Rational design and synthesis of lumican stapled peptides for promoting corneal wound healing

Purpose: Lumican is a major extracellular matrix (ECM) component in the cornea that is upregulated after injury and promotes corneal wound healing. We have recently shown that peptides designed based on the 13 C-terminal amino acids of lumican (LumC13 and LumC13C-A) are able to recapitulate the effects of lumican on promoting corneal wound healing. Herein we used computational chemistry to develop peptide mimetics derived from LumC13C-A with increased stability and halflife that are biologically active and non-toxic, thereby promoting corneal wound healing with increased pharmacological potential. Methods: Different peptides staples were rationalized using LumC13C-A sequence by computational chemistry, docked to TGF beta RI and the interface binding energies compared. Lowest scoring peptides were synthesized, and the toxicity of peptides tested using CCK8-based cell viability assay. The efficacy of the stapled peptides at promoting corneal wound healing was tested using a proliferation assay, an in vitro scratch assay using human corneal epithelial cells and an in vivo murine corneal debridement wound healing model. Results: Binding free energies were calculated using MMGBSA algorithm, and peptides LumC13C and LumC13S5 displayed superior binding to ALK5 compared to the non-stapled peptide LumC13C-A. The presence of the hydrocarbon staple in LumC13C enhances the stability of the alpha-helical conformation, thereby facilitating more optimal interactions with the ALK5 receptor. The stapled peptides do not present cytotoxic effects on human corneal epithelial cells at a 300 nM concentration. Similar to lumican and LumC13C-A, both C13C and LumC13S5 significantly promote corneal wound healing both in vitro and in vivo. Conclusions: Highly stable and non-toxic stapled peptides designed based on LumC13, significantly promote corneal wound healing. As a proof of principle, our data shows that more stable and pharmacologically relevant peptides can be designed based on endogenous peptide sequences for treating various corneal pathologies.