Asthma: a syndrome composed of heterogeneous diseases

Asthma and Hypogammaglobulinemia: an Asthma Phenotype with Low Type 2 Inflammation

PURPOSE

Little is known about hypogammaglobulinemia (HGG) in asthma patients. No data are available on the characteristics of adult patients with asthma and HGG.

METHODS

We conducted a retrospective monocentric study between January 2006 and December 2012. Asthma patients with a serum immunoglobulin (Ig) quantitative analysis were included and classified into two groups depending on their serum IgG concentration: presence or absence of HGG. Clinical, biological, functional, and radiologic characteristics were compared in univariate and multivariate analysis, using a logistic regression model.

RESULTS

In univariate analysis, asthma patients with HGG (n = 25) were older (58 years old ± 18 vs 49 ± 18, p = 0.04) and more frequently active or former smokers as compared to patients with normoglobulinemia (n = 80) (56.0 vs 35.0 %, p = 0.01). Total IgE < 30 kUI/L was more frequently observed in patients with HGG (53.0 vs 18.3 %, p = 0.01). HGG asthma patients had lower fraction of exhaled nitric oxide (p = 0.02), blood eosinophilia (p = 0.0009), and presented with more severe composite score for bronchiectasis (p = 0.01). In multivariate analysis, asthma patients with HGG had increased risk of being smokers [OR = 6.11 (IC 95 % = 1.16-32.04)], having total IgE concentration < 30 kUI/L [OR = 12.87 (IC 95 % = 2.30-72.15)], and a more severe composite score of bronchiectasis [OR = 20.65 (IC 95 % = 2.13-199.74)].

CONCLUSION

Asthma patients with HGG are older and more often tobacco smoker than asthma patients without HGG. These patients have low type-2 inflammation markers.

The effects of a CXCR1/CXCR2 antagonist on neutrophil migration in mild atopic asthmatic subjects

BACKGROUND

Neutrophils are effector cells recruited to airways in patients with asthma. Migration of neutrophils occurs predominantly through activation of the CXCR1 and CXCR2 receptors by CXC chemokines, including IL-8 and Gro-α. The dual CXCR1/CXCR2 antagonist SCH 527123 has been developed to target neutrophil migration to alleviate airway neutrophilia. This study investigated the effects of SCH 527123 on neutrophil levels within the bone marrow, peripheral blood and airways, and on isolated bone marrow and peripheral blood neutrophil migration from mild allergic asthmatics.

METHODS

Thirteen subjects with mild allergic asthma completed a double blind, placebo-controlled, multi-center crossover study and were randomized to daily dosing of 30 mg SCH 527123 and placebo for 8 days. Subjects provided bone marrow, peripheral blood and sputum samples pre-dosing and on the last day of dosing. Neutrophil numbers were quantified in all samples and chemotaxis assays were performed on neutrophils purified from bone marrow and peripheral blood.

RESULTS

Neutrophil numbers fell significantly in the peripheral blood and sputum following treatment with SCH 527123 compared to placebo treatment. No change in neutrophil numbers was observed in bone marrow. SCH 527123 reduced IL-8-induced migration of purified peripheral blood neutrophils (p < 0.05), but had limited effects on migration of neutrophils purified from bone marrow.

CONCLUSIONS

The results from this study demonstrate that oral administration of the dual CXCR1/CXCR2 antagonist SCH 527123 reduces neutrophil levels in the circulation and airways through inhibition of migration. There were no toxic effects of SCH 527123 on granulocytic progenitor cells in the bone marrow.

Asthma phenotypes: the intriguing selective intervention with Montelukast

Asthma is a heterogeneous disease, usually characterized by chronic airway inflammation and a variable course associated with various underlying mechanisms that can differ between individuals. Patients with asthma can therefore exhibit different phenotypes, a term used to define the observable characteristics of an organism resulting from the interaction between its genetic makeup and the environment. The heterogeneity of asthma has received a large amount of attention in the last few years in order to better tailor treatment according to the different clinical and biological phenotypes of the disease. Specific asthma phenotypes may require an approach to treatment sometimes different from that recommended by current guidelines, so a personalized approach to asthma pharmacotherapy is recommended. Growing evidence suggests that leukotrienes play an important role in the pathogenesis of bronchial asthma. The mechanisms of action of leukotriene-receptor antagonists theoretically predict a good response in some asthma “phenotypes”.In this article we have performed an analysis of the recent literature (controlled clinical trials and real-life studies) about a possible selective intervention with Montelukast in specific asthma phenotypes.

What are the characteristics of asthma patients with elevated serum IgG4 levels?

INTRODUCTION

IgG4 has recently been a subject of great interest in human pathology. No data are available about the characteristics of asthma patients with elevated IgG4 levels.

POPULATION AND METHODS

An observational study was conducted from January 2006 to March 2015 in a difficult-to-treat population of asthma patients. Twenty-six difficult-to-treat asthma patients with elevated serum IgG4 levels (IgG4/IgG ratio up to 10%) were compared with a control population of 98 difficult-to-treat asthma patients with normal serum IgG4. Blood eosinophilia, total IgE and FeNO were compared between groups to better characterize asthma patients with elevated serum IgG4 levels.

