11β-hydroxysteroid dehydrogenase type 2 in human lung:: Possible regulator of mineralocorticoid action

11 beta-Hydroxysteroid dehydrogenase type 2 (11 beta HSD2) catalyzes the conversion of cortisol to biologically inactive cortisone and is thought to confer specificity on mineralocorticoid receptors (MR). Cortisol is a prerequisite for surfactant synthesis and fetal lung maturation. Recently, expression of 11 beta HSD2 was demonstrated in human fetal lung, but its localization and possible biological roles remain unknown. Therefore, in this study, we examined immunohistochemical localization of 11 beta HSD2, MR, and glucocorticoid receptor (GR) in nonpathological human lungs from fetus to adult (8 weeks gestation to 55 yr of age; n = 40) retrieved om pathology files. Both 11 beta HSD2 and MR immunoreactivities were detected in airway epithelia, from bronchiole to trachea and in fetal and neonatal ciliated collecting duct cells of tracheal and bronchial glands, but were undetectable in alveoli. On the other hand, GR was detected in all cell types. These results indicate that 11 beta HSD2 colocalizes with MR in human airway epithelia and suggest that 11 beta HSD2 play an important role in pulmonary mineralocorticoid activity such as sodium and fluid transport.