Increased T-helper interferon-gamma-secreting cells in obese children

Non-alcoholic steatohepatitis in morbidly obese patients

The hepatic complications of morbid obesity range from steatosis to steatohepatitis (Non-alcoholic steatohepatitis [NASH]), fibrosis, cirrhosis and finally hepatocellular carcinoma. The pathophysiological mechanisms of the progression of a normal liver to a liver showing steatosis and then steatohepatitis are complex, including, per se, insulin-resistance, iron accumulation, oxidative stress and hepatocyte death. An imbalance in anti- and pro-inflammatory factors may be the trigger. These factors can originate from intra- or extrahepatic sites, particularly the adipose tissue and the gut. This review will provide insight into the current diagnosis and understanding of hepatic inflammation including non-invasive markers of NASH (markers of hepatocyte death), intrahepatic mechanisms (regulation of the immune and inflammatory response, hepatocellular iron deposition, hepatocyte death) and extrahepatic factors (from adipose tissue and gut) in morbidly obese patients.

The immune system's involvement in obesity-driven type 2 diabetes

Type 2 diabetes is now a worldwide epidemic, strongly correlated with an elevated incidence of obesity. Obesity-associated adipose tissue inflammation is a major cause of the decreased insulin sensitivity seen in type 2 diabetes. Recent studies have shed light on the cross-talk between the immune system and organismal metabolism. This review discusses the connection between inflammation in adipose tissue and systemic insulin resistance, focusing on the roles of innate and adaptive immune cell subsets in the pathogenesis of this metabolic disease.

Review on the impact of pregnancy and obesity on influenza virus infection

A myriad of risk factors have been linked to an increase in the severity of the pandemic H1N1 2009 influenza A virus [A(H1N1)pdm09] including pregnancy and obesity where death rates can be elevated as compared to the general population. The goal of this review is to provide an overview of the influence of pregnancy and obesity on the reported cases of A(H1N1)pdm09 virus infection and of how the concurrent presence of these factors may have an exacerbating effect on infection outcome. Also, the hypothesized immunologic mechanisms that contribute to A(H1N1)pdm09 virus severity during pregnant or obese states are outlined. Identifying the mechanisms underlying the increased disease severity in these populations may result in improved therapeutic approaches and future pandemic preparedness.

Systemic inflammation and insulin sensitivity in obese IFN-γ knockout mice

Adipose tissue macrophages are important mediators of inflammation and insulin resistance in obesity. IFN-γ is a central regulator of macrophage function. The role of IFN-γ in regulating systemic inflammation and insulin resistance in obesity is unknown. We studied obese IFN-γ knockout mice to identify the role of IFN-γ in regulating inflammation and insulin sensitivity in obesity. IFN-γ-knockout C57Bl/6 mice and wild-type control litter mates were maintained on normal chow or a high fat diet for 13 weeks and then underwent insulin sensitivity testing then sacrifice and tissue collection. Flow cytometry, intracellular cytokine staining, and QRTPCR were used to define tissue lymphocyte phenotype and cytokine expression profiles. Adipocyte size was determined from whole adipose tissue explants examined under immunofluorescence microscopy. Diet-induced obesity induced systemic inflammation and insulin resistance, along with a pan-leukocyte adipose tissue infiltrate that includes macrophages, T-cells, and NK cells. Obese IFN-γ-knockout animals, compared with obese wild-type control animals, demonstrate modest improvements in insulin sensitivity, decreased adipocyte size, and an M2-shift in ATM phenotype and cytokine expression. These data suggest a role for IFN-γ in the regulation of inflammation and glucose homeostasis in obesity though multiple potential mechanisms, including effects on adipogenesis, cytokine expression, and macrophage phenotype.

Obesity is associated with activated and insulin resistant immune cells

BACKGROUND

Obesity and type 2 diabetes mellitus are characterized by insulin resistance and 'low-grade inflammation'; however, the pathophysiological link is poorly understood. To determine the relative contribution of obesity and insulin resistance to systemic 'inflammation', this study comprehensively characterized circulating immune cells in different grades of obesity.

METHODS

Immune cell phenotypes and activation status were analysed by flow cytometry cross-sectionally in morbidly obese (n = 16, body mass index (BMI) 42.2 ± 5.4 kg/m2), overweight (n = 13, BMI 27.4 ± 1.6 kg/m2) and normal weight (n = 12, BMI 22.5 ± 1.9 kg/m2) subjects.

RESULTS

Obese, but not overweight subjects, had increased activation marker expression on neutrophils, monocytes, T-lymphocytes and polarization of T helper cells towards a pro-inflammatory type 1-phenotype (Th1). Th1 numbers correlated positively with the degree of insulin resistance (homeostasis model assessment, p < 0.05). Lymphocytes from obese subjects showed reduced insulin-stimulated AKT-phosphorylation in vitro. Supra-physiological insulin concentrations did not affect T-cell differentiation, which under normal circumstances would promote an anti-inflammatory T helper type 2-phenotype.

CONCLUSIONS

These results show that morbid obesity is characterized by circulating immune cells that are activated and insulin resistant, with the T-cell balance polarized towards a pro-inflammatory Th1 phenotype. The loss of insulin-induced suppression of inflammatory phenotypes in circulating immune cells could contribute to the systemic and adipose tissue inflammation found in morbid obesity.

