Highlights of Novel Vaccination Strategies in Allergen Immunotherapy

Sialic acid-modified der p 2 allergen exerts immunomodulatory effects on human PBMCs

Background

House dust mite extract-based allergen immunotherapy (AIT) to treat house dust mite allergy is substantially effective but still presents some safety and efficacy concerns that warrant improvement. Several major allergen-based approaches to increase safety and efficacy of AIT have been proposed. One of them is the use of the group 2 allergen, Der p 2.

Objective

We sought to investigate the immunomodulatory effects of sialic acid-modified major allergen recombinant Der p 2 (sia-rDer p 2) on PBMCs from healthy volunteers.

Methods

We activated PBMCs with anti-CD3/CD28 antibodies and incubated them at 37°C for 6 days in the presence or absence of either native rDer p 2 or α2-3 sialic acid-modified rDer p 2 (sia-rDer p 2). We assessed the changes in CD4+ T-cell activation and proliferation by flow cytometry and changes in T-lymphocyte cytokine production in cell culture supernatant by ELISA.

Results

We observed that PBMCs treated with sia-rDer p 2 presented with a markedly decreased expression of CD69 and an increased abundance of LAG-3+ lymphocytes compared with cells treated with rDer p 2. Moreover, PBMCs treated with sia-rDer p 2 showed a reduced production of IL-4, IL-13, and IL-5 and displayed a higher IL-10/IL-5 ratio compared with rDer p 2-treated PBMCs.

Conclusions

We demonstrate that sia-rDer p 2 might be a safer option than native rDer p 2 for Der p 2-specific AIT. This is most relevant in the early phase of AIT that is often characterized by heightened TH2 responses, because sia-rDer p 2 does not enhance the production of TH2 cytokines.

A, Hussain SM, Viswanad V, Nasr MH, Sahu RK, Khan J. Modulation of immune response by nanoparticle-based immunotherapy against food allergens

The increasing prevalence of food allergies worldwide and the subsequent life-threatening anaphylactic reactions often have sparse treatment options, providing only symptomatic relief. Great strides have been made in research and in clinics in recent years to offer novel therapies for the treatment of allergic disorders. However, current allergen immunotherapy has its own shortcomings in terms of long-term efficacy and safety, due to the local side effects and the possibility of anaphylaxis. Allergen-specific immunotherapy is an established therapy in treating allergic asthma, allergic rhinitis, and allergic conjunctivitis. It acts through the downregulation of T cell, and IgE-mediated reactions, as well as desensitization, a process of food tolerance without any allergic events. This would result in a protective reaction that lasts for approximately 3 years, even after the withdrawal of therapy. Furthermore, allergen-specific immunotherapy also exploits several routes such as oral, sublingual, and epicutaneous immunotherapy. As the safety and efficacy of allergen immunotherapy are still under research, the exploration of newer routes such as intra-lymphatic immunotherapy would address unfulfilled needs. In addition, the existence of nanoparticles can be exploited immensely in allergen immunotherapy, which would lead to safer and efficacious therapy. This manuscript highlights a novel drug delivery method for allergen-specific immunotherapy that involves the administration of specific allergens to the patients in gradual increasing doses, to induce desensitization and tolerance, as well as emphasizing different routes of administration, mechanism, and the application of nanoparticles in allergen-specific immunotherapy.

Pathogenesis of allergic diseases and implications for therapeutic interventions

Allergic diseases such as allergic rhinitis (AR), allergic asthma (AAS), atopic dermatitis (AD), food allergy (FA), and eczema are systemic diseases caused by an impaired immune system. Accompanied by high recurrence rates, the steadily rising incidence rates of these diseases are attracting increasing attention. The pathogenesis of allergic diseases is complex and involves many factors, including maternal-fetal environment, living environment, genetics, epigenetics, and the body's immune status. The pathogenesis of allergic diseases exhibits a marked heterogeneity, with phenotype and endotype defining visible features and associated molecular mechanisms, respectively. With the rapid development of immunology, molecular biology, and biotechnology, many new biological drugs have been designed for the treatment of allergic diseases, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-5, and anti-thymic stromal lymphopoietin (TSLP)/IL-4, to control symptoms. For doctors and scientists, it is becoming more and more important to understand the influencing factors, pathogenesis, and treatment progress of allergic diseases. This review aimed to assess the epidemiology, pathogenesis, and therapeutic interventions of allergic diseases, including AR, AAS, AD, and FA. We hope to help doctors and scientists understand allergic diseases systematically.

