Gallic acid attenuates TGF-β1-stimulated collagen gel contraction via suppression of RhoA/Rho-kinase pathway in hypertrophic scar fibroblasts

Aims To examine the effect and molecular mechanism of gallic acid (GA) on transforming growth factor-β1 (TGF-β1)-stimulated hypertrophic scar fibroblast (HSF) contraction. Materials and methods A fibroblast-populated collagen lattice (FPCL) was developed to examine the effect of GA on TGF-β1-enhanced HSF contraction. The changes in crucial factors related to cell contraction including α-smooth muscle actin (α-SMA), F-actin, and the phosphorylation level of myosin light chain (MLC) were evaluated using western blot and immunostaining. The activation and expression of RhoA/ROCK after the TGF-β1 challenge and GA insult were evaluated using RhoA-G-LISA and RhoA-ELISA kit while the phosphorylation level of MYPT1 and the expression of ROCK1 and ROCK2 were examined by western blot, respectively. Key findings GA significantly suppressed TGF-β1-stimulated HSF contraction in a dose- and time-dependent manner. Moreover, the TGF-β1-enhanced α-SMA expression, F-actin formation, and MLC phosphorylation were obviously attenuated by GA. TGF-β1 significantly stimulated RhoA activation but did not alter the expression of RhoA in the HSFs. However, both the activation and expression of RhoA decreased obviously with GA pretreatment followed by TGF-β1 stimulation. Furthermore, GA inhibited ROCK activity but did not affect its expression after TGF-β1 stimulation. Significance These results suggest that GA exhibited the potential to prevent HSF contraction after TGF-β1 stimulation by down regulating the RhoA/ROCK signal cascade, followed by the inhibition of the expression of α-SMA, F-actin formation, and phosphorylation of MLC.