Myeloperoxidase-derived hypochlorous acid promotes ox-LDL-induced senescence of endothelial cells through a mechanism involving β-catenin signaling in hyperlipidemia

Maintaining moderate levels of hypochlorous acid promotes neural stem cell proliferation and differentiation in the recovery phase of stroke

JOURNAL/nrgr/04.03/01300535-202503000-00029/figure1/v/2024-06-17T092413Z/r/image-tiff It has been shown clinically that continuous removal of ischemia/reperfusion-induced reactive oxygen species is not conducive to the recovery of late stroke. Indeed, previous studies have shown that excessive increases in hypochlorous acid after stroke can cause severe damage to brain tissue. Our previous studies have found that a small amount of hypochlorous acid still exists in the later stage of stroke, but its specific role and mechanism are currently unclear. To simulate stroke in vivo, a middle cerebral artery occlusion rat model was established, with an oxygen-glucose deprivation/reoxygenation model established in vitro to mimic stroke. We found that in the early stage (within 24 hours) of ischemic stroke, neutrophils produced a large amount of hypochlorous acid, while in the recovery phase (10 days after stroke), microglia were activated and produced a small amount of hypochlorous acid. Further, in acute stroke in rats, hypochlorous acid production was prevented using a hypochlorous acid scavenger, taurine, or myeloperoxidase inhibitor, 4-aminobenzoic acid hydrazide. Our results showed that high levels of hypochlorous acid (200 μM) induced neuronal apoptosis after oxygen/glucose deprivation/reoxygenation. However, in the recovery phase of the middle cerebral artery occlusion model, a moderate level of hypochlorous acid promoted the proliferation and differentiation of neural stem cells into neurons and astrocytes. This suggests that hypochlorous acid plays different roles at different phases of cerebral ischemia/reperfusion injury. Lower levels of hypochlorous acid (5 and 100 μM) promoted nuclear translocation of β-catenin. By transfection of single-site mutation plasmids, we found that hypochlorous acid induced chlorination of the β-catenin tyrosine 30 residue, which promoted nuclear translocation. Altogether, our study indicates that maintaining low levels of hypochlorous acid plays a key role in the recovery of neurological function.

Protective effects of villi mesenchymal stem cells on human umbilical vein endothelial cells by inducing SPOCD1 expression in cases of gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is characterized by a lack of response to insulin in pregnancies, and often accompanied by severe complications. GDM is associated with structural and functional alterations, particularly endothelial dysfunction, in various tissues. This study is aimed to investigate the effect of placental mesenchymal stem cells (MSCs) on the endothelial biological function of human umbilical vein endothelial cells (HUVECs) and their molecular mechanisms.

METHODS

Villi mesenchymal stem cells (VMSCs) were co-cultured with HUVECs, and transcriptomic analysis of differential genes was performed in HUVECs under high-glucose induction. Lentiviral transfection was performed to construct HUVECs with stable knockdown or overexpression of SPOCD1. The immunohistochemical assays were used to detect the expression of SPOCD1 in GDM patients. TUNEL fluorescence staining was applied for detection of the HUVEC apoptosis. β galactosidase staining assay was performed to detect the cell senescence. Electron microscopy was used to detect the cell pyroptosis. qRT-PCR and western blot assays were conducted for identifying the mRNA & protein expressions of genes.

RESULTS

VMSCs, when co-cultured with HUVECs, could inhibit the apoptosis, pyroptosis and senescence induced by high-glucose condition in HUVECs. Transcriptomic results showed an upregulation of SPOCD1 expression induced by VMSCs in HUVECs. Overexpression of SPOCD1 inhibited high-level glucose-induced apoptosis, pyroptosis and senescence in HUVECs via the β-catenin pathway.

CONCLUSION

VMSCs induce β-catenin activation by upregulating the expression of SPOCD1 in HUVECs, which ultimately inhibits high-level glucose-induced apoptosis, pyroptosis and senescence in HUVECs. This observation provides potential therapeutic insight for future GDM treatment.

