Circulating proteomic profiles associated with endometriosis in adolescents and young adults

Abstract

Study question: What are the systemic molecular profiles of endometriosis diagnosed in adolescents and young adults?

Summary answer: Significant enrichment and increased activation of proteins related to angiogenesis and cell migration pathways were observed in endometriosis cases compared to controls (P-value < 2.4 × 10-8).

What is known already: Little is known about the pathophysiology of adolescent endometriosis despite the fact that over 50% of adults with endometriosis report onset of severe pelvic pain during adolescence.

Study design, size, duration: A cross-sectional analysis using data on 142 laparoscopically confirmed endometriosis cases and 74 controls from the observational longitudinal cohort of Women's Health Study: From Adolescence to Adulthood (A2A).

Participants/materials, setting, methods: We measured 1305 plasma protein levels using the validated, multiplex aptamer-based proteomics discovery platform, SOMAscan. We calculated odds ratios and 95% CIs using logistic regression adjusting for age, BMI, fasting status and hormone use at blood draw for differentially expressed proteins (P < 0.05). Ingenuity Pathway Analysis and STRING analysis were performed to identify biological pathways and protein interactions. We also examined proteins and pathways associated with superficial peritoneal lesion colors (i.e. red, vascularized, white, blue/black, brown).

Main results and the role of chance: Average age at blood draw was 18 years for endometriosis cases and 22 years for controls. We identified 63 proteins associated with endometriosis with type-I error set at 0.05, and absolute fold change >1.2, revealing significant enrichment of dysregulated proteins in biological pathways associated with endometriosis. Increased activation of pathways related to angiogenesis and cell migration was observed in plasma from endometriosis cases compared to controls (P-value < 2.4 × 10-8). Furthermore, when we examined proteins and pathways associated with lesion colors, vascularized lesions were associated with upregulation of pathways related to immune cell migration/activation and inflammation, whereas white, blue/black and brown lesions were associated with downregulation of these pathways.

Limitations, reasons for caution: Validation of our results in independent datasets and mechanistic studies are warranted to further our understanding of the pathophysiological characteristics of this common but understudied patient population.

Wider implications of the findings: To our knowledge, this was the first study to comprehensively examine circulating proteins in predominantly adolescents and young adult women with and without endometriosis. Results from this study provide novel biological insight that will build toward further research to elucidate endometriosis pathophysiology during the earlier course of the disease trajectory.

Study funding/competing interest(s): This study was supported by the Department of Defense (W81XWH1910318) and the 2017 Boston Center for Endometriosis Trainee Award. Financial support for establishment of and data collection within the A2A cohort were provided by the J. Willard and Alice S. Marriott Foundation. N.S., A.F.V., S.A.M., K.L.T. have received funding from Marriott Family Foundation. S.A.M. and K.L.T. are supported by NICHD (R01 HD94842). S.A.M. serves as an advisory board member for AbbVie and Roche; neither are related to this study. The authors report no conflict of interest.

Trial registration number: N/A.

Keywords: adolescents; angiogenesis; endometriosis; lesion color; proteomics.

Figure 1.

Pathways associated with endometriosis based on 63 proteins with P-value <0.05 and absolute fold-change >1.2 in the A2A cohort (n = 216). Biological pathways associated with endometriosis are grouped by the direction of association (i.e. activation z-score) and presented within group ordered by P-value. Upregulated pathways are denoted by red bubbles and downregulated pathways are denoted by blue bubbles. Of the top 20 statistically significant pathways, two pathways (morphology of bone and uveitis pathways) were removed due to activation z-score of 0.0.

Figure 2.

STRING analysis and visualization of protein–protein interaction clusters (k-means = 6 clusters indicated by node color) and relevant pathways associated with endometriosis in the A2A cohort (n = 216). Protein–protein interaction network was created based on the 63 proteins that were significantly associated with endometriosis with unadjusted P-value <0.05 and absolute fold-change >1.2. Related functional categories are labeled based on proteins with their reported functional involvement in the pathways of angiogenesis (red node), cell migration (light green node), inflammation (dark green node), oxidative stress response (purple node) and neurogenesis (yellow node). Solid line represents within-cluster, dashed gray line represents between-cluster interactions. Line thickness indicates strength of data support. Red box indicates major hub nodes.

Figure 3.

Venn diagram showing unique and overlapping proteins by lesion colors among endometriosis cases in the A2A cohort (n = 142). There were 40 proteins associated with having any red lesions (red circle), 40 proteins associated with having any white lesions (black circle), 32 proteins associated with having any blue/black lesions (light blue circle), 39 proteins associated with having any brown lesions (brown circle) and 47 proteins associated with having any vascularized lesions (yellow circle), with unadjusted P-value <0.05. Entrez gene symbols of proteins that overlapped between two or more lesion colors are presented.

Figure 4.

Top pathways associated with lesion colors in the A2A cohort (n = 142). Biologic pathways associated with each lesion color are presented in the dot chart. Upregulated pathways are denoted by red dots and downregulated pathways are denoted by blue dots. Of the top 20 statistically significant pathways, the following pathways were removed due to activation z-score being equivalent to 0.0: red lesion (uterine serous papillary cancer, fasciculation of axons); white lesion (chronic inflammatory disorder); blue lesion (chronic inflammatory disorder). The pathway names are colored in the following groups: pathways related to cell migration (blue font), pathways related to immune cell movement (pink font), pathways related to immune cell activation (green font), pathways related to inflammation (red font), pathways related to vascularization (purple font) and others (orange font).