Zebrafish ApoB-Containing Lipoprotein Metabolism: A Closer Look

Zebrafish have become a powerful model of mammalian lipoprotein metabolism and lipid cell biology. Most key proteins involved in lipid metabolism, including cholesteryl ester transfer protein, are conserved in zebrafish. Consequently, zebrafish exhibit a human-like lipoprotein profile. Zebrafish with mutations in genes linked to human metabolic diseases often mimic the human phenotype. Zebrafish larvae develop rapidly and externally around the maternally deposited yolk. Recent work revealed that any disturbance of lipoprotein formation leads to the accumulation of cytoplasmic lipid droplets and an opaque yolk, providing a visible phenotype to investigate disturbances of the lipoprotein pathway, already leading to discoveries in MTTP (microsomal triglyceride transfer protein) and ApoB (apolipoprotein B). By 5 days of development, the digestive system is functional, making it possible to study fluorescently labeled lipid uptake in the transparent larvae. These and other approaches enabled the first in vivo description of the STAB (stabilin) receptors, showing lipoprotein uptake in endothelial cells. Various zebrafish models have been developed to mimic human diseases by mutating genes known to influence lipoproteins (eg, ldlra, apoC2). This review aims to discuss the most recent research in the zebrafish ApoB-containing lipoprotein and lipid metabolism field. We also summarize new insights into lipid processing within the yolk cell and how changes in lipid flux alter yolk opacity. This curious new finding, coupled with the development of several techniques, can be deployed to identify new players in lipoprotein research directly relevant to human disease.

Depleting LCAT Aggravates Atherosclerosis in LDLR-deficient Hamster with Reduced LDL-Cholesterol Level

INTRODUCTION

Lecithin cholesterol acyltransferase (LCAT) plays a crucial role in acyl-esterifying cholesterol in plasma, which is essential for reverse cholesterol transport (RCT). Previous studies indicated that its activity on both α and β lipoproteins interpret its effects on lipoproteins for many controversial investigations of atherosclerosis.

OBJECTIVES

To better understand the relationship between LCAT, diet-induced dyslipidemia and atherosclerosis, we developed a double knockout (LCAT-/-&LDLR-/-, DKO) hamster model to evaluate the specific role of LCAT independent of LDL clearance effects.

METHODS

Plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), and free cholesterol (FC) levels were measured using biochemical reagent kits. FPLC was performed to analyze the components of lipoproteins. Apolipoprotein content was assessed using western blotting (WB). The hamsters were fed a high cholesterol/high fat diet (HCHFD) to induce atherosclerosis. Oil Red O staining was employed to detect plaque formation. Peritoneal macrophages were studied to investigate the effects of LCAT on cholesterol uptake and efflux.

RESULTS

On HCHFD, DKO hamsters exhibited significantly elevated levels of TG and FC, while HDL-C was nearly undetectable without affecting TC levels, as compared to low-density lipoprotein receptor (LDLR)-deficient (LDLR-/-, LKO) hamsters. Lipoprotein profiling revealed a marked increase in plasma chylomicron/very low-density lipoprotein (CM/VLDL) fractions, along with an unexpected reduction in LDL fraction in DKO hamsters. Furthermore, DKO hamsters displayed aggravated atherosclerotic lesions in the aorta, aortic root, and coronary artery relative to LKO hamsters, attributed to a pro-atherogenic lipoprotein profile and impaired cholesterol efflux in macrophages.

CONCLUSIONS

Our study demonstrates the beneficial role of LCAT in inhibiting atherosclerotic development and highlights the distinctive lipid metabolism characteristics in hamsters with familial hypercholesterolemia.

Role and therapeutic potential of gelsolin in atherosclerosis

Atherosclerosis is the major pathophysiological basis of a variety of cardiovascular diseases and has been recognized as a lipid-driven chronic inflammatory disease. Gelsolin (GSN) is a member of the GSN family. The main function of GSN is to cut and seal actin filaments to regulate the cytoskeleton and participate in a variety of biological functions, such as cell movement, morphological changes, metabolism, apoptosis and phagocytosis. Recently, more and more evidences have demonstrated that GSN is Closely related to atherosclerosis, involving lipid metabolism, inflammation, cell proliferation, migration and thrombosis. This article reviews the role of GSN in atherosclerosis from inflammation, apoptosis, angiogenesis and thrombosis.

Influence of lecithin cholesterol acyltransferase alteration during different pathophysiologic conditions: A 45 years bibliometrics analysis

Background: Lecithin cholesterol acyltransferase (LCAT) is an important enzyme responsible for free cholesterol (FC) esterification, which is critical for high density lipoprotein (HDL) maturation and the completion of the reverse cholesterol transport (RCT) process. Plasma LCAT activity and concentration showed various patterns under different physiological and pathological conditions. Research on LCAT has grown rapidly over the past 50 years, but there are no bibliometric studies summarizing this field as a whole. This study aimed to use the bibliometric analysis to demonstrate the trends in LCAT publications, thus offering a brief perspective with regard to future developments in this field. Methods: We used the Web of Science Core Collection to retrieve LCAT-related studies published from 1975 to 2020. The data were further analyzed in the number of studies, the journal which published the most LCAT-related studies, co-authorship network, co-country network, co-institute network, co-reference and the keywords burst by CiteSpace V 5.7. Results: 2584 publications contained 55,311 references were used to analyzed. The number of included articles fluctuated in each year. We found that Journal of lipid research published the most LCAT-related studies. Among all the authors who work on LCAT, they tend to collaborate with a relatively stable group of collaborators to generate several major authors clusters which Albers, J. published the most studies (n = 53). The United States of America contributed the greatest proportion (n = 1036) of LCAT-related studies. The LCAT-related studies have been focused on the vascular disease, lecithin-cholesterol acyltransferase reaction, phospholipid, cholesterol efflux, chronic kidney disease, milk fever, nephrotic syndrome, platelet-activating factor acetylhydrolase, reconstituted lpa-i, reverse cholesterol transport. Four main research frontiers in terms of burst strength for LCAT-related studies including "transgenic mice", "oxidative stress", "risk", and "cholesterol metabolism "need more attention. Conclusion: This is the first study that demonstrated the trends and future development in LCAT publications. Further studies should focus on the accurate metabolic process of LCAT dependent or independent of RCT using metabolic marker tracking techniques. It was also well worth to further studying the possibility that LCAT may qualify as a biomarker for risk prediction and clinical treatment.

CD5L-associated gene analyses highlight the dysregulations, prognostic effects, immune associations, and drug-sensitivity predicative potentials of LCAT and CDC20 in hepatocellular carcinoma

BACKGROUND

The dysregulation of CD5L has been reported in hepatocellular carcinoma (HCC). However, its functions in HCC were controversial. In this study, we aimed to identify CD5L-associated pathways and markers and explore their values in HCC diagnosis, prognosis and treatment.

METHODS

HCC datasets with gene expression profiles and clinical data in TCGA and ICGC were downloaded. The immune/stroma cell infiltrations were estimated with xCell. CD5L-associated pathways and CD5L-associated genes (CD5L-AGs) were identified with gene expression comparisons and gene set enrichment analysis (GSEA). Cox regression, Kaplan-Meier survival analysis, and least absolute shrinkage and selection operator (LASSO) regression analysis were performed. The correlations of the key genes with immune/stroma infiltrations, immunoregulators, and anti-cancer drug sensitivities in HCC were investigated. At protein level, the key genes dysregulations, their correlations and prognostic values were validated in clinical proteomic tumor analysis consortium (CPTAC) database. Serum CD5L and LCAT activity in 50 HCC and 30 normal samples were evaluated and compared. The correlations of serum LCAT activity with alpha-fetoprotein (AFP), albumin (ALB) and high-density lipoprotein (HDL) in HCC were also investigated.

