Fatty acids as signal transducing molecules: involvement in the differentiation of preadipose to adipose cells

Supplementation with rumen-inert fat in the growing phase altered adipogenic gene expression and the size and number of adipocytes in Hanwoo steers

We hypothesized that the provision of rumen-inert fat (RIF) to growing cattle (9 to 13 mo of age) would affect the expression of genes involved in lipid metabolism and thereby affect the size and number of adipocytes of steers slaughtered at 30 mo of age. Thirty steers with an average initial body weight (BW) of 239 ± 25 kg were allocated to six pens, balanced for BW and genetic merit for marbling, and assigned to one of two treatment groups: control (only basal diet) or test diet (basal diet with 200 g of RIF per day, on an as-fed basis) for 5 mo. Biopsy samples of longissimus lumborum (LM) muscle were then collected for analysis of fatty acid composition and gene expression. Both groups were then fed the same basal diets during the early and late fattening phases, without RIF, until slaughter (average shrunk BW = 759 kg). Supplementation with RIF increased the longissimus thoracis (LT) intramuscular fatty acid concentration at slaughter (P = 0.087) and numerically increased the quality grade score (P = 0.106). The LM intramuscular relative mRNA expression of genes such as PPARα, ZFP423 and SREBP1, FASN, SCD, FABP4, GPAT1, and DGAT2 were downregulated (P < 0.1) following RIF supplementation. Supplementation of RIF decreased (P < 0.1) diameter and concomitantly increased intramuscular adipocytes per viewing section at slaughter. This likely was caused by promotion of triacylglycerol hydrolysis during the growing phase. Another possible explanation is that the relative mRNA expression of gene ATGL was upregulated by RIF supplementation during the growing (P < 0.1) and the fattening phases (P < 0.05), while the genes associated with fatty acid uptake (FABP4) and esterification (DGAT2) were downregulated during the growing phase and upregulated (P < 0.1) during the fattening phase. This implies that the lipid turnover rate was higher for steers during the growing than fattening phase. This study demonstrated that RIF supplementation during the growing phase induced a carryover effect on the lipogenic transcriptional regulation involved in adipocyte lipid content of intramuscular adipose tissue; increased triacylglycerol hydrolysis during the growing phase subsequently was followed by increased lipid accumulation during the fattening phases.

Bioactive dietary components-Anti-obesity effects related to energy metabolism and inflammation

Obesity is the result of the long-term energy imbalance between the excess calories consumed and the few calories expended. Reducing the intake of energy dense foods (fats, sugars), and strategies such as fasting and caloric restriction can promote body weight loss. Not only energy in terms of calories, but also the specific composition of the diet can affect the way the food is absorbed and how its energy is stored, used or dissipated. Recent research has shown that bioactive components of food, such as polyphenols and vitamins, can influence obesity and its pathologic complications such as insulin resistance, inflammation and metabolic syndrome. Individual micronutrients can influence lipid turnover but for long-term effects on weight stability, dietary patterns containing several micronutrients may be required. At the molecular level, these molecules modulate signaling and the expression of genes that are involved in the regulation of energy intake, lipid metabolism, adipogenesis into white, beige and brown adipose tissue, thermogenesis, lipotoxicity, adipo/cytokine synthesis, and inflammation. Higher concentrations of these molecules can be reached in the intestine, where they can modulate the composition and action of the microbiome. In this review, the molecular mechanisms by which bioactive compounds and vitamins modulate energy metabolism, inflammation and obesity are discussed.

Dietary Omega-6/Omega-3 Polyunsaturated Fatty Acid (PUFA) and Omega-3 Are Associated With General and Abdominal Obesity in Adults: UK National Diet and Nutritional Survey

Introduction

The link between dietary fats and obesity is still controversial, as in Western diets the percentage of energy from total fat has decreased while the intake of omega-6 has increased, and omega-3 decreased. These changes have corresponded with a significant increase in the prevalence of obesity.

Objective

This study aims to examine the association of percentages of energy intake (EI) from omega-3 and omega-6 and Σω-6/Σω-3 ratio with BMI and two proxy indicators of central obesity (waist circumference [WC], waist-to-height ratio [WHtR]) and relative fat mass (RFM) estimator of whole-body fat.

Design

A representative sample of 3,733 adults was used from the UK National Diet and Nutrition Survey Rolling Programme (2008/09-2018/19). An estimated four-day food record was used to calculate dietary intake. Regression models were used to verify the association of omega-3 and omega-6 and quintiles of Σω-6/ Σω-3 ratio with general and abdominal obesity with adjustment for important confounders. A p-value of <0.05 represented statistical significance.

Results

The findings of this study show that the average ratio of Σω-6/Σω-3 was 5.5:1 ± 2. There was a significant association between the ratio of Σω-6/Σω-3 and BMI, WC, WHtR and RFM. However, the percentage of total EI from total fat was only significant with BMI, while the percentage of EI from omega-3 was negatively associated with WC, WHtR and RFM. No association was found between the percentage of EI from omega-6 and general or abdominal obesity.

Conclusion

The effect of Σω-6/Σω-3 may be largely driven by a deficiency in the intake of omega-3. Omega-6 and omega-3 should be listed as such in national surveys instead of polyunsaturated fatty acid (PUFA). Meeting recommended levels of omega-3 and lowering Σω-6/Σω-3 are imperative to establish healthier dietary patterns and prevent obesity.

Omega-3 Polyunsaturated Fatty Acids Protect against High-Fat Diet-Induced Morphological and Functional Impairments of Brown Fat in Transgenic Fat-1 Mice

The role of omega-3 polyunsaturated fatty acids (n-3 PUFAs) in the regulation of energy homeostasis remains poorly understood. In this study, we used a transgenic fat-1 mouse model, which can produce n-3 PUFAs endogenously, to investigate how n-3 PUFAs regulate the morphology and function of brown adipose tissue (BAT). We found that high-fat diet (HFD) induced a remarkable morphological change in BAT, characterized by “whitening” due to large lipid droplet accumulation within BAT cells, associated with obesity in wild-type (WT) mice, whereas the changes in body fat mass and BAT morphology were significantly alleviated in fat-1 mice. The expression of thermogenic markers and lypolytic enzymes was significantly higher in fat-1 mice than that in WT mice fed with HFD. In addition, fat-1 mice had significantly lower levels of inflammatory markers in BAT and lipopolysaccharide (LPS) in plasma compared with WT mice. Furthermore, fat-1 mice were resistant to LPS-induced suppression of UCP1 and PGC-1 expression and lipid deposits in BAT. Our data has demonstrated that high-fat diet-induced obesity is associated with impairments of BAT morphology (whitening) and function, which can be ameliorated by elevated tissue status of n-3 PUFAs, possibly through suppressing the effects of LPS on inflammation and thermogenesis.

Inhibition of palmitic acid induced adipogenesis by natural polyphenols in 3T3-L1 adipocytes

Dietary free fatty acids induce preadipocyte differentiation in the presence of a hormonal cocktail in 3T3-L1 adipocytes. Plant polyphenols are curb adipocyte differentiation and protect from metabolic stress. In the present study, we examined the effects of the saturated fatty acid, palmitic acid (PA) in presence of flavonoids, chrysin (CR) and hesperidin (HD) and phenolic acid, syringic acid (SYA) and sinapic acid (SIA). Adipocytes were incubated for 10 d with 100 μmol of PA along with 10-100 µmol CR/HD and 100-1000 µmol SYA/SIA. PA induced clonal expansion of preadipocytes, differentiation and oxidative stress in 3T3-L1 cells following 10 d of differentiation. Adipocytes treated with PA exhibited an increase of 300% in clonal population, 110% lipid and 172% reactive oxygen species accumulation. But treatment with CR, HD, SYA and SIA in the presence of PA concentration-dependent effect was observed. Concentrations of CR/HD and SYA/SIA inhibited PA-induced mRNA expression of PPARγ, C/EBPα, SREBP-1c, FAS and NOX4. Moreover, CR, HD, SYA and SIA did not exhibit toxicity in Drosophila DNA. In summary, these results suggest that dietary fatty acids act directly on adipocytes and addition of CR, HD, SYA and SIA resulted in reduction of PA-induced negative effects on 3T3-L1 adipocytes. HIGHLIGHTS: • Palmitic acid, the common dietary free fatty acid, is known to induce adipogenesis in 3T3-L1 adipocytes. • Treatment of differentiating adipocytes with flavonoids and phenolic acids reduced palmitic acid-induced clonal expansion of preadipocytes. • Phytocompounds reduced lipid accumulation and triglyceride production as well as ROS accumulation. • Thus, the phytocompounds showed effective anti-adipogenic activity even in palmitic acid challenged environment in adipocytes.

