Abstract
Purpose :
Exosomes, small extracellular vesicles enclosed by a lipid bilayer, are present in the aqueous humor (AH) and play a role in intercellular communication, regulating biological processes. MicroRNAs (miRNAs) within exosomes, notably stable in AH, may modulate gene expression in ocular tissues, including the trabecular meshwork (TM). In this study, we investigated the exosomal miRNA profile in the AH of patients with primary open-angle glaucoma (POAG) and exfoliative glaucoma (XFG) and validated the role of individual miRNA in changes in TM cells.
Methods :
Exosomes were isolated and pooled from AH samples of 14 healthy controls, 21 POAG patients, and 24 XFG patients using the precipitation method. Exosomes were confirmed by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and flow cytometry (FC). Exosomal miRNAs were analyzed by small-RNA sequencing. The role of individual miRNAs was validated in human TM (hTM) cells.
Results :
Age did not significantly differ among groups. Exosomes in AH were confirmed by TEM, and CD9, CD63, and CD81 expression were validated through FC. In small-RNA sequencing, distinct microRNA clusters that were differentiated from the normal group were identified in both the POAG and XFG groups. In particular, several down-regulated miRNAs were commonly identified in the glaucoma groups compared to the normal group. Functional analysis identified alterations in miRNAs associated with TM cell fibrosis and extracellular matrix (ECM) remodeling, linked to TGF-beta signaling, Hippo signaling, actin cytoskeleton, and ECM organization in the glaucoma group. Among these, miR-375, which was significantly downregulated in POAG, was linked to the Hippo signaling pathway. Dexamethasone treatment reduced miR-375 expression in hTM cells, and a miR-375 inhibitor activated Hippo signaling, leading to increased expression of connective tissue growth factor (CTGF).
Conclusions :
Significant changes in miRNA content were observed in the AH exosomes in patients with POAG and XFG. Altered miRNA content in the AH exosomes of POAG and XFG patients may impact trabecular meshwork cells via cell-to-cell communication, providing insights into potential targets for glaucoma treatment.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.