Nitric oxide and the vascular endothelium

Innovative nitric oxide-releasing nanomaterials: Current progress, trends, challenges, and perspectives in cardiovascular therapies

Cardiovascular diseases remain the leading cause of death worldwide, imposing a substantial impact on healthcare systems due to high morbidity, mortality, and associated economic costs. Nitric oxide (NO), a key signaling molecule in the cardiovascular system, plays a critical role in regulating vascular homeostasis, angiogenesis, and inflammation. Despite its therapeutic potential, direct NO delivery in the cardiovascular system is limited by its reactivity, short half-life, and poor bioavailability. The development of NO-releasing nanomaterials addresses these challenges by enabling controlled, targeted, and sustained NO delivery, mitigating systemic toxicity and improving therapeutic outcomes. This review provides a comprehensive overview of recent advancements in the design, functionalization, and application of NO-releasing nanomaterials for cardiovascular therapies. Key topics include the use of in vitro and in vivo models to evaluate efficacy in conditions such as myocardial ischemia-reperfusion injury, thrombosis, and atherosclerosis, as well as the role of stimuli-responsive systems and hybrid nanomaterials in enhancing delivery precision. Advances in nanotechnology, such as stimuli-responsive systems and hybrid functionalized nanomaterials for targeted delivery, have enhanced the precision and effectiveness of NO therapeutic effects for treating a wide spectrum of cardiovascular conditions. However, challenges like scalable production, biocompatibility, and integration with existing therapies remain. Future research should focus on interdisciplinary approaches to optimize these materials for clinical translation, ensuring accessibility and addressing the global problem of cardiovascular diseases.

Cardioprotection by poloxamer 188 is mediated through increased endothelial nitric oxide production

Ischemia/reperfusion (I/R) injury significantly contributes to the morbidity and mortality associated with cardiac events. Poloxamer 188 (P188), a non-ionic triblock copolymer, has been proposed to mitigate I/R injury by stabilizing cell membranes. However, the underlying mechanisms remain incompletely understood, particularly concerning endothelial cell (EC) function and nitric oxide (NO) production. We employed human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs) and ECs to elucidate the effects of P188 on cellular survival, function, and NO secretion under simulated I/R conditions. iPSC-CMs contractility and iPSC-ECs' NO production were assessed following exposure to P188. Further, an isolated heart model using Brown Norway rats subjected to I/R injury was utilized to evaluate the ex-vivo cardioprotective effects of P188, examining cardiac function and NO production, with and without the administration of a NO inhibitor. In iPSC-derived models, P188 significantly preserved CM contractile function and enhanced cell viability after hypoxia/reoxygenation. Remarkably, P188 treatment led to a pronounced increase in NO secretion in iPSC-ECs, a novel finding demonstrating endothelial protective effects beyond membrane stabilization. In the rat isolated heart model, administration of P188 during reperfusion notably improved cardiac function and reduced I/R injury markers. This cardioprotective effect was abrogated by NO inhibition, underscoring the pivotal role of NO. Additionally, a dose-dependent increase in NO production was observed in non-ischemic rat hearts treated with P188, further establishing the critical function of NO in P188 induced cardioprotection. In conclusion, our comprehensive study unveils a novel role of NO in mediating the protective effects of P188 against I/R injury. This mechanism is evident in both cellular models and intact rat hearts, highlighting the potential of P188 as a therapeutic agent against I/R injury. Our findings pave the way for further investigation into P188's therapeutic mechanisms and its potential application in clinical settings to mitigate I/R-related cardiac dysfunction.

The Cortisol Effect on the NO/cGMP Pathway

Previously, it has been shown that cortisol induces oxidative stress in human platelets, stimulating reactive oxygen species production, superoxide anion formation, lipid peroxidation, and depleting antioxidant defenses. In this study, the cortisol effect on platelet function has been described. Results demonstrate that cortisol stimulates platelet activation and aggregation, leading to CD62P surface exposure and intracellular calcium elevation. Cortisol potentiates its aggregating effect, reducing the level of the powerful anti-aggregating agent nitric oxide (NO). Likewise, cortisol reduces cGMP levels. Moreover, specific inhibitors of the Src/Syk/PI3K/AKT pathways reverse the inhibiting effect of cortisol, partially restoring NO and cGMP levels. Unexpectedly, cortisol stimulates endothelial nitric oxide synthase (eNOS) activity, measured in platelet lysates prepared by whole cells treated with the hormone. The phosphorylation of the Ser1177 eNOS activating-residue is increased by cortisol. The Src/Syk/PI3K/AKT pathways appear to be involved in the phosphorylation of this residue. Moreover, cortisol induces the formation of nitrotyrosine, that can be considered a biomarker for reactive nitrogen species, including peroxynitrite. In conclusion, through these mechanisms, cortisol potentiates its capacity to induce oxidative stress in human platelets.

Nitric oxide in the mechanisms of inhibitory effects of sodium butyrate on colon contractions in a mouse model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a multifactorial disorder, with altered intestinal motility, visceral hypersensitivity, and dysfunction of the gut-brain axis. The aim of our study was to analyze the role of nitric oxide (NO) in the inhibitory effects of sodium butyrate on spontaneous contractility of proximal colon in a mouse model of IBS. IBS was induced by intracolonic infusion of acetic acid in the early postnatal period. Spontaneous contractions of proximal colon segments were studied in isometric conditions. The amplitude and frequency of colon contractions were higher in the IBS group. Sodium butyrate exerted inhibitory effects on colon contractions, which were less pronounced in IBS group. NO donors decreased spontaneous colon contractility and prevented the inhibitory effects of sodium butyrate in control and IBS groups. Nitric oxide synthase (NOS) inhibition by L-NAME increased contractile activity more effective in the control group and decreased the inhibitory action of sodium butyrate. In IBS group, preliminary application of L-NAME did not prevent sodium butyrate action. Our data indicate that butyrate exerts its inhibitory effects on colon motility at least partially through activation of NO synthesis. In the IBS model group, the NO-dependent mechanisms were less effective probably due to downregulation of NOS.

Reducing vasospasm of vein and arterial conduits used in coronary artery bypass surgery: are solutions the solution or is preserved perivascular fat the answer?

The three main conduits used for myocardial revascularization in patients with coronary artery disease (CAD) are the internal thoracic artery (ITA), radial artery (RA) and saphenous vein (SV). In coronary artery bypass grafting (CABG) conduits may be harvested with perivascular adipose tissue (PVAT) intact (pedicled) or removed (skeletonized). Various studies have shown that the patency rate of these bypass grafts may be affected by the preservation or removal of PVAT. Vasospasm is often encountered at harvesting, a condition that has both immediate and long term effects on graft performance. During surgery a variety of antispastic solutions are routinely used on conduits that have anti-contractile and/or vasorelaxant actions. Spasm may be abolished or reduced when PVAT is left intact at harvesting and this is particularly the case for the SV. The protective properties of PVAT are multifactorial, ranging from its mechanical properties in supporting the graft after implantation to the beneficial effect of adipocyte-derived factors. This review aims to outline the possible mechanisms through which preserved PVAT could alleviate vasospasm and improve conduit performance in CABG. Moreover, since preservation of PVAT reduces spasm at and after surgery this review also considers whether antispastic solutions are needed if conduits are harvested with PVAT intact.

A continuous mode of action of nitric oxide in hard-to-heal wound healing

Nitric oxide (NO) is one of the most studied molecules in medical science. The role of NO as an endogenous regulator of inflammation, as an antibacterial agent and as an endogenous gasotransmitter is well established. Even so, despite a plethora of excellent wound healing data, hard-to-heal (chronic) wounds are of epidemic proportions, and still growing in number. However, yet to be established and sorely needed is the identification of a single, continuous NO mechanism of action (MoA), where phase-to-phase variance in the complex sequence of cellular and molecular wound healing may elucidate the potential for placing hard-to-heal wounds on positive healing trajectories. Hence, the objectives of this review were to: identify salient MoAs for NO in each phase of skin wound healing; and to select and validate a single MoA that is both ubiquitous and continuous in NO across acute and hard-to-heal wound sequences, and which potentiates the ability to supplementally motivate and guide the recovery of a hard-to-heal wound onto a positive healing trajectory. The search began by selecting a detailed, multipart wound healing model. Next, as guided by the literature, was the identification of salient NO functionalities for each model segment. These modes of action were then be used to identify and validate a single NO MoA that is continuous across the healing spectrum. Finally, by using the principle of 'super position' of two continuous functions, this acute healing NO MoA solution was compared to a similar solution set describing a hard-to-heal or chronic wound. As both solution sets are continuous in a NO function, the resultant 'overlay' then helped to identify and guide the use of a NO MoA capable of placing any hard-to-heal wound on a positive healing trajectory.

