A NOVEL ENDOTOXIN ANTAGONIST ATTENUATES TUMOR-NECROSIS-FACTOR-ALPHA SECRETION

Twenty-seven amino acid peptides with sequences corresponding to a pro posed endotoxin binding region of bactericidal permeability increasing protein (BPI): 1) inhibit lipopolysaccharide induced macrophage tumor necrosis factor-alpha (TNF-alpha) secretion, 2) have bactericidal act ivity against gram-negative bacteria, and 3) protect mice from a letha l lipopolysaccharide (LPS) challenge. Unfortunately, peptides have a s hort half-life in vivo. Therefore, we have chemically conjugated the B PI based peptide, BG38, to a larger carrier protein, keyhole limpet he mocyanin (KLH), and characterized its ability: 1) to inhibit LPS induc ed macrophage TNF-alpha secretion and 2) to decrease plasma endotoxin and TNF-alpha levels following an i.v. injection of E. coli 0111:B4 LP S. BG38-KLH inhibited cultured macrophage TNF-alpha secretion in respo nse to LPS derived from four pathogenic strains of gram-negative bacte ria in a dose dependent manner (>90% inhibition at 50 mu g/ml, P < 0.0 5 Student's t test). BG38-KLH also decreased serum endotoxin (>90%, P < 0.05 Student's t test) and peak TNF-alpha levels (>30% inhibition, P < 0.05 Student's t test) following E. coli LPS challenge in a murine gram-negative bacterial sepsis model. Novel endotoxin antagonists base d upon a small domain of BPI represent promising reagents for the trea tment of serious gram-negative bacterial infections. (C) 1996 Academic Press, Inc.