Outstanding animal studies in allergy II. From atopic barrier and microbiome to allergen-specific immunotherapy

Inhibition of pathologic immunoglobulin E in food allergy by EBF-2 and active compound berberine associated with immunometabolism regulation

Introduction

Food allergy is a significant public health problem with limited treatment options. As Food Allergy Herbal Formula 2 (FAHF-2) showed potential as a food allergy treatment, we further developed a purified version named EBF-2 and identified active compounds. We investigated the mechanisms of EBF-2 on IgE-mediated peanut (PN) allergy and its active compound, berberine, on IgE production.

Methods

IgE plasma cell line U266 cells were cultured with EBF-2 and FAHF-2, and their effects on IgE production were compared. EBF-2 was evaluated in a murine PN allergy model for its effect on PN-specific IgE production, number of IgE⁺ plasma cells, and PN anaphylaxis. Effects of berberine on IgE production, the expression of transcription factors, and mitochondrial glucose metabolism in U266 cells were evaluated.

Results

EBF-2 dose-dependently suppressed IgE production and was over 16 times more potent than FAHF-2 in IgE suppression in U266 cells. EBF-2 significantly suppressed PN-specific IgE production (70%, p<0.001) and the number of IgE-producing plasma cells in PN allergic mice, accompanied by 100% inhibition of PN-induced anaphylaxis and plasma histamine release (p<0.001) without affecting IgG1 or IgG2a production. Berberine markedly suppressed IgE production, which was associated with suppression of XBP1, BLIMP1, and STAT6 transcription factors and a reduced rate of mitochondrial oxidation in an IgE-producing plasma cell line.

Conclusions

EBF-2 and its active compound berberine are potent IgE suppressors, associated with cellular regulation of immunometabolism on IgE plasma cells, and may be a potential therapy for IgE-mediated food allergy and other allergic disorders.

The Microbiome as a Gateway to Prevention of Allergic Disease Development

Allergic diseases exclusively affect tissues that face environmental challenges and harbor endogenous bacterial microbiota. The microbes inhabiting the affected tissues may not be mere bystanders in this process but actively affect the risk of allergic sensitization, disease development, and exacerbation or abatement of symptoms. Experimental evidence provides several plausible means by which the human microbiota could influence the development of allergic diseases including, but not limited to, effects on antigen presentation and induction of tolerance and allergen permeation by endorsing or disrupting epithelial barrier integrity. Epidemiological evidence attests to the significance of age-appropriate, nonpathogenic microbiota development in skin, gastrointestinal tract, and airways for protection against allergic disease development. Thus, there exist potential targets for preventive actions either in the prenatal or postnatal period. These could include maternal dietary interventions, antibiotic stewardship for both the mother and infant, reducing elective cesarean deliveries, and understanding barriers to breastfeeding and timing of food diversification. In here, we will review the current understanding and evidence of allergy-associated human microbiota patterns, their role in the development of allergic diseases, and how we could harness these associations to our benefit against allergies.

Allergens and Adjuvants in Allergen Immunotherapy for Immune Activation, Tolerance, and Resilience

Allergen immunotherapy (AIT) is the only setting in which a vaccine is applied in patients allergic exactly to the active principle in the vaccine. Therefore, AIT products need to be not only effective but also safe. In Europe, for subcutaneous AIT, this has been achieved by the allergoid strategy in which IgE epitopes are destroyed or masked. In addition, adjuvants physically precipitate the allergen at the injection site to prevent too rapid systemic distribution. The choice of adjuvant critically shapes the efficacy and type of immune response to the injected allergen. In contrast to T_H2-promoting adjuvants, others clearly counteract allergy. Marketed products in Europe are formulated with aluminum hydroxide (alum) (66.7%), microcrystalline tyrosine (16.7%), calcium phosphate (11.1%), or the T_H1 adjuvant monophosphoryl lipid A (5.6%). In contrast to the European practice, in the United States mostly nonadjuvanted extracts and no allergoids are used for subcutaneous AIT, highlighting not only a regulatory but maybe a "historic preference." Sublingual AIT in the form of drops or tablets is currently applied worldwide without adjuvants, usually with higher safety but lower patient adherence than subcutaneous AIT. This article will discuss how AIT and adjuvants modulate the immune response in the treated patient toward immune activation, modulation, or-with new developments in the pipeline-immune resilience.

