TG Hydrolysis Research Articles

Alleviation effect of conjugated linoleic acid on estradiol benzoate induced fatty liver hemorrhage syndrome in Hy-line male chickens.

The purpose of this study was to explore whether conjugated linoleic acid (CLA) could alleviate fatty liver hemorrhagic syndrome (FLHS) induced by estradiol benzoate intramuscular injection in laying hens. One hundred male Hy-Line white chickens were randomly divided into two groups, namely, the control (CON) and estradiol benzoate (E) groups, and both groups were fed the same basal diet. After injections of estradiol benzoate at 2 mg/kg every two days for a total of 7 times, chickens in the E group showed FLHS symptoms, including liver enlargement, hemorrhage, and steatosis. Then half of the chickens in the E group received an additional diet containing 5000 mg/kg CLA for 8 weeks. The results of morphological observations, hematoxylin and eosin staining, and Oil Red O staining showed that CLA alleviated liver enlargement, hemorrhage, and lipid accumulation in FLHS chickens. In addition, we measured liver function and lipid metabolism indicators, including ALT, AST, TG, TCH, HDL-C, and LDL-C, which further suggested that CLA mitigated the disturbance of serum and liver metabolism in FLHS chickens. Mechanistically, CLA inhibited hepatic de novo lipogenesis, cholesterol synthesis, and TG accumulation and increased TG hydrolysis in FLHS chickens by regulating the gene expression of CD36, ACC, FAS, SCD 1, DGAT2, LIPE, ATGL, CPT1A, SREBP-1c, SREBP-2, PPARγ, and PPARα. Furthermore, CLA ameliorated hepatic oxidative stress and inhibited NF-κB signaling pathway-mediated inflammation in FLHS chickens. In conclusion, CLA regulated lipid metabolism, thus further alleviating oxidative stress and inflammation to alleviate FLHS induced by estrogen in chickens.

Hypertriglyceridemia-induced acute pancreatitis in children: A mini-review.

Severe hypertriglyceridemia (HTG) is a known metabolic cause of acute pancreatitis (AP) in pediatric patients. The incidence of hypertriglyceridemia-induced acute pancreatitis (HTG-AP) is less well established in pediatric compared to adult patients. Studies in adults suggest that higher risk of AP occurs when triglyceride levels (TG) are >1,000 mg/dL. Most common etiologies for severe HTG in pediatric patients are either from primary hypertriglyceridemia, underlying genetic disorders of lipid and TG metabolism, or secondary hypertriglyceridemia, separate disease or exposure which affects TG metabolism. Most common theories for the pathophysiology of HTG-AP include hydrolysis of TG by pancreatic lipase to free fatty acids leading to endothelial and acinar cell damage and ischemia, as well as hyperviscosity related to increased chylomicrons. Though there are varying reports of HTG-AP severity compared to other causes of AP, a steadily growing body of evidence suggests that HTG-AP can be associated with more severe course and complications. Therapeutic interventions for HTG-AP typically involve inpatient management with dietary restriction, intravenous fluids, and insulin; select patients may require plasmapheresis. Long term interventions generally include dietary modification, weight management, control of secondary causes, and/or antihyperlipidemic medications. Though some therapeutic approaches and algorithms exist for adult patients, evidence-based management guidelines have not been well established for pediatric patients.

A Comparative Study of the Triglycerides/HDL Ratio and Pseudocholinesterase Levels in Patients with Bladder Cancer.

Background: Lipid alterations may serve as potential tumour biomarkers. The ratio of triglycerides to HDL cholesterol (TG/HDL ratio) is associated with various cancers. Pseudocholinesterase (PChE) activity, involved in TG hydrolysis, plays an important role in the metabolism of lipoprotein. There is scarce data assessing the reliability of both the TG/HDL ratio and PChE levels in correctly classifying patients suffering from bladder cancer. Methods: Three hundred and ninety-six patients undergoing cystoscopy or transurethral resection of the bladder (TURB), broken into two major groups, i.e., patients with histologically confirmed, non-metastatic bladder cancer (n = 208) and without bladder cancer (no bladder cancer, n = 188), formed the study population. The last group was split into two subgroups consisting of a cohort of patients never suffering from bladder cancer but with other bladder diseases (no CaBD, n = 100) and another cohort formed by patients characterised by eradicated bladder cancer after TURB with no recurrence during a three-month follow-up (previous bladder cancer, n = 88). Pieces of information by both metabolic derangement (the presence of type 2 diabetes mellitus), hypertension and lipid profile were retrieved from patient records upon entry to the study. Sensitivity, specificity, areas under the ROC (AUROC) of the TG/HDL ratio, and PChE levels were used in diagnostic decision making. Results: The TG/HDL ratio as well as PChE concentrations of bladder cancer patients were significantly different when compared to those with previous bladder cancer and the no CaBD patients (p = 0.023 and 0.0004, respectively). There was an independent role of both the TG/HDL ratio and PChE levels in predicting the presence of bladder cancer (OR: 1.22 and 0.99, respectively), but the reliability of the TG/HDL ratio (AUROC: 0.587) was superior to that of PChE levels (AUROC: 0.374). The AUROC of a new parameter resulting from the combination of the TG/HDL ratio with PChE levels showed a further increment in the discriminant power of the bladder cancer presence (0.6298), interestingly with a negative predictive value (89%) according to the Bayesian approach. The cut-off of the TG/HDL ratio, the main marker of the present study that better distinguishes bladder cancer from no bladder cancer patients, was 2.147. Discussion and Conclusions: The reliability of the TG/HDL ratio is based on the fact that this parameter likely mirrors the insulin resistance (IR) underlying bladder cancer patients. Furthermore, PChE levels evidence both IR and the associated non-alcoholic fatty liver disease. The TG/HDL ratio and PChE levels as well as their combined use could help physicians to assess/confirm the presence of this very common cancer, where early detection is important to ensure the best therapeutical approach.

