Cathelicidin family of antibacterial peptides CAP18 and CAP11 inhibit the expression of TNF-alpha by blocking the binding of LPS to CD14(+) cells

• Published in: The Journal of immunology (1950) 2001-09, Vol.167 (6), p.3329-3338
• Main Authors: Nagaoka, I, Hirota, S, Niyonsaba, F, Hirata, M, Adachi, Y, Tamura, H, Heumann, D
• Format: Article
• Language: English
• Subjects: Acute-Phase Proteins; Amino Acid Sequence; Animals; Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - therapeutic use; Antimicrobial Cationic Peptides - pharmacology; Antimicrobial Cationic Peptides - therapeutic use; Carrier Proteins - metabolism; Cathelicidins; Cell Line; Depression, Chemical; Drug Evaluation, Preclinical; Gene Expression Regulation - drug effects; Guinea Pigs; Humans; Lipopolysaccharide Receptors - metabolism; Lipopolysaccharides - antagonists & inhibitors; Lipopolysaccharides - metabolism; Lipopolysaccharides - pharmacology; Macrophages - drug effects; Macrophages - metabolism; Macrophages, Peritoneal - drug effects; Macrophages, Peritoneal - metabolism; Male; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Prodrugs - pharmacology; Prodrugs - therapeutic use; Protein Binding - drug effects; RNA, Messenger - biosynthesis; Shock, Septic - prevention & control; Tumor Necrosis Factor-alpha - biosynthesis; Tumor Necrosis Factor-alpha - genetics
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.167.6.3329

Mammalian myeloid and epithelial cells express several kinds of antibacterial peptides (alpha-/beta-defensins and cathelicidins) that contribute to the innate host defense by killing invading micro-organisms. In this study we evaluated the LPS-neutralizing activities of cathelicidin peptides human CAP18 (cationic antibacterial proteins of 18 kDa) and guinea pig CAP11 using the CD14(+) murine macrophage cell line RAW264.7 and the murine endotoxin shock model. Flow cytometric analysis revealed that CAP18 and CAP11 inhibited the binding of FITC-conjugated LPS to RAW264.7 cells. Likewise, Northern and Western blot analyses indicated that CAP18 and CAP11 suppressed LPS-induced TNF-alpha mRNA and protein expression by RAW264.7 cells. Interestingly, CAP18 and CAP11 possessed LPS-binding activities, and they strongly suppressed the interaction of LPS with LPS binding protein that mediates the transport of LPS to CD14 to facilitate the activation of CD14(+) cells by LPS. Moreover, when CAP18 and CAP11 were preincubated with RAW264.7 cells, they bound to the cell surface CD14 and inhibited the binding of FITC-LPS to the cells. Furthermore, in the murine endotoxin shock model, CAP18 or CAP11 administration inhibited the binding of LPS to CD14(+) cells (peritoneal macrophages) and suppressed LPS-induced TNF-alpha expression by these cells. Together these observations indicate that cathelicidin peptides CAP18 and CAP11 probably exert protective actions against endotoxin shock by blocking the binding of LPS to CD14(+) cells, thereby suppressing the production of cytokines by these cells via their potent binding activities for LPS and CD14.