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Background: Approximately 70% of individuals allergic to birch pollen (Bet v 1.01 [Bet]) develop a secondary food allergy (e.g., hazelnut: Cor a 1.04 [Cor]), due to allergen cross‐reactivity. However, standard immunotherapy for type I allergies often does not improve the food allergy sufficiently. We analyzed the allergen‐specific and cross‐reactive suppressive capacity of primary human regulatory T cells (Treg) induced by autologous IL‐10‐modulated dendritic cells (IL‐10 DC) in vitro and in vivo. Methods: CD4+ T cells of patients with birch pollen and associated hazelnut allergies were differentiated into Bet‐specific or non‐specific induced Treg (iTreg). After Bet‐ or Cor‐specific restimulation the phenotype, proliferation, and suppressive capacity of iTreg subsets were analyzed. iTreg function was further investigated in humanized mouse models of airway and intestinal allergy, generated by engraftment of peripheral blood mononuclear cells from allergic donors into immunodeficient animals. Results: After IL‐10 DC priming and allergen‐specific restimulation (Bet or Cor), non‐specific control iTreg remained anergic, whereas Bet‐specific iTreg proliferated extensively and exhibited a regulatory phenotype (enhanced expression of CTLA‐4, PD‐1, TNFR2, IL‐10). Accordingly, activated Bet‐specific iTreg displayed a high capacity to suppress Bet‐ and Cor‐induced responder Th2 cell responses in vitro, indicating induction of both allergen‐specific (birch) and cross‐reactive tolerance (hazelnut). In vivo, the beneficial effect of Bet‐specific iTreg was verified in humanized mouse models of allergic airway and intestinal inflammation, resulting in reduced allergen‐induced clinical symptoms, and immune responses. Conclusion: Human IL‐10 DC‐induced iTreg facilitate allergen‐specific and cross‐reactive tolerance. Therefore, they are potential candidates for regulatory cell therapy in allergic and autoimmune diseases. [ABSTRACT FROM AUTHOR]

Background: The experimental fusion protein rFlaA:Betv1 was shown to efficiently suppress allergen‐specific sensitization in mice. However, the detailed mechanism of rFlaA:Betv1‐mediated immune modulation is not fully understood. In this study, we investigated the effect of rFlaA:Betv1 on naïve murine B cells. Methods: Immune modulating capacity of rFlaA:Betv1 was screened in IL‐10 reporter mice. B cells were isolated from spleens of naïve C57Bl/6, TLR5−/−, or MyD88−/− mice, stimulated with rFlaA:Betv1 and controls, and monitored for the expression of the regulatory B cell markers CD1d, CD24, CD38, and surface IgM by flow cytometry. Secreted cytokines, antibodies, and reactivity of the induced antibodies were investigated by ELISA and intracellular flow cytometry. Suppressive capacity of rFlaA:Betv1‐stimulated B cells was tested in mDC:CD4+ T cell:B cell triple cultures. Results: Upon in vivo application of rFlaA:Betv1 into IL‐10‐GFP reporter mice, CD19+ B cells were shown to produce anti‐inflammatory IL‐10, suggesting B cells to contribute to the immune‐modulatory properties of rFlaA:Betv1. rFlaA:Betv1‐induced IL‐10 secretion was confirmed in human B cells isolated from buffy coats. In vitro stimulation of naïve murine B cells with rFlaA:Betv1 resulted in an mTOR‐ and MyD88‐dependent production of IL‐10 and rFlaA:Betv1 induced Bet v 1‐reactive IgG production, which was not observed for IgA. rFlaA:Betv1‐stimulated B cells formed a CD19+CD24+CD1d+IgM+CD38+ Breg subpopulation capable of suppressing Bet v 1‐induced TH2 cytokine secretion in vitro. Conclusion: rFlaA:Betv1 can act as a thymus‐independent B cell antigen, stimulating the mTOR‐ and MyD88‐dependent differentiation of B cells displaying a regulatory phenotype, IL‐10 secretion, antigen‐binding antibody production, and a suppressive capacity in vitro. [ABSTRACT FROM AUTHOR]

However, celeriac allergic patients often show sensitization to mugwort defensin Art v 1 (Table S1).6 This prompted us to investigate the potential presence and role of a defensin-related allergen in allergy to celeriac. IgE-binding capacity and allergenicity of celeriac defensin (officially named Api g 7, www.allergen.org4) was investigated by immunoblotting and ImmunoCAP testing in eight celeriac allergic patients, two celeriac-tolerant controls with mugwort pollen allergy and a non-atopic control. Celeriac allergy is often accompanied by respiratory allergy to mugwort ( I Artemisia vulgaris i ) pollen,5 which cannot be explained by IgE cross-reactivity to known homologous celeriac allergens. [Extracted from the article]

Pectin, a dietary fiber, is a polysaccharide that is widely used in food industry as a gelling agent. In addition, prebiotic and beneficial immunomodulatory effects of pectin have been demonstrated, leading to increased importance as food supplement. However, as cases of anaphylactic reactions after consumption of pectin-supplemented foods have been reported, the present study aims to evaluate the allergy risk of pectin. This is of particular importance since most of the pectin used in the food industry is extracted from citrus or apple pomace. Both contain several allergens such as non-specific lipid transfer proteins (nsLTPs), known to induce severe allergic reactions, which could impair the use of pectins in nsLTP allergic patients. Therefore, the present study for the first time was performed to analyze residual nsLTP content in two commercial pectins using different detection methods. Results showed the analytical sensitivity was diminished by the pectin structure. Finally, spiking of pectin with allergenic peach nsLTP Pru p 3 led to the conclusion that the potential residual allergen content in both pectins is below the threshold to induce anaphylactic reactions in nsLTP-allergic patients. This data suggests that consumption of the investigated commercial pectin products provides no risk for inducing severe reactions in nsLTP-allergic patients. [ABSTRACT FROM AUTHOR]

Developing new adjuvants/vaccines and better understanding their mode-of-action is an important task. To specifically improve birch pollen allergy treatment, we designed a fusion protein consisting of major birch pollen allergen Betv1 conjugated to the TLR5-ligand flagellin (rFlaA:Betv1). This study investigates the immune-modulatory effects of rFlaA:Betv1 on airway epithelial cells. LA-4 mouse lung epithelial cells were stimulated with rFlaA:Betv1 in the presence/absence of various inhibitors with cytokine- and chemokine secretion quantified by ELISA and activation of intracellular signaling cascades demonstrated by Western blot (WB). Either LA-4 cells or LA-4-derived supernatants were co-cultured with BALB/c bone marrow-derived myeloid dendritic cells (mDCs). Compared to equimolar amounts of flagellin and Betv1 provided as a mixture, rFlaA:Betv1 induced higher secretion of IL-6 and the chemokines CCL2 and CCL20 from LA-4 cells and a pronounced MAPK- and NFκB-activation. Mechanistically, rFlaA:Betv1 was taken up more strongly and the induced cytokine production was inhibited by NFκB-inhibitors, while ERK- and p38-MAPK-inhibitors only suppressed IL-6 and CCL2 secretion. In co-cultures of LA-4 cells with mDCs, rFlaA:Betv1-stimulated LA-4 cells p38-MAPK- and COX2-dependently secreted PGE2, which modulated DC responses by suppressing pro-inflammatory IL-12 and TNF-α secretion. Taken together, these results contribute to our understanding of the mechanisms underlying the strong immune-modulatory effects of flagellin-containing fusion proteins. [ABSTRACT FROM AUTHOR]