Lipoprotein Lipase Levels Research Articles

Abstract 246: Global Analysis of Differentially Expressed Genes in the Aortae of Apoe-deficient Mice Infused with Insulin-like Growth Factor I: Novel Mechanisms of the Anti-atherogenic Effect of IGF-1

We have previously shown that insulin like growth factor-I (IGF-1) suppresses atherosclerosis progression in ApoE-null mice. To determine mechanisms, ApoE-null mice were chronically infused with IGF-1 (1.5 mg/kg/d, 12 weeks) or saline (control) or treated short-term with IGF-1 (0.4 mg/kg/d, i.p., 1 week) or saline (control). Aortic gene expression of 84 atherosclerosis-related genes-of-interest was analyzed with RT-PCR arrays. Chronic IGF-1 infusion decreased expression levels of pro-apoptotic molecules (Bax, 0.62, BID, 0.26), adhesion molecules (integrin β2, 0.32, integrin α2, 0.28, VCAM-1, 0.43), pro-inflammatory cytokines (TNFα, 0.22, interferon γ, 0.30) and lipoprotein lipase (LPL, an enzyme mediating lipid hydrolysis and tissue uptake of oxidized low density lipoprotein (OxLDL), 0.69). These changes in gene expression correlated with a reduction in atherosclerotic plaque burden (Oil Red-positive aortic valve lesion area, ×000 pixels 2 , IGF-1, 228±13, saline, 268±22), suppression of plaque apoptosis (% apoptotic cells per plaque, IGF-1, 3.4±0.7, saline, 5.8±0.5, P<0.05, TUNEL assay), decrease in plaque TNFα levels (58% reduction vs. saline, P<0.05, immunostaining), and inhibition of serum LPL activity (IGF-1, 1.1±0.2, saline, 3.7±0.4, P<0.05, fluorescence assay). Short-term IGF-1 treatment similarly decreased mRNA levels of Bax (0.68), BID (0.61), integrin β2 (0.62), TNFα (0.50), interferon γ (0.37), LPL (0.42) and also downregulated a group of scavenger receptors (CD36, 0.44, MSR-1, 0.48, MSR-2, 0.52). To further characterize the effect of IGF-1 on LPL we exposed THP-1-derived macrophages to OxLDL (80 ug/ml, 16 h) in the presence or absence of IGF-1. OxLDL increased LPL activity in conditioned media (>5 fold, P<0.01), but pre-treatment with IGF-1 (25 ng/ml, 24 h) reversed LPL upregulation by 52% and suppressed lipid internalization by 88% (P<0.05, Oil Red staining). In summary IGF-1 reduces pro-inflammatory cytokines, pro-apoptotic molecules, adhesion molecules, scavenger receptors, and lipoprotein lipase expression in ApoE-null mice and markedly blunts OxLDL-induced upregulation of LPL and lipid uptake in THP-derived macrophages. These data provide major insights into mechanisms whereby IGF-1 is atheroprotective.

Dietary single cell protein reduces fatty liver in obese Zucker rats

There is growing evidence that dietary proteins may interfere with lipid metabolism. We therefore examined the effects of feeding obese Zucker rats a single cell protein (SCP) with low ratios of methionine:glycine and lysine:arginine for 6 weeks. SCP feeding reduced the hepatic steatosis and lowered the plasma transaminase levels when compared with casein-fed rats (controls). The fatty acid oxidation was increased in liver mitochondria and peroxisomes, whereas the activities of enzymes involved in lipogenesis and TAG biosynthesis were unaffected. SCP feeding affected the fatty acid composition of liver lipids and plasma, and reduced the mRNA levels of the fatty acid desaturases. The decreased gene expression of stearoyl-CoA desaturase suggested that the fatty acids were directed towards oxidation rather than esterification as TAG. The decreased mRNA levels of VLDL-receptor and lipoprotein lipase in the liver after SCP feeding suggested that the uptake of TAG-rich lipoprotein to the liver was decreased. To conclude, the reduced fatty liver by SCP feeding may be caused by the increased capacity for fatty acid beta-oxidation in the liver, combined with changed fatty acid composition and possibly a reduced hepatic clearance of circulating VLDL. An increased awareness of the effect of dietary proteins on lipid metabolism could be of relevance in future dietary treatment of non-alcoholic fatty liver disease.

