Cytokine mRNA and protein expression in primary-culture and repeated-passage synovial fibroblasts from patients with rheumatoid arthritis

Constitutive mRNA expression and secretion of proinflammatory and anti-inflammatory cytokines was comparatively analyzed in rheumatoid arthritis (RA) synovial fibroblasts (SFB), isolated from primary culture or derived by repeated passage; normal-skin fibroblasts were used as controls. First-passage RA-SFB (n = 3) secreted large amounts of IL-6 (15,800 ± 2,110 pg/ml; mean ± SEM), but only limited amounts of tumor necrosis factor (TNF)-α (22.1 ± 1.1 pg/ml) or IL-10 (35.7 ± 34.2 pg/ml; only one of three samples was positive). IL-1β, IL-15, and IL-18 were not detectable at the protein level and showed very low mRNA levels by semiquantitative RT-PCR. In repeated-passage RA-SFB (tenth passage), protein secretion was significantly lower for IL-6 (one-twentieth of the initial level) and TNF-α (two-thirds), and markedly reduced for IL-10 (one-quarter, with only one of three samples positive). While the decrease of IL-10 protein from first to tenth passage was paralleled by a corresponding decrease of mRNA, the relative mRNA levels for IL-6 and TNF-α were actually increased (20-fold and 300-fold, respectively), indicating post-transcriptional and/or post-translational regulation of these cytokines. Due to highly variable levels among individual patients, however, no significant differences were observed for any cytokine mRNA between primary-culture and repeated-passage RA-SFB (ninth passage). Likewise, no significant differences were detectable between RA-SFB and normal-skin fibroblasts (primary-culture and repeated-passage). By producing high amounts of IL-6 and limited amounts of TNF-α, RA-SFB may contribute to the (im)balance of proinflammatory and anti-inflammatory cytokines in the inflamed joint.

                                            [
  "009:25"
]
                                        

                                            {
  "fn": "NIH",
  "@type": "vcard:Contact",
  "hasEmail": "mailto:info@nih.gov"
}
                                        

                                            [
  {
    "@type": "dcat:Distribution",
    "title": "Official Government Data Source",
    "mediaType": "text/html",
    "description": "Visit the original government dataset for complete information, documentation, and data access.",
    "downloadURL": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC83845/"
  }
]
                                        

                                            [
  "cytokine-expression",
  "il-6",
  "nih",
  "rheumatoid-arthritis",
  "synovial-fibroblasts"
]
                                        

                                            [
  "009:033"
]
                                        

                                            {
  "name": "National Institutes of Health",
  "@type": "org:Organization"
}
                                        

                                            [
  "NIH"
]