Joey P. Granger

Preeclampsia (PE) is a serious hypertensive complication of pregnancy and is a leading cause of maternal death and major contributor to maternal and perinatal morbidity, including establishment of long‐term complications. The continued prevalence of PE stresses the need for identification of novel treatments which can target prohypertensive factors implicated in the disease pathophysiology, such as soluble fms‐like tyrosine kinase 1 (sFlt‐1). We set out to identify novel compounds to reduce placental sFlt‐1 and determine whether this occurs via hypoxia‐inducible factor (HIF)‐1α inhibition. We utilized a commercially available library of natural compounds to assess their ability to reduce sFlt‐1 release from primary human placental cytotrophoblast cells (CTBs). Human placental explants from normotensive (NT) and preeclamptic (PE) pregnancies were treated with varying concentrations of luteolin. Protein and mRNA expression of sFlt‐1 and upstream mediators were evaluated using ELISA, western blot, and real‐time PCR. Of the natural compounds examined, luteolin showed the most potent inhibition of sFlt‐1 release, with >95% reduction compared to vehicle‐treated. Luteolin significantly inhibited sFlt‐1 in cultured placental explants compared to vehicle‐treated in a dose‐ and time‐dependent manner. Additionally, significant decreases in HIF‐1α expression were observed in luteolin‐treated explants, suggesting a mechanism for sFlt‐1 downregulation. The ability of luteolin to inhibit HIF‐1α may be mediated through the Akt pathway, as inhibitors to Akt and its upstream regulator phosphatidylinositol‐3 kinase (PI3K) resulted in significant HIF‐1α reduction. Luteolin reduces anti‐angiogenic sFlt‐1 through inhibition of HIF‐1α, making it a novel candidate for the treatment of PE.

Preeclampsia (PE) is a disease of hypertension and systemic vasoconstriction during pregnancy. Placental ischemia is implicated in PE by release of pro-hypertensive factors, like soluble Fms-like tyrosine kinase-1 (sFlt-1). Recently, we identified the bioflavonoid, luteolin, as a potent inhibitor of sFlt-1 and hypoxia-inducible factor 1α (HIF-1α, a major positive regulator of sFlt-1) in human placental cell lines and explants. However, the impact of luteolin in models of PE is unknown. We tested the hypothesis that luteolin attenuates placental ischemia-induced hypertension and lowers circulating sFlt-1 levels. Sprague-Dawley rats were started on luteolin treatment at gestational day 14 (20 mg/kg per day) or vehicle (0.5 g peanut butter) as well as placed in Reduced Uterine Perfusion Pressure (RUPP) placental ischemic or Sham surgery groups. The ensuing 4 experimental groups were: Sham+vehicle (N=14), Sham+luteolin (N=15), RUPP+vehicle (N=14), and RUPP+luteolin (N=15). On day 18, rats were implanted with carotid catheters for measurement of conscious mean arterial blood pressure (MAP) on gestational day 19. Luteolin treatment significantly attenuated RUPP-induced rises in maternal MAP (RUPP+vehicle: 118±2 vs. RUPP+luteolin: 108±1 mmHg, P0.05). Circulating levels of sFlt-1 were elevated in RUPP+vehicle: 1.66±0.10 pg/mL vs. Sham+vehicle: 1.01±0.08 pg/mL (P<0.05) that were significantly reduced with luteolin treatment only in RUPP+luteolin: 1.09±0.11 pg/mL and not Sham+luteolin: 1.26±0.11 pg/mL (P<0.05). Total fetal weight was lower in RUPP+vehicle: 14±2 g vs. Sham+vehicle: 26±2 g (P0.05). Total placental weight was less in RUPP+vehicle: 3.3±0.6 g vs. Sham+vehicle: 6.4±0.4 g (P0.05). Overall, luteolin significantly attenuated placental ischemia-induced hypertension and reduced circulating sFlt-1 levels suggesting that naturally occurring flavonoids can be developed as therapeutics 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 Physiology was not involved in the peer review process.

