A dual CysLT1/2 antagonist attenuates allergen-induced airway responses in subjects with mild allergic asthma.

BACKGROUND: The cysteinyl leukotrienes (cysLTs) play a key role in the pathophysiology of asthma. In addition to functioning as potent bronchoconstrictors, cysLTs contribute to airway inflammation through eosinophil and neutrophil chemotaxis, plasma exudation, and mucus secretion. We tested the activity of the dual cysLT1/2 antagonist, ONO-6950, against allergen-induced airway responses. METHODS: Subjects with documented allergen-induced early (EAR) and late asthmatic response (LAR) were randomized in a three-way crossover study to receive ONO-6950 (200 mg) or montelukast (10 mg) or placebo q.d. on days 1-8 of the three treatment periods. Allergen was inhaled on day 7 two hours postdose, and forced expiratory volume in 1 s (FEV1 ) was measured for 7 h following challenge. Sputum eosinophils and airway hyperresponsiveness were measured before and after allergen challenge. The primary outcome was the effect of ONO-6950 vs placebo on the EAR and LAR. RESULTS: Twenty-five nonsmoking subjects with mild allergic asthma were enrolled and 20 subjects completed all three treatment periods per protocol. ONO-6950 was well tolerated. Compared to placebo, ONO-6950 significantly attenuated the maximum % fall in FEV1 and area under the %FEV1 /time curve during the EAR and LAR asthmatic responses (P < 0.05) and allergen-induced sputum eosinophils. There were no significant differences between ONO-6950 and montelukast. CONCLUSIONS: Attenuation of EAR, LAR, and airway inflammation is consistent with cysLT1 blockade. Whether dual cysLT1/2 antagonism offers additional benefit for treatment of asthma requires further study.

[Bronchial thermoplasty in the treatment of severe adult asthma]. / La thermoplastie bronchique dans le traitement de l'asthme sévère de l'adulte.

Bronchial thermoplasty is a recent endoscopic technique for the treatment of severe asthma. It is an innovative treatment whose clinical efficacy and safety are beginning to be better understood. Since this is a device-based treatment, the evaluation procedure of risks and benefits is different that for pharmaceutical products; safety aspects, regulatory requirements, study design and the assessment of the magnitude of effects may all be different. The mechanism of action and optimal patient selection need to be assessed further in rigorous clinical and scientific studies. This technique is in harmony with the development of personalised medicine in the 21st century. It should be developed further in response to the numerous challenges and needs not yet met in the management of severe asthma.

Integrated care pathways for airway diseases (AIRWAYS-ICPs).

The objective of Integrated Care Pathways for Airway Diseases (AIRWAYS-ICPs) is to launch a collaboration to develop multi-sectoral care pathways for chronic respiratory diseases in European countries and regions. AIRWAYS-ICPs has strategic relevance to the European Union Health Strategy and will add value to existing public health knowledge by: 1) proposing a common framework of care pathways for chronic respiratory diseases, which will facilitate comparability and trans-national initiatives; 2) informing cost-effective policy development, strengthening in particular those on smoking and environmental exposure; 3) aiding risk stratification in chronic disease patients, using a common strategy; 4) having a significant impact on the health of citizens in the short term (reduction of morbidity, improvement of education in children and of work in adults) and in the long-term (healthy ageing); 5) proposing a common simulation tool to assist physicians; and 6) ultimately reducing the healthcare burden (emergency visits, avoidable hospitalisations, disability and costs) while improving quality of life. In the longer term, the incidence of disease may be reduced by innovative prevention strategies. AIRWAYSICPs was initiated by Area 5 of the Action Plan B3 of the European Innovation Partnership on Active and Healthy Ageing. All stakeholders are involved (health and social care, patients, and policy makers).

OX40L blockade and allergen-induced airway responses in subjects with mild asthma.

