Endometriosis may be generated by mimicking the ontogenetic development of the female genital tract

WNT4 (rs7521902 and rs16826658) polymorphism and its association with endometriosis - A systematic review and meta-analysis

IMPORTANCE

This systematic review supports the involvement of the WNT4 gene in the pathophysiology of endometriosis.

OBJECTIVE

To conduct a systematic review and meta-analysis on WNT4 rs7521902 and rs16826658 polymorphism associated with endometriosis based on multi-ethnic case-control studies.

DATA SOURCES

Comprehensive searching was performed using Medline, Embase, and Google Scholar.

STUDY SELECTION AND SYNTHESIS

Keywords used for searching using Boolean operators are endometriosis, WNT4, and polymorphism. This review followed PRISMA guidelines, and meta-analysis was conducted in STATA18.

MAIN OUTCOMES

WNT4 polymorphisms identified in this review were rs7521902, rs16826658, rs2235529, rs3820282, and rs12037376.

RESULTS

A total of 250 studies were identified through databases; 10 were eligible for this review, and eight were included in the meta-analysis. Two WNT4 polymorphisms (rs7521902 and rs16826658) were analysed in the meta-analysis. A lower risk of odds in having endometriosis was apparent in the CC genotype of rs7521092 polymorphism with a pooled OR of 0.86 (0.76, 0.99). Most articles were high-quality case-control studies and were at low risk of bias.

CONCLUSION

This study highlighted the association of WNT4 polymorphisms (rs7521092) and endometriosis across Latin America, Europe, and Asian populations.

RELEVANCE

Following the completion of the Human Genome Project, many genetic aspects of endometriosis were revealed, including the discovery of single nucleotide polymorphisms (SNPs). However, due to a lack of replications and conflicting results between studies, the conclusion of the endometriosis genetic pathway needed to be completed. This finding of WNT4 showed that its association with endometriosis was valid even in varied ethnicities, indicating a general genetic aspect of disease across populations. Nevertheless, further studies are needed to confirm this finding, including functional biological and longitudinal studies.

Molecular Mechanisms of Endometriosis Revealed Using Omics Data

Endometriosis is a gynecological disorder prevalent in women of reproductive age. The primary symptoms include dysmenorrhea, irregular menstruation, and infertility. However, the pathogenesis of endometriosis remains unclear. With the advent of high-throughput technologies, various omics experiments have been conducted to identify genes related to the pathophysiology of endometriosis. This review highlights the molecular mechanisms underlying endometriosis using omics. When genes identified in omics experiments were compared with endometriosis disease genes identified in independent studies, the number of overlapping genes was moderate. However, the characteristics of these genes were found to be equivalent when functional gene set enrichment analysis was performed using gene ontology and biological pathway information. These findings indicate that omics technology provides invaluable information regarding the pathophysiology of endometriosis. Moreover, the functional characteristics revealed using enrichment analysis provide important clues for discovering endometriosis disease genes in future research.

Malignant transformation of endometriosis in a laparoscopic trocar site a case report

BACKGROUND

Malignant transformation of endometriosis is infrequent at the laparoscopic trocar site. Although malignant transformation is uncommon, it must be acknowledged in order to achieve radical resection.

CASE PRESENTATION

We report on a 54-year-old woman with trocar site endometriosis 2 years after laparoscopic ovarian endometrial resection. Physical examination revealed a subcutaneous solid tumor with a diameter of 3 cm surrounding the scar of laparoscopic surgery in the right lower abdomen. Transabdominal ultrasonography showed a cystic tumor in the subcutaneous adipose layer of the right lower abdomen. The pathological diagnosis was poorly differentiated endometrioid carcinoma. Hysterectomy, bilateral salpingo-oophorectomy and pelvic lymphadenectomy were then performed. Histological examination revealed mixed endometrioid carcinoma and clear cell carcinoma. After six cycles of chemotherapy, computed tomography showed no signs of recurrence.

CONCLUSIONS

Malignant transformation of laparoscopic endometriosis is very uncommon, and the diagnosis and stage are determined by clinical manifestations and imaging examination. The main therapy methods are radical surgery combined with neoadjuvant chemotherapy and adjuvant radiotherapy. At the same time, reducing iatrogenic abdominal incision implantation is an effective prevention method.

