Cathelicidin family of antibacterial peptides CAP18 and CAP11 inhibit the expression of TNF-alpha by blocking the binding of LPS to CD14(+) cells.
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.
Nagaoka
I
I
Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan. nagaokai@med.juntendo.ac.jp
Hirota
S
S
Niyonsaba
F
F
Hirata
M
M
Adachi
Y
Y
Tamura
H
H
Heumann
D
D
D000209:Acute-Phase Proteins; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology* / Q000627:therapeutic use; D002352:Carrier Proteins / Q000378:metabolism; D054804:Cathelicidins; D002460:Cell Line; D003864:Depression, Chemical; D004353:Drug Evaluation, Preclinical; D005786:Gene Expression Regulation / Q000187:drug effects; D006168:Guinea Pigs; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D011355:Prodrugs / Q000494:pharmacology* / Q000627:therapeutic use; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis; D012772:Shock, Septic / Q000517:prevention & control*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000235:genetics; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D002352:Carrier Proteins; D054804:Cathelicidins; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011355:Prodrugs; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000099231:Lipopolysaccharide-Binding Protein; C440609:CAP11 protein, Cavia