Am. J. Respir. Crit. Care Med.,
Volume 165, Number 7, April 2002, 1010-1014
Clinical Relevance of Airway 11
-Hydroxysteroid
Dehydrogenase Type II Enzyme in Asthma
BERNADETTE E.
ORSIDA,
ZYGMUNT S.
KROZOWSKI,
and
E.
HAYDN WALTERS
Department of Respiratory Medicine, The Alfred Hospital and Monash University Medical School; Laboratory of Molecular Hypertension,
Baker Medical Research Institute, Melbourne; and Department of Clinical Sciences, University of Tasmania Medical School,
Royal Hobart Hospital, Tasmania, Australia
11
-Hydroxysteroid dehydrogenases (11
-HSD) are responsible for
the conversion of bioactive glucocorticoids to and from inactive metabolites. 11
-HSD2 is generally considered a high-affinity inactivator of natural glucocorticoids, although its activity with synthetic compounds in vivo is unknown. Inhaled corticosteroids (ICS)
remain the primary antiinflammatory agents for treating asthma,
but little is known about their metabolism in the lung. The aims of
this study were to determine whether the 11
-HSD2 enzyme can
be localized to human airway tissue and whether differential expression of this enzyme relates to asthma severity and ICS needs. We studied airway biopsy specimens from 22 asthmatic subjects, in
two groups: (1) a group not treated with ICS (n = 7); and (2) a
group treated with ICS (range: 200 to 1,500 µg/d; n = 15). A control
population consisted of nine nonasthmatic subjects. Immunostaining was done with an immunopurified antibody to human 11
-HSD2.
Immunoreactivity was generally localized to the endothelium of
vessels in the lamina propria and to airway epithelium both in
asthmatic patients and nonasthmatic controls. There was a statistically significant inverse relationship between the ICS dose required
for effective treatment and the extent of epithelial 11
-HSD2
staining (r =
0.44; p = 0.04). This is consistent with 11
-HSD2
acting as an oxidoreductase that regenerates rather than inactivates
ICS. This study suggests that glucocorticoid sensitivity in the lung is
not determined by ICS breakdown, but may be related to 11
-HSD2 sustaining the activation of synthetic glucocorticoids.