Mutation of aspartic acid 262 on estrogen receptor abrogates estradiol signaling pathway

OBJECTIVE

ERα (estrogen receptor alpha) exerts nuclear genomic actions and membrane-initiated non-genomic effects. The mutation of aspartic acid into alanine in vitro revealed the critical role of aspartic acid 258 (corresponding to mouse amino acid site 262) of ERα for non-nuclear function. Our previous in vitro study revealed that this mutation blocked estrogen's non-genomic effects on vascular endothelial H2S release. Here, we studied the in vivo role of the aspartic acid 262 of ERα in the reproductive system and in the vascular tissue.

APPROACH AND RESULTS

We generated a mouse model harboring a point mutation of the murine counterpart of this aspartic acid into alanine (ERαD262A). Our results showed that the ERαD262A females are fertile with standard hormonal serum levels, but the uterine development and responded with estrogen and follicular development are disrupted. In line with our previous study, we found that the rapid dilation of the aorta was abrogated in ERαD262A mice. In contrast to the previously reported R264-ERα mice, the classical estrogen genomic effector SP1/NOS3/AP1 and the nongenomic effectors p-eNOs, p-AKT, and p-ERK were disturbed in the ERαD262A aorta. Besides, the serum H2S concentration was decreased in ERαD262A mice. Together, ERαD262A mice showed compromised both genomic and non-genomic actions in response to E2.

CONCLUSIONS

These data showed that aspartic acid 262 of ERα are important for both genomic and non-genomic effects of E2. Our data provide a theoretical basis for further selecting an effective non-genomic mouse model and provide a new direction for developing estrogen non-genomic effect inhibitors.

in human arteries

Fragaria vesca L. (wild strawberry) is traditionally used for its anti-inflammatory activity and for gastrointestinal, cardiovascular and urinary disorders. A previous study with the rat aorta showed that its leaves extract elicits endothelium-dependent vasorelaxation. Our aim was to investigate the clinical application of Fragaria vesca in vascular disease, by assessing the vascular effects of an infusion and hydroalcoholic extract in internal thoracic arteries from patients with coronary artery disease. The extracts elicited no effects on basal vascular tone and did not induce any vasorelaxation. At low concentration (0.02 mg/mL), the infusion potentiated the noradrenaline-induced contraction, while the other concentrations did not elicit significant changes in efficacy or potency. Differences between our findings and the previous report on rat aorta may result from methodological differences, e.g. vascular bed, method of extraction and extract composition. The clinical applicability of extracts of Fragaria vesca in patients with cardiovascular disease remains to be fully validated.

The Effects of chronic smoking on retinal vascular densities and choroidal thicknesses measured by optical coherence tomography angiography

PURPOSE

To examine the effects of chronic smoking on vascular density in superficial and deep retinal vascular plexuses and choroidal thicknesses.

METHOD

Superficial and deep vessel densities and choroidal thicknesses of smoking volunteers and healthy non-smoking volunteers were measured with the Topcon DRI OCT-1 Tritron® device and compared with each other.

RESULTS

This study included 108 eyes of 54 smoking volunteers and 108 eyes of 54 healthy volunteers as a control group. The average superficial vascular density index and deep vascular density indexes of smokers were found to be 39.81 ± 1.5% and 42.53 ± 1.9%, respectively (P = 0.53), while the non-smoking control group was 40.09 ± 1.3% and 41.57 ± 1.6%, respectively (P = 0.006). Average choroidal thicknesses were 284.22 ± 59 in smokers and 270.72 ± 61 in the control group (P = 0.247). Also, smoking quantity per day x years was found to be significantly negatively correlated with average choroidal thicknesses. (P = 0,011).

DISCUSSION

In this study, it was determined that chronic smoking increases deep retinal vascular densities on retinal vascular plexus. However, the cumulative effect of smoking was found to be negatively correlated with choroidal thicknesses. Smoking has microvascular effects on vessels such as vasodilatation, vasoconstriction, increased platelet aggregation, endothelial dysfunction. However, studies in the literature are in dispute with the effects of smoking on choroidal and retinal vessels. This study may show that chronic smoking may have different vascular effects on the superficial and deep plexuses and choroidal vessels, as well as different effects from acute use.

Nebivolol: an effective option against long-lasting dyspnoea following COVID-19 pneumonia - a pivotal double-blind, cross-over controlled study

Background

Pulmonary microvascular occlusions can aggravate SARS-CoV-2 pneumonia and result in a variable decrease in capillary blood volume (Vc). Dyspnoea may persist for several weeks after hospital discharge in many patients who have "radiologically recovered" from COVID-19 pneumonia. Dyspnoea is frequently "unexplained" in these cases because abnormalities in lung vasculature are understudied. Furthermore, even when they are identified, therapeutic options are still lacking in clinical practice, with nitric oxide (NO) supplementation being used only for severe respiratory failure in the hospital setting. Nebivolol is the only selective β¹ adrenoceptor antagonist capable of inducing nitric oxide-mediated vasodilation by stimulating endothelial NO synthase via β₃ agonism. The purpose of this study was to compare the effect of nebivolol versus placebo in patients who had low Vc and complained of dyspnoea for several weeks after COVID-19 pneumonia.

