Effects of etanercept in patients with the metabolic syndrome

Insulin resistance in hyperthyroidism: the role of IL6 and TNF alpha

OBJECTIVE

Although insulin resistance is a common finding in hyperthyroidism, the implicated mechanisms are obscure. The aim of this study was to investigate whether interleukin 6 (IL6) and tumour necrosis factor alpha (TNFalpha) are related to the development of insulin resistance in hyperthyroidism of nonautoimmune origin.

DESIGN AND METHODS

A meal was given to ten hyperthyroid (HR) and ten euthyroid (EU) women. Plasma samples were taken for 360 min from the radial artery for measurements of glucose, insulin, and nonesterified fatty acids (NEFA). IL6 and TNFalpha were measured preprandially from the superficial epigastric vein and from the radial artery.

RESULTS

i) In HR versus EU: (a) arterial glucose was similar (AUC(0-360) 2087+/-57 vs 2010+/-43 mM x min), but insulin was increased (AUC(0-360) 17 267+/-2447 vs 10 331+/-666 microU/ml x min, P=0.01), (b) homeostasis model assessment (HOMA) was increased (2.3+/-0.4 vs 1+/-0.1 kg/m(2), P=0.007), (c) arterial NEFA were increased (AUC(0-360) 136+/-18 vs 89+/-7 mmol/lxmin, P=0.03), (d) arterial IL6 (2+/-0.3 vs 0.9+/-0.1 pg/ml, P=0.0009) and TNFalpha (4.2+/-0.8 vs 1.5+/-0.2 pg/ml, P=0.003) were increased, and (e) IL6 production from the subcutaneous adipose tissue (AT) was increased (18+/-6 vs 5+/-1 pg/min per 100 ml tissue, P=0.04). ii) (a) Subcutaneous venous IL6 was positively associated with HOMA (beta-coefficient=1.7+/-0.7, P=0.049) and (b) although TNFalpha was not produced by the subcutaneous AT, arterial TNFalpha was positively associated with NEFA (AUC(0-360); beta-coefficient=0.045+/-0.01, P=0.005).

CONCLUSIONS

In hyperthyroidism: i) glucose and lipid metabolism are resistant to insulin, ii) subcutaneous AT releases IL6, which could then act as an endocrine mediator of insulin resistance, iii) although there is no net secretion of TNFalpha by the subcutaneous AT, increased systemic TNFalpha levels may be related to the development of insulin resistance in lipolysis.

Obesity and upper airway control during sleep

Mechanisms linking obesity with upper airway dysfunction in obstructive sleep apnea are reviewed. Obstructive sleep apnea is due to alterations in upper airway anatomy and neuromuscular control. Upper airway structural alterations in obesity are related to adipose deposition around the pharynx, which can increase its collapsibility or critical pressure (P(crit)). In addition, obesity and, particularly, central adiposity lead to reductions in resting lung volume, resulting in loss of caudal traction on upper airway structures and parallel increases in pharyngeal collapsibility. Metabolic and humoral factors that promote central adiposity may contribute to these alterations in upper airway mechanical function and increase sleep apnea susceptibility. In contrast, neural responses to upper airway obstruction can mitigate these mechanical loads and restore pharyngeal patency during sleep. Current evidence suggests that these responses can improve with weight loss. Improvements in these neural responses with weight loss may be related to a decline in systemic and local pharyngeal concentrations of specific inflammatory mediators with somnogenic effects.

Effects of infliximab therapy on abdominal fat and metabolic profile in patients with Crohn's disease

BACKGROUND

Tumor necrosis factor is an adipocytokine possessing a well-established lipolytic effect. In Crohn's disease (CD) patients, infliximab therapy may thus result in visceral fat accumulation, which is associated with an increased risk of metabolic syndrome.

METHODS

A total of 132 CD patients were investigated. In a first prospective study, magnetic resonance imaging (MRI) quantification of subcutaneous and visceral abdominal fat was performed before and 8 weeks after initiation of infliximab induction therapy (5 mg/kg at weeks 0, 2, and 6) in 21 responding patients treated for perianal disease. In a second prospective study, fasting glycemia, glycated hemoglobin (HbA1c), HDL, LDL, and total cholesterol and triglyceride levels were assessed in 111 responding patients receiving infliximab infusions every 8 weeks, with a mean follow-up of 41 weeks.

RESULTS

A significant homogeneous 18% increase in total abdominal fat was observed in the 21 CD patients after infliximab induction therapy (P = 0.027), independently of body mass index evolution. Infliximab maintenance therapy was associated with a decrease in glycemia (P < 0.0001) and HbA1c (P = 0.0005) concentrations, together with an increase in both total cholesterol (P = 0.02) and HDL cholesterol (P = 0.008) concentrations. All glycemic and lipid parameters remained within the normal range throughout the study.

CONCLUSIONS

Infliximab induction therapy is associated with a significant increase in abdominal fat tissue in CD patients. Infliximab maintenance therapy has no deleterious effects on lipid profile and is accompanied by a decrease in glycemia and HbA1c concentrations, probably by reversing the impairment of tumor necrosis factor-induced insulin-mediated glucose uptake.

Reduced adiposity and high-fat diet-induced adipose inflammation in mice deficient for phosphodiesterase 4B

The concept that obesity is an inflammatory state has changed our understanding of this condition and suggested that pharmacological interventions targeting inflammation may be useful strategies to improve metabolic complications of obesity. Phosphodiesterase 4 (PDE4) inhibitors exhibit profound antiinflammatory effects, but whether PDE4 inhibition suppresses obesity-induced inflammation is unknown. Among PDE4 isoforms, PDE4B is the major species mediating inflammatory responses. We therefore examined obesity-related phenotypes in mice deficient for PDE4B. Compared with wild-type littermates, PDE4B-null mice were leaner, with lower fat pad weights, smaller adipocytes, and decreased serum leptin levels on both chow and high-fat diets (HFDs). PDE4B deficiency suppressed TNF-alpha mRNA levels and macrophage infiltration in white adipose tissue in mice on HFD, but insulin sensitivity was unaltered. PDE4B-null mice on HFDs had increased locomotor activity. These results suggest a previously unappreciated role for PDE4B in the regulation of energy balance and that PDE4B inhibitors could have utility in treatment of obesity and for suppression of obesity-induced inflammation in white adipose tissue.