Transthyretin knockout mouse nerves have increased lipoprotein lipase and sphingolipid content following crush

Transthyretin (TTR) knockout (KO) mice display increased levels of lipoprotein lipase (LPL) and impaired nerve regeneration. Given LPL potential role in the reutilization of myelin lipids following injury, we compared myelin lipid content in wild-type and TTR KO mice after nerve crush. We found that LPL is expressed not only in Schwann cells but also in dorsal root ganglia neurons and that its activity is increased in TTR KO mice following nerve injury. As a possible consequence of LPL increase in the regenerating nerve of TTR KOs, the sphingolipids sphingomyelin and galactocerebroside were augmented in the distal nerve stump. Given their ability to increase neurite outgrowth, upregulation of LPL and sphingolipids in a system with decreased capacity for nerve regeneration probably constitutes a compensatory mechanism.

Miglitol suppresses the postprandial increase in interleukin 6 and enhances active glucagon-like peptide 1 secretion in viscerally obese subjects

Visceral obesity and insulin resistance are regarded as risk factors for atherosclerosis. Epidemiologic studies have demonstrated long-term anti-atherosclerotic effects with administration of α-glucosidase inhibitors. α-Glucosidase inhibitors also have been reported to enhance glucagon-like peptide 1 (GLP-1) secretion. We compared the postprandial effects of a single administration of miglitol and acarbose on glucose and lipid metabolism, on insulin requirement, on GLP-1 secretion, and on inflammatory and endothelial markers in viscerally obese subjects. Twenty-four viscerally obese subjects with relative insulin resistance participated in this study. Subjects were given a single dose of miglitol (50 mg), acarbose (100 mg), or placebo blindly and randomly before a meal in a crossover design. The meal loads after drug administration were tested 3 times within 2 weeks. We measured glucose, insulin, lipids, lipoprotein lipase, interleukin 6, intracellular adhesion molecule 1, vascular cell adhesion molecule 1, and active GLP-1 at before and various minutes after the meal. Single administration of both α-glucosidase inhibitors had several beneficial effects in improving postprandial hyperglycemia and reducing postprandial insulin requirement approximately 25% of placebo without adversely affecting lipid profiles. Although lipoprotein lipase levels within 2 hours after the meal did not show differences among miglitol, acarbose, and placebo administrations, miglitol significantly suppressed the increases in triglycerides, remnant-like particle triglycerides, and remnant-like particle cholesterol compared to acarbose and placebo in the early phase. Miglitol also significantly enhanced active GLP-1 secretion to a greater extent than acarbose ( P < .01) and placebo ( P < .001), and significantly suppressed the postprandial increase in interleukin 6 compared to placebo ( P < .01). The results point to the potential suitability of miglitol as an anti-atherosclerotic effect in viscerally obese subjects, in preference to acarbose. Further studies are needed to elucidate the long-term effects on enhanced GLP-1 secretion and anti-atherosclerosis.

Expression level of lipoprotein lipase in patients with chronic lymphocytic leukemia and its correlation with other prognostic factors

18000 Background: Chronic lymphocytic leukemia (CLL) is the most common adult form of leukemia in the Western world, however, infrequent in the Eastern. It shows a remarkable heterogeneity, with some patients having an almost normal lifespan, others surviving only several years after diagnosis despite intensive therapy. A series of recent microarray studies have identified a number of other potential prognostic factors that have not yet been validated for their clinical importance. One of the genes most closely related to IgVH mutational status is lipoprotein lipase (LPL). Methods: To investigate LPL expression level in Chinese patients with CLL and its correlation with other prognostic factors, including IgVH mutation status, Binet stages, ZAP-70 protein and CD38 expression level, semiquantitative RT-PCR was used to detect LPL expression in peripheral blood samples of 58 Chinese patients with CLL. IgVH somatic mutational status was detected by multiplex PCR and sequencing of purified PCR amplification pr...

