Macrophage migration inhibitory factor up-regulates the expression of interleukin-8 messenger RNA in synovial fibroblasts of rheumatoid arthritis patients: common transcriptional regulatory mechanism between interleukin-8 and interleukin-1beta.
OBJECTIVE
Interleukin-8 (IL-8) plays an important role in the migration of inflammatory cells into the synovium and joint fluids in rheumatoid arthritis (RA). This study was undertaken to investigate the IL-8 inductive activity of the macrophage migration inhibitory factor (MIF) in RA synovial fibroblasts. The regulatory mechanism of IL-8 was compared with that of IL-1beta.


METHODS
MIF-induced IL-8 and IL-1beta transcriptional activation was studied in RA synovial fibroblasts by Northern blot analysis, enzyme-linked immunosorbent assay, and electromobility shift assay. The effect of anti-MIF antibody administration on murine passive collagen-induced arthritis (CIA) was also evaluated by histologic examination and reverse transcriptase-polymerase chain reaction.


RESULTS
MIF up-regulated the IL-8 messenger RNA (mRNA) and protein levels in a dose-dependent manner. The IL-8 mRNA up-regulation started 1 hour poststimulation by MIF, and reached a maximum level at 6 hours. IL-1beta mRNA was also up-regulated by MIF. The mRNA up-regulation of IL-8 and IL-1beta by MIF was inhibited by 2 tyrosine kinase inhibitors, a protein kinase C (PKC) inhibitor, an activator protein 1 (AP-1) inhibitor, and by an NF-kappaB inhibitor. A cAMP-dependent kinase inhibitor did not inhibit it. MIF enhanced AP-1 and NF-kappaB binding activities in a dose-dependent manner. Passive CIA enhanced mRNA levels of macrophage inflammatory protein 2 and cytokine-induced neutrophil chemoattractants and, moreover, migration and proliferation of inflammatory cells within the synovium, which were suppressed by administration of an anti-MIF antibody.


CONCLUSIONS
MIF may play an important role in the migration of inflammatory cells into the synovium of rheumatoid joints via induction of IL-8. MIF up-regulates IL-8 and IL-1beta mRNA via tyrosine kinase-, PKC-, AP-1-, and NF-kappaB-dependent pathways.
Onodera
Shin
S
Department of Molecular Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
Nishihira
Jun
J
Koyama
Yoshikazu
Y
Majima
Tokifumi
T
Aoki
Yoshimitsu
Y
Ichiyama
Hiroki
H
Ishibashi
Teruo
T
Minami
Akio
A
D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000503:physiopathology; D054426:Chemokine CXCL2; D018925:Chemokines; D016207:Cytokines / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000276:immunology; D015870:Gene Expression / Q000276:immunology; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000235:genetics*; D016209:Interleukin-8 / Q000235:genetics*; D008263:Macrophage Migration-Inhibitory Factors / Q000494:pharmacology*; D015846:Monokines / Q000235:genetics; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D020370:Osteoarthritis, Knee / Q000276:immunology / Q000503:physiopathology; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger / Q000378:metabolism; D012795:Sialoglycoproteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D013583:Synovial Membrane / Q000166:cytology / Q000276:immunology*; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D014158:Transcription, Genetic / Q000276:immunology; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
D054426:Chemokine CXCL2; D018925:Chemokines; D016207:Cytokines; D004791:Enzyme Inhibitors; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D016209:Interleukin-8; D008263:Macrophage Migration-Inhibitory Factors; D015846:Monokines; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D018808:Transcription Factor AP-1; C074302:keratinocyte-derived chemokines