RESULTS

Median IgG4 concentrations were 1.72 g/l [1.19-2.36] and 0.22 g/l [0.10-0.49] in the elevated IgG4 group and normal Ig4 group, respectively. Median blood eosinophilia was more than three times higher in patients with elevated serum IgG4 levels than in controls (0.75 10(9)/L [IQR 0.54-1.78] vs 0.22 10(9)/L [IQR 0.09-0.54] respectively, p < 0.0001). Total IgE was twice as high (264.5 kUI/l [IQR 166.3-779] vs 126 kUI/l [IQR 26-350] respectively; p < 0.05) and FeNO was nearly twice as high (61 [IQR 41-111] ppb vs 35 [IQR 23-51] ppb, p < 0.001). Allergic broncho-pulmonary aspergillosis (ABPA) and eosinophilic granulomatosis with polyangiitis (EGPA) were observed in the asthma patients with elevated serum IgG4. Ten patients had unexplained increased blood eosinophilia.

CONCLUSION

Asthma patients with elevated IgG4 levels have significantly higher blood eosinophilia, total IgE and FeNO. ABPA and EGPA are observed in patients with elevated serum IgG4.

IL-17A Autoantibody Induced by Recombinant Mycobacterium smegmatis Expressing Ag85A-IL-17A Fusion Protein

Interleukin-17A is a newly described proinflammatory cytokine, which plays important roles in autoimmune diseases as well as asthma. In current work, we constructed a recombinant plasmid pMFA42S-Ag85a-IL-17a by inserting fusion gene Ag85a-IL-17a into shuttle vector pMFA42S, which was transformed to Mycobacterium smegmatis by electroporation to obtain recombinant M. smegmatis named rMS-Ag85a-IL-17a. The comparison of growth pattern between M. smegmatis and rMS-Ag85a-IL-17a suggested fusion gene had no significant influence on the growth of strains, and rMS-Ag85a-IL-17a expressed fusion protein Ag85A-IL-17A which had good immunogenicity revealed by Western blot. M. smegmatis and rMS-Ag85a-IL-17a were performed to intranasally immunize mice; then, antibody response in sera was detected by enzyme-linked immunosorbent assay. Our findings demonstrated that rMS-Ag85a-IL-17a could induce specific IL-17A autoantibody in mice, which laid the foundation for further study.

Risk of psoriasis in patients with childhood asthma: a Danish nationwide cohort study

BACKGROUND

Psoriasis and asthma are disorders driven by inflammation. Psoriasis may carry an increased risk of asthma, but the reverse relationship has not been investigated.

OBJECTIVES

To investigate the risk of psoriasis in subjects with childhood asthma in a nationwide Danish cohort.

METHODS

Data on all Danish individuals aged 6-14 years at study entry between 1 January 1997 and 31 December 2011 (n = 1,478,110) were linked at an individual level in nationwide registers. Incidence rates per 10,000 person-years were calculated, and incidence rate ratios (IRRs) adjusted for age, sex, concomitant medication and comorbidity were estimated by Poisson regression models.

RESULTS

There were 21,725 cases of childhood asthma and 6586 incident cases of psoriasis. There were 5697 and 889 incident cases of mild and severe psoriasis, respectively. The incidence rates of overall, mild and severe psoriasis were 4.49, 3.88 and 0.61 for the reference population, and 5.95, 5.18 and 0.83 for subjects with childhood asthma, respectively. The IRRs for overall, mild and severe psoriasis were 3.94 [95% confidence interval (CI) 2.16-7.17], 5.03 (95% CI 2.48-10.21) and 2.27 (95% CI 0.61-8.42) for patients with childhood asthma.

CONCLUSIONS

Childhood asthma was associated with a significantly increased risk of psoriasis. Further studies are warranted to determine the clinical significance and effects of therapeutic interventions on this association.

The diversity of young adult wheeze: a cluster analysis in a longitudinal birth cohort

BACKGROUND

Cluster analyses have enhanced understanding of the heterogeneity of both paediatric and adult wheezing. However, while adolescence represents an important transitional phase, the nature of young adult wheeze has yet to be clearly characterised.

OBJECTIVES

To use cluster analysis to define, for the first time, clinically relevant young adult wheeze clusters in a longitudinal birth cohort.

METHODS

K-means cluster analysis was undertaken among 309 currently wheezing subjects at 18 years in the Isle of Wight birth cohort (N = 1456). Thirteen disease-characterising clustering variables at 18 years were used. Resulting clusters were then further characterised by severity indices plus potential risk factors for wheeze development throughout the 1st 18 years of life.

RESULTS

Six wheeze clusters were identified. Cluster 1 (12.3%) male-early-childhood-onset-atopic-wheeze-with-normal-lung-function had male predominance, normal spirometry, low bronchodilator reversibility (BDR), intermediate bronchial hyper-responsiveness (BHR), high atopy prevalence and more admissions. Cluster 2 (24.2%) early-childhood-onset-wheeze-with-intermediate-lung-function had no specific sex association, intermediate spirometry, BDR, BHR, more significant BTS step therapy and admissions. Cluster 3 (9.7%) female-early-childhood-onset-atopic-wheeze-with-impaired-lung-function showed female predominance, high allergic disease comorbidity, more severe BDR and BHR, greatest airflow obstruction, high smoking prevalence, higher symptom severity and admissions. Cluster 4 (19.4%) female-undiagnosed-wheezers had adolescent-onset non-atopic wheeze, low BDR and BHR, impaired but non-obstructed spirometry, high symptom frequency and highest smoking prevalence. Cluster 5 (24.6%) female-late-childhood-onset-wheeze-with-normal-lung-function showed no specific atopy association, normal spirometry, low BDR, BHR and symptom severity. Cluster 6 (9.7%) male-late-childhood-onset-atopic-wheeze-with-impaired-lung-function had high atopy and rhinitis prevalence, increased BDR and BHR, moderately impaired spirometry, high symptom severity and higher BTS step therapy.

