A unique human chorionic gonadotropin antagonist suppresses ovarian hyperstimulation syndrome in rats

PKC-βII is downregulated in the premature ovarian failure SD rat model

We investigated the role of protein kinase c (PKC) -α and -β during the ovarian follicular dynamics using estrous cycle, gonadotropin-induced ovulation, and antral follicle culture, 4-vinylcyclohexene diepoxide (VCD)-induced premature ovarian failure (POF) in the SD rat models. We found the higher activity of PKC during the proestrus stage along with expression of PKC-α during the estrus and metestrus stages of the estrous cycle while PKC-β expression was increased during the diestrus, proestrus, and estrus stages. In response to pregnant mare gonadotropin (PMSG)-induced follicular recruitment and ovulation, the phosphorylated (Thr-642) PKC-β was increased. PKC activity inhibition by hispidin during the proestrus stage resulted in decreased antral follicles and corpus luteum. Treatment with hispidin resulted in the downregulation of granulosa cell (GC) biomarker, follicle stimulating hormone receptor (FSHR) expression in the cultured pre-antral follicle. During the forskolin-induced luteinization of human granulosa cells, the expression level of PKC-α and β (I and II) was decreased. In the POF condition, the activity of total PKC and the expression levels of PKC-α and β (I and II) were increased. Immunostaining depicted ubiquitous expression of PKC-α in the ovary during the estrous cycle and POF conditions. Taken together, we conclude the association of PKC-α and -β (I and II) during ovarian follicular dynamics where the expression level of PKC-α is increased, but the expression level of PKC-β (I and II) is suppressed in the POF condition in the SD rat model.

Gonadotropins and Their Analogs: Current and Potential Clinical Applications

The gonadotropin receptors LH receptor and FSH receptor play a central role in governing reproductive competency/fertility. Gonadotropin hormone analogs have been used clinically for decades in assisted reproductive therapies and in the treatment of various infertility disorders. Though these treatments are effective, the clinical protocols demand multiple injections, and the hormone preparations can lack uniformity and stability. The past two decades have seen a drive to develop chimeric and modified peptide analogs with more desirable pharmacokinetic profiles, with some displaying clinical efficacy, such as corifollitropin alfa, which is now in clinical use. More recently, low-molecular-weight, orally active molecules with activity at gonadotropin receptors have been developed. Some have excellent characteristics in animals and in human studies but have not reached the market-largely as a result of acquisitions by large pharma. Nonetheless, such molecules have the potential to mitigate risks currently associated with gonadotropin-based fertility treatments, such as ovarian hyperstimulation syndrome and the demands of injection-based therapies. There is also scope for novel use beyond the current remit of gonadotropin analogs in fertility treatments, including application as novel contraceptives; in the treatment of polycystic ovary syndrome; in the restoration of function to inactivating mutations of gonadotropin receptors; in the treatment of ovarian and prostate cancers; and in the prevention of bone loss and weight gain in postmenopausal women. Here we review the properties and clinical application of current gonadotropin preparations and their analogs, as well as the development of novel orally active, small-molecule nonpeptide analogs.

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.

Targeting angiogenesis in the pathological ovary

The ovary is a key tissue in the study of physiological neo-vascularisation in the adult and its study has highlighted important molecules involved in the regulation of angiogenesis in vivo. These include vascular endothelial growth factor, delta-like ligand 4, thrombospondin-1, prokineticin-1 and prostaglandin E2. Targeting these molecular pathways has therapeutic potential and their manipulation has an increasing preclinical and clinical role in the management of the pathological ovary. Targeting angiogenic pathways has utility in the promotion of ovarian angiogenesis to improve tissue and follicle survival and function as well as the prevention and management of ovarian hyperstimulation syndrome. There is a theoretical possibility that targeting angiogenesis may improve the function of the polycystic ovary and a real role for targeting angiogenesis in ovarian cancer.

Association between the luteinizing hormone/chorionic gonadotropin receptor (LHCGR) rs4073366 polymorphism and ovarian hyperstimulation syndrome during controlled ovarian hyperstimulation

BACKGROUND

The aim of this study was to determine the relationship between a purported luteinizing hormone/chorionic gonadotropin (LHCGR) high function polymorphism (rs4539842/insLQ) and outcome to controlled ovarian hyperstimulation (COH).

METHODS

This was a prospective study of 172 patients undergoing COH at the Fertility and IVF Center at GWU. DNA was isolated from blood samples and a region encompassing the insLQ polymorphism was sequenced. We also investigated a polymorphism (rs4073366 G > C) that was 142 bp from insLQ. The association of the insLQ and rs4073366 alleles and outcome to COH (number of mature follicles, estradiol level on day of human chorionic gonadotropin (hCG) administration, the number of eggs retrieved and ovarian hyperstimulation syndrome (OHSS)) was determined.

