Effect of ACAT inhibition on the progression of coronary atherosclerosis

Discovery of selective ACAT2 antagonist via a combination strategy based on deep docking, pharmacophore modelling, and molecular dynamics simulation

Acyl-CoA: cholesterol acyltransferase (ACAT), a pivotal enzyme in the absorption and metabolism of cholesterol, is primarily responsible for intracellular esterification. ACAT inhibition is expected to diminish plasma lipid levels by impeding intestinal cholesterol absorption, thereby preventing the progression of atherosclerotic lesions. A previous study shows that selective inhibition of ACAT2 significantly mitigated hypercholesterolaemia and atherosclerosis in mouse models. Therefore, the need for ACAT2 selective inhibitors becomes particularly urgent. In this study, we established a multilayer virtual screening workflow and subjected biologically evaluated representative compounds to enzyme inhibitory assays. The experimental results indicated that the two compounds, STL565001 (inhibition rate at 25 μM: 75.7 ± 27.8%, selectivity = 6) and STL528213 (inhibition rate at 25 μM: 87.8 ± 12.4%, selectivity = 13), demonstrated robust activity against ACAT2, displaying greater selectivity for ACAT2 than for ACAT1. The molecular mechanisms governing the inhibitory activities of the selected compounds were systematically elucidated using computational approaches. In addition, hotspot residues in ACAT2 that are crucial for ligand binding were successfully identified. In summary, we devised a multilayer screening scheme to expeditiously and efficiently identify compounds with enzyme inhibitory activity, offering novel scaffolds for subsequent drug design centred on ACAT2 targets.

The clinical relevance of the reversal of coronary atherosclerotic plaque

Atherosclerotic cardiovascular disease (ASCVD) remains a leading cause of death globally despite advances in preventive therapies. Understanding of the initiation and progression of atherosclerosis, the interplay between lipoproteins, endothelial dysfunction, inflammation, and immune responses is critical to treating this disease. The development of vulnerable coronary plaques prone to thrombosis, can lead to acute coronary syndromes, for these reasons, the potential plaque stabilization and regression through pharmacological interventions, particularly lipid-lowering agents like statins and PCSK9 inhibitors is crucial. The imaging techniques such as intravascular ultrasound (IVUS), near-infrared spectroscopy (NIRS), and optical coherence tomography (OCT) play a key role in assessing plaque composition and guiding interventional therapeutic strategies. Clinical evidence supports the efficacy of intensive lipid-lowering therapy in inducing plaque regression, with studies demonstrating reductions in plaque volume and improvements in plaque morphology assessed by IVUS, OCT and NIRS. While pharmacological interventions show promise in promoting plaque regression and stabilization, their impact on long-term cardiovascular events requires further investigation. Multimodality imaging and comprehensive outcome trials are proposed as essential tools for elucidating the relationship between plaque modification and clinical benefit in coronary atherosclerosis. The stabilization or regression of atherosclerotic plaque might serve as the phenomenon linking the reduction in LDL-C levels to the decrease in cardiovascular events. Overall, this review emphasizes the ongoing efforts to advance our understanding of ASCVD pathophysiology and optimize therapeutic approaches for improving patient outcomes.

Interplay of Age and Risk Factor Control Upon Coronary Atheroma Progression

BACKGROUND & AIM

The extent and composition of coronary plaque, and its progression differ with patients' age. The interplay of patient's age with respect to risk factor control, upon atheroma progression has not been evaluated. We tested the hypothesis that risk factor control modulates the association between age and coronary atheroma progression.

METHOD

We performed a posthoc pooled analysis of data from 10 prospective, randomised trials involving serial coronary intravascular ultrasonography (IVUS) (n=5,823). The percent atheroma volume (PAV) was calculated as the proportion of the entire vessel wall occupied by atherosclerotic plaque.

RESULTS

Mean overall age was 58±9 years (28% women). In a fully adjusted multivariable analysis (following adjustment of sex, body mass index, systolic blood pressure [SBP], smoking, high-density lipoprotein and low-density lipoprotein [LDL]-cholesterol, triglyceride levels, peripheral vascular disease, diabetes mellitus, trial, region, and baseline PAV), an increase in age by one standard deviation was linked with PAV progression (β-estimate 0.097; 95% confidence interval 0.048-0.15; p<0.001). In patients with good risk factor control (LDL-cholesterol <1.8 mmol/L and SBP <130 mmHg), increasing age remained associated with PAV progression (0.123; 0.014-0.23; p=0.027). Lower effect sizes for the association of age with PAV progression were observed for patients with partial control of LDL-cholesterol and SBP and were not significantly associated with PAV progression when both LDL-cholesterol and SBP were not controlled (0.099; 0.032-0.167; p=0.004 and 0.042; -0.056 to 0.14; p=0.40, respectively).

CONCLUSIONS

Patient age is directly associated with coronary atheroma progression independently of traditional cardiovascular risk factors. In the setting of poor risk factor control, the influence of age on coronary artery disease progression is attenuated.

Characterization of Stealth Liposome-Based Nanoparticles Encapsulating the ACAT1/SOAT1 Inhibitor F26: Efficacy and Toxicity Studies In Vitro and in Wild-Type Mice

Cholesterol homeostasis is pivotal for cellular function. Acyl-coenzyme A:cholesterol acyltransferase 1 (ACAT1), also abbreviated as SOAT1, is an enzyme responsible for catalyzing the storage of excess cholesterol to cholesteryl esters. ACAT1 is an emerging target to treat diverse diseases including atherosclerosis, cancer, and neurodegenerative diseases. F12511 is a high-affinity ACAT1 inhibitor. Previously, we developed a stealth liposome-based nanoparticle to encapsulate F12511 to enhance its delivery to the brain and showed its efficacy in treating a mouse model for Alzheimer's disease (AD). In this study, we introduce F26, a close derivative of F12511 metabolite in rats. F26 was encapsulated in the same DSPE-PEG2000/phosphatidylcholine (PC) liposome-based nanoparticle system. We employed various in vitro and in vivo methodologies to assess F26's efficacy and toxicity compared to F12511. The results demonstrate that F26 is more effective and durable than F12511 in inhibiting ACAT1, in both mouse embryonic fibroblasts (MEFs), and in multiple mouse tissues including the brain tissues, without exhibiting any overt systemic or neurotoxic effects. This study demonstrates the superior pharmacokinetic and safety profile of F26 in wild-type mice, and suggests its therapeutic potential against various neurodegenerative diseases including AD.

The Neurolipid Atlas: a lipidomics resource for neurodegenerative diseases uncovers cholesterol as a regulator of astrocyte reactivity impaired by ApoE4

Lipid changes in the brain have been implicated in many neurodegenerative diseases including Alzheimer's Disease (AD), Parkinson's disease and Amyotrophic Lateral Sclerosis. To facilitate comparative lipidomic research across brain-diseases we established a data commons named the Neurolipid Atlas, that we have pre-populated with novel human, mouse and isogenic induced pluripotent stem cell (iPSC)-derived lipidomics data for different brain diseases. We show that iPSC-derived neurons, microglia and astrocytes display distinct lipid profiles that recapitulate in vivo lipotypes. Leveraging multiple datasets, we show that the AD risk gene ApoE4 drives cholesterol ester (CE) accumulation in human astrocytes recapitulating CE accumulation measured in the human AD brain. Multi-omic interrogation of iPSC-derived astrocytes revealed that cholesterol plays a major role in astrocyte interferon-dependent pathways such as the immunoproteasome and major histocompatibility complex (MHC) class I antigen presentation. We show that through enhanced cholesterol esterification ApoE4 suppresses immune activation of astrocytes. Our novel data commons, available at neurolipidatlas.com, provides a user-friendly tool and knowledge base for a better understanding of lipid dyshomeostasis in neurodegenerative diseases.

Macrophages in cardiovascular diseases: molecular mechanisms and therapeutic targets

The immune response holds a pivotal role in cardiovascular disease development. As multifunctional cells of the innate immune system, macrophages play an essential role in initial inflammatory response that occurs following cardiovascular injury, thereby inducing subsequent damage while also facilitating recovery. Meanwhile, the diverse phenotypes and phenotypic alterations of macrophages strongly associate with distinct types and severity of cardiovascular diseases, including coronary heart disease, valvular disease, myocarditis, cardiomyopathy, heart failure, atherosclerosis and aneurysm, which underscores the importance of investigating macrophage regulatory mechanisms within the context of specific diseases. Besides, recent strides in single-cell sequencing technologies have revealed macrophage heterogeneity, cell-cell interactions, and downstream mechanisms of therapeutic targets at a higher resolution, which brings new perspectives into macrophage-mediated mechanisms and potential therapeutic targets in cardiovascular diseases. Remarkably, myocardial fibrosis, a prevalent characteristic in most cardiac diseases, remains a formidable clinical challenge, necessitating a profound investigation into the impact of macrophages on myocardial fibrosis within the context of cardiac diseases. In this review, we systematically summarize the diverse phenotypic and functional plasticity of macrophages in regulatory mechanisms of cardiovascular diseases and unprecedented insights introduced by single-cell sequencing technologies, with a focus on different causes and characteristics of diseases, especially the relationship between inflammation and fibrosis in cardiac diseases (myocardial infarction, pressure overload, myocarditis, dilated cardiomyopathy, diabetic cardiomyopathy and cardiac aging) and the relationship between inflammation and vascular injury in vascular diseases (atherosclerosis and aneurysm). Finally, we also highlight the preclinical/clinical macrophage targeting strategies and translational implications.

