Plasma fatty acid levels and gene expression related to lipid metabolism in peripheral blood mononuclear cells: a cross-sectional study in healthy subjects

Variation of LDL cholesterol in response to the replacement of saturated with unsaturated fatty acids: a nonrandomized, sequential dietary intervention; the Reading, Imperial, Surrey, Saturated fat Cholesterol Intervention ("RISSCI"-1) study

BACKGROUND

Serum low density lipoprotein (LDL) cholesterol shows marked interindividual variation in response to the replacement of saturated fatty acids (SFAs) with unsaturated fatty acids (UFAs).

OBJECTIVES

To demonstrate the efficacy of United Kingdom guidelines for exchanging dietary SFAs for UFAs, to reduce serum LDL cholesterol and other cardiovascular disease (CVD) risk factors, and to identify determinants of the variability in LDL cholesterol response.

METHODS

Healthy males (n = 109, mean ± SD age 48 ± 11 y; BMI 25.1 ± 3.3 kg/m2), consumed a higher-SFA/lower-UFA diet for 4 wk, followed by an isoenergetic, lower-SFA/higher-UFA diet for 4 wk (achieved intakes SFA:UFA as % total energy 19.1:14.8 and 8.9:24.5, respectively). Serum LDL cholesterol, CVD risk markers, peripheral blood mononuclear cell (PBMC) gene expression, and dietary intakes were assessed at baseline and the end of each diet.

RESULTS

Transition from a higher-SFA/lower-UFA to a lower-SFA/higher-UFA diet significantly reduced fasting blood lipids: LDL cholesterol (-0.50 mmol/L; 95% confidence interval [CI]: -0.58, -0.42), high-density lipoprotein (HDL) cholesterol (-0.11 mmol/L; 95% CI: -0.14, -0.08), and total cholesterol (TC) (-0.65 mmol/L; 95% CI:-0.75, -0.55). The dietary exchange also reduced apolipoprotein (apo)B, TC:HDL cholesterol ratio, non-HDL cholesterol, E-selectin (P < 0.0001), and LDL subfraction composition (cholesterol [LDL-I and LDL-II], apoB100 [LDL-I and LDL-II], and TAG [LDL-II]) (P < 0.01). There was also an increase in plasma biomarkers of cholesterol intestinal absorption (β-sitosterol, campesterol, cholestanol), and synthesis (desmosterol) (P < 0.0001) and fold change in PBMC LDL-receptor mRNA expression relative to the higher-SFA/lower-UFA diet (P = 0.035). Marked interindividual variation in the change in serum LDL cholesterol response (-1.39 to +0.77 mmol/L) to this dietary exchange was observed, with 33.7% of this variation explained by serum LDL cholesterol before the lower-SFA/higher-UFA diet and reduction in dietary SFA intake (adjusted R2 27% and 6.7%, respectively). APOE genotype was unrelated to serum LDL cholesterol response to SFA.

CONCLUSIONS

These findings support the efficacy of United Kingdom SFA dietary guidelines for the overall lowering of serum LDL cholesterol but showed marked variation in LDL cholesterol response. Further identification of the determinants of this variation will facilitate targeting and increasing the efficacy of these guidelines. The RISSCI-1 study was registered with ClinicalTrials.Gov (No. NCT03270527).

Key co-expressed genes correlated with blood serum parameters of pigs fed with different fatty acid profile diets

This study investigated how gene expression is affected by dietary fatty acids (FA) by using pigs as a reliable model for studying human diseases that involve lipid metabolism. This includes changes in FA composition in the liver, blood serum parameters and overall metabolic pathways. RNA-Seq data from 32 pigs were analyzed using Weighted Gene Co-expression Network Analysis (WGCNA). Our aim was to identify changes in blood serum parameters and gene expression between diets containing 3% soybean oil (SOY3.0) and a standard pig production diet containing 1.5% soybean oil (SOY1.5). Significantly, both the SOY1.5 and SOY3.0 groups showed significant modules, with a higher number of co-expressed modules identified in the SOY3.0 group. Correlated modules and specific features were identified, including enriched terms and pathways such as the histone acetyltransferase complex, type I diabetes mellitus pathway, cholesterol metabolism, and metabolic pathways in SOY1.5, and pathways related to neurodegeneration and Alzheimer's disease in SOY3.0. The variation in co-expression observed for HDL in the groups analyzed suggests different regulatory patterns in response to the higher concentration of soybean oil. Key genes co-expressed with metabolic processes indicative of diseases such as Alzheimer's was also identified, as well as genes related to lipid transport and energy metabolism, including CCL5, PNISR, DEGS1. These findings are important for understanding the genetic and metabolic responses to dietary variation and contribute to the development of more precise nutritional strategies.

