Ciprofibrate increases cholesteryl ester transfer protein gene expression and the indirect reverse cholesterol transport to the liver

Human cholesteryl ester transport protein transgene promotes macrophage reverse cholesterol transport in C57BL/6 mice and phospholipid transfer protein gene knockout mice

Cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) belong to the same gene family. Liver-specific expression of CETP improves reverse cholesterol transport (RCT) and PLTP knockout (KO) decreases RCT in mice. In this study, we investigate the effect of CETP transgene (CETP-tg) on RCT and whether CETP-tg can partially restore RCT efficiency in PLTP KO mice. Several rounds of crossing were carried out to produce colonies of wild type (WT), CETP-tg, PLTP KO, and CETP-tg × PLTP KO mice were obtained after several generations of reproduction. The efficiency of RCT was detected using [³H]-cholesterol-laden macrophages, and the underlying mechanisms were investigated by multiple techniques. Our data demonstrated that CETP-tg significantly increased the transport rate of [³H]-cholesterol from macrophages to plasma and liver, and finally the excretion through feces compared to the WT littermates. The RCT improving effect of CETP-tg was similar in PLTPKO mice. Furthermore, CETP-tg did not affect the expression of RCT-related proteins, such as low-density lipoprotein receptor. The mechanisms of improving RCT may be attributed to the low level of oxidized lipids in CETP-tg mouse and CETP-mediated lipid transport. Collectively, CETP-tg improves RCT in mice, and CETP can not compensate for PLTP deficiency.

Associations between repeated measure of plasma perfluoroalkyl substances and cardiometabolic risk factors

BACKGROUND

Perfluoroalkyl substances (PFAS) are persistent synthetic chemicals that may affect components of metabolic risk through the peroxisome proliferator-activated receptor but epidemiological data remain scarce and inconsistent.

OBJECTIVE

To estimate associations between repeated measurements of the main PFAS in plasma and total cholesterol, triglycerides and hypertension among the control subjects from a population-based nested case-control study on diabetes type 2 in middle-aged women and men.

METHODS

Participants (n = 187) were free of diabetes at both baseline and follow-up visits to the Västerbotten Intervention Programme, 10 years apart: during 1990 to 2003 (baseline) and 2001 to 2013 (follow-up). Participants left blood samples, completed questionnaires on diet and lifestyle factors, and underwent medical examinations, including measurement of blood pressure. PFAS and lipids were later determined in stored plasma samples. Associations for the repeated measurements were assessed using generalized estimating equations.

RESULTS

Six PFAS exceeded the limit of quantitation. Repeated measures of PFAS in plasma, cardiometabolic risk factors and confounders, showed an average decrease of triglycerides from -0.16 mmol/l (95% confidence interval [CI]: -0.33, 0.02 for PFOA) to -0.26 mmol/l (95% CI: -0.50, -0.08 for PFOS), when comparing the highest tertile of PFAS plasma levels with the lowest. Associations based on average PFAS measurements and follow-up triglycerides revealed similar inverse associations, although attenuated. The estimates for cholesterol and hypertension were inconsistent and with few exception non-significant.

CONCLUSIONS

This study found inverse associations between PFAS and triglycerides, but did not support any clear link with either cholesterol or hypertension.

Combined Effect of Diosgenin Along with Ezetimibe or Atorvastatin on the Fate of Labelled Bile Acid and Cholesterol in Hypercholesterolemic Rats

We analyzed the effect of diosgenin, administered with atorvastatin or ezetimibe, on the fate of ³H(G)-taurocholic acid or 26-¹⁴C-cholesterol in hypercholesterolemic rats. Male Wistar rats received a hypercholesterolemic diet (HD), HD + atorvastatin (HD+ATV), HD + ezetimibe (HD+EZT), HD + diosgenin (HD+DG), HD+ATV+EZT, or HD+ATV+DG for 40 days. We also included a control normal group (ND). The labelled compounds were administered on day 30. The animals were placed in metabolic cages for daily feces collection. At day 40 the rats were sacrificed. Lipid extracts from blood, liver, spinal cord, testicles, kidneys, epididymis, intestine, and feces were analyzed for radioactivity. Cholesterol activity was the highest in the liver in HD rats. DG diminished one half of this activity in HD+DG and HD+ATV+DG groups in comparison with the HD group. HD+ATV rats showed four to almost ten-fold cholesterol activity in the spinal cord compared with the ND or HD rats. Fecal elimination of neutral steroids was approximately two-fold higher in the HD+DG and HD+ATV+DG groups. Taurocholic acid activity was four to ten-fold higher in HD+DG intestine as compared to the other experimental groups. Taurocholic activity in the liver of HD and HD+DG groups was two and a half higher than in ND. Our results show that the combination of DG and ATV induced the highest cholesterol reduction in the liver and other tissues.