Lipotoxicity as a therapeutic target in obesity and diabetic cardiomyopathy

Unhealthy sources of fats, ultra-processed foods with added sugars, and a sedentary lifestyle make humans more susceptible to developing overweight and obesity. While lipids constitute an integral component of the organism, excessive and abnormal lipid accumulation that exceeds the storage capacity of lipid droplets disrupts the intracellular composition of fatty acids and results in the release of deleterious lipid species, thereby giving rise to a pathological state termed lipotoxicity. This condition induces endoplasmic reticulum stress, mitochondrial dysfunction, inflammatory responses, and cell death. Recent advances in omics technologies and analytical methodologies and clinical research have provided novel insights into the mechanisms of lipotoxicity, including gut dysbiosis, epigenetic and epitranscriptomic modifications, dysfunction of lipid droplets, post-translational modifications, and altered membrane lipid composition. In this review, we discuss the recent knowledge on the mechanisms underlying the development of lipotoxicity and lipotoxic cardiometabolic disease in obesity, with a particular focus on lipotoxic and diabetic cardiomyopathy.

The novel molecular mechanism of pulmonary fibrosis: insight into lipid metabolism from reanalysis of single-cell RNA-seq databases

Pulmonary fibrosis (PF) is a severe pulmonary disease with limited available therapeutic choices. Recent evidence increasingly points to abnormal lipid metabolism as a critical factor in PF pathogenesis. Our latest research identifies the dysregulation of low-density lipoprotein (LDL) is a new risk factor for PF, contributing to alveolar epithelial and endothelial cell damage, and fibroblast activation. In this study, we first integrative summarize the published literature about lipid metabolite changes found in PF, including phospholipids, glycolipids, steroids, fatty acids, triglycerides, and lipoproteins. We then reanalyze two single-cell RNA-sequencing (scRNA-seq) datasets of PF, and the corresponding lipid metabolomic genes responsible for these lipids' biosynthesis, catabolism, transport, and modification processes are uncovered. Intriguingly, we found that macrophage is the most active cell type in lipid metabolism, with almost all lipid metabolic genes being altered in macrophages of PF. In type 2 alveolar epithelial cells, lipid metabolic differentially expressed genes (DEGs) are primarily associated with the cytidine diphosphate diacylglycerol pathway, cholesterol metabolism, and triglyceride synthesis. Endothelial cells are partly responsible for sphingomyelin, phosphatidylcholine, and phosphatidylethanolamines reprogramming as their metabolic genes are dysregulated in PF. Fibroblasts may contribute to abnormal cholesterol, phosphatidylcholine, and phosphatidylethanolamine metabolism in PF. Therefore, the reprogrammed lipid profiles in PF may be attributed to the aberrant expression of lipid metabolic genes in different cell types. Taken together, these insights underscore the potential of targeting lipid metabolism in developing innovative therapeutic strategies, potentially leading to extended overall survival in individuals affected by PF.

A study on cholesterol-cholesteryl ester metabolic homeostasis and drug intervention in hyperlipidemic hamsters using UHPLC-MS/MS

Hyperlipidemia is a global metabolic disorder characterized by dysregulation of lipid metabolism. This dysregulation is closely associated with the altered homeostasis of cholesterol-cholesteryl ester (CE) metabolism in systemic circulation, and some organs. Additionally, the relationship between oxidized cholesteryl ester (oxCE) and the disease has also gained attention. Currently, there is a lack of comprehensive research on the alterations in cholesterol-CE metabolism in the context of hyperlipidemia, as well as the characteristics of lipid-lowering agents in regulating this metabolic state. Therefore, 40 oxCEs were identified in the hamster liver sample, and novel ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) methods were established for simultaneous analysis of cholesterol, 57 CEs, and 40 oxCEs in the serum, liver, adipose tissue, and intestine of hyperlipidemic hamsters. This study investigated the metabolic alterations between cholesterol-CE/oxCE in hyperlipidemic hamsters and those treated with lipid-lowering agents, including the Niemann-Pick-C1 like-1 protein (NPC1L1) inhibitor ezetimibe and the acyl coenzyme A: cholesterol acyltransferase (ACAT) inhibitor avasimibe. The study findings demonstrate metabolic disorders in cholesterol-CE/oxCE homeostasis in hyperlipidemic hamsters. Lipid-lowering agent therapy can improve the metabolic dysregulation caused by hyperlipidemia, with distinct characteristics: ezetimibe is more effective in reducing cholesterol, while avasimibe is more effective in reducing CEs/oxCEs. Eight potential biomarkers indicating the dysregulation of cholesterol-CE metabolism caused by hyperlipidemia and its improvement by lipid-lowering agents have been identified in the serum. This study offers new insights into the hyperlipidemia pathophysiology and the mechanisms of lipid-lowering agents from a novel perspective on cholesterol-CE/oxCE metabolic homeostasis.

Translational Relevance of Advanced Age and Atherosclerosis in Preclinical Trials of Biotherapies for Peripheral Artery Disease

Approximately 6% of adults worldwide suffer from peripheral artery disease (PAD), primarily caused by atherosclerosis of lower limb arteries. Despite optimal medical care and revascularization, many PAD patients remain symptomatic and progress to critical limb ischemia (CLI) and risk major amputation. Delivery of pro-angiogenic factors as proteins or DNA, stem, or progenitor cells confers vascular regeneration and functional recovery in animal models of CLI, but the effects are not well replicated in patients and no pro-angiogenic biopharmacological procedures are approved in the US, EU, or China. The reasons are unclear, but animal models that do not represent clinical PAD/CLI are implicated. Consequently, it is unclear whether the obstacles to clinical success lie in the toxic biochemical milieu of human CLI, or in procedures that were optimized on inappropriate models. The question is significant because the former case requires abandonment of current strategies, while the latter encourages continued optimization. These issues are discussed in the context of relevant preclinical and clinical data, and it is concluded that preclinical mouse models that include age and atherosclerosis as the only comorbidities that are consistently present and active in clinical trial patients are necessary to predict clinical success. Of the reviewed materials, no biopharmacological procedure that failed in clinical trials had been tested in animal models that included advanced age and atherosclerosis relevant to PAD/CLI.

Coronary atherosclerotic plaque phenotype and physiopathologic mechanisms: Is there an influence of sex? Insights from intracoronary imaging

Coronary artery disease (CAD) is the leading cause of disability and death in both women and men; considerable differences in clinical presentation, natural history and prognosis are reported between sexes. Different pathophysiological mechanisms play a major role, including sex-related and gender-related features or a combination of both. Reports from intracoronary imaging studies pointed towards morphological plaque features, which seemed to differ between men and women, albeit results reported so far were not conclusive. The purpose of this review is to shed light on differences in the pathophysiology underlying CAD in women vs men including the description of coronary plaque phenotype and mechanisms of plaque instability, as assessed by intracoronary imaging. We will also discuss potential clinical implications with the aim to move towards a sex and gender-based personalized approach in CAD patients.

Stealth Liposomes Encapsulating a Potent ACAT1/SOAT1 Inhibitor F12511: Pharmacokinetic, Biodistribution, and Toxicity Studies in Wild-Type Mice and Efficacy Studies in Triple Transgenic Alzheimer's Disease Mice

Cholesterol is essential for cellular function and is stored as cholesteryl esters (CEs). CEs biosynthesis is catalyzed by the enzymes acyl-CoA:cholesterol acyltransferase 1 and 2 (ACAT1 and ACAT2), with ACAT1 being the primary isoenzyme in most cells in humans. In Alzheimer's Disease, CEs accumulate in vulnerable brain regions. Therefore, ACATs may be promising targets for treating AD. F12511 is a high-affinity ACAT1 inhibitor that has passed phase 1 safety tests for antiatherosclerosis. Previously, we developed a nanoparticle system to encapsulate a large concentration of F12511 into a stealth liposome (DSPE-PEG2000 with phosphatidylcholine). Here, we injected the nanoparticle encapsulated F12511 (nanoparticle F) intravenously (IV) in wild-type mice and performed an HPLC/MS/MS analysis and ACAT enzyme activity measurement. The results demonstrated that F12511 was present within the mouse brain after a single IV but did not overaccumulate in the brain or other tissues after repeated IVs. A histological examination showed that F12511 did not cause overt neurological or systemic toxicity. We then showed that a 2-week IV delivery of nanoparticle F to aging 3xTg AD mice ameliorated amyloidopathy, reduced hyperphosphorylated tau and nonphosphorylated tau, and reduced neuroinflammation. This work lays the foundation for nanoparticle F to be used as a possible therapy for AD and other neurodegenerative diseases.

Lipid-laden foam cells in the pathology of atherosclerosis: shedding light on new therapeutic targets

INTRODUCTION

Lipid-laden foam cells within atherosclerotic plaques are key players in all phases of lesion development including its progression, necrotic core formation, fibrous cap thinning, and eventually plaque rupture. Manipulating foam cell biology is thus an attractive therapeutic strategy at early, middle, and even late stages of atherosclerosis. Traditional therapies have focused on prevention, especially lowering plasma lipid levels. Despite these interventions, atherosclerosis remains a major cause of cardiovascular disease, responsible for the largest numbers of death worldwide.

