Figure 1

GPI is highly expressed and secreted in RA-FLS. A, Immunohistochemistry staining of GPI and GP78 in arthritic synovial tissues from RA and OA patients (OA serum GPI: 0.1 μg/ml; RA serum GPI: 1.8 μg/ml). Original magnification × 200. B, Western blot (top) and quantitative RT-PCR analysis (bottom) of GPI level in FLS. OA (n = 8, serum GPI concentration <0.2 μg/ml), GPI (+) RA (n = 4, serum GPI concentration = 1.3 ± 0.8 μg/ml), GPI (−) RA (n = 4, serum GPI concentration <0.2 μg/ml). Friedman’s M test and SNK-q test were used for statistical analysis. C, Western blot (top) and ELISA (bottom) analysis of GPI level in the supernatant of FLS. Friedman’s M test and SNK-q test were used for statistical analysis. D, Western blot (top) and quantitative RT-PCR analysis (bottom) of the levels of secreted and cellular GPI in FLS transfected with expression plasmids and siRNAs. Data were shown as mean ± SD. P values were determined by Wilcoxon signed-rank test. (N = number of individuals, R = number of replicates; GPI, glucose 6-phosphate isomerase; gp78, glycoprotein 78;RA, rheumatoid arthritis; OA, osteoarthritis; FLS, fibroblast-like synoviocytes; NC, negative control).