A Design of Experiment (DoE) approach to optimise spray drying process conditions for the production of trehalose/leucine formulations with application in pulmonary delivery

The present study evaluates the effect of L-leucine concentration and operating parameters of a laboratory spray dryer on characteristics of trehalose dry powders, with the goal of optimizing production of these powders for inhaled drug delivery. Trehalose/L-leucine mixtures were spray dried from aqueous solution using a laboratory spray dryer. A factorial design of experiment (DoE) was undertaken and process parameters adjusted were: inlet temperature, gas flow rate, feed solution flow rate (pump setting), aspiration setting and L-leucine concentration. Resulting powders were characterised in terms of particle size, yield, residual moisture content, and glass transition temperature. Particle size was mainly influenced by gas flow rate, whereas product yield and residual moisture content were found to be primarily affected by inlet temperature and spray solution feed rate respectively. Interactions between a number of different process parameters were elucidated, as were relationships between different responses. The leucine mass ratio influenced the physical stability of powders against environmental humidity, and a high leucine concentration (30% w/w) protected amorphous trehalose from moisture induced crystallization. High weight ratio of leucine in the formulation, however, negatively impacted the aerosol performance. Thus, in terms of L-leucine inclusion in a formulation designed for pulmonary delivery, a balance needs to be found between physical stability and deposition characteristics.

Corticosteroid and long-acting ß-agonist therapy reduces epithelial goblet cell metaplasia

BACKGROUND

Bronchial epithelial goblet cell metaplasia (GCM) with hyperplasia is a prominent feature of asthma, but the effects of treatment with corticosteroids alone or in combination with a long-acting β₂ -adrenergic receptor agonist (LABA) on GCM in the bronchial epithelium are unknown.

OBJECTIVES

To determine whether corticosteroid alone or in combination with a LABA alters protein and gene expression pathways associated with IL-13-induced goblet cell metaplasia.

RESULTS

We evaluated the effects of fluticasone propionate (FP) and of salmeterol (SM), on the response of well-differentiated cultured bronchial epithelial cells to interleukin-13 (IL-13). Outcome measures included gene expression of SPDEF/FOXa2, gene expression and protein production of MUC5AC/MUC5B and morphologic appearance of cultured epithelial cell sheets. We additionally analysed expression of these genes in bronchial epithelial brushings from healthy, steroid-naïve asthmatic and steroid-treated asthmatic subjects. In cultured airway epithelial cells, FP treatment inhibited IL-13-induced suppression of FOXa2 gene expression and up-regulation of SPDEF, alterations in gene and protein measures of MUC5AC and MUC5B and induction of GCM. The addition of SM synergistically modified the effects of FP modestly-only for gel-forming mucin MUC5AC. In bronchial epithelial cells recovered from asthmatic vs healthy human subjects, we found FOXa2 and MUC5B gene expression to be reduced and SPDEF and MUC5AC gene expression to be increased; these alterations were not observed in bronchial epithelial cells recovered after treatment with inhaled corticosteroids.

CONCLUSION AND CLINICAL RELEVANCE

Corticosteroid treatment inhibits IL-13-induced GCM of the airways in asthma, possibly through its effects on SPDEF and FOXa2 regulation of mucin gene expression. These effects are modestly augmented by the addition of a long-acting ß-agonist. As we found evidence for drug treatment counteracting the effects of IL-13 on the epithelium, we conclude that further exploration into the mechanisms by which corticosteroids and long-acting β₂ -adrenergic agonists confer protection against pathologic airway changes is warranted.

A protective role for periostin and TGF-β in IgE-mediated allergy and airway hyperresponsiveness

Background

The pathophysiology of asthma involves allergic inflammation and remodelling in the airway and airway hyperresponsiveness (AHR) to cholinergic stimuli, but many details of the specific underlying cellular and molecular mechanisms remain unknown. Periostin is a matricellular protein with roles in tissue repair following injury in both the skin and heart. It has recently been shown to be up-regulated in the airway epithelium of asthmatics and to increase active TGF-β. Though one might expect periostin to play a deleterious role in asthma pathogenesis, to date its biological role in the airway is unknown.

Objective

To determine the effect of periostin deficiency on airway responses to inhaled allergen.

Methods

In vivo measures of airway responsiveness, inflammation, and remodelling were made in periostin deficient mice and wild-type controls following repeated intranasal challenge with Aspergillus fumigatus antigen. In vitro studies of the effects of epithelial cell-derived periostin on murine T cells were also performed.

Results

Surprisingly, compared with wild-type controls, periostin deficient mice developed increased AHR and serum IgE levels following allergen challenge without differences in two outcomes of airway remodelling (mucus metaplasia and peribronchial fibrosis). These changes were associated with decreased expression of TGF-β1 and Foxp3 in the lungs of periostin deficient mice. Airway epithelial cell-derived periostin-induced conversion of CD4⁺ CD25⁻ cells into CD25⁺, Foxp3⁺ T cells in vitro in a TGF-β dependent manner.

Conclusions and Clinical Relevance

Allergen-induced increases in serum IgE and bronchial hyperresponsiveness are exaggerated in periostin deficient mice challenged with inhaled aeroallergen. The mechanism of periostin's effect as a brake on allergen-induced responses may involve augmentation of TGF-β-induced T regulatory cell differentiation.

Negative methacholine challenge tests in subjects who report physician-diagnosed asthma

BACKGROUND

The frequency of adults reporting a history of asthma is rising. However, it is unclear whether this increased prevalence accurately demonstrates a rising trend or if it reflects an overall increase in asthma awareness.

OBJECTIVE

To determine the frequency of negative methacholine bronchoprovocation tests in adults who report physician-diagnosed asthma and to explore the clinical characteristics of subjects with negative tests.

METHODS

Data from methacholine challenge, spirometry, and physician assessment were analysed from 304 adults who reported physician-diagnosed asthma and responded to community-based advertising for asthma research studies. The clinical characteristics of methacholine-positive and -negative subjects were compared and a predictive model was tested to identify those characteristics associated with a negative test.

RESULTS

Of the 304 subjects tested, 83 (27%) had a negative methacholine test. A negative test was positively associated with an adult-onset of symptoms (P<0.001), normal forced expiratory volume in 1 s (P<0.001), and having no history of exacerbation requiring oral steroids (P=0.03). Over half (60%) of those with a negative test reported weekly asthma-like symptoms (cough, dyspnoea, chest tightness, or wheeze), while 39% reported emergency department visits for asthma-like symptoms.

CONCLUSIONS AND CLINICAL RELEVANCE

A sizeable percentage of subjects who report physician-diagnosed asthma have a negative methacholine challenge test. These subjects are characterized by diagnosis of asthma as an adult and by normal or near normal spirometry. Caution should be exercised in the assessment and diagnosis of adults presenting with asthma-like symptoms, because they may not have asthma. Further diagnostic studies, including bronchoprovocation testing, are warranted in this patient group, especially if their spirometry is normal.

Acute exacerbations of asthma: epidemiology, biology and the exacerbation-prone phenotype

Asthma is a highly prevalent chronic respiratory disease affecting 300 million people world-wide. A significant fraction of the cost and morbidity of asthma derives from acute care for asthma exacerbations. In the United States alone, there are approximately 15 million outpatient visits, 2 million emergency room visits, and 500,000 hospitalizations each year for management of acute asthma. Common respiratory viruses, especially rhinoviruses, cause the majority of exacerbations in children and adults. Infection of airway epithelial cells with rhinovirus causes the release of pro-inflammatory cytokines and chemokines, as well as recruitment of inflammatory cells, particularly neutrophils, lymphocytes, and eosinophils. The host response to viral infection is likely to influence susceptibility to asthma exacerbation. Having had at least one exacerbation is an important risk factor for recurrent exacerbations suggesting an 'exacerbation-prone' subset of asthmatics. Factors underlying the 'exacerbation-prone' phenotype are incompletely understood but include extrinsic factors: cigarette smoking, medication non-compliance, psychosocial factors, and co-morbidities such as gastroesophageal reflux disease, rhinosinusitis, obesity, and intolerance to non-steroidal anti-inflammatory medications; as well as intrinsic factors such as deficient epithelial cell production of the anti-viral type I interferons (IFN-alpha and IFN-beta). A better understanding of the biologic mechanisms of host susceptibility to recurrent exacerbations will be important for developing more effective preventions and treatments aimed at reducing the significant cost and morbidity associated with this important global health problem.

