Fig. 1

Primary human OA chondrocytes (a) and human T/C28a2 chondrocyte cell line (b) express TRPA1 mRNA and its expression is enhanced by IL-1 in a time-dependent manner. Cultures of primary human OA chondrocytes (a) and human T/C28a2 chondrocytes (b) were stimulated with IL-1β (100 pg/ml) for 0–96 h and 0–24 h, respectively, and thereafter total RNA was extracted. TRPA1 mRNA levels were measured by qRT-PCR, and the results were normalized against GAPDH mRNA. The mRNA levels are expressed as arbitrary units with the levels measured at 24 h (a; primary OA chondrocytes) or 6 h (b; T/C28a2 chondrocytes) set as 100 %; and the values at the other time points are related to those values. Primary chondrocyte samples were obtained from three to five different donors and the experiments were carried out in duplicate. Human T/C28a2 chondrocyte experiments were carried out in quadruplicate. Results are expressed as mean + SEM. One-way ANOVA followed by Dunnett’s post-test was used in the statistical analysis; ^**indicates p < 0.01 compared to the control (0 h) sample. OA osteoarthritis, TRPA1 transient receptor potential ankyrin 1