Hypercholesterolemia decreases nitric oxide production by promoting the interaction of caveolin and endothelial nitric oxide synthase

Assessment of Registered Clinical Trial Designs: Comparison of L-Arginine and/or L-Citrulline Interventions for Hypertension

BACKGROUND

L-Arginine (Arg) is an essential amino acid and a precursor for the synthesis of vascular nitric oxide, while L-Citrulline is a non-essential amino acid substrate for increasing L-arginine. Both L-arginine and L-Citrulline in translational studies may acutely lower the blood pressure. Current meta-analysis for L-arginine or L-Citrulline interventions in blood pressure have identified significant heterogeneity. Clinical trial evidence for L-arginine or L-Citrulline in chronic blood pressure reduction in the general population requires an examination of trial designs, as not all translational studies may have influenced vascular reactivity. Our aims are to explore whether L-arginine and L-citrulline intervention trials in chronic blood pressure consider standardized end points relevant to the general adult populations.

METHODS

A step-wise search on clinicaltrials.gov, the U.S. Library of Medicine registry for clinical trials, was performed including the following keyword search parameters: "completed" "L-Citrulline" "L-arginine" trial", and "adults", involving "blood pressure" reduction as a primary end point in adult humans.

RESULTS

Of the forty-four completed trials, only five were included for analysis. Following the careful evaluation of trial design, we observed heterogeneity across participant inclusion criteria (population sample size, age range, sex), interventional design (dosages, duration), and primary outcomes, measured with respect to changes in diastolic or systolic blood pressure.

CONCLUSION

In conclusion, there is a lack of robust trial design evidence to suggest that L-arginine or L-Citrulline, based on current RCTs in the general population, have an overall positive effect on vascular endothelial reactivity and a beneficial chronic blood pressure-lowering effect. Indeed, conclusions drawn from human meta-analysis studies have been heterogenous between studies, which may be attributed to study design heterogeneity, including differences in sample population, age, and blood pressure at the time of entry. Inconsistencies in the study design poses a challenge for systematic reviews and meta-analysis to accurately assess the effect size and impact of L-arginine or L-citrulline on both systolic and diastolic blood pressure.

Excessive hypercholesterolemia in pregnancy impairs rat uterine artery function via activation of Toll-like receptor 4

Hypercholesterolemia in pregnancy is a physiological process required for normal fetal development. In contrast, excessive pregnancy-specific hypercholesterolemia increases the risk of complications, such as preeclampsia. However, the underlying mechanisms are unclear. Toll-like receptor 4 (TLR4) is a membrane receptor modulated by high cholesterol levels, leading to endothelial dysfunction; but whether excessive hypercholesterolemia in pregnancy activates TLR4 is not known. We hypothesized that a high cholesterol diet (HCD) during pregnancy increases TLR4 activity in uterine arteries, leading to uterine artery dysfunction. Sprague Dawley rats were fed a control diet (n=12) or HCD (n=12) during pregnancy (gestational day 6-20). Vascular function was assessed in main uterine arteries using wire myography (vasodilation to methacholine and vasoconstriction to phenylephrine; with and without inhibitors for mechanistic pathways) and pressure myography (biomechanical properties). Exposure to a HCD during pregnancy increased maternal blood pressure, induced proteinuria, and reduced the fetal-to-placental weight ratio for both sexes. Excessive hypercholesterolemia in pregnancy also impaired vasodilation to methacholine in uterine arteries, whereby at higher doses, methacholine caused vasoconstriction instead of vasodilation in only the HCD group, which was prevented by inhibition of TLR4 or prostaglandin H synthase 1. Endothelial nitric oxide synthase expression and nitric oxide levels were reduced in HCD compared with control dams. Vasoconstriction to phenylephrine and biomechanical properties were similar between groups. In summary, excessive hypercholesterolemia in pregnancy impairs uterine artery function, with TLR4 activation as a key mechanism. Thus, TLR4 may be a target for therapy development to prevent adverse perinatal outcomes in complicated pregnancies.

Mechanosensing by Vascular Endothelium

Mechanical forces influence different cell types in our bodies. Among the earliest forces experienced in mammals is blood movement in the vascular system. Blood flow starts at the embryonic stage and ceases when the heart stops. Blood flow exposes endothelial cells (ECs) that line all blood vessels to hemodynamic forces. ECs detect these mechanical forces (mechanosensing) through mechanosensors, thus triggering physiological responses such as changes in vascular diameter. In this review, we focus on endothelial mechanosensing and on how different ion channels, receptors, and membrane structures detect forces and mediate intricate mechanotransduction responses. We further highlight that these responses often reflect collaborative efforts involving several mechanosensors and mechanotransducers. We close with a consideration of current knowledge regarding the dysregulation of endothelial mechanosensing during disease. Because hemodynamic disruptions are hallmarks of cardiovascular disease, studying endothelial mechanosensing holds great promise for advancing our understanding of vascular physiology and pathophysiology.

Influence of Atherosclerotic Risk Factors on the Effectiveness of Therapeutic Ultrasound Cavitation for Flow Augmentation

BACKGROUND

Shear created by inertial cavitation of microbubbles by ultrasound augments limb and myocardial perfusion and can reverse tissue ischemia. Our aim was to determine whether this therapeutic bioeffect is attenuated by atherosclerotic risk factors that are known to impair shear-mediated vasodilation and adversely affect microvascular reactivity.

METHODS

In mice, lipid-stabilized decafluorobutane microbubbles (2 × 108) were administered intravenously while exposing a proximal hind limb to ultrasound (1.3 MHz, 1.3 mechanical index, pulsing interval 5 seconds) for 10 minutes. Murine strains included wild-type mice and severely hyperlipidemic mice at 15, 35, or 52 weeks of age as a model of aging and elevated cholesterol, and obese db/db mice (≈15 weeks) with severe insulin resistance. Quantitative contrast-enhanced ultrasound perfusion imaging was performed to assess microvascular perfusion in the control and ultrasound-exposed limb. An in situ electrochemical probe and in vivo biophotonic imaging were used to assess limb nitric oxide (NO) and adenosine triphosphosphate concentrations, respectively.

RESULTS

Microvascular perfusion was significantly increased by several fold in the cavitation-exposed limb versus control limb for all murine strains and ages (P < .001). In wild-type and hyperlipidemic mice, hyperemia from cavitation was attenuated in the 2 older age groups (P < .01). In young mice (15 weeks), perfusion in cavitation-exposed muscle was less in both the hyperlipidemic mice and the obese db/db mice compared with corresponding wild-type mice. Using young hyperlipidemic mice as a model for flow impairment, limb NO production after cavitation was reduced but adenosine triphosphosphate production was unaltered when compared with age-matched wild-type mice.

CONCLUSIONS

In mice, ultrasound cavitation of microbubbles increases limb perfusion by several fold even in the presence of traditional atherosclerotic risk factors. However, older age, hyperlipidemia, and insulin resistance modestly attenuate the degree of flow augmentation, which could impact the degree of flow response in current clinical trials in patients with critical limb ischemia.

The Biological Parallels Between Atherosclerosis and Cardiac Allograft Vasculopathy: Implications for Solid Organ Chronic Rejection

Atherosclerosis and solid organ chronic rejection are pervasive chronic disease states that account for significant morbidity and mortality in developed countries. Recently, a series of shared molecular pathways have emerged, revealing biological parallels from early stages of development up to the advanced forms of pathology. These shared mechanistic processes are inflammatory in nature, reflecting the importance of inflammation in both disorders. Vascular inflammation triggers endothelial dysfunction and disease initiation through aberrant vasomotor control and shared patterns of endothelial activation. Endothelial dysfunction leads to the recruitment of immune cells and the perpetuation of the inflammatory response. This drives lesion formation through the release of key cytokines such as IFN-y, TNF-alpha, and IL-2. Continued interplay between the adaptive and innate immune response (represented by T lymphocytes and macrophages, respectively) promotes lesion instability and thrombotic complications; hallmarks of advanced disease in both atherosclerosis and solid organ chronic rejection. The aim of this study is to identify areas of overlap between atherosclerosis and chronic rejection. We then discuss new approaches to improve current understanding of the pathophysiology of both disorders, and eventually design novel therapeutics.

Development of a novel Guinea Pig model producing transgenerational endothelial transcriptional changes driven by maternal food restriction and a second metabolic insult of high fat diet

Developmental programming of chronic adverse cardiovascular health outcomes has been studied both using numerous human populations and an array of animal models. However, the mechanisms that produce transgenerational effects have been difficult to study due to a lack of developmentally relevant models. As such, how increased disease risk is carried to the second generation has been poorly studied. We hypothesized that the endothelium which mediates many acute and chronic vascular inflammatory responses is a key player in these effects, and epidemiological studies implicate transgenerational nutritional effects on endothelial health. To study the mutigenerational effects of maternal undernutrition on offspring endothelial health, we developed a model of transgenerational nutritional stress in guinea pigs, a translationally relevant precocial species with a relatively short lifespan. First- and second-generation offspring were subjected to a high fat diet in adolescence to exacerbate negative cardiovascular health. To assess transcriptional changes, we performed bulk RNA-sequencing in carotid artery endothelial cells, with groups stratified as prenatal control or food restricted, and postnatal control or high fat diet. We detected statistically significant gene alterations for each dietary permutation, some of which were unique to treatments and other transcriptional signatures shared by multiple or all conditions. These findings highlight a core group of genes altered by high fat diet that is shared by all cohorts and a divergence of transgenerational effects between the prenatal ad libitum and dietary restriction groups. This study establishes the groundwork for this model to be used to better understand the interplay of prenatal stress and genetic reprogramming.

