HLA-G is upregulated in advanced endometriosis

Evaluation of HLA-DQ2 and HLA-DQ8 haplotypes in patients with endometriosis, A case-control study

OBJECTIVE

To evaluate the relationship between genetic haplotypes associated with celiac disease (Human Leucocyte Antigen [HLA] DQ2 and DQ8) with the diagnosis, clinical presentation, and location of endometriosis in Brazilian women.

METHOD

A retrospective cross-sectional study, was conducted in a Tertiary hospital.

PATIENTS

Women aged 18-50 years who underwent HLA-DQ2 and HLA-DQ8 haplotype analysis.

INTERVENTION

The patients were divided into endometriosis and control groups and evaluated for symptoms; endometriosis location, American Society for Reproductive Medicine (ASRM) stage, and the presence of anti-tissue transglutaminase IgA (anti-TgA), HLA-DQ2, and HLA-DQ8 markers.

RESULTS

A total of 434 consecutive patients with (n = 315) and without (n = 119) endometriosis were included. Pain and infertility were more frequent in the endometriosis group than in the control group. The presence of HLA-DQ2, HLA-DQ8, and anti-TgA was similar between both groups. The presence of HLA-DQ2 and HLA-DQ8 markers did not differ based on age, pain symptoms, ASRM stage, or endometriosis location.

CONCLUSION

Although there are similarities in inflammatory markers and pathophysiology between celiac disease and endometriosis, this study found no significant associations in the presence of HLA-DQ2 or HLA-DQ8 haplotypes and endometriosis.

The Antigen-Processing Pathway via Major Histocompatibility Complex I as a New Perspective in the Diagnosis and Treatment of Endometriosis

Endometriosis is a debilitating gynecological disease defined as the presence of endometrium-like epithelium and/or stroma outside the uterine cavity. The most commonly affected sites are the pelvic peritoneum, ovaries, uterosacral ligaments, and the rectovaginal septum. The aberrant tissue responds to hormonal stimulation, undergoing cyclical growth and shedding similar to appropriately located endometrial tissue in the uterus. Common symptoms of endometriosis are painful periods and ovulation, severe pelvic cramping, heavy bleeding, pain during sex, urination and bowel pain, bleeding, and pain between periods. Numerous theories have been proposed to explain the pathogenesis of endometriosis. Sampson's theory of retrograde menstruation is considered to be the most accepted. This theory assumes that endometriosis occurs due to the retrograde flow of endometrial cells through the fallopian tubes during menstruation. However, it has been shown that this process takes place in 90% of women, while endometriosis is diagnosed in only 10% of them. This means that there must be a mechanism that blocks the immune system from removing endometrial cells and interferes with its function, leading to implantation of the ectopic endometrium and the formation of lesions. In this review, we consider the contribution of components of the Major Histocompatibility Complex (MHC)-I-mediated antigen-processing pathway, such as the ERAP, TAP, LMP, LNPEP, and tapasin, to the susceptibility, onset, and severity of endometriosis. These elements can induce significant changes in MHC-I-bound peptidomes that may influence the response of immune cells to ectopic endometrial cells.

Soluble HLA-G (sHLA-G) measurement might be useful as an early diagnostic biomarker and screening test for gastric cancer

Gastric cancer (GC) is the fifth most frequent malignancy worldwide and has a high mortality rate related to late diagnosis. Although the gold standard for the GC diagnosis is endoscopy with biopsy, nonetheless, it is not cost-effective and is invasive for the patient. The Human leukocyte antigen G (HLA-G) molecule is a checkpoint of the immune response. Its overexpression in cancer is associated with immune evasion, metastasis, poor prognosis, and lower overall survival. We evaluate the plasma levels of soluble HLA-G, (sHLA-G) in patients with GC and benign gastric pathologies using an ELISA test. A higher concentration of sHLA-G in patients with GC than in those with benign pathologies, higher levels of plasma sHLA-G in women with GC compared with men and significant differences in the sHLA-G levels between the benign gastric pathologies evaluated, was our main findings. As no significant differences were found between the GC assessed stages in our study population, we suggest that sHLA-G is not an adequate marker for staging GC, but it does have diagnostic potential. In addition to providing information on the potential of sHLA-G as a diagnostic marker for GC, our study demonstrate that HLA-G molecules can be found in the membrane of exosomes, which highlights the need to perform studies with a larger number of samples to explore the functional implications of HLA-G positive exosomes in the context of gastric cancer, and to determine the clinical significance and possible applications of these findings in the development of non-invasive diagnostic methods.

