Single-cell RNA sequencing atlas of intestinal injury induced by different clinical treatments in colorectal cancer patients.

Abstract

12039 Background: Colorectal cancer (CRC) patients often experience intestinal injury due to various treatment regimens, including chemotherapy (CT), chemoradiotherapy (CRT), and chemoradioimmunotherapy (ICRT). Despite advances in treatment, the underlying mechanisms of treatment-induced intestinal injury remain poorly understood. Methods: We performed single-cell RNA sequencing and histological staining on intestinal samples obtained from 18 colorectal cancer patients undergoing different treatment regimens, including untreated (CTRL), CT, CRT, and ICRT groups. We also employed bulk RNA sequencing to compare paired cancer and normal tissues from ICRT patients, identifying similarities and differences in gene expression patterns between the cancer and normal tissues. Results: Histological staining showed that there were no morphological changes in CT, while the damage in CRT was obvious, and the damage in ICRT was even more severe. Intestinal epithelial cells exhibit distinct differentiation trajectories into secretory and absorptive lineages. CRT-induced damage triggers reverse differentiation via revival stem cells (revSCs), driven by fetal-like genes like CLU, while ICRT disrupts this process. In CD8+T cells, effector T cells (TEFF) increase significantly in the ICRT group and differentially expressed genes (DEG) revealed unique patterns across different treatments, including upregulation of senescence-related genes in CRT and interferon- and TNF-related genes in ICRT, highlighting potential therapeutic targets for treatment-induced intestinal injury. In B cells, distinct differentiation pathways were observed, with CRT increasing atypical memory (Atm) B and ICRT promoting germinal center (GC) B, the latter correlating with follicular helper T (TFH) cells and potentially indicating tertiary lymphoid structure (TLS) formation, similar to the patterns of tumor response after ICRT. So we conducted bulk RNA sequencing analysis between paired tumor and normal tissues, which revealed a correlated expression of effector markers, suggesting a shared biological pattern between tissue damage and tumor killing. Also, patients in the ICRT group showed a significant correlation between clinical intestinal injury scores (LARS) and tumor regression grade (TRG), which means we can predict the treatment efficacy of ICRT by a more direct and convenient way. We also performed metabolism analysis and found tryptophan metabolism was significantly altered following CRT and ICRT treatments, closely linked to epithelial repair and inflammation, highlighting tryptophan metabolism can be used as treatment of intestinal injury. Conclusions: Our study presents a comprehensive single-cell atlas of treatment-induced intestinal injury in CRC patients, offering insights for future strategies to reduce treatment-related intestinal damage.