CONCLUSIONS AND CLINICAL RELEVANCE

Young adult wheeze is diverse and can be classified into distinct clusters. More severe clusters merit attention and are associated with childhood onset, atopy, impaired lung function and in some, smoking. Smoking-associated undiagnosed wheezers also merit recognition. Better understanding of young adult wheeze could facilitate better later adult respiratory health.

Frequent cough in unsatisfactory controlled asthma--results from the population-based West Sweden Asthma study

BACKGROUND

Asthma is a complex disease presenting with variable symptoms which are sometimes hard to control. The purpose of the study was to describe the prevalence of asthma symptoms, use of asthma medications and allergic sensitization in subjects with asthma. We also related those indices to the level of asthma control, lung function and in particular, cough.

METHODS

An extensive questionnaire was sent to randomly selected adults from the West Sweden region. Clinical examinations and interview were performed in a subset. Of the participants, 744 were defined as having an ongoing asthma - reported ever having asthma or physician diagnosed asthma and one of the following - use of asthma medications, recurrent wheeze or attacks of shortness of breath with or without wheeze in the last 12 months. A respiratory disease-free control group of 847 subjects was also described.

RESULTS

According to GINA guidelines, 40.6% of the asthmatics had partly controlled and 17.8% had uncontrolled asthma. Asthmatic subjects reported significantly more symptoms in the last 12 months than the control group - wheezing (79.4 vs 9.2%), shortness of breath (36.1 vs 2.5%), wheezing with shortness of breath (58.7 vs 1.3%). Important complaints were morning cough (42.5 vs 15.5%), cough with sputum production (36.1 vs 6.8%) and longstanding cough (32.5 vs 11.1%), which bothered two thirds of the uncontrolled and one third of partly controlled subjects. Asthma medications were used by 87.5% of the asthmatics, although around 30% of them who had insufficiently controlled disease used only short-acting beta-agonists. Asthmatics also had lower lung function, reacted to lower doses of methacholine that the controls and 13.6% of them had a FEV1/FVC ratio below 0.7. Allergic rhinitis was reported by 73.8% of the asthmatics and they were more frequently sensitized to several common allergens.

CONCLUSIONS

Approximately 60% of asthmatics from this population-based study had insufficiently controlled asthma and persistent complaints, despite a high use of asthma medications. These self-reported symptoms were supported by clinical examination data. Increased cough frequency is an indicator of a more severe and difficult to control disease and should be considered when asthma is characterized.

Is asthma an infectious disease? New evidence

The pathogenetic mechanisms leading to asthma are likely to be diverse, influenced by multiple genetic polymorphisms as well as elements of the environment. Recent data on the microbiome of the airway have revealed intriguing differences between the number and diversity of microbial populations in healthy persons and asthmatics. There is convincing evidence that early viral infections, particularly with human rhinovirus and respiratory syncytial virus, are often associated with the development of chronic asthma and with exacerbations. Recent studies suggest that two unrelated types of atypical bacteria, Mycoplasma pneumoniae (Mpn) and Chlamydia pneumoniae, are present in the airways of a substantial proportion of the population, bringing up the possibility that the persistent presence of the organism may contribute to the asthmatic phenotype in a subset of patients. This review will examine the current data regarding a possible role for infection in chronic asthma with a particular focus on atypical bacterial infections.

Bronchial smooth muscle cells of asthmatics promote angiogenesis through elevated secretion of CXC-chemokines (ENA-78, GRO-α, and IL-8)

Background

Airway wall remodelling is a key pathology of asthma. It includes thickening of the airway wall, hypertrophy and hyperplasia of bronchial smooth muscle cells (BSMC), as well as an increased vascularity of the sub-epithelial cell layer. BSMC are known to be the effector cells of bronchoconstriction, but they are increasingly recognized as an important source of inflammatory mediators and angiogenic factors.

Objective

To compare the angiogenic potential of BSMC of asthmatic and non-asthmatic patients and to identify asthma-specific angiogenic factors.

Methods

Primary BSMC were isolated from human airway tissue of asthmatic and non-asthmatic patients. Conditioned medium (CM) collected from BSMC isolates was tested for angiogenic capacity using the endothelial cell (EC)-spheroid invitro angiogenesis assay. Angiogenic factors in CM were quantified using a human angiogenesis antibody array and enzyme linked immunosorbent assay.

Results

Induction of sprout outgrowth from EC-spheroids by CM of BSMC obtained from asthma patients was increased compared with CM of control BSMC (twofold, p < 0.001). Levels of ENA-78, GRO-α and IL-8 were significantly elevated in CM of BSMC from asthma patients (p < 0.05 vs. non-asthmatic patients). SB 265610, a competitive antagonist of chemokine (CXC-motif) receptor 2 (CXCR2), attenuated the increased sprout outgrowth induced by CM of asthma patient-derived BSMC.

Conclusions

BSMC isolated from asthma patients exhibit increased angiogenic potential. This effect is mediated through the CXCR2 ligands (ENA78, GRO-α and IL-8) produced by BSMC.

Implications

CXCR2 ligands may play a decisive role in directing the neovascularization in the sub-epithelial cell layers of the lungs of asthma patients. Counteracting the CXCR2-mediated neovascularization by pharmaceutical compounds may represent a novel strategy to reduce airway remodelling in asthma.

Factors influencing the response to specific immunotherapy for asthma in children aged 5-16 years

BACKGROUND

The aim of this study was to evaluate the factors predicting the response to allergen-specific immunotherapy (ASIT) in children with asthma.

