title: Identification of chicken cathelicidin-2 core elements involved in antibacterial and immunomodulatory activities.
abstract: Chicken host defense peptide cathelicidin-2 (CATH-2) is known to exert antimicrobial and immunomodulatory activities and consists of two alpha-helices connected by a hinge region. Here we report the biological properties of the separate alpha-helical segments and the importance of the proline residue in the hinge region. Substitution of proline-14 in the CATH-2 hinge region by leucine, but not by glycine, strongly reduced antibacterial and hemolytic activity. Furthermore, substitution by leucine strongly reduced the neutralization of LPS-induced cytokine production and peptide-induced monocyte chemotactic protein-1 (MCP-1) production by human peripheral blood mononuclear cells (PBMCs). This indicates that the hinge region is important for rapid penetration of the bacterial membrane as well as indirect and direct immunomodulatory activities. The highly cationic and amphipathic N-terminal segment (C1-15) exhibited very potent antibacterial activity and fast killing kinetics, while displaying low cytotoxicity towards chicken erythrocytes and PBMCs. The N-terminal and, to a lesser extent, the C-terminal helical regions potently neutralized LPS-induced release of TNFalpha, IL-6 and IL-10 by PBMCs, while IL-8 production was only moderately affected. These results indicate that core elements within mature CATH-2 can be identified that are linked to antibacterial and/or immunomodulatory activities. Further studies may lead to the development of peptide antibiotics with specific properties that can be used for prophylactic and/or therapeutic applications.
authors.affiliation: Department of Infectious Diseases and Immunology, Utrecht University, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: van Dijk
authors.forename: E Margo
authors.initials: EM
authors.lastname: Molhoek
authors.forename: Edwin J A
authors.initials: EJ
authors.lastname: Veldhuizen
authors.forename: Johanna L M Tjeerdsma-van
authors.initials: JL
authors.lastname: Bokhoven
authors.forename: Eveline
authors.initials: E
authors.lastname: Wagendorp
authors.forename: Floris
authors.initials: F
authors.lastname: Bikker
authors.forename: Henk P
authors.initials: HP
authors.lastname: Haagsman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D002470:Cell Survival; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D002645:Chickens; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects; D005260:Female; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007155:Immunologic Factors / Q000302:isolation & purification / Q000494:pharmacology*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; C111835:CCL2 protein, human; C504855:CMAP27 protein, chicken; D018932:Chemokine CCL2; D016207:Cytokines; D007155:Immunologic Factors; D008070:Lipopolysaccharides; D010446:Peptide Fragments