Fig. 4

EGR1 was the key target for iguratimod to the inhibition of fibroblast function. A, B Knockdown of EGR1 inhibited fibroblast activation and ECM production. A Relative mRNA level of EGR1 in human dermal fibroblast transfected with n.t.siRNA or EGR1 siRNA. B Relative mRNA level of COL1A1, FN1, and ACTA2 in human dermal fibroblast transfected with n.t.siRNA or EGR1 siRNA and treated with or without TGFβ. N = 4 per group. C–E EGR1 overexpression neutralized the inhibition of fibroblast activation and ECM production treated with iguratimod. C Relative mRNA level of EGR1 in human dermal fibroblast transfected with pcDNA3.1or EGR1 pcDNA3.1. D Relative mRNA level of COL1A1, FN1, and ACTA2 in human dermal fibroblast transfected with pcDNA3.1or EGR1 pcDNA3.1 and treated with iguratimod or TGFβ. N = 4 per group. E Protein level of EGR1 and collagen I in human dermal fibroblast transfected with pcDNA3.1or EGR1 pcDNA3.1 and treated with iguratimod or TGFβ. The representative image and quantification were included N = 3 per group. *, 0.05 > P > 0.01; **, 0.01 > P > 0.001; ***, P < 0.001. Mann–Whitney testing was used for statistical analyses in A and C. One-way ANOVA with Bonferroni multiple comparisons test was used in B, D, and E. Data are represented as mean ± standard deviation