MG53 protects against Coxsackievirus B3-induced acute viral myocarditis in mice by inhibiting NLRP3 inflammasome-mediated pyroptosis via the NF-κB signaling pathway.

Pyroptosis, a novel programmed cell death mediated by NOD-like receptor protein 3 (NLRP3) inflammasome, is a critical pathogenic process in acute viral myocarditis (AVMC). Mitsugumin 53 (MG53) is predominantly expressed in myocardial tissues and has been reported to exert cardioprotective effects through multiple pathways. Herein, we aimed to investigate the biological function of MG53 in AVMC and its underlying regulatory mechanism in pyroptosis. BALB/c mice and HL-1 cells were infected with Coxsackievirus B3 (CVB3) to establish animal and cellular models of AVMC. As inflammation progressed in the myocardium, we found a progressive decrease in myocardial MG53 expression, accompanied by a significant enhancement of cardiomyocyte pyroptosis. MG53 overexpression significantly alleviated myocardial inflammation, apoptosis, fibrosis, and mitochondrial damage, thereby improving cardiac dysfunction in AVMC mice. Moreover, MG53 overexpression inhibited NLRP3 inflammasome-mediated pyroptosis, reduced pro-inflammatory cytokines (IL-1ß/18) release, and suppressed NF-κB signaling pathway activation both in vivo and in vitro. Conversely, MG53 knockdown reduced cell viability, facilitated cell pyroptosis, and increased pro-inflammatory cytokines release in CVB3-infected HL-1 cells by promoting NF-κB activation. These effects were partially reversed by applying the NF-κB inhibitor BAY 11-7082. In conclusion, our results suggest that MG53 acts as a negative regulator of NLRP3 inflammasome-mediated pyroptosis in CVB3-induced AVMC, partially by inhibiting the NF-κB signaling pathway. MG53 is a promising candidate for clinical applications in AVMC treatment.

Analysis of long noncoding RNAs and messenger RNAs expression profiles in the hearts of mice with acute viral myocarditis.

Acute viral myocarditis (AVMC) is a common acute myocardial inflammation caused by viral infections, which can lead to severe cardiac dysfunction. Several long noncoding RNAs (lncRNAs) with aberrant expression have been identified in the pathogenesis of AVMC. However, the expression profiles and functions of lncRNAs in AVMC have not been fully elucidated. In the present study, we constructed AVMC mouse models by intraperitoneal injection of coxsackievirus B3 (CVB3) and performed RNA sequencing (RNA-seq) on heart tissues to investigate the differences in lncRNAs and messenger RNAs (mRNAs) expression profiles. Based on the cutoff criteria of adjusted p-values (padj) <0.05 and |log2FoldChange| >1, a total of 1122 differentially expressed lncRNAs (DElncRNAs) and 3186 differentially expressed mRNAs (DEmRNAs) were screened, including 734 upregulated and 388 downregulated lncRNAs, 1821 upregulated and 1365 downregulated mRNAs. RT-qPCR analysis validated that the expression patterns of 12 randomly selected genes (6 DElncRNAs and 6 DEmRNAs) were highly consistent with those in RNA-seq, proving the reliability of the RNA-seq data. Then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that differentially expressed genes were mainly involved in metabolic and immune-related processes. Furthermore, co-expression networks between DElncRNAs and DEmRNAs in cytokine-cytokine receptor interaction, MAPK signaling pathway, and PI3K-Akt signaling pathway were constructed to study the molecular interactions of these molecules. Our study, for the first time, reveals the expression profiles of lncRNAs and mRNAs associated with AVMC, which may shed light on the roles of lncRNAs in disease pathogenesis and aid in discovering new therapeutic targets.

Neutralization of interleukin-38 exacerbates coxsackievirus B3-induced acute myocarditis in mice.

BACKGROUND: Interleukin (IL)-38, a novel member of the IL-1 family, has been reported to be involved in several diseases associated with viral infection. However, the expression and functional role of IL-38 in acute viral myocarditis (AVMC) have not been investigated. METHODS: Male BALB/c mice were treated with intraperitoneal (i.p.) injection of coxsackievirus B3 (CVB3) for establishing AVMC models. On day 7 post-injection, the expression of IL-38 and IL-36R (IL-36 receptor) were measured. Mice were then treated with i.p. injection of mouse Anti-IL-38 Antibodies (Abs) for neutralization of IL-38. The survival, bodyweight loss, cardiac function, and myocarditis severity of mice were recorded. The percentages of splenic Th1 and Th17 cells, the expression levels of Th1/Th17-related master transcription factors (T-bet and RORγt) and cytokines were determined by flow cytometry, RT-qPCR, and ELISA, respectively. Cardiac viral replication was further detected. RESULTS: The mRNA and protein expression levels of IL-38 in myocardium and serum, as well as cardiac IL-36R mRNA levels were significantly elevated in mice with AVMC. Increased IL-38 levels were negatively correlated with the severity of AVMC. Neutralization of IL-38 exacerbated CVB3-induced AVMC, as verified by the lower survival rate, impaired cardiac function, continuous bodyweight loss, and higher values of HW/BW and cardiac pathological scores. In addition, neutralization of IL-38 suppressed Th1 cells differentiation while promoted Th17 cells differentiation, accompanied by decreased T-bet mRNA expression and increased RORγt expression. Down-regulation of IFN-γ and up-regulation of IL-17, TNF-α, and IL-6 mRNA and protein expression levels in myocardium and serum were also observed in the IL-38 neutralization group. Furthermore, neutralization of IL-38 markedly promoted cardiac viral replication. CONCLUSIONS: Neutralization of IL-38 exacerbates CVB3-induced AVMC in mice, which may be attributable to the imbalance of Th1/Th17 cells and increased CVB3 replication. Thus, IL-38 can be considered as a potential therapeutic target for AVMC.