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Nathan Goodyear

Inflammation and insulin resistance 10.1016/j.febslet.2007.11.057 : FEBS Letters | Scie... - 0 views

www.sciencedirect.com/...S0014579307012082

inflammation insulin resistance IR PPAR TNF-alpha IL-6 IL-10 IL-1Beta JNK GLT-4 Resistin adiponectin Gherlin NF-kapppB iNOS lkkb obesity TLR-4

shared by Nathan Goodyear on 10 Jan 12 - No Cached
  • A subsequent study by Yuan et al. showed that Tnf treatment of 3T3L1 adipocytes induces insulin resistance and that this could be prevented by pretreatment of cells with aspirin
  • Activation of the Tnf receptor results in stimulation of NFκB signaling via Ikkb
  • Insulin is a pleiotropic hormone
  • ...25 more annotations...
  • the percentage of macrophages in a given adipose tissue depot is positively correlated with adiposity and adipocyte size
  • Il-10 is an anti-inflammatory cytokine produced by macrophages and lymphocytes
  • Il-10 exerts its anti-inflammatory activity by inhibiting Tnf-induced NFκB activation by reducing IKK activity [38]
  • adipose tissue macrophages are responsible for nearly all adipose tissue Tnf expression and a significant portion of Nos2 and Il6 expression
  • One theory holds that the expansion of adipose tissue leads to adipocyte hypertrophy and hyperplasia and that large adipocytes outstrip the local oxygen supply leading to cell autonomous hypoxia with activation of cellular stress pathways
  • The use of the anti-inflammatory compounds, salicylate and its derivative aspirin, for treating symptoms of T2DM dates back over 100 years
  • elevated levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin (IL-8) have all been reported in various diabetic and insulin resistant states
  • overnutrition and obesity are often accompanied by elevations in tissue and circulating FFA concentrations, and saturated FFAs can directly activate pro-inflammatory responses
  • Adipokines such as resistin, leptin and adiponectin, which are secreted by adipocytes, can also affect inflammation and insulin sensitivity
  • In skeletal muscle insulin promotes glucose uptake by stimulating translocation of the GLUT4 glucose transporter
  • macrophages are also capable of undergoing a phenotypic switch from an M1 state, which was defined as the “classically activated” pro-inflammatory macrophage, to the M2 state or the “alternatively activated” non-inflammatory cell
  • saturated fatty acids are the most potent inducers of this inflammatory response
  • Several inducers of insulin resistance, including FFAs, pro-inflammatory cytokines and oxidative stress, activate the expression of Nos2, the gene that encodes iNOS (reviewed in [33]
  • Adipose tissue insulin signaling results in decreased hormone sensitive lipase activity and this anti-lipolytic effect inhibits free fatty acid (FFA) efflux out of adipocytes.
  • In the liver, insulin inhibits the expression of key gluconeogenic enzymes and, therefore, insulin resistance in liver leads to elevated hepatic glucose production
  • elevated JNK activity in liver, adipose tissue and skeletal muscle of obese insulin resistant mice, and knockout of Jnk1 (Jnk1−/−) leads to amelioration of insulin resistance in high fat diet
  • Adipose tissue from obese mice contains proportionately more M1 macrophages, whereas, lean adipose tissue contains more M2 macrophages, and increased M1 content positively correlates with inflammation, macrophage infiltration and insulin resistance
  • C-reactive protein (CRP)
  • these studies highlight the possibility that increased iNOS activity plays a direct role in the pathogenesis of insulin resistance
  • the important role of Ikkb in the development of obesity and inflammation-induced insulin resistance.
  • It is probable that local concentrations of inflammatory mediators, such as FFAs, Tnf or other cytokines/adipokines contribute to this polarity switch
  • Tnf and other cytokines/chemokines are symptomatic of inflammation, and while they propagate and/or maintain the inflammatory state, they are not the initial cause(s) of inflammation
  • Tlr4, in particular, is stimulated by lipopolysaccharide (LPS), an endotoxin released by gram-negative bacteria
  • Tlr4 belongs to the family of Toll-like receptors that function as pattern recognition receptors that guard against microorganismal infections as part of the innate immune system.
  • Tlr4 stimulation results in the activation of both Ikkb/NFκB and JNK/AP-1 signaling, culminating in the expression and secretion of pro-inflammatory cytokines/chemokines, including, Il1b, IL-6, Tnf, Mcp1, etc. (reviewed in [57
  • Nathan Goodyear on 10 Jan 12
     
    Great review of all the known components in the inflammation, insulin resistance link
Nathan Goodyear

