Molecular evidence supporting the portal theory: a causative link between visceral adiposity and hepatic insulin resistance

Systems genetics analysis of human body fat distribution genes identifies adipocyte processes

Excess abdominal fat is a sexually dimorphic risk factor for cardio-metabolic disease and is approximated by the waist-to-hip ratio adjusted for body mass index (WHRadjBMI). Whereas this trait is highly heritable, few causal genes are known. We aimed to identify novel drivers of WHRadjBMI using systems genetics. We used two independent cohorts of adipose tissue gene expression and constructed sex- and depot-specific Bayesian networks to model gene-gene interactions from 8,492 genes. Using key driver analysis, we identified genes that, in silico and putatively in vitro, regulate many others. 51-119 key drivers in each network were replicated in both cohorts. In other cell types, 23 of these genes are found in crucial adipocyte pathways: Wnt signaling or mitochondrial function. We overexpressed or down-regulated seven key driver genes in human subcutaneous pre-adipocytes. Key driver genes ANAPC2 and RSPO1 inhibited adipogenesis, whereas PSME3 increased adipogenesis. RSPO1 increased Wnt signaling activity. In differentiated adipocytes, MIGA1 and UBR1 down-regulation led to mitochondrial dysfunction. These five genes regulate adipocyte function, and we hypothesize that they regulate fat distribution.

Prediction of Mortality and Hepatic Encephalopathy after Transjugular Intrahepatic Portosystemic Shunt Placement: Baseline and Longitudinal Body Composition Measurement

PURPOSE

To investigate effects of baseline and early longitudinal body composition changes on mortality and hepatic encephalopathy (HE) after transjugular intrahepatic portosystemic shunt (TIPS).

MATERIALS AND METHODS

This is a case-control study with analysis of a TIPS registry (1995-2020) including data from patients with cirrhosis with computed tomography (CT) scans obtained within 1 month before and 3 months after TIPS. Core muscle area (CMA), macroscopic subcutaneous adipose tissue (mSAT), macroscopic visceral adipose tissue (mVAT) area, and muscle adiposity index (MAI) on CT were obtained. Multipredictor Cox proportional hazards models were used to assess the effect of body composition variables on mortality or HE.

RESULTS

In total, 280 patients (158 men; median age, 57.0 years; median Model for End-stage Liver Disease-sodium [MELD-Na] score, 14.0) were included. Thirty-four patients had post-TIPS imaging. Median baseline CMA was 68.3 cm2 (interquartile range, 57.7-83.5 cm2). Patients with higher baseline CMA had decreased risks of mortality (hazard ratio [HR]: 0.82; P = .04) and HE (HR: 0.82; P = .009). It improved prediction of mortality over MELD-Na and post-TIPS right atrial pressure alone (confidence interval = 0.729). An increase in CMA (HR: 0.60; P = .043) and mSAT (HR: 0.86; P = .022) or decrease in MAI (HR: 1.50; P = .049) from before to after TIPS was associated with a decreased risk of mortality. An increase in mSAT was associated with an increased risk of HE (HR: 1.11; P = .04).

CONCLUSIONS

CMA on CT scan 1 month before TIPS placement predicts mortality and HE in patients with cirrhosis. Changes in body composition on CT measured 3 months after TIPS placement independently predict mortality and HE.

Visceral fat and cardiometabolic future in children and adolescents: a critical update

Cardiovascular disease (CVD) is a process whose pathogenetic mechanisms start very early in life. Recently, the importance of visceral adipose tissue (VAT) has been highlighted in the development of CVD. VAT does not always depend on body mass index (BMI) and has been implicated in unfavorable metabolic activity and cardiovascular adverse events. Abnormally high deposition of VAT is associated with metabolic syndrome, obesity-associated phenotype, and cardiometabolic risk factors. Although the importance of visceral fat has not been studied broadly or extensively in long-term studies in children and adolescents, it appears that it does not have the same behavior as in adults, it is related to the appearance of cardiac risk factors. In adolescents, it plays a role in the pathogenesis of CVD that occur later in adulthood. Excess body weight and adiposity may lead to the development of early myocardial and pathological coronary changes in childhood. The purpose of this review is to summarize the risk factors, the clinical significance, and the prognostic role of visceral obesity in children and adolescents. In addition, extensive reference is made to the most commonly used techniques for the evaluation of VAT in clinical settings. IMPACT: Visceral obesity, plays an important role in cardiovascular health from very early in an individual's life. Visceral adipose tissue (VAT) distribution is not entirely related to body mass index (BMI) and provides additional prognostic information. There is a need to pay more attention to the assessment of VAT in young people, to develop methods that would go beyond the measurement of only BMI in clinical practice and to identify individuals with excess visceral adiposity and perhaps to monitor its changes.

Systems genetics analysis of human body fat distribution genes identifies Wnt signaling and mitochondrial activity in adipocytes

BACKGROUND

Excess fat in the abdomen is a sexually dimorphic risk factor for cardio-metabolic disease. The relative storage between abdominal and lower-body subcutaneous adipose tissue depots is approximated by the waist-to-hip ratio adjusted for body mass index (WHRadjBMI). Genome-wide association studies (GWAS) identified 346 loci near 495 genes associated with WHRadjBMI. Most of these genes have unknown roles in fat distribution, but many are expressed and putatively act in adipose tissue. We aimed to identify novel sex- and depot-specific drivers of WHRadjBMI using a systems genetics approach.

METHODS

We used two independent cohorts of adipose tissue gene expression with 362 - 444 males and 147 - 219 females, primarily of European ancestry. We constructed sex- and depot- specific Bayesian networks to model the gene-gene interactions from 8,492 adipose tissue genes. Key driver analysis identified genes that, in silico and putatively in vitro, regulate many others, including the 495 WHRadjBMI GWAS genes. Key driver gene function was determined by perturbing their expression in human subcutaneous pre-adipocytes using lenti-virus or siRNA.

RESULTS

51 - 119 key drivers in each network were replicated in both cohorts. We used single-cell expression data to select replicated key drivers expressed in adipocyte precursors and mature adipocytes, prioritized genes which have not been previously studied in adipose tissue, and used public human and mouse data to nominate 53 novel key driver genes (10 - 21 from each network) that may regulate fat distribution by altering adipocyte function. In other cell types, 23 of these genes are found in crucial adipocyte pathways: Wnt signaling or mitochondrial function. We selected seven genes whose expression is highly correlated with WHRadjBMI to further study their effects on adipogenesis/Wnt signaling (ANAPC2, PSME3, RSPO1, TYRO3) or mitochondrial function (C1QTNF3, MIGA1, PSME3, UBR1).Adipogenesis was inhibited in cells overexpressing ANAPC2 and RSPO1 compared to controls. RSPO1 results are consistent with a positive correlation between gene expression in the subcutaneous depot and WHRadjBMI, therefore lower relative storage in the subcutaneous depot. RSPO1 inhibited adipogenesis by increasing β-catenin activation and Wnt-related transcription, thus repressing PPARG and CEBPA. PSME3 overexpression led to more adipogenesis than controls. In differentiated adipocytes, MIGA1 and UBR1 downregulation led to mitochondrial dysfunction, with lower oxygen consumption than controls; MIGA1 knockdown also lowered UCP1 expression.

SUMMARY

ANAPC2, MIGA1, PSME3, RSPO1, and UBR1 affect adipocyte function and may drive body fat distribution.

A Descriptive Review of the Action Mechanisms of Berberine, Quercetin and Silymarin on Insulin Resistance/Hyperinsulinemia and Cardiovascular Prevention

Insulin resistance (IR) and the associated hyperinsulinemia are early pathophysiological changes which, if not well treated, can lead to type 2 diabetes, endothelial dysfunction and cardiovascular disease. While diabetes care is fairly well standardized, the prevention and treatment of IR lacks a single pharmaceutical approach and many lifestyle and dietary interventions have been proposed, including a wide range of food supplements. Among the most interesting and well-known natural remedies, alkaloid berberine and the flavonol quercetin have particular relevance in the literature, while silymarin-the active principle of the Silybum marianum thistle-was traditionally used for lipid metabolism disorders and to sustain liver function. This review describes the major defects of insulin signaling leading to IR and the main properties of the three mentioned natural substances, their molecular targets and synergistic action mechanisms. The actions of berberine, quercetin and silymarin are partially superimposable as remedies against reactive oxygen intermediates generated by a high-lipid diet and by NADPH oxidase, which is triggered by phagocyte activation. Furthermore, these compounds inhibit the secretion of a battery of pro-inflammatory cytokines, modulate intestinal microbiota and are especially able to control the various disorders of the insulin receptor and post-receptor signaling systems. Although most of the evidence on the effects of berberine, quercetin and silymarin in modulating insulin resistance and preventing cardiovascular disease derive from experimental studies on animals, the amount of pre-clinical knowledge strongly suggests the need to investigate the therapeutic potential of these substances in human pathology.

Improved body composition decreases the fat content in non-alcoholic fatty liver disease, a meta-analysis and systematic review of longitudinal studies

Background

Based on cross-sectional studies, there is a link between body composition parameters and steatosis in non-alcoholic fatty liver disease (NAFLD). However, whether long-term changes in different body composition parameters will result in NAFLD resolution is unclear. Therefore, we aimed to summarize the literature on longitudinal studies evaluating the association between NAFLD resolution and body composition change.

