Diet-induced adiposity alters the serum profile of inflammation in C57BL/6N mice as measured by antibody array

Serum stromal cell-derived factor-1 concentrations are increased and associated with nonalcoholic fatty liver disease in children with obesity

INTRODUCTION

Stromal cell-derived factor-1 (SDF-1) is a newly discovered small molecule adipocytokine, and research has shown that it is closely related to the occurrence and development of obesity. However, there are currently few research reports on SDF-1 in childhood obesity and nonalcoholic fatty liver disease (NAFLD), and this study aims to explore the relationship between SDF-1 and obesity related indicators in obese children.

METHODS

Serum SDF-1 concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Clinical and biochemical data were collected, such as body mass index (BMI), waist and hip circumference, blood pressure, liver enzymes, cholesterol, and fasting insulin. Children with NAFLD or not were evaluated through Color Doppler Ultrasound.

RESULTS

Serum SDF-1 concentrations were significantly higher in obese subjects than in non-obese subjects (P < 0.05), and were elevated in the NAFLD obese subjects than in the non-NAFLD obese subjects (P < 0.05). SDF-1 was positively correlated with BMI, waist-to-hip ratio, systolic blood pressure, body fat percentage (BFP), basal metabolic rate (BMR), alanine transaminase (ALT), aspartate transaminase (AST), glutyltranspeptidase (GT), and homoeostasis model of HOMA-IR, independent of their uric acid (UA), total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), gender and age. BFP and BMR were associated with the serum SDF-1 concentrations in multivariable linear regression analysis.

CONCLUSION

These results suggest that SDF-1 levels are elevated in obese children and are associated with NAFLD, indicating that SDF-1 may play a role in the development of childhood obesity and metabolic disorders.

Impact of Obesity on the IL-6 Immune Marker and Th17 Immune Cells in C57BL/6 Mice Models with Imiquimod-Induced Psoriasis

Obese psoriatic patients experience higher disease severity and exhibit poorer treatment responses and clinical outcomes. It has been proposed that proinflammatory cytokines produced by adipose tissue exacerbate psoriasis; however, the role of obesity in psoriasis remains unclear. This study aimed to elucidate the role of obesity in the pathogenesis of psoriasis, focusing on immunological changes. To induce obesity, mice were fed a high-fat diet for 20 weeks. We then applied imiquimod to the skin on a mouse’s back for seven consecutive days to induce psoriasis and scored lesion severity every day for seven days. Cytokine levels in serum and the Th17 cell population in the spleen and draining lymph nodes were studied to identify immunological differences. The clinical severity was more remarkable, and histologically the epidermis was also significantly thicker in the obese group. Increased levels of IL-6 and TNF-α were observed in serum after psoriasis. They were elevated to a greater degree, with greater expansion of the functional Th17 cell population in the obese group. It is concluded that obesity could exacerbate psoriasis through mechanisms that involve elevated proinflammatory cytokine secretion and an expanded Th17 cell population.

Early Life Polychlorinated Biphenyl 126 Exposure Disrupts Gut Microbiota and Metabolic Homeostasis in Mice Fed with High-Fat Diet in Adulthood

Evidence supports the potential influence of persistent organic pollutants (POPs) on the pathogenesis and progression of obesity and diabetes. Diet-toxicant interactions appear to be important in diet-induced obesity/diabetes; however, the factors influencing this interaction, especially the early life environmental exposure, are unclear. Herein, we investigated the metabolic effects following early life five-day exposure (24 μg/kg body weight per day) to 3,3′,4,4′,5-pentacholorobiphenyl (PCB 126) at four months after exposure in mice fed with control (CTRL) or high-fat diet (HFD). Activation of aryl hydrocarbon receptor (AHR) signaling as well as higher levels of liver nucleotides were observed at 4 months after PCB 126 exposure in mice, independent of diet status. Inflammatory responses including higher levels of serum cytokines and adipose inflammatory gene expression caused by early life PCB 126 were observed only in HFD-fed mice in adulthood. Notably, early life PCB 126 exposure worsened HFD-induced impaired glucose homeostasis characterized by glucose intolerance and elevated gluconeogenesis and tricarboxylic acid (TCA) cycle flux without worsening the effects of HFD related to adiposity in adulthood. Furthermore, early life PCB 126 exposure resulted in diet-dependent changes in bacterial community structure and function later in life, as indicated by metagenomic and metabolomic analyses. These data contribute to a more comprehensive understanding of the interactions between diet and early life environmental chemical exposure.

Dietary fats modulate neuroinflammation in mucin 2 knock out mice model of spontaneous colitis

Specific diets regulate neuroimmune responses and modify risk of inflammatory bowel diseases, including ulcerative colitis. A link between gut and brain inflammation is also emerging. We hypothesized that adjusting dietary fatty acid composition modulates the neuroimmune responses in the mucin 2 knock out mice model of spontaneous colitis. Mice were randomly divided into three groups and fed isocaloric diets that only differed in their fatty acid composition. Diets enriched with anhydrous milk fat, corn oil, or Mediterranean diet fats were used. After nine weeks, brain and serum concentrations of ten inflammatory cytokines were measured. Three of these cytokines, including interleukin (IL)-2, IL-12 p70 and interferon-γ, were differentially expressed in the brains of animals from the three diet groups while there were no differences in the serum concentrations of these cytokines. Since only limited information is available about the functions of IL-2 in the central nervous system, in vitro experiments were performed to assess its effects on microglia. IL-2 had no effect on the secretion of neurotoxins and nitric oxide by microglia-like cells, but it selectively regulated phagocytic activity and reactive oxygen species production by stimulated microglia-like cells. Modulation of microglial reactive oxygen species through altered brain IL-2 concentrations could be one of the mechanisms linking diets with modified risk of neuroimmune disorders including Parkinson's disease.

Altered IGF-I activity and accelerated bone elongation in growth plates precede excess weight gain in a mouse model of juvenile obesity

Nearly one-third of children in the United States are overweight or obese by their preteens. Tall stature and accelerated bone elongation are characteristic features of childhood obesity, which cooccur with conditions such as limb bowing, slipped epiphyses, and fractures. Children with obesity paradoxically have normal circulating IGF-I, the major growth-stimulating hormone. Here, we describe and validate a mouse model of excess dietary fat to examine mechanisms of growth acceleration in obesity. We used in vivo multiphoton imaging and immunostaining to test the hypothesis that high-fat diet increases IGF-I activity and alters growth plate structure before the onset of obesity. We tracked bone and body growth in male and female C57BL/6 mice (n = 114) on high-fat (60% kcal fat) or control (10% kcal fat) diets from weaning (3 wk) to skeletal maturity (12 wk). Tibial and tail elongation rates increased after brief (1-2 wk) high-fat diet exposure without altering serum IGF-I. Femoral bone density and growth plate size were increased, but growth plates were disorganized in not-yet-obese high-fat diet mice. Multiphoton imaging revealed more IGF-I in the vasculature surrounding growth plates of high-fat diet mice and increased uptake when vascular levels peaked. High-fat diet growth plates had more activated IGF-I receptors and fewer inhibitory binding proteins, suggesting increased IGF-I bioavailability in growth plates. These results, which parallel pediatric growth patterns, highlight the fundamental role of diet in the earliest stages of developing obesity-related skeletal complications and validate the utility of the model for future studies aimed at determining mechanisms of diet-enhanced bone lengthening.NEW & NOTEWORTHY This paper validates a mouse model of linear growth acceleration in juvenile obesity. We demonstrate that high-fat diet induces rapid increases in bone elongation rate that precede excess weight gain and parallel pediatric growth. By imaging IGF-I delivery to growth plates in vivo, we reveal novel diet-induced changes in IGF-I uptake and activity. These results are important for understanding the sequelae of musculoskeletal complications that accompany advanced bone age and obesity in children.

Immunomodulatory Effects of Green Tea Polyphenols

Green tea and its bioactive components, especially polyphenols, possess many health-promoting and disease-preventing benefits, especially anti-inflammatory, antioxidant, anticancer, and metabolic modulation effects with multi-target modes of action. However, the effect of tea polyphenols on immune function has not been well studied. Moreover, the underlying cellular and molecular mechanisms mediating immunoregulation are not well understood. This review summarizes the recent studies on the immune-potentiating effects and corresponding mechanisms of tea polyphenols, especially the main components of (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG). In addition, the benefits towards immune-related diseases, such as autoimmune diseases, cutaneous-related immune diseases, and obesity-related immune diseases, have been discussed.

