Adapting to obesity with adipose tissue inflammation

A novel small molecule A2A adenosine receptor agonist, indirubin-3′-monoxime, alleviates lipid-induced inflammation and insulin resistance in 3T3-L1 adipocytes

Saturated free fatty acid-induced adipocyte inflammation plays a pivotal role in implementing insulin resistance and type 2 diabetes. Recent reports suggest A2A adenosine receptor (A2AAR) could be an attractive choice to counteract adipocyte inflammation and insulin resistance. Thus, an effective A2AAR agonist devoid of any toxicity is highly appealing. Here, we report that indirubin-3′-monoxime (I3M), a derivative of the bisindole alkaloid indirubin, efficiently binds and activates A2AAR which leads to the attenuation of lipid-induced adipocyte inflammation and insulin resistance. Using a combination of in silico virtual screening of potential anti-diabetic candidates and in vitro study on insulin-resistant model of 3T3-L1 adipocytes, we determined I3M through A2AAR activation markedly prevents lipid-induced impairment of the insulin signaling pathway in adipocytes without any toxic effects. While I3M restrains lipid-induced adipocyte inflammation by inhibiting NF-κB dependent pro-inflammatory cytokines expression, it also augments cAMP-mediated CREB activation and anti-inflammatory state in adipocytes. However, these attributes were compromised when cells were pretreated with the A2AAR antagonist, SCH 58261 or siRNA mediated knockdown of A2AAR. I3M, therefore, could be a valuable option to intervene adipocyte inflammation and thus showing promise for the management of insulin resistance and type 2 diabetes.

Gain of Metabolic Benefit with Ablation of miR-149-3p from Subcutaneous Adipose Tissue in Diet-Induced Obese Mice

The global rise in obesity has become a public health crisis. During the onset of obesity, disrupted catecholamine signals have been described to contribute to excess fat accumulation, however, the molecular and metabolic change of subcutaneous adipose tissue (SAT) upon chronic high-fat feeding has rarely been investigated. Here, we show that chronic high-fat feeding caused a significant decrease in the expression of thermogenic genes and acquisition of partial deleterious features of visceral fat in SAT. Upregulated miR-149-3p was involved in this obesity-induced "visceralization" of SAT via inhibiting PRDM16, a master regulator that promoted SAT thermogenesis. Reduction of miR-149-3p significantly increased PRDM16 expression in SAT, with improved whole-body insulin sensitivity, decreased SAT inflammation, and liver steatosis in high-fat fed mice. These findings provided direct evidence of the anti-obese and anti-diabetic effect of PRDM16 in the obese background for the first time and identified that miR-149-3p could serve as a therapeutic target to protect against diet-induced obesity and metabolic dysfunctions.

Endothelial-to-Mesenchymal Transition in Human Adipose Tissue Vasculature Alters the Particulate Secretome and Induces Endothelial Dysfunction

OBJECTIVE

Endothelial cells (EC) in obese adipose tissue (AT) are exposed to a chronic proinflammatory environment that may induce a mesenchymal-like phenotype and altered function. The objective of this study was to establish whether endothelial-to-mesenchymal transition (EndoMT) is present in human AT in obesity and to investigate the effect of such transition on endothelial function and the endothelial particulate secretome represented by extracellular vesicles (EV). Approach and Results: We identified EndoMT in obese human AT depots by immunohistochemical co-localization of CD31 or vWF and α-SMA (alpha-smooth muscle actin). We showed that AT EC exposed in vitro to TGF-β (tumor growth factor-β), TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-γ) undergo EndoMT with progressive loss of endothelial markers. The phenotypic change results in failure to maintain a tight barrier in culture, increased migration, and reduced angiogenesis. EndoMT also reduced mitochondrial oxidative phosphorylation and glycolytic capacity of EC. EVs produced by EC that underwent EndoMT dramatically reduced angiogenic capacity of the recipient naïve ECs without affecting their migration or proliferation. Proteomic analysis of EV produced by EC in the proinflammatory conditions showed presence of several pro-inflammatory and immune proteins along with an enrichment in angiogenic receptors.

CONCLUSIONS

We demonstrated the presence of EndoMT in human AT in obesity. EndoMT in vitro resulted in production of EV that transferred some of the functional and metabolic features to recipient naïve EC. This result suggests that functional and molecular features of EC that underwent EndoMT in vivo can be disseminated in a paracrine or endocrine fashion and may induce endothelial dysfunction in distant vascular beds.

Effect of whole foods and dietary patterns on markers of subclinical inflammation in weight-stable overweight and obese adults: a systematic review

Context

Reduction of subclinical inflammation is a potential target for chronic disease management. Adiposity is a known modifier of meta-inflammation; however, the influence of dietary factors is less clear.

Objective

This review examines evidence from human trials evaluating effects of whole foods or dietary patterns on circulating inflammatory markers in weight-stable overweight and obese adults. It is the first review to investigate effects of diet on inflammation, independent of changes in adiposity.

Data Sources

The Ovid MEDLINE, EMBASE, CINAHL, and Cochrane databases were searched.

Data Extraction

Data extraction was conducted using the Cochrane Collaboration Handbook for Systematic Reviews of Interventions.

Data Analysis

Study quality was evaluated using the Cochrane Collaboration Risk of Bias Assessment tool. Thirty-three studies were included assessing effects of 17 foods and dietary patterns on 39 inflammatory markers.

Conclusions

Overall, foods and dietary patterns were not found to have significant effects on inflammatory markers in weight-stable individuals. Inconsistencies among studies were largely due to methodological limitations. Future research should invest in longer intervention periods and standardization of inflammatory marker panels paired with novel technologies, while ensuring anthropometric measures are monitored and adequately controls are used.

Systematic Review Registration

Prospero registration number CRD42017067765.

Obesity associated with coal ash inhalation triggers systemic inflammation and oxidative damage in the hippocampus of rats

People with large amounts of adipose tissue are more vulnerable and more likely to develop diseases where oxidative stress and inflammation play a pivotal role, than persons with a healthy weight. Atmospheric contamination is a reality to which a large part of the worldwide population is exposed. Half of today's global electrical energy is derived from coal. Each organism, in its complexity, responds in different ways to dietary compounds and air pollution. The objective of this study was to investigate the effects of obesity and coal ash inhalation within the parameters of oxidative damage and inflammation in different regions of the brain of rats. A diet containing high-fat concentration was administered chronically to rats, along with exposure to coal ash, simulating the contamination that occurs daily throughout human life. High-resolution transmission electron microscopy was performed to identify the particles present in coal ash samples. Our results demonstrated that obese rats exposed to coal ash inhalation were more affected by oxidative damage with subsequent systemic inflammation in the hippocampus. Since there is an inflammatory predisposition caused by obesity, the inhalation of nanoparticles increases the levels of free radicals, resulting in systemic inflammation and oxidative damage, which can lead to chronic neurodegeneration.

The Obesity Paradox in Cancer, Tumor Immunology, and Immunotherapy: Potential Therapeutic Implications in Triple Negative Breast Cancer

Cancer immunotherapy has been heralded as a breakthrough cancer treatment demonstrating tremendous success in improving tumor responses and survival of patients with hematological cancers and solid tumors. This novel promising treatment approach has in particular triggered optimism for triple negative breast cancer (TNBC) treatment, a subtype of breast cancer with distinct clinical features and poor clinical outcome. In early 2019, the FDA granted the first approval of immune checkpoint therapy, targeting PD-L1 (Atezolizumab) in combination with chemotherapy for the treatment of patients with locally advanced or metastatic PD-L1 positive TNBC. The efficacy of immuno-based interventions varies across cancer types and patient cohorts, which is attributed to a variety of lifestyle, clinical, and pathological factors. For instance, obesity has emerged as a risk factor for a dampened anti-tumor immune response and increased risk of immunotherapy-induced immune-related adverse events (irAEs) but has also been linked to improved outcomes with checkpoint blockade. Given the breadth of the rising global obesity epidemic, it is imperative to gain insight into the immunomodulatory effects of obesity in the peripheral circulation and within the tumor microenvironment. In this review, we resolve the impact of obesity on breast tumorigenesis and progression on the one hand, and on the immune contexture on the other hand. Finally, we speculate on the potential implications of obesity on immunotherapy response in breast cancer. This review clearly highlights the need for in vivo obese cancer models and representative clinical cohorts for evaluation of immunotherapy efficacy.

