Scientific foundations of allergen-specific immunotherapy for allergic disease

On the role of allergen-specific IgG subclasses for blocking human basophil activation

Successful treatment of IgE mediated allergies by allergen-specific immunotherapy (AIT) usually correlates with the induction of allergen-specific IgG4. However, it is not clear whether IgG4 prevents the allergic reaction more efficiently than other IgG subclasses. Here we aimed to compare allergen-specific monoclonal IgG1 and IgG4 antibodies in their capacity to inhibit type I allergic reactions by engaging FcγRIIb. We found that IgG1, which is the dominant subclass induced by viruses, binds with a similar affinity to the FcγRIIb as IgG4 and is comparable at blocking human basophil activation from allergic patients; both by neutralizing the allergen as well as engaging the inhibitory receptor FcγRIIb. Hence, the IgG subclass plays a limited role for the protective efficacy of AIT even if IgG4 is considered the best correlate of protection, most likely simply because it is the dominant subclass induced by classical AITs.

A randomized trial of subcutaneous allergy immunotherapy in inner-city children with asthma less than 4 years of age

BACKGROUND

Allergic sensitization to environmental allergens in the first years of life is a strong predictor of asthma morbidity in children. Allergy immunotherapy can improve asthma and allergy outcomes, but its efficacy in inner-city, atopic children of less than 4 years of age with recurrent wheezing has not yet been established.

OBJECTIVE

To determine whether subcutaneous allergy immunotherapy improves asthma in a population of US inner-city children when started at less than 4 years of age.

METHODS

In a randomized controlled, open-label phase I-II single-center trial in the Bronx, New York, 58 children with recurrent wheezing or physician-diagnosed asthma were randomized to receive asthma standard of care treatment with or without a 3-year course of multiple allergen subcutaneous immunotherapy.

RESULTS

A total of 23 children in the control group and 27 children in the immunotherapy group began the study. A total of 20 of 27 children commencing immunotherapy completed at least 2 years of immunotherapy. There was no difference in asthma medication and symptom scores between the treatment or control groups over time. Similarly, naso-ocular symptoms and allergy medication use were similar in both groups over time. Nevertheless, asthma-related quality of life improved in the immunotherapy group compared with the control group (P = .03).

CONCLUSION

With the exception of asthma-related quality of life, allergy immunotherapy was ineffective in improving asthma outcomes in this population of inner-city children of less than 4 years of age. These findings suggest that the effects of allergy immunotherapy depend on population-specific factors and highlight the importance of precise predictors of immunotherapy efficacy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01028560.

Safety of semi-depot house dust mite allergen extract in children and adolescents with allergic rhinitis and asthma

Aim: Multicenter study to investigate the safety of mite extract product Novo-Helisen Depot, Strengths 1 to 3 (NHD3), as subcutaneous immunotherapy (SCIT), in Chinese children and adolescents with allergic rhinitis (AR) and allergic asthma (AA). Patients & methods: We evaluated SCIT-related adverse events (AEs) during NHD3 14-week initial therapy in children (5-11 years) and adolescents (12-17 years) with perennial symptomatic AR and AA. Results: Among 3600 injections in 250 patients, 361/3600 (10.0%) injections caused SCIT-related AEs in 96/250 (38.4%) patients, 321/3600 injections (8.9%) caused local reactions in 89/250 (35.6%) and 40/3600 injections (1.1%) caused systemic reactions in 23/250 (9.2%). Conclusion: Initial SCIT treatment using NHD3 was safe and well tolerated in Chinese children and adolescents with AR and AA.

Effect of Dermatophagoides pteronyssinus Immunotherapy on Upper and Lower Airway Eosinophilic Inflammatory Response to Nasal Allergen Challenge

Purpose

It remains unknown whether allergen-specific immunotherapy (AIT) could attenuate airway inflammatory response triggered by allergen exposure.

Methods

We performed Dermatophagoides pteronyssinus (Der-p) nasal provocation tests (NPTs) in allergic rhinitis (AR) and/or asthma patients without AIT (non-AIT), or at 16, 52, 104, or 156 weeks after Der-p AIT. Rhinitis and asthma visual analog scale (VAS; VAS of nasal symptoms [VAS-NS], VAS of asthma symptoms), the rhinoconjunctivitis quality of life questionnaire (RQLQ), nasal lavage, sputum induction, fractional exhaled nitric oxide (FeNO), nasal airway resistance, pulmonary function, and airway hyperresponsiveness were performed before and after NPT.

Results

Non-AIT subjects demonstrated significantly higher VAS-NS before and after NPT compared to AIT subjects (P < 0.05). NPT response was positive in 14 (100%) non-AIT, 7 (70%) 16 weeks-AIT, 6 (60%) 52 weeks-AIT, 6 (60%) 104 weeks-AIT, and 2 (20%) 156 weeks-AIT subjects. The NPT grade significantly correlated with AIT duration and baseline RQLQ score (r = −0.561, P < 0.001 and r = 0.525, P < 0.001, respectively). Sputum and nasal lavage eosinophil count, and FeNO in non-AIT subjects were significantly increased 6 hours after NPT (P < 0.05). AIT subjects did not change their sputum or nasal lavage eosinophil count before and after NPT. Subjects with 156 weeks-AIT demonstrated significantly lower levels of sputum and nasal lavage eosinophil count before and after NPT when compared with non-AIT patients (P < 0.05). Sputum eosinophil counts positively correlated with nasal lavage eosinophil counts at baseline and 6 hours after NPT (r = 0.719, P = 0.006 and r = 0.823, P < 0.001, respectively) in non-AIT patients.

Conclusion

Our results show that AIT can attenuate both upper and lower airway immune response to nasal allergen exposure in patients with AR and/or asthma.

House dust mite subcutaneous immunotherapy in Chinese patients with allergic asthma and rhinitis

The efficacy of allergen immunotherapy (AIT) has been reported with different allergens including house dust mites (HDM). HDM are the most prevalent allergens in patients with asthma and/or rhinitis in China. In addition to improving symptoms, reducing medication need, and improving quality of life, AIT can change the course of allergic disease and induce allergen-specific immune tolerance. To date, the use of AIT is becoming more acceptable in China, and there are many studies about the current clinical practice immunotherapy. In this paper we discuss the main aspects of AIT undertaken in China; including symptom and medication scores, pulmonary function and airway hyperresponsiveness, specific allergen sensitivity, safety evaluation, and mechanisms underlying AIT. This review will provide some important information on AIT treatment strategies to doctors, healthcare professionals and organizations involved in the AIT in China. According to the studies in China, successful AIT may induce antibody responses and cellular reactions in relation to the significant improvement in clinical symptoms, reducing the need for medications and maintenance of stable pulmonary functions.

Der p 1-specific regulatory T-cell response during house dust mite allergen immunotherapy

BACKGROUND

Allergen-specific immunotherapy (AIT) is the only available treatment for allergic diseases that can induce specific immune tolerance to allergens. The key mechanisms involved in this process include changes in allergen-specific regulatory T (Treg) cells.

METHODS

We studied 25 allergic rhinitis patients undergoing subcutaneous house dust mite-specific immunotherapy. Peripheral blood mononuclear cells were studied before and after 10, 30 weeks, and 3 years of AIT. Der p 1-specific T regulatory cell responses were investigated by characterization of Der p 1-MHC class II tetramer-positive cells and correlated with nasal symptom score.

RESULTS

Twelve of 25 AIT patients matched with their MHC class II expression to the Der p 1 peptide-MHC class II tetramers. A significant increase in the numbers of Der p 1-specific FOXP3⁺ Helios⁺ CD25⁺ CD127^- Treg cells after 30 weeks was observed, which slightly decreased after 3 years of AIT. In contrast, Der p 1-specific immunoglobulin-like transcript 3 (ILT3)⁺ CD25⁺ Treg cells decreased substantially from baseline after 3 years of AIT. ILT3⁺ Treg cells displayed compromised suppressive function and low FOXP3 expression. In addition, Der p 1-specific IL-10 and IL-22 responses have increased after 30 weeks, but only IL-10⁺ Der p 1-specific Treg cells remained present at high frequency after 3 years of AIT. Increased number of FOXP3⁺ Helios⁺ and IL-10⁺ and decreased ILT3⁺ Treg cell responses correlated with improved allergic symptoms.

