The Vasorelaxatory Effect of Nelumbo nucifera Spornioderm on Porcine Coronary Artery.

Endothelium dysfunction is a hallmark of cardiovascular disease (CVD) and is characterized by loss of homeostasis. Nitric oxide deprivation, unbalanced production of vasoactive factors such as thromboxane, endothelium-derived hyperpolarizing factor (EDHF) and production of reactive oxygen species are known as early indicators of CVD. Bioavailability of nitric oxide, antioxidative activity, and regulation of ionic homeostasis are the key targets for prevention of CVD. In this study, we investigated the vasorelaxant action of Nelumbo nucifera extract as well as the underlying mechanism using porcine coronary artery. Vasorelaxant effect of extracts from four different parts of Nelumbo nucifera (flower, leaf, seed, and spornioderm) was tested. Among them, extracts from Nelumbo nucifera spornioderm (NNS) showed the strongest endothelium-dependent vasorelaxation. Vasorelaxation effect of NNS was markedly reduced by inhibitor of endothelial nitric oxide synthase (eNOS), inhibitor of Phosphoinositide 3 kinase (PI3K) and inhibitor of soluble guanylyl cyclase (sGC), but unaffected by inhibitor of cyclooxygenase and EDHF. NNS induced concentration-dependent phosphorylation of eNOS in endothelial cells. Altogether, our study demonstrated that NNS is a potent endothelium-dependent vasodilator, mediated by PI3K-eNOS-sGC pathway. Our present findings showed NNS as a potential herbal candidate for the therapy of cardiovascular diseases associated with endothelial dysfunction and atherosclerosis.

Activated factor X stimulates atrial endothelial cells and tissues to promote remodelling responses through AT1R/NADPH oxidases/SGLT1/2.

AIMS: Atrial fibrillation (AF), the most common cardiac arrhythmia favouring ischemic stroke and heart failure involves left atrial remodelling, fibrosis and a complex interplay between cardiovascular risk factors. This study examined whether activated factor X (FXa) induces pro-remodelling and pro-fibrotic responses in atrial endothelial cells (AECs) and human atrial tissues and determined the underlying mechanisms. METHODS AND RESULTS: AECs collected from porcine hearts and human right atrial appendages (RAA) from patients undergoing heart surgery. Protein expression levels were assessed by Western blot and immunofluorescence staining, mRNA levels by RT-qPCR, formation of reactive oxygen species (ROS) and NO using fluorescent probes, thrombin and angiotensin II generation by specific assays, fibrosis by Sirius red staining and senescence by senescence-associated beta-galactosidase (SA-ß-gal) activity. In AECs, FXa increased ROS formation, senescence (SA-ß-gal activity, p53, p21), angiotensin II generation and the expression of pro-inflammatory (VCAM-1, MCP-1), pro-thrombotic (tissue factor), pro-fibrotic (TGF-ß and collagen-1/3a) and pro-remodelling (MMP-2/9) markers whereas eNOS levels and NO formation were reduced. These effects were prevented by inhibitors of FXa but not thrombin, protease-activated receptors antagonists (PAR-1/2) and inhibitors of NADPH oxidases, ACE, AT1R, SGLT1/SGLT2. FXa also increased expression levels of ACE1, AT1R, SGLT1/2 proteins which were prevented by SGLT1/2 inhibitors. Human RAA showed tissue factor mRNA levels that correlated with markers of endothelial activation, pro-remodelling and pro-fibrotic responses and SGLT1/2 mRNA levels. They also showed protein expression levels of ACE1, AT1R, p22phox, SGLT1/2, and immunofluorescence signals of nitrotyrosine and SGLT1/2 colocalized with those of CD31. FXa increased oxidative stress levels which were prevented by inhibitors of the AT1R/NADPH oxidases/SGLT1/2 pathway. CONCLUSION: FXa promotes oxidative stress triggering premature endothelial senescence and dysfunction associated with pro-thrombotic, pro-remodelling and pro-fibrotic responses in AECs and human RAA involving the AT1R/NADPH oxidases/SGLT1/2 pro-oxidant pathway. Targeting this pathway may be of interest to prevent atrial remodelling and the progression of atrial fibrillation substrate.

Potential of dapagliflozin to prevent vascular remodeling in the rat carotid artery following balloon injury.

