Nitric oxide: an endogenous modulator of leukocyte adhesion

Salt-sensitive hypertension: role of endothelial and vascular dysfunction and sex

For the last 120 years, the contribution of salt has been identified in the pathophysiological elevation of blood pressure. Since then, both human and experimental murine studies have begun to elucidate the key mechanisms contributing to the development of salt-sensitive hypertension. Numerous mechanisms, including increased plasma volume, sodium retention, impaired autoregulatory capability, inflammation, and endothelial and vascular dysfunction, contribute to deleterious elevations in blood pressure during salt sensitivity. The endothelium plays a critical role in blood flow regulation, renal blood flow, and blood pressure elevations and in migrating immune cells to end-organs, contributing to end-organ damage and fibrosis. In this review, we will consider the clinical studies setting the foundation for the definition of salt-sensitive hypertension, murine models to study endothelial and vascular contributions, and endothelial cell cultures that have shed light on signaling mechanisms. Lastly, we will discuss the sex-dependent physiology and mechanisms contributing to salt-sensitive hypertension development and their clinical implications.

Neutrophil stalling does not mediate the increase in tau phosphorylation and the cognitive impairment associated with high salt diet

High dietary salt intake has powerful effects on cerebral blood vessels and has emerged as a risk factor for stroke and cognitive impairment. In mice, high salt diet (HSD) leads to reduced cerebral blood flow (CBF), tau hyperphosphorylation and cognitive dysfunction. However, it is still unclear whether the reduced CBF is responsible for the effects of HSD on tau and cognition. Capillary stalling has emerged as a cause of CBF reduction and cognitive impairment in models of Alzheimer's disease and diabetes. Therefore, we tested the hypothesis that capillary stalling also contributes to the CBF reduction and cognitive impairment in HSD. Using two-photon imaging, we found that HSD increased stalling of neutrophils in brain capillaries and decreased CBF. Neutrophil depletion reduced the number of stalled capillaries and restored resting CBF but did not prevent tau phosphorylation or cognitive impairment. These novel findings show that, capillary stalling contribute to CBF reduction in HSD, but not to tau phosphorylation and cognitive deficits. Therefore, the hypoperfusion caused by capillary stalling is not the main driver of the tau phosphorylation and cognitive impairment.

Looking below the surface: using intravital imaging to decipher inflammatory renal disease and renal cell injury

Renal function can be perturbed by a range of stimuli that cause cellular injury and inflammation in the kidney. These injurious and inflammatory processes are typically dynamic and progressive, involving the actions of highly migratory cells such as leukocytes and cellular responses that occur over time spans ranging from seconds to weeks. Understanding these dynamic responses has entailed the use of imaging technologies that allow visualization and capture of events over different time spans, ideally in intact organs in live, experimental animals. The technique that allows this is intravital imaging. Intravital imaging, particularly multiphoton intravital microscopy, has been crucial to the investigation of dynamic physiological and pathophysiological processes in the kidney for many years, driving key developments in our understanding of renal (patho)physiology. This includes the mechanisms of ultrafiltrate generation, the response to acute kidney injury, and how inflammatory leukocytes are recruited to and cause injury in the kidney. This review describes the key studies that have applied intravital imaging to the investigation of models of inflammatory renal disease. The responses examined include those restricted to the glomerulus and the effects of acute kidney injury on the tubulointerstitium. Future innovations and directions in this field of research are also discussed.

Global research trends on chronic thromboembolic pulmonary hypertension: a bibliometric analysis (January 2000-January 2024)

Background

Chronic thromboembolic pulmonary hypertension (CTEPH), a progressive disease, can lead to decompensation of the right half of the heart and death. Studies on CTEPH have increased in number over the last two decades. This study aimed to perform a bibliometric analysis of the global scientific output on CTEPH in the last 24 years to identify research trends and hot topics.

Methods

We searched the Web of Science Core Collection (WoSCC) Science Citation Index Expanded (Science Citation Index Expanded and Social Sciences Citation Index) for literature on CTEPH published from January 1, 2000 to January 31, 2024, and recorded their information. The Bibliometrix software package was used for bibliometric indicator analysis, and VOSviewer and CiteSpace were used to visualize trends and hotspots of CTEPH research.

Results

Overall, 2,264 publications were included in the bibliometric analysis. The number of annual publications increased drastically from 14 in 2000 to 199 in 2023. The number of publications on CTEPH has increased over the last two decades, with 24.4% (n=553) of the publications published in top academic journals. The United States ranked first in publications and had the best CTEPH-investigating institutions; it also had the highest level of international cooperation. Distinctively, 7 of the top 10 institutions and 7 of the top 10 researchers in the field were from Europe with the most influential scientists. A relatively high percentage of the publications were published in top-rank academic journals, especially in respirology and cardiology journals. Pulmonary endarterectomy (PEA) was the main therapy during the first decade, while balloon pulmonary angioplasty (BPA) and pulmonary arterial hypertension (PAH)-targeted medicine have recently gained interest. Dual-energy computed tomography (DECT), right ventricular function, and the role of pulmonary endothelium in microvasculopathy have become the focus of CTEPH research.

Conclusions

The number of publications on CTEPH has increased over the last two decades, and CTEPH has become a significant topic in both respirology and cardiology. Our results indicate that future research in this field will continue to focus on elucidating the pathophysiological mechanisms underlying this disorder, improving diagnostic accuracy, and developing novel imaging techniques. The integration of existing therapeutic modalities and the elucidation of right ventricular dysfunction are key areas of research.

Nutraceutical COMP-4 confers protection against endothelial dysfunction through the eNOS/iNOS-NO-cGMP pathway

The nutraceutical COMP-4 -consisting of L-citrulline, ginger extract, and herbal components Paullinia cupana and muira puama-has been shown previously to stimulate the production of nitric oxide (NO) in a variety of tissue types. We hypothesized that COMP-4 may have a protective, stimulatory effect on the vascular endothelial cell. Human umbilical arterial endothelial cells were incubated for 24 hours with or without COMP-4 and, to replicate impairment of endothelial function, co-incubated with or without H2O2. NO intracellular content, nitrite formation and cGMP content in culture media, nitric oxide synthase (NOS) isoforms and mRNA content, pro-inflammatory cytokines, and PAI-1 expression and activity were measured. COMP-4 increased endothelial cell production of NO and cGMP and the expression of both endothelial NOS (eNOS) and inducible NOS (iNOS), in tandem with a reduction in cytokine expression and activity of PAI-1. Co-incubation of COMP-4 with H2O2 reversed detrimental effects of H2O2 on endothelial function, evidenced by improvement in NO availability and abrogation of the pro-inflammatory milieu. These results suggest that COMP-4 exerts a stimulatory effect on endothelial cell eNOS and iNOS to increase NO bioavailability, leading to a reduction in pro-inflammatory cytokines, particularly the prothrombotic PAI-1.

Regulatory T Cell- and Natural Killer Cell-Mediated Inflammation, Cerebral Vasospasm, and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage-A Systematic Review and Meta-Analysis Approach

Aneurysmal subarachnoid hemorrhage (SAH) involves a significant influx of blood into the cerebrospinal fluid, representing a severe form of stroke. Despite advancements in aneurysm closure and neuro-intensive care, outcomes remain impaired due to cerebral vasospasm and delayed cerebral ischemia (DCI). Previous pharmacological therapies have not successfully reduced DCI while improving overall outcomes. As a result, significant efforts are underway to better understand the cellular and molecular mechanisms involved. This review focuses on the activation and effects of immune cells after SAH and their interactions with neurotoxic and vasoactive substances as well as inflammatory mediators. Particular attention is given to clinical studies highlighting the roles of natural killer (NK) cells and regulatory T cells (Treg) cells. Alongside microglia, astrocytes, and oligodendrocytes, NK cells and Treg cells are key contributors to the inflammatory cascade following SAH. Their involvement in modulating the neuro-inflammatory response, vasospasm, and DCI underscores their potential as therapeutic targets and prognostic markers in the post-SAH recovery process. We conducted a systematic review on T cell- and natural killer cell-mediated inflammation and their roles in cerebral vasospasm and delayed cerebral ischemia. We conducted a meta-analysis to evaluate outcomes and mortality in studies focused on NK cell- and T cell-mediated mechanisms.

