Purpose of review
To describe a prospective classification for preschool wheezers according to temporal symptom pattern, and summarise findings relating to the management of viral wheeze and the use of short term therapy for intermittent severe wheeze.
Phenotypes defined from cohort studies should only be applied retrospectively at school-age. A new classification that can be applied prospectively is discussed. The importance of early rhinovirus induced wheezing as a risk factor for asthma has become apparent. However, there is no benefit from short-course oral steroids for acute viral wheeze in the majority of cases. There is conflicting evidence for the role of intermittent montelukast or inhaled steroids in the treatment of acute, intermittent wheeze. A link between reduced vitamin D intake during pregnancy and increased preschool wheeze in offspring has emerged, suggesting a potential role for vitamin D supplementation in primary prevention.
Based on current evidence, a trial of bronchodilators is first line therapy for viral wheeze, and maintenance montelukast or inhaled steroids may be considered in preschool wheezers with persistent symptoms and risk factors for future asthma. No disease modifying therapies are available. New therapeutic options for preschool wheezing disorders are desperately needed.
preschool wheeze; management; diagnosis; phenotypes
This study tested cognitive behavior therapy (CBT) in hypnotic-dependent, late middle-age and older adults with insomnia.
Seventy volunteers age 50 and older were randomized to CBT plus drug withdrawal, placebo biofeedback (PL) plus drug withdrawal, or drug withdrawal (MED) only. The CBT and PL groups received eight, 45 minute weekly treatment sessions. The drug withdrawal protocol comprised slow tapering monitored with about six biweekly, 30 minute sessions. Assessment including polysomnography (PSG), sleep diaries, hypnotic consumption, daytime functioning questionnaires, and drug screens collected at baseline, posttreatment, and 1-year follow-up.
Only the CBT group showed significant sleep diary improvement, sleep onset latency significantly decreased at posttreatment. For all sleep diary measures for all groups, including MED, sleep trended to improvement from baseline to follow-up. Most PSG sleep variables did not significantly change. There were no significant between group differences in medication reduction. Compared to baseline, the three groups decreased hypnotic use at posttreatment, down 84%, and follow-up, down 66%. There was no evidence of withdrawal side-effects. Daytime functioning, including anxiety and depression, improved by posttreatment. Rigorous methodological features, including documentation of strong treatment implementation and the presence of a credible placebo, elevated the confidence due these findings.
Gradual drug withdrawal was associated with substantial hypnotic reduction at posttreatment and follow-up, and withdrawal side-effects were absent. When supplemented with CBT, participants accrued incremental self-reported, but not PSG, sleep benefits.
hypnotic dependence; drug withdrawal; insomnia; cognitive behavior therapy
Th2 cytokines are not responsible for the on-going symptoms and pathology in children with severe therapy resistant asthma (STRA). Interleukin (IL)-33 induces airway hyperresponsiveness (AHR), but its role in airway remodelling and steroid resistance is unknown.
To investigate the relationship between IL-33 and airway remodelling in paediatric STRA.
IL-33 was quantified in neonatal mice given inhaled house dust mite (HDM), and the effect of blocking IL-13 on remodelling and IL-33 was assessed. HDM induced allergic airways disease (AAD) in neonatal ST2−/− mice lacking the IL-33 receptor was assessed, together with collagen production following IL-33 administration. Impact of steroid therapy on IL-33 levels in neonatal AAD was explored. IL-33 expression was quantified in endobronchial biopsies from children with STRA and related to remodelling, and collagen production by paediatric airway fibroblasts stimulated with IL-33 and budesonide quantified.
Blocking IL-13 after AAD was established in neonatal mice did not reduce remodelling or IL-33 levels; AHR was only partially reduced. IL-33 promoted collagen synthesis both from paediatric asthmatic fibroblasts, and following intra-nasal administration in mice. Increased cellular expression of IL-33, but not IL-13, was associated with increased reticular basement membrane thickness in endobronchial biopsies from children with STRA, whilst remodelling was absent in HDM exposed ST2−/− mice. IL-33 was maintained whilst IL-13 was abrogated by steroid treatment in neonatal HDM exposed mice, and in endobronchial biopsies from children with STRA.