Mediators of cardiac injury in preeclampsia are not well understood. Preeclamptic women have decreased cardiac global longitudinal strain (GLS), a sensitive measure of systolic function that indicates fibrosis and tissue injury. GLS is worse in preeclampsia compared to gestational hypertension, despite comparable blood pressure, suggesting that placental factors may be involved. We previously showed that Activin A, a pro-fibrotic factor produced in excess by the placenta in preeclampsia, predicts impaired GLS postpartum. Here, we hypothesized that chronic excess levels of Activin A during pregnancy induces cardiac dysfunction. Rats were assigned to sham or activin A infusion (1.25–6 µg/day) on a gestational day (GD) 14 (n = 6–10/group). All animals underwent blood pressure measurement and comprehensive echocardiography followed by euthanasia and the collection of tissue samples on GD 19. Increased circulating activin A (sham: 0.59 ± 0.05 ng/mL, 6 µg/day: 2.8 ± 0.41 ng/mL, p < 0.01) was associated with impaired GLS (Sham: −22.1 ± 0.8%, 6 µg/day: −14.7 ± 1.14%, p < 0.01). Activin A infusion (6 µg/day) increased beta-myosin heavy chain expression in heart tissue, indicating cardiac injury. In summary, our findings indicate that increasing levels of activin A during pregnancy induces cardiac dysfunction and supports the concept that activin A may serve as a possible mediator of PE-induced cardiac dysfunction.

In this review, we first provide a brief overview of the nitric oxide synthase (NOS) isoforms and biochemistry. This is followed by describing what is known about NOS-mediated blood pressure control during normal pregnancy. Circulating nitric oxide (NO) bioavailability has been assessed by measuring its metabolites, nitrite (NO₂) and/or nitrate (NO₃), and shown to rise throughout normal pregnancy in humans and rats and decline postpartum. In contrast, placental malperfusion/ischemia leads to systemic reductions in NO bioavailability leading to maternal endothelial and vascular dysfunction with subsequent development of hypertension in PE. We end this article by describing emergent risk factors for placental malperfusion and ischemic disease and discussing strategies to target the NOS system therapeutically to increase NO bioavailability in preeclamptic patients. Throughout this discussion, we highlight the critical importance that experimental animal studies have played in our current understanding of NOS biology in normal pregnancy and their use in finding novel ways to preserve this signaling pathway to prevent the development, treat symptoms, or reduce the severity of PE.

Preeclampsia (PE), a hypertensive disorder, occurs in 3% to 8% of pregnancies in the United States and affects over 200,000 women and newborns per year. The United States has seen a 25% increase in the incidence of PE, largely owing to increases in risk factors, including obesity and cardiovascular disease. Although the etiology of PE is not clear, it is believed that impaired spiral artery remodeling of the placenta reduces perfusion, leading to placental ischemia. Subsequently, the ischemic placenta releases antiangiogenic and pro‐inflammatory factors, such as cytokines, reactive oxygen species, and the angiotensin II type 1 receptor autoantibody (AT1‐AA), among others, into the maternal circulation. These factors cause widespread endothelial activation, upregulation of the endothelin system, and vasoconstriction. In turn, these changes affect the function of multiple organ systems including the kidneys, brain, liver, and heart. Despite extensive research into the pathophysiology of PE, the only treatment option remains early delivery of the baby and importantly, the placenta. While premature delivery is effective in ameliorating immediate risk to the mother, mounting evidence suggests that PE increases risk of cardiovascular disease later in life for both mother and baby. Notably, these women are at increased risk of hypertension, heart disease, and stroke, while offspring are at risk of obesity, hypertension, and neurological disease, among other complications, later in life. This article aims to discuss the current understanding of the diagnosis and pathophysiology of PE, as well as associated organ damage, maternal and fetal outcomes, and potential therapeutic avenues. © 2021 American Physiological Society. Compr Physiol 11:1315‐1349, 2021.

Degenerin proteins, such as the beta epithelial Na⁺ channel (βENaC), are essential in the intracellular signaling of pressure-induced constriction, an important vascular smooth muscle cell (VSMC) function. While certain cytokines reduce ENaC protein in epithelial tissue, it is unknown if interleukin-17 (IL-17), a potent pro-inflammatory cytokine, directly mediates changes in membrane-associated βENaC in VSMCs. Therefore, we tested the hypothesis that exposure to IL-17 reduces βENaC in VSMCs through canonical mitogen-activated protein kinase (MAPK) signaling pathways. We treated cultured rat VSMCs (A10 cell line) with IL-17 (1–100 ng/mL) for 15 min to 16 h and measured expression of βENaC, p38MAPK, c-jun kinase (JNK), and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB). IL-17 reduced βENaC protein expression in a concentration-dependent fashion and increased phosphorylation of p38MAPK by 15 min and JNK by 8 h. NFκB was unaffected by IL-17 in VSMCs. IL-17 treatment reduced VSMC viability but had no effect on cell death. To determine the underlying signaling pathway involved in this response, VSMCs were treated before and during IL-17 exposure with p38MAPK or JNK inhibitors. We found that JNK blockade prevented IL-17-mediated βENaC protein suppression. These data demonstrate that the pro-inflammatory cytokine IL-17 regulates VSMC βENaC via canonical MAPK signaling pathways, raising the possibility that βENaC-mediated loss of VSMC function may occur in inflammatory disorders.