Loss of Oncostatin M Signaling in Adipocytes Induces Insulin Resistance and Adipose Tissue Inflammation in Vivo.

Oncostatin M (OSM) is a multifunctional gp130 cytokine. Although OSM is produced in adipose tissue, it is not produced by adipocytes. OSM expression is significantly induced in adipose tissue from obese mice and humans. The OSM-specific receptor, OSM receptor ß (OSMR), is expressed in adipocytes, but its function remains largely unknown. To better understand the effects of OSM in adipose tissue, we knocked down Osmr expression in adipocytes in vitro using siRNA. In vivo, we generated a mouse line lacking Osmr in adiponectin-expressing cells (OSMR(FKO) mice). The effects of OSM on gene expression were also assessed in vitro and in vivo OSM exerts proinflammatory effects on cultured adipocytes that are partially rescued by Osmr knockdown. Osm expression is significantly increased in adipose tissue T cells of high fat-fed mice. In addition, adipocyte Osmr expression is increased following high fat feeding. OSMR(FKO) mice exhibit increased insulin resistance and adipose tissue inflammation and have increased lean mass, femoral length, and bone volume. Also, OSMR(FKO) mice exhibit increased expression of Osm, the T cell markers Cd4 and Cd8, and the macrophage markers F4/80 and Cd11c Interestingly, the same proinflammatory genes induced by OSM in adipocytes are induced in the adipose tissue of the OSMR(FKO) mouse, suggesting that increased expression of proinflammatory genes in adipose tissue arises both from adipocytes and other cell types. These findings suggest that adipocyte OSMR signaling is involved in the regulation of adipose tissue homeostasis and that, in obesity, OSMR ablation may exacerbate insulin resistance by promoting adipose tissue inflammation.

CCL20 is elevated during obesity and differentially regulated by NF-κB subunits in pancreatic ß-cells.

Enhanced leukocytic infiltration into pancreatic islets contributes to inflammation-based diminutions in functional ß-cell mass. Insulitis (aka islet inflammation), which can be present in both T1DM and T2DM, is one factor influencing pancreatic ß-cell death and dysfunction. IL-1ß, an inflammatory mediator in both T1DM and T2DM, acutely (within 1h) induced expression of the CCL20 gene in rat and human islets and clonal ß-cell lines. Transcriptional induction of CCL20 required the p65 subunit of NF-κB to replace the p50 subunit at two functional κB sites within the CCL20 proximal gene promoter. The NF-κB p50 subunit prevents CCL20 gene expression during unstimulated conditions and overexpression of p50 reduces CCL20, but enhances cyclooxygenase-2 (COX-2), transcript accumulation after exposure to IL-1ß. We also identified differential recruitment of specific co-activator molecules to the CCL20 gene promoter, when compared with the CCL2 and COX2 genes, revealing distinct transcriptional requirements for individual NF-κB responsive genes. Moreover, IL-1ß, TNF-α and IFN-γ individually increased the expression of CCR6, the receptor for CCL20, on the surface of human neutrophils. We further found that the chemokine CCL20 is elevated in serum from both genetically obese db/db mice and in C57BL6/J mice fed a high-fat diet. Taken together, these results are consistent with a possible activation of the CCL20-CCR6 axis in diseases with inflammatory components. Thus, interfering with this signaling pathway, either at the level of NF-κB-mediated chemokine production, or downstream receptor activation, could be a potential therapeutic target to offset inflammation-associated tissue dysfunction in obesity and diabetes.

Fat in flames: influence of cytokines and pattern recognition receptors on adipocyte lipolysis.

