A New Look at Novel Cardiovascular Risk Biomarkers: The Role of Atherogenic Lipoproteins and Innovative Antidiabetic Therapies

Evaluation of measured and calculated small dense low-density lipoprotein in capillary blood and association with the metabolic syndrome

BACKGROUND AND AIMS

Small-dense-low-density-lipoprotein cholesterol (sdLDL-C) is proatherogenic and not commonly measured. The aims were to evaluate capillary blood and its stability for sdLDL-C measurement and measure sdLDL-C in patients with metabolic syndrome (MS).

METHODS

182 patients were studied (49 with MS). sdLDL-C was measured by electrophoresis (LipoPrint®), direct measurement (Roche Diagnostics) and Sampson equation. Intima-media thickness (IMT) and presence of atheroma was evaluated. sdLDL-C was compared in paired venous and capillary blood according to CLSI-EP09c (n = 40). sdLDL-C stability was studied after 24 h at room temperature (RT).

RESULTS

sdLDL-C in capillary blood and venous blood showed agreement with the direct measurement (bias: 4.17 mg/dL, LOA 95 %:-5.66; 13.99) and estimation (bias:8.12 mg/dL, LOA 95 %:-8.59; 24.82). sdLDL-C is stable in capillary blood for 24 h at RT. The electrophoretic method yielded lower (p < 0.05) sdLDL-C than the equation or direct measurement. Patients with MS had (p < 0.05) higher sdLDL-C (%) than patients without MS. Patients with atheroma plaques had higher sdLDL-C (p < 0.05). Estimated sdLDL-C correlated with IMT (r = 0.259, p < 0.001).

CONCLUSIONS

Capillary blood is an alternative to venous blood for sdLDL-C measurement and is stable for 24 h after collection. Estimated and directly measured sdLDL-C associate with the MS being accessible tools for cardiovascular risk assessment.

Unique Metabolomic and Lipidomic Profile in Serum From Patients With Crohn's Disease and Ulcerative Colitis Compared With Healthy Control Individuals

BACKGROUND

Accurate biomarkers for disease activity and progression in patients with inflammatory bowel disease (IBD) are a prerequisite for individual disease characterization and personalized therapy. We show that metabolic profiling of serum from IBD patients is a promising approach to establish biomarkers. The aim of this work was to characterize metabolomic and lipidomic serum profiles of IBD patients in order to identify metabolic fingerprints unique to the disease.

METHODS

Serum samples were obtained from 55 patients with Crohn's disease (CD), 34 patients with ulcerative colitis (UC), and 40 healthy control (HC) individuals and analyzed using proton nuclear magnetic resonance spectroscopy. Classification of patients and HC individuals was achieved by orthogonal partial least squares discriminant analysis and univariate analysis approaches. Disease activity was assessed using the Gastrointestinal Symptom Rating Scale.

RESULTS

Serum metabolome significantly differed between CD patients, UC patients, and HC individuals. The metabolomic differences of UC and CD patients compared with HC individuals were more pronounced than the differences between UC and CD patients. Differences in serum levels of pyruvic acid, histidine, and the branched-chain amino acids leucine and valine were detected. The size of low-density lipoprotein particles shifted from large to small dense particles in patients with CD. Of note, apolipoprotein A1 and A2 serum levels were decreased in CD and UC patients with higher fecal calprotectin levels. The Gastrointestinal Symptom Rating Scale is negatively associated with the concentration of apolipoprotein A2.

CONCLUSIONS

Metabolomic assessment of serum samples facilitated the differentiation of IBD patients and HC individuals. These differences were constituted by changes in amino acid and lipoprotein levels. Furthermore, disease activity in IBD patients was associated with decreased levels of the atheroprotective apolipoproteins A1 and A2.