A Developmental Model of Sarcomagenesis Defines a Differentiation-Based Classification for Liposarcomas

The importance of adult stem cells in the development of neoplastic diseases is becoming increasingly well appreciated. We hypothesized that sarcomas of soft tissue could be categorized by their developmental/differentiation status from stem cell to mature tissue, similar to the hematological malignancies. We conducted gene expression analyses during in vitro differentiation of human mesenchymal stem cells into adipose tissue, as a representative mature connective tissue, and identified genes whose expression changed significantly during adipogenesis. Gene clustering and distance correlation analysis allowed the assignment of a unique time point during adipogenesis that strongly correlates to each of the four major liposarcoma subtypes. Using a novel gene expression strategy, in which liposarcomas are compared to their corresponding adipocytic maturing cells, we identified a group of genes overexpressed in liposarcomas that indicate the stage of differentiation arrest, ie, sharing a similar expression profile to adipocytic cells at a corresponding stage of differentiation, and a distinct set of genes overexpressed in liposarcomas that are not found in the corresponding stage of differentiation. We propose that the latter set is enriched for candidate transformation-associated genes. Our results indicate that a degree of developmental maturity can be quantitatively assigned to solid tumors, supporting the notion that transformation of a solid tumor stem cell can occur at distinct stages of maturation.

Adiponectin Reduces Plasma Triglyceride by Increasing VLDL Triglyceride Catabolism

OBJECTIVE—Adiponectin is an adipocyte-derived hormone that plays an important role in glucose and lipid metabolism. The main aims of this study are to investigate the effects of adiponectin on VLDL triglyceride (VLDL-TG) metabolism and the underlying mechanism.RESEARCH DESIGN AND METHODS—Adenoviruses were used to generate a mouse model with elevated circulating adiponectin. HepG2 and C2C12 cells were treated with recombinant human adiponectin.RESULTS—Three days after Ad-mACRP30 adenovirus injection, plasma adiponectin protein levels were increased 12-fold. All three main multimeric adiponectin molecules were proportionally elevated. Fasting plasma TG levels were significantly decreased (∼40%) in the mice with elevated adiponectin in circulation, as were the plasma levels of large and medium VLDL subclasses. Although apolipoprotein B mRNA levels were robustly suppressed in the livers of adiponectin-overexpressing mice and in cultured HepG2 cells treated with recombinant human adiponectin, hepatic VLDL-TG secretion rates were not altered by elevated plasma adiponectin. However, Ad-mACRP30–treated mice exhibited a significant increase of postheparin plasma lipoprotein lipase (LPL) activity compared with mice that received control viral vector. Skeletal muscle LPL activity and mRNA levels of LPL and VLDL receptor (VLDLr) were also increased in Ad-mACRP30–treated mice. Recombinant human adiponectin treatment increased LPL and VLDLr mRNA levels in differentiated C1C12 myotubes.CONCLUSIONS—These results suggest that adiponectin decreases plasma TG levels by increasing skeletal muscle LPL and VLDLr expression and consequently VLDL-TG catabolism.

Molecular Mechanism of Age‐Specific Hepatic Lipid Accumulation in PPARα (+/−):LDLR (+/−) Mice, an Obese Mouse Model

This study aimed to clarify the molecular mechanisms of age-specific hepatic lipid accumulation accompanying hyperinsulinemia in a peroxisome proliferator-activated receptor alpha (PPARalpha) (+/-):low-density lipoprotein receptor (LDLR) (+/-) mouse line. The hepatic fat content, protein amounts, and mRNA levels of genes involved in hepatic lipid metabolism were analyzed in 25-, 50-, 75- and 100-week-old mice. Severe fatty liver was confirmed only in 50- and 75-week-old mice. The hepatic expression of proteins that function in lipid transport and catabolism did not differ among the groups. In contrast, the mRNA levels and protein amounts of lipogenic enzymes, including acetyl-coenzyme A carboxylase-1, fatty acid synthase, and glycerol-3-phosphate acyltransferase, enhanced in the mice with fatty liver. Elevated mRNA and protein levels of lipoprotein lipase and fatty acid translocase, which are involved in hepatic lipid uptake, were also detected in mice with fatty liver. Moreover, both protein and mRNA levels of sterol regulatory element-binding protein-1 (SREBP-1), a transcription factor regulating lipid synthesis, had age-specific patterns similar to those of the proteins described above. Therefore, the age-specific fatty liver found in the PPARalpha (+/-):LDLR (+/-) mouse line is probably caused by age-specific expression of SREBP-1 and its downstream lipogenic genes, coordinated by the increased uptake of lipids. All of these factors might be affected by age-specific changes in serum insulin concentration.

