Antifungals in severe asthma

Fungal bronchitis is a distinct clinical entity which is responsive to antifungal therapy

Chronic productive cough in the context of exacerbations of airway disease can be associated with positive sputum cultures for fungi, in particular Aspergillus fumigatus and Candida spp., suggesting fungal bronchitis, a condition not widely recognised, as a possible cause for the exacerbation. Our objective was to determine the response to antifungal therapy in patients with suspected fungal bronchitis. Retrospective analysis of data extracted from case records of patients under secondary care respiratory clinics who had been treated with triazole therapy for suspected fungal bronchitis between 2010–2017. Primary outcome was lung function response after 1 month of treatment. Nineteen patients with fungal bronchitis due to A. fumigatus and 12 patients due to Candida spp., were included in the study. Most of the patients, particularly in the Aspergillus group, had allergic fungal airway disease on a background of asthma. All but one of the patients in each group were recorded as showing clinical improvement with antifungal therapy. In the majority of patients this was reflected in an improvement in lung function. Aspergillus group: FEV₁ (1.44 ± 0.8 L vs 1.6 ± 0.8 L: p < 0.02), FVC (2.49 ± 1.08 L vs 2.8 ± 1.1 L: p = 0.01), and PEF (260 ± 150L/min vs 297 ± 194ml/min: p < 0.02). Candida group: FEV₁ (1.6 ± 0.76 L vs 2.0 ± 0.72 L: p < 0.004), FVC (2.69 ± 0.91 L vs 3.13 ± 0.7 L: p = 0.05), and PEF (271± 139L/min vs 333 ± 156 L/min: p = 0.01). Side effects of treatment were common, but resolved on stopping treatment. This service improvement project supports the idea that fungal bronchitis is a distinct clinical entity which is responsive to treatment. Controlled clinical trials to confirm the clinical impression that this is relatively common and treatable complication of complex airway disease are required.

The impact of fungal allergic sensitization on asthma

PURPOSE OF REVIEW

Fungal sensitization may contribute to the development of asthma as well as asthma severity. The purpose of this review is to summarize existing knowledge about the pathophysiology, diagnosis, and management of fungal sensitization in asthma and highlight unmet needs and target areas for future investigation.

RECENT FINDINGS

Fungal sensitization may occur by a normal or aberrant immune response. Allergic sensitization to fungi is mediated by the adaptive immune response driven by TH2 cells and the innate immune response driven by the innate lymphoid cells group 2. Diagnosis of fungal sensitization can be made by either skin prick testing or measurement of fungal-specific serum IgE. Fungal sensitization in asthma has been associated with worse disease severity, including reduced lung function, increased risk of hospitalizations, and life-threatening asthma. A spectrum of disease related to fungal sensitization has been described in asthma including allergic bronchopulmonary mycosis and severe asthma with fungal sensitization (SAFS). The role of antifungals and targeted biologic therapy in asthma with fungal sensitization need further investigation.

SUMMARY

There is increasing awareness of the contribution of fungal sensitization to asthma severity. However, there are no therapies with proven efficacy. Randomized clinical trials are needed to further investigate the role of biologics.

The Fungal Microbiome and Asthma

Asthma is a group of inflammatory conditions that compromises the airways of a continuously increasing number of people around the globe. Its complex etiology comprises both genetic and environmental aspects, with the intestinal and lung microbiomes emerging as newly implicated factors that can drive and aggravate asthma. Longitudinal infant cohort studies combined with mechanistic studies in animal models have identified microbial signatures causally associated with subsequent asthma risk. The recent inclusion of fungi in human microbiome surveys has revealed that microbiome signatures associated with asthma risk are not limited to bacteria, and that fungi are also implicated in asthma development in susceptible individuals. In this review, we examine the unique properties of human-associated and environmental fungi, which confer them the ability to influence immune development and allergic responses. The important contribution of fungi to asthma development and exacerbations prompts for their inclusion in current and future asthma studies in humans and animal models.

Aspergillus fumigatus Protease Alkaline Protease 1 (Alp1): A New Therapeutic Target for Fungal Asthma

We review three recent findings that have fundamentally altered our understanding of causative mechanisms underlying fungal-related asthma. These mechanisms may be partially independent of host inflammatory processes but are strongly dependent upon the actions of Alp1 on lung structural cells. They entail (i) bronchial epithelial sensing of Alp1; (ii) Alp1-induced airway smooth muscle (ASM) contraction; (iii) Alp1-induced airflow obstruction. Collectively, these mechanisms point to Alp1 as a new target for intervention in fungal asthma.