POWER RATE LAW BASED CHEMICAL KINETICS AND THERMODYNAMIC MODELING OF AFRICAN PEAR SEED OIL CONSECUTIVE IRREVERSIBLE BASE METHANOLYSIS FOR BIODIESEL PRODUCTION

Currently the major challenge of biodiesel application as a replacement to petrodiesel is its industrial production sustainability.Consequently, the successful scale-up of laboratory results in transesterification requires so much information obtained through chemical kinetics.This paper presents the kinetics and thermodynamic study of alkali-homogeneous irreversible methanolysis of seed oil derived from African pear. The transesterification process was carried out from 0-100 minutes at temperature range of 55-65°C. The reaction mixture compositions were ascertained using gas chromatography- flame ionization detector (GC-FID) technique. Rate constants of the triglyceride (Tg), diglycerides (Dg) and monoglycerides(Mg) hydrolysis were in the range of 0.0140- 0.07810 wt%/min and increased with increase in temperature. The rate of reaction was found to increase with increase in temperature. Activation energies were found to be 6.14, 20.01 and 28.5kcal/mol at 55, 60 and 65oC respectively. Tg hydrolysis to Dg was observed asthe rate determining step while the reaction agreed with second order principles. A biodiesel yield of 93.02% was obtained with cloud point of 10°C , flash point of 125°C , pour point of 4°C , calorific value of 34.4MJ/kg, and cetane number of 54.90 which satisfy EN14214 and ASTM D 6751 standards. Results presented in this report would serve as idealized conditions for industrial scale up of biodiesel production from African pear seed oil. Keywords:Kinetics; methanolysis; rate constants; activation energy; African pear seed oil; biodiesel

Abstract 283: Western Diet Induces Diastolic Dysfunction Linked to Impaired Cardiac Lipid Storage Dynamics That Predate Systolic Dysfunction

Western diet (WD), containing high fat and high refined sugar, is associated with increased risk of cardiovascular disease. However, mechanisms linking WD to cardiomyopathy are far from understood. We hypothesize that WD induces cardiac dysfunction by dysregulation of cardiac lipid dynamics. Adult C57BL/6J mice were fed with either standard chow (CON, fat 4.5 %, sucrose 0%) or western diet (WD, fat 45%, sucrose 21%). At 20 weeks, WD mice exhibited higher body mass, reduced glucose tolerance, and increased isovolumetric relaxation time (IVRT), with no systolic dysfunction vs. CON. However, at 24 weeks, WD caused both systolic and diastolic dysfunction with decreases in left ventricular ejection fraction (66±2% CON vs. 54±2 WD, P <0.05) and fractional shortening (35±2% CON vs. 27±1 WD), with elevated IVRT and E/E’ ratio vs CON. Real time, dynamic-mode 13 C NMR and endpoint LC/MS of isolated perfused hearts supplied 13 C palmitate and 13 C oleate, with unlabeled glucose and lactate, revealed elevated TG content (28% increase vs. CON) with reduced TG turnover in WD hearts (35% decrease vs. CON), concurrent with early diastolic dysfunction at 20 weeks and preceding systolic dysfunction at 24 weeks. WD induced lower content of the TG lipase, ATGL (48% vs. CON), with no change in the TG synthase, DGAT1, suggesting elevated cardiac TG and lower TG turnover are due to reduced TG hydrolysis and not TAG synthesis. Impaired lipid storage dynamics can cause increased generation of potentially lipotoxic acyl intermediates, leading to cardiac dysfunction. The mitochondrial long chain fatty acid transporter, CPT1b was reduced (50%), with no change in the lesser, co-expressed CPT1a isoform in WD hearts. Despite reduced CPT1b in WD hearts, contributions from LCFAs to acetyl CoA production in the citric acid cycle were unchanged, suggesting that the WD provided sufficient LCFAs for mitochondrial oxidation and that the reduced CPT1b was not limiting. In conclusion, western diet expands the TG pool but impairs fat storage dynamics via low ATGL, leading to early diastolic dysfunction and eventual systolic dysfunction. Nutrient overload from WD leads to impaired cardiac lipid dynamics with early diastolic dysfunction that is distinguished from HFpEF due to later systolic dysfunction.