Alzheimer's disease promotion by obesity: induced mechanisms-molecular links and perspectives

The incidence of AD is increasing in parallel with the increase in life expectancy. At the same time the prevalence of metabolic syndrome and obesity is reaching epidemic proportions in western populations. Stress is one of the major inducers of visceral fat and obesity development, underlying accelerated aging processes. Adipose tissue is at present considered as an active endocrine organ, producing important mediators involved in metabolism regulation as well as in inflammatory mechanisms. Insulin and leptin resistance has been related to the dysregulation of energy balance and to the induction of a chronic inflammatory status which have been recognized as important cofactors in cognitive impairment and AD initiation and progression. The aim of this paper is to disclose the correlation between the onset and progression of AD and the stress-induced changes in lifestyle, leading to overnutrition and reduced physical activity, ending with metabolic syndrome and obesity. The involved molecular mechanisms will be briefly discussed, and advisable guide lines for the prevention of AD through lifestyle modifications will be proposed.

Obese Mexican American children have elevated MCP-1, TNF-α, monocyte concentration, and dyslipidemia

BACKGROUND AND OBJECTIVE

Obesity is an independent risk factor for chronic disease. The prevalence of obesity is especially high among Mexican American children. Peripheral blood monocytes are altered with obesity contributing to elevated systemic inflammation and increased risk of chronic disease. In addition, obesity alters the circulating levels of cytokines/chemokines that influence monocyte behavior. The study objective was to investigate alterations in blood monocytes and plasma cytokines/chemokine levels among healthy weight (standardized BMI [zBMI] ≤85th percentile; n = 66), overweight (zBMI 85th-95th percentile; n = 23), and obese (zBMI ≥95th percentile; n = 39) Mexican American children.

METHODS

Blood samples were analyzed for total and subset monocyte concentration via flow cytometry. Serum monocyte chemoattractant protein-1 (MCP-1), fractalkine, interleukin-8, and tumor necrosis factor α (TNF-α) were measured by using a Milliplex MagPix assay. Serum cholesterol, high-density lipoproteins, triglycerides, and glucose were measured by using an enzymatic assay.

RESULTS

Total monocyte concentration (P = .012), classic monocyte concentration (P = .045), MCP-1 (P = .015), and TNF-α (P = .002) were significantly greater in obese children compared with healthy weight children. Also, overweight and obese children had elevated triglycerides (P = .001) and reduced high-density lipoproteins (P = .033) compared with healthy weight children.

CONCLUSIONS

Childhood obesity alters monocytes and circulating chemokines, putting children at a greater risk of developing obesity-related chronic diseases in adulthood. Further characterization of early immune alterations in childhood obesity may provide additional clinical insight into the assessment of obesity-related disease risk.

Dysglycemia induces abnormal circadian blood pressure variability

BACKGROUND

Prediabetes (PreDM) in asymptomatic adults is associated with abnormal circadian blood pressure variability (abnormal CBPV).

HYPOTHESIS

Systemic inflammation and glycemia influence circadian blood pressure variability.

METHODS

Dahl salt-sensitive (S) rats (n = 19) after weaning were fed either an American (AD) or a standard (SD) diet. The AD (high-glycemic-index, high-fat) simulated customary human diet, provided daily overabundant calories which over time lead to body weight gain. The SD (low-glycemic-index, low-fat) mirrored desirable balanced human diet for maintaining body weight. Body weight and serum concentrations for fasting glucose (FG), adipokines (leptin and adiponectin), and proinflammatory cytokines [monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α)] were measured. Rats were surgically implanted with C40 transmitters and blood pressure (BP-both systolic; SBP and diastolic; DBP) and heart rate (HR) were recorded by telemetry every 5 minutes during both sleep (day) and active (night) periods. Pulse pressure (PP) was calculated (PP = SBP-DBP).

RESULTS

[mean(SEM)]: The AD fed group displayed significant increase in body weight (after 90 days; p < 0.01). Fasting glucose, adipokine (leptin and adiponectin) concentrations significantly increased (at 90 and 172 days; all p < 0.05), along with a trend for increased concentrations of systemic pro-inflammatory cytokines (MCP-1 and TNF-α) on day 90. The AD fed group, with significantly higher FG, also exhibited significantly elevated circadian (24-hour) overall mean SBP, DBP, PP and HR (all p < 0.05).

CONCLUSION

These data validate our stated hypothesis that systemic inflammation and glycemia influence circadian blood pressure variability. This study, for the first time, demonstrates a cause and effect relationship between caloric excess, enhanced systemic inflammation, dysglycemia, loss of blood pressure control and abnormal CBPV. Our results provide the fundamental basis for examining the relationship between dysglycemia and perturbation of the underlying mechanisms (adipose tissue dysfunction induced local and systemic inflammation, insulin resistance and alteration of adipose tissue precursors for the renin-aldosterone-angiotensin system) which generate abnormal CBPV.

Relationship of adipokines with immune response and lung function in obese asthmatic and non-asthmatic women

BACKGROUND

Obesity is a risk factor for asthma. Studies in mice suggest that the adipokines leptin and adiponectin affect asthmatic responses. The purpose of this study was to determine if adipokines associated with obesity are (1) altered in obese women with asthma compared to controls and (2) associated with increased cytokines and chemokines involved in allergic inflammation.

METHODS

We performed a cross-sectional study of asthmatic and non-asthmatic obese premenopausal women. Participants answered questionnaires and performed lung function tests. Serum and peripheral blood mononuclear cells (PBMCs) were collected for analysis of cytokines and adipokines.