BACKGROUND: The OX40/OX40L interaction contributes to an optimal T cell response following allergic stimuli and plays an important role in the maintenance and reactivation of memory T effector cells. OBJECTIVE: We tested whether treatment with an anti-OX40L monoclonal antibody (MAb) would inhibit allergen-induced responses in subjects with asthma. METHODS: Twenty-eight mild, atopic asthmatic subjects were recruited for a double-blind, randomized, placebo-controlled, parallel-group trial (ClinicalTrials.gov identifier NCT00983658) to compare blockade of OX40L using a humanized anti-OX40L MAb to placebo-administered intravenously in 4 doses over 3 months. Allergen inhalation challenges were carried out 56 and 113 days after the first dose of study drug. The primary outcome variable was the late-phase asthmatic response. Other outcomes included the early-phase asthmatic response, airway hyperresponsiveness, serum IgE levels, blood and sputum eosinophils, safety and tolerability. RESULTS: Treatment with anti-OX40L MAb did not attenuate the early- or late-phase asthmatic responses at days 56 or 113 compared with placebo. In the anti-OX40L MAb treatment group, total IgE was reduced 17% from pre-dosing levels, and sputum eosinophils decreased 75% by day 113 (both P = 0.04). There was no effect of anti-OX40L MAb on airway hyperresponsiveness or blood eosinophils. The frequency of AEs was similar in both groups. CONCLUSION AND CLINICAL RELEVANCE: Pharmacological activity of anti-OX40L MAb was observed by decreases in serum total IgE and airway eosinophils at 16 weeks post-dosing, but there was no effect on allergen-induced airway responses. It is possible that the treatment duration or dose of antibody was insufficient to impact the airway responses.

Monitoring sputum eosinophils in mucosal inflammation and remodelling: a pilot study.

Normalisation of eosinophil counts in sputum of asthmatic patients reduces eosinophilic exacerbations. However, the effect of this strategy on airway remodelling remains to be determined. We compared bronchial inflammation and collagen deposition after 2 yrs of treatment guided by either sputum eosinophils (sputum strategy, SS) or by clinical criteria (clinical strategy, CS). As a pilot study, 20 mild asthmatic patients were randomly assigned to CS or SS strategies. Bronchial biopsies were obtained when minimum treatment needed to maintain control was identified and this was continued for 2 yrs. Biopsies were immunostained for inflammatory cells, mucin 5A (MUC5A) and collagen. The mean dose of inhaled corticosteroids at the start and end of the study was similar in both SS and CS groups. Forced expiratory volume in 1 s increased in both groups at the study end. In SS, mucosal lymphocyte and eosinophil counts, but not neutrophils, were reduced at the end of the study. In CS, only activated eosinophil and neutrophil counts decreased. MUC5A staining decreased in SS but not CS. No change in collagen deposition underneath the basement membrane was observed in either strategy. Treatment strategies that normalise sputum eosinophils also reduce mucosal inflammatory cells and MUC5A expression, but do not change subepithelial collagen deposition in mild to moderate asthma.

Influence of smoking on airway inflammation and remodelling in asthma.

BACKGROUND: Although exposure to tobacco smoke has been associated with increased morbidity and mortality, cigarette smoking is still common in the asthmatic population. Induced sputum neutrophilia has been observed in asthmatic smokers, but the effects of regular smoking on their bronchial mucosa morphology remain to be defined. This study documents the inflammatory and remodelling features in bronchial biopsies of smoking compared with non-smoking asthmatics. METHODS: We analysed bronchial biopsies from 24 steroid-naïve young subjects with mild asthma: 12 non-smoking and 12 currently smoking subjects. In addition to airway morphology assessment, inflammation and remodelling were analysed by immunohistochemistry using antibodies against CD3, CD68, major basic protein, neutrophil elastase, and tryptase. Expression of the cytokines IL-4, IL-5, IL-8, IFN-gamma, transforming growth factor-beta, and TNF was determined by in situ hybridization. RESULTS: Compared with non-smoking asthmatic subjects, smoking asthmatics' bronchial mucosa showed squamous cell metaplasia, in addition to increased expression of subepithelial neutrophil elastase, IFN-gamma, and intraepithelial IL-8. CONCLUSIONS: Smoking status modifies morphological and inflammatory processes in young subjects with mild asthma. The changes may possibly affect asthma treatment responses and clinical outcomes.

