Superoxide generation by endothelial nitric oxide synthase: the influence of cofactors

Fructooligosaccharides reverses hepatic vascular dysfunction and dysbiosis in rats with liver cirrhosis and portal hypertension

BACKGROUND

Portal hypertension leads to lethal complications in liver cirrhosis. Oxidative stress induced hepatic vascular dysfunction, which exaggerated vasoconstriction and increases hepatic vascular resistance (HVR). Gut dysbiosis further exacerbates portal hypertension. Fructooligosaccharides are prebiotics with potent antioxidant effect. This study aimed to evaluate the roles of fructooligosaccharides in portal hypertension-related vascular dysregulation and gut microbiome.

METHODS

Sprague-Dawley rats received bile duct ligation to induce cirrhosis or sham operation as controls. The rats then randomly received fructooligosaccharides or vehicle for 4 weeks. Experiments were performed on the 29th day after operations.

RESULTS

Fructooligosaccharides did not affect portal pressure. Interestingly, fructooligosaccharides significantly attenuated HVR (p = .03). Malondialdehyde, an oxidative stress marker, reduced significantly in the liver in fructooligosaccharides-treated group. In addition, superoxide dismutase and trolox equivalent antioxidant capacity increased in the treatment group. On the other hand, vasodilatation-related protein expressions, GTPCH and phospho-eNOS, enhanced significantly. Fructooligosaccharides had no adverse vasodilatation effects on splanchnic vascular system or porto-systemic collateral systems. Locomotor function was not affected by fructooligosaccharides. Faecal microbiota analysis showed that Negativicutes, Selenomonadales and Lactobacillus salivarius reduced in the fructooligosaccharides-treated group.

CONCLUSION

In conclusion, fructooligosaccharides attenuate hepatic vascular dysfunction in cirrhotic rats via at least partly, ameliorate of dysbiosis and oxidative stress.

Sodium nitrite induces tolerance in the mouse aorta: Involvement of the renin-angiotensin system, nitric oxide synthase, and reactive oxygen species

Nitrites have emerged as promising therapeutic agents for cardiovascular diseases, alongside nitrates. While chronic use of organic nitrates is well recognized to lead to vascular tolerance, the tolerance associated with nitrite therapy remains incompletely understood. The aim of the present study was to investigate vascular tolerance to sodium nitrite and the underlying molecular mechanisms. Endothelium-denuded aortic rings isolated from male Balb/C mice were incubated with either the EC50 (10-4 mol/L) or EC100 (10-2 mol/L) concentration of sodium nitrite for 15 min to induce tolerance. The EC100 concentration of sodium nitrite induced vascular tolerance. Pre-incubation with captopril and losartan effectively reversed sodium nitrite-induced tolerance. Similarly, pre-incubation with L-NAME and L-arginine prevented sodium nitrite-induced tolerance. Increased levels of reactive oxidative species (ROS) and reduced bioavailability of nitric oxide (NO) were observed in tolerant aortas. Increased superoxide dismutase (SOD) activity and decreased catalase activity were also verified in tolerant aortas. Both captopril and L-NAME prevented the increased levels of ROS observed in tolerant aortas. Furthermore, pre-incubation with catalase effectively prevented sodium nitrite-induced tolerance. Our findings suggest that sodium nitrite induces vascular tolerance through a signaling pathway involving the renin-angiotensin system, nitric oxide synthase, and ROS. This study contributes to the understanding of the interaction between nitrites and vascular tolerance and highlights potential targets to overcome or prevent this phenomenon.

Inhibition of Sirtuin Deacylase Activity by Peroxynitrite

Sirtuins are a class of enzymes that deacylate protein lysine residues using NAD+ as a cosubstrate. Sirtuin deacylase activity has been historically regarded as protective; loss of sirtuin deacylase activity potentially increases susceptibility to aging-related disease development. However, which factors may inhibit sirtuins during aging or disease is largely unknown. Increased oxidant and inflammatory byproduct production damages cellular proteins. Previously, we and others found that sirtuin deacylase activity is inhibited by the nitric oxide (NO)-derived cysteine post-translational modification S-nitrosation. However, the comparative ability of the NO-derived oxidant peroxynitrite (ONOO-) to affect human sirtuin activity had not yet been assessed under uniform conditions. Here, we compare the ability of ONOO- (donated from SIN-1) to post-translationally modify and inhibit SIRT1, SIRT2, SIRT3, SIRT5, and SIRT6 deacylase activity. In response to SIN-1 treatment, inhibition of SIRT1, SIRT2, SIRT3, SIRT5, and SIRT6 deacylase activity correlated with increased tyrosine nitration. Mass spectrometry identified multiple novel tyrosine nitration sites in SIRT1, SIRT3, SIRT5, and SIRT6. As each sirtuin isoform has at least one tyrosine nitration site within the catalytic core, nitration may result in sirtuin inhibition. ONOO- can also react with cysteine residues, resulting in sulfenylation; however, only SIRT1 showed detectable peroxynitrite-mediated cysteine sulfenylation. While SIRT2, SIRT3, SIRT5, and SIRT6 showed no detectable sulfenylation, SIRT6 likely undergoes transient sulfenylation, quickly resolving into an intermolecular disulfide bond. These results suggest that the aging-related oxidant peroxynitrite can post-translationally modify and inhibit sirtuins, contributing to susceptibility to aging-related disease.

Endothelial Reactive Oxygen Species: Key Players in Cardiovascular Health and Disease

Significance: Endothelial cells (ECs) line the entire vasculature system and serve as both barriers and facilitators of intra- and interorgan communication. Positioned to rapidly sense internal and external stressors, ECs dynamically adjust their functionality. Endothelial dysfunction occurs when the ability of ECs to react to stressors is impaired, which precedes many cardiovascular diseases (CVDs). While EC reactive oxygen species (ROS) have historically been implicated as mediators of endothelial dysfunction, more recent studies highlight the central role of ROS in physiological endothelial signaling. Recent Advances: New evidence has uncovered that EC ROS are fundamental in determining how ECs interact with their environment and respond to stress. EC ROS levels are mediated by external factors such as diet and pathogens, as well as inherent characteristics, including sex and location. Changes in EC ROS impact EC function, leading to changes in metabolism, cell communication, and potentially disrupted signaling in CVDs. Critical Issues: Current endothelial biology concepts integrate the dual nature of ROS, emphasizing the importance of EC ROS in physiological stress adaptation and their contribution to CVDs. Understanding the discrete, localized signaling of EC ROS will be critical in preventing adverse cardiovascular outcomes. Future Directions: Exploring how the EC ROS environment alters EC function and cross-cellular communication is critical. Considering the inherent heterogeneity among EC populations and understanding how EC ROS contribute to this diversity and the role of sexual dimorphism in the EC ROS environment will be fundamental for developing new effective cardiovascular treatment strategies.

Metal ions overloading and cell death

Cell death maintains cell morphology and homeostasis during development by removing damaged or obsolete cells. The concentration of metal ions whithin cells is regulated by various intracellular transporters and repositories to maintain dynamic balance. External or internal stimuli might increase the concentration of metal ions, which results in ions overloading. Abnormal accumulation of large amounts of metal ions can lead to disruption of various signaling in the cell, which in turn can produce toxic effects and lead to the occurrence of different types of cell deaths. In order to further study the occurrence and development of metal ions overloading induced cell death, this paper reviewed the regulation of Ca2+, Fe3+, Cu2+ and Zn2+ metal ions, and the internal mechanism of cell death induced by overloading. Furthermore, we found that different metal ions possess a synergistic and competitive relationship in the regulation of cell death. And the enhanced level of oxidative stress was present in all the processes of cell death due to metal ions overloading, which possibly due to the combination of factors. Therefore, this review offers a theoretical foundation for the investigation of the toxic effects of metal ions, and presents innovative insights for targeted regulation and therapeutic intervention. HIGHLIGHTS: • Metal ions overloading disrupts homeostasis, which in turn affects the regulation of cell death. • Metal ions overloading can cause cell death via reactive oxygen species (ROS). • Different metal ions have synergistic and competitive relationships for regulating cell death.

