Differential expression patterns of secreted frizzled related protein genes in synovial cells from patients with arthritis

To detect expression of the secreted frizzled related protein (sFRP) gene in synovial cells from patients with arthritis.

Expression of sFRP-1, 2, 3, 4, and 5 genes was detected in synovial cells from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. To identify synovial cell populations expressing sFRP-1, 3, and 4 genes, expression was compared in macrophage-rich populations and fibroblast-like cell-rich populations by RT-PCR. Levels of expression of these genes were also studied in activated peripheral blood mononuclear cells (PBMC) and activated skin fibroblasts.

Expression of the sFRP-1, 3, and 4 genes was observed in both RA and OA synovial cells. sFRP-1 and 4 genes were expressed predominantly in fibroblast-like cell-rich populations, and the sFRP-3 gene was expressed predominantly in macrophage-rich populations. Levels of expression of sFRP-3 and 4 genes were elevated in activated PBMC and activated skin fibroblasts.

Our findings suggest that sFRP-1, 3, and 4 may play different roles in the pathogenesis of synovitis.