A Novel Circulating MicroRNA for the Detection of Acute Myocarditis.

The diagnosis of acute myocarditis typically requires either endomyocardial biopsy (which is invasive) or cardiovascular magnetic resonance imaging (which is not universally available). Additional approaches to diagnosis are desirable. We sought to identify a novel microRNA for the diagnosis of acute myocarditis. To identify a microRNA specific for myocarditis, we performed microRNA microarray analyses and quantitative polymerase-chain-reaction (qPCR) assays in sorted CD4+ T cells and type 17 helper T (Th17) cells after inducing experimental autoimmune myocarditis or myocardial infarction in mice. We also performed qPCR in samples from coxsackievirus-induced myocarditis in mice. We then identified the human homologue for this microRNA and compared its expression in plasma obtained from patients with acute myocarditis with the expression in various controls. We confirmed that Th17 cells, which are characterized by the production of interleukin-17, are a characteristic feature of myocardial injury in the acute phase of myocarditis. The microRNA mmu-miR-721 was synthesized by Th17 cells and was present in the plasma of mice with acute autoimmune or viral myocarditis but not in those with acute myocardial infarction. The human homologue, designated hsa-miR-Chr8:96, was identified in four independent cohorts of patients with myocarditis. The area under the receiver-operating-characteristic curve for this novel microRNA for distinguishing patients with acute myocarditis from those with myocardial infarction was 0.927 (95% confidence interval, 0.879 to 0.975). The microRNA retained its diagnostic value in models after adjustment for age, sex, ejection fraction, and serum troponin level. After identifying a novel microRNA in mice and humans with myocarditis, we found that the human homologue (hsa-miR-Chr8:96) could be used to distinguish patients with myocarditis from those with myocardial infarction. (Funded by the Spanish Ministry of Science and Innovation and others.).Supported by a grant (PI19/00545, to Dr. Martín) from the Ministry of Science and Innovation through the Carlos III Institute of Health–Fondo de Investigación Sanitaria; by a grant from the Biomedical Research Networking Center on Cardiovascular Diseases (to Drs. Martín, Sánchez-Madrid, and Ibáñez); by grants (S2017/BMD-3671-INFLAMUNE-CM, to Drs. Martín and Sánchez-Madrid; and S2017/BMD-3867-RENIM-CM, to Dr. Ibáñez) from Comunidad de Madrid; by a grant (20152330 31, to Drs. Martín, Sánchez-Madrid, and Alfonso) from Fundació La Marató de TV3; by grants (ERC-2011-AdG 294340-GENTRIS, to Dr. Sánchez-Madrid; and ERC-2018-CoG 819775-MATRIX, to Dr. Ibáñez) from the European Research Council; by grants (SAF2017-82886R, to Dr. Sánchez-Madrid; RETOS2019-107332RB-I00, to Dr. Ibáñez; and SAF2017-90604-REDT-NurCaMeIn and RTI2018-095928-BI00, to Dr. Ricote) from the Ministry of Science and Innovation; by Fondo Europeo de Desarrollo Regional (FEDER); and by a 2016 Leonardo Grant for Researchers and Cultural Creators from the BBVA Foundation to Dr. Martín. The National Center for Cardiovascular Research (CNIC) is supported by the Carlos III Institute of Health, the Ministry of Science and Innovation, the Pro CNIC Foundation, and by a Severo Ochoa Center of Excellence grant (SEV-2015-0505). Mr. Blanco-Domínguez is supported by a grant (FPU16/02780) from the Formación de Profesorado Universitario program of the Spanish Ministry of Education, Culture, and Sports. Ms. Linillos-Pradillo is supported by a fellowship (PEJD-2016/BMD-2789) from Fondo de Garantía de Empleo Juvenil de Comunidad de Madrid. Dr. Relaño is supported by a grant (BES-2015-072625) from Contratos Predoctorales Severo Ochoa para la Formación de Doctores of the Ministry of Economy and Competitiveness. Dr. Alonso-Herranz is supported by a fellowship from La Caixa–CNIC. Dr. Caforio is supported by Budget Integrato per la Ricerca dei Dipartimenti BIRD-2019 from Università di Padova. Dr. Das is supported by grants (UG3 TR002878 and R35 HL150807) from the National Institutes of Health and the American Heart Association through its Strategically Focused Research Networks.S