Lipid Droplet-Derived Monounsaturated Fatty Acids Traffic via PLIN5 to Allosterically Activate SIRT1.

Lipid droplets (LDs) provide a reservoir for triacylglycerol storage and are a central hub for fatty acid trafficking and signaling in cells. Lipolysis promotes mitochondrial biogenesis and oxidative metabolism via a SIRT1/PGC-1α/PPARα-dependent pathway through an unknown mechanism. Herein, we identify that monounsaturated fatty acids (MUFAs) allosterically activate SIRT1 toward select peptide-substrates such as PGC-1α. MUFAs enhance PGC-1α/PPARα signaling and promote oxidative metabolism in cells and animal models in a SIRT1-dependent manner. Moreover, we characterize the LD protein perilipin 5 (PLIN5), which is known to enhance mitochondrial biogenesis and function, to be a fatty-acid-binding protein that preferentially binds LD-derived monounsaturated fatty acids and traffics them to the nucleus following cAMP/PKA-mediated lipolytic stimulation. Thus, these studies identify the first-known endogenous allosteric modulators of SIRT1 and characterize a LD-nuclear signaling axis that underlies the known metabolic benefits of MUFAs and PLIN5.

Insulin Prevents Hypercholesterolemia by Suppressing 12α-Hydroxylated Bile Acids.

BACKGROUND: The risk of cardiovascular disease in type 1 diabetes remains extremely high, despite marked advances in blood glucose control and even the widespread use of cholesterol synthesis inhibitors. Thus, a deeper understanding of insulin regulation of cholesterol metabolism, and its disruption in type 1 diabetes, could reveal better treatment strategies. METHODS: To define the mechanisms by which insulin controls plasma cholesterol levels, we knocked down the insulin receptor, FoxO1, and the key bile acid synthesis enzyme, CYP8B1. We measured bile acid composition, cholesterol absorption, and plasma cholesterol. In parallel, we measured markers of cholesterol absorption and synthesis in humans with type 1 diabetes treated with ezetimibe and simvastatin in a double-blind crossover study. RESULTS: Mice with hepatic deletion of the insulin receptor showed marked increases in 12α-hydroxylated bile acids, cholesterol absorption, and plasma cholesterol. This phenotype was entirely reversed by hepatic deletion of FoxO1. FoxO1 is inhibited by insulin and required for the production of 12α-hydroxylated bile acids, which promote intestinal cholesterol absorption and suppress hepatic cholesterol synthesis. Knockdown of Cyp8b1 normalized 12α-hydroxylated bile acid levels and completely prevented hypercholesterolemia in mice with hepatic deletion of the insulin receptor (n=5-30), as well as mouse models of type 1 diabetes (n=5-22). In parallel, the cholesterol absorption inhibitor, ezetimibe, normalized cholesterol absorption and low-density lipoprotein cholesterol in patients with type 1 diabetes as well as, or better than, the cholesterol synthesis inhibitor, simvastatin (n=20). CONCLUSIONS: Insulin, by inhibiting FoxO1 in the liver, reduces 12α-hydroxylated bile acids, cholesterol absorption, and plasma cholesterol levels. Thus, type 1 diabetes leads to a unique set of derangements in cholesterol metabolism, with increased absorption rather than synthesis. These derangements are reversed by ezetimibe, but not statins, which are currently the first line of lipid-lowering treatment in type 1 diabetes. Taken together, these data suggest that a personalized approach to lipid lowering in type 1 diabetes may be more effective and highlight the need for further studies specifically in this group of patients.

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.

Monoacylglycerol Acyltransferase 1 Knockdown Exacerbates Hepatic Ischemia/Reperfusion Injury in Mice With Hepatic Steatosis.

