Shelley E. Overbeek

Mucosal and systemic inflammatory changes in allergic rhinitis and asthma: a comparison between upper and lower airways

Background Local airway inflammation and airway remodelling are considered important in the clinical expression of allergic asthma.

A Cystic Fibrosis Mutation Associated with Mild Lung Disease

BACKGROUND Cystic fibrosis is the most common lethal autosomal recessive disorder among whites. Among Dutch patients with cystic fibrosis, delta F508 is the most common mutation and A455E the second most common mutation of the cystic fibrosis transmembrane conductance regulator gene on chromosome 7. A455E is associated with preserved pancreatic function and residual secretion of chloride across membranes. We investigated whether it is also associated with less severe pulmonary disease in patients with cystic fibrosis. METHODS A total of 33 patients with compound heterozygosity for the A455E mutation were matched according to age and sex with patients who were homozygous for the delta F508 mutation. The pairs were analyzed with respect to the following outcome variables: age at diagnosis, pulmonary-function values, and the frequency of pseudomonas colonization, pancreatic sufficiency, and diabetes mellitus. RESULTS Cystic fibrosis was diagnosed at a later age in the patients with the A455E mutation than in the delta F508 homozygotes (mean age at diagnosis, 15.0 vs. 3.1 years; P < 0.001). Fewer patients with the A455E mutation had pancreatic insufficiency (21.2 percent vs. 93.9 percent, P < 0.001), and none had diabetes mellitus (0 percent vs. 27.3 percent, P = 0.004). Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were significantly higher in the patients with the A455E mutation (mean FEV1, 73.9 percent of the predicted value vs. 54.3 percent of the predicted value; P = 0.002; mean FVC, 88.7 percent of the predicted value vs. 76.3 percent of the predicted value; P = 0.04). Fewer patients with the A455E mutation were colonized with Pseudomonas aeruginosa (33.3 percent vs. 60.6 percent, P = 0.02). CONCLUSIONS A455E is a common mutation causing cystic fibrosis in the Netherlands. Although several mutations are known to be associated with less severe pancreatic disease, our findings demonstrate a correlation between the A455E mutation and mild pulmonary disease. Because mortality in this disease depends primarily on the progression of pulmonary disease, patients with the A455E mutation have a better prognosis than patients who are homozygous for the delta F508 mutation.

Peak flow variation in childhood asthma: relationship to symptoms, atopy, airways obstruction and hyperresponsiveness

Although home recording of peak expiratory flow (PEF) is considered useful in managing asthma, little is known about the relationship of PEF variation to other indicators of disease activity. We examined the relationship of PEF variation, expressed in various ways, to symptoms, atopy, level of lung function, and airways hyperresponsiveness in schoolchildren with asthma. One hundred and two asthmatic children (aged 7-14 yrs) recorded symptoms and PEF (twice daily) in a diary for 2 weeks after withdrawal of all anti-inflammatory maintenance medication. PEF variation was expressed as amplitude % mean, as standard deviation and coefficient of variation of all recordings, and as low % best (lowest PEF as percentage of the highest of all values). Atopy and level of forced expiratory volume in one second (FEV1) % predicted were not significantly related to PEF variation. The provocative dose of histamine causing a 20% fall in FEV1 (PD20) and symptom scores were significantly, but weakly, related to PEF variation. The index, low % best, proved easy to calculate and effective in identifying a short-term episode of reduced PEF. We conclude that peak expiratory flow variation in children with stable, moderately severe asthma is significantly, but weakly, related to symptoms and airways hyperresponsiveness. These three phenomena, therefore, all provide different information on the actual disease state. Expressing peak expiratory flow variation as low % best is easy to perform and appears to be clinically relevant.

