Patterns of IgE sensitization in house dust mite-allergic patients: implications for allergen immunotherapy

Polysensitisation is associated with more severe symptoms: The reality of patients with allergy

BACKGROUND

Studying the sensitisation profiles of patients with allergies allows for a deeper understanding of the disease which may facilitate the selection of the best-personalised allergen immunotherapy. This observational, cross-sectional, multicentre study aimed to demonstrate the heterogeneity of the German population with allergies by analysing specific immunoglobulin E (sIgE) patterns towards aeroallergens and exploring the relationship between sensitisation and clinical symptoms.

METHODS

In total, 500 patients with allergies from different regions of Germany were recruited based on their case histories, clinical allergic symptoms and skin prick test data for aeroallergens. Serum samples were analysed using ImmunoCAP assays to determine sIgE levels for 33 allergenic sources and 43 molecular allergens.

RESULTS

Most patients (81%) were polysensitised. Betula verrucosa pollen was the most common cause of sensitisation (59%), followed by Phleum pratense (58%) and Dermatophagoides pteronyssinus (44%). The highest prevalence rates of molecular allergens were observed for Bet v 1 (84%) from birch pollen, Phl p 1 from grass pollen (82%), Der p 2 (69%) from mites and Fel d 1 (69%) from cat. Polysensitisation was significantly associated with the presence of asthma and the severity of rhinitis symptoms.

CONCLUSIONS

Our findings show a high rate of polysensitisation and emphasise the importance of molecular diagnosis for more precise and comprehensive insights into sensitisation patterns and their association with clinical symptoms. These data may help improve personalised diagnosis and immunotherapy adapted to the needs of individual patients in the region.

Triggered Skin Sensitivity: Understanding Contact Dermatitis

Dermatitis, the incendiary reaction of the skin to various components, can manifest in various types, including atopic dermatitis, contact dermatitis, nummular eczema, seborrhoea, and stasis dermatitis. Atopic dermatitis is the most common skin disease in children and has a growing prevalence in recent years. It is characterized by extreme tingling, eczemous skin injuries, dryness of the skin, and a family history of atopic illnesses. Contact dermatitis (CD) is a common, irritating skin disorder caused by allergens and aggravating elements in the environment. It is the most common cause of work-related dermatitis and plays a substantial role in hand and face dermatitis. A complete restorative history is essential for establishing CD and identifying the allergies that cause it. Fix testing, skin tests for fast contact reactions, serum allergen-specific IgE testing, subjective and quantitative evaluation of allergens inside probable items patients were exposed to, and challenge testing are among the other diagnostic techniques. To avoid a breakdown and the continuation of the skin illness, early and suitable therapy is critical. Allergic dermatitis to contact (ACD) develops during the normal, delayed incendiary reaction and has a perplexing etiology. Accurate identification of the allergen that is causing the reaction allows for adequate individual avoidance. The major treatment alternatives continue to be corticosteroids. Nickel-contact dermatitis is an allergic reaction that affects both children and adults. Adverse contact dermatitis (ACD) is a frequent skin reaction to a common allergen that can affect both children and adults. Less than 10% of all diagnostic procedures in pediatric patients involve checking for ACD symptoms. To answer the clinical question, a thorough history is gathered based on appearance, age group, and dermatitis type. According to pediatricians in the US, metals, perfumes, topical antimicrobials, excessive chemicals, and fabric softeners are the most typical allergens.

Structural analysis of human IgE monoclonal antibody epitopes on dust mite allergen Der p 2

BACKGROUND

Human IgE (hIgE) mAbs against major mite allergen Der p 2 developed using human hybridoma technology were used for IgE epitope mapping and analysis of epitopes associated with the hIgE repertoire.

OBJECTIVE

We sought to elucidate the new hIgE mAb 4C8 epitope on Der p 2 and compare it to the hIgE mAb 2F10 epitope in the context of the allergenic structure of Der p 2.

METHODS

X-ray crystallography was used to determine the epitope of anti-Der p 2 hIgE mAb 4C8. Epitope mutants created by targeted mutagenesis were analyzed by immunoassays and in vivo using a human high-affinity IgE receptor (FcεRIα)-transgenic mouse model of passive systemic anaphylaxis.

RESULTS

The structure of recombinant Der p 2 with hIgE mAb 4C8 Fab was determined at 3.05 Å. The newly identified epitope region does not overlap with the hIgE mAb 2F10 epitope or the region recognized by 3 overlapping hIgE mAbs (1B8, 5D10, and 2G1). Compared with wild-type Der p 2, single or double 4C8 and 2F10 epitope mutants bound less IgE antibodies from allergic patients by as much as 93%. Human FcεRIα-transgenic mice sensitized by hIgE mAbs, which were susceptible to anaphylaxis when challenged with wild-type Der p 2, could no longer cross-link FcεRI to induce anaphylaxis when challenged with the epitope mutants.

CONCLUSIONS

These data establish the structural basis of allergenicity of 2 hIgE mAb nonoverlapping epitopes on Der p 2, which appear to make important contributions to the hIgE repertoire against Der p 2 and provide molecular targets for future design of allergy therapeutics.

Mite allergen sensitization patterns in Turkish children: Age-related changes and molecular correlations

BACKGROUND

Mites are ubiquitous aeroallergens found worldwide. Elucidating individual mite allergen sensitization patterns provides critical insights for managing allergic diseases. This study aimed to investigate molecular allergen (MA) sensitization patterns across different age groups and explore cluster relationships among mite-sensitized children.

METHODS

We analyzed 76 children who exhibited sensitization to at least one of the 17 distinct mite MAs through microarray testing.

RESULTS

Dermatophagoides farinae exhibited a slightly higher prevalence of sensitization compared with Dermatophagoides pteronyssinus. Der p 1/2 and Der f 1/2 demonstrated an almost 40% sensitization rate, while Der p 10/Blo t 10, Der p 20, Der p 23, and Gly d 2/Lep d 2 displayed an approximately 20% sensitization rate. Sensitization levels and ratios increased significantly with age for Der p 23 but showed numerical rises for other MAs, except for Der p 10/Blo t 10. The presence of various types of atopic diseases had only a minimal impact on sensitization profiles. Strong correlations emerged between Der f 2 and Der p 2, Der p 10 and Blo t 10, Der p 21 and Blo t 5, as well as Gly d 2 and Lep d 2. Hierarchical cluster analysis substantiated these relationships. Der p 10 and its homolog Blo t 10-sensitive patients (15/76) were mostly seen as mono sensitization(12/15). Ten patients exhibited monosensitization to Der p 20, suggesting a possible association with scabies infection.

CONCLUSION

In children, mite sensitization diversity and levels increased with age. The presence of significant correlations/cluster relationships among these sensitizations underscores homologies among specific MAs.

Inhibition of IL-17 ameliorates keratinocyte-borne cytokine responses in an in vitro model for house-dust-mite triggered atopic dermatitis

A subgroup of patients suffering from atopic dermatitis (AD) does not respond to biologics therapy targeting the key players of type-2 inflammation, and it is an ongoing discussion whether skin-infiltrating Th17 cells may underlie this phenomenon. This study aimed to investigate the potential of allergen-induced, immune-cell derived IL-17 on the induction of inflammatory processes in keratinocytes. Peripheral blood mononuclear cells derived from respectively sensitized AD patients were stimulated with house dust mite (HDM) extract and cell culture supernatants were applied subsequently in absence or presence of secukinumab to primary human keratinocytes. Hereby we confirm that the immune response of sensitized AD patients to HDM contains aside from type-2 cytokines significant amounts of IL-17. Blocking IL-17 efficiently reduced the stimulation-induced changes in keratinocyte gene expression. IL-17-dependent transcriptional changes included increased expression of the cytokines IL-20 and IL-24 as well as Suppressor of Cytokine Siganling 3 (SOCS3), a negative feedback-regulator of the STAT3/IL-17/IL-24 immune response. We conclude that the immune response to HDM can induce pro-inflammatory cytokines from keratinocytes in AD, which in part is mediated via IL-17. Targeting IL-17 may turn out to be a reasonable alternative therapy in a subgroup of patients with moderate to severe AD and HDM sensitization.

