Suppression of TGF-β1/SMAD pathway and extracellular matrix production in primary keloid fibroblasts by curcuminoids: its potential therapeutic use in the chemoprevention of keloid

Keloid is a fibrotic disease characterized by abnormal accumulation of extracellular matrix (ECM) in the dermis. It is a late spreading skin overgrowth and may be considered a plastic surgeon’s nightmare. In nature, curcuminoid is composed of curcumin, demethoxycurcumin (DMC) and bisdemethoxycurcumin (bDMC). Curcuminoids have been found to inhibit fibrosis. However, their role in the synthesis of ECM in the keloid fibroblasts (KFs) has remained unclear. In this series of studies, a total of seven primary KFs cultures were used as the KFs model for investigating the inhibitory effect of curcuminoids on the expression of ECM and TGF-β1. A sensitive and reproducible HPLC method was developed to provide a quantitative analysis on the cellular uptake of curcuminoids onto the KF cells. The level of ECM in the primary KFs was elevated. The elevation of ECM and TGF-β1/p-SMAD-2 level was substantially blocked by the cellular uptake of curcumin in a dose-dependent manner in all the seven primary KFs. The results have led to the conclusion that the excessive production of ECM in the KF cells could be blocked and/or rapidly decreased by curcumin.