AREAS COVERED

Foam cells within atherosclerotic plaques are comprised of macrophages, vascular smooth muscle cells, and other cell types which are exposed to high concentrations of lipoproteins accumulating within the subendothelial intimal layer. Macrophage-derived foam cells are particularly well studied and have provided important insights into lipid metabolism and atherogenesis. The contributions of foam cell-based processes are discussed with an emphasis on areas of therapeutic potential and directions for drug development.

EXERT OPINION

As key players in atherosclerosis, foam cells are attractive targets for developing more specific, targeted therapies aimed at resolving atherosclerotic plaques. Recent advances in our understanding of lipid handling within these cells provide insights into how they might be manipulated and clinically translated to better treat atherosclerosis.

Targeting sterol-O-acyltransferase 1 to disrupt cholesterol metabolism for cancer therapy

Cholesterol esterification is often dysregulated in cancer. Sterol O-acyl-transferase 1 (SOAT1) plays an important role in maintaining cellular cholesterol homeostasis by catalyzing the formation of cholesterol esters from cholesterol and long-chain fatty acids in cells. Many studies have implicated that SOAT1 plays a vital role in cancer initiation and progression and is an attractive target for novel anticancer therapy. In this review, we provide an overview of the mechanism and regulation of SOAT1 in cancer and summarize the updates of anticancer therapy targeting SOAT1.

Effects of Lipid Lowering Therapies on Vulnerable Plaque Features: An Updated Narrative Review of the Literature

The clinical evidence on the efficacy of lipid lowering therapy in patients with coronary artery disease (CAD) is unequivocally established. However, the effects of these therapies on plaque composition and stability are less clear. The use of intracoronary imaging (ICI) technologies has emerged as a complement to conventional angiography to further characterize plaque morphology and detect high-risk plaque features related to cardiovascular events. Along with clinical outcomes studies, parallel imaging trials employing serial evaluations with intravascular ultrasound (IVUS) have shown that pharmacological treatment has the capacity to either slow disease progression or promote plaque regression, depending on the degree of lipid lowering achieved. Subsequently, the introduction of high-intensity lipid lowering therapy led to much lower levels of low-density lipoprotein cholesterol (LDL-C) levels than achieved in the past, resulting in greater clinical benefit. However, the degree of atheroma regression showed in concomitant imaging trials appeared more modest as compared to the magnitude of clinical benefit accrued from high-intensity statin therapy. Recently, new randomized trials have investigated the additional effects of achieving very low levels of LDL-C on high-risk plaque features-such as fibrous cap thickness and large lipid accumulation-beyond its size. This paper provides an overview of the currently available evidence of the effects of moderate to high-intensity lipid lowering therapy on high-risk plaque features as assessed by different ICI modalities, reviews data supporting the use of these trials, and analyse the future perspectives in this field.

Lipid droplet biogenesis and functions in health and disease

Ubiquitous yet unique, lipid droplets are intracellular organelles that are increasingly being recognized for their versatility beyond energy storage. Advances uncovering the intricacies of their biogenesis and the diversity of their physiological and pathological roles have yielded new insights into lipid droplet biology. Despite these insights, the mechanisms governing the biogenesis and functions of lipid droplets remain incompletely understood. Moreover, the causal relationship between the biogenesis and function of lipid droplets and human diseases is poorly resolved. Here, we provide an update on the current understanding of the biogenesis and functions of lipid droplets in health and disease, highlighting a key role for lipid droplet biogenesis in alleviating cellular stresses. We also discuss therapeutic strategies of targeting lipid droplet biogenesis, growth or degradation that could be applied in the future to common diseases, such as cancer, hepatic steatosis and viral infection.

Targeting Sterol O-Acyltransferase/Acyl-CoA:Cholesterol Acyltransferase (ACAT): A Perspective on Small-Molecule Inhibitors and Their Therapeutic Potential

Sterol O-acyltransferase (SOAT) is a membrane-bound enzyme that aids the esterification of cholesterol and fatty acids to cholesterol esters. SOAT has been studied extensively as a potential drug target, since its inhibition can serve as an alternative to statin therapy. Two SOAT isozymes that have discrete functions in the human body, namely, SOAT1 and SOAT2, have been characterized. Over three decades of research has focused on candidate SOAT1 inhibitors with unsatisfactory results in clinical trials. Recent research has focused on targeting SOAT2 selectively. In this perspective, we summarize the literature covering various SOAT inhibitory agents and discuss the design, structural requirements, and mode of action of SOAT inhibitors.

Association between ACAT1 rs1044925 and increased hypertension risk in Tongdao Dong

Hypertension is a multifactorial disease that partially caused by genetic factors, including variation in genes related to lipid metabolism. ACAT1 gene is implicated in lipid metabolism for its encoding product, the enzyme acetyl-CoA acetyltransferase 1, catalyzing the synthesis of cholesteryl ester from cholesterol and playing an important role in the metabolism of cholesterol. Until now, there's little study on the relationship between ACAT1 variants and hypertension. Here, we report a link between ACAT1 rs1044925 and hypertension in Tongdao Dong population. Polymerase chain reaction-restriction fragment length polymorphism was used to detect the genotypes of the ACAT1 SNP rs1044925 in a total of 637 subjects, including 406 hypertensive patients and 231 normotensive controls. The genotypic and allelic frequencies of rs1044925 were significantly different between the normotensive and hypertensive subjects (P = .001). AC/CC genotypes of rs1044925 were associated with an increased risk of hypertension (AC/CC vs AA: adjusted odds ratio = 1.723, 95% confidence interval = 1.160-2.559, P = .007). However, the AC/CC genotypes showed no relationship with serum lipid levels. The results suggest that the C carriers of ACAT1 rs1044925 might increase the risk of hypertension in Tongdao Dong population, and the underlying mechanism needs to be further studied.

Sterol O-Acyltransferase Inhibition Ameliorates High-Fat Diet-Induced Renal Fibrosis and Tertiary Lymphoid Tissue Maturation after Ischemic Reperfusion Injury

Metabolic syndrome is associated with the development of chronic kidney disease (CKD). We previously demonstrated that aged kidneys are prone to developing tertiary lymphoid tissues (TLTs) and sustain inflammation after injury, leading to CKD progression; however, the relationship between renal TLT and metabolic syndrome is unknown. In this study, we demonstrated that a high-fat diet (HFD) promoted renal TLT formation and inflammation via sterol O-acyltransferase (SOAT) 1-dependent mechanism. Mice fed a HFD prior to ischemic reperfusion injury (IRI) exhibited pronounced renal TLT formation and sustained inflammation compared to the controls. Untargeted lipidomics revealed the increased levels of cholesteryl esters (CEs) in aged kidneys with TLT formation after IRI, and, consistently, the Soat1 gene expression increased. Treatment with avasimibe, a SOAT inhibitor, attenuated TLT maturation and renal inflammation in HFD-fed mice subjected to IRI. Our findings suggest the importance of SOAT1-dependent CE accumulation in the pathophysiology of CKDs associated with TLT.

Noninvasive Plaque Imaging to Accelerate Coronary Artery Disease Drug Development

Coronary artery disease (CAD) remains the leading cause of adult mortality globally. Targeting known modifiable risk factors has had substantial benefit, but there remains a need for new approaches. Improvements in invasive and noninvasive imaging techniques have enabled an increasing recognition of distinct quantitative phenotypes of coronary atherosclerosis that are prognostically relevant. There are marked differences in plaque phenotype, from the high-risk, lipid-rich, thin-capped atheroma to the low-risk, quiescent, eccentric, nonobstructive calcified plaque. Such distinct phenotypes reflect different pathophysiologic pathways and are associated with different risks for acute ischemic events. Noninvasive coronary imaging techniques, such as computed tomography, positron emission tomography, and coronary magnetic resonance imaging, have major potential to accelerate cardiovascular drug development, which has been affected by the high costs and protracted timelines of cardiovascular outcome trials. This may be achieved through enrichment of high-risk phenotypes with higher event rates or as primary end points of drug efficacy, at least in phase 2 trials, in a manner historically performed through intravascular coronary imaging studies. Herein, we provide a comprehensive review of the current technology available and its application in clinical trials, including implications for sample size requirements, as well as potential limitations. In its effort to accelerate drug development, the US Food and Drug Administration has approved surrogate end points for 120 conditions, but not for CAD. There are robust data showing the beneficial effects of drugs, including statins, on CAD progression and plaque stabilization in a manner that correlates with established clinical end points of mortality and major adverse cardiovascular events. This, together with a clear mechanistic rationale for using imaging as a surrogate CAD end point, makes it timely for CAD imaging end points to be considered. We discuss the importance of global consensus on these imaging end points and protocols and partnership with regulatory bodies to build a more informed, sustainable staged pathway for novel therapies.

Use of cholesterol metabolism for anti-cancer strategies

Irregularities in cholesterol metabolism occur in a range of human cancers. Cholesterol precursors and derivatives support tumorigenesis and weaken immune responses. Intriguing preclinical and clinical findings demonstrate that cholesterol biosynthesis inhibition achieved by targeting major events and metabolites in cholesterol metabolism is an ideal anti-tumor strategy. Investigations addressing the effects of β-hydroxy β-methylglutaryl-CoA (HMG-CoA) reductase (HMGCR), 2,3-oxidosqualene cyclase (OSC), squalene synthase (SQS), liver X receptors (LXR), and cholesterol trafficking and esterification inhibition on cancer progression have shown encouraging results. Notably, manipulation of cholesterol metabolism strengthens the function of immune cells in the tumor microenvironment (TME). In this review, I discuss the role of cholesterol metabolism in cancer progression and the latest research related to cholesterol metabolism-based anti-cancer therapies and intend to bring this stylish biochemistry topic to the Sri Lankan research landscape.

