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 ß2 -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 ß2 -adrenergic agonists confer protection against pathologic airway changes is warranted.

A protective role for periostin and TGF-ß 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-ß. 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-ß1 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-ß 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-ß-induced T regulatory cell differentiation.

Structural changes to airway smooth muscle in cystic fibrosis.

BACKGROUND: Chronic airway obstruction is characteristic of cystic fibrosis (CF) but there are few studies of airway smooth muscle remodelling in CF. METHODS: Airway smooth muscle content and mean airway smooth muscle cell size were measured by applying design-based stereology to bronchoscopic biopsy specimens obtained from seven subjects with CF and 15 healthy controls. RESULTS: The smooth muscle content increased by 63% in subjects with CF (mean (SD) 0.173 (0.08) v 0.106 (0.042) mm(3) smooth muscle/mm(3) submucosa, mean difference -0.067; 95% CI -0.12 to -0.013, p = 0.017) but there was no increase in mean cell size (2705 (351) v 2654 (757) microm(3), mean difference -51; 95% CI -687 to 585, p = 0.87). CONCLUSIONS: These findings indicate hyperplasia of airway smooth muscle cells without hypertrophy and suggest that accumulation of airway smooth muscle cells may contribute to airway narrowing and bronchial hyperresponsiveness in CF.

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.

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.

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.

Differences between men and women in reporting of symptoms during an asthma exacerbation.

STUDY OBJECTIVE: Compared with men, women presenting to the emergency department with acute asthma are more likely to be admitted and to have a longer hospital stay. This study compares peak expiratory flow rate (PEFR) with reported symptom severity between men and women with acute asthma. The null hypothesis was that men and women report similar severity symptoms for similar levels of airway obstruction. METHODS: This study combined data from 4 prospective cohort studies performed from 1996 to 1998 as part of the Multicenter Airway Research Collaboration. Using a standardized protocol, investigators at 64 EDs in 21 US states and 4 Canadian provinces provided 24-hour per day coverage for a median of 2 weeks. RESULTS: Of the 1,291 patients with moderate to severe exacerbations (initial percentage of predicted PEFR <80%), 62% were women. Women were more likely than men to report "severe" complaints in terms of symptom frequency, symptom intensity, and resulting activity limitations (all P <.05). Women with moderate exacerbations were especially likely to describe their exacerbation as causing "severe" activity limitations (sex-PEFR interaction, P =.05). CONCLUSION: Men are less likely than women to report severe asthma symptoms and activity limitations in the presence of airway obstruction. This finding supports use of objective measures of airway obstruction when managing patients with asthma so that those whose symptoms do not reflect the severity of their obstruction can be recognized and properly treated. It also reconfirms the need for increased research on differences between men and women in acute asthma.

Relation between phase of menstrual cycle and emergency department visits for acute asthma.

Hormonal fluctuations during the menstrual cycle are hypothesized to influence the course of asthma among women. A recent study found that almost 50% of emergency department (ED) visits occur during the perimenstrual phase. Our prospective cohort study in 64 EDs examined the relation between phase of menstrual cycle and visits for acute asthma. A total of 288 women with acute asthma were evaluated with a standardized patient interview and medical record review after excluding subjects who were pregnant, on hormonal therapy, postmenopausal, status post hysterectomy, had incomplete reproductive data, or whose ED visit fell more than 28 d after their last menstrual period. Only 13% reported reproductive factors as a personal asthma trigger. For all subjects, ED asthma visits were classified by menstrual phase: 33% were preovulatory (Days 5 to 11), 26% were periovulatory (Days 12 to 18), 20% were postovulatory (Days 19 to 25), and 21% were perimenstrual (Days 26 to 4), p = 0.008. There was no significant association between phase of menstrual cycle and asthma severity. Our data indicate that ED visits for acute asthma among women are more frequent during the preovulatory phase in contrast to other studies reporting more visits in the perimenstrual phase.

Sudden-onset asthma exacerbations: clinical features, response to therapy, and 2-week follow-up. Multicenter Airway Research Collaboration (MARC) investigators.