The Genetic Background of Endometriosis: Can ESR2 and CYP19A1 Genes Be a Potential Risk Factor for Its Development?

Endometriosis is defined as the presence of endometrial foci, localized beyond their primary site, i.e., the uterine cavity. The etiology of this disease is rather complex. Its development is supported by hormonal, immunological, and environmental factors. During recent years, particular attention has been focused on the genetic mechanisms that may be of particular significance for the increased incidence rates of endometriosis. According to most recent studies, ESR2 and CYP19A1 genes may account for the potential risk factors of infertility associated with endometriosis. The paper presents a thorough review of the latest reports and data concerning the genetic background of the risk for endometriosis development.

Genetic Characterization of Endometriosis Patients: Review of the Literature and a Prospective Cohort Study on a Mediterranean Population

The pathogenesis of endometriosis is unknown, but some evidence supports a genetic predisposition. The purpose of this study was to evaluate the recent literature on the genetic characterization of women affected by endometriosis and to evaluate the influence of polymorphisms of the wingless-type mammalian mouse tumour virus integration site family member 4 (WNT4), vezatin (VEZT), and follicle stimulating hormone beta polypeptide (FSHB) genes, already known to be involved in molecular mechanisms associated with the proliferation and development of endometriotic lesions in the Sardinian population. Materials and Methods: In order to provide a comprehensive and systematic tool for those approaching the genetics of endometriosis, the most cited review, observational, cohort and case-control studies that have evaluated the genetics of endometriosis in the last 20 years were collected. Moreover, 72 women were recruited for a molecular biology analysis of whole-blood samples—41 patients affected by symptomatic endometriosis and 31 controls. The molecular typing of three single nucleotide polymorphisms (SNPs) was evaluated in patients and controls: rs7521902, rs10859871 and rs11031006, mapped respectively in the WNT4, VEZT and FSHB genes. In this work, the frequency of alleles, genotypes and haplotypes of these SNPs in Sardinian women is described. Results: From the initial search, a total of 73 articles were chosen. An analysis of the literature showed that in endometriosis pathogenesis, the contribution of genetics has been well supported by many studies. The frequency of genotypes observed in the groups of the study population of 72 women was globally coherent with the law of the Hardy–Weinberg equilibrium. For the SNP rs11031006 (FSHB), the endometriosis group did not show an increase in genotypic or allelic frequency due to this polymorphism compared to the control group (p = 0.9999, odds ratio (OR) = 0.000, 95% confidence interval (CI), 0.000–15.000 and p = 0.731, OR = 1639, 95% CI, 0.39–683, respectively, for the heterozygous genotype and the polymorphic minor allele). For the SNP rs10859871 (VEZT), we found a significant difference in the frequency of the homozygous genotype in the control group compared to the affected women (p = 0.0111, OR = 0.0602, 95% CI, 0.005–0.501). For the SNP rs7521902 (WNT4), no increase in genotypic or allelic frequency between the two groups was shown (p = 0.3088, OR = 0.4133, 95% CI, 0.10–1.8 and p = 0.3297, OR = 2257, 95% CI, 0.55–914, respectively, for the heterozygous genotype and the polymorphic minor allele). Conclusion: An analysis of recent publications on the genetics of endometriosis showed a discrepancy in the results obtained in different populations. In the Sardinian population, the results obtained do not show a significant association between the investigated variants of the genes and a greater risk of developing endometriosis, although several other studies in the literature have shown the opposite. Anyway, the data underline the importance of evaluating genetic variants in different populations. In fact, in different ethnic groups, it is possible that specific risk alleles could act differently in the pathogenesis of the disease.

Recent advances in mammalian reproductive biology

Reproductive biology is a uniquely important topic since it is about germ cells, which are central for transmitting genetic information from generation to generation. In this review, we discuss recent advances in mammalian germ cell development, including preimplantation development, fetal germ cell development and postnatal development of oocytes and sperm. We also discuss the etiologies of female and male infertility and describe the emerging technologies for studying reproductive biology such as gene editing and single-cell technologies.

