Localization of human glucocorticoid receptor in rheumatoid synovial tissue of the knee joint

Objective: This study was conducted to investigate the localization of human glucocorticoid receptors (GCRs) in the knee synovium of patients with rheumatoid arthritis ( RA) and to evaluate the correlation between GCR expression and the clinical profiles. Methods: Twenty synovial specimens from RA knees, six from knees with osteoarthritis (OA), and five from knees with traumatic arthritis ( TA) were obtained at surgery. The GCRs were stained immunohistochemically. The immunopositive cells were counted at random in the lining (synoviocytes) and sublining layers (fibroblastic and lymphoid cells). The relationship between the GCR-expressing cells and clinical profiles was analysed statistically. Results: GCRs were expressed in the nuclei of synoviocytes and the fibroblastic and lymphoid cells in the sublining layer. The GCR-positivity rate of synoviocytes was 67.1 +/- 18.4% in RA, 58.7 +/- 13.5% in OA, and 49.4 +/- 19.7% in TA, differences between the three groups being statistically insignificant. There was a significant difference in the GCR-positivity rate of sublining fibroblastic cells (p=0.029), but not synoviocytes or sublining lymphoid cells, from RA patients treated with and without prednisolone, while there was no correlation between the rate for synoviocytes and that for sublining fibroblastic cells from RA patients treated with prednisolone. Conclusions: GCRs are localized not only on inflammatory lymphoid cells but also on synoviocytes, suggesting that glucocorticoids could act directly on these cells. Furthermore, the rate of GCR expression on synoviocytes and sublining lymphoid cells is less suppressed with low-dose prednisolone, regardless of the duration of treatment.