Interferons and tumor necrosis factors have similar catabolic effects on 3T3 L1 cells

Intracellular infection and immune system cues rewire adipocytes to acquire immune function

Adipose tissue (AT) plays a central role in systemic metabolic homeostasis, but its function during bacterial infection remains unclear. Following subcutaneous bacterial infection, adipocytes surrounding draining lymph nodes initiated a transcriptional response indicative of stimulation with IFN-γ and a shift away from lipid metabolism toward an immunologic function. Natural killer (NK) and invariant NK T (iNKT) cells were identified as sources of infection-induced IFN-γ in perinodal AT (PAT). IFN-γ induced Nos2 expression in adipocytes through a process dependent on nuclear-binding oligomerization domain 1 (NOD1) sensing of live intracellular bacteria. iNOS expression was coupled to metabolic rewiring, inducing increased diversion of extracellular L-arginine through the arginosuccinate shunt and urea cycle to produce nitric oxide (NO), directly mediating bacterial clearance. In vivo, control of infection in adipocytes was dependent on adipocyte-intrinsic sensing of IFN-γ and expression of iNOS. Thus, adipocytes are licensed by innate lymphocytes to acquire anti-bacterial functions during infection.

Association between Hypertriglyceridemia and Disease Severity in Visceral Leishmaniasis

Visceral leishmaniasis (VL) is a tropical disease endemic to Brazil. The clinical manifestations of the infection range from asymptomatic to severe. In VL, changes in lipid metabolism, such as hypocholesterolemia and hypertriglyceridemia, occur that are believed to be related to its progression and severity. This study investigated the associations between serum levels of cholesterol, triglycerides, and lipoproteins (high-density lipoprotein, low-density lipoprotein, and very low-density lipoprotein) with clinical and hematological parameters that predict severity in a case series of 83 VL patients. Severely ill patients had higher mean serum triglyceride levels than non-severely ill patients. There was a significant positive correlation between disease severity score and serum triglyceride levels, very low-density lipoprotein, international normalized ratio for prothrombin time test, total bilirubin, and age. An inverse correlation was detected between the disease severity score and mean platelet and neutrophil counts. Hypertriglyceridemia can be a prognostic indicator of severity in patients diagnosed with VL.

Interferon-γ Impairs Human Coronary Artery Endothelial Glucose Metabolism by Tryptophan Catabolism and Activates Fatty Acid Oxidation

BACKGROUND

Endothelial cells depend on glycolysis for much of their energy production. Impaired endothelial glycolysis has been associated with various vascular pathobiologies, including impaired angiogenesis and atherogenesis. IFN-γ (interferon-γ)-producing CD4⁺ and CD8⁺ T lymphocytes have been identified as the predominant pathological cell subsets in human atherosclerotic plaques. Although the immunologic consequences of these cells have been extensively evaluated, their IFN-γ-mediated metabolic effects on endothelial cells remain unknown. The purpose of this study was to determine the metabolic consequences of the T-lymphocyte cytokine, IFN-γ, on human coronary artery endothelial cells.

METHODS

The metabolic effects of IFN-γ on primary human coronary artery endothelial cells were assessed by unbiased transcriptomic and metabolomic analyses combined with real-time extracellular flux analyses and molecular mechanistic studies. Cellular phenotypic correlations were made by measuring altered endothelial intracellular cGMP content, wound-healing capacity, and adhesion molecule expression.

RESULTS

IFN-γ exposure inhibited basal glycolysis of quiescent primary human coronary artery endothelial cells by 20% through the global transcriptional suppression of glycolytic enzymes resulting from decreased basal HIF1α (hypoxia-inducible factor 1α) nuclear availability in normoxia. The decrease in HIF1α activity was a consequence of IFN-γ-induced tryptophan catabolism resulting in ARNT (aryl hydrocarbon receptor nuclear translocator)/HIF1β sequestration by the kynurenine-activated AHR (aryl hydrocarbon receptor). In addition, IFN-γ resulted in a 23% depletion of intracellular nicotinamide adenine dinucleotide in human coronary artery endothelial cells. This altered glucose metabolism was met with concomitant activation of fatty acid oxidation, which augmented its contribution to intracellular ATP balance by >20%. These metabolic derangements were associated with adverse endothelial phenotypic changes, including decreased basal intracellular cGMP, impaired endothelial migration, and a switch to a proinflammatory state.

CONCLUSIONS

IFN-γ impairs endothelial glucose metabolism by altered tryptophan catabolism destabilizing HIF1, depletes nicotinamide adenine dinucleotide, and results in a metabolic shift toward increased fatty acid oxidation. This work suggests a novel mechanistic basis for pathological T lymphocyte-endothelial interactions in atherosclerosis mediated by IFN-γ, linking endothelial glucose, tryptophan, and fatty acid metabolism with the nicotinamide adenine dinucleotide balance and ATP generation and their adverse endothelial functional consequences.

Association between dietary inflammatory potential and risk of developing gestational diabetes: a prospective cohort study

Background

Limited and inconsistent data are available regarding the relationship between the dietary inflammatory potential (DIP) and risk of gestational diabetes mellitus (GDM).

Objective

The present prospective study aimed to evaluate the association between DIP score during the first trimester of pregnancy and risk of developing GDM among Iranian women.

Methods

In this prospective cohort study, 812 pregnant women aged 20–40 years, who were in their first trimester, were recruited and followed up until week 24–28 of gestation. Dietary intakes of study subjects were examined using an interviewer-administered validated 117-item semi-quantitative food frequency questionnaire (FFQ). DIP score was calculated from 29 available food parameters based on earlier literature. The results of a fasting plasma glucose concentration and a 50-g, 1-h oral glucose tolerance test, between the 24th and 28th week of gestation, were used to diagnose GDM. The risk of developing GDM across quartiles of DIP score was estimated using Cox regression in several models.

Results

At study baseline, mean (SD) age and BMI of study participants were 29.4 (±4.84) y and 25.14 (±4.08) kg/m², respectively. No significant association was found between DIP score and risk of GDM in the crude model (RR: 1.01; 95% CIs: 0.71–1.45). When we adjusted for age the association did not alter (RR: 1.04; 95% CIs: 0.72–1.48). Even after further adjustment for maternal weight gain we failed to find a significant association between DIP score and risk of GDM (RR: 0.97; 95% CIs: 0.66–1.41).

Conclusion

We found no significant association between DIP and risk of developing GDM. Further longitudinal studies among other populations are needed to elucidate the association between DIP score and GDM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-021-00705-5.

Hypertriglyceridemia during Long-Term Interferon-Alpha Therapy: Efficacy of Diet and Gemfibrosil Treatment. A Case Report

Interferon-alpha might increase triglyceride serum levels through the enhancement of hepatic lipogenesis and/or inhibition of the peripheral lipoprotein lipase. Hypertriglyceridemia during interferon-alpha therapy has been only recently described, mostly in patients with previous abnormalities of lipid metabolism. The authors report here a case of a 65-year-old male bearing advanced colon carcinoma who developed hypertriglyceridemia during long-term interferon-alpha treatment in association with 5 fluorouracil administration. Hypertriglyceridemia was maintained within acceptable levels, without adjusting the treatment plan, by an appropriate diet and gemfibrosil administration.

Tomato Powder Inhibits Hepatic Steatosis and Inflammation Potentially Through Restoring SIRT1 Activity and Adiponectin Function Independent of Carotenoid Cleavage Enzymes in Mice

SCOPE

Beta-carotene-15,15'-oxygenase (BCO1) and beta-carotene-9',10'-oxygenase (BCO2) metabolize lycopene to biologically active metabolites, which can ameliorate nonalcoholic fatty liver disease (NAFLD). We investigate the effects of tomato powder (TP containing substantial lycopene (2.3 mg/g)) on NAFLD development and gut microbiome in the absence of both BCO1 and BCO2 in mice.