Antibody microarray analysis of serum inflammatory cytokines in patients with calcific aortic valve disease

Background

Calcific aortic valve disease (CAVD) is a slowly progressive pathologic process associated with significant morbidity and mortality, CAVD is the most common valve heart disease in the elderly and a leading cause of aortic valve stenosis. Multiple steps characterize the process: inflammation, cell apoptosis, lipid deposition, renin-angiotensin system activation, extracellular matrix remodeling, and bone formation. This paper focuses on detecting and analyzing the expression of serum inflammatory factors in CAVD by antibody microarray techniques.

Methods

In this study, a total of 258 patients were included at Tianjin Chest Hospital between January 2017 and December 2018, subjects were divided into three groups: control, coronary artery disease (CAD), and CAVD. Blood samples were collected, and adipokine/cytokine/chemokine serum profiles were measured by antibody arrays.

Results

These data suggest that B-Lymphocyte Chemoattractant (BLC), Interleukin (IL)-12p40, monokine inducible by γ interferon (MIG), and Macrophage inflammatory protein (MIP)-1delta were significantly increased in CAVD compared to control or CAD. Furthermore, Real-time quantified PCR, Western blot assay, and Flow cytometer detection showed that these four cytokines/chemokines were from peripheral blood mononuclear cells.

Conclusions

These findings suggest that BLC, IL-12p40, MIG, and MIP-1delta can be used as a marker to assess CAVD, which could have significant clinical implications.

Tea polyphenols attenuate liver inflammation by modulating obesity-related genes and down-regulating COX-2 and iNOS expression in high fat-fed dogs

Background

Tea polyphenols (TPs) attenuate obesity related liver inflammation; however, the anti-obesity effects and anti-inflammatory mechanisms are not clearly understood. This study aimed to determine whether the anti-obesity and anti-inflammatory TPs mechanisms associated with cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression levels, and obesity-related gene response in dogs.

Results

Dogs fed TPs displayed significantly decreased (p < 0.01) mRNA expression of tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) compared to dogs that consumed high-fat diet (HFD) alone. TPs significantly (p < 0.01) inhibited COX-2 and iNOS expression level, and decreased liver fat content and degeneration.

Conclusion

These results suggested that TPs act as a therapeutic agent for obesity, liver inflammation, and fat degeneration via COX-2 and iNOS inhibition, with TNF-α, IL-1β, and IL-6 involvement.

The chemokine CXCL16 can rescue the defects in insulin signaling and sensitivity caused by palmitate in C2C12 myotubes

In obesity, macrophages infiltrate peripheral tissues and secrete pro-inflammatory cytokines that impact local insulin sensitivity. Lipopolysaccharide (LPS) and the saturated fatty acid (FA) palmitate polarise macrophages towards a pro-inflammatory phenotype in vitro and indirectly cause insulin resistance (IR) in myotubes. In contrast, unsaturated FAs confer an anti-inflammatory phenotype and counteract the actions of palmitate. To explore paracrine mechanisms of interest, J774 macrophages were exposed to palmitate ± palmitoleate or control medium and the conditioned media generated were screened using a cytokine array. Of the 62 cytokines examined, 8 were significantly differentially expressed following FA treatments. Notably, CXCL16 secretion was downregulated by palmitate. In follow-up experiments using ELISAs, this downregulation was confirmed and reversed by simultaneous addition of palmitoleate or oleate, while LPS also diminished CXCL16 secretion. To dissect potential effects of CXCL16, C2C12 myotubes were treated with palmitate to induce IR, recombinant soluble CXCL16 (sCXCL16), combined treatment, or control medium. Palmitate caused the expected reduction of insulin-stimulated Akt activation and glycogen synthesis, whereas simultaneous treatment with sCXCL16 attenuated these effects. These data indicate a putative role for CXCL16 in preservation of Akt activation and insulin signaling in the context of chronic low-grade inflammation in skeletal muscle.

Consumption of a high energy density diet triggers microbiota dysbiosis, hepatic lipidosis, and microglia activation in the nucleus of the solitary tract in rats

Introduction

Obesity is a multifactorial chronic inflammatory disease. Consumption of high energy density (HED) diets is associated with hyperphagia, increased body weight and body fat accumulation, and obesity. Our lab has previously shown that short-term (4 weeks) consumption of a HED diet triggers gut microbiota dysbiosis, gut inflammation, and reorganization of the gut-brain vagal communication.

Objetives

The aim of this study was to investigate the effect of long-term (6 months) consumption of HED diet on body composition, gut microbiome, hepatocellular lipidosis, microglia activation in the nucleus of the solitary tract, and systemic inflammation.

Methods

Male Sprague–Dawley rats were fed a low energy density (LED) diet for 2 weeks and then switched to a HED diet for 26 weeks. Twenty-four-hour food intake, body weight, and body composition were measured twice a week. Blood serum and fecal samples were collected at baseline, 1, 4, 8, and 26 weeks after introduction of the HED diet. Serum samples were used to measure insulin, leptin, and inflammatory cytokines using Enzyme-linked Immunosorbent Assay. Fecal samples were assessed for 16 S rRNA genome sequencing.

Results

HED diet induced microbiota dysbiosis within a week of introducing the diet. In addition, there was significant microglia activation in the intermediate NTS and marked hepatic lipidosis after 4 weeks of HED diet. We further observed changes in the serum cytokine profile after 26 weeks of HED feeding.

Conclusions

These data suggest that microbiota dysbiosis is the first response of the organism to HED diets, followed by increased liver fat accumulation, microglia activation in the brain, and circulating levels of inflammatory markers. To our knowledge, this is the first study to present longitudinal and cross-sectional results on effect of long-term consumption of HED diets on all these parameters in a single cohort of animals.

Lansoprazole enhances the antidiabetic effect of dapagliflozin in fortified diet-fed streptozotocin-treated diabetic rats

Dapagliflozin (DAPA) is used for treating type 2 diabetes, whereas lansoprazole (LPZ) is used as a traditional antiulcer drug. The present study investigated the possible antidiabetic effects of LPZ on fortified diet-fed streptozotocin (FDF/STZ)-induced insulin-resistant diabetic rats. On the basis of the current results, it can be concluded that LPZ could be used as an add-on drug along with the conventional treatment for T2D as it showed beneficial effects in the current experimental model of insulin resistance.

Prostaglandin E2-Mediated Impairment of Innate Immune Response to A(H1N1)pdm09 Infection in Diet-Induced Obese Mice Could Be Restored by Paracetamol

BACKGROUND

Obesity is associated with increased severity of influenza infection. However, the underlying mechanism is largely unknown.

METHODS

We employed a mouse model with diet-induced obesity (DIO) to study the innate immune responses induced by influenza virus.

RESULTS

The lungs of DIO mice were heavily affected by obesity-associated chronic systemic inflammation with a significant increase in inflammatory cytokines/chemokines. Concurrently, lipid immune mediator prostaglandin E2 (PGE2) was also significantly elevated in DIO mice. However, the DIO mice mounted a blunted and delayed upregulation of mRNA and protein concentrations of interferon-β and inflammatory cytokines/chemokines upon A(H1N1)pdm09 virus (H1N1/415742Md) challenge compared with those of lean mice. PGE2 concentrations were significantly higher in the lungs of DIO mice compared to that of lean mice postchallenge. Treatment with paracetamol in challenged DIO mice significantly enhanced the expression of interferon-α/β and cytokine genes at days 1 and 3 postinfection compared with that of untreated DIO mice. Furthermore, paracetamol treatment alone started 3 days before virus challenge and continued until 6 days postchallenge ameliorated the severity of a lethal H1N1/415742Md infection in DIO mice with improved survival.

CONCLUSIONS

Impaired innate response to influenza in DIO mice is associated with elevated PGE2, which could be restored to some degree by paracetamol treatment.