Ferroptosis-A Shared Mechanism for Parkinson's Disease and Type 2 Diabetes

Type 2 diabetes (T2D) and Parkinson's disease (PD) are the two most frequent age-related chronic diseases. There are many similarities between the two diseases: both are chronic diseases; both are the result of a decrease in a specific substance-insulin in T2D and dopamine in PD; and both are caused by the destruction of specific cells-beta pancreatic cells in T2D and dopaminergic neurons in PD. Recent epidemiological and experimental studies have found that there are common underlying mechanisms in the pathophysiology of T2D and PD: chronic inflammation, mitochondrial dysfunction, impaired protein handling and ferroptosis. Epidemiological research has indicated that there is a higher risk of PD in individuals with T2D. Moreover, clinical studies have observed that the symptoms of Parkinson's disease worsen significantly after the onset of T2D. This article provides an up-to-date review on the intricate interplay between oxidative stress, reactive oxygen species (ROS) and ferroptosis in PD and T2D. By understanding the shared molecular pathways and how they can be modulated, we can develop more effective therapies, or we can repurpose existing drugs to improve patient outcomes in both disorders.

Targeting amino acid-metabolizing enzymes for cancer immunotherapy

Despite the immune system's role in the detection and eradication of abnormal cells, cancer cells often evade elimination by exploitation of various immune escape mechanisms. Among these mechanisms is the ability of cancer cells to upregulate amino acid-metabolizing enzymes, or to induce these enzymes in tumor-infiltrating immunosuppressive cells. Amino acids are fundamental cellular nutrients required for a variety of physiological processes, and their inadequacy can severely impact immune cell function. Amino acid-derived metabolites can additionally dampen the anti-tumor immune response by means of their immunosuppressive activities, whilst some can also promote tumor growth directly. Based on their evident role in tumor immune escape, the amino acid-metabolizing enzymes glutaminase 1 (GLS1), arginase 1 (ARG1), inducible nitric oxide synthase (iNOS), indoleamine 2,3-dioxygenase 1 (IDO1), tryptophan 2,3-dioxygenase (TDO) and interleukin 4 induced 1 (IL4I1) each serve as a promising target for immunotherapeutic intervention. This review summarizes and discusses the involvement of these enzymes in cancer, their effect on the anti-tumor immune response and the recent progress made in the preclinical and clinical evaluation of inhibitors targeting these enzymes.

Acute Hyperglycemia-Induced Injury in Myocardial Infarction

Acute hyperglycemia is a transient increase in plasma glucose level (PGL) frequently observed in patients with ST-elevation myocardial infarction (STEMI). The aim of this review is to clarify the molecular mechanisms whereby acute hyperglycemia impacts coronary flow and myocardial perfusion in patients with acute myocardial infarction (AMI) and to discuss the consequent clinical and prognostic implications. We conducted a comprehensive literature review on the molecular causes of myocardial damage driven by acute hyperglycemia in the context of AMI. The negative impact of high PGL on admission recognizes a multifactorial etiology involving endothelial function, oxidative stress, production of leukocyte adhesion molecules, platelet aggregation, and activation of the coagulation cascade. The current evidence suggests that all these pathophysiological mechanisms compromise myocardial perfusion as a whole and not only in the culprit coronary artery. Acute hyperglycemia on admission, regardless of whether or not in the context of a diabetes mellitus history, could be, thus, identified as a predictor of worse myocardial reperfusion and poorer prognosis in patients with AMI. In order to reduce hyperglycemia-related complications, it seems rational to pursue in these patients an adequate and quick control of PGL, despite the best pharmacological treatment for acute hyperglycemia still remaining a matter of debate.

Metabolic Responses to Redox Stress in Vascular Cells

Significance: Redox stress underlies numerous vascular disease mechanisms. Metabolic adaptability is essential for vascular cells to preserve energy and redox homeostasis. Recent Advances: Single-cell technologies and multiomic studies demonstrate significant metabolic heterogeneity among vascular cells in health and disease. Increasing evidence shows that reductive or oxidative stress can induce metabolic reprogramming of vascular cells. A recent example is intracellular L-2-hydroxyglutarate accumulation in response to hypoxic reductive stress, which attenuates the glucose flux through glycolysis and mitochondrial respiration in pulmonary vascular cells and provides protection against further reductive stress. Critical Issues: Regulation of cellular redox homeostasis is highly compartmentalized and complex. Vascular cells rely on multiple metabolic pathways, but the precise connectivity among these pathways and their regulatory mechanisms is only partially defined. There is also a critical need to understand better the cross-regulatory mechanisms between the redox system and metabolic pathways as perturbations in either systems or their cross talk can be detrimental. Future Directions: Future studies are needed to define further how multiple metabolic pathways are wired in vascular cells individually and as a network of closely intertwined processes given that a perturbation in one metabolic compartment often affects others. There also needs to be a comprehensive understanding of how different types of redox perturbations are sensed by and regulate different cellular metabolic pathways with specific attention to subcellular compartmentalization. Lastly, integration of dynamic changes occurring in multiple metabolic pathways and their cross talk with the redox system is an important goal in this multiomics era.

Comprehensive bioinformatics analysis of structural and functional consequences of deleterious missense mutations in the human QDPR gene

Quinonoid dihydropteridine reductase (QDPR) is an enzyme that regulates tetrahydrobiopterin (BH4), a cofactor for enzymes involved in neurotransmitter synthesis and blood pressure regulation. Reduced QDPR activity can cause dihydrobiopterin (BH2) accumulation and BH4 depletion, leading to impaired neurotransmitter synthesis, oxidative stress, and increased risk of Parkinson's disease. A total of 10,236 SNPs were identified in the QDPR gene, with 217 being missense SNPs. Over 18 different sequence-based and structure-based tools were employed to assess the protein's biological activity, with several computational tools identifying deleterious SNPs. Additionally, the article provides detailed information about the QDPR gene and protein structure and conservation analysis. The results showed that 10 mutations were harmful and linked to brain and central nervous system disorders, and were predicted to be oncogenic by Dr. Cancer and CScape. Following conservation analysis, the HOPE server was used to analyse the effect of six selected mutations (L14P, V15G, G23S, V54G, M107K, G151S) on the protein structure. Overall, the study provides insights into the biological and functional impact of nsSNPs on QDPR activity and the potential induced pathogenicity and oncogenicity. In the future, research can be conducted to systematically evaluate QDPR gene variation through clinical studies, investigate mutation prevalence across different geographical regions, and validate computational results with conclusive experiments.Communicated by Ramaswamy H. Sarma.

Exploring the therapeutic potential of tetrahydrobiopterin for heart failure with preserved ejection fraction: A path forward

A large number of patients are affected by classical heart failure (HF) symptomatology with preserved ejection fraction (HFpEF) and multiorgan syndrome. Due to high morbidity and mortality rate, hospitalization and mortality remain serious socioeconomic problems, while the lack of effective pharmacological or device treatment means that HFpEF presents a major unmet medical need. Evidence from clinical and basic studies demonstrates that systemic inflammation, increased oxidative stress, and impaired mitochondrial function are the common pathological mechanisms in HFpEF. Tetrahydrobiopterin (BH4), beyond being an endogenous co-factor for catalyzing the conversion of some essential biomolecules, has the capacity to prevent systemic inflammation, enhance antioxidant resistance, and modulate mitochondrial energy production. Therefore, BH4 has emerged in the last decade as a promising agent to prevent or reverse the progression of disorders such as cardiovascular disease. In this review, we cover the clinical progress and limitations of using downstream targets of nitric oxide (NO) through NO donors, soluble guanylate cyclase activators, phosphodiesterase inhibitors, and sodium-glucose co-transporter 2 inhibitors in treating cardiovascular diseases, including HFpEF. We discuss the use of BH4 in association with HFpEF, providing new evidence for its potential use as a pharmacological option for treating HFpEF.