Protective effect of alpha-ketoglutarate against water-immersion restraint stress-induced gastric mucosal damage in mice

Gastric lesions have several aetiologies, among which stress is the most prominent. Therefore, identification of new therapies to prevent stress is of considerable importance. Alpha-ketoglutarate (α-kg) several beneficial effects and has shown promise in combating oxidative stress, inflammation, and premature aging. Thus, this study aimed to evaluate the protective effect of α-kg in a gastric damage model by water-immersion restraint stress (WIRS). Pretreatment with α-kg decreased stress-related histopathological scores of tissue oedema, cell loss, and inflammatory infiltration. The α-kg restored the percentage of type III collagen fibres. Mucin levels were preserved as well as the structure and area of the myenteric plexus ganglia were preserved after pretreatment with α-kg. Myeloperoxidase (MPO) levels and the expression of pro-inflammatory cytokines (TNF-α and IL-1β) were also reduced following α-kg pretreatment. Decreased levels of glutathione (GSH) in the stress group were restored by α-kg. The omeprazole group was used as standard drug e also demonstrated improve on some parameters after the exposition to WIRS as inflammatory indexes, GSH and mucin. Through this, was possible to observe that α-kg can protect the gastric mucosa exposed to WIRS, preserve tissue architecture, reduce direct damage to the mucosa and inflammatory factors, stimulate the production of type III collagen and mucin, preserve the myenteric plexus ganglia, and maintain antioxidant potential. Due to, we indicate that α-kg has protective activity of the gastric mucosa, demonstrating its ability to prevent damage associated with gastric lesions caused by stress.

Efficacy and underlying mechanisms of berberine against lipid metabolic diseases: a review

Lipid-lowering therapy is an important tool for the treatment of lipid metabolic diseases, which are increasing in prevalence. However, the failure of conventional lipid-lowering drugs to achieve the desired efficacy in some patients, and the side-effects of these drug regimens, highlight the urgent need for novel lipid-lowering drugs. The liver and intestine are important in the production and removal of endogenous and exogenous lipids, respectively, and have an important impact on circulating lipid levels. Elevated circulating lipids predisposes an individual to lipid deposition in the vascular wall, affecting vascular function. Berberine (BBR) modulates liver lipid production and clearance by regulating cellular targets such as cluster of differentiation 36 (CD36), acetyl-CoA carboxylase (ACC), microsomal triglyceride transfer protein (MTTP), scavenger receptor class B type 1 (SR-BI), low-density lipoprotein receptor (LDLR), and ATP-binding cassette transporter A1 (ABCA1). It influences intestinal lipid synthesis and metabolism by modulating gut microbiota composition and metabolism. Finally, BBR maintains vascular function by targeting proteins such as endothelial nitric oxide synthase (eNOS) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). This paper elucidates and summarizes the pharmacological mechanisms of berberine in lipid metabolic diseases from a multi-organ (liver, intestine, and vascular system) and multi-target perspective.

Dyslipidemia Exacerbates Meibomian Gland Dysfunction: A Systematic Review and Meta-Analysis

Dry eye is a multifactorial and common age-related ocular surface disease. Dyslipidemia has been reported to be involved in meibomian gland dysfunction (MGD). However, it has not been clearly identified which lipid abnormality is responsible for MGD. In this systematic review and meta-analysis, we discuss how lipid profile changes with aging is responsible for MGD development.

METHODS

An article search was performed in PubMed, EMBASE, and Web of Science. Eleven studies involving dyslipidemia in patients with MGD were identified. Five out of eleven studies were further analyzed with meta-analysis. The preferred reporting items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines were followed. Study-specific estimates (prevalence of dyslipidemia in MGD patients) were combined using one-group meta-analysis in a random-effects model.

RESULTS

Meta-analysis revealed that high total cholesterol (TC) and high triglycerides (TG) were significantly associated with MGD prevalence, with odds ratios of 5.245 (95% confidence interval [CI]: 1.582-17.389; p < 0.001) and 3.264 (95% CI: 1.047-10.181; p < 0.001), respectively, but high low-density lipoprotein (LDL) and low high-density lipoprotein (HDL) were not identified. Systematic review found that the percentage of MGD patients with TC ≥ 200 mg/dL ranged from 20.0-77.6%, TG ≥ 150 mg/dL ranged from 8.3-89.7%, whereas, in the aged-match-adjusted controls, TC range of 200 mg/dL or higher and TG range of 150 mg/dL was 6.1-45.1% and 1.1-47.8%, respectively. The severity of MGD was higher with dyslipidemia.

CONCLUSION

Dyslipidemia and higher TC and TG are significant risk factors for MGD.