Molecular Aspects of Allergen-Specific Immunotherapy in Patients with Seasonal Allergic Rhinitis

A systematic review and narrative synthesis of publications was undertaken to analyze the role of component-resolved diagnosis technology in identifying polysensitization for the provision of allergen-specific immunotherapy to patients with seasonal allergic rhinitis. A search of publications was carried out in electronic databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search helped to identify 568 publications, 12 of which were included in this review. Overall, 3302 patients were enrolled. The major finding was that component-resolved diagnostics change the choice of relevant allergens for allergen-specific immunotherapy in at least 50% of cases. Sensitization to allergen components differs with age, type of disease, and overall disease duration. Patients who had both bronchial asthma and allergic rhinitis were sensitized to a larger number of allergens than patients who had bronchial asthma alone.

One hundred and ten years of Allergen Immunotherapy: A journey from empiric observation to evidence

One hundred and ten years after Noon's first clinical report of the subcutaneous application of allergen extracts, allergen immunotherapy (AIT) has evolved as the most important pillar of the treatment of allergic patients. It is the only disease-modifying treatment option available and the evidence for its clinical efficacy and safety is broad and undisputed. Throughout recent decades, more insights into the underlying mechanisms, in particular the modulation of innate and adaptive immune responses, have been described. AIT is acknowledged by worldwide regulatory authorities, and following the regulatory guidelines for product development, AIT products are subject to a rigorous evaluation before obtaining market authorization. Knowledge and practice are anchored in international guidelines, such as the recently published series of the European Academy of Allergy and Clinical Immunology (EAACI). Innovative approaches continue to be further developed with the focus on clinical improvement by, for example, the usage of adjuvants, peptides, recombinants, modification of allergens, new routes of administration, and the concomitant use of biologicals. In addition, real-life data provide complementary and valuable information on the effectiveness and tolerability of this treatment option in the clinical routine. New mobile health technologies and big-data approaches will improve daily treatment convenience, adherence, and efficacy of AIT. However, the current coronavirus disease 2019 (COVID-19) pandemic has also had some implications for the feasibility and practicability of AIT. Taken together, AIT as the only disease-modifying therapy in allergic diseases has been broadly investigated over the past 110 years laying the path for innovations and further improvement.

Nanoparticles in allergen immunotherapy

PURPOSE OF REVIEW

Allergen immunotherapy is the only recognized causal treatment for allergic disease that modulates the immune system toward a tolerogenic or desensitized state. Allergens or their derivative preparations are formulated with adjuvants of different origin and having diverse immunological functions, such as prolonged tissue release and specific immunomodulatory properties. In the last 2 decades, thanks to developments in the field of nanotechnology, more biosafe nanoscale materials have become available for use as pharmaceutical adjuvants in medical research.

RECENT FINDINGS

Nanomaterials possess unique and versatile properties which can be employed to develop drug carriers with safer profiles, better stability in physiological conditions and immunomodulatory properties. Nanoparticles can have an adjuvant effect per se or also when they are packed in structures whose physical-chemical properties can be handled in a way that also influences its release dynamics. In particular, it has been suggested that nanoparticle preparations can be put in complexes or loaded with allergens or allergenic extracts, opening the way to innovative paradigms.

SUMMARY

In this review, we analyze allergen/nanoparticle properties in terms of cytotoxicity, stability and immunogenic reaction in in-vitro and animal systems.

Peptide Allergen Immunotherapy: A New Perspective in Olive-Pollen Allergy

Allergic diseases are highly prevalent disorders, mainly in industrialized countries where they constitute a high global health problem. Allergy is defined as an immune response “shifted toward a type 2 inflammation” induced by the interaction between the antigen (allergen) and IgE antibodies bound to mast cells and basophils that induce the release of inflammatory mediators that cause the clinical symptoms. Currently, allergen-specific immunotherapy (AIT) is the only treatment able to change the course of these diseases, modifying the type 2 inflammatory response by an allergenic tolerance, where the implication of T regulatory (Treg) cells is considered essential. The pollen of the olive tree is one of the most prevalent causes of respiratory allergic diseases in Mediterranean countries, inducing mainly nasal and conjunctival symptoms, although, in areas with a high antigenic load, olive-tree pollen may cause asthma exacerbation. Classically, olive-pollen allergy treatment has been based on specific immunotherapy using whole-olive pollen extracts. Despite extracts standardization, the effectiveness of this strategy varies widely, therefore there is a need for more effective AIT approaches. One of the most attractive is the use of synthetic peptides representing the B- or T-cell epitopes of the main allergens. This review summarizes experimental evidence of several T-cell epitopes derived from the Ole e 1 sequence to modulate the response to olive pollen in vitro, associated with several possible mechanisms that these peptides could be inducing, showing their usefulness as a safe preventive tool for these complex diseases.

