Figure 5.

Interleukin-17 (IL-17) increased expression of Toll-like receptor 3 (TLR3) via the phospho-signal transducer and activator of transcription 3 (STAT3) pathway in rheumatoid arthritis fibroblast-like synoviocytes (RA FLS). (a) The STAT3 pathway was blocked with S3I-201 (10 μm or 50 μm), and RA (n = 4) and osteoarthritis (OA) (n = 4) FLS were stimulated with recombinant human (rh) IL-17 (1 ng/ml). The FLS were pre-treated for 1 hr with S3I-201 and then were cultured with rhIL-17 for 24 hr, and the mRNA levels of TLR2, TLR3 and TLR4 were measured by RT-PCR. The expressions of TLR2, TLR3 and TLR4, relative to β-actin were measured. (b) Immunohistochemical staining for TLR3, STAT3 and phospho-STAT3-Ser727 were performed on sections of synovium from RA and OA patients. The sections were stained with specific antibodies to anti-human-TLR3, -STAT3, and -phospho-STAT3. The brown colour shows the positive cells. All tissues were counterstained with haematoxylin (original magnification × 400). Data are expressed as mean ± SD of four different patients. **P < 0·01 compared with IL-17 stimulation.