ANGPTL3 Deficiency and Risk of Hepatic Steatosis

Renal Safety Assessment of Lipid-Lowering Drugs: Between Old Certainties and New Questions

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). Quantitative and qualitative changes in plasma lipoprotein profiles are frequently associated with CKD and represent a significant risk factor for CVD in patients with CKD. Guidelines from the European Society of Cardiology and the European Atherosclerosis Society classify CKD as a condition with high or very high cardiovascular risk and set specific low-density lipoprotein cholesterol targets. Conventional lipid-lowering therapies (LLTs), such as statins, ezetimibe, and fibrates, can control CKD-associated dyslipidemia and, to some extent, prevent major atherosclerotic events in patients with CKD, but their use in clinical practice presents challenges because of the potential renal safety concerns. In recent years, novel therapies with the ability to lower both low-density lipoprotein cholesterol and triglycerides have been introduced to the market (e.g., proprotein convertase subtilisin/kexin type 9 inhibitors, bempedoic acid, lomitapide, volanesorsen) to improve our ability to control lipid abnormalities. However, their impact on kidney functionality has not been fully elucidated. The aim of this review was to examine the renal safety profiles of various LLTs, with special reference to novel medications, and to highlight important considerations and guidance for the use of these medications in overt CKD or in patients with some degree of renal function impairment. We underscore the lack of a comprehensive understanding of kidney safety, particularly for novel LLT therapies, and strongly emphasize the importance of future dedicated research to fully assess the safety and efficacy of these agents in patients with kidney abnormalities.

Target Populations for Novel Triglyceride-Lowering Therapies

Lipoprotein lipase regulates triglyceride hydrolysis and contributes to cellular uptake of triglyceride-rich lipoprotein remnants. Multiple pathways modulate lipoprotein lipase activity, which has prompted interest in the development of drugs that increase lipoprotein lipase activity as means to reduce risk for acute pancreatitis, atherosclerotic cardiovascular disease, and metabolic dysfunction-associated steatohepatitis through reduction of circulating triglycerides and remnant cholesterol. The authors provide an overview of the target populations for agents that lower triglycerides and remnant cholesterol through increased lipoprotein lipase activity, the drugs being developed for these indications, including apolipoprotein C-III and angiopoietin-like protein 3, 3/8, and 4 inhibitors, and the epidemiologic and genetic evidence supporting the use of these drugs for the prevention of atherosclerotic cardiovascular disease and acute pancreatitis. In addition, the authors provide a corresponding overview of fibroblast growth factor-21 analogues that share many characteristics with these novel triglyceride-lowering drugs. Apolipoprotein C-III inhibitors, angiopoietin-like protein 3, 3/8, and 4 inhibitors, and fibroblast growth factor-21 analogues have pronounced triglyceride-lowering and remnant cholesterol-lowering effects. In clinical trials, apolipoprotein C-III inhibitors have been shown to lower risk for acute pancreatitis in patients with severe hypertriglyceridemia and are approved for this indication, while fibroblast growth factor-21 analogues reduce hepatic steatosis and fibrosis in patients with metabolic dysfunction-associated steatohepatitis. It remains to be seen whether these novel drugs may lower risk for atherosclerotic cardiovascular disease as well.

Angiopoietin-Like Protein Family-Mediated Functions in Modulating Triglyceride Metabolism and Related Metabolic Diseases

Hypertriglyceridemia, characterized by increased triglyceride (TG) concentrations, is considered the most important risk factor for cardiometabolic disorders, including dyslipidemia, atherosclerotic cardiovascular diseases, and non-alcoholic fatty liver disease (NAFLD). Recently, the angiopoietin-like protein (ANGPTL) family, which comprises ANGPTL1 to ANGPTL8, was confirmed to play an important role in modulating lipoprotein lipase (LPL) activity. However, understanding of the underlying mechanisms remains limited. Importantly, emerging evidence has linked several transcriptional and post-transcriptional factors to the potential alteration of TG metabolism via ANGPTL proteins. This review focused on the similarities and differences in the expression, structural features, and modulatory profile of three ANGPTLs: ANGPTL3, ANGPTL4, and ANGPTL8. In addition, the regulatory functions of those three ANGPTLs in modulating LPL were summarized to provide potential therapeutic and clinical strategies for hypertriglyceridemia and its related cardiometabolic disorders.

Decoding the Therapeutic Target SVEP1: Harnessing Molecular Trait GWASs to Unravel Mechanisms of Human Disease

Although human genetics has substantial potential to illuminate novel disease pathways and facilitate drug development, identifying causal variants and deciphering their mechanisms remain challenging. We believe these challenges can be addressed, in part, by creatively repurposing the results of molecular trait genome-wide association studies (GWASs). In this review, we introduce techniques related to molecular GWASs and unconventionally apply them to understanding SVEP1, a human coronary artery disease risk locus. Our analyses highlight SVEP1's causal link to cardiometabolic disease and glaucoma, as well as the surprising discovery of SVEP1 as the first known physiologic ligand for PEAR1, a critical receptor governing platelet reactivity. We further employ these techniques to dissect the interactions between SVEP1, PEAR1, and the Ang/Tie pathway, with therapeutic implications for a constellation of diseases. This review underscores the potential of molecular GWASs to guide drug discovery and unravel the complexities of human health and disease by demonstrating an integrative approach that grounds mechanistic research in human biology.

