Expression and Sequence Variants of Inflammatory Genes; Effects on Plasma Inflammation Biomarkers Following a 6-Week Supplementation with Fish Oil

An Exploratory Critical Review on TNF-α as a Potential Inflammatory Biomarker Responsive to Dietary Intervention with Bioactive Foods and Derived Products

This review collects and critically examines data on the levels of tumour necrosis factor-alpha (TNF-α) in lean, overweight and obese subjects, and the effects of intervention with different foods and food products containing bioactive constituents in overweight/obese individuals. We additionally explore the influence of different single nucleotide polymorphisms (SNPs) on TNF-α levels and compare the response to food products with that to some anti-obesity drugs. Our aim was to provide an overview of the variability, consistency, and magnitude of the reported effects of dietary factors on TNF-α, and to envisage the reliability of measuring changes in the levels of this cytokine as a biomarker responsive to food intervention in association with the reduction in body weight. Regarding the circulating levels of TNF-α, we report: (i) a large intra-group variability, with most coefficients of variation (CV%) values being ≥30% and, in many cases, >100%; (ii) a large between-studies variability, with baseline TNF-α values ranging from <1.0 up to several hundred pg/mL; (iii) highly variable effects of the different dietary approaches with both statistically significant and not significant decreases or increases of the protein, and the absolute effect size varying from <0.1 pg/mL up to ≈50 pg/mL. Within this scenario of variability, it was not possible to discern clear differentiating limits in TNF-α between lean, overweight, and obese individuals or a distinct downregulatory effect on this cytokine by any of the different dietary approaches reviewed, i.e., polyunsaturated fatty acids (PUFAs), Vitamin-D (VitD), mixed (micro)nutrients, (poly)phenols or other phytochemicals. Further, there was not a clear relationship between the TNF-α responses and body weight changes. We found similarities between dietary and pharmacological treatments in terms of variability and limited evidence of the TNF-α response. Different factors that contribute to this variability are discussed and some specific recommendations are proposed to reinforce the need to improve future studies looking at this cytokine as a potential biomarker of response to dietary approaches.

Effects of high fat diets and supplemental tart cherry and fish oil on obesity and type 2 diabetes in male and female C57BL/6J and TALLYHO/Jng mice

Obesogenic and diabetogenic high fat (HF) diets can influence genetic factors in disease development with sexual dimorphic responses. We investigated potential protective effects of tart cherry (TC), fish oil (FO) and TC+FO supplementation in TALLYHO/Jng (TH) and C57BL/6J (B6) mice fed HF diets. Male and female TH and B6 mice were weaned onto five different diets; low fat (LF), HF, and HF supplemented with TC, FO, or TC+FO and maintained. For both males and females on LF, TH mice were heavier and fatter than B6, which was accentuated by HF in males, but not in females. TH males, but not others, developed severe glucose intolerance and hyperglycemia on HF, with reduced mRNA levels of Adipoq and Esr1 in adipose tissue. Considering energy balance, locomotor activity was lower in TH mice than B6 for both sexes without diet effects, except B6 females where HF decreased it. Compared to LF, HF decreased energy expenditure, RER, and food intake (in grams) for both sexes without strain differences. In all mice, but B6 males, HF increased plasma IL6 levels compared to LF. No preventive effects of TC, FO or TC+FO were noted for HF-induced obesity or energy imbalance, but FO alleviated glucose intolerance in TH males. Further, TC and FO decreased plasma IL6 levels, especially in females, without additive or synergistic effects of these two. Collectively, obesogenic and diabetogenic impacts of HF diets differed depending on the genetic predisposition. Moreover, sexually dimorphic effects of dietary supplementation were observed for glucose metabolism and inflammatory markers.

Whole Genome Interpretation for a Family of Five

Although best practices have emerged on how to analyse and interpret personal genomes, the utility of whole genome screening remains underdeveloped. A large amount of information can be gathered from various types of analyses via whole genome sequencing including pathogenicity screening, genetic risk scoring, fitness, nutrition, and pharmacogenomic analysis. We recognize different levels of confidence when assessing the validity of genetic markers and apply rigorous standards for evaluation of phenotype associations. We illustrate the application of this approach on a family of five. By applying analyses of whole genomes from different methodological perspectives, we are able to build a more comprehensive picture to assist decision making in preventative healthcare and well-being management. Our interpretation and reporting outputs provide input for a clinician to develop a healthcare plan for the individual, based on genetic and other healthcare data.