METHODS

The case notes of children with asthma who received ASIT for 2 years were retrospectively reviewed. The cases were then divided into an effective clinical response group, defined as absence of asthma symptoms without requirement for medication for at least 6 months during follow up; and an ineffective clinical response group. At the time of initiating treatment, blood was collected for analysis of serum total IgE. Family history of atopy, history of passive smoking, onset age of wheezing and so on was obtained from each patient. Ten factors that may influence children's response were analyzed on logistic regression analysis and compared between groups.

RESULTS

A total of 99 children with asthma received ASIT s.c. for 2 years during September 2007-February 2010. The average age was 8.66 ± 0.30 years. Good response to ASIT was found in 72 cases, while an inadequate response was found in 27 cases. Of the 10 factors tested for correlation with clinical response to ASIT, a significant correlation was found with onset age of wheezing and airway hyperresponsiveness (AHR). The odds ratio for the onset age of wheezing was 2.81 (95% confidence interval [CI]: 1.40-5.65, P = 0.004) and that for AHR was 1.33 (95%CI: 1.04-1.70, P = 0.021).

CONCLUSION

Potential predictors for the response to ASIT in children with asthma were identified. Onset age of wheezing and AHR may influence response to ASIT.

Th17-mediated inflammation in asthma

Asthma is a heterogeneous disease with many different phenotypes. Moderate and severe asthma phenotypes have been associated with increased neutrophils and increased Th17 cytokines, IL-17A, IL-17F, and IL-22, in the bronchoalveolar lavage fluid of patients. Th17 cytokines recruit neutrophils to the airway by increasing secretion of epithelial-derived neutrophilic chemokines. In addition, Th17 cytokines also induce mucous cell metaplasia and have pleotropic effects on airway smooth muscle resulting in airway narrowing. The role of Th17 cytokines in regulating Th2 cytokine expression and allergic airway inflammation remains unclear with conflicting reports. However, the role of Th17 cells in asthma will be answered in ongoing clinical trials with therapeutics targeting IL-17A and IL-17 receptor signaling.

Genetic variation in Ameloblastin is associated with caries in asthmatic children

AIM

Evidence suggests caries experience is higher in children with asthma. This study compared caries experience in asthmatic and non-asthmatic children and defined whether variation in the distribution of caries experience differed between the two groups and was dependent on the presence of genetic variation in enamel formation genes.

METHODS

Children with asthma were recruited at the Istanbul University, Faculty of Medicine, Department of Paediatrics, Division of Paediatric Allergy and Pulmonary Diseases, and non-affected children were recruited at the Istanbul University, Faculty of Dentistry, Department of Paedodontics. Cases (N = 100) were defined as children between the ages of 6 and 12 years with asthma and controls (N = 100) as children without asthma. Cases and controls were matched by sex and age. All study subjects received a complete dental exam, provided demographic and other caries and asthma risk factors data, and a saliva sample for DNA extraction. Caries experience was defined based on DMFT/dmft and DMFS/dmfs scores. Genotypes of 11 SNPs were selected in intronic regions of enamel development genes. PCR with TaqMan chemistry was used for genotyping all selected markers. Association between caries experience (caries-free versus caries affected) depending on asthma status and SNPs was tested with PLINK by logistic regression, adjusting by risk, and other preventive measures. p values below 0.0045 (0.05/11) were considered statistically significant.

RESULTS

Logistic regression analysis showed an association between AMBN rs4694075 and caries experience (p = 2.525e-007).

CONCLUSIONS

This study provides, for the first time, evidence that ameloblastin is associated with caries in asthmatic children.

Genomic and systems approaches to translational biomarker discovery in immunological diseases

The high failure rate of new therapeutic mechanisms tested in clinical development has spurred an upsurge in research dedicated to discovering biomarker readouts that can improve decision-making. Increasingly, systems biology and genomic technologies, such as transcriptional profiling, are being leveraged to aid in the discovery of biomarker readouts. For inflammatory and immunological diseases, such as rheumatoid arthritis (RA) and asthma, progress has been made in developing biomarkers to monitor disease activity, prediction of response to therapy, and pharmacodynamic (PD) measurements. In this review, we discuss recent successes and challenges in these endeavors, highlighting the importance of human clinical studies of standard-of-care treatments in control subjects and patients with disease as the most direct path toward identifying useful translational biomarkers for clinical development.

Clinical asthma phenotypes and therapeutic responses

Asthma is a heterogeneous disease that means not all asthmatics respond to the same treatment. We hypothesize an approach to characterize asthma phenotypes based on symptomatology (shortness of breath (SOB), cough, and wheezy phenotypes) in correlation with airway inflammatory biomarkers and FEV1. We aimed to detect whether those clinical phenotypes have an impact on the response to asthma medications. Two hundred three asthmatic children were allocated randomly to receive either montelukast (5 mg at bed time) or fluticasone propionate (100 ug twice daily) for 8 consecutive weeks. Serum concentrations of IL-2Rs, ICAM-1, VCAM-1, total IgE, eosinophilic %, eosinophil cationic protein (ECP), and FEV1 were done before and after treatment to patients and once to controls. Children who have SOB were found to have higher levels of total sIgE, older age, and longer disease duration, and they responded to fluticasone alone. Cough group was found to have higher levels of eosinophilic % and sECP, younger age, shorter disease duration and responded to montelukast alone. Wheezy group showed mixed pattern and responded to both medications. Conclusion. Although there is variability in response to ICS and LTRAs, we did identify characteristics of patient that should guide the clinician in the choice of asthma medications.

