Discovery of Selective Cyclic d‑Sulfopeptide Ligands of the Chemokine CCL22 via Mirror-Image mRNA Display with Genetic Reprogramming

Chemokines are small proteins involved in recruiting
leukocytes
to sites of inflammation via interactions with specific cell surface
receptors. CCL22 is a chemokine known to play a critical role in inflammatory
diseases such as atopic dermatitis and asthma; inhibition of this
chemokine therefore represents an attractive therapeutic strategy.
Herein, we describe the discovery of cyclic d-sulfopeptide
inhibitors of CCL22 identified through mirror-image mRNA display with
genetic reprogramming. Chemical synthesis of mirror-image d-CCL22 enabled screening of a cyclic peptide library comprised of
all l-amino acids, with reprogramming of l-sulfotyrosine
to mimic the presence of this post-translational modification on native
chemokine receptors. Enriched macrocyclic peptides were prepared in
their mirror-image d-form and assessed for binding against
native l-CCL22. The most potent ligand, a plasma-stable d-cyclic peptide bearing four d-sulfotyrosine residues,
exhibited nanomolar affinity for CCL22, high selectivity over other
chemokines, and nanomolar inhibition of CCL22 signaling through CCR4.
This work highlights the vast potential of mirror-image mRNA display
technology for discovering proteolytically stable d-peptide
inhibitors of protein–protein interactions relevant across
a range of therapeutic indications.