Abstract
BACKGROUND: Liver transplantation is the only effective way for end-stage liver disease. Rejection remains the leading cause of graft failure. The dynamic changes of intrahepatic immune cells involved in rejection are not completely understood. METHODS: We integrated single-cell RNA sequencing and spatial transcriptomics (ST) to analyze graft tissues from multiple stages of human liver transplantation. ST enabled high-resolution mapping of immune cell states and spatial distribution within liver grafts. RESULTS: We identified several transplantation-associated T cell (taT) subsets, including CD4(+) effector-like T cells (Teff_like), CD8(+) precursor exhausted T cells (Tpex), and CD8(+) transitional effector-like T cells (tTeff_like). The CD4(+) Teff_like subset highly expressed chemokines such as CCL3. The CD8(+) tTeff_like subset represented an intermediate state transitioning from the CD8(+) Tpex subset toward terminal exhaustion and was enriched in the immune activity pathway. Monocyte_PPARG, enriched in the rejection group, may be recruited by CD4(+) Teff_like via the MIF-(CD74+CD44) pathway and subsequently promote CD8(+) Tpex to tTeff_like differentiation through the ICAM1-LFA1 pathway. ST suggested that these immune subsets dominated the rejecting liver grafts. CONCLUSION: These findings highlight the potential roles and spatial distribution of taT subsets in rejecting liver grafts, providing insights into local immune regulation and the development of targeted therapeutic strategies.