Effects of a 6-month infliximab treatment on plasma levels of leptin and adiponectin in patients with rheumatoid arthritis

Patients with rheumatoid arthritis (RA) appear to have increased plasma levels of leptin and adiponectin. These adipokines may be implicated in the pathophysiology of RA. Tumour necrosis factor alpha (TNF-alpha) is a potential modulator of adipokines. The effects of long-term anti-TNF treatment on plasma levels of leptin and adiponectin are not clear. The aim of this study was to assess the effects of 6-month anti-TNF treatment (infliximab) on leptin and adiponectin plasma levels in RA patients. Thirty women with RA were included in the study. Patients with diabetes mellitus, any endocrine disorder or receiving any hypolipidemic or antidiabetic medication were not included. Thirty healthy age- and body mass index-matched women served as controls. Plasma levels of leptin and adiponectin were measured with enzyme immunoassay methods prior to and after the 6-month treatment with infliximab. Mean age and disease duration of patients were 51.8 +/- 14.4 and 12.2 +/- 6.7 years, respectively. Body weight did not change significantly over the 6-month period. Plasma levels of leptin and adiponectin were higher in patients than controls and did not change significantly after 6-month treatment. Interestingly, in the tertile of patients with the highest baseline adiponectin concentrations, adiponectin levels were significantly reduced (P < 0.05). Infliximab treatment did not change plasma levels of leptin and adiponectin after 6-month treatment in the whole study population. However, a reduction of adiponectin levels was observed in patients with higher baseline adiponectin levels.

Chronic etanercept treatment prevents the development of hypertension in fructose-fed rats

The purpose of this study was to investigate the effect of chronic treatment with etanercept (a soluble recombinant fusion protein consisting of the extracellular ligand-binding domain of tumor necrosis factor receptor type 2) on the development of hypertension in fructose-fed rats (FFR). High fructose feeding and treatment with etanercept (0.3 mg/kg, three times per week) was initiated simultaneously in male Wistar rats. Systolic blood pressure, fasted plasma parameters, insulin sensitivity, vascular reactivity, plasma angiotensin II (Ang II), and norepinephrine were determined following 9 weeks of treatment. FFR exhibited insulin resistance, hyperinsulinemia, hypertriglyceridemia, endothelial dysfunction, and hypertension. Treatment with etanercept prevented the rise in blood pressure without affecting insulin levels, insulin sensitivity, triglycerides, or Ang II levels in FFR. Etanercept treatment improved acetylcholine-induced relaxation and normalized endothelial nitric oxide synthase expression in aortas from FFR. The results of this study suggest that treatment with etanercept prevented the development of hypertension by improving vascular function and restoring endothelial nitric oxide synthase expression in FFR.

Decreased respiratory quotient in relation to resting energy expenditure in HIV-infected and noninfected subjects

The purpose of this study was to evaluate the relationship of respiratory quotient (RQ), a surrogate marker of substrate oxidation, as well as body composition and dietary intake to resting energy expenditure (REE) among HIV-infected patients in the current era of highly active antiretroviral therapy and among non-HIV-infected control subjects. Resting energy expenditure is increased in HIV-infected patients; but little is known regarding the potential contribution of altered substrate metabolism, body composition, and dietary intake to increased energy expenditure in this population. Respiratory quotient, REE, body composition, and dietary intake parameters were assessed in 283 HIV-infected patients and 146 community-derived HIV-negative controls who were evaluated for metabolic studies between 1998 and 2005. Respiratory quotient was lower (0.83 +/- 0.00 vs 0.85 +/- 0.01, P = .005), whereas REE adjusted for fat-free mass (FFM) was higher (31.8 +/- 0.3 vs 29.8 +/- 0.3 kcal/[d kg], P < or = .0001), in HIV-infected compared with control subjects. In multivariate modeling among HIV-infected patients, including age, sex, and parameters of immune function, FFM (beta = 24.811334, P < .0001), visceral adiposity (beta = .7182746, P = .008), and total body fat (beta = 8.0506839, P = .041) were positively associated with REE, whereas RQ was negatively associated with REE (beta = -528.4808, P = .024). Overall r(2) was equal to 0.705 and P was less than .0001 for the model. In control subjects, by contrast, only visceral adiposity (beta = 1.0612073, P = .004), total body fat (beta = 15.805547, P = .010), and FFM (beta = 22.613005, P < .0001) were significant predictors of REE; and there was no relationship with RQ. Overall r(2) was equal to 0.825 and P was less than .0001 for the model. These data suggest that alterations in substrate metabolism may contribute to increased REE in HIV-infected patients compared with control subjects.

Effects of tumor necrosis factor-alpha blockade on metabolic syndrome components in psoriasis and psoriatic arthritis and additional lessons learned from rheumatoid arthritis

Psoriasis (PsO) and psoriatic arthritis (PsA) are chronic T cell-mediated inflammatory diseases that manifest not only in the skin and joints but also in the form of cardiometabolic disturbances, which include insulin resistance, dyslipidemia, and obesity. Thus, PsO and PsA patients are predisposed to metabolic syndrome (MetS), diabetes, and cardiovascular disease. In recent years, the introduction of targeted therapy in the form of tumor necrosis factor-alpha (TNF-alpha) antagonists, such as infliximab, etanercept, and adalimumab has been an important and effective addition to the treatment armamentarium for PsO and PsA. Although TNF-alpha antagonists have produced promising results clinically in reducing cutaneous and joint manifestations of PsO and PsA, their effects on MetS components in these patients are presently unclear. This review summarizes the current limited evidence on the effects of TNF-alpha antagonists on MetS components in PsO and PsA patients and extrapolates from related literature in rheumatoid arthritis, which is also a T cell-mediated inflammatory disease, for additional information.