Is APOC3 the driver of cardiovascular disease in people with type I diabetes mellitus?

In this issue of the JCI, Kanter et al. make a strong case for implicating apolipoprotein C3 (APOC3) as a central player in atherosclerotic cardiovascular disease that is commonly seen in individuals with type 1 diabetes mellitus (T1DM). Kanter and colleagues suggest that insulin deficiency elevates plasma APOC3 as well as atherogenic triglyceride-rich (TG-rich) lipoproteins (TRLs). Using two mouse models of T1DM, the authors investigated APOC3-mediated inhibition of both TG hydrolysis by lipoprotein lipase and hepatic uptake of remnant lipoproteins. They suggest that poorly catabolized lipoproteins, enriched in both APOC3 and APOE content, are particularly atherogenic. Notably, treating both mouse models with an APOC3 antisense oligonucleotide lowered both plasma APOC3 and TRLs, and prevented atherosclerosis. These impactful mouse studies were supported by the initial finding that APOC3 predicted coronary artery disease events in participants of the prospective Coronary Artery Calcification in Type 1 Diabetes study with normal TG levels.

Mechanism of YLTZ on glycolipid metabolism based on UPLC/TOF/MS metabolomics

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by dysfunction of glycolipid metabolism. YLTZ is used to treat hyperlipidemia, yet its hypolipidemic and hypoglycemic mechanism on T2DM are unknown. Thus, UPLC/TOF/MS was applied in this study to identify the potential bio-markers, and deduce the possible metabolic pathways. According to bio-indexes, the increased blood lipid levels, including TC, TG, LDL and FA, and the decreased HDL, the elevated glucose, reduced insulin level and impaired OGTT were observed in diabetic rat model. While YLTZ can decrease the lipid levels and glucose content, as well as increased insulin standards and improve OGTT. After data from UPLC/TOF/MS processed, 17 metabolites were obtained, including phospholipids (LPCs, PCs and PGP (18:1)), beta-oxidation production (HAA, VAG and CNE) and precursors (THA), bile acid (CA, CDCA and IDCA), hydrolysate of TG (MG (22:4)), glycometabolism (G6P), cholesterol-driven synthetics (ADO) and production of arachidonate acid (THETA). As a result, YLTZ was able to reduce LPCs, PCs, PGP (18:1), HAA, VAG, CNE, CA, ADO and THETA, as well as enhance MG (22:4) and G6P. After analyzing results, several metabolic pathways were deduced, which containing, cholesterol synthesis and elimination, FA beta-oxidation, TG hydrolysis, phospholipids synthesis, glycolysis, gluconeogenesis and inflammation. Consequently, YLTZ performed to prohibit the FA beta-oxidation, synthesis of cholesterol and phospholipids, gluconeogenesis and inflammation level, as well as promote TG hydrolysis, glycolysis and blood circulation. Hence, applying metabonomics in TCM research can uncover its pharmacological edges, elucidating comprehensively that YLTZ has capacity of hypolipidemic, hypoglycemic and promoting blood circulation, matching the effect of removing blood stasis, eliminating phlegm and dampness.

