Interleukin-11 receptor subunit α-1 is required for maximal airway responsiveness to methacholine after acute exposure to ozone

Interleukin (IL)-11, a multifunctional cytokine, contributes to numerous biological processes, including adipogenesis, hematopoiesis, and inflammation. Asthma, a respiratory disease, is notably characterized by reversible airway obstruction, persistent lung inflammation, and airway hyperresponsiveness (AHR). Nasal insufflation of IL-11 causes AHR in wild-type mice while lung inflammation induced by antigen sensitization and challenge, which mimics features of atopic asthma in humans, is attenuated in mice genetically deficient in IL-11 receptor subunit α-1 (IL-11Rα1-deficient mice), a transmembrane receptor that is required conjointly with glycoprotein 130 to transduce IL-11 signaling. Nevertheless, the contribution of IL-11Rα1 to characteristics of nonatopic asthma is unknown. Thus, based on the aforementioned observations, we hypothesized that genetic deficiency of IL-11Rα1 attenuates lung inflammation and increases airway responsiveness after acute inhalation exposure to ozone (O3), a criteria pollutant and nonatopic asthma stimulus. Accordingly, 4 and/or 24 h after cessation of exposure to filtered room air or O3, we assessed lung inflammation and airway responsiveness in wild-type and IL-11Rα1-deficient mice. With the exception of bronchoalveolar lavage macrophages and adiponectin, which were significantly increased and decreased, respectively, in O3-exposed IL-11Rα1-deficient as compared with O3-exposed wild-type mice, no other genotype-related differences in lung inflammation indices that we quantified were observed in O3-exposed mice. However, airway responsiveness to acetyl-β-methylcholine chloride (methacholine) was significantly diminished in IL-11Rα1-deficient as compared with wild-type mice after O3 exposure. In conclusion, these results demonstrate that IL-11Rα1 minimally contributes to lung inflammation but is required for maximal airway responsiveness to methacholine in a mouse model of nonatopic asthma.

Current Asthma Prevalence Using Methacholine Challenge Test in Korean Children from 2010 to 2014

BACKGROUND

Most epidemiological studies depend on the subjects' response to asthma symptom questionnaires. Questionnaire-based study for childhood asthma prevalence may overestimate the true prevalence. The aim of this study was to investigate the prevalence of "Current asthma" using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and methacholine challenge test in Korean children.

METHODS

Our survey on allergic disease included 4,791 children (age 7-12 years) from 2010 to 2014 in Korean elementary schools. Bronchial hyperresponsiveness (BHR) was defined as provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20) ≤ 16 mg/mL. "Current asthma symptoms" was defined as positive response to "Wheezing, current," "Treatment, current," or "Exercise, current." "Current asthma" was defined when the subjects with "Current asthma symptoms" showed BHR on the methacholine challenge test or had less than 70% of predicted FEV1 value.

RESULTS

The prevalence of "Wheezing, ever," "Wheezing, current," "Diagnosis, ever," "Treatment, current," "Exercise, current," and "Current asthma symptoms" was 19.6%, 6.9%, 10.0%, 3.3%, 3.5%, and 9.6%, respectively, in our cross-sectional study of Korean elementary school students. The prevalence of BHR in elementary school students was 14.5%. The prevalence of BHR in children with "Wheezing, ever," "Wheezing, current," "Diagnosis, ever," "Treatment, current," and "Exercise, current" was 22.3%, 30.5%, 22.4%, 28.8%, and 29.9%, respectively. BHR was 26.1% in those with "Current asthma symptoms." The prevalence of "Current asthma" was 2.7%.

CONCLUSIONS

Our large-scale study provides 2.7% prevalence of current asthma in Korean elementary school children. Since approximately one third of the children who have "Current asthma symptoms" present BHR, both subjective and objective methods are required to accurately predict asthma in subjects with asthma symptoms.

Effects of inhaled L-arginine administration in a murine model of acute asthma

Increased arginase activity in the airways decreases L-arginine and causes deficiency of bronchodilating and anti-inflammatory nitric oxide (NO) in asthma. As, it is suggested that L-arginine may have therapeutic potential in asthma treatment, we aimed to investigate the effects of inhaled L-arginine on oxygen saturation (SaO₂) and airway histology in a murine model of acute asthma. Twenty eight BALB/c mice were divided into four groups; I, II, III and IV (control). All groups except the control were sensitized and challenged with ovalbumin. After establishement of acute asthma attack by metacholine administration, the mice were treated with inhaled L-arginine (Group I), saline (Group II) and budesonide (Group III), respectively. SaO₂was measured by pulse oximeter just before and 5 min after methacholine. A third measurement of SaO₂was also obtained 15 min after drug administration in these study groups. Inflammation in the lung tissues of the sacrificed animals were scored to determine the effects of the study drugs. The number of eosinophils in bronchoalveolar lavage (BAL) was determined. The results indicated that inflammatory scores significantly improved in groups receiving study drugs when compared with placebo and L-arginine was similar in decreasing scores when compared with budesonide. SaO₂had a tendency to increase after L-arginine administration after acute asthma attack and this increase was statistically significant (p=0.043). Eosinophilia in BAL significantly reduced in group receiving L-arginine when compared with placebo (p<0.05). Thus in this study we demonstrated that L-arginine improved SaO₂and inflammatory scores in an acute model of asthma.

Bronchodilator effect of Ipraterol on methacholine-induced bronchoconstriction in asthmatic patients

BACKGROUND

The addition of ipratropium, a synthetic cholinergic antagonist, to beta2-agonist therapy provides an additive improvement in adult with acute severe asthma and COPD because of increased vagal tone in the airways. We asked whether ipratropium in combination with fenoterol (Ipraterol) improved pulmonary function in comparison with original Berodual.

MATERIAL AND METHOD

In order to determine the effects of nebulized a single dose of Ipraterol, the study was conducted in a double-blind, randomized and crossover manner by comparing the effect of nebulized a single dose of Berodual on methacholine-induced bronchoconstriction. The study consisted of an 1-week run-in phase and two study visits separated by a washout period of 7 days.

PATIENTS

We studied 20 patients who ranged from 18 to 80 years of age and had mild to moderate persistent asthma.

RESULTS

Nebulized Ipraterol provided a rapid onset of bronchodilation effect similar to nebulized Berodual within 5 minutes by significantly increasing FEV, from 1.19 L to 1.73 L (p < 0.001) and from 1.19 to 1.69 L (p = 0.0001), respectively. This effect of Ipraterol lasted as long (up to 6 hours) and was similar to that of Berodual. The absolute FEV1 values at 360 min after Ipraterol treatment was still higher than the baseline values. We also found that there were no significant differences in the degree of improvement in FEV1 and hypokalemia following treatment with Ipraterol and Berodual.

CONCLUSION

Our data suggest that nebulized Ipraterol offers a statistically significant improvement in pulmonary function without significant systemic absorption causing hypokalemia, with the improvement being comparable to that achieved with nebulized Berodual.

Suppression of the asthmatic phenotype by ultraviolet B-induced, antigen-specific regulatory cells

BACKGROUND

Over recent decades, there has been a significant global increase in the prevalence of asthma, an inflammatory disease of the respiratory system. While ultraviolet radiation (UV) has been used successfully in the treatment of inflammatory conditions such as psoriasis, studies of UV-induced regulation of allergic respiratory responses have been rare, and have not analysed in vivo measurements of airway hyperresponsiveness (AHR) or the antigen specificity of the UV-induced effects.

OBJECTIVE

To investigate the regulatory properties of erythemal ultraviolet B (UVB) irradiation of the skin and the induction of allergen-induced airway immunity in a murine asthma model, and to examine the mechanisms involved.

METHODS

BALB/c mice were exposed to a single erythemal dose of UV 3 days before intraperitonial sensitization (day 0) and boost (day 14) with the antigen, ovalbumin (OVA). Airway-associated, asthma-like responses to aerosolized OVA at day 21 were analysed including (a) AHR measured in vivo, (b) OVA-specific proliferative responses and cytokine production by cells from the lung-draining lymph nodes (LDLN), and (c) inflammatory cells and cytokines in the bronchoalveolar lavage fluid. To determine UVB-induced mechanisms of regulation, LDLN cells from UVB irradiated, OVA-sensitized mice were adoptively transferred into naïve BALB/c mice that were subsequently sensitized and challenged with OVA, or a non-specific antigen.

RESULTS

UVB irradiation of skin significantly suppressed AHR to methacholine and OVA-specific responses in the LDLN and in the lung compartment. Reduced OVA-specific responses by LDLN cells from both UVB irradiated mice and mice that received 5 x 10(6) LDLN cells from UVB irradiated, but not from non-irradiated, OVA-sensitized mice suggested that UVB-induced regulatory cells are responsible for many of the asthma-reducing effects of dorsal UVB exposure.

CONCLUSION

UVB irradiation of skin suppresses AHR and cellular responses of the airways to respiratory allergens. Further, this study implicates UVB or its downstream mediators as a potential approach to reducing the severity of asthma.

