Mutations in CYP4F2 (rs2108622) and CYP4A11 (rs1126742) that inhibit the production of 20-HETE have been linked to hypertension in human genetic studies. We confirmed that these same variants are associated with hypertension and cognitive dysfunction in 4,286 elderly subjects in the Atherosclerosis Risk in Communities Neurocognitive Study . These studies establish that mutations in CYP enzymes that reduce 20-HETE promote hypertension, but the mechanisms remain controversial since 20-HETE has both pro- and antihypertensive actions. To address this question, we identified a homologous genetic deficiency in the formation of 20-HETE in Dahl S (SS) rats and created SS.5 BN consomic and CYP4A transgenic SS rats to restore CYP4A expression and 20-HETE production, and CYP4A2 and CYP4A3 KO rats on the rescued SS.5 BN background. Mean arterial pressure (MAP), renal and cerebral blood flow, proteinuria, and renal injury were compared in SS versus SS.5 BN and CYP4A transgenic SS rats and in SS.5 BN versus CYP4A2 and CYP4A3 KO rats. MAP increased from 117±2 to 158±5 mmHg (n=34) in SS rats fed a high salt (HS) diet for 3 weeks. Proteinuria rose from 50±4 to 403±30 mg/day. MAP increased less, from 108 + 5 to 133 + 5 mmHg (n=7) in CYP4A1 transgenic SS rats and from 109 + 2 to 132 + 2 mmHg (n=23) in SS.5 BN rats. Proteinuria (141±15 and 169±11 mg/day), glomerular injury, and renal fibrosis were all significantly reduced in the CYP4A transgenic and SS.5 BN rats compared to SS rats. KO of CYP4A2 had no effect on MAP (134 + 2 mmHg, n=23) or proteinuria (248 + 23 mg/day) relative to SS.5 BN rats fed an HS diet for 3 weeks. In contrast, MAP and proteinuria were elevated to 148 + 3 mmHg and 350 + 23 mg/day in CYP4A3 KO rats (n=23). The myogenic response of renal and cerebral arteries and autoregulation of RBF and CBF were impaired in SS and CYP4A3 KO rats but were intact in CYP4A transgenic SS rats, SS.5 BN and CYP4A2 KO rats. These findings indicate that a deficiency in the formation of 20-HETE that impairs the myogenic response of renal and cerebral arteries, autoregulation of RBF and CBF, and increases glomerular capillary pressure, promotes the development of hypertension, proteinuria, and renal injury in genetically susceptible individuals and SS rats.

Diabetes, hypertension, and aging are major contributors to cardiovascular and chronic kidney disease (CKD). Sodium/glucose cotransporter 2 (SGLT2) inhibitors have become a preferred treatment for type II diabetic patients since they have cardiorenal protective effects. However, most elderly diabetic patients also have hypertension, and the effects of SGLT2 inhibitors have not been studied in hypertensive diabetic patients or animal models. The present study examined if controlling hyperglycemia with empagliflozin, or given in combination with lisinopril, slows the progression of renal injury in hypertensive diabetic rats. Studies were performed using hypertensive streptozotocin-induced type 1 diabetic Dahl salt-sensitive (STZ-SS) rats and in deoxycorticosterone-salt hypertensive type 2 diabetic nephropathy (T2DN) rats. Administration of empagliflozin alone or in combination with lisinopril reduced blood glucose, proteinuria, glomerular injury, and renal fibrosis in STZ-SS rats without altering renal blood flow (RBF) or glomerular filtration rate (GFR). Blood pressure and renal hypertrophy were also reduced in rats treated with empagliflozin and lisinopril. Administration of empagliflozin alone or in combination with lisinopril lowered blood glucose, glomerulosclerosis, and renal fibrosis but had no effect on blood pressure, kidney weight, or proteinuria in hypertensive T2DN rats. RBF was not altered in any of the treatment groups, and GFR was elevated in empagliflozin-treated hypertensive T2DN rats. These results indicate that empagliflozin is highly effective in controlling blood glucose levels and slows the progression of renal injury in both hypertensive type 1 and type 2 diabetic rats, especially when given in combination with lisinopril to lower blood pressure.

