An association between L-arginine/asymmetric dimethyl arginine balance, obesity, and the age of asthma onset phenotype

RATIONALE

Increasing body mass index (BMI) has been associated with less fractional exhaled nitric oxide (Fe(NO)). This may be explained by an increase in the concentration of asymmetric dimethyl arginine (ADMA) relative to L-arginine, which can lead to greater nitric oxide synthase uncoupling.

OBJECTIVES

To compare this mechanism across age of asthma onset groups and determine its association with asthma morbidity and lung function.

METHODS

Cross-sectional study of participants from the Severe Asthma Research Program, across early- (<12 yr) and late- (>12 yr) onset asthma phenotypes.

MEASUREMENTS AND MAIN RESULTS

Subjects with late-onset asthma had a higher median plasma ADMA level (0.48 μM, [interquartile range (IQR), 0.35-0.7] compared with early onset, 0.37 μM [IQR, 0.29-0.59], P = 0.01) and lower median plasma l-arginine (late onset, 52.3 [IQR, 43-61] compared with early onset, 51 μM [IQR 39-66]; P = 0.02). The log of plasma L-arginine/ADMA was inversely correlated with BMI in the late- (r = -0.4, P = 0.0006) in contrast to the early-onset phenotype (r = -0.2, P = 0.07). Although Fe(NO) was inversely associated with BMI in the late-onset phenotype (P = 0.02), the relationship was lost after adjusting for L-arginine/ADMA. Also in this phenotype, a reduced L-arginine/ADMA was associated with less IgE, increased respiratory symptoms, lower lung volumes, and worse asthma quality of life.

CONCLUSIONS

In late-onset asthma phenotype, plasma ratios of L-arginine to ADMA may explain the inverse relationship of BMI to Fe(NO). In addition, these lower L-arginine/ADMA ratios are associated with reduced lung function and increased respiratory symptom frequency, suggesting a role in the pathobiology of the late-onset phenotype.

P2X7-regulated protection from exacerbations and loss of control is independent of asthma maintenance therapy

RATIONALE

The function of the P2X(7) nucleotide receptor protects against exacerbation in people with mild-intermittent asthma during viral illnesses, but the impact of disease severity and maintenance therapy has not been studied.

OBJECTIVES

To evaluate the association between P2X(7), asthma exacerbations, and incomplete symptom control in a more diverse population.

METHODS

A matched P2RX7 genetic case-control was performed with samples from Asthma Clinical Research Network trial participants enrolled before July 2006, and P2X(7) pore activity was determined in whole blood samples as an ancillary study to two trials completed subsequently.

MEASUREMENTS AND MAIN RESULTS

A total of 187 exacerbations were studied in 742 subjects, and the change in asthma symptom burden was studied in an additional 110 subjects during a trial of inhaled corticosteroids (ICS) dose optimization. African American carriers of the minor G allele of the rs2230911 loss-of-function single nucleotide polymorphism were more likely to have a history of prednisone use in the previous 12 months, with adjustment for ICS and long-acting β(2)-agonists use (odds ratio, 2.7; 95% confidence interval, 1.2-6.2; P = 0.018). Despite medium-dose ICS, attenuated pore function predicted earlier exacerbations in incompletely controlled patients with moderate asthma (hazard ratio, 3.2; confidence interval, 1.1-9.3; P = 0.033). After establishing control with low-dose ICS in patients with mild asthma, those with attenuated pore function had more asthma symptoms, rescue albuterol use, and FEV(1) reversal (P < 0.001, 0.03, and 0.03, respectively) during the ICS adjustment phase.

CONCLUSIONS

P2X(7) pore function protects against exacerbations of asthma and loss of control, independent of baseline severity and the maintenance therapy.

The CTSA as an exemplar framework for developing multidisciplinary translational teams

Translational science requires that scientists from multiple disciplines work together to improve the prevention, diagnosis, and treatment of human disease. Although a literature exists on the design and management of multidisciplinary teams, little has been written on multidisciplinary translational teams (MTTs). MTTs are distinct hybrid entities, with goals taken from both industry and academic models. We identified 30 design factors in 10 domains from a literature survey relevant to our MTT model: specific goals, structures, and processes. These dimensions were adapted to our own institutional environment in the selection and management of 11 MTTs that exploited resources of University of Texas Medical Branch (UTMB) Clinical and Translational Sciences Awards (CTSA). Case illustrations of two specific MTTs illustrate some of the challenges encountered and opportunities realized in terms of education and scientific advances. Network depiction of disciplinarity indicated that CTSA KRs and CTSA leadership contributed to discipline diversity especially in small (or nascent) MTTs. A separate depiction of MTT-KR utilization indicated that data analysis, translational technologies, and novel methods were heavily utilized by MTTs, whereas other KRs contributed significant effort to infrastructure development. We conclude that the CTSA can provide a rich infrastructural framework and scientific environment for the development of successful MTTs.

Comparison of physician-, biomarker-, and symptom-based strategies for adjustment of inhaled corticosteroid therapy in adults with asthma: the BASALT randomized controlled trial

CONTEXT

No consensus exists for adjusting inhaled corticosteroid therapy in patients with asthma. Approaches include adjustment at outpatient visits guided by physician assessment of asthma control (symptoms, rescue therapy, pulmonary function), based on exhaled nitric oxide, or on a day-to-day basis guided by symptoms.

OBJECTIVE

To determine if adjustment of inhaled corticosteroid therapy based on exhaled nitric oxide or day-to-day symptoms is superior to guideline-informed, physician assessment-based adjustment in preventing treatment failure in adults with mild to moderate asthma.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, parallel, 3-group, placebo-controlled, multiply-blinded trial of 342 adults with mild to moderate asthma controlled by low-dose inhaled corticosteroid therapy (n = 114 assigned to physician assessment-based adjustment [101 completed], n = 115 to biomarker-based [exhaled nitric oxide] adjustment [92 completed], and n = 113 to symptom-based adjustment [97 completed]), the Best Adjustment Strategy for Asthma in the Long Term (BASALT) trial was conducted by the Asthma Clinical Research Network at 10 academic medical centers in the United States for 9 months between June 2007 and July 2010.

INTERVENTIONS

For physician assessment-based adjustment and biomarker-based (exhaled nitric oxide) adjustment, the dose of inhaled corticosteroids was adjusted every 6 weeks; for symptom-based adjustment, inhaled corticosteroids were taken with each albuterol rescue use.

MAIN OUTCOME MEASURE

The primary outcome was time to treatment failure.

RESULTS

There were no significant differences in time to treatment failure. The 9-month Kaplan-Meier failure rates were 22% (97.5% CI, 14%-33%; 24 events) for physician assessment-based adjustment, 20% (97.5% CI, 13%-30%; 21 events) for biomarker-based adjustment, and 15% (97.5% CI, 9%-25%; 16 events) for symptom-based adjustment. The hazard ratio for physician assessment-based adjustment vs biomarker-based adjustment was 1.2 (97.5% CI, 0.6-2.3). The hazard ratio for physician assessment-based adjustment vs symptom-based adjustment was 1.6 (97.5% CI, 0.8-3.3).

CONCLUSION

Among adults with mild to moderate persistent asthma controlled with low-dose inhaled corticosteroid therapy, the use of either biomarker-based or symptom-based adjustment of inhaled corticosteroids was not superior to physician assessment-based adjustment of inhaled corticosteroids in time to treatment failure.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00495157.

Current prospective of aldose reductase inhibition in the therapy of allergic airway inflammation in asthma

The prevalence of asthma and costs of its care have been continuously increasing, but novel therapeutic options to treat this inflammatory disease have not been brought to the US market. Current therapies such as inhaled steroids, long-acting beta-agonist bronchodilators, antihistamines and immunomodulators may control the symptoms of allergic asthma but fail to modify the underlying disease. Excessive use of steroids and other immunosuppresents alter the patient's quality of life, produce undesirable toxicities, and increase the risk of other pathologies such as diabetes. Hence novel therapeutic options to manage asthma are desirable. In the present review, we have discussed the role of the polyol pathway enzyme aldose reductase (AR) in the amplification of allergic airway inflammation. Recent studies have indicated that AR inhibition prevents the NF-κB-dependent generation of pro-inflammatory cytokines and chemokines in mouse models of allergic airway inflammation indicating the potential use of AR inhibition as a novel tool to control allergic responses. Since orally available AR inhibitors have already undergone phase III clinical trials for diabetic neuropathy and appear to have a manageable side effects profile, they could be readily developed as potential new drugs for the treatment of asthma and related complications.

