Endometriosis: a genetic disease

Novel Drug Targets with Traditional Herbal Medicines for Overcoming Endometriosis

Endometriosis is a disease in which the lining of the endometrium is found outside of the uterus. Recent medical treatments for endometriosis have adverse effects, limiting their long-term use. Furthermore, the recurrence of the disease after the cessation of therapy is quite common, and most patients need to continue treatment to maintain a hypoestrogenic environment till conception. Notwithstanding recent advances in computational and chemical practices, traditional medicines are considered the most consistent sources for the discovery of new drugs. Numerous medicinal plants and plantderived compounds have been tested against gynecological disorders, mainly endometriosis. This review aimed to describe the pharmacological activity profile of the medicinal plants and their active ingredients and draw attention to the discovery of multitargeted drug molecules for rational therapy.

Machine Learning Classifiers for Endometriosis Using Transcriptomics and Methylomics Data

Endometriosis is a complex and common gynecological disorder yet a poorly understood disease affecting about 176 million women worldwide and causing significant impact on their quality of life and economic burden. Neither a definitive clinical symptom nor a minimally invasive diagnostic method is available, thus leading to an average of 4 to 11 years of diagnostic latency. Discovery of relevant biological patterns from microarray expression or next generation sequencing (NGS) data has been advanced over the last several decades by applying various machine learning tools. We performed machine learning analysis using 38 RNA-seq and 80 enrichment-based DNA methylation (MBD-seq) datasets. We experimented how well various supervised machine learning methods such as decision tree, partial least squares discriminant analysis (PLSDA), support vector machine, and random forest perform in classifying endometriosis from the control samples trained on both transcriptomics and methylomics data. The assessment was done from two different perspectives for improving classification performances: a) implication of three different normalization techniques and b) implication of differential analysis using the generalized linear model (GLM). Several candidate biomarker genes were identified by multiple machine learning experiments including NOTCH3, SNAPC2, B4GALNT1, SMAP2, DDB2, GTF3C5, and PTOV1 from the transcriptomics data analysis and TRPM6, RASSF2, TNIP2, RP3-522J7.6, FGD3, and MFSD14B from the methylomics data analysis. We concluded that an appropriate machine learning diagnostic pipeline for endometriosis should use TMM normalization for transcriptomics data, and quantile or voom normalization for methylomics data, GLM for feature space reduction and classification performance maximization.

The impact of infertility diagnosis on embryo-endometrial dialogue

Initial stages of implantation involve bi-directional molecular crosstalk between the blastocyst and endometrium. This study investigated an association between infertility etiologies, specifically advanced maternal age (AMA) and endometriosis, on the embryo-endometrial molecular dialogue prior to implantation. Co-culture experiments were performed with endometrial epithelial cells (EEC) and cryopreserved day 5 blastocysts (n = 41 ≥ Grade 3BB) donated from patients presenting with AMA or endometriosis, compared to fertile donor oocyte controls. Extracellular vesicles isolated from co-culture supernatant were analyzed for miRNA expression and revealed significant alterations correlating to AMA or endometriosis. Specifically, AMA resulted in 16 miRNAs with increased expression (P ≤ 0.05) and strong evidence for negative regulation toward 206 target genes. VEGFA, a known activator of cell adhesion, displayed decreased expression (P ≤ 0.05), validating negative regulation by 4 of these increased miRNAs: miR-126; 150; 29a; 29b (P ≤ 0.05). In endometriosis patients, a total of 10 significantly altered miRNAs displayed increased expression compared to controls (miR-7b; 9; 24; 34b; 106a; 191; 200b; 200c; 342-3p; 484) (P ≤ 0.05), targeting 1014 strong evidence-based genes. Three target genes of miR-106a (CDKN1A, E2F1 and RUNX1) were independently validated. Functional annotation analysis of miRNA-target genes revealed enriched pathways for both infertility etiologies, including disrupted cell cycle regulation and proliferation (P ≤ 0.05). These extracellular vesicle-bound secreted miRNAs are key transcriptional regulators in embryo-endometrial dialogue and may be prospective biomarkers of implantation success. One of the limitations of this study is that it was a stimulated, in vitro model and therefore may not accurately reflect the in-vivo environment.