Dahl SS rats rapidly develop hypertension, proteinuria, and renal injury when challenged with a high‐salt diet. Previous studies revealed that a deficiency in the renal formation of 20‐HETE in SS rats impairs afferent arteriole myogenic response, autoregulation of renal blood flow, tubuloglomerular feedback and glomerular capillary pressure and enhances sodium transport in the thick ascending loop of Henle. However, the role of 20‐HETE in podocyte and glomerular barrier function is still unknown. The aim of this study is to investigate the role of 20‐HETE on the regulation of glomerular function and podocyte function using SS rats and CYP4A1 transgenic rats on a SS background. We found that the production of 20‐HETE was significantly higher in the isolated glomeruli of CYP4A1 compared to SS rats by using mass spectrometry. Immunoblot analysis demonstrated that the expression of α‐smooth muscle actin and vimentin was lower in the isolated glomeruli of CYP4A1 vs. SS rats, indicating reduced epithelial mesenchymal transition (EMT). After challenged with a 4% high‐salt diet, the mean arterial pressure increased to a similar extent in both strains as measured by radio telemetry. However, compared with SS rats, CYP4A1 rats developed lower proteinuria (127 ± 14 vs. 270 ± 23 mg/day, respectively), had unaltered glomerular permeability to albumin (Palb) by using a fluorescence dilution technique, and exhibited greater increases in Palb after treatment with HET0016, a 20‐HETE synthesis inhibitor. In addition, Masson's trichrome staining showed that the glomerular injury score was attenuated in hypertensive CYP4A1 transgenic vs. SS rats (1.3 ± 0.2 vs. 2.4 ± 0.2, respectively), and the area of renal interstitial fibrosis was significantly lower in CYP4A1 transgenic vs. SS rats (6% ± 1% vs. 18% ± 4%, respectively). Moreover, hypertensive CYP4A1 rats exhibited less podocyte foot process effacement and detachment than SS rats when examined by a transmission electron microscopy. These findings indicate that increased production of 20‐HETE has renoprotective effects in association with decreased EMT, preserved podocyte and glomerular barrier function. This study indicates that 20‐HETE is a potential novel pharmacological target and biomarker in hypertension and chronic kidney disease.Support or Funding InformationThis study was supported by grants HL36279 (RJR) and DK104184 (RJR), AG050049 (FF), P20GM104357 (RJR and FF) from the National Institutes of Health; 16GRNT31200036 (FF) from the American Heart Association.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Few studies exist on cytochrome P450 (CYP450) metabolites of arachidonic acid (AA) pertaining to the pathophysiological events in pregnancy. We hypothesized that metabolism of AA via the CYP450 pathways is altered within the placenta in women with preeclampsia (PE) and contributes to the pathophysiology of the disease. Thus, placental vascular CYP450 enzyme expression and activity were measured in normal pregnant (NP) and preeclamptic (PE) patients. CYP450 isoform expression (CYP4A11, CYP4A22, CYP4F2, and CYP4F3) was found to be elevated within the placenta of women with PE compared to normal pregnant (NP) women and chronic hypertensive (CHTN) pregnant women. In addition, placental production of 20-HETE was significantly increased in PE women compared to both NP and CHTN women. Moreover, there was an imbalance in circulating 20-HETE:EETs in PE women. To examine whether alterations in CYP450 AA metabolism contribute to the altered placentation in PE, trophoblast function, proliferation and migration were assessed in the presence of exogenous 20-HETE and a 20-HETE specific synthesis inhibitor, HET0016. Trophoblast proliferation was significantly increased in the presence of 20-HETE (1 μM) and reduced with 20-HETE blockade by HET0016 (1 mM, 5 mM, and 10 mM). On the contrary, administration of exogenous 20-HETE (1 μM) significantly reduced trophoblast migration. In conclusion, metabolism of AA via CYP450 is altered in PE, and increased placental production of 20-HETE may contribute to the pathophysiology of the disease.

