Deficiency of C1QL1 Reduced Murine Ovarian Follicle Reserve Through Intraovarian and Endocrine Control

Ovarian aging is associated with depletion of the ovarian follicle reserve, which is the key determinant of fertility potential in females. In this study, we found that the small, secreted protein complement 1Q-like (C1QL1) is involved in the regulation of follicle depletion through intraovarian and endocrine control in a multidimensional collaborative manner. C1ql1 was detected to be conserved in the ovary and showed high transcript levels during folliculogenesis. Blockade of C1QL1 by IP and ovarian intrabursal injection of C1QL1 antiserum into prepubertal mice impaired folliculogenesis accompanied by reductions in body weight, fat mass, and intraovarian lipid accumulation. An elevation of circulating estradiol levels, reduction of hypothalamic KISS1 and GnRH expression, and a decrease in serum FSH levels were found in C1QL1-deficient mice. In C1QL1-deficient ovaries, many primordial follicles were recruited and developed into medium follicles but underwent atresia at the large follicle stages, which resulted in depletion of follicle reserve. Depletion of C1QL1 alleviated the inhibitory effect of C1QL1 on granulosa cell apoptosis and the stimulatory effect of C1QL1 on granulosa cell autophagy, which resulted in accumulation in the preantral and early antral follicles and an increase in the atretic follicles. The abnormal profile of endocrine hormones accelerated the intraovarian effect of C1QL1 deficiency and further led to depletion of ovarian reserve. Altogether, this study revealed the expression patterns and the mechanism of action of C1QL1 during folliculogenesis and demonstrated that deficiency of C1QL1 caused ovarian follicular depletion.

Deficiency of C1QL1 reduced murine ovarian follicle reserve through intraovarian and endocrine control

Ovarian aging is associated with depletion of the ovarian follicle reserve, which is the key determinant of fertility potential in females. In this study, we found that the small secreted protein C1QL1 is involved in the regulation of follicle depletion through intraovarian and endocrine control in a multidimensional collaborative manner. C1ql1 was detected to be conserved in the ovary and showed high transcript levels during folliculogenesis. Blockade of C1QL1 by intraperitoneal and ovarian intrabursal injection of C1QL1 antiserum into prepubertal mice impaired folliculogenesis accompanied by reductions in body weight, fat mass and intraovarian lipid accumulation. An elevation of circulating estradiol levels, reduction of hypothalamic KISS1 and GnRH expression and a decrease in serum FSH levels were found in C1QL1-deficient mice. In C1QL1-deficient ovaries, a large number of primordial follicles were recruited and developed into medium follicles, but underwent atresia at the large follicle stages, which resulted in depletion of follicle reserve. Depletion of C1QL1 alleviated the inhibitory effect of C1QL1 on granulosa cell apoptosis and the stimulatory effect of C1QL1 on granulosa cell autophagy, which resulted in accumulation in the preantral and early antral follicles and an increase in the atretic follicles. The abnormal profile of endocrine hormones accelerated the intraovarian effect of C1QL1 deficiency and further led to depletion of ovarian reserve. Altogether, this study revealed the expression patterns and the mechanism of action of C1QL1 during folliculogenesis, and demonstrated that deficiency of C1QL1 caused ovarian follicular depletion.

Germ-Somatic Cell Interactions Are Involved in Establishing the Follicle Reserve in Mammals

Mammalian females are born with a finite reserve of ovarian follicles, the functional units of the ovary. Building an ovarian follicle involves a complex interaction between multiple cell types, of which the oocyte germ cell and the somatic granulosa cells play a major role. Germ–somatic cell interactions are modulated by factors of different cell origins that influence ovarian development. In early development, failure in correct germ–somatic cell communication can cause abnormalities in ovarian development. These abnormalities can lead to deficient oocyte differentiation, to a diminished ovarian follicle reserve, and consequently to early loss of fertility. However, oocyte–granulosa cell communication is also extremely important for the acquisition of oocyte competence until ovulation. In this paper, we will visit the establishment of follicle reserve, with particular emphasis in germ–somatic cell interactions, and their importance for human fertility.

GnRH agonist leuprolide acetate does not confer any protection against ovarian damage induced by chemotherapy and radiation in vitro

STUDY QUESTION

Is there any in vitro evidence for or against ovarian protection by co-administration of a GnRH agonist with chemotherapy in human?

