Preventing local regeneration of glucocorticoids by 11β-hydroxysteroid dehydrogenase type 1 enhances angiogenesis

Angiogenesis restores blood flow to healing tissues, a process that is inhibited by high doses of glucocorticoids. However, the role of endogenous glucocorticoids and the potential for antiglucocorticoid therapy to enhance angiogenesis is unknown. Using in vitro and in vivo models of angiogenesis in mice, we examined effects of (i) endogenous glucocorticoids, (h) blocking endogenous glucocorticoid action with the glucocorticoid receptor antagonist RU38486, and (iii) abolishing local regeneration of glucocorticoids by the enzyme 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta HSD1). Glucocorticoids, administered at physiological concentrations, inhibited angiogenesis in an in vitro aortic ring model and in vivo in polyurethane sponges implanted s.c. RU38486-enhanced angiogenesis in s.c. sponges, in healing surgical wounds, and in the myocardium of mice 7 days after myocardial infarction induced by coronary artery ligation. 11 beta HSD1 knockout mice showed enhanced angiogenesis in vitro and in vivo within sponges, wounds, and infarcted myocardium. Endogenous glucocorticoids, including those generated locally by 11 beta HSD1, exert tonic inhibition of angiogenesis. Inhibition of 11 beta HSD1 in liver and adipose has been advocated to reduce cardiovascular risk in the metabolic syndrome: these data suggest that 11 beta HSD1 inhibition offers a previously uncharacterized therapeutic approach to improve healing of ischemic or injured tissue.