Asthma and Fungus: Role in Allergic Bronchopulmonary Aspergillosis (ABPA) and Other Conditions

The Fungal Microbiome of the Upper Airway Is Associated With Future Loss of Asthma Control and Exacerbation Among Children With Asthma

BACKGROUND

Accumulating evidence suggests that the upper airway bacterial microbiota is implicated in asthma inception, severity, and exacerbation. Unlike bacterial microbiota, the role of the upper airway fungal microbiome (mycobiome) in asthma control is poorly understood.

RESEARCH QUESTION

What are the upper airway fungal colonization patterns among children with asthma and their relationship with subsequent loss of asthma control and exacerbation of asthma?

STUDY DESIGN AND METHODS

The study was coupled with the Step Up Yellow Zone Inhaled Corticosteroids to Prevent Exacerbations (ClinicalTrials.gov Identifier: NCT02066129) clinical trial. The upper airway mycobiome was investigated using Internal transcribed spacer 1 (ITS1) sequencing of nasal blow samples collected from children with asthma when asthma was well controlled (baseline, n = 194) and during early signs of loss of asthma control (yellow zone [YZ], n = 107).

RESULTS

At baseline, 499 fungal genera were detected in the upper airway samples, with two commensal fungal species, Malassezia globosa and Malassezia restricta, being most dominant. The relative abundance of Malassezia species varies by age, BMI, and race. Higher relative abundance of M globosa at baseline was associated with lower risk of future YZ episodes (P = .038) and longer time to development of first YZ episode (P = .022). Higher relative abundance of M globosa at YZ episode was associated with lower risk of progression from YZ episode to severe asthma exacerbation (P = .04). The upper airway mycobiome underwent significant changes from baseline to YZ episode, and increased fungal diversity was correlated highly with increased bacterial diversity (ρ = 0.41).

INTERPRETATION

The upper airway commensal mycobiome is associated with future asthma control. This work highlights the importance of the mycobiota in asthma control and may contribute to the development of fungi-based markers to predict asthma exacerbation.

Respiratory comorbidities in severe asthma: focus on the pediatric age

INTRODUCTION

Asthma comorbidities are a frequent cause of adverse outcomes, such as poor asthma control, frequent asthma attacks, reduced quality of life, and higher healthcare costs. Comorbidities are well-known treatable traits whose proper management can help achieve optimal asthma control. Although multimorbidity is frequent among asthmatics, comorbidities are still a potential cause of misdiagnosis and under or over treatments, and little is known about their impact on severe pediatric asthma.

AREAS COVERED

We provided a comprehensive, 5-year updated review focusing on the main respiratory comorbidities in severe asthma, particularly in epidemiology, pathogenesis, and current and future therapies.

EXPERT OPINION

Respiratory comorbidities have unique characteristics in childhood. Their management must be multidisciplinary, age-specific, and integrated. Further longitudinal studies are needed to understand better the mutual interrelation and synergistic effect between asthma and its respiratory comorbidities, the identification of common, treatable risk factors leading to potential asthma prevention, the effectiveness of actual and future target-therapies, and the correlation between long-lasting respiratory comorbidities and poor lung function trajectories.

The Role of Comorbidities in Difficult-to-Control Asthma in Adults and Children

Assessment of asthma comorbidities, conditions that adversely affect the pathobiology of asthma or impair its response to therapies, is a fundamental step in the evaluation and management of patients with difficult-to-treat asthma. Identifying and effectively treating asthma comorbidities, such as obesity, obstructive sleep apnea, and chronic sinusitis with nasal polyps, may improve asthma control and reduce exacerbations. In addition, identifying comorbid T2 inflammatory conditions may help guide optimal selection of biologic therapies. Here, we describe common comorbid conditions found in adult and pediatric difficult-to-control asthma, discuss evidence for the association with asthma morbidity and treatment benefit, and provide information on how and when to assess comorbidities.

Do not forget asthma comorbidities in pediatric severe asthma!

Asthma is the most common chronic respiratory disease in childhood. The long-term goals in managing asthma aim to control symptoms and prevent exacerbations, as well as to reduce side effects of therapy and mortality disease-related. Most of patients have mild to moderate asthma and respond well to standard therapies. However, a minor proportion of children with asthma has severe disease that remains uncontrolled despite optimal adherence to prescribed therapy and treatment of contributory factors, including trigger exposures and comorbidities, which can mimic or worsen asthma and contribute to exacerbations and poor quality of life. Evaluation of comorbidities is fundamental to optimize the management of the disease in a subgroup of patients with poor responder asthma. The overall aim of this article is to describe characteristics of main pediatric severe asthma comorbidities reported in literature, giving clinicians tools to recognize and manage properly these conditions.

