Cara Bossley

Disordered Microbial Communities in Asthmatic Airways

Background A rich microbial environment in infancy protects against asthma [1], [2] and infections precipitate asthma exacerbations [3]. We compared the airway microbiota at three levels in adult patients with asthma, the related condition of COPD, and controls. We also studied bronchial lavage from asthmatic children and controls. Principal Findings We identified 5,054 16S rRNA bacterial sequences from 43 subjects, detecting >70% of species present. The bronchial tree was not sterile, and contained a mean of 2,000 bacterial genomes per cm2 surface sampled. Pathogenic Proteobacteria, particularly Haemophilus spp., were much more frequent in bronchi of adult asthmatics or patients with COPD than controls. We found similar highly significant increases in Proteobacteria in asthmatic children. Conversely, Bacteroidetes, particularly Prevotella spp., were more frequent in controls than adult or child asthmatics or COPD patients. Significance The results show the bronchial tree to contain a characteristic microbiota, and suggest that this microbiota is disturbed in asthmatic airways.

The importance of nurse-led home visits in the assessment of children with problematic asthma

Objective: To evaluate and identify potentially modifiable factors in children with problematic asthma by a nurse-led assessment and home visit. Design: Observational cohort study. Setting: A tertiary paediatric respiratory centre. Patients: 71 children, aged 4.5–17.5 years, with problematic asthma currently under follow-up at a tertiary respiratory centre. Interventions: A nurse-led hospital visit followed by a home visit. Main outcome measures: Identification and attempted change of exacerbating factors so that further investigations and consideration of off-label, potentially toxic, asthma therapies were not necessary. Results: Potentially modifiable factors were identified in 56 (79%) children. Many children had multiple causes for poor control. The most important were ongoing allergen exposure, 22 children (31%); passive or active smoking, 18 children (25%); medication issues including adherence, 34 children (48%); psychosocial factors, 42 families (59%). The home visit contributed valuable information to this assessment. At the home visit house dust mite avoidance measures were found to be inadequate in 84% of those sensitised; medications were not easily available for inspection or were out of date in 23%; 74% of psychology referrals were made after the home visit. In 39 children (55%) the factors identified and the interventions recommended meant that further escalation of treatment was avoided. Conclusions: Nurse-led assessments including a home visit can help identify potentially modifiable factors for poorly controlled symptoms in children with problematic asthma.

IL-33 promotes airway remodeling in pediatric patients with severe steroid-resistant asthma.

BACKGROUND TH2 cytokines are not responsible for the ongoing symptoms and pathology in children with severe therapy-resistant asthma (STRA). IL-33 induces airway hyperresponsiveness, but its role in airway remodeling and steroid resistance is unknown. OBJECTIVE We sought to investigate the relationship between IL-33 and airway remodeling in pediatric patients with STRA. METHODS IL-33 levels were quantified in neonatal mice given inhaled house dust mite (HDM), and the effect of blocking IL-13 on remodeling and IL-33 levels was assessed. HDM-induced allergic airways disease (AAD) in neonatal ST2(-/-) mice lacking the IL-33 receptor was assessed, together with collagen production after IL-33 administration. The effect of steroid therapy on IL-33 levels in patients with neonatal AAD was explored. IL-33 expression was quantified in endobronchial biopsy (EB) specimens from children with STRA and related to remodeling, and collagen production by airway fibroblasts from pediatric patients stimulated with IL-33 and budesonide was quantified. RESULTS Blocking IL-13 after AAD was established in neonatal mice and did not reduce remodeling or IL-33 levels; airway hyperresponsiveness was only partially reduced. IL-33 promoted collagen synthesis both from asthmatic fibroblasts from pediatric patients and after intranasal administration in mice. Increased cellular expression of IL-33, but not IL-13, was associated with increased reticular basement membrane thickness in EB specimens from children with STRA, whereas remodeling was absent in HDM-exposed ST2(-/-) mice. IL-33 levels were maintained, whereas IL-13 levels were abrogated by steroid treatment in neonatal HDM-exposed mice and in EB specimens from children with STRA. CONCLUSION IL-33 is a relatively steroid-resistant mediator that promotes airway remodeling in patients with STRA and is an important therapeutic target.