Trans-10, Cis-12 Conjugated Linoleic Acid Antagonizes Ligand-Dependent PPARγ Activity in Primary Cultures of Human Adipocytes

We previously demonstrated that trans-10, cis-12 (10,12) conjugated linoleic acid (CLA) causes human adipocyte delipidation, insulin resistance, and inflammation in part by attenuating PPARγ target gene expression. We hypothesized that CLA antagonizes the activity of PPARγ in an isomer-specific manner. 10,12 CLA, but not cis-9, trans-11 (9,11) CLA, suppressed ligand-stimulated activation of a peroxisome proliferator response element-luciferase reporter. This decreased activation of PPARγ by 10,12 CLA was accompanied by an increase in PPARγ and extracellular signal-related kinase (ERK)1/2 phosphorylation, followed by decreased PPARγ protein levels. To investigate if 10,12 CLA-mediated delipidation was preventable with a PPARγ ligand (BRL), cultures were treated for 1 wk with 10,12 CLA or 10,12 CLA + BRL and adipogenic gene and protein expression, glucose uptake, and triglyceride (TG) were measured. BRL cosupplementation completely prevented 10,12 CLA suppression of adipocyte fatty acid-binding protein, lipoprotein lipase, and perilipin mRNA levels without preventing reductions in PPARγ or insulin-dependent glucose transporter 4 (GLUT4) expression, glucose uptake, or TG. Lastly, we investigated the impact of CLA withdrawal in the absence or presence of BRL for 2 wk. CLA withdrawal did not rescue CLA-mediated reductions in adipogenic gene and protein expression. In contrast, BRL supplementation for 2 wk following CLA withdrawal rescued mRNA levels of PPARγ target genes. However, the levels of PPARγ and GLUT4 protein and TG were only partially rescued by BRL. Collectively, we demonstrate for the first time, to our knowledge, that 10,12 CLA antagonizes ligand-dependent PPARγ activity, possibly via PPARγ phosphorylation by ERK.

Dysregulation of lipid metabolism in cardiac muscle of mice with cachexia

Approximately 30% of all cancer deaths are caused by cachexia, a condition of severe muscle loss and abnormal lipid metabolism. The objective of this study was to elucidate events that lead to impaired lipid metabolism and muscle wasting in cardiac muscle of mice exhibiting cancer‐induced muscle atrophy. In male CD2F1 mice injected with C26 tumor cells, body weight and mass of quadriceps, gastrocnemius and heart were significantly reduced after 18 days compared to mice injected with vehicle. In the highly oxidative cardiac muscle of mice bearing tumors, phosphorylated‐AMP dependent kinase (AMPK) was elevated. However, a rate limiting enzyme in β‐oxidation, carnitine palmitoyl transferase‐1β (CPT‐1β) mRNA expression was reduced by 40% while peroxisome proliferator‐activated receptor α (PPARα) mRNA was reduced by 35%. In contrast, mRNA levels of lipoprotein lipase (LPL) and adipose triglyceride lipase (ATGL) were induced, suggesting increased fatty acid uptake and lipolysis. Unexpectedly, uncoupling protein 2 (UCP2) mRNA was induced 5.3 fold. Activated AMPK with increased fatty acid uptake without induction of markers of β‐oxidation suggest that downstream events of AMPK are dysregulated in cachexia‐induced atrophy of cardiac muscle. Further work will determine whether induction of UCP2 alleviates reactive oxygen species (ROS) and results in thermogenesis. Supported by Cognis Corporation and OARDC.

Bitter melon (Momordica charantia L.) inhibits adipocyte hypertrophy and down regulates lipogenic gene expression in adipose tissue of diet-induced obese rats

Bitter melon (Momordica charantia; BM) has been shown to ameliorate diet-induced obesity and insulin resistance. To examine the effect of BM supplementation on cell size and lipid metabolism in adipose tissues, three groups of rats were respectively fed a high-fat diet supplemented without (HF group) or with 5 % lyophilised BM powder (HFB group), or with 0.01 % thiazolidinedione (TZD) (HFT group). A group of rats fed a low-fat diet was also included as a normal control. Hyperinsulinaemia and glucose intolerance were observed in the HF group but not in HFT and HFB groups. Although the number of large adipocytes (>180 microm) of both the HFB and HFT groups was significantly lower than that of the HF group, the adipose tissue mass, TAG content and glycerol-3-phosphate dehydrogenase activity of the HFB group were significantly lower than those of the HFT group, implying that BM might reduce lipogenesis in adipose tissue. Experiment 2 was then conducted to examine the expression of lipogenic genes in adipose tissues of rats fed low-fat, HF or HFB diets. The HFB group showed significantly lower mRNA levels of fatty acid synthase, acetyl-CoA carboxylase-1, lipoprotein lipase and adipocyte fatty acid-binding protein than the HF group (P < 0.05). These results indicate BM can reduce insulin resistance as effective as the anti-diabetic drug TZD. Furthermore, BM can suppress the visceral fat accumulation and inhibit adipocyte hypertrophy, which may be associated with markedly down regulated expressions of lipogenic genes in the adipose.

