[Soluble thrombomodulin: a specific parameter of endothelial injury]

Thrombomodulin (TM) is a constituent glycoprotein of endothelial cell membrane, and soluble TM is present also in plasma and urine. It was revealed by experiments using cultured HUVEC in vitro that TM is released from endothelial cell membrane not with monensin, thrombin, fibroblast growth factor, interleukin-1 or endotoxin, but with H2O2 or endotoxin-treated granulocytes. And the release was suppressed by the coexistence of gabexate mesilate or superoxide dismutase. It was suggested that soluble TM was released from endothelial cell membrane by its injury and digested to multiple molecular forms by endogenous and granulocytic protease(s). TM level in circulation is increased in cases of SLE, MCLS, diabetic angiopathy. It was increased in cases of overt DIC and decreased to the normal level when the patient was recovered from DIC. TM level in circulation was also increased in cases of decompensated liver cirrhosis and markedly in cases of renal insufficiency. It was concluded that plasma TM is a parameter reflecting endothelial injury due to inflammation or metabolic disorders of vascular system. But the interpretation of increased plasma TM was difficult when renal insufficiency was complicated.