The novel compound NO-1886 increases lipoprotein lipase activity with resulting elevation of high density lipoprotein cholesterol, and long-term administration inhibits atherogenesis in the coronary arteries of rats with experimental atherosclerosis

Targeting host-specific metabolic pathways-opportunities and challenges for anti-infective therapy

Microorganisms can takeover critical metabolic pathways in host cells to fuel their replication. This interaction provides an opportunity to target host metabolic pathways, in addition to the pathogen-specific ones, in the development of antimicrobials. Host-directed therapy (HDT) is an emerging strategy of anti-infective therapy, which targets host cell metabolism utilized by facultative and obligate intracellular pathogens for entry, replication, egress or persistence of infected host cells. This review provides an overview of the host lipid metabolism and links it to the challenges in the development of HDTs for viral and bacterial infections, where pathogens are using important for the host lipid enzymes, or producing their own analogous of lecithin-cholesterol acyltransferase (LCAT) and lipoprotein lipase (LPL) thus interfering with the human host's lipid metabolism.

The Citrus Flavonoid Nobiletin Downregulates Angiopoietin-like Protein 3 (ANGPTL3) Expression and Exhibits Lipid-Modulating Effects in Hepatic Cells and Adult Zebrafish Models

Nobiletin, a dietary citrus flavonoid, exerts biological activities against hyperlipidemia, obesity, and atherosclerotic cardiovascular diseases (ASCVDs). The aim of this study was to explore the lipid-lowering effects of nobiletin and the underlying molecular mechanisms in vitro in hepatic cells and in vivo in zebrafish models. Transcriptome and gene ontology (GO) analyses of differentially expressed genes (DEGs) by gene set enrichment analysis (GSEA) showed that a set of twenty-eight core enrichment DEGs associated with “GO BP regulation of lipid metabolic process” (GO: 0019216) were significantly downregulated in nobiletin-treated cells. Among these genes, angiopoietin-like 3 (ANGPTL3), an inhibitor of lipoprotein lipase (LPL) activity that regulates TG-rich lipoprotein (TGRL) metabolism in circulation, was the protein most markedly downregulated by nobiletin. Nobiletin (20 and 40 μM) significantly reduced the levels of ANGPTL3 mRNA and intracellular and secreted ANGPTL3 proteins in hepatic cell lines. Furthermore, alleviation of secreted ANGPTL3 production by nobiletin was found to reinstate LPL catalytic activity. Nobiletin significantly inhibited ANGPTL3 promoter activity and attenuated the transcription factor liver X receptor-α (LXRα)-mediated ANGPTL3 transcription. Molecular docking analysis predicted that nobiletin could bind to the ligand-binding domain of LXRα, thereby counteracting LXRα activation. In animal studies, orally administered nobiletin significantly alleviated the levels of plasma triglycerides (TGs) and cholesterol in zebrafish fed a high-fat diet. Moreover, nobiletin significantly reduced the amounts of hepatic ANGPTL3 protein in zebrafish. Our findings suggest that nobiletin may regulate the LXRα-ANGPTL3-LPL axis and exhibit lipid-modulating effects in vitro and in vivo. Thus, nobiletin is a potential ANGPTL3 inhibitor for the regulation of lipid metabolism to ameliorate dyslipidemia and ASCVDs.

Validation of lipid-related therapeutic targets for coronary heart disease prevention using human genetics

Drug target Mendelian randomization (MR) studies use DNA sequence variants in or near a gene encoding a drug target, that alter the target's expression or function, as a tool to anticipate the effect of drug action on the same target. Here we apply MR to prioritize drug targets for their causal relevance for coronary heart disease (CHD). The targets are further prioritized using independent replication, co-localization, protein expression profiles and data from the British National Formulary and clinicaltrials.gov. Out of the 341 drug targets identified through their association with blood lipids (HDL-C, LDL-C and triglycerides), we robustly prioritize 30 targets that might elicit beneficial effects in the prevention or treatment of CHD, including NPC1L1 and PCSK9, the targets of drugs used in CHD prevention. We discuss how this approach can be generalized to other targets, disease biomarkers and endpoints to help prioritize and validate targets during the drug development process.

Decreased Triglyceride and Increased Serum Lipoprotein Lipase Levels Are Correlated to Increased High-Density Lipoprotein-Cholesterol Levels after Laparoscopic Sleeve Gastrectomy

INTRODUCTION

Laparoscopic sleeve gastrectomy (LSG) significantly increases high-density lipoprotein cholesterol (HDL-C) and lipoprotein lipase (LPL) in pre-heparin serum (pre-heparin LPL levels). LPL is a regulator of serum triglyceride (TG) and HDL-C production; this may be the mechanism for HDL-C increase after LSG. This study aimed to elucidate the mechanism of increase in HDL-C levels by examining the relationship between changes in serum HDL-C levels and LPL after LSG.

METHODS

We retrospectively reviewed 104 obese patients, who underwent LSG and were followed up for 12 months. We analyzed the relationship between changes in serum HDL-C levels and various clinical parameters after LSG.

RESULTS

A significant decrease was observed in the patients' BMI and serum TG levels after LSG. Conversely, HDL-C levels and pre-heparin LPL levels were significantly increased after LSG. Simple linear regression showed that changes in HDL-C levels were significantly correlated with total weight loss percentage, change in TG levels, abdominal fat areas, and pre-heparin LPL levels. Additionally, the multiple regression model revealed that a decrease in TG levels and an increase in pre-heparin LPL levels were correlated with increased HDL-C levels after LSG.

DISCUSSION/CONCLUSION

These results show that a decrease in TG levels and an increase in LPL are mechanisms for increased HDL-C levels after LSG.

Novel Adipose Tissue Targets to Prevent and Treat Atherosclerosis

Adipose tissue as a major organ of lipid and lipoprotein metabolism has a major impact on metabolic homeostasis and thus influences the development of atherosclerosis and related cardiometabolic diseases. Unhealthy adipose tissue, which is often associated with obesity and systemic insulin resistance, promotes the development of diabetic dyslipidemia and can negatively affect vascular tissue homeostasis by secreting pro-inflammatory peptides and lipids. Conversely, paracrine and endocrine factors that are released from healthy adipose tissue can preserve metabolic balance and a functional vasculature. In this chapter, we describe adipose tissue types relevant for atherosclerosis and address the question how lipid metabolism as well as regulatory molecules produced in these fat depots can be targeted to counteract atherogenic processes in the vessel wall and improve plasma lipids. We discuss the role of adipose tissues in the action of approved drugs with anti-atherogenic activity. In addition, we present potential novel targets and therapeutic approaches aimed at increasing lipoprotein disposal in adipose tissue, boosting the activity of heat-producing (thermogenic) adipocytes, reducing adipose tissue inflammation, and improving or replacing beneficial hormones released from adipose tissues. Furthermore, we describe the future potential of innovative drug delivery technologies.