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.

Effect of a single dose of the selectin inhibitor TBC1269 on early and late asthmatic responses

BACKGROUND

Selectins participate in the initial phase of leucocyte migration from circulation to inflamed tissues and may play a role in inflammatory cellular influx into airways in asthma. In the sheep asthma model, TBC1269, a pan-selectin antagonist, reduced late allergen response by 74%.

OBJECTIVE

To determine whether a single dose of TBC1269 inhibits early (EAR) and late (LAR) asthmatic responses, and whether it inhibits sputum leucocyte influx after inhalation allergen challenge in atopic asthmatic subjects treated with bronchodilators only.

METHODS

Twenty-one asthmatic subjects (mean+/-SD, age=32.5+/-6.7 years, 8 males, FEV1 percent predicted=84+/-15%) with known late asthmatic response based on a screening inhalation allergen challenge were randomly assigned to receive intravenous treatment with either placebo (n=11) or TBC1269 (n=10, 30 mg/kg) infused over 15 min immediately prior to a second (post-treatment) allergen challenge at least 4 weeks after the screening challenge. After each challenge, EAR and LAR were monitored for 7 h. In addition, sputum was induced 1 day before and 1 day after each allergen challenge.

RESULTS

TBC1269 did not attenuate the EAR compared with placebo (largest fall in FEV1 within 1 h of 34.1+/-13.9% vs. 31.8+/-12.2% for TBC1269 and placebo groups respectively, P=0.61) or the LAR (largest fall in FEV1 between 3 and 7 h of 39.3+/-15.3% vs. 32.6+/-13.8%, P=0.24). TBC1269 had only minor effects on allergen-induced sputum eosinophilia.

CONCLUSION

We conclude that TBC1269 administered before allergen challenge as a single intravenous dose does not attenuate early or late asthmatic responses to allergen in asthmatic subjects.

Remodeling of the airway epithelium in asthma

Several pathologic changes occur in the airway epithelium in asthma, but the relationship between these changes and the initiation and progression of asthma remains poorly understood. One possibility is that changes in the structure and function of the epithelium induced by environmental exposure in genetically susceptible subjects represent primary pivotal events that occur early in the pathogenesis of asthma. Alternatively, these epithelial changes may occur simply as a consequence of pivotal early events in other systems, such as immune deviation in childhood to a helper T cell type 2 (Th2) subtype of CD4(+) cells. Epithelial desquamation in asthma represents a pathologic change that is frequently cited as important for the mechanisms of airway remodeling and airway hyperresponsiveness. Desquamation of the epithelium may not represent true pathology, however, but may instead be an artifact of tissue sampling and handling. Evidence is more firm for other pathologic changes in the epithelium. For example, goblet cell numbers are increased in asthma, leading to increases in stored mucins in the epithelium and in secreted mucins in sputum. The functional consequences of these changes include sputum production and airway narrowing, which lead to asthma exacerbations. Currently available data suggest that an important mechanism for goblet cell hyperplasia in asthma is the action of Th2 cytokines. Improved understanding of epithelial goblet cell abnormalities in asthma will hopefully lead to novel therapies for mucin hypersecretion, which is an important cause of morbidity and mortality.

Allergen challenge causes inflammation but not goblet cell degranulation in asthmatic subjects

BACKGROUND

An allergen challenge to the airways of sensitized mice causes eosinophilic airway inflammation and degranulation of goblet cells, which lead to airway obstruction. However, whether allergen challenge causes a similar pattern of airway inflammation and goblet cell degranulation in human beings is unknown.

OBJECTIVE

The purpose of this study was to determine whether allergen challenge increases airway inflammatory cells and causes goblet cell degranulation in human subjects with asthma.

METHODS

In bronchial biopsy specimens taken from 8 asthmatic subjects at 1 and 24 hours after allergen challenge, we measured eosinophil and neutrophil numbers as indicators of inflammation. We also measured goblet cell mucin stores and the amounts of secreted mucin in bronchial lavage as indicators of goblet cell degranulation.

RESULTS

Airway eosinophil numbers at both 1 and 24 hours after allergen challenge were twice as high as those after diluent challenge. Changes in neutrophil numbers were smaller and statistically insignificant. Goblet cell mucin stores measured in tissue stained with alcian blue/periodic acid-Schiff did not decrease significantly from baseline to 1 hour and actually tended to increase at 24 hours. This increase was significant in the subgroup of subjects with normal stored mucin levels at baseline. Mucin-like glycoprotein concentrations in bronchial lavage did not change significantly at either time point.

CONCLUSION

Although allergen challenge in asthmatic subjects increases airway eosinophil numbers as early as 1 hour after challenge, this inflammatory response does not cause goblet cell degranulation. In fact, in subjects with normal baseline mucin stores, allergen challenge increases goblet cell mucin stores.

Relationship between airway inflammation, hyperresponsiveness, and obstruction in asthma

BACKGROUND

Although the role of eosinophils in airway inflammation in chronic asthma has been extensively studied, a role for neutrophils has not been well characterized. Furthermore, prior studies have not systematically sought or controlled for factors that might confound the relationship between cellular markers of inflammation and physiologic measures of airway function.

OBJECTIVE

The purpose of this study was to determine whether eosinophilic and neutrophilic inflammation independently contribute to abnormalities of airway function in asthma.

METHODS

Multivariate analysis of data collected during screening and enrollment of 205 asthmatic adults for clinical trials was conducted to examine the relationships between cellular inflammation in induced sputum and FEV(1) and methacholine responsiveness (PC(20)) while confounding factors were controlled for.

RESULTS

We found that age, sex, ethnicity, and use of inhaled corticosteroids were important confounding factors of the relationship between cellular inflammation and airway function. When these factors were controlled for, multivariate analysis showed that eosinophil percentage in induced sputum is independently associated with lower FEV(1) and lower PC(20) (P = .005 and P = .005, respectively). In the same models, increased sputum neutrophil percentage is independently associated with lower FEV(1) (P = .038) but not with PC(20) (P = .49).

CONCLUSIONS

These results suggest that both eosinophilic inflammation and neutrophilic inflammation independently contribute to abnormalities of FEV(1) in asthma. Therapies directed specifically at control of neutrophilic inflammation might be useful in improving airway caliber in patients with chronic asthma.

A novel method of gene transcript profiling in airway biopsy homogenates reveals increased expression of a Na+-K+-Cl- cotransporter (NKCC1) in asthmatic subjects

Comprehensive and systematic analysis of airway gene expression represents a strategy for addressing the multiple, complex, and largely untested hypotheses that exist for disease mechanisms, including asthma. Here, we report a novel real-time PCR-based method specifically designed for quantification of multiple low-abundance transcripts using as little as 2.5 fg of total RNA per gene. This method of gene expression profiling has the same specificity and sensitivity as RT-PCR and a throughput level comparable to low-density DNA microarray hybridization. In this two-step method, multiplex RT-PCR is successfully combined with individual gene quantification via real-time PCR on generated cDNA product. Using this method, we measured the expression of 75 genes in bronchial biopsies from asthmatic versus healthy subjects and found expected increases in expression levels of Th2 cytokines and their receptors in asthma. Surprisingly, we also found increased gene expression of NKCC1--a Na+-K+-Cl- cotransporter. Using immunohistochemical method, we confirmed increased protein expression for NKCC1 in the asthmatic subject with restricted localization to goblet cells. These data validate the new transcriptional profiling method and implicate NKCC1 in the pathophysiology of mucus hypersecretion in asthma. Potential applications for this method include transcriptional profiling in limited numbers of laser captured cells and validation of DNA microarray data in clinical specimens.