BACKGROUND AND AIMS: Sodium-glucose co-transporter 2 (SGLT2) inhibitors have been shown to reduce the risk of cardiovascular events independently of glycemic control. However, the possibility that SGLT2 inhibitors improve vascular restenosis is unknown. The aim of this study was to examine whether dapagliflozin could prevent neointima thickening following balloon injury and, if so, to determine the underlying mechanisms. METHODS: Saline, dapagliflozin (1.5 mg/kg/day), or losartan (30 mg/kg/day) was administered orally for five weeks to male Wistar rats. Balloon injury of the left carotid artery was performed a week after starting the treatment and rats were sacrificed 4 weeks later. The extent of neointima was assessed by histomorphometric and immunofluorescence staining analyses. Vascular reactivity was assessed on injured and non-injured carotid artery rings, changes of target factors by immunofluorescence, RT-qPCR, and histochemistry. RESULTS: Dapagliflozin and losartan treatments reduced neointima thickening by 32 % and 27 %, respectively. Blunted contractile responses to phenylephrine and relaxations to acetylcholine and down-regulation of eNOS were observed in the injured arteries. RT-qPCR investigations indicated an increased in gene expression of inflammatory (IL-1beta, VCAM-1), oxidative (p47phox, p22phox) and fibrotic (TGF-beta1) markers in the injured carotid. While these changes were not affected by dapagliflozin, increased levels of AT1R and NTPDase1 (CD39) and decreased levels of ENPP1 were observed in the restenotic carotid artery of the dapagliflozin group. CONCLUSIONS: Dapagliflozin effectively reduced neointimal thickening. The present data suggest that dapagliflozin prevents restenosis through interfering with angiotensin and/or extracellular nucleotides signaling. SGLT2 represents potential new target for limiting vascular restenosis.

COVID-19 promotes endothelial dysfunction and thrombogenicity: role of proinflammatory cytokines/SGLT2 prooxidant pathway.

BACKGROUND: COVID-19 is associated with an increased risk of cardiovascular complications. Although cytokines have a predominant role in endothelium damage, the precise molecular mechanisms are far from being elucidated. OBJECTIVES: The present study hypothesized that inflammation in patients with COVID-19 contributes to endothelial dysfunction through redox-sensitive SGLT2 overexpression and investigated the protective effect of SGLT2 inhibition by empagliflozin. METHODS: Human plasma samples were collected from patients with acute, subacute, and long COVID-19 (n = 100), patients with non-COVID-19 and cardiovascular risk factors (n = 50), and healthy volunteers (n = 25). Porcine coronary artery endothelial cells (ECs) were incubated with plasma (10%). Protein expression levels were determined using Western blot analyses and immunofluorescence staining, mRNA expression by quantitative reverse transcription-polymerase chain reaction, and the level of oxidative stress by dihydroethidium staining. Platelet adhesion, aggregation, and thrombin generation were determined. RESULTS: Increased plasma levels of interleukin (IL)-1ß, IL-6, tumor necrosis factor-α, monocyte chemoattractant protein-1, and soluble intercellular adhesion molecule-1 were observed in patients with COVID-19. Exposure of ECs to COVID-19 plasma with high cytokines levels induced redox-sensitive upregulation of SGLT2 expression via proinflammatory cytokines IL-1ß, IL-6, and tumor necrosis factor-α which, in turn, fueled endothelial dysfunction, senescence, NF-κB activation, inflammation, platelet adhesion and aggregation, von Willebrand factor secretion, and thrombin generation. The stimulatory effect of COVID-19 plasma was blunted by neutralizing antibodies against proinflammatory cytokines and empagliflozin. CONCLUSION: In patients with COVID-19, proinflammatory cytokines induced a redox-sensitive upregulation of SGLT2 expression in ECs, which in turn promoted endothelial injury, senescence, platelet adhesion, aggregation, and thrombin generation. SGLT2 inhibition with empagliflozin appeared as an attractive strategy to restore vascular homeostasis in COVID-19.

γ-Oryzanol ameliorates fine dust-induced premature endothelial senescence and dysfunction via attenuating oxidative stress.

