ANGPTL3 is a novel HDL component that regulates HDL function

BACKGROUND

Angiopoietin-like protein 3 (ANGPTL3) is secreted by hepatocytes and inhibits lipoprotein lipase and endothelial lipase activity. Previous studies reported the correlation between plasma ANGPTL3 levels and high-density lipoprotein (HDL). Recently ANGPTL3 was found to preferentially bind to HDL in healthy human circulation. Here, we examined whether ANGPTL3, as a component of HDL, modulates HDL function and affects HDL other components in human and mice with non-diabetes or type 2 diabetes mellitus.

METHODS

HDL was isolated from the plasma of female non-diabetic subjects and type-2 diabetic mellitus (T2DM) patients. Immunoprecipitation, western blot, and ELISA assays were used to examine ANGPTL3 levels in HDL. Db/m and db/db mice, AAV virus mediated ANGPTL3 overexpression and knockdown models and ANGPTL3 knockout mice were used. The cholesterol efflux capacity induced by HDL was analyzed in macrophages preloaded with fluorescent cholesterol. The anti-inflammation capacity of HDL was assessed using flow cytometry to measure VCAM-1 and ICAM-1 expression levels in TNF-α-stimulated endothelial cells pretreated with HDL.

RESULTS

ANGPTL3 was found to bind to HDL and be a component of HDL in both non-diabetic subjects and T2DM patients. Flag-ANGPTL3 was found in the HDL of transgenic mice overexpressing Flag-ANGPTL3. ANGPLT3 of HDL was positively associated with cholesterol efflux in female non-diabetic controls (r = 0.4102, p = 0.0117) but not in female T2DM patients (r = - 0.1725, p = 0.3224). Lower ANGPTL3 levels of HDL were found in diabetic (db/db) mice compared to control (db/m) mice and were associated with reduced cholesterol efflux and inhibition of VCAM-1 and ICAM-1 expression in endothelial cells (p < 0.05 for all). Following AAV-mediated ANGPTL3 cDNA transfer in db/db mice, ANGPTL3 levels were found to be increased in HDL, and corresponded to increased cholesterol efflux and decreased ICAM-1 expression. In contrast, knockdown of ANGPTL3 levels in HDL by AAV-mediated shRNA transfer led to a reduction in HDL function (p < 0.05 for both). Plasma total cholesterol, total triglycerides, HDL-c, protein components of HDL and the cholesterol efflux function of HDL were lower in ANGPTL3-/- mice than ANGPTL3+/+ mice, suggesting that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL.

CONCLUSION

ANGPTL3 was identified as a component of HDL in humans and mice. ANGPTL3 of HDL regulated cholesterol efflux and the anti-inflammatory functions of HDL in T2DM mice. Both the protein components of HDL and cholesterol efflux capacity of HDL were decreased in ANGPTL3-/- mice. Our findings suggest that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL. Our study contributes to a more comprehensive understanding of the role of ANGPTL3 in lipid metabolism.

Advances in Dyslipidaemia Treatments: Focusing on ApoC3 and ANGPTL3 Inhibitors

Apolipoprotein C3 (apoC3) and angiopoietin-like protein 3 (ANGPTL3) inhibit lipolysis by lipoprotein lipase and may influence the secretion and uptake of various lipoproteins. Genetic studies show that depletion of these proteins is associated with improved lipid profiles and reduced cardiovascular events so it was anticipated that drugs which mimic the effects of loss-of-function mutations would be useful lipid treatments. ANGPTL3 inhibitors were initially developed as a treatment for severe hypertriglyceridaemia including familial chylomicronaemia syndrome (FCS), which is usually not adequately controlled with currently available drugs. However, it was found ANGPTL3 inhibitors were also effective in reducing low-density lipoprotein cholesterol (LDL-C) and they were studied in patients with homozygous familial hypercholesterolaemia (FH). Evinacumab targets ANGPTL3 and reduced LDL-C by about 50% in patients with homozygous FH and it has been approved for that indication. The antisense oligonucleotide (ASO) vupanorsen targeting ANGPTL3 was less effective in reducing LDL-C in patients with moderate hypertriglyceridaemia and its development has been discontinued but the small interfering RNA (siRNA) ARO-ANG3 is being investigated in Phase 2 studies. ApoC3 can be inhibited by the ASO volanesorsen, which reduced triglycerides by >70% in patients with FCS and it was approved for FCS in Europe but not in the United States because of concerns about thrombocytopaenia. Olezarsen is an N-acetylgalactosamine-conjugated ASO targeting apoC3 which appears as effective as volanesorsen without the risk of thrombocytopaenia and is undergoing Phase 3 trials. ARO-APOC3 is an siRNA targeting apoC3 that is currently being investigated in Phase 3 studies.