MTOR signaling in adipose tissue influences systemic lipid metabolism

Rapamycin, a fungicidal macrolide, has been shown to increase life span and delay the onset of age related diseases across several model organisms. However, rapamycin treatment leads to metabolic dysregulation including glucose intolerance and hyperlipidemia, which limits its potential utility as an anti‐ageing agent. Rapamycin treatment increases serum triglycerides in human patients by 95%, and while it influences the expression of multiple proteins involved in lipid handling in liver and adipose tissue, the precise mechanism by which rapamycin treatment causes hypertriglyceridemia is not knownRapamycin is an allosteric inhibitor of mTOR (mechanistic target of rapamycin), a serine/threonine protein kinase that functions as a master regulator of cellular growth and metabolism. mTOR exists in two distinct protein complexes, mTORC1 (characterized by the presence of raptor) and mTORC2 (characterized by the presence of rictor), with each complex phosphorylating a distinct set of effector proteins. Rapamycin acutely inhibits mechanistic target of rapamycin complex I (mTORC1), but can also inhibit mTORC2 under chronic conditions. Tissue specific disruption of mTORC1 or mTORC2 has revealed that each complex has different effects on whole body glucose and lipid homeostasis in different organs. Genetic ablation of either mTORC1 or mTORC2 in hepatocytes fails to phenocopy the effects of rapamycin treatment, suggesting that mTOR signaling in another tissue is responsible for rapamycin‐induced hypertriglyceridemia.LPL hydrolyzes the TG in VLDL into FFA for uptake into adipose tissue. In addition, mTORC1 has been shown to inhibit lipolysis and therefore the releases of FFA into plasma. Using adipose specific raptor knockout mice, we show that TG clearance is delayed and LPL gene expression and genes related to LPL processing are altered in the absence of mTORC1 signaling. The decrease in TG clearance can be a result of the decrease in adipose tissue LPL synthesis due to decreased mRNA and/or decreases secretion of active LPL into the blood. This can result in decreased rate of VLDL‐TG hydrolysis and slower clearance of plasma TG, leading to a buildup of TG levels in the blood. In addition, upon refeeding, these KO mice have increased serum TG and FFA, suggesting a failure to suppress lipolysis. Based off phosphoproteomics analysis, phosphorylation of ATGL, the rate limiting enzyme in lipolysis, is increased with loss of mTORC1 in adipose tissue, thus increasing activity of ATGL. ATGL‐Raptor double knockout mice were generated. The DKO mice, upon refeeding, phenocopy control mice serum TG and FFA. This suggest that with loss of mTORC1 there is an increase in lipolysis in adipose tissue when lipolysis should be inhibited, which leads to increased release of FFA and uptake into the liver. This increase leads to an increase in liver TG for increased VLDL‐TG secretion. Decreased LPL activity and increased lipolysis in adipose can both increase plasma TG levels. We hypothesize that inhibition of mTORC1 signaling in adipose tissue is the major driver of hyperlipidemia caused by rapamycin.Support or Funding InformationThis work was supported by grants from the National Institutes of Health (R01‐AG‐043483 and R01‐DK‐098656 to J.A.B.)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Regulation of plasma lipid homeostasis by hepatic lipoprotein lipase in adult mice

LPL is a pivotal rate-limiting enzyme to catalyze the hydrolysis of TG in circulation, and plays a critical role in regulating lipid metabolism. However, little attention has been paid to LPL in the adult liver due to its relatively low expression. Here we show that endogenous hepatic LPL plays an important physiological role in plasma lipid homeostasis in adult mice. We generated a mouse model with the Lpl gene specifically ablated in hepatocytes with the Cre/LoxP approach, and found that specific deletion of hepatic Lpl resulted in a significant decrease in plasma LPL contents and activity. As a result, the postprandial TG clearance was markedly impaired, and plasma TG and cholesterol levels were significantly elevated. However, deficiency of hepatic Lpl did not change the liver TG and cholesterol contents or glucose homeostasis. Taken together, our study reveals that hepatic LPL is involved in the regulation of plasma LPL activity and lipid homeostasis.

DIFFERENCES IN PHYLOGENETIC FACTORS OF ETIOLOGY AND PATHOGENESIS UNITY OF METABOLIC PANDEMIAS - CIVILIZATION DISEASES

Regulation of metabolism in vivo can be understood when considering the formation in phylogenesis of the function of humoral, hormonal mediators, vegetative regulators separately: a) at the cell level; b) in paracrinally regulated cell communities (PC), organs and systems and c) at the body level. Each of regulation levels was formed at different stages of phylogenesis; the completion of levels occurred, we suppose, when reaching “relative biological perfection”. Formation of organs and organ systems was finished also, in our opinion, at the level of this perfection. When three levels reached sequentially were analyzed in Homo sapiens , it was revealed with systemic approach that through “relative biological perfection” at the level of the body, “regular mismatch” of metabolism is observed. Phylogenetic mismatch of the regulation of metabolism at three levels of “relative biological perfection” are etiological factors of “metabolic pandemias” of each of “civilization diseases”. All “metabolic pandemias” including atherosclerosis, metabolic arterial hypertension, IR status, obesity, metabolic syndrome and nonalcoholic fatty liver disease are disorders of one, late in phylogenesis, biological function of locomotion. Etiological basis for metabolic (essential) arterial hypertension is a regular mismatch: a local compensation of disturbances of the biological response metabolism ↔ microcirculation in the distal arterial bed with endothelium-dependent vasodilatation and only systemic compensation at the level of the body in the proximal part. For millions of years, there coexist two functionally connected and phylogenetically separated pools of fatty cells: the earlier visceral fatty cells (VFC) and the later subcutaneous adipocytes. Insulin blocks TG hydrolysis and release of nonetherified fatty acids (NEFA) into the blood plasma only from adipocytes; hormone cannot block lipolysis in phylogenetically early VFC and inhibit the effect of phylogenetically early hormones on them. Increase in blood plasma NEFA in the course of biological response of stress in vivo does not accompany proportional growth in albumin concentration. The function of phylogenetically early resident macrophages and monocytes ↔ macrophages, differentiated in intima of arteries in situ and ex tempore , is not identical. Biological response of fatty cells deposit into adipocytes occurs in the form of nonpolar triglycerides in lipoprotein composition, but their release - only in the form of polar NEFA.

