Differential proteomic distribution of TTR (pre-albumin) forms in serum and HDL of patients with high cardiovascular risk

The Search for Associations of Serum Proteins with the Presence of Unstable Atherosclerotic Plaque in Coronary Atherosclerosis

To study the associations of blood proteins with the presence of unstable atherosclerotic plaques in the arteries of patients with coronary atherosclerosis using quantitative proteomics. The studies involved two groups of men with coronary atherosclerosis (group 1 (St) had only stable atherosclerotic plaques; group 2 (Ns) had only unstable atherosclerotic plaques, according to histological analysis of tissue samples); the average age of patients was 57.95 ± 7.22. Protein concentrations in serum samples were determined using the PeptiQuant Plus Proteomics Kit. The identification of protein fractions was carried out by monitoring multiple reactions on a Q-TRAP 6500 mass spectrometer combined with a liquid chromatograph. Mass spectrometric identification revealed in serum samples from patients with unstable atherosclerotic plaques a reduced concentration of proteins in the blood: α-1-acid glycoprotein, α-1-antichymotrypsin, α-1-antitrypsin, ceruloplasmin, hemopexin, haptoglobin, apolipoprotein B-100, apolipoprotein L1, afamin and complement component (C3, C7, C9). Moreover, at the same time a high concentration complements factor H and attractin. The differences were considered significant at p < 0.05. It was found that the instability of atherosclerotic plaques is associated with the concentration of proteins: afamin, attractin, components of the complement system, hemopexin and haptoglobin. The data of our study showed the association of some blood proteins with the instability of atherosclerotic plaques in coronary atherosclerosis. Their potential role in the development of this disease and the possibility of using the studied proteins as biomarkers requires further research.

Urinary Proteomic Signature in Acute Decompensated Heart Failure: Advances into Molecular Pathophysiology

Acute decompensated heart failure (ADHF) is a life-threatening clinical syndrome involving multi-organ function deterioration. ADHF results from multifaceted, dysregulated pathways that remain poorly understood. Better characterization of proteins associated with heart failure decompensation is needed to gain understanding of the disease pathophysiology and support a more accurate disease phenotyping. In this study, we used an untargeted mass spectrometry (MS) proteomic approach to identify the differential urine protein signature in ADHF patients and examine its pathophysiological link to disease evolution. Urine samples were collected at hospital admission and compared with a group of healthy subjects by two-dimensional electrophoresis coupled to MALDI-TOF/TOF mass spectrometry. A differential pattern of 26 proteins (>1.5-fold change, p < 0.005), mostly of hepatic origin, was identified. The top four biological pathways (p < 0.0001; in silico analysis) were associated to the differential ADHF proteome including retinol metabolism and transport, immune response/inflammation, extracellular matrix organization, and platelet degranulation. Transthyretin (TTR) was the protein most widely represented among them. Quantitative analysis by ELISA of TTR and its binding protein, retinol-binding protein 4 (RBP4), validated the proteomic results. ROC analysis evidenced that combining RBP4 and TTR urine levels highly discriminated ADHF patients with renal dysfunction (AUC: 0.826, p < 0.001) and significantly predicted poor disease evolution over 18-month follow-up. In conclusion, the MS proteomic approach enabled identification of a specific urine protein signature in ADHF at hospitalization, highlighting changes in hepatic proteins such as TTR and RBP4.

Application of blood pre-albumin and NT-pro BNP levels in evaluating prognosis of elderly chronic heart failure patients

Levels of blood pre-albumin (PA) and N-terminal pro-B-type natriuretic peptide (NT-pro BNP) in elderly patients with chronic heart failure (CHF) and their clinical value in prognosis evaluation were explored. A total of 410 elderly patients aged ≥65 years hospitalized for CHF were enrolled. The concentrations of blood PA and NT-pro BNP, routine blood test and biochemistry indicators were determined and color Doppler echocardiography was performed. Additionally, the patients were followed up after discharge, and based on the occurrence of major adverse cardiac events (MACE), they were divided into MACE group and non-MACE group. MACE group had an older age and a higher level of plasma NT-pro BNP than non-MACE group (77.82±6.57) years vs. (76.39±6.18) years, and (8,864.52±9,718.36) pg/ml vs. (4,165.62+6,437.28) pg/ml (P<0.05), and the left ventricular ejection fraction and serum PA level in MACE group were lower than those in non-MACE group (P<0.05). According to the results of multivariate regression analysis, serum PA [odds ratio (OR)=0.242, 95% confidence interval (CI)=0.137-0.406, P<0.001] and plasma NT-pro BNP (OR=1.847, 95% CI=1.024-3.158, P=0.036) were independent risk factors for the occurrence of cardiac events during follow-up. Decline in PA level and elevation in NT-pro BNP level have a strong correlation with poor prognosis of elderly CHF patients, and they can be used for clinically evaluating disease conditions, guiding treatment and improving prognosis.

