One week treatment with salmeterol does not prevent early and late asthmatic responses and sputum eosinophilia induced by allergen challenge in asthmatics

Can β2-adrenoceptor agonists, anticholinergic drugs, and theophylline contribute to the control of pulmonary inflammation and emphysema in COPD?

Chronic obstructive pulmonary disease (COPD) has become a global epidemic disease with an increased morbidity and mortality in the world. Inflammatory process progresses and contributes to irreversible airflow limitation. However, there is no available therapy to better control the inflammatory progression and therefore to reduce the exacerbations and mortality. Thus, the development of efficient anti-inflammatory therapies is a priority for patients with COPD. β(2) -Adrenoceptor agonists and anticholinergic agents are widely used as first line drugs in management of COPD because of their efficient bronchodilator properties. At present, many studies in vitro and some data obtained in laboratory animals reveal the potential anti-inflammatory effects of these bronchodilators but their protective role against chronic inflammation and the development of emphysema in patients with COPD remains to be investigated. The anti-inflammatory effects of theophylline at low doses have also been identified. Beneficial interactions between glucocorticoids and bronchodilators have been reported, and signaling pathways explaining these synergistic effects begin to be understood, especially for theophylline. Recent data demonstrating interactions between anticholinergics with β(2) -adrenoceptor agonists aiming to better control the pulmonary inflammation and the development of emphysema in animal models of COPD justify the priority to investigate the interactive effects of a tritherapy associating corticoids with the two main categories of bronchodilators.

Allergen-induced airway inflammation and its therapeutic intervention

Allergen inhalation challenge has been useful for examining the mechanisms of allergen-induced airway inflammation and the associated physiological changes and for documenting the efficacy of drugs to treat asthma. Allergen inhalation by a sensitized subject results in acute bronchoconstriction, beginning within 15-30 min and lasting 1-3 hr, which can be followed by the development of a late asthmatic response. Individuals who develop both an early and late response after allergen have more marked increases in airway hyperresponsiveness, and greater increases in allergen-induced airway inflammation, particularly in airway eosinophils and basophils. All of the currently available and effective treatments for asthma modify some aspects of allergen-induced responses. These medications include short-acting and long-acting inhaled β₂-agonists, inhaled corticosteroids, cromones, methylxanthines, leukotriene inhibitors, and anti-IgE monoclonal antibody. In addition, allergen inhalation challenge has become a useful method which can, in a very limited number of patients, provide key information on the therapeutic potential of new drugs being developed to treat asthma.

The allergen bronchoprovocation model: an important tool for the investigation of new asthma anti-inflammatory therapies

Allergen bronchoprovocation tests have been used for more than two decades in the investigation of respiratory allergic diseases such as asthma and rhinitis. These bronchial challenges are now well standardized and can offer key information on the therapeutic potential of new agents and on their anti-inflammatory effects on the airways. Both standard and low-dose allergen provocations are safe when performed by experienced investigators and do not lead to persistent worsening of asthma or change in airway function. The evaluation of new therapeutic agents by these methods can also provide important information on the mechanisms of development and persistence of airway diseases.

Sputum induction in children with asthma: a tertiary-center experience

Our aims were 1) to report on our experience with sputum induction (SI), and 2) to determine predictive factors associated with successful SI in asthmatic children. Children with asthma attending the chest clinic of a university teaching hospital between October 2003-December 2004 were recruited. They completed a visual analogue scale for symptom severity, and underwent physical examination, skin-prick test, exhaled nitric oxide (eNO) measurement, spirometry, and SI. Adequate sputum contained <50% squamous epithelial cells. Predictors for successful induction were evaluated using multivariate logistic regression analysis. One hundred and thirty subjects were recruited. The median age was 11.25 years (range 7.0-17.5), and the majority were boys (75%). All except two had normal percent predicted forced expired volume in 1 sec (>80%). The median eNO was 48.95 ppb. Sputum induction was successful in 93 subjects (74.5%). Sore throat and chest discomfort occurred in 20 (15%) and 8 (6%) subjects, respectively, and the procedure was prematurely terminated in three cases. Levels of eNO were found to be a predictor for successful induction (area under the ROC (receiver operator characteristics curves) curve, 0.634). Sputum induction was well-tolerated by all subjects, and was successful in 74.5% of cases. Exhaled nitric oxide may be a useful marker for successful induction.

Beta-adrenoceptor responses of the airways: for better or worse?

Beta2-adrenoceptor agonists are the first-line treatment of asthma and chronic obstructive pulmonary disease (COPD), in which a short-acting beta2-adrenoceptor agonist is used as required for relief of bronchoconstriction. A long-acting beta2-adrenoceptor agonist may be added to an inhaled corticosteroid as step 3 in the management of chronic asthma. Long-acting beta2-adrenoceptor agonists may also be added in treatment of COPD. This review examines the beneficial and detrimental effects of beta2-adrenoceptor agonists. The beneficial effects of beta2-adrenoceptor agonists are mainly derived from their bronchodilator activity which relieves the bronchiolar narrowing and improves air flow. The potential anti-inflammatory actions of stabilizing mast cell degranulation and release of inflammatory and bronchoconstrictor mediators, is considered. Other potential beneficial responses include improvements in mucociliary clearance and inhibition of extravasation of plasma proteins that is involved in oedema formation in asthma. The side effects of beta2-adrenoceptor agonists are primarily related to beta2-adrenoceptor-mediated responses at sites outside the airways. Of major concern has been the development of tolerance and this is discussed in relation to incidence of increased morbidity and mortality to asthma over the past three decades. A clinical aspect of beta2-adrenoceptor pharmacology in recent years has been the recognition of genetic polymorphism of the receptor and how this affects responses to and tolerance to beta2-adrenoceptor agonists. A controversial feature of beta2-adrenoceptor agonists is their stereoisomerism and whether the inactive (S)-isomer of salbutamol had detrimental actions in the commercially used racemate. The consensus is that despite these adverse properties, beta2-adrenoceptor agonist remains the most useful pharmacological agents in the management of asthma and COPD.