CONCLUSION

The results indicate that AIT involves upregulation of the activated allergen-specific Treg cells and downregulation of dysfunctional allergen-specific Treg cell subset. Correction of dysregulated Treg cells responses during AIT is associated with improved clinical response.

Therapeutic Effects of Short Cyclic and Combined Epitope Peptides in a Long-Term Model of Graves' Disease and Orbitopathy

BACKGROUND

Cyclic peptides derived from some cylindrical loops of the leucine-rich repeat domain (LRD) of the thyrotropin receptor (TSHR) have been shown to treat disease manifestations in a mouse model of Graves' disease during a long-term protocol of four-weekly immunizations with adenovirus coding for the TSHR A-subunit (Ad-TSHR289).

METHODS

In a follow-up study, two additional cyclic peptides were tested, which were shortened in order to obtain additional information on the minimally involved epitopes and to enable easier production conditions. In addition, a linear peptide was tested, which mimics parts of three loops of the native TSHR LRD structure, and is potentially able to block the discontinuous epitopes of anti-TSHR antibodies.

RESULTS

The novel peptides markedly reduced thyroid size, serum thyroxine levels, retro-orbital fibrosis, and tachycardia in Ad-TSHR289-immunized mice. In immunologically naïve mice, administration of the peptides did not induce any immune response.

CONCLUSIONS

In summary, novel cyclic peptides mitigate many clinical findings in a mouse model of established Graves' disease and orbitopathy, and may therefore provide an additional therapeutic option compared to existing drugs or interventions.

The role of regulatory B cells in allergen immunotherapy

PURPOSE OF REVIEW

Allergen immunotherapy (AIT) is currently the only curative treatment available for allergic diseases, and has been used in clinical practice for over a century. Induction and maintenance of immune tolerance to nonhazardous environmental and self-antigens is essential to maintain homeostasis and prevent chronic inflammation. Regulatory B (BREG) cells are immunoregulatory cells that protect against chronic inflammatory responses primarily through production of anti-inflammatory cytokines such as IL-10, transforming growth factor-β, and IL-35. The importance of BREG cells has been extensively demonstrated in the context of autoimmune diseases. Data showing their role in the regulation of allergic responses are slowly accumulating. This review summarizes recent findings relevant to the topic of BREG cells and their potential role in AIT.

RECENT FINDINGS

BREG cells support AIT in models of allergic airway inflammation and intestinal inflammation through induction of regulatory T (TREG) cells. In humans BREG frequency increases during venom immunotherapy while the phenotype of allergen-specific B cells changes. Mechanisms of BREG-mediated tolerance to allergens include IL-10-mediated suppression of effector T cell, including TH2 responses, induction of TREG cells, IL-10-mediated inhibition of Dendritic cell maturation, modulation of T follicular helper responses, and production of anti-inflammatory IgG4 antibodies.

SUMMARY

Current evidence supports a potential role for BREG cells in induction and maintenance of allergen tolerance during AIT. A better understanding of the role of B cells and BREG cells in AIT could open potential new windows for developing targeted therapies specifically focused on promoting BREG responses during AIT.

Accelerated subcutaneous immunotherapy in pediatric population - Systematic review

BACKGROUND

Accelerated subcutaneous immunotherapy (SCIT) schedules represent an alternative to conventional SCIT, providing immunotherapy benefits in a shorter period of time. The objectives of this systematic review were to assess clinical and immunological efficacy as well as safety of accelerated SCIT build-up schedules for the treatment of respiratory allergy in pediatric patients.

METHODS

Studies were located by searching PubMed, using "immunotherapy" and "desensitization" as keywords. The selection of studies, published from January 1st, 2006, to December 31th, 2015, was performed in two stages: screening of titles and abstracts, and assessment of the full papers identified as relevant, considering the inclusion criteria. Data were extracted in a standardized way and synthesized qualitatively to assess efficacy and safety of accelerated schedules in respiratory allergy.

