Suppression of Inflammatory Cytokine Genes Expression in Vascular Endothelial Cells by Super-low Dose Lipopolysaccharide-activated Macrophages

Abstract

Background/Aim: Vascular endothelial cells play an important role in regulating immune responses and in keeping the balance between blood coagulation and fibrinolysis. Inflammatory cytokines produced by activated macrophages and vascular endothelial cells excessively activate vascular endothelial cells, leading to an imbalance in the expression of blood coagulation- and fibrinolysis-related factors. The dysfunction of vascular endothelial cells can lead to development of various diseases. In a previous study the increased expression of inflammatory cytokines in adipocytes was shown to be suppressed by the culture medium of macrophages activated by low-dose lipopolysaccharide (LPS). Suppressing inflammatory cytokine gene expression of low-dose LPS-activated macrophages may allow for the regulation of the dysfunction in vascular endothelial cells. Materials and Methods: Human monocytes THP-1 cells were differentiated into macrophages with phorbol 12-myristate 13-acetate (PMA) and were activated with LPS. The culture medium of the LPS-activated THP-1 was added to human aortic endothelial cells (HAoEC). After five days, the expression of inflammatory cytokine genes interleukin (IL)1B, IL6, IL8, and tumor necrosis factor (TNF)A, blood coagulation-related genes SERPINE1, tissue factor (TF), and thrombopoietin (TM), and fibrinolysis-related gene tissue-type plasminogen activator (t-PA) was analyzed using quantitative real-time PCR. Results: IL1B, IL8, SERPINE1, TF, and TM expression in HAoEC was significantly reduced in the culture medium of super-low dose (0.1 ng/ml) LPS-activated macrophages. Conclusion: Super-low dose LPS-activated macrophages can suppress vascular endothelial cell inflammation and may be useful in preventing various diseases caused by the dysfunction of activated vascular endothelial cells.