Nonalcoholic fatty liver disease (NAFLD) is becoming the most common indication for liver transplantation. The growing prevalence of NAFLD not only increases the demand for liver transplantation, but it also limits the supply of available organs because steatosis predisposes grafts to ischemia/reperfusion injury (IRI) and many steatotic grafts are discarded. We have shown that monoacylglycerol acyltransferase (MGAT) 1, an enzyme that converts monoacylglycerol to diacylglycerol, is highly induced in animal models and patients with NAFLD and is an important mediator in NAFLD-related insulin resistance. Herein, we sought to determine whether Mogat1 (the gene encoding MGAT1) knockdown in mice with hepatic steatosis would reduce liver injury and improve liver regeneration following experimental IRI. Antisense oligonucleotides (ASO) were used to knockdown the expression of Mogat1 in a mouse model of NAFLD. Mice then underwent surgery to induce IRI. We found that Mogat1 knockdown reduced hepatic triacylglycerol accumulation, but it unexpectedly exacerbated liver injury and mortality following experimental ischemia/reperfusion surgery in mice on a high-fat diet. The increased liver injury was associated with robust effects on the hepatic transcriptome following IRI including enhanced expression of proinflammatory cytokines and chemokines and suppression of enzymes involved in intermediary metabolism. These transcriptional changes were accompanied by increased signs of oxidative stress and an impaired regenerative response. We have shown that Mogat1 knockdown in a mouse model of NAFLD exacerbates IRI and inflammation and prolongs injury resolution, suggesting that Mogat1 may be necessary for liver regeneration following IRI and that targeting this metabolic enzyme will not be an effective treatment to reduce steatosis-associated graft dysfunction or failure.

Cardiovascular and Metabolic Effects of ANGPTL3 Antisense Oligonucleotides.

BACKGROUND: Epidemiologic and genomewide association studies have linked loss-of-function variants in ANGPTL3, encoding angiopoietin-like 3, with low levels of plasma lipoproteins. METHODS: We evaluated antisense oligonucleotides (ASOs) targeting Angptl3 messenger RNA (mRNA) for effects on plasma lipid levels, triglyceride clearance, liver triglyceride content, insulin sensitivity, and atherosclerosis in mice. Subsequently, 44 human participants (with triglyceride levels of either 90 to 150 mg per deciliter [1.0 to 1.7 mmol per liter] or >150 mg per deciliter, depending on the dose group) were randomly assigned to receive subcutaneous injections of placebo or an antisense oligonucleotide targeting ANGPTL3 mRNA in a single dose (20, 40, or 80 mg) or multiple doses (10, 20, 40, or 60 mg per week for 6 weeks). The main end points were safety, side-effect profile, pharmacokinetic and pharmacodynamic measures, and changes in levels of lipids and lipoproteins. RESULTS: The treated mice had dose-dependent reductions in levels of hepatic Angptl3 mRNA, Angptl3 protein, triglycerides, and low-density lipoprotein (LDL) cholesterol, as well as reductions in liver triglyceride content and atherosclerosis progression and increases in insulin sensitivity. After 6 weeks of treatment, persons in the multiple-dose groups had reductions in levels of ANGPTL3 protein (reductions of 46.6 to 84.5% from baseline, P<0.01 for all doses vs. placebo) and in levels of triglycerides (reductions of 33.2 to 63.1%), LDL cholesterol (1.3 to 32.9%), very-low-density lipoprotein cholesterol (27.9 to 60.0%), non-high-density lipoprotein cholesterol (10.0 to 36.6%), apolipoprotein B (3.4 to 25.7%), and apolipoprotein C-III (18.9 to 58.8%). Three participants who received the antisense oligonucleotide and three who received placebo reported dizziness or headache. There were no serious adverse events. CONCLUSIONS: Oligonucleotides targeting mouse Angptl3 retarded the progression of atherosclerosis and reduced levels of atherogenic lipoproteins in mice. Use of the same strategy to target human ANGPTL3 reduced levels of atherogenic lipoproteins in humans. (Funded by Ionis Pharmaceuticals; ClinicalTrials.gov number, NCT02709850 .).

Novel Reversible Model of Atherosclerosis and Regression Using Oligonucleotide Regulation of the LDL Receptor.

RATIONALE: Animal models have been used to explore factors that regulate atherosclerosis. More recently, they have been used to study the factors that promote loss of macrophages and reduction in lesion size after lowering of plasma cholesterol levels. However, current animal models of atherosclerosis regression require challenging surgeries, time-consuming breeding strategies, and methods that block liver lipoprotein secretion. OBJECTIVE: We sought to develop a more direct or time-effective method to create and then reverse hypercholesterolemia and atherosclerosis via transient knockdown of the hepatic LDLR (low-density lipoprotein receptor) followed by its rapid restoration. METHODS AND RESULTS: We used antisense oligonucleotides directed to LDLR mRNA to create hypercholesterolemia in wild-type C57BL/6 mice fed an atherogenic diet. This led to the development of lesions in the aortic root, aortic arch, and brachiocephalic artery. Use of a sense oligonucleotide replicating the targeted sequence region of the LDLR mRNA rapidly reduced circulating cholesterol levels because of recovery of hepatic LDLR expression. This led to a decrease in macrophages within the aortic root plaques and brachiocephalic artery, that is, regression of inflammatory cell content, after a period of 2 to 3 weeks. CONCLUSIONS: We have developed an inducible and reversible hepatic LDLR knockdown mouse model of atherosclerosis regression. Although cholesterol reduction decreased early en face lesions in the aortic arches, macrophage area was reduced in both early and late lesions within the aortic sinus after reversal of hypercholesterolemia. Our model circumvents many of the challenges associated with current mouse models of regression. The use of this technology will potentially expedite studies of atherosclerosis and regression without use of mice with genetic defects in lipid metabolism.