RESULTS

Through systemic analyses, 14 CD5L-associated biological pathways, 256 CD5L-AGs and 28 CD5L-associated prognostic and diagnostic genes (CD5L-APDGs) were identified. A risk model consisting of LCAT and CDC20 was constructed for HCC overall survival (OS), which could discriminate HCC OS status effectively in both the training and the validation sets. CD5L, LCAT and CDC20 were shown to be significantly correlated with immune/stroma cell infiltrations, immunoregulators and 31 anti-cancer drug sensitivities in HCC. At protein level, the dysregulations of CD5L, LCAT and CDC20 were confirmed. LCAT and CDC20 were shown to be significantly correlated with proliferation marker MKI67. In serum, no significance of CD5L was shown. However, the lower activity of LCAT in HCC serum was obvious, as well as its significant positive correlations ALB and HDL concentrations.

CONCLUSIONS

CD5L, LCAT and CDC20 were dysregulated in HCC both at mRNA and protein levels. The LCAT-CDC20 signature might be new predicator for HCC OS. The associations of the three genes with HCC microenvironment and anti-cancer drug sensitivities would provide new clues for HCC immunotherapy and chemotherapy.

Kidney and lipids: novel potential therapeutic targets for dyslipidemia in kidney disease?

INTRODUCTION

Altered lipid distribution and metabolism may lead to the development and/or progression of chronic kidney disease (CKD). Dyslipidemia is a major risk factor for CKD and increases the risk of cardiovascular events and mortality. Therefore, lipid-lowering treatments may decrease cardiovascular risk and prevent death.

AREAS COVERED

Key players involved in regulating lipid accumulation in the kidney; contribution of lipids to CKD progression, lipotoxicity, and mitochondrial dysfunction in kidney disease; recent therapeutic approaches for dyslipidemia.

EXPERT OPINION

The precise mechanisms for regulating lipid metabolism, particularly in kidney disease, are poorly understood. Guidelines for lipid-lowering therapy for CKD are controversial. Several hypolipemic therapies are available, but compared to others, statin therapy is the most common. No clinical trial has evaluated the efficacy of proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) in preventing cardiovascular events or improving kidney function among patients with CKD or kidney transplant recipients. Attractive alternatives, such as PCSK9-small interfering RNA (siRNA) molecules or evinacumab are available. Additionally, several promising agents, such as cyclodextrins and the FXR/TGR5 dual agonist, INT-767, can improve renal lipid metabolism disorders and delay CKD progression. Drugs targeting mitochondrial dysfunction could be an option for the treatment of dyslipidemia and lipotoxicity, particularly in renal diseases.

Randomized, Placebo-Controlled Phase 2b Study to Evaluate the Safety and Efficacy of Recombinant Human Lecithin Cholesterol Acyltransferase in Acute ST-Segment-Elevation Myocardial Infarction: Results of REAL-TIMI 63B

BACKGROUND

High-density lipoprotein plays a key role in reverse cholesterol transport. In addition, high-density lipoprotein particles may be cardioprotective and reduce infarct size in the setting of myocardial injury. Lecithin-cholesterol acyltransferase is a rate-limiting enzyme in reverse cholesterol transport. MEDI6012 is a recombinant human lecithin-cholesterol acyltransferase that increases high-density lipoprotein cholesterol. Administration of lecithin-cholesterol acyltransferase has the potential to reduce infarct size and regress coronary plaque in acute ST-segment-elevation myocardial infarction.

METHODS

REAL-TIMI 63B (A Randomized, Placebo‑controlled Phase 2b Study to Evaluate the Safety and Efficacy of MEDI6012 in Acute ST Elevation Myocardial Infarction) was a phase 2B multinational, placebo-controlled, randomized trial. Patients with ST-segment-elevation myocardial infarction within 6 hours of symptom onset and planned for percutaneous intervention were randomly assigned 2:1 to MEDI6012 (2- or 6-dose regimen) or placebo and followed for 12 weeks. The primary outcome was infarct size as a percentage of left ventricular mass by cardiac MRI at 10 to 12 weeks, with the primary analysis in patients with TIMI Flow Grade 0 to 1 before percutaneous intervention who received at least 2 doses of MEDI6012. The secondary outcome was change in noncalcified plaque volume on coronary computed tomographic angiography from baseline to 10 to 12 weeks with the primary analysis in patients who received all 6 doses of MEDI6012.

RESULTS

A total of 593 patients were randomly assigned. Patients were a median of 62 years old, 77.9% male, and 95.8% statin naive. Median time from symptom onset to randomization was 146 (interquartile range [IQR], 103-221) minutes and from hospitalization to randomization was 12.7 (IQR, 6.6-24.0) minutes, and the first dose of drug was administered a median of 8 (IQR, 3-13) minutes before percutaneous intervention. The index myocardial infarction was anterior in 69.6% and TIMI Flow Grade 0 to 1 in 65.1% of patients. At 12 weeks, infarct size did not differ between treatment groups (MEDI6012: 9.71%, IQR 4.79-16.38; placebo: 10.48%, [IQR, 4.92-16.61], 1-sided P=0.79. There was also no difference in noncalcified plaque volume (geometric mean ratio, 0.96 [95% CI, NA-1.10], 1-sided P=0.30). There was no significant difference in treatment emergent serious adverse events.

CONCLUSIONS

Administration of MEDI6012 in patients with acute ST-segment-elevation myocardial infarction did not result in a significant reduction in infarct size or noncalcified plaque volume at 12 weeks. MEDI6012 was well tolerated with no excess in overall serious adverse events.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03578809.

HDL metabolism and functions impacting on cell cholesterol homeostasis are specifically altered in patients with abdominal aortic aneurysm

Background

The etiopathogenesis of abdominal aortic aneurysm (AAA) is still unclarified, but vascular inflammation and matrix metalloproteases activation have a recognized role in AAA development and progression. Circulating lipoproteins are involved in tissue inflammation and repair, particularly through the regulation of intracellular cholesterol, whose excess is associated to cell damage and proinflammatory activation. We analyzed lipoprotein metabolism and function in AAA and in control vasculopathic patients, to highlight possible non-atherosclerosis-related, specific abnormalities.

Methods

We measured fluorometrically serum esterified/total cholesterol ratio, as an index of lecithin-cholesterol acyltransferase (LCAT) activity, and cholesteryl ester transfer protein (CETP) activity in patients referred to vascular surgery either for AAA (n=30) or stenotic aortic/peripheral atherosclerosis (n=21) having similar burden of cardiovascular risk factors and disease. We measured high-density lipoprotein (HDL)-cholesterol efflux capacity (CEC), through the ATP-binding cassette G1 (ABCG1) and A1 (ABCA1) pathways and serum cell cholesterol loading capacity (CLC), by radioisotopic and fluorimetric methods, respectively.

Results

We found higher LCAT (+23%; p < 0.0001) and CETP (+49%; p < 0.0001) activity in AAA sera. HDL ABCG1-CEC was lower (−16%; p < 0.001) and ABCA1-CEC was higher (+31.7%; p < 0.0001) in AAA. Stratification suggests that smoking may partly contribute to these modifications. CEC and CETP activity correlated with CLC only in AAA.

Conclusions

We demonstrated that compared to patients with stenotic atherosclerosis, patients with AAA had altered HDL metabolism and functions involved in their anti-inflammatory and tissue repair activity, particularly through the ABCG1-related intracellular signaling. Clarifying the relevance of this mechanism for AAA evolution might help in developing new diagnostic parameters and therapeutic targets for the early management of this condition.

Lipid and Lipoprotein Metabolism

The exogenous lipoprotein pathway starts with the incorporation of dietary lipids into chylomicrons in the intestine. Chylomicron triglycerides are metabolized in muscle and adipose tissue and chylomicron remnants are formed, which are removed by the liver. The endogenous lipoprotein pathway begins in the liver with the formation of very low-density lipoprotein particles (VLDL). VLDL triglycerides are metabolized in muscle and adipose tissue forming intermediate-density lipoprotein (IDL), which may be taken up by the liver or further metabolized to low-density lipoprotein (LDL). Reverse cholesterol transport begins with the formation of nascent high-density lipoprotein (HDL) by the liver and intestine that acquire cholesterol from cells resulting in mature HDL. The HDL then transports the cholesterol to the liver either directly or indirectly by transferring the cholesterol to VLDL or LDL.