Anti-inflammatory effect of β2 adrenergic stimulation on circulating monocytes with a pro-inflammatory state in high-fat diet-induced obesity

Obesity is a chronic condition associated with low-grade inflammation, and it also involves alterations of the function of the hypothalamic-pituitaryadrenal axis and the sympathetic nervous system. Adrenergic agonists such as catecholamines are important immunoregulatory molecules that are involved in modulating both metabolism and most of the mechanisms of the immune response. The first objective of this study was to determine whether the systemic inflammatory state associated with obesity is also manifested in the inflammatory profile and phenotype of circulating monocytes; and the second objective was to evaluate the effects of β2 adrenergic stimulation on the inflammatory profile and phenotype of monocytes in obesity, and whether this response could be different from that in lean individuals. C57BL/6J mice were randomly allocated to one of two diets for 18 weeks: high-fat diet in order to obtain an experimental model of obesity, and standard diet in the control lean group. Circulating monocyte expression of inflammatory cytokines (MCP-1, TNF-α, IL-8, IL-6, IL-10, and TGF-β), surface membrane marker Ly6C, inducible nitric oxide synthase and arginase-1, and Toll-like receptor 4 were evaluated through flow cytometry in the presence or absence of selective β2 adrenergic receptor agonist terbutaline. Monocytes from high-fat diet-induced obese animals presented higher expression levels of all pro-inflammatory cytokines and a higher percentage of monocytes with a pro-inflammatory phenotype than those from lean animals. β2 adrenergic stimulation induced a shift towards an anti-inflammatory activity profile and phenotype in obese mice, whereas it induced a shift towards a pro-inflammatory activity profile and phenotype in lean mice. In conclusion, β2 adrenergic stimulation in monocytes was anti-inflammatory only in obese animals, which presented a pro-inflammatory state at baseline.

Allostatic load and executive functions in overweight adults

BACKGROUND/OBJECTIVE

Overweight is linked to inflammatory and neuroendocrine responses potentially prompting deregulations in biological systems harmful to the brain, particularly to the prefrontal cortex. This structure is crucial for executive performance, ultimately supervising behaviour. Thus, in the present work, we aimed to test the relationship between allostatic load increase, a surrogate of chronic physiological stress, and core executive functions, such as cognitive flexibility, inhibitory control, and working memory.

METHOD

Forty-seven healthy-weight and 56 overweight volunteers aged from 21 to 40 underwent medical and neuropsychological examination.

RESULTS

Overweight subjects exhibited a greater allostatic load index than healthy-weight individuals. Moreover, the allostatic load index was negatively related to inhibitory control. When separated, the link between allostatic load index and cognitive flexibility was more marked in the overweight group.

CONCLUSIONS

An overweight status was linked to chronic physiological stress. The inverse relationship between the allostatic load index and cognitive flexibility proved stronger in this group. Set-shifting alterations could sustain rigid-like behaviours and attitudes towards food.

Adipogenesis: A Necessary but Harmful Strategy

Obesity is considered to significantly increase the risk of the development of a vast range of metabolic diseases. However, adipogenesis is a complex physiological process, necessary to sequester lipids effectively to avoid lipotoxicity in other tissues, like the liver, heart, muscle, essential for maintaining metabolic homeostasis and has a crucial role as a component of the innate immune system, far beyond than only being an inert mass of energy storage. In pathophysiological conditions, adipogenesis promotes a pro-inflammatory state, angiogenesis and the release of adipokines, which become dangerous to health. It results in a hypoxic state, causing oxidative stress and the synthesis and release of harmful free fatty acids. In this review, we try to explain the mechanisms occurring at the breaking point, at which adipogenesis leads to an uncontrolled lipotoxicity. This review highlights the types of adipose tissue and their functions, their way of storing lipids until a critical point, which is associated with hypoxia, inflammation, insulin resistance as well as lipodystrophy and adipogenesis modulation by Krüppel-like factors and miRNAs.

High abdominal adiposity and low phase angle in overweight renal transplant recipients

Obesity is associated with increased risk of cardiovascular disease (CVD). Body mass index (BMI) is the most used parameter for obesity screening. However, the evaluation of CVD risk in overweight individuals should include the assessment of body fat distribution and body composition. Renal transplant recipients (RTR) have a high CVD risk and frequently present weight gain and loss of lean mass. The aim of this study was to evaluate body fat distribution and body composition in overweight RTR. This cross-sectional study was conducted with 86 RTR and 86 hypertensive individuals (comparison group, CG) presenting BMI 25-35 Kg/m² and 45-70 years. Anthropometric evaluation included BMI, waist circumference, waist-to-height ratio, and a body shape index. Body composition was evaluated with bioelectrical impedance analysis (BIA). Glomerular filtration rate was estimated (eGFR) by CKD-EPI equation. RTR group (RTRG) and CG presented similar age and BMI. RTRG when compared to CG presented lower percentage of women and eGFR; higher central adiposity; and lower values of reactance, intracellular water, body cell mass and phase angle, more consistently observed in women. This study suggests that overweight RTR present higher abdominal adiposity and impairment in BIA parameters that are sensitive indicators of impaired membrane integrity, water distribution, and body cell mass.

Adipose-specific knockdown of Sirt1 results in obesity and insulin resistance by promoting exosomes release

Sirtuin1 (SIRT1) has recently emerged as a pivotal regulator of glucose metabolism and insulin sensitivity. However, the underlying mechanism has not been fully elucidated. In this study, we investigated the role of SIRT1 in the development of obesity and insulin resistance by generating mice with adipose-specific ablation of Sirt1 (Ad-Sirt1^-/- mice). Ad-Sirt1^-/- mice exhibited increased fat mass, impaired glucose tolerance, attenuated insulin sensitivity, and increased exosomes, whereas the administration of exosomes inhibitor effectively ameliorated the impaired metabolic profile in Ad-Sirt1^-/- mice. Moreover, the increased exosomes were proved to be a result of defective autophagy activity in Ad-Sirt1^-/- mice and restoration of SIRT1 activity efficiently improved metabolic profiles in vitro. Further study demonstrated that Sirt1 deficiency-induced exosomes modulated insulin sensitivity at least partially via the TLR4/NF-κB signaling pathway. Therefore, our findings implicated SIRT1 as a key factor in metabolic regulation, and adipose Sirt1 deficiency could exert an effect on the development of obesity and insulin resistance by promoting exosome release.

Obesity-Induced Adipose Tissue Inflammation as a Strong Promotional Factor for Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is expected to soon become the second leading cause of cancer related deaths in the United States. This may be due to the rising obesity prevalence, which is a recognized risk factor for PDAC. There is great interest in deciphering the underlying driving mechanisms of the obesity–PDAC link. Visceral adiposity has a strong correlation to certain metabolic diseases and gastrointestinal cancers, including PDAC. In fact, our own data strongly suggest that visceral adipose tissue inflammation is a strong promoter for PDAC growth and progression in a genetically engineered mouse model of PDAC and diet-induced obesity. In this review, we will discuss the relationship between obesity-associated adipose tissue inflammation and PDAC development, with a focus on the key molecular and cellular components in the dysfunctional visceral adipose tissue, which provides a tumor permissive environment.

