Visceral fat accumulation induced by a high-fat diet causes the atrophy of mesenteric lymph nodes in obese mice

Immunotherapy and Overall Survival Among Patients With Advanced Non-Small Cell Lung Cancer and Obesity

IMPORTANCE

The association between obesity and response to cancer treatment and survival remains unclear, with conflicting findings from various studies. The optimal choice between conventional chemotherapy and immunotherapy for first-line treatment remains uncertain in patients with obesity who potentially have an inadequate therapeutic response to immunotherapy.

OBJECTIVE

To investigate whether body mass index (BMI) modifies the association of immunotherapy or conventional therapy with overall survival in patients with advanced non-small cell lung cancer (aNSCLC).

DESIGN, SETTING, and PARTICIPANTS

A retrospective cohort study, using administrative claims data obtained from advanced treatment centers in Japan, was conducted between December 1, 2015, and January 31, 2023. Participants included individuals aged 18 years or older with aNSCLC who received immunotherapy, using immune checkpoint inhibitor (ICI) treatment or conventional chemotherapy.

EXPOSURE

Immune checkpoint inhibitor therapy as first-line chemotherapy was compared with conventional chemotherapy, identified through patient medical records.

MAIN OUTCOMES AND MEASURES

The main outcome was overall survival. Survival analysis covered a 3-year follow-up period after the first-line chemotherapy.

RESULTS

A total of 31 257 patients with aNSCLC were identified. Of these, 12 816 patients received ICI therapy (mean [SD] age, 70.2 [9.1] years; 10 287 [80.3%] men) and 18 441 patients received conventional chemotherapy (mean [SD] age, 70.2 [8.9] years; 14 139 [76.7%] men). Among patients with BMI less than 28, ICI therapy was associated with a significantly lower hazard of mortality (eg, BMI 24: hazard ratio [HR], 0.81; 95% CI, 0.75-0.87) compared with those who underwent conventional chemotherapy. However, no such association was observed among patients with BMI 28 or greater (eg, BMI 28: HR, 0.90; 95% CI, 0.81-1.00).

CONCLUSIONS AND RELEVANCE

The findings of this retrospective cohort study suggest that BMI modifies the association of ICI therapy compared with conventional chemotherapy with overall survival in patients with aNSCLC. A lack of association between ICI therapy and improved survival in patients with aNSCLC and overweight or obesity compared with conventional chemotherapy was observed. This suggests that ICI therapy may not be the optimal first-line therapy for patients with overweight or obesity and the use of conventional chemotherapy should also be considered in such patients.

Metabolic syndrome is independently associated with improved overall survival to first-line therapy with immune checkpoint inhibitors in non-small cell lung cancer

Background

Many co-existing medical conditions may affect the outcome in patients treated with immune checkpoint inhibitors for advanced cancer. There is currently not any information on whether metabolic syndrome (MetS) impacts the clinical outcome in patients treated with immune checkpoint inhibitors (ICIs) for advanced non-small cell line cancer (NSCLC).

Methods

We carried out a single-center retrospective cohort study to determine the effects of MetS on first-line ICI therapy in patients with NSCLC.

Results

One hundred and eighteen consecutive adult patients who received first-line therapy with ICIs and had adequate medical record information for the determination of MetS status and clinical outcomes were included in the study. Twenty-one patients had MetS and 97 did not. There was no significant difference between the two groups in age, gender, smoking history, ECOG performance status, tumor histologic types, pre-therapy use of broad-spectrum antimicrobials, PD-L1 expression, pre-treatment neutrophil:lymphocyte ratio, or proportions of patients who received ICI monotherapy or chemoimmunotherapy. With a median follow-up of 9 months (range 0.5-67), MetS patients enjoyed significantly longer overall survival (HR 0.54, 95% CI: 0.31-0.92) (p = 0.02) but not progression-free survival. The improved outcome was only observed in patients who received ICI monotherapy and not chemoimmunotherapy. MetS predicted for higher probability of survival at 6 months (p = 0.043) and 12 months (p = 0.008). Multivariate analysis indicated that, in addition to the known adverse effects of use of broad-spectrum antimicrobials and the beneficial effects of PD-L1 (Programmed cell death-ligand 1) expression, MetS was independently associated with improved overall survival but not progression-free survival.

Conclusions

Our results suggest that MetS is an independent predictor of treatment outcome in patients who received first-line ICI monotherapy for NSCLC.

PEPITEM modulates leukocyte trafficking to reduce obesity-induced inflammation

Dysregulation of leukocyte trafficking, lipid metabolism, and other metabolic processes are the hallmarks that underpin and drive pathology in obesity. Current clinical management targets alternations in lifestyle choices (e.g. exercise, weight loss) to limit the impact of the disease. Crucially, re-gaining control over the pathogenic cellular and molecular processes may offer an alternative, complementary strategy for obese patients. Here we investigate the impact of the immunopeptide, PEPITEM, on pancreas homeostasis and leukocyte trafficking in mice on high-fed obesogenic diet (HFD). Both prophylactic and therapeutic treatment with PEPITEM alleviated the effects of HFD on the pancreas, reducing pancreatic beta cell size. Moreover, PEPITEM treatment also limited T-cell trafficking (CD4+ T-cells and KLRG1+ CD3+ T-cells) to obese visceral, but not subcutaneous, adipose tissue. Similarly, PEPITEM treatment reduced macrophage numbers within the peritoneal cavity of mice on HFD diet at both 6 and 12 weeks. By contrast, PEPITEM therapy elevated numbers of T and B cells were observed in the secondary lymphoid tissues (e.g. spleen and inguinal lymph node) when compared to the untreated HFD controls. Collectively our data highlights the potential for PEPITEM as a novel therapy to combat the systemic low-grade inflammation experienced in obesity and minimize the impact of obesity on pancreatic homeostasis. Thus, offering an alternative strategy to reduce the risk of developing obesity-related co-morbidities, such as type 2 diabetes mellitus, in individuals at high risk and struggling to control their weight through lifestyle modifications.

Fibroblastic reticular cells in lymph node potentiate white adipose tissue beiging through neuro-immune crosstalk in male mice

Lymph nodes (LNs) are always embedded in the metabolically-active white adipose tissue (WAT), whereas their functional relationship remains obscure. Here, we identify fibroblastic reticular cells (FRCs) in inguinal LNs (iLNs) as a major source of IL-33 in mediating cold-induced beiging and thermogenesis of subcutaneous WAT (scWAT). Depletion of iLNs in male mice results in defective cold-induced beiging of scWAT. Mechanistically, cold-enhanced sympathetic outflow to iLNs activates β1- and β2-adrenergic receptor (AR) signaling in FRCs to facilitate IL-33 release into iLN-surrounding scWAT, where IL-33 activates type 2 immune response to potentiate biogenesis of beige adipocytes. Cold-induced beiging of scWAT is abrogated by selective ablation of IL-33 or β1- and β2-AR in FRCs, or sympathetic denervation of iLNs, whereas replenishment of IL-33 reverses the impaired cold-induced beiging in iLN-deficient mice. Taken together, our study uncovers an unexpected role of FRCs in iLNs in mediating neuro-immune interaction to maintain energy homeostasis.

Association between fat-infiltrated axillary lymph nodes on screening mammography and cardiometabolic disease

Objective

Ectopic fat deposition within and around organs is a stronger predictor of cardiometabolic disease status than body mass index (BMI). Fat deposition within the lymphatic system is poorly understood. This study examined the association between the prevalence of cardiometabolic disease and ectopic fat deposition within axillary lymph nodes (LNs) visualized on screening mammograms.

Methods

A cross-sectional study was conducted on 834 women presenting for full-field digital screening mammography. The status of fat-infiltrated LNs was assessed based on the size and morphology of axillary LNs from screening mammograms. The prevalence of cardiometabolic disease was retrieved from the electronic medical records, including type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia, high blood glucose, cardiovascular disease, stroke, and non-alcoholic fatty liver disease.

