Bioflavonoid luteolin normalizes pathways implicated in preeclampsia vascular dysfunction

Preeclampsia (PE) is a pregnancy disease characterized by maternal hypertension and vascular dysfunction. PE is believed to originate from the ischemic/hypoxic placenta that activate local HIF-1α-mediated release of anti-angiogenic sFlt-1 and release of inflammatory cytokines, such as TNF-α. Signaling from both sFlt-1 and TNF-α-induced NF-κB activation result in upregulation of the potent vasoconstrictor ET-1. Antagonism of ET-1 signaling has been shown to relieve symptoms in animal models of PE, but these treatments are contraindicated in pregnancy. Luteolin is a naturally occurring bioflavonoid that has been studied for its use as an anti-inflammatory and anti-hypertensive agent but has never been studied in PE. In this in vitro study, we tested the hypothesis that luteolin may attenuate pathways involved in vascular dysfunction by attenuating HIF-1α increase (via upstream PI3K and ERK) as well as TNF-α-induced NF-κB activation. To study HIF-1α inhibition by luteolin, placental explants from normotensive patients were treated under normoxic (20%) and hypoxic (2%) conditions with luteolin (10μM) for 72 hours, in the presence and absence of relevant inhibitors; PI3K inhibitor (LY294002, 50μM) and ERK inhibitor (U0126, 20μM). Western blots were used to measure HIF-1α protein changes. HUVEC cells were stimulated by TNF-α in the presence or absence of luteolin to determine NF-κB nuclearization by immunofluorescence.Hypoxic incubations significantly increased HIF-1α compared to normoxia (1.44 + 0.43 vs 0.55 + 0.21 arbitrary units (AU); p<0.001). Although HIF-1α expression remained unchanged regardless of treatment in normoxic samples, hypoxic samples treated with luteolin had a significant reduction of HIF-1α expression (1.44 + 0.43 vs 0.51 + 0.09 AU; p<0.01). Similarly, HIF-1α expression was reduced by PI3K inhibitor treatment in hypoxia (1.44 + 0.43 vs 0.56 + 0.18 AU; p<0.01) and ERK 1/2 inhibitor (1.44 + 0.43 vs 0.66 + 0.24 AU; p<0.05). The combination of luteolin and inhibitors did not result in an additive effect. NF-κB nuclearization increased significantly after stimulation with TNF-α (0.38 + 0.13 vs 1.07 + 0.45 AU; p<0.01), which was ameliorated by luteolin to 0.51 + 0.18 AU (p<0.05).Maternal vascular dysfunction is a final common pathway in the pathogenesis of PE, stimulated by upregulation of ET-1. Signaling by ET-1 is promoted by upregulation of HIF-1α-induced sFlt-1 and TNF-α activation of NF-κB. Luteolin, based on our data, is capable of targeting these pathways of ET-1 upregulation and has the potential to serve as a therapeutic for PE. This work was supported by NIH 1R56HL157579-01. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.