Very low-density lipoprotein activates nuclear factor-kappaB in endothelial cells

Cross-sectional study of lipoprotein(a) and the severity of coronary artery disease, cerebrovascular disease, and peripheral vascular disease in a group of South Asian patients

Background

Atherosclerotic cardiovascular diseases (ASCVD), including coronary artery disease (CAD), cerebrovascular disease (CVD), and peripheral vascular disease (PVD), remain the leading cause of death globally. South Asians exhibit a higher incidence of cardiovascular diseases than other ethnicities, attributed to a range of genetic, environmental, and lifestyle factors. Lipoprotein(a) [Lp(a)] with a unique apolipoprotein(a) component, has emerged as a marker of atherosclerosis and ASCVD risk, with evidence to promote arterial plaque formation and thrombogenesis.

Objective

The aim of this study was to explore the associations between Lp(a) levels and the severity of CAD, CVD, and PVD in a group of South Asian patients.

Methods

Following ethical approval, 60 consecutive patients who underwent coronary angiography for any indication were reviewed. There were 51 eligible participants who were evaluated for Lp(a) level, Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score, and severity of CVD and PVD. The SYNTAX-I score was calculated using two-observer consensus on coronary angiograms. Assessment of CVD was by ultrasound/Doppler, and PVD by estimating ankle-brachial index using Doppler. The multisite arterial disease score 2 (MADS2) and SYNTAX score tertiles were used to group the patients. Statistical analysis was performed using the SPSS software.

Results and discussion

In this group, we identified a statistically significant difference with higher Lp(a) levels being associated with more severe coronary disease (SYNTAX tertile 2,3). Despite a numerical trend, statistical significance was not confirmed for Lp(a) levels in relation to MADS2-CVD or MADS2-PVD scores. A larger study may be required to assess these aspects.

Overexpression of ABCA1 in Carotid Endothelium of Hyperlipidemic Rabbits Modulates Vascular Inflammation

Endothelial activation and dysfunction are key early steps in atherogenesis. Vascular gene therapy targeting endothelial inflammation and cholesterol accumulation could decrease atherosclerosis progression. ATP-binding cassette subfamily A member 1 (ABCA1) exhibits anti-inflammatory properties and promotes cholesterol efflux. A mouse model showed that systemic endothelial overexpression of ABCA1 decreased diet-induced atherosclerosis. To test if local ABCA1 endothelial overexpression protects against atherosclerosis, we used helper-dependent adenoviral vectors (HDAd) to express ABCA1 or a "Null" control in the carotid endothelium of hyperlipidemic rabbits. Both ABCA1 mRNA and endothelial protein were increased 3 days after vector infusion. After 24 weeks on a high-fat diet, laser-microdissected endothelium showed increased ABCA1 mRNA expression, but whole-vessel ABCA1 mRNA was decreased with HDAdABCA1. Endothelial ABCA1 protein could not be measured at 24 weeks, so its overexpression may be transient. CD68 expression was decreased (-23%, p < 0.001), but ITGAM (-15%, p = 0.3) was unchanged. Macrophage markers for both M1-like macrophages (IL1B: -44% [p = 0.02]; IL6: -40% [p = 0.02]; CCL2: -25% [p = 0.02]) and M2-like macrophages (ARG1: -27% [p = 0.03]; IL10: -23% [p = 0.09]; TGFB1: -13% [p < 0.001]) were also decreased. The inflammatory cytokines IL6 (-100%; p < 0.001) and TNF (p < 0.05) were significantly decreased in the laser-microdissected endothelium, but VCAM1 (+5%, p = 1.0) was unchanged and ICAM1 (+101%; p = 0.03) increased. Lesion size, intimal lipid, and intimal macrophage content were all unchanged (p > 0.5 for all), and vascular cholesterol measured by mass spectrometry (-11%; p = 0.9) also showed no difference. There was a small decrease in the intimal/medial ratio. scRNAseq revealed that vector transcripts were not restricted to endothelial cells after 24+ weeks but were detected in most cell types. The exception was modulated smooth muscle cells, which were found in substantial numbers in larger lesions. Overall, transient overexpression of ABCA1 in the vascular endothelium subtly alters the expression of inflammatory markers, providing only a modest atheroprotection.

Impact of the COVID-19 Pandemic on Obesity, Metabolic Parameters and Clinical Values in the South Korean Adult Population

This study aimed to evaluate the effects of the COVID-19 pandemic on obesity, metabolic parameters, and clinical values in the South Korean population. Data from the seventh and eighth National Health and Nutrition Examination Surveys were analyzed, comprising 3560 participants in 2018 (pre-COVID-19) and 3309 participants in 2021 (post-COVID-19). The study focused on adults aged 19 years and older who were overweight (BMI ≥ 25 kg/m2). The results showed a significant increase in waist circumference (approximately 2 cm), BMI (approximately 0.11 kg/m2), systolic blood pressure, fasting blood sugar (1.76 mg/dL higher), and glycated hemoglobin (0.14% higher) in the post-COVID-19 group compared to the pre-COVID-19 group. Additionally, the prevalence of hypercholesterolemia increased by 4% after the COVID-19 pandemic. These findings suggest an increased risk of obesity, abdominal obesity, and metabolic disorders, such as blood sugar disorders, in the post-COVID-19 period. Urine analysis revealed abnormal findings, including occult blood, urobilinogen, hematuria, proteinuria, ketone urea, glycosuria, and bacteriuria. The study highlights the negative impact of lifestyle changes, such as reduced physical activity and social gatherings, on physical vital signs and clinical values during the COVID-19 pandemic.

The Link between miRNAs and PCKS9 in Atherosclerosis

Cardiovascular disease (CDV) represents the major cause of death globally. Atherosclerosis, as the primary cause of CVD, is a chronic immune-inflammatory disorder with complex multifactorial pathophysiology encompassing oxidative stress, enhanced immune-inflammatory cascade, endothelial dysfunction, and thrombosis. An initiating event in atherosclerosis is the subendothelial accumulation of low-density lipoprotein (LDL), followed by the localization of macrophages to fatty deposits on blood vessel walls, forming lipid-laden macrophages (foam cells) that secrete compounds involved in plaque formation. Given the fact that foam cells are one of the key culprits that underlie the pathophysiology of atherosclerosis, special attention has been paid to the investigation of the efficient therapeutic approach to overcome the dysregulation of metabolism of cholesterol in macrophages, decrease the foam cell formation and/or to force its degradation. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secretory serine proteinase that has emerged as a significant regulator of the lipid metabolism pathway. PCSK9 activation leads to the degradation of LDL receptors (LDLRs), increasing LDL cholesterol (LDL-C) levels in the circulation. PCSK9 pathway dysregulation has been identified as one of the mechanisms involved in atherosclerosis. In addition, microRNAs (miRNAs) are investigated as important epigenetic factors in the pathophysiology of atherosclerosis and dysregulation of lipid metabolism. This review article summarizes the recent findings connecting the role of PCSK9 in atherosclerosis and the involvement of various miRNAs in regulating the expression of PCSK9-related genes. We also discuss PCSK9 pathway-targeting therapeutic interventions based on PCSK9 inhibition, and miRNA levels manipulation by therapeutic agents.

The relationship between metabolic syndrome criteria and pentraxin-3 levels in children

OBJECTIVES

While the positive correlation was shown in a few studies which investigated the relationship between obesity and pentraxin-3 (PTX-3) levels, different findings were obtained in other studies. We aimed to determine PTX-3 levels in obese and healthy children, and their relationship with Metabolic Syndrome (MetS) criteria.

