Differential responses of visceral and subcutaneous fat depots to nutrients

Transition of visceral adiposity index and risk of cardiovascular disease in middle-aged and older Chinese adults

OBJECTIVE

Visceral obesity and the lifetime risk of cardiovascular disease (CVD) have received increasing attention. However, the relationship between dynamic changes in visceral obesity and CVD has not been studied. We aimed to determine the association of visceral adiposity index (VAI) transition with CVD risk.

METHODS

A total of 5395 participants were recruited in 2011-2012 and followed up until 2018 from the China Health and Retirement Longitudinal Study. The cut-off value of the VAI was obtained by the receiver-operating characteristic curve. Participants were grouped based on VAI change patterns during the follow-up period (2011-2015): the low-low group, low-high group, high-low group, and high-high group. CVD was defined as a medical diagnosis of heart disease and/or stroke. A Cox proportional hazards model was used to evaluate the correlation between VAI transition and CVD.

RESULTS

Over a median follow-up period of 7 years, 969 participants (17.9 %) developed CVD. VAI change patterns were significantly associated with CVD risk after adjustment for demographic characteristics and risk factors. The high-high group (hazard ratio (HR): 1.65, 95 % confidence interval (CI): 1.39-1.97) and the low-high group (HR: 1.29, 95 % CI: 1.04-1.61) were associated with a higher risk of CVD after adjusting for demographic characteristics and traditional risk factors compared to the low-low group, while the effect in the high-low group was not significant.

CONCLUSIONS

VAI transition was significantly associated with the risk of CVD. Monitoring the dynamics of the VAI in public health practice would help prevent CVD.

Metabolic remodeling of visceral and subcutaneous white adipose tissue during reacclimation of rats after cold

Deciphering lipid metabolism in white adipose tissue (WAT) depots during weight gain is important to understand the heterogeneity of WAT and its roles in obesity. Here, we examined the expression of key enzymes of lipid metabolism and changes in the morphology of representative visceral (epididymal) and subcutaneous (inguinal) WAT (eWAT and iWAT, respectively)-in adult male rats acclimated to cold (4 ± 1 °C) for 45 days and reacclimated to room temperature (RT, 22 ± 1 °C) for 1, 3, 7, 12, 21, or 45 days. The relative mass of both depots decreased to a similar extent after cold acclimation. However, fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH), and medium-chain acyl-CoA dehydrogenase (ACADM) protein level increased only in eWAT, whereas adipose triglyceride lipase (ATGL) expression increased only in iWAT. During reacclimation, the relative mass of eWAT reached control values on day 12 and that of iWAT on day 45 of reacclimation. The faster recovery of eWAT mass is associated with higher expression of FAS, acetyl-CoA carboxylase (ACC), G6PDH, and ACADM during reacclimation and a delayed increase in ATGL. The absence of an increase in proliferating cell nuclear antigen suggests that the observed depot-specific mass increase is predominantly due to metabolic adjustments. In summary, this study shows a differential rate of visceral and subcutaneous adipose tissue weight regain during post-cold reacclimation of rats at RT. Faster recovery of the visceral WAT as compared to subcutaneous WAT during reacclimation at RT could be attributed to observed differences in the expression patterns of lipid metabolic enzymes.

Postbiotic potential of Bacillus velezensis KMU01 cell-free supernatant for the alleviation of obesity in mice

Attention toward the preventive effects of postbiotics on metabolic diseases has increased because of greater stability and safety over probiotics. However, studies regarding the bioactive effects of postbiotics, especially from probiotic Bacillus strains, are relatively limited. The anti-obesity effects of the cell-free culture supernatant of Bacillus velezensis KMU01 (CFS-B.vele) were evaluated using high-fat-diet (HFD)-induced mice. HFD-induced mice (n = 8 per group) received equal volumes of (1) CFS-B.vele (114 mg/kg) in PBS, (2) Xenical in PBS, or (3) PBS alone by oral gavage daily for 13 weeks. The results demonstrated that CFS-B.vele changed the gut microbiota and showed anti-obesity effects in HFD-induced obese mice. The elevated Firmicutes/Bacteroidota ratio induced by HFD was decreased in the CFS-B.vele group compared to the other groups (p < 0.05). The CFS-B.vele intervention led to the enrichment of SCFA-producers, such as Roseburia and Eubacterium, in the cecum, suggesting their potential involvement in the amelioration of obesity. Due to these changes, the various obesity-related biomarkers (body weight, fat in tissue, white adipose tissue weight and size, serum LDL-cholesterol level, hepatic lipid accumulation, and adipogenesis/lipogenesis-related gene/protein expression) were improved. Our findings suggest that CFS-B.vele has potential as a novel anti-obesity agent through modulation of the gut microbiota.

Prevalence and related factors of abdominal obesity among urban adults aged 35 to 79 years in southwest China

Objectives

This study aimed to investigate the prevalence and related factors of abdominal obesity among urban adults aged 35 to 79 years in southwest China.

Methods

From September 2013 to March 2014, a multi-stage sampling was conducted, and a total of 10,981 people aged 35-79 years living in Chengdu and Chongqing were included. More than 30 investigators were trained in data collection, including questionnaire, anthropometric measurements and blood biomarkers testing. Abdominal obesity was defined as waist circumference ≥ 90 cm for men and ≥ 85 cm for women.

Results

The prevalence of abdominal obesity was 30.7%, 24.8% in males and 33.9% in females (p < 0.001). The prevalence of abdominal obesity increased with BMI. The prevalence of abdominal obesity was positively correlated with age, sex, marriage, alcohol consumption, hypertension and diabetes, and negatively correlated with high education level, smoking and Physical activity.

Conclusion

The prevalence of abdominal obesity among adults aged 35-79 in urban communities in southwest China is high, which is close to that of adults in urban communities in China. We should strengthen health education among the population, adopt healthy diet, maintain moderate physical activity and other measures to curb the prevalence of abdominal obesity in urban communities in southwest China.

Sex differences in body composition in people with prediabetes and type 2 diabetes as compared with people with normal glucose metabolism: the Maastricht Study

AIMS/HYPOTHESIS

Obesity is a major risk factor for type 2 diabetes. However, body composition differs between women and men. In this study we investigate the association between diabetes status and body composition and whether this association is moderated by sex.

METHODS

In a population-based cohort study (n=7639; age 40-75 years, 50% women, 25% type 2 diabetes), we estimated the sex-specific associations, and differences therein, of prediabetes (i.e. impaired fasting glucose and/or impaired glucose tolerance) and type 2 diabetes (reference: normal glucose metabolism [NGM]) with dual-energy x-ray absorptiometry (DEXA)- and MRI-derived measures of body composition and with hip circumference. Sex differences were analysed using adjusted regression models with interaction terms of sex-by-diabetes status.

RESULTS

Compared with their NGM counterparts, both women and men with prediabetes and type 2 diabetes had more fat and lean mass and a greater hip circumference. The differences in subcutaneous adipose tissue, hip circumference and total and peripheral lean mass between type 2 diabetes and NGM were greater in women than men (women minus men [W-M] mean difference [95% CI]: 15.0 cm2 [1.5, 28.5], 3.2 cm [2.2, 4.1], 690 g [8, 1372] and 443 g [142, 744], respectively). The difference in visceral adipose tissue between type 2 diabetes and NGM was greater in men than women (W-M mean difference [95% CI]: -14.8 cm2 [-26.4, -3.1]). There was no sex difference in the percentage of liver fat between type 2 diabetes and NGM. The differences in measures of body composition between prediabetes and NGM were generally in the same direction, but were not significantly different between women and men.

CONCLUSIONS/INTERPRETATION

This study indicates that there are sex differences in body composition associated with type 2 diabetes. The pathophysiological significance of these sex-associated differences requires further study.

