Understanding high-density lipoprotein function in disease: recent advances in proteomics unravel the complexity of its composition and biology

Advance in Multi-omics Research Strategies on Cholesterol Metabolism in Psoriasis

The skin is a complex and dynamic organ where homeostasis is maintained through the intricate interplay between the immune system and metabolism, particularly cholesterol metabolism. Various factors such as cytokines, inflammatory mediators, cholesterol metabolites, and metabolic enzymes play crucial roles in facilitating these interactions. Dysregulation of this delicate balance contributes to the pathogenic pathways of inflammatory skin conditions, notably psoriasis. In this article, we provide an overview of omics biomarkers associated with psoriasis in relation to cholesterol metabolism. We explore multi-omics approaches that reveal the communication between immunometabolism and psoriatic inflammation. Additionally, we summarize the use of multi-omics strategies to uncover the complexities of multifactorial and heterogeneous inflammatory diseases. Finally, we highlight potential future perspectives related to targeted drug therapies and research areas that can advance precise medicine. This review aims to serve as a valuable resource for those investigating the role of cholesterol metabolism in psoriasis.

The alveolar-capillary unit in the physiopathological conditions of heart failure: identification of a potential marker

In this review, we describe the structure and function of the alveolar-capillary membrane and the identification of a novel potential marker of its integrity in the context of heart failure (HF). The alveolar-capillary membrane is indeed a crucial structure for the maintenance of the lung parenchyma gas exchange capacity, and the occurrence of pathological conditions determining lung fluids accumulation, such as HF, might significantly impair lung diffusion capacity altering the alveolar-capillary membrane protective functions. In the years, we found that the presence of immature forms of the surfactant protein-type B (proSP-B) in the circulation reflects alterations in the alveolar-capillary membrane integrity. We discussed our main achievements showing that proSP-B, due to its chemical properties, specifically binds to high-density lipoprotein, impairing their antioxidant activity, and likely contributing to the progression of the disease. Further, we found that immature proSP-B, not the mature protein, is related to lung abnormalities, more precisely than the lung function parameters. Thus, to the list of the potential proposed markers of HF, we add proSP-B, which represents a precise marker of alveolar-capillary membrane dysfunction in HF, correlates with prognosis, and represents a precocious marker of drug therapy.

Association between psoriasis and serum apolipoprotein A1 and B: A systematic review and meta-analysis

Background

Psoriasis has been linked to dyslipidemia. However, the magnitude of the association between psoriasis and serum apolipoproteins A1 and B remains unclear.

Methods

We systematically searched PubMed, Embase, and Cochrane Library databases for eligible studies published before August 10, 2023. Data were pooled using Stata software. We adopted a random-effects model for the meta-analysis. Additionally, we conducted subgroup analyses of the studies according to the psoriasis type and matched body mass index (BMI).

Results

Seventeen studies involving 2467 participants were included. Psoriasis was associated with decreased serum apolipoprotein A1 (weighted mean difference [WMD] = -9.05, P < 0.001) and increased serum apolipoprotein B (WMD = 11.68, P < 0.001). In subgroup analysis after matching BMI, the findings showing an association of psoriasis with serum apolipoprotein A1 (WMD = -14.07, P < 0.001) and serum apolipoprotein B (WMD = 13.07, P < 0.001) were consistent with the overall results. The subgroup analysis for the presence or absence of psoriatic arthritis showed that serum apolipoprotein A1 was significantly decreased in psoriasis with (WMD = -11.29, P < 0.001) and without arthritis (WMD = -8.69, P = 0.039); whereas serum apolipoprotein B was significantly increased in psoriasis with (WMD = 13.57, P < 0.001) and without arthritis (WMD = 9.21, P < 0.001).

Conclusions

Our study revealed that psoriasis is associated with decreased serum apolipoprotein A1 and increased serum apolipoprotein B levels compared with healthy controls.

Relationship between High-density Lipoprotein Cholesterol and Insulin Resistance in Non-diabetic Chronic Kidney Disease Patients

Insulin resistance is linked to cardiovascular disease (CVD), even in non-diabetic patients. Therefore, insulin resistance contributes to the development of CVDs, which are the most important cause of morbidity and mortality in chronic kidney disease (CKD) and patients receiving dialysis replacement therapy. Furthermore, CKD greatly affects the enzyme activities responsible for the metabolism of high-density lipoprotein (HDL), causing an abnormal composition and function of HDL, which results in the loss of the anti-inflammatory effect of HDL and its protective effect against CVD. The study aimed to find the relationship between HDL-C, inflammation, and insulin resistance in nondiabetic CKD patients undergoing different modalities of treatment. This prospective cross-sectional comparative study included 80 subjects divided into the control group (20 healthy participants), Group 1 (15 predialysis CKD patients on conservative treatment), Group 2 (10 peritoneal dialysis patients), and Group 3 (35 hemodialysis patients). A full history, medical examination, and a laboratory investigation were carried out on all subjects from June 2018 to June 2019. The patient groups had significantly lower HDL and higher serum insulin than the control group. HDL was negatively correlated with the Homeostatic Model Assessment of Insulin Resistance. There was a strong negative association between HDL and insulin resistance in CKD patients. Therefore, lifestyle modifications and dyslipidemia treatment in CKD might help to prevent cardiovascular events even in nondiabetic nonobese CKD patients.

Paraoxonase-1: How a xenobiotic detoxifying enzyme has become an actor in the pathophysiology of infectious diseases and cancer

Both infectious and non-infectious diseases can share common molecular mechanisms, including oxidative stress and inflammation. External factors, such as bacterial or viral infections, excessive calorie intake, inadequate nutrients, or environmental factors, can cause metabolic disorders, resulting in an imbalance between free radical production and natural antioxidant systems. These factors may lead to the production of free radicals that can oxidize lipids, proteins, and nucleic acids, causing metabolic alterations that influence the pathogenesis of the disease. The relationship between oxidation and inflammation is crucial, as they both contribute to the development of cellular pathology. Paraoxonase 1 (PON1) is a vital enzyme in regulating these processes. PON1 is an enzyme that is bound to high-density lipoproteins and protects the organism against oxidative stress and toxic substances. It breaks down lipid peroxides in lipoproteins and cells, enhances the protection of high-density lipoproteins against different infectious agents, and is a critical component of the innate immune system. Impaired PON1 function can affect cellular homeostasis pathways and cause metabolically driven chronic inflammatory states. Therefore, understanding these relationships can help to improve treatments and identify new therapeutic targets. This review also examines the advantages and disadvantages of measuring serum PON1 levels in clinical settings, providing insight into the potential clinical use of this enzyme.

Crosstalk between high-density lipoproteins and endothelial cells in health and disease: Insights into sex-dependent modulation

Atherosclerotic cardiovascular disease is the leading cause of death worldwide. Intense research in vascular biology has advanced our knowledge of molecular mechanisms of its onset and progression until complications; however, several aspects of the patho-physiology of atherosclerosis remain to be further elucidated. Endothelial cell homeostasis is fundamental to prevent atherosclerosis as the appearance of endothelial cell dysfunction is considered the first pro-atherosclerotic vascular modification. Physiologically, high density lipoproteins (HDLs) exert protective actions for vessels and in particular for ECs. Indeed, HDLs promote endothelial-dependent vasorelaxation, contribute to the regulation of vascular lipid metabolism, and have immune-modulatory, anti-inflammatory and anti-oxidative properties. Sex- and gender-dependent differences are increasingly recognized as important, although not fully elucidated, factors in cardiovascular health and disease patho-physiology. In this review, we highlight the importance of sex hormones and sex-specific gene expression in the regulation of HDL and EC cross-talk and their contribution to cardiovascular disease.

