The central roles of obesity-associated dyslipidaemia, endothelial activation and cytokines in the Metabolic Syndrome--an analysis by structural equation modelling

Hostility is related to clusters of T-cell cytokines and chemokines in healthy men

Hostility is a risk factor for adverse health outcomes as diverse as cardiovascular disease and post-traumatic stress disorder (PTSD). Cytokines have been suggested to mediate this relationship. We investigated whether in healthy men a relation existed between hostility and T-cell mitogen-induced cytokines and chemokines. Male Dutch military personnel (n=304) were included before deployment. Eleven cytokines and chemokines were measured in supernatants of T-cell mitogen-stimulated whole blood cultures by multiplex immunoassay. Factor analysis was used to identify clusters of cytokines and chemokines. In a regression analysis hostility was related to the cytokine/chemokine clusters, and the potential risk factors age, BMI, smoking, drinking, previous deployment, early life trauma and depression. Explorative factor analysis showed four functional clusters; a pro-inflammatory factor (IL-2, TNFalpha, IFNgamma), an anti-inflammatory factor (IL-4, IL-5, IL-10), IL-6/chemokine factor (IL-6, MCP-1, RANTES, IP-10), and MIF. Hostility was significantly related to decreased IL-6/chemokine secretion and increased pro- and anti-inflammatory cytokines. There was an inverse relation between age and hostility scores. Early life trauma and depression were positively and independently related to hostility as well. This study represents a novel way of investigating the relation between cytokines and psychological characteristics. Cytokines/chemokines clustered into functional factors, which were related to hostility in healthy males. Moreover this relation appeared to be independent of reported depression and early trauma.

Hydrogenated fat diet intake during pregnancy and lactation modifies the PAI-1 gene expression in white adipose tissue of offspring in adult life

We examine whether feeding pregnant and lactating rats hydrogenated fats rich in trans fatty acids modifies the plasma lipid profiles and the expression of adipokines involved with insulin resistance and cardiovascular disease in their 90-day-old offspring. Pregnant and lactating Wistar rats were fed with either a control diet (C group) or one enriched with hydrogenated vegetable fat (T group). Upon weaning, the male pups were sorted into four groups: CC, mothers were receiving C and pups were kept on C; CT, mothers were receiving C and pups were fed with T; TT, mothers were receiving T and pups were kept on T; TC, mothers were receiving T and pups were fed with C. Pups' food intake and body weight were quantified weekly and the pups were killed at day 90 of life by decapitation. Blood and carcass as well as retroperitoneal, epididymal, and subcutaneous white adipose tissues were collected. Food intake and body weight were lower in TC and TT, and metabolic efficiency was reduced in TT. Offspring of TT and TC rats had increased white adipose tissue PAI-1 gene expression. Insulin receptor was higher in TT than other groups. Ingestion of hydrogenated vegetable fat by the mother during gestation and lactation could promote deleterious consequences, even after the withdrawal of the causal factor.

The epidemiology of obesity: the size of the problem

The epidemic of obesity took off from about 1980 and in almost all countries has been rising inexorably ever since. Only in 1997 did WHO accept that this was a major public health problem and, even then, there was no accepted method for monitoring the problem in children. It was soon evident, however, that the optimum population body mass index is about 21 and this is particularly true in Asia and Latin America where the populations are very prone to developing abdominal obesity, type 2 diabetes and hypertension. These features are now being increasingly linked to epigenetic programming of gene expression and body composition in utero and early childhood, both in terms of fat/lean tissue ratios and also in terms of organ size and metabolic pathway regulation. New Indian evidence suggests that insulin resistance at birth seems linked to low birth weight and a higher proportion of body fat with selective B12 deficiency and abnormalities of one carbon pool metabolism potentially responsible and affecting 75% of Indians and many populations in the developing world. Biologically there are also adaptive biological mechanisms which limit weight loss after weight gain and thereby in part account for the continuing epidemic despite the widespread desire to slim. Logically, the burden of disease induced by inappropriate diets and widespread physical inactivity can be addressed by increasing physical activity (PA), but simply advocating more leisure time activity is unrealistic. Substantial changes in urban planning and diet are needed to counter the removal of any every day need for PA and the decades of misdirected food policies which with free market forces have induced our current 'toxic environment'. Counteracting this requires unusual policy initiatives.

Association between tumor necrosis factor (TNF)-alpha G-308A gene polymorphism and preeclampsia complicated by severe fetal growth restriction

BACKGROUND

Preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome are multifactorial disorders with genetic and environmental components. Given that the tumor necrosis factor (TNF)-alpha G-308A single nucleotide polymorphism (SNP) affects TNF-alpha gene transcription and that preeclampsia and HELLP syndrome are characterized by a shift towards a Th1-type maternal immune response with increased TNF-alpha production, the aim of the current study was to investigate whether this SNP is associated with preeclampsia and HELLP syndrome in a Caucasian population from Hungary. Additionally, we aimed to examine whether TNF-alpha G-308A polymorphism can influence the risk for fetal growth restriction in preeclamptic patients, which issue none of the earlier studies dealt with.

METHODS

In a case-control study, we analyzed blood samples from 140 preeclamptic patients, 69 patients with HELLP syndrome and 144 normotensive, healthy pregnant women using the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. We performed also a meta-analysis with our results and those of 8 previously published studies.

RESULTS

There were no significant differences in the genotype and allele frequencies of the TNF-alpha G-308A polymorphism between preeclamptic patients and normotensive, healthy pregnant women. However, the mutant (TNF2 or A) allele occurred significantly more frequently in preeclamptic patients with IUGR than in those without IUGR (18.5% versus 7.1%, p=0.003). In addition, the frequency of the mutant allele carriers was significantly higher among preeclamptic patients with IUGR compared to those without IUGR (30.6% versus 12.8%, p=0.010). The mutant allele carriers were found to have an increased risk of severe IUGR-complicated preeclampsia, which was independent of maternal age, prepregnancy BMI and primiparity (odds ratio (OR): 2.89, 95% confidence interval (CI): 1.16-7.22, p=0.023; adjusted OR: 2.78, 95% CI: 1.04-7.45, p=0.042). Nevertheless, no significant differences were detected in the genotype and allele frequencies of the TNF-alpha G-308A polymorphism between patients with HELLP syndrome and control subjects. In the meta-analysis, no association was observed between this SNP and preeclampsia (summary OR: 0.956, 95% CI: 0.693-1.319).

