Activation of platelets and cellular coagulation in cerebral small-vessel disease.

Platelets and monocytes play a pivotal role in the initiation and progression of large-vessel atherosclerosis. An up-regulation of various platelet and coagulation activation markers has been described in cardiovascular diseases and in patients with acute cerebral ischemia. In the present study the role of platelets and cellular coagulation activation in cerebral small-vessel disease (cSVD) was assessed. In 24 patients with cSVD but without established large-vessel disease, whole blood samples were obtained. Patients were divided into three subgroups (Fazekas 1, 2 and 3) according to extent of cSVD based on morphological magnetic resonance imaging criteria. Surface expression of CD40L and CD62P on platelets, tissue-factor exposition on monocytes and platelet-monocyte aggregates were measured with flow cytometry. Plasma levels of soluble CD40L, interleukin (IL)-6 and IL-7 were assessed by ELISA. Patients with cSVD show a significantly elevated expression of platelet CD40L (P < 0.001) and CD62P (P < 0.023), significantly elevated amounts of platelet-monocyte aggregates (P < 0.004), a significantly enhanced tissue-factor exposition on monocytes (P < 0.019) and significantly lower plasma levels of IL-7 compared to 10 healthy controls. However, this platelet and monocyte activation did not correlate with the severity of cSVD. Patients with cSVD show an up-regulation of the platelet CD40L and CD62P system and an activation of cellular coagulation which might contribute to the initiation and progression of cSVD.