Regulation of lipid metabolism-related gene expression in whole blood cells of normo- and dyslipidemic men after fish oil supplementation

A Systematic Review and Meta-Analysis of Lipid Signatures in Post-traumatic Stress Disorder

BACKGROUND

Research assessing lipid levels in individuals diagnosed with post-traumatic stress disorder (PTSD) has yielded mixed results. This study aimed to employ meta-analytic techniques to characterize the relationship between the levels of lipid profiles and PTSD.

METHODS

We performed meta-analyses of studies comparing profiles and levels of lipids between PTSD patients and healthy individuals by searching Embase, Ovid Medline, Scopus, PsycINFO, and Cochrane databases for the studies until March 2021. Meta-analyses were performed using random-effects models with the restricted maximum-likelihood estimator to synthesize the effect size assessed by standardized mean difference (SMD) across studies.

FINDINGS

A total of 8,657 abstracts were identified, and 17 studies were included. Levels of total cholesterol (TC) (SMD = 0.57 95% CI, 0.27-0.87, p = 0.003), low-density lipoprotein (LDL) (SMD = 0.48, 95% CI, 0.19-0.76, p = 0.004), and triglyceride (TG) (SMD = 0.46, 95% CI, 0.22-0.70, p = 0.001) were found to be higher, while levels of high-density lipoprotein (HDL) (SMD = -0.47, -0.88 to -0.07, p = 0.026) were found to be lower in PTSD patients compared to healthy controls. Subgroup analysis showed that TG levels were higher in PTSD patients who were on or off of psychotropic medications, both < 40 and ≥ 40 years of age, and having body mass index of < 30 and ≥ 30 compared to healthy controls.

INTERPRETATION

This work suggested dysregulation of lipids in PTSD that may serve as biomarker to predict the risk. The study will be useful for physicians considering lipid profiles in PTSD patients to reduce cardiovascular morbidity and mortality.

A systematic review and meta-analysis of lipid metabolomic signatures of Major Depressive Disorder

The aim of this meta-analysis was to provide a comprehensive synthesis of the evidence examining biomarker signatures in MDD patients including lipids, lipid regulatory proteins (LRP), and polyunsaturated fatty acid (PUFA) as compared to healthy individuals. We performed meta-analyses and meta-regression of the studies comparing lipid, LRP, and PUFA levels between MDD patients and healthy individuals by searching Embase, Ovid Medline, Scopus, PsycINFO, PubMed, and Cochrane databases. Search was performed in these databases up to September 2019 and 29 studies were included. Levels of lipid parameter triglyceride (TG) (SMD 0.55, 95% CI 0.30-0.80, p < 0.0001) were higher while total cholesterol (TC) (SMD = -0.46, 95%CI -0.93 to -0.001, p = 0.04) and very low-density lipoprotein (VLDL) (SMD = -0.46, 95%CI -0.71 to -0.20, p = 0.02) were lower in MDD patients than controls. Subgroup analysis for age showed that the levels of high-density lipoprotein (HDL) were lower in ≥40-year age group (SMD = -0.38, 95%CI -0.70 to -0.06, p = 0.01) and levels of TC was lower in MDD patients in studies from Asian countries (SMD = -0.74, 95%CI -1.37 to -0.10, p = 0.02). TG levels were found to be high all subgroups in MDD patients than controls. A negative association between TC levels and use of lipid lowering medications and a positive association between smoking and LDL levels was found using meta-regression analysis. This study will be useful for physicians when considering the assessment of lipidand LRP profiles in MDD patients to reduce the cardiovascular morbidity and mortality.

Increases in erythrocyte DHA are not associated with increases in LDL-cholesterol: Cooper center longitudinal study

BACKGROUND

The effects of fish oil products containing docosahexaenoic acid (DHA) on LDL-C levels are controversial.

OBJECTIVE

To determine if changes in erythrocyte DHA are associated with changes in LDL-C levels.

