Integrated analysis of single-cell data on role of NKG7high CD8+ Teff cells in driving immune-related adverse events.

e24114 Background: Immune-related adverse events (irAEs) frequently occur during immunotherapy and can impact various organ systems, which dampen the clinical outcomes of immune checkpoint inhibitors (ICIs). However, the precise immune hallmarks associated with irAEs remain further explored. Methods: We collected public (Bukhari et al., Zhu et al., Su et al., and Ma et al.) and our own scRNA-seq data across patients with different irAE types or without irAEs. By comparing T cell compositions between irAE and no-irAE patients, the subcluster correlated with the occurrence of irAE was identified. Subsequently, the integrated analyses were performed to explore its mechanisms in driving irAEs in both peripheral blood and local tissues. Results: Compared to no-irAE patients, a subcluster of effector T (T eff ) cells was observed to increase notably in the peripheral blood of irAE patients during immunotherapy. This specific subcluster, named "NKG7 high CD8 + T eff cells," was characterized by the significant expression of effector genes such as GZMH, CCL5, and especially NKG7. In contrast to other CD8 + T cells, the NKG7 high CD8 + T eff cells exhibited stronger cytotoxicity functions, increased exosome secretion, and enhanced MIF-CD74 interaction with monocytes, which suggests the mechanistic link between its increased infiltration and the development of irAEs. Further investigation showed these characteristics were more remarkable in NKG7 high CD8 + T eff from irAE patients than no-irAE patients. Subsequently, the increase of NKG7high CD8+ Teff during immunotherapy was validated in our own scRNA from immune thyroiditis patients, which was not observed in no-irAE patients. Across various irAE types, NKG7 high CD8 + T eff subsets, along with their NKG7 expression, demonstrated heightened infiltration and expression in immune-related arthritis and myocarditis samples. After investigating the role of NKG7 high CD8 + T eff in peripheral blood, we focused on its distribution and roles in local irAE tissue. NKG7 high CD8 + T eff cells accumulated in immune-related thyroiditis tissues, and recruited macrophages through the IFNG and CSF1 signaling pathways, thereby inducing an immune overreaction. Meanwhile, in immune-related myocarditis mice heart tissues, NKG7 high CD8 + T eff cells could interact with macrophages via the SPP1 signaling pathway and cause endothelial cell damage through the FASL-FAS pathway. Conclusions: This comprehensive study revealed the intricate mechanisms of NKG7 high CD8 + T eff in inducing irAEs, providing valuable insights into their roles and potential implications in irAE treatment.