Recent data suggests cytochrome P450 (CYP450) vasoactive eicosanoids in the pathophysiology of preeclampsia. Thus, we investigated whether alterations in CYP450 expression and 20‐HETE production contribute to maternal hypertension during pregnancy. In order to address this hypothesis, we utilized a newly characterized model of hypertension during pregnancy also documented to have a genetic deficiency in 20‐HETE production, the Dahl S rat. In addition, we utilized a CYP4A1 overexpression transgenic rat. Mean arterial pressure, measured via telemetry, and proteinuria were measured in 12 week old Spraque Dawley (SD), Dahl SSJr, and CYP4A1 Tg rats at baseline, prior to pregnancy, and gestational day (GD) 5, 12, and 19. Consistent with previous reports, a reduction in MAP at term during normal pregnancy was not seen in the Dahl S rat (1.5±6 mmHg, p<0.05; SD, 14±1 mmHg; CYP4A1 Tg, 18±2 mmHg). Proteinuria was elevated in both Dahl SSJr (107±45 mg/day, p<0.05) and CYP4A1 Tg (53±5 mg/day, p<0.05) rats relative to SD (10±1 mg/day) pregnant rats on GD19. Pup number was reduced in the Dahl S (9±1, p<0.05) and increased in the CYP4A1 Tg (11±1, ns) rat compared to the SD (12±1), with no differences noted in placenta to pup weight. CYP450 enzymatic activity, as measured by production of 20‐HETE, within the placenta and kidney were significantly increased in the placenta (0.002±0.0006 vs 0.4±0.2 pmol/min/mg protein) and kidney of CYP4A1 Tg rats (4.4±0.5 vs 1.9±0.7 pmol/min/mg protein). Therefore, alterations in CYP450 enzyme activity and 20‐HETE may contribute to the increases in MAP during pregnancy and may be a potential therapeutic target in the treatment of preeclampsia.Support or Funding Information14SDG20160020; HL121042

We recently reported that zinc‐finger nuclease knockout (KO) of dual‐specificity protein phosphatase‐5 (Dusp5) enhances the myogenic response and autoregulation of cerebral blood flow in FHH.1 BN rats. We identified 4 single nucleotide polymorphisms in Dusp5 in FHH as compared with BN rats, two of which alter CpG sites and another one causes G155R mutation. In the present study, we evaluated whether Dusp5 also plays a role in the regulation of autoregulation of renal blood flow and renal function in a Dusp5 knockout (KO) rat in the FHH.1 BN genetic background, which an 11 bp frame‐shift deletion is introduced by zinc‐finger nuclease and a premature stop codon at AA 121 of Dusp5 protein is produced. The expression of Dusp5 was lower in FHH and in Dusp5 KO rats in comparison to the FHH.1 BN rats. The level of phosphorylated ERK1/2 (p‐ERK1/2), a substrate of Dusp5, was enhanced in the KO rats. The blood pressure and urinary protein excretion was similar in Dusp5 KO (n = 43) and FHH.1 BN rats (n = 30) when they were at 12‐week of age (114 ± 2 vs. 115 ± 1 mmHg and 32 ± 2 vs. 29 ± 3 mg/day). In response to an elevation in pressure from 60 to 120 mm Hg, the renal afferent arterioles (Af‐arts) constricted by 29 ± 2% and 11 ± 1%, and the vascular tone was increased to 36 ± 2% vs 19 ± 1%, respectively in Dusp5 KO (n = 6) in comparison to FHH.1 BN rats (n = 17). Blood pressure was 169 ± 5 vs. 177 ± 5 mmHg in Dusp5 KO (n = 11) vs. FHH.1 BN rats (n = 14) after 3‐week DOCA‐salt treatment. However, proteinuria was significantly reduced in Dusp5 KO rats (258 ± 22 mg/day, n = 12) in comparison to FHH.1 BN rats (338 ± 30 mg/day, n = 12) with the same treatment. The renal injury induced by DOCA‐salt was markedly reduced in Dusp5 KO vs. FHH.1 BN rats as the glomerular injury scores were 2.49 ± 0.03 vs. 2.54 ± 0.01; the areas of renal fibrosis were 5.5 ± 0.5% vs. 8.3 ± 0.3%; the areas of renal protein casts were 0.5 ± 0.2% vs. 2.4 ± 1.0% and renal arteriolar media‐to‐lumen ratios were 0.64 ± 0.03 vs. 0.81 ± 0.04, respectively. These results indicate that Dusp5 modulates myogenic reactivity in the renal circulation and protects against DOCA‐salt hypertension induced chronic renal injury. It supports the view that upregulation of the expression of Dusp5 and/or an activating mutation in Dusp5 may contribute to the impaired myogenic response and autoregulation of renal blood flow and promote the development of chronic renal injury in FHH rats. Support or Funding Information This study was supported by grants HL36279 (RJR) and DK104184 (RJR), AG050049 (FF), P20GM104357 (RJR, FF and JMW) from the National Institutes of Health; 16GRNT31200036 (FF) and 12SDG9440034 (JMW) from the American Heart Association. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Little is currently known of the role(s) of the vasoconstrictor 20-hydroxyeicosatetraenoic acid (20-HETE) in hypertensive pregnancies. We hypothesized that specific inhibition of 20-HETE would attenuate increases in blood pressure in the reduced uterine perfusion pressure (RUPP) rat model of preeclampsia. Specific 20-HETE synthesis inhibitor HET0016 (1 mg/kg) was administered daily to RUPP rats from gestational days 14-18. Blood pressure (BP) increased in RUPP rats and was decreased with HET0016 administration. BP was unchanged in NP + HET0016 rats. Fetal death greatly increased in RUPP rats and was reduced in RUPP + HET0016 rats. 20-HETE levels increased modestly in RUPP rats compared to NP and was reduced in both NP + HET0016 and RUPP + HET0016 rats. Furthermore, circulating levels of HETEs, EET, and DHETE were significantly altered between groups. HET0016 shifted CYP metabolism toward EETs, as indicated by a decrease in plasma 20-HETE:EETs in RUPP + HET0016 rats compared to RUPP. In conclusion, 20-HETE inhibition in RUPP rats reduces BP and fetal death, and is associated with an increase in EET/20-HETE ratio.

