Oxidized HDL induces cytotoxic effects: implications for atherogenic mechanism

Area of Science:

• Cardiovascular biology
• Immunology
• Lipid metabolism

Background:

• Atherosclerosis is an inflammatory disease driven by oxidized low-density lipoprotein (oxLDL).
• High-density lipoprotein (HDL) typically has antiatherogenic properties, but oxidative modification can impair its function.
• Understanding the proatherogenic role of oxidized HDL (oxHDL) is crucial.

Purpose of the Study:

• To investigate the proatherogenic effects of oxHDL in monocytes/macrophages.
• To compare the toxicity of oxHDL and oxLDL at similar malondialdehyde levels.
• To elucidate the molecular pathways involved in oxHDL-induced inflammation.

Main Methods:

• Comparative analysis of oxHDL and oxLDL toxicity on monocytes.
• Quantification of oxidative stress, inflammation, and cytotoxicity markers.
• Investigation of the NADPH oxidase/ROS-JNK/ERK pathway in oxHDL-induced MMP-9 formation.

Main Results:

• Both oxHDL and oxLDL induced oxidative stress, cytotoxicity, and release of TNF-alpha and MMP-9 in monocytes/macrophages.
• oxHDL demonstrated less potency than oxLDL in promoting these proatherogenic effects.
• oxHDL-induced MMP-9 formation was mediated by the NADPH oxidase/ROS-JNK/ERK pathway.

Conclusions:

• oxHDL exhibits proatherogenic properties, contributing to inflammation and cellular damage in monocytes.
• While less potent than oxLDL, oxHDL's effects on oxidative stress and inflammation are significant.
• The NADPH oxidase/ROS-JNK/ERK pathway is implicated in oxHDL-mediated MMP-9 production, highlighting a key mechanism in its atherogenic potential.