title: Structure-activity studies and therapeutic potential of host defense peptides of human thrombin.
abstract: Peptides of the C-terminal region of human thrombin are released upon proteolysis and identified in human wounds. In this study, we wanted to investigate minimal determinants, as well as structural features, governing the antimicrobial and immunomodulating activity of this peptide region. Sequential amino acid deletions of the peptide GKYGFYTHVFRLKKWIQKVIDQFGE (GKY25), as well as substitutions at strategic and structurally relevant positions, were followed by analyses of antimicrobial activity against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, the Gram-positive bacterium Staphylococcus aureus, and the fungus Candida albicans. Furthermore, peptide effects on lipopolysaccharide (LPS)-, lipoteichoic acid-, or zymosan-induced macrophage activation were studied. The thrombin-derived peptides displayed length- and sequence-dependent antimicrobial as well as immunomodulating effects. A peptide length of at least 20 amino acids was required for effective anti-inflammatory effects in macrophage models, as well as optimal antimicrobial activity as judged by MIC assays. However, shorter (>12 amino acids) variants also displayed significant antimicrobial effects. A central K14 residue was important for optimal antimicrobial activity. Finally, one peptide variant, GKYGFYTHVFRLKKWIQKVI (GKY20) exhibiting improved selectivity, i.e., low toxicity and a preserved antimicrobial as well as anti-inflammatory effect, showed efficiency in mouse models of LPS shock and P. aeruginosa sepsis. The work defines structure-activity relationships of C-terminal host defense peptides of thrombin and delineates a strategy for selecting peptide epitopes of therapeutic interest.
authors.affiliation: Division of Dermatology and Venereology, Department of Clinical Sciences, Lund University, Biomedical Center, Tornavägen 10, SE-22184 Lund, Sweden.
authors.forename: Gopinath
authors.initials: G
authors.lastname: Kasetty
authors.forename: Praveen
authors.initials: P
authors.lastname: Papareddy
authors.forename: Martina
authors.initials: M
authors.lastname: Kalle
authors.forename: Victoria
authors.initials: V
authors.lastname: Rydengård
authors.forename: Matthias
authors.initials: M
authors.lastname: Mörgelin
authors.forename: Barbara
authors.initials: B
authors.lastname: Albiger
authors.forename: Martin
authors.initials: M
authors.lastname: Malmsten
authors.forename: Artur
authors.initials: A
authors.lastname: Schmidtchen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology; D054804:Cathelicidins
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; C000600278:GKY25 peptide; D010446:Peptide Fragments; D013917:Thrombin; D054804:Cathelicidins