Ibrolipim attenuates early-stage nephropathy in diet-induced diabetic minipigs: Focus on oxidative stress and fibrogenesis

It is well-recognized that hyperlipidemia and lipid peroxidation contribute to the progression of diabetic nephropathy (DN), which is associated with oxidative stress (OS) and fibrotic lesions. Ibrolipim, a specific lipoprotein lipase activator, has been proved to reduce hyperglycemia and hyperlipidemia, suppress renal lipid deposition, and also protect renal damage. However, the underlying mechanisms of its renoprotective effect are not clearly elaborated. Herein, the present study was to identify whether the putative mechanism of Ibrolipim was related to OS and fibrogenesis in diabetic minipigs fed by high-sucrose and high-fat diet (HSFD) with or without Ibrolipim for 5 months. Compared with the normal control diet, nutrient stress induced by HSFD caused moderate glomerulosclerosis and tubulointerstitial fibrosis, and promoted renal ultrastructural and functional abnormalities. These abnormalities were correlated with renal OS and fibrogenesis characterized by the increased levels of reactive oxygen species (ROS), malondialdehyde, hydroxyproline, collagen type Ⅳ alpha 1 and fibronectin, and decreased contents of reduced glutathione and total antioxidant capacity in kidneys. Ibrolipim significantly ameliorated these abnormalities in HSFD-fed minipigs. In addition, Ibrolipim diminished HSFD-induced nicotinamide-adenine dinucleotide phosphate oxidase-4 activation to reduce ROS production, and enhanced the expression and activity of antioxidant enzymes (i.e. superoxide dismutase 1, catalase and glutathione peroxidase 1) to increase ROS elimination, resulting in obvious suppression of renal OS. Meanwhile, Ibrolipim not only inhibited the upregulation of transforming growth factor-β1 but also partially reversed the downregulation of matrix metalloproteinase 2, and then prevented extracellular matrix (ECM) accumulation. Taken together, Ibrolipim exhibits anti-oxidative and anti-fibrotic effects via modulating the rebalance of renal ROS and ECM metabolism, and ultimately attenuates the progression of nephropathy in diet-induced diabetic minipigs.

Crude α-Mangostin Suppresses the Development of Atherosclerotic Lesions in Apoe-Deficient Mice by a Possible M2 Macrophage-Mediated Mechanism

Lifestyle choices play a significant role in the etiology of atherosclerosis. Male Apoe^−/− mice that develop spontaneous atherosclerotic lesions were fed 0%, 0.3%, and 0.4% mangosteen extracts, composed largely of α-mangostin (MG), for 17 weeks. Body weight gains were significantly decreased in both MG-treated groups compared to the control, but the general condition remained good throughout the study. The levels of total cholesterol (decreased very-low-density lipoprotein in lipoprotein profile) and triglycerides decreased significantly in the MG-treated mice in conjunction with decreased hepatic HMG-CoA synthase and Fatty acid transporter. Additionally, increased serum lipoprotein lipase activity and histopathology further showed a significant reduction in atherosclerotic lesions at both levels of MG exposure. Real-time PCR analysis for macrophage indicators showed a significant elevation in the levels of Cd163, an M2 macrophage marker, in the lesions of mice receiving 0.4% MG. However, the levels of Nos2, associated with M1 macrophages, showed no change. In addition, quantitative immunohistochemical analysis of macrophage subtypes showed a tendency for increased M2 populations (CD68⁺/CD163⁺) in the lesions of mice given 0.4% MG. In further analysis of the cytokine-polarizing macrophage subtypes, the levels of Interleukin13 (Il13), associated with M2 polarization, were significantly elevated in lesions exposed to 0.4% MG. Thus, MG could suppress the development of atherosclerosis in Apoe^−/− mice, possibly through an M2 macrophage-mediated mechanism.

Constitutive Androstane Receptor Differentially Regulates Bile Acid Homeostasis in Mouse Models of Intrahepatic Cholestasis

Bile acid (BA) homeostasis is tightly regulated by multiple transcription factors, including farnesoid X receptor (FXR) and small heterodimer partner (SHP). We previously reported that loss of the FXR/SHP axis causes severe intrahepatic cholestasis, similar to human progressive familial intrahepatic cholestasis type 5 (PFIC5). In this study, we found that constitutive androstane receptor (CAR) is endogenously activated in Fxr:Shp double knockout (DKO) mice. To test the hypothesis that CAR activation protects DKO mice from further liver damage, we generated Fxr;Shp;Car triple knockout (TKO) mice. In TKO mice, residual adenosine triphosphate (ATP) binding cassette, subfamily B member 11 (ABCB11; alias bile salt export pump [BSEP]) function and fecal BA excretion are completely impaired, resulting in severe hepatic and biliary damage due to excess BA overload. In addition, we discovered that pharmacologic CAR activation has different effects on intrahepatic cholestasis of different etiologies. In DKO mice, CAR agonist 1,4‐bis[2‐(3,5‐dichloropyridyloxy)]benzene (TCPOBOP; here on TC) treatment attenuated cholestatic liver injury, as expected. However, in the PFIC2 model Bsep knockout (BKO) mice, TC treatment exhibited opposite effects that reflect increased BA accumulation and liver injury. These contrasting results may be linked to differential regulation of systemic cholesterol homeostasis in DKO and BKO livers. TC treatment selectively up‐regulated hepatic cholesterol levels in BKO mice, supporting de novo BA synthesis. Conclusion: CAR activation in DKO mice is generally protective against cholestatic liver injury in these mice, which model PFIC5, but not in the PFIC2 model BKO mice. Our results emphasize the importance of the genetic and physiologic background when implementing targeted therapies to treat intrahepatic cholestasis.

Structure-activity and in vivo evaluation of a novel lipoprotein lipase (LPL) activator

Elevated triglycerides (TG) contribute towards increased risk for cardiovascular disease. Lipoprotein lipase (LPL) is an enzyme that is responsible for the metabolism of core triglycerides of very-low density lipoproteins (VLDL) and chylomicrons in the vasculature. In this study, we explored the structure-activity relationships of our lead compound (C10d) that we have previously identified as an LPL agonist. We found that the cyclopropyl moiety of C10d is not absolutely necessary for LPL activity. Several substitutions were found to result in loss of LPL activity. The compound C10d was also tested in vivo for its lipid lowering activity. Mice were fed a high-fat diet (HFD) for four months, and treated for one week at 10mg/kg. At this dose, C10d exhibited in vivo biological activity as indicated by lower TG and cholesterol levels as well as reduced body fat content as determined by ECHO-MRI. Furthermore, C10d also reduced the HFD induced fat accumulation in the liver. Our study has provided insights into the structural and functional characteristics of this novel LPL activator.

Emerging strategies of targeting lipoprotein lipase for metabolic and cardiovascular diseases

Although statins and other pharmacological approaches have improved the management of lipid abnormalities, there exists a need for newer treatment modalities especially for the management of hypertriglyceridemia. Lipoprotein lipase (LPL), by promoting hydrolytic cleavage of the triglyceride core of lipoproteins, is a crucial node in the management of plasma lipid levels. Although LPL expression and activity modulation is observed as a pleiotropic action of some the commonly used lipid lowering drugs, the deliberate development of drugs targeting LPL has not occurred yet. In this review, we present the biology of LPL, highlight the LPL modulation property of currently used drugs and review the novel emerging approaches to target LPL.