METHODS

105 children and adolescents were considered as the study population. Participants were divided into three groups; obese and MetS (OM+), obese and non-MetS (OM-) and the control group. Fasting glucose, blood lipids and PTX-3 levels were measured. Ultrasonography was performed to detect hepatic steatosis. MetS and hepatic steatosis were investigated by dividing the patients into two groups according to PTX-3 levels.

RESULTS

The study population consisted of 37 patients with OM+; 35 patients with OM- and 33 healthy children. OM+ patients had higher fasting insulin (p<0.001), homeostatic model assessment for insulin resistance (p<0.001), triglyceride (p<0.001) and lower high-density lipoprotein (p=0.001). The PTX-3 level was higher in the OM+ group compared to both OM- group and the control group (p=0.002). When two groups were generated according to PTX-3 level, a higher frequency of MetS was detected in the high PTX 3 group than in all three major MetS diagnostic criteria groups. Moreover, there was more hepatic steatosis in the high PTX-3 group independent from obesity and MetS.

CONCLUSIONS

Higher PTX-3 levels were present in children and adolescent obese patients with MetS.

Serum Bilirubin and Markers of Oxidative Stress and Inflammation in a Healthy Population and in Patients with Various Forms of Atherosclerosis

Oxidative stress and inflammation contribute significantly to atherogenesis. We and others have demonstrated that mildly elevated serum bilirubin levels protect against coronary and peripheral atherosclerosis, most likely due to the antioxidant and anti-inflammatory activities of bilirubin. The aim of the present study was to assess serum bilirubin and the markers of oxidative stress and inflammation in both healthy subjects and patients with various forms of atherosclerosis. The study was performed in patients with premature myocardial infarction (n = 129), chronic ischemic heart disease (n = 43), peripheral artery disease (PAD, n = 69), and healthy subjects (n = 225). In all subjects, standard serum biochemistry, UGT1A1 genotypes, total antioxidant status (TAS), and concentrations of various pro- and anti-inflammatory chemokines were determined. Compared to controls, all atherosclerotic groups had significantly lower serum bilirubin and TAS, while having much higher serum high-sensitivity C-reactive protein (hsCRP) and most of the analyzed proinflammatory cytokines (p < 0.05 for all comparisons). Surprisingly, the highest inflammation, and the lowest antioxidant status, together with the lowest serum bilirubin, was observed in PAD patients, and not in premature atherosclerosis. In conclusion, elevated serum bilirubin is positively correlated with TAS, and negatively related to inflammatory markers. Compared to healthy subjects, patients with atherosclerosis have a much higher degree of oxidative stress and inflammation.

Triglyceride and Triglyceride-Rich Lipoproteins in Atherosclerosis

Cardiovascular disease (CVD) is still the leading cause of death globally, and atherosclerosis is the main pathological basis of CVDs. Low-density lipoprotein cholesterol (LDL-C) is a strong causal factor of atherosclerosis. However, the first-line lipid-lowering drugs, statins, only reduce approximately 30% of the CVD risk. Of note, atherosclerotic CVD (ASCVD) cannot be eliminated in a great number of patients even their LDL-C levels meet the recommended clinical goals. Previously, whether the elevated plasma level of triglyceride is causally associated with ASCVD has been controversial. Recent genetic and epidemiological studies have demonstrated that triglyceride and triglyceride-rich lipoprotein (TGRL) are the main causal risk factors of the residual ASCVD. TGRLs and their metabolites can promote atherosclerosis via modulating inflammation, oxidative stress, and formation of foam cells. In this article, we will make a short review of TG and TGRL metabolism, display evidence of association between TG and ASCVD, summarize the atherogenic factors of TGRLs and their metabolites, and discuss the current findings and advances in TG-lowering therapies. This review provides information useful for the researchers in the field of CVD as well as for pharmacologists and clinicians.

Hypertriglyceridemia: A Neglected Risk Factor for Ischemic Stroke?

Hypertriglyceridemia is caused by defects in triglyceride metabolism and generally manifests as abnormally high plasma triglyceride levels. Although the role of hypertriglyceridemia may not draw as much attention as that of plasma cholesterol in stroke, plasma triglycerides, especially nonfasting triglycerides, are thought to be correlated with the risk of ischemic stroke. Hypertriglyceridemia may increase the risk of ischemic stroke by promoting atherosclerosis and thrombosis and increasing blood viscosity. Moreover, hypertriglyceridemia may have some protective effects in patients who have already suffered a stroke via unclear mechanisms. Therefore, further studies are needed to elucidate the role of hypertriglyceridemia in the development and prognosis of ischemic stroke.

Prenylcysteine oxidase 1, an emerging player in atherosclerosis

The research into the pathophysiology of atherosclerosis has considerably increased our understanding of the disease complexity, but still many questions remain unanswered, both mechanistically and pharmacologically. Here, we provided evidence that the pro-oxidant enzyme Prenylcysteine Oxidase 1 (PCYOX1), in the human atherosclerotic lesions, is both synthesized locally and transported within the subintimal space by proatherogenic lipoproteins accumulating in the arterial wall during atherogenesis. Further, Pcyox1 deficiency in Apoe^-/- mice retards atheroprogression, is associated with decreased features of lesion vulnerability and lower levels of lipid peroxidation, reduces plasma lipid levels and inflammation. PCYOX1 silencing in vitro affects the cellular proteome by influencing multiple functions related to inflammation, oxidative stress, and platelet adhesion. Collectively, these findings identify the pro-oxidant enzyme PCYOX1 as an emerging player in atherogenesis and, therefore, understanding the biology and mechanisms of all functions of this unique enzyme is likely to provide additional therapeutic opportunities in addressing atherosclerosis.

Epidemiology, Pathophysiology, Diagnosis and Treatment of Heart Failure in Diabetes

The cardiovascular disease continuum begins with risk factors such as diabetes mellitus (DM), progresses to vasculopathy and myocardial dysfunction, and finally ends with cardiovascular death. Diabetes is associated with a 2- to 4-fold increased risk for heart failure (HF). Moreover, HF patients with DM have a worse prognosis than those without DM. Diabetes can cause myocardial ischemia via micro- and macrovasculopathy and can directly exert deleterious effects on the myocardium. Hyperglycemia, hyperinsulinemia, and insulin resistance can cause alterations in vascular homeostasis. Then, reduced nitric oxide and increased reactive oxygen species levels favor inflammation leading to atherothrombotic progression and myocardial dysfunction. The classification, diagnosis, and treatment of HF for a patient with and without DM remain the same. Until now, drugs targeting neurohumoral and metabolic pathways improved mortality and morbidity in HF with reduced ejection fraction (HFrEF). Therefore, all HFrEF patients should receive guideline-directed medical therapy. By contrast, drugs modulating neurohumoral activity did not improve survival in HF with preserved ejection fraction (HFpEF) patients. Trials investigating whether sodium-glucose cotransporter-2 inhibitors are effective in HFpEF are on-going. This review will summarize the epidemiology, pathophysiology, and treatment of HF in diabetes.

Cerebral arterial architectonics and CFD simulation in mice with type 1 diabetes mellitus of different duration

Type 1 diabetes is a chronic autoimmune disease that affects tens of millions of people. Diabetes mellitus is one of the strongest factors in the development of cerebrovascular diseases. In this study we used NOD.CB17 Prkdcscid mice and the pharmacological model of type 1 diabetes mellitus of different duration to study changes in the cerebral vasculature. We used two combined approaches using magnetic resonance angiography both steady and transient CFD blood flow modeling. We identified the influence of type 1 diabetes on the architectonics and hemodynamics of the large blood vessels of the brain as the disease progresses. For the first time, we detected a statistically significant change in angioarchitectonics (the angles between the vessels of the circle of Willis, cross-sections areas of vessels) and hemodynamic (maximum blood flow rate, hydraulic resistance) in animals with diabetes duration of 2 months, that is manifested by the development of asymmetry of cerebral blood flow. The result shows the negative effect of diabetes on cerebral circulation as well as the practicability of CFD modeling. This may be of extensive interest, in pharmacological and preclinical studies.

