Fig. 4

Interleukin 6 (IL-6) mRNA expression under pressure and MTX treatment. A IL-6 mRNA expression was increased under pressure (n ≥ 15, **** p < 0.0001, unpaired t-test) B IL-6 mRNA expression was not influenced by MTX treatment (1 µg/ml) (n ≥ 12, ns, one-way ANOVA). IL-6 mRNA expression was increased in MTX-treated fibroblasts under pressure to the same extent as in fibroblasts under mechanical compression without MTX (n ≥ 9, **** p < 0.0001, one-way ANOVA) C Mechanical stress increased IL-6 mRNA expression over time in mechanically compressed fibroblasts without and with MTX treatment (n = 3, * p < 0.05-** p < 0.01, one-way ANOVA). D IL-6 mRNA expression did not increase further inr mechanically compressed fibroblasts treated with higher concentrations of MTX (5 µg/ml). The values are presented as the mean ± SEM. For gene expression analysis, the ΔΔCtq method was used [36]. As a housekeeping gene, RPL22 was used because it works quite well for compression studies [11, 37]