We recently identified 4 single nucleotide polymorphisms in Dusp5 in FHH as compared with Brown-Norway (BN) rats, two of which alter CpG sites and another one causes G155R mutation. We then created a Dusp5 knockout (KO) rat in the FHH.1 BN genetic background, in which a small region in Chr. 1 of BN rats containing 15 genes, including Dusp5 into the FHH rats. We found that knockout of Dusp5 enhances the myogenic response and autoregulation of cerebral circulation. In the present study, we evaluated whether Dusp5 also plays a role in the regulation renal function. The expression of Dusp5 was lower in FHH. 1 BN . Dusp5 KO rats in comparison to the FHH.1 BN rats. The levels of p-PKC and p-ERK1/2 were elevated in Dusp5 KO vs. FHH.1 BN rats. The blood pressure and urinary protein excretion was similar in FHH. 1 BN . Dusp5 KO (n = 43) and FHH.1 BN rats (n = 30) when they were at 12-week of age (114 ± 2 vs. 115 ± 1 mmHg and 32 ± 2 vs. 29 ± 3 mg/day). The autoregulation of RBF was similar in FHH.1 BN (n=22) and Dusp5 KO (n = 9) rats in response to elevation of MAP from 100 to 140 mmHg, but was impaired in FHH rats (n=21) that increased by 37.3 ± 2.3% when they were at 12-week of age. In response to an elevation in pressure from 60 to 120 mm Hg, the renal afferent arterioles constricted by 29 ± 2% and 11 ± 1%, respectively in Dusp5 KO (n = 6) in comparison to FHH.1 BN rats (n = 17). Blood pressure was similar in Dusp5 KO (n = 11) vs. FHH.1 BN rats (n = 14) after 3-week DOCA-salt treatment (169 ± 5 vs. 177 ± 5 mmHg). However, proteinuria was significantly reduced in Dusp5 KO rats (258 ± 22 mg/day, n = 12) in comparison to FHH.1 BN rats (338 ± 30 mg/day, n = 12). The renal injury induced by DOCA-salt was markedly reduced in Dusp5 KO vs. FHH.1 BN rats as the glomerular injury scores were 2.49 ± 0.03 vs. 2.54 ± 0.01; the areas of renal fibrosis were 5.5 ± 0.5% vs. 8.3 ± 0.3%; the areas of renal protein casts were 0.5 ± 0.2% vs. 2.4 ± 1.0% and renal arteriolar media-to-lumen ratios were 0.64 ± 0.03 vs. 0.81 ± 0.04, respectively. These results indicate that KO of Dusp5 enhances renal vascular function to protect against DOCA-salt hypertension induced chronic renal injury via activation of PKC/ERK signaling pathway. In conclusion, an activating mutation in Dusp5 may contribute to the impaired myogenic response and promote the development of chronic renal injury in FHH rats.