High Levels of Soluble Lectinlike Oxidized Low-Density Lipoprotein Receptor-1 Are Associated With Carotid Plaque Inflammation and Increased Risk of Ischemic Stroke

Background When the lectinlike oxidized low-density lipoprotein (ox LDL) receptor-1 ( LOX -1), a scavenger receptor for ox LDL , binds ox LDL , processes leading to endothelial dysfunction and inflammation are promoted. We aimed to study release mechanisms of LOX -1 and how circulating levels of soluble LOX -1 ( sLOX -1) relate to plaque inflammation and future risk for ischemic stroke. Methods and Results Endothelial cells and leukocytes were used to study release of sLOX -1. Plasma levels of sLOX -1 were determined in 4703 participants in the Malmö Diet and Cancer cohort. Incidence of ischemic stroke was monitored. For 202 patients undergoing carotid endarterectomy, levels of sLOX -1 were analyzed in plasma and plaque homogenates and related to plaque inflammation factors. Endothelial cells released sLOX -1 when exposed to ox LDL . A total of 257 subjects experienced stroke during a mean follow-up of 16.5 years. Subjects in the highest tertile of sLOX -1 had a stroke hazard ratio of 1.75 (95% CI, 1.28-2.39) compared with those in the lowest tertile after adjusting for age and sex. The patients undergoing carotid endarterectomy had a significant association between plasma sLOX -1 and the plaque content of sLOX -1 ( r=0.209, P=0.004). Plaques with high levels of sLOX -1 had more ox LDL , proinflammatory cytokines, and matrix metalloproteinases. Conclusions Our findings demonstrate that ox LDL induces the release of sLOX -1 from endothelial cells and that circulating levels of sLOX -1 correlate with carotid plaque inflammation and risk for ischemic stroke. These observations provide clinical support to experimental studies implicating LOX -1 in atherosclerosis and its possible role as target for cardiovascular intervention.

Protective Effect of Ginkgolic Acid in Attenuating LDL Induced Inflammation Human Peripheral Blood Mononuclear Cells via Altering the NF-κB Signaling Pathway

Oxidized low-density lipoprotein (ox-LDL) is considered as the significant maker of inflammatory reaction. ox-LDL was reported to play a crucial role in the pathogenesis of atherosclerosis (AS). In the current study, we scrutinize the suppressive effect of ginkgolic acid against ox-LDL induced an oxidative and inflammatory response in human microvascular endothelial cells (HMEC-1) and human peripheral blood mononuclear cells (nPBMCs) and explore the mechanism of action. HMEC-1 cells are treated with ox-LDL in the presence of different concentration of ginkgolic acid. MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was performed for the estimation of cell viability effect. Reactive oxygen species (ROS), inflammatory cytokines, and NF-κB activity are also estimated. For the hPBMCs assay, the cells were isolated from the healthy volunteers and cultured. The cells were further divided into different group and received the ginkgolic acid. Additionally, ROS, inflammatory marker such as prostaglandin E2 (PGE2), lipoxygenase (LOX), nitric oxide (NO), cyclooxygenase (COX) protein expression, and mRNA expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and vascular cell adhesion protein 1 (VCAM-1) were estimated in the ox-LDL treated group. The result exhibited that ginkgolic acid treatment induced the cell viability boosting in ox-LDL treatment and intracellular ROS significantly decreased by ginkgolic acid. Pro-inflammatory cytokines also downregulated via ginkgolic acid. Moreover, ginkgolic acid reduced the ox-LDL-induced NF-κB. The mRNA and protein expression of TNF-α, IL-6, and VCAM-1 considerably increased in the ox-LDL treated group and ginkgolic acid significantly reduced the mRNA and protein expression. An inflammatory marker such as PGE2, LOX, and NO were increased in the ox-LDL treated group and ginkgolic acid treated group exhibited the reduction of an inflammatory marker. Based on the result, we can conclude that ginkgolic acid significantly reduced and reversed the ox-LDL-induced modulation, suggesting its anti-inflammatory effect via the NF-κB pathway.

Oxidative Stress in Cardiovascular Diseases: Still a Therapeutic Target?

Cardiovascular diseases (CVD) are complex entities with heterogenous pathophysiologic mechanisms and increased oxidative stress has been viewed as one of the potential common etiologies. A fine balance between the presence of reactive oxygen species (ROS) and antioxidants is essential for the proper normal functioning of the cell. A basal concentration of ROS is indispensable for the manifestation of cellular functions, whereas excessive levels of ROS cause damage to cellular macromolecules such as DNA, lipids and proteins, eventually leading to necrosis and apoptotic cell death. CVD is the main cause of death worldwide with several conditions being affected by oxidative stress. Increased ROS lead to decreased nitric oxide availability and vasoconstriction, promoting arterial hypertension. ROS also negatively influence myocardial calcium handling, causing arrhythmia, and augment cardiac remodeling by inducing hypertrophic signaling and apoptosis. Finally, ROS have also been shown to promote atherosclerotic plaque formation. This review aims at giving an introduction into oxidative stress in CVD, with special focus on endothelial dysfunction, and then examining in detail the role of oxidative stress in the most prevalent of these diseases. Finally, potential nutraceuticals and diets that might be beneficial in diminishing the burden of oxidative stress in CVD are presented.

The Role of (Modified) Lipoproteins in Vascular Function: A Duet Between Monocytes and the Endothelium

Over the last century, many studies have demonstrated that low-density lipoprotein (LDL) is a key risk factor of cardiovascular diseases (CVD) related to atherosclerosis. Thus, for these CVD patients, LDL lowering agents are commonly used in the clinic to reduce the risk for CVD. LDL, upon modification, will develop distinct inflammatory and proatherogenic potential, leading to impaired endothelial integrity, influx of immune cells and subsequent increased foam cell formation. LDL can also directly affect peripheral monocyte composition, rendering them in a more favorable position to migrate and accumulate in the subendothelial space. It has become apparent that other lipoprotein particles, such as triglyceride- rich lipoproteins or remnants (TRL) and lipoprotein(a) [Lp(a)] may also impact on atherogenic pathways. Evidence is accumulating that Lp(a) can promote peripheral monocyte activation, eventually leading to increased transmigration through the endothelium. Similarly, remnant cholesterol has been identified to play a key role in endothelial dysfunction and monocyte behavior. In this review, we will discuss recent developments in understanding the role of different lipoproteins in the context of inflammation at both the level of the monocyte and the endothelium.

Pathobiological mechanisms underlying metabolic syndrome (MetS) in chronic obstructive pulmonary disease (COPD): clinical significance and therapeutic strategies

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and is currently the 4th largest cause of death in the world. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities (e.g. skeletal muscle wasting, ischemic heart disease, cognitive dysfunction) and infective viral and bacterial acute exacerbations (AECOPD). Current pharmacological treatments for COPD are relatively ineffective and the development of effective therapies has been severely hampered by the lack of understanding of the mechanisms and mediators underlying COPD. Since comorbidities have a tremendous impact on the prognosis and severity of COPD, the 2015 American Thoracic Society/European Respiratory Society (ATS/ERS) Research Statement on COPD urgently called for studies to elucidate the pathobiological mechanisms linking COPD to its comorbidities. It is now emerging that up to 50% of COPD patients have metabolic syndrome (MetS) as a comorbidity. It is currently not clear whether metabolic syndrome is an independent co-existing condition or a direct consequence of the progressive lung pathology in COPD patients. As MetS has important clinical implications on COPD outcomes, identification of disease mechanisms linking COPD to MetS is the key to effective therapy. In this comprehensive review, we discuss the potential mechanisms linking MetS to COPD and hence plausible therapeutic strategies to treat this debilitating comorbidity of COPD.

