Evaluation of mold exposure in cystic fibrosis patients' dwellings and allergic bronchopulmonary risk

Climate change and children's respiratory health

Climate change has significant consequences for children's respiratory health. Rising temperatures and extreme weather events increase children's exposure to allergens, mould, and air pollutants. Children are particularly vulnerable to these airborne particles due to their higher ventilation per unit of body weight, more frequent mouth breathing, and outdoor activities. Children with asthma and cystic fibrosis are at particularly high risk, with increased risks of exacerbation, but the effects of climate change could also be observed in the general population, with a risk of impaired lung development and growth. Mitigation measures, including reducing greenhouse gas emissions by healthcare professionals and healthcare systems, and adaptation measures, such as limiting outdoor activities during pollution peaks, are essential to preserve children's respiratory health. The mobilisation of society as a whole, including paediatricians, is crucial to limit the impact of climate change on children's respiratory health.

Fungal Colonization of the Airways of Patients with Cystic Fibrosis: the Role of the Environmental Reservoirs

Filamentous fungi frequently colonize the airways of patients with cystic fibrosis and may cause severe diseases, such as the allergic bronchopulmonary aspergillosis. The most common filamentous fungi capable to chronically colonize the respiratory tract of the patients are Aspergillus fumigatus and Scedosporium species. Defining the treatment strategy may be challenging, the number of available drugs being limited and some of the causative agents being multiresistant microorganisms. The knowledge of the fungal niches in the outdoor and indoor environment is needed for understanding the origin of the contamination of the patients. In light of the abundance of some of the causative molds in compost, agricultural and flower fields, occupational activities related to such environments should be discouraged for patients with cystic fibrosis (CF). In addition, the microbiological monitoring of their indoor environment, including analysis of air and dust on surfaces, is essential to propose preventive measures aiming to reduce the exposure to environmental molds. Nevertheless, some specific niches were also identified in the indoor environment, in relation with humidity which favors the growth of thermotolerant molds. Potted plants were reported as indoor reservoirs for Scedosporium species. Likewise, Exophiala dermatitidis may be spread in the kitchen via dishwashers. However, genotype studies are still required to establish the link between dishwashers and colonization of the airways of CF patients by this black yeast. Moreover, as nothing is known regarding the other filamentous fungi associated with CF, further studies should be conducted to identify other potential specific niches in the habitat.

Aiming to Improve Equity in Pulmonary Health: Cystic Fibrosis

This review summarizes the evidence of health disparities in cystic fibrosis (CF), an autosomal recessive genetic disorder with substantial variation in disease progression and outcomes. We review disparities by race, ethnicity, socioeconomic status, geographic location, gender identity, or sexual orientation documented in the literature. We outline the mechanisms that generate and perpetuate such disparities across levels and domains of influence and assess the implications of this evidence. We then recommend strategies for improving equity in CF outcomes, drawing on recommendations for the general population and considering approaches specific to people living with CF.

Socioeconomic determinants of respiratory health in patients with cystic fibrosis: implications for treatment strategies

INTRODUCTION

Great variation exists in the progression and outcomes of cystic fibrosis (CF) lung disease, due to both genetic and environmental influences. Social determinants mediate environmental exposures and treatment success; people with CF from socioeconomically disadvantaged backgrounds have worse health and die younger than those in more advantaged positions.

AREAS COVERED

This paper reviews the literature on the mechanisms that are responsible for generating and sustaining disparities in CF health, and the ways by which social determinants translate into health advantages or disadvantages in people with CF. The authors make recommendations for addressing social risk factors in CF clinical practice.

EXPERT OPINION

Socioeconomic factors are not dichotomous and their impact is felt at every step of the social ladder. CF care programs need to adopt a systematic protocol to screen for health-related social risk factors, and then connect patients to available resources to meet individual needs. Considerations such as daycare, schooling options, living and working conditions, and opportunities for physical exercise and recreation as well as promotion of self-efficacy are often overlooked. In addition, advocacy for changes in public policies on health insurance, environmental regulations, social welfare, and education would all help address the root causes of CF health inequities.

[Allergic Broncho-Pulmonary Aspergillosis (ABPA) in cystic fibrosis: Mechanisms, diagnosis and therapeutic options]

INTRODUCTION

Fungal aspergillosis colonization and allergic bronchopulmonary aspergillosis (ABPA) can have a strong impact on the prognosis in cystic fibrosis (CF). We conducted round table discussions involving French experts from pediatric and adult centers caring for patients with CF, microbiologists, radiologists and pharmacists. The aim was to explore the current state of knowledge on: the pathophysiological mechanisms of Aspergillus and other micromycetes infections in CF (such as Scedosporium sp.), and on the clinico-biological diagnosis of ABPA. In perspective, the experts explored the role of imaging in the diagnosis of APBA, specifically CT and MRI; as well as the role of bronchoscopy in the management. We also reviewed the therapeutic management, including different corticosteroid regimens, antifungals and anti-IgE antibodies.

