Desialylated endothelial cells membrane enhance its fibrinolytic potential

Background

Endothelial cell dysfunction may be implicated in the development of multiple organ failure (MOF) by a number of mechanisms. Among these, altered plasma fibrinolysis promotes fibrin deposition, which may create microvascular alterations. Previously, we observed that critically ill patients were characterized by a more marked red blood cell membrane and transferrin desialylation (sialic acid removed) [1, 2] in septic patients. Sialic acid (SA), due to its negative charge, is involved in diverse cell–cell, cell–molecule and molecule–molecule interactions. We aimed to test the effect of endothelial cell membrane desialylation on the complete fibrinolysis process (coagulation and fibrinolysis) at the surface of endothelial cells in vitro.

Methods

The endothelial cell line Ea.hy926 was used. The cells were inoculated on polyethylene terephtalate (PET) microporous membrane, in glass circular microcuvettes (51 mm²) and grown for 6 days until confluence in DMEM with 10% FBS. The cell were incubated for 20 min in medium containing 0.5 U, 1 U and 2 U neuraminidase. To study the fibrinolysis process, a euglobulin fraction (a plasma fraction) was placed on the cell surface, and the clotting was induced by thrombin addition. The lysis time was measured in a newly designed apparatus and expressed in minutes [3].

Results

The results are expressed as the ratio of the lysis time of treated cells to control cells. Neuraminidase treatment (1 U and 2 U) induced a 0.79-fold and 0.83-fold decrease in lysis time (ANOVA; n = 6: P < 0.001). This indicates an increase of fibrino-lytic activity.

Conclusion

In this work, we show the importance of SA in fibrinolytic activity of endothelial cell membranes. This mechanism could protect the endothelium from the fibrin deposition. The fact that desialylation occurs in the bloodstream from septic patients could also impair the endothelium function. Studies are needed to determine the possible desialylation of endothelial cells in sepsis and the implications of this mechanism in the physiopathology of sepsis.