Abstract 74: The Nox4 Inhibitor GKT137831, Prevents Aldosterone Production by Adipocytes and Protects Against Adipose Tissue Inflammation and Fibrosis in Obese Mice

Aldosterone (aldo) plays an important role in obesity-associated cardiovascular risk. We demonstrated that aldo is produced by adipocytes, an effect associated with increased generation of reactive oxygen species (ROS). These processes are exaggerated in obesity. The relationship between adipocyte aldosterone and ROS is unclear. We postulated that Nox4-derived ROS is important for aldo production in adipocytes and leads to a pro-inflammatory phenotype in obesity. Studies were performed in db/m (lean) and db/db (obese) mice, treated with low (20mg/kg/day) or high dose (60mg/kg/day) GKT137831 (GKT, Nox4 inhibitor, 16 weeks). Epididymal (EVAT) and perivascular (PVAT) fat were collected. Plasma and adipocyte aldo were measured by ELISA. Adipose tissue fibrosis was evaluated by picro Sirius red staining and inflammatory mediators by immunostudies. Body weight was increased in db/db mice (61.8g vs control 33.5g), with no effect of GKT. Epididymal adiposity was increased in db/db mice (0.098g vs. 0.067g, p<0.05). Plasma aldo levels in db/db (pg/mL: 518 vs. 272g) and aldo levels in culture media from db/db adipocytes were increased (pg/mL/μg RNA: 1964 vs. 388), p<0.05. All effects decreased by high dose GKT. In PVAT, CYP11B2 gene expression was increased in db/db (2.6±0.8 vs control 1.1±0.1, p<0.05), an effect blocked by Nox4 inhibition. Gene expression of adipocyte differentiation marker, AP2, was increased (3.5±1.1 vs control 1.4±0.4) while anti-inflammatory marker adiponectin was decreased (0.7±0.1 vs control 1.3±0.2, p<0.05)) in obese mice. GKT decreased AP2 levels. Adipocyte-derived TNFα was increased in db/db (4.9±1.8 vs control 1.6±0.6, p<0.05), an effect blocked by GKT. Pro-collagen I, marker of fibrosis, was increased in db/db mice (132±11 vs control 87±4, p<0.05). Sirius red staining was exaggerated in EVAT from db/db mice, and decreased by Nox4 inhibition. In conclusion, Nox4 plays a role in regulating adipocyte-derived aldosterone and promotes a pro-inflammatory and profibrotic adipose phenotype in obese db/db mice. These findings suggest that adipocyte Nox4 links hyperaldosteronism and inflammation/fibrosis in adiposity and as such may be a putative therapeutic target for obesity-associated cardiovascular damage.

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Abstract 010: Adipocyte-derived Aldosterone And Cortisol Are Nox1/4 Dependent: Implications In Obesity-associated Vascular Dysfunction.

Hypertension ◽

10.1161/hyp.64.suppl_1.010 ◽

2014 ◽

Vol 64 (suppl_1) ◽

Author(s):

Sarah E Even ◽

Francisco J Rios ◽

Aurélie Nguyen Dinh Cat ◽

Tayze T Antunes ◽

Marie Briet ◽

...

Keyword(s):