Genetics of endometriosis: a comprehensive review

This review aimed to critically evaluate the review, observational, cohort, and case-control studies performed so far in order to assess the association between endometriosis and genetics. The search strategies used included an online search of the MEDLINE database and a manual search of relevant publications and reviews. Additional reports were collected by systematically reviewing all references from the retrieved papers. Family studies have long suggested that genetic factors play a role in the etiology of endometriosis. Nevertheless, until now, studies on candidate genes have revealed inconsistent and contradictory evidence, leading to more questions rather than clear answers. It is possible that recent technological improvements in genetic evaluation could allow for a better understanding of the pathogenic mechanisms of endometriosis in the near future.

Pathogenomics of Endometriosis Development

For over 100 years, endometriosis, as a chronic, estrogen-dependent, inflammatory, heritable disease affecting approximately 5–10% of women in reproductive age has been the focus of clinicians and scientists. In spite of numerous environmental, genetic, epigenetic, endocrine, and immunological studies, our knowledge of endometriosis is still fragmentary, and its precise pathophysiology and pathogenomics remain a mystery. The implementation of new technologies has provided tremendous progress in understanding the many intrinsic molecular mechanisms in the development of endometriosis, with progenitor and stem cells (SCs) of the eutopic endometrium as the starting players and endometriotic lesions as the final pathomorphological trait. Novel data on the molecular, genetic, and epigenetic mechanisms of the disease are briefly outlined. We hypothesize the existence of an endometriosis development genetic program (EMDP) that governs the origin of endometrium stem cells programmed for endometriosis (1), their transition (metaplasia) into mesenchymal SCs (2), and their invasion of the peritoneum and progression to endometriotic lesions (3). The pros and cons of the recent unifying theory of endometriosis are also discussed. Complex genomic and epigenetic interactions at different stages of the endometriosis process result in different forms of the disease, with specific features and clinical manifestations. The significance of the EMDP in elaborating a new strategy for endometriosis prediction, prevention, and treatment is discussed.

Molecular and Cellular Pathogenesis of Endometriosis

BACKGROUND

A substantial body of studies supports the view that molecular and cellular features of endometriotic lesions differ from those of eutopic endometrium. Apart from that, evidence exists that the eutopic endometrium from pa-tients with endometriosis differs from that of females without endometriosis.

OBJECTIVE

Aberrant expression profiles include a number of non-steroid signaling pathways that exert their putative influ-ence on the pathogenesis of endometriosis at least in part via crosstalk(s) with estrogen-mediated mechanisms. A rational to focus research on non-steroid signal pathways is that they might be remunerative targets for the development and selection of novel therapeutics to treat endometriosis possibly without affecting estrogen levels.

RESULTS AND CONCLUSION

In this article, we describe molecular and cellular features of endometriotic lesions and focus on the canonical WNT/β-signaling pathway, a key regulatory system in biology (including stem cell homeostasis) and often in pathophysiological conditions such as endometriosis. Recently emerged novel biological concepts in signal transduction and gene regulation like exosomes and microRNAs are discussed in their putative role in the pathogenesis of endometriosis.

Back to the Original Question in Endometriosis: Implantation or Metaplasia?

The pathogenesis of some forms of endometriosis is still controversial. Different research approaches have been used to clarify this issue and an intense debate has derived over the years among scientists. This paper presents and discusses aged and modern ideas derived from various observations in different research areas on this specific topic. More specifically, data derived from histological results, animal studies, anatomical findings and basic research activity are presented.

Although an increasing body of evidence tends to support the implantation theory, which currently represents the most recognized pathogenic model for endometriosis, some aspects of this disease remain obscure and the scientific and medical communities have still not made significant progress in terms of completely elucidating the histogenesis of some forms of the disease.