Few studies exist on cytochrome P450 (CYP450) metabolites of arachidonic acid (AA) pertaining to the pathophysiological events in pregnancy. Therefore, the goal of this study was to determine a role for 20‐Hydroxyeicosatrienoic acid (20‐HETE), a metabolite of the CYP450 enzyme, in trophoblast proliferation, migration, and hypertension during preeclampsia. Placental vascular CYP450 enzymatic activity and circulating eicosanoids were measured in normal pregnant (NP) and preeclamptic (PreE) patients. To determine a role for 20‐HETE on blood pressure we evaluated the effect of a 20‐HETE synthesis inhibitor, HET0016, on mean arterial pressure (MAP) in NP rats and the reduced uterine perfusion pressure (RUPP) rat model of PreE. PreE women displayed increased placenta 20‐HETE (0.1914 ± 0.025 pmol/min/mg, n=5, p<0.05) compared to NP women (0.1192 ± 0.017 pmol/min/mg, n=7) and increased ratio of circulating 20‐HETE:EETs compared to NP women (p<0.05). Importantly the increase in MAP in response to RUPP in rats (122 ± 3 mmHg) was attenuated with 20‐HETE blockade (112 ± 2 mmHg, p<0.05). To examine the role for CYP450 metabolites in trophoblast function, proliferation and migration assays were performed in the presence of exogenous 20‐HETE and HET0016. Trophoblast proliferation was increased with 20‐HETE (46%, p<0.05) and reduced with 20‐HETE blockade by HET0016 (75%, p<0.05). However, administration of exogenous 20‐HETE decreased trophoblast migration evaluated by scratch assay (p<0.05). In conclusion, alterations in the metabolism of AA, specifically increases in 20‐HETE, may contribute to pathophysiology of Pre by reducing trophoblast cell migration and causing hypertension in response to placental ischemia.Support or Funding Information14SDG20160020, 2RO1HD067541

It is well documented that a sexual dimorphism exists in the regulation of blood pressure in both the human population as well as experimental animal models, however evidence of a sex difference is lacking in the Dahl S rat. Thus, we hypothesize that alterations in CYP450 expression and 20-HETE production contribute to the progression of renal injury in Dahl S rats. Consistent with what we have previously reported, no difference was noted in the blood pressure of male or female Dahl SSJr rat (213.8±12 vs 196.8±13 mmHg, ns) following 4 weeks of a high salt diet (8%NaCl). However, proteinuria (148±25 vs 355±22 mg/day, p<0.05) and renal injury (1.9±0.01 vs 2.5±0.2) were lower in female relative to male rats. In addition, GFR was significantly reduced in male vs female rats (392.4±89 vs 829.5±98 μl/min/g, p<0.05) following at high salt challenge. Renal cortical (11.3.8±16 vs 20.99±2.8 pmol/min/mg, p<0.05) and outer medullary (19.4±3 vs 6.9±1.8 pmol/min/mg, p<0.05) 20-HETE production was elevated in female versus male rats. Furthermore, renal vascular 20-HETE production was elevated in the renal vessels compared to males (0.53±0.23 vs 3.2±1.2 pmol/min/mg, p<0.05). Thus, alterations in the production of renal eicosanoids may contribute to the delay in renal injury in females relative to male Dahl SSJr rats. AHA 14SDG20160020