Determination of soluble HLA-G serum levels in patients with adenomyosis and uterine fibroids before and after surgery

Adenomyosis is a benign gynaecological disease caused by the growth of endometrial tissue in the myometrium that affects approximately 30 % of child-bearing-age women. We evaluated the levels of soluble human leukocyte antigen G (sHLA-G) in the serum of patients with adenomyosis before and after treatment. Serum samples of 34 patients with adenomyosis and 31 patients with uterine fibroids were collected before and after the operation and were analysed for sHLA-G levels byELISAassay. The preoperative levels of serum sHLA-G in the adenomyosis group (28.05 ± 2.466 ng/ml) were significantly higher than those in the uterine fibroid group (18.53 ± 1.435 ng/ml) (P < 0.05). Serum sHLA-G levels in the adenomyosis group showed a decreasing trend at different time points after surgery (28.05 ± 14.38 ng/ml, 18.41 ± 8.34 ng/ml, and 14.45 ± 5.77 ng/ml). Adenomyosis patients who underwent total hysterectomy (n = 20) had a more significant decrease in sHLA-G levels in the early postoperative period (2 days post-operative) than those who underwent partial hysterectomy (n = 14). These results suggest that immunologic dysfunctions may be detected in patients with adenomyosis.

Identification of key modules and candidate genes associated with endometriosis based on transcriptome data via bioinformatics analysis

BACKGROUNDS

Endometriosis is a common disease in women, but the signaling pathways and genes involved remain unclear. This study screened genes that were differentially expressed in ectopic endometrium (EC) and eutopic endometrium (EU) in endometriosis and provided clues for subsequent experimental verification.

METHODS

Endometriosis samples were harvested from inpatients that underwent surgery from 2017 to 2019 with pathological evidence of endometriosis. We assessed the mRNA expression profiles in endometriosis and further conducted gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, Gene Set Enrichment Analysis (GSEA) and weighted gene co-expression network analysis (WGCNA) to identify potential biomarkers in endometriosis. Finally, we further validated hub genes using public databases and immunohistochemistry assays.

RESULTS

The upregulated DEGs of ectopic endometrium from endometriosis patients were mainly involved in cell adhesion, MAPK signaling, PI3K-Akt signaling pathways, cytokine receptor interactions, and epithelial-mesenchymal transformation (EMT)-associated signaling pathways. The downregulated DEGs between ectopic endometrium and eutopic endometrium were related to decidualization-associated genes in endometriosis. The correlated gene modules in eutopic endometrial cells were mainly enriched in cell adhesion, embryo implantation and inflammation. The eutopic and ectopic endometrial lesions in endometriosis were involved in the EMT process. Furthermore, we identified 18 co-expression modules during WGCNA analysis. Hub genes in the pale turquoise module were FOSB, JUNB, ATF3, CXCL2, FOS, etc. Significantly enriched KEGG pathways included the TNF, MAPK, foxO, oxytocin, and p53 signaling pathways. Enrichment pathways were directly related to immune surveillance, stem cell self-renewal, and epithelial-mesenchymal transformation. Several pathways and modules of endometriosis are related to cancer-associated pathways, which substantiates the correlation between endometriosis and various gynecological tumors.

CONCLUSIONS

Endometriosis was tightly correlated with EMT and fibrosis mediated by inflammatory immunity, cytokines, estrogen, kinases and protooncogene through transcriptomics. Overall, our findings lay the groundwork for understanding the pathogenesis of endometriosis and its relationship with malignant transformation.