RESULTS

A total of 22 asthmatic (mean body mass index 40.0 ± 5.1 kg/m(2)) and 20 non-asthmatic women (mean body mass index 41.3 ± 5.6 kg/m(2)) participated. We found no difference in serum adipokine concentrations between asthmatics and non-asthmatics. Serum adiponectin correlated positively with PBMC eotaxin (r(s) = 0.55, p = .0003) and RANTES (regulated upon activation, normal T-cell expressed, and secreted) (r(s) = 0.36, p = .03), whereas serum leptin correlated negatively with PBMC eotaxin (r(s) = -0.34, p = .04). There was a negative correlation between serum adiponectin and PBMC interferon-γ (r(s) = -0.41, p = .01).

CONCLUSIONS

Perturbations of adipokines that occur in obesity were correlated with decreased cytokine production typically associated with allergic responses in PBMC of obese premenopausal women. This study suggests that although obese asthmatics may have elements of Th2-mediated inflammation, adipokine derangements in obesity are associated with Th1 rather than Th2 bias. Obesity has complex effects on allergic inflammation and is likely to be important modifier of the pathogenesis of airway disease in asthma.

Obesity-associated asthma in children: a distinct entity

BACKGROUND

Obesity-associated asthma has been proposed to be a distinct entity, differing in immune pathogenesis from atopic asthma. Both obesity-mediated inflammation and increase in adiposity are potential mechanistic factors that are poorly defined among children. We hypothesized that pediatric obesity-associated asthma would be characterized by T helper (Th) 1, rather than the Th2 polarization associated with atopic asthma. Moreover, we speculated that Th1 biomarkers and anthropometric measures would correlate with pulmonary function tests (PFTs) in obese asthmatic children.

METHODS

We recruited 120 children, with 30 in each of the four study groups: obese asthmatic children, nonobese asthmatic children, obese nonasthmatic children, and nonobese nonasthmatic children. All children underwent pulmonary function testing. Blood was collected for measurement of serum cytokines. T-cell responses to mitogen, phorbol 12-myristate 13-acetate (PMA), or antigens tetanus toxoid or Dermatophagoides farinae were obtained by flow cytometric analysis of intracellular cytokine staining for interferon-γ (IFN-γ) (Th1) or IL-4 (Th2) within the CD4 population.

RESULTS

Obese asthmatic children had significantly higher Th1 responses to PMA (P < .01) and tetanus toxoid (P < .05) and lower Th2 responses to PMA (P < .05) and D farinae (P < .01) compared with nonobese asthmatic children. Th-cell patterns did not differ between obese asthmatic children and obese nonasthmatic children. Obese asthmatic children had lower FEV(1)/FVC (P < .01) and residual volume/total lung capacity ratios (P < .005) compared with the other study groups, which negatively correlated with serum interferon-inducible protein 10 and IFN-γ levels, respectively. PFTs, however, did not correlate with BMI z score or waist to hip ratio.

CONCLUSIONS

We found that pediatric obesity-associated asthma differed from atopic asthma and was characterized by Th1 polarization. The altered immune environment inversely correlated with PFTs in obese asthmatic children.

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

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

Increased levels of both Th1 and Th2 cytokines in subjects with metabolic syndrome (CURES-103)

OBJECTIVE

Metabolic syndrome (MS) is a cluster of metabolic abnormalities associated with obesity, insulin resistance (IR), dyslipidemia, and hypertension in which inflammation plays an important role. Few studies have addressed the role played by T cell-derived cytokines in MS. The aim of the study was to look at the T-helper (Th) 1 (interleukin [IL]-12, IL-2, and interferon-γ [IFN-γ]) and Th2 (IL-4, IL-5, and IL-13) cytokines in MS in the high-risk Asian Indian population.

RESEARCH DESIGN AND METHODS

Study subjects were recruited from the Chennai Urban Rural Epidemiology Study. MS was defined using National Cholesterol Education Program-Adult Treatment Panel III criteria modified for waist according to World Health Organization Asia Pacific guidelines. Serum cytokine profile was determined by multiplex cytokine assay in subjects with (n = 21) and without (n = 33) MS.

RESULTS

Both Th1 and Th2 cytokines showed up-regulation in MS. IL-12 (5.40 pg/mL in MS vs. 3.24 pg/mL in non-MS; P < 0.01), IFN-γ (6.8 pg/mL in MS vs. 4.7 pg/mL in non-MS; P < 0.05), IL-4 (0.61 pg/mL in MS vs. 0.34 pg/mL in non-MS; P < 0.001), IL-5 (4.39 pg/mL in MS vs. 2.36 pg/mL in non-MS; P < 0.001), and IL-13 (3.42 pg in MS vs. 2.72 pg/mL in non-MS; P < 0.01) were significantly increased in subjects with MS compared with those without. Both Th1 and Th2 cytokines showed a significant association with fasting plasma glucose level even after adjusting for age and gender. The Th1 and Th2 cytokines also showed a negative association with adiponectin and a positive association with the homeostasis model of assessment of IR and high-sensitivity C-reactive protein.

CONCLUSIONS

Apart from pro-inflammatory cytokines, Th cytokines might play an important role in inflammation, IR, and MS.