Adipose tissue has the largest capacity to store energy in the body and provides energy through the release of free fatty acids during times of energy need. Different types of immune cells are recruited to adipose tissue under various physiological conditions, indicating that these cells contribute to the regulation of adipose tissue. One major pathway influenced by a number of immune cells is the release of free fatty acids through lipolysis during both physiological (e.g., cold stress) and pathophysiological processes (e.g., obesity, type 2 diabetes). Adipose tissue expansion during obesity leads to immune cell infiltration and adipose tissue remodeling, a homeostatic process that promotes inflammation in adipose tissue. The release of proinflammatory cytokines stimulates lipolysis and causes insulin resistance, leading to adipose tissue dysfunction and systemic disruptions of metabolism. This review focuses on the interactions of cytokines and other inflammatory molecules that regulate adipose tissue lipolysis during physiological and pathophysiological states.

A Randomized, Double-Blind, Crossover Study to Investigate the Pharmacokinetics of Extended-Release Melatonin Compared to Immediate-Release Melatonin in Healthy Adults.

Exogenous melatonin can be helpful for treatment of some sleep disorders. However, immediate-release formulations are rapidly absorbed and cleared from the body making it difficult to provide coverage for an entire sleep period. Extended-release melatonin formulations can better mimic the naturally occurring melatonin profile and increase efficacy, but few studies have reported on their pharmacokinetics. To assess the pharmacokinetics of extended-release melatonin, we conducted a randomized, double-blind, crossover study of extended-release melatonin (4 mg) compared to immediate-release melatonin (4 mg) in 18 healthy adults, ages 18-65 years. Participants received immediate-release or extended-release melatonin in clinic after an 8 h fast, and blood samples were taken over a 10-h period. After a 7-day washout period, the same procedures were repeated with the melatonin form not previously received. Extended-release melatonin had a longer time to peak concentration (1.56 vs 0.6 h) and elimination half-life (1.63 vs 0.95 h) compared with immediate-release melatonin. Maximum concentration was lower for extended-release melatonin compared with immediate-release melatonin (7581 pg/mL vs 13120 pg/mL). Extended-release melatonin raised melatonin levels in as little as 15 min and sustained elevated melatonin levels (>300 pg/mL) for 6 h before falling below 50 pg/mL by 9 h. No clinically relevant adverse events were observed, and safety parameters remained within normal ranges for both formulations. The pharmacokinetic profile of this extended-release melatonin formulation suggests that it could be used for future efficacy studies of melatonin and sleep outcomes. This trial is registered at ClinicalTrials.gov, NCT04067791.

Subcutaneous and gonadal adipose tissue transcriptome differences in lean and obese female dogs.

Canine obesity leads to shortened life span and increased disease incidence. Adipose tissue depots are known to have unique metabolic and gene expression profiles in rodents and humans, but few comparisons of depot gene expression have been performed in the dog. Using microarray technology, our objective was to identify differentially expressed genes and enriched functional pathways between subcutaneous and gonadal adipose of lean and obese dogs to better understand the pathogenesis of obesity in the dog. Because no depot × body weight status interactions were identified in the microarray data, depot differences were the primary focus. A total of 946 and 703 transcripts were differentially expressed (FDR P < 0.05) between gonadal and subcutaneous adipose tissue in obese and lean dogs respectively. Of the adipose depot-specific differences in gene expression, 162 were present in both lean and obese dogs, with the majority (85%) expressed in the same direction. Both lean and obese dog gene lists had enrichment of the complement and coagulation cascade and systemic lupus erythematosus pathways. Obese dogs had enrichment of lysosome, extracellular matrix-receptor interaction, renin-angiotensin system and hematopoietic cell lineage pathways. Lean dogs had enrichment of glutathione metabolism and synthesis and degradation of ketone bodies. We have identified a core set of genes differentially expressed between subcutaneous and gonadal adipose tissue in dogs regardless of body weight. These genes contribute to depot-specific differences in immune function, extracellular matrix remodeling and lysosomal function and may contribute to the physiological differences noted between depots.

Higher intake of certain nutrients among older adults is associated with better cognitive function: an analysis of NHANES 2011-2014.