A nexus of lipid and O-Glcnac metabolism in physiology and disease

Although traditionally considered a glucose metabolism-associated modification, the O-linked β-N-Acetylglucosamine (O-GlcNAc) regulatory system interacts extensively with lipids and is required to maintain lipid homeostasis. The enzymes of O-GlcNAc cycling have molecular properties consistent with those expected of broad-spectrum environmental sensors. By direct protein-protein interactions and catalytic modification, O-GlcNAc cycling enzymes may provide both acute and long-term adaptation to stress and other environmental stimuli such as nutrient availability. Depending on the cell type, hyperlipidemia potentiates or depresses O-GlcNAc levels, sometimes biphasically, through a diversity of unique mechanisms that target UDP-GlcNAc synthesis and the availability, activity and substrate selectivity of the glycosylation enzymes, O-GlcNAc Transferase (OGT) and O-GlcNAcase (OGA). At the same time, OGT activity in multiple tissues has been implicated in the homeostatic regulation of systemic lipid uptake, storage and release. Hyperlipidemic patterns of O-GlcNAcylation in these cells are consistent with both transient physiological adaptation and feedback uninhibited obesogenic and metabolic dysregulation. In this review, we summarize the numerous interconnections between lipid and O-GlcNAc metabolism. These links provide insights into how the O-GlcNAc regulatory system may contribute to lipid-associated diseases including obesity and metabolic syndrome.

Obesity, Senescence, and Senolytics

Obesity is a major risk factor for the development of comorbidities such as type 2 diabetes, neurodegenerative disorders, osteoarthritis, cancer, cardiovascular and renal diseases. The onset of obesity is linked to an increase of senescent cells within adipose tissue and other organs. Cellular senescence is a stress response that has been shown to be causally linked to aging and development of various age-related diseases such as obesity. The senescence-associated-secretory phenotype of senescent cells creates a chronic inflammatory milieu that leads to local and systemic dysfunction. The elimination of senescent cells using pharmacological approaches (i.e., senolytics) has been shown to delay, prevent, or alleviate obesity-related organ dysfunction.

Interleukin-1 in obesity-related low-grade inflammation: From molecular mechanisms to therapeutic strategies

Since adipose tissue (AT) can upregulate pro-inflammatory interleukins (ILs) via storing extra lipids in obesity, obesity is considered the leading cause of chronic low-grade inflammation. These ILs can pave the way for the infiltration of immune cells into the AT, ultimately resulting in low-grade inflammation and dysregulation of adipocytes. IL-1, which is divided into two subclasses, i.e., IL-1α and IL-1β, is a critical pro-inflammatory factor. In obesity, IL-1α and IL-1β can promote insulin resistance via impairing the function of adipocytes and promoting inflammation. The current study aims to review the detailed molecular mechanisms and the roles of IL-1α and IL-1β and their antagonist, interleukin-1 receptor antagonist(IL-1Ra), in developing obesity-related inflammatory complications, i.e., type II diabetes (T2D), non-alcoholic steatohepatitis (NASH), atherosclerosis, and cognitive disorders. Besides, the current study discusses the recent advances in natural drugs, synthetic agents, and gene therapy approaches to treat obesity-related inflammatory complications via suppressing IL-1.

Adipose Tissue Epigenetic Profile in Obesity-Related Dysglycemia - A Systematic Review

BACKGROUND

Obesity is a major risk factor for dysglycemic disorders, including type 2 diabetes (T2D). However, there is wide phenotypic variation in metabolic profiles. Tissue-specific epigenetic modifications could be partially accountable for the observed phenotypic variability.

SCOPE

The aim of this systematic review was to summarize the available data on epigenetic signatures in human adipose tissue (AT) that characterize overweight or obesity-related insulin resistance (IR) and dysglycemia states and to identify potential underlying mechanisms through the use of unbiased bioinformatics approaches.

METHODS

Original data published in the last decade concerning the comparison of epigenetic marks in human AT of individuals with metabolically unhealthy overweight/obesity (MUHO) versus normal weight individuals or individuals with metabolically healthy overweight/obesity (MHO) was assessed. Furthermore, association of these epigenetic marks with IR/dysglycemic traits, including T2D, was compiled.

RESULTS

We catalogued more than two thousand differentially methylated regions (DMRs; above the cut-off of 5%) in the AT of individuals with MUHO compared to individuals with MHO. These DNA methylation changes were less likely to occur around the promoter regions and were enriched at loci implicated in intracellular signaling (signal transduction mediated by small GTPases, ERK1/2 signaling and intracellular trafficking). We also identified a network of seven transcription factors that may play an important role in targeting DNA methylation changes to specific genes in the AT of subjects with MUHO, contributing to the pathogeny of obesity-related IR/T2D. Furthermore, we found differentially methylated CpG sites at 8 genes that were present in AT and whole blood, suggesting that DMRs in whole blood could be potentially used as accessible biomarkers of MUHO.

CONCLUSIONS

The overall evidence linking epigenetic alterations in key tissues such AT to metabolic complications in human obesity is still very limited, highlighting the need for further studies, particularly those focusing on epigenetic marks other than DNA methylation. Our initial analysis suggests that DNA methylation patterns can potentially discriminate between MUHO from MHO and provide new clues into why some people with obesity are less susceptible to dysglycemia. Identifying AT-specific epigenetic targets could also lead to novel approaches to modify the progression of individuals with obesity towards metabolic disease.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, identifier CRD42021227237.

Weight gain during early adulthood, trajectory of body shape and the risk of nonalcoholic fatty liver disease: A prospective cohort study among women

BACKGROUND & AIMS

Obesity is established as a major risk factor for the development of nonalcoholic fatty liver disease (NAFLD). However, the influence of dynamic changes in adiposity over the life course on NAFLD risk remains poorly understood.

METHODS

We collected data from 110,054 women enrolled in the Nurses' Health Study II cohort. Early adulthood weight was ascertained at age 18 years, and weight gain since early adulthood was defined prospectively every 2 years. We used a group-based modeling approach to identify five trajectories of body shape from age 5 years up to age 50 years. NAFLD was defined by physician-confirmed diagnoses of fatty liver, after excluding excess alcohol intake and viral hepatitis, using validated approaches.

RESULTS

We documented 3798 NAFLD cases over a total of 20 years of follow-up. Compared to women who maintained stable weight (±2 kg), women with ≥20 kg of adulthood weight gain had the multivariable aHR of 6.96 (95% CI, 5.27-9.18), and this remained significant after further adjusting for early adulthood BMI and updated BMI (both P trend <0.0001). Compared to women with a medium-stable body shape trajectory, the multivariable aHRs for NAFLD were, 2.84 (95% CI, 2.50-3.22) for lean-marked increase, 2.60 (95% CI, 2.27-2.98) for medium-moderate increase, and 3.39 (95% CI, 2.95-3.89) for medium-marked increase.

CONCLUSIONS

Both early adulthood weight gain and lifetime body shape trajectory were significantly and independently associated with excess risk of developing NAFLD in mid-life. Maintaining both lean and stable weight throughout life may offer the greatest benefit for the prevention of NAFLD.