Benralizumab--a humanized mAb to IL-5Rα with enhanced antibody-dependent cell-mediated cytotoxicity--a novel approach for the treatment of asthma

INTRODUCTION

Benralizumab is a monoclonal antibody that binds the α subunit of the receptor to IL-5. As IL-5 is implicated in disease states that are mediated by eosinophils, benralizumab is an attractive option for use in the management of asthma. As a result of enhanced antibody-directed cell cytotoxicity, it has enhanced eosinophil-depleting activity as compared with neutralizing monoclonal antibody directed against IL-5.

AREAS COVERED

This review presents the available data on benralizumab, including pharmacodynamics, pharmacokinetics, preclinical data and relevant clinical studies.

EXPERT OPINION

Our review indicates that although further investigation is necessary to demonstrate clinical benefit, benralizumab remains a promising treatment modality.

Severe asthma: lessons learned from the National Heart, Lung, and Blood Institute Severe Asthma Research Program

The National Heart, Lung, and Blood Institute Severe Asthma Research Program (SARP) has characterized over the past 10 years 1,644 patients with asthma, including 583 individuals with severe asthma. SARP collaboration has led to a rapid recruitment of subjects and efficient sharing of samples among participating sites to conduct independent mechanistic investigations of severe asthma. Enrolled SARP subjects underwent detailed clinical, physiologic, genomic, and radiological evaluations. In addition, SARP investigators developed safe procedures for bronchoscopy in participants with asthma, including those with severe disease. SARP studies revealed that severe asthma is a heterogeneous disease with varying molecular, biochemical, and cellular inflammatory features and unique structure-function abnormalities. Priorities for future studies include recruitment of a larger number of subjects with severe asthma, including children, to allow further characterization of anatomic, physiologic, biochemical, and genetic factors related to severe disease in a longitudinal assessment to identify factors that modulate the natural history of severe asthma and provide mechanistic rationale for management strategies.

How cytokines co-occur across asthma patients: from bipartite network analysis to a molecular-based classification

Asthmatic patients are currently classified as either severe or non-severe based primarily on their response to glucocorticoids. However, because this classification is based on a post-hoc assessment of treatment response, it does not inform the rational staging of disease or therapy. Recent studies in other diseases suggest that a classification which includes molecular information could lead to more accurate diagnoses and prediction of treatment response. We therefore measured cytokine values in bronchoalveolar lavage (BAL) samples of the lower respiratory tract obtained from 83 asthma patients, and used bipartite network visualizations with associated quantitative measures to conduct an exploratory analysis of the co-occurrence of cytokines across patients. The analysis helped to identify three clusters of patients which had a complex but understandable interaction with three clusters of cytokines, leading to insights for a state-based classification of asthma patients. Furthermore, while the patient clusters were significantly different based on key pulmonary functions, they appeared to have no significant relationship to the current classification of asthma patients. These results suggest the need to define a molecular-based classification of asthma patients, which could improve the diagnosis and treatment of this disease.

Can anti-IgE therapy prevent airway remodeling in allergic asthma?

Airway remodeling is a central feature of asthma. It is exemplified by thickening of the lamina reticularis and structural changes to the epithelium, submucosa, smooth muscle, and vasculature of the airway wall. Airway remodeling may result from persistent airway inflammation. Immunoglobulin E (IgE) is an important mediator of allergic reactions and has a central role in airway inflammation and asthma-related symptoms. Anti-IgE therapies (such as omalizumab) have the potential to block an early step in the allergic cascade and therefore have the potential to reduce airway remodeling. The reduction in free IgE levels following anti-IgE therapy leads to reductions in high-affinity IgE receptor (FcεRI) expression on mast cells, basophils, and dendritic cells. This combined effect results in attenuation of several markers of inflammation, including peripheral and bronchial tissue eosinophilia and levels of granulocyte macrophage colony-stimulating factor, interleukin (IL)-2, IL-4, IL-5, and IL-13. Considering the previously demonstrated anti-inflammatory effects of anti-IgE therapy, along with results from a small study showing continued benefit after discontinuation of long-term treatment, a larger study to assess its effect on markers of airway remodeling is underway.

Meta-analysis of genome-wide association studies of asthma in ethnically diverse North American populations

Asthma is a common disease with a complex risk architecture including both genetic and environmental factors. We performed a meta-analysis of North American genome-wide association studies of asthma in 5,416 individuals with asthma (cases) including individuals of European American, African American or African Caribbean, and Latino ancestry, with replication in an additional 12,649 individuals from the same ethnic groups. We identified five susceptibility loci. Four were at previously reported loci on 17q21, near IL1RL1, TSLP and IL33, but we report for the first time, to our knowledge, that these loci are associated with asthma risk in three ethnic groups. In addition, we identified a new asthma susceptibility locus at PYHIN1, with the association being specific to individuals of African descent (P = 3.9 × 10(-9)). These results suggest that some asthma susceptibility loci are robust to differences in ancestry when sufficiently large samples sizes are investigated, and that ancestry-specific associations also contribute to the complex genetic architecture of asthma.

Differential regulation of the transcriptional activity of the glucocorticoid receptor through site-specific phosphorylation

Post-translational modifications such as phosphorylation are known to play an important role in the gene regulation by the transcription factors including the nuclear hormone receptor superfamily of which the glucocorticoid receptor (GR) is a member. Protein phosphorylation often switches cellular activity from one state to another. Like many other transcription factors, the GR is a phosphoprotein, and phosphorylation plays an important role in the regulation of GR activity. Cell signaling pathways that regulate phosphorylation of the GR and its associated proteins are important determinants of GR function under various physiological conditions. While the role of many phosphorylation sites in the GR is still not fully understood, the role of others is clearer. Several aspects of transcription factor function, including DNA binding affinity, interaction of transactivation domains with the transcription initiation complex, and shuttling between the cytoplasmic compartments, have all been linked to site-specific phosphorylation. All major phosphorylation sites in the human GR are located in the N-terminal domain including the major transactivation domain, AF1. Available literature clearly indicates that many of these potential phosphorylation sites are substrates for multiple kinases, suggesting the potential for a very complex regulatory network. Phosphorylated GR interacts favorably with critical coregulatory proteins and subsequently enhances transcriptional activity. In addition, the activities and specificities of coregulators may be subject to similar regulation by phosphorylation. Regulation of the GR activity due to phosphorylation appears to be site-specific and dependent upon specific cell signaling cascade. Taken together, site-specific phosphorylation and related kinase pathways play an important role in the action of the GR, and more precise mechanistic information will lead to fuller understanding of the complex nature of gene regulation by the GR- and related transcription factors. This review provides currently available information regarding the role of GR phosphorylation in its action, and highlights the possible underlying mechanisms of action.

Detrimental effects of environmental tobacco smoke in relation to asthma severity

BACKGROUND

Environmental tobacco smoke (ETS) has adverse effects on the health of asthmatics, however the harmful consequences of ETS in relation to asthma severity are unknown.

METHODS

In a multicenter study of severe asthma, we assessed the impact of ETS exposure on morbidity, health care utilization and lung functions; and activity of systemic superoxide dismutase (SOD), a potential oxidative target of ETS that is negatively associated with asthma severity.

FINDINGS

From 2002-2006, 654 asthmatics (non-severe 366, severe 288) were enrolled, among whom 109 non-severe and 67 severe asthmatics were routinely exposed to ETS as ascertained by history and validated by urine cotinine levels. ETS-exposure was associated with lower quality of life scores; greater rescue inhaler use; lower lung function; greater bronchodilator responsiveness; and greater risk for emergency room visits, hospitalization and intensive care unit admission. ETS-exposure was associated with lower levels of serum SOD activity, particularly in asthmatic women of African heritage.

INTERPRETATION

ETS-exposure of asthmatic individuals is associated with worse lung function, higher acuity of exacerbations, more health care utilization, and greater bronchial hyperreactivity. The association of diminished systemic SOD activity to ETS exposure provides for the first time a specific oxidant mechanism by which ETS may adversely affect patients with asthma.

Importance of hedgehog interacting protein and other lung function genes in asthma

BACKGROUND

Two recent large meta-analyses of genome-wide association studies of lung function in general populations of European descent identified 11 candidate genes/regions. The importance of these genes in lung function in white and African American subjects with asthma is unknown.

OBJECTIVES

To determine whether genes that regulate lung function in general populations are associated with lung function abnormalities in subjects with asthma from different racial groups.

