Bacillus clausii, a Foreshore-Derived Probiotic, Attenuates Allergic Airway Inflammation Through Downregulation of Hypoxia Signaling

ABSTRACT

Background and Objectives@#The immunomodulatory effects and mechanism of probiotics in allergic airway disease are largely unknown. We studied whether Bacillus clausii (BC), a probiotic derived from mudflats, had anti-allergic effects and compared the results with those of Lactobacillus paracasei (LP). We also examined whether the anti-allergic mechanisms of probiotics are associated with hypoxia signaling.Materials and Method: Forty-two BALB/c mice were randomly assigned to six experimental groups controls, ovalbumin (OVA)-induced mice for inducing asthma, and OVA-induced mice that were orally administered LP or BC, at 1×109 or 5×109 CFU/mL each. We performed differential cell count testing on bronchoalveolar lavage fluid (BALF), lung histopathology, serum totals and OVA-specific IgE and IgG1 assessments, Th2 cytokine titers (IL-4, IL-5) in BALF and pulmonary parenchyma, quantitative PCR for heme oxygenase (HO)-1 and Hif-1α, and immunohistochemistry. @*Results@#Compared to the OVA group mice, OVA-sensitized mice treated with LP or BC showed significantly reduced numbers of eosinophils and neutrophils in the BALF (p<0.05). Both probiotics also significantly reduced pulmonary inflammation and eosinophil infiltration. Mice in the LP or BC group had a substantially lower titer of IL-4 and IL-5 in BALF, and decreased IL-4 and IL-5 expression in the lung parenchyma. Real-time PCR and immunohistochemistry showed that both LP and BC could significantly suppress HO-1 and Hif-1α expression in asthmatic mice (p<0.05). @*Conclusion@#BC can attenuate murine allergic asthma by regulating HIF-1α signaling, and its anti-allergic effect is comparable to that of LP.