A conditional mouse expressing an activating mutation in NRF2 displays hyperplasia of the upper gastrointestinal tract and decreased white adipose tissue

Activation of the nuclear factor (erythroid-derived 2)-like 2 (NFE2L2 or NRF2) transcription factor is a critical and evolutionarily conserved cellular response to oxidative stress, metabolic stress, and xenobiotic insult. Deficiency of NRF2 results in hypersensitivity to a variety of stressors, whereas its aberrant activation contributes to several cancer types, most commonly squamous cell carcinomas of the esophagus, oral cavity, bladder, and lung. Between 10% and 35% of patients with squamous cell carcinomas display hyperactive NRF2 signaling, harboring activating mutations and copy number amplifications of the NFE2L2 oncogene or inactivating mutations or deletions of KEAP1 or CUL3, the proteins of which co-complex to ubiquitylate and degrade NRF2 protein. To better understand the role of NRF2 in tumorigenesis and more broadly in development, we engineered the endogenous Nfe2l2 genomic locus to create a conditional mutant LSL-Nrf2^E79Q mouse model. The E79Q mutation, one of the most commonly observed NRF2-activating mutations in human squamous cancers, codes for a mutant protein that does not undergo KEAP1/CUL3-dependent degradation, resulting in its constitutive activity. Expression of NRF2 E79Q protein in keratin 14 (KRT14)-positive murine tissues resulted in hyperplasia of squamous cell tissues of the tongue, forestomach, and esophagus, a stunted body axis, decreased weight, and decreased visceral adipose depots. RNA-seq profiling and follow-up validation studies of cultured NRF2^E79Q murine esophageal epithelial cells revealed known and novel NRF2-regulated transcriptional programs, including genes associated with squamous cell carcinoma (e.g. Myc), lipid and cellular metabolism (Hk2, Ppard), and growth factors (Areg, Bmp6, Vegfa). These data suggest that in addition to decreasing adipogenesis, KRT14-restricted NRF2 activation drives hyperplasia of the esophagus, forestomach, and tongue, but not formation of squamous cell carcinoma. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Distinct infrastructure of lipid networks in visceral and subcutaneous adipose tissues in overweight humans

BACKGROUND

Adipose tissue plays important roles in health and disease. Given the unique association of visceral adipose tissue with obesity-related metabolic diseases, the distribution of lipids between the major fat depots located in subcutaneous and visceral regions may shed new light on adipose tissue-specific roles in systemic metabolic perturbations.

OBJECTIVE

We sought to characterize the lipid networks and unveil differences in the metabolic infrastructure of the 2 adipose tissues that may have functional and nutritional implications.

METHODS

Paired visceral and subcutaneous adipose tissue samples were obtained from 17 overweight patients undergoing elective abdominal surgery. Ultra-performance LC-MS was used to measure 18,640 adipose-derived features; 520 were putatively identified. A stem cell model for adipogenesis was used to study the functional implications of the differences found.

RESULTS

Our analyses resulted in detailed lipid metabolic maps of the 2 major adipose tissues. They point to a higher accumulation of phosphatidylcholines, triacylglycerols, and diacylglycerols, although lower ceramide concentrations, in subcutaneous tissue. The degree of unsaturation was lower in visceral adipose tissue (VAT) phospholipids, indicating lower unsaturated fatty acid incorporation into adipose tissue. The differential abundance of phosphatidylcholines we found can be attributed at least partially to higher expression of phosphatidylethanolamine methyl transferase (PEMT). PEMT-deficient embryonic stem cells showed a dramatic decrease in adipogenesis, and the resulting adipocytes exhibited lower accumulation of lipid droplets, in line with the lower concentrations of glycerolipids in VAT. Ceramides may inhibit the expression of PEMT by increased insulin resistance, thus potentially suggesting a functional pathway that integrates ceramide, PEMT, and glycerolipid biosynthetic pathways.

CONCLUSIONS

Our work unveils differential infrastructure of the lipid networks in visceral and subcutaneous adipose tissues and suggests an integrative pathway, with a discriminative flux between adipose tissues.

Increased Visceral Adipose Tissue Without Weight Retention at 59 Weeks Postpartum

OBJECTIVE

This study aimed to determine whether controlling maternal gestational weight gain (GWG) influences adipose tissue distribution at 1 year postpartum.

METHODS

Women with overweight or obesity (n = 210, BMI ≥ 25 or ≥ 30) were randomized to a lifestyle intervention (LI) designed to control GWG or to usual obstetrical care (UC). Measures included anthropometry, whole-body magnetic resonance imaging for visceral (VAT), intermuscular, and subcutaneous adipose tissue, and cardiometabolic risk factors in pregnancy (15 and 35 weeks) and after delivery (15 and 59 weeks).

RESULTS

Baseline (15 weeks) characteristics were similar (mean [SD]: age, 33.8 [4.3] years; weight, 81.9 [13.7] kg; BMI, 30.4 [4.5]; gestational age at randomization, 14.9 [0.8] weeks). LI had less GWG (1.79 kg; P = 0.003) and subcutaneous adipose tissue gain at 35 weeks gestation (P < 0.01). UC postpartum weight (2.92 kg) was higher at 15 weeks but not different from baseline or LI at 59 weeks postpartum. Postpartum VAT increased from baseline in LI by 0.23 kg at 15 weeks and 0.55 kg at 59 weeks; in UC, it increased by 0.34 kg at 15 and 59 weeks. Intermuscular adipose tissue remained elevated in LI (0.22 kg) at 59 weeks. VAT was associated with several cardiometabolic risk factors at 59 weeks.

CONCLUSIONS

Despite no weight retention at 59 weeks postpartum, women had increased VAT by ~30%. Postpartum modifiable behaviors are warranted to lower the risk of VAT retention.

Prevalence of Abdominal Obesity in China: Results from a Cross-Sectional Study of Nearly Half a Million Participants

OBJECTIVE

This study aimed to examine the latest prevalence of abdominal obesity in China based on nationally representative data.

METHODS

A stratified, multistage, random sampling method was used to obtain a nationally representative sample of residents aged ≥ 18 years from 31 provinces in mainland China from October 2012 to December 2015. Abdominal obesity was defined as a waist circumference ≥ 90 cm for men and a waist circumference ≥ 85 cm for women.

RESULTS

The data of 441,306 participants were analyzed. The prevalence of abdominal obesity was 29.1% (28.6% in men and 29.6% in women); the number of adults with abdominal obesity was estimated to be 277.8 million (approximately 140.1 million in men and 137.7 million in women). The prevalence of abdominal obesity varied considerably among provinces. In general, the prevalence of abdominal obesity was higher in the northern, lower in the southern, higher in the western, and lower in the eastern areas of China. Besides the regional disparities, the prevalence of abdominal obesity varied greatly among different population subgroups.

CONCLUSIONS

Abdominal obesity is highly prevalent among Chinese adults. National and provincial obesity control and prevention strategies should be public health priorities in China. To better control obesity, the underlying reasons for the regional disparities need to be addressed.

An update on metabolic syndrome: Metabolic risk markers and adipokines in the development of metabolic syndrome

Metabolic syndrome is a collection of physiological and biochemical abnormalities about 20-25% of adult population in developing countries is suffering from metabolic syndrome. Previous research demonstrated that adipose tissue plays an important role in energy regulation via endocrine, paracrine and autocrine signals as results of obesity due to accumulation of adipose tissue to excess that by time affects negatively both physical and psychological health and well being, it has been found that adipose tissues produces a variety of factors known as "adipokines" which play a key role in the development and progression of the disease and also hypothesized that adipokines are a possible link between obesity and the other risk components of the Metabolic syndrome. Many of the adipokines exert multiple actions in a variety of cellular processes leading to a complex array of abnormal characteristic of Metabolic syndrome. Abnormal production of these adipokines by expanded visceral fat during Adiposity contributes to a pro-inflammatory state. Increasing evidence suggests that aberrant production/release of adipokine from adipocyte i.e. adiponectin, leptin and resistin etc, may contribute to the health problems associated with Adiposity such as dyslipidemia, insulin resistance and atherosclerosis. This study conclusively have shown a significant role of adipokines secreted by adipose tissue and various metabolic risk markers play a important role in the development of Metabolic syndrome.

