(129i) Interfacial Properties Influencing Lipopolysaccharide Uptake By Lipid Droplets

Lipoproteins play a key role in clearing lipopolysaccharide (LPS) released by bacteria from the bloodstream during infections by binding and removing it. The efficiency of this process depends on the physicochemical properties of lipoproteins and environmental factors. In our study, we used synthetic lipid droplets as lipoprotein mimics to identify critical factors influencing LPS uptake. We varied the charge, size, and lipid composition of the droplets and examined the roles of LPS-binding protein (LBP) and Ca²⁺ and Mg²⁺ ions in LPS adsorption. Our results showed that amphiphilic LPS spontaneously binds to the lipid droplet surface, even without LBP, though LBP significantly enhances uptake. Positively charged lipid droplets proved more effective at capturing negatively charged LPS. Notably, adding Ca²⁺ ions at near-physiological concentrations significantly increased LPS uptake, underscoring Ca²⁺’s critical role in LPS clearance. Given that sepsis patients often exhibit hypocalcemia and reduced lipoprotein levels, supplementing Ca²⁺ alongside synthetic lipoproteins could offer a promising therapeutic approach for severe sepsis.