Abstract
Purpose :
Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment in the elderly. Emerging evidence suggests extracellular vesicles (EVs), such as exosomes and microvesicles, participate in the pathogenesis of AMD. EVs released by all cells contain lipids, proteins, and nucleic acids. The cargo of EVs is related to the nature and physiology of their cell of origin and any change in cell homeostasis might modify their molecular composition. EVs can travel through different biofluids (i.e., blood, tears, saliva). The purpose of this study was to investigate the cargo contained in plasma-derived EVs in patients with different phenotypes of AMD and to specifically characterize the proteome and transcriptome cargo which has not been previously described
Methods :
40 patients enrolled in the University of Colorado AMD Registry were used in the study. AMD phenotypes were determined using multimodal imaging. Plasma from 10 control (CT), 10 intermediate AMD (iAMD), 10 Geographic Atrophy (GA), and 10 Neovascular (NV) AMD patients was used to study EVs. We isolated EVs using size exclusion chromatography. We characterized vesicle morphology, molecular composition, size, and distribution by electron microscopy (TEM), immunoblotting, and Nanosight (NTA). Finally, EV cargo was characterized by proteomic and transcriptomic analysis
Results :
We observed typical rounded membrane vesicles within a size range of 30–170 nm. The physical characteristics of the vesicle preparations and their biochemical composition (presence of Syntenin, and absence of GM130) confirmed that they fulfilled the criteria for EVs. EVs isolated from the plasma of patients with intermediate AMD and late AMD (NV and GA) had different protein and RNA profiles than those of CT group. Furthermore, proteomic profiling of plasma-derived EV cargo revealed that EVs were enriched in proteins related to the complement and the immune system
Conclusions :
This study represents the first description of the transcriptomic and proteomic profile from EV released in plasma from AMD patients. Our results are aligned with the findings of other investigators who have shown that that EVs reflect intracellular changes that occur in response to pathological conditions. Assessing EV biomarkers in circulating extracellular vesicles could be a powerful non-invasive approach to monitor AMD disease progression
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.