title: Modified peptide antagonists of interleukin 5 exhibit extended in vivo persistence but restricted species specificity.
abstract: AF18748 is disulphide-linked homodimeric peptide with 19 amino acids in each chain that antagonises the action of the eosinophil-specific cytokine, interleukin 5 (IL-5). We have generated a set of N-terminally truncated peptides derived from AF18748 and demonstrated that the first five amino acids of the peptide do not contribute to receptor binding activity. The shortened peptide blocked IL-5-dependent adhesion of eosinophils with an IC(50)of 350 pM, and had no effect on stimulation by IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), tumour necrosis factor (TNF)-alpha or fMet-Leu-Phe. The peptides were rapidly broken down in mouse plasma through cleavage of a single chain of the dimer. However, this breakdown did not correlate with loss of biological activity, indicating that the asymmetric peptide fragment retains full receptor binding capacity. The activity of AF18748 disappeared rapidly from the blood following intravenous injection into mice. Coupling of polyethylene glycol to the N-terminus of AF18748 resulted in a moderate loss in biological potency (IC(50)30 nM), but the resulting conjugate persisted in the circulation for more than 8 h after injection. Despite its high potency at the human IL-5 receptor, AF18748 was unable to antagonise the activity of IL-5 on murine B13 cells, or on canine eosinophils, indicating that the peptide is highly specific for the human IL-5 receptor.
authors.affiliation: Department of Cell Biology, GlaxoWellcome Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2NY, UK. iju44964@glaxowellcome.co.uk
authors.forename: I J
authors.initials: IJ
authors.lastname: Uings
authors.forename: P
authors.initials: P
authors.lastname: Balasubramanian
authors.forename: P G
authors.initials: PG
authors.lastname: McLoughlin
authors.forename: Q
authors.initials: Q
authors.lastname: Yin
authors.forename: L
authors.initials: L
authors.lastname: Dash
authors.forename: A
authors.initials: A
authors.lastname: Beresford
authors.forename: S
authors.initials: S
authors.lastname: Kearney
authors.forename: R W
authors.initials: RW
authors.lastname: Barrett
authors.forename: M
authors.initials: M
authors.lastname: McKinnon
authors.forename: B P
authors.initials: BP
authors.lastname: England
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D002460:Cell Line; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004804:Eosinophils / Q000378:metabolism; D005434:Flow Cytometry; D006098:Granulocytes / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D007377:Interleukin-3 / Q000494:pharmacology; D015848:Interleukin-5 / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016177:Macrophage-1 Antigen / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000494:pharmacology; D011485:Protein Binding; D021382:Protein Sorting Signals; D018123:Receptors, Interleukin / Q000378:metabolism; D053649:Receptors, Interleukin-5; D012542:Scattering, Radiation; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D007377:Interleukin-3; D015848:Interleukin-5; D016177:Macrophage-1 Antigen; D010455:Peptides; D021382:Protein Sorting Signals; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5; D014409:Tumor Necrosis Factor-alpha; D011092:Polyethylene Glycols; D009240:N-Formylmethionine Leucyl-Phenylalanine