Effects of fluticasone propionate on methacholine dose-response curves in nonsmoking atopic asthmatics

Methacholine is frequently used to determine bronchial hyperresponsiveness (BHR) and to generate dose-response curves. These curves are characterized by a threshold (provocative concentration of methacholine producing a 20% fall in forced expiratory volume in one second (PC20) = sensitivity), slope (reactivity) and maximal response (plateau). We investigated the efficacy of 12 weeks of treatment with 1,000 microg fluticasone propionate in a double-blind, placebo-controlled study in 33 atopic asthmatics. The outcome measures used were the influence on BHR and the different indices of the methacholine dose-response (MDR) curve. After 2 weeks run-in, baseline lung function data were obtained and a MDR curve was measured with doubling concentrations of the methacholine from 0.03 to 256 mg x mL(-1). MDR curves were repeated after 6 and 12 weeks. A recently developed, sigmoid cumulative Gaussian distribution function was fitted to the data. Although sensitivity was obtained by linear interpolation of two successive log2 concentrations, reactivity, plateau and the effective concentration at 50% of the plateau value (EC50) were obtained as best fit parameters. In the fluticasone group, significant changes occurred after 6 weeks with respect to means of PC20 (an increase of 3.4 doubling doses), plateau value fall in forced expiratory volume in one second (FEV1) (from 58% at randomization to 41% at 6 weeks) and baseline FEV1 (from 3.46 to 3.75 L) in contrast to the placebo group. Stabilization occurred after 12 weeks. Changes for reactivity were less marked, whereas changes in log, EC50 were not significantly different between the groups. We conclude that fluticasone is very effective in decreasing the maximal airway narrowing response and in increasing PC20. However, it is likely that part of this increase is related to the decrease of the plateau of maximal response.

Effect of montelukast compared with inhaled fluticasone on airway inflammation

Background Inhaled corticosteroids are currently regarded as the gold standard in anti‐inflammatory therapy, however, leukotriene receptor antagonists have been ascribed anti‐inflammatory properties.

Cystic fibrosis, pathophysiological and clinical aspects

Cystic fibrosis is a lethal, hereditary, until recently little understood disease, which leads to progressive functional disturbances in various organs, including the lungs, liver and pancreas. Knowledge of the genetic and cellular abnormalities is rapidly progressing, but therapy is still symptomatic and based on insufficiently controlled and short-term studies. At present the therapeutic approach aims to combat respiratory infections by optimal antibiotic therapy, combined with techniques to promote sputum evacuation. Additional measures attempt to optimise both nutritional state and physical condition. Median survival has imporved from approximately 1 year to about 25 years during the past 3 decades. This article summarises present information on disease mechanisms and treatment.

Dyspnoea perception during clinical remission of atopic asthma

Symptoms of atopic asthma often disappear around puberty. The authors recently demonstrated that this clinical remission is accompanied with ongoing airways inflammation in most subjects. The discrepancy between lack of symptoms and persistent airway inflammation suggests that perception of the symptoms is unclear. In the present study, young adults in clinical remission of atopic asthma assigned themselves a modified Borg score during methacholine and adenosine-5′-monophosphate induced bronchoconstriction. Borg scores of subjects in clinical remission were compared with those of symptomatic asthmatic subjects. A marked variation in the Borg scores at a 20% fall in the forced expiratory volume in one second was found. Significant differences in Borg scores between remission patients and asthmatics could not be detected. It was concluded that perception of dyspnoea, induced with methacholine and adenosine challenge, is similar in young adults in clinical remission of atopic asthma compared to that of patients with symptomatic asthma. Hence, an unclear perception seems to be an unlikely explanation for the discrepancy between lack of symptoms and ongoing inflammation. Other factors, including both physical and psychological ones, may play a role in the apparent absence of symptoms, thereby potentially leading to undertreatment.

