Altered expression of genes involved in lipid metabolism in obese subjects with unfavourable phenotype

Obesity Increases Gene Expression of Markers Associated With Immunosenescence in Obese Middle-Aged Individuals

Recently, it has been argued that obesity leads to a chronic pro-inflammatory state that can accelerate immunosenescence, predisposing to the early acquisition of an immune risk profile and health problems related to immunity in adulthood. In this sense, the present study aimed to verify, in circulating leukocytes, the gene expression of markers related to early immunosenescence associated with obesity and its possible relationships with the physical fitness in obese adults with type 2 diabetes or without associated comorbidities. The sample consisted of middle-aged obese individuals (body mass index (BMI) between 30-35 kg/m²) with type 2 diabetes mellitus (OBD; n = 17) or without associated comorbidity (OB; n = 18), and a control group of eutrophic healthy individuals (BMI: 20 - 25 kg/m²) of same ages (E; n = 18). All groups (OBD, OB and E) performed the functional analyses [muscle strength (1RM) and cardiorespiratory fitness (VO_2max)], anthropometry, body composition (Air Displacement Plethysmograph), blood collections for biochemical (anti-CMV) and molecular (gene expression of leptin, IL-2, IL-4, IL-6, IL-10, TNF-α, PD-1, P16^ink4a, CCR7, CD28 and CD27) analyses of markers related to immunosenescence. Increased gene expression of leptin, IL-2, IL-4, IL-10, TNF-α, PD-1, P16^ink4a, CCR7 and CD27 was found for the OBD and OB groups compared to the E group. Moreover, VO_2max for the OBD and OB groups was significantly lower compared to E. In conclusion, obesity, regardless of associated disease, induces increased gene expression of markers associated with inflammation and immunosenescence in circulating leukocytes in obese middle-aged individuals compared to a eutrophic group of the same age. Additionally, increased adipose tissue and markers of chronic inflammation and immunosenescence were associated to impairments in the cardiorespiratory capacity of obese middle-aged individuals.

Distinct whole-blood transcriptome profile of children with metabolic healthy overweight/obesity compared to metabolic unhealthy overweight/obesity

BACKGROUND

Youth populations with overweight/obesity (OW/OB) exhibit heterogeneity in cardiometabolic health phenotypes. The underlying mechanisms for those differences are still unclear. This study aimed to analyze the whole-blood transcriptome profile (RNA-seq) of children with metabolic healthy overweight/obesity (MHO) and metabolic unhealthy overweight/obesity (MUO) phenotypes.

METHODS

Twenty-seven children with OW/OB (10.1 ± 1.3 years, 59% boys) from the ActiveBrains project were included. MHO was defined as having none of the following criteria for metabolic syndrome: elevated fasting glucose, high serum triglycerides, low high-density lipoprotein-cholesterol, and high systolic or diastolic blood pressure, while MUO was defined as presenting one or more of these criteria. Inflammatory markers were additionally determined. Total blood RNA was analyzed by 5'-end RNA-sequencing.

RESULTS

Whole-blood transcriptome analysis revealed a distinct pattern of gene expression in children with MHO compared to MUO children. Thirty-two genes differentially expressed were linked to metabolism, mitochondrial, and immune functions.

CONCLUSIONS

The identified gene expression patterns related to metabolism, mitochondrial, and immune functions contribute to a better understanding of why a subset of the population remains metabolically healthy despite having overweight/obesity.

IMPACT

A distinct pattern of whole-blood transcriptome profile (RNA-seq) was identified in children with metabolic healthy overweight/obesity (MHO) compared to metabolic unhealthy overweight/obesity (MUO) phenotype. The most relevant genes in understanding the molecular basis underlying the MHO/MUO phenotypes in children could be: RREB1, FAM83E, SLC44A1, NRG1, TMC5, CYP3A5, TRIM11, and ADAMTSL2. The identified whole-blood transcriptome profile related to metabolism, mitochondrial, and immune functions contribute to a better understanding of why a subset of the population remains metabolically healthy despite having overweight/obesity.

Obesity, metabolic health and omics: Current status and future directions

The growing obesity epidemic is becoming a major public health concern, and the associated costs represent a considerable burden on societies. Among the most common complications of severe obesity are the development of hypertension, dyslipidemia, type 2 diabetes, cardiovascular disease, and various types of cancer. Interestingly, some obese individuals have a favorable metabolic profile and appear to be somehow protected from the detrimental effects of excessive adipose tissue accumulation. These individuals remain normoglycemic, insulin sensitive, and hypotensive with proper blood lipid levels, despite their high body mass index and/or waist circumference. Multiple independent observations have led to the concept of the metabolically healthy obese (MHO) phenotype, yet no consensus has been reached to date regarding a universal definition or the main mechanism behind this phenomenon. Recent technological advances and the use of high-throughput analysis techniques have revolutionized different areas of biomedical research. A multi-omics approach, which is used to investigate changes at different molecular levels in an organism or tissue, may provide valuable insights into the interplay between the molecules or pathways and the roles of different factors involved in the mechanisms underlying metabolic health deterioration. The aim of this review is to present the current status regarding the use of omics technologies to investigate the MHO phenotype, as well as the results of targeted analyses conducted in MHO individuals.