ApoC-III Glycoforms Are Differentially Cleared by Hepatic TRL (Triglyceride-Rich Lipoprotein) Receptors.

OBJECTIVE: ApoC-III (apolipoprotein C-III) glycosylation can predict cardiovascular disease risk. Higher abundance of disialylated (apoC-III2) over monosialylated (apoC-III1) glycoforms is associated with lower plasma triglyceride levels. Yet, it remains unclear whether apoC-III glycosylation impacts TRL (triglyceride-rich lipoprotein) clearance and whether apoC-III antisense therapy (volanesorsen) affects distribution of apoC-III glycoforms. Approach and Results: To measure the abundance of human apoC-III glycoforms in plasma over time, human TRLs were injected into wild-type mice and mice lacking hepatic TRL clearance receptors, namely HSPGs (heparan sulfate proteoglycans) or both LDLR (low-density lipoprotein receptor) and LRP1 (LDLR-related protein 1). ApoC-III was more rapidly cleared in the absence of HSPG (t1/2=25.4 minutes) than in wild-type animals (t1/2=55.1 minutes). In contrast, deficiency of LDLR and LRP1 (t1/2=56.1 minutes) did not affect clearance of apoC-III. After injection, a significant increase in the relative abundance of apoC-III2 was observed in HSPG-deficient mice, whereas the opposite was observed in mice lacking LDLR and LRP1. In patients, abundance of plasma apoC-III glycoforms was assessed after placebo or volanesorsen administration. Volanesorsen treatment correlated with a statistically significant 1.4-fold increase in the relative abundance of apoC-III2 and a 15% decrease in that of apoC-III1. The decrease in relative apoC-III1 abundance was strongly correlated with decreased plasma triglyceride levels in patients. CONCLUSIONS: Our results indicate that HSPGs preferentially clear apoC-III2. In contrast, apoC-III1 is more effectively cleared by LDLR/LRP1. Clinically, the increase in the apoC-III2/apoC-III1 ratio on antisense lowering of apoC-III might reflect faster clearance of apoC-III1 because this metabolic shift associates with improved triglyceride levels.

Angiotensinogen and Megalin Interactions Contribute to Atherosclerosis-Brief Report.

Objective- AGT (Angiotensinogen) is the unique precursor of the renin-angiotensin system that is sequentially cleaved by renin and ACE (angiotensin-converting enzyme) to produce Ang II (angiotensin II). In this study, we determined how these renin-angiotensin components interact with megalin in kidney to promote atherosclerosis. Approach and Results- AGT, renin, ACE, and megalin were present in the renal proximal convoluted tubules of wild-type mice. Hepatocyte-specific AGT deficiency abolished AGT protein accumulation in proximal tubules and diminished Ang II concentrations in kidney, while renin was increased. Megalin was most abundant in kidney and exclusively present on the apical side of proximal tubules. Inhibition of megalin by antisense oligonucleotides (ASOs) led to ablation of AGT and renin proteins in proximal tubules, while leading to striking increases of urine AGT and renin concentrations, and 70% reduction of renal Ang II concentrations. However, plasma Ang II concentrations were unaffected. To determine whether AGT and megalin interaction contributes to atherosclerosis, we used both male and female low-density lipoprotein receptor-/- mice fed a saturated fat-enriched diet and administered vehicles (PBS or control ASO) or megalin ASO. Inhibition of megalin did not affect plasma cholesterol concentrations, but profoundly reduced atherosclerotic lesion size in both male and female mice. Conclusions- These results reveal a regulatory role of megalin in the intrarenal renin-angiotensin homeostasis and atherogenesis, positing renal Ang II to be an important contributor to atherosclerosis that is mediated through AGT and megalin interactions.

An inclusive Research Education Community (iREC): Impact of the SEA-PHAGES program on research outcomes and student learning.