Therapeutic opportunities for senolysis in cardiovascular disease

Cellular senescence within the cardiovascular system has, until recently, been understudied and unappreciated as a factor in the development of age-related cardiovascular diseases such as heart failure, myocardial infarction and atherosclerosis. This is in part due to challenges with defining senescence within post-mitotic cells such as cardiomyocytes. However, recent evidence has demonstrated senescent-like changes, including a senescence-associated secretory phenotype (SASP), in cardiomyocytes in response to ageing and cell stress. Other replicating cells, including fibroblasts and vascular smooth muscle cells, within the cardiovascular system have also been shown to undergo senescence and contribute to disease pathogenesis. These findings coupled with the emergence of senolytic therapies, to target and eliminate senescent cells, have provided fascinating new avenues for management of several age-related cardiovascular diseases with high prevalence. In this review, we discuss the role of senescent cells within the cardiovascular system and highlight the contribution of senescence cells to common cardiovascular diseases. We discuss the emerging role for senolytics in cardiovascular disease management while highlighting important aspects of senescence biology which must be clarified before the potential of senolytics can be fully realized.

A Unified Model of Age-Related Cardiovascular Disease

Despite progress in biomedical technologies, cardiovascular disease remains the main cause of mortality. This is at least in part because current clinical interventions do not adequately take into account aging as a driver and are hence aimed at suboptimal targets. To achieve progress, consideration needs to be given to the role of cell aging in disease pathogenesis. We propose a model unifying the fundamental processes underlying most age-associated cardiovascular pathologies. According to this model, cell aging, leading to cell senescence, is responsible for tissue changes leading to age-related cardiovascular disease. This process, occurring due to telomerase inactivation and telomere attrition, affects all components of the cardiovascular system, including cardiomyocytes, vascular endothelial cells, smooth muscle cells, cardiac fibroblasts, and immune cells. The unified model offers insights into the relationship between upstream risk factors and downstream clinical outcomes and explains why interventions aimed at either of these components have limited success. Potential therapeutic approaches are considered based on this model. Because telomerase activity can prevent and reverse cell senescence, telomerase gene therapy is discussed as a promising intervention. Telomerase gene therapy and similar systems interventions based on the unified model are expected to be transformational in cardiovascular medicine.

Myeloperoxidase: Regulation of Neutrophil Function and Target for Therapy

Neutrophils, the most abundant white blood cells in humans, are critical for host defense against invading pathogens. Equipped with an array of antimicrobial molecules, neutrophils can eradicate bacteria and clear debris. Among the microbicide proteins is the heme protein myeloperoxidase (MPO), stored in the azurophilic granules, and catalyzes the formation of the chlorinating oxidant HOCl and other oxidants (HOSCN and HOBr). MPO is generally associated with killing trapped bacteria and inflicting collateral tissue damage to the host. However, the characterization of non-enzymatic functions of MPO suggests additional roles for this protein. Indeed, evolving evidence indicates that MPO can directly modulate the function and fate of neutrophils, thereby shaping immunity. These actions include MPO orchestration of neutrophil trafficking, activation, phagocytosis, lifespan, formation of extracellular traps, and MPO-triggered autoimmunity. This review scrutinizes the multifaceted roles of MPO in immunity, focusing on neutrophil-mediated host defense, tissue damage, repair, and autoimmunity. We also discuss novel therapeutic approaches to target MPO activity, expression, or MPO signaling for the treatment of inflammatory and autoimmune diseases.

Artificial neuronal network analysis in investigating the relationship between oxidative stress and endoplasmic reticulum stress to address blocked vessels in cardiovascular disease

BACKGROUND

Cardiovascular disease is the leading cause of death in the world and is associated with significant morbidity. Atherosclerosis is the main cause of cardiovascular disease (CVD), including myocardial infarction (MI), heart failure, and stroke. The mechanism of atherosclerosis has not been well investigated in different aspects, such as the relationship between oxidative stress and endothelial function. This project aims to investigate whether an oxidative enzyme vascular peroxidase 1 (VPO1) and activating transcription factor 4 (ATF4) can be used as biomarkers in highlighting the pathogenesis of the disease and in evaluating the prognosis of the relationship with endoplasmic reticulum and oxidative stress. This paper used artificial neural network analysis to predict cardiovascular disease risk based on new generation biochemical markers that combine vascular inflammation, oxidative and endoplasmic reticulum stress.

METHODS

For this purpose, 80 patients were evaluated according to the coronary angiography results. hs-CRP, lipid parameters and demographic characteristics, VPO1, ATF4 and Glutathione peroxidase 1(GPx1) levels were measured.