Immunomodulatory effect of water extract of cinnamon on anti-CD3-induced cytokine responses and p38, JNK, ERK1/2, and STAT4 activation

CONTEXT

Cinnamon bark is a very popular herb used in traditional medicine to treat various disorders such as chronic gastric symptoms, arthritis, and the common cold.

OBJECTIVE

The immunomodulatory effect of water extract of cinnamon bark (CWE) on cytokine secretion and involvement of intracellular signaling molecules in activated T cells have been examined.

MATERIALS AND METHODS

Mice were orally administered CWE for 7 days. Serum was obtained 90 min after intravenous injection of anti-CD3 antibody (Ab). Splenocytes were cultured with anti-CD3 Ab and CWE for cytokine expression, cell cycle, apoptotic/necrotic changes, and viability. IκBα, p38, JNK, ERK1/2, STAT4, and STAT6 were analyzed using western blotting.

RESULTS

Administration of CWE decreased systemic levels of IFN-γ, but not the levels of IL-4 or IL-2. In vitro, CWE inhibited anti-CD3 Ab-stimulated IFN-γ and IL-4 at the mRNA and secreted protein levels. Despite its inhibition of IL-2 transcript, CWE enhanced IL-2 secretion. CWE treatment caused a reduction in the sub-G1 phase, accompanied by an increased ratio of apoptotic cells to necrotic cells. The increased IL-2 secretion by CWE was not mediated by its direct effect on CD4 T cells. CWE inhibited the activation of p38, JNK, ERK1/2, and STAT4, but not IκBα degradation or STAT6.

DISCUSSION AND CONCLUSIONS

These observations provided evidence that CWE was able to down-regulate IFN-γ expression in activated T cells without altering IL-2 production, involving inhibition of p38, JNK, ERK1/2, and STAT4. Our results contribute to a better understanding of the immunomodulatory action of cinnamon bark for the application of inflammatory disorders.

Interferon-gamma-inducible kynurenines/pteridines inflammation cascade: implications for aging and aging-associated psychiatric and medical disorders

This review of literature and our data suggests that up-regulated production of interferon-gamma (IFNG) in periphery and brain triggers a merger of tryptophan (TRY)-kynurenine (KYN) and guanine-tetrahydrobiopterin (BH4) metabolic pathways into inflammation cascade involved in aging and aging-associated medical and psychiatric disorders (AAMPD) (metabolic syndrome, depression, vascular cognitive impairment). IFNG-inducible KYN/pteridines inflammation cascade is characterized by up-regulation of nitric oxide synthase (NOS) activity (induced by KYN) and decreased formation of NOS cofactor, BH4, that results in uncoupling of NOS that shifting arginine from NO to superoxide anion production. Superoxide anion and free radicals among KYN derivatives trigger phospholipase A2-arachidonic acid cascade associated with AAMPD. IFNG-induced up-regulation of indoleamine 2,3-dioxygenase (IDO), rate-limiting enzyme of TRY-KYN pathway, decreases TRY conversion into serotonin (substrate of antidepressant effect) and increases production of KYN associated with diabetes [xanthurenic acid (XA)], anxiety (KYN), psychoses and cognitive impairment (kynurenic acid). IFNG-inducible KYN/pteridines inflammation cascade is impacted by IFNG (+874) T/A genotypes, encoding cytokine production. In addition to literature data on KYN/TRY ratio (IDO activity index), we observe neopterin levels (index of activity of rate-limiting enzyme of guanine-BH4 pathway) to be higher in carriers of high (T) than of low (A) producers alleles; and to correlate with AAMPD markers (e.g., insulin resistance, body mass index, mortality risk), and with IFN-alpha-induced depression in hepatitis C patients. IFNG-inducible cascade is influenced by environmental factors (e.g., vitamin B6 deficiency increases XA formation) and by pharmacological agents; and might offer new approaches for anti-aging and anti-AAMPD interventions.

Emerging role of adipokines as mediators in atherosclerosis

Atherosclerotic cardiovascular disease is a major health problem around the world. Obesity is a primary risk factor for atherosclerosis and is associated with increased morbidity and mortality of cardiovascular diseases. However, the precise molecular pathways underlying this close association remain poorly understood. Adipokines are cytokines, chemokines and hormones secreted by adipose tissue that couple the regulation of lipid accumulation, inflammation, and atherogenesis, and therefore serve to link obesity with cardiovascular disorders. Obesity-related disorders including metabolic syndrome, diabetes, atherosclerosis, hypertension, and coronary artery disease are associated with dysregulated adipokine(s) expression. Recent studies demonstrate the proinflammatory effects as well as atherogenic properties of adipokines. Adipokines also participate in the regulation of endothelial function, which is an early event in atherosclerosis. By contrast, adiponectin, an adipocyte-derived hormone, exerts anti-inflammatory, anti-atherogenic and vascular protective effects. Furthermore, there is an interactive association among adipokines, by which adipokines reciprocally regulate each other's expression. Understanding this interplay may reveal plausible mechanisms for treating atherosclerosis and coronary heart disease by modulating adipokine(s) expression. In this review, we discuss insights into the role and the therapeutic potential of adipokines as mediators of atherosclerosis.

