Modulation of 11beta-hydroxysteroid dehydrogenase isozymes by proinflammatory cytokines in osteoblasts: an autocrine switch from glucocorticoid inactivation to activation

J Bone Miner Res. 2001 Jun;16(6):1037-44. doi: 10.1359/jbmr.2001.16.6.1037.

Abstract

Tissue damage by proinflammatory cytokines is attenuated at both systemic and cellular levels by counter anti-inflammatory factors such as corticosteroids. Target cell responses to corticosteroids are dependent on several factors including prereceptor regulation via local steroidogenic enzymes. In particular, two isozymes of 11beta-hydroxysteroid dehydrogenase (11beta-HSD), by interconverting hormonally active cortisol (F) to inactive cortisone (E), regulate the peripheral action of corticosteroids 11beta-HSD1 by converting E to F and 11beta-HSD2 by inactivating F to E. In different in vitro and in vivo systems both 11beta-HSD isozymes have been shown to be expressed in osteoblasts (OBs). Using the MG-63 human osteosarcoma cell-line and primary cultures of human OBs, we have studied the regulation of osteoblastic 11beta-HSD isozyme expression and activity by cytokines and hormones with established roles in bone physiology. In MG-63 cells, interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) potently inhibited 11beta-HSD2 activity (cortisol-cortisone conversion) and messenger RNA (mRNA) levels in a dose-dependent manner while stimulating reciprocal expression of 11beta-HSD1 mRNA and activity (cortisone-cortisol conversion). A similar rise in 11beta-HSD1 reductase activity also was observed in primary cultures of OBs treated with 10 ng/ml TNF-alpha. Pretreatment of MG-63 cells with 0.1 ng/ml IL-1beta resulted in increased cellular sensitivity to physiological glucocorticoids as shown by induction of serum and glucocorticoid-inducible kinase (SGK; relative increase with 50 nM F but no IL-1beta pretreatment 1.12 +/- 0.34; with pretreatment 2.63 +/- 0.50; p < 0.01). These results highlight a novel mechanism within bone cells whereby inflammatory cytokines cause an autocrine switch in intracellular corticosteroid metabolism by disabling glucocorticoid inactivation (11beta-HSD2) while inducing glucocorticoid activation (11beta-HSD1). Therefore, it can be postulated that some of the effects of proinflammatory cytokines within bone (e.g., periarticular erosions in inflammatory arthritis) are mediated by this mechanism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 11-beta-Hydroxysteroid Dehydrogenases
  • Cells, Cultured
  • Cytokines / metabolism*
  • Cytokines / pharmacology
  • Enzyme Activation / drug effects
  • Glucocorticoids / metabolism*
  • Humans
  • Hydroxysteroid Dehydrogenases / drug effects
  • Hydroxysteroid Dehydrogenases / genetics
  • Hydroxysteroid Dehydrogenases / metabolism*
  • Immediate-Early Proteins
  • Inflammation / metabolism
  • Interleukin-1 / metabolism
  • Interleukin-1 / pharmacology
  • Isoenzymes / drug effects
  • Nuclear Proteins*
  • Osteoblasts / drug effects
  • Osteoblasts / metabolism*
  • Osteosarcoma / enzymology
  • Protein-Serine-Threonine Kinases / drug effects
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • Tumor Necrosis Factor-alpha / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Cytokines
  • Glucocorticoids
  • Immediate-Early Proteins
  • Interleukin-1
  • Isoenzymes
  • Nuclear Proteins
  • Tumor Necrosis Factor-alpha
  • Hydroxysteroid Dehydrogenases
  • 11-beta-Hydroxysteroid Dehydrogenases
  • Protein-Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase