Target For Treatment Of Dyslipidemia Research Articles

Bempedoic acid, an ATP citrate lyase inhibitor, reduces intimal hyperplasia via activation of AMPKα signaling pathway.

One of the common pathophysiological basis of atherosclerosis is intimal hyperplasia. ATP citrate lyase (ACLY) has been reported as a promising therapeutic target for treatment of dyslipidemia and atherosclerosis. However, the role of ACLY in intimal hyperplasia has yet to be clarified. The current investigation studies the molecular effects of ACLY and bempedoic acid, an ACLY inhibitor, on platelet-derived growth factor (PDGF)-induced primary human aortic smooth muscle cells (HASMCs) proliferation in vitro and on femoral arterial wire-injured neointimal hyperplasia in mouse in vivo. The role of ACLY in intimal hyperplasia was further investigated in mice treated with bempedoic acid. Cell proliferation was measured by CCK8 and BrdU assays. We explored further mechanisms using western blot, qPCR and immunofluorescence. We found that ACLY was significantly increased in dedifferentiated VSMC in vitro and vivo. Bempedoic acid which can inhibit ACLY expression effectively blocked PDGF-induced VSMC proliferation and dedifferentiation by activating AMPK/ACC signaling pathway. Moreover, bempedoic acid also attenuated VSMC proliferation and inhibited VSMC dedifferentiation in the wire-injured mouse femoral arteries, resulting in reduced neointima formation. We demonstrates that bempedoic acid reduces ACLY expression to restrain VSMC proliferation and dedifferentiation by activating AMPK/ACC signaling pathway, which may provide a potential therapeutic strategy for diseases associated with intimal hyperplasia including restenosis and atherosclerosis.

579-P: Dyslipidemia in Type 2 Diabetic Mice Is Improved by Targeting Smad3 with a Smad3 Inhibitor SIS3

Purpose of the Study: Dyslipidemia is one of the diabetic complications which is relevant to the disorder of interaction between glucose and lipid metabolism. In our preliminary studies, we found that Smad3 is the key pathogenic mediator in db/db mice. Metabolic symptoms in diabetes are improved in Smad3KO-db/db mice. Thus, we hypothesized that Smad3 is a therapeutic target for treatment of dyslipidemia in type 2 diabetes. Methods: db/db mice were treated with Smad3 inhibitor SIS3 at the age of 4 weeks at the dose of 2.5mg/kg bw/day by intra peritoneal injection for 8 weeks. Control group db/db mice were treated with SIS3 solvent only. Molecules and cytokines involved in lipid metabolism were examined by Realtime-PCR, Western blotting, immunohistochemistry, ELISA for in vivo and in vitro experiments. The mechanism of Smad3 signaling interfering lipid metabolism was studied by Chip-sequencing and RNA sequencing. Summary of the results: Blood high density lipoprotein (HDL) level was up regulated while low density lipoprotein (LDL) level and triglycerides were down regulated in Smad3 KO mice, which showed Smad3 is one of the main regulators in lipid metabolism. SIS3 treated mice showed significantly improved glycemia, lipidemia. Insulin sensitivity was ameliorated in SIS3 treatment group compared with control group. SIS3 treated Hepg2 cells and AML12 cells showed lower lipid absorbance than control group. RNA sequencing revealed that differentially expressed genes (DEGs) in concentrations of apolipoproteins A1 (ApoA1) was notable enriched in liver of Smad3KO mice, which also showed APOA1 has direct binding site with Smad3. We subsequently found that APOA1 was negatively regulated by Smad3 signaling therefore influence the lipid metabolism in type 2 diabetes. Conclusion: Smad3 is a pathogenic mediator of diabetic metabolism. Treatment of type 2 diabetic mice with Smad3 inhibitor SIS3 improves lipidemia by enhancing the activity of DEGs in APOA1. Disclosure H. He: None. X. Huang: None. R.C. Ma: Advisory Panel; Self; AstraZeneca. Stock/Shareholder; Self; GemVCare. Other Relationship; Self; AstraZeneca, Bayer Healthcare Pharmaceuticals Inc., Merck & Co., Inc., Novo Nordisk A/S, Pfizer Inc., Sanofi-Aventis, Tricida Inc. H. Lan: None.

Correction to: 2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association.

Correction to: 2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association.

Developments in intestinal cholesterol transport and triglyceride absorption.