TSLP polymorphisms are associated with asthma in a sex-specific fashion

To cite this article: Hunninghake GM, Soto‐Quirós ME, Avila L, Kim HP, Lasky‐Su J, Rafaels N, Ruczinski I, Beaty TH, Mathias RA, Barnes KC, Wilk JB, O’Connor GT, James Gauderman W, Vora H, Baurley JW, Gilliland F, Liang C, Sylvia JS, Klanderman BJ, Sharma SS, Himes BE, Bossley CJ, Israel E, Raby BA, Bush A, Choi AM, Weiss ST, Celedón JC. TSLP polymorphisms are associated with asthma in a sex‐specific fashion. Allergy 2010; 65: 1566–1575.

Increased airway smooth muscle in preschool wheezers who have asthma at school age

BACKGROUND Increased airway smooth muscle (ASM) is a feature of established asthma in schoolchildren, but nothing is known about ASM in preschool wheezers. OBJECTIVE We sought to determine endobronchial biopsy specimen ASM area fraction in preschool wheezers and its association with asthma at school age. METHODS ASM area, reticular basement membrane thickness, and mucosal eosinophil and ASM mast cell values were quantified in endobronchial biopsy specimens previously obtained from preschool children undergoing clinically indicated bronchoscopy: severe recurrent wheezers (n=47; median age, 26 months) and nonwheezing control subjects (n=21; median age, 15 months). Children were followed up, and asthma status was established at age 6 to 11 years. Preschool airway pathology was examined in relation to asthma at school age. RESULTS Forty-two (62%) of 68 children had 1 or more evaluable biopsy specimens for ASM. At school age, 51 of 68 children were followed up, and 15 (40%) of 37 preschool wheezers had asthma. Children who had asthma and an evaluable biopsy specimen had increased preschool ASM area fraction (n=8; median age, 8.2 years [range, 6-10.4 years]; median ASM, 0.12 [range, 0.08-0.16]) compared with that seen in children without asthma (n=24; median age, 7.3 years [range, 5.9-11 years]; median ASM, 0.07 [range, 0.02-0.23]; P=.007). However, preschool reticular basement membrane thickness and mucosal eosinophil or ASM mast cell values were not different between those who did or did not have asthma at school age. CONCLUSION Increased preschool ASM is associated with those children who have asthma at school age. Thus a focus on early changes in ASM might be important in understanding the subsequent development of childhood asthma.

High Rhinovirus Burden in Lower Airways of Children With Cystic Fibrosis

BACKGROUND Rhinovirus (RV)-induced pulmonary exacerbations are common in cystic fibrosis (CF) and have been associated with impaired virus clearance by the CF airway epithelium in vitro. Here, we assess in vivo the association of RV prevalence and load with antiviral defense mechanisms, airway inflammation, and lung function parameters in children with CF compared with a control group and children with other chronic respiratory diseases. METHODS RV presence and load were measured by real-time reverse transcription-polymerase chain reaction in BAL samples and were related to antiviral and inflammatory mediators measured in BAL and to clinical parameters. RESULTS BAL samples were obtained from children with CF (n = 195), non-CF bronchiectasis (n = 40), or asthma (n = 29) and from a control group (n = 35) at a median (interquartile range [IQR]) age of 8.2 (4.0-11.7) years. RV was detected in 73 samples (24.4%). RV prevalence was similar among groups. RV load (median [IQR] x 10(3) copies/mL) was higher in children with CF (143.0 [13.1-1530.0]), especially during pulmonary exacerbations, compared with children with asthma (3.0 [1.3-25.8], P = .006) and the control group (0.5 [0.3-0.5], P < .001), but similar to patients with non-CF bronchiectasis (122.1 [2.7-4423.5], P = not significant). In children with CF, RV load was negatively associated with interferon (IFN)- b and IFN- l , IL-1ra levels, and FEV 1 , and positively with levels of the cytokines CXCL8 and CXCL10. CONCLUSIONS RV load in CF BAL is high, especially during exacerbated lung disease. Impaired production of antiviral mediators may lead to the high RV burden in the lower airways of children with CF. Whether high RV load is a cause or a consequence of inflammation needs further investigation in longitudinal studies.

