Nitric oxide production is paradoxically decreased after weight reduction surgery in morbid obesity patients

Candidate SNP Markers Significantly Altering the Affinity of TATA-Binding Protein for the Promoters of Human Hub Genes for Atherogenesis, Atherosclerosis and Atheroprotection

Atherosclerosis is a systemic disease in which focal lesions in arteries promote the build-up of lipoproteins and cholesterol they are transporting. The development of atheroma (atherogenesis) narrows blood vessels, reduces the blood supply and leads to cardiovascular diseases. According to the World Health Organization (WHO), cardiovascular diseases are the leading cause of death, which has been especially boosted since the COVID-19 pandemic. There is a variety of contributors to atherosclerosis, including lifestyle factors and genetic predisposition. Antioxidant diets and recreational exercises act as atheroprotectors and can retard atherogenesis. The search for molecular markers of atherogenesis and atheroprotection for predictive, preventive and personalized medicine appears to be the most promising direction for the study of atherosclerosis. In this work, we have analyzed 1068 human genes associated with atherogenesis, atherosclerosis and atheroprotection. The hub genes regulating these processes have been found to be the most ancient. In silico analysis of all 5112 SNPs in their promoters has revealed 330 candidate SNP markers, which statistically significantly change the affinity of the TATA-binding protein (TBP) for these promoters. These molecular markers have made us confident that natural selection acts against underexpression of the hub genes for atherogenesis, atherosclerosis and atheroprotection. At the same time, upregulation of the one for atheroprotection promotes human health.

Mechanisms and clinical implications of endothelium-dependent vasomotor dysfunction in coronary microvasculature

Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.

Increase in arterial stiffness measures after bariatric surgery

BACKGROUND AND AIMS

The relationship between obesity and arterial stiffness is complex, with a potential interaction by age (inverse association at younger age and positive at older age) and conflicting reports on the effect of lifestyle-based weight loss on arterial stiffness. Little is understood about post-bariatric surgery changes in arterial stiffness. This study aimed to examine post-bariatric surgery changes in arterial stiffness and identify factors associated with greater changes in arterial stiffness.

METHODS

In 72 patients (mean age 44.5 years, 72.2% female), we evaluated two arterial stiffness measures, cardio-ankle vascular index (CAVI) and heart-ankle pulse wave velocity (haPWV), one month prior to and 6 months after bariatric surgery. Another follow-up visit was conducted 12 months after bariatric surgery in a subset of 58 participants.

RESULTS

Six months after bariatric surgery, an evident decrease was seen in body mass index, heart rate, and systolic blood pressure. In contrast, both CAVI and haPWV significantly increased at 6 months (+0.64 [0.42, 0.87] and +0.24 [0.04, 0.44] m/s, respectively). Among 58 patients with relevant data, CAVI and haPWV remained elevated 12 months after bariatric surgery (+0.80 [0.53, 1.07] and +0.40 [0.17, 0.62] m/s, respectively). Being non-diabetic and having larger decreases in post-surgery heart rate were independently associated with greater increases in post-surgical CAVI.

CONCLUSIONS

Arterial stiffness measures, CAVI and haPWV, were elevated after bariatric surgery despite other favorable cardiometabolic changes. Further studies are necessary to elucidate the underlying mechanism and prognostic implications of this elevation in arterial stiffness measures after bariatric surgery.

Effect of Bariatric Surgery on Serum Inflammatory Factors of Obese Patients: a Systematic Review and Meta-Analysis

Obesity is one of the main causes of inflammation. Previous studies have reported inconclusive results regarding the effect of bariatric surgery on inflammatory markers. This systematic review and meta-analysis is aimed at describing the effect of bariatric surgery on C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α). PubMed/Medline and Scopus were systematically searched for all eligible studies from inception to June 2018. Results are expressed as weighted mean difference (MD) with 95% confidence intervals (CI) using a random effects model. Overall, 116 studies which evaluated serum CRP, IL-6, and TNF-α after bariatric surgery were included. Pooled effect size showed significant reduction in serum CRP (- 5.30 mg/l, 95% CI - 5.46, - 5.15, P < 0.001), IL-6 (- 0.58 pg/ml, 95% CI - 0.64, - 0.53, P < 0.001), and TNF-α (- 0.20 pg/ml, 95% CI - 0.39, - 0.02, P = 0.031) with significant heterogeneity across studies (> 95% for all factors). Bariatric surgery significantly lowered inflammatory factors; however, baseline BMI, follow-up duration and type of surgery could impact the extent of observed effects.