Plasma FA composition in familial LCAT deficiency indicates SOAT2-derived cholesteryl ester formation in humans

Mutations in the LCAT gene cause familial LCAT deficiency (Online Mendelian Inheritance in Man ID: #245900), a very rare metabolic disorder. LCAT is the only enzyme able to esterify cholesterol in plasma, whereas sterol O-acyltransferases 1 and 2 are the enzymes esterifying cellular cholesterol in cells. Despite the complete lack of LCAT activity, patients with familial LCAT deficiency exhibit circulating cholesteryl esters (CEs) in apoB-containing lipoproteins. To analyze the origin of these CEs, we investigated 24 carriers of LCAT deficiency in this observational study. We found that CE plasma levels were significantly reduced and highly variable among carriers of two mutant LCAT alleles (22.5 [4.0-37.8] mg/dl) and slightly reduced in heterozygotes (218 [153-234] mg/dl). FA distribution in CE (CEFA) was evaluated in whole plasma and VLDL in a subgroup of the enrolled subjects. We found enrichment of C16:0, C18:0, and C18:1 species and a depletion in C18:2 and C20:4 species in the plasma of carriers of two mutant LCAT alleles. No changes were observed in heterozygotes. Furthermore, plasma triglyceride-FA distribution was remarkably similar between carriers of LCAT deficiency and controls. CEFA distribution in VLDL essentially recapitulated that of plasma, being mainly enriched in C16:0 and C18:1, while depleted in C18:2 and C20:4. Finally, after fat loading, chylomicrons of carriers of two mutant LCAT alleles showed CEs containing mainly saturated FAs. This study of CEFA composition in a large cohort of carriers of LCAT deficiency shows that in the absence of LCAT-derived CEs, CEs present in apoB-containing lipoproteins are derived from hepatic and intestinal sterol O-acyltransferase 2.

Facile method to incorporate high-affinity ACAT/SOAT1 inhibitor F12511 into stealth liposome-based nanoparticle and demonstration of its efficacy in blocking cholesteryl ester biosynthesis without overt toxicity in neuronal cell culture

BACKGROUND

Acyl-CoA:cholesterol acyltransferase (ACAT) inhibitors have been considered as potential therapeutic agents to treat several diseases, including Alzheimer's disease, atherosclerosis, and cancer. While many ACAT inhibitors are readily available, methods to encapsulate them as nanoparticles have not been reported.

NEW METHOD

We report a simple method to encapsulate ACAT inhibitors, using the potent hydrophobic ACAT inhibitor F12511 as an example. By mixing DSPE-PEG_2000, egg phosphatidylcholine (PC), and F12511 in ethanol, followed by drying, resuspension and sonication in buffer, we show that F12511 can be encapsulated as stealth liposomes at high concentration.

RESULTS

We successfully incorporated F12511 into nanoparticles and found that increasing PC in the nanoparticles markedly increased the amount of F12511 incorporated in stealth liposomes. The nanoparticles containing F12511 (Nanoparticle F) exhibit average size of approximately 200 nm and are stable at 4 ºC for at least 6 months. Nanoparticle F is very effective at inhibiting ACAT in human and mouse neuronal and microglial cell lines. Toxicity tests using mouse primary neuronal cells show that F12511 alone or Nanoparticle F added at concentrations from 2 to 10 µM for 24-, 48-, and 72-hours produces minimal, if any, toxicity.

COMPARISON WITH EXISTING METHOD(S)

Unlike existing methods, the current method is simple, cost effective, and can be expanded to produce tagged liposomes to increase specificity of delivery. This also offers opportunity to embrace water soluble agent(s) within the aqueous compartment of the nanoparticles for potential combinatorial therapy.

CONCLUSIONS

This method shows promise for delivery of hydrophobic ACAT inhibitors at high concentration in vivo.

ACAT-1-Regulated Cholesteryl Ester Accumulation Modulates Gemcitabine Resistance in Biliary Tract Cancer

BACKGROUND

Biliary tract cancer (BTC) has few choices of chemotherapy, including gemcitabine, therefore exploring the mechanisms of gemcitabine resistance is important. We focused on lipid metabolism because biliary tract epithelial cells are essential in cholesterol and bile acid metabolism and the messenger RNA (mRNA) microarray analysis showed high acyl coenzyme A: cholesterol acyltransferase 1 (ACAT-1) expression in BTC gemcitabine-resistant (GR) cell lines. We hypothesized that aberrant accumulation of cholesteryl ester (CE) regulated by ACAT-1 could modulate GR in BTC.

METHODS

CE accumulations were measured in human BTC cell lines, and the relationships between CE levels, ACAT-1 expressions, and gemcitabine sensitivity were analyzed. We performed a small-interfering RNA (siRNA)-mediated knockdown and biochemical inhibition of ACAT-1 in BTC cell lines and alterations of gemcitabine sensitivity were evaluated. To evaluate the clinical significance of ACAT-1 in regard to GR, immunohistochemistry was performed and ACAT-1 expressions were analyzed in resected BTC specimens.

RESULTS

CE levels were correlated with ACAT-1 expressions and GR in four human BTC cell lines. siRNA-mediated knockdown of ACAT-1 in two independent GR cell clones as well as ACAT-1 inhibitor treatment significantly increased gemcitabine sensitivity; knockdown of ACAT-1: 5.63- and 8.02-fold; ACAT-1 inhibitor: 8.75- and 9.13-fold, respectively. ACAT-1 expression in resected BTC specimens revealed that the disease-free survival of the ACAT-1 low-intensity group (median 2.3 years) had a significantly better outcome than that of the ACAT-1 high-intensity group (median 1.1 years) under gemcitabine treatment after surgery (*p < 0.05).

CONCLUSIONS

Our findings suggest that CE and ACAT-1 might be a novel therapeutic target for GR in BTC.

Coronary Atherosclerotic Plaque Regression: JACC State-of-the-Art Review

Over the last 3 decades there have been substantial improvements in treatments aimed at reducing cardiovascular (CV) events. As these treatments have been developed, there have been parallel improvements in coronary imaging modalities that can assess plaque volumes and composition, using both invasive and noninvasive techniques. Plaque progression can be seen to precede CV events, and therefore, many studies have longitudinally assessed changes in plaque characteristics in response to various treatments, aiming to demonstrate plaque regression and improvements in high-risk features, with the rationale being that this will reduce CV events. In the past, decisions surrounding treatments for atherosclerosis have been informed by population-based risk scores for initiation in primary prevention and low-density lipoprotein cholesterol levels for titration in secondary prevention. If outcome data linking plaque regression to reduced CV events emerge, it may become possible to directly image plaque treatment response to guide management decisions.

The Effect of Orlistat on Sterol Metabolism in Obese Patients

BACKGROUND

Orlistat, a reversible inhibitor of pancreatic and gastric lipase, is known to have anti-obesity and antioxidant properties. Cholesterol intermediates and metabolites have diverse and important functions in cardiovascular disease. Therefore, we aimed to evaluate the effect of orlistat on sterol metabolism in overweight and obese adults after weight loss during the intervention or weight loss at 12 weeks.

METHODS

A total of 51 (27 in the control group and 24 in the experimental group), patients with a BMI of 27 or greater were randomly assigned in a 1:1 ratio to receive either orlistat (120 mg) three times a day plus phentermine hydrochloride (37.5 mg) once daily or a placebo three times a day plus phentermine hydrochloride (37.5 mg) once daily. The primary study outcome was sterol metabolism.

RESULTS

The experimental group exhibited significantly decreased metabolic signatures of serum sterols, free cholesterol, sitosterol, 7α-hydroxycholesterol (7α-OHC), and 7β-OHC at 12 weeks. The experimental group also exhibited significantly decreased metabolic ratios of sitosterol and 7α-OHC to cholesterol at 12 weeks. Regarding changes in sterol signatures from baseline to 6-month follow-up, free cholesterol, plant sterols, and cholesterol precursors tended to decrease with weight loss during the intervention and increase again as the weight was regained in both groups.

CONCLUSION

Orlistat treatment improves oxysterol metabolism in overweight and obese adults. Our findings support that orlistat plays a crucial role in the process of endothelial dysfunction and atherosclerosis via oxysterol modulation.

Blocking cholesterol storage to treat Alzheimer's disease

Cholesterol serves as an essential lipid molecule in various membrane organelles of mammalian cells. The metabolites of cholesterol also play important functions. Acyl-coenzyme A: cholesterol acyltransferase 1 (ACAT1), also named as sterol O-acyltransferase 1, is a membrane-bound enzyme residing at the endoplasmic reticulum (ER). It converts cholesterol to cholesteryl esters (CEs) for storage, and is expressed in all cells. CEs cannot partition in membranes; they can only coalesce as cytosolic lipid droplets. Excess CEs are found in the vulnerable region of the brains of patients with late-onset Alzheimer's disease (AD), and in cell and mouse models for AD. Reducing CE contents by genetic inactivation of ACAT1, or by pharmacological inhibition of ACAT is shown to reduce amyloidopathy and other hallmarks for AD. To account for the various beneficial actions of the ACAT1 blockade (A1B), a working hypothesis is proposed here: the increase in CE contents observed in the AD brain is caused by damages of cholesterol-rich lipid rafts that are known to occur in neurons affected by AD. These damages cause cholesterol to release from lipid rafts and move to the ER where it will be converted to CEs by ACAT1. In addition, the increase in CE contents may also be caused by overloading with cholesterol-rich substances, or through activation of ACAT1 gene expression by various proinflammatory agents. Both scenarios may occur in microglia of the chronically inflamed brain. A1B ameliorates AD by diverting the cholesterol pool destined for CE biosynthesis such that it can be utilized more efficiently to repair membrane damage in various organelles, and to exert regulatory actions more effectively to defend against AD. To test the validity of the A1B hypothesis in cell culture and in vivo, the current status of various anti-ACAT1 agents that could be further developed is briefly discussed.