Screening of Prognostic Markers for Hepatocellular Carcinoma Patients Based on Multichip Combined Analysis

Methods

GSE (14520, 36376, 57957, 76427) datasets were accessed from GEO database. 55 differential mRNAs (DEGs) were obtained by differential analysis based on the datasets. GO and KEGG analysis results indicated that the DEGs were enriched in xenobiotic metabolic process and other pathways. Expression profiles and clinical data of TCGA-LIHC mRNAs were from TCGA database. We established a prognostic model of HCC through univariate and multivariate Cox risk regression analyses. ROC curve analysis was used to examine the prognostic model performance. GSEA analysis was performed between the high- and low-risk score sample groups.

Results

A 4-gene HCC prognostic model was constructed, in which the gene expressions correlated to HCC patients' survival. The AUC value presented 0.734 in the ROC analysis for the prognostic model.

Conclusion

The four-gene model could be introduced as an independent prognostic factors to assess HCC patients' survival status.

Lipidomic Approaches to Study HDL Metabolism in Patients with Central Obesity Diagnosed with Metabolic Syndrome

The metabolic syndrome (MetS) is a cluster of cardiovascular risk factors characterised by central obesity, atherogenic dyslipidaemia, and changes in the circulating lipidome; the underlying mechanisms that lead to this lipid remodelling have only been partially elucidated. This study used an integrated "omics" approach (untargeted whole serum lipidomics, targeted proteomics, and lipoprotein lipidomics) to study lipoprotein remodelling and HDL composition in subjects with central obesity diagnosed with MetS (vs. controls). Compared with healthy subjects, MetS patients showed higher free fatty acids, diglycerides, phosphatidylcholines, and triglycerides, particularly those enriched in products of de novo lipogenesis. On the other hand, the "lysophosphatidylcholines to phosphatidylcholines" and "cholesteryl ester to free cholesterol" ratios were reduced, pointing to a lower activity of lecithin cholesterol acyltransferase (LCAT) in MetS; LCAT activity (directly measured and predicted by lipidomic ratios) was positively correlated with high-density lipoprotein cholesterol (HDL-C) and negatively correlated with body mass index (BMI) and insulin resistance. Moreover, many phosphatidylcholines and sphingomyelins were significantly lower in the HDL of MetS patients and strongly correlated with BMI and clinical metabolic parameters. These results suggest that MetS is associated with an impairment of phospholipid metabolism in HDL, partially led by LCAT, and associated with obesity and underlying insulin resistance. This study proposes a candidate strategy to use integrated "omics" approaches to gain mechanistic insights into lipoprotein remodelling, thus deepening the knowledge regarding the molecular basis of the association between MetS and atherosclerosis.

LCAT- targeted therapies: Progress, failures and future

Lecithin: cholesterol acyltransferase (LCAT) is the only enzyme in plasma which is able to esterify cholesterol and boost cholesterol esterify with phospholipid-derived acyl chains. In order to better understand the progress of LCAT research, it is always inescapable that it is linked to high-density lipoprotein (HDL) metabolism and reverse cholesterol transport (RCT). Because LCAT plays a central role in HDL metabolism and RCT, many animal studies and clinical studies are currently aimed at improving plasma lipid metabolism by increasing LCAT activity in order to find better treatment options for familial LCAT deficiency (FLD), fish eye disease (FED), and cardiovascular disease. Recombinant human LCAT (rhLCAT) injections, cells and gene therapy, and small molecule activators have been carried out with promising results. Recently rhLCAT therapies have entered clinical phase II trials with good prospects. In this review, we discuss the diseases associated with LCAT and therapies that use LCAT as a target hoping to find out whether LCAT can be an effective therapeutic target for coronary heart disease and atherosclerosis. Also, probing the mechanism of action of LCAT may help better understand the heterogeneity of HDL and the action mechanism of dynamic lipoprotein particles.

Moderate alcohol consumption and lipoprotein subfractions: a systematic review of intervention and observational studies

CONTEXT

Moderate alcohol consumption is associated with decreased risk of cardiovascular disease (CVD) and improvement in cardiovascular risk markers, including lipoproteins and lipoprotein subfractions.

OBJECTIVE

To systematically review the relationship between moderate alcohol intake, lipoprotein subfractions, and related mechanisms.

DATA SOURCES

Following PRISMA, all human and ex vivo studies with an alcohol intake up to 60 g/d were included from 8 databases.

DATA EXTRACTION

A total of 17 478 studies were screened, and data were extracted from 37 intervention and 77 observational studies.

RESULTS

Alcohol intake was positively associated with all HDL subfractions. A few studies found lower levels of small LDLs, increased average LDL particle size, and nonlinear relationships to apolipoprotein B-containing lipoproteins. Cholesterol efflux capacity and paraoxonase activity were consistently increased. Several studies had unclear or high risk of bias, and heterogeneous laboratory methods restricted comparability between studies.

CONCLUSIONS

Up to 60 g/d alcohol can cause changes in lipoprotein subfractions and related mechanisms that could influence cardiovascular health.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. 98955.

Abdominal obesity negatively influences key metrics of reverse cholesterol transport

Cardiometabolic risk factors increase the risk of atherosclerotic cardiovascular disease (ASCVD), but whether these metabolic anomalies affect the anti-atherogenic function of reverse cholesterol transport (RCT) is not yet clearly known. The present study aimed to delineate if the function and maturation of high density lipoprotein (HDL) particles cross-sectionally associate with surrogate markers of ASCVD in a population comprising of different degree of cardiometabolic risk. We enrolled 131 subjects and characterized cardiometabolic risk based on the IDF criteria's for metabolic syndrome (MS). In this population, cholesterol efflux capacity (CEC), Lecithin-cholesterol acyltransferase (LCAT) and ApoA-1 glycation was associated with waist circumference, abdominal visceral fat (VFA) and abdominal subcutaneous fat. In multivariate analyses, VFA was identified as a critical contributor for low CEC and LCAT. When stratified into groups based on the presence of cardiometabolic risk factors, we found a prominent reduction in CEC and LCAT as a function of the progressive increase of cardiometabolic risk from 0-2, 0-3 to 0-4/5, whereas an increase in Pre-β-HDL and ApoA-1 glycation was observed between the lowest and highest risk groups. These findings confirm the connection between MS and its predisposing conditions to an impairment of atheroprotective efflux-promoting function of HDLs. Furthermore, we have identified the bona fide pathogenically contribution of abdominal obesity to profound alterations of key metrics of RCT.

A ten-genes-based diagnostic signature for atherosclerosis

BACKGROUND

Atherosclerosis is the leading cause of cardiovascular disease with a high mortality worldwide. Understanding the atherosclerosis pathogenesis and identification of efficient diagnostic signatures remain major problems of modern medicine. This study aims to screen the potential diagnostic genes for atherosclerosis.

METHODS

We downloaded the gene chip data of 135 peripheral blood samples, including 57 samples with atherosclerosis and 78 healthy subjects from GEO database (Accession Number: GSE20129). The weighted gene co-expression network analysis was applied to identify atherosclerosis-related genes. Functional enrichment analysis was conducted by using the clusterProfiler R package. The interaction pairs of proteins encoded by atherosclerosis-related genes were screened using STRING database, and the interaction network was further optimized with the cytoHubba plug-in of Cytoscape software.

RESULTS

The logistic regression diagnostic model was constructed to predict normal and atherosclerosis samples. A gene module which included 532 genes related to the occurrence of atherosclerosis were screened. Functional enrichment analysis basing on the 532 genes identified 235 significantly enriched GO terms and 44 significantly enriched KEGG pathways. The top 50 hub genes of the protein-protein interaction network were identified. The final logistic regression diagnostic model was established by the optimal 10 key genes, which could distinguish atherosclerosis samples from normal samples.

CONCLUSIONS

A predictive model based on 10 potential atherosclerosis-related genes was obtained, which should shed light on the diagnostic research of atherosclerosis.