Biochemical, Pathological, and Skeletal Improvement of Mucopolysaccharidosis VI After Gene Transfer to Liver but Not to Muscle

Mucopolysaccharidosis VI (MPS VI) is caused by deficient activity of arylsulfatase B (ARSB), resulting in intralysosomal storage of dermatan sulfate (DS) and multisystem disease without central nervous system involvement. After gene transfer, muscle or liver can theoretically be converted into factories for systemic ARSB secretion, leading to uptake by non-transduced cells. We have injected newborn MPS VI rats and cats with adeno-associated viral (AAV) vectors expressing ARSB under the control of liver-specific, muscle-specific, or universally active promoters. After systemic or intramuscular (IM) administration of AAV, therapeutic levels of circulating ARSB are achieved, resulting in skeletal improvements and significant decrease in glycosaminoglycan (GAG) storage, inflammation and apoptosis (despite a neutralizing immune response to ARSB in MPS VI rats). In addition, we have observed wide-spread dissemination of vector after IM AAV administration. This results in secretion of therapeutic levels of ARSB when the universally active cytomegalovirus (CMV) but not the muscle-specific muscle creatine kinase (MCK) promoter is used, suggesting that transduction of extramuscular sites rather than enzyme secretion from muscle occurs after muscle ARSB gene transfer. We conclude that AAV-mediated expression of ARSB from liver represents a feasible therapeutic strategy for MPS VI, potentially avoiding multiple infusions of costly recombinant enzyme associated with enzyme replacement therapy.

Antidiabetic and Hypolipidemic Effects of a Novel Dual Peroxisome Proliferator-Activated Receptor (PPAR) α/γ Agonist, E3030, in db/db Mice and Beagle Dogs

We investigated the antidiabetic effects of E3030, which is a potent dual activator of peroxisome proliferator-activated receptor (PPAR) alpha and PPARgamma, in an animal model of diabetes, C57BL/KsJ-db/db mice (db/db mice), and the lipidemic effects of E3030 in beagle dogs, whose PPARalpha and PPARgamma transactivation responses to E3030 were similar to those of humans. E3030 activated human PPARalpha, mouse PPARalpha, dog PPARalpha, human PPARgamma, mouse PPARgamma, and dog PPARgamma with EC(50) values of 65, 920, 87, 34, 73, and 34 nM, respectively, in the chimeric GAL4-PPAR receptor transactivation reporter assay. In db/db mice orally administered E3030 decreased blood glucose, triglyceride (TG), non-esterified fatty acids (NEFA), and insulin levels and increased blood adiponectin levels during a 14-day experimental period. Significant effects on blood glucose and adiponectin levels were observed at a dose of 3 mg/kg or greater. Furthermore, significant effects on blood TG, NEFA, and insulin levels were observed at doses of 1 mg/kg or more. An oral glucose tolerance test (OGTT) performed on Day 15 showed that E3030 at 3 mg/kg improved glucose tolerance in this model. Fourteen days of oral treatment with E3030 at a dose of 0.03 mg/kg or greater showed remarkable TG- and non high-density lipoprotein (non-HDL) cholesterol-lowering effects in beagle dogs. These results were similar to those observed for the PPARalpha agonist fenofibrate. E3030 also reduced apo C-III levels on Days 7 and 14, and elevated lipoprotein lipase (LPL) levels on Day 15. These results indicate that the TG- and non-HDL cholesterol-lowering actions of E3030 involve combined effects on reduction of apo C-III and elevation of LPL, resulting in increased lipolysis. The experimental results in animals suggest that E3030 has potential for use in the treatment of various aspects of metabolic dysfunction in type 2 diabetes, including dyslipidemia, hyperglycemia, hyperinsulinemia, and impaired glucose disposal.