Changes in the proteomic profile of blood serum in coronary atherosclerosis

Background

Our aim was to study changes in the serum proteomic profile in coronary atherosclerosis.

Methods

The study involved two groups of patients: 1) men with coronary heart disease and coronary atherosclerosis (n = 15); 2) control (n = 15): men without coronary heart disease. The object of this study was blood serum. Separation of proteins for the investigation of differences in serum protein components was performed by two-dimensional electrophoresis. Identification of protein fractions was carried out using peptide mass maps by the matrix-assisted laser desorption ionization method.

Results

In blood serum samples from patients with coronary atherosclerosis, protein separation in two-dimensional gels with mass-spectrometric identification revealed an increase of some proteins: hemopexin, transthyretin (monomeric form), retinol-binding protein 4, and components of the complement system: C3 (chain B) and C9. There was a decrease of some proteins: kininogen, zinc finger protein 133, and B-cell CLL/lymphoma 6 member B protein. Comparisons between the experimental and control group were carried out in protein fractions where the protein amount differed more than 1.5-fold (p < 0.05).

Conclusions

Proteome profiling of serum revealed a change in the content of kininogen, hemopexin, transthyretin, retinol-binding protein, and proteins of the complement system (C9, and C3) in coronary atherosclerosis. The contribution to the differential expression of a protein was often made by isoforms of the protein, particularly transthyretin. The change in the concentrations of functionally interacting proteins, such as transthyretin and retinol-binding protein, were noted.

High sensitivity C-reactive protein to prealbumin ratio measurement as a marker of the prognosis in acute coronary syndrome

The study aimed to determine whether high sensitivity C-reactive protein to prealbumin (hs-CRP/PAB) ratio could be used to predict in-hospital major adverse cardiac events (MACE) in patients with acute coronary syndrome (ACS). A total of 659 patients with ACS were included in the study. Patients were divided into two groups: high hs-CRP/PAB ratio group (hs-CRP/PAB ≥0.010) and low hs-CRP/PAB ratio group (hs-CRP/PAB <0.010). MACE was defined as death, cardiogenic shock, re-infarction and acute heart failure. Logistic regression was performed and the receiver operating characteristic curve (ROC) was generated to evaluate the correlation of hs-CRP/PAB ratio and MACE in patients with ACS. The occurrence rate of MACE was significantly higher in high hs-CRP/PAB ratio group when compared with that in low hs-CRP/PAB ratio group (P < 0.001). Multivariable analysis determined that hs-CRP/PAB ratio was an independent predictor of MACE (adjusted odds ratio: 1.276, 95% confidence interval: 1.106–1.471, P = 0.001). Moreover, the area under the curve value of hs-CRP/PAB ratio for predicting MACE was higher than hs-CRP and equal to PAB. High hs-CRP/PAB ratio was considered as a prognostic parameter of MACE in ACS patients, with the predictive power equal to PAB but greater than hs-CRP.

The role of retinol-binding protein 4 and its relationship with sex hormones in coronary artery disease

The role of retinol-binding protein 4 (RBP4) in patients with coronary artery disease (CAD) with different sexes has not been clearly established. Sex hormones, especially testosterone (T) and estradiol (E2), have been considered to play an important role in CAD. This study aimed to investigate the role of RBP4 and the possible association between RBP4 and T and E2 in CAD. The study included 658 individuals who underwent coronary angiography (CAG); they were assigned to CAD group (n = 440) and controls (n = 218). CAD group was subdivided into three subgroups. Serum RBP4 and T were assayed by enzyme-linked immunosorbent assay. Serum E2 was measured using electrochemiluminescence immunoassay. For men, RBP4 levels were lower in CAD group, especially those with acute myocardial infarction, than in controls (P < 0.05, P < 0.01, respectively). For women, no significant difference was found in RBP4 levels between both groups. RBP4 was positively correlated with T in male patients with CAD (r = 0.124, P < 0.05). Logistic regression analysis showed that RBP4 was a protective factor for CAD (odds ratio 0.975, 95% confidence interval 0.958-0.993; P = 0.007). In conclusion, RBP4 levels were significantly decreased and positively related with T in men with CAD. Higher RBP4 levels were associated with lower risk of CAD. RBP4 may play a potential protective role for CAD among men.

