(642a) De Novo Design of Skin-Penetrating Peptides for Enhanced Transdermal Delivery of Peptide Drugs

Skin-penetrating peptides (SPPs) are attracting increasing attention as a noninvasive strategy for transdermal delivery of therapeutics. Recent work has demonstrated their potential for dermal delivery, and experimental as well as theoretical studies have elucidated their mechanism of action. However, discovery of such peptides is largely driven by experimental screening of large libraries rather than theoretical or computational designs. Recent mechanistic studies have shown that SPPs must possess affinity for both keratin in skin and the drug of interest to be effective enhancers. Based on this finding, we computationally generated and screened virtual libraries of disulfide-bonded, cyclic peptides against keratin and Cyclosporine A (CsA) to identify SPPs capable of enhancing transdermal delivery of CsA. The sequential screening procedure was performed using the docking software HADDOCK and returned a list of sequences that were tested in vitro to validate their ability to bind CsA and enhance its transdermal permeation. The selected sequences were experimentally tested and were found to bind keratin and CsA, as determined by mass spectrometry and affinity chromatography, as well as to enhance CsA transport across the skin. The leading heptameric sequences were tested and yielded CsA permeation on par with previously discovered SPP (SPACE). An octameric peptide yielded significantly higher delivery of CsA compared to heptameric SPPs. Further, the safety profile of the selected sequences was validated by incubation with skin keratinocytes. This method represents an effective procedure for the de novo design of skin-penetrating peptides for the delivery of desired therapeutic or cosmetic agents.