Vascular endothelium and inflammatory process, in patients with combined Type 2 diabetes mellitus and coronary atherosclerosis: the effects of vitamin C

Insight into increased risk of portal vein thrombosis in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the leading chronic liver diseases with increased morbidity and mortality rates for extrahepatic diseases (including cardiovascular disease, portal vein thrombosis, etc.). There is an increased risk of thrombosis in both the portal and systemic circulation in patients with NAFLD, independent of traditional liver cirrhosis. However, increased portal pressure, the most critical factor, is frequently observed in NAFLD patients, predisposing them to portal vein thrombosis (PVT). It has been reported that there is an 8.5% incidence of PVT among patients with non-cirrhotic NAFLD in a prospective cohort study. Based on the prothrombotic status of NAFLD itself, patients combined with cirrhosis may accelerate the development of PVT and lead to a poor prognosis. Moreover, PVT has been shown to complicate the procedure and adversely affect the outcome during liver transplantation surgery. NAFLD is in a prothrombotic state, and its underlying mechanisms have not been fully understood so far. Particularly noteworthy is that gastroenterologists currently overlook the higher risk of PVT in NAFLD. We investigate the pathogenesis of NAFLD complicated with PVT from the perspective of primary, secondary, and tertiary hemostasis, and also summarize relevant studies in humans. Some treatment options that may affect NAFLD and its PVT are also explored to improve patient-oriented outcomes.

Nutrients and Dietary Approaches in Patients with Type 2 Diabetes Mellitus and Cardiovascular Disease: A Narrative Review

Cardiovascular disease (CVD) is the most common cause of morbidity and mortality in developed countries. The prevalence of CVD is much higher in patients with type 2 diabetes mellitus (T2DM), who may benefit from lifestyle changes, which include adapted diets. In this review, we provide the role of different groups of nutrients in patients with T2DM and CVD, as well as dietary approaches that have been associated with better and worse outcomes in those patients. Many different diets and supplements have proved to be beneficial in T2DM and CVD, but further studies, guidelines, and dietary recommendations are particularly required for patients with both diseases.

Does Evidence Exist to Blunt Inflammatory Response by Nutraceutical Supplementation during COVID-19 Pandemic? An Overview of Systematic Reviews of Vitamin D, Vitamin C, Melatonin, and Zinc

More than one year has passed since the first cases of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome (SARS)-CoV-2 coronavirus were reported in Wuhan (China), rapidly evolving into a global pandemic. This infectious disease has become a major public health challenge in the world. Unfortunately, to date, no specific antivirals have been proven to be effective against COVID-19, and although a few vaccines are available, the mortality rate is not decreasing but is still increasing. One therapeutic strategy has been focused on infection prevention and control measures. In this regard, the use of nutraceutical supports may play a role against some aspect of the infection, particularly the inflammatory state and the immune system function of patients, thus representing a strategy to control the worst outcomes of this pandemic. For this reason, we performed an overview including meta-analyses and systematic reviews to assess the association among melatonin, vitamin C, vitamin D, zinc supplementation and inflammatory markers using three databases, namely, MEDLINE, PubMed Central and the Cochrane Library of Systematic Reviews. According to the evidence available, an intake of 50,000 IU/month of vitamin D showed efficacy in CRP. An amount of 1 to 2 g per day of vitamin C demonstrated efficacy both in CRP and endothelial function, and a dosage of melatonin ranging from 5 to 25 mg /day showed good evidence of efficacy in CRP, TNF and IL6. A dose of 50 mg/day of elemental zinc supplementation showed positive results in CRP. Based on the data reported in this review, the public health system could consider whether it is possible to supplement the current limited preventive measures through targeted nutraceutical large-scale administration.

Peripheral Artery Disease in Diabetes Mellitus: Focus on Novel Treatment Options

Diabetes mellitus (DM) and peripheral artery disease (PAD) are two clinical entities closely associated. They share many pathophysiological pathways such as inflammation, endothelial dysfunction, oxidative stress and pro-coagulative unbalance. Emerging data focusing on agents targeting these pathways may be promising. Moreover, due to the increased cardiovascular risk, there is a growing interest in cardiovascular and "pleiotropic" effects of novel glucose lowering drugs. This review summarizes the main clinical features of PAD in patients, the diagnostic process and current medical/interventional approaches, ranging from "classical treatment" to novel agents.

Antioxidant and Oxidative Stress: A Mutual Interplay in Age-Related Diseases

Aging is the progressive loss of organ and tissue function over time. Growing older is positively linked to cognitive and biological degeneration such as physical frailty, psychological impairment, and cognitive decline. Oxidative stress is considered as an imbalance between pro- and antioxidant species, which results in molecular and cellular damage. Oxidative stress plays a crucial role in the development of age-related diseases. Emerging research evidence has suggested that antioxidant can control the autoxidation by interrupting the propagation of free radicals or by inhibiting the formation of free radicals and subsequently reduce oxidative stress, improve immune function, and increase healthy longevity. Indeed, oxidation damage is highly dependent on the inherited or acquired defects in enzymes involved in the redox-mediated signaling pathways. Therefore, the role of molecules with antioxidant activity that promote healthy aging and counteract oxidative stress is worth to discuss further. Of particular interest in this article, we highlighted the molecular mechanisms of antioxidants involved in the prevention of age-related diseases. Taken together, a better understanding of the role of antioxidants involved in redox modulation of inflammation would provide a useful approach for potential interventions, and subsequently promoting healthy longevity.