In vitro hyperresponsiveness to tumor necrosis factor-alpha contributes to adipokine dysregulation in omental adipocytes of obese subjects

CONTEXT

In obesity, adipocyte hypertrophy and macrophage infiltration lead to overproduction of proinflammatory adipokines, which play a crucial role in the metabolic syndrome. The molecular mechanisms underlying this overproduction are still unsettled. The role of TNF-alpha also remains controversial in human obesity.

OBJECTIVE

We revisited the contribution of TNF-alpha to adipokine dysregulation in central obesity. We more particularly assessed the involvement of TNF-alpha vs. other stromal-vascular cell (SVC)-secreted factors and searched for potential differential responses to TNF-alpha between adipocytes of lean and obese individuals.

DESIGN AND PARTICIPANTS

Primary cultures of omental adipocytes from obese and nonobese age- and sex-matched subjects were used. For some experiments, we generated media previously conditioned by SVCs, which mimic adipocyte microenvironment.

RESULTS

Adipocytes of obese subjects mainly overexpressed adipokines, in comparison with those of lean ones, when cultured in SVC-conditioned media. This was abrogated by immunoneutralization of TNF-alpha, indicating that among the numerous factors secreted by SVCs, TNF-alpha is a crucial contributor to adipokine dysregulation. Accordingly, adipocytes of obese subjects overproduced adipokines in response to direct exposure of TNF-alpha. This hyperresponsiveness was mediated by TNF-alpha receptor 1 and hyperactivation of the nuclear factor-kappaB (NF-kappaB) pathway. Correspondingly, NF-kappaB activity was increased in adipocytes of obese subjects and correlated with adipocyte size, adipokine expression, and in vivo insulin resistance. Eventually adipokine overexpression in adipocytes of obese subjects was prevented by NF-kappaB inhibitors.

CONCLUSIONS

In obesity, TNF-alpha that is [corrected] over other SVC-secreted factors, a crucial determinant of adipokine dysregulation acts on enlarged adipocytes, which are hyperresponsive to this triggering signal [corrected]

T cell-mediated inflammation in adipose tissue does not cause insulin resistance in hyperlipidemic mice

Obesity is associated with chronic inflammation in adipose tissue. Proinflammatory cytokines including tumor necrosis factor-alpha and interleukin-6 secreted by adipose tissue during the metabolic syndrome are proposed to cause local and general insulin resistance and promote development of type 2 diabetes. We have used a compound mutant mouse, Apoe(-/-)xCD4dnTGFbR, with dysregulation of T-cell activation, excessive production of proinflammatory cytokines, hyperlipidemia, and atherosclerosis, to dissect the role of inflammation in adipose tissue metabolism. These mice are lean, which avoids confounding effects of concomitant obesity. Expression and secretion of a set of proinflammatory factors including tumor necrosis factor-alpha, interferon-gamma, and monocyte chemoattractant protein-1 was increased in adipose tissue of Apoe(-/-)xCD4dnTGFbR mice, as was the enzyme 11beta-hydroxysteroid dehydrogenase type 1, which converts cortisone to bioactive cortisol. Interleukin-6, which has an inhibitory glucocorticoid response element in its promoter, was not upregulated. In spite of intense local inflammation, insulin sensitivity was not impaired in adipose tissue of Apoe(-/-)xCD4dnTGFbR mice unless exogenous interleukin-6 was administered. In conclusion, T-cell activation causes inflammation in adipose tissue but does not lead to insulin resistance in this tissue in the absence of interleukin-6.

Insulin resistance, inflammation, and non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), the major cause of abnormal liver function in the western world, is often associated with obesity and diabetes. In obese individuals, fat accumulation in the abdominal region affects both lipid and glucose metabolism, and a liver loaded with fat is insulin resistant. Insulin resistance (IR) is often associated with chronic low-grade inflammation, and numerous mediators released from immune cells and adipocytes contribute to development of IR. Recent results showing an important role for these mediators in NAFLD are providing us with a better understanding of this highly prevalent disease with implications for novel therapy development. This review highlights new aspects in development of liver steatosis and the relevance of various cytokines and adipocytokines in NAFLD.

The link between abdominal obesity and the metabolic syndrome

The clustering of cardiovascular risk factors associated with abdominal obesity is well established. Although currently lacking a universal definition, the metabolic syndrome describes a constellation of metabolic abnormalities, including abdominal obesity, and was originally introduced to characterize a population at high cardiovascular risk. Adipose tissue is a dynamic endocrine organ that secretes several inflammatory and immune mediators known as adipokines. Dysregulation of adipokine secretion, free fatty acid toxicity, and the site-specific differences in abdominal (visceral) versus subcutaneous fat support abdominal obesity as a causal factor mediating the insulin resistance, increased risk of diabetes, and cardiovascular disease in the metabolic syndrome.

Adipokines and insulin resistance

Obesity is associated with an array of health problems in adult and pediatric populations. Understanding the pathogenesis of obesity and its metabolic sequelae has advanced rapidly over the past decades. Adipose tissue represents an active endocrine organ that, in addition to regulating fat mass and nutrient homeostasis, releases a large number of bioactive mediators (adipokines) that signal to organs of metabolic importance including brain, liver, skeletal muscle, and the immune system--thereby modulating hemostasis, blood pressure, lipid and glucose metabolism, inflammation, and atherosclerosis. In the present review, we summarize current data on the effect of the adipose tissue-derived hormones adiponectin, chemerin, leptin, omentin, resistin, retinol binding protein 4, tumor necrosis factor-alpha and interleukin-6, vaspin, and visfatin on insulin resistance.

