Oral administration of Lactobacillus delbrueckii subsp. lactis LDL557 attenuates airway inflammation and changes the gut microbiota in a Der p-sensitized mouse model of allergic asthma.

Background: Lactic acid bacteria may be used as probiotics to prevent or treat various diseases, and Lactobacillus delbrueckii has an inhibitory effect on the development of atopic diseases.

Objective: This study explored the effects of L. delbrueckii subsp. lactis strain LDL557 administration on a mouse asthma model resulting from Dermatophoides pteronyssinus (Der p) sensitization and investigated the associated gut microbiota.

Methods: Der p-sensitized and challenged BALB/c mice were orally administered with three different doses of live (low, 10⁷ colony-forming units (CFU); medium, 10⁸ CFU; high, 10⁹ CFU) and heat-killed (10⁹ cells) LDL557 in 200 μL of PBS daily, starting 2 weeks before Der p sensitization and lasting 4 weeks. After the allergen challenge, airway responsiveness to methacholine and the influx of inflammatory cells to the lungs were assessed. The gut microbiome was obtained by sequencing the V3-V4 region of the 16S rRNA gene from mice stool samples.

Results: LDL557 in the live (10⁹ CFU) and heat-killed (10⁹ cells) conditions reduced the airway hyper-responsiveness after stimulation with methacholine, inflammatory cell infiltration, and mucus production. These effects were similar to those in groups treated with dexamethasone. No significant change in the gut microbiota was observed after LDL557 treatment, except for the tendency of heat-killed LDL557 to change the gut microbial profile to a greater extent than live LDL557.

Conclusion: In summary, we found that live and heat-killed LDL557 had the beneficial effect of preventing Der p-induced allergic inflammation in a mouse model of asthma.