Interactions of a small linear cationic peptide with lipopolysaccharide and lipoteichoic acid

Cationic peptides are known to play critical roles in innate immunity. The peptides exert not only antimicrobial activity but also suppress the activity of lipopolysaccharide (LPS) and lipoteichoic acid (LTA) by binding to them. We have previously reported that L-peptide, a small linear cationic peptide derived from human granulysin displays broad-spectrum antimicrobial activity. In this study, the in vitro interactions of L-peptide with LPS and LTA were examined. LPS and LTA were found to inhibit the antimicrobial activity of the L-peptide in a dose-dependent manner, and they were shown to bind with the L-peptide. On the other hand, L-peptide failed to inhibit LPS- or LTA-induced cytokine production by macrophages or to block the binding of LPS to the cell surface. Thus, there seems to be a hierarchy that places LPS and LTA above L-peptide in the interactions of L-peptide with LPS and LTA.