Probiotics Attenuates Allergic Airway Inflammation via Downregulation of Hypoxia Signaling

Abstract

A recent study showed probiotics had been advocated for the prevention and treatment of allergic disease. However, the immunomodulatory effects and mechanism of probiotics on allergic airway disease such as asthma are unknown. This study investigated whether oral administrations of probiotics inhibited allergen-induced airway inflammation in a mouse asthma model. BALB/c mice were randomly assigned to the six experimental groups: controls; OVA-induced asthmatic mice; and OVA-induced mice orally administered with one of the two probiotics (Lactobacillus paracasei or Bacillus clausii, dose of 1×106 or 5×106 CFU, respectively). Effects of treatment were analyzed based on serum antibody levels, bronchoalveolar lavage fluids (BALF) cell counts, lung histology, lung cytokine levels, and airway hyperreactivity (AHR). OVA-sensitized mice treated with probiotics had significantly reduced numbers of eosinophils and total cell in BALF compared to the OVA group (p<0.05). Probiotics also significantly reduced eosinophil infiltration, which decreased AHR and inflammation in the lung tissues of OVA-sensitized mice. Probiotics also decreased the levels of Th2 cytokines in BALF. A real-time PCR analysis of the expression of genes in lung tissues showed that probiotics could significantly decrease the levels of HO-1 and HIF-1α expression compared to the levels in asthmatic mice (p<0.05). These results indicate that probiotics attenuate airway inflammation and hyperresponsiveness by regulating HIF-1α signaling in allergic airway disease. This finding suggests that probiotics have a role in the progress of the allergic disease, and might be used as a therapeutic tool of allergic airway inflammation.