Heme oxygenase-1 ameliorates oxidative stress-induced endothelial senescence via regulating endothelial nitric oxide synthase activation and coupling

Anti‑inflammatory effects of methanol extract from Peperomia dindygulensis Miq. mediated by HO‑1 in LPS‑induced RAW 264.7 cells

Inflammation serves as a multifaceted defense mechanism activated by pathogens, cellular damage and irritants, aiming to eliminate primary causes of injury and promote tissue repair. Peperomia dindygulensis Miq. (P. dindygulensis), prevalent in Vietnam and southern China, has a history of traditional use for treating cough, fever and asthma. Previous studies on its phytochemicals have shown their potential as anti-inflammatory agents, yet underlying mechanisms remain to be elucidated. The present study investigated the regulatory effects of P. dindygulensis on the anti-inflammatory pathways. The methanol extracts of P. dindygulensis (PDME) were found to inhibit nitric oxide (NO) production and induce heme oxygenase-1 (HO-1) expression in murine macrophages. While MAPKs inhibitors, such as SP600125, SB203580 and U0126 did not regulate HO-1 expression, the treatment of cycloheximide, a translation inhibitor, reduced HO-1. Furthermore, PDME inhibited lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and TNF-α expression at both the mRNA and protein levels. The activity of NOS and the expression of TNF-α, iNOS and COX-2 decreased in LPS-stimulated Raw 264.7 cells treated with PDME and this effect was regulated by inhibition of HO-1 activity. These findings suggested that PDME functions as an HO-1 inducer and serves as an effective natural anti-inflammatory agent in LPS-induced inflammation.

Eicosapentaenoic Acid Improves Endothelial Nitric Oxide Bioavailability Via Changes in Protein Expression During Inflammation

BACKGROUND

Endothelial cell (EC) dysfunction involves reduced nitric oxide (NO) bioavailability due to NO synthase uncoupling linked to increased oxidation and reduced cofactor availability. Loss of endothelial function and NO bioavailability are associated with inflammation, including leukocyte activation. Eicosapentaenoic acid (EPA) administered as icosapent ethyl reduced cardiovascular events in REDUCE-IT (Reduction of Cardiovascular Events With Icosapent Ethyl-Intervention Trial) in relation to on-treatment EPA blood levels. The mechanisms of cardiovascular protection for EPA remain incompletely elucidated but likely involve direct effects on the endothelium.

METHODS AND RESULTS

In this study, human ECs were treated with EPA and challenged with the cytokine IL-6 (interleukin-6). Proinflammatory responses in the ECs were confirmed by ELISA capture of sICAM-1 (soluble intercellular adhesion molecule-1) and TNF-α (tumor necrosis factor-α). Global protein expression was determined using liquid chromatography-mass spectrometry tandem mass tag. Release kinetics of NO and peroxynitrite were monitored using porphyrinic nanosensors. IL-6 challenge induced proinflammatory responses from the ECs as evidenced by increased release of sICAM-1 and TNF-α, which correlated with a loss of NO bioavailability. ECs pretreated with EPA modulated expression of 327 proteins by >1-fold (P<0.05), compared with IL-6 alone. EPA augmented expression of proteins involved in NO production, including heme oxygenase-1 and dimethylarginine dimethylaminohydrolase-1, and 34 proteins annotated as associated with neutrophil degranulation. EPA reversed the endothelial NO synthase uncoupling induced by IL-6 as evidenced by an increased [NO]/[peroxynitrite] release ratio (P<0.05).

CONCLUSIONS

These direct actions of EPA on EC functions during inflammation may contribute to its distinct cardiovascular benefits.

A non-canonical role of ELN protects from cellular senescence by limiting iron-dependent regulation of gene expression

The ELN gene encodes tropoelastin which is used to generate elastic fibers that insure proper tissue elasticity. Decreased amounts of elastic fibers and/or accumulation of bioactive products of their cleavage, named elastokines, are thought to contribute to aging. Cellular senescence, characterized by a stable proliferation arrest and by the senescence-associated secretory phenotype (SASP), increases with aging, fostering the onset and progression of age-related diseases and overall aging, and has so far never been linked with elastin. Here, we identified that decrease in ELN either by siRNA in normal human fibroblasts or by knockout in mouse embryonic fibroblasts results in premature senescence. Surprisingly this effect is independent of elastic fiber degradation or elastokines production, but it relies on the rapid increase in HMOX1 after ELN downregulation. Moreover, the induction of HMOX1 depends on p53 and NRF2 transcription factors, and leads to an increase in iron, further mediating ELN downregulation-induced senescence. Screening of iron-dependent DNA and histones demethylases revealed a role for histone PHF8 demethylase in mediating ELN downregulation-induced senescence. Collectively, these results unveil a role for ELN in protecting cells from cellular senescence through a non-canonical mechanism involving a ROS/HMOX1/iron accumulation/PHF8 histone demethylase pathway reprogramming gene expression towards a senescence program.

Heme oxygenase 1 (HO1) regulates autophagy and apoptosis via the PI3K/AKT/mTOR signaling pathway of yak Sertoli cells

Successful male reproduction depends on healthy testes. Autophagy has been confirmed to be active during many cellular events associated with the testes. It is not only crucial for testicular spermatogenesis but is also an essential regulatory mechanism for Sertoli cell (SCs) ectoplasmic specialization integrity and normal function of the blood-testis-barrier. Hypoxic stress induces oxidative damage, apoptosis, and autophagy, negatively affecting the male reproductive system. Cryptorchidism is a common condition associated with infertility. Recent studies have demonstrated that hypoxia-induced miRNAs and their transcription factors are highly expressed in the testicular tissue of infertile patients. Heme oxygenase 1 (HO1) is a heat-shock protein family member associated with cellular antioxidant defense and anti-apoptotic functions. The present study found that the HO1 mRNA and protein are up-regulated in yak cryptorchidism compared to normal testes. Next, we investigated the expression of HO1 in the SCs exposed to hypoxic stress and characterized the expression of key molecules involved in autophagy and apoptosis. The results showed that hypoxic stress induced the upregulation of autophagy of SCs. The down-regulation of HO1 using siRNA increases autophagy and decreases apoptosis, while the over-expression of HO1 attenuates autophagy and increases apoptosis. Furthermore, HO1 regulates autophagy and apoptosis via the PI3K/AKT/mTOR signaling pathway. These results will be helpful for further understanding the regulatory mechanisms of HO1 in yak cryptorchidism.

Stem cell-derived vessels-on-chip for cardiovascular disease modeling

The metabolic syndrome is accompanied by vascular complications. Human in vitro disease models are hence required to better understand vascular dysfunctions and guide clinical therapies. Here, we engineered an open microfluidic vessel-on-chip platform that integrates human pluripotent stem cell-derived endothelial cells (SC-ECs). The open microfluidic design enables seamless integration with state-of-the-art analytical technologies, including single-cell RNA sequencing, proteomics by mass spectrometry, and high-resolution imaging. Beyond previous systems, we report SC-EC maturation by means of barrier formation, arterial toning, and high nitric oxide synthesis levels under gravity-driven flow. Functionally, we corroborate the hallmarks of early-onset atherosclerosis with low sample volumes and cell numbers under flow conditions by determining proteome and secretome changes in SC-ECs stimulated with oxidized low-density lipoprotein and free fatty acids. More broadly, our organ-on-chip platform enables the modeling of patient-specific human endothelial tissue and has the potential to become a general tool for animal-free vascular research.

Do patients benefit from omega-3 fatty acids?

Omega-3 fatty acids (O3FAs) possess beneficial properties for cardiovascular (CV) health and elevated O3FA levels are associated with lower incident risk for CV disease (CVD.) Yet, treatment of at-risk patients with various O3FA formulations has produced disparate results in large, well-controlled and well-conducted clinical trials. Prescription formulations and fish oil supplements containing low-dose mixtures of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have routinely failed to prevent CV events in primary and secondary prevention settings when added to contemporary care, as shown most recently in the STRENGTH and OMEMI trials. However, as observed in JELIS, REDUCE-IT, and RESPECT-EPA, EPA-only formulations significantly reduce CVD events in high-risk patients. The CV mechanism of action of EPA, while certainly multifaceted, does not depend solely on reductions of circulating lipids, including triglycerides (TG) and LDL, and event reduction appears related to achieved EPA levels suggesting that the particular chemical and biological properties of EPA, as compared to DHA and other O3FAs, may contribute to its distinct clinical efficacy. In vitro and in vivo studies have shown different effects of EPA compared with DHA alone or EPA/DHA combination treatments, on atherosclerotic plaque morphology, LDL and membrane oxidation, cholesterol distribution, membrane lipid dynamics, glucose homeostasis, endothelial function, and downstream lipid metabolite function. These findings indicate that prescription-grade, EPA-only formulations provide greater benefit than other O3FAs formulations tested. This review summarizes the clinical findings associated with various O3FA formulations, their efficacy in treating CV disease, and their underlying mechanisms of action.

