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Query: UNIPROT:P05231 (interleukin-6)
 23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Non-insulin-dependent diabetes mellitus (NIDDM) is commonly associated with hypertriglyceridaemia, low serum HDL-cholesterol concentrations, hypertension, obesity and accelerated atherosclerosis (metabolic syndrome X). Since a similar dyslipidaemia occurs with the acute-phase response, we investigated whether elevated acute-phase/stress reactants (the innate immune system's response to environmental stress) and their major cytokine mediator (interleukin-6, IL-6) are associated with NIDDM and syndrome X, and may thus provide a unifying pathophysiological mechanism for these conditions. Two groups of Caucasian subjects with NIDDM were studied. Those with any 4 or 5 features of syndrome X (n = 19) were compared with a group with 0 or 1 feature of syndrome X (n = 25) but similar age, sex distribution, diabetes duration, glycaemic control and diabetes treatment. Healthy non-diabetic subjects of comparable age and sex acted as controls. Overnight urinary albumin excretion rate, a risk factor for cardiovascular disease, was also assayed in subjects to assess its relationship to the acute-phase response. Serum sialic acid was confirmed as a marker of the acute-phase response since serum concentrations were significantly related to established acute-phase proteins such as alpha-1 acid glycoprotein (r = 0.82, p < 0.0001). There was a significant graded increase of serum sialic acid, alpha-1 acid glycoprotein, IL-6 and urinary albumin excretion rate amongst the three groups, with the lowest levels in non-diabetic subjects, intermediate levels in NIDDM patients without syndrome X and highest levels in NIDDM patients with syndrome X. C-reactive protein and cortisol levels were also higher in syndrome X-positive compared to X-negative patients and serum amyloid A was higher in both diabetic groups than in the control group. We conclude that NIDDM is associated with an elevated acute-phase response, particularly in those with features of syndrome X. Abnormalities of the innate immune system may be a contributor to the hypertriglyceridaemia, low HDL cholesterol, hypertension, glucose intolerance, insulin resistance and accelerated atherosclerosis of NIDDM. Microalbuminuria may be a component of the acute-phase response.
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PMID:NIDDM as a disease of the innate immune system: association of acute-phase reactants and interleukin-6 with metabolic syndrome X. 2212 8

We evaluated the relationship between plasma fibrinogen concentration and the serum levels of interleukin-6 (IL-6), its soluble receptor, and their complex in patients with type 2 diabetes mellitus. The study comprised 57 patients with type 2 diabetes and 15 normal healthy controls. Serum levels of IL-6, soluble IL-6 receptor (IL-6R), and circulating IL-6/IL-6R complex were determined by enzyme-linked immunosorbent assays. Correlations between the different study parameters and serum IL-6, IL-6R, or IL-6/IL-6R complex levels were determined by multiple linear regression analysis. Any association between the different study parameters and the serum levels of IL-6, IL-6R, or IL-6/IL-6R complex were determined by stepwise linear regression analysis. The serum IL-6 level in diabetic subjects was significantly higher than in normal healthy controls (3.48 +/- 3.29 pg/ml vs 0.784 +/- 0.90 pg/ml, mean +/- SD, respectively, P = 0.0001). The specific optical density of the serum IL-6/IL-6R complex in diabetic patients was also significantly higher than in normal healthy controls, although there was no significant difference in the serum IL-6R level between diabetic patients and controls. The serum IL-6 concentration was correlated significantly with the HbA(1C) level (beta = 0.58, P = 0. 04) by multiple regression analysis. Stepwise regression analysis revealed that the levels of serum IL-6 (F = 8.251), HbA(1C) (F = 1. 08), and serum urea nitrogen (F = 5.603) were associated with the plasma fibrino gen concentration. These results suggest that hyperglycaemia and increased levels of serum IL-6 can increase the plasma fibrinogen concentration, one of the known risk factors for atherosclerosis in patients with type 2 diabetes mellitus.
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PMID:Circulating levels of interleukin-6, its soluble receptor and interleukin-6/interleukin-6 receptor complexes in patients with type 2 diabetes mellitus. 1043 55