Oxidative Stress, Atherogenic Dyslipidemia, and Cardiovascular Risk

Oxidative stress is the consequence of an overproduction of reactive oxygen species (ROS) that exceeds the antioxidant defense mechanisms. Increased levels of ROS contribute to the development of cardiovascular disorders through oxidative damage to macromolecules, particularly by oxidation of plasma lipoproteins. One of the most prominent features of atherogenic dyslipidemia is plasma accumulation of small dense LDL (sdLDL) particles, characterized by an increased susceptibility to oxidation. Indeed, a considerable and diverse body of evidence from animal models and epidemiological studies was generated supporting oxidative modification of sdLDL particles as the earliest event in atherogenesis. Lipid peroxidation of LDL particles results in the formation of various bioactive species that contribute to the atherosclerotic process through different pathophysiological mechanisms, including foam cell formation, direct detrimental effects, and receptor-mediated activation of pro-inflammatory signaling pathways. In this paper, we will discuss recent data on the pathophysiological role of oxidative stress and atherogenic dyslipidemia and their interplay in the development of atherosclerosis. In addition, a special focus will be placed on the clinical applicability of novel, promising biomarkers of these processes.

Obesity and Dyslipidemia: A Review of Current Evidence

PURPOSE OF REVIEW

Obesity is accompanied by atherogenic dyslipidemia, a specific lipid disorder characterized by both quantitative and qualitative changes of plasma lipoproteins. The main alterations in the lipid profile include hypertriglyceridemia, reduced high-density lipoprotein (HDL) cholesterol level, and elevated small dense low-density lipoprotein (LDL) particles. Epidemiological data show that obesity is more common in women and is a frequent risk factor for reproductive disorders, metabolic complications in pregnancy, and cardiometabolic disease later in life. The aim of this narrative review is to discuss recent advances in the research of dyslipidemia in obesity, with an emphasis on female-specific disorders and cardiometabolic risk.

RECENT FINDINGS

The focus of current research on dyslipidemia in obesity is moving toward structurally and functionally modified plasma lipoproteins. Special attention is paid to the pro-atherogenic role of triglyceride-rich lipoproteins and their remnants. Introduction of advanced analytical techniques enabled identification of novel lipid biomarkers with potential clinical applications. In particular, proteomic and lipidomic studies have provided significant progress in the comprehensive research of HDL's alterations in obesity. Obesity-related dyslipidemia is a widespread metabolic disturbance in polycystic ovary syndrome patients and high-risk pregnancies, but is seldom evaluated with respect to its impact on future cardiometabolic health. Obesity and associated cardiometabolic diseases require a more depth insight into the quality of lipoprotein particles. Further application of omics-based techniques would enable a more comprehensive evaluation of dyslipidemia in order to reduce an excessive cardiovascular risk attributable to increased body weight. However, more studies on obesity-related female reproductive disorders are needed for this approach to be adopted in daily clinical practice.

The role of atherogenic lipoproteins in diabetes: Molecular aspects and clinical significance

Dyslipidaemia plays a prominent role in the genesis of atherosclerotic plaque and the increased cardiovascular risk in diabetes. Macrophages readily take up atherogenic lipoproteins, transforming into foam cells and amplifying vascular damage in the presence of endothelial dysfunction. We discuss the importance of distinct lipoprotein subclasses in atherogenic diabetic dyslipidaemia as well as the effects of novel anti-diabetic agents on lipoprotein fractions and ultimately on cardiovascular risk prevention. In patients with diabetes, lipid abnormalities should be aggressively identified and treated in conjunction with therapeutical agents used to prevent cardiovascular disease. The use of drugs that improve diabetic dyslipidaemia plays a prominent role in conferring cardiovascular benefit in individuals with diabetes.

Plasma Lipoprotein(a) Levels in Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis

INTRODUCTION

The polycystic ovary syndrome (PCOS) may represent an important model of lipid alterations. Lipoprotein(a) [Lp(a)] has emerged as a new marker of cardiovascular risk.

AIM

The main objective of this meta-analysis was to analyze the available evidence on Lp(a) levels in patients with PCOS compared to a control group.

METHODS

This meta-analysis was performed according to PRISMA guidelines. A literature search was performed to detect studies that have quantified Lp(a) levels in women with PCOS compared to a control group. The primary outcome was Lp(a) levels expressed in mg/dL. Random effects models were used.

