| Summary: | 碩士 === 國立成功大學 === 醫學檢驗生物技術學系碩博士班 === 96 === Thrombomodulin (TM) is a glycoprotein which is first identified on the surface of vascular endothelial cells (ECs). TM activates anticoagulation through thrombin-mediated formation of activated protein C. It has recently been reported that the extracellular N-terminal lectin-like domain (D1) of TM possesses anti-inflammatory properties. Our previous results show that TMD1 could suppress lipopolysaccaride-induced acute inflammatory responses. However, the detailed mechanisms of TMD1 in chronic inflammation, such as atherosclerosis, are still unknown. To further investigate the role of TMD1 in atherosclerosis, we prepared and purified recombinant TMD1 wild-type protein and its mutants, TMD1 Ala25Thr and Gly61Ala, using Pichia pastoris expression system. These two mutants are naturally occurring polymorphisms in TMD1 and significantly correlated with thromboembolic diseases, such as sagittal sinus thrombosis or myocardial infarction. In vitro study showed that TMD1 had no significant effect on the expression of cell adhesion molecules on tumor necrosis factor-α-stimulated human umbilical vein endothelial cells. However, TMD1 blocked the adhesion and the transendothelial migration of monocytes by binding to Lewisy which decorates adhesion molecules on ECs. Besides, the inhibitory effects of TMD1 mutants on adhesion and migration of monocytes were reduced. In vivo, the apolipoprotein E knockout mice were injected intraperitoneally with different doses of recombinant TMD1 protein. The data showed that the area of atherosclerotic plaque in mice aortas were reduced in the TMD1-treated groups in a dose-dependent manner. We also found that the effects of TMD1 mutants on atherosclerotic plaque formation were partially reduced compared with wild-type. In conclusion, TMD1 may suppress atherosclerosis by inhibiting the interaction between monocytes and ECs through binding to Lewisy.
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