Membrane Cholesterol Interactions with Proteins in Hypercholesterolemia-Induced Endothelial Dysfunction

PURPOSE OF REVIEW

The goal of this review is to highlight work identifying mechanisms driving hypercholesterolemia-mediated endothelial dysfunction. We specifically focus on cholesterol-protein interactions and address specific questions related to the impact of hypercholesterolemia on cellular cholesterol and vascular endothelial function. We describe key approaches used to determine the effects of cholesterol-protein interactions in mediating endothelial dysfunction under dyslipidemic conditions.

RECENT FINDINGS

The benefits of removing the cholesterol surplus on endothelial function in models of hypercholesterolemia is clear. However, specific mechanisms driving cholesterol-induced endothelial dysfunction need to be determined. In this review, we detail the latest findings describing cholesterol-mediated endothelial dysfunction, highlighting our studies indicating that cholesterol suppresses endothelial Kir2.1 channels as a major underlying mechanism. The findings detailed in this review support the targeting of cholesterol-induced suppression of proteins in restoring endothelial function in dyslipidemic conditions. The identification of similar mechanisms regarding other cholesterol-endothelial protein interactions is warranted.

The effect of microencapsulated watermelon rind (Citrullus lanatus) and beetroot (Beta vulgaris L.) ingestion on ischemia/reperfusion-induced endothelial dysfunction: a randomised clinical trial

Endothelial dysfunction is commonly associated with a cardiovascular event, such as myocardial infarction. Myocardial infarction is marked by an ischemia/reperfusion (IR) phenomenon associated with endothelial dysfunction, contributing even more to future cardiovascular events. Although the supplementation with L-citrulline and nitrate from watermelon and beetroot have been used to improve vascular function, the effect of microencapsulated watermelon rind (WR) or its co-ingestion with beetroot (WR + B) on endothelial IR injury has not been addressed. Therefore, this study aimed to investigate the effect of a single dose of WR and WR + B on IR-induced macro-and microvascular dysfunction. In a randomized, crossover, placebo-controlled study, 12 volunteers underwent macro (flow-mediated dilation) and microvascular (muscle oxygen saturation) assessment and blood collection (to measure L-citrulline, L-arginine, nitrate and nitrite) before and after 20 min of blood occlusion in WR, WR + B and placebo conditions. Prolonged ischemia induced endothelial dysfunction in the macro but not in the microvasculature. The WR and WR + B supplementation significantly restored FMD after IR injury compared to the placebo (p < 0.05). However, there was no significant difference between WR and WR + B in the macrovascular function (p > 0.05). Plasma L-citrulline, L-arginine, nitrate, and nitrite significantly increased (p > 0.05) after WR and WR + B supplementation compared to the placebo. A single dose of WR and WR + B effectively minimizes IR-induced macrovascular endothelial dysfunction in healthy individuals. Beetroot co-ingestion with watermelon did not provide an additional effect of endothelial dysfunction induced by IR (NCT04781595, March 4, 2021).

Effect of Low Protein Diet Supplemented with Ketoanalogs on Endothelial Function and Protein-Bound Uremic Toxins in Patients with Chronic Kidney Disease

Studies have demonstrated that a low-protein diet supplemented with ketoanalogs (KAs) could significantly retard progression of renal function in patients with chronic kidney disease (CKD) stages 3-5. However, its effects on endothelial function and serum levels of protein-bound uremic toxins remain elusive. Therefore, this study explored whether a low-protein diet (LPD) supplemented with KAs affects kidney function, endothelial function, and serum uremic toxin levels in a CKD-based cohort. In this retrospective cohort, we enrolled 22 stable CKD stage 3b-4 patients on LPD (0.6-0.8 g/day). Patients were categorized into control (LPD only) and study groups (LPD + KAs 6 tab/day). Serum biochemistry, total/free indoxyl sulfate (TIS/FIS), total/free p-cresyl sulfate (TPCS/FPCS), and flow-mediated dilation (FMD) were measured before and after 6 months of KA supplementation. Before the trial, there were no significant differences in kidney function, FMD, or uremic toxin levels between the control and study groups. When compared with the control group, the paired t-test showed a significant decrease in TIS and FIS (all p < 0.05) and a significant increase in FMD, eGFR, and bicarbonate (all p < 0.05). In multivariate regression analysis, an increase in FMD (p < 0.001) and a decrease in FPCS (p = 0.012) and TIS (p < 0.001) remained persistent findings when adjusted for age, systolic blood pressure (SBP), sodium, albumin, and diastolic blood pressure (DBP). LPD supplemented with KAs significantly preserves kidney function and provides additional benefits on endothelial function and protein-bound uremic toxins in patients with CKD.

Regulation of ThermoTRP Channels by PIP2 and Cholesterol

Transient receptor potential (TRP) ion channels are proteins that are expressed by diverse tissues and that play pivotal functions in physiology. These channels are polymodal and are activated by several stimuli. Among TRPs, some members of this family of channels respond to changes in ambient temperature and are known as thermoTRPs. These proteins respond to heat or cold in the noxious range and some of them to temperatures considered innocuous, as well as to mechanical, osmotic, and/or chemical stimuli. In addition to this already complex ability to respond to different signals, the activity of these ion channels can be fine-tuned by lipids. Two lipids well known to modulate ion channel activity are phosphatidylinositol 4,5-bisphosphate (PIP2) and cholesterol. These lipids can either influence the function of these proteins through direct interaction by binding to a site in the structure of the ion channel or through indirect mechanisms, which can include modifying membrane properties, such as curvature and rigidity, by regulating their expression or by modulating the actions of other molecules or signaling pathways that affect the physiology of ion channels. Here, we summarize the key aspects of the regulation of thermoTRP channels by PIP2 and cholesterol.

Effects of Antirheumatic Treatment on Cell Cholesterol Efflux and Loading Capacity of Serum Lipoproteins in Spondylarthropathies

Spondyloarthropathies (SpA) are associated with increased cardiovascular risk. Among possible mechanisms is the dysfunction of serum lipoproteins in regulating cell cholesterol homeostasis. Cholesterol efflux capacity (CEC)-the atheroprotective ability of HDL (high density lipoproteins) to accept cholesterol from macrophages-might predict cardiovascular disease independently of HDL-cholesterol levels. We aimed at evaluating modifications of CEC and of the atherogenic cholesterol loading capacity (CLC) of serum lipoproteins in psoriatic arthritis (PsA) and ankylosing spondylitis (AS) following anti-rheumatic treatment. A total of 62 SpA patients (37 PsA and 25 AS) were evaluated before and after treatment with tumor necrosis factor inhibitor and/or methotrexate. CEC and CLC were measured by radioisotopic and fluorometric techniques, respectively. Endothelial function was assessed by finger plethysmography (Endopat). In the whole SpA group, total and HDL-cholesterol increased after treatment, while lipoprotein(a) decreased and CLC was unchanged. Treatment was associated with increased Scavenger Receptor class B type I (SR-BI)-mediated CEC in the AS group. SR-BI- and ABCG1-mediated CEC were negatively associated with inflammatory parameters and positively related to coffee consumption. SR-BI CEC and CLC were positively and negatively associated with endothelial function, respectively. Our pilot study suggests that anti-rheumatic treatment is associated with favorable modulation of lipoprotein quality and function in SpA, particularly in AS, in spite of the induced increase in total cholesterol levels. If confirmed in a larger population, this might represent an atheroprotective benefit beyond what is reflected by conventional serum lipid profile.

Viperin impairs the innate immune response through the IRAK1-TRAF6-TAK1 axis to promote Mtb infection

Mycobacterium tuberculosis (Mtb) infection is a long-standing public health threat, and the development of host-directed therapy for eradicating Mtb infection requires better insights into Mtb-host interactions. Viperin [virus-inhibitory protein, endoplasmic reticulum-associated, interferon (IFN) inducible] is an IFN-inducible protein with broad antiviral activities. Here, we demonstrated that Viperin was increased in abundance in patients with lymphatic and pulmonary tuberculosis (TB). Viperin-deficient mice had decreased Mtb bacterial loads and enhanced macrophage responses compared with their wild-type counterparts. Viperin suppressed the formation of a complex containing interleukin-1 receptor-associated kinase 1, TNF receptor-associated factor 6, and transforming growth factor β-activated kinase 1 (TAK1) and inhibited the TAK1-dependent activation of IκB kinase α/β, thereby impairing the production of nitric oxide and proinflammatory cytokines. These results suggest that Viperin promotes Mtb infection by inhibiting host innate immune responses in macrophages, suggesting that Viperin may be a candidate target for adjunct host-directed therapy in patients with TB.

