Biomedical Engineering Reference
In-Depth Information
Table 3
Characteristics of Inflammation in COPD and Asthma
COPD
Asthma
Cells
Neutrophils
Eosinophils
Large increase in
macrophages
Small increase in macrophages
Increase in CD8
þ
T-lymphocytes
Increase in CD8
þ
T-lymphocytes
Increase in CD4
þ
Th2 lymphocytes
Activation of mast cells
Mediators
LTB4
LTD4
IL-8
IL-4, IL-5
TNF-
a
(Plus many others)
Consequences
Squamous metaplasia
of epithelium
Fragile epithelium
Parenchymal destruction
Thickening of basement membrane
Mucus metaplasma
Mucus metaplasia
Glandular enlargement
Glandular enlargement
Response to
treatment
Glucorticoids have little
or no effect
Glucorticoids inhibit inflammation
Source: adapted from Ref. 2.
airway fluid, a metaplasia of airway epithelium with hyperplasia of goblet
cells. In addition, peripheral airways show increased intraluminal mucus
and exudate, increased mass of smooth muscle, airway wall fibrosis, distor-
tion, and obliteration, loss of alveolar attachments to the bronchiolar walls.
In the lung parenchyma, the characteristics pathological abnormalities are
the presence of (a) panlobular emphysema (PLE) and centrilobular emphy-
sema (CLE) in various combination; (b) paraseptal emphysema; and (c) loss
of vascular bed linked to emphysema.
Up to 20% of clearly defined COPD patients have a significant rever-
sibility of airflow limitation to bronchodilators and
=
or glucocorticosteroids
(9,35,36). These patients have the same pathologic abnormalities of COPD
patients, but also some pathological features of asthma, namely a small but
significant increase of eosinophils in bronchoalveolar-lavage (BAL) fluid,
and a slight but significant increase of the thickness of the reticular layer
of the basement membrane (9). Moreover, in COPD with partial reversi-
bility of airflow limitation, the bronchodilator response is associated with
increased exhaled NO and sputum eosinophilia (37).
B. Asthma
In asthma, most studies have included mild asthma, and have concentrated
on biopsies from central airways. These studies have consistently shown that