Adropin: a key player in immune cell homeostasis and regulation of inflammation in several diseases

Adropin is a secreted peptide encoded by the energy homeostasis-associated gene (ENHO), located chromosome 9p13.3, with a conserved amino acid sequence across humans and mice. Its expression is regulated by various factors, including fat, LXRα, ERα, ROR, and STAT3. Adropin plays a critical role in glucose and lipid metabolism, as well as insulin resistance, by modulating multiple signaling pathways that contribute to the reduction of obesity and the improvement of blood lipid and glucose homeostasis. Additionally, it influences immune cells and inflammation, exerting anti-inflammatory effects across various diseases. While extensive research has summarized the regulation of cellular energy metabolism by adropin, limited studies have explored its role in immune regulation and inflammation. To enhance the understanding of adropin's immune-modulating and anti-inflammatory mechanisms, this review synthesizes recent findings on its effects in conditions such as atherosclerosis, diabetes, fatty liver, non-alcoholic hepatitis, and inflammation. Furthermore, the review discusses the current research limitations and outlines potential future directions for adropin-related investigations. It is hoped that ongoing research into adropin will contribute significantly to the advancement of medical treatments for various diseases.

The biological role and future therapeutic uses of nitric oxide in extracorporeal membrane oxygenation, a narrative review

BACKGROUND

Nitric oxide (NO) is a gas naturally produced by the human body that plays an important physiological role. Specifically, it binds guanylyl cyclase to induce smooth muscle relaxation. NO's other protective functions have been well documented, particularly its protective endothelial functions, effects on decreasing pulmonary vascular resistance, antiplatelet, and anticoagulation properties. The use of nitric oxide donors as vasodilators has been known since 1876. Inhaled nitric oxide has been used as a pulmonary vasodilator and to improve ventilation perfusion matching since the 1990s. It is currently approved by the United States Food and Drug Administration for neonates with hypoxic respiratory failure, however, it is used off-label for acute respiratory distress syndrome, acute bronchiolitis, and COVID-19.

PURPOSE

In this article we review the currently understood biological action and therapeutic uses of NO through nitric oxide donors such as inhaled nitric oxide. We will then explore recent studies describing use of NO in cardiopulmonary bypass and extracorporeal membrane oxygenation and speculate on NO's future uses.

The Role of Platelets in Atherosclerosis: A Historical Review

Atherosclerosis is a chronic, multifactorial inflammatory disorder of large and medium-size arteries, which is the leading cause of cardiovascular mortality and morbidity worldwide. Although platelets in cardiovascular disease have mainly been studied for their crucial role in the thrombotic event triggered by atherosclerotic plaque rupture, over the last two decades it has become clear that platelets participate also in the development of atherosclerosis, owing to their ability to interact with the damaged arterial wall and with leukocytes. Platelets participate in all phases of atherogenesis, from the initial functional damage to endothelial cells to plaque unstabilization. Platelets deposit at atherosclerosis predilection sites before the appearance of manifest lesions to the endothelium and contribute to induce endothelial dysfunction, thus supporting leukocyte adhesion to the vessel wall. In particular, platelets release matrix metalloproteinases, which interact with protease-activated receptor 1 on endothelial cells triggering adhesion molecule expression. Moreover, P-selectin and glycoprotein Ibα expressed on the surface of vessel wall-adhering platelets bind PSGL-1 and β2 integrins on leukocytes, favoring their arrest and transendothelial migration. Platelet-leukocyte interactions promote the formation of radical oxygen species which are strongly involved in the lipid peroxidation associated with atherosclerosis. Platelets themselves actively migrate through the endothelium toward the plaque core where they release chemokines that modify the microenvironment by modulating the function of other inflammatory cells, such as macrophages. While current antiplatelet agents seem unable to prevent the contribution of platelets to atherogenesis, the inhibition of platelet secretion, of the release of MMPs, and of some specific pathways of platelet adhesion to the vessel wall may represent promising future strategies for the prevention of atheroprogression.

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.

Improvement of the outcome of the saphenous vein graft when connected to the internal thoracic artery

Background

Since 2000, we have been grafting the right coronary artery system (RCAs) using the proximal portion of the right internal thoracic artery (RITA) as the inflow of the saphenous vein graft (SVG) to increase the number of patients undergoing beating heart complete myocardial revascularization.

Methods

From 2000 to 2022, 928 consecutive patients underwent SVG on the RCAs. In 546 patients (58.8%), the inflow was the RITA (I-graft group), and in 382 patients (41.2%), the inflow was the aorta (Ao-graft group). The inclusion criteria were age ≤75 years, ejection fraction >35%, only one SVG per patient, bilateral internal thoracic arteries as a Y-graft on the left system (three-vessel disease, n = 817, 88.0%) or left internal thoracic artery on the left anterior descending artery and RITA + SVG on the RCAs (two-vessel disease, n = 111, 12.0%). Propensity matching identified 306 patients per group. After a median follow-up of 8 (5-10) years, graft patency was assessed by coronary computed tomographic angiography in 132 patients (64 in the I-graft group and 68 in the Ao-graft group).

Results

Early results were similar in both groups. The I-graft group had higher 10-year survival and freedom from main adverse cardiac events (90.0 ± 2.0 vs. 80.6 ± 3.8, p = 0.0162, and 81.3 ± 2.7 vs. 64.7 ± 5.6, p = 0.0206, respectively). When RITA was the inflow, SVG had a higher estimated 10-year patency rate (82.8% ± 6.5 vs. 58.8% ± 7.4, p = 0.0026) and a smaller inner lumen diameter (2.7 ± 0.4 vs. 3.4 ± 0.6 mm, p < 0.0001).

Conclusion

When the inflow is the RITA, SVG grafted to the RCAs (I-graft) may result in a higher patency rate and better outcome than when the inflow is the ascending aorta (Ao-graft). The continuous supply of nitric oxide by RITA may be the cause of the higher patency rate of the I-graft, which can behave like an arterial conduit.

Development and Worsening of Hypertension with Age in Male Wistar Rats as a Physiological Model of Age-Related Hypertension: Correction of Hypertension with Taxifolin

To preclinically study the effectiveness of new antihypertensive drugs, various animal hypertension models are used. However, most of them do not correspond to primary hypertension, which develops in people with age. We used male Wistar rats of 4, 10, 12 and 18 months old. The animals were divided according to systolic blood pressure (SBP) into normotensive (SBP ≤ 114 mmHg) or hypertensive (SBP ≥ 115 mmHg). Within hypertensive animals, two cohorts were distinguished-with SBP below and above 125 mmHg. The animals received 100 µg/kg of taxifolin intraperitoneally for 7 days. A significant difference was shown between animals with SBP above and below 115 mmHg, as well as between cohorts of hypertensive animals with SBP above and below 125 mmHg within each age. The number of animals with elevated SBP increased with age both for clusters with an SBP above 115 mmHg and for cohorts with an SBP above 125 mmHg. Administration of taxifolin led to a significant decrease in the SBP only in hypertensive animals. A physiological model of age-related hypertension was obtained in male Wistar rats. It has been shown that hypertension develops and worsens with age. In preclinical studies, it should be taken into account that drugs may have different effects depending on the initial SBP of the animals.

Impact of Nitric Oxide on Polymorphonuclear Neutrophils' Function

BACKGROUND

There is increasing evidence that nitric oxide (nitrogen monoxide, NO) significantly influences immune cellular responses, including those from polymorphonuclear leukocytes (PMNs).

OBJECTIVE

The aim of this study was to examine a possible effect of NO on PMNs' function (chemotaxis, production of reactive oxygen species (ROS), and NETosis) using live cell imaging. Moreover, we investigated PMN surface epitope and neutrophil oxidative burst under the influence of NO by flow cytometric analysis.

