Non-invasive diagnosis of endometriosis: Immunologic and genetic markers

Exosomal miR-21-5p derived from endometrial stromal cells promotes angiogenesis by targeting TIMP3 in ovarian endometrial cysts

Endometriosis is a multifactorial gynecological disease, with angiogenesis as a key hallmark. The role of exosomal microRNAs (miRNAs) in endometriosis is not well understood. This study investigates differentially expressed exosomal miRNAs linked to angiogenesis in endometriosis, clarifies their molecular mechanisms, and identifies potential targets. Primary endometrial stromal cells (ESCs) were cultured, and exosomes were extracted. In a co-culture system, ESC-derived exosomes were taken up by human umbilical vein endothelial cells (HUVECs). Endometriosis implant-ESC-derived exosomes (EI-EXOs) significantly promoted HUVEC proliferation, migration and tube formation compared to normal endometrium-exosomes (NE-EXOs), a finding consistent in vivo in mice. MiRNA sequencing and bioinformatics identified differentially expressed miR-21-5p from EI-EXOs, confirmed by RT-qPCR. The miR-21-5p inhibitor or GW4869 attenuated EI-EXO-induced HUVEC proliferation, migration, and tube formation. TIMP3 overexpression diminished the pro-angiogenic effect of EI-EXOs, which was reversed by adding EI-EXOs or upregulating miR-21-5p. These findings validate the crosstalk between ESCs and HUVECs mediated by exosomal miR-21-5p, and confirm the miR-21-5p-TIMP3 axis in promoting angiogenesis in endometriosis. KEY MESSAGES: ESC-derived exosomes were found to be taken up by recipient cells, i.e. HUVECs. Functionally, endometriosis implant-ESC-derived exosomes (EI-EXOs) could significantly promote the proliferation, migration and tube formation of HUVECs compared to normal endometrium-exosomes (NE-EXOs). Through miRNA sequencing and bioinformatics analysis, differentially expressed miR-21-5p released by EI-EXOs was chosen, as confirmed by qRT-PCR. miR-21-5p inhibitor or GW4869 was found to attenuate the proliferation, migration, and tube formation of HUVECs induced by EI-EXOs. In turn, TIMP3 overexpression diminished the pro-angiogenic effect of EI-EXOs, and this angiogenic phenotype was reversed once EI-EXOs were added or miR-21-5p was upregulated.

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.

Serum Metabolites as Diagnostic Biomarkers in Patients with Endometriosis

Endometriosis diagnosis is usually delayed. The gold standard for diagnosing endometriosis is laparoscopy, which is invasive and accompanied by several risks. Currently, there are no effective non-invasive biomarkers for diagnosing endometriosis. Here, we investigated whether metabolites whose levels are altered in patients with endometriosis hold potential as diagnostic biomarkers for the disease. This case-control study involved 32 patients with endometriosis and 29 patients with other benign gynecological disease. The diagnosis of all patients was confirmed through postoperative histopathological examination, and the patients were divided into two groups: an endometriosis group (EM) and a control group. Fasting blood was collected and used for non-targeted metabolomic-based detection. The data were processed through principal component analysis, orthogonal partial least squares discriminant analysis, and significance analysis of microarrays. A univariate receiver operating characteristic curve was used to evaluate the diagnostic value of the metabolites. The metabolite profiles of patients with endometriosis were markedly different compared with those of the controls. In addition, several metabolic pathways, including biosynthesis of unsaturated fatty acids, arginine biosynthesis, and glutathione metabolism, were altered. Ornithine and medorinone showed better potential as biomarkers for endometriosis diagnosis than CA125. We analyzed the altered metabolic profiles in patients with endometriosis and found ornithine and medorinone as potential non-invasive biomarkers for endometriosis diagnosis, whereas the combined ornithine-medorinone diagnosis is more valuable. These findings may help advance research on non-invasive diagnostic biomarkers for endometriosis. Further research with an improved study design and a larger cohort should be performed to confirm the diagnostic potential and clinical application of these biomarkers.