METHODS

Single nucleotide polymorphisms (SNPs) were tested in 5 asthma populations (N = 1441) for association with pulmonary function, and meta-analysis was performed across populations. The SNPs with the highest significance were then tested for association with bronchodilator reversibility and bronchial hyperresponsiveness to methacholine. A joint analysis of consistently replicated SNPs was performed to predict lung function in asthma.

RESULTS

Hedgehog interacting protein (HHIP) on chromosome 4q31 was associated with lung function in all 5 populations (rs1512288: P(meta) = 9.62E-05 and 3.23E-05 for percent predicted FEV(1) [ppFEV(1)] and percent predicted forced vital capacity [ppFVC], respectively). The SNPs in HHIP were also associated with reversibility (P < .05) but not bronchial hyperresponsiveness to methacholine. Because of differences in linkage disequilibrium in the African American subjects, the most relevant SNPs in HHIP were identified. A subset of normal lung function genes, including HHIP, family with sequence similarity 13, member A (FAM13A), and patched homolog 1 (PTCH1), together predict lung function abnormalities, a measure of severity in white and African American subjects with asthma.

CONCLUSION

A subset of the genes, including HHIP, that regulate lung function in general populations are associated with abnormal lung function in asthma in non-Hispanic white and African American subjects.

Determinants of exhaled breath condensate pH in a large population with asthma

BACKGROUND

Exhaled breath condensate (EBC) pH is 2 log orders below normal during acute asthma exacerbations and returns to normal with antiinflammatory therapy. However, the determinants of EBC pH, particularly in stable asthma, are poorly understood. We hypothesized that patients with severe asthma would have low EBC pH and that there would be an asthma subpopulation of patients with characteristically low values.

METHODS

We studied the association of EBC pH with clinical characteristics in 572 stable subjects enrolled in the Severe Asthma Research Program. These included 250 subjects with severe asthma, 291 with nonsevere asthma, and 31 healthy control subjects.

RESULTS

Overall, EBC in this population of stable, treated study subjects was not lower in severe asthma (8.02; interquartile range [IQR], 7.61-8.41) or nonsevere asthma (7.90; IQR, 7.52-8.20) than in control subjects (7.9; IQR, 7.40-8.20). However, in subjects with asthma the data clustered below and above pH 6.5. Subjects in the subpopulation with pH < 6.5 had lower fraction of exhaled NO (FeNO) values (FeNO = 22.6 ± 18.1 parts per billion) than those with pH ≥ 6.5 (39.9 ± 40.2 parts per billion; P < .0001). By multiple linear regression, low EBC pH was associated with high BMI, high BAL neutrophil counts, low prebronchodilator FEV(1) ratio, high allergy symptoms, race other than white, and gastroesophageal reflux symptoms.

CONCLUSION

Asthma is a complex syndrome. Subjects who are not experiencing an exacerbation but have low EBC pH appear to be a unique subpopulation.

Airway microbiota and bronchial hyperresponsiveness in patients with suboptimally controlled asthma

BACKGROUND

Improvement in lung function after macrolide antibiotic therapy has been attributed to reduction in bronchial infection by specific bacteria. However, the airway might be populated by a more diverse microbiota, and clinical features of asthma might be associated with characteristics of the airway microbiota present.

OBJECTIVE

We sought to determine whether relationships exist between the composition of the airway bacterial microbiota and clinical features of asthma using culture-independent tools capable of detecting the presence and relative abundance of most known bacteria.

METHODS

In this pilot study bronchial epithelial brushings were collected from 65 adults with suboptimally controlled asthma participating in a multicenter study of the effects of clarithromycin on asthma control and 10 healthy control subjects. A combination of high-density 16S ribosomal RNA microarray and parallel clone library-sequencing analysis was used to profile the microbiota and examine relationships with clinical measurements.

RESULTS

Compared with control subjects, 16S ribosomal RNA amplicon concentrations (a proxy for bacterial burden) and bacterial diversity were significantly higher among asthmatic patients. In multivariate analyses airway microbiota composition and diversity were significantly correlated with bronchial hyperresponsiveness. Specifically, the relative abundance of particular phylotypes, including members of the Comamonadaceae, Sphingomonadaceae, Oxalobacteraceae, and other bacterial families were highly correlated with the degree of bronchial hyperresponsiveness.

CONCLUSION

The composition of bronchial airway microbiota is associated with the degree of bronchial hyperresponsiveness among patients with suboptimally controlled asthma. These findings support the need for further functional studies to examine the potential contribution of members of the airway microbiota in asthma pathogenesis.

Bronchoprovocation testing in asthma: effect on exhaled monoxides

Exhaled carbon monoxide and nitric oxide reflect allergic inflammation in asthma and have clinical utility for monitoring disease severity. The effects of allergen challenge and of inflammatory versus non-inflammatory bronchoconstrictive stimuli on the exhalation kinetics of these gases are unclear. The aim of this study is to compare and contrast the effects of methacholine and allergen challenges on the exhaled levels of carbon monoxide and nitric oxide in a cohort of adult subjects with atopic asthma. Eight subjects underwent inhaled allergen testing, nine underwent methacholine testing, and five subjects underwent both tests. Additionally, seven healthy controls underwent a mock challenge. Mixed-expired and end-expiratory carbon monoxide and end-expiratory nitric oxide levels were measured together with spirometry before, during (i.e. after each step of the inhalations), and after the challenges. Decreases in both end-expiratory (-14.4% in 9/11 subjects, p = 0.04) and mixed-expired (-7.5%, 9/11 subjects, p = 0.007) levels of carbon monoxide were noted during the immediate phase of the allergen challenge, with similar reductions after methacholine challenge, but levels were unaffected by repeated forced vital capacity exhalations alone. End-expiratory nitric oxide increased during the immediate phase of allergen challenge in 10/13 subjects (+10.8%, p = 0.05), but decreased after methacholine challenge in 14/14 subjects (-32.2%, p = 0.00009). Bronchospasm negatively modulates exhaled carbon monoxide and nitric oxide, but the inflammatory stimulus of allergen exposure increases exhaled nitric oxide. Measurements of exhaled monoxides may need to be referenced to the FEV(1).

Tiotropium bromide step-up therapy for adults with uncontrolled asthma

BACKGROUND

Long-acting beta-agonist (LABA) therapy improves symptoms in patients whose asthma is poorly controlled by an inhaled glucocorticoid alone. Alternative treatments for adults with uncontrolled asthma are needed.

METHODS

In a three-way, double-blind, triple-dummy crossover trial involving 210 patients with asthma, we evaluated the addition of tiotropium bromide (a long-acting anticholinergic agent approved for the treatment of chronic obstructive pulmonary disease but not asthma) to an inhaled glucocorticoid, as compared with a doubling of the dose of the inhaled glucocorticoid (primary superiority comparison) or the addition of the LABA salmeterol (secondary noninferiority comparison).

RESULTS

The use of tiotropium resulted in a superior primary outcome, as compared with a doubling of the dose of an inhaled glucocorticoid, as assessed by measuring the morning peak expiratory flow (PEF), with a mean difference of 25.8 liters per minute (P<0.001) and superiority in most secondary outcomes, including evening PEF, with a difference of 35.3 liters per minute (P<0.001); the proportion of asthma-control days, with a difference of 0.079 (P=0.01); the forced expiratory volume in 1 second (FEV1) before bronchodilation, with a difference of 0.10 liters (P=0.004); and daily symptom scores, with a difference of -0.11 points (P<0.001). The addition of tiotropium was also noninferior to the addition of salmeterol for all assessed outcomes and increased the prebronchodilator FEV1 more than did salmeterol, with a difference of 0.11 liters (P=0.003).

CONCLUSIONS

When added to an inhaled glucocorticoid, tiotropium improved symptoms and lung function in patients with inadequately controlled asthma. Its effects appeared to be equivalent to those with the addition of salmeterol. (Funded by the National Heart, Lung, and Blood Institute; ClinicalTrials.gov number, NCT00565266.).

A trial of clarithromycin for the treatment of suboptimally controlled asthma

BACKGROUND

PCR studies have demonstrated evidence of Mycoplasma pneumoniae and Chlamydophila pneumoniae in the lower airways of patients with asthma.

OBJECTIVE

To test the hypothesis that clarithromycin would improve asthma control in individuals with mild-to-moderate persistent asthma that was not well controlled despite treatment with low-dose inhaled corticosteroids.

