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

Clusters of adipose tissue dysfunction in adults with type 2 diabetes identify those with worse lipidomic profile despite similar glycaemic control

AIMS

To investigate clusters of adipose tissue dysfunction, that is, with adipose tissue insulin resistance (ADIPO-IR) and large waist circumference (WC), identify a worse lipidomic profile characterised by a high proportion of lipids rich in saturated fatty acids (SFA).

MATERIALS AND METHODS

Hierarchical clustering based on WC and ADIPO-IR (calculated as fasting plasma non-esterified fatty acids times fasting plasma insulin, FFA×INS), was performed in 192 adults with overweight/obesity and type 2 diabetes (T2D) treated with metformin (HbA1c = 7.8%). Free fatty acid composition and lipidomic profile were measured by mass spectrometry (GC-MS and LC-MSQTOF). Indexes of fatty acid desaturation (stearoyl-coA desaturase-1 activity, SCD116 = palmitoleic acid/palmitic acid and SCD118 = oleic acid/stearic acid) and of insulin resistance (HOMA-IR) were also calculated.

RESULTS

Three clusters were identified: CL1 (ADIPO-IR = 4.9 ± 2.4 and WC = 96±7 cm, mean ± SD), CL2 (ADIPO-IR = 6.5 ± 2.5 and WC = 114 ± 7 cm), and CL3 (ADIPO-IR = 15.0 ± 4.7 and WC = 107 ± 8 cm). Insulin concentrations, ADIPO-IR, and HOMA-IR significantly increased from CL1 to CL3 (all p < 0.001), while fasting glucose concentrations, HbA1c, dietary lipids and caloric intake were similar. Moreover, CL3 showed significantly higher concentrations of monounsaturated free fatty acids, oleic and palmitoleic acids, triglycerides (TAG) rich in saturated FA and associated with de novo lipogenesis (i.e., TAG 46-50), higher SCD116, SCD118, ceramide (d18:0/18:0), and phosphatidylcholine aa(36:5) compared with CL1/CL2 (all p < 0.005).

CONCLUSIONS

High ADIPO-IR and large WC identify a worse lipid profile in T2D characterised by complex lipids rich in SFA, likely due to de novo synthesis given higher plasma monounsaturated FFA and increased desaturase activity indexes.

REGISTRATION NUMBER TRIAL

ID NCT00700856 https://clinicaltrials.gov.

Differences in the levels of inflammatory markers between metabolically healthy obese and other obesity phenotypes in adults: A systematic review and meta-analysis

AIMS

The aim of this study was to systematically review and analyze differences in the levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) comparing metabolically healthy but obese (MHO) with metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), and metabolically unhealthy obese (MUO) subjects.

DATA SYNTHESIS

We searched PubMed, Embase, Web of Science, and Scopus for studies that matched the relevant search terms. Differences in inflammatory marker levels between MHO and the other three phenotypes were pooled as standardized mean differences (SMD) or differences of medians (DM) using a random-effects model. We included 91 studies reporting data on 435,007 individuals. The CRP levels were higher in MHO than in MHNO subjects (SMD = 0.63, 95% CI: 0.49, 0.76; DM = 0.83 mg/L, 95% CI: 0.56, 1.11). The CRP levels were higher in MHO than in MUNO subjects (SMD = 0.16, 95% CI: 0.05, 0.28; DM = 0.39 mg/L, 95% CI: 0.09, 0.69). The CRP levels were lower in MHO than in MUO individuals (SMD = -0.43, 95% CI: -0.54, -0.31; DM = -0.82 mg/L, 95% CI: -1.16, -0.48). The IL-6 levels in MHO were higher than in MHNO while lower than in MUO subjects. The TNF-α levels in MHO were higher than in MHNO individuals.

CONCLUSIONS

This review provides evidence that CRP levels in MHO are higher than in MHNO and MUNO subjects but lower than in MUO individuals. Additionally, IL-6 levels in MHO are higher than in MHNO but lower than in MUO subjects, and TNF-α levels in MHO are higher than in MHNO individuals.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO number: CRD42021234948.

Clinical Classification of Obesity and Implications for Metabolic Dysfunction-Associated Fatty Liver Disease and Treatment

Obesity,and metabolic dysfunction-associated fatty liver disease (MAFLD) have reached epidemic proportions globally. Obesity and MAFLD frequently coexist and act synergistically to increase the risk of adverse clinical outcomes (both hepatic and extrahepatic). Type 2 diabetes mellitus (T2DM) is the most important risk factor for rapid progression of steatohepatitis and advanced fibrosis. Conversely, the later stages of MAFLD are associated with an increased risk of T2DM incident. According to the proposed criteria, MAFLD is diagnosed in patients with liver steatosis and in at least one in three: overweight or obese, T2DM, or signs of metabolic dysregulation if they are of normal weight. However, the clinical classification and correlation between obesity and MAFLD is more complex than expected. In addition, treatment for obesity and MAFLD are associated with a reduced risk of T2DM, suggesting that liver-based treatments could reduce the risk of developing T2DM. This review describes the clinical classification of obesity and MAFLD, discusses the clinical features of various types of obesity and MAFLD, emphasizes the role of visceral obesity and insulin resistance (IR) in the development of MAFLD,and summarizes the existing treatments for obesity and MAFLD that reduce the risk of developing T2DM.

Computational Analysis of Plasma Lipidomics from Mice Fed Standard Chow and Ketogenic Diet

Dietary saturated fatty acids (SFAs) are upregulated in the blood circulation following digestion. A variety of circulating lipid species have been implicated in metabolic and inflammatory diseases; however, due to the extreme variability in serum or plasma lipid concentrations found in human studies, established reference ranges are still lacking, in addition to lipid specificity and diagnostic biomarkers. Mass spectrometry is widely used for identification of lipid species in the plasma, and there are many differences in sample extraction methods within the literature. We used ultra-high performance liquid chromatography (UPLC) coupled to a high-resolution hybrid triple quadrupole-time-of-flight (QToF) mass spectrometry (MS) to compare relative peak abundance of specific lipid species within the following lipid classes: free fatty acids (FFAs), triglycerides (TAGs), phosphatidylcholines (PCs), and sphingolipids (SGs), in the plasma of mice fed a standard chow (SC; low in SFAs) or ketogenic diet (KD; high in SFAs) for two weeks. In this protocol, we used Principal Component Analysis (PCA) and R to visualize how individual mice clustered together according to their diet, and we found that KD-fed mice displayed unique blood profiles for many lipid species identified within each lipid class compared to SC-fed mice. We conclude that two weeks of KD feeding is sufficient to significantly alter circulating lipids, with PCs being the most altered lipid class, followed by SGs, TAGs, and FFAs, including palmitic acid (PA) and PA-saturated lipids. This protocol is needed to advance knowledge on the impact that SFA-enriched diets have on concentrations of specific lipids in the blood that are known to be associated with metabolic and inflammatory diseases. Key features • Analysis of relative plasma lipid concentrations from mice on different diets using R. • Lipidomics data collected via ultra-high performance liquid chromatography (UPLC) coupled to a high-resolution hybrid triple quadrupole-time-of-flight (QToF) mass spectrometry (MS). • Allows for a comprehensive comparison of diet-dependent plasma lipid profiles, including a variety of specific lipid species within several different lipid classes. • Accumulation of certain free fatty acids, phosphatidylcholines, triglycerides, and sphingolipids are associated with metabolic and inflammatory diseases, and plasma concentrations may be clinically useful.

Fecal Concentrations of Long-Chain Fatty Acids, Sterols, and Unconjugated Bile Acids in Cats with Chronic Enteropathy

Chronic enteropathy (CE) in cats encompasses food-responsive enteropathy, chronic inflammatory enteropathy (or inflammatory bowel disease), and low-grade intestinal T-cell lymphoma. While alterations in the gut metabolome have been extensively studied in humans and dogs with gastrointestinal disorders, little is known about the specific metabolic profile of cats with CE. As lipids take part in energy storage, inflammation, and cellular structure, investigating the lipid profile in cats with CE is crucial. This study aimed to measure fecal concentrations of various fatty acids, sterols, and bile acids. Fecal samples from 56 cats with CE and 77 healthy control cats were analyzed using gas chromatography-mass spectrometry, targeting 12 fatty acids, 10 sterols, and 5 unconjugated bile acids. Fecal concentrations of nine targeted fatty acids and animal-derived sterols were significantly increased in cats with CE. However, fecal concentrations of plant-derived sterols were significantly decreased in cats with CE. Additionally, an increased percentage of primary bile acids was observed in a subset of cats with CE. These findings suggest the presence of lipid maldigestion, malabsorption, and inflammation in the gastrointestinal tract of cats with CE. Understanding the lipid alterations in cats with CE can provide insights into the disease mechanisms and potential future therapeutic strategies.

A new frontier for fat: dietary palmitic acid induces innate immune memory

Dietary saturated fats have recently been appreciated for their ability to modify innate immune cell function, including monocytes, macrophages, and neutrophils. Many dietary saturated fatty acids (SFAs) embark on a unique pathway through the lymphatics following digestion, and this makes them intriguing candidates for inflammatory regulation during homeostasis and disease. Specifically, palmitic acid (PA) and diets enriched in PA have recently been implicated in driving innate immune memory in mice. PA has been shown to induce long-lasting hyper-inflammatory capacity against secondary microbial stimuli in vitro and in vivo, and PA-enriched diets alter the developmental trajectory of stem cell progenitors in the bone marrow. Perhaps the most relevant finding is the ability of exogenous PA to enhance clearance of fungal and bacterial burdens in mice; however, the same PA treatment enhances endotoxemia severity and mortality. Westernized countries are becoming increasingly dependent on SFA-enriched diets, and a deeper understanding of SFA regulation of innate immune memory is imperative in this pandemic era.