Xanthine-based KMUP-1 improves HDL via PPARγ/SR-B1, LDL via LDLRs, and HSL via PKA/PKG for hepatic fat loss

The phosphodiesterase inhibitor (PDEI)/eNOS enhancer KMUP-1, targeting G-protein coupled receptors (GPCRs), improves dyslipidemia. We compared its lipid-lowering effects with simvastatin and explored hormone-sensitive lipase (HSL) translocation in hepatic fat loss. KMUP-1 HCl (1, 2.5, and 5 mg/kg/day) and simvastatin (5 mg/kg/day) were administered in C57BL/6J male mice fed a high-fat diet (HFD) by gavage for 8 weeks. KMUP-1 inhibited HFD-induced plasma/liver TG, total cholesterol, and LDL; increased HDL/3-hydroxy-3-methylglutaryl-CoA reductase (HMGR)/Rho kinase II (ROCK II)/PPARγ/ABCA1; and decreased liver and body weight. KMUP-1 HCl in drinking water (2.5 mg/200 ml tap water) for 1–14 or 8–14 weeks decreased HFD-induced liver and body weight and scavenger receptor class B type I expression and increased protein kinase A (PKA)/PKG/LDLRs/HSL expression and immunoreactivity. In HepG2 cells incubated with serum or exogenous mevalonate, KMUP-1 (10−7∼10−5 M) reversed HMGR expression by feedback regulation, colocalized expression of ABCA1/apolipoprotein A-I/LXRα/PPARγ, and reduced exogenous geranylgeranyl pyrophosphate/farnesyl pyrophosphate (FPP)-induced RhoA/ROCK II expression. A guanosine 3′,5′-cyclic monophosphate (cGMP) antagonist reversed KMUP-1-induced ROCK II reduction, indicating cGMP/eNOS involvement. KMUP-1 inceased PKG and LDLRs surrounded by LDL and restored oxidized LDL-induced PKA expresion. Unlike simvastatin, KMUP-1 could not inhibit 14C mevalonate formation. KMUP-1 could, but simvastatin could not, decrease ROCK II expression by exogenous FPP/CGPP. KMUP-1 improves HDL via PPARγ/LXRα/ABCA1/Apo-I expression and increases LDLRs/PKA/PKG/HSL expression and immunoreactivity, leading to TG hydrolysis to lower hepatic fat and body weight.

Cholesterol trafficking-related serum lipoprotein functions in children with cholesteryl ester storage disease

ObjectiveSerum lipoproteins influence cell cholesterol content by delivering and removing cholesterol to/from cells, functions mainly exerted by LDL and HDL, respectively. Especially in the case of HDL, structure and composition are crucial for function, beyond serum levels. Cholesteryl ester storage disease (CESD) is caused by LIPA gene mutations and reduced activity of lysosomal acid lipase (LAL), the enzyme responsible for hydrolysis of cholesteryl esters and TG. CESD patients typically present dyslipidaemia, liver damage and premature atherosclerosis. The objective of this work was to evaluate serum HDL cholesterol efflux capacity (CEC) and serum cholesterol loading capacity (CLC) in CESD pediatric patients and to study lipoprotein qualitative modifications. MethodsHDL CEC was evaluated by radioisotopic techniques, serum CLC was measured by a fluorimetric assay, HDL subclasses were determined by two-dimensional electrophoresis. ResultsCESD patients (n = 3) displayed on average increased LDL cholesterol (+163%; p = 0.019), TG (+203; p = 0.012), phospholipids (+40%; p = 0.024) and lower HDL cholesterol (−57%; p = 0.012) compared to controls (n = 9). CESD HDL CEC was impaired both as a whole (average reduction of 26%; p < 0.0001) and with respect to specific membrane cholesterol transporters (−23% for aqueous diffusion; p = 0.005; −32% for ABCA1-efflux; p = 0.0002; −60% for SR-BI-efflux; p < 0.0001; −42% for ABCG1-efflux p = 0.0003). A marked reduction in the pre-β HDL concentration (−69%; p = 0.012) was detected. Finally, CESD serum CLC was significantly increased (+21%; p = 0.0007). Conclusion: These new data demonstrate that the pro-atherogenic modifications of serum include disturbances in lipoprotein functions involved in cell cholesterol homeostasis occurring from very early age in CESD patients.