Lipoprotein Assessment in the twenty-first Century

Based on decades of both basic science and epidemiologic research, there is overwhelming evidence for the causal relationship between high levels of cholesterol, especially low-density lipoprotein cholesterol and cardiovascular disease. Risk evaluation and monitoring the response to lipid-lowering therapies are heavily dependent on the accurate assessment of plasma lipoproteins in the clinical laboratory. This article provides an update of lipoprotein metabolism as it relates to atherosclerosis and how diagnostic measures of lipids and lipoproteins can serve as markers of cardiovascular risk, with a focus on recent advances in cardiovascular risk marker testing.

Dengue virus NS1 protein conveys pro-inflammatory signals by docking onto high-density lipoproteins

The dengue virus nonstructural protein 1 (NS1) is a secreted virulence factor that modulates complement, activates immune cells and alters endothelial barriers. The molecular basis of these events remains incompletely understood. Here we describe a functional high affinity complex formed between NS1 and human high-density lipoproteins (HDL). Collapse of the soluble NS1 hexamer upon binding to the lipoprotein particle leads to the anchoring of amphipathic NS1 dimeric subunits into the HDL outer layer. The stable complex can be visualized by electron microscopy as a spherical HDL with rod-shaped NS1 dimers protruding from the surface. We further show that the assembly of NS1-HDL complexes triggers the production of pro-inflammatory cytokines in human primary macrophages while NS1 or HDL alone do not. Finally, we detect NS1 in complex with HDL and low-density lipoprotein (LDL) particles in the plasma of hospitalized dengue patients and observe NS1-apolipoprotein E-positive complexes accumulating overtime. The functional reprogramming of endogenous lipoprotein particles by NS1 as a means to exacerbate systemic inflammation during viral infection provides a new paradigm in dengue pathogenesis.

Higher Free Triiodothyronine Is Associated With Higher HDL Particle Concentration and Smaller HDL Particle Size

CONTEXT

Thyroid function status has effects on the development of atherosclerotic cardiovascular disease by affecting lipid metabolism, but associations of high-density lipoprotein (HDL) particle concentrations and subfractions with thyroid hormone levels within the reference range remain elusive.

OBJECTIVE

The aim of the present study was to determine the associations of free triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) levels with HDL particle characteristics in euthyroid individuals.

METHODS

This cross-sectional study on the associations of thyroid hormones with HDL particle concentrations, HDL subfractions, and HDL particle size included 5844 euthyroid individuals (FT3, FT4, and TSH levels within the reference range and no medication use affecting thyroid function), participating in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study. HDL particles and subfractions were measured by nuclear magnetic resonance using an optimized version of the NMR LipoProfile Test (LP4).

RESULTS

In multivariable linear regression analyses, FT3 was positively associated with total HDL particle concentration (std.β = 0.14; P < 0.001) and with small (std.β = 0.13; P < 0.001) and medium-sized HDL particles (std.β = 0.05; P = 0.001). Conversely, FT3 was inversely associated with large HDL particles (std.β = -0.07; P < 0.001) and with HDL particle size (std.β = -0.08; P < 0.001). Such associations with FT4 or reciprocally with TSH were less pronounced or nonsignificant.

CONCLUSION

In euthyroid individuals, higher FT3 is cross-sectionally associated with higher total HDL particle concentration and with lower HDL particle size. These associations may be relevant to better understand the role of HDL in thyroid function-associated atherosclerotic cardiovascular disease.

Role of High-Density Lipoprotein Cholesterol (HDL-C) as a Clinical Predictor of Decompensation in Patients with Chronic Liver Disease (CLD)

INTRODUCTION

Systemic inflammation triggered by bacterial products like lipopolysaccharides (LPS) in the circulation is an important factor leading to decompensation in patients with chronic liver disease (CLD). High-density lipoprotein cholesterol (HDL-C) has a significant role in innate immune response to LPS in the circulation and could therefore increase the risk for decompensation in patients with CLD. In this study, we have explored the role of HDL-C as a prognostic marker for decompensation.

METHODS

This was a prospective, observational, cohort study where consecutive patients with CLD were included. Patients with cholestatic liver disease and hepatocellular carcinoma were excluded. Fasting lipids were measured in all patients at the time of recruitment. Each patient was carefully followed up for development of decompensation events such as new-onset/worsening ascites, hepatic encephalopathy, or variceal bleed during follow-up.

RESULTS

A total of 170 patients were included (mean age 60 ± 11.5 years, M : F = 6 : 1). At the end of follow-up, 97/170 patients (57%) had decompensation events. Mean HDL-C levels were significantly lower among patients with decompensation (27.5 ± 15 mg/dL vs. 43.5 ± 13.9 mg/dL; p value 0.004). Using ROC analysis, cut-off for HDL-C of 36.4 mg/dL was identified. On multivariate analysis, HDL-C (OR = 6.072; 95% CI 2.39-15.39) was found to have an independent association with risk of decompensation.

CONCLUSIONS

HDL-C level (<36.4 mg/dL) is a reliable marker for risk of decompensation and can be a useful addition to existing prognostic scoring systems in CLD. It can be a valuable tool to streamline treatment protocols and prioritise liver transplantation.

Modification of High-Density Lipoprotein Functions by Diet and Other Lifestyle Changes: A Systematic Review of Randomized Controlled Trials

High-density lipoprotein (HDL) functional traits have emerged as relevant elements that may explain HDL antiatherogenic capacity better than HDL cholesterol levels. These properties have been improved in several lifestyle intervention trials. The aim of this systematic review is to summarize the results of such trials of the most commonly used dietary modifications (fatty acids, cholesterol, antioxidants, alcohol, and calorie restriction) and physical activity. Articles were screened from the Medline database until March 2021, and 118 randomized controlled trials were selected. Results from HDL functions and associated functional components were extracted, including cholesterol efflux capacity, cholesteryl ester transfer protein, lecithin-cholesterol acyltransferase, HDL antioxidant capacity, HDL oxidation status, paraoxonase-1 activity, HDL anti-inflammatory and endothelial protection capacity, HDL-associated phospholipase A2, HDL-associated serum amyloid A, and HDL-alpha-1-antitrypsin. In mainly short-term clinical trials, the consumption of monounsaturated and polyunsaturated fatty acids (particularly omega-3 in fish), and dietary antioxidants showed benefits to HDL functionality, especially in subjects with cardiovascular risk factors. In this regard, antioxidant-rich dietary patterns were able to improve HDL function in both healthy individuals and subjects at high cardiovascular risk. In addition, in randomized trial assays performed mainly in healthy individuals, reverse cholesterol transport with ethanol in moderate quantities enhanced HDL function. Nevertheless, the evidence summarized was of unclear quality and short-term nature and presented heterogeneity in lifestyle modifications, trial designs, and biochemical techniques for the assessment of HDL functions. Such findings should therefore be interpreted with caution. Large-scale, long-term, randomized, controlled trials in different populations and individuals with diverse pathologies are warranted.

HDL proteome remodeling associates with COVID-19 severity

Background

Besides the well-accepted role in lipid metabolism, high-density lipoprotein (HDL) also seems to participate in host immune response against infectious diseases.

Objective: We used a quantitative proteomic approach to test the hypothesis that alterations in HDL proteome associate with severity of Coronavirus disease 2019 (COVID-19).

Methods

Based on clinical criteria, subjects (n=41) diagnosed with COVID-19 were divided into two groups: a group of subjects presenting mild symptoms and a second group displaying severe symptoms and requiring hospitalization. Using a proteomic approach, we quantified the levels of 29 proteins in HDL particles derived from these subjects.