Various cardiovascular diseases are associated with endothelial senescence, and a recent study showed that fine dust (FD)-induced premature endothelial senescence and dysfunction is associated with increased oxidative stress. The aim of the present study was to investigate protective effect of rice bran extract (RBE) and its major component of γ-Oryzanol (γ-Ory) against FD-induced premature endothelial senescence. Porcine coronary artery endothelial cells (PCAECs) were treated with FD alone or with RBE or γ-Ory. Senescence-associated ß-galactosidase (SA-ß-gal) activity, expression of cell cycle regulatory proteins, and oxidative stress levels were evaluated. The results indicated that SA-ß-gal activity in the FD-treated PCAECs was attenuated by RBE and γ-Ory. Additionally, γ-Ory inhibited FD-induced cell cycle arrest, restored cell proliferation, and reduced the expression of cell cycle regulatory proteins. γ-Ory also inhibited oxidative stress and prevented senescence-associated NADPH oxidase and LAS activity in FD-exposed ECs suggesting that γ-Ory could protect against FD-induced ECs senescence and dysfunction.

Taxifolin as a Major Bioactive Compound in the Vasorelaxant Effect of Different Pigmented Rice Bran Extracts.

Cardiovascular disease is one of the leading causes of morbidity and mortality in recent years. The intake of polyphenol rich diets has been associated with improved cardiovascular function and reduced cardiovascular risks. Oryza sativa L. is one of the most common cereals worldwide. Rice bran, a byproduct of the rice milling process, contains many bioactive ingredients, including polyphenols, polysaccharides, proteins, and micronutrients. It is also consumed as a healthy diet in the form of rice bran oil and powder in many Asian countries like Japan, South Korea, and India for its several health benefits as a natural antioxidant. Thus, this study evaluated the vasorelaxant effect of ethanolic extracts of brown, green, red, and black rice bran and investigated its underlying vasorelaxant mechanism. Among the four rice bran extracts (RBEs) examined, the red rice bran extract (RRBE) had a strong endothelium-dependent vasorelaxant effect, which was markedly prevented by N-ω-nitro-L-arginine [endothelial nitric oxide synthase (eNOS) inhibitor], wortmannin [phosphoinositide-3 kinase (PI3K) inhibitor], and 1H-[1,2,4]oxadiazole[4,3-alpha]quinoxalin-1-one (inhibitor of guanylate cyclase). Likewise, RRBE induced the phosphorylation of eNOS and Src in cultured endothelial cells, thereby stimulating NO formation. Altogether, these findings propose that RRBE induces endothelium-dependent relaxation, involving at least in part, NO-mediated signaling through the PI3K/eNOS pathway. Further, LC-PDA analysis conducted on the four RBEs also revealed that RRBE highly contained taxifolin, which is an active flavanonol that induces endothelium-dependent vasorelaxation, compared to other RBEs. Subsequently, the underlying mechanism of taxifolin was assessed through vascular reactivity studies with pharmacological inhibitors similar to that of RRBE. These findings deciphered a distinct difference in vasorelaxant effects between RRBE and the other RBEs. We also observed that RRBE induced a potent endothelium-dependent NO-mediated relaxation in coronary artery rings, which involved the Src/PI3K pathway that activates eNOS. Additionally, taxifolin exhibited, at least in part, similar vasoprotective effects of RRBE. Therefore, we propose that RRBE may serve as natural sources of functional phytochemicals that improve cardiovascular diseases associated with disturbed NO production and endothelial dysfunction.

Effects of polystyrene nanoplastics on endothelium senescence and its underlying mechanism.

Global plastic use has increased rapidly, and environmental pollution associated with nanoplastics (NPs) has been a growing concern recently. However, the impact and biological mechanism of NPs on the cardiovascular system are not well characterized. This study aimed to assess the possibility that NPs exposure promotes premature endothelial cell (EC) senescence in porcine coronary artery ECs and, if so, to elucidate the underlying mechanism. Treatment of ECs with NPs promoted the acquisition of senescence markers, senescence-associated ß-galactosidase activity, and p53, p21, and p16 protein expression, resulting in the inhibition of proliferation. In addition, NPs impaired endothelium-dependent vasorelaxation associated with decreased endothelial nitric oxide synthase (eNOS) expression. NPs enhanced reactive oxygen species formation in ECs, and increased oxidative stress levels were associated with the induction of NADPH oxidases expression, followed by the subsequent downregulation of Sirt1 expression. The characteristics of EC senescence and dysfunction caused by NPs are prevented by an antioxidant (N-acetylcysteine), an NADPH oxidase inhibitor (apocynin), and a Sirt1 activator (resveratrol). These findings indicate that NPs induced premature EC senescence, at least in part, through the redox-sensitive eNOS/Sirt1 signaling pathway. This study suggested the effects and underlying mechanism of NPs on the cardiovascular system, which may provide pharmacological targets to prevent NPs-associated cardiovascular diseases.

