Biology subjects

Amrute, J.

Publications and source records attributed to Amrute, J..

3 recordsLinked to original sources

bioRxiv2023

Expansion of Disease Specific Cardiac Macrophages in Immune Checkpoint Inhibitor Myocarditis

BackgroundImmune 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 pathologically 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. MethodsWe employed an established murine ICI myocarditis model (Ctla4+/-Pdcd1-/- mice) to explore the cardiac immune landscape using single-cell RNA-sequencing, immunostaining, flow cytometry, in situ RNA hybridization and molecular imaging and antibody neutralization studies. ResultsWe 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 highly expressing Cxcl9, Cxcl10, Gbp2b, and Fcgr4 that originated from CCR2+ monocytes. Importantly, a similar macrophage population expressing CXCL9, CXCL10, and CD16 (human homologue of mouse FcgR4) was found selectively expanded 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-{gamma} and CXCR3 signaling pathways. Depleting CD8+T-cells, macrophages, and blockade of IFN-{gamma} signaling blunted the expansion of Cxcl9+Cxcl10+macrophages in the heart and attenuated myocarditis suggesting that this interaction was necessary for disease pathogenesis. ConclusionThese data demonstrate that ICI-myocarditis is associated with the expansion of a specific population of IFN-{gamma} induced inflammatory macrophages and suggest the possibility that IFN-{gamma} blockade may be considered as a treatment option for this devastating condition.

immunology↗

bioRxiv2021

Donor Macrophages Modulate Rejection after Heart Transplantation

BackgroundCellular rejection after heart transplantation imparts significant morbidity and mortality. Current immunosuppressive strategies are imperfect, target recipient T-cells, and have a multitude of adverse effects. The innate immune response plays an essential role in the recruitment and activation of T-cells. Targeting the donor innate immune response would represent the earliest interventional opportunity within the immune response cascade. There is limited knowledge regarding donor immune cell types and functions in the setting of cardiac transplantation and no current therapeutics exist for targeting these cell populations. MethodsUsing genetic lineage tracing, cell ablation, and conditional gene deletion, we examined donor mononuclear phagocyte diversity and function during acute cellular rejection of transplanted hearts in mice. We performed single cell RNA sequencing on donor and recipient macrophages, dendritic cells, and monocytes at multiple timepoints after transplantation. Based on our single cell RNA sequencing data, we evaluated the functional relevance of donor CCR2+ and CCR2- macrophages using selective cell ablation strategies in donor grafts prior to transplant. Finally, we perform functional validation of our single cell-derived hypothesis that donor macrophages signal through MYD88 to facilitate cellular rejection. ResultsDonor macrophages persisted in the transplanted heart and co-existed with recipient monocyte-derived macrophages. Single-cell RNA sequencing identified donor CCR2+ and CCR2- macrophage populations and revealed remarkable diversity amongst recipient monocytes, macrophages, and dendritic cells. Temporal analysis demonstrated that donor CCR2+ and CCR2- macrophages were transcriptionally distinct, underwent significant morphologic changes, and displayed unique activation signatures after transplantation. While selective depletion of donor CCR2- macrophages reduced allograft survival, depletion of donor CCR2+ macrophages prolonged allograft survival. Pathway analysis revealed that donor CCR2+ macrophages were being activated through MYD88/NF-{beta} signaling. Deletion of MYD88 in donor macrophages resulted in reduced antigen presenting cell recruitment, decreased emergence of allograft reactive T-cells, and extended allograft survival. ConclusionsDistinct populations of donor and recipient macrophages co-exist within the transplanted heart. Donor CCR2+ macrophages are key mediators of allograft rejection and inhibition of MYD88 signaling in donor macrophages is sufficient to suppress rejection and extend allograft survival. This highlights the therapeutic potential of donor heart-based interventions.

immunology↗

bioRxiv2021

Single Cell Transcriptomics Reveals Cell Type Specific Diversification in Human Heart Failure

Heart failure represents a major cause of morbidity and mortality worldwide. Single cell transcriptomics have revolutionized our understanding of cell composition and associated gene expression across human tissues. Through integrated analysis of single cell and single nucleus RNA sequencing data generated from 45 individuals, we define the cell composition of the healthy and failing human heart. We identify cell specific transcriptional signatures of heart failure and reveal the emergence of disease associated cell states. Intriguingly, cardiomyocytes converge towards a common disease associated cell state, while fibroblasts and myeloid cells undergo dramatic diversification. Endothelial cells and pericytes display global transcriptional shifts without changes in cell complexity. Collectively, our findings provide a comprehensive analysis of the cellular and transcriptomic landscape of human heart failure, identify cell type specific transcriptional programs and states associated with disease, and establish a valuable resource for the investigation of human heart failure.

genomics↗