Abstract A094: Circulating Proteins and microRNAs in E4FAD Mice and Humans as Biomarkers of Cerebral Microbleeds

Introduction: Cerebral microbleeds (CMBs) are age-related manifestations of microangiopathies, predisposing patients to stroke and cognitive dysfunction. Current imaging standards for CMB diagnosis show low sensitivity and specificity and future CMB sequelae often involve brain regions uninvolved by the lesions. Thus, CMBs are indicators of broader brain disease, and early detection of processes associated with CMBs may identify patients at higher risk of future neurological sequelae. This study assesses circulating proteins and miRNAs in patients and E4FAD mice with CMBs compared to non-CMB controls. Methods: The plasma miRNome was assessed in 6 E4FAD mice and 10 CMB patients and in age and sex matched controls. Putative targets for differently expressed (DE) miRNAs were identified in the respective CMB transcriptomes (p<0.05, FDR corrected). In addition, levels of 10 proteins mechanistically linked to CMBs were quantified in 13 CMB patients and 15 healthy age and sex matched control subjects. Proteins alone and weighted combinations were assessed to differentiate CMB patients from controls using Elastic Net feature selection. Sensitivity and specificity, as well as AUC and confidence interval were calculated for each protein and model. Results: Eighteen DE miRNAs (p<0.1, FDR corrected) were identified in the plasma of E4FAD mice, with 13 having miRNA-mRNA interactions within the E4FAD mouse CMB transcriptome (p<0.05, FDR corrected). These interactions resulted in 58 enriched IPA pathways. Thirty-one DE miRNAs (p<0.1, FDR corrected) were identified in the plasma of human CMB subjects. Of these, 24 had miRNA-mRNA interactions within the human CMB transcriptome (p<0.05, FDR corrected), with 298 enriched pathways. Of interest, miR-150-5p and miR-26a-5p , were dysregulated in both human CMB patients and E4FAD mice (p<0.1, FDR corrected). Protein feature selection identified Aβ-40, CRP, TNFR2, NfL, IL-18, sE-selectin, and GFAP as the best proteins to distinguish CMB human patients, with the combination of Aβ-40 and GFAP performing better than any individual molecule (AUC=73.33%; CI: 54.2% - 92.4%, p<0.05). Conclusion: This is the first report to address miRNAs and circulating proteins in both E4FAD mice and humans with CMBs. Future studies shall aim to validate these discoveries in independent cohorts, explore potential differences in CMBs with hypertensive or amyloid angiopathies, and potentially link these biomarkers to disease severity and prognosis.