Notch signaling contributes to the establishment of sustained unresponsiveness to food allergens by oral immunotherapy

Allergen immunotherapy combined with Notch pathway inhibitors improves HDM-induced allergic airway inflammation and inhibits ILC2 activation

Introduction

Group 2 innate lymphoid cells (ILC2s) play a crucial role in house dust mite (HDM)-induced allergic inflammation, and allergen immunotherapy (AIT) holds promise for treating the disease by reducing the frequency of ILC2s. Despite significant progress in AIT for allergic diseases, there remains a need to improve the control of allergic symptoms.

Methods

We investigated the synergistic effect of the Notch signaling pathway and subcutaneous immunotherapy (SCIT) in treating allergic airway inflammation in mice and their impact on the ratio of ILC2s in lung tissues. This was achieved by establishing the HDM-induced airway allergic disorders (HAAD) model and SCIT model. Additionally, we conducted in vitro investigations into the effect of the Notch signaling pathway on the secretory function of activated ILC2s using fluorescence-activated cell sorting. Furthermore, we explored the coactivation of the Notch signaling pathway with SCIT in vitro by sorting ILC2s from the lung tissues of mice after SCIT modeling.

Results

Previously, our group demonstrated that Notch signaling pathway inhibitors can reduce allergic airway inflammation in mice. Notch signaling induces lineage plasticity of mature ILC2s. In this study, we showed that AIT alleviates allergic airway inflammation and suppresses the frequency of ILC2s induced by HDM. Interestingly, AIT combined with a γ-secretase inhibitor (GSI), an inhibitor of the Notch signaling pathway, significantly inhibited the frequency of ILC2s, reduced airway inflammation, and suppressed Th2-type responses in a mouse model. Furthermore, lung ILC2s from HDM-challenged mice with or without AIT were treated with GSI in vitro, and we found that GSI dramatically reduced the secretion of type 2 inflammatory factors in ILC2s.

Discussion

These findings suggest that Notch signaling pathway inhibitors can be used as adjuvant therapy for AIT and may hold potential treatment value in the cooperative control of allergic airway inflammation during early AIT.

Notch1 signalling controls the differentiation and function of myeloid-derived suppressor cells in systemic lupus erythematosus

Emerging studies have reported the expansion of myeloid-derived suppressor cells (MDSCs) in some autoimmune disorders, such as systemic lupus erythematosus (SLE), but the detailed molecular mechanisms of the aberrant expansion in SLE are still unclear. In the present study, we confirmed that the increased MDSCs positively correlated with disease activity in SLE patients. The suppressive capacity of MDSCs from patients with high activity was lower than that of MDSCs from patients with low activity. Moreover, the potential precursors for MDSCs, common myeloid progenitors (CMPs) and granulocyte-monocyte progenitors (GMPs), were markedly increased in the bone marrow (BM) aspirates of SLE patients. As an important regulator of cell fate decisions, aberrant activation of Notch signalling was reported to participate in the pathogenesis of SLE. We found that the expression of Notch1 and its downstream target gene hairy and enhancer of split 1 (Hes-1) increased markedly in GMPs from SLE patients. Moreover, the Notch1 signalling inhibitor DAPT profoundly relieved disease progression and decreased the proportion of MDSCs in pristane-induced lupus mice. The frequency of GMPs was also decreased significantly in lupus mice after DAPT treatment. Furthermore, the inhibition of Notch1 signalling could limit the differentiation of MDSCs in vitro. The therapeutic effect of DAPT was also verified in Toll-like receptor 7 (TLR7) agonist-induced lupus mice. Taken together, our results demonstrated that Notch1 signalling played a crucial role in MDSC differentiation in SLE. These findings will provide a promising therapy for the treatment of SLE.

Immunotherapy: State-of-the-art review of therapies and theratypes

Through its disease-modifying potential, immunotherapy is the keystone to curing allergic diseases. Allergen immunotherapy, applied for more than a century, is currently supported by novel modalities such as mAb-based therapies or small molecules targeting the key nodes of the allergic inflammation network. In this review, a summary of the most significant advances in immunotherapy is presented, addressing not only novel approaches to stratifying patients but also major controlled clinical trials and real-world evidence that strengthen the role of immunotherapy in the treatment of allergies.