Omega-3 fats in pregnancy: could a targeted approach lead to better metabolic health for children?

The prevalence of childhood obesity is increasing worldwide, and the children of women who are obese during pregnancy are at greatest risk. This risk may be mediated by exaggeration of the normal insulin resistance of pregnancy. Omega-3 (n-3) fats are insulin sensitizing. Supplementation during pregnancy may reduce metabolic risk and adiposity in the children. Though results from animal studies are encouraging, completed clinical trials have not demonstrated this benefit. However, to our knowledge, previous studies have not targeted women who are overweight or obese while pregnant-the group at greatest risk for insulin resistance and most likely to benefit from n-3. In this narrative review, the importance of performing clinical trials restricted to women who are overweight or obese is discussed, as is the potential importance of n-3 dose, oil source and quality, and the timing of the intervention.

Decreased caveolae in AGPAT2 lacking adipocytes is independent of changes in cholesterol or sphingolipid levels: A whole cell and plasma membrane lipidomic analysis of adipogenesis

BACKGROUND

Adipocytes from lipodystrophic Agpat2^-/- mice have impaired adipogenesis and fewer caveolae. Herein, we examined whether these defects are associated with changes in lipid composition or abnormal levels of caveolae-associated proteins. Lipidome changes were quantified in differentiated Agpat2^-/- adipocytes to identify lipids with potential adipogenic roles.

METHODS

Agpat2^-/- and wild type brown preadipocytes were differentiated in vitro. Plasma membrane was purified by ultracentrifugation. Number of caveolae and caveolae-associated proteins, as well as sterol, sphingolipid, and phospholipid lipidome were determined across differentiation.

RESULTS

Differentiated Agpat2^-/- adipocytes had decreased caveolae number but conserved insulin signaling. Caveolin-1 and cavin-1 levels were equivalent between Agpat2^-/- and wild type adipocytes. No differences in PM cholesterol and sphingolipids abundance were detected between genotypes. Levels of phosphatidylserine at day 10 of differentiation were increased in Agpat2^-/- adipocytes. Wild type adipocytes had increased whole cell triglyceride, diacylglycerol, phosphatidylglycerol, phosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine, and trihexosyl ceramide, and decreased 24,25-dihydrolanosterol and sitosterol, as a result of adipogenic differentiation. By contrast, adipogenesis did not modify whole cell neutral lipids but increased lysophosphatidylcholine, sphingomyelin, and trihexosyl ceramide levels in Agpat2^-/- adipocytes. Unexpectedly, adipogenesis decreased PM levels of main phospholipids in both genotypes.

CONCLUSION

In Agpat2^-/- adipocytes, decreased caveolae is not associated with changes in PM cholesterol nor sphingolipid levels; however, increased PM phosphatidylserine content may be implicated. Abnormal lipid composition is associated with the adipogenic abnormalities of Agpat2 -/- adipocytes but does not prevent insulin signaling.

ATGL activity regulates GLUT1-mediated glucose uptake and lactate production via TXNIP stability in adipocytes

Traditionally, lipolysis has been regarded as an enzymatic activity that liberates fatty acids as metabolic fuel. However, recent work has shown that novel substrates, including a variety of lipid compounds such as fatty acids and their derivatives, release lipolysis products that act as signaling molecules and transcriptional modulators. While these studies have expanded the role of lipolysis, the mechanisms underpinning lipolysis signaling are not fully defined. Here, we uncover a new mechanism regulating glucose uptake, whereby activation of lipolysis, in response to elevated cAMP, leads to the stimulation of thioredoxin-interacting protein (TXNIP) degradation. This, in turn, selectively induces glucose transporter 1 surface localization and glucose uptake in 3T3-L1 adipocytes and increases lactate production. Interestingly, cAMP-induced glucose uptake via degradation of TXNIP is largely dependent upon adipose triglyceride lipase (ATGL) and not hormone-sensitive lipase or monoacylglycerol lipase. Pharmacological inhibition or knockdown of ATGL alone prevents cAMP-dependent TXNIP degradation and thus significantly decreases glucose uptake and lactate secretion. Conversely, overexpression of ATGL amplifies the cAMP response, yielding increased glucose uptake and lactate production. Similarly, knockdown of TXNIP elicits enhanced basal glucose uptake and lactate secretion, and increased cAMP further amplifies this phenotype. Overexpression of TXNIP reduces basal and cAMP-stimulated glucose uptake and lactate secretion. As a proof of concept, we replicated these findings in human primary adipocytes and observed TXNIP degradation and increased glucose uptake and lactate secretion upon elevated cAMP signaling. Taken together, our results suggest a crosstalk between ATGL-mediated lipolysis and glucose uptake.

Double-blind RCT of fish oil supplementation in pregnancy and lactation to improve the metabolic health in children of mothers with overweight or obesity during pregnancy: study protocol

INTRODUCTION

Maternal obesity during pregnancy is associated with adverse changes in body composition and metabolism in the offspring. We hypothesise that supplementation during pregnancy of overweight and obese women may help prevent the development of greater adiposity and metabolic dysfunction in children. Previous clinical trials investigating fish oil supplementation in pregnancy on metabolic outcomes and body composition of the children have not focused on the pregnancies of overweight or obese women.

METHODS AND ANALYSIS

A double-blind randomised controlled trial of fish oil (providing 3 g/day of n-3 polyunsaturated fatty acids) versus an equal volume of olive oil (control) taken daily from recruitment until birth, and in breastfeeding mothers, further continued for 3 months post partum. Eligible women will have a singleton pregnancy at 12-20 weeks' gestation and be aged 18-40 years with body mass index ≥25 kg/m² at baseline. We aim to recruit a minimum of 128 participants to be randomised 1:1. Clinical assessments will be performed at baseline and 30 weeks of pregnancy, including anthropometric measurements, fasting metabolic markers, measures of anxiety, physical activity, quality of life and dietary intake. Subsequent assessments will be performed when the infant is 2 weeks, 3 months and 12 months of age for anthropometry, body composition (dual-energy X-ray absorptiometry (DXA)) and blood sampling. The primary outcome of the study is a between-group difference in infant percentage body fatness, assessed by DXA, at 2 weeks of age. Secondary outcomes will include differences in anthropometric measures at each time point, percentage body fat at 3 and 12 months and homeostatic model assessment of insulin resistance at 3 months. Statistical analysis will be carried out on the principle of intention to treat.

ETHICS AND DISSEMINATION

This trial was approved by the Northern A Health and Disabilities Ethics Committee, New Zealand Ministry of Health (17/NTA/154). Results will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ACTRN12617001078347p; Pre-results.

A review on differential effects of dietary fatty acids on weight, appetite and energy expenditure

The association between weight and chronic diseases is well defined. The quality and quantity of dietary fatty acids is an important external factor and appetite and energy expenditure, are important internal factors in determining body weight. On the other hand, dietary fatty acids composition can modulate appetite and energy metabolism, but not all fats are equal in producing metabolic responses.Given the accumulating evidence for differential effects of various dietary fatty acids, one important area of investigation is to scrutinize their roles in weight, appetite and energy expenditure modulation. There is substantial evidence to suggest that saturated fatty acids have a greater effect on appetite control, although in the long run may result in more weight gain than unsaturated fatty acids due to a weaker stimulation of energy expenditure. In contrast, mono-unsaturated fats do not have much effects on appetite control, but they can be beneficial in weight control over the long term due to stimulatory effects on energy expenditure. Interestingly, in case of poly unsaturated fats, including n-3 and n-6, their effect on increasing energy expenditure is aligned, but they act differently in controlling weight and appetite.

Murine in vitro cellular models to better understand adipogenesis and its potential applications

Adipogenesis has been extensively studied using in vitro models of cellular differentiation, enabling long-term regulation of fat cell metabolism in human adipose tissue (AT) material. Many studies promote the idea that manipulation of this process could potentially reduce the prevalence of obesity and its related diseases. It has now become essential to understand the molecular basis of fat cell development to tackle this pandemic disease, by identifying therapeutic targets and new biomarkers. This review explores murine cell models and their applications for study of the adipogenic differentiation process in vitro. We focus on the benefits and limitations of different cell line models to aid in interpreting data and selecting a good cell line model for successful understanding of adipose biology.

