The portal theory supported by venous drainage-selective fat transplantation

Enhancing adipose tissue plasticity: progenitor cell roles in metabolic health

Adipose tissue demonstrates considerable plasticity and heterogeneity, enabling metabolic, cellular and structural adaptations to environmental signals. This adaptability is key for maintaining metabolic homeostasis. Impaired adipose tissue plasticity can lead to abnormal adipose tissue responses to metabolic cues, which contributes to the development of cardiometabolic diseases. In chronic obesity, white adipose tissue undergoes pathological remodelling marked by adipocyte hypertrophy, chronic inflammation and fibrosis, which are linked to local and systemic insulin resistance. Research data suggest that the capacity for healthy or unhealthy white adipose tissue remodelling might depend on the intrinsic diversity of adipose progenitor cells (APCs), which sense and respond to metabolic cues. This Review highlights studies on APCs as key determinants of adipose tissue plasticity, discussing differences between subcutaneous and visceral adipose tissue depots during development, growth and obesity. Modulating APC functions could improve strategies for treating adipose tissue dysfunction and metabolic diseases in obesity.

Pancreatic β-cell Function is Higher in Morning Versus Intermediate Chronotypes With Obesity

Objectives

People with later chronotypes are at greater T2D risk, yet it is unknown if β-cell function differs among chronotypes. Thus we, assessed β-cell function in morning (MORN) and intermediate (INT) chronotypes with obesity.

Methods

Adults (n = 41, 9M, 55 ± 1.7 y, 36.8 ± 1.0 kg/m2) were grouped as MORN or INT per the Morningness-Eveningness Questionnaire. Glucose, insulin, C-peptide, GIP, and GLP-1(active) were collected every 30 min during a 120 min 75g-OGTT. Insulin secretion rates (ISR) were calculated (regularized deconvolution) to assess early (total area under the curve; tAUC0-30min) and total-phase (tAUC0-120min) glucose-stimulated insulin secretion (GSIS:ISR/Glucose). Skeletal muscle (glucose infusion rate/steady-state insulin) insulin sensitivity and hepatic (HOMA-IR) as well as adipose (Adipose-IR) insulin resistance were assessed during a 120 min euglycemic hyperinsulinemic clamp (40mU/m2/min, 90 mg/dL). β-cell function (disposition index (DI): GSIS adjusted insulin sensitivity) was determined. Body composition (DXA) and fitness (VO2max) were also measured.

Results

Age, body composition and VO2max were similar between groups, but INT had reduced muscle insulin sensitivity and higher hepatic and adipose IR (p < 0.05). INT had higher C-peptide tAUC0-30min (p = 0.04) and lower hepatic DI (tAUC0-30min p = 0.05 and tAUC0-120min p = 0.07, respectively). Early phase hepatic DI correlated with GLP-1 tAUC0-30min (r = 0.35, p < 0.02) and tAUC0-120min (r = -0.40, p = 0.04).

Conclusions

β-cell function was higher in MORN versus INT chronotypes. Further work is warranted to discern how chronotype impacts insulin secretion.

Trial Registration

NCT03355469.

Purple potato extract modulates fat metabolizing genes expression, prevents oxidative stress, hepatic steatosis, and attenuates high-fat diet-induced obesity in male rats

OBJECTIVE

In this investigation, the significance of purple potato (Solanum tuberosum L.) extract treatment was assessed against oxidative stress and fat metabolizing transcription factors in the liver of high-fat (HF) diet-fed rats.

METHODS

Wistar (male) rats were arranged into several groups and provided with a control and HF diet along with the purple potato extract. Body weights, oral glucose tolerance test (OGTT), insulin, plasma lipids, and oxidative stress-related indicators were analyzed in plasma and tissue samples. Additionally, real-time PCR was performed to evaluate the gene expression for oxidative stress and fat metabolism in the liver. Histological staining was also performed on pancreatic and hepatic tissues.

RESULTS

Purple potato extract lowered body weights and improved glucose utilization in the OGTT test in HF diet-fed rats. Purple potato extract also suppressed HF-diet-induced oxidative stress in plasma and hepatic tissues. Purple potato extract also restored the Nrf-2 expression in the liver, followed by the improved expression of HO-1, HO-2, and other antioxidant genes in HF diet-fed rats. In addition, genes involved in lipid metabolism were also positively modulated due to purple potato extract treatment. Furthermore, histological examination revealed the reduction of lipid accumulation and amelioration of inflammation due to the consumption of purple potato extract.

CONCLUSION

This investigation revealed that antioxidant-rich purple potato extract can modulate the antioxidant and fat metabolizing genes expression, ameliorated oxidative stress and glucose intolerance as well as lowered blood lipids in male rats.

Sustainable Utilization of Coffee Pulp, a By-Product of Coffee Production: Effects on Metabolic Syndrome in Fructose-Fed Rats

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities that include insulin resistance, impaired glucose tolerance, dyslipidemia, hypertension, and abdominal obesity. Coffee production generates large quantities of waste products, which pose a serious threat to the environment. However, coffee by-products, such as coffee pulp (CP), possess an undeniable wealth of bioactive components. Based on this, we investigated whether a 10-week dietary intervention with 250 mg/kg/d of CP could prevent or ameliorate MetS in high-fructose-fed rats. Consumption of CP by rats fed a high-fructose diet reduced body weight gain, lowered systolic blood pressure (SBP), fasting plasma glucose and insulin levels, and improved insulin resistance compared to rats fed a high-fructose diet alone. At the hepatic level, CP attenuated the increase in lipid storage, reduced lipid peroxidation, and improved glutathione levels when combined with a high-fructose diet. CP also affected the expression of key genes related to glucose and lipid metabolism in hepatic and adipose tissues, in rats fed a fructose-rich diet. This study demonstrates that CP ameliorates several consequences of high-fructose-induced MetS in the rat (weight gain, hypertension, glucose intolerance, insulin resistance, changes in liver, and adipose tissue function). Hence, our data provide evidence that CP consumption in the context of a high-fructose diet can be used to improve MetS management.

Prediabetes remission to reduce the global burden of type 2 diabetes

Prediabetes is a highly prevalent and increasingly common condition affecting a significant proportion of the global population. The heterogeneous nature of prediabetes presents a challenge in identifying individuals who particularly benefit from lifestyle or other therapeutic interventions aiming at preventing type 2 diabetes (T2D) and associated comorbidities. The phenotypic characteristics of individuals at risk for diabetes are associated with both specific risk profiles for progression and a differential potential to facilitate prediabetes remission and reduce the risk of future T2D. This review examines the current definition and global prevalence of prediabetes and evaluates the potential of prediabetes remission to reduce the alarming increase in the global burden of T2D.

Visceral adipose tissue area and proportion provide distinct reflections of cardiometabolic outcomes in weight loss; pooled analysis of MRI-assessed CENTRAL and DIRECT PLUS dietary randomized controlled trials

BACKGROUND

Visceral adipose tissue (VAT) is well established as a pathogenic fat depot, whereas superficial subcutaneous adipose tissue (SAT) is associated with either an improved or neutral cardiovascular state. However, it is unclear to what extent VAT area (VATcm2) and its proportion of total abdominal adipose tissue (VAT%) are distinguished in predicting cardiometabolic status and clinical outcomes during weight loss.

METHODS

We integrated magnetic resonance imaging (MRI) measurements of VAT, deep-SAT, and superficial-SAT from two 18-month lifestyle weight loss clinical trials, CENTRAL and DIRECT PLUS (n = 572).

RESULTS

At baseline, the mean VATcm2 was 144.8cm2 and VAT% = 28.2%; over 18 months, participants lost 28cm2 VATcm2 (- 22.5%), and 1.3 VAT% units. Baseline VATcm2 and VAT% were similarly associated with metabolic syndrome, hypertension, and diabetes status, while VAT% better classified hypertriglyceridemia. Conversely, higher VATcm2 was associated with elevated high-sensitivity C-reactive protein (hsCRP), while VAT% was not. After 18 months of lifestyle intervention, both VATcm2 and VAT% loss were significantly associated with decreased triglycerides, HbA1c, ferritin, and liver enzymes, and increased HDL-c levels beyond weight loss (FDR < 0.05). Only VATcm2 loss was correlated with decreased HOMA-IR, chemerin, and leptin levels.

CONCLUSIONS

MRI follow-up of 572 participants over 18 months of weight loss intervention suggests that although increased VATcm2 and VAT% exhibit similar clinical manifestations, it might be preferable to examine VAT% when exploring lipid status, while VATcm2 may better reflect inflammatory and glycemic states.