Type 2 diabetes is associated with increased circulating concentrations of markers of the acute-phase response and interleukin-6 (IL-6). An augmented acute-phase response may be a mechanism which explains many of the clinical and biochemical features of type 2 diabetes and its complications. We sought to confirm that circulating concentrations of the cytokine acute-phase mediators IL-6 and tumour necrosis factor alpha [TNFalpha] are elevated in type 2 diabetes, and investigated blood as a source of cytokines in type 2 diabetes. Blood samples from 20 type 2 diabetic and 17 age-matched healthy subjects were incubated in vitro for 24 hr with and without lipopolysaccharide (LPS) stimulation and secreted cytokines measured. Plasma IL-6 and TNFalpha were significantly increased in type 2 diabetes compared to normal subjects. However, basal production of IL-6 and TNFalpha in cultured diabetic blood was markedly depressed in comparison with non-diabetic samples. IL-6 and TNFalpha production was increased in blood in response to LPS, reaching similar levels in diabetic and non-diabetic subjects, though IL-6 was slightly but significantly higher in controls. We conclude that circulating levels of IL-6 and TNFalpha are increased in type 2 diabetes but there is downregulation of basal cytokine production in blood cells in type 2 diabetes. Blood has the capacity to produce cytokines in diabetes which contribute to the augmented acute-phase response, but the main source of the increased plasma IL-6 and TNFalpha concentrations may be from non-circulating cells.
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PMID:Plasma interleukin-6, tumour necrosis factor alpha and blood cytokine production in type 2 diabetes. 1098 73

Diabetes mellitus may be associated with intracellular glutathione (GSH) deficiency. Since in vivo studies have shown that plasma intracellular GSH plays a key role in regulating the activation of nuclear factor kappaB (NF-kappaB), we have investigated the relationship between intracellular thiols (GSH, homocysteine, cysteine and cysteinyglycine) and NF-kappaB activity in the peripheral blood mononuclear cells (PBMC) of 63 elderly non-insulin dependent diabetes mellitus (NIDDM) patients (28 microalbuminurics and 35 normoalbuminurics) and 30 healthy age- and sex-matched subjects. In addition, we have measured plasma concentrations of these thiol compounds, serum concentrations of interleukin-6 (IL-6) and vascular cell adhesion molecule-1 (sVCAM-1), that are partly dependent on the NF-kappaB activation, as well as the serum levels of thiobarbituric acid reacting substances (TBARS), as index of lipid peroxidation. Diabetic patients with microalbuminuria (MAB) and normoalbuminuria had NF-kappaB activity 2.1- and 1.5-fold greater, respectively, than the control group. As compared to normoalbuminuric patients, patients with MAB had significantly higher levels of glycemia, plasma homocysteine, and serum concentrations of TBARS, IL-6 and sVCAM-1 (in all cases, p < 0.01), and significantly lower GSH content in the PBMC (p < 0.05). The intracellular GSH in PBMC correlated with NF-kappaB activation (r = -0.82; p < 0.0001), serum TBARS (r = -0.60; p < 0.001), and with fasting glycemia (r = -0.56; p < 0.001) in patients with MAB, whereas a weaker association between GSH levels in PBMC and NF-kappaB activation (r = -0.504, p < 0.001) was seen in patients without MAB. These results suggest that the decrease of intracellular GSH content in elderly NIDDM patients with MAB is strongly associated with enhanced NF-kappaB activation, which could contribute to the development of increased glomerular capillary permeability and its rapid progression.
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PMID:Intracellular glutathione deficiency is associated with enhanced nuclear factor-kappaB activation in older non-insulin dependent diabetic patients. 1181 38

The reason for the elevation of fibrinogen concentration in diabetic patients with nephropathy is not known so far. In order to elucidate the mechanism of such an increase in fibrinogen levels, we investigated haemorheological and inflammatory markers in type 2 diabetic patients in a cross-sectional design. Thirty-two non-smoking type 2 diabetic patients (13 women, 19 men; body mass index 29.1+/-5.4 kg/m2, age 62.8+/-12.1 years) were investigated. Patients with C-reactive protein levels >1.5 mg/dl were excluded from the study. Concentration of fibrinogen was measured by immunonephelometry, C-reactive protein by immunoturbidimetry, and interleukin-6 (IL-6) by an enzyme-linked immunosorbent assay, and viscosity of plasma and of whole blood was determined by rotation viscosimetry. Concentrations of inflammatory parameters were well correlated with each other (p<0.05 for all correlations): IL-6 with C-reactive protein (r=0.48), and C-reactive protein with fibrinogen (r=0.41). While no associations were found with concentrations of C-reactive protein or IL-6, urinary albumin excretion was correlated with erythrocyte sedimentation rate (r=0.47) and with fibrinogen concentration (r=0.39; p<0.05). In patients with type 2 diabetes mellitus, urinary albumin excretion was not associated with concentrations of IL-6 or C-reactive protein. These results suggest an IL-6-independent mechanism for increased fibrinogen levels and erythrocyte sedimentation rate in type 2 diabetic patients with increased urinary albumin excretion.
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PMID:Lack of an association of urinary albumin excretion with interleukin-6 or C-reactive protein in patients with type 2 diabetes. 1185 92