The Fungal Microbiome and Asthma

Asthma is a group of inflammatory conditions that compromises the airways of a continuously increasing number of people around the globe. Its complex etiology comprises both genetic and environmental aspects, with the intestinal and lung microbiomes emerging as newly implicated factors that can drive and aggravate asthma. Longitudinal infant cohort studies combined with mechanistic studies in animal models have identified microbial signatures causally associated with subsequent asthma risk. The recent inclusion of fungi in human microbiome surveys has revealed that microbiome signatures associated with asthma risk are not limited to bacteria, and that fungi are also implicated in asthma development in susceptible individuals. In this review, we examine the unique properties of human-associated and environmental fungi, which confer them the ability to influence immune development and allergic responses. The important contribution of fungi to asthma development and exacerbations prompts for their inclusion in current and future asthma studies in humans and animal models.

Long-term effect of antifungal therapy for the treatment of severe resistant asthma: an active comparator clinical trial

Background and Purpose:

Itraconazole therapy has been reported to control asthma in severe therapy-resistant asthma with fungal sensitization. The aim of this study was to investigate the impact of anti-fungal therapy on the treatment of severe asthma, irrespective of sensitization.

Materials and Methods:

This active comparator clinical trial was performed on 110 therapy-resistant asthmatic patients who were randomly assigned into two groups of case and control. The patients in the case group were administered 200 mg itraconazole twice a day and the control group received 10 mg prednisolone after breakfast for 4 months. The asthma control test (ACT) which was used as a marker for the global evaluation of treatment effectiveness (GETE) was applied as the primary endpoint parameter. Cough, dyspnea, and sleep disturbance were measured on a scale of 1-4, with 1 representing no symptom and 4 indicating severe exhausting disturbance.

Results:

Based on the obtained results, 71% of the itraconazole group demonstrated a marked improvement in the GETE score after a four-month treatment. Itraconazole was able to suppress clinical symptoms, including cough, dyspnea, and night symptoms, and their physical exam was indicative of normalization in 60% of the patients. On the other hand, the patients in the parallel group "prednisolone" were only able to control dyspnea. The ACT score represented a notable improvement with itraconazole (mean: 14 before the trial and >20 after the trial) and spirometry parameters underwent a considerable change from obstructive pattern to normal. Furthermore, adverse effects were only detected in 6% of itraconazole users.

Conclusion:

The results of this clinical trial indicted the effectiveness of antifungal therapy for the control of the clinical condition of a subgroup of patients with severe steroid-refractory asthma.

A Practical Approach to Severe Asthma in Children

Severe asthma accounts for only a small proportion of the children with asthma but a disproportionately high amount of resource utilization and morbidity. It is a heterogeneous entity and requires a step-wise, evidence-based approach to evaluation and management by pediatric subspecialists. The first step is to confirm the diagnosis by eliciting confirmatory history and objective evidence of asthma and excluding possible masquerading diagnoses. The next step is to differentiate difficult-to-treat asthma, asthma that can be controlled with appropriate management, from asthma that requires the highest level of therapy to maintain control or remains uncontrolled despite management optimization. Evaluation of difficult-to-treat asthma includes an assessment of medication delivery, the home environment, and, if possible, the school and other frequented locations, the psychosocial situation, and comorbid conditions. Once identified, aggressive management of issues related to poor adherence and drug delivery, remediation of environmental triggers, and treatment of comorbid conditions is necessary to characterize the degree of control that can be achieved with standard therapies. For the small proportion of patients whose disease remains poorly controlled with these interventions, the clinician may assess steroid responsiveness and determine the inflammatory pattern and eligibility for biologic therapies. Management of severe asthma refractory to traditional therapies involves considering the various biologic and other newly approved treatments as well as emerging therapies based on the individual patient characteristics.

Treating Pediatric Asthma According Guidelines

Asthma is a common chronic inflammatory disorder of the lower respiratory airways in childhood. The management of asthma exacerbations and the disease control are major concerns for clinical practice. The Global Strategy for Asthma Management and Prevention, published by GINA, updated in 2017, the British Thoracic Society/Scottish Intercollegiate Guideline Network, revised in 2016, the National Institute for Health and Care Excellence asthma guideline consultation, available in 2017, are widely accepted documents, frequently implemented, with conflicting advices, and different conclusion on asthma definition and treatment. An International Consensus on Pediatric Asthma was carried out in 2012 by a Committee with expertise in the field, to critically review differences on current guidelines. In addition, the specific issue of treating severe and difficult asthma has been recently highlighted throughout the International European Respiratory Society/American Thoracic Society guidelines on severe asthma. The aim of this paper is to describe conventional treatments and some new therapeutic approaches to pediatric asthma according to guidelines, highlighting key aspects, and differences on proposed clinical recommendations for asthma management. Age specific therapy are proposed in steps, according to clinical severity and the level of disease control. If control is not achieved within 3 months, stepping-up should be considered; otherwise, if control is achieved after 3 months, stepping down may be considered. The most used drug classes of asthma medications are beta-2 adrenergic agonists, corticosteroids, and leukotriene modifiers. Intramuscolar triamcinolone has been used for severe asthma treatment. Chromones and xanthines have been extensively used in the past, but they have shown limits related to their efficacy and safety profile. Omalizumab, a monoclonal antibody against IgE, is an immunomodulatory biological agent, used as new drug in patients with confirmed IgE-mediated allergic asthma, only for patient's specific range of total IgE level. There are low evidences in the efficacy of metotrexate, as well as macrolide antibiotics in children with asthma. Antifungal agents are also not recommended in asthmatic patients. Non-pharmacological measures that may improve patient's quality of life should also be attempted. We conclude that treatment decisions on childhood asthma management should be critically made, pondering the differences suggested by agreed international consensus documents.