The NITRATE-OCT study-inorganic nitrate reduces in-stent restenosis in patients with stable coronary artery disease: a double-blind, randomised controlled trial

Background

Coronary angioplasty and stent insertion is a first line treatment for patients with coronary artery disease, however it is complicated in the long-term by in-stent restenosis (ISR) in a proportion of patients with an associated morbidity. Despite this, currently there are no effective treatments available for the prevention of ISR. Repeat percutaneous revascularisation carries increased risks of major adverse cardiovascular events and a higher incidence of stent failure. In this study we report the efficacy of dietary inorganic nitrate in the prevention of ISR in a prospective, double-blind, randomised controlled trial.

Methods

NITRATE-OCT is a double-blind, randomised, single-centre, placebo-controlled phase II trial. 300 patients who were planned to undergo percutaneous coronary intervention (PCI) and drug eluting stent (DES) implantation for stable angina were randomised on a 1:1 basis to receive a daily dose of either dietary inorganic nitrate or placebo for 6 months. Block randomisation was used and patients stratified according to diabetes status. The patients then underwent quantitative coronary angiography (QCA) at baseline and at 6 months and optical coherence tomography at 6 months to quantify ISR. The primary endpoint was the QCA quantified decrease of in-stent/in-segment diameter from the baseline measure at 6 months i.e., in-stent and in-segment late-lumen loss (LLL). The study is registered with ClinicalTrials.gov, number NCT02529189.

Findings

From November 1st 2015 and March 31st 2020, NITRATE-OCT enrolled 300 patients with angina, with 150 each randomised to receive 70 mL of nitrate-containing beetroot juice or placebo (nitrate-deplete) juice for 6 months. Procedural characteristics were similar between the groups. The primary endpoint was available in 208 patients: 107 and 101 in the nitrate and placebo groups, respectively. There was a statistically significant effect of inorganic nitrate on both primary endpoints: in-stent LLL decreased by 0.16 mm (95% CI:0.06-0.25; P = 0.001) with mean = 0.09 ± 0.38 mm in the inorganic nitrate group versus 0.24 ± 0.33 mm in the placebo group; (P = 0.0052); and in-segment LLL decreased by 0.24 mm (95% CI:0.12-0.36; P < 0.001) with mean = 0.02 ± 0.52 mm in the inorganic nitrate group and 0.26 ± 0.37 mm in the placebo group (P = 0.0002). Inorganic nitrate treatment was associated with a rise in the plasma nitrate concentration of ∼6.1-fold and plasma nitrite (NO2 -) of ∼2.0-fold at 6 months. These rises were associated with sustained decreases in systolic blood pressure (SBP) at 6 months compared to baseline with a change SBP of -12.06 ± 15.88 mmHg compared to the placebo group of 2.52 ± 14.60 mmHg (P < 0.0001).

Interpretation

In patients who underwent PCI for stable coronary artery disease, a once-a-day oral inorganic nitrate treatment was associated with a significant decrease in both in-stent and in-segment LLL.

Funding

This trial and KSR was funded by the National Institute for Health and Care Research (NIHR) (DRF-2014-07-008) and NIHR ACL, HW and this study were supported by The NIHR Barts Biomedical Research Centre, IC was funded by The North and East London Clinical Research Network, CL, GM were funded by The Barts Charity Cardiovascular Programme MRG00913 and MO was funded by The British Heart Foundation Project Grant PG/19/4/33995.

Mechanosensory entities and functionality of endothelial cells

The endothelial cells of the blood circulation are exposed to hemodynamic forces, such as cyclic strain, hydrostatic forces, and shear stress caused by the blood fluid's frictional force. Endothelial cells perceive mechanical forces via mechanosensors and thus elicit physiological reactions such as alterations in vessel width. The mechanosensors considered comprise ion channels, structures linked to the plasma membrane, cytoskeletal spectrin scaffold, mechanoreceptors, and junctional proteins. This review focuses on endothelial mechanosensors and how they alter the vascular functions of endothelial cells. The current state of knowledge on the dysregulation of endothelial mechanosensitivity in disease is briefly presented. The interplay in mechanical perception between endothelial cells and vascular smooth muscle cells is briefly outlined. Finally, future research avenues are highlighted, which are necessary to overcome existing limitations.

Hydroxypropyl methylcellulose reinforced bilayer hydrogel dressings containing L-arginine-modified polyoxometalate nanoclusters to promote healing of chronic diabetic wounds

Diabetes-related slow healing of wounds is primarily driven by bacterial infections and angiogenesis disorder and presents a substantial hurdle in clinical treatment. To solve the above problems, an advanced multifunctional hydrogel system based on natural polymer was created here to facilitate wound healing in patients with chronic diabetes. The prepared dressing was composed of an outer hydrogel containing polyvinyl alcohol and hydroxypropyl methyl cellulose in dimethyl sulfoxide and water as binary solvents, and an inner hydrogel containing chitosan quaternary ammonium salt, flaxseed gum, and polyvinyl alcohol. Thus, a polysaccharide based bilayer hydrogel (BH) with superior mechanical strength and biocompatibility was created. This bilayer hydrogel could easily bind to dynamic tissue surfaces, thereby generating a protective barrier. Meanwhile, L-arginine-modified polyoxometalate (POM@L-Arg) nanoclusters were loaded in the inner hydrogel. They released NO when stimulated by the peroxide microenvironment of diabetic wounds. NO as a signal molecule regulated vascular tension and promoted cell proliferation and migration. Additionally, because of the synergistic effect of NO and the chitosan quaternary ammonium salt, the hydrogel system exhibited excellent antibacterial performance. The NO released reduced the levels of proinflammatory factors IL-6 and TNF-α in the diabetic wounds, which thus accelerated wound healing. In short, BH + POM@L-Arg is expected to serve as an ideal wound dressing as it exerts a good promotion effect on diabetes-related wound healing.

The interaction between dietary nitrates/nitrites intake and gut microbial metabolites on metabolic syndrome: a cross-sectional study

Background

Metabolic syndrome (MetS) prevalence has increased globally.The evidence shows thatdiet and gut microbial metabolites includingtrimethylamine N-oxide (TMAO) and kynurenine (KYN) play an important role in developing MetS. However, there is a lack of evidence on associations between between diet and these metabolites. This study aimed to investigate the interaction between dietary nitrate/nitrite and gut microbial metabolites (TMAO, KYN) on MetS and its components.

Methods

This cross-sectional study included 250 adults aged 20-50 years. Dietary intake was assessed using food frequency questionnaires (FFQ), and serum TMAO and KYN levels were measured. MetS was defined usingthe National Cholesterol Education Program Adult Treatment Panel (NCEP ATP III) criteria.

Result

The ATPIII index revealed an 11% prevalence of metabolic syndrome among the study participants. After adjusting for confounders, significant positive interactions were found: High animal-source nitrate intake and high TMAO levels with elevated triglycerides (TG) (p interaction = 0.07) and abdominal obesity (p interaction = 0.08). High animal-source nitrate intake and high KYN levels with increased TG (p interaction = 0.01) and decreased high-density lipoprotein cholesterol (HDL) (p interaction = 0.01).Individuals with high animal-source nitrite intake and high TMAO levels showed increased risk of hypertriglyceridemia (OR: 1.57, 95%CI: 0.35-2.87, p = 0.05), hypertension (OR: 1.53, 95%CI: 0.33-2.58, p = 0.06), and lower HDL (OR: 1.96, 95%CI: 0.42-2.03, p = 0.04). Similarly, high animal-source nitrite intake with high KYN levels showed lower HDL (OR: 2.44, 95%CI: 1.92-3.89, p = 0.07) and increased risk of hypertension (OR: 2.17,95%CI: 1.69-3.40, p = 0.05). Conversely, Negative interactions were found between high plant-source nitrate/nitrite intake with high KYN and TMAO levels on MetS and some components.