Astragalus polysaccharides attenuate rat aortic endothelial senescence via regulation of the SIRT-1/p53 signaling pathway

BACKGROUND

Astragalus polysaccharides (APS) have been verified to have antioxidative and antiaging activities in the mouse liver and brain. However, the effect of APS on aortic endothelial senescence in old rats and its underlying mechanism are currently unclear. Here, we aimed to elucidate the effects of APS on rat aortic endothelial oxidative stress and senescence in vitro and in vivo and investigate the potential molecular targets.

METHODS

Twenty-month-old natural aging male rats were treated with APS (200 mg/kg, 400 mg/kg, 800 mg/kg daily) for 3 months. Serum parameters were tested using corresponding assay kits. Aortic morphology was observed by staining with hematoxylin and eosin (H&E) and Verhoeff Van Gieson (VVG). Aging-related protein levels were evaluated using immunofluorescence and western blot analysis. Primary rat aortic endothelial cells (RAECs) were isolated by tissue explant method. RAEC mitochondrial function was evaluated by the mitochondrial membrane potential (MMP) measured with the fluorescent lipophilic cationic dye JC‑1. Intracellular total antioxidant capacity (T-AOC) was detected by a commercial kit. Cellular senescence was assessed using senescence-associated-β-galactosidase (SA-β-Gal) staining.

RESULTS

Treatment of APS for three months was found to lessen aortic wall thickness, renovate vascular elastic tissue, improve vascular endothelial function, and reduce oxidative stress levels in 20-month-old rats. Primary mechanism analysis showed that APS treatment enhanced Sirtuin 1 (SIRT-1) protein expression and decreased the levels of the aging marker proteins p53, p21 and p16 in rat aortic tissue. Furthermore, APS abated hydrogen peroxide (H2O2)-induced cell senescence and restored H2O2-induced impairment of the MMP and T-AOC in RAECs. Similarly, APS increased SIRT-1 and decreased p53, p21 and p16 protein levels in senescent RAECs isolated from old rats. Knockdown of SIRT-1 diminished the protective effect of APS against H2O2-induced RAEC senescence and T-AOC loss, increased the levels of the downstream proteins p53 and p21, and abolished the inhibitory effect of APS on the expression of these proteins in RAECs.

CONCLUSION

APS may reduce rat aortic endothelial oxidative stress and senescence via the SIRT-1/p53 signaling pathway.

RAD54B inhibits vascular endothelial senescence via suppression of CHK1/p53/p21 pathway

RAD54B belongs to the SNF2/SWI2 superfamily, participating in homologous recombination repair. DNA damage is the central driver of aging, but there is no direct evidence of an association between RAD54B and vascular aging. The present study sought to investigate the role and mechanisms of RAD54B in endothelial senescence. In senescent animal models, including spontaneously hypertensive rats, normal aging mice, and D-gal-induced senescent mice, and senescent cell models induced by H2O2, D-gal, and culture, RAD54B was remarkably downregulated. Knockdown of RAD54B increased the expression of p53 and p21, increased the ratio of SA-β-gal-positive cells, and decreased the proportion of EdU-positive cells. Conversely, overexpression of RAD54B reversed the senescent phenotypes stimulated by H2O2 and delayed replicative endothelial senescence. Mechanistically, silencing RAD54B compensatorily increased the expression of RAD51/XRCC4, which remained unchanged in H2O2-induced senescence. RAD54B lacking the SNF2 domain could still reverse the increasing expression of p53/p21 induced by H2O2. RAD54B reduced γH2A.X expression and inhibited the expression and phosphorylation of CHK1. In conclusion, RAD54B exerts a direct protective effect against DNA damage through enhancing homologous recombination repair in endothelial senescence, resulting in inhibition of the downstream CHK1/p53/p21 pathway, suggesting that RAD54B may be a potential therapeutic target for vascular aging-associated diseases.

A Novel Role of Hyaluronic Acid and Proteoglycan Link Protein 1 (HAPLN1) in Delaying Vascular Endothelial Cell Senescence

Cardiovascular diseases (CVDs) are the most common cardiovascular system disorders. Cellular senescence is a key mechanism associated with dysfunction of aged vascular endothelium. Hyaluronic acid and proteoglycan link protein 1 (HAPLN1) has been known to non-covalently link hyaluronic acid (HA) and proteoglycans (PGs), and forms and stabilizes HAPLN1-containing aggregates as a major component of extracellular matrix. Our previous study showed that serum levels of HAPLN1 decrease with aging. Here, we found that the HAPLN1 gene expression was reduced in senescent human umbilical vein endothelial cells (HUVECs). Moreover, a recombinant human HAPLN1 (rhHAPLN1) decreased the activity of senescence-associated β-gal and inhibited the production of senescence-associated secretory phenotypes, including IL-1β, CCL2, and IL-6. rhHAPLN1 also down-regulated IL-17A levels, which is known to play a key role in vascular endothelial senescence. In addition, rhHAPLN1 protected senescent HUVECs from oxidative stress by reducing cellular reactive oxygen species levels, thus promoting the function and survival of HUVECs and leading to cellular proliferation, migration, and angiogenesis. We also found that rhHAPLN1 not only increases the sirtuin 1 (SIRT1) levels, but also reduces the cellular senescence markers levels, such as p53, p21, and p16. Taken together, our data indicate that rhHAPLN1 delays or inhibits the endothelial senescence induced by various aging factors, such as replicative, IL-17A, and oxidative stress-induced senescence, thus suggesting that rhHAPLN1 may be a promising therapeutic for CVD and atherosclerosis.

JMJD6 protects against isoproterenol-induced cardiac hypertrophy via inhibition of NF-κB activation by demethylating R149 of the p65 subunit

Histone modification plays an important role in pathological cardiac hypertrophy and heart failure. In this study we investigated the role of a histone arginine demethylase, Jumonji C domain-containing protein 6 (JMJD6) in pathological cardiac hypertrophy. Cardiac hypertrophy was induced in rats by subcutaneous injection of isoproterenol (ISO, 1.2 mg·kg-1·d-1) for a week. At the end of the experiment, the rats underwent echocardiography, followed by euthanasia and heart collection. We found that JMJD6 levels were compensatorily increased in ISO-induced hypertrophic cardiac tissues, but reduced in patients with heart failure with reduced ejection fraction (HFrEF). Furthermore, we demonstrated that JMJD6 overexpression significantly attenuated ISO-induced hypertrophy in neonatal rat cardiomyocytes (NRCMs) evidenced by the decreased cardiomyocyte surface area and hypertrophic genes expression. Cardiac-specific JMJD6 overexpression in rats protected the hearts against ISO-induced cardiac hypertrophy and fibrosis, and rescued cardiac function. Conversely, depletion of JMJD6 by single-guide RNA (sgRNA) exacerbated ISO-induced hypertrophic responses in NRCMs. We revealed that JMJD6 interacted with NF-κB p65 in cytoplasm and reduced nuclear levels of p65 under hypertrophic stimulation in vivo and in vitro. Mechanistically, JMJD6 bound to p65 and demethylated p65 at the R149 residue to inhibit the nuclear translocation of p65, thus inactivating NF-κB signaling and protecting against pathological cardiac hypertrophy. In addition, we found that JMJD6 demethylated histone H3R8, which might be a new histone substrate of JMJD6. These results suggest that JMJD6 may be a potential target for therapeutic interventions in cardiac hypertrophy and heart failure.

Eicosapentaenoic acid (EPA) reduces pulmonary endothelial dysfunction and inflammation due to changes in protein expression during exposure to particulate matter air pollution

AIMS

Inhalation of air pollution small particle matter (PM) is a leading cause of cardiovascular (CV) disease. Exposure to PMs causes endothelial cell (EC) dysfunction as evidenced by nitric oxide (NO) synthase uncoupling, vasoconstriction and inflammation. Eicosapentaenoic acid (EPA) has been shown to mitigate PM-induced adverse cardiac changes in patients receiving omega-3 fatty acid supplementation. We set out to determine the pro-inflammatory effects of multiple PMs (urban and fine) on pulmonary EC NO bioavailability and protein expression, and whether EPA restores EC function under these conditions.