Low serum prealbumin levels on admission can independently predict in-hospital adverse cardiac events in patients with acute coronary syndrome

The aim of this study is to evaluate if low prealbumin levels on admission predict subsequent adverse cardiac events in patients hospitalized with acute coronary syndrome (ACS).We designed a cohort study and enrolled 610 consecutive patients with ACS from whom venous blood for serum prealbumin measurement was drawn immediately upon hospital admission. Patients were classified in two groups according to prealbumin level: "normal" prealbumin levels (≥17 mg/dL, n=413) and "low" prealbumin (<17 mg/dL, n = 197). In-hospital adverse cardiac events were death, acute heart failure, reinfarction, and cardiogenic shock. Univariate and multivariable analyses were applied to evaluate the prediction value of low prealbumin.The incidence of in hospital adverse cardiac events is 10.8%. The proportion of adverse cardiac events was significantly higher in low prealbumin group as compared with normal prealbumin group (20.8% versus 6.1%, P < .001). Univariate analysis indicates that low prealbumin levels can predict in hospital adverse cardiac events (odds ratio [OR]: 0.834, 95% confidence interval [CI]: 0.785-0.886, P < .001). Multivariable analysis shows that low prealbumin level was an independent predictor for in hospital adverse cardiac events (adjusted OR: 0.918, 95% CI: 0.848-0.993, P = .033). Other independent predictors were lower in average hemoglobin level and Killip class II-IV on admission.Therefore, lower serum prealbumin levels on admission can independently predicts subsequent in hospital major adverse cardiac events in patients with ACS.

Pediatric endocrine and metabolic diseases and proteomics

The principles of Predictive, Preventive and Personalized Medicine (PPPM) dictate the need to recognize individual susceptibility to disease in a timely fashion and to offer targeted preventive interventions and treatments. Proteomics is a state-of-the art technology- driven science aiming at expanding our understanding of the pathophysiologic mechanisms that underlie disease, but also at identifying accurate predictive, diagnostic and therapeutic biomarkers, that will eventually promote the implementation of PPPM. In this review, we summarize the wide spectrum of the applications of Mass Spectrometry-based proteomics in the various fields of Pediatric Endocrinology, including Inborn Errors of Metabolism, type 1 diabetes, Adrenal Disease, Metabolic Syndrome and Thyroid disease, ranging from neonatal screening to early recognition of specific at-risk populations for disease manifestations or complications in adult life and to monitoring of disease progression and response to treatment.

SIGNIFICANCE

Proteomics is a state-of-the art technology- driven science aiming at expanding our understanding of the pathophysiologic mechanisms that underlie disease, but also at identifying accurate predictive, diagnostic and therapeutic biomarkers that will eventually lead to successful, targeted, patient-centric, individualized approach of each patient, as dictated by the principles of Predictive, Preventive and Personalized Medicine. In this review, we summarize the wide spectrum of the applications of Mass Spectrometry-based proteomics in the various fields of Pediatric Endocrinology, including Inborn Errors of Metabolism, type 1 diabetes, Adrenal Disease, Metabolic Syndrome and Thyroid disease, ranging from neonatal screening, accurate diagnosis, early recognition of specific at-risk populations for the prevention of disease manifestation or future complications.

Q-Rich Yeast Prion [PSI+] Accelerates Aggregation of Transthyretin, a Non-Q-Rich Human Protein

Interactions amongst different amyloid proteins have been proposed as a probable mechanism of aggregation and thus an important risk factor for the onset as well as progression of various neurodegenerative disorders including Alzheimer's, Parkinson's, Huntington's, and Amyotrophic Lateral Sclerosis. Evidences suggest that transthyretin (TTR), a plasma protein associated with transthyretin amyloidosis or familial polyneuropathy (FAP) interacts with heterologous amyloid proteins including amyloid beta and islet amyloid polypeptide. In addition, recent clinical studies have revealed the presence of systemic polyneuropathy associated with FAP mutations in patients with spinocerebral ataxia, amyotrophic lateral sclerosis, and new familial systematic prion disease. Hence, it is important to investigate the interactions amongst different amyloid proteins to gain better insight into the pathology of amyloid disorders. Yeast has been an excellent model system to study interaction/ cross-seeding between heterologous amyloid proteins, more because of presence of endogenous yeast prions. Here, we examined interactions of non-glutamine (non-Q)-rich transthyretin, with glutamine (Q)-rich yeast prion protein Sup35. We established aggregation of an engineered double (F87M/L110M) mutant M-TTR-GFP in yeast. This mutant is monomeric and readily formed aggregates compared to WT-TTR-GFP in yeast at acidic pH. Interestingly, aggregation of M-TTR-GFP was significantly enhanced in presence of [PSI⁺], an endogenous prion form of Sup35. Different variants of [PSI⁺] seeded M-TTR-GFP with different efficiencies and curing of [PSI⁺] (losing the prion form) in these strains reduced aggregation. Moreover, overexpression of prion domain of Sup35 fused to RFP (NM-RFP) also increased M-TTR-GFP aggregation. M-TTR-GFP and NM-RFP aggregates co-localized in perivacuolar and juxtranuclear region. Sup35 protein was even immunocaptured in M-TTR-GFP aggregates. However, M-TTR-GFP overexpression did not induce Sup35 aggregation. Thus, it appears to be a unidirectional interaction between these two amyloid proteins. However, no affect on M-TTR-GFP aggregation was observed due to another yeast prion, [PIN⁺]. Our findings thus show the molecular interaction of transthyretin with yeast prion and support that sequence similarity is not the prime requirement for heterologous amyloid interactions.