METHODS

Adults with an Asthma Control Questionnaire score ≥1.5 after a 4-week period of treatment with fluticasone propionate were entered into a PCR-stratified randomized, controlled trial to evaluate the effect of 16 weeks of either clarithromycin or placebo, added to fluticasone, on asthma control in individuals with or without lower airway PCR evidence of M pneumoniae or C pneumoniae.

RESULTS

A total of 92 participants were randomized. Twelve (13%) subjects demonstrated PCR evidence of M pneumoniae or C pneumoniae in endobronchial biopsies; 80 were PCR-negative for both organisms. In PCR-positive participants, clarithromycin yielded a 0.4 ± 0.4 unit improvement in the Asthma Control Questionnaire score, with a 0.1 ± 0.3 unit improvement in those allocated to placebo. This between-group difference of 0.3 ± 0.5 (P = .6) was neither clinically nor statistically significant. In PCR-negative participants, a nonsignificant between-group difference of 0.2 ± 0.2 units (P = .3) was observed. Clarithromycin did not improve lung function or airway inflammation but did improve airway hyperresponsiveness, increasing the methacholine PC(20) by 1.2 ± 0.5 doubling doses (P = .02) in the study population.

CONCLUSION

Adding clarithromycin to fluticasone in adults with mild-to-moderate persistent asthma that was suboptimally controlled by low-dose inhaled corticosteroids alone did not further improve asthma control. Although there was an improvement in airway hyperresponsiveness with clarithromycin, this benefit was not accompanied by improvements in other secondary outcomes.

Predicting intermediate phenotypes in asthma using bronchoalveolar lavage-derived cytokines

An important problem in realizing personalized medicine is the development of methods for identifying disease subtypes using quantitative proteomics. Recently we found that bronchoalveolar lavage (BAL) cytokine patterns contain information about dynamic lung responsiveness. In this study, we examined physiological data from 1,048 subjects enrolled in the US Severe Asthma Research Program (SARP) to identify four largely separable, quantitative intermediate phenotypes. Upper extremes in the study population were identified for eosinophil- or neutrophil-predominant inflammation, bronchodilation in response to albuterol treatment, or methacholine sensitivity. We evaluated four different statistical ("machine") learning methods to predict each intermediate phenotype using BAL A-cytokine measurements on a 76 subject subset. Comparison of these models using area under the ROC curve and overall classification accuracy indicated that logistic regression and multivariate adaptive regression splines produced the most accurate methods to predict intermediate asthma phenotypes. These robust classification methods will aid future translational studies in asthma targeted at specific intermediate phenotypes.

Albuterol enantiomers: pre-clinical and clinical value?

Albuterol has been used in the acute treatment of asthma exacerbations for over 25 years. Its cost is low, and delivery can be tailored to allow dose-effect titration. Like other beta-2-adrenergic receptor agonists, it can exist as a racemate of two enantiomers, one active ((R)-albuterol), and one traditionally considered inert ((S)-albuterol). Basic investigations in airway cells and models from animals and humans have shown that (R)-albuterol, in both racemic and single enantiomer formulations, produces changes consistent with both relaxation of airway smooth muscle cells, and the reduction of inflammation. In contrast, (S)-albuterol typically has produces effects opposite to those of (R)-albuterol, i.e., antagonistic to the beneficial desired effects. Coupled with the fact that (S)-albuterol can persist 12 times longer than (R)-albuterol within the human circulation, findings suggest that paradoxical effects, sometimes seen with chronic racemic albuterol use, are due to (S)-albuterol. A number of clinical studies, to date, have been generally consistent with these findings; however, overwhelming evidence for clinical superiority of the (R)-albuterol single enantiomer over that within racemic albuterol remains to be obtained.

Identification of asthma phenotypes using cluster analysis in the Severe Asthma Research Program

RATIONALE

The Severe Asthma Research Program cohort includes subjects with persistent asthma who have undergone detailed phenotypic characterization. Previous univariate methods compared features of mild, moderate, and severe asthma.

OBJECTIVES

To identify novel asthma phenotypes using an unsupervised hierarchical cluster analysis.

METHODS

Reduction of the initial 628 variables to 34 core variables was achieved by elimination of redundant data and transformation of categorical variables into ranked ordinal composite variables. Cluster analysis was performed on 726 subjects.

MEASUREMENTS AND MAIN RESULTS

Five groups were identified. Subjects in Cluster 1 (n = 110) have early onset atopic asthma with normal lung function treated with two or fewer controller medications (82%) and minimal health care utilization. Cluster 2 (n = 321) consists of subjects with early-onset atopic asthma and preserved lung function but increased medication requirements (29% on three or more medications) and health care utilization. Cluster 3 (n = 59) is a unique group of mostly older obese women with late-onset nonatopic asthma, moderate reductions in FEV(1), and frequent oral corticosteroid use to manage exacerbations. Subjects in Clusters 4 (n = 120) and 5 (n = 116) have severe airflow obstruction with bronchodilator responsiveness but differ in to their ability to attain normal lung function, age of asthma onset, atopic status, and use of oral corticosteroids.

CONCLUSIONS

Five distinct clinical phenotypes of asthma have been identified using unsupervised hierarchical cluster analysis. All clusters contain subjects who meet the American Thoracic Society definition of severe asthma, which supports clinical heterogeneity in asthma and the need for new approaches for the classification of disease severity in asthma.

Use of exhaled nitric oxide measurement to identify a reactive, at-risk phenotype among patients with asthma

RATIONALE

Exhaled nitric oxide (Fe(NO)) is a biomarker of airway inflammation in mild to moderate asthma. However, whether Fe(NO) levels are informative regarding airway inflammation in patients with severe asthma, who are refractory to conventional treatment, is unknown. Here, we hypothesized that classification of severe asthma based on airway inflammation as defined by Fe(NO) levels would identify a more reactive, at-risk asthma phenotype.

METHODS

Fe(NO) and major features of asthma, including airway inflammation, airflow limitation, hyperinflation, hyperresponsiveness, and atopy, were determined in 446 individuals with various degrees of asthma severity (175 severe, 271 non-severe) and 49 healthy subjects enrolled in the Severe Asthma Research Program.

MEASUREMENTS AND MAIN RESULTS

Fe(NO) levels were similar among patients with severe and non-severe asthma. The proportion of individuals with high Fe(NO) levels (>35 ppb) was the same (40%) among groups despite greater corticosteroid therapy in severe asthma. All patients with asthma and high Fe(NO) had more airway reactivity (maximal reversal in response to bronchodilator administration and by methacholine challenge), more evidence of allergic airway inflammation (sputum eosinophils), more evidence of atopy (positive skin tests, higher serum IgE and blood eosinophils), and more hyperinflation, but decreased awareness of their symptoms. High Fe(NO) identified those patients with severe asthma characterized by the greatest airflow obstruction and hyperinflation and most frequent use of emergency care.

CONCLUSIONS

Grouping of asthma by Fe(NO) provides an independent classification of asthma severity, and among patients with severe asthma identifies the most reactive and worrisome asthma phenotype.

Effect of beta2-adrenergic receptor polymorphism on response to longacting beta2 agonist in asthma (LARGE trial): a genotype-stratified, randomised, placebo-controlled, crossover trial

BACKGROUND

Some studies suggest that patients with asthma who are homozygous for arginine at the 16th amino acid position of the beta2-adrenergic receptor (B16 Arg/Arg) benefit less from treatment with longacting beta2 agonists and inhaled corticosteroids than do those homozygous for glycine (B16 Gly/Gly). We investigated whether there is a genotype-specific response to treatment with a longacting beta2 agonist in combination with inhaled corticosteroid.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled trial, adult patients with moderate asthma were enrolled in pairs matched for forced expiratory volume in 1 s and ethnic origin, according to whether they had the B16 Arg/Arg (n=42) or B16 Gly/Gly (n=45) genotype. Individuals in a matched pair were randomly assigned by computer-generated randomisation sequence to receive inhaled longacting beta2 agonist (salmeterol 50 microg twice a day) or placebo given in a double-blind, crossover design for two 18-week periods. Open-label inhaled corticosteroid (hydrofluoroalkane beclometasone 240 microg twice a day) was given to all participants during the treatment periods. The primary endpoint was morning peak expiratory flow (PEF). Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00200967.

