scholarly journals Evidence for activation of inflammatory lipoxygenase pathways in visceral adipose tissue of obese Zucker rats

2011 ◽  
Vol 300 (1) ◽  
pp. E175-E187 ◽  
Author(s):  
Swarup K. Chakrabarti ◽  
Yeshao Wen ◽  
Anca D. Dobrian ◽  
Banumathi K. Cole ◽  
Qian Ma ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Visceral Adipose Tissue ◽  
Genetic Model ◽  
Leukotriene B4 ◽  
Zucker Rats ◽  
Low Grade ◽  
The Metabolic Syndrome ◽  
Obese Zucker Rats ◽  
Visceral Adipose

Central obesity is associated with low-grade inflammation that promotes type 2 diabetes and cardiovascular disease in obese individuals. The 12- and 5-lipoxygenase (12-LO and 5-LO) enzymes have been linked to inflammatory changes, leading to the development of atherosclerosis. 12-LO has also been linked recently to inflammation and insulin resistance in adipocytes. We analyzed the expression of LO and proinflammatory cytokines in adipose tissue and adipocytes in obese Zucker rats, a widely studied genetic model of obesity, insulin resistance, and the metabolic syndrome. mRNA expression of 12-LO, 5-LO, and 5-LO-activating protein (FLAP) was upregulated in adipocytes and adipose tissue from obese Zucker rats compared with those from lean rats. Concomitant with increased LO gene expression, the 12-LO product 12-HETE and the 5-LO products 5-HETE and leukotriene B4 (LTB4) were also increased in adipocytes. Furthermore, upregulation of key proinflammatory markers interleukin (IL)-6, TNFα, and monocyte chemoattractant protein-1 were observed in adipocytes isolated from obese Zucker rats. Immunohistochemistry indicated that the positive 12-LO staining in adipose tissue represents cells in addition to adipocytes. This was confirmed by Western blotting in stromal vascular fractions. These changes were in part reversed by the novel anti-inflammatory drug lisofylline (LSF). LSF also reduced p-STAT4 in visceral adipose tissue from obese Zucker rats and improved the metabolic profile, reducing fasting plasma glucose and increasing insulin sensitivity in obese Zucker rats. In 3T3-L1 adipocytes, LSF abrogated the inflammatory response induced by LO products. Thus, therapeutic agents reducing LO or STAT4 activation may provide novel tools to reduce obesity-induced inflammation.

scholarly journals Visceral obesity, metabolic syndrome, insulin resistance and cancer

2011 ◽  
Vol 71 (1) ◽  
pp. 181-189 ◽  
Author(s):  
Suzanne L. Doyle ◽  
Claire L. Donohoe ◽  
Joanne Lysaght ◽  
John V. Reynolds
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Adipose Tissue ◽  
Systemic Inflammation ◽  
Visceral Adipose Tissue ◽  
Tumour Progression ◽  
Visceral Adiposity ◽  
Oesophageal Adenocarcinoma ◽  
The Metabolic Syndrome ◽  
Visceral Adipose

This paper presents emerging evidence linking visceral adiposity and the metabolic syndrome (MetSyn) with carcinogenesis. The link between obesity and cancer has been clearly identified in a multitude of robust epidemiological studies. Research is now focusing on the role of visceral adipose tissue in carcinogenesis; as it is recognised as an important metabolic tissue that secretes factors that systemically alter the immunological, metabolic and endocrine milieu. Excess visceral adipose tissue gives rise to a state of chronic systemic inflammation with associated insulin resistance and dysmetabolism, collectively known as the MetSyn. Prospective cohort studies have shown associations between visceral adiposity, the MetSyn and increased risk of breast cancer, colorectal cancer and oesophageal adenocarcinoma. Furthermore, visceral adiposity and the MetSyn have been associated with increased tumour progression and reduced survival. The mechanisms by which visceral adiposity and the MetSyn are thought to promote tumorigenesis are manifold. These include alterations in adipokine secretion and cell signalling pathways. In addition, hyperinsulinaemia, subsequent insulin resistance and stimulation of the insulin-like growth factor-1 axis have all been linked with visceral adiposity and promote tumour progression. Furthermore, the abundance of inflammatory cells in visceral adipose tissue, including macrophages and T-cells, create systemic inflammation and a pro-tumorigenic environment. It is clear from current research that excess visceral adiposity and associated dysmetabolism play a central role in the pathogenesis of certain cancer types. Further research is required to elucidate the exact mechanisms at play and identify potential targets for intervention.

