Effect of lipid-bound apoA-I cysteine mutants on lipopolysaccharide-induced endotoxemia in mice

HDL has been shown to be able to neutralize the toxicity of lipopolysaccharide (LPS). Our previous study (J. Lipid Res. 2005. 46: 1303-1311) characterized the properties of secondary structure and in vitro functions of different cysteine mutants of apolipoprotein A-I. Here, we reconstituted recombinant HDLs (named rHDLwt, rHDL52, rHDL74, rHDL107, rHDL129, rHDL173, rHDL195, and rHDL228) by mixing wild type or those mutants with dipalmitoyl phosphatidylcholine and examined their in vivo effects on LPS-induced endotoxemia in mice. Our results showed that 24 h after injection, mice receiving rHDL74 or rHDL52 had a significant decrease of plasma tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta), compared with control mice receiving either saline or rHDLwt (P < 0.05). Administration of rHDL74 to mice injected with LPS also led to a decrease of plasma IL-6, protection of lung against acute injury, and attenuation of endotoxin-induced clinical symptoms in mice, compared with controls injected with LPS only. However, injection of rHDL228 significantly increased plasma concentration of TNF-alpha and exacerbated LPS-induced lung injury. In summary, compared with rHDLwt, rHDL74 and rHDL52 exhibit higher anti-inflammation capabilities, whereas rHDL228 shows hyper-proinflammation by exacerbating LPS-induced endotoxemia in mice.