Enhancement of the inhibitory effect of an IL-15 antagonist peptide by alanine scanning

• Published in: Journal of peptide science Vol. 18; no. 1; pp. 25 - 29
• Main Authors: Savio, Alicia Santos, Acosta, Osvaldo Reyes, Pérez, Haydee Gerónimo, Álvarez, Yunier Rodríguez, Chico, Araceli, Pérez, Hilda Garay, Ojeda, Miriam Ojeda, Aguero, Celia Aurora Arrieta, Estévez, Miguel, Nieto, Gerardo Guillen
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.01.2012
• Subjects: Alanine - chemistry; Alanine - metabolism; Amino Acid Sequence; antagonist; Arthritis, Rheumatoid - drug therapy; Arthritis, Rheumatoid - immunology; Arthritis, Rheumatoid - metabolism; Arthritis, Rheumatoid - pathology; Cell Line; Chromatography, High Pressure Liquid; cytokine; Enzyme-Linked Immunosorbent Assay; Humans; IL-15; Inhibitory Concentration 50; Interleukin-15 - chemistry; Interleukin-15 - immunology; Interleukin-15 Receptor alpha Subunit - antagonists & inhibitors; Interleukin-15 Receptor alpha Subunit - immunology; Lysine - chemistry; Lysine - metabolism; Molecular Sequence Data; peptide; Peptides - chemical synthesis; Peptides - pharmacology; Protein Binding; receptor alpha; Structure-Activity Relationship; Synovial Fluid - cytology; Synovial Fluid - drug effects; Synovial Fluid - immunology; T-Lymphocytes - drug effects; T-Lymphocytes - immunology; Threonine - chemistry; Threonine - metabolism; Tumor Necrosis Factor-alpha - antagonists & inhibitors; Tumor Necrosis Factor-alpha - immunology; Tumor Necrosis Factor-alpha - secretion
• ISSN: 1075-2617; 1099-1387
• DOI: 10.1002/psc.1411

IL‐15 is a proinflammatory cytokine that acts early in the inflammatory response and has been associated with several autoimmune diseases including rheumatoid arthritis, where it had been proposed as a therapeutic target. We recently reported an IL‐15 antagonist peptide corresponding to sequence 36–45 of IL‐15 (KVTAMKCFLL) named P8, which specifically binds to IL‐15Rα and inhibits IL‐15 biological activity with a half maximal inhibitory concentration (IC50) of 130 µ m in CTLL‐2 proliferation assay. In order to improve binding of peptide P8 to the receptor IL‐15Rα, we used an Ala scan strategy to study contribution of each individual amino acid to the peptide's antagonist effect. Here, we found that Phe and Cys are important for peptide binding to IL‐15Rα. We also investigated other single site mutations and replaced the second Lys in the sequence by the polar non‐charged amino acid threonine. The resulting peptide [K6T]P8 exhibited a higher activity than P8 with an IC50 of 24 µm. We also found that this peptide was more active than peptide P8 in the inhibition of TNFα secretion by synovial cells from rheumatoid arthritis patients. The peptide [K6T]P8 described in this work is a new type of IL‐15 antagonist and constitutes a potential therapeutic agent for rheumatoid arthritis. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd. IL‐15 is a potential target in rheumatoid arthritis. We had identified a peptide (P8) which inhibits binding of IL‐15 to IL‐15Rα and affects IL‐15 biological activity. Here, we studied P8 peptide analogs based on Ala scanning and other punctual mutations. As a result, we found a more active peptide inhibiting both IL‐15 biological activity and TNFα secretion by synovial cells