Methods

Based on the recommendations of the Cochrane Handbook, we performed a systematic search on September 26th, 2021, in three databases: Embase, MEDLINE (via PubMed), and Cochrane Central Register of Controlled Trials (CENTRAL). Eligible studies reported on patients with NAFLD (liver fat >5%) and examined the correlation between body composition improvement and decrease in steatosis. We did not have pre-defined body composition or steatosis measurement criteria. Next, we calculated pooled correlation coefficient (r) with a 95% confidence interval (CI). Furthermore, we narratively summarized articles with other statistical methods.

Results

We included 15 studies in our narrative review and five in our quantitative synthesis. Based on two studies with 85 patients, we found a pooled correlation coefficient of r = 0.49 (CI: 0.22-0.69, Spearman's correlation) between the change of visceral adipose tissue and liver steatosis. Similarly, based on three studies with 175 patients, the correlation was r = 0.33 (CI: 0.19-0.46, Pearson's correlation). On the other hand, based on two studies with 163 patients, the correlation between subcutaneous adipose tissue change and liver steatosis change was r = 0.42 (CI: 0.29-0.54, Pearson's correlation). Furthermore, based on the studies in the narrative synthesis, body composition improvement was associated with steatosis resolution.

Conclusions

Based on the included studies, body composition improvement may be associated with a decrease in liver fat content in NAFLD.

Systematic review registration

Identifier: CRD42021278584.

The ancient CgPEPCK-1, not CgPECK-2, evolved into a multifunctional molecule as an intracellular enzyme and extracellular PRR

Phosphoenolpyruvate carboxykinase (PEPCK) is a well-known lyase involved in gluconeogenesis, while their evolution and function differentiation have not been fully understood. In this study, by constructing a phylogenetic tree to examine PEPCKs throughout the evolution from poriferans to vertebrates, Mollusk was highlighted as the only phylum to exhibit two distinct lineages, Mollusca_PEPCK-1 and Mollusca_PEPCK-2. Further study of two representative members from Crassostrea gigas (CgPEPCK-1 and CgPEPCK-2) showed that they both shared conserved sequences and structural characteristics of the catalytic enzyme, while CgPEPCK-2 displayed a higher expression level than CgPEPCK-1 in all tested tissues, and CgPEPCK-1 was specifically implicated in the immune defense against LPS stimulation and Vibrio splendidus infection. Functional analysis revealed that CgPEPCK-2 had stronger enzymatic activity than CgPEPCK-1, while CgPEPCK-1 exhibited stronger binding activity with various PAMPs, and only the protein of CgPEPCK-1 increased significantly in hemolymph during immune stimulation. All results supported that distinct sequence and function differentiations of the PEPCK gene family should have occurred since Mollusk. The more advanced evolutionary branch Mollusca_PEPCK-2 should preserve its essential function as a catalytic enzyme to be more specialized and efficient, while the ancient branch Mollusca_PEPCK-1 probably contained some members, such as CgPEPCK-1, that should be integrated into the immune system as an extracellular immune recognition receptor.

Mesenteric fat cryolipolysis attenuates insulin resistance in the Ossabaw swine model of the metabolic syndrome

BACKGROUND

The rising prevalence of insulin resistance (IR), metabolic syndrome, and type 2 diabetes are associated with increases in abdominal mesenteric fat. Adipocytes are sensitive to low temperatures, making cryolipolysis of mesenteric fat an attractive treatment modality to potentially reduce IR.

OBJECTIVES

We aimed to determine whether (1) cryolipolysis is safe in reducing the volume of the mesenteric fat and (2) reduction in mesenteric fat volume reduces indices of IR and glycemic dysfunction.

SETTING

Indiana University School of Medicine.

METHODS

A novel cooling device and method delivered cryolipolysis in a controlled manner to avoid tissue ablative temperatures. Ossabaw pigs (n = 8) were fed a high-fat diet for 9 months to develop visceral obesity, IR, and metabolic syndrome. Following laparotomy, mesenteric fat cryolipolysis (MFC) was performed in 5 pigs, while 3 served as sham surgery controls. The volume of the mesenteric fat was measured by computed tomography and compared with indices of glucose intolerance before and at 3 and 6 months postprocedure.

RESULTS

MFC safely reduced mesenteric fat volume by ∼30% at 3 months, which was maintained at 6 months. Body weight did not change in either the MFC or sham surgery control groups. Measure of glycemic control, insulin sensitivity, and blood pressure significantly improved after MFC compared with sham controls.

CONCLUSION

MFC reduces the volume of mesenteric fat and improves glycemic control in obese, IR Ossabaw pigs, without adverse effects.

Insulin Clearance in Health and Disease

Insulin action is impaired in type 2 diabetes. The functions of the hormone are an integrated product of insulin secretion from pancreatic β-cells and insulin clearance by receptor-mediated endocytosis and degradation, mostly in liver (hepatocytes) and, to a lower extent, in extrahepatic peripheral tissues. Substantial evidence indicates that genetic or acquired abnormalities of insulin secretion or action predispose to type 2 diabetes. In recent years, along with the discovery of the molecular foundation of receptor-mediated insulin clearance, such as through the membrane glycoprotein CEACAM1, a consensus has begun to emerge that reduction of insulin clearance contributes to the disease process. In this review, we consider the evidence suggesting a pathogenic role for reduced insulin clearance in insulin resistance, obesity, hepatic steatosis, and type 2 diabetes.

Genome-wide association study of abdominal MRI-measured visceral fat: The multiethnic cohort adiposity phenotype study

Few studies have explored the genetic underpinnings of intra-abdominal visceral fat deposition, which varies substantially by sex and race/ethnicity. Among 1,787 participants in the Multiethnic Cohort (MEC)-Adiposity Phenotype Study (MEC-APS), we conducted a genome-wide association study (GWAS) of the percent visceral adiposity tissue (VAT) area out of the overall abdominal area, averaged across L1-L5 (%VAT), measured by abdominal magnetic resonance imaging (MRI). A genome-wide significant signal was found on chromosome 2q14.3 in the sex-combined GWAS (lead variant rs79837492: Beta per effect allele = -4.76; P = 2.62 × 10-8) and in the male-only GWAS (lead variant rs2968545: (Beta = -6.50; P = 1.09 × 10-9), and one suggestive variant was found at 13q12.11 in the female-only GWAS (rs79926925: Beta = 6.95; P = 8.15 × 10-8). The negatively associated variants were most common in European Americans (T allele of rs79837492; 5%) and African Americans (C allele of rs2968545; 5%) and not observed in Japanese Americans, whereas the positively associated variant was most common in Japanese Americans (C allele of rs79926925, 5%), which was all consistent with the racial/ethnic %VAT differences. In a validation step among UK Biobank participants (N = 23,699 of mainly British and Irish ancestry) with MRI-based VAT volume, both rs79837492 (Beta = -0.026, P = 0.019) and rs2968545 (Beta = -0.028, P = 0.010) were significantly associated in men only (n = 11,524). In the MEC-APS, the association between rs79926925 and plasma sex hormone binding globulin levels reached statistical significance in females, but not in males, with adjustment for total adiposity (Beta = -0.24; P = 0.028), on the log scale. Rs79837492 and rs2968545 are located in intron 5 of CNTNAP5, and rs79926925, in an intergenic region between GJB6 and CRYL1. These novel findings differing by sex and racial/ethnic group warrant replication in additional diverse studies with direct visceral fat measurements.

Fatness, fitness and the aging brain: A cross sectional study of the associations between a physiological estimate of brain age and physical fitness, activity, sleep, and body composition

Introduction

Changes in brain structure and function occur with aging. However, there is substantial heterogeneity both in terms of when these changes begin, and the rate at which they progress. Understanding the mechanisms and/or behaviors underlying this heterogeneity may allow us to act to target and slow negative changes associated with aging.

Methods

Using T1 weighted MRI images, we applied a novel algorithm to determine the physiological age of the brain (brain-predicted age) and the predicted age difference between this physiologically based estimate and chronological age (BrainPAD) to 551 sedentary adults aged 65 to 84 with self-reported cognitive complaint measured at baseline as part of a larger study. We also assessed maximal aerobic capacity with a graded exercise test, physical activity and sleep with accelerometers, and body composition with dual energy x-ray absorptiometry. Associations were explored both linearly and logistically using categorical groupings.

Results

Visceral Adipose Tissue (VAT), Total Sleep Time (TST) and maximal aerobic capacity all showed significant associations with BrainPAD. Greater VAT was associated with higher (i.e,. older than chronological) BrainPAD (r = 0.149 p = 0.001)Greater TST was associated with higher BrainPAD (r = 0.087 p = 0.042) and greater aerobic capacity was associated with lower BrainPAD (r = - 0.088 p = 0.040). With linear regression, both VAT and TST remained significant (p = 0.036 and 0.008 respectively). Each kg of VAT predicted a 0.741 year increase in BrainPAD, and each hour of increased TST predicted a 0.735 year increase in BrainPAD. Maximal aerobic capacity did not retain statistical significance in fully adjusted linear models.

Discussion

Accumulation of visceral adipose tissue and greater total sleep time, but not aerobic capacity, total daily physical activity, or sleep quantity and/or quality are associated with brains that are physiologically older than would be expected based upon chronological age alone (BrainPAD).

