Proteome Profiling of Brain Vessels in a Mouse Model of Cerebrovascular Pathology

Simple Summary We used genetically modified mice overexpressing the cytokine transforming growth factor beta 1 (TGF mice) that capture several aspects of the cerebrovascular pathology present in Alzheimer's disease and vascular cognitive impairment and dementia. To identify the proteins that demonstrated different levels in TGF mice compared to genetically unmodified mice, we performed mass spectrometry on surgically removed cerebral arteries to identify and compare proteins between the two groups. Out of the 3602 identified proteins in brain blood vessels, 20 had significantly different levels in TGF mice. We used multiple public databases to (a) characterize the identified proteins, (b) validate the presence of their RNA transcripts in cerebrovascular cells of mice and humans, and (c) validate their presence in extracellular vesicles (i.e., little pouches of cellular content that participate in cell-to-cell communication) present in human blood. Finally, using human blood, we demonstrated the presence of several of these proteins in blood and in extracellular vesicles isolated from blood. Our research provides protein-level insights into cerebrovascular pathology in age-related dementias. Identified proteins can potentially serve as markers of vascular cognitive impairment and dementia in humans.Abstract Cerebrovascular pathology that involves altered protein levels (or signaling) of the transforming growth factor beta (TGF beta) family has been associated with various forms of age-related dementias, including Alzheimer disease (AD) and vascular cognitive impairment and dementia (VCID). Transgenic mice overexpressing TGF beta 1 in the brain (TGF mice) recapitulate VCID-associated cerebrovascular pathology and develop cognitive deficits in old age or when submitted to comorbid cardiovascular risk factors for dementia. We characterized the cerebrovascular proteome of TGF mice using mass spectrometry (MS)-based quantitative proteomics. Cerebral arteries were surgically removed from 6-month-old-TGF and wild-type mice, and proteins were extracted and analyzed by gel-free nanoLC-MS/MS. We identified 3602 proteins in brain vessels, with 20 demonstrating significantly altered levels in TGF mice. For total and/or differentially expressed proteins (p <= 0.01, >= 2-fold change), using multiple databases, we (a) performed protein characterization, (b) demonstrated the presence of their RNA transcripts in both mouse and human cerebrovascular cells, and (c) demonstrated that several of these proteins were present in human extracellular vesicles (EVs) circulating in blood. Finally, using human plasma, we demonstrated the presence of several of these proteins in plasma and plasma EVs. Dysregulated proteins point to perturbed brain vessel vasomotricity, remodeling, and inflammation. Given that blood-isolated EVs are novel, attractive, and a minimally invasive biomarker discovery platform for age-related dementias, several proteins identified in this study can potentially serve as VCID markers in humans.