Preeclampsia (PreE) results from an impaired vascular remodeling of the placental spiral arteries. Recent data suggests cytochromeP450 (CYP450) vasoactive eicosanoids in the etiology of the disease. Therefore, we investigated whether CYP450 expression and 20‐HETE production are elevated in preeclamptic populations and if 20‐HETE plays a role in hypertension and trophoblast migration. CYP450 enzymatic activity and circulating eicosanoids were measured in normal pregnant (NP) and PreE patients by LC/MS. In addition, the proliferative actions of 20‐HETE, a major CYP450 metabolite were investigated in an in vivo model of trophoblast syncytialisation. PreE women displayed a significant increase in CYP450 enzyme expression and 20‐HETE production relative to NP women (0.192±0.04 vs 0.119±0.06 pg/min/mg, p<0.05). Circulating 20‐HETE:EETs were statistically increased in women with PreE (1.4±0.5 vs 0.1± 0.04 mg/ml, p<0.05). BeWo cell cultures displayed an increase (45%, p<0.05) in proliferation in response to exogenous 20‐HETE (1μM), while inhibition of endogenous 20‐HETE with 17‐ODYA (10uM) and HET0016 (1nM) displayed a 10% (ns) and 75% (p<0.05) inhibition. Moreover, trophoblast migration and invasion were decreased in the presence of exogenous 20‐HETE (1μM, p<0.05). Therefore, alterations in CYP450 enzyme activity and 20‐HETE may contribute to the altered vascular remodeling seen in women PreE. Support or Funding Information American Heart Association 14SDG20160020

While soluble fms‐like tyrosine‐1 (sFlt‐1) is implicated in the pathogenesis of hypertension during preeclampsia, the mechanisms leading to the enhanced sFlt‐1 production remain unclear. A recent report suggests exogenous angiotensin II (ANGII) stimulates sFlt‐1 production in pregnant rats, however, the role of endogenous ANGII in mediating the placental production of sFlt‐1 in response to placental ischemia remains unknown. Therefore, the purpose of this study was to determine the role of endogenous ANGII in mediating the placental production of sFlt‐1 in response to placental ischemia in pregnant Sprague–Dawley rats. To this end we compared sFlt‐1 and ANGII levels from placental explants collected from normal pregnant (NP) and Reduced Uterine Perfusion Pressure (RUPP) rats. sFlt‐1 (3271 ± 264 vs. 2228 ± 324 pg/mL, P < 0.05) and ANGII levels (43.2 ± 2.8 vs. 26.7 ± 1.9 pg/mL, P < 0.05) were higher in placental explants from RUPP rats versus NP rats. Administration of Losartan, an angiotensin type 1 (AT1) receptor antagonist, (10 mg/day for 5 days) to RUPP rats significantly reduced plasma levels of sFlt‐1 (1432 ± 255 pg/mL, P < 0.05) when compared with untreated control rats (3431 ± 454 pg/mL). In addition, RUPP‐induced hypertension was significantly reduced (113 ± 2 mmHg vs. 139 ± 2 mmHg, P < 0.05). In conclusion, placental sFlt‐1 and ANGII production are significantly elevated in response to placental ischemia in pregnant rats. In addition, AT1 receptor activation, by endogenous ANGII, appears to play an important role in mediating the placental production of sFlt‐1 in response to placental ischemia in pregnant rats.

Preeclampsia (PreE) is thought to originate from an impaired vascular remodeling of the placental spiral arteries. Recent data suggests a possible role of cytochromeP450 (CYP450) vasoactive eicosanoids in the etiology of the disease. We tested the hypothesis that alterations in the profile of arachidonic acid (AA) metabolites of the CYP450 pathway may contribute to the impaired vascular remodeling in preeclampsia. Proliferation of BeWo cells, an in vivo model of trophoblast syncytialisation, was measured in the presence of 20-HETE, the major CYP450 metabolite, and 17-ODYA, a mechanism-based suicide substrate CYP450 inhibitor, in order to determine the proliferative actions of 20-HETE. In addition, microsomes were isolated from placental vessels of normal pregnant (NP) and PreE women and CYP450 enzyme activity was determined by HPLC/mass spectrometry. Incubation of BeWo cells with 10 nM, 100 nM, and 1 μM of 20-HETE displayed a dose-dependent increase in cell proliferation with an approximate 40% increase at 1 μM, while inhibition of 20-HETE with 17-ODYA (10 μM) displayed a 40% decrease in BeWo cell proliferation. Placental vascular microsomes isolated from PreE women displayed a significant increase in 20-HETE production relative to NP women. 15-HETE, 12-HETE, and total HETE production were also increased in PreE compared to NP. Increases in 20-HETE production promote, while inhibition of 20-HETE reduces proliferation of trophoblasts in vitro. Increases in the production of an endogenous inhibitor of 20-HETE, such as15-HETE, may contribute to the reduced trophoblast invasion and impaired vascular remodeling seen in PreE. N. Lee: None. S. Spencer: None. B.B. LaMarca: None. S. Murphy: None.