Inflammation, insulin resistance, and diabetes--Mendelian randomization using CRP haplotypes points upstream

BACKGROUND

Raised C-reactive protein (CRP) is a risk factor for type 2 diabetes. According to the Mendelian randomization method, the association is likely to be causal if genetic variants that affect CRP level are associated with markers of diabetes development and diabetes. Our objective was to examine the nature of the association between CRP phenotype and diabetes development using CRP haplotypes as instrumental variables.

METHODS AND FINDINGS

We genotyped three tagging SNPs (CRP + 2302G > A; CRP + 1444T > C; CRP + 4899T > G) in the CRP gene and measured serum CRP in 5,274 men and women at mean ages 49 and 61 y (Whitehall II Study). Homeostasis model assessment-insulin resistance (HOMA-IR) and hemoglobin A1c (HbA1c) were measured at age 61 y. Diabetes was ascertained by glucose tolerance test and self-report. Common major haplotypes were strongly associated with serum CRP levels, but unrelated to obesity, blood pressure, and socioeconomic position, which may confound the association between CRP and diabetes risk. Serum CRP was associated with these potential confounding factors. After adjustment for age and sex, baseline serum CRP was associated with incident diabetes (hazard ratio = 1.39 [95% confidence interval 1.29-1.51], HOMA-IR, and HbA1c, but the associations were considerably attenuated on adjustment for potential confounding factors. In contrast, CRP haplotypes were not associated with HOMA-IR or HbA1c (p = 0.52-0.92). The associations of CRP with HOMA-IR and HbA1c were all null when examined using instrumental variables analysis, with genetic variants as the instrument for serum CRP. Instrumental variables estimates differed from the directly observed associations (p = 0.007-0.11). Pooled analysis of CRP haplotypes and diabetes in Whitehall II and Northwick Park Heart Study II produced null findings (p = 0.25-0.88). Analyses based on the Wellcome Trust Case Control Consortium (1,923 diabetes cases, 2,932 controls) using three SNPs in tight linkage disequilibrium with our tagging SNPs also demonstrated null associations.

CONCLUSIONS

Observed associations between serum CRP and insulin resistance, glycemia, and diabetes are likely to be noncausal. Inflammation may play a causal role via upstream effectors rather than the downstream marker CRP.

[Psoriasis, metabolic syndrome and its components]

The psoriasis is a chronic dermatosis which is characterized by strong inflammation. Recent studies showed that the chronic inflammation plays an important part in the pathogenesis of many metabolic and vascular diseases. Moreover, the diseases mediated by lymphocytes TH1 were related to the myocardial infarction. Epidemiologic investigations showed that psoriasis is associated at the increased risk of Comorbidities and mortality per comparison to the general population. Thus, the psoriatic patients have a high prevalence of metabolic pathologies such as the diabetes, hypertension, obesity and hyperlipidemy. These concomitant affections can complicate the treatment of psoriasis. It is important that the dermatologist systematically seeks these concomitant pathologies among psoriatic patients. These data also suggest that the treatments of these patients improve not only the skin lesions, but also control the inflammation associated with the psoriasis.

Psoriasis comorbidities

Psoriasis is a chronic and debilitating inflammatory disease associated with serious comorbidities. Psoriasis can have a significant impact on a patient's quality of life and is associated with loss of productivity, depression, and an increased prevalence of malignancy. Emerging comorbidities of psoriasis include cardiovascular disease and metabolic syndrome. Psoriasis patients have an increased prevalence of the core components of metabolic syndrome, including obesity, dyslipidemia, and insulin resistance. The relationship between psoriasis and comorbidities such as metabolic syndrome and cardiovascular disease is likely linked to the underlying chronic inflammatory nature of psoriasis. The molecular mechanisms involved in psoriasis-associated dysregulation of metabolic function are believed to be due, in large part, to the action of increased levels of proinflammatory factors, such as tumor necrosis factor-alpha, that are central to the pathogenesis of psoriasis. Recent studies investigating the effects of tumor necrosis factor antagonists on the treatment of cardiovascular disease and metabolic syndrome support this concept.

Inflammatory mechanisms in the regulation of insulin resistance

Insulin resistance (IR) plays a key role in the pathophysiology of obesity-related diseases such as type 2 diabetes and nonalcoholic fatty liver disease. It has been demonstrated that IR is associated with a state of chronic low-grade inflammation, and several mediators released from various cell types, including immune cells and adipocytes, have been identified as being involved in the development of IR. Among those are several pro-inflammatory cytokines such as tumor necrosis factor-alpha(TNF-alpha), interleukin (IL)-1, IL-6, and various adipocytokines. Furthermore, several transcription factors and kinases such as c-Jun N-terminal kinase (JNK) and inhibitor of kappa B kinase-beta (IKKbeta), a kinase located proximal of nuclear factor-kappaB (NF-kappaB), participate in this process. Hepatocyte-specific overexpression of NF-kappaB is associated with IR and can mimic all features of fatty liver disease. Whereas the evidence for an important role of many pro-inflammatory pathways in IR in in vitro and animal studies is overwhelming, data from interventional studies in humans to prove this concept are still minor. As a complex network of inflammatory cytokines, adipocytokines, transcription factors, receptor molecules, and acute-phase reactants are involved in the development of IR, new therapeutic approaches in IR-related diseases will be based on a better understanding of their complex interactions.