The role of gene polymorphisms in endometriosis

Endometriosis is a benign gynecologic disorder, affecting up to 10% of women, characterized by the presence of functional endometrial tissue at ectopic positions generally within the peritoneum. It is a heritable condition influenced by multiple genetic and environmental factors, with an overall heritability estimated at approximately 50%. In this study, we investigated whether single nucleotide polymorphisms (SNPs) rs7521902, rs10859871 and rs11031006, mapping to WNT4, VEZT and FSHB genetic loci, respectively, are associated with risk for endometriosis in a Greek population. This study included 166 women with histologically confirmed endometriosis diagnosed through surgery and 150 normal controls. Genotyping of the rs7521902, rs10859871 and rs11031006 SNPs was performed with Taqman primer/probe sets. A significant association was detected with the AC genotype of rs7521902 (WNT4) in patients with stage III and IV disease only. Evidence for association with endometriosis was also found for the AC genotype of the rs10859871 of VEZT. Notably, a significant difference in the distribution of the AG genotype and the minor allele A of FSHB rs11031006 SNP was found between the endometriosis patients and controls. We found a genetic association between rs11031006 (FSHB) SNP and endometriosis. WNT4 and VEZT genes constitute the most consistently associated genes with endometriosis. In the present study, an association of rs7521902 (WNT4) and rs10859871 (VEZT) was confirmed in women with endometriosis at the genotypic but not the allelic level.

Beyond Endometriosis Genome-Wide Association Study: From Genomics to Phenomics to the Patient

Endometriosis is a heritable, complex chronic inflammatory disease, for which much of the causal pathogenic mechanism remains unknown. Genome-wide association studies (GWAS) to date have identified 12 single nucleotide polymorphisms at 10 independent genetic loci associated with endometriosis. Most of these were more strongly associated with revised American Fertility Society stage III/IV, rather than stage I/II. The loci are almost all located in intergenic regions that are known to play a role in the regulation of expression of target genes yet to be identified. To identify the target genes and pathways perturbed by the implicated variants, studies are required involving functional genomic annotation of the surrounding chromosomal regions, in terms of transcription factor binding, epigenetic modification (e.g., DNA methylation and histone modification) sites, as well as their correlation with RNA transcription. These studies need to be conducted in tissue types relevant to endometriosis-in particular, endometrium. In addition, to allow biologically and clinically relevant interpretation of molecular profiling data, they need to be combined and correlated with detailed, systematically collected phenotypic information (surgical and clinical). The WERF Endometriosis Phenome and Biobanking Harmonisation Project is a global standardization initiative that has produced consensus data and sample collection protocols for endometriosis research. These now pave the way for collaborative studies integrating phenomic with genomic data, to identify informative subtypes of endometriosis that will enhance understanding of the pathogenic mechanisms of the disease and discovery of novel, targeted treatments.

Florid Cystic Endosalpingiosis (Müllerianosis) in Pregnancy

Cystic endosalpingiosis refers to the existence of heterotopic cystic müllerian tissue resembling structures of the fallopian tubes. We report a case of florid cystic endosalpingiosis discovered in a pregnant woman during a scheduled cesarean section and review the current knowledge of this disease. A 30-year-old woman with a twin pregnancy attended the hospital day unit at term. The first twin was in a breech presentation and a cesarean section was scheduled. During the procedure the uterine fundus and part of the body were seen completely seeded with multitude of cyst-like structures resembling hydatids of Morgagni. The immunohistochemistry analysis showed a positive expression for PAX8 (Box-8), CK7, and estrogen and progesterone receptors. The lesions did not disappear after pregnancy. Cystic endosalpingiosis should be always borne in mind, even in pregnancy, when it comes to making the differential diagnosis of a pelvic or systemic multicystic mass.

Genetics of endometriosis

Endometriosis is a heritable complex disorder that is influenced by multiple genetic and environmental factors. Identification of these genetic factors will aid a better understanding of the underlying biology of the disease. In this article, we describe different methods of studying genetic variation of endometriosis, summarize results from genetic studies performed to date and provide recommendations for future studies to uncover additional factors contributing to the heritable component of endometriosis.

Association of WNT4 polymorphisms with endometriosis in infertile patients

PURPOSE

Recently, several genome-wide association studies have demonstrated an association between endometriosis and markers located in or near to WNT4 gene. In order to assess the validity of the findings, we conducted a replication case-control study in a Brazilian population.