Serum 25-hydroxyvitamin D levels and incident asthma in adults: the HUNT Study

The impact of low vitamin D status on asthma development is unclear. The authors investigated the relation between the baseline serum 25-hydroxyvitamin D (25(OH)D) level and incident asthma in adults, including possible effect modification by allergy status, using allergic rhinitis as a proxy measure. A cohort of 25,616 Norwegian adults aged 19-55 years participated in 2 surveys of the Nord-Trøndelag Health Study known as HUNT 2 (1995-1997) and HUNT 3 (2006-2008). Of this cohort, a nested case-control study included 584 new-onset asthma cases and 1,958 nonasthma controls whose baseline serum 25(OH)D levels were measured. After adjustment for potential asthma risk factors, the baseline serum level of 25(OH)D (<50 nmol/L) was not significantly associated with asthma in either women (adjusted odds ratio = 0.94, 95% confidence interval (CI): 0.67, 1.32) or men (adjusted odds ratio = 1.47, 95% CI: 0.93, 2.32). In men, allergic rhinitis modified the association with the adjusted odds ratio being 0.87 (95% CI: 0.36, 2.06) among men with allergic rhinitis and 2.32 (95% CI: 1.06, 5.10) among men without allergic rhinitis. The serum 25(OH)D level was not associated with incident asthma in women, regardless of allergy status. Low vitamin D status was not significantly associated with incident asthma in most adults, but it may have increased risk among men without allergy.

Genome-wide association studies of asthma in population-based cohorts confirm known and suggested loci and identify an additional association near HLA

RATIONALE

Asthma has substantial morbidity and mortality and a strong genetic component, but identification of genetic risk factors is limited by availability of suitable studies.

OBJECTIVES

To test if population-based cohorts with self-reported physician-diagnosed asthma and genome-wide association (GWA) data could be used to validate known associations with asthma and identify novel associations.

METHODS

The APCAT (Analysis in Population-based Cohorts of Asthma Traits) consortium consists of 1,716 individuals with asthma and 16,888 healthy controls from six European-descent population-based cohorts. We examined associations in APCAT of thirteen variants previously reported as genome-wide significant (P<5 x 10(-8)) and three variants reported as suggestive (P<5× 10(-7)). We also searched for novel associations in APCAT (Stage 1) and followed-up the most promising variants in 4,035 asthmatics and 11,251 healthy controls (Stage 2). Finally, we conducted the first genome-wide screen for interactions with smoking or hay fever.

MAIN RESULTS

We observed association in the same direction for all thirteen previously reported variants and nominally replicated ten of them. One variant that was previously suggestive, rs11071559 in RORA, now reaches genome-wide significance when combined with our data (P = 2.4 × 10(-9)). We also identified two genome-wide significant associations: rs13408661 near IL1RL1/IL18R1 (P(Stage1+Stage2) = 1.1x10(-9)), which is correlated with a variant recently shown to be associated with asthma (rs3771180), and rs9268516 in the HLA region (P(Stage1+Stage2) = 1.1x10(-8)), which appears to be independent of previously reported associations in this locus. Finally, we found no strong evidence for gene-environment interactions with smoking or hay fever status.

CONCLUSIONS

Population-based cohorts with simple asthma phenotypes represent a valuable and largely untapped resource for genetic studies of asthma.

How to diagnose and phenotype asthma

Asthma has been described as a chronic disease of the airways characterized by variable airflow obstruction, airway hyperresponsiveness, and airway inflammation. This review discusses the diagnosis and phenotyping of asthma, with a special emphasis on phenotyping based on the nature of cellular inflammation and radiological imaging and how this could be used to direct the treatment of asthma and, in the future, to apply specifically directed therapies to specific phenotypes.

The regulation of fibrosis in airway remodeling in asthma

Fibrosis is one of the key pathological features of airway remodeling in asthma. In the normal airway the amount of collagen and other extracellular matrix components is kept in equilibrium by regulation of synthesis and degradation. In asthma this homeostasis is disrupted due to genetic and environmental factors. In the airways of patients with the disease there is increased extracellular matrix deposition, particularly in the reticular basement membrane region, lamina propria and submucosa. Fibrosis is important as it can occur early in the pathogenesis of asthma, be associated with severity and resistant to therapy. In this review we will discuss current knowledge of relaxin and other key regulators of fibrosis in the airway including TGFβ, Smad2/3 and matrix metalloproteinases. As fibrosis is not directly targeted or effectively treated by current asthma drugs including corticosteroids, characterization of airway fibrosis and how it is regulated will be essential for the development of novel therapies for asthma.

Drug repositioning for personalized medicine

Human diseases can be caused by complex mechanisms involving aberrations in numerous proteins and pathways. With recent advances in genomics, elucidating the molecular basis of disease on a personalized level has become an attainable goal. In many cases, relevant molecular targets will be identified for which approved drugs already exist, and the potential repositioning of these drugs to a new indication can be investigated. Repositioning is an accelerated route for drug discovery because existing drugs have established clinical and pharmacokinetic data. Personalized medicine and repositioning both aim to improve the productivity of current drug discovery pipelines, which expend enormous time and cost to develop new drugs, only to have them fail in clinical trials because of lack of efficacy or toxicity. Here, we discuss the current state of research in these two fields, focusing on recent large-scale efforts to systematically find repositioning candidates and elucidate individual disease mechanisms in cancer. We also discuss scenarios in which personalized drug repositioning could be particularly rewarding, such as for diseases that are rare or have specific mutations, as well as current challenges in this field. With an increasing number of drugs being approved for rare cancer subtypes, personalized medicine and repositioning approaches are poised to significantly alter the way we diagnose diseases, infer treatments and develop new drugs.

Exposure to particulate hexavalent chromium exacerbates allergic asthma pathology

Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels.