METHODS

Whole blood samples were obtained from healthy volunteers, and PMNs were isolated by density centrifugation. Live cell imaging using type I collagen matrix in µSlide IBIDI chemotaxis chambers was conducted in order to observe N-formyl-L-methionyl-L-leucyl-phenylalanine (fMLP)-stimulated PMN chemotaxis, ROS production, and NETosis. In the test group, NO was continuously redirected into the climate chamber of the microscope, so the chemotaxis chambers were surrounded by NO. The same experimental setup without NO served as a control. In addition, isolated PMNs were incubated with nitrogen monoxide (NO) or without (the control). Subsequently, flow cytometry was used to analyze neutrophil antigen expression and oxidative burst.

RESULTS

Our live cell imaging results demonstrated a migration-promoting effect of NO on PMNs. We observed that in the case of prior stimulation by fMLP, NO has no effect on the time course of neutrophil ROS production and NET release. However, flow cytometric analyses demonstrated an increase in ROS production after pretreatment with NO. No NO-dependent differences for the expression of CD11b, CD62L, or CD66b could be observed.

CONCLUSIONS

We were able to demonstrate a distinct effect of NO on PMNs' function. The complex interaction between NO and PMNs remains a major research focus, as the exact mechanisms and additional influencing factors remain elusive. Future studies should explore how varying NO concentrations and the timing of NO exposure relative to PMN activation affect its influence.

Inhibitors of NLRP3 Inflammasome Formation: A Cardioprotective Role for the Gasotransmitters Carbon Monoxide, Nitric Oxide, and Hydrogen Sulphide in Acute Myocardial Infarction

Myocardial ischaemia reperfusion injury (IRI) occurring from acute coronary artery disease or cardiac surgical interventions such as bypass surgery can result in myocardial dysfunction, presenting as, myocardial "stunning", arrhythmias, infarction, and adverse cardiac remodelling, and may lead to both a systemic and a localised inflammatory response. This localised cardiac inflammatory response is regulated through the nucleotide-binding oligomerisation domain (NACHT), leucine-rich repeat (LRR)-containing protein family pyrin domain (PYD)-3 (NLRP3) inflammasome, a multimeric structure whose components are present within both cardiomyocytes and in cardiac fibroblasts. The NLRP3 inflammasome is activated via numerous danger signals produced by IRI and is central to the resultant innate immune response. Inhibition of this inherent inflammatory response has been shown to protect the myocardium and stop the occurrence of the systemic inflammatory response syndrome following the re-establishment of cardiac circulation. Therapies to prevent NLRP3 inflammasome formation in the clinic are currently lacking, and therefore, new pharmacotherapies are required. This review will highlight the role of the NLRP3 inflammasome within the myocardium during IRI and will examine the therapeutic value of inflammasome inhibition with particular attention to carbon monoxide, nitric oxide, and hydrogen sulphide as potential pharmacological inhibitors of NLRP3 inflammasome activation.

Clinical Effects of Nitric Oxide Added to the Oxygenator of Children on Extracorporeal Membrane Oxygenation: Pre-Post Cohort Study

Nitric oxide (NO) can be safely delivered through the sweep gas to the oxygenator of an extracorporeal membrane oxygenation (ECMO) circuit. It has theoretical benefits such as preventing platelet adhesion to surfaces, mitigating inflammatory response and protection against ischemia-reperfusion injury. In this uncontrolled before-after study of children on ECMO, the outcomes of those who received NO were compared with those who did not. Among 393 ECMO runs (from 337 patients), 192 of 393 (49%) received NO and 201 of 393 (51%) did not. The use of NO was associated with a 37% reduction in circuit change (adjusted risk ratio [aRR]: 0.63, 95% confidence interval [CI]: 0.42-0.93). The aRR (95% CI) for risk of neurologic injury was 0.72 (0.47-1.11). We observed potential heterogeneity of treatment effect for the risk of neurologic injury in children who had cardiac surgery: the risk with NO was lower in those who had cardiac surgery (aRR: 0.50, 95% CI: 0.26-0.96). There was no difference in survival between the study groups. In children managed with NO delivered through the ECMO circuit, we report a reduction in observed rate of circuit change and lower risk of neurologic injury in children who underwent cardiac surgery. Nitric oxide therapy on ECMO warrants prospective evaluation in children.

Endothelial LAT1 (SLC7A5) Mediates S-Nitrosothiol Import and Modulates Respiratory Sequelae of Red Blood Cell Transfusion In Vivo

BACKGROUND

 Increased adhesivity of red blood cells (RBCs) to endothelial cells (ECs) may contribute to organ dysfunction in malaria, sickle cell disease, and diabetes. RBCs normally export nitric oxide (NO)-derived vascular signals, facilitating blood flow. S-nitrosothiols (SNOs) are thiol adducts formed in RBCs from precursor NO upon the oxygenation-linked allosteric transition in hemoglobin. RBCs export these vasoregulatory SNOs on demand, thereby regulating regional blood flow and preventing RBC-EC adhesion, and the large (system L) neutral amino acid transporter 1 (LAT1; SLC7A5) appears to mediate SNO export by RBCs.

METHODS

 To determine the role of LAT1-mediated SNO import by ECs generally and of LAT1-mediated SNO import by ECs in RBC SNO-dependent modulation of RBC sequestration and blood oxygenation in vivo, we engineered LAT1fl/fl; Cdh5-Cre+ mice, in which the putative SNO transporter LAT1 can be inducibly depleted (knocked down, KD) specifically in ECs ("LAT1ECKD").

RESULTS

 We show that LAT1 in mouse lung ECs mediates cellular SNO uptake. ECs from LAT1ECKD mice (tamoxifen-induced LAT1fl/fl; Cdh5-Cre+) import SNOs poorly ex vivo compared with ECs from wild-type (tamoxifen-treated LAT1fl/fl; Cdh5-Cre-) mice. In vivo, endothelial depletion of LAT1 increased RBC sequestration in the lung and decreased blood oxygenation after RBC transfusion.

CONCLUSION

 This is the first study showing a role for SNO transport by LAT1 in ECs in a genetic mouse model. We provide the first direct evidence for the coordination of RBC SNO export with EC SNO import via LAT1. SNO flux via LAT1 modulates RBC-EC sequestration in lungs after transfusion, and its disruption impairs blood oxygenation by the lung.

Amino Acid Metabolism and Atherosclerotic Cardiovascular Disease

Despite significant advances in medical treatments and drug development, atherosclerotic cardiovascular disease (ASCVD) remains a leading cause of death worldwide. Dysregulated lipid metabolism is a well-established driver of ASCVD. Unfortunately, even with potent lipid-lowering therapies, ASCVD-related deaths have continued to increase over the past decade, highlighting an incomplete understanding of the underlying risk factors and mechanisms of ASCVD. Accumulating evidence over the past decades indicates a correlation between amino acids and disease state. This review explores the emerging role of amino acid metabolism in ASCVD, uncovering novel potential biomarkers, causative factors, and therapeutic targets. Specifically, the significance of arginine and its related metabolites, homoarginine and polyamines, branched-chain amino acids, glycine, and aromatic amino acids, in ASCVD are discussed. These amino acids and their metabolites have been implicated in various processes characteristic of ASCVD, including impaired lipid metabolism, endothelial dysfunction, increased inflammatory response, and necrotic core development. Understanding the complex interplay between dysregulated amino acid metabolism and ASCVD provides new insights that may lead to the development of novel diagnostic and therapeutic approaches. Although further research is needed to uncover the precise mechanisms involved, it is evident that amino acid metabolism plays a role in ASCVD.