RESULTS

Eleven trials were included: two evaluated rush SCIT and nine assessed cluster SCIT. This review demonstrated that rush and cluster schedules are clinically and immunological efficacious, with faster effect than conventional schedules. No relevant difference with respect to clinical outcomes was noticed between subgroups (pediatric, adult and mixed populations). Regarding safety, most local adverse reactions were mild and there were neither life-threatening systemic reactions nor fatal events. No relevant differences in the incidence and severity of either local or systemic reactions between the accelerated schedule group and control group were registered.

CONCLUSIONS

Accelerated SCIT build-up schedules are effective in the treatment of respiratory allergy in pediatric patients, representing a safe alternative to the conventional schedules with the advantage of achieving clinical effectiveness sooner.

Accurate quantification of 5 German cockroach (GCr) allergens in complex extracts using multiple reaction monitoring mass spectrometry (MRM MS)

BACKGROUND

German cockroach (GCr) allergen extracts are complex and heterogeneous products, and methods to better assess their potency and composition are needed for adequate studies of their safety and efficacy.

OBJECTIVE AND METHODS

The objective of this study was to develop an assay based on liquid chromatography and multiple reaction monitoring mass spectrometry (LC-MRM MS) for rapid, accurate, and reproducible quantification of 5 allergens (Bla g 1, Bla g 2, Bla g 3, Bla g 4, and Bla g 5) in crude GCr allergen extracts.

RESULTS

We first established a comprehensive peptide library of allergens from various commercial extracts as well as recombinant allergens. Peptide mapping was performed using high-resolution MS, and the peptide library was then used to identify prototypic and quantotypic peptides to proceed with MRM method development. Assay development included a systematic optimization of digestion conditions (buffer, digestion time, and trypsin concentration), chromatographic separation, and MS parameters. Robustness and suitability were assessed following ICH (Q2 [R1]) guidelines. The method is precise (RSD < 10%), linear over a wide range (r > 0.99, 0.01-1384 fmol/μL), and sensitive (LLOD and LLOQ <1 fmol/μL). Having established the parameters for LC-MRM MS, we quantified allergens from various commercial GCr extracts and showed considerable variability that may impact clinical efficacy.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data demonstrate that the LC-MRM MS method is valuable for absolute quantification of allergens in GCr extracts and likely has broader applicability to other complex allergen extracts. Definitive quantification provides a new standard for labelling of allergen extracts, which will inform patient care, enable personalized therapy, and enhance the efficacy of immunotherapy for environmental and food allergies.

Cyclic Peptides for Effective Treatment in a Long-Term Model of Graves Disease and Orbitopathy in Female Mice

A model for human Graves disease in mice was used to compare several treatment approaches. The mice received regular adenovirus (Ad) thyroid-stimulating hormone receptor (TSHR) A subunit immunizations (injections every 4 weeks). The generation of anti-TSHR antibodies, enlarged thyroid sizes (goiter), elevated serum thyroxine levels, retro-orbital fibrosis, and cardiac involvement (tachycardia and hypertrophy) were consistently observed over 9 months. Treatment of established disease in these mice using cyclic peptides that mimic one of the cylindrical loops of the TSHR leucine-rich repeat domain improved or cured all investigated parameters after six consecutive monthly injections. The first significant beneficial effects were observed 3 to 4 months after starting these therapies. In immunologically naïve mice, administration of any of the cyclic peptides did not induce any immune response. In contrast, monthly injections of the full antigenic TSHR A domain as fusion protein with immunoglobulin G crystallizable fragment induced clinical signs of allergy in Ad-TSHR-immunized mice and anti-TSHR antibodies in naïve control mice. In conclusion, cyclic peptides resolved many clinical findings in a mouse model of established Graves disease and orbitopathy. In contrast to blocking TSHR by allosteric modulation, the approach does not incur a direct receptor antagonism, which might offer a favorable side effect profile.