Sterile inflammation induces vasculopathy and chronic lung injury in murine sickle cell disease

Murine sickle cell disease (SCD) results in damage to multiple organs, likely mediated first by vasculopathy. While the mechanisms inducing vascular damage remain to be determined, nitric oxide bioavailability and sterile inflammation are both considered to play major roles in vasculopathy. Here, we investigate the effects of high mobility group box-1 (HMGB1), a pro-inflammatory damage-associated molecular pattern (DAMP) molecule on endothelial-dependent vasodilation and lung morphometrics, a structural index of damage in sickle (SS) mice. SS mice were treated with either phosphate-buffered saline (PBS), hE-HMGB1-BP, an hE dual-domain peptide that binds and removes HMGB1 from the circulation via the liver, 1-[4-(aminocarbonyl)-2-methylphenyl]-5-[4-(1H-imidazol-1-yl)phenyl]-1H-pyrrole-2-propanoic acid (N6022) or N-acetyl-lysyltyrosylcysteine amide (KYC) for three weeks. Human umbilical vein endothelial cells (HUVEC) were treated with recombinant HMGB1 (r-HMGB1), which increases S-nitrosoglutathione reductase (GSNOR) expression by ∼80%, demonstrating a direct effect of HMGB1 to increase GSNOR. Treatment of SS mice with hE-HMGB1-BP reduced plasma HMGB1 in SS mice to control levels and reduced GSNOR expression in facialis arteries isolated from SS mice by ∼20%. These changes were associated with improved endothelial-dependent vasodilation. Treatment of SS mice with N6022 also improved vasodilation in SS mice suggesting that targeting GSNOR also improves vasodilation. SCD decreased protein nitrosothiols (SNOs) and radial alveolar counts (RAC) and increased GSNOR expression and mean linear intercepts (MLI) in lungs from SS mice. The marked changes in pulmonary morphometrics and GSNOR expression throughout the lung parenchyma in SS mice were improved by treating with either hE-HMGB1-BP or KYC. These data demonstrate that murine SCD induces vasculopathy and chronic lung disease by an HMGB1- and GSNOR-dependent mechanism and suggest that HMGB1 and GSNOR might be effective therapeutic targets for reducing vasculopathy and chronic lung disease in humans with SCD.

Effect of reactive oxygen, nitrogen, and sulfur species on signaling pathways in atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which fats, lipids, cholesterol, calcium, proliferating smooth muscle cells, and immune cells accumulate in the intima of the large arteries, forming atherosclerotic plaques. A complex interplay of various vascular and immune cells takes place during the initiation and progression of atherosclerosis. Multiple reports indicate that tight control of reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) production is critical for maintaining vascular health. Unrestricted ROS and RNS generation may lead to activation of various inflammatory signaling pathways, facilitating atherosclerosis. Given these deleterious consequences, it is important to understand how ROS and RNS affect the signaling processes involved in atherogenesis. Conversely, RSS appears to exhibit an atheroprotective potential and can alleviate the deleterious effects of ROS and RNS. Herein, we review the literature describing the effects of ROS, RNS, and RSS on vascular smooth muscle cells, endothelial cells, and macrophages and focus on how changes in their production affect the initiation and progression of atherosclerosis. This review also discusses the contribution of ROS, RNS, and RSS in mediating various post-translational modifications, such as oxidation, nitrosylation, and sulfation, of the molecules involved in inflammatory signaling.

Biopterin metabolism and nitric oxide recoupling in cancer

Tetrahydrobiopterin is a cofactor necessary for the activity of several enzymes, the most studied of which is nitric oxide synthase. The role of this cofactor-enzyme relationship in vascular biology is well established. Recently, tetrahydrobiopterin metabolism has received increasing attention in the field of cancer immunology and immunotherapy due to its involvement in the cytotoxic T cell response. Past research has demonstrated that when the availability of BH4 is low, as it is in chronic inflammatory conditions and tumors, electron transfer in the active site of nitric oxide synthase becomes uncoupled from the oxidation of arginine. This results in the production of radical species that are capable of a direct attack on tetrahydrobiopterin, further depleting its local availability. This feedforward loop may act like a molecular switch, reinforcing low tetrahydrobiopterin levels leading to altered NO signaling, restrained immune effector activity, and perpetual vascular inflammation within the tumor microenvironment. In this review, we discuss the evidence for this underappreciated mechanism in different aspects of tumor progression and therapeutic responses. Furthermore, we discuss the preclinical evidence supporting a clinical role for tetrahydrobiopterin supplementation to enhance immunotherapy and radiotherapy for solid tumors and the potential safety concerns.

Differential superoxide production in phosphorylated neuronal nitric oxide synthase mu and alpha variants

Neuronal nitric oxide synthase (nNOS) is regulated by phosphorylation in vivo, yet the underlying biochemical mechanisms remain unclear, primarily due to difficulty in obtaining milligram quantities of phosphorylated nNOS protein; detailed spectroscopic and rapid kinetics investigations require purified protein samples at a concentration in the range of hundreds microM. Moreover, the functional diversity of the nNOS isoform is linked to its splice variants. Also of note is that determination of protein phosphorylation stoichiometry remains as a challenge. To address these issues, this study first expanded a recent genetic code expansion approach to produce phosphorylated rat nNOSμ and nNOSα holoproteins through site-specific incorporation of phosphoserine (pSer) at residues 1446 and 1412, respectively; this site is at the C-terminal tail region, a NOS-unique regulatory element. A quantitative mass spectrometric approach was then developed in-house to analyze unphosphorylated peptides in phosphatase-treated and -untreated phospho-nNOS proteins. The observed pSer-incorporation efficiency consistently exceeded 80%, showing high pSer-incorporation efficiency. Notably, EPR spin trapping results demonstrate that under l-arginine-depleted conditions, pSer1412 nNOSα presented a significant reduction in superoxide generation, whereas pSer1446 nNOSμ exhibited the opposite effect, compared to their unphosphorylated counterparts. This suggests that phosphorylation at the C-terminal tail has a regulatory effect on nNOS uncoupling that may differ between variant forms. Furthermore, the methodologies for incorporating pSer into large, complex protein and quantifying the percentage of phosphorylation in recombinant purified protein should be applicable to other protein systems.

The Alzheimer's Disease Brain, Its Microvasculature, and NADPH Oxidase

The deterioration of the brain's microvasculature, particularly in the hippocampus, appears to be a very early event in the development of Alzheimer's disease (AD), preceding even the deposition of amyloid-β. A damaged microvasculature reduces the supply of oxygen and glucose to this region and limits the production of energy, ATP. The damage may be a function of the rise with age in the expression and activity of NADPH oxidase (NOX) in these microvessels. This rise renders these vessels vulnerable to the effects of oxidative stress and inflammation. The rise in NOX activity with age is even more marked in the AD brain where an inverse correlation has been demonstrated between NOX activity and cognitive ability. Apocynin, a putative NOX inhibitor, has been shown to block the damaging effects of NOX activation. Apocynin acts as a strong scavenger of H2O2, and as a weak scavenger of superoxide. Like apocynin, sodium oxybate (SO) has also been shown to block the toxic effects of NOX activation. The application of SO generates NADPH and ATP. SO inhibits oxidative stress and maintains normal cerebral ATP levels under hypoxic conditions. Moreover, it acts epigenetically to attenuate the expression of NOX. SO may delay the onset and slow the progress of AD by suppling energy and maintaining an antioxidative environment in the brain throughout the night. The slow wave activity produced by SO may also activate the glymphatic system and promote the clearance of amyloid-β from the brain.