지방세포 3T3-L1에 인삼 사포닌 Re와 의이인 추출액 처리시 비만관련 유전자인 TNF-&amp;#x03B1;, lipoprotein lipase, leptin 및 resistin 발현 조절에 미치는 영향

In order to determine if the mRNA and protein expression levels of 3T3-L1 adipocytes are influenced by oriental medicines, adipocytes were treated with 100 ㎍/ml of G-Re and aqueous extract of a Coix lachrymajobi var. mayuen (AEC) every other day for 12 days, respectively. The tumor necrosis factor alpha (TNF-α). mRNA and protein expressions were suppressed markedly in treated mature adipocytes. Those of lipoprotein lipase (LPL) levels were found to increase gradually in preadipocytes differentiating into mature adipocytes. Those were higher than that of the untreated mature adipocytes. The treated adipocytes showed reduction of leptin expression levels, while in untreated mature adipocytes cell, those of levels were significantly higher after the conversion of preadipocytes into mature adipocytes. The resistin levels in the treated adipocytes were significantly decreased comparing to that of the untreated mature adipocytes. In conclusion, the expression levels of LPL, TNF-α, leptin and resistin mRNA and proteins are shown to be regulated by G-Re and AEC, making them potential candidates for controlling fat mass related obesity.

Apolipoprotein E (APOE) Genotype as a Determinant of Survival in Women with Chronic Lymphocytic Leukemia.

Survival of CLL cells requires sustained activation of the anti-apoptotic PI-3-kinase/Akt pathway, and many therapies for CLL cause leukemia cell death by triggering apoptosis. Blood lipoprotein particles are either pro- or anti-apoptotic. High density lipoprotein (HDL) particles are anti-apoptotic through sphingosine-1-phosphate receptor 3 (S1P3)-mediated activation of the PI-3-K/Akt pathway. We have noted that apoE4-very low density lipoprotein (VLDL) (but not apoE2- or apoE3-VLDL) particles increase apoptosis of endothelial cells by recruiting the phosphoinositol phosphatase SHIP-2 to the plasma membrane, thereby directly inhibiting the anti-apoptotic activity of HDL (DeKroon R, et al., Circ Res 99:829–836, 2006). Since apoE4-VLDL increases apoptosis of certain cells, and since increased leukemia cell apoptosis favors longer survival in CLL, we hypothesized that APOE4 genotype would beneficially influence the clinical course of CLL. Of the 193 CLL patients (50 women and 133 men) studied, 29% had an APOE4 genotype. In the entire group, survival of men and women was not statistically different. However, women (but not men) with an APOE4 genotype had markedly longer survival than non-APOE4 patients (median >25 yr vs. 14.0 yr; p = 0.02) (Figure). [Display omitted] Men and women had the same time-to-treatment (treatment-free survival) irrespective of APOE genotype. VLDL is metabolized to LDL by the actions of LPL. Patients had shorter survival and time-to-treatment if their CLL cell lipoprotein lipase (LPL) mRNA levels were high (p = 0.002). In analyzing APOE genotype and LPL levels in the same patients, we demonstrated that APOE4 was a more important determinant of survival than was the LPL level (p = 0.0007). The beneficial effect of APOE4 in CLL survival is likely mediated through allele-specific influences of APOE4 on serum lipoproteins increasing leukemia cell apoptosis. The frequency of the APOE alleles in the CLL patient population was not significantly different than that of a control population (16 and 13%, respectively). APOE genotype therefore does not appear to affect susceptibility to CLL, but influences the clinical course of disease, particularly after therapy is initiated. In contrast, APOE genotype does influence susceptibility to other diseases, most notably Alzheimer's disease in which APOE4 markedly increases risk. The beneficial impact of APOE4 in CLL and its deleterious impact on Alzheimer's disease expression may relate to a common mechanism of APOE4 in enhancing apoptotic cell death. APOE genotyping of patients with CLL may provide important clinical prognostic information, particularly in women. Most importantly, the allele-specific influence of APOE on disease progression may provide important new insights into the mechanisms of disease and response to therapy, and lead to new agents for treatment.

