Expression of Pirna in Tissues of Ovarian Endometriosis Cysts

Study Objective To identify the expression of PIWI associated RNA (piRNA) in tissues of endometrium and endometrioid ovarian cysts and to evaluate differences in the expression of piRNA between eutopic and ectopic endometrium. Design Prospective observational cohort study; Level II-1. Setting Federal State Budget Institution «The National Medical Research Center for Obstetrics, Gynecology and Perinatology», Moscow. Patients or Participants The study included 21 patients of reproductive age (30.27 ± 3.78 years) with endometrioid ovarian cysts. Paired samples of endometrial tissues were collected during surgery in the proliferative phase of menstrual cycle. Tissue samples for further analysis were selected after histological examination. The analysis of piRNA expression was carried out by the new generation sequencing on the Illumina platform, followed by processing of the data by bioinformatics analysis. Interventions Laparoscopic surgery for endometriod ovarian cysts and endometrial biopsy followed by histopathologic and piRNA expression analysis of obtained tissue. Measurements and Main Results According to the sequencing data, 197 piRNA were identified in the tissues of the eutopic endometrium and endometrioid ovarian cysts. The analysis of differential expression revealed predominantly reduced expression of piRNA in the ectopic endometrium relative to the eutopic endometrium. In total 30 differentially expressed piRNA were identified, including 4 with increased and 26 with reduced expression. Using bioinformatic methods, possible gene targets of differentially expressed piRNA were found. Functional analysis of potential targets of differentially expressed piRNA revealed signaling pathways and cellular processes that may contribute to the development of endometriosis. Conclusion The data obtained suggest that alterations in piRNA expression of ectopic endometrium and subsequent disturbances in the expression of their target genes may be significant link in our search for the pathogenesis of endometriosis.