From Stress to Sick(le) and Back Again-Oxidative/Antioxidant Mechanisms, Genetic Modulation, and Cerebrovascular Disease in Children with Sickle Cell Anemia

Sickle cell anemia (SCA) is a genetic disease caused by the homozygosity of the HBB:c.20A>T mutation, which results in the production of hemoglobin S (HbS). In hypoxic conditions, HbS suffers autoxidation and polymerizes inside red blood cells, altering their morphology into a sickle shape, with increased rigidity and fragility. This triggers complex pathophysiological mechanisms, including inflammation, cell adhesion, oxidative stress, and vaso-occlusion, along with metabolic alterations and endocrine complications. SCA is phenotypically heterogeneous due to the modulation of both environmental and genetic factors. Pediatric cerebrovascular disease (CVD), namely ischemic stroke and silent cerebral infarctions, is one of the most impactful manifestations. In this review, we highlight the role of oxidative stress in the pathophysiology of pediatric CVD. Since oxidative stress is an interdependent mechanism in vasculopathy, occurring alongside (or as result of) endothelial dysfunction, cell adhesion, inflammation, chronic hemolysis, ischemia-reperfusion injury, and vaso-occlusion, a brief overview of the main mechanisms involved is included. Moreover, the genetic modulation of CVD in SCA is discussed. The knowledge of the intricate network of altered mechanisms in SCA, and how it is affected by different genetic factors, is fundamental for the identification of potential therapeutic targets, drug development, and patient-specific treatment alternatives.

Arginase-1 promotes lens epithelial-to-mesenchymal transition in different models of anterior subcapsular cataract

BACKGROUND

Arginase-1 (ARG1) promotes collagen synthesis and cell proliferation. ARG1 is highly expressed in various tumour cells. The mechanisms of ARG1 in epithelial-to-mesenchymal transition (EMT)-associated cataracts were studied herein.

METHODS

C57BL/6 mice, a human lens epithelial cell line (HLEC-SRA01/04), and human lens capsule samples were used in this study. The right lens anterior capsule of the mouse eye was punctured through the central cornea with a 26-gauge hypodermic needle. Human lens epithelial cells (HLECs) were transfected with ARG1-targeted (siARG1) or negative control siRNA (siNC). For gene overexpression, HLECs were transfected with a plasmid bearing the ARG1 coding sequence or an empty vector. Medium containing 0.2% serum with or without transforming growth factor beta-2 (TGF-β2) was added for 6 or 24 h to detect mRNA or protein, respectively. The expression of related genes was measured by quantitative real-time polymerase chain reaction (RT-qPCR), western blotting, and immunohistochemical staining. Transwell assays and wound healing assays were used to determine cell migration. Cell proliferation, superoxide levels, nitric oxide (NO) levels, and arginase activity were estimated using Cell Counting Kit-8 assays, a superoxide assay kit, an NO assay kit, and an arginase activity kit.

RESULTS

ARG1, alpha-smooth muscle actin (α-SMA), fibronectin, and Ki67 expression increased after lens capsular injury, while zonula occludens-1 (ZO-1) expression decreased. Fibronectin and collagen type I alpha1 chain (collagen 1A1) expression increased, and cell migration increased significantly in ARG1-overexpressing HLECs compared with those transfected with an empty vector after TGF-β2 treatment. These effects were reversed by ARG1 knockdown. The arginase-related pathway plays an important role in EMT. mRNAs of enzymes of the arginase-related pathway were highly expressed after ARG1 overexpression. ARG1 knockdown suppressed these expression changes. Numidargistat (CB-1158) dihydrochloride (CB-1158), an ARG1 inhibitor, suppressed TGF-β2-induced anterior subcapsular cataract (ASC) by reducing the proliferation of lens epithelial cells (LECs) and decreasing fibronectin, α-SMA, collagen 1A1, and vimentin expression. Compared with that in nonanterior subcapsular cataract (non-ASC) patients, the expression of ARG1, collagen 1A1, vimentin, fibronectin, and Ki67 was markedly increased in ASC patients.

CONCLUSIONS

ARG1 can regulate EMT in EMT-associated cataracts. Based on the pathogenesis of ASC, these findings are expected to provide new therapeutic strategies for patients.

Niclosamide Inhibits Aortic Valve Interstitial Cell Calcification by Interfering with the GSK-3β/β-Catenin Signaling Pathway

The most common heart valve disorder is calcific aortic valve stenosis (CAVS), which is characterized by a narrowing of the aortic valve. Treatment with the drug molecule, in addition to surgical and transcatheter valve replacement, is the primary focus of researchers in this field. The purpose of this study is to determine whether niclosamide can reduce calcification in aortic valve interstitial cells (VICs). To induce calcification, cells were treated with a pro-calcifying medium (PCM). Different concentrations of niclosamide were added to the PCM-treated cells, and the level of calcification, mRNA, and protein expression of calcification markers was measured. Niclosamide inhibited aortic valve calcification as observed from reduced alizarin red s staining in niclosamide treated VICs and also decreased the mRNA and protein expressions of calcification-specific markers: runt-related transcription factor 2 and osteopontin. Niclosamide also reduced the formation of reactive oxygen species, NADPH oxidase activity and the expression of Nox2 and p22phox. Furthermore, in calcified VICs, niclosamide inhibited the expression of β-catenin and phosphorylated glycogen synthase kinase (GSK-3β), as well as the phosphorylation of AKT and ERK. Taken together, our findings suggest that niclosamide may alleviate PCM-induced calcification, at least in part, by targeting oxidative stress mediated GSK-3β/β-catenin signaling pathway via inhibiting activation of AKT and ERK, and may be a potential treatment for CAVS.

Redox Biology in Adipose Tissue Physiology and Obesity

Reactive oxygen species (ROS), a by-product of mitochondrial oxidative phosphorylation and cellular metabolism, is vital for cellular survival, proliferation, damage, and senescence. In recent years, studies have shown that ROS levels and redox status in adipose tissue are strongly associated with obesity and metabolic diseases. Although it was previously considered that excessive production of ROS and impairment of antioxidant capability leads to oxidative stress and potentially contributes to increased adiposity, it has become increasingly evident that an adequate amount of ROS is vital for adipocyte differentiation and thermogenesis. In this review, by providing a systematic overview of the recent understanding of the key factors of redox systems, endogenous mechanisms for redox homeostasis, advanced techniques for dynamic redox monitoring, as well as exogenous stimuli for redox production in adipose tissues and obesity, the importance of redox biology in metabolic health is emphasized.

A Reappraisal of the Utility of L-012 to Measure Superoxide from Biologically Relevant Sources

The detection of superoxide anion (O2●-) in biological tissues remains challenging. Barriers to convenient and reproducible measurements include expensive equipment, custom probes, and the need for high sensitivity and specificity. The luminol derivative, L-012, has been used to measure O2●- since 1993 with mixed results and concerns over specificity. The goal of this study was to better define the conditions for use and their specificity. We found that L-012 coupled with depolymerized orthovanadate, a relatively impermeable tyrosine phosphatase inhibitor, yielded a highly sensitive approach to detect extracellular O2●-. In O2●- producing HEK-NOX5 cells, orthovanadate increased L-012 luminescence 100-fold. The combination of L-012 and orthovanadate was highly sensitive, stable, scalable, completely reversed by superoxide dismutase, and selective for O2●- generating NOXes versus NOX4, which produces H2O2. Moreover, there was no signal from cells transfected with NOS3 (NO●) and NOS2(ONOO-). To exclude the effects of altered tyrosine phosphorylation, O2●- was detected using non-enzymatic synthesis with phenazine methosulfate and via novel coupling of L-012 with niobium oxalate, which was less active in inducing tyrosine phosphorylation. Overall, our data shows that L-012 coupled with orthovanadate or other periodic group 5 salts yields a reliable, sensitive, and specific approach to measuring extracellular O2●- in biological systems.

Therapeutic potential of nitric oxide in vascular aging due to the promotion of angiogenesis

The decrease in angiogenesis that occurs with aging significantly contributes to the higher incidence and mortality of cardiovascular diseases among the elderly. This decline in angiogenesis becomes more pronounced with increasing age and is closely linked to abnormal function and senescence of endothelial cells. Enhancing angiogenesis in aging and targeting senescent endothelial cells have gained considerable attention. Nitric oxide (NO) has been thoroughly investigated for its function in regulating angiogenesis and is an important factor that can counteract endothelial cell senescence. This review summarizes the mechanisms of reduced angiogenesis during aging and therapeutic strategies targeting senescent cells. We also discuss the potential of combining the current approaches with NO in promoting angiogenesis in aging vessels.