Conclusion

There is an interaction between dietary nitrate/nitrite source (animal vs. plant) and gut microbial metabolites (TMAO and KYN) on the risk of of MetS and its components. These findings highlight the importance of considering diet, gut microbiome metabolites, and their interactions in MetS risk assessment.

Changes in nitric oxide inhibitors and mortality in critically ill patients: a cohort study

BACKGROUND

Optimal balance between macro- and microcirculation in critically ill patients is crucial for ensuring optimal organ perfusion. Nitric oxide (NO) is a regulator of vascular hemostasis and tone. The availability of NO is controlled by asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and the availability of the NO substrates arginine and homoarginine. We investigated the changes in plasma concentrations of ADMA, SDMA, arginine, and homoarginine days 1-5 of intensive care unit (ICU) admission and the association between the change in concentration days 1-3 and 30-day all-cause mortality.

METHODS

Single-center cohort study of adult critically ill patients from the ICU at Copenhagen University Hospital - North Zealand. ADMA, SDMA, arginine, and homoarginine (NO-biomarkers) were measured on days 1-5. Initially, we determined the changes in NO-biomarkers days 1-5 with linear mixed models, and subsequently how the changes in NO-biomarkers days 1-3 were associated with 30-day all-cause mortality. Post-hoc we analyzed the association between plasma concentration at admission and 30-day all-cause mortality.

RESULTS

In total 567 out of 577 patients had plasma samples from days 1-5. Plasma concentrations of ADMA and arginine increased from days 1-5. SDMA concentrations increased from days 1-2, followed by a decrease from days 2-5. Concentrations of homoarginine did not change from days 1-3 but slightly increased from days 3-5. In total 512 patients were alive 3 days after ICU admission. Among these patients, a daily twofold increase in ADMA concentration from days 1-3 was associated with decreased mortality in multivariate analysis (HR 0.45; 95% CI 0.21-0.98; p = 0.046). An increase in SDMA, arginine, or homoarginine was not associated with mortality. Post-hoc we found that a twofold increase in ADMA or SDMA concentrations at admission was associated with mortality (HR 1.78; 95% CI 1.24-2.57; p = 0.0025, and HR 1.41; 95% CI 1.05-1.90; p = 0.024, respectively).

CONCLUSIONS

Increasing ADMA concentrations on days 1-3 are inversely associated with mortality, however not with the same strength as high ADMA or SDMA concentrations at admission. We suggest that admission concentrations are the focus of future research on ADMA and SDMA as predictors of mortality or potential therapeutical targets in ICU patients.

Pulmonary Vascular Dysfunctions in Cystic Fibrosis

Cystic fibrosis (CF) is an inherited disorder caused by a deleterious mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Given that the CFTR protein is a chloride channel expressed on a variety of cells throughout the human body, mutations in this gene impact several organs, particularly the lungs. For this very reason, research regarding CF disease and CFTR function has historically focused on the lung airway epithelium. Nevertheless, it was discovered more than two decades ago that CFTR is also expressed and functional on endothelial cells. Despite the great strides that have been made in understanding the role of CFTR in the airway epithelium, the role of CFTR in the endothelium remains unclear. Considering that the airway epithelium and endothelium work in tandem to allow gas exchange, it becomes very crucial to understand how a defective CFTR protein can impact the pulmonary vasculature and overall lung function. Fortunately, more recent research has been dedicated to elucidating the role of CFTR in the endothelium. As a result, several vascular dysfunctions associated with CF disease have come to light. Here, we summarize the current knowledge on pulmonary vascular dysfunctions in CF and discuss applicable therapies.

Cardioprotection by Poloxamer 188 is Mediated through Increased Endothelial Nitric Oxide Production

Ischemia/reperfusion (I/R) injury significantly contributes to the morbidity and mortality associated with cardiac events. Poloxamer 188 (P188), a nonionic triblock copolymer, has been proposed to mitigate I/R injury by stabilizing cell membranes. However, the underlying mechanisms remain incompletely understood, particularly concerning endothelial cell function and nitric oxide (NO) production. We employed human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs) and endothelial cells (ECs) to elucidate the effects of P188 on cellular survival, function, and NO secretion under simulated I/R conditions. iPSC-CMs contractility and iPSC-ECs' NO production were assessed following exposure to P188. Further, an isolated heart model using Brown Norway rats subjected to I/R injury was utilized to evaluate the ex-vivo cardioprotective effects of P188, examining cardiac function and NO production, with and without the administration of a NO inhibitor. In iPSC-derived models, P188 significantly preserved CM contractile function and enhanced cell viability after hypoxia/reoxygenation. Remarkably, P188 treatment led to a pronounced increase in NO secretion in iPSC-ECs, a novel finding demonstrating endothelial protective effects beyond membrane stabilization. In the rat isolated heart model, administration of P188 during reperfusion notably improved cardiac function and reduced I/R injury markers. This cardioprotective effect was abrogated by NO inhibition, underscoring the pivotal role of NO. Additionally, a dose-dependent increase in NO production was observed in non-ischemic rat hearts treated with P188, further establishing the critical function of NO in P188 induced cardioprotection. In conclusion, our comprehensive study unveils a novel role of NO in mediating the protective effects of P188 against I/R injury. This mechanism is evident in both cellular models and intact rat hearts, highlighting the potential of P188 as a therapeutic agent against I/R injury. Our findings pave the way for further investigation into P188's therapeutic mechanisms and its potential application in clinical settings to mitigate I/R-related cardiac dysfunction.

Retention of Improved Plantar Sensation in Patients with Type II Diabetes Mellitus and Sensory Peripheral Neuropathy after One Month of Vibrating Insole Therapy: A Pilot Study

Sensory peripheral neuropathy is a common complication of diabetes mellitus and the biggest risk factor for diabetic foot ulcers. There is currently no available treatment that can reverse sensory loss in the diabetic population. The application of mechanical noise has been shown to improve vibration perception threshold or plantar sensation (through stochastic resonance) in the short term, but the therapeutic use, and longer-term effects have not been explored. In this study, vibrating insoles were therapeutically used by 22 participants, for 30 min per day, on a daily basis, for a month by persons with diabetic sensory peripheral neuropathy. The therapeutic application of vibrating insoles in this cohort significantly improved VPT by an average of 8.5 V (p = 0.001) post-intervention and 8.2 V (p < 0.001) post-washout. This statistically and clinically relevant improvement can play a role in protection against diabetic foot ulcers and the delay of subsequent lower-extremity amputation.

Disturbed fluid flow reinforces endothelial tractions and intercellular stresses

Disturbed fluid flow is well understood to have significant ramifications on endothelial function, but the impact disturbed flow has on endothelial biomechanics is not well understood. In this study, we measured tractions, intercellular stresses, and cell velocity of endothelial cells exposed to disturbed flow using a custom-fabricated flow chamber. Our flow chamber exposed cells to disturbed fluid flow within the following spatial zones: zone 1 (inlet; length 0.676-2.027 cm): 0.0037 ± 0.0001 Pa; zone 2 (middle; length 2.027-3.716 cm): 0.0059 ± 0.0005 Pa; and zone 3 (outlet; length 3.716-5.405 cm): 0.0051 ± 0.0025 Pa. Tractions and intercellular stresses were observed to be highest in the middle of the chamber (zone 2) and lowest at the chamber outlet (zone 3), while cell velocity was highest near the chamber inlet (zone 1), and lowest near the middle of the chamber (zone 2). Our findings suggest endothelial biomechanical response to disturbed fluid flow to be dependent on not only shear stress magnitude, but the spatial shear stress gradient as well. We believe our results will be useful to a host of fields including endothelial cell biology, the cardiovascular field, and cellular biomechanics in general.

