Bletilla striata-derived extracellular vesicles armed probiotic by supramolecular assembly ameliorates colitis via macrophage modulation and microbiota restoration

Background Inflammatory bowel disease (IBD) represents major global health challenges, but current treatments often are limited by efficacy loss, infection risks, and disruption of gut homeostasis. Novel therapies are needed to actively promote mucosal repair and restore immune balance. Results This study develops a nano-biotherapeutic by conjugating extracellular vesicles derived from Bletilla striata (BEVs) with the probiotic Escherichia coli Nissle 1917 (EcN) via supramolecular assembly. BEVs contained protocatechualdehyde as a key bioactive metabolite to suppress M1 macrophage polarization and ROS production. EcN@BEVs treatment significantly restored epithelial barrier integrity with the upregulated expression of ZO-1 and Occludin, and reversed microbiota dysbiosis by increasing the Bacillota/Bacteroidota ratio. scRNA-seq and INVADE-seq analyses confirmed that EcN@BEVs promoted a shift from pro-inflammatory to anti-inflammatory macrophage phenotypes and reduced intracellular bacterial invasion. Conclusions The EcN@BEVs complex demonstrates significant therapeutic potential for colitis through a multi-faceted mechanism involving enhanced probiotic delivery, direct anti-inflammatory action, gut microbiota restoration, and mucosal immunity reprogramming. This study presents a promising integrated nanotherapeutic strategy for IBD treatment under cross-species collaboration.