Gender dependent differences in lipid metabolism in individuals with type 2 diabetes mellitus

Aim

The present study investigates gender dependent effects of insulin resistance on lipid profile and adipocytokines in individuals with diabetes receiving oral antidiabetic drugs (OADs). The aim was also to reveal the changes in the expression of genes involved in lipid metabolism and inflammation.

Methods

Lipid profile, adipocytokine levels and homeostatic model assessment of insulin resistance (HOMA-IR) was assessed in 100 patients with diabetes (M = 43, F = 57) matched for age and gender with healthy individuals (M = 45, F = 55). The expression pattern of genes was analyzed by quantitative real time PCR.

Results

Males consuming metformin with other drugs exhibited a positive association between HOMA-IR and cholesterol, triglyceride and very low density lipoprotein (VLDL). Females consuming only metformin and metformin with other drugs, showed a positive association of HOMA-IR with cholesterol and a negative association with adiponectin. In males and females with diabetes, a comparable expression of peroxisome proliferator activated receptor γ (PPARγ) while higher expression of sterol regulatory element binding protein 1 (SREBP1) was observed. Expression of fatty acid synthase (FAS), long chain acyl CoA Synthetases (ACSL), malonyl-CoA-acyl carrier protein transacylase (MCAT) and nuclear factor kappa β (NFkβ) was higher in men with diabetes than healthy males. Expression of tumor necrosis factor α (TNF-α) was higher in males and females with diabetes than respective healthy genders.

Conclusion

Insulin resistance adversely affects lipid profile, adipocytokines in males with type 2 diabetes. Expression of genes involved in lipid metabolism and inflammation is found to be undesirably and differentially altered in both the genders.

An Overview of the Role of Adipokines in Cardiometabolic Diseases

Obesity as an independent risk factor for cardiovascular diseases (CVDs) leads to an increase in morbidity, mortality, and a shortening of life span. The changes in heart structure and function as well as metabolic profile are caused by obese people, including those free of metabolic disorders. Obesity alters heart function structure and affects lipid and glucose metabolism, blood pressure, and increase inflammatory cytokines. Adipokines, specific cytokines of adipocytes, are involved in the progression of obesity and the associated co-morbidities. In the current study, we review the scientific evidence on the effects of obesity on CVDs, focusing on the changes in adipokines. Several adipokines have anti-inflammatory and cardioprotective effects comprising omentin, apelin, adiponectin, and secreted frizzled-related protein (Sfrp-5). Other adipokines have pro-inflammatory impacts on the cardiovascular system and obesity including leptin, tumor necrosis factor (TNF), retinol-binding protein4 (RBP-4), visfatin, resistin, and osteopontin. We found that obesity is associated with multiple CVDs, but can only occur in unhealthy metabolic patients. However, more studies should be designed to clarify the association between obesity, adipokine changes, and the occurrence of CVDs.

Exploring Therapeutic Targets to Reverse or Prevent the Transition from Metabolically Healthy to Unhealthy Obesity

The prevalence of obesity and obesity-related metabolic comorbidities are rapidly increasing worldwide, placing a huge economic burden on health systems. Excessive nutrient supply combined with reduced physical exercise results in positive energy balance that promotes adipose tissue expansion. However, the metabolic response and pattern of fat accumulation is variable, depending on the individual’s genetic and acquired susceptibility factors. Some develop metabolically healthy obesity (MHO) and are resistant to obesity-associated metabolic diseases for some time, whereas others readily develop metabolically unhealthy obesity (MUO). An unhealthy response to excess fat accumulation could be due to susceptibility intrinsic factors (e.g., increased likelihood of dedifferentiation and/or inflammation), or by pathogenic drivers extrinsic to the adipose tissue (e.g., hyperinsulinemia), or a combination of both. This review outlines the major transcriptional factors and genes associated with adipogenesis and regulation of adipose tissue homeostasis and describes which of these are disrupted in MUO compared to MHO individuals. It also examines the potential role of pathogenic insulin hypersecretion as an extrinsic factor capable of driving the changes in adipose tissue which cause transition from MHO to MUO. On this basis, therapeutic approaches currently available and emerging to prevent and reverse the transition from MHO to MUO transition are reviewed.