Pharmacological Intervention to Modulate HDL: What Do We Target?

The cholesterol concentrations of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) have traditionally served as risk factors for cardiovascular disease. As such, novel therapeutic interventions aiming to raise HDL cholesterol have been tested in the clinical setting. However, most trials led to a significant increase in HDL cholesterol with no improvement in cardiovascular events. The complexity of the HDL particle, which exerts multiple physiological functions and is comprised of a number of subclasses, has raised the question as to whether there should be more focus on HDL subclass and function rather than cholesterol quantity. We review current data regarding HDL subclasses and subclass-specific functionality and highlight how current lipid modifying drugs such as statins, cholesteryl ester transfer protein inhibitors, fibrates and niacin often increase cholesterol concentrations of specific HDL subclasses. In addition this review sets out arguments suggesting that the HDL3 subclass may provide better protective effects than HDL2.

High-molecular-weight kininogen and the intrinsic coagulation pathway in patients with de novo acute myocardial infarction

After an acute ischaemic event serum proteins may change reflecting the ischaemic damage. Proteomic studies could provide new insights into potential biomarkers in the evolution of ischaemic syndromes. In this study we have investigated the coordinated changes in coagulation-related proteins in the evolution after an acute myocardial infarction (AMI). Serum proteome (2D-electrophoresis and MALDI-TOF/ TOF) of AMI-patients within the first 6 hours after event onset (admission-time) and 3 days after were compared to controls. Systems biology and bioinformatic analysis were performed to identify the differentially expressed canonical pathways. In silico analysis of differential proteins revealed changes in the intrinsic coagulation pathway in the early phase post-AMI. The two identified high-molecular weight kininogen (HMWK) clusters were inversely correlated in AMI patients at admission, being the intensity of the low-molecular-weight form inversely related to myocardial necrosis (p<0.05). Factor XI (FXI) levels were decreased in AMI patients at admission and normalised 3 days after (p<0.05). There was an early increase in fibrinogen gamma and D-dimer at admission, followed by a decrease in fibrinogen turnover 3 days after (p<0.05). The influence of elapsed time of ischaemia on fibrinogen distribution changes was validated in coronary thrombi retrieved by thromboaspiration. In conclusion, our results demonstrate an active exchange between HMWK forms and a decrease in FXI indicative of intrinsic pathway activation, together with an increase in fibrinogen gamma turnover and D-dimer formation in the early phase post-AMI. Moreover, coronary thrombi showed a dynamic evolution in fibrinogen composition depending on the duration of ischaemia influencing serum fibrinogen-related products content.

Protein changes in non-LDL-lipoproteins in familial hypercholesterolemia: implications in cardiovascular disease manifestation and outcome

PURPOSE OF REVIEW

Familial hypercholesterolemia, represents one of the most extreme clinical entities associated with premature coronary artery disease (CAD). However, clinical manifestation of CAD varies across cohorts and individual patients suggesting the existence of additional non-LDL factors potentially contributing to their cardiovascular burden.

RECENT FINDINGS

Changes in HDL-associated proteins appear as one of the potential additional factors contributing to the cardiovascular risk in familial hypercholesterolemia. Specifically, the content of Apo M-SP1 in HDL3 has been directly associated with cholesterol efflux capacity. In addition, a coordinated decrease in the content of Apo L1 and LCAT in HDL3 has been related to the presence of corneal arcus and to bad prognosis in familial hypercholesterolemia patients after an acute ischemic event. In fact, HDL3 particles of familial hypercholesterolemia patients have diminished antioxidant and anti-inflammatory function.

SUMMARY

The identification of the specific changes in HDL-associated proteins that contribute to the increased cardiovascular risk of familial hypercholesterolemia patients could be useful for the development of novel therapeutic targets. These novel strategies, in combination with current lipid-lowering therapies, may help to reduce the residual risk found in these patients.