Formation and Cellular Impact of Cholesterol Crystals in Health and Disease

Cholesterol crystals (CCs) were first discovered in atherosclerotic plaque tissue in the early 1900 and have since been observed and implicated in many diseases and conditions, including myocardial infarction, abdominal aortic aneurism, kidney disease, ocular diseases, and even central nervous system anomalies. Despite the widespread involvement of CCs in many pathologies, the mechanisms involved in their formation and their role in various diseases are still not fully understood. Current knowledge concerning the formation of CCs, as well as the molecular pathways activated upon cellular exposure to CCs, will be explored in this review. As CC formation is tightly associated with lipid metabolism, the role of cellular lipid homeostasis in the formation of CCs is highlighted, including the role of lysosomes. In addition, cellular pathways and processes known to be affected by CCs are described. In particular, CC-induced activation of the inflammasome and production of reactive oxygen species, along with the role of CCs in complement-mediated inflammation is discussed. Moreover, the clinical manifestation of embolized CCs is described with a focus on renal and skin diseases associated with CC embolism. Lastly, potential therapeutic measures that target either the formation of CCs or their impact on different cell types and tissues are highlighted.

The Initial Human Atherosclerotic Lesion and Lipoprotein Modification-A Deep Connection

Atherosclerosis research typically focuses on the evolution of intermediate or advanced atherosclerotic lesions rather than on prelesional stages of atherogenesis. Yet these early events may provide decisive leads on the triggers of the pathologic process, before lesions become clinically overt. Thereby, it is mandatory to consider extracellular lipoprotein deposition at this stage as the prerequisite of foam cell formation leading to a remarkable accumulation of LDL (Low Density Lipoproteins). As progression of atherosclerosis displays the characteristic features of a chronic inflammatory process on the one hand and native LDL lacks inflammatory properties on the other hand, the lipoprotein must undergo biochemical modification to become atherogenic. During the last 25 years, evidence was accumulated in support of a different concept on atherogenesis proposing that modification of native LDL occurs through the action of ubiquitous hydrolytic enzymes (enzymatically modified LDL or eLDL) rather than oxidation and contending that the physiological events leading to macrophage uptake and reverse transport of eLDL first occur without inflammation (initiation with reversion). Preventing or reversing initial atherosclerotic lesions would avoid the later stages and therefore prevent clinical manifestations. This concept is in accordance with the response to retention hypothesis directly supporting the strategy of lowering plasma levels of atherogenic lipoproteins as the most successful therapy for atherosclerosis and its sequelae. Apart from but unquestionable closely related to this concept, there are several other hypotheses on atherosclerotic lesion initiation favoring an initiating role of the immune system ('vascular-associated lymphoid tissue' (VALT)), defining foam cell formation as a variant of lysosomal storage disease, relating to the concept of the inflammasome with crystalline cholesterol and/or mitochondrial DAMPs (damage-associated molecular patterns) being mandatory in driving arterial inflammation and, last but not least, pointing to miRNAs (micro RNAs) as pivotal players. However, direct anti-inflammatory therapies may prove successful as adjuvant components but will likely never be used in the absence of strategies to lower plasma levels of atherogenic lipoproteins, the key point of the perception that atherosclerosis is not simply an inevitable result of senescence. In particular, given the importance of chemical modifications for lipoprotein atherogenicity, regulation of the enzymes involved might be a tempting target for pharmacological research.

Acyl-Coenzyme A: Cholesterol Acyltransferase (ACAT) in Cholesterol Metabolism: From Its Discovery to Clinical Trials and the Genomics Era

The purification and cloning of the acyl-coenzyme A: cholesterol acyltransferase (ACAT) enzymes and the sterol O-acyltransferase (SOAT) genes has opened new areas of interest in cholesterol metabolism given their profound effects on foam cell biology and intestinal lipid absorption. The generation of mouse models deficient in Soat1 or Soat2 confirmed the importance of their gene products on cholesterol esterification and lipoprotein physiology. Although these studies supported clinical trials which used non-selective ACAT inhibitors, these trials did not report benefits, and one showed an increased risk. Early genetic studies have implicated common variants in both genes with human traits, including lipoprotein levels, coronary artery disease, and Alzheimer’s disease; however, modern genome-wide association studies have not replicated these associations. In contrast, the common SOAT1 variants are most reproducibly associated with testosterone levels.

High expression of Sterol-O-Acyl transferase 1 (SOAT1), an enzyme involved in cholesterol metabolism, is associated with earlier biochemical recurrence in high risk prostate cancer

Background

Prostate cancer (PCa) is the most frequent cancer in men. The prognosis of PCa is heterogeneous with many clinically indolent tumors and rare highly aggressive cases. Reliable tissue markers of prognosis are lacking. Active cholesteryl ester synthesis has been associated with prostate cancer aggressiveness. Sterol-O-Acyl transferases (SOAT) 1 and 2 catalyze cholesterol esterification in humans.

Objective

To investigate the value of SOAT1 and SOAT2 tissue expression as prognostic markers in high risk PCa.

Patients and methods

Formalin-fixed paraffin-embedded tissue samples from 305 high risk PCa cases treated with radical prostatectomy were analyzed for SOAT1 and SOAT2 protein expression by semi-quantitative immunohistochemistry. The Kaplan–Meier method and Cox proportional hazards modeling were used to compare outcome.

Main outcome measure

Biochemical recurrence (BCR) free survival.

Results

SOAT1 expression was high in 73 (25%) and low in 219 (75%; not evaluable: 13) tumors. SOAT2 was highly expressed in 40 (14%) and at low levels in 249 (86%) samples (not evaluable: 16). By Kaplan–Meier analysis, we found significantly shorter median BCR free survival of 93 months (95% confidence interval 23.6–123.1) in patients with high SOAT1 vs. 134 months (112.6–220.2, Log-rank p < 0.001) with low SOAT1. SOAT2 expression was not significantly associated with BCR. After adjustment for age, preoperative PSA, tumor stage, Gleason score, resection status, lymph node involvement and year of surgery, high SOAT1 but not SOAT2 expression was associated with shorter BCR free survival with a hazard ratio of 2.40 (95% CI 1.57–3.68, p < 0.001). Time to clinical recurrence and overall survival were not significantly associated with SOAT1 and SOAT2 expression

Conclusions

SOAT1 expression is strongly associated with BCR free survival alone and after multivariable adjustment in high risk PCa. SOAT1 may serve as a histologic marker of prognosis and holds promise as a future treatment target.

Targeting the Cholesterol Paradigm in the Risk Reduction for Atherosclerotic Cardiovascular Disease: Does the Mechanism of Action of Pharmacotherapy Matter for Clinical Outcomes?

Hypercholesterolemia is a well-established risk factor for atherosclerotic cardiovascular disease (ASCVD). Low-density lipoprotein cholesterol (LDL-C) has been labeled as "bad" cholesterol and high-density lipoprotein cholesterol (HDL-C) as "good" cholesterol. The prevailing hypothesis is that lowering blood cholesterol levels, especially LDL-C, reduces vascular deposition and retention of cholesterol or apolipoprotein B (apoB)-containing lipoproteins which are atherogenic. We review herein the clinical trial data on different pharmacological approaches to lowering blood cholesterol and propose that the mechanism of action of cholesterol lowering, as well as the amplitude of cholesterol reduction, are critically important in leading to improved clinical outcomes in ASCVD. The effects of bile acid sequestrants, fibrates, niacin, cholesteryl ester transfer protein (CETP) inhibitors, apolipoprotein A-I and HDL mimetics, apoB regulators, acyl coenzyme A: cholesterol acyltransferase (ACAT) inhibitors, cholesterol absorption inhibitors, statins, and proprotein convertase subtilisin kexin 9 (PCSK9) inhibitors, among other strategies are reviewed. Clinical evidence supports that different classes of cholesterol lowering or lipoprotein regulating approaches yielded variable effects on ASCVD outcomes, especially in cardiovascular and all-cause mortality. Statins are the most widely used cholesterol lowering agents and have the best proven cardiovascular event and survival benefits. Manipulating cholesterol levels by specific targeting of apoproteins or lipoproteins has not yielded clinical benefit. Understanding why lowering LDL-C by different approaches varies in clinical outcomes of ASCVD, especially in survival benefit, may shed further light on our evolving understanding of how cholesterol and its carrier lipoproteins are involved in ASCVD and aid in developing effective pharmacological strategies to improve the clinical outcomes of ASCVD.

Serial coronary CT angiography-derived fractional flow reserve and plaque progression can predict long-term outcomes of coronary artery disease

OBJECTIVE

To investigate the utility of coronary CT angiography-derived fractional flow reserve (FFR_CT) and plaque progression in patients undergoing serial coronary CT angiography for predicting major adverse cardiovascular events (MACE).