Adipose triglyceride lipase regulates eicosanoid production in activated human mast cells

Human mast cells (MCs) contain TG-rich cytoplasmic lipid droplets (LDs) with high arachidonic acid (AA) content. Here, we investigated the functional role of adipose TG lipase (ATGL) in TG hydrolysis and the ensuing release of AA as substrate for eicosanoid generation by activated human primary MCs in culture. Silencing of ATGL in MCs by siRNAs induced the accumulation of neutral lipids in LDs. IgE-dependent activation of MCs triggered the secretion of the two major eicosanoids, prostaglandin D2 (PGD2) and leukotriene C4 (LTC4). The immediate release of PGD2 from the activated MCs was solely dependent on cyclooxygenase (COX) 1, while during the delayed phase of lipid mediator production, the inducible COX-2 also contributed to its release. Importantly, when ATGL-silenced MCs were activated, the secretion of both PGD2 and LTC4 was significantly reduced. Interestingly, the inhibitory effect on the release of LTC4 was even more pronounced in ATGL-silenced MCs than in cytosolic phospholipase A2-silenced MCs. These data show that ATGL hydrolyzes AA-containing TGs present in human MC LDs and define ATGL as a novel regulator of the substrate availability of AA for eicosanoid generation upon MC activation.

Coupling of lipolysis and de novo lipogenesis in brown, beige, and white adipose tissues during chronic β3-adrenergic receptor activation

Chronic activation of β3-adrenergic receptors (β3-ARs) expands the catabolic activity of both brown and white adipose tissue by engaging uncoupling protein 1 (UCP1)-dependent and UCP1-independent processes. The present work examined de novo lipogenesis (DNL) and TG/glycerol dynamics in classic brown, subcutaneous "beige," and classic white adipose tissues during sustained β3-AR activation by CL 316,243 (CL) and also addressed the contribution of TG hydrolysis to these dynamics. CL treatment for 7 days dramatically increased DNL and TG turnover similarly in all adipose depots, despite great differences in UCP1 abundance. Increased lipid turnover was accompanied by the simultaneous upregulation of genes involved in FAS, glycerol metabolism, and FA oxidation. Inducible, adipocyte-specific deletion of adipose TG lipase (ATGL), the rate-limiting enzyme for lipolysis, demonstrates that TG hydrolysis is required for CL-induced increases in DNL, TG turnover, and mitochondrial electron transport in all depots. Interestingly, the effect of ATGL deletion on induction of specific genes involved in FA oxidation and synthesis varied among fat depots. Overall, these studies indicate that FAS and FA oxidation are tightly coupled in adipose tissues during chronic adrenergic activation, and this effect critically depends on the activity of adipocyte ATGL.

Hepatic ATGL mediates PPAR-α signaling and fatty acid channeling through an L-FABP independent mechanism

Adipose TG lipase (ATGL) catalyzes the rate-limiting step in TG hydrolysis in most tissues. We have shown that hepatic ATGL preferentially channels hydrolyzed FAs to β-oxidation and induces PPAR-α signaling. Previous studies have suggested that liver FA binding protein (L-FABP) transports FAs from lipid droplets to the nucleus for ligand delivery and to the mitochondria for β-oxidation. To determine if L-FABP is involved in ATGL-mediated FA channeling, we used adenovirus-mediated suppression or overexpression of hepatic ATGL in either WT or L-FABP KO mice. Hepatic ATGL knockdown increased liver weight and TG content of overnight fasted mice regardless of genotype. L-FABP deletion did not impair the effects of ATGL overexpression on the oxidation of hydrolyzed FAs in primary hepatocyte cultures or on serum β-hydroxybutyrate concentrations in vivo. Moreover, L-FABP deletion did not influence the effects of ATGL knockdown or overexpression on PPAR-α target gene expression. Taken together, we conclude that L-FABP is not required to channel ATGL-hydrolyzed FAs to mitochondria for β-oxidation or the nucleus for PPAR-α regulation.

Abstract 632: Lipoprotein Lipase Activators: A New Potent Drug Class for Treatment of Dyslipidemia

Aim: Elevated plasma TG and low HDL-cholesterol are part of CVD residual risk. Lipoprotein lipase (LPL) is the central enzyme controlling plasma TG hydrolysis and affecting de novo HDL formation. Thus LPL is an attractive target for correcting dyslipidemia and reduction of CVD residual risk. We have identified a novel first-in-class small molecule LPL activator - LP071. The objective with this study was to characterize the plasma lipid metabolism in LPL activator treated mice. Methods: ApoE3L:CETP mice were treated week with LP071. Plasma lipid profiles were analyzed using FPLC fractioning. LPL activity was investigated systemically and in specific tissue. Using triton WR1339 blockade chylomicron and VLDL secretion were assessed. Functional lipid clearance test were performed by oral fat tolerance tests. Results: Fasting plasma TG levels decreased with 97 % in apoE3L:CETP mice treated with LP071; HDL-c were increased by 116 % and (V)LDL-c were decreased with 91 %. Plasma free glycerol and NEFA were significantly lowered, 26 % and 22 % respectively. After an oral lipid load the plasma lipid response was significantly blunted in LP071 treated mice compared to controls. LPL activity in subcutaneous adipose tissue was increased 1500 % and in BAT LPL was increased by 100% at 3 h after a lipid gavage in WT mice treated with LP071. Conclusions: LP071 is a potent compound that can improve plasma lipid levels to a less atherogenic profile. The LP-class LPL activators can potentially help battle CVD residual risk in the future.

