BCL-2 Multi-Strain Probiotics for Immunomodulation In Vitro and In Vivo Alleviation of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory disorder with immune imbalance, including elevated IgE levels and mast cell activation mediated by Th2 cytokines, leading to allergic inflammation and impaired skin barrier function. Current treatment limitations highlight the need for safer and more effective AD alternatives. We aimed to evaluate the therapeutic effects of multi-strain probiotics, BCL-2 (comprising Lactiplantibacillus plantarum LRCC5264 and Bifidobacterium longum RAPO), in alleviating AD clinical signs and elucidate its underlying immunomodulatory mechanisms. In vitro, BCL-2 treatment significantly reduced IL-4 secretion in RBL-2H3 cells, with higher inhibitory effects than single-strain treatment. In vivo, BCL-2 (10⁶-10⁸ CFU/day) was orally administered for 28 days to AD-induced Nc/Nga mice. BCL-2 treatment improved the clinical signs and histopathological features of AD, including epidermal hypertrophy, hyperkeratosis, and mast cell infiltration (p < 0.05). It also reduced neutrophil and eosinophil counts and modulated cytokine and chemokine profiles, notably decreasing IL-17, IL-5, IL-6, TNF-α, IL-1β, TARC, and eotaxin, while increasing IL-10, IFN-γ, and IL-12 (p < 0.05). Among the tested concentrations, 10⁷ CFU exhibited the most effective immune modulation with no adverse effects on body weight. These findings demonstrate the therapeutic potential of BCL-2 in AD; however, further studies are required to validate its clinical relevance.