Nitric oxide: an endogenous modulator of leukocyte adhesion

Tissue-Protective Mechanisms of Bioactive Phytochemicals in Flap Surgery

Despite careful preoperative planning, surgical flaps are prone to ischemic tissue damage and ischemia–reperfusion injury. The resulting wound breakdown and flap necrosis increase both treatment costs and patient morbidity. Hence, there is a need for strategies to promote flap survival and prevent ischemia-induced tissue damage. Phytochemicals, defined as non-essential, bioactive, and plant-derived molecules, are attractive candidates for perioperative treatment as they have little to no side effects and are well tolerated by most patients. Furthermore, they have been shown to exert beneficial combinations of pro-angiogenic, anti-inflammatory, anti-oxidant, and anti-apoptotic effects. This review provides an overview of bioactive phytochemicals that have been used to increase flap survival in preclinical animal models and discusses the underlying molecular and cellular mechanisms.

On the Role of Dietary Nitrate in the Maintenance of Systemic and Oral Health

The assessment of the significance of nitrates ingested with food has undergone a fundamental change in recent years after many controversial discussions. While for a long time, a diet as low in nitrates as possible was advocated on the basis of epidemiological data suggesting a cancer-promoting effect of nitrate-rich diets, more recent findings show that dietary nitrate, after its conversion to nitrite by nitrate-reducing bacteria of the oral microbiota, is an indispensable alternative source for the formation of nitric oxide (NO), which comprises a key element in the physiology of a variety of central body functions such as blood pressure control, defense against invading bacteria and maintenance of a eubiotic microbiota in the gut and oral cavity. This compact narrative review aims to present the evidence supported by clinical and in vitro studies on the ambivalent nature of dietary nitrates for general and oral health and to explain how the targeted adjuvant use of nitrate-rich diets could open new opportunities for a more cause-related control of caries and periodontal disease.

White Wine—Induced Endothelium-Dependent Vasorelaxation in Sprague-Dawley Rats

The vasodilatory activity and polyphenolic content of commercially available white wine is low compared to red wines. This study assessed the vasodilator potential of white wines produced by four different fermentation processes: (1) white wine produced by the standard procedure; (2) grapes left to macerate completely for 30 days; (3) grapes left to macerate up to half of unfermented sugar; and (4) wine produced by cooling the must. All tested wine samples were analyzed for their phenolic content, antioxidant capacity, and ethanol content. Vasodilation was examined in the norepinephrine pre-contracted isolated rat aortas of male Sprague-Dawley rats randomly exposed to cumulative concentrations (0.1‰ to 8‰ final dilutions in organ baths) of each of the tested wine samples with or without quercetin and/or gallic acid supplementation, in the absence/presence of NOS inhibitor L-NAME. Standard procedure and the procedure involving must cooling gives wine with lower phenolic content, antioxidant capacity, and lower vasodilator potential, respectively. L-NAME inhibited vasodilation to all wine samples. Quercetin with or without gallic acid supplementation restored vasodilation. Results show that vasodilation to white wine is NO-dependent and suggest the possibility of increasing the antioxidant capacity and vasodilatory potential of white wine using different production procedures, depending on quercetin content.

Effects of Thrombin on the Neurovascular Unit in Cerebral Ischemia

Cerebral ischemia is a cerebrovascular disease with high morbidity and mortality that poses a significant burden on society and the economy. About 60% of cerebral ischemia is caused by thrombus, and the formation of thrombus proceeds from insoluble fibrin, following its transformation from liquid fibrinogen. In thrombus-induced ischemia, increased permeability of the blood-brain barrier (BBB), followed by the extravasation of blood components into the brain results in an altered brain microenvironment. Changes in the brain microenvironment affect brain function and the neurovascular unit (NVU), the working unit of the brain. Recent studies have reported that coagulation factors interact with the NVU and its components, but the specific function of this interaction is highly speculative and warrants further investigations. In this article, we reviewed the role of coagulation factors in cerebral ischemia and the role of coagulation factors in thrombosis. Additionally, the influence of thrombin on the NVU is introduced, as well as in the function of NVU, which may help to explore part of brain injury mechanism during ischemia. Lastly, we propose some novel therapeutic approaches on ischemic stroke by reducing the risk of coagulation.

Dermal Microvascular Units in Domestic Pigs (Sus scrofa domestica): Role as Transdermal Passive Immune Channels

The dermal microvascular unit (DMU) is a perivascular functional unit in the dermis. It is composed of microvascular and capillary lymphatics surrounded by immune cells. In this study, jet needle-free injection system was used to injected biocompatible carbon nanoparticles into the cervical skin of domestic pigs (Sus scrofa domestica) and assessed the morphological distribution of DMUs by hematoxylin erythrosine staining, immunohistochemistry (IHC), and transmission electron microscopy (TEM), and TEM was also used to observe the ultrastructural changes of DMUs after jet needle-free injection. Following our study, we identified DMUs in the dermis stratum papillare and similar structures in the dermis stratum reticulare, but the aggregation of CD68⁺ and CD1a⁺ cells in the dermis stratum papillare of DMUs by IHC confirmed that DMUs act as reservoirs of dermal immune cells, while similar structures in the dermis stratum reticulare should not be considered as DMUs. Ultrastructure of DMUs was revealed by TEM. Marvelous changes were found following xenobiotics attack, including the rearrangement of endothelial cells and pericytes, and the reactivity of immune cells. Novel interstitial cell telocyte (TC) was also identified around the microvasculature, which may have been previously known as the veil cell. Our results successfully identified the distribution of DMUs in the skin of domestic pigs, which might act as reservoirs of immune cells in the skin and play a role in immune surveillance and immune defense.

Nitric Oxide Delivering Surfaces: An Overview of Functionalization Strategies and Efficiency Progress

An overview on the design of nitric oxide (NO) delivering surfaces for biomedical purposes is provided, with a focus on the advances of the past 5 years. A localized supply of NO is of a particular interest due to the pleiotropic biological effects of this diatomic compound. Depending on the generated NO flux, the surface can mimic a physiological release profile to provide an activity on the vascular endothelium or an antibacterial activity. Three requirements are considered to describe the various strategies leading to a surface delivering NO. Firstly, the coating must be selected in accordance with the properties of the substrate (nature, shape, dimensions…). Secondly, the releasing and/or generating kinetics of NO should match the targeted biological application. Currently, the most promising structures are developed to provide an adaptable NO supply driven by pathophysiological needs. Finally, the biocompatibility and the stability of the surface must also be considered regarding the expected residence time of the device. A critical point of view is proposed to help readers in the design of the NO delivering surface according to its expected requirement and therapeutic purpose.

The Dipeptidyl Peptidase-4 Inhibitor Linagliptin Ameliorates Endothelial Inflammation and Microvascular Thrombosis in a Sepsis Mouse Model

The pathophysiology of sepsis involves inflammation and hypercoagulability, which lead to microvascular thrombosis and compromised organ perfusion. Dipeptidyl peptidase (DPP)-4 inhibitors, e.g., linagliptin, are commonly used anti-diabetic drugs known to exert anti-inflammatory effects. However, whether these drugs confer an anti-thrombotic effect that preserves organ perfusion in sepsis remains to be investigated. In the present study, human umbilical vein endothelial cells (HUVECs) were treated with linagliptin to examine its anti-inflammatory and anti-thrombotic effects under tumor necrosis factor (TNF)-α treatment. To validate findings from in vitro experiments and provide in vivo evidence for the identified mechanism, a mouse model of lipopolysaccharide (LPS)-induced systemic inflammatory response syndrome was used, and pulmonary microcirculatory thrombosis was measured. In TNF-α-treated HUVECs and LPS-injected mice, linagliptin suppressed expressions of interleukin-1β (IL-1β) and intercellular adhesion molecule 1 (ICAM-1) via a nuclear factor-κB (NF-κB)–dependent pathway. Linagliptin attenuated tissue factor expression via the Akt/endothelial nitric oxide synthase pathway. In LPS-injected mice, linagliptin pretreatment significantly reduced thrombosis in the pulmonary microcirculation. These anti-inflammatory and anti-thrombotic effects were independent of blood glucose level. Together the present results suggest that linagliptin exerts protective effects against endothelial inflammation and microvascular thrombosis in a mouse model of sepsis.