TRIAL REGISTRATION

CENTRAL (Clinical-trials-identifier: NCT01530724); DIRECT PLUS (Clinical-trials-identifier: NCT03020186).

Immune Regulatory Crosstalk in Adipose Tissue Thermogenesis

Brown adipose tissue (BAT) and thermogenic beige fat within white adipose tissue (WAT), collectively known as adaptive thermogenic fat, dissipate energy as heat, offering promising therapeutic potential to combat obesity and metabolic disorders. The specific biological functions of these fat depots are determined by their unique interaction with the microenvironments, composed of immune cells, endothelial cells, pericytes, and nerve fibers. Immune cells residing in these depots play a key role in regulating energy expenditure and systemic energy homeostasis. The dynamic microenvironment of thermogenic fat depots is essential for maintaining tissue health and function. Immune cells infiltrate both BAT and beige WAT, contributing to their homeostasis and activation through intricate cellular communications. Emerging evidence underscores the importance of various immune cell populations in regulating thermogenic adipose tissue, though many remain undercharacterized. This review provides a comprehensive overview of the immune cells that regulate adaptive thermogenesis and their complex interactions within the adipose niche, highlighting their potential to influence metabolic health and contribute to therapeutic interventions for obesity and metabolic syndrome.

Metabolic profiles in early pregnancy associated with metabolic pregnancy complications in women with obesity

INTRODUCTION

Higher maternal body mass index (BMI) is associated with metabolic disturbances and pregnancy complications. We aimed to examine whether metabolic profiles in early pregnancy were associated with metabolic pregnancy complications in women with obesity (BMI ≥ 30 kg/m2).

MATERIAL AND METHODS

Nested cohort study from a prospective longitudinal cohort (n = 1031) of women who were healthy prior to pregnancy and gave birth at Oslo University Hospital from 2002-2008. The sample comprised 81 women with obesity. Metabolic pregnancy complications included gestational diabetes mellitus, gestational hypertension and preeclampsia. In plasma samples from gestational weeks 14-16, 91 metabolites were analyzed by nuclear magnetic resonance spectroscopy. We performed a principal component analysis to reduce the metabolic dimensions. Logistic regression models were fitted to estimate crude and adjusted odds ratios (ORs) of metabolic pregnancy complications.

RESULTS

Twenty-four out of 81 women developed metabolic pregnancy complications (gestational hypertension, preeclampsia, and/or gestational diabetes). Two of five principal components (80 % explained variance) were significantly associated with metabolic pregnancy complications. The ratio of monounsaturated to total fatty acids increased the risk of metabolic pregnancy complications (OR 2.09, 95 % confidence interval [CI] 1.25-3.75), while the ratio of polyunsaturated to monounsaturated fatty acids decreased the risk (OR 0.54, 95 % CI 0.30-0.89). The ratio of omega-3 to total fatty acids (OR 0.59, 95 % CI 0.34-0.98) and the ratio of docosahexaenoic acid to total fatty acids (OR 0.57, 95 % CI 0.31-0.97) also decreased the risk of metabolic pregnancy complications.

CONCLUSION

Metabolic profile in early pregnancy was associated with risk of metabolic pregnancy complications in women with obesity. We observed the strongest associations between fatty acid composition and metabolic pregnancy complications.

The Role of Lymph-Adipose Crosstalk in Alcohol-Induced Perilymphatic Adipose Tissue Dysfunction

Chronic alcohol use leads to metabolic dysfunction in adipose tissue. The underlying mechanisms and the contribution of alcohol-induced adipose tissue dysfunction to systemic metabolic dysregulation are not well understood. In our previous studies, we found that chronic alcohol feeding induces mesenteric lymphatic leakage, perilymphatic adipose tissue (PLAT) inflammation, and local insulin resistance in rats. The goal of this study was to further explore the link between alcohol-induced lymphatic leakage and PLAT immunometabolic dysregulation, locally and systemically, using in vivo and ex vivo approaches. Male rats received a Lieber-DeCarli liquid diet, of which 36% of the calories were from alcohol, for 10 weeks. Time-matched control animals were pair-fed. Adipokine levels were measured in PLAT, subcutaneous fat, plasma, and mesenteric lymph samples. Glucose tolerance was assessed after 10 weeks. Further, we used a novel ex vivo lymph-stimulated naïve PLAT explant approach to modeling lymph leakage to assess changes in adipokine secretion and expression of proinflammatory markers after stimulation with lymph from alcohol- or pair-fed animals. Our data show that chronic alcohol-fed rats presented PLAT-specific decreases in adiponectin and leptin levels, alterations in the expression of genes involved in lipid metabolic pathways, and associated impaired whole-body glucose homeostasis. Further, we found that direct naïve PLAT stimulation with lymph contents from alcohol-fed animals increased IL-6 expression in demonstrating the ability of lymph contents to differentially impact naïve adipose tissue. Overall, chronic alcohol feeding leads to depot-specific alterations in metabolic profile, impaired systemic glucose tolerance, and lymph-induced adipose tissue inflammation. The specific lymph components leading to PLAT immunometabolic dysregulation remain to be determined.

Targeting the Epigenetic Marks in Type 2 Diabetes Mellitus: Will Epigenetic Therapy Be a Valuable Adjunct to Pharmacotherapy?

Although genetic, environmental, and lifestyle factors largely contribute to type 2 diabetes mellitus (T2DM) risk, the role of epigenetics in its pathogenesis is now well established. The epigenetic mechanisms in T2DM mainly consist of DNA methylation, histone modifications and regulation by noncoding RNAs (ncRNAs). For instance, DNA methylation at CpG islands in the promoter regions of specific genes encoding insulin signaling and glucose metabolism suppresses these genes. Modulating the enzyme mediators of these epigenetic marks aims to restore standard gene expression patterns and improve glycemic control. In targeting these epigenetic marks, using epigenetic drugs such as DNA methyltransferase (DNAMT), histone deacetylase (HDAC) and histone acetyltransferase (HAT) inhibitors has led to variable success in humans and experimental murine models. Specifically, the United States' Food and Drug Administration (US FDA) has approved DNAMT inhibitors like 5-azacytidine and 5-aza-2'-deoxycytidine for use in diabetic retinopathy: a T2DM microvascular complication. These DNAMT inhibitors block the genes for methylation of mitochondrial superoxide dismutase 2 (SOD2) and matrix metallopeptidase 9 (MMP-9): the epigenetic marks in diabetic retinopathy. Traditional pharmacotherapy with metformin also have epigenetic effects in T2DM and positively alter disease outcomes when combined with epigenetic drugs like DNAMT and HDAC inhibitors, raising the prospect of using epigenetic therapy as a valuable adjunct to pharmacotherapy. However, introducing small interfering RNAs (siRNAs) in cells to silence specific target genes remains in the exploratory phase. Future research should focus on regulating gene expression in T2DM using long noncoding RNA (lncRNA) molecules, another type of ncRNA. This review discusses the epigenetics of T2DM and that of its macro- and microvascular complications, and the potential benefits of combining epigenetic therapy with pharmacotherapy for optimal results.

A clinician's perspective on the new organ mesentery and non-vascular mesenteropathies

Mesentery was discovered as a new organ in 2017. It is a continuous membranous tissue from the duodenojejunal flexure to the anorectal junction. It has distinct anatomy, physiology, and disease states. Primary mesenteropathies include vascular and non-vascular diseases. Some of them are common, and some of them are rarely seen in clinical practice. Secondary mesenteropathies occur when infection or malignancy in another organ spreads to the mesentery. Each entity has specific diagnostic and treatment protocols. Increased awareness of different mesenteropathies and an understanding of their various presentations at different stages of life can help in early diagnosis and improved clinical outcomes.

