Evidence of a role of tumor necrosis factor alpha in refractory asthma.

BACKGROUND: The development of tumor necrosis factor alpha (TNF-alpha) antagonists has made it feasible to investigate the role of this cytokine in refractory asthma. METHODS: We measured markers of TNF-alpha activity on peripheral-blood monocytes in 10 patients with refractory asthma, 10 patients with mild-to-moderate asthma, and 10 control subjects. We also investigated the effects of treatment with the soluble TNF-alpha receptor etanercept (25 mg twice weekly) in the patients with refractory asthma in a placebo-controlled, double-blind, crossover pilot study. RESULTS: As compared with patients with mild-to-moderate asthma and controls, patients with refractory asthma had increased expression of membrane-bound TNF-alpha, TNF-alpha receptor 1, and TNF-alpha-converting enzyme by peripheral-blood monocytes. In the clinical trial, as compared with placebo, 10 weeks of treatment with etanercept was associated with a significant increase in the concentration of methacholine required to provoke a 20 percent decrease in the forced expiratory volume in one second (FEV1) (mean difference in doubling concentration changes between etanercept and placebo, 3.5; 95 percent confidence interval, 0.07 to 7.0; P=0.05), an improvement in the asthma-related quality-of-life score (by 0.85 point; 95 percent confidence interval, 0.16 to 1.54 on a 7-point scale; P=0.02), and a 0.32-liter increase in post-bronchodilator FEV1 (95 percent confidence interval, 0.08 to 0.55; P=0.01). CONCLUSIONS: Patients with refractory asthma have evidence of up-regulation of the TNF-alpha axis. (ClinicalTrials.gov number, NCT00276029.).

Increased sputum and bronchial biopsy IL-13 expression in severe asthma.

BACKGROUND: The importance of IL-13 in the asthma paradigm is supported by increased expression in human subjects, particularly in patients with mild-to-moderate asthma. However, the role of IL-13 in severe asthma needs to be further defined. OBJECTIVE: We sought to assess IL-13 expression in sputum and bronchial biopsy specimens from subjects with mild-to-severe asthma. METHODS: Sputum IL-13 concentrations were measured in 32 control subjects, 34 subjects with mild asthma, 21 subjects with moderate asthma, and 26 subjects with severe asthma. Enumeration of mast cells, eosinophils, and IL-13+ cells in the bronchial submucosa and airway smooth muscle (ASM) bundle was performed in 7 control subjects, 14 subjects with mild asthma, 7 subjects with moderate asthma, and 7 subjects with severe asthma. RESULTS: The proportion of subjects with measurable IL-13 in the sputum was increased in the mild asthma group (15/34) and severe asthma group (10/26) compared with that seen in the control group (4/32; P = .004). IL-13+ cells were increased within the submucosa in all asthma severity groups compared with control subjects (P = .006). The number of IL-13+ cells were increased within the ASM bundle in the severe asthma group compared with that seen in the other groups (P < .05). Asthma control questionnaire scores positively correlated with sputum IL-13 concentrations (R(s) = 0.35, P = .04) and mast cells in the ASM bundle (R(s) = 0.7, P = .007). IL-13+ cells within the submucosa and ASM correlated with sputum eosinophilia (R(s) = 0.4, P < or = .05). CONCLUSIONS: IL-13 overexpression in sputum and bronchial biopsy specimens is a feature of severe asthma.

The use of exhaled nitric oxide to guide asthma management: a randomized controlled trial.

