APOC3 genetic variation, serum triglycerides, and risk of coronary artery disease in Asian Indians, Europeans, and other ethnic groups

BACKGROUND

Hypertriglyceridemia has emerged as a critical coronary artery disease (CAD) risk factor. Rare loss-of-function (LoF) variants in apolipoprotein C-III have been reported to reduce triglycerides (TG) and are cardioprotective in American Indians and Europeans. However, there is a lack of data in other Europeans and non-Europeans. Also, whether genetically increased plasma TG due to ApoC-III is causally associated with increased CAD risk is still unclear and inconsistent. The objectives of this study were to verify the cardioprotective role of earlier reported six LoF variants of APOC3 in South Asians and other multi-ethnic cohorts and to evaluate the causal association of TG raising common variants for increasing CAD risk.

METHODS

We performed gene-centric and Mendelian randomization analyses and evaluated the role of genetic variation encompassing APOC3 for affecting circulating TG and the risk for developing CAD.

RESULTS

One rare LoF variant (rs138326449) with a 37% reduction in TG was associated with lowered risk for CAD in Europeans (p = 0.007), but we could not confirm this association in Asian Indians (p = 0.641). Our data could not validate the cardioprotective role of other five LoF variants analysed. A common variant rs5128 in the APOC3 was strongly associated with elevated TG levels showing a p-value 2.8 × 10- 424. Measures of plasma ApoC-III in a small subset of Sikhs revealed a 37% increase in ApoC-III concentrations among homozygous mutant carriers than the wild-type carriers of rs5128. A genetically instrumented per 1SD increment of plasma TG level of 15 mg/dL would cause a mild increase (3%) in the risk for CAD (p = 0.042).

CONCLUSIONS

Our results highlight the challenges of inclusion of rare variant information in clinical risk assessment and the generalizability of implementation of ApoC-III inhibition for treating atherosclerotic disease. More studies would be needed to confirm whether genetically raised TG and ApoC-III concentrations would increase CAD risk.

Reversal of hypertriglyceridemia in diabetic BTBR ob/ob mice does not prevent nephropathy

The etiology of diabetic nephropathy in type 2 diabetes is multifactorial. Sustained hyperglycemia is a major contributor, but additional contributions come from the hypertension, obesity, and hyperlipidemia that are also commonly present in patients with type 2 diabetes and nephropathy. The leptin deficient BTBR ob/ob mouse is a model of type 2 diabetic nephropathy in which hyperglycemia, obesity, and hyperlipidemia, but not hypertension, are present. We have shown that reversal of the constellation of these metabolic abnormalities with leptin replacement can reverse the morphologic and functional manifestations of diabetic nephropathy. Here we tested the hypothesis that reversal specifically of the hypertriglyceridemia, using an antisense oligonucleotide directed against ApoC-III, an apolipoprotein that regulates the interactions of VLDL (very low density lipoproteins) with the LDL receptor, is sufficient to ameliorate the nephropathy of Type 2 diabetes. Antisense treatment resulted in reduction of circulating ApoC-III protein levels and resulted in substantial lowering of triglycerides to near-normal levels in diabetic mice versus controls. Antisense treatment did not ameliorate proteinuria or pathologic manifestations of diabetic nephropathy, including podocyte loss. These studies indicate that pathologic manifestations of diabetic nephropathy are unlikely to be reduced by lipid-lowering therapeutics alone, but does not preclude a role for such interventions to be used in conjunction with other therapeutics commonly employed in the treatment of diabetes and its complications.

Downregulation of NK cell activities in Apolipoprotein C-III-induced hyperlipidemia resulting from lipid-induced metabolic reprogramming and crosstalk with lipid-laden dendritic cells

OBJECTIVE

Apolipoprotein C-III (Apoc3) is a key component of triglyceride-rich lipoproteins (TRL). The Apoc3-transgenic mice are characterized by high levels of plasma triglyceride and free fatty acids (FFAs). Apoc3 stimulates human monocytes via activation of the NLRP3 inflammasome. Considering the NK cell downregulation in obese individuals and the possible stimulatory-effects of macrophages, variations of NK cell functions and underlying mechanisms were investigated in mice with Apoc3-induced hyperlipidemia.

METHODS

Variations of activities and glycolipid metabolism in NK cells of the Apoc3-transgenic mice with hyperlipidemia were detected. Molecular mechanisms of lipid-induced metabolic-reprogramming in NK cells were analyzed based on the transcriptome sequencing. Finally, effects of DCs in mice with hyperlipidemia on NK cell functions were determined.

RESULTS

Impaired number and function of NK cells in Apoc3^TG mice was involved with the increased fatty acid oxidation and decreased glycolysis. Increased uptake of FFAs in Apoc3^TG-NK cells contributed to the peroxisome proliferator-activated receptor (PPAR) activation and the downstream PTEN-AKT-mTOR/FOXO1 signaling pathway. Inhibition of PPAR or CPT1α only partly reversed the IFN-γ production of Apoc3^TG-NK cells, but completely restored IFN-γ secretion by palmitic acid-treated NK cells ex vivo, indicating that other factors contributed to the Apoc3^TG-NK cell downregulation. Meanwhile, Apoc3^TG-DCs, which contained more lipids in the cytoplasm, depended on reactive oxygen species (ROS) to increase the expressions PD-L1, TGF-β1, and NKG2D ligands and suppress NK cell activities. DCs of the Apoc3^TG-CD36^-/+ hybrid mice with less intracellular lipids and ROS production could not inhibit NK cells, indicating that intracellular FFAs promoted the immune-modulatory function of DCs.