METHODS AND RESULTS

We pretreated pulmonary ECs with EPA and then exposed them to urban or fine air pollution PMs. LC/MS-based proteomic analysis to assess relative expression levels. Expression of adhesion molecules was measured by immunochemistry. The ratio of NO to peroxynitrite (ONOO-) release, an indication of eNOS coupling, was measured using porphyrinic nanosensors following calcium stimulation. Urban/fine PMs also modulated 9/12 and 13/36 proteins, respectively, linked to platelet and neutrophil degranulation pathways and caused > 50% (p < 0.001) decrease in the stimulated NO/ONOO- release ratio. EPA treatment altered expression of proteins involved in these inflammatory pathways, including a decrease in peroxiredoxin-5 and an increase in superoxide dismutase-1. EPA also increased expression of heme oxygenase-1 (HMOX1), a cytoprotective protein, by 2.1-fold (p = 0.024). EPA reduced elevations in sICAM-1 levels by 22% (p < 0.01) and improved the NO/ONOO- release ratio by > 35% (p < 0.05).

CONCLUSION

These cellular changes may contribute to anti-inflammatory, cytoprotective and lipid changes associated with EPA treatment during air pollution exposure.

Echinacoside ameliorates 5-fluorouracil-induced endothelial injury and senescence through SIRT1 activation

Echinacoside (ECH) is a natural bioactive component with antioxidant, anti-inflammatory, anti-apoptosis, and anti-tumor properties. In the current study, we explore the ECH-mediated protective effect and underlying mechanism of 5-fluorouracil (5-FU)-induced endothelial injury and senescence in the Human umbilical vein endothelial cells (HUVECs). In HUVECs, Cell viability, Apoptosis and Senescence assays evaluated 5-fluorouracil-induced endothelial injury and senescence. Protein expressions were assessed using RT-qPCR and Western blotting. Our results showed that 5-FU-induced endothelial injury and endothelial cell senescence could be improved when treated with ECH in HUVECs. ECH treatment potentially attenuated oxidative stress and ROS production in HUVECs. In addition, the effect of ECH on autophagy markedly reduced the percentage of HUVECs with LC3-II dots and suppressed the Beclin-1 and ATG7 mRNA expression but enhanced the p62 mRNA expression. Besides, ECH treatment significantly increased migrated cells and suppressed the adhesion of THP-1 monocytes in HUVECs. Furthermore, ECH treatment activated the SIRT1 pathway, and its related proteins (SIRT1, p-AMPK and eNOS) expression increased. Nicotinamide (NAM), an inhibitor of SIRT1, significantly attenuated the ECH-induced decrease in the apoptotic rate, increased SA-β-gal-positive cells and significantly reversed the ECH-induced reduction of endothelial senescence. Our results demonstrated that ECH employed endothelial injury and senescence in HUVECs via activation of the SIRT1 pathway.

Human hair proteins as natural reactive oxygen species scavengers for in vitro applications

Human hair proteins are recognized for their intrinsically high cysteine content. They can be solubilized while preserving their highly reductive thiol groups for free radical scavenging applications. The presence of aromatic and nucleophilic amino acids such as methionine, serine, phenylalanine, and threonine further contribute to the antioxidative potential of this material. Herein, utilizing the DPPH (2,2-diphenyl-1-picrylhydrazyl) and acellular 2',7'-dichlorodihydrofluorescein diacetate (H₂ DCFDA) assays, keratins are demonstrated to possess the highest radical scavenging activity among the studied hair proteins. Consequently, protection against hydrogen peroxide-induced oxidative stress in human dermal fibroblasts (HDFs) cultured in human hair keratin supplemented media is demonstrated. Quenching of reactive oxygen species in the HDF is observed using the CellROX Green dye and the expression levels of antioxidant (HMOX1, SOD2, GPX1) and tumor suppressor (TP53) genes is analyzed using qPCR. Collectively, this study presents further evidence and demonstrates the in vitro application potential of hair proteins, especially keratins, as an antioxidizing supplement.

Impaired iron recycling from erythrocytes is an early hallmark of aging

Aging affects iron homeostasis, as evidenced by tissue iron loading and anemia in the elderly. Iron needs in mammals are met primarily by iron recycling from senescent red blood cells (RBCs), a task chiefly accomplished by splenic red pulp macrophages (RPMs) via erythrophagocytosis. Given that RPMs continuously process iron, their cellular functions might be susceptible to age-dependent decline, a possibility that has been unexplored to date. Here, we found that 10- to 11-month-old female mice exhibit iron loading in RPMs, largely attributable to a drop in iron exporter ferroportin, which diminishes their erythrophagocytosis capacity and lysosomal activity. Furthermore, we identified a loss of RPMs during aging, underlain by the combination of proteotoxic stress and iron-dependent cell death resembling ferroptosis. These impairments lead to the retention of senescent hemolytic RBCs in the spleen, and the formation of undegradable iron- and heme-rich extracellular protein aggregates, likely derived from ferroptotic RPMs. We further found that feeding mice an iron-reduced diet alleviates iron accumulation in RPMs, enhances their ability to clear erythrocytes, and reduces damage. Consequently, this diet ameliorates hemolysis of splenic RBCs and reduces the burden of protein aggregates, mildly increasing serum iron availability in aging mice. Taken together, we identified RPM collapse as an early hallmark of aging and demonstrated that dietary iron reduction improves iron turnover efficacy.

MLN-4760 Induces Oxidative Stress without Blood Pressure and Behavioural Alterations in SHRs: Roles of Nfe2l2 Gene, Nitric Oxide and Hydrogen Sulfide

Reduced angiotensin 1-7 bioavailability due to inhibition of angiotensin-converting enzyme 2 (ACE2) may contribute to increased mortality in hypertensive individuals during COVID-19. However, effects of ACE2 inhibitor MLN-4760 in brain functions remain unknown. We investigated the selected behavioural and hemodynamic parameters in spontaneously hypertensive rats (SHRs) after a 2-week s.c. infusion of MLN-4760 (dose 1 mg/kg/day). The biochemical and molecular effects of MLN-4760 were investigated in the brainstem and blood plasma. MLN-4760 had no effects on hemodynamic and behavioural parameters. However, MLN-4760 increased plasma hydrogen sulfide (H₂S) level and total nitric oxide (NO) synthase activity and conjugated dienes in the brainstem. Increased NO synthase activity correlated positively with gene expression of Nos3 while plasma H₂S levels correlated positively with gene expressions of H₂S-producing enzymes Mpst, Cth and Cbs. MLN-4760 administration increased gene expression of Ace2, Sod1, Sod2, Gpx4 and Hmox1, which positively correlated with expression of Nfe2l2 gene encoding the redox-sensitive transcription factor NRF2. Collectively, MLN-4760 did not exacerbate pre-existing hypertension and behavioural hyperactivity/anxiety in SHRs. However, MLN-4760-induced oxidative damage in brainstem was associated with activation of NO- and H₂S-mediated compensatory mechanisms and with increased gene expression of antioxidant, NO- and H₂S-producing enzymes that all correlated positively with elevated Nfe2l2 expression.

Comparison of the Antihypertensive Activity of Phenolic Acids

Phenolic acids, found in cereals, legumes, vegetables, and fruits, have various biological functions. We aimed to compare the antihypertensive potential of different phenolic acids by evaluating their ACE inhibitory activity and cytoprotective capacity in EA.hy 926 endothelial cells. In addition, we explored the mechanism underlying the antihypertensive activity of sinapic acid. Of all the phenolic acids studied, sinapic acid, caffeic acid, coumaric acid, and ferulic acid significantly inhibited ACE activity. Moreover, gallic acid, sinapic acid, and ferulic acid significantly enhanced intracellular NO production. Based on the results of GSH depletion, ROS production, and MDA level analyses, sinapic acid was selected to study the mechanism underlying the antihypertensive effect. Sinapic acid decreases endothelial dysfunction by enhancing the expression of antioxidant-related proteins. Sinapic acid increased phosphorylation of eNOS and Akt in a dose-dependent manner. These findings indicate the potential of sinapic acid as a treatment for hypertension.