Methods

Patients of both genders, aged ≥18 years, non-smokers, who had a CT scan that revealed no COVID-related parenchymal lesions but still complaining of dyspnoea 12-16 weeks after hospital discharge, were recruited. Spirometrical volumes, blood haemoglobin, SpO₂, simultaneous diffusing capacity for carbon monoxide (CO) and NO (DL_CO and DL_NO, respectively), DL_NO/DL_CO ratio, Vc and exhaled NO (eNO) were measured together with their dyspnoea score (DS), heart frequency (HF), and blood arterial pressure (BAP). Data were collected before and one week after both placebo (P) and nebivolol (N) (2.5 mg od) double-blind cross-over administered at a two-week interval. Data were statistically compared, and p<0.05 assumed as statistically significant.

Results

Eight patients (3 males) were investigated. In baseline, their mean DS was 2.5±0.6 SD, despite the normality of lung volumes. DL_CO and DL_NO mean values were lower than predicted, while mean DL_NO/DL_CO ratio was higher. Mean Vc proved substantially reduced. Placebo did not modify any variable (all p=ns) while N improved DLco and Vc significantly (+8.5%, p<0.04 and +17.7%, p<0.003, respectively). eNO also was significantly increased (+17.6%, p<0.002). Only N lowered the dyspnoea score (-76%, p<0.001). Systolic and diastolic BAP were slightly lowered (-7.5%, p<0.02 and -5.1%, p<0.04, respectively), together with HF (-16.8%, p<0.03).

Conclusions

The simultaneous assessment of DL_NO, DL_CO, DL_NO/DL_CO ratio, and Vc confirmed that long-lasting dyspnoea is related to hidden abnormalities in the lung capillary vasculature. These abnormalities can persist even after the complete resolution of parenchymal lesions regardless of the normality of lung volumes. Nebivolol, but not placebo, improves DS and Vc significantly. The mechanism suggested is the NO-mediated vasodilation via the β3 adrenoceptor stimulation of endothelial NO synthase. This hypothesis is supported by the substantial increase of eNO only assessed after nebivolol. As the nebivolol tolerability in these post-COVID normotensive patients was very good, the therapeutic use of nebivolol against residual and symptomatic signs of long-COVID can be suggested in out-patients.

Arsenic exposure and non-carcinogenic health effects

Inorganic arsenic (iAs) exposure is a serious health problem that affects more than 140 million individuals worldwide, mainly, through contaminated drinking water. Acute iAs poisoning produces several symptoms such as nausea, vomiting, abdominal pain, and severe diarrhea, whereas prolonged iAs exposure increased the risk of several malignant disorders such as lung, urinary tract, and skin tumors. Another sensitive endpoint less described of chronic iAs exposure are the non-malignant health effects in hepatic, endocrine, renal, neurological, hematological, immune, and cardiovascular systems. The present review outlines epidemiology evidence and possible molecular mechanisms associated with iAs-toxicity in several non-carcinogenic disorders.

Bioavailable Blueberry-Derived Phenolic Acids at Physiological Concentrations Enhance Nrf2-Regulated Antioxidant Responses in Human Vascular Endothelial Cells

SCOPE

Blueberry consumption is believed to confer a cardiovascular health advantage, but the active compounds and effects require characterization. This study aims to identify the polyphenol metabolites in plasma after blueberry juice intake and determine their bioactivity on endothelial cells.

METHODS AND RESULTS

Three healthy individuals are recruited to obtain profiles of bioavailable plasma polyphenol metabolites following intake of blueberry juice. Of 33 phenolic compounds screened, 12 aglycone phenolic acids are detected and their maximum plasma concentrations and circulation time determined. Using this information, the effect of three physiologically relevant mixtures of blueberry-derived phenolic acids is investigated for their ability to induce nuclear factor erythroid 2-related factor 2 (Nrf2)-nuclear translocation and downstream gene expression in human endothelial cells. Pretreatment with the phenolic acids for 18 h results in a significant upregulation of the Nrf2-regulated antioxidant response proteins heme oxygenase 1 (HO-1) and glutamate-cysteine ligase modifier subunit (GCLM), following 6 h exposure to 2.5 μm H₂ O₂ .

CONCLUSION

Physiologically relevant concentrations of blueberry-derived aglycone phenolic acids can induce Nrf2-regulated antioxidant response proteins in vascular endothelial cells in response to low μm concentrations of H₂ O₂ . Our results represent an advance over previous studies that have used single compounds or high concentrations in cell-based investigations.

Blueberry Metabolites Attenuate Lipotoxicity-Induced Endothelial Dysfunction

SCOPE

Lipotoxicity-induced endothelial dysfunction is an important vascular complication associated with diabetes. Clinical studies support the vascular benefits of blueberry anthocyanins, but the underlying mechanism is unclear. The hypothesis that metabolites of blueberry anthocyanins attenuate lipotoxicity-induced endothelial dysfunction was tested.