Safety and reproducibility of sputum induction in asthmatic subjects in a multicenter study

The safety of sputum induction and the reproducibility of measurements in induced sputum in multicenter studies is unknown. We examined the safety of sputum induction in a two-visit, six-center study in 79 subjects with moderate to severe asthma (mean +/- SD FEV(1) 71 +/- 12% predicted, 67% taking inhaled corticosteroids). In addition, we compared the reproducibility of markers of inflammation in induced sputum with the reproducibility of the FEV(1) and the methacholine PC(20). The FEV(1) decreased > or = 20% from the postbronchodilator baseline in 14% of all subjects and in 25% of subjects whose initial prebronchodilator baseline was 40 to 60% of predicted. All subjects responded promptly to additional albuterol treatment, and no subject developed refractory bronchoconstriction requiring treatment other than reversal of bronchospasm in the study laboratory. The reproducibility of measurements of the eosinophil percentage, eosinophil cationic protein, tryptase, and methacholine PC(20) were similar (concordance correlation coefficients of 0.74, 0.81, 0.79, and 0.74, respectively), without any significant among-center effect. We conclude that sputum induction can be performed safely in subjects with moderate to severe asthma in multicenter clinical trials when carried out under carefully monitored conditions. Importantly, we demonstrate that measurement of markers of inflammation in induced sputum is as reproducible as methacholine PC(20) and should prove useful in the assessment of airway inflammation in multicenter clinical trials.

Inhaled corticosteroid reduction and elimination in patients with persistent asthma receiving salmeterol: a randomized controlled trial

CONTEXT

Inhaled long-acting beta(2)-agonists improve asthma control when added to inhaled corticosteroid (ICS) therapy.

OBJECTIVE

To determine whether ICS therapy can be reduced or eliminated in patients with persistent asthma after adding a long-acting beta(2)-agonist to their treatment regimen.

DESIGN AND SETTING

A 24-week randomized, controlled, blinded, double-dummy, parallel-group trial conducted at 6 National Institutes of Health-sponsored, university-based ambulatory care centers from February 1997 through January 1999.

PARTICIPANTS

One hundred seventy-five patients aged 12 through 65 years with persistent asthma that was suboptimally controlled during a 6-week run-in period of treatment with inhaled triamcinolone acetonide (400 microg twice per day).

INTERVENTION

Patients continued triamcinolone therapy and were randomly assigned to receive add-on therapy with either placebo (placebo-minus group, n = 21) or salmeterol xinafoate, 42 microg twice per day (n = 154) for 2 weeks. The entire placebo-minus group was assigned and half of the salmeterol group (salmeterol-minus group) was randomly assigned to reduce by 50% (for 8 weeks) then eliminate (for 8 weeks) triamcinolone treatment. The other half of the salmeterol group (salmeterol-plus group) was randomly assigned to continue both salmeterol and triamcinolone for the remaining 16 weeks (active control group).

MAIN OUTCOME MEASURE

Time to asthma treatment failure in patients receiving salmeterol.

RESULTS

Treatment failure occurred in 8.3% (95% confidence interval [CI], 2%-15%) of the salmeterol-minus group 8 weeks after triamcinolone treatment was reduced compared with 2.8% (95% CI, 0%-7%) of the salmeterol-plus group during the same period. Treatment failure occurred in 46.3% (95% CI, 34%-59%) of the salmeterol-minus group 8 weeks after triamcinolone therapy was eliminated compared with 13.7% (95% CI, 5%-22%) of the salmeterol-plus group. The relative risk (95% CI) of treatment failure at the end of the triamcinolone elimination phase in the salmeterol-minus group was 4.3 (2.0-9.2) compared with the salmeterol-plus group (P<.001).

CONCLUSIONS

Our results indicate that in patients with persistent asthma suboptimally controlled by triamcinolone therapy alone but whose asthma symptoms improve after addition of salmeterol, a substantial reduction (50%) in triamcinolone dose can occur without a significant loss of asthma control. However, total elimination of triamcinolone therapy results in a significant deterioration in asthma control and, therefore, cannot be recommended.

Long-acting beta2-agonist monotherapy vs continued therapy with inhaled corticosteroids in patients with persistent asthma: a randomized controlled trial

CONTEXT

Long-acting beta(2)-agonists are prescribed for patients with persistent asthma and are sometimes used without inhaled corticosteroids (ICSs). No evidence exists, however, to support their use as monotherapy in adults with persistent asthma.

OBJECTIVE

To examine the effectiveness of salmeterol xinafoate, a long-acting beta(2)-agonist, as replacement therapy in patients whose asthma is well controlled by low-dose triamcinolone acetonide, an ICS.

DESIGN AND SETTING

A 28-week, randomized, blinded, placebo-controlled, parallel group trial conducted at 6 National Institutes of Health-sponsored, university-based ambulatory care centers from February 1997 to January 1999.

PARTICIPANTS

One hundred sixty-four patients aged 12 through 65 years with persistent asthma that was well controlled during a 6-week run-in period of treatment with inhaled triamcinolone (400 microg twice per day).

INTERVENTIONS

Patients were randomly assigned to continue triamcinolone therapy (400 microg twice per day; n = 54) or switch to salmeterol (42 microg twice per day; n = 54) or to placebo (n = 56) for 16 weeks, after which all patients received placebo for an additional 6-week run-out period.

MAIN OUTCOME MEASURES

Change in morning and evening peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV(1)), self-assessed asthma symptom scores, rescue albuterol use, asthma-specific quality-of-life scores, treatment failure, asthma exacerbation, bronchial reactivity, and markers of airway inflammation, compared among the 3 treatment groups.

RESULTS

During the 16-week randomized treatment period, no significant differences between the salmeterol and triamcinolone groups were observed for conventional outcomes of clinical studies of asthma therapy-morning PEF, evening PEF, asthma symptom scores, rescue albuterol sulfate use, or quality of life. Both active treatments were superior to placebo. However, the salmeterol group had more treatment failures than the triamcinolone group (13/54 [24%] vs 3/54 [6%]; P =.004), as well as more asthma exacerbations (11/54 [20%] vs 4/54 [7%]; P =.04), greater increases in median (interquartile range) sputum eosinophils (2.4% [0.0% to 10.6%] vs -0.1% [-0.7% to 0.3%]; P<.001), eosinophil cationic protein (71 [-2 to 430] U/L vs -4 [-31 to 56] U/L; P =.005), and tryptase (3.1 [2.1 to 7.6] ng/mL vs 0.0 [0.0 to 0.7] ng/mL; P<.001). The duration of benefit when patients were switched from active treatment to placebo after 22 weeks of randomized treatment was not significantly longer in the triamcinolone group than in the salmeterol group.

CONCLUSIONS

Patients with persistent asthma well controlled by low doses of triamcinolone cannot be switched to salmeterol monotherapy without risk of clinically significant loss of asthma control.

The utility of peak flow, symptom scores, and beta-agonist use as outcome measures in asthma clinical research

STUDY OBJECTIVES

Several methods of utilizing peak expiratory flow (PEF) and other markers of disease activity have been suggested as useful in the management of asthma. It remains unclear, however, as to which surrogate markers of disease status are discriminative indicators of treatment failure, suitable for use in clinical trials.