The adipose tissue metabolism: role of testosterone and dehydroepiandrosterone. - PubMe... - 0 views

www.ncbi.nlm.nih.gov/...10997611

Testosterone DHEA lipoprotein lipase adipose tissue hormones

shared by Nathan Goodyear on 17 Jun 15 - No Cached
  • T inhibits lipid uptake and lipoprotein-lipase (LDL) activity in adipocytes, and stimulates lipolysis
  • T inhibits differentiation of adipocyte precursor cells
  • DHEA stimulates resting metabolic rate (RMR) and lipid oxidation, and enhances glucose disposal, by increasing the expression of GLUT-1 and GLUT-4 on fat cell plasma membrane
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  • The insulin-like effect of DHEA would be associated to a decrease of plasma insulin concentrations and, thus, to an increase of the molar ratio between lipolytic hormones and insulin
  • the fat-reducing effect of both T and DHEA seems to be more evident at the level of visceral adipose tissue
  • Nathan Goodyear on 17 Jun 15
     
    Testosterone inhibits lipid uptake into adipocytes.  Testosterone inhibits lipoprotein lipase.  Testosterone stimulated lipolysis.  Testosterone inhibits adipocyte differentiation of proginator cells. DHEAs effects are through different mechanisms.   Both have a preference for activity with visceral adipose tissue.
Nathan Goodyear

Adipocyte dysfunctions linking obesity to insulin resistance and type 2 diabetes - 0 views

www.ncbi.nlm.nih.gov/...PMC2886982

obesity insulin resistance diabetes inflammation adipocyte dysfunction adipose tissue

shared by Nathan Goodyear on 22 Dec 11 - No Cached
  • Nathan Goodyear on 22 Dec 11
     
    Great explanation of current understanding of how adipocyte dysfunction leads to inflammation, increase FFA, insulin resistance, obesity, and associated inflammatory conditions such as diabetes
Nathan Goodyear

Increase in Glucose-6-Phosphate Dehydrogenase in Adipocytes Stimulates Oxidative Stress... - 0 views

diabetes.diabetesjournals.org/...2939

G6PD obesity insulin resistance adipocytes

shared by Nathan Goodyear on 10 Jan 19 - No Cached
  • Nathan Goodyear on 10 Jan 19
     
    G6PD as a marker of obesity and IR. G6PD is produced from adipocytes.
Nathan Goodyear

Toll-like receptor signaling links dietary fatty acids to the metabolic syndrome - 0 views

www.ncbi.nlm.nih.gov/...PMC3099529

TLR toll-like receptors toll-like receptors fatty acids fat metabolic syndrome obesity overweight inflammation dietary

shared by Nathan Goodyear on 08 Oct 12 - No Cached
  • Activation of the innate immune system controls macronutrient metabolism
  • the innate immune response is the first line of defense against invading pathogens, wherein highly conserved pathogen-associated molecular patterns (PAMPs) are recognized by cognate pattern recognition receptors (PRRs
  • many studies have supported the idea that cytokine signaling directly promotes insulin resistance
  • ...10 more annotations...
  • innate immune system may be causally linked to obesity
  • adipose tissue contains a substantial population of macrophages, and macrophage-driven adipose inflammation contributes significantly to the pathogenesis of obesity
  • Collectively, activation of the innate immune system is strongly associated with ASCVD, insulin resistance, and obesity, and recent evidence suggests that much of this association can be traced to a unique family of PRRs known as TLRs
  • TLRs are a family of type I transmembrane receptors, currently thought to comprise at least 13 members in mammals, that specifically recognize a variety of microbial PAMPs and trigger host cellular responses
  • Free SFAs have indeed been demonstrated to elicit TLR4-dependent and TLR2-dependent responses in several cell types.
  • Endogenous SFAs released from adipocytes activate cocultured macrophages via TLR4 [18], indicating the potential for cellular crosstalk in adipose tissue. Collectively, there is a growing body of evidence that SFAs promote, whereas long chain PUFA antagonize, TLR4-dependent and TLR2-dependent signaling in multiple cell models
  • In an elegant study, Shi et al. [16] demonstrated that SFAs activate TLR4-dependent signaling in both macrophages and adipocytes, and mice lacking TLR4 are protected against insulin resistance driven by intravenous lipid infusion
  • In addition to effects in macrophages and adipocytes, SFAs can activate TLR4 in the hypothalamus, which triggers a central inflammatory response that results in resistance to anorexigenic signals
  • endogenous SFAs can indeed promote innate immunity and inflammatory disease
  • This finding strongly supports the work of Hwang and coworkers [19–22] demonstrating that ω-3 PUFAs can effectively counteract SFA-induced TLR4 activation in cultured macrophages and dendritic cells.
  • Nathan Goodyear on 08 Oct 12
     
    high dietary fatty acids linked to metabolic syndrome through TLR.
Nathan Goodyear