iNOS as a metabolic enzyme under stress conditions

Nitric oxide (NO) is a free radical acting as a cellular signaling molecule in many different biochemical processes. NO is synthesized from l-arginine through the action of the nitric oxide synthase (NOS) family of enzymes, which includes three isoforms: endothelial NOS (eNOS), neuronal NOS (nNOS) and inducible NOS (iNOS). iNOS-derived NO has been associated with the pathogenesis and progression of several diseases, including liver diseases, insulin resistance, obesity and diseases of the cardiovascular system. However, transient NO production can modulate metabolism to survive and cope with stress conditions. Accumulating evidence strongly imply that iNOS-derived NO plays a central role in the regulation of several biochemical pathways and energy metabolism including glucose and lipid metabolism during inflammatory conditions. This review summarizes current evidence for the regulation of glucose and lipid metabolism by iNOS during inflammation, and argues for the role of iNOS as a metabolic enzyme in immune and non-immune cells.

Circulating markers of nitric oxide homeostasis and cardiometabolic diseases: insights from population-based studies

Emerging data suggest that impaired nitric oxide (NO) homeostasis has a key role in development of cardiometabolic disorders. The association between circulating levels of NO metabolites, i.e. nitrate and nitrite (NOx), and risk of chronic diseases has not yet been fully clarified. This work aims to address epidemiologic aspects of NO metabolism and discusses different physiologic and pathophysiologic conditions influencing circulating NOx. Further, cross-sectional associations of serum NOx with metabolic disorders are described and along the way, potential short-term and long-term power of serum NOx for predicting cardiometabolic outcomes are reviewed. Results from population-based studies show that circulating NOx is affected by aging, smoking habits, pregnancy, menopause status, thyroid hormones, and various pathologic conditions including type 2 diabetes, insulin resistance, hypertension, and renal dysfunction. Lifestyle factors, especially dietary habits, but also smoking habits and the degree of physical activity influence NO homeostasis and the circulating levels of NOx. Elevated serum NOx, due to increased iNOS activity, is associated with increased incidence of metabolic syndrome, different obesity phenotypes, and cardiovascular events.

Does Bariatric Surgery Improve Obesity Associated Comorbid Conditions

Obesity is a constantly growing health problem which reduces quality of life and life expectancy. Bariatric surgery for obesity is taken into account when all other conservative treatment modalities have failed. Comparison of the multidisciplinary programs with bariatric surgery regarding to weight loss showed that substantial and durable weight reduction have been achieved only with bariatric surgical treatments. However, the benefits of weight loss following bariatric procedures are still debated regarding the pro-inflammatory and metabolic profile of obesity.

Reduction of nitric oxide and DNA/RNA oxidation products are associated with active disease in systemic lupus erythematosus patients

The aims of the present study were to evaluate biomarkers of oxidative and nitrosative stress in systemic lupus erythematosus (SLE) patients, in particular products of DNA/RNA oxidative damage and their correlation with disease activity. This study included 188 controls and 203 patients; 153 with inactive SLE (SLEDAI < 6) and 50 with active SLE (SLEDAI ≥ 6) without renal impairment. Oxidative stress was assessed by tert-butyl hydroperoxide—initiated by chemiluminescence, advanced oxidation protein products (AOPP), total radical-trapping antioxidant parameter (TRAP), nitric oxide metabolites (NOx), and DNA/RNA oxidation products. Patients with SLE showed increased oxidative stress, as demonstrated by the augmentation of lipid hydroperoxides ( p < 0.0001) and AOPP ( p < 0.001) and reduced total antioxidant capacity ( p < 0.0001), without differences between patients with active disease and in remission. NOx levels and DNA/RNA oxidation products were inversely and independently associated with disease activity ( p < 0.0001 and p = 0.021, respectively), regardless of BMI and prednisone use. The linear regression analysis showed that about 5% of the SLEDAI score can be explained by the levels of DNA/RNA oxidation products ( r2:0.051; p = 0.002) and about 9% of this score by the levels of NOx ( r2:0.091; p < 0.0001). This study provides evidence for an inverse association between serum NOx levels and DNA/RNA oxidation products and SLE disease activity, suggesting that oxidative/nitrosative stress markers may be useful in evaluating SLE disease activity and progression of the disease.

