Intestinal Flora and Myocarditis: Potential Mechanisms and Therapeutic Strategies Affecting Disease Progression and Cardiac Function

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  Figure 1. Model of gut–heart axis hypothesis. Gut microbiota is involved in the pathogenesis of cardiovascular diseases via direct or indirect mechanisms. Gut microbiota-associated pathologies (GMAPs), such as gut hyperpermeability, facilitate the translocation of microbial cell wall components (e.g., LPS, peptidoglycans), which act as microbe-associated molecular patterns (MAMPs) and engage pattern recognition receptors (PRRs) to modulate host immune, inflammatory, and metabolic responses. Short-chain fatty acids (SCFAs) exert protective effects through G protein-coupled receptor (GPCR) activation, histone deacetylase (HDAC) inhibition, transporter modulation, and enhancement of the gut barrier. Bile acids (BAs) contribute to lipid emulsification, microbial transformation, nuclear receptor activation (e.g., FXR, VDR, PXR), and GPCR signaling. Trimethylamine (TMA) and its derivative trimethylamine N-oxide (TMAO) promote vascular damage, immune dysregulation, inflammation, and plaque formation, ultimately contributing to cardiovascular events. Additional gut microbiota metabolites, including indoxyl sulfate (IS) and p-cresyl glucuronide (PAGIn), further exacerbate cardiovascular risk. This…

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  Figure 2. Potential mechanisms of gut microbiota involvement in the development of myocarditis. The gut microbiota contributes to myocarditis pathogenesis by compromising intestinal barrier integrity and producing microbiota-derived metabolites. These metabolites modulate disease progression through five interconnected mechanisms: regulating inflammatory responses, mediating immune imbalance, disrupting cardiac energy metabolism and inducing oxidative stress, promoting cardiomyocyte hypertrophy and fibrotic remodeling, and inducing cardiomyocyte apoptosis. Arrows indicate the direction of change (↑: increase/upregulation; ↓: decrease/downregulation). Figure 2 was generated using Microsoft PowerPoint (version 12.1.0.26375).

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  Figure 3. Strategies for modulating gut microbiota to improve cardiovascular diseases. The primary interventional strategies for modulating gut microbiota to improve cardiovascular diseases include fecal microbiota transplantation (FMT); probiotics, prebiotics, synbiotics, and postbiotics (PPSP); dietary modulation; drugs; genetically engineered bacteria; and other therapeutic approaches, such as inhibitors targeting key enzymes involved in microbiota-derived metabolite production. Figure 3 was generated using Microsoft PowerPoint.