Asthma definitions, relative validity and impact on known risk factors in young Brazilians

BACKGROUND

An asthma score was proposed in the European Community Respiratory Health Survey (ECRHS) framework, as dichotomous definitions could be less appropriate in the study of chronic diseases. The aims of this study were to assess the value of this asthma score in comparison with other definitions of asthma in another population setting, using as criteria bronchial hyperresponsiveness (BHR) to methacholine and diagnosed asthma, and the association of these definitions to known risk factors of asthma.

METHODS

We used the ECRHS questionnaire on 2063 Brazilians, aged 23-25 years, and measured their BHR. We assessed the positive and negative likelihood ratios (PLR and NLR) of the asthma score (0-8), a three question score (ECRHS definition) and single asthma symptoms in relation to BHR and diagnosed asthma.

RESULTS

The PLR were relatively low for all asthma definitions with odd ratios varying from 1.47 for asthma score to 5.50 for wheeze and waking with breathlessness without a cold. The NLR were near 1. The PLR were lower for assessments using the score than for dichotomous assessments or the ECRHS definition. The PLR increased with asthma scores, but the prevalence with higher scores was too low for useful analysis. The asthma score was slightly better for identifying associations from a set of known risk factors than the other two approaches.

CONCLUSION

Our study provided little support for a greater validity of this asthma score over other asthma definitions, and only marginal advantage for identifying risk factors.

Lower respiratory tract complications during nasal provocation: nonspecific stimulant or specific allergen?

BACKGROUND

Allergic rhinitis (AR) is an allergic inflammatory disease in which allergen exposure leads to the appearance of symptoms in sensitized individuals because of histamine liberation from nasal mucosal mast cells. Comorbidity of this disease with allergic asthma is common. Therefore, the one airway one disease theory has been put forward. Lower respiratory tract provocation tests with both nonspecific (methacholine) and specific stimulants (allergen) have yielded positive results in nonasthmatic patients with AR. However, not enough research is available to demonstrate whether there is a response in the lower respiratory tract during nasal provocation tests (NPTs) performed to evaluate only nasal airway in these patients.

OBJECTIVES

To determine if the lower respiratory tract was affected as a result of NPTs with nonspecific and specific stimulants in nonasthmatic patients with AR and to determine the frequency of lower respiratory tract obstruction due to NPT with nonspecific and specific stimulants.

METHODS

Thirty-six participants were enrolled in the study between November 2005 and January 2006 (18 AR patients and 18 healthy control subjects). Patients underwent 2 sessions of NPT. The first session was performed with nasal methacholine as a nonspecific stimulant, and the second session was performed with nasal Olea europaea extract as a specific stimulant. The control group underwent only nonspecific nasal provocation with methacholine. Basal nasal opening and nasal pressures were evaluated spirometrically by rhinomanometric measurements and basal respiratory function tests in both groups before methacholine nasal provocation. Whether or not nasal provocation was achieved, spirometric measurements were performed in all patients and controls after NPTs.

RESULTS

NPTs with methacholine resulted in a similar frequency of nasal provocation in the patient and control groups (P = .63). However, the mean methacholine dose was lower in patients with AR (P = .049). There was a decrease in parameters of asthma, including the ratio of forced expiratory volume in 1 second to forced vital capacity (P = .04), peak expiratory flow (P = .01), and forced expiratory flow between 25% and 75% (P = .004), as a result of NPTs with methacholine in the patient group. However, NPTs with allergen did not cause a change in lower respiratory tract obstruction criteria.

CONCLUSIONS

Lower respiratory tract obstruction can occur after NPTs with nonspecific stimulants; therefore, tests performed with specific allergens can be regarded as safer.

Methacholine challenge testing: identifying its diagnostic role, testing, coding, and reimbursement

Methacholine challenge testing (MCT), also sometimes described as bronchoprovocation testing, is widely performed for both research and diagnostic purposes. MCT is clinically useful when the patient presents with a history of symptoms suggesting asthma, but spirometry findings are normal. Typically, MCT is performed in a pulmonary function laboratory, a clinic, or a physician's office. MCT requires time, effort, and understanding. Two standard testing regimes are identified along with proper coding and reimbursement methodologies.

Glycopyrrolate causes prolonged bronchoprotection and bronchodilatation in patients with asthma

INTRODUCTION

Inhaled anticholinergic drugs are effective bronchodilators in the treatment of COPD, and tiotropium bromide has recently been introduced as a once-daily bronchodilator for use as a maintenance treatment. Racemic glycopyrrolate is an anticholinergic drug that has been used orally to control gastric acidity, parenterally as an antisialogogue and to reverse neuromuscular blockade, and has been studied by inhalation for asthma and COPD.

DESIGN AND OBJECTIVE

We investigated the duration of protection against the constrictor effects of inhaled methacholine of a single dose of inhaled nebulized racemic glycopyrrolate (0.5, 1.0, and 2.0 mg) compared with ipratropium bromide (0.5 mg) and placebo in 10 atopic asthmatic volunteers in a double-blind, five-way, crossover study.

RESULTS

Protection against methacholine-induced bronchospasm after administering glycopyrrolate was maintained to 30 h, the last time point measured. Both bronchodilatation and bronchoprotection were significantly longer with glycopyrrolate than after ipratropium bromide, and bronchoprotection was significant at all time points from 2 to 30 h compared to placebo. Dryness of the mouth and nose was described in 18% of patients after the highest dose of glycopyrrolate.

CONCLUSIONS

The prolonged bronchodilator response and the protection against methacholine-induced bronchospasm demonstrated in asthma suggests that inhaled racemic glycopyrrolate would be superior to ipratropium bromide for treatment of stable COPD.

Para-Bromophenacyl bromide alleviates airway hyperresponsiveness and modulates cytokines, IgE and eosinophil levels in ovalbumin-sensitized and -challenged mice

Airway hyperresponsiveness, airway eosinophilia and increased IgE levels in serum are the important characteristic features of asthma. We evaluated the potential of para-Bromophenacyl bromide (PBPB), a known phospholipase A(2) inhibitor, on allergen-induced airway hyperresponsiveness in a mouse model. We sensitized and challenged mice with ovalbumin (OVA) to develop airway hyperresponsiveness as assessed by airway constriction and airway hyperreactivity (AHR) to methacholine (MCh) induced by allergen. The mice were orally treated with PBPB (0.1, 1 and 10 mg/kg) during or after OVA-sensitization and OVA-challenge to evaluate its protective or reversal effect on airway constriction and AHR to MCh. Determination of OVA-induced airway constriction and AHR to MCh were performed by measuring specific airway conductance (SGaw) using non-invasive dual-chamber whole body-plethysmography. We observed that PBPB (1 mg/kg) significantly reduced OVA-induced airway constriction and AHR to MCh (p<0.01). PBPB (1 mg/kg) treatment significantly inhibited PLA(2) activity in the BAL fluid. Cytokine analysis of the BAL fluid revealed that PBPB caused an increase in interferon-gamma (IFN-gamma) (p<0.02) and a decrease in interleukin-4 (IL-4) (p<0.05) and interleukin-5 (IL-5) (p<0.05) levels. The OVA-specific serum IgE levels (p<0.01) and the BAL eosinophils (p<0.001) were also reduced significantly. Thus, PBPB is capable of modulating allergen induced cytokine levels and serum IgE levels, and alleviating allergen induced airway hyperresponsiveness and eosinophils in mice. These data suggest that PBPB could be useful in the development of novel agents for the treatment of allergen induced airway hyperresponsiveness.

Predictors for typical asthma onset from cough variant asthma

Cough variant asthma is recognized to be a precursor of asthma or preasthmatic state because nearly 30% patients with cough variant asthma develop typical asthma within several years. However, predictors for risk of typical asthma onset from cough variant asthma are unknown. Forty-one patients with cough variant asthma (median age 50 years, 13 men and 28 women), who had undertaken spirometry, bronchial reversibility test, methacholine provocation test, measurements of peripheral blood eosinophil count, serum total IgE, and specific IgE to common allergens, and induced sputum eosinophil count at presentation, were followed up with special emphasis on typical asthma onset during 1 year or more (median 4 years, range 1-12.4). Long-term inhaled corticosteroids (ICS) were taken in 27 patients. Univariate and multivariate logistic analyses were performed to determine the predictors for typical asthma onset. Asthma onset was recognized in 7 patients. Bronchial hyperresponsiveness, peripheral blood eosinophil count, and no use of ICS were significant predictors for the typical asthma onset by univariate analysis. However, only bronchial hyperresponsiveness was the significant predictor when multivariate analysis was used (adjusted OR 0.028, 95% CI 0.001-0.783, p = 0.0355). Bronchial hyperresponsiveness may be the most important predictor for risk of typical asthma onset from cough variant asthma.

