Effects Of Peroxisome Proliferator-activated Receptor A Ligand On Atherosclerosis And Thrombosis Mechanism

Aim: To investigate the effect of peroxisome proliferator-activated receptor (PPAR) a ligand on expression of TF (tissue factor) in monocyte and plasminogen activator inhibitor type-l(PAI-l) in endothelium , and to study the effect of PPARa ligand on cell adhesion and cell multiplication . Meanwhile, to study effect of ERK signaling pathway on PPARa ligand's influence on monocyte and endothelium . Accordingly to explain the mechanism of PPARa ligand influencing atherosclerosis and thrombosis in vitro . Methods: 1. Monocytic cells were divided into two groups (control group and treated group). PPARa ligand treated group were divided into two groups (fenofibrate and WY14643).The treated groups pretreated with PPARα ligand (fenofibrate and WY14643) respectively before stimulated by lipopolysaccharide (LPS). The mRNA expressions of tissue factor (TF) were detected by reverse transcriptase- polymerase chain reaction (RT-PCR). Protein level of TF were measured by westernblot. Immunocytochemistry SABC methods were used to identify the membrane protein expressions of TF in cells . 2. Endothelium were divided into groups as monocyte and incubated with PPARα ligands for 24h, RT-PCR were used to mesure the mRNA of tissue type plasminogen activator ( tPA) and plasminogen activator inhibior -1 (PAI-1), antigen presentation level of tPA and PAI-1 were identifid by enzyme linked immunosorbent assay (ELISA), protein expression of PAI-1 and ERK1/2 were detected by Westernblot. 3. Cell viability was measured by reduction of 3-[4,5-dimethylthia -2-yl]-2,5-diphenyl- tetrazolium bromide (MTT). 4. Mononuclear leukocytes were isolated by centrifugation. Following a period of incubation, the adherence of mononuclear cells to endothelial cells was determined. Results: 1. Abnormal elevation of TF level induced by LPS were markedly inhibited by two PPAR ligands in mononuclear cells. 2.WY14643 and fenofibrate markly inhibit the expression of PAI-1, however, did not change tPA level in endothelial cells. 3. PPARα ligands lessened proliferation of monocyte induced by LPS, and prevent the endothelium death caused by LPS in a dose-dependent manner. 4. PPARα ligands also reduced adherence rate between monocytic cells and endothelial cells. 5. fenofibrate and WY14643 havd confirmative effect on inhibiting phosphorylation ERK1/2 expression. Conclusions: 1. PPARα ligands can ameliorate atherosclerosis and thrombosis in many ways. 2. The effect of PPARα ligands is partly due to its functions as follow: repressing TF overexpression in monocyte induced by LPS; reducing PAI-1 creation in endothelial cells; inhibiting the proliferation of mononuclear cells and preventing endothelial cells from death induced by inflammative stimulation; attenuating adherence effect between monocytic cells and endothelial cells. 3.The ERK1/2 activation is at least partly involved in the process that PPARα ligands inhibit TF expression.