Rab18 maintains homeostasis of subcutaneous adipose tissue to prevent obesity-induced metabolic disorders

Metabolically healthy obesity refers to obese individuals who do not develop metabolic disorders. These people store fat in subcutaneous adipose tissue (SAT) rather than in visceral adipose tissue (VAT). However, the molecules participating in this specific scenario remain elusive. Rab18, a lipid droplet (LD)-associated protein, mediates the contact between the endoplasmic reticulum (ER) and LDs to facilitate LD growth and maturation. In the present study, we show that the protein level of Rab18 is specifically upregulated in the SAT of obese people and mice. Rab18 adipocyte-specific knockout (Rab18 AKO) mice had a decreased volume ratio of SAT to VAT compared with wildtype mice. When subjected to high-fat diet (HFD), Rab18 AKO mice had increased ER stress and inflammation, reduced adiponectin, and decreased triacylglycerol (TAG) accumulation in SAT. In contrast, TAG accumulation in VAT, brown adipose tissue (BAT) or liver of Rab18 AKO mice had a moderate increase without ER stress stimulation. Rab18 AKO mice developed insulin resistance and systematic inflammation. Rab18 AKO mice maintained body temperature in response to acute and chronic cold induction with a thermogenic SAT, similar to the counterpart mice. Furthermore, Rab18-deficient 3T3-L1 adipocytes were more prone to palmitate-induced ER stress, indicating the involvement of Rab18 in alleviating lipid toxicity. Rab18 AKO mice provide a good animal model to investigate metabolic disorders such as impaired SAT. In conclusion, our studies reveal that Rab18 is a key and specific regulator that maintains the proper functions of SAT by alleviating lipid-induced ER stress.

White adipocyte dysfunction and obesity-associated pathologies in humans

The prevalence of obesity and associated chronic diseases continues to increase worldwide, negatively impacting on societies and economies. Whereas the association between excess body weight and increased risk for developing a multitude of diseases is well established, the initiating mechanisms by which weight gain impairs our metabolic health remain surprisingly contested. In order to better address the myriad of disease states associated with obesity, it is essential to understand adipose tissue dysfunction and develop strategies for reinforcing adipocyte health. In this Review we outline the diverse physiological functions and pathological roles of human white adipocytes, examining our current knowledge of why white adipocytes are vital for systemic metabolic control, yet poorly adapted to our current obesogenic environment.

Dawn-to-dusk dry fasting decreases circulating inflammatory cytokines in subjects with increased body mass index

BACKGROUND

The circadian rhythm involves numerous metabolic processes, including sleep/awakening, body temperature regulation, hormone secretion, hepatic function, cellular plasticity, and cytokine release (inflammation), that appear to have a dynamic relationship with all the processes above. Studies have linked various cytokines to the chronic state of low-grade inflammation and oxidative stress in obesity. Dawn-to-dusk dry fasting (DDDF) could alleviate the adverse effects of obesity by decreasing inflammation. This study examined the effects of DDDF on circulating inflammatory cytokines in subjects with increased body mass index (BMI).

METHODS

The current observational prospective study included adult subjects with a BMI equal to or greater than 25 kg/m2 who practiced the annual religious 30-day DDDF. Individuals with significant underlying medical conditions were excluded to limit confounding factors. All subjects were evaluated within two weeks before 30-day DDDF, within the fourth week of 30-day DDDF, and within two weeks after 30-day DDDF. Multiple cytokines and clinical health indicators were measured at each evaluation.

RESULTS

Thirteen subjects (10 men and three women) with a mean age of 32.9 years (SD = 9.7 years) and a mean BMI of 32 kg/m2 (SD = 4.6 kg/m2) were included. An overall associated decrease in the levels of multiple cytokines with DDDF was observed. A significant decrease in the mean interleukin 1 beta level was observed within the fourth week of 30-day DDDF (P = 0.045), which persisted even after the fasting period (P = 0.024). There was also a significant decrease in the mean levels of interleukin 15 (IL-15) (P = 0.014), interleukin 1 receptor antagonist (P = 0.041), macrophage-derived chemokine (MDC) (P = 0.013), and monokine induced by interferon gamma/chemokine (C-X-C motif) ligand 9 (P = 0.027) within the fourth week of 30-day DDDF and in the mean levels of fibroblast growth factor 2 (P = 0.010), interleukin 12 p40 subunit (P = 0.038), interleukin 22 (P = 0.025) and tumor necrosis factor alpha (P = 0.046) within two weeks after 30-DDDF. In terms of anthropometric parameters, there was a decrease in mean body weight (P = 0.032), BMI (P = 0.028), and hip circumference (P = 0.007) within the fourth week of 30-day DDDF and a decrease in mean weight (P = 0.026), BMI (P = 0.033) and hip circumference (P = 0.016) within two weeks after 30-day DDDF compared with the levels measured within two weeks before 30-day DDDF. Although there was no significant correlation between changes in weight and changes in circulating inflammatory cytokines, there was a significant positive correlation between changes in waist circumference and changes in specific inflammatory cytokines (e.g., IL-15, MDC, platelet-derived growth factor, soluble CD40L, vascular endothelial growth factor A) within the fourth week of 30-day DDDF and/or two weeks after 30-day DDDF. A significant decrease in mean average resting heart rate within the fourth week of 30-day DDDF was also observed (P = 0.023), and changes between average resting heart rate and changes in interleukin-8 levels within the fourth week of 30-day DDDF compared with baseline levels were positively correlated (r = 0.57, P = 0.042).

CONCLUSION

DDDF appears to be a unique and potent treatment to reduce low-grade chronic inflammation caused by obesity and visceral adiposity. Further studies with more extended follow-up periods are warranted to investigate the long-term anti-inflammatory benefits of DDDF in individuals with increased BMI.

Association between visceral obesity and tumor recurrence in hepatocellular carcinoma recipients undergoing liver transplantation

BACKGROUND

Excessive visceral obesity in recipients of living donor liver transplantation (LDLT) is associated with mortality, and a recent study reported the correlation between visceral adiposity of male LDLT recipients and hepatocellular carcinoma (HCC) recurrence. However, there is no study on the relationship between the donor's visceral adiposity and surgical outcomes in LDLT recipients. We investigated the association of the visceral-to-subcutaneous fat area ratio (VSR) in donors and recipients with HCC recurrence and mortality in LDLT.

METHODS

We analyzed 1386 sets of donors and recipients who underwent LDLT between January 2008 and January 2018. The maximal chi-square method was used to determine the optimal cutoff values for VSR for predicting overall HCC recurrence and mortality. Cox regression analyses were performed to evaluate the association of donor VSR and recipient VSR with overall HCC recurrence and mortality in recipients.

RESULTS

The cutoff values of VSR was determined as 0.73 in males and 0.31 in females. High donor VSR was significantly associated with overall HCC recurrence (adjusted hazard ratio [HR]: 1.43, 95% confidence interval [CI]: 1.06-1.93, p = 0.019) and mortality (HR: 1.35, 95% CI: 1.03-1.76, p = 0.030). High recipient VSR was significantly associated with overall HCC recurrence (HR: 1.40, 95% CI: 1.04-1.88, p = 0.027) and mortality (HR: 1.50, 95% CI: 1.14-1.96, p = 0.003).

CONCLUSIONS

Both recipient VSR and donor VSR were significant risk factors for HCC recurrence and mortality in LDLT recipients. Preoperative donor VSR and recipient VSR may be strong predictors of the surgical outcomes of LDLT recipients with HCC.

Bromocriptine and Colesevelam Hydrochloride: Novel Therapies for Type II Diabetes Mellitus

The increasing prevalence of type II diabetes mellitus (T2DM) is a worldwide healthcare concern. Over the years, our understanding of T2DM has grown considerably in uncovering the pathophysiology of the disease and, in turn, understanding how improved treatment methods can be used to slow disease progression. Some long-term complications that are responsible for most T2DM mortalities include cardiovascular disease, neurological decline, and renal failure. In treating T2DM, it is important that not only glycemic control be obtained but also control of associated complications. Bromocriptine and colesevelam hydrochloride have both been approved by the Food and Drug Administration (FDA) to treat T2DM but are not readily used in practice. These medications are known to treat glycemic dysregulation via unconventional mechanisms, which might contribute to their potential to provide protection against common diabetic complications such as cardiovascular disease. In order to ensure that these overlooked medications become more readily used, it is vital that more research be performed to further elucidate their efficacy in a clinical setting. Future studies should continue to provide clinicians a better understanding of the role these medications have on the treatment of T2DM such as their ability to be used in combination with other commonly used T2DM medications or as monotherapies.

Abdominal Obesity Genetic Variants Predict Waist Circumference Regain After Weight Loss

Although many individuals are able to achieve weight loss, maintaining this loss over time is challenging. We aimed to study whether genetic predisposition to general or abdominal obesity predicts weight regain after weight loss. We examined the associations between genetic risk scores for higher BMI and higher waist-to-hip ratio adjusted for BMI (WHRadjBMI) with changes in weight and waist circumference up to 3 years after a 1-year weight loss program in participants (n = 822 women, n = 593 men) from the Look AHEAD (Action for Health in Diabetes) study who had lost ≥3% of their initial weight. Genetic predisposition to higher BMI or WHRadjBMI was not associated with weight regain after weight loss. However, the WHRadjBMI genetic score did predict an increase in waist circumference independent of weight change. To conclude, a genetic predisposition to higher WHRadjBMI predicts an increase in abdominal obesity after weight loss, whereas genetic predisposition to higher BMI is not predictive of weight regain. These results suggest that genetic effects on abdominal obesity may be more pronounced than those on general obesity during weight regain.