RESULTS

We found an increase in VPO1 and hs-CRP levels in single-vessel disease as compared to controls. On the contrary, ATF4 and GPx1 levels were decreased in the same group, which was not significant. Our results showed a significant positive correlation between ATF4 and lipid parameters. A statistically significant positive correlation was also observed for VPO1 and ATF4 (r=0.367, P<0.05), and a negative correlation was found for ATF4 and GPx1 (r=-0.467, P<0.01). A significant negative relationship was noted for GPx1 and hs-CRP in two/three-vessel disease (r=-0.366, P<0.05). Artificial neural network analysis stated that body mass index (BMI) and smoking history information give us an important clue as compared to age, gender and alcohol consumption parameters when predicting the number of blocked vessels.

CONCLUSIONS

VPO1 and ATF4 might be potential biomarkers associated with coronary artery disease, especially in the follow-up and monitoring of treatment protocols, in addition to traditional risk factors.

Zingiber officinale and Vernonia amygdalina Infusions Improve Redox Status in Rat Brain

The study investigated the effects of Zingiber officinale root and Vernonia amygdalina leaf on the brain redox status of Wistar rats. Twenty-four (24) rats weighing 160 ± 20 g were randomly assigned into four (4) groups, each with six (6) rats. Animals in Group 1 (control) were orally administered distilled water (1 mL), while the test groups were orally administered 5 mg/mL of either Z. officinale, V. amygdalina infusion, or a combination of both, respectively, for 7 days. The rats were sacrificed at the end of treatments and blood and tissue were harvested and prepared for biochemical assays. Results showed that administration of V. amygdalina and Z. officinale, as well as their coadministration, reduced the levels of malondialdehyde (MDA), nitric oxide (NO), acetylcholinesterase (AChE), and myeloperoxidase (MPO) in rat brain tissue compared with the control group. Conversely, coadministration of V. amygdalina and Z. officinale increased the levels of reduced glutathione (GSH) in rat brain tissue compared with the control group. However, the administration of the infusions singly, as well as the combination of both infusions, did not have any effect on the rat brain levels of glutathione peroxidase (GPx) and catalase (CAT) antioxidant enzymes compared to the control. Taken together, the findings indicate that the V. amygdalina and Z. officinale tea infusions have favorable antioxidant properties in the rat brain. The findings are confirmatory and contribute to deepening our understanding of the health-promoting effects of V. amygdalina and Z. officinale tea infusions.

Epidermal Immunity and Function: Origin in Neonatal Skin

The fascinating story of epidermal immunity begins in utero where the epidermal barrier derives from the ectoderm and evolves through carefully orchestrated biological processes, including periderm formation, keratinocyte differentiation, proliferation, cornification, and maturation, to generate a functional epidermis. Vernix caseosa derives from epidermal cells that mix with sebaceous lipids and coat the fetus during late gestation, likely to provide conditions for cornification. At birth, infants dramatically transition from aqueous conditions to a dry gaseous environment. The epidermal barrier begins to change within hours, exhibiting decreased hydration and low stratum corneum (SC) cohesion. The SC varied by gestational age (GA), transformed over the next 2–3 months, and differed considerably versus stable adult skin, as indicated by analysis of specific protein biomarkers. Regardless of gestational age, the increased infant SC proteins at 2–3 months after birth were involved in late differentiation, cornification, and filaggrin processing compared to adult skin. Additionally, the natural moisturizing factor (NMF), the product of filaggrin processing, was higher for infants than adults. This suggests that neonatal skin provides innate immunity and protection from environmental effects and promotes rapid, continued barrier development after birth. Functional genomic analysis showed abundant differences across biological processes for infant skin compared to adult skin. Gene expression for extracellular matrix, development, and fatty acid metabolism was higher for infant skin, while adult skin had increased expression of genes for the maintenance of epidermal homeostasis, antigen processing/presentation of immune function, and others. These findings provide descriptive information about infant epidermal immunity and its ability to support the newborn’s survival and growth, despite an environment laden with microbes, high oxygen tension, and irritants.

New insight into dyslipidemia‐induced cellular senescence in atherosclerosis

Atherosclerosis, characterized by lipid‐rich plaques in the arterial wall, is an age‐related disorder and a leading cause of mortality worldwide. However, the specific mechanisms remain complex. Recently, emerging evidence has demonstrated that senescence of various types of cells, such as endothelial cells (ECs), vascular smooth muscle cells (VSMCs), macrophages, endothelial progenitor cells (EPCs), and adipose‐derived mesenchymal stem cells (AMSCs) contributes to atherosclerosis. Cellular senescence and atherosclerosis share various causative stimuli, in which dyslipidemia has attracted much attention. Dyslipidemia, mainly referred to elevated plasma levels of atherogenic lipids or lipoproteins, or functional impairment of anti‐atherogenic lipids or lipoproteins, plays a pivotal role both in cellular senescence and atherosclerosis. In this review, we summarize the current evidence for dyslipidemia‐induced cellular senescence during atherosclerosis, with a focus on low‐density lipoprotein (LDL) and its modifications, hydrolysate of triglyceride‐rich lipoproteins (TRLs), and high‐density lipoprotein (HDL), respectively. Furthermore, we describe the underlying mechanisms linking dyslipidemia‐induced cellular senescence and atherosclerosis. Finally, we discuss the senescence‐related therapeutic strategies for atherosclerosis, with special attention given to the anti‐atherosclerotic effects of promising geroprotectors as well as anti‐senescence effects of current lipid‐lowering drugs.

