Figure 4

Cross-regulation of IFNα and TGFβ in dermal fibroblasts. (A) Healthy control dermal fibroblasts were cultured in 10 ng/mL TGFβ for 72 hours to induce myofibroblast differentiation in vitro. After 72 hours, cultures were washed and subsequently stimulated with 50 ng/mL IFN for 24 hours. Total RNA was analyzed for TLR3 by qRT-PCR assay. Preincubation with TGFβ resulted in a greater induction of TLR3 by IFN compared with fibroblasts preincubated in 0.1% BSA (n = 7; P = 0.02). (B) Dermal fibroblasts were incubated with 50 ng/mL IFN, 10 ng/mL TGF-β or both cytokines for 24 hours. Total RNA was analyzed for TLR3, connective tissue growth factor (CTGF), and collagen type I, α₁ (COL1A1) expression by qRT-PCR assay. Coincubation of fibroblasts with IFN and TGF-β did not alter the expression of TLR3 compared with IFN alone. IFN did not alter TGF-β-induced CTGF expression but did slightly reduce COL1A1 expression in SSc dermal fibroblasts. n = 7, *P < 0.05, n.s. = not significant (Wilcoxon signed-rank test).