The role of miRNAs in viral myocarditis, and its possible implication in induction of mRNA-based COVID-19 vaccines-induced myocarditis.

Background: Several reports of unheeded complications secondary to the current mass international rollout of SARS-COV-2 vaccines, one of which is myocarditis occurring with the FDA fully approved vaccine, Pfizer, and others. Main body of the abstract: Certain miRNAs (non-coding RNA sequences) are involved in the pathogenesis in viral myocarditis, and those miRNAs are interestingly upregulated in severe COVID-19. We hypothesize that the use of mRNA-based vaccines may be triggering the release of host miRNAs or that trigger the occurrence of myocarditis. This is based on the finding of altered host miRNA expression promoting virus-induced myocarditis. Short conclusion: In conclusion, miRNAs are likely implicated in myocarditis associated with mRNA vaccines. Our hypothesis suggests the use of miRNA as a biomarker for the diagnosis of mRNA vaccine-induced myocarditis. Additionally, the interplay between viral miRNA and the host immune system could alter inflammatory profiles, hence suggesting the use of therapeutic inhibition to prevent such complications.

Possible molecular and paracrine involvement underlying the pathogenesis of COVID-19 cardiovascular complications.

Coronavirus disease 2019 (COVID-19) has been declared a pandemic on 11 March 2020 by the WHO. Despite being mainly a respiratory virus, cardiac complications have been described. These range from sudden cardiac death to subtle diastolic dysfunction after recovery from COVID-19. The commonest cardiac presentation to date is acute heart failure resulting from biventricular or left ventricular hypokinesis and elevation of cardiac troponins. It has been shown that COVID-19 downregulates angiotensin-converting enzyme-2, which has protective effects on the endothelium and cardiomyocytes. It has also been proven that COVID-19 induces a state of hypercytokinaemia, some cytokines such as interleukin-1 and interleukin-6 have an injurious effect on the myocardium and endothelium, respectively. Such pathogenic mechanisms might play a crucial role in induction of cardiomyocyte injury and impaired myocardial perfusion probably through coronary endothelial dysfunction. The understanding and linking of such mechanisms might help in tailoring drug repurposing for treatment or prophylaxis of COVID-19 cardiovascular complications.