Association of Endothelial Nitric Oxide Synthase Gene Polymorphisms with Coronary Artery Disease in North Indian Punjabi Population

Nitric oxide (NO) a potent vasodilator synthesized by endothelial cells has anti-atherosclerotic properties and maintains vascular tone. It has been documented that its reduced bioavailability in vascular endothelium plays an important role in the development and progression of coronary artery disease (CAD). Therefore, we aimed to investigate the association of - 786 T > C and 894 G > T polymorphisms of eNOS with CAD. This study included 211 CAD patients and 260 controls of North Indian Punjabi population. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Logistic regression analysis revealed that the TC and CC genotypes of - 786 T > C were significantly associated with the higher risk of CAD (OR: 2.00, p = 0.001: OR: 4.63, p = 0.001, respectively). Similarly, the GT and TT genotypes of 894 G > T were found to be significantly associated with the higher risk of CAD (OR: 1.96, p = 0.001; OR: 4.54, p = 0.005, respectively). Moreover, the recessive model in  - 786 T > C (OR: 3.58, p = 0.002) and 894 G > T (OR: 3.62, p = 0.009) polymorphisms provided 3.6-fold increased risk for CAD. Furthermore, the CG, TT, and CT haplotypes were also associated with the increased risk of CAD (OR: 2.1, p = 0.001; OR: 2, p = 0.002; OR: 3.1, p = 0.001, respectively). In addition, the CC genotype of - 786 T > C and GT genotype of 894 G > T were significantly associated with higher levels of triglycerides (TG) and very low-density lipoproteins cholesterol (VLDL-C). The present study reported the association of - 786 T > C and 894 G > T polymorphisms of eNOS with CAD and abnormal lipid levels in North Indian Punjabi population.

Chronic thromboembolic pulmonary hypertension: the magic of pathophysiology

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare and underdiagnosed complication of acute pulmonary embolism (APE). CTEPH is a common cause of pulmonary hypertension (PH) with distinct management strategy including pulmonary endarterectomy, balloon pulmonary angioplasty, long-term anticoagulation and PH drugs targeting endothelial cell dysfunction. Initially, PH in chronic thromboembolic pulmonary disease (CTEPD) was thought to be due exclusively to the intravascular obstruction of pulmonary arteries by unresolved fibrotic clots. However, it is now well accepted that pulmonary vascular remodelling can include significant pulmonary microvasculopathy, which plays a role in the development of CTEPH. The histological description and clinical consequences of CTEPH microvasculopathy are now better understood. These lesions may involve not only small muscular pulmonary arteries <500 µm, but also pulmonary capillaries and veins. In addition, enlargement and proliferation of systemic bronchial arteries as well as anastomoses between the systemic and pulmonary circulations contribute to the development of microvasculopathy. In this review, we discuss the recent advances in the understanding of the pathophysiology of CTEPH.

Phytochemical Contents and Pharmacological Potential of Parkia speciosa Hassk. for Diabetic Vasculopathy: A Review

Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycemia and is considered a major health problem in the world. It is associated with endothelial dysfunction which causes progressive vascular damage. DM is a known risk factor for atherosclerosis and cardiovascular complications such as peripheral artery disease, coronary artery disease, and stroke. Medicinal plants may act as an alternative resource or adjunctive treatment option in the treatment of diabetes and its cardiovascular complications. Parkia speciosa (Fabaceae) is a plant found abundantly in the Southeast Asian region. Its seeds, with or without pods, and roots have long been used as a traditional medicine in this region to treat hypertension and diabetes. Studies have shown its numerous beneficial pharmacological properties. Extracts of P. speciosa, particularly from its seeds and empty pods, show the presence of polyphenols. They also exhibit potent antioxidant, hypoglycemic, anti-inflammatory, and antihypertensive properties. Its hypoglycemic properties are reported to be associated with the presence of β-sitosterol, stigmasterol, and stigmat-4-en-3-one. The current review aimed to provide an overview of the current status of P. speciosa, its pharmacological potential, and its phytochemical content in attenuating diabetic vasculopathy. Glycemic status, oxidative stress, inflammation, and hyperlipidemia are known to play pivotal roles in the initiation and severity of diabetic cardiovascular diseases; thus, targeting these factors might be beneficial for preventing and/or treating diabetic vasculopathy.

Diabetes and Ischemic Stroke: An Old and New Relationship an Overview of the Close Interaction between These Diseases

Diabetes mellitus is a comprehensive expression to identify a condition of chronic hyperglycemia whose causes derive from different metabolic disorders characterized by altered insulin secretion or faulty insulin effect on its targets or often both mechanisms. Diabetes and atherosclerosis are, from the point of view of cardio- and cerebrovascular risk, two complementary diseases. Beyond shared aspects such as inflammation and oxidative stress, there are multiple molecular mechanisms by which they feed off each other: chronic hyperglycemia and advanced glycosylation end-products (AGE) promote 'accelerated atherosclerosis' through the induction of endothelial damage and cellular dysfunction. These diseases impact the vascular system and, therefore, the risk of developing cardio- and cerebrovascular events is now evident, but the observation of this significant correlation has its roots in past decades. Cerebrovascular complications make diabetic patients 2-6 times more susceptible to a stroke event and this risk is magnified in younger individuals and in patients with hypertension and complications in other vascular beds. In addition, when patients with diabetes and hyperglycemia experience an acute ischemic stroke, they are more likely to die or be severely disabled and less likely to benefit from the one FDA-approved therapy, intravenous tissue plasminogen activator. Experimental stroke models have revealed that chronic hyperglycemia leads to deficits in cerebrovascular structure and function that may explain some of the clinical observations. Increased edema, neovascularization, and protease expression as well as altered vascular reactivity and tone may be involved and point to potential therapeutic targets. Further study is needed to fully understand this complex disease state and the breadth of its manifestation in the cerebrovasculature.

Significance of Inorganic Nitrate Supplement in Cardiovascular Health

BACKGROUND & OBJECTIVES

Nitric Oxide (NO) is frequently produced by the enzyme nitric oxide synthase (NOS) and is crucial for the control and effectiveness of the cardiovascular system. However, there is a substantial reduction in NOS activity with aging that can lead to the development of hypertension and other cardiovascular obstacles. Fortunately, NO can also be produced by sequential reduction of inorganic nitrates supplementation. This proves that NO from inorganic nitrate supplements can compensate for inadequate NOS activity, thus providing cardio protective benefits.

DISCUSSION

This review focuses on the general information about nitrous oxide, its types and mechanism of action and the fact that overview of inadequate NOS activity for cardio protective benefits was often studied for cardiovascular treatments.

CONCLUSION

We concluded that the natural plant NO is essential for cardiovascular activity to target site with desired concentration. Moreover, the researchers focused on evidence that suggested that nitrate supplementation could help regulate blood pressure, limit progression of atherosclerosis, and improve myocardial contractility in both healthy individuals and those with cardiovascular diseases.

Immune cell behaviour and dynamics in the kidney - insights from in vivo imaging

The actions of immune cells within the kidney are of fundamental importance in kidney homeostasis and disease. In disease settings such as acute kidney injury, anti-neutrophil cytoplasmic antibody-associated vasculitis, lupus nephritis and renal transplant rejection, immune cells resident within the kidney and those recruited from the circulation propagate inflammatory responses with deleterious effects on the kidney. As in most forms of inflammation, intravital imaging - particularly two-photon microscopy - has been critical to our understanding of immune cell responses in the renal microvasculature and interstitium, enabling visualization of immune cell dynamics over time rather than statically. These studies have demonstrated differences in the recruitment and function of these cells from those in more conventional vascular beds, and provided a wealth of information on the actions of blood-borne immune cells such as neutrophils, monocytes and T cells, as well as kidney-resident mononuclear phagocytes, in a range of diseases affecting different kidney compartments. In particular, in vivo imaging has furthered our understanding of leukocyte function within the glomerulus in acute glomerulonephritis, and in the tubulointerstitium and interstitial microvasculature during acute kidney injury and following transplantation, revealing mechanisms of immune surveillance, antigen presentation and inflammation in the kidney.

