Autocrine activation of cortisol and the regulation of fibroblast function. Bone marrow, dermal and synovial fibroblasts were treated with vehicle (C), cortisol (F), or cortisone (E; both at 100 nmol/l) in the presence or absence of the 11b-HSD1 inhibitor glycyrrhetinic acid (+ G; 5 μmol/l) for 24 hours. Cells were then assessed expression of IL-6 mRNA and protein. (a) For mRNA analyses, target gene data were normalized for levels of the housekeeping gene 18S rRNA and presented as fold change in expression relative to vehicle-treated fibroblasts. (b) Analysis IL-6 protein secretion in synovial fibroblasts was carried out using a specific ELISA assay and reported as pg IL-6/mg cell protein/24 hours. Values are expressed as mean ± standard deviation of four replicates from a representative culture of rheumatoid arthritis fibroblasts. Similar values were obtained when the assays were carried out using two other fibroblast cells lines. *P < 0.01, **P < 0.001 versus vehicle-treated cells (statistical analysis carried out on unmodified ΔCt values). Ct = the cycle number at which logarithmic PCR plots cross a calculated threshold line; ELISA, enzyme-linked immunosorbent assay; 11β-HSD = 11β-hydroxysteroid dehydrogenase.