Both infections and injuries activate the immunity system, leading to a series of metabolic changes which place the organism at a disadvantage and contribute to its elimination, thus facilitating the repair of the injured tissue. The study of the actions of tumour necrosing factor alpha (TNF-alpha) and interleukin-6 (IL-6), classically implicated in inflammatory processes and in fighting infection, has revealed numerous metabolic effects. Some gene polymorphisms of TNF-alpha and IL-6 (associated with a different TNF-alpha or IL-6 transcription rate) and the plasma concentrations of the soluble TNF-alpha receptor are found to be simultaneously associated with resistance to insulin, the proportion of body fat and with the mortality linked with different chronic infections. Therefore, it seems that the immune system is designed to fight infections effectively and to provide certain survival advantages during periods of intermittent fasting so frequent in the past. By inducing a resistance to insulin in the muscles, the energy substrates would thus be reserved for neuronal metabolism. In the presence of an insulin-resistance genotype and a westernization of the environment (carbohydrate-rich diet, an increase in saturated fat, low fibre and sedentary lifestyle), a genotype with a high cytokine response will contribute to a worsening of the resistance to insulin and, finally, to type 2 diabetes mellitus and atherosclerosis. The advantages for our ancestors of a large cytokine response (eradication of the lesion) or moderate resistance to insulin (protection against food shortage) have led in the present day to the development of atherosclerosis now that the characteristics of the environment have changed. It is contended that these changes constitute examples of good adaptation to the environment or poor concordance between our current lifestyle and our genome.
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PMID:[Insulin resistance and evolution]. 1192 38

It is widely accepted that increasing adiposity is associated with insulin resistance and increased risk of type 2 diabetes. The predominant paradigm used to explain this link is the portal/visceral hypothesis. This hypothesis proposes that increased adiposity, particularly in the visceral depots, leads to increased free fatty acid flux and inhibition of insulin action via Randle's effect in insulin-sensitive tissues. Recent data do not entirely support this hypothesis. As such, two new paradigms have emerged that may explain the established links between adiposity and disease. (A) Three lines of evidence support the ectopic fat storage syndrome. First, failure to develop adequate adipose tissue mass in either mice or humans, also known as lipodystrophy, results in severe insulin resistance and diabetes. This is thought to be the result of ectopic storage of lipid into liver, skeletal muscle, and the pancreatic insulin-secreting beta cell. Second, most obese patients also shunt lipid into the skeletal muscle, the liver, and probably the beta cell. The importance of this finding is exemplified by several studies demonstrating that the degree of lipid infiltration into skeletal muscle and liver correlates highly with insulin resistance. Third, increased fat cell size is highly associated with insulin resistance and the development of diabetes. Increased fat cell size may represent the failure of the adipose tissue mass to expand and thus to accommodate an increased energy influx. Taken together, these three observations support the acquired lipodystrophy hypothesis as a link between adiposity and insulin resistance. (B) The endocrine paradigm developed in parallel with the ectopic fat storage syndrome hypothesis. Adipose tissue secretes a variety of endocrine hormones, such as leptin, interleukin-6, angiotensin II, adiponectin (also called ACRP30 and adipoQ), and resistin. From this viewpoint, adipose tissue plays a critical role as an endocrine gland, secreting numerous factors with potent effects on the metabolism of distant tissues. These two new paradigms provide a framework to advance our understanding of the pathophysiology of the insulin-resistance syndrome.
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PMID:Increased fat intake, impaired fat oxidation, and failure of fat cell proliferation result in ectopic fat storage, insulin resistance, and type 2 diabetes mellitus. 1207 64

It has recently been demonstrated that the marked increase in the systemic concentration of cytokine interleukin-6 (IL-6) seen with exercise originates from the contracting limb and that skeletal muscle cells per se are the likely source of the production. This review summarizes the possible mechanisms for activation and biological consequences of muscle-derived IL-6. It appears that intramuscular IL-6 is stimulated by complex signaling cascades initiated by both calcium (Ca2+) -dependent and -independent stimuli. It also seems likely that skeletal muscle produces IL-6 to aid in maintaining metabolic homeostasis during periods of altered metabolic demand such as muscular exercise or insulin stimulation. It may do so via local and/or systemic effects. This review also explores the efficacy that IL-6 may be used as a therapeutic drug in treating metabolic disorders such as obesity, type 2 diabetes, and atherosclerosis.
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PMID:Muscle-derived interleukin-6: mechanisms for activation and possible biological roles. 1220 25

