Lydia A. Afman

Fish-oil supplementation induces antiinflammatory gene expression profiles in human blood mononuclear cells

BACKGROUND Polyunsaturated fatty acids can have beneficial effects on human immune cells, such as peripheral blood mononuclear cells (PBMCs). However, the mechanisms of action of polyunsaturated fatty acids on immune cells are still largely unknown. OBJECTIVE The objective was to examine the effects of supplementation with the polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on whole-genome PBMC gene expression profiles, in healthy Dutch elderly subjects participating in a double-blind trial, by using whole-genome transcriptomics analysis. DESIGN The subjects were randomly allocated to 1 of 3 groups: 1) consumption of 1.8 g EPA+DHA/d (n = 36), 2) consumption of 0.4 g EPA+DHA/d (n = 37), or 3) consumption of 4.0 g high-oleic acid sunflower oil (HOSF)/d (n = 38). All supplements were given in capsules. Before and after 26 wk of intervention, blood samples were collected. Microarray analysis was performed on PBMC RNA from 23 subjects who received 1.8 g EPA+DHA/d and 25 subjects who received HOSF capsules. Quantitative real-time polymerase chain reaction was performed in all 111 subjects. RESULTS A high EPA+DHA intake changed the expression of 1040 genes, whereas HOSF intake changed the expression of only 298 genes. EPA+DHA intake resulted in a decreased expression of genes involved in inflammatory- and atherogenic-related pathways, such as nuclear transcription factor kappaB signaling, eicosanoid synthesis, scavenger receptor activity, adipogenesis, and hypoxia signaling. CONCLUSION These results are the first to show that intake of EPA+DHA for 26 wk can alter the gene expression profiles of PBMCs to a more antiinflammatory and antiatherogenic status. This trial was registered at clinicaltrials.gov as NCT00124852.

Postprandial dietary lipid–specific effects on human peripheral blood mononuclear cell gene expression profiles

BACKGROUND Dietary polyunsaturated fatty acids (PUFAs) have a variety of beneficial effects, and immune cells play an important role in these effects. The mechanisms of action of PUFAs are still not completely understood, but it is known that PUFAs can influence the expression of a broad set of genes. OBJECTIVE The objective was to determine the postprandial effects of intake of different fatty acids on the gene expression profiles of peripheral blood mononuclear cells (PBMCs). DESIGN In a single-blind crossover study, 21 healthy male volunteers consumed shakes enriched in PUFAs, monounsaturated fatty acids (MUFAs), or saturated fatty acids (SFAs) in random order. Blood samples were collected before and at several time points after intake. Whole-genome gene expression profiles of PBMCs were examined before and 6 h after intake of the PUFA and SFA shakes. In addition, ex vivo incubation of human PBMCs with different fatty acids was performed. RESULTS Whole-genome expression analysis showed distinct differences between PUFA and SFA consumption. PUFA intake decreased the expression of genes in liver X receptor signaling, whereas SFA intake increased the expression of these genes. PUFA intake also increased the expression of genes related to cellular stress responses. MUFA intake had an intermediate effect on several genes. Ex vivo experiments showed a direct effect of free fatty acids on PBMC gene expression. CONCLUSION This study showed that PBMCs can reveal fatty acid-specific gene expression profiles in young healthy men after the consumption of different fatty acids, as evidenced by the opposite effects of PUFA and SFA intakes on the expression of genes involved in liver X receptor signaling. This trial was registered at www.clinicaltrials.gov as NCT01000194.

Phenotyping the effect of diet on non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is associated with the growing incidence of metabolic syndrome. Diet is an important contributor to the pathogenesis of NAFLD. In this review, we focused on recent publications reporting on the effect of macro- and micronutrients on development and progression of NAFLD. In general, saturated fat and fructose seem to stimulate hepatic lipid accumulation and progression into NASH, whereas unsaturated fat, choline, antioxidants, and high-protein diets rich in isoflavones seem to have a more preventive effect. Knowledge of the underlying mechanisms by which diet affects NAFLD is expanding, not in the least due to innovative techniques, such as genomics tools that provide detailed comprehensive information on a large high-throughput scale. Although most nutrients seem to interfere with the balance between hepatic de novo lipogenesis (endogenous synthesis of fatty acids) and lipid oxidation (burning fat for energy), there are also indications that diet can trigger or prevent hepatic lipid accumulation by influencing the interaction between liver, gut, and adipose tissue. This review now gives a current detailed overview of diet-mediated mechanisms underlying NAFLD development and progression and summarizes recent results of genomics (transcriptomics, proteomics and metabolomics) studies that contribute to improved staging, monitoring and understanding of NAFLD pathophysiology.