Results

Fat-infiltrated axillary LNs were associated with a high prevalence of T2DM among all women (adjusted odds ratio: 3.92, 95% CI: [2.40, 6.60], p-value < 0.001) and in subgroups of women with and without obesity. Utilizing the status of fatty LNs improved the classification of T2DM status in addition to age and BMI (1.4% improvement in the area under the receiver operating characteristic curve).

Conclusion

Fat-infiltrated axillary LNs visualized on screening mammograms were associated with the prevalence of T2DM. If further validated, fat-infiltrated axillary LNs may represent a novel imaging biomarker of T2DM in women undergoing screening mammography.

Nil-Surin Rice Bran Hydrolysates Improve Lipid Metabolism and Hepatic Steatosis by Regulating Secretion of Adipokines and Expression of Lipid-Metabolism Genes

Overconsumption of a high caloric diet is associated with metabolic disorders and a heightened risk of diabetes mellitus (DM), hepatic steatosis, and cardiovascular complications. The use of functional food has received much attention as a strategy in the prevention and treatment of metabolic disorders. This present study investigated whether Nil-Surin rice bran hydrolysates (NRH) could prevent or ameliorate the progression of metabolic disorders in rats in which insulin resistance (IR) was induced by a high fat-high fructose diet (HFFD). After 10 weeks of the HFFD, the rats showed elevated fasting blood glucose (FBG), impaired glucose tolerance, dysregulation of adipokine secretion, distorted lipid metabolism such as dyslipidemia, and increased intrahepatic fat accumulation. The IR was significantly attenuated by a daily dose of NRH (100 or 300 mg/kg/day). Doses of NRH rectified adipokine dysregulation by increasing serum adiponectin and improving hyperleptinemia. Interestingly, NRH decreased intrahepatic fat accumulation and improved dyslipidemia as shown by decreased levels of hepatic triglyceride (TG) and serum TG, total cholesterol and low-density lipoprotein cholesterol, and increased high-density lipoprotein cholesterol. In addition, a modulation of expression of lipid metabolism genes was observed: NRH prevented upregulation of the lipogenesis genes Srebf1 and Fasn. In addition, NRH enhanced the expression of fatty-acid oxidation genes, as evidenced by an increase of Ppara and Cpt1a when compared with the HFFD control group. The activities of NRH in the modulation of lipid metabolism and rectifying the dysregulation of adipokines may result in a decreased risk of DM and hepatic steatosis. Therefore, NRH may be beneficial in ameliorating metabolic disorders in the HFFD model.

Effects of diet-induced obesity in the development of lymphedema in the animal model: A literature review

BACKGROUND

Obesity poses deleterious consequences on every organ system, especially the lymphatic network. However, the underlying cellular mechanisms through which obesity causes lymphatic dysfunction remains unclear. We aimed to summarize experimental studies that evaluated the effect of obesity on the lymphatic system on animal models.

METHODS

We used the following terms to search the Ovid EMBASE, Ovid MEDLINE(R), Cochrane, and Scopus databases: "lymphedema", "lymphatic diseases", "lymphatic system/complications* ", "lymphatic system/injuries* ", "lymphatic system/abnormalities* ", AND "obesity/complications* ", "diet/high-fat", "adipogenesis" and "lipid metabolism disorder". From a total of 166 articles identified in the initial search, 13 met our eligibility criteria.

RESULTS

Long-term exposure to high-fat diet in mice demonstrated significant amount of adipose tissue deposition which sets off an inflammatory cascade resulting in disruption of the chemokine gradient, inhibition of lymphangiogenesis, and changes in gene expression of lymphatic endothelial cells, that alter vessel permeability and induce cell death. Reduced contractile properties of lymphatic collectors, dilated capillaries, increased tissue pressure, and reduced hydraulic conductivity collectively contribute to reduced impaired lymphatic drainage. Aerobic exercise has shown reversal of lymphatic dysfunction in the obese and pharmacological interventions targeting T-cells, iNOS and VEGFR-3 signaling have the potential to combat acquired lymphedema.

CONCLUSION

Scientists should focus their future experiments on developing therapies that regulate expression of T-cell derived cytokines and VEGFR-3 expression whereas clinicians are urged to counsel their patients to reduce weight through aerobic exercise.

High-Fat Diet Rapidly Modifies Trafficking, Phenotype, and Function of Plasmacytoid Dendritic Cells in Adipose Tissue

Plasmacytoid dendritic cells (pDCs) display an increased abundance in visceral adipose tissue (VAT) of humans with obesity. In the current study, we set out to decipher the molecular mechanisms of their recruitment to VAT and the functional relevance of this process. We observed increased pDC numbers in murine blood, liver, spleen, and VAT after feeding a high-fat diet (HFD) for 3 wk when compared with a standard diet. pDCs were enriched in fat-associated lymphoid clusters representing highly specific lymphoid regions within VAT. HFD led to an enlargement of fat-associated lymphoid clusters with an increased density and migratory speed of pDCs as shown by intravital multiphoton microscopy. For their recruitment into VAT, pDCs employed P-selectin with E-selectin and L-selectin being only critical in response to HFD, indicating that the molecular cues underlying pDC trafficking were dependent on the nutritional state. Subsequent recruitment steps required α₄β₁ and α₄β₇ integrins and engagement of CCR7. Application of fingolimod (FTY720) abrogated egress of pDCs from VAT, indicating the involvement of sphingosine-1-phosphate in this process. Furthermore, HFD altered pDC functions by promoting their activation and type 1 IFN expression. Blocking pDC infiltration into VAT prevented weight gain and improved glucose tolerance during HFD. In summary, a HFD fundamentally alters pDC biology by promoting their trafficking, retention, and activation in VAT, which in turn seems to regulate metabolism.

Non-alcoholic fatty liver disease and intestinal immune status: a narrative review

Background and objectives: Non-alcoholic fatty liver disease (NAFLD) interacts with the gut immunity. However, the mechanisms underlying alternations of intestinal immune system in NAFLD remains unclear. To date, no effective medical interventions exist that completely reverse the disease. In this review, we mainly elaborates on the impact of NAFLD on intestinal immune cells and briefly summarize the new treatment methods for NAFLD targeting at intestinal immune cells.Methods: We searched MEDLINE, EMBASE and Web of Science for English-language sources. The preferred citations were meta-analyses and systematic or narrative reviews. Citation tracking was completed for all identified studies included in the refined library, using Google Scholar. No restriction was placed on the year of publication for the included reports.Results: The intestinal immune imbalance promotes liver inflammation and fibrosis in the process of NAFLD, and meanwhile, NAFLD influences disorders of immune cells in the liver and intestinal tract. Biological agents targeting at intestinal immunity has been shown in preclinical studies to be an effective method for systemic immune modulation and alleviates immune-mediated injury.Conclusions: Intestinal immune disorder plays an important role in triggering and amplifying hepatic inflammation in NAFLD. Advances in knowledge of the gut-liver axis are driving the development of diagnostic, prognostic and therapeutic tools based on intestine immunity for the management of NAFLD.

Decrease in the Size of Fat-Enlarged Axillary Lymph Nodes and Serum Lipids after Bariatric Surgery

BACKGROUND

Ectopic fat deposition in obesity is associated with organ dysfunction; however, little is known about fat deposition within the lymphatic system and associated lymphatic dysfunction.

METHODS

One hundred fifty-five women who underwent routine screening mammography before and after a Roux-en-y gastric bypass or a sleeve gastrectomy were retrospectively reviewed and after excluding women without visible nodes both before and after bariatric surgery, 84 patients were included in the final analysis. Axillary lymph node size, patient weight in kilograms, body mass index, and a diagnosis of hypertension, type 2 diabetes, and dyslipidemia were evaluated before and after surgery. Binary linear regression models and Fischer's exact test were used to evaluate the relationship between the size of fat-infiltrated axillary lymph nodes, patient age, change in patient weight, and diagnosis of hypertension, type 2 diabetes, and dyslipidemia.

RESULTS

Fat-infiltrated axillary lymph nodes demonstrated a statistically significant decrease in size after bariatric surgery with a mean decrease of 4.23 mm (95% CI: 3.23 to 5.2, p < 0.001). The resolution of dyslipidemia was associated with a decrease in lymph node size independent of weight loss (p = 0.006).