Orlistat Mitigates Oxidative Stress-Linked Myocardial Damage via NF-κβ- and Caspase-Dependent Activities in Obese Rats

Oxidative stress contributes to major complications of obesity. This study intended to identify whether orlistat could mitigate myocardial damage in obese animal models. The tested rats were divided into two groups and fed either with normal chow (n = 6 per group) or with a high-fat diet (HFD) for 6 weeks to induce obesity (n = 12 per group). Obese rats were further subjected to treatment either with distilled water (OB group) or orlistat 10 mg/kg/day (OB + OR group). Key indices of oxidative stress, inflammation, and apoptosis were assessed using an immunohistochemical-based technique and real-time PCR. The OB group showed significant increases of oxidative stress markers (TBARs and PCO), with significant decreases of anti-oxidant markers (Nrf2, SOD, CAT, and GPx). Furthermore, mRNA expression of pro-inflammatory markers (TNF-α and NF-κβ) and pro-apoptosis markers (Bax, Caspase-3, Caspase-8, and Caspase-9) were significantly upregulated in the OB group. Obese rats developed pathological changes of myocardial damages as evidenced by the presence of myocardial hypertrophy and inflammatory cells infiltration. Orlistat dampened the progression of myocardial damage in obese rats by ameliorating the oxidative stress, and by inhibiting NF-κβ pathway and caspase-dependent cell apoptosis. Our study proposed that orlistat could potentially mitigate oxidative stress-linked myocardial damage by mitigating inflammation and apoptosis, thus rationalizing its medical usage.

The effect of dietary nitrate on macro- and microvascular function: A systematic review

Previous studies have investigated the impact of dietary nitrate on vascular function due to the association between dietary nitrate ingestion and improvement in nitric oxide (NO) bioavailability. Considering that NO can present different effects through vascular beds (macro- vs. microvasculature) due to the specific characteristic (function and morphology) that each vessel exhibits, it is crucial to investigate the effect of dietary nitrate ingestion on the macro- and microvascular function to understand the effect of nitrate on vascular function. For this reason, this review aimed to evaluate the impact of dietary nitrate on macro- and microvascular function in humans. A total of 29 studies were included in the systematic review, of which 19 studies evaluated the effect of nitrate supplementation on macrovascular function, eight studies evaluated the effect on microvascular function, and two studies evaluated the impact on both macro- and microvascular function. The literature suggests that dietary nitrate ingestion seems to improve the vascular function in macrovasculature, whereas microvascular function appears to be modest. Future studies investigating the effect of nitrate ingestion on vascular function should focus on measuring macro- and microvascular function whenever possible so that the impact of nitrate-rich foods on vascular segments could be better understood.

Current Evidence of Watermelon (Citrullus lanatus) Ingestion on Vascular Health: A Food Science and Technology Perspective

The amino acid L-arginine is crucial for nitric oxide (NO) synthesis, an important molecule regulating vascular tone. Considering that vascular dysfunction precedes cardiovascular disease, supplementation with precursors of NO synthesis (e.g., L-arginine) is warranted. However, supplementation of L-citrulline is recommended instead of L-arginine since most L-arginine is catabolized during its course to the endothelium. Given that L-citrulline, found mainly in watermelon, can be converted to L-arginine, watermelon supplementation seems to be effective in increasing plasma L-arginine and improving vascular function. Nonetheless, there are divergent findings when investigating the effect of watermelon supplementation on vascular function, which may be explained by the L-citrulline dose in watermelon products. In some instances, offering a sufficient amount of L-citrulline can be impaired by the greater volume (>700 mL) of watermelon needed to reach a proper dose of L-citrulline. Thus, food technology can be applied to reduce the watermelon volume and make supplementation more convenient. Therefore, this narrative review aims to discuss the current evidence showing the effects of watermelon ingestion on vascular health parameters, exploring the critical relevance of food technology for acceptable L-citrulline content in these products. Watermelon-derived L-citrulline appears as a supplementation that can improve vascular function, including arterial stiffness and blood pressure. Applying food technologies to concentrate bioactive compounds in a reduced volume is warranted so that its ingestion can be more convenient, improving the adherence of those who want to ingest watermelon products daily.

Lipid rafts as viral entry routes and immune platforms: A double-edged sword in SARS-CoV-2 infection?

Lipid rafts are nanoscopic compartments of cell membranes that serve a variety of biological functions. They play a crucial role in viral infections, as enveloped viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can exploit rafts to enter or quit target cells. On the other hand, lipid rafts contribute to the formation of immune synapses and their proper functioning is a prerequisite for adequate immune response and viral clearance. In this narrative review we dissect the panorama focusing on this singular aspect of cell biology in the context of SARS-CoV-2 infection and therapy. A lipid raft-mediated mechanism can be hypothesized for many drugs recommended or considered for the treatment of SARS-CoV-2 infection, such as glucocorticoids, antimalarials, immunosuppressants and antiviral agents. Furthermore, the additional use of lipid-lowering agents, like statins, may affect the lipid composition of membrane rafts and thus influence the processes occurring in these compartments. The combination of drugs acting on lipid rafts may be successful in the treatment of more severe forms of the disease and should be reserved for further investigation.

Evaluation of Oxidative Stress Biomarkers, Pro-Inflammatory Cytokines, and Histological Changes in Experimental Hypertension, Dyslipidemia, and Type 1 Diabetes Mellitus

The present study aims to compare the oxidative stress biomarkers, pro-inflammatory cytokines, and histological changes induced by three cardiovascular risk factors, namely, hypertension, dyslipidemia, and type 1 diabetes mellitus. Hypertension was induced with 40 mg/kg body weight (b.w.) of N omega-nitro-L-arginine-methyl (L-NAME) administered orally. Dyslipidemia was induced by the administration of a diet with a high cholesterol (2%) content. Diabetes mellitus was induced by intraperitoneal administration of a single dose of streptozocin (65 mg/kg). Malondialdehyde (MDA) and total oxidative status (TOS) are increased by all three cardiovascular risk factors (up to 207%). The indirect assessment of NO synthesis (NOx) is observed to be reduced after L-NAME administration (43%), and dyslipidemia induction (16%), while type 1 diabetes mellitus is associated with the highest levels of NOx (increased 112%). Hypertension, dyslipidemia, and type 1 diabetes reduced the total antioxidative capacity (TAC) and total thiol (SH) levels (up to 57%). The values of evaluated pro-inflammatory cytokines, tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β), assessed from the ascending aorta were elevated by all three cardiovascular risk factors, with the highest levels induced by type 1 diabetes mellitus (up to 259%). The histopathological examination of the ascending and descending aorta revealed reversible pro-atherogenic changes consisting of the accumulation of lipid droplets in the subendothelial connective tissue on rats with hypertension and dyslipidemia. Irreversible pro-atherogenic changes consisting of a reduction of the specific elasticity of the arteries were observed in rats with type 1 diabetes mellitus. Type 1 diabetes mellitus demonstrates an alteration of the oxidative stress parameters, the elevation of tissue levels of the pro-inflammatory cytokines and causing irreversible pro-atherogenic changes on the aortic wall.

Nitric Oxide Synthase activity in major depressive episodes before and after antidepressant treatment: Results of a large case-control treatment study

BACKGROUND

Nitric oxide synthase (NOS) activity, an enzyme potentially involved in the major depressive episodes (MDE), could be indirectly measured by the L-Citrulline/L-Arginine ratio (L-Cit/L-Arg). The aim of this study was: (1) to compare the NOS activity of patients with a MDE to that of healthy controls (HC); (2) to assess its change after antidepressant treatment.

METHODS

A total of 460 patients with a current MDE in a context of major depressive disorder (MDD) were compared to 895 HC for NOS activity (L-Cit/L-Arg plasma ratio). L-Arg and L-Cit plasma levels were measured using a MS-based liquid chromatography method. Depressed patients were assessed at baseline, and after 3 and 6 months of antidepressant treatment for depression severity and clinical response.

RESULTS

Depressed patients had a lower NOS activity than HC at baseline [0.31 ± 0.09 v. 0.38 ± 0.12; 95% confidence interval (CI) -0.084 to -0.062, p < 0.0001]. Lower NOS activity at baseline predicted a higher response rate [odds ratio (OR) = 29.20; 95% CI 1.58-536.37; p = 0.023]. NOS activity in depressed patients increased significantly up to 0.34 ± 0.08 after antidepressant treatment (Est = 0.0034; 95% CI 0.0002-0.0067; p = 0.03).

CONCLUSIONS

Depressed patients have a decreased NOS activity that improves after antidepressant treatment and predicts drug response. NOS activity may be a promising biomarker for MDE in a context of MDD.