Lower leukotriene C-4 levels in bronchoalveolar lavage fluid of asthmatic subjects after 2.5 years of inhaled corticosteroid therapy

Long-term treatment with inhaled corticosteroids has been shown to result in improvement of symptoms and lung function in subjects with asthma. Arachidonic acid (AA) metabolites are thought to play a role in the pathophysiology of asthma. It was assessed whether differences could be found in bronchoalveolar lavage (BAL) AA metabolite levels between subjects with asthma who were treated for 2.5 years with inhaled bronchodilators alone or in combination with inhaled corticosteroids. Prostaglandin (PG)D2, PGF2α, 6-keto-PGF1α, thromboxane B2, leukotriene (LT)C4 and LTB4 levels and cell numbers were assessed in BAL fluid from 22 non-smoking asthmatic subjects. They were participating in a randomized, double-blind multicentre drug trial over a period of 2.5 years. Results of the group treated with inhaled corticosteroids (CS+: beclomethasone 200 μg four times daily) were compared with the other group (CS−) which was treated with either ipratropium bromide (40 μg four times daily) or placebo. BAL LTC4 levels of asthmatic subjects were significantly lower after 2.5 years inhaled corticosteroid therapy (CS+, 9(1–17) pg/ml vs. CS−, 16(6-53) pg/ml; p = 0.01). The same trend was observed for the PGD2 levels. The results suggest that inhaled corticosteroids may exert their beneficial effect on lung function via a mechanism in which inhibition of LTC4 synthesis in the airways is involved.

Peptidases in the Asthmatic Airways

Studies on the role of peptidases in the pathogenesis of asthma have not been able to convincingly demonstrate a dysfunction of these enzymes in the airways of stable asthmatics. Although asthmatic airways are more responsive to tachykinin-induced bronchoconstriction and nasal congestion (Joos et al 1987, Joos et al 1994), no apparent reduction in NEP activity could be found in stable mild asthmatic patients (Cheung et al 1993). Our studies indicate that peptidase activities in BAL fluid and serum do not differ remarkably between healthy controls and allergic asthmatics. In addition, we did not observe major differences in the expression of APN and DPP IV between bronchial biopsies of asthmatics and healthy controls. No data are currently available on the expression of NEP in the airways of asthmatics compared to healthy subjects, although some data may suggest a reduced NEP expression in the bronchial epithelium, but not the lamina propria, from nonsteroid-treated asthmatics (Sont et al 1997). It seems therefore unlikely that there is a generally reduced activity of peptidases in the airways of stable asthmatic patients. To further determine whether peptidases and neuropeptides contribute to asthma, in vivo studies using selective neurokinin receptor antagonists should be performed both in the presence and absence of peptidase inhibitors.

Cell surface antigen expression by peripheral blood monocytes in allergic asthma: Results of 2.5 years therapy with inhaled beclomethasone dipropionate

At present, inhaled glucocorticoids are widely accepted as the therapy of choice in chronic asthma. Treatment with inhaled glucocorticoids significantly suppresses local airway inflammation in asthmatics, but may also have systemic effects, e.g. a reduction of the number of circulating hypodense eosinophils or a down-modulation of HLA-DR antigen (Ag) expression by T lymphocytes in peripheral blood. However, the effect of long-term therapy with inhaled glucocorticoids on peripheral blood monocytes (PBM), which are the precursors of the most numerous cell type in the lung, the alveolar macrophage, have not yet been evaluated. We therefore investigated the expression of various cell surface Ag on PBM from non-smoking patients with allergic asthma who were treated for 2.5 years with a beta(2)-receptor agonist plus either an inhaled glucocorticoid (beclomethasone dipropionate, BDP) (n = 4) or an anticholinergic or placebo (n = 8). We compared the results with healthy volunteers (n = 7). Long-term treatment of allergic asthmatics with inhaled BDP, but not anticholinergic or placebo therapy, was associated with a significantly lower CDllb Ag expression (p < 0.04) and higher expression of CD13, CD14 and CD18 Ag (p < 0.05, p < 0.02 and p < 0.04, respectively) when compared with the healthy control subjects (n = 7). Most interestingly, PBM of asthmatics treated with inhaled BDP expressed an almost two-fold higher level of CD14 Ag on their cell surface than PBM of patients treated with anticholinergic or placebo (p < 0.03). No significant differences in the expression of CD16, CD23, CD25, CD32 and CD64 Ag or HLA-DR were observed between PBM from the different patient groups or healthy controls. Taken together, this study shows that long-term local therapy with inhaled BDP coincides with an altered expression of at least one cell surface Ag on PBM from allergic asthmatics.