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Community-Acquired Pneumonia Microchapters |
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Differentiating Community-acquired pneumonia from other Diseases |
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Diagnosis |
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Directions to Hospitals Treating Community-acquired pneumonia |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]
Pathophysiology
Diminished Mucociliary Clearance
The cilia lining the respiratory epithelium serve to move secreted mucus containing trapped foreign particles including pathogens towards the oropharynx for either expectoration or swallowing. Elevated incidence of pneumonia in patients with genetic defects affecting mucociliary clearance such as primary ciliary dyskinesia suggests its role in the pathogenesis of community-acquired pneumonia.
Impaired Cough Reflex
Cough, together with mucociliary clearance, prevent pathogens from entering the lower respiratory tract. Cough suppression or cough reflex inhibition seen in patients with cerebrovascular accidents and drug overdosages is associated with an enhanced risk for aspiration pneumonia. Another relation to cough is genetic polymorphisms in the angiotensin-converting enzyme (ACE) gene. The role of cough in preventing pneumonia may be explained by a higher risk for developing pneumonia in homozygotes carrying deletion/deletion (DD) genotype who are found to have lower levels of bradykinin and tachykinins such as substance P.[1][2]
Defective Immnue System
Pathogen-associated molecular patterns (PAMPs) are initially recognized by Toll-like receptors (TLRs) and other pattern-recognition receptors (PRRs) of the innate immune system. Effectors in the acquired immune system are involved in elimination of microorganisms and generation of immunological memory. Other components in the immune system such as complement system, cytokines, and collectins, also mediate the defense against microorganisms causing pneumonia.
References
- ↑ Morimoto, S.; Okaishi, K.; Onishi, M.; Katsuya, T.; Yang, J.; Okuro, M.; Sakurai, S.; Onishi, T.; Ogihara, T. (2002). "Deletion allele of the angiotensin-converting enzyme gene as a risk factor for pneumonia in elderly patients". Am J Med. 112 (2): 89–94. PMID 11835945. Unknown parameter
|month=ignored (help) - ↑ Rigat, B.; Hubert, C.; Alhenc-Gelas, F.; Cambien, F.; Corvol, P.; Soubrier, F. (1990). "An insertion/deletion polymorphism in the angiotensin I-converting enzyme gene accounting for half the variance of serum enzyme levels". J Clin Invest. 86 (4): 1343–6. doi:10.1172/JCI114844. PMID 1976655. Unknown parameter
|month=ignored (help)