Inflammatory mechanisms in the regulation of insulin resistance

Insulin resistance (IR) plays a key role in the pathophysiology of obesity-related diseases such as type 2 diabetes and nonalcoholic fatty liver disease. It has been demonstrated that IR is associated with a state of chronic low-grade inflammation, and several mediators released from various cell types, including immune cells and adipocytes, have been identified as being involved in the development of IR. Among those are several pro-inflammatory cytokines such as tumor necrosis factor-alpha(TNF-alpha), interleukin (IL)-1, IL-6, and various adipocytokines. Furthermore, several transcription factors and kinases such as c-Jun N-terminal kinase (JNK) and inhibitor of kappa B kinase-beta (IKKbeta), a kinase located proximal of nuclear factor-kappaB (NF-kappaB), participate in this process. Hepatocyte-specific overexpression of NF-kappaB is associated with IR and can mimic all features of fatty liver disease. Whereas the evidence for an important role of many pro-inflammatory pathways in IR in in vitro and animal studies is overwhelming, data from interventional studies in humans to prove this concept are still minor. As a complex network of inflammatory cytokines, adipocytokines, transcription factors, receptor molecules, and acute-phase reactants are involved in the development of IR, new therapeutic approaches in IR-related diseases will be based on a better understanding of their complex interactions.

Effects of etanercept on C-reactive protein levels in psoriasis and psoriatic arthritis

BACKGROUND

C-reactive protein (CRP), an inflammation biomarker, indicates cardiovascular risk and is elevated in psoriasis. The effect of etanercept on CRP in psoriasis has not been previously examined.

OBJECTIVES

The primary objective was to examine the effect of etanercept on CRP levels from baseline to week 12 compared with placebo. Secondary objectives included assessment of baseline CRP and relationships between CRP and body mass index (BMI), statin drug use, and Psoriasis Area and Severity Index (PASI) scores.

METHODS

A retrospective analysis was conducted of CRP levels from patients with psoriasis who participated in a randomized, double-blind, placebo-controlled, U.S. registrational study. Data were analysed separately if patients self-reported psoriatic arthritis.

RESULTS

Baseline CRP levels were elevated in patients with psoriasis with and without psoriatic arthritis. CRP was significantly reduced in both groups after 12 weeks of etanercept treatment. Patients with psoriasis with psoriatic arthritis and patients with higher BMIs had higher median baseline CRP values and greater reduction of CRP values compared with those without psoriatic arthritis and those with lower BMIs. Etanercept lowered CRP levels in statin users and nonusers. Regression analyses revealed an association between baseline PASI score and baseline CRP independent of BMI in patients with psoriasis.

CONCLUSIONS

Patients with moderate to severe plaque psoriasis, with or without psoriatic arthritis, have increased systemic inflammation demonstrated by elevated CRP levels. In psoriasis without psoriatic arthritis, skin disease activity is associated significantly with CRP elevation, independent of BMI, age and sex. Etanercept reduced CRP levels in all but the normal weight psoriasis group without psoriatic arthritis.

Eicosanoids and renal damage in cardiometabolic syndrome

BACKGROUND

Obesity, hypertension and Type 2 diabetes are major contributing factors to the increase in the number of patients that have chronic kidney disease. The clustering of visceral obesity and cardiovascular risk factors has been designated metabolic syndrome or cardiometabolic syndrome. Cardiometabolic syndrome is associated with a complex systemic inflammatory state that has been implicated in medically important complications, including endothelial dysfunction. Inflammation, endothelial dysfunction and insulin resistance are interrelated and have reciprocal relationships that link cardiovascular and metabolic diseases. Ultimately, cardiometabolic syndrome increases the risk for cardiovascular events and end-organ damage. Although the number of patients with cardiometabolic syndrome is escalating, therapeutic approaches have not been developed that provide protection to the kidney.

OBJECTIVE

The objective of this review is to provide an overview of the contribution of eicosanoids to renal damage in cardiometabolic syndrome.

RESULTS/CONCLUSION

Eicosanoids are altered in cardiometabolic syndrome and contribute to the progression of renal injury. The antihypertensive and anti-inflammatory actions of epoxides and soluble epoxide hydrolase inhibitors make these attractive eicosanoid therapeutic targets for chronic kidney disease in patients with cardiometabolic syndrome.

Effect of etanercept on insulin sensitivity in nine patients with psoriasis

Metabolic syndrome is associated to chronic low grade inflammation, characterized by increased levels of inflammatory cytokines, such as Tumor Necrosis Factor-alpha (TNF-alpha) and Interleukin-6 (IL-6). In particular, TNF-alpha causes a decrease in the insulin-stimulated kinases related to the early phases of the insulin cascade, thereby leading to insulin resistance. Etanercept is a human fusion protein used in the treatment of psoriasis and inflammatory arthritis. It blocks inflammatory response by interfering in the binding of TNF-alpha to its receptors. The aim of this case report study is to verify the effect of Etanercept on insulin sensitivity, lipid profile and inflammatory status in psoriatic patients. Nine psoriatic patients with stable, active, plaque type psoriasis were enrolled and treated with Etanercept for 24 weeks. We found an improvement in the metabolic assessment with a significant reduction of insulin plasma levels. In particular, this treatment allows to maintain their euglycemic state with lower insulin plasma levels, as confirmed by the improved Homeostasis Model Assessment (HOMA) index. We conclude that Etanercept, probably acting on inflammation, improves insulin sensitivity in psoriatic subjects.

Role of adiponectin and PBEF/visfatin as regulators of inflammation: involvement in obesity-associated diseases

Obesity and obesity-related disorders play an important role in clinical medicine. Adipose tissue, with its soluble mediators called adipocytokines, has emerged as a major endocrine organ. These adipocytokines comprise many mediators such as adiponectin, PBEF (pre-B-cell-enhancing factor)/visfatin, leptin, resistin, retinol-binding protein-4 and others. They play major roles in key aspects of metabolism, such as insulin resistance, fatty acid oxidation, inflammation and immunity. Adiponectin, a prototypic adipocytokine, is of importance in the regulation of insulin resistance, as circulating levels are decreased in obesity and diseases associated with insulin resistance. Besides its major role in regulation of insulin sensitivity, recent evidence suggests potent anti-inflammatory functions for adiponectin. These effects are paralleled by other immune-regulatory properties, such as regulation of endothelial cell function. The in vitro effects of adiponectin have been corroborated by several studies demonstrating potent in vivo anti-inflammatory effects. Many other adipocytokines, such as PBEF/visfatin, leptin, resistin or retinol binding protein-4, are involved in the physiology and pathophysiology of adipocytes, adipose tissue and related diseases. PBEF/visfatin, another recently characterized adipocytokine, has been linked to several inflammatory disease states beyond insulin resistance, such as acute lung injury or inflammatory bowel diseases. It has been recognized for many decades that obesity is accompanied by an increase in cancer and potentially some immune-mediated diseases. Understanding this new exciting world of adipocytokines will be of importance in the development of novel therapies for obesity-associated diseases.

