Faculty Bibliography

Understanding the molecular defects underlying cardiovascular disease is necessary for the development of therapeutics. The most common method to lower circulating lipids, which reduces the incidence of cardiovascular disease, is statins, but other drugs are now entering the clinic, some of which have been approved. Nevertheless, patients cannot tolerate some of these therapeutics, the drugs are costly, or the treatments are approved for only rare forms of disease. Efforts to find alternative treatments have focused on other factors, such as apolipoproteinB (apoB), which transports cholesterol in the blood stream. The levels of apoB are regulated by endoplasmic reticulum (ER) associated degradation as well as by a post ER degradation pathway in model systems, and we suggest that these events provide novel therapeutic targets. We discuss first how cardiovascular disease arises and how cholesterol is regulated, and then summarize the mechanisms of action of existing treatments for cardiovascular disease. We then review the apoB biosynthetic pathway, focusing on steps that might be amenable to therapeutic interventions.

Macrophage accumulation in atherosclerosis is directly linked to the destabilization and rupture of plaque, causing acute atherothrombotic events. Circulating monocytes enter the plaque and differentiate into macrophages, where they are activated by CD4⁺ T lymphocytes through CD40-CD40 ligand signalling. Here, we report the development and multiparametric evaluation of a nanoimmunotherapy that moderates CD40-CD40 ligand signalling in monocytes and macrophages by blocking the interaction between CD40 and tumour necrosis factor receptor-associated factor 6 (TRAF6). We evaluated the biodistribution characteristics of the nanoimmunotherapy in apolipoprotein E-deficient (Apoe^-/-) mice and in non-human primates by in vivo positron-emission tomography imaging. In Apoe^-/- mice, a 1-week nanoimmunotherapy treatment regimen achieved significant anti-inflammatory effects, which was due to the impaired migration capacity of monocytes, as established by a transcriptome analysis. The rapid reduction of plaque inflammation by the TRAF6-targeted nanoimmunotherapy and its favourable toxicity profiles in both mice and non-human primates highlights the translational potential of this strategy for the treatment of atherosclerosis.

OBJECTIVE:Statin intolerance, whether real or perceived, is a growing issue in clinical practice. Our aim was to evaluate the effects of reduced-dose statin therapy complemented with nutraceuticals. METHODS:First phase: Initially, 53 type 2 diabetic statin-treated patients received a supplementation with fish oil (1.7 g EPA + DHA/day), chocolate containing plant sterols (2.2 g/day), and green tea (two sachets/day) for 6 weeks. Second phase: "Good responders" to supplementation were identified after multivariate analysis (n = 10), and recruited for a pilot protocol of statin dose reduction. "Good responders" were then provided with supplementation for 12 weeks: standard statin therapy was kept during the first 6 weeks and reduced by 50% from weeks 6-12. RESULTS:First phase: After 6 weeks of supplementation, plasma LDL-C (-13.7% ± 3.7, P = .002) and C-reactive protein (-35.5% ± 5.9, P = .03) were reduced. Analysis of lathosterol and campesterol in plasma suggested that intensity of LDL-C reduction was influenced by cholesterol absorption rate rather than its synthesis. Second phase: no difference was observed for plasma lipids, inflammation, cholesterol efflux capacity, or HDL particles after statin dose reduction when compared to standard therapy. CONCLUSIONS:Although limited by the small sample size, our study demonstrates the potential for a new therapeutic approach combining lower statin dose and specific dietary compounds. Further studies should elucidate "good responders" profile as a tool for personalized medicine. This may be particularly helpful in the many patients with or at risk for CVD who cannot tolerate high dose statin therapy. TRIAL REGISTRATION/BACKGROUND:ClinicalTrials.gov, NCT02732223.

BACKGROUND:Patients undergoing cardiovascular (CV) procedures often have suboptimal CV risk factor control and may benefit from strategies targeting healthy lifestyle behaviors and education. Implementation of prevention strategies may be particularly effective at this point of heightened motivation. METHODS:A prospective, randomized, pilot study was conducted in 400 patients undergoing a nonurgent CV procedure (cardiac catheterization ± revascularization) to evaluate the impact of different prevention strategies. Patients were randomized in a 1:1:1 fashion to usual care (UC; group A, n = 134), in-hospital CV prevention consult (PC; group B, n = 130), or PC plus behavioral intervention program (telephone-based motivational interviewing and optional tailored text messages) (group C, n = 133). The primary end point was the Δ change in non-high-density lipoprotein cholesterol (non-HDL-C) from baseline to 6 month. RESULTS:The mean age was 64.6 ± 10.8 years, 23.7% were female, and 31.5% were nonwhite. After 6 months, the absolute difference in non-HDL-C for all participants was -19.8 mg/dL (95% CI -24.1 to -15.6, P < .001). There were no between-group differences in the primary end point for the combined PC groups (B and C) versus UC, with a Δ adjusted between group difference of -5.5 mg/dL (95% CI -13.1 to 2.1, P = .16). Patients in the PC groups were more likely to be on high-intensity statins at 6 months (52.9% vs 38.1%, P = .01). After excluding participants with baseline non-HDL-C <100 mg/dL (initial exclusion criterion), Δ non-HDL-C and Δ low-density lipoprotein cholesterol were improved in the PC groups compared to UC (non-HDL-C -8.13 mg/dL [-16.00 to -0.27], P = .04; low-density lipoprotein cholesterol -7.87mg/dL [-15.10 to -0.64], P = .03). CONCLUSIONS:Although non-HDL-C reduction at 6 months following a nonurgent CV procedure was not significant in the overall cohort, an increased uptake in high-potency statins may translate into improved long-term health outcomes and cost reductions.