Metabolic reprogramming, oxidative stress, and pulmonary hypertension

Mitochondria are highly dynamic organelles essential for cell metabolism, growth, and function. It is becoming increasingly clear that endothelial cell dysfunction significantly contributes to the pathogenesis and vascular remodeling of various lung diseases, including pulmonary arterial hypertension (PAH), and that mitochondria are at the center of this dysfunction. The more we uncover the role mitochondria play in pulmonary vascular disease, the more apparent it becomes that multiple pathways are involved. To achieve effective treatments, we must understand how these pathways are dysregulated to be able to intervene therapeutically. We know that nitric oxide signaling, glucose metabolism, fatty acid oxidation, and the TCA cycle are abnormal in PAH, along with alterations in the mitochondrial membrane potential, proliferation, and apoptosis. However, these pathways are incompletely characterized in PAH, especially in endothelial cells, highlighting the urgent need for further research. This review summarizes what is currently known about how mitochondrial metabolism facilitates a metabolic shift in endothelial cells that induces vascular remodeling during PAH.

Why Are Perivascular Spaces Important?

Perivascular spaces (PVS) and their enlargement (EPVS) have been gaining interest as EPVS can be visualized non-invasively by magnetic resonance imaging (MRI) when viewing T-2-weighted images. EPVS are most commonly observed in the regions of the basal ganglia and the centrum semiovale; however, they have also been identified in the frontal cortex and hippocampal regions. EPVS are known to be increased in aging and hypertension, and are considered to be a biomarker of cerebral small vessel disease (SVD). Interest in EPVS has been significantly increased because these PVS are now considered to be an essential conduit necessary for the glymphatic pathway to provide the necessary efflux of metabolic waste. Metabolic waste includes misfolded proteins of amyloid beta and tau that are known to accumulate in late-onset Alzheimer's disease (LOAD) within the interstitial fluid that is delivered to the subarachnoid space and eventually the cerebral spinal fluid (CSF). The CSF acts as a sink for accumulating neurotoxicities and allows clinical screening to potentially detect if LOAD may be developing early on in its clinical progression via spinal fluid examination. EPVS are thought to occur by obstruction of the PVS that associates with excessive neuroinflammation, oxidative stress, and vascular stiffening that impairs flow due to a dampening of the arterial and arteriolar pulsatility that aids in the convective flow of the metabolic debris within the glymphatic effluxing system. Additionally, increased EPVS has also been associated with Parkinson's disease and non-age-related multiple sclerosis (MS).

Oxidative stress and valvular endothelial cells in aortic valve calcification

Calcified aortic valve disease (CAVD) is a common cardiovascular disease in elderly individuals. Although it was previously considered a degenerative disease, it is, in fact, a progressive disease involving multiple mechanisms. Aortic valve endothelial cells, which cover the outermost layer of the aortic valve and are directly exposed to various pathogenic factors, play a significant role in the onset and progression of CAVD. Hemodynamic changes can directly damage the structure and function of valvular endothelial cells (VECs). This leads to inflammatory infiltration and oxidative stress, which promote the progression of CAVD. VECs can regulate the pathological differentiation of valvular interstitial cells (VICs) through NO and thus affect the process of CAVD. Under the influence of pathological factors, VECs can also be transformed into VICs through EndMT, and then the pathological differentiation of VICs eventually leads to the formation of calcification. This review discusses the role of VECs, especially the role of oxidative stress in VECs, in the process of aortic valve calcification.

Low Grade Endotoxemia and Oxidative Stress in Offspring of Patients with Early Myocardial Infarction

Background and aims: Offspring of patients with early myocardial infarction are at higher cardiovascular risk, but the underlying physio-pathological mechanism is unclear. NADPH oxidase-type 2 (NOX-2) plays a pivotal role as mediator of oxidative stress and could be involved in activating platelets in these patients. Furthermore, altered intestinal permeability and serum lipopolysaccharide (LPS) could be a trigger to promote NOX-2 activation and platelet aggregation. This study aims to evaluate the behavior of low grade endotoxemia, oxidative stress and platelet activation in offspring of patients with early myocardial infarction. Methods: We enrolled, in a cross-sectional study, 46 offspring of patients with early myocardial infarction and 86 healthy subjects (HS). LPS levels and gut permeability (assessed by zonulin), oxidative stress (assessed by serum NOX-2-derived peptide (sNOX2-dp) release, hydrogen peroxide (H₂O₂) production and isoprostanes), serum nitric oxide (NO) bioavailability and platelet activation (by serum thromboxane B2 (TXB2) and soluble P-Selectin (sP-Selectin)) were analyzed. Results: Compared to HS, offspring of patients with early myocardial infarction had higher values of LPS, zonulin, serum isoprostanes, sNOX2-dp H₂O₂, TXB2, p-selectin and lower NO bioavailability. Logistic regression analysis showed that the variables associated with offspring of patients with early myocardial infarction were LPS, TXB2 and isoprostanes. The multiple linear regression analysis confirmed that serum NOX-2, isoprostanes, p-selectin and H₂O₂ levels were significantly associated to LPS. Furthermore, serum LPS, isoprostanes and TXB2 levels were significantly associated with sNOX-2-dp. Conclusions: Offspring of patients with early myocardial infarction have a low grade endotoxemia that could generate oxidative stress and platelet activation increasing their cardiovascular risk. Future studies are needed to understand the role of dysbiosis in this population.

Maternal nutrition and effects on offspring vascular function

Maternal nutrition during pregnancy may have profound effects on the developing fetus and impact risk for cardiovascular disease later in life. Here, we provide a narrative review on the impact of maternal diet during pregnancy on offspring vascular function. We review studies reporting effects of maternal micronutrient (folic acid, iron) intakes, high-fat diets, dietary energy restriction, and low protein intake on offspring endothelial function. We discuss the differences in study design and outcomes and potential underlying mechanisms contributing to the vascular phenotypes observed in the offspring. We further highlight key gaps in the literature and identify targets for future investigations.

Endothelial cell-specific roles for tetrahydrobiopterin in myocardial function, cardiac hypertrophy, and response to myocardial ischemia-reperfusion injury

The cofactor tetrahydrobiopterin (BH4) is a critical regulator of nitric oxide synthase (NOS) function and redox signaling, with reduced BH4 implicated in multiple cardiovascular disease states. In the myocardium, augmentation of BH4 levels can impact on cardiomyocyte function, preventing hypertrophy and heart failure. However, the specific role of endothelial cell BH4 biosynthesis in the coronary circulation and its role in cardiac function and the response to ischemia has yet to be elucidated. Endothelial cell-specific Gch1 knockout mice were generated by crossing Gch1fl/fl with Tie2cre mice, generating Gch1fl/flTie2cre mice and littermate controls. GTP cyclohydrolase protein and BH4 levels were reduced in heart tissues from Gch1fl/flTie2cre mice, localized to endothelial cells, with normal cardiomyocyte BH4. Deficiency in coronary endothelial cell BH4 led to NOS uncoupling, decreased NO bioactivity, and increased superoxide and hydrogen peroxide productions in the hearts of Gch1fl/flTie2cre mice. Under physiological conditions, loss of endothelial cell-specific BH4 led to mild cardiac hypertrophy in Gch1fl/flTie2cre hearts. Endothelial cell BH4 loss was also associated with increased neuronal NOS protein, loss of endothelial NOS protein, and increased phospholamban phosphorylation at serine-17 in cardiomyocytes. Loss of cardiac endothelial cell BH4 led to coronary vascular dysfunction, reduced functional recovery, and increased myocardial infarct size following ischemia-reperfusion injury. Taken together, these studies reveal a specific role for endothelial cell Gch1/BH4 biosynthesis in cardiac function and the response to cardiac ischemia-reperfusion injury. Targeting endothelial cell Gch1 and BH4 biosynthesis may provide a novel therapeutic target for the prevention and treatment of cardiac dysfunction and ischemia-reperfusion injury.NEW & NOTEWORTHY We demonstrate a critical role for endothelial cell Gch1/BH4 biosynthesis in coronary vascular function and cardiac function. Loss of cardiac endothelial cell BH4 leads to coronary vascular dysfunction, reduced functional recovery, and increased myocardial infarct size following ischemia/reperfusion injury. Targeting endothelial cell Gch1 and BH4 biosynthesis may provide a novel therapeutic target for the prevention and treatment of cardiac dysfunction, ischemia injury, and heart failure.

