Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The peroxisome proliferator-activated receptors (PPARs) are nuclear fatty acid receptors that have been suggested to play crucial roles in metabolic diseases such as hyperlipidemia, insulin resistance, and diabetes. The three PPAR subtypes, alpha, beta, and beta/delta, have distinct expression patterns. We have investigated the role of PPARgamma in the pathogenesis of type 2 diabetes. Heterozygous PPARgamm-deficient mice were protected from the development of insulin resistance due to adipocyte hypertrophy on a high-fat diet. A Pro12Ala polymorphism in the human PPARgamma2 gene, which has been reported to cause a reduction in PPARy activity, was associated with a decreased risk of type 2 diabetes in various ethnic groups including Japanese subjects. Consistent with these results, moderate reduction of PPARgamma activity by RXR antagonist decreased the triglyceride content of white adipose tissue (WAT)/muscle/liver, due to an increase in fatty-acid combustion and a decrease in lipogenesis, thereby ameliorating high-fat diet-induced obesity and insulin resistance. By contrast, potent activation of PPARy by thiazolidinedione (TZD) stimulated adipocyte differentiation and apoptosis, thereby preventing adipocyte hypertrophy, which is associated with the alleviation of insulin resistance, presumably due to decreases in FFA, and TNFa, and the up-regulation of adiponectin. TZD increased the triglyceride content of WAT, but decreased that of the liver/muscle, leading to the amelioration of insulin resistance at the expense of obesity. It should also be noted that TZD has an anti-atherogenic effect in vivo. Uncovering the regulatory mechanisms and transcriptional targets of PPARgamma will provide insights into the pathogenesis of metabolic syndrome and offer valuable information for rational drug design.
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PMID:[PPARgamma and metabolic syndrome]. 1759 90

Diabetic and alcoholic neuropathies are heterogeneous groups with variable lesions of axons or myelin. Their pathogenesis is complex and involves multiple pathways. To elucidate the impact of immunological factors in development of these neuropathies the expression of some cytokines in serum was studied: tumour necrosis factor a (TNF-a), monocyte chemotactic protein-1 (MCP-1) and growth-regulated oncogene alpha (GRO-alpha; CXCL1). 29 patients with type 2 diabetes, 31 with chronic alcohol abuse and 20 healthy controls were included in the study. The type of neuropathy (involvement of axon or myelin) was evaluated by electrophysiological methods (EMG and nerve conduction velocity). The cytokine level was determined by ELISA method. For statistical comparison the nonparametric Mann-Whitney test was used. The evaluated material was divided according to clinical duration of neuropathy and electrophysiological pattern. Expression of TNF-alpha in both types of neuropathy does not differ from the control material. Expression of MCP-1 was higher, but insignificantly, in patients with alcoholic neuropathy. The same concerns the demyelinating form versus axonal diabetic neuropathy. Serum level of GRO-alpha; was significantly higher in patients with alcoholic neuropathy and in cases with demyelinating form of diabetic neuropathy than in control subjects. GRO-alpha; is a potent neutrophil chemoattractant playing an important role in various primary and secondary inflammatory processes. The results suggest that GRO-alpha; may contribute to the mechanism of alcoholic neuropathy and in demyelinating form of diabetic neuropathy.
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PMID:Impact of cytokines on the pathomechanism of diabetic and alcoholic neuropathies. 1759 98