Results

We showed that the levels of serum amyloid A 1 and 2 (SAA1 and SAA2, respectively), pulmonary surfactant-associated protein B (SFTPB), apolipoprotein F (APOF), and inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4) were increased by more than 50% in hospitalized patients, independently of sex, HDL-C or triglycerides when comparing with subjects presenting only mild symptoms. Altered HDL proteins were able to classify COVID-19 subjects according to the severity of the disease (error rate 4.9%). Moreover, apolipoprotein M (APOM) in HDL was inversely associated with odds of death due to COVID-19 complications (odds ratio [OR] per 1-SD increase in APOM was 0.27, with 95% confidence interval [CI] of 0.07 to 0.72, P=0.007).

Conclusion

Our results point to a profound inflammatory remodeling of HDL proteome tracking with severity of COVID-19 infection. They also raise the possibility that HDL particles could play an important role in infectious diseases.

High-density lipoproteins (HDL): Novel function and therapeutic applications

The failure of high-density lipoprotein (HDL)-raising agents to reduce cardiovascular disease (CVD) together with recent findings of increased cardiovascular mortality in subjects with extremely high HDL-cholesterol levels provide new opportunities to revisit our view of HDL. The concept of HDL function developed to explain these contradictory findings has recently been expanded by a role played by HDL in the lipolysis of triglyceride-rich lipoproteins (TGRLs) by lipoprotein lipase. According to the reverse remnant-cholesterol transport (RRT) hypothesis, HDL critically contributes to TGRL lipolysis via acquirement of surface lipids, including free cholesterol, released from TGRL. Ensuing cholesterol transport to the liver with excretion into the bile may reduce cholesterol influx in the arterial wall by accelerating removal from circulation of atherogenic, cholesterol-rich TGRL remnants. Such novel function of HDL opens wide therapeutic applications to reduce CVD in statin-treated patients, which primarily involve activation of cholesterol flux upon lipolysis.

Anti-inflammatory HDL effects are impaired in atrial fibrillation

High-density lipoprotein (HDL), best known for cholesterol transport, also has anti-inflammatory effects. Previous studies suggest involvement of myeloperoxidase (MPO) in modification of HDL. HDL bound Sphingosine-1-phosphate (S1P) has been implied to be an essential protein regarding beneficial HDL effects. In this study, we analyzed anti-inflammatory HDL properties in patients with atrial fibrillation (AF), a disease involving atrial inflammation, compared to non-AF controls and whether anti-inflammatory properties improve upon catheter ablation. Additionally, association with serum concentrations of MPO and S1P were assessed. We isolated HDL from 25 AF patients, 13 non-AF individuals and 14 AF patients at follow-up (FU) after catheter ablation. S1P was measured in a cohort of 141 AF and 21 FU patients. Following preincubation with HDL from either group, bovine aortic endothelial cells were stimulated using tumor necrosis factor α and expression of pro-inflammatory genes intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), E-selectin (SELE) and P-selectin (SELP) was assessed using qPCR. Concentrations of circulating protein of these genes as well as MPO and S1P were measured in serum samples. Compared to non-AF individuals HDL from AF patients suppressed gene expression of the pro-inflammatory adhesion molecules ICAM1, VCAM1, SELE and SELP 27%, 18%, 21% and 57% less, respectively (p < 0.05 for all except SELE p = 0.06). In FU patients, the anti-inflammatory HDL activity was improved (suppression of ICAM1 + 22%, VCAM1 + 10%, SELE + 38% and SELP + 75%, p < 0.05 for all except VCAM1 p = 0.08). AF patients using angiotensin converting enzyme inhibitors or angiotensin receptor blockers had better anti-inflammatory HDL properties than non-users (gene expression suppression at least 28% more, p < 0.05 for all except ICAM1 p = 0.051). Circulating protein concentrations were not correlated with in vitro gene-expression, but circulating P-selectin was generally elevated in AF and FU patients compared to non-AF patients. MPO plasma concentration was positively associated with gene-expression of ICAM1, VCAM1 and SELP (r² > 0.4, p < 0.05). Serum concentrations of S1P were increased in FU patients {1.201 µM [1.077–1.543]} compared to AF patients {0.953 µM [0.807–1.135], p < 0.01} but not correlated with ICAM1, VCAM1 and SELP gene expression. We conclude that the anti-inflammatory activity of HDL is impaired in AF patients, which might promote AF progression and AF-associated complications.

On the Role of Paraoxonase-1 and Chemokine Ligand 2 (C-C motif) in Metabolic Alterations Linked to Inflammation and Disease. A 2021 Update

Infectious and many non-infectious diseases share common molecular mechanisms. Among them, oxidative stress and the subsequent inflammatory reaction are of particular note. Metabolic disorders induced by external agents, be they bacterial or viral pathogens, excessive calorie intake, poor-quality nutrients, or environmental factors produce an imbalance between the production of free radicals and endogenous antioxidant systems; the consequence being the oxidation of lipids, proteins, and nucleic acids. Oxidation and inflammation are closely related, and whether oxidative stress and inflammation represent the causes or consequences of cellular pathology, both produce metabolic alterations that influence the pathogenesis of the disease. In this review, we highlight two key molecules in the regulation of these processes: Paraoxonase-1 (PON1) and chemokine (C-C motif) ligand 2 (CCL2). PON1 is an enzyme bound to high-density lipoproteins. It breaks down lipid peroxides in lipoproteins and cells, participates in the protection conferred by HDL against different infectious agents, and is considered part of the innate immune system. With PON1 deficiency, CCL2 production increases, inducing migration and infiltration of immune cells in target tissues and disturbing normal metabolic function. This disruption involves pathways controlling cellular homeostasis as well as metabolically-driven chronic inflammatory states. Hence, an understanding of these relationships would help improve treatments and, as well, identify new therapeutic targets.

Subpopulations of High-Density Lipoprotein: Friends or Foes in Cardiovascular Disease Risk in Chronic Kidney Disease?

Dyslipidemia is a major traditional risk factor for cardiovascular disease (CVD) in chronic kidney disease (CKD) patients, although the altered lipid profile does not explain the number and severity of CVD events. High-density lipoprotein (HDL) is a heterogeneous (size, composition, and functionality) population of particles with different atherogenic or atheroprotective properties. HDL-cholesterol concentrations per se may not entirely reflect a beneficial or a risk profile for CVD. Large HDL in CKD patients may have a unique proteome and lipid composition, impairing their cholesterol efflux capacity. This lack of HDL functionality may contribute to the paradoxical coexistence of increased large HDL and enhanced risk for CVD events. Moreover, CKD is associated with inflammation, oxidative stress, diabetes, and/or hypertension that are able to interfere with the anti-inflammatory, antioxidative, and antithrombotic properties of HDL subpopulations. How these changes interfere with HDL functions in CKD is still poorly understood. Further studies are warranted to fully clarify if different HDL subpopulations present different functionalities and/or atheroprotective effects. To achieve this goal, the standardization of techniques would be valuable.

Immature Circulating SP-B, Bound to HDL, Represents an Early Sign of Smoke-Induced Pathophysiological Alterations

Cigarette smoking is a major independent risk factor for cardiovascular diseases (CVD). The underlying mechanisms, however, are not clearly understood. Lungs are the primary route of exposure to smoke, with pulmonary cells and surfactant being the first structures directly exposed, resulting in the leakage of the immature proteoform of surfactant protein B (proSP-B). Herein, we evaluated whether proSP-B joined the cargo of high-density lipoprotein (HDL) proteins in healthy young subjects (n = 106) without any CVD risk factor other than smoking, and if HDL-associated proSP-B (HDL-SPB) correlated with pulmonary function parameters, systemic inflammation, and oxidative stress. At univariable analysis, HDL-SPB resulted significantly higher in smokers (2.2-fold, p < 0.001) than in non-smokers. No significant differences have been detected between smokers and non-smokers for inflammation, oxidation variables, and alveolar-capillary diffusion markers. In a multivariable model, HDL-SPB was independently associated with smoking. In conclusion, HDL-SPB is not only a precocious and sensitive index of the acute effects of smoke, but it might be also a potential causal factor in the onset of the vascular damage induced by modified HDL. These findings contribute to the emerging concept that the quality of the HDL proteome, rather than the quantity of particles, plays a central role in CVD risk protection.