CONCLUSIONS

Mammographically visualized fat-infiltrated axillary lymph nodes demonstrated a statistically significant decrease in size after bariatric surgery. The decrease in lymph node size was significantly associated with the resolution of dyslipidemia, independent of weight loss, age, and type of surgery.

Fatty Acid Metabolism Reprogramming in Advanced Prostate Cancer

Prostate cancer (PCa) is a carcinoma in which fatty acids are abundant. Fatty acid metabolism is rewired during PCa development. Although PCa can be treated with hormone therapy, after prolonged treatment, castration-resistant prostate cancer can develop and can lead to increased mortality. Changes to fatty acid metabolism occur systemically and locally in prostate cancer patients, and understanding these changes may lead to individualized treatments, especially in advanced, castration-resistant prostate cancers. The fatty acid metabolic changes are not merely reflective of oncogenic activity, but in many cases, these represent a critical factor in cancer initiation and development. In this review, we analyzed the literature regarding systemic changes to fatty acid metabolism in PCa patients and how these changes relate to obesity, diet, circulating metabolites, and peri-prostatic adipose tissue. We also analyzed cellular fatty acid metabolism in prostate cancer, including fatty acid uptake, de novo lipogenesis, fatty acid elongation, and oxidation. This review broadens our view of fatty acid switches in PCa and presents potential candidates for PCa treatment and diagnosis.

Re-Evaluating the Effects of Obesity on Cancer Immunotherapy Outcomes in Renal Cancer: What Do We Really Know?

Obesity has reached global epidemic proportions and its effects on interactions between the immune system and malignancies, particularly as related to cancer immunotherapy outcomes, have come under increasing scrutiny. Although the vast majority of pre-clinical murine studies suggest that host obesity should have detrimental effects on anti-tumor immunity and cancer immunotherapy outcomes, the opposite has been found in multiple retrospective human studies. As a result, acceptance of the "obesity paradox" paradigm, wherein obesity increases cancer risk but then improves patient outcomes, has become widespread. However, results to the contrary do exist and the biological mechanisms that promote beneficial obesity-associated outcomes remain unclear. Here, we highlight discrepancies in the literature regarding the obesity paradox for cancer immunotherapy outcomes, with a particular focus on renal cancer. We also discuss multiple factors that may impact research findings and warrant renewed research attention in future studies. We propose that specific cancer patient populations may be affected in fundamentally different ways by host obesity, leading to divergent effects on anti-tumor immunity and/or immunotherapy outcomes. Continued, thoughtful analysis of this critical issue is therefore needed to permit a more nuanced understanding of the complex effects of host obesity on cancer immunotherapy outcomes in patients with renal cancer or other malignancies.

Type I Interferons as Joint Regulators of Tumor Growth and Obesity

Simple Summary

The escalating global epidemic of overweight and obesity is a major public health and economic problem, as excess body weight represents a significant risk factor for several chronic diseases including cancer. Despite the strong scientific evidence for a link between obesity and cancer, the mechanisms involved in this interplay have not yet been fully understood. The aim of this review is to evaluate the role of type I interferons, a family of antiviral cytokines with key roles in the regulation of both obesity and cancer, highlighting how the dysregulation of the interferon system can differently affect these pathological conditions.

Abstract

Type I interferons (IFN-I) are antiviral cytokines endowed with multiple biological actions, including antitumor activity. Studies in mouse models and cancer patients support the concept that endogenous IFN-I play important roles in the control of tumor development and growth as well as in response to several chemotherapy/radiotherapy treatments. While IFN-I signatures in the tumor microenvironment are often considered as biomarkers for a good prognostic response to antitumor therapies, prolonged IFN-I signaling can lead to immune dysfunction, thereby promoting pathogen or tumor persistence, thus revealing the “Janus face” of these cytokines in cancer control, likely depending on timing, tissue microenvironment and cumulative levels of IFN-I signals. Likewise, IFN-I exhibit different and even opposite effects on obesity, a pathologic condition linked to cancer development and growth. As an example, evidence obtained in mouse models shows that localized expression of IFN-I in the adipose tissue results in inhibition of diet–induced obesity, while hyper-production of these cytokines by specialized cells such as plasmacytoid dendritic cells in the same tissue, can induce systemic inflammatory responses leading to obesity. Further studies in mouse models and humans should reveal the mechanisms by which IFN-I can regulate both tumor growth and obesity and to understand the role of factors such as genetic background, diet and microbioma in shaping the production and action of these cytokines under physiological and pathological conditions.

Antiobesity and anti-inflammation effects of Hakka stir-fried tea of different storage years on high-fat diet-induced obese mice model via activating the AMPK/ACC/CPT1 pathway

Background

As a typical representative of metabolic syndrome, obesity is also one of the extremely dangerous factors of cardiovascular diseases. Thus, the prevention and treatment of obesity has gradually become a global campaign. There have been many reports that green tea is effective in preventing obesity, but as a kind of green tea with regional characteristics, there have been no reports that Hakka stir-fried tea (HT) of different storage years has a weight loss effect.

Aims

The aim was to investigate the effect of HT in diet-induced obese mice.

Methods

The mice were divided into five groups as follows: the control group received normal diet; the obese model group received high-fat diet; and HT2003, HT2008, and HT2015 groups, after the induction of obesity via a high-fat diet, received HT of different storage years treatment for 6 weeks, respectively.

Results

It was observed that HT decreased the levels of serum and liver triglyceride; the ratio of liver to body weight; accumulation of epididymal, perirenal, and mesenteric fat; the degree of hepatic steatosis; and adipocyte hypertrophy, with the concomitant reduction of body weight. Moreover, HT decreased the expression levels of proinflammatory cytokines tumor necrosis factor α (TNF α), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and reduced fatty acid synthase (FAS) activity in liver tissue of obese mice. In addition, HT treatment also increased the phosphorylation of AMP-activated protein kinase (AMPK) and its direct downstream proteins, acetyl coenzyme A carboxylase (ACC), and carnitine palmitoyltransferase I (CPT-1), which participate in FAS pathway.

Conclusions

These findings demonstrate that HT treatment has a potential protection on high-fat diet-induced obesity mice via activating the AMPK/ACC/CPT1 pathway, and to a certain extent, it has nothing to do with the storage time of three kinds of HT.

Dietary lipids accumulate in macrophages and stromal cells and change the microarchitecture of mesenteric lymph nodes

In obesity, increased dietary lipids are taken up and transported by the lymphatic systems into the circulatory system. Increased fat accumulation results in impairments in the lymph fluid and lymph node (LN) atrophy. LNs filter the lymph fluid for foreign antigens to induce and control immune responses, and the alteration of this function during obesity remains underexplored. Here, the changes within the microarchitecture of mesenteric LNs (mLNs) during high levels of lipid transport were investigated, and the role of stromal cells in mice fed a high-fat diet for 10 weeks was assessed. Microarray experiments revealed that gene probes involved in lipid metabolism are expressed by mLN stromal cells. Transmission electron microscopy enabled the identification of lipid droplets in lymphatic endothelial cells, different reticulum cells, and macrophages, and the lipid droplet sizes as well as their numbers and intercellular distances increased after 10 weeks of high-fat diet feeding. The results indicate that changes in the microarchitecture and increased accumulation of lipid droplets in stromal cells and macrophages influence the immunological function of mLNs.

B Lymphocytes and Adipose Tissue Inflammation

The immune system plays an important role in obesity-induced adipose tissue inflammation and the resultant metabolic dysfunction, which can lead to hypertension, dyslipidemia, and insulin resistance and their downstream sequelae of type 2 diabetes mellitus and cardiovascular disease. While macrophages are the most abundant immune cell type in adipose tissue, other immune cells are also present, such as B cells, which play important roles in regulating adipose tissue inflammation. This brief review will overview B-cell subsets, describe their localization in various adipose depots and summarize our knowledge about the function of these B-cell subsets in regulating adipose tissue inflammation, obesity-induced metabolic dysfunction and atherosclerosis.