Oxidized LDL upregulates macrophage DPP4 expression via TLR4/TRIF/CD36 pathways

BACKGROUND

We and others have shown that dipeptidyl peptidase-IV (DPP4) expression is increased in obesity/atherosclerosis and is positively correlated with atherosclerotic burden. However, the mechanism by which DPP4 expression is regulated in obesity remains unclear. In this study, we investigated the pathways regulating the expression of DPP4 on macrophages.

METHODS

Flowsight® Imaging Flow Cytometry was employed for the detection of DPP4 and immunophenotyping. DPP4 enzymatic activity was measured by a DPPIV-Glo™ Protease Assay kit.

FINDINGS

Human monocytes expressed a moderate level of membrane-bound DPP4. Obese patients with body mass index (BMI) ≥ 30 had a higher level of monocyte DPP4 expression, in parallel with higher levels of HOMA-IR, blood glucose, triglycerides, and non-HDL cholesterol, compared to those in the non-obese (BMI < 30) patients. Oxidized low-density lipoprotein (oxLDL), but not native LDL, up-regulated DPP4 expression on macrophages with a preferential increase in CD36+ cells. OxLDL mediated DPP4 up-regulation was considerably diminished by Toll-like receptor-4 (TLR4) knockdown and CD36 deficiency. TRIF deficiency, but not MyD88 deficiency, attenuated oxLDL-induced DPP4 increase.

INTERPRETATION

Our study suggests a key role for oxLDL and downstream CD36/TLR4/TRIF in regulating DPP4 expression. Increased DPP4 in response to oxidized lipids may represent an integrated mechanism linking post-prandial glucose metabolism to lipoprotein abnormality-potentiated atherosclerosis.

Effects of diosgenin and its derivatives on atherosclerosis

The effects of diosgenin are discussed with respect to endothelial dysfunction, lipid profile, macrophage foam cell formation, VSMC viability, thrombosis and inflammation during the formation of atherosclerosis.

A Systematic Review on Natural Antioxidant Properties of Resveratrol

Polyphenols, including anthocyanins, flavonoids and stilbenes, which constitute one of the most abundant and ubiquitous groups of plant metabolites, are an integral part of the human diet. Resveratrol (3,5,4'-trihydroxystilbene), a naturally occurring polyphenol produced by some plants as a self-defence agent, has an antifungal activity. Resveratrol has been found in some plants (such as grapevine, pine and peanuts) and is considered to have beneficial effects also on human health. The number of studies on resveratrol greatly increased in PubMed database since 1997, after the anticancer effect of this molecule was first reported. The interest in resveratrol in grape was originally sparked by epidemiological studies indicating an inverse relationship between long-standing moderate consumption of red wine and the risk of coronary heart disease; this effect has been ascribed to resveratrol, which possesses diverse biochemical and physiological properties, including antiplatelet and anti-inflammatory proprieties, and provides a wide range of health benefits ranging from chemoprevention to cardioprotection. Recently, resveratrol has been described as an anti-aging compound. The consumption of resveratrol (red wine) together with a Mediterranean diet or a fast-food meal (“McDonald'sMeal”) had a positive impact on oxidized (ox-) LDL and on the expression of oxidative and inflammatory genes. Therefore, this review summarized the most important scientific data about healing and preventive potential of resveratrol, acting as cardioprotective, neuroprotective, chemopreventive and antioxidant agent.

Abnormal lipoprotein oxylipins in metabolic syndrome and partial correction by omega-3 fatty acids

Metabolic syndrome (MetSyn) is characterized by chronic inflammation which mediates the associated high risk for cardiovascular and other diseases. Oxylipins are a superclass of lipid mediators with potent bioactivities in inflammation, vascular biology, and more. While their role as locally produced agents is appreciated, most oxylipins in plasma are found in lipoproteins suggesting defective regulation of inflammation could be mediated by the elevated VLDL and low HDL levels characteristic of MetSyn. Our objective was to compare the oxylipin composition of VLDL, LDL, and HDL in 14 optimally healthy individuals and 31 MetSyn patients, and then to determine the effects of treating MetSyn subjects with 4g/day of prescription omega-3 fatty acids (P-OM3) on lipoprotein oxylipin profiles. We compared oxylipin compositions of healthy (14) and MetSyn (31) subjects followed by randomization and assignment to 4g/d P-OM3 for 16 weeks using LC/MS/MS. Compared to healthy subjects, MetSyn is characterized by abnormalities of (1) pro-inflammatory, arachidonate-derived oxylipins from the lipoxygenase pathway in HDL; and (2) oxylipins mostly not derived from arachidonate in VLDL. P-OM3 treatment corrected many components of these abnormalities, reducing the burden of inflammatory mediators within peripherally circulating lipoproteins that could interfere with, or enhance, local effectors of inflammatory stress. We conclude that MetSyn is associated with a disruption of lipoprotein oxylipin patterns consistent with greater inflammatory stress, and the partial correction of these dysoxylipinemias by treatment with omega-3 fatty acids could explain some of their beneficial effects.

Pretreatment with quercetin prevents changes in lymphocytes E-NTPDase/E-ADA activities and cytokines secretion in hyperlipidemic rats

Hyperlipidemia (HL) is a condition associated with endothelial dysfunction and inflammatory disorders. Purinergic system ectoenzymes play an important role in modulating the inflammatory and immune response. This study investigated whether the preventive treatment with quercetin is able to prevent changes caused by hyperlipidemia in the purinergic system, through the activities of E-NTPDase and E-ADA in lymphocytes, and quantify the nucleotides and nucleoside, and the secretion of anti- and proinflammatory cytokines. Animals were divided into saline/control, saline/quercetin 5 mg/kg, saline/quercetin 25 mg/kg, saline/quercetin 50 mg/kg, saline/simvastatin (0.04 mg/kg), hyperlipidemia, hyperlipidemia/quercetin 5 mg/kg, hyperlipidemia/quercetin 25 mg/kg, hyperlipidemia/quercetin 50 mg/kg, and hyperlipidemia/simvastatin. Animals were pretreated with quercetin for 30 days and hyperlipidemia was subsequently induced by intraperitoneal administration of 500 mg/kg of poloxamer-407. Simvastatin was administered after the induction of hyperlipidemia. Lymphocytes were isolated and E-NTPDase and E-ADA activities were determined. Serum was separated for the cytokines and nucleotide/nucleoside quantification. E-NTPDase and E-ADA activities were increased in lymphocytes from hyperlipidemic rats and pretreatment with quercetin was able to prevent the increase in the activities of these enzymes caused by hyperlipidemia. Hyperlipidemic rats when receiving pretreatment with quercetin and treatment with simvastatin showed decreased levels of ATP and ADP when compared to the untreated hyperlipidemic group. The IFN-γ and IL-4 cytokines were increased in the hyperlipidemic group when compared with control group, and decreased when hyperlipidemic rats received the pretreatment with quercetin. However, pretreatment with quercetin was able to prevent the alterations caused by hyperlipidemia probably by regulating the inflammatory process. We can suggest that the quercetin is a promising compound to be used as an adjuvant in the treatment of hyperlipidemia.

