Apolipoprotein CIII Reduction Protects White Adipose Tissues against Obesity-Induced Inflammation and Insulin Resistance in Mice

Apolipoprotein CIII (apoCIII) is proinflammatory and increases in high-fat diet (HFD)-induced obesity and insulin resistance. We have previously shown that reducing apoCIII improves insulin sensitivity in vivo by complex mechanisms involving liver and brown adipose tissue. In this study the focus was on subcutaneous (SAT) and visceral (VAT) white adipose tissue (WAT). Mice were either given HFD for 14 weeks and directly from start also treated with antisense oligonucleotide (ASO) against apoCIII or given HFD for 10 weeks and HFD+ASO for an additional 14 weeks. Both groups had animals treated with inactive (Scr) ASO as controls and in parallel chow-fed mice were injected with saline. Preventing an increase or lowering apoCIII in the HFD-fed mice decreased adipocytes’ size, reduced expression of inflammatory cytokines and increased expression of genes related to thermogenesis and beiging. Isolated adipocytes from both VAT and SAT from the ASO-treated mice had normal insulin-induced inhibition of lipolysis compared to cells from Scr-treated mice. In conclusion, the HFD-induced metabolic derangements in WATs can be prevented and reversed by lowering apoCIII.

Study of Morphofunctional Parameters of Blood Cells in Ischemic Stroke Using a Genome-wide Research

Biomarkers can play many useful roles in modern neurology. Early diagnosis and immediate therapy are important factors for reducing the degree of brain tissue damage in ischemic stroke, reduces the risk of death from stroke. In the current study, apolipoprotein CIII (ApoCIII), a biomarker of ischemic stroke, was found.

Large-Scale Analysis of Apolipoprotein CIII Glycosylation by Ultrahigh Resolution Mass Spectrometry

Apolipoprotein-CIII (apo-CIII) is a glycoprotein involved in lipid metabolism and its levels are associated with cardiovascular disease risk. Apo-CIII sialylation is associated with improved plasma triglyceride levels and its glycosylation may have an effect on the clearance of triglyceride-rich lipoproteins by directing these particles to different metabolic pathways. Large-scale sample cohort studies are required to fully elucidate the role of apo-CIII glycosylation in lipid metabolism and associated cardiovascular disease. In this study, we revisited a high-throughput workflow for the analysis of intact apo-CIII by ultrahigh-resolution MALDI FT-ICR MS. The workflow includes a chemical oxidation step to reduce methionine oxidation heterogeneity and spectrum complexity. Sinapinic acid matrix was used to minimize the loss of sialic acids upon MALDI. MassyTools software was used to standardize and automate MS data processing and quality control. This method was applied on 771 plasma samples from individuals without diabetes allowing for an evaluation of the expression levels of apo-CIII glycoforms against a panel of lipid biomarkers demonstrating the validity of the method. Our study supports the hypothesis that triglyceride clearance may be regulated, or at least strongly influenced by apo-CIII sialylation. Interestingly, the association of apo-CIII glycoforms with triglyceride levels was found to be largely independent of body mass index. Due to its precision and throughput, the new workflow will allow studying the role of apo-CIII in the regulation of lipid metabolism in various disease settings.

Volanesorsen, an Antisense Oligonucleotide to Apolipoprotein-CIII, Decreases Triglycerides and Increases Lipoprotein Lipase Activity in Partial Lipodystrophy

