11βhydroxysteroid dehydrogenase types 1 and 2 activity in subcutaneous adipose tissue in humans: Implications in obesity and diabetes

Context: The role of 11β-hydroxysteroid dehydrogenase types 1 (11β-HSD-1) and 2 (11β-HSD-2) enzymes in sc adipose tissue is controversial. Objective: The objective of the study was to determine the activity of 11β-HSD-1 and -2 enzymes in the abdominal and leg sc adipose tissue in obesity and diabetes. Design: 11β-HSD-1 and -2 enzyme activities in abdominal and leg sc adipose tissue were measured by infusing [2,2,4,6,6,12,12-2H7] cortisone (D7 cortisone) and [9,12,12-2H3] cortisol (D3 cortisol) via microdialysis catheters placed in sc fat depots. Setting: The study was conducted at the Mayo Clinic Clinical Research Unit. Participants: Lean nondiabetic (n = 13), overweight/obese nondiabetic (n = 15), and overweight/ obese participants with type 2 diabetes mellitus (n = 15) participated in the study. Main Outcome Measures: The conversion of infused D7 cortisone to D7 cortisol (via 11β-HSD reductase activity) and D3 cortisol to D3 cortisone (via 11β-HSD dehydrogenase activity) in sc adipose tissue. Results: Enrichment of D7 cortisone and D3 cortisol were similar in the effluents from both sites in all groups. D3 cortisone enrichment did not differ in the three cohorts, indicating that 11β-HSD-2 enzyme activity (conversion of cortisol to cortisone) occurs equally in all groups. However, D7 cortisol enrichment was detectable in abdominal sc fat of overweight/obese participants with type 2 diabetes mellitus only, implying 11β-HSD-1 reductase activity (conversion of cortisone to cortisol) occurs in obese subjects with type 2 diabetes. Conclusions: There is conversion of cortisone to cortisol via the 11β-HSD-1 enzyme pathway in abdominal sc fat depots in overweight/obese participants with type 2 diabetes mellitus. This observation has significant implications for developing tissue-specific 11β-HSD-1 inhibitors in type 2 diabetes mellitus.