Proteomic Analysis of rTg-DI Rat Capillaries Reveals Novel Vascular Molecular Targets of Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is a prevalent cerebral small vessel disease (CSVD) and prominent cause of vascular contributions to cognitive impairments and dementia (VCID). CAA is characterized by progressive accumulation of fibrillar amyloid β in cerebral vessel walls, leading to vascular wall degeneration, thrombotic occlusions, microbleeds, and perivascular inflammation causing cognitive deficits. Underlying mechanisms of CAA progression are poorly understood, and there exist no validated diagnostic biomarkers or therapeutic targets for CAA. Here, we performed proteomic mass spectrometry analysis of whole brain tissue and cerebral microvessel enriched fractions from the rTg-DI rat, a validated and well-characterized preclinical rat model of CAA, to identify potential targets and diagnostic markers related to vasculopathy progression in CAA. There were 92 increased and 104 decreased proteins identified in the rTg-DI whole brain samples, while 29 proteins were identified as increased in the enriched cerebral microvessel fractions. We identified several significant differentially expressed proteins in both sample types with commonly elevated proteins including HTRA1, APOE, APOD, CLU, MDK, and LAP3. This study also confirmed the differential expression of several proteins previously reported in isolated brain regions of rTg-DI rats, including ANXA3, APOD, APOE, CLU, CST3, CTSS, CTSD, CTSZ, GFAP, GSTA3, HTRA1, and ITGB2, with APOE, CLU, HTRA1, and GPC1 all reported in human CAA cases. We thus provide a “high-confidence” list of potential marker candidates from proteomic analysis in the rTg-DI rat model of capillary CAA type-1.