[Allergenic and chemical pollutants of indoor environments and asthma: Characterization, assessment and eviction]

The environment of an asthmatic patient can contain numerous sources of pollutants that degrade the quality of indoor air and have major repercussions on the occurrence and control of asthma. Assessment and improvement of the quality of indoor air should be assigned a major role in pneumology and allergology consultations. Characterization of an asthmatic's environment entails a search for biological pollutants with mite allergens, mildew, and allergens resulting from the proximity of pets. It is important to evaluate the chemical pollution represented by exposure to volatile organic compounds, which are increasingly present in our lodgings. Active or second-hand smoking must in all circumstances be sought out and quantified. Assessment of the environment is mediated by several methods, of which the application depends not only on the pollutant sought out, but also on enzyme-linked immunosorbent assay (ELISA), which has an essential role in quantification of biological pollutants. Attempts at expulsion of the different indoor environment pollutants is mediated by indoor environment advisors, whose efforts are aimed at obtaining reliable evaluation and control of indoor air. Implemented as a form of tertiary prevention, their methods are conducive to improved asthma control, in adults as well as children.

RNA viruses alter house dust mite physiology and allergen production with no detected consequences for allergenicity

RNA viruses have recently been detected in association with house dust mites, including laboratory cultures, dust samples, and mite-derived pharmaceuticals used for allergy diagnosis. This study aimed to assess the incidence of viral infection on Dermatophagoides pteronyssinus physiology and on the allergenic performance of extracts derived from its culture. Transcriptional changes between genetically identical control and virus-infected mite colonies were analysed by RNAseq with the support of a new D. pteronyssinus high-quality annotated genome (56.8 Mb, 108 scaffolds, N50 = 2.73 Mb, 96.7% BUSCO-completeness). Extracts of cultures and bodies from both colonies were compared by inspecting major allergen accumulation by enzyme-linked immunosorbent assay (ELISA), allergen-related enzymatic activities by specific assays, airway inflammation in a mouse model of allergic asthma, and binding to allergic patient's sera IgE by ImmunoCAP. Viral infection induced a significant transcriptional response, including several immunity and stress-response genes, and affected the expression of seven allergens, putative isoallergens and allergen orthologs. Major allergens were unaffected except for Der p 23 that was upregulated, increasing ELISA titers up to 29% in infected-mite extracts. By contrast, serine protease allergens Der p 3, 6 and 9 were downregulated, being trypsin and chymotrypsin enzymatic activities reduced up to 21% in extracts. None of the parameters analysed in our mouse model, nor binding to human IgE were significantly different when comparing control and infected-mite extracts. Despite the described physiological impact of viral infection on the mites, no significant consequences for the allergenicity of derived extracts or their practical use in allergy diagnosis have been detected.

Current advances in house dust mite allergen immunotherapy (AIT): Routes of administration, biomarkers and molecular allergen profiling

Allergy to house dust mites (HDM) is a perennial respiratory disease that affect more than half a billion people worldwide. Dermatophagoides pteronyssinus and D. farinae, two HDM species, are major sources of indoor allergens triggering allergic inflammation. Although symptomatic drugs are widely used to block the allergic reaction, allergen immunotherapy is the only curative treatment of IgE-mediated type I respiratory allergies. In this article, we review recent advances in various routes of allergen immunotherapy. We particularly focus on subcutaneous (SCIT) and sublingual (SLIT) immunotherapy, used as a reference therapy since they have transformed allergic treatments by improving symptoms (asthma and rhinitis) as well as the quality of life of patients. We also highlight recent data in more exploratory routes (i.e., oral, intralymphatic, epicutaneous and intradermal) and discuss respective advantages of various route, as well as their foreseen modes of action. Finally, we provide an update on biomarkers as well as on the relevance of the molecular profiling of allergic individuals related to treatment efficacy or asthma prediction.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Recombinant T-cell epitope conjugation: A new approach for Dermatophagoides hypoallergen design

BACKGROUND

Allergen-specific immunotherapy (AIT) is the only clinical approach that can potentially cure some allergic diseases by inducing immunological tolerance. Dermatophagoides pteronyssinus is considered as the most important source of mite allergens worldwide, with high sensitization rates for the major allergens Der p 1, Der p 2 and Der p 23. The aim of this work is to generate a hypoallergenic hybrid molecule containing T-cell epitopes from these three major allergens.

METHODS

The hybrid protein termed Der p 2231 containing T-cell epitopes was purified by affinity chromatography. The human IgE reactivity was verified by comparing those with the parental allergens. The hybrid was also characterized immunologically through an in vivo mice model.

RESULTS

The hybrid rDer p 2231 stimulated in peripheral blood mononuclear cells (PBMCs) isolated from allergic patients with higher levels of IL- 2, IL-10, IL-15 and IFN-γ, as well as lower levels of IL-4, IL-5, IL-13, TNF-α and GM-CSF. The use of hybrid molecules as a therapeutic model in D. pteronyssinus allergic mice led to the reduction of IgE production and lower eosinophilic peroxidase activity in the airways. We found increased levels of IgG antibodies that blocked the IgE binding to the parental allergens in the serum of allergic patients. Furthermore, the stimulation of splenocytes from mice treated with rDer p 2231 induced higher levels of IL-10 and IFN-γ and decreased the secretion of IL-4 and IL-5, when compared with parental allergens and D. pteronyssinus extract.

CONCLUSIONS

rDer p 2231 has the potential to be used in AIT in patients co-sensitized with D. pteronyssinus major allergens, once it was able to reduce IgE production, inducing allergen-specific blocking antibodies, restoring and balancing Th1/Th2 immune responses, and inducing regulatory T-cells.

Differences in mouse strains determine the outcome of Der p 2 allergy induction protocols

In vivo animal models can provide worthy information on various aspects of asthma mechanism and pathogenesis. The genetic predisposition and phenotype of mice may affect the immune response itself. Here we compare the early immune response to Der p 2 or HDM allergen extract upon injection and inhalation in BALB/c and C57BL/6 mice. Female C57BL/6 and BALB/c mice were immunized with Der p 2 allergen subcutaneously followed by inhalation of Der p 2 or HDM extract. After challenge, the mice were euthanized; blood, bronchoalveolar lavage (BAL), spleens and lungs were collected. Cells from BAL were identified by May-Grünwald Giemsa staining and lung leukocyte populations were analyzed by flow cytometry. Serum antibody levels of Der p 2 specific IgE, IgG, IgG1 and IgG2a were assessed by ELISA, and cytokine secretion (IL-4, IFN-γ and IL-10) was evaluated upon stimulation with Der p 2 or HDM extract. The Th2 immune response was confirmed by elevated allergen-specific immunoglobulin E (IgE) and the allergic reaction was evidenced by infiltration of eosinophils and/or neutrophils into BAL. We found that BALB/c mice were inefficient in integrating local with systemic immune response, evidenced by almost no IgG or IgE production upon one subcutaneous injection and subsequent inhalation of Der p 2 allergen; also, the bronchoalveolar lavage infiltrate in these mice consisted of neutrophil infiltration, unlike C57BL/6 mice in which eosinophilic infiltrate predominated. The differences between BALB/c and C57BL/6 mice strains could be exploited for generating different types of responses to the Der p 2 allergen.

Molecular reactivity profiling upon immunotherapy with a 300 IR sublingual house dust mite tablet reveals marked humoral changes towards major allergens

BACKGROUND

Molecular antibody reactivity profiles have not yet been studied in depth in patients treated by sublingual house dust mite (HDM) tablet immunotherapy. Humoral immune responses to a large panel of HDM mite allergens were studied using allergen microarray technology in a subset of clinically defined high and low responder patients from a double-blind placebo-controlled allergen-specific immunotherapy (AIT) trial using sublingual 300 IR HDM tablets.

METHODS

Serum levels of IgE, IgG and IgG₄ to 13 Dermatophagoides pteronyssinus molecules were measured at baseline and after 1-year AIT, using allergen microarrays in 100 subjects exhibiting high or low clinical benefit.

RESULTS

Der p 1, Der p 2 and Der p 23 were the most frequently recognized allergens in the study population. Patients with HDM-related asthma had significantly higher allergen-specific IgE levels to Der p 1 and Der p 23. No significant difference in the distribution of allergen sensitization pattern was observed between high and low responders. An increase in serum allergen-specific IgG and IgG₄ occurred upon AIT, in particular to allergens Der p 1, Der p 2 and Der p 23 (p < 0.0001).