Cells and mediators of inflammation as effectors of epithelial repair in the inflamed intestine

Mucosal and histological healing have become the gold standards for assessing the efficacy of therapy in patients living with inflammatory bowel diseases (IBD). Despite these being the accepted goals in therapy, the mechanisms that underlie the healing of the mucosa after an inflammatory insult are not well understood, and many patients fail to meet this therapeutic endpoint. Here we review the emerging evidence that mediators (e.g., prostaglandins, cytokines, proteases, reactive oxygen, and nitrogen species) and innate immune cells (e.g., neutrophils and monocytes/macrophages), that are involved in the initiation of the inflammatory response, are also key players in the mechanisms underlying mucosal healing to resolve chronic inflammation in the colon. The dual function mediators comprise an inflammation/repair program that returns damaged tissue to homeostasis. Understanding details of the dual mechanisms of these mediators and cells may provide the basis for the development of drugs that can help to stimulate epithelial repair in patients affected by IBD.

Nitric oxide releasing nanomatrix gel treatment inhibits venous intimal hyperplasia and improves vascular remodeling in a rodent arteriovenous fistula

Vascular access is the lifeline for hemodialysis patients and the single most important component of the hemodialysis procedure. Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients, but nearly 60% of AVFs created fail to successfully mature due to early intimal hyperplasia development and poor outward remodeling. There are currently no therapies available to prevent AVF maturation failure. First, we showed the important regulatory role of nitric oxide (NO) on AVF development by demonstrating that intimal hyperplasia development was reduced in an overexpressed endothelial nitric oxide synthase (NOS3) mouse AVF model. This supported the rationale for the potential application of NO to the AVF. Thus, we developed a self-assembled NO releasing nanomatrix gel and applied it perivascularly at the arteriovenous anastomosis immediately following rat AVF creation to investigate its therapeutic effect on AVF development. We demonstrated that the NO releasing nanomatrix gel inhibited intimal hyperplasia formation (more than 70% reduction), as well as improved vascular outward remodeling (increased vein diameter) and hemodynamic adaptation (lower wall shear stress approaching the preoperative level and less vorticity). Therefore, direct application of the NO releasing nanomatrix gel to the AVF anastomosis immediately following AVF creation may enhance AVF development, thereby providing long-term and durable vascular access for hemodialysis.

The Involvement of l-Arginine-Nitric Oxide-cGMP-ATP-Sensitive K+ Channel Pathway in Antinociception of BBHC, a Novel Diarylpentanoid Analogue, in Mice Model

The present study focuses on the possible involvement of l-arginine-nitric oxide-cGMP-ATP-sensitive K⁺ channel pathway in the antinociceptive activity of a novel diarylpentanoid analogue, 2-benzoyl-6-(3-bromo-4-hydroxybenzylidene)cyclohexen-1-ol (BBHC) via a chemical nociceptive model in mice. The antinociceptive action of BBHC (1 mg/kg, i.p.) was attenuated by the intraperitoneal pre-treatment of l-arginine (a nitric oxide synthase precursor) and glibenclamide (an ATP-sensitive K⁺ channel blocker) in acetic acid-induced abdominal constriction tests. Interestingly, BBHC’s antinociception was significantly enhanced by the i.p. pre-treatment of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a selective inhibitor of soluble guanylyl cyclase (p < 0.05). Altogether, these findings suggest that the systemic administration of BBHC is able to establish a significant antinociceptive effect in a mice model of chemically induced pain. BBHC’s antinociception is shown to be mediated by the involvement of l-arginine-nitric oxide-cGMP-ATP-sensitive K⁺ channel pathway, without any potential sedative or muscle relaxant concerns.

Nitric-Oxide-Releasing Dexamethasone Derivative NCX-1005 Improves Lung Function and Attenuates Inflammation in Experimental Lavage-Induced ARDS

Acute respiratory distress syndrome (ARDS) is a common complication of critical illness and remains a major source of morbidity and mortality in the intensive care unit (ICU). ARDS is characterised by diffuse lung inflammation, epithelial and endothelial deterioration, alveolar–capillary leak and oedema formation, and worsening respiratory failure. The present study aimed to investigate the anti-inflammatory activity of nitric-oxide-releasing dexamethasone derivative NCX-1005 as a potential novel drug for ARDS. Adult rabbits with lavage-induced ARDS were treated with dexamethasone i.v. (0.5 mg/kg; DEX) and nitro-dexamethasone i.v. (0.5 mg/kg, NCX-1005) or were untreated (ARDS). Controls represented healthy ventilated animals. The animals were subsequently oxygen-ventilated for an additional 4 h and respiratory parameters were recorded. Lung oedema, inflammatory cell profile in blood and bronchoalveolar lavage, levels of the cytokines (IL-1β, IL-6, IL-8, TNF-α), and oxidative damage (TBARS, 3NT) in the plasma and lung were evaluated. Nitric oxide-releasing dexamethasone derivative NCX-1005 improved lung function, reduced levels of cytokines, oxidative modifications, and lung oedema formation to similar degrees as dexamethasone. Only NCX-1005 prevented the migration of neutrophils into the lungs compared to dexamethasone. In conclusion, the nitric oxide-releasing dexamethasone derivative NCX-1005 has the potential to be effective drug with anti-inflammatory effect in experimental ARDS.

COVID-19 and antiphospholipid antibodies: A position statement and management guidance from AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking (APS ACTION)

Coronavirus disease 2019 (COVID-19) is associated with a high rate of thrombosis. Prolonged activated partial thromboplastin times (aPTT) and antiphospholipid antibodies (aPL) are reported in COVID-19 patients. The majority of publications have not reported whether patients develop clinically relevant persistent aPL, and the clinical significance of new aPL-positivity in COVID-19 is currently unknown. However, the reports of aPL-positivity in COVID-19 raised the question whether common mechanisms exist in the pathogenesis of COVID-19 and antiphospholipid syndrome (APS). In both conditions, thrombotic microangiopathy resulting in microvascular injury and thrombosis is hypothesized to occur through multiple pathways, including endothelial damage, complement activation, and release of neutrophil extracellular traps (NETosis). APS-ACTION, an international APS research network, created a COVID-19 working group that reviewed common mechanisms, positive aPL tests in COVID-19 patients, and implications of COVID-19 infection for patients with known aPL positivity or APS, with the goals of proposing guidance for clinical management and monitoring of aPL-positive COVID-19 patients. This guidance also serves as a call and focus for clinical and basic scientific research.

