Single-cell transcriptomics reveals the interaction between fibroblasts and activated immune cells

Background: Slow transit constipation (STC) is an intestinal disease characterized by colonic dyskinesia which involves multiple factors such as neuroendocrine, substance metabolism, gut microbiota, ion channels, and aquaporin. Increasing evidence indicates that modulation of immune signaling, activation of immune cells, and secretion of cytokines impact oxidative stress, disruption of the intestinal mucosal barrier and the subsequent intestinal dysfunction in STC. However, the landscape of the immune microenvironment (IME) and the disease-specific cell type in STC patients is unclear, and the detailed mechanism of how immune cells affect stromal cells during chronic inflammation is still lacking. Materials and methods: We performed single-cell RNA sequencing (scRNA-seq) on 6 STC cases and 6 control cases to elucidate the IME in STC patients. By identifying differentially expressed genes and pathways between groups, tracking cell differentiation trajectories, and constructing an integrated analysis of intercellular communication, we aimed to elucidate the potential mechanisms of specific immune cell types. Results: We identified STC-specific XCL2 + CD8 + T cells, which exhibit extensive intercellular communication with other immune cells and intestinal stromal cells. B cells and myeloid cells could promote the immune function of XCL2 + CD8 + T cells by CD137 co-stimulatory molecules. Afterwards, the activated XCL2 + CD8 + T cells enhanced the secretion of pro-inflammatory cytokines of fibroblasts through IFNG and TNFSF14 signaling pathways. Additionally, fibroblasts exert immune regulation on XCL2 + CD8 + T cells through the NECTIN signaling pathway. Conclusion: These results suggested that STC-specific XCL2 + CD8 + T cells might influence the homeostasis of the IME and further disrupt intestinal function.