Strategic Outlook toward 2030: Japan's research for allergy and immunology - Secondary publication

Strategic Outlook toward 2030: Japan's Research for Allergy and Immunology (Strategy 2030) is the national research strategy based on Japan's Basic Law on Measures Against Allergic Diseases, a first of its kind worldwide. This strategy was established by a multi-disciplinary committee consisting of administrators of the Ministry of Health, Labour and Welfare of Japan, young and senior experts from various research societies and associations, and representatives of patient and public groups. Whereas the issues of transition, integration, and international collaboration have yet to be solved in this research realm in Japan, identification of unmet needs, digitization of information and transparent procedures, and strategic planning for complex problems (a process dubbed MIERUKA by the Toyota Way) are crucial to share and tackle the same vision and goals. The committee developed three specific actions focusing on preemptive treatment, interdisciplinarity and internationality, and life stage. The real success of Strategy 2030 is made by the spontaneous contributions of doctors, dentists, veterinarians, and other medical professionals; basic and clinical research scientists, research supporters, and pharmaceutical/medical device companies; manufacturers of food, healthcare, and home appliances; and patients, their families, and the public. The hope is to establish a stable society in which people can live long, healthy lives, as free as possible from allergic and immunological diseases, at each individual life stage. This article is based on a Japanese review first reported in Arerugi, introduces the developmental process and details of Strategy 2030.

Role of the Microbiome in Allergic Disease Development

PURPOSE OF REVIEW

Evidence suggests that the microbiome of the skin, gastrointestinal tract, and airway contribute to health and disease. As we learn more about the role that the microbiota plays in allergic disease development, we can develop therapeutics to alter this pathway.

RECENT FINDINGS

Epidemiologic studies reveal that an association exists between environmental exposures, which alter the microbiota, and developing atopic dermatitis, food allergy, and/or asthma. In fact, samples from the skin, gastrointestinal tract, and respiratory tract reveal distinct microbiotas compared with healthy controls, with microbial changes (dysbiosis) often preceding the development of allergic disease. Mechanistic studies have confirmed that microbes can either promote skin, gut, and airway health by strengthening barrier integrity, or they can alter skin integrity and damage gut and airway epithelium. In this review, we will discuss recent studies that reveal the link between the microbiota and immune development, and we will discuss ways to influence these changes.

Recent developments and advances in atopic dermatitis and food allergy

This review highlights recent advances in atopic dermatitis (AD) and food allergy (FA), particularly on molecular mechanisms and disease endotypes, recent developments in global strategies for the management of patients, pipeline for future treatments, primary and secondary prevention and psychosocial aspects. During the recent years, there has been major advances in personalized/precision medicine linked to better understanding of disease pathophysiology and precision treatment options of AD. A greater understanding of the molecular and cellular mechanisms of AD through substantial progress in epidemiology, genetics, skin immunology and psychological aspects resulted in advancements in the precision management of AD. However, the implementation of precision medicine in the management of AD still requires the validation of reliable biomarkers, which will provide more tailored management, starting from prevention strategies towards targeted therapies for more severe diseases. Cutaneous exposure to food via defective barriers is an important route of sensitization to food allergens. Studies on the role of the skin barrier genes demonstrated their association with the development of IgE-mediated FA, and suggest novel prevention and treatment strategies for type 2 diseases in general because of their link to barrier defects not only in AD and FA, but also in asthma, chronic rhinosinusitis, allergic rhinitis and inflammatory bowel disease. The development of more accurate diagnostic tools, biomarkers for early prediction, and innovative solutions require a better understanding of molecular mechanisms and the pathophysiology of FA. Based on these developments, this review provides an overview of novel developments and advances in AD and FA, which are reported particularly during the last two years.

Contributions of innate lymphocytes to allergic responses

PURPOSE OF REVIEW

Allergic diseases represent a growing global health concern, especially among pediatric populations. Current strategies for the treatment of allergies and asthma focus on limiting the severity of the symptoms; however, additional research investigating the mechanisms promoting inflammation in the context of allergic reactions may lead to the development of more effective therapeutic strategies.

RECENT FINDINGS

Novel studies have highlighted the contributions of innate lymphocytes to the induction of inflammatory responses to allergens. Remarkably, neuron-derived signals, hormones, and even vitamins have been suggested to modulate the activity of innate lymphocytes, opening new windows of opportunity for the treatment of allergic inflammation.

SUMMARY

These studies highlight the complex interactions of the nervous, endocrine, and immune system that promote pathology in the context of allergic inflammation. Further studies are required to understand these interactions in order to aid in the development of novel and much-needed therapies to treat allergic conditions.

Clinical efficacy of sublingual immunotherapy is associated with restoration of steady-state serum lipocalin 2 after SLIT: a pilot study

Background

So far, only a few biomarkers in allergen immunotherapy exist that are associated with a clinical benefit. We thus investigated in a pilot study whether innate molecules such as the molecule lipocalin-2 (LCN2), with implications in immune tolerance demonstrated in other fields, may discriminate A) between allergic and non-allergic individuals, and B) between patients clinically responding or non-responding to sublingual allergen immunotherapy (SLIT) with house dust mite (HDM) extract. Moreover, we assessed haematological changes potentially correlating with allergic symptoms.