Chemokine Fractalkine and Non-Obstructive Coronary Artery Disease-Is There a Link?

Non-obstructive coronary artery disease (NO-CAD) constitutes a heterogeneous group of conditions collectively characterized by less than 50% narrowing in at least one major coronary artery with a fractional flow reserve (FFR) of ≤0.80 observed in coronary angiography. The pathogenesis and progression of NO-CAD are still not fully understood, however, inflammatory processes, particularly atherosclerosis and microvascular dysfunction are known to play a major role in it. Chemokine fractalkine (FKN/CX3CL1) is inherently linked to these processes. FKN/CX3CL1 functions predominantly as a chemoattractant for immune cells, facilitating their transmigration through the vessel wall and inhibiting their apoptosis. Its concentrations correlate positively with major cardiovascular risk factors. Moreover, promising preliminary results have shown that FKN/CX3CL1 receptor inhibitor (KAND567) administered in the population of patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI), inhibits the adverse reaction of the immune system that causes hyperinflammation. Whereas the link between FKN/CX3CL1 and NO-CAD appears evident, further studies are necessary to unveil this complex relationship. In this review, we critically overview the current data on FKN/CX3CL1 in the context of NO-CAD and present the novel clinical implications of the unique structure and function of FKN/CX3CL1 as a compound which distinctively contributes to the pathomechanism of this condition.

Nitric oxide as a double-edged sword in pulmonary viral infections: Mechanistic insights and potential therapeutic implications

In the face of the global pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), researchers are tirelessly exploring novel therapeutic approaches to combat coronavirus disease 2019 (COVID-19) and its associated complications. Nitric oxide (NO) has appeared as a multifaceted signaling mediator with diverse and often contrasting biological activities. Its intricate biochemistry renders it a crucial regulator of cardiovascular and pulmonary functions, immunity, and neurotransmission. Perturbations in NO production, whether excessive or insufficient, contribute to the pathogenesis of various diseases, encompassing cardiovascular disease, pulmonary hypertension, asthma, diabetes, and cancer. Recent investigations have unveiled the potential of NO donors to impede SARS-CoV- 2 replication, while inhaled NO demonstrates promise as a therapeutic avenue for improving oxygenation in COVID-19-related hypoxic pulmonary conditions. Interestingly, NO's association with the inflammatory response in asthma suggests a potential protective role against SARS-CoV-2 infection. Furthermore, compelling evidence indicates the benefits of inhaled NO in optimizing ventilation-perfusion ratios and mitigating the need for mechanical ventilation in COVID-19 patients. In this review, we delve into the molecular targets of NO, its utility as a diagnostic marker, the mechanisms underlying its action in COVID-19, and the potential of inhaled NO as a therapeutic intervention against viral infections. The topmost significant pathway, gene ontology (GO)-biological process (BP), GO-molecular function (MF) and GO-cellular compartment (CC) terms associated with Nitric Oxide Synthase (NOS)1, NOS2, NOS3 were arginine biosynthesis (p-value = 1.15 x 10-9) regulation of guanylate cyclase activity (p-value = 7.5 x 10-12), arginine binding (p-value = 2.62 x 10-11), vesicle membrane (p-value = 3.93 x 10-8). Transcriptomics analysis further validates the significant presence of NOS1, NOS2, NOS3 in independent COVID-19 and pulmonary hypertension cohorts with respect to controls. This review investigates NO's molecular targets, diagnostic potentials, and therapeutic role in COVID-19, employing bioinformatics to identify key pathways and NOS isoforms' significance.

Early and late-onset preeclampsia: effects of DDAH2 polymorphisms on ADMA levels and association with DDAH2 haplotypes

Objective

To examine whether the DDAH2 promoter polymorphisms -1415G/A (rs2272592), -1151A/C (rs805304) and -449G/C (rs805305), and their haplotypes, are associated with PE compared with normotensive pregnant women, and whether they affect ADMA levels in these groups.

Methods

A total of 208 pregnant women were included in the study and classified as early-onset (N=57) or late-onset PE (N =49), and as normotensive pregnant women (N = 102).

Results

Pregnant with early-onset PE carrying the GC and GG genotypes for the DDAH2 -449G/C polymorphism had increased ADMA levels (P=0.01). No association of DDAH2 polymorphisms with PE in single-locus analysis was found. However, the G-C-G haplotype was associated with the risk for late-onset PE.

Conclusion

It is suggested that DDAH2 polymorphisms could affect ADMA levels in PE, and that DDAH2 haplotypes may affect the risk for PE.

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

Adrenoceptors in the Eye - Physiological and Pathophysiological Relevance

The autonomic nervous system plays a crucial role in the innervation of the eye. Consequently, it comes as no surprise that catecholamines and their corresponding receptors have been extensively studied and characterized in numerous ocular structures, including the cornea, conjunctiva, lacrimal gland, trabecular meshwork, uvea, and retina. These investigations have unveiled substantial clinical implications, particularly in the context of treating glaucoma, a progressive neurodegenerative disorder responsible for irreversible vision loss on a global scale. The primary therapeutic approaches for glaucoma frequently involve the modulation of α1-, α2-, and β-adrenoceptors, making them pivotal targets. In this chapter, we offer a comprehensive overview of the expression, distribution, and functional roles of adrenoceptors within various components of the eye and its associated structures. Additionally, we delve into the pivotal role of adrenoceptors in the pathophysiology of glaucoma. Furthermore, we provide a concise historical perspective on adrenoceptor research, examine the distinct contributions of individual adrenoceptor subtypes to the treatment of various ocular conditions, and propose potential future avenues of exploration in this field.

β-Arrestin pathway activation by selective ATR1 agonism promotes calcium influx in podocytes, leading to glomerular damage

Angiotensin receptor blockers (ARBs) are the first-line treatment for hypertension; they act by inhibiting signaling through the angiotensin 1 receptor (AT1R). Recently, a novel biased AT1R agonist, TRV120027 (TRV), which selectively activates the β-arrestin cascade and blocks the G-protein-coupled receptor pathway has been proposed as a potential blood pressure medication. Here, we explored the effects of TRV and associated β-arrestin signaling in podocytes, essential cells of the kidney filter. We used human podocyte cell lines to determine β-arrestin's involvement in calcium signaling and cytoskeletal reorganization and Dahl SS rats to investigate the chronic effects of TRV administration on glomerular health. Our experiments indicate that the TRV-activated β-arrestin pathway promotes the rapid elevation of intracellular Ca2+ in a dose-dependent manner. Interestingly, the amplitude of β-arrestin-mediated Ca2+ influx was significantly higher than the response to similar Ang II concentrations. Single-channel analyses show rapid activation of transient receptor potential canonical (TRPC) channels following acute TRV application. Furthermore, the pharmacological blockade of TRPC6 significantly attenuated the β-arrestin-mediated Ca2+ influx. Additionally, prolonged activation of the β-arrestin pathway in podocytes resulted in pathological actin cytoskeleton rearrangements, higher apoptotic cell markers, and augmented glomerular damage. TRV-activated β-arrestin signaling in podocytes may promote TRPC6 channel-mediated Ca2+ influx, foot process effacement, and apoptosis, possibly leading to severe defects in glomerular filtration barrier integrity and kidney health. Under these circumstances, the potential therapeutic application of TRV for hypertension treatment requires further investigation to assess the balance of the benefits versus possible deleterious effects and off-target damage.

Medical Management and Device-Based Therapies in Chronic Heart Failure

Heart failure (HF) remains a major cause of morbidity and mortality worldwide. Major advancements in optimal guideline-directed medical therapy, including novel pharmacological agents, are now available for the treatment of chronic HF including HF with reduced ejection fraction and HF with preserved ejection fraction. Despite these efforts, there are several limitations of medical therapy including but not limited to: delays in implementation and/or initiation; inability to achieve target dosing; tolerability; adherence; and recurrent and chronic costs of care. A significant proportion of patients remain symptomatic with poor HF-related outcomes including rehospitalization, progression of disease, and mortality. Driven by these unmet clinical needs, there has been a significant growth of innovative device-based interventions across all HF phenotypes over the past several decades. This state-of-the-art review will summarize the current landscape of guideline-directed medical therapy for chronic HF, discuss its limitations including barriers to implementation, and review device-based therapies which have established efficacy or demonstrated promise in the management of chronic HF.