CONCLUSIONS

We confirm for our study population that Der p 1- and Der p 23-specific IgE levels are associated with asthma. IgE reactivity profiles were not predicitive of sublingual AIT outcomes, with 300 IR tablets as efficacious in pauci- and multi-sensitized subjects. Our study is the first to demonstrate the induction of IgG and IgG₄  specific for the HDM allergens Der p 1, Der p 2 and Der p 23 by sublingual AIT.

Human IgE monoclonal antibody recognition of mite allergen Der p 2 defines structural basis of an epitope for IgE cross-linking and anaphylaxis in vivo

Immunoglobulin E (IgE) antibody is a critical effector molecule for adaptive allergen-induced immune responses, which affect up to 40% of the population worldwide. Allergens are usually innocuous molecules but induce IgE antibody production in allergic subjects. Allergen cross-linking of IgE bound to its high affinity receptor (FcεRI) on mast cells and basophils triggers release of histamine and other mediators that cause allergic symptoms. Little is known about the direct allergen-IgE antibody interaction due to the polyclonal nature of serum IgE and the low frequency of IgE-producing B cells in blood. Here, we report the X-ray crystal structure of a house dust mite allergen, Der p 2, in complex with Fab of a human IgE monoclonal antibody (mAb) isolated by hybridoma technology using human B cells from an allergic subject. This IgE mAb, 2F10, has the correct pairing of heavy and light chains as it occurs in vivo. Key amino acids forming the IgE epitope on Der p 2 were identified. Mutation of these residues ablated their functional ability to cross-link IgE in a mouse model of passive systemic anaphylaxis. These analyses revealed an important conformational epitope associated with the IgE antibody repertoire to a major mite allergen.

Correlation between sensitization to house dust mite major allergens, age, and symptoms in Japanese house dust mite allergic subjects

Der p 23 has recently been recognized as a new house dust mite (HDM) major allergen that may be linked to the development of asthma in HDM allergic patients. This study aimed to investigate the frequency of sensitization to HDM major allergen components including Der p 23 and to examine the correlation between HDM-sensitization and AR symptom score in Japanese HDM allergic rhinitis (AR) patients without allergic asthma. Serum samples (n = 120) collected from Japanese HDM AR patients (12 to 64 years) without asthma were assessed for allergen-specific IgE (s-IgE) by ImmunoCAP (Dermatophagoides pteronyssinus (D. pteronyssinus; Der p) extract, Der p 23) or immunosolid-phase allergen chip (Der p 1, Der p 2). Japanese HDM AR patients without asthma showed a high prevalence of allergic sensitization to the HDM major allergens Der p 1 (94.2%), Der p 2 (97.5%) and Der p 23 (71.7%). No difference in the prevalence was detected for Der p 1 and Der p 2 s-IgE among three age groups. However, the prevalence of Der p 23 s-IgE was significantly higher in the younger group compared to the elderly group. No significant correlation was found between AR symptom scores and concentration of s-IgE towards Der p extract and any of the three HDM major allergens. Although the prevalence of sensitization towards D. pteronyssinus major allergens is high in Japanese AR patients without asthma, there was no correlation between allergen specific IgE including IgE towards Der p 23 and AR symptom in this population.

Molecular Profile of Specific IgE to Allergenic Components in Allergic Adults Using Allergen Nano-Bead Array

BACKGROUND

An increasing interest in the field of molecular diagnosis of allergy has been developed in recent years and it goes to be as the routine in-vitro protocol in allergy diagnosis. Friendly Allergen Nano-bead Array (FABER) is a new multiplex assay for the evaluation of specific IgE against 244 allergens including whole extracts and allergenic molecules. The research intended to assess the pattern of IgE sensitization to allergenic components of allergens in allergic adults using FABER 244.

METHODS

Sixty patients with allergic diseases entered this cross-sectional study. Specific IgE to 122 whole allergens extracts and 122 allergenic components was assessed using an allergen nano-bead array (FABER) for all patients. This test includes inhalant and food allergens.

RESULTS

Thirty-seven patients were male (61.7%). The mean (SD) age of patients was 30.73(±6.87) years. As the allergen nano-bead array results showed, Lolium perenne (63.3%), Phleum pretense (60%), and Platanus acerifolia (51.7%) were considered as the most common IgE-sensitizations to the aeroallergen extracts. Moreover, Lol p 1, Phl p 1.0102, and Cup a 1 were found as the most frequent allergenic components in our allergic patients. Among protein families, CCD bearing proteins, expansin, cysteine protease, and profilin families illustrated the highest allergic sensitization.

CONCLUSIONS

The results of the present study demonstrated that despite the higher prevalence of sensitization to Salsola kali (47.2%) using extract-based assays in the previous phase of this research, allergenic components of grasses (Lol p 1, Phl p 1.0102), Cup a 1 as well as Sal k1 as the major components of Cupressuss arizonica and Salsola kali showed the higher sensitization, respectively in adults' allergic patients using FABER test.

Inter-laboratory comparison of semiquantitative allergen-specific Immunoglobulin E test: 7 years of experience in Korea

INTRODUCTION

Multiple allergen simultaneous test (MAST) is widely used as a screening tool for allergic diseases and has the advantage of providing specific IgE (sIgE) results for various allergens in semiquantitative class. We have continuously conducted external quality assessment (EQA) since 2012 for clinical laboratories performing MAST using AdvanSure allergy screen test (LG CHEM, Korea). This study provides an account of the EQA experience.

METHODS

Samples were prepared using pooled sera collected from patients with suspected allergic disease and sent to each laboratory twice a year. Each round included 4-6 serum samples with sIgE for 10-20 inhaled or food allergens. The acceptable class value was the most frequently reported MAST class ±1 titer that exceeded 80% of the total laboratory results.

RESULTS

The average number of participating laboratories was 76 (49-90) and the average response rate was 97.3% during the entire survey period. The acceptable rates were consistently high at 97.7% ± 3.7%. Of the total 537 trials, 18 trials (3.4%) were regarded as nonconsensus results, in which acceptable answers did not exceed 80%. For unacceptable results, the false-negative rate (1.5% ± 2.8%) was higher than the false-positive rate (0.8% ± 2.7%) (p < 0.001). MAST class results were correlated with quantitative IgE results by ImmunoCAP (Spearman's correlation coefficient of 0.682 (p < 0.001) and gamma index of 0.777 (p < 0.001).

CONCLUSION

Although EQA for MAST showed a high level of acceptable answer, some allergen assays require harmonization. Continuous performance of systematic EQA is needed to improve the accuracy of sIgE assays and quality control in clinical laboratories.

House Dust Mite Precision Allergy Molecular Diagnosis (PAMD@) in the Th2-prone Atopic Dermatitis Endotype

Atopic dermatitis (AD) endotyping might be important for developing personalized diagnostic and therapeutic strategies to the different phenotypes. The current study investigated the IgE molecular profile to Dermatophagoides pteronyssinus (D. pteronyssinus) in a subset of patients afflicted with varying severity stages of atopic dermatitis in a subtropical region subjected to a high perennial house dust mite (HDM) exposure. We selected patients showing a clinically relevant sensitization to HDM with mild-to-moderate and severe AD according to their basal Severity Scoring Atopic Dermatitis (SCORAD) index. Skin prick test (SPT) with standardized mite extracts, as well as a Precision Allergy Molecular Diagnosis (PAMD@) panel including nine different D. pteronyssinus allergens and the related protein allergenic characterization, were assessed in all serum samples. A total of 80 European American AD patients with the marked T2 endotype confirmed their eligibility for the study. Major allergens (Der p 23, Der p 2, and Der p 1) were present in more than 86% of all subjects, with mid-tier allergens (Der p 5, Der p 7, and Der p 21) reaching up to 65%. A serodominant role for Der p 11 could not be quantitatively confirmed in the present cohort. The proposed component resolved diagnosis (CRD) panel appeared to be sufficient to obtain a precise D. pteronyssinus molecular diagnosis in AD patients subjected to a climate-dependent high-mite allergen exposure. The raised seroprevalence of IgE response to Der p 23 confirmed this constituent as a major D. pteronyssinus allergen in severe stages of atopic dermatitis. A clinically driven molecular approach appears to be essential to frame a more precise diagnosis and therapy of this heterogeneous allergic condition.

