Objectives To investigate the effects of interleukin-17 (IL-17) on the production of vascular endothelial growth factor (VEGF) from cultured rheumatoid arthritis synoviocytes.

Methods Fibroblast-like synovial cells (FLS) were prepared from the synovial tissues of rheumatoid arthritis patients and cultured in the presence of IL-17, transforming growth factor-b (TGF-b), tumour necrosis factor-α (TNF-α) and interleukin-1b (IL-1b). VEGF levels were determined in the culture supernatants by sandwitch ELISA.

Results Stimulation of FLS by serial concentration of IL-17, TGF-b, TNF-α, IL-1b increased the production of VEGF by 2.1–2.7, 2.2–3.0, 2.0–2.9, 2.3–3.1 fold over the constitutive levels of unstimulated FLS. Stimulation of FLS by IL-17 with TGF-b, TNF-α or IL-1b also increased the production of VEGF according to culture periods by 1.6–1.8, 1.1–1.9, 1.5–1.7 fold over the levels stimulated with TFG-b or TNF-α or IL-1b, respectively. This results indicated that IL-17 increased the effect of TGF-b, TNF-α, IL-1b on FLS, leading synergistic enhancement of VEGF production.

Conclusion IL-17 may be involved in the neovascularization in rheumatoid synovitis by enhancing the production of VEGF.