Microparticles from Patients with Multiple Organ Dysfunction Syndrome and Sepsis Support Coagulation through Multiple Mechanisms

Abstract

Summary Aim. We investigated the occurrence and thrombin generating mechanisms of circulating microparticles (MP) in patients with multiple organ dysfunction syndrome (MODS) and sepsis. Methods. MP, isolated from blood of patients (n = 9) and healthy controls (n = 14), were stained with cell-specific monoclonal antibodies (MoAbs) or anti-tissue factor (anti-TF) MoAb and annexin V, and analyzed by flow cytometry. To assess their thrombin-generating capacity, MP were reconstituted in normal plasma. The coagulation activation status in vivo was quantified by plasma prothrombin fragment F1+2- and thrombin-antithrombin (TAT) measurements. Results. Annexin V-positive MP in the patients originated predominantly from platelets (PMP), and to a lesser extent from erythrocytes, endothelial cells (EMP) and granulocytes (GMP). Compared to healthy controls, the numbers of annexin V-positive PMP and TF-exposing MP were decreased (p = <0.001 for both), EMP were decreased (E-selectin, p = 0.003) or found equal (CD144, p = 0.063), erythrocyte-derived MP were equal (p = 0.726), and GMP were increased (p = 0.008). GMP numbers correlated with plasma concentrations of elastase (r = 0.70, p = 0.036), but not with C-reactive-protein or interleukin-6 concentrations. Patient samples also contained reduced numbers of annexin V-negative PMP, and increased numbers of erythrocyte-derived MP and GMP (p = 0.005, p = 0.021 and p <0.001, respectively). Patient MP triggered thrombin formation, which was reduced compared to the healthy controls (p = 0.008) and strongly inhibited by an anti-factor XII MoAb (two patients), by anti-factor XI MoAb (eight patients) or by anti-TF MoAb (four patients). Concentrations of F1+2 and TAT were elevated (p = 0.005 and p = 0.001, respectively) and correlated inversely with the number of circulating MP (and r = –0.51, p = 0.013, and r = –0.65, p = 0.001, respectively) and their thrombin generation capacity (F1+2: r = –0.62, p = 0.013). Conclusions. In patients with MODS and sepsis relatively low numbers of MP are present that differ from controls in their cellular origin, numbers and coagulation activation mechanisms.

Cell‐derived microparticles in synovial fluid from inflamed arthritic joints support coagulation exclusively via a factor VII–dependent mechanism

“…The generated amount of p-nitroaniline was determined at ϭ 405 nm. To convert the observed optical density (OD) to the thrombin concentration, a reference curve was prepared using purified human thrombin (20).…”

“…In vivo, microparticles can be found in the systemic circulation; their numbers and cellular origin are dependent on the state of health of the individual. Compared with healthy control subjects, patients at risk of thromboembolic complications have elevated numbers of platelet microparticles in their venous blood (12)(13)(14)(15)(16)(17)(18)(19), and we and other investigators have recently demonstrated the presence of microparticles of nonplatelet origin in the circulation of healthy subjects as well as patients with various clinical conditions (17,(20)(21)(22).…”

Vβ‐restricted T cell adherence to endothelial cells: A mechanism for superantigen‐dependent vascular injury

“…Moreover, plasma from patients with APS, MS, or TTP was shown to induce the formation of EMPs from endothelial cells in tissue culture (11,18,19). EMPs exhibit prothrombotic potential, which is mediated by activation of the extrinsic coagulation pathway (i.e., the tissue factor/factor VII-dependent pathway) (11,16,17,(21)(22)(23).…”

Correlations between platelet-derived microvesicles and thrombin generation in patients with coronary artery disease

“…negatively charged phospholipids and tissue factor [1][2][3]. The number of circulating PMV has been shown to increase in various clinical conditions with increased thrombotic risk including coronary artery disease (CAD) [1,4].…”