Bronchitis pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D. [2]; Nate Michalak, B.A.

Bronchitis Main page
Patient Information
Overview
Causes
Classification Acute bronchitis Chronic bronchitis
Differential Diagnosis

Overview

Bronchitis is the inflammatory response of the bronchial epithelium to infections or irritants. The pathophysiological findings seen with acute bronchitis include: wall thickening, inflammation, and increased mucus production. When the process becomes chronic, bronchial mucociliary function decreases, leading to airway clogging by debris and copious mucus secretion.

Pathophysiology

Pathogenesis

• Acute bronchitis:

Inflammatory response of the bronchial epithelium to infectious agents or irritants that involve the medium and large size airways results in thickening of the bronchial and tracheal mucosa.

• Chronic bronchitis:

Hallmark features include: hyperplasia and hypertrophy of the goblet cells of the airway, resulting in an increase in secretion of mucus, which contributes to airway obstruction.

Microscopy

• Acute bronchitis caused by influenza virus shows an epithelial-cell desquamation in association with the presence of a lymphocytic cellular infiltrate.
• On microscopic histopathological analysis, chronic bronchitis shows infiltration of the airway walls with inflammatory cells, particularly CD8+ T-lymphocytes and neutrophils. Inflammation is followed by scarring and remodeling that thickens the walls resulting in narrowing of the small airways. Further progression leads to metaplasia and fibrosis of the lower airway. The consequence of these changes is a limitation of airflow.