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Fatty acids are essential for survival, acting as bioenergetic substrates, structural components and signalling molecules. Given their vital role, cells have evolved mechanisms to generate fatty acids from alternative carbon sources, through a process known as de novo lipogenesis (DNL). Despite the importance of DNL, aberrant upregulation is associated with a wide variety of pathologies. Inhibiting core enzymes of DNL, including citrate/isocitrate carrier (CIC), ATP-citrate lyase (ACLY), acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), represents an attractive therapeutic strategy. Despite challenges related to efficacy, selectivity and safety, several new classes of synthetic DNL inhibitors have entered clinical-stage development and may become the foundation for a new class of therapeutics.De novo lipogenesis (DNL) is vital for the maintenance of whole-body and cellular homeostasis, but aberrant upregulation of the pathway is associated with a broad range of conditions, including cardiovascular disease, metabolic disorders and cancers. Here, Steinberg and colleagues provide an overview of the physiological and pathological roles of the core DNL enzymes and assess strategies and agents currently in development to therapeutically target them.

Chronic unresolved inflammation plays a causal role in the development of advanced atherosclerosis, but the mechanisms that prevent resolution in atherosclerosis remain unclear. Here, we use targeted mass spectrometry to identify specialized pro-resolving lipid mediators (SPM) in histologically-defined stable and vulnerable regions of human carotid atherosclerotic plaques. The levels of SPMs, particularly resolvin D1 (RvD1), and the ratio of SPMs to pro-inflammatory leukotriene B 4 (LTB 4 ), are significantly decreased in the vulnerable regions. SPMs are also decreased in advanced plaques of fat-fed Ldlr −/− mice. Administration of RvD1 to these mice during plaque progression restores the RvD1:LTB 4 ratio to that of less advanced lesions and promotes plaque stability, including decreased lesional oxidative stress and necrosis, improved lesional efferocytosis, and thicker fibrous caps. These findings provide molecular support for the concept that defective inflammation resolution contributes to the formation of clinically dangerous plaques and offer a mechanistic rationale for SPM therapy to promote plaque stability. Atherosclerosis progression is linked to inflammatory processes in the blood vessel wall. Here, the authors show that, with the progression of atherosclerosis, the resolution of inflammation is impaired as the result of an imbalance between specialized pro-resolving lipid mediators and leukotrienes.

Increases in calorie consumption and sedentary lifestyles are fuelling a global pandemic of cardiometabolic diseases, including coronary artery disease, diabetes mellitus, cardiomyopathy and heart failure. These lifestyle factors, when combined with genetic predispositions, increase the levels of circulating lipids, which can accumulate in non-adipose tissues, including blood vessel walls and the heart. The metabolism of these lipids produces bioactive intermediates that disrupt cellular function and survival. A compelling body of evidence suggests that sphingolipids, such as ceramides, account for much of the tissue damage in these cardiometabolic diseases. In humans, serum ceramide levels are proving to be accurate biomarkers of adverse cardiovascular disease outcomes. In mice and rats, pharmacological inhibition or depletion of enzymes driving de novo ceramide synthesis prevents the development of diabetes, atherosclerosis, hypertension and heart failure. In cultured cells and isolated tissues, ceramides perturb mitochondrial function, block fuel usage, disrupt vasodilatation and promote apoptosis. In this Review, we discuss the body of literature suggesting that ceramides are drivers — and not merely passengers — on the road to cardiovascular disease. Moreover, we explore the feasibility of therapeutic strategies to lower ceramide levels to improve cardiovascular health.The metabolism of lipids accumulated in blood vessel walls and the heart produces sphingolipids, such as ceramides, which are associated with the development of diabetes mellitus, atherosclerosis, hypertension and heart failure. In this Review, the authors discuss ceramides as drivers of cardiovascular disease and therapeutic strategies to lower plasma and cardiac levels of ceramides.

The 2013 ACC/AHA guidelines on blood cholesterol management were a major shift in the delineation of the main patient groups that could benefit from statin therapy and emphasized the use of higher-intensity statin therapies. In 2016, an expert consensus panel from the ACC recommended the use of nonstatin therapies (ezetimibe and PCSK9 inhibitors) in addition to maximally tolerated statin therapy in individuals whose LDL-cholesterol and non-HDL-cholesterol levels remained above certain thresholds after statin treatment. Given the substantial benefits of statin therapies in both primary and secondary prevention of cardiovascular disease, their long-term safety has become a concern. The potential harmful effects of statin therapy on muscle and liver have been known for some time, but new concerns have emerged regarding the risk of new-onset diabetes mellitus, cognitive impairment and haemorrhagic stroke associated with the use of statins and the risks of achieving very low levels of LDL cholesterol. The increased media attention on the adverse events associated with statins has unfortunately led to statin therapy discontinuation, nonadherence to therapy or concerns about initiating statin therapy. In this Review, we explore the safety of statin therapy in light of the latest evidence and provide clinicians with reassurance about the safety of statins. Overwhelming evidence suggests that the benefits of statin therapy far outweigh any real or perceived risks.

