Bovine colostrum-derived extracellular vesicles modulate gut microbiota and alleviate atopic dermatitis via the gut-skin axis.

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by immune dysregulation and a disrupted gut-skin axis. Emerging evidence suggests that the gut microbiota and their metabolites play a critical role in pathogenesis and potential treatment of AD. However, therapeutic strategies targeting the gut microbiota that aim to alleviate AD remain underexplored. Therefore, this study investigated the potential of bovine colostrum-derived extracellular vesicles (BCEVs) to ameliorate AD symptoms by modulating the gut microbiota and intestinal metabolites. AD was induced in mice using 2,4-dinitrochlorobenzene, followed by the oral administration of BCEVs. Skin lesions were assessed histologically to evaluate disease severity. Allergic and immune responses were measured by analyzing serum immunoglobulin E (IgE) levels and cytokine profiles, including interleukin-4 (IL-4) and tumor necrosis factor-alpha (TNF-α). Gut microbiota composition was determined using 16 S rRNA gene sequencing, and the metabolomic profiling of intestinal samples was performed using gas chromatography-mass spectrometry to identify metabolites. BCEV treatment significantly alleviated skin lesions and reduced the serum IgE levels and the imbalance in IL-4 and TNF-α levels associated with AD induction. Gut microbiota analysis revealed that BCEVs restored microbial dysbiosis and improved the abundance of beneficial bacteria, and metabolomic analysis demonstrated elevated levels of lactic acid and other metabolites. These findings suggest that BCEVs alleviate AD symptoms by rebalancing the gut microbiota and intestinal metabolomes. This study emphasizes the importance of targeting the gut-skin axis as a novel strategy for AD treatment and provides evidence for the therapeutic potential of BCEVs in skin-related immune disorders.