Expression of the cysteine protease inhibitor cystatin C in hepatic stellate cells is upregulated during transdifferentiation

Background: Cystatin C (CysC) belongs to a group of non-glycosylated, low molecular mass cysteine protease inhibitors that inactivates members of the cathepsin family. CysC is reported to control the cleavage of membrane and extracellular matrix proteins, to regulate cell proliferation and, recently, to antagonize TGF-β binding to its cell surface receptors, in particular to type II receptor (TβRII). Up to now expression, regulation, and functional significance of CysC in cultured rat and human hepatic stellate cells (HSC) and myofibroblasts (MFB) are unknown.