Aberrant methylation of the IL-12B promotor region contributes to the risk of developing ovarian endometriosis

The Dysregulated IL-23/TH17 Axis in Endometriosis Pathophysiology

Endometriosis is a chronic inflammatory disease in which endometrial-like tissue grows ectopically, resulting in pelvic pain and infertility. IL-23 is a key contributor in the development and differentiation of TH17 cells, driving TH17 cells toward a pathogenic profile. In a variety of inflammatory and autoimmune disorders, TH17 cells secrete proinflammatory cytokines, including IL-17, contributing to disease pathophysiology. Our studies and others have implicated IL-17 and TH17 cell dysregulation in endometriosis, which is associated with disease severity. In this article, we address whether IL-23-driven TH17 cells contribute to cardinal features of lesion proliferation, vascularization, and inflammation in endometriosis using patient samples, representative cell lines, and our established mouse model of endometriosis. The results indicated dysregulated expression of key genes in the IL-23/TH17 axis in patient ectopic and eutopic endometrial samples and increased IL-23 protein in patient plasma compared with controls. In vitro studies using primary human TH cells determined that rIL-23 mixture treatment increased pathogenic TH17 cell frequency. Similarly, rIL-23 treatment of cell lines (12Z cells, EECCs, HUVECs, and hESCs) representative of the endometriotic lesion microenvironment increased cytokines and growth factors, which play a role in lesion establishment and maintenance. In a syngeneic mouse model of endometriosis, rIL-23 treatment altered numbers of myeloid and T cell subsets in peritoneal fluid and increased giant cells within the lesion. Lesions from rIL-23-treated mice did not reveal significant alterations in proliferation/vascularization, although trends of increased proliferation and vascularization were observed. Collectively, these findings provide insights into the impact of the IL-23/TH17 axis on local immune dysfunction and broadly on endometriosis pathophysiology.

Omics-based novel strategies in the diagnosis of endometriosis

Endometriosis, an enigmatic and chronic disorder, is considered a debilitating condition despite being benign. Globally, this gynecologic disorder affects up to 10% of females of reproductive age, impacting almost 190 million individuals. A variety of genetic and environmental factors are involved in endometriosis development, hence the pathophysiology and etiology of endometriosis remain unclear. The uncertainty of the etiology of the disease and its complexity along with nonspecific symptoms have led to misdiagnosis or lack of diagnosis of affected people. Biopsy and laparoscopy are referred to as the gold standard for endometriosis diagnosis. However, the invasiveness of the procedure, the unnecessary operation in disease-free women, and the dependence of the reliability of diagnosis on experience in this area are considered the most significant limitations. Therefore, continuous studies have attempted to offer a noninvasive and reliable approach. The recent advances in modern technologies have led to the generation of large-scale biological data sets, known as -omics data, resulting in the proceeding of the -omics century in biomedical sciences. Thereby, the present study critically reviews novel and noninvasive biomarkers that are based on -omics approaches from 2020 onward. The findings reveal that biomarkers identified based on genomics, epigenomics, transcriptomics, proteomics, and metabolomics are potentially able to diagnose endometriosis, predict prognosis, and stage patients, and potentially, in the near future, a multi-panel of these biomarkers will generate clinical benefits.

A Systematic Review of Epigenetics of Endometriosis

Objective

To assess the current literature evaluating the epigenetics of endometriosis in humans.

Evidence Review

A systematic review was conducted in accordance with the PRISMA guidelines within PubMed, EBSCOhost, Cochrane Library, Embase, Scopus, and Web of Science Core Collection. A comprehensive search strategy was developed by a data informationist. Observational and interventional studies assessing epigenetics in humans published in English up to January 15th, 2023, were included. Two reviewers independently screened studies evaluating the role of epigenetics in endometriosis. The risk of bias was assessed using Cochrane RoB 2.0 tool and the Newcastle-Ottawa scale. Extracted data were analyzed descriptively.

Results

We identified 18.639 studies, of which 57 were included, comprising 1.623 patients with endometriosis and 1.243 controls. Among the 57 studies included, 50 (88%) were case-control studies, and 7 (12%) were cross-sectional. Fifty-nine percent of the studies were Asian, 25% were from America, 14% were European, and 2% were from Africa. Acetylation and methylation were the two main key histone modifications that were centered in this review. Accordingly, we classified the studies as those focusing on genome-wide methylation and those on histone acetylation. Several studies identified an association between endometriosis and hypermethylated genes, including the PGR-B, SF-1, and RASSF1A. The genes HOXA10, COX-2, IL-12B, and GATA6 were found to be hypomethylated in endometriotic tissue by several studies. In regards to histone modification, multiple studies reported that the acetylation levels of histones H3 and H4 affect multiple genes associated with endometriosis. In addition, HDAC2 was found to be elevated in endometriosis patients in two studies.