DESIGN

We analyzed the operating characteristics of 66 surrogate markers of treatment failure using a receiver operating characteristic (ROC) curve analysis.

PARTICIPANTS

Information regarding FEV(1), symptoms, beta(2)-agonist use, and PEF was available from 313 subjects previously enrolled in two Asthma Clinical Research Network trials, in which 71 treatment failures occurred (defined by a 20% fall in FEV(1) from baseline).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

None of the measures had an acceptable ability to discriminate subjects with a > or % fall in FEV(1) from those without, regardless of the duration of the period of analysis or the criteria for test positivity employed. Areas under the ROC curves generated ranged from 0.51 to 0.79, but none were statistically superior. Sensitivity and specificity combinations were generally poor at all cutoff values; true-positive rates could not be raised without unacceptably elevating false-positive rates concurrently.

CONCLUSIONS

Studies that seek to detect treatment failure defined by a significant fall in FEV(1) should not use such individual surrogate measures to estimate disease severity.

Mild and moderate asthma is associated with airway goblet cell hyperplasia and abnormalities in mucin gene expression

Excessive airway mucus is an important cause of morbidity and mortality in asthma, but the relationship between accumulation of mucus and goblet cell size, number, and function is incompletely understood. To address these questions, stored mucin in the epithelium and goblet cell size and number were measured morphometrically, and mucin gene expression was measured by polymerase chain reaction and immunohistochemistry in endobronchial biopsies from 13 subjects with mild and moderate asthma and from 12 healthy control subjects. Secreted mucin was measured in induced sputum. We found that stored mucin in the airway epithelium was three times higher than normal in the subjects with asthma (p < 0.005). Goblet cell size was similar in both groups, but goblet cell number was significantly higher in the subjects with asthma (93,043 +/- 15,824 versus 41,959 +/- 9,230/mm3, p < 0.05). In mild asthma (FEV1 > or = 80% pred, n = 7), the level of stored mucin was as high as in moderate asthma (FEV1 < 80% pred, n = 6), but the level of secreted mucin was significantly lower (28.4 +/- 6.3 versus 73.5 +/- 47.5 microg/ml, p < 0.05). Secreted mucin was inversely correlated with stored mucin for the whole asthma group (rs = -0.78, p = 0.007). MUC5AC was the predominant mucin gene expressed in healthy subjects and subjects with asthma, and MUC5AC protein was increased in the subjects with asthma. We conclude that even mild asthma is associated with goblet cell hyperplasia and increased stored mucin in the airway epithelium, whereas moderate asthma is associated with increased stored mucin and secreted mucin. These findings suggest that acute degranulation of hyperplastic goblet cells may represent a mechanism for asthma exacerbations in mild and moderate asthma and that chronic degranulation of goblet cells may contribute to chronic airway narrowing in moderate asthma.

Relationship of epidermal growth factor receptors to goblet cell production in human bronchi

To determine the relationship of epidermal growth factor receptor (EGFR) expression to mucin synthesis in human airways, we examined EGFR and MUC5AC expression at both gene and protein levels using in situ hybridization and immunohistochemical analysis in human bronchi. Bronchial mucosal biopsy specimens were obtained from 12 asthmatic subjects and 11 healthy subjects. In asthmatic airways, EGFR mRNA was expressed in the airway epithelium. EGFR immunoreactivity staining patterns varied among the asthmatic airways: staining was positive mainly in goblet cells, in basal cells, or in both. In contrast, healthy airways showed little expression of EGFR mRNA; EGFR immunoreactivity was observed mainly in goblet cells. In parallel to EGFR expression, MUC5AC mRNA expression was greater in asthmatic airways; mucous glycoconjugates that stained positively with Alcian blue/PAS were also increased in asthmatic airways. Ciliated cells were negative for EGFR and MUC5AC both in asthmatic and in healthy subjects at both mRNA and protein levels. There was a significant positive correlation between EGFR immunoreactivity and the area of MUC5AC-positive staining in both asthmatics and healthy subjects. These findings suggest a sequence of events by which EGFR activation is involved in mucin expression in asthmatic airway epithelium.

Effect of polymorphism of the beta(2)-adrenergic receptor on response to regular use of albuterol in asthma

BACKGROUND

Regular use of inhaled beta-adrenergic agonists may have adverse effects in some asthma patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect its regulation; however, results of smaller studies of the effects of such polymorphisms on response to beta-agonist therapy have been inconsistent.

METHODS

We examined the possible effects of polymorphisms at codons 16 (beta(2)-AR-16) and 27 (beta(2)-AR-27) on response to albuterol by genotyping 190 asthmatics who had participated in a trial of regular versus as-needed albuterol use.

RESULTS

During the 16-week treatment period, patients homozygous for arginine (Arg/Arg) at beta(2)-AR-16 who used albuterol regularly had a small decline in morning peak expiratory flow (AM PEF). This effect was magnified during a 4-week run-out period, when all patients returned to as-needed albuterol only. By the end of the study, Arg/Arg subjects who had used albuterol regularly had an AM PEF 30.5 +/- 12.1 liters/min lower (p = 0.012) than Arg/Arg patients who had used albuterol as needed only. Subjects homozygous for glycine at beta(2)-AR-16 showed no such decline. Evening PEF also declined in the Arg/Arg regular but not in as-need albuterol users. No significant differences between regular and as-needed treatment were associated with polymorphisms at beta(2)-AR-27.

CONCLUSIONS

Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

Epithelial desquamation in asthma: artifact or pathology?

To determine whether the denudation of the bronchial epithelium observed in endobronchial biopsies from asthmatic subjects is a true pathologic feature or an artifact of tissue sampling, we analyzed epithelial integrity in bronchial biopsies from 14 subjects with mild and moderate asthma and 12 healthy subjects. In each subject, 4 to 8 bronchial biopsies were taken from large airways during bronchoscopy, fixed in 4% paraformaldehyde, embedded in glycomethacrylate, cut into 2-microM sections, and stained with toluidine blue. A x4 image of each biopsy was copied to a computer file using a video camera, and lines were drawn and measured along the basement membrane underlying areas completely denuded of overlying epithelium, areas covered by a single layer of basal cells, and areas of intact epithelium. We found that the percentage of basement membrane that was denuded of epithelium was similar in the healthy and asthmatic subjects (14.8 +/- 11.8 versus 11.4 +/- 9.8% respectively, p = 0.38); the percentage of basement membrane that was covered by a single layer of basal cells was also similar in the two groups (46.4 +/- 11.0 versus 54.5 +/- 9.8%, respectively, p = 0. 11). In the asthmatic subjects, we found no significant correlation between the percentage of basement membrane covered by denuded epithelium or by a single layer of basal cells and the FEV(1) percentage of predicted or the PC(20) methacholine. We conclude that denudation of bronchial epithelium in endobronchial biopsies from asthmatic subjects with stable mild and moderate disease is an artifact of tissue sampling and is not a true pathologic feature of the disease, and that the extent of airway epithelial denudation is not correlated with the severity of airway narrowing or the severity of bronchial hyperresponsiveness.