IL-33 is a relatively steroid resistant mediator that promotes airway remodelling in STRA, and is an important therapeutic target.
Asthma; paediatric; airway remodelling; steroid resistance; IL-33; therapy
Rationale: Mutations in genes encoding proteins important in the function and metabolism of pulmonary surfactant are recognized causes of lung disease. Clinical genetic testing is available for these disorders, but children with phenotypes consistent with surfactant dysfunction and no identifiable mutations in the known causative genes have been reported.
Objectives: To identify the mechanism(s) for lung disease in two children with the phenotype of surfactant dysfunction who had negative testing in clinical laboratories for gene mutations causing surfactant dysfunction.
Methods: Amplicons spanning multiple exons of candidate genes were generated by polymerase chain reaction and sequenced.
Measurements and Main Results: A 4,335-base deletion that included all of exon 12 of the gene encoding member A3 of the adenosine triphosphate–binding cassette transporter was identified in a full-term infant with respiratory failure. A 333-base deletion involving part of exon 4 and the adjacent intron of the gene encoding surfactant protein C was identified in a child with interstitial lung disease.
Conclusions: Large deletions are a cause of surfactant dysfunction disorders and may need to be sought for specifically in children whose phenotypes suggest these syndromes but in whom clinical genetic testing is unrevealing.
pulmonary surfactant; respiratory distress syndrome; interstitial lung disease; genetic basis of disease
Rationale: Lung clearance index (LCI) is a more sensitive measure of lung function than spirometry in cystic fibrosis (CF) and correlates well with abnormalities in high-resolution computed tomography (HRCT) scanning. We hypothesized LCI would be equally sensitive to lung disease in primary ciliary dyskinesia (PCD).
Objectives: To test the relationships between LCI, spirometry, and HRCT in PCD and to compare them to the established relationships in CF.
Methods: Cross-sectional study of 127 patients with CF and 33 patients with PCD, all of whom had spirometry and LCI, of which a subset of 21 of each had HRCT performed. HRCT was scored for individual features and these features compared with physiological parameters.
Measurements and Main Results: Unlike in CF, and contrary to our hypothesis, there was no correlation between spirometry and LCI in PCD and no correlation between HRCT features and LCI or spirometry in PCD.
Conclusions: We show for the first time that HRCT, spirometry, and LCI have different relationships in different airway diseases and that LCI does not appear to be a sensitive test of airway disease in advanced PCD. We hypothesize that this results from dissimilarities between the components of large and small airway disease in CF and PCD. These differences may in part lead to the different prognosis in these two neutrophilic airway diseases.
spirometry; high-resolution computed tomography; lung clearance index
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.
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.
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.
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.
There are few effective obesity interventions directed towards younger children, particularly young minority children. This paper describes the design, intervention, recruitment methods, and baseline data of the ongoing Positive Lifestyles for Active Youngsters (Team PLAY) study. This randomized controlled trial is designed to test the efficacy of a 6-month, moderately intense, primary care feasible, family-based behavioral intervention, targeting both young children and their parent, in promoting healthy weight change.
Participants are 270 overweight and obese children (ages 4 to 7 years) and their parent, who were recruited from a primarily African American urban population. Parents and children were instructed in proven cognitive behavioral techniques (e.g. goal setting, self-talk, stimulus control and reinforcement) designed to encourage healthier food choices (more whole grains, fruits and vegetables, and less concentrated fats and sugar), reduce portion sizes, decrease sweetened beverages and increase moderate to vigorous physical activity engagement. The main outcome of this study is change in BMI at two years post enrollment.
