Key result
Endothelial microparticles produced reactive oxygen species via Nox subunits, increasing superoxide and decreasing nitric oxide production in cultured endothelial cells.
Endothelial microparticles directly produce reactive oxygen species via NADPH oxidase, which alters endothelial nitric oxide production but does not fully account for eMP-induced impairment in vasorelaxation.
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eMP-derived ROS may impair endothelial NO in vitro; leaves open in vivo relevance and therapeutic targeting.
Endothelial microparticles are effectors of endothelial damage; however mechanisms involved are unclear. We examined the effects of eMPs on cultured endothelial cells (ECs) and isolated vessels and investigated the role of eMP-derived reactive oxygen species (ROS) and redox signaling in these processes. eMPs were isolated from EC media and their ability to directly produce ROS was assessed by lucigenin and liquid chromatography. Nicotinamide adenine dinucleotide phosphate oxidase (Nox) subunits were probed by Western blot. ECs were treated with eMPs and effects on kinase signaling, superoxide anion (O2 (∙-)) generation, and nitric oxide (NO) production were examined. Acetylcholine-mediated vasorelaxation was assessed by myography in eMP-treated mesenteric arteries. eMPs contained Nox1, Nox2, Nox4, p47(phox), p67(phox), and p22(phox) and they produced ROS which was inhibited by the Nox inhibitor, apocynin. eMPs increased phosphorylation of ERK1/2 and Src, increased O2 (∙-) production, and decreased A23187-induced NO production in ECs. Pretreatment of eMPs with apocynin diminished eMP-mediated effects on ROS and NO production but had no effect on eMP-mediated kinase activation or impairment in vasorelaxation. Our findings identify a novel mechanism whereby eMP-derived ROS contributes to MP bioactivity. These interactions may be important in conditions associated with vascular injury and increased eMP formation.
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Burger et al. (2016) studied Endothelial damage and vascular injury. Endothelial microparticles (eMPs) vs. Apocynin pretreatment / untreated cells was evaluated on ROS production, kinase signaling, NO production, and vasorelaxation. Endothelial microparticles produced reactive oxygen species via Nox subunits, increasing superoxide and decreasing nitric oxide production in cultured endothelial cells.
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