Obesity increases the risk for a number of diseases including cardiovascular diseases and type 2 diabetes. Excess saturated fatty acids (SFAs) in obesity play a significant role in cardiovascular diseases by activating innate immunity responses. However, the mechanisms by which SFAs activate the innate immune system are not fully known. Here we report that palmitic acid (PA), the most abundant circulating SFA, induces myocardial inflammatory injury through the Toll-like receptor 4 (TLR4) accessory protein MD2 in mouse and cell culture experimental models. Md2 knockout mice are protected against PA- and high-fat diet-induced myocardial injury. Studies of cell surface binding, cell-free protein–protein interactions and molecular docking simulations indicate that PA directly binds to MD2, supporting a mechanism by which PA activates TLR4 and downstream inflammatory responses. We conclude that PA is a crucial contributor to obesity-associated myocardial injury, which is likely regulated via its direct binding to MD2. The free fatty acid-mediated inflammatory activities are regulated through TLR4. Here the authors show that palmitic acid binds to MD2, initiating complex formation with TLR4, recruitment of MyD88, and subsequent activation of pro-inflammatory molecules, and that MD2 blockade protects against diet-induced cardiac dysfunction.

Lowering the levels of LDL cholesterol in the plasma has been shown to reduce the risk of atherosclerotic cardiovascular disease (ASCVD). Several other lipoproteins, such as triglyceride-rich lipoproteins, HDL and lipoprotein(a) are associated with atherosclerosis and ASCVD, with strong evidence supporting causality for some. In this Review, we discuss novel and upcoming therapeutic strategies targeting different pathways in lipid metabolism to potentially attenuate the risk of cardiovascular events. Key proteins involved in lipoprotein metabolism, such as PCSK9, angiopoietin-related protein 3, cholesteryl ester transfer protein and apolipoprotein(a), have been identified as viable targets for therapeutic intervention through observational and genetic studies. These proteins can be targeted using a variety of approaches, such as protein inhibition or interference, inhibition of translation at the mRNA level (with the use of antisense oligonucleotides or small interfering RNA), and the introduction of loss-of-function mutations through base editing. These novel and upcoming strategies are complementary to and could work synergistically with existing therapies, or in some cases could potentially replace therapies, offering unprecedented opportunities to prevent ASCVD. Moreover, a major challenge in the prevention and treatment of non-communicable diseases is how to achieve safe, long-lasting reductions in causal exposures. This challenge might be overcome with approaches such as small interfering RNAs or genome editing, which shows how far the field has advanced from when the burden of achieving this goal was placed upon patients through rigorous adherence to daily small-molecule drug regimens.In this Review, the authors discuss current treatment regimens for lowering plasma LDL cholesterol levels to reduce the risk of cardiovascular disease, highlight treatment gaps and challenges, as well as describe opportunities raised by novel available therapies and potential future therapeutic approaches.

Gut microbiota has been suggested to affect lipid metabolism. The objective of this study was to characterize the faecal microbiota signature and both short chain fatty acids (SCFAs) and bile acids (BA) profile of hypercholesterolemic subjects. Microbiota composition, SCFAs, BA and blood lipid profile from male volunteers with hypercholesterolemia (HC) and normocholesterolemia (NC) were determined by 16S rDNA sequencing, HPLC, GC and NMR, respectively. HC subjects were characterized by having lower relative abundance of Anaeroplasma (0.002% vs 0.219%, p-value = 0.026) and Haemophilus (0.041% vs 0.078%, p-value = 0.049), and higher of Odoribacter (0.51% vs 0.16%; p-value = 0.044). Correlation analysis revealed that Anaeroplasma and Haemophilus were associated to an unfavourable lipid profile: they correlated negatively to cholesterol and triglycerides related biomarkers and the ratio total to high density lipoprotein (HDL) cholesterol, and positively to HDL size. Odoribacter displayed an opposite behaviour. Faecal SCFAs profile revealed higher abundance of isobutyric (2.76% vs 0.82%, p-value = 0.049) and isovaleric acid (1.32% vs 0.06%, p-value = 0.016) in HC. Isobutyric acid correlated positively with Odoribacter and lipid parameters indicative of an unfavourable profile. BA profile did not show differences between groups. It was concluded that HC subjects showed a particular faecal bacterial signature and SCFAs profile associated with their lipid profile.