Testosterone: a metabolic hormone in health and disease - 0 views

joe.endocrinology-journals.org/...R25.full

male hormone hormones testosterone hypogonadal-obesity-adipocytokine hypothesis

shared by Nathan Goodyear on 08 May 13 - No Cached
  • E2 and the inflammatory adipocytokines tumour necrosis factor α (TNFα) and interleukin 6 (IL6) inhibit hypothalamic production of GNRH and subsequent release of LH and FSH from the pituitary
  • Leptin, an adipose-derived hormone with a well-known role in regulation of body weight and food intake, also induces LH release under normal conditions via stimulation of hypothalamic GNRH neurons
  • In human obesity, whereby adipocytes are producing elevated amounts of leptin, the hypothalamic–pituitary axis becomes leptin resistant
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  • there is evidence from animal studies that leptin resistance, inflammation and oestrogens inhibit neuronal release of kisspeptin
  • Beyond hypothalamic action, leptin also directly inhibits the stimulatory action of gonadotrophins on the Leydig cells of the testis to decrease testosterone production; therefore, elevated leptin levels in obesity may further diminish androgen status
  • increasing insulin resistance assessed by glucose tolerence test and hypoglycemic clamp was shown to be associated with a decrease in Leydig cell testosterone secretion in men
  • ADT for the treatment of prostatic carcinoma in some large epidemiological studies has been shown to be associated with an increased risk of developing MetS and T2DM
  • Non-diabetic men undergoing androgen ablation show increased occurrence of new-onset diabetes and demonstrate elevated insulin levels and worsening glycaemic control
  • Prostate cancer patients with pre-existing T2DM show a further deterioration of insulin resistance and worsening of diabetic control following ADT
  • The response to testosterone replacement of insulin sensitivity is in part dependent on the androgen receptor (AR)
  • Low levels of testosterone have been associated with an atherogenic lipoprotein profile, characterised by high LDL and triglyceride levels
  • a positive correlation between serum testosterone and HDL has been reported in both healthy and diabetic men
  • up to 70% of the body's insulin sensitivity is accounted for by muscle
  • Testosterone deficiency is associated with a decrease in lean body mass
  • relative muscle mass is inversely associated with insulin resistance and pre-diabetes
  • GLUT4 and IRS1 were up-regulated in cultured adipocytes and skeletal muscle cells following testosterone treatment at low dose and short-time incubations
  • local conversion of testosterone to DHT and activation of AR may be important for glucose uptake
  • inverse correlation between testosterone levels and adverse mitochondrial function
  • orchidectomy of male Wistar rats and associated testosterone deficiency induced increased absorption of glucose from the intestine
  • (Kelley & Mandarino 2000). Frederiksen et al. (2012a) recently demonstrated that testosterone may influence components of metabolic flexibility as 6 months of transdermal testosterone treatment in aging men with low–normal bioavailable testosterone levels increased lipid oxidation and decreased glucose oxidation during the fasting state.
  • Decreased lipid oxidation coupled with diet-induced chronic FA elevation is linked to increased accumulation of myocellular lipid, in particular diacylglycerol and/or ceramide in myocytes
  • In the Chang human adult liver cell line, insulin receptor mRNA expression was significantly increased following exposure to testosterone
  • Testosterone deprivation via castration of male rats led to decreased expression of Glut4 in liver tissue, as well as adipose and muscle
  • oestrogen was found to increase the expression of insulin receptors in insulin-resistant HepG2 human liver cell line
  • FFA decrease hepatic insulin binding and extraction, increase hepatic gluconeogenesis and increase hepatic insulin resistance.
  • Only one, albeit large-scale, population-based cross-sectional study reports an association between low serum testosterone concentrations and hepatic steatosis in men (Völzke et al. 2010)
  • This suggests that testosterone may confer some of its beneficial effects on hepatic lipid metabolism via conversion to E2 and subsequent activation of ERα.
  • hypogonadal men exhibiting a reduced lean body mass and an increased fat mass, abdominal or central obesity
  • visceral adipose tissue was inversely correlated with bioavailable testosterone
  • there was no change in visceral fat mass in aged men with low testosterone levels following 6 months of transdermal TRT, yet subcutaneous fat mass was significantly reduced in both the thigh and the abdominal areas when analysed by MRI (Frederiksen et al. 2012b)
  • ADT of prostate cancer patients increased both visceral and subcutaneous abdominal fat in a 12-month prospective observational study (Hamilton et al. 2011)
  • Catecholamines are the major lipolysis regulating hormones in man and regulate adipocyte lipolysis through activation of adenylate cyclase to produce cAMP
  • deficiency of androgen action decreases lipolysis and is primarily responsible for the induction of obesity (Yanase et al. 2008)
  • may be some regional differences in the action of testosterone on subcutaneous and visceral adipose function
  • proinflammatory adipocytokines IL1, IL6 and TNFα are increased in obesity with a downstream effect that stimulates liver production of CRP
  • observational evidence suggests that IL1β, IL6, TNFα and CRP are inversely associated with serum testosterone levels in patients
  • TRT has been reported to significantly reduce these proinflammatory mediators
  • This suggests a role for AR in the metabolic actions of testosterone on fat accumulation and adipose tissue inflammatory response
  • testosterone treatment may have beneficial effects on preventing the pathogenesis of obesity by inhibiting adipogenesis, decreasing triglyceride uptake and storage, increasing lipolysis, influencing lipoprotein content and function and may directly reduce fat mass and increase muscle mass
  • Early interventional studies suggest that TRT in hypogonadal men with T2DM and/or MetS has beneficial effects on lipids, adiposity and parameters of insulin sensitivity and glucose control
  • Evidence that whole-body insulin sensitivity is reduced in testosterone deficiency and increases with testosterone replacement supports a key role of this hormone in glucose and lipid metabolism
  • Impaired insulin sensitivity in these three tissues is characterised by defects in insulin-stimulated glucose transport activity, in particular into skeletal muscle, impaired insulin-mediated inhibition of hepatic glucose production and stimulation of glycogen synthesis in liver, and a reduced ability of insulin to inhibit lipolysis in adipose tissue
  • Nathan Goodyear on 08 May 13
     