Increased nuclear suppressor of cytokine signaling 1 in asthmatic bronchial epithelium suppresses rhinovirus induction of innate interferons

Background Rhinovirus infections are the dominant cause of asthma exacerbations, and deficient virus induction of IFN-α/β/λ in asthmatic patients is important in asthma exacerbation pathogenesis. Mechanisms causing this interferon deficiency in asthmatic patients are unknown. Objective We sought to investigate the expression of suppressor of cytokine signaling (SOCS) 1 in tissues from asthmatic patients and its possible role in impaired virus-induced interferon induction in these patients. Methods We assessed SOCS1 mRNA and protein levels in vitro, bronchial biopsy specimens, and mice. The role of SOCS1 was inferred by proof-of-concept studies using overexpression with reporter genes and SOCS1-deficient mice. A nuclear role of SOCS1 was shown by using bronchial biopsy staining, overexpression of mutant SOCS1 constructs, and confocal microscopy. SOCS1 levels were also correlated with asthma-related clinical outcomes. Results We report induction of SOCS1 in bronchial epithelial cells (BECs) by asthma exacerbation–related cytokines and by rhinovirus infection in vitro. We found that SOCS1 was increased in vivo in bronchial epithelium and related to asthma severity. SOCS1 expression was also increased in primary BECs from asthmatic patients ex vivo and was related to interferon deficiency and increased viral replication. In primary human epithelium, mouse lung macrophages, and SOCS1-deficient mice, SOCS1 suppressed rhinovirus induction of interferons. Suppression of virus-induced interferon levels was dependent on SOCS1 nuclear translocation but independent of proteasomal degradation of transcription factors. Nuclear SOCS1 levels were also increased in BECs from asthmatic patients. Conclusion We describe a novel mechanism explaining interferon deficiency in asthmatic patients through a novel nuclear function of SOCS1 and identify SOCS1 as an important therapeutic target for asthma exacerbations.

Passive Smoking Impairs Histone Deacetylase-2 in Children With Severe Asthma

Background: Parental smoking is known to worsen asthma symptoms in children and to make them refractory to asthma treatment, but the molecular mechanism is unclear. Oxidative stress from tobacco smoke has been reported to impair histone deacetylase-2 (HDAC2) via phosphoinositide-3-kinase (PI3K)/Akt activation and, thus, to reduce corticosteroid sensitivity. The aim of this study was to investigate passive smoking-dependent molecular abnormalities in alveolar macrophages (AMs) by comparing passive smoke-exposed children and non-passive smoke-exposed children with uncontrolled severe asthma. Methods: BAL fluid (BALF) was obtained from 19 children with uncontrolled severe asthma (10 non-passive smoking-exposed subjects and nine passive smoking-exposed subjects), and HDAC2 expression/activity, Akt/HDAC2 phosphorylation levels, and corticosteroid responsiveness in AMs were evaluated. Results: Parental smoking reduced HDAC2 protein expression by 54% and activity by 47%, with concomitant enhancement of phosphorylation of Akt1 and HDAC2. In addition, phosphorylation levels of Akt1 correlated positively with HDAC2 phosphorylation levels and negatively with HDAC2 activity. Furthermore, passive smoke exposure reduced the inhibitory effects of dexamethasone on tumor necrosis factor-α-induced CXCL8 release in AMs. There were relatively higher neutrophil counts and CXCL8 concentrations in BALF and lower Asthma Control Test scores compared with non-passive smoke-exposed children with uncontrolled severe asthma. Conclusions: Passive smoking impairs HDAC2 function via PI3K signaling activation, which could contribute to corticosteroid-insensitive inflammation in children with severe asthma. This novel mechanism will be a treatment target in children with severe asthma and stresses the need for a smoke-free environment for asthmatic children.