Recruitment using reactive methods (mailings, TV ads, pamphlets) was found to be more successful than using only a proactive approach (referral through physicians). At baseline, most children were very obese with an average BMI z-score of 2.6. Reported intake of fruits and vegetables and minutes of moderate to vigorous physical activity engagement did not meet national recommendations. If efficacious, Team PLAY would offer a model for obesity treatment directed at families with young children that could be tested and translated to both community and primary care settings.
randomized controlled trial; children; obesity
The ecological traits and functional capabilities of marine animals have changed significantly since their origin in the late Precambrian. These changes can be analysed quantitatively using multi-dimensional parameter spaces in which the ecological lifestyles of species are represented by particular combinations of parameter values. Here, we present models that describe the filling of this multi-dimensional ‘ecospace’ by ecological lifestyles during metazoan diversification. These models reflect varying assumptions about the processes that drove ecological diversification; they contrast diffusive expansion with driven expansion and niche conservatism with niche partitioning. Some models highlight the importance of interactions among organisms (ecosystem engineering and predator–prey escalation) in promoting new lifestyles or eliminating existing ones. These models reflect processes that were not mutually exclusive; rigorous analyses will continue to reveal their applicability to episodes in metazoan history.
ecospace utilization; diversification; Phanerozoic; functional diversity; macroevolution; Metazoa
Children who are referred to specialist care with asthma that does not respond to treatment (problematic severe asthma) are a heterogeneous group, with substantial morbidity. The evidence base for management is sparse, and is mostly based on data from studies in children with mild and moderate asthma and on extrapolation of data from studies in adults with severe asthma. In many children with severe asthma, the diagnosis is wrong or adherence to treatment is poor. The first step is a detailed diagnostic assessment to exclude an alternative diagnosis (“not asthma at all”), followed by a multidisciplinary approach to exclude comorbidities (“asthma plus”) and to assess whether the child has difficult asthma (improves when the basic management needs, such as adherence and inhaler technique, are corrected) or true, therapy-resistant asthma (still symptomatic even when the basic management needs are resolved). In particular, environmental causes of secondary steroid resistance should be identified. An individualised treatment plan should be devised depending on the clinical and pathophysiological characterisation. Licensed therapeutic approaches include high-dose inhaled steroids, the Symbicort maintenance and reliever (SMART) regimen (with budesonide and formoterol fumarate), and anti-IgE therapy. Unlicensed treatments include methotrexate, azathioprine, ciclosporin, and subcutaneous terbutaline infusions. Paediatric data are needed on cytokine-specific monoclonal antibody therapies and bronchial thermoplasty. However, despite the interest in innovative approaches, getting the basics right in children with apparently severe asthma will remain the foundation of management for the foreseeable future.
Little is known about vitamin D status and its effect on asthma pathophysiology in children with severe, therapy-resistant asthma (STRA).
Relationships between serum vitamin D, lung function, and pathology were investigated in pediatric STRA.
Serum 25-hydroxyvitamin D [25(OH)D3] was measured in 86 children (mean age, 11.7 yr): 36 with STRA, 26 with moderate asthma (MA), and 24 without asthma (control subjects). Relationships between 25(OH)D3, the asthma control test (ACT), spirometry, corticosteroid use, and exacerbations were assessed. Twenty-two of 36 children with STRA underwent fiberoptic bronchoscopy, bronchoalveolar lavage, and endobronchial biopsy with assessment of airway inflammation and remodeling.
Measurements and Main Results
25(OH)D3 levels (median [IQR]) were significantly lower in STRA (28 [22–38] nmol/L) than in MA (42.5 [29–63] nmol/L) and control subjects (56.5 [45–67] nmol/L) (P < 0.001). There was a positive relationship between 25(OH)D3 levels and percent predicted FEV1 (r = 0.4, P < 0.001) and FVC (r = 0.3, P = 0.002) in all subjects. 25(OH)D3 levels were positively associated with ACT (r = 0.6, P < 0.001), and inversely associated with exacerbations (r=−0.6, P < 0.001) and inhaled steroid dose (r=−0.39, P = 0.001) in MA and and STRA. Airway smooth muscle (ASM) mass, but not epithelial shedding or reticular basement membrane thickness, was inversely related to 25(OH)D3 levels (r=−0.6, P = 0.008). There was a positive correlation between ASM mass and bronchodilator reversibility (r = 0.6, P = 0.009) and an inverse correlation between ASM mass and ACT (r = −0.7, P < 0.001).