RESULTS

Twenty-three observational studies including 2,337 patients were identified and considered eligible for this meta-analysis. In the overall analysis, the quantitative analysis showed that patients with PCOS have a higher Lp(a) levels (SMD: 1.1 [95% CI: 0.7 to 1.4]; I²=93%) compared to the control group. The results were similar in the analysis of the subgroups of patients according to body mass index (normal weight group: SMD: 1.2 [95% CI: 0.5 to 1.9], I²=95%; overweight group: SMD: 1.2 [95% CI: 0.5 to 1.8], I²=89%). Sensitivity analysis showed that the results were robust.

CONCLUSIONS

This meta-analysis shows that women with PCOS had higher levels of Lp(a) compared to healthy women used as a control group. These findings were observed in both overweight and non-overweight women.

Serum lipoprotein(a) predicts 1-year major cardiovascular events in patients after percutaneous coronary intervention

BACKGROUND

Lipoprotein(a) [Lp(a)], which is predictive of coronary heart disease (CHD), plays an important role in the pathogenesis of atherosclerosis. This study aimed to evaluate the association of Lp(a) with major adverse cardiovascular events (MACEs) and readmission in individuals who had undergone a percutaneous coronary intervention (PCI).

METHODS

A total of 1,938 patients with CHD who had undergone a PCI from January 2010 to December 2018 were assigned to three groups based on Lp(a) level. Follow-up was performed to assess the 1-year occurrence of MACEs and readmission.

RESULTS

Kaplan-Meier survival curves showed that the cumulative hazard incidence rate of MACEs and repeat PCI (re-PCI) significantly increased with Lp(a) level. Multivariate Cox proportional hazards regression analysis further confirmed Lp(a) as a significant independent predictor of MACEs. The area under the curve of the complex index risk score was significantly larger than those of other independent indicators. In individuals with low-density lipoprotein-cholesterol (LDL-C) levels either below 70 mg/dL or between 70 mg/dL and 100 mg/dL, Lp(a) was associated with increased rates of MACEs and readmission. In addition, a nomogram was constructed to predict 1-year MACE.

CONCLUSIONS

High Lp(a) levels may be a residual risk factor for MACEs in individuals with LDL-C levels under 100 mg/dL. Additionally, the built nomogram could predict 1-year MACEs with high accuracy. Lp(a) independently predicts 1-year MACEs, indicating its importance in risk assessment and the selection of clinical strategies in patients who have undergone a PCI.

The Role of Advanced Glycation End Products on Dyslipidemia

Disorders of lipoprotein metabolism and glucose homeostasis are common consequences of insulin resistance and usually co-segregate in patients with metabolic syndrome and type 2 diabetes mellitus (DM). Insulin-resistant subjects are characterized by atherogenic dyslipidemia, a specific lipid pattern which includes hypertriglyceridemia, reduced high-density lipoprotein cholesterol level, and increased proportion of small, dense low-density lipoprotein (LDL). Chronic hyperglycemia favors the processes of non-enzymatic glycation, leading to the increased production of advanced glycation end products (AGEs). Apart from direct harmful effects, AGEs are also potent inducers of oxidative stress and inflammation. In addition, increased AGEs' production may induce further qualitative modifications of small, dense LDL particles, converting them to glycated LDLs. These particles are even more atherogenic and may confer an increased cardiovascular risk. In this narrative review, we summarize the available evidence of the pathophysiological role and clinical importance of circulating AGEs and glycated LDLs in patients with dyslipidemia, particularly those with DM and related complications. In addition, we discuss recent advances and the issues that should be improved regarding laboratory assessment of AGEs and glycated LDLs, as well as the possibilities for their therapeutic modulation.

