The effect of oxidized and unoxidized fibrinogen on apoptosis of endothelial cells

摘要

Oxidative stress plays an important role in cardiovascular diseases and atherosclerosis. Fibrinogen (FB), a central protein of the plasma coagulation cascade, is an independent risk factor of atherosclerosis. Importantly, it can be readily oxidized during oxidative stress and in various pathological conditions. Since endothelial dysfunction plays a key role in atherosclerosis it is interesting to investigate the effect of oxidized fibrinogen (ox-FB) on human umbilical vein endothelial cells (HEC). Here, we have investigated the effect of ox-FB on the development of programmed death of HEC incubated in vitro for 24 h under two different conditions: (1) at low serum level (0.1%) and in the absence of growth factors ("starvation"); (2) in full medium (5% human fetal serum) with growth factor supplement. Apoptosis was evaluated using analysis of nuclear morphology, phosphatidylserine externalization on the HEC surface and caspase-3 activation. Under starvation conditions characterized by significant cell death and activation of apoptosis addition of unoxidized FB significantly improved cell survival and prevented caspase-3/7 activation. In the presence of ox-FB caspase activity was 1.5 times higher than in the presence of FB, nevertheless, ox-FB demonstrated significant protection of HEC. Under optimal cultivation conditions FB caused a 3-fold decrease in the rate of apoptosis, while ox-FB improved cell survival but it was less active than FB. Thus, FB promoted HEC survival under stress conditions (in starvation), however, oxidative modification of this protein decreased its antiapoptotic activity.