Aggregated low density lipoproteins decrease metalloproteinase-9 expression and activity in human coronary smooth...

Area of Science:

• Cardiovascular Biology
• Atherosclerosis Research
• Cellular and Molecular Medicine

Background:

• Vascular smooth muscle cell (VSMC) function is crucial for plaque stability.
• Metalloproteinases (MMPs), particularly MMP-9, play a role in regulating VSMC migration and plaque phenotype.
• The effect of aggregated LDL (agLDL) on MMP-9 production in VSMCs is not well understood.

Purpose of the Study:

• To investigate the impact of lipid loading via agLDL internalization on MMP-9 and MMP-2 expression and activity in human VSMCs.
• To assess the consequences of agLDL exposure on VSMC migration.

Main Methods:

• Human VSMCs were exposed to aggregated LDL (agLDL) and native LDL (nLDL).
• MMP-9, MMP-2, and TIMP-1 expression and activity were analyzed.
• VSMC migration was assessed using a scratch-wound healing assay.

Main Results:

• agLDL internalization significantly down-regulated MMP-9 activity in a time- and dose-dependent manner.
• nLDL showed a similar but less sustained decrease in MMP-9 activity.
• Neither agLDL nor nLDL affected MMP-2 or TIMP-1 levels.
• agLDL exposure markedly reduced VSMC regrowth after injury, indicating inhibited migration.

Conclusions:

• Lipid loading by agLDL internalization reduces MMP-9 activity in VSMCs.
• This reduction in MMP-9 activity is associated with inhibited VSMC migration.
• agLDL-induced changes in MMP-9 may influence vascular remodeling and atherosclerotic plaque stability.