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T cells and monocyte-derived myeloid cells mediate immunotherapy-related hepatitis in a mouse model

ABSTRACT: Immune checkpoint inhibitors (ICIs) are associated with immune-related adverse events (irAEs) which are more severe when ICIs are used in combination. A mouse model was developed to elucidate the molecular mechanisms of immune-related hepatitis, one of the common irAEs associated with ICIs. Molecular profiling by single cell RNA sequencing was performed on Pdcd1-/- mice treated with anti-CTLA4 and/or the IDO1 inhibitor epacadostat or a 4-1BB agonistic antibody. ICI combination-induced hepatitis and 4-1BB agonist-mediated hepatitis share similar features yet maintain distinct immune signatures. Both were characterized by an expansion of activated T cells. Single-cell transcriptomics revealed that the hepatitis induced by combination ICIs is associated with a robust immune activation signature in all subtypes of T cells and T helper 1 skewing. Expression profiling revealed a central role for IFNγ and liver monocyte-derived macrophages in promoting a pro-inflammatory T-cell response to ICI combination and 4-1BB agonism.

ORGANISM(S): Mus musculus

PROVIDER: GSE217917 | GEO | 2022/11/14

REPOSITORIES: GEO

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Project description:Immune checkpoint inhibitors (ICIs), antibodies targeting PD-1/PD-L1 or CTLA4 have revolutionized cancer management but are associated with devastating immune-related adverse events (irAEs) including myocarditis. The main risk factor for ICI myocarditis is the use of combination PD-1 and CTLA4 inhibition. ICI-myocarditis is often fulminant and is pathophysiologically characterized by myocardial infiltration of T lymphocytes and macrophages. While much has been learned regarding the role of T-cells in ICI-myocarditis, little is understood regarding the identity, transcriptional diversity, and functions of infiltrating macrophages. We employed an established murine ICI myocarditis model (Ctla4+/-Pdcd1-/- mice) to explore the cardiac immune landscape using single-cell RNA-sequencing, immunostaining, and molecular imaging. We observed marked increases in CCR2+ monocyte-derived macrophages and CD8+ T-cells in this model. The macrophage compartment was heterogeneous and displayed marked enrichment in an inflammatory CCR2+ subpopulation expressing Cxcl9, Cxcl10, Gbp2b, and Fcgr4 that originated from CCR2+ monocytes. Importantly, a similar macrophage population expressing CXCL9, CXCL10, and CD16α (human homologue of mouse FcgR4) were found selectively in patients with ICI myocarditis compared to other forms of heart failure and myocarditis. In silico prediction of cell-cell communication suggested interactions between T-cells and Cxcl9+Cxcl10+ macrophages via IFN-γ and CXCR3 signaling pathways. Depleting CD8+T-cells and blockade of IFN-γ signaling blunted the emergence of Cxcl9+Cxcl10+ macrophages in the heart and attenuated myocarditis suggesting that this interaction was necessary for disease pathogenesis. Collectively, these data demonstrate that ICI-myocarditis is associated with the emergence of a specific population of inflammatory macrophages and suggest the possibility that IFN-γ blockade may serve as an effective treatment for this devastating condition.