Striking Back against Fungal Infections: The Utilization of Nanosystems for Antifungal Strategies

Fungal infections have become a major health concern, given that invasive infections by Candida, Cryptococcus, and Aspergillus species have led to millions of mortalities. Conventional antifungal drugs including polyenes, echinocandins, azoles, allylamins, and antimetabolites have been used for decades, but their limitations include off-target toxicity, drug-resistance, poor water solubility, low bioavailability, and weak tissue penetration, which cannot be ignored. These drawbacks have led to the emergence of novel antifungal therapies. In this review, we discuss the nanosystems that are currently utilized for drug delivery and the application of antifungal therapies.

Comprehensive transcriptome analysis of peripheral blood unravels key lncRNAs implicated in ABPA and asthma

Allergic bronchopulmonary aspergillosis (ABPA) is a complex hypersensitivity lung disease caused by a fungus known as Aspergillus fumigatus. It complicates and aggravates asthma. Despite their potential associations, the underlying mechanisms of asthma developing into ABPA remain obscure. Here we performed an integrative transcriptome analysis based on three types of human peripheral blood, which derived from ABPA patients, asthmatic patients and health controls, aiming to identify crucial lncRNAs implicated in ABPA and asthma. Initially, a high-confidence dataset of lncRNAs was identified using a stringent filtering pipeline. A comparative mutational analysis revealed no significant difference among these samples. Differential expression analysis disclosed several immune-related mRNAs and lncRNAs differentially expressed in ABPA and asthma. For each disease, three sub-networks were established using differential network analysis. Many key lncRNAs implicated in ABPA and asthma were identified, respectively, i.e., AL139423.1-201, AC106028.4-201, HNRNPUL1-210, PUF60-218 and SREBF1-208. Our analysis indicated that these lncRNAs exhibits in the loss-of-function networks, and the expression of which were repressed in the occurrences of both diseases, implying their important roles in the immune-related processes in response to the occurrence of both diseases. Above all, our analysis proposed a new point of view to explore the relationship between ABPA and asthma, which might provide new clues to unveil the pathogenic mechanisms for both diseases.

Cross-reactive antibodies against dust mite-derived enolase induce neutrophilic airway inflammation

BACKGROUND AND AIMS

Neutrophilic inflammation is a hallmark of some specific asthma phenotypes; its aetiology is not yet fully understood. House dust mite (HDM) is the most common factor in the pathogenesis of airway inflammation. This study aims to elucidate the role of cross-antibodies against HDM-derived factors in the development of neutrophilic inflammation in the airway.

METHODS

Blood samples were collected from asthma patients with chronic neutrophilic asthma for analysis of HDM-specific cross-reactive antibodies. The role of an antibody against HDM-derived enolase (EnoAb) in the impairment of airway epithelial barrier function and induction of airway inflammation was assessed in a cell culture model and an animal model.

RESULTS

High similarity (72%) of the enolase gene sequences was identified between HDM and human. Serum EnoAb was detected in patients with chronic neutrophilic asthma. The EnoAb bound to airway epithelial cells to form complexes with enolase, which activated complement, impaired airway epithelial barrier functions and induced neutrophilic inflammation in the airway tissues.

CONCLUSIONS

HDM-derived enolase can induce specific cross-antibodies in humans, which induce neutrophilic inflammation in the airway.

Diagnosis of allergic bronchopulmonary aspergillosis in patients with persistent allergic asthma using three different diagnostic algorithms

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) has been reported in various degrees among patients with persistent allergic asthma (PAA). Currently, there is no gold standard approach for diagnosis of ABPA.

OBJECTIVES

In the current study, we aimed the evaluation of three different mainly used algorithms as Rosenberg & Patterson (A), ISHAM Working Group (B) and Greenberger (C) for diagnosis of ABPA in 200 patients with underlying PAA.

METHODS

All patients were evaluated using Aspergillus skin prick test (SPTAf), Aspergillus-specific IgE (sIgEAf) and IgG (sIgGAf), total IgE (tIgE), pulmonary function tests, radiological findings and peripheral blood eosinophil count. The prevalence rate of ABPA in PAA patients was estimated by three diagnostic criteria. We used Latent Class Analysis for the evaluation of different diagnostic parameters in different applied ABPA diagnostic algorithms.

RESULTS

Aspergillus sensitisation was observed in 30 (15.0%) patients. According to algorithms A, B and C, nine (4.5%), six (3.0%) and 11 (5.5%) of patients were diagnosed with ABPA, respectively. The sensitivity and specificity of criteria B and C were (55.6% and 99.5%) and (100.0% and 98.9%) respectively. sIgEAf and sIgGAf showed the high significant sensitivity. The performance of algorithm A, in terms of sensitivity and specificity, was somewhat better than algorithm B.