CONCLUSIONS

Although the meta-analysis demonstrated a lack of an overall association between TNF-alpha G-308A polymorphism and preeclampsia, our results suggest a role of this SNP in the risk of severe IUGR-complicated preeclampsia. However, further studies are required with a larger sample size to confirm our findings.

Structural equation modeling of sleep apnea, inflammation, and metabolic dysfunction in children

Obstructive sleep apnea (OSA), often concomitant with obesity, increases the risk for the metabolic syndrome. One mechanism that may participate in this association is upregulation of inflammatory pathways. We used structural equation modeling to assess the interrelations between childhood obesity, OSA, inflammation, and metabolic dysfunction. One hundred and eighty-four children (127 boys, mean age: 8.5 +/- 4.1 years) had height and weight measured, underwent overnight polysomnography and had fasting blood taken. The blood was analyzed for insulin, glucose, lipids, leptin, and cytokines [interferon (IFN)-gamma, granulocyte macrophage-colony stimulating factor, interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor-alpha]. Structural equation modeling (SEM) was used to evaluate associations between the outcomes of interest including hypoxia, arousal (related to respiratory and spontaneous), obesity, metabolic dysfunction, and inflammatory markers. Two cytokine factors and one metabolic factor were derived for the SEM. These factors provided good fit in the structural equation model (chi(2)/df = 2.855; comparative fit index = 0.90, root mean squared error of approximation = 0.10) and all factor loadings were significantly different from zero (P < or = 0.01). Overall, our results indicate that while obesity (as measured by body mass index z-score) has a major influence on the metabolic dysfunction associated with OSA, arousal indices, and cytokine markers may also influence this association. Our results support the hypothesis that OSA is a contributor to the mechanisms that link sleep, systemic inflammation and insulin resistance, and show that the interrelations may begin in childhood.

A guide to modern statistical analysis of immunological data

BACKGROUND

The number of subjects that can be recruited in immunological studies and the number of immunological parameters that can be measured has increased rapidly over the past decade and is likely to continue to expand. Large and complex immunological datasets can now be used to investigate complex scientific questions, but to make the most of the potential in such data and to get the right answers sophisticated statistical approaches are necessary. Such approaches are used in many other scientific disciplines, but immunological studies on the whole still use simple statistical techniques for data analysis.

RESULTS

The paper provides an overview of the range of statistical methods that can be used to answer different immunological study questions. We discuss specific aspects of immunological studies and give examples of typical scientific questions related to immunological data. We review classical bivariate and multivariate statistical techniques (factor analysis, cluster analysis, discriminant analysis) and more advanced methods aimed to explore causal relationships (path analysis/structural equation modelling) and illustrate their application to immunological data. We show the main features of each method, the type of study question they can answer, the type of data they can be applied to, the assumptions required for each method and the software that can be used.

CONCLUSION

This paper will help the immunologist to choose the correct statistical approach for a particular research question.

Implications of increased weight and waist circumference on vascular risk in an older Chinese population: the Guangzhou Biobank Cohort Study

BACKGROUND

The relationships between weight and waist on vascular risk are well described, but the long-term impact of these parameters is less clearly defined, particularly in Chinese populations.

METHODS

Ten thousand four hundred and ten older subjects (50-85 years) were recruited and blood pressure, anthropometric, and fasting vascular risk factors measured. Socioeconomic and demographic data, including self-reported weight and waist gain since 18 years. The association of weight and waist gain with these vascular risk factors was analysed.

RESULTS

Weight, and particularly waist gain were associated with a more adverse vascular risk factor profile, with the most adverse profile associated with gains in both weight and waist. Anthropometric gains were associated with increased risk even in non-obese subjects (p<0.05). Even after adjustment for a range of demographic and socioeconomic factors, waist gain was associated with additional risk of having the metabolic syndrome and its components and self-reported vascular disease in those centrally obese subjects (p<0.05 for all).

CONCLUSION

Increased weight and waist increased the level of vascular risk factors and self-reported disease in both non-obese and obese subjects. The high prevalence of vascular risk factors in this population forewarns of a major developing health burden in the rapidly modernising 1.2 billion Chinese population.

Components of metabolic syndrome predicting diabetes: no role of inflammation or dyslipidemia

OBJECTIVE

The diagnostic criteria and the clinical usefulness of the metabolic syndrome (MetSy) are currently questioned. The objective was to describe the structure of MetSy and to evaluate its components for prediction of diabetes type 2 (T2DM).

RESEARCH METHODS AND PROCEDURES

This was a case-referent study nested within a population-based health survey. Among 33,336 participants, we identified 177 initially non-diabetic individuals who developed T2DM after 0.1 to 10.5 years (mean, 5.4 years), and, for each diabetes case, two referents matched for sex, age, and year of health survey. Baseline variables included oral glucose tolerance test, BMI, blood pressure, blood lipids, adipokines, inflammatory markers, insulin resistance, and beta-cell function. Exploratory and confirmative factor analyses were applied to hypothesize the structure of the MetSy. The prediction of T2DM by the different factors was evaluated by multivariate logistic regression analysis.

RESULTS

A hypothetical five-factor model of intercorrelated composite factors was generated. The inflammation, dyslipidemia, and blood pressure factors were predicitive only in univariate analysis. In multivariable analyses, two factors independently and significantly predicted T2DM: an obesity/insulin resistance factor and a glycemia factor. The composite factors did not improve the prediction of T2DM compared with single variables. Among the original variables, fasting glucose, proinsulin, BMI, and blood pressure values were predictive of T2DM.

DISCUSSION

Our data support the concept of a MetSy, and we propose five separate clusters of components. The inflammation and dyslipidemia factors were not independently associated with diabetes risk. In contrast, obesity and accompanying insulin resistance and beta-cell decompensation seem to be two core perturbations promoting and predicting progression to T2DM.

Risk predictors and frequency of cardiovascular symptoms occurring during cardiac rehabilitation programs in phase III-WHO

INTRODUCTION

Rehabilitation in ambulatory heart groups has become a well established part of comprehensive cardiac treatment in Germany. Identifying patients at risk for cardiovascular symptoms is important for the efficiency and safety of the program.

METHODS

Questionnaires were mailed to ambulatory heart groups in the state of Hessen, Germany, and returned by 1935/13 174 (15%) patients, age 65.9 +/- 7.6 years, 1504/1935 (77.7%) males, comprising approximately 674 000 patient exercise hours.

