Differences in peripheral blood mononuclear cell gene expression and triglyceride composition in lipoprotein subclasses in plasma triglyceride responders and non-responders to omega-3 supplementation

Fish Oil Derivatives in Hypertriglyceridemia: Mechanism and Cardiovascular Prevention: What Do Studies Say?

Hypertriglyceridemia is a type of dyslipidemia characterized by high triglyceride levels in the blood and increases the risk of cardiovascular disease. Conventional management includes antilipidemic medications such as statins, lowering LDL and triglyceride levels as well as raising HDL levels. However, the treatment may be stratified using omega-3 fatty acid supplements such as eicosatetraenoic acid (EPA) and docosahexaenoic acid (DHA), aka fish oil derivatives. Studies have shown that fish oil supplements reduce the risk of cardiovascular diseases; however, the underlying mechanism and the extent of reduction in CVD need more clarification. Our paper aims to review the clinical trials and observational studies in the current literature, investigating the use of fish oil and its benefits on the cardiovascular system as well as the proposed underlying mechanism.

Variability in the Clinical Effects of the Omega-3 Polyunsaturated Fatty Acids DHA and EPA in Cardiovascular Disease-Possible Causes and Future Considerations

Cardiovascular disease (CVD) that includes myocardial infarction and stroke, is the leading cause of mortality worldwide. Atherosclerosis, the primary underlying cause of CVD, can be controlled by pharmacological and dietary interventions, including n-3 polyunsaturated fatty acid (PUFA) supplementation. n-3 PUFA supplementation, primarily consisting of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has shown promise in reducing atherosclerosis by modulating risk factors, including triglyceride levels and vascular inflammation. n-3 PUFAs act by replacing pro-inflammatory fatty acid types in cell membranes and plasma lipids, by regulating transcription factor activity, and by inducing epigenetic changes. EPA and DHA regulate cellular function through shared and differential molecular mechanisms. Large clinical studies on n-3 PUFAs have reported conflicting findings, causing confusion among the public and health professionals. In this review, we discuss important factors leading to these inconsistencies, in the context of atherosclerosis, including clinical study design and the differential effects of EPA and DHA on cell function. We propose steps to improve clinical and basic experimental study design in order to improve supplement composition optimization. Finally, we propose that understanding the factors underlying the poor response to n-3 PUFAs, and the development of molecular biomarkers for predicting response may help towards a more personalized treatment.

Omega-3 fatty acids and individual variability in plasma triglyceride response: A mini-review

Cardiovascular disease (CVD) is a leading cause of death worldwide. Supplementation with the marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is associated with lower CVD risk. However, results from randomized controlled trials that examine the effect of omega-3 supplementation on CVD risk are inconsistent. This risk-reducing effect may be mediated by reducing inflammation, oxidative stress and serum triglyceride (TG) levels. However, not all individuals respond by reducing TG levels after omega-3 supplementation. This inter-individual variability in TG response to omega-3 supplementation is not fully understood. Hence, we aim to review the evidence for how interactions between omega-3 fatty acid supplementation and genetic variants, epigenetic and gene expression profiling, gut microbiota and habitual intake of omega-3 fatty acids can explain why the TG response differs between individuals. This may contribute to understanding the current controversies and play a role in defining future personalized guidelines to prevent CVD.

Clinical Practice Guidelines Using GRADE and AGREE II for the Impact of Genetic Variants on Plasma Lipid/Lipoprotein/Apolipoprotein Responsiveness to Omega-3 Fatty Acids

Background

A recent systematic review, which used the GRADE methodology, concluded that there is strong evidence for two gene-diet associations related to omega-3 and plasma triglyceride (TG) responses. Systematic reviews can be used to inform the development of clinical practice guidelines (CPGs).

Objective

To provide guidance for clinical practice related to genetic testing for evaluating responsiveness to dietary/supplemental omega-3s and their impact on plasma lipids/lipoproteins/apolipoproteins.

Design

Using the results of the abovementioned systematic review, the first CPGs in nutrigenetics were developed using the established GRADE methodology and AGREE II approach.