MicroRNA-27 Prevents Atherosclerosis by Suppressing Lipoprotein Lipase-Induced Lipid Accumulation and Inflammatory Response in Apolipoprotein E Knockout Mice

Atherosclerotic lesions are lipometabolic disorder characterized by chronic progressive inflammation in arterial walls. Previous studies have shown that macrophage-derived lipoprotein lipase (LPL) might be a key factor that promotes atherosclerosis by accelerating lipid accumulation and proinflammatory cytokine secretion. Increasing evidence indicates that microRNA-27 (miR-27) has beneficial effects on lipid metabolism and inflammatory response. However, it has not been fully understood whether miR-27 affects the expression of LPL and subsequent development of atherosclerosis in apolipoprotein E knockout (apoE KO) mice. To address these questions and its potential mechanisms, oxidized low-density lipoprotein (ox-LDL)-treated THP-1 macrophages were transfected with the miR-27 mimics/inhibitors and apoE KO mice fed high-fat diet were given a tail vein injection with miR-27 agomir/antagomir, followed by exploring the potential roles of miR-27. MiR-27 agomir significantly down-regulated LPL expression in aorta and peritoneal macrophages by western blot and real-time PCR analyses. We performed LPL activity assay in the culture media and found that miR-27 reduced LPL activity. ELISA showed that miR-27 reduced inflammatory response as analyzed in vitro and in vivo experiments. Our results showed that miR-27 had an inhibitory effect on the levels of lipid both in plasma and in peritoneal macrophages of apoE KO mice as examined by HPLC. Consistently, miR-27 suppressed the expression of scavenger receptors associated with lipid uptake in ox-LDL-treated THP-1 macrophages. In addition, transfection with LPL siRNA inhibited the miR-27 inhibitor-induced lipid accumulation and proinflammatory cytokines secretion in ox-LDL-treated THP-1 macrophages. Finally, systemic treatment revealed that miR-27 decreased aortic plaque size and lipid content in apoE KO mice. The present results provide evidence that a novel antiatherogenic role of miR-27 was closely related to reducing lipid accumulation and inflammatory response via downregulation of LPL gene expression, suggesting a potential strategy to the diagnosis and treatment of atherosclerosis.

Structure-activity relationships for lipoprotein lipase agonists that lower plasma triglycerides in vivo

The risk of cardiovascular events increases in individuals with elevated plasma triglyceride (TG) levels, therefore advocating the need for efficient TG-lowering drugs. In the blood circulation, TG levels are regulated by lipoprotein lipase (LPL), an unstable enzyme that is only active as a non-covalently associated homodimer. We recently reported on a N-phenylphthalimide derivative (1) that stabilizes LPL in vitro, and moderately lowers triglycerides in vivo (Biochem. Biophys. Res. Commun.2014, 450, 1063). Herein, we establish structure-activity relationships of 51 N-phenylphthalimide analogs of the screening hit 1. In vitro evaluation highlighted that modifications on the phthalimide moiety were not tolerated and that lipophilic substituents on the central phenyl ring were functionally essential. The substitution pattern on the central phenyl ring also proved important to stabilize LPL. However, in vitro testing demonstrated rapid degradation of the phthalimide fragment in plasma which was addressed by replacing the phthalimide scaffold with other heterocyclic fragments. The in vitro potency was retained or improved and substance 80 proved stable in plasma and efficiently lowered plasma TGs in vivo.

Lipoprotein lipase and atherosclerosis

Lipoprotein lipase has long been known to hydrolyse triglycerides from triglycerides-rich lipoproteins. More recently, it has been shown to promote the binding of lipoproteins to various lipoprotein receptors. Evidence is also presented regarding the possible atherogenic role of lipoprotein lipase. In theory, lipoprotein lipase deficiency should help to clarify this question. However, the rarity of this condition means that it has not been possible to conduct epidemiological studies. An alternative approach is to investigate the correlation of lipoprotein lipase with onset of cardiovascular disease in prospective studies in large population-based cohorts. Complementary with this approach, animal models have been used to explore the atherogenicity of lipoprotein lipase expressed by macrophages.

Hypoglycemic effect of deoxynojirimycin-polysaccharide on high fat diet and streptozotocin-induced diabetic mice via regulation of hepatic glucose metabolism

Type 2 diabetes mellitus (T2DM) is currently considered a worldwide epidemic and finding effective therapeutic strategies against this disease is highly important. A deoxynojirimycin-polysaccharide mixture (DPM) has previously been shown to exert hypoglycemic effects on alloxan- or streptozotocin (STZ)-induced diabetic mice. The purpose of the present study was to evaluate the therapeutic effects and underlying mechanism(s) of DPM on T2DM induced by high fat diet following low-dose STZ treatment in mice. After daily oral treatment of diabetic mice with DPM (150 mg/kg b.w.) for 90 d, significant decline in blood glucose, pyruvate, triglyceride (TG), aspartate transaminase (AST), alanine transaminase (ALT), creatinine (Cr), lipid peroxide (LPO) and malondialdehyde (MDA) levels as well as evident increases in high density lipoprotein (HDL-c) and hepatic glycogen concentrations were observed. In the first stage, in which DPM was administered for 60 d, blood insulin levels did not undergo significant change but a significant decrease in the HOMA-IR index was detected. By contrast, the HOMA-IR index increased significantly in T2MD controls. In the second stage, in which DPM treatment was continued for another 30 d, insulin levels significantly increased in DPM-treated mice in comparison with T2DM controls. These results indicate that insulin resistance in the pre-diabetic period and the dysfunction of pancreatic β-cells are ameliorated by DPM treatment. DPM also down-regulated protein levels of insulin receptor (IR) and gluconeogenic enzymes (pyruvate carboxylase, fructose-1, 6-bisphosphatase, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase) in peripheral tissues (liver and/or muscle), but enhanced the expressions of insulin in pancreas, lipoprotein lipase (LPL) and glycolysis enzymes (glucokinase, phosphofructokinase, private kinase and pyruvate decarboxylase E1) in the liver. Furthermore, deoxynojirimycin (DNJ) and polysaccharide (P) were found to increase proliferation of hepatic LO-2 cells and scavenging of radicals in vitro. These results support the results of our biochemical analyses and underscore possible mechanisms underlying the protective effects of DPM on STZ-induced damage to the pancreas and the liver. Taken together, our findings suggest that DPM may be developed as an antihyperglycemic agent for the treatment of diabetes mellitus.

Comparative analyses of lipoprotein lipase, hepatic lipase, and endothelial lipase, and their binding properties with known inhibitors

The triglyceride lipase gene subfamily plays a central role in lipid and lipoprotein metabolism. There are three members of this subfamily: lipoprotein lipase, hepatic lipase, and endothelial lipase. Although these lipases are implicated in the pathophysiology of hyperlipidemia and atherosclerosis, their structures have not been fully solved. In the current study, we established homology models of these three lipases, and carried out analysis of their activity sites. In addition, we investigated the kinetic characteristics for the catalytic residues using a molecular dynamics simulation strategy. To elucidate the molecular interactions and determine potential key residues involved in the binding to lipase inhibitors, we analyzed the binding pockets and binding poses of known inhibitors of the three lipases. We identified the spatial consensus catalytic triad “Ser-Asp-His”, a characteristic motif in all three lipases. Furthermore, we found that the spatial characteristics of the binding pockets of the lipase molecules play a key role in ligand recognition, binding poses, and affinities. To the best of our knowledge, this is the first report that systematically builds homology models of all the triglyceride lipase gene subfamily members. Our data provide novel insights into the molecular structures of lipases and their structure-function relationship, and thus provides groundwork for functional probe design towards lipase-based therapeutic inhibitors for the treatment of hyperlipidemia and atherosclerosis.

