The immediate and short-term effects of corticosteroids on cholinergic hyperreactivity and pulmonary function in subjects with well-controlled asthma

Prednisolone hastens recovery from histamine-induced bronchospasm in asthmatics

Short-term treatment with oral steroids is very effective in control ling symptoms and improving lung function in asthma but has not been shown unequivocally to reduce bronchial hyperresponsiveness. Recently it has been shown to increase the activities of sodium-potassium and calcium adenosine triphosphatases, enzymes that regulate intracellular calcium levels. This action may be expected to promote recovery of cells from an excitatory stimulus. The present study was carried out to determine how prednisolone modulates airway response to histamine, including recovery from induced bronchospasm in asthmatics. Spirometry and measurement of bronchial responsiveness (forced expiratory volume in 1 sec [FEV1] and concentration of histamine causing a 20% reduction FEV1 [PD20 FEV1]) to inhaled histamine were carried out in 10 clinically stable asthmatics. Subsequently, all of the patients were prescribed oral prednisolone, 0.6-0.75 mg/kg body weight for 1 week. At the end of 1 week, spirometry was repeated and bronchial reactivity was measured again. Comparison of PD20 FEV1 values before and after treatment (geometric means 0.66 and 0.81 mg/mL, respectively) for the whole group did not show any significant change. The mean +/- SD time for 95% recovery from histamine-induced bronchospasm was 33.00 +/- 19.47 min before treatment and decreased significantly to 18.00 +/- 7.88 min after treatment. It was concluded that short-term benefits from oral prednisolone do not result from changes in bronchial responsiveness. These benefits may be related to effects on mechanisms that lead to recovery from an excitatory stimulus.

Early effects of inhaled steroids on airway hyperreactivity and pulmonary function in asthma

While inhaled steroids (IS) are increasingly recognized as having a more rapid onset of action than was once thought, little is known about the early changes in objective measures of respiratory function that follow the inhalation of repeated doses. These early effects were examined in a randomized, double-blind, placebo-controlled, crossover study of 20 children aged 10-16 years with stable mild asthma. Beclomethasone dipropionate (BDP) 2,000 mcg, fluticasone propionate (FP) 400 mcg, and placebo were given twice daily for three doses. Airway hyperreactivity (AHR) to methacholine (PC20), pulmonary function tests (PFT: FVC, FEV1, FEF25-75%), and the rate of recovery from methacholine-induced bronchospasm following administration of salbutamol were determined at 8 h (after 1 dose) and at 32 h (after three doses). At 8 h, minor improvements in AHR were demonstrated, averaging 0.32 doubling doses in PC20. At 32 h, significant improvements in AHR and PFTs were present, averaging 0.92 doubling doses in PC20, 3.96% of predicted values in FEV1, and 7.74% of predicted values in FEF25-75%. No significant changes occurred in FVC. There were no significant differences between the effects of BDP and FP. Inhaled steroids were associated with a slower response to salbutamol following methacholine challenge testing at 32 h. We conclude that IS, given in repeated high doses, result in significant improvements within 32 h in both AHR and PFTs, along with changes in response to beta2 agonists. These effects are likely to be the result of the topical activity of IS.

The role of corticosteroids in respiratory diseases of children

Glucocorticosteroids are potent anti-inflammatory agents and have an important role in a variety of respiratory diseases. Although their exact mode of action is unknown, it is thought that they exert their effects by binding to cytoplasmic glucocorticoid receptors. In certain conditions, such as asthma, the value of steroids cannot be questioned, and inhaled steroids have revolutionized management. In other situations, such as interstitial lung disease, the true role of steroids is still to be defined. In the management of diseases such as tuberculosis, the use of steroids is solely based on anecdotal experience.

Constitutive expression of endothelin in bronchial epithelial cells of patients with symptomatic and asymptomatic asthma and modulation by histamine and interleukin-1

BACKGROUND

An upregulation of endothelin-1 expression occurs in bronchial epithelial cells of asthmatic patients. This peptide may mediate bronchoconstriction in asthma, but the mechanisms that modulate endothelin-I synthesis and release are unknown.