    Great review of the Hypogonadal-obesity-adipocytokine hypothesis.
Nathan Goodyear

Figure 1 : Adipocyte dysfunctions linking obesity to insulin resistance and t... - 0 views

www.nature.com/...nrm2391_F1.html

obesity insulin resistance diabetes adipose tissue inflammation TNF-alpha FFA

shared by Nathan Goodyear on 22 Dec 11 - No Cached
  • Nathan Goodyear on 22 Dec 11
     
    nice diagram of how adipocyte dysfunction leads to inflammation and insulin resistance, and increase FFA.
Nathan Goodyear

Caloric restriction increases adiponectin expression by adipose tissue and prevents the... - 0 views

www.jnutbio.com/...abstract

calorie restriction adiponectin insulin resistance adipocytes fat tissue cells overweight obesity

shared by Nathan Goodyear on 31 Jul 12 - No Cached
  • Nathan Goodyear on 31 Jul 12
     
    Calorie restriction increases adiponectin secretion from adipocytes.  Another plus of calorie restriction.  Remember, adiponectin and insulin are inversely associated.  Granted, this is in a rat model, but still supporting the overall health benefits of calorie restriction.
Nathan Goodyear

Regulation of 11beta-HSD genes in human adipose tis... [Obes Res. 2004] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...14742837

stress cortisol cortisone obesity fat cells adipocytes adipose tissue

shared by Nathan Goodyear on 09 Mar 12 - No Cached
  • Nathan Goodyear on 09 Mar 12
     
    adipocytes increase genetic expression of 11beta-HSD. This increases local cortisol production from cortisone.  This plays a pivotal role in obesity.  Question:  would this play a role in peripheral hypothyroid?  I think so.
Nathan Goodyear

Adiponectin translation is increased by the PPARγ agonists pioglitazone and ω... - 0 views

ajpendo.physiology.org/...E480.long

n-3 omega-3 DHA EPA adiponectin PPAR-gamma obesity adipocytes fatty acids

shared by Nathan Goodyear on 13 Jun 12 - No Cached
  • Nathan Goodyear on 13 Jun 12
     
    Omeg-3, DHA and EPA, increased adiponectin production.  In addition, blockade of the PPAR-gamma resulted in a reduction in adiponectin production.  Thus PPAR gamma activation results in adiponectin production by adipocytes.
Nathan Goodyear

Dehydroepiandrosterone exerts antiglucocorticoid action on human preadipocyte prolifera... - 0 views

ajpendo.physiology.org/...E1134

DHEA 11-betaHSD1 11beta-HSD1 adipocyte glucose hormone hormones

shared by Nathan Goodyear on 14 Nov 13 - No Cached
  • Nathan Goodyear on 14 Nov 13
     
    Animal study, finds that DHEA inhibited 11beta-HSD type I and thus improved glucose uptake and adipocyte proliferation.  This effect occurred peripherally.
Nathan Goodyear

Curcumin Inhibits Adipogenesis in 3T3-L1 Adipocytes and Angiogenesis and Obesity in C57... - 0 views

jn.nutrition.org/...919.abstract

curcumin adipogenesis obesity weight loss

shared by Nathan Goodyear on 28 Apr 11 - No Cached
  • Dietary polyphenols may suppress growth of adipose tissue through their antiangiogenic activity and by modulating adipocyte metabolism
  • curcumin, the major polyphenol in turmeric spice
  • curcumin suppression of angiogenesis in adipose tissue together with its effect on lipid metabolism in adipocytes may contribute to lower body fat and body weight gain
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  • Our findings suggest that dietary curcumin may have a potential benefit in preventing obesity
  • Nathan Goodyear on 28 Apr 11
     