Prevalence and predictors of metabolically healthy obesity in severely obese Asian children

BACKGROUND

Obese individuals who have little or no metabolic syndrome components are proposed to be "metabolically healthy obese (MHO)". This study aim to evaluate the prevalence of MHO and examine the predictors associated with MHO in a multi-ethnic Asian cohort of severely obese children.

METHODS

This study included a cross-sectional cohort of 406 Chinese, Malay and Indian children aged 5-20 years old with BMI for age ≥ 97th percentile. Metabolic syndrome (MS) and metabolic health (MH) definitions based on the presence or absence of metabolic abnormalities (High triglycerides, low HDL cholesterol, elevated blood pressure and high glucose) were used to define MHO in the cohort.

RESULTS

The prevalence of MHO is 63.5% by MS definition and 22.4% by MH definition. Maternal healthy metabolic status (OR: 2.47), age (OR: 0.83, 0.80), paternal obesity (OR: 0.48, 0.53), Malay (OR: 1.97) and Indian ethnicity (OR: 6.38, 3.21) (compared to Chinese ethnicity) are independent predictors for MHO phenotype based on different MHO definitions.

CONCLUSIONS

Adiposity measures are not associated with MHO phenotype, but instead younger age, maternal healthy metabolic status, absence of paternal obesity, Malay and Indian ethnicity are independent predictors for MHO phenotype in a multi-ethnic Asian cohort of severely obese children.

IMPACT

The prevalence of metabolically healthy obese (MHO) in our multi-ethnic Asian cohort of severely obese children is 63.5% and 22.4%, respectively, based on different MHO definitions. Adiposity measures are not associated with the MHO phenotype. There are other factors that contribute to the metabolic phenotype in obese individuals. Younger age, maternal healthy metabolic status, absence of paternal obesity, Malay and Indian ethnicity are independent predictors for MHO phenotype. Parental influence is important in predicting metabolic health in obese individuals.

Enriched dietary saturated fatty acids induce trained immunity via ceramide production that enhances severity of endotoxemia and clearance of infection

Trained immunity is an innate immune memory response that is induced by a primary inflammatory stimulus that sensitizes monocytes and macrophages to a secondary pathogenic challenge, reprogramming the host response to infection and inflammatory disease. Dietary fatty acids can act as inflammatory stimuli, but it is unknown if they can act as the primary stimuli to induce trained immunity. Here we find mice fed a diet enriched exclusively in saturated fatty acids (ketogenic diet; KD) confer a hyper-inflammatory response to systemic lipopolysaccharide (LPS) and increased mortality, independent of diet-induced microbiome and hyperglycemia. We find KD alters the composition of the hematopoietic stem cell compartment and enhances the response of bone marrow macrophages, monocytes, and splenocytes to secondary LPS challenge. Lipidomics identified enhanced free palmitic acid (PA) and PA-associated lipids in KD-fed mice serum. We found pre-treatment with physiologically relevant concentrations of PA induces a hyper-inflammatory response to LPS in macrophages, and this was dependent on the synthesis of ceramide. In vivo, we found systemic PA confers enhanced inflammation and mortality in response to systemic LPS, and this phenotype was not reversible for up to 7 days post-PA-exposure. Conversely, we find PA exposure enhanced clearance of Candida albicans in Rag1-/- mice. Lastly, we show that oleic acid, which depletes intracellular ceramide, reverses PA-induced hyper-inflammation in macrophages and enhanced mortality in response to LPS. These implicate enriched dietary SFAs, and specifically PA, in the induction of long-lived innate immune memory and highlight the plasticity of this innate immune reprogramming by dietary constituents.

Unique Metabolic Profiles Associate with Gestational Diabetes and Ethnicity in Low- and High-Risk Women Living in the UK

BACKGROUND

Gestational diabetes mellitus (GDM) is the most common global pregnancy complication; however, prevalence varies substantially between ethnicities, with South Asians (SAs) experiencing up to 3 times the risk of the disease compared with white Europeans (WEs). Factors driving this discrepancy are unclear, although the metabolome is of great interest as GDM is known to be characterized by metabolic dysregulation.

OBJECTIVES

The primary aim was to characterize and compare the metabolic profiles of GDM in SA and WE women (at <28 wk of gestation) from the Born in Bradford (BIB) prospective birth cohort in the United Kingdom.

METHODS

In total, 146 fasting serum metabolites, from 2,668 pregnant WE and 2,671 pregnant SA women (average BMI 26.2 kg/m2, average age 27.3 y) were analyzed using partial least squares discriminatory analyses to characterize GDM status. Linear associations between metabolite values and post-oral glucose tolerance test measures of dysglycemia (fasting glucose and 2 h postglucose) were also examined.

RESULTS

Seven metabolites associated with GDM status in both ethnicities (variable importance in projection ≥1), whereas 6 additional metabolites associated with GDM only in WE women. Unique metabolic profiles were observed in healthy-weight women who later developed GDM, with distinct metabolite patterns identified by ethnicity and BMI status. Of the metabolite values analyzed in relation to dysglycemia, lactate, histidine, apolipoprotein A1, HDL cholesterol, and HDL2 cholesterol associated with decreased glucose concentration, whereas DHA and the diameter of very low-density lipoprotein particles (nm) associated with increased glucose concertation in WE women, and in SAs, albumin alone associated with decreased glucose concentration.

CONCLUSIONS

This study shows that the metabolic risk profile for GDM differs between WE and SA women enrolled in BiB in the United Kingdom. This suggests that etiology of the disease differs between ethnic groups and that ethnic-appropriate prevention strategies may be beneficial.

The Harm of Metabolically Healthy Obese and the Effect of Exercise on Their Health Promotion

Obesity and obesity-related diseases [type 2 diabetes, cardiovascular disease (CVD), and cancer] are becoming more common, which is a major public health concern. Metabolically healthy obesity (MHO) has become a type of obesity, accounting for a large proportion of obese people. MHO is still harmful to health. It was discovered that MHO screening criteria could not well reflect health hazards, whereas visceral fat, adiponectin pathway, oxidative stress, chronic inflammation, and histological indicators at the microlevel could clearly distinguish MHO from health control, and the biological pathways involved in these micro indicators were related to MHO pathogenesis. This review reveals that MHO’s micro metabolic abnormality is the initial cause of the increase of disease risk in the future. Exploring the biological pathway of MHO is important in order to develop an effective mechanism-based preventive and treatment intervention strategy. Exercise can correct the abnormal micro metabolic pathway of MHO, regulate metabolic homeostasis, and enhance metabolic flexibility. It is a supplementary or possible alternative to the traditional healthcare prevention/treatment strategy as well as an important strategy for reducing MHO-related health hazards.

Myristic Acid Supplementation Aggravates High Fat Diet-Induced Adipose Inflammation and Systemic Insulin Resistance in Mice

Saturated fatty acids (SFAs) are considered to be detrimental to human health. One of the SFAs, myristic acid (MA), is known to exert a hypercholesterolemic effect in mice as well as humans. However, its effects on altering adipose tissue (AT) inflammation and systemic insulin resistance (IR) in obesity are still unclear. Here, we sought to determine the effects of a high fat (HF) diet supplemented with MA on obesity-associated metabolic disorders in mice. Wild-type C57BL/6 mice were fed a HF diet in the presence or absence of 3% MA for 12 weeks. Plasma lipids, plasma adipokines, AT inflammation, systemic IR, glucose homeostasis, and hepatic steatosis were assessed. The body weight and visceral adipose tissue (VAT) mass were significantly higher in mice receiving the HF+MA diet compared to HF diet-fed controls. Plasma total cholesterol levels were marginally increased in HF+MA-fed mice compared to controls. Fasting blood glucose was comparable between HF and HF+MA-fed mice. Interestingly, the plasma insulin and HOMA-IR index, a measure of insulin resistance, were significantly higher in HF+MA-fed mice compared to HF controls. Macrophage and inflammatory markers were significantly elevated in the AT and AT-derived stromal vascular cells upon MA feeding. Moreover, the level of circulating resistin, an adipokine promoting insulin resistance, was significantly higher in HF+MA-fed mice compared with HF controls. The insulin tolerance test revealed that the IR was higher in mice receiving the MA supplementation compared to HF controls. Moreover, the glucose tolerance test showed impairment in systemic glucose homeostasis in MA-fed mice. Analyses of liver samples showed a trend towards an increase in liver TG upon MA feeding. However, markers of oxidative stress and inflammation were reduced in the liver of mice fed an MA diet compared to controls. Taken together, our data suggest that chronic administration of MA in diet exacerbates obesity-associated insulin resistance and this effect is mediated in part, via increased AT inflammation and increased secretion of resistin.