Sugar in mind: Untangling a sweet and sour relationship beyond type 2 diabetes

It is widely recognised that type 2 diabetes (T2D) represents a major disease burden but it is only recently that its role in neurodegeneration has attracted more attention. This research has shown that T2D is associated with impaired cerebral health, cognitive decline and dementia. However, the impact on the brain of progressive metabolic changes associated with the pre-clinical development of the disease is less clear. The aim of this review is to comprehensively summarise how the emergence of risk factors and co-morbid conditions linked to the development of T2D impact cerebral health. Particular attention is directed at characterising how normal but elevated blood glucose levels in individuals without T2D contribute to neurodegenerative processes, and how the main risk factors for T2D including obesity, physical activity and diet modulate these effects. Where available, evidence from the animal and human literature is contrasted, and sex differences in risk and outcomes are highlighted.

Adipose circular RNAs exhibit dynamic regulation in obesity and functional role in adipogenesis

Non-coding RNAs are emerging as novel regulators in adipocyte differentiation and function. Circular RNAs (circRNAs) are a new class of non-coding transcripts generated across all eukaryotic tissues, but their function in adipose biology remains unknown. Here we perform deep sequencing of visceral and subcutaneous fat to discover thousands of adipose circRNAs, many of which are species conserved, tissue specific and dynamically regulated during adipogenesis and obesity. We identify circTshz2-1 and circArhgap5-2 as indispensable regulators of adipogenesis in vitro. To characterize the function of circRNAs in vivo, we deliver adenoviral shRNA targeting circArhgap5-2 into mouse inguinal tissue and show that the expression of this circRNA is essential in maintaining the global adipocyte transcriptional programme involved in lipid biosynthesis and metabolism. We also demonstrate that the pro-adipogenic function of circArhgap5-2 is conserved in human adipocytes. Our results provide important evidence that circRNAs serve as important regulators in adipocyte differentiation and metabolism.

An Interdisciplinary Weight Loss Program Improves Body Composition and Metabolic Profile in Adolescents With Obesity: Associations With the Dietary Inflammatory Index

Background and Aims: The prevalence of overweight and obesity consitutes a global epidemic and it is growing around the world. Food and nutrition are essential requirements for promoting health and protecting against non-communicable chronic diseases, such as obesity and cardiovascular disease. Specific dietary components may modulate inflammation and oxidative stress in obese individuals. The Dietary Inflammatory Index (DII®) was developed to characterize the anti- and pro-inflammatory effects of individuals' diet. Few studies have investigated the role of diet-associated inflammation in adolescents with obesity. The present study aims to investigate the effects of an interdisciplinary weight loss therapy on DII scores and cardiometabolic risk in obese adolescents and possibles correlations.

Methods: A total of 45 volunteers (14–19 years old) were recruited and enrolled for long-term interdisciplinary therapy including clinical, nutritional, psychological counseling, and exercise training. Adolescents had access to videos about health education weekly. Body composition and inflammatory and serum profiles were evaluated at baseline and after intervention. The food intake was obtained by 24-h food recall. Data was used to calculate energy-adjusted DII (E-DII) scores. Negative scores indicate an anti-inflammatory diet and positive scores indicates a pro-inflammatory diet. The sample was divided according to whether individuals increased or decreased E-DII scores after therapy.

Results: After therapy the body mass index (BMI), body weight, body fat, abdominal, waist, neck, and hip circumferences decreased significantly. The mean of high-density lipoprotein cholesterol (HDL-c) increased after the therapy. There was found an improvement of inflammatory and cardiometabolic parameters. In exploratory analyses, this occurred mainly when the EDII improved.

Conclusion: Long-term interdisciplinary therapy combined with a health education website improved inflammatory serum markers in obese adolescents. Reduction in DII scores was associated with reduction of cardiometabolic parameters, suggesting that an anti-inflammatory diet may be an effective strategy to prevent and treat obesity and related comorbidities.

Trial:http://www.ensaiosclinicos.gov.br/rg/RBR-6txv3v/, Register Number: RBR-6txv3v

Making sense of gut feelings in the traumatic brain injury pathogenesis

Traumatic brain injury (TBI) is a devastating condition which often initiates a sequel of neurological disorders that can last throughout lifespan. From metabolic perspective, TBI also compromises systemic physiology including the function of body organs with subsequent malfunctions in metabolism. The emerging panorama is that the effects of TBI on the periphery strike back on the brain and exacerbate the overall TBI pathogenesis. An increasing number of clinical reports are alarming to show that metabolic dysfunction is associated with incidence of long-term neurological and psychiatric disorders. The autonomic nervous system, associated hypothalamic-pituitary axis, and the immune system are at the center of the interface between brain and body and are central to the regulation of overall homeostasis and disease. We review the strong association between mechanisms that regulate cell metabolism and inflammation which has important clinical implications for the communication between body and brain. We also discuss the integrative actions of lifestyle interventions such as diet and exercise on promoting brain and body health and cognition after TBI.

Synthesis of deuterium-labelled amlexanox and its metabolic stability against mouse, rat, and human microsomes

As part of a program toward making analogues of amlexanox (1), currently under clinical investigation for the treatment of type 2 diabetes and obesity, we have synthesized derivative 5 in which deuterium has been introduced into two sites of metabolism on the C-7 isopropyl function of amlexanox. The synthesis of 5 was completed in an efficient three-step process utilizing reduction of key olefin 7b to 8 by Wilkinson's catalyst to provide specific incorporation of di-deuterium across the double bond. Compound 5 displayed nearly equivalent potency to amlexanox (IC₅₀ , 1.1μM vs 0.6μM, respectively) against recombinant human TBK1. When incubated with human, rat, and mouse liver microsomes, amlexanox (1) and d₂ -amlexanox (5) were stable (t_1/2  > 60 minutes) with 1 showing marginally greater stability relative to 5 except for rat liver microsomes. These data show that incorporating deuterium into two sites of metabolism does not majorly suppress Cyp-mediated metabolism relative to amlexanox.

Adipose Tissue Dysfunction as Determinant of Obesity-Associated Metabolic Complications

Obesity is a critical risk factor for the development of type 2 diabetes (T2D), and its prevalence is rising worldwide. White adipose tissue (WAT) has a crucial role in regulating systemic energy homeostasis. Adipose tissue expands by a combination of an increase in adipocyte size (hypertrophy) and number (hyperplasia). The recruitment and differentiation of adipose precursor cells in the subcutaneous adipose tissue (SAT), rather than merely inflating the cells, would be protective from the obesity-associated metabolic complications. In metabolically unhealthy obesity, the storage capacity of SAT, the largest WAT depot, is limited, and further caloric overload leads to the fat accumulation in ectopic tissues (e.g., liver, skeletal muscle, and heart) and in the visceral adipose depots, an event commonly defined as “lipotoxicity.” Excessive ectopic lipid accumulation leads to local inflammation and insulin resistance (IR). Indeed, overnutrition triggers uncontrolled inflammatory responses in WAT, leading to chronic low-grade inflammation, therefore fostering the progression of IR. This review summarizes the current knowledge on WAT dysfunction in obesity and its associated metabolic abnormalities, such as IR. A better understanding of the mechanisms regulating adipose tissue expansion in obesity is required for the development of future therapeutic approaches in obesity-associated metabolic complications.

Function and Mechanism of Long Noncoding RNAs in Adipocyte Biology

The last two decades have witnessed an explosion of interest in adipocyte biology, coinciding with the upsurge of obesity and metabolic syndrome. Now we have new perspectives on the distinct developmental origins of white, brown, and beige adipocytes and their role in metabolic physiology and disease. Beyond fuel metabolism, adipocytes communicate with the immune system and other tissues by releasing diverse paracrine and endocrine factors to orchestrate adipose tissue remodeling and maintain systemic homeostasis. Significant progress has been made in delineating the regulatory networks that govern different aspects of adipocyte biology. Here we provide an overview on the emerging role of long noncoding RNAs (lncRNAs) in the regulation of adipocyte development and metabolism and discuss the implications of the RNA-protein regulatory interface in metabolic control.