Obesity-Related Changes in High-Density Lipoprotein Metabolism and Function

In obese individuals, atherogenic dyslipidemia is a very common and important factor in the increased risk of cardiovascular disease. Adiposity-associated dyslipidemia is characterized by low high-density lipoprotein cholesterol (HDL-C) levels and an increase in triglyceride-rich lipoproteins. Several factors and mechanisms are involved in lowering HDL-C levels in the obese state and HDL quantity and quality is closely related to adiponectin levels and the bioactive lipid sphingosine-1-phosphate. Recent studies have shown that obesity profoundly alters HDL metabolism, resulting in altered HDL subclass distribution, composition, and function. Importantly, weight loss through gastric bypass surgery and Mediterranean diet, especially when enriched with virgin olive oil, is associated with increased HDL-C levels and significantly improved metrics of HDL function. A thorough understanding of the underlying mechanisms is crucial for a better understanding of the impact of obesity on lipoprotein metabolism and for the development of appropriate therapeutic approaches. The objective of this review article was to summarize the newly identified changes in the metabolism, composition, and function of HDL in obesity and to discuss possible pathophysiological consequences.

Arylesterase Activity of HDL Associated Paraoxonase as a Potential Prognostic Marker in Patients With Sepsis and Septic Shock-A Prospective Pilot Study

Background: High-density lipoprotein (HDL) plays an essential role in the immune system and shows effective antioxidative properties. We investigated correlations of lipid parameters with the sequential organ failure assessment (SOFA) score and the prognostic association with mortality in sepsis patients admitted to intensive care unit (ICU). Methods: We prospectively recruited consecutive adult patients with sepsis and septic shock, according to sepsis-3 criteria as well as non-sepsis ICU controls. Results: Fifty-three patients with sepsis (49% with septic shock) and 25 ICU controls without sepsis were enrolled. Dyslipidemia (HDL-C < 40 mg/l) was more common in sepsis compared to non-sepsis patients (85 vs. 52%, p = 0.002). Septic patients compared to controls had reduced HDL-C (14 vs. 39 mg/l, p < 0.0001), lower arylesterase activity of the antioxidative paraoxonase of HDL (AEA) (67 vs. 111 mM/min/ml serum, p < 0.0001), and a non-significant trend toward reduced cholesterol efflux capacity (9 vs. 10%, p = 0.091). We observed a strong association between higher AEA and lower risk of 28-day [per 10 mM/min/ml serum increase in AEA: odds ratio (OR) = 0.76; 95% CI, 0.61-0.94; p = 0.01) and ICU mortality (per 10 mM/min/ml serum increase in AEA: OR = 0.71, 95% CI, 0.56-0.90, p = 0.004) in the sepsis cohort in univariable logistic regression analysis. AEA was confirmed as an independent predictor of 28-day and ICU mortality in multivariable analyses. AEA discriminated well-regarding 28-day/ICU mortality in area under the receiver operating characteristic curve (AUROC) analyses. In survival analysis, 28-day mortality estimates were 40 and 69% with AEA ≥/< the 25th percentile of AEA's distribution, respectively (log-rank p = 0.0035). Conclusions: Both compositional and functional HDL parameters are profoundly altered during sepsis. In particular, the functionality parameter AEA shows promising prognostic potential in sepsis patients.

Cardioprotective Properties of HDL: Structural and Functional Considerations

BACKGROUND

As Mendelian Randomization (MR) studies showed no effect of variants altering HDL-cholesterol (HDL-C) levels concerning Cardiovascular Disease (CVD) and novel therapeutic interventions aiming to raise HDL-C resulted to futility, the usefulness of HDL-C is unclear.

OBJECTIVE

As the role of HDL-C is currently doubtful, it is suggested that the atheroprotective functions of HDLs can be attributed to the number of HDL particles, and their characteristics including their lipid and protein components. Scientific interest has focused on HDL function and on the causes of rendering HDL particles dysfunctional, whereas the relevance of HDL subclasses with CVD remains controversial.

METHODS

The present review discusses changes in quality as much as in quantity of HDL in pathological conditions and the connection between HDL particle concentration and cardiovascular disease and mortality. Emphasis is given to the recently available data concerning the cholesterol efflux capacity and the parameters that determine HDL functionality, as well as to recent investigations concerning the associations of HDL subclasses with cardiovascular mortality.

RESULTS

MR studies or pharmacological interventions targeting HDL-C are not in favor of the hypothesis of HDL-C levels and the relationship with CVD. The search of biomarkers that relate with HDL functionality is needed. Similarly, HDL particle size and number exhibit controversial data in the context of CVD and further studies are needed.

CONCLUSION

There is no room for the old concept of HDL as a silver bullet,as HDL-C cannot be considered a robust marker and does not reflect the importance of HDL particle size and number. Elucidation of the complex HDL system, as well as the finding of biomarkers, will allow the development of any HDL-targeted therapy.

Dietary sucrose induces metabolic inflammation and atherosclerotic cardiovascular diseases more than dietary fat in LDLr-/-ApoB100/100 mice

BACKGROUND AND AIMS

Poor dietary habits contribute to the obesity pandemic and related cardiovascular diseases but the respective impact of high saturated fat versus added sugar consumption remains debated. Herein, we aimed to disentangle the individual role of dietary fat versus sugar in cardiometabolic disease progression.

METHODS

We fed pro-atherogenic LDLr^-/-ApoB^100/100 mice either a low-fat/high-sucrose (LFHS) or a high-fat/low-sucrose (HFLS) diet for 24 weeks. Weekly body weight gain was registered. 16S rRNA gene-based gut microbial analysis was performed to investigate gut microbial modulations. Intraperitoneal insulin (ipITT) and oral glucose tolerance test (oGTT) were conducted to assess glucose homeostasis and insulin sensitivity. Cytokines were assessed in fasted plasma, epididymal white adipose tissue and liver lysates. Heart function was evaluated by echocardiography. Aortic atheroma lesions were quantified according to the en face technique.

RESULTS

HFLS feeding increased obesity, insulin resistance and dyslipidemia compared to LFHS feeding. Conversely, high sucrose consumption decreased gut microbial diversity while augmenting inflammation and the adaptative immune defense against metabolic endotoxemia and reduced macrophage cholesterol efflux capacity. This led to more severe cardiovascular complications as revealed by remarkably high level of atherosclerotic lesions and the early development of cardiac dysfunction in LFHS vs HFLS fed mice.

CONCLUSIONS

We uncoupled obesity-associated insulin resistance from cardiovascular diseases and provided novel evidence that dietary sucrose, not fat, is the main driver of metabolic inflammation accelerating severe atherosclerosis in hyperlipidemic mice.

Lipid efflux mechanisms, relation to disease and potential therapeutic aspects

Lipids are hydrophobic and amphiphilic molecules involved in diverse functions such as membrane structure, energy metabolism, immunity, and signaling. However, altered intra-cellular lipid levels or composition can lead to metabolic and inflammatory dysfunction, as well as lipotoxicity. Thus, intra-cellular lipid homeostasis is tightly regulated by multiple mechanisms. Since most peripheral cells do not catabolize cholesterol, efflux (extra-cellular transport) of cholesterol is vital for lipid homeostasis. Defective efflux contributes to atherosclerotic plaque development, impaired β-cell insulin secretion, and neuropathology. Of these, defective lipid efflux in macrophages in the arterial walls leading to foam cell and atherosclerotic plaque formation has been the most well studied, likely because a leading global cause of death is cardiovascular disease. Circulating high density lipoprotein particles play critical roles as acceptors of effluxed cellular lipids, suggesting their importance in disease etiology. We review here mechanisms and pathways that modulate lipid efflux, the role of lipid efflux in disease etiology, and therapeutic options aimed at modulating this critical process.

