Interleukin-32, CCL2, PF4F1 and GFD10 are the only cytokine/chemokine genes differentially expressed by in vitro cultured rheumatoid and osteoarthritis fibroblast-like synoviocytes.

Since cytokines and chemokines are important actors in rheumatoid arthritis (RA), the aim of this study was to compare the gene expression profiles in cultured fibroblast-like synoviocytes (FLS) obtained from patients with either RA, or osteoarthritis (OA), focusing our analysis on genes for cytokines and chemokines, and their respective receptors. Gene expression in cultured FLS (third passage) from eight patients with RA (RA-FLS) were compared with gene expression in cultured FLS from nine patients with OA (OA-FLS) using Affymetrix Human Genome U133 Plus 2.0 Array microarray, allowing analysis of over 54,000 transcripts. Among the 171 genes studied (241 probes), limiting the selection of differentially expressed genes to a significant value (p < 0.05), and a differential ratio of expression > 1.6, only four genes, namely IL-32, CCL2, PF4F1 and GDF10 were found to be differentially expressed. Out of these four genes, only higher expression of CCL2 has been reported previously in RA. The newly described cytokine IL-32 was the most prominently differentially expressed gene in the present study, with higher expression in RA-FLS than in OA-FLS (p < 0.0073). IL-32 might have a previously unidentified pivotal role in RA.