Sympathoexcitation constrains vasodilation in the human skeletal muscle microvasculature during postocclusive reactive hyperemia

We used diffuse correlation spectroscopy to investigate sympathetic vasoconstriction, local vasodilation, and integration of these two responses in the skeletal muscle microvasculature of 20 healthy volunteers. Diffuse correlation spectroscopy probes were placed on the flexor carpi radialis muscle or vastus lateralis muscle, and a blood flow index was derived continuously. We measured hemodynamic responses during sympathoexcitation induced by forehead cooling, after which the effects of the increased sympathetic tone on vasodilatory responses during postocclusive reactive hyperemia (PORH) were examined. PORH was induced by releasing arterial occlusion (3 min) in an arm or leg. To increase sympathetic tone during PORH, forehead cooling was begun 60 s before the occlusion release and ended 60 s after the release. During forehead cooling, mean arterial pressure rose significantly and was sustained at an elevated level. Significant vasoconstriction and decreases in blood flow index followed by gradual blunting of the vasoconstriction also occurred. The time course of these responses is in good agreement with previous observations in animals. The acute sympathoexcitation diminished the peak vasodilation during PORH only in the vastus lateralis muscle, but it hastened the decline in vasodilation after the peak in both the flexor carpi radialis muscle and vastus lateralis muscle. Consequently, the total vasodilatory response assessed as the area of the vascular conductance during the first minute of PORH was significantly diminished in both regions. We conclude that, in humans, the integrated effects of sympathetic vasoconstriction and local vasodilation have an important role in vascular regulation and control of perfusion in the skeletal muscle microcirculation.

NEW & NOTEWORTHY We used diffuse correlation spectroscopy to demonstrate that acute sympathoexcitation constrains local vasodilation in the human skeletal muscle microvasculature during postocclusive reactive hyperemia. This finding indicates that integration of sympathetic vasoconstriction and local vasodilation is importantly involved in vascular regulation and the control of perfusion of the skeletal muscle microcirculation in humans.

Antioxidant effects of vitamins in type 2 diabetes: a meta-analysis of randomized controlled trials

BACKGROUND

Vitamins are essential micronutrients with antioxidant potential that may provide a complementary treatment for patients with chronic diseases. Our aim was to assess the effect of vitamin supplementation on the antioxidant status and glycemic index of type 2 diabetes mellitus patients.

METHODS

We performed a systematic review with meta-analyses. Electronic searches were conducted in PubMed, Scopus, and Web of Science (December 2017). Randomized controlled trials evaluating the effect of any vitamin or vitamin complex supplementation on antioxidant status as primary outcome were included. The outcomes considered were: reduction of malondialdehyde (MDA); augmentation of glutathione peroxidase (GPx); changes in total antioxidant capacity (TAC), enhance in superoxide dismutase enzyme-SOD, and thiobarbituric acid reactive substances (TBARS). Outcomes of glycemic control were also evaluated. Pairwise meta-analyses were performed using software Review Manager 5.3.

RESULTS

Thirty trials fulfilled the inclusion criteria, but only 12 could be included in the meta-analyses of antioxidant outcomes. The most commonly studied vitamins were B, C, D and E. Vitamin E was related to significant reduction of blood glucose as well as glycated hemoglobin compared to placebo, while both vitamins C and E were mainly associated with reducing MDA and TBARS and elevating GPx, SOD and TAC, compared to placebo. However, outcome reports in this field are still inconsistent (e.g. because of a lack of standard measures).

CONCLUSIONS

Supplementation of vitamin E may be a valuable strategy for controlling diabetes complications and enhancing antioxidant capacity. The effects of other micronutrients should be further investigated in larger and well-designed trials to properly place these complementary therapies in clinical practice.

Targeting endothelial metaflammation to counteract diabesity cardiovascular risk: Current and perspective therapeutic options

The association of obesity and diabetes, termed "diabesity", defines a combination of primarily metabolic disorders with insulin resistance as the underlying common pathophysiology. Cardiovascular disorders associated with diabesity represent the leading cause of morbidity and mortality in the Western world. This makes diabesity, with its rising impacts on both health and economics, one of the most challenging biomedical and social threats of present century. The emerging comprehension of the genes whose alteration confers inter-individual differences on risk factors for diabetes or obesity, together with the potential role of genetically determined variants on mechanisms controlling responsiveness, effectiveness and safety of anti-diabetic therapy underlines the need of additional knowledge on molecular mechanisms involved in the pathophysiology of diabesity. Endothelial cell dysfunction, resulting from the unbalanced production of endothelial-derived vascular mediators, is known to be present at the earliest stages of insulin resistance and obesity, and may precede the clinical diagnosis of diabetes by several years. Once considered as a mere consequence of metabolic abnormalities, it is now clear that endothelial dysfunctional activity may play a pivotal role in the progression of diabesity. In the vicious circle where vascular defects and metabolic disturbances worsen and reinforce each other, a low-grade, chronic, and 'cold' inflammation (metaflammation) has been suggested to serve as the pathophysiological link that binds endothelial and metabolic dysfunctions. In this paradigm, it is important to consider how traditional antidiabetic treatments (specifically addressing metabolic dysregulation) may directly impact on inflammatory processes or cardiovascular function. Indeed, not all drugs currently available to treat diabetes possess the same anti-inflammatory potential, or target endothelial cell function equally. Perspective strategies pointing at reducing metaflammation or directly addressing endothelial dysfunction may disclose beneficial consequences on metabolic regulation. This review focuses on existing and potential new approaches ameliorating endothelial dysfunction and vascular inflammation in the context of diabesity.

Antioxidant Supplementation in the Treatment of Aging-Associated Diseases

Oxidative stress is generally considered as the consequence of an imbalance between pro- and antioxidants species, which often results into indiscriminate and global damage at the organismal level. Elderly people are more susceptible to oxidative stress and this depends, almost in part, from a decreased performance of their endogenous antioxidant system. As many studies reported an inverse correlation between systemic levels of antioxidants and several diseases, primarily cardiovascular diseases, but also diabetes and neurological disorders, antioxidant supplementation has been foreseen as an effective preventive and therapeutic intervention for aging-associated pathologies. However, the expectations of this therapeutic approach have often been partially disappointed by clinical trials. The interplay of both endogenous and exogenous antioxidants with the systemic redox system is very complex and represents an issue that is still under debate. In this review a selection of recent clinical studies concerning antioxidants supplementation and the evaluation of their influence in aging-related diseases is analyzed. The controversial outcomes of antioxidants supplementation therapies, which might partially depend from an underestimation of the patient specific metabolic demand and genetic background, are presented.

Modulation of Cytokines in Cancer Patients by Intravenous Ascorbate Therapy

BACKGROUND

Cytokines play an important role in tumor angiogenesis and inflammation. There is evidence in the literature that high doses of ascorbate can reduce inflammatory cytokine levels in cancer patients. The objective of this study was to investigate the effect of treatment by intravenous vitamin C (IVC) on cytokines and tumor markers.