Sudden-onset asthma exacerbations may have different triggers and responses to treatment than slower-onset exacerbations. The authors studied this hypothesis among patients with severe asthma exacerbations. The Multicenter Airway Research Collaboration prospectively enrolled patients presenting to 64 North American emergency departments with asthma exacerbations. Of 1,847 patients aged 18-54 yrs, 900 had severe exacerbations (peak expiratory flow rate (PEFR) <50% predicted or hospitalized without PEFR). These patients were divided into sudden-onset (< or =3 h of symptoms) and slower-onset (>3 h of symptoms) groups. Fourteen per cent (95% confidence interval, 11-16%) of patients with severe asthma exacerbations had sudden-onset exacerbations. Sudden-onset patients were similar to slower-onset patients, except triggers of their exacerbations were more often respiratory allergens, exercise or psychosocial stress and less often respiratory infections. Sudden-onset patients were more likely to have used oral beta-agonists and salmeterol in the preceding 4 weeks. Although initial PEFRs and management were similar, sudden-onset patients had a greater improvement in PEFR (35 versus 28% p<0.001). Sudden-onset patients were less often discharged on systemic corticosteroids, but had similar 2-week relapse rates compared with slower-onset patients. Among patients presenting with severe asthma exacerbations, sudden-onset exacerbations had a different pattern of triggers and greater improvement with treatment than slower-onset exacerbations.

Elevated plasma eotaxin levels in patients with acute asthma.

BACKGROUND: The eosinophil chemotactic and activating effects of eotaxin and the known association of eosinophils with asthma suggest that eotaxin expression is increased during asthma exacerbations. OBJECTIVE: We sought to determine whether plasma eotaxin levels are elevated in patients presenting for emergency treatment of acute asthma and to correlate eotaxin levels with disease activity and responses to treatment. METHODS: A case-control study of plasma eotaxin levels was performed in the 46 patients who presented for emergency asthma treatment and 133 age-, sex-, and ethnicity-matched subjects with stable asthma. RESULTS: Plasma eotaxin levels were significantly higher in 46 patients with acute asthma symptoms and airflow obstruction (520 pg/mL [250, 1100 pg/mL]; geometric mean [-1 SD, +1 SD]) than in 133 subjects with stable asthma (350 pg/mL [190, 620 pg/mL]; P =.0008). Among the patients with emergency asthma flares, those who responded to asthma treatment with an increase in peak expiratory flow rate by an amount equal to at least 20% of their predicted normal value had lower eotaxin levels than those who did not (410 pg/mL [210, 800 pg/mL] and 660 pg/mL [300, 1480 pg/mL], respectively; P =.04). CONCLUSION: These findings imply that eotaxin either is mechanistically involved in acute asthma or serves as a biomarker for activity of the CCR3 receptor ligand system, which is functionally linked to asthma.

Acute asthma among pregnant women presenting to the emergency department.

Asthma complicates up to 4% of pregnancies. Our objective was to compare emergency department (ED) visits for acute asthma among pregnant versus nonpregnant women. We performed a prospective cohort study, as part of the Multicenter Asthma Research Collaboration. ED patients who presented with acute asthma underwent a structured interview in the ED, and another by telephone 2 wk later. The study was performed at 36 EDs in 18 states. A total of 51 pregnant women and 500 nonpregnant women, age 18 to 39, were available for analysis. Pregnant women did not differ from nonpregnant women by duration of asthma symptoms (median: 0.75 versus 0.75 d, p = 0.57) or initial peak expiratory flow rate (PEFR) (51% versus 53% of predicted, p = 0.52). Despite this similarity, only 44% of pregnant women were treated with corticosteroids in the ED compared with 66% of nonpregnant women (p = 0.002). Pregnant women were equally likely to be admitted (24% versus 21%, p = 0.61) but less likely to be prescribed corticosteroids if sent home (38% versus 64%, p = 0.002). At 2-wk follow-up, pregnant women were 2.9 times more likely to report an ongoing exacerbation (95% CI, 1.2 to 6.8). Among women presenting to the ED with acute asthma, pregnant asthmatics are less likely to receive appropriate treatment with corticosteroids.

