Donkey Milk Exosomes Protect Against Dextran Sulfate Sodium-Induced Colitis by Delivering Anti-Inflammatory miRNAs and Reshaping Gut Microbiota.

Ulcerative colitis treatment is hindered by side effects, relapse, individual variability, and poor intestinal barrier repair. Milk‑derived exosomes (exo) are safe; carry anti‑inflammatory miRNAs/proteins; and regulate immunity, epithelial repair, and gut microbiota. Here, we isolated donkey milk exo and characterized them. Exo showed typical features (TSG101, CD63, CD9) and contained 1212 miRNAs, with eca‑let‑7 g and eca‑miR‑148a being most abundant. Oral exo administration in DSS‑induced colitis mice significantly reduced body weight loss, colon shortening, and disease activity index. Exo enhanced intestinal barrier by upregulating Occludin, Claudin‑1, and ZO‑1; lowered pro‑inflammatory cytokines (IL‑1β, IL‑6, TNF‑α); increased anti‑inflammatory IL‑10; and attenuated oxidative stress and neutrophil infiltration. Mechanistically, eca‑let‑7 g directly targeted TLR4 3'UTR to inhibit NF‑κB, while eca‑miR‑148a targeted NLRP3 3'UTR to suppress the NLRP3‑Caspase‑1‑IL‑18 axis. Moreover, exo reshaped gut microbiota by reducing pathogenic Bacteroides and Desulfovibrio and enriching beneficial Akkermansia muciniphila and Turicibacter. Collectively, donkey milk exo alleviate DSS‑evoked colitis through two distinct mechanisms: miRNA‑mediated suppression of inflammatory pathways and gut microbiota modulation. These findings support donkey milk exo as a natural, orally deliverable therapeutic option for inflammatory bowel disease.