MATERIAL/METHODS

With the availability of protein array kits allowing assessment of many cytokines in a single sample, we measured 174 cytokines and additional 54 proteins and tumor markers in 12 cancer patients before and after a series of IVC treatments.

RESULTS

Presented results show for our 12 patients the effect of treatment resulted in normalization of many cytokine levels. Cytokines that were most consistently elevated prior to treatments included M-CSF-R, Leptin, EGF, FGF-6, TNF-α, β, TARC, MCP-1,4, MIP, IL-4, 10, IL-4, and TGF-β. Cytokine levels tended to decrease during the course of treatment. These include mitogens (EGF, Fit-3 ligand, HGF, IGF-1, IL-21R) and chemo-attractants (CTAC, Eotaxin, E-selectin, Lymphotactin, MIP-1, MCP-1, TARC, SDF-1), as well as inflammation and angiogenesis factors (FGF-6, IL-1β, TGF-1).

CONCLUSIONS

We are able to show that average z-scores for several inflammatory and angiogenesis promoting cytokines are positive, indicating that they are higher than averages for healthy controls, and that their levels decreased over the course of treatment. In addition, serum concentrations of tumor markers decreased during the time period of IVC treatment and there were reductions in cMyc and Ras, 2 proteins implicated in being upregulated in cancer.

Endothelial immunomediated reactivity in acute cardiac ischaemia: Role of endothelin 1, interleukin 8 and NT-proBNP in patients affected by unstable angina pectoris

The role of endothelium in the progression of atheromasic disease has already been demonstrated. Endothelin-1 (ET-1) is released from endothelial cells during acute and chronic vascular damage and it appears to be the strongest vasoconstrictor agent known.The aim of this study is to investigate the amount of endothelial damage in patients with unstable angina (UA), as defined by serum levels of ET-1, to verify a possible correlation with increased ischaemic damage by evaluation of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) and interleukin 8 (IL-8) levels.Serum levels of ET-1, IL-8 and NT-proBNP obtained from 10 patients affected by low-risk UA were compared to those belonging to eight healthy subjects. In order to compare the laboratory data pertaining to the two populations, a Student's t-test and a Mann-Whitney U test were performed.Levels of ET-1, IL-8 and NT-proBNP in samples of peripheral blood of patients affected by UA were significantly elevated, compared with those of the control group. The linear correlation analysis demonstrated a positive and significant correlation between levels of ET-1 and IL-8, between levels of ET-1 and NT-proBNP, and between levels of IL-8 and NT-proBNP in subjects affected by UA.Early elevated levels of ET-1, IL-8 and NT-proBNP in patients with UA show a coexistence between ischaemic insults and endothelial damages. A positive and significant linear correlation between levels of ET-1 and IL-8, between levels of ET-1 and NT-proBNP, and between levels of IL-8 and NT-proBNP confirms that an increased ischaemic insult is correlated to inflammation signs and endothelium damage signs.In patients with UA, ischaemia is always associated with a systemic immuno-mediated activity induced by acute endothelial damage. We suggest early administration of ET-1-selective receptor blockers and anti-inflammatory drugs.

Effect of vitamin C on endothelial function in health and disease: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Observational studies indicate that higher vitamin C intake is associated with reduced risk for cardiovascular diseases. However, randomised controlled trials (RCT) examining the effect of vitamin C on endothelial function (EF) have reported inconsistent results. The aims of this systematic review and meta-analysis were to determine the effect of vitamin C supplementation on EF and to investigate whether the effect was influenced by health status, study duration, dose and route of vitamin C administration.

METHODS

We searched the Medline, Embase, Cochrane Library, and Scopus databases from inception to May 2013 for studies that met the following criteria: 1) RCT with adult participants, 2) vitamin C administered alone, 3) studies that quantified EF using commonly applied methods including ultrasound, plethysmography and pulse wave analysis.

RESULTS

Pooling the data from 44 clinical trials showed a significant positive effect of vitamin C on EF (SMD: 0.50, 95% CI: 0.34, 0.66, P < 0.001). Stratification of the analysis by health outcome revealed improved EF in atherosclerotic (SMD: 0.84, 95% CI: 0.41, 1.26, P < 0.001), diabetic (SMD: 0.52, 95% CI: 0.21, 0.82, P < 0.001) and heart failure patients (SMD: 0.48, 95% CI: 0.08, 0.88, P < 0.02) after vitamin C supplementation. The effect size appeared to be unaffected by study design, duration, baseline plasma vitamin C concentration or route of administration of vitamin C. The meta-regression showed a significant positive association between vitamin C dose and improvement in EF (β: 0.00011, 95% CI: 0.00001, 0.00021, P = 0.03).

CONCLUSIONS

Vitamin C supplementation improved EF. The effect of vitamin C supplementation appeared to be dependent on health status, with stronger effects in those at higher cardiovascular disease risk. PROSPERO Database registration: CRD42013004567, http://www.crd.york.ac.uk/prospero/

Effect of antioxidant vitamin supplementation on endothelial function in type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

Controversy exists among trials assessing whether prolonged antioxidant vitamin supplementation improves endothelial function in type 2 diabetes mellitus (T2DM) subjects. The aim of this study was to systematically review and quantify the effect of antioxidant vitamin supplementation on endothelial function in T2DM subjects. MEDLINE, Cochrane, Scopus and Web of Science were searched up to February 2013 for randomized controlled trials assessing the effect of antioxidant vitamin E and/or C supplementation on endothelial function in T2DM subjects. Ten randomized controlled trials comparing antioxidant vitamin-supplemented and control groups (overall n = 296) met the inclusion criteria. Post-intervention standardized mean difference (SMD) in endothelial function did not reach statistical significance between groups (0.35; 95% confidence interval = -0.17, 0.88; P = 0.18). In subgroup analysis, post-intervention endothelial function was significantly improved by antioxidant vitamin supplementation in T2DM subgroups with body mass index (BMI) ≤ 29.45 kg m(-2) (SMD = 1.02; P < 0.05), but not in T2DM subgroups with BMI > 29.45 kg m(-2) (SMD = -0.07; P = 0.70). In meta-regression, an inverse association was found between BMI and post-intervention SMD in endothelial function (B = -0.024, P = 0.02). Prolonged antioxidant vitamin E and/or C supplementation could be effective to improve endothelial function in non-obese T2DM subjects.

