Optimisation of peptides that actively cross the tympanic membrane by random amino acid extension: a phage display study

Abstract

Local treatment of middle ear (ME) disease currently requires surgical penetration of the tympanic membrane (TM). We previously discovered 12-mer peptides that are actively transported across the intact TM, a process that could be used for non-invasive drug delivery into the ME. To optimise transport and provide further understanding of the peptides transport mechanism, we extended two of the candidate peptides by six additional amino acids at random, and screened the resulting 18-mers libraries on TMs of rats with active bacterial otitis media (OM) for transport efficiency using phage display. Six identified peptides were individually tested in vivo for trans-TM transport to verify the tissue specificity. Three exhibited enhanced transport compared to their parent 12-mer scaffold, with the best showing an approximately nine-fold increase. Sequence analysis revealed anchor residues and structural features associated with enhanced transport. This included the prominent display of conserved sequence motifs at the extended free ends of the predicted peptide structures.

Keywords:

• Drug delivery
• otitis media
• active transport
• peptide structure
• conserved motifs

Disclosure statement

The authors report no conflicts of interest. However, Dr. Ryan is a cofounder of Otonomy, Inc., serves as a member of the Scientific Advisory Board, and holds an equity position in the company. This relationship has been approved by the UCSD Committee on Conflict of Interest. Otonomy, Inc. played no part in the research reported here.

Additional information

Funding

Action on Hearing Loss10.13039/501100000703

National Institute on Deafness and Other Communication Disorders10.13039/100000055

Veterans Affairs San Diego Healthcare System10.13039/100009012

This work was financially supported by the TRIH initiative of Action on Hearing Loss, and by the National Institute of Health/National Institute on Deafness and Other Communication Disorders (NIH/NIDCD) under grant DC012595; and grant DC000129, and by the Veterans Affairs San Diego Healthcare System under grant BX001205.