Calycosin Inhibits Intestinal Fibrosis on CCD-18Co Cells via Modulating Transforming Growth Factor-β/Smad Signaling Pathway

Intestinal fibrosis is the major complication of Crohn's disease (CD). There are no other good treatments for CD except surgery and remains a refractory disease. Calycosin (CA), the active component of astragalus membranaceus, has been reported the potential effect on lung fibrosis and renal fibrosis. In this study, we aim to explore the effect of CA on intestinal fibrosis in vitro and the possible signal pathway.The antifibrotic effect of CA is investigated in human intestinal fibroblasts (CCD-18Co) cells induced by transforming growth factor-β1 (TGF-β1). MTT method was used to screen the concentration of CA. Real-time polymerase chain reaction and western blot analysis were used to evaluate the expression of α-smooth muscle actin (α-SMA), collagen I, and TGF-β/Smad pathway.The results showed that the concentration of CA was 12.5, 25, 50 μmol/L. CA could inhibit the expression of α-SMA and collagen I. In addition, CA regulated the expression of TGF-β/Smad signaling pathway.This study demonstrated that CA could inhibit the activation of CCD-18Co cells and reduce the expression of extracellular matrix. Our study highlighted that CA-inhibited TGF-β/Smad pathway through inhibiting the expression of p-Smad2, p-Smad3, Smad4, and TGF-β1 and raised the Smad7 expression. Therefore, CA might inhibit intestinal fibrosis by inhibiting the TGF-β/Smad pathway.