Minnelide combined with Angptl3 knockout completely protects mice with adriamycin nephropathy via suppression of TGF-β1-Smad2 and p53 pathways

Minimal change disease (MCD) is the common type of nephrotic syndrome in children. There is an urgent need to explore new treatment methods as current treatments have many drawbacks and cause significant side effects. Our group found that Angiopoietin-like protein 3 (Angptl3) is closely related to renal disease and Angptl3 knockout significantly alleviated proteinuria in mice with adriamycin nephropathy (AN), however, some proteinuria was still present. Minnelide is a water-soluble prodrug of triptolide which has been used for the treatment of glomerular diseases. Therefore, this study aimed to investigate whether minnelide, combined with Angptl3 knockout, could completely protect mice with AN and its mechanism. AN was induced in B6;129S5 female mice by tail vein injection of 25 mg/kg of Adriamycin (ADR), and treatment with 200 ug/kg/d of minnelide. The results showed that minnelide combined with Angptl3 knockout completely reduced proteinuria and restored the foot processes in mice with AN. Moreover, in Angptl3 knockout mice with AN, minnelide restored the distribution of nephrin, podocin and cd2ap and reduced inflammatory factors (Tumor necrosis factor alpha (TNF-α), Interleukin-6 (IL-6) and Interleukin-1β (IL-1β)). Through RNA sequencing and related experiments, we found minnelide could ameliorate fibrosis and apoptosis by inhibiting TGF-β1-Smad2 and p53 pathways in Angptl3 knockout mice with AN, respectively. In Angptl3 knockout primary podocytes, triptolide alleviates ADR-induced decreases in nephrin, podocin and cd2ap, upregulation of Bax and downregulation of Bcl-2. Overall, our study shows that minnelide combined with Angptl3 knockout completely protects mice with AN by inhibiting the TGF-β1-smad2 and p53 pathways.

New Therapeutic Approaches to the Treatment of Dyslipidemia 1: ApoC-III and ANGPTL3

Low-density lipoprotein cholesterol (LDL-C)-lowering therapy that increases LDL receptor expression in several ways robustly reduces the risk of atherosclerotic cardiovascular disease (CVD). However, a substantial risk of CVD still remains after intensive LDL-C reduction, which requires new treatment modalities for dyslipidemia and cardiovascular risk management. Triglycerides (TGs) and triglyceride-rich lipoproteins (TRLs) have received attention as indicators of residual cardiovascular risk and as direct causal factors for atherosclerosis and CVDs. Advances in understanding TG and TRL metabolism and their association with clinically evident CVDs have led to the development of novel therapeutic targets, including apolipoprotein C-III (apoC-III) and angiopoietin-like protein 3 (ANGPTL3). Genetic association studies have indicated that both apoC-III and ANGPTL3 play a causal role in the development of atherosclerotic CVD. Both molecules contribute to lipid dysregulation and atherosclerosis primarily by inhibiting lipoprotein lipase; however, recent evidence has shown that novel pathways exist in relation to their lipid-modifying activities. Notably, recent progress in therapeutic approaches, such as monoclonal antibodies or antisense oligonucleotides, has led to several novel therapeutics targeting apoC-III and ANGPTL3. This review summarized the recent updates and discussions related to apoC-III and ANGPTL3 expression.

Hypertriglyceridemia

Mild to moderate hypertriglyceridemia usually results from multiple small-effect variants in genes that control triglyceride metabolism. Hypertriglyceridemia is a critical component of the metabolic syndrome but can also occur secondary to several other conditions or drugs. Hypertriglyceridemia frequently is associated with an increased risk of cardiovascular disease (CVD). Statins are the mainstay of CVD prevention in hypertriglyceridemia, but eicosapentaenoic ethyl esters should be added in very-high-risk individuals. Although fibrates lower triglyceride levels, their role in CVD prevention remains unclear. Familial partial lipodystrophy is another relatively rare cause, although its true incidence is unknown.

New and Emerging Therapies for Dyslipidemia

Atherosclerotic cardiovascular disease (ASCVD) continues to represent a growing global health challenge. Despite guideline-recommended treatment of ASCVD risk, including antihypertensive, high-intensity statin therapy, and antiaggregant agents, high-risk patients, especially those with established ASCVD and patients with type 2 diabetes, continue to experience cardiovascular events. Recent years have brought significant developments in lipid and atherosclerosis research. Several lipid drugs owe their existence, in part, to human genetic evidence. Here, the authors briefly review the mechanisms, the effect on lipid parameters, and safety profiles of some of the most promising new lipid-lowering approaches that will be soon available in our daily clinical practice.