Endothelial cell dysfunction in cardiac disease: driver or consequence?

The vascular endothelium is a multifunctional cellular system which directly influences blood components and cells within the vessel wall in a given tissue. Importantly, this cellular interface undergoes critical phenotypic changes in response to various biochemical and hemodynamic stimuli, driving several developmental and pathophysiological processes. Multiple studies have indicated a central role of the endothelium in the initiation, progression, and clinical outcomes of cardiac disease. In this review we synthesize the current understanding of endothelial function and dysfunction as mediators of the cardiomyocyte phenotype in the setting of distinct cardiac pathologies; outline existing in vivo and in vitro models where key features of endothelial cell dysfunction can be recapitulated; and discuss future directions for development of endothelium-targeted therapeutics for cardiac diseases with limited existing treatment options.

Phase-transited lysozyme nanofilm with co-immobilized copper ion and heparin as cardiovascular stent multifunctional coating

Cardiovascular metal stents have shown potential in the treatment of coronary artery disease using percutaneous coronary intervention. However, thrombosis, endothelialization, and new atherosclerosis after stent implantation remain unsolved problems. Herein, a multifunctional coating material based on phase-transited lysozyme was developed to promote stent endothelialization and simultaneously reduce thrombus events by embedding moieties of heparin and co-immobilized copper ions for in-situ catalyzing nitric oxide (NO) generation. The lysozyme-based biomimetic coating is compatible with blood and enables facile loading and sustainable release of copper ions to produce NO with donors via catalytic reaction. The novel coating strategy displayed several bio-effects of anti-thrombosis; it synergistically promoted endothelial cell growth and inhibited smooth muscle cell growth. Thus, this systemic in vitro study will provide a foundation for developing multifunctional cardiovascular stents in clinical settings.

Effects of Nitric Oxide on the Activity of P2X and TRPV1 Receptors in Rat Meningeal Afferents of the Trigeminal Nerve

Nitric oxide is one of the endogenous molecules that play a key role in migraine. However, the interaction between NO and the main players in the nociceptive activity of the meningeal trigeminal afferents-TRPV1 and P2X3 receptors-remains unstudied. In the current project, the effects of acute and chronic NO administration on the activity of TRPV1 and P2X3 receptors in the peripheral afferents were studied using electrophysiological recording of action potentials of the trigeminal nerve in the rat hemiskull preparations. The data obtained indicate that exogenous and endogenous NO increased the activity of the trigeminal nerve independent on the inhibition of the TRPV1 and P2X3 receptors. The activity of the trigeminal nerve triggered by ATP changed neither in acute incubation in the NO donor-sodium nitroprusside (SNP) nor in the chronic nitroglycerine (NG)-induced migraine model. Moreover, the chronic NG administration did not increase in the number of degranulated mast cells in the rat meninges. At the same time, the capsaicin-induced activity of the trigeminal nerve was higher with chronic NO administration or after acute NO application, and these effects were prevented by N-ethylmaleimide. In conclusion, we suggested that NO positively modulates the activity of TRPV1 receptors by S-nitrosylation, which may contribute to the pro-nociceptive action of NO and underlie the sensitization of meningeal afferents in chronic migraine.

Targeting VCAM-1: a therapeutic opportunity for vascular damage

INTRODUCTION

The vascular cell adhesion molecule (VCAM-1) is a transmembrane sialoglycoprotein detected in activated endothelial and vascular smooth muscle cells involved in the adhesion and transmigration of inflammatory cells into damaged tissue. Widely used as a pro-inflammatory marker, its potential role as a targeting molecule has not been thoroughly explored.

AREAS COVERED

We discuss the current evidence supporting the potential targeting of VCAM-1 in atherosclerosis, diabetes, hypertension and ischemia/reperfusion injury.

EXPERT OPINION

There is emerging evidence that VCAM-1 is more than a biomarker and may be a promising therapeutic target for vascular diseases. While there are neutralizing antibodies that allow preclinical research, the development of pharmacological tools to activate or inhibit this protein are required to thoroughly assess its therapeutic potential.

Endothelial dysfunction: developmental mechanisms and therapeutic strategies

Introduction: Every year the importance of the normal functioning of the endothelial layer of the vascular wall in maintaining the health of the body becomes more and more obvious.

The physiological role of the endothelium: The endothelium is a metabolically active organ actively involved in the regulation of hemostasis, modulation of inflammation, maintenance of hemovascular homeostasis, regulation of angiogenesis, vascular tone, and permeability.

Risk factors for the development of endothelial dysfunction: Currently, insufficient bioavailability of nitric oxide is considered the most significant risk factor for endothelial dysfunction.

Mechanisms of development of endothelial dysfunction: The genesis of endothelial dysfunction is a multifactorial process. Among various complex mechanisms, this review examines oxidative stress, inflammation, hyperglycemia, vitamin D deficiency, dyslipidemia, excess visceral fat, hyperhomocysteinemia, hyperuricemia, as well as primary genetic defect of endotheliocytes, as the most common causes in the population underlying the development of endothelial dysfunction.

Markers of endothelial dysfunction in various diseases: This article discusses the main biomarkers of endothelial dysfunction currently used, as well as promising biomarkers in the future for laboratory diagnosis of this pathology.

Therapeutic strategies: Therapeutic approaches to the endothelium in order to prevent or reduce a degree of damage to the vascular wall are briefly described.

Conclusion: Endothelial dysfunction is a typical pathological process involved in the pathogenesis of many diseases. Thus, pharmacological agents with endothelioprotective properties can provide more therapeutic benefits than a drug without such an effect.

Wild Watermelon-Extracted Juice Ingestion Reduces Peripheral Arterial Stiffness with an Increase in Nitric Oxide Production: A Randomized Crossover Pilot Study

Wild watermelon contains various nutrients, but the effect of its acute ingestion on arterial stiffness is unclear. This study aimed to investigate whether a single bout of acute ingestion of wild watermelon-extracted juice decreased arterial stiffness concomitant with an increase in nitric oxide (NO) production. Twelve healthy young female participants were tested under two conditions in a randomized, double-blind crossover study: (1) a beverage containing 90 g of wild watermelon extract and (2) a control beverage: a placebo. Pulse wave velocity (PWV), an index of arterial stiffness, blood flow, and plasma nitrate/nitrite (NOx) levels were measured in the supine position at 30, 60, and 90 min after the intake of each beverage. The changes in femoral-ankle PWV were significantly reduced after wild watermelon-extracted juice intake compared to those in the placebo group. Additionally, the changes in blood flow in the posterior tibial artery and plasma NOx levels after intake of wild watermelon-extracted juice were significantly increased compared to those in the placebo group. These data show that acute ingestion of wild watermelon-extracted juice reduces peripheral (lower limb) arterial stiffness and increases NO bioavailability. To confirm these associations, more detailed investigations of the nutrients that influence these effects should be conducted.

Hyperoxaluria Induces Endothelial Dysfunction in Preglomerular Arteries: Involvement of Oxidative Stress

Urolithiasis is a worldwide problem and a risk factor for kidney injury. Oxidative stress-associated renal endothelial dysfunction secondary to urolithiasis could be a key pathogenic factor, similar to obesity and diabetes-related nephropathy. The aim of the present study was to characterize urolithiasis-related endothelial dysfunction in a hyperoxaluria rat model of renal lithiasis. Experimental approach: Endothelial dysfunction was assessed in preglomerular arteries isolated from control rats and in which 0.75% ethylene glycol was administered in drinking water. Renal interlobar arteries were mounted in microvascular myographs for functional studies; superoxide generation was measured by chemiluminescence and mRNA and protein expression by RT-PCR and immunofluorescence, respectively. Selective inhibitors were used to study the influence of the different ROS sources, xanthine oxidase, COX-2, Nox1, Nox2 and Nox4. Inflammatory vascular response was also studied by measuring the RNAm expression of NF-κB, MCP-1 and TNFα by RT-PCR. Results: Endothelium-dependent vasodilator responses were impaired in the preglomerular arteries of the hyperoxaluric group along with higher superoxide generation in the renal cortex and vascular inflammation developed by MCP-1 and promoted by NF-κB. The xanthine oxidase inhibitor allopurinol restored the endothelial relaxations and returned superoxide generation to basal values. Nox1 and Nox2 mRNA were up-regulated in arteries from the hyperoxaluric group, and Nox1 and Nox2 selective inhibitors also restored the impaired vasodilator responses and normalized NADPH oxidase-dependent higher superoxide values of renal cortex from the hyperoxaluric group. Conclusions: The current data support that hyperoxaluria induces oxidative stress-mediated endothelial dysfunction and inflammatory response in renal preglomerular arteries which is promoted by the xanthine oxidase, Nox1 and Nox2 pathways.