Exosomal Lipid Biomarkers of Oligodendrocyte Pathology to Predict Scoliosis in Children with Cerebral Palsy

Introduction

Cerebral Palsy (CP), the most common cause of disability in children, is phenotypically heterogeneous. Approximately 20% of cases develop severe scoliosis. A pathological hallmark of CP is periventricular leukomalacia (PVL), which is due to dysmyelination, suggesting the possibility of a lipidomic abnormality. Risk factors for CP include perinatal hypoxia, prematurity, multiple gestation, ischemia, infection, and maternal alcohol consumption. There is evidence for low serum levels of omega-3 (ω-3) fatty acids in CP patients, and separately in idiopathic scoliosis. Many effects of free fatty acids (FFAs) are mediated via specific G protein-coupled free fatty acid receptors (FFARs), which play essential roles as nutritional and signaling molecules. FFAs, including ω-3, and their receptors are involved in the development and metabolism of oligodendrocytes (OLs), and are critical to myelination. Thus, the cases of CP that will develop severe scoliosis might be those in which there is a deficiency of ω-3, FFARs, or other lipidomic abnormality that is detectable early in the plasma. If so, we might be able to predict scoliosis and prevent it with dietary supplementation.

Methods

Blood samples were collected from four groups of patients at the Philadelphia Shriners Children's Hospital (SCH-P): 1) patients with CP; 2) severe scoliosis (>40o); 3) CP plus scoliosis; and 4) non-impaired controls stratified by age (2-18 yrs), gender, and race/ethnicity, under an IRB-approved protocol. Serum proteins and RNA were purified, and OL-derived exosomes (OL-Es) isolated, using myelin basic protein (MBP) as a late OL marker. Protein was used for the detection of MBP and FFAR by enzyme-linked immunosorbent assays (ELISAs), and by flow cytometry. RNA was assayed by digital droplet polymerase chain reaction (ddPCR) for OL markers and FFAR expression.

Results

FFAR and MBP proteins were downregulated in each of the three patient groups compared to controls, and this difference was greatest in both patients with CP plus scoliosis.

Conclusion

Altogether, MBP and FFAR levels were reduced in OL-Es from both children with CP plus scoliosis. The lipid abnormalities specific to CP with scoliosis were concentrated in OLs. Our data might i) suggest therapeutic targets to reduce dysmyelination and scoliosis in CP, ii) predict which children are at risk for developing scoliosis, iii) lead to therapeutic trials of fatty acids for CP and other dysmyelinating neurological disorders.

Maternal Blood Lipid Biomarkers of Oligodendrocyte Pathology to Predict Fetal Alcohol Spectrum Disorders

Introduction

Up to 9.9% of children have fetal alcohol spectrum disorders (FASD), the most frequent cause of intellectual disability in the US. FASD may involve abnormal brain development, including dysmyelination, suggesting abnormal development of oligodendrocytes (OLs), which make myelin and are rich in lipids. Indeed, low serum levels of omega-3 fatty acids (ω-3) have been reported in FASD. Free fatty acids bind to specific receptors (FFARs). We have isolated cell type-specific fetal brain-derived exosomes (FB-E) from maternal blood and sampled their contents to search for lipid-related biomarkers that predict FASD.

Methods

Blood samples were collected from two groups of pregnant women: 1) those who consumed EtOH during pregnancy, and 2) non-EtOH using controls, under an IRB-approved protocol. Serum and OL-derived exosomes (OL-Es) were used to assay myelin basic protein (MBP) and FFAR by ELISA and droplet digital PCR (ddPCR), respectively.