RESULTS

828 symptoms were reported by 538 patients, comprising dyspnea in 330/538 (61.3%), angina pectoris in 80/538 (14.9%), palpitation in 145/538 (27%), tachycardia in 59/538 (11%), dizziness in 152/538 (28.3%), fainting in 6/538 (1.1%), and others in 47/538 (8.7%). Cardiovascular symptoms occurred more frequently in patients presenting with overexertion (43/68 (63.2%), p < 0.0001, RR 4.77 [95% CI 3.01-7.56]), chronic heart failure (115/291 (39.5%) vs 419/1624 (25.8%), p < 0.0001, RR 1.88 [95% CI 1.45-2.43]), lower exercise capacity (1.49 +/- 0.4 vs 1.59 +/- 0.5 W/kg body weight, p = 0.0002, mean difference -0.096 [95% CI (-0.146) -(-0.046)]), hypertension (269/ 854 (31.5%) vs 266/1068 (24.9%), p = 0.001, RR 1.39 [95% CI 1.14-1.69]), and hyperlipidemia (280/ 907 (30.9%) vs 255/1015 (25.1%), p = 0.005, RR 1.33 [95% CI 1.09-1.63]). Cardiovascular symptoms were more frequent in women (141/431(32.7%) vs 397/1503 (26.4%), p = 0.01, RR 1.35 [95% CI 1.08-1.71]). Overexertion (p < 0.0001), heart failure (p = 0.003), and hypertension (p = 0.05) are significant independent predictors of cardiovascular symptoms, while female gender (p = 0.06), and hyperlipidemia (p = 0.07) are not as significant. Previous myocardial infarction and diabetes had no statistical significant impact on cardiovascular symptoms.

CONCLUSION

Patients likely to experience cardiovascular symptoms in ambulatory rehabilitation can be identified by their medical history and perceived exertion.

Serum interleukin-6 correlates with endothelial dysfunction in healthy men independently of insulin sensitivity

OBJECTIVE

Interleukin (IL)-6 is a proinflammatory cytokine that is implicated in the pathogenesis of atherosclerosis and insulin resistance. Both endothelial dysfunction and insulin resistance are among the earliest abnormalities that can be detected in people at risk for cardiovascular events. We aimed to evaluate whether increased serum IL-6 concentrations associated with endothelial dysfunction are independent of insulin sensitivity in apparently healthy men.

RESEARCH DESIGN AND METHODS

Association studies were performed in well-characterized nondiabetic Caucasian men (n = 99) recruited for energy balance studies. Insulin sensitivity (minimal model) and brachial vascular reactivity (high-resolution external ultrasound) were assessed. Circulating IL-6 concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

Serum IL-6 was an independent contributor to the variance of endothelium-dependent vasodilatation after adjusting for age, BMI, smoking status, LDL cholesterol, systolic blood pressure, diastolic blood pressure, and insulin sensitivity (P = 0.001). In fact, circulating IL-6 was negatively associated with endothelium-dependent vasodilatation (r = -0.247, P = 0.014) and insulin sensitivity (r = -0.262, P = 0.011) and correlated positively with age (r = 0.241, P = 0.016), BMI (r = 0.240, P = 0.017), systolic blood pressure (r = 0.299, P = 0.003), diastolic blood pressure (r = 0.295, P = 0.003), and triglycerides (r = 0.212, P = 0.035). No significant associations were observed between endothelium-independent vasodilatation and serum IL-6 concentrations.

CONCLUSIONS

Circulating IL-6 is linked to endothelial dysfunction independently of insulin sensitivity in apparently healthy men.

Overweight induced by high-fat diet delays rat cutaneous wound healing

Prolonged wound healing is a complication that contributes to morbidity and mortality. Overweight people regularly undergo surgery and trauma, and often develop chronic wounds, but the effects of the adipose tissue excess on cutaneous wound healing are not well understood. This study tested the hypothesis that overweight induced by a high-fat diet impairs rat cutaneous wound healing. Male Wistar rats were fed with either a high-fat or a standard (control) diet. After 15 weeks, an excisional lesion was done and the animals were killed 21 d later. Wound contraction and re-epithelialization, blood pressure, glucose and retroperitoneal fat were evaluated. After killing, lesion and adjacent normal skin were formol-fixed and paraffin-embedded. Inflammatory infiltrate, myofibroblasts, collagen fibres and cellular proliferation were analysed and blood vessels were evaluated using stereological methods. There was no difference in blood pressure and glucose, but retroperitoneal fat increased in the high-fat diet group. Animals fed with the high-fat diet presented delayed wound contraction and re-epithelialization. It was found that 21 d after wounding, overweight induced by a high-fat diet increased the inflammatory infiltrate and delayed myofibroblastic differentiation, collagen deposition, epithelial and connective tissue cell proliferation, and angiogenesis. These findings support the hypothesis that a high-fat diet exerts negative effects on rat cutaneous wound healing, due mainly to the prolongation of the inflammatory phase.

Dietary effects on oxidation of low-density lipoprotein and atherogenesis

Oxidization of low-density lipoprotein (LDL) particles leads to formation of atherosclerotic lesions and increased risk of cardiovascular disease (CVD) via a complex cascade of biochemical events occurring mostly within the arterial wall. Multiple dietary factors impact LDL oxidation levels, such as fat-rich meals, hyper- and hypocaloric diets, and specific nutrients (vitamins E, C, and beta-carotene; mono- and polyunsaturated fatty acids; and polyphenolic compounds). These basic nutrients are naturally present at high concentrations, individually or in combinations, in common foods (fruits/vegetables, vegetable oils, red wine, soy, fish, tea); in turn, these foods are the main components of well-defined diets (Mediterranean, East Asian, balanced vegetarian) that display protective action against LDL oxidation and potentially against CVD. For most nutrients, however, both positive and negative evidence exists as to the extent of their antioxidant properties and protection against risk of CVD, prompting caution in the interpretation of data reports and health claims of advertised antioxidant products.