Conclusion

Several studies reported a significant difference between specific genes' methylation levels in endometrial biopsies and normal tissue, which suggests that DNA methylation may play an important role in the modulation of the genotype in endometriotic tissue. Acetylation and methylation are the two key histone modifications leading to differential gene expression in endometriotic tissues. The alterations in gene expression reported by the 57 studies can have direct implications on cell cycle growth, cell cycle arrest, and apoptosis and, therefore, might play a key role in the pathogenesis of endometriosis. This review offers insight that histone modifications need further research to evaluate their role as potential biomarkers and treatment targets for endometriosis. Although several key similarities were reported, there were some disagreements among the results, which might be attributable to the heterogeneity between studies. Further research with a more robust standardization is needed to validate the epigenetic changes in endometriosis.

Association between gene polymorphisms of IL-12, IL-12 receptor and IL-27 and organ involvement in Iranian endometriosis patients

Endometriosis is an inflammatory disease characterized by the presence of ectopic endometrial tissue, immune cell dysfunction and abnormal cytokine secretion. In addition to immunological factors, genetic variations that influence endometriosis severity and cytokine expression levels play important roles in the pathogenesis of this disease. Interleukin-12 (IL-12), specifically its p40 subunit encoded by IL-12B gene and the interleukin-12 receptor β1 (IL-12Rβ2) chain of its receptor, as well as interleukin-27 (IL-27) are important in the establishment of endometriosis. So, in this study, we measured IL-12 and IL-27 serum levels and investigated the possible links between IL-12B rs3212227, IL-12Rβ2 rs3790565 and IL-27 rs153109 polymorphisms and the risk of developing endometriosis in a group of Iranian women. In this case-control study, 162 endometriosis patients and 151 healthy women were included and tested for the aforementioned polymorphisms using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The enzyme-linked immunosorbent assay (ELISA) method was also used to measure IL-12 and IL-27 serum levels. Although there was no statistically significant association between the genotypes and alleles of the studied polymorphisms and the development of endometriosis in general, the AA genotype of IL-12B rs3212227 showed a significant association with uterine endometriosis when compared to AC+CC genotypes (p = .04, CI = 0.270-0.988, OR = 0.517). Indeed, the AA genotype of the IL-12B rs3212227 single nucleotide polymorphism (SNP) may be linked with a lower risk of developing uterine endometriosis. There was no significant difference in IL-27 levels between the two studied groups (p = .49), and IL-12 levels were undetectable in both groups. In conclusion, the AA genotype of IL-12B rs3212227 might be associated with a decreased risk of uterine involvement in endometriosis patients.

Aberrant Methylation of miR-34b and IL-12B mRNA Promoters Contributes to the Reduced Severity of Ankylosing Spondylitis

DNA methylation of Interleukin-12B (IL-12B) and miR-34b was proved to affect the expression of IL-12B and miR-34b, which were found to be involved in the pathogenesis of ankylosing spondylitis (AS). However, the molecular mechanisms underlying the role of IL-12B and miR-34b in AS remain to be explored. AS patients were divided into four groups according to their status of DNA methylation of miR-34b and IL-12B by bisulfite sequencing: HYPER-miR-34b + HYPO-IL-12B, HYPER-miR-34b + HYPER-IL-12B, HYPO-miR-34b + HYPER-IL-12B and HYPO-miR-34b + HYPO-IL-12B groups. Functional indicators were examined for patients with different status of DNA methylation in their miR-34b and IL-12B promoters. QPCR was performed to examine the expression of miR-34b and IL-12B mRNA under different conditions. ELISA was used to measure the expression of IL-12B p40 in the peripheral blood. Western blot was used to analyze the expression of IL-12B proteins. Luciferase assay was carried out to explore the suppressive role of miR-34b in IL-12B expression. The level of Ankylosing Spondylitis Disease Activity Score with C-reactive protein (ASDAS-CRP) was gradually increased in HYPER-miR-34b + HYPO-IL-12B,HYPER-miR-34b + HYPER-IL-12B,HYPO-miR-34b + HYPER-IL-12B and HYPO-miR-34b + HYPO-IL-12B groups, whereas the levels of Bath Ankylosing Spondylitis Functional Index (BASFI) and Bath Ankylosing Spondylitis Metrology Index (BASMI) were significantly elevated in the HYPO-miR-34b + HYPO-IL-12B group and diminished in the HYPER-miR-34b + HYPO-IL-12B group. The expression of miR-34b in the PBMCs and peripheral blood was remarkably higher in the HYPER-miR-34b + HYPO-IL-12B and HYPER-miR-34b + HYPER-IL-12B groups, whereas the expression of IL-12B was gradually decreased in the HYPER-miR-34b + HYPO-IL-12B, HYPER-miR-34b + HYPER-IL-12B, HYPO-miR-34b + HYPER-IL-12B and HYPO-miR-34b + HYPO-IL-12B groups. Luciferase assays with the transfection of miR-34b precursors suggested that miR-34b strongly suppressed the expression of IL-12B in THP-1 cells. In conclusion, our study demonstrated that hypermethylated miR-34b promoter led to evident upregulation of miR-34b, thus inhibiting the expression of IL-12B and alleviated the severity of ankylosing spondylitis by reducing the levels of factors including ASDAS-CRP, BASFI and BASMI.