Improvement of hyperlipidemia by indomethacin in Min mice

Apc gene-deficient Min and Apc(1309) mice feature a hyperlipidemic state with a markedly low expression level of lipoprotein lipase (LPL) compared to their wild-type counterparts. We previously showed that induction of LPL mRNA by peroxisome proliferator-activated receptor (PPAR) alpha and gamma agonists or an LPL selective inducer suppresses both high serum lipid levels and intestinal polyp formation in these model animals. Since the general cyclooxygenase inhibitor, indomethacin, is known to suppress intestinal tumor development, but not to affect serum lipids, its influence in Min mice was here investigated. Treatment with 2.5, 5 and 10 ppm indomethacin in the diet for 14 weeks from 6 weeks of age caused significant dose-dependent reduction in serum triglycerides, along with a reduction in the numbers of intestinal polyps to 25% of the untreated control value. LPL mRNA levels in the liver were slightly increased by indomethacin treatment. We further performed oligonucleotide microarray analysis and quantitative PCR analysis and found 8 lipid metabolism-related genes, regulated by sterol regulatory element binding protein-1c, to be modulated by indomethacin-treatment in the Min mouse liver. Furthermore, TNFalpha was downregulated. These results indicate that indomethacin might suppress intestinal tumor formation together with a hyperlipidemic state by regulating LPL and other lipid metabolic factors.

EFFECTS OF ORAL CHONDROITIN SULFATE ON LIPID AND ANTIOXIDANT METABOLISMS IN RATS FED A HIGH-FAT DIET

This study aimed at determining the effects of purified chondroitin sulfate (ChS) from pig laryngeal cartilage on the lipid and antioxidant metabolisms of male Sprague-Dawley rats that are fed a high-fat diet. Thirty-two male rats were divided into four groups and fed for 5 weeks on a standard diet, a high-fat diet or a high-fat diet plus ChS. It was demonstrated that the high-fat diet provoked lipid peroxidation and induced a severe depletion of lipoprotein lipase, hepatic lipidase, glutathione, catalase and superoxide dismutase levels. ChS was effective in reducing triglycerides, total cholesterol, low-density-lipid cholesterol and malondialdehyde levels elevated by the high-fat diet. In addition, ChS might reduce the risk of atherosclerosis, as high-density-lipid cholesterol, lipoprotein lipase, hepatic lipidase and the ratio of high-density-lipoprotein cholesterol to total cholesterol were significantly higher than in the high-fat-diet rats. ChS restored the endogenous antioxidants glutathione, catalase and superoxide dismutase. These results showed that ChS was potent in lipid-lowering and altering the antioxidative enzyme; however, excess ChS would disturb lipid profiles that went beyond the normal limits.

Glycosylphosphatidylinositol-Anchored High-Density Lipoprotein-Binding Protein 1 Plays a Critical Role in the Lipolytic Processing of Chylomicrons

The triglycerides in chylomicrons are hydrolyzed by lipoprotein lipase (LpL) along the luminal surface of the capillaries. However, the endothelial cell molecule that facilitates chylomicron processing by LpL has not yet been defined. Here, we show that glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) plays a critical role in the lipolytic processing of chylomicrons. Gpihbp1-deficient mice exhibit a striking accumulation of chylomicrons in the plasma, even on a low-fat diet, resulting in milky plasma and plasma triglyceride levels as high as 5000 mg/dl. Normally, Gpihbp1 is expressed highly in heart and adipose tissue, the same tissues that express high levels of LpL. In these tissues, GPIHBP1 is located on the luminal face of the capillary endothelium. Expression of GPIHBP1 in cultured cells confers the ability to bind both LpL and chylomicrons. These studies strongly suggest that GPIHBP1 is an important platform for the LpL-mediated processing of chylomicrons in capillaries.

Comparison of Different Strategies of MSC Isolation Revels Advantage To Expand MSC Directly from Purified CD105+ and CD271+ Cells.

