Neutral endopeptidase (NEP, EC3. 4. 24. 11) and angiotensin-converting enzyme (ACE, EC3. 4. 15. 1) have an important role in the regulation of inflammation by cleaving peptides which cause such states. On the other hand, aminopeptidase (AP) may be critical to the generation of bradykinin (BK) in allergic response. We studied the activity and release of nasal mucosa NEP, ACE, and AP in order to improve control of upper-airway neurogenic inflammation.
In the membrane-rich fraction of allergic nasal mucosa, NEP was more abundant than ACE or AP. In the cytosolic fraction, however, AP was more abundant than NEP or ACE. All three enzymes increased their activity in nasal secretion withinn 30 minutes after antigen challenge. AP activity in nasal secretion after antigen challenge was 10 times higher than NEP or ACE activity. These result indicate that NEP have more effect of cleaving neuroptptide than ACE, and also indicate that AP make BK upregulation against the cleavage by ACE. The existence of NEP, ACE, and AP in the nasal mucosa and nasal lavage fluid suggest that these enzymes have some role in the control of neurogenic inflammation in allergic rhinitis.