Immunotherapy for Cat Allergies: A Potential Strategy to Scratch Back

Cat allergies are a common and costly problem in the United States. Various drug and nondrug therapies exist to alleviate and control symptoms once allergic disease has developed. However, these therapies are often ineffective or do not address the underlying condition itself. Immunotherapy is an option for patients when symptoms are not adequately controlled by medications and/or avoidance measures, when adverse effects of medications are unacceptable, or when the patient wants to reduce their long-term use of medication. The purpose of this article is to describe the efficacy and safety of immunotherapy when used to prevent or treat cat allergies.

Vitamin D3 inhibits micro RNA-17-92 to promote specific immunotherapy in allergic rhinitis

It is recognized that T helper 2 (Th2) polarization plays a critical role in a large number of immune disorders. Yet, the remedies for reconciling the established Th2 polarization are still limited currently. Published data indicate that micro RNA-17-92 cluster is associated with the skewed immune response; 25 vitamin D3 (VD3) can regulate multiple bioactivities in the body. This study tests a hypothesis that VD3 facilitates the effect of specific immunotherapy (SIT) on Th2 response. We observed that treatment with either SIT or VD3 alleviated AR symptoms as well as reduced serum levels of specific IgE and T helper (Th) 2 cytokines, suppressed miR-19a (one of the members of the miR-17-92 cluster) and increased IL-10 in peripheral B cells, which was further improved in those AR patients treated with both SIT and VD3. The expression of miR-19a and IL-10 was significantly negatively correlated with each other in peripheral B cells of AR patients. Metabolites of VD3 formed a complex with retinoid acid receptor to repress the expression of miR-19a in B cells. We conclude that administration with VD3 promotes the effect of SIT on suppression of AR via repressing the expression of miR-19a in peripheral B cells.

Review of Mouse Models of Graves' Disease and Orbitopathy-Novel Treatment by Induction of Tolerance

Various approaches have been used to model human Graves' disease in mice, including transfected fibroblasts, and plasmid or adenoviral immunisations with the extracellular A subunit of the human thyrotropin receptor (TSHR). Some of these models were only observed for a short time period or were self-limiting. A long-term model for human Graves' disease was established in mice using continuing immunisations (4-weekly injections) with recombinant adenovirus expressing TSHR. Generation of TSHR binding cAMP-stimulatory antibodies, thyroid enlargement and alterations, elevated serum thyroxin levels, tachycardia and cardiac hypertrophy were maintained for at least 9 months in all Ad-TSHR-immunised mice. Here, we show that these mice suffer from orbitopathy, which was detected by serial orbital sectioning and histomorphometry. Attempts to treat established Graves' disease in preclinical mouse model studies have included small molecule allosteric antagonists and specific antagonist antibodies which were isolated from hypothyroid patients. In addition, novel peptides have been conceived which mimic the cylindrical loops of the TSHR leucine-rich repeat domain, in order to re-establish tolerance toward the antigen. Here, we show preliminary results that one set of these peptides improves or even cures all signs and symptoms of Graves' disease in mice after six consecutive monthly injections. First beneficial effects were observed 3-4 months after starting these therapies. In immunologically naïve mice, administration of the peptides did not induce any immune response.

