Modulation of Inflammation and Gut Microbiota by a Bifidobacterium longum Extracellular Vesicle-Based Drug Delivery System for Alleviating Inflammatory Bowel Disease

Purpose: Inflammatory bowel disease (IBD) is a chronic inflammatory disorder strongly associated with intestinal microbial dysregulation. Although 5-aminosalicylic acid (5-ASA) is widely used in the clinical management of IBD, its therapeutic efficacy is often limited. To address this, the present study aimed to develop a bifidobacterium-derived extracellular vesicle-based drug delivery system (B-MVs@5-ASA) to enhance the therapeutic outcomes of IBD. Methods: B-MVs were isolated by PEG precipitation and loaded with 5-ASA via sonication to obtain B-MVs@5-ASA. Their morphology, particle size, zeta potential, and encapsulation efficiency were analyzed using TEM, DLS, and UV spectrophotometry. Cellular uptake, cytotoxicity (LDH and NO assays), and anti-inflammatory effects were assessed in RAW 264.7 and Caco-2 cells. A DSS-induced colitis mouse model was established to evaluate therapeutic efficacy. Cytokines (ELISA), colon histopathology (H&E), tight-junction proteins (IF), and gut microbiota composition (16S rRNA sequencing) were systematically analyzed. Results: B-MVs@5-ASA exhibited a particle size of 104.3 ± 2.81 nm and an encapsulation efficiency of 11.14% ± 3.63%. B-MVs@5-ASA exhibited the strongest anti-inflammatory effect in vitro and most effectively alleviated DSS-induced colitis in vivo, outperforming monotherapies in reducing inflammation, tissue damage, and enhancing barrier integrity. B-MVs@5-ASA further promoted goblet cell regeneration and beneficially modulated the gut microbiota by enriching Akkermansia and suppressing Escherichia, thereby restoring microbial homeostasis. Conclusions: B-MVs@5-ASA provides potent anti-inflammatory and mucosal-protective effects by modulating cytokine balance, enhancing epithelial barrier function, and reshaping gut microbiota. These findings highlight probiotic vesicle-based nanoplatforms as a safe and promising strategy for targeted IBD therapy.