ARTICLE HIGHLIGHTS

Nearly all individuals who intentionally lose weight experience weight regain. Individuals with a higher genetic risk for abdominal adiposity experience increased regain in waist circumference after weight loss. Genetic predisposition to higher BMI does not predict weight regain after weight loss.

Gluconeogenesis Flux in Metabolic Disease

Gluconeogenesis is a critical biosynthetic process that helps maintain whole-body glucose homeostasis and becomes altered in certain medical diseases. We review gluconeogenic flux in various medical diseases, including common metabolic disorders, hormonal imbalances, specific inborn genetic errors, and cancer. We discuss how the altered gluconeogenic activity contributes to disease pathogenesis using data from experiments using isotopic tracer and spectroscopy methodologies. These in vitro, animal, and human studies provide insights into the changes in circulating levels of available gluconeogenesis substrates and the efficiency of converting those substrates to glucose by gluconeogenic organs. We highlight ongoing knowledge gaps, discuss emerging research areas, and suggest future investigations. A better understanding of altered gluconeogenesis flux may ultimately identify novel and targeted treatment strategies for such diseases.

Association between visceral obesity and 10-year risk of first atherosclerotic cardiovascular diseases events among American adults: National Health and Nutrition Examination Survey

Background

In the United States, the relationship between visceral obesity and the risk of developing atherosclerosis cardiovascular disease (ASCVD) for the first time in 10 years is unclear.

Methods

Data for this cross-sectional study came from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2020. We collected variable information related to 10-year ASCVD risk and visceral obesity reliable indicators [Visceral obesity index (VAI) and Lipid accumulation product (LAP)]. And we used multiple logistic regression to analyze the correlation of visceral obesity indicators (VAI and LAP) with 10-year ASCVD risk. In addition, we assessed the linear relationship between VAI or LAP and 10-year ASCVD risk by smoothing curve fitting. Finally, we conducted subgroup analysis and sensitivity analysis after excluding participants with extreme VAI and LAP values to ensure that we obtained accurate and reliable results.

Results

Our study included a total of 1,547 participants (mean age: 56.5 ± 10.1, 60% of males). The results of the multiple logistic regression showed that compared with participants with the lowest VAI in the 1st Quartile (≤0.79), the adjusted OR values for VAI and elevated 10-year ASCVD risk in Q3 (1.30-2.14), and Q4 (≥2.15) were 2.58 (95% CI: 1.24-5.36, P = 0.011), 15.14 (95% CI: 6.93-33.05, P < 0.001), respectively. Compared with participants with the lowest LAP in the 1st Quartile (≤28.29), the adjusted OR values for VAI and elevated 10-year ASCVD risk in Q3 (46.52-77.00), and Q4 (≥77.01) were 4.63 (95% CI: 2.18-9.82, P < 0.001), 16.94 (95% CI: 6.74-42.57, P < 0.001), respectively. Stratified analysis showed that the association between VAI or LAP and the first ASCVD event was more pronounced in males.

Conclusion

Higher VAI or LAP scores are significantly associated with elevated 10-year ASCVD risk in adults aged 40 to 79 in the USA, which suggested that monitoring visceral obesity is crucial to reduce the risk of a first ASCVD event.

The Transcriptomic Landscape of Age-Induced Changes in Human Visceral Fat and the Predicted Omentum-Liver Connectome in Males

Aging causes alterations in body composition. Specifically, visceral fat mass increases with age and is associated with age-related diseases. The pathogenic potential of visceral fat accumulation has been associated with its anatomical location and metabolic activity. Visceral fat may control systemic metabolism by secreting molecules that act in distal tissues, mainly the liver, through the portal vein. Currently, little is known about age-related changes in visceral fat in humans. Aiming to identify molecular and cellular changes occurring with aging in the visceral fat of humans, we analyzed publicly available transcriptomic data of 355 omentum samples from the Genotype-Tissue Expression portal (GTEx) of 20-79-year-old males and females. We identified the functional enrichment of genes associated with aging, inferred age-related changes in visceral fat cellularity by deconvolution analysis, profiled the senescence-associated secretory phenotype of visceral adipose tissue, and predicted the connectivity of the age-induced visceral fat secretome with the liver. We demonstrate that age induces alterations in visceral fat cellularity, synchronous to changes in metabolic pathways and a shift toward a pro-inflammatory secretory phenotype. Furthermore, our approach identified candidates such as ADIPOQ-ADIPOR1/ADIPOR2, FCN2-LPR1, and TF-TFR2 to mediate visceral fat-liver crosstalk in the context of aging. These findings cast light on how alterations in visceral fat with aging contribute to liver dysfunction and age-related disease etiology.

Association of sex-specific donor skeletal muscle index with surgical outcomes in living donor liver transplantation recipients

BACKGROUND

A recent study reported a correlation between the muscle mass of male donors and graft failure in living donor liver transplantation (LDLT) recipients. We investigated the association of sex-specific donor skeletal muscle index (SMI) with mortality and graft failure in LDLT recipients.

METHODS

We retrospectively analysed 2750 sets of donors and recipients between January 2008 and January 2018. The recipient outcomes were analysed by dividing the data according to donor sex. Cox regression analyses were performed to evaluate the association between donor SMI by sex and 1-year mortality and graft failure in recipients.

RESULTS

In the male donor group, robust donor (increased SMI) was significantly associated with higher risks for mortality (hazard ratio [HR]: 1.03, 95% confidence interval [CI]: 1.00-1.06, p = .023) and graft failure (HR: 1.04, 95% CI: 1.01-1.06, p = .007) at 1 year. In the female donor group, the robust donor was significantly associated with lower risks for mortality (HR: 0.92, 95% CI: 0.87-0.97, p = .003) and graft failure (HR: 0.95, 95% CI: 0.90-1.00, p = .032) at 1 year.

CONCLUSIONS

Donor SMI was associated with surgical outcomes in recipients. Robust male and female donors were a significant negative and protective factor for grafts respectively.

From Beneath the Skin to the Airway Wall: Understanding the Pathological Role of Adipose Tissue in Comorbid Asthma-Obesity

This article provides a contemporary report on the role of adipose tissue in respiratory dysfunction. Adipose tissue is distributed throughout the body, accumulating beneath the skin (subcutaneous), around organs (visceral), and importantly in the context of respiratory disease, has recently been shown to accumulate within the airway wall: "airway-associated adipose tissue." Excessive adipose tissue deposition compromises respiratory function and increases the severity of diseases such as asthma. The mechanisms of respiratory impairment are inflammatory, structural, and mechanical in nature, vary depending on the anatomical site of deposition and adipose tissue subtype, and likely contribute to different phenotypes of comorbid asthma-obesity. An understanding of adipose tissue-driven pathophysiology provides an opportunity for diagnostic advancement and patient-specific treatment. As an exemplar, the potential impact of airway-associated adipose tissue is highlighted, and how this may change the management of a patient with asthma who is also obese. © 2023 American Physiological Society. Compr Physiol 13:4321-4353, 2023.

Of mice and men: Pinpointing species differences in adipose tissue biology

The prevalence of obesity and metabolic diseases continues to rise, which has led to an increased interest in studying adipose tissue to elucidate underlying disease mechanisms. The use of genetic mouse models has been critical for understanding the role of specific genes for adipose tissue function and the tissue’s impact on other organs. However, mouse adipose tissue displays key differences to human fat, which has led, in some cases, to the emergence of some confounding concepts in the adipose field. Such differences include the depot-specific characteristics of visceral and subcutaneous fat, and divergences in thermogenic fat phenotype between the species. Adipose tissue characteristics may therefore not always be directly compared between species, which is important to consider when setting up new studies or interpreting results. This mini review outlines our current knowledge about the cell biological differences between human and mouse adipocytes and fat depots, highlighting some examples where inadequate knowledge of species-specific differences can lead to confounding results, and presenting plausible anatomic explanations that may underlie the differences. The article thus provides critical insights and guidance for researchers working primarily with only human or mouse fat tissue, and may contribute to new ideas or concepts in the important and evolving field of adipose biology.

