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Oxidized phospholipids (OxPL) are ubiquitous, are formed in many inflammatory tissues, including atherosclerotic lesions, and frequently mediate proinflammatory changes 1 . Because OxPL are mostly the products of non-enzymatic lipid peroxidation, mechanisms to specifically neutralize them are unavailable and their roles in vivo are largely unknown. We previously cloned the IgM natural antibody E06, which binds to the phosphocholine headgroup of OxPL, and blocks the uptake of oxidized low-density lipoprotein (OxLDL) by macrophages and inhibits the proinflammatory properties of OxPL 2 – 4 . Here, to determine the role of OxPL in vivo in the context of atherogenesis, we generated transgenic mice in the Ldlr −/− background that expressed a single-chain variable fragment of E06 (E06-scFv) using the Apoe promoter. E06-scFv was secreted into the plasma from the liver and macrophages, and achieved sufficient plasma levels to inhibit in vivo macrophage uptake of OxLDL and to prevent OxPL-induced inflammatory signalling. Compared to Ldlr −/− mice, Ldlr −/− E06-scFv mice had 57–28% less atherosclerosis after 4, 7 and even 12 months of 1% high-cholesterol diet. Echocardiographic and histologic evaluation of the aortic valves demonstrated that E06-scFv ameliorated the development of aortic valve gradients and decreased aortic valve calcification. Both cholesterol accumulation and in vivo uptake of OxLDL were decreased in peritoneal macrophages, and both peritoneal and aortic macrophages had a decreased inflammatory phenotype. Serum amyloid A was decreased by 32%, indicating decreased systemic inflammation, and hepatic steatosis and inflammation were also decreased. Finally, the E06-scFv prolonged life as measured over 15 months. Because the E06-scFv lacks the functional effects of an intact antibody other than the ability to bind OxPL and inhibit OxLDL uptake in macrophages, these data support a major proatherogenic role of OxLDL and demonstrate that OxPL are proinflammatory and proatherogenic, which E06 counteracts in vivo. These studies suggest that therapies inactivating OxPL may be beneficial for reducing generalized inflammation, including the progression of atherosclerosis, aortic stenosis and hepatic steatosis. A single-chain variable fragment of the antibody E06, which binds to the phosphocholine headgroup of oxidized phospholipids, blocks the uptake of oxidized low-density lipoprotein by macrophages, and reduces inflammation and atherosclerosis in hypercholesterolaemic mice.

Regulation of gene expression requires the combinatorial binding of sequence-specific transcription factors (TFs) at promoters and enhancers. Prior studies showed that alterations in the spacing between TF binding sites can influence promoter and enhancer activity. However, the relative importance of TF spacing alterations resulting from naturally occurring insertions and deletions (InDels) has not been systematically analyzed. To address this question, we first characterized the genome-wide spacing relationships of 73 TFs in human K562 cells as determined by ChIP-seq (chromatin immunoprecipitation sequencing). We found a dominant pattern of a relaxed range of spacing between collaborative factors, including 45 TFs exclusively exhibiting relaxed spacing with their binding partners. Next, we exploited millions of InDels provided by genetically diverse mouse strains and human individuals to investigate the effects of altered spacing on TF binding and local histone acetylation. These analyses suggested that spacing alterations resulting from naturally occurring InDels are generally tolerated in comparison to genetic variants directly affecting TF binding sites. To experimentally validate this prediction, we introduced synthetic spacing alterations between PU.1 and C/EBPβ binding sites at six endogenous genomic loci in a macrophage cell line. Remarkably, collaborative binding of PU.1 and C/EBPβ at these locations tolerated changes in spacing ranging from 5 bp increase to >30 bp decrease. Collectively, these findings have implications for understanding mechanisms underlying enhancer selection and for the interpretation of non-coding genetic variation.

The results of this phase 3 trial of the effect of olezarsen, a drug that targets APOC3 mRNA, on plasma triglyceride levels and acute pancreatitis in familial chylomicronemia syndrome support further clinical research.

In a phase 2b trial involving patients with hypertriglyceridemia, the use of olezarsen (which targets APOC3 mRNA) for 6 months reduced triglyceride levels by approximately 50% as compared with placebo.

Hypertriglyceridemia and Risk of PancreatitisThis meta-analysis of three clinical trials assessed the effect of triglyceride-lowering pharmacologic therapy on the risk of acute pancreatitis in patients with severe hypertriglyceridemia.