Regulation of Insulin Clearance by Non-Esterified Fatty Acids

Insulin stores lipid in adipocytes and prevents lipolysis and the release of non-esterified fatty acids (NEFA). Excessive release of NEFA during sustained energy supply and increase in abdominal adiposity trigger systemic insulin resistance, including in the liver, a major site of insulin clearance. This causes a reduction in insulin clearance as a compensatory mechanism to insulin resistance in obesity. On the other hand, reduced insulin clearance in the liver can cause chronic hyperinsulinemia, followed by downregulation of insulin receptor and insulin resistance. Delineating the cause–effect relationship between reduced insulin clearance and insulin resistance has been complicated by the fact that insulin action and clearance are mechanistically linked to insulin binding to its receptors. This review discusses how NEFA mobilization contributes to the reciprocal relationship between insulin resistance and reduced hepatic insulin clearance, and how this may be implicated in the pathogenesis of non-alcoholic fatty liver disease.

Fetal programming in sheep: Effects on pre- and postnatal organs and glands development in lambs

The present systematic review and meta-analysis aim to summarize the effects of maternal undernutrition or overnutrition during pregnancy on the absolute weight and relative weight of the organs (liver, kidneys, heart, spleen, and lung) and glands (adrenal, pancreas, and thyroid) measured during gestation, birth and the postnatal period in lambs. After completing the search, selection, and data extraction steps, the measure of effect was generated by the individual comparison of each variable response compared with the average of the control and treated group (undernutrition or overnutrition) using the DerSimonian and Laird method for random effects. The liver was the organ most affected by maternal undernutrition, as the absolute weight of the liver was reduced during pregnancy, birth, and the postnatal period. The extent of this effect is related to the duration of the intervention. Reductions in the absolute fetal weight of the lungs and spleen have also been observed. No change in organs weight were observed when the results were expressed as relative weight. For overnutrition, the fetal weight of the liver was reduced to both absolute and relative values. In contrast, the relative weight of the kidneys has been increased. For the glands analyzed, no changes in weight were observed in either scenario (absolute or relative weight). Thus, the organs are more likely to suffer weight changes, especially during pregnancy, as a result of maternal nutrition. However, this change in organ weight seems to be closely related to the reduction in body weight of the progeny as a whole.

Non-linear Associations Between Visceral Adiposity Index and Cardiovascular and Cerebrovascular Diseases: Results From the NHANES (1999–2018)

Objective

To investigate associations between visceral adiposity index (VAI) and cardiovascular and cerebrovascular diseases (CCDs) in the American population from 1999 to 2018.

Methods

Data from the National Health and Nutrition Examination Survey (1998–2018) were analyzed in this study. Specifically, VAI scores were calculated using sex-specific equations that incorporate body mass index, waist circumference (WC), high-density lipoprotein (HDL), triglycerides (TG), and cholesterol. Weighted logistic regression analysis was conducted to assess the relationship between VAI tertile and increased risk of CCDs. Restricted cubic splines were used to evaluate the non-linear relationship between VAI and CCDs, such as heart failure, angina, heart attack, stroke, hypertension, and coronary heart disease. Sensitivity analysis was conducted, using VAI quartiles as independent variables.

Results

A total of 22,622 subjects aged over 20 years were included. In the fully adjusted model after controlling for covariates, the third VAI tertile was more strongly associated with CCDs than the first VAI tertile, with odds ratio (OR) and 95% confidence interval (95% CI) values for angina of 2.86, 1.68–4.85; heart attack, 1.75, 1.14–2.69; stroke, 2.01, 1.23–3.26; hypertension, 2.28, 1.86–2.78; and coronary heart disease, 1.78, 1.32–2.41; but there was no significant association with heart failure (p > 0.05). Restricted cubic splines revealed parabolic relationships between VAI score and angina (p for non-linear = 0.03), coronary heart disease (p for non-linear = 0.01), and hypertension (p for non-linear < 0.001). Sensitivity analysis indicated that the fourth VAI quartile was more strongly associated with an increased risk of angina (OR = 2.92, 95% CI, 1.49–5.69), hypertension (OR = 2.37, 95% CI, 1.90–2.97), heart attack (OR = 1.77, 95% CI, 1.09–2.88), and coronary heart disease (OR = 1.89, 95% CI, 1.24–2.86) than the first VAI quartile. VAI had superior predictive power for prevalent CCDs than other independent indicators (p < 0.05).

Conclusion

Visceral adiposity index score is positively correlated with angina, heart attack, stroke, hypertension, and coronary heart disease, but not heart failure, and the relationships between VAI score and angina, hypertension, and coronary heart disease are non-linear.

Anti-Obesity Effect of Dyglomera® Is Associated with Activation of the AMPK Signaling Pathway in 3T3-L1 Adipocytes and Mice with High-Fat Diet-Induced Obesity

Dyglomera^® is an aqueous ethanol extract of the fruit pods of Dichrostachys glomerata, a Cameroonian spice. Several studies have shown its anti-diabetic and anti-obesity effects. However, the underlying mechanisms for such effects remain unclear. Thus, the objective of this study was to investigate the anti-obesity effect of Dyglomera^® and its underlying mechanisms in mice with high-fat diet-induced obesity and 3T3-L1 adipocytes. Our results revealed that Dyglomera^® inhibited adipogenesis and lipogenesis by regulating AMPK phosphorylation in white adipose tissues (WATs) and 3T3-L1 adipocytes and promoted lipolysis by increasing the expression of lipolysis-related proteins. These results suggest that Dyglomera^® can be used as an effective dietary supplement for treating obesity due to its modulating effect on adipogenesis/lipogenesis and lipolysis.

Non-alcoholic fatty liver disease: a multi-system disease influenced by ageing and sex, and affected by adipose tissue and intestinal function

In recent years, a wealth of factors are associated with increased risk of developing non-alcoholic fatty liver disease (NAFLD) and NAFLD is now thought to increase the risk of multiple extra-hepatic diseases. The aim of this review is first to focus on the role of ageing and sex as key, poorly understood risk factors in the development and progression of NAFLD. Secondly, we aim to discuss the roles of white adipose tissue (WAT) and intestinal dysfunction, as producers of extra-hepatic factors known to further contribute to the pathogenesis of NAFLD. Finally, we aim to summarise the role of NAFLD as a multi-system disease affecting other organ systems beyond the liver. Both increased age and male sex increase the risk of NAFLD and this may be partly driven by alterations in the distribution and function of WAT. Similarly, changes in gut microbiota composition and intestinal function with ageing and chronic overnutrition are likely to contribute to the development of NAFLD both directly (i.e. by affecting hepatic function) and indirectly via exacerbating WAT dysfunction. Consequently, the presence of NAFLD significantly increases the risk of various extra-hepatic diseases including CVD, type 2 diabetes mellitus, chronic kidney disease and certain extra-hepatic cancers. Thus changes in WAT and intestinal function with ageing and chronic overnutrition contribute to the development of NAFLD – a multi-system disease that subsequently contributes to the development of other chronic cardiometabolic diseases.

Canine Geriatric Syndrome: A Framework for Advancing Research in Veterinary Geroscience

Biological aging is the single most important risk factor for disease, disability, and ultimately death in geriatric dogs. The effects of aging in companion dogs also impose significant financial and psychological burdens on their human caregivers. The underlying physiologic processes of canine aging may be occult, or early signs of aging may be ignored because of the misconception that biological aging is natural and therefore inevitable. The ability to detect, quantify, and mitigate the deleterious processes of canine aging would greatly enhance veterinary preventative medicine and animal welfare. In this paper we propose a new conceptual framework for aging in dogs, the Canine Geriatric Syndrome (CGS). CGS consists of the multiple, interrelated physical, functional, behavioral, and metabolic changes that characterize canine aging as well as the resulting clinical manifestations, including frailty, diminished quality of life, and age-associated disease. We also identify potential key components of a CGS assessment tool, a clinical instrument that would enable veterinarians to diagnose CGS and would facilitate the development and testing of interventions to prolong healthspan and lifespan in dogs by directly targeting the biological mechanisms of aging. There are many gaps in our knowledge of the mechanisms and phenotype of aging in dogs that must be bridged before a CGS assessment tool can be deployed. The conceptual framework of CGS should facilitate identifying these gaps and should stimulate research to better characterize the processes and effects of aging in dogs and to identify the most promising preventative strategies to target these.

Obesity I: Overview and molecular and biochemical mechanisms

Obesity is a chronic, relapsing condition characterized by excess body fat. Its prevalence has increased globally since the 1970s, and the number of obese and overweight people is now greater than those underweight. Obesity is a multifactorial condition, and as such, many components contribute to its development and pathogenesis. This is the first of three companion reviews that consider obesity. This review focuses on the genetics, viruses, insulin resistance, inflammation, gut microbiome, and circadian rhythms that promote obesity, along with hormones, growth factors, and organs and tissues that control its development. It shows that the regulation of energy balance (intake vs. expenditure) relies on the interplay of a variety of hormones from adipose tissue, gastrointestinal tract, pancreas, liver, and brain. It details how integrating central neurotransmitters and peripheral metabolic signals (e.g., leptin, insulin, ghrelin, peptide YY_3-36) is essential for controlling energy homeostasis and feeding behavior. It describes the distinct types of adipocytes and how fat cell development is controlled by hormones and growth factors acting via a variety of receptors, including peroxisome proliferator-activated receptor-gamma, retinoid X, insulin, estrogen, androgen, glucocorticoid, thyroid hormone, liver X, constitutive androstane, pregnane X, farnesoid, and aryl hydrocarbon receptors. Finally, it demonstrates that obesity likely has origins in utero. Understanding these biochemical drivers of adiposity and metabolic dysfunction throughout the life cycle lends plausibility and credence to the "obesogen hypothesis" (i.e., the importance of environmental chemicals that disrupt these receptors to promote adiposity or alter metabolism), elucidated more fully in the two companion reviews.