    Curcumin useful in obesity
Nathan Goodyear

IL-1 family in breast cancer: Potential interplay with leptin and other adipocytokines ... - 0 views

www.sciencedirect.com/...S0014579308010211

obesity Adiponectin IL-6 adipocytes Leptin inflammation cancer IL-1

shared by Nathan Goodyear on 07 Jan 21 - No Cached
  • Nathan Goodyear on 07 Jan 21
     
    Obesity is biologically active, both from a hormonal and inflammatory perspective. No matter what marketing may try to say, obesity is not a "new health". Inflammatory signaling, i.e. IL-1, IL-6... are increased from the biological adipocytes in obesity. These can lead to cancer development and progression.
Nathan Goodyear

Adrenocortical dysregulation as a major player in insulin resistance and onset of obesity - 0 views

ajpendo.physiology.org/...E1465.long

cortisol insulin resistance metabolic syndrome obesity overweight

shared by Nathan Goodyear on 14 Mar 12 - No Cached
  • acute GC secretion during stress mobilizes peripheral amino acids from muscle as well as fatty acids and glycerol from peripheral fat stores to provide substrates for glucose synthesis by the liver
  • chronically elevated GC levels alter body fat distribution and increase visceral adiposity as well as metabolic abnormalities in a fashion reminiscent of metabolic syndrome
  • This local production may play an important role in the onset of obesity and insulin resistance.
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  • In adipocytes, cortisol inhibits lipid mobilization in the presence of insulin, thus leading to triglyceride accumulation and retention.
  • Since the density of GC receptors is higher in intra-abdominal (visceral) fat than in other fat depots, the activity of cortisol leading to accumulation of fat is accentuated in visceral adipose tissue (24, 158), providing a mechanism by which excessive endogenous or exogenous GC lead to abdominal obesity and IR
  • obese patients generally have normal or subnormal plasma cortisol concentrations
  • This may be explained by an increased intratissular/cellular concentration of cortisol in adipose tissues
  • Intracellular GC may be produced from recycling of GC metabolites such as cortisone in adipose tissues
  • Local GC recycling metabolism is mediated by 11β-hydroxysteroid dehydrogenase enzymes (11β-HSD1 and 11β-HSD2
  • Cortisol also increases 11β-HSD1 expression in human adipocytes
  • In humans, elevated 11β-HSD1 expression in visceral adipose tissue is also associated with obesity
  • even if obese patients generally have normal or subnormal plasma cortisol concentrations (131, 158), triglyceride accumulation in visceral adipose tissue may be due, at least in part, to the local production of GC in insulin- and GC-responsive organs such as adipose tissue, liver, and skeletal muscle
  • Nathan Goodyear on 14 Mar 12
     
    another nice article on the dysregulation of cortisol and its role in insulin resistance, metabolic syndrome, and obesity.
Nathan Goodyear

PPARs, Obesity, and Inflammation - 0 views

www.ncbi.nlm.nih.gov/...PMC1783744

obesity inflammation PPARs perioxisome proliferator-activated receptor

shared by Nathan Goodyear on 16 Jan 12 - No Cached
  • increase of 61% within 10 years
  • Many of the inflammatory markers found in plasma of obese individuals appear to originate from adipose tissue
  • obesity is a state of chronic low-grade inflammation that is initiated by morphological changes in the adipose tissue.
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  • secretion of MCP-1, resistin, and other proinflammatory cytokines is increased by obesity, the adipose secretion of the anti-inflammatory protein adiponectin is decreased
  • the peroxisome proliferators- activated receptor (PPAR) family are involved in the regulation of inflammation and energy homestasis
  • natural agonists, including unsaturated fatty acids and eicosanoids
  • PPARα also regulates inflammatory processes, mainly by inhibiting inflammatory gene expression
  • upregulation of COX-2 is seen in alcoholic steatohepatitis and nonalcoholic steatohepatitis and has been directly linked to the progression of steatosis to steatohepatitis, the inhibitory effect of PPARα on COX-2 may reduce steatohepatitis
  • PPARα agonists have a clear anorexic effect resulting in decreased food intake, evidence is accumulating that PPARα may also directly influence adipose tissue function, including its inflammatory status.
  • PPARα may govern adipose tissue inflammation in three different ways: (1) by decreasing adipocyte hypertrophy, which is known to be connected with a higher inflammatory status of the tissue [3, 11, 59], (2) by direct regulation of inflammatory gene expression via locally expressed PPARα, or (3) by systemic events likely originating from liver
  • PPARγ is considered the master regulator of adipogenesis
  • Unsaturated fatty acids and several eicosanoids serve as endogenous agonists of PPARγ
  • PPARγ2, which is adipose-tissue specific
  • two different molecular mechanisms have been proposed by which anti-inflammatory actions of PPARγ are effectuated: (1) via interference with proinflammatory transcription factors including STAT, NF-κB, and AP-1
  • and (2) by preventing removal of corepressor complexes from gene promoter regions resulting in suppression of inflammatory gene transcription
  • diet-induced obesity is associated with increased inflammatory gene expression in adipose tissue via adipocyte hypertrophy and macrophage infiltration
  • PPARγ is able to reverse macrophage infiltration, and subsequently reduces inflammatory gene expression
  • Inflammatory adipokines mainly originate from macrophages which are part of the stromal vascular fraction of adipose tissue [18, 19], and accordingly, the downregulation of inflammatory adipokines in WAT by PPARγ probably occurs via effects on macrophages
  • By interfering with NF-κB signaling pathways, PPARγ is known to decrease inflammation in activated macrophages
  • Recent data suggest that activation of PPARγ in fatty liver may protect against inflammation
  • PPARs may influence the inflammatory response either by direct transcriptional downregulation of proinflammatory genes
  • anti-inflammatory properties of PPARs in human obesity
  • Nathan Goodyear on 16 Jan 12
     
