LACK OF PROTECTION AGAINST OXIDATIVE MODIFICATION OF LDL BY AVIAN HDL

Human and murine high density lipoprotein (HDL) has previously been sh own to decrease the accumulation of lipid peroxides on low density lip oprotein (LDL) under oxidising conditions. Several lines of evidence, including the ineffectiveness of HDL from paraoxonase knockout mice, s uggest that paraoxonase (PON1) located on HDL is responsible for its p rotective effect against lipid peroxidation. In this report we compare the effect of HDL from chicken, turkey and ostrich with human HDL on lipid peroxidation of LDL. Avian serum lacked PON1 activity and PON1 i mmunoactivity was also absent by ELISA and Western blotting whereas al l three techniques detected PON1 in a variety of non-avian species (co w, guinea-pig, rat, sheep, mouse, hamster, monkey and rabbit). Platele t activating factor acetyl hydrolase (PAFAH) activity was also absent from avian serum. Avian HDL isolated from plasma when incubated with h uman LDL was ineffective in preventing the Cu2+-induced accumulation o f lipid peroxides on this lipoprotein whereas human HDL under the same conditions was highly effective in this respect. Avian LDL was much m ore resistant to oxidation than human LDL, perhaps explaining the lack of HDL-PON1 and PAFAH, We conclude that these findings provide furthe r evidence than PON1 has an important role in the antiatherogenic/anti -inflammatory effects of HDL and that avian HDL can provide a valuable model which complements the use of HDL from paraoxonase knockout mice in the investigation of PON1 and PAFAH. (C) 1998 Academic Press.