The effect of polymorphisms of the beta(2)-adrenergic receptor on the response to regular use of albuterol in asthma

Inhaled beta-adrenergic agonists are the most commonly used medications for the treatment of asthma although there is evidence that regular use may produce adverse effects in some patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect regulation of the receptor. Smaller studies examining the effects of such polymorphisms on the response to beta-agonist therapy have produced inconsistent results. We examined whether polymorphisms at codon 16 (beta(2)-AR-16) and codon 27 (beta(2)-AR-27) of the beta(2)-AR might affect the response to regular versus as-needed use of albuterol by genotyping the 190 asthmatics who had participated in a trial examining the effects of regular versus as needed albuterol use. During the 16-wk treatment period there was a small decline in morning peak expiratory flow in patients homozygous for arginine at B(2)-AR-16 (Arg/Arg) who used albuterol regularly. This effect was magnified during a 4-wk run out period, during which all patients returned to using as-needed albuterol, so that by the end of the study Arg Arg patients who had regularly used albuterol had a morning peak expiratory flow 30. 5 +/- 12.1 L/min lower (p = 0.012) than Arg/Arg patients who had used albuterol on an as needed basis. There was no decline in peak flow with regular use of albuterol in patients who were homozygous for glycine at beta(2)-AR-16. Evening peak expiratory flow also declined in the Arg/Arg patients who used albuterol regularly but not in those who used albuterol on an as-needed basis. No significant differences in outcomes between regular and as-needed treatment were associated with polymorphisms at position 27 of the beta(2)-AR. No other differences in asthma outcomes that we investigated occurred in relation to these beta(2)-AR polymorphisms. Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

Reducing IgE levels as a strategy for the treatment of asthma

IgE secretion by B lymphocytes defines the allergic state and nearly all asthmatics have higher than normal IgE levels in serum following adjustment for age and sex. It is thought that allergic mechanisms may be responsible for the increasing prevalence of asthma. In particular, in utero changes may encourage T cells to differentiate into Th2 subtypes. Th2 cells produce cytokines such as IL-4 and IL-5, which can act indirectly via B cells, mast cells and eosinophils to mediate the asthma phenotype. Alternatively, IL-4 and IL-13 may act directly on the airway. Th2 lymphocyte inflammation in asthma predisposes subjects to B cell and IgE-mediated airway inflammation. IgE binds to receptors on the surface of a variety of effector cells causing them to release a variety of mediators that promote airway hyperresponsiveness, mucus secretion and increased vascular permeability. Several strategies for decreasing IgE have been developed as a possible treatment for asthma. For example, anti-IgE monoclonal antibodies such as rhuMAb-E25 and CGP 56901 block binding of IgE to its high-affinity receptor and have been shown to reduce IgE levels in humans without causing anaphylaxis. IgE levels must be nearly completely suppressed. Recent clinical studies in subjects with asthma have shown that rhuMAb-E25 attenuates both the early and late phase responses to inhaled allergen, and reduces the associated increase in eosinophils in induced sputum. rhuMAb-E25 is well tolerated and has shown promising results in improving symptoms and lung function in patients with moderate to severe asthma. Other strategies for decreasing IgE levels include interferon gamma, IL-4 antibodies, IL-4 receptor antibodies and soluble IL-4 receptors.

Predictors of late asthmatic response. Logistic regression and classification tree analyses

To identify predictors of the late asthmatic response (LAR), we reviewed data from 60 asthmatic subjects who had undergone allergen challenge over the past 5 yr (33 females, age 31.4 +/- 6.7 yr [mean +/- SD], FEV(1) 90% +/- 14% predicted). Variables considered likely predictors of LAR included baseline FEV(1), PC(20) methacholine (PC(20)), sputum eosinophil percent, and the decrease in FEV(1) within 20 min of allergen challenge. A LAR (FEV(1) >/= 15% fall between 3 and 7 h after challenge) was documented in 57% of subjects. A variety of logistic regression methods revealed a significant inverse association between LAR and PC(20) (odds ratio [OR] = 0.14 [95% CI = 0.03-0.66]) and a positive association between LAR and the decrease in FEV(1) at 20 min (OR = 1.18 [1.04 -1.33]). Classification tree analysis revealed that a threshold of 0.25 mg/ml for PC(20) was most predictive of LAR; LAR developed in 87% of those with PC(20) </= 0.25 mg/ml (n = 23) and in 38% of those with PC(20) > 0.25 mg/ml (n = 37). Notably, in subjects with PC(20) > 0.25 mg/ml, the incidence of LAR increased from 38% to 57% if the allergen-induced decline in FEV(1) at 20 min was >/= 27%. Surprisingly, baseline FEV(1) and percent eosinophils in induced sputum were not significantly associated with LAR. We conclude that a threshold value of 0.25 mg/ml for PC(20) methacholine is a good predictor of LAR. Measuring the PC(20) methacholine may be useful as a screening method to improve the efficiency of identifying asthmatic subjects with a LAR.

Increased neutrophil numbers and IL-8 levels in airway secretions in acute severe asthma: Clinical and biologic significance

The inflammatory events in the airways at the time of acute respiratory failure from acute severe asthma are poorly understood. To determine the patterns of cellular inflammation in the airways in acute severe asthma, we analyzed tracheal aspirates collected within 12 h of intubation from patients intubated emergently for acute severe asthma (n = 10) and from patients intubated electively for nonpulmonary surgery (n = 14). The number of neutrophils in tracheal aspirates from asthma patients was 10 times higher than normal (4.2 [0.6 to 335.0] [median, range] versus 0.4 [0.009 to 9.4] x 10(6)/ml, p = 0.001), and there was a strong trend for a positive relationship between neutrophil number and duration of intubation (r(s) = 0.64, p = 0.06). Although eosinophil numbers were also significantly higher than normal (0.5 [0.0 to 23.3] versus 0.0 [0.0 to 0.1] x 10(6)/ml, p = 0.003), the numbers of eosinophils were 8-fold less than neutrophils, and there was no significant correlation between eosinophil number and duration of intubation (r(s) = 0.4, p = 0.26). Interleukin-8 (IL-8), a chemoattraction for neutrophils, was 19 times higher than normal in tracheal aspirates from asthmatic patients (75.0 [9.0 to 168.0] versus 4.0 [0.08 to 24.0] ng/ml, p < 0. 05) and correlated significantly with the neutrophil number (r(s) = 0.77, p = 0.03). Furthermore, the IL-8 levels correlated positively with the duration of mechanical ventilation (r(s) = 0.74, p = 0.03). Surprisingly, the number of neutrophils increased significantly during the period of intubation in the asthmatic subjects, possibly because of intravenous corticosteroid treatment. We conclude that neutrophils are the dominant inflammatory leukocyte characterizing airway inflammation in acute severe asthma that requires mechanical ventilation, and that IL-8 is an important mediator of this neutrophilia.

Low- and high-dose fluticasone propionate in asthma; effects during and after treatment

The dose dependency of the effects of inhaled corticosteroids on markers of asthmatic airway inflammation have not been well studied. There is a need to study the dose/response effects on this inflammation. In order to determine the dose/response effects of fluticasone propionate (FP), 24 asthmatic subjects were randomized to low- (100 microg x day(-1)) or high-dose (1,000 microg x day(-1)) FP for six weeks followed by placebo for 3 weeks. During treatment, the median increase in forced expiratory volume in one second (FEV1)was 12% in the high-dose group (p<0.05) and 10% in the low-dose group (p<0.05) (p>0.05 between groups); the median decrease in the percentage of sputum eosinophils was 93% in the high-dose group (p<0.05) and 46% in the low-dose group (p<0.05) (p>0.05 between groups). Symptoms, salbutamol use, morning peak flow, provocative concentration of methacholine causing a 20% fall in FEV1 (PC20), sputum eosinophil cationic protein concentration and tryptase activity improved significantly in both groups (p<0.05), but only the improvement in salbutamol use was greater in the high-dose group (p<0.05). During the run-out, the improvements in FEV1 and PC20 were rapidly reversed in both groups, but the improvements in peak flow and tryptase activity persisted; the improvement in sputum eosinophil concentration persisted only in the high-dose group (p<0.05). It was concluded that dose/response effects for FP are not easily demonstrable because low-dose FP is quite effective. For most outcomes, the effects of high- and low-dose FP are relatively short-lived after treatment is stopped. This finding raises questions about the extent to which inhaled corticosteroids are disease-modifying in asthma.