Protective effect of anti-oxidants on endothelial function in young Korean-Asians compared to Caucasians

Background

Previous studies show that Asians have an impaired blood flow response (BFR) to occlusion after a single high fat (HF) meal. The mechanism is believed to be the presence and susceptibility to high free radicals in their blood. The free radical concentration after a HF meal has not been examined in Asians. Further the BFR to heat after a single HF meal in Koreans has not been measured.

Material/Methods

This study evaluated postprandial endothelial function by measuring the BFR to vascular occlusion and local heat before and after a HF meal and the interventional effects of anti-oxidant vitamins on improving endothelial function in young Korean-Asians (K) compared to Caucasians (C) with these assessments. Ten C and ten K participated in the study (mean age 25.3±3.6 years old). BFR to vascular occlusion and local heat and oxidative stress were assessed after a single low fat (LF) and HF meal at 2 hours compared to baseline. After administration of vitamins (1000 mg of vitamin C, 800 IU of vitamin E, and 300 mg of Coenzyme Q-10) for 14 days, the same measurements were made.

Results

This study showed that the skin BFR to vascular occlusion and local heat following a HF meal significantly decreased and free radicals significantly increased at 2 hours compared to baseline in K (p<.001), but not in C. When vitamins were given, the BFR to vascular occlusion and local heat before and after HF meal were not significantly different in K and C.

Conclusions

These findings suggest that even a single HF meal can reduce endothelial response to stress through an oxidative stress mechanism but can be blocked by antioxidants, probably through scavenging free radicals in K. Since endothelial function improved even before a HF meal in K, endothelial damage from an Americanized diet may be reduced in K by antioxidants.

Authors' perspective: What is the optimum intake of vitamin C in humans?

The recommended dietary allowance (RDA) of vitamin C has traditionally been based on the prevention of the vitamin C deficiency disease, scurvy. While higher intakes of vitamin C may exert additional health benefits, the limited Phase III randomized placebo-controlled trials (RCTs) of vitamin C supplementation have not found consistent benefit with respect to chronic disease prevention. To date, this has precluded upward adjustments of the current RDA. Here we argue that Phase III RCTs-designed principally to test the safety and efficacy of pharmaceutical drugs-are ill suited to assess the health benefits of essential nutrients; and the currently available scientific evidence is sufficient to determine the optimum intake of vitamin C in humans. This evidence establishes biological plausibility and mechanisms of action for vitamin C in the primary prevention of coronary heart disease, stroke, and cancer; and is buttressed by consistent data from prospective cohort studies based on blood analysis or dietary intake and well-designed Phase II RCTs. These RCTs show that vitamin C supplementation lowers hypertension, endothelial dysfunction, chronic inflammation, and Helicobacter pylori infection, which are independent risk factors of cardiovascular diseases and certain cancers. Furthermore, vitamin C acts as a biological antioxidant that can lower elevated levels of oxidative stress, which also may contribute to chronic disease prevention. Based on the combined evidence from human metabolic, pharmacokinetic, and observational studies and Phase II RCTs, we conclude that 200 mg per day is the optimum dietary intake of vitamin C for the majority of the adult population to maximize the vitamin's potential health benefits with the least risk of inadequacy or adverse health effects.

Myocardial therapeutic angiogenesis: a review of the state of development and future obstacles

A significant percentage of patients have coronary artery disease that is too advanced or diffuse for percutaneous or surgical intervention. Therapeutic angiogenesis is a treatment modality to induce vessel formation that is being developed for patients with advanced coronary disease not amenable to currently available interventions. A number of approaches to induce coronary collateralization are being developed. These include gene, protein, cellular and miRNA modalities, each of which have advantages and disadvantages. At this time, no modality has emerged as the single clear choice, and combination therapies may provide synergistic benefits. However, there have been a number of recent studies advancing our knowledge as to how we can refine procollateralizing treatments. In this article, we will examine some recent successes and future obstacles in the effort to bring therapeutic angiogenesis to patients.

Coenzyme Q(10) , endothelial function, and cardiovascular disease

Since the time a precise role of coenzyme Q(10) (CoQ(10) ) in myocardial bioenergetics was established, the involvement of CoQ in the pathophysiology of heart failure was hypothesized. This provided the rationale for numerous clinical trials of CoQ(10) as adjunctive treatment for heart failure. A mild hypotensive effect of CoQ was reported in the early years of clinical use of this compound. We review early human and animal studies on the vascular effects of CoQ. We then focus on endothelial dysfunction in type 2 diabetes and the possible impact on this condition of antioxidants and nutritional supplements, and in particular the therapeutic effects of CoQ. The effect of CoQ(10) on endothelial dysfunction in ischemic heart disease is also reviewed together with recent data highlighting that treatment with CoQ(10) increases extracellular SOD activity.

Vitamin C status is related to proinflammatory responses and impaired vascular endothelial function in healthy, college-aged lean and obese men

Vitamin C supplementation has been suggested to reduce cardiovascular disease risk. However, no studies have examined the relationship between vitamin C status and vascular dysfunction in lean and obese individuals in the absence of supplementation. We examined whether vascular function is interrelated with vitamin C status and inflammation in healthy, college-aged lean and obese men with no history of dietary supplementation. A cross-sectional study was conducted during winter 2008 in lean and obese men aged 21±3 years (n=8/group). Brachial artery flow-mediated dilation (FMD) was measured to determine vascular endothelial function. Plasma antioxidants (vitamin C, vitamin E, and thiols), inflammatory proteins (C-reactive protein [CRP], myeloperoxidase [MPO], and cytokines), and cellular adhesion molecules were measured. Participants also completed 3-day food records on the days preceding their vascular testing. Group differences were evaluated by t tests, and correlation coefficients were determined by linear regression. FMD was 21% lower (P<0.05) in obese men. They also had 51% lower vitamin C intakes and 38% lower plasma vitamin C concentrations. Obese men had greater plasma concentrations of CRP, MPO, inflammatory cytokines, and cellular adhesion molecules. Participants' CRP and MPO were each inversely related (P<0.05) to FMD (r=-0.528 and -0.625) and plasma vitamin C (r=-0.646 and -0.701). These data suggest that low vitamin C status is associated with proinflammatory responses and impaired vascular function in lean and obese men. Additional study is warranted to determine whether improving dietary vitamin C intakes from food attenuate vascular dysfunction.