Altered HDL Proteome Predicts Incident CVD in Chronic Kidney Disease Patients

Patients with chronic kidney disease (CKD) are at high risk for CVD. However, traditional lipid risk factors, including low HDL levels, cannot completely explain the increased risk. Altered HDL proteome is linked with both CVD and CKD, but the role of HDL proteins in incident CVD events in patients with CKD is unknown. In this prospective case-control study, we used targeted proteomics to quantify 31 HDL proteins in 92 subjects (46 incident new CVD and 46 one-to-one matched controls) at various stages of CKD. We tested associations of HDL proteins with incident CVD using matched logistic regression analysis. In the model fully adjusted for clinical confounders, lipid levels, C-reactive protein, and proteinuria, no significant associations were found for HDL-C, but we observed inverse associations between levels of HDL proteins paraoxonase/arylesterase 1 (PON1), paraoxonase/arylesterase 3 (PON3), and LCAT and incident CVD. Odds ratios (per 1 SD) were 0.38 (0.18–0.97, P = 0.042), 0.42 (0.20–0.92, P = 0.031), and 0.30 (0.11–0.83, P = 0.020) for PON1, PON3, and LCAT, respectively. Apolipoprotein A-IV remained associated with incident CVD in CKD patients in models adjusted for clinical confounders and lipid levels but lost significance with the addition of C-reactive protein and proteinuria to the model. In conclusion, levels of four HDL proteins, PON1, PON3, LCAT, and apolipoprotein A-IV, were found to be inversely associated with incident CVD events in CKD patients. Our observations indicate that HDLs' protein cargo, but not HDL-C levels, can serve as a marker—and perhaps mediator—for elevated CVD risk in CKD patients.

Correction of Familial LCAT Deficiency by AAV-hLCAT Prevents Renal Injury and Atherosclerosis in Hamsters-Brief Report

[Figure: see text].

Current Status of Familial LCAT Deficiency in Japan

Lecithin cholesterol acyltransferase (LCAT) is a lipid-modification enzyme that catalyzes the transfer of the acyl chain from the second position of lecithin to the hydroxyl group of cholesterol (FC) on plasma lipoproteins to form cholesteryl acylester and lysolecithin. Familial LCAT deficiency is an intractable autosomal recessive disorder caused by inherited dysfunction of the LCAT enzyme. The disease appears in two different phenotypes depending on the position of the gene mutation: familial LCAT deficiency (FLD, OMIM 245900) that lacks esterification activity on both HDL and ApoB-containing lipoproteins, and fish-eye disease (FED, OMIM 136120) that lacks activity only on HDL. Impaired metabolism of cholesterol and phospholipids due to LCAT dysfunction results in abnormal concentrations, composition and morphology of plasma lipoproteins and further causes ectopic lipid accumulation and/or abnormal lipid composition in certain tissues/cells, and serious dysfunction and complications in certain organs. Marked reduction of plasma HDL-cholesterol (HDL-C) and corneal opacity are common clinical manifestations of FLD and FED. FLD is also accompanied by anemia, proteinuria and progressive renal failure that eventually requires hemodialysis. Replacement therapy with the LCAT enzyme should prevent progression of serious complications, particularly renal dysfunction and corneal opacity. A clinical research project aiming at gene/cell therapy is currently underway.

Evaluation of lipid metabolizing enzymes: Paraxonase1 (PON1) and lecithin cholesterol acyltransferase (LCAT) activities in children with nephrotic syndrome

Background: The most common glomerular disorder in children is nephrotic syndrome, associated with high morbidity despite notable advances in its treatment. Many of the nephrotic syndrome complications, including the increased risk of atherosclerosis and thromboembolism, can be linked to dysregulated lipid metabolism and dyslipidemia. Paraoxonase enzyme is responsible for the most of the antioxidant properties of HDL, thus preventing the formation of atherogenic ox-LDL molecules, and lecithin cholesterol acyltransferase is intimately involved in HDL maturation and is a key component of the reverse cholesterol transport pathway, which removes excess cholesterol molecules from the peripheral tissues to the liver for excretion. Objectives: The present study aimed to investigate the serum activities of paraoxonase-1 (PON-1) and lecithin cholesterol acyltransferase (LCAT) in children with nephrotic syndrome in an active phase (as newly diagnosed or old cases with acute relapse). Also, to study any correlation exists between paraoxonase-1 activity and lipid profile. Methods: This study consists of group 1 with 40 cases of nephrotic syndrome in the age group of (2-14 years) and group 2 with 40 age and sex-matched healthy controls. Lipid profile and paraoxonase activity, lecithin cholesterol acyltransferase activities were measured in both groups’ serum samples. Results: Statistical analysis of student’s t-test showed that the mean levels of total cholesterol, triglycerides, LDL were significantly increased in group 1 when compared to Group 2 (p <0.001). PON1 and lecithin cholesterol acyltransferase levels were significantly lower in group 1 compared to group 2, and there is no significant difference among nephrotic groups. Conclusions: Both paraoxonase-1 enzyme and lecithin cholesterol acyltransferase are considered good promising predictors for nephrotic syndrome and other parameters such as LDL, HDL, and TG. The significantly decreased paraoxonase-1 enzyme and lecithin cholesterol acyltransferase activities result in increased oxidation of LDL, thus accelerating atherosclerosis.

Revealing the Role of High-Density Lipoprotein in Colorectal Cancer

Colorectal cancer (CRC) is a highly prevalent malignancy with multifactorial etiology, which includes metabolic alterations as contributors to disease development. Studies have shown that lipid status disorders are involved in colorectal carcinogenesis. In line with this, previous studies have also suggested that the serum high-density lipoprotein cholesterol (HDL-C) level decreases in patients with CRC, but more recently, the focus of investigations has shifted toward the exploration of qualitative properties of HDL in this malignancy. Herein, a comprehensive overview of available evidences regarding the putative role of HDL in CRC will be presented. We will analyze existing findings regarding alterations of HDL-C levels but also HDL particle structure and distribution in CRC. In addition, changes in HDL functionality in this malignancy will be discussed. Moreover, we will focus on the genetic regulation of HDL metabolism, as well as the involvement of HDL in disturbances of cholesterol trafficking in CRC. Finally, possible therapeutic implications related to HDL will be presented. Given the available evidence, future studies are needed to resolve all raised issues concerning the suggested protective role of HDL in CRC, its presumed function as a biomarker, and eventual therapeutic approaches based on HDL.

High Density Lipoprotein Cholesterol Efflux Capacity and Atherosclerosis in Cardiovascular Disease: Pathophysiological Aspects and Pharmacological Perspectives

Over the years, the relationship between high-density lipoprotein (HDL) and atherosclerosis, initially highlighted by the Framingham study, has been revealed to be extremely complex, due to the multiple HDL functions involved in atheroprotection. Among them, HDL cholesterol efflux capacity (CEC), the ability of HDL to promote cell cholesterol efflux from cells, has emerged as a better predictor of cardiovascular (CV) risk compared to merely plasma HDL-cholesterol (HDL-C) levels. HDL CEC is impaired in many genetic and pathological conditions associated to high CV risk such as dyslipidemia, chronic kidney disease, diabetes, inflammatory and autoimmune diseases, endocrine disorders, etc. The present review describes the current knowledge on HDL CEC modifications in these conditions, focusing on the most recent human studies and on genetic and pathophysiologic aspects. In addition, the most relevant strategies possibly modulating HDL CEC, including lifestyle modifications, as well as nutraceutical and pharmacological interventions, will be discussed. The objective of this review is to help understanding whether, from the current evidence, HDL CEC may be considered as a valid biomarker of CV risk and a potential pharmacological target for novel therapeutic approaches.

Recombinant human Lecithin-Cholesterol acyltransferase in patients with atherosclerosis: Phase 2a primary results and phase 2b design

BACKGROUND

Reverse cholesterol transport (RCT) removes cholesterol and stabilizes vulnerable plaques. In addition, high-density lipoprotein (HDL) may be cardioprotective in acute MI. Lecithin-cholesterol acyltransferase (LCAT) may enhance RCT. The objective of this study was to investigate the pharmacokinetics, pharmacodynamics, and safety of multiple ascending doses of recombinant human LCAT (MEDI6012) to inform a Phase 2 b program.