The impact of maternal obesity and breast milk inflammation on developmental programming of infant growth

Background:

Little is known about how maternal obesity impacts breast milk (BM) composition and how BM composition may impact growth. We sought to determine the role of maternal body mass index (BMI) on BM inflammatory and oxidative stress markers and to delineate the role of these BM markers on infant growth.

Methods:

This was a secondary analysis of 40 mother-infant dyads. We first assessed the association between maternal BMI and BM marker (omega-6:omega-3 polyunsaturated fatty acid ratio (n-6:n-3 PUFA), leptin, interleukin (IL)-8, IL-6, IL-1β and malondialdehyde (MDA)) concentration at one (V1) and four (V4) months postpartum. We then examined the association between BM markers on infant growth trajectory from birth to seven months.

Results:

Higher maternal BMI was associated with higher BM n-6:n-3 PUFA (V1 β=0.12, 95% CI 0.01, 0.2; V4 β=0.13, 95% CI 0.01, 0.3) and leptin (V1 β=107, 95% CI 29, 184; V4 β=254, 95% CI 105, 403) concentrations. Infants exposed to high BM n-6:n-3 PUFA had higher BMI z-scores over time (p=0.01). Higher BM leptin was associated with lower infant percent fat mass at V4 (β=−9, 95% CI −17, −0.6). Infants exposed to high BM IL-8, IL-6, or IL-1β had higher weight z-scores over time (IL-8 p<0.001; IL-6 p<0.001; IL-1β p=0.02). There was no association between BM MDA and maternal BMI or infant growth.

Conclusions:

Higher maternal BMI is associated with higher BM n-6:n-3 PUFA and leptin concentrations. In addition, higher BM n-6:n-3 PUFA and inflammatory cytokines were associated with accelerated weight gain in infancy.

Circulating and Adipose Tissue Fatty Acid Composition in Black South African Women with Obesity: A Cross-Sectional Study

Background and Aims: During positive energy balance, excess lipid storage in subcutaneous adipose tissue (SAT) is associated with increased lipolysis. Elevated circulating fatty acid (FA) concentrations from both SAT lipolysis and dietary fat intake may result in visceral adipose tissue (VAT) accumulation, impairment of glucose metabolism, altogether increasing obesity-associated metabolic risks. We aimed to test the hypothesis that FA composition of red blood cell total phospholipids (RBC-TPL) and SAT is associated with body fat centralisation (VAT/SAT ratio) and insulin sensitivity (S_I) in black South African women with obesity. Methods: Participants’ (n = 41) body fat composition and distribution, S_I, and RBC-TPL, abdominal and gluteal SAT (gSAT) FA composition (gas-liquid chromatography) were measured. Results: RBC-TPL contained higher proportions of saturated fatty acids (SFAs) than SAT (p < 0.001), which were associated with lower S_I (p < 0.05). Mono-unsaturated fatty acids (MUFAs) and stearoyl-CoA desaturase-1 (SCD1)-16 were lower, while poly-unsaturated fatty acids (PUFAs), and delta-5 and delta-6 desaturase indices were higher in RBC-TPL than SAT (p < 0.001). Interestingly, FA profiles differed between SAT depots with higher SFAs and lower MUFAs, SCD1-16 and SCD1-18 indices in abdominal compared to gluteal SAT (p < 0.01). In both SAT depots, higher SFAs and lower PUFAs (n-3 and n-6) correlated with lower VAT/SAT ratio; and lower PUFAs (n-3 and n-6) and higher total MUFA correlated with higher S_I. Conclusion: Our findings confirm the relationships between the FA composition of RBC-TPL and SAT and metabolic risk in black women with obesity, which are dependent on both the FA class, and the tissue type/blood compartment in which they are distributed.

Reclassifying Hepatic Cell Death during Liver Damage: Ferroptosis-A Novel Form of Non-Apoptotic Cell Death?

Ferroptosis has emerged as a new type of cell death in different pathological conditions, including neurological and kidney diseases and, especially, in different types of cancer. The hallmark of this regulated cell death is the presence of iron-driven lipid peroxidation; the activation of key genes related to this process such as glutathione peroxidase-4 (gpx4), acyl-CoA synthetase long-chain family member-4 (acsl4), carbonyl reductase [NADPH] 3 (cbr3), and prostaglandin peroxidase synthase-2 (ptgs2); and morphological changes including shrunken and electron-dense mitochondria. Iron overload in the liver has long been recognized as both a major trigger of liver damage in different diseases, and it is also associated with liver fibrosis. New evidence suggests that ferroptosis might be a novel type of non-apoptotic cell death in several liver diseases including non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALD), drug-induced liver injury (DILI), viral hepatitis, and hemochromatosis. The interaction between iron-related lipid peroxidation, cellular stress signals, and antioxidant systems plays a pivotal role in the development of this novel type of cell death. In addition, integrated responses from lipidic mediators together with free iron from iron-containing enzymes are essential to understanding this process. The presence of ferroptosis and the exact mechanisms leading to this non-apoptotic type of cell death in the liver remain scarcely elucidated. Recognizing ferroptosis as a novel type of cell death in the liver could lead to the understanding of the complex interaction between different types of cell death, their role in progression of liver fibrosis, the development of new biomarkers, as well as the use of modulators of ferroptosis, allowing improved theranostic approaches in the clinic.

Multifaceted Oncogenic Role of Adipocytes in the Tumour Microenvironment

Obesity has for decades been recognised as one of the major health concerns. Recently accumulated evidence has established that obesity or being overweight is strongly linked to an increased risk of cancer. However, it is still not completely clear how adipose tissue (fat), along with other stromal connective tissues and cells, contribute to tumour initiation and progression. In the tumour microenvironment, the adipose tissue cells, in particular the adipocytes, secrete a number of adipokines, including growth factors, hormones, collagens, fatty acids, and other metabolites as well as extracellular vesicles to shape and condition the tumour and its microenvironment. In fact, the adipocytes, through releasing these factors and materials, can directly and indirectly facilitate cancer cell proliferation, apoptosis, metabolism, angiogenesis, metastasis and even chemotherapy resistance. In this chapter, the multidimensional role played by adipocytes, a major and functional component of the adipose tissue, in promoting cancer development and progression within the tumour microenvironment will be discussed.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.

The effect of maternal DHA supplementation on body fat mass in children at 7 years: follow-up of the DOMInO randomized controlled trial

BACKGROUND

Animal studies have suggested that an increased supply of omega-3 long chain polyunsaturated fatty acids (LCPUFA), in particular docosahexaenoic acid (DHA), during the perinatal period can prevent later excess body fat mass. However, previous human studies have produced inconsistent findings, and few have assessed potential effects beyond 6 years of age.

OBJECTIVE

To evaluate the effect of supplementing women in the second half of pregnancy with omega-3 LCPUFA, chiefly as DHA, on the percentage body fat of children at 7 years of age, as assessed by two methods: air displacement plethysmography (BOD POD) and bioelectrical impedance spectroscopy (BIS).

DESIGN

A time-restricted follow up at 7 years of age of children born to mothers enrolled in DOMInO (DHA to Optimise Maternal Infant Outcome) randomized controlled trial, in which women took either high-DHA tuna oil (800mg/day DHA) or placebo capsules from 20 weeks' gestation to delivery, at Adelaide-based centers. Primary outcomes were the percentage body fat at 7 years of age as assessed by both BOD POD and BIS. Weight, height, waist/hip circumferences and BMI were also recorded.

RESULTS

A total of 252 DOMInO children (n=135 males, n=117 females) completed the follow up study. There were no differences between the DHA and placebo groups in percentage body fat as assessed by either BOD POD [adjusted mean difference: -0.35, 95% CI: -1.46, 2.16; P=0.71] or BIS [adjusted mean difference: 0.64, 95% CI: -0.99, 2.27; P=0.44]. BMI z-scores were also similar between groups [adjusted mean difference: 0.18, 95% CI: -0.10, 0.45; P=0.21]. There were also no differences in height, weight or waist and hip circumference between the DHA and placebo groups at 7 years of age.

CONCLUSION

DHA supplementation in the second half of pregnancy has no effect on childhood growth or fat mass at 7 years of age, supporting findings from follow ups of the DOMInO children at 3 and 5 years.