METHODS

Genetic association study comprising 400 infertile women with endometriosis and 400 fertile women as controls. TaqMan allelic discrimination technique was used to investigate the relationship between endometriosis and four single-nucleotide polymorphisms (rs16826658, rs3820282, rs2235529, and rs7521902) in WNT4 gene. Genotype distribution, allele frequency, and haplotype analysis of the WNT4 polymorphisms were performed. A p value <0.05 was considered significant.

RESULTS

The results revealed a significant association of rs16826658 (p = 7e-04) and rs3820282 (p = 0.048) single-nucleotide polymorphisms (SNPs) on WNT4 gene with endometriosis-related infertility, while rs2235529 and rs7521902 SNPs showed no difference between cases and controls.

CONCLUSIONS

Our results suggested that rs16826658 and rs3820282 polymorphisms on WNT4 gene might be involved in the pathogenesis of endometriosis in the infertile women studied. Analysis of WNT4 genetic variants might help to identify patients at high risk for disease development.

Genetic variants underlying risk of endometriosis: insights from meta-analysis of eight genome-wide association and replication datasets

BACKGROUND

Endometriosis is a heritable common gynaecological condition influenced by multiple genetic and environmental factors. Genome-wide association studies (GWASs) have proved successful in identifying common genetic variants of moderate effects for various complex diseases. To date, eight GWAS and replication studies from multiple populations have been published on endometriosis. In this review, we investigate the consistency and heterogeneity of the results across all the studies and their implications for an improved understanding of the aetiology of the condition.

METHODS

Meta-analyses were conducted on four GWASs and four replication studies including a total of 11 506 cases and 32 678 controls, and on the subset of studies that investigated associations for revised American Fertility Society (rAFS) Stage III/IV including 2859 cases. The datasets included 9039 cases and 27 343 controls of European (Australia, Belgium, Italy, UK, USA) and 2467 cases and 5335 controls of Japanese ancestry. Fixed and Han and Elkin random-effects models, and heterogeneity statistics (Cochran's Q test), were used to investigate the evidence of the nine reported genome-wide significant loci across datasets and populations.

RESULTS

Meta-analysis showed that seven out of nine loci had consistent directions of effect across studies and populations, and six out of nine remained genome-wide significant (P < 5 × 10⁻⁸), including rs12700667 on 7p15.2 (P = 1.6 × 10⁻⁹), rs7521902 near WNT4 (P = 1.8 × 10⁻¹⁵), rs10859871 near VEZT (P = 4.7 × 10⁻¹⁵), rs1537377 near CDKN2B-AS1 (P = 1.5 × 10⁻⁸), rs7739264 near ID4 (P = 6.2 × 10⁻¹⁰) and rs13394619 in GREB1 (P = 4.5 × 10⁻⁸). In addition to the six loci, two showed borderline genome-wide significant associations with Stage III/IV endometriosis, including rs1250248 in FN1 (P = 8 × 10⁻⁸) and rs4141819 on 2p14 (P = 9.2 × 10⁻⁸). Two independent inter-genic loci, rs4141819 and rs6734792 on chromosome 2, showed significant evidence of heterogeneity across datasets (P < 0.005). Eight of the nine loci had stronger effect sizes among Stage III/IV cases, implying that they are likely to be implicated in the development of moderate to severe, or ovarian, disease. While three out of nine loci were inter-genic, the remaining were in or near genes with known functions of biological relevance to endometriosis, varying from roles in developmental pathways to cellular growth/carcinogenesis.

CONCLUSIONS

Our meta-analysis shows remarkable consistency in endometriosis GWAS results across studies, with little evidence of population-based heterogeneity. They also show that the phenotypic classifications used in GWAS to date have been limited. Stronger associations with Stage III/IV disease observed for most loci emphasize the importance for future studies to include detailed sub-phenotype information. Functional studies in relevant tissues are needed to understand the effect of the variants on downstream biological pathways.

