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

Excessive transforming growth factor beta 1 (TGF-beta 1) secreted by activated hepatic stellate cells (aHSCs) aggravates liver fibrosis via over-activation of TGF-beta 1-mediated signaling pathways in a TGF-beta type I receptor (T beta RI) dependent manner. T beta RI with the C-terminal valine truncated (RIP Delta), as a novel T beta RI-mimicking peptide, is an appealing anti-fibrotic candidate by competitive binding of TGF-beta 1 to block TGF-beta 1 signal transduction. Plateletderived growth factor receptor beta (PDGF beta R) is highly expressed on the surface of aHSCs in liver fibrosis. Herein, we designed a novel RIP Delta variant Z-RIP Delta (PDGF beta R-specific affibody ZPDGF beta R fused to the N-terminus of RIP Delta) for liver fibrosis therapy, and expect to improve the anti-liver fibrosis efficacy by specifically inhibiting the TGF-beta 1 activity in aHSCs. Target peptide Z-RIP Delta was prepared in Escherichia coli by SUMO fusion system. Moreover, ZRIP Delta specifically bound to TGF-beta 1-activated aHSCs, inhibited cell proliferation and migration, and reduced the expression of fibrosis markers (alpha-SMA and FN) and TGF-beta 1 pathway-related effectors (p-Smad2/3 and p-p38) in vitro. Furthermore, Z-RIP Delta specifically targeted the fibrotic liver, alleviated the liver histopathology, mitigated the fibrosis responses, and blocked TGF-beta 1-mediated Smad and p38 MAPK cascades. More importantly, Z-RIP Delta exhibited a higher fibrotic liver-targeting capacity and stronger anti-fibrotic effects than its parent RIP Delta. Besides, Z-RIP Delta 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-RIP Delta represents a promising targeted candidate for liver fibrosis therapy.