METHODS

This retrospective study evaluated patients suspected or known coronary artery disease who underwent serial coronary CT angiography examinations between January 2006 and December 2017 and followed up until June 2019. The primary endpoint was MACE, defined as acute coronary syndrome, rehospitalization due to progressive angina, percutaneous coronary intervention, or cardiac death. FFR_CT and plaque parameters were analyzed on a per-vessel and per-patient basis. Univariable and multivariable COX regression analysis determined predictors of MACE. The prognostic value of FFR_CT and plaque progression were assessed in nested models.

RESULTS

Two hundred eighty-four patients (median age, 61 years (interquartile range, 54-70); 202 males) were evaluated. MACE was observed in 45 patients (15.8%, 45/284). By Cox multivariable regression modeling, vessel-specific FFR_CT ≤ 0.80 was associated with a 2.4-fold increased risk of MACE (HR (95% CI): 2.4 (1.3-4.4); p = 0.005) and plaque progression was associated with a 9-fold increased risk of MACE (HR (95% CI): 9 (3.5-23); p < 0.001) after adjusting for clinical and imaging risk factors. FFR_CT and plaque progression improved the prediction of events over coronary artery calcium (CAC) score and high-risk plaques (HRP) in the receiver operating characteristics analysis (area under the curve: 0.70 to 0.86; p = 0.002).

CONCLUSIONS

Fractional flow reserve and plaque progression assessed by serial coronary CT angiography predicted the risk of future MACE.

KEY POINTS

• Vessel-specific CT angiography-derived fractional flow reserve (FFR_CT) ≤ 0.80 and plaque progression improved the prediction of events over current risk factors. • Major adverse cardiovascular events (MACE) significantly increased with the presence of plaque progression at follow-up stratified by the FFR_CT change group.

Novel insights: Dynamic foam cells derived from the macrophage in atherosclerosis

Atherosclerosis can be regarded as a chronic disease derived from the interaction between disordered lipoproteins and an unsuitable immune response. The evolution of foam cells is not only a significant pathological change in the early stage of atherosclerosis but also a key stage in the occurrence and development of atherosclerosis. The formation of foam cells is mainly caused by the imbalance among lipids uptake, lipids treatment, and reverse cholesterol transport. Although a large number of studies have summarized the source of foam cells and the mechanism of foam cells formation, we propose a new idea about foam cells in atherosclerosis. Rather than an isolated microenvironment, the macrophage multiple lipid uptake pathways, lipid internalization, lysosome, mitochondria, endoplasmic reticulum, neutral cholesterol ester hydrolase (NCEH), acyl-coenzyme A-cholesterol acyltransferase (ACAT), and reverse cholesterol transport are mutually influential, and form a dynamic process under multi-factor regulation. The macrophage takes on different uptake lipid statuses depending on multiple uptake pathways and intracellular lipids, lipid metabolites versus pro-inflammatory factors. Except for NCEH and ACAT, the lipid internalization of macrophages also depends on multicellular organelles including the lysosome, mitochondria, and endoplasmic reticulum, which are associated with each other. A dynamic balance between esterification and hydrolysis of cholesterol for macrophages is essential for physiology and pathology. Therefore, we propose that the foam cell in the process of atherosclerosis may be dynamic under multi-factor regulation, and collate this study to provide a holistic and dynamic idea of the foam cell.

Soat1 mediates the mouse strain effects on cholesterol loading-induced endoplasmic reticulum stress and CHOP expression in macrophages

We previously demonstrated that AKR vs. DBA/2 mouse bone marrow derived macrophages have higher levels of free cholesterol and lower levels of esterified cholesterol after cholesterol loading, and that AKR, but not DBA/2, macrophages induced C/EBP homologous protein (CHOP) expression after cholesterol loading. We earlier determined that the free and esterified cholesterol level effect is due to a truncation in the sterol O-acyltransferase 1 (Soat1) gene, encoding acetyl-coenzyme A acetyltransferase 1 (ACAT1). Here we examined the mechanism for the differential induction of CHOP by cholesterol loading. CHOP was induced in both strains after incubation with tunicamycin, indicating both strains have competent endoplasmic reticulum stress pathways. CHOP was induced when DBA/2 macrophages were cholesterol loaded in the presence of an ACAT inhibitor, indicating that the difference in free cholesterol levels were responsible for this strain effect. This finding was confirmed in macrophages derived from DBA/2 embryonic stem cells. Cholesterol loading of Soat1 gene edited cells, mimicking the AKR allele, led to increased free cholesterol levels and restored CHOP induction. The upstream pathway of free cholesterol induced endoplasmic reticulum stress was investigated; and, RNA-dependent protein kinase-like endoplasmic reticulum kinase (PERK) and inositol-requiring enzyme 1 α protein kinase (IRE1α) pathways were required for maximal CHOP expression.

Short-Term Acyl-CoA:Cholesterol Acyltransferase Inhibition, Combined with Apoprotein A1 Overexpression, Promotes Atherosclerosis Inflammation Resolution in Mice

Acyl-CoA:cholesterol acyltransferase (ACAT) mediates cellular cholesterol esterification. In atherosclerotic plaque macrophages, ACAT promotes cholesteryl ester accumulation, resulting in foam cell formation and atherosclerosis progression. Its complete inactivation in mice, however, showed toxic effects because of an excess of free cholesterol (FC) in macrophages, which can cause endoplasmic reticulum stress, cholesterol crystal formation, and inflammasome activation. Our previous studies showed that long-term partial ACAT inhibition, achieved by dietary supplementation with Fujirebio F1394, delays atherosclerosis progression in apoprotein E-deficient (Apoe ^-/-) mice by reducing plaque foam cell formation without inflammatory or toxic effects. Here, we determined whether short-term partial inhibition of ACAT, in combination with an enhanced systemic FC acceptor capacity, has synergistic benefits. Thus, we crossbred Apoe ^-/- with human apoprotein A1-transgenic (APOA1 ^tg/tg) mice, which have elevated cholesterol-effluxing high-density lipoprotein particles, and subjected Apoe ^-/- and APOA1 ^tg/tg/Apoe ^-/- mice to an atherogenic diet to develop advanced plaques. Then mice were either euthanized (baseline) or fed purified standard diet with or without F1394 for 4 more weeks. Plaques of APOA1 ^tg/tg/Apoe ^-/- mice fed F1394 showed a 60% reduction of macrophages accompanied by multiple other benefits, such as reduced inflammation and favorable changes in extracellular composition, in comparison with Apoe ^-/- baseline mice. In addition, there was no accumulation of cholesterol crystals or signs of toxicity. Overall, these results show that short-term partial ACAT inhibition, coupled to increased cholesterol efflux capacity, favorably remodels atherosclerosis lesions, supporting the potential of these combined therapies in the treatment of advanced atherosclerosis. SIGNIFICANCE STATEMENT: Short-term pharmacological inhibition of acyl-CoA:cholesterol acyltransferase-mediated cholesterol esterification, in combination with increased free cholesterol efflux acceptors, has positive effects in mice by 1) reducing the inflammatory state of the plaque macrophages and 2) favoring compositional changes associated with plaque stabilization. These effects occur without toxicity, showing the potential of these combined therapies in the treatment of advanced atherosclerosis.

Progression of coronary atherosclerosis in patients without standard modifiable risk factors

Background and aims

The outcome of patients with clinical coronary artery disease despite traditional risk factors is poorly understood.

Methods

Clinical characteristics and plaque burden on serial intravascular ultrasonography were compared in patients without (n ​= ​165) and with (n ​= ​492) standard modifiable risk factors after matching on age, sex and use of statins from a database of 5823 patients participating in clinical trials of anti-atherosclerotic therapies.

Results

Patients without standard modifiable risk factors had lower baseline systolic blood pressure (118 ​± ​12 vs. 129 ​± ​17 ​mmHg, p ​< ​0.001), low-density lipoprotein cholesterol (87 ​± ​21 vs. 104 ​± ​34 ​mg/dl, p ​< ​0.001), triglycerides [106 vs. 136 ​mg/dl, p ​< ​0.001)] and C-reactive protein [1.5 vs. 2.1 ​mg/l, p ​= ​0.001]. At baseline, patients without modifiable risk factors had a lower percent atheroma volume (35.7 ​± ​8.6 vs. 38 ​± ​8.8%, p ​= ​0.004) and total atheroma volume (174.7 ​± ​80 vs. 190.9 ​± ​84 ​mm³, p ​= ​0.03) and less images with calcification (22.2 vs. 26.5%, p ​= ​0.025). The use of aspirin and statin prior to and during the trials was similar. The use of ACE inhibitors and beta blockers was lower in the no risk factor group prior to and during the trials. The change in percent atheroma volume (−0.2 ​± ​2.8 vs. −0.1 ​± ​3.6%, p ​= ​0.71), total atheroma volume (−5.5 ​± ​23.4 vs. −3.8 ​± ​22.7 ​mm³, p ​= ​0.42), and the percentage of patients demonstrating any degree of progression (50.9% vs 45.1%, p ​= ​0.20) were similar in those without and with standard modifiable risk factors, respectively.

Conclusion

Patients who develop clinical coronary atherosclerosis without standard modifiable risk factors have similar rates of plaque progression to those with traditional risk factors.

•

Outcome of patients with CAD despite no traditional risk factors is poorly understood.

•

Serial intravascular ultrasound studies provide an opportunity to examine this.