scholarly journals Mediterranean diet, endothelial function and vascular inflammatory markers

2006 ◽  
Vol 9 (8A) ◽  
pp. 1073-1076 ◽  
Author(s):  
Katherine Esposito ◽  
Miryam Ciotola ◽  
Dario Giugliano
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Adipose Tissue ◽  
Endothelial Dysfunction ◽  
Low Grade ◽  
The Metabolic Syndrome ◽  
Inflammatory State ◽  
Triggering Factor ◽  
Inflammatory Milieu ◽  
Visceral Adipose

AbstractObjectivesTo discuss present knowledge about the relation between adipose tissue, inflammation and the Mediterranean-style diet.DesignReview of the literature and personal perspectives.Setting and resultsRecent studies indicate that adipose tissue is an endocrine organ producing numerous proteins, collectively referred to as adipokines, with broad biological activity, which play an important autocrine role in obesity-associated complications. Adipose tissue in general and visceral fat in particular are thought to be key regulators of inflammation which is heavily involved in the onset and development of atherothrombotic disease. Moreover, chronic inflammation may also represent a triggering factor in the origin of the metabolic syndrome and type 2 diabetes mellitus. An increased release of proinflammatory adipokines from the visceral adipose tissue, associated with a reduced secretion of anti-inflammatory adipokines and cytokines, could determine a low-grade chronic inflammatory state which might play a role in the future development of the metabolic syndrome, diabetes and atherosclerosis through both insulin resistance and endothelial dysfunction. Interventions aimed at decreasing weight loss and improving adherence to a Mediterranean-style diet in people with obesity or metabolic syndrome decrease the inflammatory milieu and ameliorate both insulin resistance and endothelial dysfunction.ConclusionsAppropriate dietary patterns, as those associated with the eating model of Mediterranean-type diets, represent therapeutic strategies to reduce inflammation and the associated metabolic and cardiovascular risk.

Effect of voluntary exercise on peripheral tissue glucocorticoid receptor content and the expression and activity of 11β-HSD1 in the Syrian hamster

2006 ◽  
Vol 100 (5) ◽  
pp. 1483-1488 ◽  
Author(s):  
Agnes E. Coutinho ◽  
Jonathan E. Campbell ◽  
Sergiu Fediuc ◽  
Michael C. Riddell
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Metabolic Syndrome ◽  
Enzyme Activity ◽  
Adipose Tissue ◽  
Protein Expression ◽  
Aerobic Exercise ◽  
Visceral Adipose Tissue ◽  
The Metabolic Syndrome ◽  
Visceral Adipose