Association of sarcoidosis with endothelial function, arterial wall properties, and biomarkers of inflammation

BACKGROUND

Sarcoidosis is an inflammatory disease, which may affect vascular function. The study was designed to assess the impact of sarcoidosis on endothelial function and arterial stiffness.

METHODS

Eighty-seven sarcoidosis patients and eighty-seven matched healthy subjects (Cl) were included in the study. Sarcoidosis patients were divided into two groups. Group 1 included patients never treated and group 2 included patients receiving cortisone treatment. Endothelial function was evaluated by flow-mediated dilatation (FMD). Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness and augmentation index (AI75) as a measure of arterial wave reflections. Serum levels of soluble intercellular adhesion molecule-1 and tumor necrosis factor-α (TNF-α), were measured.

RESULTS

In the totality of the population, sarcoidosis patients had significantly lower FMD (P < 0.01) and significantly higher AI75 (P < 0.05). There was also a significant difference, between group 1, and Cl in FMD and AI75, but there was no difference between group 2 and Cl in FMD and AI75. AI75 values were significantly correlated with serum levels of intercellular adhesion molecule-1 (ICAM-1) (r = 0.370, P < 0.01) and TNF-α (r = 0.219, P = 0.049).

CONCLUSIONS

In the present study, we have shown that sarcoidosis patients have impaired endothelial function and increased arterial stiffness. Sarcoidosis patients on cortisone treatment had no differences compared to controls on the vascular parameters. Moreover, there was a significant correlation between inflammatory process and vascular function impairment. These findings indicate that sarcoidosis patients have impaired vascular function and increased inflammatory status, which may improve with cortisone treatment.

Grape seed extract ameliorates tumor necrosis factor-α-induced inflammatory status of human umbilical vein endothelial cells

BACKGROUND

Inflammation has played a key role in the causation of atherosclerosis. However, the effects of grape seed extract (GSE) on the pro-inflammatory intracellular signaling, enzyme activity, and inflammatory mediators of endothelial cells have not been sufficiently studied, and less information exists on the comparison between GSE and vitamin C, a well-known antioxidant compound, on their anti-inflammatory properties.

PURPOSE

We investigated the effects of GSE and vitamin C on the cell viability, oxidative stress, monocyte adhesion, the expression of nuclear factor-κB inhibitor (IκB), intercellular adhesion molecule-1 (ICAM-1) and cyclooxygenase-2 (COX-2), and the production of prostaglandin E(2) (PG E(2)) in TNF-α-treated human umbilical vein endothelial cells (HUVECs).

METHODS

Cell viability was measured by MTT assay. The adhesion of THP-1 to HUVECs was evaluated by cell adhesion assay. The oxidized nucleoside 8-hydroxydeoxyguanosine (8-OHdG) (an indicator of oxidative damage to DNA), ICAM-1, and PG E(2) were measured by ELISA. IκB and COX-2 expression were evaluated by western blot analysis.

RESULTS

TNF-α (10, 20, and 50 ng/mL), GSE (50 and 200 μg/mL), or vitamin C (100 μM) did not affect cell viability. GSE (50-100 μg/mL) attenuated TNF-α (20 ng/mL)-induced 8-OHdG production, THP-1 adhesion, the expression of IκB degradation, ICAM-1 and COX-2, and the production of PGE(2) in a dose-dependent manner. Vitamin C (100 μM) also showed significant antioxidative and anti-inflammatory effects.

CONCLUSIONS

GSE effectively ameliorates TNF-α-induced inflammatory status of HUVECs. The findings of the present study suggest that consumption of GSE may be beneficial to inflammatory atherosclerosis.

Endothelial function in individuals with coronary artery disease with and without type 2 diabetes mellitus

The goal of this study was to determine if individuals with coronary artery disease (CAD) and type 2 diabetes mellitus (T2DM) had greater endothelial dysfunction (ED) than individuals with only CAD. Flow-mediated dilation (FMD), calculated as percentage increase in brachial artery diameter in response to postischemic blood flow, was measured after an overnight fast in 2 cohorts. The first cohort included 76 participants in the Northern Manhattan Study with CAD; 25 also had T2DM. The second cohort was composed of 27 individuals with both T2DM and CAD who were participants in a study of postprandial lipemia. Combined, we analyzed 103 patients with CAD: 52 with T2DM (T2DM+) and 51 without T2DM (T2DM-). The 52 CAD T2DM+ subjects had a mean FMD of 3.9% +/- 3.2%, whereas the 51 CAD T2DM- subjects had a greater mean FMD of 5.5% +/- 4.0% (P < .03). An investigation of various confounders known to affect FMD identified age and body mass index as the only significant covariates in a multiple regression model. Adjusting for age and body mass index, we found that FMD remained lower in T2DM+ subjects compared with T2DM- subjects (difference, -1.99%; P < .03). In patients with CAD, the concomitant presence of T2DM is independently associated with greater ED, as measured by FMD. This finding may be relevant to the greater early and late morbidity and mortality observed in patients with both CAD and T2DM.

Combined effects of atorvastatin and metformin on glucose-induced variations of inflammatory process in patients with diabetes mellitus

BACKGROUND

Statin treatment improves survival in patients with atherosclerosis, but their effect on the glucose-induced variations of inflammatory markers, is unknown. We examined the effect of combined therapy with atorvastatin and metformin on glucose-induced variations of inflammatory molecules in patients with newly diagnosed diabetes mellitus type 2 (DM).

METHODS

Thirty five subjects with newly diagnosed DM were randomized to receive metformin 850 mg/d (M, n=17) or metformin 850 mg/d+atorvastatin 10mg (n=18). All subjects underwent glucose loading (75 g oral glucose) at baseline and after 12 weeks of treatment. Blood samples were obtained at baseline and 3h post-loading, while serum tumor necrosis factor alpha (TNF-α) levels were determined at baseline and at 3h.