Unexpected Role of MPO-Oxidized LDLs in Atherosclerosis: In between Inflammation and Its Resolution

Inflammation and its resolution are the result of the balance between pro-inflammatory and pro-resolving factors, such as specialized pro-resolving mediators (SPMs). This balance is crucial for plaque evolution in atherosclerosis, a chronic inflammatory disease. Myeloperoxidase (MPO) has been related to oxidative stress and atherosclerosis, and MPO-oxidized low-density lipoproteins (Mox-LDLs) have specific characteristics and effects. They participate in foam cell formation and cause specific reactions when interacting with macrophages and endothelial cells. They also increase the production of intracellular reactive oxygen species (ROS) in macrophages and the resulting antioxidant response. Mox-LDLs also drive macrophage polarization. Mox-LDLs are known to be pro-inflammatory particles. However, in the presence of Mox-LDLs, endothelial cells produce resolvin D1 (RvD1), a SPM. SPMs are involved in the resolution of inflammation by stimulating efferocytosis and by reducing the adhesion and recruitment of neutrophils and monocytes. RvD1 also induces the synthesis of other SPMs. In vitro, Mox-LDLs have a dual effect by promoting RvD1 release and inducing a more anti-inflammatory phenotype macrophage, thereby having a mixed effect on inflammation. In this review, we discuss the interrelationship between MPO, Mox-LDLs, and resolvins, highlighting a new perception of the role of Mox-LDLs in atherosclerosis.

Critical Computational Evidence Regarding the Long-Standing Controversy Over the Main Electrophilic Species in Hypochlorous Acid Solution

Although hypochlorous acid (HOCl) solution has become a popular electrophilic reagent for industrial uses, the question of which molecule (HOCl or Cl₂) undergoes electrophilic addition with olefins remains a controversial issue in some literature and textbooks, and this problem has been largely underexplored in theoretical studies. In this work, we computationally studied the electrophilic addition mechanism of olefins using three experimentally predicted effective electrophilic chlorinating agents, i.e., HOCl, Cl₂, and Cl₂O molecules. Our results demonstrate that Cl₂ and Cl₂O are the main electrophilic agents in HOCl solution, whereas the HOCl molecule cannot be the electrophile since the energy barrier when directly adding HOCl molecule to olefins is too high to overcome and the “anti-Markovnikov” regioselectivity for tri-substituted olefin is not consistent with experiments. Notably, the HOCl molecule prefers to form oxonium ion intermediate with a double bond, rather than the generally believed chlorium ion intermediate. This work could benefit mechanistic studies of critical biological and chemical processes with HOCl solution and may be used to update textbooks.

Investigation of the impact caused by different sizes of polyethylene plastics (nano, micro, and macro) in common carp juveniles, Cyprinus carpio L., using multi-biomarkers

Plastic pollution poses a global threat to aquatic organisms, yet its effect on many species remains poorly documented and understood. This study addresses the impact caused by different sizes of polyethylene (PE) plastics on the common carp and evaluates their multi-biomarkers response. We investigated the histological structure and measurement of biochemical alterations, antioxidant enzymes, immunological responses, and fluctuations in blood profiles of the organisms after 15 days of exposure to a concentration of 100 mg/L of nano- (NPs), micro- (MPs) and macroplastics (MaPs). The fish health status was altered in the sole presence of PE particles. All biomarkers changed after exposure compared to the control group, with larger changes being observed with the decreasing size of particles (NPs > MPs > MaPs) compared to their absence. A synergistic effect resulting from the individual impact of plastics penetration in the circulatory system, bursting biochemical responses, and lesions in tissues, might explain the more considerable impact of NPs compared to MPs and/or MaPs.