Gut microbial metabolites in obesity, NAFLD and T2DM

Evidence is accumulating that the gut microbiome is involved in the aetiology of obesity and obesity-related complications such as nonalcoholic fatty liver disease (NAFLD), insulin resistance and type 2 diabetes mellitus (T2DM). The gut microbiota is able to ferment indigestible carbohydrates (for example, dietary fibre), thereby yielding important metabolites such as short-chain fatty acids and succinate. Numerous animal studies and a handful of human studies suggest a beneficial role of these metabolites in the prevention and treatment of obesity and its comorbidities. Interestingly, the more distal colonic microbiota primarily ferments peptides and proteins, as availability of fermentable fibre, the major energy source for the microbiota, is limited here. This proteolytic fermentation yields mainly harmful products such as ammonia, phenols and branched-chain fatty acids, which might be detrimental for host gut and metabolic health. Therefore, a switch from proteolytic to saccharolytic fermentation could be of major interest for the prevention and/or treatment of metabolic diseases. This Review focuses on the role of products derived from microbial carbohydrate and protein fermentation in relation to obesity and obesity-associated insulin resistance, T2DM and NAFLD, and discusses the mechanisms involved.

Body Fat Percentage, Waist Circumference, and Obesity As Risk Factors for Rheumatoid Arthritis: A Danish Cohort Study

OBJECTIVE

To investigate the relationship between bioimpedance-derived total body fat percentage, waist circumference, and body mass index (BMI) and the subsequent development of rheumatoid arthritis (RA).

METHODS

A population-based prospective cohort study was conducted using 55,037 patients enrolled in the Danish Diet, Cancer, and Health cohort. Baseline data included anthropometric measures and lifestyle factors. Individuals who developed RA were identified through linkage with the Danish National Patient Registry. The relationships between bioimpedance-derived body fat percentage, waist circumference, and BMI and incident RA were assessed using Cox proportional hazards regression models, stratifying by sex. All analyses were performed for overall RA and the serologic subtypes seropositive and other RA.

RESULTS

A total of 210 men (37.6% with seropositive RA) and 456 women (41.0% with seropositive RA) developed RA during a median follow-up of 20.1 years. In women, the overall RA risk was 10% higher for each 5% increment of total body fat (hazard ratio [HR] 1.10 [95% confidence interval (95% CI) 1.02-1.18]), 5% higher for each 5-cm increment of waist circumference (HR 1.05 [95% CI 1.01-1.10]), and nearly 50% higher in those whose BMI was in the obese range compared to normal range BMI (HR 1.46 [95% CI 1.12-1.90]). These positive associations were also found for patients with other RA. In men, there were no clear associations between body fat percentage, waist circumference, or BMI and RA. No significant associations were found for seropositive RA in women or men, possibly related to low sample size.

CONCLUSION

In women, higher body fat percentage, higher waist circumference, and obesity were associated with a higher risk of RA.

Central role of Yes-associated protein and WW-domain-containing transcriptional co-activator with PDZ-binding motif in pancreatic cancer development

Pancreatic ductal adenocarcinoma (PDAC) remains a deadly disease with no efficacious treatment options. PDAC incidence is projected to increase, which may be caused at least partially by the obesity epidemic. Significantly enhanced efforts to prevent or intercept this cancer are clearly warranted. Oncogenic KRAS mutations are recognized initiating events in PDAC development, however, they are not entirely sufficient for the development of fully invasive PDAC. Additional genetic alterations and/or environmental, nutritional, and metabolic signals, as present in obesity, type-2 diabetes mellitus, and inflammation, are required for full PDAC formation. We hypothesize that oncogenic KRAS increases the intensity and duration of the growth-promoting signaling network. Recent exciting studies from different laboratories indicate that the activity of the transcriptional co-activators Yes-associated protein (YAP) and WW-domain-containing transcriptional co-activator with PDZ-binding motif (TAZ) play a critical role in the promotion and maintenance of PDAC operating as key downstream target of KRAS signaling. While initially thought to be primarily an effector of the tumor-suppressive Hippo pathway, more recent studies revealed that YAP/TAZ subcellular localization and co-transcriptional activity is regulated by multiple upstream signals. Overall, YAP has emerged as a central node of transcriptional convergence in growth-promoting signaling in PDAC cells. Indeed, YAP expression is an independent unfavorable prognostic marker for overall survival of PDAC. In what follows, we will review studies implicating YAP/TAZ in pancreatic cancer development and consider different approaches to target these transcriptional regulators.

Low muscle mass and strength in pediatrics patients: Why should we care?

Skeletal muscle plays major roles in metabolism and overall health across the lifecycle. Emerging evidence indicates that prenatal (maternal diet during pregnancy and genetic defects) and postnatal factors (physical activity, hormones, dietary protein, and obesity) influence muscle mass acquisition and strength early in life. As a consequence, low muscle mass and strength contributes to several adverse health outcomes during childhood. Specifically, studies demonstrated inverse associations of muscle mass and strength to single and clustered metabolic risk factors. The literature also consistently reports that low muscle mass and strength are associated with reduced bone parameters during growth, increasing the risk of osteoporosis in old age. Furthermore, muscle mass gains are associated with improved neurodevelopment in the first years of life. Given these negative implications of low muscle mass and strength on health, it is crucial to track muscle mass and strength development from childhood to adolescence. Several body composition techniques are currently available for estimation of muscle mass, all with unique advantages and disadvantages. The value of ultrasound as a technique to measure muscle mass is emerging in pediatric research with potential for translating the research findings to clinical settings. For the assessment of muscle strength, the handgrip strength test has been widely employed but without a standardized protocol. Although further research is needed to define normative data and cut points for the low muscle mass and strength phenotype, the use of such non-invasive medical monitoring is a promising strategy to identify early abnormalities and prevent low muscle mass in adulthood.

The Potential Role of Probiotics in Controlling Overweight/Obesity and Associated Metabolic Parameters in Adults: A Systematic Review and Meta-Analysis

Background

The prevalence of overweight/obesity in adults is raised to 39%, which is nearly tripled more than 1975. The alteration of the gut microbiome has been widely accepted as one of the main causal factors. To find an effective strategy for the prevention and treatment of overweight/obesity, a systematic review and meta-analysis were designed.

Methods

In this study, we systematically reviewed the article published from January 2008 to July 2018 and conducted a meta-analysis to examine the effects of probiotics on body weight control, lipid profile, and glycemic control in healthy adults with overweight or obesity. The primary outcomes were body weight, body mass index (BMI), waist circumference, fat mass, fat percentages, plasma lipid profiles, and glucose metabolic parameters.

Results

We systematically searched PubMed, Embase, and the Web of Science and identified 1248 articles, and 7 articles which were manually searched by the references of included studies and previously systematic reviews. Twelve randomized controlled trials (RCTs), including 821 participants, were included in the meta-analysis via full-text screening. Probiotics supplementation resulted in a statistical reduction in body weight (WMD [95% CI]; -0.55 [-0.91, -0.19] kg), BMI (WMD [95% CI]; -0.30 [-0.43, -0.18] kg m⁻²), waist circumference (WMD [95% CI]; -1.20 [-2.21, -0.19] cm), fat mass (WMD [95% CI]; -0.91 [-1.19, -0.63] kg), and fat percentage (WMD [95% CI]; -0.92 [-1.27, -0.56] %) compared with control groups. As expected, the metabolic parameters were improved significantly, with a pooled standardized mean difference in TC (SMD [95% CI]; -0.43 [-0.80, -0.07]), LDL-C (SMD [95% CI]; -0.41 [-0.77, -0.04]), FPG (SMD [95% CI]; -0.35 [-0.67, -0.02]), insulin (SMD [95% CI]; -0.44 [-0.84, -0.03]), and HOMA-IR (SMD [95% CI]; -0.51 [-0.96, -0.05]), respectively. The changes in TG (SMD [95% CI]; 0.14 [-0.23, 0.50]), HDL-C (SMD [95% CI]; -0.31 [-0.70, 0.07]), and HbA1c (SMD [95% CI]; -0.23 [-0.46, 0.01]) were not significant.