Roles of Reconstituted High-Density Lipoprotein Nanoparticles in Cardiovascular Disease: A New Paradigm for Drug Discovery

Epidemiological results revealed that there is an inverse correlation between high-density lipoprotein (HDL) cholesterol levels and risks of atherosclerotic cardiovascular disease (ASCVD). Mounting evidence supports that HDLs are atheroprotective, therefore, many therapeutic approaches have been developed to increase HDL cholesterol (HDL-C) levels. Nevertheless, HDL-raising therapies, such as cholesteryl ester transfer protein (CETP) inhibitors, failed to ameliorate cardiovascular outcomes in clinical trials, thereby casting doubt on the treatment of cardiovascular disease (CVD) by increasing HDL-C levels. Therefore, HDL-targeted interventional studies were shifted to increasing the number of HDL particles capable of promoting ATP-binding cassette transporter A1 (ABCA1)-mediated cholesterol efflux. One such approach was the development of reconstituted HDL (rHDL) particles that promote ABCA1-mediated cholesterol efflux from lipid-enriched macrophages. Here, we explore the manipulation of rHDL nanoparticles as a strategy for the treatment of CVD. In addition, we discuss technological capabilities and the challenge of relating preclinical in vivo mice research to clinical studies. Finally, by drawing lessons from developing rHDL nanoparticles, we also incorporate the viabilities and advantages of the development of a molecular imaging probe with HDL nanoparticles when applied to ASCVD, as well as gaps in technology and knowledge required for putting the HDL-targeted therapeutics into full gear.

The Role and Function of HDL in Patients with Chronic Kidney Disease and the Risk of Cardiovascular Disease

Chronic kidney disease (CKD) is a worldwide health problem with steadily increasing occurrence. Significantly elevated cardiovascular morbidity and mortality have been observed in CKD. Cardiovascular diseases are the most important and frequent cause of death of CKD patients globally. The presence of CKD is related to disturbances in lipoprotein metabolism whose consequences are dyslipidemia and the accumulation of atherogenic particles. CKD not only fuels the reduction of high-density lipoprotein (HDL) cholesterol concentration, but also it modifies the composition of this lipoprotein. The key role of HDL is the participation in reverse cholesterol transport from peripheral tissues to the liver. Moreover, HDL prevents the oxidation of low-density lipoprotein (LDL) cholesterol by reactive oxygen species (ROS) and protects against the adverse effects of oxidized LDL (ox-LDL) on the endothelium. Numerous studies have demonstrated the ability of HDL to promote the production of nitric oxide (NO) by endothelial cells (ECs) and to exert antiapoptotic and anti-inflammatory effects. Increasing evidence suggests that in patients with chronic inflammatory disorders, HDLs may lose important antiatherosclerotic properties and become dysfunctional. So far, no therapeutic strategy to raise HDL, or alter the ratio of HDL subfractions, has been successful in slowing the progression of CKD or reducing cardiovascular disease in patients either with or without CKD.

Recent Advances in the Critical Role of the Sterol Efflux Transporters ABCG5/G8 in Health and Disease

Cardiovascular disease is characterized by lipid accumulation, inflammatory response, cell death, and fibrosis in the arterial wall and is the leading cause of morbidity and mortality worldwide. Cholesterol gallstone disease is caused by complex genetic and environmental factors and is one of the most prevalent and costly digestive diseases in the USA and Europe. Although sitosterolemia is a rare inherited lipid storage disease, its genetic studies led to identification of the sterol efflux transporters ABCG5/G8 that are located on chromosome 2p21 in humans and chromosome 17 in mice. Human and animal studies have clearly demonstrated that ABCG5/G8 play a critical role in regulating hepatic secretion and intestinal absorption of cholesterol and plant sterols. Sitosterolemia is caused by a mutation in either the ABCG5 or the ABCG8 gene alone, but not in both simultaneously. Polymorphisms in the ABCG5/G8 genes are associated with abnormal plasma cholesterol metabolism and may play a key role in the genetic determination of plasma cholesterol concentrations. Moreover, ABCG5/G8 is a new gallstone gene, LITH9. Gallstone-associated variants in ABCG5/G8 are involved in the pathogenesis of cholesterol gallstones in European, Asian, and South American populations. In this chapter, we summarize the latest advances in the critical role of the sterol efflux transporters ABCG5/G8 in regulating hepatic secretion of biliary cholesterol, intestinal absorption of cholesterol and plant sterols, the classical reverse cholesterol transport, and the newly established transintestinal cholesterol excretion, as well as in the pathogenesis and pathophysiology of ABCG5/G8-related metabolic diseases such as sitosterolemia, cardiovascular disease, and cholesterol gallstone disease.

Lipidomic profiles of maternal blood at the earlier stage of gestation and umbilical venous blood in response to supraphysiological hypercholesterolemia versus physiological hypercholesterolemia: An evidence of potential biomarkers and early intervention

BACKGROUND

To our knowledge, we lack a complete understanding of the lipidomes alterations caused by maternal supraphysiological hypercholesterolemia (MSPH) at the third trimester.

OBJECTIVES

The aim of this study was to investigate lipidomes alterations in maternal and umbilical venous (UV) serum and explore the association between these alterations and MSPH.

METHODS

We conducted a nest case-control study between maternal physiological hypercholesterolemia (MPH) and MSPH subjects during pregnancy. Lipidomic profiling of maternal serum at the first trimester of gestation and UV serum was performed by ultra-high-performance liquid chromatography system connected to a quadrupole time-of-light/mass spectrometer.

RESULTS

Several glycerophospholipids and sphingolipids (C18 sphingoid base) species were distinctly altered in maternal serum and/or UV serum with MSPH versus MPH. Glycerophospholipid metabolism, sphingolipid metabolism and propanoate metabolism were the main pathways that involved the most of discriminate metabolites. Higher HDL-c and phosphatidylcholine (16:0/0:0) (PC (16:0/0:0)) during pregnancy, higher PC (16:0/0:0) and lower cholesterol ester 20:4(8Z,11Z,14Z,17Z) (CE (20:4(8Z,11Z,14Z,17Z))) in the UV serum may be the risk factors for the increased placental circulation resistance. The total cholesterol levels of maternal serum both at the first trimester and at the third trimester were significantly correlated with some lipid species of UV serum.

CONCLUSION

This study clarifies the differential lipid profiles to distinguish MSPH from MPH and the pathway which is influenced under the condition of MSPH. Also, it provides a resource to look for potential therapeutic targets for MSPH.

