Understanding the immune mechanisms associated with liver transplantation (LT), particularly the involvement of tissue-resident memory T cells (TRMs), represents a significant challenge.
This study employs a multi-omics approach to analyse liver transplant samples from both human (n=17) and mouse (n=16), utilizing single-cell RNA sequencing, bulk RNA sequencing, and immunological techniques. Our findings reveal a comprehensive T cell-centric landscape in LT across human and mouse species, involving 235,116 cells. Notably, we found a substantial increase in CD8+ TRMs within rejected grafts compared to stable ones. The elevated presence of CD8+ TRMs is characterised by a distinct expression profile, featuring upregulation of tissue-residency markers (CD69, CXCR6, CD49A and CD103+/-,), immune checkpoints (PD1, CTLA4, and TIGIT), cytotoxic markers (GZMB and IFNG) and proliferative markers (PCNA and TOP2A) during rejection. Furthermore, there is a high expression of transcription factors such as EOMES and RUNX3. Functional assays and analyses of cellular communication underscore the active role of CD8+ TRMs in interacting with other tissue-resident cells, particularly Kupffer cells, especially during rejection episodes.
These insights into the distinctive activation and interaction patterns of CD8+ TRMs suggest their potential utility as biomarkers for graft rejection, paving the way for novel therapeutic strategies aimed at enhancing graft tolerance and improving overall transplant outcomes.