CONCLUSION

The diagnosis of ABPA in CF should be based on more standardized biological assays and imaging to optimize treatment and follow-up.

Comparative Analysis of Clinical Parameters and Sputum Biomarkers in Establishing the Relevance of Filamentous Fungi in Cystic Fibrosis

Background

The relationship between fungal culture (FC) positivity and airway inflammation in CF is largely unknown. Identifying the clinical significance of filamentous fungi in CF using both clinical parameters and biomarkers may change our antimicrobial therapeutic strategies.

Objectives

To investigate the clinical characteristics and airway biomarker profile in relation to the detection of filamentous fungi in respiratory samples obtained from CF patients.

Methods

A prospective cohort study over 24 months, including children and adults with CF. Participants provided sputum and/or bronchoalveolar lavage samples, which underwent processing for bacterial and fungal culture, leukocyte differential cell count and biomarker analysis for neutrophil elastase (NE), interleukin-8 (IL-8), galactomannan and tumor necrosis factor receptor type 2 (TNF-R2). We performed FC using neat sputum plugs, an approach shown to be more sensitive compared to routine laboratory testing.

Results

Sixty-one patients provided 76 respiratory samples (72 sputum and 4 BAL). Median age was 17 years (range 6 months-59 years). FC positivity was noted in 49% of the cohort. FC positivity was greater during pulmonary exacerbation compared to the stable state (67 versus 50%). Participants aged 5-30 years had a lower FEV1 within the FC positive group. A significant association between FC positivity and non-tuberculosis mycobacterial (NTM) culture was observed on non-parametric testing (p = 0.022) and regression analysis (p = 0.007). Exposure to indoor mold was a predictor for FC positivity (p = 0.047). There was a trend towards increased lung clearance index (LCI), bronchiectasis and intravenous antibiotic use in the FC positive group. There was no significant difference in biomarkers between FC positive and negative patients.

Conclusion

Aspergillus. fumigatus is the commonest filamentous fungi cultured from CF airways. We found no difference in the airway biomarker profile between FC positive and negative patients. The role of galactomannan and TNFR2 as fungal specific biomarkers in CF remains uncertain. FC positivity is associated with a lower FEV₁ in younger patients, a lower LCI, NTM positivity, bronchiectasis, and intravenous antibiotic exposure. Larger trials are needed to determine the role of galactomannan and TNF-R2 as potential fungal biomarkers in CF.

Disruption of Aspergillus fumigatus biofilm by Streptococcus pneumoniae: Mycelial fragmentation by hydrogen peroxide

Biofilm is a complex structure consisting of microorganisms such as bacteria, fungi and an extracellular matrix (ECM). Biofilms are involved in most microbial infections and show persistent resistance to antibiotic treatment and immune response. Both Aspergillus fumigatus and Streptococcus pneumoniae are colonizers that can form biofilms in the respiratory tract. These pathogens have been simultaneously isolated from the same patient, but their interaction is poorly understood. We observed morphological changes in single- and mixed-species biofilms prepared for confocal laser scanning microscopy and scanning electron microscopy (SEM). Pneumococci suppressed the development of a fungal biofilm, and it even disrupted a preformed fungal biofilm. When a preformed fungal biofilm was treated with pneumococci, the mycelial network was fragmented, and only bacteria could develop. SEM revealed that the fragmented mycelium was further disrupted into fine filaments as treatment time progressed, and that the ECM of the preformed fungal biofilm had disappeared. The pneumococcal culture supernatant contained mycelial fragmentation activity that was heat-sensitive. The culture supernatant of a mutant pneumococcal strain deficient in pneumolysin (Δply) also exhibited the mycelial fragmentation activity. Enolase and lactate oxidase, which are involved in glycolysis and hydrogen peroxide production, were identified in the culture supernatant of the Δply mutant. Neither the wild type nor the mutant strain could fragment the mycelium in the presence of catalase. These data suggest that hydrogen peroxide could fragment the mycelium and would terminate the co-existence of A. fumigatus and S. pneumoniae in biofilm.

Influences of environmental exposures on individuals living with cystic fibrosis

INTRODUCTION

Natural, social, and constructed environments play a critical role in the development and exacerbation of respiratory diseases. However, less is known regarding the influence of these environmental/community risk factors on the health of individuals living with cystic fibrosis (CF), compared to other pulmonary disorders.