Overview and New Insights into the Metabolic Syndrome: Risk Factors and Emerging Variables in the Development of Type 2 Diabetes and Cerebrocardiovascular Disease

Metabolic syndrome (MetS) is considered a metabolic disorder that has been steadily increasing globally and seems to parallel the increasing prevalence of obesity. It consists of a cluster of risk factors which traditionally includes obesity and hyperlipidemia, hyperinsulinemia, hypertension, and hyperglycemia. These four core risk factors are associated with insulin resistance (IR) and, importantly, the MetS is known to increase the risk for developing cerebrocardiovascular disease and type 2 diabetes mellitus. The MetS had its early origins in IR and syndrome X. It has undergone numerous name changes, with additional risk factors and variables being added over the years; however, it has remained as the MetS worldwide for the past three decades. This overview continues to add novel insights to the MetS and suggests that leptin resistance with hyperleptinemia, aberrant mitochondrial stress and reactive oxygen species (ROS), impaired folate-mediated one-carbon metabolism with hyperhomocysteinemia, vascular stiffening, microalbuminuria, and visceral adipose tissues extracellular vesicle exosomes be added to the list of associated variables. Notably, the role of a dysfunctional and activated endothelium and deficient nitric oxide bioavailability along with a dysfunctional and attenuated endothelial glycocalyx, vascular inflammation, systemic metainflammation, and the important role of ROS and reactive species interactome are discussed. With new insights and knowledge regarding the MetS comes the possibility of new findings through further research.

Early Detection Is the Best Prevention-Characterization of Oxidative Stress in Diabetes Mellitus and Its Consequences on the Cardiovascular System

Previous studies demonstrated an important role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) in diabetic patients due to hyperglycemia. CVD remains the leading cause of premature death in the western world. Therefore, diabetes mellitus-associated oxidative stress and subsequent inflammation should be recognized at the earliest possible stage to start with the appropriate treatment before the onset of the cardiovascular sequelae such as arterial hypertension or coronary artery disease (CAD). The pathophysiology comprises increased reactive oxygen and nitrogen species (RONS) production by enzymatic and non-enzymatic sources, e.g., mitochondria, an uncoupled nitric oxide synthase, xanthine oxidase, and the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). Considering that RONS originate from different cellular mechanisms in separate cellular compartments, adequate, sensitive, and compartment-specific methods for their quantification are crucial for early detection. In this review, we provide an overview of these methods with important information for early, appropriate, and effective treatment of these patients and their cardiovascular sequelae.

Possible role of the NLRP3 inflammasome and the gut-brain axis in multiple sclerosis-related depression

Multiple sclerosis (MS) is an autoimmune and demyelinating disease of the central nervous system that results from complex interactions between genetic and environmental determinants. Patients with MS exhibit a high risk of depression, however, the exact pathomechanisms remain largely unknown. It is becoming widely accepted that the gut-brain axis (GBA) disorders may exert an influence on neuroinflammation and psychiatric symptoms, including so-called MS-related depression. The element suggested as a bridge between intestinal disorders, depression, and MS is an inflammatory response with the central role of the NLR family pyrin domain containing 3 (NLRP3) inflammasome. The pro-inflammatory activity of effector cytokines of the NLRP3 inflammasome forms the hypothesis that it is actively involved in the development of inflammatory and autoimmune diseases. Despite extensive reviews considering the possible origins of MS-related depression, its complex pathophysiology prevents any easy determination of its underlying mechanisms. This paper aims to discuss molecular mechanisms related to the GBA axis that can mediate dysbiosis, intestinal barrier dysfunction, disruption of blood-brain barrier integrity, neuroinflammation, and subsequent manifestation of MS-related major depressive disorder.

A critical review on anti-fibrotic phytochemicals targeting activated hepatic stellate cells

Liver fibrosis is a major health concern occurring worldwide. It arises due to prolonged wound healing response of various insults like viral, autoimmune, cholestatic, drug-induced, and metabolic diseases. Currently, there is no clinically approved drug for liver fibrosis treatment. Hepatic stellate cells are the principal liver cells that are activated during liver fibrosis, and targeting these activated cells is an ideal therapeutic strategy. Numerous phytochemicals have been demonstrated in vitro and in vivo treating experimental liver fibrosis; however, none of them have been clinically approved for therapeutic use. This review mainly focuses on such hepatoprotective phytochemicals reported inhibiting major signaling pathways that are dysregulated in activated hepatic stellate cells. PRACTICAL APPLICATIONS: Liver fibrosis is a global health concern and there is no FDA approved drug to treat liver fibrosis. Although notable pharmacological agents like pentoxifylline, gliotoxin, imatinibmesylate, Gleevec, and so on are reported to exhibit anti-fibrotic effect, the major concern is their side effect. Hence, phytochemicals are promising candidates that could be employed against liver fibrosis. In this review, the anti-fibrotic potential of phytochemicals targeting activated HSCs are summarized. Understanding these phytochemicals will further help in the development of agents that are more effective against liver fibrosis.

The Role of L-Arginine-NO System in Female Reproduction: A Narrative Review

Accumulating evidence are available on the involvement of l-arginine-nitric oxide (NO) system in complex biological processes and numerous clinical conditions. Particular attention was made to reveal the association of l-arginine and methylarginines to outcome measures of women undergoing in vitro fertilization (IVF). This review attempts to summarize the expression and function of the essential elements of this system with particular reference to the different stages of female reproduction. A literature search was performed on the PubMed and Google Scholar systems. Publications were selected for evaluation according to the results presented in the Abstract. The regulatory role of NO during the period of folliculogenesis, oocyte maturation, fertilization, embryogenesis, implantation, placentation, pregnancy, and delivery was surveyed. The major aspects of cellular l-arginine uptake via cationic amino acid transporters (CATs), arginine catabolism by nitric oxide synthases (NOSs) to NO and l-citrulline and by arginase to ornithine, and polyamines are presented. The importance of NOS inhibition by methylated arginines and the redox-sensitive elements of the process of NO generation are also shown. The l-arginine-NO system plays a crucial role in all stages of female reproduction. Insufficiently low or excessively high rates of NO generation may have adverse influences on IVF outcome.

Thermoneutrality induces vascular dysfunction and impaired metabolic function in male Wistar rats: a new model of vascular disease

OBJECTIVE

Cardiovascular disease is of paramount importance, yet there are few relevant rat models to investigate its pathology and explore potential therapeutics. Housing at thermoneutral temperature (30 °C) is being employed to humanize metabolic derangements in rodents. We hypothesized that housing rats in thermoneutral conditions would potentiate a high-fat diet, resulting in diabetes and dysmetabolism, and deleteriously impact vascular function, in comparison to traditional room temperature housing (22 °C).

METHODS

Male Wistar rats were housed at either room temperature or thermoneutral temperatures for 16 weeks on either a low or high-fat diet. Glucose and insulin tolerance tests were conducted at the beginning and end of the study. At the study's conclusion, vasoreactivity and mitochondrial respiration of aorta and carotid were conducted.

RESULTS

We observed diminished vasodilation in vessels from thermoneutral rats ( P  < 0.05), whereas high-fat diet had no effect. This effect was also observed in endothelium-denuded aorta in thermoneutral rats ( P  < 0.05). Vasoconstriction was significantly elevated in aorta of thermoneutral rats ( P  < 0.05). Diminished nitric oxide synthase activity and nitrotyrosine, and elevated glutathione activity were observed in aorta from rats housed under thermoneutral conditions, indicating a climate of lower nitric oxide and excess reactive oxygen species in aorta. Thermoneutral rat aorta also demonstrated less mitochondrial respiration with lipid substrates compared with the controls ( P  < 0.05).