Preeclampsia, the development of new onset hypertension and proteinuria during pregnancy, affects approximate to 3 - 8% of all pregnancies and is a leading cause of maternal and perinatal morbidity and mortality. Despite the potentially devastating effects of this disease on the mother and the baby and the recent advances in understanding some of the pathological mechanisms responsible for the progression of preeclampsia, there are still few therapies available to manage the disease. The maternal syndrome of preeclampsia is characterized by systemic endothelial dysfunction; therefore, agents that improve endothelial function may hold promise to alleviate the symptoms of preeclampsia, delay the necessity for preterm delivery and improve neonatal outcomes. This brief review will focus on two therapies that are already approved for use in the US for other indications: PDE-5 inhibition to preserve nitric oxide - cGMP signaling to promote vasodilation and inhibition of the endothelin type A receptor to reduce vascular contraction.

Preeclampsia (PE) is a hypertensive disorder of pregnancy afflicting 5-10% of US pregnancies. Recent data suggests the vasoactive cytochromeP450 metabolite, 20-hydroxyeicosatetraenoic (20-HETE), may play a role in hypertension in response to placental ischemia. Thus, we hypothesized that administration of HET0016, a specific 20-HETE synthesis inhibitor, would improve the pathophysiology in the reduced uterine perfusion pressure (RUPP) rat model of placental ischemia. RUPP procedure was performed on gestational day (GD) 14 and HET0016 (1mg/kg, i.p) was administered on GD14-18. Uterine Artery Resistance Index (UARI) was measured via sonography on GD18 and blood pressure (MAP) was measured on day GD19. UARI increased in RUPP compared to NP rats (0.71±0.04 vs 0.60 ±0.02), and was reduced in RUPP+HET0016 treated animals (0.56±0.07). Pup reabsorption (% of total pups at GD19) was significantly increased in RUPP versus NP rats (58±6 vs 7±6%, P<0.05). Treatment with HET0016 significantly reduced pup resorption in RUPP+HET0016 rats relative to control (21±7%, P<0.05). MAP was elevated in RUPP rats compared to NP rats (122±3 vs 104±3 mmHg, P<0.05), and was significantly decreased upon administration of HET0016 (112 ±3 mmHg, P<0.05). MAP remained unchanged in NP+HET0016 rats (106±5 mmHg). In conclusion, inhibition of 20-HETE synthesis prevented increases in UARI, fetal reabsorption, and blood pressure in the RUPP rat model of PE, thereby improving the pathology associated with hypertension in response to placental ischemia.

It is well documented that a sexual dimorphism exists in the regulation of blood pressure in both the human population as well as experimental animal models, such that males have higher blood pressures than females of the same age. While there is a clear disparity in the development of hypertension and progression of renal injury in many rodent models, evidence of a sex difference is lacking in the Dahl S rat. While the current reports present conflicting data, we hypothesize that alterations in CYP450 expression and 20-HETE production contributes to the relative resistance of female Dahl S rats to target organ damage compared to males. Consistent to what we have previously reported, the time course for the development of proteinuria and renal injury were significantly reduced in female Dahl SSJr rats challenged with a high salt diet relative to male rats. In addition, renal cortical 20-HETE production was elevated in female (120.8±4.2 pmol/min/mg) versus male rats (45.1±11.78 pmol/min/mg), while no difference was noted in the outer medulla (19.6±1.8 vs 17.15± 3.9 pmol/min/mg). Introgression of the CYP4A1 gene into the Dahl S genetic background, resulted in significant elevations in 20-HETE production both on low salt and high salt diets. Furthermore the rise in mean arterial pressure was attenuated in CYP4A1 overexpressing rats in both sexes (Δ19mmHg in CYP females vs 61mmg in Dahl S females; 20mmHg in CYP males vs 50mmHg in Dahl S males). Moreover, the degree of glomerular injury was reduced in CYP rats, both male and female, compared to Dahl S rats in response to a high salt diet. Therefore, increases in the CYP gene expression and 20-HETE production prevent the rise in mean arterial pressure and kidney injury in male Dahl S rats. AHA 14SDG20160020