Recent findings indicate that elevated levels of glucocorticoids (GC), governed by the expression of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and GC receptors (GR), in visceral adipose tissue and skeletal muscle lead to increased insulin resistance and the metabolic syndrome. Paradoxically, evidence indicates that aerobic exercise attenuates the development of the metabolic syndrome even though it stimulates acute increases in circulating GC levels. To investigate the hypothesis that training alters peripheral GC action to maintain insulin sensitivity, young male hamsters were randomly divided into sedentary (S) and trained (T) groups ( n = 8 in each). The T group had 24-h access to running wheels over 4 wk of study. In muscle, T hamsters had lower 11β-HSD1 protein expression (19.2 ± 1.40 vs. 22.2 ± 0.96 optical density, P < 0.05), similar 11β-HSD1 enzyme activity (0.9 ± 0.27% vs. 1.1 ± 0.26), and lower GR protein expression (9.7 ± 1.86 vs. 15.1 ± 1.78 optical density, P < 0.01) than S hamsters. In liver, 11β-HSD1 protein expression tended to be lower in T compared with S (19.2 ± 0.56 vs. 21.4 ± 1.05, P = 0.07), whereas both enzyme activity and GR protein expression were similar. In contrast, visceral adipose tissue contained ∼2.7-fold higher 11β-HSD1 enzyme activity in T compared with S (12.9 ± 3.3 vs. 4.8 ± 1.5% conversion, P < 0.05) but was considerably smaller in mass (0.24 ± 0.02 vs. 0.71 ± 0.06 g). Thus the intracellular adaptation of GC regulators to exercise is tissue specific, resulting in decreases in GC action in skeletal muscle and increases in GC action in visceral fat. These adaptations may have important implications in explaining the protective effects of aerobic exercise on insulin resistance and other symptoms of the metabolic syndrome.

Adipose tissue inflammation and insulin resistance: all obese humans are not created equal

2010 ◽  
Vol 430 (2) ◽  
pp. e1-e4 ◽  
Author(s):  
Marie-Soleil Gauthier ◽  
Neil B. Ruderman
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Obese Individual ◽  
Low Grade ◽  
Key Factors ◽  
Insulin Resistant ◽  
The Metabolic Syndrome ◽  
Biochemical Journal ◽  
Visceral Adipose ◽  
Low Grade Inflammation

In recent years, it has become widely accepted that obesity is characterized by a chronic low-grade inflammation of adipose tissue that predisposes affected individuals to insulin resistance, Type 2 diabetes and other disorders associated with the metabolic syndrome. On the other hand, a subset of obese individuals appears to be protected against insulin resistance and the disorders to which it predisposes. The comparison between such insulin-sensitive and insulin-resistant obese individuals offers a unique opportunity to identify key factors that either contribute to or prevent the development of insulin resistance in humans, without the confounding effect of a major difference in fat mass. In the previous issue of the Biochemical Journal, Barbarroja et al. reported that insulin-sensitive obese individuals show less inflammation in their visceral adipose tissue than a group of insulin-resistant subjects matched for BMI (body mass index). This finding reinforces the concept that inflammation in adipose tissue may be a cause of insulin resistance in most obese individuals, although it does not prove it. Further studies will be required for this purpose, as well as to identify the pathogenetic factors that determine whether or not adipose tissue of an obese individual becomes inflamed.

scholarly journals NK cells in human visceral adipose tissue contribute to obesity‐associated insulin resistance through low‐grade inflammation

2020 ◽  
Vol 10 (6) ◽  
Author(s):  
Kristiaan Wouters ◽  
Yvo H.A.M. Kusters ◽  
Mitchell Bijnen ◽  
Suzan Wetzels ◽  
Xiaodi Zhang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Nk Cells ◽  
Visceral Adipose Tissue ◽  
Low Grade ◽  
Visceral Adipose ◽  
Low Grade Inflammation

scholarly journals Elevated serum uric acid is a facilitating mechanism for insulin resistance mediated accumulation of visceral adipose tissue

2020 ◽  
Author(s):  
Luisa Fernández-Chirino ◽  
Neftali Eduardo Antonio-Villa ◽  
Arsenio Vargas-Vázquez ◽  
Paloma Almeda-Valdés ◽  
Donají Gómez-Velasco ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Uric Acid ◽  
Serum Uric Acid ◽  
Visceral Adipose Tissue ◽  
Visceral Obesity ◽  
Causal Mechanism ◽  
Mediation Analyses ◽  
Bidirectional Relationship ◽  
Visceral Adipose