    PPARs play pivotal in obesity.  PPARs appear to reduce the inflammatory cascade associated with obesity.  Downregulation of PPARs are associated with increased inflammation.  Natural PPARs include unsaturated fats and eicosanoids.
Nathan Goodyear

Adipose Tissue Inflammation in Obesity and Metabolic Syndrome - - Satoshi Nishimura - D... - 0 views

www.discoverymedicine.com/...obesity-and-metabolic-syndrome

inflammation obesity metabolic syndrome fat adipose tissue innate immune system humoral

shared by Nathan Goodyear on 21 Dec 11 - No Cached
  • Activation of inflammatory pathways in adipocytes impairs triglyceride storage and increases release of free fatty acids, an excess of which is known to induce insulin resistance in muscle and liver
  • recent studies have shown that large numbers of macrophages infiltrate obese adipose tissue,
  • It has been postulated that a paracrine loop involving free fatty acids and inflammatory cytokines establishes a vicious cycle between adipocytes and macrophages that propagates the inflammation
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  • not only does interrupting the accumulation of macrophages within obese adipose tissue suppresses adipose inflammation in various animal models, it also ameliorates systemic insulin resistance and metabolic abnormalities, suggesting macrophages are key effector cells involved in adipose inflammation
  • activation of the leukocyte adhesion cascade, a hallmark of inflammation
  • Thus, obese visceral adipose tissue is clearly a site of chronic inflammation
  • CD8+ T cells within obese adipose tissue induce activation and migration of monocytes/macrophages, and in cooperation with the adipose tissue, they also induce macrophage differentiation. At the same time, obese adipose tissue activates CD8+ T cells, creating a vicious cycle involving CD8+ T cells, macrophages, and obese adipose tissue that propagates local inflammation
  • In obese adipose tissue there is a shift to dominance of CD8+ and TH1 T cells, which appears to propagate inflammation
  • Nathan Goodyear on 21 Dec 11
     
    fascinating read how the immune system and resultant inflammation results in obesity.
Nathan Goodyear

Inflammatory cause of metabolic syndrome via brain stress and NF-κB - 0 views

www.ncbi.nlm.nih.gov/...PMC3314172

metabolic syndrome TLR cytokines hypothalamus brain neurology metabolic syndrome NF-kappaB DIO diet induced obesity over nutrition nutrition inflammation