Slc7a8 Deletion Is Protective against Diet-Induced Obesity and Attenuates Lipid Accumulation in Multiple Organs

Simple Summary

The development of obesity can be attributed to adipocyte hypertrophy or hyperplasia which lead to increased adiposity. The C57BL/6 mouse is an excellent model to study metabolic syndromes often associated with obesity development. Mice fed on a high-fat diet are susceptible to weight gain, leading to the development of obesity and its associated metabolic syndrome. Here, we report findings from targeting a novel potential human adipogenic gene (SLC7A8) under conditions of obesity development using a mouse model of diet-induced obesity (DIO). The results indicate that deleting slc7a8 in mice significantly protects against DIO and improves glucose metabolism. Deficiency in slc7a8 was observed to significantly attenuate adipocyte hypertrophy in white and brown adipose tissue and to reduce lipid accumulation in many organs. Furthermore, inflammation was significantly reduced in the adipose tissue and liver of slc7a8-deficient mice with DIO. Overall, the results from this study show that slc7a8 is an important molecular regulator of obesity development and mediates its function by reducing lipid accumulation in multiple organs. Hence, SLC7A8 could serve as a potential therapeutic target to combat the development of obesity and other pathophysiological conditions associated with excess lipid accumulation.

Abstract

Adipogenesis, through adipocyte hyperplasia and/or hypertrophy, leads to increased adiposity, giving rise to obesity. A genome-wide transcriptome analysis of in vitro adipogenesis in human adipose-derived stromal/stem cells identified SLC7A8 (Solute Carrier Family 7 Member 8) as a potential novel mediator. The current study has investigated the role of SLC7A8 in adipose tissue biology using a mouse model of diet-induced obesity. slc7a8 knockout (KO) and wildtype (WT) C57BL/6J mice were fed either a control diet (CD) or a high-fat diet (HFD) for 14 weeks. On the HFD, both WT and KO mice (WTHFD and KOHFD) gained significantly more weight than their CD counterparts. However, KOHFD gained significantly less weight than WTHFD. KOHFD had significantly reduced levels of glucose intolerance compared with those observed in WTHFD. KOHFD also had significantly reduced adipocyte mass and hypertrophy in inguinal, mesenteric, perigonadal, and brown adipose depots, with a corresponding decrease in macrophage infiltration. Additionally, KOHFD had decreased lipid accumulation in the liver, heart, gastrocnemius muscle, lung, and kidney. This study demonstrates that targeting slc7a8 protects against diet-induced obesity by reducing lipid accumulation in multiple organs and suggests that if targeted, has the potential to mitigate the development of obesity-associated comorbidities.

The effect of adenosine monophosphate-activated protein kinase on lipolysis in adipose tissue: an historical and comprehensive review

CONTEXT

Lipolysis is one of the most important pathways for energy management, its control in the adipose tissue (AT) is a potential therapeutic target for metabolic diseases. Adenosine Mono Phosphate-activated Protein Kinase (AMPK) is a key regulatory enzyme in lipids metabolism and a potential target for diabetes and obesity treatment.

OBJECTIVE

The aim of this work is to analyse the existing information on the relationship of AMPK and lipolysis in the AT.

METHODS

A thorough search of bibliography was performed in the databases Scopus and Web of Knowledge using the terms lipolysis, adipose tissue, and AMPK, the unrelated publications were excluded, and the documents were analysed.

RESULTS

Sixty-three works were found and classified in 3 categories: inhibitory effects, stimulatory effect, and diverse relationships; remarkably, the newest researches support an upregulating relationship of AMPK over lipolysis.

CONCLUSION

The most probable reality is that the relationship AMPK-lipolysis depends on the experimental conditions.

Abdominal Visceral Adipose Tissue and All-Cause Mortality: A Systematic Review

INTRODUCTION

Increased abdominal visceral adipose tissue (VAT) implies an adverse cardio-metabolic profile. We examined the association of abdominal VAT parameters and all-cause mortality risk.

METHODS

We systematically searched four databases. We performed citations/articles screening, data abstraction, and quality assessment in duplicate and independently (CRD42020205021).

RESULTS

We included 12 cohorts, the majority used computed tomography to assess abdominal VAT area. Six cohorts with a mean age ≤ 65 years, examining all-cause mortality risk per increment in VAT area (cm²) or volume (cm³), showed a 11-98% relative risk increase with higher VAT parameters. However, the association lost significance after adjusting for glycemic indices, body mass index, or other fat parameters. In 4 cohorts with a mean age >65 years, the findings on mortality were inconsistent. Conversely, in two cohorts (mean age 73-77 years), a higher VAT density, was inversely proportional to VAT area, and implied a higher mortality risk.

CONCLUSION

A high abdominal VAT area seems to be associated with increased all-cause mortality in individuals ≤ 65 years, possibly mediated by metabolic complications, and not through an independent effect. This relationship is weaker and may reverse in older individuals, most likely secondary to confounding bias and reverse causality. An individual participant data meta-analysis is needed to confirm our findings, and to define an abdominal VAT area cutoff implying increased mortality risk.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=205021, identifier CRD42020205021.

How much abdominal fat do obese patients lose short term after laparoscopic sleeve gastrectomy? A quantitative study evaluated with MRI

Background

This study aimed to elucidate the changes in the amount of abdominal adipose tissue after laparoscopic sleeve gastrectomy in obese Chinese patients over a relatively short follow-up period and to analyze the differences in the effects of surgery between genders.

Methods

Ninety-one patients were enrolled in the study, including 18 males and 73 females. These patients underwent laparoscopic sleeve gastrectomy between November 2017 and November 2019. Before and short term after surgery, the areas of subcutaneous/visceral adipose tissue and the liver proton density fat fraction were calculated with upper abdominal magnetic resonance (MR) examinations.

Results

Approximately 100 days after surgery, the median values of weight loss and body mass index reduction were 23.1 kg and 8.1 kg/m², respectively. The patients achieved a greater absolute loss of subcutaneous adipose tissue index than of visceral adipose tissue index (3.2×10^-3 vs. 1.6×10^-3, P<0.001). The amount of weight loss, body mass index loss and absolute/relative reduction in visceral adipose tissue index were much greater in males than in females (31.7 vs. 21.7 kg, P<0.001; 9.8 vs. 7.9 kg/m², P=0.016; 2.5×10^-3 vs. 1.3×10^-3, P=0.007; 28.2% vs. 20.9%, P=0.029). There was a correlation between decreased amounts in subcutaneous and visceral adipose tissue in sum and weight loss (r=0.282, P=0.032). The absolute/relative reduction in visceral adipose tissue index was also correlated with absolute/relative reduction in liver proton density fat fraction (r=0.283, P=0.013; r=0.372, P=0.001).

Conclusions

The reductions in body weight and visceral fat were more significant in male patients. The sum of absolute reduction in subcutaneous and visceral fat deposits was correlated with weight loss, in all patients enrolled. For severely obese patients, an upper abdominal MR examination could assess the body tissue composition and how it changes after bariatric surgery.

Visceral adiposity index is associated with arterial stiffness in hypertensive adults with normal-weight: the china H-type hypertension registry study

Background

Limited information is available on arterial stiffness risk among hypertensive patients with metabolically abnormal but normal weight. Visceral adiposity index (VAI) is a novel indicator for visceral fat mass and metabolism, however, whether can be used to assessed arterial stiffness in a normal-weight population remains unclear. The goal of this study was to examine the independent association of VAI with arterial stiffness in normal-weight hypertensive patients.

Methods

3258 participants recruited from the China H-type Hypertension Registry Study. VAI value was calculated using sex-specific equations. High arterial stiffness was defined as baPWV ≥ 18 m/s. Multivariable regression analysis was used to identify the association of VAI with baPWV and high arterial stiffness.

Results

Of participants, 50.5% (1644) were males, the mean age was 65.5 (SD, 9.1) years. Mean VAI and baPWV were 2.0 (SD, 2.3) and 18.2 (SD, 3.9) m/s, respectively. For each unit increase of lg VAI in multivariable regression analysis, there was a 1.05 m/s increase in baPWV (95% CI 0.67, 1.43) and a 2.13-fold increase in the risk of high arterial stiffness (95% CI 1.59, 2.86). In all models, the VAI was consistently and significantly associated with baPWV after adjustment for different confounders. High VAI levels were stably associated with baPWV in all subgroups.

Conclusions

We found positive association of VAI with baPWV and high arterial stiffness in normal-weight adults with hypertension. The establishment of this association could help the arterial stiffness risk stratification in normal-weight hypertensive populations, who are frequently overlooked in preventing cardiovascular disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-021-00617-5.