BACKGROUND: An increasing number of adults are over the age of 65, and there is concern about the increasing prevalence of age-associated cognitive decline and poor mental health status in older adults in the United States. Several nutrients are known to have important biological roles in brain health and neurological function, but many individuals fall short of recommended intake levels. The objective of this study was to examine the association between nutrient intake and cognitive function. We also explored whether nutrient intake was associated with depression. METHODS: This cross-sectional study was based on data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 and included participants ≥ 60 years of age who had reliable day 1 dietary recall data and either valid cognitive function data (n = 2713) or valid depression score data (n = 2943). The sample was stratified by gender, and cognitive functioning test (CFT) composite z-scores were analyzed by quartiles. Depression status was assessed using the Patient Health Questionnaire (PHQ-9). RESULTS: Higher intake and adequacy of a number of different nutrients from food were associated with higher cognitive function in both males and females. Nutrients that showed the most consistent associations with cognitive function across intake and adequacy analyses for food in both males and females were vitamin A, vitamin E, thiamin, riboflavin, vitamin B6, folate, magnesium, potassium, zinc, vitamin K, and lutein and zeaxanthin (p < 0.05 for all). These associations were positive with increasing intake and adequacy being associated with higher CFT composite z-scores. Analysis of nutrient intake and depression yielded results that differed by gender. In females, the nutrients that showed consistent inverse associations with depression scores across both intake and adequacy analyses for food were vitamin A, vitamin C, magnesium, vitamin K, potassium, and dietary fiber (p < 0.05 for all). In males, no significant associations between nutrient intake from food and depression scores were observed. CONCLUSIONS: Our findings suggest that older adults with sufficient intakes of certain essential nutrients have higher cognitive function. Future studies are needed to confirm whether a well-balanced diet and/or dietary supplements which emphasize these nutrients are effective for prevention of age-related declines in cognitive function and mood.

Lower Intakes of Key Nutrients Are Associated with More School and Workplace Absenteeism in US Children and Adults: A Cross-Sectional Study of NHANES 2003-2008.

The influence of individual macro- and micronutrients on absenteeism in the United States is largely unknown. The objective of this study was to determine whether nutritional status or nutrient intake were associated with absenteeism from school and work due to illness or injury. Data from NHANES 2003-2008 were used to assess nutrient intake from food and food plus supplements, nutritional biomarker levels, and school and work absenteeism per year in children and adults. Negative binomial regression models were used to predict mean days of missed work per year and to estimate incidence rate ratios (IRRs) of absenteeism by nutrient biomarker status. Of 7429 children, 77% reported missing school days (mean 4.0 days). Of 8252 adults, 51% reported missing work days (mean 4.9 days). Children and adults who reported more absent days had a significantly lower intake of protein and several essential micronutrients from the diet. When nutrients from supplements were included, this negative association was retained for protein, selenium, choline, and DHA in children and for protein, selenium, vitamin K, choline, potassium, fiber, octadecatrienoic acid, and lycopene in adults. Future studies are needed to ascertain whether dietary interventions, such as access to healthier food options and/or dietary supplements, can reduce absenteeism.

Adipose tissue transcriptome changes during obesity development in female dogs.