Results

Three clinical practice recommendations were developed. Most gene-diet associations identified in the literature lack adequate scientific and clinical validity to warrant consideration for implementing in a practice setting. However, two gene-diet associations with strong evidence (GRADE quality: moderate and high) can be considered for implementation into clinical practice in certain cases: male APOE-E4 carriers (rs429358, rs7412) and TG changes in response to the omega-3 fatty acids eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) as well as a 31-SNP nutrigenetic risk score and TG changes in response to EPA+DHA among adults with overweight/obesity. Ethical and regulatory implications must be considered when providing APOE nutrigenetic tests given the well-established link between APOE genetic variation and Alzheimer's Disease.

Conclusion

Most of the evidence in this area is not ready for implementation into clinical practice primarily due to low scientific validity (low quality of evidence). However, the first CPGs in nutrigenetics have been developed for two nutrigenetic associations with strong scientific validity, related to dietary/supplemental omega-3 and TG responses.

Artichoke and Bergamot Phytosome Alliance: A Randomized Double Blind Clinical Trial in Mild Hypercholesterolemia

Botanicals are natural alternatives to pharmacological therapies that aim at reducing hypercholesterolemia. In this context, despite bergamot being effective in modulating lipid profile, some subjects failed to achieve a satisfactory response to supplementation. The aim of this study was to evaluate whether the association of 600 mg of bergamot phytosome^® (from Citrus Bergamia Risso) and 100 mg of artichoke leaf standardized dry extract (from Cynara cardunculus L.) can be an alternative in patients with mild hypercholesterolemia who are poor responders to bergamot in a 2-month randomized placebo-controlled trial. Sixty overweight adults were randomized into two groups: 30 were supplemented and 30 received a placebo. The metabolic parameters and DXA body composition were evaluated at the start, after 30 and 60 days. Between the two groups, total and LDL cholesterol in the supplemented group (compared to placebo) showed significant decreases overtime. A significant reduction of waist circumference and visceral adipose tissue (VAT) was recorded in the supplemented group (compared to placebo), even in subjects who did not follow a low-calorie diet. In conclusion, the synergism between Citrus Bergamia polyphenols and Cynara cardunculus extracts may be an effective option and may potentially broaden the therapeutic role of botanicals in dyslipidemic patients.

Dietary Fatty Acids at the Crossroad between Obesity and Colorectal Cancer: Fine Regulators of Adipose Tissue Homeostasis and Immune Response

Colorectal cancer (CRC) is among the major threatening diseases worldwide, being the third most common cancer, and a leading cause of death, with a global incidence expected to increase in the coming years. Enhanced adiposity, particularly visceral fat, is a major risk factor for the development of several tumours, including CRC, and represents an important indicator of incidence, survival, prognosis, recurrence rates, and response to therapy. The obesity-associated low-grade chronic inflammation is thought to be a key determinant in CRC development, with the adipocytes and the adipose tissue (AT) playing a significant role in the integration of diet-related endocrine, metabolic, and inflammatory signals. Furthermore, AT infiltrating immune cells contribute to local and systemic inflammation by affecting immune and cancer cell functions through the release of soluble mediators. Among the factors introduced with diet and enriched in AT, fatty acids (FA) represent major players in inflammation and are able to deeply regulate AT homeostasis and immune cell function through gene expression regulation and by modulating the activity of several transcription factors (TF). This review summarizes human studies on the effects of dietary FA on AT homeostasis and immune cell functions, highlighting the molecular pathways and TF involved. The relevance of FA balance in linking diet, AT inflammation, and CRC is also discussed. Original and review articles were searched in PubMed without temporal limitation up to March 2021, by using fatty acid as a keyword in combination with diet, obesity, colorectal cancer, inflammation, adipose tissue, immune cells, and transcription factors.