Dynamic and tissue-specific proteolytic processing of chemerin in obese mice

Chemerin is a chemoattractant involved in immunity as well as an adipokine, whose activity is regulated by successive proteolytic cleavages at its C-terminus. Chemerin’s C-terminal sequence and its proteolytic cleavage sites are highly conserved between human and mouse, as well as in other species. We produced, purified and characterized different mouse chemerin forms. Ca²⁺ mobilization assay showed that the EC₅₀ values for mchem161T and mchem157R were 135.8 ± 158 nM and 71.2 ± 55.4 nM, respectively, whereas mchem156S and mchem155F had a 20-fold higher potency with an EC₅₀ of 4.6 ± 1.8 nM and 3.6 ± 3.0 nM, respectively, likely representing the two physiologically active forms of chemerin. No agonist activity was found for mchem154A. Similar results were obtained in a chemotaxis assay. To identify and quantify the in vivo mouse chemerin forms in biological samples, we developed specific ELISAs for mchem162K, mchem157R, mchem156S, mchem155F and mchem154A, using antibodies raised against peptides from the C-terminus of the different mouse chemerin forms. The prochemerin form, mchem162K, was the major chemerin form in plasma with its increase matching the increase of total plasma chemerin in obese mice. During the onset of obesity in high-fat diet fed mice, mchem156S was elevated in plasma. In contrast, mchem155F was the dominant form in epididymal fat extracts. Our study provides the first direct evidence that mouse chemerin undergoes extensive, dynamic and tissue-specific proteolytic processing in vivo, similar to human chemerin, underlining the importance of measuring individual chemerin forms in studies of chemerin biology in mouse models.

Association Between Obesity and Weight Change and Risk of Diverticulitis in Women

BACKGROUND & AIMS

There is little evidence that adiposity associates with diverticulitis, especially among women. We conducted a comprehensive evaluation of obesity, weight change, and incidence of diverticulitis in a large cohort of women.

METHODS

We conducted a prospective cohort study of 46,079 women enrolled in the Nurses' Health Study who were 61-89 years old and free of diverticulitis, diverticular bleeding, cancers, or inflammatory bowel disease at baseline (in 2008). We used Cox proportional hazards models to examine the associations among risk of incident diverticulitis and body mass index (BMI), waist circumference, waist to hip ratio, and weight change from age 18 years to the present. The primary end point was first incident diverticulitis requiring antibiotic therapy or hospitalization.

RESULTS

We documented 1084 incident cases of diverticulitis over 6 years of follow-up, encompassing 248,001 person-years. After adjustment for other risk factors, women with a BMI ≥35.0 kg/m2 had a hazard ratio for diverticulitis of 1.42 (95% confidence interval [CI], 1.08-1.85) compared to women with a BMI <22.5 kg/m2. Compared to women in the lowest quintile, the multivariable hazard ratios among women in the highest quintile were 1.35 (95% CI, 1.02-1.78) for waist circumference and 1.40 (95% CI, 1.07-1.84) for waist to hip ratio; these associations were attenuated with further adjustment for BMI. Compared to women maintaining weight from age 18 years to the present, those who gained ≥20 kg had a 73% increased risk of diverticulitis (95% CI, 27%-136%).

CONCLUSIONS

During a 6-year follow-up period, we observed an association between obesity and risk of diverticulitis among women. Weight gain during adulthood was also associated with increased risk.

Adipose depot-specific effects of ileal interposition surgery in UCD-T2D rats: unexpected implications for obesity and diabetes

Ileal interposition (IT) surgery delays the onset of diabetes in a rat model of type-2 diabetes (UCD-T2DM). Here, to gain a deeper understanding of the molecular events underlying the effects of IT surgery, we examined the changes in the proteome of four white adipose depots (retroperitoneal, mesenteric, inguinal, and epididymal) and plasma-free fatty acid profile in pre-diabetic rats 1.5 months following IT or sham surgery. The IT-mediated changes were exerted mainly in mesenteric fat and spanned from delayed adipocyte maturation to a neuroendocrine remodeling. Conversely, inguinal, retroperitoneal, and epididymal depots showed opposite trends consistent with increased adipocyte maturation and adipogenesis development prior to overt signs of diabetes, probably orchestrated by peroxisome proliferator-activated receptor gamma signaling and higher plasma n-6/n-3 free fatty acid ratios. The resulting scenario suggests a targeted use of surgical strategies that seek to delay or improve diabetes in order to manipulate adipose depot-specific responses to maximize the duration and beneficial effects of the surgery.

Physiological and metabolic differences between visceral and subcutaneous adipose tissues in Nile tilapia (Oreochromis niloticus)

Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SCAT) have different structures and metabolic functions and play different roles in the regulation of the mammal endocrine system. However, little is known about morphology and physiological and metabolic functions between VAT and SCAT in fish. We compared the morphological, physiological, and biochemical characteristics of VAT and SCAT in Nile tilapia and measured their functions in energy intake flux, lipolytic ability, and gene expression patterns. SCAT contained more large adipocytes and nonadipocytes than VAT in Nile tilapia. VAT had higher lipid content and was the primary site for lipid deposition. Conversely, SCAT had higher hormone-induced lipolytic activity. Furthermore, SCAT had a higher percentage of monounsaturated and lower polyunsaturated fatty acids than VAT. SCAT had higher mitochondrial DNA, gene expression for fatty acid β-oxidation, adipogenesis, and brown adipose tissue characteristics, but it also had a lower gene expression for inflammation and adipocyte differentiation than VAT. SCAT and VAT have different morphological structures, as well as physiological and metabolic functions in fish. VAT is the preferable lipid deposition tissue, whereas SCAT exhibits higher lipid catabolic activity than VAT. The physiological functions of SCAT in fish are commonly overlooked. The present study indicates that SCAT has specific metabolic characteristics that differ from VAT. The differences between VAT and SCAT should be considered in future metabolism studies using fish as models, either in biomedical or aquaculture studies.

The 24-Month Changes in Body Fat Mass and Adipokines in Patients Starting Peritoneal Dialysis

♦ BACKGROUND: Peritoneal dialysis (PD) is characterized by a gain in fat mass. The fat tissue is a complex endocrine organ that releases various adipokines. In this study, we prospectively examined serial changes of fat composition and adipokines in patients undergoing PD. ♦ METHODS: Body composition was assessed by computed tomography (CT). Nutrition status and adipokines (leptin, adiponectin, interleukin [IL]-6, and tumor necrosis factor [TNF]-α) were assessed on the 7th day and 6 months, 12 months, and 24 months after the start of PD. ♦ RESULTS: Fifty-four patients (28 men), with a mean age of 53.2 ± 13.2 years, were enrolled. Baseline fat mass, especially subcutaneous fat mass, was correlated with baseline leptin (ρ = 0.612), adiponetin (ρ = -0.477), and interleukin-6 (IL-6) (ρ = 0.391). Visceral fat mass was correlated with leptin (ρ = 0.545) and adiponectin (ρ = -0.514). Baseline adiponectin was negatively correlated with baseline leptin (ρ = -0.363). While body weight and leptin increased during the 24 months, serum adiponectin decreased in that period. The changes in visceral and subcutaneous fat mass were greater in the first 12 months and 6 months, respectively. There was no difference in IL-6 and TNF-α. Eight patients died during the follow-up period (mean 47.4 months). Twenty-seven patients continued PD. Increased baseline and serial change of IL-6 level were risk factors for mortality. After adjusting for age, sex, diabetes mellitus (DM), and coronary vascular disease (CVD), the significance of the IL-6 level disappeared. ♦ CONCLUSIONS: Baseline subcutaneous fat in patients starting PD is correlated with baseline adipokine levels rather than visceral fat. The increase in subcutaneous fat was greatest in the first 6 months. While leptin and adiponectin increased and decreased respectively, IL-6 did not change in the first 24 months.

