Plasma extracellular vesicle miRNAs as potential biomarkers of the transition from compensated cardiac hypertrophy to heart failure in rats

Abstract

Hypertension and cardiac hypertrophy initiate molecular pathways that can result in heart failure (HF). Despite the importance of cardiac hypertrophy as a risk factor for the development of HF, not all hypertrophied hearts will develop HF. Possibly, HF‐prone hearts are molecularly defined in the early stages of the disease, before the transition to HF. HF diagnosis is most often made at an advanced stage of the disease. This determines the need of markers at the earliest possible stage of the disease. Circulating microRNAs have been considered novel candidate biomarkers for HF. The aim of the present study was to identify if plasma extracellular vesicles (EVs) microRNAs could be used as biomarkers during the transition of compensated cardiac hypertrophy to HF in rats submitted to abdominal aorta constriction. Previous published data from our group showed that at 60‐days post‐surgery (dps) there was 2 groups: controls and operated animals with compensated cardiac hypertrophy and preserved systolic function. At 90 dps, the operated group was subdivided into 2 groups: animals with hypertrophic hearts (resistance to heart failure, R‐HF), around 70% of the animals, and animals with hypertrophic + dilated hearts (HF), around 30%. Since at 60 dps there was no difference among operated animals by echocardiography and there is no signal which animal will develop HF, a retrospective study was performed: plasma microRNAs from animals at 90 dps (HF‐90dps and R‐HF‐90dps) were compared to the plasma from the same animals earlier at 60 dps (HF‐60dps and R‐HF‐60dps) to identify possible microRNAs that could be used as early biomarker of HF. Plasma was collected before surgery and at 60 and 90 dps. Ejection fraction (EF) was evaluated by echocardiography. Plasma circulating microparticles concentration and size were characterized by Nanoparticle tracking analysis. Relative levels of 312 rat miRNAs were evaluated by RT‐qPCR at 60 dps. Data were considered significant when p<0.05. There is no difference in the EF among sham (61.85±6.62%), R‐HF‐60dps (59.50±8.05%) and 60dps (62.07±8.91%) and R‐HF‐90dps (56.33±7.76%). There is no difference in the particle concentration among sham (3.24x1011/ml), R‐HF‐60dps (5.48x1011/ml) and HF‐60dps (3.54x1011/ml). The same was seen in relation to particles size: sham (104.98 nm), R‐HF‐60dps (104.88 nm) and HF‐60dps (107.25 nm). The microRNA profiling detected a total of 191 miRNAs present in sham, R‐HF‐60dps and HF‐60dps. Of these, a total of 42 miRNA were upregulated in the group HF‐60dps when compared to R‐HF‐60dps (let‐7b‐5p; let‐7d‐3p; 125a‐5p; 127‐3p; 130a‐3p; 149‐5p; 30d‐5p; 30e‐5p; 31b; 34a‐3p; 423‐5p; 499‐5p; 145‐5p; 146a‐3p; 15a‐3p; 181d‐5p; 182, 185‐5p; 193b‐5p; 211‐5p; 322‐3p; 375‐5p; 351‐5p; 500‐3p; 92b‐3p; 212‐3p; 22‐3p; 21‐5p; 221‐3p; 27b‐3p; 21‐5p; 221‐3p; 27b‐3p; 301a‐3p; 28‐3p; 301b‐3p; 30a‐5p; 486; 423‐3p; 497‐5p; 671 and 99a‐5p). Further studies at 90 dps should be performed. These 41 upregulated miRNAs need to be compared to the miRNA profiling at 90 dps. If any of these miRNAs are still upregulated at 90 dps, the predicted pathways regulated by these miRNAs can be analyzed and these miRNAs could be used as a biomarker of HF in these animals.