Partial lipodystrophy syndromes (PL) involve selective deficiency of adipose tissue, with regional deficiency of fat in the lower extremities and preservation or even excess fat in the face and neck. Clinical features typical of PL include severe insulin resistance, diabetes mellitus, hypertriglyceridemia and non-alcoholic fatty liver disease. Apolipoprotein CIII (Apo-CIII) is elevated in PL, and is thought to contribute to high TG by inhibiting lipoprotein lipase (LPL). However, prior studies of this drug in patients with LPL mutations demonstrated LPL-independent mechanisms of TG-lowering. We hypothesized that Volanesorsen, an antisense oligonucleotide (ASO) to apo-CIII, would decrease apo-CIII, increase LPL activity, and lower TG in PL. We further hypothesized that Volanesorsen would improve insulin resistance and glycemia by directing free fatty acids (FFA) into adipose tissue, rather than ectopic sites (e.g. liver) associated with insulin resistance. Five adults with PL and TG ≥500 mg/dL or TG≥200 with A1c >7.0% were enrolled in a 16-week placebo-controlled, randomized, double blind study of Volanesorsen, 300 mg SC weekly, followed by a 1-year open label extension. Here, we report within-subject effects of Volanesorsen lipids, glycemia and lipolysis, before and after 16 weeks of active drug. From week 0 to week 16, apoC-III decreased from 380 (246, 600) to 75 (26, 232) ng/mL, TG decreased from 503 (330, 1040) to 116 (86, 355) mg/dL; and LPL activity measured in post-heparin plasma utilizing the subject’s serum as activator increased from 22.0±3.0 to 35.5±5.9 nEq/ml/min. Free fatty acid turnover (measured by palmitate tracer studies) decreased from 0.41 (0.35, 0.45) to 0.25 (0.23, 0.29) mg/kg/min. There was no change in A1c (8.4±1.2 to 8.3±0.9%), however there was a decrease in HOMA-IR from 26 (20, 54) to 13 (9, 43) and an increase in peripheral insulin sensitivity (glucose infusion rate during euglycemic hyperinsulinemic clamp, 120 mU/m2/min) from 3.6±2.4 to 4.4±1.5 mg/kgFFM/min and in hepatic insulin sensitivity (% suppression of hepatic glucose production during clamp) from 78±19 to 90±13%. Adverse events include injection site reactions and decreased platelets. Volanesorsen decreased apo-CIII and triglycerides, at least in part through an LPL dependent mechanism, and may improve insulin resistance.

Meal-Related Changes in Apolipoprotein Particles After Treatment With an Antisense Oligonucleotide to Apolipoprotein CIII

Background: Lipodystrophy (LD) is defined by partial or complete absence of adipose tissue causing metabolic complications such as high triglycerides (TG). Apolipoprotein CIII (ApoCIII) contributes to high TG by inhibiting lipoprotein lipase (LPL). Measurement of lipoprotein particles using NMR can offer insights into lipid metabolism. Hypothesis: We hypothesized that during a mixed meal test (MMT), clearance of TG-rich lipoprotein particles (TRLP) measured by NMR would increase in LD patients given an antisense oligonucleotide (ASO) to lower ApoCIII. Experimental Design: Five adults with partial LD underwent an MMT (with 18g fat) at week 0 and after 16 weeks (wk) of the ApoCIII ASO. Blood samples were obtained at 0, 30, 60, 120, 180, 240, 300, and 360 minutes (min) and assessed using NMR with the LP4 deconvolution algorithm, which separates TRLPs into 5 size categories: very large (VL), large (L), medium (M), small (S), and very small (VS), all expressed as nmol/L. Major Results: At wk 0, patients had high fasting TG (median 523 mg/dL, IQR 335–1060 mg/dL, normal <150), which decreased after 16wk of ASO[BR([1] (196 mg/dL) Mean TRLP over the 360 min of the MMT was lower after ASO (181.6±14.1 at wk 0, 80.4±2.2 at wk 16). At wk 0, mean L_TRLP during the MMT was 26.8 ± 6.9 and decreased to 9.3±1.3 at wk 16. At wk 0, L_TRLP rose during the MMT to a peak at 180min; at wk 16 there was no rise in L_TRLP during the MMT. Mean S_TRLP during the MMT increased from wk 0 (5.4±3.9) to wk 16 (13.4±10.4). At wk 0, S_TRLP increased minimally during the MMT from 5.2±11.7 at 0 min to 10.9±15.2 at 360 min. At wk 16 there was a more notable rise in S_TRLP in the last 3 hrs of the MMT, from 12.2±15.1 at 0 min to 37.6±28.6 at 360 min. Interpretation of Results and Conclusions: As expected, an ApoCIII ASO lowered fasting and postprandial TG and TRLP. There was minimal rise or fall in any subclass of TRLP during the MMT, either before or after ASO, likely due to the small fat load, which was chosen due to concern for triggering pancreatitis in this at-risk group. The greater post-prandial fluctuation of L_TRLP prior to ASO may represent appearance and disappearance of chylomicron remnants; at wk 16 this was not seen, perhaps due to more rapid clearance of chylomicron remnants by LPL. The larger increase in S_TRLP at the end of the MMT at wk 16 may reflect more rapid lipolysis of L_TRLP by LPL during ASO treatment, thus generating S_TRLP. Next steps include measuring apoB48 and apoB100 during the MMT to distinguish VLDL from chylomicrons, accruing a larger sample size, and collecting MMT data in healthy controls.

