Abstract 4366283: Increased Immune Cell-Cell Communication and Pro-Inflammatory Signaling in Clonal Hematopoiesis of Indeterminate Potential (CHIP)-Positive Peripheral Blood in Immune Checkpoint Inhibitor Myocarditis

Introduction: Clonal hematopoiesis of indeterminate potential (CHIP) was recently shown to be an independent risk factor for immune checkpoint inhibitor (ICI)-associated myocarditis. However, the mechanisms by which CHIP may contribute to immune dysregulation in this context remain poorly understood. Research Questions: How does CHIP contribute to immune dysregulation in cancer patients receiving ICIs, and what cytokine-producing cell types and pathways drive CHIP-associated inflammation? Methods: To investigate this, we implemented the CellChat framework to single-cell RNA sequencing (scRNA-seq) data in order to infer and compare cell-cell communication networks. We analyzed scRNA-seq data from six post-ICI myocarditis patients, three of whom were CHIP-positive and three CHIP-negative from Yale. Using CellChat, we constructed condition-specific intercellular signaling networks and compared overall signaling activity, communication strength, and pathway usage across groups. We further validated the findings with two other cell-cell interaction analysis tools, DominoSignal and CellPhoneDB. Results: CHIP-positive samples exhibited a higher number (3440 vs 2466 CHIP vs no CHIP) and strength of ligand-receptor interactions compared to CHIP-negative samples (110 vs 75, CHIP vs no CHIP), indicating globally elevated intercellular signaling (Figure 1). Network and heatmap visualizations revealed increased cell-cell communication in CHIP positive patients compared to CHIP negative patients particularly among immune cell types, including monocytes, platelets, plasmacytoid dendritic cells, and naive B cells. Directional analysis showed enhanced outgoing signals from naive B cells and increased incoming signals to macrophages and plasmacytoid dendritic cells in CHIP-positive samples. Of note, increased platelet interactions with native CD4 and CD8 T cells were noted. Pathway-level analysis highlighted upregulation of pro-inflammatory and pro-platelet activation signaling, including TNF, CXCL, CD30, and CD40 (Figure 2). Conclusion: These findings suggest that CHIP is associated with a pro-inflammatory signaling environment that contributes to ICI myocarditis. These findings support its potential as a biomarker for risk stratification and as a target for pathway-specific anti-inflammatory therapies. For future directions, these results will be validated with external ICI myocarditis cohorts.