Macrophage lipoprotein lipase modulates the development of atherosclerosis but not adiposity

The role of macrophage lipoprotein lipase (LpL) in the development of atherosclerosis and adiposity was examined in macrophage LpL knockout (MLpLKO) mice. MLpLKO mice were generated using cre-loxP gene targeting. Loss of LpL in macrophages did not alter plasma LpL activity or lipoprotein levels. Incubation of apolipoprotein E (ApoE)-deficient β-VLDL with peritoneal macrophages from ApoE knockout mice lacking macrophage LpL (MLpLKO/ApoEKO) led to less cholesteryl ester formation than that found with ApoEKO macrophages. MLpLKO/ApoEKO macrophages had reduced intracellular triglyceride levels, with decreased CD36 and carnitine palmitoyltransferase-1 mRNA levels compared with ApoEKO macrophages, when incubated with VLDL. Although both MLpLKO/ApoEKO and ApoEKO mice developed comparable hypercholesterolemia in response to feeding with a Western-type diet for 12 weeks, atherosclerosis was less in MLpLKO/ApoEKO mice. Epididymal fat mass and gene expression levels associated with inflammation did not differ between the two groups. In conclusion, macrophage LpL plays an important role in the development of atherosclerosis but not adiposity.

Metabolic syndrome: a novel high-risk state for colorectal cancer

Metabolic syndrome (MS) and related disorders, including cancer, are steadily increasing in most countries of the world. However, mechanisms underlying the link between MS and colon carcinogenesis have yet to be fully elucidated. In this review article we focus on the relationships between various individual associated conditions (obesity, dyslipidemia, diabetes mellitus type 2 and hypertension) and colon cancer development, and demonstrate probable related factors revealed by in vivo and in vitro studies. Furthermore, molecules suggested to be involved in cancer promotion are addressed, and the potential for cancer prevention by targeting these molecules is discussed.

The magic and mystery of microRNA-27 in atherosclerosis

Atherosclerosis (As) is now widely appreciated to represent a chronic inflammatory reaction of the vascular wall in response to dyslipidemia and endothelial distress involving the inflammatory recruitment of leukocytes and the activation of resident vascular cells. MicroRNAs (miRNAs) are a group of endogenous, small (~22 nucleotides in length) non-coding RNA molecules, which function specifically by base pairing with mRNA of genes, thereby induce translation repressions of the genes within metazoan cells. Recently, the function of miR-27, one of the miRNAs, in the initiation and progression of atherosclerosis has been identified. In vivo and in vitro studies suggest that miR-27 may serve as a diagnostic and prognostic marker for atherosclerosis. More recently, studies have identified important roles for miR-27 in angiogenesis, adipogenesis, inflammation, lipid metabolism, oxidative stress, insulin resistance and type 2 diabetes, etc. In this review, we focus on the role of miR-27 in the development of vulnerable atherosclerotic plaques, potential as a disease biomarker and novel therapeutic target in atherosclerosis.

NO-1886 ameliorates glycogen metabolism in insulin-resistant HepG2 cells by GSK-3β signalling

OBJECTIVES

The aim of the study was to elucidate the possible role and mechanism of NO-1886 (ibrolipim, a lipoprotein lipase activator) in ameliorating insulin resistance induced by high palmitate.

METHODS

HepG2 cells were cultured in RPMI 1640 medium and were treated with palmitate to induce insulin resistance. Free fatty acids (FFAs), glucose, glycogen, cell viability and mRNA and protein levels were analysed separately.

KEY FINDINGS

We found that HepG2 cells treated with 0.5 mm palmitate for 48 h led to a significant decrease of insulin-induced glucose consumption (from 2.89 ± 0.85 mm in the control to 0.57 ± 0.44 mm in palmitate). Insulin resistance (IR) of HepG2 cells was induced by 0.5 mm palmitate for 48 h. NO-1886 stimulated glucose consumption, glycogen synthesis and FFA absorption in insulin-resistant HepG2 cells. Maximum stimulation effects were observed with 10 µm NO-1886 for 24 h. Compared with the dimethyl sulfoxide-treated group, 2.5 µm NO-1886 or higher could induce the mRNA expression of lipoprotein lipase. Meanwhile, NO-1886 increased the protein content of P-GSK-3βser(9) and decreased the protein level of GSK-3β in insulin-resistant HepG2 cells, but NO-1886 didn't change the protein levels of PI3-Kp85 and Akt2.

CONCLUSION

Lipoprotein lipase activator NO-1886 could increase glycogen synthesis in HepG2 cells and could ameliorate the insulin resistance, which was associated with GSK-3 signalling.

Lipoprotein lipase as a candidate target for cancer prevention/therapy

Epidemiological studies have shown that serum triglyceride (TG) levels are linked with risk of development of cancer, including colorectal and pancreatic cancers, and their precancerous lesions. Thus, it is assumed that serum TG plays an important role in carcinogenesis, and the key enzyme lipoprotein lipase (LPL), which catalyzes the hydrolysis of plasma TG, may therefore be involved. Dysregulation of LPL has been reported to contribute to many human diseases, such as atherosclerosis, chylomicronaemia, obesity, and type 2 diabetes. Recently, it has been reported that LPL gene deficiency, such as due to chromosome 8p22 loss, LPL gene polymorphism, and epigenetic changes in its promoter region gene, increases cancer risk, especially in the prostate. In animal experiments, high serum TG levels seem to promote sporadic/carcinogen-induced genesis of colorectal and pancreatic cancers. Interestingly, tumor suppressive effects of LPL inducers, such as PPAR ligands, NO-1886, and indomethacin, have been demonstrated in animal models. Moreover, recent evidence that LPL plays important roles in inflammation and obesity implies that it is an appropriate general target for chemopreventive and chemotherapeutic agents.

Preventive effect of Ibrolipim on suppressing lipid accumulation and increasing lipoprotein lipase in the kidneys of diet-induced diabetic minipigs

Background

The role of renal lipoprotein lipase (LPL) per se in kidney diseases is still controversial and obscure. The purpose of this study was to observe the preventive effects of Ibrolipim, a LPL activator, on lipid accumulation and LPL expression in the kidneys of minipigs fed a high-sucrose and high-fat diet (HSFD).

Methods

Male Chinese Bama minipigs were fed a control diet or HSFD with or without 0.1 g/kg/day Ibrolipim for 5 months. Body weight, plasma glucose, insulin, lipids, LPL activity, and urinary microalbumin were measured. Renal tissue was obtained for detecting LPL activity and contents of triglyceride and cholesterol, observing the renal lipid accumulation by Oil Red O staining, and examining the mRNA and protein expression of LPL by real time PCR, Western Blot and immunohistochemistry.

Results

Feeding HSFD to minipigs caused weight gain, hyperglycemia, hyperinsulinemia, hyperlipidemia and microalbuminuria. HSFD increased plasma LPL activity while it decreased the mRNA and protein expression and activity of LPL in the kidney. The increases in renal triglyceride and cholesterol contents were associated with the decrease in renal LPL activity of HSFD-fed minipigs. In contrast, supplementing Ibrolipim into HSFD lowered body weight, plasma glucose, insulin, triglyceride and urinary albumin concentrations while it increased plasma total cholesterol and HDL-C. Ibrolipim suppressed the renal accumulation of triglyceride and cholesterol, and stimulated the diet-induced down-regulation of LPL expression and activity in the kidney.