FINDINGS

After 18 weeks of treatment, mean morning PEF in Arg/Arg participants was 21.4 L/min (95% CI 11.8-31.1) higher when participants were assigned to receive salmeterol than when assigned to receive placebo (p<0.0001). In Gly/Gly participants, morning PEF was 21.5 L/min (11.0-32.1) higher when participants were assigned to receive salmeterol than when assigned to receive placebo (p<0.0001). The improvement in PEF did not differ between genotypes (difference [Arg/Arg-Gly/Gly] -0.1, -14.4 to 14.2; p=0.99). In Gly/Gly participants, methacholine PC20 (20% reduction in forced expiratory volume in 1 s; a prespecified secondary outcome) was 2.4 times higher when participants were assigned to salmeterol than when assigned to placebo (p<0.0001). Responsiveness to methacholine did not differ between salmeterol and placebo in Arg/Arg participants (p=0.87). The 2.5 times higher genotype-specific difference in responsiveness to methacholine was significant (1.32 doubling dose difference between genotypes, 0.43-2.21, p=0.0038). Seven Arg/Arg participants (placebo, n=5; salmeterol, n=2) and six Gly/Gly participants (placebo, n=3; salmeterol, n=3) had an asthma exacerbation. Five serious adverse events were reported, one each during the pre-match and run-in phases on open-label inhaled corticosteroid, two during double-blind treatment with salmeterol/inhaled corticosteroid, and one during double-blind treatment with placebo/inhaled corticosteroid. None of the serious events was asthma-related or related to study drugs or procedures.

INTERPRETATION

In asthma patients with B16 Arg/Arg and B16 Gly/Gly genotypes, combination treatment with salmeterol and inhaled corticosteroid improved airway function when compared with inhaled corticosteroid therapy alone. These findings suggest that patients should continue to be treated with longacting beta2 agonists plus moderate-dose inhaled corticosteroids irrespective of B16 genotype. Further investigation is needed to establish the importance of the genotype-specific difference in responsiveness to methacholine.

FUNDING

National Institutes of Health.

Effect of an Experimental Rhinovirus 16 Infection on Airway Mediator Response to Antigen

Viral respiratory infections provoke wheezing in many patients with asthma. It is our hypothesis that viral respiratory infections enhance the airway inflammatory response to antigen, thus provoking increased wheezing. To evaluate this possibility, 8 patients with allergic rhinitis were experimentally inoculated with rhinovirus (RV) 16. The airway response to antigen was evaluated by segmental bronchoprovocation with antigen. During the RV infection, and at recovery 4 weeks later, there was enhanced histamine release and recruitment of cells, particularly eosinophils, to the airway with antigen challenge. These findings suggest that RV infection can enhance the airway inflammatory response to antigen.

Predicting worsening asthma control following the common cold

The asthmatic response to the common cold is highly variable, and early characteristics that predict worsening of asthma control following a cold have not been identified. In this prospective multicentric cohort study of 413 adult subjects with asthma, the mini-Asthma Control Questionnaire (mini-ACQ) was used to quantify changes in asthma control and the Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21) to measure cold severity. Univariate and multivariable models were used to examine demographic, physiological, serological and cold-related characteristics for their relationship to changes in asthma control following a cold. Clinically significant worsening of asthma control was observed following a cold (mean+/-SD increase in mini-ACQ score of 0.69+/-0.93). Univariate analysis demonstrated that season, centre location, cold duration and cold severity measurements were all associated with a change in asthma control. Multivariable analysis of the covariates available within the first 2 days of cold onset revealed that the day 2 and cumulative sum of day 1 and 2 WURSS-21 scores were significant predictors of the subsequent changes in asthma control. In asthmatic subjects, cold severity within the first 2 days can be used to predict subsequent changes in asthma control. This information may help clinicians prevent deterioration in asthma control following a cold.

Alterations of the arginine metabolome in asthma

RATIONALE

As the sole nitrogen donor in nitric oxide (NO) synthesis and key intermediate in the urea cycle, arginine and its metabolic pathways are integrally linked to cellular respiration, metabolism, and inflammation.

OBJECTIVES

We hypothesized that arginine (Arg) bioavailability would be associated with airflow abnormalities and inflammation in subjects with asthma, and would be informative for asthma severity.

METHODS

Arg bioavailability was assessed in subjects with severe and nonsevere asthma and healthy control subjects by determination of plasma Arg relative to its metabolic products, ornithine and citrulline, and relative to methylarginine inhibitors of NO synthases, and by serum arginase activity. Inflammatory parameters, including fraction of exhaled NO (Fe(NO)), IgE, skin test positivity to allergens, bronchoalveolar lavage, and blood eosinophils, were also evaluated.

MEASUREMENTS AND MAIN RESULTS

Subjects with asthma had greater Arg bioavailability, but also increased Arg catabolism compared with healthy control subjects, as evidenced by higher levels of Fe(NO) and serum arginase activity. However, Arg bioavailability was positively associated with Fe(NO) only in healthy control subjects; Arg bioavailability was unrelated to Fe(NO) or other inflammatory parameters in severe or nonsevere asthma. Inflammatory parameters were related to airflow obstruction and reactivity in nonsevere asthma, but not in severe asthma. Conversely, Arg bioavailability was related to airflow obstruction in severe asthma, but not in nonsevere asthma. Modeling confirmed that measures of Arg bioavailabilty predict airflow obstruction only in severe asthma.

CONCLUSIONS

Unlike Fe(NO), Arg bioavailability is not a surrogate measure of inflammation; however, Arg bioavailability is strongly associated with airflow abnormalities in severe asthma.

Airway lipoxin A4 generation and lipoxin A4 receptor expression are decreased in severe asthma

RATIONALE

Airway inflammation is common in severe asthma despite antiinflammatory therapy with corticosteroids. Lipoxin A(4) (LXA(4)) is an arachidonic acid-derived mediator that serves as an agonist for resolution of inflammation.

OBJECTIVES

Airway levels of LXA(4), as well as the expression of lipoxin biosynthetic genes and receptors, in severe asthma.

METHODS

Samples of bronchoalveolar lavage fluid were obtained from subjects with asthma and levels of LXA(4) and related eicosanoids were measured. Expression of lipoxin biosynthetic genes was determined in whole blood, bronchoalveolar lavage cells, and endobronchial biopsies by quantitative polymerase chain reaction, and leukocyte LXA(4) receptors were monitored by flow cytometry.

MEASUREMENTS AND MAIN RESULTS

Individuals with severe asthma had significantly less LXA(4) in bronchoalveolar lavage fluids (11.2 +/- 2.1 pg/ml) than did subjects with nonsevere asthma (150.1 +/- 38.5 pg/ml; P < 0.05). In contrast, levels of cysteinyl leukotrienes were increased in both asthma cohorts compared with healthy individuals. In severe asthma, 15-lipoxygenase-1 mean expression was decreased fivefold in bronchoalveolar lavage cells. In contrast, 15-lipoxgenase-1 was increased threefold in endobronchial biopsies, but expression of both 5-lipoxygenase and 15-lipoxygenase-2 in these samples was decreased. Cyclooxygenase-2 expression was decreased in all anatomic compartments sampled in severe asthma. Moreover, LXA(4) receptor gene and protein expression were significantly decreased in severe asthma peripheral blood granulocytes.

CONCLUSIONS

Mechanisms underlying pathological airway responses in severe asthma include lipoxin underproduction with decreased expression of lipoxin biosynthetic enzymes and receptors. Together, these results indicate that severe asthma is characterized, in part, by defective lipoxin counterregulatory signaling circuits.

Non-invasive measurements of exhaled NO and CO associated with methacholine responses in mice

Background

Nitric oxide (NO) and carbon monoxide (CO) in exhaled breath are considered obtainable biomarkers of physiologic mechanisms. Therefore, obtaining their measures simply, non-invasively, and repeatedly, is of interest, and was the purpose of the current study.

Methods

Expired NO (E_NO) and CO (E_CO) were measured non-invasively using a gas micro-analyzer on several strains of mice (C57Bl6, IL-10^-/-, A/J, MKK3^-/-, JNK1^-/-, NOS-2^-/- and NOS-3^-/-) with and without allergic airway inflammation (AI) induced by ovalbumin systemic sensitization and aerosol challenge, compared using independent-sample t-tests between groups, and repeated measures analysis of variance (ANOVA) within groups over time of inflammation induction. E_NO and E_CO were also measured in C57Bl6 and IL-10-/- mice, ages 8–58 weeks old, the relationship of which was determined by regression analysis. S-methionyl-L-thiocitrulline (SMTC), and tin protoporphyrin (SnPP) were used to inhibit neuronal/constitutive NOS-1 and heme-oxygenase, respectively, and alter NO and CO production, respectively, as assessed by paired t-tests. Methacholine-associated airway responses (AR) were measured by the enhanced pause method, with comparisons by repeated measures ANOVA and post-hoc testing.