Previous studies have shown that renal function in type 2 diabetes correlates better with tubular changes than with glomerular pathology. Since advanced glycation end products (AGEs; AGE-albumin) and in particular carboxymethyllysine (CML) are known to play a central role in diabetic nephropathy, we studied the activation of nuclear factor kappaB (NF-kappaB) in tubular epithelial cells in vivo and in vitro by AGE-albumin and CML. Urine samples from healthy control subjects (n = 50) and type 2 diabetic patients (n = 100) were collected and tested for excretion of CML and the presence of proximal tubular epithelial cells (pTECs). CML excretion was significantly higher in diabetic patients than in healthy control subjects (P < 0.0001) and correlated with the degree of albuminuria (r = 0.7, P < 0.0001), while there was no correlation between CML excretion and HbA(1c) (r = 0.03, P = 0.76). Urine sediments from 20 of 100 patients contained pTECs, evidenced by cytokeratin 18 positivity, while healthy control subjects (n = 50) showed none (P < 0.0001). Activated NF-kappaB could be detected in the nuclear region of excreted pTECs in 8 of 20 patients with pTECs in the urine sediment (40%). Five of eight NF-kappaBp65 antigen-positive cells stained positive for interleukin-6 (IL-6) antigen (62%), while only one of the NF-kappaB-negative cells showed IL-6 positivity. pTECs in the urine sediment correlated positively with albuminuria (r = 0.57, P < 0.0001) and CML excretion (r = 0.55, P < 0.0001). Immunohistochemistry in diabetic rat kidneys and a human diabetic kidney confirmed strong expression of NF-kappaB in tubular cells. To further prove an AGE/CML-induced NF-kappaB activation in pTECs, NF-kappaB activation was studied in cultured human pTECs by electrophoretic mobility shift assays (EMSAs) and Western blot. Stimulation of NF-kappaB binding activity was dose dependent and was one-half maximal at 250 nmol/l AGE-albumin or CML and time dependent at a maximum of activation after 4 days. Functional relevance of the observed NF-kappaB activation was demonstrated in pTECs transfected with a NF-kappaB-driven luciferase reporter plasmid and was associated with an increased release of IL-6 into the supernatant. The AGE- and CML-dependent activation of NF-kappaBp65 and NF-kappaB-dependent IL-6 expression could be inhibited using the soluble form of the receptor for AGEs (RAGE) (soluble RAGE [sRAGE]), RAGE-specific antibody, or the antioxidant thioctic acid. In addition transcriptional activity and IL-6 release from transfected cells could be inhibited by overexpression of the NF-kappaB-specific inhibitor kappaBalpha. The findings that excreted pTECs demonstrate activated NF-kappaB and IL-6 antigen and that AGE-albumin and CML lead to a perpetuated activation of NF-kappaB in vitro infer that a perpetuated increase in proinflammtory gene products, such as IL-6, plays a role in damaging the renal tubule.
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PMID:Activation of tubular epithelial cells in diabetic nephropathy. 1245 11

Interleukin-6 (IL-6) is a pleiotropic cytokine expressed in many tissues. IL-6 null mice show low energy expenditure, but the effect of the variants of the IL-6 gene on energy expenditure has not been previously studied in humans. Therefore, we investigated the effect of the C-174G promoter polymorphism of the IL-6 gene on energy expenditure, measured by indirect calorimetry in healthy Finnish subjects (n = 124). We also measured insulin sensitivity by the hyperinsulinemic-euglycemic clamp. Subjects with the C-174C genotype of the IL-6 gene had significantly lower energy expenditure than subjects with the G-174C or G-174G genotypes both in fasting (CC 13.68 +/- 1.98, CG 14.73 +/- 1.57, GG 14.81 +/- 2.01 kcal x kg(-1) x min(-1); P = 0.012) and during the euglycemic-hyperinsulinemic clamp (CC 15.24 +/- 2.05, CG 16.62 +/- 2.06, GG 16.66 +/- 2.50 kcal x kg(-1) x min(-1); P = 0.007). Moreover, subjects homozygous for the C allele had lower rates of whole-body glucose uptake than carriers of the G allele (CC 50.95 +/- 13.91, CG 59.40 +/- 14.17, GG 59.21 +/- 15.93 micro mol x kg(-1) x min(-1); P = 0.016). The rates of both oxidative (P = 0.013) and nonoxidative (P = 0.016) glucose disposal were significantly affected by the IL-6 promoter polymorphism. In conclusion, the C-174C promoter polymorphism of the IL-6 gene influences energy expenditure and insulin sensitivity in healthy normoglycemic subjects. Whether this polymorphism is a risk factor for obesity or type 2 diabetes can be estimated only in prospective population-based studies.
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PMID:The C-174G promoter polymorphism of the IL-6 gene affects energy expenditure and insulin sensitivity. 1254 Jun 35


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