Oral administration of recombinant Bacillus subtilis spores expressing Helicobacter pylori neutrophil‐activating protein suppresses peanut allergy via up‐regulation of Tregs

Abstract

Background Helicobacter pylori neutrophil‐activating protein (NAP) is an immune modulator with anti‐Th2 inflammation activity that can be used to prevent IgE‐mediated allergic reactions. Cholera toxin B (CTB) is a mucosal adjuvant that can induce antigen tolerance. Bacillus subtilis spores are an ideal vehicle for the oral delivery of heterologous antigens. Objective We investigated the therapeutic effect of recombinant NAP B subtilis spores on peanut allergies in a mouse model. Methods Female C3H/HeJ mice were sensitized and challenged with peanut extract by oral administration. Before challenge, recombinant NAP and CTB‐NAP (CNAP) spores were orally administered to sensitized mice for 4 weeks. Faecal peanut‐specific IgA and serum‐specific IgE, IgG1, and IgG2a levels were measured, and the intestinal microbiota was analysed. Mice were intraperitoneally injected with anti‐CD25 antibodies for regulatory T cell (Treg) depletion to evaluate the efficacy of Tregs in preventing peanut allergy. After challenge, anaphylactic reactions, plasma histamine, Tregs, and splenocyte interleukin (IL)‐10, IL‐4, IL‐5 and interferon‐γ (IFN‐γ) levels were evaluated. Results After 4 weeks of recombinant spore treatment, faecal IgA levels and serum IgG2a levels were increased, while serum IgG1 and IgE levels were reduced. Intestinal microbiota analysis revealed that CNAP spores increased the taxonomic abundance of Firmicutes at the phylum level and Clostridia at the class level. After challenge, the administration of NAP or CNAP spores to mice was found to ameliorate anaphylactic reactions and decrease plasma histamine levels. Administration of NAP or CNAP spores also enhanced IL‐10 and IFN‐γ secretion, and suppressed IL‐4 and IL‐5 secretion. The protective effect of CNAP spores was more pronounced than that of NAP spores; this therapeutic effect was lost after Treg depletion. Conclusions and Clinical Relevance Recombinant NAP spores successfully suppressed Th2 inflammation via the up‐regulation of Tregs; this may serve as a novel therapeutic approach for treating food allergies.

Alteration of Intestinal Microbiota Composition in Oral Sensitized C3H/HeJ Mice Is Associated With Changes in Dendritic Cells and T Cells in Mesenteric Lymph Nodes

“…In this study, C3H/HeJ mice showed extensive reactions, such as increased IgE, IgG1, and mMCP-1, and Th2-associated cytokine levels, decreased Treg populations in immune tissues, as well as decreased body temperature after OVA treatment without adjuvant. In previous researches, similarly, the C3H/HeJ strain mice also displayed obvious humoral immune reactions, cellular immune responses, and systemic allergy symptoms to ovomucoid (OM) (39), peanut (40)(41)(42), and fish allergens (43) by oral administration combined with cholera toxin (CT). The route and mechanism of CT influencing the intestine might be the same as those by which some bacteria act on the intestinal barrier, although the CT is not involved in the pathogenesis of food allergy itself (44,45).…”

Allergenicity Alleviation of Bee Pollen by Enzymatic Hydrolysis: Regulation in Mice Allergic Mediators, Metabolism, and Gut Microbiota

“…Its abundance was reduced in the gut microbiota of colitis mice but recovered following anti-inflammatory therapy [ 55 ]. Helicobacteraceae shows beneficial effects against food allergy, for instance, the neutrophil-activating protein of Helicobacter pylori can inhibit peanut allergy by up-regulating the production of Tregs [ 56 ]. The level of Bacillaceae is related to gut inflammatory diseases [ 57 ].…”

Oral administration of recombinant Bacillus subtilis spores expressing mutant staphylococcal enterotoxin B provides potent protection against lethal enterotoxin challenge

“…The recombinant plasmid was sequenced and transformed into B. subtilis WB600 cells. Sporulation of recombinant B. subtilis was induced via Difco sporulation medium (DSM) as previously described (Mai et al 2019 ). Spores were centrifuged at 8000 × g for 15 min, and the supernatant was removed.…”