Engaging undergraduate students in scientific research promises substantial benefits, but it is not accessible to all students and is rarely implemented early in college education, when it will have the greatest impact. An inclusive Research Education Community (iREC) provides a centralized scientific and administrative infrastructure enabling engagement of large numbers of students at different types of institutions. The Science Education Alliance-Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) is an iREC that promotes engagement and continued involvement in science among beginning undergraduate students. The SEA-PHAGES students show strong gains correlated with persistence relative to those in traditional laboratory courses regardless of academic, ethnic, gender, and socioeconomic profiles. This persistent involvement in science is reflected in key measures, including project ownership, scientific community values, science identity, and scientific networking.

Hepatic monoacylglycerol acyltransferase 1 is induced by prolonged food deprivation to modulate the hepatic fasting response.

During prolonged fasting, the liver plays a central role in maintaining systemic energy homeostasis by producing glucose and ketones in processes fueled by oxidation of fatty acids liberated from adipose tissue. In mice, this is accompanied by transient hepatic accumulation of glycerolipids. We found that the hepatic expression of monoacylglycerol acyltransferase 1 (Mogat1), an enzyme with monoacylglycerol acyltransferase (MGAT) activity that produces diacyl-glycerol from monoacylglycerol, was significantly increased in the liver of fasted mice compared with mice given ad libitum access to food. Basal and fasting-induced expression of Mogat1 was markedly diminished in the liver of mice lacking the transcription factor PPARα. Suppressing Mogat1 expression in liver and adipose tissue with antisense oligonucleotides (ASOs) reduced hepatic MGAT activity and triglyceride content compared with fasted controls. Surprisingly, the expression of many other PPARα target genes and PPARα activity was also decreased in mice given Mogat1 ASOs. When mice treated with control or Mogat1 ASOs were gavaged with the PPARα ligand, WY-14643, and then fasted for 18 h, WY-14643 administration reversed the effects of Mogat1 ASOs on PPARα target gene expression and liver triglyceride content. In conclusion, Mogat1 is a fasting-induced PPARα target gene that may feed forward to regulate liver PPARα activity during food deprivation.

Antisense oligonucleotides targeting translation inhibitory elements in 5' UTRs can selectively increase protein levels.

A variety of diseases are caused by deficiencies in amounts or activity of key proteins. An approach that increases the amount of a specific protein might be of therapeutic benefit. We reasoned that translation could be specifically enhanced using trans-acting agents that counter the function of negative regulatory elements present in the 5' UTRs of some mRNAs. We recently showed that translation can be enhanced by antisense oligonucleotides (ASOs) that target upstream open reading frames. Here we report the amount of a protein can also be selectively increased using ASOs designed to hybridize to other translation inhibitory elements in 5' UTRs. Levels of human RNASEH1, LDLR, and ACP1 and of mouse ACP1 and ARF1 were increased up to 2.7-fold in different cell types and species upon treatment with chemically modified ASOs targeting 5' UTR inhibitory regions in the mRNAs encoding these proteins. The activities of ASOs in enhancing translation were sequence and position dependent and required helicase activity. The ASOs appear to improve the recruitment of translation initiation factors to the target mRNA. Importantly, ASOs targeting ACP1 mRNA significantly increased the level of ACP1 protein in mice, suggesting that this approach has therapeutic and research potentials.

Antisense Inhibition of Apolipoprotein C-III in Patients with Hypertriglyceridemia.