Hesperidin Preferentially Stimulates Transient Receptor Potential Vanilloid 1, Leading to NO Production and Mas Receptor Expression in Human Umbilical Vein Endothelial Cells

Here, the mechanism of vasorelaxant Mas receptor (MasR) expression elevated by hesperidin in spontaneously hypertensive rats was investigated in human umbilical vein endothelial cells (HUVECs). HUVECs were cultured with 1 μM hesperidin for 2 h, following the measurements of nitric oxide (NO) production and vasomotor-related receptors' expression. Hesperidin significantly promoted NO production (224.1 ± 18.3%, P < 0.01 vs control) in the HUVECs. Only the MasR expression was upregulated (141.2 ± 12.5%, P < 0.05 vs control), whereas a MasR antagonist did not alter the hesperidin-induced NO production. When a transient receptor potential vanilloid 1 (TRPV1) was knocked down by silencing RNA or Ca²⁺/calmodulin-dependent kinase II (CaMKII) and p38 mitogen-activated protein kinase (p38 MAPK) were inhibited, the increased MasR expression by hesperidin was abrogated. The inhibitions of CaMKII and endothelial NO synthase (eNOS) abolished the hesperidin-induced NO production. The structure-activity relationship analysis of flavonoids demonstrated that the B ring of the twisted flavonoid skeleton with a hydroxy group at the 3' position was a crucial factor for TRPV1 stimulation. Taken together, it was demonstrated that hesperidin may stimulate TRPV1-mediated cascades, leading to the activation of two signaling axes, CaMKII/p38 MAPK/MasR expression and CaMKII/eNOS/NO production in HUVECs.

Therapeutic potential of traditional Chinese medicine in atherosclerosis: A review

Atherosclerosis is the onset of endothelial cell damage and is characterized by abnormal accumulation of fibrinogen and lipid in large and middle arteries. Recent researches indicate that traditional Chinese medicine including Notoginseng Radix et Rhizoma, Astragali Radix, Salviae Miltiorrhizae Radix et Rhizoma, Ginseng Radix et Rhizoma, Fructus Crataegi, Glycyrrhizae Radix et Rhizoma, Polygoni Multiflori Radix, Fructus Lycii, and Coptidis Rhizoma have therapeutic effects on atherosclerosis. Furthermore, the pharmacological roles of these kinds of traditional Chinese medicine in atherosclerosis refer to endothelial function influences, cell proliferation and migration, platelet aggregation, thrombus formation, oxidative stress, inflammation, angiogenesis, apoptosis, autophagy, lipid metabolism, and the gut microbiome. Traditional Chinese medicine may serve as potential and effective anti-atherosclerosis drugs. However, a critical study has shown that Notoginseng Radix et Rhizoma may also have toxic effects including pustules, fever, and elevate circulating neutrophil count. Further high-quality studies are still required to determine the clinical safety and efficacy of traditional Chinese medicine and its active ingredients.

Disturbance of Fatty Acid Metabolism Promoted Vascular Endothelial Cell Senescence via Acetyl-CoA-Induced Protein Acetylation Modification

Endothelial cell senescence is the main risk factor contributing to vascular dysfunction and the progression of aging-related cardiovascular diseases. However, the relationship between endothelial cell metabolism and endothelial senescence remains unclear. The present study provides novel insight into fatty acid metabolism in the regulation of endothelial senescence. In the replicative senescence model and H₂O₂-induced premature senescence model of primary cultured human umbilical vein endothelial cells (HUVECs), fatty acid oxidation (FAO) was suppressed and fatty acid profile was disturbed, accompanied by downregulation of proteins associated with fatty acid uptake and mitochondrial entry, in particular the FAO rate-limiting enzyme carnitine palmitoyl transferase 1A (CPT1A). Impairment of fatty acid metabolism by silencing CPT1A or CPT1A inhibitor etomoxir facilitated the development of endothelial senescence, as implied by the increase of p53, p21, and senescence-associated β-galactosidase, as well as the decrease of EdU-positive proliferating cells. In the contrary, rescue of FAO by overexpression of CPT1A or supplement of short chain fatty acids (SCFAs) acetate and propionate ameliorated endothelial senescence. In vivo, treatment of acetate for 4 weeks lowered the blood pressure and alleviated the senescence-related phenotypes in aortas of Ang II-infused mice. Mechanistically, fatty acid metabolism regulates endothelial senescence via acetyl-coenzyme A (acetyl-CoA), as implied by the observations that suppression of acetyl-CoA production using the inhibitor of ATP citrate lyase NDI-091143 accelerated senescence of HUVECs and that supplementation of acetyl-CoA prevented H₂O₂-induced endothelial senescence. Deficiency of acetyl-CoA resulted in alteration of acetylated protein profiles which are associated with cell metabolism and cell cycle. These findings thus suggest that improvement of fatty acid metabolism might ameliorate endothelial senescence-associated cardiovascular diseases.

A biological rationale for the disparate effects of omega-3 fatty acids on cardiovascular disease outcomes

The omega-3 fatty acids (n3-FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) rapidly incorporate into cell membranes where they modulate signal transduction pathways, lipid raft formation, and cholesterol distribution. Membrane n3-FAs also form specialized pro-resolving mediators and other intracellular oxylipins that modulate inflammatory pathways, including T-cell differentiation and gene expression. Cardiovascular (CV) trials have shown that EPA, administered as icosapent ethyl (IPE), reduces composite CV events, along with plaque volume, in statin-treated, high-risk patients. Mixed EPA/DHA regimens have not shown these benefits, perhaps as the result of differences in formulation, dosage, or potential counter-regulatory actions of DHA. Indeed, EPA and DHA have distinct, tissue-specific effects on membrane structural organization and cell function. This review summarizes: (1) results of clinical outcome and imaging trials using n3-FA formulations; (2) membrane interactions of n3-FAs; (3) effects of n3-FAs on membrane oxidative stress and cholesterol crystalline domain formation during hyperglycemia; (4) n3-FA effects on endothelial function; (5) role of n3-FA-generated metabolites in inflammation; and (6) ongoing and future clinical investigations exploring treatment targets for n3-FAs, including COVID-19.

Post-exposure persistence of nitric oxide upregulation in skin cells irradiated by UV-A

Evidence suggests that exposure to UV-A radiation can liberate nitric oxide from skin cells eliciting vasodilation in-vivo. However, the duration of nitric oxide release in skin cells after UV exposure is not well studied, with emphasis on UV-B mediated iNOS upregulation. The current study demonstrated persistence of nitric oxide release in a dark reaction after moderate UV-A exposure, peaking around 48 h post exposure; this effect was shown in keratinocytes, fibroblasts and endothelial cells from neonatal donors and keratinocytes from aged donors and confirmed the hypothesis that UV-A exposure appeared to upregulate cNOS alongside iNOS. Release of nitric oxide in the skin cells induced by a moderate exposure to UV-A in sunlight may be especially beneficial for some demographic groups such as the elderly, hypertensive patients or those with impaired nitric oxide function, not only during exposure but many hours and days after that.

Angiotensin-(1-7), a protective peptide against vascular aging

Vascular aging is a complex and multifaceted process that provokes profound molecular, structural, and functional changes in the vasculature. Eventually, these profound aging alterations make arteries more prone to vascular disease, including hypertension, atherosclerosis and other arterial complications that impact the organism beyond the cardiovascular system and accelerate frailty. For these reasons, preventing or delaying the hallmarks of vascular aging is nowadays a major health goal, especially in our aged societies. In this context, angiotensin(Ang)-(1-7), a major player of the protective branch of the renin-angiotensin system, has gained relevance over recent years as growing knowledge on its anti-aging properties is being unveiled. Here, we briefly review the main actions of Ang-(1-7) against vascular aging. These include protection against vascular cell senescence, anti-inflammatory and antioxidant effects together with the induction of cytoprotective systems. Ang-(1-7) further ameliorates endothelial dysfunction, a hallmark of vascular aging and disease, attenuates fibrosis and calcification and promotes protective angiogenesis and repair. Although further research is needed to better understand the anti-aging properties of Ang-(1-7) on the vasculature, this heptapeptide arises as a promising pharmacological tool for preventing vascular aging and frailty.

Tissue-Protective Mechanisms of Bioactive Phytochemicals in Flap Surgery

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

Role of thioredoxin-interacting protein in mediating endothelial dysfunction in hypertension

Excessive oxidative stress is a major causative factor of endothelial dysfunction in hypertension. As an endogenous pro-oxidant, thioredoxin-interacting protein (TXNIP) contributes to oxidative damage in various tissues. The present study aimed to investigate the role of TXNIP in mediating endothelial dysfunction in hypertension. In vivo, an experimental model of acquired hypertension was established with two-kidney, one-clip (2K1C) surgery. The expression of TXNIP in the vascular endothelial cells of multiple vessels was significantly increased in hypertensive rats compared with sham-operated rats. Resveratrol, a TXNIP inhibitor, suppressed vascular oxidative damage and increased the expression and activity of eNOS in the aorta of hypertensive rats. Notably, impaired endothelium-dependent vasodilation was effectively improved by TXNIP inhibition in hypertensive rats. In vitro, we observed that Ang II increased the expression of TXNIP in primary human aortic endothelial cells (HAECs) and that TXNIP knockdown by RNA interference alleviated cellular oxidative stress damage and mitigated the impaired eNOS activation and intracellular nitric oxide (NO) production observed in Ang II-treated HAECs. However, inhibiting thioredoxin (TRX) with PX-12 completely blunted the protective effect of silencing TXNIP. In addition, TXNIP knockdown facilitated TRX expression and promoted TRX nuclear translocation to further activate AP1 and REF1. TRX overexpression exhibited favorable effects on eNOS/NO homeostasis in Ang II-treated HAECs. Thus, TXNIP contributes to oxidative stress and endothelial dysfunction in hypertension, and these effects are dependent on the antioxidant capacity of TRX, suggesting that targeting TXNIP may be a novel strategy for antihypertensive therapy.

