Rationale: Probiotics have been shown to be effective in reducing allergic symptoms. However, there are few studies to evaluate the therapeutic effects of lactobacilli on allergen-induced airway inflammation.
Objective: We investigated whether three heat-killed lactobacilli, Lactobacillus plantarum, Lactobacillus curvatus and Lactobacillus sakei subsp. sakei, isolated from kimchi, exerted inhibitory effects on airway hyper-responsiveness in a murine asthma model.
Methods: Heat-killed lactic acid bacteria were orally administered into BALB/c mice, followed by challenge with aerosolized ovalbumin, after which allergic symptoms were evaluated.
Results: Airway inflammation was suppressed in the L. plantarum- and L. curvatus-treated mice. Interleukin (IL)-4 and IL-5 levels were significantly lower in the L. plantarum- and L. curvatus-treated mice than in those treated with L. sakei subsp. sakei. Importantly, heat-killed L. plantarum administration induced Foxp3 expression in intestinal lamina propria cells, and heat-killed L. curvatus induced IL-10 as a way of inducing tolerance.
Conclusion: Specific strains of lactobacilli isolated from kimchi can effectively suppress airway hyper-responsiveness.