Long-term effectiveness of a staged assessment for paediatric problematic severe asthma

To the Editors: The recently proposed term “problematic severe asthma” (PSA) [1] describes children with persistent symptoms and/or severe exacerbations despite high dose treatment [2]. They suffer significant morbidity and consume a disproportionate amount of healthcare resources. Children with PSA are heterogeneous with respect to lung function [3] and asthma phenotype [4] and warrant careful evaluation. PSA [5] encompasses 1) wrong diagnosis; 2) significant comorbidities; 3) difficult asthma with potentially reversible factors such as poor inhaler technique, ongoing allergen exposure or poor adherence to treatment [6]; and 4) severe therapy-resistant asthma (STRA) that is refractory to maximal treatment despite optimised standard management [7]. PSA children were enrolled in a staged assessment protocol to differentiate difficult asthma from STRA [6]. The different stages were as follows. Stage 1: a detailed re-evaluation of the child including a nurse-led outpatient assessment with evaluation of inhaler device and technique, psychosocial questionnaire, a home and school visit, an assessment of adherence including prescription uptake check and a final multidisciplinary team discussion to decide whether the child had difficult asthma or STRA [6]. Stages 2 and 3: children identified as STRA progressed to invasive investigations including bronchoscopy and assessment of steroid response [7]. Differentiating difficult asthma from STRA is important to avoid unnecessary invasive procedures and side effects from additional treatments such as methotrexate. Furthermore, the healthcare costs of these approaches cannot be justified if simply improving basic management may improve asthma control. There have been no longitudinal studies that have assessed the long-term efficacy of a staged assessment of paediatric PSA. We hypothesised that the stage 1 assessment distinguishes difficult asthma from STRA and results in …

Intraepithelial neutrophils in pediatric severe asthma are associated with better lung function

Background Neutrophils and IL‐17A have been linked mechanistically in models of allergic airways disease and have been associated with asthma severity. However, their role in pediatric asthma is unknown. Objectives We sought to investigate the role of neutrophils and the IL‐17A pathway in mediating pediatric severe therapy‐resistant asthma (STRA). Methods Children with STRA (n = 51; age, 12.6 years; range, 6‐16.3 years) and controls without asthma (n = 15; age, 4.75 years; range, 1.6‐16 years) underwent clinically indicated fiberoptic bronchoscopy, bronchoalveolar lavage (BAL), endobronchial brushings, and biopsy. Neutrophils, IL‐17A, and IL‐17RA–expressing cells and levels of IL‐17A and IL‐22 were quantified in BAL and biopsies and related to clinical features. Primary bronchial epithelial cells were stimulated with IL‐17A and/or IL‐22, with and without budesonide. Results Children with STRA had increased intraepithelial neutrophils, which positively correlated with FEV1 %predicted (r = 0.43; P = .008). Neutrophilhigh patients also had better symptom control, despite lower dose maintenance inhaled steroids. Submucosal neutrophils were not increased in children with STRA. Submucosal and epithelial IL‐17A–positive cells and BAL IL‐17A and IL‐22 levels were similar in children with STRA and controls. However, there were significantly more IL‐17RA–positive cells in the submucosa and epithelium in children with STRA compared with controls (P = .001). Stimulation of primary bronchial epithelial cells with IL‐17A enhanced mRNA expression of IL‐17RA and increased release of IL‐8, even in the presence of budesonide. Conclusions A proportion of children with STRA exhibit increased intraepithelial airway neutrophilia that correlated with better lung function. STRA was also characterized by increased airway IL‐17RA expression. These data suggest a potential beneficial rather than adverse role for neutrophils in pediatric severe asthma pathophysiology.