Determination of Serum Arginase-1 Concentrations and Serum Arginase Activity for the Non-Invasive Diagnosis of Endometriosis

Backgroud: Endometriosis remains a diagnostic challenge, both clinically and economically, affecting 6% to 15% of women of child-bearing potential. We have attempted to determine whether testing serum concentrations and activity of arginase isoenzymes could be useful for the non-invasive diagnosis of endometriosis. Methods: This study involved 180 women (105 endometriosis subjects-study group B; 22 subjects with other benign gynaecological conditions-control group 1-K1, both undergoing surgery; and 53 healthy subjects without features of endometriosis-control group 2-K2). Results: Preoperative and postoperative arginase-1 (Arg-1) concentrations were significantly higher in patients, as compared with the control groups K1 (p < 0.0001 and p = 0.0005, respectively) and K2 (both p < 0.0001). Similarly, arginase activity was significantly higher in patients than in the control group K1 before surgery and higher than in both control groups after surgery. No significant differences in either Arg-1 concentrations or arginase activity were noted between the operated control group K1 and the non-operated control group K2. A significant postoperative decrease in Arg-1 concentration was observed within both patient (p < 0.0001) and control group K1 (p = 0.0043). Diagnostic performance was assessed using the receiver operating characteristic (ROC) method. The threshold for differentiation between endometriosis patients and healthy non-operated controls was 42.3 ng/mL, with a sensitivity of 90% and specificity of 81%. For differentiation of patients and operated controls with benign gynaecological conditions, the threshold was 78.4 ng/mL, with a sensitivity of 61% and specificity of 95%. Conclusions: We, therefore, conclude that Arg-1 serum concentrations and arginase activity could be considered potential biomarkers for endometriosis but require further studies on larger cohorts of patients.

Identification of miR-30c-5p microRNA in Serum as a Candidate Biomarker to Diagnose Endometriosis

The diagnosis of endometriosis by laparoscopy is delayed until advanced stages. In recent years, microRNAs have emerged as novel biomarkers for different diseases. These molecules are small non-coding RNA sequences involved in the regulation of gene expression and can be detected in peripheral blood. Our aim was to identify candidate serum microRNAs associated with endometriosis and their role as minimally invasive biomarkers. Serum samples were obtained from 159 women, of whom 77 were diagnosed with endometriosis by laparoscopy and 82 were healthy women. First, a preliminary study identified 29 differentially expressed microRNAs between the two study groups. Next, nine of the differentially expressed microRNAs in the preliminary analysis were evaluated in a new cohort of 67 women with endometriosis and 72 healthy women. Upon validation by quantitative real-time PCR technique, the circulating level of miR-30c-5p was significantly higher in the endometriosis group compared with the healthy women group. The area under the curve value of miR-30c-5p was 0.8437, demonstrating its diagnostic potential even when serum samples registered an acceptable limit of hemolysis. Dysregulation of this microRNA was associated with molecular pathways related to cancer and neuronal processes. We concluded that miR-30c-5p is a potential minimally invasive biomarker of endometriosis, with higher expression in the group of women with endometriosis diagnosed by laparoscopy.

Role of cystatin C levels as an inflammatory marker in predicting endometriosis

OBJECTIVE

Endometriosis is a common chronic inflammatory disease associated with infertility and pelvic pain. Diagnosis is based on the appearance of endometriotic lesions at the time of surgery. Our study aimed to determine whether cystatin C can be used as a predictor of endometriosis and to investigate its potential role in doing so.

METHODS

The study included 45 patients with endometriosis between the ages of 18 and 40 years whose pathology results were compatible with endometriosis and were operated on, and a control group of 45 healthy women. These two groups were compared in terms of serum cystatin C levels, demographic-clinical characteristics, operation results, and other laboratory values.

RESULTS

The cystatin C and hs-CRP levels of the endometriosis patients were found to be significantly higher than the control subjects (p<0.005). Whether the endometriosis disease could be detected for serum cystatin C levels was determined by the receiver operating characteristic analysis and the most appropriate positive cutoff value for cystatin C was found to be 5.14 ng/mL (86.7% sensitivity and 77.8% specificity). In the linear regression analysis, it was observed that the probability of endometriosis increased 2.5 times when cystatin C levels increased above the threshold value of 5.14 ng/mL (OR: 2.5; 95%CI 2.24-2.76).

CONCLUSION

Our study shows that the serum cystatin C levels can be used as a guide for diagnosis in patients with advanced endometriosis. However, more research is needed to prove its reliability and accuracy in order to put it into practice.

