Low high-density lipoprotein cholesterol disorders and cardiovascular risk: contribution of associated low-density lipoprotein subclass abnormalities

Leptin decreases the expression of low-density lipoprotein receptor via PCSK9 pathway: linking dyslipidemia with obesity

Background

Previous studies have suggested that people with obesity showed elevated serum levels of leptin as well as lipid dysfunction and proprotein convertase subtilisin/kexin type 9 (PCSK9) played an important role in the regulation of lipid metabolism recently. The aim of this study was to determine if leptin participated in regulating the uptake of low-density lipoproteins (LDL) in hepatocytes via PCSK9.

Methods

HepG2 cells were treated with human recombinant leptin. The impact of leptin on cellular low density lipoprotein receptor (LDLR) and PCSK9 protein levels was determined by Western blot. Dil-LDL uptake assay was performed to examine the LDLR function. Specific small interfering RNAs (siRNAs) were used to interfere the expressions of target proteins.

Results

The expression of LDLR and LDL uptake could be significantly down-regulated by leptin treatment while the expressions of PCSK9 and hepatocyte nuclear factor 1α (HNF1α) were enhanced in HepG2 cells. Furthermore, inhibition of PCSK9 or HNF1α expression by siRNAs rescued the reduction of LDLR expression and LDL uptake by leptin. We found that leptin activated the p38 mitogen-activated protein kinase (p38MAPK) signaling pathway. Moreover, the changes of the expressions of HNF1α, PCSK9, LDLR, and LDL uptake induced by leptin could be blocked by p38MAPK inhibitor (SB203580). Additionally, leptin attenuated the up-regulation of LDLR caused by atorvastatin in HepG2 cells.

Conclusions

These findings indicated firstly that leptin reduced LDLR levels in hepatocyte via PCSK9 pathway, suggesting that PCSK9 might be a alternative target for dyslipidemia in the obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1032-4) contains supplementary material, which is available to authorized users.

Simultaneous analysis of gemfibrozil, morphine, and its two active metabolites in different mouse brain structures using solid-phase extraction with ultra-high performance liquid chromatography and tandem mass spectrometry with a deuterated internal standard

A rapid and sensitive bioassay was established and validated to simultaneously determine gemfibrozil, morphine, morphine-3β-glucuronide, and morphine-6β-glucuronide in mouse cerebrum, epencephalon, and hippocampus based on ultra-high performance liquid chromatography and tandem mass spectrometry. The deuterated internal standard, M6G-d3, was mixed with the prepared samples at 10 ng/mL as the final concentration. The samples were transferred into the C18 solid-phase extraction columns with gradient elution for solid-phase extraction. The mobile phase consisted of methanol and 0.05% formic acid (pH 3.2). Multiple reaction monitoring has been applied to analyze gemfibrozil (m/z 249.0 → 121.0) in anion mode, and M6G-d3 (m/z 465.1 → 289.1), morphine (m/z 286.0 → 200.9), and M3G and M6G (m/z 462.1 → 286.1) in the positive ion mode. The method has a linear calibration range from 0.05 to 10 ng for gemfibrozil, morphine, and M3G and M6G with correlation coefficients >0.993. The lower limit of quantitation for all four analytes was 0.05 ng/mL, relative standard deviation of intra- and interday precision was less than 10.5%, and the relative error of accuracy was from -8.2 to 8.3% at low, medium, and high concentrations for all the analytes. In conclusion, gemfibrozil can influence the morphine antinociception after coronary heart disease induced chronic angina by the change in one of morphine metabolites', M3G, distribution in mouse brain.

The association between metabolic syndrome and pressure ulcers among individuals living with spinal cord injury

OBJECTIVE

The objective of this study was to identify the relationship between metabolic syndrome (MetS) and pressure ulcers (PrU), after controlling for demographic and injury characteristics, socioeconomic factors, health behaviors and fatigue among participants with spinal cord injury (SCI).

METHODS

This cross-sectional study recruited 350 participants with SCI from a hospital in the western region of the USA. Blood tests and physical examination were performed. Waist circumference, high-density cholesterol, triglycerides, blood pressure and fasting glucose were used to diagnose MetS according to Criteria for Clinical Diagnosis of Metabolic Syndrome defined by the American Heart Association. All other variables were self-reported. Three-stage multivariate logistic regression models were conducted to evaluate the effects of three sequential sets of predictors, including demographic/injury, socio-environmental/behavioral and health factors, basing the order of analysis on the Theoretical Risk and Prevention Model.

RESULTS

The prevalence of PrU and MetS was 11.0% (n=36) and 35.3% (n=115), respectively. Ethnicity, smoking, alcohol consumption and MetS were statistically associated with PrU in the full model. Participants who were non-Hispanic (odds ratio (OR)=10.30, 95% confidence interval (CI): 3.46-30.65), smokers (OR=2.69, 95% CI: 1.00-7.27) and drank over 30 drinks per month (OR=5.26, 95% CI: 1.24-22.26) had greater odds of having a PrU compared with those who were Hispanic, non-smokers and non-drinkers, respectively. We also observed a positive association between MetS and PrU (OR_MetS=3.71, 95% CI: 1.45-9.52), even after controlling for all other factors.

CONCLUSION

Participants who had MetS had higher odds of PrU than those without MetS after adjusting for multiple covariates. Unhealthy behaviors such as smoking and excess drinking were positively associated with PrU.