Lipoprotein Lipase: Is It a Magic Target for the Treatment of Hypertriglyceridemia

High levels of triglycerides (TG) and triglyceride-rich lipoproteins (TGRLs) confer a residual risk of cardiovascular disease after optimal low-density lipoprotein cholesterol (LDL-C)-lowering therapy. Consensus has been made that LDL-C is a non-arguable primary target for lipid lowering treatment, but the optimization of TGRL for reducing the remnant risk of cardiovascular diseases is urged. Omega-3 fatty acids and fibrates are used to reduce TG levels, but many patients still have high TG and TGRL levels combined with low high-density lipoprotein concentration that need to be ideally treated. Lipoprotein lipase (LPL) is a key regulator for TGs that hydrolyzes TGs to glycerol and free fatty acids in lipoprotein particles for lipid storage and consumption in peripheral organs. A deeper understanding of human genetics has enabled the identification of proteins regulating the LPL activity, which include the apolipoproteins and angiopoietin-like families. Novel therapeutic approach such as antisense oligonucleotides and monoclonal antibodies that regulate TGs have been developed in recent decades. In this article, we focus on the biology of LPL and its modulators and review recent clinical application, including genetic studies and clinical trials of novel therapeutics. Optimization of LPL activity to lower TG levels could eventually reduce incident atherosclerotic cardiovascular disease in conjunction with successful LDL-C reduction.

New, Novel Lipid-Lowering Agents for Reducing Cardiovascular Risk: Beyond Statins

Statins are the cornerstone of the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD). However, even under optimal statin therapy, a significant residual ASCVD risk remains. Therefore, there has been an unmet clinical need for novel lipid-lowering agents that can target low-density lipoprotein cholesterol (LDL-C) and other atherogenic particles. During the past decade, several drugs have been developed for the treatment of dyslipidemia. Inclisiran, a small interfering RNA that targets proprotein convertase subtilisin/kexin type 9 (PCSK9), shows comparable effects to that of PCSK9 monoclonal antibodies. Bempedoic acid, an ATP citrate lyase inhibitor, is a valuable treatment option for the patients with statin intolerance. Pemafibrate, the first selective peroxisome proliferator-activated receptor alpha modulator, showed a favorable benefit-risk balance in phase 2 trial, but the large clinical phase 3 trial (PROMINENT) was recently stopped for futility based on a late interim analysis. High dose icosapent ethyl, a modified eicosapentaenoic acid preparation, shows cardiovascular benefits. Evinacumab, an angiopoietin-like 3 (ANGPTL3) monoclonal antibody, reduces plasma LDL-C levels in patients with refractory hypercholesterolemia. Novel antisense oligonucleotides targeting apolipoprotein C3 (apoC3), ANGPTL3, and lipoprotein(a) have significantly attenuated the levels of their target molecules with beneficial effects on associated dyslipidemias. Apolipoprotein A1 (apoA1) is considered as a potential treatment to exploit the athero-protective effects of high-density lipoprotein cholesterol (HDL-C), but solid clinical evidence is necessary. In this review, we discuss the mode of action and clinical outcomes of these novel lipid-lowering agents beyond statins.

Impact of oral lipid and glucose tolerance tests on the postprandial concentrations of angiopoietin-like proteins (Angptl) 3 and 4

Background

The postprandial regulation of angiopoietin-like proteins (Angptls) and their expression in adipocytes is poorly characterized.

Objective

Circulating Angptl3 and 4 were analyzed in healthy individuals undergoing either an oral lipid tolerance test (OLTT; n = 98) or an oral glucose tolerance test (OGTT; n = 99). Venous blood was drawn after 0, 2, 4, and 6 h during OLTT and after 0, 1, and 2 h during OGTT. Anthropometric and laboratory parameters were assessed and concentrations of Angptls were quantified by enzyme-linked immunosorbent assay. Angptl gene expression in 3T3-L1 adipocytes and in murine adipose tissues and cellular fractions was analyzed by quantitative real-time PCR.

Results

Angptl3 concentrations significantly decreased while Angptl4 levels continuously increased during OLTT. Both proteins remained unaffected during OGTT. Angptl3 and Angptl4 were expressed in murine subcutaneous and visceral AT with higher mRNA levels in mature adipocytes when compared to the stroma-vascular cell fraction. Both proteins were strongly induced during 3T3-L1 adipocyte differentiation and they were unresponsive to glucose in mature fat cells. Adipocyte Angptl3 (but not Angptl4) mRNA expression was inhibited by the polyunsaturated fatty acids arachidonic acid and docosahexaenoic acid, whereas nine types of dietary fatty acids remained without any effect.

Conclusions

There is evidence of short-time regulation of Angptl3/4 levels upon metabolic stress. Angptl4 expression is high and Angptl3 expression is low in AT and restricted mainly to mature adipocytes without any differences concerning fat compartments. Whereas dietary fatty acids and glucose are without any effect, omega-3/-6-polyunsaturated fatty acids inhibited Anptl3 expression in adipocytes.

Selective targeting of angiopoietin-like 3 (ANGPTL3) with vupanorsen for the treatment of patients with familial partial lipodystrophy (FPLD): results of a proof-of-concept study

BACKGROUND

Familial partial lipodystrophy (FPLD) is a rare disease characterized by selective loss of peripheral subcutaneous fat, associated with dyslipidemia and diabetes mellitus. Reductions in circulating levels of ANGPTL3 are associated with lower triglyceride and other atherogenic lipids, making it an attractive target for treatment of FPLD patients. This proof-of-concept study was conducted to assess the efficacy and safety of targeting ANGPTL3 with vupanorsen in patients with FPLD.