Novel Aspects of Nonfasting Lipemia in relation to Vascular Biology

Several cardiovascular risk factors have been described during the last decades. Postprandial hyperlipidemia has been recognized as an important factor contributing to atherogenesis; however chylomicron remnants have not been used widely in risk equations. One of the probable causes for this lack of consideration in clinical practice may be that the metabolism of chylomicrons and their remnants has been rather difficult to study and, more so, to modulate in vivo. The current issue of the International Journal of Vascular Medicine provides novel insight into the metabolic changes of chylomicrons and their remnants in relation to vascular damage. The paper by G. H. Tomkin and D. Owens “The chylomicron: relationship to atherosclerosis” provides an excellent overview of the molecular mechanisms involved in chylomicron synthesis and metabolism in humans. The paper by B. Klop et al. “Understanding postprandial inflammation and its relationship to lifestyle behaviour and metabolic diseases” describes novel aspects related to inflammation in different clinical conditions and under variable lifestyle situations. Following this line of inflammatory-dependent aspects of chylomicrons, the paper by M. Cao et al. “Dual AAV/IL-10 plus STAT3 anti-inflammatory gene delivery lowers atherosclerosis in LDLR KO mice, but without increased benefit” further explores aspects of cholesterol metabolism involving different molecular targets important for both hepatic and intestinal cholesterol metabolism. S. A. Lopez et al. proceed with a paper investigating the effects of oxidized chylomicron remnants on monocyte activation and the effects of the antioxidant drug probucol on this interaction “The oxidative state of chylomicron remnants influences their modulation of human monocyte activation.” L. D. Roche and et al. provide evidence suggesting that postprandial hypertriglyceridemia simulated by an infusion with artificial TG-rich lipoproteins (Lipofundin) induces oxidative stress and atherosclerotic lesions in an animal model prone to develop atherosclerosis “Lipofundin-induced hyperlipidemia promotes oxidative stress and atherosclerotic lesions in New Zealand white rabbits.” The paper by M. Napolitano et al. “Phospholipase A2 mediates apolipoprotein-independent uptake of chylomicron remnant-like particles by human macrophages” includes novel work showing that macrophage lipolytic enzymes mediate the internalization of postprandial TG-rich lipoproteins and that secretory phospholipase A2 (sPLA2) and cytosolic PLA2 play a more important role than extracellular lipoprotein lipase-mediated TG hydrolysis. M. M. Pallebage-Gamarallage et al. describe in the following investigation “A diet enriched in docosahexanoic acid exacerbates brain parenchymal extravasation of Apo B lipoproteins induced by chronic ingestion of saturated fats,” how dietary interventions can lead to modulation of cerebrovascular inflammation by oxidative stress. A. Van der Wiel provides a comprehensive update on the effects of alcohol ingestion on fasting and postprandial triglyceridemia “The effect of alcohol on postprandial and fasting triglycerides”, which is followed by a paper by B. Klop et al. “AT1 receptor gene polymorphisms in relation to postprandial lipemia” showing a novel relationship between polymorphisms of genes involved in the regulation of blood pressure with postprandial lipemia. J. P. H. van Wijk and M. Castro Cabezas contributed with an update on the effects of antiretroviral therapy in HIV-infected patients on TG metabolism “Hypertriglyceridemia, metabolic syndrome, and cardiovascular disease in HIV-infected patients: effects of antiretroviral therapy and adipose tissue distribution.” Finally, G. Charach et al. provided a review describing the effects of bile acid secretion and intestinal absorption on plasma lipoproteins and coronary atherosclerosis. M. Castro Cabezas Kathleen M. Botham John C. L. Mamo Spencer D. Proctor