RESULTS

Increasing age and higher day 3 (basal) FSH levels were significantly associated with poorer response to COH. We found that both insLQ and rs4073366 were in linkage disequilibrium (LD) and no patients were homozygous for both recessive alleles (insLQ/insLQ; C/C). The insLQ variant was not significantly associated with any of the main outcomes to COH. Carrier status for the rs4073366 C variant was associated (P = 0.033) with an increased risk (OR 2.95, 95% CI = 1.09-7.96) of developing OHSS.

CONCLUSIONS

While age and day 3 FSH levels were predictive of outcome, we found no association between insLQ and patient response to COH. Interestingly, rs4073366 C variant carrier status was associated with OHSS risk. To the best of our knowledge, this is the first report suggesting that LHCGR genetic variation might function in patient risk for OHSS.

Human chorionic gonadotropin up-regulates expression of myeloid cell leukemia-1 protein in human granulosa-lutein cells: implication of corpus luteum rescue and ovarian hyperstimulation syndrome

CONTEXT

The corpus luteum is a dynamic endocrine structure with periodic development and regression during menstrual cycles. Its lifespan can be prolonged by human chorionic gonadotropin (hCG). However, the signal mechanisms of this phenomenon remain unclear.

OBJECTIVE

Our objective was to investigate the molecular mechanisms of hCG in the maintenance of the viability of granulosa-lutein cells.

DESIGN

Granulosa-lutein cells were obtained from women undergoing in vitro fertilization. We examined the effects of hCG on the survival of cultured granulosa-lutein cells. The signal pathway inducing antiapoptotic protein was investigated.

RESULTS

hCG enhanced viability of granulosa-lutein cells through antiapoptosis but not proliferation, because the apoptotic marker of annexin V was decreased, but the proliferative markers of Ki67 and proliferating cell nuclear antigen were not increased. Myeloid cell leukemia-1 (Mcl-1) protein, but not B-cell lymphoma protein-2 or B-cell lymphoma protein-xL, was significantly induced by hCG and LH. The granulosa-lutein cells secreted vascular endothelial growth factor that induced endothelial permeability. Mcl-1 small interfering RNA increased DNA fragmentation and diminished the antiapoptotic effect of hCG. hCG induced Mcl-1 expression through the LH/hCG receptor, adenylate cyclase, protein kinase A, and cAMP response element-binding protein signal pathway. Flavopiridol inhibited Mcl-1 production, released cytochrome c, and induced apoptosis of granulosa-lutein cells.

CONCLUSIONS

We first demonstrate that hCG prevents apoptosis of granulosa-lutein cells through the induction of Mcl-1 protein via the LH/hCG receptor and a cAMP response element-binding protein-dependent pathway. We may have found the molecular mechanism for luteal rescue during early pregnancy. Mcl-1 prevents apoptosis and increases cell viability but not proliferation as mechanisms for luteal rescue. Mcl-1 is a key molecule of hCG signaling.

Signal mechanisms of vascular endothelial growth factor and interleukin-8 in ovarian hyperstimulation syndrome: dopamine targets their common pathways

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is a serious complication of ovarian stimulation with massive ascites, pleural effusion and hemoconcentration. The pathophysiological signal mechanisms of OHSS are still unclear and merit further investigation.

METHODS

Various angiogenic cytokines of follicular fluid and ascites of patients with risk of OHSS were measured, and examined for inducing endothelial permeability. These include vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-8, basic fibroblast growth factor, tumor necrosis factor-alpha, IL-1alpha, IL-1beta and platelet-derived growth factor. We explore the molecular signal pathways of major contributing cytokines in granulosa-lutein cells and endothelial cells possibly involved in OHSS.

RESULTS

Neutralizing antibodies of VEGF or IL-8 significantly decreased follicular fluid- and ascites-induced endothelial permeability. Human chorionic gonadotrophin induced VEGF secretion of granulosa-lutein cells through the Sp1 and CREB dependent pathways. IL-8 activated CXCR1/2 of endothelial cells leading to VEGF receptor (VEGFR)-2 transactivation. Both VEGF and IL-8 of follicular fluid enhanced endothelial permeability via VEGFR-2-mediated Rho/Rock activation, actin polymerization and phosphorylations of VE-cadherin and occludin, resulting in opening of adherens junctions and tight junctions. Dopamine (2 microM) inhibited follicular fluid-induced VEGFR-2 signals and endothelial permeability, without diminishing migration and tube formation.

CONCLUSIONS

Our results suggest that VEGF and IL-8 secreted from corpora luteae may play major roles in OHSS. Delineation of signal pathways would be helpful for treatment. Dopamine may block VEGF- and IL-8-induced endothelial permeability by inhibiting common VEGFR-2 dependent signals.