Inhibitory effect of triptolide on interleukin-18 and its receptor in rheumatoid arthritis synovial fibroblasts.
OBJECTIVE
To determine the effects of triptolide (TP) on the expression of interleukin-18 (IL-18) and its receptor in phorbol 12-myristate 13-acetate (PMA)-stimulated rheumatoid arthritis synovial fibroblasts (RASF).


METHODS
RASF were obtained from the synovial tissue of patients with RA. RASF were pretreated with TP (0~100 ng/ml) for 2 h before stimulation with PMA (50 ng/ml). The bioactivity of IL-18 in the supernatant was detected based on IFN-gamma secretion from IL-18-responding human myelomonocytic KG-1 cells. IL-18 level was analyzed by ELISA. In situ expression of IL-18Ralpha was determined by immunofluorescence assay. To estimate the protein and mRNA expression of IL-18 and IL-18Ralpha in RASF, western blot and quantitative RT-PCR were performed. Nuclear factor-kappaB (NF-kappaB) activity in the whole-cell extract of treated RASF was also measured using an ELISA-based method.


RESULTS
TP effectively inhibited the bioactivity of IL-18 in PMA-stimulated RASF. The expression of IL-18 and IL-18R at protein and gene levels was reduced by TP. NF-kappaB activity in PMA-stimulated RASF was profoundly suppressed by TP. These effects showed a high correlation with TP concentration (0~100 ng/ml).


CONCLUSIONS
TP effectively inhibited the expression of IL-18 and its receptor in PMA-stimulated RASF. These results suggest a mechanism of TP in RA therapy.
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Institute of Infectious Diseases, the First Affiliated Hospital, Zhejiang University School of Medicine, 79 Qingchun Road, Hangzhou 310003, China.
Y
Y
Lu
W-J
WJ
Wang
J-H
JH
Leng
L-F
LF
Cheng
L
L
Feng
H-P
HP
Yao
D000818:Animals; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000473:pathology; D002478:Cells, Cultured; D004224:Diterpenes / Q000378:metabolism* / Q000494:pharmacology; D004852:Epoxy Compounds / Q000378:metabolism / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007166:Immunosuppressive Agents / Q000378:metabolism* / Q000494:pharmacology; D020382:Interleukin-18 / Q000235:genetics / Q000276:immunology*; D010616:Phenanthrenes / Q000378:metabolism* / Q000494:pharmacology; D053724:Receptors, Interleukin-18 / Q000235:genetics / Q000276:immunology*; D013583:Synovial Membrane / Q000166:cytology*; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism
D004224:Diterpenes; D004852:Epoxy Compounds; D007166:Immunosuppressive Agents; D020382:Interleukin-18; D010616:Phenanthrenes; D053724:Receptors, Interleukin-18; D051996:Transcription Factor RelA; C001899:triptolide; D013755:Tetradecanoylphorbol Acetate