Association of interleukin-16 polymorphisms with disease progression and susceptibility in endometriosis

Interleukin-16 (IL-16) is a multifunctional pro-inflammatory cytokine that was previously found in association with complex disorders, and it is now cleared that this cytokine plays a critical role in regulation of cellular functions such as homoeostasis. Due to the complexity of endometriosis and its resemblance to cancer, we designed present case-control study to determine the effects of genetic polymorphisms of the human IL-16 gene on Iranian women's susceptibility to endometriosis. A total of 126 patients with endometriosis (stages I-IV) and 144 healthy women as control group were recruited to the study. We genotyped four single nucleotide polymorphisms of IL-16 gene (rs11556218 T>G, rs4778889 T>C, rs4072111 C>T and rs1131445 C>T). Genotyping was performed using PCR and restriction fragment length polymorphism. Our results showed that genotype distribution in two exonic polymorphisms including rs11556218 and rs4072111 was significantly different between Endometriosis patients and healthy individuals (P < 0.05). We have also found an association between rs4072111 and rs1131445 with progression to the severe stages (III-IV) of endometriosis (P < 0.05). Finally, we may conclude that IL-16 gene polymorphisms are highly associated with increased risk of endometriosis and could be considered as a susceptibility factor for endometriosis.

Novel therapies targeting endometriosis

Endometriosis is an often painful disorder in which the endometrial glands and stroma grow outside the uterus. The disease affects women's quality of life and is a common cause of infertility. In this review, we describe promising new developments in the field based on in vitro assays and rodent models, each of which has the potential to be beneficial in the treatment of this disease. We will specifically describe the role of anti-inflammatory drugs, selective estrogen, or progesterone modulators, statins, antiangiogenic agents, and the potential for targeting stem cells as likely methods to hone in and eliminate endometriosis. The most promising of these potential therapies are currently slated for further testing in both rodent and nonhuman primate trials.

Functional genetic polymorphisms and female reproductive disorders: part II--endometriosis

BACKGROUND

Endometriosis has a strong genetic component, and numerous genetic studies have been reported.

METHODS

We have systematically reviewed these studies and included 114 in our final selection.

RESULTS

We found no consistent evidence linking endometriosis with specific polymorphisms in genes encoding inflammatory mediators, proteins involved in sex steroid metabolism, vascular function and tissue remodelling. Although a number of polymorphisms have been associated with endometriosis in selected populations, the associations have not been independently confirmed, either because only single studies were carried out on these markers/genes or because other studies reported no association. The most solid evidence linking specific polymorphisms to endometriosis came from studies investigating glutathione-S-transferase, a phase II detoxification enzyme. Carriage of the GSTT1 null deletion variant showed consistent association with endometriosis with a 29% increased risk; however, it cannot be excluded that this result was due to publication bias, and this association should be independently confirmed in large-scale, well-designed case–control studies.

CONCLUSIONS

The evidence of an association between genetic polymorphisms and endometriosis is weak. Carriage of the GSTT1 null deletion may moderately increase the risk of this disease. We suggest that the methodology of association studies should be improved in order to identify and validate associations in endometriosis.

Endometriosis and tissue factor

Tissue factor (TF), is a cellular receptor that binds the ligand factor VII/VIIa to initiate the blood coagulation cascade. In addition to its role as the initiator of the hemostatic cascade, TF is known to be involved in angiogenesis via an interaction with factor VIIa and protease-activated receptor-2 (PAR-2). In this article we review previous studies from our laboratory demonstrating that the pattern and level of TF expression is altered in multiple cell types derived from eutopic and ectopic endometrium from women with endometriosis compared with normal endometrium. We posit that the inflammatory environment that occurs in ectopic and eutopic endometrium from patients with disease results in high TF expression that in turn, signals via PAR-2 to further produce inflammatory cytokine or chemokine production and macrophage recruitment. Thus, our studies suggest that TF might be an ideal target for therapeutic intervention in endometriosis.

Endometriosis markers: immunologic alterations as diagnostic indicators for endometriosis

Because endometriosis, a chronic disease affecting 7% to 10% of women, is associated with immunologic aberrations, the authors hypothesize that the presence of specific immune alterations may be diagnostic. Autoantibodies were assayed by Western immunoblotting using antigens derived from the plasma membrane, cytosol, and nucleus from endometrial and ovarian cells. Natural killer (NK) activity was defined by levels of signaling protein zeta and induction of interferon (IFN)-gamma following exposure to patients' sera. Patients with endometriosis exhibited autoantibodies reactive with cellular proteins; endometrial membrane proteins exhibited the greatest reactivity, followed by nuclear antigens. In all subcellular fractions, patients with stage 3 endometriosis exhibited significantly more immunoreactivity than did stage 2 patients, which was greater than that observed in stage 1 patients. The stage-associated increased reactivity resulted from both recognition of additional proteins and enhanced reactivity with shared proteins. Patient sera suppressed NK zeta expression, which resulted in suppression of NK IFN induction. Alterations in autoreactivity and NK activity are observed in endometriosis and may be useful as diagnostic markers, even in early stage disease.