During the development of obesity, adipose tissue undergoes major expansion and remodeling, but the biological processes involved in this transition are not well understood. The objective of this study was to analyze global gene expression profiles of adipose tissue in dogs, fed a high-fat diet, during the transition from a lean to obese phenotype. Nine female beagles (4.09 ± 0.64 yr; 8.48 ± 0.35 kg) were randomized to ad libitum feeding or body weight maintenance. Subcutaneous adipose tissue biopsy, blood, and dual x-ray absorptiometry measurements were collected at 0, 4, 8, 12, and 24 wk of feeding. Serum was analyzed for glucose, insulin, fructosamine, triglycerides, free fatty acids, adiponectin, and leptin. Formalin-fixed adipose tissue was used for determination of adipocyte size. Adipose RNA samples were hybridized to Affymetrix Canine 2.0 microarrays. Statistical analysis, using repeated-measures ANOVA, showed ad libitum feeding increased (P < 0.05) body weight (0 wk, 8.36 ± 0.34 kg; 24 wk, 14.64 ± 0.34 kg), body fat mass (0 wk, 1.36 ± 0.24 kg; 24 wk, 6.52 ± 0.24 kg), adipocyte size (0 wk, 114.66 ± 17.38 µm(2); 24 wk, 320.97 ± 0.18.17 µm(2)), and leptin (0 wk, 0.8 ± 1.0 ng/ml; 24 wk, 12.9 ± 1.0 ng/ml). Microarrays displayed 1,665 differentially expressed genes in adipose tissue as weight increased. Alterations were seen in adipose tissue homeostatic processes including metabolism, oxidative stress, mitochondrial homeostasis, and extracellular matrix. Adipose transcriptome changes highlight the dynamic and adaptive response to ad libitum feeding and obesity development.

Physical activity level of adult cats with varied feeding frequency.

The prevalence of feline obesity is influenced by numerous factors, including inactivity and overconsumption of food. The objective of the present study was to evaluate the effect of feeding frequency on physical activity in adult cats. A total of twelve healthy adult cats were used in a cross-over study consisting of 32 d. In each of the two periods, six cats were fed either two meals or four meals daily. Throughout the study, cats were fed the same diet at amounts to maintain body weight and body condition score. Cats were individually housed 4 h/d at each scheduled feeding time, while for the other 20 h, cats were group-housed to allow for voluntary physical activity in the room with a 16 h light-8 h dark cycle. Voluntary activity levels were evaluated using Actical activity collars for seven consecutive days in each period. Daily average activity level for two-meal-fed cats (20.04 (SEM 2.19), activity counts/epoch (15 s)) was not different from four-meal-fed cats (20.14 (SEM 2.15), activity counts/epoch (15 s); P>0.05). In conclusion, when group-housed cats are fed to maintain their body weight and body condition score, varied feeding frequency between twice and four times daily may not affect activity levels.

Total estimated usual nutrient intake and nutrient status biomarkers in women of childbearing age and women of menopausal age.

BACKGROUND: Women of childbearing age (WCBA) and women of menopausal age (WMENO) have distinct nutritional needs. Understanding nutrient intake and status in these life stages is critical for tailoring dietary recommendations. OBJECTIVES: The objectives of this study were to evaluate total estimated usual nutrient intakes from food and food plus supplements and to compare these to established recommendations for WCBA and WMENO life stages and examine associations between self-reported estimated usual intakes and nutrient status biomarkers. METHODS: Twenty-four-hour dietary recall data from 2011-2016 NHANES were used to estimate usual intake of nutrients from food and food plus supplements for WCBA (aged 15-44 y, n = 4,134) and WMENO (aged 40-65 y, n = 3,438). Estimates of mean usual intake were derived and compared across clinically defined nutrient biomarker categories. RESULTS: Both young (aged 15-30 y) and older (aged 31-44 y) WCBA had intakes from food below the Estimated Average Requirement (EAR) for calcium (49% and 44%, respectively), magnesium (62%, 44%), and vitamins A (50%, 44%), C (47%, 46%), D (>97%, >97%), and E (92%, 88%). Similarly, perimenopausal (aged 40-50 y) and menopausal (aged 51-65 y) women had intakes from food below the EAR for calcium (48% and 74%, respectively), magnesium (50%, 49%), and vitamins A (44%, 37%), C (44%, 41%), D (>97%, >97%), and E (88%, 86%). Nutrient gaps decreased with supplement usage. For folate, vitamins D and B-12, and DHA, women in the lowest biomarker category (indicating increased risk of deficiency) had significantly lower intake from food (315.2 ± 25.9 compared with 463.8 ± 5.2 µg dietary folate equivalents, 3.5 ± 0.1 compared with 4.2 ± 0.1 µg, 3.6 ± 0.2 compared with 4.3 ± 0.1 µg, and 0.037 ± 0.005 compared with 0.070 ± 0.006 g, respectively; P < 0.01) of the corresponding nutrient compared with the highest biomarker category. CONCLUSIONS: Substantial percentages of WCBA and WMENO are not meeting recommendations for multiple nutrients, whereas supplement usage partially fills nutrient gaps. Dietary intake was positively associated with most nutrient status biomarkers. Specific guidance is needed to ensure adequate nutrient intakes and nutrient status during these critical life stages.

