Antifibrotic action of Cu/Zn SOD is mediated by TGF-beta 1 repression and phenotypic reversion of myofibroblasts

Skin fibrosis is characterized by the proliferation and accumulation of act ivated fibroblasts called myofibroblasts. They exhibit specific cytoskeleta l differentiation, overexpress the fibrogenic cytokine TGF-beta1, synthesiz e excess extracellular matrix compounds and exhibit a depleted antioxidant metabolism. Recently, SOD was successfully used as an antifibrotic agent in vivo, thus challenging the postulate of established fibrosis irreversibili ty. We postulated that myofibroblasts could be a direct target for this the rapeutic effect. To test this hypothesis, we used three-dimensional co-cult ure models of skin, in which specific phenotypes of normal fibroblasts vers us myofibroblasts are retained. These 3-D models were treated with liposoma l and carrier-free Cu/Zn SOD, and examined for their effects on cell number , cell death, and phenotypic differentiation. The results show that SOD did not induce myofibroblast cell death, whereas it significantly reduced TGF- beta1 expression, thus demonstrating that SOD might be proposed as a potent antagonist of this major fibrogenic growth factor. We also found that SOD significantly lowered the levels of the myofibroblast marker alpha -sm acti n, of beta -actin, and of the extracellular matrix components alpha1(1) col lagen and tenascin-C. In conclusion, our results suggest that SOD antifibro tic action occurred in vitro through the reversion of myofibroblasts into n ormal fibroblasts. (C) 2000 Elsevier Science Inc.