The Effects of Aspergillus fumigatus Colonization on Lung Function in Patients with Cystic Fibrosis

Fungal lung disease

Fungal lung disease encompasses a wide spectrum of organisms and associated clinical conditions, presenting a significant global health challenge. The type and severity of disease are determined by underlying host immunity and infecting fungal strain. The most common group of diseases are associated with the filamentous fungus Aspergillus species and include allergic bronchopulmonary aspergillosis, sensitisation, aspergilloma and chronic and invasive pulmonary aspergillosis. Fungal lung disease remains epidemiologically heterogenous and is influenced by geography, environment and host comorbidities. Diagnostic modalities continue to evolve and now include novel molecular assays and biomarkers; however, persisting challenges include achieving rapid and accurate diagnosis, particularly in resource-limited settings, and in differentiating fungal infection from other pulmonary conditions. Treatment strategies for fungal lung diseases rely mainly on antifungal agents but the emergence of drug-resistant strains poses a substantial global threat and adds complexity to existing therapeutic challenges. Emerging antifungal agents and increasing insight into the lung mycobiome may offer fresh and personalised approaches to diagnosis and treatment. Innovative methodologies are required to mitigate drug resistance and the adverse effects of treatment. This state-of-the-art review describes the current landscape of fungal lung disease, highlighting key clinical insights, current challenges and emerging approaches for its diagnosis and treatment.

Long-Term Outcomes of Allergic Bronchopulmonary Aspergillosis and Aspergillus Colonization in Children and Adolescents with Cystic Fibrosis

Observational studies indicate that Aspergillus colonization and allergic bronchopulmonary aspergillosis (ABPA) in people with cystic fibrosis (CF) are associated with poorer lung health and increased disease severity. We performed a longitudinal observational cohort study to analyse long-term outcomes of Aspergillus colonization and ABPA in children with CF. Anonymised UK CF Registry data from 2009 to 2019 for patients aged 8-17 years in 2009-2010 were collected. For the baseline cohort analysis, patients were classified based on the presence of Aspergillus colonization and ABPA in 2009 and/or 2010. For the longitudinal analysis, patients were categorised according to annual Aspergillus colonization and ABPA status. Comparisons made were (1) Aspergillus positive vs. negative; (2) excluding those with ABPA: Aspergillus positive vs. negative; and (3) ABPA positive vs. negative. Primary outcome was percentage predicted FEV1 decline and secondary outcomes included BMI decline, mortality, lung transplant, and IV antibiotic use. Of the 1675 children, 263 had Aspergillus colonization in the baseline cohort, 260 were diagnosed with ABPA, and 80 had both. Baseline cohort analysis showed significantly lower lung function (p < 0.0001) and increased antibiotic treatment (p < 0.001) in those with Aspergillus colonization and in those with ABPA. Longitudinal analysis showed ABPA was associated with increased decline in lung function (p < 0.00001) and BMI (p < 0.00001). Aspergillus colonization was associated with increased decline in BMI (p = 0.005) but not lung function (p = 0.30). ABPA was associated with increased decline in long-term lung function and BMI in children and young people with CF. Aspergillus colonization was associated with lower lung function at baseline, but no increased rate of decline was observed long-term.

The airway mycobiome and interactions with immunity in health and chronic lung disease

The existence of commensal fungi that reside within the respiratory tract, termed the airway mycobiome, has only recently been discovered. Studies are beginning to characterize the spectrum of fungi that inhabit the human upper and lower respiratory tract but heterogeneous sampling and analysis techniques have limited the generalizability of findings to date. In this review, we discuss existing studies that have examined the respiratory mycobiota in healthy individuals and in those with inflammatory lung conditions such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. Associations between specific fungi and features of disease pathogenesis are emerging but the precise functional consequences imparted by mycobiota upon the immune system remain poorly understood. It is imperative that further research is conducted in this important area as a more detailed understanding could facilitate the development of novel approaches to manipulating the mycobiome for therapeutic benefit.

Pulmonary Aspergillosis in People with Cystic Fibrosis

In the last decade, fungal respiratory diseases have been increasingly investigated for their impact on the clinical course of people with cystic fibrosis (CF), with a particular focus on infections caused by Aspergillus spp. The most common organisms from this genus detected from respiratory cultures are Aspergillus fumigatus and Aspergillus terreus, followed by Aspergillus flavus, Aspergillus niger, and Aspergillus nidulans. These species have been identified to be both chronic colonizers and sources of active infection and may negatively impact lung function in people with CF. This review article discusses definitions of aspergillosis, challenges in clinical practice, and current literature available for laboratory findings, clinical diagnosis, and treatment options for pulmonary diseases caused by Aspergillus spp. in people with CF.

