Physicochemical properties of bacterial pro-inflammatory lipids influence their interaction with apolipoprotein-derived peptides

Apolipoprotein-derived peptides have emerged as a promising candidate for the treatment of various inflammatory disease conditions. Multiple mechanisms have been proposed to explain the beneficiary effects of these peptides and prominent among them being high-affinity binding of peptides to pro-inflammatory lipids and facilitating their sequestration/metabolism/clearance in the body. Pro-inflammatory lipids differ considerably in their molecular structures, chemical compositions and physicochemical properties. Importance of the properties of the pro-inflammatory lipids in their ability to bind to apolipoprotein-derived peptides is not studied in details. In this study, we have characterized the interaction of synthetic peptides derived from human apolipoprotein E with lipopolysaccharide (LPS) and lipoteichoic acid (LTA), two potent bacterial pro-inflammatory lipids that differ considerably in their molecular structures and chemical compositions. Binding of the peptides to LPS and LTA was monitored by CD spectroscopy. Effect of the peptides on the biological activity of lipids was studied by monitoring the inhibition of LPS- or LTA-induced up-regulation of the inflammatory markers in the human blood cells. Physicochemical properties of lipid aggregates were determined by fluorescence spectroscopy and native PAGE. Our results show that physicochemical properties of LPS and LTA differ considerably and influence their interaction with apolipoprotein-derived peptides.