Circulating microRNAs, Vascular Risk, and Physical Activity in Spinal Cord-Injured Subjects

The aim of this study was to compare the expression of serum microRNAs (miRNAs) in individuals with spinal cord injury (SCI) (athletes [SCI-A] and sedentary [SCI-S]) and able-bodied (AB) individuals, and investigate the relationship of miRNAs with carotid intima-media thickness (cIMT) and serum oxidized LDL-cholesterol (oxLDL) among SCI subjects. Seventeen SCI-S, 23 SCI-A, and 22 AB males were evaluated by clinical and laboratory analysis, and had oxLDL and cIMT measured by enzyme-linked immunosorbent assay (ELISA) and ultrasonography, respectively. A total of 754 miRNAs were measured using a TaqMan OpenArray^® Human MicroRNA system. SCI-S subjects had higher cIMT and oxLDL than SCI-A and AB. Compared with AB, only one miRNA was differently expressed in both SCI-A and SCI-S individuals, whereas 25 miRNAs were differently expressed in SCI-S, but not in SCI-A. Of these 25 miRNAs, 22 showed different expression between SCI-S and SCI-A. Several miRNAs correlated with oxLDL and cIMT among all SCI individuals. Notably, miR-125b-5p, miR-146a-5p, miR-328-3p, miR-191-5p, miR-103a-3p, and miR-30b-5p correlated with both oxLDL and cIMT, and showed distinct expression between the SCI-A and SCI-S groups. Gene set enrichment analysis demonstrated that miRNAs related to cIMT and oxLDL may be involved in molecular pathways regulating vascular function and remodeling. In conclusion, this exploratory analysis suggests that variations in circulating miRNA expression in individuals with SCI compared with AB subjects are markedly attenuated by regular physical activity. Several miRNAs may be involved in physical activity-related improvements in vascular risk and remodeling among SCI individuals.