Obesity and the Metabolic Syndrome: The Stress on Society

The problem of obesity was only accepted by the World Health Organization as of major public health importance in 1997 when the criteria for the specification of the metabolic syndrome were also being sought. Then the risk factor analyses of the determinants of global ill health at the start of the millennium showed that an excessive body mass index (BMI) above the optimum of 21 was one of the top 10 contributors. No analyses could be related to abdominal obesity because of the absence of systematic representative surveys of waist circumferences but the ill health attributable to excess weight included the risk factors specified in the metabolic syndrome and showed that the co-morbidities in Asia were far greater than those predicted from simply an excess weight. The recent proposed definition of the metabolic syndrome includes these different criteria specified on an ethnic basis but there is now a need to recognize that abdominal obesity is more common on the developing world and linked to childhood stunting and early deprivation. The importance of intrauterine and postnatal epigenetic and altered organ function needs to be recognized. Thus the co-morbidities associated with weight gain and the development of the metabolic syndrome dominate in the developing world where the majority of the population is proving more susceptible to the effects of weight gain than Caucasians now living in affluent societies. This therefore presents a major challenge in both research and public policy terms.

Allograft vasculopathy versus atherosclerosis

Over the last 4 decades, heart transplantation (HTx) has evolved as a mainstream therapy for heart failure. Approximately half of patients needing HTx have organ failure consequent to atherosclerosis. Despite advances in immunosuppressive drugs, long-term success of HTx is limited by the development of a particular type of coronary atherosclerosis, referred to as cardiac allograft vasculopathy (CAV). Although the exact pathogenesis of CAV remains to be established, there is strong evidence that CAV involves immunologic mechanisms operating in a milieu of nonimmunologic risk factors. The immunologic events constitute the principal initiating stimuli, resulting in endothelial injury and dysfunction, altered endothelial permeability, with consequent myointimal hyperplasia and extracellular matrix synthesis. Lipid accumulation in allograft arteries is prominent, with lipoprotein entrapment in the subendothelial tissue, through interactions with proteoglycans. The apparent endothelial "intactness" in human coronary arteries of the transplanted heart suggest that permeability and function of the endothelial barrier altered. Various insults to the vascular bed result in vascular smooth muscle cell (SMC) activation. Activated SMCs migrate from the media into the intima, proliferate, and elaborate cytokines and extracellular matrix proteins, resulting in luminal narrowing and impaired vascular function. Arteriosclerosis is a broad term that is used to encompass all diseases that lead to arterial hardening, including native atherosclerosis, postangioplasty restenosis, vein bypass graft occlusion, and CAV. These diseases exhibit many similarities; however, they are distinct from one another in numerous ways as well. The present review summarizes the current understanding of the risk factors and the pathophysiological similarities and differences between CAV and atherosclerosis.

Association of vascular risk factors with increasing glycemia even in normoglycemic subjects in an older Chinese population: the Guangzhou Biobank Cohort Study

Hyperglycemia increases cardiovascular disease risk, but the association between increasing glycemia and cardiovascular risk factors, angina, and coronary heart disease in normoglycemic subjects is less clear, particularly in Chinese. We report on possible associations in a large group of Mainland Chinese subjects. A total of 10,400 older subjects (> or = 50 years) were recruited, and vascular risk factors were measured, including anthropometry, blood pressure, and fasting plasma biochemical factors including glucose, lipid profile, and C-reactive protein (CRP). Subjects were categorized by glycemic status, and the relationship between glycemia and cardiovascular risk factors was investigated using analysis of variance and multiple linear regression analyses. Tertiles of fasting glucose levels showed a clear positive relationship with cardiovascular risk factors including age, obesity, blood pressure, lipid levels, and CRP (P < .001 for all). The overall prevalence of self-reported vascular disease was low, but significantly associated with increasing glycemia. Multiple regression showed that waist circumference (standardized regression coefficient beta = .10, P < .001), triglycerides (beta = 0.16, P < .001), CRP (beta = 0.06, P < .001), female sex (beta = .03, P = .007), high-density lipoprotein cholesterol (beta = -.02, P = .016), and mean arterial pressure (beta = .06, P < .001) were independently associated with fasting glucose levels. Among the normoglycemic subjects (n = 5190), increasing glycemia was still associated with increasing obesity indices, systolic blood pressure, triglyceride, and CRP levels (all P < .05). Increasing glycemia, even in the reference range, is associated with increasing prevalence of vascular risk factors. Control of these risk factors, particularly obesity, the most important avoidable independent determinant of glycemia in normoglycemic subjects, is critical to reduce the risk of the associated vascular disease.

Metabolic syndrome by the international diabetes federation definition in Hong Kong Chinese

In this report, we aimed to examine the impact of the new International Diabetes Federation (IDF) definition on the prevalence and clinical characteristics of subjects with metabolic syndrome (MES). Data were obtained from a prevalence survey for cardiovascular risk factors in a Hong Kong Chinese working population. There were 1513 subjects well representing all occupational groups from managers to general laborers [910 (60.1%) men and 603 (39.9%) women (mean age 37.5+/-9.2, median 37.0, range 18-66 years)]. The crude prevalence of MES defined by the IDF criterion was 7.4% (compared to other criteria: NCEP, 9.6%; WHO, 13.4% and EGIR, 8.9%). The age-standardized prevalence of MES by the IDF criterion was 8.8% in women and 7.3% in men. Subjects with MES defined by IDF criterion had higher body mass index and waist compared to those with MES defined by NCEP or WHO criteria, and lower triglyceride compared to those with MES defined by NCEP criterion after adjustment for age, gender and smoking. Non-MES subjects defined by IDF criterion had higher 2h glucose and insulin resistance compared to non-MES subjects defined by WHO. In conclusion, the new IDF criterion for MES is easy to implement in clinical practice. It may be potentially more 'specific' in identifying subjects with MES although compared to the NCEP criterion, it may have missed a proportion of subjects, especially men, who have metabolic derangement. Prospective and interventional studies are needed to validate the prognostic values of this new definition in comparison with other existing definitions.

Plasma fatty acid composition is associated with the metabolic syndrome and low-grade inflammation in overweight adolescents

BACKGROUND

Together with adiposity, plasma fatty acid (FA) composition can modulate the development of the metabolic syndrome (MS).

OBJECTIVE

Our aim was to investigate the relations of FA composition in plasma phospholipids and cholesterol esters (CEs) with weight status, MS, and inflammation in adolescents.

DESIGN

Plasma FA composition was measured by gas-liquid chromatography in 120 (60 normal-weight and 60 overweight) 12-y-old adolescents. We also measured the presence of MS, insulin resistance with the homeostasis model assessment, and interleukin 6 and C-reactive protein concentrations in the adolescents.

