Oxidized LDL-mediated upregulation of ADAMTS-4 in monocytes/macrophages involves ROS-NF-κB-SIRT-1 pathway.

Background and aims: ADAMTS-4 is a protease enzyme involved in vascular remodeling and atherosclerosis. It was found to be upregulated in macrophages seen in atherosclerotic lesions. This study aimed to investigate the expression and regulation of ADAMTS-4 in oxidized LDL-induced human monocytes/macrophages system.

Methods: Peripheral blood mononuclear cells (PBMCs) isolated from human blood, and treated with oxidized LDL (50 μg mL-1) were used as the model system for the study. mRNA and protein expressions were studied by PCR, ELISA, and western blot analysis. ROS production and cell viability were determined by DCFDA staining and MTT assay, respectively.

Results: In the presence of oxidized LDL, monocytes get differentiated into macrophages, which were confirmed by the increased expression of macrophage differentiation markers and pro-inflammatory cytokine TNF-α. Oxidized LDL increased the mRNA and protein expression of ADAMTS-4 in monocytes/macrophages. N- Acetyl cysteine, ROS scavenger, downregulate the protein expression of ADAMTS-4. The expression of ADAMTS-4 was decreased significantly in the presence of NF-κB inhibitors. SIRT-1 activity was significantly downregulated in the macrophages and was reversed in the presence of the SIRT-1 agonist, resveratrol. Acetylation of NF-κB and hence the expression of ADAMTS-4 were significantly downregulated in the presence of SIRT-1 activator, resveratrol.

Conclusions: Our study suggests that oxidized LDL significantly upregulated the expression of ADAMTS-4 in the monocytes/macrophages through ROS- NF-κB- SIRT-1 pathway.