The serine protease inhibitor protein C inhibitor (PCI) is expressed in many human tissues and exhibits broad protease reactivity. PCI binds glycosaminoglycans and certain phospholipids, which modulate its inhibitory activity. Enteropeptidase (EP) is a type II transmembrane serine protease mainly found on the brush border membrane of epithelial cells in the duodenum, where it activates trypsinogen to initiate the digestion of food proteins. Some active EP is also present in duodenal fluid and has been made responsible for causing pancreatitis in case of duodeno-pancreatic reflux. Together with its substrate trypsinogen, EP is furthermore present in the epidermis and in some cancer cells. In this report, we show that PCI inhibited EP with an apparent 2nd order rate constant of 4.48 × 10(4) M(-1) s(-1). Low molecular weight (LMWH) and unfractionated heparin (UFH) slightly reduced the inhibitory effect of PCI. The SI (stoichiometry of inhibition) value for the inhibition of EP by PCI was 10.8 in the absence and 17.9 in the presence of UFH (10 U/ml). By inhibiting trypsin, chymotrypsin, and additionally EP, PCI might play a role in the protection of the pancreas from autodigestion. Furthermore the interaction of PCI with EP may influence the regulation of epithelial differentiation.

Elevated triglycerides are an important risk factor for atherosclerosis. However, the magnitude of triglyceride lowering with currently available therapies is modest and the impact of triglyceride-lowering on atherosclerosis remains undefined. Olezarsen is an antisense oligonucleotide (ASO) targeting mRNA for apolipoprotein C-III (apoC-III), an inhibitor of triglyceride clearance. The Essence–TIMI 73b trial (NCT05610280) is a randomized, double-blind, placebo-controlled phase 3 trial of olezarsen 50 mg or 80 mg every 4 weeks compared with placebo. The trial enrolled adults with either moderate hypertriglyceridemia (200-499 mg/dL) plus increased cardiovascular risk, or severe hypertriglyceridemia (≥500 mg/dL). The primary endpoint is the percent change in triglyceride levels from baseline to 6 months, reported as the difference between each olezarsen dose group and pooled placebo. A coronary computed tomography angiography (CTA) substudy will examine changes in noncalcified plaque volume from baseline to 12 months. A total of 1,478 patients were randomized at 160 sites in North America and Europe. The median age is 63 (IQR 56-69) years, 39% are women, and 71% are non-Hispanic White. Overall, 60% of patients have diabetes, and 42% have atherosclerotic cardiovascular disease. At randomization, 97% were receiving lipid-lowering therapies, including 82% on a statin. The median baseline triglyceride level was 249 (195-339) mg/dL and 9% of patients had triglycerides ≥500 mg/dL at enrollment. Approximately 1000 patients completed a baseline CTA, of whom 555 (55%) had measurable noncalcified coronary plaque and continued in the substudy. Targeting apoC-III to facilitate clearance of triglyceride-rich lipoproteins is a potential therapeutic strategy for lowering triglyceride levels, regressing atherosclerosis, and reducing cardiovascular risk. The phase 3 Essence–TIMI 73b trial, which has enrolled nearly 1,500 patients, including over 550 in a coronary CTA substudy, should provide key insights into the efficacy and safety of olezarsen in patients with largely moderate hypertriglyceridemia and elevated cardiovascular risk. Clinicaltrials.gov: NCT05610280

Severe hypertriglyceridemia (HTG), defined as a serum triglyceride (TG) concentration ≥500 mg/dl, is present in approximately 1 in every 100 individuals and carries direct clinical consequences, including pancreatitis, which can be life-threatening. Olezarsen is an investigational antisense oligonucleotide targeted to the mRNA for apolipoprotein C-III (apoC-III), a protein known to impair TG clearance by inhibiting lipoprotein lipase and the hepatic uptake of triglyceride-rich remnants. No dedicated trial has tested olezarsen in patients with severe HTG. In these 2 pivotal phase 3 trials, CORE-TIMI 72a and CORE2-TIMI 72b, patients with severe HTG were randomized in a 2:1 fashion to either olezarsen (80 mg or 50 mg dose) or matching placebo. Patients will be treated for a total of 12 months and evaluated for the primary endpoint of percent change in TGs from baseline to 6 months compared with placebo. Pooled analyses of CORE and CORE2 will also assess olezarsen's effect on acute pancreatitis events and change in hepatic steatosis. A total of 617 subjects in CORE-TIMI 72a and 446 subjects in CORE2-TIMI 72b were randomized. In these 2 trials, the median age was 54 and 55 years, women made up 24% and 23% of the study population, and the baseline TGs were 836 mg/dl and 749 mg/dl, respectively. A total of 333 subjects, 129 from CORE-TIMI 72a and 204 from CORE2-TIMI 72b, were enrolled in the hepatic MRI substudy. Together, CORE-TIMI 72a and CORE2-TIMI 72b are designed to establish the efficacy and safety of olezarsen in patients with severe HTG. Clinicaltrials.gov: NCT05079919 and NCT05552326.

In this Letter, affiliation number 1 was originally missing from the HTML; the affiliations were missing for author Ming-Yow Hung in the HTML; and the Fig. 4 legend erroneously referred to panels a – h , instead of a – g . These errors have been corrected online.