A Review of Novel Cardiac Biomarkers in Acute or Chronic Cardiovascular Diseases: The Role of Soluble ST2 (sST2), Lipoprotein-Associated Phospholipase A2 (Lp-PLA2), Myeloperoxidase (MPO), and Procalcitonin (PCT)

While the received traditional predictors are still the mainstay in the diagnosis and prognosis of CVD events, increasing studies have focused on exploring the ancillary effect of biomarkers for the aspiring of precision. Under which circumstances, soluble ST2 (sST2), lipoprotein-associated phospholipase A2 (Lp-PLA2), myeloperoxidase (MPO), and procalcitonin (PCT) have recently emerged as promising markers in the field of both acute and chronic cardiovascular diseases. Existent clinical studies have demonstrated the significant associations between these markers with various CVD outcomes, which further verified the potentiality of markers in helping risk stratification and diagnostic and therapeutic work-up of patients. The current review article is aimed at illuminating the applicability of these four novels and often neglected cardiac biomarkers in common clinical scenarios, including acute myocardial infarction, acute heart failure, and chronic heart failure, especially in the emergency department. By thorough classification, combination, and discussion of biomarkers with clinical and instrumental evaluation, we hope the current study can provide insights into biomarkers and draw more attention to their importance.

Myeloperoxidase Inhibition Decreases the Expression of Collagen and Metallopeptidase in Mare Endometria under In Vitro Conditions

Neutrophils can originate neutrophil extracellular traps (NETs). Myeloperoxidase (MPO) is a peroxidase found in NETs associated to equine endometrosis and can be inhibited by 4-aminobenzoic acid hydrazide (ABAH). Metallopeptidases (MMPs) participate in extracellular matrix stability and fibrosis development. The objectives of this in vitro work were to investigate, in explants of mare's endometrium, (i) the ABAH capacity to inhibit MPO-induced collagen type I (COL1) expression; and (ii) the action of MPO and ABAH on the expression and gelatinolytic activity of MMP-2/-9. Explants retrieved from the endometrium of mares in follicular or mid-luteal phases were treated with MPO, ABAH, or their combination, for 24 or 48 h. The qPCR analysis measured the transcription of COL1A2, MMP2, and MMP9. Western blot and zymography were performed to evaluate COL1 protein relative abundance and gelatinolytic activity of MMP-2/-9, respectively. Myeloperoxidase elevated COL1 relative protein abundance at both treatment times in follicular phase (p < 0.05). The capacity of ABAH to inhibit MPO-induced COL1 was detected in follicular phase at 48 h (p < 0.05). The gelatinolytic activity of activated MMP-2 augmented in mid-luteal phase at 24 h after MPO treatment, but it was reduced with MPO+ABAH treatment. The activity of MMP-9 active form augmented in MPO-treated explants. However, this effect was inhibited by ABAH in the follicular phase at 48 h (p < 0.05). By inhibiting the pro-fibrotic effects of MPO, it might be possible to reduce the development of endometrosis. Metallopeptidase-2 might be involved in an acute response to MPO in the mid-luteal phase, while MMP-9 might be implicated in a prolonged exposition to MPO in the follicular phase.

Inhibition of Myeloperoxidase

Myeloperoxidase participates in innate immune defense mechanism through formation of microbicidal reactive oxidants and diffusible radical species. A unique activity is its ability to use chloride as a cosubstrate with hydrogen peroxide to generate chlorinating oxidants such as hypochlorous acid, a potent antimicrobial agent. However, chronic MPO activation can lead to indiscriminate protein modification causing tissue damage, and has been associated with chronic inflammatory diseases, atherosclerosis, and acute cardiovascular events. This has attracted considerable interest in the development of therapeutically useful MPO inhibitors. Today, based on the profound knowledge of structure and function of MPO and its biochemical and biophysical differences with the other homologous human peroxidases, various rational and high-throughput screening attempts were performed in developing specific irreversible and reversible inhibitors. The most prominent candidates as well as MPO inhibitors already studied in clinical trials are introduced and discussed.

Methoxyphenol derivatives as reversible inhibitors of myeloperoxidase as potential antiatherosclerotic agents

Aim: To evaluate new chemical entities, based on ferulic acid scaffolds, as reversible myeloperoxidase inhibitors (MPOI). Methodology & results:In silico docking studies are performed with MPO protein as a target for several ferulic acid analogs followed by multiple in vitro assays to validate this approach. Two lead compounds 2a and 3 are identified with optimum docking and IC50 values: -7.95 kcal/mol, 0.9 μM and -8.35 kcal/mol, 8.5 μM, respectively. These MPOIs are able to inhibit oxidation of high-density lipoprotein and further promoted functionality of high-density lipoprotein. Conclusion: Lead analogs are potent MPOIs that exert specific effects on MPO-mediated oxidation as well as inflammatory pathways. It also acts as promoters of cholesterol efflux that sheds light on pharmacological approach in atherosclerosis treatment.

