Protective effect of the mixture of Lactiplantibacillus plantarum KC3 and Leonurus Japonicas Houtt extract on respiratory disorders

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Air pollutants, such as particulate matter (PM) and diesel exhaust particles (DEP), are associated with respiratory diseases. Therefore, preventive and therapeutic strategies against PM-and DEP (PM 10 D)-induced respiratory diseases are needed. Herein, we evaluate the protective effects of a mixture of Lactiplantibacillus plantarum KC3 and Leonurus Japonicas Houtt (LJH) extract against airway inflammation associated with exposure to PM 10 D. To determine the anti-inflammatory effects of the LJH extract, reactive oxygen species (ROS) production and the expression of inflammatory pathways were determined in PM 10 -induced MH-S cells. For the respiratory protective effects, BALB/c mice were exposed to PM 10 D via intranasal injection, and a mixture of L. plantarum KC3 and LJH extract was administered orally for 12 days. LJH extract inhibited ROS production and the phosphorylation of downstream factors of NF-κB in PM 10 -stimulated MH-S cells. The mixture of L. plantarum KC3 and LJH repressed the infiltration of neutrophils, reduced the immune cells number, and suppressed the proinflammatory mediators and cyclooxygenase (COX)-2 expressions in PM 10 D-induced airway inflammation with reduced phosphorylation of downstream factors of NF-κB. In addition, these effects were not observed in an alveolar macrophage depleted PM 10 D-induced mouse model using clodronate liposomes. The extract mixture also regulated gut microbiota in feces and upregulated the mRNA expression of Foxp3, transforming growth factor (TGF)-β1, and interleukin (IL)-10 in the colon. The L. plantarum KC3 and LJH extract mixture may inhibit alveolar macrophage- and neutrophil-mediated inflammatory responses and regulate gut microbiota and immune response in PM 10 D-induced airway inflammation, suggesting it is a potential remedy to prevent and cure airway inflammation and respiratory disorders. • LJH extract inhibited ROS production and NF-κB phosphorylation. • L. plantarum KC3 and LJH mixture inhibit airway immune and inflammatory responses. • L. plantarum KC3 and LJH mixture regulate gut microbiota and immune response in colon. • L. plantarum KC3 and LJH mixture as a potential remedy to treat airway inflammation.