The effects of 30 days resveratrol supplementation on adipose tissue morphology and gene expression patterns in obese men

Polyphenolic compounds, such as resveratrol, have recently received widespread interest because of their ability to mimic effects of calorie restriction. The objective of the present study was to gain more insight into the effects of 30 days resveratrol supplementation on adipose tissue morphology and underlying processes. Eleven healthy obese men were supplemented with placebo and resveratrol for 30 days (150 mg per day), separated by a 4-week washout period in a double-blind randomized crossover design. A postprandial abdominal subcutaneous adipose tissue biopsy was collected to assess adipose tissue morphology and gene expression using microarray analysis. Resveratrol significantly decreased adipocyte size, with a shift toward a reduction in the proportion of large and very-large adipocytes and an increase in small adipocytes. Microarray analysis revealed downregulation of Wnt and Notch signaling pathways and upregulation of pathways involved in cell cycle regulation after resveratrol supplementation, suggesting enhanced adipogenesis. Furthermore, lysosomal/phagosomal pathway and transcription factor EB were upregulated reflecting an alternative pathway of lipid breakdown by autophagy. Further research is necessary to investigate whether resveratrol improves adipose tissue function.

Human nutrigenomics of gene regulation by dietary fatty acids

Nutrigenomics employs high-throughput genomics technologies to unravel how nutrients modulate gene and protein expression and ultimately influence cellular and organism metabolism. The most often-applied genomics technique so far is transcriptomics, which allows quantifying genome-wide changes in gene expression of thousands of genes at the same time in one sample. The performance of gene expression quantification requires sufficient high-quality homogenous cellular material, therefore research in healthy volunteers is restricted to biopsies from easy accessible tissues such as subcutaneous adipose tissue, skeletal muscle and intestinal biopsies or even more easily accessible cells such as peripheral blood mononuclear cells from blood. There is now significant evidence that fatty acids, in particular unsaturated fatty acids, exert many of their effects through modulation of gene transcription by regulating the activity of numerous transcription factors, including nuclear receptors such as peroxisome proliferator activated receptors, liver X receptor and sterol regulatory binding proteins. This review evaluates the human nutrigenomics studies performed on dietary fat since the initiation of nutrigenomics research around 10 years ago. Although the number of studies is still limited, all studies clearly suggest that changes in dietary fatty acids intake and composition can have a significant impact on cellular adaptive response capacity by gene transcription changes in humans. This adds important knowledge to our understanding of the strong effects that various fatty acids can have on numerous metabolic and inflammatory pathways, signaling routes and homeostatic control in the cell and ultimately on whole body health. It is important to use and integrate nutrigenomics in all future nutrition studies to build up the necessary framework for evidence-based nutrition in near future.

Consumption of a High Monounsaturated Fat Diet Reduces Oxidative Phosphorylation Gene Expression in Peripheral Blood Mononuclear Cells of Abdominally Overweight Men and Women

The Mediterranean (MED) diet is often considered health-promoting due to its high content of MUFA and polyphenols. These bioactive compounds can affect gene expression and accordingly may regulate pathways and proteins related to cardiovascular disease prevention. This study aimed to identify the effects of a MED-type diet, and the replacement of SFA with MUFA in a Western-type diet, on peripheral blood mononuclear cell (PBMC) gene expression and plasma proteins. Abdominally overweight men and women (waist: women ≥80 cm, men ≥94 cm) were allocated to an 8-wk, completely controlled SFA diet (19% daily energy as SFA), a MUFA diet (20% daily energy MUFA), or a MED diet (21% daily energy MUFA). Concentrations of 124 plasma proteins and PBMC whole-genome transcriptional profiles were assessed. Consumption of the MUFA and MED diets, compared with the SFA diet, decreased the expression of oxidative phosphorylation (OXPHOS) genes, plasma connective tissue growth factor, and apoB concentrations. Compared with the MED and SFA diets, the MUFA diet changed the expression of genes involved in B-cell receptor signaling and endocytosis signaling. Participants who consumed the MED diet had lower concentrations of proinflammatory proteins at 8 wk compared with baseline. We hypothesize that replacement of SFA with MUFA may improve health, thereby reducing metabolic stress and OXPHOS activity in PBMC. The MED diet may have additional antiatherogenic effects by lowering proinflammatory plasma proteins.

Activation of peroxisome proliferator-activated receptor alpha in human peripheral blood mononuclear cells reveals an individual gene expression profile response

BackgroundPeripheral blood mononuclear cells (PBMCs) are relatively easily obtainable cells in humans. Gene expression profiles of PBMCs have been shown to reflect the pathological and physiological state of a person. Recently, we showed that the nuclear receptor peroxisome proliferator-activated receptor alpha (PPARα) has a functional role in human PBMCs during fasting. However, the extent of the role of PPARα in human PBMCs remains unclear. In this study, we therefore performed gene expression profiling of PBMCs incubated with the specific PPARα ligand WY14,643.ResultsIncubation of PBMCs with WY14,643 for 12 hours resulted in a differential expression of 1,373 of the 13,080 genes expressed in the PBMCs. Gene expression profiles showed a clear individual response to PPARα activation between six healthy human blood donors. Pathway analysis showed that genes in fatty acid metabolism, primarily in β-oxidation were up-regulated upon activation of PPARα with WY14,643, and genes in several amino acid metabolism pathways were down-regulated.ConclusionThis study shows that PPARα in human PBMCs regulates fatty acid and amino acid metabolism. In addition, PBMC gene expression profiles show individual responses to WY14,643 activation. We showed that PBMCs are a suitable model to study changes in PPARα activation in healthy humans.