CONCLUSIONS

The downregulation of NK cell activities in individuals with Apoc3-induced hyperlipidemia was due to the increased fatty acid oxidation in NK cells and the bystander suppression caused by lipid-laden DCs. The dual recovery function of NK cells and DCs would improve the prognosis of patients with metabolic syndrome.

Apolipoprotein C3 aggravates diabetic nephropathy in type 1 diabetes by activating the renal TLR2/NF-κB pathway

OBJECTIVE

Apolipoprotein C3 (ApoC3) is a regulator of triglyceride metabolism and inflammation, and its plasma levels are positively correlated with the progression of diabetic nephropathy (DN) in patients. However, the role and underlying mechanism of ApoC3 in DN remain unclear.

METHODS

Diabetes was induced in ApoC3 transgenic (Tg) and knockout (KO) mice by injection of streptozotocin. We studied the effect of ApoC3 on type 1 DN after 4 months of diabetes. Plasma glucose and lipid levels, renal function parameters and inflammation- and fibrogenesis-related gene and protein expression levels were studied. In vitro, human mesangial cells (HMCs) were incubated with high levels of glucose or/and triglyceride-rich lipoproteins (TRLs) with a high or low ApoC3 content isolated from Tg or wild-type (WT) mice, respectively, to explore the mechanisms of ApoC3 on development of DN.

RESULTS

We found that compared to WT mice, Tg mice exhibited hypertriglyceridemia (HTG), aggravated early renal function injury and inflammation, enlarged glomerular and mesangial surface areas, renal lipid deposition and elevated fibrogenesis-related gene expression levels after 4 months of diabetes. ApoC3 overexpression activated the renal Toll-like receptor 2 (TLR2) and nuclear factor-κB (NF-κB) signaling pathways and increased the renal gene and protein expression levels of the downstream inflammatory factors TNF-α, VCAM-1 and MCP-1. Unfortunately, we did not find that ApoC3 deficiency had an obvious protective effect against DN. In vitro, we found that TRLs with a high ApoC3 content increased the gene and protein expression levels of inflammation- and fibrogenesis-related factors in HMCs compared to those following administration of the same concentration of TRLs with a low ApoC3 content. These effects of ApoC3 were inhibited by blockade of TLR2 or NF-κB.

CONCLUSIONS

These findings suggest that ApoC3 aggravates early-stage DN by activating the renal TLR2/NF-κB pathway which is partially independent of HTG.

Apolipoprotein CIII Is an Important Piece in the Type-1 Diabetes Jigsaw Puzzle

It is well known that type-2 diabetes mellitus (T2D) is increasing worldwide, but also the autoimmune form, type-1 diabetes (T1D), is affecting more people. The latest estimation from the International Diabetes Federation (IDF) is that 1.1 million children and adolescents below 20 years of age have T1D. At present, we have no primary, secondary or tertiary prevention or treatment available, although many efforts testing different strategies have been made. This review is based on the findings that apolipoprotein CIII (apoCIII) is increased in T1D and that in vitro studies revealed that healthy β-cells exposed to apoCIII became apoptotic, together with the observation that humans with higher levels of the apolipoprotein, due to mutations in the gene, are more susceptible to developing T1D. We have summarized what is known about apoCIII in relation to inflammation and autoimmunity in in vitro and in vivo studies of T1D. The aim is to highlight the need for exploring this field as we still are only seeing the top of the iceberg.

Association between APOC3 polymorphisms and non-alcoholic fatty liver disease risk: a meta-analysis

BACKGROUND AND AIM

The apolipoprotein C3 (APOC3) polymorphism has been reported to predispose to non-alcoholic fatty liver disease (NAFLD). However, the results remain inconclusive. This meta-analysis aimed to provide insights into the association between APOC3 polymorphisms and NAFLD risk.

METHODS

Studies with terms "NALFD" and "APOC3" were retrieved from PubMed, Web of Science, CNKI and Wanfang databases up to August 1, 2019. Pooled odds ratio (OR) and 95% confidence interval (95% CI) for the association of APOC3 polymorphisms and NAFLD risk were calculated using fixed and random-effects models.

RESULTS

A total of twelve studies from eleven articles were included. Of them, eight studies (1750 cases and 2181 controls) reported the strong association of variant rs2854116 with NAFLD and six studies (1523 cases and 1568 controls) found the association of rs2854117 polymorphism with NAFLD. Overall, a statistically significant association between rs2854116 polymorphism of APOC3 gene and NAFLD risk was found only under dominant model. However, association of rs2854117 polymorphism with NAFLD risk was not detected under all four genetic models. In sub-group analysis of NAFLD subjects based on country, no association among them in China was detected. Besides, four studies analyze the association between the two polymorphisms and clinical characteristics in all subjects or NAFLD patients, and we also failed detect any association between the wild carriers and variant carriers.

