S1 Data -

The current COVID-19 mRNA vaccines were developed and applied for pandemic-emergent conditions. These vaccines use a small piece of the virus’s genetic material (mRNA) to stimulate an immune response against COVID-19. However, their potential effects on individuals with chronic inflammatory conditions and vaccination routes remain questionable. Therefore, we investigated the effects of mRNA vaccines in a mouse model of chronic inflammation, focusing on their cardiac toxicity and immunogenicity dependent on the injection route. mRNA vaccine intravenous administration with or without chronic inflammation exacerbated cardiac pericarditis and myocarditis; immunization induced mild inflammation and inflammatory cytokine IL-1beta and IL-6 production in the heart. Further, IV mRNA vaccination induced cardiac damage in LPS chronic inflammation, particularly serum troponin I (TnI), which dramatically increased. IV vaccine administration may induce more cardiotoxicity in chronic inflammation. These findings highlight the need for further research to understand the underlying mechanisms of mRNA vaccines with chronic inflammatory conditions dependent on injection routes.