Conclusions

Ibrolipim exerts renoprotective and hypolipidemic effects via the increase in renal LPL activity and expression, and thus the increased expression and activity of renal LPL play a vital role in suppressing renal lipid accumulation and ameliorating proteinuria in diet-induced diabetic minipigs.

Activation of lipoprotein lipase increases serum high density lipoprotein 2 cholesterol and enlarges high density lipoprotein 2 particles in rats

It is known that postheparin plasma lipoprotein lipase (LPL) activity correlates with serum high density lipoprotein cholesterol (HDL-C) levels in humans and animals. Furthermore, LPL has been reported to cause enlargement of HDL particle size in vitro. However, these effects have not yet been experimentally proven. The aim of this study was to determine whether LPL has a role in increase in HDL-C and enlargement of HDL particle by activating the LPL function with NO-1886, the LPL promoting agent. NO-1886 administration increased postheparin plasma LPL activity without influencing hepatic triglyceride lipase activity. NO-1886 increased serum HDL(2)-cholesterol (HDL(2)-C) concentration and enlarged HDL(2) particle size, but did not increase serum HDL(3)-cholesterol concentration or enlarge HDL(3) particle size. Also, serum HDL(2)-C concentrations were positively correlated with HDL(2) particle size (r=0.910). Our study demonstrates that the LPL activation induced with NO-1886 may cause production of HDL(2)-C by catabolism of triglyceride-rich lipoproteins and enlarges HDL(2) particle size in rats.

DPP4 gene DNA methylation in the omentum is associated with its gene expression and plasma lipid profile in severe obesity

Severely obese subjects with the metabolic syndrome (MS) have higher dipeptidyl peptidase-4 (DPP4) expression in their visceral adipose tissue (VAT) compared to obese individuals without MS. We tested the hypothesis that methylation level of CpG sites in the DPP4 promoter CpG island in VAT was genotype-dependent and associated with DPP4 mRNA abundance and MS-related phenotypes. The VAT DNA was extracted in 92 severely obese premenopausal women undergoing biliopancreatic derivation for the treatment of obesity. Women were nondiabetic and none of them used medication to treat MS features. Cytosine methylation rates (%) of 102 CpG sites in the DPP4 CpG island were assessed by pyrosequencing of sodium bisulfite-treated DNA. Methylation rates were >10% for CpG sites 94-102. Their mean methylation rate (%Meth(94-102)) was different between genotypes for DPP4 polymorphisms rs13015258 (P = 0.001), rs17848915 (P = 0.0004), and c.1926 G>A (P = 0.001). The %Meth(94-102) correlated negatively with DPP4 mRNA abundance (r = -0.25, P < 0.05) and positively with plasma high-density lipoprotein (HDL) cholesterol concentrations (r = 0.22, P < 0.05), whereas DPP4 mRNA abundance correlated positively with plasma total-/HDL-cholesterol ratio (r = 0.25; P < 0.05). In the VAT of nondiabetic severely obese women, genotype-dependent methylation levels of specific CpG sites in the DPP4 promoter CpG island were associated with DPP4 gene expression and variability in the plasma lipid profile. Higher DPP4 gene expression in VAT and its relationship with the plasma lipid profile may be explained by actually unknown DPP4 biological effect or, to another extent, may also be a marker of VAT inflammation known to be associated with metabolic disturbances.

Ibrolipim increases ABCA1/G1 expression by the LXRα signaling pathway in THP-1 macrophage-derived foam cells

AIM

To determine the effects and potential mechanisms of ibrolipim on ATP-binding membrane cassette transporter A-1 (ABCA1) and ATP-binding membrane cassette transporter G-1 (ABCG1) expression from human macrophage foam cells, which may play a critical role in atherogenesis.

METHODS

Human THP-1 cells pre-incubated with ox-LDL served as foam cell models. Specific mRNA was quantified using real-time RT-PCR and protein expression using Western blotting. Cellular cholesterol handling was studied using cholesterol efflux experiments and high performance liquid chromatography assays.

RESULTS

Ibrolipim 5 and 50 μmol/L significantly increased cholesterol efflux from THP-1 macrophage-derived foam cells to apoA-I or HDL. Moreover, it upregulated the expression of ABCA1 and ABCG1. In addition, LXRα was also upregulated by the ibrolipim treatment. In addition, LXRα small interfering RNA completely abolished the promotion effect that was induced by ibrolipim.

CONCLUSION

Ibrolipim increased ABCA1 and ABCG1 expression and promoted cholesterol efflux, which was mediated by the LXRα signaling pathway.

Genetic determinants of serum lipid levels in Chinese subjects: a population-based study in Shanghai, China

We examined the associations between 21 single nucleotide polymorphisms (SNPs) of eight lipid metabolism genes and lipid levels in a Chinese population. This study was conducted as part of a population-based study in China with 799 randomly selected healthy residents who provided fasting blood and an in-person interview. Associations between variants and mean lipid levels were examined using a test of trend and least squares mean test in a general linear model. Four SNPs were associated with lipid levels: LDLR rs1003723 was associated with total cholesterol (P-trend = 0.002) and LDL (P-trend = 0.01), LDLR rs6413503 was associated with total cholesterol (P-trend = 0.05), APOB rs1367117 was associated with apoB (P-trend = 0.02), and ABCB11 rs49550 was associated with total cholesterol (P-trend = 0.01), triglycerides (P-trend = 0.01), and apoA (P-trend = 0.01). We found statistically significant effects on lipid levels for LDLR rs6413503 among those with high dairy intake, LPL rs263 among those with high allium vegetable intake, and APOE rs440446 among those with high red meat intake. We identified new associations between SNPs and lipid levels in Chinese previously found in Caucasians. These findings provide insight into the role of lipid metabolism genes, as well as the mechanisms by which these genes may be linked with disease.

Beneficial effect of 3,4,5,6-tetrahydroxyxanthone on dyslipidemia in apolipoprotein E-deficient mice

Previous investigations have shown that decreased expression of angiopoietin-like protein 3 (Angptl3) is protective against dyslipidemia in atherosclerosis. The present study was conducted to test the effect of 3,4,5,6-tetrahydroxyxanthone, a xanthone compound, on dyslipidemia in apolipoprotein E-deficient (ApoE-/-) mice. Forty mice were randomly divided into 4 groups (n = 10): control group (C57BL/6J mice), ApoE-/-mice group, and two groups of ApoE-/- mice treated with 3,4,5,6-tetrahydroxyxanthone (10 or 30 mg/kg per day). Eight weeks after treatment, lipid levels in the blood and liver, expression of hepatic Angptl3, and adipose tissue lipoprotein lipase (LPL) were determined. Treatment with 3,4,5,6-tetrahydroxyxanthone (10 or 30 mg/kg) significantly decreased plasma and hepatic total cholesterol and triglyceride concentrations, increased plasma high-density lipoprotein cholesterol, and significantly downregulated expression of Angptl3 mRNA and protein concomitantly with upregulated expression of LPL mRNA. In addition, T0901317 (a liver X receptor ligand) caused elevated expression of hepatic Angptl3 mRNA and protein, and the effect of T0901317 was also abrogated by 3,4,5,6-tetrahydroxyxanthone in vivo and in vitro. The present results suggest that the beneficial effect of 3,4,5,6-tetrahydroxyxanthone on dyslipidemia may be related to reduced expression of Angptl3.