Mitochondrial genetic background plays a role in increasing risk to asthma

A number of studies suggest that mitochondrial dysfunction plays a role in the pathogenesis of asthma. To shed light for the first time on the role of the mitochondrial genome in the etiology of asthma we analyzed the mitochondrial tRNA genes and part of their flanking regions in patients with asthma compared with a set of healthy controls. We found a total of 10 mutations in 56 out of 76 asthmatic patients. Four of these mutations were not found in the control group, five were observed at a significantly lower frequency in controls, but none of the combinations of mutations detected in asthma patients was observed in the controls. Furthermore, we observed that 27.6% of the asthma patients (vs. 4% of the controls) belonged to the haplogroup U (Fisher test P = 0.00) and a positive significant correlation was found between the occurrence of the haplogroup U and the severity of the disease (Fisher test P = 0.02). Whereas further studies in larger cohorts are needed to confirm these observations we suggest that the mitochondrial genetic background plays a key role in asthma development.

Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma

BACKGROUND

We previously found a significant benefit of vitamin C supplementation in asthmatic children.

PURPOSE

To test whether the effect of vitamin C on asthma is heterogeneous over the participant population.

METHODS

Egyptian asthmatic children between 7 and 10 years of age (n = 60) were included in the cross-over trial. They were administered 0.2 grams per day of vitamin C and placebo for separate 6-week periods. The variation in the vitamin C effect on two clinically relevant outcomes was analyzed: the childhood asthma control test (C-ACT), which measures the severity of asthma symptoms (the scale ranges from 0 to 27 points, < 20 points indicating unsatisfactory asthma control), and FEV1. We used linear modeling to examine the variation of the vitamin C effect in the subgroups.

RESULTS

The effect of vitamin C on the C-ACT was significantly modified by age and baseline C-ACT levels. In the children aged 7.0-8.2 years with a baseline C-ACT of 18 to 19 points, vitamin C increased the C-ACT score by 4.2 points (95% CI: 3.3-5.3); whereas in the children aged 8.3-10 years who had a baseline C-ACT of 14 to 15 points, vitamin C increased the C-ACT score by only 1.3 points (95% CI: 0.1-2.5). The effect of vitamin C on the FEV1 levels was significantly modified by age and exposure to dampness. In the children aged 7.0-8.2 years with no exposure to dampness, vitamin C increased the FEV1 level by 37% (95% CI: 34-40%), whereas in the children aged 8.3-10 years with exposure to dampness or mold in their bedroom more than one year prior to the study, vitamin C increased the FEV1 level by only 21% (95% CI: 18-25%).

CONCLUSIONS

We found strong evidence that the effect of vitamin C on asthmatic children is heterogeneous. Further research is needed to confirm our findings and identify the groups of children who would receive the greatest benefit from vitamin C supplementation.

Airway platelet activation is associated with airway eosinophilic inflammation in asthma

BACKGROUND

Allergic asthma is characterized by airway inflammation associated with recruitment and activation of eosinophils. In mice, allergen exposure induces platelet migration to the airways that is necessary for eosinophil recruitment and activation. We therefore hypothesized that in the airways of human subjects with asthma, platelet activation would be positively associated with eosinophil activation and platelet and eosinophil activation would both be associated with clinical asthma characteristics.

METHODS

Nasal wash levels of P-selectin (a measure of platelet activation) and eosinophil cationic protein (ECP) (a measure of eosinophil activation) were compared with each other and with clinical asthma characteristics in a cross-sectional study of urban children and adolescents (age range, 6-20 years) with asthma.

RESULTS

Regression analysis revealed a significantly positive association between log10 P-selectin levels and log10 ECP levels (β = 0.50 ng/mL [95% confidence interval, 0.05-0.94 ng/mL]; P = 0.029). Additionally, ECP was significantly and negatively associated with 2 asthma-related quality of life measurements, and P-selectin was associated with one of these.

CONCLUSIONS

Our study shows the first significant association between platelet and eosinophil activation in airways of human subjects with asthma. These data provide a first step toward delineating what seems to be an important role for platelets in airway eosinophilia.

Risk factors for current wheezing and its phenotypes among elementary school children

BACKGROUND

Accumulating evidence suggests, asthma includes many phenotypes with varying clinical and prognostic features. Epidemiological surveys documented a number of environmental risk factors for the development of asthma and interestingly these differ between and within countries, suggesting that the differences may be related with the different distribution of asthma phenotypes. This study aimed to investigate risk factors of current wheezing (CW) and different wheezing phenotypes in elementary school children.

METHODS

Six thousand nine hundred sixty-three 9- to 11-year-old children of a previous multicenter survey where the methodology of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase-II was used were analyzed. Wheezing phenotypes were defined as wheezing with rhinitis (RW), wheezing with rhinoconjunctivitis (RCW), atopic wheezing (AW), non-atopic wheezing (NAW), and frequent wheezing (FW) (≥4/year wheezing episodes).

RESULTS

The prevalence of CW was 15.8% and among these, 22.4%, 67.3%, 45.9%, 20.5%, and 79.5% were classified as FW, RW, RCW, AW, and NAW, respectively. History of parental asthma/allergic rhinitis, coexistence of other allergic diseases, presence of mold and dampness in the house lived during the first year of life and maternal smoking in pregnancy were found to be risk factors for most phenotypes (odds ratio (OR) ranged from 1.43 to 3.56). Number of household in the last year (OR = 1.14), prematurity (OR = 2.08), and duration of breastfeeding (OR = 1.02) per additional month were found to be risk factor for FW, AW, and RCW, respectively.

