Figure 6.

IGFBP‐4 reduces levels of the profibrotic factor CTGF. A. IGFBP‐4 reduces basal CTGF levels. Human primary lung fibroblasts were infected with replication‐deficient adenovirus encoding IGFBP‐4 or control adenovirus for 72 hours. CTGF protein levels were assessed in cellular lysates by WB. B. IGFBP‐4 inhibits TGF‐ß induction of CTGF. Primary human lung fibroblasts were treated with vehicle control or 10 ng/mL of TGF‐ß1 for 48 hours following 24 hours infection with replication‐deficient adenovirus encoding IGFBP‐4 or control adenovirus. Cell lysates were analyzed by WB. Experiments were repeated three times with similar results. C. Silencing CTGF potentiates the antifibrotic effect of IGFBP‐4. Human primary lung fibroblasts were transfected with siRNA targeting CTGF or control siRNA for 24 hours then treated with 2 µg/mL of rhIGFBP‐4 or vehicle for 48 hours. Cell lysates were analyzed by western blot. (D) Graphical presentation of densitometry results for FN from fibroblasts of three donors treated as in (C). (E) Graphical presentation of densitometry results for Col1A1 from fibroblasts of three donors treated as in (C). *P < 0.05, **P < 0.01