Responses to High-Fat Challenges Varying in Fat Type in Subjects with Different Metabolic Risk Phenotypes: A Randomized Trial

Background The ability of subjects to respond to nutritional challenges can reflect the flexibility of their biological system. Nutritional challenge tests could be used as an indicator of health status but more knowledge on metabolic and immune responses of different subjects to nutritional challenges is needed. The aim of this study was to compare the responses to high-fat challenges varying in fat type in subjects with different metabolic risk phenotypes. Methodology/Principal Findings In a cross-over design 42 men (age 50–70 y) consumed three high-fat shakes containing saturated fat (SFA), monounsaturated fat (MUFA) or n-3 polyunsaturated (PUFA). Men were selected on BMI and health status (lean, obese or obese diabetic) and phenotyped with MRI for adipose tissue distribution. Before and 2 and 4 h after shake consumption blood was drawn for measurement of expression of metabolic and inflammation-related genes in peripheral blood mononuclear cells (PBMCs), plasma triglycerides (TAG), glucose, insulin, cytokines and ex vivo PBMC immune response capacity. The MUFA and n-3 PUFA challenge, compared to the SFA challenge, induced higher changes in expression of inflammation genes MCP1 and IL1β in PBMCs. Obese and obese diabetic subjects had different PBMC gene expression and metabolic responses to high-fat challenges compared to lean subjects. The MUFA challenge induced the most pronounced TAG response, mainly in obese and obese diabetic subjects. Conclusion/Significance The PBMC gene expression response and metabolic response to high-fat challenges were affected by fat type and metabolic risk phenotype. Based on our results we suggest using a MUFA challenge to reveal differences in response capacity of subjects. Trial Registration ClinicalTrials.gov NCT00977262

Nutritional aspects of metabolic inflammation in relation to health--insights from transcriptomic biomarkers in PBMC of fatty acids and polyphenols.

Recent research has highlighted potential important interaction between metabolism and inflammation, within the context of metabolic health and nutrition, with a view to preventing diet-related disease. In addition to this, there is a paucity of evidence in relation to accurate biomarkers that are capable of reflecting this important biological interplay or relationship between metabolism and inflammation, particularly in relation to diet and health. Therefore the objective of this review is to highlight the potential role of transcriptomic approaches as a tool to capture the mechanistic basis of metabolic inflammation. Within this context, this review has focused on the potential of peripheral blood mononuclear cells transcriptomic biomarkers, because they are an accessible tissue that may reflect metabolism and subacute chronic inflammation. Also these pathways are often dysregulated in the common diet-related diseases obesity, type 2 diabetes, and cardiovascular disease, thus may be used as markers of systemic health. The review focuses on fatty acids and polyphenols, two classes of nutrients/nonnutrient food components that modulate metabolism/inflammation, which we have used as an example of a proof-of-concept with a view to understanding the extent to which transcriptomic biomarkers are related to nutritional status and/or sensitive to dietary interventions. We show that both nutritional components modulate inflammatory markers at the transcriptomic level with the capability of profiling pro- and anti-inflammatory mechanisms in a bidirectional fashion; to this end transcriptomic biomarkers may have potential within the context of metabolic inflammation. This transcriptomic biomarker approach may be a sensitive indicator of nutritional status and metabolic health.

PUFAs acutely affect triacylglycerol-derived skeletal muscle fatty acid uptake and increase postprandial insulin sensitivity

BACKGROUND Dietary fat quality may influence skeletal muscle lipid processing and fat accumulation, thereby modulating insulin sensitivity. OBJECTIVE The objective was to examine the acute effects of meals with various fatty acid (FA) compositions on skeletal muscle FA processing and postprandial insulin sensitivity in obese, insulin-resistant men. DESIGN In a single-blind, randomized, crossover study, 10 insulin-resistant men consumed 3 high-fat mixed meals (2.6 MJ), which were high in SFAs, MUFAs, or PUFAs. Fasting and postprandial skeletal muscle FA processing was examined by measuring differences in arteriovenous concentrations across the forearm muscle. [²H₂]Palmitate was infused intravenously to label endogenous triacylglycerol and FFAs in the circulation, and [U-¹³C]palmitate was added to the meal to label chylomicron-triacylglycerol. Skeletal muscle biopsy samples were taken to assess intramuscular lipid metabolism and gene expression. RESULTS Insulin and glucose responses (AUC) after the SFA meal were significantly higher than those after the PUFA meal (P = 0.006 and 0.033, respectively). Uptake of triacylglycerol-derived FAs was lower in the postprandial phase after the PUFA meal than after the other meals (AUC₆₀₋₂₄₀; P = 0.02). The fractional synthetic rate of the triacylglycerol, diacylglycerol, and phospholipid pool was higher after the MUFA meal than after the SFA meal. PUFA induced less transcriptional downregulation of oxidative pathways than did the other meals. CONCLUSION PUFAs reduced triacylglycerol-derived skeletal muscle FA uptake, which was accompanied by higher postprandial insulin sensitivity, a more transcriptional oxidative phenotype, and altered intramyocellular lipid partitioning and may therefore be protective against the development of insulin resistance.