Understanding Local Reactions Induced by Bothrops jararaca Venom: The Role of Inflammatory Mediators in Leukocyte-Endothelium Interactions

In recent years, extensive research has delved into the pathophysiology of local reactions triggered by Bothrops snake venoms. Even though antivenom works well at reducing death and systemic effects, it is still not very effective in treating local reactions because it cannot counteract damage that has already been triggered. This limitation might be attributed to certain molecules that amplify the venom-induced innate response. While evidence suggests endogenous mediators at the venom site play a role in this envenomation, in Brazil, the concurrent use of anti-inflammatory agents or other drugs alongside antivenom remains uncommon. This study evaluated the pharmacological mediation of alterations in leukocyte-endothelium interactions following the experimental envenomation of mice with Bothrops jararaca venom, the main culprit of snake-related accidents in Southeast Brazil. We treated envenomed mice with inhibitors of different pharmacological pathways and observed the cremaster muscle microcirculation with intravital microscopy. We found that eicosanoids related to cyclooxygenase pathways and nitric oxide significantly contributed to B. jararaca venom-induced alterations in leukocyte-endothelium interactions. Conversely, lipoxygenase-mediated eicosanoids, histamine, and serotonin had minimal participation. Notably, dexamethasone and antivenom treatment diminished B. jararaca venom-induced alterations in leukocyte-endothelium interactions. The limited efficacy of the antivenom in managing Bothrops venom-induced local reactions emphasizes the critical need for supplementary treatments to enhance therapeutic outcomes.

Nitric oxide: A potential etiological agent for vaso-occlusive crises in sickle cell disease

Nitric oxide (NO), a vasodilator contributes to the vaso-occlusive crisis associated with the sickle cell disease (SCD). Vascular nitric oxide helps in vasodilation, controlled platelet aggregation, and preventing adhesion of sickled red blood cells to the endothelium. It decreases the expression of pro-inflammatory genes responsible for atherogenesis associated with SCD. Haemolysis and activated endothelium in SCD patients reduce the bioavailability of NO which promotes the severity of sickle cell disease mainly causes vaso-occlusive crises. Additionally, NO depletion can also contribute to the formation of thrombus, which can cause serious complications such as stroke, pulmonary embolism etc. Understanding the multifaceted role of NO provides valuable insights into its therapeutic potential for managing SCD and preventing associated complications. Various clinical trials and studies suggested the importance of artificially induced nitric oxide and its supplements in the reduction of severity. Further research on the mechanisms of NO depletion in SCD is needed to develop more effective treatment strategies and improve the management of this debilitating disease.

A polyurethane-based hydrophilic elastomer with multi-biological functions for small-diameter vascular grafts

Thrombosis and intimal hyperplasia (IH) are two major problems faced by the small-diameter vascular grafts. Mimicking the native endothelium and physiological elasticity of blood vessels is considered an ideal strategy. Polyurethane (PU) is suitable for vascular grafts in mechanics because of its molecular designability and elasticity; however, it generally lacks the endothelium-like biofunctions and hydrophilicity. To solve this contradiction, a hydrophilic PU elastomer is developed by crosslinking the hydrophobic hard-segment chains containing diselenide with diaminopyrimidine-capped polyethylene glycol (PEG). In this network, the hydrophobic aggregation occurs underwater due to the uninterrupted hard-segment chains, leading to a significant self-enhancement in mechanics, which can be tailored to the elasticity similar to natural vessels by adjusting the crosslinking density. A series of in vitro studies confirm that the hydrophilicity of PEG and biological activities of aminopyrimidine and diselenide give the PU multi-biological functions similar to the native endothelium, including stable catalytic release of nitric oxide (NO) in the physiological level; anti-adhesion and anti-activation of platelets; inhibition of migration, adhesion, and proliferation of smooth muscle cells (SMCs); and antibacterial effect. In vivo studies further prove the good histocompatibility with both significant reduction in immune response and calcium deposition. STATEMENT OF SIGNIFICANCE: Constructing small-diameter vascular grafts similar to the natural vessels is considered an ideal method to solve the restenosis caused by thrombosis and intimal hyperplasia (IH). Because of the long-term stability, bulk modification is more suitable for implanted materials, however, how to achieve the biofunctions, hydrophilicity, and elasticity simultaneously is still a big challenge. In this work, a kind of polyurethane-based elastomer has been designed and prepared by crosslinking the functional long hard-segment chains with PEG soft segments. The underwater elasticity based on hydration-induced stiffening and the multi-biological functions similar to the native endothelium are compatible with natural vessels. Both in vitro and in vivo experiments demonstrate the potential of this PU as small-diameter vascular grafts.

Protective effects of Ruscus extract in combination with ascorbic acid and hesperidine methylchalcone on increased leukocyte-endothelial interaction and macromolecular permeability induced by ischemia reperfusion injury

BACKGROUND

Despite the well-recognized effectiveness of Ruscus aculetus extract combined or not with ascorbic acid (AA) and hesperidine methyl chalcone (HMC) on ischemia reperfusion (I/R) injury protection, little is known about the contribution of each constituent for this effect.

OBJECTIVE

To investigate the effects of AA and HMC combined or not with Ruscus extract on increased macromolecular permeability and leukocyte-endothelium interaction induced by I/R injury.

METHODS

Hamsters were treated daily during two weeks with filtered water (placebo), AA (33, 100 and 300 mg/kg/day) and HMC (50, 150 and 450 mg/kg/day) combined or not with Ruscus extract (50, 150 and 450 mg/kg/day). On the day of experiment, the cheek pouch microcirculation underwent 30 min of ischemia, and the number of rolling and adherent leukocytes and leaky sites were evaluated before ischemia and during 45 min of reperfusion.

RESULTS

Ruscus extract combined with AA and HMC (Ruscus extract mixture) significantly prevented post-ischemic increase in leukocyte rolling and adhesion and macromolecular permeability compared to placebo and these effects were more prominent than AA and HMC alone on leukocyte adhesion and macromolecular leakage.

CONCLUSION

Ruscus extract mixture were more effective than its isolated constituents in protect the hamster cheek pouch microcirculation against I/R injury.

Association between dietary intakes of Nitrate and Nitrite with Angina and atherogenic index in adults: A cross-sectional study from Tehran University of Medical Sciences employees` cohort (TEC) study

BACKGROUND

Previous studies have shown that the intake of nitrate and nitrite may be associated with cardiovascular disease. Therefore, this study sought to investigate the association between dietary intakes of nitrate and nitrite with the odds of angina and atherogenic index in adults.

METHODS

The study analyzed 1182 adults aged 20+ in the Tehran University of Medical Sciences (TUMS) Employee's Cohort study (TEC), focusing on dietary intakes, angina, and atherogenic indexes, using a validated food frequency questionnaire (FFQ) and the Rose Angina Questionnaire (RAQ).

RESULT

The study found a significant inverse relationship between nitrate intake and odds of grade 2 angina. The highest dietary nitrate was associated with 29 % lower odds of grade 1 angina and also, 46 % lower odds of angina possible (P<0.05). Adults with the highest nitrate intake had 29 % lower odds of grade 1 angina and 46 % lower odds of angina possible. Adherence to nitrate reduced CRI, Atherogenic index of plasma, and TyG in participants, but no significant association was found with other factors.

CONCLUSION

The study suggests that high nitrate and nitrite intake can alter angina risk, and a reverse association was found between dietary nitrate intake and various atherogenic indices.

Inhaled nitric oxide suppresses neuroinflammation in experimental ischemic stroke

Ischemic stroke is a major global health issue and characterized by acute vascular dysfunction and subsequent neuroinflammation. However, the relationship between these processes remains elusive. In the current study, we investigated whether alleviating vascular dysfunction by restoring vascular nitric oxide (NO) reduces post-stroke inflammation. Mice were subjected to experimental stroke and received inhaled NO (iNO; 50 ppm) after reperfusion. iNO normalized vascular cyclic guanosine monophosphate (cGMP) levels, reduced the elevated expression of intercellular adhesion molecule-1 (ICAM-1), and returned leukocyte adhesion to baseline levels. Reduction of vascular pathology significantly reduced the inflammatory cytokines interleukin-1β (Il-1β), interleukin-6 (Il-6), and tumor necrosis factor-α (TNF-α), within the brain parenchyma. These findings suggest that vascular dysfunction is responsible for leukocyte adhesion and that these processes drive parenchymal inflammation. Reversing vascular dysfunction may therefore emerge as a novel approach to diminish neuroinflammation after ischemic stroke and possibly other ischemic disorders.