Invasive Pulmonary Aspergillosis in Patients with and without SARS-CoV-2 Infection

The recent European Confederation of Medical Mycology (ECMM) and the International Society for Human and Animal Mycology (ISHAM) 2020 consensus classification proposes criteria to define coronavirus 2019 (COVID-19)-associated invasive pulmonary aspergillosis (CAPA), including mycological evidence obtained via non-bronchoscopic lavage. Given the low specificity of radiological findings in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, this criterion makes it difficult to differentiate between invasive pulmonary aspergillosis (IPA) and colonization. This unicenter and retrospective study includes 240 patients with isolates of any Aspergillus species in any respiratory samples during a 20-month study (140 IPA and 100 colonization). Mortality was high in the IPA and colonization groups (37.1% and 34.0%, respectively; p = 0.61), especially in patients with SARS-CoV-2 infection, where mortality was higher in colonized patients (40.7% vs. 66.6.%; p: 0.021). Multivariate analysis confirmed the following variables to be independently associated with increased mortality: age > 65 years, acute or chronic renal failure at diagnosis, thrombocytopenia (<100,000 platelets/µL) at admission, inotrope requirement, and SARS-CoV-2 infection, but not the presence of IPA. This series shows that the isolation of Aspergillus spp. in respiratory samples, whether associated with disease criteria or not, is associated with high mortality, especially in patients with SARS-CoV-2 infection, and suggests an early initiation of treatment given its high mortality rate.

Filamentous fungal biofilms: Conserved and unique aspects of extracellular matrix composition, mechanisms of drug resistance and regulatory networks in Aspergillus fumigatus

The filamentous fungus Aspergillus fumigatus is an ubiquitous mold that can cause invasive pulmonary infections in immunocompromised patients. Within the lung, A. fumigatus forms biofilms that can enhance resistance to antifungals and immune defenses, highlighting the importance of defining the mechanisms underlying biofilm development and associated emergent properties. A. fumigatus biofilms display a morphology and architecture that is distinct from bacterial and yeast biofilms. Moreover, A. fumigatus biofilms display unique characteristics in the composition of their extracellular matrix (ECM) and the regulatory networks governing biofilm formation. This review will discuss our current understanding of the form and function of A. fumigatus biofilms, including the unique components of ECM matrix, potential drug resistance mechanisms, the regulatory networks governing A. fumigatus biofilm formation, and potential therapeutics targeting these structures.

Clinical Aspergillus Signatures in COPD and Bronchiectasis

Pulmonary mycoses remain a global threat, causing significant morbidity and mortality. Patients with airways disease, including COPD and bronchiectasis, are at increased risks of pulmonary mycoses and its associated complications. Frequent use of antibiotics and corticosteroids coupled with impaired host defenses predispose patients to fungal colonization and airway persistence, which are associated with negative clinical consequences. Notably, Aspergillus species remain the best-studied fungal pathogen and induce a broad spectrum of clinical manifestations in COPD and bronchiectasis ranging from colonization and sensitization to more invasive disease. Next-generation sequencing (NGS) has gained prominence in the field of respiratory infection, and in some cases is beginning to act as a viable alternative to traditional culture. NGS has revolutionized our understanding of airway microbiota and in particular fungi. In this context, it permits the identification of the previously unculturable, fungal composition, and dynamic change within microbial communities of the airway, including potential roles in chronic respiratory disease. Furthermore, inter-kingdom microbial interactions, including fungi, in conjunction with host immunity have recently been shown to have important clinical roles in COPD and bronchiectasis. In this review, we provide an overview of clinical Aspergillus signatures in COPD and bronchiectasis and cover the current advances in the understanding of the mycobiome in these disease states. The challenges and limitations of NGS will be addressed.

Clinical Impact of Aspergillus fumigatus in Children with Cystic Fibrosis

Background. The clinical relevance of Aspergillus fumigatus (Af) in cystic fibrosis (CF) is controversial. The aims of the study were to assess the prevalence of Af disease in our cohort of CF patients and evaluate whether allergic bronchopulmonary aspergillosis (ABPA) and sensitization to Af affected lung function, body mass index (BMI) and exacerbations. Methods. Clinical data and lung function of CF patients aged 6−18 years followed at the CF Centre of Parma (Italy) were recorded. Patients were classified as: patients with no signs of Af, patients sensitized or colonized by Af, patients with ABPA or patients with Aspergillus bronchitis (Ab). Results. Of 38 CF patients (14.2 years (6.2−18.8) M 23), 8 (21%) showed Af sensitization, 7 (18.4%) showed ABPA, 1 (2.6%) showed Af colonization and 1 (2.6%) showed Ab. Compared to non-ABPA, patients with ABPA had lower BMI (15.9 ± 1.6 vs. 19.7 ± 3.4, p < 0.005), lower lung function (FEV1 61.5 ± 25.9% vs. 92.3 ± 19.3%, p < 0.001) and more exacerbations/year (4.43 ± 2.44 vs. 1.74 ± 2.33, p < 0.005). Patients with Af sensitization showed more exacerbations/year than non-Af patients (3.5 ± 3.2 vs. 0.9 ± 1.2, p < 0.005). ABPA and sensitized patients had more abnormalities on chest CT scans. Conclusion. This study showed the relevant clinical impact of ABPA and Af sensitization in terms of exacerbations and lung structural damage.