Targeted C3G delivery by engineered milk exosomes for effective therapy in microplastics-induced colitis

Microplastic polystyrene (PS) ingestion through the food chain induces chronic colitis, with no effective intervention strategy, posing a public health concern globally. Cyanidin-3-O-glucoside (C3G), an anthocyanin abundant in red bayberry, can alleviate colitis while has limited therapeutic efficacy due to its low colonic bioavailability after oral administration. Targeted delivery strategies may enhance colonic C3G concentration and improve its therapeutic efficacy. Exosomes are engineerable nanoparticles with excellent biocompatibility and unique biological activities. In this study, the mucosal addressin cell adhesion molecule 1 (MAdCAM-1, F6) antibody, which specifically binds to colonic inflammatory MAdCAM-1 marker, was conjugated to the raw milk derived-exosome surface to form C3G@Exo-F6, aiming to enhance colonic C3G targeting. In vitro, C3G@Exo-F6 exhibited significantly enhanced stability in simulated digests and was more efficiently taken up by colon cells. In a PS-induced in vivo chronic colitis mice model, C3G@Exo-F6 demonstrated superior efficiency compared to C3G only by inhibiting inflammatory responses, restoring gut barriers integrity and modulating the gut microbiota. Mechanically, 16S rRNA sequencing and untargeted metabolomics demonstrated that C3G@Exo-F6 significantly increased the Lactobacillus abundance and subsequently upregulated the metabolic L-Proline level. Molecular docking identified that L-Proline binds effectively to nuclear receptor subfamily 1 group D member 1 (NR1D1) protein, inhibiting the expression of inflammatory TLR-4/COX-2 pathway. Additionally, Exo-F6 carries exhibited similar therapeutic effects, indicating that exosomes derived from raw milk possess collaborative anti-inflammatory activities. Collectively, these findings emphasize the potential of C3G@Exo-F6 for targeted treatment of chronic colitis, providing a food-derived therapeutic approach for microplastics-induced colonic inflammation.