Lipoxin A4 counteracts synergistic activation of human fibroblast-like synoviocytes.
Excessive production of interleukin-6 (IL-6) and metalloproteinases (MMPs) have been implicated in the pathogenesis of rheumatoid arthritis. Lipoxin A4 (LXA4) and transforming growth factor beta 2 (TGF-beta 2), mediators with potential anti-inflammatory activities, were tested to determine how they affect IL-1 beta-dependent release of IL-6 and MMPs in human fibroblast like synoviocytes. The results showed dramatic differences between the mediators: TGF-beta 2 acted synergistically with IL-1 beta to stimulate IL-6 protein levels, whereas LXA4 inhibited IL-6 expression in dose- and time-dependent manner. Inhibition, by LXA4 was abrogated when cells were pre-incubated with antibody against the LXA4R whereas TGF-beta 2 by itself had no significant effect on IL-6 or MMP levels. LXA4, at nanomolar concentrations, altered the MMP-1 and MMP-3 expression levels of IL-1 beta and TGF-beta 2 stimulated fibroblast like synoviocytes at 5 days. Furthermore, IL-1 beta and TGF-beta 2 up-regulated LXA4R mRNA. These results demonstrate, for the first time, that LXA4Rs mediate the effects of LXA4 on inflammatory responses after combined stimulation of human fibroblast like synoviocytes with IL-1 beta and TGF-beta 2. These activities might constitute an important mechanism by which LXA4 regulates human synovial fibroblast activation.
Department of Medicine/Rheumatology, COM, University of Illinois, Chicago, IL 60607, USA.
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S
Sodin-Semrl
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A
Spagnolo
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B
Barbaro
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J
Varga
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S
Fiore
D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology; D015850:Interleukin-6 / Q000502:physiology; D044045:Lipoxins / Q000502:physiology*; D045726:Metalloproteases / Q000378:metabolism; D013582:Synovial Fluid / Q000166:cytology* / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000502:physiology; D053781:Transforming Growth Factor beta2
D007375:Interleukin-1; D015850:Interleukin-6; D044045:Lipoxins; C509041:TGFB2 protein, human; D016212:Transforming Growth Factor beta; D053781:Transforming Growth Factor beta2; C040527:lipoxin A4; D045726:Metalloproteases