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.
Lu
Y
Y
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.
Wang
W-J
WJ
Leng
J-H
JH
Cheng
L-F
LF
Feng
L
L
Yao
H-P
HP
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