Mulberry Extract Attenuates Endothelial Dysfunction through the Regulation of Uncoupling Endothelial Nitric Oxide Synthase in High Fat Diet Rats

Dyslipidemia is associated with endothelial dysfunction, which is linked to nitric oxide (NO) biology. The coupling of endothelial NO synthase with cofactors is a major step for NO release. This study is aimed to investigate the vascular pharmacology effects of mulberry in rat thoracic aorta and human vascular endothelial cells. In vitro, we investigated the protective effects of the mulberry extract and its main component cyanidin-3-rutinoside (C-3-R), against oxidized low-density lipoprotein (ox-LDL)-induced endothelial nitric oxide synthase (eNOS) uncoupling. Whereas ox-LDL significantly decreased NO levels in endothelial cells, mulberry extract, and C-3-R significantly recovered NO levels and phospho-eNOS Thr495 and Ser1177 expression. In vivo, mulberry was administered to 60% of high-fat diet (w/w)-fed Sprague Dawley (SD) rats for six weeks, in which endothelium-dependent relaxations were significantly improved in organ bath studies and isometric tension recordings. Consistently, aortic expressions of phospho-eNOS and nitrotyrosine were increased. Mulberry also raised serum NO levels, increased phosphorylation of eNOS, and reduced nitrotyrosine and intracellular reactive oxygen species (ROS) in aortas, showing that mulberry preserves endothelium-dependent relaxation in aortas from high-fat diet rats. We suggest that this effect is mediated through enhanced NO bioavailability, in which the regulation of ROS and its reduced eNOS uncoupling are involved.

p53 plays a crucial role in endothelial dysfunction associated with hyperglycemia and ischemia

p53 is a guardian of the genome that protects against carcinogenesis. There is accumulating evidence that p53 is activated with aging. Such activation has been reported to contribute to various age-associated pathologies, but its role in vascular dysfunction is largely unknown. The aim of this study was to investigate whether activation of endothelial p53 has a pathological effect in relation to endothelial function. We established endothelial p53 loss-of-function and gain-of-function models by breeding endothelial-cell specific Cre mice with floxed Trp53 or floxed Mdm2/Mdm4 mice, respectively. Then we induced diabetes by injection of streptozotocin. In the diabetic state, endothelial p53 expression was markedly up-regulated and endothelium-dependent vasodilatation was significantly impaired. Impairment of vasodilatation was significantly ameliorated in endothelial p53 knockout (EC-p53 KO) mice, and deletion of endothelial p53 also significantly enhanced the induction of angiogenesis by ischemia. Conversely, activation of endothelial p53 by deleting Mdm2/Mdm4 reduced both endothelium-dependent vasodilatation and ischemia-induced angiogenesis. Introduction of p53 into human endothelial cells up-regulated the expression of phosphatase and tensin homolog (PTEN), thereby reducing phospho-eNOS levels. Consistent with these results, the beneficial impact of endothelial p53 deletion on endothelial function was attenuated in EC-p53 KO mice with an eNOS-deficient background. These results show that endothelial p53 negatively regulates endothelium-dependent vasodilatation and ischemia-induced angiogenesis, suggesting that inhibition of endothelial p53 could be a novel therapeutic target in patients with metabolic disorders.

NLRP3 Deficiency Alleviates Severe Acute Pancreatitis and Pancreatitis-Associated Lung Injury in a Mouse Model

The rapid production and release of a large number of inflammatory cytokines can cause excessive local and systemic inflammation in severe acute pancreatitis (SAP) and multiple organ dysfunction syndrome (MODS), especially pancreatitis-associated acute lung injury (P-ALI), which is the main cause of early death in patients with SAP. The NLRP3 inflammasome plays an important role in the maturation of IL-1β and the inflammatory cascade. Here, we established a model of SAP using wild-type (NLRP3^+/+) and NLRP3 knockout (NLRP3^−/−) mice by intraperitoneal injections of caerulein (Cae) and lipopolysaccharide (LPS). Pathological injury to the pancreas and lungs, the inflammatory response, and neutrophil infiltration were significantly mitigated in NLRP3^−/− mice. Furthermore, INF-39, an NLRP3 inflammasome inhibitor, could reduce the severity of SAP and P-ALI in a dose-dependent manner. Our results suggested that SAP and P-ALI were alleviated by NLRP3 deficiency in mice, and thus, reducing NLRP3 expression may mitigate SAP-associated inflammation and P-ALI.