BACKGROUND: Apolipoprotein C-III (APOC3) is a key regulator of plasma triglyceride levels. Elevated triglyceride levels are associated with a risk of adverse cardiovascular events and pancreatitis. ISIS 304801 is a second-generation antisense inhibitor of APOC3 synthesis. METHODS: We conducted a randomized, double-blind, placebo-controlled, dose-ranging, phase 2 study to evaluate ISIS 304801 in untreated patients with fasting triglyceride levels between 350 mg per deciliter (4.0 mmol per liter) and 2000 mg per deciliter (22.6 mmol per liter) (ISIS 304801 monotherapy cohort), as well as in patients receiving stable fibrate therapy who had fasting triglyceride levels between 225 mg per deciliter (2.5 mmol per liter) and 2000 mg per deciliter (ISIS 304801-fibrate cohort). Eligible patients were randomly assigned to receive either ISIS 304801, at doses ranging from 100 to 300 mg, or placebo, once weekly for 13 weeks. The primary outcome was the percentage change in APOC3 level from baseline. RESULTS: A total of 57 patients were treated in the ISIS 304801 monotherapy cohort (41 received active agent, and 16 received placebo), and 28 patients were treated in the ISIS 304801-fibrate cohort (20 received active agent, and 8 received placebo). The mean (±SD) baseline triglyceride levels in the two cohorts were 581±291 mg per deciliter (6.6±3.3 mmol per liter) and 376±188 mg per deciliter (4.2±2.1 mmol per liter), respectively. Treatment with ISIS 304801 resulted in dose-dependent and prolonged decreases in plasma APOC3 levels when the drug was administered as a single agent (decreases of 40.0±32.0% in the 100-mg group, 63.8±22.3% in the 200-mg group, and 79.6±9.3% in the 300-mg group, vs. an increase of 4.2±41.7% in the placebo group) and when it was administered as an add-on to fibrates (decreases of 60.2±12.5% in the 200-mg group and 70.9±13.0% in the 300-mg group, vs. a decrease of 2.2±25.2% in the placebo group). Concordant reductions of 31.3 to 70.9% were observed in triglyceride levels. No safety concerns were identified in this short-term study. CONCLUSIONS: We found that treatment with ISIS 304801 was associated with significant lowering of triglyceride levels, among patients with a broad range of baseline levels, through selective antisense inhibition of APOC3 synthesis. (Funded by Isis Pharmaceuticals; ClinicalTrials.gov number, NCT01529424.).

Prevention of hepatic fibrosis with liver microsomal triglyceride transfer protein deletion in liver fatty acid binding protein null mice.

Blocking hepatic very low-density lipoprotein secretion through genetic or pharmacologic inhibition of microsomal triglyceride transfer protein (Mttp) causes hepatic steatosis, yet the risks for developing hepatic fibrosis are poorly understood. We report that liver-specific Mttp knockout mice (Mttp-LKO) exhibit both steatosis and fibrosis, which is exacerbated by a high-transfat/fructose diet. When crossed into germline liver fatty acid (FA) binding protein null mice (Mttp-LKO, i.e., double knockout mice) hepatic steatosis was greatly diminished and fibrosis prevented, on both low-fat and high-fat diets. The mechanisms underlying protection include reduced long chain FA uptake, shifts in FA distribution (lipidomic profiling), and metabolic turnover, specifically decreased hepatic 18:2 FA and triglyceride species and a shift in 18:2 FA use for oxidation versus incorporation into newly synthesized triglyceride. Double knockout mice were protected against fasting-induced hepatic steatosis (a model of enhanced exogenous FA delivery) yet developed steatosis upon induction of hepatic de novo lipogenesis with fructose feeding. Mttp-LKO mice, on either the liver FA binding protein null or Apobec-1 null background (i.e., apolipoprotein B100 only) exhibited only subtle increases in endoplasmic reticulum stress, suggesting that an altered unfolded protein response is unlikely to account for the attenuated phenotype in double knockout mice. Acute, antisense-mediated liver FA binding protein knockdown in Mttp-LKO mice also reduced FA uptake, increased oxidation versus incorporation of 18:2 species with complete reversal of hepatic steatosis, increased hepatic injury, and worsened fibrosis. CONCLUSION: Perturbing exogenous hepatic FA use modulates both hepatic steatosis and fibrosis in the setting of hepatic Mttp deletion, adding new insight into the pathophysiological mechanisms and consequences of defective very low-density lipoprotein secretion. (Hepatology 2017;65:836-852).

The lipid droplet-associated protein perilipin 3 facilitates hepatitis C virus-driven hepatic steatosis.

Hepatitis C virus (HCV) is an enveloped RNA virus responsible for 170 million cases of viral hepatitis worldwide. Over 50% of chronically infected HCV patients develop hepatic steatosis, and steatosis can be induced by expression of HCV core protein (core) alone. Additionally, core must associate with cytoplasmic lipid droplets (LDs) for steatosis development and viral particle assembly. Due to the importance of the LD as a key component of hepatic lipid storage and as a platform for HCV particle assembly, it seems this dynamic subcellular organelle is a gatekeeper in the pathogenesis of viral hepatitis. Here, we hypothesized that core requires the host LD scaffold protein, perilipin (PLIN)3, to induce hepatic steatosis. To test our hypothesis in vivo, we have studied core-induced hepatic steatosis in the absence or presence of antisense oligonucleotide-mediated knockdown of PLIN3. PLIN3 knockdown blunted HCV core-induced steatosis in transgenic mice fed either chow or a moderate fat diet. Collectively, our studies demonstrate that the LD scaffold protein, PLIN3, is essential for HCV core-induced hepatic steatosis and provide new insights into the pathogenesis of HCV.