The impact of recent advances in lipidomics and redox lipidomics on dermatological research

Dermatological research is a major beneficiary of the rapidly developing advances in lipid analytic technology and of bioinformatic tools which help to decipher and interpret the accumulating big lipid data. At its interface with the environment, the epidermis develops a blend of lipids that constitutes the epidermal lipid barrier, essential for the protection from water loss and entry of dangerous noxae. Apart from their structural role in the barrier, novel intra- and inter-cellular signaling functions of lipids and their oxidation products have been uncovered in most cutaneous cell types over the last decades, and the discovery rate has been boosted by the advent of high resolution and -throughput mass spectrometric techniques. Our understanding of epidermal development has benefited from studies on fetal surface lipids, which appear to signal for adaptation to desiccation post partum, and from studies on the dynamics of epidermal lipids during adjustment to the atmosphere in the first months of life. At birth, external insults begin to challenge the skin and its lipids, and recent years have yielded ample insights into the dynamics of lipid synthesis and -oxdiation after UV exposure, and upon contact with sensitizers and irritants. Psoriasis and atopic dermatitis are the most common chronic inflammatory skin diseases, affecting at least 3% and 7% of the global population, respectively. Consequently, novel (redox-) lipidomic techniques have been applied to study systemic and topical lipid abnormalities in patient cohorts. These studies have refined the knowledge on eicosanoid signaling in both diseases, and have identified novel biomarkers and potential disease mediators, such as lipid antigens recognized by psoriatic T cells, as well as ceramide species, which specifically correlate with atopic dermatitis severity. Both biomarkers have yielded novel mechanistic insights. Finally, the technological progress has enabled studies to be performed that have monitored the consequences of diet, lifestyle, therapy and cosmetic intervention on the skin lipidome, highlighting the translational potential of (redox-) lipidomics in dermatology.

The Fluid Aspect of the Mediterranean Diet in the Prevention and Management of Cardiovascular Disease and Diabetes: The Role of Polyphenol Content in Moderate Consumption of Wine and Olive Oil

A growing interest has emerged in the beneficial effects of plant-based diets for the prevention of cardiovascular disease, diabetes and obesity. The Mediterranean diet, one of the most widely evaluated dietary patterns in scientific literature, includes in its nutrients two fluid foods: olive oil, as the main source of fats, and a low-to-moderate consumption of wine, mainly red, particularly during meals. Current mechanisms underlying the beneficial effects of the Mediterranean diet include a reduction in inflammatory and oxidative stress markers, improvement in lipid profile, insulin sensitivity and endothelial function, as well as antithrombotic properties. Most of these effects are attributable to bioactive ingredients including polyphenols, mono- and poly-unsaturated fatty acids. Polyphenols are a heterogeneous group of phytochemicals containing phenol rings. The principal classes of red wine polyphenols include flavonols (quercetin and myricetin), flavanols (catechin and epicatechin), anthocyanin and stilbenes (resveratrol). Olive oil has at least 30 phenolic compounds. Among them, the main are simple phenols (tyrosol and hydroxytyrosol), secoroids and lignans. The present narrative review focuses on phenols, part of red wine and virgin olive oil, discussing the evidence of their effects on lipids, blood pressure, atheromatous plaque and glucose metabolism.

Analysis of fatty acids in mouse tissue via in situ transmethylation with biochar

Lipid derivatization technology-mediated fatty acid profiling studies have been suggested to dissect the contents of lipids in white fat and brown fat tissue. The focus of this study is to profile fatty acid lipidomics in brown adipose tissue and white adipose tissue of mice by derivatizing their lipids into fatty acid methyl esters via in situ transmethylation using a rice husk-derived biochar as porous media. The in situ transmethylation using biochar is advantageous in biological analysis because there was no loss of samples inevitably occurring in the loss of lipid in solvent extraction and purification steps.

Comparison of Mechanisms of Endothelial Cell Protections Between High-Density Lipoprotein and Apolipoprotein A-I Mimetic Peptide

Apolipoprotein A-I (apoA-I) mimetic peptide, D-4F, exhibits anti-atherogenic effects similar to high-density lipoprotein (HDL). However, it remains elusive whether D-4F and HDL share similar molecular mechanisms underlying anti-atherogenic effects and endothelial cell protections. We here compared the metabolic changes in endothelial cells induced by D-4F and HDL against oxidized low-density lipoprotein (ox-LDL), which may be of benefit to understanding the protective mechanisms of HDL and D-4F. Functional assays, including wound healing, transwell migration, and tube formation, were used to evaluate the pro-angiogenic effects of HDL and D-4F. NMR-based metabolomic analysis was employed to explore the protective mechanisms underlying HDL and D-4F. Partial least-squares discriminant analysis (PLS-DA) was performed to assess metabolic profiles, and orthogonal PLS-DA (OPLS-DA) was carried out to identify characteristic metabolites. Moreover, significantly altered metabolic pathways were also analyzed. We found that ox-LDL impaired the migration and tube formation of endothelial cells. Metabolomic analysis showed that ox-LDL triggered oxidative stress, impaired glycolysis, and enhanced glycerophospholipid metabolism. Both HDL and D-4F improved the migration and angiogenesis of endothelial cells, alleviated oxidative stress, and ameliorated disordered glycolysis impaired by ox-LDL. Strikingly, HDL partially attenuated the disturbed glycerophospholipid metabolism, whereas D-4F did not show this effect. In summary, although D-4F shared the similar protective effects with HDL on the migration and angiogenesis of endothelial cells, it could not deduce the molecular mechanisms of HDL completely. Nevertheless, D-4F possesses the potentiality to be exploited as clinically applicable agent for endothelial cell protection and cardiovascular disease treatment.

Paraoxonase 1, HDL Subclasses and Post Surgery Acute Inflammation: A Pilot Study

High density lipoproteins (HDL) structure and function studies are needed to better understand the heterogeneous nature of the HDL particle, and its interaction with associated proteins such as apolipoprotein A-1 (ApoA-1), paraoxonase 1 (PON1) and the environment. Our study assesses the effects of acute inflammation on PON1 and HDL subclasses in post-surgical colorectal cancer patients. PON1 was measured kinetically through its arylesterase and lactonase activity and HDL sub-classes were measured using Quantimetrix Lipoprint^® System. White blood cells (WBC) counts, c-reactive protein (CRP) and serum amyloid A (SAA) levels were also analyzed using standard techniques. Our findings show that baseline PON1 activity is lower in colorectal cancer patients and significant reductions are observed in the acute inflammatory state post-surgery. PON1 changes are also inversely related to inflammatory markers such as SAA and CRP. In addition, our preliminary findings show that small and intermediate HDL decreases post-op Day 1. In conclusion, our study demonstrates the effects of chronic and acute inflammation on PON1. Specifically, PON1 arylesterase and lactonase activity is lower in states of chronic inflammation and further decreased in the acute inflammatory state. Additionally, in our limited sample size, while changes in PON1 and HDL subclasses may be variable in the acute inflammatory period, small HDL decreased with a loss of PON1 activity in the subacute phase.

Allergic rhinitis is associated with complex alterations in high-density lipoprotein composition and function

Despite strong evidence that high-density lipoproteins (HDLs) modulate the immune response, the role of HDL in allergies is still poorly understood. Many patients with allergic rhinitis (AR) develop a late-phase response, characterized by infiltration of monocytes and eosinophils into the nasal submucosa. Functional impairment of HDL in AR-patients may insufficiently suppress inflammation and cell infiltration, but the effect of AR on the composition and function of HDL is not understood. We used apolipoprotein (apo) B-depleted serum as well as isolated HDL from AR-patients (n = 43) and non-allergic healthy controls (n = 20) for detailed compositional and functional characterization of HDL. Both AR-HDL and apoB-depleted serum of AR-patients showed decreased anti-oxidative capacity and impaired ability to suppress monocyte nuclear factor-κB expression and pro-inflammatory cytokine secretion, such as interleukin (IL)-4, IL-6, IL-8, tumor necrosis factor alpha and IL-1 beta. Sera of AR-patients showed decreased paraoxonase and cholesteryl-ester transfer protein activities, increased lipoprotein-associated phospholipase A2 activity, while lecithin-cholesterol acyltransferase activity and cholesterol efflux capacity were not altered. Surprisingly, apoB-depleted serum and HDL from AR-patients showed an increased ability to suppress eosinophil effector responses upon eotaxin-2/CCL24 stimulation. Mass spectrometry and biochemical analyses showed reduced levels of apoA-I and phosphatidylcholine, but increased levels of apoA-II, triglycerides and lyso-phosphatidylcholine in AR-HDL. The changes in AR-HDL composition were associated with altered functional properties. In conclusion, AR alters HDL composition linked to decreased anti-oxidative and anti-inflammatory properties but improves the ability of HDL to suppress eosinophil effector responses.