RESULTS

Serum TNF-α remained unchanged in metformin at baseline (1.36±0.18 to 1.47±0.21 pg/ml p=NS) and after treatment (1.44±0.71 to 1.31±0.17 pg/ml, p=NS), while it was reduced in metformin+atorvastatin (2.3±0.3 to 2.0±0.4 pg/ml, p=NS at baseline and 1.80±0.2 to 1.65±0.2 pg/ml, p=0.03 after treatment).

CONCLUSIONS

Interestingly, the combination of metformin and atorvastatin partly prevents the glucose-loading induced elevation of glucose levels (at 1 h), suggesting a better response to glucose intake than monotherapy with metformin. In addition, combined treatment with atorvastatin and metformin reduces the post-glucose loading levels of TNF-α compared to metformin monotherapy.

Role of marginal vitamin C deficiency in atherogenesis: in vivo models and clinical studies

Vitamin C is a pivotal redox modulater in many biological reactions of which several remain poorly understood. Naturally, vitamin C has been the subject of many investigations over the past decades in relation to its possible beneficial effects on cardiovascular disease primarily based on its powerful yet general antioxidant properties. However, growing epidemiological, clinical and experimental evidence now suggests a more specific role of ascorbate in vasomotion and in the prevention of atherosclerosis. For example, in contrast to most other biological antioxidants, administration of vitamin C can apparently induce vasodilation. Millions of people worldwide can be diagnosed with vitamin C deficiency according to accepted definitions. In this perspective, the present review examines the evidence for a specific link between vitamin C deficiency and increased risk of atherosclerosis as well as the possible mechanisms by which vitamin C may exert its protective function.

Repeatability of a dual gradient-recalled echo MRI method for monitoring post-isometric contraction blood volume and oxygenation changes

The purpose of this study was to assess the repeatability of a dual gradient-recalled echo (GRE) muscle functional MRI technique. On 2 days, subjects (n = 8) performed 10 s isometric dorsiflexion contractions under conditions of: (1) maximal voluntary contraction (MVC), (2) 50% MVC (50% MVC), or (3) 50% MVC with concurrent proximal arterial cuff occlusion (50% MVC(cuff)). Functional MRI data were acquired using single-slice dual GRE (TR/TE = 1000/6, 46 ms)-echo planar imaging for 20 s before, during, and for 180 s after each contraction. The mean signal intensity (SI) time courses at each TE (SI(6) and SI(46), reflecting variations in blood volume and %HbO(2), respectively) from the tibialis anterior (TA) and extensor digitorum longus (EDL) muscles were characterized with the post-contraction change in SI and the time-to-peak SI (DeltaSI and TTP, respectively). DeltaSI(6) following an MVC was 36% higher than that obtained after a 50% MVC (p = 0.048). For DeltaSI(6), the highest intraclass correlation coefficients (ICCs) were observed for the TA muscle in the 50% MVC and MVC conditions, with values of 0.83 (p = 0.01) and 0.88 (p = 0.005), respectively. Bland-Altman plots revealed repeatability coefficients (RCs) for the 50% MVC and MVC conditions in the TA muscle of 1.9 and 1.4, respectively. The most repeatable measures for DeltaSI(46) were obtained for the 50% MVC and MVC conditions in the EDL muscle (p = 0.01 and p = 0.04, respectively). Bland-Altman plots revealed RC's for 50% MVC and MVC conditions in the EDL muscle of 3.9 and 5.7, respectively. DeltaSI(6) and DeltaSI(46) increased as a function of the contraction intensity. The repeatability of the method depends on the muscle and contraction condition being evaluated, and in general, is higher following an MVC.

Effects of insulin resistance on endothelial function: possible mechanisms and clinical implications

Insulin resistance (IR) is defined as a reduced responsiveness of peripheral tissues to the effects of the hormone, referring to abated ability of insulin in stimulating glucose uptake in peripheral tissues and in inhibiting hepatic glucose output. Insulin has both a vasodilatory effect, which is largely endothelium dependent through the release of nitric oxide, and a vasoconstrictory effect through the stimulation of the sympathetic nervous system and the release of endothelin-1. IR and endothelial dysfunction (ED) are not only linked by common pathogenetic mechanisms, involving deranged insulin signalling pathways, but also by other, indirect to the hormone's actions, mechanisms. Different treatment modalities have been proposed to affect positively both the metabolic effects of insulin and ED. Weight loss has been shown to improve sensitivity to insulin as a result of either altered diet or exercise. Exercise has favourable effects on endothelial function in normal states and in states of disease, in men and women, and throughout the age spectrum and, hence, in IR states. Metformin improves sensitivity to insulin and most likely affects positively ED. Studies have shown that inhibitors of the renin-angiotensin system alter IR favourably, while Angiotensin converting enzyme (ACE) inhibitors and Angiotensin receptor type II (ATII) inhibitors improve ED. Ongoing studies are expected to shed more light on the issue of whether treatment with the thiazolidinediones results in improvement of endothelial function, along with the accepted function of improving insulin sensitivity. Finally, improved endothelial function by such treatments is not in itself proof of reduced risk for atherosclerosis; this remains to be directly tested in clinical trials.

The markers of inflammation and endothelial dysfunction in correlation with glycated haemoglobin are present in type 2 diabetes mellitus patients but not in their relatives

The aim of this study is to test several biomarkers of inflammation, of endothelial dysfunction, glycated haemoglobin, and their reflection in arterial dilatation, in patients with type 2 diabetes mellitus and in their relatives, in order to demonstrate if relatives present markers as a form of precocious indicators of diabetes mellitus. Individuals between 30 and 55 years of age and without clinical arterial disease were divided in three groups: type 2 diabetes mellitus patients without complications (12 men and 18 women); first degree relatives of type 2 diabetes mellitus (14 men and 20 women); and control individuals (9 men and 16 women). Body composition was measured with a bioelectrical impedance analyzer and endothelial function with an eco-Doppler device. We determined glucose, insulin, C-peptide, glycated haemoglobin, fibrinogen, E-selectin, P-selectin, soluble intercellular cell adhesion molecule-1 (ICAM-1), soluble vascular cell adhesion molecule-1 (VCAM-1), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), C-reactive protein (CRP) in plasma. We also studied endothelium independent dilatation and endothelium dependent dilatation.