Gene Expression ◽

Vascular Function ◽

Culture Media ◽

Vascular Dysfunction ◽

Ros Generation ◽

High Dose ◽

H2o2 Production ◽

Ang Ii ◽

Obese Mice ◽

Human Adipocytes

We previously demonstrated that aldosterone (aldo) is produced by adipocytes, an effect associated with reactive oxygen species (ROS) production and adipokine production, which influences vascular function. These processes are exaggerated in obesity. Whether ROS themselves play a role in adipocyte-derived aldo is unclear. Studies were performed in db/m (lean) and db/db (obese) mice, treated with low (20mg/kg/day) or high dose (60mg/kg/day) GKT137831 (GKT, Nox1/4 inhibitor, 16 weeks). Epididymal (EVAT) and perivascular (PVAT) fat were collected. Human adipocytes (SW872) were also studied. Aldo and corticosterone levels were measured by ELISA. Gene expression was assessed by qPCR. ROS generation was assessed by chemiluminescence and amplex red. Plasma aldo levels in db/db (pg/mL: 518 vs. 272g) and aldo levels in culture media from db/db adipocytes were increased (pg/mL/μg RNA: 1964 vs. 388), p<0.05. All effects were decreased by high dose GKT. In PVAT, CYP11B2 gene expression was increased in db/db (2.6±0.8 vs control 1.1±0.1, p<0.05), an effect blocked by Nox1/4 inhibition. Corticosterone levels in culture media from db/db adipocytes were also increased. Gene expression of adipocyte differentiation marker, AP2, was increased (3.5±1.1 vs control 1.4±0.4) in obese mice. GKT decreased AP2 levels. In human adipocytes, AngII stimulation increased aldo (6 fold) and cortisol (4 fold) production, as well as superoxide (1 fold) and H2O2 (2 fold) levels (p<0.05 vs vehicle). Increased levels of superoxide by Ang II were blocked by GKT and ML171 (Nox1 inhibitor); while Ang II-induced H2O2 production was inhibited only by GKT. Ang II-induced aldo production was blocked by tempol (SOD mimetic), GKT and ML171. In contrast, cortisol was only blocked by tempol and GKT. In conclusion, aldo production in adipocytes is dependent on ROS formation and involves Nox1 and Nox4. Nox4 also influences adipocyte-derived cortisol. These data suggest that Nox1/4 may play a role in adipocyte-derived aldosterone and cortisol production, effects that are amplified in obesity. Our findings suggest that adipocyte Nox1/4 may be a putative therapeutic target in obesity-associated hyperaldosteronism and cardiovascular damage.

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Study of the Alteration of Gene Expression in Adipose Tissue of Diet-Induced Obese Mice by Microarray and Reverse Transcription-Polymerase Chain Reaction Analyses

Endocrinology ◽

10.1210/en.2003-0456 ◽

2003 ◽

Vol 144 (11) ◽

pp. 4773-4782 ◽

Cited By ~ 105

Author(s):

R. C. Moraes ◽

A. Blondet ◽

K. Birkenkamp-Demtroeder ◽

J. Tirard ◽

T. F. Orntoft ◽

...

Keyword(s):

Gene Expression ◽

Polymerase Chain Reaction ◽

Adipose Tissue ◽

Reverse Transcription ◽

Obese Mice ◽

Chain Reaction ◽

Polymerase Chain

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Effect of acute cold exposure on uncoupling protein gene expression in brown adipose tissue of monosodium-L-glutamate-induced obese mice.

The Japanese Journal of Pharmacology ◽

10.1016/s0021-5198(19)51450-0 ◽

1993 ◽

Vol 61 ◽

pp. 137

Author(s):

Fujiko Tsukahara ◽

Yoko Uchida ◽

Teruko Nomoto ◽

Takamura Muraki

Keyword(s):

Gene Expression ◽

Adipose Tissue ◽

Brown Adipose Tissue ◽

Cold Exposure ◽

Protein Gene ◽

Uncoupling Protein ◽

Obese Mice ◽

Acute Cold Exposure ◽

Brown Adipose ◽

Uncoupling Protein Gene

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Peripancreatic adipose tissue protects against high-fat-diet-induced hepatic steatosis and insulin resistance in mice

International Journal of Obesity ◽

10.1038/s41366-020-00657-6 ◽

2020 ◽

Vol 44 (11) ◽

pp. 2323-2334

Author(s):

Belén Chanclón ◽

Yanling Wu ◽

Milica Vujičić ◽

Marco Bauzá-Thorbrügge ◽

Elin Banke ◽

...

Keyword(s):