Allergoid-mannan conjugates reprogram monocytes into tolerogenic dendritic cells via epigenetic and metabolic rewiring

BACKGROUND

Allergoid-mannan conjugates are novel vaccines for allergen-specific immunotherapy being currently assayed in phase 2 clinical trials. Allergoid-mannan conjugates target dendritic cells (DCs) and generate functional forkhead box P3 (FOXP3)-positive Treg cells, but their capacity to reprogram monocyte differentiation remains unknown.

OBJECTIVE

We studied whether allergoid-mannan conjugates could reprogram monocyte differentiation into tolerogenic DCs and the underlying molecular mechanisms.

METHODS

Monocytes from nonatopic and allergic subjects were differentiated into DCs under conventional protocols in the absence or presence of allergoid-mannan conjugates. ELISA, real-time quantitative PCR, coculture, flow cytometry, and suppression assay were performed. Metabolic and epigenetic techniques were also used.

RESULTS

Monocyte differentiation from nonatopic and allergic subjects into DCs in the presence of allergoid-mannan conjugates yields stable tolerogenic DCs. Lipopolysaccharide-stimulated mannan-tolDCs show a significantly lower cytokine production, lower TNF-α/IL-10 ratio, and higher expression of the tolerogenic molecules PDL1, IDO, SOCS1, SOCS3, and IL10; and they induce higher numbers of functional FOXP3⁺ Treg cells than conventional DC counterparts. Mannan-tolDCs shift glucose metabolism from Warburg effect and lactate production to mitochondrial oxidative phosphorylation. They also display epigenetic reprogramming involving specific histone marks within tolerogenic loci and lower expression levels of histone deacetylase genes. Mannan-tolDCs significantly increase the expression of the anti-inflammatory miRNA-146a/b and decrease proinflammatory miRNA-155.

CONCLUSIONS

Allergoid-mannan conjugates reprogram monocyte differentiation into stable tolerogenic DCs via epigenetic and metabolic reprogramming. Our findings shed light on the novel mechanisms by which allergoid-mannan conjugates might contribute to allergen tolerance induction during allergen-specific immunotherapy.

One Hundred Ten Years of Allergen Immunotherapy: A Broad Look Into the Future

Allergen immunotherapy (AIT) is the only disease-modifying treatment option for patients with type 1-mediated allergic diseases such as allergic rhinitis/rhinoconjunctivitis with/without allergic asthma. Although many innovations have been developed since the first clinical report of Noon et al in 1911, the improvement of clinical efficacy and tolerability of this treatment is still an important unmet need. Hence, much progress has been made in the characterization of the cell types, cytokines, and intracellular signaling events involved in the development, maintenance, and regulation of allergic reactions, and also in the understanding of the mechanisms of tolerance induction in AIT. This comprehensive review aims to summarize the current innovative approaches in AIT, but also gives an outlook on promising candidates of the future. On the basis of an extensive literature review, integrating a clinical point of view, this article focuses on recent and future innovations regarding biologicals, allergen-derived peptides, recombinant allergens, "Toll"-like receptor agonists and other adjuvants, and novel application routes being developed for future AIT.

B regulatory cells in allergy

B cells have classically been recognized for their unique and indispensable role in the production of antibodies. Their potential as immunoregulatory cells with anti-inflammatory functions has received increasing attention during the last two decades. Herein, we highlight pioneering studies in the field of regulatory B cell (Breg) research. We will review the literature on Bregs with a particular focus on their role in the regulation of allergic inflammation.