THE RESULTS

ICAM-1 and VCAM-1 were significantly higher in the diabetic group (237.5+/-43.4 and 692.5+/-168.6 ng/l) than in controls (197.4+/-51.2 and 573.5+/-121.1 ng/l, p=0.011 and 0.013, respectively), but were not higher in the family group (224.5+/-45.2 and 599.8+/-150.4 ng/l). CRP was higher in the diabetic group (3.35+/-3.27 mg/l) than in the other groups (1.28+/-1.29 and 1.61+/-1.54 mg/l, p=0.002) and correlated with glycated haemoglobin. The non-endothelium mediated dilatation was lesser in the diabetic group than in the family group (17.3+/-6.1 vs. 24+/-8, p=0.029) and controls. In conclusion patients with uncomplicated type 2 diabetes, but not their relatives, have biochemical markers of sub-clinical inflammation in relationship with glycated haemoglobin and dysfunction of the endothelial cells markers. In these patients endothelium independent dilatation is more affected than endothelium dependent dilatation.

Inflammation and coronary angiography in asymptomatic type 2 diabetic subjects

OBJECTIVE

Coronary artery disease (CAD) is prevalent in patients with type 2 diabetes mellitus (T2DM) and because it is often asymptomatic and extensive in comparison with CAD in subjects without diabetes, it represents a diagnostic challenge. The objective of the study was to investigate the prevalence of CAD in asymptomatic T2DM patients utilizing angiography and to investigate its association with cardiovascular (CV) risk factors, the metabolic syndrome and markers of inflammation.

MATERIAL AND METHODS

Eighty-two patients with T2DM without symptoms of CAD, and with >or=1 CV risk factor (hypertension, dyslipidaemia, premature familial CAD, smoking or microalbuminuria) underwent a diagnostic stress test and coronary angiography irrespective of stress test results. Stenosis detected in the main coronary arteries >or=50% of lumen diameter was categorized as one-, two- or three-vessel disease. Inflammatory markers were analysed in fasting samples.

RESULTS

Fifteen men and two women had significant CAD (21%) (1-vessel disease, n=10; 2- or 3-vessel disease, n=7). Patients with 2- or 3-vessel disease were significantly older and had a longer duration of diabetes, but the prevalence of other traditional CV risk factors or the metabolic syndrome was similar among those with 1-vessel and those with 2- or 3-vessel disease. Sensitivity for CAD of the stress test was low (0.35). The mean level of the pro-inflammatory marker interleukin-6 was elevated in patients with 2- to 3-vessel CAD as compared to patients with no or 1-vessel CAD (p<0.05).

CONCLUSIONS

Significant CAD was found in 21% of asymptomatic patients with T2DM with >or=1 CV risk factor. Inflammatory markers may be helpful in identifying patients that are likely to have significant CAD, but larger studies are warranted.

Therapeutic regulation of endothelial dysfunction in type 2 diabetes mellitus

Endothelial dysfunction is universal in diabetes, being intimately involved with the development of cardiovascular disease. The pathogenesis of endothelial dysfunction in diabetes is complex. It is initially related to the effects of fatty acids and insulin resistance on 'uncoupling' of both endothelial nitric oxide synthase activity and mitochondrial function. Oxidative stress activates protein kinase C (PKC), polyol, hexosamine and nuclear factor kappa B pathways, thereby aggravating endothelial dysfunction. Improvements in endothelial function in the peripheral circulation in diabetes have been demonstrated with monotherapies, including statins, fibrates, angiotensin-converting enzyme (ACE) inhibitors, metformin and fish oils. These observations are supported by large clinical end point trials. Other studies show benefits with certain antioxidants, L-arginine, folate, PKC-inhibitors, peroxisome proliferator activated receptor (PPAR)-alpha and -gamma agonists and phosphodiesterase (PDE-5) inhibitors. However, the benefits of these agents remain to be shown in clinical end point trials. Combination treatments, for example, statins plus ACE inhibitors and statins plus fibrates, have also been demonstrated to have additive benefits on endothelial function in diabetes, but there are no clinical outcome data to date. Measurement of endothelial dysfunction in cardiovascular research can provide fresh opportunities for exploring the mechanism of benefit of new therapeutic regimens and for planning and designing large clinical trials.

Hind Limb Ischemia-Reperfusion in the Leptin Receptor Deficient (db/db) Mouse

BACKGROUND

Diabetic patients have high incidence of peripheral vascular disease and limb loss after acute extremity injury. Experiments were designed to test the hypothesis that acute tissue injury in leptin receptor deficient (Db) diabetic (type2) mice would be more severe than in non-diabetic mice.

METHODS

Db and wild type (Wt) mice were subjected to 3 h of ischemia followed by either 4 or 24 h of reperfusion (3/4 IR, 3/24 IR). Muscle analyzed for tissue viability (mitochondrial activity), cytokines (KC-murine equivalent of human IL-8, TNFalpha, IL-6), growth factor, and histological evaluation (neutrophils/uninjured muscle fibers). Tissue perfusion was detected during basal and reperfusion conditions using laser Doppler imaging.

RESULTS

Mitochondrial activity and histological evaluation for tissue injury did not differ in the Db versus Wt mice at the time intervals studied. When compared with their respective sham animals, both Db and Wt mice had similarly increased levels of KC, IL-6, and VEGF after 3/24 IR. TNFalpha levels increased in Db but not Wt mice after IR. Although absolute increases in TNFalpha and KC were higher in Db mice, VEGF levels were actually lower in the Db mice.

CONCLUSION

The patterns of tissue perfusion, cytokines, and growth factors were different in Db versus Wt mice. At the acute time intervals studied, these differences did not correlate with an expected greater degree of acute muscle injury in Db mice.

