The effect of homocysteine on fibrinolytic system in human umbilical vein endothelial cells / 中华心血管病杂志

ABSTRACT

<p><b>OBJECTIVES</b>To investigate the relationship between homocysteine (Hcy) and the fibrinolytic system in acute myocardial infarction (AMI) and human umbilical vein endothelial cells (HUVEC).</p><p><b>METHODS</b>Cultured HUVEC was divided into 10 groups (0, 10, 50, 200, 500 micromol/L Hcy with or without 15 micromol/L of folic acid). There were 53 patients of acute myocardial infarction (AMI) and 48 healthy controls. The plasminogen activator inhibitor-1 (PAI-1) and activator of plasminogen (tPA) antigen levels in HUVEC's supernatant and plasma were measured with Elisa kit. Concentration of plasma Hcy was measured by reverse-phase high-performance liquid chromatography with precolumn derivatization and fluorometric detection in the patients and healthy controls. Total RNA was extracted using the guanidinium isothiocyanate method. The semi-quantification of PAI-1 and tPA mRNA in HUVEC was carried out by reverse transcriptase-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>(1) PAI-1 mRNA and secreted protein levels were both significantly enhanced by Hcy at the concentration of 500 micromol/L, compared with the control group (P < 0.05). (2) The tPA mRNA and antigen levels were decreased significantly at concentration of 500 micromol/L of Hcy, compared with that of 10 micromol/L Hcy (P < 0.05), but compared with the control group (0 micromol/L), the tPA mRNA and antigen levels of 10 micromol/L of Hcy were much higher (P < 0.05). (3) The addition of folic acid reduced PAI-1 but increased tPA at both mRNA and protein levels, which were both obvious at concentrations of 500 micromol/L Hcy, compared with only Hcy group (P < 0.05). (4) Hcy, tPA, and PAI-1 antigen levels were increased in AMI group. Hcy is a independent risk factor of AMI (P < 0.05). There weren't significant correlation between Hcy and tPA or Hcy and PAI-1 in both groups (P > 0.05), although the coefficient correlation was higher in patients than in controls.</p><p><b>CONCLUSIONS</b>These results suggested that hyperhomo-cysteinemia increased the incidence of thrombotic disease, which may be caused by decreasing the activity of fibrinolytic system, whereas, folic acid may be protective against the toxic action of Hcy.</p>