Cholesterol crystal-induced endothelial cell activation is complement-dependent and mediated by TNF

Area of Science:

• Cardiovascular Biology
• Immunology
• Cellular Biology

Background:

• Cholesterol crystals are key in atherosclerosis, contributing to plaque formation and rupture.
• Endothelial cell activation is crucial for recruiting inflammatory cells to atherosclerotic plaques.
• The precise mechanism by which cholesterol crystals induce endothelial activation and inflammation remains unclear.

Purpose of the Study:

• To investigate the role of cholesterol crystals in endothelial cell activation and inflammation.
• To elucidate the molecular pathways involved in cholesterol crystal-induced endothelial response.
• To explore the potential of targeting complement or TNF pathways for therapeutic intervention.

Main Methods:

• Developed a novel model using human umbilical vein endothelial cells and anticoagulated human whole blood.
• Assessed endothelial cell activation by measuring adhesion molecules (E-selectin, ICAM-1).
• Investigated the involvement of complement and TNF pathways using specific inhibitors and measured TNF release.

Main Results:

• Cholesterol crystals significantly increased endothelial E-selectin and ICAM-1 in a dose-dependent manner when incubated with whole blood.
• Endothelial activation was observed only in whole blood, not in medium alone or human serum, despite complement activation.
• Complement inhibitors (C3, C5) reduced endothelial activation by up to 89% and abolished TNF release.
• A TNF inhibitor (infliximab) reduced endothelial activation to baseline levels.

Conclusions:

• Endothelial activation by cholesterol crystals is primarily mediated by complement-dependent TNF release.
• These findings highlight a novel mechanism linking cholesterol crystals, complement, and TNF in atherogenesis.
• Targeting complement inhibition could be a potential therapeutic strategy to mitigate atherosclerosis-induced inflammation.