Infection-mediated asthma: etiology, mechanisms and treatment options, with focus on Chlamydia pneumoniae and macrolides

Abstract

Asthma is a chronic respiratory disease characterized by reversible airway obstruction and airway hyperresponsiveness to non-specific bronchoconstriction agonists as the primary underlying pathophysiology. The worldwide incidence of asthma has increased dramatically in the last 40 years. According to World Health Organization (WHO) estimates, over 300 million children and adults worldwide currently suffer from this incurable disease and 255,000 die from the disease each year. It is now well accepted that asthma is a heterogeneous syndrome and many clinical subtypes have been described. Viral infections such as respiratory syncytial virus (RSV) and human rhinovirus (hRV) have been implicated in asthma exacerbation in children because of their ability to cause severe airway inflammation and wheezing. Infections with atypical bacteria also appear to play a role in the induction and exacerbation of asthma in both children and adults. Recent studies confirm the existence of an infectious asthma etiology mediated by Chlamydia pneumoniae (CP) and possibly by other viral, bacterial and fungal microbes. It is also likely that early-life infections with microbes such as CP could lead to alterations in the lung microbiome that significantly affect asthma risk and treatment outcomes. These infectious microbes may exacerbate the symptoms of established chronic asthma and may even contribute to the initial development of the clinical onset of the disease. It is now becoming more widely accepted that patterns of airway inflammation differ based on the trigger responsible for asthma initiation and exacerbation. Therefore, a better understanding of asthma subtypes is now being explored more aggressively, not only to decipher pathophysiologic mechanisms but also to select treatment and guide prognoses. This review will explore infection-mediated asthma with special emphasis on the protean manifestations of CP lung infection, clinical characteristics of infection-mediated asthma, mechanisms involved and antibiotic treatment outcomes.

Tracheal microbial populations in horses with moderate asthma

“…are also found in children with asthma . Chlamydophila spp., another atypical bacteria associated with asthma exacerbation in humans, were detected by immunohistochemistry more frequently in the bronchial epithelial cells of asthmatic horses . It is also important to realize that several bacteria such as Chamydophila spp.…”

Vitamin A supplement after neonatal Streptococcus pneumoniae pneumonia inhibits the progression of experimental asthma by altering CD4+T cell subsets

“…It is now well accepted that asthma is a heterogeneous disease with different clinical subtypes. Viral infections have been implicated in asthma pathogenesis as well as exacerbation [22][23][24][25] . Atypical pathogen infection (such as Mycoplasma pneumoniae) also appears to play an important role in the induction and exacerbation of asthma both in children Whole-body plethysmography in mock-infected, non-allergic (Control), mock-infected, allergic (OVA), neonatal infected, allergic (S.pp/OVA) and vitamin A supplement after neonatal infected, allergic (S.pp+VA/ OVA) mice was conducted 24 h following challenge with methacholine (n = 6-8 mice/group).…”

Special Considerations in Preschool Age

“…Infections with Chlamydia pneumoniae and Mycoplasma pneumoniae early in life have been confirmed to predispose for wheezing and asthma. An infectious etiology behind asthma mediated by C. pneumoniae has been confirmed [123]. C. pneumoniae has been detected in bronchoalveolar lavage (BAL) fluid in children aged 0-20 years with asthma [124] along with M. pneumoniae more often in children aged 2-14 years who wheeze compared to healthy controls [14,125].…”