Uremic medium causes expression, redistribution and shedding of adhesion molecules in cultured endothelial cells

Abstract

BACKGROUND AND OBJECTIVES: Patients with chronic renal failure show signs of accelerated atherosclerosis and high cardiovascular morbidity and mortality. Recent investigations indicate that uremia is associated with endothelial dysfunction and a microinflammatory state. We assessed changes in the expression of adhesion molecules [ELAM-1, VCAM-1 and ICAM-1], and proteins involved in hemostasis [von Willebrand factor (vWF) and thrombomodulin (TM)] in endothelial cells (ECs) and the corresponding extracellular matrices (ECM), respectively. DESIGN AND METHODS: Cultured human umbilical vein endothelial cells were incubated in the presence of a pool of normal or uremic sera. Immunocytochemical detection of related antigens was performed with specific antibodies coupled to colloidal gold. Concentrations of soluble adhesion molecules and TM in culture supernatants were evaluated by ELISA. Modifications in the transcription of the corresponding genes were also evaluated by Northern-blotting and reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Exposure of ECs to uremic media caused an increase in the presence [ELAM-1, VCAM-1] and accessibility [ICAM-1] of the adhesion receptors on EC monolayers, as well as a higher presence of their soluble molecules in culture supernatants. We found a significant increase in the presence of vWF on the extracellular matrix derived from ECs grown in the presence of a uremic medium. The presence of TM on ECs and in the ECM remained unmodified, although there was a significant increase in the presence of TM in supernatants from ECs grown in the presence of uremic sera. Northern-blot or RT-PCR studies showed increased expression of the mRNA for all the corresponding genes (ELAM-1, VCAM-1, ICAM-1, vWF and TM). INTERPRETATION AND CONCLUSIONS: Uremic medium causes inflammatory changes in ECs, which are characterized by enhanced expression, redistribution and shedding of adhesion molecules and TM, with an increased incorporation of vWF on the extracellular matrix generated.