ABSTRACT
RESEARCH QUESTION: What are the specific genetic alterations and associated network in endometriotic cells responsible for the disease pathogenesis? DESIGN: Case control experimental study involving 45 women with endometriosis who underwent laparoscopic surgery (case) and 45 normal samples from women undergoing total abdominal hysterectomy (control). The endometrial samples were subjected to whole exome sequencing (WES) of endometriotic tissue and copy number variation analysis. Validation of gene hits were obtained from WES using polymerase chain reaction techniques, immunological techniques, in-silico tools and transgenic cell line models. RESULTS: Germline heterozygous deletion of mRNA editing enzyme subunit APOBEC3B was identified in about 96% of endometriosis samples. The presence of germline deletion was confirmed with blood, endometrium and normal ovary samples obtained from the same patient. APOBEC3B deletions resulted in a hybrid protein that activates A1CF. APOBEC3B deletion can be a major cause of changes in the endometriotic microenvironment, and contributes to the pathogenesis and manifestation of the disease. The effect of APOBEC3B deletion was proved by in-vitro experiments in a cell line model, which displayed endometriosis-like characteristics. APOBEC3B germline deletion plays a major role in the pathogenesis of endometriosis, which is evident by the activation of A1CF, an increase in epithelial to mesenchymal transition, cellular proliferation, inflammation markers and a decrease in apoptosis markers. CONCLUSION: The deleterious effects caused by APOBEC3B deletion in endometriosis were identified and confirmed. These results might provide a base for identifying the complete pathogenetic mechanism of endometriosis, thereby moving a step closer to better diagnosis and treatment options.
ABSTRACT
BACKGROUND: Endometriosis is a complex gynaecological disorder that contributes to infertility, dysmenorrhea, dyspareunia, and other chronic issues. It is a multifactorial disease involving genetic, hormonal, immunological and environmental components. Endometriosis's pathogenesis remains unclear. AIM OF THE STUDY: was to analyse the polymorphisms in Interleukin 4, Interleukin 18, FCRL3 and sPLA2IIa genes to identify any significant association with the risk of endometriosis. MATERIAL AND METHODS: This study evaluated the polymorphism of -590 C/T in interleukin- 4(IL-4) gene, C607A in Interleukin - 18(IL-18) gene, -169T > C in FCRL3 gene and 763 C > G in sPLA2IIa gene in women with endometriosis. The case-control study included 150 women with endometriosis and 150 apparently healthy women as control subjects. DNA was extracted from peripheral blood leukocytes and endometriotic tissue of cases and blood samples for controls and further analysed by PCR amplification and then sequencing was carried out to find the allele and genotypes of the subjects and then to analyse the relationship between the gene polymorphisms and endometriosis. To evaluate the association of the different genotypes, 95% confidence intervals (CI) were calculated. RESULTS: Interleukin - 18 and FCRL3 gene polymorphisms of endometriotic tissue and blood samples of endometriosis (cases) showed significantly associated (OR = 4.88 [95% CI = 2.31-10.30], P > 0.0001) and (OR = 4.00 [95% CI = 2.2-7.33], P > 0.0001) when compared with normal blood samples. However, there was no significant difference in Interleukin - 4 and sPLA2IIa gene polymorphisms between control women and patients with endometriosis. CONCLUSIONS: The present study suggests that the IL-18 and FCRL3 gene polymorphisms are associated with a higher risk for endometriosis, which delivers valuable knowledge of endometriosis's pathogenesis. However, a larger sample size of patients from various ethnic backgrounds is necessary to evaluate whether these alleles have a direct effect on disease susceptibility.