Allergic rhinitis

Allergic rhinitis (AR) is caused by immunoglobulin E (IgE)-mediated reactions to inhaled allergens and is one of the most common chronic conditions globally. AR often co-occurs with asthma and conjunctivitis and is a global health problem causing major burden and disability worldwide. Risk factors include inhalant and occupational allergens, as well as genetic factors. AR impairs quality of life, affects social life, school and work, and is associated with substantial economic costs. The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative classified AR into intermittent or persistent and mild or moderate/severe. The diagnosis is based on the clinical history and, if needed in patients with uncontrolled rhinitis despite medications or with long-lasting symptoms, on skin tests or the presence of serum-specific IgE antibodies to allergens. The most frequently used pharmacological treatments include oral, intranasal or ocular H₁-antihistamines, intranasal corticosteroids or a fixed combination of intranasal H₁-antihistamines and corticosteroids. Allergen immunotherapy prescribed by a specialist using high-quality extracts in stratified patients is effective in patients with persistent symptoms. Real-world data obtained by mobile technology offer new insights into AR phenotypes and management. The outlook for AR includes a better understanding of novel multimorbid phenotypes, health technology assessment and patient-centred shared decision-making.

Immunological Outcomes of Allergen-Specific Immunotherapy in Food Allergy

IgE-mediated food allergies are caused by adverse immunologic responses to food proteins. Allergic reactions may present locally in different tissues such as skin, gastrointestinal and respiratory tract and may result is systemic life-threatening reactions. During the last decades, the prevalence of food allergies has significantly increased throughout the world, and considerable efforts have been made to develop curative therapies. Food allergen immunotherapy is a promising therapeutic approach for food allergies that is based on the administration of increasing doses of culprit food extracts, or purified, and sometime modified food allergens. Different routes of administration for food allergen immunotherapy including oral, sublingual, epicutaneous and subcutaneous regimens are being evaluated. Although a wealth of data from clinical food allergen immunotherapy trials has been obtained, a lack of consistency in assessed clinical and immunological outcome measures presents a major hurdle for evaluating these new treatments. Coordinated efforts are needed to establish standardized outcome measures to be applied in food allergy immunotherapy studies, allowing for better harmonization of data and setting the standards for the future research. Several immunological parameters have been measured in food allergen immunotherapy, including allergen-specific immunoglobulin levels, basophil activation, cytokines, and other soluble biomarkers, T cell and B cell responses and skin prick tests. In this review we discuss different immunological parameters and assess their applicability as potential outcome measures for food allergen immunotherapy that may be included in such a standardized set of outcome measures.

Advances in allergen immunotherapy for asthma

PURPOSE OF REVIEW

Allergen immunotherapy (AIT) is a well-known disease-modifying intervention for allergic diseases. Its benefit in allergic asthma, ranging from prevention to facilitating asthma control, is yet to be clarified.

RECENT FINDINGS

In 2017, following several well-designed randomised controlled trials (RCTs) with house-dust mites (HDM) sublingual (SLIT) tablets in asthma, global initiative for asthma (GINA) guidelines highlighted the need to treat the allergic component of asthma. In 2019, the European Academy of Allergy and Clinical Immunology published the first comprehensive guidelines for HDM AIT in allergic asthma, formulating separate recommendations for subcutaneous, SLIT drops, and SLIT tablets. Significant steps were undertaken in understanding the mechanisms of allergic asthma, facilitating the stratified approach for selecting responders and in translating the immune-modulation effect in achieving long-term control of the chronic inflammation in asthma.

SUMMARY

Currently existing guidelines recommend AIT as a therapeutic option in controlled or partially controlled HDM allergic asthma. Limited data are available for pollen, molds and pets, as well as for the severe allergic asthma population. The challenge for the future research will be to clarify the subendotypes of allergic asthma responding to AIT, the mechanisms facilitating its' preventive and disease-modifying effect, the optimal duration of the treatment, and route of administration.

Asthma immunotherapy and treatment approaches with mesenchymal stem cells

Asthma is a chronic inflammatory disease of the airways where exaggerated T helper 2 immune responses and inflammatory mediators play a role. Current asthma treatment options can effectively suppress symptoms and control the inflammatory process; however, cannot modulate the dysregulated immune response. Allergen-specific immunotherapy is one of the effective treatments capable of disease modification. Injecting allergens under the skin in allergen-specific immunotherapy can reduce asthma and improve the sensitivity of the lungs, however, has a risk of severe reactions. Mesenchymal stem cells have immunoregulatory activity with their soluble mediators and contact dependent manner. In this review, we focus on the current treatment strategies with mesenchymal stem cells in asthma as a new therapeutic tool and compare those with immunotherapy.