Atrial fibrillation is associated with alterations in HDL function, metabolism, and particle number

Increased morbidity and mortality in atrial fibrillation (AF) are related to the pro-fibrotic, pro-thrombotic, and pro-inflammatory processes that underpin the disease. High-density lipoproteins (HDL) have anti-inflammatory, anti-oxidative, and anti-thrombotic properties. Functional impairment of HDL may, therefore, associate with AF initiation or progression. We studied indices of HDL quality and quantity of AF patients and healthy controls, including HDL-particle number, HDL cholesterol, apolipoprotein (apo) A-I levels, serum amyloid A (SAA) content and HDL-cholesterol efflux capacity, and paraoxonase activity of apoB-depleted serum. Serum samples were collected from AF patients (n = 91) before catheter ablation and from age- and sex-matched control subjects (n = 54). HDL-cholesterol efflux capacity was assessed in a validated assay using [³H]-cholesterol-labeled J774 macrophages. Lecithin-cholesterol acyltransferase (LCAT) and paraoxonase activities were assessed using fluorometric assays, SAA levels were determined by ELISA, and total and subclass HDL-particle number was assessed by nuclear magnetic resonance spectroscopy. ApoA-I levels were determined by immunoturbidimetry. HDL-cholesterol efflux capacity, HDL-particle number, apoA-I levels, and LCAT activity were markedly reduced in AF patients when compared to healthy individuals (all p < 0.001), whereas HDL-associated paraoxonase activity and SAA content were not altered (p = 0.578, p = 0.681). Notably, cholesterol efflux capacity, HDL-particle number, apoA-I levels as well as LCAT activity recovered following restoration of sinus rhythm (all p < 0.001). We identified marked alterations in HDL function, HDL maturation, and HDL-particle number in AF patients. Assessing HDL-particle number and function in AF may be used as a surrogate marker of AF onset and progression and may help identifying patients at high risk.

Proteomic alterations of HDL in youth with type 1 diabetes and their associations with glycemic control: a case-control study

Background

Patients with type 1 diabetes (T1DM) typically have normal or even elevated plasma high density lipoprotein (HDL) cholesterol concentrations; however, HDL protein composition can be altered without a change in cholesterol content. Alteration of the HDL proteome can result in dysfunctional HDL particles with reduced ability to protect against cardiovascular disease (CVD). The objective of this study was to compare the HDL proteomes of youth with T1DM and healthy controls (HC) and to evaluate the influence of glycemic control on HDL protein composition.

Methods

This was a cross-sectional case–control study. Blood samples were obtained from patients with T1DM and HC. HDL was isolated from plasma by size-exclusion chromatography and further purified using a lipid binding resin. The HDL proteome was analyzed by mass spectrometry using label-free SWATH peptide quantification.

Results

Samples from 26 patients with T1DM and 13 HC were analyzed and 78 HDL-bound proteins were measured. Youth with T1DM had significantly increased amounts of complement factor H related protein 2 (FHR2; adjusted P < 0.05), compared to HC. When patients were analyzed based on glucose control, several trends emerged. Some proteins were altered in T1DM and not influenced by glycemic control (e.g. FHR2) while others were partially or completely corrected with optimal glucose control (e.g. alpha-1-beta glycoprotein, A1BG). In a subgroup of poorly controlled T1DM patients, inter alpha trypsin inhibitor 4 (ITIH4) was dramatically elevated (P < 0.0001) and this was partially reversed in patients with optimal glucose control. Some proteins including complement component C3 (CO3) and albumin (ALB) were significantly different only in T1DM patients with optimal glucose control, suggesting a possible effect of exogenous insulin.

Conclusions

Youth with T1DM have proteomic alterations of their HDL compared to HC, despite similar concentration of HDL cholesterol. The influence of these compositional changes on HDL function are not yet known. Future efforts should focus on investigating the role of these HDL associated proteins in regard to HDL function and their role in CVD risk in patients with T1DM.

Trial registration NCT02275091

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0846-9) contains supplementary material, which is available to authorized users.

Immature surfactant protein-B impairs the antioxidant capacity of HDL

Circulating immature surfactant protein B (proSP-B) forms emerged as the most reliable lung-specific circulating marker for alveolar-capillary membrane (ACM) dysfunction and for the overall clinical status of heart failure (HF). Notably, in terms of HF hospitalization, immature SP-B overwhelms the prognostic role of other most frequently used clinical parameters such as those related to lung dysfunction. The strong prognostic value of circulating proSP-B in HF suggests more widespread and possible systemic effects. Thus, we assessed the plasma distribution of proSP-B evaluating whether it exists in a lipoprotein-bound form and its impact on lipoprotein structure and function. ProSP-B forms were detectable in high-density lipoprotein (HDL) only. To assess the impact of proSP-B on HDL, HDL from healthy subjects were enriched with proSP-B produced by a stably transfected CHO cell line that specifically expresses and releases the human proSP-B. After enrichment, HDL size and lipoprotein electrophoretic mobility, and protein composition did not show apparent differences. HDL antioxidant capacity (HOI), assessed as their ability to inhibit air-induced LDL oxidation, was impaired after proSP-B enrichment. HOI was also higher in HF patients with respect to age-matched control healthy subjects (p = 0.013). Circulating proSP-B, besides its potential role as a specific marker for ACM dysfunction in HF patients with diagnostic and prognostic value, binds to human HDL impairing their antioxidant capacity. These findings shed light on proSP-B as a molecule that contributes to the reduction of the defense against oxidative stress, a key mediator in the pathogenesis of HF.

LC-MS-Based Metabolomics and Lipidomics Study of High-Density-Lipoprotein-Modulated Glucose Metabolism with an apoA-I Knockout Mouse Model

Type 2 diabetes mellitus (T2DM) has become a tremendous problem in public health nowadays. High-density lipoprotein (HDL) refers to a group of heterogeneous particles that circulate in blood, and a recent research finds that HDL acts a pivotal part of glucose metabolism. To understand systemic metabolic changes correlated with HDL in glucose metabolism, we applied LC-MS-based metabolomics and lipidomics to detect metabolomic and lipidomic profiles of plasma from apoA-I knockout mice fed a high-fat diet. Multivariate analysis was applied to differentiate apoA-I knockout mice and controls, and potential biomarkers were found. Pathway analysis demonstrated that several metabolic pathways such as aminoacyl-tRNA biosynthesis, arginine and proline metabolism, and phenylalanine, tyrosine, and tryptophan biosynthesis were dysregulated in apoA-I knockout mice. This study may provide a new insight into the underlying pathogenesis in T2DM and prove that LC-MS-based metabolomics and lipidomics are powerful approaches in finding potential biomarkers and disturbed pathways.

HDL in Endocrine Carcinomas: Biomarker, Drug Carrier, and Potential Therapeutic

High-density lipoprotein (HDL) have long been studied for their protective role against cardiovascular diseases, however recently relationship between HDL and cancer came into focus. Several epidemiological studies have shown an inverse correlation between HDL-cholesterol (HDL-C) and cancer risk, and some have even implied that HDL-C can be used as a predictive measure for survival prognosis in for specific sub-population of certain types of cancer. HDL itself is an endogenous nanoparticle capable of removing excess cholesterol from the periphery and returning it to the liver for excretion. One of the main receptors for HDL, scavenger receptor type B-I (SR-BI), is highly upregulated in endocrine cancers, notably due to the high demand for cholesterol by cancer cells. Thus, the potential to exploit administration of cholesterol-free reconstituted or synthetic HDL (sHDL) to deplete cholesterol in endocrine cancer cell and stunt their growth of use chemotherapeutic drug loaded sHDL to target payload delivery to cancer cell has become increasingly attractive. This review focuses on the role of HDL and HDL-C in cancer and application of sHDLs as endocrine cancer therapeutics.