Relationship between airway responsiveness to neurokinin A and methacholine in asthma

Non-adrenergic non-cholinergic (NANC) nerves release bronchoactive tachykinins such as substance P (SP) and neurokinin A (NKA) that can induce features of asthma. The airway response to NKA in humans closely resembles that of methacholine (M). Hence, we investigated the relationship between airway responsiveness to NKA and M in subjects with asthma. To this end, we analyzed baseline data of 27 subjects with mild persistent asthma (20F/7M) 19-46 y; FEV1 81-136% pred.; PC20FEV1 (M)<80 micromol/mL) participating in a proof-of-concept study. All subjects were non-smokers and asthma was controlled by on demand short-acting beta2-agonists only. Dose-response curves to M (0.15-80 micromol/mL) and NKA (3.4 (10(-3))-0.88 micromol/mL) were performed on two separate days, and airway response was measured by FEV1 until a > or = 20% fall from baseline (PC20FEV1). Twenty-two subjects reached a PC20FEV1 on both occasions. The PC20FEV1 values of both agonists correlated significantly (Spearman's r=-0.721; p=0.0002), and the relationship was given by 10log(PC20FEV1(NKA))= -1.36 + (0.60 x 10log(PC20FEV1(M)). We have demonstrated a significant relationship between airway responsiveness to NKA and methacholine in asthma. This suggests that both agonists may share common final pathways in causing bronchoconstriction in patients with mild persistent asthma. Based on our data and previous studies in asthma, it can be hypothesized that this direct NKA-induced bronchoconstrictor response may be mediated by predominant stimulation of the tachykinin NK-2 receptors on airway smooth muscle cells.

Variants in the vitamin D receptor gene and asthma

BACKGROUND

Early lifetime exposure to dietary or supplementary vitamin D has been predicted to be a risk factor for later allergy. Twin studies suggest that response to vitamin D exposure might be influenced by genetic factors. As these effects are primarily mediated through the vitamin D receptor (VDR), single base variants in this gene may be risk factors for asthma or allergy.

RESULTS

951 individuals from 224 pedigrees with at least 2 asthmatic children were analyzed for 13 SNPs in the VDR. There was no preferential transmission to children with asthma. In their unaffected sibs, however, one allele in the 5' region was 0.5-fold undertransmitted (p = 0.049), while two other alleles in the 3' terminal region were 2-fold over-transmitted (p = 0.013 and 0.018). An association was also seen with bronchial hyperreactivity against methacholine and with specific immunoglobulin E serum levels.

CONCLUSION

The transmission disequilibrium in unaffected sibs of otherwise multiple-affected families seem to be a powerful statistical test. A preferential transmission of vitamin D receptor variants to children with asthma could not be confirmed but raises the possibility of a protective effect for unaffected children.

Heterogeneity of narrowing in normal and asthmatic airways measured by HRCT

Asthmatic airway narrowing is heterogeneous and contributes to airway hyperresponsiveness. The present study compared heterogeneity of narrowing during methacholine challenge in asthmatics and normal subjects using high-resolution computed tomography (HRCT). The current authors defined heterogeneity as variability in narrowing greater than the repeatability of measurement. Airways of <2 mm diameter were compared with larger airways from baseline and postmethacholine HRCT of the right lower lung in 13 normals (seven had repeat baseline scans) and seven asthmatics. The coefficient of repeatability was calculated from repeat scans (RepAi) and was compared with heterogeneity of narrowing measured by the variability in narrowing from pre versus postmethacholine scans (VardeltaAi). Forced expiratory volume in one second decreased 27+/-6% and 24+/-8% in normals and asthmatics, respectively. Airways >2 mm narrowed more heterogeneously in asthmatics (VardeltaAi=+/-0.85 mm) compared with normals (VardeltaAi=+/-0.67 mm), with both being greater than the measure of repeatability (RepAi=+/-0.16 mm). Small airway narrowing was not heterogeneous in asthmatics (VardeltaAi=+/-0.59 mm) or normals (VardeltaAi=+/-0.53 mm) compared with repeatability (RepAi=0.51 mm). It is possible to study heterogeneity of airway narrowing in small and large airways using high resolution computed tomography. Airway narrowing is heterogeneous in the large airways of asthmatics and normals, being greater in asthmatics.

Sputum eosinophil counts and eosinophil cationic protein levels in cough-variant asthma and in classic asthma, and their relationships to airway hypersensitivity or maximal airway response to methacholine

BACKGROUND

The aims of this study were to compare the degree of airway inflammation in cough-variant asthma (CVA) with that in classic asthma (CA), and to examine the relationship between airway inflammation and airway hypersensitivity or maximal airway response to methacholine in both conditions.

METHODS

Sputum was induced in 41 CVA patients, in 41 methacholine PC(20)-matched CA patients, and in 20 healthy children. The sputum samples were analyzed for total and differential cell counts, and for eosinophilic cationic protein (ECP). A high-dose methacholine challenge test was performed in CVA and CA patients to determine PC(20) and maximal airway response.

RESULTS

Sputum eosinophil percentages and ECP levels were significantly elevated in CVA and CA vs the control, but no significant differences were found between the two asthma groups. In the two asthma groups, neither sputum parameters correlated significantly with methacholine PC(20). However, the absence of a maximal response plateau or its higher level, when present, was associated with increased eosinophil percentages and ECP levels in the CVA group.

CONCLUSIONS

The degree of eosinophilic inflammation may not be causally related to differences in presented asthma manifestations. The identification of a maximal response plateau and the level of this plateau in patients with CVA may provide information pertinent to airway eosinophilic inflammation.

Greater involvement of neurokinins found in Guinea pig models of severe asthma compared with mild asthma

BACKGROUND

Involvement of neurokinins in asthma has been previously pointed out by several reports. However, the relationship between neurokinins and the severity of asthma has remained unclear. We developed a model of mild asthma (model I) and severe asthma (model II) in guinea pigs, and investigated the function of neurokinins in both models.

METHODS

In models I and II, systemically sensitized guinea pigs were made to inhale ovalbumin once and three times, respectively. Substance P (SP) and neurokinin A (NKA) concentrations in the bronchoalveolar lavage fluid (BALF) were measured in models I and II. Then, the effects of a capsaicin pretreatment, which depletes neurokinins, in both animal models on airway narrowing induced by the last ovalbumin inhalation, airway hyperresponsiveness to inhaled methacholine, and eosinophil accumulation in BALF, were investigated.

RESULTS

SP concentration tended to increase and the NKA concentration increased significantly in model II, but not in model I. Capsaicin pretreatment significantly inhibited the late bronchial response that was observed 2-6 h after the last ovalbumin inhalation, airway hyperresponsiveness and eosinophil accumulation in model II. On the other hand, it had no effects on the responses in model I.

CONCLUSION

It is suggested that the more severe the disease, the greater the involvement of neurokinins.

Recovery of methacholine responsiveness after end of exposure in occupational asthma

Recent data suggest that responsiveness to methacholine continues to improve 2 and more years after cessation of exposure to agents causing occupational asthma (OA). The goal of this study was to characterize further the curve of improvement to methacholine responsiveness in subjects with OA. Eighty subjects with confirmed OA who had at least two assessments of a provocative concentration of histamine causing a 20% drop in FEV(1) (PC(20)) and were seen for at least 2 years after cessation of exposure. The shape of recovery of PC(20) was assessed by CARMA (James K. Lindsey, Liège, Belgium) analysis. Slopes of recovery were compared in the first 2.5 years in 55 subjects and from 2.5 years until the end of observation in 56 subjects. Recovery curves showed progressive improvements in PC(20) significantly influenced by time lapse since end of exposure, sex, baseline PC(20), and FEV(1). The slopes of recovery were significantly different from zero both for the first 2.5 years after cessation of exposure (0.27 +/- 0.05 SEM natural logarithm of PC(20) per year) and later (0.09 +/- 0.008 SEM natural logarithm of PC(20) per year), with the slope significantly steeper for the first 2.5 years. This study shows that improvement in responsiveness to methacholine continues for years after cessation of exposure but that the improvement is more rapid in the first 2.5 years.

Aerosolized anti-T-cell-receptor antibodies are effective against airway inflammation and hyperreactivity

Aerosolized monoclonal antibodies (mAbs) specific for T-cell receptors (TCR) were used to manipulate T-cell function in airways of ovalbumin (OVA)-sensitized and -challenged mice with airway hyperresponsiveness (AHR). The inhaled mAbs were found to be effective at low doses, had little or no systemic effect and specifically abrogated both effector and regulatory functions of the targeted T cells. Specific mAbs targeting alphabeta T cells suppressed and those targeting gammadelta T cells enhanced AHR. Moreover, specific mAbs directed against subsets of gammadelta T cells varied in their effect on AHR. Using this approach of targeting either alphabeta or gammadelta T cells reduced airway eosinophila, although the effect of mAbs specific for alphabeta T cells was stronger. The use of aerosolized anti-TCR mAbs may offer an effective approach for the treatment of airway inflammation and AHR.