Apoprotein C-III: A review of its clinical implications

Apoprotein C-III (apoC-III), originating from the apoA-I/C-III/A-IV gene cluster affected by multiple regulating factors, has been demonstrated to have a validated link with hypertriglyceridemia in humans. Following genome studies establishing the impact of apoC-III on both plasma triglyceride (TG) level and cardiovascular disease (CVD), apoC-III offers us a novel explanation attempting to resolve the long-existing confusion with regard to the atherogenic effect of TG. Notably, apoC-III exerts its atherogenic effect by means of not only intervening in the function and metabolism of various lipid molecules, but also accelerating pro-inflammatory effects between monocytes and endothelial cells. Data have suggested that diabetes, a common endocrine disease, also correlates closely with apoC-III in its apoptosis process of islet βcells. In fact, apoC-III genes, with various mutations among individuals, are also found to have relevance to other diseases, including fatty liver disease. Fortunately, besides present day therapeutic strategies, such as lifestyle changes and lipid-lowering drug treatments, a promising new antisense drug specifically targeting on apoC-III gene expression opens up new avenues. This article mainly summarizes the clinical implication of apoC-III and its future directions of treatment.

Alleviation of high-fat diet-induced atherosclerosis and glucose intolerance by a novel GLP-1 fusion protein in ApoE(-/-) mice

We have previously constructed an engineered anti-diabetic fusion protein using glucagon-like peptide-1 and the globular domain of adiponectin. Herein, we evaluated the therapeutic effects of this fusion protein (GAD) on high-fat diet (HFD)-fed ApoE(-/-) mice. The lipid-lowering effect of GAD was determined in C57BL/6 mice using a lipid tolerance test. The effects of GAD on HFD-induced glucose intolerance, atherosclerosis, and hepatic steatosis were evaluated in HFD-fed ApoE(-/-) mice using glucose tolerance test, histological examinations and real-time quantitative PCR. The anti-inflammation activity of GAD was assessed in vitro on macrophages. GAD improved lipid metabolism in C57BL/6 mice. GAD treatment alleviated glucose intolerance, reduced blood lipid level, and attenuated atherosclerotic lesion in HFD-fed ApoE(-/-) mice, which was associated with a repressed macrophage infiltration in the vessel wall. GAD treatment also blocked hepatic macrophage infiltration and prevented hepatic inflammation. GAD suppressed lipopolysaccharide-triggered inflammation responses on macrophages, which can be abolished by H89, an inhibitor of protein kinase A. These findings demonstrate that GAD is able to generate a variety of metabolic benefits in HFD-fed ApoE(-/-) mice and indicate that this engineered fusion protein is a promising lead structure for anti-atherosclerosis drug discovery.

Oxidative stress, insulin resistance, dyslipidemia and type 2 diabetes mellitus

Oxidative stress is increased in metabolic syndrome and type 2 diabetes mellitus (T2DM) and this appears to underlie the development of cardiovascular disease, T2DM and diabetic complications. Increased oxidative stress appears to be a deleterious factor leading to insulin resistance, dyslipidemia, β-cell dysfunction, impaired glucose tolerance and ultimately leading to T2DM. Chronic oxidative stress, hyperglycemia and dyslipidemia are particularly dangerous for β-cells from lowest levels of antioxidant, have high oxidative energy requirements, decrease the gene expression of key β-cell genes and induce cell death. If β-cell functioning is impaired, it results in an under production of insulin, impairs glucose stimulated insulin secretion, fasting hyperglycemia and eventually the development of T2DM.

Imbalance between protective (adiponectin) and prothrombotic (Plasminogen Activator Inhibitor-1) adipokines in metabolic syndrome

AIMS

The metabolic syndrome (MS) consists of a constellation of metabolic abnormalities that confer increased risk of cardiovascular disease (CVD) and diabetes mellitus (DM). Visceral adipose tissue actively produces a variety of adipokines that interact in various obesity related disorders such as metabolic syndrome, diabetes mellitus and heart diseases. Adiponectin has protective role in the vascular physiology while Plasminogen Activator Inhibitor-1 (PAI-1) has a prothrombotic and consequent deleterious effect on the endothelium. We attempted to assess the putative imbalance if any between these two mediators in subjects with metabolic syndrome in the Indian context.

MATERIALS AND METHODS

We enrolled 50 diagnosed case of metabolic syndrome as per International Diabetes Federation (IDF) criteria and 50 healthy volunteers as control. Clinical evaluation included anthropometric, routine biochemical analysis as well as adiponectin and PAI-1 measurement.

RESULT

Subject with MS had significantly lower adiponectin (9.8±1.0 vs 16±1.1 μg/ml) and higher PAI-1 (232±87 vs 185±96 ng/ml). A statistically significant correlation was observed between adiponectin and HDL levels (r=0.388, p=0.005).

CONCLUSION

Subjects with MS have lower adiponectin and higher PAI-1 levels as compared to controls. The subsequent tilt toward a more prothrombotic and pro inflammatory milieu in the vascular endothelium may be pathognomonic of metabolic syndrome. This understanding of the still undiscovered subtle vascular alterations may help in the better management of obesity and MS.

New paradigms in inflammatory signaling in vascular endothelial cells

Inflammation is a basic cellular process in innate and adaptive immunity. Vascular endothelial cells play an important role in the initiation, amplification, and resolution of the inflammatory response. Deregulated inflammatory response is implicated in a variety of cardiovascular diseases such as atherosclerosis, obesity, diabetes, and hypertension. Recent studies have made significant progresses in the understanding of the complex molecular pathways that mediate the pro- and anti-inflammatory signaling in endothelial cells (ECs). Specifically, a number of macromolecular complexes termed as signalosomes have been identified to integrate the proinflammatory signaling from the membrane receptors to key transcription factors such as nuclear factor-κB (NF-κB). Inflammasomes are associated with the pattern-recognition receptors such as Toll-like receptors (TLRs), nucleotide-binding oligomerization-domain (NOD)-like receptors (NLRs) to mediate innate immunity responses. Emerging evidence has also revealed that noncoding microRNAs constitute a new class of intra- and intercellular signaling molecules to modulate inflammation in ECs. Thus this article will briefly summarize these new mechanisms with a special emphasis in the context of cardiovascular diseases.

Postprandial VLDL lipolysis products increase monocyte adhesion and lipid droplet formation via activation of ERK2 and NFκB

Postprandial lipemia is characterized by a transient increase in circulating triglyceride-rich lipoproteins such as very low-density lipoprotein (VLDL) and has been shown to activate monocytes in vivo. Lipolysis of VLDL releases remnant particles, phospholipids, monoglycerides, diglycerides, and fatty acids in close proximity to endothelial cells and monocytes. We hypothesized that postprandial VLDL lipolysis products could activate and recruit monocytes by increasing monocyte expression of proinflammatory cytokines and adhesion molecules, and that such activation is related to the development of lipid droplets. Freshly isolated human monocytes were treated with VLDL lipolysis products (2.28 mmol/l triglycerides + 2 U/ml lipoprotein lipase), and monocyte adhesion to a primed endothelial monolayer was observed using a parallel plate flow chamber coupled with a CCD camera. Treated monocytes showed more rolling and adhesion than controls, and an increase in transmigration between endothelial cells. The increased adhesive events were related to elevated expression of key integrin complexes including Mac-1 [α(m)-integrin (CD11b)/β2-integrin (CD18)], CR4 [α(x)-integrin (CD11c)/CD18] and VLA-4 [α4-integrin (CD49d)/β1-integrin (CD29)] on treated monocytes. Treatment of peripheral blood mononuclear cells (PBMCs) and THP-1 monocytes with VLDL lipolysis products increased expression of TNFα, IL-1β, and IL-8 over controls, with concurrent activation of NFkB and AP-1. NFκB and AP-1-induced cytokine and integrin expression was dependent on ERK and Akt phosphorylation. Additionally, fatty acids from VLDL lipolysis products induced ERK2-dependent lipid droplet formation in monocytes, suggesting a link to inflammatory signaling pathways. These results provide novel mechanisms for postprandial monocyte activation by VLDL lipolysis products, suggesting new pathways and biomarkers for chronic, intermittent vascular injury.