Functional and morphological vascular changes in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has been consistently found to be associated with features of the metabolic syndrome (MS), a condition carrying a high risk of cardiovascular events. The present study aimed to determine whether, in children and adolescents, NAFLD is atherogenic beyond its association with MS and its components. We assessed both flow-mediated dilation of the brachial artery (FMD) and carotid intima-media thickness (cIMT), along with lipid profile, glucose, insulin, insulin resistance, and high-sensitivity C-reactive protein (CRPHS), in 250 obese children, 100 with and 150 without NAFLD, and 150 healthy normal-weight children. NAFLD was diagnosed by ultrasound examination and persistently elevated alanine aminotransferase, after exclusion of infectious and metabolic disorders. Compared to controls and children without liver involvement, those with ultrasound-diagnosed NAFLD (and elevated alanine aminotransferase) demonstrated significantly impaired FMD and increased cIMT. Patients with NAFLD had more features of MS and elevated CRPHS levels. In addition, percent FMD was remarkably reduced, whereas cIMT was increased in obese children with MS compared to those without MS. Using logistic regression analysis, the presence of NAFLD was found to be an independent predictor of low percent FMD (odds ratio, 2.25 [95% confidence interval, 1.29 to 3.92]; P = 0.004) as well as of increased cIMT (1.98 [1.16 to 3.36]; P = 0.031), after adjustment for age, gender, Tanner stage, and presence of MS. When we analyzed the relations between cIMT and measures of FMD in patients with NAFLD, the disease was associated with increased cIMT in children with impaired FMD status.

CONCLUSION

The presence of liver disease entails more severe functional and anatomic changes in the arterial wall. Its detection may help identify individuals with increased cardiometabolic risk.

Adaptive immunity and adipose tissue biology

Studies of immunity typically focus on understanding how hematopoietic cells interact within conventional secondary lymphoid tissues. However, immune reactions and their regulation occur in various environments within the body. Adipose tissue is one tissue that can influence and be influenced by adjacent and embedded lymphocytes. Despite the abundance and wide distribution of such tissue, and despite a growing obesity epidemic, studies of these interactions have been only marginally appreciated in the past. Here, we review advances in understanding of lymphoid structures within adipose tissue, the relationship between adipose tissue and adaptive immune function, and evidence for how this relationship contributes to obesity-associated diseases.

Hepatic expression patterns of inflammatory and immune response genes associated with obesity and NASH in morbidly obese patients

BACKGROUND

Obesity modulates inflammation and activation of immune pathways which can lead to liver complications. We aimed at identifying expression patterns of inflammatory and immune response genes specifically associated with obesity and NASH in the liver of morbidly obese patients.

METHODOLOGY/PRINCIPAL FINDINGS

Expression of 222 genes was evaluated by quantitative RT-PCR in the liver of morbidly obese patients with histologically normal liver (n = 6), or with severe steatosis without (n = 6) or with NASH (n = 6), and in lean controls (n = 5). Hepatic expression of 58 out of 222 inflammatory and immune response genes was upregulated in NASH patients. The most notable changes occurred in genes encoding chemokines and chemokine receptors involved in leukocyte recruitment, CD and cytokines involved in the T cell activation towards a Th1 phenotype, and immune semaphorins. This regulation seems to be specific for the liver since visceral adipose tissue expression and serum levels of MCP1, IP10, TNFα and IL6 were not modified. Importantly, 47 other genes were already upregulated in histologically normal liver (e.g. CRP, Toll-like receptor (TLR) pathway). Interestingly, serum palmitate, known to activate the TLR pathway, was increased with steatosis.

CONCLUSION/SIGNIFICANCE

The liver of obese patients without histological abnormalities already displayed a low-grade inflammation and could be more responsive to activators of the TLR pathway. NASH was then characterized by a specific gene signature. These findings help to identify new potential actors of the pathogenesis of NAFLD.

Short-term overfeeding may induce peripheral insulin resistance without altering subcutaneous adipose tissue macrophages in humans

OBJECTIVE

Chronic low-grade inflammation is a feature of obesity and is postulated to be causal in the development of insulin resistance and type 2 diabetes. The aim of this study was to assess whether overfeeding induces peripheral insulin resistance in lean and overweight humans, and, if so, whether it is associated with increased systemic and adipose tissue inflammation.

RESEARCH DESIGN AND METHODS

Thirty-six healthy individuals undertook 28 days of overfeeding by +1,250 kcal/day (45% fat). Weight, body composition, insulin sensitivity (hyperinsulinemic-euglycemic clamp), serum and gene expression of inflammation markers, immune cell activation, fat cell size, macrophage and T-cell numbers in abdominal subcutaneous adipose tissue (flow cytometry and immunohistochemistry) were assessed at baseline and after 28 days.

RESULTS

Subjects gained 2.7 +/- 1.6 kg (P < 0.001) and increased fat mass by 1.1 +/- 1.6% (P < 0.001). Insulin sensitivity decreased by 11% from 54.6 +/- 18.7 to 48.9 +/- 15.7 micromol/(kg of FFM)/min (P = 0.01). There was a significant increase in circulating C-reactive protein (P = 0.002) and monocyte chemoattractant protein-1 (P = 0.01), but no change in interleukin-6 and intercellular adhesion molecule-1. There were no changes in fat cell size, the number of adipose tissue macrophages or T-cells, or inflammatory gene expression and no change in circulating immune cell number or expression of their surface activation markers after overfeeding.

CONCLUSIONS

Weight gain-induced insulin resistance was observed in the absence of a significant inflammatory state, suggesting that inflammation in subcutaneous adipose tissue occurs subsequent to peripheral insulin resistance in humans.