Sputum CD34+IL-5Ralpha+ cells increase after allergen: evidence for in situ eosinophilopoiesis

Eosinophil lineage-committed progenitors increase in the bone marrow of subjects with asthma developing allergen-induced airway hyperresponsiveness and eosinophilia. Also, higher numbers of circulating eosinophil/basophil cfu have been demonstrated 24 hours after allergen inhalation and in bronchial and nasal biopsies of allergic individuals. These cells may undergo in situ eosinophilopoiesis, suggesting that after allergen inhalation, progenitor cells traffic from the bone marrow to the airways, providing an ongoing source of effector cells. To examine this possibility, CD34(+) and CD34(+)IL-5Ralpha(+) cells were measured in induced sputum from allergic subjects with asthma at baseline and at 7 and 24 hours after allergen and diluent inhalation, using flow cytometry. Isolated early responders (n = 9) were contrasted to dual responders (n = 9), who develop allergen-induced sputum and blood eosinophilia and airway hyperresponsiveness, and to normal control subjects. At baseline, there were significantly fewer sputum eosinophils and CD34(+) cells in normal control subjects compared with subjects with asthma. Sputum CD34(+) cells increased at 7 hours after allergen inhalation in both groups of subjects with asthma, which was sustained at 24 hours in the dual responder group only, associated with sustained increases in sputum CD34(+)IL-5Ralpha(+) cells, eosinophils, and interleukin-5. These results indicate that eosinophil progenitors can migrate to the airways and may differentiate toward an eosinophilic phenotype.

Safety and tolerability of methacholine challenge in infants with recurrent wheeze

Bronchial hyperreactivity (BHR) is a key feature of asthma, but measurement can usually not be achieved in infants with standard lung function tests. We investigated the safety and tolerability of methacholine challenge in infants with recurrent wheezing episodes. 78 methacholine challenges in 51 sedated infants aged 12-36 months with recurrent wheezing episodes were performed. Methacholine challenge was stopped when clinical signs (coughing, wheezing, or cyanosis) or a drop of oxygen saturation (SPO2) of at least 5% or a drop of transcutaneous oxygen tension (PtcO2) of at least 0.8 kPa or an increase of resistance (RrsSO), of 50% by single occlusion technique were observed. Prior to methacholine challenge, all children were symptom-free with a mean SPO2 of 97.4% (SD 1.80%). In 48 cases (61.5%), no clinical sign was observed, 17 (21.8%) coughed, and 13 (16.7%) wheezed. A mean reduction of SPO2 of 5.0% (SD 3.89%) for the entire population was observed. In 15 of 78 cases, a decrease of SPO2 <90% occurred. This SPO2 drop was short-lasting and resolved spontaneously or after bronchodilator inhalation. Infants whose SPO2 dropped <90% showed a greater increase of RrsSO compared to infants who did not drop <90% (133% vs. 65% RrsSO increase, p<0.001). Methacholine challenge, using a combination of clinical observation, monitoring of SPO2 and PtcO2, and airway resistance using the single-occlusion technique, is a safe and tolerable tool to measure the BHR in infants with recurrent wheezing episodes.

Recall helper T cell response: T helper 1 cell-resistant allergic susceptibility without biasing uncommitted CD4 T cells

Effector and memory T lymphocytes differ significantly, and there is no experimental evidence that memory cells are sufficient to render an otherwise normal individual susceptible to localized allergic inflammation. Furthermore, nothing is known about the kinetics of memory responses after inhalation of antigen or interplay between an allergen-specific memory helper T (Th) cell Th2 population and uncommitted or competing Th1 cells. To study these processes, T cell receptor-transgenic CD4(+) effector cells were generated in vitro, transferred into naive recipients, and allowed to resume a quiescent state. Inhalation of protein antigen reactivated these Ag-specific Th2 donor cells, leading to allergic pulmonary inflammation and airway hyperreactivity. Susceptibility was correlated with the size of the input Th2 population, but Th1 cells neither enhanced nor reduced inflammation in this model. Importantly, the reactivation of these antigen-experienced cells by inhaled antigen did not skew the cytokine balance of recipient-derived T cells recruited to the lung nor did it inhibit the development of donor-derived Th1 cells from uncommitted antigen-experienced cells that form a normal part of immune responses. These data indicate that a quiescent memory Th2-cell population can create susceptibility to allergic pulmonary inflammation in a manner refractory to inhibition by Th1 cells or endogenous inhibitory mechanisms.

A comparison of salmeterol and formoterol in attenuating airway responses to short-acting beta2-agonists

In vitro data suggest that salmeterol, contrary to formoterol, can partly antagonise the effect of short-acting beta(2)-agonist rescue medication. To explore whether this occurs in vivo, we compared the effects of increasing doses (200-3200 microg) of fenoterol on the recovery of methacholine induced bronchoconstriction as well as PD(20) methacholine in 23 asthmatic patients, during two-week treatment periods with placebo, and standard doses of salmeterol or formoterol in a double blind, double-dummy, crossover study. Salmeterol showed a slightly higher propensity for the development of bronchodilator tolerance. The recovery of methacholine induced bronchoconstriction was more complete during regular use of formoterol relative to salmeterol. During regular use of both long-acting beta(2)-agonists the bronchoprotective efficacy of fenoterol was attenuated, but this was more pronounced during salmeterol than during formoterol. The mean maximum increase in PD(20) metacholine after the highest dose of fenoterol was 3.97 DD during placebo, 2.47 DD during formoterol (p<0.001) and 1.81 DD during salmeterol treatment (p<0.001). We conclude that in asthmatic patients the efficacy of short-acting beta(2)-adrenoceptor agonists can be significantly attenuated during regular use of long-acting beta(2)-agonists. In this respect, differences were observed between salmeterol and formoterol that may represent the expression of partial antagonism by salmeterol.

Cardiac arrhythmia monitoring during bronchial provocation test with methacholine

STUDY OBJECTIVES

During a bronchial provocation test (BPT), the performance of maximal inspiratory-expiratory maneuvers, causing abrupt and marked shifts in intrathoracic pressure, may increase the risk of cardiac arrhythmias. Moreover, the inhalation of methacholine (MCh), a cholinergic agonist agent, could favor the development of unwelcome cardiovascular events, namely, cardiac arrhythmias.

SUBJECTS AND METHODS

We studied the number and severity of cardiac arrhythmias by ECG-Holter monitoring before, during, and after BPTs with MCh challenge in a group of 46 consecutive nonselected subjects (28 men and 18 women) with clinical indications for BPT, without preexisting cardiovascular diseases, and not receiving arrhythmogenic drugs. The subjects performed a routine pulmonary function test (PFT), followed by BPT, during ECG-Holter monitoring. Determination of the serum potassium concentration, a baseline arterial blood gas analysis, and monitoring of oxyhemoglobin saturation also were performed.

RESULTS

We found no significant increase in the number of supraventricular and ventricular arrhythmias during the performance of PFTs and of BPTs with MCh in the subjects, either with or without bronchial hyperresponsiveness (BHR). However, during the performance of BPTs, we observed a significant reduction in mean heart rate.

CONCLUSIONS

Our results indicate that the performance of PFTs and BPTs with MCh does not increase the cardiac arrhythmogenic risk in subjects without cardiovascular diseases, as well as in those with BHR, suggesting that these tests are safe to perform in most subjects.

Absence of deep inspiration-induced bronchoprotection against inhaled allergen

Deep inspiration-induced bronchoprotection appears to be a major mechanism through which airway obstruction by spasmogens is avoided. Loss of bronchoprotection is associated with airway hyper-responsiveness. Individuals with allergic rhinitis and no airway hyperresponsiveness develop obstruction after allergen inhalation. To test the hypothesis that deep inspiration-induced bronchoprotection is not active against allergic reactions, we performed four single-dose bronchial challenges, two with methacholine and two with allergen, on 10 subjects with allergic rhinitis. Without deep inspirations, the methacholine-induced reduction in FEV1 from baseline was 36.9 +/- 3.6% (mean +/- SEM); this was attenuated to 15.0 +/- 2.0 when five deep inspirations preceded methacholine inhalation (p = 0.0001). When allergen was inhaled, the reduction in FEV1 was 24.7 +/- 2.9% and 28.8 +/- 6.4% without and with deep inspirations, respectively. We conclude that bronchoprotection by deep inspirations is absent against allergic reactions. Understanding the cause of this phenomenon may shed light into the pathogenesis of airway hyperresponsiveness in allergic asthma.

Childhood cough variant asthma and its relationship to classic asthma

BACKGROUND

In pediatrics, some patients with chronic cough who have no evidence of a causative disease are diagnosed as having cough variant asthma (CVA). The precise prognosis of infants and children with CVA, however, is still unclear.

OBJECTIVE

To evaluate the relationship between CVA and classic asthma in childhood.

METHODS

To diagnose CVA, we performed a methacholine inhalation challenge with use of a transcutaneous oxygen pressure (tcPO2) monitoring system in 100 children with chronic cough, and 75 children (45 boys and 30 girls; mean age, 5.7 years) were diagnosed as having CVA. These patients underwent follow-up monitoring for more than 3 years to ascertain whether classic asthma developed. For comparison, 53 age-matched children with classic asthma (30 boys and 23 girls; mean age, 5.6 years) and 30 age-matched control subjects (12 boys and 18 girls; mean age, 5.5 years) also participated in this study. Consecutive doses of methacholine were doubled until a 10% decrease in tcPO2 from the baseline was reached. The cumulative dose of methacholine at the inflection point of tcPO2 (Dmin-PO2) was considered to represent the sensitivity of tcPO2 to inhaled methacholine.

