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Adhesion factors and endothelial growth factor vary with RA type

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Distinct histological forms of rheumatoid arthritis (RA) may respond differently to treatment as they have different patterns of soluble adhesion factors and vascular endothelial growth factor (VEGF), Polish researchers claim.

Their investigations centred on synovial and serum samples from 42 patients with RA and 32 controls with osteoarthritis (OA). Serum concentrations of soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular adhesion molecule 1 (sVCAM-1), soluble E-selectin (sE-selectin), and VEGF were significantly higher in patients with RA than OA. All except sE-selectin were much higher for patients with RA showing follicular synovitis (16) compared with patients showing diffuse synovitis (24) and patients with OA. They were also linked with clinical markers for RA, including erythrocyte sedimentation rate, C reactive protein, number of swollen joints, and x ray evidence indicating more severe disease.

In follicular RA the synovium contained circular aggregates of lymphocytes around a central core and associated with new capillaries. In diffuse synovitis and OA it showed a more uniform spread of mononuclear cells throughout the tissue.

Synovial tissue was taken from patients during hip or knee operations. Serum concentrations of adhesion factors and VEGF were measured by ELISA.

Distinct types of synovitis seem to be found with different patterns of cytokines in the synovium and cytokines and metalloproteinases in serum. Macrophages and fibroblasts migrate to the synovium under the influence of adhesion molecules and increased vascularisation promoted by VEGF, sVCAM, and sE-selectin. Once there their cytokines and metalloproteinases mediate tissue destruction, maybe controlled by lymphocytes.

Figure1

Typical histopathological appearance of synovial tissue. (A, C) uniform spread of mononuclear cells in RA or OA, respectively; (B) follicular arrays in RA. Original magnification × 100.

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