The potential for multilineage differentiation together with the ability to expand in cultures are the reasons why Mesenchymal Stem Cells (MSC) are considered to be the population of stem cells for potential treatment for variety of disorders (e. g. Osteogenesis Imperfecta, Myocardium Infarction, GvHD). MSC are isolated from the bone marrow mononuclear cells (MNC) based on their adhesive properties. There have been few attempts to isolate MSC directly based on the expression of selected surface antigens, but these isolation strategies were not compared with “the gold standard” procedure which is still selection by plastic adherence. Nevertheless, it is obvious that a presence of different populations of cells “contaminating” MSC in adherent cell cultures (e.g., endothelial cells, macrophages, dendritic cells) may affect expansion of MSC.In this study we proposed new isolation strategies of bone marrow MSC based on RosetteSep Isolation Kit (Stem Cells Technologies Inc., Vancouver, Canada) and immunomagnetic isolation of CD105+ or CD271+ cell populations (Miltenyi Biotec, Germany). Four fractions of bone marrow mononuclear cells i) non-purified MNC, ii) MNC enriched in MSC by RosetteSep Isolation Kit, iii) sorted CD105+ and iv) sorted CD271+ cells were cultured for three passages. Subsequently, we evaluated i) number of CFU-F colonies, ii) expression of selected surface antigens (CD105, CD166, CD44, CD73, CD45, CD34), iii) in vitro osteogenic differentiation of expanded cells and iv) changes in the expression of genes related to osteogenesis (RQ-PCR). We found that the mean number of CFU-F colonies counted on the 9th day of culture was 26 (range 14,5–41,4), 49 (range 21,2–97,1), 105 (range 36,5–221) and 148 (range 55,3–211) per 107 MNC for non-purified MNC, MNC enriched in MSC by RosetteSep Isolation Kit, purified CD105+cells and purified CD271+cells, respectively. After 3rd passage the phenotype of cells was similar as we observed a comparable percentage of cells positive (over 90%) for CD105, CD166, CD44, CD73 and negative (below 5%) for CD45, CD34 surface antigens in all fractions. The RQ - PCR analysis of mRNA level of osteogenic (osteocalcin, PTHR, α1collagen), adipogenic (lipoprotein lipase, leptin, PPARγ2) and chondrogenic (aggrecan1) genes in all four populations revealed that MSC isolated by means of expression of 105 and CD271 antigens had higher level of mRNA for all assessed genes except for lipoprotein lipase and α1collagen prior to differentiation. After 30 days of osteogenic differentiation RQ - PCR analysis was repeated and compared with that before differentiation. We noticed an increased level of mRNA for osteocalcin and PTHR (markers of osteogenic differentiation) in all four populations, with the highest expression in MSC derived from non-purified MNC. However, this fraction had also the highest mRNA level of PPARγ2, lipoprotein lipase, and aggrecan genes (adipogenic and chondrogenic lineage respectively).Since the highest number of CFU-F was derived from purified CD105+ and CD271+ cells as well as these two populations seem to be the most homogenous based on RQ-PCR data, these cell fractions should be employed to expand most efficiently MSC for potential therapeutic purposes. Our data suggest that, non-MSC cells present in MNC and RosetteSep cultures may negatively affect both the expansion efficiency and differentiation along desired MSC lineage.

Endothelial bound lipoprotein lipase (LpL) depletion in hypoalbuminemia results from decreased endothelial binding, not decreased secretion

Hypertriglyceridemia in nephrotic (NS) and Nagase analbuminemic rats (Analb) results from reduced triglyceride clearance. NS and Analb have reduced or absent albumin, reduced plasma oncotic pressure (pi), but Analb lack proteinuria. The heparin releasable lipoprotein lipase (LpL) pool in both models is greatly reduced, suggesting reduced LpL is related to low albumin or pi and not proteinuria. To determine the cause of endothelial LpL reduction, we studied effectors of endothelial LpL (eLpL) levels from gene expression, to delivery and endothelial binding. eLpL was measured as heparin releasable activity. eLpL and secretion rate was measured in isolated hearts perfused with heparin. mRNA levels were measured in rat hearts by kinetic RT-PCR. Finally, binding of (125)I-LpL by competition assays rat endothelial cells measured serum-induced changes in affinity. eLpL in vivo was reduced in nephrotic and Analb rats. While the eLpL pool was reduced in isolated perfused hearts, neither LpL secretion by isolated hearts nor myocardial mRNA was reduced in NS or Analb. Binding of LpL to RAEC preincubated with serum from either NS or Analb was reduced compared to control. LpL mRNA levels and release rate was not altered in hearts from NS rats, while eLpL is depleted, suggesting that reduced eLpL in NS is not the result of reduced delivery. The finding that NS serum alters LpL binding to RAEC suggests LpL depletion results from decreased binding rather than defective delivery. This in turn is a consequence of reduced serum albumin or pi but does not require proteinuria.