Airway inflammation and remodeling in asthma

An important advance in our understanding of the pathophysiology of asthma has been the discovery that airway inflammation is not confined to severe asthma but also characterizes mild and moderate asthma. Inflammation in asthma may be the result of a peculiar type of lymphocytic inflammation whereby Th2 lymphocytes secrete cytokines that orchestrate cellular inflammation and promote airway hyperresponsiveness. The term "airway remodeling" in asthma refers to structural changes that occur in conjunction with, or because of, chronic airway inflammation. Airway remodeling results in alterations in the airway epithelium, lamina propria, and submucosa, leading to thickening of the airway wall. The consequences of airway remodeling in asthma may include incompletely reversible airway narrowing, bronchial hyperresponsivenesss, airway edema, and mucus hypersecretion. Airway remodeling in asthma thus may predispose persons with asthma to asthma exacerbations and even death from airway obstruction caused by smooth muscle contraction, airway edema, and mucus plugging. Although much has been learned in the past 25 years about the pathophysiology of airway inflammation and airway remodeling in asthma, important questions remain about the relation between airway inflammation and remodeling, the natural history of airway remodeling, and the effects of current asthma treatments on remodeled airways.

Allergen-induced IL-9 directly stimulates mucin transcription in respiratory epithelial cells

A hallmark of asthma is mucin overproduction, a condition that contributes to airway obstruction. The events responsible for mucin overproduction are not known but are thought to be associated with mediators of chronic inflammation. Others have shown that T-helper 2 (Th2) lymphocytes are required for mucous cell metaplasia, which then leads to mucin overproduction in animal models of allergy. We hypothesized that Th2 cell mediators are present in asthmatic airway fluid and directly stimulate mucin synthesis in airway epithelial cells. Results in cultured airway epithelial cells showed that samples of asthmatic fluid stimulated mucin (MUC5AC) synthesis severalfold more potently than non-asthmatic fluid. Consistent with this, lavage fluid from the airways of allergen-challenged dogs stimulated mucin synthesis severalfold more potently than that from non-allergen-challenged dogs. Fractionation of dog samples revealed 2 active fractions at <10 kDa and 30-100 kDa. Th2 cytokines in these molecular weight ranges are IL-9 (36 kDa), IL-5 (56 kDa), and IL-13 (10 kDa). Antibody blockade of ligand-receptor interaction for IL-9 (but not IL-5 or IL-13) inhibited mucin stimulation by dog airway fluid. Furthermore, recombinant IL-9, but not IL-5 or IL-13, stimulated mucin synthesis. These results indicate that IL-9 may account for as much as 50-60% of the mucin-stimulating activity of lung fluids in allergic airway disease.

Effect of aerosolized anti-IgE (E25) on airway responses to inhaled allergen in asthmatic subjects

Intravenous administration of a humanized monoclonal antibody of IgE (E25) attenuates the early and late phase response to inhaled allergen in allergic asthmatic subjects. To test whether direct delivery of E25 to the airway might have the same effect, we conducted a randomized, double-blind, three group study in 33 subjects with mild allergic asthma (20 to 46 yr of age, 21 men, FEV(1) > 70% predicted). The airway responses to aerosolized allergen were determined at baseline, after 2 and 8 wk of once daily treatment with aerosolized placebo (n = 11), aerosolized E25 1 mg (n = 12), or aerosolized E25 10 mg (n = 10), and after 4 wk of treatment withdrawal. We found that E25 was detectable in the serum during aerosol treatment, although serum IgE did not change significantly in any of the three groups during treatment. In addition, both doses of E25 were no more effective than placebo in attenuating the early phase responses to allergen at both times during treatment. Although aerosolized E25 was generally well tolerated, one subject receiving aerosolized E25 10 mg daily was found to have serum IgG and IgA antibodies to E25. We conclude that aerosol administration of an anti-IgE monoclonal antibody does not inhibit the airway responses to inhaled allergen in allergic asthmatic subjects. We speculate that the observed lack of efficacy may be due to the inability of aerosol route of delivery to result in high enough concentrations of E25 in the tissue compartments surrounding IgE effector cells to neutralize IgE arising from local airway and pulmonary sources and IgE arising from the vascular space. Additionally, the aerosol route of delivery of monoclonal antibodies may be more immunogenic than the parenteral route.

Fractional analysis of sequential induced sputum samples during sputum induction: evidence that different lung compartments are sampled at different time points

BACKGROUND

The effect of the duration of sputum induction on markers of inflammation in induced sputum is unknown, and the optimal duration of sputum induction for research purposes in airway disease is uncertain.

OBJECTIVE

We sought to determine whether the duration of sputum induction influences the cellular or biochemical characteristics of induced sputum.

METHODS

Induced sputum was collected sequentially at 4-minute intervals during a 20-minute sputum induction in 12 subjects with mild and moderate asthma. Each 4-minute sample was collected and analyzed separately for total and differential cell counts and for levels of eosinophil cationic protein, fibrinogen, mucin-like glycoprotein, and surfactant protein SP-A.

RESULTS

The percentages of eosinophils and neutrophils were significantly higher at the beginning of the 20-minute sputum induction than at the end, whereas the percentage of macrophages was significantly lower at the beginning than at the end. In addition, the levels of eosinophil cationic protein and mucin-like glycoprotein were significantly higher at the beginning of the 20-minute induction than at the end, whereas the level of surfactant protein SP-A was significantly lower.

CONCLUSIONS

The duration of sputum induction significantly affects the cellular and biochemical composition of induced sputum in a manner suggesting that large airways are sampled at the beginning of sputum induction, whereas peripheral airways and alveoli are sampled at later time periods. Our data demonstrate the importance of standardizing the duration of sputum induction in clinical research studies, and on the basis of these data, we have chosen 12 minutes as the optimal duration for sputum induction in asthmatic subjects.

Neutrophil elastase and elastase-rich cystic fibrosis sputum degranulate human eosinophils in vitro

Neutrophils, eosinophils, and their proinflammatory constituents are important mediators of airway disease, and high levels of neutrophil proteases and eosinophil cationic protein (ECP) are found in sputum from patients with cystic fibrosis (CF). To investigate whether neutrophil proteases or CF sputum causes eosinophil degranulation, purified eosinophils from atopic asthmatic subjects were incubated for 2 h with neutrophil elastase, cathepsin G, and CF sputum, and the release of ECP was measured. We found that the percent release of ECP was higher after incubation with neutrophil elastase (10(-5) M) than with a buffer control [6.1 +/- 0.8 (SE) vs. 1.7 +/- 0.1%; P < 0.003] and represented >50% of the release caused by positive controls [Ca2+ ionophore A-23187 (5 x 10(-6) M) or serum-coated Sephadex beads]. The release of ECP after incubation with cathepsin G (2.3 +/- 0.2%) and CF sputum (6.2 +/- 2.0%) was also significantly higher than that with a buffer control (P < 0.05). Neutralization of free elastase activity with alpha1-proteinase inhibitor reduced the mean percent degranulation of eosinophils by neutrophil elastase by 50% (P = 0.0004) and by CF sputum by 75% (P = 0.02). Preincubation of eosinophils with cytochalasin B (10 mg/ml) and depletion of the incubation medium of Ca2+ also significantly attenuated degranulation of eosinophils incubated with purified free neutrophil elastase or CF sputum (P < 0.05). We conclude that neutrophil proteases, especially neutrophil elastase, and elastase-rich CF sputum cause degranulation of eosinophils in a mechanism partially dependent on Ca2+ and actin filaments.