METHODS

This was a randomized, blinded, placebo-controlled, dose-escalation Phase 2a study of MEDI6012. Patients were randomized into 1 of 4 cohorts (40, 120, 300 mg IV weekly x3 doses, or 300 mg IV-push, 150 mg at 48-hours and 100 mg at 7 days). All cohorts were planned to randomize 6:2 (MEDI6012 vs placebo). The primary endpoints were baseline-adjusted AUC from 0-96 hours post dose-3 (AUC0-96hr) for HDL-C, HDL cholesteryl ester (HDL-CE), and total cholesteryl ester (CE). The primary safety endpoints were treatment-emergent adverse events (AEs).

RESULTS

A total of 32 patients were randomized. MEDI6012 significantly increased AUC0-96hr for HDL-C, HDL-CE and CE in a graded fashion with increasing doses. Relative to placebo, MEDI6012 increased HDL-C at Day 19 by 66% (95%CI 33-99, p = 0.014) with 120 mg and 144% (95%CI 108-181, p < 0.001) with 300 mg. An IV-push increased HDL-C by 40.8% at 30 minutes. Overall AEs were similar between groups with no severe, life-threatening/fatal AEs or neutralizing antibodies.

CONCLUSIONS

Multiple ascending doses of MEDI6012 were safe and well tolerated and significantly increased HDL-C, HDL-CE and CE in a dose-related manner. These data support the ongoing Phase 2 b program investigating MEDI6012 in ST-elevation MI.

Novel LCAT (Lecithin:Cholesterol Acyltransferase) Activator DS-8190a Prevents the Progression of Plaque Accumulation in Atherosclerosis Models

OBJECTIVE

Enhancement of LCAT (lecithin:cholesterol acyltransferase) activity has possibility to be beneficial for atherosclerosis. To evaluate this concept, we characterized our novel, orally administered, small-molecule LCAT activator DS-8190a, which was created from high-throughput screening and subsequent derivatization. We also focused on its mechanism of LCAT activation and the therapeutic activity with improvement of HDL (high-density lipoprotein) functionality. Approach and Results: DS-8190a activated human and cynomolgus monkey but not mouse LCAT enzymes in vitro. DS-8190a was orally administered to cynomolgus monkeys and dose dependently increased LCAT activity (2.0-fold in 3 mg/kg group on day 7), resulting in HDL cholesterol elevation without drastic changes of non-HDL cholesterol. Atheroprotective effects were then evaluated using Ldl-r KO×hLcat Tg mice fed a Western diet for 8 weeks. DS-8190a treatment achieved significant reduction of atherosclerotic lesion area (48.3% reduction in 10 mg/kg treatment group). Furthermore, we conducted reverse cholesterol transport study using Ldl-r KO×hLcat Tg mice intraperitoneally injected with J774A.1 cells loaded with [3H]-cholesterol and confirmed significant increases of [3H] count in plasma (1.4-fold) and feces (1.4-fold on day 2 and 1.5-fold on day3) in the DS-8190a-treated group. With regard to the molecular mechanism involved, direct binding of DS-8190a to human LCAT protein was confirmed by 2 different approaches: affinity purification by DS-8190a-immobilized beads and thermal shift assay. In addition, the candidate binding site of DS-8190a in human LCAT protein was identified by photoaffinity labeling.

CONCLUSIONS

This study demonstrates the potential of DS-8190a as a novel therapeutic for atherosclerosis. In addition, this compound proves that a small-molecule direct LCAT activator can achieve HDL-C elevation in monkey and reduction of atherosclerotic lesion area with enhanced HDL function in rodent.

High-Density Lipoprotein Modifications: A Pathological Consequence or Cause of Disease Progression?

High-density lipoprotein (HDL) is well-known for its cardioprotective effects, as it possesses anti-inflammatory, anti-oxidative, anti-thrombotic, and cytoprotective properties. Traditionally, studies and therapeutic approaches have focused on raising HDL cholesterol levels. Recently, it became evident that, not HDL cholesterol, but HDL composition and functionality, is probably a more fruitful target. In disorders, such as chronic kidney disease or cardiovascular diseases, it has been observed that HDL is modified and becomes dysfunctional. There are different modification that can occur, such as serum amyloid, an enrichment and oxidation, carbamylation, and glycation of key proteins. Additionally, the composition of HDL can be affected by changes to enzymes such as cholesterol ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), and phospholipid transfer protein (PLTP) or by modification to other important components. This review will highlight some main modifications to HDL and discuss whether these modifications are purely a consequential result of pathology or are actually involved in the pathology itself and have a causal role. Therefore, HDL composition may present a molecular target for the amelioration of certain diseases, but more information is needed to determine to what extent HDL modifications play a causal role in disease development.

Effect of polyphenol, flavonoid, and saponin fractions from Thymus atlanticus on acute and chronic hyperlipidemia in mice

Background

Thymus atlanticus is an endemic plant of the Mediterranean region, which has been used in the Moroccan mountain area to treat several diseases. This study aimed to investigate the effect of polyphenol, flavonoid, and saponin fractions derived from this plant on acute and chronic hyperlipidemia in male albino mice.

Results

The results indicated that the injection of Triton WR-1339 (20 mg/100 g body weight (B.wt.)) and 6-week administration of a high-fat diet (which is an 81.8% standard diet supplemented with 2% cholesterol, 16% lard, and 0.2% cholic acid) significantly increased plasma total cholesterol, triglycerides and low-density lipoprotein cholesterol (LDL-C), but did not affect high-density lipoprotein cholesterol (HDL-C) levels in mice. Administration of a single dose (2 mg/kg B.wt.) of polyphenol, flavonoid, or saponin fractions significantly suppressed the effect of Triton injection on plasma total cholesterol, triglycerides, and LDL-C. In addition, the supplementation of the high-fat diet with polyphenol fraction (2 mg/kg B.wt./day) prevented the increase of total cholesterol, triglycerides, and LDL-C, and effectively increased HDL-C level when compared to mice feeding only the high-fat diet.

Conclusion

In conclusion, phenolic compounds from Thymus atlanticus possess a significant hypocholesterolemic and hypotriglyceridemic effects and, therefore, could have an important role in the management of dyslipidemia.

The effects of exercise training on lipid metabolism and coronary heart disease

Blood lipoproteins are formed by various amounts of cholesterol (C), triglycerides (TGs), phospholipids, and apolipoproteins (Apos). ApoA1 is the major structural protein of high-density lipoprotein (HDL), accounting for ~70% of HDL protein, and mediates many of the antiatherogenic functions of HDL. Conversely, ApoB is the predominant low-density lipoprotein (LDL) Apo and is an indicator of circulating LDL, associated with higher coronary heart disease (CHD) risk. Thus, the ratio of ApoB to ApoA1 (ApoB/ApoA1) is used as a surrogate marker of the risk of CHD related to lipoproteins. Elevated or abnormal levels of lipids and/or lipoproteins in the blood are a significant CHD risk factor, and several studies support the idea that aerobic exercise decreases CHD risk by partially lowering serum TG and LDL-cholesterol (LDL-C) levels and increasing HDL-C levels. Exercise also exerts an effect on HDL-C maturation and composition and on reverse C transport from peripheral cells to the liver to favor its catabolism and excretion. This process prevents atherosclerosis, and several studies showed that exercise training increases heart lipid metabolism and protects against cardiovascular disease. In these and other ways, it more and more appears that regular exercise, nutrition, and strategies to modulate lipid profile should be viewed as an integrated whole. The purpose of this review is to assess the effects of endurance training on the nontraditional lipid biomarkers, including ApoB, ApoA1, and ApoB/ApoA1, in CHD risk.

The APOA1bp-SREBF-NOTCH axis is associated with reduced atherosclerosis risk in morbidly obese patients

BACKGROUND & AIMS

Atherosclerosis is characterized by an inflammatory disease linked to excessive lipid accumulation in the artery wall. The Notch signalling pathway has been shown to play a key regulatory role in the regulation of inflammation. Recently, in vitro and pre-clinical studies have shown that apolipoprotein A-I binding protein (AIBP) regulates cholesterol metabolism (SREBP) and NOTCH signalling (haematopoiesis) and may be protective against atherosclerosis, but the evidence in humans is scarce.

