Probiotic consumption alleviates atopic dermatitis-related immune responses in association with gut microbial changes: In vitro and mouse model studies

This study investigates the potential of novel probiotic strains, a 1:1 mix of Bifidobacterium longum RAPO and Lactiplantibacillus plantarum LRCC5264, to alleviate atopic dermatitis (AD). In vitro, the probiotics at 1 × 106 CFU/mL increased anti-inflammatory (interleukin-6; IL6) and reduced pro-inflammatory (IL9) cytokine expression in LPS-stimulated RAW 264.7 cells. In an 2,4-dinitrochlorobenzene-induced AD mouse model, treatment with the probiotics (1 × 106 CFU/day) for eight weeks exhibited significant reductions in dermatitis score, plasma immunoglobulin E, transepidermal water loss, and mRNA expression of ceramidase in the skin. Furthermore, the probiotic consumption suppressed Il9 mRNA expression in the skin and reduced eotaxin-1, eosinophil infiltration, and epidermal thickness. Gut microbiota analysis revealed probiotic consumption increased relative abundances of Alistipes and Ruminococcaceae_uncultured, with a negative association with immune responses and skin barrier functions. These results demonstrate the potential of the probiotic strains in modulating immune responses and the gut microbiota, suggesting their role as a dietary intervention strategy for managing AD.