Lowering apolipoprotein CIII protects against high-fat diet–induced metabolic derangements

Increased levels of apolipoprotein CIII (apoCIII), a key regulator of lipid metabolism, result in obesity-related metabolic derangements. We investigated mechanistically whether lowering or preventing high-fat diet (HFD)–induced increase in apoCIII protects against the detrimental metabolic consequences. Mice, first fed HFD for 10 weeks and thereafter also given an antisense (ASO) to lower apoCIII, already showed reduced levels of apoCIII and metabolic improvements after 4 weeks, despite maintained obesity. Prolonged ASO treatment reversed the metabolic phenotype due to increased lipase activity and receptor-mediated hepatic uptake of lipids. Fatty acids were transferred to the ketogenic pathway, and ketones were used in brown adipose tissue (BAT). This resulted in no fat accumulation and preserved morphology and function of liver and BAT. If ASO treatment started simultaneously with the HFD, mice remained lean and metabolically healthy. Thus, lowering apoCIII protects against and reverses the HFD-induced metabolic phenotype by promoting physiological insulin sensitivity.

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.

Apolipoprotein CIII and Angiopoietin-like Protein 8 are Elevated in Lipodystrophy and Decrease after Metreleptin

Context Lipodystrophy syndromes cause hypertriglyceridemia that improves with leptin treatment using metreleptin. Mechanisms causing hypertriglyceridemia and improvements after metreleptin are incompletely understood. Objective Determine relationship of circulating lipoprotein lipase (LPL) modulators with hypertriglyceridemia in healthy controls and in patients with lipodystrophy before and after metreleptin. Methods Cross-sectional comparison of patients with lipodystrophy (generalized lipodystrophy n = 3; partial lipodystrophy n = 11) vs age/sex-matched healthy controls (n = 28), and longitudinal analyses in patients before and after 2 weeks and 6 months of metreleptin. The study was carried out at the National Institutes of Health, Bethesda, Maryland. Outcomes were LPL stimulators apolipoprotein (apo) C-II and apoA-V and inhibitors apoC-III and angiopoietin-like proteins (ANGPTLs) 3, 4, and 8; ex vivo activation of LPL by plasma. Results Patients with lipodystrophy were hypertriglyceridemic and had higher levels of all LPL stimulators and inhibitors vs controls except for ANGPTL4, with >300-fold higher ANGPTL8, 4-fold higher apoC-III, 3.5-fold higher apoC-II, 1.9-fold higher apoA-V, 1.6-fold higher ANGPTL3 (P < .05 for all). At baseline, all LPL modulators except ANGPLT4 positively correlated with triglycerides. Metreleptin decreased apoC-II and apoC-III after 2 weeks and 6 months, and decreased ANGPTL8 after 6 months (P < 0.05 for all). Plasma from patients with lipodystrophy caused higher ex vivo LPL activation vs hypertriglyceridemic control plasma (P < .0001), which did not change after metreleptin. Conclusion Elevations in LPL inhibitors apoC-III and ANGPTL8 may contribute to hypertriglyceridemia in lipodystrophy, and may mediate reductions in circulating and hepatic triglycerides after metreleptin. These therefore are strong candidates for therapies to lower triglycerides in these patients.