Inadequacy of Immune Health Nutrients: Intakes in US Adults, the 2005-2016 NHANES.

A well-functioning immune system is essential for human health and well-being. Micronutrients such as vitamins A, C, D, E, and zinc have several functions throughout the immune system, yet inadequate nutrient intakes are pervasive in the US population. A large body of research shows that nutrient inadequacies can impair immune function and weaken the immune response. Here, we present a new analysis of micronutrient usual intake estimates based on nationally representative data in 26,282 adults (>19 years) from the 2005-2016 National Health and Nutrition Examination Surveys (NHANES). Overall, the prevalence of inadequacy (% of population below estimated average requirement [EAR]) in four out of five key immune nutrients is substantial. Specifically, 45% of the U.S. population had a prevalence of inadequacy for vitamin A, 46% for vitamin C, 95% for vitamin D, 84% for vitamin E, and 15% for zinc. Dietary supplements can help address nutrient inadequacy for these immune-support nutrients, demonstrated by a lower prevalence of individuals below the EAR. Given the long-term presence and widening of nutrient gaps in the U.S.-specifically in critical nutrients that support immune health-public health measures should adopt guidelines to ensure an adequate intake of these micronutrients. Future research is needed to better understand the interactions and complexities of multiple nutrient shortfalls on immune health and assess and identify optimal levels of intake in at-risk populations.

Maternal Omega-3 Nutrition, Placental Transfer and Fetal Brain Development in Gestational Diabetes and Preeclampsia.

Omega-3 fatty acids, particularly docosahexaenoic fatty acid (DHA), are widely recognized to impact fetal and infant neurodevelopment. The impact of DHA on brain development, and its inefficient synthesis from the essential alpha-linolenic acid (ALA), has led to recommended DHA intakes of 250-375 mg eicosapentaenoic acid + DHA/day for pregnant and lactating women by the Dietary Guidelines for Americans. Despite these recommendations, the intake of omega-3s in women of child-bearing age in the US remains very low. The low maternal status of DHA prior to pregnancy could impair fetal neurodevelopment. This review focuses on maternal omega-3 status in conditions of gestational diabetes mellitus (GDM) and preeclampsia, and the subsequent impact on placental transfer and cord blood concentration of omega-3s. Both GDM and preeclampsia are associated with altered maternal omega-3 status, altered placental omega-3 metabolism, reduced cord blood omega-3 levels and have an impact on neurodevelopment in the infant and on brain health later in life. These findings indicate lower DHA exposure of the developing baby may be driven by lower placental transfer in both conditions. Thus, determining approaches which facilitate increased delivery of DHA during pregnancy and early development might positively impact brain development in infants born to mothers with these diseases.

Micronutrient Inadequacy in Short Sleep: Analysis of the NHANES 2005-2016.

One third of U.S. adults report short sleep (<7 h), which has been linked to negative health outcomes. Inadequate intake of micronutrients across the U.S. adult population has been reported, and a relationship between sleep conditions and micronutrient intake is emerging. This cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES 2005-2016) (n = 26,211) showed that participants with short sleep duration had a lower usual intake (Food + Supplements) of calcium, magnesium, and vitamin D in all adults aged 19+ years, and vitamin K in adults aged 19-50 years, even after adjusting for covariates. In addition, participants reporting short sleep had a higher percentage of individuals with intake lower than the estimated average requirement (EAR) across multiple nutrients. Age and gender differences were observed in the prevalence of inadequate intake across multiple nutrients. Adults aged 51-99 years with short sleep duration had inadequate intake with respect to more nutrients. In females there was an association between short sleep and a higher prevalence of inadequate intake (Food + Spp) for calcium, magnesium, and vitamins A, C, D, E, and K (above adequate intake). Conversely, males reporting short sleep only had an inadequate intake of vitamin D. Overall, we demonstrate that short sleep is associated with increased nutrient inadequacy, emphasizing the possible need for dietary supplementation.