ANGPTL3 as a target for treating lipid disorders in type 2 diabetes patients

Type 2 diabetes mellitus (T2DM) is a globally prevalent metabolic disorder, and cardiovascular disease (CVD) is a significant cause of mortality and morbidity in diabetic individuals. In addition to hyperglycemia, lipid abnormalities associated with T2DM play a crucial role in the development of CVD complications. Diabetic dyslipidemia is characterized by elevated levels of triglyceride (TG)-rich lipoproteins and small dense low-density lipoprotein (LDL) particles, reduced high-density lipoprotein (HDL) cholesterol, and impaired HDL function. Angiopoietin protein-like 3 (ANGPTL3) is a liver-derived protein that plays a crucial role in regulating plasma lipoprotein metabolism by inhibiting lipoprotein lipase and influencing lipid levels. Inhibiting ANGPTL3 has shown promising effects in promoting HDL-mediated cholesterol reverse transport and reducing the levels of TG-rich lipoproteins and LDL cholesterol. Here, we explore the potential of ANGPTL3 as a therapeutic target for lipid management in T2DM patients.

Molecular Regulation and Therapeutic Targeting of VLDL Production in Cardiometabolic Disease

There exists a complex relationship between steatotic liver disease (SLD) and atherosclerotic cardiovascular disease (CVD). CVD is a leading cause of morbidity and mortality among individuals with SLD, particularly those with metabolic dysfunction-associated SLD (MASLD), a significant proportion of whom also exhibit features of insulin resistance. Recent evidence supports an expanded role of very low-density lipoprotein (VLDL) in the pathogenesis of CVD in patients, both with and without associated metabolic dysfunction. VLDL represents the major vehicle for exporting neutral lipid from hepatocytes, with each particle containing one molecule of apolipoproteinB100 (APOB100). VLDL production becomes dysregulated under conditions characteristic of MASLD including steatosis and insulin resistance. Insulin resistance not only affects VLDL production but also mediates the pathogenesis of atherosclerotic CVD. VLDL assembly and secretion therefore represents an important pathway in the setting of cardiometabolic disease and offers several candidates for therapeutic targeting, particularly in metabolically complex patients with MASLD at increased risk of atherosclerotic CVD. Here we review the clinical significance as well as the translational and therapeutic potential of key regulatory steps impacting VLDL initiation, maturation, secretion, catabolism, and clearance.

Drug-target Mendelian randomisation applied to metabolic dysfunction-associated steatotic liver disease: opportunities and challenges

Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as the most prevalent cause of chronic liver disease worldwide affecting over one-third of the adult population. Despite the recent evolution of new nomenclature and diagnostic criteria for MASLD, progress in drug development for this condition remains limited. This review highlights the potential of drug-target Mendelian randomisation (MR), a study design that leverages human genetics and genomics, for the discovery, repositioning and safety assessment of drug targets in MASLD. We summarised key aspects of designing and appraising a drug-target MR study, discussing its inherent assumptions and considerations for instrument selection. Furthermore, we presented real-world examples from studies in MASLD which focused on opportunities and challenges in identifying novel drug targets, repositing existing drug targets, informing adjunctive treatments and addressing issues in paediatric MASLD.

Evinacumab in homozygous familial hypercholesterolaemia: long-term safety and efficacy

BACKGROUND AND AIMS

Homozygous familial hypercholesterolaemia (HoFH) is a rare genetic disorder characterized by severely elevated LDL cholesterol (LDL-C) and premature atherosclerotic cardiovascular disease. In the pivotal Phase 3 HoFH trial (NCT03399786), evinacumab significantly decreased LDL-C in patients with HoFH. This study assesses the long-term safety and efficacy of evinacumab in adult and adolescent patients with HoFH.

METHODS

In this open-label, single-arm, Phase 3 trial (NCT03409744), patients aged ≥12 years with HoFH who were evinacumab-naïve or had previously received evinacumab in other trials (evinacumab-continue) received intravenous evinacumab 15 mg/kg every 4 weeks with stable lipid-lowering therapy.

RESULTS

A total of 116 patients (adults: n = 102; adolescents: n = 14) were enrolled, of whom 57 (49.1%) were female. Patients were treated for a median (range) duration of 104.3 (28.3-196.3) weeks. Overall, treatment-emergent adverse events (TEAEs) and serious TEAEs were reported in 93 (80.2%) and 27 (23.3%) patients, respectively. Two (1.7%) deaths were reported (neither was considered related to evinacumab). Three (2.6%) patients discontinued due to TEAEs (none were considered related to evinacumab). From baseline to Week 24, evinacumab decreased mean LDL-C by 43.6% [mean (standard deviation, SD), 3.4 (3.2) mmol/L] in the overall population; mean LDL-C reduction in adults and adolescents was 41.7% [mean (SD), 3.2 (3.3) mmol/L] and 55.4% [mean (SD), 4.7 (2.5) mmol/L], respectively.