Induced sputum markers of fibrosis and decline in pulmonary function in asbestosis and silicosis: a pilot study.

OBJECTIVE: To evaluate the usefulness of fibrogenic cytokines and mediators in the analysis of induced sputum and determine if their levels correlated with previous decline in lung function in asbestosis and silicosis. DESIGN: In a pilot study for the evaluation of 19 workers with asbestosis and 15 with silicosis, all workers had chart reviews and records of previous lung function tests. Fourteen healthy control subjects were also included in the study. All subjects attended the laboratory for a clinical evaluation, pulmonary function tests and induced sputum sampling. Differential cell counts were performed and the following mediators and cytokines were measured: matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinases 1 (TIMP-1), fibronectin, interleukin 1 beta (IL-1beta), IL-6, IL-8, IL-12, transforming growth factor beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha). RESULTS: Levels of IL-1beta were higher in the sputum of subjects with asbestosis and silicosis than in controls. Eosinophils, neutrophils and IL-1beta levels were significantly correlated with the rate of decline in pulmonary function. CONCLUSION: The induced sputum levels of certain inflammatory cells and IL-1beta correlate with the decline in pulmonary function associated with asbestosis and silicosis. It remains to be established if these markers can help predict the clinical outcome of workers exposed to these mineral particles or fibers in a prospective study.

Cigarette smoking and asthma: a dangerous mix.

In Canada, 20% to 30% of the general population currently smoke. Smoking is as common in those suffering from asthma as it is in the general population. However, most studies on the pathophysiology of asthma and its response to treatment only include nonsmokers. Available data that examine the influence of smoking on clinical, functional and inflammatory characteristics of asthma, as well as the influence of smoking on the therapeutic response to corticosteroids, were reviewed. Active smoking is associated with an increased morbidity from asthma and impairs the response to inhaled corticosteroids. These observations emphasize the need for smoking cessation in patients with asthma and for reassessment of current treatment guidelines in this population.

Variability of inflammatory cell counts on bronchial biopsies of normal subjects.

Bronchial biopsies are currently used to study the pathophysiology of airway diseases, and comparisons are often made with biopsies from healthy volunteers. It is therefore important to evaluate the variability in each parameter analyzed in bronchial biopsies of healthy volunteers in order to be able to discriminate significant changes. We analyzed bronchial biopsies of 31 nonsmoking, nonatopic healthy subjects who volunteered as normal controls for studies on pathophysiology of asthma. Mean % epithelial desquamation was 23.7% of observed total epithelial length. No subepithelial fibrosis was observed. Inflammatory cell counts (/mm(2) connective tissue surface) were variable among subjects but not different between small (

Airway inflammation in asthma with incomplete reversibility of airflow obstruction.

This study aimed to determine whether there is a persistent or different type of airway inflammation in patients with an incomplete reversibility of airflow obstruction (IRAO) despite optimal treatment and if so, whether it is associated with an accelerated decline of pulmonary function. Fifteen asthmatic patients with IRAO, and 23 with complete reversibility of airflow obstruction (CRAO) had a spirometry and an induced-sputum (IS) analysis. Past FEV1 values were recorded over 2-12 years during periods of stable asthma. Medians (range) for IS cell differentials were: lymphocytes, 0(0-3)/1(0-2)%; neutrophils, 56(13-88)/38(3-84)% and eosinophils, 2.0(0-82)/4.0(0-68)%, (all P>0.05). Among non-smoking patients, those with IRAO had more neutrophils in IS than those with CRAO (P=0.019). Mean (+/-SEM) yearly fall in FEV1 in IRAO or CRAO patients was 54+/-21/84+/-16 ml/year (P>0.05, predicted age-related decline < or = 26 ml/year, P=0.0008). In the whole group of asthmatic patients, decline of FEV1/year was inversely correlated with the % neutrophils in sputum (r(s)=-0.436, P=0.008) and, in IRAO patients, with the duration of asthma (r(s)=-0.559, P=0.037). In conclusion, persistent airway inflammation and increased decline in pulmonary function can be observed in both asthmatic patients with IRAO/CRAO and are of similar magnitude. Non-smoking patients with IRAO had more neutrophils in IS than CRAO.