Prevalence and clinical characteristics of metabolically healthy obese versus metabolically unhealthy obese school children

INTRODUCTION

Children with obesity in the absence of traditional cardiometabolic risk factors (CRF) have been described as metabolically healthy obese (MHO). Children with MHO phenotype has a favorable metabolic profile with normal glucose metabolism, lipids, and blood pressure compared to children with metabolically unhealthy obese (MUO) phenotype. This study aimed to compare several parameters related to obesity between these two groups and to examine the predictors associated with the MHO phenotype.

METHODS

This study included a cross-sectional baseline data of 193 children with obesity (BMI z-score > +2 SD) aged 8-16 years enrolled in MyBFF@school program, a school-based intervention study conducted between January and December 2014. Metabolic status was defined based on the 2018 consensus-based criteria with MHO children had no CRF (HDL-cholesterol > 1.03 mmol/L, triglycerides ≤ 1.7 mmol/L, systolic and diastolic blood pressure ≤ 90^th percentile, and fasting plasma glucose ≤ 5.6 mmol/L). Those that did not meet one or more of the above criteria were classified as children with MUO phenotype.

RESULTS

The prevalence of MHO was 30.1% (95% CI 23.7 - 37.1) among schoolchildren with obesity and more common in younger and prepubertal children. Compared to MUO, children with MHO phenotype had significantly lower BMI, lower waist circumference, lower uric acid, higher adiponectin, and higher apolipoprotein A-1 levels (p < 0.01). Multivariate logistic regression showed that adiponectin (OR: 1.33, 95% CI 1.05 - 1.68) and apolipoprotein A-1 (OR: 1.02, 95% CI 1.01 - 1.03) were independent predictors for MHO phenotype in this population.

CONCLUSIONS

MHO phenotype was more common in younger and prepubertal children with obesity. Higher serum levels of adiponectin and apolipoprotein A-1 increased the possibility of schoolchildren with obesity to be classified into MHO phenotype.

Obesity-Related Metabolic Dysfunction in Dairy Cows and Horses: Comparison to Human Metabolic Syndrome

Obesity has become a serious health problem with frequent occurrence both in human and animal populations. It is estimated that it may affect over 85% of the human population and 70–80% of horses and cows by 2030. Fat cow syndrome (FCS) is a combination of metabolic, digestive, infectious, and reproductive disorders that affects obese periparturient dairy cows, and occurs most frequently in loose-housing systems, where periparturient and dry cows are fed and managed in one group disregarding the lactation stages. Equine metabolic syndrome (EMS) was named after human metabolic syndrome (MetS) and has insulin dysregulation as a central and consistent feature. It is often associated with obesity, although EMS may occur in a lean phenotype as well. Other inconsistent features of EMS are cardiovascular changes and adipose dysregulation. Laminitis is the main clinical consequence of EMS. MetS holds a 30-years old lead in research and represents a clustering of risk factors that comprise abdominal obesity, dyslipidemia, hypertension, and hyperglycemia (impaired fasting glucose or type 2 diabetes mellitus—T2DM), which are associated with doubled atherosclerotic cardiovascular disease risk, and a 5-fold increased risk for T2DM. The main aim of this review is to provide critical information for better understanding of the underlying mechanisms of obesity-related metabolic dysfunction in animals, especially in cows and horses, in comparison with MetS. Human medicine studies can offer suitable candidate mechanisms to fill the existing gap in the literature, which might be indispensable for owners to tackle FCS, EMS, and their consequences.

Dysregulation of endocannabinoid concentrations in human subcutaneous adipose tissue in obesity and modulation by omega-3 polyunsaturated fatty acids

Obesity is believed to be associated with a dysregulated endocannabinoid system which may reflect enhanced inflammation. However, reports of this in human white adipose tissue (WAT) are limited and inconclusive. Marine long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFAs) have anti-inflammatory actions and therefore may improve obesity-associated adipose tissue inflammation. Therefore, fatty acid (FA) concentrations, endocannabinoid concentrations, and gene expression were assessed in subcutaneous WAT (scWAT) biopsies from healthy normal weight individuals (BMI 18.5-25 kg/m2) and individuals living with metabolically healthy obesity (BMI 30-40 kg/m2) prior to and following a 12-week intervention with 3 g fish oil/day (1.1 g eicosapentaenoic acid (EPA) + 0.8 g DHA) or 3 g corn oil/day (placebo). WAT from individuals living with metabolically healthy obesity had higher n-6 PUFAs and EPA, higher concentrations of two endocannabinoids (anandamide (AEA) and eicosapentaenoyl ethanolamide (EPEA)), higher expression of phospholipase A2 Group IID (PLA2G2D) and phospholipase A2 Group IVA (PLA2G4A), and lower expression of CNR1. In response to fish oil intervention, WAT EPA increased to a similar extent in both BMI groups, and WAT DHA increased by a greater extent in normal weight individuals. WAT EPEA and docosahexaenoyl ethanolamide (DHEA) increased in normal weight individuals only and WAT 2-arachidonyl glycerol (2-AG) decreased in individuals living with metabolically healthy obesity only. Altered WAT fatty acid, endocannabinoid, and gene expression profiles in metabolically healthy obesity at baseline may be linked. WAT incorporates n-3 PUFAs when their intake is increased which affects the endocannabinoid system; however, effects appear greater in normal weight individuals than in those living with metabolically healthy obesity.

Molecular Aspects of Lifestyle and Environmental Effects in Patients With Diabetes: JACC Focus Seminar

Diabetes is characterized as an integrated condition of dysregulated metabolism across multiple tissues, with well-established consequences on the cardiovascular system. Recent advances in precision phenotyping in biofluids and tissues in large human observational and interventional studies have afforded a unique opportunity to translate seminal findings in models and cellular systems to patients at risk for diabetes and its complications. Specifically, techniques to assay metabolites, proteins, and transcripts, alongside more recent assessment of the gut microbiome, underscore the complexity of diabetes in patients, suggesting avenues for precision phenotyping of risk, response to intervention, and potentially novel therapies. In addition, the influence of external factors and inputs (eg, activity, diet, medical therapies) on each domain of molecular characterization has gained prominence toward better understanding their role in prevention. Here, the authors provide a broad overview of the role of several of these molecular domains in human translational investigation in diabetes.

Age-related compositional changes and correlations of gut microbiome, serum metabolome, and immune factor in rats

Aging is a complex physiological process associated with degenerative disorder of metabolism and immune function, which contributes to the occurrence of senile diseases. The gut microbiota affects systemic inflammation in aging processes probably through metabolism, but their relationship is still unclear. In this study, 16S-rRNA-sequencing technology, gas chromatography-time-of-flight mass spectrometry (GC-TOFMS)-based metabolic profiling, and immune factor analysis combined with advanced differential and association analysis were employed to investigate the correlation between the microbiome, metabolome, and immune factors in male Wistar rats across lifespan. Our findings showed significant changes in the ileum microbiome and serum metabolome compositions across aging process. A two-level strategy was applied to demonstrate that key metabolites associated with age such as 4-hydroxyproline, proline, and lysine were clustered together and positively correlated with beneficial microbes including Bifidobacterium, Lactobacillus, and Akkermansia. Function analysis explored association between serum metabolite class and specific gut bacteria's metabolism pathways. Further correlation analysis on all the alteration patterns provided an interaction network of main immune factors such as IL-10, IgA, IgM, and IgG with key gut bacteria and serum metabolites. This study offers new insights into the relationship between immune factors, serum metabolome, and the gut microbiome.

Obesity subtypes, related biomarkers & heterogeneity

Obesity is a serious medical condition worldwide, which needs new approaches and recognized international consensus in treating diseases leading to morbidity. The aim of this review was to examine heterogeneous links among the various phenotypes of obesity in adults. Proteins and associated genes in each group were analysed to differentiate between biomarkers. A variety of terms for classification and characterization within this pathology are currently in use; however, there is no clear consensus in terminology. The most significant groups reviewed include metabolically healthy obese, metabolically abnormal obese, metabolically abnormal, normal weight and sarcopenic obese. These phenotypes do not define particular genotypes or epigenetic gene regulation, or proteins related to inflammation. There are many other genes linked to obesity, though the value of screening all of those for diagnosis has low predictive results, as there are no significant biomarkers. It is important to establish a consensus in the terminology used and the characteristics attributed to obesity subtypes. The identification of specific molecular biomarkers is also required for better diagnosis in subtypes of obesity.

Metabolomic Signature Between Metabolically Healthy Overweight/Obese and Metabolically Unhealthy Overweight/Obese: A Systematic Review

The clinical manifestations of overweight/obesity are heterogeneous and complex. In contrast to metabolically unhealthy overweight/obese (MUO), a particular sub-group of obese patients who are considered as metabolically healthy overweight/obese (MHO), display favorable metabolic profiles characterized by high levels of insulin sensitivity, normal blood pressure, as well as favorable lipid, inflammation, hormone, liver enzyme, and immune profiles. While only a few available studies focused on the metabolic files underlying the obese phenotypes, the current review aimed to perform a systematic review of available studies focusing on describing the metabolomic signature between MUO and MHO. We did the systematic search for literature on MEDLINE (PubMed), the Cochrane Library, EMBASE, and searched for the references of relevant manuscripts from inception to 29 May 2020. After critical selection, 20 studies were eligible for this systematic review and evaluated by using QUADOMICS for quality assessment. Eventually, 12 of 20 studies were classified as "high quality". Branched-chain amino acids (isoleucine, leucine, and valine), aromatic amino acids (phenylalanine and tyrosine), lipids (palmitic acid, palmitoleic acid, oleic acid, eicosapentaenoic acid, and docosahexaenoic acid), and acylcarnitines (propionyl carnitine) levels might be elevated in MUO. The current results suggested that MHO showed a favorable trend in the overall metabolic signature. More longitudinal studies are needed to elaborate deeply on the metabolic pathway and the relationship between metabolic patterns and the occurrence of the disease.