CONCLUSION

Beside common risk factors for the development of asthma and its phenotypes, certain risk factors appeared to play a role in the development of phenotypic characteristics of asthma. These findings support our hypothesis that each phenotype has not only different clinical characteristics but also has different roots.

Overcoming heterogeneity in pediatric asthma: tobacco smoke and asthma characteristics within phenotypic clusters in an African American cohort

OBJECTIVE

Asthma in children and adolescents is a heterogeneous syndrome comprised of multiple subgroups with variable disease expression and response to environmental exposures. The goal of this study was to define homogeneous phenotypic clusters within a cohort of children and adolescents with asthma and to determine overall and within-cluster associations between environmental tobacco smoke (ETS) exposure and asthma characteristics.

METHODS

A combined hierarchical/k-means cluster analysis of principal component variables was used to define phenotypic clusters within a cohort of 6- to 20-year-old urban and largely minority subjects.

RESULTS

Among the 154 subjects, phenotypic cluster analysis defined three independent clusters (Cluster 1 [n = 57]; Cluster 2 [n = 33]; Cluster 3 [n = 58]). A small fourth cluster (n = 6) was excluded. Patients in Cluster 1 were predominantly males, with a relative abundance of neutrophils in their nasal washes. Patients in Cluster 2 were predominantly females with high body mass index percentiles and later-onset asthma. Patients in Cluster 3 had higher eosinophil counts in their nasal washes and lower Asthma Control Test (ACT) scores. Within-cluster regression analysis revealed several significant associations between ETS exposure and phenotypic characteristics that were not present in the overall cohort. ETS exposure was associated with a significant increase in nasal wash neutrophils (beta coefficient = 0.73 [95% confidence interval, CI: 0.11 to 1.35]; p = .023) and a significant decrease in ACT score (-5.17 [-8.42 to -1.93]; p = .003) within Cluster 1 and a significant reduction in the bronchodilator-induced % change in forced expiratory volume in one second (FEV(1)) (-36.32 [-62.18 to -10.46]; p = .009) within Cluster 3.

CONCLUSIONS

Clustering techniques defined more homogeneous subgroups, allowing for the detection of otherwise undetectable associations between environmental tobacco smoke exposure and asthma characteristics.

Eosinophils are dispensable for allergic remodeling and immunity in a model of house dust mite-induced airway disease

RATIONALE

Current thinking accredits eosinophils with preeminent contributions to allergic airway responses, including a major role in the development of airway remodeling, a process thought to significantly contribute to airway dysfunction. However, direct evidence in support of this notion is limited and often controversial.

OBJECTIVES

We elucidated the requirement for eosinophils in the generation of allergic sensitization, airway inflammation, and remodeling in a model involving chronic respiratory exposure to house dust mite (HDM).

METHODS

We used three methods to selectively eliminate eosinophils, a depleting antibody (anti-CCR3), and two strains of eosinophil-deficient mice (ΔdblGATA and the transgenic line PHIL).

MEASUREMENTS AND MAIN RESULTS

Anti-CCR3 treatment markedly reduced pulmonary eosinophilia (> 80%) over the course of HDM exposure but had no effect on the remaining inflammatory response, the extent of lung Th2 cells, or the development of remodeling-associated changes, including subepithelial collagen deposition and smooth muscle thickening. In addition, we observed that, despite the absence of eosinophils, HDM-exposed GATA mice mounted robust airway and lung inflammation and hyperresponsiveness and showed a remodeling response equivalent to that observed in wild-type mice. Moreover, these mice had similar serum HDM-specific IgE levels and Th2-associated splenocyte cytokine production as HDM-exposed wild-type control mice. Similar observations were made in PHIL eosinophil-deficient mice subjected to chronic HDM exposure, although slight decreases in airway mononuclear cells, but not lung Th2 cells, and remodeling were noted.

CONCLUSIONS

Collectively, these data demonstrate that, at variance with the prevailing paradigm, eosinophils play negligible roles in the generation of HDM-induced allergic immunity and airway remodeling.

Liquid chromatography-tandem mass spectrometry analysis of urinary fluticasone propionate-17beta-carboxylic acid for monitoring compliance with inhaled-fluticasone propionate therapy

BACKGROUND

Inhaled corticosteroids including fluticasone propionate (FP) are the most effective treatment for persistent-asthma. Noncompliance ranging from 20% to 80% of treated patients is associated with substantial health care costs, morbidity and fatalities. A noninvasive test to assess FP treatment compliance is needed. The major metabolite of FP is FP-17beta-carboxylic acid (FP17betaCA) and is excreted in urine. This study demonstrates the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to measure FP17betaCA in urine and evaluation of FP17betaCA urinary elimination.

EXPERIMENTAL

Fluorometholone was used as the internal standard. After acetonitrile precipitation, samples were extracted with dichloromethane, washed and dried. Reconstituted extract (60 microL) was subjected to reversed-phase chromatography and positive-ion mode LC-MS/MS analysis. Assay precision, linearity, recovery and sample stability were determined. Elimination evaluation included measurement of FP17betaCA in urine collected daily from human subjects before (day 1), during treatment (days 2-5; dose FP-110 microg 2 puffs/day), and following cessation of FP therapy (days 6-14; n=4).

RESULTS

Linear range of the FP17betaCA assay was 10.3-9510pg/mL. Limit of quantitation (LOQ) was 10.3 pg/mL and recovery ranged from 85.8% to 111.9%. Inter-assay CVs were 7.4-12.0% for FP17betaCA concentrations of 11.1-5117 pg/mL. Urine FP17betaCA was absent in subjects prior to FP therapy, detectable (180-1991 ng FP17betaCA/g creatinine) throughout the dosing period and reached below the LOQ at 6 days after therapy cessation.