shared by Nathan Goodyear on 09 Jul 13 - No Cached
  • Mechanistic studies further showed that such metabolic inflammation is related to the induction of various intracellular stresses such as mitochondrial oxidative stress, endoplasmic reticulum (ER) stress, and autophagy defect under prolonged nutritional excess
  • intracellular stress-inflammation process for metabolic syndrome has been established in the central nervous system (CNS) and particularly in the hypothalamus
  • the CNS and the comprised hypothalamus are known to govern various metabolic activities of the body including appetite control, energy expenditure, carbohydrate and lipid metabolism, and blood pressure homeostasis
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  • Reactive oxygen species (ROS) refer to a class of radical or non-radical oxygen-containing molecules that have high oxidative reactivity with lipids, proteins, and nucleic acids
  • a large measure of intracellular ROS comes from the leakage of mitochondrial electron transport chain (ETC)
  • Another major source of intracellular ROS is the intentional generation of superoxides by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase
  • there are other ROS-producing enzymes such as cyclooxygenases, lipoxygenases, xanthine oxidase, and cytochrome p450 enzymes, which are involved with specific metabolic processes
  • To counteract the toxic effects of molecular oxidation by ROS, cells are equipped with a battery of antioxidant enzymes such as superoxide dismutases, catalase, peroxiredoxins, sulfiredoxin, and aldehyde dehydrogenases
  • intracellular oxidative stress has been indicated to contribute to metabolic syndrome and related diseases, including T2D [72; 73], CVDs [74-76], neurodegenerative diseases [69; 77-80], and cancers
  • intracellular oxidative stress is highly associated with the development of neurodegenerative diseases [69] and brain aging
  • dietary obesity was found to induce NADPH oxidase-associated oxidative stress in rat brain
  • mitochondrial dysfunction in hypothalamic proopiomelanocortin (POMC) neurons causes central glucose sensing impairment
  • Endoplasmic reticulum (ER) is the cellular organelle responsible for protein synthesis, maturation, and trafficking to secretory pathways
  • unfolded protein response (UPR) machinery
  • ER stress has been associated to obesity, insulin resistance, T2D, CVDs, cancers, and neurodegenerative diseases
  • brain ER stress underlies neurodegenerative diseases
  • under environmental stress such as nutrient deprivation or hypoxia, autophagy is strongly induced to breakdown macromolecules into reusable amino acids and fatty acids for survival
  • intact autophagy function is required for the hypothalamus to properly control metabolic and energy homeostasis, while hypothalamic autophagy defect leads to the development of metabolic syndrome such as obesity and insulin resistance
  • prolonged oxidative stress or ER stress has been shown to impair autophagy function in disease milieu of cancer or aging
  • TLRs are an important class of membrane-bound pattern recognition receptors in classical innate immune defense
  • Most hypothalamic cell types including neurons and glia cells express TLRs
  • overnutrition constitutes an environmental stimulus that can activate TLR pathways to mediate the development of metabolic syndrome related disorders such as obesity, insulin resistance, T2D, and atherosclerotic CVDs
  • Isoforms TLR1, 2, 4, and 6 may be particularly pertinent to pathogenic signaling induced by lipid overnutrition
  • hypothalamic TLR4 and downstream inflammatory signaling are activated in response to central lipid excess via direct intra-brain lipid administration or HFD-feeding
  • overnutrition-induced metabolic derangements such as central leptin resistance, systemic insulin resistance, and weight gain
  • these evidences based on brain TLR signaling further support the notion that CNS is the primary site for overnutrition to cause the development of metabolic syndrome.
  • circulating cytokines can limitedly travel to the hypothalamus through the leaky blood-brain barrier around the mediobasal hypothalamus to activate hypothalamic cytokine receptors
  • significant evidences have been recently documented demonstrating the role of cytokine receptor pathways in the development of metabolic syndrome components
  • entral administration of TNF-α at low doses faithfully replicated the effects of central metabolic inflammation in enhancing eating, decreasing energy expenditure [158;159], and causing obesity-related hypertension
  • Resistin, an adipocyte-derived proinflammatory cytokine, has been found to promote hepatic insulin resistance through its central actions
  • both TLR pathways and cytokine receptor pathways are involved in central inflammatory mechanism of metabolic syndrome and related diseases.
  • In quiescent state, NF-κB resides in the cytoplasm in an inactive form due to inhibitory binding by IκBα protein
  • IKKβ activation via receptor-mediated pathway, leading to IκBα phosphorylation and degradation and subsequent release of NF-κB activity
  • Research in the past decade has found that activation of IKKβ/NF-κB proinflammatory pathway in metabolic tissues is a prominent feature of various metabolic disorders related to overnutrition
  • it happens in metabolic tissues, it is mainly associated with overnutrition-induced metabolic derangements, and most importantly, it is relatively low-grade and chronic
  • this paradigm of IKKβ/NF-κB-mediated metabolic inflammation has been identified in the CNS – particularly the comprised hypothalamus, which primarily accounts for to the development of overnutrition-induced metabolic syndrome and related disorders such as obesity, insulin resistance, T2D, and obesity-related hypertension
  • evidences have pointed to intracellular oxidative stress and mitochondrial dysfunction as upstream events that mediate hypothalamic NF-κB activation in a receptor-independent manner under overnutrition
  • In the context of metabolic syndrome, oxidative stress-related NF-κB activation in metabolic tissues or vascular systems has been implicated in a broad range of metabolic syndrome-related diseases, such as diabetes, atherosclerosis, cardiac infarct, stroke, cancer, and aging
  • intracellular oxidative stress seems to be a likely pathogenic link that bridges overnutrition with NF-κB activation leading to central metabolic dysregulation
  • overnutrition is an environmental inducer for intracellular oxidative stress regardless of tissues involved
  • excessive nutrients, when transported into cells, directly increase mitochondrial oxidative workload, which causes increased production of ROS by mitochondrial ETC
  • oxidative stress has been shown to activate NF-κB pathway in neurons or glial cells in several types of metabolic syndrome-related neural diseases, such as stroke [185], neurodegenerative diseases [186-188], and brain aging
  • central nutrient excess (e.g., glucose or lipids) has been shown to activate NF-κB in the hypothalamus [34-37] to account for overnutrition-induced central metabolic dysregulations
  • overnutrition can present the cell with a metabolic overload that exceeds the physiological adaptive range of UPR, resulting in the development of ER stress and systemic metabolic disorders
  • chronic ER stress in peripheral metabolic tissues such as adipocytes, liver, muscle, and pancreatic cells is a salient feature of overnutrition-related diseases
  • recent literature supports a model that brain ER stress and NF-κB activation reciprocally promote each other in the development of central metabolic dysregulations
  • when intracellular stresses remain unresolved, prolonged autophagy upregulation progresses into autophagy defect
  • autophagy defect can induce NF-κB-mediated inflammation in association with the development of cancer or inflammatory diseases (e.g., Crohn's disease)
  • The connection between autophagy defect and proinflammatory activation of NF-κB pathway can also be inferred in metabolic syndrome, since both autophagy defect [126-133;200] and NF-κB activation [20-33] are implicated in the development of overnutrition-related metabolic diseases
  • Both TLR pathway and cytokine receptor pathways are closely related to IKKβ/NF-κB signaling in the central pathogenesis of metabolic syndrome
  • Overnutrition, especially in the form of HFD feeding, was shown to activate TLR4 signaling and downstream IKKβ/NF-κB pathway
  • TLR4 activation leads to MyD88-dependent NF-κB activation in early phase and MyD88-indepdnent MAPK/JNK pathway in late phase
  • these studies point to NF-κB as an immediate signaling effector for TLR4 activation in central inflammatory response
  • TLR4 activation has been shown to induce intracellular ER stress to indirectly cause metabolic inflammation in the hypothalamus
  • central TLR4-NF-κB pathway may represent one of the early receptor-mediated events in overnutrition-induced central inflammation.
  • cytokines and their receptors are both upstream activating components and downstream transcriptional targets of NF-κB activation
  • central administration of TNF-α at low dose can mimic the effect of obesity-related inflammatory milieu to activate IKKβ/NF-κB proinflammatory pathways, furthering the development of overeating, energy expenditure decrease, and weight gain
  • the physiological effects of IKKβ/NF-κB activation seem to be cell type-dependent, i.e., IKKβ/NF-κB activation in hypothalamic agouti-related protein (AGRP) neurons primarily leads to the development of energy imbalance and obesity [34]; while in hypothalamic POMC neurons, it primarily results in the development of hypertension and glucose intolerance
  • the hypothalamus, is the central regulator of energy and body weight balance [
  • Nathan Goodyear on 09 Jul 13
     