NO-1886, a lipoprotein lipase activator, attenuates contraction of rat intestinal ring preparations

Various intestinal symptoms or diseases are closely associated with intestinal motility, which may be altered by metabolic disturbances associated with diabetes and obesity. It is therefore important that drugs used in the treatment of metabolic disorders should not have any adverse effects on the intestine. In the present study, we examined whether [4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester (NO-1886), a lipoprotein lipase activator with anti-diabetic and/or anti-obese activity, affects stimulant-induced intestinal contractility. Administration of NO-1886 to intestinal ring preparations of ileum, rectum and colon isolated from Wistar rats attenuated or relaxed contraction induced by a high K+ environment or acetylcholine (ACh). This effect of NO-1886 was dependent on extracellular Ca(2+) and intracellular myosin light chain kinase activity. Our results also showed that ACh-induced colonic contraction was significantly higher in the obese Otsuka Long-Evans Tokushima Fatty (OLETF) than in the non-obese Long-Evans Tokushima Otsuka (LETO) rats. The hypercontractility observed in the colons of OLETF rats occurred concomitantly with an elevation in muscarinic M3 ACh receptor protein levels. Administration of NO-1886 attenuated the obesity-induced hypercontractility of the colonic rings of OLETF rats. Thus, intestinal contractile system would be a novel pharmacological target of the lipoprotein lipase activator NO-1886.

Dietary chickpeas reverse visceral adiposity, dyslipidaemia and insulin resistance in rats induced by a chronic high-fat diet

The improved effects of dietary chickpeas on visceral adiposity, dyslipidaemia and insulin resistance were examined. Rats were fed a normal-fat diet (NFD), a high-fat diet (HFD) or a high-fat plus chickpea diet (HFD+CP) for 8 months. The epididymal fat pad weight v. total body weight of rats was higher in the HFD group (0.032 (sd 0.0042) g/g) than in the NFD group (0.015 (sd 0.0064) g/g) and smaller in the HFD+CP group (0.023 (sd 0.0072) g/g) compared with the HFD group (P < 0.05). Chickpea treatment also induced a favourable plasma lipid profile reflecting decreased TAG, LDL-cholesterol (LDL-C) and LDL-C:HDL-cholesterol levels (P < 0.05). HFD-fed rats had higher TAG concentration in muscle and liver, whereas the addition of chickpeas to the HFD drastically lowered TAG concentration (muscle, 39 %; liver, 23 %). The activities of lipoprotein lipase (LPL) in epididymal adipose tissue and hepatic TAG lipase in liver recorded a 40 and 23 % increase respectively in HFD rats compared with those in NFD rats; dietary chickpeas completely normalised the levels. Furthermore, chickpea-treated obese rats also showed a markedly lower leptin and LPL mRNA content in epididymal adipose tissue. An insulin tolerance test, oral glucose tolerance test and insulin-releasing test showed that chickpeas significantly improved insulin resistance, and prevented postprandial hyperglycaemia and hyperinsulinaemia induced by the chronic HFD. The present findings provide a rational basis for the consumption of chickpeas as a functional food ingredient, which may be beneficial for correcting dyslipidaemia and preventing diabetes.

Lipoprotein lipase activator ameliorates the severity of dietary steatohepatitis

Dietary model of steatohepatitis was established by feeding mice a methionine choline deficient (MCD) diet. Mice on MCD or control diet for 3 weeks were treated with or without NO-1886, a newly synthetic lipoprotein lipase (LPL) activator. In a separate experiment, NO-1886 was given after pre-treatment with 3 weeks of MCD diet. NO-1886 significantly reduced MCD-induced inflammation by repressing levels of hepatic lipid peroxides and pro-inflammatory tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2). In addition, NO-1886 dampened hepatic steatosis via accelerating fatty acid oxidation caused by enhanced expression of PPARalpha, cytochrome P450-10 (Cyp4a10), and Acyl-CoA oxidase (ACO). It failed to regulate genes of fatty acid uptake and synthesis pathways. In conclusion, NO-1886 ameliorated and induced regression of experimental steatohepatitis via increasing endogenous LPL activation resulting in suppression on pro-inflammatory factors and reduction of hepatic fatty acids. These findings indicate that NO-1886 is a potential therapeutic agent for steatohepatitis.

NO-1886, a lipoprotein lipase activator, attenuates vascular smooth muscle contraction in rat aorta

The chemical compound [4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester (NO-1886) is a lipoprotein lipase activator having beneficial effects on both diabetes control and the cardiovascular system. Preventing accumulation of lipids in the cell wall, in addition to improving insulin actions on vasculature, may indirectly contribute to the reducing effect of NO-1886 on vascular resistance. However, the direct effect of NO-1886 on vascular resistance, i.e., whether NO-1886 directly modulates the function of vascular endothelium and/or smooth muscle cells has not been investigated. In this study we therefore investigated the direct effect of NO-1886 on vascular contractility using rat aortic rings and cultured smooth muscle cell-line A10. The results show that administration of NO-1886 attenuated aortic contraction induced by phenylephrine and/or a high K(+) environment, in both the presence and absence of aortic endothelium. 1-(5-Chloronaphthalene-1-sulfonyl)homopiperazine hydrochloride (ML-9), a myosin light chain kinase (MLCK) inhibitor, blocked this inhibitory effect of NO-1886, whereas inhibitors of other signaling molecules such as calmodulin, protein kinase C and Rho-kinase had no effect. The vasorelaxant effect of NO-1886 was blocked in the absence of extracellular Ca(2+), or in the presence of the Ca(2+) channel inhibitor, verapamil. NO-1886 attenuated smooth muscle contraction induced by the cumulative addition of CaCl(2). In A10 cells, NO-1886 inhibited the membrane depolarization-induced initial peak of [Ca(2+)](i) in the presence of extracellular Ca(2+). This inhibition did not occur in the absence of extracellular Ca(2+). Taken together these results demonstrate that NO-1886 attenuates smooth muscle contraction and causes vasorelaxation by an extracellular Ca(2+)- and MLCK-dependent mechanism.

Impact of weight-loss medications on the cardiovascular system: focus on current and future anti-obesity drugs

Overweight and obesity have been rising dramatically worldwide and are associated with numerous co-morbidities such as cardiovascular disease (CVD), type 2 diabetes mellitus, hypertension, certain cancers, and sleep apnea. In fact, obesity is an independent risk factor for CVD and CVD risks have also been documented in obese children. The majority of overweight and obese patients who achieve a significant short-term weight loss do not maintain their lower bodyweight in the long term. This may be due to a lack of intensive counseling and support from a facilitating environment including dedicated healthcare professionals such as nutritionists, kinesiologists, and behavior specialists. As a result, there has been a considerable focus on the role of adjunctive therapy such as pharmacotherapy for long-term weight loss and weight maintenance. Beyond an unfavorable risk factor profile, overweight and obesity also impact upon heart structure and function. Since the beginning, the quest for weight loss drugs has encountered warnings from regulatory agencies and the withdrawal from the market of efficient but unsafe medications. Fenfluramine was withdrawn from the market because of unacceptable pulmonary and cardiac adverse effects. Nevertheless, there is extensive research directed at the development of new anti-obesity compounds. The effect of these molecules on CVD risk factors has been studied and reported but information regarding their impact on the cardiovascular system is sparse. Thus, instead of looking at the benefit of weight loss on metabolism and risk factor management, this article discusses the impact of weight loss medications on the cardiovascular system. The potential interaction of available and potential new weight loss drugs with heart function and structure is reviewed.

