Effect of NK-22 cells in the synovial fluid of patients with rheumatoid arthritis on the proliferation of fibroblast-like synoviocytes and its possible mechanism / 南方医科大学学报

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the effect of NK-22 cells isolated from the synovial fluid (SF) of patients with rheumatoid arthritis (RA) on the proliferation of fibroblast-like synoviocytes and explore its possible mechanism.</p><p><b>METHODS</b>The proportions of NK-22 cells in the peripheral blood (PB) and the SF of 20 RA patients and 20 healthy individuals were determined by flow cytometry. NK-22 cells in the SF sorted by flow cytometry were cultured for two weeks followed by a 4-h stimulation with 20 ng/ml phorbol 12-myristate 13-acetate and 0.5 µ mol/L ionomycin. The culture supernatant of NK-22 cells was then harvested, in which the levels of IL-22 and TNF-α were measured by ELISA. The fibroblast-like synoviocytes were exposed to the culture supernatant for 24, 48, 72, and 96 h, and the changes in the cell proliferation were detected by MTT assay.</p><p><b>RESULTS</b>RA patients showed a significantly greater proportion of NK-22 cells in both the SF and PB than the normal control subjects (P<0.05). NK-22 cells sorted by flow cytometry reached a purity exceeding 90%, and the levels of IL-22 and TNF-α in the culture supernatant of NK-22 cells cultured for two weeks were 941.16 pg/ml and 368.1 pg/ml, respectively. The culture supernatant of NK-22 cells caused a rapid proliferation of the fibroblast-like synoviocytes at 24, 48, 72, and 96 h after the exposure.</p><p><b>CONCLUSION</b>NK-22 cells in the SF of RA patients can promote the proliferation of fibroblast-like synoviocytes possibly due to the capacity of NK-22 cells to produce IL-22 and TNF-α.</p>