Results

E_NO was significantly elevated in naïve IL-10^-/- (9–14 ppb) and NOS-2^-/- (16 ppb) mice as compared to others (average: 5–8 ppb), whereas E_CO was significantly higher in naïve A/J, NOS-3^-/- (3–4 ppm), and MKK3^-/- (4–5 ppm) mice, as compared to others (average: 2.5 ppm). As compared to C57Bl6 mice, AR of IL-10^-/-, JNK1^-/-, NOS-2^-/-, and NOS-3^-/- mice were decreased, whereas they were greater for A/J and MKK3^-/- mice. SMTC significantly decreased E_NO by ~30%, but did not change AR in NOS-2^-/- mice. SnPP reduced E_CO in C57Bl6 and IL-10^-/- mice, and increased AR in NOS-2^-/- mice. E_NO decreased as a function of age in IL-10^-/- mice, remaining unchanged in C57Bl6 mice.

Conclusion

These results are consistent with the ideas that: 1) E_NO is associated with mouse strain and knockout differences in NO production and AR, 2) alterations of E_NO and E_CO can be measured non-invasively with induction of allergic AI or inhibition of key gas-producing enzymes, and 3) alterations in AR may be dependent on the relative balance of NO and CO in the airway.

Effect of nebulized arformoterol on airway function in COPD: results from two randomized trials

RATIONALE

Arformoterol, a single isomer long-acting beta(2)-agonist, was developed as an inhalation solution for the maintenance treatment of bronchoconstriction in COPD.

METHODS

The pulmonary function efficacy of nebulized arformoterol (15 micro g BID, 25 micro g BID, 50 micro g QD) and salmeterol MDI (42 micro g BID) versus placebo was assessed in 1456 subjects (mean FEV(1) 1.2L, mean predicted 41%). Data were pooled from 2 identical, 12-week, double-blind, randomized trials. The percent change in trough FEV(1), percent change in FEV(1) average AUC((0 - 12 hrs)) and peak percent change FEV(1) from predose were analyzed.

RESULTS

Improvement in trough FEV(1) averaged over 12 weeks was greater for arformoterol and salmeterol versus placebo (mean differences from placebo [95% CI] arformoterol-15 micro g BID: 11.4% [8.4, 14.3]; 25 micro g BID: 15.4% [12.2, 18.6]; 50 micro g QD: 10.9% [7.9, 13.9]); salmeterol: (11.6% [8.8, 14.4]). Greater improvements versus placebo occurred after the first dose (mean differences between arformoterol and placebo for trough FEV(1): 13-19%; FEV(1) AUC((0 - 12 hrs)): 19-24%; peak percent change: 20-25%) and at week 12 (trough FEV(1): 10-13%; FEV(1) AUC((0 - 12 hrs)): 6-13%; peak percent change: 7-14%); all 95% CIs excluded zero. Increases in FEV(1) AUC((0 - 12 hrs)) and peak percent change were greater for arformoterol than for salmeterol (95% CIs excluded zero). After 12 weeks, 78-87% of arformoterol subjects had > or = 10% increases in FEV(1) from pre-dose (56% salmeterol, 44% placebo); the median time to response was 3-13 minutes (142 minutes salmeterol).

CONCLUSIONS

In these trials, COPD subjects administered nebulized arformoterol demonstrated significant and sustained improvement in lung function over 12 weeks.

Molecular phenotyping of severe asthma using pattern recognition of bronchoalveolar lavage-derived cytokines

BACKGROUND

Asthma is a heterogeneous clinical disorder. Methods for objective identification of disease subtypes will focus on clinical interventions and help identify causative pathways. Few studies have explored phenotypes at a molecular level.

OBJECTIVE

We sought to discriminate asthma phenotypes on the basis of cytokine profiles in bronchoalveolar lavage (BAL) samples from patients with mild-moderate and severe asthma.

METHODS

Twenty-five cytokines were measured in BAL samples of 84 patients (41 severe, 43 mild-moderate) using bead-based multiplex immunoassays. The normalized data were subjected to statistical and informatics analysis.

RESULTS

Four groups of asthmatic profiles could be identified on the basis of unsupervised analysis (hierarchical clustering) that were independent of treatment. One group, enriched in patients with severe asthma, showed differences in BAL cellular content, reductions in baseline pulmonary function, and enhanced response to methacholine provocation. Ten cytokines were identified that accurately predicted this group. Classification methods for predicting methacholine sensitivity were developed. The best model analysis predicted hyperresponders with 88% accuracy in 10 trials by using a 10-fold cross-validation. The cytokines that contributed to this model were IL-2, IL-4, and IL-5. On the basis of this classifier, 3 distinct hyperresponder classes were identified that varied in BAL eosinophil count and PC20 methacholine.

CONCLUSION

Cytokine expression patterns in BAL can be used to identify distinct types of asthma and identify distinct subsets of methacholine hyperresponders. Further biomarker discovery in BAL may be informative.

Lung function in adults with stable but severe asthma: air trapping and incomplete reversal of obstruction with bronchodilation

Five to ten percent of asthma cases are poorly controlled chronically and refractory to treatment, and these severe cases account for disproportionate asthma-associated morbidity, mortality, and health care utilization. While persons with severe asthma tend to have more airway obstruction, it is not known whether they represent the severe tail of a unimodal asthma population, or a severe asthma phenotype. We hypothesized that severe asthma has a characteristic physiology of airway obstruction, and we evaluated spirometry, lung volumes, and reversibility during a stable interval in 287 severe and 382 nonsevere asthma subjects from the National Heart, Lung, and Blood Institute Severe Asthma Research Program. We partitioned airway obstruction into components of air trapping [indicated by forced vital capacity (FVC)] and airflow limitation [indicated by forced expiratory volume in 1 s (FEV(1))/FVC]. Severe asthma had prominent air trapping, evident as reduced FVC over the entire range of FEV(1)/FVC. This pattern was confirmed with measures of residual lung volume/total lung capacity (TLC) in a subgroup. In contrast, nonsevere asthma did not exhibit prominent air trapping, even at FEV(1)/FVC <75% predicted. Air trapping also was associated with increases in TLC and functional reserve capacity. After maximal bronchodilation, FEV(1) reversed similarly from baseline in severe and nonsevere asthma, but the severe asthma classification was an independent predictor of residual reduction in FEV(1) after maximal bronchodilation. An increase in FVC accounted for most of the reversal of FEV(1) when baseline FEV(1) was <60% predicted. We conclude that air trapping is a characteristic feature of the severe asthma population, suggesting that there is a pathological process associated with severe asthma that makes airways more vulnerable to this component.

Nebulized arformoterol in patients with COPD: a 12-week, multicenter, randomized, double-blind, double-dummy, placebo- and active-controlled trial

OBJECTIVE

The aim of this study was to assess the efficacy and tolerability of nebulized arformoterol tartrate (a selective, long-acting beta(2)-adrenergic agonist that is the [R,R] isomer of formoterol) and salmeterol xinafoate versus placebo in patients with chronic obstructive pulmonary disease (COPD).

METHODS

This 12-week, multicenter, randomized, double-blind, double-dummy, placebo- and active-controlled trial was conducted at 60 centers across the United States. Male and female patients aged >or=35 years with physician-diagnosed COPD received arformoterol (15 microg BID, 25 microg BID, or 50 microg QD via nebulizer), salmeterol (42 microg BID via metered dose inhaler), or placebo. Pulmonary function was assessed by spirometry; dyspnea, by the Transitional Dyspnea Index (TDI); and health status, by the St. George's Respiratory Questionnaire (SGRQ). Adverse events (AEs) were assessed by site personnel at all clinic visits (screening, first dose at week 0, and at weeks 3, 6, 9, 12, and follow-up). COPD exacerbations were defined as worsening respiratory status requiring a change in medication or an unscheduled provider visit.

