Characterization of the effect of serum bilirubin concentrations on coronary endothelial function via measurement of high-sensitivity C-reactive protein and high-density lipoprotein cholesterol

Predictors of left atrial remodeling in newly diagnosed hypertensive patients: a speckle-tracking echocardiographic study

Endothelial dysfunction, oxidative stress, and increased inflammatory activity are the main pathophysiological mechanisms responsible for cardiac remodeling secondary to hypertension. Bilirubin has anti-oxidant, anti-inflammatory, and anti-fibrotic functions. This report's objectives are to determine whether Query identifiers of left atrial (LA) remodeling, total atrial conduction time (TACT) and LA reservoir strain (LARS), are associated with serum total bilirubin levels, and to identify the possible predictors of LA remodeling in newly diagnosed hypertensive subjects. One hundred thirty-four subjects were enrolled in this study. TACT was evaluated by tissue Doppler imaging, and LARS was calculated by speckle-tracking echocardiography. Laboratory parameters were recorded. The subjects were classified into two separate groups according to the median value of TACT and LARS. In patients with supramedian TACT, LA volume index (LAVI) and epicardial adipose tissue (EAT) thickness were higher, while LARS and LVGLS were lower. In subjects with inframedian LARS, TACT was longer, LAVI and EAT thickness were higher, and LVGLS was lower. Patients with supramedian TACT and inframedian LARS were older and had lower total bilirubin. Total bilirubin, EAT thickness, and age were predictors of TACT and LARS. Serum bilirubin levels may have a protective effect on the LA remodeling process in newly diagnosed hypertensive subjects.

Bilirubin and Endothelial Function

Bilirubin is a fundamental metabolic end product of heme degradation. Despite acting as a cytotoxic metabolite at high concentrations, bilirubin at physiological concentrations has antioxidant effects, such as scavenging reactive oxygen species, leading to a decrease in oxidative stress. Endothelial dysfunction is an early feature of and plays an important role in the development and progression of atherosclerosis, leading to cardiovascular complications. One mechanism of endothelial dysfunction is an increase in oxidative stress, by which the bioavailability of nitric oxide is decreased. Therefore, bilirubin is expected to improve endothelial function, to inhibit the progression of atherosclerosis, and to reduce cardiovascular complications by inactivating oxidative stress through its antioxidant effects. In this review, we will focus on the clinical associations of the antioxidant bilirubin with endothelial function and cardiovascular complications.

The associations between serum biomarkers and stenosis of the coronary arteries

Serum biochemical indices reflect dynamic physiological and pathophysiological processes within the body, the associations between these markers and the number of stenotic coronary arteries have been rarely studied. 627 healthy controls and 1,049 coronary heart disease (CHD) patients were sequentially recruited in our hospital. The association patterns between serum biochemical markers and the numbers of stenotic coronary arteries were evaluated in a cross-sectional manner. Upon binary multiple logistic regression analysis, the risk factor patterns differed by gender. Age, high-density lipoprotein cholesterol (HDL) and homocysteine (HCY) were common risk factors for CHD in both males and females. Upon ordinal multiple logistic regression analysis, age, low-density lipoprotein cholesterol (LDL) and lipoprotein (Lp) (a) increased, and HDL decreased, as the number of stenotic coronary arteries increased in male patients. Age and Lp(a) were positively associated with the number of stenotic coronary arteries and total bilirubin (TBil) was negatively associated with the number of stenotic coronary arteries in female patients. Age and Lp(a) were common risk factors positively associated with the number of stenotic coronary arteries in both male and female patients. HDL and LDL were male-specific risk factors and TBil was a female-specific risk factor for an increasing number of stenotic coronary arteries. In conclusion, serum biomarker levels correlated with the number of stenotic coronary arteries and showed gender different patterns.

A Pilot Metabolic Profiling Study of Patients With Neonatal Jaundice and Response to Phototherapy

Phototherapy has been widely used in treating neonatal jaundice, but detailed metabonomic profiles of neonatal jaundice patients and response to phototherapy have not been characterized. Our aim was to depict the serum metabolic characteristics of neonatal jaundice patients relative to controls and changes in response to phototherapy. A (1) H nuclear magnetic resonance (NMR)-based metabonomic approach was employed to study the metabolic profiling of serum from healthy infants (n = 25) and from infants with neonatal jaundice (n = 30) pre- and postphototherapy. The acquired data were processed by multivariate principal component analysis (PCA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA). The PLS-DA and OPLS-DA model identified nine metabolites capable of distinguishing patients from controls. In addition, 28 metabolites such as β-glucose, α-glucose, valine, and pyruvate changed in response to phototherapy. This study offers useful information on metabolic disorders in neonatal jaundice patients and the effects of phototherapy on lipids, amino acid, and energy metabolism.