CONCLUSION

Our data support that thermoneutrality causes dysfunctional vasoreactivity, decreased lipid mitochondrial metabolism, and modified cellular signaling. These are critical observations as thermoneutrality is becoming prevalent for translational research models. This new model of vascular dysfunction may be useful for dissection of targetable aspects of cardiovascular disease and is a novel and necessary model of disease.

ROS-triggered endothelial cell death mechanisms: Focus on pyroptosis, parthanatos, and ferroptosis

The endothelium is a single layer of epithelium covering the surface of the vascular system, and it represents a physical barrier between the blood and vessel wall that plays an important role in maintaining intravascular homeostasis. However, endothelial dysfunction or endothelial cell death can cause vascular barrier disruption, vasoconstriction and diastolic dysfunction, vascular smooth muscle cell proliferation and migration, inflammatory responses, and thrombosis, which are closely associated with the progression of several diseases, such as atherosclerosis, hypertension, coronary atherosclerotic heart disease, ischemic stroke, acute lung injury, acute kidney injury, diabetic retinopathy, and Alzheimer's disease. Oxidative stress caused by the overproduction of reactive oxygen species (ROS) is an important mechanism underlying endothelial cell death. Growing evidence suggests that ROS can trigger endothelial cell death in various ways, including pyroptosis, parthanatos, and ferroptosis. Therefore, this review will systematically illustrate the source of ROS in endothelial cells (ECs); reveal the molecular mechanism by which ROS trigger pyroptosis, parthanatos, and ferroptosis in ECs; and provide new ideas for the research and treatment of endothelial dysfunction-related diseases.

Obstructive Sleep Apnoea and Lipid Metabolism: The Summary of Evidence and Future Perspectives in the Pathophysiology of OSA-Associated Dyslipidaemia

Obstructive sleep apnoea (OSA) is associated with cardiovascular and metabolic comorbidities, including hypertension, dyslipidaemia, insulin resistance and atherosclerosis. Strong evidence suggests that OSA is associated with an altered lipid profile including elevated levels of triglyceride-rich lipoproteins and decreased levels of high-density lipoprotein (HDL). Intermittent hypoxia; sleep fragmentation; and consequential surges in the sympathetic activity, enhanced oxidative stress and systemic inflammation are the postulated mechanisms leading to metabolic alterations in OSA. Although the exact mechanisms of OSA-associated dyslipidaemia have not been fully elucidated, three main points have been found to be impaired: activated lipolysis in the adipose tissue, decreased lipid clearance from the circulation and accelerated de novo lipid synthesis. This is further complicated by the oxidisation of atherogenic lipoproteins, adipose tissue dysfunction, hormonal changes, and the reduced function of HDL particles in OSA. In this comprehensive review, we summarise and critically evaluate the current evidence about the possible mechanisms involved in OSA-associated dyslipidaemia.

Markers of Endothelial Dysfunction Are Attenuated by Resveratrol in Preeclampsia

Preeclampsia (PE) is characterized by great endothelial dysfunction, decreased nitric oxide (NO) bioavailability, and higher levels of arginase activity. In the present study, we investigated the potential modulatory effects of trans-resveratrol (RSV) on arginase and endothelial dysfunction biomarkers in endothelial cells exposed to plasma from patients with PE and healthy pregnant (HP) women, and umbilical arteries from patients with PE. Human umbilical vein endothelial cells (HUVECs) were incubated with pooled plasma from 10 HP or 10 PE pregnant women and RSV; umbilical arteries from patients with PE were incubated with RSV; intracellular NO and total reactive oxygen species (ROS) levels were assessed using a probe that interacted with these radicals; total arginase activity was evaluated measuring the urea produced; total antioxidant capacity was measured using the ferric reduction ability power (FRAP) assay; and endothelial dysfunction biomarkers were assessed using qPCR in endothelial cells and umbilical arteries. RSV increased NO levels and decreased total arginase activity in endothelial cells incubated with plasma from patients with PE. In addition, RSV increased total antioxidant capacity and downregulated endothelial dysfunction biomarkers, such as intercellular adhesion molecule-1 (ICAM-1), von Willebrand factor (vWF), and Caspase-3, (CASP-3), in endothelial cells and umbilical arteries from PE patients. RSV treatment positively modulated the L-arginine-NO pathway, decreased arginase activity, and increased antioxidant capacity, in addition to downregulating endothelial dysfunction biomarkers.

Exploring the Mystery of the Tetrahydrobiopterin Synthetic Defect Lethal Mutant leml from Birth to Death in the Silkworm Bombyx mori

Tetrahydrobiopterin (BH4) is a vital coenzyme for several enzymes involved in diverse enzymatic reactions in animals, and BH4 deficiency can lead to metabolic and neurological disorders due to dysfunction in its metabolism. In the silkworm natural homozygous mutant lem^l, the key enzyme sepiapterin reductase (BmSPR) in the de novo synthesis pathway of BH4 is inactivated, resulting in severe deficiency of BH4 synthesis. However, it is not known why the lem^l larvae can survive to the second-instar stage and which pathways lead to their death when BH4 is deficient. Here, we quantified BH4 and found that the fertilized eggs contained large amounts of BH4 transferred from the mother to the offspring, maintaining its normal development in the embryo and the first instar. Subsequently, we investigated the multiple pathways in which BH4 is involved as a cofactor. The results showed that BH4 deficiency in silkworms blocked the melanin synthesis pathway, caused an insufficient degree of epidermal sclerosis, disordered tyrosine metabolism, and damaged mitochondria. On the other hand, BH4 deficiency led to the uncoupling of nitric oxide synthase (BmNOS), a reduced NO production, and a significantly reduced fat in fat body catalyzation by phospholipase A2, resulting in an impaired immune system. Meanwhile, the uncoupling of BmNOS increased the O₂⁻ content, damaged the DNA, and caused the apoptosis of the body cells. Taken together, BH4 is critical for the life and death of lem^l mutants. This study lays a foundation for the further exploration of lepidopteran insects and provides an important basis for the treatment of human BH4 deficiency-related diseases.

Measurement of Tetrahydrobiopterin in Animal Tissue Samples by HPLC with Electrochemical Detection-Protocol Optimization and Pitfalls

Tetrahydrobiopterin (BH4) is an essential cofactor of all nitric oxide synthase isoforms, thus determination of BH4 levels can provide important mechanistic insight into diseases. We established a protocol for high-performance liquid chromatography/electrochemical detection (HPLC/ECD)-based determination of BH4 in tissue samples. We first determined the optimal storage and work-up conditions for authentic BH4 and its oxidation product dihydrobiopterin (BH2) under various conditions (pH, temperature, presence of antioxidants, metal chelators, and storage time). We then applied optimized protocols for detection of BH4 in tissues of septic (induced by lipopolysaccharide [LPS]) rats. BH4 standards in HCl are stabilized by addition of 1,4-dithioerythritol (DTE) and diethylenetriaminepentaacetic acid (DTPA), while HCl was sufficient for BH2 standard stabilization. Overnight storage of BH4 standard solutions at room temperature in HCl without antioxidants caused complete loss of BH4 and the formation of BH2. We further optimized the protocol to separate ascorbate and the BH4 tissue sample and found a significant increase in BH4 in the heart and kidney as well as higher BH4 levels by trend in the brain of septic rats compared to control rats. These findings correspond to reports on augmented nitric oxide and BH4 levels in both animals and patients with septic shock.

