Oral Administration of Heat-Inactivated Lactobacillus plantarum K37 Modulated Airway Hyperresponsiveness in Ovalbumin-Sensitized BALB/c Mice

This study aimed to investigate the anti-allergic effects of Lactobacillus plantarum K37 (K37) on airway hyperresponsiveness (AHR) and systemic allergic responses in ovalbumin (OVA)-sensitized and -challenged BALB/c mice. Heat-inactivated K37 (10(5), 10(7), and 10(9) CFU/mouse, day) were orally administered to OVA-sensitized BALB/c mice to investigate their effects on AHR, immunoglobulin (Ig) and cytokine production. The results showed that K37 dose-dependently lowered the serum levels of IgE, OVA-specific IgE and OVA-specific IgG1, ameliorated AHR induced by methacholine and suppressed eosinophil infiltration in bronchoalveolar lavage fluid (BALF). The cytokine production in spleen cells culture and BALF showed that K37 drove the immune responses toward T-helper cell type 1 (Th1) responses, elevated levels of IL-2 and IFN-γ, and reduced of IL-4, IL-5 and IL-13. K37 also improved cell infiltration in lung sections. Our results demonstrated that oral administration of K37 alleviated effectively the allergic responses in vivo. Thus, K37 can be a good source material and a promising candidate for prophylactic and therapeutic treatments of allergic diseases, like asthma.