The impact of anti-endothelial cell antibodies (AECAs) on the development of blood vessel damage in patients with systemic lupus erythematosus: the preliminary study.

Vascular injury represents one of the most frequent lesions in systemic lupus erythematosus (SLE). The aim of the study was to assess the influence of anti-endothelial cell antibodies (AECAs) on the development of endothelial cell (EC) activation, dysfunction and subsequent vasculitis in women with SLE. Fifty six women with SLE were divided into 2 subgroups, i.e. subjects with positive AECAs (+) and those with negative AECAs (-). The control group consisted of 25 healthy women. Clinical characteristics, routine laboratory tests and circulating markers of EC activation/dysfunction, i.e. monocyte-chemotactic protein-1 (MCP-1), soluble E- and P-selectin, vascular and intercellular adhesion molecule-1 (sVCAM-1, sICAM-1), von Willebrand factor (vWF), pentraxin 3 (the marker of vasculitis) the indicator of procoagulant activity i.e. prothrombin fragment 1 + 2 (F1 + 2) were detected using ELISA and compared between patients with AECA (+), AECA (-) and control subgroups. Serum concentrations of AECAs in AECA(+), AECA(-) and control groups were 4.58 ± 2.97, 0.92 ± 0.50 and 0.72 ± 0.28 AU/ml, respectively (p < 0.001). The study showed significant increases in EC activation markers, i.e. MCP-1, sE-selectin, sVCAM-1 and F1 + 2 in SLE AECA(+) compared to SLE AECA(-) and control groups. However, the indicator of vasculitis (PTX3) was significantly lower in SLE AECA(+). Moreover, multivariate analysis of variance showed a positive correlation between AECAs and sE-selectin and sVCAM-1 levels, but not with PTX3. AECAs were involved in the initial stages of vascular damage in SLE, i.e. in EC activation and dysfunction. However, they did not play a role in the development of vasculitis.

The Effect of Platelet-Rich Plasma on Endothelial Progenitor Cell Functionality.

Platelets mediate circulating endothelial progenitor cell (EPC) recruitment and maturation, participating in vascular repair, however the underlying mechanism(s) remain unclear. We investigated the effect of platelet-rich plasma (PRP) on the functionality of CD34+-derived late-outgrowth endothelial cells (OECs) in culture. Confluent OECs were coincubated with PRP under platelet aggregation (with adenosine diphosphate; ADP) and nonaggregation conditions, in the presence/absence of the reversible P2Y12 platelet receptor antagonist ticagrelor. Outgrowth endothelial cell activation was evaluated by determining prostacyclin (PGI2) and monocyte chemoattractant protein-1 (MCP-1) release and intercellular adhesion molecule-1 (ICAM-1) membrane expression. Similar experiments were performed using human umbilical vein endothelial cells (HUVECs). Platelet-rich plasma increased ICAM-1 expression and PGI2 and MCP-1 secretion compared with autologous platelet-poor plasma, whereas ADP-aggregated platelets in PRP did not exhibit any effect. Platelet-rich plasma pretreated with ticagrelor prior to activation with ADP increased all markers to a similar extent as PRP. Similar results were obtained using HUVECs. In conclusion, PRP induces OEC activation, a phenomenon not observed when platelets are aggregated with ADP. Platelet inhibition with ticagrelor restores the PRP capability to activate OECs. Since EPC activation is important for endothelial regeneration and angiogenesis, we suggest that agents inhibiting platelet aggregation, such as ticagrelor, may promote platelet-EPC interaction and EPC function.