•

Patients without standard risk factors had lower plaque burden and calcification.

•

Use of aspirin and statin was similar in patients with and without standard risk factors.

•

Plaque progression was similar in those without and with standard risk factors.

Association of Serum Lipoprotein (a) Levels and Coronary Atheroma Volume by Intravascular Ultrasound

Background

Lp(a) (lipoprotein (a)) is a risk factor for cardiovascular events, but the mechanism of increased risk is uncertain. This study evaluated the relationship between Lp(a) and coronary atheroma volume by intravascular ultrasound.

Methods and Results

This was a post hoc analysis of 6 randomized trials of coronary atheroma by intravascular ultrasound. The population was stratified into high (≥60 mg/dL) and low (<60 mg/dL) baseline serum Lp(a). The primary outcome was baseline coronary percent atheroma volume. A mixed model adjusted for baseline low density lipoprotein, ApoB (apoliporotein B100), non‐high density lipoprotein, sex, age, race, history of myocardial infarction, statin use, and intravascular ultrasound study was used to provide estimates of baseline plaque burden. Of 3943 patients, 17.3% (683) had Lp(a) ≥ 60 mg/dL and 82.7% (3260) had Lp(a) < 60 mg/dL. At baseline, uncorrected low density lipoprotein level (107.7 ± 32.0 versus 99.1 ± 31.5) and statin therapy (99.0% versus 97.0%) were higher in patients with high Lp(a) levels, but low density lipoprotein corrected for Lp(a) was lower (80.6 ± 32.0 versus 94.0 ± 31.4) in patients with high Lp(a) levels. Percent atheroma volume was significantly higher in the high Lp(a) group in unadjusted (38.2% [32.8, 43.6] versus 37.1% [31.4, 43.1], P=0.01) and risk‐adjusted analyses (38.7%±0.5 versus 37.5%±0.5, P<0.001). There was a significant association of increasing risk‐adjusted percent atheroma volume across quintiles of Lp(a) (Lp(a) quintiles 1‐5; 37.3 ± 0.5%, 37.2 ± 0.5%, 37.3 ± 0.5%, 38.0 ± 0.5%, 38.5 ± 0.5%, P=0.002).

Conclusions

Elevated Lp(a) is independently associated with increased percent atheroma volume. Further work is needed to clarify the relationship of Lp(a)‐lowering treatment with cardiovascular outcomes.

Intra-coronary Imaging for the Evaluation of Plaque Modifications Induced by Drug Therapies for Secondary Prevention

PURPOSE OF REVIEW

Patients diagnosed with coronary artery disease are at a high risk of subsequent cardiovascular events; therefore, secondary prevention in the form of therapeutic lifestyle changes, and drug therapies is vital. This article aims to review potential application of intra-coronary imaging for the evaluation of plaque modifications, induced by medications for secondary prevention for CAD.

RECENT FINDINGS

Intra-coronary imaging provides detailed information on the atherosclerotic plaque which is the primary pathological substrate for the recurrent ischemic cardiovascular events. These modalities can detect features associated with high risk and allow serial in vivo imaging of lesions. Therefore, intravascular imaging tools have been used in landmark studies and played a role in improving our understanding of the disease processes. Changes in size and plaque composition over time can be evaluated by these tools and may help understanding the impact of a treatment. Moreover, surrogate imaging end points can be used when testing new drugs for secondary prevention.

ACAT1 as a Therapeutic Target and its Genetic Relationship with Alzheimer's Disease

BACKGROUND

Alzheimer´s disease (AD) is a chronic and progressive disease which impacts caregivers, families and societies physically, psychologically and economically. Currently available drugs can only improve cognitive symptoms, have no impact on progression and are not curative, so identifying and studying new drug targets is important. There are evidences which indicate disturbances in cholesterol homeostasis can be related with AD pathology, especially the compartmentation of intracellular cholesterol and cytoplasmic cholesterol esters formed by acyl-CoA: cholesterol acyltransferase 1 (ACAT1) can be implicated in the regulation of amyloid-beta (Aβ) peptide, involved in AD. Blocking ACAT1 activity, beneficial effects are obtained, so it has been suggested that ACAT1 can be a potential new therapeutic target. The present review discusses the role of cholesterol homeostasis in AD pathology, especially with ACAT inhibitors, and how they have been raised as a therapeutic approach. In addition, the genetic relationship of ACAT and AD is discussed.

CONCLUSION

Although there are several lines of evidence from cell-based and animal studies that suggest that ACAT inhibition is an effective way of reducing cerebral Aβ, there is still an information gap in terms of mechanisms and concerns to cover before passing to the next level. Additionally, an area of interest that may be useful in understanding AD to subsequently propose new therapeutic approaches is pharmacogenetics; however, there is still a lot of missing information in this area.

Acidic extracellular pH promotes accumulation of free cholesterol in human monocyte-derived macrophages via inhibition of ACAT1 activity

BACKGROUND AND AIMS

In focal areas of advanced human atherosclerotic lesions, the intimal fluid is acidic. An acidic medium impairs the ABCA1-mediated cholesterol efflux from macrophages, so tending to increase their content of free cholesterol, which is then available for esterification by the macrophage enzyme ACAT1. Here we investigated whether low extracellular pH would affect the activity of ACAT1.

METHODS

- Human monocyte-derived macrophages were first incubated with acetyl-LDL at neutral and acidic conditions (pH 7.5, 6.5, and 5.5) to generate foam cells, and then the foam cells were incubated with [³H]oleate-BSA complexes, and the formation of [³H]oleate-labeled cholesteryl esters was measured. ACAT1 activity was also measured in cell-free macrophage extracts.

RESULTS

- In acidic media, ACAT1-dependent cholesteryl [³H]oleate generation became compromised in the developing foam cells and their content of free cholesterol increased. In line with this finding, ACAT1 activity in the soluble cell-free fraction derived from macrophage foam cells peaked at pH 7, and gradually decreased under acidic pH with a rapid drop below pH 6.5. Incubation of macrophages under progressively more acidic conditions (until pH 5.5) lowered the cytosolic pH of macrophages (down to pH 6.0). Such intracellular acidification did not affect macrophage gene expression of ACAT1 or the neutral CEH.

CONCLUSIONS

Exposure of human macrophage foam cells to acidic conditions lowers their intracellular pH with simultaneous decrease in ACAT1 activity. This reduces cholesterol esterification and thus leads to accumulation of potentially toxic levels of free cholesterol, a contributing factor to macrophage foam cell death.

C. elegans ACAT regulates lipolysis and its related lifespan in fasting through modulation of the genes in lipolysis and insulin/IGF-1 signaling

Overly active acyl-coenzyme A: cholesterol acyltransferases (ACATs) are known to contribute to the development of atherosclerosis, cancer cell proliferation and de novo lipogenesis. However, the role of ACAT in systemic lipid metabolism and its consequence of aging is unknown. Using avasimibe, a clinically proven ACAT inhibitor, and mboa-1 mutant strain, a homologous to mammalian ACAT, herein, we found that Ava treatment and mboa-1 mutant exhibited a decreased fat accumulation during feeding and increased lipolysis with extended lifespan of C. elegans during fasting. Our study highlights the essential role of ACAT inhibitor and mboa-1 in fat mobilization and the survival of C. elegans in fasting through the modulation of the genes involved in lipolysis and insulin/IGF-1 signaling.

Hyperlipidaemia and IFNgamma/TNFalpha Synergism are associated with cholesterol crystal formation in Endothelial cells partly through modulation of Lysosomal pH and Cholesterol homeostasis

BACKGROUND

Inflammation plays an important role in the development of cardiovascular disease (CVD). Patients with chronic inflammation diseases have high levels of inflammation and early fatal myocardial infarction due to early, unstable coronary plaques. Cholesterol crystals (CC) play a key role in atherogenesis. However, the underlying mechanisms of endothelial cell (EC)-derived CC formation are not well understood in chronic inflammation.

METHODS

We utilized a combination of a mouse psoriasis model (K14-Rac1V12 mouse model) and human psoriasis patients to study the effect of inflammatory cytokines on CC formation in ECs. Lysosomal pH, alterations in lipid load and inflammatory proteins were evaluated as potential mechanisms linking inflammatory cytokines to CC formation. Coronary CT angiography was performed (n = 224) to characterize potential IFNγ and TNFα synergism on vascular diseases in vivo.

FINDINGS

We detected CC presence in the aorta of K14-Rac1V12 mice on chow diet. IFNγ and TNFα were found to synergistically increase LDL-induced CC formation by almost 2-fold. There was an increase in lysosomal pH accompanied by a 28% loss in pH-dependent lysosomal signal and altered vATPaseV1E1 expression patterns. In parallel, we found that LDL+IFNγ/TNFα treatments increased free cholesterol content within EC and led to a decrease in SOAT-1 expression, an enzyme critically involved cholesterol homeostasis. Finally, the product of IFNγ and TNFα positively associated with early non-calcified coronary burden in patients with psoriasis (n = 224; β = 0.28, p < 0.001).

INTERPRETATION

Our results provide evidence that IFNγ and TNFα accelerate CC formation in endothelial cells in part by altering lysosomal pH and free cholesterol load. These changes promote early atherogenesis and contribute to understanding the burden of CVD in psoriasis.

FUNDING

Funding was provided by the Intramural Research Program at NIH (NNM) and the National Psoriasis Foundation (NNM and YB).

