Increased levels of enzymes involved in local estradiol synthesis in chronic obstructive pulmonary disease.

INTRODUCTION: Steroid hormones are involved in lung development, pulmonary inflammation, and lung cancer. Estrogen signaling and exposure may play a role in pulmonary disorders, including COPD. In both genders, estrogens can be generated locally in the lungs and this contributes importantly to the tissue exposure to these steroids. OBJECTIVE: To characterize and assess differences in localization of estrogen receptors and enzymes involved in the local generation of estrogens in COPD. METHODS: Estrogen Receptor alpha (ERα/ESR1), Estrogen Receptor beta (ERß/ESR2) and G-protein-coupled estrogen receptor 1 (GPER) were explored by real-time (RT)-PCR analysis (mRNA expression), immunohistochemistry and western blotting in controls and COPD patients. mRNA expression of the enzymes involved in the local estrogen generation - i.e. aromatase (CYP19A1), 17beta-hydroxysteroid dehydrogenases (17ß-HSDs) 1, 2, 4, 5, 7 and 12, steroid sulfatase (STS) and sulfotransferase (SULT1E1) - were analyzed by RT-PCR. RESULTS: ERα, ERß and GPER were expressed in lung tissue, but no differences were observed between patients and controls. The main enzymes involved in local estrogen generation were also present in both normal and COPD lung tissue. In lungs of COPD patients compared with controls, we observed increased expression of the enzymes 17ß-HSD type 1 and aromatase (positive association), both involved in the local synthesis of active estrogens. CONCLUSION: All ER subtypes are present in the lung. The shift in local mRNA level of estrogen metabolic enzymes suggests that exposure to estrogens is involved in the pathogenesis of COPD.