RESULTS

After 3 years or more of follow-up assessments, 52 of the 75 patients answered our questionnaire. Of the responding patients, 28 had been diagnosed as having classic asthma. A significant difference was noted in the age at onset of CVA between the children in whom classic asthma developed (the asthma-developed group) and those in whom classic asthma did not develop (the asthma-free group). No statistically significant differences in Dmin-PO2 between the asthma-developed group and the asthma-free group or between the girls and the boys, however, were foun

CONCLUSIONS

This study showed that 75% of children with chronic cough had CVA, that classic asthma developed in 54% of the children with CVA, and that it is not the severity of bronchial hyperresponsiveness in CVA but the age at onset of CVA that is a risk factor for the development of classic asthma in childhood CVA.

Neurotensin pulmonary metabolism in normal and asthmatic subjects

BACKGROUND

The role of pulmonary metabolism of endogenous neurotensin (NT) in asthma is still unclear. Information on this subject in humans is scarce.

OBJECTIVES

Evaluation of the pulmonary metabolism of the endogenous NT in asthmatic subjects during symptom-free periods and after a methacoline challenge test and in healthy individuals.

METHODS

Ten asthmatic subjects (aged 34 to 70 years), diagnosed with extrinsic (n = 5), atopic (n = 3), and mixed asthma (n = 2), were compared to a group of 10 healthy individuals (aged 45 to 69 years). The asthmatic group of patients was evaluated with a PD20-FEV1 methacoline challenge test 3 days after a washout period from cessation of their regular medications. Two catheters were inserted in order to draw blood samples for the evaluation of NT concentration: one was inserted into the pulmonary artery and the other into the radial artery. The mean concentration of NT in pulmonary and systemic arterial blood, as well as the arteriovenous difference of NT and the absolute value of production rate [PR/m'], PR/m'/kg and PR/m'/m2 were calculated for each participant.

RESULTS

The mean neurotensin concentration in normal subjects was higher in mixed venous blood (pulmonary artery) than in systemic arterial blood (p < 0001). Similarly, mean NT mixed venous levels in asthmatic subjects was shown to be higher than mean NT levels in systemic arterial blood, before and after the bronchoconstriction with methacoline (p = 0.05 and p = 0.02, respectively). In contrast, the arterovenous difference and the mean values of PR of NT were similar in both groups.

CONCLUSIONS

Our findings suggest that (1) NT concentration in mixed venous blood changes in transit through the pulmonary parenchyma, indicating that the pulmonary parenchyma is an important site of NT metabolism; (2) Pulmonary clearance of NT is unaffected by cholinergic bronchoconstriction. Further clinical studies are needed in order to improve both the understanding and the therapeutic approach of the neurogenic process in asthmatic subjects.

Airway obstruction induced by inhaled acetaldehyde in asthma: repeatability relationship to adenosine 5'-monophosphate responsiveness

Inhaled acetaldehyde and adenosine 5'-monophosphate (AMP) cause bronchoconstriction in asthmatics by a mechanism believed to involve histamine release from airway mast cells. This study investigates the repeatability of the acetaldehyde challenge and the relationship between airway responsiveness to acetaldehyde and AMP. To this end, we examined the effect of inhaled acetaldehyde on airway tone in comparison with either methacholine or AMP in 16 asthmatics. Furthermore, the repeatability of the acetaldehyde challenge was assessed in 14 subjects with mild asthma. The response to each bronchoconstrictor agent was measured by the PC20 (provocative concentration required to produce a 20% fall in FEV1). The geometric mean (range) PC20 values were 3.1 mmol/l (0.5-46.0 mmol/l) for methacholine, 883.1 mmol/l (190.7-1816.1 mmol/l) for acetaldehyde, and 50.1 mmol/l (3.2-1152.1 mmol/l) for AMP. Thus, acetaldehyde was 18-fold less potent than AMP in causing bronchoconstriction. A similar correlation was observed between PC20 acetaldehyde and either PC20 AMP (r = 0.58, p = 0.02) or PC20 methacholine (r = 0.56, p = 0.02). The challenge procedure with acetaldehyde was moderately repeatable (coefficient of repeatability = +/- 1.4 doubling concentrations, intraclass correlation coefficient = 0.64). We conclude that inhaled acetaldehyde is less potent than AMP in causing bronchoconstriction in asthma, and that the response to inhaled acetaldehyde is repeatable. Furthermore, the present data lends indirect support to the suggestion that acetaldehyde responsiveness and AMP responsiveness are not identifying the same alterations in the airways.

Relationship of skin-prick reactivity to aeroallergens and hyperresponsiveness to challenges with methacholine and adenosine monophosphate

BACKGROUND

Clarification of the relationship between atopy and bronchial hyperresponsiveness (BHR), both key features of asthma, is critical to our understanding of the disease. We therefore investigated the putative relationship between skin-prick reactivity to aeroallergens and BHR to direct and indirect stimuli.

METHODS

We performed a retrospective analysis of data from 332 patients presenting with a diagnosis of asthma. Patients were characterized by skin prick tests (SPT), spirometry and bronchial challenge with methacholine and adenosine monophosphate (AMP).

RESULTS

For patients who had BHR to methacholine but not AMP, the presence of atopy was associated with a lower PD20 (the provocative dose of methacholine producing a fall in FEV1 of 20%), amounting to a geometric mean (95% confidence interval (CI)) of 2.3-fold (1.4-4.0) difference. Furthermore, the number of skin-prick positive (SPP) responses was related to methacholine reactivity: 0-1 SPP, PD20 = 69.9 micro g; 2-4 SPP, PD20 = 47.8 micro g; 5-8 SPP, PD20 = 35.6 micro g. There was a 2.0- fold (1.1-3.6) difference between the groups with a low (0-1 SPP) and high (5-8 SPP) degree of skin-prick reactivity. A similar pattern was seen when data were analyzed including only perennial allergens. Spirometry was unrelated to the degree of skin-prick reactivity.

DISCUSSION

These results suggest that skin-prick reactivity to aeroallergens is associated with BHR to methacholine.

Vocal cord dysfunction induced by methacholine challenge testing

STUDY OBJECTIVES

To determine whether methacholine challenge testing (MCT) provokes vocal cord dysfunction (VCD), as evidenced by inspiratory vocal cord closure on direct laryngoscopy, and whether spirometry and flow-volume loops (FVLs) demonstrate any changes that are suggestive of VCD.

DESIGN

Prospective, controlled study.

SETTING

Army medical center.

PATIENTS

Thirty-four subjects all with normal baseline spirometry. Ten subjects had documented evidence of VCD, 12 subjects had exercise-induced asthma (EIA) and reactive MCT, and 12 subjects served as healthy asymptomatic control subjects.

METHODS

Measurement of spirometry with FVLs and direct laryngoscopy of the vocal cords performed immediately before and after subjects had undergone MCT.

RESULTS

Evidence of inspiratory vocal cord adduction was found in four VCD patients. Two patients had adducted vocal cords at baseline, and their conditions were unchanged after undergoing MCT. Two other patients had normal conditions at baseline and demonstrated acute inspiratory vocal cord adduction after undergoing MCT. None of the patients in the EIA or control groups had evidence of VCD at baseline or after undergoing MCT. Truncation of the inspiratory limb of the FVL after MCT was noted in five patients, which correlated with evidence of VCD in 60% of these patients. One EIA patient had truncation of the inspiratory FVL after MCT, and no changes were found in the control group. A comparison of spirometry between EIA patients and VCD patients with and without evidence of inspiratory vocal cord adduction during MCT showed no significant differences.

CONCLUSIONS

The findings suggest that MCT may cause an acute episode of vocal cord adduction and that positive results may not reflect underlying reactive airways disease. However, a flattening or truncation of the inspiratory FVL after the patient undergoes MCT is not diagnostic for the presence of inspiratory vocal cord adduction.

Childhood farm environment and asthma and sensitization in young adulthood

BACKGROUND

Farm environment in childhood may protect against sensitization, allergic rhinitis, and asthma.

METHODS

Subjects were obtained from 10 667 Finnish first-year university students who responded to a questionnaire survey on IgE-mediated diseases. Two random samples were selected from 1631 respondents in Turku: subjects with asthma or wheezing, and subjects without asthmatic symptoms. A total of 296 subjects (72%) participated. Skin prick tests (SPT), measurements of IgE-antibodies, methacholine challenge, and bronchodilation tests were performed. Weighted occurrence of current asthma and sensitization among students from "childhood farm" and "childhood nonfarm" environments were analyzed.

RESULTS

Current asthma was found in 3.1% of subjects with childhood farm environment, and in 12.4% with nonfarm environment (odds ratio (OR) 0.22; 95% confidence interval (CI) 0.07-0.70). There were fewer positive SPT to birch (8.3 vs. 24.2%, OR 0.28, 95% CI 0.07-1.15) and timothy pollen (12.6 vs. 30.3%, OR 0.33, 95% CI 0.09-1.20) among subjects with childhood farm environment, but more sensitization to house-dust mite (22.0 vs. 4.9%, OR 5.43, 95% CI 1.60-18.46). Sensitization to cat (RAST class >/= 3) was less common in subjects with farm compared to nonfarm environments in childhood (1.5 vs. 13.1%; OR 0.10, 95% CI 0.02-0.47).