Healthy Obese Subjects Differ in Chronotype, Sleep Habits, and Adipose Tissue Fatty Acid Composition from Their Non-Healthy Counterparts

Obesity is not the same in all individuals and two different phenotypes have been described: metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). The aim of this study was to identify factors that explain metabolic health status in a rigorously matched Spanish population. Subcutaneous and visceral fat, adipocyte size and fatty acid composition, cardiometabolic markers in serum, and lifestyle habits were assessed. Higher physical activity in the mornings (Odds Ratio (95% Confidence Interval) (OR (95% CI) = 1.54 (1.09–2.18), p = 0.01)), earlier bedtimes (8:30–10:30 pm) (OR = 2.11 (1.02–4.36), p = 0.04), a complete breakfast (OR = 1.59 (1.07–2.36), p = 0.02), and a greater number of meals per day (4.10 ± 0.05 vs. 3.93 ± 0.05, p < 0.01), were associated with the MHO phenotype. Concentrations of 20:5 n-3 eicosapentaenoic acid (0.26 ± 0.46 vs. 0.10% ± 0.11%, p = 0.04) and 18:3 n-6 gamma-linolenic acid (0.37 ± 0.24 vs. 0.23% ± 0.22%, p = 0.04) in subcutaneous adipocytes were higher and omental adipocyte size (187 094 ± 224 059 µm³ vs. 490 953 ± 229 049 µm³, p = 0.02) was lower in MHO subjects than in those with MUO. Visceral fat area differed between MHO and MUO subjects (135 ± 60 cm² vs. 178 ± 85 cm², p = 0.04, respectively). The study highlights specific lifestyle habits that could form part of obesity therapies, not only involving healthier eating habits but also earlier sleeping and exercise patterns.

Sample Preparation Methods for Lipidomics Approaches Used in Studies of Obesity

Obesity is associated with alterations in the composition and amounts of lipids. Lipids have over 1.7 million representatives. Most lipid groups differ in composition, properties and chemical structure. These small molecules control various metabolic pathways, determine the metabolism of other compounds and are substrates for the syntheses of different derivatives. Recently, lipidomics has become an important branch of medical/clinical sciences similar to proteomics and genomics. Due to the much higher lipid accumulation in obese patients and many alterations in the compositions of various groups of lipids, the methods used for sample preparations for lipidomic studies of samples from obese subjects sometimes have to be modified. Appropriate sample preparation methods allow for the identification of a wide range of analytes by advanced analytical methods, including mass spectrometry. This is especially the case in studies with obese subjects, as the amounts of some lipids are much higher, others are present in trace amounts, and obese subjects have some specific alterations of the lipid profile. As a result, it is best to use a method previously tested on samples from obese subjects. However, most of these methods can be also used in healthy, nonobese subjects or patients with other dyslipidemias. This review is an overview of sample preparation methods for analysis as one of the major critical steps in the overall analytical procedure.

Comparison of dietary and plasma phospholipid fatty acids between normal weight and overweight black South Africans according to metabolic health: The PURE study

BACKGROUND

Information regarding circulating fatty acids (FA) in association with metabolic health in black Africans is scarce, while the usefulness of circulating FAs as biomarkers of dietary fat intake and predictors for medical conditions is increasing.

OBJECTIVE

We compared eleven dietary and the levels of 26 plasma phospholipid FAs in metabolically healthy and unhealthy phenotypes in black South African adults.

METHODS

Adults from the South African arm of the Prospective Urban and Rural Epidemiology study baseline (n = 711) were categorised into four groups, namely normal weight without metabolic syndrome (MetS) (MHNW), normal weight with MetS (MUNW), metabolically healthy overweight/obese (MHO) and metabolically unhealthy overweight/obese (MUO). Dietary and plasma phospholipid FAs were measured by a quantitative food frequency questionnaire and gas chromatography-tandem mass spectrometry, respectively. We compared dietary FAs, plasma phospholipid FAs, and estimated desaturase activity between the metabolic status groups using ANCOVA adjusted for age and energy intake.

RESULTS

MetS was diagnosed in 35% of the participants. After adjustment for age and total energy intake, in comparison to the MHNW reference group, saturated dietary FAs (C14:0 to C18:0) and alpha-linolenic acid intakes were higher in both overweight/obese groups (MHO and MUO), while linoleic acid intakes were higher in the MUO group only. Plasma levels of most saturated FAs (C18:0 to C22:0) and PUFAs were higher, whereas selected MUFAs, palmitic acid, and estimated desaturase activities were lower in the overweight/obese groups.

CONCLUSIONS

The overweight groups generally had higher fat intakes than normal-weight groups, but lower plasma levels of palmitic, palmitoleic, oleic, cis-vaccenic and estimated desaturase activities. Therefore, in this population, lower plasma levels of palmitic, palmitoleic, oleic, and cis-vaccenic acids and decreased estimated desaturase activities may be biomarkers of abnormal metabolic health in overweight/obese study participants.

Metabolomic Profiles of Overweight/Obesity Phenotypes During Adolescence: A Cross-Sectional Study in Project Viva

OBJECTIVE

The purpose of this article is to characterize metabolomic profiles of four overweight/obesity (OWOB) and metabolic risk (MetRisk) phenotypes among 524 adolescents aged approximately 13 years.

METHODS

A four-level phenotype variable (non-OWOB and low MetRisk, non-OWOB and high MetRisk, OWOB and low MetRisk, and OWOB and high MetRisk) was created using BMI percentile to define OWOB, and high versus low MetRisk was derived as the fourth versus first to third quartiles of a z score calculated as the average of five externally standardized z scores for waist circumference, homeostatic model assessment of insulin resistance, high-density lipoprotein, triglycerides, and systolic blood pressure. Then associations of nine metabolite patterns derived from principal components analysis with phenotype after accounting for age, sex, race, and pubertal status were evaluated.

RESULTS

Five metabolite patterns differed with respect to phenotype: factor 1 consisted of long-chain fatty acids and was lower among non-OWOB and high MetRisk (-0.90 [95% CI: -1.39 to -0.42]) versus non-OWOB and low MetRisk (referent); factors 5 (branched-chain amino acids), 8 (diacylglycerols), and 9 (steroid hormones) were highest among OWOB and high MetRisk; and factor 7 (long-chain acylcarnitines) was higher among non-OWOB and high MetRisk (0.47 [95% CI: 0.04 to 0.91]) and lower among OWOB and low MetRisk (-0.36 [95% CI: -0.68 to -0.04]).

CONCLUSIONS

Long-chain fatty acids, branched-chain amino acids, acylcarnitines, diacylglycerols, and steroid hormones differed by weight status and metabolic phenotype.

Metabolomic Profiles Associated with BMI, Waist Circumference, and Diabetes and Inflammation Biomarkers in Women

OBJECTIVE

This study was undertaken to identify metabolites associated with BMI and waist circumference (WC) in women and to determine whether these metabolites are associated with biomarkers of metabolic health.

METHODS

Untargeted metabolomic analysis was done on serum from 1,534 women. Metabolites associated with BMI and WC were identified using linear regression with a Bonferroni-corrected P value. Clustered blocks of these metabolites were then defined whose association with the anthropometric measures could be represented by a single metabolite. The association of these representative metabolites with biomarkers for diabetes and inflammation was then determined.

RESULTS

About one-third of 781 metabolites included in the analyses were associated with BMI and/or WC. Associations were found for some novel metabolites, including several sphingolipids, nucleotides, and modified fatty acids. Among metabolites most strongly inversely associated with BMI, the choline-containing plasmalogen (O-16:0/18:1) (β = -0.30, P = 6.62 × 10^-32 ) was also inversely associated with c-peptide and positively associated with adiponectin. Adjustment for BMI attenuated the metabolite-biomarker associations more for hemoglobin A1c (> 100%) and c-peptide (58.8% to > 100%) than for C-reactive protein (10.5%-40.0%) and adiponectin (7.0%-30.4%).

CONCLUSIONS

These results add to the list of metabolites associated with adiposity and indicate that some may influence processes that contribute to the development of obesity-related diseases.

From Table to Stable: A Comparative Review of Selected Aspects of Human and Equine Metabolic Syndrome

Obesity data in people and companion animals are depicting a future of increasing morbidity, cost for society, and significant health and welfare concerns. Between 25 and 50% of cats, dogs, and horses in developed countries are overweight or obese, which mirrors the situation in humans. Equine metabolic syndrome (EMS) was named after human metabolic syndrome (MetS), which has about 30 years of lead in research efforts. Even though the complications of the two syndromes seem to grossly differ (cardiac vs. laminitis risk), a number of similar disease mechanisms are worthy of investigation. Since the first EMS consensus statement by the American College of Veterinary Internal Medicine in 2010, numerous studies have confirmed the link between insulin dysregulation and laminitis, even though the mechanisms are not fully understood. After the discovery of the role of adipokines in MetS, evidence about inflammatory mechanisms related to adiposity in rodent models, companion animals, horses, and humans is constantly increasing. Oxidative and dicarbonyl stress have been correlated with insulin dysregulation, obesity, and recently with laminitis. Vascular actions of insulin through nitric oxide, endothelin-1, and other mechanisms are being studied in horses and can provide a better understanding of laminitis pathophysiology. More research is needed on neuropathic mechanisms in insulin-dysregulated horses, which could be important in the pathogenesis of laminitis and laminitic pain. Human literature can provide viable material for novel studies in areas that have received limited attention, in addition to being valuable information for clients about the consequences of unhealthy management of their horses.

