Targeted truncated TGF-ß receptor type II delivery to fibrotic liver by PDGFß receptor-binding peptide modification for improving the anti-fibrotic activity against hepatic fibrosis in vitro and in vivo.

Truncated transforming growth factor-ß receptor type II (tTßRII) is a promising anti-fibrotic candidate because it attenuates excessive transforming growth factor-ß1 (TGF-ß1) and then blocks TGF-ß1 activity in hepatic fibrosis. However, its use has been greatly limited due to the fact that it is expensive to chemically synthesize and it does not specifically target to the lesion site. In this study, we describe that platelet-derived growth factor ß receptor (PDGFßR)-binding peptide BiPPB modified tTßRII (BiPPB-tTßRII) was prepared from the cleavage of SUMO-BiPPB-tTßRII by digestion with SUMO-specific protease. Moreover, compared to the unmodified tTßRII, the target protein BiPPB-tTßRII not only highly specific targeted activated hepatic stellate cells (HSCs) and fibrotic liver tissue, but also significantly inhibited the protein levels of fibrosis-related genes in TGF-ß1-induced HSC-T6 cells and CCl4-induced liver fibrosis in mice. Furthermore, BiPPB-tTßRII markedly ameliorated liver morphology, fibrotic responses and the damage of liver function in fibrosis animal. More importantly, BiPPB-tTßRII showed a much lesser extent in binding to quiescent HSCs and non-fibrotic liver tissue. Taken together, our results suggested that the target protein BiPPB-tTßRII, with its high specific fibrotic liver-targeting potential and its improved anti-fibrotic activity in liver fibrosis, may be a potential therapeutic agent for liver fibrosis.

Preparation and evaluation of anti-renal fibrosis activity of novel truncated TGF-ß receptor type II.

Production of excessive transforming growth factor-beta 1 (TGF-ß1) with elevated TGF-ß1 activity has been implicated in renal fibrosis via renal epithelial cells activation and collagen deposition. As such, attenuating the binding of TGF-ß1 to its receptor TGF-beta receptor type II (TGF-ßRII) in TGF-ß1-dependent signaling is an attractive target for the control of renal fibrosis. Here, we verified the interaction between novel truncated human TGF-ßRII (thTßRII, Thr23-Gln166) and TGF-ß1, prepared thTßRII in Escherichia coli, and assessed the effects of thTßRII on TGF-ß1-induced human kidney epithelial cells (HK-2) and unilateral ureteral obstruction (UUO) model of renal fibrosis. Our data showed that thTßRII accounted for up to 20% of the total protein and 40% of the inclusion bodies of whole cell lysates under the optimal conditions (0.8 mM IPTG and 25°C for 6 H). Most of the expressed protein in inclusion body was refolded by dialysis refolding procedures and purified by Ni2+ -IDA affinity chromatography. Furthermore, thTßRII decreased type I collagen and α-smooth muscle actin protein expression in TGF-ß1-induced HK-2 cells, and ameliorated kidney morphology and fibrotic responses in fibrosis animal. These findings indicate that thTßRII holds great promise for developing new treatments for renal fibrosis.