Novel therapies targeting vascular endothelium

Endothelial dysfunction has been identified as a major mechanism involved in all the stages of atherogenesis. Evaluation of endothelial function seems to have a predictive role in humans, and therapeutic interventions improving nitric oxide bioavailability in the vasculature may improve the long-term outcome in healthy individuals, high-risk subjects, or patients with advanced atherosclerosis. Several therapeutic strategies are now available, targeting both the synthesis and oxidative inactivation of nitric oxide (NO) in human vasculature. Statins seem to be currently the most powerful category of these agents, improving endothelial function and decreasing cardiovascular risk after long-term administration. Other cardiovascular agents improving endothelial function in humans are angiotensin-converting enzyme inhibitors/angiotensin receptors blockers, which increase NO bioavailability by modifying the rennin-angiotensin-aldosterone system. Newer therapeutic approaches targeting endothelial dysfunction in specific disease states include insulin sensitizers, L-arginine (the substrate for endothelial NO synthase [eNOS]) as well as substances that target eNOS "coupling," such as folates or tetrahydrobiopterin. Although there are a variety of strategies to improve NO bioavailability in human endothelium, it is still unclear whether they have any direct benefit at a clinical level.

Tumor necrosis factor alpha influences the inflammatory response after coronary surgery

BACKGROUND

A systemic inflammatory response is not uncommonly observed after coronary revascularization. Tumor necrosis factor alpha is one of a number of modulators of this response. A functional polymorphism within the TNFalpha gene at position G-308A has been associated with increased TNFalpha levels. The relationship between predicted TNFalpha genotype and circulating TNFalpha levels in patients undergoing coronary revascularization surgery has yet to be defined. We examined the relationship between TNFalpha G-308A polymorphism, TNFalpha postoperative levels, and clinical outcome after coronary revascularization surgery.

METHODS

We obtained DNA from 96 consecutive patients who underwent elective coronary revascularization. Patients were genotyped for TNFalpha G-308A polymorphism using sequence specific primer-polymerase chain reaction (SSP-PCR). Tumor necrosis factor alpha levels were measured on serum samples taken 3 hours postoperatively using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The prevalence of AA, AG, and GG TNFalpha-308 genotype was 12%, 40%, and 48%, respectively. Patients homozygous for A had higher circulating levels of TNFalpha (p = 0.009). Higher levels of TNFalpha were significantly associated with prolonged intensive care unit stay (p = 0.008), increase usage of an inotropic agent (p = 0.024), increased mortality risk (p = 0.018), and diabetes (p = 0.019). These remained statistically significant after risk stratification.

CONCLUSIONS

Patients of the AA-308 TNFalpha genotype showed significantly higher TNFalpha plasma levels. Higher plasma levels of TNFalpha were associated with less favorable outcome after coronary revascularization surgery. It may prove useful to utilize TNFalpha serum levels as a marker for identifying high-risk patients in the future.

Comparison of the antioxidant and vascular effects of gliclazide and glibenclamide in Type 2 diabetic patients: a randomized crossover study

The aim of the present study is to compare the short-term effects of gliclazide and glibenclamide on the oxidative state and vascular endothelium function of Type 2 diabetic patients in an observer-blinded, randomized crossover study. Thirteen Type 2 diabetic patients were enrolled: one group of seven patients took daily 160 mg of gliclazide for the first 4 weeks and then daily 5 mg of glibenclamide for the next 4 weeks; another group of six patients took daily 5 mg of glibenclamide for the first 4 weeks and 160 mg of gliclazide for the next 4 weeks. Forearm blood flow (FBF) measurement for endothelial function and biochemical analyses were conducted before and after each crossover treatment. Four weeks of treatment with either sulfonylurea showed the similar antihyperglycemic effects and enhancement of the peak FBF and total reactive hyperemic flow (flow debt repayment: FDR) during reactive hyperemia. Treatment with gliclazide resulted in the significant reduction to about 60% of baseline in urinary 8-iso-prostaglandin F2alpha (8iPGF2alpha) excretion while no such change was detected in the glibenclamide period. The increases in peak FBF and FDR were in parallel with its anti-hyperglycemic effect, but not with antioxidant state. Results suggest that gliclazide and glibenclamide can protect vascular endothelium from hyperglycemia-induced injury in Type 2 diabetic patients.

Vascular adrenergic tone and structural narrowing constrain reactive hyperemia in skeletal muscle of obese Zucker rats

Previous studies have demonstrated that skeletal muscle perfusion is impaired in obese Zucker rats (OZR) under control conditions and with elevated metabolic demand versus responses in lean Zucker rats (LZR). To further our understanding of processes contributing to impaired perfusion, we determined whether hyperemic responses following periods of occlusion were altered in skeletal muscle of OZR versus LZR. In isolated hindlimbs, basal blood flow in OZR was less than in LZR, and total perfusion responses after 30, 90, and 180 s of occlusion were reduced. Treatment of animals with an antioxidant (polythethylene glycol-superoxide dismutase) had no effect on reactive hyperemia, although blockade of alpha-adrenoreceptors (alpha1 > alpha2) improved responses to 30 and 90 s of occlusion; responses to 180 s of occlusion were unaltered. Pump perfusion of a dilated distal hindlimb demonstrated that increased volume flow elicited a greater increase in perfusion pressure in OZR versus LZR, suggesting structural contributions to an increased vascular resistance. Responses were comparable for in situ cremaster muscle because reactive hyperemia following serial arteriolar occlusion was attenuated in OZR versus LZR, treatment with polythethylene glycol-superoxide dismutase was ineffective, and hyperemic responses were improved following inhibition of alpha-adrenoreceptors (alpha1 > alpha2). Treatment of cremaster muscle with adenosine (10(-3) M) caused flow to increase to a level comparable to that following 180 s of occlusion in both strains, although this level was reduced in OZR versus LZR. These results suggest that increased adrenergic tone may constrain reactive hyperemia in OZR with brief occlusion, although structural increases in vascular resistance can contribute to constrained perfusion after longer periods of occlusion.

Endothelial function and inflammation in coronary artery disease

Evidence supports the central role of endothelium and inflammation in all phases of the atherosclerotic process. Clinical studies have shown their prognostic potential for the development of ischaemic events and for adverse outcome after acute coronary syndromes. Reduction in inflammatory levels and improving endothelial function by traditional and novel treatment strategies were associated with a proportional reduction in cardiovascular events. However, randomised controlled trials are required to explore further whether drugs targeting the inflammatory process and endothelial function will constitute a reasonable adjunctive treatment for patients with coronary artery disease.