Impact of Intensive Lifestyle Modification on Levels of Adipokines and Inflammatory Biomarkers in Metabolically Healthy Obese Women

Background

For the metabolically healthy obese (MHO) subjects, it is unclear whether weight loss provides cardiometabolic benefits. Our objective was to evaluate whether changes in adipokine and inflammatory biomarker levels were related to lifestyle modification (with Mediterranean diet and physical exercise program).

Methods

115 women (35-55 years) with BMI of 30-40 kg/m² and ≤1 metabolic syndrome criteria were included. After a 2-year intervention, participants were classified by percent weight loss: Group 1, <5%; Group 2, ≥5%-<10%; and Group 3, ≥10%. Anthropometric data, inflammatory biomarker (IL-6, TNFa, and hsCRP) and adipokine levels (adiponectin and resistin), and lifestyle program adherence at baseline and 2 years were analyzed.

Results

The final sample comprised 67 women. 23 (38.3%) lost <5%, 22 (36.7%) lost ≥5%-<10%, and 22 (36.7%) lost ≥10% of baseline weight. After 2 years, in Group 1, adiponectin, hsCRP, IL-6, and TNFa decreased (-1.2 ng/ml, p = 0.003; -2.1 mg/l, p = 0.003; -2.4 pg/ml, p < 0.001; and -2.4 pg/ml, p = 0.001, respectively) and resistin increased (+2.4 ng/ml, p < 0.001). In Group 2, hsCRP and IL-6 decreased (-2.0 mg/l, p = 0.009 and -2.6 pg/ml, p = 0.001) but TNFa increased (+0.2 pg/ml, p = 0.02). In Group 3, resistin increased (+3.5 ng/ml, p < 0.001) but hsCRP, IL-6, and TNFa decreased (-2.0 mg/l, p = 0.009; -2.5 pg/ml, p < 0.001; and -4.1 pg/ml, p < 0.001). Adiponectin, hsCRP, and physical exercise correlated significantly to subjects' dietary adherence.

Conclusion

Weight loss reduces inflammatory biomarkers in the MHO but induces a deterioration in the adipokine profile, which does not improve with diet and exercise intervention. These findings allow us to clarify mechanisms behind inflammation and metabolic disorder genesis so as to prevent development of obesity-associated comorbidities.

Current Progress of Lipid Analysis in Metabolic Diseases by Mass Spectrometry Methods

BACKGROUND

Obesity, insulin resistance, diabetes, and metabolic syndrome are associated with lipid alterations, and they affect the risk of long-term cardiovascular disease. A reliable analytical instrument to detect changes in the composition or structures of lipids and the tools allowing to connect changes in a specific group of lipids with a specific disease and its progress, is constantly lacking. Lipidomics is a new field of medicine based on the research and identification of lipids and lipid metabolites present in human organism. The primary aim of lipidomics is to search for new biomarkers of different diseases, mainly civilization diseases.

OBJECTIVE

We aimed to review studies reporting the application of mass spectrometry for lipid analysis in metabolic diseases.

METHOD

Following an extensive search of peer-reviewed articles on the mass spectrometry analysis of lipids the literature has been discussed in this review article.

RESULTS

The lipid group contains around 1.7 million species; they are totally different, in terms of the length of aliphatic chain, amount of rings, additional functional groups. Some of them are so complex that their complex analyses are a challenge for analysts. Their qualitative and quantitative analysis of is based mainly on mass spectrometry.

CONCLUSION

Mass spectrometry techniques are excellent tools for lipid profiling in complex biological samples and the combination with multivariate statistical analysis enables the identification of potential diagnostic biomarkers.

Fatty Acids Composition of Blood Cell Membranes and Peripheral Inflammation in the PREDIMED Study: A Cross-Sectional Analysis

There is limited evidence from epidemiological studies for the inflammatory or anti-inflammatory properties of fatty acids in blood cell membranes. Therefore, this study examined associations between baseline (n = 282) and 1-year (n = 143) changes in the levels of fatty acids in blood cell membranes with circulating inflammatory markers in older adults at high cardiovascular risk. The data for this cross-sectional analysis was obtained from a case-control study within the PREDIMED study. Linear regression with elastic net penalty was applied to test associations between measured fatty acids and inflammatory markers. Several fatty acids were associated with interferon-γ (IFNγ) and interleukins (ILs) IL-6, IL-8, and IL-10 at baseline and additionally also with IL-1b at 1 year. Omega-6 fatty acids were consistently positively associated with pro-inflammatory IL-6 and IL-8 at baseline. Omega-3 fatty acids including C20:5n3 and C18:3n3 were negatively associated with IFN-γ at 1 year. It is interesting to note that the cis and trans forms of C16:1n7 at 1 year were oppositely associated with the inflammatory markers. C16:1n7trans was negatively associated with IFN-γ, IL-6, IL-8, IL-10, and IL-1b, whereas C16:1n7cis was positively associated with IL-1b. This study adds to the growing body of evidence suggesting potential differences in inflammatory or anti-inflammatory properties of fatty acids in blood cell membranes.

Inflammatory signatures distinguish metabolic health in African American women with obesity

Obesity-driven Type 2 diabetes (T2D) is a systemic inflammatory condition associated with cardiovascular disease. However, plasma cytokines and tissue inflammation that discriminate T2D risk in African American women with obese phenotypes are not well understood. We analyzed 64 circulating cytokines and chemokines in plasma of 120 African American women enrolled in the Black Women’s Health Study. We used regression analysis to identify cytokines and chemokines associated with obesity, co-morbid T2D and hypertension, and compared results to obese women without these co-morbidities, as well as to lean women without the co-morbidities. We then used hierarchical clustering to generate inflammation signatures by combining the effects of identified cytokines and chemokines and summarized the signatures using an inflammation score. The analyses revealed six distinct signatures of sixteen cytokines/chemokines (P = 0.05) that differed significantly by prevalence of T2D (P = 0.004), obesity (P = 0.0231) and overall inflammation score (P < E-12). Signatures were validated in two independent cohorts of African American women with obesity: thirty nine subjects with no metabolic complications or with T2D and hypertension; and thirteen breast reduction surgical patients. The signatures in the validation cohorts closely resembled the distributions in the discovery cohort. We find that blood-based cytokine profiles usefully associate inflammation with T2D risks in vulnerable subjects, and should be combined with metabolism and obesity counselling for personalized risk assessment.

Food withdrawal alters the gut microbiota and metabolome in mice

Food withdrawal as a health-enhancing measure has beneficial effects on aging, disease prevention, and treatment. However, the cellular and molecular mechanisms involving gut microbial changes and metabolic consequences resulting from food withdrawal have yet to be elucidated. In this study, we subjected lean and obese mice to a dietary intervention that consisted of a 4-d complete food withdrawal and an 8-d 50% food withdrawal, and we studied changes in cecal microbiome and host serum metabolome. The abundance of potentially pathogenic Proteobacteria was decreased and Akkermansia muciniphila was elevated by food withdrawal in mice fed a high-fat diet (HFD). Meanwhile, food withdrawal decreased the abundance of metabolites in branched chain amino acid, lipid, and free fatty acid metabolisms in host serum, more so in HFD mice than in normal mice. Microbial predicted function also showed that food withdrawal decreased the abundance of microbes associated with predicted diseases in the HFD group but not in the normal chow group. Correlation between the microbiome data and metabolomics data revealed a strong association between gut microbial and host metabolic changes in response to food withdrawal. In summary, our results showed that food withdrawal was safer and more metabolically beneficial to HFD-induced obese mice than to normal lean mice, and the beneficial effects were primarily derived from the changes in gut microbiota, which were closely associated with the host metabolome.-Zheng, X., Zhou, K., Zhang, Y., Han, X., Zhao, A., Liu, J., Qu, C., Ge, K., Huang, F., Hernandez, B., Yu, H., Panee, J., Chen, T., Jia, W., Jia, W. Food withdrawal alters the gut microbiota and metabolome in mice.

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.