Adipose tissue secretes a wide range of hormones named adipokines, and these may play a role in obesity-related inflammation. Adiponectin is an exceptional adipokine because low plasma concentrations are associated with obesity, type 2 diabetes, and cardiovascular diseases. It has been observed that plasma adiponectin concentrations are elevated during inflammatory conditions like preeclampsia and arthritis. Nuclear factor-kappaB (NF-kappaB) is an essential transcription factor for expression of inflammation-related proteins. We have used U937 cells stably transfected to express luciferase under the control of NF-kappaB to examine if adiponectin may modulate NF-kappaB activity. Physiological concentrations of native adiponectin induced NF-kappaB activity. This effect was relatively strong compared with proinflammatory adipokines like leptin, resistin, and IL-6. The enhanced NF-kappaB activity was attributed to the high molecular weight adiponectin isoforms. NF-kappaB was not activated by mutated adiponectin that is unable to form high molecular weight complexes. Furthermore, the C-terminal fragment, globular adiponectin, markedly increased NF-kappaB reporter activity, cytokine release, and mRNA expression of inflammation marker genes, at higher levels than stimulation with TNF-alpha and lipopolysaccharide. NF-kappaB activation by globular adiponectin was not affected by antibody inhibition of toll-like receptor 4 or TNF receptors 1 and 2 but was attenuated by inhibitors of p38 MAPK, phosphatidylinositol 3-kinase, and protein kinase C. Analyses of the p65 subunit of NF-kappaB in different leukocyte cell lines showed activation of two monocytic cell lines (U937 and THP-1) by native and globular adiponectin. Our results indicate that adiponectin has proinflammatory properties in monocytic cells.
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PMID:Activation of nuclear factor-kappaB by high molecular weight and globular adiponectin. 1770 46

It is now broadly accepted that low-grade chronic inflammation associated with obesity leads to the onset of insulin resistance and type 2 diabetes mellitus. Obesity-associated inflammation is characterized by an increased abundance of macrophages in adipose tissue along with production of inflammatory cytokines. Adipose tissue macrophages (ATMs) are suspected to be the major source of inflammatory mediators such as TNF-alpha and IL-6 that interfere with adipocyte function by inhibiting insulin action. However, ATMs phenotypically resemble alternatively activated (M2) macrophages and are capable of anti-inflammatory mediator production challenging the concept that ATMs are simply the "bad guys" in obese adipose tissue. Triggers promoting ATM recruitment, ATM functions and dysfunctions, and stimuli and molecular mechanisms that drive them into becoming detrimental to their environment are subject to current research. Strategies to interfere with ATM recruitment and adverse activation could give rise to novel options for treatment and prevention of insulin resistance and type 2 diabetes mellitus.
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PMID:Adipose tissue macrophages. 1771 95

TNF-alpha plays an important role in obesity-linked insulin resistance and diabetes mellitus by activating at least two serine kinases capable of promoting negative regulation of key elements of the insulin signaling pathway. Pharmacological inhibition of TNF-alpha is currently in use for the treatment of rheumatoid and psoriatic arthritis, and some case reports have shown clinical improvement of diabetes in patients treated with the TNF-alpha blocking monoclonal antibody infliximab. The objective of this study was to evaluate the effect of infliximab on glucose homeostasis and insulin signal transduction in an animal model of diabetes. Diabetes was induced in Swiss mice by a fat-rich diet. Glucose and insulin homeostasis were evaluated by glucose and insulin tolerance tests and by the hyperinsulinemic-euglycemic clamp. Signal transduction was evaluated by immunoprecipitation and immunoblotting assays. Short-term treatment with infliximab rapidly reduced blood glucose and insulin levels and glucose and insulin areas under the curve during a glucose tolerance test. Furthermore, infliximab increased the glucose decay constant during an insulin tolerance test and promoted a significant increase in glucose infusion rate during a hyperinsulinemic-euglycemic clamp. In addition, the clinical outcomes were accompanied by improved insulin signal transduction in muscle, liver, and hypothalamus, as determined by the evaluation of insulin-induced insulin receptor, insulin receptor substrate-1, and receptor substrate-2 tyrosine phosphorylation and Akt and forkhead box protein O1 serine phosphorylation. Thus, pharmacological inhibition of TNF-alpha may be an attractive approach to treat severely insulin-resistant patients with type 2 diabetes mellitus.
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PMID:Infliximab restores glucose homeostasis in an animal model of diet-induced obesity and diabetes. 1776 68