RESULTS

MS was present in 25% of the overweight adolescents but in none of the normal-weight adolescents. Compared with overweight adolescents, normal-weight adolescents had lower saturated FAs (SFAs) in both phospholipids (P < 0.001) and CEs (P < 0.01) and higher docosahexaenoic acid in phospholipids (P < 0.001). In overweight subjects, FA composition was associated with MS features independent of body fat. The odds ratios of MS for a 0.1 increase in the ratio of polyunsaturated FAs (PUFA) to SFAs (PUFA:SFA) were 0.91 in phospholipids (P = 0.03) and 0.90 in CEs (P = 0.06). In phospholipids, PUFA:SFA and linoleic acid were associated positively with HDL cholesterol (P < 0.01 for both). PUFA:SFA in phospholipids and CEs were associated inversely with interleukin 6 (P < 0.05 for both). Eicosapentaenoic acid in phospholipids (P = 0.06) and CEs (P < 0.05) and linolenic acid in CEs (P < 0.05) were inversely related to C-reactive protein. These relations remained significant after adjustment for the waist-to-hip ratio. No significant relation between FA composition and the homeostasis model assessment was observed.

CONCLUSIONS

Plasma FA composition is associated with weight status in healthy adolescents. High intake of long-chain PUFAs, especially n-3 PUFAs, may protect obese subjects against MS and low-grade inflammation as early as adolescence.

Obesity

Excess bodyweight is the sixth most important risk factor contributing to the overall burden of disease worldwide. 1.1 billion adults and 10% of children are now classified as overweight or obese. Average life expectancy is already diminished; the main adverse consequences are cardiovascular disease, type 2 diabetes, and several cancers. The complex pathological processes reflect environmental and genetic interactions, and individuals from disadvantaged communities seem to have greater risks than more affluent individuals partly because of fetal and postnatal imprinting. Obesity, with its array of comorbidities, necessitates careful clinical assessment to identify underlying factors and to allow coherent management. The epidemic reflects progressive secular and age-related decreases in physical activity, together with substantial dietary changes with passive over-consumption of energy despite the neurobiological processes controlling food intake. Effective long-term weight loss depends on permanent changes in dietary quality, energy intake, and activity. Neither the medical management nor the societal preventive challenges are currently being met.

Relationship of C-reactive protein with components of the metabolic syndrome in normal-weight and overweight elderly

BACKGROUND AND AIM

C-reactive protein (CRP) is known to be elevated in the metabolic syndrome. We aimed to explore in more detail the relationship between CRP and other components of the metabolic syndrome in a general population of 605 Dutch elderly individuals aged 65-84 years.

METHODS AND RESULTS

Data were collected on body mass index (BMI), plasma CRP, plasma plasminogen activator inhibitor 1 (PAI-1), serum insulin, serum lipids, blood pressure, lifestyle and medical history. CRP was log-transformed (ln-CRP) to improve normality. Associations of ln-CRP with components of the metabolic syndrome were studied by multivariate linear regression analysis, in strata of gender and overweight status, with adjustment for age, physical activity, and smoking habits. A total of 322 subjects (53%) were overweight (BMI > or =25 kg/m2).

CONCLUSIONS

In normal-weight women, ln-CRP was significantly associated with BMI, PAI-1, serum insulin, and HDL-cholesterol. In overweight women, however, these relationships were weak and not statistically significant. Findings were similar in men, although less pronounced than in women. Our data suggest that the role of CRP in the metabolic syndrome is modified by the amount of body fat.

The Cardiovascular Continuum in Asia-A New Paradigm for the Metabolic Syndrome

Atherosclerosis, myocardial infarction, and heart failure are cardiovascular complications in a continuum that begins with risk factors such as hypertension, diabetes, and dyslipidemia. These particular cardiovascular risk factors commonly occur together in obese individuals as components of the metabolic syndrome. In Asia, there is a trend toward an increase in the prevalence of the metabolic syndrome and cardiovascular disease. Abdominal adiposity is arguably the key factor underlying the development of insulin resistance and the metabolic syndrome. It is now known that adipose tissues secrete adipokines, and in obese subjects, there is a chronic low-grade inflammation. The inflammation and the associated endothelial dysfunction are reversible in the early stages. The Asian diet is low in animal fat but high in carbohydrates. Recent studies suggest that low-carbohydrate diets are more effective than low fat diets in inducing weight loss, suggesting that excessive carbohydrate rather than fat is the cause of obesity. Strategies to combat cardiovascular disease should now focus on tackling the epidemic of obesity and developing innovative and effective lifestyle and pharmacological interventions.

Influence of Body Condition Score on Relationships Between Metabolic Status and Oxidative Stress in Periparturient Dairy Cows

Twenty-four dairy cows were monitored during the transition period. We observed changes of oxidative status and relationships between oxidative and metabolic status. Body condition score (BCS) of the 24 animals at the beginning of the trial (30.4 +/- 2 d before expected calving) was between 2.0 and 3.6. The BCS was recorded and blood samples were collected weekly during the last 30 d of pregnancy and the first 30 DIM. Plasma samples were analyzed to determine indices of oxidative status: reactive oxygen metabolites (ROM); thiobarbituric acid-reactive substances (TBARS); thiol groups (SH); glutathione peroxidase (GSH-Px), and indices of energy metabolism: glucose, beta-hydroxybutyrate, and nonesterified fatty acids. In erythrocytes we determined indices of oxidative status: GSH-Px, superoxide dismutase (SOD), and intracellular SH. Before calving, cows showed an increase of plasma SH, SOD, and GSH-Px, a decrease of erythrocyte GSH-Px and plasma ROM, and no changes in erythrocyte SH. After calving, cows showed a decrease of plasma and erythrocyte SH and SOD, and an increase of ROM, TBARS, and plasma GSH-Px. Cows with higher BCS at the beginning of the trial and greater loss of BCS after calving, had higher plasma ROM, TBARS, and SH, and lower SOD and erythrocyte SH in the postpartum period. Oxidative status of dairy cows was related to energy status. Cows with higher BHBA and NEFA showed higher ROM and TBARS and lower levels of antioxidants. Results of the present study demonstrated that cows can experience oxidative stress during the peripartum period, and cows with higher BCS and greater BCS losses are more sensitive to oxidative stress.