CONCLUSION

The meta-analyses suggests that the rs2854116 polymorphism but not rs2854117 polymorphism in APOC3 gene might be a risk factor for NAFLD among Asians. That is, individuals with CT+CC genotype have higher risk of developing NAFLD. However, studies with sufficient sample size are needed for the further validation.

ApoCIII: A multifaceted protein in cardiometabolic disease

ApoCIII has a well-recognized role in triglyceride-rich lipoproteins metabolism. A considerable amount of data has clearly highlighted that high levels of ApoCIII lead to hypertriglyceridemia and, thereby, may influence the risk of cardiovascular disease. However, recent findings indicate that ApoCIII might also act beyond lipid metabolism. Indeed, ApoCIII has been implicated in other physiological processes such as glucose homeostasis, monocyte adhesion, activation of inflammatory pathways, and modulation of the coagulation cascade. As the inhibition of ApoCIII is emerging as a new promising therapeutic strategy, the complete understanding of multifaceted pathophysiological role of this apoprotein may be relevant. Therefore, the purpose of this work is to review available evidences not only related to genetics and biochemistry of ApoCIII, but also highlighting the role of this apoprotein in triglyceride and glucose metabolism, in the inflammatory process and coagulation cascade as well as in cardiovascular disease.

miR-383 ameliorates high glucose-induced β-cells apoptosis and hyperglycemia in high-fat induced diabetic mice

Islet beta-cell dysfunction is an important condition leading to the development of diabetes. Numerous studies have found that miRNA regulates islet β-cell function. In our previous research, the aberrant expression of miR-383 was revealed in type 2 diabetes mellitus (T2DM) serum. Herein, we aimed to assess the function and underlying mechanism of miR-383 in β-cells through in vitro and in vivo experiments. Using high glucose media, the β-cell injury was induced and transfected miR-383 overexpression vector to detect cell function in MIN6. Moreover, miR-383 overexpression lentivirus was administrated into high-fat induced diabetes mice to assess the in vivo effect. Results showed that overexpressing miR-383 reversed the cell apoptosis and oxidative stress, induced by high glucose which targets Toll-like receptors (TLR4) and Apolipoprotein C3 (ApoC3) genes. Furthermore, mechanistic studies demonstrated that miR-383 targeted the TLR4 and ApoC3 3' UTR consequently inhibiting TLR4 and ApoC3 expression in MIN6 cells. Besides, overexpression of miR-383 ameliorated hyperglycemia and pancreatic apoptosis in high-fat induced diabetic mice. Conclusively, miR-383 potentially alleviate pancreatic β-cell injury induced by high glucose and ameliorates high-fat induced diabetes by suppressing TLR4 and ApoC3 expression.

Differentially expressed genes in cotyledon of ewes fed mycotoxins

BACKGROUND

Ergot alkaloids (E+) are mycotoxins produced by the endophytic fungus, Epichloë coenophiala, in tall fescue that are associated with ergotism in animals. Exposure to ergot alkaloids during gestation reduces fetal weight and placental mass in sheep. These reductions are related to vasoconstrictive effects of ergot alkaloids and potential alterations in nutrient transport to the fetus. Cotyledon samples were obtained from eight ewes that were fed E+ (n = 4; E+/E+) or E- (endophyte-free without ergot alkaloids; n = 4; E-/E-) seed during both mid (d 35 to 85) and late (d 85-133) gestation to assess differentially expressed genes associated with ergot alkaloid induced reductions in placental mass and fetal weight, and discover potential adaptive mechanisms to alter nutrient supply to fetus.

RESULTS

Ewes fed E+/E+ fescue seed during both mid and late gestation had 20% reduction in fetal body weight and 33% reduction in cotyledon mass compared to controls (E-/E-). Over 13,000 genes were identified with 110 upregulated and 33 downregulated. Four genes had a |log2FC| > 5 for ewes consuming E+/E+ treatment compared to controls: LECT2, SLC22A9, APOC3, and MBL2. REViGO revealed clusters of upregulated genes associated glucose, carbohydrates, lipid, protein, macromolecular and cellular metabolism, regulation of wound healing and response to starvation. For downregulated genes, no clusters were present, but all enriched GO terms were associated with anion and monocarboxylic acid transport. The complement and coagulation cascade and the peroxisome proliferator-activated receptor signaling pathway were found to be enriched for ewes consuming E+/E+ treatment.

CONCLUSIONS

Consumption of ergot alkaloids during gestation altered the cotyledonary transcriptome specifically related to macronutrient metabolism, wound healing and starvation. These results show that ergot alkaloid exposure upregulates genes involved in nutrient metabolism to supply the fetus with additional substrates in attempts to rescue fetal growth.

Metabolic characterisation of disturbances in the APOC3/triglyceride-rich lipoprotein pathway through sample-based recall by genotype

INTRODUCTION

High plasma triacylglyceride levels are known to be associated with increased risk of atherosclerotic cardiovascular disease. Apolipoprotein C-III (apoC-III) is a key regulator of plasma triacylglyceride levels and is associated with hypertriglyceridemia via a number of pathways. There is consistent evidence for an association of cardiovascular events with blood apoC-III level, with support from human genetic studies of APOC3 variants. As such, apoC-III has been recognised as a potential therapeutic target for patients with severe hypertriglyceridaemia with one of the most promising apoC-III-targeting drugs, volanesorsen, having recently progressed through Phase III trials.

