Sulforaphane improves vascular reactivity in mouse and human arteries after “preeclamptic-like” injury

Highlights

• Sulforaphane protects the vasculature against “pre-eclamptic-like” damage.

• Sulforaphane induces relaxation of resistance arteries from mice and humans.

• Sulforaphane appears to operate independently of endothelial cells by modulating calcium-induced contraction.

Abstract

Introduction

The widespread maternal endothelial dysfunction that underlies the manifestations of preeclampsia is thought to arise from excessive placental production of antiangiogenic factors and enhanced oxidative stress. Therefore, we assessed whether the natural antioxidant sulforaphane could improve vascular function.

Methods

Cell viability of human umbilical vein endothelial cells (HUVECs) was assessed after 24 or 48 h in normoxia (20% O₂) or hypoxia (1% O₂) with or without sulforaphane. To model vascular dysfunction associated with preeclampsia, mouse mesenteric arteries were incubated in trophoblast conditioned media (TCM), and human omental arteries incubated in preeclamptic explant media (PEM) with or without sulforaphane. Both media are rich in antiangiogenic compounds associated with preeclampsia. TCM was generated from primary cytotrophoblast cells from term placentae of normotensive, while PEM was generated from explants from preeclamptic women. Reactivity was assessed by wire myography. sulforaphane's actions as a vasodilator were also investigated.

Results

Under conditions of hypoxia, sulforaphane improved HUVEC viability. In mouse mesenteric arteries, sulforaphane reduced contraction evoked by potassium (p < 0.001), phenylephrine and endothelin 1 (all p < 0.001). Sulforaphane also inhibited Ca²⁺-induced contraction (p = 0.014). Sulforaphane prevented TCM-induced augmentation of phenylephrine and angiotensin II-mediated contraction of mouse mesenteric arteries. In human omental arteries, sulforaphane induced vasodilation (p < 0.001), and prevented PEM-induced endothelial dysfunction by restoring arterial sensitivity to the endothelium-dependent vasodilator bradykinin (p = 0.008).

Discussion

Sulforaphane causes relaxation in arteries and protects against arterial dysfunction induced by placental-derived antiangiogenic factors, which are known to contribute to the preeclampsia.

Introduction

Preeclampsia is a multi-system disorder characterised by new onset hypertension after 20 weeks’ gestation with associated maternal organ dysfunction and/or fetal growth restriction [1]. It remains a leading cause of maternal and perinatal morbidity and mortality worldwide. Though much remains unclear regarding the pathophysiology of preeclampsia, the last twenty years have seen significant advances in our understanding of the disease [2]. Early in pregnancy incomplete spiral artery remodelling results in inadequate blood flow to the placenta and subsequent progressive and sustained hypoxic ischaemic injury throughout pregnancy [3]. The oxidative stress from this insult causes inflammation and excessive placental release of several inflammatory cytokines and vasoactive compounds into maternal circulation [3]. In turn, these compounds, such as soluble fms-like tyrosine kinase-1 (sFlt-1) [4], soluble endoglin [5,6] and activin A [7,8], induce dysfunction of the maternal vascular endothelium [9,10]. As the endothelium becomes damaged, its protective vasodilator influence is compromised and arteries constrict, inducing the hypertension and impaired perfusion of maternal organs, including kidney, liver, heart and brain, characteristic of preeclampsia [11,12]. As such, the second stage of preeclampsia can be considered, in principal, a disease of the maternal vascular endothelium [13].

Understandably, current therapies for preeclampsia are largely focussed on controlling maternal blood pressure [1,14]. The use of antihypertensives in preeclampsia has been responsible for reducing maternal stroke risk and maternal mortality [1,15]. However, the underlying endothelial dysfunction continues largely unabated by antihypertensives, such that the hypertension and end-organ damage eventually become refractory to therapy, and delivery of the baby becomes inevitable [1].

Ideally, the management of preeclampsia would include an approach that improves maternal vascular endothelial health, reduces oxidative stress and promotes vasorelaxation [2,14]. The naturally occurring isothiocyanate antioxidant sulforaphane may offer such an approach. Sulforaphane is a safe and naturally occurring antioxidant found in cruciferous vegetables such as broccoli sprouts and may offer benefit to diseases characterised by oxidative stress. An inducer of the antioxidant pathway nuclear factor erythroid 2 like-2 (NFE2L2) [[16], [17], [18], [19]], sulforaphane shows promise in the treatment of cardiovascular disease outside of pregnancy [[20], [21], [22]]. Early in vitro studies also suggest that it may improve placental mitochondrial function [23], reducing placental oxidative stress that drives placental secretion of vasoactive compounds and the vascular dysfunction that jointly underlie preeclampsia [23]. Here, we aimed to investigate the effects of sulforaphane on human umbilical vein endothelial cell viability and vascular reactivity in rodent mesenteric and human omental arteries.