Major enzymes controlling the androgenic pressure in the developing lung.

A sex difference is observed in the incidence and morbidity of respiratory distress syndrome (RDS) of the neonate and in bronchopulmonary dysplasia (BPD). The involvement of androgens is well evidenced in RDS and it is suspected in BPD. Interestingly, the developing lung is not an inert tissue just exposed to circulating androgens, but is rather an active androgen metabolizing tissue, expressing enzymes involved in both androgen synthesis and inactivation. The present review focuses on the major enzymes involved in androgen metabolism within the developing lung. Testosterone synthesis and inactivation by AKR1C3/Akr1c6 (human/mouse 17β-hydroxysteroid dehydrogenases (HSDs) type 5) and HSD17B2 (17β-HSD type 2), respectively, play an important role in the developing lung. Akr1c14 (3α-HSD) shows a strong increase in expression according to developmental time. The canalicular stage of lung development corresponding to the surge of surfactant lipid synthesis, which is linked to RDS, as well as saccularization/alveolarization, which are linked to BPD, are covered by this review for the mouse and human species. The androgen metabolizing enzymes expressed within the developing lung can become potential pharmaceutical targets in the objective of accelerating lung maturation by specific treatments. The classic deleterious effects of androgens on lung maturation and the surge of surfactant synthesis in males are well known. Conversely, androgens also have positive impacts on the development of both male and female lungs. Steroidogenic enzymes are key regulators of these positive effects. This article is part of a Special Issue entitled 'CSR 2013'.