11-hydroxysteroid dehydrogenase, not steroidogenesis, increases glucocorticoid exposure during wound healing

Program: Late-Breaking Abstracts
Session: MON-LB-Late-Breaking Poster Session 3
Bench to Bedside
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-LB-03
Ana Tiganescu*, Melanie Hupe, Yoshikazu Uchida, Peter M Elias and Walter Holleran
UCSF-VA Medical Centre, San Francisco
Glucocorticoid (GC) excess inhibits wound healing (WH) causing increased patient discomfort and infection risk. The ubiquitously-expressed enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activates GC in many tissues including skin, where steroidogenesis is also suggested to contribute to local GC availability. The profiles of 11β-HSD1 and steroidogenesis during WH have not been investigated.

Following ethical approval, two 5mm full-thickness dorsal wounds were generated in female SKH1-HR mice and collected with unwounded skin on day 0 (0d), 2d, 4d, 8d, 14d and 21d. 11β-HSD1, cofactor-supplying hexose-6-phosphate dehydrogenase (H6PDH) and glucocorticoid receptor (GR) mRNA were analysed by qPCR (normalized to 18S rRNA) alongside 6 key enzymes (Star, Cyp11a1, Hsd3B6, Cyp17a1, Cyp21a1 and Cyp11b1) required for sequential cholesterol conversion to GC (n=4-13). 11β-HSD1 protein expression and localization were examined by Western blot (n=6, normalized to β-actin) and immunohistochemistry (n=3) respectively, with activity determined by radiometric conversion of 100nM 11-dehydrocorticosterone to corticosterone (n=4). Radiometric metabolism of 100nM progesterone was analysed in parallel (n=4).

Wound 11β-HSD1 mRNA were elevated 10-fold at 2d (p<0.001), 3-fold at 4d (p<0.001) and comparable to unwounded skin from 8d onwards, with negligible changes in H6PDH and GR. 11β-HSD1 protein increased accordingly and localized predominantly to inflammatory infiltrate, with activity increasing 2.5-fold in 2d (p<0.001) and 4d (p<0.01) wounds, generating >1.2pmol corticosterone/h and positively correlating to wound area (p<0.05).

Star and Cyp21a1 mRNA increased in 2d (2-fold, p<0.05 and 25-fold p<0.001) and 4d (2.5-fold, p<0.05 and 5-fold, p<0.001) wounds. Cyp17a1 decreased >50% in d4 (p<0.01) and d8 (p<0.001) wounds. Importantly, Cyp11b1 message was undetectable resulting in progesterone metabolism to 11-deoxycorticosterone (0.36±0.07pmol/h), not corticosterone (<0.02±0.005pmol/h) with similar findings during WH.

11β-HSD1 is the primary generator of GC in mouse skin, activating >30-fold more corticosterone than synthesized from progesterone. Increased 11β-HSD1 activity during WH forms the basis for topical 11β-HSD1 blockade to accelerate healing.

(1) Tiganescu A et a., JCI 2013 (in press), 11ß-hydroxysteroid dehydrogenase blockade prevents age-induced skin structure and function defects.

Nothing to Disclose: AT, MH, YU, PME, WH

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm