Current insights in allergen immunotherapy

Viral protein-based nanoparticles (part 2): Pharmaceutical applications

Viral protein nanoparticles (ViP NPs) such as virus-like particles and virosomes are structures halfway between viruses and synthetic nanoparticles. The biological nature of ViP NPs endows them with the biocompatibility, biodegradability, and functional properties that many synthetic nanoparticles lack. At the same time, the absence of a viral genome avoids the safety concerns of viruses. Such characteristics of ViP NPs offer a myriad of opportunities for theirapplication at several points across disease development: from prophylaxis to diagnosis and treatment. ViP NPs present remarkable immunostimulant properties, and thus the vaccination field has benefited the most from these platforms capable of overcoming the limitations of both traditional and subunit vaccines. This was reflected in the marketing authorization of several VLP- and virosome-based vaccines. Besides, ViP NPs inherit the ability of viruses to deliver their cargo to target cells. Because of that, ViP NPs are promising candidates as vectors for drug and gene delivery, and for diagnostic applications. In this review, we analyze the pharmaceutical applications of ViP NPs, describing the products that are commercially available or under clinical evaluation, but also the advances that scientists are making toward the implementation of ViP NPs in other areas of major pharmaceutical interest.

Early life exposure to house dust mite allergen prevents experimental allergic asthma requiring mitochondrial H2O2

Immune tolerance to allergens in early-life decreases the risk for asthma in later life. Here we show establishment of stable airway tolerance to the allergen, house dust mite (HDM), by exposing newborn mice repeatedly to a low dose of the allergen. Lung dendritic cells (DCs) from tolerized mice induced a low Th2 response in vitro mirroring impact of tolerance in vivo. In line with our previous finding of increased mitochondrial H₂O₂ production from lung DCs of mice tolerized to ovalbumin, depletion of mitochondrial H₂O₂ in MCAT mice abrogated HDM-induced airway tolerance (Tol) with elevated Th2 effector response, airway eosinophilia, and increased airway hyperreactivity. WT-Tol mice displayed a decrease in total, cDC1 and cDC2 subsets in the lung as compared to that in naive mice. In contrast, the lungs of MCAT-Tol mice showed 3-fold higher numbers of cDCs including those of the subsets as compared to that in WT mice. Our study demonstrates an important role of mitochondrial H₂O₂ in constraining lung DC numbers towards establishment of early-life airway tolerance to allergens.

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.

30 years of sublingual immunotherapy

Allergen Immunotherapy (AIT) was introduced in clinical practice on an empirical basis more than 100 years ago. Since the first attempts, AIT was administered subcutaneously. Indeed, other routes of administration were proposed and studied, in particular to improve the safety, but only the sublingual route (SLIT) achieved a credibility based on evidence and was then accepted as a viable "alternative" option to the subcutaneous route. SLIT was largely used in clinical trials and clinical practice in this last 30 years. Thus, a large amount of data is available, coming from either controlled trials and postmarketing surveillance studies. It is clear that SLIT is overall effective, but it is also clear that the efficacy is not "class-related," as derived from meta-analyses, but restricted to each specific product. The 30-year lasting use of SLIT allowed to clarify many clinical aspects, such as efficacy, safety, use in asthma, regimens of administration, and optimal doses. In parallel, the mechanisms of action of AIT were elucidated, and new indications were proposed (eg food allergy, atopic dermatitis). In addition, the introduction of molecular-based diagnosis, allowed to better refine the prescription of SLIT, based on specific sensitization profiles. The present article will describe the origin and evolution of SLIT for respiratory allergy, taking into account the clinical context that suggested this form of treatment, the recently developed aspects, the future perspectives and unmet needs, This is not, therefore, a systematic review, rather a narrative historical description of the past history, and a look forward to the future opportunities.

A WAO - ARIA - GA2LEN consensus document on molecular-based allergy diagnosis (PAMD@): Update 2020

Precision allergy molecular diagnostic applications (PAMD@) is increasingly entering routine care. Currently, more than 130 allergenic molecules from more than 50 allergy sources are commercially available for in vitro specific immunoglobulin E (sIgE) testing. Since the last publication of this consensus document, a great deal of new information has become available regarding this topic, with over 100 publications in the last year alone. It thus seems quite reasonable to publish an update. It is imperative that clinicians and immunologists specifically trained in allergology keep abreast of the new and rapidly evolving evidence available for PAMD@.