Glycohaemoglobin as a determinant of increased fibrinogen concentrations and low-grade inflammation in apparently healthy nondiabetic individuals

OBJECTIVE

To determine the potential role of glycohaemoglobin as a possible determinant of increased fibrinogen concentrations and low-grade inflammation in a group of apparently healthy, nondiabetic individuals not expressing clinically overt atherothrombosis.

DESIGN AND MAIN OUTCOME MEASURES

We performed a cross-sectional analysis of the concentrations of glycohaemoglobin alongside the concentrations of quantitative fibrinogen and high-sensitivity C-reactive protein (hs-CRP). In all, 1511 males and 757 apparently healthy females, without diabetes mellitus or clinically evident atherothrombotic disease, were enrolled in the study during their routine annual health check-up.

RESULTS

Glycohaemoglobin entered the linear regression models as a significant determinant of quantitative fibrinogen in both genders and of hs-CRP in men. We found this to be true even following the inclusion of multiple variables known to influence the intensity of low-grade inflammation, such as age, gender, waist circumference, body mass index, blood pressure, medications, hormone therapy, glucose levels (normal or impaired fasting glucose), smoking habits, family history of coronary artery disease, lipid profile as well as alcohol consumption and sports intensity. We found glycohaemoglobin to be a significant determinant of fibrinogen concentrations in apparently healthy nondiabetic individuals not yet presenting with evident atherothrombosis.

CONCLUSIONS

This observation supports the idea that glycohaemoglobin might have an effect on fibrinogen concentrations in both genders and on hs-CRP in men. Moreover, our results suggest that glycohaemoglobin should be perceived as a continuous variable without a 'normal' cut-off point, as it may exhibit a detrimental role even when present in relatively low levels.

Relation of body composition to body mass index in HIV-infected patients with metabolic abnormalities

OBJECTIVE

To determine visceral adiposity (VAT), subcutaneous adiposity (SAT), and regional body adipose differences between HIV-infected and non-HIV-infected subjects in relation to body mass index (BMI) and World Health Organization BMI categories.

DESIGN, SETTING, AND PARTICIPANTS

Analyses were conducted of 306 HIV-infected and 107 community-derived HIV-negative subjects evaluated for metabolic studies between 1999 and 2006. Analyses were stratified by gender. Additional analyses were performed stratifying subjects by metabolic syndrome status.

RESULTS

HIV-infected men and women demonstrated decreased total extremity fat by 1.1 kg and 0.85 kg, respectively, relative to non-HIV-infected control subjects. VAT was increased among HIV-infected men and women in the normal (18.5 to 24.9 kg/m2) and overweight (25.0 to 29.9 kg/m2) categories relative to control subjects but not among those in the obese category (> or =30.0 kg/m2). In contrast, abdominal SAT was reduced among HIV-infected men in the normal and overweight categories but was similar among HIV-infected women and control subjects in these categories. Abdominal SAT was increased among HIV-infected women in the obese category relative to control subjects. Similar results were obtained limiting the analysis to HIV-infected (n = 204) and control subjects (n = 89) without the metabolic syndrome.

CONCLUSIONS

Peripheral lipoatrophy is a consistent finding among HIV-infected men and women with metabolic abnormalities. Relative increases in VAT are most pronounced among male and female HIV-infected subjects in the normal weight and overweight categories. Gender differences in abdominal SAT accumulation are observed, with preservation of SAT among HIV-infected women relative to control subjects.

Adipokines and the peripheral and neural control of energy balance

Adipokines are secreted by adipose tissue and control various physiological systems. Low leptin levels during fasting stimulate feeding, reduce energy expenditure, and modulate neuroendocrine and immune function to conserve energy stores. On the other hand, rising leptin levels in the overfed state prevent weight gain by inhibiting food intake and increasing energy expenditure. These actions are mediated by neuronal circuits in the hypothalamus and brainstem. Leptin also controls glucose and lipid metabolism by targeting enzymes such as AMP-activated protein kinase and stearoyl-coenzyme A desaturase-1 in liver and muscle. Likewise, adiponectin and resistin control energy balance and insulin sensitivity via central and peripheral targets. As highlighted in this review, there are distinct as well as common signaling pathways for adipokines. Understanding adipokine signaling in the brain and other organs will provide insights into the pathogenesis and treatment of obesity, diabetes and various metabolic disorders.

Links Between Adipose Tissue and Thrombosis in the Mouse

Obesity has become a global epidemic and carries a considerable negative impact in regard to quality of life and life expectancy. A primary problem is that obese individuals are at increased risk of suffering from cardiovascular disease complications such as myocardial infarction and stroke. Because fat accumulation is a consistent aspect of obesity, mechanisms that may link adipose tissue to cardiovascular disease complications should be considered. Proteins expressed from adipose tissue, known as adipokines, are hypothesized to have important effects on the progression and incidence of cardiovascular disease complications. This review examines the evidence that adipokines play a direct role in vascular thrombosis, an important event in cardiovascular disease complications.