Long-chain omega-3 polyunsaturated fatty acids decrease mammary tumor growth, multiorgan metastasis and enhance survival

Epidemiological studies show a reduced risk of breast cancer (BC) in women consuming high levels of long-chain (LC) omega-3 (ω-3) fatty acids (FAs) compared with women who consumed low levels. However, the regulatory and mechanistic roles of dietary ω-6 and LC-ω-3 FAs on tumor progression, metastasis and survival are poorly understood. Female BALB/c mice (10-week old) were pair-fed with a diet containing ω-3 or an isocaloric, isolipidic ω-6 diet for 16 weeks prior to the orthotopic implantation of 4T1 mammary tumor cells. Major outcomes studied included: mammary tumor growth, survival analysis, and metastases analyses in multiple organs including pulmonary, hepatic, bone, cardiac, renal, ovarian, and contralateral MG (CMG). The dietary regulation of the tumor microenvironment was evaluated in mice autopsied on day-35 post tumor injection. In mice fed the ω-3 containing diet, there was a significant delay in tumor initiation and prolonged survival relative to the ω-6 diet-fed group. The tumor size on day 35 post tumor injection in the ω-3 group was 50% smaller and the frequencies of pulmonary and bone metastases were significantly lower relative to the ω-6 group. Similarly, the incidence/frequencies and/or size of cardiac, renal, ovarian metastases were significantly lower in mice fed the ω-3 diet. The analyses of the tumor microenvironment showed that tumors in the ω-3 group had significantly lower numbers of proliferating tumor cells (Ki67⁺)/high power field (HPF), and higher numbers of apoptotic tumor cells (TUNEL⁺)/HPF, lower neo-vascularization (CD31⁺ vessels/HPF), infiltration by neutrophil elastase⁺ cells, and macrophages (F4/80⁺) relative to the tumors from the ω-6 group. Further, in tumors from the ω-3 diet-fed mice, T-cell infiltration was 102% higher resulting in a neutrophil to T-lymphocyte ratio (NLR) that was 76% lower (p < 0.05). Direct correlations were observed between NLR with tumor size and T-cell infiltration with the number of apoptotic tumor cells. qRT-PCR analysis revealed that tumor IL10 mRNA levels were significantly higher (six-fold) in the tumors from mice fed the ω-3 diet and inversely correlated with the tumor size. Our data suggest that dietary LC-ω-3FAs modulates the mammary tumor microenvironment slowing tumor growth, and reducing metastases to both common and less preferential organs resulting in prolonged survival. The surrogate analyses undertaken support a mechanism of action by dietary LC-ω-3FAs that includes, but is not limited to decreased infiltration by myeloid cells (neutrophils and macrophages), an increase in CD3⁺ lymphocyte infiltration and IL10 associated anti-inflammatory activity.

Triglyceride profiling in adipose tissues from obese insulin sensitive, insulin resistant and type 2 diabetes mellitus individuals

Background

Lipid intermediates produced during triacylglycerols (TAGs) synthesis and lipolysis in adipocytes interfere with the intracellular insulin signaling pathway and development of insulin resistance. This study aims to compare TAG species and their fatty acid composition in adipose tissues from insulin sensitive (IS), insulin resistant (IR) and type 2 diabetes mellitus (T2DM) obese individuals.

Methods

Human subcutaneous and omental adipose tissue biopsies were obtained from 64 clinically characterized obese individuals during weight reduction surgery. TAGs were extracted from the adipose tissues using the Bligh and Dyer method, then were subjected to non-aqueous reverse phase ultra-high performance liquid chromatography and full scan mass spectrometry acquisition and data dependent MS/MS on LTQ dual cell linear ion trap. TAGs and their fatty acid contents were identified and compared between IS, IR and T2DM individuals and their levels were correlated with metabolic traits of participants and the adipogenic potential of preadipocyte cultures established from their adipose tissues.

Results

Data revealed 76 unique TAG species in adipose tissues identified based on their exact mass. Analysis of TAG levels revealed a number of TAGs that were significantly altered with disease progression including C46:4, C48:5, C48:4, C38:1, C50:3, C40:2, C56:3, C56:4, C56:7 and C58:7. Enrichment analysis revealed C12:0 fatty acid to be associated with TAGs least abundant in T2DM whereas C18:3 was found in both depleted and enriched TAGs in T2DM. Significant correlations of various adipose tissue-derived TAG species and metabolic traits were observed, including age and body mass index, systemic total cholesterol, TAGs, and interleukin-6 in addition to adipogenic potential of preadipocytes derived from the same adipose tissues.

Conclusion

Pilot data suggest that adipose tissues from obese IR and T2DM individuals exhibit TAG-specific signatures that may contribute to their increased risk compared to their IS counterparts. Future experiments are warranted to investigate the functional relevance of these specific lipidomic profiles.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1548-x) contains supplementary material, which is available to authorized users.

Dietary omega-3 and omega-6 polyunsaturated fatty acids modulate hepatic pathology

Recent evidence has suggested that dietary polyunsaturated fatty acids (PUFAs) modulate inflammation; however, few studies have focused on the pathobiology of PUFA using isocaloric and isolipidic diets and it is unclear if the associated pathologies are due to dietary PUFA composition, lipid metabolism or obesity, as most studies compare diets fed ad libitum. Our studies used isocaloric and isolipidic liquid diets (35% of calories from fat), with differing compositions of omega (ω)-6 or long chain (Lc) ω-3 PUFA that were pair-fed and assessed hepatic pathology, inflammation and lipid metabolism. Consistent with an isocaloric, pair-fed model we observed no significant difference in diet consumption between the groups. In contrast, the body and liver weight, total lipid level and abdominal fat deposits were significantly higher in mice fed an ω-6 diet. An analysis of the fatty acid profile in plasma and liver showed that mice on the ω-6 diet had significantly more arachidonic acid (AA) in the plasma and liver, whereas, in these mice ω-3 fatty acids such as eicosapentaenoic acid (EPA) were not detected and docosahexaenoic acid (DHA) was significantly lower. Histopathologic analyses documented that mice on the ω-6 diet had a significant increase in macrovesicular steatosis, extramedullary myelopoiesis (EMM), apoptotic hepatocytes and decreased glycogen storage in lobular hepatocytes, and hepatocyte proliferation relative to mice fed the Lc ω-3 diet. Together, these results support PUFA dietary regulation of hepatic pathology and inflammation with implications for enteral feeding regulation of steatosis and other hepatic lesions.

Effects of maternal omega-3 fatty acids supplementation during pregnancy/lactation on body composition of the offspring: A systematic review and meta-analysis

BACKGROUND & AIMS

The effect of maternal omega-3 fatty acids intake on the body composition of the offspring is unclear. The aim of this study was to conduct a systematic review and meta-analysis to confirm the effects of omega-3 fatty acids supplementation during pregnancy and/or lactation on body weight, body length, body mass index (BMI), waist circumference, fat mass and sum of skinfold thicknesses of offspring.

METHODS

Human intervention studies were selected by a systematic search of PubMed, Web of Science, the Cochrane Library and references of related reviews and studies. Randomized controlled trials of maternal omega-3 fatty acids intake during pregnancy or lactation for offspring's growth were included. The data were analyzed with RevMan 5.3 and Stata 12.0. Effect sizes were presented as weighted mean differences (WMD) or standardized mean difference (SMD) with 95% confidence intervals (95% CI).

RESULTS

Twenty-six studies comprising 10,970 participants were included. Significant increases were found in birth weight (WMD = 42.55 g, 95% CI: 21.25, 63.85) and waist circumference (WMD = 0.35 cm, 95% CI: 0.04, 0.67) in the omega-3 fatty acids group. There were no effects on birth length (WMD = 0.09 cm, 95% CI: -0.03, 0.21), postnatal length (WMD = 0.13 cm, 95% CI: -0.11, 0.36), postnatal weight (WMD = 0.04 kg, 95% CI: -0.07, 0.14), BMI (WMD = 0.09, 95% CI: -0.05, 0.23), the sum of skinfold thicknesses (WMD = 0.45 mm, 95% CI: -0.30, 1.20), fat mass (WMD = 0.05 kg, 95% CI: -0.01, 0.11) and the percentage of body fat (WMD = 0.04%, 95% CI: -0.38, 0.46).

CONCLUSIONS

This meta-analysis showed that maternal omega-3 fatty acids supplementation can increase offspring's birth weight and postnatal waist circumference. However, it did not appear to influence children's birth length, postnatal weight/length, BMI, sum of skinfold thicknesses, fat mass and the percentage of body fat during postnatal period. Larger, well-designed studies are recommended to confirm this conclusion.