METHOD AND RESULTS

BCO1^-/- /BCO2^-/- double knockout mice were fed a high fat diet (HFD) alone (n = 9) or with TP feeding (n = 9) for 24 weeks. TP feeding significantly reduced pathological severity of steatosis and hepatic triglyceride levels in BCO1^-/- /BCO2^-/- mice (p < 0.04 vs HFD alone). This was associated with increased SIRT1 activity, nicotinamide phosphoribosyltransferase expression and AMP-activated protein kinase phosphorylation, and subsequently decreased lipogenesis, hepatic fatty acid uptake, and increasing fatty acid β-oxidation (p < 0.05). TP feeding significantly decreased mRNA expression of proinflammatory genes (tnf-α, il-1β, and il-6) in both liver and mesenteric adipose tissue, which were associated with increased plasma adiponectin and hepatic adiponectin receptor-2. Multiplexed 16S rRNA gene sequencing was performed using DNA extracted from cecum fecal samples. TP feeding increased microbial richness and decreased relative abundance of the genus Clostridium.

CONCLUSION

Dietary TP can inhibit NAFLD independent of carotenoid cleavage enzymes, potentially through increasing SIRT1 activity and adiponectin production and decreasing Clostridium abundance.

White adipose tissue IFN-γ expression and signalling along the progression of rodent cancer cachexia

Cachexia is associated with increased morbidity and mortality in cancer. The White adipose tissue (WAT) synthesizes and releases several pro-inflammatory cytokines that play a role in cancer cachexia-related systemic inflammation. IFN-γ is a pleiotropic cytokine that regulates several immune and metabolic functions. To assess whether IFN-γ signalling in different WAT pads is modified along cancer-cachexia progression, we evaluated IFN-γ receptors expression (IFNGR1 and IFNGR2) and IFN-γ protein expression in a rodent model of cachexia (7, 10, and 14days after tumour implantation). IFN-γ protein expression was heterogeneously modulated in WAT, with increases in the mesenteric pad and decreased levels in the retroperitoneal depot along cachexia progression. Ifngr1 was up-regulated 7days after tumour cell injection in mesenteric and epididymal WAT, but the retroperitoneal depot showed reduced Ifngr1 gene expression. Ifngr2 gene expression was increased 7 and 14days after tumour inoculation in mesenteric WAT. The results provide evidence that changes in IFN-γ expression and signalling may be perceived at stages preceding refractory cachexia, and therefore, might be employed as a means to assess the early stage of the syndrome.

In vitro effect of endotoxin on lipolysis and lipoprotein lipase activity in adipocytes from lean, obese and obese diabetic Zucker rats

Endotoxemia and sepsis in non diabetic rats are associated with alterations in adipose tissue metabolism evidenced by an increase in lipolysis and decrease in lipoprotein lipase (LPL) activity. The purpose of this study was to determine the in vitro effect of endotoxin (LPS) on lipolysis and the activities of LPL in epididymal adipocytes isolated from 11-12-week-old obese diabetic, obese, and lean rats. Epinephrine-stimulated lipolysis was higher in the adipocytes from obese diabetic and obese rats than lean rats. Maximal lipolytic response for all groups occurred with 10-5 M of epinephrine. LPS increased the lipolytic rate in adipocytes from the obese and obese diabetic rats by 58% and 97%, respectively, in comparison to the lean rats. Heparin-releasable and extractable LPL activities were suppressed in LPS-treated adipocytes from lean rats; heparin-releasable, but not extractable LPL activity, was depressed in adipocytes from obese rats. The LPS-induced depression in LPL activities did not occur in adipocytes from obese diabetic rats. Since LPL is not altered, adipose tissue from the obese diabetic rats may not become depleted when challenged with endotoxin as is the case for the normal endotoxin-treated lean rat with diminished LPL activity.

Potentiation of Porcine Circovirus 2-induced Postweaning Multisystemic Wasting Syndrome by Porcine Parvovirus Is Associated with Excessive Production of Tumor Necrosis Factor-α

This study investigated the potentiation of porcine circovirus 2 (PCV2)-induced postweaning multisystemic wasting syndrome by porcine parvovirus (PPV) and found it was associated with excessive production of tumor necrosis factor-α (TNF-α). Colostrum-deprived conventional pigs were inoculated intranasally with PCV2 or PPV alone or in combination (PCV2 and PPV). In vitro assay of TNF-α, obtained from alveolar macrophages coinfected with PCV2 and PPV, showed a significant increase in TNF-α compared to single infection of macrophages with either PCV2 or PPV alone ( P < 0.05). All pigs inoculated with PCV2 and PPV developed severe postweaning wasting syndrome, whereas clinical signs (e.g., weight loss) were present but perhaps less severe in either PCV2- or PPV-inoculated pigs. Compared to the pigs inoculated with PCV2 or PPV alone, pigs inoculated dually with PCV2 and PPV showed significantly ( P < 0.05) increased levels of TNF-α. Levels of TNF-α in the sera were reversely correlated with the body weight in pigs experimentally infected with dual inoculation of PCV2 and PPV ( rs = -0.92, P < 0.001). These data suggest that a potentiation of PPV in PCV2-induced PMWS is associated with the excessive production of TNF-α.

Tumor Necrosis Factor-Α, Interleukin-6, C-Reactive Protein Levels and Insulin Resistance Associated with Type 2 Diabetes in Abdominal Obesity Women

We aim to investigate the association between elevated tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and high sensitivity-C-reactive protein (hs-CRP) with type 2 diabetes mellitus (T2DM) in abdominal obesity (AO) women subjects. A total of 428 AO subjects (age 48.4 ± 10.2 years), and 107 non-AO women subjects (age 48.8 ± 11.8 years) were enrolled for the all biochemistry testing, inflammatory cytokines, fasting insulin and Homeostasis Model Assessment of insulin resistance (HOMA-IR). Body mass index, waist circumference (WC), blood pressure (BP), plasma glucose (Glu), triglyceride (TG), insulin, HOMA-IR and inflammatory cytokines were significantly higher and lower total antioxidant capacity, HDL-C in AO subjects (p < 0.05). WC was significantly correlated with BP, Glu, TG, LDL-C, insulin, HOMA-IR, TNF-α, IL-6 and negative correlation with HDL-C in AO subjects. Elevation of TNF-α, IL-6, hs-CRP and insulin resistance were significantly associated with T2DM in AO subjects, after adjusting with insulin resistance, increased oxidative stress, elevated TG and reduced HDL-C by using multiple logistic regression analysis. In conclusions, elevation of inflammatory cytokines, oxidative stress and insulin resistance were associated with T2DM in AO women subjects. These inflammatory cytokines are positively associated with T2DM and may have a causal relation with an increased oxidative stress and insulin resistance in these AO women subjects.

The occurrence of enteric viruses in Light Turkey Syndrome

Two studies were conducted to determine the role of enteric viruses in Light Turkey Syndrome (LTS), which is characterized by lower weight in market age turkeys than their standard breed character. In the surveillance study, we selected four LTS and two non-LTS turkey flocks in Minnesota and collected faecal samples at 2, 3, 5 and 8-weeks of age. Astrovirus, rotavirus, and reovirus were detected alone or in various combinations in both LTS and non-LTS flocks. No coronavirus was detected in LTS flocks and no corona- or reovirus was detected in non-LTS flocks. In the second study, 2-week-old turkey poults were divided into two groups; Group A (challenged) was inoculated orally with 10% pooled faecal suspension from LTS flocks and group B (control) was inoculated with phosphate buffered saline (PBS). Clinical signs of depression, huddling, and lack of uniform size were observed in the challenged group but not in the control group. diarrhoea was observed in both groups but was more severe in the challenged group than in the control group. Birds in the challenged group shed astrovirus, rotavirus and reovirus, while the control group shed only astrovirus. Virus shedding in both groups was observed for up to nine weeks of age. Significantly lower body weights were seen in the challenged group starting at seven weeks of age and lasting until 20 weeks of age. These findings suggest that viral enteritis at an early age may set up conditions for the development of LTS in adult turkeys.