SUMMARY ANSWER

The co-administration of GnRH agonist leuprolide acetate with cytotoxic chemotherapy agents does not preserve ovarian reserve in vitro.

WHAT IS KNOWN ALREADY

Randomized controlled trials of the co-administration of gonadotrophin-releasing hormone (GnRH) agonists with adjuvant chemotherapy to preserve ovarian function have shown contradictory results. This fact, together with the lack of a proven molecular mechanism of action for ovarian protection with GnRH agonist (GnRHa) places this approach as a fertility preservation strategy under scrutiny. We therefore aimed in this study to provide in vitro evidence for or against the role of GnRHa in the prevention of chemotherapy-induced damage in human ovary.

STUDY DESIGN, SETTINGS, SIZE AND DURATION

This translational research study of ex vivo and in vitro models of human ovary and granulosa cells was conducted in a university hospital between 2013 and 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovarian cortical pieces (n = 15, age 14-37) and mitotic non-luteinized (COV434 and HGrC1) and non-mitotic luteinized human granulosa cells (HLGC) expressing GnRH receptor were used for the experiments. The samples were treated with cyclophosphamide, cisplatin, paclitaxel, 5-FU, or TAC combination regimen (docetaxel, adriamycin and cyclophosphamide) with and without GnRHa leuprolide acetate for 24 h. DNA damage, apoptosis, follicle reserve, hormone markers of ovarian function and reserve (estradiol (E2), progesterone (P) and anti-mullerian hormone (AMH)) and the expression of anti-apoptotic genes (bcl-2, bcl-xL, bcl-2L2, Mcl-1, BIRC-2 and XIAP) were compared among control, chemotherapy and chemotherapy + GnRHa groups.

MAIN RESULTS AND THE ROLE OF CHANCE

The greatest magnitude of cytotoxicity was observed in the samples treated with cyclophosphamide, cisplatin and TAC regimen. Exposure to these drugs resulted in DNA damage, apoptosis and massive follicle loss along with a concurrent decline in the steroidogenic activity of the samples. GnRHa co-administered with chemotherapy agents stimulated its receptors and raised intracellular cAMP levels. But it neither activated anti-apoptotic pathways nor prevented follicle loss, DNA damage and apoptosis induced by these drugs.

LIMITATIONS, REASONS FOR CAUTION

Our findings do not conclusively rule out the possibility that GnRHa may offer protection, if any, through some other mechanisms in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

GnRH agonist treatment with chemotherapy does not prevent or ameliorate ovarian damage and follicle loss in vitro. These data can be useful when consulting a young patient who may wish to receive GnRH treatment with chemotherapy to protect her ovaries from chemotherapy-induced damage.

Early stage management of ovarian endometrioma to prevent infertility

There are now convincing data showing that cystectomy of the endometrioma is not only no cure of infertility, but may harm follicle reserve. The question arises why is cystectomy for an endometrioma, in contrast with other -benign cysts, a risk for follicle reserve and how can ovarian damage be prevented. Surgical specimens of ovaries with endometrioma in situ show in the majority of cases manifestly a combined -extra-ovarian and intra-ovarian pathology with the cortex invaginated to form a pseudocyst. The extra-ovarian pathology includes endometrial lining of the cortex, bleeding and adhesions with surrounding tissues. The intra-ovarian pathology is characterized by microscopic stromal implants, fibrosis, smooth muscle metaplasia and -arteriosclerosis, all affecting follicle reserve in the endometrioma bed. Clinically, ovarioscopy allows differential diagnosis (e.g. luteal cyst) and evaluation of the degree of fibrosis and darkening of the cortical wall. Transvaginal colour Doppler sonography can demonstrate the presence and extent of devascularisation in the endometrioma bed. Given this reality, surgery should be based on evaluation of the pathology of the endometrioma bed, but not on the mere size of the chocolate cyst. The main clinical problem is indeed the delayed diagnosis and consequently advanced irreversible cortical damage. Therefore, the sooner endometriomas are diagnosed, the better, because it increases the chances that vascularisation of the endometrioma bed is preserved. Finally, ablation, but not excision is the treatment of choice. The diagnosis of endometriosis is traditionally based on laparoscopy, but in a sexually active adolescent transvaginal endoscopy can be proposed.