Omega-3 PUFA Responders and Non-Responders and the Prevention of Lipid Dysmetabolism and Related Diseases

The long-chain omega-3 polyunsaturated fatty acids (LC-omega-3 PUFAs) eicosapentaenoic acid and docosahexaenoic acid are the most popular dietary supplements recommended for the prevention/management of lipid dysmetabolisms and related diseases. However, remarkable inconsistencies exist among the outcomes of the human intervention studies in this field, which contrast with the impressive homogeneity of positive results of most of the preclinical studies. In the present review, we will firstly examine a series of factors-such as background diet composition, gut microbiota and genetic/epigenetic variants, which may lie beneath these inconsistencies. Moreover, we will discuss the recent advance in the knowledge of possible specific biomarkers (genetic-, epigenetic- and microbiota-related) that are being investigated with the goal to apply them in a personalized supplementation with omega-3 PUFAs. We will also consider the possibility of using already available parameters (Omega-3 index, Omega-6 PUFA/Omega-3 PUFA ratio) able to predict the individual responsiveness to these fatty acids and will discuss the optimal timing for their use. Finally, we will critically examine the results of those human studies that have already adopted the distinction of the subjects into omega-3 PUFA responders and non-responders and will discuss the advantage of using such an approach.

Metabolomic and gene expression analysis to study the effects of dietary saturated and polyunsaturated fats

PURPOSE OF REVIEW

Give an update on recent dietary intervention studies that have used peripheral blood mononuclear cell gene expression analysis and/or metabolic profiling to understand how intake of polyunsaturated and saturated fat affects and biological pathways linked to cardiovascular disease.

RECENT FINDINGS

Several studies showed that intake of fish oil and vegetable oil, high in omega-3 fatty acids, reduced expression level of genes involved in inflammation. One intervention study showed that gene transcripts encoding genes involved inflammation and lipid metabolism increased after intake of polyunsaturated fat (mainly omega-6 fatty acids) compared to saturated fat. Additionally, using targeted metabolomics, the concentrations of atherogenic lipoprotein particles and several metabolites including palmitoylcarnitine, myristoylcarnitine, and kynurenine were reduced after intake of polyunsaturated fat compared to saturated fat, whereas acetate and acetoacetate were increased. The use of targeted metabolomics showed that overfeeding with polyunsaturated fat reduced the serum concentration of ceramides, dihydroceramides, glucosylceramides, and lactosylceramides, whereas overfeeding with saturated fat increased serum concentration of these metabolites.

SUMMARY

The use of gene expression profiling and metabolomics are promising tools to identify possible new biomarkers linking fat quality to cardiovascular disease risk.

CoMM: A Collaborative Mixed Model That Integrates GWAS and eQTL Data Sets to Investigate the Genetic Architecture of Complex Traits

Genome-wide association study (GWAS) analyses have identified thousands of associations between genetic variants and complex traits. However, it is still a challenge to uncover the mechanisms underlying the association. With the growing availability of transcriptome data sets, it has become possible to perform statistical analyses targeted at identifying influential genes whose expression levels correlate with the phenotype. Methods such as PrediXcan and transcriptome-wide association study (TWAS) use the transcriptome data set to fit a predictive model for gene expression, with genetic variants as covariates. The gene expression levels for the GWAS data set are then 'imputed' using the prediction model, and the imputed expression levels are tested for their association with the phenotype. These methods fail to account for the uncertainty in the GWAS imputation step, and we propose a collaborative mixed model (CoMM) that addresses this limitation by jointly modelling the multiple analysis steps. We illustrate CoMM's ability to identify relevant genes in the Northern Finland Birth Cohort 1966 data set and extend the model to handle the more widely available GWAS summary statistics.

Personalised nutrition - phenotypic and genetic variation in response to dietary intervention

Personalised nutrition allows individual differences in dietary, lifestyle, anthropometry, phenotype and/or genomic profile to be used to direct specific dietary advice. For personalised nutrition advice to be effective both sides need to be considered; firstly, that factors influencing variation in response to dietary intervention are identified and appropriate advice can be derived and secondly; that these are then used effectively in the provision of nutrition advice, resulting in a positive dietary and/or lifestyle behaviour change. There is considerable evidence demonstrating genetic and phenotypic influence on the biological response to the consumption of nutrients and bioactives. However, findings are often mixed, with studies often investigating at the level of a single nutrient/bioactive and/or a single genetic/phenotypic variation, meaning the derivation of specific advice at a dietary level in an individual/group of individuals can be complex. Similarly, the impact of using this information to derive personalised advice is also mixed, with some studies demonstrating no effectiveness and others showing a significant impact. The present paper will outline examples of phenotypic and genetic variation influencing response to nutritional interventions, and will consider how they could be used in the provision of personalised nutrition.