Endothelial Nitric Oxide Synthase (eNOS) and the Cardiovascular System: in Physiology and in Disease States

Endothelial nitric oxide synthase (eNOS) plays a critical role in regulating and maintaining a healthy cardiovascular system. The importance of eNOS can be emphasized from the genetic polymorphisms of the eNOS gene, uncoupling of eNOS dimerization, and its numerous signaling regulations. The activity of eNOS on the cardiac myocytes, vasculature, and the central nervous system are discussed. The effects of eNOS on the sympathetic autonomic nervous system (SANS) and the parasympathetic autonomic nervous system (PANS), both of which profoundly influence the cardiovascular system, will be elaborated. The relationship between the eNOS protein with cardiovascular autonomic reflexes such as the baroreflex and the Exercise Pressor Reflex will be discussed. For example, the effects of endogenous nitric oxide (NO) are shown to be mediated by the eNOS protein and that eNOS-derived endothelial NO is most effective in regulating blood pressure oscillations via modulating the baroreflex mechanisms. The protective action of eNOS on the CVS is emphasized here because dysfunction of the eNOS enzyme is intricately correlated with the pathogenesis of several cardiovascular diseases such as hypertension, arteriosclerosis, myocardial infarction, and stroke. Overall, our current understanding of the eNOS protein with a focus on its role in the modulation, regulation, and control of the cardiovascular system in a normal physiological state and in cardiovascular diseases are discussed.

Evaluation of Oxidative Stress Status in Familial Hypercholesterolemia

Background: Familial hypercholesterolemia (FH) is an autosomal dominant genetic disorder characterizied by elevated levels of circulating low-density lipoprotein cholesterol (LDL-C) which is an important source of substrates to be oxidized by different oxidative agents. Subsequently, the oxidized LDLs (oxLDLs) induce further oxidative reactions in FH patients, which contributes to the development of atherosclerosis and advanced cardiovascular events in these patients. This study aimed to investigate the association of oxidant/antioxidant markers with FH. Methods: This case-control study comprised 18 HoFH, 18 HeFH, and 20 healthy subjects. Oxidant/antioxidant markers including MDA, MPO, thiol, nitric oxide (NO), myeloperoxidase (MPO), glutathione peroxidase (GPx), SOD, and CAT were assessed by colorimetric methods. Prooxidant-antioxidant balance was also measured by pro-oxidant antioxidant balance (PAB) assay. Results: The levels of MDA (p < 0.001), MPO activity (p < 0.001), thiol (p < 0.001), NO (p < 0.01), and PAB (p < 0.001) were notably higher in HoFH group in comparison with healthy subjects. HeFH group also showed significantly higher levels of thiol (p < 0.001) and PAB (p < 0.001) when compared to healthy subjects. Elevated levels of MDA (p < 0.001) and PAB (p < 0.001) were also observed in HoFH relative to HeFH. No significant differences were found between the studied groups in the case of antioxidant enzyme activities. The results of binary logistic regression showed that PAB (OR: 0.979; p = 0.033), and MDA (OR: 0.996; p = 0.018) levels were inversely associated with HoFH, although, after adjustment for age and LDL-C levels, these associations were diminished. Conclusion: Several oxidant/antioxidant differences were found between FH patients and healthy individuals as well as between HoFH and HeFH patients. These differences might be strongly dependent on plasma LDL-C levels.

The Link between Gut Dysbiosis Caused by a High-Fat Diet and Hearing Loss

This review aims to provide a conceptual and theoretical overview of the association between gut dysbiosis and hearing loss. Hearing loss is a global health issue; the World Health Organisation (WHO) estimates that 2.5 billion people will be living with some degree of hearing loss by 2050. The aetiology of sensorineural hearing loss (SNHL) is complex and multifactorial, arising from congenital and acquired causes. Recent evidence suggests that impaired gut health may also be a risk factor for SNHL. Inflammatory bowel disease (IBD), type 2 diabetes, diet-induced obesity (DIO), and high-fat diet (HFD) all show links to hearing loss. Previous studies have shown that a HFD can result in microangiopathy, impaired insulin signalling, and oxidative stress in the inner ear. A HFD can also induce pathological shifts in gut microbiota and affect intestinal barrier (IB) integrity, leading to a leaky gut. A leaky gut can result in chronic systemic inflammation, which may affect extraintestinal organs. Here, we postulate that changes in gut microbiota resulting from a chronic HFD and DIO may cause a systemic inflammatory response that can compromise the permeability of the blood-labyrinth barrier (BLB) in the inner ear, thus inducing cochlear inflammation and hearing deficits.

Increased Fetal Cardiovascular Disease Risk: Potential Synergy Between Gestational Diabetes Mellitus and Maternal Hypercholesterolemia

Cardiovascular diseases (CVD) remain a major cause of death worldwide. Evidence suggests that the risk for CVD can increase at the fetal stages due to maternal metabolic diseases, such as gestational diabetes mellitus (GDM) and maternal supraphysiological hypercholesterolemia (MSPH). GDM is a hyperglycemic, inflammatory, and insulin-resistant state that increases plasma levels of free fatty acids and triglycerides, impairs endothelial vascular tone regulation, and due to the increased nutrient transport, exposes the fetus to the altered metabolic conditions of the mother. MSPH involves increased levels of cholesterol (mainly as low-density lipoprotein cholesterol) which also causes endothelial dysfunction and alters nutrient transport to the fetus. Despite that an association has already been established between MSPH and increased CVD risk, however, little is known about the cellular processes underlying this relationship. Our knowledge is further obscured when the simultaneous presentation of MSPH and GDM takes place. In this context, GDM and MSPH may substantially increase fetal CVD risk due to synergistic impairment of placental nutrient transport and endothelial dysfunction. More studies on the separate and/or cumulative role of both processes are warranted to suggest specific treatment options.

Redox regulation of hemodynamics response to diadenosine tetraphosphate an agonist of P2 receptors and renal function in diet-induced hypercholesterolemic rats

Hypercholesterolemia and oxidative stress may lead to disturbances in the renal microvasculature in response to vasoactive agents, including P2 receptors (P2R) agonists. We investigated the renal microvascular response to diadenosine tetraphosphate (Ap₄A), an agonist of P2R, in diet‐induced hypercholesteremic rats over 28 days, supplemented in the last 10 days with tempol (2 mM) or DL‐buthionine‐(S,R)‐sulfoximine (BSO, 20 mM) in the drinking water. Using laser Doppler flowmetry, renal blood perfusion in the cortex and medulla (CBP, MBP) was measured during the infusion of Ap₄A. This induced a biphasic response in the CBP: a phase of rapid decrease was followed by one of rapid increase extended for 30 min in both the normocholesterolemic and hypercholesterolemic rats. The phase of decreased CBP was not affected by tempol or BSO in either group. Early and extended increases in CBP were prevented by tempol in the hypercholesterolemia rats, while, in the normocholesterolemic rats, only the extended increase in CBP was affected by tempol; BSO prevented extended increase in CBP in normocholesterolemic rats. MBP response is not affected by hypercholesterolemia. The hypercholesterolemic rats were characterized by increased urinary albumin and 8‐isoPGF_2α excretion. Moreover, BSO increased the urinary excretion of nephrin in the hypercholesterolemic rats but, similar to tempol, did not affect the excretion of albumin in their urine. The results suggest the important role of redox balance in the extracellular nucleotide regulation of the renal vasculature and glomerular injury in hypercholesterolemia.

Influence of cardiometabolic comorbidities on myocardial function, infarction, and cardioprotection: Role of cardiac redox signaling

The morbidity and mortality from cardiovascular diseases (CVD) remain high. Metabolic diseases such as obesity, hyperlipidemia, diabetes mellitus (DM), non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) as well as hypertension are the most common comorbidities in patients with CVD. These comorbidities result in increased myocardial oxidative stress, mainly from increased activity of nicotinamide adenine dinucleotide phosphate oxidases, uncoupled endothelial nitric oxide synthase, mitochondria as well as downregulation of antioxidant defense systems. Oxidative and nitrosative stress play an important role in ischemia/reperfusion injury and may account for increased susceptibility of the myocardium to infarction and myocardial dysfunction in the presence of the comorbidities. Thus, while early reperfusion represents the most favorable therapeutic strategy to prevent ischemia/reperfusion injury, redox therapeutic strategies may provide additive benefits, especially in patients with heart failure. While oxidative and nitrosative stress are harmful, controlled release of reactive oxygen species is however important for cardioprotective signaling. In this review we summarize the current data on the effect of hypertension and major cardiometabolic comorbidities such as obesity, hyperlipidemia, DM, NAFLD/NASH on cardiac redox homeostasis as well as on ischemia/reperfusion injury and cardioprotection. We also review and discuss the therapeutic interventions that may restore the redox imbalance in the diseased myocardium in the presence of these comorbidities.

