Novel Therapeutic Approach Targeting CXCR3 to Treat Immunotherapy Myocarditis

We used a genetic mouse model of PD1 deletion (MRL/Pdcd1−/−) along with a novel drug-treated ICI myocarditis mouse model to recapitulate the disease phenotype. We performed single-cell RNA-sequencing, single-cell T-cell receptor sequencing, and cellular indexing of transcriptomes and epitopes on immune cells isolated from MRL and MRL/Pdcd1−/− mice at serial time points. We assessed the impact of macrophage deletion in MRL/Pdcd1−/− mice, then inhibited CXCR3 (C-X-C motif chemokine receptor 3) in ICI-treated mice to assess the therapeutic effect on myocarditis phenotype. Furthermore, we delineated the functional and mechanistic effects of CXCR3 blockade on T-cell and macrophage interactions. We then correlated the results in human single-cell multiomics data from blood and heart biopsy data from patients with ICI myocarditis.

Single-cell multiomics demonstrated expansion of CXCL (C-X-C motif chemokine ligand) 9/10+CCR2+ macrophages and CXCR3hi (C-X-C motif chemokine receptor 3 high-expressing) CD8+ (cluster of differentiation) effector T lymphocytes in the hearts of MRL/Pdcd1−/− mice correlating with onset of myocarditis development. Both depletion of CXCL9/10+CCR2+ (C-C motif chemokine receptor) macrophages and CXCR3 blockade, respectively, led to decreased CXCR3hi CD8+ T-cell infiltration into the heart and significantly improved survival. Transwell migration assays demonstrated that the selective blockade of CXCR3 and its ligand, CXCL10, reduced CXCR3+CD8+ T-cell migration toward macrophages, implicating this interaction in T-cell cardiotropism toward cardiac macrophages. Furthermore, cardiomyocyte apoptosis was induced by CXCR3hi CD8+ T cells. Cardiac biopsies from patients with confirmed ICI myocarditis demonstrated infiltrating CXCR3+ T cells and CXCL9+/CXCL10+ macrophages. Both mouse cardiac immune cells and patient peripheral blood immune cells revealed expanded TCR s (T-cell receptors) correlating with CXCR3hi CD8+ T cells in ICI myocarditis samples.

 

 

https://www.ahajournals.org/doi/full/10.1161/CIRCRESAHA.124.325652