The Dynamics of Mycobiota Development in Various Types of Wood Dust Depending on the Dust Storage Conditions

Solid or processed wood, and wood waste in particular (dust, shavings, etc.) are the source of a number of health hazards for workers in the wood industry. One of the many negative health effects of exposure to fungi is allergic diseases caused by hypersensitivity reactions. The aim of this study was to investigate the effect of wood species and the degree of dust fragmentation, resulting from processing conditions and storage conditions on the level of wood dust contamination with microscopic fungi during 1 year of storage. An additional aspect of the research was the assessment of the influence of the antioxidant wood bioactive compounds on the development of A. alternata microscopic fungi. It was found that the conditions in which wood dust is stored significantly affect the development of microscopic fungi, especially fungi of the genus Alternaria. The results indicate that temperature is the determining factor, not the relative humidity of the air. The degree of dust fragmentation resulting from the sanding paper grit also has a significant impact on the development of microscopic fungi. Finer dust is more susceptible to the development of microscopic fungi. The antioxidant activity of the wood from which the dust was formed was found to have a significant impact on the development of microscopic fungi. An inverse relationship was observed, indicating the strong activity of antimicrobial substances. Gaining comprehensive knowledge of how all factors affect each other is a key step in understanding the risk and implementing measures to prevent and protect the work environment.

Cut-off value of D. pteronyssinus specific IgE in double negative patients Der p 1 and Der p 2 and its clinical repercussion

Accessibility to more precise diagnostic techniques such as component resolved diagnostics (CRD), provides us with an important advance in diagnostic aspects as well as treatment. The subject of this study aims to better understand the profiles of sensitization to Der p 1, Der p 2 and Der p 23 and to know to what extent their use could help us in optimizing the decision-making for their treatment with Specific Immunotherapy. Cross-sectional study of subjects older than 5 years, diagnosed with allergy to HDM using skin prick test and sIgE, with symptoms of rhinitis and/or asthma. Total and specific IgE was determined to D. pteronyssinus, nDer p 1, rDer p 2 and rDer p 23 using ImmunoCAP. 240 patients were recruited (97.1% rhinitis and 46.25% rhinitis and asthma). Four different phenotypes were observed: positive or negative for sIgE nDer p 1 and/or IgE rDer p 2. 17% of these patients sIgE were double negative for Der p 1 and Der p 2 (increasing with age and with significantly lower sIgE levels than the rest of the groups). Using ROC curves, value less than 2.18 KUA/L for D. pteronyssinus sIgE gave us a sensitivity and specificity of 0.882 and 0.985, respectively, to double negative IgE nDer p 1 and IgE rDer p 2 group. Despite positive SPT and sIgE to D. pteronyssinus, 17% of the studied population is IgE nDer p 1 and IgE rDer p 2 double negative, with a cut-off value of 2.18 KU/L, which is very relevant for taking of decisions in prescription of AIT. The double positive population sIgE nDer p 1 and IgE rDer p 2 is associated with asthma compared to the other groups and this does not seem to be influenced by IgE rDer p 23.

Der p 38 Is a Bidirectional Regulator of Eosinophils and Neutrophils in Allergy

The house dust mite is the most common cause of allergic diseases, and TLR4 acts as an overarching receptor for allergic responses. This study aimed to identify novel allergen binding to TLR4 in house dust mites and unveil its unique role in allergic responses. Der p 38 was purified and characterized by liquid chromatography tandem mass spectrometry-based peptide mapping. Biolayer interferometry and structure modeling unveiled TLR4-binding activity and the structure of recombinant Der p 38. The allergenicity of Der p 38 was confirmed by a skin prick test, and basophil activation and dot blot assays. The skin prick test identified 24 out of 45 allergic subjects (53.3%) as Der p 38⁺ subjects. Der p 38-augmented CD203c expression was noted in the basophils of Der p 38⁺ allergic subjects. In animal experiments with wild-type and TLR4 knockout BALB/c mice, Der p 38 administration induced the infiltration of neutrophils as well as eosinophils and exhibited clinical features similar to asthma via TLR4 activation. Persistent Der p 38 administration induced severe neutrophil inflammation. Der p 38 directly suppressed the apoptosis of allergic neutrophils and eosinophils, and enhanced cytokine production in human bronchial epithelial cells, inhibiting neutrophil apoptosis. The mechanisms involved TLR4, LYN, PI3K, AKT, ERK, and NF-κB. These findings may contribute to a deep understanding of Der p 38 as a bridge allergen between eosinophilic and neutrophilic inflammation in the pathogenic mechanisms of allergy.

Precision Medicine in Mite Allergic Rhinitis

It is well-known that a correct diagnosis is necessary for effective treatment. In the case of allergic rhinitis due to mites, imprecise diagnosis with effective but improvable methods means that in many cases an optimal result is not reached in patients. The diagnosis of allergic rhinitis due to mite sensitization have to require more homogeneously reproducible diagnostic tests that try to encompass many more of the protein antigens contained in them. With the few proteins that the problem has usually focused on, there is no they would cover many of the clinically relevant allergens in a large proportion of patients. In this mini-review we try to highlight the importance of having good allergenic sources and briefly gather information on various allergenic proteins included in mites that could be clinically relevant. All this to try to get closer to a more accurate diagnosis. We are also talking about two diagnostic tools that are clearly out of use and that should be promoted in the consultations to obtain an even greater and better outcome in patients.

The Acari Hypothesis, II: Interspecies Operability of Pattern Recognition Receptors

Hypersensitivity to galactose-α-1,3-galactose (α-gal) is an informative example of a pathologic IgE-mediated process. By way of their saliva, ticks are able to sensitize humans to tick dietary elements that express α-gal. Mites, which along with ticks constitute the phyletic subclass Acari, feed on proteinaceous foodstuffs that represent most, if not all, human allergens. Given: (1) the gross nature of the pathophysiological reactions of allergy, especially anaphylaxis, (2) the allergenicity of acarian foodstuffs, and (3) the relatedness of ticks and mites, it has been hypothesized that human-acarian interactions are cardinal to the pathogenesis of allergy. In this report, a means by which such interactions contribute to that pathogenesis is proposed.

An international seroprevalence survey of the IgE sensitisation to the Dermatophagoides farinae house dust mite and two of its major allergens (Der f 2, Zen 1) in atopic dogs

BACKGROUND

Dogs with atopic dermatitis are often immunoglobulin (Ig)E-sensitised to Dermatophagoides farinae (Df) house dust mites, yet limited data exist on the sensitisation rates to the individual Df allergens, Der f 2 and Zen 1.

OBJECTIVES

To determine the IgE sensitisation rates to Df, Der f 2 and Zen 1 in atopic dogs from geographically diverse countries.

ANIMALS

Serum was collected from 32 laboratory dogs in Japan, and 837 atopic dogs from 11 countries from five continents: Asia (Japan, Thailand, Taiwan), Europe (Italy, Latvia, the Netherlands, UK), North America (USA), South America (Argentina, Brazil) and Africa (South Africa).

METHODS AND MATERIALS

We determined Df-, Der f 2- and Zen 1-specific IgE levels by ELISA. Correlations between the IgE values for these three allergens were calculated.

RESULTS

The IgE seropositivity rates for Df varied between 74% (Argentina) and 100% (the Netherlands, Thailand, South Africa), those for Der f 2 between 12% (Argentina) and 88% (South Africa), and for Zen 1 between 70% (Argentina) and 100% (the Netherlands). Apart from the especially low seropositivity rate for Der f 2-specific IgE in Argentina, the percentage of IgE sensitisation varied little between countries. There was significant correlation between the IgE levels to these three allergens which was highest between Df and Zen 1, and lowest between Zen 1 and Der f 2.

CONCLUSIONS AND CLINICAL RELEVANCE

The IgE sensitisation to Df is geographically widespread. Der f 2 and Zen 1 are major allergens for dogs in almost all countries where this was evaluated.