Obesity is a leading risk factor for type 2 diabetes (T2D). Aging is associated with an increase in T2D incidence, which is not totally explained by the much lower prevalence of obesity in the elderly. Low-grade inflammation in adipose tissue (AT) contributes to insulin resistance and T2D. Thus, we determined whether inflammatory responses are up-regulated with age in AT. The results showed that visceral AT from old C57BL mice had significantly higher mRNA expression of the proinflammatory cytokines IL-1beta, IL-6, TNF-alpha, and COX-2 and lower expression of anti-inflammatory PPAR-gamma than those of young mice. We further showed that adipocytes (AD) and not stromal vascular cells including macrophages (Mphi) were the cells responsible for this higher inflammatory state of the aged AT, suggesting that the age-associated increase in AT inflammation is distinguished from that seen in obesity, in which Mphi are the main contributors. However, peritoneal Mphi of either age (young or old) produced more TNF-alpha and IL-6 after incubation in old AD-conditioned medium compared with young AD-conditioned medium. This suggests that in addition to producing more inflammatory cytokines, AD from old mice induce a higher inflammatory response in other cells. Sphingolipid ceramide was higher in old compared with young AD. Reducing ceramide levels or inhibiting NF-kappaB activation decreased cytokine production, whereas the addition of ceramide increased cytokine production in young AD to a level comparable to that seen in old AD, suggesting that ceramide-induced activation of NF-kappaB plays a key role in AT inflammation.
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PMID:Aging up-regulates expression of inflammatory mediators in mouse adipose tissue. 1787 82

Insulin resistance is an important contributor to the pathogenesis of type 2 diabetes, and obesity is a risk factor for its development, in part because adipose tissue secretes proteins, called adipokines, that may influence insulin sensitivity. Among these molecules, tumor necrosis factor (TNF)-alpha has been proposed as a link between obesity and insulin resistance because TNF-alpha is overexpressed in adipose tissues of obese animals and humans, and obese mice lacking either TNF-alpha or its receptor show protection against developing insulin resistance. Direct exposure to TNF-alpha induces a state of insulin resistance in terms of glucose uptake in myocytes and brown adipocytes because of the activation of proinflammatory pathways that impair insulin signaling at the level of the insulin receptor substrate (IRS) proteins. In this regard, the Ser(307) residue in IRS-1 has been identified as a site for the inhibitory effects of TNF-alpha in myotubes, with p38 mitogen-activated protein kinase and inhibitor kB kinase being involved in the phosphorylation of this residue. Conversely, Ser phosphorylation of IRS-2 mediated by TNF-alpha activation of mitogen-activated protein kinase was the mechanism found in brown adipocytes. Protein-Tyr phosphatase (PTP)1B acts as a physiological, negative regulator of insulin signaling by dephosphorylating the phosphotyrosine residues of the insulin receptor and IRS-1, and PTP1B expression is increased in muscle and white adipose tissue of obese and diabetic humans and rodents. Moreover, up-regulation of PTP1B expression was recently found in cells treated with TNF-alpha Accordingly, myocytes and primary brown adipocytes deficient in PTP1B are protected against insulin resistance induced by this cytokine. Furthermore, down-regulation of PTP1B activity is possible by the use of pharmacological agonists of nuclear receptors that restore insulin sensitivity in the presence of TNF-alpha. In conclusion, the lack of PTP1B in muscle and brown adipocytes increases insulin sensitivity and glucose uptake and could confer protection against insulin resistance induced by adipokines.
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PMID:Insulin resistance induced by tumor necrosis factor-alpha in myocytes and brown adipocytes. 1794 Jan 60

Visfatin, is a new adipokine, highly expressed in the visceral fat of both mice and humans. To examine whether visfatin is expressed in human peripheral monocyte-enriched mononuclear cells and whether its expression is altered in type 2 diabetes (DM2), we compared 24 DM2 women [17 overweight (BMI >25) and 7 lean (BMI<25)] to 26 healthy women (14 overweight and 12 lean), all premenopausal. Relative visfatin mRNA levels were significantly higher (approximately 3-fold) in DM2 compared to healthy control women (p<0.02), independently of the presence of overweight/obesity. Mononuclear TNF-alpha and IL-6 mRNA expression was also elevated in DM2 compared to control women (p=0.001 and p=0.004, respectively), an increase observed in both lean and overweight DM2 women. By contrast, circulating visfatin, TNF-alpha, and IL-6 levels showed no difference between DM2 and control women, while adiponectin plasma levels were significantly decreased in the DM2 women (p<0.001). Circulating visfatin and TNF-alpha levels did not differ either between the lean and the overweight subgroups of DM2 and control women, while IL-6 plasma levels were significantly higher in both overweight subgroups compared to their lean counterparts. In conclusion, visfatin, TNF-alpha, and IL-6 mRNA expressions are increased in peripheral mononuclear-monocytic cells from women with type 2 diabetes, independent of their BMI, which may enhance the effects of their adipose-derived levels and may contribute to the increased insulin resistance and atherogenic risk of these patients.
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PMID:Visfatin, TNF-alpha and IL-6 mRNA expression is increased in mononuclear cells from type 2 diabetic women. 1795 40