Dipeptidyl peptidase-4 inhibitor, anagliptin, alters hepatic insulin clearance in relation to the glycemic status in Japanese individuals with type 2 diabetes

AIMS/INTRODUCTION

This study investigated the impact of the dipeptidyl peptidase-4 inhibitor, anagliptin, on hepatic insulin clearance (HIC) in Japanese type 2 diabetes patients and explored its relationship to glycemic status.

MATERIALS AND METHODS

Data on 765 participants in anagliptin phase 2 and 3 studies were analyzed. Adjusted changes in variables during 12 weeks of anagliptin therapy were compared with a placebo. HIC was calculated as the ratio, C-peptide area under the curve 0-120 min to insulin area under the curve 0-120 min, after a meal tolerance test. To explore the effects of baseline HIC levels on variables, participants receiving anagliptin were divided according to quartiles of baseline HIC. Furthermore, multivariate analysis investigated the association between baseline HIC levels and glycemic status.

RESULTS

Anagliptin significantly reduced glycosylated hemoglobin levels (P < 0.001 vs placebo) and HIC levels (P < 0.01). Longer duration of diabetes, lower body mass index, higher glycosylated hemoglobin and lower insulin secretion capacity were observed with increases in baseline HIC levels. Improvements in glycosylated hemoglobin, glycoalbumin and 1,5-anhydroglucitol levels were greater in the relatively higher HIC group (baseline HIC levels ≥median) than in the lower HIC group (

CONCLUSIONS

Anagliptin affected HIC levels according to HIC baseline levels. Higher baseline HIC values might result in improved hyperglycemia through reduced HIC.

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Key Words

• Dipeptidyl peptidase-4 inhibitor
• Hepatic insulin clearance
• Meal tolerance test

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MESH Headings

• Aged
• Asian People
• Diabetes Mellitus, Type 2/drug therapy
• Diabetes Mellitus, Type 2/metabolism
• Dipeptidyl-Peptidase IV Inhibitors/pharmacology
• Dipeptidyl-Peptidase IV Inhibitors/therapeutic use
• Double-Blind Method
• Female
• Humans
• Insulin/metabolism
• Liver/metabolism
• Male
• Middle Aged
• Pyrimidines/pharmacology
• Pyrimidines/therapeutic use

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Grants

• Sanwa Kagaku Kenkyusho Co., Ltd.
• Kowa Co., Ltd

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Affiliation(s)

Takahiro Abe Department of Hematology, Endocrinology and MetabolismNiigata University Faculty of MedicineNiigataJapan
Yasuhiro Matsubayashi Department of Hematology, Endocrinology and MetabolismNiigata University Faculty of MedicineNiigataJapan
Sayaka Muragishi Kowa Co., Ltd.TokyoJapan
Akihiro Yoshida Department of Hematology, Endocrinology and MetabolismNiigata University Faculty of MedicineNiigataJapan Kowa Co., Ltd.TokyoJapan
Hideki Suganami Kowa Co., Ltd.TokyoJapan
Kenichi Furusawa Sanwa Kagaku Kenkyusho Co., Ltd.NagoyaJapan
Kazuya Fujihara Department of Hematology, Endocrinology and MetabolismNiigata University Faculty of MedicineNiigataJapan
Shiro Tanaka Department of Clinical BiostatisticsGraduate School of Medicine Kyoto UniversityKyotoJapan
Kohei Kaku Kawasaki Medical SchoolOkayamaJapan
Hirohito Sone Department of Hematology, Endocrinology and MetabolismNiigata University Faculty of MedicineNiigataJapan

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Clinical evaluation of urinary liver-type fatty acid-binding protein for the diagnosis of renal diseases in dogs

Liver-type fatty acid-binding protein (L-FABP) is a biomarker for the early detection of renal diseases in humans. L-FABP is a cytotoxic oxidation product secreted from the proximal tubules under ischemic and oxidative stress conditions. First, L-FABP gene expression in the kidney and liver was evaluated. Next, the urinary L-FABP concentrations in dogs with or without renal diseases were measured using a novel enzyme-linked immunosorbent assay kit. Urinary L-FABP was normalized relative to urinary creatinine (uCre) concentrations (µg/g uCre). Finally, the relationships between urinary L-FABP and renal biomarkers used in canine medicine or serum alanine transaminase (ALT) as an indicator of liver damage were examined. Serum and urine samples from 94 client-owned dogs including 23 dogs with renal diseases and 71 dogs without renal diseases were used for analysis. Relative L-FABP gene expression was confirmed both in the liver and kidney. Dogs with renal diseases had a significantly higher urinary L-FABP than those without, and its predictive cutoff value was 26 µg/g uCre. Urinary L-FABP was significantly correlated with serum creatinine (r=0.4674, P<0.01), urea nitrogen (r=0.4907, P<0.01), urine specific gravity (r=−0.5100, P<0.01), and urine protein/creatinine ratio (r=0.7216, P<0.01), but not with serum ALT. Hence, dogs with a high urinary L-FABP value were more likely to have renal diseases.

Anti-Obesity and Lipid Metabolism Effects of Ulmus davidiana var. japonica in Mice Fed a High-Fat Diet

The root bark of Ulmus davidiana var. japonica (Japanese elm) is used in Korea and other East Asian countries as a traditional herbal remedy to treat a variety of inflammatory diseases and ailments such as edema, gastric cancer and mastitis. For this study, we investigated the lipid metabolism and anti-obesity efficacy of ethyl alcohol extract of Ulmus davidiana var. japonica root bark (UDE). First, HPLC was performed to quantify the level of (+)-catechin, the active ingredient of UDE. In the following experiments, cultured 3T3-L1 pre-adipocytes and high-fat diet (HFD)-fed murine model were studied for anti-obesity efficacy by testing the lipid metabolism effects of UDE and (+)-catechin. In the test using 3T3-L1 pre-adipocytes, treatment with UDE inhibited adipocyte differentiation and significantly reduced the production of adipogenic genes and transcription factors PPARγ, C/EBPα and SREBP-1c. HFD-fed, obese mice were administered with UDE (200 mg/kg per day) and (+)-catechin (30 mg/kg per day) by oral gavage for 4 weeks. Weight gain, epididymal and abdominal adipose tissue mass were significantly reduced, and a change in adipocyte size was observed in the UDE and (+)-catechin treatment groups compared to the untreated control group (***p < 0.001). Significantly lower total cholesterol and triglyceride levels were detected in UDE-treated HFD mice compared to the control, revealing the efficacy of UDE. In addition, it was found that lipid accumulation in hepatocytes was also significantly reduced after administration of UDE. These results suggest that UDE has significant anti-obesity and lipid metabolism effects through inhibition of adipocyte differentiation and adipogenesis.

Lower insulin clearance is associated with increased risk of type 2 diabetes in Native Americans

AIMS/HYPOTHESIS

Impaired insulin clearance is implicated in the pathogenesis of type 2 diabetes, but prospective evidence remains limited. Therefore, we sought to identify factors associated with the metabolic clearance rate of insulin (MCRI) and to investigate whether lower MCRI is associated with increased risk of incident type 2 diabetes.

METHODS

From a longitudinal cohort, 570 adult Native Americans without diabetes living in the Southwestern United States were characterised at baseline and 448 participants were monitored over a median follow-up period of 7.9 years with 146 (32%) incident cases of diabetes identified (fasting plasma glucose ≥7.0 mmol/l, 2 h plasma glucose [2-h PG] ≥11.1 mmol/l, or clinical diagnosis). At baseline, participants underwent dual-energy x-ray absorptiometry or hydrodensitometry to assess body composition, a 75 g OGTT, an IVGTT to assess acute insulin response (AIR), and a hyperinsulinaemic-euglycaemic clamp to assess MCRI and insulin action (M).

RESULTS

In adjusted linear models, MCRI was inversely associated with body fat percentage (r = -0.35), fasting plasma insulin (r = -0.55) and AIR (r = -0.22), and positively associated with M (r = 0.17; all p < 0.0001). In multivariable Cox proportional hazard models, lower MCRI was associated with an increased risk of diabetes after adjustment for age, sex, heritage, body fat percentage, AIR, M, fasting plasma glucose, 2-h PG, and fasting plasma insulin (HR per one-SD difference in MCRI: 0.77; 95% CI 0.61, 0.98; p = 0.03).

CONCLUSIONS/INTERPRETATION

Lower MCRI is associated with an unfavourable metabolic phenotype and is associated with incident type 2 diabetes independent of established risk factors.

CLINICAL TRIAL REGISTRATION NUMBERS

ClinicalTrials.gov NCT00339482; NCT00340132.

100th anniversary of the discovery of insulin perspective: insulin and adipose tissue fatty acid metabolism

Insulin inhibits systemic nonesterified fatty acid (NEFA) flux to a greater degree than glucose or any other metabolite. This remarkable effect is mainly due to insulin-mediated inhibition of intracellular triglyceride (TG) lipolysis in adipose tissues and is essential to prevent diabetic ketoacidosis, but also to limit the potential lipotoxic effects of NEFA in lean tissues that contribute to the development of diabetes complications. Insulin also regulates adipose tissue fatty acid esterification, glycerol and TG synthesis, lipogenesis, and possibly oxidation, contributing to the trapping of dietary fatty acids in the postprandial state. Excess NEFA flux at a given insulin level has been used to define in vivo adipose tissue insulin resistance. Adipose tissue insulin resistance defined in this fashion has been associated with several dysmetabolic features and complications of diabetes, but the mechanistic significance of this concept is not fully understood. This review focusses on the in vivo regulation of adipose tissue fatty acid metabolism by insulin and the mechanistic significance of the current definition of adipose tissue insulin resistance. One hundred years after the discovery of insulin and despite decades of investigations, much is still to be understood about the multifaceted in vivo actions of this hormone on adipose tissue fatty acid metabolism.