PAMD@ may initially appear complex to interpret; however, with increasing experience, the information gained provides relevant information for the allergist. This is especially true for food allergy, Hymenoptera allergy, and for the selection of allergen immunotherapy. Nevertheless, all sIgE tests, including PAMD@, should be evaluated within the framework of a patient's clinical history, because allergen sensitization does not necessarily imply clinical relevant allergies.

The safety of carbamylated monomeric allergoids for sublingual immunotherapy. Data from a pharmacovigilance study

Aim: Sublingual immunotherapy (SLIT) is significantly less concerned by systemic reactions than subcutaneous immunotherapy. Allergoids were introduced to reduce systemic reaction to subcutaneous immunotherapy, but may also be used for SLIT. Methods: This pharmacovigilance study evaluated the post-marketing reports collected in a safety database, including the number and the type (serious or not serious) of adverse drug reactions (ADRs) in Italy by SLIT with the carbamylated monomeric allergoid (CMA). Results: More than 15,000,000 CMA tablets were administered, with 25 spontaneous reports of ADRs, only two being serious. Conclusion: The rate of ADRs to CMA we found in this pharmacovigilance survey, corresponding to 0.0004% of all administered doses, is far lower than the rates commonly reported for allergen SLIT products.

House dust mite-specific immunotherapy alters the natural course of atopic march

Allergen immunotherapy (AIT) is an effective treatment for patients with allergic diseases; it has been shown to modify the underlying cause of the disease. The house dust mite (HDM) is a major perennial allergen source and a significant cause of allergic-related diseases such as allergic rhinitis, asthma, and atopic dermatitis. HDM allergen is an important factor in the pathogenesis of allergic diseases. Sensitization to HDM allergen often occurs early in life and appears to play an important role in the progression from allergic rhinitis to asthma in children. The role of HDM AIT results in immunologic tolerance, provides an alternative option for treating HDM allergy through targeting the mechanisms of allergic reaction, and creates a long-term benefit. There are two forms of testing for aeroallergen, either detect by skin testing or by in vitro IgE assays. Both subcutaneous immunotherapy and sublingual immunotherapy are effective in the treatment of allergic diseases. In the future, new forms of allergen extracts can help improve safety and efficacy of AIT. Novel approaches to immunotherapy currently being explored include the use of adjuvants, allergen-derived peptides, modified recombinant allergen vaccines, and gene-specific immunotherapy.

Evolving phenotypes to endotypes: is precision medicine achievable in asthma?

Introduction: The development of biologic molecules led to a drastic change in the therapeutic approach to asthma. With the prospect of acting on different pathophysiological mechanisms of the disease, the idea of precision medicine was developed, in which a single molecule is able to modify a specific triggering mechanism. Thus, it seemed limiting to stop at the distinction of patients phenotypes and the concept of endotypes became more relevant in the therapeutic approach.Areas covered: This review deepened the topic of precision medicine through the transition from phenotyping to endotyping. We performed a review of the literature, preferring articles quoted in Medline and published in journals with an impact factor. Results showed that it is fundamental to take into consideration the role of biomarkers and the related therapies currently available for precision medicine.Expert opinion: The possible overlap of patients in different phenotypes requires a more precise classification, which considers endotypization. With the development of biological drugs able to modify and modulate some pathophysiological mechanisms of the disease, the theoretical concept of endotyping becomes practical, allowing the clinician to choose the specific mechanism to 'attack' in order to control the disease.

Advances in allergen immunotherapy as a treatment of asthma

Introduction: Specific immunotherapy is the only treatment acting on causes and not only on symptoms of respiratory allergy. It was first introduced as subcutaneous immunotherapy (SCIT) with the aim to induce immunological tolerance to the administered allergen(s). In the 1980s, sublingual immunotherapy (SLIT) was developed, mainly to improve the safety, which was a critical issue at that time.Areas covered: This article reviews the available literature, including a large number of randomized controlled trials, meta-analyses, and real-life studies as well, on the outcomes of SCIT and SLIT concerning the treatment critical issues of the two routes, that are efficacy, safety, cost-effectiveness, and compliance to treatment.Expert opinion: SCIT and SLIT are similarly effective in treating patients with respiratory allergy, providing, based on the induction of typical changes in the immunologic response, an early control of symptoms that steadily increases during the treatment and, once reached the recommended duration of 3 years, continues to work after stopping. This outcome is the major factor influencing the economic advantage of SCIT and SLIT over drug treatment.