OBJECTIVES

To exploit a rare loss of function variant in APOC3 (rs138326449) to characterise the potential long-term treatment effects of apoC-III targeting interventions on the metabolome.

METHODS

In a recall-by-genotype study, 115 plasma samples were analysed by UHPLC-MS to acquire non-targeted metabolomics data. The study included samples from 57 adolescents and 33 adults. Overall, 12 985 metabolic features were tested for an association with APOC3 genotype.

RESULTS

161 uniquely annotated metabolites were found to be associated with rs138326449(APOC3). The highest proportion of associated metabolites belonged to the acyl-acyl glycerophospholipid and triacylglyceride metabolite classes. In addition to the anticipated (on-target) reduction of metabolites in the triacylglyceride and related classes, carriers of the rare variant exhibited previously unreported increases in levels of a number of metabolites from the acyl-alkyl glycerophospholipid class.

CONCLUSION

Overall, our results suggest that therapies targeting apoC-III may potentially achieve a broad shift in lipid profile that favours better metabolic health.

The next generation of triglyceride-lowering drugs: will reducing apolipoprotein C-III or angiopoietin like protein 3 reduce cardiovascular disease?

PURPOSE OF REVIEW

Apolipoprotein C-III (ApoC-III) and angiopoietin like protein 3 (angptl3) have emerged as key regulators of triglyceride metabolism. Based on Mendelian randomisation studies, novel therapeutic strategies inhibiting these proteins using monoclonal antibodies or gene silencing techniques might reduce residual cardiovascular disease (CVD) risk in dyslipidemic patients. This article aims to review the role of apoC-III and angptl3 in triglyceride metabolism and combine early clinical evidence of CVD reducing potential of these new therapeutic targets.

RECENT FINDINGS

Angptl3 inhibition by mAb or antisense therapy has recently completed phase I and II studies, respectively and demonstrate robust apolipoprotein B (apoB) lowering up to 46%. Volanesorsen is an antisense therapy approved for patients with extremely elevated plasma triglyceride levels in which it showed no consistent apoB reduction. However, the GalNAc-conjugated oligonucleotide showed moderate (up to ∼30%) apoB reduction in a phase 1/2a dose-finding study.

SUMMARY

Angptl3 and apoC-III are novel targets in lipoprotein metabolism that reduce triglycerides when inhibited. The expected CVD risk reduction may be mediated through reduced triglyceride-rich lipoprotein particle number, reflected by apoB, rather than triglyceride reduction per se. Limited human evidence shows that apoC-III and angptl3 inhibition both potently lower triglycerides, but since angptl3 inhibition reduces apoB more robustly it may be expected to confer more favorable CVD risk reduction.

Apolipoprotein C-II: the re-emergence of a forgotten factor

PURPOSE OF REVIEW

Apolipoprotein C-II (apoC-II) is a critical cofactor for the activation of lipoprotein lipase (LPL), a plasma enzyme that hydrolyzes triglycerides (TG) on TG-rich lipoproteins (TRL). Although apoC-II was first discovered nearly 50 years ago, there is renewed interest in it because of the recent efforts to develop new drugs for the treatment of hypertriglyceridemia (HTG). The main topic of this review will be the development of apoC-II mimetic peptides as a possible new therapy for cardiovascular disease.

RECENT FINDINGS

We first describe the biochemistry of apoC-II and its role in TRL metabolism. We then review the clinical findings of HTG, particularly those related to apoC-II deficiency, and how TG metabolism relates to the development of atherosclerosis. We next summarize the current efforts to develop new drugs for HTG. Finally, we describe recent efforts to make small synthetic apoC-II mimetic peptides for activation of LPL and how these peptides unexpectedly have other mechanisms of action mostly related to the antagonism of the TG-raising effects of apoC-III.

SUMMARY

The role of apoC-II in TG metabolism is reviewed, as well as recent efforts to develop apoC-II mimetic peptides into a novel therapy for HTG.

Association of the polymorphisms of the genes APOC3 (rs2854116), ESR2 (rs3020450), HFE (rs1799945), MMP1 (rs1799750) and PPARG (rs1801282) with lipodystrophy in people living with HIV on antiretroviral therapy: a systematic review

The aim of this study was to perform a systematic review to identify data reported in the literature concerning the association of APOC3 (rs2854116), ESR2 (rs3020450), HFE (rs1799945), MMP1 (rs1799750) and PPARG (rs1801282) polymorphisms with lipodystrophy in people living with HIV (PLWHIV) on antirretroviral therapy. The research was conducted in six databases and the studies were selected in two steps. First, a search was undertaken in the following electronic databases: PubMed, Science Direct, Medline, World Wide Science, Directory of Open Access Journals, Scielo, Lilacs and Medcarib. The titles and abstracts of 24,859 articles were read to select those that match the elegibilty criteria. Five papers that addressed the association of HAART, lipodystrophy and polymorphisms were selected for the review. There was no association between the polymorphisms of the genes APOC3 and PPARG and lipodystrophy. Another study described an association between the variant allele (G) of HFE and protection concerning the development of lipoatrophy (0.02) when compared with the reference allele (C). On the other hand, the variant allele (T) of the ESR2 gene was associated with the development of lipoatrophy (p = 0.007) when compared with the reference allele (C). In addition, the genotype and the variant allele of the gene MMP1 (2G) were associated with lipodystrophy in PLWHIV on HAART (p = 0.0002 and p = 0.0008, respectively). Therefore, further studies with other populations, involving PLWHIV on HAART are necessary to better understand the role of genetic markers, which may be involved in a predisposition to lipodystrophy.

