Shed membrane particles from preeclamptic women generate vascular wall inflammation and blunt vascular contractility

Area of Science:

• Cardiovascular Biology
• Reproductive Medicine
• Pathophysiology

Background:

• Preeclampsia is a multisystemic disorder characterized by vascular dysfunction.
• Microparticles are implicated in various vascular pathologies.
• The specific role of microparticles in preeclampsia-induced vascular dysfunction requires further elucidation.

Purpose of the Study:

• To investigate the role of microparticles in preeclampsia-associated vascular dysfunction.
• To determine the origin and specific contributions of leukocyte- and platelet-derived microparticles.
• To elucidate the molecular mechanisms underlying microparticle-induced vascular hyporeactivity.

Main Methods:

• Analysis of circulating microparticle levels in preeclamptic and healthy pregnant women.
• Ex vivo studies using human omental arteries and mouse aortas treated with microparticles.
• Assessment of vascular reactivity to serotonin in the presence of nitric oxide synthase (NOS) and cyclooxygenase-2 (COX-2) inhibitors.
• Measurement of nitric oxide (NO) and 8-isoprostane production.
• Evaluation of inducible NOS (iNOS) and COX-2 expression, nuclear factor-kappaB (NF-κB) activation, and oxidative/nitrosative stress markers.
• In vivo studies involving administration of preeclamptic microparticles to mice.

Main Results:

• Preeclamptic women exhibit elevated circulating levels of leukocyte- and platelet-derived microparticles.
• Microparticles from preeclamptic pregnancies induce vascular hyporeactivity to serotonin ex vivo.
• This hyporeactivity is linked to increased NO production and reversed by NOS inhibition.
• COX-2 inhibition partially reduces contraction with healthy microparticles but abolishes it with preeclamptic microparticles, associated with increased 8-isoprostane.
• Preeclamptic microparticles upregulate iNOS and COX-2, activate NF-κB, and enhance oxidative/nitrosative stress.
• Leukocyte microparticles mediate the COX-2 vasoconstrictor effect, while platelet microparticles are involved in NO release.
• In vivo administration of preeclamptic microparticles causes vascular hyporeactivity.

Conclusions:

• Preeclamptic microparticles play a significant pathophysiological role in vascular dysfunction.
• They exhibit paradoxical proinflammatory properties, leading to enhanced NO and superoxide anion levels.
• Leukocyte- and platelet-derived microparticles have distinct roles in mediating vascular effects.
• These findings highlight microparticles as potential therapeutic targets in preeclampsia.