METHODS

This was an open-label study. Four patients with FPLD (two with pathogenic variants in LMNA gene, and two with no causative genetic variant), diabetes (HbA1c ≥ 7.0 % and ≤ 12 %), hypertriglyceridemia (≥ 500 mg/dL), and hepatic steatosis (hepatic fat fraction, HFF ≥ 6.4 %) were included. Patients received vupanorsen subcutaneously at a dose of 20 mg weekly for 26 weeks. The primary endpoint was the percent change from baseline in fasting triglycerides at Week 27. Other endpoints analyzed at the same time point included changes in ANGPTL3, fasting lipids and lipoproteins, insulin secretion/sensitivity, postprandial lipids, and glycemic changes in response to a mixed meal test, HFF measured by MRI, and body composition measured by dual-energy absorptiometry (DEXA).

RESULTS

Baseline mean ± SD fasting triglyceride level was 9.24 ± 4.9 mmol/L (817.8 ± 431.9 mg/dL). Treatment resulted in reduction in fasting levels of triglycerides by 59.9 %, ANGPTL3 by 54.7 %, and in several other lipoproteins/lipids, including very low-density lipoprotein cholesterol by 53.5 %, non-high-density lipoprotein cholesterol by 20.9 %, and free fatty acids (FFA) by 41.7 %. The area under the curve for postprandial triglycerides, FFA, and glucose was reduced by 60 %, 32 %, and 14 %, respectively. Treatment with vupanorsen also resulted in 55 % reduction in adipose tissue insulin resistance index, while other insulin sensitivity indices and HbA1c levels were not changed. Additional investigations into HFF and DEXA parameters suggested dynamic changes in fat partitioning during treatment. Adverse events observed were related to common serious complications associated with diabetes and FPLD. Vupanorsen was well tolerated, and there was no effect on platelet count.

CONCLUSIONS

Although limited, these results suggest that targeting ANGPTL3 with vupanorsen could address several metabolic abnormalities in patients with FPLD.

Proteomic identification of serum proteins to induce osteoconductivity of hydroxyapatite

We performed proteomic analysis of rat serum proteins adsorbed on hydroxyapatite (HAp) and α-alumina (α-Al₂O₃) in order to identify proteins that specifically adsorb onto HAp and control cellular responses. Proteins with either or both molecular weight of 22-32 kDa and computed isoelectric point of 5.0-5.5 were preferentially adsorbed on HAp. In total, 182 proteins were adsorbed on both HAp and α-Al₂O₃, of which 14 were highly enriched on HAp, whereas 68 were adsorbed only on HAp. Therefore, 82 (14+68) proteins were further evaluated by bioinformatics and literature-based analyses. We predicted that hepatocyte growth factor and angiopoietin-like protein 3 (ANGPTL3) are candidate proteins responsible for the osteoconductivity of HAp. Although ANGPTL3 promoted the attachment and spreading of MC3T3-E1 cells, it did not promote their proliferation and differentiation. Our results suggest that specific adsorption of ANGPTL3 on HAp induced osteoconductivity by enhancing the attachment and spreading of osteoblasts.

Vupanorsen, an N-acetyl galactosamine-conjugated antisense drug to ANGPTL3 mRNA, lowers triglycerides and atherogenic lipoproteins in patients with diabetes, hepatic steatosis, and hypertriglyceridaemia

Aims 

Loss-of-function mutations in ANGPTL3 are associated with beneficial effects on lipid and glucose metabolism and reduced risk of coronary artery disease. Vupanorsen (AKCEA-ANGPTL3-L Rx ) is an N-acetyl galactosamine-conjugated antisense oligonucleotide targeted to the liver that selectively inhibits angiopoietin-like 3 (ANGPTL3) protein synthesis.

Methods and results 

This was a double-blind, placebo-controlled, dose-ranging, Phase 2 study. Patients (N =105) with fasting triglycerides >150 mg/dL (>1.7 mmol/L), type 2 diabetes, and hepatic steatosis were treated for 6 months with 40 or 80 mg every 4 weeks (Q4W), or 20 mg every week (QW) of vupanorsen, or placebo given subcutaneously. The primary efficacy endpoint was per cent change in fasting triglycerides from baseline at 6 months. Median baseline triglycerides were 2.84 mmol/L (252 mg/dL). Significant reductions in triglycerides of 36%, 53%, 47%, and in ANGPTL3 of 41%, 59%, 56%, were observed in the 40 mg Q4W, 80 mg Q4W, and 20 mg QW groups, respectively, compared with 16% reduction in triglycerides and 8% increase in ANGPTL3 in placebo. Compared with placebo, vupanorsen 80 mg Q4W reduced apolipoprotein C-III (58%), remnant cholesterol (38%), total cholesterol (19%), non-high-density lipoprotein cholesterol (HDL-C; 18%), HDL-C (24%), and apolipoprotein B (9%). There was no improvement in glycaemic parameters, or hepatic fat fraction. Treatment with vupanorsen was not associated with clinically significant changes in platelet counts, and the most common adverse events were those at the injection site, which were generally mild.

