Production of monocyte chemotactic protein-1 in human type B synoviocytes. Synergistic effect of tumor necrosis factor alpha and interferon-gamma.
OBJECTIVE
Since local secretion of chemotactic factors could contribute substantially to the homing of monocytes to the rheumatoid synovium, we investigated the ability of type B, or "fibroblast-like," synoviocytes isolated from the synovial tissue of patients with rheumatoid arthritis to synthesize and secrete the novel cytokine monocyte chemotactic protein 1 (MCP-1).


METHODS
Synthesis and secretion of MCP-1 was determined by immunoprecipitation following metabolic labeling of MCP-1 with 35S-cysteine. MCP-1 gene regulation was assessed by Northern blot analysis.


RESULTS
Unstimulated type B synoviocytes released little or no MCP-1, although low levels of MCP-1 messenger RNA (mRNA) were detected. However, incubation of these cells with tumor necrosis factor alpha (TNF alpha) resulted in a time- and dose-dependent release of MCP-1 into the supernatant, and expression of MCP-1 mRNA. Use of cycloheximide and actinomycin D confirmed that TNF alpha was inducing MCP-1 expression at both the transcriptional and translational levels. Treatment of the synoviocytes with interferon-gamma (IFN gamma) also stimulated an increase in both the steady-state levels of MCP-1 mRNA, as well as MCP-1 protein synthesis and secretion. In addition, TNF alpha and IFN gamma in combination exerted a synergistic effect on both MCP-1 mRNA accumulation and protein secretion.


CONCLUSIONS
These studies demonstrate that the MCP-1 gene is regulated by TNF alpha and IFN gamma in type B synoviocytes and indicate that these cells may play an important role in the recruitment of inflammatory cells to the rheumatoid synovial environment, via the production of novel chemotactic cytokines such as MCP-1.
Hachicha
M
M
Centre de Recherche en Inflammation, Université Laval, Ste. Foy, Quebec, Canada.
Rathanaswami
P
P
Schall
T J
TJ
McColl
S R
SR
D018932:Chemokine CCL2; D002630:Chemotactic Factors / Q000096:biosynthesis* / Q000235:genetics; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004357:Drug Synergism; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D013582:Synovial Fluid / Q000166:cytology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D018932:Chemokine CCL2; D002630:Chemotactic Factors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D007371:Interferon-gamma; D003513:Cycloheximide