Myd88 and Sqstm1 as novel biomarkers for pyroptosis-driven immune checkpoint inhibitors-related myocarditis

BACKGROUND: Among the adverse effects of immunotherapy in cancer patients, immune checkpoint inhibitors (ICIs)-induced myocarditis is the most severe. Pyroptosis is involved in the pathogenesis of various cardiovascular diseases; however, its relationship with ICIs-related myocarditis remains unclear. OBJECTIVE: The purpose of this research is to characterize the critical genes mediating pyroptosis in myocarditis related to ICIs, with the goal of informing clinical practice. MATERIALS AND METHODS: Based on single-cell RNA sequencing and bulk RNA sequencing, this study identified pyroptosis key genes in ICIs-related myocarditis and validated their expression levels and diagnostic value. Single-cell level validation of key genes, trajectory analysis and cellular interactions were also performed. Finally, ICIs-related myocarditis mouse model was established to verify the expression levels of key genes and pyroptosis-related markers. RESULTS: Integration of multiple bioinformatic analyses identified two pyroptosis key genes in ICIs-related myocarditis: Myd88 and Sqstm1. The expression levels of pyroptosis key genes were significantly higher in the ICIs-related myocarditis group compared to the normal group (P < 0.05 or P < 0.01), and both demonstrated high diagnostic value. Trajectory analysis and cell interaction analysis revealed the interaction strength and relative expression patterns between these two pyroptosis key genes. In the ICIs-related myocarditis mouse model, cardiac injury markers were significantly elevated (P < 0.001 or P < 0.0001), while cardiac function indices were significantly decreased (P < 0.01) compared to the normal group. Quantitative real time polymerase chain reaction and western blot analyses revealed that the expression levels of Myd88 and Sqstm1 were significantly upregulated in the myocarditis group compared to the normal group, at both the mRNA and protein expression levels (P < 0.05 or P < 0.01 or P < 0.0001). Compared with the normal group, the expression levels of pyroptosis-related markers Caspase-1, IL-1β, and GSDMD-N were significantly elevated in the myocarditis group (P < 0.05 or P < 0.01). CONCLUSION: Pyroptosis is involved in the pathogenesis of ICIs-related myocarditis, and Myd88 and Sqstm1 may serve as potential biomarkers for future clinical application.