The pharmacological features of bilirubin: the question of the century

This review looks at the toxicity and metabolism of bilirubin in terms of its pharmacological potential. Its role has gained importance as more research has revealed the functional significance and interrelationship between the gasotransmitters nitric oxide and carbon monoxide. The biological actions of bilirubin have mostly been characterized in the high micromolar range where toxic effects occur. However, it could also prove to be an important cytoprotector for brain tissue, which is inherently less equipped for antioxidant defense. Plasma bilirubin levels negatively correlate to a number of disease states. Higher levels of bilirubin that are still within the normal range provide a protective effect to the body. The effects on various disorders could be tested using controlled pharmacological upregulation of the molecule with animal models. At nanomolar concentrations, considerable benefits have been obtained when the molecule was delivered pharmacologically under in vitro or in vivo test conditions, particularly in neurodegenerative disorders and after tissue or organ transplantation. The induction of heme oxygenase-1 (HMOX-1) via the activation of nuclear factor erythroid 2-related factor or the use of bile pigments in the harvesting of diseased tissue are novel applications, and like every new therapy, should be used with caution. HMOX-1 is tissue specific, and in exceptional states, such as schizophrenia and specific types of renal disorder, the same therapy may have disastrous effects.

Circulating bilirubin and defense against kidney disease and cardiovascular mortality: mechanisms contributing to protection in clinical investigations

Unconjugated bilirubin is an endogenous circulating antioxidant, bound to albumin, and therefore is retained in the vascular compartment. Bilirubin has well-documented neurotoxic effects in infants; however, current evidence indicates mildly elevated bilirubin is associated with protection from cardiovascular disease and all-cause mortality in adults. Recent clinical studies show mildly elevated bilirubin is associated with protection from kidney damage and dysfunction, in addition to cardiovascular events and all-cause mortality in patients undergoing hemodialysis. This is the first review to examine the clinical evidence and summarize the potential mechanisms of action that link bilirubin to protection from kidney damage, subsequent kidney failure, and dialysis-related mortality. With this understanding, it is hoped that new therapies will be developed to prevent renal dysfunction and mortality from cardiovascular disease in at-risk individuals.

Bilirubin increases insulin sensitivity in leptin-receptor deficient and diet-induced obese mice through suppression of ER stress and chronic inflammation

Obesity-induced endoplasmic reticulum (ER) stress causes chronic inflammation in adipose tissue and steatosis in the liver, and eventually leads to insulin resistance and type 2 diabetes (T2D). The goal of this study was to understand the mechanisms by which administration of bilirubin, a powerful antioxidant, reduces hyperglycemia and ameliorates obesity in leptin-receptor-deficient (db/db) and diet-induced obese (DIO) mouse models. db/db or DIO mice were injected with bilirubin or vehicle ip. Blood glucose and body weight were measured. Activation of insulin-signaling pathways, expression of inflammatory cytokines, and ER stress markers were measured in skeletal muscle, adipose tissue, and liver of mice. Bilirubin administration significantly reduced hyperglycemia and increased insulin sensitivity in db/db mice. Bilirubin treatment increased protein kinase B (PKB/Akt) phosphorylation in skeletal muscle and suppressed expression of ER stress markers, including the 78-kDa glucose-regulated protein (GRP78), CCAAT/enhancer-binding protein (C/EBP) homologous protein, X box binding protein (XBP-1), and activating transcription factor 4 in db/db mice. In DIO mice, bilirubin treatment significantly reduced body weight and increased insulin sensitivity. Moreover, bilirubin suppressed macrophage infiltration and proinflammatory cytokine expression, including TNF-α, IL-1β, and monocyte chemoattractant protein-1, in adipose tissue. In liver and adipose tissue of DIO mice, bilirubin ameliorated hepatic steatosis and reduced expression of GRP78 and C/EBP homologous protein. These results demonstrate that bilirubin administration improves hyperglycemia and obesity by increasing insulin sensitivity in both genetically engineered and DIO mice models. Bilirubin or bilirubin-increasing drugs might be useful as an insulin sensitizer for the treatment of obesity-induced insulin resistance and type 2 diabetes based on its profound anti-ER stress and antiinflammatory properties.

