Airway inflammation induced after allergic poly-sensitization can be prevented by mucosal but not by systemic administration of poly-peptides

Pre- and Neonatal Imprinting on Immunological Homeostasis and Epithelial Barrier Integrity by Escherichia coli Nissle 1917 Prevents Allergic Poly-Sensitization in Mice

A steady rise in the number of poly-sensitized patients has increased the demand for effective prophylactic strategies against multi-sensitivities. Probiotic bacteria have been successfully used in clinics and experimental models to prevent allergic mono-sensitization. In the present study, we have investigated whether probiotic bacteria could prevent poly-sensitization by imprinting on the immune system early in life. We used two recombinant variants of probiotic Escherichia coli Nissle 1917 (EcN): i) EcN expressing birch and grass pollen, poly-allergen chimera construct (EcN-Chim), and ii) an “empty” EcN without allergen expression (EcN-Ctrl). Conventional mice (CV) were treated with either EcN-Chim or EcN-Ctrl in the last week of the gestation and lactation period. Gnotobiotic mice received one oral dose of either EcN-Chim or EcN-Ctrl before mating. The offspring from both models underwent systemic allergic poly-sensitization and intranasal challenge with recombinant birch and grass pollen allergens (rBet v 1, rPhl p 1, and rPhl p 5). In the CV setting, the colonization of offspring via treatment of mothers reduced allergic airway inflammation (AAI) in offspring compared to poly-sensitized controls. Similarly, in a gnotobiotic model, AAI was reduced in EcN-Chim and EcN-Ctrl mono-colonized offspring. However, allergy prevention was more pronounced in the EcN-Ctrl mono-colonized offspring as compared to EcN-Chim. Mono-colonization with EcN-Ctrl was associated with a shift toward mixed Th1/Treg immune responses, increased expression of TLR2 and TLR4 in the lung, and maintained levels of zonulin-1 in lung epithelial cells as compared to GF poly-sensitized and EcN-Chim mono-colonized mice. This study is the first one to establish the model of allergic poly-sensitization in gnotobiotic mice. Using two different settings, gnotobiotic and conventional mice, we demonstrated that an early life intervention with the EcN without expressing an allergen is a powerful strategy to prevent poly-sensitization later in life.

E. coli Nissle 1917 is a safe mucosal delivery vector for a birch-grass pollen chimera to prevent allergic poly-sensitization

Allergic poly-sensitization affects a large number of allergic patients and poses a great challenge for their treatment. In this study we evaluated the effects of the probiotic Escherichia coli Nissle 1917 (EcN) expressing a birch and grass pollen allergen chimera 'Bet v 1, Phl p 1 and Phl p 5' (EcN-Chim) on allergy prevention after oral or intranasal application in poly-sensitized mice. In contrast to oral application, intranasal pretreatment with EcN-Chim prior to poly-sensitization led to a significant reduction of lung inflammation (eosinophils, IL-5, and IL-13 in bronchoalveolar lavage) along with suppressed levels of allergen-specific serum IgE. The suppression was associated with increased levels of allergen-specific IgA in lungs and serum IgG2a along with increased Foxp3, TGF-β, and IL-10 mRNA in bronchial lymph nodes. In vitro EcN induced high levels of IL-10 and IL-6 in both lung and intestinal epithelial cells. Importantly, using in vivo imaging techniques we demonstrated that intranasally applied EcN do not permanently colonize nose, lung, and gut and this strain might therefore be a safe delivery vector against allergy in humans. In conclusion, our data show that intranasal application of recombinant EcN expressing a multiallergen chimera presents a novel and promising treatment strategy for prevention of allergic poly-sensitization.