OBJECTIVE

This study was done to compare the pattern of endothelin-1 expression in patients with symptomatic and asymptomatic asthma and evaluate the ability of inflammatory factors to upregulate endothelin-1 synthesis and release in the epithelial cells of subjects who are free of symptoms.

METHODS

Two groups of 10 asthmatic patients were selected. One group had symptomatic asthma with airflow obstruction and moderately to severely increased airway responsiveness. The second group was free of symptoms: they did not show airflow obstruction, and airway responsiveness was borderline or slightly increased. Bronchial biopsy specimens were obtained by means of bronchoscopy and used for immunohistochemical evaluation, epithelial cell isolation, and stimulation experiments with interleukin-1 and histamine.

RESULTS

Endothelin-1 immunoreactivity was detected in vivo in the bronchial epithelial cells of all the patients with symptoms and in only two subjects without current symptoms. Incubation of bronchial epithelial cells from patients with asymptomatic asthma with interleukin-1 or histamine, for 8 to 24 hours, resulted in increased expression of endothelin-1 messenger RNA and release of appreciable amounts of the peptide to the culture medium. Those effects were dose- and time-dependent. Histamine and interleukin-1 were effective at concentrations similar to those detected in the bronchoalveolar lavage of patients with symptomatic asthma.

CONCLUSION

Endothelin-expression is upregulated in bronchial epithelial cells of asthmatic patients with symptoms and evidence of functional derangement as compared with patients without symptoms and airflow obstruction. Exposure of cells from patients with asymptomatic asthma to factors that are released during acute exacerbation of the disease induces endothelin synthesis and release.

Detection of cytokines and their cell sources in bronchial biopsy specimens from asthmatic patients. Relationship to atopic status, symptoms, and level of airway hyperresponsiveness

This study evaluated immunoreactivity for several cytokines in bronchial tissue of asthmatic patients and related this to the clinical and functional characteristics. Patients were allocated into two different groups on the basis of their atopic status (atopic and nonatopic), with two subgroups of symptomatic and asymptomatic subjects in each. Five healthy volunteers were tested as control subjects. After clinical and functional assessment, all of the subjects underwent bronchoscopy. Several biopsy specimens were obtained for immunohistochemical and immunoelectron microscopic evaluation. Symptomatic asthmatic subjects had increased expression of immunoreactive interleukin (IL) 1 beta, IL-2, IL-3, IL-5, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor alpha (TNF alpha) when compared to the asymptomatic patients or normal control subjects. The cell sources of IL-1 beta were monocytes and dendritic cells in atopic patients and monocytes alone in nonatopic asthmatic subjects. The CD4+ T lymphocytes from atopic asthmatic subjects predominantly expressed IL-3, IL-4, IL-5, and GM-CSF immunoreactivity, whereas CD4+ T cells from nonatopic patients predominantly expressed IL-2, IL-3, and IL-5, and GM-CSF immunoreactivity. Mast cells showed immunoreactivity for TNF alpha, IL-3, IL-5, and GM-CSF. Immunostaining for TNF alpha and GM-CSF was also detected in bronchial epithelial cells and monocytes. Tissue eosinophilia and the level of airway hyperresponsiveness more closely correlated with IL-5 immunoreactivity in atopic asthmatic subjects and with IL-2 and GM-CSF immunoreactivity in nonatopic patients.

Bronchoconstrictive responses to inhaled ultrasonically nebulized distilled water and airway inflammation in asthma

Twenty-two asthmatic patients with a range of airway hyperresponsiveness to methacholine underwent a bronchial challenge with ultrasonically nebulized distilled water (UNDW). The presence of positive responses to this stimulus was related to the extent of airway inflammation, as assessed by histochemical and immunohistochemical evaluation of bronchial biopsy specimens. Twelve patients had airflow obstruction during distilled water inhalation and they showed more severe disease than subjects with no response, as demonstrated by the higher degree of nonspecific bronchial hyperresponsiveness (p < 0.01), higher variability of peak expiratory flow rates (p < 0.01), symptom scores (p < 0.01), and daily use of bronchodilators (p < 0.01). Those patients also had increased numbers of mast cells and eosinophils (p < 0.01) and increased percentage of bronchial epithelial cells expressing endothelin 1 immunoreactivity (p < 0.01). Thus, positive responses to inhaled UNDW reflect the bronchial hyperresponsiveness consistent with moderate to severe asthma and may be due to the release of mediators with bronchoconstrictive properties from inflammatory cells or activated resident cells or both.

