Extracellular vesicle-mediated bidirectional communication between macrophages and lesions in the peritoneal microenvironment of endometriosis

Thesis

Endometriosis is characterised by the growth of endometrium like tissue outside the uterus (lesions). Small extracellular vesicles (sEV) in the peritoneal microenvironment of endometriosis modulate intracellular communication and disease progression. This study aimed to characterize the cellular origins of sEV, examine their potential as biomarkers, and investigate their functional role in disease progression by affecting macrophage phagocytic activity.

Using MACSPlex EV flow cytometry and Nanoparticle Tracking Analysis (NTA), the size, concentration, and surface epitopes of sEV from peritoneal fluid (PF), in vitro cultured peritoneal macrophages (pMΦ), and endometrial/lesion derived epithelial organoids (EEO) were characterised.

Flow cytometry revealed distinct sEV profiles from different cellular origins: CD14 and HLA-DR on pMΦ -sEV, and EpCAM and CD133/1 on EEO-sEV. EEO-sEV from lesions expressed higher levels of CD44 and CD29 compared to EEO-sEV from eutopic endometrium. High expression of HLA-DR, EpCAM, and CD133/1 in PF-sEV indicated a predominance of epithelial derived and pMΦ -sEV. Hormonal treatment (HT) was associated with lower EpCAM and higher CD24 expression on PF-sEV. However, no differences were found between endometriosis and control patients. NTA showed lower PF-sEV concentration in HT compared to non-HT. EEO polarity also affected EV size and concentration. Functional analysis revealed impairment of macrophage phagocytic activity (assays using pH-sensitive pHrodo E.coli bioparticles) by PF-sEV and lesion EEO-sEV, mediated through the CD47/SIRP-alpha.

This study revealed the complexity of sEV profiles predominantly from antigen-presenting cells and endometrial epithelial cells. While sEV profiles were distinct from different sources and reflected environmental changes like HT, their use as biomarkers requires further investigation. The functional roles of EV in disease progression potentially extend beyond impairing macrophage phagocytosis as demonstrated in this study, as these sEV expressed various functionally important markers.

Authors: Wang, Y

• DOI: 10.5287/ora-xqgykeb5j
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: endometriosis; peritoneal fluid; macrophage; extracellular vesicles; endometrial epithelial organoids; phagocytosis
• Subjects: Endometriosis; Endometrium