Novel congenital disorder of O-linked glycosylation caused by GALNT2 loss of function

Congenital disorders of glycosylation are a growing group of rare genetic disorders caused by deficient protein and lipid glycosylation. Here, we report the clinical, biochemical, and molecular features of seven patients from four families with GALNT2-congenital disorder of glycosylation (GALNT2-CDG), an O-linked glycosylation disorder. GALNT2 encodes the Golgi-localized polypeptide N-acetyl-d-galactosamine-transferase 2 isoenzyme. GALNT2 is widely expressed in most cell types and directs initiation of mucin-type protein O-glycosylation. All patients showed loss of O-glycosylation of apolipoprotein C-III, a non-redundant substrate for GALNT2. Patients with GALNT2-CDG generally exhibit a syndrome characterized by global developmental delay, intellectual disability with language deficit, autistic features, behavioural abnormalities, epilepsy, chronic insomnia, white matter changes on brain MRI, dysmorphic features, decreased stature, and decreased high density lipoprotein cholesterol levels. Rodent (mouse and rat) models of GALNT2-CDG recapitulated much of the human phenotype, including poor growth and neurodevelopmental abnormalities. In behavioural studies, GALNT2-CDG mice demonstrated cerebellar motor deficits, decreased sociability, and impaired sensory integration and processing. The multisystem nature of phenotypes in patients and rodent models of GALNT2-CDG suggest that there are multiple non-redundant protein substrates of GALNT2 in various tissues, including brain, which are critical to normal growth and development.

Retinoids Repress Human Cardiovascular Cell Calcification With Evidence for Distinct Selective Retinoid Modulator Effects

OBJECTIVE

Retinoic acid (RA) is a ligand for nuclear receptors that modulate gene transcription and cell differentiation. Whether RA controls ectopic calcification in humans is unknown. We tested the hypothesis that RA regulates osteogenic differentiation of human arterial smooth muscle cells and aortic valvular interstitial cells that participate in atherosclerosis and heart valve disease, respectively. Approach and Results: Human cardiovascular tissue contains immunoreactive RAR (RA receptor)-a retinoid-activated nuclear receptor directing multiple transcriptional programs. RA stimulation suppressed primary human cardiovascular cell calcification while treatment with the RAR inhibitor AGN 193109 or RARα siRNA increased calcification. RA attenuated calcification in a coordinated manner, increasing levels of the calcification inhibitor MGP (matrix Gla protein) while decreasing calcification-promoting TNAP (tissue nonspecific alkaline phosphatase) activity. Given that nuclear receptor action varies as a function of distinct ligand structures, we compared calcification responses to cyclic retinoids and the acyclic retinoid peretinoin. Peretinoin suppressed human cardiovascular cell calcification without inducing either secretion of APOC3 (apolipoprotein-CIII), which promotes atherogenesis, or reducing CYP7A1 (cytochrome P450 family 7 subfamily A member 1) expression, which occurred with cyclic retinoids all-trans RA, 9-cis RA, and 13-cis RA. Additionally, peretinoin did not suppress human femur osteoblast mineralization, whereas all-trans RA inhibited osteoblast mineralization.

CONCLUSIONS

These results establish retinoid regulation of human cardiovascular calcification, provide new insight into mechanisms involved in these responses, and suggest selective retinoid modulators, like acyclic retinoids may allow for treating cardiovascular calcification without the adverse effects associated with cyclic retinoids.

Effects of APOC3 Heterozygous Deficiency on Plasma Lipid and Lipoprotein Metabolism