Fatty acid profile and estimated desaturase activities in whole blood are associated with metabolic health

BACKGROUND

The aim was to investigate if fatty acid profile and estimated desaturase activities; stearoyl CoA-desaturase (SCD), delta-5-desaturase and delta-6-desaturase (D5D; D6D), differ between individuals with metabolically healthy (MH) and unhealthy (MU) phenotypes. We also explored these associations according to BMI categories.

METHODS

Men and women at moderately elevated risk of cardiovascular disease were included in this cross-sectional study (n = 321). If subjects met ≥4 out of 5 criteria (elevated triglycerides, total and LDL-cholesterol, HbA1c and low HDL-cholesterol), they were classified as MU (n = 52). If levels were within reference ranges for ≥3 of the same criteria, subjects were classified as MH (n = 150). Utilizing the entire population, a score ranging from 0 to 5 denoting the number of MU criteria met was computed. Estimated desaturase activities were calculated as product-to-precursor ratio of fatty acids in whole blood (SCD16 [16:1n7/16:0], SCD18 [18:1n9/18:0], D5D [18:3n6/18:2n6], D6D [20:4n6/20:3n6]).

RESULTS

Individuals with MH had lower estimated SCD16 and SCD18 activities, whereas estimated D6D activity was higher compared to MU. Similar, SCD16 and SCD18 increased, whereas D6D decreased with increasing criteria of MU. Trends were similar across BMI categories.

CONCLUSIONS

This study supports the notion of estimated desaturase activities as possible novel biomarkers of metabolic health irrespectively of BMI.

A comprehensive metabolic profiling of the metabolically healthy obesity phenotype

BACKGROUND

The ever-increasing prevalence of obesity constitutes a major health problem worldwide. A subgroup of obese individuals has been described as "metabolically healthy obese" (MHO). In contrast to metabolically unhealthy obese (MUO), the MHO phenotype has a favorable risk profile. Despite this, the MHO phenotype is still sub-optimally characterized with respect to a comprehensive risk assessment. Our aim was to increase the understanding of metabolic alterations associated with healthy and unhealthy obesity.

METHODS

In this cross-sectional study, men and women (18-70 years) with obesity (body mass index (BMI) ≥ 30 kg/m²) or normal weight (NW) (BMI ≤ 25 kg/m²) were classified with MHO (n = 9), MUO (n = 10) or NW (n = 11) according to weight, lipid profile and glycemic regulation. We characterized individuals by comprehensive metabolic profiling using a commercial available high-throughput proton NMR metabolomics platform. Plasma fatty acid profile, including short chain fatty acids, was measured using gas chromatography.

RESULTS

The concentrations of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) subclasses were overall significantly higher, and high density lipoprotein (HDL) subclasses lower in MUO compared with MHO. VLDL and IDL subclasses were significantly lower and HDL subclasses were higher in NW compared with MHO. The concentration of isoleucine, leucine and valine was significantly higher in MUO compared with MHO, and the concentration phenylalanine was lower in NW subjects compared with MHO. The fatty acid profile in MHO was overall more favorable compared with MUO.

CONCLUSIONS

Comprehensive metabolic profiling supports that MHO subjects have intermediate-stage cardiovascular disease risk marker profile compared with NW and MUO subjects.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01034436, Fatty acid quality and overweight (FO-study).

Association of proinflammatory genes expression with serum interleukin 1β and free fatty acids in metabolically healthy and unhealthy abdominally obese individuals: a case-control study

Background

Proinflammatory genes are highly expressed in several metabolic disorders associated with obesity. But it is not clarified whether gene expression levels and downstream inflammatory markers are related to the metabolic state or the presence of obesity. Hence, the present study aimed to compare Toll-Like Receptor 2 (TLR2), Myeloid Differentiation Factor 88 (MyD88), and NFĸB mRNA expression levels between metabolically healthy abdominally obese (MHAO) and metabolically unhealthy abdominally obese (MUAO) individuals.

Results

We compared mRNA expression levels of the genes as well as serum FFAs and IL-1β in MUAO (n = 36) and MHAO (n = 34) groups. Serum FBS, TG, and HDL-C in addition to systolic and diastolic blood pressure were significantly higher in MUAO than MHAO groups (p < 0.05). The odds of MUAO was significantly decreased with high HDL-C (OR = 0.22, 95%CI: 0.08–0.63) and increased with high FBS (OR = 7.04, 95%CI: 1.42–34.69) and TG (OR = 30.55, 95%CI: 7.48–60.67). There were no significant differences in proinflammatory genes as well as serum FFAs and IL-1β between the two groups. No associations were found between the genes expression and serum markers. However, NFĸB expression was significantly correlated with TLR2 and MyD88 (r = 0.747; p < 0.001). Significant correlations were also noticed between TLR2 and MyD88 expression as well as between serum FFAs and IL-1β in each group (p < 0.001).

