Targeting delivery of a novel TGF-β type I receptor-mimicking peptide to activated hepatic stellate cells for liver fibrosis therapy via inhibiting the TGF-β1/Smad and p38 MAPK signaling pathways

Abstract

Excessive transforming growth factor β1 (TGF-β1) secreted by activated hepatic stellate cells (aHSCs) aggravates liver fibrosis via over-activation of TGF-β1-mediated signaling pathways in a TGF-β type I receptor (TβRI) dependent manner. TβRI with the C-terminal valine truncated (RIPΔ), as a novel TβRI-mimicking peptide, is an appealing anti-fibrotic candidate by competitive binding of TGF-β1 to block TGF-β1 signal transduction. Platelet-derived growth factor receptor β (PDGFβR) is highly expressed on the surface of aHSCs in liver fibrosis. Herein, we designed a novel RIPΔ variant Z-RIPΔ (PDGFβR-specific affibody Z_PDGFβR fused to the N-terminus of RIPΔ) for liver fibrosis therapy, and expect to improve the anti-liver fibrosis efficacy by specifically inhibiting the TGF-β1 activity in aHSCs. Target peptide Z-RIPΔ was prepared in Escherichia coli by SUMO fusion system. Moreover, Z-RIPΔ specifically bound to TGF-β1-activated aHSCs, inhibited cell proliferation and migration, and reduced the expression of fibrosis markers (α-SMA and FN) and TGF-β1 pathway-related effectors (p-Smad2/3 and p-p38) in vitro. Furthermore, Z-RIPΔ specifically targeted the fibrotic liver, alleviated the liver histopathology, mitigated the fibrosis responses, and blocked TGF-β1-mediated Smad and p38 MAPK cascades. More importantly, Z-RIPΔ exhibited a higher fibrotic liver-targeting capacity and stronger anti-fibrotic effects than its parent RIPΔ. Besides, Z-RIPΔ showed no obvious toxicity effects in treating both an in vitro cell model and an in vivo mouse model of liver fibrosis. In conclusion, Z-RIPΔ represents a promising targeted candidate for liver fibrosis therapy.

Keywords: Liver fibrosis; Transforming growth factor β type I receptor; Transforming growth factor β1.