Body composition and breast cancer risk and treatment: mechanisms and impact

PURPOSE

The purpose of this review is to clarify the association of body composition with breast cancer risk and treatment, including physiological mechanisms, and to elucidate strategies for overcoming unfavorable body composition changes that relate to breast cancer progression.

METHODS

We have summarized updated knowledge regarding the mechanism of the negative association of altered body composition with breast cancer risk and treatment. We also review strategies for reversing unfavorable body composition based on the latest clinical trial results.

RESULTS

Body composition changes in patients with breast cancer typically occur during menopause or as a result of chemotherapy or endocrine therapy. Dysfunction of visceral adipose tissue (VAT) in the setting of obesity underlies insulin resistance and chronic inflammation, which can lead to breast cancer development and progression. Insulin resistance and chronic inflammation are also observed in patients with breast cancer who have sarcopenia or sarcopenic obesity. Nutritional support and a personalized exercise program are the fundamental interventions for reversing unfavorable body composition. Other interventions that have been explored in specific situations include metformin, testosterone, emerging agents that directly target the adipocyte microenvironment, and bariatric surgery.

CONCLUSIONS

A better understanding of the biology of body composition phenotypes is key to determining the best intervention program for patients with breast cancer.

PAPPA-mediated adipose tissue remodeling mitigates insulin resistance and protects against gestational diabetes in mice and humans

Pregnancy is a physiological state of continuous adaptation to changing maternal and fetal nutritional needs, including a reduction of maternal insulin sensitivity allowing for appropriately enhanced glucose availability to the fetus. However, excessive insulin resistance in conjunction with insufficient insulin secretion results in gestational diabetes mellitus (GDM), greatly increasing the risk for pregnancy complications and predisposing both mothers and offspring to future metabolic disease. Here, we report a signaling pathway connecting pregnancy-associated plasma protein A (PAPPA) with adipose tissue expansion in pregnancy. Adipose tissue plays a central role in the regulation of insulin sensitivity, and we show that, in both mice and humans, pregnancy caused remodeling of adipose tissue evidenced by altered adipocyte size, vascularization, and in vitro expansion capacity. PAPPA is known to be a metalloprotease secreted by human placenta that modulates insulin-like growth factor (IGF) bioavailability through prolteolysis of IGF binding proteins (IGFBPs) 2, 4, and 5. We demonstrate that recombinant PAPPA can stimulate ex vivo human adipose tissue expansion in an IGFBP-5- and IGF-1-dependent manner. Moreover, mice lacking PAPPA displayed impaired adipose tissue remodeling, pregnancy-induced insulin resistance, and hepatic steatosis, recapitulating multiple aspects of human GDM. In a cohort of 6361 pregnant women, concentrations of circulating PAPPA are inversely correlated with glycemia and odds of developing GDM. These data identify PAPPA and the IGF signaling pathway as necessary for the regulation of maternal adipose tissue physiology and systemic glucose homeostasis, with consequences for long-term metabolic risk and potential for therapeutic use.

Intraperitoneal, but not retroperitoneal, visceral adipose tissue is associated with diabetes mellitus: a cross-sectional, retrospective pilot analysis

AIM

Diabetes mellitus (DM) is associated with adverse outcomes, and visceral adipose tissue (VAT), classified into intraperitoneal VAT (IVAT) and retroperitoneal VAT (RVAT), is associated with insulin resistance. This study aimed to evaluate the association of IVAT and RVAT with the prevalence or incidence of DM.

METHODS

In this cross-sectional, retrospective, cohort study, the prevalence and incidence of DM was analyzed in 803 and 624 middle-aged Japanese participants, respectively. The cross-sectional area of the abdominal adipose tissue was evaluated from an unenhanced computed tomography scan at the third lumbar vertebrae, and the IVAT or RVAT was analyzed using specialized software. The areas were normalized for the square value of the participants' height in meters and described as the IVAT or RVAT area index.

RESULTS

The IVAT area index (adjusted odds ratio [OR], 1.04; 95% confidence intervals [CI], 1.02-1.07, per 1.0 cm²/m²) or IVAT/RVAT area ratio (1.89; 1.23-2.85, per 1.0) was independently associated with the prevalence of DM, whereas the RVAT area index was not. During a follow-up (mean) of 3.7 years, 30 participants were diagnosed with DM. The IVAT area index (adjusted hazards ratio [HR], 1.02; 95% CI 1.003-1.04, per 1.0 cm²/m²) or IVAT/RVAT area ratio (2.25; 1.40-3.43, per 1.0) was independently associated with the incidence of DM, whereas the RVAT area index was not.

CONCLUSIONS

IVAT, but not RVAT, is associated with the prevalence or incidence of DM.

Eriocitrin Improves Adiposity and Related Metabolic Disorders in High-Fat Diet-Induced Obese Mice

Eriocitrin (EC) is an abundant flavonoid in lemons, which is known as a strong antioxidant agent. This study investigated the biological and molecular mechanisms underlying the anti-obesity effect of EC in high-fat diet (HFD)-fed obese mice. C57BL/6N mice were fed an HFD (40 kcal% fat) with or without 0.005% (w/w) EC for 16 weeks. Dietary EC improved adiposity by increasing adipocyte fatty acid (FA) oxidation, energy expenditure, and mRNA expression of thermogenesis-related genes in brown adipose tissue (BAT) and skeletal muscle, whereas it also decreased lipogenesis-related gene expression in white adipose tissue. In addition to adiposity, EC prevented hepatic steatosis by diminishing lipogenesis while enhancing FA oxidation in the liver and fecal lipid excretion, which was linked to attenuation of hyperlipidemia. Moreover, EC improved insulin sensitivity by decreasing hepatic gluconeogenesis and proinflammatory responses. These findings indicate that EC may protect against diet-induced adiposity and related metabolic disorders by controlling thermogenesis of BAT and skeletal muscle, FA oxidation, lipogenesis, fecal lipid excretion, glucose utilization, and gluconeogenesis.

Moderate Aerobic Exercise Training Prevents the Augmented Hepatic Glucocorticoid Response Induced by High-Fat Diet in Mice

Glucocorticoids (GCs) are critical regulators of energy balance. Their deregulation is associated with the development of obesity and metabolic syndrome. However, it is not understood if obesity alters the tissue glucocorticoid receptor (GR) response, and moreover whether a moderate aerobic exercise prevents the alteration in GR response induced by obesity. Methods: To evaluate the GR response in obese mice, we fed C57BL6J mice with a high-fat diet (HFD) for 12 weeks. Before mice were sacrificed, we injected them with dexamethasone. To assess the exercise role in GR response, we fed mice an HFD and subjected them to moderate aerobic exercise three times a week. Results: We found that mice fed a high-fat diet for 12 weeks developed hepatic GC hypersensitivity without changes in the gastrocnemius or epididymal fat GR response. Therefore, moderate aerobic exercise improved glucose tolerance, increased the corticosterone plasma levels, and prevented hepatic GR hypersensitivity with an increase in epididymal fat GR response. Conclusion: Collectively, our results suggest that mice with HFD-induced obesity develop hepatic GR sensitivity, which could enhance the metabolic effects of HFD in the liver. Moreover, exercise was found to be a feasible non-pharmacological strategy to prevent the deregulation of GR response in obesity.

The relationship between pancreas steatosis and the risk of metabolic syndrome and insulin resistance in Chinese adolescents with concurrent obesity and non-alcoholic fatty liver disease

BACKGROUND

The incidence of childhood obesity and associated comorbidities are on an increasing trend worldwide. More than 340 million children and adolescents aged between 5 and 19 years old were overweight or had obesity in 2016, from which over 124 million children and adolescents (6% of girls and 8% of boys) had obesity.

OBJECTIVE

To describe the relationship between pancreas steatosis, body fat and the risk of metabolic syndrome, insulin resistance in Hong Kong Chinese adolescents with both obesity and non-alcoholic fatty liver disease (NAFLD).

METHODS

Fifty two adolescents with obesity and NAFLD were analysed (14-18 years), stratified into fatty and non-fatty pancreas groups using chemical shift encoded MRI-pancreas proton density fat fraction ≥5%. Pancreatic, abdominal subcutaneous adipose tissue (SAT)/visceral adipose tissue (VAT) volumes, biochemical and anthropometric parameters were measured. Mann-Whitney U test, multiple linear/binary logistic regression analyses and odds ratios were used.

RESULTS

Fifty percent had fatty pancreas, 38% had metabolic syndrome and 81% had insulin resistance. Liver proton density fat fraction (PDFF) and VAT were independent predictors of insulin resistance (P = .006, .016). Pancreas and liver PDFF were both independent predictors of beta cells dysfunction (P = .015, .050) and metabolic syndrome (P = .021, .041). Presence of fatty pancreas in obesity was associated with insulin resistance (OR = 1.58, 95% CI = 0.39-6.4) and metabolic syndrome (OR = 1.70, 95% CI = 0.53-5.5).

CONCLUSION

A significant causal relationship exists between fatty pancreas, fatty liver, body fat and the risk of developing metabolic syndrome and insulin resistance.

