title: Enhancement of the inhibitory effect of an IL-15 antagonist peptide by alanine scanning.
abstract: 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.
authors: Pharmaceutical Division, Center for Genetic Engineering and Biotechnology, CP, 10600, Havana, Cuba. alicia.santos@cigb.edu.cu
authors: Alicia Santos
authors: AS
authors: Savio
authors: Osvaldo Reyes
authors: OR
authors: Acosta
authors: Haydee Gerónimo
authors: HG
authors: Pérez
authors: Yunier Rodríguez
authors: YR
authors: Alvarez
authors: Araceli
authors: A
authors: Chico
authors: Hilda Garay
authors: HG
authors: Pérez
authors: Miriam Ojeda
authors: MO
authors: Ojeda
authors: Celia Aurora Arrieta
authors: CA
authors: Aguero
authors: Miguel
authors: M
authors: Estévez
authors: Gerardo Guillen
authors: GG
authors: Nieto
mesh_terms: D000409:Alanine / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D020128:Inhibitory Concentration 50; D019409:Interleukin-15 / Q000737:chemistry* / Q000276:immunology; D053720:Interleukin-15 Receptor alpha Subunit / Q000037:antagonists & inhibitors* / Q000276:immunology; D008239:Lysine / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology; D011485:Protein Binding; D013329:Structure-Activity Relationship; D013582:Synovial Fluid / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D013912:Threonine / Q000737:chemistry / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism
chemical_list: D019409:Interleukin-15; D053720:Interleukin-15 Receptor alpha Subunit; D010455:Peptides; D014409:Tumor Necrosis Factor-alpha; D013912:Threonine; D008239:Lysine; D000409:Alanine