Single-cell RNA-seq reveals the immune profile changes in patients with diarrhoeal-irritable bowel syndrome.

Diarrhea-predominant irritable bowel syndrome (IBS-D) is characterized by recurrent abdominal pain and chronic diarrhea. T lymphocytes, which play a crucial role in gut inflammation and immune responses, may significantly contribute to the pathophysiology of IBS-D. However, the exact mechanisms by which T lymphocytes affect IBS-D remain unclear. The precise pathways and interactions involved in IBS-D are still to be determined. We conducted single-cell RNA sequencing on blood samples from 4 IBS-D patients and 4 healthy controls. Following data preprocessing, we conducted subsequence bioinformatics analysis. Additionally, serum and colon tissue samples from IBS-D rat models were analyzed using ELISA and three-parameter fluorescence to further elucidate the T lymphocytes landscape associated with IBS-D. A total of 45,649 cells were classified into four distinct cell types. Among them, T lymphocytes were further subdivided into 20 unique clusters. Novel markers that were highly expressed in T lymphocytes were identified. Dysregulation of HIF-1α pathway, NF-kappa B pathway, and IL-17 signaling pathway, were observed through trajectory analysis. Additionally, single-cell regulatory network inference and clustering analysis revealed the FOS signaling pathway as a potential therapeutic target for IBS-D. Furthermore, we detected abnormally elevated levels of PLK3 and NFKBIZ in the serum and colon tissues of the IBS-D rat model. Our study mapped the communication atlas of T lymphocytes that may influence the pathophysiology of IBS-D. This study uncovers novel molecular features and identifies potential therapeutic targets of T lymphocytes in IBS-D, thereby advancing our understanding of the disease and expanding treatment options.