TNF-α-activated eNOS signaling increases leukocyte adhesion through the S-nitrosylation pathway

Nitric oxide (NO) is a key factor in inflammation. Endothelial nitric oxide synthase (eNOS), whose activity increases after stimulation with proinflammatory cytokines, produces NO in endothelium. NO activates two pathways: 1) soluble guanylate cyclase-protein kinase G and 2) S-nitrosylation (NO-induced modification of free-thiol cysteines in proteins). S-nitrosylation affects phosphorylation, localization, and protein interactions. NO is classically described as a negative regulator of leukocyte adhesion to endothelial cells. However, agonists activating NO production induce a fast leukocyte adhesion, which suggests that NO might positively regulate leukocyte adhesion. We tested the hypothesis that eNOS-induced NO promotes leukocyte adhesion through the S-nitrosylation pathway. We stimulated leukocyte adhesion to endothelium in vitro and in vivo using tumor necrosis factor-α (TNF-α) as proinflammatory agonist. ICAM-1 changes were evaluated by immunofluorescence, subcellular fractionation, immunoprecipitation, and fluorescence recovery after photobleaching (FRAP). Protein kinase Cζ (PKCζ) activity and S-nitrosylation were evaluated by Western blot analysis and biotin switch method, respectively. TNF-α, at short times of stimulation, activated the eNOS S-nitrosylation pathway and caused leukocyte adhesion to endothelial cells in vivo and in vitro. TNF-α-induced NO led to changes in ICAM-1 at the cell surface, which are characteristic of clustering. TNF-α-induced NO also produced S-nitrosylation and phosphorylation of PKCζ, association of PKCζ with ICAM-1, and ICAM-1 phosphorylation. The inhibition of PKCζ blocked leukocyte adhesion induced by TNF-α. Mass spectrometry analysis of purified PKCζ identified cysteine 503 as the only S-nitrosylated residue in the kinase domain of the protein. Our results reveal a new eNOS S-nitrosylation-dependent mechanism that induces leukocyte adhesion and suggests that S-nitrosylation of PKCζ may be an important regulatory step in early leukocyte adhesion in inflammation.NEW & NOTEWORTHY Contrary to the well-established inhibitory role of NO in leukocyte adhesion, we demonstrate a positive role of nitric oxide in this process. We demonstrate that NO induced by eNOS after TNF-α treatment induces early leukocyte adhesion activating the S-nitrosylation pathway. Our data suggest that PKCζ S-nitrosylation may be a key step in this process.

Moving beyond inclusion: Methodological considerations for the menstrual cycle and menopause in research evaluating effects of dietary nitrate on vascular function

Recent reports have acknowledged the underrepresentation of women in the field of dietary nitrate (NO₃^-) research. Undoubtedly, greater participation from women is warranted to clarify potential sex differences in the responses to dietary NO₃^- interventions. However, careful consideration for the effects of sex hormones - principally 17β-estradiol - on endogenous nitric oxide (NO) synthesis and dietary NO₃^- reductase capacity is necessary for improved interpretation and reproducibility of such investigations. From available literature, we present a narrative review describing how hormonal variations across the menstrual cycle, as well as with menopause, may impact NO biosynthesis catalyzed by NO synthase enzymes and NO₃^- reduction via the enterosalivary pathway. In doing so, we address methodological considerations related to the menstrual cycle and hormonal contraceptive use relevant for the inclusion of premenopausal women along with factors to consider when testing postmenopausal women. Adherence to such methodological practices may explicate the utility of dietary NO₃^- supplementation as a means to improve vascular function among women across the lifespan.

Nitric oxide in the Marfan vasculature: Friend or foe?

Marfan syndrome (MFS) is a connective tissue disorder caused by mutations in the FBN1 gene, which encodes fibrillin-1, a protein essential for the formation and stabilization of elastic fibers as well as signaling homeostasis. Progressive aortic root widening is the most serious manifestation of MFS as it can lead to aortic dissection, aneurysm formation and rupture. However, despite their ability to decrease the hemodynamic stress the aorta is subjected to, anti-hypertensive medications often lead to underwhelming reductions in the rate of aortic root dilation, which illustrates how fragmental our understanding of MFS-associated aortic remodeling is. This manuscript summarizes recent evidence that document nitric oxide (NO) synthase (NOS)-related changes to the vasculature during the pathogenesis of MFS and how they result in a unique state of vascular dysfunction that likely plays a causal role in the aortic root widening process. We also review how clinic-approved and experimental therapies as well lifestyle approaches may promote aortic root stability by correcting NO homeostasis, which if properly optimized may improve outcomes in this population afflicted by a notoriously refractory type of aortopathy.

Inflammatory mediators in diabetic retinopathy: Deriving clinicopathological correlations for potential targeted therapy

The role of inflammation in diabetic retinopathy (DR) is well-established and dysregulation of a large number of inflammatory mediators is known. These include cytokines, chemokines, growth factors, mediators of proteogenesis, and pro-apoptotic molecules. This para-inflammation as a response is not directed to a particular pathogen or antigen but is rather directed toward the by-products of the diabetic milieu. The inflammatory mediators take part in cascades that result in cellular level responses like neurodegeneration, pericyte loss, leakage, capillary drop out, neovascularization, etc. There are multiple overlaps between the inflammatory pathways occurring within the diabetic retina due to a large number of mediators, their varied sources, and cross-interactions. This makes understanding the role of inflammation in clinical manifestations of DR difficult. Currently, mediator-based therapy for DR is being evaluated for interventions that target a specific step of the inflammatory cascade. We reviewed the role of inflammation in DR and derived a simplified clinicopathological correlation between the sources and stimuli of inflammation, the inflammatory mediators and pathways, and the clinical manifestations of DR. By doing so, we deliberate mediator-specific therapy for DR. The cross-interactions between inflammatory mediators and the molecular cycles influencing the inflammatory cascades are crucial challenges to such an approach. Future research should be directed to assess the feasibility of the pathology-based therapy for DR.

Predominance of Heart Failure With Preserved Ejection Fraction in Postmenopausal Women: Intra- and Extra-Cardiomyocyte Maladaptive Alterations Scaffolded by Estrogen Deficiency

Heart failure (HF) remains a public health concern as it is associated with high morbidity and death rates. In particular, heart failure with preserved ejection fraction (HFpEF) represents the dominant (>50%) form of HF and mostly occurring among postmenopausal women. Hence, the initiation and progression of the left ventricular diastolic dysfunctions (LVDD) (a typically clinical manifestation of HFpEF) in postmenopausal women have been attributed to estrogen deficiency and the loss of its residue cardioprotective effects. In this review, from a pathophysiological and immunological standpoint, we discuss the probable multiple pathomechanisms resulting in HFpEF, which are facilitated by estrogen deficiency. The initial discussions recap estrogen and estrogen receptors (ERs) and β-adrenergic receptors (βARs) signaling under physiological/pathological states to facilitate cardiac function/dysfunction, respectively. By reconciling these prior discussions, attempts were made to explain how the loss of estrogen facilitates the disruptions both ERs and βARs-mediated signaling responsible for; the modulation of intra-cardiomyocyte calcium homeostasis, maintenance of cardiomyocyte cytoskeletal and extracellular matrix, the adaptive regulation of coronary microvascular endothelial functions and myocardial inflammatory responses. By scaffolding the disruption of these crucial intra- and extra-cardiomyocyte physiological functions, estrogen deficiency has been demonstrated to cause LVDD and increase the incidence of HFpEF in postmenopausal women. Finally, updates on the advancements in treatment interventions for the prevention of HFpEF were highlighted.

Quercetin Completely Ameliorates Hypoxia-Reoxygenation-Induced Pathophysiology Severity in NY1DD Transgenic Sickle Mice: Intrinsic Mild Steady State Pathophysiology of the Disease in NY1DD Is Also Reversed

The vaso-occlusive crisis (VOC) is a major complication of sickle cell disease (SCD); thus, strategies to ameliorate vaso-occlusive episodes are greatly needed. We evaluated the therapeutic benefits of quercetin in a SCD transgenic sickle mouse model. This disease model exhibited very mild disease pathophysiology in the steady state. The severity of the disease in the NY1DD mouse was amplified by subjecting mice to 18 h of hypoxia followed by 3 h of reoxygenation. Quercetin (200 mg/kg body weight) administered to hypoxia challenged NY1DD mice in a single intraperitoneal (i.p.) dose at the onset of reoxygenation completely ameliorated all hypoxia reoxygenation (H/R)-induced pathophysiology. Additionally, it ameliorated the mild intrinsic steady state pathophysiology. These results are comparable with those seen with semisynthetic supra plasma expanders. In control mice, C57BL/6J, hypoxia reoxygenation-induced vaso-occlusion was at significantly lower levels than in NY1DD mice, reflecting the role of sickle hemoglobin (HbS) in inducing vaso-occlusion; however, the therapeutic benefits from quercetin were significantly muted. We suggest that these findings represent a unique genotype of the NY1DD mice, i.e., the presence of high oxygen affinity red blood cells (RBCs) with chimeric HbS, composed of mouse α-chain and human β^S-chain, as well as human α-chain and mouse β-chain (besides HbS). The anti-anemia therapeutic benefits from high oxygen affinity RBCs in these mice exert disease severity modifications that synergize with the therapeutic benefits of quercetin. Combining the therapeutic benefits of high oxygen affinity RBCs generated in situ by chemical or genetic manipulation with the therapeutic benefits of antiadhesive therapies is a novel approach to treat sickle cell patients with severe pathophysiology.