Strategies to reduce corticosteroid-related adverse events in asthma

PURPOSE OF REVIEW

Severe asthmatics, despite the chronic use of high inhaled corticosteroids (ICS) doses and frequent intake of systemic corticosteroids, remains clinically and/or functionally uncontrolled. These patients are also often affected by rhinitis or chronic rhinosinusitis requiring frequent use of intranasal corticosteroids. Therefore, severe asthmatics are exposed to an overload of corticosteroids that is frequently associated with relevant and costly adverse events. This clinical problem and the strategies to overcome it are here summarized.

RECENT FINDINGS

Different therapeutic options may help in reducing the corticosteroid load in asthmatics, ranging from allergy immunotherapy (nonsuitable for severe uncontrolled patients), immunosuppressant agents like methotrexate or cyclosporine, novel biologic drugs (mainly anti-IgE, anti-IL5 and anti-IL4-receptor-alpha), and aspirin desensitization (for patients with anti-inflammatory drugs exacerbated respiratory disease).

SUMMARY

The evidence of even serious corticosteroid-related adverse events associated with consistent health-care costs, should prompt the entire scientific community and health regulatory authorities to promote actions to increase the use of well tolerated and effective strategies to reduce the corticosteroid need in asthmatics; the most promising option seems to be the add-on use of biologic agents.

What you should not miss from the systematic reviews and meta-analyses on allergen-specific immunotherapy in 2017

PURPOSE OF REVIEW

Allergen immunotherapy (AIT) is a well recognized and extensively studied therapeutic intervention for some allergic diseases. Every year new systematic reviews and meta-analysis provide the most powerful source of evidence to orient decision making on prevention or efficacy of AIT. We here discuss systematic reviews and meta-analyses on AIT (published January 2017 to February 2018).

RECENT FINDINGS

We identified 4 systematic reviews and 10 meta-analyses. Subcutaneous and sublingual AIT (SCIT/SLIT) significantly reduced the development of asthma in children-adolescents with moderate/severe allergic rhinitis, but evidence for a short-term, preventive effect for new allergic sensitizations was nonconclusive. SCIT/SLIT proved to significantly improve symptom and medication scores versus placebo or active comparators in respiratory allergy, with various effect sizes. Oral immunotherapy for IgE-mediated food allergy resulted in substantial benefit in desensitization rates. Data on venom AIT and latex AIT, although limited in quantity and quality, respectively, suggest a large and discrete beneficial effect.

SUMMARY

Although current evidence extracted from meta-analyses and systematic reviews support AIT as an effective, relatively safe, and well tolerated alternative for some allergic diseases, heterogeneity and some methodological inconsistencies represent matters of concern as they may affect the validity and applicability of their results, especially in the context of individual, real-life settings.

Perception and practice of sublingual immunotherapy among practicing allergists in the United States: A follow-up survey

BACKGROUND

Limited information is available regarding the current perception and practice of sublingual immunotherapy (SLIT) use among US and international allergists. In light of 4 recent US Food and Drug Administration (FDA)-approved SLIT options, perceptions and practices may be changing.

OBJECTIVE

To provide updated information about current allergists' practice and perception of SLIT relative to 2007 and 2011.

METHODS

On behalf of the American College of Allergy, Asthma, and Immunology (ACAAI) Immunotherapy and Diagnostics Committee, an electronic survey was sent to all US and international allergists who were members of the ACAAI. Data were compared with previous surveys conducted and published in 2007 and 2011.

RESULTS

Of the 305 respondents, 268 (87.9%) practiced in the United States. A total of 197 of 268 respondents (73.5%) reported experience using SLIT compared with 45 of 766 US allergists (5.9%) in 2007 and 59 of 519 US allergists (11.4%) in 2011 (P < .001). Of the 188 respondents in the United States who used SLIT in their practice, 129 (68.6%) used FDA-approved SLIT tablets only, 44 (23.4%) used both FDA-approved SLIT tablets and SLIT drops using an extract that is FDA approved for subcutaneous immunotherapy, and 15 (8.0%) reported using only SLIT drops. Limitation of only treating one allergen was the primary barrier in using SLIT among 197 of 268 respondents (73.5%).