Results

FFAR and MBP proteins were downregulated in the EtOH group compared to controls, and this difference was greatest in OL-Es from maternal blood compared maternal serum.

Conclusion

MBP and FFAR levels were reduced in OL-Es from EtOH-consuming pregnant women. The data suggest potential therapeutic targets to predict which children are at risk for developing FASD and reduce dysmyelination in developing.

A novel fatty acid metabolism-related signature identifies features of the tumor microenvironment and predicts clinical outcome in acute myeloid leukemia

Background

Acute myeloid leukemia (AML) is the most common malignancy of the hematological system, and there are currently a number of studies regarding abnormal alterations in energy metabolism, but fewer reports related to fatty acid metabolism (FAM) in AML. We therefore analyze the association of FAM and AML tumor development to explore targets for clinical prognosis prediction and identify those with potential therapeutic value.

Methods

The identification of AML patients with different fatty acid metabolism characteristics was based on a consensus clustering algorithm. The CIBERSORT algorithm was used to calculate the proportion of infiltrating immune cells. We used Cox regression analysis and least absolute shrinkage and selection operator (LASSO) regression analysis to construct a signature for predicting the prognosis of AML patients. The Genomics of Drug Sensitivity in Cancer database was used to predict the sensitivity of patient samples in high- and low-risk score groups to different chemotherapy drugs.

Results

The consensus clustering approach identified three molecular subtypes of FAM that exhibited significant differences in genomic features such as immunity, metabolism, and inflammation, as well as patient prognosis. The risk-score model we constructed accurately predicted patient outcomes, with area under the receiver operating characteristic curve values of 0.870, 0.878, and 0.950 at 1, 3, and 5 years, respectively. The validation cohort also confirmed the prognostic evaluation performance of the risk score. In addition, higher risk scores were associated with stronger fatty acid metabolisms, significantly higher expression levels of immune checkpoints, and significantly increased infiltration of immunosuppressive cells. Immune functions, such as inflammation promotion, para-inflammation, and type I/II interferon responses, were also significantly activated. These results demonstrated that immunotherapy targeting immune checkpoints and immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs) and M2 macrophages, are more suitable for patients with high-risk scores. Finally, the prediction results of chemotherapeutic drugs showed that samples in the high-risk score group had greater treatment sensitivity to four chemotherapy drugs in vitro.

Conclusions

The analysis of the molecular patterns of FAM effectively predicted patient prognosis and revealed various tumor microenvironment (TME) characteristics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01687-x.

Nutrigenomics of Dietary Lipids

Dietary lipids have a major role in nutrition, not only for their fuel value, but also as essential and bioactive nutrients. This narrative review aims to describe the current evidence on nutrigenomic effects of dietary lipids. Firstly, the different chemical and biological properties of fatty acids contained both in plant- and animal-based food are illustrated. A description of lipid bioavailability, bioaccessibility, and lipotoxicity is provided, together with an overview of the modulatory role of lipids as pro- or anti-inflammatory agents. Current findings concerning the metabolic impact of lipids on gene expression, epigenome, and gut microbiome in animal and human studies are summarized. Finally, the effect of the individual’s genetic make-up on lipid metabolism is described. The main goal is to provide an overview about the interaction between dietary lipids and the genome, by identifying and discussing recent scientific evidence, recognizing strengths and weaknesses, to address future investigations and fill the gaps in the current knowledge on metabolic impact of dietary fats on health.

Gene expression profile of peripheral blood mononuclear cells in mild to moderate obesity in dogs

Background

Molecular mechanisms and early diagnosis on the development of mild to moderate of canine obesity are not understood although recent dog obesity is a widespread problem. To understand the differences between normal weight and mild to moderate obesity, the purpose of this study is to investigate the gene expression profiles of peripheral blood mononuclear cells (PBMC) in dogs.

Methods

This study comprised a sample of 12 privately-owned Miniature Dachshund, which were divided into two groups (obese and control) based on body condition scores (BCS). Serum biochemical parameters and PBMC gene expression profiles were compared between groups.

