Chlamydia pneumoniaeimmunoglobulin A reactivation and airway inflammation in acute asthma

Abstract

Infection with Chlamydia pneumoniae can trigger acute asthma and is associated with severe chronic asthma. The aim of the present study was to examine the relationship between airway inflammation and serological response to C. pneumoniae in acute severe asthma.Subjects (n=54) were recruited within 4 h of presentation to the emergency department with an acute exacerbation of asthma. Clinical history taking, sputum induction (0.9% saline), spirometry and acute and convalescent serology for C. pneumoniae immunoglobulins A and G were performed.At presentation, 47% of subjects had antibodies directed against C. pneumoniae, and 38% (20) demonstrated an increase in C. pneumoniae antibody levels, with 15 demonstrating a rise in immunoglobulin A concentration. C. pneumoniae responders exhibited significantly higher sputum neutrophil levels (4.6610 6 cells?mL -1 ) compared to nonresponders (1.2610 6 cells?mL -1 , p=0.02) and elevated sputum eosinophil cationic protein concentration (3,981 versus 1,122 ng?mL -1 , p=0.02). An acute antibody response to Chlamydia pneumoniae is common in exacerbations of asthma. The serological features suggest that Chlamydia pneumoniae reactivation may trigger neutrophilic airway inflammation in acute asthma. Eur Respir J 2002; 20: 834-840.

Azithromycin for Acute Exacerbations of Asthma

“…2 Respiratory viral infections are a frequent cause of asthma exacerbations in children 3,4 and adults. [5][6][7] Atypical bacterial (Mycoplasma pneumoniae and Chlamydophila pneumoniae) infection and/or reactivation is also associated, with serologic positivity rates of 40% to 60% in some studies, [8][9][10][11][12] indicating that viral and atypical bacterial infections may interact in increasing asthma exacerbation risk.…”

Chlamydial Respiratory Infection during Allergen Sensitization Drives Neutrophilic Allergic Airways Disease

“…Neutrophilic inflammation plays an important role during acute exacerbations of asthma, and respiratory pathogens may be implicated in these events (18,19,(35)(36)(37). More than onethird of asthmatics presenting with acute severe asthma exacerbations had elevated levels of Chlamydophila pneumoniaespecific IgG or IgA, indicating an acute or reactivated infection (19). These subjects exhibited more intense neutrophilic inflammation, compared with acute exacerbators without infection.…”

“…We have extended these studies to show that, although an active infection suppressed Th2 responses, infection should not be considered protective; rather, it changes the phenotype of AAD to one underpinned by neutrophilic inflammation that is associated with allergen-specific Th1 (IFN-g) responses. Neutrophilic inflammation plays an important role during acute exacerbations of asthma, and respiratory pathogens may be implicated in these events (18,19,(35)(36)(37). More than onethird of asthmatics presenting with acute severe asthma exacerbations had elevated levels of Chlamydophila pneumoniaespecific IgG or IgA, indicating an acute or reactivated infection (19).…”

“…Neutrophilic inflammation in asthma has been associated with viral respiratory infection (18) and correlates with increased activation of innate immune factors, namely, increased IL-8 and TLR-2 and TLR-4 expression in sputum (16). Neutrophil levels are also elevated in the sputum of exacerbating asthmatics with evidence of chlamydial respiratory infection, compared with uninfected individuals (18,19). Furthermore, chlamydial infection of mice induces a robust pulmonary neutrophil influx that is mediated by the TLR-dependent production of keratinocyte chemokine (KC) and macrophage inflammatory protein-2 (MIP-2), the mouse orthologs of human IL-8 (20,21).…”

A randomised, double-blind, placebo-controlled study to evaluate the efficacy of oral azithromycin as a supplement to standard care for adult patients with acute exacerbations of asthma (the AZALEA trial)

“…[6][7][8] However, non-viral respiratory pathogens such as Mycoplasma pneumoniae and Chlamydophila pneumoniae have also been associated with wheezing episodes and asthma exacerbations in both adults and children. [9][10][11][12][13] Interestingly, in two of these studies virus detection rates were ≈80%, 9,11 whereas serological positivity for atypical bacterial infection/reactivation can be as high as 40-60%, 9,13 indicating that viral and atypical bacterial infections probably interact in increasing the risk of asthma exacerbations.…”