Inhalational Gases for Neuroprotection in Traumatic Brain Injury

Despite multiple prior pharmacological trials in traumatic brain injury (TBI), the search for an effective, safe, and practical treatment of these patients remains ongoing. Given the ease of delivery and rapid absorption into the systemic circulation, inhalational gases that have neuroprotective properties will be an invaluable resource in the clinical management of TBI patients. In this review, we perform a systematic review of both pre-clinical and clinical reports describing inhalational gas therapy in the setting of TBI. Hyperbaric oxygen, which has been investigated for many years, and some of the newest developments are reviewed. Also, promising new therapies such as hydrogen gas, hydrogen sulfide gas, and nitric oxide are discussed. Moreover, novel therapies such as xenon and argon gases and delivery methods using microbubbles are explored.

Metabolic Adjustments by LncRNAs in Peripheral Neutrophils Partly Account for the Complete Compensation of Asymptomatic MMD Patients

BACKGROUND

Due to the recent development of non-invasive examinations, more asymptomatic patients with Moyamoya Disease (MMD) have been diagnosed than ever. However, its underlying molecular mechanisms and clinical intervention guidelines are all still obscure.

METHODS

Microarray was used to explore those differentially expressed mRNAs and lncRNAs in peripheral neutrophils of asymptomatic MMD patients. Then enrichment analyses based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) for those differentially expressed mRNAs and lncRNA associated mRNAs were performed for underlying molecular mechanisms.

RESULTS

Here, we identified a total of 2824 differentially expressed lncRNAs and 522 differentially expressed mRNAs (fold change > 2 and P<0.05) in peripheral neutrophils of asymptomatic MMD patients, compared with healthy controls. Then enrichment analyses based on GO and KEGG showed that the neighboring protein-coding mRNAs of those up-regulated and down-regulated lncRNAs were mainly involved in distinct metabolic processes respectively, which may act as a complementary response to insufficient blood supplies in MMD. Further enrichment analyses of those differentially expressed mRNAs preferentially listed essential physiological processes such as peptide cross-linking, chromatin assembly among others. Moreover, altered mRNAs also revealed to be enriched in renin secretion, platelet activation, inflammation and others.

CONCLUSION

We demonstrated for the first time that metabolic adjustments by dysregulated lncRNAs in peripheral neutrophils might partially account for the complete compensation of asymptomatic MMD patients. In addition, more attention should be paid on renin secretion and platelet activation in order to better understand the pathogenesis and guide clinical intervention for asymptomatic MMDs.

Brain vulnerability and viability after ischaemia

The susceptibility of the brain to ischaemic injury dramatically limits its viability following interruptions in blood flow. However, data from studies of dissociated cells, tissue specimens, isolated organs and whole bodies have brought into question the temporal limits within which the brain is capable of tolerating prolonged circulatory arrest. This Review assesses cell type-specific mechanisms of global cerebral ischaemia, and examines the circumstances in which the brain exhibits heightened resilience to injury. We suggest strategies for expanding such discoveries to fuel translational research into novel cytoprotective therapies, and describe emerging technologies and experimental concepts. By doing so, we propose a new multimodal framework to investigate brain resuscitation following extended periods of circulatory arrest.

Histological assessment of the local effect of different concentrations of aminoguanidine hydrochloride on bone healing in rats

BACKGROUND

Nitric oxide (NO) has several functions in bone healing and affects bone metabolism. Selective inducible NO synthase (iNOS) inhibitors can be used to assess the efficacy of NO for healing of bone defects. This study sought to assess the local effect of different concentrations of aminoguanidine hydrochloride (AG), a selective iNOS inhibitor, on bone healing in rats.

MATERIALS AND METHODS

In this animal experimental study, 72 rats were divided into six groups of control, placebo, 5% AG, 10% AG, 15% AG, and 20% AG. A bone defect measuring 5 mm × 5 mm was created in the femur. The defect remained empty in the control group. In the placebo group, neutral gel was placed in the bone defect, and in the remaining four AG groups, different concentrations of AG were applied to the defects. Bone healing was assessed histologically. The healing score in the six groups was analyzed by the Kruskal-Wallis test. A P < 0.05 was considered statistically significant.

RESULTS

The healing score in 20%, 15%, 10%, and 5% AG groups was significantly higher than that in the neutral gel and control groups (P < 0.01). Among the four groups of AG, 20% concentration showed better results, but the difference was not significant.

CONCLUSION

Four concentrations of AG caused greater bone healing compared to the other two groups. Selective iNOS inhibitors such as AG can be used to promote local bone healing.

Pathophysiology of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: A Review

Delayed cerebral ischemia is a major predictor of poor outcomes in patients who suffer subarachnoid hemorrhage. Treatment options are limited and often ineffective despite many years of investigation and clinical trials. Modern advances in basic science have produced a much more complex, multifactorial framework in which delayed cerebral ischemia is better understood and novel treatments can be developed. Leveraging this knowledge to improve outcomes, however, depends on a holistic understanding of the disease process. We conducted a review of the literature to analyze the current state of investigation into delayed cerebral ischemia with emphasis on the major themes that have emerged over the past decades. Specifically, we discuss microcirculatory dysfunction, glymphatic impairment, inflammation, and neuroelectric disruption as pathological factors in addition to the canonical focus on cerebral vasospasm. This review intends to give clinicians and researchers a summary of the foundations of delayed cerebral ischemia pathophysiology while also underscoring the interactions and interdependencies between pathological factors. Through this overview, we also highlight the advances in translational studies and potential future therapeutic opportunities.

Clinical assessment of endothelial function in heart failure with preserved ejection fraction: A meta-analysis with meta-regressions

BACKGROUND

Endothelial dysfunction is a key mechanism in the development of cardiac remodelling and diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF). Flow-mediated (FMD) and nitrate-mediated dilation (NMD) are noninvasive methods to assess endothelial function. We performed a meta-analysis evaluating the impact of HFpEF on FMD and NMD.

METHODS

PubMed, Web of Science, Scopus and EMBASE databases were systematically searched according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Differences were expressed as mean difference (MD) with 95% confidence intervals (95%CI). The random effects method was used.

RESULTS

A total of seven studies were included in the final analysis, 7 with data on FMD (326 HFpEF patients and 417 controls) and 3 on NMD (185 HFpEF patients and 271 controls). Compared to controls, HFpEF patients showed significantly lower FMD (MD: -1.929; 95%CI: -2.770, -1.088; P < .0001) and NMD values (MD: -2.795; 95%CI: -3.876, -1.715; P < .0001). Sensitivity analyses substantially confirmed results. Meta-regression models showed that increasing differences in E/A ratio (Z-score: -2.002; P = .045), E/E' ratio (Z-score: -2.181; P = .029) and left atrial diameter (Z-score: -1.951; P = .050) were linked to higher differences in FMD values between cases and controls.

CONCLUSIONS

Impaired endothelial function can be documented in HFpEF, with the possibility of a direct association between the severity of diastolic and endothelial dysfunction. Targeting endothelial dysfunction through pharmacological and rehabilitation strategies may represent an attractive therapeutic option.