Subcutaneous and Sublingual Immunotherapy in a Mouse Model of Allergic Asthma

Allergic asthma, caused by inhaled allergens such as house dust mite or grass pollen, is characterized by reversible airway obstruction, associated with an eosinophilic inflammation of the airways, as well as airway hyper responsiveness and remodeling. The inhaled allergens trigger a type-2 inflammatory response with involvement of innate lymphoid cells (ILC2) and Th2 cells, resulting in high production of immunoglobulin E (IgE) antibodies. Consequently, renewed allergen exposure results in a classic allergic response with a distinct early and late phase, both resulting in bronchoconstriction and shortness of breath. Allergen specific immunotherapy (AIT) is the only treatment that is capable of modifying the immunological process underlying allergic responses including allergic asthma and both subcutaneous AIT (SCIT) as well as sublingual AIT (SLIT) have proven clinical efficacy in long term suppression of the allergic response. Although these treatments are very successful for rhinitis, application of AIT in asthma is hampered by variable efficacy, long duration of treatment, and the risk of severe side-effects. A more profound understanding of the mechanisms by which AIT achieves tolerance to allergens in sensitized individuals is needed to improve its efficacy. Mouse models have been very valuable as a preclinical model to characterize the mechanisms of desensitization in AIT and to evaluate novel approaches for improved efficacy. Here, we present a rapid and reproducible mouse model for allergen-specific immunotherapy. In this model, mice are sensitized with two injections of allergen absorbed to aluminum hydroxide to induce allergic sensitization, followed by subcutaneous injections (SCIT) or sublingual administrations (SLIT) of the allergen as immunotherapy treatment. Finally, mice are challenged by three intranasal allergen administrations. We will describe the protocols as well as the most important read-out parameters including measurement of invasive lung function measurements, serum immunoglobulin levels, isolation of broncho-alveolar lavage fluid (BALF), and preparation of cytospins. Moreover, we describe how to restimulate lung single cell suspensions, perform flow cytometry measurements to identify populations of relevant immune cells, and perform ELISAs and Luminex assays to measure the cytokine concentrations in BALF and lung tissue.

Primary vaccine failure to routine vaccines: Why and what to do?

There are 2 major factors responsible for vaccine failures, the first is vaccine-related such as failures in vaccine attenuation, vaccination regimes or administration. The other is host-related, of which host genetics, immune status, age, health or nutritional status can be associated with primary or secondary vaccine failures. The first describes the inability to respond to primary vaccination, the latter is characterized by a loss of protection after initial effectiveness. Our studies concentrate on the evaluation of immunological characteristics responsible for primary vaccine failures in different (risk) populations for which the underlying mechanisms are currently unknown. Here we summarise current knowledge and findings from our studies.

About 2–10% of healthy individuals fail to mount antibody levels to routine vaccines. Comparing the immune responses to different vaccines in non-responder and high-responder vaccinees revealed that hypo-responsiveness is antigen/vaccine-specific at the humoral but not at the cellular level. We found that T-regulatory as well as B-regulatory cells and the production of IL-10 are involved in non/hypo-responsiveness. Non-responsiveness increases with age and in particular vaccination to a novel vaccine in persons > 65 years is associated with a high low/non-responder rate, indicating that vaccine schedules and doses (at least for primary vaccination) should be adapted according to age.

In light of the growing number of allergic but also obese people, our current studies concentrate on these risk groups to reveal whether different vaccination approaches are necessary for optimal protection compared to healthy individuals. These studies are in line with the significant paradigm shift taking place in many fields of medical research and care, and will extend the concept of personalised medicine into the field of vaccinology.

Molecular cloning, expression, IgE binding activities and in silico epitope prediction of Per a 9 allergens of the American cockroach

Per a 9 is a major allergen of the American cockroach (CR), which has been recognized as an important cause of imunoglobulin E-mediated type I hypersensitivity worldwide. However, it is not neasy to obtain a substantial quantity of this allergen for use in functional studies. In the present study, the Per a 9 gene was cloned and expressed in Escherichia coli (E. coli) systems. It was found that 13/16 (81.3%) of the sera from patients with allergies caused by the American CR reacted to Per a 9, as assessed by enzyme-linked immunosorbent assay, confirming that Per a 9 is a major allergen of CR. The induction of the expression of CD63 and CCR3 in passively sensitized basophils (from sera of patients with allergies caused by the American CR) by approximately 4.2-fold indicated that recombinant Per a 9 was functionally active. Three immunoinformatics tools, including the DNAStar Protean system, Bioinformatics Predicted Antigenic Peptides (BPAP) system and the BepiPred 1.0 server were used to predict the potential B cell epitopes, while Net-MHCIIpan-2.0 and NetMHCII-2.2 were used to predict the T cell epitopes of Per a 9. As a result, we predicted 11 peptides (23-28, 39-46, 58-64, 91-118, 131-136, 145-154, 159-165, 176-183, 290-299, 309-320 and 338-344) as potential B cell linear epitopes. In T cell prediction, the Per a 9 allergen was predicted to have 5 potential T cell epitope sequences, 119-127, 194-202, 210-218, 239-250 and 279-290. The findings of our study may prove to be useful in the development of peptide-based vaccines to combat CR-induced allergies.