Biomarkers in oral immunotherapy

Food allergy (FA) is a global health problem that affects a large population, and thus effective treatment is highly desirable. Oral immunotherapy (OIT) has been showing reasonable efficacy and favorable safety in most FA subjects. Dependable biomarkers are needed for treatment assessment and outcome prediction during OIT. Several immunological indicators have been used as biomarkers in OIT, such as skin prick tests, basophil and mast cell reactivity, T cell and B cell responses, allergen-specific antibody levels, and cytokines. Other novel indicators also could be potential biomarkers. In this review, we discuss and assess the application of various immunological indicators as biomarkers for OIT.

Mucosal Mast Cells as Key Effector Cells in Food Allergies

Mucosal mast cells (MMCs) localized in the intestinal mucosa play a key role in the development of IgE-mediated food allergies. Recent advances have revealed that MMCs are a distinctly different population from connective tissue mast cells localized in skin and other connective tissues. MMCs are inducible and transient cells that arise from bone marrow-derived mast cell progenitors, and their numbers increase rapidly during mucosal allergic inflammation. However, the mechanism of the dramatic expansion of MMCs and their cell functions are not well understood. Here, we review recent findings on the mechanisms of MMC differentiation and expansion, and we discuss the potential for the inducers of differentiation and expansion to serve as targets for food allergy therapy. In addition, we also discuss the mechanism by which oral immunotherapy, a promising treatment for food allergy patients, induces unresponsiveness to food allergens and the roles of MMCs in this process. Research focusing on MMCs should provide useful information for understanding the underlying mechanisms of food allergies in order to further advance the treatment of food allergies.

The year in food allergy

Research into food allergy continues to rapidly evolve, accompanying and driving real changes in the clinical approach to these diseases. The past year has seen the rollout of the first treatment approved for active management of food allergy, more data on alternative methods of treatment, the continued evolution of strategies for prevention of food allergy, a renewed interest in phenotyping food allergy subtypes, and, importantly, key new insights into the pathophysiology of food allergy. We expect that in the coming years, the therapies that are in preclinical or early clinical evaluation now will make their way to the clinic, finally allowing the possibility of safe and effective treatments for food allergy.

Oral Immunotherapy in Patients with IgE Mediated Reactions to Egg White: A Clinical Trial Study

BACKGROUND

Oral immunotherapy (OIT) is under consideration as a promising treatment for desensitization of egg-allergic patients. The objective of this study was to assess the effectiveness of egg-white OIT in patients with IgE-mediated allergy to egg white and to compare the clinical and laboratory findings before and after OIT.

METHODS

This clinical trial was performed from February to August 2018 in Rasool e Akram Hospital, Tehran, Iran. Patients' selection criteria included a history of allergic symptoms, skin prick test (SPT) reactivity to egg white, and the inability to pass the Oral Food Challenge (OFC). Egg-white OIT was done for eight patients in the OIT group for 6 months while egg-white-free products were administrated for controls. The SPT reactivity, specific IgE, and IgG4 for egg white and ovomucoid were evaluated before and after OIT.

RESULTS

Hundred percent of the subjects in OIT group were desensitized and tolerated 40 cc raw egg white following 6-month maintenance whereas none of the controls was able to pass the OFC. The findings obtained from the evaluations indicated a significant decrease in the wheal size and specific IgE to egg white after OIT (P = .001). Furthermore, a significant decrease of IgE/IgG4 ratio to egg white was found in OIT group (P = .01).

CONCLUSION

This OIT protocol was successful as all OIT patients were able to continue 6-month OIT process and the reaction threshold to egg white increased in the OIT group. Therefore, it could be regarded as an effective and safe protocol to treat egg-allergic patients.