Macrophage beta3 integrin suppresses hyperlipidemia-induced inflammation by modulating TNFalpha expression

OBJECTIVE

High-fat, cholesterol-containing diets contribute to hyperlipidemia. Both high-fat diets and hyperlipidemia are associated with chronic inflammatory diseases like atherosclerosis. Integrins, heterodimeric mediators of inflammatory cell recruitment, are not generally thought to be affected by diet. However, high-fat feeding promotes inflammation, atherosclerosis, and death in hyperlipidemic mice with beta3 integrin deficiency, and treatment of humans from Western populations with oral beta3 integrin inhibitors increases mortality. The mechanisms responsible for these beta3 integrin-associated events are unknown.

METHODS AND RESULTS

Here we show that diet-induced death in beta3 integrin-deficient mice is a TNFalpha-dependent process mediated by bone marrow-derived cells. In 2 different hyperlipidemic models, apoE-null and LDL receptor-null mice, beta3-replete animals transplanted with beta3-deficient marrow died with Western-type high-fat feeding whereas beta3-deficient animals transplanted with beta3-replete marrow were rescued from diet-induced death. Transplantation with beta3-deficient marrow also increased atherosclerosis. TNFalpha [corrected] expression was increased in beta3-deficient macrophages and normalized by either retroviral or adenoviral reconstitution of beta3 integrin expression. Treatment with the anti-TNFalpha antibody infliximab rescued beta3 integrin-deficient mice from Western diet-induced death, directly implicating TNFalpha in the pathophysiology triggered by diet-induced hyperlipidemia.

CONCLUSIONS

These findings suggest that macrophage beta3 integrin, acting through TNFalpha, suppresses inflammation caused by hyperlipidemia attributable to high-fat feeding.

Integrating the immune system with the regulation of growth and efficiency

Muscle growth in meat animals is a complex process governed by integrated signals emanating from multiple endocrine and immune cells. A generalized phenomenon among meat animal industries is that animals commonly fail to meet their genetic potential for growth in commercial production settings. Recent evidence indicates that adipocytes and myofibers are equipped with functional pattern recognition receptors and are capable of responding directly to the corresponding pathogens and other receptor ligands. Thus, these cells are active participants in the innate immune response and, as such, produce a number of immune and metabolic regulators, including proinflammatory cytokines and adiponectin. Specifically, the transcription factor, nuclear factor kappa B, is activated in adipocytes and muscle cells by bacterial lipopolysaccharide and certain saturated fatty acids, which are potent agonists for the Toll-like receptor-4 pattern recognition receptor. Receptor activation results in the local production of interleukin-6 and tumor necrosis factor-alpha, and creates a local environment by which these cytokines regulate both metabolic and immunological pathways. However, adipocytes are also the predominant source of the antiinflammatory hormone, adiponectin, which suppresses the activation of nuclear factor kappa B and the production of proinflammatory cytokines. The molecular ability to recognize antigens and produce regulatory molecules strategically positions adipocytes and myofibers to regulate growth locally and to reciprocally regulate metabolism in peripheral tissues.

Obesity in psoriasis: the metabolic, clinical and therapeutic implications. Report of an interdisciplinary conference and review

Experts on psoriasis convened with authorities from other medical specialties to discuss the recently described association between psoriasis, obesity and subsequent cardiovascular comorbidity. Similar to other diseases of increased systemic inflammation, psoriasis has been linked to a heightened risk of myocardial infarction, especially in the more severely affected, younger patients. However, unlike in other inflammatory diseases - such as rheumatoid arthritis - more severely affected patients with psoriasis are much more likely to be obese. Importantly, the pathophysiology of both psoriasis and obesity shows many shared cytokines that are known to contribute to features of the metabolic syndrome, such as hypertension, dyslipidaemia and insulin resistance. The strong association between psoriasis and obesity potentially makes psoriasis an important healthcare issue that requires an update in its standard of care. This meeting reviewed the evidence-based literature and addressed how, moving forward, dermatologists and other specialists may redefine the magnitude of health risk associated with more severe psoriasis and its comorbidities, while clarifying both the epidemiology and pathophysiology of the association with obesity.

Dietary fat intake and relationship to serum lipid levels in HIV-infected patients with metabolic abnormalities in the HAART era

OBJECTIVE

To evaluate dietary intake and its relationship to lipid parameters in HIV-infected patients with metabolic abnormalities.

METHOD

We prospectively determined dietary intake (4-day food records or 24-h recall) in 356 HIV-infected patients and 162 community-derived HIV-negative controls evaluated for metabolic studies between 1998-2005. Differences in dietary intake between HIV-infected patients and non-HIV-infected controls, in relation to the established 2005 USDA (United States Department of Agriculture) Recommended Dietary Guidelines, were determined. The relationship between dietary fat intake and serum lipid levels among HIV-infected individuals was also evaluated.

RESULTS

Assessment of dietary intake in this group of HIV-infected patients demonstrated increased intake of total dietary fat (P < 0.05), saturated fat (P = 0.006), and cholesterol (P = 0.006) as well as a greater percentage of calories from saturated fat (P = 0.002) and from trans fat (P = 0.02), despite similar caloric intake to the control individuals. A significantly higher percentage of HIV-infected patients were above the 2005 USDA Recommended Dietary Guidelines for saturated fat (> 10%/day) (76.0% HIV vs. 60.9% controls, P = 0.003), and cholesterol (> 300 mg/day) (49.7% HIV vs. 37.9% controls, P = 0.04). Saturated fat intake was strongly associated with triglyceride level [triglyceride level increased 8.7 mg/dl (parameter estimate) per gram of increased saturated fat intake, P = 0.005] whereas total fat was inversely associated with triglyceride level [triglyceride level decreased 3.0 mg/dl (parameter estimate) per gram of increased total fat intake, P = 0.02] among HIV-infected individuals.

CONCLUSIONS

Increased intake of saturated fat is seen and contributes to hypertriglyceridemia among HIV-infected patients who have developed metabolic abnormalities. Increased saturated fat intake should be targeted for dietary modification in this population.