Intraepithelial dendritic cells and selective activation of Th2-like lymphocytes in patients with atopic asthma

This study examines the distribution of intraepithelial dendritic cells in eight atopic patients with symptomatic asthma and their ability to induce activation of autologous T lymphocytes in vitro. All subjects were sensitized to Dermatophagoides pteronyssinus. The incubation of asthmatic epithelial cells and dendritic cells with autologous resting CD4-positive T cells and purified extracts of D pteronyssinus induced T cell activation and release of high levels of interleukin-4 (IL-4) and interleukin-5 (IL-5). The antigen-presenting activity of dendritic cells was potentiated by epithelial cell-derived granulocyte-macrophage colony-stimulating factor (GM-CSF), since an antibody against GM-CSF reduced it. Circulating monocytes of the two groups of donors were equally effective in promoting selective activation of IL-4- and IL-5-producing T cells. Thus, an interaction between dendritic cells and allergens may favor local activation of CD4-positive T cells with Th2-like function in atopic asthmatic subjects, thereby promoting the expression of the disease.

Cytokine mRNA profile and cell activation in bronchoalveolar lavage fluid from nonatopic patients with symptomatic asthma

Recent studies have indicated that airway inflammation in atopic asthma is characterized by T-cell activation and local eosinophilia, but it is unknown whether this also applies to nonatopic asthma. In this study, the cytokine mRNA profile and activation status of inflammatory cells in bronchoalveolar lavage fluid (BALF) of eight nonallergic patients with symptomatic asthma and eight nonallergic healthy controls were compared using the message amplification phenotyping (MAPPing) with the polymerase chain reaction (PCR) procedure and immunocytochemical evaluation. Asthmatics had an increasing number of inflammatory cells in BALF, including activated eosinophils (EG2-positive) (p less than 0.001) and activated T cells (CD25-positive) (p less than 0.001). Activated T cells from five of the eight asthmatic patients and from one control subject expressed high levels of interleukin 5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF). All the asthmatic patients had increased numbers of monocytes in their BALF (p less than 0.002) and those cells invariably showed increased expression of interleukin 1 beta (IL1 beta) transcripts. In five patients they also expressed appreciable levels of IL-6 and GM-CSF mRNA. IL-5 and GM-CSF can induce local activation of eosinophils, and IL-1 beta and IL-6 are known to promote T-cell activation and proliferation. Thus, there is an increased production of cytokines with inflammatory properties in the airways of patients with nonatopic symptomatic asthma, which may contribute to the persistence of inflammation, and monocytes and activated T cells are important sources of these cytokines.

The effect of 2 weeks treatment with cetirizine on bronchial reactivity to methacholine in asthma

1. We investigated the effect of 2 weeks therapy with oral cetirizine (10 mg twice daily) on methacholine bronchial reactivity in 14 asthmatics. All had bronchial hyperreactivity to methacholine on entry to the study, with a geometric mean cumulative PC20 of 0.83 mg ml-1 (range 0.1-3.61 mg ml-1) and eight were atopic on skin prick testing. 2. The study was placebo-controlled and in randomised order, with a minimum 1 month washout period between cetirizine and placebo study periods. Four methacholine challenges were performed in all, at the beginning and at the end of each study period. 3. No significant change in methacholine reactivity was found following 2 weeks therapy with cetrizine. The repeatability coefficient for the PC20 methacholine over 2 weeks was found to be 2.90 doubling dilutions for the placebo period and 1.73 doubling dilutions for the cetirizine period. The study had a 80% power at the 5% significance level (two-tailed) to detect a 1.16-doubling concentration change in methacholine reactivity. 4. We conclude that 2 weeks therapy with cetirizine has no significant effect on non-specific bronchial hyperreactivity.