We have reported that a reduction in renal production of 20-HETE contributes to development of hypertension in Dahl salt-sensitive (SS) rats. The present study examined whether 20-HETE production is also reduced in the cerebral vasculature of SS rats and whether this impairs the myogenic response and autoregulation of cerebral blood flow (CBF). The production of 20-HETE, the myogenic response of middle cerebral arteries (MCA), and autoregulation of CBF were compared in SS, SS-5(BN) rats and a newly generated CYP4A1 transgenic rat. 20-HETE production was 6-fold higher in cerebral arteries of CYP4A1 and SS-5(BN) than in SS rats. The diameter of the MCA decreased to 70 ± 3% to 65 ± 6% in CYP4A1 and SS-5(BN) rats when pressure was increased from 40 to 140 mmHg. In contrast, the myogenic response of MCA isolated from SS rats did not constrict. Administration of a 20-HETE synthesis inhibitor, HET0016, abolished the myogenic response of MCA in CYP4A1 and SS-5(BN) rats but had no effect in SS rats. Autoregulation of CBF was impaired in SS rats compared with CYP4A1 and SS-5(BN) rats. Blood-brain barrier leakage was 5-fold higher in the brain of SS rats than in SS-5(BN) and SS.CYP4A1 rats. These findings indicate that a genetic deficiency in the formation of 20-HETE contributes to an impaired myogenic response in MCA and autoregulation of CBF in SS rats and this may contribute to vascular remodeling and cerebral injury following the onset of hypertension.

Cerebrovascular events contribute to ~40% of preeclampsia/eclampsia related deaths, and neurological symptoms are common among preeclamptic patients. We previously reported that placental ischemia, induced by reducing utero‐placental perfusion pressure, leads to impaired cerebrovascular myogenic reactivity and cerebral edema in the pregnant rat. Whether the impaired myogenic reactivity is associated with altered cerebral blood flow (CBF) autoregulation and the edema is due to altered blood‐brain barrier (BBB) permeability is unclear. Therefore, we tested the hypothesis that placental ischemia leads to impaired CBF autoregulation and a disruption of the BBB. CBF autoregulation, measured in vivo by laser Doppler flowmetry, was significantly impaired in placental ischemic rats compared to normal pregnant rats. Brain water content was increased in the anterior cerebrum of placental ischemic rats and BBB permeability, assayed using the Evans blue extravasation method, was also increased in the anterior cerebrum. The expression of the tight junction proteins: claudin‐1 was increased in the posterior cerebrum while zonula occludens‐1, and occludin, were not significantly altered in either the anterior or posterior cerebrum. These results are consistent with the hypothesis that placental ischemia mediates anterior cerebral edema through impaired CBF autoregulation and the associated increased transmission of pressure to microvessels, resulting in increased BBB permeability and cerebral edema.

The present study examined whether 20-HETE production is reduced in the renal vasculature and whether this impairs myogenic or tubuloglomerular feedback (TGF) responses of the afferent arteriole (Af-Art). The production of 20-HETE was 73% lower in renal microvessels of Dahl salt-sensitive rats (SS) rats than in SS.5(BN) rats, in which chromosome 5 from the Brown Norway (BN) rat containing the CYP4A genes was transferred into the SS genetic background. The luminal diameter of the Af-Art decreased by 14.7 ± 1.5% in SS.5(BN) rats when the perfusion pressure was increased from 60 to 120 mmHg, but it remained unaltered in SS rats. Administration of an adenosine type 1 receptor agonist (CCPA, 1 μM) reduced the diameter of the Af-Art in the SS.5(BN) rats by 44 ± 2%, whereas the diameter of the Af-Art of SS rats was unaltered. Autoregulation of renal blood flow (RBF) and glomerular capillary pressure (PGC) was significantly impaired in SS rats but was intact in SS.5(BN) rats. Administration of a 20-HETE synthesis inhibitor, HET0016 (1 μM), completely blocked the myogenic and adenosine responses in the Af-Art and autoregulation of RBF and PGC in SS.5(BN) rats, but it had no effect in SS rats. These data indicate that a deficiency in the formation of 20-HETE in renal microvessels impairs the reactivity of the Af-Art of SS rats and likely contributes to the development of hypertension induced renal injury.