WWP1 knockout in mice exacerbates obesity-related phenotypes in white adipose tissue but improves whole-body glucose metabolism

White adipose tissue (WAT) is important for maintenance of homeostasis, because it stores energy and secretes adipokines. The WAT of obese people demonstrates mitochondrial dysfunction, accompanied by oxidative stress, which leads to insulin resistance. WW domain-containing E3 ubiquitin protein ligase 1 (WWP1) is a member of the HECT-type E3 family of ubiquitin ligases and is associated with several diseases. Recently, we demonstrated that WWP1 is induced specifically in the WAT of obese mice, where it protects against oxidative stress. Here, we investigated the function of WWP1 in WAT of obese mice by analyzing the phenotype of Wwp1 knockout (KO) mice fed a high-fat diet. The levels of oxidative stress markers were higher in obese WAT from Wwp1 KO mice. Moreover, Wwp1 KO mice had lower activity of citrate synthase, a mitochondrial enzyme. We also measured AKT phosphorylation in obese WAT and found lower levels in Wwp1 KO mice. However, plasma insulin level was low and glucose level was unchanged in obese Wwp1 KO mice. Moreover, both glucose tolerance test and insulin tolerance test were improved in obese Wwp1 KO mice. These findings indicate that WWP1 participates in the antioxidative response and mitochondrial function in WAT, but knockdown of WWP1 improves whole-body glucose metabolism.

High-fat diet induced central adiposity (visceral fat) is associated with increased fibrosis and decreased immune cellularity of the mesenteric lymph node in mice

PURPOSE

Accumulation of visceral, but not subcutaneous, adipose tissue is highly associated with metabolic disease. Inflammation inciting from adipose tissue is commonly associated with metabolic disease risk and comorbidities. However, constituents of the immune system, lymph nodes, embedded within these adipose depots remain under-investigated. We hypothesize that, lymph nodes are inherently distinct and differentially respond to diet-induced obesity much like the adipose depots they reside in.

METHODS

Adipose tissue and lymph nodes were collected from the visceral and inguinal depots of male mice fed 13 weeks of standard CHOW or high fat diet (HFD). Immune cells were isolated from tissues, counted and characterized by flow cytometry or plated for proliferative capacity following Concanavalin A stimulation. Lymph node size and fibrosis area were also characterized.

RESULTS

In HFD fed mice visceral adipose tissue accumulation was associated with significant enlargement of the lymph node encased within. The subcutaneous lymph node did not change. Compared with mice fed CHOW for 13 weeks, mice fed HFD had a decline in immune cell populations and immune cell proliferative ability, as well as, exacerbated fibrosis accumulation, within the visceral, but not subcutaneous, lymph node.

CONCLUSIONS

Obesity-induced chronic low-grade inflammation is associated with impaired immunity and increased susceptibility to disease. Excessive visceral adiposity and associated inflammation driven by diet likely leads to obesity-induced immune suppression by way of lymph node/lymphatic system pathophysiology.

Obesity-induced immune dysfunction and immunosuppression: TEM observation of visceral and subcutaneous lymph node microarchitecture and immune cell interactions

Background Inflammation, induced by excessive adiposity, links obesity to disease risk yet little attention has been devoted to the lymphoid tissues embedded within adipose tissue depots. Lymph nodes are the primary site for the development of protective immunity, hence any disease process that affects these tissues will also directly impact immunity. Here we examined how obesity alters secondary lymphatic tissue structure and encapsulated immune cells. Materials and methods Four-month-old C57BL/6 male mice were fed standard rodent chow or a Western high fat diet (HFD) for 6 months. Center regions of visceral and subcutaneous lymph nodes (SQLNS) were observed via transmission electron microscopy (TEM). Results Compared with chow, HFD-induced obesity deleteriously modified the structural microarchitecture and immune cell morphology of visceral and SQLNs. In HFD mice, fibroblastic reticular cells (FRCs) were dysregulated while laying among excessive amounts of disorganized collagen (C). In addition HFD lymph nodes contained a disproportionate amount of cellular debris from damaged or dead cells, increased sinus spacing and decreased immune cell interactions. Specifically, dendritic cells (DCs) that are necessary for adaptive immune response where embedded among extracellular debris with decreased pseudopodia. Similarly, the extraneous fibrous extracellular matrix (ECM) in HFD mice limited contact between lymphocytes (LCs) causing their microvilli extensions to decrease. Discussion Overall, excessive C production within lymph nodes, driven by diet-induced obesity, creates a physical barrier that impedes proper lymph flow and cellular communication. Obesity-induced disorganization of the immune cell guidance network interrupts immune cell adhesion and consequently inhibits travel within cortex regions needed for cell interactions, survival and proliferation.

Mesenteric lymph node CD4+ T lymphocytes migrate to liver and contribute to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by altered intestinal microbiota and intestinal immune disorder. Here we investigated the role of mesenteric lymph node (MLN) CD4⁺ T lymphocytes in NAFLD. In high fat diet (HFD)-fed mice, the percentage ratios of Th1 to Th2 cells and Th17 to Treg cells were imbalanced in MLNs. Co-culture assays showed MLN CD4⁺ T lymphocytes from HFD-fed mice tended to migrate to the liver and promoted hepatic inflammation. Adoptive transfer of MLN CD4⁺ T lymphocytes from NAFLD mice to HFD-fed mice resulted in higher transaminase, worse hepatic inflammation and lipid accumulation. Antibiotics and probiotics were administrated to regulate intestinal microbiota, and the restoration of MLN Th1/Th2 and Th17/Treg cells in alleviated NAFLD were found. In summary, MLNs CD4⁺ T subtype cells may involve in NAFLD, and the restoration of MLN CD4⁺ T subtype cells ratio by regulating intestinal bacteria could be the new strategies.

Obesity associated disease risk: the role of inherent differences and location of adipose depots

Obesity and associated metabolic co-morbidities are a worldwide public health problem. Negative health outcomes associated with obesity, however, do not arise from excessive adiposity alone. Rather, deleterious outcomes of adipose tissue accumulation are a result of how adipocytes are distributed to individual regions in the body. Due to our increased understanding of the dynamic relationship that exists between specific adipose depots and disease risk, an accurate characterization of total body adiposity as well as location is required to properly evaluate a population's disease risk. Specifically, distinctive tissue depots within the body include the lower body, upper body and abdominal (deep and superficial) subcutaneous regions, as well as visceral (mesenteric and omental) regions. Upper body and visceral adipose tissues are highly associated with metabolic dysfunction and chronic disease development, whereas lower body gluteofemoral subcutaneous adipose tissue imparts protection against diet-induced metabolic derangement. Each adipose depot functions distinctly as an endocrine organ hence it has a different level of impact on health outcomes. Effluent from adipose tissue can modulate the functions of other tissues, whilst receiving differential communication from the rest of the body via central nervous system innervation, metabolites and other signaling molecules. More so, adipose depots contain a diverse reservoir of tissue-resident immune cells that play an integral part in both maintaining tissue homeostasis, as well as propagating metabolically-induced inflammation. Overall, the conceptualization of obesity and associated risks needs updating to reflect the complexities of obesity. We review adipose tissue characteristics that are linked to deleterious or beneficial adipose tissue distributions.

Correlation between obesity and fat-infiltrated axillary lymph nodes visualized on mammography

OBJECTIVE

Using screening mammography, this study investigated the association between obesity and axillary lymph node (LN) size and morphology.

METHODS

We conducted a retrospective review of 188 females who underwent screening mammography at an academic medical centre. Length and width of the LN and hilum were measured in the largest, mammographically visible axillary node. The hilo-cortical ratio (HCR) was calculated as the hilar width divided by the cortical width. Measurements were performed by a board certified breast radiologist and a resident radiology physician. Inter-rater agreement was assessed with Pearson correlation coefficient. We performed multivariable regression analysis for associations of LN measurements with body mass index (BMI), breast density and age.