Adipokines and biochemical changes in Egyptian obese subjects: possible variation with sex and degree of obesity

The purpose of this study was firstly to evaluate the adipokines and biochemical changes in obese subjects in relation to different grades of obesity and in relation to gender difference (males versus females) and secondly to evaluate the role of TNF-α in obesity. From January 2013 to February 2014, a total number of 120 non-diabetic subjects of both sexes were recruited and randomly selected from Dr. Abd-Elhamid Elsheikh center for physiotherapy and weight control, El-menofia-Egypt. Those subjects were classified according to their sex into two main groups; the female group and the male group. The female group (60 women) was distributed according to BMI into group 1 (15 lean women), group 2 (15 class I obese women), group 3 (15 class II obese women), and group 4 (15 class III obese women). The male group (60 men) was also distributed according to the BMI into group 1 (15 lean men), group 2 (15 class I obese men), group 3 (15 class II obese men), and group 4 (15 class III obese men). All individuals enrolled in the study were submitted to weight and height measurements with subsequent calculation of body mass index. Fasting blood samples were collected from all participants for quantitative determination of blood glucose, serum lipid, TNF-α, leptin, and adiponectin levels. One-way analysis of variance followed by LSD post hoc test was used for comparison of variables. In obese subjects of both sexes, it was found that circulating leptin and TNF-α levels were significantly high (P<0.05) and positively correlated to BMI. In contrast to leptin, adiponectin concentrations were significantly low (P<0.05) and inversely correlated to BMI. Regarding gender difference, although serum leptin and adiponectin levels were higher in women than men, men showed higher atherogenic parameters. We conclude that leptin, TNF-α, and adiponectin were related to both BMI and grades of obesity. Furthermore, TNF-α may play a role in obesity.

Inflammation stimulates niacin receptor (GPR109A/HCA2) expression in adipose tissue and macrophages

Many of the beneficial and adverse effects of niacin are mediated via a G protein receptor, G protein-coupled receptor 109A/hydroxycarboxylic acid 2 receptor (GPR109A/HCA2), which is highly expressed in adipose tissue and macrophages. Here we demonstrate that immune activation increases GPR109A/HCA2 expression. Lipopolysaccharide (LPS), TNF, and interleukin (IL) 1 increase GPR109A/HCA2 expression 3- to 5-fold in adipose tissue. LPS also increased GPR109A/HCA2 mRNA levels 5.6-fold in spleen, a tissue rich in macrophages. In peritoneal macrophages and RAW cells, LPS increased GPR109A/HCA2 mRNA levels 20- to 80-fold. Zymosan, lipoteichoic acid, and polyinosine-polycytidylic acid, other Toll-like receptor activators, and TNF and IL-1 also increased GPR109A/HCA2 in macrophages. Inhibition of the myeloid differentiation factor 88 or TIR-domain-containing adaptor protein inducing IFNβ pathways both resulted in partial inhibition of LPS stimulation of GPR109A/HCA2, suggesting that LPS signals an increase in GPR109A/HCA2 expression by both pathways. Additionally, inhibition of NF-κB reduced the ability of LPS to increase GPR109A/HCA2 expression by ∼50% suggesting that both NF-κB and non-NF-κB pathways mediate the LPS effect. Finally, preventing the LPS-induced increase in GPR109A/HCA2 resulted in an increase in TG accumulation and the expression of enzymes that catalyze TG synthesis. These studies demonstrate that inflammation stimulates GPR109A/HCA2 and there are multiple intracellular signaling pathways that mediate this effect. The increase in GPR109A/HCA2 that accompanies macrophage activation inhibits the TG accumulation stimulated by macrophage activation.

Pyroglutamylated RF-amide peptide (QRFP) gene is regulated by metabolic endotoxemia

Pyroglutamylated RF-amide peptide (QRFP) is involved in the regulation of food intake, thermogenesis, adipogenesis, and lipolysis. The expression of QRFP in adipose tissue is reduced in diet-induced obesity, a mouse model in which plasma concentrations of endotoxins are slightly elevated. The present study investigated the role of metabolic endotoxemia (ME) on QRFP gene regulation. Our results uncovered the expression of QRFP in murine macrophages and cell lines. This expression has been found to be decreased in mice with ME. Low doses of lipopolysaccharide (LPS) transiently down-regulated QRFP by 59% in RAW264.7 macrophages but not in 3T3-L1 adipocytes. The effect of LPS on QRFP expression in macrophages was dependent on the inhibitor of kB kinase and TIR-domain-containing adapter-inducing interferon (IFN)-β (TRIF) but not myeloid differentiation primary response gene 88. IFN-β was induced by ME in macrophages. IFN-β sustainably reduced QRFP expression in macrophages (64%) and adipocytes (49%). IFN-γ down-regulated QRFP (74%) in macrophages only. Both IFNs inhibited QRFP secretion from macrophages. LPS-stimulated macrophage-conditioned medium reduced QRFP expression in adipocytes, an effect blocked by IFN-β neutralizing antibody. The effect of IFN-β on QRFP expression was dependent on phosphoinositide 3-kinase, p38 MAPK, and histone deacetylases. The effect of IFN-γ was dependent on MAPK/ERK kinase 1/2 and histone deacetylases. Macrophage-conditioned medium containing increased amounts of QRFP preserved adipogenesis in adipocytes. In conclusion, LPS induces IFN-β release from macrophages, which reduces QRFP expression in both macrophages and adipocytes in an autocrine/paracrine-dependent manner, suggesting QRFP as a potential biomarker in ME.

Non-alcoholic steatohepatitis and hepatocellular carcinoma: implications for lycopene intervention

Increased prevalence of non-alcoholic fatty liver disease (NAFLD) is one of the consequences of the current obesity epidemic. NAFLD is a major form of chronic liver disease that is highly prevalent in obese and overweight adults and children. Nonalcoholic steatohepatitis (NASH) is the severe form of NAFLD, and uncontrolled inflammation as displayed in NASH has been identified as one of the key events in enhancing hepatic carcinogenesis. Lycopene is a non-provitamin A carotenoid and the pigment principally responsible for the characteristic deep-red color of ripe tomato and tomato products, as well as some fruits and vegetables. Lycopene's innate antioxidant and anti-inflammatory properties have generated research interests on its capacity to protect against human diseases that are associated with oxidative stress and inflammation. In addition, differential mechanisms of lycopene metabolism including endogenous cleavage by carotenoid cleavage oxygenases (BCOs), generate lycopene metabolites that may also have significant impact on human disease development. However, it remains to be elucidated as to whether lycopene or its metabolites apolycopenoids have protective effects against obesity-related complications including inflammation and tumorigenesis. This article summarizes the in vivo experiments that elucidated molecular mechanisms associated with obesity-related hepatic inflammation and carcinogenesis. This review also provides an overview of lycopene metabolism, and the molecular pathways involved in the potential beneficial properties of lycopene and apolycopenoids. More research is clearly needed to fully unravel the importance of BCOs in tomato carotenoid metabolism and the consequence on human health and diseases.

Genistein and exercise do not improve cardiovascular risk factors in the ovariectomized rat

OBJECTIVE

To investigate the effect of either genistein, or exercise, or both, on parameters that are indicators of cardiovascular health.

METHODS

We investigated the effect of genistein treatment (300 mg genisten/kg body weight/day), or exercise training, or combined genistein and exercise training, for a period of 6 weeks on physical characteristics, cardiovascular plasma markers, blood pressure, aortic morphology, cardiac structure and oxidative stress in the ovariectomized (OVX) Sprague-Dawley rat. Comparisons were made with intact rats.