KEY POINTS

Fatty pancreas is a common finding in adolescents with obesity, with a prevalence rate of 50% in this study cohort. Liver PDFF and VAT are independent predictors of insulin resistance while pancreas PDFF and liver PDFF are independent predictors of both beta cells dysfunction and metabolic syndrome. Presence of fatty pancreas at imaging should not be considered as a benign finding but rather as an imaging biomarker of emerging pancreatic metabolic and endocrine dysfunction.

Imaging of body composition in children

Overweight and obesity in children and adolescents have become a worldwide public health concern with an ever-increasing prevalence. An excessive accumulation of intraabdominal fat tissue increases the risk of developing insulin resistance, diabetes, and cardiovascular diseases in adulthood. Body composition has a role in metabolism regulation in children and adolescents with differences between genders and age groups. Until recently, Air Displacement Plethysmography and Dual-energy X-ray Absorptiometry (DXA) have been the most common techniques used to assess body composition in children. Ultrasound (US) is an accurate, readily available, and radiation-free technique to quantify intra-abdominal fat in adults, but its use in children has not yet been validated. Computed tomography (CT) is a reliable tool to assess body composition, but its use in children should be avoided due to the significant radiation burden. Quantitative Magnetic Resonance Imaging (qMRI) provides an accurate measurement of body composition, through the quantification of the visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and brown adipose tissue (BAT), as well as lean mass. Furthermore, qMRI provides other significant estimates such as the Proton Density Fat-Fraction of the fat tissue. This review article aims to briefly describe the state of art of the advanced imaging techniques to provide a quantitative assessment of body composition in children and adolescents.

Bone marrow fat: friend or foe in people with diabetes mellitus?

Global trends in the prevalence of overweight and obesity put the adipocyte in the focus of huge medical interest. This review highlights a new topic in adipose tissue biology, namely the emerging pathogenic role of fat accumulation in bone marrow (BM). Specifically, we summarize current knowledge about the origin and function of BM adipose tissue (BMAT), provide evidence for the association of excess BMAT with diabetes and related cardiovascular complications, and discuss potential therapeutic approaches to correct BMAT dysfunction. There is still a significant uncertainty about the origins and function of BMAT, although several subpopulations of stromal cells have been suggested to have an adipogenic propensity. BM adipocytes are higly plastic and have a distinctive capacity to secrete adipokines that exert local and endocrine functions. BM adiposity is abundant in elderly people and has therefore been interpreted as a component of the whole-body ageing process. BM senescence and BMAT accumulation has been also reported in patients and animal models with Type 2 diabetes, being more pronounced in those with ischaemic complications. Understanding the mechanisms responsible for excess and altered function of BMAT could lead to new treatments able to preserve whole-body homeostasis.

Association of Dimethylguanidino Valeric Acid With Partial Resistance to Metabolic Health Benefits of Regular Exercise

Importance

Metabolic responses to exercise training are variable. Metabolite profiling may aid in the clinical assessment of an individual's responsiveness to exercise interventions.

Objective

To investigate the association between a novel circulating biomarker of hepatic fat, dimethylguanidino valeric acid (DMGV), and metabolic health traits before and after 20 weeks of endurance exercise training.

Design, Setting, and Participants

This study involved cross-sectional and longitudinal analyses of the Health, Risk Factors, Exercise Training, and Genetics (HERITAGE) Family Study, a 20-week, single-arm endurance exercise clinical trial performed in multiple centers between 1993 and 1997. White participants with sedentary lifestyles who were free of cardiometabolic disease were included. Metabolomic tests were performed using a liquid chromatography, tandem mass spectrometry method on plasma samples collected before and after exercise training in the HERITAGE study. Metabolomics and data analysis were performed from August 2017 to May 2018.

Exposures

Plasma DMGV levels.

Main Outcome and Measures

The association between DMGV levels and measures of body composition, plasma lipids, insulin, and glucose homeostasis before and after exercise training.

Results

Among the 439 participants included in analyses from HERITAGE, the mean (SD) age was 36 (15) years, 228 (51.9%) were female, and the median (interquartile range) body mass index was 25 (22-28). Baseline levels of DMGV were positively associated with body fat percentage, abdominal visceral fat, very low-density lipoprotein cholesterol, and triglycerides, and inversely associated with insulin sensitivity, low-density lipoprotein cholesterol, high-density lipoprotein size, and high-density lipoprotein cholesterol (range of β coefficients, 0.17-0.46 [SEs, 0.026-0.050]; all P < .001, after adjusting for age and sex). After adjusting for age, sex, and baseline traits, baseline DMGV levels were positively associated with changes in small high-density lipoprotein particles (β, 0.14 [95% CI, 0.05-0.23]) and inversely associated with changes in medium and total high-density lipoprotein particles (β, -0.15 [95% CI, -0.24 to -0.05] and -0.19 [95% CI, -0.28 to -0.10], respectively), apolipoprotein A1 (β, -0.14 [95% CI, -0.23 to -0.05]), and insulin sensitivity (β, -0.13; P = 3.0 × 10-3) after exercise training.

Conclusions and Relevance

Dimethylguanidino valeric acid is an early marker of cardiometabolic dysfunction that is associated with attenuated improvements in lipid traits and insulin sensitivity after exercise training. Levels of DMGV may identify individuals who require additional therapies beyond guideline-directed exercise to improve their metabolic health.

Metabolically Healthy Obesity and Bariatric Surgery

A peculiar category of persons with obesity lacking common metabolic disturbances has been depicted and termed as metabolically healthy obesity (MHO). Yet, although MHO patients are free of obesity-associated complications, they might not be entirely precluded from developing cardio-metabolic disorders. Among patients with morbid obesity (MO) who are referred to bariatric surgery, a subset of metabolically healthy MO (MHMO) has been identified and the question arises if these patients would benefit from surgery in terms of mitigating the peril of cardio-metabolic complications. We revisited the pathophysiological mechanisms that define MHO, the currently available data on the cardio-metabolic risk of these patients and finally we reviewed the benefits of bariatric surgery and the urge to better characterize MHMO before submission to surgery.

Circulating Biomarker Score for Visceral Fat and Risks of Incident Colorectal and Postmenopausal Breast Cancer: The Multiethnic Cohort Adiposity Phenotype Study

BACKGROUND

Visceral adipose tissue (VAT) may play a greater role than subcutaneous fat in increasing cancer risk but is poorly estimated in epidemiologic studies.

METHODS

We developed a VAT prediction score by regression equations averaged across 100 least absolute shrinkage and selection operator models in a cross-sectional study of 1,801 older adults in the Multiethnic Cohort (MEC). The score was then used as proxy for VAT in case-control studies of postmenopausal breast (950 case-control pairs) and colorectal (831 case-control pairs) cancer in an independent sample in MEC. Abdominal MRI-derived VAT; circulating biomarkers of metabolic, hormonal, and inflammation dysfunctions; and ORs for incident cancer adjusted for BMI and other risk factors were assessed.

RESULTS

The final score, composed of nine biomarkers, BMI, and height, explained 11% and 15% more of the variance in VAT than BMI alone in men and women, respectively. The area under the receiver operator curve for VAT >150 cm² was 0.90 in men and 0.86 in women. The VAT score was associated with risk of breast cancer [OR (95% confidence interval [CI]) by increasing tertiles: 1.00, 1.09 (0.86-1.39), 1.48 (1.16-1.89); P _trend = 0.002] but not with colorectal cancer (P = 0.84), although an association [1.00, 0.98 (0.68-1.39), 1.24 (0.88-1.76); P _trend = 0.08] was suggested for this cancer after excluding cases that occurred within 7 years of blood draw (P _{heterogeneity} = 0.06).

CONCLUSIONS

The VAT score predicted risks of postmenopausal breast cancer and can be used for risk assessment in diverse populations.

IMPACT

These findings provide specific evidence for a role of VAT in breast cancer.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.

Excessive Weight Gain Before and During Gestational Diabetes Mellitus Management: What Is the Impact?

OBJECTIVE

Conventional gestational diabetes mellitus (GDM) management focuses on managing blood glucose in order to prevent adverse outcomes. We hypothesized that excessive weight gain at first presentation with GDM (excessive gestational weight gain [EGWG]) and continued EGWG (cEGWG) after commencing GDM management would increase the risk of adverse outcomes, despite treatment to optimize glycemia.

RESEARCH DESIGN AND METHODS

Data collected prospectively from pregnant women with GDM at a single institution were analyzed. GDM was diagnosed on the basis of Australasian Diabetes in Pregnancy Society 1998 guidelines (1992-2015). EGWG means having exceeded the upper limit of the Institute of Medicine-recommended target ranges for the entire pregnancy, by GDM presentation. The relationship between EGWG and antenatal 75-g oral glucose tolerance test (oGTT) values and adverse outcomes was evaluated. Relationships were examined between cEGWG, insulin requirements, and large-for-gestational-age (LGA) infants.