Murine models for mucosal tolerance in allergy

Immunity is established by a fine balance to discriminate between self and non-self. In addition, mucosal surfaces have the unique ability to establish and maintain a state of tolerance also against non-self constituents such as those represented by the large numbers of commensals populating mucosal surfaces and food-derived or air-borne antigens. Recent years have seen a dramatic expansion in our understanding of the basic mechanisms and the involved cellular and molecular players orchestrating mucosal tolerance. As a direct outgrowth, promising prophylactic and therapeutic models for mucosal tolerance induction against usually innocuous antigens (derived from food and aeroallergen sources) have been developed. A major theme in the past years was the introduction of improved formulations and novel adjuvants into such allergy vaccines. This review article describes basic mechanisms of mucosal tolerance induction and contrasts the peculiarities but also the interdependence of the gut and respiratory tract associated lymphoid tissues in that context. Particular emphasis is put on delineating the current prophylactic and therapeutic strategies to study and improve mucosal tolerance induction in allergy.

New Routes of Allergen Immunotherapy

Objectives

Allergen immunotherapy is the only cure for immunoglobulin E mediated type I respiratory allergies. Subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) are the most common treatments. In this article, we reviewed new routes of allergen immunotherapy.

Methods

Data on alternative routes to allow intralymphatic immunotherapy (ILIT), epicutaneous immunotherapy (EPIT), local nasal immunotherapy (LNIT), oral immunotherapy (OIT), and oral mucosal immunotherapy (OMIT) were gathered from the literature and were discussed.

Results

ILIT features direct injection of allergens into lymph nodes. ILIT may be clinically effective after only a few injections and induces allergen-specific immunoglobulin G, similarly to SCIT. A limitation of ILIT is that intralymphatic injections are required. EPIT features allergen administration by using patches mounted on the skin. EPIT seeks to target epidermal antigen–presenting Langerhans cells rather than mast cells or the vasculature; this should reduce both local and systemic adverse effects. LNIT involves the spraying of allergen extracts into the nasal cavity. Natural or chemically modified allergens (the latter, termed allergoids, lack immunoglobulin E reactivity) are prepared in a soluble form. OIT involves the regular administration of small amounts of a food allergen by mouth and commences with low oral doses, which are then increased as tolerance develops. OMIT seeks to deliver allergenic proteins to an expanded population of Langerhans cells in the mucosa of the oral cavity.

Conclusions

ILIT, EPIT, LNIT, OIT, and OMIT are new routes for allergen immunotherapy. They are safe and effective.

The Role of Alveolar Epithelial Type II-Like Cells in Uptake of Structurally Different Antigens and in Polarisation of Local Immune Responses

Background

Our previous studies on intranasal tolerance induction demonstrated reduction of allergic responses with different allergen constructs. The underlying mechanisms varied depending on their conformation or size.

Objective

The aim of the present study was to compare the uptake of two structurally different allergen molecules within the respiratory tract following intranasal application.

Methods

The three-dimensional Bet v 1 (Bv1-Protein) and the T cell epitope peptide of Bet v 1 (Bv1-Peptide) were labelled with 5,6-Carboxyfluorescein (FAM) and their uptake was investigated in lung cells and cells of the nasal associated lymphoid tissue from naive and sensitised BALB/c mice. Phenotypic characterisation of FAM⁺ lung cells after antigen incubation in vitro and after intranasal application was performed by flow cytometry. Impact of Bv1-Protein and Bv1-Peptide on cytokine profiles and gene expression in vivo or in an alveolar epithelial type II (ATII) cell line were assessed in mono- and co-cultures with monocytes using ELISA and quantitative real-time PCR.

Results

Both antigens were taken up preferably by ATII-like cells (ATII-LCs) in naive mice, and by macrophages in sensitised mice. After intranasal application, Bv1-Peptide was taken up faster and more efficiently than Bv1-Protein. In vivo and in vitro experiments revealed that Bv1-Protein induced the transcription of thymic stromal lymphopoietin mRNA while Bv1-Peptide induced the transcription of IL-10 and MCP1 mRNA in ATII-LCs.

