Endocrine Abstracts

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterised by progressive joint destruction and inflammatory activation and hyperproliferation of synoviocytes. We have previously reported a marked shift towards reduced local androgen metabolism in active RA, driven by changing expression of SRD5A1 and AKR1C3 within macrophages. In this study we examined the role of altered androgen metabolism and availability in the inflammatory function of both macrophages and fibroblast-like synoviocytes (FLS).

Methods: Primary cultures of rheumatoid FLS and peripheral blood monocyte derived macrophages, were stimulated with the pro-inflammatory factor TNFα (10 ng/ml) in combination to incubation with either androstenedione (A4) (100 nmol/l), testosterone (T) (100 nmol/l) or dihydrotestosterone (DHT) (10 nmol/l) for up to 48 hours. Inflammatory gene expression was determined by qRT-PCR and ELISA. Viability and phagocytosis were assessed by MTT and colorimetric assays respectively. FLS proliferation, viability and migration were assessed in a Countess 3 cell counter and via scratch assay.

Results: Macrophages were unresponsive to the actions of androgens and androgen pre-cursors on viability, phagocytosis and inflammatory cytokine output following stimulation with TNFα. In contrast, following stimulation with TNFα treatment with both testosterone and DHT markedly reduced proliferation (15%, P<0.05) in FLS, increased migration (12%, P<0.05), without impacting on cell viability or live dead cell counts. Whilst the mRNA expression of inflammatory mediators did not change using this setup, a significant reduction in secreted IL-6 were apparent secondary to reduced cell numbers.

Conclusions: This study reveals a previously unreported effect of active androgens in suppressing the inflammatory hyper-proliferation of rheumatoid FLS. These data suggest that the reduced activation of androgens within the synovium in patients with RA may contribute to synovitis and progressive joint destruction.