Anti-angiogenic agents - overcoming tumour endothelial cell anergy and improving immunotherapy outcomes

Immune checkpoint inhibitors have revolutionized medical oncology, although currently only a subset of patients has a response to such treatment. A compelling body of evidence indicates that anti-angiogenic therapy has the capacity to ameliorate antitumour immunity owing to the inhibition of various immunosuppressive features of angiogenesis. Hence, combinations of anti-angiogenic agents and immunotherapy are currently being tested in >90 clinical trials and 5 such combinations have been approved by the FDA in the past few years. In this Perspective, we describe how the angiogenesis-induced endothelial immune cell barrier hampers antitumour immunity and the role of endothelial cell anergy as the vascular counterpart of immune checkpoints. We review the antitumour immunity-promoting effects of anti-angiogenic agents and provide an update on the current clinical successes achieved when these agents are combined with immune checkpoint inhibitors. Finally, we propose that anti-angiogenic agents are immunotherapies - and vice versa - and discuss future research priorities.

Non-functioning adrenal incidentalomas may increase toxic metabolites

BACKGROUND

Non-functioning adrenal incidentaloma (NFAI) is a frequent diagnosis with increasing radiological tests. The emerging shreds of evidence showed that they might have negative cardiometabolic effects. The study aimed to investigate whether the toxic metabolites, asymmetric dimethylarginine (ADMA) levels, were altered in NFAI patients.

METHODS

We included 43 NFAI patients and 41 controls with similar ages and body mass indices in the study. We compared plasma ADMA levels of both groups and noted the radiological features of NFAIs.

RESULTS

The ADMA levels were significantly higher in NFAI patients than in the control group (307.04 ng/ml, range 81.89-577.7 ng/ml vs 192.54 ng/ml, range 70.61-440.26 ng/ml, p = 0.001). Nevertheless, we could not reach a significant correlation between ADMA levels and mass size.

CONCLUSION

The ADMA is known as a toxin and is increased in NFAI patients. NFAIs may not be innocent and may be considered a potential risk for the body. Further investigations were needed for more explanations.

[Modulation of endothelial factors activity in human endothelial cells in influenza A(H1N1)pdm09 virus infection]

INTRODUCTION

Influenza A virus infection can lead to endothelial dysfunction (ED), including apoptosis of endothelial cells and modulation of endothelial factor activities. Affected biochemical factors may include those playing important roles in vascular homeostasis. However, the effect of this pathogen on the expression pattern of key endothelial factors is still unknown.The aim of this work was to study the expression of endothelial nitric oxide synthase (eNOS) and plasminogen activator inhibitor-1 (PAI-1, serpin E1) in the EA.hy926 endothelial cells.

RESEARCH OBJECTIVES

to assess expression of eNOS and PAI-1 in endothelial cells infected with influenza virus A(H1N1)pdm09, and to identify homologous fragments in structure of viral proteins and endothelial factors.

MATERIAL AND METHODS

Cells were infected with influenza virus A/St. Petersburg/48/16 (H1N1)pdm09 and analyzed in dynamics in 6, 12, 18, 24, 48, and 72 hrs post infection (hpi). Detection of endothelial factors expression levels was performed by immunocytochemical method (ICC) using antibodies for eNOS and PAI-1 while quantitative assessment of expression levels was carried out by program Nis-Elements F3.2 («Nikon», Japan). The search for homologous sequences between viral proteins and eNOS and PAI-1 was performed by computer comparison. Sequences were analyzed as fragments 12 amino acid residues (aar) in length.

RESULTS AND DISCUSSION

eNOS expression in infected cells had decreased to 7.9% by 6 hpi (control was taken as 100%) to 3.3% at 72 hpi. PAI-1 expression varied significantly over the course of the experiment: by 6 hpi it had decreased to 49.6%, and to 43.2% by 12 hpi. Later PAI-1 levels were: 116.3% (18 hpi); 18.9% (24 hpi); 23.5% (48 hpi), and 35% (72 hpi).

CONCLUSION

These results indicate that influenza A infection of endothelial cells causes a significant decrease in eNOS expression, while modulating PAI-1 one. The described phenomenon can be used in the further development of directions of pathogenetic therapy of vascular complications of infection caused by this pathogen.

Study on the Mechanism of the Danggui-Chuanxiong Herb Pair on Treating Thrombus through Network Pharmacology and Zebrafish Models

Danggui-Chuanxiong (DC) is a commonly used nourishing and activating blood medicine pair in many gynecological prescriptions and modern Chinese medicine. However, its activating blood mechanism has not been clearly elucidated. Our research aimed at investigating the activating blood mechanisms of DC using network pharmacology and zebrafish experiments. Network pharmacology was used to excavate the potential targets and mechanisms of DC in treating thrombus. The antithrombotic, anti-inflammatory, antioxidant, and vasculogenesis activities of DC and the main components of DC, ferulic acid (DC2), ligustilide (DC7), and levistilide A (DC17), were evaluated by zebrafish models in vivo. A total of 24 compounds were selected as the active ingredients with favorable pharmacological parameters for this herb pair. A total of 89 targets and 18 pathways related to the thrombus process were gathered for active compounds. The genes, TNF, CXCR4, IL2, ESR1, FGF2, HIF1A, CXCL8, AR, FOS, MMP2, MMP9, STAT3, and RHOA, might be the main targets for this herb pair to exert cardiovascular activity from the analysis of protein-protein interaction and KEGG pathway results, which were mainly related to inflammation, vasculogenesis, immunity, hormones, and so forth. The zebrafish experiment results showed that DC had antithrombotic, anti-inflammatory, antioxidant, and vasculogenesis activities. The main compounds had different effects of zebrafish activities. Especially, the antithrombotic activity of the DC17H group, anti-inflammatory activities of DCH and DC2H groups, antioxidant activities of DCM, DCH, DC2, DC7, and DC17 groups, and vasculogenesis activities of DCM, DCH, and DC2 groups were stronger than those of the positive group. The integrated method coupled zebrafish models with network pharmacology provided the insights into the mechanisms of DC in treating thrombus.

Retinal toxicities of systemic anticancer drugs

Newer anticancer drugs have revolutionized cancer treatment in the last decade, but conventional chemotherapy still occupies a central position in many cancers, with combination therapy and newer methods of delivery increasing their efficacy while minimizing toxicities. We discuss the retinal toxicities of anticancer drugs with an emphasis on the mechanism of toxicity. Uveitis is seen with the use of v-raf murine sarcoma viral oncogene homolog B editing anticancer inhibitors as well as immunotherapy. Most of the cases are mild with only anterior uveitis, but severe cases of posterior uveitis, panuveitis, and Vogt-Koyanagi-Harada-like disease may also occur. In the retina, a transient neurosensory detachment is observed in almost all patients on mitogen-activated protein kinase kinase (MEK) inhibitors. Microvasculopathy is often seen with interferon α, but vascular occlusion is a more serious toxicity caused by interferon α and MEK inhibitors. Crystalline retinopathy with or without macular edema may occur with tamoxifen; however, even asymptomatic patients may develop cavitatory spaces seen on optical coherence tomography. A unique macular edema with angiographic silence is characteristic of taxanes. Delayed dark adaptation has been observed with fenretinide. Interestingly, this drug is finding potential application in Stargardt disease and age-related macular degeneration.