Proteomic Analysis of 3T3-L1 Adipocytes Treated with Insulin and TNF-α.

Insulin resistance is an indication of early stage Type 2 diabetes (T2D). Insulin resistant adipose tissues contain higher levels of insulin than the physiological level, as well as higher amounts of intracellular tumor necrosis factor-α (TNF-α) and other cytokines. However, the mechanism of insulin resistance remains poorly understood. To better understand the roles played by insulin and TNF-α in insulin resistance, we performed proteomic analysis of differentiated 3T3-L1 adipocytes treated with insulin (Ins), TNF-α (TNF), and both (Ins + TNF). Out of the 693 proteins identified, the abundances of 78 proteins were significantly different (p < 0.05). Carnitine parmitoyltransferase-2 (CPT2), acetyl CoA carboxylase 1 (ACCAC-1), ethylmalonyl CoA decarboxylase (ECHD1), and methylmalonyl CoA isomerase (MCEE), enzymes required for fatty acid ß-oxidation and respiratory electron transport, and ß-glucuronidase, an enzyme responsible for the breakdown of complex carbohydrates, were down-regulated in all the treatment groups, compared to the control group. In contrast, superoxide dismutase 2 (SOD2), protein disulfide isomerase (PDI), and glutathione reductase, which are the proteins responsible for cytoskeletal structure, protein folding, degradation, and oxidative stress responses, were up-regulated. This suggests higher oxidative stress in cells treated with Ins, TNF, or both. We proposed a conceptual metabolic pathway impacted by the treatments and their possible link to insulin resistance or T2D.

Metabolic and endocrine profiles in response to systemic infusion of fructose and glucose in rhesus macaques.

Diurnal patterns of circulating leptin concentrations are attenuated after consumption of fructose-sweetened beverages compared with glucose-sweetened beverages, likely a result of limited postprandial glucose and insulin excursions after fructose. Differences in postprandial exposure of adipose tissue to peripheral circulating fructose and glucose or in adipocyte metabolism of the two sugars may also be involved. Thus, we compared plasma leptin concentrations after 6-h iv infusions of saline, glucose, or fructose (15 mg/kg.min) in overnight-fasted adult rhesus monkeys (n = 9). Despite increases of plasma fructose from undetectable levels to about 2 mm during fructose infusion, plasma leptin concentrations did not increase, and the change of insulin was only about 10% of that seen during glucose infusion. During glucose infusion, plasma leptin was significantly increased above baseline concentrations by 240 min and increased steadily until the final 480-min time point (change in leptin = +2.5 +/- 0.9 ng/ml, P < 0.001 vs. saline; percent change in leptin = +55 +/- 16%; P < 0.005 vs. saline). Substantial anaerobic metabolism of fructose was suggested by a large increase of steady-state plasma lactate (change in lactate = 1.64 +/- 0.15 mm from baseline), which was significantly greater than that during glucose (+0.53 +/- 0.14 mm) or saline (-0.51 +/- 0.14 mm) infusions (P < 0.001). Therefore, increased adipose exposure to fructose and an active whole-body anaerobic fructose metabolism are not sufficient to increase circulating leptin levels in rhesus monkeys. Thus, additional factors (i.e. limited post-fructose insulin excursions and/or hexose-specific differences in adipocyte metabolism) are likely to underlie disparate effects of fructose and glucose to increase circulating leptin concentrations.