Conclusion

This study suggests that the probiotics supplementation could potentially reduce the weight gain and improve some of the associated metabolic parameters, which may become an effective strategy for the prevention and treatment of obesity in adult individuals.

Links between Immunologic Memory and Metabolic Cycling

Treatments for metabolic diseases, such as diet and therapeutics, often provide short-term therapy for metabolic stressors, but relapse is common. Repeated bouts of exposure to, and relief from, metabolic stimuli results in a phenomenon we call "metabolic cycling." Recent human and rodent data suggest metabolic cycling promotes an exaggerated response and ultimately worsened metabolic health. This is particularly evident with cycling of body weight and hypertension. The innate and adaptive immune systems have a profound impact on development of metabolic disease, and current data suggest that immunologic memory may partially explain this association, especially in the context of metabolic cycling. In this Brief Review, we highlight recent work in this field and discuss potential immunologic mechanisms for worsened disease prognosis in individuals who experience metabolic cycling.

GLP-1 Limits Adipocyte Inflammation and Its Low Circulating Pre-Operative Concentrations Predict Worse Type 2 Diabetes Remission after Bariatric Surgery in Obese Patients

OBJECTIVE

Glucagon-like peptide (GLP)-1 has been proposed as a key candidate in glucose improvements after bariatric surgery. Our aim was to explore the role of GLP-1 in surgically-induced type 2 diabetes (T2D) improvement and its capacity to regulate human adipocyte inflammation.

METHODS

Basal circulating concentrations of GLP-1 as well as during an oral glucose tolerance test (OGTT) were measured in lean and obese volunteers with and without T2D (n = 93). In addition, GLP-1 levels were determined before and after weight loss achieved by Roux-en-Y gastric bypass (RYGB) (n = 77). The impact of GLP-1 on inflammation signalling pathways was also evaluated.

RESULTS

We show that the reduced (p < 0.05) circulating levels of GLP-1 in obese T2D patients increased (p < 0.05) after RYGB. The area under the curve was significantly lower in obese patients with (p < 0.01) and without (p < 0.05) T2D compared to lean volunteers while obese patients with T2D exhibited decreased GLP-1 levels at baseline (p < 0.05) and 120 min (p < 0.01) after the OGTT. Importantly, higher (p < 0.05) pre-operative GLP-1 concentrations were found in patients with T2D remission after RYGB. We also revealed that exendin-4, a GLP-1 agonist, downregulated the expression of inflammation-related genes (IL1B, IL6, IL8, TNF) and, conversely, upregulated the mRNA levels of ADIPOQ in human visceral adipocytes. Furthermore, exendin-4 blocked (p < 0.05) LPS-induced inflammation in human adipocytes via downregulating the expression and secretion of key inflammatory markers.

CONCLUSIONS

Our data indicate that GLP-1 may contribute to glycemic control and exert a role in T2D remission after RYGB. GLP-1 is also involved in limiting inflammation in human visceral adipocytes.

Molecular pathways linking adipose innervation to insulin action in obesity and diabetes mellitus

Adipose tissue comprises adipocytes and many other cell types that engage in dynamic crosstalk in a highly innervated and vascularized tissue matrix. Although adipose tissue has been studied for decades, it has been appreciated only in the past 5 years that extensive arborization of nerve fibres has a dominant role in regulating the function of adipose tissue. This Review summarizes the latest literature, which suggests that adipocytes signal to local sensory nerve fibres in response to perturbations in lipolysis and lipogenesis. Such adipocyte signalling to the central nervous system causes sympathetic output to distant adipose depots and potentially other metabolic tissues to regulate systemic glucose homeostasis. Paracrine factors identified in the past few years that mediate such adipocyte-neuron crosstalk are also reviewed. Similarly, immune cells and endothelial cells within adipose tissue communicate with local nerve fibres to modulate neurotransmitter tone, blood flow, adipocyte differentiation and energy expenditure, including adipose browning to produce heat. This understudied field of neurometabolism related to adipose tissue biology has great potential to reveal new mechanistic insights and potential therapeutic strategies for obesity and type 2 diabetes mellitus.

Association between Irisin, hs-CRP, and Metabolic Status in Children and Adolescents with Type 2 Diabetes Mellitus

Proinflammatory cytokines and the novel myokine irisin, a cleavage product of FNDC5, have been found to play a role in obesity and type 2 diabetes mellitus (T2DM). Irisin has been shown to increase browning of adipose tissue, thermogenesis, energy expenditure, and insulin sensitivity, yet its association with inflammatory markers is still limited. Circulating irisin has been found to be increased in obesity, while in adult subjects with T2DM decreased levels have been found. However, data establishing the association of circulating irisin in children and adolescents with T2DM has not been described in the literature. The objective of this study was to determine irisin plasma concentration and its association with metabolic and adiposity markers and with hs-CRP, a surrogate marker of inflammation used in clinical practice, in a pediatric population with T2DM. A cross-sample of 40 Mexican children and adolescents aged 7-17 were recruited, 20 diagnosed with T2DM and 20 healthy controls. Plasma irisin levels were found to be lower in the T2DM group compared with controls, which could be attributed to a reduced PGC-1α activity in muscle tissue with a consequent decrease in FNDC5 and irisin expression. Irisin concentration was found to be positively correlated with HDL-c, LDL-c, and total cholesterol, while negatively correlated with BMI, waist circumference, and triglycerides. However, after multiple regression analysis, only HDL-c correlation remained significant. hs-CRP was higher in the T2DM group and positively associated with adiposity markers, unfavorable lipid profile, insulin levels, and HOMA-IR, but no association with irisin was found. Given the favorable metabolic effects attributed to irisin, the low plasma levels found in children and adolescents with T2DM could exacerbate the inflammatory and metabolic imbalances and the intrinsic cardiovascular risk of this disease. We propose an "irisin-proinflammatory/anti-inflammatory axis" to explain the role of irisin as a metabolic regulator in obesity and T2DM.

Association between body mass index and response to duloxetine for aromatase inhibitor-associated musculoskeletal symptoms in SWOG S1202

BACKGROUND

Aromatase inhibitor (AI)-associated musculoskeletal symptoms (AIMSS) negatively impact adherence to and persistence with therapy. In SWOG S1202, patients with AIMSS who were treated with duloxetine, a serotonin norepinephrine reuptake inhibitor, reported improvement in pain by 12 weeks compared with placebo. Based on the authors' prior observation that responses to pain interventions differ between obese and nonobese patients, the current study examined whether response to duloxetine therapy differed by obesity status.

METHODS

In SWOG S1202, a total of 299 AI-treated postmenopausal women with stage I to III (AJCC 7th Edition) breast cancer who developed new or worsening average pain were enrolled, randomized to duloxetine or placebo, and treated for 12 weeks. Patient-reported outcomes were obtained at baseline and through 12 weeks. Patients were categorized into nonobese (body mass index [BMI] <30 kg/m² ) or obese (BMI ≥30 kg/m² ). The authors tested the interaction between intervention and obesity with respect to average pain at 12 weeks in the 289 eligible patients, using a P value of .05 to indicate statistical significance.

RESULTS

In approximately 54% of evaluable patients with a BMI ≥30 kg/m² , the reduction in the mean average pain score between baseline and 12 weeks was statistically significantly greater for patients treated with duloxetine compared with those receiving placebo (-2.73 vs -1.64 points; P = .003). Conversely, in the nonobese patients, the reduction in the mean average pain score was similar in the 2 cohorts (-2.46 vs -2.34 points; P = .75). The P value for interaction was .02, thereby meeting the threshold criteria of the current study. Similar findings were evident for other pain-related patient-reported outcomes.

