AIMS: Coronavirus disease 2019 (COVID-19) can lead to multiorgan damage. MicroRNAs (miRNAs) in blood reflect cell activation and tissue injury. We aimed to determine the association of circulating miRNAs with COVID-19 severity and 28-day intensive care unit (ICU) mortality.
METHODS AND RESULTS: We performed RNA-Seq in plasma of healthy controls (n = 11), non-severe (n = 18) and severe (n = 18) COVID-19 patients and selected 14 miRNAs according to cell- and tissue origin for measurement by reverse transcription quantitative polymerase chain reaction (RT-qPCR) in a separate cohort of mild (n = 6), moderate (n = 39) and severe (n = 16) patients. Candidates were then measured by RT-qPCR in longitudinal samples of ICU COVID-19 patients (n = 240 samples from n = 65 patients). 60 miRNAs, including platelet-, endothelial-, hepatocyte- and cardiomyocyte-derived miRNAs, were differentially expressed depending on severity, with increased miR-133a and reduced miR-122 also being associated with 28-day mortality. We leveraged mass spectrometry-based proteomics data for corresponding protein trajectories. Myocyte-derived (myomiR) miR-133a was inversely associated with neutrophil counts and positively with proteins related to neutrophil degranulation, such as myeloperoxidase. In contrast, levels of hepatocyte-derived miR-122 correlated to liver parameters and to liver-derived positive (inverse association) and negative acute phase proteins (positive association). Finally, we compared miRNAs to established markers of COVID-19 severity and outcome, i.e. SARS-CoV-2 RNAemia, age, BMI, D-dimer and troponin. Whilst RNAemia, age and troponin were better predictors of mortality, miR-133a and miR-122 showed superior classification performance for severity. In binary and triplet combinations, miRNAs improved classification performance of established markers for severity and mortality.
CONCLUSION: Circulating miRNAs of different tissue origin, including several known cardiometabolic biomarkers, rise with COVID-19 severity. MyomiR miR-133a and liver-derived miR-122 also relate to 28-day mortality. MiR-133a reflects inflammation-induced myocyte damage, whilst miR-122 reflects the hepatic acute phase response.
TRANSLATIONAL PERSPECTIVE: Adding biomarkers to conventional scores for illness severity and mortality could improve prognostic performance in COVID-19 patients. Circulating miRNAs are emerging as promising biomarkers with tissue specific origins but have only sparsely been investigated in COVID-19. We quantified circulating miRNAs of different tissue origin in COVID-19 patients, identifying several miRNAs of the cardiometabolic system to be associated with severity. Myocyte-derived miR-133a and liver-derived miR-122 also associated with mortality. Through longitudinal proteomics measurements, we related myomiR miR-133a release to neutrophil activation and miR-122 release to the hepatic acute phase response. Our findings highlight key pathophysiological changes and provide first evidence on the performance of miRNA biomarkers in COVID-19.