Modulation of fatty acid transport and metabolism by maternal obesity in the human full-term placenta

Knowledge of the consequences of maternal obesity in human placental fatty acids (FA) transport and metabolism is limited. Animal studies suggest that placental uptake of maternal FA is altered by maternal overnutrition. We hypothesized that high maternal body mass index (BMI) affects human placental FA transport by modifying expression of key transporters. Full-term placentas were obtained by vaginal delivery from normal weight (BMI, 18.5-24.9 kg/m(2)) and obese (BMI > 30 kg/m(2)) women. Blood samples were collected from the mother at each trimester and from cord blood at delivery. mRNA and protein expression levels were evaluated with real-time RT-PCR and Western blotting. Lipoprotein lipase (LPL) activity was evaluated using enzyme fluorescence. In vitro linoleic acid transport was studied with isolated trophoblasts. Our results demonstrated that maternal obesity is associated with increased placental weight, decreased gestational age, decreased maternal high-density lipoprotein (HDL) levels during the first and third trimesters, increased maternal triglyceride levels during the second and third trimesters, and increased maternal T3 levels during all trimesters, and decreased maternal cholesterol (CHOL) and low-density lipoprotein (LDL) levels during the third trimester; and increased newborn CHOL, LDL, apolipoprotein B100, and T3 levels. Increases in placental CD36 mRNA and protein expression levels, decreased SLC27A4 and FABP1 mRNA and protein and FABP3 protein expression, and increased LPL activity and decreased villus cytotrophoblast linoleic acid transport were also observed. No changes were seen in expression of PPARA, PPARD, or PPARG mRNA and protein. Overall this study demonstrated that maternal obesity impacts placental FA uptake without affecting fetal growth. These changes, however, could modify the fetus metabolism and its predisposition to develop diseases later in life.

Systematic review, meta-analysis and regression of randomised controlled trials reporting an association between an intake of circa 25 g soya protein per day and blood cholesterol

AIMS

To determine the effect of a daily intake of circa 25 g soya protein on blood lipids in adults with normal or mildly elevated cholesterolaemia.

METHODS

Medline and other scientific databases were searched to identify randomised controlled trials (RCTs); these were systematically reviewed against pre-determined criteria. Eligible RCTs evaluated the effect of 25 g (range 15-40 g) soya protein on measures of blood lipids. Results from RCTs were pooled using standard meta-analysis methods.

RESULTS

Thirty studies containing 42 treatment arms (n=2913), with an average soya protein intake of 26.9 g met the inclusion criteria. Soya protein inclusion led to reductions in standard difference in mean low density lipoprotein (LDL), total cholesterol and blood triglycerides of 0.23 mmol/L (95% confidence interval (CI) -0.160 to -0.306, p<0.0001), 0.22 mmol/L (95% CI -0.142 to -0.291, p<0.0001) and 0.08 mmol/L (95% CI -0.004 to -0.158, p=0.04), respectively. There was no effect on mean difference in apolipoprotein A (ApoA), but ApoB was reduced by 0.021 g/L (p=0.01) in the soya group. Meta-regression analysis indicated no dose response relationship between soya protein intake in the range of 15-40 g and standard difference in LDL or HDL. All data were tested for heterogeneity and none identified.

CONCLUSIONS

The inclusion of modest amounts soya protein (ca. 25 g) into the diet of adults with normal or mild hypercholesterolaemia resulted in small, highly significant reductions in total and LDL cholesterol, equivalent to ca. 6% LDL reduction. This practically achievable intake, particularly when combined with other dietary measures, can make a useful contribution to blood cholesterol management.

Cardiovascular risks in spondyloarthritides

PURPOSE OF REVIEW

Spondyloarthritides are associated with increased cardiovascular risks, which can only partly be explained by traditional risk factors. It is likely that the chronic inflammatory state is involved. In this review, novel findings regarding cardiac and vascular pathologies and potential overlapping mechanisms will be discussed.

RECENT FINDINGS

Cardiac pathologies in spondyloarthritides are conduction disturbances and valvular heart diseases. Recent studies have also focused on vascular pathologies and showed impaired endothelial function, suggesting that atherosclerotic alterations could also be involved in increased cardiovascular mortality. Novel findings suggest that chronic systemic inflammation is involved in these cardiac and vascular pathologies. Thus, spondyloarthritides and ankylosing spondylitis are associated with increased levels of circulating inflammatory mediators such as C-reactive protein. Interestingly, ankylosing spondylitis patients may also have an atherogenic lipid profile and disturbances in their T-helper lymphocyte subsets, which may be involved in cardiovascular disease development. The beneficial effects of statin treatment on circulating inflammatory mediators and atherogenic lipid profiles may reveal new therapeutic options for patients with spondyloarthritides.

SUMMARY

Recent studies have highlighted that the chronic, systemic inflammatory condition of patients with spondyloarthritides may be involved in the development of cardiac and vascular pathologies.

Assessing risk across the spectrum of patients with the metabolic syndrome

The metabolic syndrome represents a constellation of interrelated risk factors that identify individuals at increased risk for the development of type 2 diabetes mellitus and cardiovascular events. Currently, the major cardiovascular risk factors and validated risk-assessment tools do not adequately account for the increased cardiovascular risk that accompanies the metabolic syndrome. In prospective population studies, cardiovascular risk assessment in individuals with the metabolic syndrome is improved by measures of low-density lipoprotein (LDL) particle number, C-reactive protein, and plasminogen activator inhibitor-1 levels. Although adiponectin and soluble tumor necrosis factor receptor-2 may be more integrally involved in insulin resistance, the studies with these biomarkers are less extensive. Risk assessment models for patients with the metabolic syndrome should consider inclusion of LDL particle number, inflammatory markers, and levels of plasminogen activator inhibitor-1.