CETP expression reverses the reconstituted HDL-induced increase in VLDL

Human data suggest that reconstituted HDL (rHDL) infusion can induce atherosclerosis regression. Studies in mice indicated that rHDL infusion adversely affects VLDL levels, but this effect is less apparent in humans. This discrepancy may be explained by the fact that humans, in contrast to mice, express cholesteryl ester transfer protein (CETP). The aim of this study was to investigate the role of CETP in the effects of rHDL on VLDL metabolism by using APOE*3-Leiden (E3L) mice, a well-established model for human-like lipoprotein metabolism. At 1 h after injection, rHDL increased plasma VLDL-C and TG in E3L mice, but not in E3L mice cross-bred onto a human CETP background (E3L.CETP mice). This initial raise in VLDL, caused by competition between rHDL and VLDL for LPL-mediated TG hydrolysis, was thus prevented by CETP. At 24 h after injection, rHDL caused a second increase in VLDL-C and TG in E3L mice, whereas rHDL had even decreased VLDL in E3L.CETP mice. This secondary raise in VLDL was due to increased hepatic VLDL-TG production. Collectively, we conclude that CETP protects against the rHDL-induced increase in VLDL. We anticipate that studies evaluating the anti-atherosclerotic efficacy of rHDL in mice that are naturally deficient for CETP should be interpreted with caution, and that treatment of atherogenic dyslipidemia by rHDL should not be combined with agents that aggressively reduce CETP activity.

Multidirectional time-dependent effect of sinigrin and allyl isothiocyanate on metabolic parameters in rats.

Sinigrin (SIN) and allyl isothiocyanate (AITC) are compounds found in high concentrations in Brassica family vegetables, especially in Brussels sprouts. Recently, they have been used as a nutrition supplement for their preventive and medicinal effect on some types of cancer and other diseases. In this research, nutritional significance of parent glucosinolate sinigrin 50 μmol/kg b. w./day and its degradation product allyl isothiocyanate 25 μmol/kg b. w./day and 50 μmol/kg b. w./day was studied by the evaluation of their influence on some parameters of carbohydrate and lipid metabolism in an animal rat model in vivo after their single (4 h) and 2 weeks oral administration. Additionally, the aim of this trial was to evaluate the direct action of AITC on basal and epinephrine-induced lipolysis in isolated rat adipocytes at concentration 1 μM, 10 μM and 100 μM in vitro. Sole AITC after 4 h of its ingestion caused liver triacylglycerols increment at both doses and glycaemia only at the higher dose. Multiple SIN treatment showed its putative bioconversion into AITC. It was found that SIN and AITC multiple administration in the same way strongly disturbed lipid and carbohydrate homeostasis, increasing esterified and total cholesterol, free fatty acids and lowering tracylglycerols in the blood serum. Additionally, AITC at both doses elevated insulinaemia and liver glycogen enhancement. The in vitro experiment revealed that AITC potentiated basal lipolysis process at 10 μM, and had stimulatory effect on epinephrine action at 1 μM and 10 μM. The results of this study demonstrated that the effect of SIN and AITC is multidirectional, indicating its impact on many organs like liver as well as pancreas, intestine in vivo action and rat adipocytes in vitro. Whilst consumption of cruciferous vegetables at levels currently considered “normal” seems to be beneficial to human health, this data suggest that any large increase in intake could conceivably lead to undesirable effect. This effect is potentiated with time of action of the examined compounds, whose influence is rather adverse for the majority of metabolic pathways (liver steatosis at short duration and insulinaemia, cholesterolaemia at long time treatment). Beneficial action of AITC concerned intensified hydrolysis of TG in the blood serum with a simultaneous lipolysis in adipocytes.

P260 CETP EXPRESSION REVERSES THE RECONSTITUTED HDL-INDUCED INCREASE IN VLDL

Human data suggest that reconstituted HDL (rHDL) infusion can induce atherosclerosis regression. Studies in mice indicated that rHDL infusion adversely affects VLDL levels, but this effect is less apparent in humans. This discrepancy may be explained by the fact that humans, in contrast to mice, express cholesteryl ester transfer protein (CETP). The aim of this study was to investigate the role of CETP in the effects of rHDL on VLDL metabolism by using APOE*3-Leiden (E3L) mice, a well-established model for human-like lipoprotein metabolism. At 1 h after injection, rHDL increased plasma VLDL-C and TG in E3L mice, but not in E3L mice cross-bred onto a human CETP background (E3L.CETP mice). This initial raise in VLDL, caused by competition between rHDL and VLDL for LPLmediated TG hydrolysis, was thus prevented by CETP. At 24 h after injection, rHDL caused a second increase in VLDL-C and TG in E3L mice, whereas rHDL had even decreased VLDL in E3L.CETP mice. This secondary raise in VLDL was due to increased hepatic VLDL-TG production. Collectively, we conclude that CETP protects against the rHDL-induced increase in VLDL. We anticipate that studies evaluating the anti-atherosclerotic efficacy of rHDL in mice that are naturally deficient for CETP should be interpreted with caution, and that treatment of atherogenic dyslipidemia by rHDL should not be combined with agents that aggressively reduce CETP activity. Copyright © 2011 by the American Society for Biochemistry and Molecular Biology, Inc.