Vascular hyperpolarization in human physiology and cardiovascular risk conditions and disease

Vascular actions of Ang 1-7 and Ang 1-8 through EDRFs and EDHFs in non-diabetes and diabetes mellitus

The renin-angiotensin system (RAS) plays a pivotal role in regulating vascular homeostasis, while angiotensin 1-8 (Ang 1-8) traditionally dominates as a vasoconstrictor factor. However, the discovery of angiotensin 1-7 (Ang 1-7) and Ang 1-8 has revealed counter-regulatory mechanisms mediated through endothelial-derived relaxing factors (EDRFs) and endothelial-derived hyperpolarizing factors (EDHFs). This review delves into the vascular actions of Ang 1-7 and Ang 1-8 in both non-diabetes mellitus (non-DM) and diabetes mellitus (DM) conditions, highlighting their effects on vascular endothelial cell (VECs) function as well. In a non-DM vasculature context, Ang 1-8 demonstrate dual effect including vasoconstriction and vasodilation, respectively. Additionally, Ang 1-7 induces vasodilation upon nitric oxide (NO) production as a prominent EDRFs in distinct mechanisms. Further research elucidating the precise mechanisms underlying the vascular actions of Ang 1-7 and Ang 1-8 in DM will facilitate the development of tailored therapeutic interventions aimed at preserving vascular health and preventing cardiovascular complications.

LDL-c/HDL-c Ratio and NADPH-Oxidase-2-Derived Oxidative Stress as Main Determinants of Microvascular Endothelial Function in Morbidly Obese Subjects

The identification of obese subjects at higher risk for cardiovascular disease (CVD) is required. We aimed to characterize determinants of endothelial dysfunction, the initial step to CVD, in small omental arteries of visceral fat from obese subjects. The influences of analytical parameters and vascular oxidative stress mediated by NADPH-oxidase-2 (NOX2) on endothelial function were determined. Specimens were obtained from 51 obese subjects undergoing bariatric surgery and 14 non-obese subjects undergoing abdominal surgery. Obese subjects displayed reduced endothelial vasodilation to bradykinin (BK). Endothelial vasodilation (pEC50 for BK) among obese subjects was significantly and negatively associated with low-density lipoprotein cholesterol (LDL-c)/high-density lipoprotein cholesterol (HDL-c) ratio (r = -0.510, p = 0.0001) in both women and men, while other metabolic parameters and comorbidities failed to predict endothelial function. The vascular expression of NOX2 was upregulated in obese subjects and was related to decreased endothelial vasodilation (r = -0.529, p = 0.0006, n = 38) and increased oxidative stress (r = 0.783, p = 0.0044, n = 11) in arterial segments. High LDL-c/HDL-c (>2) and high NOX2 (above median) were independently associated with reduced endothelial function, but the presence of both conditions was related to a further impairment. Concomitant elevated LDL-c/HDL-c ratio and high vascular expression of NOX2 would exacerbate endothelial impairment in obesity and could reveal a deleterious profile for cardiovascular outcomes among obese subjects.

Ion channels in stem cells and their roles in stem cell biology and vascular diseases

Stem cell therapy may be a promising option for the treatment of vascular diseases. In recent years, significant progress has been made in stem cell research, especially in the mechanism of stem cell activation, homing and differentiation in vascular repair and reconstruction. Current research on stem cells focuses on protein expression and transcriptional networks. Ion channels are considered to be the basis for the generation of bioelectrical signals, which control the proliferation, differentiation and migration of various cell types. Although heterogeneity of multiple ion channels has been found in different types of stem cells, it is unclear whether the heterogeneous expression of ion channels is related to different cell subpopulations and/or different stages of the cell cycle. There is still a long way to go in clinical treatment by using the regulation of stem cell ion channels. In this review, we reviewed the main ion channels found on stem cells, their expression and function in stem cell proliferation, differentiation and migration, and the research status of stem cells' involvement in vascular diseases.

Low-intensity pulsed ultrasound prevents angiotensin II-induced aortic smooth muscle cell phenotypic switch via hampering miR-17-5p and enhancing PPAR-γ