Hemin-induced increase in saponin content contributes to the alleviation of osmotic and cold stress damage to Conyza blinii in a heme oxygenase 1-dependent manner

Hemin can improve the stress resistance of plants through the heme oxygenase system. Additionally, substances contained in plants, such as secondary metabolites, can improve stress resistance. However, few studies have explored the effects of hemin on secondary metabolite content. Therefore, the effects of hemin on saponin synthesis and the mechanism of plant injury relief by hemin in Conyza blinii were investigated in this study. Hemin treatment promoted plant growth and increased the antioxidant enzyme activity and saponin content of C. blinii under osmotic stress and cold stress. Further study showed that hemin could provide sufficient precursors for saponin synthesis by improving the photosynthetic capacity of C. blinii and increasing the gene expression of key enzymes in the saponin synthesis pathway, thus increasing the saponin content. Moreover, the promotion effect of hemin on saponin synthesis is dependent on heme oxygenase-1 and can be reversed by the inhibitor Zn-protoporphyrin-IX (ZnPPIX). This study revealed that hemin can increase the saponin content of C. blinii and alleviate the damage caused by abiotic stress, and it also broadened the understanding of the relationship between hemin and secondary metabolites in plant abiotic stress relief.

HO-1 nuclear accumulation and interaction with NPM1 protect against stress-induced endothelial senescence independent of its enzymatic activity

Heme oxygenase-1 (HO-1) has attracted accumulating attention for its antioxidant enzymatic activity. However, the exact regulatory role of its non-enzymatic activity in the cardiovascular system remains unaddressed. Here, we show that HO-1 was accumulated in the nuclei of stress-induced senescent endothelial cells, and conferred protection against endothelial senescence independent of its enzymatic activity. Overexpression of ΔHO-1, a truncated HO-1 without transmembrane segment (TMS), inhibited H2O2-induced endothelial senescence. Overexpression of ΔHO-1H25A, the catalytically inactive form of ΔHO-1, also exhibited anti-senescent effect. In addition, infection of recombinant adenovirus encoding ΔHO-1 with three nuclear localization sequences (NLS), alleviated endothelial senescence induced by knockdown of endogenous HO-1 by CRISPR/Cas9. Moreover, repression of HO-1 nuclear translocation by silencing of signal peptide peptidase (SPP), which is responsible for enzymatic cleavage of the TMS of HO-1, exacerbated endothelial senescence. Mechanistically, nuclear HO-1 interacted with NPM1 N-terminal portion, prevented NPM1 translocation from nucleolus to nucleoplasm, thus disrupted NPM1/p53/MDM2 interactions and inhibited p53 activation by NPM1, finally resisted endothelial senescence. This study provides a novel understanding of HO-1 as a promising therapeutic strategy for vascular senescence-related cardiovascular diseases.

Endothelial Dysfunction in Atherosclerotic Cardiovascular Diseases and Beyond: From Mechanism to Pharmacotherapies

The endothelium, a cellular monolayer lining the blood vessel wall, plays a critical role in maintaining multiorgan health and homeostasis. Endothelial functions in health include dynamic maintenance of vascular tone, angiogenesis, hemostasis, and the provision of an antioxidant, anti-inflammatory, and antithrombotic interface. Dysfunction of the vascular endothelium presents with impaired endothelium-dependent vasodilation, heightened oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, and endothelial cell senescence. Recent studies have implicated altered endothelial cell metabolism and endothelial-to-mesenchymal transition as new features of endothelial dysfunction. Endothelial dysfunction is regarded as a hallmark of many diverse human panvascular diseases, including atherosclerosis, hypertension, and diabetes. Endothelial dysfunction has also been implicated in severe coronavirus disease 2019. Many clinically used pharmacotherapies, ranging from traditional lipid-lowering drugs, antihypertensive drugs, and antidiabetic drugs to proprotein convertase subtilisin/kexin type 9 inhibitors and interleukin 1β monoclonal antibodies, counter endothelial dysfunction as part of their clinical benefits. The regulation of endothelial dysfunction by noncoding RNAs has provided novel insights into these newly described regulators of endothelial dysfunction, thus yielding potential new therapeutic approaches. Altogether, a better understanding of the versatile (dys)functions of endothelial cells will not only deepen our comprehension of human diseases but also accelerate effective therapeutic drug discovery. In this review, we provide a timely overview of the multiple layers of endothelial function, describe the consequences and mechanisms of endothelial dysfunction, and identify pathways to effective targeted therapies. SIGNIFICANCE STATEMENT: The endothelium was initially considered to be a semipermeable biomechanical barrier and gatekeeper of vascular health. In recent decades, a deepened understanding of the biological functions of the endothelium has led to its recognition as a ubiquitous tissue regulating vascular tone, cell behavior, innate immunity, cell-cell interactions, and cell metabolism in the vessel wall. Endothelial dysfunction is the hallmark of cardiovascular, metabolic, and emerging infectious diseases. Pharmacotherapies targeting endothelial dysfunction have potential for treatment of cardiovascular and many other diseases.

Sorting nexin 3 induces heart failure via promoting retromer-dependent nuclear trafficking of STAT3

Sorting nexins (SNXs), the retromer-associated cargo binding proteins, have emerged as critical regulators of the trafficking of proteins involved in the pathogenesis of diverse diseases. However, studies of SNXs in the development of cardiovascular diseases, especially cardiac hypertrophy and heart failure, are lacking. Here, we ask whether SNX3, the simplest structured isoform in the SNXs family, may act as a key inducer of myocardial injury. An increased level of SNX3 was observed in failing hearts from human patients and mice. Cardiac-specific Snx3 knockout (Snx3-cKO) mice and Snx3 transgenic (Snx3-cTg) mice were generated to evaluate the role of Snx3 in myocardial hypertrophy, fibrosis, and heart function by morphology, echocardiography, histological staining, and hypertrophic biomarkers. We report that Snx3-cKO in mice significantly protected against isoproterenol (ISO)-induced cardiac hypertrophy at 12 weeks. Conversely, Snx3-cTg mice were more susceptible to ISO-induced cardiac hypertrophy at 12 weeks and showed aggravated cardiac injury even heart failure at 24 weeks. Immunoprecipitation-based mass spectrometry, immunofluorescent staining, co-immunoprecipitation, localized surface plasmon resonance, and proximity ligation assay were performed to examine the direct interaction of SNX3-retromer with signal transducer and activator of transcription 3 (STAT3). We discovered that STAT3 was a new interacting partner of SNX3-retromer, and SNX3-retromer served as an essential platform for assembling gp130/JAK2/STAT3 complexes and subsequent phosphorylation of STAT3 by direct combination at EE. SNX3-retromer and STAT3 complexes were transiently imported into the nucleus after hypertrophic stimuli. The pharmacological inhibition or knockdown of STAT3 reversed SNX3 overexpression-induced myocardial injury. STAT3 overexpression blunts the beneficial function of SNX3 knockdown on hypertrophic cardiomyocytes. We show that SNX3-retromer promoted importin α3-mediated STAT3 nuclear trafficking and ultimately leading to cardiac injury. Taken together, our study reveals that SNX3 plays a key role in cardiac function and implicates SNX3 as a potential therapeutic target for cardiac hypertrophy and heart failure.

How Periodontal Disease and Presence of Nitric Oxide Reducing Oral Bacteria Can Affect Blood Pressure

Nitric oxide (NO), a small gaseous and multifunctional signaling molecule, is involved in the maintenance of metabolic and cardiovascular homeostasis. It is endogenously produced in the vascular endothelium by specific enzymes known as NO synthases (NOSs). Subsequently, NO is readily oxidized to nitrite and nitrate. Nitrite is also derived from exogenous inorganic nitrate (NO₃) contained in meat, vegetables, and drinking water, resulting in greater plasma NO₂ concentration and major reduction in systemic blood pressure (BP). The recycling process of nitrate and nitrite to NO (nitrate-nitrite-NO pathway), known as the enterosalivary cycle of nitrate, is dependent upon oral commensal nitrate-reducing bacteria of the dorsal tongue. Veillonella, Actinomyces, Haemophilus, and Neisseria are the most copious among the nitrate-reducing bacteria. The use of chlorhexidine mouthwashes and tongue cleaning can mitigate the bacterial nitrate-related BP lowering effects. Imbalances in the oral reducing microbiota have been associated with a decrease of NO, promoting endothelial dysfunction, and increased cardiovascular risk. Although there is a relationship between periodontitis and hypertension (HT), the correlation between nitrate-reducing bacteria and HT has been poorly studied. Restoring the oral flora and NO activity by probiotics may be considered a potential therapeutic strategy to treat HT.

