Background.

Upon exposure to cytokines, endothelial cells may undergo profound alterations of vasomotor function. In this study, we characterized the relation-ship between coronary epicardial and microvascular vasomotor function and expression of specific cytokine patterns in human heart transplant recipients.

Methods.

We studied 49 cardiac transplant recipients, without acute rejection or infection at an average of 6±3 months after transplantation. Coronary resistance vessel function was measured in an endothelium-dependent manner with acetylcholine (5 and 150 μg/5 min; intracoronary injection) and in an endothelium-independent manner with adenosine (400 and 800 μg/5 min; intracoronary injection) using an intracoronary Doppler flow wire. Simultaneous epicardial diameter changes were measured using quantitative coronary angiography. Coronary sinus and aortic serum levels of soluble interleukin (IL)-2 receptor and soluble tumor necrosis factor-α receptors (sTNF-R1 and sTNF-R2), TNF-α, and IL-6 were determined. Transcardiac cytokine release (coronary sinus minus aortic levels) was correlated with coronary vasomotor function.

Results.

The highest amounts of cardiac cytokine release were observed for IL-6 (32±14% increase) and sTNF-R1 (26±13% increase). A significant inverse correlation between microvascular endothelial function and cardiac release of soluble IL-2 receptor (P= 0.04) and IL-6 (P= 0.03) was detected, whereas a positive correlation was observed to sTNF-R1 (P= 0.004). Distal epicardial endothelial vasomotion was inversely correlated to transcardiac sTNF-R2 release (P= 0.03).

Conclusions.

Cytokine production and activation, a common phenomenon early after heart transplantation, is related at least in part to endothelial vasomotor dysfunction of the epicardial and microvascular compartment. These results support the hypothesis that coronary endothelial dysfunction after cardiac transplantation is an immunologic phenomenon. Since endothelial dysfunction seems to be a crucial step in the pathogenesis of cardiac allograft vasculopathy, coronary cytokine suppression should be a therapeutic target of improved future immunosuppressive regimens.