Smoking is associated with altered endothelial-derived fibrinolytic and antithrombotic factors: An in vitro demonstration

Background - Data about the effects of smoking on thrombo-hemostatic factors (tissue factor [TF] and tissue factor pathway inhibitor [TFPI-1]) are limited and on fibrinolytic factors (tissue plasminogen activator [t-PA] and plasminogen activator inhibitor-1 [PAI-1]) are debatable. The present study investigated the smoking-related, endothelial cell (EC)-specific responses for these factors and their relation to nitric oxide (NO) production in vitro. Methods and Results - Serum from 8 nonsmokers and 15 smokers were incubated with confluent (≈85%) human umbilical vein endothelial cells (HUVECs) in 24-well tissue-culture plates for 12 hours. After the incubation, basal NO, t-PA, PAI-1, TF, TFPI-1 production, and substance P (SP)-stimulated NO, t-PA, and PAI-1 production were determined. HUVECs treated with smokers' serum showed lower basal (P<0.02) and SP-stimulated (P=0.059) t-PA production but similar basal and stimulated PAI-1 production (P=0.9 and P=0.6) compared with nonsmokers. Basal t-PA/PAI-1 molar ratio was significantly reduced in smokers (P<0.005). TFPI-1 level in the cell culture supernatant was also significantly lower in smokers compared with the nonsmoker group (P<0.05) with no difference in TF level between both groups (P=0.5). As previously reported, both basal (P<0.001) and SP-stimulated (P<0.05) NO production were significantly reduced in smokers. Basal TFPI-1 in culture correlated positively with basal NO production (r=0.42, P=0.04) and negatively with serum cotinine level (r=-0.6, P=0.01). Conclusions - These results indicate that cigarette smoking is associated with alterations in EC-derived fibrinolytic (t-PA) and antithrombotic (TFPI-1) factors. To our knowledge, this is the first demonstration that EC-derived TFPI is affected by smoking and endogenous NO or that the degree of smoke exposure may influence TFPI levels in an EC milieu.