METHODS

We evaluated the APOA1bp-SREBF-NOTCH axis in association with atherosclerosis in two well-characterized cohorts of morbidly obese patients (n = 78) within the FLORINASH study, including liver transcriptomics, ¹H NMR plasma metabolomics, high-resolution ultrasonography evaluating carotid intima-media thickness (cIMT), and haematological parameters.

RESULTS

The liver expression levels of APOA1bp were associated with lower cIMT and leukocyte counts, a better plasma lipid profile and higher circulating levels of metabolites associated with lower risk of atherosclerosis (glycine, histidine and asparagine). Conversely, liver SREBF and NOTCH mRNAs were positively associated with atherosclerosis, liver steatosis, an unfavourable lipid profile, higher leukocytes and increased levels of metabolites linked to inflammation and CVD such as branched-chain amino acids and glycoproteins. APOA1bp and NOTCH signalling also had a strong association, as revealed by the negative correlations among APOA1bp expression levels and those of all NOTCH receptors and jagged ligands.

CONCLUSIONS

We here provide the first evidence in human liver of the putative APOA1bp-SREBF-NOTCH axis signalling pathway and its association with atherosclerosis and inflammation.

Anabolic androgenic steroids exert a selective remodeling of the plasma lipidome that mirrors the decrease of the de novo lipogenesis in the liver

INTRODUCTION

The abuse of anabolic androgenic steroids (AASs) is a source of public concern because of their adverse effects. Supratherapeutic doses of AASs are known to be hepatotoxic and regulate the lipoproteins in plasma by modifying the metabolism of lipids in the liver, which is associated with metabolic diseases. However, the effect of AASs on the profile of lipids in plasma is unknown.

OBJECTIVES

To describe the changes in the plasma lipidome exerted by AASs and to discuss these changes in the light of previous research about AASs and de novo lipogenesis in the liver.

METHODS

We treated male Wistar rats with supratherapeutic doses of nandrolone decanoate and testosterone undecanoate. Subsequently, we isolated the blood plasma and performed lipidomics analysis by liquid chromatography-high resolution mass spectrometry.

RESULTS

Lipid profiling revealed a decrease of sphingolipids and glycerolipids with palmitic, palmitoleic, stearic, and oleic acids. In addition, lipid profiling revealed an increase in free fatty acids and glycerophospholipids with odd-numbered chain fatty acids and/or arachidonic acid.

CONCLUSION

The lipid profile presented herein reports the imprint of AASs on the plasma lipidome, which mirrors the downregulation of de novo lipogenesis in the liver. In a broader perspective, this profile will help to understand the influence of androgens on the lipid metabolism in future studies of diseases with dysregulated lipogenesis (e.g. type 2 diabetes, fatty liver disease, and hepatocellular carcinoma).

An Updated Review of Lysophosphatidylcholine Metabolism in Human Diseases

Lysophosphatidylcholine (LPC) is increasingly recognized as a key marker/factor positively associated with cardiovascular and neurodegenerative diseases. However, findings from recent clinical lipidomic studies of LPC have been controversial. A key issue is the complexity of the enzymatic cascade involved in LPC metabolism. Here, we address the coordination of these enzymes and the derangement that may disrupt LPC homeostasis, leading to metabolic disorders. LPC is mainly derived from the turnover of phosphatidylcholine (PC) in the circulation by phospholipase A₂ (PLA₂). In the presence of Acyl-CoA, lysophosphatidylcholine acyltransferase (LPCAT) converts LPC to PC, which rapidly gets recycled by the Lands cycle. However, overexpression or enhanced activity of PLA₂ increases the LPC content in modified low-density lipoprotein (LDL) and oxidized LDL, which play significant roles in the development of atherosclerotic plaques and endothelial dysfunction. The intracellular enzyme LPCAT cannot directly remove LPC from circulation. Hydrolysis of LPC by autotaxin, an enzyme with lysophospholipase D activity, generates lysophosphatidic acid, which is highly associated with cancers. Although enzymes with lysophospholipase A₁ activity could theoretically degrade LPC into harmless metabolites, they have not been found in the circulation. In conclusion, understanding enzyme kinetics and LPC metabolism may help identify novel therapeutic targets in LPC-associated diseases.

Association of lecithin-cholesterol acyltransferase activity and low-density lipoprotein heterogeneity with atherosclerotic cardiovascular disease risk: a longitudinal pilot study

BACKGROUND

Lecithin-cholesterol acyltransferase (LCAT) is believed to be involved in reverse cholesterol transport, which is known to play a key role in suppression of atherosclerosis. However, recent investigations have demonstrated that higher LCAT activity, measured in terms of the serum cholesterol esterification rate by an endogenous substrate method, is associated with increased formation of triglyceride (TG)-rich lipoproteins (TRLs), leading to a decrease in the low-density lipoprotein (LDL) particle size. The purpose of this hospital-based longitudinal study was to clarify the causal relationship between changes in the LCAT activity and changes in the LDL-particle size.

METHODS

The subjects were a total of 335 patients, derived from our previous study cohort, with one or more risk factors for atherosclerotic cardiovascular disease (ASCVD). For this study, we measured the LDL-particle size (relative LDL migration [LDL-Rm value]) by polyacrylamide gel electrophoresis in the subjects, along with the changes in the LCAT activity, at the end of a follow-up period of at least 1 year.

RESULTS

The results revealed that the absolute change (Δ) in the LDL-particle size increased significantly as the quartile of Δ LCAT activity increased (p = 0.01). A multi-logistic regression adjusted-analysis revealed that Δ LCAT activity in the fourth quartile as compared to that in the first quartile was independently predictive of an increased LDL-particle size (odds ratio [95% confidence interval]: 2.03 [1.02/4.04], p = 0.04). Moreover, the ∆ LCAT activity was also positively correlated with ∆ TRL-related markers (i.e., TG, remnant particle-like cholesterol [RLP-C], apolipoprotein B, apolipoprotein C-2, and apolipoprotein C-3).

CONCLUSIONS

The results lend support to the hypothesis that increased LCAT activity may be associated with increased formation of TRLs, leading to a reduction in the LDL-particle size in patients at a high risk for ASCVD. To reduce the risk of ASCVD, it may be important to focus not only on the quantitative changes in the serum LDL-cholesterol levels, but also on the LCAT activity.

TRIAL REGISTRATION

UMIN ( https://upload.umin.ac.jp/cgi-bin/ctr/ctr_reg_list.cgi ) Study ID: UMIN000033228 retrospectively registered 2 July 2018.

Changes in lecithin: cholesterol acyltransferase, cholesteryl ester transfer protein and paraoxonase-1 activities in patients with colorectal cancer

BACKGROUND

Previous studies revealed decreased level of high-density lipoprotein cholesterol (HDLC) as important factor for development of colorectal cancer (CRC). Quantity and structure of HDL particles depend on activities of lipid transfer proteins lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP), but this topic is largely unexplored in CRC. The main objective of this study was to investigate activities of LCAT and CETP in patients with CRC. Additionally, we analyzed activity of paraoxonase-1 (PON-1), as a main carrier of HDL-antioxidant function.

MATERIALS AND METHODS

Ninety-nine CRC patients and 101 healthy individuals were included. LCAT and CETP activities were assessed by measuring rates of formation and transfer of cholesteryl esters. PON-1 paraoxonase and arylesterase activities were measured.

RESULTS

Lower levels of HDL-C (p < .001) were observed in cohort of patients, alongside with decreased LCAT (p < .050) and increased CETP activity (p < .050). Both PON-1 activities were diminished in CRC (p < .050 and p < .001 respectively). Univariate logistic regression singled out HDL-C level (OR = 0.218, p < .001), CETP activity (OR = 1.010, p < .01) and mass (OR = 0.994, p < .001) as possible markers of elevated CRC risk. CETP mass maintained its predictive significance when adjusted for traditional risk factors and level of oxidative stress (OR = 0.993, p < .001; OR = 0.982, p < .050, respectively).

CONCLUSION

Our results demonstrated increased CETP and decreased LCAT and PON-1 activities in CRC patients. In preliminary analysis CETP mass was identified as potential significant predictor of CRC development, suggesting that alterations in HDL-C levels, alongside with changes in HDL structure might have a role in carcinogenesis.