Effect of eicosapentaenoic acid on bovine cumulus-oocyte complex in vitro

The aim of the present study was to investigate the effects of eicosapentaenoic acid (EPA) supplementation during in vitro maturation (IVM) of bovine oocytes. The concentrations tested in all experiments were 1 nM, 1 μM, and 1 mM EPA. The effect of EPA was evaluated on cumulus-oocyte complexes (COC) by oocyte maturation (cumulus expansion area and oocyte nuclear maturation), genotoxicity [single cell gel electrophoresis (SCGE)], and cytotoxicity (apoptosis, viability, and MTT assays) end points. The maturation parameters were affected by exposure of COC to different EPA concentrations in the IVM medium. Cumulus expansion area increased in the presence of 1 nM EPA (P < 0.05) whereas addition of 1 nM EPA (P < 0.05) decreased cumulus expansion after 24 h of IVM. Moreover, the maturation rate significantly decreased when 1 mM of EPA was assayed (P < 0.001). EPA at 1 nM induced genotoxic and cytotoxic effects on bovine cumulus cells (CC) and primary DNA lesions (P < 0.001). A significant increase in the frequency of apoptotic (P < 0.01) and necrotic (P < 0.001) cells was observed after 24 h of treatment with 1 nM, 1 μM, and 1 mM EPA. Mitochondrial activity was altered with 1 mM EPA (P < 0.001). We inferred that optimal oocyte quality was partially dependent on the presence of adequate EPA concentrations; EPA could be beneficial to improve oocyte quality in the maturation process, because low concentration tested (1 nM EPA) improved cumulus expansion.

Maternal and fetal lipid metabolism under normal and gestational diabetic conditions

Maternal lipids are strong determinants of fetal fat mass. Here we review the overall lipid metabolism in normal and gestational diabetes mellitus (GDM) pregnancies. During early pregnancy, the increase in maternal fat depots is facilitated by insulin, followed by increased adipose tissue breakdown and subsequent hypertriglyceridemia, mainly as a result of insulin resistance (IR) and estrogen effects. The response to diabetes is variable as a result of greater IR but decreased estrogen levels. The vast majority of fatty acids (FAs) in the maternal circulation are esterified and associated with lipoproteins. These are taken up by the placenta and hydrolyzed by lipases. The released FAs enter various metabolic routes and are released into fetal circulation. Although these determinants are modified in maternal GDM, the fetus does not seem to receive more FAs than in non-GDM pregnancies. Long-chain polyunsaturated FAs are essential for fetal development and are obtained from the mother. Mitochondrial FA oxidation occurs in fetal tissue and in placenta and contributes to energy production. Fetal fat accretion during the last weeks of gestation occurs very rapidly and is sustained not only by FAs crossing the placenta, but also by fetal lipogenesis. Fetal hyperinsulinemia in GDM mothers promotes excess accretion of adipose tissue, which gives rise to altered adipocytokine profiles. Fetal lipoproteins are low at birth, but the GDM effects are unclear. The increase in body fat in neonates of GDM women is a risk factor for obesity in early childhood and later life.

Sex-related differences in the associations between plasma free fatty acid levels and clinical features in patients with hypertrophic cardiomyopathy

Background

Previous studies have indicated that inefficient energy utilization may play a pivotal role in hypertrophic cardiomyopathy (HCM). However, whether plasma free fatty acid (FFA), a main energy substrate of heart, has an effect on HCM remains unclear. Besides, several studies have suggested sex-related differences in HCM features and FFA metabolism. Here, we aimed to explore the association between plasma FFA levels and HCM and potential effects of sex on this relation.

Methods

A total of 412 patients (age 47.8 ± 12.7 years, 243 males (59.0%)) with HCM were recruited. Complete medical history was collected. Echocardiography and cardiovascular magnetic resonance imaging (CMRI) were performed. Fasting plasma FFA was determined by clinical laboratory. Left ventricular mass (LVM), maximum wall thickness (MWT), and left atrium diameter (LAD) were assessed with CMRI.

Results

The median FFA levels were 0.38 (interquartile range (IQR) 0.27–0.52) mmol/L in men and 0.40 (IQR 0.30–0.59) mmol/L in women. The FFA levels were significantly lower in men compared with those in women (p = 0.005). Compared with women, men had greater LVM index (LVMI) (96.8 ± 37.6 vs. 78.6 ± 31.5 g/m², p < 0.001). FFA levels in male patients correlated positively with LVM, LVMI, LAD, cholesterol levels, high-density lipoprotein-cholesterol (HDL-C) levels, heart rate, and systolic blood pressure (SBP). However, none of these variables were significantly associated with sqrt (FFA) in female patients except a borderline correlation of LAD (p = 0.050). Multiple linear regression analysis was performed in male patients and revealed that HDL-C (β = 0.191, p = 0.002), heart rate (β = 0.182, p = 0.004), SBP (β = 0.167, p = 0.007), LVMI (β = 0.132, p = 0.032), and LAD (β = 0.165, p = 0.009) were independently associated with increasing FFA levels.

Conclusions

In patients with HCM, LVMI, LAD, HDL-C, SBP, and heart rate were independently associated with increasing plasma FFA levels in males, whereas not in females. These results suggest that sex may affect the pathogenesis of HCM through influencing FFA metabolism. And these sex-related differences should be taken into account in therapeutic approaches to influence myocardial FFA metabolism in HCM.

Neonatal fatty acid status and cardiometabolic health at 9years

BACKGROUND

Long chain polyunsaturated fatty acid (LCPUFA) status is associated with risk of cardiovascular diseases in adulthood. We previously demonstrated no effect of LCPUFA supplementation after birth on BP and anthropometrics. Little is known about the association between fatty acid status at birth and cardiometabolic health at older ages.

AIM

To evaluate associations between docosahexaenoic acid (DHA) and arachidonic acid (AA) levels in the umbilical cord and blood pressure (BP) and anthropometrics at 9years.

STUDY DESIGN

Observational follow-up study. Multivariable analyses were carried out to adjust for potential confounders.

SUBJECTS

229 children who took part in a randomized controlled trial (RCT) on the effects of LCPUFA formula supplementation.

OUTCOME MEASURES

BP was chosen as primary outcome; heart rate and anthropometrics as secondary outcomes.

RESULTS

AA levels in the wall of the umbilical vein and artery were negatively associated with diastolic BP (B: vein -0.831, 95% CI: -1.578; -0.083, p=0.030; artery: -0.605, 95% CI: -1.200; -0.010, p=0.046). AA was not associated with systolic BP; DHA not with diastolic nor systolic BP. The AA:DHA ratio in the umbilical vein was negatively associated with diastolic BP (B: -1.738, 95% CI: -3.141; -0.335, p=0.015). Heart rate and anthropometrics were not associated with neonatal LCPUFA status.

CONCLUSIONS

Higher AA levels and a higher AA:DHA ratio at birth are associated with lower diastolic BP at age 9. This suggests that the effect of LCPUFAs at early age is different from that in adults, where DHA is regarded anti-adipogenic and AA as adipogenic.

Differentiation in vitro of omental and subcutaneous pre-adipocytes from Spanish Lacha and Rasa Aragonesa sheep

Factors responsible for breed- and depot-specific differences in the development of lipogenic enzymes, and hence lipogenic capacity of adipocytes, in sheep adipose tissue have been investigated using a serum-free cell culture system. Effects of insulin, tri-iodothyronine and exogenous lipid on the development in vitro of the lipogenic enzymes glycerol 3-phosphate dehydrogenase (G3PDH), fatty acid synthetase (FAS), NADP-malate dehydrogenase (ME), glucose 6-phosphate dehydrogenase (G6PDH), and isocitrate dehydrogenase (ICDH) in omental and subcutaneous pre-adipocytes from Lacha and Rasa Aragonesa lambs were investigated. Addition of insulin plus tri-iodothyronine caused pre-adipocyte differentiation, which was enhanced by addition of a lipid supplement. G3PDH activities achieved by differentiation of pre-adipocytes in vitro were similar to those found in vivo; furthermore after differentiation in vitro adipocytes from Rasa Aragonesa lambs had a greater G3PDH activity than adipocytes from Lacha lambs, as found in vivo. In contrast activities of FAS, G6PDH and ME achieved by differentiation in vitro were much greater than those found previously in vivo. While breed- and depot-specific changes in G6PDH observed after differentiation in vitro were similar to those observed in vivo, changes in FAS induced in vitro differed from those found during development in vivo. The study shows that pre-adipocytes from Rasa Aragonesa and Lacha lambs have intrinsic depot- and breed-specific differences in their ability to differentiate and express lipogenic enzymes. The combination of insulin, tri-iodothyronine and a lipid supplement appears to be sufficient to account for in vivo G3PDH activities but other factors are required to explain activities of FAS, G6PDH and ME found in vivo.

