Mucosal Immunoregulatory Properties of Tsukamurella inchonensis to Reverse Experimental Food Allergy.

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

doi:10.3389/fimmu.2021.641597

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 is a non-pathogenic bacterium with immunomodulatory properties. We hypothesize that the anti-inflammatory effect of dead T. inchonensis on activated epithelial cells modulates 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 T. inchonensis and induction of luciferase under the NF-κB promoter, ROS and cytokines production 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. After that, mice were orally administered with heat-killed T. inchonensis 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 T. inchonensis modulated the induction of pro-inflammatory chemokines, with an increase in anti-inflammatory cytokines by intestinal epithelial cells and by macrophages with decreased OX40L expression. In vivo, oral administration of T. inchonensis increased the frequency of lamina propria CD4+CD25+FoxP3+ T cells, and clinical signs were lower in T. inchonensis-treated mice compared with milk-sensitized animals. In vivo depletion of Tregs (anti-CD25) abrogated T. inchonensis immunomodulation. In conclusion, these bacteria suppressed the intestinal inflammatory immune response to reverse food allergy.

Highlights

Cow’s milk allergy (CMA) is an immunological mediated reaction to cow’s milk proteins and one of the most prevalent human food allergies, in infants and young children [1]
We first examined the effect of Tsukamurella inchonensis (Ti) on intestinal epithelial cells, and we observed that heat-killed Ti did not activate the reporter Caco-2 luciferase cell line, whereas it significantly suppressed the FliC-induced NF-kB-dependent cell activation
We assessed the production of regulatory cytokines on a primary mouse intestinal epithelial cells, and we found that IL-10 and TGF-b were secreted (p

Summary

Introduction

Cow’s milk allergy (CMA) is an immunological mediated reaction to cow’s milk proteins and one of the most prevalent human food allergies, in infants and young children [1]. Evidence of a lack of oral tolerance in food allergic patients [2, 3] has increased the interest in oral immunotherapy (OIT) as an option for disease-modifying therapy. Palforzia is the only immunotherapy approved for food allergies. It has proved to raise the threshold at which an allergic individual will react to accidental exposure to peanut (https://www.fda.gov/newsevents/press-announcements/fda-approves-first-drugtreatment-peanut-allergy-children). We and others demonstrated that the adoptive transfer of CD4+CD25+ regulatory T cells suppressed food allergy and the eosinophilia induced by the exposure to a specific antigen in the gut and airways, respectively [6, 7]. It has been described that patients with mutations in FoxP3 (Immune dysregulation, polyendocrinopathy, enteropathy syndrome or IPEX) have no regulatory T cells. Patients suffer from a generalized autoimmune enteropathy after birth, with high IgE levels and eosinophilia, accompanied by thyroiditis, type I diabetes, severe eczema, gastrointestinal disorders, etc

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Conclusion