Inflammation mediates the association between visceral adiposity and obstructive sleep apnea in adolescents

Only a handful of studies, primarily in clinical samples, have reported an association between obesity, inflammation, and obstructive sleep apnea (OSA) in children and adolescents. No studies, however, have examined the pathogenetic link between visceral adiposity, systemic inflammation, and incident OSA in a large general population sample using objective measures of sleep and body fat. Adolescents (n = 392; mean age 17.0 ± 2.2 yr, 54.0% male) from the Penn State Child Cohort (PSCC) underwent 9-h overnight polysomnography; a DXA scan to assess body fat distribution; and a single fasting blood draw for the assessment of plasma interleukin-6 (IL-6), IL-6 soluble receptor (IL-6 sR), tumor necrosis factor alpha (TNFα), tumor necrosis factor receptor 1A (TNFR1), C-reactive protein (CRP), leptin, and adiponectin levels via ELISA. Visceral fat area was significantly elevated in moderate OSA (AHI ≥ 5), especially in boys. IL-6, CRP, and leptin were highest in adolescents with moderate OSA, even after adjusting for BMI percentile. Mediation analysis revealed that 42% of the association between visceral fat and OSA in adolescents was mediated by IL-6 (p = 0.03), while 82% of the association was mediated by CRP (p = 0.01). These data are consistent with the model of a feed-forward, vicious cycle, in which the release of proinflammatory cytokines by visceral adipocytes largely explains the association between central obesity and OSA; in turn, inflammation is also elevated in OSA independent of BMI. These findings, in a large, representative, non-clinical sample of young people, add to our understanding of the developmental pathogenesis of sleep apnea.

Characterization of visceral and subcutaneous adipose tissue transcriptome in pregnant women with and without spontaneous labor at term: implication of alternative splicing in the metabolic adaptations of adipose tissue to parturition

OBJECTIVE

The aim of this study was to determine gene expression and splicing changes associated with parturition and regions (visceral vs. subcutaneous) of the adipose tissue of pregnant women.

STUDY DESIGN

The transcriptome of visceral and abdominal subcutaneous adipose tissue from pregnant women at term with (n=15) and without (n=25) spontaneous labor was profiled with the Affymetrix GeneChip Human Exon 1.0 ST array. Overall gene expression changes and the differential exon usage rate were compared between patient groups (unpaired analyses) and adipose tissue regions (paired analyses). Selected genes were tested by quantitative reverse transcription-polymerase chain reaction.

RESULTS

Four hundred and eighty-two genes were differentially expressed between visceral and subcutaneous fat of pregnant women with spontaneous labor at term (q-value <0.1; fold change >1.5). Biological processes enriched in this comparison included tissue and vasculature development as well as inflammatory and metabolic pathways. Differential splicing was found for 42 genes [q-value <0.1; differences in Finding Isoforms using Robust Multichip Analysis scores >2] between adipose tissue regions of women not in labor. Differential exon usage associated with parturition was found for three genes (LIMS1, HSPA5, and GSTK1) in subcutaneous tissues.

CONCLUSION

We show for the first time evidence of implication of mRNA splicing and processing machinery in the subcutaneous adipose tissue of women in labor compared to those without labor.

Obesity-related glomerulopathy: clinical and pathologic characteristics and pathogenesis

The prevalence of obesity-related glomerulopathy is increasing in parallel with the worldwide obesity epidemic. Glomerular hypertrophy and adaptive focal segmental glomerulosclerosis define the condition pathologically. The glomerulus enlarges in response to obesity-induced increases in glomerular filtration rate, renal plasma flow, filtration fraction and tubular sodium reabsorption. Normal insulin/phosphatidylinositol 3-kinase/Akt and mTOR signalling are critical for podocyte hypertrophy and adaptation. Adipokines and ectopic lipid accumulation in the kidney promote insulin resistance of podocytes and maladaptive responses to cope with the mechanical forces of renal hyperfiltration. Although most patients have stable or slowly progressive proteinuria, up to one-third develop progressive renal failure and end-stage renal disease. Renin-angiotensin-aldosterone blockade is effective in the short-term but weight loss by hypocaloric diet or bariatric surgery has induced more consistent and dramatic antiproteinuric effects and reversal of hyperfiltration. Altered fatty acid and cholesterol metabolism are increasingly recognized as key mediators of renal lipid accumulation, inflammation, oxidative stress and fibrosis. Newer therapies directed to lipid metabolism, including SREBP antagonists, PPARα agonists, FXR and TGR5 agonists, and LXR agonists, hold therapeutic promise.

Relationships between Rodent White Adipose Fat Pads and Human White Adipose Fat Depots

The objective of this review was to compare and contrast the physiological and metabolic profiles of rodent white adipose fat pads with white adipose fat depots in humans. Human fat distribution and its metabolic consequences have received extensive attention, but much of what has been tested in translational research has relied heavily on rodents. Unfortunately, the validity of using rodent fat pads as a model of human adiposity has received less attention. There is a surprisingly lack of studies demonstrating an analogous relationship between rodent and human adiposity on obesity-related comorbidities. Therefore, we aimed to compare known similarities and disparities in terms of white adipose tissue (WAT) development and distribution, sexual dimorphism, weight loss, adipokine secretion, and aging. While the literature supports the notion that many similarities exist between rodents and humans, notable differences emerge related to fat deposition and function of WAT. Thus, further research is warranted to more carefully define the strengths and limitations of rodent WAT as a model for humans, with a particular emphasis on comparable fat depots, such as mesenteric fat.

Identification of Mouse Mesenteric and Subcutaneous in vitro Adipogenic Cells

Fat accumulation and the dysfunction of visceral white adipose tissue (WAT), but not subcutaneous WAT, cause abnormalities in whole body metabolic homeostasis. However, no current drugs specifically target visceral WAT. The primary reason for this is that a practical in vitro culture system for mesenteric adipocytes has not been established. To resolve this issue, we sought to identify in vitro adipogenic cells in mesenteric and subcutaneous WATs. First, we examined the expression pattern of surface antigens in stromal-vascular fraction (SVF) cells from mouse mesenteric and subcutaneous WATs, and found the expression of 30 stem cell-related surface antigens. Then, to evaluate the adipogenic ability of each fraction, we performed in vitro screening, and identified five candidate markers for mesenteric adipogenic cells and one candidate marker for subcutaneous adipogenic cells. To investigate whether in vitro adipogenic ability accurately reflects the conditions in vivo, we performed transplantation experiments, and identified CD9(-) CD201(+) Sca-1(-) cells and CD90(+) cells as mesenteric and subcutaneous in vitro adipogenic cells, respectively. Furthermore, mature adipocytes derived from mesenteric and subcutaneous adipogenic cells maintained each characteristic phenotype in vitro. Thus, our study should contribute to the development of a useful culture system for visceral adipocytes.

Characterization of Visceral and Subcutaneous Adipose Tissue Transcriptome and Biological Pathways in Pregnant and Non-Pregnant Women: Evidence for Pregnancy-Related Regional-Specific Differences in Adipose Tissue

Objective

The purpose of this study was to compare the transcriptome of visceral and subcutaneous adipose tissues between pregnant and non-pregnant women.

Study Design

The transcriptome of paired visceral and abdominal subcutaneous adipose tissues from pregnant women at term and matched non-pregnant women (n = 11) was profiled with the Affymetrix Human Exon 1.0 ST array. Differential expression of selected genes was validated with the use of quantitative reverse transcription–polymerase chain reaction.

Results

Six hundred forty-four transcripts from 633 known genes were differentially expressed (false discovery rate (FDR) <0.1; fold-change >1.5), while 42 exons from 36 genes showed differential usage (difference in FIRMA scores >2 and FDR<0.1) between the visceral and subcutaneous fat of pregnant women. Fifty-six known genes were differentially expressed between pregnant and non-pregnant subcutaneous fat and three genes in the visceral fat. Enriched biological processes in the subcutaneous adipose tissue of pregnant women were mostly related to inflammation.

Conclusion

The transcriptome of visceral and subcutaneous fat depots reveals pregnancy-related gene expression and splicing differences in both visceral and subcutaneous adipose tissue. Furthermore, for the first time, alternative splicing in adipose tissue has been associated with regional differences and human parturition.