Der f 38 Is a Novel TLR4-Binding Allergen Related to Allergy Pathogenesis from Dermatophagoides farinae

It is difficult to treat allergic diseases including asthma completely because its pathogenesis remains unclear. House dust mite (HDM) is a critical allergen and Toll-like receptor (TLR) 4 is a member of the toll-like receptor family, which plays an important role in allergic diseases. The purpose of this study was to characterize a novel allergen, Der f 38 binding to TLR4, and unveil its role as an inducer of allergy. Der f 38 expression was detected in the body and feces of Dermatophagoides farinae (DF). Electron microscopy revealed that it was located in the granule layer, the epithelium layer, and microvilli of the posterior midgut. The skin prick test showed that 60% of allergic subjects were Der f 38-positive. Der f 38 enhanced surface 203c expression in basophils of Der f 38-positive allergic subjects. By analysis of the model structure of Der p 38, the expected epitope sites are exposed on the exterior side. In animal experiments, Der f 38 triggered an infiltration of inflammatory cells. Intranasal (IN) administration of Der f 38 increased neutrophils in the lung. Intraperitoneal (IP) and IN injections of Der f 38 induced both eosinophils and neutrophils. Increased total IgE level and histopathological features were found in BALB/c mice treated with Der f 38 by IP and IN injections. TLR4 knockout (KO) BALB/c mice exhibited less inflammation and IgE level in the sera compared to wild type (WT) mice. Der f 38 directly binds to TLR4 using biolayer interferometry. Der f 38 suppressed the apoptosis of neutrophils and eosinophils by downregulating proteins in the proapoptotic pathway including caspase 9, caspase 3, and BAX and upregulating proteins in the anti-apoptotic pathway including BCL-2 and MCL-1. These findings might shed light on the pathogenic mechanisms of allergy to HDM.

Contribution of cysteine and serine proteases to proteolytic digestion in an allergy-eliciting house dust mite

The digestive physiology of house dust mites (HDM) is of interest to understand their allergenicity towards humans since many of their allergens are digestive enzymes and/or are excreted into airborne fecal pellets. The aim of this study is to provide insight on the biochemical basis of proteolytic digestion in Dermatophagoides pteronyssinus, the most widespread HDM species. First, assays using non-specific protein substrates on purified fecal and body extracts determined that body-associated activity is almost exclusively dependent on cysteine proteases, and specifically on major allergen Der p 1. By contrast, cysteine and serine proteases contributed similarly to the activity estimated on fecal extracts. Second, the screening of group-specific peptide-based protease inhibitors followed by ingestion bioassays revealed that the human skin-derived cysteine protease inhibitor cystatin A produces a significant reduction in mite feeding (i.e. excreted guanine), and triggers the overproduction of Der p 1 (3-fold increase by ELISA). Noteworthy, the inhibition of cysteine proteases by cystatin A also resulted in a reduction in three non-target serine protease activities. Further incubation of these extracts with exogenous Der p 1, but not with other commercial cysteine proteases, restored trypsin (Der p 3) and chymotrypsin (Der p 6) activities, indicating that Der p 1 is responsible for their activation in vivo. Finally, the role of serine proteases on the mite's digestive physiology is discussed based on their remarkable activity in fecal extracts and the autocoprophagic behavior reported in mites in this study.

Comparison of house dust mite sensitization profiles in allergic adults from Canada, Europe, South Africa and USA

BACKGROUND

Sensitization to house dust mite (HDM) is a leading cause of allergic rhinitis and asthma. Despite more than 30 HDM-derived allergens having been identified to date, specific therapeutic approaches do not yet take into account the local sensitization profiles of patients. This study aimed to identify patterns of HDM sensitization in HDM-allergic adults living in distinct geographic areas, to inform the development of targeted diagnostic and therapeutic tools.

METHODS

Serum samples from 685 HDM-allergic subjects from Canada, Europe, South Africa, and the USA were tested for levels of IgE specific for 17 micro-arrayed HDM allergens by ImmunoCAP Immuno Solid-phase Allergen Chip (ISAC) technology.

RESULTS

The results confirmed significant geographical variability in sensitization patterns and levels of IgE. In all areas, the major sensitizers were the group 1 and group 2 allergens and Der p 23. Der p 23 was a frequent sensitizer: 64% of the subjects had IgE specific for Der p 23, and 2.3% were monosensitized to it. In South Africa, Der p 23 was the dominant HDM allergen (86% prevalence) and Der p 7 achieved major allergen status (56%). IgE sensitization to HDM was influenced by asthmatic status, levels of allergen exposure, age, race-ethnicity and smoking status, but not by BMI.

CONCLUSION

Sensitization profiles to HDM allergens differ considerably among distinct geographic areas, with Der p 7 and Der p 23 being major sensitizers in South Africa. Such heterogeneity should be taken into account in the diagnosis and treatment of HDM-allergic patients.

Perspectives in Allergen-Specific Immunotherapy: Molecular Evolution of Peptide- and Protein-Based Strategies

Allergen-specific Immunotherapy (AIT), through repetitive subcutaneous or sublingual administrations of allergen extracts, represents up to now the unique treatment against allergic sensitizations. However, the clinical efficacy of AIT can be largely dependent on the quality of natural allergen extracts. Moreover, the long duration and adverse side effects associated with AIT negatively impact patient adherence. Tremendous progress in the field of molecular allergology has made possible the design of safer, shorter and more effective new immunotherapeutic approaches based on purified and characterized natural or recombinant allergen derivatives and peptides. This review will summarize the characteristics of these different innovative vaccines including their effects in preclinical studies and clinical trials.

Temperature stress response: A novel important function of Dermatophagoides farinae allergens

Dermatophagoides farinae, an important pathogen, has multiple allergens. However, their expression under physiological conditions are not understood. Our previous RNA-seq showed that allergens of D. farinae were up-regulated under temperature stress, implying that they may be involved in stress response. Here, we performed a comprehensive study. qRT-PCR detection indicated that 26 of the 34 allergens showed differential expression. Der f1 had the most abundant basic expression quantity. Der f 28.0201 (HSP70) and Der f3 had the same regulation pattern in 9 highly expressed transcripts, which only up-regulated at 41 °C and 43 °C, but Der f 28.0201 showed stronger regulation than Der f 3 (19.88-fold vs 6.02-fold). Whereas Der f 1, 2, 7, 21, 22, 27, and 30 were up-regulated under both heat and cold stress, and Der f 27 showed the strongest regulation ability among them. Der f 27 showed more significant up-regulation than Der f 28.0201 under heat stress (23.59-fold vs 19.88-fold), and Der f27 had more obvious up-regulation under cold than heat stress (30.70-fold vs 23.59-fold). The expression of Der f 27, 28.0201 and 1, and D. farinae survival rates significantly decreased following RNAi, indicating the upregulation of these allergens under temperature stress conferred thermo-tolerance or cold-tolerance to D. farinae. In this study, we described for the first time that these allergens have temperature-stress response functions. This new scientific discovery has important clinical value for revealing the more frequent and serious allergic diseases caused by D. farinae during the change of seasons.

Mite Molecular Profile in the Th2-Polarized Moderate-to-Severe Persistent Asthma Endotype Subjected to High Allergen Exposure

BACKGROUND

The association among the IgE responses to prevailing groups of house dust mite (HDM) allergens in the concurrent asthma phenotypes has not been determined.

OBJECTIVE

The aim of the present study lays on a component-resolved diagnosis (CRD) model to investigate the mite molecular signature in subjects with type-2 inflammation asthma.

METHODS

We selected patients showing a clinically relevant sensitization to HDMs with moderate-to-severe persistent asthma. Skin prick test (SPT) with standardized mite extracts, a broad customized CRD serum sIgE panel including 9 Dermatophagoides pteronyssinus allergens and the related protein allergenic characterization, was investigated in all serum samples.

RESULTS

Ninety out of 93 (96.77%) patients with a positive SPT to HDM showed a concordant sIgE (≥0.35 kUA/L) to the crude extract of D. pteronyssinus. Major allergens (Der p 2, Der p 23, and Der p 1) were present in >70% of all subjects, with mid-tier allergens (Der p 5, Der p 7, and Der p 21) reaching up to 51% in the present cohort. A complex pleomorphic repertoire of HDM molecules recognized by IgE was depicted, including 38 distinct profiles.

CONCLUSIONS AND CLINICAL RELEVANCE

The proposed CRD panel approach, containing the most prevalent HDM allergens, appeared to be sufficient to obtain a precise D. pteronyssinus molecular diagnosis in asthmatics with a climate-dependent high-mite allergen exposure and coexisting sensitization. A dominant role of both major and mid-tier allergens has been confirmed in moderate and severe persistent asthmatics with the preponderant Th2-high endotype.