2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure" replaces the "2013 ACCF/AHA Guideline for the Management of Heart Failure" and the "2017 ACC/AHA/HFSA Focused Update of the 2013 ACCF/AHA Guideline for the Management of Heart Failure." The 2022 guideline is intended to provide patient-centric recommendations for clinicians to prevent, diagnose, and manage patients with heart failure.

METHODS

A comprehensive literature search was conducted from May 2020 to December 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from MEDLINE (PubMed), EMBASE, the Cochrane Collaboration, the Agency for Healthcare Research and Quality, and other relevant databases. Additional relevant clinical trials and research studies, published through September 2021, were also considered. This guideline was harmonized with other American Heart Association/American College of Cardiology guidelines published through December 2021. Structure: Heart failure remains a leading cause of morbidity and mortality globally. The 2022 heart failure guideline provides recommendations based on contemporary evidence for the treatment of these patients. The recommendations present an evidence-based approach to managing patients with heart failure, with the intent to improve quality of care and align with patients' interests. Many recommendations from the earlier heart failure guidelines have been updated with new evidence, and new recommendations have been created when supported by published data. Value statements are provided for certain treatments with high-quality published economic analyses.

2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure

AIM

The "2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure" replaces the "2013 ACCF/AHA Guideline for the Management of Heart Failure" and the "2017 ACC/AHA/HFSA Focused Update of the 2013 ACCF/AHA Guideline for the Management of Heart Failure." The 2022 guideline is intended to provide patient-centric recommendations for clinicians to prevent, diagnose, and manage patients with heart failure.

METHODS

A comprehensive literature search was conducted from May 2020 to December 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from MEDLINE (PubMed), EMBASE, the Cochrane Collaboration, the Agency for Healthcare Research and Quality, and other relevant databases. Additional relevant clinical trials and research studies, published through September 2021, were also considered. This guideline was harmonized with other American Heart Association/American College of Cardiology guidelines published through December 2021.

STRUCTURE

Heart failure remains a leading cause of morbidity and mortality globally. The 2022 heart failure guideline provides recommendations based on contemporary evidence for the treatment of these patients. The recommendations present an evidence-based approach to managing patients with heart failure, with the intent to improve quality of care and align with patients' interests. Many recommendations from the earlier heart failure guidelines have been updated with new evidence, and new recommendations have been created when supported by published data. Value statements are provided for certain treatments with high-quality published economic analyses.

Arenaviral infection causes bleeding in mice due to reduced serotonin release from platelets

Bleeding correlates with disease severity in viral hemorrhagic fevers. We found that the increase in type I interferon (IFN-I) in mice caused by infection with the Armstrong strain of lymphocytic choriomeningitis virus (LCMV; an arenavirus) reduced the megakaryocytic expression of genes encoding enzymes involved in lipid biosynthesis (cyclooxygenase 1 and thromboxane A synthase 1) and a thrombopoietic transcription factor (Nf-e2). The decreased expression of these genes was associated with reduced numbers of circulating platelets and defects in the arachidonic acid synthetic pathway, thereby suppressing serotonin release from δ-granules in platelets. Bleeding resulted when severe thrombocytopenia and altered platelet function reduced the amount of platelet-derived serotonin below a critical threshold. Bleeding was facilitated by the absence of the activity of the kinase Lyn or the administration of aspirin, an inhibitor of arachidonic acid synthesis. Mouse platelets were not directly affected by IFN-I because they lack the receptor for the cytokine (IFNAR1), suggesting that transfusion of normal platelets into LCMV-infected mice could increase the amount of platelet-released serotonin and help to control hemorrhage.

Endothelial regulation of calmodulin expression and eNOS-calmodulin interaction in vascular smooth muscle

Calmodulin (CaM) is a Ca²⁺ sensor protein that is required for numerous vascular smooth muscle cell (VSMC) functions. Since CaM is not expressed enough for its many target proteins, factors that modulate its expression and interactions with targets in VSMCs can have extensive effects on vascular functions. VSMCs receive many regulatory inputs from endothelial cells (ECs). However, it is unknown if ECs regulate vascular functions via controlling expression of CaM and its interactions in VSMCs. In this work, we tested the hypothesis that ECs also affect VSMC signaling via regulation of CaM expression and interactions with its target proteins in VSMCs. Using ECs and VSMCs isolated from the same vessels and grown in a co-culture system, we observed that the presence of proliferating ECs significantly upregulates total CaM expression in VSMCs. An imaging module was devised to concurrently measure free Ca²⁺ and CaM levels in VSMCs in co-culture with ECs. Using indo-1/AM and a CaM biosensor built from a modified CaM-binding sequence of endothelial nitric oxide synthase (eNOS), this system revealed that in response to a generic Ca²⁺ signal, free Ca²⁺-bound CaM level is enhanced ~ threefold in VSMCs in co-culture with proliferating ECs. Interestingly, VSMCs express eNOS and eNOS-CaM association in response to the same Ca²⁺ stimulus is also enhanced ~ threefold in VSMCs co-cultured with ECs. Mechanistically, the endothelium-dependent upregulation of CaM in VSMCs is not affected by inhibition of NO production or endothelin receptors but is prevented by inhibition of vascular endothelial growth factor receptors. Consistently, VEGF-A level is upregulated in VSMCs co-cultured with proliferating ECs. These data indicate a new role of the endothelium in regulating vascular functions via upregulating CaM and its interactions in VSMCs.

Involvement of Fatty Acids and Their Metabolites in the Development of Inflammation in Atherosclerosis

Despite all the advances of modern medicine, atherosclerosis continues to be one of the most important medical and social problems. Atherosclerosis is the cause of several cardiovascular diseases, which are associated with high rates of disability and mortality. The development of atherosclerosis is associated with the accumulation of lipids in the arterial intima and the disruption of mechanisms that maintain the balance between the development and resolution of inflammation. Fatty acids are involved in many mechanisms of inflammation development and maintenance. Endothelial cells demonstrate multiple cross-linkages between lipid metabolism and innate immunity. In addition, these processes are linked to hemodynamics and the function of other cells in the vascular wall, highlighting the central role of the endothelium in vascular biology.

Impairment of Anti-Aggregatory Responses to Nitric Oxide and Prostacyclin: Mechanisms and Clinical Implications in Cardiovascular Disease

The propensity towards platelet-rich thrombus formation increases substantially during normal ageing, and this trend is mediated by decreases in platelet responsiveness to the anti-aggregatory nitric oxide (NO) and prostacyclin (PGI2) pathways. The impairment of soluble guanylate cyclase and adenylate cyclase-based signalling that is associated with oxidative stress represents the major mechanism of this loss of anti-aggregatory reactivity. Platelet desensitization to these autacoids represents an adverse prognostic marker in patients with ischemic heart disease and may contribute to increased thrombo-embolic risk in patients with heart failure. Patients with platelet resistance to PGI2 also are unresponsive to ADP receptor antagonist therapy. Apart from ischemia, diabetes and aortic valve disease are also associated with impaired anti-aggregatory homeostasis. This review examines the association of impaired platelet cyclic nucleotide (i.e., cGMP and cAMP) signalling with the emerging evidence of thromboembolic risk in cardiovascular diseases, and discusses the potential therapeutic strategies targeting this abnormality.