To discuss recent advances in research focused on intestinal lipid handling. An important strategy in reducing atherosclerosis and risk of cardiovascular events is to increase the rate of reverse cholesterol transport, including its final step; cholesterol excretion from the body. The rate of removal is determined by a complex interplay between the factors involved in regulation of intestinal cholesterol absorption. One of these factors is a process known as transintestinal cholesterol excretion. This pathway comprises transport of cholesterol directly from the blood, through the enterocyte, into the intestinal lumen. In humans, this pathway accounts for 35% of cholesterol excretion in the feces. Mechanistic studies in mice revealed that, activation of the bile acid receptor farnesoid X receptor increases cholesterol removal via the transintestinal cholesterol excretion pathway as well as decreases plasma cholesterol and triglyceride providing an interesting target for treatment of dyslipidemia in humans. The physical chemical properties of bile acids are under control of farnesoid X receptor and determine intestinal cholesterol and triglyceride solubilization as well as absorption, providing a direct link between these two important factors in the pathogenesis of cardiovascular disease. Besides bile acids, intestinal phospholipids are important for luminal lipid solubilization. Interestingly, phospholipid remodeling through LPCAT3 was shown to be pivotal for uptake of fatty acids by enterocytes, which may provide a mechanistic handle for therapeutic intervention. The importance of the intestine in control of cholesterol and triglyceride homeostasis is increasingly recognized. Recently, novel factors involved in regulation of cholesterol excretion and intestinal triglyceride and fatty acid uptake have been reported and are discussed in this short review.

Switching subtype-selectivity: Fragment replacement strategy affords novel class of peroxisome proliferator-activated receptor α/δ (PPARα/δ) dual agonists

Peroxisome proliferator-activated receptors (PPARs) are important drug targets for treatment of dyslipidemia, type 2 diabetes, cardiovascular disease, nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, and great efforts have been made to develop novel PPAR ligands. However, most existing PPAR ligands contain a carboxylic acid (CA) or thiazolidinedione (TZD) structure (acidic head group) that is essential for activity. We recently discovered non-CA/TZD class PPARα/δ partial agonists, which contain an acetamide moiety and adjacent methyl group, linked to a 1,2,4-oxadiazole ring (“fragment a”). We hypothesized that the acetamide structure might interact with the CA/TZD-binding pocket. To test this idea, we firstly replaced fragment a in one of our compounds with the α-alkoxy-CA structure often found in PPAR agonists. Secondly, we replaced the α-alkoxy-CA head group of several reported PPAR agonists with our acetamide-based fragment a. The agonistic activities of the synthesized hybrid compounds toward PPARs (PPARα, PPARγ and PPARδ) were evaluated by means of cell-based reporter gene assays. All the hybrid molecules showed PPAR-agonistic activities, but replacement of the α-alkoxy-CA head group altered the maximum efficacy and the subtype-specificity. The acetamide-based hybrid molecules showed partial agonism toward PPARα and PPARδ, whereas the α-alkoxy-CA-based molecules were generally selective for PPARα and PPARγ, with relatively high activation efficacies. Thus, the fragment replacement strategy appears promising for the development of novel acetamide-based PPARα/δ dual agonists.

Dose-dependent effects of siRNA-mediated inhibition of SCAP on PCSK9, LDLR, and plasma lipids in mouse and rhesus monkey

SREBP cleavage-activating protein (SCAP) is a key protein in the regulation of lipid metabolism and a potential target for treatment of dyslipidemia. SCAP is required for activation of the transcription factors SREBP-1 and -2. SREBPs regulate the expression of genes involved in fatty acid and cholesterol biosynthesis, and LDL-C clearance through the regulation of LDL receptor (LDLR) and PCSK9 expression. To further test the potential of SCAP as a novel target for treatment of dyslipidemia, we used siRNAs to inhibit hepatic SCAP expression and assess the effect on PCSK9, LDLR, and lipids in mice and rhesus monkeys. In mice, robust liver Scap mRNA knockdown (KD) was achieved, accompanied by dose-dependent reduction in SREBP-regulated gene expression, de novo lipogenesis, and plasma PCSK9 and lipids. In rhesus monkeys, over 90% SCAP mRNA KD was achieved resulting in approximately 75, 50, and 50% reduction of plasma PCSK9, TG, and LDL-C, respectively. Inhibition of SCAP function was demonstrated by reduced expression of SREBP-regulated genes and de novo lipogenesis. In conclusion, siRNA-mediated inhibition of SCAP resulted in a significant reduction in circulating PCSK9 and LDL-C in rodent and primate models supporting SCAP as a novel target for the treatment of dyslipidemia.

SH2 domain-containing inositol 5-phosphatase (SHIP2) regulates de-novo lipogenesis and secretion of apoB100 containing lipoproteins in HepG2 cells

Hepatic de-novo lipogenesis and production of triglyceride rich VLDL are regulated via the phosphoinositide 3-kinase cascade, however, the role of a negative regulator of this pathway, the SH2 domain-containing inositol 5-phosphatase (SHIP2) in this process, remains unknown. In the present study, we investigated the molecular link between SHIP2 expression and metabolic dyslipidemia using overexpression or suppression of SHIP2 gene in HepG2 cells. The results showed that overexpression of the wild type SHIP2 gene (SHIP2-WT) led to a higher total lipid content (28%) compared to control, whereas overexpression of the dominant negative SHIP2 gene (SHIP2-DN) reduced total lipid content in oleate treated cells by 40%. Overexpression of SHIP2-WT also led to a significant increase in both secretion of apoB100 containing lipoproteins and de-novo lipogenesis, as demonstrated by an enhancement in secreted apoB100 and MTP expression, increased intra and extracellular triglyceride levels and enhanced expression of lipogenic genes such as SREBP1c, FAS and ACC. On the other hand, overexpression of the SHIP2-DN gene prevented oleate-induced de-novo lipogenesis and secretion of apoB100 containing lipoproteins in HepG2 cells. Collectively, these findings suggest that SHIP2 expression level is a key determinant of hepatic lipogenesis and lipoprotein secretion, and its inhibition could be considered as a potential target for treatment of dyslipidemia.