Reduced insulin sensitivity is a key factor in the pathogenesis of type 2 diabetes and hypertension. Skeletal muscle insulin resistance is particularly important for its major role in insulin-mediated glucose disposal. Angiotensin II (ANG II) is integral in regulating blood pressure and plays a role in the pathogenesis of hypertension. In addition, we have documented that ANG II-induced skeletal muscle insulin resistance is associated with generation of reactive oxygen species (ROS). However, the linkage between ROS and insulin resistance in skeletal muscle remains unclear. To explore potential mechanisms, we employed the transgenic TG(mRen2)27 (Ren-2) hypertensive rat, which harbors the mouse renin transgene and exhibits elevated tissue ANG II levels, and skeletal muscle cell culture. Compared with Sprague-Dawley normotensive control rats, Ren-2 skeletal muscle exhibited significantly increased oxidative stress, NF-kappaB activation, and TNF-alpha expression, which were attenuated by in vivo treatment with an angiotensin type 1 receptor blocker (valsartan) or SOD/catalase mimetic (tempol). Moreover, ANG II treatment of L6 myotubes induced NF-kappaB activation and TNF-alpha production and decreased insulin-stimulated Akt activation and GLUT-4 glucose transporter translocation to plasma membranes. These effects were markedly diminished by treatment of myotubes with valsartan, the antioxidant N-acetylcysteine, NADPH oxidase-inhibiting peptide (gp91 ds-tat), or NF-kappaB inhibitor (MG-132). Similarly, NF-kappaB p65 small interfering RNA reduced NF-kappaB p65 subunit expression and nuclear translocation and TNF-alpha production but improved insulin-stimulated phosphorylation (Ser(473)) of Akt and translocation of GLUT-4. These findings suggest that NF-kappaB plays an important role in ANG II/ROS-induced skeletal muscle insulin resistance.
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PMID:Angiotensin II-induced skeletal muscle insulin resistance mediated by NF-kappaB activation via NADPH oxidase. 1807 21

Tumor necrosis factor (TNF)-alpha and local activation of the renin-angiotensin system may contribute to insulin resistance and atherosclerosis. In this study, we investigated the involvement of these mediators in the liver. We found that the gene expression of renin-angiotensin system components, together with that of plasminogen activator inhibitor (PAI)-1, is upregulated in the liver of patients with obesity and type 2 diabetes. We next examined the role of the renin-angiotensin system on TNF-alpha-induced PAI-1 production in the nonmalignant human hepatocyte cell line THLE-5b. THLE-5b cells expressed genes encoding renin-angiotensin system components including angiotensinogen, angiotensin-converting enzyme (ACE), and angiotensin type 1 (AT(1)) receptor. ACE, angiotensinogen, and angiotensin AT(1) receptor mRNA expression were upregulated time-dependently by TNF-alpha. Moreover, angiotensin AT(1) receptor antagonist dose-dependently inhibited TNF-alpha-induced PAI-1 production. Interestingly, high-dose olmesartan, but not candesartan, reduced the increased expression of the angiotensin AT(1) receptor. These results suggest that TNF-alpha and the local renin-angiotensin system coordinately stimulate PAI-1 production in hepatocytes. Selective angiotensin AT(1) receptor antagonists inhibit both TNF-alpha- and angiotensin II-induced PAI-1 production in hepatocytes, suggesting a cross talk between both systems.
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PMID:Cross talk of tumor necrosis factor-alpha and the renin-angiotensin system in tumor necrosis factor-alpha-induced plasminogen activator inhibitor-1 production from hepatocytes. 1807 28


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