The effects of weight loss and gastric banding on the innate and adaptive immune system in type 2 diabetes and prediabetes

CONTEXT

Obesity-related chronic inflammation is implicated in the pathogenesis of type 2 diabetes (T2D).

OBJECTIVE

The objective of the study was to determine the effects of weight loss on immune cells in T2D and prediabetes.

DESIGN AND SETTING

Thirteen obese subjects with T2D or prediabetes underwent 24 wk dietary energy restriction with gastric banding surgery at 12 wk.

MAIN OUTCOME MEASURES

Measures included weight, waist, and insulin resistance; surface activation marker expression on circulating immune cells; T-helper cell polarization: type 1 (Th1), type 2 (Th2); adipose tissue macrophage number and activation in sc and visceral adipose tissue.

RESULTS

Mean total weight loss was 13.5%. There were significant decreases in expression of proinflammatory activation markers: granulocyte CD11b, monocyte CD66b, and T cell CD69 and CD25. Proinflammatory Th1 cell numbers fell by greater than 80%, as did the Th1 to Th2 ratio. The fall in Th1 to Th2 ratio related to weight (P < 0.05) and waist loss (P < 0.05). Reduction in immune cell activation was more pronounced in subjects with prediabetes. Weight and abdominal fat loss were predicted by lower activation of adipose tissue macrophage in sc and visceral adipose tissue (P < 0.05).

CONCLUSIONS

Energy restriction before and after gastric banding attenuates activation of circulating immune cells of the innate and adaptive immune system in T2D and prediabetes. The role of immune cells in the chronic inflammation of obesity and T2D requires further investigation.

Obesity, airway hyperresponsiveness, and inflammation

Epidemiological data indicate that obesity is a risk factor for asthma, but the mechanistic basis for this relationship is not established. Here we review data from human subjects and animal models investigating the relationship between obesity and airway hyperresponsiveness, a characteristic feature of asthma. We discuss obesity as a state of chronic systemic inflammation resulting from interactions between adipocytes and adipose tissue macrophages that are recruited to obese adipose tissue. Finally, we focus on the possibility that aspects of this inflammation, particularly obesity-related changes in TNF-alpha, leptin, and adiponectin, may contribute to airway hyperresponsiveness in obesity. Determining how obesity promotes asthma may uncover novel therapeutic strategies that are effective in the obese asthmatic subject.

Obesity, airway hyperresponsiveness, and inflammation

Epidemiological data indicate that obesity is a risk factor for asthma, but the mechanistic basis for this relationship is not established. Here we review data from human subjects and animal models investigating the relationship between obesity and airway hyperresponsiveness, a characteristic feature of asthma. We discuss obesity as a state of chronic systemic inflammation resulting from interactions between adipocytes and adipose tissue macrophages that are recruited to obese adipose tissue. Finally, we focus on the possibility that aspects of this inflammation, particularly obesity-related changes in TNF-alpha, leptin, and adiponectin, may contribute to airway hyperresponsiveness in obesity. Determining how obesity promotes asthma may uncover novel therapeutic strategies that are effective in the obese asthmatic subject.

Interferon-gamma bolsters CD95/Fas-mediated apoptosis of astroglioma cells

In the present study, we investigated the mechanisms of the resistance to CD95-mediated cell death and the effects of interferon-gamma in modulating the susceptibility to CD95-induced apoptosis of human astroglioma cells. We found that interferon-gamma administration sensitized cancer cells to CD95-mediated apoptosis. The mechanism underlying this sensitization appeared to be associated with a framework of cell changes, including up-regulation of death receptor at the cell surface, pro-apoptotic molecule Bax and Bak over-expression and mitochondria hyperpolarization, as is known to be associated with cell sensitization to apoptosis. An involvement of the proteasome activity in the mechanism of sensitization by interferon-gamma was also detected, probably as a result of the differing expression of catalytic proteasome subunits. Taken together, these findings suggest that interferon-gamma could represent a promising candidate for modulating astroglioma cell apoptotic susceptibility.

Human apolipoprotein D overexpression in transgenic mice induces insulin resistance and alters lipid metabolism

Apolipoprotein D (apoD), a widely expressed lipocalin, has the capacity to transport small hydrophobic molecules. Although it has been proposed that apoD may have multiple tissue-specific, physiological ligands and functions, these have yet to be identified. To gain insight in some of its functions, we generated transgenic mice overexpressing human apoD (H-apoD) under the control of neuron-specific promoters. In Thy-1/apoD and NSE/apoD mice, expression of H-apoD was strong in the nervous system although weakly detected in peripheral organs such as the liver and blood cells. These mice displayed not entirely anticipated metabolic defects. Although they are not obese and have normal lipid concentration in circulation, Thy-1/apoD and NSE/apoD mice are glucose intolerant, insulin resistant, and develop hepatic steatosis. The steatosis and its associated insulin resistance are correlated with impairments in hepatic lipogenesis. However, they are not strongly related with inflammation. This impaired insulin response is not caused by a decrease in circulating leptin or a modulation of adiponectin and resistin levels. These results suggest that variations in the levels and/or sites of apoD expression influence the lipid and glucose metabolism, consolidating apoD as a target for insulin-resistance-related disorders.

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.