Dissection of the Endogenous Cellular Pathways of PCSK9-induced Low Density Lipoprotein Receptor Degradation: EVIDENCE FOR AN INTRACELLULAR ROUTE

Elevated levels of plasma low density lipoprotein (LDL)-cholesterol, leading to familial hypercholesterolemia, are enhanced by mutations in at least three major genes, the LDL receptor (LDLR), its ligand apolipoprotein B, and the proprotein convertase PCSK9. Single point mutations in PCSK9 are associated with either hyper- or hypocholesterolemia. Accordingly, PCSK9 is an attractive target for treatment of dyslipidemia. PCSK9 binds the epidermal growth factor domain A (EGF-A) of the LDLR and directs it to endosomes/lysosomes for destruction. Although the mechanism by which PCSK9 regulates LDLR degradation is not fully resolved, it seems to involve both intracellular and extracellular pathways. Here, we show that clathrin light chain small interfering RNAs that block intracellular trafficking from the trans-Golgi network to lysosomes rapidly increased LDLR levels within HepG2 cells in a PCSK9-dependent fashion without affecting the ability of exogenous PCSK9 to enhance LDLR degradation. In contrast, blocking the extracellular LDLR endocytosis/degradation pathway by a 4-, 6-, or 24-h incubation of cells with Dynasore or an EGF-AB peptide or by knockdown of endogenous autosomal recessive hypercholesterolemia did not significantly affect LDLR levels. The present data from HepG2 cells and mouse primary hepatocytes favor a model whereby depending on the dose and/or incubation period, endogenous PCSK9 enhances the degradation of the LDLR both extra- and intracellularly. Therefore, targeting either pathway, or both, would be an effective method to reduce PCSK9 activity in the treatment of hypercholesterolemia and coronary heart disease.

Atherosclerotic Peripheral Vascular Disease Symposium II

Peripheral vascular diseases are important components of cardiovascular medicine. The high prevalence of these disorders in the clinical setting mandates effective communication among healthcare providers. The public health significance of these conditions requires clear and consistent terminology for community audiences. Therefore, the goal of this writing group was to suggest definitions, usage, and nomenclature of specific terms commonly used to describe vascular diseases by cardiovascular specialists and primary care communities. The need for clarity is driven by 2 major challenges: (1) the need for use of common keywords for literature searches; and (2) the need for healthcare professionals to use common, reasoned terminology when communicating with each other and with the public. The major structural components of the vascular system are the veins, lymphatic vessels, and arteries. These serve as the basis of the nomenclature system for vascular diseases (Figure). Figure. Major classification of vascular diseases. *Includes inflammatory, artery dysplasias, congenital, traumatic, and infections. In this report, the writing group focuses only on nomenclature that applies to non–coronary artery diseases. Venous and lymphatic diseases were outside the scope of this conference. Diseases of arteries are classified further into atherosclerotic occlusive disorders, nonatherosclerotic occlusive disorders, and aneurysms. …

A proteome analysis of livers from obese (ob/ob) mice treated with the peroxisome proliferator WY14,643.

The PPAR (peroxisome proliferator activated receptor) transcription factors are ligand-activated receptors which regulate genes involved in lipid metabolism and homeostasis. PPARalpha is preferentially expressed in the liver and PPARgamma preferentially in adipose tissue. Activation of PPARalpha leads to peroxisome proliferation in rodents and increased beta-oxidation of fatty acids. PPARgamma-activation leads to adipocyte differentiation and improved insulin signaling of mature adipocytes. Both of these PPAR receptors are potential targets for treatment of dyslipidemia in man. Studies by others using a proteomics approach have characterized the effects of PPARalpha agonists in livers from lean healthy mice. However, we wanted to map the effects of a therapeutic dose of a PPARalpha agonist in a disease model of insulin resistance and diabetes, the obese diabetic ob/ob mouse, by proteomics. Therefore, ob/ob mice, which have highly elevated levels of plasma triglycerides, glucose and insulin, were treated for one week with WY14,643 (180 micromol/kg/day), a well-characterized selective PPARalpha agonist. Plasma triglycerides, glucose and insulin levels were determined and we found significant therapeutic effects on triglycerides and glucose levels. The liver protein compositions were investigated by high-resolution two-dimensional gel electrophoresis which showed that WY14,643 produced up-regulation of at least 16 spots. These were identified by mass spectrometry and 14 spots were found to be components of the peroxisomal fatty acid metabolism. Thus, WY14,643 at a therapeutic dose, caused induction of peroxisomal fatty acid beta-oxidation in obese diabetic mice.