METHODS

In this prospective observational study, erythrocyte DHA levels and LDL-C levels were measured in 9253 individuals who presented for at least two examinations at a medical clinic. Changes in DHA levels and the reported use of omega-3 dietary supplements were correlated with changes in LDL-C in multi-variable adjusted models including the use of LDL-C-lowering drugs.

RESULTS

Mean (standard deviation) age at baseline was 52.6 (10.6) years, and the time between exams averaged 1.9 (1.4) years. As a group, erythrocyte DHA increased from 5.0% (1.3) to 5.3% (1.3) (p < 0.001), and LDL-C was not significantly changed (109 (33) to 108 (33) mg/dL, p = 0.875). However, in multivariable-adjusted models of within-participant changes, a 1% increase in erythrocyte DHA was associated with a 1.9 mg/dL reduction in LDL-C (95% confidence interval (1.6, 2.2), p < 0.001). Similar relationships were seen with changes in erythrocyte EPA and EPA + DHA. In adjusted analyses, an increased use of omega-3 supplements was associated with a significant increase in erythrocyte DHA and a decrease in LDL-C in both users and non-users of lipid-lowering drugs.

CONCLUSIONS

In a predominantly male, normolipidemic, middle-aged cohort, increases in erythrocyte DHA were associated with decreases in LDL-C, and initiating fish oil supplement use did not increase LDL-C. These findings may serve to reassure individuals who, in adopting a more heart-healthy lifestyle, want to increase their omega-3 fatty acid intake.

Distinguish fatty acids impact survival, differentiation and cellular function of periodontal ligament fibroblasts

Alveolar bone (AB) remodeling is necessary for the adaption to mechanical stimuli occurring during mastication and orthodontic tooth movement (OTM). Thereby, bone degradation and assembly are strongly regulated processes that can be altered in obese patients. Further, increased fatty acids (FA) serum levels affect bone remodeling cells and we, therefore, investigated whether they also influence the function of periodontal ligament fibroblast (PdLF). PdLF are a major cell type regulating the differentiation and function of osteoblasts and osteoclasts localized in the AB. We stimulated human PdLF (HPdLF) in vitro with palmitic (PA) or oleic acid (OA) and analyzed their metabolic activity, growth, survival and expression of osteogenic markers and calcium deposits. Our results emphasize that PA increased cell death of HPdLF, whereas OA induced their osteoblastic differentiation. Moreover, quantitative expression analysis of OPG and RANKL revealed altered levels in mechanically stimulated PA-treated HPdLF. Furthermore, osteoclasts stimulated with culture medium of mechanical stressed FA-treated HPdLF revealed significant changes in cell differentiation upon FA-treatment. For the first time, our results highlight a potential role of specific FA in the function of HPdLF-modulated AB remodeling and help to elucidate the complex interplay of bone metabolism, mechanical stimulation and obesity-induced alterations.

Early pregnancy dyslipidemia is associated with placental DNA methylation at loci relevant for cardiometabolic diseases

Aim: To identify placental DNA methylation changes that are associated with early pregnancy maternal dyslipidemia. Materials & methods: We analyzed placental genome-wide DNA methylation (n = 262). Genes annotating differentially methylated CpGs were evaluated for gene expression in placenta (n = 64). Results: We found 11 novel significant differentially methylated CpGs associated with high total cholesterol, low-density lipoprotein cholesterol and triglycerides, and low high-density lipoprotein cholesterol. High triglycerides were associated with decreased methylation of cg02785814 (ALX4) and decreased expression of ALX4 in placenta. Genes annotating the differentially methylated CpGs play key roles in lipid metabolism and were enriched in dyslipidemia pathways. Functional annotation found cis-methylation quantitative trait loci for genetic loci in ALX4 and EXT2. Conclusion: Our findings lend novel insights into potential placental epigenetic mechanisms linked with maternal dyslipidemia. Trial Registration: ClinicalTrials.gov, NCT00912132.