RESULTS

Ovariectomy (compared to intact) resulted in significant decreases in uterine weight (6-fold, p < 0.0001), insulin levels (4-fold, p = 0.0214), insulin/glucose ratio (3-fold, p = 0.0029), and tumor necrosis factor-α plasma levels (2-fold, p < 0.0001). Similarly, aortic blood pressure was significantly increased (by 8%, p < 0.0033) in OVX rats, without changes in aortic luminal or wall dimensions. Heart surface area was significantly increased (by 16%, p = 0.0160) in OVX rats and this was without changes in non-protein thiol levels (a marker of oxidative stress). Physical characteristics were not altered by treatment with genistein, or genistein with exercise, with the exception of increased uterine weight in OVX rats treated under these same conditions. There were no effects of genistein or exercise on indices of blood pressure and aortic morphology in the OVX rat. However, right ventricular nuclei count was reduced in sedentary genistein-treated rats compared to non-treated control OVX rats.

CONCLUSION

Our results indicate that administration of genistein at this dose, treadmill running, or the combination of both, are not associated with any improvement in cardiovascular function and structure, and risk factors in an ovariectomy model of postmenopause.

Sequences of acetyl CoA carboxylase promoter for tumour necrosis factor action

Tumour necrosis factor (TNF) inhibits the accumulation of acetyl CoA carboxylase (ACC) mRNA by decreasing the rate of ACC gene transcription. The ACC mRNA species found in 30A5 cells are generated from promoter II and TNF inhibits the accumulation of class 2 type mRNAs. By using 5' deletion mutants of promoter II fused to the bacterial chloramphenicol acetyltransferase (CAT) gene, the DNA mobility shift assay and the DNase I footprinting assay, the authors have identified the 30 bp from −389 to −359 as the TNF responsive element in promoter II. TNF treatment causes a decrease in the binding activity of nuclear protein(s) specific to the TNF responsive element. When the fragment containing the TNF responsive element was incorporated into the thymidine kinase promoter, the chimeric gene exhibited TNF induced inhibition of expression.

New-onset extremely low levels of high-density lipoprotein cholesterol

We report the case of a 55-year-old man who presented to the outpatient lipid clinic for his scheduled follow-up with severely low high-density lipoprotein cholesterol levels of new onset. Diagnostic workup showed that he was infected by visceral leishmaniasis. He was treated with liposomal amphotericin B and serum lipid levels returned to usual values.

Obesity, inflammation, and liver cancer

Obesity has become a universal and major public health problem with increasing prevalence in both adults and children in the 21st century, even in developing countries. Extensive epidemiological studies reveal a strong link between obesity and development and progression of various types of cancers. The connection between obesity and liver cancer is particularly strong and obesity often results in liver diseases such as non-alcoholic fatty liver disease (NAFLD) and the more severe non-alcoholic steatohepatitis (NASH). NASH is characterized by fatty liver inflammation and is believed to cause fibrosis and cirrhosis. The latter is a known liver cancer risk factor. In fact due to its much higher prevalence obesity may be a more substantial contributor to overall hepatocellular carcinoma burden than infection with hepatitis viruses. Here we review and discuss recent advances in elucidation of cellular and molecular alterations and signaling pathways associated with obesity and liver inflammation and their contribution to hepatocarcinogenesis.

Elevated adenosine deaminase activity in overweight and obese Indian subjects

OBJECTIVE

To determine adenosine deaminase activity in overweight and obese Indian subjects.

METHODS

This study comprised of 100 subjects. The body mass index (BMI) of subjects was calculated and adenosine deaminase activity was determined in their fasting blood sample. The study was divided into three groups depending upon BMI: Control (n = 40, BMI < 25 kg/m(2)), Overweight (n = 30, BMI 25-29.9 kg/m(2)) and Obese (n = 30, BMI ≥ 30 kg/m(2)).

RESULTS

The serum adenosine deaminase activity was significantly increased in overweight and obese subjects and as well as in combined overweight and obese group as compared to control (P < 0.0001).

CONCLUSION

Adenosine, an endogenous anti-inflammatory metabolite, is increased in response to inflammation produced by adipose tissue in obesity. However, adenosine deaminase acts on adenosine to convert it into inosine, thereby increasing adenosine deaminase activity in overweight and obese Indian subjects.

11-Hydroxy-β-steroid dehydrogenase gene expression in canine adipose tissue and adipocytes: stimulation by lipopolysaccharide and tumor necrosis factor α

The enzyme 11β-hydroxysteroid dehydrogenase 1 (11β-HSD-1) is expressed in a number of tissues in rodents and humans and is responsible for the reactivation of inert cortisone into cortisol. Its gene expression and activity are increased in white adipose tissue (WAT) from obese humans and may contribute to the adverse metabolic consequences of obesity and the metabolic syndrome. The extent to which 11β-HSD-1 contributes to adipose tissue function in dogs is unknown; the aim of the present study was to examine 11β-HSD-1 gene expression and its regulation by proinflammatory and anti-inflammatory agents in canine adipocytes. Real-time PCR was used to examine the expression of 11β-HSD-1 in canine adipose tissue and canine adipocytes differentiated in culture. The mRNA encoding 11β-HSD-1 was identified in all the major WAT depots in dogs and also in liver, kidney, and spleen. Quantification by real-time PCR showed that 11β-HSD-1 mRNA was least in perirenal and falciform depots and greatest in subcutaneous, omental, and gonadal depots. Greater expression was seen in the omental depot in female than in male dogs (P=0.05). Gene expression for 11β-HSD-1 was also seen in adipocytes, from both subcutaneous and visceral depots, differentiated in culture; expression was evident throughout differentiation but was generally greatest in preadipocytes and during early differentiation, declining as cells progressed to maturity. The inflammatory mediators lipopolysaccharide and tumor necrosis factor α had a main stimulatory effect on 11β-HSD-1 gene expression in canine subcutaneous adipocytes, but IL-6 had no significant effect. Treatment with dexamethasone resulted in a significant time- and dose-dependent increase in 11β-HSD-1 gene expression, with greatest effects seen at 24 h (2 nM: approximately 4-fold; 20 nM: approximately 14-fold; P=0.010 for both). When subcutaneous adipocytes were treated with the peroxisome proliferator activated receptor γ agonist rosiglitazone, similar dose- and time-dependent effects were noted. However, no effects were seen when adipocytes from the gonadal WAT depot were treated with rosiglitazone. The induction of 11β-HSD-1 expression, by the pro-inflammatory cytokine tumor necrosis factor α and by lipopolysaccharide may have implications for the pathogenesis of obesity and its associated diseases in the dog.

Inflammation inhibits GPR81 expression in adipose tissue

OBJECTIVE AND DESIGN

The aim of this study was to examine the expression of G protein-coupled receptor 81 (GPR81) in mouse adipose tissue in response to inflammatory stimuli. GPR81 is activated by lactate resulting in the inhibition of lipolysis.

MATERIALS AND TREATMENT

Mice were injected with saline, lipopolysaccharide (LPS), zymosan, or turpentine, N = 5 per group. 3T3-L1 adipocytes were treated with tumor necrosis factor alpha, interleukin (IL)-l beta, IL-6, or interferon gamma.

METHODS

GPR81 expression levels were measured by real-time PCR and statistical significance was determined by Student's t test.

RESULTS

LPS resulted in a marked decrease in GPR81 mRNA level in mouse adipose tissue in C57BL/6 and OuJ mice, an effect that was not observed in HeJ mice, which have a mutation in TLR4. Zymosan and turpentine also decreased adipose tissue GPR81 expression. Cytokine treatment of 3T3-L1 adipocytes had no effect on GPR81 expression. GPR81 expression was decreased in ob/ob mice, an animal model of type 2 diabetes that is characterized by inflammation.

CONCLUSION

Inflammation decreases the expression of GPR81 in adipose tissue.

