Rheumatoid arthritis (RA) is an inflammatory disorder of the diarthroidial joints, characterized by fibroblast proliferation, angiogenesis, and perivascular CD4+ T cell infiltration. The present study examined the interactions between fibroblast growth factor-1 (FGF-1) and T cells.
Synovial tissues from patients with RA or noninflammatory arthritis were examined for the expression of FGF-1 and its receptor, FGFR-1, by immunohistology and reverse transcriptase-polymerase chain reaction. Functional assays were used to detect enrichment of FGF-1-responsive peripheral CD4+ T cells in RA.
FGF-1 is abundantly expressed by rheumatoid synovium. Enhanced expression of its receptor, FGFR-1, was found in perivascular CD4+ T cells. In addition, T cells that are activated by FGF-1 are increased in the peripheral blood of patients with RA, as compared with other inflammatory conditions.
The increased frequency of peripheral T cells that respond to FGF-1 in RA is consistent with expansion of FGFR-1-expressing T cells in the rheumatoid synovium.