An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity

In the past three decades, total fat and saturated fat intake as a percentage of total calories has continuously decreased in Western diets, while the intake of omega-6 fatty acid increased and the omega-3 fatty acid decreased, resulting in a large increase in the omega-6/omega-3 ratio from 1:1 during evolution to 20:1 today or even higher. This change in the composition of fatty acids parallels a significant increase in the prevalence of overweight and obesity. Experimental studies have suggested that omega-6 and omega-3 fatty acids elicit divergent effects on body fat gain through mechanisms of adipogenesis, browning of adipose tissue, lipid homeostasis, brain-gut-adipose tissue axis, and most importantly systemic inflammation. Prospective studies clearly show an increase in the risk of obesity as the level of omega-6 fatty acids and the omega-6/omega-3 ratio increase in red blood cell (RBC) membrane phospholipids, whereas high omega-3 RBC membrane phospholipids decrease the risk of obesity. Recent studies in humans show that in addition to absolute amounts of omega-6 and omega-3 fatty acid intake, the omega-6/omega-3 ratio plays an important role in increasing the development of obesity via both AA eicosanoid metabolites and hyperactivity of the cannabinoid system, which can be reversed with increased intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). A balanced omega-6/omega-3 ratio is important for health and in the prevention and management of obesity.

Effects of polyunsaturated fatty acid intake and status during pregnancy, lactation, and early childhood on cardiometabolic health: A systematic review

The importance of polyunsaturated fatty acid (PUFA) intake in fetal life and infancy has been widely studied in relation to child cognitive and visual development, but whether early life PUFA exposure is related to cardiometabolic risk factors is unclear. The focus of this systematic review was to evaluate the effects of PUFA dietary intake and blood levels during pregnancy, lactation, or early childhood (⩽5 y) on obesity, blood pressure, blood lipids, and insulin sensitivity. We identified 4302 abstracts in the databases Embase, Medline and Cochrane Central (April 2014), of which 56 articles, reporting on 45 unique studies, met all selection criteria. Many of the included studies focused on obesity as an outcome (33 studies), whereas studies on insulin sensitivity were relatively scarce (6 studies). Overall, results for obesity, blood pressure, and blood lipids were inconsistent, with a few studies reporting effects in opposite directions and other studies that did not observe any effects of PUFAs on these outcomes. Four studies suggested beneficial effects of PUFAs on insulin sensitivity. We conclude that there is insufficient evidence to support a beneficial effect of PUFAs in fetal life or early childhood on obesity, blood pressure, or blood lipids. More research is needed to investigate the potential favorable effects of PUFAs on insulin sensitivity, and to examine the role of specific fatty acids in early life on later cardiometabolic health.

Age-related obesity is a heritage of the evolutionary past

In the process of human aging, an increase in the total amount of fat is observed mainly due to accumulation of lipids in non-adipose tissues. Insulin resistance, provoked by the intracellular accumulation of triglycerides, is often associated with development of such age-related diseases as atherosclerosis, type 2 diabetes, cancer, osteoporosis, and also with systemic inflammation and lipo- and glucose toxicity. Accumulation of lipids and lipophilic compounds is a biological phenomenon common for both prokaryotes and eukaryotes. Initially, it arose as an adaptation to starvation and shortage of nitrogen-containing nutrients, but later it converted into a depot of membrane material, needed on recommencement of cell division. In rodents and humans, the accumulation of non-metabolized fat in non-adipose tissues can be regarded as an adaptation to changes in the internal medium on a certain stage of ontogenesis as a result of age-related dysfunction of adipose tissue.

A prospective study of erythrocyte polyunsaturated fatty acid, weight gain, and risk of becoming overweight or obese in middle-aged and older women

PURPOSE

ω3 and ω6 fatty acids (FA) may have divergent effects on the development of obesity. We examined the association of baseline erythrocyte ω3 and ω6 FA composition with body weight change and the risk of becoming overweight or obese in the Women's Health Study (WHS) participants.

METHODS

We identified 534 women who had baseline erythrocyte FA measured and a baseline body mass index (BMI) of 18.5-<25 kg/m(2). Body weight was updated at a total of six time points during follow-up.

RESULTS

Weight gain during a mean of 10.4-year follow-up increased with increasing quartiles of baseline erythrocyte cis ω6 FA, ω6/ω3 ratio, and trans FA while decreased with increasing cis ω3 FA. After multivariable adjustment including total energy intake and physical activity, the weight gain (kg) in the highest versus the lowest quartile was 3.08 versus 2.32 for erythrocyte cis ω6 FA (p trend 0.04), 2.07 versus 2.92 for cis ω3 FA (p trend 0.08), 2.93 versus 2.05 for ω6/ω3 ratio (p trend 0.046), and 3.03 versus 2.27 for trans FA (p trend 0.06). Among individual FA, the associations were significant for 18:2ω6, 18:3ω6, and trans 18:1 and marginally significant for 20:3ω6 and trans 18:2. The risk of becoming overweight or obese (defined as BMI ≥25 kg/m(2) at any follow-up time point) increased across increasing ω6/ω3 ratio (multivariable model p trend 0.04).

CONCLUSIONS

In this prospective study, we found suggestive evidence that erythrocyte cis ω6 FA may be positively associated, and cis ω3 FA inversely associated with weight gain in initially normal-weight women.

Adipose triglyceride lipase regulates lipid metabolism in dairy goat mammary epithelial cells

Adipose triglyceride lipase (ATGL) catalyzes the initial step in the lipid lipolysis process, hydrolyzing triglyceride (TG) to produce diacylglycerol (DG) and free fatty acids (FFA). In addition, ATGL regulates lipid storage and release in adipocyte cells. However, its role in mammary gland tissue remains unclear. To assess the role of the ATGL gene in the goat mammary gland, this study analyzed the tissue distribution and expression of key genes together with lipid accumulation after knockdown of the ATGL gene. The mRNA of ATGL was highly expressed in subcutaneous adipose tissue, the lung and the mammary gland with a significant increase in expression during the lactation period compared with the dry period of the mammary gland. Knockdown of the ATGL gene in goat mammary epithelial cells (GMECs) using siRNA resulted in a significant decrease in both ATGL mRNA and protein levels. Silencing of the ATGL gene markedly increased lipid droplet accumulation and intracellular TG concentration (P<0.05), while it reduced FFA levels in GMECs (P<0.05). Additionally, the expression of HSL for lipolysis, FABP3 for fatty acid transport, PPARα for fatty acid oxidation, ADFP, BTN1A1, and XDH for milk fat formation and secretion was down-regulated (P<0.05) after knockdown of the ATGL gene, with increased expression of CD36 for fatty acid uptake (P<0.05). In conclusion, these data suggest that the ATGL gene plays an important role in triglyceride lipolysis in GMECs and provides the first experimental evidence that ATGL may be involved in lipid metabolism during lactation.

Physiological functions of peroxisome proliferator-activated receptor β

The peroxisome proliferator-activated receptors, PPARα, PPARβ, and PPARγ, are a family of transcription factors activated by a diversity of molecules including fatty acids and fatty acid metabolites. PPARs regulate the transcription of a large variety of genes implicated in metabolism, inflammation, proliferation, and differentiation in different cell types. These transcriptional regulations involve both direct transactivation and interaction with other transcriptional regulatory pathways. The functions of PPARα and PPARγ have been extensively documented mainly because these isoforms are activated by molecules clinically used as hypolipidemic and antidiabetic compounds. The physiological functions of PPARβ remained for a while less investigated, but the finding that specific synthetic agonists exert beneficial actions in obese subjects uplifted the studies aimed to elucidate the roles of this PPAR isoform. Intensive work based on pharmacological and genetic approaches and on the use of both in vitro and in vivo models has considerably improved our knowledge on the physiological roles of PPARβ in various cell types. This review will summarize the accumulated evidence for the implication of PPARβ in the regulation of development, metabolism, and inflammation in several tissues, including skeletal muscle, heart, skin, and intestine. Some of these findings indicate that pharmacological activation of PPARβ could be envisioned as a therapeutic option for the correction of metabolic disorders and a variety of inflammatory conditions. However, other experimental data suggesting that activation of PPARβ could result in serious adverse effects, such as carcinogenesis and psoriasis, raise concerns about the clinical use of potent PPARβ agonists.