BACKGROUND: Serum uric acid (SUA) has a relationship with cardiometabolic conditions such as insulin resistance (IR) and visceral adipose tissue (VAT) accumulation. Here, we aimed to clarify the nature of this relationship and the underlying causality mechanism. METHODS: We conducted a population-based cross-sectional study comprising 8,504 subjects joining both NHANES 2003-2004 and 2011-2012 cycles and ENSANUT Medio Camino 2016. We performed mixed effects linear regression models using HOMA2-IR, adipoIR, and METS-VF as indicators of IR and VAT accumulation. Furthermore, we performed mediation analyses to assess a potential causal mechanism and ROC curves to establish cut-off points for identification of IR and visceral obesity using SUA. Finally, with an additional dataset comprised of 226 subjects with both euglycemic hyperinsulinemic clamp (EHC) and dual X-ray absorptiometry (DXA) measurements for IR and VAT accumulation, we performed a network of confirmatory mediation analyses. RESULTS:We found that SUA has a mediating role inside the bidirectional relationship between IR and visceral obesity, and it is part of an underlying causality mechanism which includes adiponectin. The proportion of the mechanism mediated by SUA is greater when stated that IR (in either peripheral or adipose tissue) leads to VAT accumulation (14.90%[13.20%-17.00%] and 15.54%[13.61% - 18.00%] to 4.88%[3.06%-7.00%] and 8.13%[5.91% - 10.00%]) instead of the opposite direction. This result was confirmed by mediation analyses using gold-standard measurements. CONCLUSIONS:Elevated SUA acts as mediator inside the bidirectional relationship between IR andVAT accumulation. Its role appears to be larger when considering adipose tissue IR as the promoter for VAT accumulation.

scholarly journals Protocatechuic acids protects against high glucose- induced insulin resistance in human visceral adipose tissue

2016 ◽  
Vol 62 (5) ◽  
pp. 45-46
Author(s):  
Paulina Ormazabal ◽  
Beatrice Scazzocchio ◽  
Rosaria Varì ◽  
Annunziata Iacovelli ◽  
Roberta Masella
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Visceral Adipose Tissue ◽  
High Glucose ◽  
Protective Role ◽  
Insulin Sensitizer ◽  
20 Nm ◽  
Visceral Adipose

Adipocytes exposed to high glucose concentrations exhibit impaired insulin signaling. Binding of insulin to its membrane receptor activates insulin metabolic pathway leading to IRS-1 and AKT phosphorylations. The accumulation of visceral adipose tissue (VAT) correlates with insulin resistance and metabolic syndrome. Anthocyanins (ACN) are bioactive food compounds of great nutritional interest. We have shown that protocatechuic acid (PCA), a major metabolite of ACN, might exert insulin-sensitizer activities in human visceral adipose tissue. The aim of this work was to define the protective role of PCA against insulin-resistance induced by high glucose in VAT.Methodology: VAT obtained from control subject (BMI≤25) were separated in four experimental groups: i) PCA: samples treated for 24 h with 100 μM PCA, ii) GLU: VAT treated with 30 mM glucose for 24 h, iii) PCA+GLU: 1 hour incubation with 100 μM PCA before adding glucose (30 mM, 24 h), iv) CTR: vehicle. After treatment, VAT groups were (or not) acutely stimulated with insulin (20 nM, 20 min). Tyr-IRS-1 and Ser-Akt phosphorylations were assessed by Western blotting (WB) in basal or insulin stimulated tissues in all experimental groups. Samples were assessed for IRS-1, IR, Akt and GLUT4 protein content by WB. Results: No differences in protein contents between experimental groups were found. GLU tissues showed a lower increment in insulin-stimulated phosphorylation of IRS-1 and Akt compared to CTR and PCA samples. This impaired activation was completely reversed by the pretreatment with PCA.Conclusion: An in-vitro insulin-resistance condition induced by high glucose was established in biopsies of VAT. PCA restores the ability of GLU-tissues to fully respond to insulin by increasing IRS-1 and Akt phosphorylations. These results confirm the insulin-sensitizer effect of PCA on VAT previously reported by our group. An anthocyanin rich diet might help to protect against insulin-resistance in VAT.

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