Effect of low-dose beclomethasone dipropionate on asthma control and airway inflammation

The effects of usual or low doses of inhaled corticosteroids on airway mucosal inflammation have not yet been examined. We therefore, compared the effects of inhaled beclomethasone dipropionate (BDP) 336 microg x day(-1) on asthma control outcomes and markers of airway inflammation. Twenty-four adult subjects with mild and moderate asthma were randomized to receive either BDP or placebo for four weeks; then subjects entered a single blind four week placebo run-in period. We found that the BDP group had significantly greater improvements in forced expiratory volume in one second (FEV1), morning peak flow, and rescue salbutamol use than the placebo-treated group. The improvement in FEV1 largely reversed one week after treatment was stopped. The decrease in the median percentage of eosinophils in induced sputum in the BDP group from 3.8% to 3.4% was not significant, but because eosinophils increased from 8.4% to 12.7% in the placebo group, there was a significant difference between treatment groups (p=0.03). There was no significant difference between groups during treatment in the levels of eosinophil cationic protein (ECP), tryptase mucin-like glycoprotein, or fibrinogen in induced sputum. The change in FEV1 in the BDP group did not correlate significantly with the change in eosinophil percentage or ECP levels. We concluded that four weeks of treatment with inhaled beclomethasone dipropionate 336 microg x day(-1) was associated with significant improvements in peak flow, forced expiratory volume in one second, and rescue salbutamol use in asthmatic subjects but was not associated with large reductions in markers of eosinophilic inflammation, bronchovascular permeability, or mucus hypersecretion.

An evaluation of colchicine as an alternative to inhaled corticosteriods in moderate asthma. National Heart, Lung, and Blood Institute's Asthma Clinical Research Network

Colchicine demonstrates an array of anti-inflammatory properties of potential relevance to asthma. However, the efficacy of colchicine as an alternative to inhaled corticosteroid therapy for asthma is unknown. Five centers participated in a controlled trial testing the hypothesis that in patients with moderate asthma needing inhaled corticosteroids for control, colchicine provides therapeutic benefit as measured by maintenance of control when inhaled steroids are discontinued. Subjects were stabilized on triamcinolane acetonide (800 microg daily) and then enrolled in a 2-wk run-in during which all subjects took both colchicine (0.6 mg/twice a day) and triamcinolone. At the end of the run-in, all subjects discontinued triamcinolone and were randomized to continued colchicine (n = 35) or placebo (n = 36) for a 6-wk double-blind treatment period. The treatment groups were similar in terms of disease severity. After corticosteroid withdrawal, 60% of colchicine-treated and 56% of placebo-treated subjects were considered treatment failures as defined by preset criteria. No significant difference in survival curves was found between treatment groups (log rank = 0.38). Other measures, including changes in FEV1, peak expiratory flow, symptoms, rescue albuterol use, and quality of life scores, also did not differ between groups. Of note, subjects failing treatment had significantly greater methacholine responsiveness at baseline than did survivors (PC20, 0.81+/-1.38 versus 2.11+/-2.74 mg/ml; p = 0.01). An analysis of treatment failures suggested that the criteria selected for failure reflected a clinically meaningful but safe level of deterioration. We conclude that colchicine is no better than placebo as an alternative to inhaled corticosteroids in patients with moderate asthma. Additionally, we conclude that the use of treatment failure as the primary outcome variable in an asthma clinical trial where treatment is withdrawn is feasible and safe under carefully monitored conditions.

Safety of one method of sputum induction in asthmatic subjects

To assess the safety of sputum induction in asthmatic subjects, we conducted a retrospective review of data from 351 sputum inductions in 78 subjects from our institution. The sputum induction protcol consisted of baseline FEV1, pretreatment with albuterol 180 micrograms, postbronchodilator spirometry 15 min later, the induction procedure itself (inhalation of 3% saline for 20 min), and postsputum induction spirometry. We found that sputum induction was usually well tolerated, although some subjects developed wheeze and dyspnea. Overall, 11 of the 78 subjects (14%) had a fall in FEV1 of > or = 20% from the postbronchodilator baseline ("excessive bronchoconstriction") during their first sputum induction (range: -20 to -69%); no subject developed refractory bronchoconstriction requiring hospitalization or emergency room treatment. Only one of the 54 subjects (1.9%) with a baseline prebronchodilator FEV1 > 80% had excessive bronchoconstriction, whereas 10 of the 24 subjects (42%) whose baseline FEV1 was < or = 80% predicted did so. The change in FEV1 during sputum induction was significantly correlated with the baseline prebronchodilator FEV1% predicted, the baseline postbronchodilator FEV1% predicted, the PC20 for methacholine, and the percentage of eosinophils in induced sputum. We conclude that 180 micrograms albuterol does not prevent excessive bronchoconstriction in all asthmatic subjects undergoing sputum induction, especially in asthmatic subjects with a low baseline FEV1. Pulmonary function should be monitored regularly during sputum induction in asthmatic subjects to monitor for excessive bronchoconstriction.

The effect of an anti-IgE monoclonal antibody on the early- and late-phase responses to allergen inhalation in asthmatic subjects

A humanized murine monoclonal antibody directed to the Fc epsilonR1-binding domain of human IgE (rhuMAb-E25) has been shown to inhibit the binding of IgE to mast cells without provoking mast cell activation. To examine the effects of neutralizing IgE on allergic airway responses, we assessed the effects of 9 wk of treatment with rhuMAb-E25 in a parallel group, randomized, double-blind, placebo-controlled study of 19 allergic asthmatic subjects. We found that treatment with rhuMAb-E25 reduced serum IgE, increased the dose of allergen needed to provoke an early asthmatic response, reduced the mean maximal fall in FEV1 during the early response (30 +/- 10% at baseline to 18.8 +/- 8%, versus 33 +/- 8% at baseline to 34 +/- 4% after placebo; p = 0.01), and reduced the mean maximal fall in FEV1 during the late response (24 +/- 20% at baseline to 9 +/- 10% versus 20 +/- 17% at baseline to 18 +/- 17% after placebo; p = 0.047). We conclude that an anti-IgE monoclonal antibody, which inhibits binding of IgE to its receptor, suppresses the early- and late-phase responses to inhaled allergen in allergic asthmatic subjects. Targeting IgE with rhuMAb-E25 might be a useful treatment for allergic asthma.

Similar RANTES levels in healthy and asthmatic airways by immunoassay and in situ hybridization

To determine if RANTES expression is unregulated in the airways of asthmatic subjects, we performed bronchial mucosal biopsies and airway lavage in seven atopic asthmatic subjects and eight healthy subjects. Immunohistochemistry was used to reveal RANTES protein expression in the airway biopsies. An ELISA was used to quantitate RANTES in lavage. In three subjects in each group, we also used in situ hybridization to reveal mRNA for RANTES in airway biopsies. We found that the mean (+/- SD) percent expression for RANTES in the epithelium and submucosa was 26 +/- 9% and 26 +/- 10% in the asthmatic and healthy tissue samples, respectively. RANTES mRNA was demonstrable in the bronchial mucosa of both healthy and asthmatic subjects, predominantly in the epithelial cells but also in the submucosa. We also found that there was no significant difference in the median RANTES concentrations between the groups (healthy: 2.9 pg/ml [range: 0.0 to 28.7 pg/ml]; asthma: 1.8 pg/ml [range: 0.0 to 82.1 pg/ml], p > 0.05) despite a trend for higher concentrations of eosinophil cationic protein (ECP) in the asthmatic group (p = 0.08). In summary, this study confirms that cells in airway mucosal tissue produce RANTES but that the level of production in mild stable asthma is not different from that of healthy control subjects.

