Single-cell landscapes defines peripheral immune heterogeneity of cardiac allograft rejection subtypes
Z Zou, S Zheng, S LiuAbstract
Background
Cardiac allograft rejection (CAR) is a major impediment to long-term allograft survival, comprising antibody-mediated rejection (AMR) and acute cellular rejection (ACR). The distinct peripheral immune mechanisms driving these rejection types remain uncharacterized at single-cell resolution.
Methods
We performed single-cell RNA sequencing of the peripheral blood mononuclear cells from 3 groups of heart transplant recipients, including 3 patients with AMR, 3 patients with ACR, and 3 non-rejection control subjects. Bioinformatics was used to identify the cellular populations, describe the cell functions, and depict cellular developmental trajectories and interactions. Differences among the 2 types of CAR at the cellular level were summarized. Pathological staining and enzyme-linked immunosorbent assay were performed to validate the key findings.
Results
Four cell types were identified among 47,303 cells from patients with heart transplantation. Myeloid cells were the largest population, followed by the NK cells, T lymphocytes, and B lymphocytes. The 2 types of CAR had distinct cellular compositions. The integrative analysis of our single-cell RNA sequencing and multiplex immunohistochemical revealed key cellular subpopulations involved in the pathogenesis of patients with CAR. AMR featured cytotoxic CD8⁺ T cells and CXCL10⁺ macrophages, while ACR was characterized by CD66b⁺ neutrophils exhibiting neutrophil extracellular traps formation and immunosuppression. The intercellular communication analysis revealed that macrophages and neutrophils were at the center of the communication network, MIF (macrophage migration inhibitory factor) and RESISTIN (resistin) were their pivotal pathways, respectively.
Conclusion
The cellular landscape differed among the 2 types of CAR, which might explain their differences in pathological immune microenvironment, and offer novel mechanistic insights and potential therapeutic targets for rejection subtypes.Overview of the immune landscapesFor image description, please refer to the figure legend and surrounding text.Flowchart of the studyFor image description, please refer to the figure legend and surrounding text.