Lowering effects of fish oil supplementation on proinflammatory markers in hypertension: results from a randomized controlled trial

Reduced inflammation is one of the potential mechanisms underlying the cardioprotective efficacy of fish oil enriched with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Supplementation with fish oil has favorable effects on cardiometabolic profiles in Inner Mongolia patients with hypertension, but whether the cardiovascular benefits can be ascribed to reduced subclinical inflammation is unclear among this population. Seventy-seven middle-aged/elderly hypertensive volunteers were randomly assigned to receive either fish oil (FO, n = 38, 2 g day-1 EPA + DHA) or control corn oil (CO, n = 39) for 90 days. FA compositions in erythrocytes and C-reactive protein (CRP, mg L-1), interleukin-6 (IL-6, pg mL-1) and tumor necrosis factor-α (TNF-α, pg mL-1) concentrations in the plasma were measured before and after the 90-day supplementation, and the cardiometabolic risk was expressed as continuously distributed z-scores calculated by standardizing and then summing the individual cardiovascular risk factors. Significant reductions in the TNF-α (-1.87 ± 2.71 vs. -0.64 ± 2.62, p = 0.02) and CRP levels (-0.85 ± 2.49 vs. 0.56 ± 2.14, p = 0.01) were found in the FO group compared with the CO group, but not in the IL-6 levels (-0.66 ± 1.05 vs. -0.25 ± 0.94, p = 0.10). The decreases in the changes of TNF-α levels were positively correlated with the reductions in the cardiometabolic risk scores in the subjects supplemented with FO (r = 0.35, p = 0.02), but not in the control subjects supplemented with CO (r = 0.09, p = 0.54). FO supplementation increased the levels of EPA (p = 0.013), DHA (p = 0.040) and total n-3 FA (p = 0.035), and decreased the levels of 20:4n-6 (p = 0.041) and total n-6 FA (p = 0.011) and the ratio of n-6 to n-3 FA (p = 0.001), compared with the changes related to the CO group. The increases in the changes of erythrocyte total n-3 FA levels were inversely correlated with the concentrations of TNF-α (r = -0.34, p = 0.001) and CRP (r = -0.29, p = 0.020). The present findings suggest that fish oil supplementation may attenuate the proinflammatory reactions in hypertension, which might help promote the cardiometabolic benefits in this Inner Mongolia population.

Nutritional genomics, inflammation and obesity

The Human Genome Project has significantly broadened our understanding of the molecular aspects regulating the homeostasis and the pathophysiology of different clinical conditions. Consequently, the field of nutrition has been strongly influenced by such improvements in knowledge - especially for determining how nutrients act at the molecular level in different conditions, such as obesity, type 2 diabetes, cardiovascular disease, and cancer. In this manner, characterizing how the genome influences the diet and vice-versa provides insights about the molecular mechanisms involved in chronic inflammation-related diseases. Therefore, the present review aims to discuss the potential application of Nutritional Genomics to modulate obesity-related inflammatory responses. Arch Endocrinol Metab. 2020;64(3):205-22.

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.

Systemic low-grade inflammation-associated lifestyle, diet, and genetic factors: A population-based cross-sectional study

OBJECTIVES

Systemic low-grade inflammation (SLGI) is an intermediary common condition to the physiopathology of chronic noncommunicable diseases and targeting its determinants could lead to more efficient public health strategies. We aimed to investigate SLGI-independent associations with lifestyle, diet, and genetic factors in a population-based sample of adults using a systemic low-grade inflammation score (SIS).

METHODS

The study sample is composed of 269 participants from the cross-sectional population-based Health Survey of Sao Paulo (2008-2010), ages 20 to 59 y, whose data on socioeconomic variables, lifestyle, health parameters, and blood samples were available. Diet was assessed by two 24-h recalls, and the Brazilian Health Eating Index-Revised (BHEI-R) was scored. From blood samples, 30 single nucleotide polymorphisms on inflammatory genes were genotyped, and plasma eleven inflammatory biomarkers levels that composed the SIS were determined. A multiple, stepwise, linear regression was used to investigate SIS-independent associated factors.

RESULTS

Factors independently associated with SIS were BHEI-R score (partial R² = 5.1; β = -0.13; P = 0.003), body mass index (partial R² = 3.4; β = 0.19; P = 0.001), TLR4 rs5030728 GA + AA genotype (partial R² = 3.1; β = -1.37; P = 0.008), age 50 to 59 y (partial R² = 2.5; β = 1.93; P = 0.029) in comparison with the reference category (20 to 29 y), and commuting physical activity >150 min/wk (partial R² = 2.2; β = -1.29; P = 0.043) after adjustment for current smoking status, medication use, and dietary misreporting.