Effect of Skim Milk and Dahi (Yogurt) on Blood Glucose, Insulin, and Lipid Profile in Rats Fed with High Fructose Diet

In the present study, the effect of skim milk and the fermented milk product named dahi (yogurt) on plasma glucose, insulin, and lipid levels as well as on liver glycogen and lipid contents in rats fed with high fructose diet has been investigated. Rats were fed with high fructose diet (21%) supplemented with skim milk, dahi (10 g/day each), or no milk product (control group) for 6 weeks. After 6 weeks of high fructose diet administration, the plasma glucose became significantly higher in control animals (246 mg/dL), whereas it was lower in skim milk (178 mg/dL)- and dahi (143 mg/dL)-fed rats. The glucose tolerance became impaired at the third week of feeding of high fructose diet in control animals, whereas in skim milk- and dahi-fed animals achievement of glucose intolerance was delayed until the fourth and fifth week, respectively. Blood glycosylated hemoglobin and plasma insulin were significantly lower in skim milk (10% and 34%, respectively)- and dahi (17%, and 48%, respectively)-fed animals than those of the control group. Plasma total cholesterol, triglycerides, low-density lipoprotein-cholesterol, and very-low-density lipoprotein-cholesterol and blood free fatty acids were significantly lower in skim milk (13%, 14%, 14%, 19%, and 14%, respectively)- and dahi (22%, 33%, 30%, 33%, and 29%, respectively)-fed animals as compared with control animals. Moreover, the total cholesterol, triglyceride, and glycogen contents in liver tissues were also lower in skim milk (55%, 50%, and 36%, respectively)- and dahi (64%, 27%, and 4%, respectively)-fed animals as compared with control animals. In contrast, high-density lipoprotein-cholesterol in plasma was higher in skim milk (14%)- and dahi (29%)-fed animals as compared with control animals. These results indicate that skim milk and its fermented milk product, dahi, delay the progression of fructose-induced diabetes and dyslipidemia in rats and that these may be useful as antidiabetic food supplements that can be included in daily meals of the diabetic as well as normal population.

NO-1886 upregulates ATP binding cassette transporter A1 and inhibits diet-induced atherosclerosis in Chinese Bama minipigs

It is widely believed that high density lipoprotein-cholesterol (HDL-C) functions to transport cholesterol from peripheral cells to the liver by reverse cholesterol transport (RCT), a pathway that may protect against atherosclerosis by clearing excess cholesterol from arterial cells. A cellular ATP binding cassette transporter called ABCA1 mediates the first step of RCT. NO-1886 has been proven to be highly effective at increasing HDL-C and reducing atherosclerosis. However, the mechanism of atherosclerosis inhibition for NO-1886 is not fully understood. In this study, the effects of NO-1886 on ABCA1 were investigated in high-fat/high-sucrose/high-cholesterol-fed Chinese Bama minipigs. Administration of NO-1886 (0.1 g/kg body weight/day) in the diet for 5 months significantly reduced atherosclerosis lesions and significantly increased plasma HDL-C and apolipoprotein A-I levels. The mRNA and protein levels of ABCA1 in the liver, retroperitoneal adipose tissue, and aorta were increased by NO-1886 as well. Multivariate linear regression analysis showed that the levels of LPL in plasma and the levels of ABCA1 in aorta were independently associated with the atherosclerotic lesion area. In addition, NO-1886 upregulated liver X receptor alpha and affected the expression of scavenger receptor class B type I in the liver. These results demonstrate that the mechanism of atherosclerosis inhibition for NO-1886 is associated with its effect on ABCA1.

Concomitant suppression of hyperlipidemia and intestinal polyp formation by increasing lipoprotein lipase activity in Apc-deficient mice

Epidemiologically, a high-fat diet is associated with the risk of colon cancer. In addition, serum levels of triglycerides (TGs) and cholesterol have been demonstrated to be positively associated with colon carcinogenesis. We recently found that an age-dependent hyperlipidemic state (high serum TG levels) exists in Apc-deficient mice, an animal model for human familial adenomatous polyposis. The mRNA levels of lipoprotein lipase (LPL), which catalyzes TG hydrolysis, were shown to be downregulated in the liver and intestines of mice. Moreover, treatment with a peroxisome proliferator-activated receptor (PPAR) alpha agonist, bezafibrate, or a PPARgamma agonist, pioglitazone, suppressed both hyperlipidemia and intestinal polyp formation in the mice, with induction of LPL mRNA. PPARalpha and PPARgamma agonists are reported to exert anti-proliferative and pro-apoptotic effects in cancer cells. One compound that also increases LPL expression levels but does not possess PPAR agnostic activity is NO-1886. When given at 400 or 800 ppm in the diet, it suppresses both hyperlipidemia and intestinal polyp formation in Apc-deficient mice, with elevation of LPL mRNA. In conclusion, a decrease in serum lipid levels by increasing LPL activity may contribute to a reduction in intestinal polyp formation with Apc deficiency. PPARalpha and PPARgamma agonists, as well as NO-1886, could be useful as chemopreventive agents for colon cancer.

Assessment of induction of cytochrome P450 by NO-1886 (ibrolipim), a lipoprotein lipase-promoting agent, in primary cultures of human hepatocytes and in female rat liver

The mRNA levels of human cytochrome P450 (CYP)2Cs and CYP3As in primary cultures of freshly isolated human hepatocytes were assessed after exposure to NO-1886 and rifampicin, a typical inducer of CYP3As. mRNA levels were analyzed by real-time RT-PCR using an ABI PRISM 7700 Sequence Detector system. Exposure to NO-1886 for 24 hr at a concentration of less than 10 microM showed only a tendency to reduce or increase the expression levels of CYP2C8, CYP2C9, CYP2C19, CYP3A4, or CYP3A5 mRNA. A higher concentration (50 microM) of NO-1886 induced an increase in CYP2C8 mRNA and a decrease in CYP2C19 mRNA, and these changes continued after additional culture for 24 hr in fresh medium without NO-1886. The expression level of CYP3A4 mRNA after exposure to NO-1886 for 24 hr at 50 microM was about twice that in controls. Following additional culture for 24 hr in fresh medium without NO-1886, the expression of CYP3A4 mRNA was comparable to that in controls. On the other hand, the expression levels of CYP2C9 and CYP3A5 mRNA showed small and variable changes in each donor even at a high concentration (50 microM) of NO-1886. Furthermore, the pharmacokinetics of NO-1886 during repeated oral administration for 14 days was studied in female rats. The pharmacokinetic parameters of NO-1886 were nearly the same on days 1, 7, and 14 of repeated administration. The hepatic microsomal content of CYP isoforms was not affected by repeated administration for 7 days at a dose of 1 to 30 mg/kg in female rats, although the total CYP content was increased at a dose of 30 mg/kg. The expression levels of CYP1A2, CYP2B2, CYP2C12, and CYP2E1 mRNA in primary cultures of rat hepatocytes were not affected by exposure to NO-1886 at 2, 10, or 50 microM. The expression levels of CYP3A1 mRNA in primary cultures of rat hepatocytes were not affected by exposure to NO-1886 at 2 or 10 microM, but were increased, with large individual variation, by exposure at 50 microM. The mRNA expression levels in rat hepatocytes exposed to concentrations comparable to free plasma levels did not change significantly, which was consistent with the equivalence in the in vivo plasma concentrations observed on days 1 and 14 of repeated administration. These results suggest that repeated administration of NO-1886 at clinical doses does not significantly affect the expression levels of CYP isoforms in human liver, although the mRNA levels of the CYP isoforms involved in the metabolism of NO-1886 were increased by exposure to higher concentrations of NO-1886 in human hepatocytes in vitro.