Vascular aging and cardiovascular disease: pathophysiology and measurement in the coronary arteries

Age is a key risk factor for cardiovascular disease, including atherosclerosis. However, pathophysiological disease processes in the arteries are not an inevitable feature of aging. Large cohort studies with arterial phenotyping along with clinical and demographic data are essential to better understand factors related to the susceptibility or resilience to age-related vascular pathophysiology in humans. This review explores the mechanisms by which vascular structure and function alters with age, and how these changes relate to cardiovascular pathophysiology and disease. Features of vascular aging in the coronary arteries have historically been difficult to quantify pre-mortem due to their size and location. However, non-invasive imaging modalities including CT Coronary Angiogram are now being used to assess coronary vascular age, and further advances in imaging analysis such as the CT Fat Attenuation Index will help provide further measurement of features associated with coronary vascular aging. Currently, markers of vascular aging are not used as therapeutic targets in routine clinical practice, but non-pharmacological interventions including aerobic exercise and low salt diet, as well as anti-hypertensives have been demonstrated to reduce arterial stiffness. Advances in imaging technology, both in acquisition and advanced analysis, as well as harmonisation of measurements for researchers across the globe will be invaluable in understanding what constitutes healthy vascular aging and in identifying features of vascular aging that are associated with coronary artery disease and its adverse outcomes. Assessing such images in large cohorts can facilitate improved definitions of resilient and susceptible phenotypes to vascular aging in the coronary arteries. This is a critical step in identifying further risk factors and biomarkers within these groups and driving forward the development of novel therapies aimed at slowing or stopping age-related vascular changes in the coronary arteries.

Effects of Mechanical Stress on Endothelial Cells In Situ and In Vitro

Endothelial cells lining blood vessels are essential for maintaining vascular homeostasis and mediate several pathological and physiological processes. Mechanical stresses generated by blood flow and other biomechanical factors significantly affect endothelial cell activity. Here, we review how mechanical stresses, both in situ and in vitro, affect endothelial cells. We review the basic principles underlying the cellular response to mechanical stresses. We also consider the implications of these findings for understanding the mechanisms of mechanotransducer and mechano-signal transduction systems by cytoskeletal components.

S-Nitrosylation in endothelial cells contributes to tumor cell adhesion and extravasation during breast cancer metastasis

BACKGROUND

Nitric oxide is produced by different nitric oxide synthases isoforms. NO activates two signaling pathways, one dependent on soluble guanylate cyclase and protein kinase G, and other where NO post-translationally modifies proteins through S-nitrosylation, which is the modification induced by NO in free-thiol cysteines in proteins to form S-nitrosothiols. High levels of NO have been detected in blood of breast cancer patients and increased NOS activity has been detected in invasive breast tumors compared to benign or normal breast tissue, suggesting a positive correlation between NO biosynthesis, degree of malignancy and metastasis. During metastasis, the endothelium plays a key role allowing the adhesion of tumor cells, which is the first step in the extravasation process leading to metastasis. This step shares similarities with leukocyte adhesion to the endothelium, and it is plausible that it may also share some regulatory elements. The vascular cell adhesion molecule-1 (VCAM-1) expressed on the endothelial cell surface promotes interactions between the endothelium and tumor cells, as well as leukocytes. Data show that breast tumor cells adhere to areas in the vasculature where NO production is increased, however, the mechanisms involved are unknown.

RESULTS

We report that the stimulation of endothelial cells with interleukin-8, and conditioned medium from breast tumor cells activates the S-nitrosylation pathway in the endothelium to induce leukocyte adhesion and tumor cell extravasation by a mechanism that involves an increased VCAM-1 cell surface expression in endothelial cells. We identified VCAM-1 as an S-nitrosylation target during this process. The inhibition of NO signaling and S-nitrosylation blocked the transmigration of tumor cells through endothelial monolayers. Using an in vivo model, the number of lung metastases was inhibited in the presence of the S-nitrosylation inhibitor N-acetylcysteine (NAC), which was correlated with lower levels of S-nitrosylated VCAM-1 in the metastases.

CONCLUSIONS

S-Nitrosylation in the endothelium activates pathways that enhance VCAM-1 surface localization to promote binding of leukocytes and extravasation of tumor cells leading to metastasis. NAC is positioned as an important tool that might be tested as a co-therapy against breast cancer metastasis.

Effect of hypoxia on HIF-1α and NOS3 expressions in CD34+ cells of JAK2V617F-positive myeloproliferative neoplasms

PURPOSE

Myeloproliferative neoplasms (MPN) are a heterogeneous group of hematopoietic stem-cell diseases with excessive proliferation of one or more blood cell lines. In this study, we evaluated the effect of different oxygen concentrations on HIF-1α and NOS3 gene expression to determine the effect of the bone marrow microenvironment on JAK2V617F positive Philadelphia chromosome negative (Ph-) MPNs.

PATIENTS AND METHODS

Peripheral blood mononuclear cells (MNC) of 12 patients with Ph- MPN were collected. The presence of JAK2V617F allele status was determined with allele-specific nested PCR analysis. MPN CD34+ and CD34depleted populations were isolated from MNC by magnetic beads. Separate cell cultures of CD34+/depleted populations were managed at different oxygen concentrations including anoxia (∼0%), hypoxia (∼3%), and normoxia (∼20%) conditions for 24 ​h. HIF-1α and NOS3 gene expression changes were examined in each population related to JAK2V617F status with real time RT-PCR.

RESULT

It was revealed that relative HIF-1α and NOS3 expressions were significantly increased in response to decreased oxygen concentration in all samples. Relative HIF-1α and NOS3 expressions were found to be higher especially in CD34+ and CD34depleted populations carrying JAK2V617F mutations compared to MPN patients carrying wild-type JAK2.

CONCLUSION

JAK2V617F might have specific role in HIF-1α and NOS3 regulations with respect to low oxygen concentrations in Ph- MPN. Further evaluations might reveal the effect of JAK2V617F on Ph- MPN pathogenesis in bone marrow microenvironment.

NPRC deletion mitigated atherosclerosis by inhibiting oxidative stress, inflammation and apoptosis in ApoE knockout mice

Previous studies suggested a beneficial effect of natriuretic peptides in animal models of cardiovascular disease, but the role of natriuretic peptide receptor C (NPRC) in the pathogenesis of atherosclerosis (AS) remains unknown. This study was designed to test the hypothesis that NPRC may promote AS lesion formation and instability by enhancing oxidative stress, inflammation, and apoptosis via protein kinase A (PKA) signaling. ApoE-/- mice were fed chow or Western diet for 12 weeks and NPRC expression was significantly increased in the aortic tissues of Western diet-fed mice. Systemic NPRC knockout mice were crossed with ApoE-/- mice to generate ApoE-/-NPRC-/- mice, and NPRC deletion resulted in a significant decrease in the size and instability of aortic atherosclerotic lesions in ApoE-/-NPRC-/- versus ApoE-/- mice. In addition, endothelial cell-specific NPRC knockout attenuated atherosclerotic lesions in mice. In contrast, endothelial cell overexpression of NPRC aggravated the size and instability of atherosclerotic aortic lesions in mice. Experiments in vitro showed that NPRC knockdown in human aortic endothelial cells (HAECs) inhibited ROS production, pro-inflammatory cytokine expression and endothelial cell apoptosis, and increased eNOS expression. Furthermore, NPRC knockdown in HAECs suppressed macrophage migration, cytokine expression, and phagocytosis via its effects on endothelial cells. On the contrary, NPRC overexpression in endothelial cells resulted in opposite effects. Mechanistically, the anti-inflammation and anti-atherosclerosis effects of NPRC deletion involved activation of cAMP/PKA pathway, leading to downstream upregulated AKT1 pathway and downregulated NF-κB pathway. In conclusion, NPRC deletion reduced the size and instability of atherosclerotic lesions in ApoE-/- mice via attenuating inflammation and endothelial cell apoptosis and increasing eNOS expression by modulating cAMP/PKA-AKT1 and NF-κB pathways. Thus, targeting NPRC may provide a promising approach to the prevention and treatment of atherosclerosis.

