Fig. 3

Priming of fibroblasts by pro-inflammatory cytokines is site-specific and gene-specific, but not stimulus-specific. a Following the protocol described in Fig. 1, primary human dermal fibroblasts were treated for 24 h with vehicle, TNFα or IL-1α, washed and rested for 24 h, then treated again with vehicle, TNFα or IL-1α for 24 h. Expression of IL-6 protein was measured after the first and second treatments. Mean ± SEM, n = 5. n.s. not significant as determined by the Mann-Whitney U test. b Adapting the protocol described in Fig. 1, BJ fibroblasts were treated for 24 h with TNFα, washed and rested for 24 h then treated with TNFα or IL-1α for 24 h (left graph); or treated for 24 h with IL-1α, washed and rested for 24 h, then treated with IL-1α or TNFα (right graph). IL-6 expression in response to the second stimulus is represented relative to the response to the same first stimulus. Mean fold change in IL-6 expression between the second and first response ± SEM, n = 6. *p < 0.05 (Wilcoxon matched pair signed rank test). c Fibroblast-like synoviocytes (FLS) were treated with TNFα for 24 h, washed and rested for 24 h, then re-stimulated with TNFα. Secreted IL-6, CCL5 and IL-8 were measured after the first and second stimulations, and fold changes in expression calculated. Mean fold change ± SEM, n = 5–8. **p < 0.01; n.s. not statistically significant (Wilcoxon matched pair signed rank test)