What are the pathological changes in asthma?

The pathologic changes include hyperplasia of mucous glands, hyperemia and edema of the mucosa, eosinophilic infiltration of the mucosa, hypertrophy of bronchiolar mus- culature, and formation of mucous plugs.

How Does asthma affect lung structure?

During an asthma attack the muscle wall contracts and the lining of the airways becomes swollen and inflamed. These changes cause a narrowing of the airways which is further aggravated by an increase in secretions from the mucus membrane, which may actually block the smaller airways.

What is hyperplasia of bronchial walls?

Mucous gland hyperplasia (as seen in the images below) is the histologic hallmark of chronic bronchitis. Airway structural changes include atrophy, focal squamous metaplasia, ciliary abnormalities, variable amounts of airway smooth muscle hyperplasia, inflammation, and bronchial wall thickening.

What is vascular congestion in asthma?

The airway wall of patients with asthma is characterized by increased smooth muscle mass, mucous gland hypertrophy and vascular congestion leading to a thickened airway wall and markedly reduced airway calibre 18–23. These features may contribute to the development of airflow limitation by increasing airway resistance.

How are airway changes related to the development of asthma?

This working definition and its recognition of key features of asthma have been derived from studying how airway changes in asthma relate to the various factors associated with the development of airway inflammation (e.g., allergens, respiratory viruses, and some occupational exposures) and recognition of genetic regulation of these processes.

How is asthma characterized by the respiratory lamina propria?

Asthma is characterized by characteristic morphological changes to the airway wall from the trachea to the terminal bronchioles, although pathology is the most intense in the bronchi. The respiratory lamina propria displays a characteristic chronic inflammatory infiltrate which includes eosinophils, macrophages, mast cells, and T-cells.

Why does asthma cause increase in smooth muscle mass?

The increase in smooth muscle mass may be due to several factors, including proliferation of smooth muscle induced by inflammatory mediators 26, cytokines 27 and growth factors 28, 29. It has been suggested that an intrinsic abnormality of smooth muscle may underlie asthma severity, but data are lacking to support this hypothesis.

What are the most characteristic inflammatory findings in asthma?

The respiratory lamina propria displays a characteristic chronic inflammatory infiltrate which includes eosinophils, macrophages, mast cells, and T-cells. The most characteristic inflammatory findings in asthma are the eosinophilic infiltrate and the T-cells which are skewed to the Th2 subtype of CD4+ T-cells and appear to secrete IL-4 and IL-5.