Cholesterol is Inefficiently Converted to Cholesteryl Esters in the Blood of Cardiovascular Disease Patients

Shotgun lipidomic analysis of 203 lipids in 13 lipid classes performed on blood plasma of donors who had just suffered an acute coronary syndrome (ACS, n = 74), or an ischemic stroke (IS, n = 21), or who suffer from stable angina pectoris (SAP, n = 78), and an age-matched control cohort (n = 52), showed some of the highest inter-lipid class correlations between cholesteryl esters (CE) and phosphatidylcholines (PC) sharing a common fatty acid. The concentration of lysophospatidylcholine (LPC) and ratios of concentrations of CE to free cholesterol (Chol) were also lower in the CVD cohorts than in the control cohort, indicating a deficient conversion of Chol to CE in the blood plasma in the CVD subjects. A non-equilibrium reaction quotient, Q′, describing the global homeostasis of cholesterol as manifested in the blood plasma was shown to have a value in the CVD cohorts (Q′_ACS = 0.217 ± 0.084; Q′_IS = 0.201 ± 0.084; Q′_SAP = 0.220 ± 0.071) that was about one third less than in the control cohort (Q′_Control = 0.320 ± 0.095, p < 1 × 10⁻⁴), suggesting its potential use as a rapid predictive/diagnostic measure of CVD-related irregularities in cholesterol homeostasis.

Paradoxical fall in proteinuria during pregnancy in an LCAT-deficient patient-A case report

A 29-year-old lady was diagnosed with lecithin:cholesterol acyltransferase (LCAT) deficiency having presented with bilateral corneal clouding, severely reduced high density lipoproteins cholesterol, and proteinuria. She is a compound heterozygote with two LCAT gene mutations, one of which is novel, c.321C>A in exon 3. Surprisingly, the level of proteinuria significantly improved during pregnancy, despite stopping the angiotensin-converting enzyme inhibitor. However, LCAT concentration and activity remained identical during pregnancy and postpartum. Her pregnancy was complicated by rising triglyceride levels from the second trimester requiring treatment with omega-3 fatty acid and fenofibrate. In the last trimester, a further complication arose when she became hypertensive and proteinuria worsened. She was diagnosed with pre-eclampsia and had an emergency cesarean section at 39 weeks delivering a healthy baby. This case adds to the knowledge of the pathophysiology of LCAT deficiency during pregnancy and will be useful in future patient management.

Comparative omics and feeding manipulations in chicken indicate a shift of the endocrine role of visceral fat towards reproduction

Background

The mammalian adipose tissue plays a central role in energy-balance control, whereas the avian visceral fat hardly expresses leptin, the key adipokine in mammals. Therefore, to assess the endocrine role of adipose tissue in birds, we compared the transcriptome and proteome between two metabolically different types of chickens, broilers and layers, bred towards efficient meat and egg production, respectively.

Results

Broilers and layer hens, grown up to sexual maturation under free-feeding conditions, differed 4.0-fold in weight and 1.6-fold in ovarian-follicle counts, yet the relative accumulation of visceral fat was comparable. RNA-seq and mass-spectrometry (MS) analyses of visceral fat revealed differentially expressed genes between broilers and layers, 1106 at the mRNA level (FDR ≤ 0.05), and 203 at the protein level (P ≤ 0.05). In broilers, Ingenuity Pathway Analysis revealed activation of the PTEN-pathway, and in layers increased response to external signals. The expression pattern of genes encoding fat-secreted proteins in broilers and layers was characterized in the RNA-seq and MS data, as well as by qPCR on visceral fat under free feeding and 24 h-feed deprivation. This characterization was expanded using available RNA-seq data of tissues from red junglefowl, and of visceral fat from broilers of different types. These comparisons revealed expression of new adipokines and secreted proteins (LCAT, LECT2, SERPINE2, SFTP1, ZP1, ZP3, APOV1, VTG1 and VTG2) at the mRNA and/or protein levels, with dynamic gene expression patterns in the selected chicken lines (except for ZP1; FDR/P ≤ 0.05) and feed deprivation (NAMPT, SFTPA1 and ZP3) (P ≤ 0.05). In contrast, some of the most prominent adipokines in mammals, leptin, TNF, IFNG, and IL6 were expressed at a low level (FPKM/RPKM< 1) and did not show differential mRNA expression neither between broiler and layer lines nor between fed vs. feed-deprived chickens.

Conclusions

Our study revealed that RNA and protein expression in visceral fat changes with selective breeding, suggesting endocrine roles of visceral fat in the selected phenotypes. In comparison to gene expression in visceral fat of mammals, our findings points to a more direct cross talk of the chicken visceral fat with the reproductive system and lower involvement in the regulation of appetite, inflammation and insulin resistance.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4675-0) contains supplementary material, which is available to authorized users.

Novel metabolic phenotypes in lecithin cholesterol acyltyransferase-deficient mice

PURPOSE OF REVIEW

Lecithin cholesterol acyltyransferase (LCAT) deficiency is a rare monogenic disorder causing lipoprotein dysregulation and multiple organ dysfunctions, including renal impairment. LCAT knockout mice have been shown informative in elucidating mechanisms of many major clinical morbid phenotypes. Extended characterization of the LDL receptor/LCAT double knockout (Ldlr/Lcat-DKO or DKO) mice had led to the discovery of a number of novel protective metabolic phenotypes, including resistance to obesity, nonalcoholic steatohepatitis (NASH) and insulin resistance. We seek to integrate the findings to explore novel pathogenic pathways.

RECENT FINDINGS

The chow fed DKO mice were found more insulin sensitive than their Ldlr-KO controls. Joint analyses of the three strains (DKO, Ldlr-KO and wild-type) revealed differential metabolic responses to a high cholesterol diet (HCD) vs. high-fat diet (HFD). DKO mice are protected from HFD-induced obesity, hepatic endoplasmic reticulum (ER) stress, insulin resistance, ER cholesterol and NASH markers (steatosis and inflammasomes). Joint analysis revealed the HFD-induced NASH is dependent on de-novo hepatic cholesterol biosynthesis. DKO mice are protected from HCD-induced hepatic ER stress, ER cholesterol, but not NASH, the latter likely due to cholesterol crystal accumulation. DKO mice were found to develop ectopic brown adipose tissue (BAT) in skeletal muscle. Ectopic BAT derived in part from myoblast in utero and from adult satellite cells. Primed expression of PRDM16 and UCP in quiescent satellite cell caused by LCAT deficiency synergizes with cell cholesterol depletion to induce satellite cell-to-BAT transdifferentiation.

SUMMARY

Metabolic phenotyping of selective LCAT null mice led to the discovery of novel metabolically protective pathways.

Development of a novel fluorescent activity assay for lecithin:cholesterol acyltransferase

Background Lecithin:cholesterol acyltransferase (LCAT) is a plasma enzyme that esterifies cholesterol. Recombinant human LCAT (rhLCAT) is now being developed as an enzyme replacement therapy for familial LCAT deficiency and as a possible treatment for acute coronary syndrome. The current 'gold standard' assay for LCAT activity involves the use of radioisotopes, thus making it difficult for routine clinical use. Methods We have developed a novel and more convenient LCAT activity assay using fluorescence-labelled cholesterol (BODIPY-cholesterol), which is incorporated into proteoliposomes as a substrate instead of radiolabelled cholesterol. Results The apparent K_m and V_max were 31.5  µmol/L and 55.8 nmol/h/nmoL, rhLCAT, respectively, for the ³H-cholesterol method and 103.1  µmol/L and 13.4 nmol/h/nmol rhLCAT, respectively, for the BODIPY-cholesterol method. Although the two assays differed in their absolute units of LCAT activity, there was a good correlation between the two test assays ( r = 0.849, P < 1.6 × 10^-7, y = 0.1378x + 1.106). The BODIPY-cholesterol assay had an intra-assay CV of 13.7%, which was superior to the intra-assay CV of 20.8% for the radioisotopic assay. The proteoliposome substrate made with BODIPY-cholesterol was stable to storage for at least 10 months. The reference range ( n = 20) for the fluorescent LCAT activity assay was 4.6-24.1 U/mL/h in healthy subjects. Conclusions In summary, a novel fluorescent LCAT activity assay that utilizes BODIPY-cholesterol as a substrate is described that yields comparable results to the radioisotopic method.

