[Role of NK-22 cells and interleukin-22-related molecules in proliferation of fibroblast- like synoviocytes in patients with rheumatoid arthritis].
OBJECTIVE
To investigate the role of natural killer-22 (NK-22) cells in the synovial fluid in the proliferation of fibroblast-like synoviocytes (FLS) in patients with rheumatoid arthritis (RA) and explore the possible signal pathway involved.


METHODS
NK-22 cells in the SF of RA patients were sorted by flow cytometry. NK-22 cells were cultured for two weeks and the purity was detected by flow cytometry before stimulation with 20 ng/ml phorbol 12-myristate 13-acetate and 0.5 µmol/L ionomycin for 4 h. The level of interleukin-22 (IL-22) in the culture medium supernatant was then measured with ELISA. The proliferation of FLS in the presence of the culture supernatant of NK-22 cells was assessed with MTT assay at 24, 48 and 72 h, and the effect of IL-22 antibody on FLS proliferation was also observed. Real-time PCR and Western blotting were used to detect Stat3 mRNA and p-Stat3 protein levels, respectively, in the FLS exposed to rhIL-22 and AG490.


RESULTS
NK-22 cells were successfully sorted by flow cytometry with a purity exceeding 90%. The levels of IL-22 in the supernatant of NKp44(+)NK cell culture averaged 1273.42∓254.48 pg/ml. The FLS proliferated rapidly 24, 48, and 72 h after the addition of culture supernatant of NK-22 cells (P<0.05). IL-22 antibody obviously inhibited the proliferation of FLS induced by NK-22 cell culture supernatant (P<0.05). Exposure of the FLS to rhIL-22 obviously increased cellular Stat3 expression levels, which were significantly lowered by the addition of AG490 (P<0.05).


CONCLUSIONS
NK-22 cells in the SF of RA patients can produce high concentrations of IL-22 to promote the proliferation of FLS through the STAT3 signal pathway.
Department of Rheumatology, First Affiliated Hospital of Jinan University, Guangzhou 510630, China. E-mail: renjie_shx@yahoo.com.cn.
Jie
J
Ren
Yi
Y
Zhou
Huixia
H
Wu
Taoli
T
Dai
Lihua
L
Zhu
D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D049109:Cell Proliferation; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology; D006801:Humans; D007378:Interleukins / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000166:cytology / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D013582:Synovial Fluid / Q000166:cytology; D013583:Synovial Membrane / Q000166:cytology*; D000097043:Interleukin-22
D007378:Interleukins; D050796:STAT3 Transcription Factor; D000097043:Interleukin-22; C494086:STAT3 protein, human