Methods

LCN2-concentrations were assessed in sera of healthy and allergic subjects (n = 126) as well as of house dust mite (HDM) allergics before and during HDM- sublingual immunotherapy (SLIT) in a randomized, double-blind, placebo-controlled trial for 24 weeks. Sera pre-SLIT (week 0), post-SLIT (week 24) and 9 months after SLIT were assessed for LCN2 levels and correlated with total nasal symptom scores (TNSS) obtained during chamber challenge at week 24 in patients receiving HDM- (n = 31) or placebo-SLIT (n = 10).

Results

Allergic individuals had significantly (p < 0.0001) lower LCN2-levels than healthy controls. HDM-allergic patients who received HDM-SLIT showed a significant increase in LCN2 9 months after termination of HDM-SLIT (p < 0.001), whereas in subjects receiving placebo no increase in LCN2 was observed. Among blood parameters a lower absolute rise in the lymphocyte population (p < 0.05) negatively correlated with symptom improvement (Pearson r 0.3395), and a lower relative increase in the neutrophils were associated with improvement in TNSS (p < 0.05). LCN2 levels 9 months after immunotherapy showed a low positive correlation with the relative improvement of symptoms (Pearson r 0.3293). LCN2-levels 9 months off-SLIT were significantly higher in patients whose symptoms improved during chamber challenge than in those whose symptoms aggravated (p < 0.01).

Conclusion

Serum LCN2 concentrations 9 months off-SLIT correlated with clinical reactivity in allergic patients. An increase in the LCN2 levels 9 months after HDM-SLIT was associated with a clinical benefit. Serum LCN2 may thus contribute to assess clinical reactivity in allergic patients.

Trial registration

Part of the data were generated from clinicaltrials.gov Identifier NCT01644617.

Microcrystalline Tyrosine and Aluminum as Adjuvants in Allergen-Specific Immunotherapy Protect from IgE-Mediated Reactivity in Mouse Models and Act Independently of Inflammasome and TLR Signaling

Allergen immunotherapy (AIT) is the only modality that can modify immune responses to allergen exposure, but therapeutic coverage is low. One strategy to improve AIT safety and efficacy is the use of new or improved adjuvants. This study investigates immune responses produced by microcrystalline tyrosine (MCT)–based vaccines as compared with conventional aluminum hydroxide (alum). Wild-type, immune-signaling–deficient, and TCR-transgenic mice were treated with different Ags (e.g., OVA and cat dander Fel d 1), plus MCT or alum as depot adjuvants. Specific Ab responses in serum were measured by ELISA, whereas cytokine secretion was measured both in culture supernatants by ELISA or by flow cytometry of spleen cells. Upon initiation of AIT in allergic mice, body temperature and further clinical signs were used as indicators for anaphylaxis. Overall, MCT and alum induced comparable B and T cell responses, which were independent of TLR signaling. Alum induced stronger IgE and IL-4 secretion than MCT. MCT and alum induced caspase-dependent IL-1β secretion in human monocytes in vitro, but inflammasome activation had no functional effect on inflammatory and Ab responses measured in vivo. In sensitized mice, AIT with MCT-adjuvanted allergens caused fewer anaphylactic reactions compared with alum-adjuvanted allergens. As depot adjuvants, MCT and alum are comparably effective in strength and mechanism of Ag-specific IgG induction and induction of T cell responses. The biocompatible and biodegradable MCT seems therefore a suitable alternative adjuvant to alum-based vaccines and AIT.

Comparing immediate-type food allergy in humans and companion animals-revealing unmet needs

Adverse food reactions occur in human as well as veterinary patients. Systematic comparison may lead to improved recommendations for prevention and treatment in both. In this position paper, we summarize the current knowledge on immediate-type food allergy vs other food adverse reactions in companion animals, and compare this to the human situation. While the prevalence of food allergy in humans has been well studied for some allergens, this remains to be investigated for animal patients, where owner-reported as well as veterinarian-diagnosed food adverse reactions are on the increase. The characteristics of the disease in humans vs dogs, cats, and horses are most often caused by similar, but sometimes species-dependent different pathophysiological mechanisms, prompting the specific clinical symptoms, diagnoses, and treatments. Furthermore, little is known about the allergen molecules causative for type I food allergy in animals, which, like in human patients, could represent predictive biomarkers for risk evaluation. The definite diagnosis of food allergy relies-as in humans-on elimination diet and provocation tests. Besides allergen avoidance in daily practice, novel treatment options and tolerization strategies are underway. Taken together, numerous knowledge gaps were identified in veterinary food allergy, which need to be filled by systematic comparative studies.