HDL functionality in type 1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by absence of insulin secretion due to destruction of the pancreatic beta-cells. Patients with T1D exhibit an increased risk for cardiovascular disease (CVD) compared with non-diabetic subjects. It has been established that low concentration of high-density lipoprotein cholesterol (HDL-C), an independent risk marker of CVD, coincides with a reduced protective capacity against oxidative stress. However, conflicting results have been reported on the prevalence of low HDL-C levels in T1D. Interestingly, changes in composition and function of HDL particles (abnormal ratio of cholesteryl ester-to-triglyceride, reduction in the phospholipid content, reduced capacity to promote cholesterol efflux from macrophages, impaired anti-inflammatory and anti-oxidant activities) have been described in patients with T1D. Hence, exploring HDL function, even in the presence of normal HDL-C levels, might provide additional insight into the underlying pathophysiology associated with increased CV risk in T1D. In the current review, we will provide a detailed overview of the current evidence for a role of HDL function as independent risk factor for the development of CVD in T1D.

Fractional esterification rate of cholesterol in high-density lipoprotein associates with risk of coronary heart disease

Background

Fractional esterification rate of cholesterol in high-density lipoprotein (FER_HDL) has been found to be closely correlated with atherosclerotic dyslipidemia, especially lipoprotein distributions, and is a potentially useful predictor for coronary heart disease (CHD). The associations of FER_HDL, measured by the simple and precise HPLC method, with angiographically defined CHD and its related risk factors in Chinese patients were evaluated.

Methods

Two hundred and fifty eight Chinese patients who had indications for angiography were enrolled in this study. Coronary angiograms were obtained by the standard techniques. FER_HDL was determined by the HPLC method. Cholesterol levels in serum HDL, LDL and subfractions were measured by ultracentrifugation/HPLC method. Associations between FER_HDL and CHD and CHD risk factors were analyzed.

Results

FER_HDL was correlated with almost all the CHD risk factors. Compared with the non-CHD group, the CHD patients had higher values of FER_HDL (20.9 ± 7.9%/h vs 17.7 ± 7.1%/h, p = 0.001). FER_HDL was found to be independently and positively correlated with log TG (β = 0.386, P < 0.001) and log (LDLb-C) (β = 0.165, P = 0.020), respectively, and negatively correlated with log (HDL2-C)(β = −0.351, P < 0.001). Logistic regression analysis demonstrated that age, diabetes mellitus, smoking and FER_HDL (OR = 1.056–1.080, p < 0.05) were independent risk factors for CHD.

Conclusion

FER_HDL significantly correlated with both HDL2-C and LDLb-C, and therefore, is the predictor of lipoprotein distributions. In addition, after correcting for the presence of classic risk factors, FER_HDL was independently associated with the presence of angiographically defined CHD.

Effect of tofacitinib on lipid levels and lipid-related parameters in patients with moderate to severe psoriasis

BACKGROUND

Psoriasis is a systemic inflammatory disease associated with increased cardiovascular (CV) risk and altered lipid metabolism. Tofacitinib is an oral Janus kinase inhibitor.

OBJECTIVE

The aim of the study was to investigate the effects of tofacitinib on traditional and nontraditional lipid parameters and CV risk markers in patients with psoriasis from a phase III study, OPT Pivotal 1.

METHODS

Patients with psoriasis were randomized to tofacitinib 5 or 10 mg twice daily (BID) or placebo BID. Serum samples were collected at baseline, week 4, and week 16. Analyses included serum cholesterol levels, triglycerides, lipoproteins, lipid particles, lipid-related parameters/CV risk markers, and high-density lipoprotein (HDL) function analyses.

RESULTS

At week 16, small concurrent increases in mean low-density lipoprotein cholesterol (LDL-C) and HDL cholesterol (HDL-C) levels were observed with tofacitinib; total cholesterol/HDL-C ratio did not change. There was no significant change in the number of small dense LDL particles, which are considered to be more atherogenic than large particles, and oxidized LDL did not increase. Paraoxonase 1 activity, linked to HDL antioxidant capacity, increased, and HDL-associated serum amyloid A, which reduces the anti-atherogenic potential of HDL, decreased. HDL capacity to promote cholesterol efflux from macrophages did not change. Lecithin-cholesterol acyltransferase activity, which is associated with reverse cholesterol transport, increased. Markers of systemic inflammation, serum amyloid A and C-reactive protein, decreased with tofacitinib.

CONCLUSION

While small increases in lipid levels are observed with tofacitinib treatment in patients with psoriasis, effects on selected lipid-related parameters and other circulating CV risk biomarkers are not suggestive of an increased CV risk [NCT01276639].

Changes in apolipoprotein E-containing high-density lipoprotein (HDL) have little impact on HDL-cholesterol measurements using homogeneous assays in normolipidemic and dyslipidemic subjects

BACKGROUND

High-density lipoprotein-cholesterol (HDL-C) is generally measured using several homogeneous assays. We aimed to clarify whether apolipoprotein E-containing HDL (apoE-HDL) subfractions are altered during storage, and if so, whether such changes affect the HDL-C concentration measured using homogeneous assays.

METHODS

We stored serum from normolipidemic (n=32) and dyslipidemic (n=17) subjects at 4°C for up to 7days. ApoE-HDL subfractions were analyzed using native 2-dimensional gel (native 2D-gel) electrophoresis. HDL-C concentrations were determined using 2 precipitation and 4homogeneous assays.

RESULTS

Native 2D-gel electrophoresis revealed variously sized apoE-HDL subfractions. After 4h incubation at 37°C, subfractions of smaller particles were converted into larger particles by lecithin:cholesterol acyltransferase (LCAT) activity. After 7days storage at 4°C, the smaller subfractions were decreased in the normolipidemic group, accompanying increases in larger subfractions, whereas changes in the respective subfractions varied among individuals in the dyslipidemic group. HDL-C concentrations were significantly lower after storage at 4°C in all assays, except that using Sekisui Medical's reagent. Therefore, changes in HDL-C concentration and apoE-HDL subfractions were independent of each other.

CONCLUSION

ApoE-HDL subfractions change during storage, but these changes are not linked to those in HDL-C concentration measured using homogeneous assays.

Atherogenic Impact of Lecithin-Cholesterol Acyltransferase and Its Relation to Cholesterol Esterification Rate in HDL (FERHDL) and AIP [log(TG/HDL-C)] Biomarkers: The Butterfly Effect?

The atherogenic impact and functional capacity of LCAT was studied and discussed over a half century. This review aims to clarify the key points that may affect the final decision on whether LCAT is an anti-atherogenic or atherogenic factor. There are three main processes involving the efflux of free cholesterol from peripheral cells, LCAT action in intravascular pool where cholesterol esterification rate is under the control of HDL, LDL and VLDL subpopulations, and finally the destination of newly produced cholesteryl esters either to the catabolism in liver or to a futile cycle with apoB lipoproteins. The functionality of LCAT substantially depends on its mass together with the composition of the phospholipid bilayer as well as the saturation and the length of fatty acyls and other effectors about which we know yet nothing. Over the years, LCAT puzzle has been significantly supplemented but yet not so satisfactory as to enable how to manipulate LCAT in order to prevent cardiometabolic events. It reminds the butterfly effect when only a moderate change in the process of transformation free cholesterol to cholesteryl esters may cause a crucial turn in the intended target. On the other hand, two biomarkers – FERHDL (fractional esterification rate in HDL) and AIP [log(TG/HDL-C)] can offer a benefit to identify the risk of cardiovascular disease (CVD). They both reflect the rate of cholesterol esterification by LCAT and the composition of lipoprotein subpopulations that controls this rate. In clinical practice, AIP can be calculated from the routine lipid profile with help of AIP calculator www.biomed.cas.cz/fgu/aip/calculator.php.