Metabolik sendromda visseral ve subkutan yağ miktari ve hepatosteatozun bilgisayarli tomografi ile kantitatif değerlendirilmesi

Purpose: We aimed to evaluate visceral and subcutaneous fat tissue and its association with hepatosteatosis on computed tomography (CT) scans to determine cut-off criteria for metabolic syndrome, measure abdominal obesity directly based on the visceral fat tissue area (VFTA) rather than indirectly based on waist circumference and obtain supportive findings by density measurements in addition to the VFTA measurements.Materials and Methods: The Hounsfield unit (HU) values, visceral, subcutaneous fat areas and HU values of 108 patients diagnosed with metabolic syndrome (MS) were determined according to the National Cholesterol Education Program Adult Treatment Panel III 2001 Criteria by retrospectively analyzing their abdominal CT images taken for various reasons. The relationships of the obtained values with each other and to MS were evaluated.Results: The strongest predictor of MS was VFTA, and 156.47 cm² was the most significant value with 74.1% sensitivity and 58.6% specificity. An HU value of -102.99 for visceral fat tissue density (VFTD) was found as the second most significant finding with 75% sensitivity and 57.6% specificity. The VFTA values of the patients with hepatosteatosis were higher, and increased VFTA values were associated with lower VFTD values.Conclusion: The most important supportive finding was the demonstration of the possibility of measuring abdominal obesity, which has an important place among criteria, directly by measuring VFTA, rather than indirectly based on waist circumference. 

It Is Not Just Fat: Dissecting the Heterogeneity of Adipose Tissue Function

PURPOSE OF REVIEW

The purpose of the current review is to summarize findings from the most recent and impactful studies which investigated human and mouse adipose tissue transcriptomes at a single-cell level. We provide perspective about the potential importance of data derived from these single-cell technologies in improving our understanding of the adipose organ and metabolic disease and likely future directions of this approach.

RECENT FINDINGS

The majority of single-cell or single-nuclei studies of the adipose organ so far have focused on investigating the stromal-vascular fraction (SVF) of mouse subcutaneous and intraabdominal white and interscapular brown fat depots. Few studies have also evaluated the impact of additional factors as drivers of adipose phenotypes, such as high-fat diet-induced obesity, adolescence, aging, and cold exposure. Recent studies have also investigated human cell lines and human fat biopsies across a range of body mass index (BMI) and in response to insulin resistance or T2D. These studies have identified numerous previously unexplored subpopulations of adipocyte progenitors, immune cells, and mature adipocytes in both mice and men. Single-cell and single-nuclei technologies have brought an explosion of data that have advanced our understanding of the adipose organ in health and disease. However, we are still at the dawn of achieving a complete and comprehensive map of the mouse and human adipose organ. Multi-modal single-cell approaches to identify both anatomic localization of specific cellular populations and epigenetic mechanisms responsible for observed transcriptomic patterns are underway and will likely provide an even deeper understanding of the adipose organ in response to health and disease.

WT1 in Adipose Tissue: From Development to Adult Physiology

Much of the fascination of the Wilms tumor protein (WT1) emanates from its unique roles in development and disease. Ubiquitous Wt1 deletion in adult mice causes multiple organ failure including a reduction of body fat. WT1 is expressed in fat cell progenitors in visceral white adipose tissue (WAT) but detected neither in energy storing subcutaneous WAT nor in heat producing brown adipose tissue (BAT). Our recent findings indicate that WT1 represses thermogenic genes and maintains the white adipose identity of visceral fat. Wt1 heterozygosity in mice is associated with molecular and morphological signs of browning including elevated levels of uncoupling protein 1 (UCP1) in epididymal WAT. Compared to their wild-type littermates, Wt1 heterozygous mice exhibit significantly improved whole-body glucose tolerance and alleviated hepatic steatosis under high-fat diet. Partial protection of heterozygous Wt1 knockout mice against metabolic dysfunction is presumably related to browning of their epididymal WAT. In the light of recent advancements, this article reviews the role of WT1 in the development of visceral WAT and its supposed function as a regulator of white adipose identity.

HOXA5-miR-574-5p axis promotes adipogenesis and alleviates insulin resistance

Differentiation of preadipocytes into functional adipocytes could be a major target for repressing obesity-induced insulin resistance (IR). However, the molecular mechanisms involved in adipogenesis and the development of IR are unclear. We report, for the first time, that miR-574-5p, a novel miRNA, promotes adipogenesis to suppress IR. An increase in the level of miR-574-5p significantly induced the differentiation of preadipocytes into mature adipocytes. Conversely, reduction of miR-574-5p levels blocked the differentiation of preadipocytes in vitro. In a dual-luciferase reporter assay, it was shown that homeobox A5 (HOXA5) promoted the transcription of miR-574-5p to induce the differentiation of preadipocytes. Hdac9, a direct downstream target of miR-574-5p, was involved in the regulation of adipocyte differentiation. The overexpression of miR-574-5p also promoted adipogenesis in subcutaneous fat to alleviate IR in high-fat-diet-fed mice. Additionally, miR-574-5p expression was significantly higher in the subcutaneous adipose tissue of obese patients without type 2 diabetes than in those with type 2 diabetes. There was an increase in HOXA5 expression and a decrease in histone deacetylase 9 (HDAC9) expression in the subcutaneous fat of obese patients without type 2 diabetes. These results suggest that miR-574-5p may be a potential therapeutic target for combating obesity-related IR.

Adipose-tissue plasticity in health and disease

Adipose tissue, colloquially known as "fat," is an extraordinarily flexible and heterogeneous organ. While historically viewed as a passive site for energy storage, we now appreciate that adipose tissue regulates many aspects of whole-body physiology, including food intake, maintenance of energy levels, insulin sensitivity, body temperature, and immune responses. A crucial property of adipose tissue is its high degree of plasticity. Physiologic stimuli induce dramatic alterations in adipose-tissue metabolism, structure, and phenotype to meet the needs of the organism. Limitations to this plasticity cause diminished or aberrant responses to physiologic cues and drive the progression of cardiometabolic disease along with other pathological consequences of obesity.

Association Between Visceral Adiposity Index and Insulin Resistance: A Cross-Sectional Study Based on US Adults

BACKGROUND

Visceral obesity index (VAI) is an empirical mathematical model used to evaluate the distribution and function of fat. Some studies have shown that VAI may be associated with the development of insulin resistance. In view of the differences in insulin resistance among different ethnic groups, this study attempts to analyze the special relationship between VAI and insulin resistance in American adults.

METHODS

We conducted a cross-sectional study through NHANES database. A total of 27309 patients over the age of 18 from the United States took part in the survey. It was divided into two groups: the IR-positive group and the IR-negative group. The association of VAI with IR was evaluated by logistic regression analyses mainly, including univariate analysis, multivariate regression analysis, curve fitting analysis and subgroup analysis.

RESULTS

The results showed that in the full-adjusted model, there is a strong positive association between VAI level and insulin resistance (OR: 1.28 (1.2~1.37), P<0.001) and there is a threshold effect.

CONCLUSIONS

This study suggests that higher VAI levels are associated with insulin resistance. VAI index may be used as a predictor of insulin resistance.

Mendelian randomization prioritizes abdominal adiposity as an independent causal factor for liver fat accumulation and cardiometabolic diseases

Background

Observational studies have linked adiposity and especially abdominal adiposity to liver fat accumulation and non-alcoholic fatty liver disease. These traits are also associated with type 2 diabetes and coronary artery disease but the causal factor(s) underlying these associations remain unexplored.

Methods

We used a multivariable Mendelian randomization study design to determine whether body mass index and waist circumference were causally associated with non-alcoholic fatty liver disease using publicly available genome-wide association study summary statistics of the UK Biobank (n = 461,460) and of non-alcoholic fatty liver disease (8434 cases and 770,180 control). A multivariable Mendelian randomization study design was also used to determine the respective causal contributions of waist circumference and liver fat (n = 32,858) to type 2 diabetes and coronary artery disease.

Results

Using multivariable Mendelian randomization we show that waist circumference increase non-alcoholic fatty liver disease risk even when accounting for body mass index (odd ratio per 1-standard deviation increase = 2.35 95% CI = 1.31-4.22, p = 4.2e-03), but body mass index does not increase non-alcoholic fatty liver disease risk when accounting for waist circumference (0.86 95% CI = 0.54-1.38, p = 5.4e-01). In multivariable Mendelian randomization analyses accounting for liver fat, waist circumference remains strongly associated with both type 2 diabetes (3.27 95% CI = 2.89-3.69, p = 3.8e-80) and coronary artery disease (1.66 95% CI = 1.54-1.8, p = 3.4e-37).