Maternal prepregancy BMI and lipid profile during early pregnancy are independently associated with offspring's body composition at age 5-6 years: the ABCD study

BACKGROUND

There is growing evidence that disturbances in maternal metabolism and, subsequently, intrauterine conditions affect foetal metabolism. Whether this has metabolic consequences in offspring later in life is not fully elucidated. We investigated whether maternal pre-pregnancy body mass index (pBMI) is associated with offspring's adiposity at age 5-6 years and whether this association is mediated by the mother's lipid profile during early pregnancy.

METHODS

Data were derived from a multi-ethnic birth cohort, the Amsterdam Born Children and their Development (ABCD) study (inclusion 2003-2004). During early gestation mothers completed a questionnaire during pregnancy (pBMI) and random non-fasting blood samples were analysed for total cholesterol (TC), triglycerides (TG), apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB) and total free fatty acids (FFA) in early gestation. At age 5-6 years, child's BMI, waist-to-height-ratio (WHtR) and fat% were assessed.

RESULTS

Only non-diabetic mothers with at term-born children were included (n = 1727). Of all women, 15.1% were overweight(BMI: 25-29.9 kg/m2) and 4.3% were obese (BMI≥30 kg/m2). After adjustments for confounders, every unit increase in pBMI was linearly associated with various offspring variables: BMI (β 0.10; 95% CI 0.08-0.12), WHtR*100 (β 0.13; 95% CI 0.09-0.17), fat% (β 0.21; 95% CI 0.13-0.29) and increased risk for overweight (OR:1.15; 95% CI 1.10-1.20). No convincing proof for mediation by maternal lipid profile during early gestation was found. Moreover, maternal FFA was associated with the child's fat percentage, BMI and risk for overweight. Maternal ApoB and TC were positively associated with the offspring's fat percentage and maternal TG was positively associated with their children's WHtR.

CONCLUSIONS

Both pBMI and maternal lipids during early pregnancy are independently related to offspring adiposity.

Inhibitory effects of tannic acid on fatty acid synthase and 3T3-L1 preadipocyte

Tannic acid is a hydrolyzable tannin that exists in many widespread edible plants with a variety of biological activities. In this study, we found that tannic acid potently inhibited the activity of fatty acid synthase (FAS) in a concentration-dependent manner with a half-inhibitory concentration value (IC50) of 0.14 microM. The inhibition kinetic results showed that the inhibition of FAS by tannic acid was mixed competitive and noncompetitive manner with respect to acetyl-CoA and malonyl-CoA, but uncompetitive to NADPH. Tannic acid prevented the differentiation of 3T3-L1 pre-adipocytes, and thus repressed intracellular lipid accumulation. In the meantime, tannic acid decreased the expression of FAS and down-regulated the mRNA level of FAS and PPARgamma during adipocyte differentiation. Further studies showed that the inhibitory effect of tannic acid did not relate to FAS non-specific sedimentation. Since FAS was believed to be a therapeutic target of obesity, these findings suggested that tannic acid was considered having potential in the prevention of obesity.

The lipid fraction of human milk initiates adipocyte differentiation in 3T3-L1 cells

BACKGROUND

The prevalence of childhood obesity has increased worldwide over the past decade. Despite evidence that human milk lowers the risk of childhood obesity, the mechanism is not fully understood.

AIMS

We investigated the direct effect of human milk on differentiation of 3T3-L1 preadipocytes.

STUDY DESIGN AND SUBJECTS

3T3-L1 preadipocytes were treated with donated human milk only or the combination of the standard hormone mixture; insulin, dexamethasone (DEX), and 3-isobututyl-1-methylxanthine (IBMX). Furthermore, the induction of preadipocyte differentiation by extracted lipids from human milk was tested in comparison to the cells treated with lipid extracts from infant formula. Adipocyte differentiation, specific genes as well as formation of lipid droplets were examined.

RESULTS

We clearly show that lipids present in human milk initiate 3T3-L1 preadipocyte differentiation. In contrast, this effect was not observed in response to lipids present in infant formula. The initiation of preadipocyte differentiation by human milk was enhanced by adding the adipogenic hormone, DEX or insulin. The expression of late adipocyte markers in Day 7 adipocytes that have been induced into differentiation with human milk lipid extracts was comparable to those in control cells initiated by a standard adipogenic hormone cocktail.

CONCLUSIONS

These results demonstrate that human milk contains bioactive lipids that can initiate preadipocyte differentiation in the absence of the standard adipogenic compounds via a unique pathway.

Adipose triglyceride lipase (ATGL) clone, expression pattern, and regulation by different lipid sources and lipid levels in large yellow croaker (Pseudosciaena crocea R.)

Adipose triglyceride lipase (ATGL) was recently identified as a triglyceride (TG)-specific lipase. In this study, we first obtained from large yellow croaker fish a 1,820-bp (GenBank ID: HQ916211) ATGL cDNA fragment with a 141-bp 5'UTR, a 1,485-bp open reading frame, and a 194-bp 3'UTR. The predicted fish ATGL had 494 amino acids (GenBank ID: ADY89608) and a calculated molecular weight of 55.1 kDa. ATGL was highly expressed in liver and, to a lesser degree, in heart, muscle, and abdominal fat. ATGL gene expression was high at 4.5 g and then decreased at 157.9 g and increased again at 474.2 g. The effects of lipid levels and lipid sources on ATGL expression in vivo were also investigated. A high-lipid diet decreased ATGL expression in fish significantly (P < 0.01). Fish in soybean oil group exhibited significantly lower ATGL expression than fish in the fish oil and beef tallow groups (P < 0.01). These data enhance our understanding of ATGL in fish lipid metabolism.

Co-treatment with dexamethasone and octanoate induces adipogenesis in 3T3-L1 cells

We report here that octanoate, a medium chain fatty acid, induces adipocyte differentiation in 3T3-L1 cells by co-treatment with dexamethasone, although octanoate has been known not to stimulate 3T3-L1 adipogenesis. A low concentration of exogenous glucose prevented 3T3-L1 adipogenesis induced by 1-methyl 3-isobutylxanthine, dexamethasone, and insulin (MDI) treatment (a common protocol for adipocyte differentiation). In contrast, co-treatment with dexamethasone and octanoate (D-OCT) induced adipogenesis under the same conditions. These findings imply that octanoate, rather than glucose, is the source of accumulated lipids in D-OCT-induced adipogenesis. D-OCT increased expression of the differentiation markers peroxisome proliferator-activated receptor (PPAR)gamma2 and caveolin-1. A specific inhibitor of p38 mitogen-activated protein (MAP) kinase inhibited D-OCT-induced adipogenesis. These results suggest that the p38 MAP kinase pathway followed by up-regulation of PPARgamma2 may be involved in 3T3-L1 adipocyte differentiation induced by D-OCT, as well as by MDI.

Effect of dietary fat or starch supply during gestation and/or lactation on the performance of sows, piglets' survival and on the performance of progeny after weaning

Two trials were carried out to compare the effects of fat or starch inclusion in sow's diet on sow and litter performance. In each trial, sows were assigned to one of two treatments. In trial 1, the sows were fed diets containing either soybean oil (5%, treatment GL5) or cornstarch (11.3%, GL0) from day 35 of gestation to weaning. Daily net energy and nutrient allowance were equalised during gestation. In trial 2, the same treatments were applied only after farrowing (treatments L5 and L0, respectively). Within each trial, a batch of piglets was studied until slaughter. In trial 1, adipose cell development and total lipid content were determined on some pigs at weaning (n = 6/treatment) and at slaughter in dorsal subcutaneous adipose tissue (n = 13/group at least) and in muscle (n = 46/group at least). Piglets' birth weight was not affected by treatment in trial 1. Survival rates at birth and after 24 h of life were higher in treatment GL5 (4.0% v. 7.5% stillborn piglets in GL0 treatment, P < 0.05; 8.7% v. 12.6% of piglets alive at 24 h of age died in treatment GL0, P = 0.06). Subsequently, overall survival rate until weaning was higher in treatment GL5 (81.4% v. 75.7% of total born piglets, P = 0.03), but litter size at weaning was not significantly affected (11.3). Litter growth rate before weaning was increased when a fat-enriched diet was provided during gestation and lactation (+140 g/day per litter; P < 0.01) and to a lower extent when provided only after farrowing (+90 g/day; P < 0.05). Energy supply through fat did not decrease the mobilisation of the sow's body reserve and backfat thickness loss was even higher with treatment GL5 (P < 0.05). After weaning, pigs' average daily gain, feed : gain ratio and carcass lean content were not affected by the energy source supplied before and/or after farrowing. At weaning, the number of adipose cells in the dorsal subcutaneous adipose tissue and in the Longissimus dorsi muscle was higher in the GL5 pigs. Muscle lipid content at weaning did not differ between treatments, but it was higher at slaughter, around 110 kg, in the GL5 pigs (3.46% v. 2.58%, P < 0.001).