Vascular events can trigger a pathological phenotypic switch in vascular smooth muscle cells (VSMCs), decreasing and disrupting the plasticity and diversity of vascular networks. The development of novel therapeutic approaches is necessary to prevent these changes. We aimed to investigate the effects and associated mechanisms of low-intensity pulsed ultrasound (LIPUS) irradiation on the angiotensin II (AngII)-induced phenotypic switch in VSMCs. In vivo, AngII was infused subcutaneously for 4 weeks to stimulate vascular remodeling in mice, and LIPUS irradiation was applied for 20 min every 2 days for 4 weeks. In vitro, cultured rat aortic VSMCs (RAVSMCs) were pretreated once with LIPUS irradiation for 20 min before 48-h AngII stimulation. Our results showed that LIPUS irradiation prevents AngII-induced vascular remodeling of the whole wall artery without discriminating between adventitia and media in vivo and RAVSMC phenotypic switching in vitro. LIPUS irradiation downregulated miR-17-5p expression and upregulated peroxisome proliferator-activated receptor gamma (PPAR-γ) expression. The PPAR-γ activator rosiglitazone could mimic the favorable effects of LIPUS irradiation on AngII-treated RAVSMCs. In contrast, GW9662 could impede the LIPUS-mediated downregulation of RAVSMC proliferation and inflammation under AngII stimulation conditions in vivo and in vitro. Also, the miR-17-5p agomir has the same effects as GW9662 in vitro. Besides, the inhibitory effects of GW9662 against the anti-remodeling effects of LIPUS irradiation in AngII-induced RAVSMCs could be blocked by pretreatment with the miR-17-5p antagomir. Overall, LIPUS irradiation prevents AngII-induced RAVSMCs phenotypic switching through hampering miR-17-5p and enhancing PPAR-γ, suggesting a new approach for the treatment of vascular disorders.

Nwokocha C, Bórquez J, Simirgiotis MJ, Norambuena I, Chiong M, Paredes A. Polyphenolic Composition and Hypotensive Effects of Parastrephia quadrangularis (Meyen) Cabrera in Rat

Parastrephia quadrangularis (Pq), commonly called "Tola", is widely used in folk medicine in the Andes, including for altitude sickness. In this study, polyphenolic composition was determined, and hypotensive effects were measured; the ethnopharmacological use as hypotensive was related to the presence of phenolic compounds. For this purpose, male Sprague-Dawley rats (6 to 8 weeks of age, 160 to 190 g) were fed Pq extract (10 to 40 mg/kg) for 10 days through gavage. Blood pressures and heart rate were significantly (p < 0.01) reduced in normotensive rats receiving Pq extract (40 mg/kg body weight). Pq extract induced a negative inotropic effect, and endothelium-dependent vasodilation mediated by nitric oxide (NO). Furthermore, preincubation with Pq extract significantly decreased the cytosolic calcium on vascular smooth muscle cells A7r5 in response to L-phenylephrine (PE). Seven metabolites were isolated from the Pq extract, but three flavonoids (10^-4 M) showed similar vasodilation to the extract in intact rat aorta as follows: 5,3',4'-trihydroxy-7-methoxyflavanone (2); 3,5,4'-trihydroxy-7,8,3'-trimethoxyflavone (6); and 5,4'-dihydroxy-3,7,8,3'-tetramethoxyflavone (7). The Pq extract and compounds 2 and 7 significantly (p < 0.05) reduced the contraction to Bay K8644 (10 nM, an agonist of Ca_V1.2 channels). Administration of Pq decreased cardiac contractility and increased endothelium-dependent and -independent vasodilation.

Vardenafil and cilostazol can improve vascular reactivity in rats with diabetes mellitus and rheumatoid arthritis co-morbidity

Endothelial dysfunction and vascular reactivity defects secondary to metabolic and immunological disorders carry risk of serious cardiovascular complications. Here, the effects of the phosphodiesterase (PDE) inhibitors vardenafil and cilostazol were examined against rheumatoid arthritis (RA)/diabetes mellitus (DM)-co-morbidity-induced endothelial dysfunction and vascular reactivity defects. After setting of RA/DM-co-morbidity model, rats were divided into a normal control group, an RA/DM-co-morbidity group, and two treatment groups receiving oral vardenafil (10 mg/kg/day) and cilostazol (30 mg/kg/day) for 21 days after RA/DM-co-morbidity induction. Aorta was isolated for biochemical estimations of the pro-inflammatory vasoconstrictor molecules angiotensin-II (Ang-II) and endothelin-1 (ET-1), the adhesion molecules P-selectin and vascular cell adhesion molecule-1 (VCAM-1), the energy sensor adenosine-5'-monophosphate-activated protein kinase (AMPK), and the vasodilator anti-inflammatory molecule vasoactive intestinal peptide (VIP) using enzyme-linked immunosorbent assay (ELISA) and western blot analysis. Immunohistochemical estimations of endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase (MMP)-2 were performed coupled with histopathological examination using routine hematoxylin and eosin (H&E) and special Masson trichrome staining. The in vitro study was conducted using aortic strips where cumulative concentration response curves were done for the endothelium-dependent relaxing factor acetylcholine and the endothelium-independent relaxing factor sodium nitroprusside after submaximal contraction with phenylephrine. Vardenafil and cilostazol significantly improved endothelial integrity biomarkers in vivo supported with histopathological findings in addition to improved vasorelaxation in vitro. Apart from their known PDE inhibition, up-regulation of vascular AMPK and eNOS coupled with down-regulation of Ang-II, ET-1, P-selectin, VCAM-1 and MMP-2 may explain vardenafil and cilostazol protective effect against RA/DM-co-morbidity-induced endothelial dysfunction and vascular reactivity defects.