Endothelial Dysfunction in Obesity

Chronic inflammatory state in obesity causes dysregulation of the endocrine and paracrine actions of adipocyte-derived factors, which disrupt vascular homeostasis and contribute to endothelial vasodilator dysfunction and subsequent hypertension. While normal healthy perivascular adipose tissue (PVAT) ensures the dilation of blood vessels, obesity-associated PVAT leads to a change in profile of the released adipo-cytokines, resulting in a decreased vasorelaxing effect. Adipose tissue inflammation, nitric oxide (NO)-bioavailability, insulin resistance and oxidized low-density lipoprotein (oxLDL) are main participating factors in endothelial dysfunction of obesity. In this chapter, disruption of inter-endothelial junctions between endothelial cells, significant increase in the production of reactive oxygen species (ROS), inflammation mediators, which are originated from inflamed endothelial cells, the balance between NO synthesis and ROS , insulin signaling and NO production, and decrease in L-arginine/endogenous asymmetric dimethyl-L-arginine (ADMA) ratio are discussed in connection with endothelial dysfunction in obesity.

Nitric oxide, oxidant status and antioxidant response in morbidly obese patients: the impact of 1-year surgical weight loss

BACKGROUND

The aims of this study were to evaluate nitric oxide (NO) metabolites (nitrite/nitrate NO x ) as proinflammatory parameter and total oxidant status (TOS) as well as total antioxidant response (TAR) as oxidative stress (OS) markers in morbidly obese (MO) patients in comparison with normal-weight healthy (NWH) subjects and to determine the post-bariatric surgery changes of NO x and OS indicators in relation with weight loss.

METHODS

We examined serum NO x , TOS, and TAR in a bariatric group of MO patients and a NWH control group (n = 23 each group). In the NWH group, serum was examined once, while in the MO group, serum was examined before and at 3, 6, and 12 months after silastic ring vertical gastroplasty (SRVG).

RESULTS

Serum NO x and TOS values were higher (p < 0.001), while TAR level was lower (p < 0.001) in MO patients as compared to the NWH group. No significant changes occurred at 12 months after surgery in the MO group as far as the NO x (p = 0.93), TOS (p = 0.11), and TAR (p = 0.15) levels were concerned as compared to baseline values. However, NO x increased at 6 months after surgery (p < 0.008) and then decreased by the 12th month after SRVG (p < 0.008), reaching almost baseline values.

CONCLUSIONS

At baseline, there was a high production of proinflammatory and OS markers in MO patients. SRVG surgical weight loss was not accompanied by significant changes of these parameters at 1 year after surgery.

Effect of bariatric surgery on cardiovascular risk profile

Obesity is associated with increased risk for cardiovascular (CV) disease (CVD) and CV mortality. Bariatric surgery has been shown to resolve or improve CVD risk factors, to varying degrees. The objective of this systematic review was to determine the impact of bariatric surgery on CV risk factors and mortality. A systematic review of the published research was performed to evaluate evidence regarding CV outcomes in morbidly obese bariatric patients. Two major databases (PubMed and the Cochrane Library) were searched. The review included all original reports reporting outcomes after bariatric surgery, published in English, from January 1950 to July 2010. In total, 637 studies were identified from the initial screen. After applying inclusion and exclusion criteria, 52 studies involving 16,867 patients were included (mean age 42 years, 78% women). The baseline prevalence of hypertension, diabetes, and dyslipidemia was 49%, 28%, and 46%, respectively. Mean follow-up was 34 months (range 3 to 155), and the average excess weight loss was 52% (range 16% to 87%). Most studies reported significant decreases postoperatively in the prevalence of CV risk factors, including hypertension, diabetes, and dyslipidemia. Mean systolic pressure reduced from to 139 to 124 mm Hg and diastolic pressure from 87 to 77 mm Hg. C-reactive protein decreased, endothelial function improved, and a 40% relative risk reduction for 10-year coronary heart disease risk was observed, as determined by the Framingham risk score. In conclusion, this review highlights the benefits of bariatric surgery in reducing or eliminating risk factors for CVD. It provides further evidence to support surgical treatment of obesity to achieve CVD risk reduction.