Neither linoleic acid nor arachidonic acid promote white adipose tissue inflammation in Fads2-/- mice fed low fat diets

Dietary n-6 polyunsaturated fatty acids (PUFA) are widely perceived to promote inflammation and contribute to the development of chronic diseases. This dogma has been recently questioned due to evidence that n-6 PUFA, specifically linoleic acid (LA, 18:2n-6) and arachidonic acid (AA, 20:4n-6), do not appear to activate inflammatory signalling pathways when consumed in moderate amounts. However, delineating the independent roles of different dietary n-6 PUFA in vivo is challenging because LA is continuously converted into AA in a pathway regulated by the fatty acid desaturase 2 (Fads2) gene. The objective of this study was to investigate the independent roles of LA and AA on white adipose tissue (WAT) inflammatory signalling pathways using Fads2-/- mice. We hypothesized that dietary LA would not induce WAT inflammation, unless it was endogenously converted into AA. Male C57BL/6 wild-type (WT) and Fads2-/- mice were fed low-fat isocaloric diets containing either 7% corn oil w/w (CD, containing ~42% LA) or 7% ARASCO oil w/w (AD, containing ~27% AA) for 9 weeks. WAT inflammatory gene expression, protein levels, as well as phospholipid (PL) and triacylglycerol (TAG) fatty acid composition, were analyzed by RT-qPCR, western blots, and gas chromatography, respectively. Fads2-/- mice fed CD had high LA, but little-to-no GLA (18:3n-6), DGLA (20:3n-6), and AA in PLs and TAGs compared to their WT counterparts. In comparison, Fads2-/- and WT mice fed AD showed minimal differences in n-6 PUFA content in serum and WAT, despite having significantly more AA than CD-fed mice. No differences in gene expression for common inflammatory adipokines (e.g. Mcp-1, Ccl5, Tnfα) or key regulators of eicosanoid production (e.g. Cox-2, Alox-12, Alox-15) were detected in WAT between any of the diet and genotype groups. Furthermore, no differences in MCP-1, and total or phosphorylated STAT3 and p38 inflammatory proteins, were observed. Collectively, these results demonstrate that neither LA nor AA promote WAT inflammation when consumed as part of a low-fat diet. Therefore, the existing dogma surrounding n-6 PUFA and inflammation needs to be reconsidered.

Alterations in fatty acid metabolism in response to obesity surgery combined with dietary counseling

Background:

The effects of obesity surgery on serum and adipose tissue fatty acid (FA) profile and FA metabolism may modify the risk of obesity-related diseases.

Methods:

We measured serum (n=122) and adipose tissue (n=24) FA composition and adipose tissue mRNA expression of genes regulating FA metabolism (n=100) in participants of the Kuopio Obesity Surgery Study (KOBS, age 47.2±8.7 years, BMI 44.6±6.0, 40 men, 82 women) before and one year after obesity surgery. As part of the surgery protocol, all the subjects were instructed to add sources of unsaturated fatty acids, such as rapeseed oil and fatty fish, into their diet. The results were compared with changes in serum FA composition in 122 subjects from the Finnish Diabetes Prevention study (DPS) (age 54.3±7.1 years, BMI 32.2±4.6, 28 men, 94 women).

Results:

The proportion of saturated FAs decreased and the proportion of n-3 and n-6 FAs increased in serum triglycerides after obesity surgery (all P<0.002). Weight loss predicted changes in quantitative amounts of saturated FAs, monounsaturated FAs, n-3 and n-6 FAs in triglycerides (P<0.002 for all). Moreover, the changes in adipose tissue FAs reflected the changes in serum FAs, and some of the changes were associated with mRNA expression of elongases and desaturases in adipose tissue (all P<0.05). In line with this the estimated activity of elongase (18:1 n-7/16:1 n-7) increased significantly after obesity surgery in all lipid fractions (all P<4 × 10⁻⁷) and the increase in the estimated activity of D5D in triglycerides was associated with higher weight loss (r=0.415, P<2 × 10⁻⁶). Changes in serum FA profile were similar after obesity surgery and lifestyle intervention, except for the change in the absolute amounts of n-3 FAs between the two studies (P=0.044).

Conclusions:

Beneficial changes in serum and adipose tissue FAs after obesity surgery could be associated with changes in endogenous metabolism and diet.

High Dietary Intake of Specific Fatty Acids Increases Risk of Flares in Patients With Ulcerative Colitis in Remission During Treatment With Aminosalicylates

BACKGROUND & AIMS

Dietary factors may have a significant role in relapse of disease among patients with ulcerative colitis (UC). However, the relationship between diet and UC is inadequately understood. We analyzed data from the diet's role in exacerbations of mesalamine maintenance study to determine whether dietary factors affect the risk of disease flares in patients with UC.

METHODS

We performed a prospective, multicenter, observational study of 412 patients, from 25 sites, with UC in remission during monotherapy with an aminosalicylate. Patients completed a validated food frequency questionnaire at enrollment and were followed for 12 months. We analyzed the relationship between diet and disease remission or flare for groups of macronutrients and micronutrients, and food groups previously associated with an increased risk of flare.

RESULTS

Forty-five patients (11%) had a UC relapse within 1 year of study enrollment. When analyzed in tertiles, increasing intake of multiple fatty acids was associated with increasing odds of relapse. In multivariable logistic regression analysis, only myristic acid (odds ratio, 3.01; 95% confidence interval, 1.17-7.74) maintained this dose-response relationship. Other foods previously implicated in flares of UC, such as processed meat, alcohol, and foods high in sulfur, were not associated with an increased risk of flare.

CONCLUSIONS

In a prospective study of more than 400 patients with UC undergoing treatment with aminosalicylates, we associated high dietary intake of specific fatty acids, including myristic acid (commonly found in palm oil, coconut oil, and dairy fats) with an increased risk of flare. These findings can help design interventional studies to evaluate dietary factors in UC.

Alterations of specific lipid groups in serum of obese humans: a review

Obesity is a major contributor to the dysfunction of liver, cardiac, pulmonary, endocrine and reproductive system, as well as a component of metabolic syndrome. Although development of obesity-related disorders is associated with lipid abnormalities, most previous studies dealing with the problem in question were limited to routinely determined parameters, such as serum concentrations of triacylglycerols, total cholesterol, low-density and high-density lipoprotein cholesterol. Many authors postulated to extend the scope of analysed lipid compounds and to study obesity-related alterations in other, previously non-examined groups of lipids. Comprehensive quantitative, structural and functional analysis of specific lipid groups may result in identification of new obesity-related alterations. The review summarizes available evidence of obesity-related alterations in various groups of lipids and their impact on health status of obese subjects. Further, the role of diet and endogenous lipid synthesis in the development of serum lipid alterations is discussed, along with potential application of various lipid compounds as risk markers for obesity-related comorbidities.

Dietary marine-derived long-chain monounsaturated fatty acids and cardiovascular disease risk: a mini review

Regular fish/fish oil consumption is widely recommended for protection against cardiovascular diseases (CVD). Fish and other marine life are rich sources of the cardioprotective long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) eicosapentaenoic acid (C20:5 n-3; EPA) and docosahexaenoic acid (C22:6 n-3; DHA). The lipid content and fatty acid profile of fish, however, vary greatly among different fish species. In addition to n-3 PUFA, certain fish, such as saury, pollock, and herring, also contain high levels of long-chain monounsaturated fatty acids (LCMUFA), with aliphatic tails longer than 18 C atoms (i.e., C20:1 and C22:1 isomers). Compared with well-studied n-3 PUFA, limited information, however, is available on the health benefits of marine-derived LCMUFA, particularly in regard to CVD. Our objective in this review is to summarize the current knowledge and provide perspective on the potential therapeutic value of dietary LCMUFA-rich marine oil for improving CVD risk factors. We will also review the possible mechanisms of LCMUFA action on target tissues. Finally, we describe the epidemiologic data and small-scaled clinical studies that have been done on marine oils enriched in LCMUFA. Although there are still many unanswered questions about LCMUFA, this appears to be promising new area of research that may lead to new insights into the health benefits of a different component of fish oils besides n-3 PUFA.

High-fat diet modifies the PPAR-γ pathway leading to disruption of microbial and physiological ecosystem in murine small intestine

Diet is among the most important factors contributing to intestinal homeostasis, and basic functions performed by the small intestine need to be tightly preserved to maintain health. Little is known about the direct impact of high-fat (HF) diet on small-intestinal mucosal defenses and spatial distribution of the microbiota during the early phase of its administration. We observed that only 30 d after HF diet initiation, the intervillous zone of the ileum-which is usually described as free of bacteria-became occupied by a dense microbiota. In addition to affecting its spatial distribution, HF diet also drastically affected microbiota composition with a profile characterized by the expansion of Firmicutes (appearance of Erysipelotrichi), Proteobacteria (Desulfovibrionales) and Verrucomicrobia, and decrease of Bacteroidetes (family S24-7) and Candidatus arthromitus A decrease in antimicrobial peptide expression was predominantly observed in the ileum where bacterial density appeared highest. In addition, HF diet increased intestinal permeability and decreased cystic fibrosis transmembrane conductance regulator (Cftr) and the Na-K-2Cl cotransporter 1 (Nkcc1) gene and protein expressions, leading to a decrease in ileal secretion of chloride, likely responsible for massive alteration in mucus phenotype. This complex phenotype triggered by HF diet at the interface between the microbiota and the mucosal surface was reversed when the diet was switched back to standard composition or when mice were treated for 1 wk with rosiglitazone, a specific agonist of peroxisome proliferator-activated receptor-γ (PPAR-γ). Moreover, weaker expression of antimicrobial peptide-encoding genes and intervillous bacterial colonization were observed in Ppar-γ-deficient mice, highlighting the major role of lipids in modulation of mucosal immune defenses.

