Quercetin, Kaempferol and Capsaicin Counteract the TGF-β1-Induced Upregulation of αSMA and Collagen in Myoblasts
Iris Cuijpers, Mireille M.J.P.E. Sthijns, Veerle A. R. van den Bogart, Joey Katsburg, Cliff F. M. Leenders, Freddy J. Troost
Abstract
In fibrotic skeletal muscles, excessive extracellular matrix (ECM) deposition is a result of increased activation and decreased apoptosis of myofibroblasts. The aim of this study is to investigate whether treatment with quercetin, kaempferol or capsaicin can reduce the transforming growth factor-beta 1 (TGF-β1)-induced myofibroblast differentiation and fibrotic ECM expression in differentiated C2C12 cells. Two-day-differentiated C2C12 cells were treated with TGF-β1 for 48 h to induce myofibroblast differentiation. Twenty-four hours before (pre-treatment) and for forty-eight hours with (co-treatment) TGF-β1 treatment, cells were exposed to quercetin (25, 50 µM), kaempferol (10, 25, 50 µM) or capsaicin (25, 50 µM). The immunofluorescence intensity of alpha smooth muscle actin (αSMA) and collagen type I/III gene expression were assessed as myofibroblast markers. MyoD immunofluorescence intensity was measured as a myogenic marker. Co-treatment of TGF-β1 with the phytochemicals was most effective, resulting in a decreased number of αSMA-positive cells (all three compounds), decreased collagen type I (kaempferol, capsaicin) and type III (kaempferol) gene expression, and increased MyoD (kaempferol, capsaicin) protein expression compared to TGF-β1 treatment. This study demonstrates that treatment with quercetin, kaempferol or capsaicin can reduce myofibroblast markers. This suggests a possible anti-fibrotic effect of the phytochemicals in skeletal muscle.