Transfer of bone marrow niche-residential regulatory T cells ameliorates experimental colitis.

BACKGROUND

Adoptive transfer of regulatory T cells (Tregs) has been proposed as a next-generation treatment approach for the treatment of various inflammatory or autoimmune disorders(Amini et al., 2022; Bluestone et al., 2023, 2015; Dall'Era et al., 2019; Chandran et al., 2017; Laukova and Glatman Zaretsky, 2023; Voskens et al., 2023; Canavan et al., 2016, inclusive of inflammatory bowel diseases (IBD). Identification of the appropriate Treg populations as donor sources for effective cell therapy is of great importance. We have recently identified specialized Tregs that localize within the hematopoietic stem cell (HSC) microenvironments(Fujisaki et al., 2011; Hirata et al., 2018, 2019, 2015; Kakiuchi et al., 2021a, 2021b; Furuhashi et al., 2025 of bone marrow (BM), termed HSC niches. These BM niche Tregs exhibit robust anti-inflammatory and pro-regenerative effects and render HSCs immune privileged. The transfer of BM niche Tregs exhibits high therapeutic effects against BM transplantation and injury(Hirata et al., 2018; Kakiuchi et al., 2021b. Yet, the treatment effects of transferred BM niche Tregs in non-BM disease settings remain unknown.

OBJECTIVES

We investigated the therapeutic effects of transfer of BM niche Tregs for IBD using mouse models of experimental colitis. To identify the key effector molecule of niche Tregs, we further examined the roles of cell-surface ectoenzyme CD39 expressed at high levels by BM niche Tregs.

STUDY DESIGN

Mouse colitis was induced by administering dextran sulfate sodium salt. Subsequently, the mice received intravenous injections of BM niche Tregs, BM non-niche Tregs, lymph node Tregs, or vehicle alone. We compared these treatment effects on clinical scores, histopathological features and profiles of immune cells. We also tested how targeted deletion of CD39 in the adoptively transferred Tregs impacted experimental outcomes.

RESULTS

The transfer of as few as 1.5 × 10 BM niche Tregs per mouse ameliorated clinical and histopathological features of the mouse colitis far better than the transfer of other Tregs. The transfer of BM niche Tregs inhibited the generation of Th17 cells and promoted the regeneration and recovery of the colon tissue. Targeted deletion of CD39 in Tregs abrogated therapeutic effects of transferred BM niche Tregs.

CONCLUSION

We show robust therapeutic effects of the transfer of BM niche Tregs in the experimental model of colitis. Donor niche Tregs mediate anti-inflammatory and pro-regenerative effects via Treg CD39. Our work suggests the transfer of BM niche Tregs is a promising approach to treat colitic disorders and boost tissue regeneration.