RESULTS

There was a strong association between BMI and LN dimensions, hilum dimensions and HCR (p < 0.001 for all metrics). There was no significant change in cortex width with increasing BMI (p = 0.15). Increases in LN length and width were found with increasing BMI [0.6 mm increase in length per unit BMI, 95% CI (0.4-0.8), p < 0.001 and0.3 mm increase in width per unit BMI, 95% CI(0.2-0.4), p < 0.001, respectively]. Inter-rater reliability for lymph node and hilum measurements was 0.57-0.72.

CONCLUSION

We found a highly significant association between increasing BMI and axillary LN dimensions independent of age and breast density with strong interobserver agreement. The increase in LN size was driven by expansion of the LN hilum secondary to fat infiltration. Advances in knowledge: This preliminary work determined a relationship between fat infiltrated axillary lymph nodes and obesity.

Diet-induced obesity causes visceral, but not subcutaneous, lymph node hyperplasia via increases in specific immune cell populations

OBJECTIVES

The spatial proximity of adipose depots to secondary lymph nodes allows a unique relation between the two systems. Obesity, predominately visceral adiposity, links to numerous diseases; hence, we postulate that secondary lymphatics within this region contributes to disease risk.

MATERIAL AND METHODS

Male C57BL/6 mice were fed standard CHOW (18% kcal fat) or Western diet (45% kcal fat) for 7 weeks. Visceral and subcutaneous lymph nodes and associated adipose depots they occupy were excised. Lymph node morphology and resident immune cell populations were characterized via histopathology, immunofluorescence and flow cytometry. Adipose tissue immune cell populations were also characterized.

RESULTS

Obesity caused lymph node expansion, increased viable cell number and deviations in immune cell populations. These alterations were exclusive to visceral lymph nodes. Notably, pro-inflammatory antigen presenting cells and regulatory T cells increased in number in the visceral lymph node. Obesity, however, reduced T regulatory cells in visceral lymph nodes. The visceral adipose depot also had greater reactivity towards HFD than subcutaneous, with a greater percent of macrophages, dendritic and CD8⁺ T cells. Immune cell number, in both the visceral and subcutaneous, however decreased as adipose depots enlarged.

CONCLUSION

Overall, HFD has a greater influence on visceral cavity than the subcutaneous. In the visceral lymph node, but not subcutaneous, HFD-induced obesity decreased cell populations that suppressed immune function while increasing those that regulate/activate immune response.

High-Fat Diet in the Absence of Obesity Does Not Aggravate Surgically Induced Lymphoedema in Mice

BACKGROUND

Lymphoedema represents the cardinal manifestation of lymphatic dysfunction and is associated with expansion of the adipose tissue in the affected limb. In mice, high-fat diet (HFD)-induced obesity was associated with impaired collecting lymphatic vessel function, and adiposity aggravated surgery-induced lymphoedema in a mouse model. The aim of the current study was to investigate whether adiposity is necessary to impair lymphatic function or whether increased lipid exposure alone might be sufficient in a surgical lymphoedema model.

METHODS

To investigate the role of increased lipid exposure in lymphoedema development we used a well-established mouse tail lymphoedema model. Female mice were subjected to a short-term (6 weeks) HFD, without development of obesity, before surgical induction of lymphedema. Lymphoedema was followed over a period of 6 weeks measuring oedema, evaluating tissue histology and lymphatic vascular function.

RESULTS

HFD increased baseline angiogenesis and average lymphatic vessel size in comparison to the chow control group. Upon induction of lymphedema, HFD-treated mice did not exhibit aggravated oedema and no morphological differences were observed in the blood and lymphatic vasculature. Importantly, the levels of fibro-adipose tissue deposition were comparable between the 2 groups and lymphatic vessel function was not impaired as a result of the HFD. Although the net immune cell infiltration was comparable, the HFD group displayed an increased infiltration of macrophages, which exhibited an M2 polarization phenotype.

CONCLUSIONS

These results indicate that increased adiposity rather than dietary influences determines predisposition to or severity of lymphedema.

Exercise training improves obesity-related lymphatic dysfunction

Key points

Obesity results in perilymphatic inflammation and lymphatic dysfunction.

Lymphatic dysfunction in obesity is characterized by decreased lymphatic vessel density, decreased collecting lymphatic vessel pumping frequency, decreased lymphatic trafficking of immune cells, increased lymphatic vessel leakiness and changes in the gene expression patterns of lymphatic endothelial cells.

Aerobic exercise, independent of weight loss, decreases perilymphatic inflammatory cell accumulation, improves lymphatic function and reverses pathological changes in gene expression in lymphatic endothelial cells.

Abstract

Although previous studies have shown that obesity markedly decreases lymphatic function, the cellular mechanisms that regulate this response remain unknown. In addition, it is unclear whether the pathological effects of obesity on the lymphatic system are reversible with behavioural modifications. The purpose of this study, therefore, was to analyse lymphatic vascular changes in obese mice and to determine whether these pathological effects are reversible with aerobic exercise. We randomized obese mice to either aerobic exercise (treadmill running for 30 min per day, 5 days a week, for 6 weeks) or a sedentary group that was not exercised and analysed lymphatic function using a variety of outcomes. We found that sedentary obese mice had markedly decreased collecting lymphatic vessel pumping capacity, decreased lymphatic vessel density, decreased lymphatic migration of immune cells, increased lymphatic vessel leakiness and decreased expression of lymphatic specific markers compared with lean mice (all P < 0.01). Aerobic exercise did not cause weight loss but markedly improved lymphatic function compared with sedentary obese mice. Exercise had a significant anti‐inflammatory effect, resulting in decreased perilymphatic accumulation of inflammatory cells and inducible nitric oxide synthase expression. In addition, exercise normalized isolated lymphatic endothelial cell gene expression of lymphatic specific genes, including VEGFR‐3 and Prox1. Taken together, our findings suggest that obesity impairs lymphatic function via multiple mechanisms and that these pathological changes can be reversed, in part, with aerobic exercise, independent of weight loss. In addition, our study shows that obesity‐induced lymphatic endothelial cell gene expression changes are reversible with behavioural modifications.

Obesity results in perilymphatic inflammation and lymphatic dysfunction.

Lymphatic dysfunction in obesity is characterized by decreased lymphatic vessel density, decreased collecting lymphatic vessel pumping frequency, decreased lymphatic trafficking of immune cells, increased lymphatic vessel leakiness and changes in the gene expression patterns of lymphatic endothelial cells.

Aerobic exercise, independent of weight loss, decreases perilymphatic inflammatory cell accumulation, improves lymphatic function and reverses pathological changes in gene expression in lymphatic endothelial cells.

Impact of Obesity and Metabolic Syndrome on Immunity

Obesity is associated with metabolic disturbances that cause tissue stress and dysfunction. Obese individuals are at a greater risk for chronic disease and often present with clinical parameters of metabolic syndrome (MetS), insulin resistance, and systemic markers of chronic low-grade inflammation. It has been well established that cells of the immune system play an important role in the pathogenesis of obesity- and MetS-related chronic diseases, as evidenced by leukocyte activation and dysfunction in metabolic tissues such as adipose tissue, liver, pancreas, and the vasculature. However, recent findings have highlighted the substantial impact that obesity and MetS parameters have on immunity and pathogen defense, including the disruption of lymphoid tissue integrity; alterations in leukocyte development, phenotypes, and activity; and the coordination of innate and adaptive immune responses. These changes are associated with an overall negative impact on chronic disease progression, immunity from infection, and vaccine efficacy. This review presents an overview of the impact that obesity and MetS parameters have on immune system function.

CD36 deficiency blunts effects of diet on regulatory T cells in murine gonadal adipose tissue and mesenteric lymph nodes

The effect of cluster of differentiation (CD)36 on regulatory T cells (Treg) was investigated in gonadal (GN) adipose tissues and mesenteric lymph nodes (MLN) of wild-type (WT) and CD36 deficient (CD36(-/-)) mice kept on standard fat (SFD, lean) or on high fat diet (HFD, obese). GN adipose tissue mass was smaller, but MLN size larger for obese CD36(-/-) versus obese WT mice. Overall, the reduction of Treg cells in GN adipose tissue and MLN after a HFD is much more prominent in WT than CD36(-/-) mice. Moreover, CD36(-/-) mice may be protected against obesity-related chronic inflammation.