Dietary Interventions and Changes in Cardio-Metabolic Parameters in Metabolically Healthy Obese Subjects: A Systematic Review with Meta-Analysis

The aim of this systematic review was to assess the effect of diet on changes in parameters describing the body size phenotype of metabolically healthy obese subjects. The databases Medline, Scopus, Web of Knowledge and Embase were searched for clinical studies carried out between 1958 and June 2016 that reported the effect of dietary intervention on BMI, blood pressure, concentration of fasting triglyceride (TG), high density lipoprotein cholesterol (HDL-C), fasting glucose level, the homoeostatic model assessment of insulin resistance (HOMA-IR) and high sensitivity C-Reactive Protein (hsCRP) in metabolically healthy, obese subjects. Twelve clinical studies met inclusion criteria. The combined analyzed population consists of 1827 subjects aged 34.4 to 61.1 with a BMI > 30 kg/m². Time of intervention ranged from eight to 104 weeks. The baseline characteristics related to lipid profile were more favorable for metabolically healthy obese than for metabolically unhealthy obese. The meta-analyses revealed a significant associations between restricted energy diet and BMI (95% confidence interval (CI): -0.88, -0.19), blood pressure (systolic blood pressure (SBP): -4.73 mmHg; 95% CI: -7.12, -2.33; and diastolic blood pressure (DBP): -2.75 mmHg; 95% CI: -4.30, -1.21) and TG (-0.11 mmol/l; 95% CI: -0.16, -0.06). Changes in fasting glucose, HOMA-IR and hsCRP did not show significant changes. Sufficient evidence was not found to support the use of specific diets in metabolically healthy obese subjects. This analysis suggests that the effect of caloric restriction exerts its effects through a reduction in BMI, blood pressure and triglycerides in metabolically healthy obese (MHO) patients.

Relationship between Body Mass Index, C-Peptide, and Delta-5-Desaturase Enzyme Activity Estimates in Adult Males

Obesity, in particular abdominal obesity, alters the composition of plasma and tissue fatty acids (FAs), which contributes to inflammation and insulin resistance. FA metabolism is modulated by desaturases and may affect adipokine and insulin secretion. Therefore, we examined relationships between adipokines, a marker of insulin production, and plasma FA desaturase enzyme activity estimates (EAEs) in obesity. Plasma phospholipid (PPL) FAs were isolated from 126 males (ages 48 to 65 years), derivatized, and analyzed using gas chromatography. Delta-6 desaturase (D6D) and delta-5 desaturase (D5D) EAEs were calculated as the ratio of PPL 20:3/18:2 and 20:4/20:3, respectively. In body mass index (BMI) and waist circumference (WC) adjusted polytomous logistic regression analyses, PPL FAs and FA desaturase EAEs were associated with C-peptide and adiponectin. Individuals with elevated D6D EAEs were less likely (OR 0.33) to have serum adiponectin concentrations > 5.37 μg/mL, compared with adiponectin concentrations ≤ 3.62 μg/mL. Individuals with increased D5D EAEs were less likely (OR 0.8) to have C-peptide concentrations ≥ 3.32 ng/mL, and > 1.80 and ≤ 3.29 ng/mL, compared with those with C-peptide ≤ 1.76 ng/mL. The proinflammatory cytokine tumor necrosis factor-α (TNF- α) was positively associated with C-peptide, but TNF- α was not associated with the D5D EAE. C-peptide and adiponectin concentrations are associated with specific PPL FAs and FA desaturase EAEs. The relationship between C-peptide concentrations and D5D EAEs remained significant after adjusting for BMI, WC, and TNF-α. Thus, future research should investigate whether D5D inhibition may occur through a C-peptide mediated pathway.

Hepatic fat content is a determinant of metabolic phenotypes and increased carotid intima-media thickness in obese adults

Individuals with metabolically healthy obesity (MHO) are at relatively low risk for the development of metabolic abnormalities and subclinical atherosclerosis. This study aims to examine whether hepatic fat accumulation determines metabolic phenotype of obesity and associated with subclinical atherosclerosis. A total of 485 obese adults (aged 40–65 years) who received magnetic resonance spectroscopy were divided into metabolically abnormally obesity (MAO) and MHO groups according to metabolic status. MHO individuals had lower levels of intrahepatic triglyceride (IHTG) content and carotid intima-media thickness (CIMT) than MAO individuals. In multivariable linear regression analyses, IHTG content was independently associated with metabolic syndrome components and CIMT. Based on receiver operating characteristic curve analysis, the IHTG content displayed a higher area under the curve (AUC) for detecting the MAO phenotype (AUC = 0.70, 95%CI = 0.65–0.75) and increased CIMT (AUC = 0.60, 95%CI = 0.54–0.66) than BMI, waist circumference, and body fat percent. MHO individuals were 1.9 times (p < 0.001) more likely to have metabolic syndrome per 1 SD change in IHTG content in multivariable-adjusted models. Likewise, the risk for high CIMT increased 29% per 1 SD change in IHTG content [OR (95% CI):1.29(1.01–1.64)]. These findings suggest that hepatic fat is a potential predictor of metabolically unhealthy obesity phenotype and subclinical atherosclerosis.

Circulating Unsaturated Fatty Acids Delineate the Metabolic Status of Obese Individuals

Background

Obesity is not a homogeneous condition across individuals since about 25–40% of obese individuals can maintain healthy status with no apparent signs of metabolic complications. The simple anthropometric measure of body mass index does not always reflect the biological effects of excessive body fat on health, thus additional molecular characterizations of obese phenotypes are needed to assess the risk of developing subsequent metabolic conditions at an individual level.

Methods

To better understand the associations of free fatty acids (FFAs) with metabolic phenotypes of obesity, we applied a targeted metabolomics approach to measure 40 serum FFAs from 452 individuals who participated in four independent studies, using an ultra-performance liquid chromatograph coupled to a Xevo G2 quadruple time-of-flight mass spectrometer.

Findings

FFA levels were significantly elevated in overweight/obese subjects with diabetes compared to their healthy counterparts. We identified a group of unsaturated fatty acids (UFAs) that are closely correlated with metabolic status in two groups of obese individuals who underwent weight loss intervention and can predict the recurrence of diabetes at two years after metabolic surgery. Two UFAs, dihomo-gamma-linolenic acid and palmitoleic acid, were also able to predict the future development of metabolic syndrome (MS) in a group of obese subjects.

Interpretation

These findings underscore the potential role of UFAs in the MS pathogenesis and also as important markers in predicting the risk of developing diabetes in obese individuals or diabetes remission after a metabolic surgery.

•

Four independent studies were applied to examine the association of free fatty acids with metabolic status of obesity.

•

Our data supported an important role for unsaturated fatty acids in the pathogenesis of metabolic syndrome.

•

Two unsaturated fatty acids were predictive of future diabetes risk and diabetes remission after metabolic surgery.

About 25–40% of obese individuals, defined by the body mass index, are metabolically healthy. Because obesity is a risk factor for developing type 2 diabetes, it is important to monitor obese individuals for changes in metabolic status. Simpler means of assessing the efficacy of surgical or dietary interventions are also desirable. We examined blood fatty acid levels in patients to locate potential biomarkers that would signify either greater risk of diabetes acquisition or effectiveness of diabetes treatment. Two unsaturated fatty acids, dihomo-gamma-linolenic acid and palmitoleic acid, were shown to predict acquisition of diabetes and also evaluate diabetes remission post-metabolic surgery.

Metabolomics Reveals Metabolically Healthy and Unhealthy Obese Individuals Differ in their Response to a Caloric Challenge

OBJECTIVE

To determine if metabolically healthy obese (MHO) individuals have a different metabolic response to a standardized diet compared to lean healthy (LH) and metabolically unhealthy obese (MUO) individuals.

METHODS

Thirty adults (35-70 yrs) were classified as LH, MHO, and MUO according to anthropometric and clinical measurements. Participants consumed a standardized high calorie meal (~1330 kcal). Blood glucose and insulin were measured at fasting, and 15, 30, 60, 90 and 120 min postprandially. Additional blood samples were collected for the targeted analysis of amino acids (AAs) and derivatives, and fatty acids (FAs).

RESULTS

The postprandial response (i.e., area under the curve, AUC) for serum glucose and insulin were similar between MHO and LH individuals, and significantly lower than MUO individuals (p < 0.05). Minor differences were found in postprandial responses for AAs between MHO and MUO individuals, while three polyunsaturated FAs (linoleic acid, γ-linolenic acid, arachidonic acid) showed smaller changes in serum after the meal in MHO individuals compared to MUO. Fasting levels for various AAs (notably branched-chain AA) and FAs (e.g., saturated myristic and palmitic acids) were found to correlate with glucose and insulin AUC.

CONCLUSION

MHO individuals show preserved insulin sensitivity and a greater ability to adapt to a caloric challenge compared to MUO individuals.

Plasma phospholipids, non-esterified plasma polyunsaturated fatty acids and oxylipids are associated with BMI

The obese lipid profile is associated with increased free fatty acids and triacylglycerides. Currently, little is known about the plasma lipid species associated with obesity. In this study, we compared plasma lipid fatty acid (FA) profiles as a function of BMI. Profiling phospholipid (PL) FAs and their respective oxylipids could predict which obese individuals are more likely to suffer from diseases associated with chronic inflammation or oxidative stress. We investigated the relationship between BMI and plasma PL (PPL) FA composition in 126 men using a quantitative gas chromatography analysis. BMI was inversely associated with both PPL nervonic and linoleic acid (LA) but was positively associated with both dihomo-γ-linolenic and palmitoleic acid. Compared to lean individuals, obese participants were more likely to have ω-6 FAs, except arachidonic acid and LA, incorporated into PPLs. Obese participants were less likely to have EPA and DHA incorporated into PPLs compared to lean participants. Non-esterified plasma PUFA and oxylipid analysis showed ω-6 oxylipids were more abundant in the obese plasma pool. These ω-6 oxylipids are associated with increased angiogenesis (i.e. epoxyeicosatrienoates), reactive oxygen species (i.e. 9-hydroxyeicosatetraenoate), and inflammation resolution (i.e. Lipoxin A4). In summary, BMI is directly associated with specific PPL FA and increased ω-6 oxylipids.