Effects of lifestyle measures, antiobesity agents, and bariatric surgery on serological markers of inflammation in obese patients

Overweight and obesity are highly prevalent in developed countries and are also becoming more frequent in the developing world. Overweight and obese patients have elevated levels of several inflammatory markers and this inflammatory state might contribute to their increased vascular risk. We summarize the effects of lifestyle changes, antiobesity agents, and bariatric surgery on serological inflammatory markers in overweight and obese patients. Most studies showed a decrease in inflammation with all 3 interventions. However, it remains to be established whether the decrease in inflammatory markers induced by lifestyle changes or (where indicated) with antiobesity agents or bariatric surgery will translate into reduced vascular morbidity and mortality in overweight and obese patients.

Increased serum nitric oxide concentration after bariatric surgery--a potential mechanism for cardiovascular benefit

BACKGROUND

It is believed that endothelial dysfunction associated with obesity contributes to reduced vascular production of nitric oxide (NO). Weight reduction after bariatric surgery is known to decrease the risk of cardiovascular disease. The purpose of this study was to determine whether bariatric surgery leads to improvement of metabolic markers of endothelial function: serum NO and its precursor (arginine) concentrations in obese patients.

METHODS

Serum NO and L-arginine concentrations were measured in 25 morbidly obese patients directly before and 6 months after bariatric surgery. Moreover, selected parameters that may be involved in development of endothelial dysfunction were also studied. Control group consisted of ten healthy individuals with normal body weight.

RESULTS

Six months after bariatric surgery, serum NO concentration was approximately 40% higher than before surgery. Surprisingly, serum NO concentration in nonobese controls was essentially similar to obese patients before surgery. In contrast, serum L-arginine concentration was higher in obese patients than in controls and decreased significantly after surgery. The body weight, blood pressure, triacylglycerols, LDL/HDL-cholesterol ratio, insulin, homeostasis model assessment score (HOMA-index), C-reactive protein, and white blood cell count were higher in obese patients as compared with controls and decreased significantly after surgery.

CONCLUSIONS

Our results indicate that improvement of insulin resistance, lipidemia, and blood pressure as well as reduction of systemic inflammation after bariatric surgery were associated with the increase of serum NO concentration. We propose that the increase in serum NO concentration contribute to diverse beneficial effects of weight loss after bariatric surgery especially in the context of risk of atherosclerosis.

Adaptation of Vasomotor Function of Human Coronary Arterioles to the Simultaneous Presence of Obesity and Hypertension

Objectives— We hypothesized that simultaneous presence of obesity and hypertension activates adaptive vascular mechanisms affecting dilations of human coronary arterioles.

Methods and Results— Agonist-induced dilations were assessed in isolated pressurized coronary arterioles from patients (n=38) who underwent cardiac surgery. Among normotensives we found that dilations to bradykinin (BK) and the NO-donor, sodium-nitroprusside (SNP) were reduced in obese subjects (BK, 10 −7 mol/L, lean:90±4%, obese:64±7%; SNP, 10 −6 mol/L, lean:89±7%, obese:76±5%). However, among hypertensives, both BK- and SNP-induced dilations were significantly enhanced in obese patients, when compared with lean individuals (BK, lean:71±7%, obese:85±3%; SNP, lean:60±6%, obese:83±2%). Correspondingly, in hypertensive patients, but not in those of normotensives, a positive correlation was found between body mass index (BMI) and BK-induced ( P =0.036, r =0.46), and also SNP-evoked ( P =0.031, r =0.44) coronary dilations. Moreover, in additional 55 hypertensive patients flow-mediated (FMD) and nitroglycerin (NTG)-induced dilations of the brachial artery were assessed. In obese hypertensive individuals, FMD- and NTG-induced dilations were greater (FMD:6.2±0.7%, NTG:17.2±0.9%), than in lean hypertensive patients (FMD:3.7±0.6%, NTG:13.6±1.1%). Correspondingly, FMD- and NTG-induced dilations were positively correlated with BMI ( P =0.020, r =0.31 and P =0.033, r =0.29, respectively).

Conclusions— These findings are the first to suggest that obesity may lead to activation of adaptive vascular mechanisms to enhance the dilator function of coronary and peripheral arterial vessels in hypertensive patients.