Mapping Human Monoclonal IgE Epitopes on the Major Dust Mite Allergen Der p 2

IgE Abs drive the symptoms of allergic disease upon cross-linking allergens on mast cells or basophils. If the IgE binding sites on the allergens could be identified, it may be useful for creating new forms of immunotherapy. However, direct knowledge of the human IgE (hIgE) epitopes is limited because of the very low frequency of IgE-producing B cells in blood. A new hybridoma technology using human B cells from house dust mite-allergic patients was used to identify four Der p 2-specific hIgE mAbs. Their relative binding sites were assessed and compared by immunoassays with three previously studied murine IgG mAbs. Immunoassays showed that the recognition of Der p 2 by the first three hIgE was inhibited by a single murine IgG, but the fourth hIgE recognized a different epitope from all the other mAbs. The functional ability of the hIgE that bind different epitopes to cross-link Der p 2 was demonstrated in a mouse model of passive systemic anaphylaxis. Nuclear magnetic resonance analyses of Der p 2 in complex with IgG and IgE Abs were used to identify specific residues in the epitopes. To our knowledge, the combination of immunoassays to distinguish overlapping epitopes and nuclear magnetic resonance analyses to identify specific residues involved in Ab binding provided the first epitope mapping of hIgE mAbs to an allergen. The technologies developed in this study will be useful in high-resolution mapping of human epitopes on other Ags and the design of improved therapeutics.

A 300 IR sublingual tablet is an effective, safe treatment for house dust mite-induced allergic rhinitis: An international, double-blind, placebo-controlled, randomized phase III clinical trial

BACKGROUND

Allergic rhinitis induced by house dust mites (HDMs) is a highly prevalent but often underdiagnosed and undertreated/untreated chronic disease. It often has a negative impact on sleep, work, leisure activities, and health-related quality of life. Allergen immunotherapy is a proven, safe treatment for respiratory allergies.

OBJECTIVE

We sought to assess the efficacy and safety of a 300 index of reactivity (IR) sublingual tablet formulation of Dermatophagoides pteronyssinus:Dermatophagoides farinae 1:1 extract in adolescents (aged ≥12) and adults with moderate to severe HDM-induced allergic rhinitis.

METHODS

In a phase III, international, double-blind, placebo-controlled, randomized clinical trial, participants received approximately 12 months of treatment with placebo or the 300 IR tablet. The primary end point was the average total combined score during 4 weeks at the end of the treatment period.

RESULTS

A total of 1607 participants were randomized, and 1476 (including 555 [37.6%] with concomitant mild controlled asthma at inclusion) comprised the full analysis set. Over the primary evaluation period, the least squares mean average total combined score in the 300 IR group (3.62) was significantly lower (P < .0001) than in the placebo group (4.35), with a relative least squares mean difference of -16.9% (95% CI, -24.0% to -9.2%). All prespecified secondary end points were consistently improved in the 300 IR group, relative to placebo. The 300 IR tablet was generally well tolerated. Treatment-related adverse events (mainly mild or moderate local reactions) were reported for 51.0% of the patients in the 300 IR group and 14.9% in the placebo group.

CONCLUSIONS

The 300 IR sublingual HDM tablet is an effective, safe treatment for HDM-induced allergic rhinitis.

Sensitization to major Dermatophagoides pteronyssinus allergens in house dust mite allergic patients from North Eastern Poland developing rhinitis or asthma

PURPOSE

Recognition of individual allergens by IgE is crucial for triggering symptoms in allergic rhinitis (AR) or asthmatic (AA) patients. House dust mite (HDM) allergy is frequent around the world, the sensitization profile to individual HDM allergens varies in individual HDM-allergic patients (APs). The aim of this study was to evaluate the pattern of IgE sensitization to three major Dermatophagoides pteronyssinus (Dp) allergens among patients from North Eastern Poland suffering from HDM-AR and/or AA.

PATIENTS AND METHODS

The study was performed on 323 HDM-AR and/or AA patients and 106 controls (CG) including 30 healthy non-atopic subjects, 32 AR patients not sensitized to Dp and 44 non-atopic asthmatics. IgE levels to natural (n)Der p 1, nDer p 2, recombinant (r)Der p 2.0101 and rDer p 23 allergens were measured by ELISA.

RESULTS

The majority of HDM-APs were sensitized to nDer p 1 (72.1%), nDer p 2 (81.7%), rDer p 2.0101 (78.3%) and rDer p 23 (70.9%). The frequency of positive results to individual allergens depended on clinical manifestations and the level of IgE to the whole Dp extract. In HDM-AA patients, reactivity to nDer p 1 and rDer p 23 was detected more frequently than in HDM-AR patients. The whole Dp extract completely inhibited IgE binding to nDer p 1 and nDer p 2 but only partially to rDer p 23.

CONCLUSIONS

HDM-APs from North-Eastern Poland display sensitization profile to major allergens which is similarly observed in western Europe. HDM-based diagnostic and therapeutic products should include all major allergens.

Depiction of Major Mite Allergens in Severe Allergic Rhinitis with High Mite Perennial Exposure

Objective

Airway diseases, including allergic rhinitis, are prompted by specific IgE antibodies against airborne allergens and notably those derived from mites. The presented study focused on the specific IgE immediate response to Dermatophagoides pteronyssinus (D. pteronyssinus) mite major allergens and the corresponding pertinence of molecular diagnosis in patients bothered with severe persistent rhinitis.

Methods

Individuals exhibiting confirmed sensitization to D. pteronyssinus along with a clinical diagnosis of coexisting severe allergic rhinitis were included in the study. In vivo investigations encompassed intradermal testing with a battery of standardized allergenic extracts, concurrent with in vitro specific IgE to the crude extract of D. pteronyssinus, and associated individual molecular allergens were assessed.

Results

Fifty-five out of 59 subjects showed serodominant IgE responses to the major allergens Der p 1, Der p 2 and Der p 23. Both Der p 2 and Der p 23 reached a prevalence above 80%, while group 10 allergen tropomyosin was scarcely depicted (<10%) and exclusively present in younger individuals.

Conclusion

The proposed component-resolved diagnosis panel accurately recognized 93.22% of D. pteronyssinus allergic patients. The raised seroprevalence of IgE response to Der p 23 also confirmed this constituent as a major D. pteronyssinus allergen in severe allergic rhinitis. A molecular approach appears to be essential to frame a more precise diagnosis and eventually a personalized immunotherapy regarding this allergic condition.

Detection of allergen-specific antibody-secreting cells in dogs by ELISPOT

Current laboratory tests are unable to distinguish healthy from allergic dogs. Unlike serum antibody responses, circulating antibody-secreting cells (ASC) are temporarily induced after each contact with the antigen. These ASC can be identified using ELISPOT and the observation of allergen-specific ASC might correlate with the causative allergens in dogs with an allergic dermatitis. In this study, blood was sampled from six privately-owned allergic dogs and six non-allergic laboratory beagles to determine the frequency of circulating allergen-specific ASC for common allergens. Blood IgE+, IgA + and IgG + cells were magnetically isolated to determine the number of allergen-specific ASC with ELISPOT for Dermatophagoides farinae, Dermatophagoides pteronyssinus, Alternaria alternata, birch, timothy grass, wheat, cow's milk, bovine, chicken and lamb meat. For IgA and IgG, allergen-specific spots were observed, however for IgE, no spots were detected for any of the allergens. ELISPOT could not differentiate allergic from non-allergic dogs. When the responses to the different allergens were compared, more IgA ASC for D. pteronyssinus were observed compared to some of the other allergens which was statistically significant for the non-allergic dogs and approached significance in the allergic dogs. These findings indicate that ELISPOT can be used to identify circulating allergen-specific IgA- and IgG-secreting cells. The technique did however not detect allergen-specific IgE ASC and was unable to distinguish allergic from non-allergic dogs. Only a small number of studies have studied allergen-specific IgA in dogs. The finding that dogs have higher numbers of D. pteronyssinus-specific IgA ASC points out that apart from IgE and IgG, it might be interesting to include IgA measurements for certain allergens to analyse the complete spectrum of both the protective and pro-allergic antibody responses.