Anti-obesity effects of dichloromethane leaf extract of Gnidia glauca in high fat diet-induced obese rats

BACKGROUND

Obesity is a chronic metabolic disorder characterized by increased adipose tissue mass due to positive energy balance. Prescription of anti-obesity drugs can be useful adjuncts to diet and exercise for obese patients who have failed to achieve weight loss. However, these drugs are ineffective and are associated with adverse effects. In recent times, medicinal plants have drawn a sharp focus owing to their biocompatibility and effectiveness. Attempts to determine the therapeutic effects and identification of bio-active principles from herbal prescriptions have become the prime focus in the validation of their folkloric usage and in drug discovery programs. Therefore, the present study aimed to determine the anti-obesity effects of Dichloromethane leaf extract of Gnidia glauca in high-fat-diet-induced obese rats.

METHODS

Obesity was induced experimentally in white albino Wistar rats by feeding them with prepared high-fat-diet and water ad libitum for a period of 12 weeks. The in-vivo anti-obesity effects were determined by oral administration of Gnidia glauca at dosage levels of 200, 250 and 300 mg/kg body weight from the 6th to 12th week of study. Phytochemical analysis of Gnidia glauca was conducted using gas chromatography linked to mass spectrophotometer.

RESULTS

The results indicated that Gnidia glauca exhibited potent anti-obesity effects. It significantly reduced the body weight, organ weights, organo-somatic indices, anthropometric indices, the total fat content, adiposity index, atherogenic index as well as various lipid profiles. It also decreased the total feed intake. However, it significantly increased levels of high-density lipoproteins and rectal body temperature of rats. Quantitative phytochemical analysis also revealed the presence of various phytocompounds that have shown to be associated with anti-obesity effects.

CONCLUSION

The anti-obesity effects of Gnidia glauca maybe attributed to the phytochemicals present. The present study, therefore, scientifically validates the traditional use of Gnidia glauca as a potential candidate for the synthesis of new effective anti-obesity supplement.

Obesity and cancer: A mechanistic overview of metabolic changes in obesity that impact genetic instability

Obesity, defined as a state of positive energy balance with a body mass index exceeding 30 kg/m2 in adults and 95th percentile in children, is an increasing global concern. Approximately one-third of the world's population is overweight or obese, and in the United States alone, obesity affects one in six children. Meta-analysis studies suggest that obesity increases the likelihood of developing several types of cancer, and with poorer outcomes, especially in children. The contribution of obesity to cancer risk requires a better understanding of the association between obesity-induced metabolic changes and its impact on genomic instability, which is a major driving force of tumorigenesis. In this review, we discuss how molecular changes during adipose tissue dysregulation can result in oxidative stress and subsequent DNA damage. This represents one of the many critical steps connecting obesity and cancer since oxidative DNA lesions can result in cancer-associated genetic instability. In addition, the by-products of the oxidative degradation of lipids (e.g., malondialdehyde, 4-hydroxynonenal, and acrolein), and gut microbiota-mediated secondary bile acid metabolites (e.g., deoxycholic acid and lithocholic acid), can function as genotoxic agents and tumor promoters. We also discuss how obesity can impact DNA repair efficiency, potentially contributing to cancer initiation and progression. Finally, we outline obesity-related epigenetic changes and identify the gaps in knowledge to be addressed for the development of better therapeutic strategies for the prevention and treatment of obesity-related cancers.

Cutting Edge: Elevated Leptin during Diet-Induced Obesity Reduces the Efficacy of Tumor Immunotherapy

Various malignancies are reproducibly cured in mouse models, but most cancer immunotherapies show objective responses in a fraction of treated patients. One reason for this disconnect may be the use of young, lean mice lacking immune-altering comorbidities present in cancer patients. Although many cancer patients are overweight or obese, the effect of obesity on antitumor immunity is understudied in preclinical tumor models. We examined the effect of obesity on two immunotherapeutic models: systemic anti-CTLA-4 mAb and intratumoral delivery of a TRAIL-encoding adenovirus plus CpG. Both therapies were effective in lean mice, but neither provided a survival benefit to diet-induced obese BALB/c mice. Interestingly, tumor-bearing leptin-deficient (ob/ob) obese BALB/c mice did respond to treatment. Moreover, reducing systemic leptin with soluble leptin receptor:Fc restored the antitumor response in diet-induced obese mice. These data demonstrate the potential of targeting leptin to improve tumor immunotherapy when immune-modulating comorbidities are present.

Time-restricted feeding mitigates high-fat diet-enhanced mammary tumorigenesis in MMTV-PyMT mice

Erratic eating behavior disrupts the daily feeding and fasting pattern and leads to metabolic dysfunction and chronic diseases including cancer. In the present study, we tested the hypothesis that time-restricted feeding of a high-fat diet (HFD) to the dark phase does not enhance mammary tumorigenesis in MMTV-PyMT mice. Female mice were assigned to 3 groups and fed the standard AIN93G diet or an HFD with or without dark phase restricted feeding (12 hours). The duration of restricted feeding was 8 weeks. The HFD group had 24% more body fat mass than the AIN93G group; the body fat mass of the restricted group remained similar to that of the AIN93G group. Energy intake of the restricted group was similar to that of the HFD and AIN93G groups. The median mammary tumor latency was 5.8, 7.0, and 6.4 weeks for the AIN93G, HFD, and restricted groups, respectively. Mammary tumor progression was 241% higher in the HFD group than that in the AIN93G group; there was no significant difference in tumor progression between the restricted and AIN93G groups. Plasma concentrations of leptin, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, angiopoietin-2, vascular endothelial growth factor, and hepatocyte growth factor were significantly higher in the HFD group than those in the control group; these measurements were similar between the restricted and control groups. In conclusion, feeding restricted to the dark phase mitigates the HFD-enhanced mammary tumorigenesis; this may be related to the lower body adiposity and associated inflammatory and angiogenic signals.

Dietary energy restriction reduces high-fat diet-enhanced metastasis of Lewis lung carcinoma in mice

The objective of this study was to determine whether a reduction in energy intake ameliorated the high-fat diet-enhanced spontaneous metastasis of Lewis lung carcinoma in mice. Male C57BL/6 mice were fed the AIN93G diet, a high-fat diet or a high-fat diet with a 5% restriction of the intake. Energy restriction reduced body adiposity and body weight, but maintained growth similar to mice fed the AIN93G diet. The high-fat diet significantly increased the number and size (cross-sectional area and volume) of metastases formed in lungs. Restricted feeding reduced the number of metastases by 23%, metastatic cross-sectional area by 32% and volume by 45% compared to the high-fat diet. The high-fat diet elevated plasma concentrations of proinflammatory cytokines (monocyte chemotactic protein-1, plasminogen activator inhibitor-1, leptin), angiogenic factors (vascular endothelial growth factor, tissue inhibitor of metalloproteinase-1) and insulin. Restricted feeding significantly reduced the high-fat diet-induced elevations in plasma concentrations of proinflammatory cytokines, angiogenic factors and insulin. These results demonstrated that a reduction in diet intake by 5% reduced high-fat diet-enhanced metastasis, which may be associated with the mitigation of adiposity and down-regulation of cancer-promoting proinflammatory cytokines and angiogenic factors.

One-Week Exposure to a Free-Choice High-Fat High-Sugar Diet Does Not Interfere With the Lipopolysaccharide-Induced Acute Phase Response in the Hypothalamus of Male Rats

Obesity has been associated with increased susceptibility to infection in humans and rodents. Obesity is also associated with low-grade hypothalamic inflammation that depends not only on body weight but also on diet. In the present study, we investigated if the bacterial endotoxin [lipopolysaccharide (LPS)]-induced acute phase response is aggravated in rats on a 1-week free-choice high-fat high-sugar (fcHFHS) diet and explained by diet-induced hypothalamic inflammation. Male Wistar rats were on an fcHFHS diet or chow for 1 week and afterwards intraperitoneally injected with LPS or saline. Hypothalamic inflammatory intermediates and plasma cytokines were measured after LPS. Both LPS and the fcHFHS diet altered hypothalamic Nfkbia mRNA and nuclear factor of kappa light polypeptide gene enhancer in B cells inhibitor alpha (NFKBIA) protein levels, whereas Il1β, Il6, and Tnfα mRNA expression was solely induced upon LPS. We observed an interaction in hypothalamic Nfkbia and suppressor of cytokine signaling (SOCS) 3 mRNA upon LPS; both were higher in rats on a fcHFHS diet compared with chow animals. Despite this, plasma cytokine levels between fcHFHS diet-fed and chow-fed rats were similar after LPS administration. Consuming a fcHFHS diet but not LPS injections increased hypothalamic Atf4 (a cellular stress marker) mRNA expression, whereas Tlr4 mRNA was decreased only upon LPS. Our study does not support a role for diet-induced mild hypothalamic inflammation in the increased susceptibility to infection despite altered Nfkbia and Socs3 mRNA expression after the diet. Additional factors, related to increased fat mass, might be involved.

