Predominant activation of MAP kinases and pro-destructive/pro-inflammatory features by TNF alpha in early-passage synovial fibroblasts via TNF receptor-1: failure of p38 inhibition to suppress matrix metalloproteinase-1 in rheumatoid arthritis.
OBJECTIVE
To examine the relative importance of tumour necrosis factor-receptor 1 (TNF-R1) and TNF-R2 and their signalling pathways for pro-inflammatory and pro-destructive features of early-passage synovial fibroblasts (SFB) from rheumatoid arthritis (RA) and osteoarthritis (OA).


METHODS
Cells were stimulated with tumour necrosis factor (TNF)alpha or agonistic anti-TNF-R1/TNF-R2 monoclonal antibodies. Phosphorylation of p38, ERK and JNK kinases was assessed by western blot; proliferation by bromodesoxyuridine incorporation; interleukin (IL)6, IL8, prostaglandin E(2) (PGE(2)) and matrix metalloproteinase (MMP)-1 secretion by ELISA; and MMP-3 secretion by western blot. Functional assays were performed with or without inhibition of p38 (SB203580), ERK (U0126) or JNK (SP600125).


RESULTS
In RA- and OA-SFB, TNFalpha-induced phosphorylation of p38, ERK or JNK was exclusively mediated by TNF-R1. Reduction of proliferation and induction of IL6, IL8 and MMP-1 were solely mediated by TNF-R1, whereas PGE(2) and MMP-3 secretion was mediated by both TNF-Rs. In general, inhibition of ERK or JNK did not significantly alter the TNFalpha influence on these effector molecules. In contrast, inhibition of p38 reversed TNFalpha effects on proliferation and IL6/PGE(2) secretion (but not on IL8 and MMP-3 secretion). The above effects were comparable in RA- and OA-SFB, except that TNFalpha-induced MMP-1 secretion was reversed by p38 inhibition only in OA-SFB.


CONCLUSIONS
In early-passage RA/OA-SFB, activation of MAPK cascades and pro-inflammatory/pro-destructive features by TNFalpha is predominantly mediated by TNF-R1 and, for proliferation and IL6/PGE(2) secretion, exclusively regulated by p38. Strikingly, RA-SFB are insensitive to p38 inhibition of MMP-1 secretion. This indicates a resistance of RA-SFB to the inhibition of pro-destructive functions and suggests underlying structural/functional alterations of the p38 pathway, which may contribute to the pathogenesis or therapeutic sensitivity of RA, or both.
Kunisch
Elke
E
Experimental Rheumatology Unit, Department of Orthopaedics, Friedrich Schiller University Jena, Klosterlausnitzer Str. 81, D-07607 Eisenberg, Germany.
Gandesiri
Muktheshwar
M
Fuhrmann
Reneé
R
Roth
Andreas
A
Winter
Rando
R
Kinne
Raimund W
RW
D000873:Anthracenes / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000201:enzymology* / Q000276:immunology; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D016022:Case-Control Studies; D002478:Cells, Cultured; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020781:Matrix Metalloproteinase 1 / Q000032:analysis / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D009570:Nitriles / Q000494:pharmacology; D010003:Osteoarthritis / Q000201:enzymology / Q000276:immunology; D011725:Pyridines / Q000494:pharmacology; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism*; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D018709:Statistics, Nonparametric; D013583:Synovial Membrane / Q000201:enzymology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D000873:Anthracenes; D002070:Butadienes; D004791:Enzyme Inhibitors; D007093:Imidazoles; D061965:Matrix Metalloproteinase Inhibitors; D009570:Nitriles; D011725:Pyridines; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; C113580:U 0126; C432165:pyrazolanthrone; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020781:Matrix Metalloproteinase 1; C093642:SB 203580