Feeding long-chain n-3 polyunsaturated fatty acids to obese leptin receptor-deficient JCR:LA- cp rats modifies immune function and lipid-raft fatty acid composition

Dietary EPA and DHA modulate immunity and thereby may improve the aberrant immune function in obese states. To determine the effects of feeding fish oil (FO) containing EPA and DHA on splenocyte phospholipid (PL) and lipid-raft fatty acid composition, phenotypes and cytokine production, 14-week-old obese, leptin receptor-deficient JCR:LA-cp rats (cp/cp; n 10) were randomised to one of three nutritionally adequate diets for 3 weeks: control (Ctl, 0 % EPA+DHA); low FO (LFO, 0.8 % (w/w) EPA+DHA); high FO (HFO, 1.4 % (w/w) EPA+DHA). Lean JCR:LA-cp (+/ - or +/+) rats (n 5) were fed the Ctl diet. Obese Ctl rats had a higher proportion of n-3 PUFA in splenocyte PL than lean rats fed the same diet (P < 0.05). The lower n-6:n-3 PUFA ratio of splenocyte PL was consistent with the lower mitogen-stimulated interferon (IFN)-gamma and IL-1beta production by cells from obese rats (P < 0.05). Obese rats fed the FO diet had lower mitogen-stimulated Th1 (IFN-gamma) and Th2 (IL-4) cytokine responses, but IL-2 production (concanavalin A; ConA) did not differ (P < 0.05). The HFO diet was more effective in lowering IL-1beta and increasing IL-10 production (ConA, P < 0.05). This lower IL-1beta production was accompanied by a lower proportion of major histocompatability complex class II-positive cells and a higher incorporation of DHA into lipid rafts. This is the first study to demonstrate impaired responses to mitogen stimulation and altered fatty acid incorporation into the membrane PL of JCR:LA-cp rats. Feeding FO lowered the ex vivo inflammatory response, without altering IL-2 production from ConA-stimulated splenocytes which may occur independent of leptin signalling.

Increased activity of interleukin-23/interleukin-17 proinflammatory axis in obese women

OBJECTIVE

To compare the concentrations of cytokines belonging to Th17 axis (interleukin (IL)-17 and IL-23) and Th1 axis (IL-12 and interferon (IFN)-gamma) in obese and lean women, and to investigate their relationships with the proinflammatory adipokine leptin, proinflammatory cytokine macrophage migration inhibitory factor (MIF) and anthropometric and metabolic parameters of obesity.

DESIGN

Cross-sectional study.

SUBJECTS

Twenty-six obese women (age 20-52 years, body mass index (BMI): 30-48 kg/m(2)) and 20 healthy lean women (age 23-46 years, BMI: 18-25 kg/m(2)).

MEASUREMENTS

Plasma levels of cytokines and leptin, BMI, waist circumference (WC) and insulin resistance index HOMA (homeostatic model assessment).

RESULTS

Blood concentrations of IL-17, IL-23, MIF and leptin, but not IL-12 or IFN-gamma, were higher in obese compared with lean women (P=0.002, 0.046, 0.006 and 0.002, respectively). There was a positive correlation between IL-17 and IL-23 (r(s)=0.530), which was at the border of statistical significance (P=0.065). Neither IL-17 nor IL-23 correlated with leptin or MIF, and there was no association between IL-17 and IL-23 levels with BMI, WC or HOMA index.

CONCLUSION

Interleukin-23/IL-17 axis is stimulated in obese women independently of the increase in abdominal fat, insulin resistance, leptin and MIF levels.

Serum leptin and adiponectin levels and their association with allergic sensitization

BACKGROUND

Obesity and respiratory allergies have increased in parallel in industrialized countries. We have recently shown an association between obesity and allergic sensitization whereby obesity diminished the protective effect of childhood farm contact.

OBJECTIVE

To assess whether taking obesity into account allergic sensitization is associated with adipokine levels in blood and whether this effect is modified by childhood farm contact.

METHODS

Serum samples of 231 adult participants (age 18-45 years) of the Lower Saxony Lung Study were analysed for leptin and adiponectin by ELISA. Subjects were elected to represent equal-sized groups with respect to obesity (<30 vs> or =30 kg/m(2)), childhood farm contact, specific IgE to ubiquitous allergens and sex. Multiple logistic regression models were adjusted for potential confounders.

RESULTS

Leptin levels were positively related to the prevalence of sensitization (highest vs lowest quartile odds ratio 6.7, 95% confidence interval 2.0-22.4). For adiponectin levels, a weak, not statistically significant inverse association with sensitization was shown (highest vs lowest quartile 0.4, 0.2-1.1). The association between leptin and sensitization appeared to be more pronounced in subjects with farm contact; however, the effect modification was not statistically significant.

CONCLUSION

These findings suggest that adipokines might be involved in the causal pathway between obesity and allergic sensitization.

Alteration of T helper cells in rats with non-alcoholic fatty liver disease

AIM: To detect tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-4 (IL-4) and forkhead/winged helix transcription factor p3 (Foxp3) gene expression of fatty liver rats under high fat diet and to explore the role of Th1/Th2 balance and Treg in non-alcoholic fatty liver disease (NAFLD).

METHODS: Sprague-Dawley rats, after one-week normal diet, were randomly divided into two groups: the normal group (treated with normal diet, n = 20) and the high fat diet group (treated with high fat diet, n = 20). The rats were all killed at the eighth and sixteenth week, respectively. TNF-a, IFN-γ, IL-4 and Foxp3 gene expression were detected using real time PCR and pathological changes in liver tissues were recorded.