Inflammation inhibits the expression of phosphoenolpyruvate carboxykinase in liver and adipose tissue

Inhibition of adipocyte triglyceride biosynthesis is required for fatty acid mobilization during inflammation. Triglyceride biosynthesis requires glycerol 3-phosphate and phosphoenolpyruvate carboxykinase (PEPCK) plays a key role. We demonstrate that LPS, zymosan, and TNF-α decrease PEPCK in liver and fat. Turpentine decreases PEPCK in liver, but not in fat. The LPS-induced decrease in PEPCK does not occur in TLR4 deficient animals, indicating that this receptor is required. The LPS-induced decrease in hepatic PEPCK does not occur in TNF receptor/IL-1 receptor knockout mice, but occurs in fat, indicating that TNF-α/IL-1 is essential for the decrease in liver but not fat. In 3T3-L1 adipocytes TNF-α, IL-1, IL-6, and IFNγ inhibit PEPCK indicating that there are multiple pathways by which PEPCK is decreased in adipocytes. The binding of PPARγ and RXRα to the PPARγ response element in the PEPCK promoter is markedly decreased in adipose tissue nuclear extracts from LPS treated animals. Lipopolysaccharide and zymosan reduce PPARγ and RXRα expression in fat, suggesting that a decrease in PPARγ and RXRα accounts for the decrease in PEPCK. Thus, there are multiple cytokine pathways by which inflammation inhibits PEPCK expression in adipose tissue which could contribute to the increased mobilization of fatty acids during inflammation.

Regulation of fat specific protein 27 by isoproterenol and TNF-α to control lipolysis in murine adipocytes

The lipid droplet-associated fat specific protein 27 (FSP27) suppresses lipolysis and thereby enhances triglyceride accumulation in adipocytes. We and others have recently found FSP27 to be a remarkably short-lived protein (half-life, 15 min) due to its rapid ubiquitination and proteasomal degradation. Thus, we tested the hypothesis that lipolytic agents such as tumor necrosis factor-α (TNF-α) and isoproterenol modulate FSP27 levels to regulate FFA release. Consistent with this concept, we showed that the lipolytic actions of TNF-α, interleukin-1β (IL-1β), and IFN-γ are accompanied by marked decreases in FSP27 expression and lipid droplet size in mouse adipocytes. Similar depletion of FSP27 using short interfering RNA (siRNA) mimicked the lipolysis-enhancing effect of TNF-α, while maintaining stable FSP27 levels using expression of hemagglutinin epitope-tagged FSP27 blocked TNF-α-mediated lipolysis. In contrast, we show the robust lipolytic action of isoproterenol is paradoxically associated with increases in FSP27 levels and a delayed degradation rate corresponding to decreased ubiquitination. This catecholamine-mediated increase in FSP27 abundance, probably a feedback mechanism for restraining excessive lipolysis by catecholamines, is mimicked by forskolin or 8-bromo-cAMP treatment and is prevented by the protein kinase A (PKA) inhibitor KT5720 or by PKA depletion using siRNA. Taken together, these data identify the regulation of FSP27 as an important intermediate in the mechanism of lipolysis in adipocytes in response to TNF-α and isoproterenol.

IL-17 in obesity and adipogenesis

The pro-inflammatory cytokine interleukin (IL)-17 (also known as IL-17) has been associated with induction of tissue inflammation. Obese individuals exhibit many symptoms of chronic low-grade inflammation, suggesting that IL-17 may impact adipose tissue. However, the role of IL-17 in obesity is largely unexplored. Emerging studies indicate that obesity selectively promotes expansion of the Th17 T-cell lineage, exacerbating disease in murine models of autoimmunity such as EAE and colitis. Human studies support this concept, as new clinical studies suggest that IL-17 is expressed at elevated levels in obese individuals. Conversely, however, an anti-adipogenic role for IL-17 is becoming evident, and therefore the interconnections between IL-17 and fat metabolism may be quite complex. Here, we consolidate the potential implications of IL-17 in relation to obesity and describe the emerging data regarding the role of IL-17 in adipose tissue.

Targeting inflammation-induced obesity and metabolic diseases by curcumin and other nutraceuticals

Extensive research within the past two decades has revealed that obesity, a major risk factor for type 2 diabetes, atherosclerosis, cancer, and other chronic diseases, is a proinflammatory disease. Several spices have been shown to exhibit activity against obesity through antioxidant and anti-inflammatory mechanisms. Among them, curcumin, a yellow pigment derived from the spice turmeric (an essential component of curry powder), has been investigated most extensively as a treatment for obesity and obesity-related metabolic diseases. Curcumin directly interacts with adipocytes, pancreatic cells, hepatic stellate cells, macrophages, and muscle cells. There, it suppresses the proinflammatory transcription factors nuclear factor-kappa B, signal transducer and activators of transcription-3, and Wnt/beta-catenin, and it activates peroxisome proliferator-activated receptor-gamma and Nrf2 cell-signaling pathways, thus leading to the downregulation of adipokines, including tumor necrosis factor, interleukin-6, resistin, leptin, and monocyte chemotactic protein-1, and the upregulation of adiponectin and other gene products. These curcumin-induced alterations reverse insulin resistance, hyperglycemia, hyperlipidemia, and other symptoms linked to obesity. Other structurally homologous nutraceuticals, derived from red chili, cinnamon, cloves, black pepper, and ginger, also exhibit effects against obesity and insulin resistance.

Effects of TWEAK (TNF superfamily member 12) on differentiation, metabolism, and secretory function of human primary preadipocytes and adipocytes

Expansion of adipose tissue mass by hypertrophy and hyperplasia is the hallmark of obesity. An automated cDNA screen was established to identify secreted human proteins with an inhibitory effect on adipocyte differentiation and, thereby, a potential inhibitory effect on adipose tissue growth. A member of the TNF superfamily, TNF-like weak inducer of apoptosis (TWEAK; TNF superfamily 12) was identified by means of high-throughput screening with the lipophilic dye Nile Red as an inhibitor of murine adipocyte differentiation and, subsequently, also of human adipocyte differentiation. TWEAK inhibited lipid deposition in a dose-dependent manner without causing cytotoxic effects. This inhibitory action was mimicked by an agonistic antibody of the TWEAK receptor. The TWEAK receptor (fibroblast growth factor inducible 14; CD266) was expressed on human primary preadipocytes and mature adipocytes. Knockdown of TWEAK receptor by short-hairpin RNA abolished the inhibitory effect of TWEAK on cell differentiation, demonstrating that the effects of TWEAK are mediated by its specific receptor. Inhibition of differentiation was the result of interference at an early step of transcriptional activation as assessed by decreased peroxisome proliferator-activated receptor-gamma, CCAAT enhancer-binding protein alpha (C/EBPalpha), and CCAAT enhancer-binding protein beta (C/EBPbeta) mRNA expression. In contrast to TNFalpha, basal and insulin-stimulated glucose uptake and lipolysis of terminally differentiated mature adipocytes and secretion of proinflammatory cytokines were not altered in the presence of TWEAK, and nuclear factor kappa B activity was only weakly induced. We conclude from our findings that TWEAK and the corresponding agonistic antibody have the potential to prevent adipose tissue growth without adversely influencing central metabolic pathways or proinflammatory cytokine secretion in adipose tissue.

