Polarized Desmosome and Hemidesmosome Shedding via Exosomes is an Early Indicator of Outer Blood-Retina Barrier Dysfunction

ABSTRACT: The retinal pigmented epithelium (RPE) makes up the outer blood-retinal barrier, supports photoreceptor function of the eye and is constantly damaged by oxidative stress. Dysfunction of the RPE underlies pathology leading to development of age-related macular degeneration (AMD), the leading cause of vision loss among the elderly in industrialized nations. A major function of the RPE is to process photoreceptor outer segments which relies on the proper functioning of the RPE endocytic pathways and endosomal trafficking. RPE-released exosomes and other extracellular vesicles are essential parts of these pathways and may be early indicators of cellular stress. To test this, we used a polarized primary RPE cell culture model under chronic subtoxic oxidative stress to study the role of exosomes in the extracellular matrix (ECM) changes that underlie the early and late stages of AMD. Resulting unbiased proteomic analyses of highly purified basolateral exosomes from oxidatively stressed RPE cultures revealed changes to proteins involved in epithelial barrier integrity, that were detectable prior to overt cellular dysfunction. There were also changes to proteins accumulating in the basal-side sub-RPE ECM during oxidative stress, that could be prevented in the presence of an inhibitor of exosome release. We show for the first time that chronic subtoxic oxidative stress in primary RPE cultures induces proteomic changes in exosomes including basal-side specific desmosome and hemidesmosome shedding via exosomes. We also show that release of these exosomes correlates with ECM changes that can be partially prevented by inhibition of exosome release. These findings open a completely novel avenue for therapeutic intervention and access to early biomarkers of cellular dysfunction in aging-related retinal diseases, in particular AMD, and broadly from blood-CNS barriers in other neurodegenerative diseases.

INSTRUMENT(S): OrbiTrap Exactive Q HF

ORGANISM(S): Sus Scrofa (ncbitaxon:9823) Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Mikael Klingeborn  

PROVIDER: MSV000092372 | MassIVE | Fri Jul 07 09:13:00 BST 2023

REPOSITORIES: MassIVE