CONCLUSIONS

Farm environment in childhood protects against adult asthma and sensitization-especially to cat-the most important asthma related allergen. In contrast, sensitization to house-dust mite was more common in farming subjects.

The importance of maximal airway response to methacholine in the prediction of wheezing development in patients with cough-variant asthma

BACKGROUND

A significant proportion of patients diagnosed with cough-variant asthma eventually manifest classic asthma signs, such as wheezing and dyspnea. The aim of this study was to investigate whether the degree of airway hypersensitivity and/or the level of maximal airway response can predict the development of wheezing in subjects with cough-variant asthma.

METHODS

At study initiation, a high-dose methacholine inhalation test was performed to measure provocative concentration causing a 20% fall (PC20) in forced expiratory volume in 1 s (FEV1) and maximal airway response. Each person was evaluated regularly every 3 months for 4 years and also on the occasion of wheezing being perceived for the first time.

RESULTS

Of the 48 patients available in the follow-up period, 21 (Group 1) developed clinical wheezing, while 27 (Group 2) did not. There was no significant difference in PC20 levels between the two groups. The level of maximal airway response, however, was significantly higher in Group 1 than in Group 2. The score test for trend revealed a significant association between the future development of wheezing and the level of maximal airway response (P = 0.007), but not the level of methacholine PC20 (P = 0.423).

CONCLUSIONS

The level of maximal airway response, rather than the degree of airway hypersensitivity, may be an important risk factor for the future development of classic asthma in patients with cough-variant asthma.

Effects of bronchial obstruction on lower esophageal sphincter motility and gastroesophageal reflux in patients with asthma

The relationship between gastroesophageal reflux and asthma remains unclear. The aim of this study was to analyze the effect of bronchial obstruction on lower esophageal sphincter (LES) motility and reflux in patients with asthma. LES motility and esophageal pH were assessed in eight subjects with intermittent asthma and eight healthy volunteers during three consecutive 30-minute periods: baseline, methacholine-induced bronchospasm, and after inhalation of the beta2-agonist salbutamol. Healthy subjects inhaled 2 mg of methacholine, whereas subjects with asthma inhaled the dose of methacholine causing a 15% fall in FEV(1), as determined by a previous methacholine challenge. LES motility, esophageal pH, and FEV(1) were not significantly different between the three periods in healthy subjects. In patients with asthma, methacholine induced a 21.9 +/- 2.6% decrease in FEV(1) and a concomitant increase in the rate of transient LES relaxation (TLESR) and reflux episodes. Inhalation of salbutamol decreased the rate of TLESRs but not the number of reflux episodes. We conclude that in patients with asthma, methacholine-induced bronchospasm increases the rate of TLESR and the number of reflux episodes. These results support the belief that, in asthma, bronchial obstruction may be responsible for reflux or may aggravate reflux through a mechanism that remains to be further clarified.

Reduction of the internal atrial defibrillation threshold with balanced orthogonal sequential shocks

INTRODUCTION

The aim of this study was to determine the atrial defibrillation threshold (ADFT) of a first shock across the standard right atrium (RA) to distal coronary sinus (dCS) configuration followed by a second shock along the atrial septum with a standard sequential waveform (the second shock leading edge equaled the first shock trailing edge) and a balanced sequential waveform (the leading edges of both shocks were equal).

METHODS AND RESULTS

In nine sheep atrial fibrillation was induced with acetyl-beta-methylcholine and burst pacing. A catheter was placed with electrodes in the dCS, proximal coronary sinus (pCS), and RA. A J-shaped catheter was positioned with an electrode at Bachmann's bundle (BB) while another catheter was positioned with an electrode in the superior vena cava (SVC). The ADFTs of six single- and dual-pathway configurations were determined with single, standard sequential, or balanced sequential shocks. The ADFT of the RA-->dCS configuration (0.86 +/- 0.27 J, 159 +/- 29 V, 2.42 +/- 0.36 A) was significantly reduced when followed by an SVC-->pCS (0.58 +/- 0.17 J, 112 +/- 20 V, 1.64 +/- 0.39 A) or a BB-->pCS shock (0.64 +/- 0.16 J, 119 +/- 18 V, 1.81 +/- 0.38 A) with standard sequential shocks. With balanced sequential shocks, the peak voltage and current ADFTs were further significantly reduced (85 +/- 11 V and 1.24 +/- 0.21 A for second shock SVC-->pCS, and 93 +/- 13 V and 1.38 +/- 0.27 A for second shock BB-->pCS).

CONCLUSION

The ADFT of the standard RA-->dCS shock is significantly reduced when followed by a second shock along the atrial septum delivered between electrodes in the pCS and either SVC or BB and ADFT is further reduced with balanced sequential shocks.

Adenosine-mediated bronchoconstriction and lung inflammation in an allergic mouse model

In this study, we studied the role of adenosine on airway responsiveness and airway inflammation using an allergic mouse model. Mice were sensitized by two i.p. injections of ragweed and three consecutive ragweed aerosol challenges. It was found that inhalation of adenosine causes a dose-related bronchoconstriction in this model. Ragweed sensitized and challenged mice showed increased sensitivity to airway challenge to adenosine compared to control animals. Theophylline, a non-selective adenosine receptor antagonist, blocked adenosine-induced bronchoconstriction, but was unable to inhibit bronchoconstrictor response to methacholine. Mice systemically sensitized and airway challenged with allergen showed a marked airway inflammation manifesting increases in eosinophils, lymphocytes and neutrophils, and decrease in macrophages. Twenty-four hours after airway challenge with allergen, aerosolization of adenosine further potentiated the allergen-induced airway inflammation. Cells in bronchoalveolar lavage fluid after adenosine aerosolization increased by 3.07-fold as compared to control mice, and by 1.8-fold compared to ragweed sensitized and challenged mice. The increases in eosinophils, lymphocytes, and neutrophils caused by allergen were potentiated after adenosine challenge. Unexpectedly, macrophages significantly decreased after adenosine challenge. Theophylline attenuated adenosine-enhanced airway inflammation, but could not reverse allergen-induced airway inflammation. These findings suggested that specific adenosine receptors contribute to airway responsiveness and airway inflammation associated with this model of allergic asthma.

Bronchial responsiveness to eucapnic hyperventilation and methacholine following exposure to organic dust

STUDY OBJECTIVE

Inhalation of dust in a swine confinement building causes an intense airway inflammatory reaction in the airways and increased bronchial responsiveness to methacholine. The aims of the present study were to investigate whether exposure to organic dust also influences bronchial responsiveness to an indirect stimulus, and to assess the duration of increased postexposure bronchial responsiveness.

DESIGN

Twenty-two healthy nonatopic, nonsmoking subjects were exposed to dust for 3 h in a swine confinement building. Lung function was assessed, and either a methacholine bronchial provocation (n = 11) or a challenge with eucapnic hyperventilation of dry air (n = 11) was performed before exposure and at 7 h, 1 week, 2 weeks, and 4 weeks after exposure.

RESULTS

Vital capacity and FEV(1) decreased 3% and 6%, respectively (p < 0.001), and airway resistance increased 15% (p < 0.05) after exposure. The median provocative dose of methacholine causing a 20% decline in FEV(1) fell from 1.38 mg (25th to 75th percentiles, 0.75 to 7.20 mg) before exposure to 0.18 mg (0.11 to 0.30 mg) after exposure (p = 0.004). Corresponding values for the dose-response slope were 15.3%/mg (2.88 to 25.3%/mg) and 100.2%/mg (2.1 to 27.3%/mg), respectively (p = 0.01). Bronchial responsiveness to eucapnic hyperventilation was not affected by the exposure: FEV(1) fell 4.3% (- 7.2 to - 1.8%) before and 4.8% (- 6.7 to - 1.6%) after exposure (p = 0.72). One week after exposure, the bronchial responsiveness to methacholine was normalized.

CONCLUSIONS

The bronchial responsiveness to methacholine but not to dry air increases after exposure to swine house dust. Thus, exposure to organic dust induces increased bronchial responsiveness with different characteristics from that frequently found in asthma.

Sensitivity to methacholine and capsaicin in patients with unclear respiratory symptoms

BACKGROUND

Capsaicin, the pungent ingredient in red pepper, is known to stimulate coughing via the sensory nervous system. Earlier studies showed that patients with airway symptoms induced by chemicals and strong scents cough more after inhalation of capsaicin than healthy control subjects and this has been interpreted as a hyperreactivity of airway sensory nerves. Our aim was to study airway sensitivity to inhaled capsaicin and the occurrence of airway symptoms induced by strong scents in patients who underwent a bronchial methacholine test, primarily because of suspected asthma.

METHODS

Fifty-two consecutive patients referred for testing with methacholine were also provoked with inhaled capsaicin in increasing concentrations. Cough sensitivity to capsaicin was compared with that in 40 healthy control subjects.

RESULTS

The patients coughed significantly more compared with the healthy control subjects with each dose of capsaicin (P < 0.0001). Twelve patients (23%) had a positive methacholine test, and of these, nine were diagnosed with asthma. There was no difference in capsaicin sensitivity between patients sensitive or insensitive to methacholine.

CONCLUSIONS

The majority of the patients had no increased sensitivity to methacholine but did demonstrate sensory hyperreactivity (SHR). SHR appears to be a common diagnosis in investigations of patients with obscure airway symptoms.