Conclusion

Serum concentration of IL-1β, FFAs, and mRNA expression levels of TLR2, MyD88, and NFĸB may be resulted from abdominal obesity and not be related to the presence or absence of metabolic health.

Environmental Signals Influencing Myeloid Cell Metabolism and Function in Diabetes

The environment induces metabolic reprogramming of immune cells via specific signaling pathways. Recent studies have revealed that changes in cell metabolism affect key immune cell functions including cytokine production and migration. In diabetes, these functions are either insufficiently or excessively activated, translating into diabetes-associated complications, including increased susceptibility to infection and accelerated cardiovascular disease. Diabetes alters the abundance of environmental signals, including glucose, insulin, and lipids. Subsequently, changes in environmental signals drive metabolic reprogramming, impair immune cell function, and ultimately contribute to diabetes-associated complications. We review here recent studies on changes in innate immune cell metabolism, especially in myeloid cells, that are driven by environmental signals relevant to diabetes, and discuss therapeutic perspectives of targeting metabolism of immune cells in diabetes.

Toll-like receptor signaling and serum levels of interferon β and lipopolysaccharide binding protein are related to abdominal obesity: a case-control study between metabolically healthy and metabolically unhealthy obese individuals

It is still unclear whether toll-like receptor (TLR) signaling and serum levels of inflammatory markers in metabolically unhealthy abdominally obese (MUAO) are due to their obesity and/or their metabolic state. We hypothesized that abdominal obesity is an important mediator of the association of metabolic state with TLR signaling and serum inflammatory markers. Therefore, in this case-control study, we compared the expression levels of TLR4 and Toll/interleukin-1 receptor domain containing adaptor protein-inducing interferon β (TRIF) and serum concentrations of interferon β and lipoprotein-binding protein (LBP) in metabolically healthy abdominally obese (MHAO) and MUAO individuals. Basal blood samples from 65 abdominally obese subjects with waist circumference (WC) of at least 95 cm were collected to determine serum metabolic parameters, IFNβ, and LBP. Those with 3 or more metabolic alterations were defined as MUAO (n = 34), and those having 2 or less were classified as MHAO (n = 31). Furthermore, messenger RNA (mRNA) was isolated from peripheral blood mononuclear cells. TLR4 and TRIF gene expression assay was performed using quantitative real-time polymerase chain reaction. There were significant differences in serum fasting blood sugar (P = .017), triglyceride (P < .001), cholesterol (P = .002), and low-density lipoprotein cholesterol (P = .034) between the MUAO and MHAO groups, whereas no significant difference was observed in the expression ratio of TLR4 and TRIF mRNA and serum levels of IFNβ and LBP. However, a significant correlation was noticed between mRNA expression levels of TLR4 and TRIF (r = 0.50, P < .001) and serum IFNβ and LBP (r = 0.70, P < .001). It is concluded that the expression levels of TLR4 and TRIF as well as serum IFNβ and LBP are more related to abdominal obesity than to metabolic health.

Association between uncoupling protein 2, adiponectin and resting energy expenditure in obese women with normal and low resting energy expenditure

Obesity is recognized as the most prevalent metabolic disease worldwide. Decreases in energy expenditure may increase risk of obesity. One of the key regulators of energy balance is uncoupling protein2 (UCP2), a transporter protein presents in mitochondrial inner membrane. Moreover, adiponectin is the most abundant adipocytokine, it may play a role in energy metabolism and gene expression of UCP2. The aim of this study was to investigate potential associations between the level of uncoupling protein 2 and adiponectin and their relationship with REE (Resting Energy Expenditure) in obese women with normal and low resting energy expenditure. A total of 49 subjects (women, 25-50 years old), were included in current study, 16 subjects with BMI > 30 and low resting energy expenditure, 17 subjects with BMI > 30 and normal resting energy expenditure and 16 non-obese subjects as a control group. Anthropometric, body composition parameters and resting energy expenditure were measured. Plasma adiponectin, UCP2 protein and total protein in PBMC were determined. Measured resting energy expenditure in obese subjects with low REE was significantly lower than other groups. Plasma adiponectin in the obese subjects with low REE was significantly lower compared to normal weight group. There was a significant relationship between 'UCP2 protein/Total protein' ratio and plasma adiponectin in obese group with low REE and in three groups when we pooled. There was a significant association between REE and plasma adiponectin in three groups when we pooled. There was a significant association between plasma adiponectin and REE. Moreover, there was a significant relationship between UCP2 and REE.

