Aminopeptidase activity in human nasal mucosa.
BACKGROUND
Aminopeptidases activate bradykinin and degrade many inflammatory peptides.


OBJECTIVE
The objective of this study was to identify the types of aminopeptidase activities in human nasal mucosa.


METHODS
Human nasal mucosa was homogenized (n = 12), and cytoplasmic (S2) and membrane-rich (P2) fractions were obtained. Several aminopeptidase (Ap) activities were defined by (1) substrate specificity with leucine-enkephalin (leu-Ap) and alanine-nitroanilide (ala-Ap), (2) inhibitor studies with puromycin and bestatin, (3) enzyme activity histochemistry (zymography), (4) immunohistochemistry, and (5) gel electrophoresis. Human volunteers had methacholine, histamine, and allergen nasal provocations to determine the mechanisms controlling nasal aminopeptidase secretion in vivo.


RESULTS
P2 was the largest reservoir of puromycin-resistant aminopeptidase activity (630 pmol leu-enk/min/mg protein). S2 contained 32 pmol leu-enk/min/mg activity, with 80% representing puromycin-resistant activity and 20% puromycin-sensitive aminopeptidase (PS-Ap). Ala-Ap was detected in both P2 and S2 fractions and was localized by zymography to epithelial and gland cells. Anti-rat brain-soluble PS-Ap IgG detected immunoreactive material in epithelium, glands, and endothelium. In nasal provocation studies, leu-AP correlated with glandular exocytosis but not vascular leak.


CONCLUSIONS
The predominant aminopeptidase in human nasal epithelial and submucosal gland cells was membrane-bound puromycin-resistant aminopeptidase. A novel soluble puromycin-resistant aminopeptidase and lower amounts of soluble PS-Ap were also detected.
Ohkubo
K
K
Department of Otolaryngology, Nippon Medical School, Tokyo, Japan.
Baraniuk
J N
JN
Hohman
R
R
Merida
M
M
Hersh
L B
LB
Kaliner
M A
MA
D000626:Aminopeptidases / Q000378:metabolism*; D000941:Antigens / Q000494:pharmacology; D001667:Binding, Competitive; D018826:CD13 Antigens / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006651:Histocytochemistry; D006801:Humans; D007150:Immunohistochemistry; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D007931:Leucyl Aminopeptidase / Q000037:antagonists & inhibitors / Q000378:metabolism; D017817:Nasal Lavage Fluid / Q000737:chemistry / Q000276:immunology; D009297:Nasal Mucosa / Q000201:enzymology*; D011480:Protease Inhibitors / Q000494:pharmacology; D011691:Puromycin / Q000494:pharmacology; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity; D014420:Turbinates / Q000201:enzymology
D000941:Antigens; D011480:Protease Inhibitors; D011691:Puromycin; D000626:Aminopeptidases; D007931:Leucyl Aminopeptidase; D018826:CD13 Antigens; D007930:Leucine; C012211:ubenimex