EAACI Allergen Immunotherapy User's Guide

Allergen immunotherapy is a cornerstone in the treatment of allergic children. The clinical efficiency relies on a well-defined immunologic mechanism promoting regulatory T cells and downplaying the immune response induced by allergens. Clinical indications have been well documented for respiratory allergy in the presence of rhinitis and/or allergic asthma, to pollens and dust mites. Patients who have had an anaphylactic reaction to hymenoptera venom are also good candidates for allergen immunotherapy. Administration of allergen is currently mostly either by subcutaneous injections or by sublingual administration. Both methods have been extensively studied and have pros and cons. Specifically in children, the choice of the method of administration according to the patient's profile is important. Although allergen immunotherapy is widely used, there is a need for improvement. More particularly, biomarkers for prediction of the success of the treatments are needed. The strength and efficiency of the immune response may also be boosted by the use of better adjuvants. Finally, novel formulations might be more efficient and might improve the patient's adherence to the treatment. This user's guide reviews current knowledge and aims to provide clinical guidance to healthcare professionals taking care of children undergoing allergen immunotherapy.

Efficacy and safety of sublingual dust mite drops in children with mono- or polysensitized allergic rhinitis

OBJECTIVE

To explore the efficacy and safety of sublingual house dust mite (HDM) drops in children with mono- or polysensitized allergic rhinitis.

METHODS

We conducted a retrospective cohort study of 65 children with monosensitized AR and 118 children with polysensitized AR who were scheduled for sublingual administration of HDM drops from January 2015 to June 2016. Interleukin (IL)-2, IL-4, and IL-17α, transforming growth factor-β1 (TGF-β1), specific immunoglobulin E (IgE), and specific IgG4 were detected by ELISA. The efficacies were assessed using symptoms score and medication score. All the outcomes were measured 1 month before the study and 1 month after the end of the 2-year treatment.

RESULTS

The total nasal symptoms score (TNSS) decreased significantly from 11.27 (9.81 ± 12.73) at baseline to 3.48(1.98 ± 4.98) at the end of sublingual treatment for the monosensitized AP group (t = 30.00, P < 0.01), and from 11.54(10.04 ± 13.04) to 3.56 (2.00 ± 5.16) for the polysensitized AR group (t = 40.05, P < 0.01), respectively. IL-2 and TGF-β1 increased significantly after treatment in contrast with before treatment in both the monosensitized group and the polysensitized group (both P < 0.01). In contrast, IL-4 and IL-17α decreased significantly after treatment compared with the baseline in both groups (both P < 0.01). Sublingual HDM drops were generally safe and well tolerant in both groups.

CONCLUSIONS

This study confirmed the efficacy and safety of sublingual AIT in both monosensitized and polysensitized AR patients (Chinese children).

An Engineered Hybrid Protein from Dermatophagoides pteronyssinus Allergens Shows Hypoallergenicity

The house dust mite (HDM) Dermatophagoides pteronyssinus is an important risk factor for asthma and rhinitis. Allergen specific immunotherapy that is based on recombinant proteins has been proposed for the safer and more efficient treatment of allergic diseases. The aim of this study was to design and obtain a hybrid protein (DPx4) containing antigenic regions of allergens Der p 1, Der p 2, Der p 7, and Der p 10 from this mite. DPx4 was produced in Escherichia coli and its folding was determined by circular dichroism. Non-denaturing dot-blot, ELISA, basophil activation test, dot blot with monoclonal antibodies, ELISA inhibition, and cysteine protease activity assays were performed. Mice that were immunized with DPx4 were also analyzed. We found that DPx4 had no cysteine protease activity and it showed significantly lower IgE reactivity than Der p 1, Der p 2, and D. pteronyssinus extract. DPx4 induced lower basophil activation than Der p 2 and the allergen extract. Immunized mice produced IgG antibodies that inhibited the binding of allergic patient’s IgE to the allergen extract and induced comparatively higher levels of IL-10 than the extract in peripheral blood mononuclear cells (PBMC) culture. These results suggest that DPx4 has immunological properties that are useful for the development of a mite allergy vaccine.

Recent developments and highlights in rhinitis and allergen immunotherapy

This review paper aims to provide an overview of recent developments in the field of allergic and non-allergic rhinitis, as well as allergen immunotherapy. Recent advances in phenotyping and endotyping various forms of rhinitis have brought us one step closer towards tailoring treatment more appropriately for a given patient. Updates on local allergic rhinitis are also covered. Allergen immunotherapy (AIT) is an area of significant interest, with multiple original papers and recent position papers and guidelines published. Evidence related to the application of AIT in seasonal and perennial allergic rhinitis (AR), local allergic rhinitis and novel and expanded applications is discussed in the publication.

Newly designed hemagglutinin-Der p 2 chimera is a potential candidate for allergen specific immunotherapy

Aim To investigate the immunomodulatory potential of a chimera composed of the receptor-binding domain of hemagglutinin 1 (H1s) from Influenza virus and Der p 2 (D2) allergen for allergen-specific immunotherapy of house-dust mite allergy (HDM).

MAIN METHODS

H1sD2 chimera and D2 allergen were produced by genetic engineering in E. coli. Recombinant antigens were extracted from inclusion bodies by urea, then refolded and purified by immobilized- metal affinity chromatography (IMAC). Purity was verified by 2D-PAGE and secondary structures were assessed by CD spectroscopy. IgE reactivity of H1sD2 and D2 was tested in western blot with sera from 8 persons with clinical history of HDM allergy. Immunogenicity of H1sD2 and D2 were analyzed in Balb/c mice. Cytokine profile was analyzed by ELISA after stimulation of mouse spleen cells with H1sD2 and D2. Leukocyte population abundance of cells isolated from spleen and lymph node was assessed by flow cytometry.

KEY FINDINGS

Purified recombinant proteins H1sD2 (42 kDa) and D2 (15 kDa) revealed well defined secondary structures, and preserved IgE reactive epitopes. Analysis of supernatants of mouse spleen cells after stimulation with H1sD2 and D2, revealed a qualitatively different cytokine profile from H1sD2 immunized mouse cells (increase in IL10). CD8+ cells were decreased in the lymph node of D2 immunized mice, whereas H1sD2 immunization led to an increase of CD8+ cells in both the lymph node and the spleen.

SIGNIFICANCE

H1sD2 chimera attenuates Der p 2-inherent Th2 response and directs the immune response toward Th1 and Treg phenotype.

The house dust mite allergen Der p 5 binds lipid ligands and stimulates airway epithelial cells through a TLR2-dependent pathway

BACKGROUND

Protein crystallographic studies suggest that the house dust mite (HDM) allergen Der p 5 potentially interacts with hydrophobic ligands. Der p 5, in association with its ligand(s), might therefore trigger innate immune signalling pathways in the airway epithelium and influence the initiation of the HDM-allergic response.

OBJECTIVE

We investigated the lipid binding propensities of recombinant (r)Der p 5 and characterized the signalling pathways triggered by the allergen in airway epithelial cells.

METHODS

rDer p 5 was produced in Pichia pastoris and characterized by mass spectrometry, multi-angle light scattering and circular dichroism. Its interactions with hydrophobic ligands were investigated in fluorescence-based lipid binding assays and in-silico docking simulations. Innate immune signalling pathways triggered by rDer p 5 were investigated in airway epithelial cell activation assays in vitro.

RESULTS

Biophysical analysis showed that rDer p 5 was monomeric and adopted a similar α-helix-rich fold at both physiological and acidic pH. Spectrofluorimetry experiments showed that rDer p 5 is able to selectively bind lipid ligands, but only under mild acidic pH conditions. Computer-based docking simulations identified potential binding sites for these ligands. This allergen, with putatively associated lipid(s), triggered the production of IL-8 in respiratory epithelial cells through a TLR2-, NF-kB- and MAPK-dependent signalling pathway.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite the fact that Der p 5 represents a HDM allergen of intermediate prevalence, our findings regarding its lipid binding and activation of TLR2 indicate that it could participate in the initiation of the HDM-allergic state.

Sensitization to various minor house dust mite allergens is greater in patients with atopic dermatitis than in those with respiratory allergic disease

BACKGROUND

Various allergenic proteins are produced by house dust mites (HDM). However, the allergenicity and clinical implications of these allergens are unknown.

OBJECTIVE

The purpose of this study was to identify allergens in Dermatophagoides farinae and elucidate the sensitization profiles to these in Korean patients suffering from respiratory (allergic rhinitis and/or asthma) and atopic dermatitis symptoms.