Monocyte chemotactic protein-1 deficiency reduces spontaneous metastasis of Lewis lung carcinoma in mice fed a high-fat diet

Adipose-produced pro-inflammatory cytokines contribute to obesity and cancer. This 2×2 experiment was designed to investigate effects of monocyte chemotactic protein-1 (MCP-1) deficiency on pulmonary metastasis of Lewis lung carcinoma (LLC) in MCP-1 deficient and wild-type mice fed a modified AIN93G diet containing 16% and 45% of energy from corn oil, respectively. The high-fat diet significantly increased the number and size (cross-sectional area and volume) of lung metastases compared to the AIN93G control diet. Deficiency in MCP-1 reduced lung metastases by 37% in high-fat diet-fed mice; it reduced metastatic cross-sectional area by 46% and volume by 69% compared to wild-type mice. Adipose and plasma concentrations of MCP-1 were significantly higher in high-fat diet-fed wild-type mice than in their AIN93G-fed counterparts; they were not detectable in MCP-1 deficient mice regardless of diet. Plasma concentrations of plasminogen activator inhibitor-1, tumor necrosis factor-α, vascular endothelial growth factor and tissue inhibitor of metalloproteinase-1 were significantly higher in MCP-1 deficient mice compared to wild-type mice. We conclude that adipose-produced MCP-1 contributes to high-fat diet-enhanced metastasis. While MCP-1 deficiency reduces metastasis, the elevation of pro-inflammatory cytokines and angiogenic factors in the absence of MCP-1 may support the metastatic development and growth of LLC in MCP-1 deficient mice.

Depot-specific inflammation with decreased expression of ATM2 in white adipose tissues induced by high-margarine/lard intake

A high-fat diet has been recognized as an important risk factor of obesity, with variable impacts of different fatty acid compositions on the physiological process. To understand the effects of a high-margarine/lard diet, which is a major source of trans fatty acids (TFAs)/ saturated fatty acids (SFAs), elaidic acid as a biomarker of margarine intake was used to screen affected adipokines on mature human adipocytes in vitro. Weaned male Wistar rats were fed a high-fat diet enriched with margarine/lard to generate obesity-prone (OP) and obesity-resistant (OR) models, which were then used to explore the inflammatory responses of depot-specific white adipose tissue. Adiposity, glucose and lipid metabolism parameters and macrophage cell markers were also compared in vivo. In the subcutaneous depot, a high-margarine diet induced elevated IL-6, MCP-1 and XCL1 expression levels in both M-OP and M-OR groups. High-lard diet-fed rats displayed higher protein expression levels of MCP-1 and XCL1 compared with the control group. In the epididymal depot, significantly elevated IL-6 production was observed in M-OP rats, and high-lard diet-fed rats displayed elevated IL-6 and decreased XCL1 expression. In the retroperitoneal depot, a high-margarine diet caused higher IL-6 and MCP-1 expression levels, a high-lard diet caused elevated IL-6 expression in L-OP/L-OR rats, and elevated XCL1 expression was observed only in L-OP rats. In general, CD206 mRNA levels were notably down-regulated by high-fat diet feeding in the above-mentioned depots. CD11c mRNA levels were slightly upregulated in the subcutaneous depot of OP rats fed a high-margarine/lard diet. In the epidydimal depot, higher expression levels of F4/80 and CD206 mRNA were observed only in high-margarine diet-fed OP rats. These results suggest that depot-specific inflammation with decreased expression of adipose tissue anti-inflammatory M2-type (ATM2) macrophages could be induced by high-margarine/lard intake.

Association of Plasma SDF-1 with Bone Mineral Density, Body Composition, and Hip Fractures in Older Adults: The Cardiovascular Health Study

Aging is associated with an increase in circulating inflammatory factors. One, the cytokine stromal cell-derived factor 1 (SDF-1 or CXCL12), is critical to stem cell mobilization, migration, and homing as well as to bone marrow stem cell (BMSC), osteoblast, and osteoclast function. SDF-1 has pleiotropic roles in bone formation and BMSC differentiation into osteoblasts/osteocytes, and in osteoprogenitor cell survival. The objective of this study was to examine the association of plasma SDF-1 in participants in the cardiovascular health study (CHS) with bone mineral density (BMD), body composition, and incident hip fractures. In 1536 CHS participants, SDF-1 plasma levels were significantly associated with increasing age (p < 0.01) and male gender (p = 0.04), but not with race (p = 0.63). In multivariable-adjusted models, higher SDF-1 levels were associated with lower total hip BMD (p = 0.02). However, there was no significant association of SDF-1 with hip fractures (p = 0.53). In summary, circulating plasma levels of SDF-1 are associated with increasing age and independently associated with lower total hip BMD in both men and women. These findings suggest that SDF-1 levels are linked to bone homeostasis.

Obesity-associated cancer risk: the role of intestinal microbiota in the etiology of the host proinflammatory state

Obesity increases the risks of many cancers. One important mechanism behind this association is the obesity-associated proinflammatory state. Although the composition of the intestinal microbiome undoubtedly can contribute to the proinflammatory state, perhaps the most important aspect of host-microbiome interactions is host exposure to components of intestinal bacteria that stimulate inflammatory reactions. Systemic exposures to intestinal bacteria can be modulated by dietary factors through altering both the composition of the intestinal microbiota and the absorption of bacterial products from the intestinal lumen. In particular, high-fat and high-energy diets have been shown to facilitate absorption of bacterial lipopolysaccharide (LPS) from intestinal bacteria. Biomarkers of bacterial exposures that have been measured in blood include LPS-binding protein, sCD14, fatty acids characteristic of intestinal bacteria, and immunoglobulins specific for bacterial LPS and flagellin. The optimal strategies to reduce these proinflammatory exposures, whether by altering diet composition, avoiding a positive energy balance, or reducing adipose stores, likely differ in each individual. Biomarkers that assess systemic bacterial exposures therefore should be useful to (1) optimize and personalize preventive approaches for individuals and groups with specific characteristics and to (2) gain insight into the possible mechanisms involved with different preventive approaches.

Inside out: Bone marrow adipose tissue as a source of circulating adiponectin

The adipocyte-derived hormone adiponectin mediates beneficial cardiometabolic effects, and hypoadiponectinemia is a biomarker for increased metabolic and cardiovascular risk. Indeed, circulating adiponectin decreases in obesity and insulin-resistance, likely because of impaired production from white adipose tissue (WAT). Conversely, lean states such as caloric restriction (CR) are characterized by hyperadiponectinemia, even without increased adiponectin production from WAT. The reasons underlying this paradox have remained elusive, but our recent research suggests that CR-associated hyperadiponectinemia derives from an unexpected source: bone marrow adipose tissue (MAT). Herein, we elaborate on this surprising discovery, including further discussion of potential mechanisms influencing adiponectin production from MAT; additional evidence both for and against our conclusions; and observations suggesting that the relationship between MAT and adiponectin might extend beyond CR. While many questions remain, the burgeoning study of MAT promises to reveal further key insights into MAT biology, both as a source of adiponectin and beyond.

Adapting Cancer Immunotherapy Models for the Real World

Early experiments in mice predicted the success of checkpoint blockade immunotherapy in cancer patients. However, these same animal studies failed to accurately predict many of the limitations and toxicities of treatment. One of the likely reasons for this discrepancy is the nearly universal use of young healthy mice, which stand in stark contrast to diverse patient populations varying in age, weight, diet, and hygiene. Because these variables impact immunity and metabolism, they also influence outcomes during immunotherapy and should be incorporated into the study design of preclinical experiments. Here, we discuss recent findings that highlight how efficacy and toxicity of cancer immunotherapy are affected by patient variation, and how distinct host environments can be better modeled in animal studies.

