The in vitro effect of oxidized LDL and PHA on proliferation and gene expression of regulatory T cells in patients with atherosclerosis.

Atherosclerosis is a chronic inflammatory condition that affects the arterial wall. Oxidized low- density lipoprotein (ox-LDL) seems to have an important role in atherosclerotic plaque formation. This study was performed to investigate the effects of ox-LDL as well as PHA on proliferation and gene expression of  peripheral blood  mononuclear  cells (PBMCs) in patients with atherosclerosis compared  to  healthy controls. Proliferation of  PBMCs was assessed by BrdU assay, while gene expression was assessed by real-time PCR. Both PHA and ox-LDL significantly induced proliferation of PBMCs of patients and controls. PBMCs  from  controls  showed  significantly higher  proliferation  when  stimulated  with  ox-LDL compared to patients. Expression of TGF-β was significantly lower in PBMCs from patients compared to healthy controls (p<0.001). Following simulation with PHA, TGF-β and Foxp3 gene expression levels in patients and controls were significantly decreased (p<0.001). Expression of Foxp3 in PBMCs treated with ox-LDL was significantly decreased in patients and controls. Decreased expression of TGF-β and Foxp3 genes after ox-LDL stimulation may be due to more sensitivity of Treg cells than effector T cells to ox-LDL. Presence of ox-LDL within atheroma could be associated with the diminished population of Treg cells in the atherosclerotic patients.