Hematological indicators in pygmy wood mouse Apodemus uralensis (Muridae, Rodentia) populations as markers of the environmental radiation exposure: East Urals radioactive trace (Russia)

The hematological effects of chronic radiation exposure in males of the pygmy wood mouse (Apodemus uralensis Pall., 1811) from the East Urals radioactive trace (EURT) area were assessed, taking into account population abundance and reproductive status (immature, ripening, and mature yearlings). For this purpose, we analyzed the morpho-functional characteristics of erythrocytes (red cell indices [MCV, MCH, MCHC], red cell count, activity of antioxidant enzymes [GSH-Px, CAT], lipid peroxidation, glycolysis, osmotic resistance, methaemoglobin content) and blood plasma components (free hemoglobin, total lipids, total cholesterol, and glucose) in the background territory and the EURT area; these areas have a density of soil contamination with ⁹⁰Sr of 12,851 and 198 kBq × m^-2, respectively (four and two order of magnitude higher than the background value). The data indicate the "hyperfunctional" state of the erythrocyte, aimed at activation of the gas transport function of blood in the radioactive environment. This, as a consequence, determines the insufficiency of energy supply of the cell defense system necessary to maintain the structural integrity of the membrane. Intensification of membrane lipid peroxidation, reduction of osmotic resistance and GSH-Px activity in red cells, an increase in the degree of intravascular hemolysis, and tendency towards erythropenia indicate the processes of accelerated aging of erythrocytes and their more pronounced destruction in the circulatory bed. The level of the hematological response increased with increasing radiation burden and was more pronounced with a large population size. The interaction effect of "overpopulation" and "radioactive pollution" was observed to a lesser degree for ripening males, and was very small for sexually mature animals. Immature males from the EURT head part with internal whole-body radiation doses of 0.0045-0.35 mGy/day can be considered as the most sensitive group to the factors synergy, including radiation damage and overabundance population.

Cholesteryl Ester Transfer Protein (CETP) expression does not affect glucose homeostasis and insulin secretion: studies in human CETP transgenic mice

Background

Cholesteryl ester transfer protein (CETP) is a plasma protein that mediates the exchange of triglycerides for esterified cholesterol between HDL and apoB-lipoproteins. Previous studies suggest that CETP may modify glucose metabolism in patients or cultured cells. In this study, we tested if stable CETP expression would impair glucose metabolism.

Methods

We used human CETP transgenic mice and non-transgenic littermate controls (NTg), fed with control or high fat diet, as well as in dyslipidemic background and aging conditions. Assays included glucose and insulin tolerance tests, isolated islets insulin secretion, tissue glucose uptake and adipose tissue GLUT mRNA expression.

Results

CETP expression did not modify glucose or insulin tolerance in all tested conditions such as chow and high fat diet, adult and aged mice, normo and dyslipidemic backgrounds. Fasting and fed state plasma levels of insulin were not differ in CETP and NTg mice. Direct measurements of isolated pancreatic islet insulin secretion rates induced by glucose (11, 16.7 or 22 mM), KCl (40 mM), and leucine (10 mM) were similar in NTg and CETP mice, indicating that CETP expression did not affect β-cell function in vivo and ex vivo. Glucose uptake by insulin target tissues, measured in vivo using ³H-2-deoxyglucose, showed that CETP expression had no effect on the glucose uptake in liver, muscle, perigonadal, perirenal, subcutaneous and brown adipose tissues. Accordingly, GLUT1 and GLUT4 mRNA in adipose tissue were not affected by CETP.

Conclusions

In summary, by comparing the in vivo all-or-nothing CETP expressing mouse models, we demonstrated that CETP per se has no impact on the glucose tolerance and tissue uptake, global insulin sensitivity and beta cell insulin secretion rates.