CONCLUSIONS

In this trial, obese patients with AIMSS obtained more analgesic benefit from duloxetine compared with nonobese patients. Additional studies are warranted to determine the biologic basis for these findings.

Fibroblast Growth Factor 21 Exerts its Anti-inflammatory Effects on Multiple Cell Types of Adipose Tissue in Obesity

OBJECTIVE

Obesity-related, chronic, low-grade inflammation has been identified as a key factor in the development of many metabolic diseases, such as type 2 diabetes and cardiovascular diseases. Adipocytes, preadipocytes, and macrophages have been implicated in initiating inflammation in adipose tissue. This study aims to investigate the effects of fibroblast growth factor-21 (FGF-21) on obesity-related inflammation and its mechanisms in vivo and in vitro.

METHODS

Monosodium glutamate (MSG) was used to induce obesity in mice and subsequently treated the mice with or without FGF-21. Primary adipocytes and stromal vascular fraction cells were isolated from MSG-obesity mice for additional experiments.

RESULTS

Results obtained by ELISA and real-time polymerase chain reaction showed that FGF-21 efficiently ameliorated obesity-related inflammation in MSG-obesity mice. This study demonstrated that preadipocytes and adipocytes responded to anti-inflammatory effects of FGF-21. In vitro, 3 T3-L1 preadipocytes lacking β-klotho did not respond to FGF-21 under glucose uptake. Interestingly, the treatment of 3 T3-L1 preadipocytes with FGF-21 significantly attenuated lipopolysaccharide-induced inflammatory response.

CONCLUSIONS

Our study showed that FGF-21-induced glucose uptake and FGF-21-related anti-inflammatory effects are mediated by different signaling pathways. Moreover, FGF-21 showed anti-inflammatory effects on preadipocytes; these effects are mediated by the fibroblast growth factor receptor substrate 2/ERK1/2 signaling pathway.

Mechanisms of obesity-induced metabolic and vascular dysfunctions

Obesity has reached epidemic proportions and its prevalence is climbing. Obesity is characterized by hypertrophied adipocytes with a dysregulated adipokine secretion profile, increased recruitment of inflammatory cells, and impaired metabolic homeostasis that eventually results in the development of systemic insulin resistance, a phenotype of type 2 diabetes. Nitric oxide synthase (NOS) is an enzyme that converts L-arginine to nitric oxide (NO), which functions to maintain vascular and adipocyte homeostasis. Arginase is a ureohydrolase enzyme that competes with NOS for L-arginine. Arginase activity/expression is upregulated in obesity, which results in diminished bioavailability of NO, impairing both adipocyte and vascular endothelial cell function. Given the emerging role of NO in the regulation of adipocyte physiology and metabolic capacity, this review explores the interplay between arginase and NO, and their effect on the development of metabolic disorders, cardiovascular diseases, and mitochondrial dysfunction in obesity. A comprehensive understanding of the mechanisms involved in the development of obesity-induced metabolic and vascular dysfunction is necessary for the identification of more effective and tailored therapeutic avenues for their prevention and treatment.

The obese adipose tissue microenvironment in cancer development and progression

Obesity is associated with both increased cancer incidence and progression in multiple tumour types, and is estimated to contribute to up to 20% of cancer-related deaths. These associations are driven, in part, by metabolic and inflammatory changes in adipose tissue that disrupt physiological homeostasis both within local tissues and systemically. However, the mechanisms underlying the obesity-cancer relationship are poorly understood. In this Review, we describe how the adipose tissue microenvironment (ATME) evolves during body-weight gain, and how these changes might influence tumour initiation and progression. We focus on multiple facets of ATME physiology, including inflammation, vascularity and fibrosis, and discuss therapeutic interventions that have the potential to normalize the ATME, which might be translationally relevant for cancer prevention and therapy. Given that the prevalence of obesity is increasing on an international scale, translational research initiatives are urgently needed to provide mechanistic explanations for the obesity-cancer relationship, and how to best identify high-risk individuals without relying on crude measures, such as BMI.

Metabolic Disease Epidemics: Emerging Challenges in Regenerative Medicine

The interplay between cell/tissue damage caused by metabolic dysfunction and regenerative potential remains elusive. The tissue engineering and regenerative medicine (TERM) field is now facing a worldwide epidemic of obesity. This Forum article uncovers prospective questions to be addressed in TERM toward the development of effective regenerative therapies adjusted to these new demands.

Predictors of mitochondrial DNA copy number and damage in a mercury-exposed rural Peruvian population near artisanal and small-scale gold mining: An exploratory study

Mitochondrial DNA (mtDNA) copy number (CN) and damage in circulating white blood cells have been proposed as effect biomarkers for pollutant exposures. Studies have shown that mercury accumulates in mitochondria and affects mitochondrial function and integrity; however, these data are derived largely from experiments in model systems, rather than human population studies that evaluate the potential utility of mitochondrial exposure biomarkers. We measured mtDNA CN and damage in white blood cells (WBCs) from 83 residents of nine communities in the Madre de Dios region of the Peruvian Amazon that vary in proximity to artisanal and small-scale gold mining. Prior research from this region reported high levels of mercury in fish and a significant association between food consumption and human total hair mercury level of residents. We observed that mtDNA CN and damage were both associated with consumption of fruit and vegetables, higher diversity of fruit consumed, residential location, and health characteristics, suggesting common environmental drivers. Surprisingly, we observed negative associations of mtDNA damage with both obesity and age. We did not observe any association between total hair mercury or, in contrast to previous results, age, with either mtDNA damage or CN. The results of this exploratory study highlight the importance of combining epidemiological and laboratory research in studying the effects of stressors on mitochondria, suggesting that future work should incorporate nutritional and social characteristics, and caution should be taken when applying conclusions from epidemiological studies conducted in the developed world to other regions, as results may not be easily translated. Environ. Mol. Mutagen. 60: 197-210, 2019. © 2018 Wiley Periodicals, Inc.

Looking on the "brite" side exercise-induced browning of white adipose tissue

The need for effective and convenient ways of combatting obesity has created great interest in brown adipose tissue (BAT). However, because adult humans have relatively little amounts of BAT, the possibility of browning white adipose tissue (WAT), i.e., switching the metabolism of WAT from an energy storing to energy burning organ, has gained considerable attention. Exercise has countless health benefits, and has consistently been shown to cause browning in rodent white adipose tissue. The purpose of this review is to provide an overview of recent studies examining the effects of exercise and other interventions on the browning of white adipose tissue. The role of various endocrine factors, including catecholamines, interleukin-6, irisin, and meteorin-like in addition to local re-esterification-mediated mechanisms in inducing the browning of WAT will be discussed. The physiological importance of browning will be discussed, as will discrepancies in the literature between human and rodent studies.

Macrophages in obesity and non-alcoholic fatty liver disease: Crosstalk with metabolism

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disease worldwide, and a major cause of liver cirrhosis and hepatocellular carcinoma. NAFLD is intimately linked with other metabolic disorders characterized by insulin resistance. Metabolic diseases are driven by chronic inflammatory processes, in which macrophages perform essential roles. The polarization status of macrophages is itself influenced by metabolic stimuli such as fatty acids, which in turn affect the progression of metabolic dysfunction at multiple disease stages and in various tissues. For instance, adipose tissue macrophages respond to obesity, adipocyte stress and dietary factors by a specific metabolic and inflammatory programme that stimulates disease progression locally and in the liver. Kupffer cells and monocyte-derived macrophages represent ontologically distinct hepatic macrophage populations that perform a range of metabolic functions. These macrophages integrate signals from the gut-liver axis (related to dysbiosis, reduced intestinal barrier integrity, endotoxemia), from overnutrition, from systemic low-grade inflammation and from the local environment of a steatotic liver. This makes them central players in the progression of NAFLD to steatohepatitis (non-alcoholic steatohepatitis or NASH) and fibrosis. Moreover, the particular involvement of Kupffer cells in lipid metabolism, as well as the inflammatory activation of hepatic macrophages, may pathogenically link NAFLD/NASH and cardiovascular disease. In this review, we highlight the polarization, classification and function of macrophage subsets and their interaction with metabolic cues in the pathophysiology of obesity and NAFLD. Evidence from animal and clinical studies suggests that macrophage targeting may improve the course of NAFLD and related metabolic disorders.

