Circulating miRNAs Associated with Frailty in Old People with Cardiovascular Diseases Promote Cellular Senescence and Inflammation

Methods

Leveraging a cohort recruited for a randomized trial testing the effect a remote rehabilitation intervention on frailty in elderlies with cardiovascular diseases (CVD), we tested plasma samples from 24 people, 12 frail and 12 not frail according to the EFT scale and matched for all the other clinical characteristics, to search for miRNAs associated with frailty through small RNA-Sequencing. From this analysis, we selected the 11 most significantly deregulated miRNAs and quantified them in the entire cohort (n=197) through quantitative RT-PCR.

Then, we explored the candidate pathways targeted by miRNAs significantly deregulated in frailty through bioinformatics analyses and tested the effect of miR-181b-3p and miR-490-5p overexpression on cellular senescence and inflammation in endothelial cells. Results: We found that plasma levels of miR-181b-3p, miR-490-5p, and miR-500a-5p were increased, while miR-511-5p was reduced, in people with frailty compared with non-frail individuals, also after adjustment for age.

Bioinformatics analysis of the frailty-upregulated miRNAs suggested cell cycle and cellular response to DNA damage, two recognized drivers of aging, as regulated biological processes for both miR-181b-3p and miR-490-5p. Overexpression of these two miRNAs through transient transfection in endothelial cells promoted a prototypical cellular senescence response accompanied by a pro-inflammatory phenotype, as assessed through SA-Beta Gal staining and increased expression of multiple senescence and inflammatory markers at both mRNA and protein levels.

Conclusions: Overall, these data suggest that circulating levels of miR-181b-3p, miR-490-5p, miR-500a-5p and miR-511-5p might serve as markers of frailty in old people with CVD and that miR-181b-3p and miR-490-5p might be functionally linked to the etiopathogenesis of the syndrome through their effects on cellular senescence and inflammation.