NO-1886 (ibrolipim), a lipoprotein lipase-promoting agent, accelerates the expression of UCP3 messenger RNA and ameliorates obesity in ovariectomized rats

The synthetic compound NO-1886 (ibrolipim, [4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester, CAS 133208-93-2) is a lipoprotein lipase (LPL)-promoting agent that decreases plasma triglycerides, increases high-density lipoprotein cholesterol levels, and prevents fat accumulation in high fat-fed rats. However, the effect of NO-1886 on body weight, fat accumulation, and energy expenditure in ovariectomized (OVX) rats is not clear. The primary aim of this study was to ascertain whether NO-1886 ameliorated obesity in OVX rats and to examine the effects on fatty acid oxidation-related enzymes. NO-1886 decreased accumulation of visceral fat and suppressed the increase in body weight resulting from the ovariectomy. NO-1886 decreased the respiratory quotient and increased expression of the fatty acid translocase messenger RNA (mRNA) in the liver, soleus muscle, and mesenteric fat. NO-1886 also increased the expression of fatty acid-binding protein mRNA in the liver and soleus muscle and the expression of the uncoupling protein 3 (UCP3) mRNA in the heart, soleus muscle, and mesenteric fat, but not in the brown adipose tissue. Furthermore, NO-1886 did not affect UCP1 and UCP2 in brown adipose tissue. Therefore, amelioration of obesity by NO-1886 in OVX rats is possibly because of an the increased expression of fatty acid oxidation-related enzymes and UCP3, both of which are related to fatty acid transfer and fat use. Our study indicates that the LPL-promoting agent NO-1886 may be potentially beneficial in the treatment of obesity and obesity-linked health problems in postmenopausal women.

NO-1886 (ibrolipim), a lipoprotein lipase activator, increases the expression of uncoupling protein 3 in skeletal muscle and suppresses fat accumulation in high-fat diet-induced obesity in rats

Although the lipoprotein lipase (LPL) activator NO-1886 shows antiobesity effects in high-fat-induced obese animals, the mechanism remains unclear. To clarify the mechanism, we studied the effects of NO-1886 on the expression of uncoupling protein (UCP) 1, UCP2, and UCP3 in rats. NO-1886 was mixed with a high-fat chow to supply a dose of 100 mg/kg to 8-month-old male Sprague-Dawley rats. The animals were fed the high-fat chow for 8 weeks. At the end of the administration period, brown adipose tissue (BAT), mesenteric fat, and soleus muscle were collected and levels of UCP1, UCP2, and UCP3 messenger RNA (mRNA) were determined. NO-1886 suppressed the body weight increase seen in the high-fat control group after the 8-week administration (585 +/- 39 vs 657 +/- 66 g, P < .05). NO-1886 also suppressed fat accumulation in visceral (46.9 +/- 10.4 vs 73.7 +/- 14.5 g, P < .01) and subcutaneous (43.1 +/- 18.1 vs 68.9 +/- 18.8 g, P < .05) tissues and increased the levels of plasma total cholesterol and high-density lipoprotein cholesterol in comparison to the high-fat control group. In contrast, NO-1886 decreased the levels of plasma triglycerides, nonesterified free fatty acid, glucose, and insulin. NO-1886 increased LPL activity in soleus muscle (0.082 +/- 0.013 vs 0.061 +/- 0.016 mumol of free fatty acid per minute per gram of tissue, P < .05). NO-1886 increased the expression of UCP3 mRNA in soleus muscle 3.14-fold (P < .01) compared with the high-fat control group without affecting the levels of UCP3 in mesenteric adipose tissue and BAT. In addition, NO-1886 did not affect the expression of UCP1 and UCP2 in BAT, mesenteric adipose tissue, and soleus muscle. In conclusion, NO-1886 increased the expression of UCP3 mRNA and LPL activity only in skeletal muscle. Therefore, a possible mechanism for NO-1886's antiobesity effects in rats may be the enhancement of LPL activity in skeletal muscle and the accompanying increase in UCP3 expression.

FR177391, A New Anti-hyperlipidemic Agent from Serratia

The pharmacological effect of FR177391, isolated from Serratia liquefaciens No. 1821, was studied in normal animals and various types of animal models of hypertriglyceridemia. Treatment of normal mice with FR177391 resulted in an increase in heparin-releasable lipoprotein lipase (LPL) activity in the blood and epididymal fat tissue. FR177391 treatment decreased triglyceride (TG) and increased high-density lipoprotein cholesterol in the blood in normal rats following 7 days treatment, suggesting potent LPL activating properties of FR177391. Both Triton WR1339-induced severe and fructose-induced mild hypertriglyceridemia in rats were attenuated by FR177391 treatment. Severely elevated levels of TG in db/db mice, an insulin resistant diabetic animal model, also significantly decreased from 14 days of treatment with FR177391. FR177391 treatment for 9 days caused a decrease in the elevated levels of TG in mice induced by intraperitoneal inoculation of murine lymphoma EL-4. Overall, this study demonstrated that FR177391 can be possibly a LPL activating agent and that FR177391 treatment improved hypertriglyceridemia in various rat and mouse animal models. These results suggest that FR177391 is a promising candidate compound for the management of hypertriglyceridemia.

New Insights Into the Regulation of HDL Metabolism and Reverse Cholesterol Transport

The metabolism of high-density lipoproteins (HDL), which are inversely related to risk of atherosclerotic cardiovascular disease, involves a complex interplay of factors regulating HDL synthesis, intravascular remodeling, and catabolism. The individual lipid and apolipoprotein components of HDL are mostly assembled after secretion, are frequently exchanged with or transferred to other lipoproteins, are actively remodeled within the plasma compartment, and are often cleared separately from one another. HDL is believed to play a key role in the process of reverse cholesterol transport (RCT), in which it promotes the efflux of excess cholesterol from peripheral tissues and returns it to the liver for biliary excretion. This review will emphasize 3 major evolving themes regarding HDL metabolism and RCT. The first theme is that HDL is a universal plasma acceptor lipoprotein for cholesterol efflux from not only peripheral tissues but also hepatocytes, which are a major source of cholesterol efflux to HDL. Furthermore, although efflux of cholesterol from macrophages represents only a tiny fraction of overall cellular cholesterol efflux, it is the most important with regard to atherosclerosis, suggesting that it be specifically termed macrophage RCT. The second theme is the critical role that intravascular remodeling of HDL by lipid transfer factors, lipases, cell surface receptors, and non-HDL lipoproteins play in determining the ultimate metabolic fate of HDL and plasma HDL-c concentrations. The third theme is the growing appreciation that insulin resistance underlies the majority of cases of low HDL-c in humans and the mechanisms by which insulin resistance influences HDL metabolism. Progress in our understanding of HDL metabolism and macrophage reverse cholesterol transport will increase the likelihood of developing novel therapies to raise plasma HDL concentrations and promote macrophage RCT and in proving that these new therapeutic interventions prevent or cause regression of atherosclerosis in humans.