Relationship of the Chemokine, CXCL12, to Effects of Dietary Fat on Feeding-Related Behaviors and Hypothalamic Neuropeptide Systems

The intake of a high fat diet (HFD), in addition to stimulating orexigenic neuropeptides in the hypothalamus while promoting overeating and reducing locomotor behavior, is known to increase inflammatory mediators that modulate neuronal systems in the brain. To understand the involvement of chemokines in the effects of a HFD, we examined in rats whether HFD intake affects a specific chemokine, CXCL12, and its receptors, CXCR4 and CXCR7, in the hypothalamus together with the neuropeptides and whether CXCL12 itself acts similarly to a HFD in stimulating the neuropeptides and altering ingestion and locomotor behavior. Compared to low-fat chow, a HFD for 5 days significantly increased the expression of CXCL12 and its receptors, in both the paraventricular nucleus (PVN) where the neuropeptides enkephalin (ENK) and galanin were also stimulated and the perifornical lateral hypothalamus (PFLH) where orexin (OX) and melanin-concentrating hormone (MCH) were increased. In contrast, the HFD had no impact on expression of CXCL12 or its receptors in the arcuate nucleus (ARC) where the carbohydrate-related peptide, neuropeptide Y (NPY), was suppressed. Analysis of protein levels revealed a similar stimulatory effect of a HFD on CXCL12 levels in the PVN and PFLH, as well as in blood, and an increase in the number of CXCR4-positive cells in the PVN. In the ARC, in contrast, levels of CXCL12 and number of CXCR4-positive cells were too low to measure. When centrally administered, CXCL12 was found to have similar effects to a HFD. Injection of CXCL12 into the third cerebral ventricle immediately anterior to the hypothalamus significantly stimulated the ingestion of a HFD, reduced novelty-induced locomotor activity, and increased expression of ENK in the PVN where the CXCR4 receptors were dense. It had no impact, however, on NPY in the ARC or on OX and MCH in the PFLH where the CXCR4 receptors were not detected. These results, showing CXCL12 in the hypothalamus to be stimulated by a HFD and to mimic the effects of the HFD where its receptors are located, suggest that this chemokine system may have a role in mediating both the neuronal and behavioral effects induced by a fat-rich diet.

Expansion of Bone Marrow Adipose Tissue During Caloric Restriction Is Associated With Increased Circulating Glucocorticoids and Not With Hypoleptinemia

Bone marrow adipose tissue (MAT) accounts for up to 70% of bone marrow volume in healthy adults and increases further in clinical conditions of altered skeletal or metabolic function. Perhaps most strikingly, and in stark contrast to white adipose tissue, MAT has been found to increase during caloric restriction (CR) in humans and many other species. Hypoleptinemia may drive MAT expansion during CR but this has not been demonstrated conclusively. Indeed, MAT formation and function are poorly understood; hence, the physiological and pathological roles of MAT remain elusive. We recently revealed that MAT contributes to hyperadiponectinemia and systemic adaptations to CR. To further these observations, we have now performed CR studies in rabbits to determine whether CR affects adiponectin production by MAT. Moderate or extensive CR decreased bone mass, white adipose tissue mass, and circulating leptin but, surprisingly, did not cause hyperadiponectinemia or MAT expansion. Although this unexpected finding limited our subsequent MAT characterization, it demonstrates that during CR, bone loss can occur independently of MAT expansion; increased MAT may be required for hyperadiponectinemia; and hypoleptinemia is not sufficient for MAT expansion. We further investigated this relationship in mice. In females, CR increased MAT without decreasing circulating leptin, suggesting that hypoleptinemia is also not necessary for MAT expansion. Finally, circulating glucocorticoids increased during CR in mice but not rabbits, suggesting that glucocorticoids might drive MAT expansion during CR. These observations provide insights into the causes and consequences of CR-associated MAT expansion, knowledge with potential relevance to health and disease.

Weight-reduction through a low-fat diet causes differential expression of circulating microRNAs in obese C57BL/6 mice

BACKGROUND

To examine the circulating microRNA (miRNA) expression profile in a mouse model of diet-induced obesity (DIO) with subsequent weight reduction achieved via low-fat diet (LFD) feeding.

RESULTS

Eighteen C57BL/6NCrl male mice were divided into three subgroups: (1) control, mice were fed a standard AIN-76A (fat: 11.5 kcal %) diet for 12 weeks; (2) DIO, mice were fed a 58 kcal % high-fat diet (HFD) for 12 weeks; and (3) DIO + LFD, mice were fed a HFD for 8 weeks to induce obesity and then switched to a 10.5 kcal % LFD for 4 weeks. A switch to LFD feeding led to decreases in body weight, adiposity, and blood glucose levels in DIO mice. Microarray analysis of miRNA using The Mouse & Rat miRNA OneArray® v4 system revealed significant alterations in the expression of miRNAs in DIO and DIO + LFD mice. Notably, 23 circulating miRNAs (mmu-miR-16, mmu-let-7i, mmu-miR-26a, mmu-miR-17, mmu-miR-107, mmu-miR-195, mmu-miR-20a, mmu-miR-25, mmu-miR-15b, mmu-miR-15a, mmu-let-7b, mmu-let-7a, mmu-let-7c, mmu-miR-103, mmu-let-7f, mmu-miR-106a, mmu-miR-106b, mmu-miR-93, mmu-miR-23b, mmu-miR-21, mmu-miR-30b, mmu-miR-221, and mmu-miR-19b) were significantly downregulated in DIO mice but upregulated in DIO + LFD mice. Target prediction and function annotation of associated genes revealed that these genes were predominantly involved in metabolic, insulin signaling, and adipocytokine signaling pathways that directly link the pathophysiological changes associated with obesity and weight reduction.

CONCLUSIONS

These results imply that obesity-related reductions in the expression of circulating miRNAs could be reversed through changes in metabolism associated with weight reduction achieved through LFD feeding.

Caloric restriction and the adipokine leptin alter the SDF-1 signaling axis in bone marrow and in bone marrow derived mesenchymal stem cells

Growing evidence suggests that the chemokine stromal cell-derived factor-1 (SDF-1) is essential in regulating bone marrow (BM) derived mesenchymal stromal/stem cell (BMSC) survival, and differentiation to either a pro-osteogenic or pro-adipogenic fate. This study investigates the effects of caloric restriction (CR) and leptin on the SDF-1/CXCR4 axis in bone and BM tissues in the context of age-associated bone loss. For in vivo studies, we collected bone, BM cells and BM interstitial fluid from 12 and 20 month-old C57Bl6 mice fed ad-libitum (AL), and 20-month-old mice on long-term CR with, or without, intraperitoneal injection of leptin for 10 days (10 mg/kg). To mimic conditions of CR in vitro, 18 month murine BMSCs were treated with (1) control (Ctrl): normal proliferation medium, (2) nutrient restriction (NR): low glucose, low serum medium, or (3) NR + leptin: NR medium + 100 ng/ml leptin for 6-48 h. In BMSCs both protein and mRNA expression of SDF-1 and CXCR4 were increased by CR and CR + leptin. In contrast, the alternate SDF-1 receptor CXCR7 was decreased, suggesting a nutrient signaling mediated change in SDF-1 axis signaling in BMSCs. However, in bone SDF-1, CXCR4 and 7 gene expression increase with age and this is reversed with CR, while addition of leptin returns this to the "aged" level. Histologically bone formation was lower in the calorically restricted mice and BM adipogenesis increased, both effects were reversed with the 10 day leptin treatment. This suggests that in bone CR and leptin alter the nutrient signaling pathways in different ways to affect the local action of the osteogenic cytokine SDF-1. Studies focusing on the molecular interaction between nutrient signaling by CR, leptin and SDF-1 axis may help to address age-related musculoskeletal changes.

Using diet-induced obesity to understand a metabolic subtype of osteoarthritis in rats

Osteoarthritis (OA) in obese individuals is often attributed to joint loading. However, a subtype of OA, Metabolic OA, may be due to obesity-related intrinsic factors but remains to be evaluated experimentally against a known OA progression model.

OBJECTIVE

To evaluate if obesity contributes to OA onset using a high fat/high sucrose diet-induced obesity (DIO) model with anterior cruciate ligament-transected rats (ACL-X).

METHODS

Sprague Dawley rats (n = 33) consumed high fat/high sucrose or chow diets for 12 weeks, were randomized to one of three groups: a unilateral ACL-X group, sham surgery group, or naïve non-surgical group. These animals were followed for an additional 16 weeks. At sacrifice, body composition, knee joint Modified Mankin scores, and 27 serum and synovial fluid cytokines and adipokines were measured.