Key Points The role of elevated blood triglycerides as an independent risk factor for cardiovascular disease (CVD) has been debated for more than half a century, but without resolution One of the reasons for this uncertainty is that hypertriglyceridaemia is often associated with decreased HDL-cholesterol levels and an increased number of atherogenic small dense LDL particles Large observational, epidemiological, genetic, and Mendelian randomization studies support the hypothesis that elevated blood triglyceride levels, either fasting or nonfasting, are independently associated with an increased risk of CVD Therapeutic targeting of hypertriglyceridaemia might provide further benefit in reducing CVD and events, in addition to that achieved with LDL-cholesterol lowering Hypertriglyceridaemia is currently treated with lifestyle interventions and with fibrates, which can be combined with high doses of omega-3 fatty acids, but CVD outcome studies have produced inconsistent results Some novel drugs, such as pemafibrate and volanesorsen, are being tested, but clinical data are preliminary The role of hypertriglyceridaemia as a risk factor for coronary artery disease (CAD) is debated. In this Review, Reiner summarizes the causes of hypertriglyceridaemia, and discusses whether elevated blood triglyceride levels are an important and independent risk factor for CAD. Finally, current and emerging management options for hypertriglyceridaemia are detailed. An elevated serum level of LDL cholesterol is a well-known risk factor for cardiovascular disease (CVD), but the role of elevated triglyceride levels is debated. Controversies regarding hypertriglyceridaemia as an independent risk factor for CVD have occurred partly because elevated triglyceride levels are often a component of atherogenic dyslipidaemia — they are associated with decreased levels of HDL cholesterol and increased levels of small dense LDL particles, which are highly atherogenic. Findings from several large studies indicate that elevated levels of triglycerides (either fasting or nonfasting) or, more specifically, triglyceride-rich lipoproteins and their remnants, are independently associated with increased risk of CVD. Possible mechanisms for this association include excessive free fatty acid release, production of proinflammatory cytokines, coagulation factors, and impairment of fibrinolysis. Therapeutic targeting of hypertriglyceridaemia could, therefore, reduce CVD and cardiovascular events, beyond the reduction achieved by LDL-cholesterol lowering. Elevated triglyceride levels are reduced with lifestyle interventions and fibrates, which can be combined with omega-3 fatty acids. Some new drugs are on the horizon, such as volanesorsen (which targets apolipoprotein C-III), pemafibrate, and others. However, CVD outcome studies with triglyceride-lowering agents have produced inconsistent results, meaning that no convincing evidence is available that lowering triglycerides by any approach can reduce mortality.

Familial hypercholesterolaemia is the most commonly encountered genetic condition that predisposes individuals to premature cardiovascular disease. Nevertheless, most patients are undiagnosed, and treatment is often suboptimal even when the diagnosis seems certain. Advances in molecular technologies are reshaping our understanding of this condition, including revision upwards of the population prevalence. Furthermore, the underlying pathophysiological complexity has been exposed by the range of causative genetic loci, breadth of types and classes of rare disease-causing variants, and polygenic basis of the phenotype in many patients. Genetic testing is not always helpful or definitive. Familial hypercholesterolaemia can be envisioned as a group of related disorders, of which the classic ‘textbook’ phenotype is a subset. Features such as clinical stigmata, family history of dyslipidaemia or cardiovascular disease, and presence of a rare pathogenic variant all increase diagnostic certainty. However, even in the absence of these elements, the essential feature remains an elevated level of plasma LDL cholesterol, which alone should prompt a dialogue between the care provider and the patient on lifestyle modification and lipid-lowering therapy as the foundation of a long-term strategy to prevent or delay the onset of cardiovascular disease.

The gene encoding PCSK9 was first identified and linked to the phenotype of familial hypercholesterolaemia approximately 15 years ago. Soon after, studies uncovered the role of PCSK9 in the regulation of LDL-receptor recycling and identified loss-of-function variants of PCSK9 that were associated with low circulating levels of LDL cholesterol (LDL-C) and a reduced risk of coronary artery disease. With amazing rapidity, monoclonal antibodies against PCSK9 were developed and studied in large clinical programmes. These PCSK9 inhibitors lowered plasma LDL-C levels by approximately 60%, even in patients already receiving maximum-dose statin therapy. In the past year, three cardiovascular outcome trials were completed and showed that PCSK9 inhibitors significantly reduce the risk of major vascular events. Reassuringly, this benefit comes with no major offsetting adverse events, such as an excess of myalgias, elevation of hepatic aminotransferases levels in the plasma, incident diabetes mellitus or neurocognitive adverse events. The clinical benefit of PCSK9 inhibitors seen in these trials occurred in the setting of reducing LDL-C levels to unprecedentedly low levels, suggesting that more aggressive LDL-C targets should be adopted. New technologies to inhibit PCSK9 are now being harnessed and might further revolutionize our treatment of dyslipidaemia.