Intermittent Fasting in Cardiovascular Disorders-An Overview

Intermittent fasting is a form of time restricted eating (typically 16 h fasting and 8 h eating), which has gained popularity in recent years and shows promise as a possible new paradigm in the approach to weight loss and the reduction of inflammation, and has many potential long term health benefits. In this review, the authors will incorporate many aspects of fasting, mainly focusing on its effects on the cardiovascular system, involving atherosclerosis progression, benefits for diabetes mellitus type 2, lowering of blood pressure, and exploring other cardiovascular risk factors (such as lipid profile and inflammation).

An Improvement of Cardiovascular Risk Factors by Omega-3 Polyunsaturated Fatty Acids

An epidemiological survey in the Northwest Greenland reported that the Greenlanders have a lower frequency of acute myocardial infarction and diabetes mellitus. The very low incidence of ischemic heart disease in the Greenlanders was explained by consumption of a diet rich in omega-3 polyunsaturated fatty acids (PUFAs). Possible anti-atherothrombotic effects of omega-3 PUFA include an improvement of lipid metabolism such as a reduction of triglyceride and an increase of high-density lipoprotein-cholesterol (HDL-C), and glucose metabolism, anti-platelet activity, anti-inflammatory effects, an improvement of endothelial function and stabilization of atherosclerotic plaque. The present study reviews an improvement of cardiovascular risk factors such as dyslipidemia and diabetes due to consumption of omega-3 PUFA. A sufficient number of studies suggest that omega-3 PUFA supplementation reduces serum triglyceride and increases HDL-cholesterol. The mechanisms for omega-3 PUFA-mediated improvements of lipid metabolism have been partially elucidated. The studies using experimental animals, part of trials in humans, have shown the beneficial effects of omega-3 PUFA on glucose metabolism and insulin sensitivity. The meta-analysis showed that omega-3 PUFA might prevent development of diabetes in part of population. Further studies should be performed to elucidate the association of omega-3 PUFA supplementation with diabetes, in the future.

Omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid and their mechanisms of action on apolipoprotein B-containing lipoproteins in humans: a review

Background

Epidemiological and genetic studies suggest that elevated triglyceride (TG)-rich lipoprotein levels in the circulation increase the risk of cardiovascular disease. Prescription formulations of omega-3 fatty acids (OM3FAs), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), reduce plasma TG levels and are approved for the treatment of patients with severe hypertriglyceridemia. Many preclinical studies have investigated the TG-lowering mechanisms of action of OM3FAs, but less is known from clinical studies.

Methods

We conducted a review, using systematic methodology, of studies in humans assessing the mechanisms of action of EPA and DHA on apolipoprotein B-containing lipoproteins, including TG-rich lipoproteins and low-density lipoproteins (LDLs). A systematic search of PubMed retrieved 55 articles, of which 30 were used in the review; 35 additional arrticles were also included.

Results

In humans, dietary DHA is retroconverted to EPA, while production of DHA from EPA is not observed. Dietary DHA is preferentially esterified into TGs, while EPA is more evenly esterified into TGs, cholesterol esters and phospholipids. The preferential esterification of DHA into TGs likely explains the higher turnover of DHA than EPA in plasma. The main effects of both EPA and DHA are decreased fasting and postprandial serum TG levels, through reduction of hepatic very-low-density lipoprotein (VLDL)-TG production. The exact mechanism for reduced VLDL production is not clear but does not include retention of lipids in the liver; rather, increased hepatic fatty acid oxidation is likely. The postprandial reduction in TG levels is caused by increased lipoprotein lipase activity and reduced serum VLDL-TG concentrations, resulting in enhanced chylomicron clearance. Overall, no clear differences between the effects of EPA and DHA on TG levels, or on turnover of TG-rich lipoproteins, have been observed. Effects on LDL are complex and may be influenced by genetics, such as APOE genotype.

Conclusions

EPA and DHA diminish fasting circulating TG levels via reduced production of VLDL. The mechanism of reduced VLDL production does not involve hepatic retention of lipids. Lowered postprandial TG levels are also explained by increased chylomicron clearance. Little is known about the specific cellular and biochemical mechanisms underlying the TG-lowering effects of EPA and DHA in humans.

