This first report of two independent genetic markers in nodal generalised OA is of interest in relation to the increasingly recognised inflammatory component of the osteoarthritis process.
In this study we investigated the synovial fluid plasma ratio of C4A and C4B of rheumatoid (RA) and osteoarthritis (OA) patients, and a predominance of the C4B gene expression by the synovial macrophages of RA patients was demonstrated.
Similar results were found using osteoarthritis ST cells, although the percentage of cells expressing the IL-6 gene (7.1 +/- 2.5%) was significantly less in osteoarthritis compared to RA.
HBGF-1 staining was more extensive and intense in synovium of RA patients than OA and correlated with the extent and intensity of synovial mononuclear cell infiltration.
The frequency of homozygous genotype for the 5.8 kb A1ACT band was increased in osteoarthritis (62.8% versus 36.8%, P = 0.01, relative risk = 2.9, aetiological fraction = 0.41).
We have, therefore, studied GM-CSF expression in cultures of cells derived from joints affected by RA and osteoarthritis (OA), and show that GM-CSF is produced spontaneously both by RA synovial cells and to a lesser extent by OA synovial cells in the absence of extrinsic stimuli.
IL-1 alpha and IL-1R1 expressing cells showed a similar distribution in OA synovial membrane, but there was a smaller number of positive cells in the deeper area; and the staining intensity was lower.
MCP-1 levels were significantly higher (P less than 0.05) in synovial fluid from RA patients (mean 25.5 +/- 8.1 ng/ml [SE]) compared to synovial fluid from osteoarthritis (OA) patients (0.92 +/- 0.08), or from patients with other arthritides (2.9 +/- 1.5).
Synovial tissues from donors without joint disease and from patients with rheumatoid or osteoarthritis were analyzed for MCP-1 mRNA expression by in situ hybridization.
IL-1 alpha and IL-1R1 expressing cells showed a similar distribution in OA synovial membrane, but there was a smaller number of positive cells in the deeper area; and the staining intensity was lower.
Biologically active LIF is present in synovial fluids from patients with osteoarthritis and at higher titers in samples from patients with rheumatoid arthritis.