Anthropometric, cardiovascular and functional variables as indicators of health related physical fitness in university professors

AbstractObjective To verify the behavior of anthropometric, cardiovascular and functional variables as indicators of health-related physical fitness in university professors and perform a comparison of these variables between sexes.Materials and methods We conducted an observational epidemiological cross-sectional study in 145 professors (45.86 ± 9.7 years), 103 men (71.03%), which were evaluated by measuring heart rate (HR) and systolic (SBP) and diastolic (DBP) pressure at rest, body weight, height, body mass index (BMI), body fat percentage (BF%), handgrip strength (HGS), flexibility and cardiorespiratory fitness (CRF). We proceeded to the descriptive analysis, Student t-test for comparison between sexes and multiple regression analysis to verify the association between the variables analyzed. It was adopted a significance level of p < 0.05.Results The sex affected all variables. Women had better levels of BMI, flexibility, SBP and DBP. The BF% and CRF were associated with SBP and BMI in both sexes.Conclusion The behavior of anthropometric, cardiovascular and functional variables indicated unsatisfactory values for flexibility, HGS and BMI, with the worst levels among men. Furthermore, the variables that showed better association with HRPF were BF% and CRF.

North American ginseng influences adipocyte-macrophage crosstalk regulation of inflammatory gene expression

Background

Adipocyte–macrophage communication plays a critical role regulating white adipose tissue (WAT) inflammatory gene expression. Because WAT inflammation contributes to the development of metabolic diseases, there is significant interest in understanding how exogenous compounds regulate the adipocyte–macrophage crosstalk. An aqueous (AQ) extract of North American (NA) ginseng (Panax quinquefolius) was previously shown to have strong inflammo-regulatory properties in adipocytes. This study examined whether different ginseng extracts influence adipocyte–macrophage crosstalk, as well as WAT inflammatory gene expression.

Methods

The effects of AQ and ethanol (EtOH) ginseng extracts (5 μg/mL) on adipocyte and macrophage inflammatory gene expression were studied in 3T3-L1 and RAW264.7 cells, respectively, using real-time reverse transcription polymerase chain reaction. Adipose tissue organ culture was also used to examine the effects of ginseng extracts on epididymal WAT (EWAT) and inguinal subcutaneous WAT (SWAT) inflammatory gene expression.

Results

The AQ extract caused significant increases in the expression of common inflammatory genes (e.g., Mcp1, Ccl5, Tnf-α, Nos2) in both cell types. Culturing adipocytes in media from macrophages treated with the AQ extract, and vice versa, also induced inflammatory gene expression. Adipocyte Ppar-γ expression was reduced with the AQ extract. The AQ extract strongly induced inflammatory gene expression in EWAT, but not in SWAT. The EtOH extract had no effect on inflammatory gene expression in either both cell types or WAT.

Conclusion

These findings provide important new insights into the inflammo-regulatory role of NA ginseng in WAT.

Relationship between obesity and coronary heart disease among urban Bangladeshi men and women

The aim of the study was to examine the association of different measures of obesity (body mass index or BMI, waist circumference or WC, waist to hip ratio or WHR and waist height ratio or WHtR) with coronary heart disease (CHD) in a Bangladeshi population. The study included 189 hospitalized CHD cases (133 men and 52 women) and 201 controls (137 men and 68 women). Logistic regression was done to assess the associations between obesity and CHD. The mean age was 53.1 ± 8.3 for men and 51.9 ± 8.4 for women. After adjustment for confounders the odds ratio (OR) of CHD for men was 1.69 (95% CI, 1.24-2.32), 1.94 (95% CI 1.40-2.70), and 1.32 (95% CI, 1.01-2.16) per 1 standard deviation (SD) increase in BMI, WC, and WHtR respectively. The OR for women was 2.64 (CI, 1.61-4.34), 1.82 (95% CI 1.12-2.95), 2.32 (95% CI, 1.36-3.96), and 1.94 (95% CI, 1.23-3.07) per 1 SD increase in BMI, WC, WHtR and WHR respectively. Since both total obesity and abdominal adiposity were associated with development of CHD and since measurement of WC and BMI are inexpensive, both should be included in the clinical setting for CHD risk assessment for this group of population.

A little sugar goes a long way: the cell biology of O-GlcNAc

Unlike the complex glycans decorating the cell surface, the O-linked β-N-acetyl glucosamine (O-GlcNAc) modification is a simple intracellular Ser/Thr-linked monosaccharide that is important for disease-relevant signaling and enzyme regulation. O-GlcNAcylation requires uridine diphosphate-GlcNAc, a precursor responsive to nutrient status and other environmental cues. Alternative splicing of the genes encoding the O-GlcNAc cycling enzymes O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) yields isoforms targeted to discrete sites in the nucleus, cytoplasm, and mitochondria. OGT and OGA also partner with cellular effectors and act in tandem with other posttranslational modifications. The enzymes of O-GlcNAc cycling act preferentially on intrinsically disordered domains of target proteins impacting transcription, metabolism, apoptosis, organelle biogenesis, and transport.

Short-term food restriction followed by controlled refeeding promotes gorging behavior, enhances fat deposition, and diminishes insulin sensitivity in mice

Rodents are commonly used in food restriction refeeding studies to investigate weight regain. Mice that are rationed food every 24 h may consume all allocated food in a short time (gorge) and therefore undergo a brief well-fed period followed by an extended fasted period until the next day's food allotment. These exaggerated metabolic states are not typical in mice fed ad libitum (nibbling). The aim of the current study was to elucidate the intraday and cumulative metabolic consequences of gorging (induced by food restriction) in mice during controlled refeeding. Accordingly, following a temporary food restriction, mice were fed rations similar to intakes of controls fed ad libitum. Temporary food restriction initiated gorging behavior that persisted during refeeding; consequently, metabolism-related measurements were obtained in the gorging mice during their daily fed and fasted metabolic states. Robust differences in adipose tissue lipogenic and inflammatory gene expression were found in the gorging mice by metabolic state (fed versus fasted). Additionally, despite a reduced cumulative food intake compared to mice fed ad libitum, restriction-induced gorging mice had increased intraabdominal fat accumulation, diminished hepatic and peripheral insulin sensitivity, and a gene expression profile favoring lipid deposition. Our findings highlight the intraday differences in gene expression in gorging mice before and after feeding that confound comparisons with mice fed ad libitum, or nibbling. The present study also provides evidence that weight regain following food restriction is associated with cumulative metabolic and behavioral abnormalities in mice.

IL-6 gene expression in adipose tissue of postmenopausal women and its association with metabolic risk factors

Adipose tissue secretes various kinds of adipokines that controls the glucose and lipid metabolism in humans. The abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) both are associated with metabolic syndrome and insulin resistance. IL-6 is one of the adipokines, which promotes insulin resistance and dyslipidemia in humans. The association of adipokines with metabolic syndrome at protein levels are well documented. However, their association at gene expression level are lacking. The present study was design to investigate IL-6 mRNA expression in adipose tissues (VAT and SAT) and its correlation with metabolic risk factors and insulin resistance (HOMA) in post menopausal women. A total of 108 Asian North Indian post menopausal women, 54 without metabolic syndrome (controls) and 54 with metabolic syndrome (cases) were recruited and evaluated. Overnight fasting blood samples were collected at admission and abdominal visceral and subcutaneous adipose tissues were collected during open abdomen surgery. The results showed significantly (p < 0.05 or p < 0.01 or p < 0.001) higher mean SBP, glucose, insulin, HOMA, TG, VLDL and serum IL-6 while significantly (p < 0.001) lower HDL and estrogen in cases as compared to controls. In cases, the relative mean SAT IL-6 expression was also significantly (p < 0.05) higher as compared to VAT. Further, in cases, the VAT IL-6 expression showed significant (p < 0.05 or p < 0.001) and negative correlation with WC, WHR, glucose, HOMA, TC, LDL and estrogen while SAT IL-6 expression also showed significant (p < 0.05 or p < 0.01 or p < 0.001) and negative correlation with WC, WHR and estrogen. The Cox regression analysis found VAT IL-6 mRNA expression the significant (p < 0.05 or p < 0.01) an independent predictor of WC, HOMA, TC, LDL and estrogen while SAT IL-6 mRNA expression the significant (p < 0.01) an independent predictor of TG and VLDL. The study concluded that IL-6 expressions of both visceral and subcutaneous tissues may be associated with metabolic risk factors in postmenopausal Asian North Indian women.