Recent advances in the development of active hybrid molecules in the treatment of cardiovascular diseases

Multifactorial nature of the underlying pathophysiology of chronic disorders hinders in the effective treatment and management of many complex diseases. The conventional targeted therapies have limited applications due to highly complicated disease etiology. Cardiovascular diseases (CVDs) are the group of disorders of the heart and blood vessels. Currently, there is limited knowledge on the underlying cellular and molecular mechanisms of many of the CVDs due to their complex pathophysiology and co-morbidities. Their management with conventional medications results in failure due to adverse drug reactions and clinical specificity of solo-targeting drug therapy. Therefore, it is critical to introduce an alternative strategy to treat multi-factorial diseases. In the past few years, discovery and use of multi-targeted drug therapy with hybrid molecules have shown promising results with minimal side effects, and thus considered a most effective approach. In this review article, prominent hybrid molecules combining with different active moieties are reported to synergistically and simultaneously block different pathways involved in CVDs. Here, we provide a critical evaluation and discussion on their pharmacology with mechanistic insights and the structure activity relationship. The timely information provided in this article reveals the recent trends of molecular hybridization to the scientific community interested in CVDs and help them in designing the next generation of multi-targeting drug therapeutics.

Role of oxidative stress in calcific aortic valve disease and its therapeutic implications

Calcific aortic valve disease (CAVD) is the end result of active cellular processes that lead to the progressive fibrosis and calcification of aortic valve leaflets. In western populations, CAVD is a significant cause of cardiovascular morbidity and mortality, and in the absence of effective drugs, it will likely represent an increasing disease burden as populations age. As there are currently no pharmacological therapies available for preventing, treating, or slowing the development of CAVD, understanding the mechanisms underlying the initiation and progression of the disease is important for identifying novel therapeutic targets. Recent evidence has emerged of an important causative role for reactive oxygen species (ROS)-mediated oxidative stress in the pathophysiology of CAVD, inducing the differentiation of valve interstitial cells into myofibroblasts and then osteoblasts. In this review, we focus on the roles and sources of ROS driving CAVD and consider their potential as novel therapeutic targets for this debilitating condition.

Endothelial colony forming cells' tetrahydrobiopterin level in coronary artery disease patients and its association with circulating endothelial progenitor cells

Endothelial colony forming cells (ECFCs) participate in neovascularization. Endothelial nitric oxide synthase (eNOS) derived NO· helps in homing of endothelial progenitor cells (EPCs) at the site of vascular injury. The enzyme cofactor tetrahydrobiopterin (BH4) stabilizes the catalytic active state of eNOS. Association of intracellular ECFCs biopterins and ratio of reduced to oxidized biopterin (BH4:BH2) with circulatory EPCs and ECFCs functionality have not been studied. We investigated ECFCs biopterin levels and its association with circulatory EPCs as well as ECFCs proliferative potential in terms of day of appearance in culture. Circulatory EPCs were enumerated by flowcytometry in 53 coronary artery disease (CAD) patients and 42 controls. ECFCs were cultured, characterized, and biopterin levels assessed by high performance liquid chromatography. Appearance of ECFCs' colony and their number were recorded. Circulatory EPCs were significantly lower in CAD and ECFCs appeared in 56% and 33% of CAD and control subjects, respectively. Intracellular BH4 and BH4:BH2 were significantly reduced in CAD. BH4:BH2 was positively correlated with circulatory EPCs (p = 0.01), and negatively with day of appearance of ECFCs (p = 0.04). Circulatory EPCs negatively correlated with ECFCs appearance (p = 0.02). These findings suggest the role of biopterins in maintaining circulatory EPCs and functional integrity of ECFCs.

Diet, herbs and erectile function: A good friendship!

Plants and plant materials have been used for thousands of years to treat and control erectile dysfunction in men. This practice has spanned many cultures and traditions around the world, with the therapeutic effects of many plants attributed to their phytochemical constituents. This review explains how polyphenols (including phenolic acids, flavonoids, terpenoids, carotenoids, alkaloids and polyunsaturated fatty acids) in plants and plant food products interact with key enzymes (phosphodiesterase-5 [PDE-5], angiotensin-converting enzyme [ACE], acetylcholinesterase [AChE], adenosine deaminase [ADA] and arginase) associated with erectile dysfunction. By modulating or altering the activity of these physiologically important enzymes, various bioactive compounds from plants or plant products can synergistically or additively provide tremendous protection against male erectile problems.

No effect of acute tetrahydrobiopterin (BH4) supplementation on vascular dysfunction in the old

As a deficiency in tetrahydrobiopterin (BH4), a cofactor for endothelial nitric oxide synthase, has been implicated in the age-related decline in vascular function, this study aimed to determine the impact of acute BH4 supplementation on flow-mediated vasodilation (FMD) in old adults. Two approaches were used: 1) A multiday, double-blind, placebo-controlled, crossover design measuring, FMD [ΔFMD (mm), %FMD (%)] and shear rate area under the curve (SR AUC) in nine old subjects (73 ± 8 yr) with either placebo (placebo) or BH4 (≈10 mg/kg, post), and 2) a single experimental day measuring FMD in an additional 13 old subjects (74 ± 7 yr) prior to (pre) and 4.5 h after ingesting BH4 (≈10 mg/kg). With the first experimental approach, acute BH4 intake did not significantly alter FMD (ΔFMD: 0.17 ± 0.03 vs. 0.13 ± 0.02 mm; %FMD: 3.3 ± 0.61 vs. 2.9 ± 0.4%) or SR AUC (30,280 ± 4,428 vs. 37,877 ± 9,241 s-1) compared with placebo. Similarly, with the second approach, BH4 did not significantly alter FMD (ΔFMD: 0.09 ± 0.02 vs. 0.12 ± 0.03 mm; %FMD: 2.2 ± 0.6 vs. 2.9 ± 0.6%) or SR AUC (37,588 ± 6,753 vs. 28,996 ± 3,735 s-1) compared with pre. Moreover, when the two data sets were combined, resulting in a greater sample size, there was still no evidence of an effect of BH4 on vascular function in these old subjects. Importantly, both plasma BH4 and 7,8-dihydrobiopterin (BH2), the oxidized form of BH4, increased significantly with acute BH4 supplementation. Consequently, the ratio of BH4/BH2, recognized to impact vascular function, was unchanged. Thus, acute BH4 supplementation does not correct vascular dysfunction in the old.NEW & NOTEWORTHY Despite two different experimental approaches, acute BH4 supplementation did not affect vascular function in older adults, as measured by flow-mediated vasodilation. Plasma levels of both BH4 and BH2, the BH4 oxidized form, significantly increased after acute BH4 supplementation, resulting in an unchanged ratio of BH4/BH2, a key determining factor for endothelial nitric oxide synthase coupling. Therefore, likely due to the elevated oxidative stress with advancing age, acute BH4 supplementation does not correct vascular dysfunction in the old.

Role of endothelial colony forming cells (ECFCs) Tetrahydrobiopterin (BH4) in determining ECFCs functionality in coronary artery disease (CAD) patients

Nitric oxide (NO.) is critical for functionality of endothelial colony forming cells (ECFCs). Dimerization of endothelial nitric oxide synthase (eNOS) is must to produce NO. and tetrahydrobiopterin (BH4) plays a crucial role in stabilizing this state. We investigated BH4 level in ECFCs and its effect on ECFCs functionality in CAD patients. Intracellular biopterin levels and ECFCs functionality in terms of cell viability, adhesion, proliferation, in vitro wound healing and angiogenesis were assessed. Guanosine Triphosphate Cyclohydrolase-1 (GTPCH-1) expression was studied in ECFCs. Serum total reactive oxygen/nitrogen species was measured and effect of nitrosative stress on ECFC's biopterins level and functionality were evaluated by treating with 3-morpholino sydnonimine (SIN-1). BH4 level was significantly lower in ECFCs from CAD patients. Cell proliferation, wound closure reflecting cellular migration as well as in vitro angiogenesis were impaired in ECFCs from CAD patients. Wound healing capacity and angiogenesis were positively correlated with ECFC's BH4. A negative effect of nitrosative stress on biopterins level and cell functionality was observed in SIN-1 treated ECFCs. ECFCs from CAD exhibited impaired functionality and lower BH4 level. Association of BH4 with wound healing capacity and angiogenesis suggest its role in maintaining ECFC's functionality. Oxidative stress may be a determinant of intracellular biopterin levels.