Clostridium butyricum in combination with specific immunotherapy converts antigen-specific B cells to regulatory B cells in asthmatic patients

The effect of antigen specific immunotherapy (SIT) on asthma is supposed to be improved. Published data indicate that administration of probiotics alleviates allergic diseases. B cells play important roles in the pathogenesis of allergic diseases. This study aims to modulate antigen specific B cell property by the administration of Clostridium butyrate (CB) in combination with SIT. The results showed that after a 3-month treatment, the total asthma clinical score and serum specific IgE were improved in the patients treated with SIT, which was further improved in those treated with both SIT and CB, but not in those treated with CB alone. Treatment with SIT and CB increased p300 and STAT3 activation, up regulated the IL-10 gene transcription and increased the frequency of peripheral antigen specific B cells. In conclusion, administration with SIT in combination with CB converts Der p 1 specific B cells to regulatory B cells in asthma patients allergic to Der p 1. The data suggest a potential therapeutic remedy in the treatment of allergic diseases.

Carboplatin Hypersensitivity Reactions in Pediatric Low Grade Glioma Are Protocol Specific and Desensitization Shows Poor Efficacy

BACKGROUND

The use of carboplatin for the treatment of pediatric low grade gliomas (PLGG) is often limited by the development of carboplatin hypersensitivity. Reported rates of carboplatin hypersensitivity reactions vary between 6% and 32% in these patients. Here we report the frequency of carboplatin hypersensitivity reactions depending on the treatment regimen used, and outcomes of carboplatin desensitization.

METHODS

The records of all patients in a single institution who were treated with carboplatin for PLGG were accessed and all patients receiving more than one dose of carboplatin are reported.

RESULTS

Thirty four patients with PLGG were treated with carboplatin according to one of the two different regimens. Carboplatin hypersensitivity was documented in 47% of patients, but the frequency differed by treatment protocol. Those patients treated with 4-weekly single agent carboplatin had carboplatin allergy in 8% of cases whereas 68% of those treated with combined carboplatin and vincristine (every three weeks, according to the SIOP 2004 low grade glioma protocol) had carboplatin reactions (OR 23.6, P < 0.01). Desensitization was only successful in two out of 10 patients in whom it was attempted.

CONCLUSIONS

Hypersensitivity reactions to carboplatin are more common in this cohort than previously reported and rates are protocol-dependent. Desensitization showed limited effectiveness in this cohort.

Specific allergen immunotherapy attenuates allergic airway inflammation in a rat model of Alstonia scholaris pollen induced airway allergy

Pollen grains are well established to be an important cause of respiratory allergy. Current pharmacologic therapies for allergic asthma do not cure the disease. Allergen specific immunotherapy is the only treatment method which re-directs the immune system away from allergic response leading to a long lasting effect. The mechanism by which immunotherapy achieves this goal is an area of active research world-wide. The present experimental study was designed to develop an experimental model of allergic lung inflammation based on a relevant human allergen, Alstonia scholaris pollen, and to establish the immunological and cellular features of specific allergen immunotherapy using this same pollen extract. Our results revealed that Alstonia scholaris pollen sensitization and challenge causes eosinophilic airway inflammation with mucin hypersecretion. This is associated with increased total IgE, increased expression of FcɛRI on lung mast cells and increased levels of IL-4, IL-5 & IL-13 as confirmed by ELISA, in-situ immunofluorescence and FACS assay. Allergen specific immunotherapy reduced airway inflammation and also decreased total IgE level, FcɛRI expression, IL-4, IL-5 & IL-13 levels. It was further noted that the reduction of these levels was more by intra-nasal route than by intra-peritoneal route. Thus we present a novel animal model of Alstonia scholaris pollen allergic disease and specific allergen immunotherapy which will pave the way towards the development of better treatment modalities.

