Associate Professor Midwestern Univ., Downers Grove Downers Grove, Illinois, United States
Disclosure(s):
Julie Swartzendruber, PhD: No financial relationships to disclose
Introduction/Rationale: 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.
