Figure 1.

YAP, SNAIL and CTGF are upregulated in hyperplastic rheumatoid arthritis synovium. (A) Immunohistochemical detection of YAP, SNAIL and CTGF in quiescent and hyperplastic areas of human RA synovium (YAP n=7, SNAIL n=7, and CTGF n=6). Haematoxylin counterstain is shown in blue. Scale bars: 20 µm. For isotype negative control stainings, see online supplemental figure 10a–c. Graphs indicate protein expression in quiescent (Q) and hyperplastic (H) synovium based on immunohistochemistry (IHC) staining intensity, with lines and error bars indicating mean±SD (n=6–7). P values indicate statistical significance using an unpaired two-tailed t-test. (B) Expression of YAP (magenta), the SF marker CD55 (cyan) and the macrophage marker CD68 (yellow) in human RA synovium (n=4). DAPI (4′,6-diamidino-2-phenylindole) nuclear counterstain is shown in blue. The same image is shown three times with different channels overlaid, for clarity. Scale bars: 20 µm. For isotype negative control stainings, see online supplemental figure 10d. (C) Correlation between YAP gene expression and expression of SNAIL, CTGF or GP130 in RA synovial biopsies (n=10) as determined by qRT-PCR. P values indicate results of Pearson’s correlation test and R² values the square of the correlation coefficient. CTGF, connective tissue growth factor; RA, rheumatoid arthritis; SF, synovial fibroblast; YAP, Yes-associated protein.