Long-Term Effects of Dietary Protein and Branched-Chain Amino Acids on Metabolism and Inflammation in Mice.

Aging is the main factor involved in the onset of degenerative diseases. Dietary protein restriction has been shown to increase the lifespan of rodents and improve metabolic phenotype. Branched-chain amino acids (BCAA) can act as nutrient signals that increase the lifespan of mice after prolonged supplementation. It remains unclear whether the combination of protein restriction and BCAA supplementation improves metabolic and immunological profiles during aging. Here, we investigated how dietary protein levels and BCAA supplementation impact metabolism and immune profile during a 12-month intervention in adult male C57BL/6J mice. We found that protein restriction improved insulin tolerance and increased hepatic fibroblast growth factor 21 mRNA, circulating interleukin (IL)-5 concentration, and thermogenic uncoupling protein 1 in subcutaneous white fat. Surprisingly, BCAA supplementation conditionally increased body weight, lean mass, and fat mass, and deteriorated insulin intolerance during protein restriction, but not during protein sufficiency. BCAA also induced pro-inflammatory gene expression in visceral adipose tissue under both normal and low protein conditions. These results suggest that dietary protein levels and BCAA supplementation coordinate a complex regulation of metabolism and tissue inflammation during prolonged feeding.

2-deoxyglucose inhibits induction of chemokine expression in 3T3-L1 adipocytes and adipose tissue explants.

OBJECTIVE: To determine the influence of glycolytic inhibition on the adipocyte inflammatory response. METHODS: To determine the effect of 2-deoxyglucose (2-DOG) on the inflammatory response, mature 3T3-L1 adipocytes were co-treated with 2-DOG and LPS or TNF. To determine the effect of endoplasmic reticulum stress on TNF-induced induction of chemokines, adipocytes were pretreated with thapsigargin or salubrinal. Chemokine mRNA levels were determined using quantitative real-time PCR, and secretion of CCL2 was determined by Western blot. RESULTS: 2-DOG treatment reduced the ability of LPS and TNF to induce CCL2 mRNA levels and reduced secreted CCL2 protein levels in a dose-dependent manner. A similar pattern of mRNA regulation was observed for other chemokines. The attenuation of TNF-induced CCL2 mRNA levels occurred regardless of whether glucose or pyruvate was present in the media, suggesting that mechanisms other than glycolysis might mediate the observed effects. Treatment with the endoplasmic reticulum stressor thapsigargin and the endoplasmic reticulum signaling activator salubrinal reduced chemokine mRNA levels similarly to 2-DOG. CONCLUSIONS: Collectively, our data indicate that 2-DOG suppresses inflammatory chemokine induction in adipocytes. The effects of 2-DOG do not seem to be linked to glycolysis but correlate with endoplasmic reticulum stress activation.

Loss of Nlrp3 Does Not Protect Mice from Western Diet-Induced Adipose Tissue Inflammation and Glucose Intolerance.

We tested the hypothesis that loss of Nlrp3 would protect mice from Western diet-induced adipose tissue (AT) inflammation and associated glucose intolerance and cardiovascular complications. Five-week old C57BL6J wild-type (WT) and Nlrp3 knockout (Nlrp3-/-) mice were randomized to either a control diet (10% kcal from fat) or Western diet (45% kcal from fat and 1% cholesterol) for 24 weeks (n = 8/group). Contrary to our hypothesis that obesity-mediated white AT inflammation is Nlrp3-dependent, we found that Western diet-induced expression of AT inflammatory markers (i.e., Cd68, Cd11c, Emr1, Itgam, Lgals, Il18, Mcp1, Tnf, Ccr2, Ccl5 mRNAs, and Mac-2 protein) were not accompanied by increased caspase-1 cleavage, a hallmark feature of NLRP3 inflammasome activation. Furthermore, Nlrp3 null mice were not protected from Western diet-induced white or brown AT inflammation. Although Western diet promoted glucose intolerance in both WT and Nlrp3-/- mice, Nlrp3-/- mice were protected from Western diet-induced aortic stiffening. Additionally, Nlrp3-/- mice exhibited smaller cardiomyocytes and reduced cardiac fibrosis, independent of diet. Collectively, these findings suggest that presence of the Nlrp3 gene is not required for Western diet-induced AT inflammation and/or glucose intolerance; yet Nlrp3 appears to play a role in potentiating arterial stiffening, cardiac hypertrophy and fibrosis.