Adipokines at the crossroad between obesity and cardiovascular disease

Obesity, and especially excessive visceral adipose tissue accumulation, is considered as a low-grade inflammatory state that is responsible for adipocyte dysfunction and associated metabolic disorders. Adipose tissue displays endocrine functions by releasing pro- or antiinflammatory bioactive molecules named adipokines. An altered expression of these molecules, provoked by obesity or adipocyte dysregulation, contributes to major metabolic diseases such as insulin resistance and type 2 diabetes mellitus that are important risk factors for cardiovascular disease. However, obesity is also characterised by the expansion of perivascular adipose tissue that acts locally via diffusion of adipokines into the vascular wall. Local inflammation within blood vessels induced by adipokines contributes to the onset of endothelial dysfunction, atherosclerosis and thrombosis, but also to vascular remodelling and hypertension. A fast expansion of obesity is expected in the near future, which will rapidly increase the incidence of these cardiovascular diseases. The focus of this review is to summarise the link between metabolic and cardiovascular disease and discuss current treatment approaches, limitations and future perspectives for more targeted therapies.

Does dietary fat affect inflammatory markers in overweight and obese individuals?-a review of randomized controlled trials from 2010 to 2016

Background

Obesity, a major cause of death and disability, is increasing worldwide. Obesity is characterized by a chronic, low-grade inflammatory state which is suggested to play a critical role in the development of obesity-related diseases like cardiovascular diseases and type 2 diabetes. In fact, in the hours following consumption of a meal, a transient increase in inflammatory markers occurs, a response that is exaggerated in obese subjects. Dietary composition, including content of dietary fatty acids, may affect this inflammatory response both acutely and chronically, and thereby be predictive of progression of disease. The aim of the review was to summarize the literature from 2010 to 2016 regarding the effects of dietary fat intake on levels of inflammatory markers in overweight and obesity in human randomized controlled trials.

Methods and results

We performed a literature search in MEDLINE, EMBASE, and PubMed databases. The literature search included human randomized controlled trials, both postprandial and long-term interventions, from January 2010 to September 2016. In total, 37 articles were included. Interventions with dairy products, vegetable oils, or nuts showed minor effects on inflammatory markers. The most consistent inflammatory-mediating effects were found in intervention with whole diets, which suggests that many components of the diet reduce inflammation synergistically. Furthermore, interventions with weight reduction and different fatty acids did not clearly show beneficial effects on inflammatory markers.

Conclusion

Most interventions showed either no or minor effects of dietary fat intake on inflammatory markers in overweight and obese subjects. To progress our understanding on how diet and dietary components affect our health, mechanistic studies are required. Hence, future studies should include whole diets and characterization of obese phenotypes at a molecular level, including omics data and gut microbiota.

Dyslipidemia: Obese or Not Obese-That Is Not the Question

PURPOSE OF REVIEW

Purpose of review: It is becoming increasingly clear that some obese individuals do not develop dyslipidemia and instead remain healthy, while some normal weight individuals become dyslipidemic and unhealthy.

RECENT FINDINGS

The present review examines the similarities and differences between healthy and unhealthy individuals with and without obesity and discusses putative underlying mechanisms of dyslipidemia. The presence of dyslipidemia and compromised metabolic health in both lean and obese individuals suggests that the obese phenotype per se does not represent a main independent risk factor for the development of dyslipidemia and that dyslipidemia, rather than obesity, may be the driver of metabolic diseases. Notably, adipose tissue dysfunction and ectopic lipid deposition, in particular in the liver, seems a common trait of unhealthy individuals.

Lack of Effects of a Single High-Fat Meal Enriched with Vegetable n-3 or a Combination of Vegetable and Marine n-3 Fatty Acids on Intestinal Peptide Release and Adipokines in Healthy Female Subjects

Peptides released from the small intestine and colon regulate short-term food intake by suppressing appetite and inducing satiety. Intake of marine omega-3 (n-3) fatty acids (FAs) from fish and fish oils is associated with beneficial health effects, whereas the relation between intake of the vegetable n-3 fatty acid α-linolenic acid and diseases is less clear. The aim of the present study was to investigate the postprandial effects of a single high-fat meal enriched with vegetable n-3 or a combination of vegetable and marine n-3 FAs with their different unsaturated fatty acid composition on intestinal peptide release and the adipose tissue. Fourteen healthy lean females consumed three test meals with different fat quality in a fixed order. The test meal consisted of three cakes enriched with coconut fat, linseed oil, and a combination of linseed and cod liver oil. The test days were separated by 2 weeks. Fasting and postprandial blood samples at 3 and 6 h after intake were analyzed. A significant postprandial effect was observed for cholecystokinin, peptide YY, glucose-dependent insulinotropic polypeptide, amylin and insulin, which increased, while leptin decreased postprandially independent of the fat composition in the high-fat meal. In conclusion, in healthy, young, lean females, an intake of a high-fat meal enriched with n-3 FAs from different origin stimulates intestinal peptide release without any difference between the different fat compositions.