Conclusions

These results identify waist circumference as a strong, independent, and causal contributor to non-alcoholic fatty liver disease, type 2 diabetes and coronary artery disease, thereby highlighting the importance of assessing body fat distribution for the prediction and prevention of cardiometabolic diseases.

The Association between Anthropometry Indices and Serum Concentrations of Gamma-Glutamyl Transferase, Alkaline Phosphatase, Alanine Aminotransferase, and Aspartate Aminotransferase

Background

Nowadays, metabolic syndrome (MetS) has become a great public health crisis that threatens too many lives worldwide. Many previous studies have been investigated the association between MetS and anthropometric indices. This study is aimed at investigating the association between anthropometric indices with gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). We were using data from a large population-based cohort of seemingly healthy women and men.

Methods

A total of 7216 participants were included in this study. The serum levels of GGT, ALP, ALT, and AST with bioimpedance measures were obtained at the time of enrollment. Multiple regression analysis was performed to assess the relationship between anthropometric indices and serum levels of the aforementioned laboratory tests.

Results

Serum levels of GGT, ALP, ALT, and AST significantly correlated with body mass index (BMI). Only ALP had a significant association with visceral fat area (VFA). AST, ALT, and ALP levels had a positive correlation with 50 kHz whole-body phase.

Conclusion

From the findings of this study, body mass index consistently appeared a good predictor of elevated hepatic enzymes and triglycerides. Thus, it can be helpful in clinical settings to identify patients at risk of nonalcoholic fatty liver disease, which is closely related to metabolic syndrome.

The intestinal 3M (microbiota, metabolism, metabolome) zeitgeist - from fundamentals to future challenges

The role of the intestine in human health and disease has historically been neglected and was mostly attributed to digestive and absorptive functions. In the past two decades, however, discoveries related to human nutrition and intestinal host-microbe reciprocal interaction have established the essential role of intestinal health in the pathogenesis of chronic diseases and the overall wellbeing. That transfer of gut microbiota could be a means of disease phenotype transfer has revolutionized our understanding of chronic disease pathogenesis. This narrative review highlights the major concepts related to intestinal microbiota, metabolism, and metabolome (3M) that have facilitated our fundamental understanding of the association between the intestine, and human health and disease. In line with increased interest of microbiota-dependent modulation of human health by dietary phytochemicals, we have also discussed the emerging concepts beyond the phytochemical bioactivities which emphasizes the integral role of microbial metabolites of parent phytochemicals at extraintestinal tissues. Finally, this review concludes with challenges and future prospects in defining the 3M interactions and has emphasized the fact that, it takes 'guts' to stay healthy.

Are sex disparities in COVID-19 a predictable outcome of failing men's health provision?

The COVID-19 pandemic, caused by the SARS-CoV-2 coronavirus, has taken a catastrophic toll on society, health-care systems and the economy. Notably, COVID-19 has been shown to be associated with a higher mortality rate in men than in women. This disparity is likely to be a consequence of a failure to invest in men’s health, as it has also been established that men have a lower life expectancy and poorer outcomes from non-communicable diseases than women. A variety of biological, social and economic factors have contributed to the sex disparities in mortality from COVID-19. A streamlined men’s health programme — with the urologist as the gatekeeper of men’s health — is needed to help prevent future tragedies of this nature.

COVID-19 has been shown to be associated with a higher mortality rate in men than in women. In this Perspectives article, the authors posit that this disparity is due to a failure to invest in men’s health and discuss the biological, social and economic factors that have contributed to the sex disparities in mortality from COVID-19, as well as considering how a streamlined men’s health programme with the urologist in a central role could address these issues.

Adipose Tissue Fibrosis in Obesity: Etiology and Challenges

Obesity is a chronic and progressive process affecting whole-body energy balance and is associated with comorbidities development. In addition to increased fat mass, obesity induces white adipose tissue (WAT) inflammation and fibrosis, leading to local and systemic metabolic dysfunctions, such as insulin resistance (IR). Accordingly, limiting inflammation or fibrosis deposition may improve IR and glucose homeostasis. Although no targeted therapy yet exists to slow or reverse adipose tissue fibrosis, a number of findings have clarified the underlying cellular and molecular mechanisms. In this review, we highlight adipose tissue remodeling events shown to be associated with fibrosis deposition, with a focus on adipose progenitors involved in obesity-induced healthy as well as unhealthy WAT expansion. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Depleting hypothalamic somatostatinergic neurons recapitulates diabetic phenotypes in mouse brain, bone marrow, adipose and retina

AIMS/HYPOTHESIS

Hypothalamic inflammation and sympathetic nervous system hyperactivity are hallmark features of the metabolic syndrome and type 2 diabetes. Hypothalamic inflammation may aggravate metabolic and immunological pathologies due to extensive sympathetic activation of peripheral tissues. Loss of somatostatinergic (SST) neurons may contribute to enhanced hypothalamic inflammation.

METHODS

The present data show that leptin receptor-deficient (db/db) mice exhibit reduced hypothalamic SST neurons, particularly in the periventricular nucleus. We model this finding, using adeno-associated virus delivery of diphtheria toxin subunit A (DTA) driven by an SST-cre system to deplete these neurons in Sst^cre/gfp mice (SST-DTA).

RESULTS

SST-DTA mice exhibit enhanced hypothalamic c-Fos expression and brain inflammation as demonstrated by microglial and astrocytic activation. Bone marrow from SST-DTA mice undergoes skewed haematopoiesis, generating excess granulocyte-monocyte progenitors and increased proinflammatory (C-C chemokine receptor type 2; CCR2^hi) monocytes. SST-DTA mice exhibited a 'diabetic retinopathy-like' phenotype: reduced visual function by optokinetic response (0.4 vs 0.25 cycles/degree; SST-DTA vs control mice); delayed electroretinogram oscillatory potentials; and increased percentages of retinal monocytes. Finally, mesenteric visceral adipose tissue from SST-DTA mice was resistant to catecholamine-induced lipolysis, displaying 50% reduction in isoprenaline (isoproterenol)-induced lipolysis compared with control littermates. Importantly, hyperglycaemia was not observed in SST-DTA mice.

CONCLUSIONS/INTERPRETATION

The isolated reduction in hypothalamic SST neurons was able to recapitulate several hallmark features of type 2 diabetes in disease-relevant tissues.

Prenatal alcohol-induced sex differences in immune, metabolic and neurobehavioral outcomes in adult rats

Prenatal alcohol exposure (PAE) can result in neurobehavioral anomalies, that may be exacerbated by co-occurring metabolic and immune system deficits. To test the hypothesis that the peripheral inflammation in adult PAE offspring is linked to poor glucose metabolism and neurocognitive deficits, pregnant Sprague-Dawley rats were exposed to ethanol vapor or ambient air during the latter half of gestation. We assessed, in adult offspring of both sexes, performance on a battery of neurocognitive behaviors, glucose tolerance, circulating and splenic immune cells by flow-cytometry, and circulating and tissue (liver, mesenteric adipose, and spleen) cytokines by multiplexed assays. PAE reduced both the ratio of spleen to body weight and splenic regulatory T-cell (Treg) numbers. PAE males, but not females exhibited an increase in circulating monocytes. Overall, PAE males exhibited a suppression of cytokine levels, while PAE females exhibited elevated cytokines in mesenteric adipose tissue (IL-6 and IL1α) and liver (IFN-γ, IL-1β, IL-13, IL-18, IL-12p70, and MCP-1), along with increased glucose intolerance. Behavioral analysis also showed sex-dependent PAE effects. PAE-males exhibited increased anxiety-like behavior while PAE-females showed decreased social interaction. PAE offspring of both sexes exhibited impaired recognition of novel objects. Multilinear regression modeling to predict the association between peripheral immune status, glucose intolerance and behavioral outcomes, showed that in PAE offspring, higher levels of adipose leptin and liver TNF- α predicted higher circulating glucose levels. Lower liver IL-1 α and higher plasma fractalkine predicted more time spent in the center of an open-field with sex being an additional predictor. Higher circulating and splenic Tregs predicted better social interaction in the PAE-offspring. Collectively, our data show that peripheral immune status is a persistent, sex-dependent predictor of glucose intolerance and neurobehavioral function in adult PAE offspring.

