Study On The Mechanism Of Endothelial Apoptosis Induced By Trans Fatty Acid

Trans fatty acids (TFA) is a common component of lipids and oil food. There are already a lot of report shows that TFA has a close relationship with the occurrence and development of heart cerebrovascular diseases, but the mechanism of TFA action on heart cerebrovascular diseases is still not clear. Endothelial cell dysfunction is the initial part of atherosclerosis (AS) and a lot of other heart cerebrovascular diseases, it plays an important role in the pathogenesis of AS. Endothelial cell cycle arrest and abnormal apoptosis of endothelial cells are important motivating factors which lead to endothelial cell dysfunction, they play an important role in the development of AS procession.The research about TFA effecting on AS and other heart cerebrovascular diseases, mainly focus on two aspects:endothelial cell dysfunction and endothelial cell apoptosis, and the object of study mostly is a mixture of trans fatty acids, there is little research for a single species trans fatty acids action with AS and other heart cerebrovascular diseases. In view of the growing intake of TFA in Chinese residents and our current situation with little research about TFA and human health, the study about the action of TFA and its effecting mechanism on AS has obvious theoretical value and social significance. The topics studied for elaidic acid with AS and other heart cerebrovascular diseases, mainly through elaidic acid effect on umbilical vein endothelial cells (HUVEC) for dysfunction and endothelial cell cycle and apoptosis, to discuss elaidic acid induced atherosclerosis mechanism through the p53mediated apoptosis and supplement downstream mechanism of apoptosis induced by caspase cascade and provide important theoretical basis and scientific data for the relationship of trans fatty acids and cardiovascular disease and the prevention and treatment of cardiovascular disease.Endothelial cell dysfunction indicators are detected by ELISA, such as the change of P-selectin, sICAM-1, TNF-a, ET-1, TXA-2and PGI2in cell culture medium before and after elaidic acid action, to determine the effect for different concentration of TFA on endothelial cell dysfunction; Endothelial cell apoptosis rate is detected by flow cytometry; The changes of CDK4and PA28γ which is related to the cell cycle and apoptosis in endothelial cells are detected by Western-blot before and after elaidic acid action; The changes of mRNA expression related protein with cell apoptosis, such as p21, p53, Bcl-2, CDK4, Cyclin D1, PA28y are detected by RT-PCR, which can detect TFA action on endothelial cell dysfunction and cell cycle and apoptosis quantitatively and explore the mechanism of elaidic acid induced atherosclerosis trough p53-mediated apoptosis. The obtained results are as follows:1.TFA increased the secretion of cell dysfunction biological markers such as P-selectin, sICAM-1, ET-1, TXA-2and TNF-a, decreased the secretion of PGI2. A large number of P-selectin and sICAM-1can cause the adhesion between microvascular endothelial cells and neutrophil cells, resulting in the piercing from leukocyte to capillary wall, causing the inflammatory response of local tissue, leading the dysfunction of endothelial cell. The increased of TNF-a secretion, will easy to exacerbate the inflammatory response and the imbalance of regulation between anti-inflammatory cytokines and pro-inflammatory cytokines, result in systemic inflammatory response syndrome, which causes multiple organ dysfunction. The rise of ET-1may cause local microcirculation, promote thrombosis and accelerate the process of inflammation and AS. At the same time, the elevated ET-1can inhibit the synthesis and release of PGI2, while promoting the secretion of TXA-2, which lead to the imbalance of PGI2/TXA-2regulation, increased vascular tone, cause the blood in hypercoagulable state, and increase the concurrent incidence of cardiovascular and cerebrovascular. Various indicators show that TFA can cause endothelial cell dysfunction.2.Cell apoptosis rate was increased after TFA action on HUVEC, and the influence of high concentrations of elaidic acid has greatly improved for early apoptosis rate and late apoptosis rate and after the effect of low concentrations of elaidic acid, the apoptosis rate was creased, but little impact.3.Western-blot test results showed that after TFA role in endothelial cells,the expression of CDK4was decreased significantly and dose-dependent manner,the decrease of CDK4cause the cells remaining in GO/G1phase, reducing the cell ratio of S and G2/M, blocking the cell cycle progression, leading the cell cycle arrest and accelerating cell apoptosis. The expression of PA28y was decreased, which can weaken the negative feedback effect of Mdm2to p53, prevent the degradation of p53, the cells stagnant in the G1, and the DNA damage can not be repaired, resulting in apoptosis. The results showed that the TFA can lead to cell cycle arrest and accelerated cell apoptosis.4.Detected by RT-PCR, the mRNA expressions of p21and p53in cells after elaidic acid effect were increased, and the mRNA expression of Bcl-2, CDK4, Cyclin D1and PA28y were reduced with the change of elaidic acid concentration. The decreased PA28y can result in increasing the expression of p53, enhance the inhibition of Bcl-2, reduce the apoptosis inhibition action of Bcl-2, activate the Caspase9, and then activate the Caspase3and appear apoptosis. Elevated expression of p53can increase the expression of transcripts p21, which will decline CDK4, CyclinDl, and weaken the transition regulation of CDK4/CyclinD1from G1to S phase, resulting in G1arrest, the cells are unable to complete normal mitosis, which can lead to cell apoptosis. The results showed that elaidic acid can induce cell cycle arrest leading to cell death trough activate p53and then activate the p21, in the other way, it can activate the p53, and then activate the Bcl-2mitochondrial protein activation pathway, lead to apoptosis, ultimately.In summary, TFA can cause endothelial cell injury trough up regulating various types of inflammation and cytokines in the endothelial cells and lead to endothelial cell dysfunction, promote the process of inflammation. In addition, TFA can induced endothelial cell apoptosis and increase the mRNA expression of endothelial cell cycle and apoptosis-related protein trough p53-mediated endothelial cell apoptosis and cell block.