The Molecular Basis of COVID-19 Pathogenesis, Conventional and Nanomedicine Therapy

In late 2019, a new member of the Coronaviridae family, officially designated as "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2), emerged and spread rapidly. The Coronavirus Disease-19 (COVID-19) outbreak was accompanied by a high rate of morbidity and mortality worldwide and was declared a pandemic by the World Health Organization in March 2020. Within the Coronaviridae family, SARS-CoV-2 is considered to be the third most highly pathogenic virus that infects humans, following the severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV). Four major mechanisms are thought to be involved in COVID-19 pathogenesis, including the activation of the renin-angiotensin system (RAS) signaling pathway, oxidative stress and cell death, cytokine storm, and endothelial dysfunction. Following virus entry and RAS activation, acute respiratory distress syndrome develops with an oxidative/nitrosative burst. The DNA damage induced by oxidative stress activates poly ADP-ribose polymerase-1 (PARP-1), viral macrodomain of non-structural protein 3, poly (ADP-ribose) glycohydrolase (PARG), and transient receptor potential melastatin type 2 (TRPM2) channel in a sequential manner which results in cell apoptosis or necrosis. In this review, blockers of angiotensin II receptor and/or PARP, PARG, and TRPM2, including vitamin D3, trehalose, tannins, flufenamic and mefenamic acid, and losartan, have been investigated for inhibiting RAS activation and quenching oxidative burst. Moreover, the application of organic and inorganic nanoparticles, including liposomes, dendrimers, quantum dots, and iron oxides, as therapeutic agents for SARS-CoV-2 were fully reviewed. In the present review, the clinical manifestations of COVID-19 are explained by focusing on molecular mechanisms. Potential therapeutic targets, including the RAS signaling pathway, PARP, PARG, and TRPM2, are also discussed in depth.

3D-Printed, Modular, and Parallelized Microfluidic System with Customizable Scaffold Integration to Investigate the Roles of Basement Membrane Topography on Endothelial Cells

Because dysfunctions of endothelial cells are involved in many pathologies, in vitro endothelial cell models for pathophysiological and pharmaceutical studies have been a valuable research tool. Although numerous microfluidic-based endothelial models have been reported, they had the cells cultured on a flat surface without considering the possible three-dimensional (3D) structure of the native extracellular matrix (ECM). Endothelial cells rest on the basement membrane in vivo, which contains an aligned microfibrous topography. To better understand and model the cells, it is necessary to know if and how the fibrous topography can affect endothelial functions. With conventional fully integrated microfluidic apparatus, it is difficult to include additional topographies in a microchannel. Therefore, we developed a modular microfluidic system by 3D-printing and electrospinning, which enabled easy integration and switching of desired ECM topographies. Also, with standardized designs, the system allowed for high flow rates up to 4000 μL/min, which encompassed the full shear stress range for endothelial studies. We found that the aligned fibrous topography on the ECM altered arginine metabolism in endothelial cells and thus increased nitric oxide production. There has not been an endothelial model like this, and the new knowledge generated thereby lays a groundwork for future endothelial research and modeling.

Cardiovascular Responses During Sepsis

Sepsis is the life-threatening organ dysfunction arising from a dysregulated host response to infection. Although the specific mechanisms leading to organ dysfunction are still debated, impaired tissue oxygenation appears to play a major role, and concomitant hemodynamic alterations are invariably present. The hemodynamic phenotype of affected individuals is highly variable for reasons that have been partially elucidated. Indeed, each patient's circulatory condition is shaped by the complex interplay between the medical history, the volemic status, the interval from disease onset, the pathogen, the site of infection, and the attempted resuscitation. Moreover, the same hemodynamic pattern can be generated by different combinations of various pathophysiological processes, so the presence of a given hemodynamic pattern cannot be directly related to a unique cluster of alterations. Research based on endotoxin administration to healthy volunteers and animal models compensate, to an extent, for the scarcity of clinical studies on the evolution of sepsis hemodynamics. Their results, however, cannot be directly extrapolated to the clinical setting, due to fundamental differences between the septic patient, the healthy volunteer, and the experimental model. Numerous microcirculatory derangements might exist in the septic host, even in the presence of a preserved macrocirculation. This dissociation between the macro- and the microcirculation might account for the limited success of therapeutic interventions targeting typical hemodynamic parameters, such as arterial and cardiac filling pressures, and cardiac output. Finally, physiological studies point to an early contribution of cardiac dysfunction to the septic phenotype, however, our defective diagnostic tools preclude its clinical recognition. © 2021 American Physiological Society. Compr Physiol 11:1605-1652, 2021.

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

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

Higher susceptibility to heme oxidation and lower protein stability of the rare α1C517Yβ1 sGC variant associated with moyamoya syndrome

NO sensitive soluble guanylyl cyclase (sGC) plays a key role in mediating physiological functions of NO. Genetic alterations of the GUCY1A3 gene, coding for the α1 subunit of sGC, are associated with several cardiovascular dysfunctions. A rare sGC variant with Cys517 → Tyr substitution in the α1subunit, has been associated with moyamoya disease and achalasia. In this report we characterize the properties of this rare sGC variant. Purified α1C517Yβ1 sGC preserved only ~25% of its cGMP-forming activity and showed an elevated Km for GTP substrate. However, the mutant enzyme retained a high affinity for and robust activation by NO, similar to wild type sGC. Purified α1C517Yβ1 enzyme was more sensitive to specific sGC heme oxidizers and less responsive to heme reducing agents. When expressed in COS7 cells, α1C517Yβ1 sGC showed a much stronger response to cinaciguat or gemfibrozil, which targets apo-sGC or sGC with ferric heme, as compared to its NO response or the relative response of the wild type sGC. A stronger response to cinaciguat was also observed for purified α1C517Yβ1 in the absence of reducing agents. In COS7 cells, αCys517β sGC was less stable than the wild type enzyme under normal conditions and exhibited accelerated degradation upon induction of cellular oxidative stress. We conclude that diminished cGMP-forming activity of this sGC variant is aggravated by its high susceptibility to oxidative stress and diminished protein stability. The combination of these deficiencies contributes to the severity of observed moyamoya and achalasia symptoms in human carriers of this rare α1C517Yβ1 sGC variant.

Epidemiology, Pathophysiology, Diagnosis and Treatment of Heart Failure in Diabetes

The cardiovascular disease continuum begins with risk factors such as diabetes mellitus (DM), progresses to vasculopathy and myocardial dysfunction, and finally ends with cardiovascular death. Diabetes is associated with a 2- to 4-fold increased risk for heart failure (HF). Moreover, HF patients with DM have a worse prognosis than those without DM. Diabetes can cause myocardial ischemia via micro- and macrovasculopathy and can directly exert deleterious effects on the myocardium. Hyperglycemia, hyperinsulinemia, and insulin resistance can cause alterations in vascular homeostasis. Then, reduced nitric oxide and increased reactive oxygen species levels favor inflammation leading to atherothrombotic progression and myocardial dysfunction. The classification, diagnosis, and treatment of HF for a patient with and without DM remain the same. Until now, drugs targeting neurohumoral and metabolic pathways improved mortality and morbidity in HF with reduced ejection fraction (HFrEF). Therefore, all HFrEF patients should receive guideline-directed medical therapy. By contrast, drugs modulating neurohumoral activity did not improve survival in HF with preserved ejection fraction (HFpEF) patients. Trials investigating whether sodium-glucose cotransporter-2 inhibitors are effective in HFpEF are on-going. This review will summarize the epidemiology, pathophysiology, and treatment of HF in diabetes.