New insight into determining indicators of metabolic status in women: Expression of PPARγ and FABP4 in PBMCs

Adiposity and its metabolic disturbances could be regulated by adipocyte-specific peroxisome proliferator-activated receptor gamma and fatty acid-binding protein4. Although these two proteins are mainly expressed in adipose tissues, they can also be expressed in peripheral blood mononuclear cells, which could be useful for predicting body composition and blood parameters. Thus, this cross-sectional study was performed during January 2013-January 2014 with 229 women (age range, 22-52 years) who were classified as obese or nonobese. Serum glucose, insulin, lipids, and body composition were measured in the fasting state. Peripheral blood mononuclear cells were isolated to extract ribonucleic acid (RNA) and to determine gene expression by real time polymerase chain reaction (PCR). All serum parameters and components of body composition were significantly higher in obese than in nonobese women. Gene expression analysis showed that serum levels of glucose and lipids, except high-density lipoprotein (HDL), were higher in the group that expressed high fatty acid-binding protein4. Increased expression of the peroxisome proliferator-activated receptor gamma was associated with a significant reduction of blood sugar and increased HDL and other lipids and visceral fat. Therefore, it seems that the level of expression of these genes in peripheral blood mononuclear cells may indicate metabolic status.

Effects of a healthy Nordic diet on gene expression changes in peripheral blood mononuclear cells in response to an oral glucose tolerance test in subjects with metabolic syndrome: a SYSDIET sub-study

Background

Diet has a great impact on the risk of developing features of metabolic syndrome (MetS), type 2 diabetes mellitus (T2DM), and cardiovascular diseases (CVD). We evaluated whether a long-term healthy Nordic diet (ND) can modify the expression of inflammation and lipid metabolism-related genes in peripheral blood mononuclear cells (PBMCs) during a 2-h oral glucose tolerance test (OGTT) in individuals with MetS.

Methods

A Nordic multicenter randomized dietary study included subjects (n = 213) with MetS, randomized to a ND group or a control diet (CD) group applying an isocaloric study protocol. In this sub-study, we included subjects (n = 89) from three Nordic centers: Kuopio (n = 26), Lund (n = 30), and Oulu (n = 33) with a maximum weight change of ±4 kg, high-sensitivity C-reactive protein concentration ≤10 mg L⁻¹, and baseline body mass index <39 kg m⁻². PBMCs were isolated, and the mRNA gene expression analysis was measured by quantitative real-time polymerase chain reaction (qPCR). We analyzed the mRNA expression changes of 44 genes before and after a 2hOGTT at the beginning and the end of the intervention.

Results

The healthy ND significantly down-regulated the expression of toll-like receptor 4 (TLR4), interleukin 18 (IL18), and thrombospondin receptor (CD36) mRNA transcripts and significantly up-regulated the expression of peroxisome proliferator-activated receptor delta (PPARD) mRNA transcript after the 2hOGTT compared to the CD.

Conclusions

A healthy ND is able to modify the gene expression in PBMCs after a 2hOGTT. However, more studies are needed to clarify the biological and clinical relevance of these findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s12263-016-0521-4) contains supplementary material, which is available to authorized users.

Whole Blood Transcriptomics Is Relevant to Identify Molecular Changes in Response to Genetic Selection for Feed Efficiency and Nutritional Status in the Pig

The molecular mechanisms underlying feed efficiency need to be better understood to improve animal efficiency, a research priority to support a competitive and sustainable livestock production. This study was undertaken to determine whether pig blood transcriptome was affected by differences in feed efficiency and by ingested nutrients. Growing pigs from two lines divergently selected for residual feed intake (RFI) and fed isoproteic and isocaloric diets contrasted in energy source and nutrients were considered. Between 74 and 132 days of age, pigs (n = 12 by diet and by line) received a regular diet rich in cereals and low in fat (LF) or a diet where cereals where partially substituted by lipids and fibers (HF). At the end of the feeding trial, the total number of white blood cells was not affected by the line or by the diet, whereas the red blood cell number was higher (P<0.001) in low RFI than in high RFI pigs. Analysis of the whole blood transcriptome using a porcine microarray reveals a higher number of probes differentially expressed (DE) between RFI lines than between diets (2,154 versus 92 probes DE, P<0.01). This corresponds to 528 overexpressed genes and 477 underexpressed genes in low RFI pigs compared with high RFI pigs, respectively. Overexpressed genes were predominantly associated with translational elongation. Underexpressed genes were mainly involved in the immune response, regulation of inflammatory response, anti-apoptosis process, and cell organization. These findings suggest that selection for RFI has affected the immune status and defense mechanisms of pigs. Genes DE between diets were mainly related to the immune system and lipid metabolism. Altogether, this study demonstrates the usefulness of the blood transcriptome to identify the main biological processes affected by genetic selection and feeding strategies.