Tumour necrosis factor-alpha gene haplotype is associated with pre-eclampsia

We determined whether polymorphisms in the promoter region of the tumour necrosis factor alpha (TNF-alpha) gene contributes to differences in susceptibility to develop pre-eclampsia. The study involved 133 pre-eclamptic and 115 healthy pregnant women who were genotyped for the G-308A polymorphism of the TNF-alpha gene. The frequency of the G-308A allele was more common in the pre-eclampsia group than among the controls (P=0.046), giving an odds ratio of 0.57 (95% CI: 0.32-0.99), but there were no differences in the genotype distribution. The data from the G-308A polymorphism was combined with the previously published genotype and allele data from the C-850T polymorphism of the TNF-alpha gene, and used to assess a haplotype estimation analysis. Estimated overall pair of loci haplotype frequencies differed significantly between the groups (P=0.023+/-0.004). In the single haplotype association analysis, the haplotype C-A versus others was over-represented in the pre-eclampsia group (P=0.041+/-0.003), whereas the haplotype T-G versus others was less common in the pre-eclampsia group (P=0.035+/-0.003), compared with the controls. In conclusion, the polymorphisms of the TNF-alpha gene showed a significant haplotype association with susceptibility to pre-eclampsia in the Finnish population.

Abdominal adipose tissue cytokine gene expression: relationship to obesity and metabolic risk factors

Adipose tissue is a major source of inflammatory and thrombotic cytokines. This study investigated the relationship of abdominal subcutaneous adipose tissue cytokine gene expression to body composition, fat distribution, and metabolic risk during obesity. We determined body composition, abdominal fat distribution, plasma lipids, and abdominal subcutaneous fat gene expression of leptin, TNF-alpha, IL-6, PAI-1, and adiponectin in 20 obese, middle-aged women (BMI, 32.7 +/- 0.8 kg/m2; age, 57 +/- 1 yr). A subset of these women without diabetes (n = 15) also underwent an OGTT. In all women, visceral fat volume was negatively related to leptin (r = -0.46, P < 0.05) and tended to be negatively related to adiponectin (r = -0.38, P = 0.09) gene expression. Among the nondiabetic women, fasting insulin (r = 0.69, P < 0.01), 2-h insulin (r = 0.56, P < 0.05), and HOMA index (r = 0.59, P < 0.05) correlated positively with TNF-alpha gene expression; fasting insulin (r = 0.54, P < 0.05) was positively related to, and 2-h insulin (r = 0.49, P = 0.06) tended to be positively related to, IL-6 gene expression; and glucose area (r = -0.56, P < 0.05) was negatively related to, and insulin area (r = -0.49, P = 0.06) tended to be negatively related to, adiponectin gene expression. Also, adiponectin gene expression was significantly lower in women with vs. without the metabolic syndrome (adiponectin-beta-actin ratio, 2.26 +/- 0.46 vs. 3.31 +/- 0.33, P < 0.05). We conclude that abdominal subcutaneous adipose tissue expression of inflammatory cytokines is a potential mechanism linking obesity with its metabolic comorbidities.

Unaltered TNF-alpha production by macrophages and monocytes in diet-induced obesity in the rat

Background

Recent findings have established an association between obesity and immune dysfunction. However, most of the studies investigating the effects of obesity on immune function have been carried out in genetically obese rodent models. Since human obesity is mostly due to intake of a high fat diet and decreased energy expenditure, we asked whether immunological defects also occur in diet-induced obesity. Specifically, we focused on the function of monocytes and macrophages, as these cells are thought to be involved in the low-grade inflammation present in obesity.

Methods

Male Sprague-Dawley rats were fed a high-fat or a standard chow diet for either 2 or 10 weeks. At the end of the intervention period animals were anaesthetised, blood collected for determination of plasma mediator concentrations and lipopolysaccharide (LPS) stimulated production of TNF-α by monocytes. LPS stimulated production of TNF-α in alveolar macrophages was also determined.

Results

High-fat feeding for either 2 or 10 weeks resulted in significant increases in fat mass and serum leptin. Although increased serum leptin has previously been linked to modulation of innate immunity, we found no significant difference in the LPS stimulated production of TNF-α by either blood monocytes or alveolar macrophages between the dietary groups. Furthermore, we failed to find a significant increase in circulating TNF-α concentrations in obese animals, as reported for genetically obese animals.

Conclusion

Our data suggest that defects in innate immune function observed in genetically obese animals are not mimicked by dietary obesity, and may more likely reflect the gross abnormality in leptin function of these models. Further work is required delineate the effects of dietary obesity on inflammatory state and immune function.

The impact of laparoscopy on bariatric surgery

The rising popularity of bariatric surgery over the past several years is attributable in part to the development of laparoscopic bariatric surgery. Morbidly obese patients have associated comorbid conditions that may predispose them to postoperative morbidity. The laparoscopic approach to bariatric surgery offers a minimally invasive option that reduces the physiologic stress and provides clinical benefits, as compared with the open approach. This review summarizes the impact of laparoscopic surgery on bariatric surgery, the various risk factors that could potentially predispose morbidly obese patients to postoperative morbidity, the fundamental differences between laparoscopic and open bariatric surgery, and the physiology of reduced tissue injury associated with laparoscopic bariatric surgery.

Circulating osteoprotegerin levels are associated with age, waist-to-hip ratio, serum total cholesterol, and low-density lipoprotein cholesterol levels in healthy Korean women

Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of nuclear factor I masculine B ligand. Osteoprotegerin has been shown to be an important inhibitor of osteoclastogenesis and arterial calcification in animal models. Recently, OPG has been proposed as a link molecule between osteoporosis and arterial calcification, but the relationship between circulating OPG levels and cardiovascular disease in human populations is unclear. Thus, the aim of this study was to investigate the relationship between circulating OPG levels and cardiovascular risk factors in healthy Korean women. The subjects were 286 women aged 37 to 73 (mean +/- SD, 51.5 +/- 6.9 years). We examined blood pressure, body mass index, and waist-to-hip ratio. Serum concentrations of OPG were determined by enzyme-linked immunosorbent assay. Fasting plasma glucose levels, serum lipid profiles, insulin levels, and serum follicle-stimulating hormone (FSH) levels were determined by standard methods and homeostasis model assessment of insulin resistance was calculated. We observed a significant association between serum OPG levels and age, waist-to-hip ratio, total cholesterol, low-density lipoprotein cholesterol, and FSH levels (P < .05). Among the metabolic components, the older, obese, and hypercholsterolemic subjects had higher serum OPG levels (P < .05). However, no significant relationship was found between serum OPG levels and blood pressure and fasting plasma glucose levels. We found that mean serum OPG levels were about 11% greater in postmenopausal women (mean +/- SD, 1358.5 +/- 380.0 pg/mL) than in premenopausal women (mean +/- SD, 1228.8 +/- 407.7 pg/mL, P < .001). In multiple regression analysis with OPG as the dependent variable, serum FSH and low-density lipoprotein cholesterol levels were the significant predictor for serum OPG level (R(2) = 0.051, P < .05). In conclusion, our results show that circulating OPG levels are partly associated with cardiovascular risk factors and menopausal status in healthy Korean women. Out findings suggest that OPG may be an important paracrine factor of cardiovascular disease in the female population.