RESULTS: After high fat diet for 8 weeks, liver became remarkably steatotic, but without significant inflammatory changes. IFN-γ mRNA and IL-4 mRNA had no significant change compared with the normal group, and TNF-α mRNA increased slightly but without statistical significance. The ct value of Foxp3 mRNA was significantly higher than normal (26.12 ± 0.69 vs 24.22 ± 0.62, P < 0.05). After high fat diet for 16 weeks, severe fatty liver, inflammatory cell infiltration and hepatocyte necrosis were observed in high fat diet rats. Both of IFN-γ mRNA and TNF-α mRNA were increased significantly (ct value: 24.52 ± 0.87 vs 29.94 ± 1.44, 24.31 ± 1.13 vs 28.88 ± 1.95, both P < 0.05). IL-4 mRNA was not significantly different from the normal group. Foxp3 mRNA was decreased significantly compared with both normal group and high fat diet group at wk 8 (ct value: 32.57 ± 1.54 vs 24.29 ± 1.08, 26.12 ± 0.69, both P < 0.05).

CONCLUSION: Decreased expression of Foxp3 mRNA and Treg in rat livers may play a key role in development of NAFLD. The combined effect of IFN-γ and TNF-α aggravates liver inflammatory injury.

Nonalcoholic fatty liver disease and carotid atherosclerosis in children

Nonalcoholic fatty liver disease (NAFLD) is closely associated with several metabolic syndrome features, including obesity, dyslipidemia, insulin resistance, and increased cardiovascular risk. The present study was undertaken to assess whether NAFLD in children is associated with increased carotid artery intima-media thickness (IMT), a marker of early-generalized atherosclerosis. We analyzed carotid IMT along with serum triglycerides, total, low-density lipoprotein and high-density lipoprotein cholesterol, glucose, insulin, insulin resistance index (as homeostasis model assessment of insulin resistance), aminotransferases, leptin, and adiponectin in 29 obese children with NAFLD, 33 obese children without liver involvement, and 30 control children. The diagnosis and severity of NAFLD was based on ultrasound scan, after exclusion of infectious and metabolic disorders. Obese children with NAFLD had significantly increased carotid IMT [mean 0.58 (95% confidence intervals 0.54-0.62 mm)] than obese children without liver involvement [0.49 (0.46-0.52) mm; p = 0.001] and control children [0.40 (0.36-0.43) mm; p < 0.0005]. In a stepwise multiple regression model, after adjusting for age, gender, Tanner stage, and cardiovascular risk factors, the severity of fatty liver was significantly associated with maximum IMT (b = 0.08; p < 0.0005). Our results suggest that NAFLD is strongly associated with carotid atherosclerosis even in childhood.

Fetal responses during placental malaria modify the risk of low birth weight

Inflammation during placental malaria (PM) is associated with low birth weight (LBW), especially during the first pregnancy, but the relative contribution of maternal or fetal factors that mediate this effect remains unclear and the role of gamma interferon (IFN-gamma) has been controversial. We examined the relationship of maternal and cord plasma levels of IFN-gamma, tumor necrosis factor alpha, interleukin-10, ferritin, and leptin to birth weight for Tanzanian women delivering in an area where there is a high rate of malaria transmission. The placental levels of inflammatory cytokines, including IFN-gamma, increased significantly during PM in primigravid and multigravid women but not in secundigravid women. PM also increased maternal peripheral levels of all inflammatory markers except IFN-gamma but had strikingly little effect on cord levels of these proteins. In a multivariate analysis, placental IFN-gamma was negatively associated (P = 0.01) and cord ferritin was positively associated (P < 0.0001) with birth weight in infected (PM-positive [PM+]) first-time mothers. This relationship was not observed in other mothers, consistent with the epidemiology of PM and disease. Cord leptin had a strong positive relationship with birth weight in offspring of PM-negative women (P = 0.02 to P < 0.0001) but not in offspring of PM+ women (all differences were not significant) in the three gravidity groups. The results confirmed that placental IFN-gamma is related to LBW due to PM during first pregnancies and suggest that fetal ferritin plays a protective role. Because fetal cells are a source of placental IFN-gamma and cord ferritin, the fetal response to PM may modify the risk of LBW.

Diet-induced obese mice have increased mortality and altered immune responses when infected with influenza virus

Obesity is associated with an impaired immune response, an increased susceptibility to bacterial infection, and a chronic increase in proinflammatory cytokines such as IL-6 and TNFalpha. However, few studies have examined the effect of obesity on the immune response to viral infections. Because infection with influenza is a leading cause of morbidity and mortality worldwide, we investigated the effect of obesity on early immune responses to influenza virus exposure. Diet-induced obese and lean control C57BL/6 mice were infected with influenza A/PR8/34, and lung pathology and immune responses were examined at d 0 (uninfected), 3, and 6, postinfection. Following infection, diet-induced obese mice had a significantly higher mortality rate than the lean controls and elevated lung pathology. Antiviral and proinflammatory cytokine mRNA production in the lungs of the infected mice was markedly different between obese and lean mice. IFNalpha and beta were only minimally expressed in the infected lungs of obese mice and there was a notable delay in expression of the proinflammatory cytokines IL-6 and TNFalpha. Additionally, obese mice had a substantial reduction in NK cell cytotoxicity. These data indicate that obesity inhibits the ability of the immune system to appropriately respond to influenza infection and suggests that obesity may lead to increased morbidity and mortality from viral infections.