METHODS AND RESULTS

Human aortic endothelial cells (HAECs) were treated for 6 h with either: (i) the parent anthocyanins (malvidin-3-glucoside and cyanidin-3-glucoside); or (ii) the blueberry metabolites (hydroxyhippuric acid, hippuric acid, benzoic acid-4-sulfate, isovanillic acid-3-sulfate, and vanillic acid-4-sulfate), at concentrations known to circulate in humans following blueberry consumption. For the last 5 h HAECs were treated with palmitate or vehicle. HAECs treated with palmitate displayed elevated reactive oxygen species generation, increased mRNA expression of NOX4, chemokines, adhesion molecules, and IκBα, exaggerated monocyte binding, and suppressed nitric oxide production. Of note, the damaging effects of palmitate were ameliorated in HAECs treated with blueberry metabolites but not parent anthocyanins. Further, important translational relevance of these results was provided by our observation that palmitate-induced endothelial dysfunction was lessened in arterial segments that incubated concurrently with blueberry metabolites.

CONCLUSION

The presented findings indicate that the vascular benefits of blueberry anthocyanins are mediated by their metabolites. Blueberries might complement existing therapies to lessen vascular complications.

Mutation of the palmitoylation site of estrogen receptor α in vivo reveals tissue-specific roles for membrane versus nuclear actions

Estrogen receptor alpha (ERα) activation functions AF-1 and AF-2 classically mediate gene transcription in response to estradiol (E2). A fraction of ERα is targeted to plasma membrane and elicits membrane-initiated steroid signaling (MISS), but the physiological roles of MISS in vivo are poorly understood. We therefore generated a mouse with a point mutation of the palmitoylation site of ERα (C451A-ERα) to obtain membrane-specific loss of function of ERα. The abrogation of membrane localization of ERα in vivo was confirmed in primary hepatocytes, and it resulted in female infertility with abnormal ovaries lacking corpora lutea and increase in luteinizing hormone levels. In contrast, E2 action in the uterus was preserved in C451A-ERα mice and endometrial epithelial proliferation was similar to wild type. However, E2 vascular actions such as rapid dilatation, acceleration of endothelial repair, and endothelial NO synthase phosphorylation were abrogated in C451A-ERα mice. A complementary mutant mouse lacking the transactivation function AF-2 of ERα (ERα-AF2(0)) provided selective loss of function of nuclear ERα actions. In ERα-AF2(0), the acceleration of endothelial repair in response to estrogen-dendrimer conjugate, which is a membrane-selective ER ligand, was unaltered, demonstrating integrity of MISS actions. In genome-wide analysis of uterine gene expression, the vast majority of E2-dependent gene regulation was abrogated in ERα-AF2(0), whereas in C451A-ERα it was nearly fully preserved, indicating that membrane-to-nuclear receptor cross-talk in vivo is modest in the uterus. Thus, this work genetically segregated membrane versus nuclear actions of a steroid hormone receptor and demonstrated their in vivo tissue-specific roles.

Vascular kinin B(1) and B(2) receptor-mediated effects in the rat isolated perfused kidney - differential regulations

1. Bradydykinin (BK) and analogs acting preferentially at kinin B(1) or B(2) receptors were tested on the rat isolated perfused kidney. Kidneys were perfused in an open circuit with Tyrode's solution. Kidneys preconstricted with prostaglandin F(2alpha) were used for the analysis of vasodilator responses. 2. BK induced a concentration-dependent renal relaxation (pD(2)=8.9+/-0.4); this vasodilator response was reproduced by a selective B(2) receptor agonist, Tyr(Me)(8)-BK (pD(2)=9.0+/-0.1) with a higher maximum effect (E(max)=78.9+/-6.6 and 55.8+/-4.3% of ACh-induced relaxation respectively, n=6 and 19, P<0.02). Icatibant (10 nM), a selective B(2) receptor antagonist, abolished BK-elicited relaxation. Tachyphylaxis of kinin B(2) receptors appeared when repeatedly stimulated at 10 min intervals. 3. Des-Arg(9)-BK, a selective B(1) receptor agonist, induced concentration-dependent vasoconstriction at micromolar concentration. Maximum response was enhanced in the presence of lisinopril (1 microM) and inhibited by R 715 (8 microM), a selective B(1) receptor antagonist. Des-Arg(9)-[Leu(8)]-BK behaved as an agonist. 4. A contractile response to des-Arg(9)-BK occurred after 1 of perfusion and increased with time by a factor of about three over a 3 h perfusion. This post-isolation sensitization to des-Arg(9)-BK was abolished by dexamethasone (DEX, 30 mg kg(-1) i.p., 3 h before the start of the experiment and 10 microM in perfusate) and actinomycin D (2 microM). Acute exposure to DEX (10 microM) had no effect on sensitized des-Arg(9)-BK response, in contrast to indomethacin (30 microM) that abolished it. DEX pretreatment however had no effect on BK-induced renal vasodilation. 5. Present results indicate that the main renal vascular response to BK consists of relaxation linked to the activation of kinin B(2) receptors which rapidly desensitize. Renal B(1) receptors are also present and are time-dependently sensitized during the in vitro perfusion of the rat kidneys.