Abstract 292: Microparticle-encapsulated miRNAs Are Associated With Peripheral Artery Disease

Abstract

miRNAs are short, noncoding RNAs that circulate in plasma within membrane-bound vesicles, such as microparticles (MPs), or bound to proteins or lipoproteins. Circulating miRNAs are putative biomarkers for a wide range of diseases, including cardiovascular disease. Our group and others have evidence to suggest MP-encapsulated miRNAs, rather than total plasma miRNAs, may harbor more specific and functionally relevant biomarkers. We tested the hypothesis that MP-encapsulated miRNA levels would differ between patients with mild or severe peripheral artery disease (PAD) and healthy controls matched for age, gender, and race. Banked plasma stored at -80°C was obtained for 5 healthy subjects, 6 patients with mild PAD (ABI 0.8-1.0), and 10 patients with severe PAD (ABI < 0.4). MPs were isolated using a standard differential centrifugation protocol and quantified by flow cytometry. Four miRNAs implicated in vascular disease (miR-126-3p, miR-126-5p, miR-21, and miR-222) were quantified with qRT-PCR. Relative expression for each miRNA (-2ΔCt) was calculated and divided the total number of MPs to determine miRNA expression per MP. There was a non-significant trend towards increased levels of MPs in patients with mild (19,462 MPs/μl ± 5,213) and severe PAD (21,688 MPs/μl ± 7,175) compared to healthy controls (7244 MPs/μl ± 919). MP levels of miR-126-5p were increased among healthy subjects compared to patients with mild and severe PAD (p = 0.003), while MP miR-126-3p levels were significantly lower in healthy subjects (p = 0.002). miR-21 and miR-222 did not differ significantly between groups. None of the four miRNAs distinguished mild versus severe PAD. In conclusion, our data suggests that MP-mediated transport of miR-126-5p and miR-126-3p is dysregulated in the setting of mild and severe vascular disease, and supports the concept that the plasma MP fraction may harbor disease-associated miRNA profiles.