Detrimental Effect of Hypercholesterolemia on High-Density Lipoprotein Particle Remodeling in Pigs

BACKGROUND

Beneficial effects of high-density lipoproteins (HDL) seem altered in patients with symptomatic cardiovascular disease. We recently demonstrated in a swine model of ischemia-reperfusion (IR) that hypercholesterolemia abolishes HDL-related cardioprotection.

OBJECTIVES

This study sought to investigate, using the same animal model, whether the reported impairment of HDL cardioprotective function was associated with alterations in HDL remodeling and functionality.

METHODS

Pigs were fed a normocholesterolemic (NC) or hypercholesterolemic (HL) diet for 10 days, reaching non-HDL cholesterol concentrations of 38.2 ± 3.5 mg/dl and 218.6 ± 27.6 mg/dl, respectively (p < 0.0001). HDLs were isolated, and lipidomics and differential proteomics tests were performed to determine HDL molecular changes. HDL functionality and particle size were determined.

RESULTS

Using principal component analysis, we identified 255 molecular lipid species differentially clustered in NC-HDL and HL-HDL. Ninety lipid metabolites were differentially expressed, and 50 showed at least 1.5-fold variation (false discovery rate adjustment q value <0.05). HL-HDLs presented a core enriched in cholesteryl esters and a surface depleted of phosphatidylcholine species containing polyunsaturated and long-chain fatty acids, indicating the presence of mature HDL particles with low surface fluidity. Hypercholesterolemia induced an important change in HDL-transported proteins (576 spots in HL-HDL vs. 621 spots in NC-HDL). HL-HDLs showed a reduced content of lipocalin retinol binding protein 4 and apolipoprotein M and in the retinoic acid-transporter cellular retinoic acid binding protein 1 (p < 0.05 vs. NC-HDL). No changes were observed in apolipoprotein A-I content and profile. Functionally, HL-HDL showed lower antioxidant activity (-35%) and a reduced capacity to efflux cholesterol (-60%) compared to NC-HDL (p < 0.05). Hypercholesterolemia induced larger HDL particles.

CONCLUSIONS

We demonstrate that hypercholesterolemia induces HDL lipidomic changes, losing phosphatidylcholine-lipid species and gaining cholesteryl esters, and proteomic changes, with losses in cardioprotective proteins. These remodeling changes shifted HDL particles toward a dysfunctional state.

Proteomic analysis allows for identifying targets of Yinchenwuling Powder in hyperlipidemic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Yinchenwuling Powder (YCL) is a traditional Chinese medicine formula originated from Synopsis of Golden Chamber, which is effective in positively modulating lipid levels in clinics. In this study, we utilized proteomic technology to identify the therapeutic targets of YCL on hyperlipidemic rats.

METHODS

We established hyperlipidemic model rats and administrated them with different doses of YCL extracts (0.35g/ml, 0.75g/ml and 1.5g/ml). Serum lipid levels were quantified and proteomic analysis was performed on plasma samples at the end of the study. Total plasma proteins were separated by two-dimensional electrophoresis (2-DE), and protein spots with 1.5-fold difference were excised and then analyzed by MALDI-TOF MS. Proteomic results were verified by Western blotting.

RESULTS

The results showed that the serum levels of TC, TG, and LDL-C were significantly decreased, while the HDL-C levels were significantly increased in different doses of YCL treatment groups. After being analyzed by 2-DE and MALDI-TOF MS, 12 proteins were identified. Eight proteins (T-kininogen, C3, C4, C4BPA, Igλ-2 chain C, Mbl2, Hpx and FGL1) were up-regulated in hyperlipidemic model rats, while four proteins (ApoE, ALB, TTR and VDBP) were up-regulated in the control and the YCL-treated rats. Two plasma proteins, ApoE and FGL1, involved in lipid metabolism, were confirmed by western blotting, and the results were consistent with the data from the proteomics results.

CONCLUSIONS

In this experiment, we identified 12 differentially-expressed plasma proteins associated with therapeutic effects of YCL. The functions of those proteins are related with lipid metabolism, blood coagulation, anti-inflammation and substance transport. This study provided a clue for the mechanism that underlies the therapeutic effect of YCL on lipid metabolism.

