Treatment of preeclamptic vessels with pravastatin enhances vessel function and alters caveolae form and distribution through removal of cellular cholesterol

Abstract

IntroductionPreeclampsia (PE) causes significant maternal and foetal morbidity and mortality. Maternal vascular endothelial dysfunction contributes to PE resulting in systemic organ dysfunction. Symptoms of PE are most effectively alleviated/managed through pre‐term delivery and/or expectant care, highlighting the need for effective therapies to be identified. The potential clinical applications of pravastatin in the treatment of PE has been reported across multiple studies, however the mechanism(s) behind this is have yet to be elucidated [1, 2].AimsThis study aims to investigate the effect of in vitro pravastatin on uterine microvascular endothelial function in PE, specifically its role in modulating caveolae form and distribution and hence vascular function in PEMethodsMyometrial radial arterioles from caesarean‐section normotensive (NT) and PE patients were incubated with pravastatin (2mM/6h) in vitro. Electron microscopy, immunohistochemistry and pressure myography were used to characterize caveolae and vessel structure and function. Parallel studies conducted with methyl‐β‐cyclodextrin (MβCD) (10mM/1h) examined the effects of removing cholesterol on function.ResultsOverall caveolae density/µm is reduced 24% from 5.5 ± 0.1/µm in NT (n=4, P<0.05) to 4.2 ± 0.01/µm (n=4, P<0.05) in PE vessels, a further 31% to 1.9 ± 0.8/µm (n=4, P<0.05) in PE vessels following treatment with pravastatin. Myoendothelial gap junction density/5mm of vessel length is reduced ~215% from 5.7 ± 1.3/5mm in NT (n=3, P<0.05) to 1.8 ± 0.9/5mm (n=3, P<0.05) in PE vessels. Confocal immunohistochemistry showed decreased caveolin‐1 expression in PE arterioles relative to NT with expression redistributed to endothelial cell borders, following treatment with pravastatin expression was reduced a further ~50% in PE vessels (n=6‐8, P<0.05). Functionally, endothelium‐dependent relaxation was inhibited in arteries from PE compared to NT. Inhibition of NOS/COX reduced bradykinin‐induced dilation in arteries from NT but not PE, suggesting NO/PG‐mediated dilation is lost in PE.. Pravastatin incubation restored endothelium‐dependent relaxation in PE samples to NT levels enhancing the NO and IKCa‐mediated components of relaxation. Incubation with MβCD increased sensitivity (LogEC50 from ‐7.37 to ‐8.24, P<0.05) and maximum dilation to bradykinin in arteries from NT (81.7 ± 4.9.% (n=13) to 94.8 ± 5.2 % (n=8), P<0.05), but had no significant effect in arteries from PE (max 65.6 ± 6.4% (n=17) to 86.5 ± 13.5% (n=3), P>0.05).DiscussionThis data suggests treatment of preeclamptic vessels with pravastatin can be associated with improved vessel function as well as modulation of caveolae form and distribution, specifically though the removal of cellular cholesterol.1. Costantine, M. M. & Cleary, M. K. Obstetrics & Gynecology 121, 349‐353, (2013).2. Esteve‐Valverde, E. et al. Obstetrical & Gynecological Survey 73, 40‐55, (2018).