Lower vitamin D levels in children with STRA were associated with increased ASM mass and worse asthma control and lung function. The link between vitamin D, airway structure, and function suggests vitamin D supplementation may be useful in pediatric STRA.
vitamin D; asthma; remodeling; airway smooth muscle; pediatrics
CD200, a cell-surface immunoglobulin-like molecule expressed by immune and stromal cells, dampens the pro-inflammatory activity of tissue-resident innate cells via its receptor, CD200R. This interaction appears critical for peripheral immune tolerance, particularly in the airways where excessive inflammation is undesirable. Vitamin D contributes to pulmonary health and promotes regulatory immune pathways, therefore its influence on CD200 and CD200R was investigated.
CD200 and CD200R expression were assessed by qPCR and immunoreactivity of human lymphoid, myeloid and epithelial cells following 1α,25-dihydroxyvitamin D3 (1α,25VitD3) exposure in vitro and in peripheral T cells following 1α,25VitD3 oral ingestion in vivo. The effect of 1α25VitD3 was also assessed in human airway-resident cells.
1α25VitD3 potently upregulated CD200 on peripheral human CD4+ T cells in vitro, and in vivo there was a trend towards upregulation in healthy, but not asthmatic individuals. CD200R expression was not modulated in any cells studied. CD200 induction was observed to a lesser extent in CD8+ T cells and not in B cells or airway epithelium. T cells isolated from the human airway also responded strongly to 1α25VitD3 to upregulate CD200.
The capacity of 1α,25-dihydroxyvitamin D3 to induce CD200 expression by peripheral and respiratory tract T cells identifies an additional pathway via which vitamin D can restrain inflammation in the airways to maintain respiratory health.
The bronchial epithelium and underlying reticular basement membrane (RBM) have a close spatial and functional inter-relationship and are considered an epithelial–mesenchymal trophic unit (EMTU). An understanding of RBM development is critical to understanding the extent and time of appearance of its abnormal thickening that is characteristic of asthma.
RBM thickness and epithelial height were determined in histological sections of cartilaginous bronchi obtained postmortem from 47 preterm babies and infants (median age 40 weeks gestation (22 weeks gestation–8 months)), 40 children (2 years (1 month–17 years)) and 23 adults (44 (17–90) years) who had died from non-respiratory causes, and had no history of asthma.
The RBM was visible by light microscopy at 30 weeks gestation. RBM thickness increased in successive age groups in childhood; in infants (r=0.63, p<0.001) and in children between 1 month and 17 years (r=0.82, p<0.001). After 18 years, RBM thickness decreased with increasing age (r=−0.42, p<0.05). Epithelial height showed a similar relationship with age, a positive relationship from preterm to 17 years (r = 0.50, p<0.001) and a negative relationship in adulthood (r=−0.84, p<0.0001). There was a direct relationship between epithelial height and RBM thickness (r=0.6, p<0.001).
The RBM in these subjects was microscopically identifiable by 30 weeks gestation. It thickened during childhood and adolescence. In adults, there was either no relationship with age, or a slow reduction in thickness in older age. Developmental changes of RBM thickness were accompanied by similar changes in epithelial height, supporting the close relationship between RBM and epithelium within the EMTU.
1α,25-Dihydroxyvitamin D3 (1α25VitD3) has potent immunomodulatory properties. We have previously demonstrated that 1α25VitD3 promotes human and murine IL-10-secreting CD4+ T cells. Because of the clinical relevance of this observation, we characterized these cells further and investigated their relationship with Foxp3+ regulatory T (Treg) cells. 1α25VitD3 increased the frequency of both Foxp3+ and IL-10+ CD4+T cells in vitro. However, Foxp3 was increased at high concentrations of 1α25VitD3 and IL-10 at more moderate levels, with little coexpression of these molecules. The Foxp3+ and IL-10+ T-cell populations showed comparable suppressive activity. We demonstrate that the enhancement of Foxp3 expression by 1α25VitD3 is impaired by IL-10. 1α25VitD3 enables the selective expansion of Foxp3+ Treg cells over their Foxp3− T-cell counterparts. Equally, 1α25VitD3 maintains Foxp3+ expression by sorted populations of human and murine Treg cells upon in vitro culture. A positive in vivo correlation between vitamin D status and CD4+Foxp3+ T cells in the airways was observed in a severe pediatric asthma cohort, supporting the in vitro observations. In summary, we provide evidence that 1α25VitD3 enhances the frequency of both IL-10+ and Foxp3+ Treg cells. In a translational setting, these data suggest that 1α25VitD3, over a broad concentration range, will be effective in enhancing the frequency of Treg cells.
