Oral Bacillus subtilis modulates immune responses and reduces clinical symptoms in a murine model of atopic dermatitis 2260134

Abstract Introduction Allergic diseases like atopic dermatitis (AD) have risen with modern lifestyle changes affecting the microbiome. AD involves skin barrier dysfunction and immune dysregulation. Bacillus subtilis is Gram-positive bacterium that has been shown in a variety of inflammatory diseases to suppress inflammation. This study shows oral Bacillus subtilis protects against House Dust Mite (HDM)-induced AD by reducing clinical symptoms, epidermal thickness, mast cells, and increasing immunoglobulin A (IgA) and intestinal regulatory T cells (Tregs). Methods BALB/c mice received oral Bacillus subtilis or PBS and topical HDM to induce AD. Disease severity was assessed using clinical scoring, H&E staining for epidermal thickness, Toluidine Blue for mast cell infiltration, and ELISA for total and HDM-specific Immunoglobulins. Multiplex and ELISA were used for serum analysis. Flow Cytometry and RT-PCR were used to analyze Tregs. Results Bacillus subtilis treatment reduced clinical symptoms in a murine model of atopic dermatitis. Mice receiving B. subtilis showed lower lesion scores at weeks 3 and 7. While epidermal thickness and Th2-associated antibodies (IgG1, IgE) were unaffected, total IgA increased with B. subtilis treatment. B. subtilis prevented mast cell accumulation in HDM-induced lesions, and elevated intestinal Tregs expressing GATA3 and IL-10. Conclusion Oral administration of B. subtilis reduced clinical symptoms in HDM-induced atopic dermatitis. Protection occurred without lowering IgE or IgG1 but correlated with increased IgA and gut Tregs expressing IL-10 and GATA3. This study supports the value of beneficial microbes for preventing the development of atopic disease, and sheds light on the importance of the gut-skin axis. Funding Source n/a Topic Categories Mucosal and Regional Immunology (MUC)