High Soluble Endoglin Levels Affect Aortic Vascular Function during Mice Aging

Endoglin is a 180 kDa transmembrane glycoprotein that was demonstrated to be present in two different endoglin forms, namely membrane endoglin (Eng) and soluble endoglin (sEng). Increased sEng levels in the circulation have been detected in atherosclerosis, arterial hypertension, and type II diabetes mellitus. Moreover, sEng was shown to aggravate endothelial dysfunction when combined with a high-fat diet, suggesting it might be a risk factor for the development of endothelial dysfunction in combination with other risk factors. Therefore, this study hypothesized that high sEng levels exposure for 12 months combined with aging (an essential risk factor of atherosclerosis development) would aggravate vascular function in mouse aorta. Male transgenic mice with high levels of human sEng in plasma (Sol-Eng⁺) and their age-matched male transgenic littermates that do not develop high soluble endoglin (Control) on a chow diet were used. The aging process was initiated to contribute to endothelial dysfunction/atherosclerosis development, and it lasted 12 months. Wire myograph analysis showed impairment contractility in the Sol-Eng⁺ group when compared to the control group after KCl and PGF_2α administration. Endothelium-dependent responsiveness to Ach was not significantly different between these groups. Western blot analysis revealed significantly decreased protein expression of Eng, p-eNOS, and ID1 expression in the Sol-Eng⁺ group compared to the control group suggesting reduced Eng signaling. In conclusion, we demonstrated for the first time that long-term exposure to high levels of sEng during aging results in alteration of vasoconstriction properties of the aorta, reduced eNOS phosphorylation, decreased Eng expression, and altered Eng signaling. These findings suggest that sEng can be considered a risk factor for the development of vascular dysfunction during aging and a potential therapeutical target for pharmacological intervention.

Vasoprotective Actions of Nitroxyl (HNO): A Story of Sibling Rivalry

ABSTRACT

Nitroxyl (HNO), the 1 electron-reduced and protonated form of nitric oxide (NO•), has emerged as a nitrogen oxide with a suite of vasoprotective properties and therapeutic advantages over its redox sibling. Although HNO has garnered much attention due to its cardioprotective actions in heart failure, its ability to modulate vascular function, without the limitations of tolerance development and NO• resistance, is desirable in the treatment of vascular disease. HNO serves as a potent vasodilator and antiaggregatory agent and has an ability to limit vascular inflammation and reactive oxygen species generation. In addition, its resistance to scavenging by reactive oxygen species and ability to target distinct vascular signaling pathways (Kv, KATP, and calcitonin gene-related peptide) contribute to its preserved efficacy in hypertension, diabetes, and hypercholesterolemia. In this review, the vasoprotective actions of HNO will be compared with those of NO•, and the therapeutic utility of HNO donors in the treatment of angina, acute cardiovascular emergencies, and chronic vascular disease are discussed.

Anti-Apoptotic Effect of Flavokawain A on Ochratoxin-A-Induced Endothelial Cell Injury by Attenuation of Oxidative Stress via PI3K/AKT-Mediated Nrf2 Signaling Cascade

This study investigates the endothelial protective activity of flavokawain A (FKA) against oxidative stress induced by ochratoxin A (OTA), which acts as a mycotoxin, and its primary mechanisms in in vitro models. Reactive oxygen species, in general, regulate oxidative stress that significantly contributes to the pathophysiology of endothelial dysfunctions. OTA exerts toxicity through inflammation and the accumulation of ROS. This research is aimed at exploring the defensive function of FKA against the endothelial injury triggered by OTA through the Nrf2 pathway regulated by PI3K/AKT. OTA exposure significantly increased the nuclear translocation of NFκB, whereas we found a reduction in inflammation via NFκB inhibition with FKA treatment. FKA increased the PI3K and AKT phosphorylation, which may lead to the stimulation of antioxidative and antiapoptotic signaling in HUVECs. It also upregulated the phosphorylation of Nrf2 and a concomitant expression of antioxidant genes, such as HO-1, NQO-1, and γGCLC, depending on the dose under the oxidative stress triggered by OTA. Knockdown of Nrf2 through small interfering RNA (siRNA) impedes the protective role of FKA against the endothelial toxicity induced by OTA. In addition, FKA enhanced Bcl2 activation while suppressing apoptosis marker proteins. Therefore, FKA is regarded as a potential agent against endothelial oxidative stress caused by the deterioration of the endothelium. The research findings showed that FKA plays a key role in activating the p-PI3K/p-AKT and Nrf2 signaling pathways, while suppressing caspase-dependent apoptosis.

Modulation of endothelium function by fatty acids

The endothelium acts as the barrier that prevents circulating lipids such as lipoproteins and fatty acids into the arterial wall; it also regulates normal functioning in the circulatory system by balancing vasodilation and vasoconstriction, modulating the several responses and signals. Plasma lipids can interact with endothelium via different mechanisms and produce different phenotypes. Increased plasma-free fatty acids (FFAs) levels are associated with the pathogenesis of atherosclerosis and cardiovascular diseases (CVD). Because of the multi-dimensional roles of plasma FFAs in mediating endothelial dysfunction, increased FFA level is now considered an essential link in the onset of endothelial dysfunction in CVD. FFA-mediated endothelial dysfunction involves several mechanisms, including dysregulated production of nitric oxide and cytokines, metaflammation, oxidative stress, inflammation, activation of the renin-angiotensin system, and apoptosis. Therefore, modulation of FFA-mediated pathways involved in endothelial dysfunction may prevent the complications associated with CVD risk. This review presents details as to how endothelium is affected by FFAs involving several metabolic pathways.

Synaptic dysregulation and hyperexcitability induced by intracellular amyloid beta oligomers

Intracellular amyloid beta oligomer (iAβo) accumulation and neuronal hyperexcitability are two crucial events at early stages of Alzheimer's disease (AD). However, to date, no mechanism linking iAβo with an increase in neuronal excitability has been reported. Here, the effects of human AD brain-derived (h-iAβo) and synthetic (iAβo) peptides on synaptic currents and action potential firing were investigated in hippocampal neurons. Starting from 500 pM, iAβo rapidly increased the frequency of synaptic currents and higher concentrations potentiated the AMPA receptor-mediated current. Both effects were PKC-dependent. Parallel recordings of synaptic currents and nitric oxide (NO)-associated fluorescence showed that the increased frequency, related to pre-synaptic release, was dependent on a NO-mediated retrograde signaling. Moreover, increased synchronization in NO production was also observed in neurons neighboring those dialyzed with iAβo, indicating that iAβo can increase network excitability at a distance. Current-clamp recordings suggested that iAβo increased neuronal excitability via AMPA-driven synaptic activity without altering membrane intrinsic properties. These results strongly indicate that iAβo causes functional spreading of hyperexcitability through a synaptic-driven mechanism and offers an important neuropathological significance to intracellular species in the initial stages of AD, which include brain hyperexcitability and seizures.

Characterization of endothelium-dependent and -independent processes in occipital artery of the rat: Relevance to control of blood flow to nodose sensory cells

Circulating factors access cell bodies of vagal afferents in nodose ganglia (NG) via the occipital artery (OA). Constrictor responses of OA segments closer in origin from the external carotid artery (ECA) differ from segments closer to NG. Our objective was to determine the role of endothelium in this differential vasoreactivity in rat OA segments. Vasoreactivity of OA segments (proximal segments closer to ECA, distal segments closer to NG) were examined in wire myographs. We evaluated (a) vasoconstrictor effects of 5-hydroxytryptamine (5-HT) in intact and endothelium-denuded OA segments in absence/presence of soluble guanylate cyclase (SGC) inhibitor ODQ, (b) vasodilator responses elicited by NO-donor MAHMA NONOate in intact or endothelium-denuded OA segments in absence/presence of ODQ, and (c) vasodilator responses elicited by endothelium-dependent vasodilator, acetylcholine (ACh), in intact OA segments in absence/presence of ODQ. Intact distal OA responded more to 5-HT than intact proximal OA. Endothelium denudation increased 5-HT potency in both OA segments, especially proximal OA. ODQ increased maximal responses of 5HT in both segments, particularly proximal OA. ACh similarly relaxed both OA segments, effects abolished by endothelial denudation and attenuated by ODQ. MAHMA NONOate elicited transient vasodilation in both segments. Effects of ODQ against ACh were segment-dependent whereas those against MAHMA NONOate were not. The endothelium regulates OA responsiveness in a segment-dependently fashion. Endothelial cells at the OA-ECA junction more strongly influence vascular tone than those closer to NG. Differential endothelial regulation of OA tone may play a role in controlling blood flow and access of circulating factors to NG.