Endothelium-Dependent Relaxation Effects of Actinidia arguta Extracts in Coronary Artery: Involvement of eNOS/Akt Pathway.

Cardiovascular diseases (CVD) are the major cause of death globally. Bioavailability of nitric oxide, antioxidative activity, and regulation of ionic homeostasis are the key targets for prevention of CVD. Actinidia arguta (AA) has shown promising effect for anticancer, anti-hypercholesterolemia, and antioxidant agents. However, the vascular effect of AA remains unclear. Therefore, we investigated the vascular relaxation of AA extract as well as the underlying mechanisms. Vascular reactivity was assessed in organ baths using porcine coronary arteries and antioxidant properties were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH). Methanol extract of AA stem (AASE) induced significantly vasorelaxation of porcine coronary artery and its effects is endothelium-dependent without cytotoxicity effects. In addition, ASSE scavenged reactive oxygen species (ROS) in vitro and strongly inhibited NADPH-oxidase activity, which is major source of ROS in vasculature. AASE strongly and dose-dependently activate endothelial nitric oxide synthase (eNOS), the major vascular protective enzyme, and Akt, the upstream signaling protein of eNOS, in porcine coronary artery endothelial cell. Altogether, these results have demonstrated that AASE is a potent endotheliumdependent vasodilator and this effect was involved in, at least in part, Akt/eNOS/NO pathway with strong anti-oxidant properties. The present findings indicate that AA stem could be a valuable candidate of herbal medicine for cardiovascular diseases associated with endothelial dysfunction and atherosclerosis.

Vasorelaxant Effect of Boesenbergia rotunda and Its Active Ingredients on an Isolated Coronary Artery.

Cardiovascular diseases are a major cause of death in developed countries. The regulation of vascular tone is a major approach to prevent and ameliorate vascular diseases. As part of our ongoing screening for cardioprotective natural compounds, we investigated the vasorelaxant effect of rhizomes from Boesenbergia rotunda (L.) Mansf. [Boesenbergia pandurata (Roxb.) Schltr.] used as a spice and herbal medicine in Asian countries. The methanol extract of B. rotunda rhizomes (BRE) exhibited significant vasorelaxation effects ex vivo at EC50 values of 13.4 ± 6.1 µg/mL and 40.9 ± 7.9 µg/mL, respectively, with and without endothelium in the porcine coronary artery ring. The intrinsic mechanism was evaluated by treating with specific inhibitors or activators that typically affect vascular reactivity. The results suggested that BRE induced relaxation in the coronary artery rings via an endothelium-dependent pathway involving NO-cGMP, and also via an endothelium-independent pathway involving the blockade of Ca2+ channels. Vasorelaxant principles in BRE were identified by subsequent chromatographic methods, which revealed that flavonoids regulate vasorelaxant activity in BRE. One of the flavonoids was a Diels-Alder type adduct, 4-hydroxypanduratin A, which showed the most potent vasorelaxant effect on porcine coronary artery with an EC50 of 17.8 ± 2.5 µM. Our results suggest that rhizomes of B. rotunda might be of interest as herbal medicine against cardiovascular diseases.

Fine air pollution particles induce endothelial senescence via redox-sensitive activation of local angiotensin system.

Fine dust (FD) is a form of air pollution and is responsible for a wide range of diseases. Specially, FD is associated with several cardiovascular diseases (CVDs); long-term exposure to FD was shown to decrease endothelial function, but the underlying mechanism remains unclear. We investigated whether exposure to FD causes premature senescence-associated endothelial dysfunction in endothelial cells (ECs) isolated from porcine coronary arteries. The cells were treated with different concentrations of FD and senescence associated-beta galactosidase (SA-ß-gal) activity, cell cycle progression, expression of endothelial nitric oxide synthase (eNOS), oxidative stress level, and vascular function were evaluated. We found that FD increased SA-ß-gal activity, caused cell cycle arrest, and increased oxidative stress, suggesting the premature induction of senescence; on the other hand, eNOS expression was downregulated and platelet aggregation was enhanced. FD exposure impaired vasorelaxation in response to bradykinin and activated the local angiotensin system (LAS), which was inhibited by treatment with the antioxidant N-acetyl cysteine (NAC) and angiotensin II receptor type 1 (AT1) antagonist losartan (LOS). NAC and LOS also suppressed FD-induced SA-ß-gal activity, increased EC proliferation and eNOS expression, and improved endothelial function. These results demonstrate that FD induces premature senescence of ECs and is associated with increased oxidative stress and activation of LAS. This study can serve as a pharmacological target for prevention and/or treatment of air pollution-associated CVD.