METHODS

IgE reactivities in sera from 160 HDM allergy patients were analysed by one- and two-dimensional gel electrophoresis and immunoblotting. IgE-reactive components were identified by liquid chromatography-coupled electrospray ionization-tandem mass spectrometry. Nine recombinant mite allergens (Der f 1, Der f 2, Der f 10, Der f 11, Der f 13, Der f 14, Der f 30, Der f 32 and Der f Alt a 10) were produced, and the IgE reactivity in sera to each was determined by ELISAs.

RESULTS

Der f 1 and Der f 2 were recognized by IgE in serum samples from 88.1% and 78.1% of all patients, respectively. Patients with respiratory allergies were mainly sensitized to these major allergens, whereas patients with atopic dermatitis symptoms showed polysensitization to major and minor allergen components (including Der f 11, Der f 13, Der f 14, Der f 32 and Der f Alt a 10).

CONCLUSIONS

Patients with respiratory allergic disease sensitize to major allergen components of HDM. Those with atopic dermatitis were sensitized to a broader range of minor allergen components of HDM (Der f 11, Der f 13, Der f 14, Der f 32 and Der f Alt a 10).

Cross-sectional study on sensitization to mite and cockroach allergen components in allergy patients in the Central European region

Background

The major sources of allergens in the indoor air include house dust mites, dander derived from domestic animals and rodents, cockroach, and several fungi. Mites are the main cause of allergies in some countries with a warmer climate, but the epidemiological significance of mite and cockroach allergens in Central Europe has not been established yet.

Methods

We assessed sensitization profiles of allergy patients in a Central European region in regard to sensitization to mites and cockroach. We used molecular diagnosis by means of the microarray ISAC, and we investigated 1766 patients with clinical suspicion to an allergic disorder. 1255 of them were positive to at least one allergen component, and this group was subjected to statistical analysis.

Results

The sensitization to at least one mite-specific molecule (Der p 1, 2, Der f 1, 2) was observed relatively frequently in 32.7% of patients. Specific IgE to mite group 2 molecules is almost fully cross-reactive. Group 1 allergens are also cross-reactive, but in some patients, a species-specific response was observed. Relatively high rate of sensitization both to group 1 and 2 allergens in our patients indicates the greater role of co-sensitizations. Isolated sensitizations to molecules derived from glyciphagid mites Lep d 2 and/or Blo t 5 without sensitization to other mite-derived molecules were observed only exceptionally (in 0.6% of cases). True sensitization to at least one cockroach-specific molecule (Bla g 1, 2, 5) was very rare (in 0.6% of cases), and nearly all of them were co-sensitizations with other noncockroach-derived molecules. Sensitization to an inhaled tropomyosin was observed rarely in 2.2% of patients (Der p 10 in 1.9% and Bla g 7 in 1.5%). Co-sensitization of inhaled tropomyosins with the respective mite- or cockroach-specific molecules was observed only in the minority of patients suggesting the different route of sensitization being more frequent.

Conclusions

The majority of patients are co-sensitized to several molecules of the respective allergen source. The knowledge of this molecular spectrum of sensitization is important for optimal diagnosis and treatment in respect to allergen content in mite extracts used for diagnostic and therapeutic purposes. In regard to the sensitization patterns of Central European patients, it is necessary to point out the importance of quantifying at least three major mite components Der f 1, Der p 1 and Der f 2 (or Der p 2).

The Blomia tropicalis allergen Blo t 7 stimulates innate immune signalling pathways through TLR2

BACKGROUND

Although the house dust mite species Blomia tropicalis is a leading cause of allergic diseases in tropical and subtropical regions, the identification and characterization of the allergenic proteins remain incomplete.

OBJECTIVE

We aimed to characterize a recombinant form of Blo t 7 (rBlo t 7) in terms of IgE reactivity, lipid-binding activity and ability to stimulate innate immunity.

METHODS

The mature Blo t 7 cDNA was cloned by PCR methods for the expression of a secreted form of the allergen in P. pastoris. The IgE reactivity to purified rBlo t 7 as well as the potential cross-reactivity with Der p 7 was determined by ELISA. The lipid-binding capacity of rBlo t 7 was assayed using fluorescent lipid probes. The stimulation of TLR2 signalling pathway by rBlo t 7 was examined in cell activation and reporter assays.

RESULTS

The amplified mature Blo t 7 cDNA revealed the presence of a 60 base pair insertion compared with the reference sequence registered in the GenBank database. Multiple protein sequence alignments of group 7 mite allergens confirmed that this longer deduced amino acid sequence was the authentic Blo t 7 polypeptide chain. Analysis of IgE reactivity can classify rBlo t 7 as an intermediate B. tropicalis allergen which displayed weak cross-reactivity with Der p 7. Purified rBlo t 7 was shown to bind selectively the naturally fluorescent lipid probe cis-parinaric (cPNA) with a dissociation constant of 2 μmol/L. The group 7 Blomia allergen stimulated the TLR2-, NF-kB- and MAPK-dependent production of IL-8 and GM-CSF in respiratory epithelial cells.

CONCLUSIONS & CLINICAL RELEVANCE

Through its propensity to transport fatty acids/lipids and to stimulate TLR2 signalling pathways in airway epithelial cells, Blo t 7 can represent a key allergen for the initiation of the B. tropicalis-induced airway inflammation.

Mass spectrometry to complement standardization of house dust mite and other complex allergenic extracts

In the United States, the Center for Biologics Evaluation and Research of the US Food and Drug Administration regulates biologics used for diagnosis and treatment of allergic diseases. The Code of Federal Regulations 21CFR680.3(e) states that when measured, the potency of an allergenic extract is assessed according to its allergenic activity. As of 2016, 19 allergenic extracts are standardized for potency in the United States. While these standardized extracts constitute a minority of those available, they treat the most prevalent allergies (e.g. grass and ragweed pollens, dust mites, and cat) and those that induce life-threatening anaphylaxis (e.g. Hymenoptera venom). Standardization for potency enhances safety and efficacy of immunotherapy by minimizing the risks of variations in allergen dosing when switching from one lot of manufactured extract to another, and by providing an objective measure of stability of each lot of allergenic extract over time. Allergenic extracts that have multiple immunodominant allergenic proteins are standardized with little or no information about compositional differences among extracts. Here, we propose application of mass spectrometry towards measurement of compositional differences among extracts that may affect the efficacy and safety of allergen immunotherapy. In addition, we discuss of house dust mite allergen extracts as a prototypical complex extract that may be standardized by mass spectrometry.

A combined transcriptome and proteome analysis extends the allergome of house dust mite Dermatophagoides species

Background

House dust mites (HDMs) such as Dermatophagoides farinae and D. pteronyssinus represent major causes of perennial allergy. HDM proteomes are currently poorly characterized, with information mostly restricted to allergens. As of today, 33 distinct allergen groups have been identified for these 2 mite species, with groups 1 and 2 established as major allergens. Given the multiplicity of IgE-reactive mite proteins, potential additional allergens have likely been overlooked.

Objective

To perform a comprehensive characterization of the transcriptomes, proteomes and allergomes of D. farinae and D. pteronyssinus in order to identify novel allergens.

Methods

Transcriptomes were analyzed by RNA sequencing and de novo assembly. Comprehensive mass spectrometry-based analyses proteomes were combined with two-dimensional IgE reactivity profiling.

Results

Transcripts from D. farinae and D. pteronyssinus were assembled, translated into protein sequences and used to populate derived sequence databases in order to inform immunoproteomic analyses. A total of 527 and 157 proteins were identified by bottom-up MS analyses in aqueous extracts from purified HDM bodies and fecal pellets, respectively. Based on high sequence similarities (>71% identity), we also identified 2 partial and 11 complete putative sequences of currently undisclosed D. pteronyssinus counterparts of D. farinae registered allergens. Immunoprofiling on 2D-gels revealed the presence of unknown 23 kDa IgE reactive proteins in both species. Following expression of non-glycosylated recombinant forms of these molecules, we confirm that these new allergens react with serum IgEs from 42% (8/19) of HDM-allergic individuals.

Conclusions

Using combined transcriptome and immunoproteome approaches, we provide a comprehensive characterization of D. farinae and D. pteronyssinus allergomes. We expanded the known allergen repertoire for D. pteronyssinus and identified two novel HDM allergens, now officially referred by the International Union of Immunological Societies (IUIS) Nomenclature Subcommittee as Der f 36 and Der p 36.