Oral Calcium Supplements Associate With Serial Coronary Calcification: Insights From Intravascular Ultrasound

OBJECTIVES

This study sought to evaluate and assess the extent of serial coronary artery calcification in response to oral calcium supplementation.

BACKGROUND

Oral calcium supplements are frequently used despite their cardiovascular safety remaining controversial. Their effects on serial coronary calcification are not well established.

METHODS

In a post hoc patient-level analysis of 9 prospective randomized trials using serial coronary intravascular ultrasound, changes in serial percentage of atheroma volume (PAV) and calcium indices (CaI) were compared in matched segments of patients coronary artery disease who were receiving concomitant calcium supplements (n = 447) and in those who did not receive supplements (n = 4,700) during an 18- to 24-month trial period.

RESULTS

Patients (mean age 58 ± 9 years; 73% were men; 43% received concomitant high-intensity statins) demonstrated overall annualized changes in PAV and CaI with a mean of -0.02 ± 1.9% (p = 0.44) and a median of 0.02 (interquartile range: 0.00 to 0.06) (p < 0.001) from baseline, respectively. Following propensity-weighted mixed modeling adjusting for treatment and a range of demographic, clinical, ultrasonic, and laboratory parameters (including but not limited to sex, race, baseline, and annualized change in PAV, baseline CaI, concomitant high-intensity statins, diabetes mellitus, renal function), there were no significant between-group differences in annualized changes in PAV (least-squares mean: 0.09; 95% confidence interval [CI]: -0.20 to 0.37 vs. 0.01; 95% CI: -0.27 to 0.29; p = 0.092) according to calcium supplement intake. Per a multivariable logistic regression model accounting for the range of covariates described, calcium supplementation independently associated with an increase in annualized CaI (odds ratio: 1.15; 95% CI: 1.05 to 1.26; p = 0.004).

CONCLUSIONS

Oral calcium supplementation may increase calcium deposition in the coronary vasculature independent of changes in atheroma volume. The impact of these changes on plaque stability and cardiovascular outcomes requires further investigation.

Visit-to-Visit Blood Pressure Variability, Coronary Atheroma Progression, and Clinical Outcomes

Importance

Visit-to-visit blood pressure variability (BPV) is associated with cardiovascular events, but mechanisms and therapeutic implications underlying this association are not well understood.

Objective

To examine the association of intraindividual BPV, coronary atheroma progression, and clinical outcomes using serial intravascular ultrasonography.

Design, Setting, and Participants

Post hoc patient-level analysis of 7 randomized clinical trials conducted from 2004 to 2016 involving 3912 patients in multicenter, international, clinic-based primary and tertiary care centers. Adult patients with coronary artery disease who underwent serial intravascular ultrasonography in the setting of a range of medical therapies were included. Data were analyzed between November 2017 and March 2019.

Exposures

Visit-to-visit BPV measured using intraindividual standard deviation over 3, 6, 12, 18, and 24 months.

Main Outcomes and Measures

Percent atheroma volume (PAV) progression and major adverse cardiovascular events (defined as death, myocardial infarction, stroke, urgent revascularization for acute coronary syndrome, and hospitalization for unstable angina).

Results

Of 3912 patients, the mean (SD) age was 58 (9) years, 1093 (28%) were women, and 3633 (93%) were white . Continuous change in PAV was significantly associated with systolic BPV (β, .049; 95% CI, 0.021-0.078; P = .001), diastolic BPV (β, .031; 95% CI, 0.002-0.059; P = .03), and pulse pressure variability (β, .036; 95% CI, 0.006-0.067; P = .02), without a signal for differential effect greater than or less than a mean BP of 140/90 mm Hg. The PAV progression as a binary outcome was significantly associated with systolic BPV (odds ratio, 1.09; 95% CI, 1.01-1.17; P = .02) but not diastolic BPV (odds ratio, 1.04; 95% CI, 0.97-1.11; P = .30) or pulse pressure variability (odds ratio, 1.03; 95% CI, 0.96-1.10; P = .47). Survival curves revealed a significant stepwise association between cumulative major adverse cardiovascular events and increasing quartiles of systolic BPV (Kaplan-Meier estimates for quartiles 1-4: 6.1% vs 8.5% vs 10.1% vs 12.0%, respectively; log-rank P <.001). These distinct stepwise associations were not seen with diastolic BPV or pulse pressure variability.

Conclusions and Relevance

Greater BPV, particularly systolic BPV, is significantly associated with coronary atheroma progression and adverse clinical outcomes. These data suggest maintaining stable blood pressure levels may be important to further improve outcomes in patients with coronary disease.

Structure of nevanimibe-bound tetrameric human ACAT1

Cholesterol is an essential component of mammalian cell membranes, constituting up to 50% of plasma membrane lipids. By contrast, it accounts for only 5% of lipids in the endoplasmic reticulum (ER)¹. The ER enzyme sterol O-acyltransferase 1 (also named acyl-coenzyme A:cholesterol acyltransferase, ACAT1) transfers a long-chain fatty acid to cholesterol to form cholesteryl esters that coalesce into cytosolic lipid droplets. Under conditions of cholesterol overload, ACAT1 maintains the low cholesterol concentration of the ER and thereby has an essential role in cholesterol homeostasis^2,3. ACAT1 has also been implicated in Alzheimer's disease⁴, atherosclerosis⁵ and cancers⁶. Here we report a cryo-electron microscopy structure of human ACAT1 in complex with nevanimibe⁷, an inhibitor that is in clinical trials for the treatment of congenital adrenal hyperplasia. The ACAT1 holoenzyme is a tetramer that consists of two homodimers. Each monomer contains nine transmembrane helices (TMs), six of which (TM4-TM9) form a cavity that accommodates nevanimibe and an endogenous acyl-coenzyme A. This cavity also contains a histidine that has previously been identified as essential for catalytic activity⁸. Our structural data and biochemical analyses provide a physical model to explain the process of cholesterol esterification, as well as details of the interaction between nevanimibe and ACAT1, which may help to accelerate the development of ACAT1 inhibitors to treat related diseases.

The Anti-atherogenic Activity of Beauveriolide Derivative BVD327, a Sterol O-Acyltransferase 2-Selective Inhibitor, in Apolipoprotein E Knockout Mice

The fungal 13-membered cyclodepsipeptides, beauveriolides I and III, were previously reported to be atheroprotective activity in mouse models via inhibiting sterol O-acyltransferase (SOAT) activity. A total of 149 beauveriolide derivatives (BVDs) synthesized combinatorially were evaluated in in silico absorption, distribution, metabolism and excretion (ADME) analysis and inhibitory activity toward the two SOAT isozymes, SOAT1 and SOAT2. Hence, only 11 BVDs exhibited SOAT2-selective inhibition. Among these, we chose BVD327, which had the highest ADME score, for further evaluation. BVD327 administration (50 mg/kg/d, per os (p.o.)) significantly decreased atherosclerotic lesions in the aorta and heart (25.4 ± 6.9 and 20.6 ± 2.9%, respectively) in apolipoprotein E knockout (Apoe-/-) mice fed a cholesterol-enriched diet (0.2% cholesterol and 21% fat) for 12 weeks. These findings indicate that beauveriolide derivatives can be used as anti-atherosclerotic agents.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Remnant cholesterol, coronary atheroma progression and clinical events in statin-treated patients with coronary artery disease

Aim

Remnant cholesterol has been proposed to promote atherosclerotic cardiovascular disease independent of low-density lipoprotein cholesterol, yet the underlying mechanisms are not well understood. We aimed to study the association of remnant cholesterol with coronary atheroma progression and clinical events.

Methods

We analyzed data from 5754 patients with coronary artery disease undergoing serial intravascular ultrasonography who were enrolled in 10 trials examining various medical therapies. Remnant cholesterol was calculated as (non-high-density lipoprotein cholesterol – low-density lipoprotein cholesterol (estimated using the Hopkins–Martin equation)). Changes in percentage atheroma volume and 2-year major adverse cardiovascular events were compared across various levels of remnant cholesterol, and multivariable models were used to assess the independent relationship of remnant cholesterol with changes in percentage atheroma volume.

Results

The mean age was 58.1 ± 9.2 years, 28% were women and 96% received a statin. Percentage atheroma volume progression (changes in percentage atheroma volume > 0) occurred in a linear fashion at on-treatment remnant cholesterol levels of 25 mg/dL or greater. The highest on-treatment remnant cholesterol quartile demonstrated greater percentage atheroma volume progression (+0.53 ± 0.26 vs. –0.15 ± 0.25%, P < 0.001) and 2-year major adverse cardiovascular events (23% vs. 14%, log–rank P < 0.001) compared with the lowest. In multivariable analyses, changes in percentage atheroma volume significantly correlated with on-treatment remnant cholesterol ( P < 0.001] independent of low-density lipoprotein cholesterol, apolipoprotein B, C-reactive protein, high-density lipoprotein cholesterol levels and clinical risk factors. Changes in percentage atheroma volume also significantly correlated with changes in remnant cholesterol following multivariable adjustment.

Conclusions

In statin-treated patients with atherosclerotic cardiovascular disease, remnant cholesterol was associated with coronary atheroma progression regardless of conventional lipid parameters, C-reactive protein or clinical risk factors. Higher remnant cholesterol levels also correlated with higher major adverse cardiovascular events. These data support further investigations into remnant cholesterol-lowering interventions in statin-treated patients harboring residual atherosclerotic cardiovascular disease risk.