Beneficial Effect of Statin Therapy on Arterial Stiffness

Arterial stiffness describes the increased rigidity of the arterial wall that occurs as a consequence of biological aging and several diseases. Numerous studies have demonstrated that parameters to assess arterial stiffness, especially pulse-wave velocity, are predictive of those individuals that will suffer cardiovascular morbidity and mortality. Statin therapy may be a pharmacological strategy to improve arterial elasticity. It has been shown that the positive benefits of statin therapy on cardiovascular disease is attributable not only to their lipid-lowering capacity but also to various pleiotropic effects, such as their anti-inflammatory, antiproliferative, antioxidant, and antithrombotic properties. Additionally, statins reduce endothelial dysfunction, improve vascular and myocardial remodeling, and stabilize atherosclerotic plaque. The aim of the present review was to summarize the evidence from human studies showing the effects of statins on arterial stiffness.

A Three-Month Consumption of Eggs Enriched with ω-3, ω-5 and ω-7 Polyunsaturated Fatty Acids Significantly Decreases the Waist Circumference of Subjects at Risk of Developing Metabolic Syndrome: A Double-Blind Randomized Controlled Trial

Alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), rumenic acid (RmA), and punicic acid (PunA) are claimed to influence several physiological functions including insulin sensitivity, lipid metabolism and inflammatory processes. In this double-blind randomized controlled trial, we investigated the combined effect of ALA, DHA, RmA and PunA on subjects at risk of developing metabolic syndrome. Twenty-four women and men were randomly assigned to two groups. Each day, they consumed two eggs enriched with oleic acid (control group) or enriched with ALA, DHA, RmA, and PunA (test group) for 3 months. The waist circumference decreased significantly (−3.17 cm; p < 0.001) in the test group. There were no major changes in plasma insulin and blood glucose in the two groups. The dietary treatments had no significant effect on endothelial function as measured by peripheral arterial tonometry, although erythrocyte nitrosylated hemoglobin concentrations tended to decrease. The high consumption of eggs induced significant elevations in plasma low-density lipoprotein (LDL)- and high-density lipoprotein (HDL)-cholesterol (p < 0.001), which did not result in any change in the LDL/HDL ratio in both groups. These results indicate that consumption of eggs enriched with ALA, DHA, RmA and PunA resulted in favorable changes in abdominal obesity without affecting other factors of the metabolic syndrome.

Effects of Orlistat/Phentermine versus Phentermine on Vascular Endothelial Cell Function in Obese and Overweight Adults: A Randomized, Double-Blinded, Placebo-Controlled Trial

BACKGROUND

In clinical practice, concomitant treatment of orlistat with phentermine is commonly used off-label. However, clinical trials have not been performed to evaluate whether their combination improves metabolic parameters and cardiovascular risk factors other than weight loss. Therefore, we aimed to compare the efficacy of concomitant administration of orlistat and phentermine versus phentermine alone on the endothelial cell function in overweight and obese adults with back pain.

METHODS

We conducted a 12-week, double-blinded, placebo-controlled clinical trial involving 114 patients with a body mass index of ≥30 (obese) or ≥27 (overweight) with weight-related comorbidities. We randomly assigned patients in a 1:1 ratio to receive orlistat (120mg) three times daily and phentermine (37.5mg) once daily, or a placebo three times daily and phentermine (37.5mg) once daily. Primary endpoint was changes in endothelium-dependent vasodilatation measured using ultrasound assessment of flow-mediated dilatation (FMD). Differences within groups after intervention were compared using the paired t-test or Wilcoxon signed-rank test. Differences in changes between the groups were calculated using an analysis of covariance after adjusting for each baseline value.

RESULTS

Mean weight loss during the 12-week study period was 6.1kg in the orlistat/phentermine group and in the placebo/phentermine group. Adjusted mean changes in total and non-high-density lipoprotein cholesterol were significantly greater in the orlistat/phentermine group than in the placebo/phentermine group. Adjusted mean changes in endothelium-dependent FMD were significantly greater in the orlistat/phentermine group than in the placebo/phentermine group (4.97±0.98% vs 2.05±0.99%, respectively; p=0.038). Changes in endothelium-independent nitroglycerin-mediated dilatation were not significantly different between the groups.

CONCLUSION

Orlistat/phentermine significantly improved the vascular endothelial cell function compared with phentermine alone. Orlistat might have beneficial effects on the decrease of the risk of cardiovascular disease, especially in overweight and obese patients with comorbidities.

TRIAL REGISTRATION

ClinicalTrails.gov number, NCT03675191.

Modulatory effects of BPC 157 on vasomotor tone and the activation of Src-Caveolin-1-endothelial nitric oxide synthase pathway

BPC 157-activated endothelial nitric oxide synthase (eNOS) is associated with tissue repair and angiogenesis as reported in previous studies. However, how BPC 157 regulates the vasomotor tone and intracellular Src-Caveolin-1 (Cav-1)-eNOS signaling is not yet clear. The present study demonstrated a concentration-dependent vasodilation effect of BPC 157 in isolated rat aorta. Attenuation of this vasodilation effect in the absence of endothelium suggested an endothelium-dependent vasodilation effect of BPC 157. Although slightly increased vasorelaxation in aorta without endothelium was noticed at high concentration of BPC 157, there was no direct relaxation effect on three-dimensional model made of vascular smooth muscle cells. The vasodilation effect of BPC 157 was nitric oxide mediated because the addition of L-NAME or hemoglobin inhibited the vasodilation of aorta. Nitric oxide generation was induced by BPC 157 as detected by intracellular DFA-FM DA labeling which was capable of promoting the migration of vascular endothelial cells. BPC 157 enhanced the phosphorylation of Src, Cav-1 and eNOS which was abolished by pretreatment with Src inhibitor, confirming the upstream role of Src in this signal pathway. Activation of eNOS required the released binding with Cav-1 in advance. Co-immunoprecipitation analysis revealed that BPC 157 could reduce the binding between Cav-1 and eNOS. Together, the present study demonstrates that BPC 157 can modulate the vasomotor tone of an isolated aorta in a concentration- and nitric oxide-dependent manner. BPC 157 can induce nitric oxide generation likely through the activation of Src-Cav-1-eNOS pathway.

Impact of Lifestyles (Diet and Exercise) on Vascular Health: Oxidative Stress and Endothelial Function

Healthy lifestyle and diet are associated with significant reduction in risk of obesity, type 2 diabetes, and cardiovascular diseases. Oxidative stress and the imbalance between prooxidants and antioxidants are linked to cardiovascular and metabolic diseases. Changes in antioxidant capacity of the body may lead to oxidative stress and vascular dysfunction. Diet is an important source of antioxidants, while exercise offers many health benefits as well. Recent findings have evidenced that diet and physical factors are correlated to oxidative stress. Diet and physical factors have debatable roles in modulating oxidative stress and effects on the endothelium. Since endothelium and oxidative stress play critical roles in cardiovascular and metabolic diseases, dietary and physical factors could have significant implications on prevention of the diseases. This review is aimed at summarizing the current knowledge on the impact of diet manipulation and physical factors on endothelium and oxidative stress, focusing on cardiovascular and metabolic diseases. We discuss the friend-and-foe role of dietary modification (including different diet styles, calorie restriction, and nutrient supplementation) on endothelium and oxidative stress, as well as the potential benefits and concerns of physical activity and exercise on endothelium and oxidative stress. A fine balance between oxidative stress and antioxidants is important for normal functions in the cells and interfering with this balance may lead to unfavorable effects. Further studies are needed to identify the best diet composition and exercise intensity.

Compression stockings attenuate the expression of proteins associated with vascular damage in human varicose veins

OBJECTIVE

The objective of this study was to analyze whether compression stocking therapy in the human varicose vein wall may change the levels of biomarkers associated with vein insufficiency.

METHODS

Dilated collateral varicose vein samples were obtained from patients showing chronic venous disease (class 2 of the Clinical, Etiology, Anatomy, and Pathophysiology classification). Before elective surgery, 12 patients underwent compression stocking therapy (for 1 month) and 9 patients did not (control group). Expression levels of biomarkers associated with endothelial functionality (nitric oxide synthase 3), inflammation (interleukin-6, interleukin-10), oxidative stress (Gp91^phox subunit of NADPH oxidase), and coagulation (factor Xa) were determined. P-selectin, an inflammatory and thrombosis-related biomarker, was also measured.

RESULTS

Compression stockings increased the content of nitric oxide synthase 3 (control, 16.48 [16.04-17.40] AU; compression, 83.71 [67.70-91.85] AU; P < .001) in the varicose vein wall that was accompanied by reduction of both interleukin-6 levels (control, 38.72 [33.48-48.52] pg/μg protein; compression, 14.49 [11.05-17.41] pg/μg protein; P = .001) and the expression of Gp91^phox subunit of NADPH oxidase (control, 63.24 [53.79-77.03] AU; compression, 36.85 [35.66-52.27] AU; P < .010). P-selectin (control, 77.37 [61.86-85.00] AU; compression, 54.31 [49.60-67.50] AU; P = .017) and factor Xa (control, 90.78 [75.02-100.00] AU; compression, 14.50 [13.77-36.20] AU; P < .001) were also reduced in the varicose vein wall of compression stocking-treated patients. However, P-selectin lost its statistical significance after adjustment by dyslipidemia.