    Great article chronicles the biochemistry of "over nutrition" and inflammation through NF-kappaB activation and its impact on the brain.
Nathan Goodyear

Expression and Subcellular Localization of Estrogen Receptors α and β in Huma... - 0 views

press.endocrine.org/...jc.2013-2017

ER ER alpha ER beta estrogen receptor fat

shared by Nathan Goodyear on 06 Jan 14 - No Cached
  • Nathan Goodyear on 06 Jan 14
     
    ER alpha and ER beta expressed on fetal fat cells.  The authors of this article propose that ER alpha plays the dominant in fetal adipocyte differentiation.
Nathan Goodyear

PPARγ and human metabolic disease - 0 views

www.ncbi.nlm.nih.gov/...PMC1386124

PPAR-gamma perioxisome proliferator-activated receptor disease PPAR

shared by Nathan Goodyear on 24 Jan 13 - No Cached
  • PPARα and PPARδ appear primarily to stimulate oxidative lipid metabolism
  • PPARγ is principally involved in the cellular assimilation of lipids via anabolic pathways
  • PPARs are members of the nuclear hormone receptor superfamily
  • ...7 more annotations...
  • Expression of PPARγ is highest in adipose tissue,
  • PPARγ also plays a key role in the entraining of adipose tissue lipid metabolism to nutritional state
  • Its expression is highest postprandially
  • its activation leads to upregulation of genes that mediate FA uptake and trapping
  • PPARγ may also promote futile cycling in adipocytes between triglyceride (TG) esterification and de-esterification
  • its high expression in macrophages, which are now known to infiltrate the dysfunctional adipose tissue of obese subjects
    • Nathan Goodyear
      Nathan Goodyear on 28 Aug 14
       
      PPAR gamma is associated with adipocyte differentiation and lipid storage.
  • Nathan Goodyear on 24 Jan 13
     
    review of PPAR gamma
  • Blu Electronic Cigarettes on 03 Sep 14
     
    very informative! Thanks for sharing!
Nathan Goodyear

Obesity and testicular function. [Mol Cell Endocrinol. 2010] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...19540307

obesity leydig cells Testosterone low T low Testosterone T SHBG LH leptin men male hormone hormones

shared by Nathan Goodyear on 04 Sep 14 - No Cached
  • Nathan Goodyear on 04 Sep 14
     
    This article, here only abstract available, points to low Testosterone as the effect and not the cause.  The cause being obesity.  An interesting association between leptin and low T is found.  Leptin is a hormone produced from adipocytes, this study found leptin receptors in the leydig cells of testes.  Thus, increased leptin production from increased abdominal adiposity can result in a decrease in 17,20 lyase activity and thus a direct inhibition of leydig cell Testosterone production.
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