Objective- Apo (apolipoprotein) CIII inhibits lipoprotein lipase (LpL)-mediated lipolysis of VLDL (very-low-density lipoprotein) triglyceride (TG) and decreases hepatic uptake of VLDL remnants. The discovery that 5% of Lancaster Old Order Amish are heterozygous for the APOC3 R19X null mutation provided the opportunity to determine the effects of a naturally occurring reduction in apo CIII levels on the metabolism of atherogenic containing lipoproteins. Approach and Results- We conducted stable isotope studies of VLDL-TG and apoB100 in 5 individuals heterozygous for the null mutation APOC3 R19X (CT) and their unaffected (CC) siblings. Fractional clearance rates and production rates of VLDL-TG and apoB100 in VLDL, IDL (intermediate-density lipoprotein), LDL, apo CIII, and apo CII were determined. Affected (CT) individuals had 49% reduction in plasma apo CIII levels compared with CCs ( P<0.01) and reduced plasma levels of TG (35%, P<0.02), VLDL-TG (45%, P<0.02), and VLDL-apoB100 (36%, P<0.05). These changes were because of higher fractional clearance rates of VLDL-TG and VLDL-apoB100 with no differences in production rates. CTs had higher rates of the conversion of VLDL remnants to LDL compared with CCs. In contrast, rates of direct removal of VLDL remnants did not differ between the groups. As a result, the flux of apoB100 from VLDL to LDL was not reduced, and the plasma levels of LDL-cholesterol and LDL-apoB100 were not lower in the CT group. Apo CIII production rate was lower in CTs compared with CCs, whereas apo CII production rate was not different between the 2 groups. The fractional clearance rates of both apo CIII and apo CII were higher in CTs than CCs. Conclusions- These studies demonstrate that 50% reductions in plasma apo CIII, in otherwise healthy subjects, results in a significantly higher rate of conversion of VLDL to LDL, with little effect on direct hepatic uptake of VLDL. When put in the context of studies demonstrating significant protection from cardiovascular events in individuals with loss of function variants in the APOC3 gene, our results provide strong evidence that therapies which increase the efficiency of conversion of VLDL to LDL, thereby reducing remnant concentrations, should reduce the risk of cardiovascular disease.

Rosa rugosa flavonoids exhibited PPARα agonist-like effects on genetic severe hypertriglyceridemia of mice

ETHNOPHARMACOLOGICAL RELEVANCE

Rosa rugosa Thunb. is a traditional Chinese medicine that was used in the treatment of cardiovascular diseases and relative risk factors such as diabetes, hyperlipidemia, hypertension, and inflammation. Rosa rugosa flavonoids (RRFs) are the main components in Rosa rugosa Thunb. Several studies have demonstrated that RRFs can regulate plasma lipid contents, but the related mechanism of which has not yet been elucidated clearly.

AIM OF THE STUDY

The goal of this study was to clarify the effects of RRFs on triglyceride metabolism and its related mechanisms.

MATERIALS AND METHODS

RRFs were obtained by ethanol extraction from Rosa rugosa Thunb.. Transgenic mice expressing human Apolipoprotein C3 (ApoC3) were used as a mouse model of hypertriglyceridemia. Fenofibrate (FNB), a PPARα agonist, was used as a positive control drug of decreasing high triglyceride. FNB (100 mg/kg) or RRFs (300 mg/kg) were given to the mice by gavage daily. Two weeks later, the changes of plasma lipid levels in the mice were measured by commercial kits, the clearance of triglyceride was evaluated by oral fat load test, and expression of the genes related to lipid β-oxidation and synthesis was detected in the mice livers by real time PCR.

RESULTS

RRFs, as well as FNB, were found to significantly reduce plasma triglyceride (TG) levels in ApoC3 transgenic mice after administration of the drug for two weeks. Plasma lipid clearance rate was increased and lipid content in the mice livers was reduced after administration of RRF. Treatment with RRFs up-regulated mRNA expression of PPARα and its downstream gene of ACOX, while down-regulated mRNA expression of the genes related to fatty acid synthesis (FASN, SREBP-1c, and ACC1). The expression of LPL was raised, while the expression of ApoC3 was decreased, and Foxo1 was inhibited by RRFs in the mice livers.

CONCLUSION

RRFs can reduce plasma TG levels by repressing the expression of ApoC3 and inducing the expression of LPL in liver. RRFs could also reduce triglyceride in hepatocytes through increasing β-oxidation and decreasing synthesis of the lipids. These findings show the potency of further clinical application of RRFs as a hypolipidemic drug for treatment of cardiovascular diseases.

Volanesorsen and Triglyceride Levels in Familial Chylomicronemia Syndrome

BACKGROUND

Familial chylomicronemia syndrome is a rare genetic disorder that is caused by loss of lipoprotein lipase activity and characterized by chylomicronemia and recurrent episodes of pancreatitis. There are no effective therapies. In an open-label study of three patients with this syndrome, antisense-mediated inhibition of hepatic APOC3 mRNA with volanesorsen led to decreased plasma apolipoprotein C-III and triglyceride levels.

METHODS

We conducted a phase 3, double-blind, randomized 52-week trial to evaluate the safety and effectiveness of volanesorsen in 66 patients with familial chylomicronemia syndrome. Patients were randomly assigned, in a 1:1 ratio, to receive volanesorsen or placebo. The primary end point was the percentage change in fasting triglyceride levels from baseline to 3 months.

RESULTS

Patients receiving volanesorsen had a decrease in mean plasma apolipoprotein C-III levels from baseline of 25.7 mg per deciliter, corresponding to an 84% decrease at 3 months, whereas patients receiving placebo had an increase in mean plasma apolipoprotein C-III levels from baseline of 1.9 mg per deciliter, corresponding to a 6.1% increase (P<0.001). Patients receiving volanesorsen had a 77% decrease in mean triglyceride levels, corresponding to a mean decrease of 1712 mg per deciliter (19.3 mmol per liter) (95% confidence interval [CI], 1330 to 2094 mg per deciliter [15.0 to 23.6 mmol per liter]), whereas patients receiving placebo had an 18% increase in mean triglyceride levels, corresponding to an increase of 92.0 mg per deciliter (1.0 mmol per liter) (95% CI, -301.0 to 486 mg per deciliter [-3.4 to 5.5 mmol per liter]) (P<0.001). At 3 months, 77% of the patients in the volanesorsen group, as compared with 10% of patients in the placebo group, had triglyceride levels of less than 750 mg per deciliter (8.5 mmol per liter). A total of 20 of 33 patients who received volanesorsen had injection-site reactions, whereas none of the patients who received placebo had such reactions. No patients in the placebo group had platelet counts below 100,000 per microliter, whereas 15 of 33 patients in the volanesorsen group had such levels, including 2 who had levels below 25,000 per microliter. No patient had platelet counts below 50,000 per microliter after enhanced platelet-monitoring began.