Comparison of two methods of collecting induced sputum in asthmatic subjects

The method that we have previously reported for sputum induction involves collecting the entire expectorate produced over a 20 min inhalation of 3% saline aerosol. This method presents the potential disadvantage of a considerable and variable salivary contribution to the induced sputum sample. In this study, we examined whether separate collection of saliva and sputum represents a better method for collecting induced sputum during sputum induction. In 11 stable asthmatics, we compared the volume, total and differential cell counts, and eosinophil cationic protein (ECP) levels in four induced sputum samples, two performed using our previous method (Method A) and two using another method (Method B) in which subjects spit saliva into one container before coughing sputum into another. We found that the volume of sputum obtained with Method B was lower than that obtained with Method A (6.16 +/- 0.61 vs 20.1 +/- 2.7 mL; p = 0.003), as was the percentage of squamous cells (34 +/- 4 vs 47 +/- 6; p = 0.023). In addition, the ECP levels in samples collected by Method B were higher (261 +/- 42 vs 145 +/- 26 ng.mL-1; p = 0.01). The differential counts of nonsquamous cells were similar except for the percentage of neutrophils, which was lower in Method B (37 +/- 4 vs 50 +/- 5%; p = 0.019). The repeatability of measurements of eosinophil percentages and of ECP levels was similar for the two methods. We conclude that separate collection of saliva and sputum yields induced sputum samples with reduced amounts of saliva and is, therefore, a better method for collecting induced sputum.

Comparison of regularly scheduled with as-needed use of albuterol in mild asthma. Asthma Clinical Research Network

BACKGROUND

Inhaled beta-agonists are the most commonly used treatment for asthma, but data suggest that regularly scheduled use of these agents may have deleterious effect on the control of asthma. We compared the effects of regularly scheduled use of inhaled albuterol with those of albuterol used only as needed in patients with mild chronic, stable asthma.

METHODS

In a multicenter, double-blind study, we randomly assigned 255 patients with mild asthma to inhale albuterol either on a regular schedule (126 patients) or only as needed (129 patients). The patients were followed for 16 weeks.

RESULTS

The primary outcome indicator, peak expiratory air flow measured in the morning, did not change significantly during the treatment period in the scheduled (416 liters per minute after the run-in period and 414 liters per minute after the treatment period) or the as-needed (424 liters per minute at both times) treatment groups (P=0.71). There were no significant differences between the two groups in peak flow variability, forced expiratory volume in one second, the number of puffs of supplemental albuterol needed, asthma symptoms, asthma quality-of-life score, or airway responsiveness to methacholine. The statistically significant differences between the groups in evening peak flow and in the short-term bronchodilator response to inhaled albuterol were small and judged to be clinically unimportant.

CONCLUSIONS

In patients with mild asthma, neither deleterious nor beneficial effects derived from the regular use of inhaled albuterol beyond those derived from use of the drug as needed. Inhaled albuterol should be prescribed for patients with mild asthma on an as-needed basis.

High-resolution computed tomography of airway changes after induced bronchoconstriction and bronchodilation in asthmatic volunteers

RATIONALE AND OBJECTIVES

We examined whether high-resolution computed tomography (HRCT) would detect and quantify induced airway changes in asthmatic volunteers.

METHODS

We performed pulmonary function tests and HRCT on eight asthmatic adults and two nonasthmatic control adults under three conditions: baseline, after methacholine inhalation, and after albuterol inhalation. Changes in pulmonary function, airway internal luminal diameter (AILD), and airway wall thickness (AWT) in the three conditions were compared.

RESULTS

After methacholine inhalation, pulmonary function showed significant airflow obstruction in the asthmatic volunteers compared with two nonasthmatic control volunteers. The median value for AILD decreased by 17% (p = .04). After subsequent inhalation of albuterol, pulmonary function improved to above the baseline levels in the eight asthmatic volunteers. The median value for AILD increased by 18% above the baseline value (p = .001). No changes in pulmonary function or AILD were seen in the two nonasthmatic volunteers. AWT did not change significantly in either the asthmatic or nonasthmatic volunteers after inhalation of methacholine or albuterol.

CONCLUSION

HRCT can quantify changes in the internal luminal diameter of asthmatic airways provoked by methacholine and albuterol inhalation.

Controversies involving inhaled beta-agonists and inhaled corticosteroids in the treatment of asthma

Controversy over the use of inhaled beta-agonists has dated almost from their introduction as a treatment for asthma. Their effectiveness as bronchodilators is not disputed, but there is concern that they may worsen asthma control if used regularly and that excessive use may increase the risk of death from asthma. Five years after the report from Sears and colleagues suggested that regular use of fenoterol worsens asthma control, we do not have definitive corroborative evidence that this effect of fenoterol is real or is shared by other members of the beta-agonist class. It also remains disputed whether the documented association between excessive beta-agonist use and death from asthma is a causal or a spurious association. Undisputed is the fact that excessive beta-agonist use by asthmatics indicates an increased risk of death from asthma and so indicates a need for clinicians to advise anti-inflammatory medications for these patients. Happily, although there are legitimate concerns about the possible implications of the development of tolerance to the non-bronchodilating effects of beta-agonists, there is currently little evidence that treatment with conventional doses of the beta-agonists currently available in the United States, including salmeterol, is harmful to asthmatic patients. The controversies over the use of inhaled corticosteroids revolve around the issue of whether the clinical benefit easily demonstrated with their short-term use is justified in the face of their possible long-term systemic toxicity. Unsettled questions about their therapeutic use include whether dose dependence can be shown for the clinical benefits of inhaled corticosteroids, whether delay in initiating inhaled corticosteroid treatment reduces the benefit that can be achieved, and whether the benefits of even prolonged therapy are short-lasting. The great unsettled question about their toxicity is whether systemic absorption of inhaled corticosteroids increases the risk of long-term systemic complications, like osteoporosis, cataracts, and growth inhibition. Current evidence suggests that significant risk of such toxicity is not likely to be associated with the long-term use of the equivalent of 800 micrograms/d of beclomethasone in adults and 400 micrograms/d in children. If higher doses are used to obtain greater clinical benefit, the answers to these questions may determine the place of new inhaled corticosteroids with high local potency and little systemic activity.

Effect of an NK1 receptor antagonist (CP-99,994) on hypertonic saline-induced bronchoconstriction and cough in male asthmatic subjects

To investigate the role of NK1 receptors in the pathogenesis of bronchoconstriction and cough in asthma, we performed a randomized, double-blind, crossover study on the effects of a selective non-peptide tachykinin NK1 receptor antagonist (CP-99,994) on baseline measures of lung function and on hypertonic saline-induced bronchoconstriction and cough in 14 male subjects with mild asthma. CP-99,994 (250 micrograms/2 hours) and placebo were administered intravenously in 2-h infusions during consecutive visits 5 to 7 d apart. Specific airway resistance (SRaw) was measured and spirometry was performed at baseline and at 35 and 60 min. Next, hypertonic saline challenge was performed by delivering 10 breaths of saline of increasing concentration (0.9 to 7% in 1% increments at 5-min intervals) via an ultrasonic nebulizer until SRaw increased from baseline by 200% or 20 units, whichever was greater. Throughout the challenge cough was counted from a taped record made from two microphones placed close to the subject's larynx. We found that CP-99,994 did not significantly affect SRaw or spirometric measures of lung function during the first hour of infusion. Although CP-99,994 infusion markedly attenuated the bronchoconstrictor response to the saline challenge in two subjects, it did not significantly decrease the area under curves obtained for SRaw and cough during saline challenge for the group as a whole (p = 0.9 for SRaw;p = 0.8 for cough). We conclude that administration of 250 micrograms/kg of CP-99,994 over 2 h does not significantly inhibit hypertonic saline-induced bronchoconstriction or cough in subjects with mild asthma and does not have acute bronchodilator activity in these subjects.