CONCLUSIONS

In the varicose vein wall, compression stocking therapy improved the content levels of biomarkers associated with endothelial functionality, inflammation, oxidative stress, and coagulation.

Clopidogrel or prasugrel reduces mortality and lessens cardiovascular damage from acute myocardial infarction in hypercholesterolemic male rats

AIMS

Hypercholesterolemia is a hazard for increasing susceptibility of the heart to myocardial infarction (MI) by inducing platelet hyperaggregability. Clopidogrel and prasugrel have documented cardioprotective effects in clinical studies. Herein, we investigated whether clopidogrel and prasugrel could protect against isoproterenol-induced acute MI (A-MI) under hypercholesterolemic conditions in rats.

MAIN METHODS

Dietary hypercholesterolemic rats were subjected to acute doses of isoproterenol. Serum lipids, inflammatory markers, aortic endothelin1 and endothelial nitric oxide synthase (eNOS) mRNAs expression and immunexpression of BCL2 were determined.

KEY FINDINGS

Hypercholesterolemic rats showed infiltration of inflammatory cells and reduction in aortic wall thickness, deposition of fibrous tissue between cardiac muscle fibers. Protective doses of prasugrel or clopidogrel for 28 days before A-MI increased survival, amended the ECG parameters -including ST segment elevation- and improved the histopathological picture in hypercholesterolemic rats. This was coupled with reductions in platelet aggregation, creatine kinase-MB activity, endothelin 1, systemic inflammation and cardiac lipid peroxidation and increment in aortic eNOS expression. Clopidogrel and prasugrel groups showed enhanced BCL2 expression in cardiac fibers and aortic wall.

SIGNIFICANCE

Prasugrel and clopidogrel protected against A-MI via anti-aggregatory and anti-inflammatory effects. These results add to the value of these drugs in correcting cardiovascular dysfunction in patients vulnerable to A-MI after confirmation by appropriate human studies.

Role of Caveolin-1 in Diabetes and Its Complications

It is estimated that in 2017 there were 451 million people with diabetes worldwide. These figures are expected to increase to 693 million by 2045; thus, innovative preventative programs and treatments are a necessity to fight this escalating pandemic disorder. Caveolin-1 (CAV1), an integral membrane protein, is the principal component of caveolae in membranes and is involved in multiple cellular functions such as endocytosis, cholesterol homeostasis, signal transduction, and mechanoprotection. Previous studies demonstrated that CAV1 is critical for insulin receptor-mediated signaling, insulin secretion, and potentially the development of insulin resistance. Here, we summarize the recent progress on the role of CAV1 in diabetes and diabetic complications.

Synthetic apolipoprotein A-I mimetic peptide 4F protects hearts and kidneys after myocardial infarction

Patients undergoing coronary angiography after myocardial infarction (MI) often develop cardiac and renal dysfunction. We hypothesized that the apolipoprotein A-I mimetic peptide 4F (4F) would prevent those complications. Male Wistar rats were fed a high-cholesterol diet for 8 days. The rats were then anesthetized with isoflurane and randomly divided into five groups: a control group (sham-operated rats), and four groups of rats induced to MI by left coronary artery ligation, the rats in three of those groups being injected 6 h later, with the nonionic contrast agent iopamidol, 4F, and iopamidol plus 4F, respectively. At postprocedure hour 24, we performed the following experiments/tests (n = 8 rats/group): metabolic cage studies; creatinine clearance studies; analysis of creatinine, urea, sodium, potassium, triglycerides, total cholesterol, very low-, low- and high-density lipoproteins (VLDL, LDL, and HDL); immunohistochemistry; histomorphometry; Western blot analysis; and transmission electron microscopy. In another set of experiments (n = 8 rats/group), also performed at postprocedure hour 24, we measured mean arterial pressure, heart rate, heart rate variability, echocardiographic parameters, left ventricular systolic pressure, and left ventricular end-diastolic pressure. 4F protected against MI-induced increases in total cholesterol, triglycerides, and LDL; increased HDL levels; reversed autonomic and cardiac dysfunction; decreased the myocardial ischemic area; minimized renal and cardiac apoptosis; protected mitochondria; and strengthened endothelia possibly by minimizing Toll-like receptor 4 upregulation (thus restoring endothelial nitric oxide synthase protein expression) and by upregulating vascular endothelial growth factor protein expression. 4F-treated animals showed signs of cardiac neovascularization. The nitric oxide-dependent cardioprotection and renoprotection provided by 4F could have implications for post-MI treatment.

Caveolin-1 in Stroke Neuropathology and Neuroprotection: A Novel Molecular Therapeutic Target for Ischemic-Related Injury

Cardiovascular disease and associated cerebral stroke are a global epidemic attributed to genetic and epigenetic factors, such as diet, life style and an increasingly sedentary existence due to technological advances in both the developing and developed world. There are approximately 5.9 million stroke-related deaths worldwide annually. Current epidemiological data indicate that nearly 16.9 million people worldwide suffer a new or recurrent stroke yearly. In 2014 alone, 2.4% of adults in the United States (US) were estimated to experience stroke, which is the leading cause of adult disability and the fifth leading cause of death in the US There are 2 main types of stroke: Hemorrhagic (HS) and ischemic stroke (IS), with IS occurring more frequently. HS is caused by intra-cerebral hemorrhage mainly due to high blood pressure, while IS is caused by either embolic or thrombotic stroke. Both result in motor impairments, numbness or abnormal sensations, cognitive deficits, and mood disorders (e.g. depression). This review focuses on the 1) pathophysiology of stroke (neuronal cell loss, defective blood brain barrier, microglia activation, and inflammation), 2) the role of the membrane protein caveolin- 1 (Cav-1) in normal brain physiology and stroke-induced changes, and, 3) we briefly discussed the potential therapeutic role of Cav-1 in recovery following stroke.

Redox Regulation of the Microcirculation

The microcirculation maintains tissue homeostasis through local regulation of blood flow and oxygen delivery. Perturbations in microvascular function are characteristic of several diseases and may be early indicators of pathological changes in the cardiovascular system and in parenchymal tissue function. These changes are often mediated by various reactive oxygen species and linked to disruptions in pathways such as vasodilation or angiogenesis. This overview compiles recent advances relating to redox regulation of the microcirculation by adopting both cellular and functional perspectives. Findings from a variety of vascular beds and models are integrated to describe common effects of different reactive species on microvascular function. Gaps in understanding and areas for further research are outlined. © 2020 American Physiological Society. Compr Physiol 10:229-260, 2020.

Statin-Induced Nitric Oxide Signaling: Mechanisms and Therapeutic Implications

In addition to their cholesterol-lowering effects, statins are associated with pleiotropic effects including improvements in heart failure (HF), reduced blood pressure, prevention of the rupture of atherosclerotic plaques and improved angiogenesis. In addition to these cardiovascular benefits, statins have been implicated in the treatment of neurological injuries, cancer, sepsis, and cirrhosis. These cholesterol-independent beneficial effects of statins are predominantly mediated through signaling pathways leading to increased production and bioavailability of nitric oxide (NO). In this review, the mechanistic pathways and therapeutic effects of statin-mediated elevations of NO are described and discussed.

Oxidative Stress in Response to Saturated Fat Ingestion Is Linked to Insulin Resistance and Hyperandrogenism in Polycystic Ovary Syndrome

CONTEXT

Oxidative stress and insulin resistance are often present in polycystic ovary syndrome (PCOS).

OBJECTIVE

We determined the effect of saturated fat ingestion on leukocytic reactive oxygen species (ROS) generation, p47phox expression, and circulating thiobarbituric acid-reactive substances (TBARS) in women with PCOS.

DESIGN

Cross-sectional study.

SETTING

Academic medical center.

PATIENTS

Twenty women of reproductive age with PCOS (10 lean, 10 with obesity) and 19 ovulatory control subjects (10 lean, 9 with obesity).

MAIN OUTCOME MEASURES

ROS generation and p47phox mRNA and protein content were quantified in leukocytes, and TBARS was measured in plasma from blood drawn while the subjects were fasting and 2, 3, and 5 hours after saturated fat ingestion. Insulin sensitivity was derived from an oral glucose tolerance test (ISOGTT). Androgen secretion was assessed from blood drawn while the subjects were fasting and 24, 48, and 72 hours after human chorionic gonadotropin (HCG) administration.

RESULTS

Regardless of weight class, women with PCOS exhibited lipid-induced increases in leukocytic ROS generation and p47phox mRNA and protein content as well as plasma TBARS compared with lean control subjects. Both PCOS groups exhibited lower ISOGTT and greater HCG-stimulated androgen secretion compared with control subjects. The ROS generation, p47phox, and TBARS responses were negatively correlated with ISOGTT and positively correlated with HCG-stimulated androgen secretion.

