Oral administration of Lactobacillus delbrueckii UFV-H2b20 protects mice against Aspergillus fumigatus lung infection.

Introduction: Probiotics provide therapeutic benefits not only in the gut but also other mucosal organs, including the lungs.

Objective and design: To evaluate the effects of the probiotic strain L. delbrueckii UFV-H2b20 oral administration in an experimental murine model of A. fumigatus pulmonary infection. BALB/c mice were associated with L. delbrueckii and infected with Aspergillus fumigatus and compared with non-associated group.

Methods: We investigated survival, respiratory mechanics, histopathology, colony forming units, cytokines in bronchoalveolar lavage, IgA in feces, efferocytosis, production of reactive oxygen species and the cell population in the mesenteric lymph nodes.

Results: L. delbrueckii induces tolerogenic dendritic cells, IL-10⁺macrophages and FoxP3⁺regulatory T cells in mesenteric lymph nodes and increased IgA levels in feces; after infection with A. fumigatus, increased survival and decreased fungal burden. There was decreased lung vascular permeability without changes in the leukocyte profile. There was enhanced neutrophilic response and increased macrophage efferocytosis. L. delbrueckii-treated mice displayed more of FoxP3⁺Treg cells, TGF-β and IL-10 levels in lungs, and concomitant decreased IL-1β, IL-17 A, and CXCL1 production.

Conclusion: Uur results indicate that L. delbrueckii UFV H2b20 ingestion improves immune responses, controlling pulmonary A. fumigatus infection. L. delbrueckii seems to play a role in pathogenesis control by promoting immune regulation.