Obesity and type-2 diabetes as inducers of premature cellular senescence and ageing

Cellular senescence is now considered as a major mechanism in the development and progression of various diseases and this may include metabolic diseases such as obesity and type-2 diabetes. The presence of obesity and diabetes is a major risk factor in the development of additional health conditions, such as cardiovascular disease, kidney disease and cancer. Since senescent cells can drive disease development, obesity and diabetes can potentially create an environment that accelerates cell senescence within other tissues of the body. This can consequently manifest as age-related biological impairments and secondary diseases. Cell senescence in cell types linked with obesity and diabetes, namely adipocytes and pancreatic beta cells will be explored, followed by a discussion on the role of obesity and diabetes in accelerating ageing through induction of premature cell senescence mediated by high glucose levels and oxidised low-density lipoproteins. Particular emphasis will be placed on accelerated cell senescence in endothelial progenitor cells, endothelial cells and vascular smooth muscle cells with relation to cardiovascular disease and proximal tubular cells with relation to kidney disease. A summary of the potential strategies for therapeutically targeting senescent cells for improving health is also presented.

Myeloperoxidase as an Active Disease Biomarker: Recent Biochemical and Pathological Perspectives

Myeloperoxidase (MPO) belongs to the family of heme-containing peroxidases, produced mostly from polymorphonuclear neutrophils. The active enzyme (150 kDa) is the product of the MPO gene located on long arm of chromosome 17. The primary gene product undergoes several modifications, such as the removal of introns and signal peptides, and leads to the formation of enzymatically inactive glycosylated apoproMPO which complexes with chaperons, producing inactive proMPO by the insertion of a heme moiety. The active enzyme is a homodimer of heavy and light chain protomers. This enzyme is released into the extracellular fluid after oxidative stress and different inflammatory responses. Myeloperoxidase is the only type of peroxidase that uses H₂O₂ to oxidize several halides and pseudohalides to form different hypohalous acids. So, the antibacterial activities of MPO involve the production of reactive oxygen and reactive nitrogen species. Controlled MPO release at the site of infection is of prime importance for its efficient activities. Any uncontrolled degranulation exaggerates the inflammation and can also lead to tissue damage even in absence of inflammation. Several types of tissue injuries and the pathogenesis of several other major chronic diseases such as rheumatoid arthritis, cardiovascular diseases, liver diseases, diabetes, and cancer have been reported to be linked with MPO-derived oxidants. Thus, the enhanced level of MPO activity is one of the best diagnostic tools of inflammatory and oxidative stress biomarkers among these commonly-occurring diseases.

Suppression of NADPH oxidase attenuates hypoxia-induced dysfunctions of endothelial progenitor cells

NADPH oxidases (NOX) - derived reactive oxygen species (ROS) contribute to oxidative injury in hypoxia-induced pulmonary arterial hypertension. This study aims to evaluate the status of NOX in endothelial progenitor cells (EPCs) under hypoxic condition and to determine whether NOX inhibitors could attenuate hypoxia-induced dysfunctions of EPCs. EPCs were isolated from peripheral blood of SD rats and subjected to hypoxia (O₂/N₂/CO₂, 1/94/5) for 24 h. The cells were collected for β-galactosidase or Hoechst staining, or for functional analysis (migration, adhesion and tube formation). The NOX expression, activity and H₂O₂ content in EPCs were measured. The results showed that hypoxia treatment promoted EPC senescence and apoptosis, accompanied by the deteriorated functions of EPCs (the reduced abilities in adhesion, migration and tube formation), as well as an increase in NOX2 and NOX4 expression, NOX activity and H₂O₂ production, these phenomena were attenuated by NOX inhibitors. Furthermore, administration of catalase could also improve the functions of hypoxia-treated EPCs. Based on these observations, we conclude that NOX-derived ROS contributes to the dysfunctions of EPCs under hypoxic condition. Thus, suppression of NOX may provide a novel strategy to improve endothelial functions in hypoxia-relevant diseases.

A dinuclear ruthenium(II) complex as turn-on luminescent probe for hypochlorous acid and its application for in vivo imaging

A dinuclear ruthenium(II) complex Ruazo was designed and synthesized, in which oxidative cyclization of the azo and o-amino group was employed for the detection of hypochlorous acid (HClO) in aqueous solution. The non-emissive Ruazo formed highly luminescent triazole-ruthenium(II) complex in presence of HClO and successfully imaged HClO in living cell and living mouse.