Peptide From Phage Library Enhances Endotoxin Neutralizing Activity Of PMB

OBJECTIVE: To select peptides that bind lipid A from a phage displayed library and verify the role of the peptides in neutralizing endotoxin.METHODS: Peptides were screened from a phage displayed peptide dodecamer library by using lipid A as a ligand. After three rounds of biopanning the eluted phages were characterized by phagemid ELISA and DNA sequencing. By model of LPS-induced TNF-¦Á secretion in human THP-1 cells, the affects of anti-endotoxin capability of the peptide, polymyxin B(PMB), and the peptide plus PMB were examined. RESULTS: 14 eluted clones were examined and bound lipid A specifically, and amino acid sequences of random peptide dodecamers of 4 positive clones were identical, named A1. Peptide A1 was solid-phase synthesized and purified on a C18 column. PMB, but not A1, suppressed LPS-induced TNF-¦Á secretion in human THP-1 cells. A1 enhanced the capability of PMB to suppress TNF-¦Á secretion, the endotoxin-neutralizing capability of 4 mg/L PMB plus 64 mg/L A1 was similar with 250 mg/L PMB. CONCLUSION: A peptide binding lipid A from phage displayed library has been selected. The peptide amplifies the endotoxin neutralizing activity of PMB.