The Role of Regulatory T Cells in Epicutaneous Immunotherapy for Food Allergy

In recent decades, a rapid increase in the prevalence of food allergies has led to extensive research on novel treatment strategies and their mechanisms. Mouse models have provided preliminary insights into the mechanism of epicutaneous immunotherapy (EPIT)-induced immune tolerance. In EPIT, antigen applied on the skin surface can be captured, processed, and presented in the lymph nodes (LNs) by Antigen-presenting cells (APCs). In the LNs, induction of regulatory T cells (Treg cells) requires both direct contact during antigen presentation and indirect mechanisms such as cytokines. Foxp3⁺CD62L⁺ Treg cells can exhibit the characteristics of hypomethylation of Foxp3 TSDR and Foxp3^-LAP⁺ Treg cells, which increase the expression of surface tissue-specific homing molecules to exert further sustained systemic immune tolerance. Studies have shown that EPIT is a potential treatment for food allergies and can effectively induce immune tolerance, but its mechanism needs further exploration. Here, we review Treg cells' role in immune tolerance induced by EPIT and provide a theoretical basis for future research directions, such as the mechanism of EPIT and the development of more effective EPIT treatments.

The use of biologics in food allergy

BACKGROUND

Food allergy continues to pose problems due to its increased frequency and its increasingly high severity. In this context, alongside the traditional avoidance strategies of allergenic foods and desensitization through the cautious progression of exposure to foods in the context of oral immunotherapy (OIT), alternative strategies have made their way in the last decades. We review the possibilities of intervention in food allergy with the use of biological drugs capable of interfering with the synthesis of IgE, with their mechanisms of action, or with complex biological mechanisms that lead to the establishment of a food allergy.

METHODS

Repeated Entrez PubMed searches using the template algorithm "Food allergy" and "biologics" or "Omalizumab" or "Dupilumab" or "milk desensitization" or "oral tolerance induction" or "oral immunotherapy" or "Etokimab" or "Tezepelumab" or "Quilizumab" or "Ligelizumab" or "Tralokinumab" or "Nemolizumab" or "Mepolizumab" or "Reslizumab" or "Benralizumab". The authors' clinical experience in paediatric allergy units of University hospitals was also drawn upon.

RESULTS

The landscape in this context has changed dramatically over the past 10 years. We have acquired knowledge mainly on the effect of different types of anti-IgE treatments in poliallergic patients with food allergy, and in patients treated with OIT. However, other mediators are being targeted by specific biologic treatments. Among them, the alarmins Il-33 and TSLP, IL-4 and IL-13, eosinophil-related molecules as IL-6, IL-8, IL-10, IL-12, and mostly IL-5, and integrins involved in the pathogenesis of eosinophilic gastrointestinal diseases (EGIDs), as SIGLEC-8.

CONCLUSIONS

The ever-better knowledge of the mechanisms of food allergy allowing these developments will improve not only the perspective of patients with the most serious immediate food allergies such as anaphylaxis, but also those of patients with related diseases such as atopic dermatitis, eosinophilic esophagitis, and EGIDs. Biologics are also intended to complement OIT strategies that have developed over the years.

Mechanisms of oral immunotherapy

Food allergy presents a significant global health concern with up to 10% of the population affected in developed nations and a steadily increasing prevalence. In many cases, particularly with peanut, tree nut and shellfish, food allergy is a lifelong and potentially life-threatening diagnosis. While no 'cure' for IgE-mediated food allergy exists, oral immunotherapy (OIT) is a promising treatment modality with the peanut OIT drug Palforzia (Aimmune Therapeutics) the only treatment for food allergy that is currently approved by the United States Food and Drug Administration. OIT primarily induces a state of desensitization with only a minority of subjects achieving sustained unresponsiveness, a state of limited clinical remission that appears to be immunologically distinct from natural tolerance. Early humoural changes during OIT include an initial increase in allergen-specific IgE, which eventually decreases to below baseline levels as OIT progresses, and a gradual increase in allergen-specific IgA and IgG4 that continues throughout the course of OIT. Basophil hyporesponsiveness and decreased skin prick test wheal size are observed within the first year of OIT, and persistence after completion of therapy has been associated with sustained unresponsiveness. In the T-cell compartment, there is an initial expansion followed by a decline in the number and activity of T helper 2 (TH 2) cells, the latter of which may be dependent on an expansion of IL-10-producing cells, including regulatory T-cells. Our understanding of the immunomodulatory effects of OIT continues to evolve, with new technologies such as single-cell transcriptional profiling and antibody epitope analysis allowing for more detailed study of T-cell and B-cell responses to OIT. In this review, we present evidence to illustrate what is currently known about the immunologic changes induced by OIT, explore potential mechanisms and emphasize knowledge gaps where future research is needed.