Type I and II IFNs differ from type III IFN in their regulation of TGF-β expression and the ERK–JNK pathway in renal fibroblasts during kidney fibrosis. (A–C) Primary renal fibroblasts from WT mice were treated for 24 h with 100 ng/ml of various IFNs subtypes (IFN-α, IFN-β, IFN-γ, or IFN-λ2) or PBS. (A and B)Isg15, Mx1, Ifit1, and Tgf-β mRNA levels were assessed by RT-qPCR (n = 6), and (C) TGF-β protein in the culture supernatants was quantified by ELISA (n = 4). (D–F) Primary skin fibroblasts from WT mice were treated for 24 h with 100 ng/ml of various IFNs subtypes (IFN-α, IFN-β, IFN-γ, or IFN-λ2) or PBS. (D and E)Isg15, Mx1, Ifit1, and Tgf-β mRNA levels were detected by RT-qPCR (n = 6), and (F) TGF-β protein in the culture supernatants was measured by ELISA (n = 4). (G–J) WT, Ifnar^–/–, and Ifngr1^−/− mice were subjected to sham or UUO surgery, and kidneys were collected on day 7. n = 6 per group. (G) Representative images and quantitative analysis of fibrotic areas with Masson’s trichrome and PSR staining (scale bars = 50 μm). (H) RT-qPCR analysis of Acta2, fibronectin, and vimentin mRNA levels in kidneys. TGF-β mRNA and protein levels in kidneys were measured by RT-qPCR (I) and western blot (J). (K and L) Primary kidney fibroblasts were treated with 100 ng/ml IFN-α (K) or IFN-β (L) for the indicated times. (K and L) Western blot analysis of phosphorylated and total ERK and JNK protein levels. Data in A–I are pooled from two independent experiments. Data in J–L are representative of three independent experiments. Data are presented as mean ± SEM. *P < 0.05, ****P < 0.0001, by two-way ANOVA with Tukey’s multiple-comparison test (A–I). ns, no significant difference. Source data are available for this figure: SourceData FS4.