title: Identification and Characterization of a Novel IL-4 Receptor α Chain (IL-4Rα) Antagonist to Inhibit IL-4 Signalling.
abstract: OBJECTIVE
  In recent times, allergy has become a financial, physical and psychological burden to the society as a whole. In allergic cascades, cytokine IL-4 binds to IL-4 receptor (IL-4R), consequently producing allergen-specific IgE antibodies by B cells. In addition, among other functions, IL-4 is also responsible for B and T cell proliferation and differentiation. Hence, characterization of novel antagonists that inhibit IL-4 signalling forms the overall aim of this study.
  
  
  METHODS
  Phage display was used to screen a random 12-mer synthetic peptide library with a human IL-4Rα to identify peptide candidates. Once identified, the peptides were commercially synthesized and used for in vitro immunoassays.
  
  
  RESULTS
  We have successfully used phage display to identify M13 phage clones that demonstrated specific binding to IL-4Rα. The peptide N1 was synthesized for use in ELISA, demonstrating significant binding to IL-4Rα and inhibiting interaction with cytokine IL-4. Furthermore, the peptide was tested in a transfected HEK-Blue IL-4 reporter cell line model, which produces alkaline phosphatase (AP). QUANTI-Blue, a substrate, breaks down in the presence of AP producing a blue coloration. Using this colorimetric analysis, >50% inhibition of IL-4 signalling was achieved.
  
  
  CONCLUSIONS
  We have successfully identified and characterised a synthetic peptide antagonist against IL-4Rα, which effectively inhibits IL-4 interaction with the IL-4Rα in vitro. Since IL-4 interaction with IL-4Rα is a common pathway for many allergies, a prophylactic treatment can be devised by inhibiting this interaction for future treatment of allergies.
authors.affiliation: NeuroAllergy Research Laboratory (NARL), School of Life and Environmental Sciences, Faculty of Science, Engineering and Built Environment, Deakin University, Geelong, Victoria, Australia.
authors.forename: Nayyar
authors.initials: N
authors.lastname: Ahmed
authors.forename: Pathum
authors.initials: P
authors.lastname: Dhanapala
authors.forename: Cenk
authors.initials: C
authors.lastname: Suphioglu
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry; D018926:Anti-Allergic Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D001681:Biological Assay; D002460:Cell Line; D003124:Colorimetry; D015870:Gene Expression; D057809:HEK293 Cells; D006801:Humans; D015847:Interleukin-4 / Q000235:genetics / Q000378:metabolism*; D053662:Interleukin-4 Receptor alpha Subunit / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D019151:Peptide Library; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D018926:Anti-Allergic Agents; C508598:IL4 protein, human; C504000:IL4R protein, human; D053662:Interleukin-4 Receptor alpha Subunit; D019151:Peptide Library; D010455:Peptides; D020033:Protein Isoforms; D015847:Interleukin-4; D000469:Alkaline Phosphatase