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/or methods that block liver lipoprotein secretion. Objective: We sought to develop a more direct and time-effective method to create and then reverse hypercholesterolemia as well as atherosclerosis via transient knockdown of the hepatic LDL receptor (LDLR) 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 due to recovery of hepatic LDLR expression. This led to a decrease in macrophages within the aortic root plaques and brachiocephalic artery, i.e. regression of inflammatory cell content, after a period of 2-3 weeks. Conclusions: We have developed an inducible and reversible hepatic LDLR knockdown mouse model of atherosclerosis regression. While 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.

Rationale: Genome-Wide Association Studies identified single nucleotide polymorphisms (SNPs) near the SORT1 locus strongly associated with decreased plasma low-density lipoprotein cholesterol (LDL-C) levels and protection from atherosclerotic cardiovascular disease and myocardial infarction. The minor allele of the causal SORT1 SNP locus creates a putative C/EBPα binding site in the SORT1 promoter, thereby increasing sortilin expression by 12-fold in liver, which is rich in this transcription factor. Our previous studies in mice have showed reductions in plasma LDL-C and its principal protein component, apolipoprotein B (apoB) with increased SORT1 expression, and in vitro studies suggested that sortilin promoted the presecretory lysosomal degradation of apoB associated with the LDL precursor, very-low density lipoprotein (VLDL). Objective: To determine directly that SORT1 overexpression results in apoB degradation and to identify the mechanisms by which this reduces apoB and VLDL secretion by the liver, thereby contributing to understanding the clinical phenotype of lower LDL-C levels. Methods and Results: Pulse-chase studies directly established that SORT1 overexpression results in apoB degradation. As noted above, previous work implicated a role for lysosomes in this degradation. Through in vitro and in vivo studies, we now demonstrate that the sortilin-mediated route of apoB to lysosomes is unconventional and intersects with autophagy. Increased expression of sortilin diverts more apoB away from secretion, with both proteins trafficking to the endosomal compartment in vesicles that fuse with autophagosomes to form amphisomes. The amphisomes then merge with lysosomes. Furthermore, we show that sortilin itself is a regulator of autophagy and that its activity is scaled to the level of apoB synthesis. Conclusions: These results strongly suggest that an unconventional lysosomal targeting process dependent on autophagy degrades apoB that was diverted from the secretory pathway by sortilin, and provide a mechanism contributing to the reduced LDL-C found in individuals with SORT1 overexpression.

BACKGROUND:Disrupting the costimulatory CD40-CD40L dyad reduces atherosclerosis, but can result in immune suppression. The authors recently identified small molecule inhibitors that block the interaction between CD40 and tumor necrosis factor receptor-associated factor (TRAF) 6 (TRAF-STOPs), while leaving CD40-TRAF2/3/5 interactions intact, thereby preserving CD40-mediated immunity. OBJECTIVES/OBJECTIVE:This study evaluates the potential of TRAF-STOP treatment in atherosclerosis. METHODS:The effects of TRAF-STOPs on atherosclerosis were investigated in apolipoprotein E deficient (Apoe-/-) mice. Recombinant high-density lipoprotein (rHDL) nanoparticles were used to target TRAF-STOPs to macrophages. RESULTS:TRAF-STOP treatment of young Apoe-/- mice reduced atherosclerosis by reducing CD40 and integrin expression in classical monocytes, thereby hampering monocyte recruitment. When Apoe-/- mice with established atherosclerosis were treated with TRAF-STOPs, plaque progression was halted, and plaques contained an increase in collagen, developed small necrotic cores, and contained only a few immune cells. TRAF-STOP treatment did not impair "classical" immune pathways of CD40, including T-cell proliferation and costimulation, Ig isotype switching, or germinal center formation, but reduced CD40 and β2-integrin expression in inflammatory monocytes. In vitro testing and transcriptional profiling showed that TRAF-STOPs are effective in reducing macrophage migration and activation, which could be attributed to reduced phosphorylation of signaling intermediates of the canonical NF-κB pathway. To target TRAF-STOPs specifically to macrophages, TRAF-STOP 6877002 was incorporated into rHDL nanoparticles. Six weeks of rHDL-6877002 treatment attenuated the initiation of atherosclerosis in Apoe-/- mice. CONCLUSIONS:TRAF-STOPs can overcome the current limitations of long-term CD40 inhibition in atherosclerosis and have the potential to become a future therapeutic for atherosclerosis.