1α,25-Dihydroxyvitamin D3; Asthma; Immune regulation; Regulatory T cells
Background: Lipoxygenases (LOXs) generate eicosanoids in inflammation.
Results: Monocyte/macrophage LOXs generate novel phospholipid-esterified eicosanoids containing ketoeicosatetraenoic acid or hydroperoxyeicosatetraenoic acid. They activate peroxisome proliferator-activated receptor-γ transcriptional activity and are found in cystic fibrosis bronchoalveolar fluid.
Significance: LOXs generate esterified eicosanoids in vitro and in vivo.
Conclusion: These new lipids represent new families of bioactive mediators.
12/15-Lipoxygenases (LOXs) in monocytes and macrophages generate novel phospholipid-esterified eicosanoids. Here, we report the generation of two additional families of related lipids comprising 15-ketoeicosatetraenoic acid (KETE) attached to four phosphatidylethanolamines (PEs). The lipids are generated basally by 15-LOX in IL-4-stimulated monocytes, are elevated on calcium mobilization, and are detected at increased levels in bronchoalveolar lavage fluid from cystic fibrosis patients (3.6 ng/ml of lavage). Murine peritoneal macrophages generate 12-KETE-PEs, which are absent in 12/15-LOX-deficient mice. Inhibition of 15-prostaglandin dehydrogenase prevents their formation from exogenous 15-hydroxyeicosatetraenoic acid-PE in human monocytes. Both human and murine cells also generated analogous hydroperoxyeicosatetraenoic acid-PEs. The electrophilic reactivity of KETE-PEs is shown by their Michael addition to glutathione and cysteine. Lastly, both 15-hydroxyeicosatetraenoic acid-PE and 15-KETE-PE activated peroxisome proliferator-activated receptor-γ reporter activity in macrophages in a dose-dependent manner. In summary, we demonstrate novel peroxisome proliferator-activated receptor-γ-activating oxidized phospholipids generated enzymatically by LOX and 15-prostaglandin dehydrogenase in primary monocytic cells and in a human Th2-related lung disease. The lipids are a new family of bioactive mediators from the 12/15-LOX pathway that may contribute to its known anti-inflammatory actions in vivo.
Eicosanoid; Innate Immunity; Lipoxygenase Pathway; Macrophages; Mass Spectrometry (MS); Monocytes; Phospholipid
The pathology of pediatric severe therapy-resistant asthma (STRA) is little understood.
We hypothesized that STRA in children is characterized by airway eosinophilia and mast cell inflammation and is driven by the TH2 cytokines IL-4, IL-5, and IL-13.
Sixty-nine children (mean age, 11.8 years; interquartile range, 5.6-17.3 years; patients with STRA, n = 53; control subjects, n = 16) underwent fiberoptic bronchoscopy, bronchoalveolar lavage (BAL), and endobronchial biopsy. Airway inflammation, remodeling, and BAL fluid and biopsy specimen TH2 cytokines were quantified. Children with STRA also underwent symptom assessment (Asthma Control Test), spirometry, exhaled nitric oxide and induced sputum evaluation.