Induction and recovery phases of methacholine-induced bronchoconstriction using FEV1 according to the degree of bronchial hyperresponsiveness

Forty-eight patients suffering from intermittent bronchial asthma underwent methacholine challenge test. Response was stronger in 29 patients and less pronounced in 19. The two groups had the same characteristics except for the cumulative methacholine dose which was lower in severe hyperresponsiveness. The patients were studied both in the phase of induced bronchospasm and in the subsequent phase of spontaneous recovery. Dose-response curves to methacholine were analyzed as FEV1% decline/methacholine dose for the induction phase of bronchoconstriction and as FEV1% increase*methacholine dose/time after PD20FEV1 for the recovery phase. The phase of induced bronchospasm as well as spontaneous recovery had a linear pattern in severe hyperresponsiveness; in patients with moderate response, induced bronchoconstriction had a curvilinear pattern whereas spontaneous recovery had a linear pattern. This latter group had to break down an amount of methacholine that was fivefold greater than the former, therefore the mechanism of local homeostasis recovery may be more efficient in moderate hyperresponsiveness. However, in both groups recovery after the bronchospasm was not complete after 60 min (p < 0.01 versus baseline). Furthermore, recovery was faster in the first 15 min than in the remaining time. In conclusion the behavior of methacholine-induced bronchospasm and its spontaneous recovery in both severe and moderate hyperresponsiveness seem to be different although several and not well-established mechanisms may be responsible for this phenomenon.

Comparison of the anti-bronchoconstrictor activities of inhaled formoterol, its (R,R)- and (S,S)-enantiomers and salmeterol in the rhesus monkey

The principle objective of this study was to define the anti-bronchoconstrictor effects of inhaled racemic formoterol and its (R,R)- and (S,S)-enantiomers in a new model of methacholine-induced bronchoconstriction in the rhesus monkey. A second long-acting beta(2)agonist, salmeterol, was included for comparison. Anaesthetized, spontaneously breathing rhesus monkeys were set up for measuring airway resistance. Blood pressure, heart rate and serum potassium concentrations were measured concomitantly to gauge systemic exposure and the potential for side effects. Formoterol, 0.14, 0.34 and 1.15 microg/kg, administered by aerosol, induced rapidly developing, sustained, dose-related inhibition of the bronchoconstrictor responses to aerosolised methacholine (maximum 76%) accompanied by sustained, dose-related tachycardia. (R,R)-formoterol, 0.56 microg/kg, induced anti-bronconstrictor effects and an associated tachycardia which corresponded closely to the effects seen following twice the dose of the racemate. (S,S)-formoterol, 0.54 microg/kg, was inactive. Salmeterol, 1.4 microg/kg, had no significant anti-bronchoconstrictor effect whereas doses of 5.5 and 30 microg/kg produced quantitatively similar but submaximal anti-bronchoconstrictor effects (maximum 47%). Sustained dose-dependent tachycardia was seen with salmeterol over the full dose range. Thus, the anti-bronchoconstrictor activity of formoterol resides in the (R,R) enantiomer and the (S,S) enantiomer does not interfere with the activity when present in the racemic form. Furthermore, the data indicate that the present model of methacholine-induced bronchospasm in the rhesus monkey could be useful in defining the key properties of beta(2)agonist bronchodilators such as relative potency, efficacy, duration of action and potential for systemic side effects.

Dose-dependent effects of inhaled mometasone furoate on airway function and inflammation after allergen inhalation challenge

Comparisons of the potency of different inhaled corticosteroids, delivery devices, and treatment regimens in the management of asthma can only be made when outcome measurements display a dose-dependent effect. These outcomes have been difficult to identify. In this study, we compared in a randomized, double-blind, crossover design, the effects of 6 d treatment with placebo and three doses (50, 100, and 400 microg, twice daily) of mometasone furoate delivered by dry powder inhaler (MF-DPI) on responses after allergen inhalation challenge. Twelve mild asthmatic subjects with dual responses after allergen inhalation were studied. Outcome measurements included early and late asthmatic responses, the change in methacholine airway responsiveness 24 h after challenge, and sputum eosinophilia measured 7 and 24 h after challenge. All three doses of MF-DPI demonstrated similar attenuation of early responses and allergen-induced airway hyperresponsiveness relative to placebo (p < 0.05). The late maximal %fall in FEV(1) after placebo treatment was 23.5% and was significantly reduced in a dose-dependent manner to 12.3%, 11.0%, and 5.9% for the 50-, 100-, and 400-microg twice-daily treatments (p = 0.007). The allergen-induced increase in sputum eosinophilia (x10(4) cells/ml) 24 h after challenge during placebo treatment was 60.2 and was significantly reduced to 24.0, 15.3, and 6.2 for the 50-, 100-, and 400-microg twice-daily treatments. MF-DPI is effective at attenuating allergen-induced early and late responses, airway hyperresponsiveness, and sputum eosinophilia, and dose-response effects exist for the attenuation of the late response.

Decreased bronchodilating effect of salbutamol in relieving methacholine induced moderate to severe bronchoconstriction during high dose treatment with long acting beta2 agonists

BACKGROUND

In vitro the long acting beta2 agonist salmeterol can, in contrast to formoterol, behave as a partial agonist and become a partial antagonist to other beta2 agonists. To study this in vivo, the bronchodilating effect of salbutamol was measured during methacholine induced moderate to severe bronchoconstriction in patients receiving maintenance treatment with high dose long acting beta2 agonists.

METHODS

A randomised double blind crossover study was performed in 19 asthmatic patients with mean forced expiratory volume in one second (FEV1) of 88.4% predicted and median concentration of methacholine provoking a fall in FEV1 of 20% or more (PC(20)) of 0.62 mg/ml at entry. One hour after the last dose of 2 weeks of treatment with formoterol (24 microg twice daily by Turbuhaler), salmeterol (100 microg twice daily by Diskhaler), or placebo a methacholine provocation test was performed and continued until there was at least a 30% decrease in FEV1. Salbutamol (50 microg) was administered immediately thereafter, followed by ipratropium bromide (40 microg) after a further 30 minutes. Lung function was monitored for 1 hour after provocation.

RESULTS

There was a significant bronchodilating and bronchoprotective effect after 2 weeks of active treatment. The dose of methacholine needed to provoke a fall in FEV1 of > or = 30% was higher after pretreatment with formoterol (2.48 mg) than with salmeterol (1.58 mg) or placebo (0.74 mg). The difference between formoterol and salmeterol was statistically significant: 0.7 doubling dose steps (95% CI 0.1 to 1.2, p=0.016). The immediate bronchodilating effect of subsequently administered salbutamol was significantly impaired after pretreatment with both drugs (p<0.0003 for both). Three minutes after inhaling salbutamol the increase in FEV1 relative to the pre-methacholine baseline was 15.8%, 7.3%, and 5.5% for placebo, formoterol and salmeterol, respectively (equivalent to increases of 26%, 14%, and 12%, respectively, from the lowest FEV1 after methacholine). At 30 minutes significant differences remained, but 1 hour after completing the methacholine challenge FEV1 had returned to baseline values in all three treatment groups.

CONCLUSION

Formoterol has a greater intrinsic activity than salmeterol as a bronchoprotective agent, indicating that salmeterol is a partial agonist compared with formoterol in contracted human airways in vivo. Irrespective of this, prior long term treatment with both long acting beta2 agonists reduced the bronchodilating effect of an additional single dose of salbutamol equally, indicating that the development of tolerance or high receptor occupancy overshadowed any possible partial antagonistic activity of salmeterol. Patients on regular treatment with long acting beta2 agonists should be made aware that an additional single dose of a short acting beta2 agonist may become less effective.

Intradermal tests with vasomotor agents in perennial non-allergic rhinitis

Nasal reactivity in non-allergic rhinitis patients is well known, but the skin reactivity of these patients is less examined. The aim of this prospective study was to examine the skin reactivity to four vasomotor agents in healthy subjects and perennial non-allergic rhinitis patients and to determine whether rhinitis patients differ from healthy subjects or not. Seventy four perennial non-allergic rhinitis patients and fourty two healthy subjects were undergone to intradermal testing with papaverine (5 mg/ml), metacholine (0.02, 0.2 and 2.0 mg/ml), histamine (0.01, 0.1 and 10.0 micrograms/ml) and compound 48/80 (0.01, 0.1, 1.0 and 10.0 micrograms/ml). It was found that the frequency of pathological skin reactivity to papaverine in perennial non-allergic rhinitis patients (34%) was significantly greater (p = 0.007) then in healthy subjects (9.5%). There was no significant difference for metacholine, histamine, compound 48/80 and saline between these two groups. The frequency of the total pathological skin reactivity to vasomotor agents, singly and in combinations, in perennial non-allergic rhinitis patients (80%) was significantly greater (p = 1.8.10(-6)) then in healthy subjects (33%). These findings suggest that the pathological skin reactivity to vasomotor agents is a feature of perennial non-allergic rhinitis patients as well as healthy subjects and indicate that a difference in the skin reactivity between these groups is noticed.

