Integrated Eutopic Endometrium and Non‐Depleted Serum Quantitative Proteomic Analysis Identifies Candidate Serological Markers of Endometriosis

Background: Endometriosis affects about 4% of women in the reproductive age and is associated with subfertility. The aim of the present study was to examine the quantitative proteomic profile of eutopic endometrium and serum from women with endometriosis compared to controls in order to identify candidate disease-specific serological markers. Methods: Eutopic endometrium and serum from patients with endometriosis (n=8 for tissue and n=4 for serum) was respectively compared to endometrium and serum from females without endometriosis (n=8 for tissue and n=4 for serum) using a shotgun quantitative proteomics method. All study participants were at the proliferative phase of their menstrual cycle. Results: At the tissue and serum level, 1,214 and 404 proteins were differentially expressed (DEPs) in eutopic endometrium and serum respectively of women with endometriosis vs. control. Gene ontology analysis showed that terms related to immune response | inflammation, cell adhesion | migration and blood coagulation were significantly enriched in the DEPs of eutopic endometrium as well as serum. Twenty-one DEPs had the same trend of differential expression in both matrices and can be further examined as potential disease- and tissue-specific serological markers of endometriosis. Conclusions: The present in-depth proteomic profiling of eutopic endometrium and serum from women with endometriosis identified promising serological markers that can be further validated in larger cohorts for the minimally invasive diagnosis of endometriosis.