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Immunopathogenesis of polymicrobial otitis media
1The Research Institute at Nationwide Children's Hospital, Center for Microbial Pathogenesis, The Ohio State University College of Medicine, Columbus, OH 43205-2696, USA. lauren.bakaletz@nationwidechildrens.org
Abstract:
OM, or inflammation of the middle ear, is a highly prevalent infection in children worldwide. OM is a multifactorial disease with multiple risk factors, including preceding or concurrent viral URT infection. Hence, OM is also a polymicrobial disease. The mechanisms by which viruses predispose to bacterial OM are replete; however, all are predicated on the general principle of compromise of primary host airway defenses. Thus, despite an as-yet incomplete understanding of the molecular mechanisms involved in bacterial superinfection of a virus-compromised respiratory tract, the URT viruses are known to induce histopathology of airway mucosal epithelium, up-regulate expression of eukaryotic receptors used for bacterial adherence, alter the biochemical and rheological properties of airway mucus, and affect innate and acquired host immune functions, among others. Although discussed here in the context of OM, during preceding or concurrent viral infection of the human respiratory tract, viral impairment of airway defenses and the resulting predisposition to subsequent bacterial coinfection are also known to be operational in the mid and lower airway as well.
Insights
Viral respiratory infections weaken children's natural airway defenses, increasing their risk for secondary bacterial infections like otitis media (OM). Understanding these viral mechanisms is key to preventing OM.
Area of Science:
- Microbiology
- Immunology
- Pediatrics
Background:
- Otitis media (OM), or middle ear inflammation, is a common childhood infection.
- Viral upper respiratory tract (URT) infections are significant risk factors for developing OM.
- OM is recognized as a polymicrobial disease, often involving secondary bacterial infections.
Purpose of the Study:
- To elucidate the mechanisms by which viral URT infections predispose children to bacterial OM.
- To highlight the impact of viral infections on host airway defenses.
- To provide a comprehensive overview of viral-bacterial interactions in respiratory infections.
Main Methods:
- Review of existing literature on viral URT infections and their link to bacterial OM.
- Analysis of the molecular and cellular changes induced by viruses in the respiratory tract.
- Examination of the impact on host immune functions and airway properties.
Main Results:
- Viral URT infections compromise primary host airway defenses.
- Viruses induce histopathological changes in airway mucosal epithelium.
- Viruses alter mucus properties and affect both innate and acquired immune functions, facilitating bacterial adherence and superinfection.
- These mechanisms are relevant to OM and other respiratory tract infections.
Conclusions:
- Viral infections significantly impair airway defenses, creating a vulnerability for bacterial superinfections like OM.
- Understanding these viral mechanisms is crucial for developing strategies to prevent secondary bacterial infections in children.
- The findings have implications for respiratory health beyond otitis media, affecting mid and lower airway infections as well.
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