Oral delivery of anti-mCD80 nanobody-engineered probiotic bacterial nanovesicles for macrophage-targeted Il17ra silencing in colitis.

Inflammatory bowel disease remains challenging to treat because effective intervention requires localized suppression of mucosal inflammation together with restoration of tissue homeostasis. Here, a hierarchically engineered oral nanotherapeutic is developed based on Lactobacillus rhamnosus GG-derived bacterial nanovesicles (BNVs) for inflammatory macrophage-targeted gene silencing in colitis. The vesicles are genetically engineered to display an anti-mCD80 nanobody, loaded with siIl17ra, and further encapsulated within calcium alginate microcapsules to improve gastrointestinal protection and enable gastrointestinal protection and intestinal-fluid-associated release in the lower gut. The resulting system preserves nanoscale vesicular morphology, exhibits favorable cytocompatibility, and shows enhanced uptake by inflammatory macrophages after nanobody decoration. Following internalization, siIl17ra/CD80-BNVs effectively suppress Il17ra expression and reprogram macrophages toward a pro-repair phenotype. Microcapsule incorporation further improves siRNA retention, restrains premature release under acidic conditions, and promotes sustained release under intestinally relevant pH conditions. After oral administration, MC-siIl17ra/CD80-BNVs display enhanced colorectal retention and markedly alleviate dextran sulfate sodium-induced colitis, as evidenced by reduced disease activity, attenuated histopathological injury, enhanced epithelial regeneration, decreased inflammatory mediator expression, and reduced NF-κB/caspase-associated marker changes. This work establishes a microbiota-inspired oral nanomedicine platform for localized immunomodulation and mucosal repair in colitis.