COA-Cl prevented TGF-β1-induced CTGF expression by Akt dephosphorylation in normal human dermal fibroblasts, and it attenuated skin fibrosis in mice models of systemic sclerosis.

BACKGROUND

Systemic sclerosis (SSc) is characterized by fibrosis of the skin and internal organs. Although transforming growth factor (TGF)-β1-induced connective tissue growth factor (CTGF/CCN2) expression has been presented in SSc fibrosis, the therapeutic potential of targeting CTGF in SSc has not been fully explored. COA-Cl is a novel nucleic acid analog, which is reported to have pleiotropic beneficial biologic effects.

OBJECTIVE

We examine the effects of COA-Cl on TGF-β1-induced CTGF expression in normal human dermal fibroblast (NHDF). We also examined the effects of COA-Cl on CTGF expression in a mouse SSc model of angiotensin II (Ang II)-induced skin fibrosis.

METHODS

NHDF was cultured for in vitro experiments. For in vivo experiments, C57BL/6J mice were treated with Ang II for 14 days by subcutaneous osmotic pump. Quantitative real-time polymerase chain reaction, western blot analysis, immunohistochemical staining and immunofluorescence staining were performed to examine the expression levels of CTGF and phosphorylation levels of Smad2/3, ERK1/2 and Akt.

RESULTS

COA-Cl attenuated the TGF-β1-induced expression of both CTGF mRNA and protein in NHDF. Although COA-Cl did not alter the TGF-β1-induced phosphorylation of Smad2/3 or ERK1/2, it reduced the TGF-β1-induced phosphorylation levels of Akt in NHDF. Notably, COA-Cl dephosphorylated the Akt of lysates of TGF-β1-treated NHDF. COA-Cl reduced the levels of CTGF mRNA, CTGF protein, dermal thickness, collagen content and Akt phosphorylation in the skin of mice SSc model.

CONCLUSION

These results imply that the inhibition of TGF-β1-induced CTGF expression by COA-Cl may be a therapeutic approach for SSc.