Abstract
BackgroundIt has been reported that Chlamydophila (C.) pneumoniae is involved in the initiation and promotion of asthma and chronic obstructive pulmonary diseases (COPD). Surprisingly, the effect of C. pneumoniae on airway function has never been investigated.MethodsIn this study, mice were inoculated intranasally with C. pneumoniae (strain AR39) on day 0 and experiments were performed on day 2, 7, 14 and 21.ResultsWe found that from day 7, C. pneumoniae infection causes both a sustained airway hyperresponsiveness and an inflammation. Interferon-γ (IFN-γ) and macrophage inflammatory chemokine-2 (MIP-2) levels in bronchoalveolar lavage (BAL)-fluid were increased on all experimental days with exception of day 7 where MIP-2 concentrations dropped to control levels. In contrast, tumor necrosis factor-α (TNF-α) levels were only increased on day 7. From day 7 to 21 epithelial damage and secretory cell hypertrophy was observed. It is suggested that, the inflammatory cells/mediators, the epithelial damage and secretory cell hypertrophy contribute to initiation of airway hyperresponsiveness.ConclusionOur study demonstrates for the first time that C. pneumoniae infection can modify bronchial responsiveness. This has clinical implications, since additional changes in airway responsiveness and inflammation-status induced by this bacterium may worsen and/or provoke breathlessness in asthma and COPD.
Highlights
The association between respiratory infections and asthma exacerbations has been evaluated both for viral agents [1,2,3], and non-viral respiratory pathogens, such as Mycoplasma pneumoniae and Chlamydophila pneumoniae [48]
C. pneumoniae infection may be a cofactor in the pathogenesis of airway diseases such as asthma and chronic obstructive pulmonary diseases (COPD) [11,32,33,34]
It has been suggested that acute infection with C. pneumoniae is associated with new onset of asthma [4,10], and C. pneumoniae and M. pneumoniae infections are involved in acute exacerbations of asthma
Summary
The association between respiratory infections and asthma exacerbations has been evaluated both for viral agents [1,2,3], and non-viral respiratory pathogens, such as Mycoplasma pneumoniae and Chlamydophila pneumoniae [48]. Involvement of C. pneumoniae in the initiation and promotion of asthma and COPD has been suggested [912]. C. pneumoniae can be isolated from tissues and peripheral blood mononuclear cells, and specific DNA can be detected in the same sites by PCR [20] and by immunohistochemistry [17,21]. The effect of this bacterium on airway responsiveness has not yet been investigated. It has been reported that Chlamydophila (C.) pneumoniae is involved in the initiation and promotion of asthma and chronic obstructive pulmonary diseases (COPD). The effect of C. pneumoniae on airway function has never been investigated
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