Higher Follicular Fluid Progesterone Down-regulated HPGD and COX2 in Granulosa Cells via Suppressing NF-кB Signaling in Endometriosis

Abstract Background: Luteinized unruptured follicular follicle syndrome (LUFS) is a special type of ovulatory dysfunction and a common cause of infertility. It is estimated that its prevalence is 13% ~ 73% in endometriosis patients. Increasing evidences prove that LUFS is one of the reasons for endometriosis-related infertility. Any alteration in FF components and GCs in endometriosis may influence the developing oocyte and ovulation. This study aimed to explore the effect of local elevated progesterone in follicular fluid (FF) on ovulation in endometriosis patients.Methods: A Prospective study with matched pairs design was conducted at a reproductive medicine center between July 2017 and January 2018 in patients undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection treatment (ICSI), while granulosa tumor-like cell line KGN (Bena culture collection, China) was used as in vitro cell model. Alterations in follicular and peritoneal fluid (PF) components identified with metabolomics analyses; Differentially expressed genes in GCs identified with transcriptome analysis; Polymerase chain reaction (PCR), western blot, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence were used to determine the expression of progesterone, NF-кB related genes, HPGD and COX-2; NF-кB binding identified with chromatin immunoprecipitation (ChIP).Results: Patients with endometriosis exhibited a significantly higher basal serum progesterone level, higher serum level of progesterone on trigger day and higher progesterone expression level in FF and PF. GCs from endometriosis patients revealed decreased expression of HPGD, COX-2 and suppressed NF-кB signaling, as manifested by decreased expressions of IL1R1 and IRAK3. Similarly, progesterone treatment in vitro down-regulated HPGD and COX2 expression and suppressed NF-кB signaling in KGN cells in a dose dependent manner, as manifested by decreased expressions of IL1R1, IRAK3, reduced pIкBα/IкBα ratio and nucleus translocation of p65. TNF-α, by contrast, increased expression of IL1R1, IRAK3, pIкBα, p65 and HPGD in KGN cells. Furthermore, one potential p65 binding site was identified in the promoter region of HPGD by chromatin immunoprecipitation.Conclusion: Endometriosis showed repression of NF-кB pathways and down-regulation of HPGD and COX2, which play important roles in the process of ovulation by participating in the metabolism of prostaglandin E2 (PGE2), in granulosa cells (GCs) due to elevated progesterone in FF.