Different contribution of interleukin-6 and cortisol activity to total plasma fibrin concentration and to acute mental stress-induced fibrin formation

Acute mental stress may contribute to atherosclerosis by affecting inflammation and coagulation; however, the crosstalk between inflammation and coagulation during stress has not been studied. In the present study, we investigated the association of plasma fibrinogen, plasma IL-6 (interleukin-6) and free salivary cortisol with the procoagulant marker D-dimer reflecting fibrin formation both over a 2-h period and in response to acute mental stress. Twenty-one male volunteers (mean age, 47 +/- 8 years) underwent the Trier Social Stress Test combining a 3-min preparation phase, a 5-min job interview and 5-min mental arithmetic test before an audience. IL-6, fibrinogen, D-dimer and cortisol were measured immediately before and after stress, and after 45 min and 105 min of recovery from stress. Two distinct areas under the curve were computed to obtain integrated measures of total protein activity over the entire 2-h period and of stress reactivity of proteins. IL-6 (P < 0.001), fibrinogen (P = 0.001), D-dimer (P = 0.021) and cortisol (P < 0.001) had all significantly changed across the four time points assessed, as determined by ANOVA. For the entire 2-h period, total fibrinogen activity (R-2 = 0.33, P = 0.007) and total cortisol activity (Delta R-2 = 0.17, P = 0.034) explained 50% of the variance in total D-dimer activity. Stress-induced changes in fibrinogen (R-2 = 0.47, P = 0.001) and IL-6 (Delta R-2 = 0.18, P = 0.008) together explained 65% of the variance in D-dimer reactivity to stress. Total fibrin formation was independently predicted by fibrinogen and hypothalamo-pituitary-adrenal activity. Pro-inflammatory and procoagulant changes with stress were associated. Aside from fibrinogen reactivity, IL-6 reactivity was an independent predictor of stress-induced fibrin formation.