Objective Our previous study has shown that resistin, one of the adipokines elevated in metabolic syndrome, is strongly associated with thrombotic complications in patients with metabolic syndrome. The mechanism, however, is far from elucidated. The present study was designed to observe the effect of resistin on the expressions of fibrinolytic factors, including tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) in human vascular endothelial cells, and to investigate the cellular mechanisms.
Methods Human umbilical vein endothelial cells (HUVEC) within 3–5 passages were incubated with different concentrations of resistin (25, 50, 100 ng/ml) for various times (durations) (6, 24, 48 h), respectively. Then, HUVEC were preincubated with MAPK pathway (ERK, p38 MAPK and JNK) inhibitors before resistin treatment. The supernatant protein levels of tPA and PAI-1 were measured by ELISA; (following which the) mRNA levels of tPA and PAI-1 were assayed by real time RT-PCR; The activation of MAPK was (then) characterised by western blot analysis.
Results (1) Resistin decreased tPA antigen level and increased PAI-1 antigen level in HUVEC both in time-and concentration-dependent manners (p<0.05), with the maximum effect of 50 ng/ml resistin treatment for 48 h (p<0.01). Resistin also significantly reduced tPA mRNA level and upregulated PAI-1 mRNA level in HUVEC. (2) Neither PD98059 (ERK1/2 inhibitor) nor SP600125 (JNK inhibitor), but only SB203580 (p38 MAPK inhibitor) blocked the regulation of resistin on t-PA and PAI-1 significantly. (3) Resistin activated the phosphorylation of p38 MAPK in HUVEC.
Conclusions Resistin may accelerate thrombosis development by impairing fibrinolytic activity in vascular via p38 MAPK dependent pathway in metabolic syndrome. Abbreviations: mitogen-activated protein kinase (MAPK), plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), Human umbilical vein endothelial cells (HUVEC), enzyme-linked immunosorbent assay (ELISA), reverse transcription PCR.
- tissue plasminogen activator (t-PA)
- plasminogen activator inhibitor-1 (PAI-1)
- mitogen activated protein kinase (MAPK)