Children with STRA had significantly increased BAL fluid and biopsy specimen eosinophil counts compared with those found in control subjects (BAL fluid, P < .001; biopsy specimen, P < .01); within the STRA group, there was marked between-patient variability in eosinophilia. Submucosal mast cell, neutrophil, and lymphocyte counts were similar in both groups. Reticular basement membrane thickness and airway smooth muscle were increased in patients with STRA compared with those found in control subjects (P < .0001 and P < .001, respectively). There was no increase in BAL fluid IL-4, IL-5, or IL-13 levels in patients with STRA compared with control subjects, and these cytokines were rarely detected in induced sputum. Biopsy IL-5+ and IL-13+ cell counts were also not higher in patients with STRA compared with those seen in control subjects. The subgroup (n = 15) of children with STRA with detectable BAL fluid TH2 cytokines had significantly lower lung function than those with undetectable BAL fluid TH2 cytokines.
STRA in children was characterized by remodeling and variable airway eosinophil counts. However, unlike in adults, there was no neutrophilia, and despite the wide range in eosinophil counts, the TH2 mediators that are thought to drive allergic asthma were mostly absent.
Pediatric asthma; eosinophilia; remodeling; severe therapy-resistant asthma; mediators
Cystic fibrosis (CF) is characterized by bronchoalveolar neutrophilia and submucosal lymphocytosis. We hypothesized that Th17 lymphocytes are part of this submucosal infiltrate.
Quantification and phenotyping of the lymphocytic infiltrate in the bronchial submucosa of patients with CF (n=53, of which 20 were newly diagnosed), non-CF bronchiectasis (n = 17), and healthy control subjects (n = 13).
We measured IL-17 levels in bronchoalveolar lavage and CD4+, CD8+, and IL-17+ cell counts in endobronchial biopsies. Correlations were made with infection status and other inflammatory markers. Potential cellular sources of IL-17 were determined by double staining.
Measurements and Main Results
IL-17+ cell counts (median [interquartile range] cells/mm2) were significantly higher in patients with established CF (205 [115–551]) and non-CF bronchiectasis (245 [183–436]) than in control subjects (53 [12–82]) (P<0.01 for both). Patients with newly diagnosed CF had intermediate counts (171 [91–252]). IL-17–positive CD4+ T cells, γδT cells, natural killer T cells, and neutrophils were identified. Bronchoalveolar lavage IL-17 levels (pg/ml) were highest in established CF (14.6 [2.2–38.4]), low in newly diagnosed CF and control subjects (1.7 [1.7–1.74]; 1.7 [1.7–3]), and intermediate in non-CF bronchiectasis (9.1 [1.7–34] pg/ml) (Kruskal-Wallis P = 0.001). There was a significant correlation between IL-17 and neutrophil counts (P < 0.001, R = 0.6) as well as IL-4 (P < 0.001, R = 0.84).
Th17 lymphocytes are present in the airway submucosa in CF, even in a young, newly diagnosed group. Other IL-17+ cells include neutrophils, γδ T cells, and natural killer T cells.
Th17 cells; cystic fibrosis; inflammation
Asthma frequently commences in early life during airway and immune development and exposure to new environmental challenges. Endobronchial biopsies from children with asthma are abnormal, and lung function is maximally reduced by 6 years of age. As longitudinal biopsy studies are unethical in children, the relationship between development of pathology and reduced lung function is unknown. We aimed to establish a novel neonatal mouse model of allergic airways disease to investigate the developmental sequence of the pathophysiologic features of asthma. Neonatal Balb/c mice were challenged three times weekly from Day 3 of life using intranasal house dust mite (HDM) or saline for up to 12 weeks. Weekly assessments of airway inflammation and remodeling were made. Airway hyperresponsiveness (AHR) to methacholine was assessed from Week 2 onward. Total and eosinophilic inflammation was significantly increased in the lungs of HDM-exposed neonates from Week 2 onwards, and a peak was seen at 3 weeks. Goblet cells and peribronchiolar reticulin deposition were significantly increased in HDM-exposed neonates from Week 3, and peribronchiolar collagen was significantly greater from Week 4. HDM-exposed neonates had increased AHR from Week 2 onward. Although inflammation and AHR had subsided after 4 weeks without allergen challenge, the increased reticulin and collagen deposition persisted in HDM-exposed mice. Neonatal mice exposed to intranasal HDM developed eosinophilic inflammation, airway remodeling, and AHR as reported in pediatric asthma. Importantly, all abnormalities developed in parallel, not sequentially, between 2 and 3 weeks of age.