Effect of DHA-rich fish oil on PPARγ target genes related to lipid metabolism in type 2 diabetes: A randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

The beneficial effects of omega-3 polyunsaturated fatty acids on lipid levels are well documented. However, the related molecular mechanisms are widely unknown. Omega-3 polyunsaturated fatty acids are natural ligand for peroxisome proliferator-activated receptor γ (PPARγ).

OBJECTIVE

The aim of this study was to evaluate the effect of docosahexaenoic acid (DHA)-rich fish oil supplementation on modulation of some PPARγ-responsive genes related to lipid metabolism.

METHODS

Patients with type 2 diabetes were randomly assigned to consume either DHA-rich fish oil (containing 2400 mg/d fish oil; DHA: 1450 mg and eicosapentaenoic acid: 400 mg) or placebo for 8 weeks. Lipid profile and glycemic control parameters as well as the gene expression of PPARγ, liver x receptor-a, ATP-binding cassette A1, and CD36 in peripheral blood mononuclear cells were measured at baseline and after 8 weeks.

RESULTS

DHA-rich fish oil supplementation resulted in decreased triglycerides (TG) level compared with placebo group, independently of the baseline value of TG (all patients (P = .003), hypertriglyceridemic subjects (P = .01), and normotriglyceridemic subjects (P = .02)). Moreover, a higher reduction in TG level was observed in hypertriglyceridemic subjects, comparing to normotriglyceridemic subjects with DHA-rich fish oil supplementation (P = .01). Other lipid parameters as well as the expression of PPARγ, liver x receptor-a, ATP-binding cassette A1, and CD36 were not affected by DHA-rich fish oil supplementation. Only in hypertriglyceridemic subjects, DHA-rich fish oil supplementation upregulated CD36 expression, compared with the placebo group (P = .01).

CONCLUSIONS

DHA-rich fish oil supplementation for 8 weeks increased CD36 expression in hypertriglyceridemic subjects, which might result to higher reduction in TG level, comparing with normotriglyceridemic subjects. However, this finding should be investigated in further studies.

Transcriptome-based identification of new anti-inflammatory and vasodilating properties of the n-3 fatty acid docosahexaenoic acid in vascular endothelial cell under proinflammatory conditions [corrected]

Scope

High intakes of n-3 fatty acids exert anti-inflammatory effects and cardiovascular protection, but the underlying molecular basis is incompletely defined. By genome-wide analysis we searched for novel effects of docosahexaenoic acid (DHA) on gene expression and pathways in human vascular endothelium under pro-inflammatory conditions.

Methods and Results

Human umbilical vein endothelial cells were treated with DHA and then stimulated with interleukin(IL)-1β. Total RNA was extracted, and gene expression examined by DNA microarray. DHA alone altered the expression of 188 genes, decreasing 92 and increasing 96. IL-1β changed the expression of 2031 genes, decreasing 997 and increasing 1034. Treatment with DHA before stimulation significantly affected the expression of 116 IL-1β-deregulated genes, counter-regulating the expression of 55 genes among those decreased and of 61 among those increased. Functional and network analyses identified immunological, inflammatory and metabolic pathways as the most affected. Newly identified DHA-regulated genes are involved in stemness, cellular growth, cardiovascular system function and cancer, and included cytochrome p450 4F2(CYP4F2), transforming growth factor(TGF)-β2, Cluster of Differentiation (CD)47, caspase recruitment domain(CARD)11 and phosphodiesterase(PDE)5α.

Conclusions

Endothelial exposure to DHA regulates novel genes and related pathways. Such unbiased identification should increase our understanding of mechanisms by which n-3 fatty acids affect human diseases.

Effect of omega-3 polyunsaturated fatty acids on the cytoskeleton: an open-label intervention study

Background

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) show beneficial effects on cardiovascular health and cognitive functions, but the underlying molecular mechanisms are not completely understood. Because of the fact that cytoskeleton dynamics affect almost every cellular process, the regulation of cytoskeletal dynamics could be a new pathway by which n-3 PUFAs exert their effects on cellular level.