Interleukin-17A inhibits adipocyte differentiation in human mesenchymal stem cells and regulates pro-inflammatory responses in adipocytes

The immune system is closely linked to human metabolic diseases. Serum levels of IL-6 increase with obesity and insulin resistance. Not only does IL-6 decrease the insulin sensitivity of human cells such as adipocytes, but it also regulates the lineage commitment of naïve T cells into interleukin (IL)-17A-producing CD4(+) T (Th17) cells. Although IL-17A exerts a variety of effects on somatic tissues, its functional role in human adipocytes has not been identified. In this work, we show that IL-17A inhibits adipocyte differentiation in human bone marrow mesenchymal stem cells (hBM-MSCs), while promoting lipolysis of differentiated adipocytes. We find that IL-17A increases both mRNA and protein secretion of IL-6 and IL-8 during adipocyte differentiation in hBM-MSCs. IL-17A up-regulates cyclooxygenase (COX)-2 gene expression and thereby increases the level of prostaglandin (PG) E(2) in differentiated adipocyes. The suppression of anti-adipogenic PGE(2) by COX inhibitors such as aspirin and NS-398 partially blocked the effect of IL-17A on adipocyte differentiation in hBM-MSCs. Therefore, IL-17A exhibits its inhibitory effect in part via the COX-2 induction in differentiated adipocytes. In addition, treatment with anti-IL-17A antibody neutralizes IL-17A-mediated effects on adipocyte differentiation and function. These results suggest that IL-17A plays a regulatory role in both the metabolic and inflammatory processes of human adipocytes, similar to other pro-inflammatory cytokines such as IL-1, IFNgamma, and TNFalpha.

LPS and proinflammatory cytokines decrease lipin-1 in mouse adipose tissue and 3T3-L1 adipocytes

Infection and inflammation affect adipose triglyceride metabolism, resulting in increased plasma free fatty acid (FFA) and VLDL levels during the acute-phase response. Lipin-1, a multifunctional protein, plays a critical role in adipose differentiation, mitochondrial oxidation, and triglyceride synthesis. Here, we examined whether LPS [a Toll-like receptor (TLR)-4 activator], zymosan (a TLR-2 activator), and proinflammatory cytokines regulate lipin-1 in adipose tissue. LPS administration caused a marked decrease in the levels of lipin-1 mRNA and protein in adipose tissue. The decrease in lipin-1 mRNA levels occurred rapidly and lasted for at least 24 h. In contrast, lipin-2 and -3 mRNA levels did not change, suggesting specific repression of lipin-1. Zymosan similarly decreased lipin-1 mRNA without affecting lipin-2 or lipin-3 mRNA levels. To determine the pathways by which LPS repressed lipin-1, we examined the effect of proinflammatory cytokines on cultured adipocytes. In 3T3-L1 adipocytes, TNF-alpha, IL-1beta, and IFN-gamma, but not LPS or IL-6, caused a decrease in lipin-1 mRNA levels. Furthermore, TNF-alpha and IL-1beta administration also decreased mRNA levels of lipin-1 in adipose tissue in mice. Importantly, the LPS-induced decrease in lipin-1 mRNA levels was significantly but not totally blunted in TNF-alpha/IL-1 receptor-null mice compared with controls, suggesting key roles for TNF-alpha/IL-1beta and other cytokines in mediating LPS-induced repression of lipin-1. Together, our results demonstrate that expression of lipin-1, one of the essential triglyceride synthetic enzymes, was suppressed by LPS, zymosan, and proinflammatory cytokines in mouse adipose tissue and in cultured 3T3-L1 adipocytes, which could contribute to a decrease in the utilization of FFA to synthesize triglycerides in adipose tissue, thus promoting the release of FFA into the circulation.

Interferon-gamma, a Th1 cytokine, regulates fat inflammation: a role for adaptive immunity in obesity

Adipose tissue (AT) can accumulate macrophages and secrete several inflammatory mediators. Despite its pivotal role in the progression of chronic inflammatory processes such as atherosclerosis, the adaptive role of immunity in obesity remains poorly explored. Visceral AT of diet-induced obese C57BL/6 mice had higher numbers of both CD4(+) and CD8(+) T cells than lean controls, monitored by flow cytometry. When stimulated in vitro, T cells from obese AT produced more interferon (IFN)gamma than those from controls. AT from obese animals also had more cells expressing I-A(b), a mouse class II histocompatibility marker implicated in antigen presentation, as determined by immunostaining. Differentiated 3T3-L1 cells stimulated with recombinant IFNgamma or T-helper 1-derived supernatant produced several chemokines and their mRNAs. Obese IFNgamma-deficient animals had significantly reduced AT expression of mRNA-encoding inflammatory genes such as tumor necrosis factor-alpha and monocyte chemoattractant protein-1, decreased AT inflammatory cell accumulation, and better glucose tolerance than control animals consuming the same diet. Obese mice doubly deficient for IFNgamma receptor and apolipoprotein (Apo)E on a mixed 129SvEv/C57BL/6 (129/B6) genetic background, despite exhibiting similar AT mRNA levels of tumor necrosis factor-alpha and monocyte chemoattractant protein-1 as 129/B6-ApoE(-/-) controls, had decreased expression of important T cell-related genes, such as IFNgamma-inducible protein-10 and I-A(b), and lower plasma triglycerides and glucose. These results indicate a role for T cells and IFNgamma, a prototypical T-helper 1 cytokine, in regulation of the inflammatory response that accompanies obesity.

Induction of the human heat shock promoter HSP70B by nutritional stress: implications for cancer gene therapy

BACKGROUND

We designed and tested, in vitro, an adenoviral construct containing the feline interleukin-12 (IL-12) gene under control of the heat-inducible promoter HSP70B. This construct, AdhspfIL12, was used in a phase I trial in feline soft tissue sarcomas. During the course of our experiments, we noted that IL-12 was being produced in the transfected Crandell Feline Kidney (CrFK) cells under certain conditions even in the absence of hyperthermia. This observation was further explored to identify the cause of this unintended HSP70B induction.

MATERIALS AND METHODS

We used real-time PCR as a sensitive method to quantitatively detect the presence of even small amounts of IL-12 mRNA. This served as a surrogate indicator of HSP70B induction. Various conditions were tested to induce the heat shock promoter, including nutritional deprivation, radiation and changes in pH.

RESULTS

Nutritional stresses, specifically the absence of glucose and glutamine, could induce the heat shock promoter, thus, resulting in production of the downstream gene product. Other factors known to trigger the heat shock response, pH change, and reactive oxygen species production were also studied but were not found to contribute to heat shock promoter induction in our setting.

CONCLUSIONS

The human heat shock promoter (HSP70B) is reported to be an efficient and tightly regulated promoter. We discovered, using sensitive real-time PCR techniques, that it can also be induced in response to cellular nutrient stresses. The pros and cons of this phenomenon and its implications for cancer gene therapy are discussed.

Serum amyloid A protein regulates the expression of porcine genes related to lipid metabolism

Serum amyloid A protein (SAA) is an apolipoprotein that can replace apolipoprotein A1 (apoA1) as the major apolipoprotein of HDL. Porcine hepatic SAA mRNA is increased by dietary docosahexaenoic acid (DHA) treatment. The purpose of this study was to investigate the role of SAA protein in regulating gene expression related to lipid metabolism in pigs. First, we demonstrated that the 100-micromol/L DHA treatment increased SAA and apoA1 mRNA expression in porcine hepatic cell cultures (P < 0.05). Secondly, we produced porcine SAA recombinant protein and found that the addition of SAA to porcine preadipocytes in culture stimulated interleukin-6 (IL-6) mRNA expression (P < 0.05), indicating a similar biological function of porcine SAA and human SAA. We also found PPARalpha and PPARgamma mRNA were decreased (40 and 60%, respectively) in differentiated adipocytes after treatment with 2 mumol/L SAA. SAA treatment also increased inflammatory cytokine gene expression (IL-6 and tumor necrosis factor alpha) and glycerol release (P < 0.05), indicating increased lipolysis. Because the expression of perilipin, a lipid droplet-protective protein, was reduced by the SAA treatment, we hypothesized that SAA increased lipolysis by decreasing the expression of perilipin, which would then allow an increase in hormone sensitive lipase activity. In conclusion, we demonstrated that the DHA-induced SAA gene expression decreased PPAR expression and consequently downregulated the expression of several genes involved in lipid metabolism. Accordingly, SAA may play a critical role in mediating the function of dietary DHA on lipid metabolism and could be a factor in regulating obesity.

