IgG N-glycosylation as a novel biomarker for immune checkpoint inhibitor-associated myocarditis: a comparative glycomic study

Background Immune checkpoint inhibitor-associated myocarditis (irAE-MC) is a rare but potentially fatal complication with limited diagnostic specificity using conventional biomarkers. Glycosylation is a crucial post-translational modification that modulates IgG effector functions and reflects systemic inflammatory status. However, whether specific IgG N-glycosylation patterns can serve as biomarkers to distinguish irAE-MC from patients receiving immune checkpoint inhibitor (ICI) treatment remains unexplored. Purpose To investigate the association between specific IgG N-glycosylation patterns and the development of irAE-MC, and to evaluate the diagnostic potential of these glycan signatures in distinguishing irAE-MC from patients prior to ICI (Pre-ICI) and ICI-treated patients without irAEs (Non-irAE) patient group. Methods We analyzed IgG N-glycosylation in three age- and sex-matched cohorts: patients with irAE-MC (n=38), Pre-ICI (n=46) and Non-irAE (n=44). Profiling was conducted using high-resolution mass spectrometry. Group differences between cohorts were assessed in R Studio using one-way analysis of variance (ANOVA) followed by Tukey’s post-hoc test for normally distributed variables, and the Mann–Whitney U test for non-normally distributed variables. Results The three cohorts were comparable in age and sex [median 65.5–68.5 years; 63.1%–71.7% male; all P > 0.05]. Heatmap and profiling analyses revealed that IgG N-glycosylation patterns in irAE-MC were distinct from those in pre-ICI and non-irAE groups. Specifically, H3N4F1was significantly decreased, while H5N4F1 and H5N4F1E1 were significantly elevated in irAE-MC compared with both pre-ICI and non-irAE groups (all P < 0.05). Among derived glycan traits, galactosylation-related features, including CG, A2FG, and A2S0G, were significantly elevated in the irAE-MC group compared with pre-ICI and non-irAE group (all P < 0.05). In contrast, the bisecting N-acetylglucosamine (GlcNAc)-related trait A2FSB was significantly reduced in irAE-MC compared with both pre-ICI and non-irAE groups (all P < 0.05). No significant differences were observed between the pre-ICI and non-irAE groups for these traits (Figure 2). Conclusion These distinct IgG N-glycosylation patterns reflect the unique systemic inflammatory milieu of ICI induced myocardial injury. Our findings suggest that specific glycan signatures serve as novel non-invasive biomarkers for the early diagnosis of irAE-MC in patients receiving ICI therapy.