AREAS COVERED

Here, we review current knowledge of environmental exposures related to CF, which suggests that environmental/community risk factors do interact with the respiratory tract to affect outcomes. Studies discussed in this review were identified in PubMed between March 2019 and March 2020. Although the limited data available do not suggest that avoiding potentially detrimental exposures other than secondhand smoke could improve outcomes, additional research incorporating novel markers of environmental exposures and community characteristics obtained at localized levels is needed.

EXPERT OPINION

As we outline, some environmental exposures and community characteristics are modifiable; if not by the individual, then by policy. We recommend a variety of strategies to advance understanding of environmental influences on CF disease progression.

Microbial exposure to dairy farmers' dwellings and COPD occurrence

Dairy farming is a risk factor for chronic obstructive pulmonary disease (COPD). The aim was to determine predictive markers either in blood samples or in dwelling dust samples by comparing COPD and healthy controls with or without farming activity. Dust was collected and analyzed by real-time quantitative PCR. ELISA and DELFIA® were performed to assay the level of specific IgG and IgE of 10 targeted microorganisms. The dwelling exposure of farmers was higher than in the non-farmers (Especially Eurotium amstelodami and Lichtheimia corymbifera). The IgG response against Wallemia sebi and Saccharopolyspora rectivirgula was more often higher in the farmers than the non-farmers. However, exposure and sensitization to the microorganisms tested cannot explain the occurrence of COPD in the dairy farmers' population. COPD development is probably caused by multiple factors associated with exposure over a period of several years.

Aspergillus fumigatus in cystic fibrosis: An update on immune interactions and molecular diagnostics in allergic bronchopulmonary aspergillosis

A wide spectrum of pathological conditions may result from the interaction of Aspergillus fumigatus and the immune system of its human host. Allergic bronchopulmonary aspergillosis is one of the most severe A. fumigatus-related diseases due to possible evolution toward pleuropulmonary fibrosis and respiratory failure. Allergic bronchopulmonary aspergillosis occurs almost exclusively in cystic fibrosis or asthmatic patients. An estimated 8%-10% of patients with cystic fibrosis experience this condition. The diagnosis of allergic bronchopulmonary aspergillosis relies on criteria first established in 1977. Progress in the understanding of host-pathogen interactions in A. fumigatus and patients with cystic fibrosis and the ongoing validation of novel laboratory tools concur to update and improve the diagnosis of allergic bronchopulmonary aspergillosis.

DNA metabarcoding to assess indoor fungal communities: Electrostatic dust collectors and Illumina sequencing

DNA metabarcoding is increasingly being used to characterize the microbiological composition of both the indoor and outdoor environments of dwellings. Our study aimed to evaluate metabarcoding and bioinformatic analysis resulting from calibrated samples and samples collected by an electrostatic dust collector (EDC) in dwellings with no moisture problems. Thus, the fungal communities of 14 dwellings (eastern France, Franche-Comté region) were analyzed by Illumina MiSeq technology after amplification of the ITS2 region. Using the standard samples of 11 species of yeasts and molds allowed us to validate the Operational taxonomic units (OTU) assignment. These calibrated samples also showed a low amplification bias, a low rate of sequencing errors and the semi-quantitative nature of the technique. Only one species from the calibrated samples (Lichtheimia corymbifera) was less amplified probably due to the presence of two mismatches in its3 primer. EDC analysis identified 3594OTU with 75% of reads corresponding to 30 genera. The main genera are those usually found by culture techniques (Penicillium, Aspergillus and Cladosporium), but findings also indicate others less commonly isolated in culture such as Epicoccum, the fourth detected genus in our study. The type of heating systems was correlated with fungal diversity. We found less diversity in the dwellings with wood heating and larger quantities of Epicoccum nigrum verified by qPCR. DNA metabarcoding analysis applied to EDC seems promising. However, we think that it must be used along with qPCR, to obtain a more global view of microbial ecology and relative quantification of species of interest within communities.

