We tested the impact of CD40 engagement on the production of vascular endothelial growth factor (VEGF) from rheumatoid synovial fibroblasts. Fibroblast-like synovial cells (FLS) were prepared from the synovial tissues of rheumatoid arthritis patients and cultured in the presence of CD40 ligand- transfected (CD40L+) L cells. VEGF levels were determined in the culture supernatants by ELISA. Stimulation of FLS by CD40L+ L cells increased the production of VEGF by 4.1-fold over the constitutive levels of unstimulated FLS. The CD40L on activated T cells from rheumatoid synovial fluid also up- regulated VEGF production from FLS. Neither indomethacin nor Abs to IL-1β, TNF-α, and TGF-β did affect CD40L-induced VEGF production. Stimulation of FLS with TNF-α, IL-β, and TGF-β increased VEGF production by 1.6-, 2.0-, and 5.2-fold, respectively, and displayed an additive effect on the production of VEGF by CD40L. VEGF mRNA expression was also up-regulated by the stimulation of FLS with membranes from the CD40L+ L cells. Dexamethasone completely abrogated CD40L-induced VEGF production. In addition, pyrrolidine dithiocarbamate partially down-regulated CD40L-induced VEGF production, showing that the NF-κ pathway was partly involved in the signaling of CD40L leading to VEGF production. Collectively, these results suggest that the interaction between CD40 on synovial fibroblasts and CD40L expressed on activated T lymphocytes may be directly involved in the neovascularization in rheumatoid synovitis by enhancing the production of VEGF.
ASJC Scopus subject areas
- Immunology and Allergy