Cerebral microvascular endothelial cell-derived extracellular vesicles regulate blood - brain barrier function.

Area of Science:

• Neuroimmunology
• Vascular Biology
• Extracellular Vesicles Research

Background:

• Autoreactive T cells breaching the blood-brain barrier (BBB) drive multiple sclerosis (MS) pathology.
• Extracellular vesicles (EVs) from BBB endothelial cells (BBB-ECs) mediate cell communication and cerebrovascular dysfunction.
• The specific roles of different BBB-EV subpopulations in early MS are not well understood.

Purpose of the Study:

• To investigate the content and function of distinct BBB-EV subpopulations.
• To determine their role in regulating BBB integrity and T cell migration in vitro and in vivo.

Main Methods:

• Characterization of small EVs (sEVs) and large EVs (lEVs) based on size (30-150 nm and 150-300 nm, respectively).
• Analysis of cytokine and adhesion marker expression in BBB-EV subsets.
• In vitro assessment of BBB integrity and T cell transendothelial migration.
• In vivo studies using experimental autoimmune encephalomyelitis (EAE) models in mice.

Main Results:

• BBB-ECs release distinct sEV and lEV populations, with increased sEV secretion during inflammation.
• lEVs significantly impair BBB integrity and promote pro-inflammatory T cell migration (Th1, Th17.1).
• sEVs protect BBB function by promoting an anti-inflammatory phenotype in BBB-ECs.
• In vivo, sEV administration reduced EAE severity, while lEV administration exacerbated it.

Conclusions:

• BBB-EV subpopulations exert opposing effects on BBB integrity and T cell migration.
• sEVs demonstrate potential protective roles, while lEVs contribute to MS pathogenesis.
• These findings highlight the diagnostic and therapeutic potential of targeting BBB-EVs in MS.