Factors associated with the laterality of recurrent endometriomas after conservative surgery

We evaluated the laterality of primary endometrioma and characteristics of patients according to the laterality of recurrent endometrioma in 140 women with recurrent endometrioma after conservative surgery. Histologically confirmed recurrent endometriomas were found on the left side in 49 patients (35.0%), the right in 44 (31.4%) and bilaterally in 47 (33.6%). The sites of primary endometrioma were not associated with those of recurrent endometrioma, and the recurrence rate in the treated ovary (59.8%) was similar to that of the intact ovary (69.0%) at the primary surgery. Proportions of stage IV endometriosis and posterior cul-de-sac obliteration were higher in patients with bilateral recurrence than in those with unilateral recurrence (p < 0.01 for all comparisons) and in patients with contralateral recurrence than in those with ipsilateral recurrence (p < 0.05 for all comparisons), but no differences were found in other characteristics of participants according to the laterality or pattern of recurrence. In conclusion, the lateral distribution of recurrent endometrioma was not associated with that of the primary lesion, and endometrioma did not recur more frequently in the treated ovary. An advanced stage and the presence of posterior cul-de-sac obliteration were factors associated with bilateral or contralateral recurrence of endometrioma.

Insights into Assessing the Genetics of Endometriosis

Endometriosis is a complex disease arising from the interplay between multiple genetic and environmental factors. The genetic variants potentially underlying the hereditary component of endometriosis have been widely investigated through hypothesis-driven candidate gene studies, an approach that generally has proven to be inherently difficult and problematic for a number of reasons. Recently, through major collaborative efforts in the endometriosis research field, hypothesis-free genome-wide approaches have started to provide new insights into potential pathways leading to development of endometriosis, as well as highlighting the phenotypic heterogeneity of the condition. This review summarizes the most recent studies investigating the genetic variation contributing to endometriosis, with a particular focus on genome-wide approaches, and discusses promising future directions of genetic research.

Epithelial to mesenchymal transition-like and mesenchymal to epithelial transition-like processes might be involved in the pathogenesis of pelvic endometriosis

BACKGROUND

Endometrium is derived from intermediate mesoderm via mesenchymal to epithelial transition (MET) during development of the urogenital system. By retaining some imprint of their mesenchymal origin, endometrial epithelial cells may be particularly prone to return to this state, via epithelial to mesenchymal transition (EMT). We hypothesized that pelvic endometriosis originates from retrograde menstruation of endometrial tissue and that EMT-like and MET-like processes might be involved in the pathogenesis of pelvic endometriosis.

METHODS

We investigated commonly used molecular markers for EMT, including cytokeratin, E-cadherin, N-cadherin, vimentin, S100A4 and dephosphorylated beta-catenin by immunohistochemistry in different forms of pelvic endometriosis: deep infiltrating endometriosis, ovarian endometriosis and superficial peritoneal endometriosis (red and black lesions), as well as samples of menstrual endometrium, other benign ovarian cysts (mucinous and serous cyst adenoma), and abdominal scar endometriosis for comparison.

RESULTS

Epithelial cells of red peritoneal lesions and ovarian endometriosis showed less epithelial marker (cytokeratin, P < 0.0001) expression and more mesenchymal marker (vimentin and/or S100A4, P < 0.0001) expression than those of menstrual endometrium. In contrast, epithelial cells of black peritoneal lesions and deep infiltrating endometriosis showed more epithelial marker (E-cadherin) expression than those of menstrual endometrium (P < 0.03), red peritoneal lesions (P < 0.0001) and ovarian endometriosis (P< 0.0001), but maintained expression of some mesenchymal markers (vimentin, S100A4). In addition, dephosphorylated beta-catenin protein expression was significantly higher in epithelial cells of deep infiltrating endometriosis (P < 0.0001) than in epithelial cells of red and black peritoneal lesions and ovarian endometriosis.

CONCLUSIONS

EMT-like and MET-like processes might be involved in the pathogenesis of pelvic endometriosis.

Advances in the genetics of endometriosis

Endometriosis is a gynecological disease characterized by implantation of endometrial tissue outside of the uterus. Early familial aggregation and twin studies noted a higher risk of endometriosis among relatives. Studies on the roles of the environment, genetics and aberrant regulation in the endometrium and endometriotic lesions of women with endometriosis suggest that endometriosis arises from the interplay between genetic variants and environmental factors. Elucidating the hereditary component has proven difficult because multiple genes seem to produce a susceptibility to developing endometriosis. Molecular techniques, including linkage and genome-wide analysis, have identified candidate genes located near known loci related to development and regulation of the female reproductive tract. As new candidate genes are discovered and hereditary pathways identified using technologies such as genome-wide analysis, the possibility of prevention and treatment becomes more tangible for millions of women affected by endometriosis. Here, we discuss the advances of genetic research in endometriosis and describe technologies that have contributed to the current understanding of the genetic variability in endometriosis, variability that includes regulatory polymorphisms in key genes.

