Human milk-derived Bifidobacterium longum subsp. infantis CCFM1269 alleviates food allergy by modulating gut microbiota and restoring intestinal barrier.

Food allergy (FA) is an immune-mediated disorder increasingly linked to intestinal dysbiosis and epithelial barrier dysfunction. This study evaluated the protective effects of Bifidobacterium longum subsp. infantis CCFM1269, a human milk-derived probiotic, using a β-lactoglobulin-induced FA mouse model. Oral administration of CCFM1269 significantly reduced allergic symptoms, including poor weight gain, diarrhea, and elevated allergy scores. The probiotic restored immune balance by downregulating IL-4 and IL-17 A and upregulating IL-10 and IFN-γ in both serum and jejunal tissues. It also alleviated oxidative stress by increasing superoxide dismutase activity and decreasing malondialdehyde levels. CCFM1269 enhanced intestinal barrier integrity through the upregulation of tight junction proteins Occludin, Claudin-1, and ZO-1. Microbiome analysis showed that CCFM1269 reshaped the gut microbial structure by increasing Helicobacter and reducing Alloprevotella and Bacteroides, taxa strongly associated with FA severity. Correlation analysis confirmed that these microbial changes were linked to improvements in immune and barrier function. Collectively, these findings indicate that human milk-derived CCFM1269 alleviates FA through microbiota modulation and epithelial restoration, supporting its potential as a probiotic strategy for preventing and treating FA.