Exosomes derived from cancer cells relieve inflammatory bowel disease in mice.

Exosome therapy has garnered significant attention due to its natural delivery capabilities, low toxicity, high biocompatibility, and potential for personalised treatment through engineering modifications. Recent studies have highlighted the ability of tumour cell-derived exosomes (TDEs) to interact with immune cells or modify the immune microenvironment to suppress host immune responses, as well as their unique homing ability to parental cells. The core question of this study is whether this immunomodulatory property of TDEs can be utilised for the immunotherapy of inflammatory diseases. In our experiments, we prepared exosomes derived from murine colon cancer cells CT26 (CT26 exo) using ultracentrifugation, characterised them, and conducted proteomic analysis. The therapeutic potential of CT26 exo was evaluated in our dextran sulphate sodium salt (DSS)-induced inflammatory bowel disease (IBD) mouse model. Compared to the control and 293 T exo treatment groups, mice treated with CT26 exo showed a reduction in the disease activity index (DAI) and colon shortening rate, with no noticeable weight loss. Haematoxylin and eosin (H&E) staining of colon paraffin sections revealed reduced inflammatory infiltration and increased epithelial goblet cells in the colons of CT26 exo-treated group. Furthermore, we conducted preliminary mechanistic explorations by examining the phenotyping and function of CD4+ T cells and dendritic cells (DCs) in the colonic lamina propria of mice. The results indicated that the ameliorative effect of CT26 exosomes might be due to their inhibition of pro-inflammatory cytokine secretion by colonic DCs and selective suppression of Th17 cell differentiation in the colon. Additionally, CT26 exo exhibited good biosafety. Our findings propose a novel exosome-based therapeutic approach for IBD and suggest the potential application of TDEs in the treatment of inflammatory diseases.