The relationship between dietary fatty acids and inflammatory genes on the obese phenotype and serum lipids

Obesity, a chronic low-grade inflammatory condition is associated with the development of many comorbidities including dyslipidemia. This review examines interactions between single nucleotide polymorphisms (SNP) in the inflammatory genes tumor necrosis alpha (TNFA) and interleukin-6 (IL-6) and dietary fatty acids, and their relationship with obesity and serum lipid levels. In summary, dietary fatty acids, in particular saturated fatty acids and the omega-3 and omega-6 polyunsaturated fatty acids, impact the expression of the cytokine genes TNFA and IL-6, and alter TNFα and IL-6 production. In addition, sequence variants in these genes have also been shown to alter their gene expression and plasma levels, and are associated with obesity, measures of adiposity and serum lipid concentrations. When interactions between dietary fatty acids and TNFA and IL-6 SNPs on obesity and serum lipid were analyzed, both the quantity and quality of dietary fatty acids modulated the relationship between TNFA and IL-6 SNPs on obesity and serum lipid profiles, thereby impacting the association between phenotype and genotype. Researching these diet–gene interactions more extensively, and understanding the role of ethnicity as a confounder in these relationships, may contribute to a better understanding of the inter-individual variability in the obese phenotype.

The influence of repeated administration of poloxamer 407 on serum lipoproteins and protease activity in mouse liver and heart

The effects of repeated administration of poloxamer 407 (P-407) on lipoprotein-cholesterol (LP-C) and lipoprotein-triglyceride (LP-TG) fractions and subfractions, as well as the effect on liver and heart proteases, were studied. Repeated administration of P-407 to male CBA mice resulted in a model of atherosclerosis with increased diastolic blood pressure; there was a drastic increase in total serum cholesterol and especially TG. A novel small-angle X-ray scattering method for the determination of the fractional and subfractional composition of LP-C and LP-TG was used. In chronically P-407-treated mice, P-407 significantly increased atherogenic low-density lipoprotein C (LDL-C) fractions, as well as intermediate-density lipoprotein C (IDL-C), and LDL₁₋₃-C subfractions, and very-low-density lipoprotein-C (VLDL-C) fractions, as well as VLDL₁₋₂-C and VLDL₃₋₅-C subfractions), to a lesser extent, the total anti-atherogenic high-density lipoprotein C (HDL-C) fraction, as well as HDL₂-C and HDL₃-C subfractions. Additionally, we demonstrated an increase in the serum chitotriosidase activity, without significant changes in serum matrix metalloprotease (MMP) activity. Morphological changes observed in P-407-treated mice included atherosclerosis in the heart and storage syndrome in the liver macrophages. P-407 significantly increased the activity of cysteine, aspartate proteases, and MMPs in the heart, and only the activity of cathepsin B and MMPs in the liver of mice. Thus, repeated administration of P-407 to mice induced atherosclerosis secondary to sustained dyslipidemia and formation of foamy macrophages in liver, and also modulated the activity of heart and liver proteases.

Role of the JAK/STAT signaling pathway in the pathogenesis of acute myocardial infarction in rats and its effect on NF-κB expression

The Janus kinase/signal transducer and activator of transcription pathway (JAK/STAT signaling pathway) is involved in the development of numerous cardiovascular diseases, although the specific role of this pathway in the pathogenesis of acute myocardial infarction (AMI) has not been elucidated. The purpose of this study was to evaluate the role of the JAK/STAT signaling pathway in the onset of AMI in rats. We also tested the effect of this pathway on nuclear factor κB (NF-κB) expression in the myocardium and tumor necrosis factor-α (TNF-α) levels in the plasma of AMI rats. An AMI rat model was successfully established and AG490 was used to block the JAK/STAT signaling pathway. The plasma TNF-α levels of AMI rats were measured by ELISA. The protein expression of NF-κB in the myocardial cells of AMI rats was detected by immunohistochemistry. The infarction area was significantly smaller in rats treated with AG490 after coronary artery ligation (group C) compared with that in the myocardial infarction control group (group B). The left ventricular mass indices in the sham surgery group (group A) and group C were significantly lower compared with those of group B. Plasma TNF-α concentrations in group B were significantly higher compared with those of groups A and C. There were significantly fewer cardiomyocytes positively exhibiting NF-κB protein expression in groups A and C compared with group B. The JAK/STAT signaling pathway is involved in the onset of myocardial infarction and may also be involved in left ventricular remodeling after myocardial infarction. The involvement of the JAK/STAT signaling pathway in the onset of myocardial infarction may be correlated with its effects on the expression of NF-κB and TNF-α.

Lipoteichoic acid induces surfactant protein-A biosynthesis in human alveolar type II epithelial cells through activating the MEK1/2-ERK1/2-NF-κB pathway

BACKGROUND

Lipoteichoic acid (LTA), a gram-positive bacterial outer membrane component, can cause septic shock. Our previous studies showed that the gram-negative endotoxin, lipopolysaccharide (LPS), could induce surfactant protein-A (SP-A) production in human alveolar epithelial (A549) cells.

OBJECTIVES

In this study, we further evaluated the effect of LTA on SP-A biosynthesis and its possible signal-transducing mechanisms.

METHODS

A549 cells were exposed to LTA. Levels of SP-A, nuclear factor (NF)-κB, extracellular signal-regulated kinase 1/2 (ERK1/2), and mitogen-activated/extracellular signal-regulated kinase kinase (MEK)1 were determined.

RESULTS

Exposure of A549 cells to 10, 30, and 50 μg/ml LTA for 24 h did not affect cell viability. Meanwhile, when exposed to 30 μg/ml LTA for 1, 6, and 24 h, the biosynthesis of SP-A mRNA and protein in A549 cells significantly increased. As to the mechanism, LTA enhanced cytosolic and nuclear NF-κB levels in time-dependent manners. Pretreatment with BAY 11-7082, an inhibitor of NF-κB activation, significantly inhibited LTA-induced SP-A mRNA expression. Sequentially, LTA time-dependently augmented phosphorylation of ERK1/2. In addition, levels of phosphorylated MEK1 were augmented following treatment with LTA.

CONCLUSIONS

Therefore, this study showed that LTA can increase SP-A synthesis in human alveolar type II epithelial cells through sequentially activating the MEK1-ERK1/2-NF-κB-dependent pathway.

Cyclophilin-A: a potential screening marker for vascular disease in type-2 diabetes

The pathophysiology of vascular disease in diabetes involves abnormalities in endothelial cells, vascular smooth muscle cells, and monocytes. The metabolic abnormalities that characterize diabetes, such as hyperglycemia, increased free fatty acids, and insulin resistance, each provoke molecular mechanisms that contribute to vascular dysfunction. Several molecules have been identified as risk markers, and have been studied to prevent progression of disease and long-term complications. Markers such as C-reactive protein and monocyte chemoattractant protein-1 are used to assess risk for adverse cardiac events, but elevated levels are possible due to the presence of other risk factors as part of the natural physiological defense mechanism. In this review we discuss potential of cyclophilin-A, a secreted oxidative-stress-induced immunophilin with diverse functions. We present evidence for a significant role of cyclophilin-A in the pathogenesis of atherosclerosis in diabetes, and its potential as a marker for vascular disease in type-2 diabetes.