Insulin Dissociates the Effects of Liver X Receptor on Lipogenesis, Endoplasmic Reticulum Stress, and Inflammation.

Diabetes is characterized by increased lipogenesis as well as increased endoplasmic reticulum (ER) stress and inflammation. The nuclear hormone receptor liver X receptor (LXR) is induced by insulin and is a key regulator of lipid metabolism. It promotes lipogenesis and cholesterol efflux, but suppresses endoplasmic reticulum stress and inflammation. The goal of these studies was to dissect the effects of insulin on LXR action. We used antisense oligonucleotides to knock down Lxrα in mice with hepatocyte-specific deletion of the insulin receptor and their controls. We found, surprisingly, that knock-out of the insulin receptor and knockdown of Lxrα produced equivalent, non-additive effects on the lipogenic genes. Thus, insulin was unable to induce the lipogenic genes in the absence of Lxrα, and LXRα was unable to induce the lipogenic genes in the absence of insulin. However, insulin was not required for LXRα to modulate the phospholipid profile, or to suppress genes in the ER stress or inflammation pathways. These data show that insulin is required specifically for the lipogenic effects of LXRα and that manipulation of the insulin signaling pathway could dissociate the beneficial effects of LXR on cholesterol efflux, inflammation, and ER stress from the negative effects on lipogenesis.

Antisense oligonucleotides targeting apolipoprotein(a) in people with raised lipoprotein(a): two randomised, double-blind, placebo-controlled, dose-ranging trials.

BACKGROUND: Elevated lipoprotein(a) (Lp[a]) is a highly prevalent (around 20% of people) genetic risk factor for cardiovascular disease and calcific aortic valve stenosis, but no approved specific therapy exists to substantially lower Lp(a) concentrations. We aimed to assess the efficacy, safety, and tolerability of two unique antisense oligonucleotides designed to lower Lp(a) concentrations. METHODS: We did two randomised, double-blind, placebo-controlled trials. In a phase 2 trial (done in 13 study centres in Canada, the Netherlands, Germany, Denmark, and the UK), we assessed the effect of IONIS-APO(a)Rx, an oligonucleotide targeting apolipoprotein(a). Participants with elevated Lp(a) concentrations (125-437 nmol/L in cohort A; ≥438 nmol/L in cohort B) were randomly assigned (in a 1:1 ratio in cohort A and in a 4:1 ratio in cohort B) with an interactive response system to escalating-dose subcutaneous IONIS-APO(a)Rx (100 mg, 200 mg, and then 300 mg, once a week for 4 weeks each) or injections of saline placebo, once a week, for 12 weeks. Primary endpoints were mean percentage change in fasting plasma Lp(a) concentration at day 85 or 99 in the per-protocol population (participants who received more than six doses of study drug) and safety and tolerability in the safety population. In a phase 1/2a first-in-man trial, we assessed the effect of IONIS-APO(a)-LRx, a ligand-conjugated antisense oligonucleotide designed to be highly and selectively taken up by hepatocytes, at the BioPharma Services phase 1 unit (Toronto, ON, Canada). Healthy volunteers (Lp[a] ≥75 nmol/L) were randomly assigned to receive a single dose of 10-120 mg IONIS-APO(a)LRx subcutaneously in an ascending-dose design or placebo (in a 3:1 ratio; single-ascending-dose phase), or multiple doses of 10 mg, 20 mg, or 40 mg IONIS-APO(a)LRx subcutaneously in an ascending-dose design or placebo (in an 8:2 ratio) at day 1, 3, 5, 8, 15, and 22 (multiple-ascending-dose phase). Primary endpoints were mean percentage change in fasting plasma Lp(a) concentration, safety, and tolerability at day 30 in the single-ascending-dose phase and day 36 in the multiple-ascending-dose phase in participants who were randomised and received at least one dose of study drug. In both trials, the randomised allocation sequence was generated by Ionis Biometrics or external vendor with a permuted-block randomisation method. Participants, investigators, sponsor personnel, and clinical research organisation staff who analysed the data were all masked to the treatment assignments. Both trials are registered with ClinicalTrials.gov, numbers NCT02160899 and NCT02414594. FINDINGS: From June 25, 2014, to Nov 18, 2015, we enrolled 64 participants to the phase 2 trial (51 in cohort A and 13 in cohort B). 35 were randomly assigned to IONIS-APO(a)Rx and 29 to placebo. At day 85/99, participants assigned to IONIS-APO(a)Rx had mean Lp(a) reductions of 66·8% (SD 20·6) in cohort A and 71·6% (13·0) in cohort B (both p<0·0001 vs pooled placebo). From April 15, 2015, to Jan 11, 2016, we enrolled 58 healthy volunteers to the phase 1/2a trial of IONIS-APO(a)-LRx. Of 28 participants in the single-ascending-dose phase, three were randomly assigned to 10 mg, three to 20 mg, three to 40 mg, six to 80 mg, six to 120 mg, and seven to placebo. Of 30 participants in the multiple-ascending-dose phase, eight were randomly assigned to 10 mg, eight to 20 mg, eight to 40 mg, and six to placebo. Significant dose-dependent reductions in mean Lp(a) concentrations were noted in all single-dose IONIS-APO(a)-LRx groups at day 30. In the multidose groups, IONIS-APO(a)-LRx resulted in mean reductions in Lp(a) of 66% (SD 21·8) in the 10 mg group, 80% (SD 13·7%) in the 20 mg group, and 92% (6·5) in the 40 mg group (p=0·0007 for all vs placebo) at day 36. Both antisense oligonucleotides were safe. There were two serious adverse events (myocardial infarctions) in the IONIS-APO(a)Rx phase 2 trial, one in the IONIS-APO(a)Rx and one in the placebo group, but neither were thought to be treatment related. 12% of injections with IONIS-APO(a)Rx were associated with injection-site reactions. IONIS-APO(a)-LRx was associated with no injection-site reactions. INTERPRETATION: IONIS-APO(a)-LRx is a novel, tolerable, potent therapy to reduce Lp(a) concentrations. IONIS-APO(a)-LRx might mitigate Lp(a)-mediated cardiovascular risk and is being developed for patients with elevated Lp(a) concentrations with existing cardiovascular disease or calcific aortic valve stenosis. FUNDING: Ionis Pharmaceuticals.