The acute inflammatory response of teleost fish

Acute inflammation is crucial to the immune responses of fish. The process protects the host from infection and is central to induction of subsequent tissue repair programs. Activation of proinflammatory signals reshapes the microenvironment within an injury/infection site, initiates leukocyte recruitment, promotes antimicrobial mechanisms and contributes to the resolution of inflammation. Inflammatory cytokines and lipid mediators are primary contributors to these processes. Uncontrolled or persistent induction results in delayed tissue healing. The kinetics by which inducers and regulators of acute inflammation exert their actions is essential for understanding the pathogenesis of fish diseases and identifying potential treatments. Although, a number of these are well-conserved across, others are not, reflecting the unique physiologies and life histories of members of this unique animal group.

Molecular Mechanisms of Hyperoxia-Induced Neonatal Intestinal Injury

Oxygen therapy is important for newborns. However, hyperoxia can cause intestinal inflammation and injury. Hyperoxia-induced oxidative stress is mediated by multiple molecular factors and leads to intestinal damage. Histological changes include ileal mucosal thickness, intestinal barrier damage, and fewer Paneth cells, goblet cells, and villi, effects which decrease the protection from pathogens and increase the risk of necrotizing enterocolitis (NEC). It also causes vascular changes with microbiota influence. Hyperoxia-induced intestinal injuries are influenced by several molecular factors, including excessive nitric oxide, the nuclear factor-κB (NF-κB) pathway, reactive oxygen species, toll-like receptor-4, CXC motif ligand-1, and interleukin-6. Nuclear factor erythroid 2-related factor 2 (Nrf2) pathways and some antioxidant cytokines or molecules including interleukin-17D, n-acetylcysteine, arginyl-glutamine, deoxyribonucleic acid, cathelicidin, and health microbiota play a role in preventing cell apoptosis and tissue inflammation from oxidative stress. NF-κB and Nrf2 pathways are essential to maintain the balance of oxidative stress and antioxidants and prevent cell apoptosis and tissue inflammation. Intestinal inflammation can lead to intestinal damage and death of the intestinal tissue, such as in NEC. This review focuses on histologic changes and molecular pathways of hyperoxia-induced intestinal injuries to establish a framework for potential interventions.

Heterogenous improvements in endothelial function by sub-blood pressure lowering doses of ARBs result in major anti-aortic root remodeling effects

Low basal nitric oxide (NO) production is associated with a dysfunctional endothelium and vascular diseases. We have shown that some angiotensin II (AngII) receptor type 1 (AT1R) blockers (ARBs), a group of clinic-approved blood pressure (BP)-lowering medications, are also capable of activating endothelial function acutely and chronically, both ex vivo and in vivo, in pleiotropic, AngII-independent fashions, which suggested that endothelial function enhancement with ARBs may be independent of their well-documented BP lowering properties. Herein, we attempt to identify the most potent ARB at activating endothelial function when administered at sub-BP-lowering doses and determine its anti-aortic root remodeling properties in a model of Marfan syndrome (MFS). Amongst the 8 clinically available ARBs tested, only telmisartan and azilsartan induced significant (70% and 49%, respectively) NO-dependent inhibition of aortic contractility when administered for 4 weeks at sub-BP lowering, EC₅ doses. Low-dose telmisartan (0.47 mg/kg) attenuated MFS-associated aortic root widening, medial thickening, and elastic fiber fragmentation to the same degree as high-dose telmisartan (10 mg/kg) despite wide differences in BP lowering between the two doses. Our study suggests that telmisartan is the most potent ARB at promoting increased endothelial function at low sub-BP doses and that it retained major aortic root widening inhibition activities. ARBs may enhance endothelial function independently from BP-lowering pathways, which could lead to new therapeutic approaches.

Cellular Factors That Shape the Activity or Function of Nitric Oxide-Stimulated Soluble Guanylyl Cyclase

NO-stimulated guanylyl cyclase (SGC) is a hemoprotein that plays key roles in various physiological functions. SGC is a typical enzyme-linked receptor that combines the functions of a sensor for NO gas and cGMP generator. SGC possesses exclusive selectivity for NO and exhibits a very fast binding of NO, which allows it to function as a sensitive NO receptor. This review describes the effect of various cellular factors, such as additional NO, cell thiols, cell-derived small molecules and proteins on the function of SGC as cellular NO receptor. Due to its vital physiological function SGC is an important drug target. An increasing number of synthetic compounds that affect SGC activity via different mechanisms are discovered and brought to clinical trials and clinics. Cellular factors modifying the activity of SGC constitute an opportunity for improving the effectiveness of existing SGC-directed drugs and/or the creation of new therapeutic strategies.

Lipid phosphate phosphatase 3 maintains NO-mediated flow-mediated dilatation in human adipose resistance arterioles

Microvascular dysfunction predicts adverse cardiovascular events despite absence of large vessel disease. A shift in the mediator of flow-mediated dilatation (FMD) from nitric oxide (NO) to mitochondrial-derived hydrogen peroxide (H2 O2 ) occurs in arterioles from patients with coronary artery disease (CAD). The underlying mechanisms governing this shift are not completely defined. Lipid phosphate phosphatase 3 (LPP3) is a transmembrane protein that dephosphorylates lysophosphatidic acid, a bioactive lipid, causing a receptor-mediated increase in reactive oxygen species. A single nucleotide loss-of-function polymorphism in the gene coding for LPP3 (rs17114036) is associated with elevated risk for CAD, independent of traditional risk factors. LPP3 is suppressed by miR-92a, which is elevated in the circulation of patients with CAD. Repression of LPP3 increases vascular inflammation and atherosclerosis in animal models. We investigated the role of LPP3 and miR-92a as a mechanism for microvascular dysfunction in CAD. We hypothesized that modulation of LPP3 is critically involved in the disease-associated shift in mediator of FMD. LPP3 protein expression was reduced in left ventricle tissue from CAD relative to non-CAD patients (P = 0.004), with mRNA expression unchanged (P = 0.96). Reducing LPP3 expression (non-CAD) caused a shift from NO to H2 O2 (% maximal dilatation: Control 78.1 ± 11.4% vs. Peg-Cat 30.0 ± 11.2%; P < 0.0001). miR-92a is elevated in CAD arterioles (fold change: 1.9 ± 0.01 P = 0.04), while inhibition of miR-92a restored NO-mediated FMD (CAD), and enhancing miR-92a expression (non-CAD) elicited H2 O2 -mediated dilatation (P < 0.0001). Our data suggests LPP3 is crucial in the disease-associated switch in the mediator of FMD. KEY POINTS: Lipid phosphate phosphatase 3 (LPP3) expression is reduced in heart tissue patients with coronary artery disease (CAD). Loss of LPP3 in CAD is associated with an increase in the LPP3 inhibitor, miR-92a. Inhibition of LPP3 in the microvasculature of healthy patients mimics the CAD flow-mediated dilatation (FMD) phenotype. Inhibition of miR-92a restores nitric oxide-mediated FMD in the microvasculature of CAD patients.