Cellular and molecular effects of resveratrol in health and disease

Resveratrol, a natural polyphenol abundantly found in grape skins and red wine, possesses diverse biochemical and physiological actions, including anti-inflammatory, anti-oxidation, anti-proliferation and promotion of differentiation, and chemopreventive effects. Recently, it is attracting increased attention due to its health benefits, especially in common age-related diseases such as cardiovascular disease, cancer, type 2 diabetes, and neurological conditions. In this review, we discuss the latest cellular and molecular findings that account for the beneficial actions of resveratrol.

Teleost fish larvae adapt to dietary arachidonic acid supply through modulation of the expression of lipid metabolism and stress response genes

Dietary fatty acid supply can affect stress response in fish during early development. Although knowledge on the mechanisms involved in fatty acid regulation of stress tolerance is scarce, it has often been hypothesised that eicosanoid profiles can influence cortisol production. Genomic cortisol actions are mediated by cytosolic receptors which may respond to cellular fatty acid signalling. An experiment was designed to test the effects of feeding gilthead sea-bream larvae with four microdiets, containing graded arachidonic acid (ARA) levels (0·4, 0·8, 1·5 and 3·0 %), on the expression of genes involved in stress response (steroidogenic acute regulatory protein, glucocorticoid receptor and phosphoenolpyruvate carboxykinase), lipid and, particularly, eicosanoid metabolism (hormone-sensitive lipase, PPARα, phospholipase A2, cyclo-oxygenase-2 and 5-lipoxygenase), as determined by real-time quantitative PCR. Fish fatty acid phenotypes reflected dietary fatty acid profiles. Growth performance, survival after acute stress and similar whole-body basal cortisol levels suggested that sea-bream larvae could tolerate a wide range of dietary ARA levels. Transcription of all genes analysed was significantly reduced at dietary ARA levels above 0·4 %. Nonetheless, despite practical suppression of phospholipase A2 transcription, higher leukotriene B4 levels were detected in larvae fed 3·0 % ARA, whereas a similar trend was observed regarding PGE2 production. The present study demonstrates that adaptation to a wide range of dietary ARA levels in gilthead sea-bream larvae involves the modulation of the expression of genes related to eicosanoid synthesis, lipid metabolism and stress response. The roles of ARA, other polyunsaturates and eicosanoids as signals in this process are discussed.

Metabolic abnormalities and viral replication are associated with biomarkers of vascular dysfunction in HIV-infected children

OBJECTIVES

HIV-infected children may be at risk for premature cardiovascular disease. We compared levels of biomarkers of vascular dysfunction in HIV-infected children (with and without hyperlipidaemia) with those in HIV-exposed, uninfected (HEU) children enrolled in the Pediatric HIV/AIDS Cohort Study (PHACS), and determined factors associated with these biomarkers.

METHODS

A prospective cohort study was carried out. Biomarkers of inflammation [C-reactive protein (CRP), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP1)], coagulant dysfunction (fibrinogen and P-selectin), endothelial dysfunction [soluble intracellular cell adhesion molecule-1 (sICAM), soluble vascular cell adhesion molecule-1 (sVCAM) and E-selectin], and metabolic dysfunction (adiponectin) were measured in 226 HIV-infected and 140 HEU children. Anthropometry, body composition, lipids, glucose, insulin, HIV disease severity, and antiretroviral therapy were recorded.

RESULTS

The median ages of the children were 12.3 years in the HIV-infected group and 10.1 years in the HEU group. Body mass index (BMI) z-scores, waist and hip circumferences, and percentage body fat were lower in the HIV-infected children. Total and non-high-density lipoprotein (HDL) cholesterol and triglycerides were higher in HIV-infected children. HIV-infected children also had higher MCP-1, fibrinogen, sICAM and sVCAM levels. In multivariable analyses in the HIV-infected children alone, BMI z-score was associated with higher CRP and fibrinogen, but lower MCP-1 and sVCAM. Unfavourable lipid profiles were positively associated with IL-6, MCP-1, fibrinogen, and P- and E-selectin, whereas increased HIV viral load was associated with markers of inflammation (MCP-1 and CRP) and endothelial dysfunction (sICAM and sVCAM).

CONCLUSIONS

HIV-infected children have higher levels of biomarkers of vascular dysfunction than do HEU children. Risk factors associated with higher biomarkers include unfavourable lipid levels and active HIV replication.

Chronic exposure to high fatty acids impedes receptor agonist-induced nitric oxide production and increments of cytosolic Ca2+ levels in endothelial cells

Dyslipidemia is a common metabolic disorder in diabetes. Nitric oxide (NO) production from endothelium plays the primary role in endothelium-mediated vascular relaxation and other endothelial functions. Therefore, we investigated the effects of elevated free fatty acids (FFA) on the stimulation of NO production by phospholipase C (PLC)-activating receptor agonists (potent physiological endothelium-dependent vasodilators) and defined the possible alterations of signaling pathways implicated in this scenario. Exposure of bovine aortic endothelial cells (BAECs) to high concentrations of a mixture of fatty acids (oleate and palmitate) for 5 or 10 days significantly reduced NO production evoked by receptor agonists (bradykinin or ATP) in a time- and dose-dependent manner. Such defects were not associated with alterations of either endothelial NO synthase mass or inositol phospholipid contents but were probably due to reduced elevations of intracellular free Ca(2)(+) levels ([Ca(2)(+)](i)) under these conditions. Exposure of BAECs to FFA significantly attenuated agonist-induced [Ca(2)(+)](i) increases by up to 54% in a dose- and time-dependent manner. Moreover, bradykinin receptor affinity on the cell surface was significantly decreased by high concentrations of FFA. The morphology of BAECs was altered after 10-day culture with high FFA. Co-culture with protein kinase C (PKC) inhibitors or antioxidants was able to reverse the impairments of receptor agonist-induced NO production and [Ca(2)(+)](i) rises as well as the alteration of receptor affinity in BAECs exposed to FFA. These data indicate that chronic exposure to high FFA reduces NO generation in endothelial cells probably by impairing PLC-mediated Ca(2)(+) signaling pathway through activation of PKC and excess generation of oxidants.

Lipopolysaccharide stimulates syntheses of toll-like receptor 2 and surfactant protein-A in human alveolar epithelial A549 cells through upregulating phosphorylation of MEK1 and ERK1/2 and sequential activation of NF-κB

Surfactant proteins (SPs) and toll-like receptors (TLRs) contribute to regulation of sepsis-induced acute lung injury. Lipopolysaccharide (LPS) is one of the major causes of septic shock. This study was designed to evaluate the effects of LPS on the regulation of tlr-2 and sp-a gene expression in human alveolar epithelial A549 cells and the possible mechanisms. Exposure of A549 cells to LPS increased the expressions of TLR2 and SP-A mRNA and protein in time-dependent manners. A search using a bioinformatic approach found that there are several nuclear factor kappa-B (NF-κB)-DNA-binding motifs in the promoter region of the tlr2 and sp-a genes. Immunoblotting analyses revealed that exposure to LPS time-dependently enhanced the translocation of NF-κB from the cytoplasm to nuclei. Analyses of an electrophoretic mobility shift assay further showed that LPS augmented the transactivation activity of NF-κB to its consensus oligonucleotides in A549cells. Sequentially, treatment of A549 cells with LPS increased phosphorylation of extracellular signal-regulated kinase (ERK)1/2, p38-mitogen-activated protein kinase (p38MAPK), and MAPK kinase-1 (MEK1). Pretreatment with PD98059, an inhibitor of ERK1/2, significantly decreased LPS-induced TLR2 and SP-A mRNA expression.

Effects of acetyl-L-carnitine and oxfenicine on aorta stiffness in diabetic rats

BACKGROUND

We compared the haemodynamic and metabolic effects of acetyl-L-carnitine (one of the carnitine derivatives) and of oxfenicine (a carnitine palmitoyltransferase-1 inhibitor) in streptozotocin-induced diabetes in male Wistar rats.