Results

A statistically significant between group differences was recorded for body weight (BW), BCS, serum Insulin and triglyceride (TG) levels (p < 0.05). RNA-seq revealed the upregulated 154 genes and the downregulated 198 genes in obese dogs at more than 3.5-fold change compared with control animals. Hemoglobin subunits alpha- and beta-like were detected in the downregulated genes. RT-PCR analysis showed downregulation of FOLH1, ALAS2 and LOC100855540 genes, and upregulation of BCL2L15 gene, suggesting that the metabolic difference between normal and mild to moderate obesity was involved in the hemoglobin metabolism.

Conclusions

This study revealed significant differences in the gene expression of BCL2L15, FOLH1, ALAS2, and hemoglobin subunits such as LOC100855540 between normal weight and mild to moderate obese dogs, which indicate that these genes may prevent the obesity in dogs and be potentially useful for diagnosis of mild to moderate obesity.

Sex and Menopause Modify the Effect of Single Nucleotide Polymorphism Genotypes on Fibrosis in NAFLD

The development of fibrosis in nonalcoholic fatty liver disease (NAFLD) is influenced by genetics, sex, and menopausal status, but whether genetic susceptibility to fibrosis is influenced by sex and reproductive status is unclear. Our aim was to identify metabolism-related single nucleotide polymorphisms (SNPs), whose effect on NAFLD fibrosis is significantly modified by sex and menopausal status. We performed a cross-sectional, proof-of-concept study of 616 patients in the Duke NAFLD Clinical Database and Biorepository. The primary outcome was nonalcoholic steatohepatitis-Clinical Research Network (NASH-CRN) fibrosis stage. Menopause status was self-reported; age 51 years was used as a surrogate for menopause in patients with missing menopause data. The Metabochip was used to obtain 98,359 SNP genotypes in known metabolic pathway genes for each patient. We used additive genetic models to characterize sex and menopause-specific effects of SNP genotypes on NAFLD fibrosis stage. In the main effects analysis, none of the SNPs were associated with fibrosis at P < 0.05 after correcting for multiple comparisons. Twenty-five SNPs significantly interacted with sex/menopause to affect fibrosis stage (interaction P < 0.0001). After removal of loci in linkage disequilibrium, 10 independent loci were identified. Six were in the following genes: KCNIP4 (potassium voltage-gated channel interacting protein 4), PSORS1C1 (psoriasis susceptibility 1 candidate 1), KLHL8 (Kelch-like family member 8), GLRA1 (glycine receptor alpha 1), NOTCH2 (notch receptor 2), and PRKCH (protein kinase C eta), and four SNPs were intergenic. In stratified models, four SNPs were significant in premenopausal and postmenopausal women, three only in postmenopausal women, two in men and postmenopausal women, and one only in premenopausal women. Conclusion: We identified 10 loci with a significant sex/menopause interaction with respect to fibrosis. None of these SNPs were significant in all sex/menopause groups, suggesting modulation of genetic susceptibility to fibrosis by sex and menopause status. Future studies of genetic predictors of NAFLD progression should account for sex and menopause.

Effects of exercise before breakfast on plasma free fatty acid profile and 24-h fat oxidation

Background

Free fatty acids (FFAs) are an important source of energy, and also serve as signaling molecules to regulate gene expression. Exercise performed in a post-absorptive state, in contrast to that performed in a postprandial state, increases 24-h fat oxidation under an energy-balanced condition. The primary aim of the present study was to clarify whether the effects of exercise on the concentration and composition of plasma FFAs, which may underlie distinct effects of exercise on 24-h fat oxidation, depend on the nutritional state of the individual when performing the exercise.

Methods

Ten healthy young men underwent 3 trials of indirect calorimetry in a metabolic chamber. The subjects performed exercise at 60% of VO_2max for 60 min in either a post-absorptive or postprandial state, or remained sedentary without an exercise session (control). All trials were designed to be energy balanced over 24 h. Blood samples were collected immediately before and after exercise.