RESULTS

A total of 717 patients received study medication. The demographic composition of all treatment arms was similar. The mean age was 62.9 years, 58% were men, and mean baseline forced expiratory volume in 1 second (FEV(1)) was 1.2 L (41% predicted). Mean improvement in trough FEV(1) over 12 weeks was significantly greater with all 3 arformoterol doses (15 microg BID, +16.9%; 25 microg BID, +18.9%; 50 microg QD, +14.9%) and for salmeterol (+17.4%) relative to placebo (+6.0%; P < 0.001). There were significantly greater improvements in the mean percentage change in FEV(1) AUC(0-12h) from the predose value over 12 weeks (15 microg BID, 12.7%, 25 microg BID, 13.9%, 50 microg QD, 18.9%; salmeterol, 9.8%) versus placebo (2.7%; P <or= 0.001); all doses of arformoterol were statistically different from salmeterol for this end point (P <or= 0.024). At week 12, TDI focal scores were significantly greater with all arformoterol doses compared with placebo (mean [95% CI]: 15 microg BID, 0.97 [0.25-1.69]; 25 microg BID, 1.08 [0.3-1.86]; 50 microg QD, 1.04 [0.32-1.771), suggesting treatment-associated improvement in dyspnea, however, the difference between salmeterol and placebo was not statistically significant (0.36 [-0.40 to 1.12]). Improvements in health status, as measured using SGRQ total scores, were -2.6 to -3.6 U in the arformoterol groups, -4.4 U for salmeterol, and -1.2 U for placebo; 95% CI of differences versus placebo suggested significant improvement for the arformoterol 25 microg BID and salmeterol groups. There was a similar frequency of AEs and COPD exacerbations across all groups, including placebo.

CONCLUSIONS

In this trial, patients with moderate to severe COPD administered nebulized arformoterol over 12 weeks were observed to have significant and sustained improvements in airway function and dyspnea compared with placebo. The results also suggest that all doses of arformoterol, including the lowest dose (15 microg BID), were effective. Overall, nebulized arformoterol was well tolerated.

IL4R alpha mutations are associated with asthma exacerbations and mast cell/IgE expression

BACKGROUND

Severe asthma has been associated with severe exacerbations, lower lung function and greater tissue inflammation. Previous studies have suggested that mutations in interleukin-4 receptor alpha (IL4Ralpha) are associated with lower lung function, higher IgE, and a gain in receptor function. However, an effect on exacerbations and tissue inflammation has not been shown.

HYPOTHESIS

Allelic substitutions in IL4Ralpha are associated with asthma exacerbations, lower lung function, and tissue inflammation, in particular to mast cells and IgE.

METHODS

Two well-characterized cohorts of subjects with severe asthma were analyzed for five single nucleotide polymorphisms (SNPs) in IL4Ralpha. These polymorphisms were compared with the history of severe asthma exacerbations and lung function. In the primary (National Jewish) cohort, these polymorphisms were also compared with endobronchial tissue inflammatory cells and local IgE.

RESULTS

In both cohorts, the presence of the minor alleles at E375A and Q551R, which were more common in African Americans, was associated with a history of severe exacerbations and lower lung function. In the National Jewish cohort, the C allele at E375A was associated with higher tissue mast cells and higher levels of IgE bound to mast cells. The significance for most of these associations remained when whites (the larger racial subgroup) were analyzed separately.

CONCLUSIONS

SNPs in IL4Ralpha, which are more common in African Americans, are associated with severe asthma exacerbations, lower lung function, and increased mast cell-related tissue inflammation. Further studies of the impact of these mutations in African Americans and on receptor function are indicated.

(R)-albuterol for asthma: pro [a.k.a. (S)-albuterol for asthma: con]

Is there scientific evidence to support the replacement of the beta-agonist racemic albuterol with levalbuterol--that is, (R)-albuterol? The argument presented further refines the question as "Do we wish to continue to treat asthma with a mixture of albuterol, of which half is an agent with no known benefit--that is, (S)-albuterol--and which may exacerbate the disease?"

The role of leukotrienes in airway inflammation

Cysteinyl leukotrienes (cysLTs) are a class of closely structurally related lipid molecules, originally described as slow-reacting substance of anaphylaxis, with a myriad of biologic functions. These activities include producing smooth muscle contraction and mucus secretion, recruiting allergic inflammatory cells, modulating cytokine production, influencing neural transmission, and altering structural changes in the airway. Administration of cysLTs to animals and human subjects reproduces many features of allergic inflammation and asthma. Leukotriene (LT) blockers have independent efficacy in asthma and improve pulmonary function when added to inhaled steroids. Conversely, blockade of this pathway both in animals and in human subjects results in important reductions in inflammation and its consequences and might reduce structural changes of remodeling. These data collectively make a compelling case for an important role of cysLTs in airway inflammation and asthma. However, the magnitude of effect of anti-LTs is smaller than that of corticosteroids, and there is more variability in benefit of LT blockade than is seen with inhaled steroids. In addition, adding anti-LTs to inhaled steroids in asthmatic patients does not appear to produce added anti-inflammatory benefit. Genetic polymorphisms and environmental factors, such as tobacco smoke exposure, might underlie some of the heterogeneity of response to LT blockers.

In vitro cytotoxicity of Manville Code 100 glass fibers: effect of fiber length on human alveolar macrophages

BACKGROUND

Synthetic vitreous fibers (SVFs) are inorganic noncrystalline materials widely used in residential and industrial settings for insulation, filtration, and reinforcement purposes. SVFs conventionally include three major categories: fibrous glass, rock/slag/stone (mineral) wool, and ceramic fibers. Previous in vitro studies from our laboratory demonstrated length-dependent cytotoxic effects of glass fibers on rat alveolar macrophages which were possibly associated with incomplete phagocytosis of fibers >or= 17 microm in length. The purpose of this study was to examine the influence of fiber length on primary human alveolar macrophages, which are larger in diameter than rat macrophages, using length-classified Manville Code 100 glass fibers (8, 10, 16, and 20 microm). It was hypothesized that complete engulfment of fibers by human alveolar macrophages could decrease fiber cytotoxicity; i.e. shorter fibers that can be completely engulfed might not be as cytotoxic as longer fibers. Human alveolar macrophages, obtained by segmental bronchoalveolar lavage of healthy, non-smoking volunteers, were treated with three different concentrations (determined by fiber number) of the sized fibers in vitro. Cytotoxicity was assessed by monitoring cytosolic lactate dehydrogenase release and loss of function as indicated by a decrease in zymosan-stimulated chemiluminescence.

RESULTS

Microscopic analysis indicated that human alveolar macrophages completely engulfed glass fibers of the 20 microm length. All fiber length fractions tested exhibited equal cytotoxicity on a per fiber basis, i.e. increasing lactate dehydrogenase and decreasing chemiluminescence in the same concentration-dependent fashion.

CONCLUSION

The data suggest that due to the larger diameter of human alveolar macrophages, compared to rat alveolar macrophages, complete phagocytosis of longer fibers can occur with the human cells. Neither incomplete phagocytosis nor length-dependent toxicity was observed in fiber-exposed human macrophage cultures. In contrast, rat macrophages exhibited both incomplete phagocytosis of long fibers and length-dependent toxicity. The results of the human and rat cell studies suggest that incomplete engulfment may enhance cytotoxicity of fiber glass. However, the possibility should not be ruled out that differences between human versus rat macrophages other than cell diameter could account for differences in fiber effects.

Inhibition of phosphodiesterase 4 amplifies cytokine-dependent induction of arginase in macrophages

Arginase is greatly elevated in asthma and is thought to play a role in the pathophysiology of this disease. As inhibitors of phosphodiesterase 4 (PDE4), the predominant PDE in macrophages, elevate cAMP levels and reduce inflammation, they have been proposed for use in treatment of asthma and chronic obstructive pulmonary disease. As cAMP is an inducer of arginase, we tested the hypothesis that a PDE4 inhibitor would enhance macrophage arginase induction by key cytokines implicated in asthma and other pulmonary diseases. RAW 264.7 cells were stimulated with IL-4 or transforming growth factor (TGF)-beta, with and without the PDE4 inhibitor rolipram. IL-4 and TGF-beta increased arginase activity 16- and 5-fold, respectively. Rolipram alone had no effect but when combined with IL-4 and TGF-beta synergistically enhanced arginase activity by an additional 15- and 5-fold, respectively. The increases in arginase I protein and mRNA levels mirrored increases in arginase activity. Induction of arginase II mRNA was also enhanced by rolipram but to a much lesser extent than arginase I. Unlike its effect in RAW 264.7 cells, IL-4 alone did not increase arginase activity in human alveolar macrophages (AM) from healthy volunteers. However, combining IL-4 with agents to induce cAMP levels induced arginase activity in human AM significantly above the level obtained with cAMP-inducing agents alone. In conclusion, agents that elevate cAMP significantly enhance induction of arginase by cytokines. Therefore, consequences of increased arginase expression should be evaluated whenever PDE inhibitors are proposed for treatment of inflammatory disorders in which IL-4 and/or TGF-beta predominate.