Apolipoprotein CIII overexpression exacerbates diet-induced obesity due to adipose tissue higher exogenous lipid uptake and retention and lower lipolysis rates

Background

Hypertriglyceridemia is a common type of dyslipidemia found in obesity. However, it is not established whether primary hyperlipidemia can predispose to obesity. Evidences have suggested that proteins primarily related to plasma lipoprotein transport, such as apolipoprotein (apo) CIII and E, may significantly affect the process of body fat accumulation. We have previously observed an increased adiposity in response to a high fat diet (HFD) in mice overexpressing apoCIII. Here, we examined the potential mechanisms involved in this exacerbated response of apoCIII mice to the HFD.

Methods

We measured body energy balance, tissue capacity to store exogenous lipids, lipogenesis and lipolysis rates in non-transgenic and apoCIII overexpressing mice fed a HFD during two months.

Results

Food intake, fat excretion and whole body CO₂ production were similar in both groups. However, the adipose tissue mass (45 %) and leptin plasma levels (2-fold) were significantly greater in apoCIII mice. Lipogenesis rates were similar, while exogenous lipid retention was increased in perigonadal (2-fold) and brown adipose tissues (40 %) of apoCIII mice. In addition, adipocyte basal lipolysis (55 %) and in vivo lipolysis index (30 %) were significantly decreased in apoCIII mice. A fat tolerance test evidenced delayed plasma triglyceride clearance and greater transient availability of non-esterified fatty acids (NEFA) during the post-prandial state in the apoCIII mice plasma. Thus, apoCIII overexpression resulted in increased NEFA availability to adipose uptake and decreased adipocyte lipolysis, favoring lipid enlargement of adipose depots.

Conclusion

We propose that plasma apoCIII levels represent a new risk factor for diet-induced obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-015-0058-6) contains supplementary material, which is available to authorized users.

The Ethanol Extract from Lonicera japonica Thunb. Regresses Nonalcoholic Steatohepatitis in a Methionine- and Choline-Deficient Diet-Fed Animal Model

Nonalcoholic steatohepatitis (NASH) is characterized as fat accumulation in the hepatic tissue associated with various degrees of inflammation and progressive fibrosis. The potent anti-inflammatory and ethnopharmacological properties of Lonicera japonica Thunb. (Caprifoliaceae) make it an excellent source of novel medicinal targets for the treatment of NASH. The aim of the study was to investigate the effects of L. japonica ethanol extract (LJEE) on NASH in mice. C57BL/6J mice were fed with methionine-choline-deficient diet (MCDD) for eight weeks to promote the development of NASH. After development of the model, the mice were administered LJEE once daily via oral gavage at doses of 100, 200, or 300 mg/kg for another four weeks. Simultaneous treatments with LJEE (300 mg/kg/day) resulted in pronounced improvements in liver steatosis, ballooning degeneration, and inflammation. LJEE prevented MCDD-induced plasma level increases in aspartate aminotransferase and alanine aminotransferase. LJEE significantly reduced hepatic malondialdehyde level and ameliorated hepatic inflammation and fibrosis in MCDD-fed mice, which were associated with down-regulation of cytochrome P450 2E1 suppression of multiple proinflammatory and profibrotic genes. LJEE can prevent hepatic steatosis by reducing hepatic peroxisome acyl-CoA:diacylglycerol acyltransferase 2 expression, as well as by inducing proliferator-activated receptor α expression. In addition, the LJEE treatments caused significant reduction in the phosphorylated form of Jun N-terminal kinase along with an increase in the phosphorylated level of extra cellular signal-regulated kinase 1/2. Our study demonstrated the protective role of LJEE in ameliorating nutritional steatohepatitis.

Stability-indicating liquid chromatographic and UV spectrophotometric methods for the quantification of ciprofibrate in capsules and tablets

This study describes the development and evaluation of stability-indicating liquid chromatographic (LC) and UV spectrophotometric methods for the quantification of ciprofibrate (CPF) in tablets and capsules. Isocratic LC separation was achieved on a RP18 column using a mobile phase of o-phosphoric acid (0.1% v/v), adjusted to pH 3.0 with triethylamine (10% v/v) and acetonitrile (35:65 v/v), with a flow rate of 1.0 mL min-1. Detection was achieved with a photodiode array detector at 233 nm. For the spectrophotometric analysis, ethanol and water were used as the solvent and a wavelength of 233 nm was selected for the detection. The methods were validated according to International Conference on Harmonization (ICH) guidelines for validating analytical procedures. Statistical analysis showed no significant difference between the results obtained by the two methods. The proposed methods were successfully applied to the CPF quality-control analysis of tablets and capsules.