Pregnancy complicated by obesity induces global transcript expression alterations in visceral and subcutaneous fat

Maternal obesity is a significant risk factor for development of both maternal and fetal metabolic complications. Increase in visceral fat and insulin resistance is a metabolic hallmark of pregnancy, yet not much is known how obesity alters adipose cellular function and how this may contribute to pregnancy morbidities. We sought to identify alterations in genome-wide transcription expression in both visceral (omental) and abdominal subcutaneous fat deposits in pregnancy complicated by obesity. Visceral and abdominal subcutaneous fat deposits were collected from normal weight and obese pregnant women (n = 4/group) at the time of scheduled uncomplicated cesarean section. A genome-wide expression array (Affymetrix Human Exon 1.0 st platform), validated by quantitative real-time PCR, was utilized to establish the gene transcript expression profile in both visceral and abdominal subcutaneous fat in normal weight and obese pregnant women. Global alteration in gene expression was identified in pregnancy complicated by obesity. These regions of variations led to identification of indolethylamine N-methyltransferase, tissue factor pathway inhibitor-2, and ephrin type-B receptor 6, not previously associated with fat metabolism during pregnancy. In addition, subcutaneous fat of obese pregnant women demonstrated increased coding protein transcripts associated with apoptosis as compared to lean counterparts. Global alteration of gene expression in adipose tissue may contribute to adverse pregnancy outcomes associated with obesity.

Pioglitazone upregulates angiotensin converting enzyme 2 expression in insulin-sensitive tissues in rats with high-fat diet-induced nonalcoholic steatohepatitis

Background and Aim. Thiazolidinediones (TZDs) can improve hepatic steatosis in nonalcoholic steatohepatitis (NASH). Angiotensin (Ang) II, the primary effector of renin-angiotensin system (RAS), plays vital roles in the development and progression of NASH. And some AngII-mediated effects can be regulated by TZDs. Angiotensin-converting enzyme (ACE) 2, a new component of RAS, can degrade Ang II to attenuate its subsequent physiological actions. We aimed to evaluate the effects of TZDs on ACE2 expression in insulin-sensitive tissues in NASH rats. Methods. Forty rats were divided into the normal control, high-fat diet (HFD), pioglitazone control, and HFD plus pioglitazone groups. After 24 weeks of treatment, we evaluated changes in liver histology and tissue-specific ACE2 expression. Results. ACE2 gene and protein expression was significantly greater in liver and adipose tissue in the HFD group compared with normal control group, while was significantly reduced in skeletal muscle. Pioglitazone significantly reduced the degree of hepatic steatosis compared with the HFD group. Pioglitazone significantly increased ACE2 protein expression in liver, adipose tissue, and skeletal muscle compared with the HFD group. Conclusions. Pioglitazone improves hepatic steatosis in the rats with HFD-induced NASH and upregulates ACE2 expression in insulin-sensitive tissues.

Abdominal obesity, independent from caloric intake, accounts for the development of intestinal tumors in Apc(1638N/+) female mice

To determine whether visceral fat (VF), independent of other confounders, is causally linked to intestinal tumorigenesis, we surgically removed visceral fat in Apc(1638/N+) mice. At 15 weeks of age, male and female Apc(1638/N+) mice were randomized to one of three groups: ad libitum, visceral fat removal (VF-) and ad libitum fed, or caloric restriction, and were studied for effects on tumorigenesis and survival. As compared with ad libitum, VF- and caloric restriction reduced macroadenomas to a similar extent (P < 0.05), but only caloric restriction significantly improved survival (P < 0.05). Given that a significant group × gender interaction was observed, we next examined males and females separately. In females, macroadenomas were markedly attenuated by VF- (1.33 ± 0.23 mean ± SE; P < 0.05), but not by caloric restriction (2.35 ± 0.25; P = 0.71), as compared with ad libitum (2.50 ± 0.34). In males, however, caloric restriction (1.71 ± 0.26; P < 0.01), but not VF- (2.94 ± 0.42; P = 0.29), reduced macroadenomas, as compared with ad libitum males (3.47 ± 0.30). In females, both VF- (P = 0.05) and caloric restriction (P < 0.01) improved survival, but not in male mice (P = 0.15). The benefits observed with caloric restriction were consistent with favorable metabolic adaptations, but protection conferred in VF- females was despite lower adiponectin levels (P < 0.05), and failure to reduce body mass, total adiposity, glucose, insulin, leptin, and chemokine (C-X-C motif) ligand 1 (CXCL-1) levels. In conclusion, these data provide the first causal evidence linking visceral fat to intestinal cancer risk, and suggest that factors, other than known metabolic mediators, may impact tumor development. Furthermore, these data emphasize that strategies designed to deplete visceral fat stores in humans should be considered in the prevention of intestinal cancer. Cancer Prev Res; 6(3); 177-87. ©2012 AACR.

Plasma 8-isoprostane concentrations and adipogenic and adipokine gene expression patterns in subcutaneous and mesenteric adipose tissues of fattening Wagyu cattle

We hypothesized that fattening Wagyu cattle fed conventional low-vitamin fattening diets are exposed to oxidative stress. In this experiment, we studied the plasma concentrations of 8-isoprostane and the fat depot-specific effects of the diet-induced adipogenic (C/EBPβ, C/EBPδ, C/EBPα and PPARγ2) and adipokine (VEGF, FGF-2, leptin and adiponectin) gene expressions in fattening Wagyu steers. Animals were fed a high-vitamin (α-tocopherol and β-carotene) diet (HV) or a control diet (CT) during the fattening period (from 10 to 30 months of age). The plasma concentrations of 8-isoprostane, a marker of oxidative stress, were significantly lower in the HV group than in the CT group. In mesenteric adipose tissue, the expressions of the adipogenic and adipokine genes in the HV group were significantly lower than those in the CT group. In contrast, there were no differences in the expression of the adipogenic and adipokine genes in subcutaneous adipose tissue between groups. These results suggest that higher intake of dietary α-tocopherol and β-carotene affects the expression patterns of adipogenic and adipokine genes in a fat depot-specific manner with the reduction of plasma 8-isoprostane concentrations.

Does body fat mass define survival in patients starting peritoneal dialysis?

BACKGROUND AND AIMS

Peritoneal dialysis (PD) is characterized by a gain in fat mass. Unlike subcutaneous fat, visceral fat is associated with metabolic syndrome and survival. We prospectively examined whether visceral or subcutaneous fat could predict outcome in patients undergoing PD.

METHODS

We studied 117 new patients (57 men) undergoing PD between February 2006 and November 2011. Baseline body composition was measured on computed tomograms. Visceral obesity was defined as a visceral fat area exceeding 100 cm(2), and subcutaneous obesity, as a subcutaneous fat area exceeding 130 cm(2).

RESULTS

Among the 117 patients, 37 and 29 were diagnosed with visceral and subcutaneous obesity respectively. Visceral and subcutaneous obesity were both present in 21 patients. In the study population, the 1-year and 5-year survival rates were 94% and 59%. The rates of peritonitis and exit-infection were 0.31 and 0.14 episodes per patient-year. Mortality was greater in patients with visceral obesity than in those without visceral obesity (p = 0.005). Visceral obesity had no influence on peritonitis and exit-infection rates. Subcutaneous obesity was associated neither with survival nor with peritonitis or exit-site infection. In a multivariate Cox regression analysis, visceral obesity was not a risk factor for poor outcome.

