Decreased Expression of Thrombomodulin in Endothelial Cells by Fibroblast Growth Factor-23/-Klotho

Chronic kidney disease (CKD) has been known to be a state of excessive fibroblast growth factor-23 (FGF23) and -Klotho deficiency. Patients undergoing hemodialysis have an increased mortality risk associated with cardiovascular disease and endothelial dysfunction. The mechanism responsible for the relationship of FGF23 to endothelial damage in these patients has been unclear. On the other hands, increasing evidences have demonstrated that thrombomodulin (TM) plays an important role in the endothelial barrier. Here, we report the suppression of membrane TM, in a dose-dependent manner, in human umbilical vein endothelial cells after FGF23 and FGF23/-Klotho stimulation. In addition, the levels of soluble TM, which reflect endothelial cell injury, were much higher in cell supernatants after FGF23 and FGF23/-Klotho stimulation than in the control supernatant. This study indicates a possible mechanism by which excessive levels of FGF23 are involved in endothelial TM disruption, which has been implicated as a potential cardiovascular risk factor in patients with CKD, especially in HD patients.