The Presence of Pre-Existing Endometriotic Lesions Promotes the Growth of New Lesions in the Peritoneal Cavity

Endometriosis is a common gynecological disease which is characterized by endometriotic lesions outside the uterine cavity. In this study, we investigated whether the presence of pre-existing endometriotic lesions promotes the development of new lesions due to the exchange of cells and an altered peritoneal environment. For this purpose, uterine tissue samples from FVB/N wild-type donor mice were transplanted simultaneously or time-delayed with samples from transgenic FVB-Tg(CAG-luc-GFP)L2G85Chco/J donor mice into the abdominal cavity of FVB/N wild-type recipient mice. The formation of endometriotic lesions was analyzed by means of high-resolution ultrasound, bioluminescence imaging, histology and immunohistochemistry. Moreover, immune cells and inflammatory factors in the peritoneal fluid were assessed by flow cytometry and a cytokine array. These analyses revealed that the growth of newly developing endometriotic lesions is promoted by the presence of pre-existing ones. This is not due to an exchange of cells between both lesion types but rather caused by peritoneal inflammation induced by already established lesions. These findings indicate that, among other pathogenic mechanisms, the chronic nature of endometriosis may be driven by a lesion-induced inflammatory milieu in the peritoneal cavity, which creates favorable conditions for the development of new lesions.

Possible Correlation between Urocortin 1 (Ucn1) and Immune Parameters in Patients with Endometriosis

The etiology of endometriosis (EMS) has not been clearly elucidated yet, and that is probably the reason why its diagnostic process is frequently long-lasting and inefficient. Nowadays, the non-invasive diagnostic methods of EMS are still being sought. Our study aimed to assess the serum and peritoneal fluid levels of urocortin 1 (Ucn1) in patients with EMS and healthy women. Moreover, considering the immune background of the disease, the association between Ucn1 and several immune parameters was studied in both groups. We found that the serum Ucn1 level was significantly upregulated in women with EMS compared to healthy patients. Moreover, higher serum Ucn1 levels tended to correspond with more advanced stages of the disease (p = 0.031). Receiver operating characteristic (ROC) analysis revealed that based on serum Ucn1 levels, it is possible to distinguish deep infiltrating endometriosis (DIE) from among other EMS types. Together, these results indicate Ucn1 as a possible promising biomarker of EMS: however, not in isolation, but rather to enhance the effectiveness of other diagnostic methods.

The Association between Deoxyribonucleic Acid Hypermethylation in Intron VII and Human Leukocyte Antigen-C∗07 Expression in Patients with Endometriosis

OBJECTIVE

Endometriosis, which is a common disease affecting approximately 10% of women of reproductive age, usually causes dysmenorrhea and infertility, thus seriously harming the patients' physical and mental health. However, there is a mean delay of 6.7 years between the onset of the symptoms and the surgical diagnosis of endometriosis. There is an increasing amount of evidence that suggests that epigenetic aberrations, including deoxyribonucleic acid (DNA) methylation, play a definite role in the pathogenesis of endometriosis. This study aimed to explore the noninvasive or minimally invasive biomarkers of this disease.

MATERIALS AND METHODS

Six patients with surgically confirmed ovarian endometriosis and six patients who received IUD implantation for contraception without endometriosis were recruited in the East Hospital of Tongji University in 2018. The genome methylation profiling of the eutopic and ectopic endometrium of ovarian endometriosis patients and normal endometrial specimens from healthy women was determined using a methylation microarray test. The test screened methylation-differentiated 5'-C-phosphate-G-3' (CpG) sites and then located the target genes affected by these sites following sequence alignment. Then, an additional 22 patients and 26 healthy controls were enrolled to further verify the difference in the selected genes between endometriosis patients and healthy women. The differential DNA methylation of the selected genes was validated via direct bisulfite sequencing and analysis of their messenger ribonucleic acid (mRNA) levels using quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

Fifteen differentially methylated CpG sites were found among the patients and healthy women, and five CpG sites were mapped to the introns of the human leukocyte antigen-C (HLA-C) gene; these were highly polymorphic between different HLA-C alleles and were HLA-C∗07 specific. The results indicated that the HLA-C∗07 carrier patients exhibited significantly higher DNA methylation levels at the intron VII of HLA-C compared to the HLA-C∗07 carrier healthy controls. High HLA-C∗07 mRNA levels were also observed using qRT-PCR with HLA-C∗07-specific primers, which indicated that the hypermethylation of CpG in intron VII might suppress a silencer that regulates HLA-C∗07 expressions.

CONCLUSION

Deoxyribonucleic acid hypermethylation in the intron VII of the HLA-C∗07 gene appears to regulate the expression of HLA-C∗07. The aberrant DNA methylation in this region was positively correlated with the occurrence of endometriosis.