Emerging drugs for cancer cachexia

Cachexia is a complex syndrome. The main components of this pathological state are anorexia and metabolic abnormalities such as glucose intolerance, fat depletion and muscle protein catabolism among others. The altered metabolic status generates a high degree of energetic inefficiency that results in weight loss, fatigue and a considerable loss of muscle and, therefore, asthenia. The aim of the present article is to review the different therapeutic approaches and emerging drugs that have been designed to fight and counteract cachexia associated with cancer.

Human tumour necrosis factors: structure and receptor interactions

Activation of lymphoid and myeloid cells causes the production of factors cytotoxic to various tumour cell types in vitro and in vivo. We have investigated the biochemistry, molecular biology and mechanism of action of two such factors. The factor derived from a myeloid cell line was named TNF-alpha (previously referred to as TNF) and that derived from lymphoid cells named TNF-beta (previously called lymphotoxin). Both proteins were purified from the conditioned media of the human cell lines and sequenced. Structural information revealed that TNF-alpha is 157 amino acid residues long and contains one disulphide bond. TNF-beta is a glycoprotein of 171 amino acids that contains no cysteine residues. Protein sequence information was used to isolate and characterize cDNAs for TNF-alpha and TNF-beta by recombinant DNA methods. The expression of the cDNAs in Escherichia coli made available large quantities of these proteins for biological studies. The two proteins are 31% identical and 52% homologous to each other. The genes for both cytokines are approximately three kilobases in size and are closely linked on human chromosome six. TNF-alpha and TNF-beta both bind to various cell types via a single class of high affinity receptors. On most cells the same receptor is recognized by both cytokines. The receptors for TNF-alpha can be up-regulated by both interferons and lectins. Up-regulation of receptors by interferons is accompanied by synergistic enhancement of the biological response whereas up-regulation by lectins results in an antagonistic response. Besides antiproliferative effects, both cytokines exhibit direct antiviral effects on infection by both DNA and RNA viruses.

Acute and selective inhibition of adipocyte glyceroneogenesis and cytosolic phosphoenolpyruvate carboxykinase by interferon gamma

Interferon gamma (IFN-gamma) was previously shown to promote fatty acid (FA) release from adipose tissue (AT). Net lipolysis is an equilibrium between triglyceride breakdown and FA re-esterification. The latter requires activated glyceroneogenesis for glycerol-3-phosphate synthesis and increased cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), the key enzyme in this pathway. We wondered whether glyceroneogenesis and PEPCK-C would be IFN-gamma targets. We injected mice with IFN-gamma, and exposed either AT explants and isolated adipocytes from humans and mice or 3T3-F442A adipocytes to IFN-gamma before monitoring expression of genes involved in lipid metabolism and the metabolic consequences. We show that IFN-gamma induces a large increase in FA release without affecting glycerol output and decreases [1-(14)C]-pyruvate incorporation into lipids, thus demonstrating that FA re-esterification is reduced due to diminished glyceroneogenesis. A series of mRNA encoding proteins involved in FA metabolism remained unaffected by IFN-gamma, while that of PEPCK-C was rapidly and drastically lowered. IFN-gamma effect opposed that of the beta-agonist isoproterenol and of 8-Br-cAMP. In IFN-gamma-treated mice, PEPCK-C gene expression was decreased in AT, but not in liver or kidney. Thus, IFN-gamma exerts a tissue-specific action in rodents and humans, having glyceroneogenesis and the PEPCK-C gene as selective targets to intensify FA release from adipocytes.

Ectopic fat accumulation and metabolic syndrome

The recent escalation of obesity from an individual health problem to a major public health issue reaching epidemic proportions has drawn attention to a constellation of abnormalities (abdominal obesity, hypertension and dyslipidaemia) collectively referred to as metabolic syndrome. As an indicator of insulin resistance and a harbinger of diabetes, this syndrome has been associated with major cardiovascular mortality and morbidity. Yet, the exact pathophysiological events leading to the development of metabolic syndrome remain unknown. We review some of the current literature on the pathogenesis of metabolic syndrome with an emphasis on the role of ectopic lipid accumulation.

Type II nuclear hormone receptors, coactivator, and target gene repression in adipose tissue in the acute-phase response

The acute-phase response (APR) leads to alterations in lipid metabolism and type II nuclear hormone receptors, which regulate lipid metabolism, are suppressed, in liver, heart, and kidney. Here, we examine the effect of the APR in adipose tissue. In mice, lipopolysaccharide produces a rapid, marked decrease in mRNA levels of nuclear hormone receptors [peroxisome proliferator-activated receptor gamma (PPARgamma), liver X receptor alpha (LXRalpha) and LXRbeta, thyroid receptor alpha (TRalpha) and TRbeta, and retinoid X receptor alpha (RXRalpha) and RXRbeta] and receptor coactivators [cAMP response element binding protein, steroid receptor coactivator 1 (SRC1) and SRC2, thyroid hormone receptor-associated protein, and peroxisome proliferator-activated receptor gamma co-activator 1alpha (PGC1alpha) and PGC1beta] along with decreased expression of target genes (adipocyte P2, phosphoenolpyruvate carboxykinase, glycerol-3-phosphate acyltransferase, ABCA1, apolipoprotein E, sterol-regulatory element binding protein-1c, glucose transport protein 4 (GLUT4), malic enzyme, and Spot14) involved in triglyceride (TG) and carbohydrate metabolism. We show that key TG synthetic enzymes, 1-acyl-sn-glycerol-3-phosphate acyltransferase-2, monoacylglycerol acyltransferase 1, and diacylglycerol acyltransferase 1, are PPARgamma-regulated genes and that they also decrease in the APR. In 3T3-L1 adipocytes, tumor necrosis factor-alpha (TNF-alpha) significantly decreases PPARgamma, LXRalpha and LXRbeta, RXRalpha and RXRbeta, SRC1 and SRC2, and PGC1alpha and PGC1beta mRNA levels, which are associated with a marked reduction in receptor-regulated genes. Moreover, TNF-alpha significantly reduces PPAR and LXR response element-driven transcription. Thus, the APR suppresses the expression of many nuclear hormone receptors and their coactivators in adipose tissue, which could be a mechanism to coordinately downregulate TG biosynthesis and thereby redirect lipids to other critical organs during the APR.

Biochemical mechanism of insulin sensitization, lipid modulation and anti-atherogenic potential of PPAR alpha/gamma dual agonist: Ragaglitazar

The current goal in the treatment of diabetes is not only to enhance the glycemic control but also to improve the associated cardiovascular risk factors. Among many of the strategies available, a co-ligand of PPARalpha and gamma in a single molecule which combines the insulin sensitizing potential of PPARgamma and the beneficial lipid modulating properties of PPARalpha agonism, has gained attention in the recent past. Here we report the biochemical mechanism by which a dual PPAR alpha/gamma agonist Ragaglitazar (Raga) achieves this goal. The PPARalpha component of Raga appears to contribute to a significant increase in beta oxidation, ApoA1 secretion and inhibition of TG biosynthesis in HepG2 cells. These effects of Raga at 60 microM were similar to that shown by Fenofibrate (Feno) at 250 microM. The PPARgamma component of Raga showed significant G3PDH activity and TG accumulation with a corresponding increase in aP2 expression in 3T3L1 cells. Significantly reduced levels of IL-6 and TNFalpha were observed in the culture supernatants of Raga treated 3T3L1 cells. Raga resulted in significant insulin dependent glucose uptake in 3T3L1 with a corresponding increase in GLUT4 expression. Further, Raga showed a significant cholesterol efflux with a corresponding increase in ABCA1 protein expression in THP-1 macrophages. In conclusion, Raga activates both PPARalpha and gamma regulated pathway in adipocytes as well as in hepatocytes which together contributes for its insulin sensitizing and lipid lowering activity. In addition the dual activation of PPAR alpha/gamma also shows an athero-protective potential by inducing reverse cholesterol efflux and inhibiting the pro-inflammatory cytokines.

