AUTHOR=Smaldini Paola L. , Trejo Fernando M. , Rizzo Gastón P. , Comerci Diego J. , Kampinga Jaap , Docena Guillermo H. 

TITLE=Mucosal Immunoregulatory Properties of Tsukamurella inchonensis to Reverse Experimental Food Allergy

JOURNAL=Frontiers in Immunology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.641597

DOI=10.3389/fimmu.2021.641597

ISSN=1664-3224

ABSTRACT=The intestinal mucosa is lined by epithelial cells, which are key cells to sustain gut homeostasis. Food allergy is an immune-mediated adverse reaction to food, likely due to defective regulatory circuits. Tsukamurella inchonensis (Ti) is a non-pathogenic bacterium with immunomodulatory properties.  We hypothesize that the anti-inflammatory effect of dead Ti on activated epithelial cells can modulate milk allergy through the restoration of tolerance in a mouse model.

Epithelial cells (Caco-2 and enterocytes from mouse gut) and macrophages were stimulated with Ti and induction of luciferase under the NF-B promoter, ROS and cytokines were studied.  Balb/c mice were mucosally sensitized with cow´s milk proteins plus cholera toxin and orally challenged with the allergen to evidence hypersensitivity symptoms. Thereafter, mice were orally administered with heat-killed Ti as treatment and then challenged with the allergen. The therapeutic efficacy was in vivo (clinical score and cutaneous test) and in vitro (serum specific antibodies and cytokines-ELISA, and cell analysis-flow cytometry) evaluated.

Heat-killed Ti modulated the induction of pro-inflammatory chemokines, with an increase of anti-inflammatory cytokines by intestinal epithelial cells and by macrophages with decreased OX40L expression. In vivo, oral administration of Ti increased the frequency of lamina propria CD4+CD25+FoxP3+ T cells, and clinical signs were lower in Ti-treated mice compared with milk-sensitized animals. In vivo depletion of Tregs (anti-CD25) abrogated Ti immunomodulation. 

In conclusion, these bacteria modulate the NF-B pathway and the induction of OX40L to reverse experimental food allergy