Methods

A 12-week open-label intervention study with 12 healthy men was conducted to determine the effects of 2.7 g/d n-3 PUFA on changes in mRNA expression of cytoskeleton-associated genes by quantitative real-time PCR in whole blood. Furthermore, the actin content in red blood cells was analyzed by immunofluorescence imaging.

Results

N-3 PUFA supplementation resulted in a significant down-regulation of cytoskeleton-associated genes, in particular three GTPases (RAC1, RHOA, CDC42), three kinases (ROCK1, PAK2, LIMK), two Wiskott-Aldrich syndrome proteins (WASL, WASF2) as well as actin related protein 2/3 complex (ARPC2, ARPC3) and cofilin (CFL1). Variability in F-actin content between subjects was high; reduced actin content was only reduced within group evaluation.

Conclusions

Reduced cytoskeleton-associated gene expression after n-3 PUFA supplementation suggests that regulation of cytoskeleton dynamics might be an additional way by which n-3 PUFAs exert their cellular effects. Concerning F-actin, this analysis did not reveal unmistakable results impeding a generalized conclusion.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-511X-14-4) contains supplementary material, which is available to authorized users.

Fish oil supplementation induces expression of genes related to cell cycle, endoplasmic reticulum stress and apoptosis in peripheral blood mononuclear cells: a transcriptomic approach

BACKGROUND

Fish oil supplementation has been shown to alter gene expression of mononuclear cells both in vitro and in vivo. However, little is known about the total transcriptome profile in healthy subjects after intake of fish oil. We therefore investigated the gene expression profile in peripheral blood mononuclear cells (PBMCs) after intake of fish oil for 7 weeks using transcriptome analyses.

DESIGN

In a 7-week, double-blinded, randomized, controlled, parallel-group study, healthy subjects received 8 g day(-1) fish oil (1.6 g day(-1) eicosapentaenoic acid + docosahexaenoic acid) (n = 17) or 8 g day(-1) high oleic sunflower oil (n = 19). Microarray analyses of RNA isolated from PBMCs were performed at baseline and after 7 weeks of intervention.

RESULTS

Cell cycle, DNA packaging and chromosome organization are biological processes found to be upregulated after intake of fish oil compared to high oleic sunflower oil using a moderated t-test. In addition, gene set enrichment analysis identified several enriched gene sets after intake of fish oil. The genes contributing to the significantly different gene sets in the subjects given fish oil compared with the control group are involved in cell cycle, endoplasmic reticulum (ER) stress and apoptosis. Gene transcripts with common motifs for 35 known transcription factors including E2F, TP53 and ATF4 were upregulated after intake of fish oil.

CONCLUSION

We have shown that intake of fish oil for 7 weeks modulates gene expression in PBMCs of healthy subjects. The increased expression of genes related to cell cycle, ER stress and apoptosis suggests that intake of fish oil may modulate basic cellular processes involved in normal cellular function.

Cloning and characterization of SREBP-1 and PPAR-α in Japanese seabass Lateolabrax japonicus, and their gene expressions in response to different dietary fatty acid profiles

In the present study, putative cDNA of sterol regulatory element-binding protein 1 (SREBP-1) and peroxisome proliferator-activated receptor α (PPAR-α), key regulators of lipid homoeostasis, were cloned and characterized from liver of Japanese seabass (Lateolabrax japonicus), and their expression in response to diets enriched with fish oil (FO) or fatty acids such as palmitic acid (PA), stearic acid (SA), oleic acid (OA), α-linolenic acid (ALA), and n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA), was investigated following feeding. The SREBP-1 of Japanese seabass appeared to be equivalent to SREBP-1a of mammals in terms of sequence feature and tissue expression pattern. The stimulation of the mRNA expression level of SREBP-1 in liver of Japanese seabass by dietary fatty acids significantly ranked as follows: PA, OA>SA, ALA, and n-3 LC-PUFA>FO. A new PPAR-α subtype in Japanese seabass, PPAR-α2, was cloned in this study, which is not on the same branch with Japanese seabass PPAR-α1 and mammalian PPAR-α in the phylogenetic tree. Liver gene expression of PPAR-α1 of Japanese seabass was inhibited by diets enriched with ALA or FO compared to diets enriched with PA or OA, while the gene expression of PPAR-α2 of Japanese seabass was up-regulated by diets enriched with ALA or n-3 LC-PUFA compared to diets enriched with OA or FO. This was the first evidence for the great divergence in response to dietary fatty acids between PPAR-α1 and PPAR-α2 of fish, which indicated probable functional distribution between PPAR-α isotypes of fish.