Conclusion and Clinical Relevance

Both tested antigens were taken up by ATII-LCs under steady state conditions and induced different polarisation of the immune responses. These data may have an important impact for the generation of novel and more effective prophylactic or therapeutic tools targeting the respiratory mucosa.

Prevention of birch pollen-related food allergy by mucosal treatment with multi-allergen-chimers in mice

Background

Among birch pollen allergic patients up to 70% develop allergic reactions to Bet v 1-homologue food allergens such as Api g 1 (celery) or Dau c 1 (carrot), termed as birch pollen-related food allergy. In most cases, specific immunotherapy with birch pollen extracts does not reduce allergic symptoms to the homologue food allergens. We therefore genetically engineered a multi-allergen chimer and tested if mucosal treatment with this construct could represent a novel approach for prevention of birch pollen-related food allergy.

Methodology

BALB/c mice were poly-sensitized with a mixture of Bet v 1, Api g 1 and Dau c 1 followed by a sublingual challenge with carrot, celery and birch pollen extracts. For prevention of allergy sensitization an allergen chimer composed of immunodominant T cell epitopes of Api g 1 and Dau c 1 linked to the whole Bet v 1 allergen, was intranasally applied prior to sensitization.

Results

Intranasal pretreatment with the allergen chimer led to significantly decreased antigen-specific IgE-dependent β-hexosaminidase release, but enhanced allergen-specific IgG2a and IgA antibodies. Accordingly, IL-4 levels in spleen cell cultures and IL-5 levels in restimulated spleen and cervical lymph node cell cultures were markedly reduced, while IFN-γ levels were increased. Immunomodulation was associated with increased IL-10, TGF-β and Foxp3 mRNA levels in NALT and Foxp3 in oral mucosal tissues. Treatment with anti-TGF-β, anti-IL10R or anti-CD25 antibodies abrogated the suppression of allergic responses induced by the chimer.

Conclusion

Our results indicate that mucosal application of the allergen chimer led to decreased Th2 immune responses against Bet v 1 and its homologue food allergens Api g 1 and Dau c 1 by regulatory and Th1-biased immune responses. These data suggest that mucosal treatment with a multi-allergen vaccine could be a promising treatment strategy to prevent birch pollen-related food allergy.

Novel routes for allergen immunotherapy: safety, efficacy and mode of action

Allergen immunotherapy is the only curative treatment of IgE-mediated type I respiratory allergies. Subcutaneous immunotherapy (SCIT) is used as a reference therapy and has transformed allergic treatments; it improves symptoms (asthma and rhinitis) as well as the quality of life of patients. SCIT requires repetitive administration and carries the risk of severe systemic adverse effects, including anaphylaxis. Sublingual immunotherapy is now a valid noninvasive alternative to SCIT, as a safe and efficacious treatment for respiratory allergies. In this article, we compare various routes of allergen immunotherapy, including SCIT and sublingual immunotherapy, as well as more exploratory routes currently under investigation (i.e., intralymphatic, epicutaneous, intranasal and oral). We discuss their respective advantages, as well as their foreseen modes of action.

Oral macrophage-like cells play a key role in tolerance induction following sublingual immunotherapy of asthmatic mice

