Objectives: Vogt-Koyanagi-Harada syndrome is common autoimmune uveitis that can cause blindness. Recent studies have shown that plasma exosomes carry disease-related proteins that may serve as biomarkers. Here, we aimed to find candidate biomarkers of Vogt-Koyanagi-Harada disease using proteomic analysis of plasma exosomes.
Methods: Exosomes were isolated from the plasma of normal controls and Vogt- Koyanagi-Harada patients in the following groups: a) initial inflammatory attack (active stage), b) remission after one month of treatment (unstable stage), and c) stationary phase after three months of treatment (stable stage). Groups were analyzed by mass spectrometry using isobaric tags for relative and absolute quantitation. After functional analysis, proteins of interest were verified by ELISA.
Results: 463 proteins were identified in the exosomes. Forty-three were upregulated at the active inflammation stage, including inflammation-associated proteins. Thirty-one were downregulated. Gene ontology and pathway analyses revealed differential proteins related to cell adhesion, cell phagocytosis, cytoskeleton movement, leukocyte migration across endothelial cells, and platelet activation. By ELISA, Carbonic anhydrase 2 and Ras-related protein Rap-1b were verified as more plentiful at the active stage compared to the normal control and stationary phase in exosomes, but not, however, in microvesicles or plasma.
Conclusion: Plasma exosomes of Vogt-Koyanagi-Harada patients contain many proteins related to the degree of inflammation. The levels of Carbonic anhydrase 2 and Ras-related protein Rap-1b in exosomes can be used as biomarkers for active inflammation in Vogt-Koyanagi-Harada disease. Further investigation could help study the pathogenesis of Vogt-Koyanagi-Harada disease and identify therapeutic targets.