In the present study, the effect of asiatic acid (AA) on SSc-associated pulmonary fibrosis (PF) and its association with the transforming growth factor-β1 (TGF-β1)/Smad2/3 signaling pathway were evaluated.
We observed critical changes in the scleroderma epidermis; showing significantly increased nuclear translocation of phosphorylated Smad2/3, consistent with active TGFβ signaling in SSc keratinocytes.
Furthermore, we found the c-met promoter contains a putative binding site for Smads, and the binding activity of Smad2/3 to the c-met promoter was constitutively up-regulated in SSc fibroblasts as well as in normal fibroblasts treated with exogenous TGF-β1.
TGF-beta signaling events, including phosphorylation of Smad2 and -3, and transcription of the PAI-1 gene are increased in scleroderma fibroblasts, relative to normal fibroblasts.