It takes two to thrombosis: Hemolysis and complement

Thromboembolic events represent the most common complication of hemolytic anemias characterized by complement-mediated hemolysis such as paroxysmal nocturnal hemoglobinuria and autoimmune hemolytic anemia. Similarly, atypical hemolytic uremic syndrome is characterized by hemolysis and thrombotic abnormalities. The main player in the development of thrombosis in hemolytic diseases is suggested to be the complement system. However, the release of extracellular hemoglobin and heme by hemolysis itself can also drive procoagulant responses. Both, complement activation and hemolysis promote the activation of neutrophils resulting in the formation of neutrophil extracellular traps and induce inflammation and vascular damage which all together might (synergistically) lead to hypercoagulability. In this review we aim to summarize the current knowledge on the role of complement activation and hemolysis in the onset of thrombosis in hemolytic diseases. This review will discuss the interplay between different biological systems and neutrophil activation contributing to the pathogenesis of thrombosis. Finally, we will combine this fundamental knowledge and address the pathophysiology of hemolysis in prototypical complement-driven diseases.

Tissue Homeostasis and Inflammation

There is a growing interest in understanding tissue organization, homeostasis, and inflammation. However, despite an abundance of data, the organizing principles of tissue biology remain poorly defined. Here, we present a perspective on tissue organization based on the relationships between cell types and the functions that they perform. We provide a formal definition of tissue homeostasis as a collection of circuits that regulate specific variables within the tissue environment, and we describe how the functional organization of tissues allows for the maintenance of both tissue and systemic homeostasis. This leads to a natural definition of inflammation as a response to deviations from homeostasis that cannot be reversed by homeostatic mechanisms alone. We describe how inflammatory signals act on the same cellular functions involved in normal tissue organization and homeostasis in order to coordinate emergency responses to perturbations and ultimately return the system to a homeostatic state. Finally, we consider the hierarchy of homeostatic and inflammatory circuits and the implications for the development of inflammatory diseases.

Beetroot as a Potential Functional Food for Cancer Chemoprevention, a Narrative Review

Patients with cancer are prone to several debilitating side effects including fatigue, insomnia, depression and cognitive disturbances. Beetroot (Beta vulgaris L.) as a health promoting functional food may be potentially beneficial in cancer. As a source of polyphenols, flavonoids, dietary nitrates and other useful nutrients, beetroot supplementation may provide a holistic means to prevent cancer and manage undesired effects associated with chemotherapy. The main aim of this narrative review is to discuss beetroot's nutrient composition, current studies on its potential utility in chemoprevention and cancer-related fatigue or treatment-related side effects such as cardiotoxicity. This review aims to provide the current status of knowledge and to identify the related research gaps in this area. The flavonoids and polyphenolic components present in abundance in beetroot support its significant antioxidant and anti-inflammatory capacities. Most in vitro and in vivo studies have shown promising results; however, the molecular mechanisms underlying chemopreventive and chemoprotective effects of beetroot have not been completely elucidated. Although recent clinical trials have shown that beetroot supplementation improves human performance, translational studies on beetroot and its functional benefits in managing fatigue or other symptoms in patients with cancer are still lacking.

In vitro anti-inflammatory potential of marine macromolecules cross-linked bio-composite scaffold on LPS stimulated RAW 264.7 macrophage cells for cartilage tissue engineering applications

Biomaterials serve as an integral component of tissue engineering. They are designed to provide architectural framework of native extracellular matrix so as to encourage cell growth and eventual tissue regeneration. Naturally occurring biopolymers as scaffolds offer options for cartilage tissue engineering due to anti-inflammatory, biocompatibility, biodegradability, low toxicity of degradation by-products and plasticity in processing into a variety of material formats. Here we studied in vitro anti-inflammatory potential of marine macromolecules cross-linked bio-composite scaffold composed of hydroxyapatite, alginate, chitosan and fucoidan named as HACF on LPS stimulated RAW 264.7 macrophage cells. The effects of HACF on the viability of RAW264.7 cells, nitrite level, intracellular ROS as well as the mRNA levels of NF-κB, iNOS, COX-2, TNF-α, IL-1β and IL-6 were examined in LPS induced RAW264.7 macrophage cells. The results revealed that HACF hydrogel scaffold exerts anti-inflammatory effect by inhibiting the production of ROS, suppress NF-kB translocation to the nucleus and thereby inhibiting the production of inflammatory mediators. Hence, our results confirm that HACF has a strong anti-oxidant capacity to inhibit inflammation associated gene expression by suppressing NF-kB signaling pathway. It clearly reveals the anti-oxidant and anti-inflammatory effect of HACF hydrogel scaffold on LPS induced RAW 264.7 cells.

Plasma hydrogen sulfide: A biomarker of Alzheimer's disease and related dementias

While heart disease remains a common cause of mortality, cerebrovascular disease also increases with age, and has been implicated in Alzheimer's disease and related dementias (ADRD). We have described hydrogen sulfide (H₂S), a signaling molecule important in vascular homeostasis, as a biomarker of cardiovascular disease. We hypothesize that plasma H₂S and its metabolites also relate to vascular and cognitive dysfunction in ADRD. We used analytical biochemical methods to measure plasma H₂S metabolites and MRI to evaluate indicators of microvascular disease in ADRD. Levels of total H₂S and specific metabolites were increased in ADRD versus controls. Cognition and microvascular disease indices were correlated with H₂S levels. Total plasma sulfide was the strongest indicator of ADRD, and partially drove the relationship between cognitive dysfunction and white matter lesion volume, an indicator of microvascular disease. Our findings show that H₂S is dysregulated in dementia, providing a potential biomarker for diagnosis and intervention.

Ginsenoside Rc Ameliorates Endothelial Insulin Resistance via Upregulation of Angiotensin-Converting Enzyme 2

Type 2 diabetes mellitus (T2DM) is a major health concern which may cause cardiovascular complications. Insulin resistance (IR), regarded as a hallmark of T2DM, is characterized by endothelial dysfunction. Ginsenoside Rc is one of the main protopanaxadiol-type saponins with relatively less research on it. Despite researches confirming the potent anti-inflammatory and antioxidant activities of ginsenoside Rc, the potential benefits of ginsenoside Rc against vascular complications have not been explored. In the present study, we investigated the effects of ginsenoside Rc on endothelial IR and endothelial dysfunction with its underlying mechanisms using high glucose- (HG-) cultured human umbilical vein endothelial cells (HUVECs) in vitro and a type 2 diabetic model of db/db mice in vivo. The results showed that ginsenoside Rc corrected the imbalance of vasomotor factors, reduced the production of Ang (angiotensin) II, and activated angiotensin-converting enzyme 2 (ACE2)/Ang-(1–7)/Mas axis in HG-treated HUVECs. Besides, ginsenoside Rc improved the impaired insulin signaling pathway and repressed oxidative stress and inflammatory pathways which constitute key factors leading to IR. Interestingly, the effects of ginsenoside Rc on HG-induced HUVECs were abolished by the selective ACE2 inhibitor MLN-4760. Furthermore, ginsenoside Rc exhibited anti-inflammatory as well as antioxidant properties and ameliorated endothelial dysfunction via upregulation of ACE2 in db/db mice, which were confirmed by the application of MLN-4760. In conclusion, our findings reveal a novel action of ginsenoside Rc and demonstrate that ginsenoside Rc ameliorated endothelial IR and endothelial dysfunction, at least in part, via upregulation of ACE2 and holds promise for the treatment of diabetic vascular complications.