Korean Red ginseng prevents endothelial senescence by downregulating the HO-1/NF-κB/miRNA-155-5p/eNOS pathway

Background

Korean Red ginseng extract (KRGE) has beneficial effects on the cardiovascular system by improving endothelial cell function. However, its pharmacological effect on endothelial cell senescence has not been clearly elucidated. Therefore, we examined the effect and molecular mechanism of KRGE on the senescence of human umbilical vein endothelial cells (HUVECs).

Methods

HUVECs were grown in normal or KRGE-supplemented medium. Furthermore, they were transfected with heme oxygenase-1 (HO-1) gene or treated with its inhibitor, a NF-κB inhibitor, and a miR-155-5p mimic or inhibitor. Senescence-associated characteristics of endothelial cells were determined by biochemical and immunohistochemical analyses.

Results

Treatment of HUVECs with KRGE resulted in delayed onset and progression of senescence-associated characteristics, such as increased lysosomal acidic β-galactosidase and decreased telomerase activity, angiogenic dysfunction, and abnormal cell morphology. KRGE preserved the levels of anti-senescent factors, such as eNOS-derived NO, MnSOD, and cyclins D and A: however, it decreased the levels of senescence-promoting factors, such as ROS, activated NF-κB, endothelial cell inflammation, and p21 expression. The beneficial effects of KRGE were due to the induction of HO-1 and the inhibition of NF-κB-dependent biogenesis of miR-155-5p that led to the downregulation of eNOS. Moreover, treatment with inhibitors of HO-1, NF-κB, and miR-155-5p abolished the anti-senescence effects of KRGE.

Conclusion

KRGE delayed or prevented HUVEC senescence through a signaling cascade involving the induction of HO-1, the inhibition of NF-κB-dependent miR-155-5p biogenesis, and the maintenance of the eNOS/NO axis activity, suggesting that it may protect against vascular diseases associated with endothelial senescence.

BRG1 Activates PR65A Transcription to Regulate NO Bioavailability in Vascular Endothelial Cells

Vascular endothelial cells contribute to the pathogenesis of cardiovascular diseases by producing and disseminating angiocrine factors. Nitric oxide (NO), catalyzed by endothelial NO synthase (eNOS), is one of the prototypical angiocrine factors. eNOS activity is modulated by site-specific phosphorylation. We have previously shown that endothelial-specific knockdown of BRG1 in Apoe^–/– mice attenuates the development of atherosclerosis, in which eNOS-dependent NO catalysis plays an antagonizing role. Here we report that attenuation of atherogenesis in mice by BRG1 knockdown was accompanied by partial restoration of NO biosynthesis by 44% in the arteries and a simultaneous up-regulation of eNOS serine 1177 phosphorylation by 59%. Indeed, BRG1 depletion or inhibition ameliorated oxLDL-induced loss of NO bioavailability and eNOS phosphorylation in cultured endothelial cells. Further analysis revealed that BRG1 regulated eNOS phosphorylation and NO synthesis by activating the transcription of protein phosphatase 2A (PP2A) structural subunit a (encoded by PR65A). BRG1 interacted with ETS1, was recruited by ETS1 to the PR65A promoter, and cooperated with ETS1 to activate PR65A transcription. Finally, depletion of ETS1, similar to BRG1, repressed PR65A induction, normalized eNOS phosphorylation, and rescued NO biosynthesis in endothelial cells treated with oxLDL. In conclusion, our data characterize a novel transcriptional cascade that regulates NO bioavailability in vascular endothelial cells.

Eukaryotic elongation factor 2 kinase inhibitor, A484954 lowered blood pressure in spontaneously hypertensive rats via inducing vasorelaxation

Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) suppresses protein translation. We previously reported eEF2K expression was upregulated in mesenteric arteries (MA) from spontaneously hypertensive rats (SHR). We have recently revealed A484954, an eEF2K inhibitor, acutely suppressed vasopressor agonists-induced increase of blood pressure (BP) in normal Wistar rats. In this study, we examined the acute effects of A484954 on BP in SHR and explored underlying mechanisms. BP was measured by a carotid cannulation method in SHR. Isometric contraction in MA from SHR was measured. Endothelial nitric oxide synthase (eNOS) dimerization was measured by low-temperature sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. A484954 lowered BP in 15-week-old SHR. A484954 induced relaxation in MA from both 4- and 7-9-week-old SHR. In MA from 4-week-old SHR, A484954-induced relaxation was inhibited almost completely by a NOS inhibitor, N^G-nitro-l-arginine methyl ester (l-NAME) and significantly by a β blocker, propranolol. In MA from 7-9-week-old SHR, on the other hand, A484954-induced relaxation was inhibited partly either by l-NAME, indomethacin, a cyclooxygenase inhibitor, or l-NAME + indomethacin. A484954 promoted the dimerization of eNOS in human endothelial cells. In summary, we have revealed A484954 lowers BP in SHR perhaps through the vasorelaxation via the production of endothelium-derived relaxing factors.

Association of Omnivorous and Vegetarian Diets With Antioxidant Defense Mechanisms in Men

Background Evidence that a vegetarian diet rich in antioxidants contributes to cardiovascular health are growing, however, the underlying molecular mechanisms remain unknown. HO-1 (heme-oxygenase-1), a marker of adaptive response, is protective against oxidative stress and has shown cardioprotective effects. Therefore, we evaluated circulating HO-1 levels and the effect of plasma from omnivorous and vegetarians in endothelial cells (human umbilical vein endothelial cells) on modulating NRF2 (nuclear factor erythroid 2-like 2)/HO-1 and nitric oxide production. Methods and Results From 745 participants initially recruited, 44 omnivorous and 44 vegetarian men matched by age and absence of cardiovascular risk factors and diseases were included in this study. Circulating HO-1 was measured using ELISA and human umbilical vein endothelial cells were incubated with plasma from omnivorous and vegetarians. Higher circulating HO-1 concentrations were found in omnivorous compared with vegetarians. Plasma from omnivorous and not from vegetarians induced NRF2/HO-1 and nitric oxide production in human umbilical vein endothelial cells, and increased reactive oxygen species production and caspase activity after incubation with stressor stimulus. Conclusions We suggest that HO-1 induction in omnivorous may indicate a pro-oxidative status since HO-1 is activated under oxidative stress a state not seen in vegetarians.

Ginsenoside Rb1 reduces H2O2‑induced HUVEC dysfunction by stimulating the sirtuin‑1/AMP‑activated protein kinase pathway

Endothelial dysfunction and senescence are closely associated with cardiovascular diseases including atherosclerosis and hypertension. Ginsenoside Rb1 (Rb1), the major active constituent of ginseng, has been investigated intensively because of its anti-obesity and anti-inflammatory effects. In a previous study, hydrogen peroxide (H₂O₂) was applied to induce human umbilical vein endothelial cell (HUVEC) aging. It was demonstrated that Sirtuin-1 (SIRT1) was activated by Rb1 to protect HUVECs from H₂O₂-induced senescence. However, the mechanisms are not fully understood. The present study examined the role of AMP-activated protein kinase (AMPK), an energy sensor of cellular metabolism, in the signaling pathway of SIRT1 during H₂O₂-stimulated HUVEC aging. It was identified that Rb1 restored the H₂O₂-induced reduction of SIRT1 expression, which was consistent with our previous study, together with the activation of AMPK phosphorylation. Using compound C, an AMPK inhibitor, the role of AMPK in the protective effect of Rb1 against H₂O₂-induced HUVEC senescence was examined. It was identified that the induction of phosphorylated AMPK by Rb1 markedly increased endothelial nitric oxide synthase expression and nitric oxide production, and suppressed PAI-1 expression, which were abrogated in HUVECs pretreated with compound C. Further experiments demonstrated that nicotinamide, a SIRT1 inhibitor, downregulated the phosphorylation of AMPK and reduced the protective effects of Rb1 against H₂O₂-induced endothelial aging. Taken together, these results provide new insights into the possible molecular mechanisms by which Rb1 protects against H₂O₂-induced HUVEC senescence via the SIRT1/AMPK pathway.