ApoL1 levels in high density lipoprotein and cardiovascular event presentation in patients with familial hypercholesterolemia

HDL composition rather than HDL-cholesterol (HDL-C) levels seems to be a key determinant of HDL-induced atheroprotection. Heterozygous familial hypercholesterolemia (FH) patients, with lifelong exposure to high LDL levels, show a high prevalence of premature coronary artery disease. We hypothesized that HDL of FH patients might have a modified protein composition and investigated the proteomic signature of HDL obtained from FH patients and their unaffected relatives. HDLs were characterized by 2D electrophoresis/MS in 10 families from the SAFEHEART cohort (3 individuals/family: 2 with genetic FH diagnosis and 1 non-FH relative) clinically characterized and treated as per guidelines. FH patients had lower apoA-I levels and a differential HDL distribution profile of apoL1 and apoA-IV. ELISA validation revealed decreased apoL1 serum levels in FH patients. ApoL1 levels were able to predict presentation of an ischemic cardiac event, and apoL1/HDL-C ratio was associated with the survival rate after the event. FH patients who died because of a fatal cardiac event had lower apoL1 and LCAT content in HDL3 an average of 3.5 years before the event than those who survived. Changes in HDL protein composition could affect patients' prognosis. The proteomic profile of apoL1 is modified in HDLs of high cardiovascular risk patients, and apoL1 plasma levels are significantly lower in serum and in HDL3 of patients that will suffer an adverse cardiac event within 3 years.

Prevalence, Treatment, and Control of Hypercholesterolemia in High Cardiovascular Risk Patients: Evidences from a Systematic Literature Review in Spain

Introduction

Cardiovascular diseases (CVDs) represent a major Public Health burden. High serum cholesterol levels have been linked to major CV risk. The objectives of this study were to review the epidemiology of hypercholesterolemia in high risk CV patients from Spain, by assessing its prevalence, the proportion of diagnosed patients undergoing pharmacological treatment and the degree of attained lipid control.

Methods

A systematic literature review was carried out using Medline and two Spanish databases. Manuscripts containing information on hypercholesterolemia in several high CV risk groups [diabetes mellitus (DM), Systematic COronary Risk Evaluation (SCORE) risk >5, or documented CVD], published between January 2010 and October 2014, were included.

Results

Of the 1947 published references initially retrieved, a full-text review was done on 264 manuscripts and 120 were finally included. Prevalence of hypercholesterolemia ranged from 50 to 84% in diabetics, 30–60% in patients with DM or elevated SCORE risk, 64–74% with coronary heart disease, 40–70% in stroke patients, and 60–80% in those with peripheral artery disease. Despite the finding that most of them were on pharmacological treatment, acceptable control of serum lipids was very variable, ranging from 15% to 65%. Among those with heterozygous familial hypercholesterolemia, 95–100% received treatment but less than 50% achieved their therapeutic goals.

Conclusions

An elevated prevalence of hypercholesterolemia can be found in targeted groups at high CV risk. Although most patients are receiving pharmacological treatment, rates of lipid control continue to be low, both in primary and secondary prevention.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-015-0252-y) contains supplementary material, which is available to authorized users.

Mass Spectrometry-Based Proteomic Study Makes High-Density Lipoprotein a Biomarker for Atherosclerotic Vascular Disease

High-density lipoprotein (HDL) is a lipid and protein complex that consists of apolipoproteins and lower level HDL-associated enzymes. HDL dysfunction is a factor in atherosclerosis and decreases patient survival. Mass spectrometry- (MS-) based proteomics provides a high throughput approach for analyzing the composition and modifications of complex HDL proteins in diseases. HDL can be separated according to size, surface charge, electronegativity, or apoprotein composition. MS-based proteomics on subfractionated HDL then allows investigation of lipoprotein roles in diseases. Herein, we review recent developments in MS-based quantitative proteomic techniques, HDL proteomics and lipoprotein modifications in diseases, and HDL subfractionation studies. We also discuss future directions and perspectives in MS-based proteomics on HDL.

The serum protein fetuin-B is involved in the development of acute myocardial infarction

Fetuin-B was one of highly expressed serum proteins in AMI compared with stable angina. This protein affected vascular plaque-stabilizing components in monocytes, macrophages and vascular smooth muscle cells. Fetuin-B may be a possible contributor to AMI.