TH2 cytokine-associated transcription factors in atopic and nonatopic asthma: evidence for differential signal transducer and activator of transcription 6 expression.

BACKGROUND: The expression of IL-4 and IL-5 is increased in patients with atopic asthma compared with control subjects and correlates with indices of pulmonary function. In nonatopic asthma the expression of IL-4, unlike IL-5, fails to correlate with pulmonary function, and compared with their atopic counterparts, these patients have fewer cells expressing IL-4 receptor (IL-4R). As such, a deficiency in the IL-4 signaling pathway may be implicated in nonatopic asthma. The transcription factors GATA-3 and cMAF mediate IL-4 and IL-5 synthesis, whereas signal transducer and activator of transcription 6 (STAT-6) is critical for IL-4R signaling. OBJECTIVE: This study examines the expression profile of these transcription factors in asthma, according to atopic status. METHODS: With immunocytochemistry, the expression of GATA-3, cMAF, and STAT-6 protein was determined in sections of bronchial biopsy specimens from patients with atopic asthma (n = 7), patients with nonatopic asthma (n = 8), and control subjects (n = 8). RESULTS: Higher numbers of cells expressing GATA-3 and cMAF were observed in patients with atopic and those with nonatopic asthma than in control subjects and patients with tuberculosis (P <.001). There were also more STAT-6-immunoreactive cells in patients with atopic and those with nonatopic asthma than in control subjects (P <.0001, P <.05). Notably, however, fewer cells expressing STAT-6 protein were observed in nonatopic versus atopic asthma (P <.0001). CONCLUSIONS: These results demonstrate the upregulation of GATA-3 and cMAF in both variants of asthma and indicate that reduced IL-4R signaling, because of lower STAT-6 expression, may be a feature of nonatopic asthma.

Bronchial mucosa produced by tissue engineering: a new tool to study cellular interactions in asthma.

BACKGROUND: The use of fiberoptic bronchial biopsies has improved our understanding of the immunopathology of asthma. However, this approach offers a limited ability to perform mechanistic studies observing cell-cell and cell-matrix interactions, which are a key issue in the study of airway remodeling. Tissue engineering is a technique that combines the use of biology and engineering expertise to generate a limitless amount of tissue from small samples. This technology allows for the study of cell interactions under conditions as close as possible to the natural environment. OBJECTIVE: The aim of this study was to evaluate the feasibility of an engineered human bronchial mucosa as a model to study cellular interactions in asthma. METHODS: Human bronchial fibroblasts from normal and asthmatic donors were incorporated into collagen gel. Bronchial epithelial cells were seeded over this gel and then cultured in an air-liquid interface in the presence or the absence of T lymphocytes. Biopsy specimens from these engineered mucosa were taken for structural and ultrastructural analysis, and T lymphocytes were harvested and used to localize IL-5. RESULTS: Histologic analysis showed that engineered mucosa with normal bronchial cells presented a pseudostratified ciliated epithelium with the presence of mucus secretory cells. The electron microscopy analysis confirmed these histologic results. These features were comparable with those observed in normal bronchial tissues. However, in engineered mucosa from asthmatic subjects, the tissue structure was disorganized, particularly the epithelial cell arrangement. The percentage of IL-5(+) lymphocytes was significantly (P =.03) higher in engineered bronchial mucosa from asthmatic subjects (87% +/- 2%) compared with mucosa from normal volunteers (2% +/- 0.3%). CONCLUSION: Using tissue engineering, we produced an in vitro model of bronchial mucosa from normal and asthmatic subjects. These models could be a valuable tool to better understand key mechanisms involved in inflammation and airway repair.

