Screening of Interleukin-12/interleukin-23 p40 Inducers in Rheumatoid Synovial Fluids by Fluorescence Reporter Mouse System / 체질인류학회지

ABSTRACT

Although rheumatoid arthritis has been known to be a common autoimmune disease characterized by chronic inflammation mainly evident in diarthrodial joints, its pathogenesis remains to be clarified. In the present study, to investigate the pathogenic signaling system taken place in the rheumatoid joints, we assessed whether synovial fluid obtained from patients with rheumatoid arthritis contains inducers for proinflammatory cytokines such as interleukin (IL)-12 and IL-23. Peritoneal macrophages isolated from IL-12/IL-23 p40-YFP reporter mice were stimulated with synovial fluid, followed by flow cytometry to screen CD11b+ and YFP-expressing cells, reflective of IL-12/IL-23 p40-producing macrophages. The expression levels of Toll-like receptor (TLR)-2 and -4, which have a potential to mediate IL-12/IL- 23 p40 induction, were determined in synovial cells obtained from a patient with rheumatoid arthritis by RT-PCR analyses. One out of 10 synovial fluid from rheumatoid arthritis patients induced IL-12/IL-23 p40 expression, while all of 10 synovial fluid from osteoarthritis patients did not. Synoviocytes constitutively expressed Toll-like receptor (TLR)-2 and -4 which are candidate receptors for IL-12/IL-23 inducers. Upon LPS stimulation, the levels of TLR-2 and -4 were downregulated and upregulated, respectively. Taken together, these results suggest that some patients with rheumatoid arthritis elicit synovitis through TLR-2- and -4-mediated induction of proinflammatory cytokines IL-12 and IL-23.