The roles of MTOR and miRNAs in endothelial cell senescence

Accumulation of senescent cells in vascular endothelium is known to contribute to vascular aging and increases the risk of developing cardiovascular diseases. The involvement of classical pathways such as p53/p21 and p16/pRB in cellular senescence are well described but there are emerging evidence supporting the increasingly important role of mammalian target of rapamycin (MTOR) as driver of cellular senescence via these pathways or other effector molecules. MicroRNAs (miRNAs) are a highly conserved group of small non-coding RNAs (18-25 nucleotides), instrumental in modulating the expression of target genes associated with various biological and cellular processes including cellular senescence. The inhibition of MTOR activity is predominantly linked to cellular senescence blunting and prolonged lifespan in model organisms. To date, known miRNAs regulating MTOR in endothelial cell senescence remain limited. Herein, this review discusses the roles of MTOR and MTOR-associated miRNAs in regulating endothelial cell senescence, including the crosstalk between MTOR Complex 1 (MTORC1) and cell cycle pathways and the emerging role of MTORC2 in cellular senescence. New insights on how MTOR and miRNAs coordinate underlying molecular mechanisms of endothelial senescence will provide deeper understanding and clarity to the complexity of the regulation of cellular senescence.

HO-1 overexpression alleviates senescence by inducing autophagy via the mitochondrial route in human nucleus pulposus cells

Intervertebral disc degeneration (IDD) is closely associated with aging. Our previous studies have confirmed that heme oxygenase-1 (HO-1) can inhibit nucleus pulposus (NP) cell apoptosis. However, whether or not HO-1 is involved in NP cell senescence and autophagy is unclear. Our results indicated that HO-1 expression was reduced in IDD tissues and replicative senescent NP cells. HO-1 overexpression using a lentiviral vector reduced the NP cell senescence level, protected mitochondrial function, and promoted NP cell autophagy through the mitochondrial pathway. Autophagy inhibitor 3-MA pretreatment reversed the anti-senescent and protective effects on the mitochondrial function of HO-1, which promoted the degradation of the extracellular matrix (ECM) in the intervertebral disc. In vivo, HO-1 overexpression inhibited IDD and enhanced autophagy. In summary, these results suggested that HO-1 overexpression alleviates NP cell senescence by inducing autophagy via the mitochondrial route.

Heme oxygenase-1 contributes to the protective effect of resveratrol against endothelial dysfunction in STZ-induced diabetes in rats

Endothelial dysfunction is a common complication of diabetes that mainly stems from increased reactive oxygen species, which makes antioxidants of great benefit. Resveratrol (RSV) is an antioxidant that shows protective effects in a variety of disease models where the ameliorative effect appears to be mediated, in part, via heme oxygenase-1 (HO-1) induction. However, the pathophysiological relevance of HO-1 in the ameliorative response of RSV in endothelial dysfunction is not clearly defined. The present study was conducted to investigate whether HO-1 plays a role in diabetes-induced vascular dysfunction. Streptozotocin-diabetic rats were treated with RSV (10 mg/kg) in presence or absence of an HO-1 blocker, Zinc protoporphyrin (ZnPP) to assess vascular function and indicators of disease status. We found that RSV treatment significantly abrogated diabetes induced vascular dysfunction. This improvement was associated with the ability of RSV to decrease oxidative stress markers alongside a reduction in the aortic TGF-β expression, elevation of NOS3 expression and aortic nitrite concentration as well as HO activity. These ameliorative effects were diminished when ZnPP was administered prior to RSV. Our results clearly demonstrate the protective effects of RSV in diabetes-associated endothelial dysfunction and verified a causal role of HO-1 in this setting.

CO ameliorates endothelial senescence induced by 5-fluorouracil through SIRT1 activation

Endothelial senescence is the main risk factor that contributes to vascular dysfunction and the progression of vascular disease. Carbon monoxide (CO) plays an important role in preventing vascular dysfunction and in maintaining vascular physiology or homeostasis. The application of exogenous CO has been shown to confer protection in several models of cardiovascular injury or disease, including hypertension, atherosclerosis, balloon-catheter injury, and graft rejection. However, the mechanism by which CO prevents endothelial senescence has been largely unexplored. The aim of this study was to evaluate the effects of CO on endothelial senescence and to investigate the possible mechanisms underlying this process. We measured the levels of senescence-associated-β-galactosidase activity, senescence-associated secretory phenotype, reactive oxygen species (ROS) production, and stress granule in human umbilical vein endothelial cells and the WI-38 human diploid fibroblast cell line. We found that 5-fluorouracil (5FU)-induced ROS generation was inhibited by CO-releasing molecules (CORM)-A1 treatment, and endothelial senescence induced by 5FU was attenuated by CORM-A1 treatment. The SIRT1 inhibitor EX527 reversed the inhibitory effect of CO on the 5FU-induced endothelial senescence. Furthermore, SIRT1 deficiency abolished the stress granule formation by CO. Our results suggest that CO alleviates the endothelial senescence induced by 5FU through SIRT1 activation and may hence have therapeutic potential for the treatment of vascular diseases.

Human embryonic stem cell-derived exosomes promote pressure ulcer healing in aged mice by rejuvenating senescent endothelial cells

Background

Angiogenesis, as an endogenous repair mechanism, plays crucial roles in wound healing and tissue regeneration. However, this process is impaired in the elderly due to aging-related vascular endothelial dysfunction. This study was aimed to explore the pro-angiogenic effects of exosomes from human embryonic stem cells (ESC-Exos) in aged mice of pressure-induced ulcer model and the underlying mechanism.

Methods

Pressure ulcer wounds were created on the back of d-galactose-induced aging mice. ESC-Exos were locally applied onto the wound beds, with PBS as control. The effects of ESC-Exos on wound healing were analyzed by measuring wound closure rates, histological and immunofluorescence analyses. Then, the anti-aging effect of ESC-Exos on vascular endothelial cells was tested in an in vitro d-galactose-induced HUVEC senescence model.

Results

ESC-Exos could accelerate wound closure and enhance angiogenesis, and the senescence of vascular endothelial cells was significantly ameliorated after ESC-Exos treatment. In vitro, ESC-Exos could rejuvenate the senescence of endothelial cells and recover compromised proliferation, migratory capacity, and tube formation. This recovery was Nrf2-activation-dependent, since cotreatment with Nrf2 inhibitor Brusatol could abolish the rejuvenative effects of ESC-Exos. Further study revealed that miR-200a was highly enriched in ESC-Exos and played a crucial role in ESC-Exos-mediated rejuvenation through downregulating Keap1, which negatively regulates Nrf2 expression.

Conclusions

ESC-Exos ameliorate endothelial senescence by activating Nrf2 and recover aging-related angiogenic dysfunction, thereby accelerating wound healing in aged mice. ESC-Exos might be a natural nano-biomaterial for aging-related diseases therapy.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1253-6) contains supplementary material, which is available to authorized users.

Ginsenoside Re inhibits PDGF-BB-induced VSMC proliferation via the eNOS/NO/cGMP pathway

Ginsenoside Re (GS-Re), which is a major monomeric member of the ginseng trialcohol saponin family, is one of the main active components of ginseng and plays an important role in protecting the cardiovascular system. Here, we report a novel function by which GS-Re regulates the eNOS/NO/cGMP pathway, which affects the platelet-derived growth factor-BB (PDGF-BB)-induced proliferation of vascular smooth muscle cells (VSMCs). GS-Re inhibited PDGF-BB-induced VSMC proliferation in a concentration-dependent manner without cytotoxicity, and the endothelial nitric oxide synthase (eNOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) antagonized the antiproliferative effect of GS-Re. The flow cytometry analysis suggested that GS-Re regulates VSMC proliferation by influencing the cell cycle transition from G0/G1 to S phase and decreasing the expression of G0/G1-specific regulatory proteins, including proliferating cell nuclear antigen (PCNA), cyclin D1, and CDK4, in PDGF-BB-treated VSMCs, consequently upregulating the protein expression of p21. After GS-Re treatment, the levels of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) and the phos-eNOS ^Ser1177/eNOS protein ratio were obviously increased. In addition, treatment with L-NAME blocked the eNOS/NO/cGMP signaling pathway, and the protein levels of PCNA, cyclin D1, and CDK4 were markedly increased in GS-Re-treated VSMCs, while p21 expression was decreased in PDGF-BB-induced VSMCs. Overall, these findings reveal that GS-Re can inhibit the proliferation of VSMCs through G0/G1 cell cycle arrest, which is closely related to eNOS/NO/cGMP pathway activation. The present results provide basic pharmacological evidence of the potential prevention and treatment of cardiovascular diseases by GS-Re.

