Atopic Dermatitis and Sensitisation to Molecular Components of Alternaria, Cladosporium, Penicillium, Aspergillus, and Malassezia-Results of Allergy Explorer ALEX 2

Bayesian analysis suggests independent development of sensitization to different fungal allergens

Background

Fungi are known for their ability to cause allergies, but data on individual sensitization to them are insufficient. The purpose of the study was to carry out a comprehensive analysis of the fungal allergens' sensitization profile in the Ukrainian population and to determine both population and individual sensitivity to these allergens.

Methods

We utilized a set of ALEX allergy test data from 20,033 inhabitants of 17 regions of Ukraine from 1 to 89 years conducted in 2020-2022. A complex of programs in the Python language was developed and Bayesian network analysis was applied to determine the sensitivity combinations in individual patients to various fungal components.

Results

Sensitivity to Alt a 1 dominated and was observed in 79.39% of patients, and 62.17% of them were sensitive solely to Alt a 1. Exclusive sensitivity to Mala s 6 was second in individual patient profiles with a frequency of 4.06%. Combined sensitivity to Alt a 1 - Asp f 3 was third with a share of 3.28%. Pen ch and Cla h extracts stimulated the production of the lowest median sIgE levels. The highest median sIgE levels were for Alt a 1, Mala s 11 and Asp f 6, respectively. Median sIgE levels increased in adults compared to children for all components of Aspergillus fumigatus, as well as for Mala s 5 and Mala s 11. In the rest of the cases, they decreased in adults compared to children. The sensitization rates to fungi in general and specifically to Alternaria were lower in the western parts of Ukraine, especially in the Carpathian region, situated within the Broad-leaved Forest zone. The results of Bayesian modeling revealed that in the case of Alt a 1, the simultaneous absence of sensitivity to Cla h 8, Mala s 11, Mala s 5 and Mala s 6 molecules could condition the presence of sensitization to the major Alternaria allergen with a probability of 92.42%. In all other cases, there was a high probability of absence of sensitivity to particular allergen against the background of absence of sensitivity to other ones, which may indicate the independent development of sensitization to different fungal allergens.

Conclusions

Sensitivity to Alt a 1 dominated in the studied population with a lower rate in the western regions. The highest median sIgE levels were induced by Alt a 1, Mala s 11 and Asp f 6. Bayesian Analysis suggest a high probability of the independent development of sensitization to different fungal allergens. The idea that sensitization to one allergen may be protective against sensitization to another one(s) requires further clinical study.

Fungal allergen sensitization: Prevalence, risk factors, and geographic variation in the United States

BACKGROUND

Many fungal species are associated with the pathogenesis of allergic disease, yet most epidemiologic studies on IgE-mediated fungal sensitization have only included a few species.

OBJECTIVE

We investigated fungal allergen sensitization prevalence, risk factors, and geographic variation in the United States.

METHODS

From 2014 to 2019, a total of 7,912,504 serum-specific IgE (sIgE) test results for 17 fungal species were measured in 1,651,203 patients aged 0-85 years by a US-wide clinical laboratory. Fungal sensitization prevalence, patterns, and relationship with demographic characteristics, clinical diagnoses, and geographic regions were analyzed.

RESULTS

Twenty-two percent of patients were positive (sIgE > 0.10 kUA/L) to at least 1 fungal allergen; 13.7% were positive to >2 fungal allergens. Fungal species-specific positivity rates ranged 7.4-18.6% and were highest for Candida albicans (18.6%), Alternaria alternata (16.6%), Stemphylium herbarum (14.9%), and Aspergillus fumigatus (14.2%). Other fungi that were frequently tested had relatively low positivity rates (eg, Cladosporium herbarum 11.1%, Penicillium chrysogenum 10.7%). Independent risk factors for test positivity for all fungal species included male sex, teen age (highest in those aged 10-19 years), atopic dermatitis, and asthma. Fungal sensitization was generally higher in urban areas and ecoregions composed predominantly of grasslands and prairies compared to woodlands and forest, although there was greater variation in sensitization risk to different fungi in different ecoregions.