6-gingerol protects against nutritional steatohepatitis by regulating key genes related to inflammation and lipid metabolism

Non-alcoholic fatty liver disease, including non-alcoholic steatohepatitis (NASH), appears to be increasingly common worldwide. The aim of the study was to investigate the effects of 6-gingerol ((S)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-3-decanone), a bioactive ingredient of plants belonging to the Zingiberaceae family, on experimental models of NASH. In HepG2 cells, 6-gingerol (100 μmol/L) treatment inhibited free fatty acids mixture (0.33 mmol/L palmitate and 0.66 mmol/L oleate)-induced triglyceride and inflammatory marker accumulations. Male C57BL/6 mice were fed with a methionine and choline-deficient (MCD) diet to induce steatohepatitis. After four weeks of MCD diet feeding, the mice were dosed orally with 6-gingerol (25, 50 or 100 mg/kg/day) once daily for another four weeks. 6-Gingerol (100 mg/kg/day) attenuated liver steatosis and necro-inflammation in MCD diet-fed mice. The expressions of inflammatory cytokine genes, including those for monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin-6, and nuclear transcription factor (NF-κB), which were increased in the livers of MCD diet-fed mice, were attenuated by 6-gingerol. 6-Gingerol possesses a repressive property on hepatic steatosis, which is associated with induction of peroxisome proliferator-activated receptor α. Our study demonstrated the protective role of 6-gingerol in ameliorating nutritional steatohepatitis. The effect was mediated through regulating key genes related to lipid metabolism and inflammation.

Fibrates and fish oil, but not corn oil, up-regulate the expression of the cholesteryl ester transfer protein (CETP) gene

Cholesteryl ester transfer protein (CETP) is a plasma protein that reduces high density lipoprotein (HDL)-cholesterol (chol) levels and may increase atherosclerosis risk. n-3 and n-6 polyunsaturated fatty acids (PUFAs) are natural ligands, and fibrates are synthetic ligands for peroxisome proliferator activated receptor-alpha (PPARα), a transcription factor that modulates lipid metabolism. In this study, we investigated the effects of PUFA oils and fibrates on CETP expression. Hypertriglyceridemic CETP transgenic mice were treated with gemfibrozil, fenofibrate, bezafibrate or vehicle (control), and normolipidemic CETP transgenic mice were treated with fenofibrate or with fish oil (FO; n-3 PUFA rich), corn oil (CO, n-6 PUFA rich) or saline. Compared with the control treatment, only fenofibrate significantly diminished triglyceridemia (50%), whereas all fibrates decreased the HDL-chol level. Elevation of the CETP liver mRNA levels and plasma activity was observed in the fenofibrate (53%) and gemfibrozil (75%) groups. Compared with saline, FO reduced the plasma levels of nonesterified fatty acid (26%), total chol (15%) and HDL-chol (20%). Neither of the oil treatments affected the plasma triglyceride levels. Compared with saline, FO increased the plasma adiponectin level and reduced plasma leptin levels, whereas CO increased the leptin levels. FO, but not CO, significantly increased the plasma CETP mass (90%) and activity (23%) as well as increased the liver level of CETP mRNA (28%). In conclusion, fibrates and FO, but not CO, up-regulated CETP expression at both the mRNA and protein levels. We propose that these effects are mediated by the activation of PPARα, which acts on a putative PPAR response element in the CETP gene.

Multiple sclerosis is not a disease of the immune system

Multiple sclerosis is a complex neurodegenerative disease, thought to arise through autoimmunity against antigens of the central nervous system. The autoimmunity hypothesis fails to explain why genetic and environmental risk factors linked to the disease in one population tend to be unimportant in other populations. Despite great advances in documenting the cell and molecular mechanisms underlying MS pathophysiology, the autoimmunity framework has also been unable to develop a comprehensive explanation of the etiology of the disease. I propose a new framework for understanding MS as a dysfunction of the metabolism of lipids. Specifically, the homeostasis of lipid metabolism collapses during acute-phase inflammatory response triggered by a pathogen, trauma, or stress, starting a feedback loop of increased oxidative stress, inflammatory response, and proliferation of cytoxic foam cells that cross the blood brain barrier and both catabolize myelin and prevent remyelination. Understanding MS as a chronic metabolic disorder illuminates four aspects of disease onset and progression: 1) its pathophysiology; 2) genetic susceptibility; 3) environmental and pathogen triggers; and 4) the skewed sex ratio of patients. It also suggests new avenues for treatment.