Conclusion 

Vupanorsen results in a favourable lipid/lipoprotein profile and provides a potential strategy for residual cardiovascular risk reduction.

ANGPTL3 and Apolipoprotein C-III as Novel Lipid-Lowering Targets

PURPOSE OF REVIEW

Despite significant progress in plasma lipid lowering strategies, recent clinical trials highlight the existence of residual cardiovascular risk. Angiopoietin-like protein 3 (ANGPTL3) and apolipoprotein C-III (Apo C-III) have been identified as novel lipid-lowering targets.

RECENT FINDINGS

Apo C-III and ANGPTL3 have emerged as novel regulators of triglyceride (TG) and low-density lipoprotein-cholesterol (LDL-C) levels. ANGPTL3 is an inhibitor of lipoprotein lipase (LPL), reducing lipolysis of Apo B-containing lipoproteins. Loss-of-function ANGPLT3 mutations are associated with reduced plasma cholesterol and TG, while novel ANGPLT3 inhibition strategies, including monoclonal antibodies (evinacumab), ANGPLT3 antisense oligonucleotides (IONIS-ANGPTL3-L_Rx), and small interfering RNA (siRNA) silencing techniques (ARO-ANG3), result in increased lipolysis and significant reductions of LDL-C and TG levels in phase I and II clinical trials. Similarly, Apo C-III inhibits LPL while promoting the hepatic secretion of TG-rich lipoproteins and preventing their clearance. Loss-of-function APOC3 mutations have been associated with reduced TG levels. Targeting of Apo C-III with volanesorsen, an APOC3 siRNA, results in significant reduction in plasma TG levels but possibly also increased risk for thrombocytopenia, as recently demonstrated in phase I, II, and III clinical trials. ARO-APOC3 is a novel siRNA-based agent targeting Apo C-III which is currently under investigation with regard to its lipid-lowering efficiency. ANGPTL3 and Apo C-III targeting agents have demonstrated striking lipid-lowering effects in recent clinical trials; however, more thorough safety and efficacy data are required. Here, we evaluate the role of ANGPLT3 and Apo C-III in lipid metabolism, present the latest clinical advances targeting those molecules, and outline the remaining scientific challenges on residual lipid-associated cardiovascular risk.

Local delivery of USC-derived exosomes harboring ANGPTL3 enhances spinal cord functional recovery after injury by promoting angiogenesis

Background

Spinal cord injury is a devastating clinical condition for which there are currently no effective therapeutic options. In the present study, we aim to investigate if the effect of an administered injection of exosomes derived from human urine stem cell (USC-Exo) embedded in hydrogel could improve the spinal cord functional recovery after injury and the underlying mechanism.

Methods

Exosomes were isolated from USC and identified by transmission electron microscopy (TEM) and Western blot. Functional assays in vitro were performed to assess the effects of USC-Exo on tube formation and migration, as well as their regulatory role in the PI3K/AKT signaling pathway activation. A locally administered injection of exosome embedded in hydrogel was used for SCI treatment. The effects of USC-Exo on functional recovery and the role of the candidate protein ANGPTL3 harboring in USC-Exo for promoting angiogenesis in SCI model were assessed.

Results

In the current study, we demonstrate that a locally administered injection of USC-Exo embedded in hydrogel can pass the spinal cord blood-brain barrier and deliver ANGPTL3 to the injured spinal cord region. In addition, the administration of human USC-Exo could enhance spinal cord neurological functional recovery by promoting angiogenesis. The results of mechanistic studies revealed that ANGPTL3 is enriched in USC-Exo and is required for their ability to promote angiogenesis. Functional studies further confirmed that the effects of USC-Exo on angiogenesis are mediated by the PI3K/AKT signaling pathway.

Conclusion

Collectively, our results indicate that USC-Exo serve as a crucial regulator of angiogenesis by delivering ANGPTL3 and may represent a promising novel therapeutic agent for SCI repair.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-020-02078-8.

Evaluation of angiopoietin-like protein 3 (ANGPTL3) levels in polycystic ovary syndrome

AIM

Angiopoietin-like protein 3 (ANGPTL3) is recognized as a regulator of lipid metabolism. However, little is known about its association with insulin resistance in polycystic ovary syndrome (PCOS) setting. The present study aimed to investigate the serum levels of ANGPTL3 and adiponectin in PCOS women compared to healthy controls.

MAIN METHOD

In this study, a total of 175 premenopausal women (117 PCOS and 58 non-PCOS) were enrolled. Serum concentrations of ANGPTL3, adiponectin, fasting insulin, and other hormonal variables were measured using ELISA technique.