Ventilatory support by tracheal gas insufflation and chest vibration during bronchoconstriction

OBJECTIVE

To determine whether chest wall vibration with tracheal gas insufflation during bronchoconstriction maintains gas exchange at lower airway and intrathoracic pressures than those that occur during positive pressure ventilation.

DESIGN

Prospective study.

SETTING

Experimental laboratory.

SUBJECTS

Six anesthetized, paralyzed mongrel dogs (mean weight, 24.7+/-3.8 kg).

INTERVENTIONS

Dogs were ventilated by two methods: mechanical ventilation (7 breaths/min, 25 mL/kg tidal volume); and tracheal oxygen insufflation at 0.15 L x kg(-1) x min(-1) delivered with external chest wall vibration (29 Hz, 2 mm amplitude) of the dependent hemithorax. Bronchoconstriction was induced by methacholine infusion adjusted to double and quadruple the baseline airway resistance. Proximal mean airway pressure was kept equal for both modes of ventilation.

MEASUREMENTS AND MAIN RESULTS

Airway pressure and flow, esophageal pressure, hemodynamic variables (cardiac output, systemic and pulmonary arterial pressures, pulmonary artery occlusion pressure) and gas exchange variables (PaO2, PaCO2, pH, shunt fraction, VO2) were measured. Peak airway pressure was lower (p < .05) with insufflation and vibration than with mechanical ventilation by 83.6% at baseline resistance, by 76.9% at twice baseline resistance, and by 76.8% at four times baseline resistance. Peak esophageal pressure was lower (p < .05) during insufflation with vibration by 68.5% at baseline resistance, by 87.5% at twice baseline resistance, and by 107% at four times baseline resistance. During insufflation with vibration, mild hypercapnia (PaCO2 58+/-3 torr (7.7+/-0.4 kPa) and pH 7.28+/-0.02) developed with moderate bronchoconstriction; more profound respiratory acidosis (PaCO2 137+/-41 torr (18.2+/-5.5 kPa) and pH 6.87+/-0.11) developed with severe bronchoconstriction.

CONCLUSIONS

Tracheal gas insufflation with chest vibration supports gas exchange with permissive hypercapnia only during moderate, not severe, bronchoconstriction. Gas exchange was achieved at lower airway and intrathoracic pressures than those that developed during mechanical ventilation. The alveolar hypoventilation that occurred during insufflation with vibration indicates impaired CO2 elimination and suggests increased resistance to CO2 transport. This ventilation technique may confer therapeutic advantages over mechanical ventilation in the treatment of asthma.

[Randomized double-blind study (third place blinded) to examine the effectiveness and side effects of methacholine in the nonspecific bronchial provocation test]

Softly and effectiveness of methacholine for the diagnosis of non-specific bronchial hyperresponsiveness [BHR] were tested in a third place blinded study. 61 patients suspected to suffer from BHR took part. 56 subjects provided complete data and were included in the study. 27 participants were challenged with methacholine 0.33% (verum) and 29 patients received NaCl 0.9% (placebo). The challenge was applied as 5-step-test using a storage bag. The doses were elevated by doubling the aerosol volume. A positive test result was assumed when basal specific airway resistance (sRt) reduplicated and simultaneously 2.0 (kPa*s) was attained. Ten out of 27 subjects in the verum group (33.3%) had a positive test result whereas in the placebo group only one subject showed a reaction (3.5%). A statistically significant association between the change of sRt and the cumulative methacholine dose was confirmed in the verum group (p < 0.002), whereas this effect could not be observed in patients challenged with placebo (p = 0.20). Side effects did not occur. We conclude that inhalative challenge with methacholine 0.33% applied as a 5-step-test is suitable to objectify BHR. The substantial benefit of the applied test scheme is the short range of time in which the challenge can be performed (approximately 20 min) and that dilution series of the test substance (methacholine 0.33%) are not required.

The pharmacology of aerosolized airway challenge

Clinicians who perform and interpret airway challenge tests must understand the pharmacology involved. This knowledge helps one appreciate the need for certain procedures and the importance of proper technique. Methacholine and histamine are the most commonly used airway challenge agents. The authors review the pharmacology of methacholine and histamine airway challenge testing and discuss issues regarding the performance and interpretation of an airway challenge test.

Bronchoprotective and bronchodilator effects of single doses of (S)-salbutamol, (R)-salbutamol and racemic salbutamol in patients with bronchial asthma

OBJECTIVES

The drug salbutamol is used as a 50: 50 racemic mixture of its two enantiomers, (R)- and (S)-salbutamol. Previous studies suggest that the (R)-enantiomer is active, and the (S)-enantiomer is either inert or may be responsible for adverse effects. The aim of the study was to measure the protection given against methacholine (MCh) and adenosine monophosphate (AMP) by (R)-, (S)- and rac-salbutamol and their bronchodilator effects.

METHODS

A double-blind, placebo-controlled, four-way cross-over study was performed in subjects with mild to moderate asthma. There were three groups: AMP30 (n = 10), MCh30 (n = 13) and MCh180 (n = 10). The groups received AMP or MCh challenges at either 30 min or 180 min after each of four pretreatments: 100 microg (S)-salbutamol, 100 microg (R)-salbutamol, 200 microg rac-salbutamol or placebo (normal saline), each administered via nebuliser. Spirometry was measured at 30, 60, 90, 120, 150 and 180 min in the MCh180 group.

RESULTS

(R)- and rac-salbutamol showed equivalent bronchoprotective effects at 30 min. PC20AMP increased by 3.22 (1.86) and 3.41 (2.15) doubling doses (P < 0.001) and PC20MCh increased by 2.86 (1.09) and 2.75 (0.89) (P < 0.001) respectively. (S)-salbutamol caused no equivalent effect. There was no significant effect at 180 min. No hyper-responsiveness occurred after treatment with (S)-salbutamol. The mean increase in forced expiratory volume in 1 s (FEV1) was 12.4% (6.8%) with (R)- and 12.0%(7.7%) with rac-salbutamol at 90 min. No significant change in FEV1 occurred with (S)-salbutamol.

CONCLUSIONS

These results confirm other recent findings that the bronchoprotective and bronchodilator effects of salbutamol are attributable to its (R)-enantiomer. No adverse effects were noted after single doses of (S)-salbutamol.

Fluticasone propionate and bronchial hyperresponsiveness in childhood asthma

Bronchial asthma is now agreed as being a chronic inflammatory disease of the airways. Inhaled steroids are widely accepted as a preventive medication in asthmatic patients of all ages and severity. However, the optimal use of inhaled steroids and the important issue of safety and efficacy still remain of concern, particularly in children. Recently, fluticasone propionate (FP) has been developed for use as an inhaled preparation for the treatment of asthma. Because of its high topical potency and increased lipophilicity, it is claimed that FP has an improved risk/benefit compared with other inhaled steroids. In order to evaluate the use of FP in children, we have studied the efficacy of high dose FP (500 microg/day) in asthmatic children. Thirteen children (9 boys and 4 girls), aged 7-17 years (10.8 +/- 2.6), were instructed to use a pressurized metered-dose inhaler connected to a Volumetric spacer. The standard methacholine bronchial challenge test was used as a principal outcome parameter. The PD20, a cumulative dose of methacholine inducing a 20% decrease in FEV1, was measured pre- and post-treatment with inhaled FP. After 4 weeks of FP, PD20 significantly increased from 21.6 +/- 14.3 inhalation unit to 106.6 +/- 78.5 inhalation unit (4.9 fold, p = 0.004) reflecting the improvement of airway reactivity. All subjects improved clinically. These results demonstrate that the anti-inflammatory action of FP 500 microg a day for four weeks can markedly reduce bronchial hyperresponsiveness, the basic physiologic abnormality in bronchial asthma.

Protective effects of different doses of inhaled fenoterol on methacholine-induced bronchoconstriction in asthmatic children

OBJECTIVE

To evaluate the protective effect of different doses of inhaled fenoterol (F) on bronchoconstriction induced by methacholine (M).

DESIGN

Randomized double-blind study.

SETTING

Referrence center.

PARTICIPANTS

9 children (aged from 7 to 15 years old), with mild or moderate asthma and allergic to D. pteronyssinus.

INTERVENTION

On the first day, the M concentration necessary to induce a 20% fall in the forced expiratory volume in the first second (FEV1; PC20FEV1) was determined using closed circuit inhalation (De Vilbiss 646). On subsequent days, the children inhaled a dose of F (25 or 50 or 100 or 200 micrograms) through the same circuit and, after 15 minutes the FEV1 was measured, becoming the basal value. Bronchoprovocation was then initiated using the concentration prior to the PC20FEV1 of the first day and continuing until there was a 20% fall in the FEV1. This concentration was the "new" PC20FEV1.

RESULTS

F in a dose of 25 micrograms protected 2 of the 9 children, in a dose of 50 mg protected 4 of the 9 and in doses of 100 and 200 micrograms protected all children. We did not observe any relationship between the magnitude of the bronchodilation and bronchoprotection induced by the inhalation of F.

CONCLUSIONS

Our results suggest that a dose of 100 micrograms of F is capable of inducing bronchoprotection in children with mild/moderate asthma.