Oxidative Stress and Inflammatory Biomarkers in Patients with Diabetic Foot

Background and Objectives: Diabetic foot (DF) development is driven by complex interactions of hyperglycemia, inflammation, and oxidative stress (OS). We aimed to investigate OS and inflammatory biomarkers in patients with DF and their potential to improve early diagnosis and management of DF. Materials and Methods: The prooxidant−antioxidant balance (PAB), superoxide dismutase (SOD), total oxidative status (TOS), total sulfhydryl groups (SHG), routine biochemical parameters, and complete blood count were determined in 42 patients with type-2 DM, of which 23 patients had DF, while 19 patients were without DF complications. The neutrophils-to-lymphocyte ratio (NLR) was evaluated as a biomarker of inflammation. Results: Patients with DF had significantly higher (p < 0.05) PAB levels (170 ± 33.9 U/L) compared to those without DF complications (142 ± 31.3 U/L). In addition, patients with DF had significantly reduced SOD activities (p < 0.01). NLR values were significantly higher in the DF group (median: 2.8; interquartile range: 2.0−4.3) than in the group without DF (median: 1.4; interquartile range: 1.4−2.1; p < 0.01). A positive correlation was found between the PAB and NLR index (r = 0.449; p < 0.05). The diagnostic accuracy of both PAB (AUC = 0.741; p < 0.01) and NLR (AUC = 0.760; p < 0.01) was estimated as acceptable. Conclusions: In conclusion, the development of DF is associated with enhanced OS and inflammation processes. PAB and NLR could be useful non-invasive biomarkers of DF development.

Alteration in Redox Status and Lipoprotein Profile in COVID-19 Patients with Mild, Moderate, and Severe Pneumonia

BACKGROUND

Metabolic alterations, particularly disorders of lipoprotein metabolism in COVID-19, may affect the course and outcome of the disease. This study aims at evaluating the lipoprotein profile and redox status in SARS-CoV-2 infected patients with different pneumonia severity and their association with lethal outcomes.

METHODS

The prospective cohort study was performed on 98 COVID-19 patients with mild, moderate, and severe pneumonia. Lipid and inflammatory parameters, lipoprotein subclasses, and redox status biomarkers were determined at the study entry and after one week.

RESULTS

Compared to patients with mild and moderate pneumonia, severely ill patients had higher oxidised low-density lipoprotein (oxLDL) and malondialdehyde levels and lower high-density lipoprotein cholesterol (HDL-C) concentrations and paraoxonase 1 activity. Reduction in the proportion of large HDL 2a subclasses with a concomitant increase in the proportion of smallest HDL 3c and small dense LDL (sdLDL) particles was observed in patients with severe disease during the time. However, these changes were reversed in the mild and moderate groups. The results showed a positive association between changes in oxLDL and total antioxidative status. However, prooxidants and antioxidants in plasma were lower in patients with lethal outcomes.

CONCLUSIONS

Increased levels of oxLDL and sdLDL particles may contribute to the severity of COVID-19. The role of oxidative stress should be clarified in further studies, mainly its association with lethal outcomes.

Effects of Gestational Diabetes Mellitus on Cholesterol Metabolism in Women with High-Risk Pregnancies: Possible Implications for Neonatal Outcome

Metabolic disorders in pregnancy, particularly gestational diabetes mellitus (GDM), are associated with an increased risk for adverse pregnancy outcome and long-term cardiometabolic health of mother and child. This study analyzed changes of serum cholesterol synthesis and absorption markers during the course of high-risk pregnancies, with respect to the development of GDM. Possible associations of maternal lipid biomarkers with neonatal characteristics were also investigated. The study included 63 women with high risk for development of pregnancy complications. Size and proportions of small low-density (LDL) and high-density lipoprotein (HDL) particles were assessed across trimesters (T1−T3), as well as concentrations of cholesterol synthesis (lathosterol, desmosterol) and absorption markers (campesterol, β-sitosterol). During the study, 15 women developed GDM, while 48 had no complications (non-GDM). As compared to the non-GDM group, women with GDM had significantly higher triglycerides in each trimester, while having a lower HDL-C level in T3. In addition, they had significantly lower levels of β-sitosterol in T3 (p < 0.05). Cholesterol synthesis markers increased across trimesters in both groups. A decrease in serum β-sitosterol levels during the course of pregnancies affected by GDM was observed. The prevalence of small-sized HDL decreased in non-GDM, while in the GDM group remained unchanged across trimesters. Newborn’s size in the non-GDM group was significantly higher (p < 0.01) and inversely associated with proportions of both small, dense LDL and HDL particles (p < 0.05) in maternal plasma in T1. In conclusion, high-risk pregnancies affected by GDM are characterized by altered cholesterol absorption and HDL maturation. Advanced lipid testing may indicate disturbed lipid homeostasis in GDM.