Characterising the immune cell phenotype of ectopic adenomyosis lesions compared with eutopic endometrium: A systematic review

Inflammation is implicated in the symptomatology and the pathogenesis of adenomyosis. Injury at the endo-myometrial interface causes inflammation and may facilitate the invasion of endometrium into the myometrium, forming adenomyosis lesions. Their presence causes local inflammation, resulting in heavy menstrual bleeding, chronic pelvic pain, and subfertility. Immunological differences have been described in the eutopic endometrium from women with adenomyosis compared to healthy endometrium, and differences are also expected in the adenomyotic lesions compared with the correctly sited eutopic endometrium. This systematic review retrieved relevant articles from three databases with additional manual citation chaining from inception to 24th October 2022. Twenty-two eligible studies were selected in accordance with PRISMA guidelines. Risk of bias assessments were performed, and the findings presented thematically. Ectopic endometrial stroma contained an increased density of macrophages compared with eutopic endometrium in adenomyosis. This was associated with an increase in pro-inflammatory cytokines (IL-6, IL-8, ILβ-1, C-X-C Motif Chemokine Receptor 1(CXCR1), Monocyte Chemoattractant Protein-1 (MCP-1)), and an imbalance of anti-inflammatory cytokines (IL-22, IL-37). Cells in ectopic lesions also contained a higher levels of toll-like receptors and immune-mediated enzymes. However, the studies were heterogeneous, with inconsistent reporting of immune cell density within epithelial or stromal compartments, and inclusion of samples from different menstrual cycle phases in the same group for analysis. A detailed understanding of the immune cell phenotypes present in eutopic and ectopic endometrium in adenomyosis and associated dysregulated inflammatory processes will provide further insight into the pathogenesis, to enable identification of fertility-sparing treatments as an alternative to hysterectomy.

Natural Killer Cell Receptors and Endometriosis: A Systematic Review

Endometriosis is a chronic inflammatory disorder, characterized by the presence of endometrial cells outside the uterine cavity. An increasing number of studies correlate the immune system with endometriosis, particularly NK receptors (NKR), which have been suggested to play an essential role in the pathogenesis of the disease. This systematic review aims to enlighten the role of NKR in endometriosis. A literature search was performed independently by two reviewers, to identify studies assessing the role of NKR in endometriosis. In total, 18 studies were included. Endometriosis pathogenesis seems to be marked by the overexpression of NK inhibitor receptors (KIRS), namely, CD158a+, KIR2DL1, CD94/NKG2A, PD-1, NKB1, and EB6, and inhibiting ligands such as PD-L1, HLA-E, HLA-G, and HLA-I. Concurrently, there is a decrease in NK-activating receptors and natural cytotoxicity receptors (NCRs), such as NKp46, NKp30, and NKG2D. The immune shift from NK surveillance to NK suppression is also apparent in the greater relative number of ITIM domains compared with ITAM domains in NKRs. In conclusion, NK receptor activity seems to dictate the immunocompetency of women to clear endometriotic cells from the peritoneal cavity. Future research could explore NKRs as therapeutic targets, such as that which is now well established in cancer therapy through immunotherapy.

Current Knowledge on Endometriosis Etiology: A Systematic Review of Literature

Objective

To review the mechanisms of endometriosis development, including those related to epigenetic mutations, cellular dysregulation, inflammatory processes, and oxidative stress.

Methods

A systematic literature review regarding current aspects of endometriosis etiology, genesis and development was performed using the PubMed, Google Scholar, and eLibrary databases. Keywords included endometriosis, etiology, development, genesis, associations and mechanisms. A multilingual search was performed.

Results

Several mechanisms underline the pathophysiological pathways for endometriosis development. Epigenetic mutations, external and internal influences, and chronic conditions have a significant impact on endometriosis development, survival and regulation. Several historically valid theories on endometriosis development were discussed, as well as updated findings.

Conclusion

Despite recent advances, fundamental problems in understanding endometriosis remain unresolved. The identification of unknown circulating epithelial progenitors or stem cells that are responsible for epithelial growth in both the endometrium and endometriotic foci seems to be the next step in solving these questions.

Eutopic endometrium from women with endometriosis and chlamydial endometritis share immunological cell types and DNA repair imbalance: A transcriptome meta-analytical perspective