CONCLUSIONS

In this large cohort of patients with HoFH, evinacumab was generally well tolerated and markedly decreased LDL-C irrespective of age and sex. Moreover, the efficacy and safety of evinacumab was sustained over the long term.

ANGPTL3 Downregulation Increases Intracellular Lipids by Reducing Energy Utilization

BACKGROUND

ANGPTL3 (angiopoietin-like protein 3) is a circulating protein with a key role in maintaining lipoprotein homeostasis. A monoclonal antibody against ANGPTL3 is an approved and well-tolerated treatment to reduce lipoproteins in familial hypercholesterolemia homozygotes. However, the reduction of hepatic ANGPTL3 synthesis using an antisense oligonucleotide unexpectedly resulted in a dose-dependent increase in liver lipid content and circulating transaminases, resulting in the termination of the clinical trial. Meanwhile, the use of silencing RNAs remains an area of active investigation. Our study sought to investigate whether intracellular downregulation of ANGPTL3 may lead to a primary increase in neutral lipids within the hepatocyte.

METHODS

We downregulated ANGPTL3 by silencing RNA in primary human hepatocytes 3-dimensional spheroids, HepG2/LX-2 3-dimensional spheroids, and in HepG2, Hep3B2, and Huh7 cultured in 2 dimensions.

RESULTS

ANGPTL3 downregulation increased neutral lipids in all models investigated. Interestingly, ANGPTL3 induced lower intracellular deiodinase type 1 protein levels resulting in a reduction in beta-oxidation and causing an increase in triglycerides stored in lipid droplets.

CONCLUSIONS

In conclusion, intracellular ANGPTL3 downregulation by silencing RNA led to an increase in triglycerides content due to a reduction in energy substrate utilization resembling a primary intracellular hepatocyte hypothyroidism.

The first Japanese case with familial combined hypolipidemia without any complications caused by loss-of function variants in ANGPTL3: Case report

Familial combined hypolipidemia, previously known as Familial hypobetalipoproteinemia 2 (FHBL2) is considered as an extremely rare recessive disease. Here, we present the case of familial combined hypolipidemia with homozygous loss-of function (LOF) variants in angiopoietin-like protein 3 (ANGPTL3) ((NM_014495.4) c.439_442del (p.Thr146_Asn147insTer)) using panel sequencing (46 yr male whose LDL cholesterol = 34 mg/dL). The serum level of ANGPTL3 was quite low (undetectable). Despite of extreme decreasing LDL cholesterol, this case did not have any complications as hypobetalipidemia (HBL), such as steatorrhea vomiting, hematological, neuromuscular, or ophthalmological symptoms. In addition, we did not find any systemic atherosclerosis in his carotid arteries and in coronary arteries. Based on the findings suggest that inhibition of ANGPTL3 effectively reduce LDL cholesterol without any apparent side effects, although it is still unclear if he will suffer any disadvantages because of this situation in the future.

ANGPTL3 deficiency impairs lipoprotein production and produces adaptive changes in hepatic lipid metabolism

Angiopoietin-like protein 3 (ANGPTL3) is a hepatically secreted protein and therapeutic target for reducing plasma triglyceride-rich lipoproteins and low-density lipoprotein (LDL) cholesterol. Although ANGPTL3 modulates the metabolism of circulating lipoproteins, its role in triglyceride-rich lipoprotein assembly and secretion remains unknown. CRISPR-associated protein 9 (CRISPR/Cas9) was used to target ANGPTL3 in HepG2 cells (ANGPTL3-/-) whereupon we observed ∼50% reduction of apolipoprotein B100 (ApoB100) secretion, accompanied by an increase in ApoB100 early presecretory degradation via a predominantly lysosomal mechanism. Despite defective particle secretion in ANGPTL3-/- cells, targeted lipidomic analysis did not reveal neutral lipid accumulation in ANGPTL3-/- cells; rather ANGPTL3-/- cells demonstrated decreased secretion of newly synthesized triglycerides and increased fatty acid oxidation. Furthermore, RNA sequencing demonstrated significantly altered expression of key lipid metabolism genes, including targets of peroxisome proliferator-activated receptor α, consistent with decreased lipid anabolism and increased lipid catabolism. In contrast, CRISPR/Cas9 LDL receptor (LDLR) deletion in ANGPTL3-/- cells did not result in a secretion defect at baseline, but proteasomal inhibition strongly induced compensatory late presecretory degradation of ApoB100 and impaired its secretion. Additionally, these ANGPTL3-/-;LDLR-/- cells rescued the deficient LDL clearance of LDLR-/- cells. In summary, ANGPTL3 deficiency in the presence of functional LDLR leads to the production of fewer lipoprotein particles due to early presecretory defects in particle assembly that are associated with adaptive changes in intrahepatic lipid metabolism. In contrast, when LDLR is absent, ANGPTL3 deficiency is associated with late presecretory regulation of ApoB100 degradation without impaired secretion. Our findings therefore suggest an unanticipated intrahepatic role for ANGPTL3, whose function varies with LDLR status.