CONCLUSION

Independent risk factors for fungal sensitization include male sex, teen ages, atopic dermatitis, asthma, and ecoregion.

The Role of the Cutaneous Mycobiome in Atopic Dermatitis

Atopic dermatitis is a chronic inflammatory skin disorder characterized by eczematous lesions, itch, and a significant deterioration in the quality of life. Recently, microbiome dysbiosis has been implicated in the pathogenesis of atopic dermatitis. Changes in the fungal microbiome (also termed mycobiome) appear to be an important factor influencing the clinical picture of this entity. This review summarizes the available insights into the role of the cutaneous mycobiome in atopic dermatitis and the new research possibilities in this field. The prevalence and characteristics of key fungal species, the most important pathogenesis pathways, as well as classic and emerging therapies of fungal dysbiosis and infections complicating atopic dermatitis, are presented.

Four clinical phenotypes of cow’s milk protein allergy based on dairy product specific IgE antibody types in North China

Background

Cow’s milk protein allergy (CMPA) is a common allergy. Immunoglobulin E (IgE)-mediated cow’s milk allergy is associated with a high mortality risk and poor prognosis. The study aims to investigate whether there are different clinically CMPA phenotypes in China and to explore the association between CMPA phenotypes and specific IgE (sIgE) antibodies against different dairy products.

Methods

Serum sIgE against different animal milk and cow’s milk products and different milk components was measured by an allergen array. Four CMPA classifications were identified by the presence of serum sIgE: boiled milk-positive, yogurt-positive, buttermilk-positive, and raw milk-positive.

Results

Among the 234 participants included in the study, 9 were boiled milk sIgE-positive, 50 were yogurt sIgE-positive, 17 were buttermilk sIgE-positive, and 158 were only raw milk sIgE-positive. The boiled milk-positive group had the highest levels of raw milk sIgE and casein sIgE antibodies, followed sequentially by the yogurt-positive, buttermilk-positive, and raw milk-positive groups. The boiled milk group observed the highest levels of sIgE against raw milk, casein, α-lactalbumin, and β-lactoglobulin. These levels differed significantly from those in the other three groups. Allergic symptoms were distributed differently among the four study groups. The percentages of allergic patients with gastrointestinal tract symptoms in the above mentioned four groups ranged from high to low, and the percentages of patients with skin symptoms in the four groups ranged from low to high, respectively.

Conclusion

Based on dairy product sIgE antibody levels associated with different milk components and various clinical allergic symptom tendencies, we could distinguish four CMPA phenotypes.

IgE reactivity patterns in Asian and central European cockroach-sensitized patients reveal differences in primary sensitizing allergen sources

Background

The prevalence of cockroach (CR) sensitization and its relevance as a trigger of allergy symptoms differs greatly in different geographic areas.

Objective

This study aimed to compare molecular IgE reactivity profiles in CR-sensitized patients with perennial allergy symptoms from Hong Kong (HK) and Austria and identify the main primary sensitizers.

Methods

IgE sensitization was assessed by skin prick test and/or IgE reactivity with CR extract. Molecular IgE reactivity profiles were analyzed via multiplex assay for sensitization to allergens and extracts from CR, house dust mite (HDM), shellfish, and 3 additional insect species.

Results

HDM was the main primary sensitizer in both cohorts. In the HK group, genuine sensitization to CR was found in 45%, but none of the patients in the Austrian cohort was truly sensitized to that allergen source. Most patients from HK were cross-sensitized to other insects and/or shellfish, presumably by broad reactivity to tropomyosin and arginine kinase. About half of Austrian subjects lacked IgE to these pan-allergens, indicating co- but not cross-sensitization to insects and/or shellfish. Regarding IgE recognition frequencies, arginine kinases (64% HK, 10% Austria) and tropomyosins (42% HK, 15% Austria) were most frequently recognized; Bla g 4 (lipocalin) was detected in HK patients only (42%). Tropomyosin (Per a 7) was significantly more frequently recognized in patients with asthma. Sera from HDM-sensitized subjects from HK showed a higher proportion of sensitization to minor mite allergens.