Proteomics as a Tool to Identify New Targets Against Aspergillus and Scedosporium in the Context of Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disorder that increases the risk of suffering microbial, including fungal, infections. In this paper, proteomics-based information was collated relating to secreted and cell wall proteins with potential medical applications from the most common filamentous fungi in CF, i.e., Aspergillus and Scedosporium/Lomentospora species. Among the Aspergillus fumigatus secreted allergens, β-1,3-endoglucanase, the alkaline protease 1 (Alp1/oryzin), Asp f 2, Asp f 13/15, chitinase, chitosanase, dipeptidyl-peptidase V (DppV), the metalloprotease Asp f 5, mitogillin/Asp f 1, and thioredoxin reductase receive a special mention. In addition, the antigens β-glucosidase 1, catalase, glucan endo-1,3-β-glucosidase EglC, β-1,3-glucanosyltransferases Gel1 and Gel2, and glutaminase A were also identified in secretomes of other Aspergillus species associated with CF: Aspergillus flavus, Aspergillus niger, Aspergillus nidulans, and Aspergillus terreus. Regarding cell wall proteins, cytochrome P450 and eEF-3 were proposed as diagnostic targets, and alkaline protease 2 (Alp2), Asp f 3 (putative peroxiredoxin pmp20), probable glycosidases Asp f 9/Crf1 and Crf2, GPI-anchored protein Ecm33, β-1,3-glucanosyltransferase Gel4, conidial hydrophobin Hyp1/RodA, and secreted aspartyl protease Pep2 as protective vaccines in A. fumigatus. On the other hand, for Scedosporium/Lomentospora species, the heat shock protein Hsp70 stands out as a relevant secreted and cell wall antigen. Additionally, the secreted aspartyl proteinase and an ortholog of Asp f 13, as well as the cell wall endo-1,3-β-D-glucosidase and 1,3-β-glucanosyl transferase, were also found to be significant proteins. In conclusion, proteins mentioned in this review may be promising candidates for developing innovative diagnostic and therapeutic tools for fungal infections in CF patients.

[Infections in cystic fibrosis: Up-to-date]

This review focused on the news in CF airways infection. International guidelines were provided for the care of non tuberculous mycobacteria, and recent studies stressed on the benefit effect of azithromycin or combined antibiotics. The identification of multiresistant environmental bacteria in airways made to account for little-known consequences. Early diagnosis and eradication of Pseudomonas aeruginosa and Staphylococcus aureus methi-R were still a concern, and reports were proposed. However, the studies on staphylococcus methi-R should be interpreted as regards the European or American continent. Thus, levofloxacine has demonstrated its efficacy without enhancing the efficiency. This drug will increase the choice for treating the patient, but no study were provided on the expected modification of the patient microbiota and the known risk of emergent resistance to antibiotics. Lastly, this review underlined that the CF practitioner was encouraged to search and not underestimate the presence of fungus, of which the not so well studied Aspergillus fumigatus.

Medical diagnostics for indoor mold exposure

In April 2016, the German Society of Hygiene, Environmental Medicine and Preventative Medicine (Gesellschaft für Hygiene, Umweltmedizin und Präventivmedizin (GHUP)) together with other scientific medical societies, German and Austrian medical societies, physician unions and experts has provided an AWMF (Association of the Scientific Medical Societies) guideline 'Medical diagnostics for indoor mold exposure'. This guideline shall help physicians to advise and treat patients exposed indoors to mold. Indoor mold growth is a potential health risk, even without a quantitative and/or causal association between the occurrence of individual mold species and health effects. Apart from the allergic bronchopulmonary aspergillosis (ABPA) and the mycoses caused by mold, there is only sufficient evidence for the following associations between moisture/mold damages and different health effects: Allergic respiratory diseases, asthma (manifestation, progression, exacerbation), allergic rhinitis, exogenous allergic alveolitis and respiratory tract infections/bronchitis. In comparison to other environmental allergens, the sensitizing potential of molds is estimated to be low. Recent studies show a prevalence of sensitization of 3-10% in the total population of Europe. The evidence for associations to mucous membrane irritation and atopic eczema (manifestation, progression, exacerbation) is classified as limited or suspected. Inadequate or insufficient evidence for an association is given for COPD, acute idiopathic pulmonary hemorrhage in children, rheumatism/arthritis, sarcoidosis, and cancer. The risk of infections from indoor molds is low for healthy individuals. Only molds that are capable to form toxins can cause intoxications. The environmental and growth conditions and especially the substrate determine whether toxin formation occurs, but indoor air concentrations are always very low. In the case of indoor moisture/mold damages, everyone can be affected by odor effects and/or impairment of well-being. Predisposing factors for odor effects can be given by genetic and hormonal influences, imprinting, context and adaptation effects. Predisposing factors for impairment of well-being are environmental concerns, anxieties, conditioning and attributions as well as a variety of diseases. Risk groups that must be protected are patients with immunosuppression and with mucoviscidosis (cystic fibrosis) with regard to infections and individuals with mucoviscidosis and asthma with regard to allergies. If an association between mold exposure and health effects is suspected, the medical diagnosis includes medical history, physical examination, conventional allergy diagnosis, and if indicated, provocation tests. For the treatment of mold infections, it is referred to the AWMF guidelines for diagnosis and treatment of invasive Aspergillus infections. Regarding mycotoxins, there are currently no validated test methods that could be used in clinical diagnostics. From the perspective of preventive medicine, it is important that mold damages cannot be tolerated in indoor environments.