Follicle-stimulating hormone, but not cardiorespiratory fitness, is associated with flow-mediated dilation with advancing menopausal stage

OBJECTIVE

The aim of the study was to evaluate if there are differences in endothelial function before and after acute exercise in women at different menopausal stages with high and low cardiorespiratory fitness.

METHODS

Participants were healthy high-fit premenopausal (n = 11), perimenopausal (n = 12), and postmenopausal women (n = 13) and low-fit perimenopausal (n = 7) and postmenopausal women (n = 8). Brachial artery flow-mediated dilation (FMD) was measured before and after acute moderate intensity exercise. FMD was calculated as (Diameterpeak-Diameterbaseline)/ Diameterbaseline) × 100. Differences between high-fit women and between high- and low-fit perimenopausal and postmenopausal women were assessed with repeated-measure ANOVAs. Relations with FMD were assessed with Pearson correlations.

RESULTS

FMD was reduced with progressive menopausal stage in high-fit women (P = 0.005) and was lower in perimenopausal compared to postmenopausal women (P = 0.047). FMD was lower in high-fit compared to low-fit women (P = 0.006) and there was no relation between FMD and VO2peak (P > 0.05). There was an inverse relation between FMD and follicle-stimulating hormone (P < 0.05), but not estradiol (P > 0.05).

CONCLUSIONS

These data suggest that endothelial function is lower with progressive menopausal stage in women with high cardiorespiratory fitness; that FMD is lower in women with higher cardiorespiratory fitness; and that FSH, but not estradiol, is associated with FMD.

An overview of the biologic effects of omega-6 oxylipins in humans

Oxylipins are lipid mediators produced from polyunsaturated fatty acid (PUFA) metabolism, and are thought to be a molecular explanation for the diverse biological effects of PUFAs. Like PUFAs, oxylipins are distinguished by their omega-6 (n6) or omega-3 (n3) chemistry. We review the use of n6 oxylipins as biomarkers of disease and their use in diagnosis and risk assessment. We show cases where oxylipins derived from linoleate (LA) or arachidonate (AA) produced by the activities of lipoxygenase, cyclooxygenase, epoxygenase, ω/ω-1 hydroxylase, and autooxidation are useful as biomarkers or risk markers. HODEs, KODEs, EpOMEs, DiHOMEs, and other metabolites of LA as well as prostanoids, HETEs, KETEs, EpETrEs, and DiHETrEs, and other metabolites of AA were useful for understanding the different signaling environments in conditions from traumatic brain injury, to major coronary events, dyslipidemia, sepsis, and more. We next evaluate interventions that alter the concentrations of n6 oxylipins in plasma. We note the utility and response of each plasma fraction, and the generally increasing utility from the non-esterified, to the esterified, to the lipoprotein fractions. Finally, we review the effects which are specifically related to n6 oxylipins and most likely to be beneficial. Both n6 and n3 oxylipins work together in an exceedingly complex matrix to produce physiological effects. This overview should provide future investigators with important perspectives for the emerging utility of n6 oxylipins as products of n6 PUFAs in human health.

Hypoxia-inducible factor 1a induces phenotype switch of human aortic vascular smooth muscle cell through PI3K/AKT/AEG-1 signaling

To date, hypoxia-inducible factor 1a (HIF-1a) and astrocyte elevated gene-1 (AEG-1) have been involved in the proliferation, migration and morphological changes of vascular smooth muscle cells. However, the potential relationship of HIF-1a-AEG-1 pathway in human aortic smooth muscle cell (HASMC) has not been reported. In the present study, in-vitro assays were utilized to explore the potential impact of HIF-1a-AEG-1 signaling on HASMC phenotype. Here, we found that HIF-1a expression was up-regulated in the media of thoracic aortic dissection tissues as compared with normal aortic tissues, and was associated with increased apoptotic SMCs and decreased AEG-1 expression. Mechanically, hypoxia promoted the expression of HIF-1a by PI3K-AKT pathway in HASMCs; HIF-1a further suppressed the expressions of AEG-1, a-SMA and SM22a, and promoted osteopontin (OPN) expression. Functionally, HIF-1a inhibited the proliferation and migration of HASMCs. However, si-HIF-1a or Akt inhibitor abrogated HIF-1a-mediated related expressions and biological effects above. In conclusion, HIF-1a induces HASMC phenotype switch, and closely related to PI3K/AKT and AEG-1 signaling, which may provide new avenues for the prevention and treatment of aortic dissection diseases.