Patogenia de la lipodistrofia y de las alteraciones metabólicas asociadas a la infección por el VIH

Lipodystrophy, and the metabolic alterations (dislipemia, insulin-resistance) associated with human immunodeficiency virus (HIV) infection, is a multifactorial syndrome due to the interaction of host related factors (cellular immune status, diet, gene mutations), viral factors (cytokine synthesis, polyunsaturated fatty acid or PUFA depletion), and pharmacological effects (mitochondrial DNA-polymerase inhibition, lipolysis inhibition, adiponectin synthesis reduction). HIV probably modifies the adipocyte differentiation and the lipid metabolism. This retroviral effect is mediated by proinflammatory cytokines (tumor necrosis factor) and the participation of other factors (drugs, diet), all in the context of a particular host genetic setting. The adipocyte (and several cellular receptors, fatty acids, membrane proteins, and cytokines) plays a central role in the pathogenesis of HIV-associated lipodystrophy.

The prevention and treatment of metabolic syndrome and high-risk obesity

PURPOSE OF REVIEW

The prevalence of obesity is increasing at an alarming rate, and the obesity epidemic is driving the epidemic in type 2 diabetes. High-risk obesity is characterized by abdominal obesity with evidence of abnormal glucose and lipid metabolism, and a state of heightened inflammation.

RECENT FINDINGS

With increasing body weight, lipid accumulation occurs not only in adipose tissue, but in other organs as well. This 'lipotoxicity' in liver, muscle, islets, and elsewhere may account for many of the features of the metabolic syndrome. Adipose tissue produces many proteins, some of which are inflammatory cytokines, and others of which are antiinflammatory or which improve insulin sensitivity.

SUMMARY

The treatment of obesity requires the identification of the high-risk patient, and the institution of lifestyle measures with a long-term outlook, and an avoidance of heavily marketed fads. Current research will likely lead to improved medications in the future.

The origins of cachexia in acute and chronic inflammatory diseases

The term cachexia originates from the Greek root kakos hexis, which translates into "bad condition," recognized for centuries as a progressive deterioration of body habitus. Cachexia is commonly associated with a number of disease states, including acute inflammatory processes associated with critical illness and chronic inflammatory diseases, such as cancer, congestive heart failure, chronic obstructive pulmonary disease, and human immunodeficiency virus infection. Cachexia is responsible for the deaths of 10%-22% of all patients with cancer and approximately 15% of the trauma deaths that occur from sepsis-induced organ dysfunction and malnutrition days to weeks after the initial traumatic event. The abnormalities associated with cachexia include anorexia, weight loss, a preferential loss of somatic muscle and fat mass, altered hepatic glucose and lipid metabolism, and anemia. Anorexia alone cannot fully explain the development of cachexia; metabolic alterations in carbohydrate, lipid, and protein metabolism contribute to the severe tissue losses. Despite significant advances in our understanding of specific disease processes, the mechanisms leading to cachexia remain unclear and multifactorial. Although complex, increasing evidence from both animal models and clinical studies suggests that an inflammatory response, mediated in part by a dysregulated production of proinflammatory cytokines, plays a role in the genesis of cachexia, associated with both critical illness and chronic inflammatory diseases. These cytokines are further thought to induce an acute phase protein response (APR) and produce the alterations in lipid and carbohydrate metabolism identified as crucial markers of acute inflammation in states of malignancy and critical illness. Although much is still unknown about the etiology of cachexia, there is growing appreciation that cachexia represents the endproduct of an inappropriate interplay between multiple cytokines, neuropeptides, classic stress hormones, and intermediary substrate metabolism.

Fish oils produce anti-inflammatory effects and improve body weight in severe heart failure

BACKGROUND

Fish oils have been shown to reduce production of tumor necrosis factor-alpha (TNF-alpha) in healthy subjects. We sought to evaluate the effects of fish oils on pro-inflammatory cytokines and body weight in patients with advanced heart failure.

METHODS

Fourteen patients (New York Heart Association [NYHA] Class III to IV heart failure) were randomized in a double-blinded trial to active therapy with 8 g of n-3 fatty acids (Group A, n = 7) or placebo (Group B, n = 7) for 18 weeks. TNF-alpha and interleukin-1 (IL-1) production were measured by radioimmunoassay after endotoxin stimulation of peripheral blood mononuclear cells.

RESULTS

Placebo-treated patients had a 44% increase in TNF-alpha (from 1.28 to 1.84 pg/ml; p = 0.07) but no significant change in IL-1 (from 0.68 to 0.78 pg/ml) production. n-3 fatty acids resulted in a 59% reduction in TNF-alpha (from 1.64 to 0.68 pg/ml; p = 0.02) and 39% decrease in IL-1 (from 1.98 to 1.21 pg/ml; p = 0.09) production. There was an inverse correlation between change in TNF-alpha production and change in percent body fat (r = -0.6; p = 0.02).

CONCLUSIONS

Fish oils decrease TNF-alpha production in heart failure and improve body weight. Fish oil therapy may represent a novel therapeutic approach in late-stage heart failure characterized by cardiac cachexia.

Exercise training enhances tumor necrosis factor-alpha-induced expressions of anti-apoptotic genes without alterations in caspase-3 activity in rat epididymal adipocytes

The effect of exercise training on tumor necrosis factor-alpha (TNF-alpha) signaling was investigated in rat epididymal adipocytes. Incubation of isolated adipocytes with TNF-alpha (20 ng/ml) for 5 h enhanced the expression of the inhibitor apoptosis protein 2 (IAP2) gene without any enhancement of caspase-3 activity in both the sedentary control (C) and exercise-trained (TR) groups. However, the ability of TNF-alpha to enhance IAP2 gene expression was significantly greater in TR than in C rats. The basal expression of the IkappaB kinase beta (IKK beta) gene and that of the BCL-x(L) gene were also higher in TR than in C rats. Mn-superoxidedismutase contents in adipocytes were higher in TR than in C rats. Moreover, no apoptotic nucleuses of adipocytes in response to acute exercise were observed in either group at least up to 5 h after exercise. Exercise training also enhanced the inhibitory effect of TNF-alpha on the gene expression of the fatty acid synthase (FAS), a lipogenic enzyme, suggesting that fatty acid synthesis may be reduced. Thus, exercise training enhanced TNF-alpha signaling directed toward the expressions of survival signals and the suppression of FAS gene expression.

Dyslipidemia and inflammation: an evolutionary conserved mechanism

Inflammation leads to changes in lipid metabolism aimed at decreasing the toxicity of a variety of harmful agents and tissue repair by redistributing nutrients to cells involved in host defence. Acute phase response, mediated by cytokines, preserves the host from acute injury. When this inflammation becomes chronic, it might lead to chronic disorders as atherosclerosis and the metabolic syndrome. The activation of the inflammatory cascade will induce a decrease in HDL-cholesterol (HDL-C), with impairment in reverse cholesterol transport, and parallel changes in apolipoproteins, enzymes, anti-oxidant capacity and ATP binding cassette A1-dependent efflux. This decrease in HDL-C and phospholipids could stimulate compensatory changes, as synthesis and accumulation of phospholipid-rich VLDL which binds bacterial products and other toxic substances, resulting in hypertriglyceridemia. The final consequence is an increased accumulation of cholesterol in cells. When the compensatory response (inflammation) is not able to repair injury, it turns into a harmful reaction, and the lipid changes will become chronic, either by repeated or overwhelming stimulus, enhancing the formation of atherosclerotic lesions. Thus, the classical lipid changes associated with the metabolic syndrome (increased triglycerides and decreased HDL-C) may be envisioned as a highly conserved evolutionary response aimed at tissue repair. Under this assumption, the problem is not the response but the persistence of the stimulus.