Fasting, non-fasting and postprandial triglycerides for screening cardiometabolic risk

Fasting triacylglycerols have long been associated with cardiovascular disease (CVD) and other cardiometabolic conditions. Evidence suggests that non-fasting triglycerides (i.e. measured within 8 h of eating) better predict CVD than fasting triglycerides, which has led several organisations to recommend non-fasting lipid panels as the new clinical standard. However, unstandardised assessment protocols associated with non-fasting triglyceride measurement may lead to misclassification, with at-risk individuals being overlooked. A third type of triglyceride assessment, postprandial testing, is more controlled, yet historically has been difficult to implement due to the time and effort required to execute it. Here, we review differences in assessment, the underlying physiology and the pathophysiological relevance of elevated fasting, non-fasting and postprandial triglycerides. We also present data suggesting that there may be a distinct advantage of postprandial triglycerides, even over non-fasting triglycerides, for early detection of CVD risk and offer suggestions to make postprandial protocols more clinically feasible.

Pleiotrophin Deficiency Induces Browning of Periovarian Adipose Tissue and Protects against High-Fat Diet-Induced Hepatic Steatosis

(1) Background: Pleiotrophin preserves insulin sensitivity, regulates adipose tissue lipid turnover and plasticity, energy metabolism and thermogenesis. The aim of this study was to determine the role of pleiotrophin in hepatic lipid metabolism and in the metabolic crosstalk between the liver and brown and white adipose tissue (AT) in a high-fat diet-induced (HFD) obesity mice model. (2) Methods: We analyzed circulating variables, lipid metabolism (hepatic lipid content and mRNA expression), brown AT thermogenesis (UCP-1 expression) and periovarian AT browning (brown adipocyte markers mRNA and immunodetection) in Ptn-/- mice either fed with standard-chow diet or with HFD and in their corresponding Ptn+/+ counterparts. (3) Results: HFD-Ptn-/- mice are protected against the development of HFD-induced insulin resistance, had lower liver lipid content and lower expression of the key enzymes involved in triacylglycerides and fatty acid synthesis in liver. HFD-Ptn-/- mice showed higher UCP-1 expression in brown AT. Moreover, Ptn deletion increased the expression of specific markers of brown/beige adipocytes and was associated with the immunodetection of UCP-1 enriched multilocular adipocytes in periovarian AT. (4) Conclusions: Ptn deletion protects against the development of HFD-induced insulin resistance and liver steatosis, by increasing UCP-1 expression in brown AT and promoting periovarian AT browning.

Distribution of HOMA-IR in a population-based cohort and proposal for reference intervals

OBJECTIVES

Insulin resistance (IR) is a hallmark of type 2 diabetes mellitus (DM). The homeostatic model assessment of insulin resistance (HOMA-IR) provides an estimate for IR from fasting glucose and insulin serum concentrations. The aim of this study was to obtain a reference interval for HOMA-IR for a specific insulin immunoassay.

METHODS

The Gutenberg Health Study (GHS) is a population-based, prospective, single-center cohort study in Germany with 15,030 participants aged 35-74 years. Fasting glucose, insulin, and C-peptide were available in 10,340 participants. HOMA-IR was calculated in this group and three reference subgroups with increasingly more stringent inclusion criteria. Age- and sex-dependent distributions of HOMA-IR and reference intervals were obtained. In a substudy three insulin assays were compared and HOMA-IR estimated for each assay.

RESULTS

Among the 10,340 participants analyzed there were 6,590 non-diabetic, 2,901 prediabetic, and 849 diabetic individuals. Median (interquartile range [IQR]) HOMA-IR was 1.54 (1.13/2.19), 2.00 (1.39/2.99), and 4.00 (2.52/6.51), respectively. The most stringently selected reference group consisted of 1,065 persons. Median (IQR) HOMA-IR was 1.09 (0.85/1.42) with no significant difference between men and women. The 97.5th percentile was 2.35. There was a non-significant trend towards higher values with older age. Comparison of three immunoassays for insulin showed an unsatisfactory correlation among the assays and systematic differences in calculated HOMA-IR.

CONCLUSIONS

We present HOMA-IR reference intervals for adults derived by more or less stringent selection criteria for the reference cohort. In addition we show that assay specific reference intervals for HOMA-IR are required.

Changes in abdominal subcutaneous adipose tissue phenotype following menopause is associated with increased visceral fat mass

Menopause is associated with a redistribution of adipose tissue towards central adiposity, known to cause insulin resistance. In this cross-sectional study of 33 women between 45 and 60 years, we assessed adipose tissue inflammation and morphology in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) across menopause and related this to menopausal differences in adipose tissue distribution and insulin resistance. We collected paired SAT and VAT biopsies from all women and combined this with anthropometric measurements and estimated whole-body insulin sensitivity. We found that menopause was associated with changes in adipose tissue phenotype related to metabolic dysfunction. In SAT, postmenopausal women showed adipocyte hypertrophy, increased inflammation, hypoxia and fibrosis. The postmenopausal changes in SAT was associated with increased visceral fat accumulation. In VAT, menopause was associated with adipocyte hypertrophy, immune cell infiltration and fibrosis. The postmenopausal changes in VAT phenotype was associated with decreased insulin sensitivity. Based on these findings we suggest, that menopause is associated with changes in adipose tissue phenotype related to metabolic dysfunction in both SAT and VAT. Whereas increased SAT inflammation in the context of menopause is associated with VAT accumulation, VAT morphology is related to insulin resistance.

Supplementation of cumin seed powder prevents oxidative stress, hyperlipidemia and non-alcoholic fatty liver in high fat diet fed rats

The present investigation was an attempt to evaluate the hypoglycemic, lipid-lowering, antioxidant and hepatoprotective effects of cumin (Cuminum cyminum family: Apiaceae) supplementation in high fat (HF) diet fed rats. Male Wistar rats were divided into four groups, such as control, control+ cumin, HF and HF+ cumin. Oral glucose tolerance test, plasma lipids, oxidative stress parameters, antioxidant enzymes activities, and liver dysfunction marker enzyme activities were evaluated. Additionally, histological staining of liver tissue was performed to evaluate the inflammatory cells infiltration, iron deposition and fibrosis. The current investigation demonstrated that 1% (w/w) supplementation of cumin powder significantly reduced HF diet-induced glucose intolerance, epididymal and mesenteric fat wet weights and lipid parameters like triglycerides, total cholesterol and low-density lipoproteins. Oxidative stress-related biomarkers including thiobarbituric acid reactive substances (TBARS), nitric oxide (NO) and advanced oxidation protein product (APOP) were also reduced by cumin supplementation. Moreover, HF-diet increased the activity of hepatic biomarker enzymes such as alanine transaminase (ALT) and alkaline phosphatase (ALP) activities which were significantly reduced by cumin powder supplementation. On the other hand, cumin powder supplementation was able to restore the reduced glutathione level with parallel augmentation of the antioxidant enzymes activities such as superoxide dismutase (SOD) and catalase in liver of HF diet-fed rats. Additionally, histological assessments confirmed that cumin powder supplementation also normalized the fat droplet deposition and inflammatory cells infiltration in the liver of HF diet-fed rats. This study suggests that cumin powder supplementation ameliorates dyslipidemia, oxidative stress and hepatic damage in HF diet-fed rats.

Visceral obesity and insulin resistance associate with CD36 deletion in lymphatic endothelial cells

Disruption of lymphatic lipid transport is linked to obesity and type 2 diabetes (T2D), but regulation of lymphatic vessel function and its link to disease remain unclear. Here we show that intestinal lymphatic endothelial cells (LECs) have an increasing CD36 expression from lymphatic capillaries (lacteals) to collecting vessels, and that LEC CD36 regulates lymphatic integrity and optimizes lipid transport. Inducible deletion of CD36 in LECs in adult mice (Cd36^ΔLEC) increases discontinuity of LEC VE-cadherin junctions in lacteals and collecting vessels. Cd36^ΔLEC mice display slower transport of absorbed lipid, more permeable mesenteric lymphatics, accumulation of inflamed visceral fat and impaired glucose disposal. CD36 silencing in cultured LECs suppresses cell respiration, reduces VEGF-C-mediated VEGFR2/AKT phosphorylation and destabilizes VE-cadherin junctions. Thus, LEC CD36 optimizes lymphatic junctions and integrity of lymphatic lipid transport, and its loss in mice causes lymph leakage, visceral adiposity and glucose intolerance, phenotypes that increase risk of T2D.

Genetic variants in CD36 have been associated with metabolic syndrome. Here, the authors found that lymphatic vessel integrity and lipid transport are influenced by CD36 expression, and lymphatic endothelial cell CD36 deficiency causes visceral obesity and insulin resistance, which are risk factors for metabolic syndrome and diabetes.