CONCLUSION

In PCOS, increases in ROS generation, p47phox gene expression, and circulating TBARS in response to saturated fat ingestion are independent of obesity. Circulating mononuclear cells and excess adipose tissue are separate and distinct contributors to oxidative stress in this disorder.

The Mystery behind the Pineal Gland: Melatonin Affects the Metabolism of Cholesterol

Melatonin may be considered a cardioprotective agent. Since atherogenesis is partly associated with the metabolism of lipoproteins, it seems plausible that melatonin affects cardiovascular risk by modulating the metabolism of cholesterol and its subfractions. Moreover, cholesterol-driven atherogenesis can be hypothetically reduced by melatonin, mainly due to the minimalization of harmful reactions triggered in the cardiovascular system by the reactive oxygen species-induced toxic derivatives of cholesterol. In this review, we attempted to summarize the available data on the hypolipemizing effects of melatonin, with some emphasis on the molecular mechanisms underlying these reactions. We aimed to attract readers' attention to the numerous gaps of knowledge present in the reviewed field and the essential irrelevance between the findings originating from different sources: clinical observations and in vitro mechanistic and molecular studies, as well as preclinical experiments involving animal models. Overall, such inconsistencies make it currently impossible to give a reliable opinion on the action of melatonin on the metabolism of lipoproteins.

Atherosclerosis: integration of its pathogenesis as a self-perpetuating propagating inflammation: a review

This review proposes that the development of the atherosclerotic plaque is critically dependent on its inflammatory components forming a self-perpetuating and propagating positive feedback loop. The components involved are: (1) LDL oxidation, (2) activation of the endothelium, (3) recruitment of inflammatory monocytes, (4) macrophage accumulation, which induces LDL oxidation, and (5) macrophage generation of inflammatory mediators, which also activate the endothelium. Through these stages, the positive feedback loop is formed, which generates and promotes expansion of the atherosclerotic process. To illustrate this dynamic of lesion development, the author previously produced a computer simulation, which allowed realistic modelling. This hypothesis on atherogenesis can explain the existence and characteristic focal morphology of the atherosclerotic plaque. Each of the components contributing to the feedback loop is discussed. Many of these components also contain subsidiary positive feedback loops, which could exacerbate the overall process.

Resveratrol and Vascular Function

Resveratrol increases the production of nitric oxide (NO) in endothelial cells by upregulating the expression of endothelial NO synthase (eNOS), stimulating eNOS enzymatic activity, and preventing eNOS uncoupling. At the same time, resveratrol inhibits the synthesis of endothelin-1 and reduces oxidative stress in both endothelial cells and smooth muscle cells. Pathological stimuli-induced smooth muscle cell proliferation, vascular remodeling, and arterial stiffness can be ameliorated by resveratrol as well. In addition, resveratrol also modulates immune cell function, inhibition of immune cell infiltration into the vascular wall, and improves the function of perivascular adipose tissue. All these mechanisms contribute to the protective effects of resveratrol on vascular function and blood pressure in vivo. Sirtuin 1, AMP-activated protein kinase, and estrogen receptors represent the major molecules mediating the vascular effects of resveratrol.

Lipoprotein Apheresis Acutely Reverses Coronary Microvascular Dysfunction in Patients With Severe Hypercholesterolemia

OBJECTIVES

This study evaluated whether lipoprotein apheresis produces immediate changes in resting perfusion in subjects with severe hypercholesterolemia, and whether there is a difference in the response between peripheral and coronary microcirculations.

BACKGROUND

Lipoprotein apheresis is used in patients with severe hypercholesterolemia to reduce plasma levels of low-density lipoprotein cholesterol.

METHODS

Quantitative contrast-enhanced ultrasound perfusion imaging of the myocardium at rest and skeletal muscle at rest and during calibrated contractile exercise was performed before and immediately after lipoprotein apheresis in 8 subjects with severe hypercholesterolemia, 7 of whom had a diagnosis of familial hypercholesterolemia. Myocardial perfusion imaging was also performed in 14 normal control subjects. Changes in myocardial work and left ventricular function were assessed by echocardiography. Ex vivo ovine coronary and femoral artery ring tension assays were assessed in the presence of pre- and post-apheresis plasma.

RESULTS

Apheresis acutely decreased low-density lipoprotein cholesterol (234.9 ± 103.2 mg/dl vs. 67.1 ± 49.5 mg/dl; p < 0.01) and oxidized phospholipid on apolipoprotein B-100 (60.2 ± 55.2 nmol/l vs. 47.0 ± 24.5 nmol/l; p = 0.01), and acutely increased resting myocardial perfusion (55.1 [95% confidence interval: 77.2 to 73.1] IU/s vs. 135 [95% confidence interval: 81.2 to 189.6] IU/s; p = 0.01), without changes in myocardial work. Myocardial longitudinal strain improved in those subjects with reduced pre-apheresis function. Skeletal muscle perfusion at rest and during contractile exercise was unchanged by apheresis. Acetylcholine-mediated dilation of ex vivo ovine coronary but not femoral arteries was impaired in pre-apheresis plasma and was completely reversed in post-apheresis plasma.

CONCLUSIONS

Lipoprotein apheresis produces an immediate improvement in coronary microvascular function, which increases myocardial perfusion and normalizes endothelial-dependent vasodilation. These changes are not observed in the periphery. (Acute Microvascular Changes With LDL Apheresis; NCT02388633).

Maternal supraphysiological hypercholesterolemia associates with endothelial dysfunction of the placental microvasculature

Maternal physiological or supraphysiological hypercholesterolemia (MPH, MSPH) occurs during pregnancy. MSPH is associated with foetal endothelial dysfunction and atherosclerosis. However, the potential effects of MSPH on placental microvasculature are unknown. The aim of this study was to determine whether MSPH alters endothelial function in the placental microvasculature both ex vivo in venules and arterioles from the placental villi and in vitro in primary cultures of placental microvascular endothelial cells (hPMEC). Total cholesterol < 280 mg/dL indicated MPH, and total cholesterol ≥280 mg/dL indicated MSPH. The maximal relaxation to histamine, calcitonin gene-related peptide and adenosine was reduced in MSPH venule and arteriole rings. In hPMEC from MSPH placentas, nitric oxide synthase (NOS) activity and L-arginine transport were reduced without changes in arginase activity or the protein levels of endothelial NOS (eNOS), human cationic amino acid 1 (hCAT-1), hCAT-2A/B or arginase II compared with hPMEC from MPH placentas. In addition, it was shown that adenosine acts as a vasodilator of the placental microvasculature and that NOS is active in hPMEC. We conclude that MSPH alters placental microvascular endothelial function via a NOS/L-arginine imbalance. This work also reinforces the concept that placental endothelial cells from the macro- and microvasculature respond differentially to the same pathological condition.

Microparticles from Patients Undergoing Percutaneous Coronary Intervention Impair Vasodilatation by Uncoupling Endothelial Nitric Oxide Synthase

OBJECTIVES

Percutaneous coronary interventions (PCIs) save countless acute myocardial infarction (AMI) patients. However, endothelial injury is still an inevitable complication. Circulating microparticles (MPs) play important roles in vascular dysfunction. Whether PCI affects function of MPs remains unclear.

METHODS

MPs were obtained from AMI patients (n = 38) both preoperatively and 24 h after PCI, and healthy subjects (n = 20). MPs origins were tested by flow cytometry. Rat thoracic aortas were incubated with MPs to determine the effects of MPs on phosphorylation of endothelial nitric oxide synthase (eNOS), caveolin-1 expression, eNOS association with heat shock protein 90 (Hsp90), generation of nitric oxide (NO) and superoxide anion (O2), and endothelial-dependent vasodilatation.

RESULTS

Compared with healthy subjects, MP concentrations increased in AMI patients. Undergoing PCI had no further effect on MPs concentration, but it results in increased endothelial-derived MPs proportion and decreased platelet-derived MP ratio. MPs from AMI patients decreased eNOS phosphorylation at Ser1177, increased eNOS phosphorylation at T495 and caveolin-1 expression, decreased eNOS association with Hsp90, decreased NO production but increased (O2) generation, damaged endothelial-dependent vasodilatation. All of these effects of MPs were strengthened by PCI.

CONCLUSIONS

PCI further enhances the vascular injury effect of MPs. Circulating MPs may be a potential therapeutic target for patients undergoing PCI.

Protective Role of Perivascular Adipose Tissue in Endothelial Dysfunction and Insulin-Induced Vasodilatation of Hypercholesterolemic LDL Receptor-Deficient Mice

Background: Endothelial dysfunction plays a pivotal role in the initiation of atherosclerosis. Vascular insulin resistance might contribute to a reduction in endothelial nitric oxide (NO) production, leading to impaired endothelium-dependent relaxation in cardiometabolic diseases. Because perivascular adipose tissue (PVAT) controls endothelial function and NO bioavailability, we hypothesized a role for this fat deposit in the vascular complications associated with the initial stages of atherosclerosis. Therefore, we investigated the potential involvement of PVAT in the early endothelial dysfunction in hypercholesterolemic LDL receptor knockout mice (LDLr-KO).

