Monocyte-Derived Procoagulant Microvesicles Induced by High Glucose Can Be Attenuated by the Antioxidant N-Acetyl-L-Cysteine, Partly Through the P38/MAPK Pathway.

BACKGROUND: Microvesicles (MVs) are small membrane vesicles that are derived from many different cell types by a process of exocytic budding of the plasma membrane. MVs may be associated with a higher incidence of vascular disease in diabetic patients, but the mechanism of this association is unclear. Diabetic patients also show hypercoagulability and platelet hyperaggregability. In this study, we investigated the generation and activity of high glucose (HG)-induced MVs from monocytes to elucidate the potential mechanism of such MVs in diabetes.

METHODS: HG-induced MV generation from THP-1 monocytes before and after N-acetyl-L-cysteine (NAC) treatment was examined by enzyme-linked immunosorbent assay. MV activity was measured by spectrophotometry. Apoptosis and generation of reactive oxidative species (ROS) from THP-1 cells were detected by flow cytometry. Extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and P38/MAPK pathway components were also analyzed in treated monocytes.

RESULTS: MVs were generated from THP-1 cells after 20 hr of exposure to HG (4.6-fold higher than untreated control cells), which was concomitant with a 3.3-fold increase in apoptosis (P < 0.01). The procoagulant activity (PCA) of the generated MVs was increased significantly by 4.1-fold (P < 0.01) relative to untreated cells. ROS levels peaked 2 hr after HG exposure. The frequency of MVs was greatly decreased after NAC treatment (P < 0.01). Both the ERK/MAPK and P38/MAPK pathway were activated after HG stimulation, whereas treatment with a P38 inhibitor decreased MV generation by 66% compared to untreated control.

CONCLUSIONS: The generation of monocyte-derived MVs induced by HG was associated with PCA, concomitant with apoptosis and ROS generation. The P38/MAPK pathway was partly involved in this process as evidenced by the reduction in MV generation following treatment with a P38 inhibitor. Our results could provide insights into novel mechanisms of thrombogenicity in an HG state.