Cytokine expression in the lower airways of nonasthmatic subjects with allergic rhinitis: influence of natural allergen exposure.

BACKGROUND: Natural exposure to pollen provokes an increase in airway responsiveness in nonasthmatic subjects with seasonal allergic rhinitis. This natural exposure may induce inflammatory cell recruitment and cytokine release, leading to lower airway inflammation. OBJECTIVE: The aim of this study was to characterize lower airway inflammation in nonasthmatic pollen-sensitive subjects. METHODS: We performed immunohistochemical tests on bronchial biopsy specimens from subjects with rhinitis who had no past or current history of asthma to evaluate cytokine expression and inflammatory cell numbers and activation both in and out of the pollen season. RESULTS: The number of CD4(+), CD8(+), and CD45RO(+) lymphocyte subpopulations were significantly higher during the pollen season compared with the out-of-season period (P <.04). Furthermore, EG1(+) cells tended to increase after natural pollen exposure (P =.06). The number of IL-5(+) cells increased significantly after natural exposure to pollen compared with out-of-season numbers (P <.01). This increase in IL-5 expression was correlated with the numbers of CD3(+), CD4(+), CD45RO(+), and EG1(+) cells. The numbers of tryptase-positive, IFN-gamma(+), and IL-4(+) cells did not change after natural exposure. CONCLUSION: This study showed that natural pollen exposure was associated with an increase in lymphocyte numbers, eosinophil recruitment, and IL-5 expression in the bronchial mucosa of nonasthmatic subjects with allergic rhinitis.

Airway hyperresponsiveness, inflammation, and subepithelial collagen deposition in recently diagnosed versus long-standing mild asthma. Influence of inhaled corticosteroids.

This study aimed at documenting airway inflammation and subepithelial collagen deposition in patients using only inhaled beta(2)-agonists with either recently diagnosed asthma (RDA: /= 13 yr, n = 16) and at the influence of an intense inhaled corticosteroid (ICS) treatment on these parameters, in relation to changes in airway responsiveness. Patients had a methacholine inhalation test and a bronchoscopy with bronchial biopsies before and after an 8-wk treatment with inhaled fluticasone propionate (FP), 1,000 microgram/day. Baseline FEV(1) (mean +/- SEM) was normal and similar in both groups (RDA: 98.1 +/- 2.7, LSA: 94.5 +/- 4.6%). Geometric mean methacholine PC(20) was lower in LSA than in RDA (0.44 versus 3.37 mg/ml) at baseline and improved similarly by 1.85 and 1.86 double concentrations with FP treatment. PC(20) normalized (>/= 16 mg/ml) in five patients with RDA and two patients with LSA. Baseline mean bronchial cell counts (per mm(2) connective tissue surface) for CD3(+), CD4(+), CD8(+), CD25(+), EG1(+), CD45ro(+), and AA1(+) cells were similar in both groups. With FP, EG1(+) (p < 0.001), EG2(+) (p = 0.018), and AA1(+) counts (p = 0.009) decreased significantly in both groups while CD45ro(+) (p = 0.02) counts decreased only in LSA. Baseline type 1 and type 3 collagen deposition underneath the basement membrane was similar in RDA and LSA and did not change significantly after FP. This study shows that recent compared to long-standing mild asthma is associated with a similar degree of airway inflammation and subepithelial fibrosis, and a similar improvement in airway hyperresponsiveness after 8 wk on high-dose ICS. It also indicates that once asthma becomes symptomatic, airway responsiveness cannot normalize in most subjects over such a time period, even with a high dose of ICS.

Eosinophil activation status and corticosteroid responsiveness in severe asthma.