Peripheral mononuclear blood cells contribute to the obesity-associated inflammatory state independently of glycemic status: involvement of the novel proinflammatory adipokines chemerin, chitinase-3-like protein 1, lipocalin-2 and osteopontin

Inflammation is a critical contributor to the pathogenesis of metabolic disorders with adipose tissue being crucial in the inflammatory response by releasing multiple adipokines with either pro- or anti-inflammatory activities with potential functions as metabolic regulators. Peripheral blood mononuclear cells (PBMC) have been proposed as representative of the inflammatory status in obesity. The aim of the present study was to evaluate the contribution of PBMC to the obesity-associated chronic inflammation analyzing the expression of novel adipokines. Samples obtained from 69 subjects were used in the study. Real-time PCR determinations were performed to quantify gene expression levels in PBMC of novel adipokines including chemerin, chitinase-3-like protein 1 (YKL-40), lipocalin-2 (LCN-2) and osteopontin (OPN), and their circulating concentrations were also determined by ELISA. We show, for the first time, that PBMC gene expression levels of chemerin (P < 0.0001), chitinase-3-like protein 1 (P = 0.010), lipocalin-2 (P < 0.0001) and osteopontin (P < 0.0001) were strongly upregulated in obesity independently of the glycemic state. Circulating concentrations of these adipokines followed the same trend being significantly higher (P < 0.05) in obese normoglycemic and type 2 diabetic patients compared to lean volunteers and also associated (P < 0.05) with their corresponding mRNA levels in PBMC. These results provide evidence that alterations in inflammation-related adipokines are manifest in PBMC, which might contribute to the low-grade chronic inflammation that characterizes obesity.

Longitudinal weight differences, gene expression and blood biomarkers in BMI-discordant identical twins

Background

BMI discordant monozygotic (MZ) twins allows an examination of the causes and consequences of adiposity in a genetically controlled design. Few studies have examined longitudinal BMI discordance in MZ pairs.

Objectives

To study the development over time of BMI discordance in adolescent and adult MZ twin pairs, and to examine lifestyle, metabolic, inflammatory, and gene expression differences associated with concurrent and long-term BMI discordance in MZ pairs.

Subjects/Methods

BMI data from 2775 MZ twin pairs, collected in eight longitudinal surveys and a biobank project between 1991 and 2011, were analyzed to characterize longitudinal discordance. Lifestyle characteristics were compared within discordant pairs (ΔBMI ≥ 3 kg/m²) and biomarkers (lipids, glucose, insulin, CRP, fibrinogen, IL-6, TNF-α and sIL-6R and liver enzymes AST, ALT and GGT) and gene expression were compared in peripheral blood from discordant pairs who participated in the NTR biobank project.

Results

The prevalence of discordance ranged from 3.2% in 1991 (mean age=17, SD=2.4) to 17.4% (N=202 pairs) in 2009 (mean age=35, SD=15), and was 16.5% (N=174) among pairs participating in the biobank project (mean age=35, SD=12). Of 699 MZ with BMI data from 3-5 time points, 17 pairs (2.4%) were long-term discordant (at all available time points; mean follow-up range=6.4 years). Concurrently discordant pairs showed significant differences in self-ratings of which twin eats most (p=2.3×10⁻¹³), but not in leisure time exercise activity (p=0.28) and smoking (p>0.05). Ten out of 14 biomarkers showed significantly more unfavorable levels in the heavier of twin of the discordant pairs (p-values < 0.001); most of these biomarker differences were largest in longitudinally discordant pairs. No significant gene expression differences were identified, although high ranking genes were enriched for Gene Ontology (GO) terms highlighting metabolic gene regulation and inflammation pathways.

Conclusions

BMI discordance is uncommon in adolescent identical pairs but increases with higher pair-mean of BMI at older ages, although long-term BMI discordance is rare. In discordant pairs, the heavier twin had a more unfavorable blood biomarker profile than the genetically matched leaner twin, in support of causal effects of obesity.

Increased cardiometabolic risk factors and inflammation in adipose tissue in obese subjects classified as metabolically healthy

OBJECTIVE

It has been suggested that individuals with the condition known as metabolically healthy obesity (MHO) may not have the same increased risk for the development of metabolic abnormalities as their non-metabolically healthy counterparts. However, the validity of this concept has recently been challenged, since it may not translate into lower morbidity and mortality. The aim of the current study was to compare the cardiometabolic/inflammatory profile and the prevalence of impaired glucose tolerance (IGT) and type 2 diabetes (T2D) in patients categorized as having MHO or metabolically abnormal obesity (MAO).

