Increased Wnt5a mRNA Expression in Advanced Atherosclerotic Lesions, and Oxidized LDL Treated Human Monocyte-Derived Macrophages

Objective: Wnt5a is a secreted glycoprotein highly present in atherosclerotic lesions. Uptake of oxidized-low density lipoprotein (ox-LDL) by monocytes/macrophages plays a critical role in atherosclerosis. The objective of this study was to determine if Wnt5a mRNA expression correlates with the severity of atherosclerotic lesions, and if, ox-LDL can induce Wnt5a mRNA in macrophages. Methods: Wnt5a mRNA in tissue sections from carotid arteries of patients undergoing endarterectomy was quantified via RT-PCR and correlated with plaque severity. Human monocyte-derived macrophages and differentiated THP-1 cells, a human monocytic cell line, were treated with ox-LDL or native-LDL. Subsequently, Wnt5a transcripts were quantified by RT-PCR. Results: Regions of the arteries with more severe plaques had detectable and significant levels of Wnt5a mRNA, while regions of the arteries containing less vulnerable plaques had low or non-detectable Wnt5a. Ox-LDL, but not native-LDL, induced Wnt5a mRNA in both human monocyte-derived macrophages and differentiated THP-1 cells. Conclusion: Our results demonstrate that the expression of Wnt5a correlates with the severity of atherosclerotic lesions, and that ox-LDL induces Wnt5a mRNA expression in human macrophages. These findings are consistent with the hypothesis that Wnt5a plays a critical role in atherosclerosis progression and that a source of Wnt5a is ox-LDL stimulated macrophages.