The aim of this study was to identify the key similarities between the eutopic endometrium of women with endometriosis and chlamydia-induced endometritis taking into account tissue microenvironment heterogeneity, transcript gene profile, and enriched pathways. A meta-analysis of whole transcriptome microarrays was performed using publicly available data, including samples containing both glandular and stromal endometrial components. Control samples were obtained from women without any reported pathological condition. Only samples obtained during the proliferative menstrual phase were included. Cellular tissue heterogeneity was predicted using a method that integrates gene set enrichment and deconvolution approaches. The batch effect was estimated by principal variant component analysis and removed using an empirical Bayes method. Differentially expressed genes were identified using an adjusted p-value < 0.05 and fold change = 1.5. The protein-protein interaction network was built using the STRING database and interaction score over 400. The Molecular Signatures Database was used to analyse the functional enrichment analysis. Both conditions showed similarities in cell types in the microenvironment, particularly CD4⁺ and CD8⁺ Tem cells, NKT cells, Th2 cells, basophils, and eosinophils. With regards to the regulation of cellular senescence and DNA integrity/damage checkpoint, which are commonly enriched pathways, 21 genes were down-regulated and directly related to DNA repair. Compared to the endometriosis samples, some chlamydial endometritis samples presented a lack of enriched immune pathways. Our results suggest that both conditions show similar distributions of microenvironment cell types, the downregulation of genes involved in DNA repair and cell cycle control, and pathways involved in immune response evasion.

Inhibitory KIR2DL2 Gene: Risk for Deep Endometriosis in Euro-descendants

Endometriosis (EDT) is an inflammatory disease characterized by implantation/growth of endometrial tissue, glands, and/or stroma, outside the uterus. Reduced NK cell cytotoxic activity has been implicated in its pathogenesis, together with other immunologic alterations. We investigated the influence of KIR gene polymorphisms and their HLA ligand combinations in deep endometriosis (DE) susceptibility. One hundred sixty women with a histological diagnosis of DE and 202 control women without the disease, who underwent laparoscopy, were enrolled. The DE group was subdivided into initial (I/II; n = 60) and advanced stages (III/IV, n = 100). KIR and HLA class I gene polymorphisms were typed by PCR-SSP and sequence-based-typing (SBT), respectively. We observed a significant association of KIR2DL2, an inhibitory gene of B haplotype, conferring risk for DE in Euro-descendants. Positive associations of Bx haplotype and centromeric AB segments were also found. However, no association with KIR-HLA ligand combination was observed. Our data suggest KIR2DL2 gene to be a relevant factor favoring NK inhibition in DE in Euro-descendants, contributing to the defective NK cytotoxic activity and impaired clearance of ectopic endometrial cells in the disease.

Pathogenesis of bowel endometriosis

The pathogenesis of bowel endometriosis is multifactorial. There is a predilection for disease of the rectum/sigmoid colon because refluxed endometrium is more likely to settle in the pouch of Douglas and its movement is delimited by the sigmoid colon, in addition to the close proximity of the rectum/sigmoid to posterior extrinsic uterine adenomyosis and to ovarian endometriomas. Once situated, deep bowel endometriosis has features of invasion, angiogenesis, and fibrosis (repeated tissue injury and repair), with emerging research on oxidative stress and the microbiome. Furthermore, deep bowel endometriosis is associated with neurogenesis and/or the recruitment of local nerve fibers and is capable of invading existing nerves, which in turn may also promote fibrosis. Recently, somatic cancer driver mutations (e.g., in KRAS) were identified in deep bowel endometriosis, which may play a role in the genetic/epigenetic theory of endometriosis. In the future, it is possible that bowel endometriosis could be classified based on molecular features.

NK Cells as Potential Targets for Immunotherapy in Endometriosis

Endometriosis is a common gynecological disease defined by the presence of endometrial-like tissue outside the uterus, most frequently on the pelvic viscera and ovaries, which is associated with pelvic pains and infertility. It is an inflammatory disorder with some features of autoimmunity. It is accepted that ectopic endometriotic tissue originates from endometrial cells exfoliated during menstruation and disseminating into the peritoneum by retrograde menstrual blood flow. It is assumed that the survival of endometriotic cells in the peritoneal cavity may be partially due to their abrogated elimination by natural killer (NK) cells. The decrease of NK cell cytotoxic activity in endometriosis is associated with an increased expression of some inhibitory NK cell receptors. It may be also related to the expression of human leukocyte antigen G (HLA-G), a ligand for inhibitory leukocyte immunoglobulin-like receptor subfamily B member 1 (LILRB1) receptors. The downregulated cytotoxic activity of NK cells may be due to inhibitory cytokines present in the peritoneal milieu of patients with endometriosis. The role of NK cell receptors and their ligands in endometriosis is also confirmed by genetic association studies. Thus, endometriosis may be a subject of immunotherapy by blocking NK cell negative control checkpoints including inhibitory NK cell receptors. Immunotherapies with genetically modified NK cells also cannot be excluded.