BACKGROUND: Since eosinophils are implicated in asthma pathogenesis, we investigated whether these cells were activated in severe asthma. METHODS: Twenty-six asthmatics with different clinical responses to oral corticosteroid (CS), i.e. sensitive [change in forced expiratory volume in 1 s (DeltaFEV(1)) >/= 25% after oral methylprednisolone, 40 mg daily, for 14 days, n = 7], resistant (DeltaFEV(1) /= 20 mg oral prednisone daily for acceptable asthma control, n = 10), were studied. RESULTS: Calcium ionophore-induced leukotriene (LT) C(4) release of purified blood eosinophils was similar in the three groups. Cell incubation with granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced ionophore-induced LTC(4) release, and this effect was higher in CS-sensitive (5-fold) than in CS-resistant subjects (1.7-fold) (p = 0.02). CS treatment decreased blood eosinophil counts in these two groups of subjects (p

Asthma and airway hyper-responsiveness in adults who required hospital admission for bronchiolitis in early childhood.

Viral respiratory infections in infancy may contribute to the development of airway hyper-responsiveness (AHR) in childhood but their effects on respiratory function at the adult age are still uncertain. A group of 42 subjects aged 17-35 with a pediatrician-made diagnosis of severe bronchiolitis in infancy (Br) were compared for the presence of asthma and AHR to a control group (C) paired for age and gender, without evidence of lower respiratory disease in infancy. All had a respiratory and environmental questionnaire, allergy skin prick tests, blood eosinophil count, total serum IgE determination and measurements of expiratory flows and airway response to methacholine. In Br and C groups, respectively, 38 and 12% of subjects had a physician-made diagnosis of asthma, 26 and 7% used bronchodilators and 12 and 0% an inhaled corticosteroid; 71 and 67%, respectively, were atopic, 50 and 24% were smokers and 43 and 17% had a first-degree relative with asthma. Mean baseline FEV1 and FEV1/FVC ratio were lower in the Br than in the C group, with 94/103% (P=0.002) and 80/87 (P<0.0001) of the predicted value, respectively. Geometric mean PC20 methacholine was significantly lower in the Br than in the C group 3.9/20.3 mg ml(-1) (P<0.0001). Mean blood eosinophil count and serum IgE levels were similar in both groups (P> 0.05). In conclusion, asthma and AHR were found more frequently in young adults with a past history of bronchiolitis, suggesting that this type of respiratory infection may contribute to altered pulmonary function in adulthood, although it may also represent an early manifestation of asthma. The influence of potential confounding factors, such as familial predisposition and exposure to cigarette smoke on the development of asthma and AHR in the Br group, cannot be excluded.

Synergistic action of endothelin (ET)-1 on the activation of bronchial fibroblast isolated from normal and asthmatic subjects.

Bronchial subepithelial fibrosis is an histological characteristic of asthma. Cytokines and other mediators, such as PDGF-BB, TGF-beta1 and ET-1 found in the asthmatic submucosa can potentially activate a repair process that leads to fibroblast proliferation and collagen synthesis. The mechanisms of modulation of the repair process leading to extracellular matrix deposition are still to be documented. In this study, we assessed the in vitro proliferation and collagen synthesis of bronchial fibroblasts isolated from normal and asthmatic subjects in response to ET-1, platelet-derived growth factor (PDGF)-BB and transforming growth factor (TGF)-beta1 alone or in combination, in the presence or absence of dexamethasone. The combination of ET-1 with one of the other two growth factors, or the triple combination, significantly increased DNA synthesis and collagen production of bronchial fibroblasts isolated from both normal and asthmatic subjects, but the same growth factors used separately had no significant effect on the same parameters. These results suggest that the simultaneous presence of ET-1, PDGF-BB and TGF-beta1 in both normal and asthmatic subjects is necessary to activate bronchial fibroblast proliferation and collagen synthesis. As these mediators are present in the submucosa of the asthmatic bronchi, they could be responsible, at least in part, for the accumulation of collagen in the mucosa.