RESEARCH DESIGN AND METHODS

We performed a cross-sectional analysis to compare the cardiometabolic/inflammatory profile of 222 MHO and 222 MAO patients (62% women) matched by age, including 255 lean subjects as reference (cohort 1). In a second cohort, we analyzed the adipokine profile and the expression of genes involved in inflammation and extracellular matrix remodeling in visceral adipose tissue (VAT; n = 82) and liver (n = 55).

RESULTS

The cardiometabolic and inflammatory profiles (CRP, fibrinogen, uric acid, leukocyte count, and hepatic enzymes) were similarly increased in MHO and MAO in both cohorts. Moreover, above 30%of patients classified as MHO according to fasting plasma glucose exhibited IGT or T2D [corrected]. The profile of classic (leptin, adiponectin, resistin) as well as novel (serum amyloid A and matrix metallopeptidase 9) adipokines was almost identical in MHO and MAO groups in cohort 2. Expression of genes involved in inflammation and tissue remodeling in VAT and liver showed a similar alteration pattern in MHO and MAO individuals.

CONCLUSIONS

The current study provides evidence for the existence of a comparable adverse cardiometabolic profile in MHO and MAO patients; thus the MHO concept should be applied with caution. A better identification of the obesity phenotypes and a more precise diagnosis are needed for improving the management of obese individuals.

A distinct fatty acid profile underlies the reduced inflammatory state of metabolically healthy obese individuals

BACKGROUND

Obesity is associated with numerous health complications; however, a subgroup of obese individuals (termed the metabolically healthy obese or MHO) appear to have lower risk for complications such as type 2 diabetes and cardiovascular disease. Emerging evidence suggests that MHO individuals have reduced inflammation compared to their metabolically unhealthy obese (MUO) counterparts. As it is recognized that fatty acids (FAs) have a strong relationship with inflammation, the current study aimed to uncover if the reduced inflammation observed in MHO individuals is mirrored by a more favourable FA profile.

METHODS

Fasted serum samples were collected from lean healthy (LH), MHO, and MUO participants (n = 10/group) recruited from the Diabetes Risk Assessment study. A panel of pro- and anti-inflammatory markers were measured by immunoassay. Total serum FA profiling, as well as the FA composition of circulating phospholipids (PL) and triglycerides (TG), was measured by gas chromatography. ANOVA and Mann-Whitney-Wilcoxon tests were used to assess statistical significance between the groups (P<0.05).

RESULTS

MHO and MUO individuals had similar BMI and body fat %; however, lipid parameters in MHO individuals more closely resembled that of LH individuals. MHO individuals had circulating levels of high sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) similar to LH individuals, while levels of platelet derived growth factor-ββ (PDGF-ββ) were intermediate to that of LH and MUO individuals. FA profiling analysis combined with discriminant analysis modelling highlighted a panel of nine FAs (consisting of three saturated, three monounsaturated, and three polyunsaturated FAs) in PL and TG fractions that distinguished the three groups. Specifically, saturated FA (myristic and stearic acids) levels in MHO individuals resembled that of LH individuals.

CONCLUSION

Our results suggest that the reduced inflammatory state of MHO individuals compared to MUO individuals may stem, in part, from a more favourable underlying FA profile.

Identification of early transcriptome-based biomarkers related to lipid metabolism in peripheral blood mononuclear cells of rats nutritionally programmed for improved metabolic health

Moderate maternal calorie restriction during lactation protects rat offspring against obesity development in adulthood, due to an improved ability to handle and store excess dietary fuel. We used this model to identify early transcriptome-based biomarkers of metabolic health using peripheral blood mononuclear cells (PBMCs), an easily accessible surrogate tissue, by focusing on molecular markers of lipid handling. Male and female offspring of control and 20 % calorie-restricted lactating dams (CR) were studied. At weaning, a set of pups was killed, and PBMCs were isolated for whole-genome microarray analysis. The remaining pups were killed at 6 months of age. CR gave lower body weight, food intake and fat accumulation, and improved levels of insulin and leptin throughout life, particularly in females. Microarray analysis of weaned rat PBMCs identified 278 genes significantly differentially expressed between control and CR. Among lipid metabolism-related genes, expression of Cpt1a, Lipe and Star was increased and Fasn, Lrp1 and Rxrb decreased in CR versus control, with changes fully confirmed by qPCR. Among them, Cpt1a, Fasn and Star emerged as particularly interesting. Transcript levels of Cpt1a in PBMCs correlated with their levels in WAT and liver at both ages examined; Fasn expression levels in PBMCs at an early age correlated with their expression levels in WAT; and early changes in Star expression levels in PBMCs correlated with their expression levels in liver and were sustained in adulthood. These findings reveal the possibility of using transcript levels of lipid metabolism-related genes in PBMCs as early biomarkers of metabolic health status.