Abstract
BackgroundChlamydia pneumoniae and Mycoplasma pneumoniae have been implicated in the pathogenesis of asthma and are responsible for chronic inflammation when host immune system fails to eradicate the bacteria.MethodWe performed a prospective study on 410 patients who underwent a visit at the asthma clinic of CHU of Liege between June 2016 and June 2018 with serology testing for C. pneumoniae and M. pneumoniae.Results65% of our asthmatic population had serum IgA and/or IgG towards C. pneumoniae, while only 12.6% had IgM and/or IgG against M. pneumoniae. Compared to seronegative asthmatics, asthmatics with IgA+ and IgG+ against C. pneumoniae were more often male and older with a higher proportion of patients with smoking history. They received higher doses of inhaled corticosteroids (ICS) and displayed lower FEV1/FVC ratio, higher RV/TLC ratio and lower conductance. They had higher levels of fibrinogen, though in the normal range and had lower sputum eosinophil counts. Patients with IgA− and IgG+ against C. pneumoniae were older and had higher blood monocyte counts and alpha-1-antitrypsin levels as compared to seronegative patients. Patients with IgM and/or IgG towards M. pneumoniae were more often males than seronegative asthmatics. In a subpopulation of 14 neutrophilic asthmatics with Chlamydia pneumoniae IgA + /IgG + treated with macrolides, we found a significant decrease in blood neutrophils and normalization of sputum neutrophil count but no effect on asthma quality of life and exacerbations.ConclusionPositive Chlamydia serologic test is more common than positive Mycoplasma serology. Asthmatics with IgA and IgG against C. pneumoniae have more severe disease with increased airway obstruction, higher doses of ICS, more signs of air trapping and less type-2 inflammation.
Highlights
Asthma is an inflammatory disease of the airways that is characterized by airway hyperresponsiveness towards various environmental factors
406 asthmatics who underwent a visit to the asthma clinic in stable state with a measurement of serum Immunoglobin A (IgA) and Immunoglobin G (IgG) for Chlamydia pneumoniae and IgG and Immunoglobin M (IgM) for Mycoplasma pneumoniae were included in this study
We found a positive correlation between the level of IgG against Chlamydia pneumoniae and age (p = 0.0058, r = 0.14), history of smoking measured in pack-years (p = 0.0043, r = 0.14), air trapping (residual volume on total lung capacity ratio (p = 0.04, r = 0.11)) and alpha-1 antitrypsin level (p = 0.0087, r = 0.14) while there was a negative correlation with FEV1/Forced vital capacity (FVC) ratio (p = 0.0199, r = − 12), post-BD Forced expiratory volume in one second (FEV1) (p = 0.04, r = − 0.10) and Specific airway conductance (sGaw) (p = 0.04, r = − 0.11)
Summary
Asthma is an inflammatory disease of the airways that is characterized by airway hyperresponsiveness towards various environmental factors. Chlamydia pneumoniae seems to be able to impair apoptosis of infected cells leading to chronic infection and to induce ciliostasis in the bronchi. Mycoplasma pneumoniae attaches to and destroys ciliated epithelial cells of the respiratory tract mucosa. It induces the secretion of IL-8 and TNF-alpha in vitro [16], Type-2 allergic inflammation in sensitized mice [17] and increased serum IL-4, IL-5 [18] and IgE levels in vivo [19]. Chlamydia pneumoniae and Mycoplasma pneumoniae have been implicated in the pathogenesis of asthma and are responsible for chronic inflammation when host immune system fails to eradicate the bacteria
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