The metabolic syndrome in obese postmenopausal women: relationship to body composition, visceral fat, and inflammation

The purpose of this study was to investigate whether aerobic fitness, body composition, body fat distribution, and inflammation are different in obese postmenopausal women with and without the metabolic syndrome (MS), and whether the severity of MS is associated with these characteristics. Fifty-eight women (age, 59 +/- 1 yr; body mass index, 33.0 +/- 0.6 kg/m2)completed testing of maximal aerobic capacity, body composition (fat mass, lean mass, and percent body fat), body fat distribution (sc and visceral fat areas, and regional adipocyte sizes), and inflammation (C-reactive protein, IL-6, and TNF-alpha,and their soluble receptors). Lean mass (44.4 +/- 0.9 vs. 41.2 +/- 0.9 kg; P < 0.05), visceral fat area (180 +/- 10 vs. 135 +/- 7 cm2; P <0.001), and plasma soluble TNF receptor 1 (sTNFR1; 860 +/- 25 vs. 765 +/- 42 pg/ml; P < 0.05) were higher in women with the MS(n = 27) than in those without the MS (n = 31). The number of MS components was directly related to weight, body mass index, fat mass, lean mass, visceral fat area, and plasma sT-NFR1. We conclude that obese older women with the MS are characterized by high lean mass, high visceral fat, and elevated sTNFR1, and the severity of the MS is associated with body composition, visceral adiposity, and inflammation.

A novel pathway to the manifestations of metabolic syndrome

Pathways leading from obesity to the manifestations of metabolic syndrome involve a number of metabolic risk factors, as well as adipokines, mediators of inflammatory response, thrombogenic and thrombolytic parameters, and vascular endothelial reactivity. Increased adipose tissue mass contributes to augmented secretion of proinflammatory adipokines, particularly tumor necrosis factor-alpha (TNF alpha), along with diminished secretion of the "protective" adiponectin. In our view, TNF alpha and adiponectin are antagonistic in stimulating nuclear transcription factor-kappa B (NF-kappa B) activation. Through this activation, TNF alpha induces oxidative stress, which exacerbates pathological processes leading to oxidized low-density lipoprotein and dyslipidemia, glucose intolerance, insulin resistance, hypertension, endothelial dysfunction, and atherogenesis. NF-kappa B activation further stimulates the formation of additional inflammatory cytokines, along with adhesion molecules which promote endothelial dysfunction. Elevated free fatty acid, glucose, and insulin levels enhance this NF-kappa B activation and further downstream modulate specific clinical manifestations of metabolic syndrome.

Increased expression of TNF-alpha, IL-6, and IL-8 in HALS: implications for reduced adiponectin expression and plasma levels

Human immunodeficiency virus (HIV)-associated lipodystrophy syndrome (HALS) is a side effect of highly active antiretroviral therapy of HIV-infected patients; however, the mechanism of the lipodystrophy and insulin resistance seen in this syndrome remains elusive. Adiponectin, an adipocyte-specific protein, is thought to play an important role in regulating insulin sensitivity. We investigated circulating levels and gene expression of adiponectin in subcutaneous abdominal adipose tissue (AT) from 18 HIV-infected patients with HALS compared with 18 HIV-infected patients without HALS. Implications of cytokines for adiponectin levels were investigated by determining circulating levels of TNF-alpha, IL-6, and IL-8 as well as gene expression of these cytokines in AT. HALS patients exhibited 40% reduced plasma adiponectin levels (P < 0.05) compared with non-HALS subjects. Correspondingly, adiponectin mRNA levels in AT were reduced by >50% (P = 0.06). HALS patients were insulin resistant, and a positive correlation was found between plasma adiponectin and insulin sensitivity (r = 0.55, P < 0.01) and percent limb fat (r = 0.61, P < 0.01). AT mRNA of TNF-alpha, IL-6, and IL-8 was increased in AT of HALS subjects (P < 0.05), and both AT TNF-alpha mRNA and plasma TNF-alpha were negatively correlated to plasma adiponectin (P < 0.05). Finally, TNF-alpha was found in vitro to inhibit human AT adiponectin mRNA by 80% (P < 0.05). In conclusion, HALS patients have reduced levels of plasma adiponectin and adiponectin mRNA in AT. Increased cytokine mRNA in AT is hypothesized to exert an inhibitory effect on adiponectin gene expression and, consequently, to play a role in the reduced plasma adiponectin levels found in HALS patients.

Obesity and Heart Failure

Current statistics on global obesity are staggering. In 2002, the International Obesity Task Force estimated that worldwide, nearly 1 billion (6%) people were overweight or obese. The American Heart Association's 2002: "Top 10" Research Advances for the Treatment of Heart Disease include obesity as a strong and independent risk factor for developing heart failure. This article outlines national and world statistics, cardiac risk factors, and pathophysiologic theories outlining the cellular mechanisms that associate obesity and heart failure. Access to guidelines for effective screening, evaluation, and treatment of obesity are also provided.

Cardiac allograft vasculopathy: central role of endothelial injury leading to transplant "atheroma"

Endothelial injury plays a central role in the pathophysiologic mechanisms underlying cardiac allograft vasculopathy (CAV). Although the accelerated course of CAV and its localization to the allograft support an important role for the alloimmune response, there is considerable evidence implicating lipoprotein abnormalities, metabolic disturbances, viral infections, and systemic inflammation in the process. This multifactorial basis for CAV may be put into a pathophysiologic context in which endothelial cell injury is the triggering event that initiates and drives the proliferative and fibrotic processes characteristic of CAV. In the transplant setting, endothelial cell injury is induced by multiple factors, including brain death, ischemia-reperfusion, alloimmune responses, and viral infections. Once initiated, propagation of the proliferative processes that ultimately lead to vascular occlusion is enhanced by the abnormal metabolic environment of elevated lipoproteins and insulin resistance encountered in most patients. This review examines the evidence for the role of potential triggers of endothelial injury in the pathophysiology of CAV and discusses the central role of the nitric oxide pathway in the disease process.