Abstract 16511: Isocaloric Fructose Restriction Improves Postprandial Chylomicron and VLDL Excursions in Adolescents With Obesity by Reducing Angiopoietin-Like Protein 3 and Apolipoprotein CIII

Introduction: Delayed postprandial triglyceride-rich lipoprotein (TRL) metabolism is associated with increased atherogenic risk. Dietary fructose is a preferred lipogenic substrate which contributes to NAFLD and dyslipoproteinemia. Hypothesis: Isocaloric fructose restriction reduces postprandial TRL excursions in part by affecting the modulation of lipoprotein lipase (LPL) activity and peripheral clearance rates. Methods: We determined the effect of 9 days of isocaloric fructose restriction on fasting and postprandial TRL metabolism markers in obese Latino and African American children (9-18 years old; n=30) with high habitual sugar consumption (>50 g/d). Metabolic assessments were performed on day 0 and day 10 of isocaloric fructose restriction (starch substituted for sugar, same macronutrient composition). To follow postprandial TRL metabolism, after an initial double-sized meal, single-sized meals (providing 67% of daily calories, 15% protein, 35% fat, 50% carbohydrate) were fed every 30 minutes, with blood sampled every hour for 8 hours. Fructose content of meals reduced from 12% on day 0 to 4% on day 10. Paired t-tests compared change from day 0 to day 10 within each child. Results: Fasting TG, apoCIII, and ANGPTL3 reduced by 25%, 28% and 26% respectively (p <0.01). Postprandial AUC of TG, apoCIII, ANGPTL3, VLDL, chylomicrons (apoB48) reduced by 35%, 34%, 40%, 17%, 19% (p <0.01), while no changes were found in fasting or AUC for ANGPTL4, ANGPTL8 nor LPL mass. Conclusions: Short-term isocaloric fructose restriction improved postprandial chylomicron and VLDL metabolism in children with obesity. Specific and selective improvements in ANGPTL3 and apoCIII suggest differential modulation of LPL activity as a putative mechanism that deserves further exploration.

Apolipoprotein CIII Deficiency Protects Against Atherosclerosis in Knockout Rabbits

Objective: Apo (apolipoprotein) CIII mediates the metabolism of triglyceride (TG)-rich lipoproteins. High levels of plasma apoCIII are positively correlated with the plasma TG levels and increase the cardiovascular risk. However, whether apoCIII is directly involved in the development of atherosclerosis has not been fully elucidated. Approach and Results: To examine the possible roles of apoCIII in lipoprotein metabolism and atherosclerosis, we generated apoCIII KO (knockout) rabbits using ZFN (zinc finger nuclease) technique. On a normal standard diet, apoCIII KO rabbits exhibited significantly lower plasma levels of TG than those of WT (wild type) rabbits while total cholesterol and HDL (high-density lipoprotein) cholesterol levels were unchanged. Analysis of lipoproteins isolated by sequential ultracentrifugation revealed that reduced plasma TG levels in KO rabbits were accompanied by prominent reduction of VLDLs (very-low-density lipoproteins) and IDLs (intermediate-density lipoproteins). In addition, KO rabbits showed faster TG clearance rate after intravenous fat load than WT rabbits. On a cholesterol-rich diet, KO rabbits exhibited constantly and significantly lower levels of plasma total cholesterol and TG than WT rabbits, which was caused by a remarkable reduction of β-VLDLs—the major atherogenic lipoproteins. β-VLDLs of KO rabbits showed higher uptake by cultured hepatocytes and were cleared faster from the circulation than β-VLDLs isolated from WT rabbits. Both aortic and coronary atherosclerosis was significantly reduced in KO rabbits compared with WT rabbits. Conclusions: These results indicate that apoCIII deficiency facilitates TG-rich lipoprotein catabolism, and therapeutic inhibition of apoCIII expression may become a novel means not only for the treatment of hyperlipidemia but also for atherosclerosis.