CONCLUSIONS

Volanesorsen lowered triglyceride levels to less than 750 mg per deciliter in 77% of patients with familial chylomicronemia syndrome. Thrombocytopenia and injection-site reactions were common adverse events. (Funded by Ionis Pharmaceuticals and Akcea Therapeutics; APPROACH Clinical Trials.gov number, NCT02211209.).

Predictive Models for the Risk of Dyslipidemia in Adolescents with Essential Arterial Hypertension

Predictive models of comorbidity, dyslipidemic disorders and essential arterial hypertension, in Russian adolescents aged 12 to 18 years (mean 15.48±1.53) were formulated with consideration for biochemical (lipid profiles) and genetic parameters (carrier state of gene polymorphic variants of apolipoprotein genes ApoA1 (-75G/A and +83C/T), ApoB (Ins/Del), ApoC3 (S1/S2), and ApoE (ε2/ε3/ε4). Significant prognostic risk factors for the mentioned comorbid pathologies were lipid metabolism parameters HDL-Ch, LDL-Ch, VLDL-Ch and carrier state of the +83T allele of the ApoA1 gene and Del allele of the ApoB gene. The obtained mathematical model is characterized by high predictive accuracy: the percentage of correct classification or the rate of correct assignment of each participant to the proper group was 96.33%.

Inulin Improves Postprandial Hypertriglyceridemia by Modulating Gene Expression in the Small Intestine

Postprandial hyperlipidemia is an important risk factor for cardiovascular diseases in the context of obesity. Inulin is a non-digestible carbohydrate, known for its beneficial properties in metabolic disorders. We investigated the impact of inulin on postprandial hypertriglyceridemia and on lipid metabolism in a mouse model of diet-induced obesity. Mice received a control or a western diet for 4 weeks and were further supplemented or not with inulin for 2 weeks (0.2 g/day per mouse). We performed a lipid tolerance test, measured mRNA expression of genes involved in postprandial lipid metabolism, assessed post-heparin plasma and muscle lipoprotein lipase activity and measured lipid accumulation in the enterocytes and fecal lipid excretion. Inulin supplementation in western diet-fed mice decreases postprandial serum triglycerides concentration, decreases the mRNA expression levels of Cd36 (fatty acid receptor involved in lipid uptake and sensing) and apolipoprotein C3 (Apoc3, inhibitor of lipoprotein lipase) in the jejunum and increases fecal lipid excretion. In conclusion, inulin improves postprandial hypertriglyceridemia by targeting intestinal lipid metabolism. This work confirms the interest of using inulin supplementation in the management of dyslipidemia linked to obesity and cardiometabolic risk.

A novel index including SNPs for the screening of nonalcoholic fatty liver disease among elder Chinese: A population-based study

Presently noninvasive methods were employed to the diagnosis of nonalcoholic fatty liver disease (NAFLD), including fatty liver index (FLI), hepatic steatosis index (HSI), product of fasting triglyceride and glucose levels (TyG), and single nucleotide polymorphism (SNP), whereas the accuracy of those indexes need to be improved. Our study aimed to investigate the feasibility of a new index comprehensive index (CI), consisting of 6 serum biomarkers and anthropometric parameters through multivariate logistic regression analysis, to the earlier detection of NAFLD, and the diagnostic value of 5 SNPs (S1: rs2854116 of apolipoprotein C3 [APOC3], S2: rs4149267 of ATP-binding cassette transporter [ABCA1], S3: rs13702 of lipoprotein lipase [LPL], S4: rs738409 of protein 3 [patatin-like phospholipase domain containing protein 3 (PNPLA3)], S5: rs780094 of glucokinase regulatory protein gene [GCKR]) for NAFLD were also explored. Area under the receiver operating characteristic curves (AUROC) and Youden index (YI) were calculated to assess the diagnostic value. The AUROC of CI was higher than FLI, HSI, and TyG (CI: 0.897, FLI: 0.873, HSI: 0.855, TyG: 0.793). Therefore, CI might be a better index for the diagnosis of NAFLD. Although there had no statistical significance (P = .123), the AUROC and YI were increased when CI combined with rs2854116 (S1) (AUROC = 0.902, YI = 0.6844). The combination of CI with S1 showed even better diagnostic accuracy than CI, which suggests the potential value of rs2854116 for the diagnosis of NAFLD.