Size and phospholipid coating of lipid droplets in the diet of young mice modify body fat accumulation in adulthood

BACKGROUND

In addition to contemporary lifestyle factors that contribute to the increased obesity prevalence worldwide, early nutrition is associated with sustained effects on later life obesity. We hypothesized that physical properties of dietary lipids contribute to this nutritional programming. We developed a concept infant formula (IMF) with large, phospholipid-coated lipid droplets (Nuturis; Danone Research, Paris, France) and investigated its programming effect on metabolic phenotype later in life.

METHODS

Male C57Bl/6j mice were fed a control formula (Control IMF) or Nuturis (Concept IMF) diet between postnatal day (PN)16 and PN42. All mice were subsequently fed a Western-style diet (WSD) until PN126. Body composition was monitored repeatedly by dual-energy X-ray absorptiometry between PN42 and PN126.

RESULTS

Concept IMF slightly increased lean body mass as compared with Control IMF at PN42 but did not affect fat mass. Upon 84 d of WSD feeding, the Concept IMF group showed reduced fat accumulation as compared with Control IMF. In addition, fasting plasma leptin, resistin, glucose, and lipids were significantly lower in the Concept IMF group.

CONCLUSION

Large phospholipid-coated lipid droplets in young mice reduced fat accumulation and improved metabolic profile in adulthood. These data emphasize that physical properties of early dietary lipids contribute to metabolic programming.

Palmitate enhances the differentiation of mouse embryonic stem cells towards white adipocyte lineages

The number of adipocyte progenitors is determined early in foetal and neonatal development in a process which may be altered by gender and excess nutrient intake, and which in turn determines fat mass in adulthood and the risk of developing obesity. Here we investigate the hypothesis that excess nutrients, in this case the long chain fatty acid palmitate, can program differentiating stem cells towards white fat lineages. The experiments were performed on mouse embryonic stem cells in chemically defined media (CDM) supplemented with bone morphogenetic protein 4 (BMP4) and all trans-retinoic acid (RA). Subsequent treatment for 21 days with palmitate not only promoted the expression of adipocyte markers and monolocular lipid deposition as observed by RT/QPCR and immunocytochemistry, but also stimulated a considerable enrichment in adipocytes as measured by flow cytometry and a lipolytic response to catecholamines. Palmitate increased protein levels of adiponectin that is preferentially expressed in subcutaneous fat, while inhibiting IGFBP2 and IGFBP3 that are associated with visceral fat. In keeping with this finding, palmitate also increased expression of the subcutaneous markers Shox2 and Twist1 and oestrogenising enzymes. Collectively, these results suggest that palmitate induces differentiation towards subcutaneous fat and that this could occur through its oestrogenising effects on the preadipocyte, suggesting a role for palmitate in programming fat development towards a metabolically favourable profile.

Effect ofn-3 long chain polyunsaturated fatty acids during the perinatal period on later body composition

A systematic review to identify studies reporting the effects ofn-3 long chain polyunsaturated fatty acids (LCPUFA) intake, during pregnancy and postnatally, on infants and young children's body composition was performed. A structured search strategy was performed in the MEDLINE (PubMed), EMBASE, and LILACS databases. Inclusion and exclusion criteria were defined according to the research question. Only those studies addressing the relationship betweenn-3 LCPUFA exposure during the perinatal period and later adiposity measured in terms of weight, height, body mass index (BMI), skinfold thickness and/or circumferences were included regardless of the study design. Studies quality was scored and were thereafter categorised into those reporting on maternal intake ofn-3 LCPUFA during pregnancy or lactation (6 publications) or on infant'sn-3 LCPUFA intake (7 publications). Two studies showed inverse associations between maternaln-3 LCPUFA intake and children's later body composition (lower adiposity, BMI or body weight), two showed direct associations and no effects were observed in the remaining two studies. Among those studies focusing onn-3 LCPUFA intake through enriched infant formulas; three observed no effect on later body composition and two showed higher weight and adiposity with increased amounts ofn-3 LCPUFA. Reversely, in two studies weight and fat mass decreased. In conclusion, reported body composition differences in infants and young children were not clearly explained by perinataln-3 LCPUFA intake via supplemented formulas, breastfeeding or maternal intakes ofn-3 LCPUFA during pregnancy and lactation. Associated operational mechanisms includingn-3 LCPUFA doses and sources applied are not sufficiently explained and therefore no conclusions could be made.

In vivo NMR detection of diet-induced changes in adipose tissue composition

We introduce an in vivo spectroscopic method to assess the effects of diet on fatty acid composition of the predominant chemical constituent of adipocytes in mice. To do this, we make use of a nonlinear NMR signal that, unlike a standard NMR signal, is intrinsically insensitive to local magnetic field inhomogeneities and which naturally suppresses the large water signal from nonfatty tissues. Our method yields fat composition information from fat depots distributed over large sample volumes in a single experiment, without requiring the use of tedious shimming procedures, voxel selection, or water suppression. Our results suggest that this method can reveal clear differences in adipose tissue composition of mice fed a standard chow diet compared with mice fed a diet rich in polyunsaturated fatty acids. With further developments this method could be used to obtain information on human lipid composition noninvasively and to track changes in lipid composition induced by diet intervention, pharmaceutical drugs, and exercise.

Development of intramuscular fat in Wagyu beef cattle depends on adipogenic or antiadipogenic substances present in serum

In blood, there are many kinds of adipogenic or antiadipogenic factors such as hormones and vitamins. In this study, adipogenic activity in sera of fattened beef cattle was evaluated using cultured mouse 3T3-L1 preadipocytes. After the preadipocytes were grown to reach confluence, serum of fattened beef cattle was added into the culture medium (10%, vol/vol)for 3 days, and thereafter cellular sn-glycerol-3-phosphate dehydrogenase (GPDH) activity was determined as an index ofadipocyte differentiation. Sera were collected from 19 beef cattle (Wagyu and Wagyu × Holstein cross cattle) from three different farms at slaughter. Cellular GPDH activity was significantly different among the farms, and was affected by sex difference (i.e. sera from fattened heifers induced higher GPDH activity than those from steers). There was a positive correlation between GPDH activity and beef marbling performance (T = 0·62, P < 0·02), suggesting that serum factor(s) play a role in development of intramuscular fat deposition. Adipogenic activity was negatively correlated with serum retinol concentration (r = −0·73, P < 0·001). Neither serum cholesterol, triacylglycerol nor non-esterified fatty acid was related to adipogenic activity.

Furthermore, serum retinol concentration was negatively correlated with beef marbling performance. These data imply that retinol level in blood during the fattening period may influence intramuscular fat deposition of beef cattle through its antiadipogenic action on preadipocytes present in muscle tissues.

Differential expression of FABP 3, 5, 7 in infantile and adult monkey cerebellum

To clarify the involvement of fatty acid binding proteins (FABPs) in cerebellar development and function, we explored the distribution of three brain-expressed FABPs, FABP 3, 5 and 7, by comparing three animal groups--infantile, normal and postischemic adult monkeys. Immunoblotting analysis revealed intense expression of FABP 3 and 7, but not of FABP5, in the control and postischemic adult cerebellum. The protein levels of FABP7, but not of FABP 3 or 5, gradually increased until 2 weeks after the insult. Immunohistochemical analysis showed that cerebellar FABP3-positive cells were Purkinje cells and Bergmann glia. FABP5-positive cells were found only in the postischemic cerebellum, and were identified as activated microglia. Interestingly, in the infantile cerebellum, both the granule cell progenitors in the external granular layer (EGL) and the oligodendrocyte progenitors in the internal granular layer (IGL) expressed FABP5. In the adult cerebellum, FABP7 was expressed in Purkinje cells and basket interneurons, while in the infantile cerebellum it was also found in Bergmann glia. These results showed differential expression of FABPs in cerebellar neuronal and glial cell types; FABP 3 and 7 were predominantly expressed in normal cerebellum, FABP5 after ischemic injury, while FABP 3, 5 and 7 were expressed during cerebellar development.