Objective：To investigate the in vitro effects of interleukin-27（IL-27） on the pro-inflammatory activation of human fibroblast-like synoviocytes（FLS），and the underlying intracellular signaling molecules. Methods：After treatment of human FLS with IL-27，concentration of IL-6 in culture supernatant was measured by ELISA. FLS were treated with signal pathway inhibitor for 1 hour，and then treated with IL-27 for 48 hours, and the supernatant of IL-6 was detected by ELISA. IL-27 treatment of FLS at different time points，the intracellular signaling pathway phosphorylation level was detected by Western blot. Results：IL-27 could significantly induce the release of IL-6 from both N-FLS and RA-FLS（P=0.001，P=0.001）. and the concentration of IL-6 induced by IL-27（50 ng/mL）in both N-FLS（1329.10±113.15） pg/mL and RA-FLS（1583.70±129.54） pg/mL were higher than those of negative control group. Different concentrations of （0，10，20，50，100 ng/mL） IL-27 were used to treat cells at different times（0，12，24，48 h），and it was in a dose and time dependant manner. Further study showed that the IL-6 induced by IL-27 could be significantly suppressed by JAK inhibitor AG490 and JNK inhibitor SP600125 in both N-FLS and RA-FLS. Phosphorylation of the intracellular signaling proteins JAK2 and JNK is significantly increased after IL-27 treatment in both N-FLS and RA-FLS（JAK2：F=303.000，P=0.000；F=640.400，P=0.000；JNK：F=98.840，P=0.000，F=54.820，P=0.001）. Conclusion：IL-27 has the potential to amplify arthritis inflammation via the up-regulates the release of IL-6 from FLS by activating JAK2 and JNK signaling pathways.