CONCLUSION

Our study demonstrated that the sensitivity of different diagnostic algorithms could change the prevalence rate of ABPA. We also found that all of three criteria resulted an adequate specificity for ABPA diagnosis. A consensus patterns combining elements of all three criteria may warrant a better diagnostic algorithm.

Need to re-look cut-off of Aspergillus-specific IgE levels in children with ABPA

The cut-offs for total and specific IgE used for diagnosing ABPA in children have been adopted from adult literature and have not been validated in the paediatric population. To establish the ideal cut-offs of total IgE and Aspergillus-specific IgE for the diagnosis of ABPA in children. This study was a prospective observational case-control study, conducted in a tertiary care hospital in North India, enrolling 140 children with partly controlled and uncontrolled asthma. Seventy children had ABPA based on the Rosenberg-Patterson Criteria (Cases) whereas 70 children were without ABPA (Controls). All children were subjected to clinical examination and investigations such as absolute eosinophil count, total IgE, Aspergillus-specific IgE, Aspergillus skin prick test and radiological tests. ROC curve analysis was done to determine the ideal cut-offs of total and specific IgE to diagnose ABPA. The ROC curve analysis determined 1204IU/L as the cut-off value of total IgE with a sensitivity of 79.7% (95%CI 68.31% to 88.44%) and specificity of 53.1% (95%CI 40.23 to 65.7). The ROC analysis of specific IgE levels of children with ABPA determined the cut-off value of 0.49 KAU/L with a sensitivity of 94.03% (95%CI 85.41 to 98.35) and specificity of 88.89% (95%CI 75.94% to 96.29%). We propose that the cut-offs of total and specific IgE need to be relooked in the paediatric population. Cut-offs of total IgE as 1204 IU/L and for Aspergillus-specific IgE as 0.49KAU/L seem appropriate. Large multicentric studies should be conducted to determine the ideal values for diagnosing paediatric ABPA.

Prevalence of specific immunoglobulin E and G against Aspergillus fumigatus in patients with asthma

Background and Purpose

Aspergillus fumigatus as a ubiquitous fungus can be found in the respiratory tract of the asthmatic and healthy people. The inhalation of Aspergillus spores leads to an immune response in individuals with asthma and results in the aggravation of the clinical symptoms. The present study aimed to investigate the prevalence of specific immunoglobulin E and G (IgE and IgG) against A.fumigatus in asthmatic patients.

Materials and Methods

This study was conducted on 200 consecutive patients with moderate to severe asthma referring to Masih Daneshvari hospital Tehran, Iran, from January 2016 to February 2018. Skin prick test (SPT) was performed in all subjects with Aspergillus allergens. Moreover, all patients underwent specific IgE testing for Aspergillus using Hycor method. Enzyme immune assay was applied to measure total IgE and Aspergillus-specific IgG.

Results

According to the results, the mean age of the patients was 45.8 years (age range: 18-78 years). The mean levels of total IgE and Aspergillus specific IgE in asthmatic patients were obtained as 316.3 (range: 6-1300 IU/ml) and 1.5 (range: 0.1-61.3 IU/ml), respectively. Out of 200 patients, 27 (13.5%), 65 (32.5%), 22 (11.0%), and 86 (43.0%) cases had positive Aspergillus SPT, total IgE of > 417 IU/ml, Aspergillus -specific IgE, and IgG, respectively. The level of these variables in patients with severe asthma were 16 (16.5%), 36 (37.1%), 15 (15.5%), and 46 (47.4%), respectively.

Conclusion

As the findings indicated, reactivity to Aspergillus is a remarkable phenomenon in asthmatic patients. It is also emphasised that the climatic condition may affect the positive rate of hypersensitivity to Aspergillus.

Does allergy explain why some children have severe asthma?

Asthma is a common disease in childhood with a minority of affected children having severe therapy-resistant asthma (STRA). Children with STRA can be differentiated from those with mild-moderate disease by greater allergic sensitization, increased eosinophilic airway inflammation, increased airway remodelling and reduced corticosteroid responsiveness. The aetiology of STRA in children is multifactorial but allergy seems to play a key role. Many children with asthma have coexisting allergic disease, and severe rhinitis seems to be an important driver of STRA in children. Allergies to foods, moulds, pollen and pets have also been associated with severe asthma exacerbations. Identifying allergens that are driving asthma symptoms in children with STRA may provide additional strategies for improving their disease control. Avoidance strategies may be possible. Additional monoclonal antibody therapy with Omalizumab or Mepolizumab may be helpful in children with clinically important polysensitization.