From IgE to clinical trials of allergic rhinitis

The current scientific research is continuously aiming at identifying new therapeutic targets with the purpose of modifying the immune response to allergens. The evolution in immunological methods has led to the identification of immunoglobulin E (IgE) as both a diagnostic biomarker and potential therapeutic target in allergic diseases, such as allergic rhinitis. Allergen immunotherapy has been used for more than 100 years to treat allergic diseases and it is today considered the only disease-modifying treatment capable of inducing a long-lasting immunological and clinical tolerance toward the causal allergen. During the past 20 years, major advances have been made in understanding the molecular and cellular mechanisms of allergen tolerance in humans. Moreover, there has been considerable progress in allergen extract modifications and additions to standard extracts. The recognition that IgE plays a pivotal role in basic regulatory mechanisms of allergic inflammation has recently stimulated research into the therapeutic potential of directly targeting this antibody. Omalizumab, the most advanced humanized anti-IgE monoclonal antibody, is currently approved for the treatment of uncontrolled allergic asthma and chronic spontaneous urticaria. Interesting results also arise from studies in which omalizumab was administered in patients with allergic rhinitis. The aim of this review is to provide an update on current findings on immunological and clinical effects of allergen immunotherapy and anti-IgE therapy, which have been shown to have synergistic modes of action for the treatment of allergic rhinitis.

Mechanisms of allergen-specific immunotherapy and immune tolerance to allergens

Substantial progress in understanding mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumors, organ transplantation and chronic infections has led to a variety of targeted therapeutic approaches. Allergen-specific immunotherapy (AIT) has been used for 100 years as a desensitizing therapy for allergic diseases and represents the potentially curative and specific way of treatment. The mechanisms by which allergen-AIT has its mechanisms of action include the very early desensitization effects, modulation of T- and B-cell responses and related antibody isotypes as well as inhibition of migration of eosinophils, basophils and mast cells to tissues and release of their mediators. Regulatory T cells (Treg) have been identified as key regulators of immunological processes in peripheral tolerance to allergens. Skewing of allergen-specific effector T cells to a regulatory phenotype appears as a key event in the development of healthy immune response to allergens and successful outcome in AIT. Naturally occurring FoxP3⁺ CD4⁺CD25⁺ Treg cells and inducible type 1 Treg (Tr1) cells contribute to the control of allergen-specific immune responses in several major ways, which can be summarized as suppression of dendritic cells that support the generation of effector T cells; suppression of effector Th1, Th2 and Th17 cells; suppression of allergen-specific IgE, and induction of IgG4; suppression of mast cells, basophils and eosinophils and suppression of effector T cell migration to tissues. New strategies for immune intervention will likely include targeting of the molecular mechanisms of allergen tolerance and reciprocal regulation of effector and regulatory T cell subsets.

Asthma

Asthma is the most common inflammatory disease of the lungs. The prevalence of asthma is increasing in many parts of the world that have adopted aspects of the Western lifestyle, and the disease poses a substantial global health and economic burden. Asthma involves both the large-conducting and the small-conducting airways, and is characterized by a combination of inflammation and structural remodelling that might begin in utero. Disease progression occurs in the context of a developmental background in which the postnatal acquisition of asthma is strongly linked with allergic sensitization. Most asthma cases follow a variable course, involving viral-induced wheezing and allergen sensitization, that is associated with various underlying mechanisms (or endotypes) that can differ between individuals. Each set of endotypes, in turn, produces specific asthma characteristics that evolve across the lifecourse of the patient. Strong genetic and environmental drivers of asthma interconnect through novel epigenetic mechanisms that operate prenatally and throughout childhood. Asthma can spontaneously remit or begin de novo in adulthood, and the factors that lead to the emergence and regression of asthma, irrespective of age, are poorly understood. Nonetheless, there is mounting evidence that supports a primary role for structural changes in the airways with asthma acquisition, on which altered innate immune mechanisms and microbiota interactions are superimposed. On the basis of the identification of new causative pathways, the subphenotyping of asthma across the lifecourse of patients is paving the way for more-personalized and precise pathway-specific approaches for the prevention and treatment of asthma, creating the real possibility of total prevention and cure for this chronic inflammatory disease.