Which Lipids Should Be Analyzed for Diagnostic Workup and Follow-up of Patients with Hyperlipidemias?

PURPOSE OF REVIEW

To summarize and discuss the clinical use of lipid and apolipoprotein tests in the settings of diagnosis and therapeutic follow-up of hyperlipidemia.

RECENT FINDINGS

The joint consensus panel of the European Atherosclerosis Society (EAS) and the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) recently produced recommendations on the measurement of atherogenic lipoproteins, taking into account the strengths and weaknesses of analytical and clinical performances of the tests. Total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, and calculated non-HDL cholesterol (= LDL + remnant cholesterol) constitute the primary lipid panel for hyperlipidemia diagnosis and cardiovascular risk estimation. LDL cholesterol is the primary target of lipid-lowering therapies. Non-HDL cholesterol or apolipoprotein B should be used as secondary therapeutic target in patients with mild-to-moderate hypertriglyceridemia, 2-10 mmol/l (175-880 mg/dl). Lipoprotein (a) is included in LDL cholesterol and should be measured at least once in all patients at cardiovascular risk, including to explain poor response to statin treatment.

Cardiovascular Benefits of Phenol-Enriched Virgin Olive Oils: New Insights from the Virgin Olive Oil and HDL Functionality (VOHF) Study

SCOPE

The main findings of the "Virgin Olive Oil and HDL Functionality" (VOHF) study and other related studies on the effect of phenol-enriched virgin olive oil (VOO) supplementation on cardiovascular disease are integrated in the present work.

METHODS AND RESULTS

VOHF assessed whether VOOs, enriched with their own phenolic compounds (FVOO) or with those from thyme (FVOOT), improve quantity and functionality of HDL. In this randomized, double-blind, crossover, and controlled trial, 33 hypercholesterolemic subjects received a control VOO (80 mg kg-1 ), FVOO (500 mg kg-1 ), and FVOOT (500 mg kg-1 ; 1:1) for 3 weeks. Both functional VOOs promoted cardioprotective changes, modulating HDL proteome, increasing fat-soluble antioxidants, improving HDL subclasses distribution, reducing the lipoprotein insulin resistance index, increasing endogenous antioxidant enzymes, protecting DNA from oxidation, ameliorating endothelial function, and increasing fecal microbial metabolic activity. Additional cardioprotective benefits were observed according to phenol source and content in the phenol-enriched VOOs. These insights support the beneficial effects of OO and PC from different sources.

CONCLUSION

Novel therapeutic strategies should increase HDL-cholesterol levels and enhance HDL functionality. The tailoring of phenol-enriched VOOs is an interesting and useful strategy for enhancing the functional quality of HDL, and thus, it can be used as a complementary tool for the management of hypercholesterolemic individuals.

The Role of High-Density Lipoproteins in Diabetes and Its Vascular Complications

Almost 600 million people are predicted to have diabetes mellitus (DM) by 2035. Diabetic patients suffer from increased rates of microvascular and macrovascular complications, associated with dyslipidaemia, impaired angiogenic responses to ischaemia, accelerated atherosclerosis, and inflammation. Despite recent treatment advances, many diabetic patients remain refractory to current approaches, highlighting the need for alternative agents. There is emerging evidence that high-density lipoproteins (HDL) are able to rescue diabetes-related vascular complications through diverse mechanisms. Such protective functions of HDL, however, can be rendered dysfunctional within the pathological milieu of DM, triggering the development of vascular complications. HDL-modifying therapies remain controversial as many have had limited benefits on cardiovascular risk, although more recent trials are showing promise. This review will discuss the latest data from epidemiological, clinical, and pre-clinical studies demonstrating various roles for HDL in diabetes and its vascular complications that have the potential to facilitate its successful translation.

HDL functionality and cardiovascular outcome among nondialysis chronic kidney disease patients

CVD remains the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). CKD profoundly affects HDL composition and functionality, but whether abnormal HDL independently contributes to cardiovascular events in CKD patients remains elusive. In the present study, we assessed whether compositional and functional properties of HDL predict cardiovascular outcome among 526 nondialysis CKD patients who participate in the CARE FOR HOMe study. We measured HDL cholesterol, the content of HDL-associated proinflammatory serum amyloid A (SAA), and activities of the HDL enzymes paraoxonase and lipoprotein-associated phospholipase A2 (Lp-PLA₂). In addition, we assessed the antioxidative activity of apoB-depleted serum. During a mean follow-up of 5.1 ± 2.1 years, 153 patients reached the predefined primary endpoint, a composite of atherosclerotic cardiovascular events including cardiovascular mortality and death of any cause. In univariate Cox regression analyses, lower HDL-cholesterol levels, higher HDL-associated SAA content, and lower paraoxonase activity predicted cardiovascular outcome, while Lp-PLA₂ activity and antioxidative capacity did not. HDL-cholesterol and HDL-paraoxonase activity lost their association with cardiovascular outcome after adjustment for traditional cardiovascular and renal risk factors, while SAA lost its association after further adjustment for C-reactive protein. In conclusion, our data suggest that neither HDL quantity nor HDL composition or function independently predict cardiovascular outcome among nondialysis CKD patients.

Cholesterol and Lipoprotein Metabolism and Atherosclerosis: Recent Advances In reverse Cholesterol Transport

Atherosclerosis is characterized by lipid accumulation, inflammatory response, cell death and fibrosis in the arterial wall, and is major pathological basis for ischemic coronary heart disease (CHD), which is the leading cause of morbidity and mortality in the USA and Europe. Intervention studies with statins have shown to reduce LDL cholesterol levels and subsequently the risk of developing CHD. However, not all the aggressive statin therapy could decrease the risk of developing CHD. Many clinical and epidemiological studies have clearly demonstrated that the HDL cholesterol is inversely associated with risk of CHD and is a critical and independent component of predicting its risk. Elucidations of HDL metabolism give rise to therapeutic targets with potential to raising plasma HDL cholesterol levels, thereby reducing the risk of developing CHD. The concept of reverse cholesterol transport is based on the hypothesis that HDL displays an cardioprotective function, which is a process involved in the removal of excess cholesterol that is accumulated in the peripheral tissues (e.g., macrophages in the aortae) by HDL, transporting it to the liver for excretion into the feces via the bile. In this review, we summarize the latest advances in the role of the lymphatic route in reverse cholesterol transport, as well as the biliary and the non-biliary pathways for removal of cholesterol from the body. These studies will greatly increase the likelihood of discovering new lipid-lowering drugs, which are more effective in the prevention and therapeutic intervention of CHD that is the major cause of human death and disability worldwide.

Psoriasis-associated vascular disease: the role of HDL

Psoriasis is a chronic inflammatory systemic disease with a prevalence of 2-3%. Overwhelming evidence show an epidemiological association between psoriasis, cardiovascular disease and atherosclerosis. Cardiovascular disease is the most frequent cause of death in patients with severe psoriasis. Several cardiovascular disease classical risk factors are also increased in psoriasis but the psoriasis-associated risk persists after adjusting for other risk factors.Investigation has focused on finding explanations for these epidemiological data. Several studies have demonstrated significant lipid metabolism and HDL composition and function alterations in psoriatic patients. Altered HDL function is clearly one of the mechanisms involved, as these particles are of the utmost importance in atherosclerosis defense. Recent data indicate that biologic therapy can reverse both structural and functional HDL alterations in psoriasis, reinforcing their therapeutic potential.