An investigation of the effects of endometriosis on the proteome of human eutopic endometrium: A heterogeneous tissue with a complex disease

The pathogenesis of endometriosis includes the proliferation of heterogeneous endometrial cells and their invasion into ectopic sites within the peritoneal cavity. This may be due to abnormalities of the eutopic endometrium itself, predisposing the cells to survive and implant ectopically. We investigated the applicability of 2-DE gels and peptide mass mapping to identify candidate endometrial proteins with a role in endometriosis. Despite the heterogeneous nature of endometrium, our results show that combining the analysis of 2-DE gels and peptide mass mapping yields consistent data. We identified dysregulated proteins in women with endometriosis which included: (i) molecular chaperones including heat shock protein 90 and annexin A2, (ii) proteins involved in cellular redox state, such as peroxiredoxin 2, (iii) proteins involved in protein and DNA formation/breakdown, including ribonucleoside-diphosphate reductase, prohibitin and prolyl 4-hydroxylase, and (iv) secreted proteins, such as apolipoprotein A1. These proteins have functions which suggest that they could play a role in the pathogenesis of endometriosis. This study demonstrated that 2-DE gel analysis and mass spectroscopic protein identification are suitable for the identification of proteins with candidate associations with endometriosis. These techniques should be used on a larger scale to identify endometriosis-related proteins, thus improving the understanding of this complex disease.

Polymorphisms of the vitamin D receptor gene predict the onset of surgical menopause in Caucasian females

We tested association of four single nucleotide polymorphisms (SNPs) of the vitamin D receptor gene (VDR) with age at surgical and natural menopause in a sample of Caucasians composed of 153 women with surgical and 260 with natural menopause. A significant association was observed between age at surgical menopause and two SNPs, rs1544410 (BsmI) and rs731236 (TaqI) (p < 0.05). For rs1544410, homozygotes of the minor allele, AA, had about two-fold higher risk of surgical menopause than homozygotes of the major allele, GG (95% confidence ratio (CI) 1.09-3.82). For rs731236, the CC subjects had a greater chance of surgical menopause than the TT subjects (odds ratio = 2.01, 95% CI 1.07-3.78). Since rs1544410 and rs731236 are in strong linkage disequilibrium, the haplotypes based on these two loci were also tested. The haplotype AC was highly significantly associated with age at surgical menopause (p = 0.008). Women with this haplotype had surgical menopause on average 2.8 years earlier than non-carriers. These results reveal the potential effect of the VDR gene on ovaries and uterus, and suggest that its SNPs can be used as predictors of genetic susceptibility for early surgical menopause and respective causal health problems.

Macrophage migration inhibitory factor expression in the intrauterine endometrium of women with endometriosis varies with disease stage, infertility status, and pelvic pain

OBJECTIVE

To evaluate the concentrations of macrophage migration inhibitory factor (MIF) in the eutopic endometrial tissue of women with and without endometriosis.

DESIGN

Retrospective study using ELISA to measure MIF concentrations in total endometrial tissue proteins extracts.

SETTING

Gynecology clinic and human reproduction research laboratory.

PATIENT(S)

Forty-five women with endometriosis and 25 normal women.

INTERVENTION(S)

Endometrial biopsies were obtained a few days before laparoscopy.

MAIN OUTCOME MEASURE(S)

Concentrations of MIF in tissue protein extracts.

RESULT(S)

Levels of MIF were significantly higher in women with endometriosis, increased with disease stage, and were cycle phase dependent. Of note is the significant increase in MIF levels occurring in the midsecretory phase in women with endometriosis as compared with controls, particularly in infertile patients, as well as in the late secretory phase preceding menstruation. Furthermore, MIF levels seemed to be particularly elevated in women with endometriosis who were infertile and who suffered from pelvic pain.

CONCLUSION(S)

This study showed a significant increase in MIF concentrations in the intrauterine endometrial tissue of women with endometriosis, occurring at specific phases of the menstrual cycle, a relationship between MIF concentrations and disease stage, and a possible role for this factor in endometriosis-associated pain and infertility.

Ten estrogen-related polymorphisms and endometriosis: a study of multiple gene-gene interactions

OBJECTIVE

Genetic as well as hormonal factors are known to influence the development and clinical course of endometriosis. We aimed to investigate the association among 10 single nucleotide polymorphisms (SNPs) involved in the estrogen metabolism and endometriosis and to develop a multiple genetic model.

