Modulation of neutrophil and inflammation markers in chronic obstructive pulmonary disease by short-term azithromycin treatment
Introduction
Macrolides are broad spectrum antibacterials, widely used in the treatment of respiratory tract infections. A large and growing body of data indicates that this class of drugs also possesses modulatory effects on innate immunity and the inflammatory response, independent of their antibacterial actions (Rubin and Tamaoki, 2000, Labro, 2000, Labro and Abdelghaffar, 2001, Čulić et al., 2001, Tamaoki, 2004). This has led to their use in the treatment of several inflammatory lung and airways diseases (Keicho and Kudoh, 2002, Beuther and Martin, 2004, Gotfried, 2004, Rubin and Henke, 2004, Schultz, 2004).
Azithromycin differs from other macrolides in that it exhibits rapid and prolonged cellular accumulation, especially within phagocytes (Zuckerman, 2000). For the treatment of bacterial infections, the localization of azithromycin in leukocytes offers the advantage of delivery of the drug to its site of action. This is also of potential benefit for treatment of inflammation. In fact azithromycin shows anti-inflammatory actions in several animal models of acute inflammation and clinical benefit when given for several months in diffuse panbronchiolitis, asthma and cystic fibrosis (Čulić et al., 2001, Beuther and Martin, 2004, Rubin and Henke, 2004, Schultz, 2004). The mechanism(s) of action of azithromycin and other macrolides in causing anti-inflammatory effects are unclear. On the basis of in vitro findings, potential mechanisms include inhibition of cytokine release, neutrophil function and mediator release, stimulation of apoptosis, as well as inhibition of mucus secretion (Čulić et al., 2001, Tamaoki, 2004). However, some unexpected stimulatory effects have also been reported.
In a previous study in healthy human volunteers, we observed that immediately after a 3-day standard dosing regimen, azithromycin caused initial stimulation of neutrophil degranulation and the oxidative burst to particulate stimuli, followed by a delayed inhibition of neutrophil function and of circulating chemokine concentrations, in association with an increase in numbers of circulating apoptotic cells and sustained levels of the drug in circulating neutrophils (Čulić et al., 2002). In order to determine whether similar actions of azithromycin can be observed in inflammatory lung disease, in which activated neutrophils play an important role, we have carried out a pilot investigation on the effect of 3-day treatment with azithromycin in patients with chronic obstructive pulmonary disease (COPD).
COPD is a major health problem worldwide and is increasing in prevalence, morbidity and mortality (Murray and Lopez, 1997). As defined by the Global Initiative for Chronic Obstructive Lung Diseases (GOLD) international consensus document (www.goldcopd.com), it is characterised by progressive development of airflow limitation that is not fully reversible. Most patients with COPD have three pathological conditions: bronchitis, emphysema and mucus plugging, with a slowly progressive and irreversible decrease in forced expiratory volume in the first second (FEV1). There is significant remodelling of airways. The inflammation associated with COPD typically includes neutrophils, macrophages, and CD8 lymphocytes (Saetta, 1999, Barnes, 2000). Neutrophils are believed to play a crucial role in the tissue damage and remodelling that occur in COPD, acting through release of reactive oxygen species and proteases (Barnes, 2000, Dhami et al., 2000, Noguera et al., 2001) The basic pathophysiology of COPD has been recognized for years and yet the only therapy shown to change the long-term course of the disease is smoking cessation. Long-acting bronchodilators may provide some symptomatic relief, and inhaled corticosteroids have been shown to decrease exacerbations and reduce healthcare utilization in specific subgroups of patients (Barnes, 2000, Hele and Belvisi, 2003). Azithromycin has been approved for treatment of acute exacerbations of COPD, but on the basis of its antibacterial, rather than its anti-inflammatory activity (Amsden et al., 2003). The aim of the present study was to measure, in a placebo-controlled pilot study, a spectrum of inflammatory variables and neutrophil functions, similar to those measured in our previous study in healthy volunteers and to determine which if any of these variables might be modulated by azithromycin in COPD, as a chronic inflammatory condition without a primary infectious aetiology.
Section snippets
Study design
The primary objective of this study was to explore the anti-inflammatory potential of azithromycin by determining its effects on selected inflammation markers in blood and sputum of COPD patients. The secondary objective was to assess the effects, if any, of short-term azithromycin administration on airway obstruction in COPD patients.
The study was designed as a double-blind, randomised, placebo-controlled, parallel group investigation. A total of 27 patients with COPD were to be included. In
Study population and demographic data
Due to a slow recruitment rate, patients were enrolled in five cohorts, and the final number of COPD patients was 24, 16 in the azithromycin group and 8 in the placebo group; 22 patients finished the study and 2 patients were withdrawn (1 due to acute respiratory infection and 1 due to acute exacerbation of COPD). Fifteen healthy volunteers were enrolled. Apart from baseline values, data from healthy controls are not presented as these were not matched with, nor intended for comparison with
Discussion
The results of this exploratory study demonstrate that, even when given for a short period of 3 days, azithromycin is able to inhibit some markers of the inflammatory response in patients with moderate COPD, in comparison to a parallel, placebo-treated group of patients. The most pronounced effects observed were a prolonged inhibition of peripheral blood leukocyte count, in association with prolonged reduction of platelet count and circulating concentrations of acute phase proteins,
Acknowledgements
We are grateful to Dr. Tatjana Glunčić-Jalušić, Hospital for Chronic Diseases, Zagreb, Dr. Marijan Merkler and Dr. Radovan Radonie, Clinical Hospital Centre, Zagreb, Dr. Dean Mileta, Diagnostic Polyclinic, Zagreb, Prof. Fadila Pavičić, University Hospital for Lung Diseases, Zagreb, Ing. Vera Robić, Centre for Clinical Drug Investigation, Zagreb, Dr. Asja Stipić-Marković, General Hospital “Sveti Duh”, Zagreb and Prof. Neven Tudorić, Clinical Hospital Dubrava, Zagreb for clinical support; Vesna
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