RESULTS

Of 3,281 pregnant women, 776 (23.6%) had EGWG. Women with EGWG had higher mean fasting plasma glucose (FPG) on oGTT (5.2 mmol/L [95% CI 5.1-5.3] vs. 5.0 mmol/L [95% CI 4.9-5.0]; P < 0.01), after adjusting for confounders, and more often received insulin therapy (47.0% vs. 33.6%; P < 0.0001), with an adjusted odds ratio (aOR) of 1.4 (95% CI 1.1-1.7; P < 0.01). aORs for each 2-kg increment of cEGWG were a 1.3-fold higher use of insulin therapy (95% CI 1.1-1.5; P < 0.001), an 8-unit increase in final daily insulin dose (95% CI 5.4-11.0; P < 0.0001), and a 1.4-fold increase in the rate of delivery of LGA infants (95% CI 1.2-1.7; P < 0.0001).

CONCLUSIONS

The absence of EGWG and restricting cEGWG in GDM have a mitigating effect on oGTT-based FPG, the risk of having an LGA infant, and insulin requirements.

Sphingolipids in Obesity and Correlated Co-Morbidities: The Contribution of Gender, Age and Environment

This paper reviews our present knowledge on the contribution of ceramide (Cer), sphingomyelin (SM), dihydroceramide (DhCer) and sphingosine-1-phosphate (S1P) in obesity and related co-morbidities. Specifically, in this paper, we address the role of acyl chain composition in bodily fluids for monitoring obesity in males and females, in aging persons and in situations of environmental hypoxia adaptation. After a brief introduction on sphingolipid synthesis and compartmentalization, the node of detection methods has been critically revised as the node of the use of animal models. The latter do not recapitulate the human condition, making it difficult to compare levels of sphingolipids found in animal tissues and human bodily fluids, and thus, to find definitive conclusions. In human subjects, the search for putative biomarkers has to be performed on easily accessible material, such as serum. The serum “sphingolipidome” profile indicates that attention should be focused on specific acyl chains associated with obesity, per se, since total Cer and SM levels coupled with dyslipidemia and vitamin D deficiency can be confounding factors. Furthermore, exposure to hypoxia indicates a relationship between dyslipidemia, obesity, oxygen level and aerobic/anaerobic metabolism, thus, opening new research avenues in the role of sphingolipids.

Placental expressions and serum levels of adiponectin, visfatin, and omentin in GDM

AIMS

Adiponectin, visfatin, and omentin have been shown to be associated with insulin sensitivity and might have a role in the pathophysiology of gestational diabetes mellitus (GDM). This study aimed to (1) compare adiponectin, visfatin, and omentin mRNA expressions in placenta and their serum levels between normal pregnancy (NP) and GDM class A1 (GDMA1) pregnancy and (2) determine correlations between placental gene expressions as well as serum levels with maternal and neonatal clinical parameters in all, NP, and GDM subjects.

METHODS

NP subjects (n = 37), who had normal medical history during their pregnancies without diagnosis of any abnormalities and GDMA1 subjects (n = 37), who were diagnosed since they had antenatal care, were recruited when they were in labor with a gestational age of at least 34 weeks. Clinical parameters and serum adiponectin, visfatin, and omentin levels were measured in the delivery room.

RESULTS

GDMA1 subjects had higher serum visfatin and plasma glucose levels, but lower serum omentin levels (p  < 0.05 all) compared to controls, with comparable levels of placental adiponectin, visfatin, and omentin expressions, plasma insulin, and indices of insulin sensitivity and insulin resistance. Serum visfatin was negatively correlated with neonatal weight and length in the GDM group (p  < 0.05 all). Serum omentin was negatively correlated with pre-pregnancy body mass index and waist circumference only in the NP group (p  < 0.05 all). Serum adiponectin was negatively correlated with maternal age and HOMA-IR in the NP group (p  < 0.05 all) and with placental weight and serum omentin in the GDM group (p  < 0.05 all).

CONCLUSIONS

In conclusion, in GDMA1, increased serum visfatin, which has insulin-mimetic effect, might be associated with a compensatory mechanism that improves the impaired insulin function. Decreased serum omentin in GDMA1, which is normally found in visceral obesity, might lead to insulin resistance and contribute to the pathophysiology of GDM.

New Insights into the Liver-Visceral Adipose Axis During Hepatic Resection and Liver Transplantation

In the last decade, adipose tissue has emerged as an endocrine organ with a key role in energy homeostasis. In addition, there is close crosstalk between the adipose tissue and the liver, since pro- and anti-inflammatory substances produced at the visceral adipose tissue level directly target the liver through the portal vein. During surgical procedures, including hepatic resection and liver transplantation, ischemia–reperfusion injury induces damage and regenerative failure. It has been suggested that adipose tissue is associated with both pathological or, on the contrary, with protective effects on damage and regenerative response after liver surgery. The present review aims to summarize the current knowledge on the crosstalk between the adipose tissue and the liver during liver surgery. Therapeutic strategies as well as the clinical and scientific controversies in this field are discussed. The different experimental models, such as lipectomy, to evaluate the role of adipose tissue in both steatotic and nonsteatotic livers undergoing surgery, are described. Such information may be useful for the establishment of protective strategies aimed at regulating the liver–visceral adipose tissue axis and improving the postoperative outcomes in clinical liver surgery.

Hyperinsulinemia: An Early Indicator of Metabolic Dysfunction

Hyperinsulinemia is strongly associated with type 2 diabetes. Racial and ethnic minority populations are disproportionately affected by diabetes and obesity-related complications. This mini-review provides an overview of the genetic and environmental factors associated with hyperinsulinemia with a focus on racial and ethnic differences and its metabolic consequences. The data used in this narrative review were collected through research in PubMed and reference review of relevant retrieved articles. Insulin secretion and clearance are regulated processes that influence the development and progression of hyperinsulinemia. Environmental, genetic, and dietary factors are associated with hyperinsulinemia. Certain pharmacotherapies for obesity and bariatric surgery are effective at mitigating hyperinsulinemia and are associated with improved metabolic health. Hyperinsulinemia is associated with many environmental and genetic factors that interact with a wide network of hormones. Recent studies have advanced our understanding of the factors affecting insulin secretion and clearance. Further basic and translational work on hyperinsulinemia may allow for earlier and more personalized treatments for obesity and metabolic diseases.

Endoplasmic reticulum stress: A master regulator of metabolic syndrome

Endoplasmic reticulum (ER) stress, a change in the ER homeostasis, leads to initiation of the unfolded protein response (UPR). The primary functions of the UPR are to restore the ER's physiological activity and coordinate the apoptotic and adaptive responses. Pathophysiological conditions that augment ER stress include hypoxia, misfolded and/or mutated protein accumulation, and high glucose. Prolonged ER stress is a critical factor in the pathogenesis of metabolic syndrome including type 2 diabetes mellitus, cardiovascular diseases, atherosclerosis, obesity, and fatty liver disease. UPR is a complex homeostatic pathway between newly synthesized proteins and their maturation, although the regulatory mechanisms contributing to the UPR and the possible therapeutic strategies are yet to be clarified. Therefore, a comprehensive understanding of the underlying molecular mechanisms is necessary to develop therapeutic interventions targeting ER stress response. In this review, we discuss the role of ER stress and UPR signaling in the pathogenesis of metabolic syndrome, highlighting the main functions of UPR components. We have emphasized the use of novel small molecular chemical chaperones, considered as modulators of ER stress. The initial studies with these chemical chaperones are promising, but detailed studies are required to define their efficacy and adverse effects during therapeutic use in humans.

MicroRNA-351 eases insulin resistance and liver gluconeogenesis via the PI3K/AKT pathway by inhibiting FLOT2 in mice of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is known as different degree glucose intolerance that is initially identified during pregnancy. MicroRNAs (miRs) may be a potential candidate for treatment of GDM. Herein, we suggested that miR‐351 could be an inhibitor in the progression of GDM via the phosphoinositide 3‐kinase/protein kinase B (PI3K/AKT) pathway. Microarray analysis was used to identify differentially expressed genes and predict miRs regulating flotillin 2 (FLOT2). Target relationship between miR‐351 and FLOT2 was verified. Gestational diabetes mellitus mice were treated with a series of mimic, inhibitor and small interfering RNA to explore the effect of miR‐351 on insulin resistance (IR), cell apoptosis in pancreatic tissues and liver gluconeogenesis through evaluating GDM‐related biochemical indexes, as well as expression of miR‐351, FLOT2, PI3K/AKT pathway‐, IR‐ and liver gluconeogenesis‐related genes. MiR‐351 and FLOT2 were reported to be involved in GDM. FLOT2 was the target gene of miR‐351. Gestational diabetes mellitus mice exhibited IR and liver gluconeogenesis, up‐regulated FLOT2, activated PI3K/AKT pathway and down‐regulated miR‐351 in liver tissues. Additionally, miR‐351 overexpression and FLOT2 silencing decreased the levels of FLOT2, phosphoenolpyruvate carboxykinase, glucose‐6‐phosphatase, fasting blood glucose, fasting insulin, total cholesterol, triglyceride, glyeosylated haemoglobin and homeostasis model of assessment for IR index (HOMA‐IR), extent of PI3K and AKT phosphorylation, yet increased the levels of HOMA for islet β‐cell function, HOMA for insulin sensitivity index and glucose transporter 2 expression, indicating reduced cell apoptosis in pancreatic tissues and alleviated IR and liver gluconeogenesis. Our results reveal that up‐regulation of miR‐351 protects against IR and liver gluconeogenesis by repressing the PI3K/AKT pathway through regulating FLOT2 in GDM mice, which identifies miR‐351 as a potential therapeutic target for the clinical management of GDM.