Saccharomyces cerevisiae UFMG A-905 acts in an animal model of asthma by modulating Th17/Treg responses and increasing fatty acid production

BACKGROUND: Asthma prevalence has been increasing, particularly among children and in populations transitioning to Western lifestyle. According to the hygiene hypothesis, early-life exposure to microorganisms may protect against asthma and other allergic conditions. Previous studies demonstrated that Saccharomyces cerevisiae UFMG A-905 reduce bronchial hyperresponsiveness, airway and lung inflammation, and restore IL-10 and IFN-γ. However, the underlying mechanisms remain unclear. OBJECTIVE: To investigate the potential pathways by which S. cerevisiae UFMG A-905 modulates asthma. MATERIALS AND METHODS: Wild-type and Il17a⁻/⁻ mice were treated daily with live yeast or its supernatant (postbiotic) by oral gavage, starting ten days before OVA sensitization and maintained during sensitization and challenge. Control groups received saline. Lung tissues were analyzed by flow cytometry to assess dendritic cells and regulatory T cells. Gene expression of TLR-9, NLRP3, Dectin-1, and Mincle was quantified by qPCR. Short-, medium-, and long-chain fatty acids were measured in feces using gas chromatography, while gut cytokine were evaluated by ELISA. RESULTS: Treatment with S. cerevisiae UFMG A-905 led to an increase in CD11c⁺MHCII⁺CD11b⁺CD103⁻ dendritic cells, regulatory T cells (CD4⁺CD25⁺FOXP3⁺), and NLRP3 gene expression in the lung, and the fecal levels of dihomo-γ-linolenic acid. Neither gut cytokines nor OVA specific IgE were affected, and the supernatant did not significantly alter cell counts. The beneficial effects were partially dependent on IL-17A. CONCLUSION: The effects observed with S. cerevisiae UFMG A-905 correlated with modulation of Th17, dendritic-cell and regulatory T-cell responses, upregulation of NLRP3, and increased fatty acid production, suggesting gut-lung axis involvement.