Genotype, obesity and cardiovascular disease--has technical and social advancement outstripped evolution?

Teleologically, our ancestors were highly adapted hunter-gatherers. In recent history, the environment in which Homo sapiens exists has altered drastically and humans are exposed to environments for which the hunter-gatherer genotype is ill-suited. The adoption of a sedentary Western lifestyle, and the case of obtaining food of a high calorific content imposed upon a thrifty genotype, have resulted in the current global epidemic of obesity, Type 2 diabetes and the Metabolic Syndrome. The ramification of this epidemic is that cardiovascular disease is becoming a global healthcare problem, which will have its greatest impact on the developing nations. A global strategy is required to reduce the impact of the Western lifestyle on the health of developing nations and prevent obesity and Type 2 diabetes. Such an approach needs to be culturally sensitive, integrated, and multidisciplinary and involve a range of interventions that work at the individual and community levels. If lifestyle measures fail, then pharmacological intervention may be necessary. For this, novel agents such as dual PPARalpha/gamma agonists may be the therapy of the future.

Insulin resistance and chronic cardiovascular inflammatory syndrome

Insulin resistance is increasingly recognized as a chronic, low-level, inflammatory state. Hyperinsulinemia and insulin action were initially proposed as the common preceding factors of hypertension, low high-density lipoprotein cholesterol, hypertriglyceridemia, abdominal obesity, and altered glucose tolerance, linking all these abnormalities to the development of coronary heart disease. The similarities of insulin resistance with another inflammatory state, atherosclerosis, have been described only in the last few decades. Atherosclerosis and insulin resistance share similar pathophysiological mechanisms, mainly due to the actions of the two major proinflammatory cytokines, TNF-alpha and IL-6. Genetic predisposition to increased transcription rates of these cytokines is associated with metabolic derangement and simultaneously with coronary heart disease. Dysregulation of the inflammatory axis predicts the development of insulin resistance and type 2 diabetes mellitus. The knowledge of how interactions between metabolic and inflammatory pathways occur will be useful in future therapeutic strategies. The effective administration of antiinflammatory agents in the treatment of insulin resistance and atherosclerosis is only the beginning of a promising approach in the management of these syndromes.

Insulin resistance and the sympathetic nervous system

The obesity epidemic is driving metabolic (insulin resistance) syndrome-related health problems including an approximately threefold increased coronary heart disease risk. Sympathetic hyperfunction may participate in the pathogenesis and complications of the metabolic syndrome including higher blood pressure, a more active renin-angiotensin system, insulin resistance, faster heart rates, and excess cardiovascular disease including sudden death. Possible factors augmenting sympathetic activation in the metabolic syndrome include alterations of insulin, leptin, nonesterified fatty acids (NEFAs), cytokines, tri-iodothyronine, eicosanoids, sleep apnea, nitric oxide, endorphins, and neuropeptide Y. Of note, high plasma NEFAs are a risk factor for hypertension and sudden death. In short-term human studies, NEFAs can raise blood pressure, heart rate, and a(1)-adrenoceptor vasoreactivity, while reducing baroreflex sensitivity, endothelium-dependent vasodilatation, and vascular compliance. Efforts to further identify the mechanisms and consequences of sympathetic dysfunction in the metabolic syndrome may provide insights for therapeutic advances to ameliorate the excess cardiovascular risk and adverse outcomes.

Insulin resistance as putative cause of chronic renal transplant dysfunction

Transplantation is the preferred organ replacement therapy for most patients with end-stage renal disease. Despite impressive improvements over recent years in the treatment of acute rejection, approximately half of all grafts will loose function within 10 years after transplantation. Chronic renal transplant dysfunction, also known as transplant atherosclerosis, is a leading cause of late allograft loss. To date, no specific treatment for chronic renal transplant dysfunction is available. Although its precise pathophysiology remains unknown, it is believed that it involves a multifactorial process of alloantigen-dependent and alloantigen-independent risk factors. Obesity, posttransplant diabetes mellitus, dyslipidemia, hypertension, and proteinuria have all been identified as alloantigen-independent risk factors. Notably, these recipient-related risk factors are well-known risk factors for cardiovascular disease, which cluster within the insulin resistance syndrome in the general population. Insulin resistance is considered the central pathophysiologic feature of this syndrome. It is therefore tempting to speculate that it is insulin resistance that underlies the recipient-related risk factors for chronic renal transplant dysfunction. Recognition of insulin resistance as a central feature underlying many, if not all, recipient-related risk factors would not only improve our understanding of the pathophysiology of chronic renal transplant dysfunction, but also stimulate development of new treatment and prevention strategies.

SOCS-1 and SOCS-3 block insulin signaling by ubiquitin-mediated degradation of IRS1 and IRS2

Inflammation associates with peripheral insulin resistance, which dysregulates nutrient homeostasis and leads to diabetes. Inflammation induces the expression of SOCS proteins. We show that SOCS1 or SOCS3 targeted IRS1 and IRS2, two critical signaling molecules for insulin action, for ubiquitin-mediated degradation. SOCS1 or SOCS3 bound both recombinant and endogenous IRS1 and IRS2 and promoted their ubiquitination and subsequent degradation in multiple cell types. Mutations in the conserved SOCS box of SOCS1 abrogated its interaction with the elongin BC ubiquitin-ligase complex without affecting its binding to IRS1 or IRS2. The SOCS1 mutants also failed to promote the ubiquitination and degradation of either IRS1 or IRS2. Adenoviral-mediated expression of SOCS1 in mouse liver dramatically reduced hepatic IRS1 and IRS2 protein levels and caused glucose intolerance; by contrast, expression of the SOCS1 mutants had no effect. Thus, SOCS-mediated degradation of IRS proteins, presumably via the elongin BC ubiquitin-ligase, might be a general mechanism of inflammation-induced insulin resistance, providing a target for therapy.