Male and Female Animals Respond Differently to High-Fat Diet and Regular Exercise Training in a Mouse Model of Hyperlipidemia

Inappropriate nutrition and a sedentary lifestyle can lead to obesity, one of the most common risk factors for several chronic diseases. Although regular physical exercise is an efficient approach to improve cardiometabolic health, the exact cellular processes are still not fully understood. We aimed to analyze the morphological, gene expression, and lipidomic patterns in the liver and adipose tissues in response to regular exercise. Healthy (wild type on a normal diet) and hyperlipidemic, high-fat diet-fed (HFD-fed) apolipoprotein B-100 (APOB-100)-overexpressing mice were trained by treadmill running for 7 months. The serum concentrations of triglyceride and tumor necrosis factor α (TNFα), as well as the level of lipid accumulation in the liver, were significantly higher in HFD-fed APOB-100 males compared to females. However, regular exercise almost completely abolished lipid accumulation in the liver of hyperlipidemic animals. The expression level of the thermogenesis marker, uncoupling protein-1 (Ucp1), was significantly higher in the subcutaneous white adipose tissue of healthy females, as well as in the brown adipose tissue of HFD-fed APOB-100 females, compared to males. Lipidomic analyses revealed that hyperlipidemia essentially remodeled the lipidome of brown adipose tissue, affecting both the membrane and storage lipid fractions, which was partially restored by exercise in both sexes. Our results revealed more severe metabolic disturbances in HFD-fed APOB-100 males compared to females. However, exercise efficiently reduced the body weight, serum triglyceride levels, expression of pro-inflammatory factors, and hepatic lipid accumulation in our model.

Removal of Epididymal Visceral Adipose Tissue Prevents Obesity-Induced Multi-organ Insulin Resistance in Male Mice

Obesity is associated with insulin resistance, an important risk factor of type 2 diabetes, atherogenic dyslipidemia, and nonalcoholic fatty liver disease. The major purpose of this study was to test hypothesize that prophylactic removal of epididymal visceral adipose tissue (VAT) prevents obesity-induced multi-organ (liver, skeletal muscle, adipose tissue) insulin resistance. Accordingly, we surgically removed epididymal VAT pads from adult C57BL/6J mice and evaluated in vivo and cellular metabolic pathways involved in glucose and lipid metabolism following chronic high-fat diet (HFD) feeding. We found that VAT removal decreases HFD-induced body weight gain while increasing subcutaneous adipose tissue (SAT) mass. Strikingly, VAT removal prevents obesity-induced insulin resistance and hyperinsulinemia and markedly enhances insulin-stimulated AKT-phosphorylation at serine-473 (Ser473) and threonine-308 (Thr308) sites in SAT, liver, and skeletal muscle. VAT removal leads to decreases in plasma lipid concentrations and hepatic triglyceride (TG) content. In addition, VAT removal increases circulating adiponectin, a key insulin-sensitizing adipokine, whereas it decreases circulating interleukin 6, a pro-inflammatory adipokine. Consistent with these findings, VAT removal increases adenosine monophosphate-activated protein kinase C phosphorylation, a major downstream target of adiponectin signaling. Data obtained from RNA sequencing suggest that VAT removal prevents obesity-induced oxidative stress and inflammation in liver and SAT, respectively. Taken together, these findings highlight the metabolic benefits and possible action mechanisms of prophylactic VAT removal on obesity-induced insulin resistance and hepatosteatosis. Our results also provide important insight into understanding the extraordinary capability of adipose tissue to influence whole-body glucose and lipid metabolism as an active endocrine organ.

Factors Affecting Metabolic Outcomes Post Bariatric Surgery: Role of Adipose Tissue

Obesity is an ever-growing public health crisis, and bariatric surgery (BS) has become a valuable tool in ameliorating obesity, along with comorbid conditions such as diabetes, dyslipidemia and hypertension. BS techniques have come a long way, leading to impressive improvements in the health of the majority of patients. Unfortunately, not every patient responds optimally to BS and there is no method that is sufficient to pre-operatively predict who will receive maximum benefit from this surgical intervention. This review focuses on the adipose tissue characteristics and related parameters that may affect outcomes, as well as the potential influences of insulin resistance, BMI, age, psychologic and genetic factors. Understanding the role of these factors may help predict who will benefit the most from BS.

Etoricoxib treatment prevented body weight gain and ameliorated oxidative stress in the liver of high-fat diet-fed rats

The main focus of this study was to determine the role of etoricoxib in counterbalancing the oxidative stress, metabolic disturbances, and inflammation in high-fat (HF) diet-induced obese rats. To conduct this study, 28 male Wistar rats (weighing 190-210 g) were distributed randomly into four groups: control, control + etoricoxib, HF, and HF + etoricoxib. After 8 weeks of treatment with etoricoxib (200 mg/kg), all the animals were sacrificed followed by the collection of blood and tissue samples in order to perform biochemical tests along with histological staining on hepatic tissues. According to this study, etoricoxib treatment prevented the body weight gain in HF diet-fed rats. Furthermore, rats of HF + etoricoxib group exhibited better blood glucose tolerance than the rats of HF diet-fed group. In addition, etoricoxib also markedly normalized HF diet-mediated rise of hepatic enzyme activity. Etoricoxib treatment lowered the level of oxidative stress indicators significantly with a parallel augmentation of antioxidant enzyme activities. Furthermore, etoricoxib administration helped in preventing inflammatory cell invasion, collagen accumulation, and fibrotic catastrophe in HF diet-fed rats. The findings of the present work are suggestive of the helpful role of etoricoxib in deterring the metabolic syndrome as well as other deleterious pathological changes afflicting the HF diet-fed rats.

Adipose tissue inflammation and metabolic dysfunction in obesity

Several lines of preclinical and clinical research have confirmed that chronic low-grade inflammation of adipose tissue is mechanistically linked to metabolic disease and organ tissue complications in the overweight and obese organism. Despite this widely confirmed paradigm, numerous open questions and knowledge gaps remain to be investigated. This is mainly due to the intricately intertwined cross-talk of various pro- and anti-inflammatory signaling cascades involved in the immune response of expanding adipose depots, particularly the visceral adipose tissue. Adipose tissue inflammation is initiated and sustained over time by dysfunctional adipocytes that secrete inflammatory adipokines and by infiltration of bone marrow-derived immune cells that signal via production of cytokines and chemokines. Despite its low-grade nature, adipose tissue inflammation negatively impacts remote organ function, a phenomenon that is considered causative of the complications of obesity. The aim of this review is to broadly present an overview of adipose tissue inflammation by highlighting the most recent reports in the scientific literature and summarizing our overall understanding of the field. We also discuss key endogenous anti-inflammatory mediators and analyze their mechanistic role(s) in the pathogenesis and treatment of adipose tissue inflammation. In doing so, we hope to stimulate studies to uncover novel physiological, cellular, and molecular targets for the treatment of obesity.

Adipose tissue in health and disease

Adipose, or fat, tissue (AT) was once considered an inert tissue that primarily existed to store lipids, and was not historically recognized as an important organ in the regulation and maintenance of health. With the rise of obesity and more rigorous research, AT is now recognized as a highly complex metabolic organ involved in a host of important physiological functions, including glucose homeostasis and a multitude of endocrine capabilities. AT dysfunction has been implicated in several disease states, most notably obesity, metabolic syndrome and type 2 diabetes. The study of AT has provided useful insight in developing strategies to combat these highly prevalent metabolic diseases. This review highlights the major functions of adipose tissue and the consequences that can occur when disruption of these functions leads to systemic metabolic dysfunction.

GRK2 levels in myeloid cells modulate adipose-liver crosstalk in high fat diet-induced obesity

Macrophages are key effector cells in obesity-associated inflammation. G protein-coupled receptor kinase 2 (GRK2) is highly expressed in different immune cell types. Using LysM-GRK2+/- mice, we uncover that a reduction of GRK2 levels in myeloid cells prevents the development of glucose intolerance and hyperglycemia after a high fat diet (HFD) through modulation of the macrophage pro-inflammatory profile. Low levels of myeloid GRK2 confer protection against hepatic insulin resistance, steatosis and inflammation. In adipose tissue, pro-inflammatory cytokines are reduced and insulin signaling is preserved. Macrophages from LysM-GRK2+/- mice secrete less pro-inflammatory cytokines when stimulated with lipopolysaccharide (LPS) and their conditioned media has a reduced pathological influence in cultured adipocytes or naïve bone marrow-derived macrophages. Our data indicate that reducing GRK2 levels in myeloid cells, by attenuating pro-inflammatory features of macrophages, has a relevant impact in adipose-liver crosstalk, thus preventing high fat diet-induced metabolic alterations.

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.