Adipose tissue as an immunological organ.

OBJECTIVE: This review will focus on the immunological aspects of adipose tissue and its potential role in development of chronic inflammation that instigates obesity-associated comorbidities. METHODS: The review used PubMed searches of current literature to examine adipose tissue leukocytosis. RESULTS AND CONCLUSIONS: The adipose tissue of obese subjects becomes inflamed and contributes to the development of insulin resistance, type 2 diabetes, and metabolic syndrome. Numerous immune cells including B cells, T cells, macrophages, and neutrophils have been identified in adipose tissue, and obesity influences both the quantity and the nature of immune cell subtypes, which emerges as an active immunological organ capable of modifying whole-body metabolism through paracrine and endocrine mechanisms. Adipose tissue is a large immunologically active organ during obesity and displays hallmarks of both and innate and adaptive immune response. Despite the presence of hematopoietic lineage cells in adipose tissue, it is unclear whether the adipose compartment has a direct role in immune surveillance or host defense. Understanding the interactions between leukocytes and adipocytes may reveal the clinically relevant pathways that control adipose tissue inflammation and is likely to reveal mechanisms by which obesity contributes to increased susceptibility to both metabolic and certain infectious diseases.

The ketone metabolite ß-hydroxybutyrate blocks NLRP3 inflammasome-mediated inflammatory disease.

The ketone bodies ß-hydroxybutyrate (BHB) and acetoacetate (AcAc) support mammalian survival during states of energy deficit by serving as alternative sources of ATP. BHB levels are elevated by starvation, caloric restriction, high-intensity exercise, or the low-carbohydrate ketogenic diet. Prolonged fasting reduces inflammation; however, the impact that ketones and other alternative metabolic fuels produced during energy deficits have on the innate immune response is unknown. We report that BHB, but neither AcAc nor the structurally related short-chain fatty acids butyrate and acetate, suppresses activation of the NLRP3 inflammasome in response to urate crystals, ATP and lipotoxic fatty acids. BHB did not inhibit caspase-1 activation in response to pathogens that activate the NLR family, CARD domain containing 4 (NLRC4) or absent in melanoma 2 (AIM2) inflammasome and did not affect non-canonical caspase-11, inflammasome activation. Mechanistically, BHB inhibits the NLRP3 inflammasome by preventing K(+) efflux and reducing ASC oligomerization and speck formation. The inhibitory effects of BHB on NLRP3 are not dependent on chirality or starvation-regulated mechanisms like AMP-activated protein kinase (AMPK), reactive oxygen species (ROS), autophagy or glycolytic inhibition. BHB blocks the NLRP3 inflammasome without undergoing oxidation in the TCA cycle, and independently of uncoupling protein-2 (UCP2), sirtuin-2 (SIRT2), the G protein-coupled receptor GPR109A or hydrocaboxylic acid receptor 2 (HCAR2). BHB reduces NLRP3 inflammasome-mediated interleukin (IL)-1ß and IL-18 production in human monocytes. In vivo, BHB or a ketogenic diet attenuates caspase-1 activation and IL-1ß secretion in mouse models of NLRP3-mediated diseases such as Muckle-Wells syndrome, familial cold autoinflammatory syndrome and urate crystal-induced peritonitis. Our findings suggest that the anti-inflammatory effects of caloric restriction or ketogenic diets may be linked to BHB-mediated inhibition of the NLRP3 inflammasome.