Engineered extracellular vesicles reprogram T cells by targeting PD-1 and PHB1 signaling in inflammatory bowel disease.

Current therapies for inflammatory bowel disease (IBD) often fail to achieve complete remission and are associated with systemic toxicity owing to their broad immunosuppressive effects. To overcome these limitations, we developed a bioengineered extracellular vesicle (EV) platform that modulates key immune signaling pathways to efficiently restore the T-cell balance in inflamed intestinal tissues. EVs derived from Wharton's jelly mesenchymal stem cells were engineered to display PD-L1 on their surface and encapsulate miR-27a-3p. Surface PD-L1 engages the PD-1 checkpoint in activated T cells, attenuating T-cell receptor signaling via SHP2-mediated dephosphorylation of ZAP70 and AKT. In parallel, miR-27a-3p suppresses prohibitin 1 (PHB1), a mitochondrial regulator of Th17 cell bioenergetics and inflammatory function, thereby reducing Th17 polarization and increasing the number of FOXP3⁺ regulatory T cells. These dual-targeting EVs preferentially localized to inflamed intestinal tissues via chemokine (CCR2/CXCR4) and PD-1-dependent mechanisms. In humanized mouse models of colitis, these EVs attenuated mucosal inflammation, suppressed effector T-cell responses, and preserved epithelial integrity. In IBD patient-derived colonoid cultures, PD-L1/miR-27a-3p EVs maintained epithelial viability and barrier integrity without inducing cytotoxicity or structural disruption. Transcriptomic and single-cell analyses revealed the downregulation of inflammatory and exhaustion signatures, along with the enrichment of regulatory subsets. Collectively, this study presents a cell-free immunotherapeutic approach that reprograms T cells in inflamed tissues through the PD-1 and mitochondrial signaling pathways while maintaining intestinal epithelial integrity, offering a promising therapeutic strategy for IBD and other T cell-driven inflammatory disorders.