Abstract 16844: Increased Circulating Levels of MiRNA-21 Mirrors Disease Activity in Rats With Monocrotaline-Induced Pulmonary Arterial Hypertension
BACKGROUND: MicroRNAs (miRNAs) are short non-coding RNA molecules that control gene expression by guiding the degradation or translational inhibition of cognate mRNA targets. To date, a small number of miRNAs have been linked to pulmonary arterial hypertension (PAH), and these studies have focused on their intracellular roles. In contrast, extracellular miRNAs that circulate in the blood have not been studied in experimental PAH. These plasma miRNAs may reflect underlying disease activity, and hold promise as non-invasive biomarkers.
HYPOTHESIS: Alterations in plasma miRNAs provide insight into disease activity in PAH.
METHODS AND RESULTS: Eight male Fischer rats were each given a single IP injection of monocrotaline (MCT; 70 mg/kg), and blood and tissue were collected 22 days later (including 8 control rats). Both RVSP (61 ± 5 mm Hg, MCT; 28 ± 1 mm Hg, Con; p<0.0005) and RV/(LV+S) ratio (0.31 ± 0.01, MCT; 0.22 ± 0.01, Con; p<0.0001) were significantly increased at end-study. PCR arrays were used to conduct an unbiased screen of 370 miRNAs from total RNA extracted from plasma, and miRNA levels were normalized with a mean-centering restricted approach. Twenty-five miRNAs were altered in the plasma of MCT rats versus controls, including 10 down and 15 up in MCT rats (from -1.8 to 1.9 fold, p<0.05). Several miRNAs with prior links to PAH were detectable in plasma including miR-21, which was increased in MCT rats (1.4 fold up, p=0.0007). MiR-21 was also significantly upregulated in the lung (3.4 fold, p<0.0001) and kidney (1.4 fold, p<0.05) of MCT rats, while no significant differences were observed in the right ventricle, spleen or liver. Both plasma and lung miR-21 levels were directly correlated with RVSP (r=0.54, p=0.03 and r=0.79, p=0.0003, respectively) and RV/(LV+S) ratio (r=0.56, p=0.02 and r=0.84, p<0.0001, respectively). In plasma, miR-21 becomes susceptible to degradation by endogenous RNases after treatment with proteinase K, but not triton X-100, consistent with a mechanism of stabilization mediated primarily by protein complexation rather than vesicular encapsulation.
CONCLUSIONS: This study establishes novel links between circulating miRNAs and experimental PAH, and supports their potential utility to report underlying disease activity.
- © 2013 by American Heart Association, Inc.