CONCLUSIONS

Increased visceral fat at PD initiation is not an independent predictor of poor survival. Any impact of visceral or subcutaneous fat mass on outcomes in patients undergoing PD would be better defined by larger, long-term studies.

Interleukin-1 beta: a potential link between stress and the development of visceral obesity

Background

A disproportionate amount of body fat within the abdominal cavity, otherwise known as visceral obesity, best predicts the negative health outcomes associated with high levels body fat. Growing evidence suggests that repeated activation of the stress response can favor visceral fat deposition and that visceral obesity may induce low-grade, systemic inflammation which is etiologically linked to the pathogenesis of obesity related diseases such as cardiovascular disease and type 2 diabetes. While the obesity epidemic has fueled considerable interest in these obesity-related inflammatory diseases, surprisingly little research is currently focused on understanding the functions of inflammatory proteins in healthy, non-obese white adipose tissue (WAT) and their possible role in modulating stress-induced shifts in body fat distribution.

Hypothesis

The current review presents evidence in support the novel hypothesis that stress-evoked interleukin-1 beta (IL-1β) signaling within subcutaneous adipose tissue, when repeatedly induced, contributes toward the development of visceral obesity. It is suggested that because acute stressor exposure differentially increases IL-1β levels within subcutaneous adipose relative to visceral adipose tissue in otherwise healthy, non-obese rats, repeated induction of this response may impair the ability of subcutaneous adipose tissue to uptake energy substrates, synthesize and retain triglycerides, and/or adapt to positive energy balance via hyperplasia. Consequently, circulating energy substrates may be disproportionately shunted to visceral adipose tissue for storage, thus driving the development of visceral obesity.

Conclusions

This review establishes the following key points: 1) body fat distribution outweighs the importance of total body fat when predicting obesity-related disease risk; 2) repeated exposure to stress can drive the development of visceral obesity independent of changes in body weight; 3) because of the heterogeneity of WAT composition and function, an accurate understanding of WAT responses requires sampling multiple WAT depots; 4) acute, non-pathogenic stressor exposure increases WAT IL-1β concentrations in a depot specific manner suggesting an adaptive, metabolic role for this cytokine; however, when repeated, stress-induced IL-1β in non-visceral WAT may result in functional impairments that drive the development of stress-induced visceral obesity.

Food restriction and refeeding induces changes in lipid pathways and fat deposition in the adipose and hepatic tissues in rats with diet-induced obesity

The aim of this study was to determine the effects of successive cycles of a moderately restrictive diet and refeeding with a high-fat diet on the metabolism of the adipose and hepatic tissues of obese rats. Rats were assigned to the following groups: a chow diet; a high-fat diet; a moderate caloric restriction; or a moderate caloric restriction plus refeeding. Some animals in each group were given [1-(14)C]triolein intragastrically, while others received an intraperitoneal injection of 3 mCi (3)H(2)O. All animals were killed by decapitation. The retroperitoneal, visceral epididymal and omental white adipose tissues, brown adipose tissue, liver and blood were immediately removed. The lipid uptake from the diet, in vivo rate of lipogenesis, percentage of fat, lipid profile and leptin concentration were analysed. The high-fat diet promoted an increase in fatty liver (P ≤ 0.05), adiposity mass (P ≤ 0.05) and the plasma concentration of leptin (P ≤ 0.05) and a decreased lipid uptake in white adipose tissue depots (P ≤ 0.05) in relation to the chow diet. The moderate caloric restriction did not reverse the changes promoted by the high-fat diet but induced a small decrease in adiposity, which was reversed after refeeding, and the animals maintained a dyslipidaemic profile and high fat deposition in the liver. We can conclude that the high-fat diet and subsequent moderate caloric restriction plus refeeding increased the risks of developing visceral obesity, dyslipidaemia and non-alcoholic fatty liver disease, which suggests that this type of experimental protocol can be used to study mechanisms related to the metabolic syndrome.

Perinephric and epididymal fat affect hepatic metabolism in rats

The present study examined whether the perinephric and epididymal visceral fat (PEVF) depot under short-term excess nutrient protected the liver by trapping nutrient-derived nonesterified free fatty acids (NEFAs) or had deleterious effects on hepatic triglycerides (TGs) accumulation and insulin resistance due to adipokine secretion. Young rats pre-emptively underwent surgical PEVF removal or sham operations and were fed with either high-fat diet (HFD) (PEVF-HFD) or regular chow (RC) (PEVF-RC) for 3 days. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp. Liver TG, serum NEFA, and fat-derived adipokines were assessed. Insulin and lipogenesis signaling were assessed by western blots. Pre-emptive PEVF removal significantly decreases insulin-induced suppression of hepatic glucose production (HGP) both in RC and in HFD-fed rats. In accordance with the clamp results, hepatic TG accumulation is also significantly reduced by PEVF excision both in RC and HFD-fed rats. These results are further validated by insulin signaling results, which show that pre-emptive PEVF removal increases phosphorylation of hepatic Akt, irrespective of diet. Notably, high levels of serum leptin induced by HFD are significantly reduced by pre-emptive PEVF excision. Additionally, expression of lipogenic enzyme p-acetyl-CoA-carboxylase, denoting reduced lipogenesis, is increased in the PEVF-HFD rats. In conclusion, PEVF has a deleterious effect on the liver as a source of insulin resistance-inducing adipokines irrespective of diet, and does not serve as a buffer for excess nutrients.

Role of transcription factor modifications in the pathogenesis of insulin resistance

Non-alcoholic fatty liver disease (NAFLD) is characterized by fat accumulation in the liver not due to alcohol abuse. NAFLD is accompanied by variety of symptoms related to metabolic syndrome. Although the metabolic link between NAFLD and insulin resistance is not fully understood, it is clear that NAFLD is one of the main cause of insulin resistance. NAFLD is shown to affect the functions of other organs, including pancreas, adipose tissue, muscle and inflammatory systems. Currently efforts are being made to understand molecular mechanism of interrelationship between NAFLD and insulin resistance at the transcriptional level with specific focus on post-translational modification (PTM) of transcription factors. PTM of transcription factors plays a key role in controlling numerous biological events, including cellular energy metabolism, cell-cycle progression, and organ development. Cell type- and tissue-specific reversible modifications include lysine acetylation, methylation, ubiquitination, and SUMOylation. Moreover, phosphorylation and O-GlcNAcylation on serine and threonine residues have been shown to affect protein stability, subcellular distribution, DNA-binding affinity, and transcriptional activity. PTMs of transcription factors involved in insulin-sensitive tissues confer specific adaptive mechanisms in response to internal or external stimuli. Our understanding of the interplay between these modifications and their effects on transcriptional regulation is growing. Here, we summarize the diverse roles of PTMs in insulin-sensitive tissues and their involvement in the pathogenesis of insulin resistance.

Hypertrophy-driven adipocyte death overwhelms recruitment under prolonged weight gain

Fat pads dynamically regulate energy storage capacity under energy excess and deficit. This remodeling process is not completely understood, with controversies regarding differences between fat depots and plasticity of adipose cell number. We examined changes of mouse adipose cell-size distributions in epididymal, inguinal, retroperitoneal, and mesenteric fat under both weight gain and loss. With mathematical modeling, we specifically analyzed the recruitment, growth/shrinkage, and loss of adipose cells, including the size dependence of these processes. We found a qualitatively universal adipose tissue remodeling process in all four fat depots: 1), There is continuous recruitment of new cells under weight gain; 2), the growth and shrinkage of larger cells (diameter >50 μm) is proportional to cell surface area; and 3), cell loss occurs under prolonged weight gain, with larger cells more susceptible. The mathematical model gives a predictive integrative picture of adipose tissue remodeling in obesity.