Alterations in nitric oxide and cytokine production with airway inflammation in the absence of IL-10

IL-10 is an anti-inflammatory cytokine that suppresses NO synthase (NOS) and production of NO; its lack may promote NO production and alterations in cytokines modulated by NO with allergic airway inflammation (AI), such as IL-18 and IL-4. Therefore, we induced AI in IL-10 knockout ((-/-)) and IL-10-sufficient C57BL/6 (C57) mice with inhaled OVA and measured airway NO production, as exhaled NO (E(NO)) and bronchoalveolar lavage fluid nitrite levels. E(NO) and nitrite levels were elevated significantly in naive IL-10(-/-) mice as compared with C57 mice. With AI, E(NO) and nitrite levels increased in C57 mice and decreased in IL-10(-/-) mice. IL-18 production fell with both AI and addition of S-nitroso-N-acetyl-d,l-penicillamine (a NO donor) but was not significantly increased by chemical NOS inhibition by l-N(5)-(1-iminoethyl)-ornithine. IL-4 AI was increased significantly (up to 10-fold greater) in the absence of IL-10 but was reduced significantly with chemical inhibition of NOS. Airway responsiveness was lower in IL-10(-/-) mice and was associated with alteration in production of NO and IL-4. Thus, IL-4 production was increased, and likely decreased NO production, in a way not predicted by the absence of IL-10. Inhibition of IL-4 production, with inhibition of NOS in the absence of IL-10, demonstrated the importance of a NO and IL-4 feedback mechanism regulating this interaction.

Modulation of GM-CSF release by enantiomers of beta-agonists in human airway smooth muscle

BACKGROUND

beta 2 -Adrenergic receptor agonists can reduce the release of GM-CSF by human airway smooth muscle cells (HASMCs). These effects are considered anti-inflammatory and are ascribed to the activity of the (R)-enantiomer within the racemate of the agonist. However, the effect of the (S)-enantiomer on GM-CSF release, once thought to be inert, has not been extensively explored. Objective We hypothesized that the (S)-enantiomer may counter the effects of the (R)-enantiomer, potentially increasing GM-CSF release. Therefore, the effects of administration of individual and combined enantiomers on GM-CSF release were examined.

METHODS

Cultured HASMCs were stimulated with IL-1beta, TNF-alpha, and IFN-gamma and treated with (R)-enantiomers and (S)-enantiomers of albuterol and formoterol, with and without propranolol and ICI-118,551, and in combination with dexamethasone. GM-CSF in the resulting conditioned media was assessed by ELISA.

RESULTS

(R)-enantiomers significantly reduced GM-CSF release by as much as 41% ( P < .05), which was reversible with propranolol. In contrast, (S)-enantiomers significantly increased GM-CSF release by as much as 34% ( P < .05) over release with no drug, and by 25% to 40% ( P < .05) when added with (R)-enantiomers. The decremental effect of dexamethasone was amplified by (R)-enantiomers but inhibited by (S)-enantiomers. Both propranolol and ICI-118,551 alone increased GM-CSF release in a concentration-dependent fashion, similar to (S)-enantiomers.

CONCLUSION

We conclude that GM-CSF release by HASMC is downregulated by (R)-enantiomers and enhanced by (S)-enantiomers. The reversal of (R)-enantiomer and dexamethasone effects by the (S)-enantiomer suggests suppression of their anti-inflammatory effects, perhaps through an antagonistic mechanism similar to propranolol.

Studies of the Biogenic Amine Transporters. XI. Identification of a 1-[2-[Bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR12909) Analog That Allosterically Modulates the Serotonin Transporter

Previous studies identified partial inhibitors of serotonin (5-HT) transporter and dopamine transporter binding. We report here on a partial inhibitor of 5-HT transporter (SERT) binding identified among a group of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine analogs (4-[2-[bis(4-fluorophenyl)-methoxy]ethyl]-1-(2-trifluoromethyl-benzyl)-piperidine; TB-1-099). Membranes were prepared from rat brains or human embryonic kidney cells expressing the cloned human dopamine (hDAT), serotonin (hSERT), and norepinephrine (hNET) transporters. beta-(4'-(125)Iodophenyl)tropan-2beta-carboxylic acid methyl ester ([(125)I]RTI-55) binding and other assays followed published procedures. Using rat brain membranes, TB-1-099 weakly inhibited DAT binding (K(i) = 439 nM), was inactive at NET binding ([(3)H]nisoxetine), and partially inhibited SERT binding with an extrapolated plateau ("A" value) of 20%. Similarly, TB-1-099 partially inhibited [(125)I]RTI-55 binding to hSERT with an extrapolated plateau (A value) of 14%. Upon examining the effect of increasing concentrations of TB-1-099 on the apparent K(d) and B(max) of [(125)I]RTI-55 binding to hSERT, we found that TB-1-099 decreased the B(max) in a dose-dependent manner and affected the apparent K(d) in a manner well described by a sigmoid dose-response curve. TB-1-099 increased the K(d) but not to the magnitude expected for a competitive inhibitor. In rat brain synaptosomes, TB-1-099 noncompetitively inhibited [(3)H]5-HT, but not [(3)H]dopamine, uptake. Dissociation experiments indicated that TB-1-099 promoted the rapid dissociation of a small component of [(125)I]RTI-55 binding to hSERT. Association experiments demonstrated that TB-1-099 slowed [(125)I]RTI-55 binding to hSERT in a manner unlike that of the competitive inhibitor indatraline. Viewed collectively, these results support the hypothesis that TB-1-099 allosterically modulates hSERT binding and function.

Superoxide dismutase inactivation in pathophysiology of asthmatic airway remodeling and reactivity

Airway hyperresponsiveness and remodeling are defining features of asthma. We hypothesized that impaired superoxide dismutase (SOD) antioxidant defense is a primary event in the pathophysiology of hyperresponsiveness and remodeling that induces apoptosis and shedding of airway epithelial cells. Mechanisms leading to apoptosis were studied in vivo and in vitro. Asthmatic lungs had increased apoptotic epithelial cells compared to controls as determined by terminal dUTP nick-end labeling-positive cells. Apoptosis was confirmed by the finding that caspase-9 and -3 and poly (ADP-ribose) polymerase were cleaved. On the basis that SOD inactivation triggers cell death and low SOD levels occur in asthma, we tested whether SOD inactivation plays a role in airway epithelial cell death. SOD inhibition increased cell death and cleavage/activation of caspases in bronchial epithelial cells in vitro. Furthermore, oxidation and nitration of MnSOD were identified in the asthmatic airway, correlating with physiological parameters of asthma severity. These findings link oxidative and nitrative stress to loss of SOD activity and downstream events that typify asthma, including apoptosis and shedding of the airway epithelium and hyperresponsiveness.

Enhanced nitric oxide production associated with airway hyporesponsiveness in the absence of IL-10

Interleukin (IL)-10 is an anti-inflammatory cytokine implicated in the regulation of airway inflammation in asthma. Among other activities, IL-10 suppresses production of nitric oxide (NO); consequently, its absence may permit increased NO production, which can affect airway smooth muscle contractility. Therefore, we investigated airway reactivity (AR) in response to methacholine (MCh) in IL-10 knockout (-/-) mice compared with wild-type C57BL/6 (C57) mice, in which airway NO production was measured as exhaled NO (E(NO)), and NO production was altered with administration of either NO synthase (NOS)-specific inhibitors or recombinant murine (rm)IL-10. AR, measured as enhanced pause in vivo, and tracheal ring tension in vitro were lower in IL-10(-/-) mice by 25-50%, which was associated with elevated E(NO) levels (13 vs. 7 ppb). Administration of NOS inhibitors N(G)-nitro-L-arginine methyl ester (8 mg/kg ip) or L-N(6)-(1-iminoethyl)-lysine (3 mg/kg ip) to IL-10(-/-) mice decreased E(NO) by an average of 50%, which was associated with increased AR, to levels similar to C57 mice. E(NO) in IL-10(-/-) mice decreased in a dose-dependent fashion in response to administered rmIL-10, to levels similar to C57 mice (7 ppb), which was associated with a 30% increment in AR. Thus increased NO production in the absence of IL-10, decreased AR, which was reversed with inhibition of NO, either by inhibition of NOS, or with reconstitution of IL-10. These findings suggest that airway NO production can modulate airway smooth muscle contractility, resulting in airway hyporesponsiveness when IL-10 is absent.