A human APOC3 missense variant and monoclonal antibody accelerate apoC-III clearance and lower triglyceride-rich lipoprotein levels

Recent large-scale genetic sequencing efforts have identified rare coding variants in genes in the triglyceride-rich lipoprotein (TRL) clearance pathway that are protective against coronary heart disease (CHD), independently of LDL cholesterol (LDL-C) levels. Insight into the mechanisms of protection of these variants may facilitate the development of new therapies for lowering TRL levels. The gene APOC3 encodes apoC-III, a critical inhibitor of triglyceride (TG) lipolysis and remnant TRL clearance. Here we report a detailed interrogation of the mechanism of TRL lowering by the APOC3 Ala43Thr (A43T) variant, the only missense (rather than protein-truncating) variant in APOC3 reported to be TG lowering and protective against CHD. We found that both human APOC3 A43T heterozygotes and mice expressing human APOC3 A43T display markedly reduced circulating apoC-III levels. In mice, this reduction is due to impaired binding of A43T apoC-III to lipoproteins and accelerated renal catabolism of free apoC-III. Moreover, the reduced content of apoC-III in TRLs resulted in accelerated clearance of circulating TRLs. On the basis of this protective mechanism, we developed a monoclonal antibody targeting lipoprotein-bound human apoC-III that promotes circulating apoC-III clearance in mice expressing human APOC3 and enhances TRL catabolism in vivo. These data reveal the molecular mechanism by which a missense variant in APOC3 causes reduced circulating TG levels and, hence, protects from CHD. This protective mechanism has the potential to be exploited as a new therapeutic approach to reduce apoC-III levels and circulating TRL burden.

Clarifying complex inheritance: apolipoprotein C3 and atherosclerosis

PURPOSE OF REVIEW

To describe some steps in the progress in the molecular biology of a peptide, apolipoprotein C3; its gene mutations that render individuals susceptible or resistant to developing hyperlipidaemia and atherosclerosis.

RECENT FINDINGS

Data that lead to the development of a new therapeutic agent volanesorsen.

SUMMARY

The agent blocks the function of the mRNA of apolipoprotein C3 and successfully treats severe hypertriglyceridaemia in phase 3 trials (Ionis Pharmaceuticals).

[Association of single nucleotide polymorphism of SIRT1 and APOC3 with nonalcoholic fatty liver disease]

OBJECTIVE

To explore the association of silent information regulator 1( SIRT1) rs12778366 and apolipoprotein C3( APOC3) rs2854116 gene polymorphisms with the susceptibility of nonalcoholic fatty liver disease( NAFLD).

METHODS

One hundred and thirty two NAFLD patients and 252 healthy controls were enrolled in our present study according to the ultrasound diagnosis and physical examination. Venousblood samples were obtained in the morning after an overnight fast, and the samples were used to analyze the biochemical index, relating to hepatic enzymes, blood lipid and blood glucose metabolism. DNA was extracted from whole blood, and polymerase chain reaction( PCR) and mass ARRAY were used to determine the genotypes of target genes.

RESULTS

Compared with TT genotype carriers, the SIRT1 genotype rs12778366 increased the risk of NAFLD, with OR = 1. 126( 95% CI 0. 673-1. 886)( P > 0. 05). The APOC3rs2854116 TC + TT genotype increased the risk of NAFLD compared with CC genotype( OR = 1. 044, 95% CI 0. 601-1. 814, P > 0. 05). The adjusted odds ratios had no significant changes after adjusting for gender, age and BMI. Logistic regression showed that TG, body mass index( BMI), FPG, WC and UA were the independent risk factors for NAFLD( P < 0. 05), but the polymorphisms of SIRT1 rs12778366 and APOC3 rs2854116 had no significant relationship with the risk of NAFLD.

CONCLUSION

SIRT1 rs12778366 and APOC3 rs2854116 polymorphisms were not associated with NAFLD susceptibility.

Effect of hepatic insulin expression on lipid metabolism in diabetic mice

BACKGROUND

Hypertriglyceridemia is a common lipid disorder that is characterized by elevated plasma levels of triglyceride (TG)-rich particles, such as very low-density lipoprotein (VLDL), in poorly controlled diabetes. The aim of the present study was to determine the potential therapeutic effect of hepatic insulin production on hypertriglyceridemia in mice.

METHODS

Mice were induced diabetic and hypertriglyceridemic by streptozotocin (STZ) treatment. Using an adenovirus-mediated gene transfer approach, we delivered rat preproinsulin cDNA into the liver of diabetic mice and then determined plasma TG metabolism. To investigate the mechanism by which hepatic insulin improves TG metabolism, we determined hepatic expression of apolipoprotein C-III (ApoC-III), a structural moiety and functional inhibitor of VLDL-TG catabolism.

RESULTS

Plasma VLDL-TG levels were markedly elevated in STZ-treated mice, and were accompanied by hyperglycemia and hypertriglyceridemia. These metabolic abnormalities were restored to near normal following hepatic insulin production in insulin vector-treated diabetic mice. In contrast, hypertriglyceridemia and hyperglycemia persisted in control vector-treated diabetic animals. Hepatic ApoC-III expression became deregulated secondary to insulin deficiency, contributing to impaired TG metabolism in diabetic mice. Hepatic insulin production suppressed excessive hepatic ApoC-III production to basal levels.

CONCLUSION

Hepatic insulin production is efficacious in correcting hypertriglyceridemia associated with insulin deficiency in diabetic mice.