KEY FINDINGS

Results showed that adiponectin levels were significantly lower in PCOS group than those of non-PCOS group. However, serum levels of ANGPTL3, high-sensitivity C-reactive protein (hs-CRP), and homocysteine (Hcy) were found to be higher in PCOS patients, when compared to non-PCOS ones. Moreover, serum ANGPTL3 positively correlated with BMI and serum triglyceride, while it inversely correlated with serum HDL-C in PCOS patients.

SIGNIFICANCE

Our results demonstrated that increased levels of ANGPTL3 correlated with insulin resistance and dyslipidemia in PCOS patients, highlighting the need for future studies targeting its role in the pathogenesis of this disease.

A randomized study investigating the safety, tolerability, and pharmacokinetics of evinacumab, an ANGPTL3 inhibitor, in healthy Japanese and Caucasian subjects

BACKGROUND AND AIMS

Evinacumab, an angiopoietin-like protein 3 monoclonal antibody, reduced low-density lipoprotein cholesterol (LDL-C) significantly in a Phase 2 study of patients with homozygous familial hypercholesterolemia. In this double-blind, placebo-controlled Phase 1 study, we compared safety, tolerability, pharmacokinetics, and pharmacodynamics of evinacumab between healthy Japanese and Caucasian adults.

METHODS

Subjects with LDL-C ≥2.6 and <4.1 mmol/L were enrolled to one of four dose cohorts: evinacumab subcutaneous (SC) 300 mg single dose, SC 300 mg once weekly for eight doses, intravenous (IV) 5 mg/kg, or IV 15 mg/kg once every 4 weeks for two doses. Each cohort comprised 24 subjects (12 Japanese; 12 Caucasian), randomized (3:1) to receive evinacumab or placebo within each ethnic group with a 24-week follow-up.

RESULTS

The safety profile of evinacumab (IV and SC) in both ethnicities was comparable with placebo, with no serious or severe treatment-emergent adverse events. Pharmacokinetic profiles were comparable between Japanese and Caucasian subjects across IV and SC groups. Mean calculated LDL-C decreased from baseline with both IV doses, beginning on day 3 up to week 8. Triglyceride changes observed with evinacumab IV were rapid (seen by day 2) and sustained up to week 8. Evinacumab SC doses also reduced LDL-C and triglyceride levels, although lower doses induced smaller changes. Evinacumab (IV and SC) reduced other lipids, including apolipoprotein B, versus placebo.

CONCLUSIONS

In both ethnicities, evinacumab (IV and SC) was generally well tolerated, exhibiting comparable pharmacokinetic profiles. Dose-related reductions in LDL-C and triglycerides were observed with evinacumab in both ethnic groups.

ANGPTL3 inhibits renal cell carcinoma metastasis by inhibiting VASP phosphorylation

Angiopoietin-like proteins (ANGPTLs) comprise a group of proteins that are structurally similar to angiopoietins. In our previous studies, we found that ANGPTL3 can inhibit sorafenib resistance in renal cell carcinoma (RCC). According to bioinformatics analysis based on data in the Cancer Genome Atlas (TCGA), we found that expression of ANGPTL3 was significantly lower in RCC tissues than in adjacent tissues and that disease-free survival and overall survival were significantly shorter in patients with lower ANGPTL3 levels than in those with higher ANGPTL3 levels. Consistent with these results, we demonstrated that RCC tissues exhibited lower ANGPTL3 mRNA and protein expression levels than paired adjacent tissues. Moreover, we found that ANGPTL3 upregulation was associated with better clinical outcomes in RCC patients. ANGPTL3 overexpression inhibited the metastatic ability in RCC cells. Mechanistically, ANGPTL3 binds to vasodilator-stimulated phosphoprotein (VASP) and inhibits its phosphorylation at amino acid 157 in RCC cells. Finally, ANGPTL3 expression and VASP-157 phosphorylation may be combined to predict the prognosis of RCC patients. Overall, our findings describe the role of ANGPTL3 in inhibiting RCC metastasis and thus provide new molecular markers for RCC treatment and prognosis.

Angiopoietin-like protein 3 markedly enhanced in the hyperlipidemia related proteinuria

BACKGROUND

Angiopoietin-like protein 3(ANGPTL3) is well acknowledged as a key regulator of lipid metabolism. Now, there have not been enough data to explain the mechanism of hyperlipidemia related proteinuria. In this study, we hoped to investigate the changes of Angiopoietin-like protein 3(ANGPTL3) levels in hyperlipidemia patients with different proteinuria levels.

METHODS

Seventy-one patients with hyperlipidemia were selected, who were hospitalized in Gansu Provincial People's Hospital from September 2016 to September 2017, and 20 healthy people in the physical examination center were selected. We combed through medical history and conducted clinical biochemical indicators of blood urea nitrogen (BUN), serum creatinine (SCr), 24 h urine protein quantitation (24hUPro), cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL) and low detection of density lipoproteins (LDL-C). The concentration of serum ANGPTL3 was measured by ELISA.

