AHR and allergic asthma: Probiotics use major mechanisms to improve allergic asthma clinical symptoms and prevent them, with several known mechanisms: Th2 suppression and shift response to Th1, tolerance induction, increase of IL-10, Treg cells and their responses for control immune-inflammation, increase the IFN-γ/IL-4 ratio, decrease eosinophil, Th2 cytokines and IgE levels, reduce gene expression of allegro-immune response related, chemokines and cytokines signaling pathways, and also, control AHR.