pediatric; remodeling; asthma pathophysiology; mouse model; allergic airways disease
Primary ciliary dyskinesia (PCD) is usually inherited as an autosomal recessive disorder and presents with upper and lower respiratory tract infection, and mirror image arrangement in around 50% of cases. Cilia dysfunction is also implicated in a wider spectrum of disease, including polycystic liver and kidney disease, central nervous system problems including retinopathy and hydrocephalus, and biliary atresia. Cilia are complex structures, containing more than 250 proteins; recent studies have begun to locate PCD genes scattered throughout the genome. Screening tests for PCD include nasal nitric oxide and in vivo tests of ciliary motility such as the saccharin test. Specific diagnosis requires examination of cilia by light and electron microscopy, with epithelial culture in doubtful cases. This is only available in supra‐regional centres, recently centrally funded by the National Commissioning Group. Treatment is not evidence based and recommendations are largely extrapolated from cystic fibrosis and other suppurative lung diseases.
The relationship between airway structural changes and inflammation is unclear in early cystic fibrosis (CF) lung disease. A study was undertaken to determine changes in airway remodelling in children with CF compared with appropriate disease and healthy controls.
Bronchoalveolar lavage and endobronchial biopsy were performed in a cross‐sectional study of 43 children with CF (aged 0.3–16.8 years), 7 children with primary ciliary dyskinesia (PCD), 26 with chronic respiratory symptoms (CRS) investigated for recurrent infection and/or cough and 7 control children with no lower airway symptoms. Inflammatory cells, cytokines, proteases and matrix constituents were measured in bronchoalveolar lavage fluid (BALF). Reticular basement membrane (RBM) thickness was measured on biopsy specimens using light microscopy.
Increased concentrations of elastin, glycosaminoglycans and collagen were found in BALF from children with CF compared with the CRS group and controls, each correlating positively with age, neutrophil count and proteases (elastase activity and matrix metalloproteinase‐9 (MMP‐9) concentration). There were significant negative correlations between certain of these and pulmonary function (forced expiratory volume in 1 s) in the CF group (elastin: r = −0.45, p<0.05; MMP‐9:TIMP‐1 ratio: r = −0.47, p<0.05). Median RBM thickness was greater in the CF group than in the controls (5.9 μm vs 4.0 μm, p<0.01) and correlated positively with levels of transforming growth factor‐β1 (TGF‐β1; r = 0.53, p = 0.01), although not with other inflammatory markers or pulmonary function.
This study provides evidence for two forms of airway remodelling in children with CF: (1) matrix breakdown, related to inflammation, proteolysis and impaired pulmonary function, and (2) RBM thickening, related to TGF‐β1 concentration but independent of other markers of inflammation.
Single nucleotide polymorphisms (SNPs) in thymic stromal lymphopoietin (TSLP) have been associated with IgE (in girls) and asthma (in general). We sought to determine whether TSLP SNPs are associated with asthma in a sex-specific fashion.
We conducted regular and sex-stratified analyses of association between SNPs in TSLP and asthma in families of asthmatic children in Costa Rica. Significant findings were replicated in white and African-American participants in the Childhood Asthma Management Program, in African Americans in the Genomic Research on Asthma in the African Diaspora study, in whites and Hispanics in the Children’s Health Study, and in whites in the Framingham Heart Study (FHS).
Two SNPs in TSLP (rs1837253 and rs2289276) were significantly associated with a reduced risk of asthma in combined analyses of all cohorts (p values of 2×10−5 and 1×10−5, respectively). In a sex-stratified analysis, the T allele of rs1837253 was significantly associated with a reduced risk of asthma in males only (p= 3×10−6). Alternately, the T allele of rs2289276 was significantly associated with a reduced risk of asthma in females only (p= 2×10−4). Findings for rs2289276 were consistent in all cohorts except the FHS.
TSLP variants are associated with asthma in a sex-specific fashion.
asthma; genetic association; sex-specific; thymic stromal lymphopoietin; TSLP