The human CXC chemokine granulocyte chemotactic protein 2 (GCP-2)/CXCL6 possesses membrane-disrupting properties and is antibacterial

Research output: Contribution to journalArticle

Abstract

Granulocyte chemotactic protein 2 (GCP-2)/CXCL6 is a CXC chemokine expressed by macrophages and epithelial and mesenchymal cells during inflammation. Through binding and activation of its receptors (CXCR1 and CXCR2), it exerts neutrophil-activating and angiogenic activities. Here we show that GCP-2/CXCL6 itself is antibacterial. Antibacterial activity against gram-positive and gram-negative pathogenic bacteria of relevance to mucosal infections was seen at submicromolar concentrations (minimal bactericidal concentration at which 50% of strains tested were killed, 0.063 +/- 0.01 to 0.37 +/- 0.03 muM). In killed bacteria, GCP-2/CXCL6 associated with bacterial surfaces, which showed membrane disruption and leakage. A structural prediction indicated the presence of three antiparallel NH(2)-terminal beta-sheets and a short amphipathic COOH-terminal alpha-helix; the latter feature is typical of antimicrobial peptides. However, when the synthetic derivatives corresponding to the NH(2)-terminal (50 amino acids) and COOH-terminal (19 amino acids, corresponding to the putative alpha-helix) regions were compared, higher antibacterial activity was observed for the NH(2)-terminus-derived peptide, indicating that the holopeptide is necessary for full antibacterial activity. An artificial model of bacterial membranes confirmed these findings. The helical content of GCP-2/CXCL6 in the presence or absence of lipopolysaccharide or negatively charged membranes was studied by circular dichroism. As with many antibacterial peptides, membrane disruption by GCP-2/CXCL6 was dose-dependently reduced in the presence of NaCl, which, we here demonstrate, inhibited the binding of the peptide to the bacterial surface. Compared with CXC chemokines ENA-78/CXCL5 and NAP-2/CXCL7, GCP-2/CXCL6 showed a 90-fold-higher antibacterial activity. Taken together, GCP/CXCL6, in addition to its chemotactic and angiogenic properties, is likely to contribute to direct antibacterial activity during localized infection.

Details

Authors
Organisations
External organisations
  • Uppsala University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Infectious Medicine

Keywords

  • Amino Acid Sequence, Anti-Bacterial Agents, Antimicrobial Cationic Peptides, Blood Bactericidal Activity, Cell Membrane, Chemokine CXCL5, Chemokine CXCL6, Escherichia coli, Gram-Negative Bacteria, Gram-Positive Bacteria, Humans, In Vitro Techniques, Liposomes, Microbial Sensitivity Tests, Models, Molecular, Protein Structure, Secondary, Recombinant Proteins, Staphylococcus aureus, Streptococcus pyogenes, beta-Thromboglobulin, Journal Article, Research Support, Non-U.S. Gov't
Original languageEnglish
Pages (from-to)2599-2607
Number of pages9
JournalAntimicrobial Agents and Chemotherapy
Volume52
Issue number7
Publication statusPublished - 2008 Jul
Publication categoryResearch
Peer-reviewedYes