Targeting APOC3 in the familial chylomicronemia syndrome.

The familial chylomicronemia syndrome is a genetic disorder characterized by severe hypertriglyceridemia and recurrent pancreatitis due to a deficiency in lipoprotein lipase (LPL). Currently, there are no effective therapies except for extreme restriction in the consumption of dietary fat. Apolipoprotein C-III (APOC3) is known to inhibit LPL, although there is also evidence that APOC3 increases the level of plasma triglycerides through an LPL-independent mechanism. We administered an inhibitor of APOC3 messenger RNA (mRNA), called ISIS 304801, to treat three patients with the familial chylomicronemia syndrome and triglyceride levels ranging from 1406 to 2083 mg per deciliter (15.9 to 23.5 mmol per liter). After 13 weeks of study-drug administration, plasma APOC3 levels were reduced by 71 to 90% and triglyceride levels by 56 to 86%. During the study, all patients had a triglyceride level of less than 500 mg per deciliter (5.7 mmol per liter) with treatment. These data support the role of APOC3 as a key regulator of LPL-independent pathways of triglyceride metabolism.

Type 1 Deiodinase Regulates ApoA-I Gene Expression and ApoA-I Synthesis Independent of Thyroid Hormone Signaling.

OBJECTIVE: Plasma levels of high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (ApoA-I) are reduced in individuals with defective insulin signaling. Initial studies using liver-specific insulin receptor (InsR) knockout mice identified reduced expression of type 1 deiodinase (Dio1) as a potentially novel link between defective hepatic insulin signaling and reduced expression of the ApoA-I gene. Our objective was to examine the regulation of ApoA-I expression by Dio1. APPROACH AND RESULTS: Acute inactivation of InsR by adenoviral delivery of Cre recombinase to InsR floxed mice reduced HDL-C and expression of both ApoA-I and Dio1. Overexpression of Dio1 in InsR knockout mice restored HDL-C and ApoA-I levels and increased the expression of ApoA-I. Dio1 knockout mice had low expression of ApoA-I and reduced serum levels of HDL-C and ApoA-I. Treatment of C57BL/6J mice with antisense to Dio1 reduced ApoA-I mRNA, HDL-C, and serum ApoA-I. Hepatic 3,5,3'-triiodothyronine content was normal or elevated in InsR knockout mice or Dio1 knockout mice. Knockdown of either InsR or Dio1 by siRNA in HepG2 cells decreased the expression of ApoA-I and ApoA-I synthesis and secretion. siRNA knockdown of InsR or Dio1 decreased activity of a region of the ApoA-I promoter lacking thyroid hormone response elements (region B). Electrophoretic mobility shift assay demonstrated that reduced Dio1 expression decreased the binding of nuclear proteins to region B. CONCLUSIONS: Reductions in Dio1 expression reduce the expression of ApoA-I in a 3,5,3'-triiodothyronine-/thyroid hormone response element-independent manner.