Abstract Disclosure: E.S. Stroes: Advisory Board Member; Self; Amgen Inc, Sanofi, Novartis Pharmaceuticals, AstraZeneca, Novo Nordisk, Ionis Pharmaceuticals Inc., Merck, Daiichi Sankyo. Grant Recipient; Self; Ionis Pharmaceuticals Inc., Novo Nordisk, Novartis Pharmaceuticals, Sanofi. V. Alexander: Employee; Self; Ionis Pharmaceuticals Inc. E. Prokopczuk: Employee; Self; Ionis Pharmaceuticals Inc. R.A. Hegele: Consulting Fee; Self; Aegerion Pharmaceuticals, Ionis Pharmaceuticals Inc., Amgen Inc, Novartis Pharmaceuticals, Pfizer, Inc., Regeneron Pharmaceuticals, Sanofi, Ultragenyx, Acasti, and HLS Therapeutics. M. Arca: Grant Recipient; Self; Amgen Inc, Ionis Pharmaceuticals Inc., Novartis Pharmaceuticals, Pfizer, Inc., Regeneron Pharmaceuticals, Sanofi, Ultragenyx, Daiichi Sankyo, Alfasigma, Amryt, Sobi, and Viatris. C.M. Ballantyne: Consulting Fee; Self; 89Bio, Abbott Diagnostics, Alnylam Pharmaceuticals, Althera, Amarin, Amgen, Arrowhead, AstraZeneca, Denka Seiken, Esperion, Genentech, Gilead, Illumina, Ionis, Matinas BioPharma Inc, Merck, New Amster. Grant Recipient; Self; Abbott Diagnostic, Akcea, Amgen, Arrowhead, Esperion, Ionis, Merck, Novartis, Novo Nordisk, Regeneron, Roche Diagnostic, NIH, AHA, ADA. H. Soran: Grant Recipient; Self; Akcea Therapeutics, Alexion, Amryt, Kowa, MSD, NAPP, Novartis, Pfizer, Sanofi, Synageva, and Takeda. T.A. Prohaska: Employee; Self; Ionis Pharmaceuticals Inc. S. Xia: Employee; Self; Ionis Pharmaceuticals Inc. H.N. Ginsberg: Research Investigator; Self; Ionis Pharmaceuticals Inc. J.L. Witztum: Consulting Fee; Self; Ionis Pharmaceuticals Inc. S. Tsimikas: Consulting Fee; Self; Novartis. Employee; Self; Ionis Pharmaceuticals Inc.. Stock Owner; Self; Kleanathi, Oxitope. Background: Familial chylomicronemia syndrome (FCS) is a rare genetic disorder of lipoprotein lipase deficiency that results in severe hypertriglyceridemia and an increased risk of potentially life-threatening acute pancreatitis (AP). Decreasing high plasma levels of apolipoprotein C-III (apoC-III) reduces hypertriglyceridemia. Olezarsen is an investigational ligand-conjugated antisense oligonucleotide targeted to hepatic APOC3 mRNA to reduce triglycerides (TG). Methods: Balance is a Phase 3, multicenter, randomized, double-blind, placebo-controlled trial in 66 patients with genetically confirmed FCS and fasting TG ≥880 mg/dL at screening. Patients were advised to consume <20g fat/day and randomized 2:1 to olezarsen (50 mg or 80 mg) or placebo sc every 4 weeks for 53 weeks. The two primary endpoints were the placebo-adjusted % change in fasting TG from baseline to 6-months for (1) olezarsen 80 mg and (2) olezarsen 50 mg. Secondary endpoints included change in 12-month TG and apoC-III levels, and incidence of independently adjudicated AP events. Results: At baseline, TG levels were ∼2600 mg/dL and 47/66 (71%) of FCS patients had a history of AP. Placebo-corrected TG levels at 6 months were significantly reduced in olezarsen 80 mg (-43.5%, P=0.0009), and were numerically lower in the olezarsen 50 mg group (-22.4%, P=0.0775). Placebo-corrected TG levels at 12 months were reduced -59.4% in the olezarsen 80 mg group and -43.8% in the olezarsen 50 mg group. ApoC-III levels were reduced in both dose groups at 6 months (olezarsen 50 mg: -65.5%; olezarsen 80 mg: -73.7%) and 12 months (olezarsen 50 mg: -77.1%; olezarsen 80 mg: -81.3%). During 53 weeks of randomized treatment, 11 episodes of AP were observed in 23 patients on placebo versus 2 episodes in 43 olezarsen-treated patients (1 in 50 mg and 1 in 80 mg group). A favorable safety and tolerability profile was noted with more treatment emergent adverse events (TEAEs) and serious TEAEs in the placebo group. No serious TEAEs were related to study drug. Conclusion: In patients with FCS, olezarsen 80 mg significantly reduced TG levels and both olezarsen 50 and 80 mg groups demonstrated a marked reduction in AP events with a favorable safety and tolerability profile. Presentation: 6/1/2024