RATIONALE: Current asthma guidelines recommend adjusting antiinflammatory treatment on the basis of the results of lung function tests and symptom assessment, neither of which are closely associated with airway inflammation. OBJECTIVES: We tested the hypothesis that titrating corticosteroid dose using the concentration of exhaled nitric oxide in exhaled breath (Fe(NO)) results in fewer asthma exacerbations and more efficient use of corticosteroids, when compared with traditional management. METHODS: One hundred eighteen participants with a primary care diagnosis of asthma were randomized to a single-blind trial of corticosteroid therapy based on either Fe(NO) measurements (n = 58) or British Thoracic Society guidelines (n = 60). Participants were assessed monthly for 4 months and then every 2 months for a further 8 months. The primary outcome was the number of severe asthma exacerbations. Analyses were by intention to treat. MEASUREMENTS AND MAIN RESULTS: The estimated mean (SD) exacerbation frequency was 0.33 per patient per year (0.69) in the Fe(NO) group and 0.42 (0.79) in the control group (mean difference, -21%; 95% confidence interval [CI], -57 to 43%; p = 0.43). Overall the Fe(NO) group used 11% more inhaled corticosteroid (95% CI, -17 to 42%; p = 0.40), although the final daily dose of inhaled corticosteroid was lower in the Fe(NO) group (557 vs. 895 microg; mean difference, 338 microg; 95% CI, -640 to -37; p = 0.028). CONCLUSIONS: An asthma treatment strategy based on the measurement of exhaled nitric oxide did not result in a large reduction in asthma exacerbations or in the total amount of inhaled corticosteroid therapy used over 12 mo, when compared with current asthma guidelines. Clinical trial registered with www.controlled-trials.com (ISRCTN08067387).

IL-4-expressing bronchoalveolar T cells from asthmatic and healthy subjects preferentially express CCR 3 and CCR 4.

BACKGROUND: The concept of the polarization of chemokine receptor expression by T(H)1 and T(H)2 cells provides an attractive mechanism for their differential recruitment to tissue, which could be subject to disease-specific therapeutic intervention. The paradigm that T(H)1 cells preferentially express CXCR 3 and CCR 5 and T(H)2 cells preferentially express CCR 3, CCR 4, and CCR 8 has been well established in the setting of in vitro polarized cell lines; however, the situation in vivo appears less clear-cut. OBJECTIVE: We sought to investigate whether this pattern of polarization can be demonstrated in human lung tissue. METHODS: We used single-cell analysis to investigate the relationship between chemokine receptor expression and cytokine production on peripheral blood and bronchoalveolar lavage fluid T cells in patients with asthma, a putative T(H)2 disease, as well as in healthy control subjects. RESULTS: We have found in both asthmatic and control subjects that IL-4-expressing blood and bronchoalveolar lavage fluid T cells are significantly more likely to express the T(H)2 type 2 chemokine receptors CCR 3 and CCR 4, with 10-fold and 2-fold differences in expression, respectively, compared with IFN-gamma-expressing cells. CONCLUSION: We have provided evidence that polarization of T(H)2-type chemokine receptors on IL-4-expressing cells can be demonstrated in an in vivo setting and therefore that these cells might indeed be susceptible to differential patterns of recruitment as a result of expression of the relevant chemokines at inflammatory sites.

Sputum and bronchial submucosal IL-13 expression in asthma and eosinophilic bronchitis.

BACKGROUND: Nonasthmatic eosinophilic bronchitis is a condition characterized by the presence of eosinophilic airway inflammation in the absence of airflow obstruction or airway hyperresponsiveness. In asthma, the T H 2-type cytokine IL-13 has been implicated in the development of airway inflammation and hyperresponsiveness. Whether the expression of IL-13 is different between these 2 conditions is unknown. OBJECTIVE: We sought to investigate whether IL-13 expression is increased in asthma compared with eosinophilic bronchitis. METHODS: Sputum samples from subjects with mild asthma (n = 30) and eosinophilic bronchitis (n = 15) and normal controls (n = 16) were dialyzed, and IL-13 concentration was measured by ELISA. In a subgroup of these patients, IL-13 protein expression in bronchial biopsies was assessed by immunohistochemistry. RESULTS: The concentration of sputum IL-13 was higher in patients with mild asthma than in normal controls ( P = .03) and in patients with eosinophilic bronchitis ( P = .03). The median (interquartile range) number of IL-13 + cells/mm 2 submucosa was significantly higher in asthma 4 (8) than eosinophilic bronchitis 1.7 (1.9) and normal controls 0.5 (1.1; P = .004). Eighty-three percent of the cells expressing IL-13 in the submucosa were eosinophils, and 8% were mast cells. The median (interquartile range) proportion of eosinophils that expressed IL-13 was higher in the subjects with asthma, 16 (10)%, than those with eosinophilic bronchitis, 7 (3)% ( P = .02). CONCLUSION: The increased expression of IL-13 in asthma compared with eosinophilic bronchitis supports the concept that IL-13 may play a critical role in the pathophysiology of asthma.