RESULTS

1. Serum ANGPTL3 in patients with hyperlipidemia related proteinuria was higher than that in the control group, and the difference was statistically significant (p < 0.05); 2. 24hUPro and BMI (r = 0.321, P = 0.002), TC (r = 0.465, P = 0.000), TG (r = 0.281, P = 0.007), LDL (r = 0.478, P = 0.000) in patients with hyperlipidemia related proteinuria are positively correlated, suggesting that dyslipidemia is related to the occurrence of proteinuria; 3. BMI, TC, TG and LDL in patients with hyperlipidemia related proteinuria were positively correlated with serum ANGPTL3. 4. The 24hUPro of patients with hyperlipidemia related proteinuria was positively correlated with serum ANGPTL3 levels, and BUN and SCr were not associated with serum ANGPTL3 level. 5. There was no significant difference in TC, TG, BMI, 24hUPro and serum ANGPTL3 between the statin-treated and the untreated groups in patients with hyperlipidemia related proteinuria.

CONCLUSIONS

Angiopoietin-like protein 3 markedly enhanced in the hyperlipidemia related proteinuria.

Analysis of circulating angiopoietin-like protein 3 and genetic variants in lipid metabolism and liver health: the DiOGenes study

Background

Angiopoietin-like protein 3 (ANGPTL3), a liver-derived protein, plays an important role in the lipid and lipoprotein metabolism. Using data available from the DiOGenes study, we assessed the link with clinical improvements (weight, plasma lipid, and insulin levels) and changes in liver markers, alanine aminotransferase, aspartate aminotransferase (AST), adiponectin, fetuin A and B, and cytokeratin 18 (CK-18), upon low-calorie diet (LCD) intervention. We also examined the role of genetic variation in determining the level of circulating ANGPTL3 and the relation between the identified genetic markers and markers of hepatic steatosis.

Methods

DiOGenes is a multicenter, controlled dietary intervention where obese participants followed an 8-week LCD (800 kcal/day, using a meal replacement product). Plasma ANGPTL3 and liver markers were measured using the SomaLogic (Boulder, CO) platform. Protein quantitative trait locus (pQTL) analyses assessed the link between more than four million common variants and the level of circulating ANGPTL3 at baseline and changes in levels during the LCD intervention.

Results

Changes in ANGPTL3 during weight loss showed only marginal association with changes in triglycerides (nominal p = 0.02) and insulin (p = 0.04); these results did not remain significant after correcting for multiple testing. However, significant association (after multiple-testing correction) were observed between changes in ANGPTL3 and AST during weight loss (p = 0.004) and between ANGPTL3 and CK-18 (baseline p = 1.03 × 10⁻⁷, during weight loss p = 1.47 × 10⁻¹³). Our pQTL study identified two loci significantly associated with changes in ANGPTL3. One of these loci (the APOA4-APOA5-ZNF259-BUD13 gene cluster) also displayed significant association with changes in CK-18 levels during weight loss (p = 0.007).

Conclusion

We clarify the link between circulating levels of ANGPTL3 and specific markers of liver function. We demonstrate that changes in ANGPLT3 and CK-18 during LCD are under genetic control from trans-acting variants. Our results suggest an extended function of ANGPTL3 in the inflammatory state of liver steatosis and toward liver metabolic processes.

Electronic supplementary material

The online version of this article (10.1186/s12263-018-0597-3) contains supplementary material, which is available to authorized users.

ANGPTL3 is part of the machinery causing dyslipidemia majorily via LPL inhibition in mastitis mice

Previous investigations have shown that inflammation induces changes in lipid and lipoprotein metabolism, and increased expression of angiopoietin-like protein 3 (ANGPTL3) contributes to the development of dyslipidemia. Here we investigated whether there is a correlation between increased ANGPTL3 expression and dyslipidemia in mastitis mice. Thirty mice were divided into two groups: control group and Staphylococcus aureus (S. aureus)-induced mastitis mice group. Changes in the levels of blood lipids [total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C)]; activity of myeloperoxidase (MPO); concentrations of plasma inflammation biomarkers [interferon-γ (IFNγ), tumor necrosis factor α (TNFα), and interleukin-1α (IL-1α)]; concentration of plasma ANGPTL3 protein; lipoprotein lipase (LPL) activities in postheparin plasma; expressions of hepatic N-acetylgalactosaminyltransferase 2 (GALNT2), hepatic ANGPTL3 and adipose LPL were determined. The major results indicated specific pathological mammary tissue changes, elevated MPO activity, reduced GALNT2 mRNA expression, elevated ANGPTL3 mRNA and protein expression and reduced LPL mRNA and protein expression. In plasma samples the S.aureus infused mice displayed elevated ANGPTL3 protein concentration, TG, TC and LDL-C levels, and reduced postheparin LPL activities and HDL-C level. The data suggests that ANGPTL3 is part of the machinery causing dyslipidemia majorily via LPL inhibition in mastitis mice.