Associations of dairy intake with glycemia and insulinemia, independent of obesity, in Brazilian adults: the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

BACKGROUND

Inverse associations between dairy intake and the risk of type 2 diabetes have been shown, but more studies are needed, especially from low- and middle-income countries.

OBJECTIVE

The objective was to describe the association between dairy products and direct measures of glycemic status in adults without known diabetes.

DESIGN

The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) includes 15,105 adults, aged 35-74 y, enrolled from universities and research institutions in 6 Brazilian capital cities. We excluded participants with a known diabetes diagnosis, cardiovascular diseases, and cancer. Dairy consumption was assessed by a food-frequency questionnaire, and we computed servings per day for total and subgroups of dairy. Associations with fasting blood glucose (FG) and fasting insulin, 2-h postload glucose (PG), 2-h postload insulin (PI), glycated hemoglobin (Hb A1c), and homeostasis model assessment of insulin resistance (HOMA-IR) were assessed through multivariable linear regression analysis with adjustment for demographic characteristics, behavioral risk factors, other dietary factors, and anthropometric measurements.

RESULTS

The sample size after exclusions was 10,010. The intake of total dairy was inversely associated with FG (linear β for dairy servings/d = -0.46 ± 0.2 mg/dL), PG (-1.25 ± 0.5 mg/dL), PI (-1.52 ± 0.6 mg/dL), Hb A1c (-0.02 ± 0.0%), and HOMA-IR (-0.04 ± 0.0) after adjustment for all covariates (P < 0.05 for all). The findings were consistent across categories of sex, race, obesity status, and dairy fat amount (reduced-fat vs. full-fat dairy). Fermented dairy products showed particularly strong inverse associations with the outcomes, with adjusted differences for a 1-serving/d increment of -0.24 (95% CI: -0.46, -0.02) mg/dL for FG, -0.86 (-1.42, -0.30) mg/dL for PG, and -0.01% (-0.02%, 0.00%) for Hb A1c. Myristic acid was the only nutrient that appeared to mediate the association between dairy intake and glycemia.

CONCLUSION

Dairy intake, especially fermented dairy, was inversely associated with measures of glycemia and insulinemia in Brazilian adults without diagnosed diabetes. This trial was registered at clinicaltrials.com as NCT02320461.

Gender-specific association of oxidative stress and inflammation with cardiovascular risk factors in Arab population

Background. The impact of gender difference on the association between metabolic stress and cardiovascular disease (CVD) remains unclear. We have investigated, for the first time, the gender effect on the oxidative and inflammatory stress responses and assessed their correlation with classical cardiometabolites in Arab population. Methods. A total of 378 adult Arab participants (193 females) were enrolled in this cross-sectional study. Plasma levels of CRP, IL-6, IL-8, TNF-α, ROS, TBARs, and PON1 were measured and correlated with anthropometric and cardiometabolite parameters of the study population. Results. Compared to females, males had significantly higher FBG, HbA1c, TG, and blood pressure but lower BMI, TC, and HDL (P < 0.05). After adjustment for BMI and WC, females had higher levels of ROS, TBARS, and CRP (P < 0.001) whereas males had increased levels of IL-8, IL-6, and TNF-α (P < 0.05). Moreover, after adjustment for age, BMI, and gender, the levels of TNF-α, IL-6, and ROS were associated with central obesity but not general obesity. Conclusion. Inflammation and oxidative stress contribution to CVD risk in Arab population linked to gender and this risk is better reflected by central obesity. Arab females might be at risk of CVD complications due to increased oxidative stress.

Adipose tissue dysregulation and metabolic consequences in childhood and adolescent obesity: potential impact of dietary fat quality

Evidence suggests that at a population level, childhood and adolescent obesity increase the long-term risk of chronic diseases such as type 2 diabetes and CVD. At an individual level, however, the metabolic consequences of obesity in youth vary immensely. Despite comparable BMI, some adolescents develop impaired glucose tolerance while others maintain normal glucose homeostasis. It has been proposed that the variation in the capacity to store lipid in the subcutaneous adipose tissue (SAT) may partially discriminate metabolically healthy from unhealthy obesity. In positive energy balance, a decreased capacity to expand SAT may drive lipid accumulation to visceral adipose tissue, liver and skeletal muscle. This state of lipotoxicity is associated with chronic low-grade inflammation, insulin resistance and dyslipidaemia. The present review examines the differential adipose tissue development and function in children and adolescents who exhibit metabolic dysregulation compared with those who are protected. Additionally, the role of manipulating dietary fat quality to potentially prevent and treat metabolic dysfunction in obesity will be discussed. The findings of the present review highlight the need for further randomised controlled trials to establish the effect of dietary n-3 PUFA on the metabolic phenotype of obese children and adolescents. Furthermore, using a personalised nutrition approach to target interventions to those at risk of, or those with established metabolic dysregulation may optimise the efficacy of modifying dietary fat quality.

Molecular insights into the role of white adipose tissue in metabolically unhealthy normal weight and metabolically healthy obese individuals

Obesity is a risk factor for the development of type 2 diabetes and cardiovascular disease. However, it is now recognized that a subset of individuals have reduced cardiometabolic risk despite being obese. Paradoxically, a subset of lean individuals is reported to have high risk for cardiometabolic complications. These distinct subgroups of individuals are referred to as metabolically unhealthy normal weight (MUNW) and metabolically healthy obese (MHO). Although the clinical relevance of these subgroups remains debated, evidence shows a critical role for white adipose tissue (WAT) function in the development of these phenotypes. The goal of this review is to provide an overview of our current state of knowledge regarding the molecular and metabolic characteristics of WAT associated with MUNW and MHO. In particular, we discuss the link between different WAT depots, immune cell infiltration, and adipokine production with MUNW and MHO. Furthermore, we also highlight recent molecular insights made with genomic technologies showing that processes such as oxidative phosphorylation, branched-chain amino acid catabolism, and fatty acid β-oxidation differ between these phenotypes. This review provides evidence that WAT function is closely linked with cardiometabolic risk independent of obesity and thus contributes to the development of MUNW and MHO.

Rapid growth and childhood obesity are strongly associated with lysoPC(14:0)

BACKGROUND

Despite the growing interest in the early-origins-of-later-disease hypothesis, little is known about the metabolic underpinnings linking infant weight gain and childhood obesity.

OBJECTIVE

To discover biomarkers reflective of weight change in the first 6 months and overweight/obesity at age 6 years via a targeted metabolomics approach.

DESIGN

This analysis comprised 726 infants from a European multicenter randomized trial (Childhood Obesity Programme, CHOP) for whom plasma blood samples at age 6 months and anthropometric data up to the age of 6 years were available. 'Rapid growth' was defined as a positive difference in weight within the first 6 months of life standardized to WHO growth standards. Weight change was regressed on each of 168 metabolites (acylcarnitines, lysophosphatidylcholines, sphingomyelins, and amino acids). Metabolites significant after Bonferroni's correction were tested as predictors of later overweight/obesity.

RESULTS

Among the overall 19 significant metabolites, 4 were associated with rapid growth and 15 were associated with a less-than-ideal weight change. After adjusting for feeding group, only the lysophosphatidylcholine LPCaC14:0 remained significantly associated with rapid weight gain (β = 0.18). Only LPCaC14:0 at age 6 months was predictive of overweight/obesity at age 6 years (OR 1.33; 95% CI 1.04-1.69).

CONCLUSION

LPCa14:0 is strongly related to rapid growth in infancy and childhood overweight/obesity. This suggests that LPCaC14:0 levels may represent a metabolically programmed effect of infant weight gain on the later obesity risk. However, these results require confirmation by independent cohorts.

Inflammation as a link between obesity, metabolic syndrome and type 2 diabetes

It is recognized that a chronic low-grade inflammation and an activation of the immune system are involved in the pathogenesis of obesity-related insulin resistance and type 2 diabetes. Systemic inflammatory markers are risk factors for the development of type 2 diabetes and its macrovascular complications. Adipose tissue, liver, muscle and pancreas are themselves sites of inflammation in presence of obesity. An infiltration of macrophages and other immune cells is observed in these tissues associated with a cell population shift from an anti-inflammatory to a pro-inflammatory profile. These cells are crucial for the production of pro-inflammatory cytokines, which act in an autocrine and paracrine manner to interfere with insulin signaling in peripheral tissues or induce β-cell dysfunction and subsequent insulin deficiency. Particularly, the pro-inflammatory interleukin-1β is implicated in the pathogenesis of type 2 diabetes through the activation of the NLRP3 inflammasome. The objectives of this review are to expose recent data supporting the role of the immune system in the pathogenesis of insulin resistance and type 2 diabetes and to examine various mechanisms underlying this relationship. If type 2 diabetes is an inflammatory disease, anti-inflammatory therapies could have a place in prevention and treatment of type 2 diabetes.