Study On The Role Of Dysregulated IL-11/IL-11 Rreceptors In The Pathogenesis Of Premature Ovarian Insufficiency

Objective:Premature ovarian insufficiency(POI)is characterized by hypergonadotropic amenorrhea and hypoestrogenism in women under 40 years of age,which occurs in about 1%of female population.Women with POI present infrequent or absent periods,infertility and menopausal symptoms.In addition,they had long-term adverse effects of estrogen deprivation,such as,osteoporosis and cardiovascular diseases.The number of oocytes in the human ovaries is determined during fetal life and progressively decreases throughout the female reproductive life span.POI is pathophysiologically complicated and etiologically heterogeneous.Any molecular mechanisms involved in diminishing primordial follicle pool or accelerating premature follicle depletion will cause POI,such as genetic factors,iatrogenic injuries,infection and autoimmune dysfunctions.As a major cause of infertility,POI represents one of the most challenging issues in female reproduction.Upon confirmed diagnosis,available ovarian function seldom exists.Additionally,there is no effective strategy to improve or rescue ovarian function and fertility currently.Therefore,it is of great importance to identify risk factors of ovarian insufficiency.Of all the underlying aetiologies,autoimmunity is responsible for approximately 4-30%of POI cases.No specific,reliable,and non-invasive diagnostic tests for autoimmune POI exist currently.How autoimmunity induces ovarian senescence has not been fully established.The cytokine interleukin-11(IL-11),a multifunctional protein with diverse roles in the normal cell signaling and in various pathologies,is produced by fibroblasts,keratinocytes,and endothelial cells as well as immune cells such as lymphocytes,monocytes,and macrophages.It belongs to the IL-6 cytokine family which share the common signaling receptor subunit glycoprotein 130kDa(gp130).Signaling by IL-11 proceeds via an interaction of the protein with its membrane-specific receptor IL-11R and a subsequent interaction of the complex with the transmembrane signal-transducing receptor GP130 and activates the Janus kinase(JAK)/Signal transducers and activators of transcription(STAT)pathway.IL-11 has been implicated in various functions including B-cell stimulation,regulation of cell cycle,metabolic and neurotrophic function.As an anti-inflammatory factor,IL-11 acts through specific cytokine inhibitors and receptors to regulate human immune response.Dysregulation of IL-11/IL-11 receptors has been reported to be involved in many diseases,such as cancers,inflammatory autoimmune disorders and infertility.Besides,IL-11 was found highly expressed in the follicular fluids of atretic follicles.It remains unclear that whether dysregulated IL-11/IL-11 receptors system were involved in the pathogenesis of POI.Methods:In the present study,patients with biochemical POI(bPOI)and control women who underwent in vitro infertilization and embro transfer(IVF-ET)due to tubal dysfunction or male factors,were recruited from the Reproductive Hospital Affiliated to Shandong University.Follicular fluids and granulosa cells were collected during oocyte retrival.The enzyme-linked immunosorbent assay(ELISA)was performed to analyze the level of IL-11 in the serum and follicular fluids of bPOI patients and control women.The total RNA were extracted from granulosa cells and quantitative real-time reverse transcription-polymerase chain reaction(qRT-PCR)were performed to compare the mRNA expression of IL-11RA between bPOI patients and control women.KGN cell lines were cultured in-vitro in different concentrations of recombinant human IL-11 to evaluate the effect of IL-11 on the viability and proliferation by EdU experiments,the apoptosis by Annexin V/PI staining,and estrodial production of granulosa cells.Results:There was relatively high expression of Il11 and Il11ra mRNA in ovarian granulosa cells and oocytes in mice.The level of IL-11 was quantified in serum and follicular fluids from patients with bPOI and control women by ELISA,and no significant differences were observed.IL11 was down-regulated and IL11RA was up-regulated in the granulosa cells of bPOI patients by qRT-PCR,which suggested an underlying role of dysregulated IL-11/IL-11 receptors in the pathogenesis of POI.By in-vitro additional supplement of IL-11,we found that higher concentration of IL-11 may promote the apoptosis of granulosa cells and impair their estradiol production.Conclusion:The dysregulation of IL-11/IL-11 receptors signaling pathway was observed in patients with bPOI,which might promote the apoptosis and impair the steroidogenesis of granulosa cells and hence result in follicle depletion and ovarian insufficiency.