Nitric Oxide Synthase Inhibitors into the Clinic at Last

The 1998 Nobel Prize in Medicine and Physiology for the discovery of nitric oxide, a nitrogen containing reactive oxygen species (also termed reactive nitrogen or reactive nitrogen/oxygen species) stirred great hopes. Clinical applications, however, have so far pertained exclusively to the downstream signaling of cGMP enhancing drugs such as phosphodiesterase inhibitors and soluble guanylate cyclase stimulators. All clinical attempts, so far, to inhibit NOS have failed even though preclinical models were strikingly positive and clinical biomarkers correlated perfectly. This rather casts doubt on our current way of target identification in drug discovery in general and our way of patient stratification based on correlating but not causal biomarkers or symptoms. The opposite, NO donors, nitrite and enhancing NO synthesis by eNOS/NOS3 recoupling in situations of NO deficiency, are rapidly declining in clinical relevance or hold promise but need yet to enter formal therapeutic guidelines, respectively. Nevertheless, NOS inhibition in situations of NO overproduction often jointly with enhanced superoxide (or hydrogen peroxide production) still holds promise, but most likely only in acute conditions such as neurotrauma (Stover et al., J Neurotrauma 31(19):1599-1606, 2014) and stroke (Kleinschnitz et al., J Cereb Blood Flow Metab 1508-1512, 2016; Casas et al., Proc Natl Acad Sci U S A 116(14):7129-7136, 2019). Conversely, in chronic conditions, long-term inhibition of NOS might be too risky because of off-target effects on eNOS/NOS3 in particular for patients with cardiovascular risks or metabolic and renal diseases. Nitric oxide synthases (NOS) and their role in health (green) and disease (red). Only neuronal/type 1 NOS (NOS1) has a high degree of clinical validation and is in late stage development for traumatic brain injury, followed by a phase II safety/efficacy trial in ischemic stroke. The pathophysiology of NOS1 (Kleinschnitz et al., J Cereb Blood Flow Metab 1508-1512, 2016) is likely to be related to parallel superoxide or hydrogen peroxide formation (Kleinschnitz et al., J Cereb Blood Flow Metab 1508-1512, 2016; Casas et al., Proc Natl Acad Sci U S A 114(46):12315-12320, 2017; Casas et al., Proc Natl Acad Sci U S A 116(14):7129-7136, 2019) leading to peroxynitrite and protein nitration, etc. Endothelial/type 3 NOS (NOS3) is considered protective only and its inhibition should be avoided. The preclinical evidence for a role of high-output inducible/type 2 NOS (NOS2) isoform in sepsis, asthma, rheumatic arthritis, etc. was high, but all clinical development trials in these indications were neutral despite target engagement being validated. This casts doubt on the role of NOS2 in humans in health and disease (hence the neutral, black coloring).

Clinical application of nitric oxide in ischemia and reperfusion injury: A literature review

Ischemia–reperfusion injury (IRI) is a series of multifactorial cellular events that lead to increased cellular dysfunction after the restoration of oxygen delivery to hypoxic tissue, which can result in acute heart failure and cerebral dysfunction. This injury is severe and would lead to significant morbidity and mortality and poses an important therapeutic challenge for physicians. Nitric oxide (NO) minimizes the deleterious effects of IRI on cells. NO donors, such as organic nitrates and sodium nitroprusside, are used systematically to treat heart failure, angina, and pulmonary hypertension. Inhaled NO gas was approved by the FDA in 1999 to treat hypoxic newborns, and its beneficial ameliorations reach outside the realm of lung disease. This review will summarize the clinical application of NO in IRI.

Inhaled Gases as Therapies for Post-Cardiac Arrest Syndrome: A Narrative Review of Recent Developments

Despite recent advances in the management of post-cardiac arrest syndrome (PCAS), the survival rate, without neurologic sequelae after resuscitation, remains very low. Whole-body ischemia, followed by reperfusion after cardiac arrest (CA), contributes to PCAS, for which established pharmaceutical interventions are still lacking. It has been shown that a number of different processes can ultimately lead to neuronal injury and cell death in the pathology of PCAS, including vasoconstriction, protein modification, impaired mitochondrial respiration, cell death signaling, inflammation, and excessive oxidative stress. Recently, the pathophysiological effects of inhaled gases including nitric oxide (NO), molecular hydrogen (H₂), and xenon (Xe) have attracted much attention. Herein, we summarize recent literature on the application of NO, H₂, and Xe for treating PCAS. Recent basic and clinical research has shown that these gases have cytoprotective effects against PCAS. Nevertheless, there are likely differences in the mechanisms by which these gases modulate reperfusion injury after CA. Further preclinical and clinical studies examining the combinations of standard post-CA care and inhaled gas treatment to prevent ischemia-reperfusion injury are warranted to improve outcomes in patients who are being failed by our current therapies.

Nitric Oxide in Post-cardiac Arrest Syndrome

Sudden cardiac arrest is a leading cause of death worldwide. Although the methods of cardiopulmonary resuscitation have been improved, mortality is still unacceptably high, and many survivors suffer from lasting neurological deficits due to the post-cardiac arrest syndrome (PCAS). Pathophysiologically, generalized vascular endothelial dysfunction accompanied by platelet activation and systemic inflammation has been implicated in the pathogenesis of PCAS. Because endothelial-derived nitric oxide (NO) plays a central role in maintaining vascular homeostasis, the role of NO-dependent signaling has been a focus of the intense investigation. Recent preclinical studies showed that therapeutic interventions that increase vascular NO bioavailability may improve outcomes after cardiac arrest complicated with PCAS. In particular, NO inhalation therapy has been shown to improve neurological outcomes and survival in multiple species. Clinical studies examining the safety and efficacy of inhaled NO in patients sustaining PCAS are warranted.

Statins as an adjunctive therapy for COVID-19: the biological and clinical plausibility

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the coronavirus disease 2019 (COVID-19) has infected millions of individuals and has claimed hundreds of thousands of human lives worldwide. Patients with underlying cardiovascular conditions are at high risk for SARS-CoV-2 infection, and COVID-19 patients have high incidence of cardiovascular complications such as acute cardiac injury, arrhythmias, heart failure, and thromboembolism. The disease has no approved proven effective therapy and hence repurposing of existing approved drugs has been considered as the fastest treatment approach. Statins have been shown to exhibit lipid lowering dependent and independent cardiovascular protective effects as well as favorable effects in various other pathophysiological states. These beneficial properties of statins are a result of their multiple pleotropic effects that include, anti-inflammatory, immunomodulatory, antithrombotic and antimicrobial properties. In this review, we provide a comprehensive description of the mechanisms of the pleotropic effects of statins, the relevant pre-clinical and clinical data pertinent to their role in infections and acute lung injury, the possible cardiovascular benefits of statins in COVID-19, and the implications of the therapeutic potential of statins in COVID-19 disease. We conclude with the rationale for conducting randomized controlled trials of statins in COVID-19 disease.

Assessment of potential cardiovascular risk in trichloroethylene exposure by serum methylated arginine levels

Trichloroethylene (TCE) is a widely used solvent in industrial applications and has toxic effects on various systems. Methylated arginine amino acids (eg asymmetric dimethyl arginine (ADMA), symmetric dimethyl arginine (SDMA)) cause the development of cardiovascular disease by inhibiting NO synthesis, which is considered to be heart-protector. The aim of this study is to determine the risk of cardiovascular diseases in TCE exposure by methylated arginine biomarkers. About 98 controls and 100 TCE-exposed male subjects were included in the study. Trichloroacetic acid (urinary metabolite of TCE), arginine, homoarginine, citrulline ADMA, SDMA, and N-monomethyl L-arginine (L-NMMA) levels were found significantly higher than control group (p < 0.001). The strongest correlation was found between ADMA and Trichloroacetic acid (TCA) level (r = 0.453, p < 0.01). Long-term TCE exposure, may be an important risk factor for cardiovascular diseases by increasing methylated arginine levels.

The role of nitric oxide in peptic ulcer: a narrative review

Peptic ulcer refers to the inflammatory response and necrotic lesions of the mucosa under the action of various pathogenic factors, which goes deeply into the mucosal muscle layer and often occurs to the gastrointestinal mucosa related to gastric acid secretion, among which the stomach and duodenum are the most common. The clinical manifestations include slow onset, prolonged course and weekly upper abdominal pain. Nitric oxide (NO) is an intracellular and intercellular signaling molecule that plays an important role in many physiological and pathological processes. Studies have found that a small amount of NO produced in vivo plays a role in many physiological homeostasis, such as regulating blood pressure, platelet aggregation, nitrogenization of hemoglobin, and regulating proliferation and differentiation of stem cells. However, under the action of some cytokines and oxidative stress, intracellular NO synthase will catalyze the synthesis of large amounts of NO and participate in the inflammatory response, causing beneficial or harmful effect on the body. Numerous basic studies have focused on the relationship between NO and peptic ulcer. The purpose of this review is to summarize the role of NO in peptic ulcer and its possible mechanism.