TCR β CDR3 repertoire remodeling in pediatric myocarditis reveals clonal expansion and disease-associated public clonotypes

Figures

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  Figure 1. Clonal diversity and clonotype distribution of TCR β CDR3 repertoires. (A) D50 index for repertoire diversity analysis between Myo and NC groups; (B) Chao1 estimator for repertoire diversity analysis between Myo and NC groups; (C) Clonotype abundance distribution among small, medium, large and hyperexpanded clones. Myo, pediatric myocarditis; NC, normal control; *p < 0.05, **p < 0.01, ***p < 0.001.

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  Figure 2. V and J gene usage and V–J pairing patterns of TCR β CDR3 repertoires. (A) TRBV gene usage frequencies between Myo and NC groups; (B) TRBJ gene usage frequencies between Myo and NC groups; (C) Representative circos plots of V–J gene pairing from individual samples; (D) Volcano plot of V–J pairing frequencies showing significantly enriched and reduced combinations in the Myo group compared with NC. Myo, pediatric myocarditis; NC, normal control; *p < 0.05, **p < 0.01, ***p < 0.001.

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  Figure 3. Characteristics of CDR3 length and composition in TCR β CDR3 repertoires. (A) Distribution of CDR3 lengths in the Myo and NC groups; (B) Proportion of CDR3 longer than the mean length (14.8 amino acids); (C) Nucleotide insertion and deletion events at V3’D, V3’I, J5’D, and J5’I sites; (D) Heatmap of amino acid usage frequencies in CDR3 regions. V3’D and J5’D represent deletions at the 3’end of the V gene and 5’end of the J gene, respectively; V3’I and J5’I represent insertions at the same positions. Myo, pediatric myocarditis; NC, normal control. *p < 0.05, ***p < 0.001.

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  Figure 4. Clonotype sharing across individuals in Myo and NC groups. (A) Clonotype overlap matrix among individuals within each group; (B) Jaccard index analysis of shared clonotype frequencies between the Myo and NC groups; (C) Venn diagram showing the number of common and unique CDR3 sequences across groups. Myo, pediatric myocarditis; NC, normal control. Asterisks indicate statistical significance.

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  Figure 5. Annotation of shared clonotypes in the Myo group. (A) McPAS-TCR annotation of clonotypes shared by ≥11 Myo samples but absent from NC controls, showing associations with pathogens, autoimmunity, and cancer; (B) Distribution of pathogen-associated clonotypes from (A), highlighting Mycobacterium tuberculosis, influenza virus, cytomegalovirus, and Epstein–Barr virus; (C) VDJdb annotation revealing associations with multiple viral pathogens, including cytomegalovirus, EBV, SARS-CoV-2, yellow fever virus, hepatitis C virus, HIV-1, and dengue virus; (D) Top 17 high-frequency clonotypes extracted as candidate myocarditis-associated TCR signatures. Myo, pediatric myocarditis; NC, normal control.