Results

Fat oxidation over 24 h was increased only when exercise was performed in a post-absorptive state (control, 531 ± 60; post-absorptive, 779 ± 70; postprandial, 569 ± 37 kcal/24 h). The increase in the 24-h fat oxidation was related to the magnitude of the transient carbohydrate deficit after exercise. The plasma FFA concentration after exercise was higher in the post-absorptive trial (0.38 ± 0.04) than in the control (0.13 ± 0.01) and postprandial (0.15 ± 0.02 mM) trials. The ratio of unsaturated to saturated (U/S) fatty acids after exercise was higher in the post-absorptive trial (1.76 ± 0.06) than in the control (1.56 ± 0.07) and postprandial (1.53 ± 0.08) trials. On the other hand, the plasma FFA concentration after exercise in a postprandial state did not differ significantly from that in the control trial.

Conclusion

Exercise performed in a post-absorptive state effectively increased the plasma FFA concentration and U/S ratio to a greater degree than exercise performed in a postprandial state, underlying the increase in the 24-h fat oxidation. The increase in the plasma FFA concentration was related to the transient carbohydrate deficit after exercise.

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Exercise performed in post-absorptive state increases 24-h fat oxidation.

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Exercise performed in a post-absorptive state increased the ratio of U/S ratio.

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The plasma FFA concentration was related to the transient carbohydrate deficit.

Partitioning of fatty acids into tissues and fluids from reproductive organs of ewes as affected by dietary phenolic extracts

Evaluation of dietary interventions with regard to fertility problems often observed in ruminant livestock is of global interest. Though the effects of polyphenol supplementation in ruminants on digestion and food quality are well described, the impact on reproductive tissues and fluids remains scarcely investigated. These compounds protect dietary unsaturated fatty acids (FA) from oxidation and biohydrogenation and thus saturation. In addition, modification of the expression of genes associated with FA metabolism may occur. Therefore, we characterized for the first time the FA profiles of reproductive tissues and fluids and investigated their potential modification by dietary polyphenols in 22 cyclic ewes. The animals were randomly divided into four groups and fed a basal diet of meadow hay and one of four concentrate types either non-supplemented (control) or supplemented with grape seed extract, Acacia mearnsii bark extract (13 g/kg dry matter (DM) each) or a combination of both (26 g/kg DM). After 10 weeks of feeding, the animals were slaughtered. Samples of reproductive (oviduct, uterus) and metabolically differently active tissues (liver, muscle, adipose) as well as of plasma and fluids from oviduct and uterus were analysed for their FA composition. In addition, the expression of lipid metabolic and antioxidant genes was analysed in all tissues except the adipose tissue. Fatty acid profiles in tissues and fluids as well as gene expression in tissues significantly differed between the different fluids and tissues. In contrast, only a few diet and matrix (fluid or tissue) × diet interactions were observed. Still, the FA profile of the uterus was the only one not at all affected by the diet. The mRNA expression was not affected by the diet for most of the genes investigated, which might in part be explained by the similar plasma polyphenol concentrations found at slaughter. Overall, our findings contribute to an improved understanding of the characteristic FA composition of reproductive tissues and fluids in sheep. In addition, the effect of polyphenols on different tissues, fluids and tissue gene expression has been confirmed as described in other animal species.

Serum Omega-6 Fatty Acids and Immunology-Related Gene Expression in Peripheral Blood Mononuclear Cells: A Cross-Sectional Analysis in Healthy Children

SCOPE

Some studies suggest that a high dietary intake of omega-6 fatty acids is pro-inflammatory. However, whether omega-6 fatty acids actually cause pathogenic inflammation in humans is debated. Therefore, the associations between expression of immunology-related genes in peripheral blood mononuclear cells (PBMCs) and serum total omega-6 PUFA status are investigated.

METHODS AND RESULTS

Serum fatty acid profile and expression of 460 immunology-related genes in PBMCs from 58 healthy children (6-13 years) is measured, and examined the expression differences between children with high or low total omega-6 PUFA status (upper vs lower tertile). Taken together, both univariate analyses and integrated omics analyses support that while high omega-6 PUFA level associated with higher expressing of genes related to innate immune responses, it also associated with lower expression of several genes related to adaptive immune responses.

CONCLUSION

Omega-6 PUFA status associated both positively and negatively with expression of specific immunology-related genes in PBMCs in healthy children. The results may suggest a nuanced role for omega-6 fatty acids in the interphase of lipids and inflammation, and warrants further examination in gene-environment studies and randomized controlled trials.