The pseudokinase MLKL regulates hepatic insulin sensitivity independently of inflammation

Objective

The mixed lineage kinase domain like (MLKL) protein, receptor interacting protein (RIPK) 1, and RIPK3 are key regulators of necroptosis, a highly pro-inflammatory mode of cell death that has been implicated in various pathological processes and human diseases. However, the role of these necroptotic regulators in diabetes remains unknown. Here we sought to delineate the role of MLKL in insulin resistance and type 2 diabetes (T2D).

Methods

We first analyzed the expression of key necroptotic regulators in obese/diabetic mouse models. We then utilized MLKL knockout (MLKL^−/−) mice to evaluate the effects of MLKL on obesity-induced metabolic complications. We further determined the consequences of MLKL inhibition on hepatic insulin signaling and explored the underlying mechanism. Finally, we assessed the potential therapeutic effects of necroptotic inhibitor, necrostatin-1 (Nec-1), in ob/ob mice.

Results

In wild-type or obese mice (ob/ob, db/db, or diet-induced obesity), MLKL was increased in certain obesity-associated tissues, particularly in the liver. Whole-body deficiency of MLKL prevented obesity-induced insulin resistance and glucose intolerance. Inhibition of MLKL or other key necroptotic regulators enhanced hepatic insulin sensitivity. MLKL modulated insulin-stimulated PI(3,4,5)P3 production in liver cells but did not affect the expression of inflammatory genes in vitro and in vivo. Nec-1 administration ameliorated insulin resistance and glucose intolerance in ob/ob mice.

Conclusions

These findings reveal MLKL as a regulator of insulin sensitivity and suggest necroptotic regulators might be potential therapeutic targets for insulin resistance and T2D.

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Hepatic MLKL is increased in diabetic mouse models.

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MLKL deficiency prevents obesity-induced metabolic complications.

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Inhibition of MLKL enhances insulin sensitivity independent of inflammation.

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Pharmacological inhibition of RIPK1 in ob/ob mice ameliorates insulin resistance.

Essential Roles for the Non-Canonical IκB Kinases in Linking Inflammation to Cancer, Obesity, and Diabetes

Non-canonical IκB kinases (IKKs) TBK1 and IKKε have essential roles as regulators of innate immunity and cancer. Recent work has also implicated these kinases in distinctively controlling glucose homeostasis and repressing adaptive thermogenic and mitochondrial biogenic response upon obesity-induced inflammation. Additionally, TBK1 and IKKε regulate pancreatic β-cell regeneration. In this review, we summarize current data on the functions and molecular mechanisms of TBK1 and IKKε in orchestrating inflammation to cancer, obesity, and diabetes.

Liver-specific insulin receptor isoform A expression enhances hepatic glucose uptake and ameliorates liver steatosis in a mouse model of diet-induced obesity

Among the main complications associated with obesity are insulin resistance and altered glucose and lipid metabolism within the liver. It has previously been described that insulin receptor isoform A (IRA) favors glucose uptake and glycogen storage in hepatocytes compared with isoform B (IRB), improving glucose homeostasis in mice lacking liver insulin receptor. Thus, we hypothesized that IRA could also improve glucose and lipid metabolism in a mouse model of high-fat-diet-induced obesity. We addressed the role of insulin receptor isoforms in glucose and lipid metabolism in vivo. We expressed IRA or IRB specifically in the liver by using adeno-associated viruses (AAVs) in a mouse model of diet-induced insulin resistance and obesity. IRA, but not IRB, expression induced increased glucose uptake in the liver and muscle, improving insulin tolerance. Regarding lipid metabolism, we found that AAV-mediated IRA expression also ameliorated hepatic steatosis by decreasing the expression of Fasn, Pgc1a, Acaca and Dgat2 and increasing Scd-1 expression. Taken together, our results further unravel the role of insulin receptor isoforms in hepatic glucose and lipid metabolism in an insulin-resistant scenario. Our data strongly suggest that IRA is more efficient than IRB at favoring hepatic glucose uptake, improving insulin tolerance and ameliorating hepatic steatosis. Therefore, we conclude that a gene therapy approach for hepatic IRA expression could be a safe and promising tool for the regulation of hepatic glucose consumption and lipid metabolism, two key processes in the development of non-alcoholic fatty liver disease associated with obesity.

This article has an associated First Person interview with the first author of the paper.

Summary: Adeno-associated-virus-mediated gene therapy for insulin receptor isoform A expression in the liver improves glucose disposal and alleviates lipid accumulation in wild-type mice under a high-fat diet.

The hepatokine Tsukushi gates energy expenditure via brown fat sympathetic innervation

Thermogenesis is an important contributor to whole body energy expenditure and metabolic homeostasis. Although circulating factors that promote energy expenditure are known, endocrine molecules that suppress energy expenditure have remained largely elusive. Here we show that Tsukushi (TSK) is a liver-enriched secreted factor that is highly inducible in response to increased energy expenditure. Hepatic Tsk expression and plasma TSK levels are elevated in obesity. TSK deficiency increases sympathetic innervation and norepinephrine release in adipose tissue, leading to enhanced adrenergic signaling and thermogenesis, attenuation of brown fat whitening and protection from diet-induced obesity in mice. Our work reveals TSK as part of a negative feedback mechanism that gates thermogenic energy expenditure and highlights TSK as a potential target for therapeutic intervention in metabolic disease.

Comprehensive and quantitative analysis of white and brown adipose tissue by shotgun lipidomics

Objective

Shotgun lipidomics enables an extensive analysis of lipids from tissues and fluids. Each specimen requires appropriate extraction and processing procedures to ensure good coverage and reproducible quantification of the lipidome. Adipose tissue (AT) has become a research focus with regard to its involvement in obesity-related pathologies. However, the quantification of the AT lipidome is particularly challenging due to the predominance of triacylglycerides, which elicit high ion suppression of the remaining lipid classes.

Methods

We present a new and validated method for shotgun lipidomics of AT, which tailors the lipid extraction procedure to the target specimen and features high reproducibility with a linear dynamic range of at least 4 orders of magnitude for all lipid classes.

Results

Utilizing this method, we observed tissue-specific and diet-related differences in three AT types (brown, gonadal, inguinal subcutaneous) from lean and obese mice. Brown AT exhibited a distinct lipidomic profile with the greatest lipid class diversity and responded to high-fat diet by altering its lipid composition, which shifted towards that of white AT. Moreover, diet-induced obesity promoted an overall remodeling of the lipidome, where all three AT types featured a significant increase in longer and more unsaturated triacylglyceride and phospholipid species.

Conclusions

The here presented method facilitates reproducible systematic lipidomic profiling of AT and could be integrated with further –omics approaches used in (pre-) clinical research, in order to advance the understanding of the molecular metabolic dynamics involved in the pathogenesis of obesity-associated disorders.

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Validated shotgun lipidomics method of AT covering 300 lipids of 20 classes and linear dynamic range of 4 orders of magnitude.

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Increase of longer and more unsaturated triacylglycerides and phospholipids in brown and white AT under high-fat diet.