Association of eNOS gene 4a/4b VNTR and T786C polymorphism with Crimean-Congo hemorrhagic fever

The most common viral hemorrhagic fever is Crimean-Congo hemorrhagic fever (CCHF). Endothelial nitric oxide synthase (eNOS) gene polymorphisms have been linked to both hemorrhagic fevers and viral diseases. The study's goal is to evaluate if the eNOS gene 4a/4b and T786C polymorphisms are related to CCHF. The study included 54 CCHF RNA-positive patients and 60 control subjects. The Bosphore CCHF virus Quantification Kit v1 was used to obtain CCHF RNA, and the Magnesia 16 isolation device was used to isolate DNA (Anatolia Gene works, Turkey). Polymerase chain reaction and restriction fragment length polymorphism were used to genotype the samples. The frequency of the eNOS 4a/4a, 4a/4b, and 4 b/4b genotypes in patients and the control was 6.6% versus 1.7%, 37.0% versus 43.3%, and 57.4% versus 55%, respectively. 4a: 24.07% of patients and 23.33% of controls; and 4 b: 75.92% of patients and 76.66% of controls. The frequency of the eNOS-786 T/C, T/T, T/C, and C/C genotypes in patients and the control group was 35.2% versus 68.3%; 51.9% versus 26.73%; and 13.0% versus 5.0%, respectively. The allele and genotype frequencies of the eNOS T786C variant differ statistically between patients and the control (p < 0.05). The eNOS T786C variant could be a genetic determinant for susceptibility to CCHF. To our knowledge, this is the first study to figure out the association between eNOS gene T786C polymorphisms and CCHF disease.

Impact of a Specific Collagen Peptide Food Supplement on Periodontal Inflammation in Aftercare Patients-A Randomised Controlled Trial

Background: This controlled clinical trial evaluated the impact of a specific collagen peptide food supplement on parameters of periodontal inflammation in aftercare patients. Methods: A total of 39 study patients were enrolled. At baseline, bleeding on probing (BoP; primary outcome), gingival index (GI), plaque control record (PCR), recession (REC) and probing pocket depth (PPD) for the calculation of the periodontal inflamed surface area (PISA) were documented. After subsequent professional mechanical plaque removal (PMPR), participants were randomly provided with a supply of sachets containing either a specific collagen peptide preparation (test group; n = 20) or a placebo (placebo group; n = 19) to be consumed dissolved in liquid once daily until reevaluation at day 90. Results: PMPR supplemented with the consumption of the specific collagen peptides resulted in a significantly lower mean percentage of persisting BoP-positive sites than PMPR plus placebo (test: 10.4% baseline vs. 3.0% reevaluation; placebo: 14.2% baseline vs. 9.4% reevaluation; effect size: 0.86). Mean PISA and GI values were also reduced compared to baseline, with a significant difference in favor of the test group (PISA test: 170.6 mm2 baseline vs. 53.7 mm2 reevaluation; PISA placebo: 229.4 mm2 baseline vs. 184.3 mm2 reevaluation; GI test: 0.5 baseline vs. 0.1 reevaluation; GI placebo: 0.4 baseline vs. 0.3 reevaluation). PCR was also significantly decreased in both experimental groups at revaluation, but the difference between the groups did not reach the level of significance. Conclusions: The supplementary intake of specific collagen peptides may further enhance the anti-inflammatory effect of PMPR in periodontal recall patients.

Soluble guanylyl cyclase: Molecular basis for ligand selectivity and action in vitro and in vivo

Nitric oxide (NO), carbon monoxide (CO), oxygen (O₂), hydrogen sulfide (H₂S) are gaseous molecules that play important roles in the physiology and pathophysiology of eukaryotes. Tissue concentrations of these physiologically relevant gases vary remarkable from nM range for NO to high μM range of O₂. Various hemoproteins play a significant role in sensing and transducing cellular signals encoded by gaseous molecules or in transporting them. Soluble guanylyl cyclase (sGC) is a hemoprotein that plays vital roles in a wide range of physiological functions and combines the functions of gaseous sensor and signal transducer. sGC uniquely evolved to sense low non-toxic levels of NO and respond to elevated NO levels by increasing its catalytic ability to generate the secondary signaling messenger cyclic guanosine monophosphate (cGMP). This review discusses sGC's gaseous ligand selectivity and the molecular basis for sGC function as high-affinity and selectivity NO receptor. The effects of other gaseous molecules and small molecules of cellular origin on sGC's function are also discussed.

Homeostatic medicine: a strategy for exploring health and disease

Homeostasis is a process of dynamic balance regulated by organisms, through which they maintain an internal stability and adapt to the external environment for survival. In this paper, we propose the concept of utilizing homeostatic medicine (HM) as a strategy to explore health and disease. HM is a science that studies the maintenance of the body’s homeostasis. It is also a discipline that investigates the role of homeostasis in building health, studies the change of homeostasis in disease progression, and explores ways to restore homeostasis for the prevention, diagnosis and treatment of disease at all levels of biological organization. A new dimension in the medical system with a promising future HM focuses on how homeostasis functions in the regulation of health and disease and provides strategic directions in disease prevention and control. Nitric oxide (NO) plays an important role in the control of homeostasis in multiple systems. Nitrate is an important substance that regulates NO homeostasis through the nitrate-nitrite-NO pathway. Sialin interacts with nitrate and participates in the regulation of NO production and cell biological functions for body homeostasis. The interactions between nitrate and NO or sialin is an important mechanism by which homeostasis is regulated.

Endothelial cell-specific loss of eNOS differentially affects endothelial function

The endothelium maintains and regulates vascular homeostasis mainly by balancing interplay between vasorelaxation and vasoconstriction via regulating Nitric Oxide (NO) availability. Endothelial nitric oxide synthase (eNOS) is one of three NOS isoforms that catalyses the synthesis of NO to regulate endothelial function. However, eNOS’s role in the regulation of endothelial function, such as cell proliferation and migration remain unclear. To gain a better understanding, we genetically knocked down eNOS in cultured endothelial cells using sieNOS and evaluated cell proliferation, migration and also tube forming potential in vitro. To our surprise, loss of eNOS significantly induced endothelial cell proliferation, which was associated with significant downregulation of both cell cycle inhibitor p21 and cell proliferation antigen Ki-67. Knockdown of eNOS induced cell migration but inhibited formation of tube-like structures in vitro. Mechanistically, loss of eNOS was associated with activation of MAPK/ERK and inhibition of PI3-K/AKT signaling pathway. On the contrary, pharmacologic inhibition of eNOS by inhibitors L-NAME or L-NMMA, inhibited cell proliferation. Genetic and pharmacologic inhibition of eNOS, both promoted endothelial cell migration but inhibited tube-forming potential. Our findings confirm that eNOS regulate endothelial function by inversely controlling endothelial cell proliferation and migration, and by directly regulating its tube-forming potential. Differential results obtained following pharmacologic versus genetic inhibition of eNOS indicates a more complex mechanism behind eNOS regulation and activity in endothelial cells, warranting further investigation.

Sulforaphane Regulates eNOS Activation and NO Production via Src-Mediated PI3K/Akt Signaling in Human Endothelial EA.hy926 Cells

Sulforaphane (SFN) is a naturally occurring isothiocyanate that is abundant in many cruciferous vegetables, such as broccoli and cauliflower, and it has been observed to exert numerous biological activities. In the present study, we investigate the effect of SFN on eNOS, a key regulatory enzyme of vascular homeostasis and underlying intracellular pathways, in human endothelial EA.hy926 cells. The results indicate that SFN treatment significantly increases NO production and eNOS phosphorylation in a time- and dose-dependent fashion and also augments Akt phosphorylation in a time- and dose-dependent manner. Meanwhile, pretreatment with LY294002 (a specific PI3K inhibitor) suppresses the phosphorylation of eNOS and NO production. Furthermore, SFN time- and dose-dependently induces the phosphorylation of Src kinase, a further upstream regulator of PI3K, while PP2 pretreatment (a specific Src inhibitor) eliminates the increase in phosphorylated Akt, eNOS and the production of NO derived from eNOS. Overall, the present study uncovers a novel effect of SFN to stimulate eNOS activity in EA.hy926 cells by regulating NO bioavailability. These findings provide clear evidence that SFN regulates eNOS activity and NO bioavailability, suggesting a promising therapeutic candidate to prevent endothelial dysfunction, atherosclerosis and other cardiovascular diseases.