Effect of prednisone and beclomethasone dipropionate on airway responsiveness in asthma: a comparative study

To examine the effect of corticosteroids on bronchial hyperresponsiveness, a randomised, double dummy, single blind crossover study was performed in 18 subjects with chronic asthma, comparing the effect of three weeks' treatment with inhaled beclomethasone dipropionate, 1200 micrograms daily, and oral prednisone 12.5 mg daily. The 12 week study began with a three week run in period of baseline treatment, which was continued unchanged throughout the study, and the two treatment periods were separated by a three week washout period. Patients kept daily Airflometer readings and attended the laboratory every three weeks for spirometry and a histamine inhalation test for determining the provocative dose of histamine causing a 20% fall in FEV1 (PD20). The mean FEV1 at the start was 1.9 litres (56% predicted). There was no significant change in PD20 with prednisone treatment, the mean PD20 being 0.56 and 0.59 mumol before and after treatment. There was, however, a significant improvement in PD20 with beclomethasone dipropionate treatment, the geometric mean PD20 being 0.38 and 1.01 mumol before and after treatment (p less than 0.001). There was a small but significant improvement in mean FEV1 after beclomethasone dipropionate treatment--from 1.9 to 2.2 litres--but no change after prednisone. Both medications produced significant and similar improvements in morning and evening Airflometer readings, post-bronchodilator improvement, and diurnal variation. Thus at doses that had similar beneficial effects on lung function beclomethasone dipropionate caused a significant improvement in bronchial hyperresponsiveness whereas prednisone caused no change. The superior topical anti-inflammatory effect of beclomethasone dipropionate may account for the different effects on bronchial hyperresponsiveness.

Comparison of bronchial responses to ultrasonically nebulized distilled water, exercise, and methacholine in asthma

We compared the responses to inhaled methacholine, ultrasonically nebulized distilled water, and exercise in 25 subjects with atopic asthma. The methacholine inhalation test and challenges with distilled water and exercise were performed on three separate days 48 hours apart. Bronchial responsiveness to methacholine and ultrasonically nebulized distilled water was measured as the concentration of methacholine (PC20M) and the volume output of the ultrasonic nebulizer (PO20 UNDW) producing a 20 percent fall in the forced expiratory volume in one second (FEV1). The response to exercise was expressed as the percentage of fall in FEV1 from the value before exercise. Seventeen subjects showed a fall in FEV1 of more than 20 percent after exercise. Eight subjects had a stimulus-response curve to distilled water that was flat up to the maximal volume output from the nebulizer, but only four of them also showed no significant response to exercise. The response to exercise correlated better with PO20 UNDW (r = -0.66; p less than 0.01) than with PC20M (r = -0.19; p greater than 0.5) in those responding to distilled water. In all of the tested subjects, exercise-induced bronchoconstriction correlated with PC20M (r = -0.61; p less than 0.01). The mean PC20M was significantly lower in the subjects with a significant response to distilled water and exercise (p less than 0.001 and p less than 0.0001, respectively). We concluded that ultrasonically nebulized distilled water and exercise provoke significant bronchoconstriction in the subjects with more severe nonspecific bronchial hyperresponsiveness. The correlation found between the two stimuli supports the hypothesis that they act by similar mechanisms.

Increase in bronchial responsiveness to methacholine and late asthmatic response after the inhalation of ultrasonically nebulized distilled water

We studied ten subjects who had an asthmatic response after the inhalation of ultrasonically nebulized distilled water and did not show any refractory period to repeated challenge with such water. The change in responsiveness to methacholine after inhalation of distilled water and the occurrence of any water-induced late asthmatic response were investigated on separate days. All of the tested subjects showed a significant increase in bronchial responsiveness to methacholine after prior stimulation with ultrasonically nebulized distilled water, which waned within two hours in eight of them. The other two subjects showed a progressive increase in responsiveness to methacholine, and they also had a further reduction in the caliber of the airways three to four hours after inhalation of distilled water. The late responses were less severe than the initial responses and lasted four to five hours. After the spontaneous recovery, no significant increase in responsiveness to methacholine was detected. Our results confirm previous observations on hyperresponsiveness induced by ultrasonically nebulized distilled water and demonstrate the occurrence of late reactions after inhalation of such water.