A genome-wide association study identifies genetic variants in the CDKN2BAS locus associated with endometriosis in Japanese

Although the pathogenesis of endometriosis is not well understood, genetic factors have been considered to have critical roles in its etiology. Through a genome-wide association study and a replication study using a total of 1,907 Japanese individuals with endometriosis (cases) and 5,292 controls, we identified a significant association of endometriosis with rs10965235 (P = 5.57 x 10(-12), odds ratio = 1.44), which is located in CDKN2BAS on chromosome 9p21, encoding the cyclin-dependent kinase inhibitor 2B antisense RNA. By fine mapping, the SNP showing the strongest association was located in intron 16 of CDKN2BAS and was implicated in regulating the expression of p15, p16 and p14. A SNP, rs16826658, in the LD block including WNT4 on chromosome 1p36, which is considered to play an important role in the development of the female genital tract, revealed a possible association with endometriosis (P = 1.66 x 10(-6), odds ratio = 1.20). Our findings suggest that these regions are new susceptibility loci for endometriosis.

Differential expression of claudins in human endometrium and endometriosis

Membrane proteins of the claudin superfamily are important components of cellular tight and adherens junctions. Although their exact function remains unclear, these proteins may play a role in tissue remodeling, a process which is associated with several diseases including endometriosis. In the present work we analyzed the expression of 13 members of the claudin family in the endometrium and peritoneum by microarray analysis. Real-time polymerase chain reaction and immunohistochemistry in human endometrium and peritoneal endometriotic lesions were performed for validation of the expression of claudin-1, -3, -4, -5 and -7. Diminished expression of claudin-3, -4 and -7 in ectopic endometrium was frequently observed as indicated by all three methods. In contrast to a higher expression of claudin-5 mRNA detected in bulk biopsies of ectopic endometrium, immunohistochemistry revealed no alteration of claudin-5 protein expression in glandular cells of endometriosis samples. The downregulation of various members of the claudin family may contribute to endometrial cell detachment and increase the number of cells invading pelvic organs.

Expression of membrane-type 5 matrix metalloproteinase in human endometrium and endometriosis

BACKGROUND

The metalloproteinases (MMPs) are a family of proteolytic enzymes involved in tissue remodeling and cell migration. Endometrial tissue remodeling proceeds during the menstrual cycle and requires a temporary and spatially balanced expression of several different MMPs. Various members of the MMPs also seem to play an important role in the invasion process of endometriosis; however, so far only a limited number of studies have focused on membrane-associated MMPs.

METHODS

The present study investigated the expression of membrane-type 5 metalloproteinase (MT5-MMP) in the human endometrium and endometriotic lesions by microarray hybridization, real-time polymerase chain reaction (PCR) and immunofluorescence.

RESULTS

Both the gene chip expression analyses as well as PCR indicated expression of MT5-MMP in normal human endometrium and strongly elevated transcript levels in most peritoneal endometriosis lesions analyzed. Moreover we detected enhanced MT5-MMP expression in the eutopic endometrium from patients suffering from endometriosis, further supporting a role of MT5-MMP in the formation of endometriosis. Immunohistochemical analysis was used to determine the intracellular localization and tissue distribution of MT5-MMP. While the MT5-MMP antigen expression could be clearly attributed to the membrane of epithelial cells, a highly complex differential immunohistochemical staining of MT5-MMP in the various compartments of endometrial tissue was observed. The strongest staining was seen in luminal epithelial cells, whereas endometrial glands frequently showed partial expression of MT5-MMP.

CONCLUSION

Our microarray analysis and real-time PCR of MT5-MMP transcripts may point to an elevated tissue remodeling and cell migration in endometrium from endometriosis patients as implied by the function of related MMPs.