Sorting through the extensive and confusing roles of sortilin in metabolic disease

Sortilin is a post-Golgi trafficking receptor homologous to the yeast vacuolar protein sorting receptor 10 (VPS10). The VPS10 motif on sortilin is a 10-bladed β-propeller structure capable of binding more than 50 proteins, covering a wide range of biological functions including lipid and lipoprotein metabolism, neuronal growth and death, inflammation, and lysosomal degradation. Sortilin has a complex cellular trafficking itinerary, where it functions as a receptor in the trans-Golgi network, endosomes, secretory vesicles, multivesicular bodies, and at the cell surface. In addition, sortilin is associated with hypercholesterolemia, Alzheimer's disease, prion diseases, Parkinson's disease, and inflammation syndromes. The 1p13.3 locus containing SORT1, the gene encoding sortilin, carries the strongest association with LDL-C of all loci in human genome-wide association studies. However, the mechanism by which sortilin influences LDL-C is unclear. Here, we review the role sortilin plays in cardiovascular and metabolic diseases and describe in detail the large and often contradictory literature on the role of sortilin in the regulation of LDL-C levels.

A Potential Interplay between HDLs and Adiponectin in Promoting Endothelial Dysfunction in Obesity

Obesity is an epidemic public health problem that has progressively worsened in recent decades and is associated with low-grade chronic inflammation (LGCI) in metabolic tissues and an increased risk of several diseases. In particular, LGCI alters metabolism and increases cardiovascular risk by impairing endothelial function and altering the functions of adiponectin and high-density lipoproteins (HDLs). Adiponectin is an adipokine involved in regulating energy metabolism and body composition. Serum adiponectin levels are reduced in obese individuals and negatively correlate with chronic sub-clinical inflammatory markers. HDLs are a heterogeneous and complex class of lipoproteins that can be dysfunctional in obesity. Adiponectin and HDLs are strictly interdependent, and the maintenance of their interplay is essential for vascular function. Since such a complex network of interactions is still overlooked in clinical settings, this review aims to highlight the mechanisms involved in the impairment of the HDLs/adiponectin axis in obese patients to predict the risk of cardiovascular diseases and activate preventive countermeasures. Here, we provide a narrative review of the role of LGCI in altering HDLs, adiponectin and endothelial functions in obesity to encourage new studies about their synergic effects on cardiovascular health and disease.

Extracellular Vesicles as an Index for Endothelial Injury and Cardiac Dysfunction in a Rodent Model of GDM

Gestational diabetes mellitus (GDM) increases risk of adverse pregnancy outcomes and maternal cardiovascular complications. It is widely believed that maternal endothelial dysfunction is a critical determinant of these risks, however, connections to maternal cardiac dysfunction and mechanisms of pathogenesis are unclear. Circulating extracellular vesicles (EVs) are emerging biomarkers that may provide insights into the pathogenesis of GDM. We examined the impact of GDM on maternal cardiac and vascular health in a rat model of diet-induced obesity-associated GDM. We observed a >3-fold increase in circulating levels of endothelial EVs (p < 0.01) and von Willebrand factor (p < 0.001) in GDM rats. A significant increase in mitochondrial DNA (mtDNA) within circulating extracellular vesicles was also observed suggesting possible mitochondrial dysfunction in the vasculature. This was supported by nicotinamide adenine dinucleotide deficiency in aortas of GDM mice. GDM was also associated with cardiac remodeling (increased LV mass) and a marked impairment in maternal diastolic function (increased isovolumetric relaxation time [IVRT], p < 0.01). Finally, we observed a strong positive correlation between endothelial EV levels and IVRT (r = 0.57, p < 0.05). In summary, we observed maternal vascular and cardiac dysfunction in rodent GDM accompanied by increased circulating endothelial EVs and EV-associated mitochondrial DNA. Our study highlights a novel method for assessment of vascular injury in GDM and highlights vascular mitochondrial injury as a possible therapeutic target.