Protective effects of chronic resveratrol treatment on vascular inflammatory injury in streptozotocin-induced type 2 diabetic rats: Role of NF-kappa B signaling

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of macrovascular disease. Epidemiological studies suggest that plant polyphenol resveratrol (REV) is associated with reduced risk of cardiovascular diseases. Since chronic inflammatory and endothelial cell activation play a critical role in vascular aging and atherogenesis, we evaluated whether REV can inhibit inflammatory-induced vascular injury in T2DM. We found that REV (50mg/kg/d) can regulate glucose and lipid metabolism, improve insulin resistance and vascular permeability, and protect against the foam cells and cholesterol crystals formation in arterial vessel walls of T2DM rats. The protective effects of REV were consistent with the decrease in nuclear translocation of nuclear factor kappa B (NF-kappa B) and the downregulation of interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) levers in blood and tumor necrosis factor-alpha (TNF-α), intercellular adhesion molecule-1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) expressions in vascular wall. In addition, REV (10 and 100nmol/L) treatment protected cultured endothelial cells against increases in the expression of TNF-α, ICAM-1, and MCP-1 mRNA and protein induced by high glucose via inhibiting nuclear translocation of NF-kappa B p65. The specific NF-kappa B inhibitor pyrrolidine dithiocarbamate- (PDTC-) or small interfering RNA directed against NF-kappa B p65-mediated downregulation of NF-kappa B p65 was further enhanced by REV (100nmol/L) in the human endothelial cell line EA. hy926. In conclusion, these observations suggest that chronic treatment of T2DM rats with REV attenuates the inflammatory injury of the vascular wall and the effects are associated with down-regulation of the NF-kappa B signal pathway.

Serum Bilirubin Level and Aortic Intima–Media Thickness in Patients Without Clinical Manifestation of Atherosclerotic Cardiovascular Disease

We investigated the association between serum bilirubin level and thoracic aortic intima–media thickness (IMT). The study population consisted of 417 patients without coronary artery disease, who underwent transesophageal echocardiography examination for various indications. The highest aortic IMT values were observed in the bilirubinlow group compared with the bilirubinhigh group ( P < .001). Serum bilirubin level was associated with high-density lipoprotein cholesterol level ( r = .162, P = .001), high-sensitivity C-reactive protein (hsCRP; r = −.265, P < .001), and aortic IMT ( r = −.551, P < .001) in bivariate analysis. Multivariate linear regression analysis showed that serum bilirubin level was independently and negatively associated with hsCRP (β = −.095, P = .028) and aortic IMT (β = −.513, P < .001). Serum bilirubin level may be an independent predictor of the extent of subclinical aortic atherosclerosis assessed by thoracic aortic IMT.

Prognostic value of total bilirubin in patients with ST-segment elevation acute myocardial infarction undergoing primary coronary intervention

Previous studies have shown that the serum total bilirubin (TB) concentration was inversely related with stable coronary artery disease, diabetes mellitus, hypertension, and metabolic syndromes. The relation between TB levels and in-hospital and long-term outcomes in patients with ST-segment elevation myocardial infarction (STEMI) who undergo primary percutaneous coronary intervention (PCI) is not known. Data from 1,624 consecutive patients with STEMI who underwent primary PCI were evaluated. TB was measured after primary PCI, and the study population was divided into tertiles. The high TB group (n = 450) was defined as a value in the upper third tertile (>0.9 mg/dl) and the low TB group (n = 1,174) as any value in the lower 2 tertiles (≤0.9 mg/dl). The in-hospital mortality rate was significantly greater in the high TB group than in the low TB group (4% vs 1.5%, p = 0.003). In the multivariate analyses, a significant association was noted between high TB levels and the adjusted risk of in-hospital cardiovascular mortality (odds ratio 3.24, 95% confidence interval 1.27 to 8.27, p = 0.014). In the receiver operating characteristic curve analysis, TB >0.90 mg/dl was identified as an effective cutpoint in patients with STEMI for in-hospital cardiovascular mortality (area under the curve 0.66, 95% confidence interval 0.55 to 0.76, p = 0.001). The mean follow-up period was 26.2 months. No differences were seen in the long-term mortality rates between the 2 groups. In conclusion, high TB is independently associated with in-hospital adverse outcomes in patients with STEMI who undergo primary PCI. However, no association was found with long-term mortality.