| The mechanism of Multiple organ dysfunction syndrome(MODS) lesded by systemic inflammatory response syndrome(SIRS) is associated with uncontrolled host defense responses that lead to inflammation, endothelial damage, enhanced coagulation and diminished fibrinolysis. Vein endothelial cells (VEC) is the base of blood vessel endothelium, they always exposed in blood, and their various kinds of receptors on the surface were influenced by different factors, and lead VECs to produce and express various kinds of inflammation mediator which are associated with inflammation and coagulation.The C5a do its job both at SIRS and MODS,it not only can reglaution polymorphonuclear neutrophil (PMN) motion and activate inflammation cells to express promoptor factors to join systemic inflammatory response, but also can activate target cell, such as VECs and PMN, lead them to express lots of adhesion molecule, and then leads them activate,adhesion,traval to outside of blood vessel. At another side , C5a can activate VECs to express tissues factor and leads to coagulation in vessels. At partly of organ, C5a can regulate the expression of inflammation mediator, promopt PMN motion and assemble and injury VECs. All of this are pathological base of C5a works in MODS. C5a induce all of injury is based on combining with its receptor C5aR, blocking the combining with C5a and C5aR, perhaps, can restrain the pathological process which can be leaded by C5a.Thrombomodulin (TM,CD141) is a kind of glycoprotein producted by VECs on its surface, it is one of the receptors of thrombin, too.TM is a important role both at anti-coagulation and at anti- inflammation,and coagulation and inflammation are pathological base of MODS in SIRS. Another side, C5a is one of the reasons inducing SIRS. So by this study, we can know the regulation of VECs express TM by C5a and its mechanism,by this means, we can provide a new method for treat with SIRS.Objective:To investigate the effect of C5a on the express of thrombomodulin of Human umbilical vein endothelial cells (HUVECs).Methods: 1,HUVECs cultured in vitro were stimulated with C5a in 8,12,16,20 hours by concentration of 200 ng/ml, and by different concentrations of 100,200,300ng/ml in 12 hours respectively. 2,HUVECs cultured in vitro were stimulated by concentration of C5a with 200 ng/ml at 4h,8h,12h, and then interfered by antagonism polypeptide of C5a receptor(R4) with 2mg/L,at the end by 16h. 3,Use inhibitor of NF-κB (BAY 11-7082)by concentration of 2ug/ml culture HUVECs for 1h, and then stimulated by concentration of C5a with 200 ng/ml for 12h.TM expressions at mRNA levels and protein levels was detected by Real-time PCR and Western-blot respectively, and the dose and time depended effect of C5a on the expression of TM is evaluated.Results: 1,C5a down-regulates the TM expression at both protein and mRNA level. The down-regulation is time-dependence(1.1325±0.0397,0.8018±0.0256,0.7322±0.0436 at protein level and 4.0177±0.2046,0.3611±0.0351,0.1819±0.0146 (10-4)at mRNA level,both of them p<0.05) and dose-dependence : (0.9311±0.0157,0.7105±0.0339,0.6548±0.0429,0.6269±0.0403 at protein level and 3.0171±0.8040,0.3829±0.2024,0.0882±0.0027,0.0705±0.0080 (10-4) at mRNA level,both of them p<0.05).When concentration of C5a at 200 ng/ml is used to stimulate HUVECs for 12 hours, the underspeed of TM at mRNA level will slow down obviously;concentration of C5a at 300 ng/ml is used to stimulate HUVECs for 12 hours, the underspeed of TM at protein level will slow down obviously. 2,R4 can decrease the level of regulation of HUVEs express TM by C5a at protein and mRNA level, and the earlier interfered by R4 the decreasing of the down-regulation is more obviously. 3, NF-κB pathway is blocked, both at mRNA and protein level, the down-regulation of TM by C5a is decrease.Conclusions:1,C5a can depress the gene expression of TM, and then effect the protein's translation. By this means , C5a can lead to coagulation-accentuation and inflammation-injuries in sepsis.2, Block the combination between C5a and C5aR, the down-regulation of TM by C5a is decrease. This reveal that blocking the combining of C5a and C5aR can decrease the injury of coagulation-accentuation and inflammation-injuries in sepsis.3, Inhibit the of NF-κB can decrease the down-regulation of TM by C5a, This reveal that NF-κB pathway can regulate the express of TM.
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