METHODS

In a case-control study, we investigated the genotype frequencies of 10 estrogen metabolizing SNPs in 32 patients with endometriosis and 790 healthy controls using sequencing-on-chip-technology with solid-phase polymerase chain reaction on oligonucleotide microarrays: catechol-O-methyltransferase, Val158Met G->A, 17-beta-hydroxysteroid dehydrogenase type 1 (HSD17), vlV A->C, cytochrome P450 (CYP), 17 A2 allele T->C, CYP1A1 MspI RFLP T->C, CYP1A1 Ile462Val A->G, CYP19 Arg264Cys C->T, CYP19 C1558T C->T, CYP 1B1 Leu432Val, CYP1B1 Asn453Ser, and estrogen receptor alpha IVS1 -401>C. Associations and 2-way interaction models between SNPs were calculated by stepwise logistic regression models.

RESULTS

In a univariate model, HSD17 vlV A->C was associated with a significantly increased risk of endometriosis (P = .004; odds ratio 3.9, 95% confidence interval 1.6-9.8). When all 2-way interactions of investigated SNPs were ascertained, no significant interactions among SNPs were observed. In a multivariate model, HSD17 vlV A->C was also significantly associated with endometriosis (P = .002).

CONCLUSION

We present data on multiple SNPs in patients with endometriosis indicating an association between HSD17 gene variation and the disease. Although not able to demonstrate interaction models of SNPs, we provide evidence of HSD17 vlV A->C as a low penetrance genetic marker of endometriosis.

LEVEL OF EVIDENCE

II-2.

Evaluation of clinical parameters and estrogen receptor alpha gene polymorphisms for patients with endometriosis

Endometriosis is a chronic inflammatory disease, which is especially found in women with subfertility problems with an incidence of up to 30%. The disease is considered an estrogen-dependent disorder, where DNA polymorphisms of the estrogen receptor α (ERα) in connection with endometriosis are controversially discussed. From a German population of women, clinical data associated with the disease, including the American Fertility Society (AFS) I–IV classification, and non-clinical parameters were evaluated statistically in endometriosis patients (n= 98) and in control women (n= 98) without endometriosis. Using a multivariate statistical analysis, significant associations of endometriosis with dysmenorrhea (P< 0.001) and allergies against medicaments (P= 0.042) were found. A positive trend between first grade family history of endometriosis and allergies against medicaments was also observed, suggesting a genetic relationship. From both collectives, DNA from peripheral blood was analyzed for the frequency of the ERα DNA polymorphisms Xba1 (A/G) and PvuII (T/C) in intron 1 and the ERα exonic DNA polymorphism (G229A) with an amino acid exchange (Gly77Ser) in the transactivation domain. DNA samples from endometriosis lesions and control tissues from the same collectives were also analyzed for the exonic G229A polymorphism. Only homozygote wild-type alleles for the polymorphism G229A were found, making it a rare polymorphism in mid-European individuals. Allele types for the PvuII and Xba1 polymorphisms were analyzed with the observed statistically significant clinical parameters and showed no significant association with endometriosis; however a trend with AFS IV was noted, which could contribute to lesion severity. In conclusion, the analyzed polymorphisms in the ERα do not have a functional role concerning specific clinical parameters associated with endometriosis.

Advances in the management of endometriosis: an update for clinicians

Endometriosis is a chronic and recurrent disease characterized by the presence and proliferation of endometrial tissue outside the uterine cavity, which occurs in approximately 10% of women of reproductive age. In this estrogen-dependent disorder, lesions become inactive and gradually undergo regression during states of ovarian down-regulation, such as amenorrhoea or menopause. The impact of endometriosis includes impaired fertility potential, as well as symptoms of dysmenorrhoea, dyspareunia and chronic non-menstrual pain, all of which adversely affect quality of life. Management of endometriosis focuses on pain relief and includes medical and surgical treatment. Pharmacologic therapies currently in use include combination oral contraceptives (COCs), danazol, GnRH analogues and progestins. Although some agents show efficacy in relieving pain, all differ in their side effects, making it difficult to achieve a balance between efficacy and safety. Efficacy has been demonstrated with danazol or GnRH analogues; however, treatment is limited to 6 months because of significant metabolic side effects. Alternatives for longer-term management of symptoms include add-back therapy with GnRH analogues, COCs or progestins. Newer options for treatment of endometriosis include depot medroxyprogesterone acetate subcutaneous injection, as well as several agents under investigation that may prove to have therapeutic potential.

Myofascial dysfunction in the pelvis

Chronic pelvic pain is a potentially devastating condition that affects many women with severe consequences. A multifaceted condition, chronic pelvic pain enjoys a diverse etiology, a myriad of treatments, and a correspondingly irregular response to therapy. The condition can be associated with severe physical dysfunction in relation to voiding, defecation, and sexual function. Although emphasis has been placed on surgical approaches to therapy, there is increasing interest in alternative therapies, particularly using the principles of the treatment of myofascial dysfunction.