) but not to IL-6 alone. With activation of signal transducer and activator of transcription 3 (STAT3) and ERK, Hyper IL-6 increased vascular endothelial growth factor expression and the vascular permeability of ECs. Selective blockade of IL-6 trans-signaling by sgp130-Fc significantly inhibited vascular endothelial growth factor expression and prevented OHSS in mice.

CONCLUSIONS

IL-6 trans-signaling is activated during the ovarian stimulation process. Our findings provide insight into the biologic effects of IL-6 trans-signaling in OHSS and highlight that IL-6 trans-signaling can induce vascular leakage in this disease.

LIF and sIL-2R plasma concentrations in IVF patients on the day of embryo transfer: predictive markers of IVF outcome

Successful implantation is still the limiting step in IVF. We hypothesized that maternal plasma concentrations of certain cytokines at the time of embryo transfer could predict the likelihood of successful implantation and pregnancy. sIL-2R, IL-6, LIF, and MMP2 concentrations were measured in plasma from 160 IVF patients (natural and stimulated IVF cycles) on the morning of the embryo transfer (ET0) and 14 days later (ET+14). Patients were ultimately subdivided into four groups depending on the IVF treatment outcome (pregnancy failure, biochemical pregnancy, first-trimester miscarriage and normal term delivery). In natural and stimulated IVF cycles at ET0, sIL-2R concentrations were threefold higher in biochemical pregnancies than in pregnancy failures (P=0.020), and in natural cycles only, 2.5-fold higher in normal term deliveries than in pregnancy failures (P=0.023). Conversely, in natural and stimulated IVF cycles at ET0, LIF concentrations were one third lower in biochemical pregnancies/first-trimester miscarriages compared with pregnancy failures (P=0.042). We suggest that high sIL-2R and low LIF concentrations in maternal plasma on the morning of the embryo transfer might be associated with increased risks of early pregnancy loss, while a basal level of sIL-2R is necessary for normal term delivery outcome. Both cytokine measurements might therefore be useful in the management of IVF patients, and modulation of their concentrations could be investigated as a therapeutic alternative for women with abnormal concentrations at the time of embryo transfer.

Vascular endothelial growth factor production by circulating immune cells is elevated in ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic disease manifesting itself by ovarian enlargement and massive ascites with increased peritoneal capillary permeability. Although vascular endothelial growth factor (VEGF) is considered to play the main role in developing OHSS, its precise mechanism remains unclear. In this study, we examined possible roles of circulating immune cells in the pathogenesis of OHSS.

METHODS

Peripheral blood mononuclear cells (PBMC) and plasma were collected from healthy non-pregnant volunteers and from patients receiving ovulation induction for IVF. PBMC were cultured for 48 h. Plasma and/or medium concentrations of VEGF, estradiol and progesterone were measured using enzyme-linked immunosorbent assay and radioimmunoassay kits.

RESULTS

VEGF production by cultured PBMC and plasma concentrations of VEGF taken from patients with early onset OHSS (n = 12) were significantly higher than those in non-pregnant volunteers and patients without OHSS whose oocyte retrieval rates were similar to that of OHSS patients. OHSS patients were further classified into a high plasma VEGF concentration group and a high culture medium VEGF group. There was no significant correlation among VEGF production by PBMC and plasma concentration of VEGF, estradiol or progesterone.

CONCLUSION

Although mechanistic evidence has not been provided, our study does provide new evidence to suggest that circulating immune cells are involved in the pathogenesis of OHSS via VEGF production.

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.

VEGF: an update on biological and therapeutic aspects

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen and an angiogenic inducer as well as a mediator of vascular permeability. VEGF is essential for developmental angiogenesis and is also required for female reproductive functions and endochondral bone formation. Substantial evidence also implicates VEGF in tumors and intraocular neovascular syndromes. Currently, several clinical trials are ongoing to test the hypothesis that the inhibition of VEGF activity may be beneficial for these conditions.

An autopsy case of ovarian hyperstimulation syndrome with massive pulmonary edema and pleural effusion

Ovarian hyperstimulation syndrome (OHSS) is the most serious complication of ovulation induction with exogenous gonadotropins, such as human menopausal gonadotropin and follicle-stimulating hormone. These hormones are considered to increase capillary permeability and cause third space fluid shift. We report an autopsy case of severe OHSS in a 28-year-old Japanese female. The patient developed bilateral chest pain and progressive dyspnea during the course of administration of human gonadotropins. Pleural effusion and hypouresis clinically disappeared 4 days after the onset of the symptoms, but the patient died suddenly of rapid respiratory insufficiency. Autopsy examination revealed massive pulmonary edema, intra-alveolar hemorrhage and pleural effusion without any evidence of pulmonary thromboembolism. Histopathological examination of the ovary demonstrated multiple well-developed follicle formations, consistent with OHSS. It is very important to recognize that massive pulmonary edema can occur in a patient with OHSS. To the best of our knowledge, this is the first autopsy report of a patient with severe OHSS.