Vascular Protection by Ethanol Extract of Morus alba Root Bark: Endothelium-Dependent Relaxation of Rat Aorta and Decrease of Smooth Muscle Cell Migration and Proliferation.

Morus alba (white mulberry) is native to the northern part of Korea and popularly used as a traditional medicine due to its numerous health benefits against human's disease. However, the possibility that M. alba may also affect the cardiovascular system remains unexplored. This study sought to investigate the vascular protective effects of the root bark extract of M. alba (MAE). Vascular reactivity was performed in organ baths using isolated rat thoracic aorta, while platelet derived growth factor (PDGF) induced proliferation and migration of vascular smooth muscle cells (VSMCs) were studied by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and wound healing assay, respectively. MAE evoked a concentration dependent vasorelaxation following endothelium-dependent pathway. However, vessel relaxations in response to MAE were markedly reduced after endothelium removal; treatment of endothelial nitric oxide synthase inhibitor, guanylyl cyclase inhibitor, and nonspecific potassium channel inhibitor, however, was not altered by cyclooxygenase inhibitor. Furthermore, MAE also significantly blunted contractile response to vasoconstrictor agent, phenylephrine. Taken together, the current evidence revealed that MAE is a potent endothelium-dependent vasodilator and this effect was involved in, at least in part, nitric oxide cyclic-guanosine monophosphate (NO-cGMP) pathway in combination with potassium (K+) channel activation. Moreover, MAE inhibited proliferation and migration of VSMCs induced by PDGF. Therefore, MAE could be a promising candidate of natural medicine for preventing and controlling cardiovascular diseases linked with endothelial dysfunction.

Combination of Garcinia cambogia Extract and Pear Pomace Extract Additively Suppresses Adipogenesis and Enhances Lipolysis in 3T3-L1 Cells.

BACKGROUND: Inhibition of adipogenesis has been a therapeutic target for reducing obesity and obesity-related disorders such as diabetes, hypertension, atherosclerosis, and cancer. For decades, anti-adipogenic potential of many herbal extracts has been investigated. One example is Garcinia cambogia extract (GE) containing (-)-hydroxycitric acid as an active ingredient. GE is currently marketed as a weight loss supplement, used alone or with other ingredients. Pear pomace extract (PE), another natural product, has been also shown to have anti-adipogenic activity in a recent report. OBJECTIVE: It was tested if the mixture of PE and GE (MIX) would produce more effective anti-adipogenic activity than PE or GE alone. MATERIALS AND METHODS: Differentiation of 3T3-L1 preadipocyte was induced by adding insulin, dexamethasone, and isobutylmethylxanthine and lipid accumulation was measured by Oil Red O staining. Cellular markers for adipogenesis and lipolysis such as CCAAT/enhancer binding protein (C/EBP-α), peroxisome proliferator-activated receptor gamma (PPAR-γ), fatty acid synthase (FAS), and hormone-sensitive lipase (HSL) was measured using immunocytochemistry. RESULTS: MIX, compared to PE or GE alone, showed greater inhibition of lipid accumulation. Furthermore, MIX reduced the expression of adipogenesis-related factors C/EBP-α, PPAR-γ, and FAS more than PE or GE alone did. In contrast, the expression of HSL the enzyme required for lipolysis was further enhanced in MIX-treated adipocytes compared to the PE or GE alone treated groups. CONCLUSIONS: Anti-adipogenic effect of PE and GE appears synergistic, and the MIX may be a useful therapeutic combination for the treatment of obesity and obesity-related diseases. SUMMARY: PE and GE efficiently inhibited adipocyte differentiation by suppressing the expression of adipogenic transcription factor CEBP-α and PPAR-γ.PE and GE significantly decreased the expression of adipogenic enzyme FAS.PE and GE increased the expression of lipid degrading enzyme HSL.Mixture of PE and GE exhibited additive or moderately synergistic effect on adipocyte differentiation and lipid accumulation. Abbreviations used: CEBP-a: CCAT/enhancer binding protein alpha, CI: Combination Index, FAS: Fatty acid synthase, GE: Garcinia cambogia extract, HSL: Hormone sensitive lipase, PE: Pear pomace extract, PPAR-γ: Peroxisome proliferator-activated receptor gamma.