Diagnosis and treatment of severe asthma: a phenotype-based approach

Severe asthma is a heterogeneous and often difficult to treat condition that results in a disproportionate cost to healthcare systems. Appropriate diagnosis and management of severe asthma is critical, as most asthma deaths have been retrospectively identified as having poorly recognised severe asthma. With multiple biologic agents becoming available, it is crucial to correctly phenotype patients in order to identify those that will respond to these high-cost treatments. We provide an overview of the assessment, phenotyping and management of severe asthma in primary and secondary care.

New Drugs for Pediatric Asthma

Asthma is the most common chronic disease in children. As suggested by international guidelines, the main goals of asthma treatment are symptoms control and lung function preservation, through a stepwise and control-based approach. The first line therapy based on inhaled corticosteroids may fail to reach control in more than one third of patients, especially adolescents, and in these lung function and quality of life may progressively worsen. Treatment with omalizumab, the first anti-immunoglobulin E recombinant humanized monoclonal antibody, has been definitely approved in pediatric uncontrolled asthma. In this review, we discuss the mechanisms and potential roles of emerging therapies for pediatric severe asthma. Novel biologic drugs (i.e., dupilumab, mepolizumab, reslizumab, and benralizumab) seem to be promising in reducing annual exacerbation rates and steroid-use in glucocorticoid-dependent cases, but available data are few and limited to adolescents and adults. Evidences on the use of the muscarinic antagonist tiotropium as controller medication in pediatric settings are progressively growing, sustaining an application as asthma maintenance treatment in children aged >6 years and in preschool children with persistent asthmatic symptoms, but well powered trials are needed to confirm its safety and efficacy. New inhaled corticosteroids (i.e., ciclesonide and mometasone) are effective as once-daily controller therapy, but long-term studies in the different pediatric ages are needed to compare effectiveness and safety to usual treatments. At present, the role of macrolides in pediatric severe asthma is controversial and their administration is not recommended routinely, but may be considered in children with neutrophilic asthma for reducing daily oral steroids administration and improving lung function. Despite the availability of several novel therapeutic strategies for uncontrolled asthma, future trials targeted at specific pediatric age subgroups are needed to support evidences of safety and efficacy also in children.

Pathogenesis and prevention strategies of severe asthma exacerbations in children

PURPOSE OF REVIEW

Exacerbations of asthma in children are most frequently precipitated by respiratory infections with a seasonal pattern. However, management takes little account of the underlying infective or other precipitant abnormality.

RECENT FINDINGS

Interactions between environmental triggers, the airway microbiome and innate immune responses are key determinants of exacerbations. Elevated innate cytokines interleukin (IL)-33 and IL-25, and abnormal molecular responses in the interferon pathway are associated with rhinoviral infections. Exacerbations caused by fungal allergens also induce IL-33, highlighting this as an attractive therapeutic target. An equal contribution of bacterial and viral infection during exacerbations, particularly in preschool children, has become increasingly apparent, but some organisms may be protective. Investigation of mechanisms underlying infection-related exacerbations especially in preschool children is needed.Progressive loss of lung function from exacerbations is most pronounced in children aged 6-11 years, and low FEV1 is now recognized as a key predictor for the development of chronic obstructive pulmonary disease and premature death. Although prevention of exacerbations is critical, suboptimal patient education, prescription and adherence to maintenance therapy, and a lack of predictive biomarkers, remain key unaddressed issues in children.

SUMMARY

Precipitants and predictors of exacerbations, together with the child's age and clinical phenotype, need to be used to achieve individualized management in preference to the current uniform approach for all.

The changing face of asthma and its relation with microbes

During the past 50 years, the prevalence of asthma has increased and this has coincided with our changing relation with microorganisms. Asthma is a complex disease associated with local tissue inflammation of the airway that is determined by environmental, immunological, and host genetic factors. In a subgroup of sufferers, respiratory infections are associated with the development of chronic disease and more frequent inflammatory exacerbations. Recent studies suggest that these infections are polymicrobial in nature. Furthermore, there is increasing evidence that the recently discovered asthma airway microbiota may play a critical role in pathophysiological processes associated with the disease. Here, we discuss the current data regarding a possible role for infection in chronic asthma with a particular focus on the role bacteria may play. We discuss recent advances that are beginning to elucidate the complex relations between the microbiota and the immune response in asthma patients. We also highlight the clinical implications of these recent findings in regards to the development of novel therapeutic strategies.