Effect of an emergency department asthma program on acute asthma care.

STUDY OBJECTIVE: To examine the effect of an emergency department program on acute asthma care. METHODS: We conducted a before-after study of an acute asthma quality improvement initiative in an urban teaching hospital with 65,000 annual ED visits. In mid-1994, a multidisciplinary group identified deficiencies in acute asthma care, developed and implemented a local version of the National Asthma Education Program's practice guidelines (including a standard asthma order sheet), and provided new peak flow (PF) meters. The "before" group comprised all adults with acute asthma seen during January 1994 (n=51); "after" groups comprised all adults with acute asthma seen during October 1994, February 1995, and June 1995 (n=145). Data were compared across months using a nonparametric test for trend. RESULTS: Although patient demographic characteristics and asthma severity were similar across months, ED process of care significantly changed. Initial PF measurements were obtained in 20% of patients before intervention, compared with 82%, 84%, and 83% during the postintervention months ( P for trend <.001). Follow-up PF readings were obtained in 22%, 70%, 78%, and 62% ( P <.001). Median delays to beta-agonist and steroid therapy decreased by approximately 16 minutes ( P <.001) and 34 minutes ( P =.04), respectively. Outcomes improved, with median ED length of stay decreasing by 58 minutes ( P =.01), and fewer inpatient admissions ( P =.05); there was no significant change in 4-week relapse to our hospital. CONCLUSION: A guideline-based ED asthma program changed clinical practice and improved acute asthma care in a sustained fashion. The effect of this intervention on cost and other outcomes is uncertain.

Sex differences among adults presenting to the emergency department with acute asthma. Multicenter Asthma Research Collaboration Investigators.

BACKGROUND: Asthma is an increasing problem worldwide, particularly among women. Sex differences in acute asthma presentation, management, or outcome would have important medical and economic implications. OBJECTIVE: To compare emergency department (ED) visits for acute asthma among women vs men. METHODS: We performed a prospective cohort study as part of the Multicenter Asthma Research Collaboration. Patients in the ED, aged 18 to 54 years, who presented with acute asthma underwent a structured interview in the ED and another by telephone 2 weeks later. The study was performed at 36 EDs in 18 states. Pregnant women with asthma were excluded (n=53). RESULTS: Of 1228 patients, 64.3% were women. Women did not differ significantly from men by age or education level, but women were more likely to be insured, have a primary care provider, and use inhaled corticosteroids. Women had a higher mean+/-SD peak expiratory flow rate than men, both early (expressed as percent predicted) (53%+/-21% vs 41%+/-18%; P<.001) and late (77%+/-24% vs 65%+/-21%; P<.001) in the ED stay. Despite this, women were more likely to be admitted to a hospital (multivariate odds ratio, 2.2; 95% confidence interval; 1.3-4.0) than men. At 2-week follow-up, women had not experienced more relapse events (odds ratio, 1.1) but were 1.5 times more likely to report an ongoing exacerbation (95% confidence interval; 1.0-2.4). CONCLUSIONS: Of adults who presented to the ED with acute asthma, women were almost twice as common as men. Although men received less outpatient care and had worse pulmonary function, women were more likely to be admitted to the hospital and to report an ongoing exacerbation at follow-up. Further studies are needed to better understand the complex relationship between sex and acute asthma.

Prospective multicenter study of relapse following treatment for acute asthma among adults presenting to the emergency department. MARC investigators. Multicenter Asthma Research Collaboration.