CONCLUSIONS

Measurement of FP17betaCA by LC-MS/MS has acceptable analytical performance for clinical use. These data support the clinical utility of measuring FP17betaCA in urine to monitor patient compliance with FP therapy.

Current guidelines for the management of asthma in young children

The diagnosis and management of asthma in young children is difficult, since there are many different wheezy phenotypes with varying underlying aetiologies and outcomes. This review discusses the different approaches to managing young children with wheezy illnesses presented in recently published global guidelines. Four major guidelines published since 2007 are considered. Helpful approaches are presented to assist the clinician to decide whether a clinical diagnosis of asthma can, or should be made in a young child with a recurrent wheezy illness and which treatments would be appropriate, dependent on risk factors, age of presentation, response to initial treatment and safety considerations. Each of the guidelines provide useful information for clinicians assessing young children with recurrent wheezy illnesses. There are differences in classification of the disease and treatment protocols. Although a firm diagnosis of asthma may only be made retrospectively in some cases and there are several effective guidelines to initiating treatment. Consistent review of the need for ongoing treatment with a particular pharmacological modality is essential, since many children with recurrent wheezing in infancy go into spontaneous remission. It is probable that newer biomarkers of airway inflammation will assist the clinician as to when to initiate and when to continue pharmacological treatment in the future.

Asthma phenotypes

The many roads leading to the syndrome of asthma have proven to be intricately interconnected. The chronic inflammation of asthma is characterized by airway hyperreactivity and variable reversibility. Past classification systems relied on assessment of daily impairment and the distinction between intrinsic (nonallergic) and extrinsic (allergic). With more precise asthma phenotypes, association studies likely will have greater significance. In addition, patients at higher risk for severe disease can be more effectively managed, and treatments can be directed to responders. In this review, we look at eight identified phenotypes: atopic and nonatopic status, pre-asthma wheezing, inflammatory mediator predominance, aspirin-sensitive, exercise-induced, severe, and flare-prone asthma. Although significant overlap exists among the distinctions, any future phenotype classification system will need to incorporate these eight clinical asthmatic populations.

Different inflammatory mechanisms in lungs of severe and mild asthma: crosstalk of NF-kappa-B, TGFbeta1, Bax, Bcl-2, IL-4 and IgE

OBJECTIVE

To examine differences in the apoptotic, inflammatory, allergic and immunological features in the lungs of adults with asthma.

MATERIAL AND METHODS

Thirty-six patients with mild asthma (MA), 16 with severe asthma (SA) and 20 healthy volunteers (HVs) were enrolled. Bronchoalveolar lavage fluid (BALF) was processed into cell-free fluid for enzyme-linked immunosorbent assay detecting soluble TGFbeta1, IL-4 and IgE and BALF lymphocytes for immunocytochemical staining of cellular Bax, Bcl-2 and nuclear factor-Kappa-B (NFkappaB).

RESULTS

Cellular NFkappaB expression was higher in SA than in MA and HVs, while extracellular TGFbeta1 was high in both the SA and MA groups but low in the HVs. Bcl-2/Bax ratio was higher in SA than in MA and in MA than in HV groups and correlated significantly with NFkappaB level. Interestingly, the levels of IgE and, to a lesser extent, IL-4 were higher in MA than in SA and both were much higher than in HVs, and were inversely correlated with NFkappaB level in the SA group and with TGFbeta1 level in the MA group.

CONCLUSIONS

NFkappaB has a central role in the perpetuation of persistent inflammation in SA and might induce apoptosis via Bcl-2. The SA group appears not associated much with allergen-based IgE and IL-4 reactions as efficiently as in MA. This was supported by the lower levels of IgE and IL-4 in SA compared to MA. TGFbeta1 appears to be associated with asthma pathogenesis, especially allergen-based MA.

Total IgE levels and asthma prevalence in the US population: results from the National Health and Nutrition Examination Survey 2005-2006

BACKGROUND

The inability to measure IgE-based sensitivity to all allergens has limited our understanding of what portion of asthma is related to IgE. Total IgE measurement can potentially overcome this limitation.

OBJECTIVE

We sought to determine the association between total IgE levels and asthma.

METHODS

The National Health and Nutrition Examination Survey 2005-2006 examined a representative sample of the US population 6 years of age and older.

RESULTS

The median total IgE level was 40.8 kU/L (interquartile range, 15.5-114 kU/L). Total IgE levels varied with age, sex, race/ethnicity, serum cotinine level, body size, and socioeconomic status. The prevalence of current asthma was 8.8%. The prevalence of atopy was 42.5%, as defined by 15 specific IgEs. The adjusted odds ratio (OR) for asthma with a 10-fold increase in total IgE level was 2.18 (95% CI, 1.66-2.87). Total IgE level predicted asthma only among atopic subjects (OR, 2.41; 95% CI, 1.62-3.60) and not among nonatopic subjects (OR, 1.11; 95% CI, 0.72-1.71; interaction P = .005). Among atopic subjects, the association between total IgE level and asthma became stronger as the number of positive specific IgE test results increased. Asthma was present at even the lowest levels of total IgE, regardless of atopic status. Approximately 92% of atopic subjects were identified by 6 specific IgEs, but to increase the identification to more than 99% required 11 specific IgEs.

CONCLUSION

Total IgE levels are associated with asthma only among persons who have positive results for at least 1 allergen-specific IgE. Asthma independent of IgE is not uncommon in the US population. The complete identification of atopic subjects in a population requires a large panel of allergen-specific IgEs.