Biomedical Engineering Reference
In-Depth Information
Figure 5
Putative differences in airway mucus pathophysiology between COPD
and asthma. Compared with normal, in COPD there is increased luminal mucus,
goblet cell hyperplasia, submucosal gland hypertrophy (with an increased proportion
of mucous to serous acini), an increased ratio of mucin (MUC) 5B (low charge glyco-
form, lcgf) to MUC5AC, small amounts of MUC2, and respiratory infection (possi-
bly due to reduced bacterial enzymatic 'shield' from reduced serous cell number).
Pulmonary inflammation includes macrophages and neutrophils. In asthma, there
is increased luminal mucus, epithelial 'fragility', marked goblet cell hyperplasia, sub-
mucosal gland hypertrophy (although without an increased mucous to serous ratio),
'tethering' of mucus to goblet cells, and plasma exudation. Airway inflammation
includes T lymphocytes and eosinophils. Many of these differences require more data
from greater numbers of subjects.
eosinophilia) (20) underlie the differences in hypersecretory phenotype
between these two conditions.
Sputum production, up to 100mL per day in many patients, is asso-
ciated with excessive mucus in the airways (Fig. 6) (21-23). The increased
mucus is associated with goblet cell hyperplasia (21,24) and submucosal
gland hypertrophy (Fig. 7) (21,22,25,26). Of particular note is that the gland
mucous cells are markedly increased relative to the serous cells (27).
This is in contrast to asthma, where the glands, albeit hypertrophied, are