Gene Expression ◽

Insulin Resistance ◽

Adipose Tissue ◽

Hepatic Steatosis ◽

High Fat Diet ◽

Obese Mice ◽

High Fat ◽

Insulin Levels ◽

Fat Depots ◽

Fat Depot

Abstract Background/objectives Visceral adiposity is associated with increased diabetes risk, while expansion of subcutaneous adipose tissue may be protective. However, the visceral compartment contains different fat depots. Peripancreatic adipose tissue (PAT) is an understudied visceral fat depot. Here, we aimed to define PAT functionality in lean and high-fat-diet (HFD)-induced obese mice. Subjects/methods Four adipose tissue depots (inguinal, mesenteric, gonadal, and peripancreatic adipose tissue) from chow- and HFD-fed male mice were compared with respect to adipocyte size (n = 4–5/group), cellular composition (FACS analysis, n = 5–6/group), lipogenesis and lipolysis (n = 3/group), and gene expression (n = 6–10/group). Radioactive tracers were used to compare lipid and glucose metabolism between these four fat depots in vivo (n = 5–11/group). To determine the role of PAT in obesity-associated metabolic disturbances, PAT was surgically removed prior to challenging the mice with HFD. PAT-ectomized mice were compared to sham controls with respect to glucose tolerance, basal and glucose-stimulated insulin levels, hepatic and pancreatic steatosis, and gene expression (n = 8–10/group). Results We found that PAT is a tiny fat depot (~0.2% of the total fat mass) containing relatively small adipocytes and many “non-adipocytes” such as leukocytes and fibroblasts. PAT was distinguished from the other fat depots by increased glucose uptake and increased fatty acid oxidation in both lean and obese mice. Moreover, PAT was the only fat depot where the tissue weight correlated positively with liver weight in obese mice (R = 0.65; p = 0.009). Surgical removal of PAT followed by 16-week HFD feeding was associated with aggravated hepatic steatosis (p = 0.008) and higher basal (p < 0.05) and glucose-stimulated insulin levels (p < 0.01). PAT removal also led to enlarged pancreatic islets and increased pancreatic expression of markers of glucose-stimulated insulin secretion and islet development (p < 0.05). Conclusions PAT is a small metabolically highly active fat depot that plays a previously unrecognized role in the pathogenesis of hepatic steatosis and insulin resistance in advanced obesity.

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Original Article. Inflammatory effect of 2-aminoanthracene (2AA) on adipose tissue gene expression in pregnant Sprague Dawley rats

Interdisciplinary Toxicology ◽

10.1515/intox-2016-0003 ◽

2016 ◽

Vol 9 (1) ◽

pp. 17-24

Author(s):

Shamaya L. Whitby ◽

Daniel A. Hunter ◽

Wilson Yau ◽

Elizabeth W. Howerth ◽

Worlanyo E. Gato

Keyword(s):

Gene Expression ◽

Adipose Tissue ◽

Dose Group ◽

Low Dose ◽

Mononuclear Cells ◽

Postnatal Period ◽

High Dose ◽

Sprague Dawley ◽

Polycyclic Aromatic ◽

Altered Gene

Abstract Adipocyte dysfunction may be a critical link between obesity and insulin resistance as a result of abnormal fat storage and mobilization. Adipocytes uniquely secrete adipokines and cytokines, such as leptin and TNFα, wich promote insulin sensitivity. Previously we reported insulin-signaling related altered gene expression in animals exposed to 2-Aminoanthracene (2AA). 2AA is an aminosubstituted polycyclic aromatic hydrocarbon used in manufacturing dyes, chemicals, inks, resins, and polyurethanes. The objective of this study was to examine the inflammation related effects of 2AA exposure from gestation to postnatal period on dams that ingested 2AA. To examine 2AA effects, pregnant dams were assigned into dose regimens of 2AA. Dams were fed 2AA contaminated diet during the period of gestation and postpartum. The expression of key gene transcripts reported to be important in mediating inflammatory processes was examined via quantitative RT-PCR. Histologic examination of adipose tissue (AT) was also carried out to understand the anatomy of AT due to 2AA exposure during gestation and two weeks postpartum. Examination of the adipose tissue for microscopic changes revealed no alterations between control and low-dose animals. However, AT of the high-dose animals was infiltrated by increased numbers of CD68+mononuclear cells (macrophages) and small numbers of eosinophils and mast cells, consistent with inflammation. In addition, analysis of the mRNA expression of cytokines and adipokines demonstrated the importance of inflammation in AT dysfunction. For instance, TNFα, LEPTIN and IL-6 transcripts were relatively more expressed in the low dose animals than in the high dose and control rats. At the protein level, however, high amounts of cytokines were noted. The effects of 2AA on pregnant dams appear to be more pronounced in the high dose group than in the low dose group, possibly indicating increased susceptibility of rat offspring within this group to elicit a diabetic-type response.

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