Effects of TNF-alpha neutralization on adipocytokines and skeletal muscle adiposity in the metabolic syndrome

In a prior study, we have shown that tumor necrosis factor (TNF)-alpha neutralization improves inflammatory markers and total adiponectin in patients with the metabolic syndrome, without improving insulin sensitivity. In this study, we sought to extend our understanding of the effects of TNF-alpha neutralization in this human model of obesity by investigating the responses of high-molecular-weight (HMW) adiponectin, resistin, leptin, and muscle adiposity to etanercept in patients with the metabolic syndrome. Fifty-six men and women with the metabolic syndrome enrolled in a double-blind randomized placebo-controlled trial. Circulating concentrations of total and HMW adiponectin, resistin, and leptin were determined at baseline and after 4 wk of treatment with etanercept. Muscle adiposity was measured by computed tomography (CT). Although etanercept increased total adiponectin concentration, the HMW form, which is thought to mediate insulin sensitivity, was unchanged. Thus the ratio of HMW to total adiponectin decreased following etanercept treatment compared with placebo (-0.03 +/- 0.03 vs. 0.06 +/- 0.03, P = 0.02). Resistin tended to decrease in the etanercept-treated group compared with placebo (-0.6 +/- 0.7 vs. 1.2 +/- 0.7 ng/ml, P = 0.06), whereas leptin was not altered. Etanercept decreased muscle attenuation on CT [-0.61 +/- 0.64 Hounsfield units (HU) vs. 1.54 +/- 0.77 HU in placebo, P = 0.04], suggesting an increase in muscle adiposity. Together, these results demonstrate that neutralization of TNF-alpha in obese humans results in differential effects on critical adipokines and body composition indexes. These findings may help to explain the lack of effect on insulin sensitivity and extend our knowledge of the biological effects of TNF-alpha neutralization in obesity.

The adipocyte as an active participant in energy balance and metabolism

Obesity is responsible for the mounting incidence of metabolic disease in adult and pediatric populations. Understanding of the pathogenesis and maintenance of the obese state has advanced rapidly over the past 10 years. Bodily energy reserves are managed actively by complex systems that regulate food intake, substrate partitioning, and energy expenditure. An underlying assumption that circulating factors released from storage organs were able to signal bodily energy reserves was confirmed with the discovery of the leptin system. This proof of concept has spurred on the discovery of a multitude of other adipocyte-generated factors. These circulating factors signal to the brain and other organs of metabolic importance, including adipose tissue, liver, muscle, and the immune system. Adipose-derived factors have numerous implications for the basic biology of obesity and provide prospective targets for the amelioration of obesity and its adverse metabolic consequences. In this review we detail the current understanding of leptin as a prototypical adipose tissue-derived hormone related to appetite and obesity. We also describe other important adipose-derived factors in relation to their metabolic effect.

Obesity, inflammation, and insulin resistance

Weight gain and obesity are major risk factors for conditions and diseases ranging from insulin resistance and type 2 diabetes mellitus to atherosclerosis and the sequelae of nonalcoholic fatty liver disease. A chronic, subacute state of inflammation often accompanies the accumulation of excess lipid in adipose tissue and liver (hepatic steatosis), evidenced by changes in both inflammatory cells and biochemical markers of inflammation. These changes can be seen in the involved tissues and systemically, in terms of elevated circulating levels of inflammatory markers. The link between obesity and inflammation has therefore raised the important question of whether obesity-induced inflammation plays a pathogenic role in the development and progression of these disorders. We review the rapidly expanding body of animal and clinical data that support potential roles for inflammation in the pathogenesis of insulin resistance and type 2 diabetes mellitus.

The Use of Biological Agents in the Treatment of Rheumatoid Arthritis

Rheumatoid arthritis is a common and potentially devastating condition which did not have good treatment options until recently. Pharmacological treatment should not just comprise anti-inflammatory agents and corticosteroids. The current therapeutic approach is to start a disease modifying agent early in the illness to prevent eventual joint damage. Older disease modifying anti-rheumatic drugs (DMARDs) include methotrexate, sulphasalazine and hydroxychloroquine. Newer ones such as leflunomide and cyclosporine are also used. A recent advance in the management of rheumatoid arthritis is the use of biological agents which block certain key molecules involved in the pathogenesis of the illness. They include tumour necrosis factor (TNF)-blocking agents such as infliximab, etanercept and adalimumab, the anti-CD 20 agent rituximab and CTLA-4 Ig abatacept. Other agents which are in development include anti-IL6 tocilizumab, anti-CD22 and anti-lymphostat B. In this review, the efficacy and side effects of these agents, their impact on current clinical practice and future trends are discussed. Key words: Abatacept, Anti-TNF, Rituximab

Type 2 diabetes and cardiovascular disease: getting to the fat of the matterThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum

The increasing national prevalence of obesity is a major public health concern and a substantial burden on the health care resources of Canada. In addition to the direct health impact of obesity, this condition is a well-established risk factor for the development of various prevalent comorbidities including type 2 diabetes, hypertension, and cardiovascular disease. Historically, adipose tissue has been regarded primarily as an organ for energy storage. However, the discovery of leptin in the mid 1990’s revolutionized our understanding of this tissue and has focused attention on the endocrine function of adipose tissue as a source of secreted bioactive peptides. These compounds, collectively termed adipokines, regulate a number of biological functions including appetite and energy balance, insulin sensitivity, lipid metabolism, blood pressure, and inflammation. The physiological importance of adipokines has led to the hypothesis that changes in the synthesis and secretion of these compounds in the obese are a causative factor contributing to the development of obesity and obesity-related diseases in these individuals. Following from this it has been proposed that pharmacologic manipulation of adipokine levels may provide novel effective therapeutic strategies to treat and prevent obesity, type 2 diabetes, and cardiovascular disease.