Delayed cerebral ischemia: A look at the role of endothelial dysfunction, emerging endovascular management, and glymphatic clearance

Delayed cerebral ischemia (DCI) contributes to extensive morbidity and mortality for patients with aneurysmal subarachnoid hemorrhage (SAH). Recent contributions to the basic and translational investigation of DCI have shed light on emerging concepts that may aid in the development of novel therapeutics. A clear association between cerebral vasospasm (CV) and DCI exists, but it is also known that DCI can affect brain parenchyma remote from sites of vasospasm. In this review, we highlight the most recent contributions to the understanding of the underlying pathophysiology of DCI including the emerging role of the glymphatic system. Furthermore, we discuss treatments for DCI, including both pharmacologic therapies and endovascular treatment of vasospasm. There continues to be a disconnect between interventions and targeted treatment against pathophysiology. This review is intended to serve as a catalyst for further research and discovery that can aid in improved treatment options for DCI.

Nitric oxide improves regeneration and prevents calcification in bio-hybrid vascular grafts via regulation of vascular stem/progenitor cells

Vascular bypass surgery continues to use autologous grafts and often suffers from a shortage of donor grafts. Decellularized xenografts derived from porcine veins provide a promising candidate because of their abundant availability and low immunogenicity. Unfortunately, transplantation outcomes are far from satisfactory because of insufficient regeneration and adverse pathologic remodeling. Herein, a nitrate-functionalized prosthesis has been incorporated into a decellularized porcine vein graft to fabricate a bio-hybrid vascular graft with local delivery of nitric oxide (NO). Exogenous NO efficiently promotes vascular regeneration and attenuates intimal hyperplasia and vascular calcification in both rabbit and mouse models. The underlying mechanism was investigated using a Sca1 2A-CreER; Rosa-RFP genetic-lineage-tracing mouse model that reveals that Sca1⁺ stem/progenitor cells (SPCs) are major contributors to vascular regeneration and remodeling, and NO plays a critical role in regulating SPC fate. These results support the translational potential of this off-the-shelf vascular graft.

Short isocapnic hyperoxia affects indices of vascular remodeling and intercellular adhesion molecules in healthy men

In preparation for tracheal intubation during induction of anesthesia, the patient may be ventilated with 100% oxygen. To investigate the impact of acute isocapnic hyperoxia on endothelial activation and vascular remodeling, ten healthy young men (24±3 years) were exposed to 5-min normoxia (21% O2) and 10-min hyperoxia trials (100% O2). During hyperoxia, intercellular adhesion molecules (ICAM-1) (hyperoxia: 4.16±0.85 vs normoxia: 3.51±0.84 ng/mL, P=0.04) and tissue inhibitor matrix metalloproteinase 1 (TIMP-1) (hyperoxia: 8.40±3.84 vs normoxia: 5.73±2.15 pg/mL, P=0.04) increased, whereas matrix metalloproteinase (MMP-9) activity (hyperoxia: 0.53±0.11 vs normoxia: 0.68±0.18 A.U., P=0.03) decreased compared to the normoxia trial. We concluded that even short exposure to 100% oxygen may affect endothelial activation and vascular remodeling.

Inhaled nitric oxide improves post-cardiac arrest outcomes via guanylate cyclase-1 in bone marrow-derived cells

RATIONALE

Nitric oxide (NO) exerts its biological effects primarily via activation of guanylate cyclase (GC) and production of cyclic guanosine monophosphate. Inhaled NO improves outcomes after cardiac arrest and cardiopulmonary resuscitation (CPR). However, mechanisms of the protective effects of breathing NO after cardiac arrest are incompletely understood.

OBJECTIVE

To elucidate the mechanisms of beneficial effects of inhaled NO on outcomes after cardiac arrest.

METHODS

Adult male C57BL/6J wild-type (WT) mice, GC-1 knockout mice, and chimeric WT mice with WT or GC-1 knockout bone marrow were subjected to 8 min of potassium-induced cardiac arrest to determine the role of GC-1 in bone marrow-derived cells. Mice breathed air or 40 parts per million NO for 23 h starting at 1 h after CPR.

RESULTS

Breathing NO after CPR prevented hypercoagulability, cerebral microvascular occlusion, an increase in circulating polymorphonuclear neutrophils and neutrophil-to-lymphocyte ratio, and right ventricular dysfunction in WT mice, but not in GC-1 knockout mice, after cardiac arrest. The lack of GC-1 in bone marrow-derived cells diminished the beneficial effects of NO breathing after CPR.

CONCLUSIONS

GC-dependent signaling in bone marrow-derived cells is essential for the beneficial effects of inhaled NO after cardiac arrest and CPR.

Pleiotropic activation of endothelial function by angiotensin II receptor blockers is crucial to their protective anti-vascular remodeling effects

There are no therapeutics that directly enhance chronic endothelial nitric oxide (NO) release, which is typically associated with vascular homeostasis. In contrast, angiotensin II (AngII) receptor type 1 (AT1R) blockers (ARBs) can attenuate AngII-mediated oxidative stress, which often leads to increased endothelial NO bioavailability. Herein, we investigate the potential presence of direct, AngII/AT1R-independent ARB class effects on endothelial NO release and how this may result in enhanced aortic wall homeostasis and endothelial NO-specific transcriptome changes. Treatment of mice with four different ARBs induced sustained, long-term inhibition of vascular contractility by up to 82% at 16 weeks and 63% at 2 weeks, an effect reversed by L-NAME and absent in endothelial NO synthase (eNOS) KO mice or angiotensin converting enzyme inhibitor captopril-treated animals. In absence of AngII or in tissues with blunted AT1R expression or incubated with an AT2R blocker, telmisartan reduced vascular tone, supporting AngII/AT1R-independent pleiotropism. Finally, telmisartan was able to inhibit aging- and Marfan syndrome (MFS)-associated aortic root widening in NO-sensitive, BP-independent fashions, and correct aberrant TGF-β signaling. RNAseq analyses of aortic tissues identified early eNOS-specific transcriptome reprogramming of the aortic wall in response to telmisartan. This study suggests that ARBs are capable of major class effects on vasodilatory NO release in fashions that may not involve blockade of the AngII/AT1R pathway. Broader prophylactic use of ARBs along with identification of non-AngII/AT1R pathways activated by telmisartan should be investigated.

3β-Hydroxy-5β-hydroxy-B-norcholestane-6β-carboxaldehyde (SEC-B) Induces Proinflammatory Activation of Human Endothelial Cells Associated with Nitric Oxide Production and Endothelial Nitric Oxide Synthase/Caveolin-1 Dysregulation

Oxysterols are a family of 27-carbon cholesterol oxidation derivatives found in low-density lipoproteins (LDLs) and atherosclerotic plaques where they trigger several biological responses involved in the initiation and progression of atherosclerosis. Several pieces of evidence suggest that oxysterols contribute to endothelial dysfunction (ED) due to their ability to alter membrane fluidity and cell permeability leading to inflammation, oxidative stress and apoptosis. The present study aimed to investigate the molecular events occurring in human microvascular endothelial cells (HMEC-1) in response to autoxidation-generated 3β-hydroxy-5β-hydroxy-B-norcholestane-6β-carboxaldehyde (SEC-B) exposure. Our results highlight that SEC-B rapidly activates HMEC-1 by inducing oxidative stress, nitric oxide (NO) production and pro-inflammatory cytokine release. Exposure to SEC-B up to 24 h results in persistent accumulation of the vasodilator NO paralleled by an upregulation of the endothelial nitric oxide synthase (eNOS) enzyme and downregulation of Caveolin-1 (Cav-1) protein levels. Moreover, reduced expression and extracellular release of the vasoconstrictor factor endothelin-1 (ET-1) are observed. Furthermore, SEC-B stimulates the expression of the cytokines interleukin-6 (IL-6) and tumor necrosis factor-like weak inducer of apoptosis (TWEAK). This proinflammatory state leads to increased monocyte recruitment on activated HMEC-1 cells. Our findings add new knowledge on the role of SEC-B in ED and further support its potential implication in atherosclerosis.