Aspergillus fumigatus in the cystic fibrosis lung: pros and cons of azole therapy

Aspergillus fumigatus is the main fungus cultured in the airways of patients with cystic fibrosis (CF). Allergic bronchopulmonary aspergillosis occurs in ~10% of CF patients and is clearly associated with airway damage and lung function decline. The effects of A. fumigatus colonization in the absence of allergic bronchopulmonary aspergillosis are less well established. Retrospective clinical studies found associations of A. fumigatus-positive cultures with computed tomography scan abnormalities, greater risk of CF exacerbations and hospitalizations, and/or lung function decline. These findings were somewhat variable among studies and provided only circumstantial evidence for a role of A. fumigatus colonization in CF lung disease progression. The availability of a growing number of oral antifungal triazole drugs, together with the results of nonrandomized case series suggesting positive effects of azole therapies, makes it tempting to treat CF patients with these antifungal drugs. However, the only randomized controlled trial that has used itraconazole in CF patients showed no significant benefit. Because triazoles may have significant adverse effects and drug interactions, and because their prolonged use has been associated with the emergence of azole-resistant A. fumigatus isolates, it remains unclear whether or not CF patients benefit from azole therapy.

Allergic bronchopulmonary aspergillosis is associated with pet ownership in cystic fibrosis

BACKGROUND

Late diagnosis of allergic bronchopulmonary aspergillosis (ABPA) is associated with significant lung function decline and morbidity in cystic fibrosis (CF). The association of ABPA and domestic pet ownership in patients with CF has not been elucidated yet. Our objective was to determine the association of ABPA with pet ownership in patients with CF.

METHODS

Clinical and microbiological data from certified local patient registry were analyzed for 109 patients with CF aged 1-64 years: 55 pet owner and 54 non-pet owners. The primary outcome of the retrospective observational study was the occurrence of ABPA in pet owners and non-pet owners with CF. The free statistical software R was utilized to investigate logistic regression models for association factors.

RESULTS

Of the 109 patients included in the study, 61 (56%) were female. The mean age of the total group was 25.4 ± 13.2 years. Adjusted analysis revealed that ABPA (OR 5.0227, 95% CI: 1.182-21.340, p = 0.029) was associated with pet ownership in patients with CF. Furthermore, ABPA in pet owners with CF was associated with an increased number of exacerbations (OR 6.446, 95% CI: 1.057-39.328, p = 0.043). Other outcomes did not significantly differ.

CONCLUSION

Owning a pet was associated with ABPA in patients with CF. Future prospective multicenter longitudinal studies are needed to investigate chronological causality between pet ownership, ABPA development, and pulmonary exacerbations and to determine whether these estimates are generalizable for ABPA susceptible patients beyond CF (asthma, bronchiectasis).

New Commercially Available IgG Kits and Time-Resolved Fluorometric IgE Assay for Diagnosis of Allergic Bronchopulmonary Aspergillosis in Patients with Cystic Fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is difficult to diagnose; diagnosis relies on clinical, radiological, pathological, and serological criteria. Our aim was to assess the performance of two new commercially available kits and a new in-house assay: an Aspergillus fumigatus enzyme-linked immunosorbent assay (ELISA) IgG kit (Bordier Affinity Products), an Aspergillus Western blotting IgG kit (LDBio Diagnostics), and a new in-house time-resolved fluorometric IgE assay (dissociation-enhanced lanthanide fluorescent immunoassay, or DELFIA) using recombinant proteins from an Aspergillus sp. recently developed by our laboratory for ABPA diagnosis in a retrospective study that included 26 cystic fibrosis patients. Aspergillus fumigatus-specific IgG levels measured by a commercial ELISA kit were in accordance with the level of precipitins currently used in our lab. The ELISA kit could accelerate and help standardize ABPA diagnosis. Aspergillus fumigatus-specific IgE levels measured by ImmunoCAP (Phadia) with A. fumigatus M3 antigen and by DELFIA with a purified protein extract of A. fumigatus were significantly correlated (P < 10(-6)). The results with recombinant antigens glucose-6-phosphate isomerase and mannitol-1-phosphate dehydrogenase were encouraging but must be confirmed with sera from more patients. The DELFIA is an effective tool that can detect specific IgE against more fungal allergens than can be detected with other commercially available tests.