RESULTS

Experimental limbs of obese ACL-X, obese Sham, and lean ACL-X animals had similar Modified Mankin scores that were greater than those obtained from lean Sham and naïve animals. Obese contralateral limbs had similar OA damage as ACL-X and Sham limbs of obese and ACL-X limbs of lean animals. Obese contralateral limb Modified Mankin scores had a strong correlation (r = 0.75, P < 0.001) with body fat percentage. Serum leptin and synovial fluid IP10/CXCL10 best described Modified Mankin scores in contralateral limbs of obese animals.

CONCLUSIONS

Mechanical factors produced OA damage in experimental limbs, as expected. Interestingly, OA damage in obese contralateral limbs was similar to mechanically perturbed limbs, suggesting that obesity may induce OA in a non-mechanical manner.

Diet, behavior and immunity across the lifespan

It is increasingly appreciated that perinatal events can set an organism on a life-long trajectory for either health or disease, resilience or risk. One early life variable that has proven critical for optimal development is the nutritional environment in which the organism develops. Extensive research has documented the effects of both undernutrition and overnutrition, with strong links evident for an increased risk for obesity and metabolic disorders, as well as adverse mental health outcomes. Recent work has highlighted a critical role of the immune system, in linking diet with long term health and behavioral outcomes. The present review will summarize the recent literature regarding the interactions of diet, immunity, and behavior.

CpG-mediated modulation of MDSC contributes to the efficacy of Ad5-TRAIL therapy against renal cell carcinoma

Tumor progression occurs through the modulation of a number of physiological parameters, including the development of immunosuppressive mechanisms to prevent immune detection and response. Among these immune evasion mechanisms, the mobilization of myeloid-derived suppressor cells (MDSC) is a major contributor to the suppression of antitumor T-cell immunity. Patients with renal cell carcinoma (RCC) show increased MDSC, and methods are being explored clinically to reduce the prevalence of MDSC and/or inhibit their function. In the present study, we investigated the relationship between MDSC and the therapeutic potential of a TRAIL-encoding recombinant adenovirus (Ad5-TRAIL) in combination with CpG-containing oligodeoxynucleotides (Ad5-TRAIL/CpG) in an orthotopic mouse model of RCC. This immunotherapy effectively clears renal (Renca) tumors and enhances survival, despite the presence of a high frequency of MDSC in the spleens and primary tumor-bearing kidneys at the time of treatment. Subsequent analyses revealed that the CpG component of the immunotherapy was responsible for decreasing the frequency of MDSC in Renca-bearing mice; further, treatment with CpG modulated the phenotype and function of MDSC that remained after immunotherapy and correlated with an increased T-cell response. Interestingly, the CpG-dependent alterations in MDSC frequency and function did not occur in tumor-bearing mice complicated with diet-induced obesity. Collectively, these data suggest that in addition to its adjuvant properties, CpG also enhances antitumor responses by altering the number and function of MDSC.

Obesity promotes aerobic glycolysis in prostate cancer cells

Obesity is the leading preventable comorbidity associated with increased prostate cancer-related recurrence and mortality. Epidemiological and clinical studies indicate that a body mass index >30 is associated with increased oxidative DNA damage within the prostate gland and increased prostate cancer-related mortality. Here we provide evidence that obesity promotes worse clinical outcome through induction of metabolic abnormalities known to promote genotoxic stress. We have previously reported that blood serum derived from obese mice may enhance the proliferative and invasive potential of human prostate cancer cell lines ex vivo. Here we show that a 1-h exposure of LNCaP or PacMetUT1 prostate cancer cell lines and nonmalignant RWPE-1 prostate epithelial cells to 2% serum from obese mice induces markers of aerobic glycolysis relative to those exposed to serum from nonobese mice. This metabolic change was correlated with accumulation of reactive oxygen species (ROS) and increased frequency of DNA double-strand breaks. Interestingly, N-tert-Butylhydroxylamine, an antioxidant, significantly suppressed markers of aerobic glycolysis in the cells exposed to the blood serum of obese mice, suggesting that ROS contributes to a metabolic shift toward aerobic glycolysis. Here we describe obesity-induced changes in key metabolic markers that impact prostate cancer cell progression and explore the role of antioxidants in ameliorating these effects.

Calorie restriction decreases murine and human pancreatic tumor cell growth, nuclear factor-κB activation, and inflammation-related gene expression in an insulin-like growth factor-1-dependent manner

Calorie restriction (CR) prevents obesity and has potent anticancer effects that may be mediated through its ability to reduce serum growth and inflammatory factors, particularly insulin-like growth factor (IGF)-1 and protumorigenic cytokines. IGF-1 is a nutrient-responsive growth factor that activates the inflammatory regulator nuclear factor (NF)-κB, which is linked to many types of cancers, including pancreatic cancer. We hypothesized that CR would inhibit pancreatic tumor growth through modulation of IGF-1-stimulated NF-κB activation and protumorigenic gene expression. To test this, 30 male C57BL/6 mice were randomized to either a control diet consumed ad libitum or a 30% CR diet administered in daily aliquots for 21 weeks, then were subcutaneously injected with syngeneic mouse pancreatic cancer cells (Panc02) and tumor growth was monitored for 5 weeks. Relative to controls, CR mice weighed less and had decreased serum IGF-1 levels and smaller tumors. Also, CR tumors demonstrated a 70% decrease in the expression of genes encoding the pro-inflammatory factors S100a9 and F4/80, and a 56% decrease in the macrophage chemoattractant, Ccl2. Similar CR effects on tumor growth and NF-κB-related gene expression were observed in a separate study of transplanted MiaPaCa-2 human pancreatic tumor cell growth in nude mice. In vitro analyses in Panc02 cells showed that IGF-1 treatment promoted NF-κB nuclear localization, increased DNA-binding of p65 and transcriptional activation, and increased expression of NF-κB downstream genes. Finally, the IGF-1-induced increase in expression of genes downstream of NF-κB (Ccdn1, Vegf, Birc5, and Ptgs2) was decreased significantly in the context of silenced p65. These findings suggest that the inhibitory effects of CR on Panc02 pancreatic tumor growth are associated with reduced IGF-1-dependent NF-κB activation.

Effects of interventions on adiponectin and adiponectin receptors

Adiponectin secreted from adipose tissue binds to two distinct adiponectin receptors (AdipoR1 and AdipoR2) identified and exerts its anti-diabetic effects in insulin-sensitive organs including liver, skeletal muscle and adipose tissue as well as amelioration of vascular dysfunction in the various vasculatures. A number of experimental and clinical observations have demonstrated that circulating levels of adiponectin are markedly reduced in obesity, type 2 diabetes, hypertension, and coronary artery disease. Therapeutic interventions which can improve the action of adiponectin including elevation of circulating adiponectin concentration or up-regulation and/or activation of its receptors, could provide better understanding of strategies to ameliorate metabolic disorders and vascular disease. The focus of the present review is to summarize accumulating evidence showing the role of interventions such as pharmacological agents, exercise, and calorie restriction in the expression of adiponectin and adiponectin receptors.

Effects of calorie restriction and diet-induced obesity on murine colon carcinogenesis, growth and inflammatory factors, and microRNA expression

Obesity is an established colon cancer risk factor, while preventing or reversing obesity via a calorie restriction (CR) diet regimen decreases colon cancer risk. Unfortunately, the biological mechanisms underlying these associations are poorly understood, hampering development of mechanism-based approaches for preventing obesity-related colon cancer. We tested the hypotheses that diet-induced obesity (DIO) would increase (and CR would decrease) colon tumorigenesis in the mouse azoxymethane (AOM) model. In addition, we established that changes in inflammatory cytokines, growth factors, and microRNAs are associated with these energy balance-colon cancer links, and thus represent mechanism-based targets for colon cancer prevention. Mice were injected with AOM once a week for 5 weeks and randomized to: 1) control diet; 2) 30% CR diet; or 3) DIO diet. Mice were euthanized at week 5 (n = 12/group), 10 (n = 12/group), and 20 (n = 20/group) after the last AOM injection. Colon tumors were counted, and cytokines, insulin-like growth factor 1 (IGF-1), IGF binding protein 3 (IGFBP-3), adipokines, proliferation, apoptosis, and expression of microRNAs (miRs) were measured. The DIO diet regimen induced an obese phenotype (∼36% body fat), while CR induced a lean phenotype (∼14% body fat); controls were intermediate (∼26% body fat). Relative to controls, DIO increased (and CR decreased) the number of colon tumors (p = 0.01), cytokines (p<0.001), IGF-1 (p = 0.01), and proliferation (p<0.001). DIO decreased (and CR increased) IGFBP-3 and apoptosis (p<0.001). miRs including mir-425, mir-196, mir-155, mir-150, mir-351, mir-16, let-7, mir34, and mir-138 were differentially expressed between the dietary groups. We conclude that the enhancing effects of DIO and suppressive effects of CR on colon carcinogenesis are associated with alterations in several biological pathways, including inflammation, IGF-1, and microRNAs.