MATERIALS AND METHODS

Diabetes was induced by a single tail vein injection of 55mgkg(-1) streptozotocin. The diabetic animals daily treated with either acetyl-L-carnitine (150mgkg(-1) in drinking water) or oxfenicine (150mgkg(-1) by oral gavage) for 8weeks,were compared with the untreated age-matched diabetic controls. Arterial wave reflection was derived using the impulse response function of the filtered aortic input impedance spectra. Thiobarbituric acid reactive substances (TBARS) measurement was used to estimate malondialdehyde (MDA) content.

RESULTS

Oxfenicine, but not acetyl-L-carnitine, increased total peripheral resistance in diabetes, which paralleled its elevation in plasma levels of free fatty acids. By contrast, acetyl-L-carnitine, but not oxfenicine, resulted in a significant increase in wave transit time and a decrease in wave reflection factor, suggesting that acetyl-L-carnitine may attenuate the diabetes-induced deterioration in systolic loading condition for the left ventricle. This was in parallel with its lowering of MDA/TBARS content in plasma and aortic walls in diabetes. Acetyl-L-carnitine therapy also prevented the diabetes-related cardiac hypertrophy, as evidenced by the reduction in ratio of the left ventricular weight to body weight.

CONCLUSION

 Acetyl-L-carnitine, but not oxfenicine, attenuates aortic stiffening and cardiac hypertrophy, possibly through its decrease of lipid oxidation-derived MDA/TBARS in the rats with insulin deficiency.

Resveratrol and cardiovascular health

Resveratrol (3,4',5-trihydroxystilbene) is a member of natural, plant-derived chemicals known as polyphenols and is attracting increased attention due to its diverse health benefits especially in case of cardiovascular disease, cancer, diabetes and neurological problems. Despite impressive gains in diagnosis and treatment, cardiovascular disease (CVD) remains a serious clinical problem and threat to public health. Resveratrol possesses potent antioxidant properties and has been shown to decrease low-density lipoprotein-cholesterol oxidation and platelet aggregation. This compound also possesses a range of additional cardioprotective and vasoprotective properties including antiatherosclerotic and vasorelaxation action. Resveratrol also has the capacity to interact with multiple molecular targets, which involve diverse intracellular pathways. Most well-known is the ability of resveratrol to activate sirtuins, a class of NAD(+)-dependent deacetylase that affect multiple transcription factors and other protein targets. Recently, resveratrol was found to induce autophagy and regenerate myocardial ischemic tissue treated with stem cells. Overall observation indicates that resveratrol has a high therapeutic potentials for the treatment of cardiovascular diseases.

Free fatty acids induce endothelial dysfunction and activate protein kinase C and nuclear factor-κB pathway in rat aorta

BACKGROUND

Insulin resistance is associated with an inappropriate elevation of plasma free fatty acids (FFAs) and endothelial dysfunction. In this study, we asked if elevated circulating FFA levels led to impaired insulin signaling and endothelial dysfunction in-vivo via activation of PKC-mediated inflammatory pathways.

METHODS

Sprague-Dawley (S-D) rats were infused with 1) 20% intralipid+heparin (FFA group) or 2) saline alone (Control group) for 6h. The intact aorta thoracica and aorta abdominalis were then removed. Aortic rings were isolated and evaluated for endothelial-dependent and non-dependent relaxation in an organ bath. The activities of eNOS and PKC were measured in endothelial homogenates prepared from endothelial cells harvested from the aorta. The expression levels of insulin signaling molecules IRS-1, Akt, eNOS, ERK1/ERK2, PKC-α, NFκB-p65 subunit and IκB-α in rat aortic endothelium were determined by immunohistochemistry and Western blot.

RESULTS

Elevation of FFAs resulted in a 35.9% reduction in the response to acetylcholine (p < 0.01), a 26% decline in plasma NOx levels (p < 0.05), a 53% decrease in eNOS activity and a 34 ± 9% inhibition in IRS-1 tyrosine phosphorylation (p < 0.05). We also found a 46% decrease in Akt phosphorylation and a 36% decrease in eNOS phosphorylation. FFA-induced endothelial insulin resistance was associated with 82% increase in total membrane-associated PKC activity, a 1.7-fold increase in total PKC-α protein, 1.29-fold decrease in IκB-α expression levels and 1.47-fold increase in NF-κB p65 subunit expression in rat aortic endothelium.

CONCLUSION

The molecular mechanisms underlying FFA-induced endothelial insulin resistance and eNOS inhibition may provide an important link implicating the PKC and IκB-α/NF-κB pathways in FFA-mediated inhibition of vascular insulin signaling.

Expanded network of inflammatory markers of atherogenesis: where are we now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesis via activation of monocytes/macrophages and T lymphocytes. Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Expanded Network of Inflammatory Markers of Atherogenesis: Where Are We Now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesisviaactivation of monocytes/macrophages and T lymphocytes.Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

The protective role of amla (Emblica officinalis Gaertn.) against fructose-induced metabolic syndrome in a rat model

We investigated the effects of amla (Emblica officinalis Gaertn.) on fructose-induced metabolic syndrome using a rat model. Male Wistar rats were fed a high-fructose (65 %) diet or standard chow for 1 week, and treated with an ethyl acetate (EtOAc) extract of amla, a polyphenol-rich fraction, at 10 or 20 mg/kg body weight per d, or vehicle, for 2 weeks. Serum glucose, TAG, total cholesterol and blood pressure levels of the high-fructose diet-fed rats were increased compared with those of the normal rats (P < 0·001). However, the EtOAc extract of amla ameliorated the high fructose-induced metabolic syndrome, including hypertriacylglycerolaemia and hypercholesterolaemia. Also, the elevated levels of hepatic TAG and total cholesterol in rats given the high-fructose diet were significantly reduced by 33·8 and 24·6 %, respectively (P < 0·001), on the administration of the EtOAc extract of amla at the dose of 20 mg/kg with the regulation of sterol regulatory element-binding protein (SREBP)-1 expression. The protein levels of PPARα and SREBP-2 were not affected by the feeding of the high-fructose diet or EtOAc extract of amla. In addition, oral administration of the amla extract at the dose of 20 mg/kg significantly inhibited the increased serum and hepatic mitochondrial thiobarbituric acid-reactive substance levels (21·1 and 43·1 %, respectively; P < 0·001). Furthermore, the amla extract inhibited the increase of cyclo-oxygenase-2 with the regulation of NF-κB and bcl-2 proteins in the liver, while the elevated expression level of bax was significantly decreased by 8·5 and 10·2 % at the doses of 10 and 20 mg/kg body weight per d, respectively. These findings suggest that fructose-induced metabolic syndrome is attenuated by the polyphenol-rich fraction of amla.

Contribution of insulin resistance to vascular dysfunction

Insulin is a vascular hormone, able to influence vascular cell responses. In this review, we consider the insulin actions on vascular endothelium and on vascular smooth muscle cells (VSMC) both in physiological conditions and in the presence of insulin resistance. In particular, we focus the relationships between activation of insulin signalling pathways of phosphatidylinositol-3 kinase (PI3-K) and mitogen-activated protein kinase (MAPK) and the different vascular actions of insulin, with a particular attention to the insulin ability to activate the pathway nitric oxide (NO)/cyclic GMP/PKG via PI3-K, owing to the peculiar relevance of NO in vascular biology. We also discuss the insulin actions mediated by the MAPK pathway (such as endothelin-1 synthesis and secretion and VSMC proliferation and migration) and by the interactions between the two pathways, both in insulin-sensitive and in insulin-resistant states. Finally, we consider the influence of free fatty acids, cytokines and endothelin on vascular insulin resistance.