Methods: Thoracic aortas with and without PVAT were isolated from 4-month-old C57BL/6J (WT) and LDLr-KO mice. The contribution of PVAT to relaxation responses to acetylcholine, insulin, and sodium nitroprusside was investigated. Western blotting was used to examine endothelial NO synthase (eNOS) and adiponectin expression, as well the insulin signaling pathway in aortic PVAT.

Results: PVAT-free aortas of LDLr-KO mice exhibited impaired acetylcholine- and insulin-induced relaxation compared with those of WT mice. Both vasodilatory responses were restored by the presence of PVAT in LDLr-KO mice, associated with enhanced acetylcholine-induced NO levels. PVAT did not change vasodilatory responses to acetylcholine and insulin in WT mice, while vascular relaxation evoked by the NO donor sodium nitroprusside was not modified by either genotype or PVAT. The expression of insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), AKT, ERK1/2, phosphorylation of AKT (Ser473) and ERK1/2 (Thr202/Tyr204), and adiponectin was similar in the PVAT of WT and LDLr-KO mice, suggesting no changes in PVAT insulin signaling. However, eNOS expression was enhanced in the PVAT of LDLr-KO mice, while eNOS expression was less abundant in PVAT-free aortas.

Conclusion: These results suggest that elevated eNOS-derived NO production in aortic PVAT might be a compensatory mechanism for the endothelial dysfunction and impaired vasodilator action of insulin in hypercholesterolemic LDLr-deficient mice. This protective effect may limit the progression of atherosclerosis in genetic hypercholesterolemia in the absence of an atherogenic diet.

24S-hydroxycholesterol suppresses neuromuscular transmission in SOD1(G93A) mice: A possible role of NO and lipid rafts

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the initial denervation of skeletal muscle and subsequent death of motor neurons. A dying-back pattern of ALS suggests a crucial role for neuromuscular junction dysfunction. In the present study, microelectrode recording of postsynaptic currents and optical detection of synaptic vesicle traffic (FM1-43 dye) and intracellular NO levels (DAF-FM DA) were used to examine the effect of the major brain-derived cholesterol metabolite 24S-hydroxycholesterol (24S-HC, 0.4 μM) on neuromuscular transmission in the diaphragm of transgenic mice carrying a mutant superoxide dismutase 1 (SOD^G93A). We found that 24S-HC suppressed spontaneous neurotransmitter release and neurotransmitter exocytosis during high-frequency stimulation. The latter was accompanied by a decrease in both the rate of synaptic vesicle recycling and activity-dependent enhancement of NO production. Inhibition of NO synthase with L-NAME also attenuated synaptic vesicle exocytosis during high-frequency stimulation and completely abolished the effect of 24S-HC itself. Of note, 24S-HC enhanced the labeling of synaptic membranes with B-subunit of cholera toxin, suggesting an increase in lipid ordering. Lipid raft-disrupting agents (methyl-β-cyclodextrin, sphingomyelinase) prevented the action of 24S-HC on both lipid raft marker labeling and NO synthesis. Together, these experiments indicate that 24S-HC is able to suppress the exocytotic release of neurotransmitter in response to intense activity via a NO/lipid raft-dependent pathway in the neuromuscular junctions of SOD^G93A mice.

The association between elevated serum uric acid levels and islet β-cell function indexes in newly diagnosed type 2 diabetes mellitus: a cross-sectional study

Background

Serum uric acid (UA) has been reported as a risk factor for type 2 diabetes mellitus (T2DM). However, whether serum UA is associated with insulin resistance and insulin secretion, and the effect of gender on it in the case of the existed association, both remain undefined.

Methods

A cross-sectional study was designed and performed, which enrolled a total of 403 newly diagnosed T2DM patients (mean age, 50.21 ± 13.34 years (62.5% males)). Clinical characteristics and islet function indexes of all participants were analyzed based on gender-specific tertiles of serum UA levels. In addition, multiple linear regression analysis was conducted to investigate covariates associated with islet function indexes.

Results

The mean levels of serum UA were 331.05 μmol/L (interquartile range (IQR): 60.6, 400.9 μmol/L) and 267.9 μmol/L (IQR: 204.7, 331.9 μmol/L) in men and women, respectively. The values of insulin secretion indexes involving AUCins30/glu30, AUCins120/glu120 and total insulin disposition index (DI120) in females were significantly higher than those in males. Apart from the homeostasis model assessment insulin resistance of men, serum UA was positively associated with insulin secretion and insulin resistance indexes both in men and women. Multivariable linear regression analysis showed serum UA exerted an independent impact on insulin secretion in females, but not on insulin resistance. In males, islet function was simultaneously affected by serum UA age, body mass index (BMI), and serum lipids.

Conclusion

Serum UA harbored a positive correlation with insulin secretion and insulin resistance indexes in newly diagnosed T2DM patients, which was influenced by gender, BMI, serum lipids. Hence, serum UA may be considered as a predictor for islet function in clinical practice.

Hypercholesterolemia-Induced Loss of Flow-Induced Vasodilation and Lesion Formation in Apolipoprotein E-Deficient Mice Critically Depend on Inwardly Rectifying K+ Channels

BACKGROUND

Hypercholesterolemia-induced decreased availability of nitric oxide (NO) is a major factor in cardiovascular disease. We previously established that cholesterol suppresses endothelial inwardly rectifying K+ (Kir) channels and that Kir2.1 is an upstream mediator of flow-induced NO production. Therefore, we tested the hypothesis that suppression of Kir2.1 is responsible for hypercholesterolemia-induced inhibition of flow-induced NO production and flow-induced vasodilation (FIV). We also tested the role of Kir2.1 in the development of atherosclerotic lesions.

METHODS AND RESULTS

Kir2.1 currents are significantly suppressed in microvascular endothelial cells exposed to acetylated-low-density lipoprotein or isolated from apolipoprotein E-deficient (Apoe-/- ) mice and rescued by cholesterol depletion. Genetic deficiency of Kir2.1 on the background of hypercholesterolemic Apoe-/- mice, Kir2.1+/-/Apoe-/- exhibit the same blunted FIV and flow-induced NO response as Apoe-/- or Kir2.1+/- alone, but while FIV in Apoe-/- mice can be rescued by cholesterol depletion, in Kir2.1+/-/Apoe-/- mice cholesterol depletion has no effect on FIV. Endothelial-specific overexpression of Kir2.1 in arteries from Apoe-/- and Kir2.1+/-/Apoe-/- mice results in full rescue of FIV and NO production in Apoe-/- mice with and without the addition of a high-fat diet. Conversely, endothelial-specific expression of dominant-negative Kir2.1 results in the opposite effect. Kir2.1+/-/Apoe-/- mice also show increased lesion formation, particularly in the atheroresistant area of descending aorta.

CONCLUSIONS

We conclude that hypercholesterolemia-induced reduction in FIV is largely attributable to cholesterol suppression of Kir2.1 function via the loss of flow-induced NO production, whereas the stages downstream of flow-induced Kir2.1 activation appear to be mostly intact. Kir2.1 channels also have an atheroprotective role.

Protective effect of Urtica dioica leaf hydro alcoholic extract against experimentally-induced atherosclerosis in rats

OBJECTIVE

Finding compounds that could be used for prevention of atherosclerosis (AS) is highly desired. The present study evaluated the protective effects of Urtica dioica (UD, commonly known as stinging nettle) leaf ethanolic extract against high-fat diet-induced AS in rats.

MATERIALS AND METHODS

In this study, 40 male adult Sprauge-Dawley rats were randomly allocated to 4 equal groups and treated as follows for 9 consecutive weeks: (1) Normal control (NC; normal rats that were fed with a basic diet); (2) Atherosclerotic rats (AT; which received no particular treatment); (3) Atherosclerotic rats that received 100 mg/kg/day ethanolic extract of UD orally and (4) Atherosclerotic rats that received simvastatin 4 mg/kg/day orally. Atherosclerosis was induced by a high-fat diet accompanied by propylthiouracil and vitamin D3.

RESULTS

Marked hypercholesterolemia and significant increase in LDL-C/HDL-C ratio were observed in rats of AT group. Administration of UD significantly reduced these parameters as compared to AT group (p<0.05 for all cases). In histopathological evaluations of the aortic arch, AT rats showed atherosclerotic lesions, which were markedly ameliorated in rats treated with UD or simvastatin. Simvastatin and UD significantly reduced medial (p<0.05) but not intimal thickness. Increased level of malondialdehyde (MDA) and reduced total antioxidant capacity (TAC) were observed in the aortic arch of AT rats (p<0.05 for all cases). In contrast with simvastatin, UD extract had no significant effect on these parameters.

CONCLUSION

Ethanolic extract of UD prevents establishment of atherosclerotic lesions in rat aorta, which is associated with positive effects on serum lipid profile without significantly affecting antioxidant status.