CONCLUSIONS

Eating a lower quality diet, having a higher body mass index score and age, being GG homozygous for TLR4 rs5030728, and spending <150 min/wk in transportation physical activity are independent determinants of SLGI.

A Genetic Score of Predisposition to Low-Grade Inflammation Associated with Obesity May Contribute to Discern Population at Risk for Metabolic Syndrome

Omega-3 rich diets have been shown to improve inflammatory status. However, in an ex vivo system of human blood cells, the efficacy of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) modulating lipid metabolism and cytokine response is attenuated in overweight subjects and shows high inter-individual variability. This suggests that obesity may be exerting a synergistic effect with genetic background disturbing the anti-inflammatory potential of omega-3 long-chain polyunsaturated fatty acids (PUFA). In the present work, a genetic score aiming to explore the risk associated to low grade inflammation and obesity (LGI-Ob) has been elaborated and assessed as a tool to contribute to discern population at risk for metabolic syndrome. Pro-inflammatory gene expression and cytokine production as a response to omega-3 were associated with LGI-Ob score; and lower anti-inflammatory effect of PUFA was observed in subjects with a high genetic score. Furthermore, overweight/obese individuals showed positive correlation of both plasma C-Reactive Protein and triglyceride/HDLc-index with LGI-Ob; and high LGI-Ob score was associated with greater hypertension (p = 0.047), Type 2 diabetes (p = 0.026), and metabolic risk (p = 0.021). The study shows that genetic variation can influence inflammation and omega-3 response, and that the LGI-Ob score could be a useful tool to classify subjects at inflammatory risk and more prone to suffer metabolic syndrome and associated metabolic disturbances.

Assessment of Dietary Patterns Represents a Potential, Yet Variable, Measure of Inflammatory Status: A Review and Update

Chronic low-grade, systemic inflammation is a well-characterized risk factor in the development of chronic metabolic diseases, such as cardiovascular disease, type 2 diabetes, and metabolic syndrome. Diet could be an effective strategy for reducing inflammation associated with chronic disease. While anti-inflammatory properties of isolated dietary bioactive and functional foods have been routinely studied, the evaluation of dietary patterns on inflammation warrants further review-especially given the recent inclusion of dietary pattern recommendations into dietary guidelines and policies. Therefore, the objective of this narrative review is to examine current evidence linking diet to low-grade, systemic inflammation within the context of chronic disease. Specifically, we provide an update on the findings from human trials that have characterized anti-inflammatory properties of dietary patterns, defined by various methods and indexes. Given the complexity of interpreting results from dietary pattern analysis, we further present recent evidence on the anti-inflammatory roles of isolated bioactive nutrients and functional foods that are common components of distinct dietary patterns, in addition to considerations for interpreting dietary pattern research, population-specific dietary recommendations, and future studies. Overall, we observe a vast range of variability in the evidence from observational studies that have evaluated the relationships between healthy dietary patterns and inflammatory markers. These studies highlight the need for additional intervention studies with study designs that account for metabolic status, diversity in populations, breadth of inflammatory measurements, fasting vs. postprandial effects of diet, and control of confounding factors (e.g., genotype, microbiome profiles, and dietary adherence) in order to better understand the effect that diet has, as a whole, on inflammation. These strategies will help to strengthen diet recommendations aimed at reducing inflammation and chronic disease risk.

A Randomized Double-Blinded, Placebo-Controlled Trial Investigating the Effect of Fish Oil Supplementation on Gene Expression Related to Insulin Action, Blood Lipids, and Inflammation in Gestational Diabetes Mellitus-Fish Oil Supplementation and Gestational Diabetes

Gestational diabetes mellitus (GDM) is a common complication of pregnancy, and it is mostly associated with postpartum diabetes, insulin resistance, and dyslipidemia. Fish oil (omega-3) supplementation has been shown to reduce the risk of different chronic diseases such as cardiovascular disease, type 2 diabetes, and cancers, though the evidence of its impact on gestational diabetes is scarce. Our goal in this study was to determine the effect of fish oil administration on gene expression related to insulin action, blood lipids, and inflammation in women with GDM. Participants with GDM (n = 40), aged 18–40 years, were randomized to take either 1000 mg fish oil capsules, containing 180 mg eicosapentaenoic acid and 120 mg docosahexaenoic acid (n = 20), or placebo (n = 20) twice a day for 6 weeks. Gene expression related to insulin, lipids, and inflammation was quantified in peripheral blood mononuclear cells (PBMCs) of GDM women using Reverse Transcription Polymerase Chain Reaction (RT-PCR) method. Results of RT-PCR indicated that omega-3 supplementation upregulated gene expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) (P = 0.04) in PBMCs of patients with GDM, compared with the placebo. In addition, gene expression of the low-density lipoprotein receptor (LDLR) (P < 0.001), interleukin-1 (IL-1) (P = 0.007), and tumor necrosis factor alpha (TNF-α) (P = 0.01) was downregulated in PBMCs of women with GDM, following omega-3 supplementation. No significant effect of omega-3 supplementation was indicated on gene expression of IL-8 in PBMCs of patients with GDM. Overall, fish oil supplementation for 6 weeks in women with GDM significantly improved gene expression of PPAR-γ, IL-1, and TNF-α, but not gene expression of IL-8.