STUDY OBJECTIVE: To identify factors associated with relapse following treatment for acute asthma among adults presenting to the emergency department (ED). DESIGN: Prospective inception cohort study performed during October 1996 to December 1996 and April 1997 to June 1997, as part of the Multicenter Asthma Research Collaboration. SETTING: Thirty-six EDs in 18 states. PATIENTS: ED patients, aged 18 to 54 years, with physician diagnosis of acute asthma. For the present analysis, we restricted the cohort to patients sent home from the ED (n = 971), then further excluded patients with comorbid respiratory conditions (n = 32). This left 939 eligible subjects to have follow-up data. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Two weeks after being sent home from the ED, patients were contacted by telephone. A relapse was defined as an urgent or unscheduled visit to any physician for worsening asthma symptoms during the 14-day follow-up period. Complete follow-up data were available for 641 patients, of whom 17% reported relapse (95% confidence interval, 14 to 20). There was no significant difference in peak expiratory flow rate (PEFR) between patients who suffered relapse and those who did not. In a multivariate logistic regression analysis (controlling for age, gender, race, and primary care provider status), patients who suffered relapse were more likely to have a history of numerous ED (odds ratio [OD] 1.3 per 5 visits) and urgent clinic visits (OR 1.4 per 5 visits) for asthma in the past year, use a home nebulizer (OR 2.2), report multiple triggers of their asthma (OR 1.1 per trigger), and report a longer duration of symptoms (OR 2.5 for 1 to 7 days). CONCLUSION: Among patients sent home from the ED following acute asthma therapy, 17% will have a relapse and PEFR does not predict who will develop this outcome. By contrast, several historical features were associated with increased risk. Further research should focus on ways to decrease the relapse rate among these high-risk patients. The clinician may wish to consider these historical factors when making ED decisions.

Inhaled corticosteroids for asthma: are ED visits a missed opportunity for prevention?

Inhaled corticosteroids are effective but underused. This study evaluated the outpatient management of emergency department (ED) patients presenting with acute asthma and the relation of inhaled corticosteroid use to the patient's primary care provider (PCP) status. ED patients were interviewed by the hospital's asthma education program staff about their asthma. Overall, 85% (101 of 119) of asthmatics reported having a PCP. Although patients with a PCP and patients without a PCP both were using inhaled beta-agonists (93% v 89%, respectively; P = .54), patients without a PCP were less likely to be using inhaled corticosteroids (49% v 11%, P = .003). Controlling for age, acute asthma severity, and asthma hospitalizations during the past year, PCP status remained a significant predictor of inhaled corticosteroid use (odds ratio = 5.6; 95% confidence interval 1.1 to 27). Even among ED patients with a PCP, inhaled corticosteroids appear to be underused. ED asthma visits present an opportunity to initiate preventive measures such as inhaled corticosteroid use.

Sudden-onset severe acute asthma: clinical features and response to therapy.

OBJECTIVES: To characterize patients with sudden onset of severe acute asthma (SAA) and to examine whether this presentation is associated with rapid recovery. METHODS: Retrospective cohort study of ED visits to a teaching hospital. Subjects were aged 18-64 years, with SAA (n = 225), defined as initial peak expiratory flow rate (PEFR) < or =40% of predicted. Visits for sudden-onset SAA (< or =3 hours of symptoms) were characterized and multivariate logistic regression was used to examine the association between sudden onset and rapid recovery. RESULTS: Patient visits for sudden-onset SAA had different triggers as compared with those for the slower-onset group (p = 0.006). The sudden-onset patients were less likely to report an upper-respiratory-tract infection (17% vs 40%) and more likely to have an unidentifiable trigger (40% vs 19%). In the multivariate logistic regression model, sudden onset was a strong independent predictor of rapid response [odds ratio (OR) 4.3, 95% confidence interval (CI) 1.6-11.6]. Sudden-onset visits were less likely to lead to admission (23% vs 43%, p = 0.03). CONCLUSIONS: These data suggest that different triggers may be involved in sudden-onset SAA and that sudden onset of symptoms is independently associated with rapid recovery. In their rapid deterioration and rapid response, these subjects share certain characteristics with "sudden asphyxic asthmatics" and may constitute a population suitable for further study of factors contributing to that condition. While these visits led to admission less frequently, prospective studies are necessary to provide information on duration of response and risk for relapse.