Hypercholesterolemia Induced by a PCSK9 Gain-of-Function Mutation Augments Angiotensin II-Induced Abdominal Aortic Aneurysms in C57BL/6 Mice-Brief Report.

OBJECTIVE: Gain-of-function mutations of PCSK9 (proprotein convertase subtilisin/kexin type 9) lead to hypercholesterolemia. This study was to determine whether infection of normocholesterolemic mice with an adeno-associated viral (AAV) vector expressing a gain-of-function mutation of mouse PCSK9 increased angiotensin II (AngII)-induced abdominal aortic aneurysms. APPROACH AND RESULTS: In an initial study, male C57BL/6 mice were injected intraperitoneally with either an empty vector or PCSK9 gain-of-function mutation (D377Y). AAV at 3 doses and fed a saturated fat-enriched diet for 6 weeks. Two weeks after AAV injection, mice were infused with AngII for 4 weeks. Plasma PCSK9 concentrations were increased dose dependently in mice injected with AAV containing PCSK9D377Y mutation and positively associated with elevations of plasma cholesterol concentrations. Infection with intermediate and high doses of PCSK9D377Y.AAV led to equivalent increases of maximal width of abdominal aortas in C57BL/6 mice infused with AngII. Therefore, the intermediate dose was used in subsequent experiments. We then determined effects of PCSK9D377Y.AAV infection on 5 normolipidemic mouse strains, demonstrating that C57BL/6 mice were the most susceptible to this AAV infection. PCSK9D377Y.AAV infected male C57BL/6 mice were also compared with age-matched male low-density lipoprotein receptor(-/-) mice. Although plasma cholesterol concentrations were lower in mice infected with PCSK9D377Y.AAV, these mice had equivalent abdominal aortic aneurysmal formation, compared to low-density lipoprotein receptor(-/-) mice. In a separate study, reduced plasma PCSK9 concentrations by PCSK9 antisense oligonucleotides in male low-density lipoprotein receptor(-/-) mice did not influence AngII-induced abdominal aortic aneurysms. CONCLUSION: AAV-mediated infection with a mouse PCSK9 gain-of-function mutation is a rapid, easy, and efficient approach for inducing hypercholesterolemia and promoting abdominal aortic aneurysms in C57BL/6 mice infused with AngII.

Angiotensinogen Exerts Effects Independent of Angiotensin II.

OBJECTIVE: This study determined whether angiotensinogen (AGT) has angiotensin II-independent effects using multiple genetic and pharmacological manipulations. APPROACH AND RESULTS: All study mice were in low-density lipoprotein receptor -/- background and fed a saturated fat-enriched diet. In mice with floxed alleles and a neomycin cassette in intron 2 of the AGT gene (hypoAGT mice), plasma AGT concentrations were >90% lower compared with their wild-type littermates. HypoAGT mice had lower systolic blood pressure, less atherosclerosis, and diminished body weight gain and liver steatosis. Low plasma AGT concentrations and all phenotypes were recapitulated in mice with hepatocyte-specific deficiency of AGT or pharmacological inhibition of AGT by antisense oligonucleotide administration. In contrast, inhibition of AGT cleavage by a renin inhibitor, aliskiren, failed to alter body weight gain and liver steatosis in low-density lipoprotein receptor -/- mice. In mice with established adiposity, administration of AGT antisense oligonucleotide versus aliskiren led to equivalent reductions of systolic blood pressure and atherosclerosis. AGT antisense oligonucleotide administration ceased body weight gain and further reduced body weight, whereas aliskiren did not affect body weight gain during continuous saturated fat-enriched diet feeding. Structural comparisons of AGT proteins in zebrafish, mouse, rat, and human revealed 4 highly conserved sequences within the des(angiotensin I)AGT domain. des(angiotensin I)AGT, through adeno-associated viral infection in hepatocyte-specific AGT-deficient mice, increased body weight gain and liver steatosis, but did not affect atherosclerosis. CONCLUSIONS: AGT contributes to body weight gain and liver steatosis through functions of the des(angiotensin I)AGT domain, which are independent of angiotensin II production.