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Differences in the lipidomes of gonadal, subcutaneous and brown AT.

Mediation of associations between adiposity and colorectal cancer risk by inflammatory and metabolic biomarkers

Inflammation and hyperinsulinemia may drive associations between adiposity and colorectal cancer (CRC) risk, but few studies have examined this hypothesis using mediation analysis. We used inverse odds ratio weighting and logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI) for estimated total effects (OR^TE ) of body mass index, waist circumference, and adult weight gain on CRC risk, and estimated effects operating through seven inflammatory and metabolic biomarkers (natural indirect effect; OR^NIE ) or through paths independent of these biomarkers (natural direct effect; OR^NDE ) among 209 CRC cases and 382 matched controls nested within the Health Professionals Follow-up Study, a prospective cohort of male health professionals. A one-interquartile range (IQR) increase in body mass index (3.6 kg/m² ) was associated with an OR^TE of 1.40 (95% CI: 1.13, 1.73), which decomposed into an OR^NIE of 1.26 (95% CI: 0.97, 1.52) and an OR^NDE of 1.11 (0.87, 1.42), with possibly stronger mediation by these biomarkers for adult weight gain (IQR = 10.4 kg; OR^TE = 1.32 [95% CI: 1.06, 1.64]; OR^NIE = 1.47 [95% CI: 1.01, 1.81]; OR^NDE = 0.89 [95% CI: 0.72, 1.11]), but no mediation for waist circumference. Mediation appeared to be stronger for the metabolic biomarkers than the inflammatory biomarkers. Inflammatory and metabolic mechanisms may mediate associations between both body mass index and adult weight gain with CRC risk.

Altered Adipose Tissue DNA Methylation Status in Metabolic Syndrome: Relationships Between Global DNA Methylation and Specific Methylation at Adipogenic, Lipid Metabolism and Inflammatory Candidate Genes and Metabolic Variables

Metabolic syndrome (MetS) has been postulated to increase the risk for type 2 diabetes, cardiovascular disease and cancer. Adipose tissue (AT) plays an important role in metabolic homeostasis, and AT dysfunction has an active role in metabolic diseases. MetS is closely related to lifestyle and environmental factors. Epigenetics has emerged as an interesting landscape to evaluate the possible interconnection between AT and metabolic disease, since it can be modulated by environmental factors and metabolic status. The aim of this study was to determine whether MetS has an impact on the global DNA methylation pattern and the DNA methylation of several genes related to adipogenesis (PPARG, PPARA), lipid metabolism (RXRA, SREBF2, SREBF1, SCD, LPL, LXRb), and inflammation (LRP1 C3, LEP and TNF) in visceral adipose tissue. LPL and TNF DNA methylation values were significantly different in the control-case comparisons, with higher and lower methylation respectively in the MetS group. Negative correlations were found between global DNA methylation (measured by LINE-1 methylation levels) and the metabolic deterioration and glucose levels. There were associations among variables of MetS, BMI, and HOMA-IR with DNA methylation at several CpG positions for the studied genes. In particular, there was a strong positive association between serum triglyceride levels (TG) with PPARA and LPL methylation levels. TNF methylation was negatively associated with the metabolic worsening and could be an important factor in preventing MetS occurrence according to logistic regression analysis. Therefore, global DNA methylation and methylation at specific genes related to adipogenesis, lipid metabolism and inflammation are related to the etiology of MetS and might explain in part some of the features associated to metabolic disorders.

The salivary levels of leptin and interleukin-6 as potential inflammatory markers in children obesity

Background

Obesity among children is an alarming issue due to an increased incidence over the last years with devastating physiological and psychological consequences. Current available medical diagnostic tools use invasive methods to evaluate and monitor the lipid profile, glycaemia or liver status for determining the overweight/ obesity complications. The standard methods proposed for the assay of IL6 and leptin from saliva cannot detect these two biomarkers in children saliva; the levels of IL6 and leptin in children’s saliva are lower than the limit of determination of the standard methods. Therefore, we proposed a method based on utilization of stochastic sensors, able to simultaneously perform a qualitative and quantitative determination of these two biomarkers within minutes, in the range able to cover healthy and obese children.

Methods

Children from the urban area monitored for annual standard analyses and health status assessment at National Institute of Endocrinology C.I. Parhon within University of Medicine and Pharmacy “Carol Davila”, Bucharest, Romania were included in the study. In the same day, for all participants of the study, blood analyses were performed and saliva samples were collected for the determination of the IL-6 and leptin levels.

Findings/ Results

The children diagnosed with overweight/ obesity presented not significantly different blood lipid profile and glycaemia comparing to the control group. Only few cases of the children presented high levels of cholesterol, low level of HDL-cholesterol, a slightly increased level of triglycerides and transaminases. No correlation with the body mass index could be established with the blood analyses results. In case of the overweight/obese children, the salivary level of the proinflammatory citokynes IL-6 (41ng/mL±21) and leptin (40.4ng/mL±28.8), were significantly increased comparing to normal weight children (IL-6 8.1±4.6, leptin 9.58±3.1). Moreover, the saliva level of the IL-6 was positively correlated with the body mass index. Salivary leptin level was highly variable in case of obese children, 6 patients presenting similar levels with the control group.

Conclusions

Increased levels of salivary IL-6 and leptin sustain a systemic inflammation status despite normal range of standard blood analyses. The results were positively correlated in case of IL-6 with the body mass index the general accepted method used for the assessment of the obesity or overweight degree The determination of these markers in saliva samples by a stochastic method proved the utility within the medical examination for a better evaluation of the health status in obesity. The method has some advantages like: easy collection of the biological sample, fast determination of low concentrations and could be promising in case of no associated oral cavity infections or inflammations which could interfere the results.

Biological Effects of Ciliary Neurotrophic Factor on hMADS Adipocytes

Administration of ciliary neurotrophic factor (CNTF) to experimental animals exerts anti-obesity effects by acting on multiple targets. In white adipose tissue CNTF reduces lipid content, promotes fatty acid (FA) oxidation and improves insulin sensitivity. This study was performed to establish whether CNTF exerts similar effects on human white adipocytes. To this end, adipose differentiation was induced in vitro in human multipotent adipose-derived stem (hMADS) cells. CNTF receptor α (CNTFRα) expression was assessed in hMADS cells and adipocytes by qRT-PCR, Western blotting, and immunocytochemistry. After administration of human recombinant CNTF, signaling pathways and gene expression were evaluated by Western blotting and qRT-PCR. Glucose uptake was assessed by measuring 2-nitrobenzodeoxyglucose uptake with a fluorescence plate reader. Lastly, CNTF-induced anti-inflammatory responses were evaluated in hMADS adipocytes stressed with tumor necrosis factor α (TNFα) for 24 h. Results showed that CNTFRα protein expression was higher in undifferentiated hMADS cells than in hMADS adipocytes, where it was however clearly detectable. In hMADS adipocytes, 1 nM CNTF strongly activated the JAK-STAT3 (Janus kinase-signaling transducer and activator of transcription 3) pathway and acutely and transiently activated the AMPK (AMP-activated protein kinase) and AKT (protein kinase B) pathways. Acute CNTF treatment for 20 min significantly increased basal glucose uptake and was associated with increased AKT phosphorylation. Longer-term (24 and 48 h) treatment reduced the expression of lipogenic markers (FA synthase and sterol regulatory element-binding protein-1) and increased the expression of lipolytic [hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL)] and mitochondrial (peroxisome proliferator-activated receptor γ coactivator-1α and carnitine palmitoyltransferase 1) markers. In TNFα-treated hMADS adipocytes, CNTF significantly reduced the expression of monocyte chemoattractant protein 1 and TNFα-induced AKT inhibition. Collectively, these findings demonstrate for the first time that CNTF plays a role also in human adipocytes, driving their metabolism toward a less lipid-storing and more energy-consuming phenotype.