Chemokine network during adipogenesis in 3T3-L1 cells: Differential response between growth and proinflammatory factor in preadipocytes vs. adipocytes

Obesity is recognized as a low-grade chronic inflammatory state which involves a chemokine network contributing to a variety of diseases. As a first step toward understanding the roles of the obesity-driven chemokine network, we used a 3T3-L1 cell differentiation model to identify the chemokine profiles elicited during adipogenesis and how this profile is modified by epidermal growth factor (EGF) and tumor necrosis factor-α (TNF) as a growth and proinflammatory factor, respectively. The chemokine network was monitored using PCR arrays and qRT-PCR while main signaling pathways of EGF and TNF were measured using immunoblotting. The dominant chemokines in preadipocytes were CCL5, CCL8, CXCL1, and CXCL16, and in adipocytes CCL6 and CXCL13. The following chemokines were found in both preadipocytes and adipocytes: CCL2, CCL7, CCL25, CCL27, CXCL5, CXCL12, and CX3CL1. Among chemokine receptors, CXCR7 was specific for preadipocytes and CXCR2 for adipocytes. These findings indicate the development of a CXCL12–CXCR7 axis in preadipocytes and a CXCL5–CXCR2 axis in adipocytes. In addition to induction of CCL2 and CCL7 in both preadipocytes and adipocytes, EGF enhanced specifically CXCL1 and CXCL5 in adipocytes, indicating the potentiation of CXCR2-mediated pathway in adipocytes. TNF induced CCL2, CCL7, and CXCL1 in preadipocytes but had no response in adipocytes. EGFR downstream activation was dominant in adipocytes whereas NFκB activation was dominant in preadipocytes. Taken together, the adipocyte-driven chemokine network in the 3T3-L1 cell differentiation model involves CXCR2-mediated signaling which appears more potentiated to growth factors like EGF than proinflammatory factors like TNF.

High-fat feeding rapidly induces obesity and lipid derangements in C57BL/6N mice

C57BL/6N (B6N) is becoming the standard background for genetic manipulation of the mouse genome. The B6N, whose genome is very closely related to the reference C57BL/6J genome, is versatile in a wide range of phenotyping and experimental settings and large repositories of B6N ES cells have been developed. Here, we present a series of studies showing the baseline characteristics of B6N fed a high-fat diet (HFD) for up to 12 weeks. We show that HFD-fed B6N mice show increased weight gain, fat mass, and hypercholesterolemia compared to control diet-fed mice. In addition, HFD-fed B6N mice display a rapid onset of lipid accumulation in the liver with both macro- and microvacuolation, which became more severe with increasing duration of HFD. Our results suggest that the B6N mouse strain is a versatile background for studying diet-induced metabolic syndrome and may also represent a model for early nonalcoholic fatty liver disease.

Insulin resistance and cancer: the role of insulin and IGFs

Insulin, IGF1, and IGF2 are the most studied insulin-like peptides (ILPs). These are evolutionary conserved factors well known as key regulators of energy metabolism and growth, with crucial roles in insulin resistance-related metabolic disorders such as obesity, diseases like type 2 diabetes mellitus, as well as associated immune deregulations. A growing body of evidence suggests that insulin and IGF1 receptors mediate their effects on regulating cell proliferation, differentiation, apoptosis, glucose transport, and energy metabolism by signaling downstream through insulin receptor substrate molecules and thus play a pivotal role in cell fate determination. Despite the emerging evidence from epidemiological studies on the possible relationship between insulin resistance and cancer, our understanding on the cellular and molecular mechanisms that might account for this relationship remains incompletely understood. The involvement of IGFs in carcinogenesis is attributed to their role in linking high energy intake, increased cell proliferation, and suppression of apoptosis to cancer risks, which has been proposed as the key mechanism bridging insulin resistance and cancer. The present review summarizes and discusses evidence highlighting recent advances in our understanding on the role of ILPs as the link between insulin resistance and cancer and between immune deregulation and cancer in obesity, as well as those areas where there remains a paucity of data. It is anticipated that issues discussed in this paper will also recover new therapeutic targets that can assist in diagnostic screening and novel approaches to controlling tumor development.

Adipose tissue attracts and protects acute lymphoblastic leukemia cells from chemotherapy

Obesity is associated with an increased risk of acute lymphoblastic leukemia (ALL) relapse. Using mouse and cell co-culture models, we investigated whether adipose tissue attracts ALL to a protective microenvironment. Syngeneically implanted ALL cells migrated into adipose tissue within ten days. In vitro, murine ALL cells migrated towards adipose tissue explants and 3T3-L1 adipocytes. Human and mouse ALL cells migrated toward adipocyte conditioned media, which was mediated by SDF-1α. In addition, adipose tissue explants protected ALL cells against daunorubicin and vincristine. Our findings suggest that ALL migration into adipose tissue could contribute to drug resistance and potentially relapse.

Distinctive genes determine different intramuscular fat and muscle fiber ratios of the longissimus dorsi muscles in Jinhua and landrace pigs

Meat quality is determined by properties such as carcass color, tenderness and drip loss. These properties are closely associated with meat composition, which includes the types of muscle fiber and content of intramuscular fat (IMF). Muscle fibers are the main contributors to meat mass, while IMF not only contributes to the sensory properties but also to the plethora of physical, chemical and technological properties of meat. However, little is known about the molecular mechanisms that determine meat composition in different pig breeds. In this report we show that Jinhua pigs, a Chinese breed, contains much higher levels of IMF than do Landrace pigs, a Danish breed. We analyzed global gene expression profiles in the longissimus dorsi muscles in Jinhua and Landrace breeds at the ages of 30, 90 and 150 days. Cross-comparison analysis revealed that genes that regulate fatty acid biosynthesis (e.g., fatty acid synthase and stearoyl-CoA desaturase) are expressed at higher levels in Jinhua pigs whereas those that regulate myogenesis (e.g., myogenic factor 6 and forkhead box O1) are expressed at higher levels in Landrace pigs. Among those genes which are highly expressed in Jinhua pigs at 90 days (d90), we identified a novel gene porcine FLJ36031 (pFLJ), which functions as a positive regulator of fat deposition in cultured intramuscular adipocytes. In summary, our data showed that the up-regulation of fatty acid biosynthesis regulatory genes such as pFLJ and myogenesis inhibitory genes such as myostatin in the longissimus dorsi muscles of Jinhua pigs could explain why this local breed produces meat with high levels of IMF.

A systematic review of the impact of weight loss on cancer incidence and mortality

Obesity is well recognized as a significant risk factor for certain cancers; however, a corresponding risk reduction with weight loss is not yet clearly defined. This review aims to examine the literature investigating the effect of all types of weight loss on cancer incidence and mortality, and to more clearly describe the relationship between these two factors. A literature search identified 34 publications reporting weight loss data in relation to cancer incidence or mortality. All except one were observational studies and the majority used self-reported weights and did not define intentionality of weight loss. 16/34 studies found a significant inverse association between weight loss and cancer incidence or mortality. The remainder returned null findings. The observed association was more consistently seen in studies that investigated the effect of intentional weight loss (5/6 studies) and the risk reduction was greatest for obesity-related cancers and in women. In conclusion, intentional weight loss does result in a decreased incidence of cancer, particularly female obesity-related cancers. However, there is a need for further evaluation of sustained intentional weight loss in the obese with less reliance on self-reported weight data and more focus on male populations.