Neuroinflammation in Autism: Plausible Role of Maternal Inflammation, Dietary Omega 3, and Microbiota

Several genetic causes of autism spectrum disorder (ASD) have been identified. However, more recent work has highlighted that certain environmental exposures early in life may also account for some cases of autism. Environmental insults during pregnancy, such as infection or malnutrition, seem to dramatically impact brain development. Maternal viral or bacterial infections have been characterized as disruptors of brain shaping, even if their underlying mechanisms are not yet fully understood. Poor nutritional diversity, as well as nutrient deficiency, is strongly associated with neurodevelopmental disorders in children. For instance, imbalanced levels of essential fatty acids, and especially polyunsaturated fatty acids (PUFAs), are observed in patients with ASD and other neurodevelopmental disorders (e.g., attention deficit hyperactivity disorder (ADHD) and schizophrenia). Interestingly, PUFAs, and specifically n-3 PUFAs, are powerful immunomodulators that exert anti-inflammatory properties. These prenatal dietary and immunologic factors not only impact the fetal brain, but also affect the microbiota. Recent work suggests that the microbiota could be the missing link between environmental insults in prenatal life and future neurodevelopmental disorders. As both nutrition and inflammation can massively affect the microbiota, we discuss here how understanding the crosstalk between these three actors could provide a promising framework to better elucidate ASD etiology.

Effectiveness of Omega-3 Polyunsaturated Fatty Acids in Non-Alcoholic Fatty Liver Disease: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a clinical syndrome with the main characteristic of diffuse liver cells with fatty changes. The clinical evolution of NAFLD includes simple non-alcoholic fatty liver, non-alcoholic steatohepatitis (NASH), liver fibrosis and cirrhosis, and even hepatocellular carcinoma.

METHODS AND FINDINGS

We conducted this review to identify the effectiveness of omega-3 polyunsaturated fatty acids (ω-3 PUFA) in NAFLD. We searched PubMed, Cochrane Library and Embase. All randomized controlled trials (RCTs) of ω-3 PUFA treatment for NAFLD were considered. Two reviewers assessed the quality of each study and collected data independently. Disagreements were resolved by discussion among the reviewers and any of the other authors of the paper. We performed a meta-analysis and reported summary estimates of outcomes as inverse variance (IV), fixed or random, with 95% confidence intervals (CIs). We included seven RCTs involving 442 patients (227 for the experimental group and 215 for the control group). All the patients were divided into two groups: one treated with ω-3 PUFA and the other was the control group (generally placebo). The demographics of the ω-3 PUFA and control groups were comparable. Beneficial changes in alanine aminotransferase (ALT) (IV 95% CI: -7.61 [-12.83 to -2.39], p = 0.004), total cholesterol (TC) (IV 95% CI: -13.41 [-21.44 to -5.38], p = 0.001), triglyceride (TG) (IV 95% CI: -43.96 [-51.21 to -36.71], p<0.00001) and high-density lipoprotein cholesterol (HDL-C) (IV 95% CI: 6.97 [2.05 to 11.90], p = 0.006) favored ω-3 PUFA treatment. Omega-3 PUFA tended towards a beneficial effect on aspartate aminotransferase (AST) (IV 95% CI: -6.89 [-17.71 to 3.92], p = 0.21), γ-glutamyl transferase (GGT) (IV 95% CI: -8.28 [-18.38 to 1.83], p = 0.11) and low-density lipoprotein cholesterol (LDL-C) (IV 95% CI: -7.13 [-14.26 to 0.0], p = 0.05).

CONCLUSIONS

Supplementation with ω-3 PUFA is a practical and effective treatment for NAFLD to decrease ALT, TC and increase HDL-C, especially to decrease TG. Omega-3 PUFA also has a tendency toward a beneficial effect on AST, GGT and LDL-C. More high-quality, large RCTs are needed to validate our findings.