Sublingual allergen-specific immunotherapy (SLIT) is a safe and efficacious treatment for type 1 respiratory allergies. Herein, we investigated the key subset(s) of antigen-presenting cells (APCs) involved in antigen/allergen capture and tolerance induction during SLIT. Following sublingual administration, fluorochrome-labeled ovalbumin (OVA) is predominantly captured by oral CD11b⁺CD11c⁻ cells that migrate to cervical lymph nodes (CLNs) and present the antigen to naive CD4⁺ T cells. Conditional depletion with diphtheria toxin of CD11b⁺, but not CD11c⁺ cells, in oral tissues impairs CD4⁺ T-cell priming in CLNs. In mice with established asthma to OVA, specific targeting of the antigen to oral CD11b⁺ cells using the adenylate cyclase vector system reduces airway hyperresponsiveness (AHR), eosinophil recruitment in bronchoalveolar lavages (BALs), and specific Th2 responses in CLNs and lungs. Oral CD11b⁺CD11c⁻ cells resemble tolerogenic macrophages found in the lamina propria (LP) of the small intestine in that they express the mannose receptor CD206, as well as class-2 retinaldehyde dehydrogenase (RALDH2), and they support the differentiation of interferon-γ/interleukin-10 (IFNγ/IL-10)-producing Foxp3⁺ CD4⁺ regulatory T cells. Thus, among the various APC subsets present in oral tissues of mice, macrophage-like cells play a key role in tolerance induction following SLIT.

Strategies of mucosal immunotherapy for allergic diseases

Incidences of allergic disease have recently increased worldwide. Allergen-specific immunotherapy (SIT) has long been a controversial treatment for allergic diseases. Although beneficial effects on clinically relevant outcomes have been demonstrated in clinical trials by subcutaneous immunotherapy (SCIT), there remains a risk of severe and sometimes fatal anaphylaxis. Mucosal immunotherapy is one advantageous choice because of its non-injection routes of administration and lower side-effect profile. This study reviews recent progress in mucosal immunotherapy for allergic diseases. Administration routes, antigen quality and quantity, and adjuvants used are major considerations in this field. Also, direct uses of unique probiotics, or specific cytokines, have been discussed. Furthermore, some researchers have reported new therapeutic ideas that combine two or more strategies. The most important strategy for development of mucosal therapies for allergic diseases is the improvement of antigen formulation, which includes continuous searching for efficient adjuvants, collecting more information about dominant T-cell epitopes of allergens, and having the proper combination of each. In clinics, when compared to other mucosal routes, sublingual immunotherapy (SLIT) is a preferred choice for therapeutic administration, although local and systemic side effects have been reported. Additionally, not every allergen has the same beneficial effect. Further studies are needed to determine the benefits of mucosal immunotherapy for different allergic diseases after comparison of the different administration routes in children and adults. Data collected from large, well-designed, double-blind, placebo-controlled, and randomized trials, with post-treatment follow-up, can provide robust substantiation of current evidence.

Cell-based therapy in allergy

IgE-mediated allergy is an immunological disorder occurring in response to otherwise harmless environmental antigens (i.e., allergens). Development of effective therapeutic or preventive approaches inducing robust tolerance toward allergens remains an unmet goal. Several experimental tolerance approaches have been described. The therapeutic use of regulatory T cells (Tregs) and the establishment of molecular chimerism are two cell-based strategies that are of particular interest. Treg therapy is close to clinical application, but its efficacy remains to be fully defined. Recent proof-of-concept studies demonstrated that transplantation of syngeneic hematopoietic stem cells modified in vitro to express a major allergen leads to molecular chimerism and robust allergen-specific tolerance. Here we review cell-based tolerance strategies in allergy, discussing their potentials and limitations.

Developments in the field of allergy in 2008 through the eyes of Clinical & Experimental Allergy

In 2008, many thousands of articles were published on the subject of allergic disease with over 200 reviews, editorials and original papers in Clinical & Experimental Allergy alone. These represent a considerable amount of data and even the most avid reader could only hope to assimilate a small fraction of this knowledge. There is therefore a pressing need for the key messages that emerge from a journal such as Clinical & Experimental Allergy to be summarized by experts in the field in a form that highlights the significance of the developments and sets them in the context of important findings in the field published in other journals. This also has the advantage of making connections between new data in conditions such as asthma, where articles often appear in different sections of the journal. As can be seen from this review, the body of work is diverse both in terms of the disease of interest and the discipline that has been used to investigate it. However, taken as a whole, we hope that the reader will gain a flavour of where the field is mature, where there remain controversies and where the cutting edge is leading.