Rice Bran Protein Hydrolysates Improve Insulin Resistance and Decrease Pro-inflammatory Cytokine Gene Expression in Rats Fed a High Carbohydrate-High Fat Diet

A high carbohydrate-high fat (HCHF) diet causes insulin resistance (IR) and metabolic syndrome (MS). Rice bran has been demonstrated to have anti-dyslipidemic and anti-atherogenic properties in an obese mouse model. In the present study, we investigated the beneficial effects of rice bran protein hydrolysates (RBP) in HCHF-induced MS rats. After 12 weeks on this diet, the HCHF-fed group was divided into four subgroups, which were orally administered RBP 100 or 500 mg/kg, pioglitazone 10 mg/kg, or tap water for a further 6 weeks. Compared with normal diet control group, the MS rats had elevated levels of blood glucose, lipid, insulin, and HOMA-IR. Treatment with RBP significantly alleviated all those changes and restored insulin sensitivity. Additionally, RBP treatment increased adiponectin and suppressed leptin levels. Expression of Ppar-γ mRNA in adipose tissues was significantly increased whereas expression of lipogenic genes Srebf1 and Fasn was significantly decreased. Levels of mRNA of proinflammatory cytokines, Il-6, Tnf-α, Nos-2 and Mcp-1 were significantly decreased. In conclusion, the present findings support the consumption of RBP as a functional food to improve insulin resistance and to prevent the development of metabolic syndrome.

The gut-adipose-liver axis in the metabolic syndrome

Obesity is associated with altered gut microbiota composition and impaired gut barrier function. These changes, together with interrelated mesenteric adipose tissue inflammation, result in increased release of pro-inflammatory cytokines, bacteria-derived factors, and lipids into the portal circulation, promoting the development of (hepatic) insulin resistance. Herein, the potential impact of obesity-related changes in gut and visceral adipose tissue biology on the development of insulin resistance and Type 2 diabetes is reviewed.

Dysbiosis gut microbiota associated with inflammation and impaired mucosal immune function in intestine of humans with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has recently been considered to be under the influence of the gut microbiota, which might exert toxic effects on the human host after intestinal absorption and delivery to the liver via the portal vein. In this study, the composition of the gut microbiota in NAFLD patients and healthy subjects was determined via 16S ribosomal RNA Illumina next-generation sequencing. Among those taxa displaying greater than 0.1% average abundance in all samples, five genera, including Alistipes and Prevotella, were significantly more abundant in the gut microbiota of healthy subjects compared to NAFLD patients. Alternatively, Escherichia, Anaerobacter, Lactobacillus and Streptococcus were increased in the gut microbiota of NAFLD patients compared to healthy subjects. In addition, decreased numbers of CD4+ and CD8+ T lymphocytes and increased levels of TNF-α, IL-6 and IFN-γ were detected in the NAFLD group compared to the healthy group. Furthermore, irregularly arranged microvilli and widened tight junctions were observed in the gut mucosa of the NAFLD patients via transmission electron microscopy. We postulate that aside from dysbiosis of the gut microbiota, gut microbiota-mediated inflammation of the intestinal mucosa and the related impairment in mucosal immune function play an important role in the pathogenesis of NAFLD.

An emerging player in knee osteoarthritis: the infrapatellar fat pad

The role of inflammation in the development, progression, and clinical features of osteoarthritis has become an area of intense research in recent years. This led to the recognition of synovitis as an important source of inflammation in the joint and indicated that synovitis is intimately associated with pain and osteoarthritis progression. In this review, we discuss another emerging source of inflammation that could play a role in disease development/progression: the infrapatellar fat pad (IFP). The aim of this review is to offer a comprehensive view of the pathology of IFP as obtained from magnetic resonance studies, along with its characterization at both the cellular and the molecular level. Furthermore, we discuss the possible function of this organ in the pathological processes in the knee by summarizing the knowledge regarding the interactions between IFP and other joint tissues and discussing the pro- versus anti-inflammatory functions this tissue could have. We hope that this review will offer an overview of all published data regarding the IFP and will indicate novel directions for future research.

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.

The impact of visceral obesity on surgical outcomes of laparoscopic surgery for colon cancer

PURPOSE

Although obesity is considered as a risk factor for postoperative morbidity in abdominal surgery, its effect on the outcomes of laparoscopic-assisted colectomy (LAC) is still unclear. The technical difficulty and risk factor for postoperative complication in LAC are thought to be influenced by visceral obesity. The aim of this prospective study was to evaluate the impact of visceral fat on the surgical outcomes of LAC.

METHODS

Between April 2005 and December 2010, consecutive patients with preoperatively diagnosed colon cancer, excluding medium and low rectal cancer, who underwent LAC, were enrolled. Their visceral fat area (VFA) and body mass index (BMI) were prospectively collected. The VFA was assessed by Fat Scan software. The patients were classified into two groups as follows: VFA nonobese with VFA <100 cm(2) (VNO) and VFA obese with VFA ≧100 cm(2) (VO). The predictive factors for surgical complications of LAC were evaluated by univariate and logistic regression analyses.

RESULTS

A total of 338 consecutive patients were enrolled in this study. Of the 338 patients, 194 (57.4 %) and 138 (42.6 %) were classified into the VNO and VO groups, respectively. Logistic regression analysis showed that high BMI (≧25 kg/m(2)) and VO independently predicted the incidence of overall postoperative complications (p = 0.040 and 0.007, respectively). VO was more highly related to the incidence of overall postoperative complications, anastomotic leakage (p = 0.021), and surgical site infection (SSI) (p = 0.013) than high BMI.

CONCLUSIONS

VFA is a more useful parameter than BMI in predicting surgical outcomes after LAC.

Obesity impairs lymphatic fluid transport and dendritic cell migration to lymph nodes

INTRODUCTION

Obesity is a major cause of morbidity and mortality resulting in pathologic changes in virtually every organ system. Although the cardiovascular system has been a focus of intense study, the effects of obesity on the lymphatic system remain essentially unknown. The purpose of this study was to identify the pathologic consequences of diet induced obesity (DIO) on the lymphatic system.

METHODS

Adult male wild-type or RAG C57B6-6J mice were fed a high fat (60%) or normal chow diet for 8-10 weeks followed by analysis of lymphatic transport capacity. In addition, we assessed migration of dendritic cells (DCs) to local lymph nodes, lymph node architecture, and lymph node cellular make up.

RESULTS

High fat diet resulted in obesity in both wild-type and RAG mice and significantly impaired lymphatic fluid transport and lymph node uptake; interestingly, obese wild-type but not obese RAG mice had significantly impaired migration of DCs to the peripheral lymph nodes. Obesity also resulted in significant changes in the macro and microscopic anatomy of lymph nodes as reflected by a marked decrease in size of inguinal lymph nodes (3.4-fold), decreased number of lymph node lymphatics (1.6-fold), loss of follicular pattern of B cells, and dysregulation of CCL21 expression gradients. Finally, obesity resulted in a significant decrease in the number of lymph node T cells and increased number of B cells and macrophages.

CONCLUSIONS

Obesity has significant negative effects on lymphatic transport, DC cell migration, and lymph node architecture. Loss of T and B cell inflammatory reactions does not protect from impaired lymphatic fluid transport but preserves DC migration capacity. Future studies are needed to determine how the interplay between diet, obesity, and the lymphatic system modulate systemic complications of obesity.

