Evaluation of Proteasome and Immunoproteasome Levels in Plasma and Peritoneal Fluid in Patients with Endometriosis

Menstrual blood serum extracellular vesicles reveal novel molecular biomarkers and potential endotypes of unexplained infertility

Several biomolecules have been previously associated with unexplained infertility (uIF) in blood and uterine samples, immune cells and their secreted factors, endometrial tissue, menstrual blood, serum, and stromal cells, however they do not comprehensively represent different uIF endotypes and their isolation/detection involves invasive diagnostic methods and lacks precision. This ex-vivo study was performed on extracellular vesicles (EVs) from menstrual blood collected on cycle day 2 from 9 fertile volunteers and 8 women with uIF. Menstrual blood serum (MBS) EVs were isolated from fertile and uIF MBS using Iodixanol Density Gradient Centrifugation and quantified by flow cytometry. EVs were characterized according to MISEV2023 guidelines. Comprehensive proteomic analysis of MBS EVs and EV-depleted MBS showed significant changes in uIF proteome, mostly affecting cell adhesion, immune response, apoptosis, response to oxidative stress and lipid metabolism. These processes were previously linked to pathologies of the female reproductive system but never investigated in uIF and were used to stratify patients into distinct molecular endotypes. Area under the curve (AUC) analysis was used to determine the optimum set of biomarkers for each of the uIF molecular endotypes. These findings provide new insights into uIF that could facilitate personalised treatment approaches.

Is Osteopontin a Reliable Biomarker for Endometriosis?

This study aimed to evaluate the concentration of osteopontin in peritoneal fluid and plasma as potential biomarkers for diagnosing endometriosis. Osteopontin levels were measured using surface plasmon resonance imaging (SPRI) biosensors in patients suspected of having endometriosis. Plasma samples were collected from 120 patients, and peritoneal fluid was collected from 86 patients. Based on the detection of endometriosis lesions during laparoscopy, participants were divided into a study group (patients with endometriosis) and a control group (patients without endometriosis). The results showed no significant differences in plasma osteopontin levels between women with endometriosis and the control group (19.86 ± 6.72 ng/mL vs. 18.39 ± 4.46 ng/mL, p = 0.15). Similarly, peritoneal fluid osteopontin concentrations did not differ significantly between patients with and without endometriosis (19.04 ± 5.37 ng/mL vs. 17.87 ± 5.13 ng/mL, p = 0.29). Furthermore, osteopontin levels in both plasma and peritoneal fluid were not significantly associated with the stage of endometriosis, the presence of endometrioma, or the menstrual cycle phase. The findings of this study do not support osteopontin concentration as a reliable biomarker for endometriosis. However, further research is necessary to explore osteopontin's potential role in the disease.

Is the leptin/BMI ratio a reliable biomarker for endometriosis?

Background

The aim of this study was to analyze the concentration of leptin in peritoneal fluid and plasma and to assess their role as potential biomarkers in the diagnosis of endometriosis.

Materials & methods

Leptin adjusted for BMI (leptin/BMI ratio) was measured using surface plasmon resonance imaging (SPRI) biosensors. Patients with suspected endometriosis were included in the study. Plasma was collected from 70 cases, and peritoneal fluid from 67 cases. Based on the presence of endometriosis lesions detected during laparoscopy, patients were divided into a study group and a control group (patients without endometriosis).

Results

Leptin/BMI ratio in plasma did not differ between women with endometriosis and the control group (0.7159 ± 0.259 vs 0.6992 ± 0.273, p= 0,7988). No significant differences were observed in peritoneal leptin/BMI ratio levels in patients with and without endometriosis (0.6206 ± 0.258 vs 0.6215 ± 0.264, p= 0,9896). Plasma and peritoneal leptin/BMI ratios were significantly lower in women with endometriosis - related primary infertility compared to women with endometriosis without primary infertility (0.640 ± 0.502 vs 0.878 ± 0.623, p < 0.05). The difference was observed in case of primary infertility, but not in terms of the secondary one. No significant differences were noted between leptin/BMI ratio in the proliferative phase and the secretory phase (0.716 ± 0.252 vs 0.697 ± 0.288, p= 0,7785).

Conclusion

The results of present study do not support the relevance of leptin concentration determination as a biomarker of the endometriosis. Due to the limited number of samples in the tested group, further studies are needed to confirm its role.