Retinol-binding protein 4 and its potential roles in hypercholesterolemia revealed by proteomics

Effects of hypercholesterolemia on alterations of serum proteins have not been fully elucidated. Herein, using two-dimensional gel electrophoresis (2-DE) in conjunction with LC-MS searching has successfully been carried out to investigate the change of protein expression profiles as consequences of raised blood cholesterol at different levels (normal group: total cholesterol 200 mg/dL; borderline high group: total cholesterol 200-239 mg/dL; and high group: total cholesterol ≥ 240 mg/dL) (n = 45). Results revealed that down-regulation of retinol-binding protein 4 (RBP4) (-2.26 fold), transthyretin (-1.25 fold) and gelsolin (-1.47 fold) was observed in the high group. Meanwhile, the other proteins such as haptoglobin, complement factor B and CD5 antigen-like protein were up-regulated upto +3.24, +1.96 and +2.04 fold, respectively. Confirmation by Western blotting revealed a significant reduction of RBP4 (approximately 50 %) in individual samples derived from the high group. Presumptive conclusion can be drawn that down-regulation of RBP4 might be attributable to the inflammation of adipocytes caused by the release of proinflammatory cytokines (e.g. tumor necrosis factor α and interleukin-1β) from adipose tissues. Moreover, the decrease of transthyretin might also be taken into accounts since it is known that the transthyretin usually forms complex with RBP4 to prevent glomerular filtration and excretion through the kidney. The suppressing effect on RBP4 should be potentiated by the increase of complement factor B and CD5 antigen-like protein, which rendered the adipose tissues to overwhelm the liberation of RBP4 to blood circulation by metabolic and inflammatory processes. Such inflammation could further modulate the induction of cytokine release (e.g. IL-6 and IL-1β), resulting in the synthesis of acute phase protein, in particular, haptoglobin and C-reactive proteins from hepatocytes. However, the mechanism of gelsolin reduction remains unclear. Among these differentially expressed proteins, the RBP4 has been proposed as a major linkage between hypercholesterolemia, adipose tissues, liver and kidney, which is believed to be a potential biomarker for metabolic and cardiovascular disorders associated with dyslipidemia in the future.

Glycoproteome of human apolipoprotein A-I: N- and O-glycosylated forms are increased in patients with acute myocardial infarction

High-density lipoprotein (HDL) functionality, which is closely associated with its composition and transport capabilities, determines its role in atheroprotection. During acute phase processes, HDL seems to lose its anti-inflammatory and cytoprotective properties. In this study, we hypothesized that after an acute myocardial infarction apolipoprotein (Apo) A-I, the main protein component of HDL, might undergo changes in its molecular processing. Therefore, we have characterized the Apo A-I proteome during the evolution of new-onset acute myocardial infarction (AMI). To this end, serum Apo A-I was characterized by 2-dimensional electrophoresis/mass-spectrometry in controls and AMI patients at admission (within the first 6 hours after pain onset) and 8 hours, 16 hours, 24 hours, and 3 days afterward. The Apo A-I glycoproteome was analyzed by lectin-based glycoprotein isolation methods and deglycosylation assays, and Apo A-I serum levels were evaluated by enzyme-linked immunosorbent assay (ELISA). The Apo A-I proteomic signature (5 spots: 28 kDa/pI:5-5.75) was significantly altered in AMI patients 3 days after the event with respect to controls. Increased levels of N- and O-glycosylated Apo A-I forms were found post-AMI. Apo A-I serum levels measured by ELISA were significantly changed and related to left ventricular ejection fraction, troponin-T, and C-reactive protein. The Apo A-I molecule measured by ELISA corresponded to the main glycosylated spots and was specifically O-GlcNAcylated in AMI patients. Therefore, our results demonstrate that Apo A-I is both N- and O-glycosylated and that there is an increase in Apo A-I glycosylation after AMI. Furthermore, the specific increase in the O-GlcNAcylated forms could have a relevant prognostic value and a protective role in the evolution of AMI.

Modifications in rat plasma proteome after remote ischemic preconditioning (RIPC) stimulus: identification by a SELDI-TOF-MS approach

Remote ischemic preconditioning’s (RIPC) ability to render the myocardium resistant to subsequent prolonged ischemia is now clearly established in different species, including humans. Strong evidence suggests that circulating humoral mediators play a key role in signal transduction, but their identities still need to be established. Our study sought to identify potential circulating RIPC mediators using a proteomic approach. Rats were exposed to 10-min limb ischemia followed by 5- (RIPC 5′) or 10-min (RIPC 10′) reperfusion prior to blood sampling. The control group only underwent blood sampling. Plasma samples were isolated for proteomic analysis using surface-enhanced laser desorption and ionization - time of flight - mass spectrometry (SELDI-TOF-MS). A total of seven proteins, including haptoglobin and transthyretin, were detected as up- or down-regulated in response to RIPC. These proteins had previously been identified as associated with organ protection, anti-inflammation, and various cellular and molecular responses to ischemia. In conclusion, this study indicates that RIPC results in significant modulations of plasma proteome.