Montelukast reduces airway eosinophilic inflammation in asthma: a randomized, controlled trial.

Leukotrienes are pro-inflammatory mediators which may contribute to tissue, sputum, and blood eosinophilia seen in allergic and inflammatory diseases, including asthma. Montelukast is a cysteinyl leukotriene1 (CysLT1) receptor antagonist which improves asthma control; the aim of this study was to investigate its effect on induced sputum eosinophils. Montelukast 10 mg (n=19) or placebo (n=21) were administered orally once in the evening for 4 weeks to 40 chronic adult asthmatic patients, aged 19-64 yrs, in a double-blind, randomized, parallel group study. Patients were included if, at prestudy, they had >5% sputum eosinophils, symptomatic asthma with a forced expiratory volume in one second > or =65% of the predicted value and were being treated only with "as needed" inhaled beta2-agonists. In addition to sputum eosinophils, blood eosinophils and clinical endpoints were also assessed. Four weeks of montelukast treatment decreased sputum eosinophils from 7.5% to 3.9% (3.6% decrease, 95% confidence interval (CI) -16.6-0.4). In contrast, placebo treatment was associated with an increase in sputum eosinophils from 14.5% to 17.9% (3.4% increase, 95% CI -3.5-9.8). The least squares mean difference between groups (-11.3%, 95% CI -21.1-(-1.4)) was significant (p=0.026). Compared with placebo, montelukast significantly reduced blood eosinophils (p=0.009), asthma symptoms (p=0.001) and beta2-agonist use (p<0.001) while significantly increasing morning peak expiratory flow (p=0.001). Montelukast was generally well tolerated in this study, with a safety profile similar to the placebo. These results demonstrate that montelukast decreases airway eosinophilic inflammation in addition to improving clinical parameters. Its efficacy in the treatment of chronic asthma may be due, in part, to the effect on airway inflammation.

Asymptomatic airway hyperresponsiveness: relationships with airway inflammation and remodelling.

To study the physiopathology and significance of asymptomatic airway hyperresponsiveness (AHR), the clinical and bronchial immunohistological parameters were evaluated in subjects with asymptomatic and symptomatic AHR. Asymptomatic subjects with AHR (eight females/two males, no respiratory symptoms, provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (PC20) <8 mg x mL(-1) and no treatment) were compared with asthmatic subjects paired for age, sex and PC20, and with nonatopic, nonasthmatic controls paired for age and sex. All three groups were evaluated once at baseline, whilst the asymptomatic AHR subjects were re-evaluated after 1 and 2 yrs. Measurements included spirometry, methacholine challenge, serum immunoglobulin (Ig)E, blood eosinophils, and bronchoscopy (at baseline and after 2 yrs only). At first evaluation, the mean blood eosinophil count, total serum IgE level, atopic index, baseline forced expiratory volume in one second (FEV1) and the degree of bronchial epithelial desquamation of the asymptomatic AHR subjects were similar to those of asthmatic subjects. However, they presented focal rather than the continuous bronchial subepithelial fibrosis observed in asthmatics. Their mucosal CD3, CD4, CD25, EG1 and EG2-positive cell counts were intermediate between those of the control subjects and asthmatics. At the end of the 2-yr follow-up, four of them had developed asthma symptoms. At this time, bronchial biopsies revealed an increase in the extent of subepithelial fibrosis and in the number of CD25 and CD4-positive cells, and a decrease in the number of CD8+ cells, particularly in subjects who developed asthma symptoms. These data suggest that asymptomatic airway hyperresponsiveness is associated with airway inflammation and remodelling, and that the appearance of asthma symptoms is associated with an increase in these features, particularly the CD4/CD8 ratio and airway fibrosis. Consequently, this study proposes an association between asymptomatic airway hyperresponsiveness and airway inflammation, structural changes and asthma although these relationships remain to be further evaluated.