The Effects of Cobalt Protoporphyrin IX and Tricarbonyldichlororuthenium (II) Dimer Treatments and Its Interaction with Nitric Oxide in the Locus Coeruleus of Mice with Peripheral Inflammation

Heme oxygenase 1 (HO-1) and carbon monoxide were shown to normalize oxidative stress and inflammatory reactions induced by neuropathic pain in the central nervous system, but their effects in the locus coeruleus (LC) of animals with peripheral inflammation and their interaction with nitric oxide are unknown. In wild-type (WT) and knockout mice for neuronal (NOS1-KO) or inducible (NOS2-KO) nitric oxide synthases with inflammatory pain induced by complete Freund’s adjuvant (CFA), we assessed: (1) antinociceptive actions of cobalt protoporphyrin IX (CoPP), an HO-1 inducer; (2) effects of CoPP and tricarbonyldichlororuthenium(II) dimer (CORM-2), a carbon monoxide-liberating compound, on the expression of HO-1, NOS1, NOS2, CD11b/c, GFAP, and mitogen-activated protein kinases (MAPK) in the LC. CoPP reduced inflammatory pain in different time-dependent manners in WT and KO mice. Peripheral inflammation activated astroglia in the LC of all genotypes and increased the levels of NOS1 and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK 1/2) in WT mice. CoPP and CORM-2 enhanced HO-1 and inhibited astroglial activation in all genotypes. Both treatments blocked NOS1 overexpression, and CoPP normalized ERK 1/2 activation. This study reveals an interaction between HO-1 and NOS1/NOS2 during peripheral inflammation and shows that CoPP and CORM-2 improved HO-1 expression and modulated the inflammatory and/or plasticity changes caused by peripheral inflammation in the LC.

Endothelial Cells: From Dysfunction Mechanism to Pharmacological Effect in Cardiovascular Disease

Endothelial cells (ECs) are the innermost layer of blood vessels that play important roles in homeostasis and vascular function. However, recent evidence suggests that the onset of inflammation and the production of reactive oxygen species impair the function of ECs and are a main factor in the development of cardiovascular disease (CVD). In this study, we investigated the effects of inflammatory markers, oxidative stress, and treatment on ECs in CVD patients. This review article is based on the material obtained from PubMed up to 2018. The key search terms used were "Cardiovascular Disease," "Endothelial Cell Dysfunction," "Inflammation," "Treatment," and "Oxidative Stress." The generation of reactive oxygen species (ROS) as well as reduced nitric oxide (NO) production by ECs impairs the function of blood vessels. Therefore, treatment of CVD patients leads to the expression of transcription factors activating anti-oxidant mechanisms and NO production. In contrast, NO production by inflammatory agents can cause ECs repair due to differentiation of endothelial progenitor cells (EPCs). Therefore, identifying the molecular pathways leading to the differentiation of EPCs through mediation of factors induced by inflammatory factors can be effective in regenerative medicine for ECs repair.

Knockout of receptor for advanced glycation end-products attenuates age-related renal lesions

Pro‐aging effects of endogenous advanced glycation end‐products (AGEs) have been reported, and there is increasing interest in the pro‐inflammatory and ‐fibrotic effects of their binding to RAGE (the main AGE receptor). The role of dietary AGEs in aging remains ill‐defined, but the predominantly renal accumulation of dietary carboxymethyllysine (CML) suggests the kidneys may be particularly affected. We studied the impact of RAGE invalidation and a CML‐enriched diet on renal aging. Two‐month‐old male, wild‐type (WT) and RAGE^−/− C57Bl/6 mice were fed a control or a CML‐enriched diet (200 μg CML/g_food) for 18 months. Compared to controls, we observed higher CML levels in the kidneys of both CML WT and CML RAGE^−/− mice, with a predominantly tubular localization. The CML‐rich diet had no significant impact on the studied renal parameters, whereby only a trend to worsening glomerular sclerosis was detected. Irrespective of diet, RAGE^−/− mice were significantly protected against nephrosclerosis lesions (hyalinosis, tubular atrophy, fibrosis and glomerular sclerosis) and renal senile apolipoprotein A‐II (ApoA‐II) amyloidosis (p < 0.001). A positive linear correlation between sclerosis score and ApoA‐II amyloidosis score (r = 0.92) was observed. Compared with old WT mice, old RAGE^−/− mice exhibited lower expression of inflammation markers and activation of AKT, and greater expression of Sod2 and SIRT1. Overall, nephrosclerosis lesions and senile amyloidosis were significantly reduced in RAGE^−/− mice, indicating a protective effect of RAGE deletion with respect to renal aging. This could be due to reduced inflammation and oxidative stress in RAGE^−/− mice, suggesting RAGE is an important receptor in so‐called inflamm‐aging.

Increased sFRP3 expression correlated to senescence of endothelial cells in the aging process of mice

Aging is tightly associated with various diseases, such as cardiovascular diseases; however, there is no effective biomarker to detect and evaluate the aging process in vivo. Therefore, it is critical to identify new aging biomarkers for earlier diagnose of aging-related diseases. This study investigated the profile of cytokines in serum samples of young and aged mice with the purpose of exploring new biomarkers that have remarkable alterations in aging. A solid-phase antibody array was used to screen 200 proteins in the mouse serum, among which 32 cytokines differentially expressed between young and aged mice were screened. The major proteins were secreted frizzled-related protein 3 (sFRP3), Fractalkine, IGFBP-5, IGFBP-6, etc. We select secreted frizzled-related protein 3 (sFRP3) in follow-up study. Then, enzyme-linked immunosorbent assay (ELISA) was used to detect the expression levels of sFRP3. Our results revealed that the expression levels of sFRP3 in serum samples from aged mice were significantly higher than those in samples from young mice. ELISA data were identical to those obtained by the antibody array. Our findings indicated that sFRP3 has remarkable significance in senescence. Furthermore, we detected sFRP3 level in culture supernatants of primary endothelial cells, and the variation trend of sFRP3 levels in culture supernatant was consistent with serum data. We also detected serum sFRP3 amounts in healthy young and elderly individuals. Interestingly, serum sFRP3 amounts in the elderly were significantly increased compared with those of young individuals.

Heme detoxification by heme oxygenase-1 reinstates proliferative and immune balances upon genotoxic tissue injury

Phenotypic changes of myeloid cells are critical to the regulation of premature aging, development of cancer, and responses to infection. Heme metabolism has a fundamental role in the regulation of myeloid cell function and activity. Here, we show that deletion of heme oxygenase-1 (HO-1), an enzyme that removes heme, results in an impaired DNA damage response (DDR), reduced cell proliferation, and increased cellular senescence. We detected increased levels of p16^INK4a, H2AXγ, and senescence-associated-β-galactosidase (SA-β-Gal) in cells and tissues isolated from HO-1-deficient mice. Importantly, deficiency of HO-1 in residential macrophages in chimeric mice results in elevated DNA damage and senescence upon radiation-induced injury. Mechanistically, we found that mammalian target of rapamycin (mTOR)/S6 protein signaling is critical for heme and HO-1-regulated phenotype of macrophages. Collectively, our data indicate that HO-1, by detoxifying heme, blocks p16^INK4a expression in macrophages, preventing DNA damage and cellular senescence.

Curcumin Inhibits Age-Related Vascular Changes in Aged Mice Fed a High-Fat Diet

Inhibiting the onset of arteriosclerotic disease, which has been increasing due to the westernized diet and aging, is a significant social challenge. Curcumin, a type of polyphenol, has anti-oxidative effects and anti-inflammatory action and is expected to treat and to have prophylactic effects on different diseases. In this study, we examined the effects of long-term administration of curcumin on vascular aging and chronic inflammation—the causes of arteriosclerotic disease. Eight-week-old C57BL/6J mice were fed with high fat diet (HFD) or 0.1% curcumin-mixed HFD (HFD + Cu) until 80 weeks old (n = 20 for each group). After the breeding, we examined the expression of antioxidant enzymes, heme oxygenase-1 (HO-1), oxidative stress, vascular aging, and inflammatory changes in the aorta. In the HFD group, oxidative stress increased with decreased sirt1 expression in the aorta followed by increased senescent cells and enhanced inflammation. Whereas in the HFD + Cu group, HO-1 was induced in the aorta with the suppression of oxidative stress. Additionally, it was shown that sirt1 expression in the aorta in the HFD + Cu group remained at a level comparable to that of the 8-week-old mice with suppression of increased senescent cells and enhanced inflammation. Consequently, disorders associated with HFD were resolved. These results suggest that curcumin might be a food with a prophylactic function against arteriosclerotic disease.