Regulation of vascular tone homeostasis by NO and H2S: Implications in hypertension

Nitric oxide (NO) and hydrogen sulfide (H2S) are two gasotransmitters that are produced in the vasculature and contribute to the regulation of vascular tone. NO and H2S are synthesized in both vascular smooth muscle and endothelial cells; NO functions primarily through the sGC/cGMP pathway, and H2S mainly through activation of the ATP-dependent potassium channels; both leading to relaxation of vascular smooth muscle cells. A deficit in the NO/H2S homeostasis is involved in the pathogenesis of various cardiovascular diseases, especially hypertension. It is now becoming increasingly clear that there are important interactions between NO and H2S and that have a profound impact on vascular tone and this may provide insights into the new therapeutic interventions. The aim of this review is to provide a better understanding of individual and interactive roles of NO and H2S in vascular biology. Overall, available data indicate that both NO and H2S contribute to vascular (patho)physiology and in regulating blood pressure. In addition, boosting NO and H2S using various dietary sources or donors could be a hopeful therapeutic strategy in the management of hypertension.

Therapeutic potential of omega-3 fatty acid-derived epoxyeicosanoids in cardiovascular and inflammatory diseases

Numerous benefits have been attributed to dietary long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs), including protection against cardiac arrhythmia, triglyceride-lowering, amelioration of inflammatory, and neurodegenerative disorders. This review covers recent findings indicating that a variety of these beneficial effects are mediated by "omega-3 epoxyeicosanoids", a class of novel n-3 LC-PUFA-derived lipid mediators, which are generated via the cytochrome P450 (CYP) epoxygenase pathway. CYP enzymes, previously identified as arachidonic acid (20:4n-6; AA) epoxygenases, accept eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA), the major fish oil n-3 LC-PUFAs, as efficient alternative substrates. In humans and rodents, dietary EPA/DHA supplementation causes a profound shift of the endogenous CYP-eicosanoid profile from AA- to EPA- and DHA-derived metabolites, increasing, in particular, the plasma and tissue levels of 17,18-epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic acid (19,20-EDP). Based on preclinical studies, these omega-3 epoxyeicosanoids display cardioprotective, vasodilatory, anti-inflammatory, and anti-allergic properties that contribute to the beneficial effects of n-3 LC-PUFAs in diverse disease conditions ranging from cardiac disease, bronchial disorders, and intraocular neovascularization, to allergic intestinal inflammation and inflammatory pain. Increasing evidence also suggests that background nutrition as well as genetic and disease state-related factors could limit the response to EPA/DHA-supplementation by reducing the formation and/or enhancing the degradation of omega-3 epoxyeicosanoids. Recently, metabolically robust synthetic analogs mimicking the biological activities of 17,18-EEQ have been developed. These drug candidates may overcome limitations of dietary EPA/DHA supplementation and provide novel options for the treatment of cardiovascular and inflammatory diseases.

Bilayered Nanoparticles with Sequential Release of VEGF Gene and Paclitaxel for Restenosis Inhibition in Atherosclerosis

Complete reendothelialization followed by inhibition of smooth muscle cell (SMC) proliferation is considered as an effective therapeutic option to prevent restenosis. We have designed poly(lactide-co-glycolide)-loaded bilayered nanoparticles (NPs) with the ability to sequentially release vascular endothelial growth factor (VEGF)-encoding plasmids from the outer layer and paclitaxel (PTX) from the core to promote endothelial regeneration as well as prevent restenosis. Comparing with conventional NPs, which release VEGF plasmid and PTX simultaneously, we expect that the bilayered NPs could release the VEGF plasmid more rapidly, followed by a delayed release of PTX, resulting in an efficient VEGF gene transfection, which ideally could promote reendothelialization and inhibit excessive SMC growth. Indeed, in the present study, we have observed efficient gene transfection using a model plasmid as well as cell growth attenuation in vitro using Chinese hamster ovary cells. Therapeutic efficacy of the bilayered NPs on restenosis was further evaluated in vivo using a rabbit model of atherosclerosis. The bilayered NPs were administered locally via balloon angioplasty to the injured aortic wall through perfusion. Twenty-eight days after the NP administration, rabbits treated with the bilayered NPs exhibited rapid reendothelialization and inhibition of restenosis, as demonstrated by histological analysis. Increased level of VEGF and decreased level of C-reactive protein, a biological marker that is closely related to atherosclerosis, were also observed from animals treated with the bilayered NPs, implicating ameliorated atherosclerosis. Our results suggest that the VEGF plasmid-/PTX-loaded bilayered NPs exert a beneficial impact on atherosclerotic restenosis by sequentially releasing VEGF and PTX in vivo.