Plasma exosomal proteomics: Unveiling novel biomarkers for ischemic stroke in the context of diabetes

Diabetes elevates the risk of ischemic stroke and poor prognosis. Exosomes, which carry nucleic acids and proteins, transmit stable signals across the blood-brain barrier and serve as promising non-invasive biomarkers for brain injury. Exosome proteomics may thus reveal novel therapeutic strategies to improve outcomes in diabetic stroke patients. Exosomes were isolated from the plasma of acute ischemic stroke patients with and without type 2 diabetes (n = 10 each) and characterized them using electron microscopy, flow cytometry, and nanoparticle tracking analysis. Label-free proteomics and bioinformatics were performed to identify prognostic biomarkers, with mass spectrometry data deposited in ProteomeXchange (PXD068810). CIBERSORTx and BRETIGEA were used to resolve cellular origins, and western blotting was applied to verify key proteins in mouse brain tissue and plasma exosomes after stroke. Diabetic stroke patients showed higher glucose, HbA1c and neutrophils. Proteomics identified 95 differentially expressed proteins mainly involved in oxygen/NO transport, glucose metabolism and oxidative stress. Protein-protein interaction network analysis highlighted HBA1, HBA2, HBB, HBD, PFKL, and ALDH3A2 as key regulators. Western blot confirmed that db/db mice brain exhibited significantly elevated HBA2 and HBB, reduced PFKL expression which correlated with MAP2 at 24 h after reperfusion. Plasma-derived exosomes from db/db mice also showed markedly lower PFKL expression. Diabetes altered exosomal contributions, diminishing signals from CD4 memory T cells and brain endothelial cells, while enhancing those from follicular helper T cells. These findings underscore the potential of exosome-based diagnostics and therapeutics for diabetic stroke, paving the way for innovative therapeutic strategies.