Female mice are protected against high-fat diet induced metabolic syndrome and increase the regulatory T cell population in adipose tissue

Sex differences in obesity-induced complications such as type 2 diabetes have been reported. The aim of the study was to pinpoint the mechanisms resulting in different outcome of female and male mice on a high-fat diet (HFD). Mice fed control or HFD were monitored for weight, blood glucose, and insulin for 14 weeks. Circulating chemokines, islet endocrine function and blood flow, as well as adipose tissue populations of macrophages and regulatory T-lymphocytes (T_reg) were thereafter assessed. Despite similar weight (43.8±1.0 and 40.2±1.5 g, respectively), male but not female mice developed hyperinsulinemia on HFD as previously described (2.5±0.7 and 0.5±0.1 pmol/l, respectively) consistent with glucose intolerance. Male mice also exhibited hypertrophic islets with intact function in terms of insulin release and blood perfusion. Low-grade, systemic inflammation was absent in obese female but present in obese male mice (IL-6 and mKC, males: 77.4±17 and 1795±563; females: 14.6±4.9 and 240±22 pg/ml), and the population of inflammatory macrophages was increased in intra-abdominal adipose tissues of high-fat-fed male but not female mice. In contrast, the anti-inflammatory T_reg cell population increased in the adipose tissue of female mice in response to weight gain, while the number decreased in high-fat-fed male mice. In conclusion, female mice are protected against HFD-induced metabolic changes while maintaining an anti-inflammatory environment in the intra-abdominal adipose tissue with expanded T_reg cell population, whereas HFD-fed male mice develop adipose tissue inflammation, glucose intolerance, hyperinsulinemia, and islet hypertrophy.

Decreased systemic IGF-1 in response to calorie restriction modulates murine tumor cell growth, nuclear factor-κB activation, and inflammation-related gene expression

Calorie restriction (CR) prevents obesity and has potent anticancer effects associated with altered hormones and cytokines. We tested the hypothesis that CR inhibits MC38 mouse colon tumor cell growth through modulation of hormone-stimulated nuclear factor (NF)-κB activation and protumorigenic gene expression. Female C57BL/6 mice were randomized (n = 30/group) to receive control diet or 30% CR diet. At 20 wk, 15 mice/group were killed for body composition analysis. At 21 wk, serum was obtained for hormone analysis. At 22 wk, mice were injected with MC38 cells; tumor growth was monitored for 24 d. Gene expression in excised tumors and MC38 cells was analyzed using real-time RT-PCR. In vitro MC38 NF-κB activation (by p65 ELISA and immunofluorescence) were measured in response to varying IGF-1 concentrations (1-400 ng/mL). Relative to controls, CR mice had decreased tumor volume, body weight, body fat, serum IGF-1, serum leptin, and serum insulin, and increased serum adiponectin (P < 0.05, each). Tumors from CR mice, versus controls, had downregulated inflammation- and/or cancer-related gene expression, including interleukin (IL)-6, IL-1β, tumor necrosis factor-α, cyclooxygenase-2, chemokine (C-C motif) ligand-2, S100A9, and F4/80, and upregulated 15-hydroxyprostaglandin dehydrogenase expression. In MC38 cells in vitro, IGF-1 increased NF-κB activation and NF-κB downstream gene expression (P < 0.05, each). We conclude that CR, in association with reduced systemic IGF-1, modulates MC38 tumor growth, NF-κB activation, and inflammation-related gene expression. Thus, IGF-1 and/or NF-κB inhibition may pharmacologically mimic the anticancer effects of CR to break the obesity-colon cancer link.

Distinct effects of calorie restriction on adipose tissue cytokine and angiogenesis profiles in obese and lean mice

Background

Obesity associates with low-grade inflammation and adipose tissue remodeling. Using sensitive high-throughput protein arrays we here investigated adipose tissue cytokine and angiogenesis-related protein profiles from obese and lean mice, and in particular, the influence of calorie restriction (CR).

Methods

Tissue samples from visceral fat were harvested from obese mice fed with a high-fat diet (60% of energy), lean controls receiving low-fat control diet as well as from obese and lean mice kept under CR (energy intake 70% of ad libitum intake) for 50 days. Protein profiles were analyzed using mouse cytokine and angiogenesis protein array kits.

Results

In obese and lean mice, CR was associated with 11.3% and 15.6% reductions in body weight, as well as with 4.0% and 4.6% reductions in body fat percentage, respectively. Obesity induced adipose tissue cytokine expressions, the most highly upregulated cytokines being IL-1ra, IL-2, IL-16, MCP-1, MIG, RANTES, C5a, sICAM-1 and TIMP-1. CR increased sICAM-1 and TIMP-1 expression both in obese and lean mice. Overall, CR showed distinct effects on cytokine expressions; in obese mice CR largely decreased but in lean mice increased adipose tissue cytokine expressions. Obesity was also associated with increased expressions of angiogenesis-related proteins, in particular, angiogenin, endoglin, endostatin, endothelin-1, IGFBP-3, leptin, MMP-3, PAI-1, TIMP-4, CXCL16, platelet factor 4, DPPIV and coagulation factor III. CR increased endoglin, endostatin and platelet factor 4 expressions, and decreased IGFBP-3, NOV, MMP-9, CXCL16 and osteopontin expressions both in obese and lean mice. Interestingly, in obese mice, CR decreased leptin and TIMP-4 expressions, whereas in lean mice their expressions were increased. CR decreased MMP-3 and PAI-1 only in obese mice, whereas CR decreased FGF acidic, FGF basic and coagulation factor III, and increased angiogenin and DPPIV expression only in lean mice.

Conclusions

CR exerts distinct effects on adipocyte cytokine and angiogenesis profiles in obese and lean mice. Our study also underscores the importance of angiogenesis-related proteins and cytokines in adipose tissue remodeling and development of obesity.

Diet-induced obesity alters dendritic cell function in the presence and absence of tumor growth

Obesity is a mounting health concern in the United States and is associated with an increased risk for developing several cancers, including renal cell carcinoma (RCC). Despite this, little is known regarding the impact of obesity on antitumor immunity. Because dendritic cells (DC) are critical regulators of antitumor immunity, we examined the combined effects of obesity and tumor outgrowth on DC function. Using a diet-induced obesity (DIO) model, DC function was evaluated in mice bearing orthotopic RCC and in tumor-free controls. Tumor-free DIO mice had profoundly altered serum cytokine and chemokine profiles, with upregulation of 15 proteins, including IL-1α, IL-17, and LIF. Tumor-free DIO mice had elevated percentages of conventional splenic DC that were impaired in their ability to stimulate naive T cell expansion, although they were phenotypically similar to normal weight (NW) controls. In DIO mice, intrarenal RCC tumor challenge in the absence of therapy led to increased local infiltration by T cell-suppressive DC and accelerated early tumor outgrowth. Following administration of a DC-dependent immunotherapy, established RCC tumors regressed in normal weight mice. The same immunotherapy was ineffective in DIO mice and was characterized by an accumulation of regulatory DC in tumor-bearing kidneys, decreased local infiltration by IFN-γ-producing CD8 T cells, and progressive tumor outgrowth. Our results suggest that the presence of obesity as a comorbidity can impair the efficacy of DC-dependent antitumor immunotherapies.

The impact of obesity on the immune response to infection

There is strong evidence indicating that excess adiposity negatively impacts immune function and host defence in obese individuals. This is a review of research findings concerning the impact of obesity on the immune response to infection, including a discussion of possible mechanisms. Obesity is characterised by a state of low-grade, chronic inflammation in addition to disturbed levels of circulating nutrients and metabolic hormones. The impact of these metabolic abnormalities on obesity-related comorbidities has undergone intense scrutiny over the past decade. However, relatively little is known of how the immune system and host defence are influenced by the pro-inflammatory and excess energy milieu of the obese. Epidemiological data suggest obese human subjects are at greater risk for nosocomial infections, especially following surgery. Additionally, the significance of altered immunity in obese human subjects is emphasised by recent studies reporting obesity to be an independent risk factor for increased morbidity and mortality following infection with the 2009 pandemic influenza A (H1N1) virus. Rodent models offer important insight into how metabolic abnormalities associated with excess body weight can impair immunity. However, more research is necessary to understand the specific aspects of immunity that are impaired and what factors are contributing to reduced immunocompetence in the obese. Additionally, special consideration of how infection in this at-risk population is managed is required, given that this population may not respond optimally to antimicrobial drugs and vaccination. Obesity impacts millions globally, and greater understanding of its associated physiological disturbances is a key public health concern.