Conclusion

Molecular profiling identified differences between CR-sensitized allergic patients from HK and Austria in terms of primary sensitizers and molecular IgE reactivity patterns. Tropomyosin from American cockroach (Per a 7) was shown to be significantly associated with asthma symptoms and might be suitable as biomarker for more severe respiratory allergy symptoms.

Characterization of Distinct Microbiota Associated with Scalp Dermatitis in Patients with Atopic Dermatitis

Recent studies have focused on the role of skin microbiota in the pathogenesis of atopic dermatitis (AD). Among the various clinical phenotypes of AD, scalp dermatitis is a commonly observed clinical feature of AD. However, little is known about the pathogenesis of scalp dermatitis in AD. Hence, the aim of this study was to identify the distinct microbiota associated with scalp dermatitis in patients with AD. Using scalp swab samples from 10 patients with AD and 10 healthy controls, this study characterized the scalp microbiota in patients with AD via V3–V4 regions of the 16S rRNA gene sequencing for bacterial identification, and ITS2 gene sequencing for fungal identification. Among bacterial genera, Staphylococcus was the most abundant in AD than in healthy controls, whereas Cutibacterium was the most abundant species in the healthy controls. The most predominant scalp fungal microbiota was Malassezia both in AD and healthy controls, while a higher diversity of non-Malassezia fungi was observed in AD than in healthy controls. The study findings indicate the dysbiosis of scalp microbiota in AD and highlight the potential biomarker role of specific microbiota in AD on the scalp dermatitis.

Aspergillus fumigatus-Host Interactions Mediating Airway Wall Remodelling in Asthma

Asthma is a chronic heterogeneous respiratory condition that is mainly associated with sensitivity to airborne agents such as pollen, dust mite products and fungi. Key pathological features include increased airway inflammation and airway wall remodelling. In particular, goblet cell hyperplasia, combined with excess mucus secretion, impairs clearance of the inhaled foreign material. Furthermore, structural changes such as subepithelial fibrosis and increased smooth muscle hypertrophy collectively contribute to deteriorating airway function and possibility of exacerbations. Current pharmacological therapies focused on airway wall remodelling are limited, and as such, are an area of unmet clinical need. Sensitisation to the fungus, Aspergillus fumigatus, is associated with enhanced asthma severity, bronchiectasis, and hospitalisation. How Aspergillus fumigatus may drive airway structural changes is unclear, although recent evidence points to a central role of the airway epithelium. This review provides an overview of the airway pathology in patients with asthma and fungal sensitisation, summarises proposed airway epithelial cell-fungal interactions and discusses the initiation of a tissue remodelling response. Related findings from in vivo animal models are included given the limited analysis of airway pathology in patients. Lastly, an important role for Aspergillus fumigatus-derived proteases in triggering a cascade of damage-repair events through upregulation of airway epithelial-derived factors is proposed.

Precision medicine in the allergy clinic: the application of component resolved diagnosis

INTRODUCTION

A precise diagnosis is key for the optimal management of allergic diseases and asthma. In vivo or in vitro diagnostic methods that use allergen extracts often fail to identify the molecules eliciting the allergic reactions.

AREAS COVERED

Component-resolved diagnosis (CRD) has solved most of the limitations of extract-based diagnostic procedures and is currently valuable tool for the precision diagnosis in the allergy clinic, for venom and food allergy, asthma, allergic rhinitis, and atopic dermatitis. Its implementation in daily practice facilitates: a) the distinction between genuine multiple sensitizations and cross-reactive sensitization in polysensitized patients; b) the prediction of a severe, systemic reaction in food or insect venom allergy; c) the optimal selection of allergen immunotherapy based on the patient sensitization profile. This paper describes its main advantages and disadvantages, cost-effectiveness and future perspectives.

