Thesis abstract:

Inflammation is a vital process to eliminate pathogens and kickstart injury repair, however dysregulation of this response can lead to chronic inflammation and disease. Recruitment of immune cells to sites of inflammation is orchestrated by a network of chemoattractant proteins known as chemokines and their cell-surface receptors. Given their critical role in driving inflammation, inhibition of chemokine-receptor interactions presents an emerging approach for the treatment of inflammatory disease. This strategy has natural precedence – chemokine-binding proteins are employed in the chemical arsenal of both viruses and parasitic organisms to allow for the evasion of immune detection. Recent advances in peptide display technologies have led to the development of a RaPID mRNA display platform with genetic reprogramming to discover potent cyclic peptide ligands through iterative rounds of screening against an immobilised protein target. However, therapeutic peptides with oral bioavailability, in addition to peptides that target gut chemokines, must survive proteolytic degradation in the gastrointestinal tract. This degradation can be circumvented by using non-proteinogenic D-amino acids that cannot be recognised and cleaved by proteases. In its current form, RaPID mRNA display technology is unable to discover entirely D-configured macrocycles. Fortunately, the selection process can be conducted on a synthetic mirror-image enantiomer of the protein target, and due to symmetry, the binding peptides discovered can simply be made using D-configured amino acids to inhibit the native L-chemokine. Hence, this research entails the establishment of such a ‘mirror-image mRNA display’ platform using genetic code reprogramming, for the development of potent ligands for proteins that are implicated in inflammatory diseases.