Dietary lipid lowering reduces tissue factor expression in rabbit atheroma

Area of Science:

• Cardiovascular Research
• Atherosclerosis Pathophysiology
• Thrombosis Mechanisms

Background:

• The precise mechanisms by which lipid-lowering therapies reduce thrombotic complications in coronary atherosclerosis are not fully understood.
• Tissue factor (TF) overexpression in atheroma may promote thrombus formation following plaque disruption.
• CD40 ligand (CD40L) is known to enhance TF expression in vitro.

Purpose of the Study:

• To investigate whether lipid lowering decreases TF expression and activity in an experimental model of atherosclerosis.
• To explore the relationship between lipid lowering, TF, CD40L, and CD40 in atheroma.

Main Methods:

• Atheroma was induced in rabbit aortas via balloon injury and cholesterol feeding.
• Lipid lowering was achieved by switching to a chow diet.
• Expression and localization of TF, CD40L, and CD40 were quantified using immunolocalization and image analysis.
• TF activity and mRNA levels were assessed using chromogenic assays and RT-PCR.

Main Results:

• TF was highly expressed in atheroma macrophages, smooth muscle cells, and endothelial cells, colocalizing with CD40L and CD40.
• Lipid lowering significantly reduced TF protein and mRNA expression, along with CD40L and CD40.
• In situ binding of TF to factors VIIa and X decreased after lipid lowering, indicating reduced TF activity.

Conclusions:

• These findings suggest that reduced expression and activity of tissue factor (TF) represent a novel mechanism through which lipid lowering mitigates thrombotic complications in atherosclerosis.
• Targeting TF may offer a therapeutic strategy to prevent atherothrombotic events.