EXPERT OPINION

The diagnostic strategy based on CRD is part of the new concept of precision immunology, which aims to improve the management of allergic diseases.

MalaSelect: A Selective Culture Medium for Malassezia Species

Malassezia species are fastidious and slow-growing yeasts in which isolation from polymicrobial samples is hampered by fast-growing microorganisms. Malassezia selective culture media are needed. Although cycloheximide is often used, some fungi, including the chief human commensal Candida albicans, are resistant to this compound. This study aimed to test whether the macrolide rapamycin could be used in combination with cycloheximide to develop a Malassezia-selective culture medium. Rapamycin susceptibility testing was performed via microdilution assays in modified Dixon against two M. furfur and five Candida spp. The MIC was the lowest concentration that reduced growth by a minimum of 90%. Rapamycin ± cycloheximide 500 mg/L was also added to FastFung solid, and yeast suspensions were inoculated and incubated for 72 h. Rapamycin MICs for Candida spp. ranged from 0.5 to 2 mg/L, except for C. krusei, for which the MIC was >32 mg/L. M. furfur stains were rapamycin-resistant. Rapamycin and cycloheximide supplementation of the FastFung medium effectively inhibited the growth of non-Malassezia yeast, including cycloheximide-resistant C. albicans and C. tropicalis. Based on our findings, this “MalaSelect” medium should be further evaluated on polymicrobial samples for Malassezia isolation and culture.

A qualitative and quantitative comparison of IgE antibody profiles with two multiplex platforms for component-resolved diagnostics in allergic patients

BACKGROUND

Clinically complex phenotypes require more and more sophisticated and comprehensive diagnostic approaches, able to discriminate genuine sensitizations from cross-reactivity. Interpretative complexity of multiplex diagnostic arrays has somewhat limited their diffusion. This study compares two currently available methods, namely ISAC^® test and ALEX2^® test.

METHODS

In total, 140 allergic individuals, with a history of atopic dermatitis, adverse food reactions, allergic rhinitis and/or bronchial asthma were studied by Allergy Explorer-ALEX2^® macroarray and ImmunoCAP ISAC112^® . Lin's concordance correlation coefficient, intraclass correlation coefficient and Bland-Altman plots were used to verify the agreement between continuous values. Cohen's kappa coefficient (k) was assessed for the molecules available in both tests. The degree of relationship was analysed using Spearman's correlation (quantitative variables) and Pearson's χ² or Fisher's exact test (categorical variables).

RESULTS

A substantial agreement (κ = 0.795) was observed between the two methods with 94,3% concordant results when results were dichotomized as negative or positive, but if double-negative results were discarded, the agreement dropped to 71%. Conversely, little or no concordance was observed comparing raw data. Considering the 102 molecules shared by both systems, 28/102 (27%) showed an almost perfect agreement (k > 0.81), and concordance was good (k > 0.61) in a further 32 (31%) cases. A perfect to substantial agreement was observed by comparing species-specific aeroallergens. Heterogeneous results emerged comparing panallergens (co-recognition ranging from 30% for tropomyosin/serum albumins to 70% for PR-10/profilin). The correlation among LTP, profilin and PR-10 assayed with ISAC^® was better than ALEX2^® , but the latter identified more positive cases due to the wider number of molecules available. The CCD blocker provided by ALEX^® test abolishes the carbohydrate determinants signal in 60% of the 33 cases reactive to MUXF3 on the ISAC^® test.

CONCLUSION

Despite the excellent concordance of the species-specific markers, the analysis of the panallergens provided in both methods suggests a better performance of the ISAC^® test on those components, while the ALEX2^® test, which includes a larger number of allergens, allowing a broader molecular detection.