Vascular effects of the Mediterranean diet-part II: role of omega-3 fatty acids and olive oil polyphenols

The lower occurrence of cardiovascular disease and cancer in populations around the Mediterranean basin as detected in the 1950s was correctly attributed to the peculiar dietary habits of those populations. Essentially, until the mid-20th century, typical Mediterranean diets were rich in fruits, vegetables, legumes, whole-wheat bread, nuts, fish, and, as a common culinary trait, the routine use of extra-virgin olive oil. Nowadays, the regular adoption of such dietary patterns is still thought to result in healthful benefits. Such patterns ensure the assumption of molecules with antioxidant and anti-inflammatory actions, among which ω-3 polyunsaturated fatty acids (PUFAs), ω-9 monounsaturated fatty acids (oleic acid), and phenolic compounds. The aim of this review is to provide an update of the vasculo-protective pathways mediated by ω-3 PUFAs and polyphenols in the context of the modern Mediterranean dietary habits, including the possible cross-talk and synergy between these typical components. This review complements a parallel one focusing on the role of dietary nitrates and alimentary fats.

Dietary pulp from Fructus Schisandra Chinensis supplementation reduces serum/hepatic lipid and hepatic glucose levels in mice fed a normal or high cholesterol/bile salt diet

Background

Recently, it has been found that Fructus Schisandra Chinensis (FSC), a Chinese herbal medicine, and its related compounds have a profound impact on lipid metabolism process. FSC can be divided into two parts, i.e., seed and pulp. The current study aimed to examine the effect of aqueous extracts of FSC pulp (AqFSC-P) on serum/hepatic lipid and glucose levels in mice fed with a normal diet (ND) or a high cholesterol/bile salt diet (HCBD).

Methods

The AqFSC-P used in the present study was fractionated into supernatant (SAqFSC-P) and precipitate (PAqFSC-P) separated by centrifugation. Male ICR mice were fed with ND or HCBD, without or with supplementation of 1%, 3%, or 9% (w/w) SAqFSC-P or PAqFSC-P for 10 days. Biomarkers were determined according to the manufacturer’s instruction.

Results

Supplementation with SAqFSC-P or PAqFSC-P significantly reduced serum and hepatic triglyceride levels (approximately 40%) in ND- and/or HCBD-fed mice. The supplementation with SAqFSC-P or PAqFSC-P reduced hepatic total cholesterol levels (by 27 - 46%) in HCBD-fed mice. Supplementation with SAqFSC-P or PAqFSC-P markedly lowered hepatic glucose levels (by 13 - 30%) in ND- and HCBD-fed mice. SAqFSC-P decreased serum alanine aminotransferase (ALT) activity, but PAqFSC-P increased hepatic protein contents in ND-fed mice. Bicylol, as a positive control, reduced ALT activity. In addition, mice supplemented with FSC-P or bicylol showed a smaller body weight gain and adipose tissue mass as compared to the respective un-supplemented ND- or HCBD-fed mice.

Conclusion

The results indicate that SAqFSC-P and PAqFSC-P produce hepatic lipid- and glucose-lowering as well as serum TG-lowering effects in hypercholesterolemic mice. FSC pulp may provide a safe alternative for the management of fatty liver and/or lipid disorders in humans.