Role of angiopoietin-like 3 (ANGPTL3) in regulating plasma level of low-density lipoprotein cholesterol

BACKGROUND AND AIMS

Angiopoietin-like 3 (ANGPTL3) has emerged as a key regulator of lipoprotein metabolism in humans. Homozygous loss of ANGPTL3 function causes familial combined hypolipidemia characterized by low plasma levels of triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). While known effects of ANGPTL3 in inhibiting lipoprotein lipase and endothelial lipase contribute to the low TG and HDL-C, respectively, the basis of low LDL-C remains unclear. Our aim was to explore the role of ANGPTL3 in modulating plasma LDL-C.

METHODS

We performed RNAi-mediated gene silencing of ANGPTL3 in five mouse models and in human hepatoma cells. We validated results by deleting ANGPTL3 gene using the CRISPR/Cas9 genome editing system.

RESULTS

RNAi-mediated Angptl3 silencing in mouse livers resulted in very low TG, HDL-C and LDL-C, a pattern similar to the human phenotype. The effect was observed in wild-type and obese mice, while in hCETP/apolipoprotein (Apo) B-100 double transgenic mice, the silencing decreased LDL-C and TG, but not HDL-C. In a humanized mouse model (Apobec1^-/- carrying human ApoB-100 transgene) deficient in the LDL receptor (LDLR), Angptl3 silencing had minimum effect on LDL-C, suggesting the effect being linked to LDLR. This observation is supported by an additive effect on LDL-C between ANGPTL3 and PCSK9 siRNAs. ANGPTL3 gene deletion induced cellular long-chain TG and ApoB-100 accumulation with elevated LDLR and LDLR-related protein (LRP) 1 expression. Consistent with this, ANGPTL3 deficiency by gene deletion or silencing reduced nascent ApoB-100 secretion and increased LDL/VLDL uptake.

CONCLUSIONS

Reduced secretion and increased uptake of ApoB-containing lipoproteins may contribute to the low LDL-C observed in mice and humans with genetic ANGPTL3 deficiency.

Metreleptin therapy lowers plasma angiopoietin-like protein 3 in patients with generalized lipodystrophy

BACKGROUND

Reduced triglyceride clearance due to impaired lipoprotein lipase-mediated lipolysis contributes to severe hypertriglyceridemia in lipodystrophy. Angiopoietin-like protein 3 (ANGPTL3) and 4 (ANGPTL4) impair clearance of triglycerides by inhibiting lipoprotein lipase. Whether circulating ANGPTL3/4 levels are altered in lipodystrophy and the effects of leptin replacement on these ANGPTLs are unknown.

OBJECTIVE

To examine if ANGPTL3/4 levels are elevated in patients with generalized lipodystrophy and assess the effects of leptin replacement on these ANGPTLs.

METHODS

Preleptin treatment plasma levels of ANGPTLs in patients with generalized lipodystrophy (n = 22) were compared with healthy controls (n = 39) using a post hoc case-control study design. In a prospective open-label study, we studied the effects of metreleptin therapy (16-32 weeks) on plasma ANGPTL3/4 in patients with generalized lipodystrophy.

RESULTS

Plasma ANGPTL3 (geometric mean [95% confidence interval]; 223 [182-275] vs 174 ng/mL [160-189], P = .02) but not ANGPTL4 levels (55 [37-81] vs 44 ng/mL [37-52], P = .26) were higher in patients with lipodystrophy compared with healthy controls. There was a significant decrease in total cholesterol, triglycerides, and glycosylated hemoglobin (A1C) levels following metreleptin therapy. After metreleptin, ANGPTL3 concentrations decreased significantly (223 [182-275] vs 175 ng/mL [144-214], P = .01) with no change in ANGPTL4 (55 [37-81] vs 48 ng/mL [32-73], P = .11).

CONCLUSIONS

These findings suggest that elevated plasma levels of ANGPTL3 in leptin-deficient states is attenuated with leptin therapy.

Correlation between ANGPTL3 expression and tumor angiogenesis in hepatocellular carcinoma

AIM: To investigate the correlation between the expression of angiopoietin-like protein 3 (ANGPTL3) and tumor angiogenesis in hepatocellular carcinoma (HCC).

METHODS: The expression of ANGPTL3 and VEGF proteins in 96 HCC specimens and matched tumor-adjacent specimens was detected by immunohistochemistry and Western blot. Immunohistochemical staining for CD34 was performed in the above specimens to evaluate microvessel density (MVD).

RESULTS: The positive rates of ANGPTL3 and VEGF expression in HCC were significantly higher than that in tumor-adjacent tissue (62.50% vs 32.29%; 81.25% vs 29.17%, both P < 0.05). Active angiogenesis was detected in HCC compared to tumor-adjacent tissue (67.71% vs 31.25%, P < 0.05). Tumor angiogenesis was related with ANGPTL3 expression in HCC. The expression of ANGPTL3 and VEGF protein was significantly up-regulated in HCC compared with matched tumor-adjacent noncancerous tissue.

CONCLUSION: High expression of ANGPTL3 is associated with tumor angiogenesis in HCC.