Cholesterol Metabolic Markers for Differential Evaluation of Patients with Hyperlipidemia and Familial Hypercholesterolemia

The cholesterol metabolism in humans can be indirectly reflected by measuring cholesterol metabolism marker levels. We aimed to investigate the association of cholesterol homeostasis markers on standard lipid profiling components in familial hypercholesteremia and hyperlipidemia patients. A total of 69 hyperlipidemia patients, 25 familial hypercholesteremia (FHC) patients, and 64 healthy controls were enrolled in this study. We performed routine testing of blood lipid water. Gas chromatography was used to determine the changes in the concentration of cholesterol synthesis (squalene, desmosterol, and lathosterol) and absorption markers (campesterol, sitosterol, and stigmasterol) in the blood. Baseline hyperlipidemia patients displayed significantly higher total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) levels in comparison to the control group, which was reflected in the increased levels of squalene, desmosterol, campesterol, and sitosterol observed (P < 0.05) in the hyperlipidemia patients. The desmosterol, lathosterol, campesterol, stigmasterol, and sitosterol were statistically different in the FHC group than the hyperlipidemic group (P < 0.05). The proportions of squalene/cholesterol, lathosterol/cholesterol, stigmasterol/cholesterol, and sitosterol/cholesterol in the FHC group were lower than those in the hyperlipidemic group; only desmosterol/cholesterol was higher than that in the hyperlipidemic group. Correlation studies between lipid metabolic factors showed that the proportion of moderate and strong correlations was much higher in the FHC group than in the other two groups (76.92% vs. 32.50% and 31.25%). Logistic regression analysis showed that the concentrations of glucose, LDL-C, lactosterol, and sitosterol were all independent risk factors for developing hyperlipidemia. This result was further confirmed by the ROC curve. These results indicated that the study of cholesterol synthesis and decomposition markers can serve as a reference index for related diseases caused by changes in its concentration.

Glucagon-Like Peptide-1 Receptor Agonists and Dual Glucose-Dependent Insulinotropic Polypeptide/Glucagon-Like Peptide-1 Receptor Agonists in the Treatment of Obesity/Metabolic Syndrome, Prediabetes/Diabetes and Non-Alcoholic Fatty Liver Disease-Current Evidence

The obesity pandemic is accompanied by increased risk of developing metabolic syndrome (MetS) and related conditions: non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH), type 2 diabetes mellitus (T2DM) and cardiovascular (CV) disease (CVD). Lifestyle, as well as an imbalance of energy intake/expenditure, genetic predisposition, and epigenetics could lead to a dysmetabolic milieu, which is the cornerstone for the development of cardiometabolic complications. Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) and dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RAs promote positive effects on most components of the "cardiometabolic continuum" and consequently help reduce the need for polypharmacy. In this review, we highlight the main pathophysiological mechanisms and risk factors (RFs), that could be controlled by GLP-1 and dual GIP/GLP-1 RAs independently or through synergism or differences in their mode of action. We also address the evidence on the use of GLP-1 and dual GIP/GLP-1 RAs in the treatment of obesity, MetS and its related conditions (prediabetes, T2DM and NAFLD/NASH). In conclusion, GLP-1 RAs have already been established for the treatment of T2DM, obesity and cardioprotection in T2DM patients, while dual GIP/GLP-1 RAs appear to have the potential to possibly surpass them for the same indications. However, their use in the prevention of T2DM and the treatment of complex cardiometabolic metabolic diseases, such as NAFLD/NASH or other metabolic disorders, would benefit from more evidence and a thorough clinical patient-centered approach. There is a need to identify those patients in whom the metabolic component predominates, and whether the benefits outweigh any potential harm.

Biomarkers of dyslipidemia in patients with diabetic foot

Diabetic foot (DF) is one of the most severe complications of diabetes that significantly reduces the quality of life and survival of patients. Besides firmly established risk factors, novel data indicate that alterations in lipid metabolism might also be implicated in the development and progression of DF. Diabetic dyslipidemia is characterized by the atherogenic triad, consisting of increased triglycerides (TG), decreased high-density lipoprotein cholesterol (HDL-C) levels and the presence of small, dense low-density lipoprotein (LDL) particles. Accumulating evidence suggests that profound hypertriglyceridemia and HDL-C reduction are common findings in patients with diabetic neuropathy and significantly contribute to an increased risk for DF, amputation and mortality. Small, dense LDL particles play an important role in the development of cardiovascular complications of diabetes, but their clinical importance in patients with DF remains to be established. In this paper, we will discuss the significance of standard and novel lipid biomarker determination in the assessment of the risk for the development and progression of DF.