Differential expression, function and response to inflammatory stimuli of 11beta-hydroxysteroid dehydrogenase type 1 in human fibroblasts: a mechanism for tissue-specific regulation of inflammation.
Hardy RS., Filer A., Cooper MS., Parsonage G., Raza K., Hardie DL., Rabbitt EH., Stewart PM., Buckley CD., Hewison M.
Stromal cells such as fibroblasts play an important role in defining tissue-specific responses during the resolution of inflammation. We hypothesized that this involves tissue-specific regulation of glucocorticoids, mediated via differential regulation of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Expression, activity and function of 11beta-HSD1 was assessed in matched fibroblasts derived from various tissues (synovium, bone marrow and skin) obtained from patients with rheumatoid arthritis or osteoarthritis. 11beta-HSD1 was expressed in fibroblasts from all tissues but mRNA levels and enzyme activity were higher in synovial fibroblasts (2-fold and 13-fold higher mRNA levels in dermal and synovial fibroblasts, respectively, relative to bone marrow). Expression and activity of the enzyme increased in all fibroblasts following treatment with tumour necrosis factor-alpha or IL-1beta (bone marrow: 8-fold and 37-fold, respectively, compared to vehicle; dermal fibroblasts: 4-fold and 14-fold; synovial fibroblasts: 7-fold and 31-fold; all P < 0.01 compared with vehicle). Treatment with IL-4 or interferon-gamma was without effect, and there was no difference in 11beta-HSD1 expression between fibroblasts (from any site) obtained from patients with rheumatoid arthritis or osteoarthritis. In the presence of 100 nmol/l cortisone, IL-6 production--a characteristic feature of synovial derived fibroblasts--was significantly reduced in synovial but not dermal or bone marrow fibroblasts. This was prevented by co-treatment with an 11beta-HSD inhibitor, emphasizing the potential for autocrine activation of glucocorticoids in synovial fibroblasts. These data indicate that differences in fibroblast-derived glucocorticoid production (via the enzyme 11beta-HSD1) between cells from distinct anatomical locations may play a key role in the predeliction of certain tissues to develop persistent inflammation.