Metabolic and immunomodulatory effects of n-3 fatty acids are different in mesenteric and epididymal adipose tissue of diet-induced obese mice

In studies emphasizing antiobesogenic and anti-inflammatory effects of long-chain n-3 polyunsaturated fatty acids (LC-n-3 PUFA), diets with very high fat content, not well-defined fat quality, and extreme n-6/n-3 PUFA ratios have been applied frequently. Additionally, comparative analyses of visceral adipose tissues (VAT) were neglected. Considering the link of visceral obesity to insulin resistance or inflammatory bowel diseases, we hypothesized that VAT, especially mesenteric adipose tissue (MAT), may exhibit differential responsiveness to diets through modulation of metabolic and inflammatory processes. Here, we aimed to assess dietary LC-n-3 PUFA effects on MAT and epididymal adipose tissue (EAT) and on MAT-adjacent liver and intestine in diet-induced obese mice fed defined soybean/palm oil-based diets. High-fat (HF) and LC-n-3 PUFA-enriched high-fat diet (HF/n-3) contained moderately high fat with unbalanced and balanced n-6/n-3 PUFA ratios, respectively. Body composition/organ analyses, glucose tolerance test, measurements of insulin, lipids, mRNA and protein expression, and immunohistochemistry were applied. Compared with HF, HF/n-3 mice showed reduced fat mass, smaller adipocytes in MAT than EAT, improved insulin level, and lower hepatic triacylglycerol and plasma NEFA levels, consistent with liver and brown fat gene expression. Gene expression arrays pointed to immune cell activation in MAT and alleviation of intestinal endothelial cell activation. Validations demonstrated simultaneously upregulated pro- (TNFα, MCP-1) and anti-inflammatory (IL-10) cytokines and M1/M2-macrophage markers in VAT and reduced CD4/CD8α expression in MAT and spleen. Our data revealed differential responsiveness to diets for VAT through preferentially metabolic alterations in MAT and inflammatory processes in EAT. LC-n-3 PUFA effects were pro- and anti-inflammatory and disclose T cell-immunosuppressive potential.

Gluten-free diet reduces adiposity, inflammation and insulin resistance associated with the induction of PPAR-alpha and PPAR-gamma expression

Gluten exclusion (protein complex present in many cereals) has been proposed as an option for the prevention of diseases other than coeliac disease. However, the effects of gluten-free diets on obesity and its mechanisms of action have not been studied. Thus, our objective was to assess whether gluten exclusion can prevent adipose tissue expansion and its consequences. C57BL/6 mice were fed a high-fat diet containing 4.5% gluten (Control) or no gluten (GF). Body weight and adiposity gains, leukocyte rolling and adhesion, macrophage infiltration and cytokine production in adipose tissue were assessed. Blood lipid profiles, glycaemia, insulin resistance and adipokines were measured. Expression of the PPAR-α and γ, lipoprotein lipase (LPL), hormone sensitive lipase (HSL), carnitine palmitoyl acyltransferase-1 (CPT-1), insulin receptor, GLUT-4 and adipokines were assessed in epidydimal fat. Gluten-free animals showed a reduction in body weight gain and adiposity, without changes in food intake or lipid excretion. These results were associated with up-regulation of PPAR-α, LPL, HSL and CPT-1, which are related to lipolysis and fatty acid oxidation. There was an improvement in glucose homeostasis and pro-inflammatory profile-related overexpression of PPAR-γ. Moreover, intravital microscopy showed a lower number of adhered cells in the adipose tissue microvasculature. The overexpression of PPAR-γ is related to the increase of adiponectin and GLUT-4. Our data support the beneficial effects of gluten-free diets in reducing adiposity gain, inflammation and insulin resistance. The data suggests that diet gluten exclusion should be tested as a new dietary approach to prevent the development of obesity and metabolic disorders.

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.

Impact of fat obesity on laparoscopic total mesorectal excision: more reliable indicator than body mass index

BACKGROUND

The aim of this study was to evaluate the impact of visceral fat obesity (VFO) on early surgical and oncologic outcomes of laparoscopic total mesorectal excision (LTME) for rectal cancer.

PATIENTS AND METHODS

Between June 2003 and June 2009, a total of 142 patients who had undergone LTME were included. Patients were divided into the obese group (OG) and the non-obese group (NOG) according to BMI and visceral fat area (VFA). Obesity was defined by BMI ≥25 kg/m² or VFA ≥130 cm².

RESULTS

There were 37 (26.0%) and 29 (20.4%) obese patients according to BMI and VFA, respectively. The OG, defined by both VFA and BMI, had a significantly longer operative time. The VFO group experienced more frequent conversion to laparotomy (17.2% vs. 5.0%; P = 0.047) and significantly higher blood loss during surgery (205.8 ± 257.0 mL vs. 102.5 ± 219.9 mL; P = 0.031), whereas there was no significant difference when defined by BMI. Time to first flatus was significantly longer in the VFO group compared with the NOG (mean 3.5 days vs. 2.7 days; P = 0.046), whereas it was not significantly different when classified by BMI. Regarding oncologic parameters, the VFO group had a significantly higher number of patients from whom less than 12 total lymph nodes were retrieved (65.5% vs. 34.5%; P = 0.002); however, there was no difference between the two groups defined by BMI.

CONCLUSION

VFO is proven to be a more reliable predictive factor than BMI in estimating early surgical outcomes for patients who underwent LTME. VFO is associated with fewer numbers of retrieved lymph nodes.

Leptin deficiency-induced obesity affects the density of mast cells in abdominal fat depots and lymph nodes in mice

Background

Mast cells are implicated in the pathogenesis of obesity and insulin resistance. Here, we explored the effects of leptin deficiency-induced obesity on the density of mast cells in metabolic (abdominal fat depots, skeletal muscle, and liver) and lymphatic (abdominal lymph nodes, spleen, and thymus) organs. Fourteen-week-old male leptin-deficient ob/ob mice and their controls fed a standard chow were studied. Tissue sections were stained with toluidine blue to determine the density of mast cells. CD117/c-kit protein expression analysis was also carried out. Furthermore, mast cells containing immunoreactive tumor necrosis factor-α (TNF-α), a proinflammatory cytokine involved in obesity-linked insulin resistance, were identified by immunostaining.

Results

ob/ob mice demonstrated adiposity and insulin resistance. In abdominal fat depots, mast cells were distributed differentially. While most prevalent in subcutaneous fat in controls, mast cells were most abundant in epididymal fat in ob/ob mice. Leptin deficiency-induced obesity was accompanied by a 20-fold increase in the density of mast cells in epididymal fat, but a 13-fold decrease in subcutaneous fat. This finding was confirmed by CD117/c-kit protein expression analysis. Furthermore, we found that a subset of mast cells in epididymal and subcutaneous fat were immunoreactive for TNF-α. The proportion of mast cells immunoreactive for TNF-α was higher in epididymal than in subcutaneous fat in both ob/ob and control mice. Mast cells were also distributed differentially in retroperitoneal, mesenteric, and inguinal lymph nodes. In both ob/ob mice and lean controls, mast cells were more prevalent in retroperitoneal than in mesenteric and inguinal lymph nodes. Leptin deficiency-induced obesity was accompanied by increased mast cell density in all lymph node stations examined. No significant difference in the density of mast cells in skeletal muscle, liver, spleen, and thymus was noted between ob/ob and control mice.

Conclusions

This study demonstrates that leptin deficiency-induced obesity is accompanied by alterations in the density of mast cells in abdominal fat depots. The divergent distribution of mast cells in subcutaneous versus visceral fat might partially account for their differential biological behavior. Mast cells might also play a role in adaptive immune response occurring in regional lymph nodes in obesity.

Deficiency in interferon-gamma results in reduced body weight and better glucose tolerance in mice

Obesity is a chronic low-grade inflammatory disease caused by increased energy intake and reduced energy expenditure. Studies using animal models with deletion of inflammatory cytokines have produced conflicting results with some showing increased weight gain and others showing no effect or even reduced body weights. Clearly, more work is necessary to understand the role of cytokines on body weight control. The aim of this study was to determine the effect of interferon-γ deletion (IFNγ(-/-)) on body weight regulation and glucose metabolism. Male IFNγ(-/-) and wild-type C57BL/6 mice were fed a low-fat chow diet, and body weight, food intake, and energy expenditure were monitored over 20 wk. At the end of the study, ip glucose tolerance test, insulin tolerance test, basal glucose turnover, and hyperinsulinemic/euglycemic clamps were performed. Expression levels of arcuate nucleus neuropeptide Y, Agouti-related peptide, and proopiomelanocortin mRNA as well as circulating leptin levels were also determined. IFNγ(-/-) mice had improved glucose tolerance with reduced rate of glucose appearance and increased insulin sensitivity due to greater suppression of endogenous glucose output, which was associated with decreased hepatic glucose-6-phosphatase activity. In addition, we also observed reduced body weight associated with decreased food intake and increased physical activity. Neuropeptide Y and Agouti-related peptide mRNA expression was reduced, whereas proopiomelanocortin mRNA expression was increased, as were plasma leptin levels. Global deletion of IFNγ in mice resulted in reduced body weight associated with negative energy balance, improved glucose tolerance, and hepatic insulin sensitivity. Our findings demonstrate that IFNγ plays a critical role in the regulation of body weight and glucose metabolism.

B cell-activating factor controls the production of adipokines and induces insulin resistance

Visceral adipose tissue (VAT) inflammation has been linked to the pathogenesis of insulin resistance and metabolic syndrome. VAT has recently been established as a new component of the immune system and is involved in the production of various adipokines and cytokines. These molecules contribute to inducing and accelerating systemic insulin resistance. In this report, we investigated the role of B cell-activating factor (BAFF) in the induction of insulin resistance. We investigated BAFF levels in the sera and VAT of obese mice. In obese mice, the BAFF levels were preferentially increased in VAT and sera compared to these levels in normal control mice. Next, we treated mice with BAFF to analyze its influence on insulin sensitivity. BAFF impaired insulin sensitivity in normal mice. Finally, we investigated the mechanisms underlying insulin resistance induced by BAFF in adipocytes. BAFF also induced alterations in the expression levels of genes related to insulin resistance in adipocytes. In addition, BAFF directly affected the glucose uptake and phosphorylation of insulin receptor substrate-1 in adipocytes. We propose that autocrine or paracrine BAFF and BAFF-receptor (BAFF-R) interaction in VAT leads to impaired insulin sensitivity via inhibition of insulin signaling pathways and alterations in adipokine production.

Adipose inflammation initiates recruitment of leukocytes to mouse femoral artery: role of adipo-vascular axis in chronic inflammation

Background

Although inflammation within adipose tissues is known to play a role in metabolic syndrome, the causative connection between inflamed adipose tissue and atherosclerosis is not fully understood. In the present study, we examined the direct effects of adipose tissue on macro-vascular inflammation using intravital microscopic analysis of the femoral artery after adipose tissue transplantation.

Methods and Results

We obtained subcutaneous (SQ) and visceral (VIS) adipose tissues from C57BL/6 mice fed normal chow (NC) or a high fat diet (HF), then transplanted the tissues into the perivascular area of the femoral artery of recipient C57/BL6 mice. Quantitative intravital microscopic analysis revealed an increase in adherent leukocytes after adipose tissue transplantation, with VIS found to induce significantly more leukocyte accumulation as compared to SQ. Moreover, adipose tissues from HF fed mice showed significantly more adhesion to the femoral artery. Simultaneous flow cytometry demonstrated upregulation of CD11b on peripheral granulocyte and monocytes after adipose tissue transplantation. We also observed dominant expressions of the inflammatory cytokine IL-6, and chemokines MCP-1 and MIP-1β in the stromal vascular fraction (SVF) of these adipose tissues as well as sera of recipient mice after transplantation. Finally, massive accumulations of pro-inflammatory and dendritic cells were detected in mice with VIS transplantation as compared to SQ, as well as in HF mice as compared to those fed NC.

Conclusion

Our in vivo findings indicate that adipose tissue stimulates leukocyte accumulation in the femoral artery. The underlying mechanisms involve upregulation of CD11b in leukocytes, induction of cytokines and chemokines, and accumulation of pro-inflammatory cells in the SVF.

Novel fat depot-specific mechanisms underlie resistance to visceral obesity and inflammation in 11 β-hydroxysteroid dehydrogenase type 1-deficient mice

OBJECTIVE

The study objective was to determine the key early mechanisms underlying the beneficial redistribution, function, and inflammatory profile of adipose tissue in 11β-hydroxysteroid dehydrogenase type 1 knockout (11β-HSD1(-/-)) mice fed a high-fat (HF) diet.

RESEARCH DESIGN AND METHODS

By focusing on the earliest divergence in visceral adiposity, subcutaneous and visceral fat depots from 11β-HSD1(-/-) and C57Bl/6J control mice fed an HF diet for 4 weeks were used for comparative microarray analysis of gene expression, and differences were validated with real-time PCR. Key changes in metabolic signaling pathways were confirmed using Western blotting/immunoprecipitation, and fat cell size was compared with the respective chow-fed control groups. Altered adipose inflammatory cell content and function after 4 weeks (early) and 18 weeks (chronic) of HF feeding was investigated using fluorescence (and magnetic)-activated cell sorting analysis, immunohistochemistry, and in situ hybridization.

RESULTS

In subcutaneous fat, HF-fed 11β-HSD1(-/-) mice showed evidence of enhanced insulin and β-adrenergic signaling associated with accretion of smaller metabolically active adipocytes. In contrast, reduced 11β-HSD1(-/-) visceral fat accumulation was characterized by maintained AMP kinase activation, not insulin sensitization, and higher adipocyte interleukin-6 release. Intracellular glucocorticoid deficiency was unexpectedly associated with suppressed inflammatory signaling and lower adipocyte monocyte chemoattractant protein-1 secretion with strikingly reduced cytotoxic T-cell and macrophage infiltration, predominantly in visceral fat.

CONCLUSIONS

Our data define for the first time the novel and distinct depot-specific mechanisms driving healthier fat patterning and function as a result of reduced intra-adipose glucocorticoid levels.

Cardiorespiratory fitness and metabolic risk factors in obesity

PURPOSE OF REVIEW

An increase in cardiorespiratory fitness (CRF) through exercise training appears to partly ameliorate the health hazards of obesity and a number of mechanisms might explain the potential benefits. We review recent evidence about the relationships between CRF, exercise training and metabolic risk factors in obesity.

RECENT FINDINGS

Epidemiological data have shown that the anti-inflammatory effects of exercise could be an important mechanism in explaining cardio-protective effects of physical activity. Emerging evidence suggests that exercise training reduces markers of inflammation and improves glucose control in obesity, independent of weight loss. Novel mechanisms appear to involve exercise-induced changes in CD14+CD16+ cell populations, expression of toll-like receptors, and key changes in the metabolic regulation of visceral white adipose tissue. Other promising recent research has focused on exercise-induced signalling pathways governing glucose metabolism, such as insulin receptor substrate and Akt substrate. Using novel imaging techniques, studies have demonstrated exercise-induced improvements in lipoprotein subfraction particle size, and reduction in visceral adipose tissue and liver fat, independent of weight loss. These effects appear to be mostly restricted to interventions consisting of relatively high doses of exercise or exercise combined with calorie restriction, although further work is required to elucidate the dose-response relationships.

SUMMARY

Physical activity and the pursuit of physical fitness are important in the treatment of obesity because exercise training can improve a number of metabolic risk factors independent of weight loss. Thus exercise can provide important health benefits irrespective of weight loss in obese and overweight individuals.

Diet-induced obesity increases NF-kappaB signaling in reporter mice

The nuclear factor (NF)-kappaB is a primary regulator of inflammatory responses and may be linked to pathology associated with obesity. We investigated the progression of NF-kappaB activity during a 12-week feeding period on a high-fat diet (HFD) or a low-fat diet (LFD) using NF-kappaB luciferase reporter mice. In vivo imaging of luciferase activity showed that NF-kappaB activity was higher in the HFD mice compared with LFD-fed mice. Thorax region of HFD females displayed fourfold higher activity compared with LFD females, while no such increase was evident in males. In male HFD mice, abdominal NF-kappaB activity was increased twofold compared with the LFD males, while females had unchanged NF-kappaB activity in the abdomen by HFD. HFD males, but not females, exhibited evident glucose intolerance during the study. In conclusion, HFD increased NF-kappaB activity in both female and male mice. However, HFD differentially increased activity in males and females. The moderate increase in abdomen of male mice may be linked to glucose intolerance.