CONCLUSION

There has been a significant increase in SLIT use in the last 5 years, with 73.5% of respondents reporting experience with it. With 4 FDA-approved SLIT therapies, this likely contributes to its more widespread use. The greatest barrier to SLIT use is the limitation of only treating one allergen.

Virus-Like Particles as Carrier Systems to Enhance Immunomodulation in Allergen Immunotherapy

PURPOSE OF REVIEW

Utilization of virus-like particles (VLPs) is considered to improve allergen-specific immunotherapy (AIT). AIT aims at the efficient uptake of the target allergen by antigen-presenting cells (APCs) subsequently inducing adaptive allergen-specific immune responses to induce tolerance. The purpose of this review is to describe the immune-modulating properties of VLPs per se and to summarize the application of VLPs as antigen carriers, preferably for Th2 cytokines or allergens, with and without simultaneous administration of adjuvants in order to modulate allergic immune responses.

RECENT FINDINGS

Currently, a broad variety of approaches considering the origin of the VLPs, the choice of the adjuvant and antigen, and the coupling of the antigen are under preclinical investigation. The data provide evidence that VLPs used as carrier for antigens/allergens strongly increase antigen immunogenicity, and might be suitable to prevent allergies. However, systematic studies in mice showing the immunological mechanism and data from clinical studies are scarce.

Assessment of Th1/Th2 Bias of STING Agonists Coated on Microneedles for Possible Use in Skin Allergen Immunotherapy

Microneedle-based skin allergen-specific immunotherapy (AIT) can benefit from adjuvants that can stimulate a stronger Th1 response against the allergen. We evaluated two stimulator of interferon genes (STING) agonists, namely, cyclic diguanylate monophosphate (c-di-GMP) and cyclic diadenylate monophosphate (c-di-AMP), as skin adjuvants using coated microneedles (MNs). For comparison, the approved subcutaneous (SC) hypodermic injection containing alum was used. Ovalbumin (Ova) was used as a model allergen. Ova-specific IgG2a antibody in serum, which is a surrogate marker for Th1 type immune response was significantly higher when STING agonists were used with coated MNs as compared to SC injection of Ova+alum in mice. In contrast, IgG1 antibody, a surrogate marker for Th2 type immune response, was at comparable levels in the MN and SC groups. Restimulation of splenocytes with Ova produced higher levels of Th1 cytokines (IFN-γ and IL-2) in the STING agonists MN groups as compared to the SC group. In conclusion, delivery of STING agonists into the skin using coated MNs activated the Th1 pathway better than SC- and MN-based delivery of alum. Thus, STING agonists could fulfill the role of adjuvants for skin AIT and even for infectious disease vaccines, where stimulation of the Th1 pathway is of interest.

Investigation of the interaction of allergens of Glycine max with IgE-antibody for designing of peptidomimetics based anti-allergen

Allergen induced IgE dependent type I hypersensitivity is the main cause of the allergy, which would be a burden on medical setup in coming years. Allergens of Glycine max have been isolated, and their disease relationships are documented. Therefore, it becomes important to investigate the interaction of different allergens of Glycine max with IgE and also screen suitable therapeutics to prevent this interaction. The amino acid sequences of all allergens of Glycine max and their isoallergens have been taken, and 3D structure of allergens (Gly m 3, Gly m 4, Gly m 5, Gly m 6 and Gly m 8) and their isoallergens were generated using Modeller v9.17. The modeled structures were further validated using PSVS, ProSA, RAMPAGE, and PDBsum. HL domain of Fab region of human IgE (PDBID: 2R56) was generated using UCSFchimera. The HL domain was minimized by Schrodinger software using the OPLS_2005 force field. SiteMap identified epitope binding site of the minimized domain. All the predicted epitopes of different allergens were docked to the binding site of HL domain using the Patchdock server. We have also designed a peptidomimetics based inhibitor targeted at interaction interface of Gly m8 and IgE, using in-silico virtual screening, molecular mechanics, and molecular dynamics simulation studies. These studies identified BDE32166344 ((N-(1-{[1-(1-aminocyclopentanecarbonyl)-3-hydroxypyrrolidin-3-yl]methyl}piperidin-4-yl)acetamide) as a peptidomimetics based lead with binding energy of -72.77 kcal/mol. Therefore, the present study investigates the interaction between different Gly m allergens and IgE antibody and identifies peptidomimetics based lead that might be developed as a suitable therapeutics against allergy caused by allergen of Glycine max.