Retinol-binding protein 4 levels and susceptibility to ischaemic events in men

BACKGROUND

Many efforts in cardiovascular medicine have been focused in the identification of patients at risk of developing an acute ischaemic event. Biomarker discovery studies have become an essential research area, being proteomic technologies an excellent tool for biomarker identification. By applying proteomic approaches, we have detected changes in retinol-binding protein 4 (RBP4) in acute new-onset myocardial infarction patients (AMI) and in high-risk patients with heterozygous familial hypercholesterolaemia (FH).

MATERIALS AND METHODS

Differential serum proteome was analysed by two-dimensional electrophoresis and MALDI-TOF/TOF. Validation studies were performed by ELISA, and functional effects of RBP4 were tested in cell culture experiments.

RESULTS

Retinol-binding protein 4 proteomic characterization depicted two spots (pI = 5·4;Mw = 23·01/22·78 kDa) with decreased intensity in AMI patients. Total serum RBP4 levels were decreased in AMI patients (N = 68) compared with controls (N = 132; P < 0·0001). RBP4 was also decreased in FH patients who had an ischaemic event 2 years (±0·3) after their inclusion compared with FH patients without any cardiovascular episode at follow-up (P < 0·001; N = 187). In both cases, changes were limited to men. RBP4 induced a significant increase in eNOS expression in human endothelial vascular cells and in prostaglandin I2 release in coronary vascular smooth muscle cells.

CONCLUSIONS

We show decreased serum RBP4 levels in men in the acute phase of AMI, being this decrease already detected in men with FH previous to the presentation of an ischaemic event. The decrease in RBP4 levels could confer an increased susceptibility to the precipitation of an ischaemic event that could be mediated by the decrease in its vasculoprotective properties through NO and PGI2 .

Proteomic analysis of plasma-purified VLDL, LDL, and HDL fractions from atherosclerotic patients undergoing carotid endarterectomy: identification of serum amyloid A as a potential marker

Apolipoproteins are very heterogeneous protein family, implicated in plasma lipoprotein structural stabilization, lipid metabolism, inflammation, or immunity. Obtaining detailed information on apolipoprotein composition and structure may contribute to elucidating lipoprotein roles in atherogenesis and to developing new therapeutic strategies for the treatment of lipoprotein-associated disorders. This study aimed at developing a comprehensive method for characterizing the apolipoprotein component of plasma VLDL, LDL, and HDL fractions from patients undergoing carotid endarterectomy, by means of two-dimensional electrophoresis (2-DE) coupled with Mass Spectrometry analysis, useful for identifying potential markers of plaque presence and vulnerability. The adopted method allowed obtaining reproducible 2-DE maps of exchangeable apolipoproteins from VLDL, LDL, and HDL. Twenty-three protein isoforms were identified by peptide mass fingerprinting analysis. Differential proteomic analysis allowed for identifying increased levels of acute-phase serum amyloid A protein (AP SAA) in all lipoprotein fractions, especially in LDL from atherosclerotic patients. Results have been confirmed by western blotting analysis on each lipoprotein fraction using apo AI levels for data normalization. The higher levels of AP SAA found in patients suggest a role of LDL as AP SAA carrier into the subendothelial space of artery wall, where AP SAA accumulates and may exert noxious effects.

Effects of cholesteryl ester transfer protein inhibitors on human lipoprotein metabolism: why have they failed in lowering coronary heart disease risk?

PURPOSE OF REVIEW

To examine the recent advances in our knowledge of cholesteryl ester transfer protein (CETP) inhibitors, heart disease risk reduction, and human lipoprotein metabolism.

RECENT FINDINGS

CETP inhibitors block the transfer of cholesteryl ester from HDLs to triglyceride-rich lipoproteins (TRLs), thereby raising HDL cholesterol and lowering TRL cholesterol, and in some cases LDL cholesterol. Two CETP inhibitors, dalcetrapib and torcetrapib, have been tested in large clinical trials in statin-treated coronary heart disease patients and have shown no clinical benefit compared to placebo. Anacetrapib and evacetrapib, two potent CETP inhibitors, are now being tested in large clinical trials. Torcetrapib has been shown to decrease the fractional catabolic rate (FCR) of HDL apolipoproteins (apo) A-I and A-II, enhance the FCR of TRL apoB-100 and apoE, and decrease TRL apoB-48 production, but has no significant effects on fecal cholesterol excretion in humans. Anacetrapib also delays the FCR of HDL apoA-I.

SUMMARY

CETP inhibitors form a complex between themselves, CETP, and HDL particles, which may interfere with the many physiologic functions of HDL, including reverse cholesterol transport. Available data would suggest that CETP inhibitors will fail as lipid-altering medications to reduce coronary heart disease risk because of interference with normal human HDL metabolism.