scholarly journals Insulin resistance and adipose tissue inflammation induced by a high-fat diet are attenuated in the absence of hepcidin

2021 ◽  
Author(s):  
Jithu Varghese James ◽  
Joe Varghese ◽  
Nikhitha Mariya John ◽  
Jean Christophe Deschemin ◽  
Sophie Vaulont ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
High Fat Diet ◽  
Iron Homeostasis ◽  
Wild Type ◽  
High Fat ◽  
Knock Out ◽  
Body Iron ◽  
Iron Stores ◽  
Underlying Basis

Increased body iron stores and inflammation in adipose tissue have been implicated in the pathogenesis of insulin resistance (IR) and type 2 diabetes mellitus. However, the underlying basis of these associations are unclear. In order to assess this, we studied how IR and associated inflammation in adipose tissue developed in the presence of increased body iron stores. Male hepcidin knock-out (Hamp1-/-) mice, which have increased body iron stores, and wild-type (WT) mice were fed a high-fat diet (HFD) for 12 and 24 weeks. Development of IR and metabolic parameters linked to this, insulin signaling in tissue, and inflammation and iron-related parameters in visceral adipose tissue were studied in these animals. HFD-feeding resulted in impaired glucose tolerance in both genotypes of mice. In response to the HFD for 24 weeks, Hamp1-/- mice gained less body weight and developed less IR than corresponding WT mice. This was associated with less lipid accumulation in the liver and decreased inflammation and lipolysis in the adipose tissue in the knock-out mice, than in the WT animals. Fewer macrophages infiltrated the adipose tissue in the knockout mice than in wild-type mice, with these macrophages exhibiting a predominantly anti-inflammatory (M2-like) phenotype. These observations suggest a novel role of hepcidin (central regulator of systemic iron homeostasis) in the development of inflammation in adipose tissue and insulin resistance, in response to a high-fat diet.

SO023HEPATOCYTE GROWTH FACTOR (HGF) PRECLUDE HIGH-FAT DIET-INDUCED OBESITY AND IMPROVED INSULIN RESISTANCE IN MICE

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Jun Muratsu ◽  
Yoshiaki Taniyama ◽  
Fumihiro Sanada ◽  
Atsuyuki Morishima ◽  
Katsuhiko Sakaguchi ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Body Weight ◽  
Adipose Tissue ◽  
Growth Factor ◽  
Inflammatory Mediators ◽  
High Fat Diet ◽  
Neutralizing Antibody ◽  
Mrna Levels ◽  
Wild Type ◽  
High Fat

Abstract Background and Aims Obesity and its associated chronic inflammation in adipose tissue initiate insulin resistance, which is related to several pathologies including hypertension and atherosclerosis. Previous reports demonstrated that circulating hepatocyte growth factor (HGF) level was associated with obesity and type 2 diabetes. However, its precise role in obesity and related-pathology is unclear. Method In this experiment, cardiac-specific over-expression of human HGF in mice (HGF-Tg mice) which showed 4-5 times higher serum HGF levels than wild-type mice were used. We chose cardiac specific HGF overexpression, as other strain of HGF transgenic mice such as liver and kidney specific HGF overexpression mice develop cancer and cystic diseases, which are rare in the heart. In the present study, using HGF-Tg mice and anti-HGF neutralizing antibody (HGF-Ab), we explored the role of HGF in obese and insulin resistance induced by high fat diet (HFD) for 14 weeks (200 or 400ug/week). Results With normal chow diet (ND), there were no significant changes in body weight between WT and HGF-Tg mice. While body weight in wild-type mice fed with HFD for 14 weeks was significantly increased accompanied with insulin resistance, HGF-Tg mice prevented body weight gain and insulin resistance. Insulin resistance in obesity arises from the combination of altered functions of insulin target cells (e.g., liver, skeletal muscle, and adipose tissue) and the accumulation of macrophages that secrete pro-inflammatory mediators in adipose tissue. The accumulation of macrophages and elevated levels of inflammatory mediators in adipose tissue were significantly inhibited in HGF-Tg mice as compared to wild-type mice. In the gWAT, the mRNA levels of the mature macrophage marker F4/80, the chemoattractants, MCP-1 and CXCL2, and the inflammatory cytokines, such as TNF-α and iNOS, were significantly increased in WT mice fed with HFD. However, these levels were markedly reduced in HGF-Tg mice fed with HFD. Additionally, activation of Akt by insulin administration was significantly reduced in the gWAT SM, and liver by HFD; however, this activation was restored in HGF-Tg mice. Moreover, insulin-induced Akt signaling was decreased in HGF-Ab groups as compared to saline group under HFD condition. Importantly, HFD significantly increased the level of HGF mRNA by approximately 2 fold in gWAT, SM, and liver without changing cMet expression. All together, these data indicate that the HGF as one of the systemic gWAT, SM, and liver-derived growth factor plays a role in compensatory mechanism against insulin-resistance through the at least anti-inflammatory effect in adipose tissue. The HFD-induced obesity in wild-type mice treated with HGF-neutralizing antibody showed an exacerbated response to the glucose tolerance test. Conclusion HGF suppresses inflammation in adipose tissue induced by a high-fat diet, and as a result improves systemic insulin resistance. These gain-of-function and loss-of-function studies demonstrated that the elevated HGF level induced by HFD have protective role against obesity and insulin resistance.

scholarly journals Role of Muscle c-Jun NH2-Terminal Kinase 1 in Obesity-Induced Insulin Resistance

2009 ◽  
Vol 30 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Guadalupe Sabio ◽  
Norman J. Kennedy ◽  
Julie Cavanagh-Kyros ◽  
Dae Young Jung ◽  
Hwi Jin Ko ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
High Fat Diet ◽  
Wild Type ◽  
High Fat ◽  
Akt Activation ◽  
Peripheral Insulin Resistance ◽  
Diet Induced Obesity

ABSTRACT Obesity caused by feeding of a high-fat diet (HFD) is associated with an increased activation of c-Jun NH2-terminal kinase 1 (JNK1). Activated JNK1 is implicated in the mechanism of obesity-induced insulin resistance and the development of metabolic syndrome and type 2 diabetes. Significantly, Jnk1 − / − mice are protected against HFD-induced obesity and insulin resistance. Here we show that an ablation of the Jnk1 gene in skeletal muscle does not influence HFD-induced obesity. However, muscle-specific JNK1-deficient (MKO) mice exhibit improved insulin sensitivity compared with control wild-type (MWT) mice. Thus, insulin-stimulated AKT activation is suppressed in muscle, liver, and adipose tissue of HFD-fed MWT mice but is suppressed only in the liver and adipose tissue of MKO mice. These data demonstrate that JNK1 in muscle contributes to peripheral insulin resistance in response to diet-induced obesity.

Haploinsufficiency of the retinoblastoma protein gene reduces diet-induced obesity, insulin resistance, and hepatosteatosis in mice

2009 ◽  
Vol 297 (1) ◽  
pp. E184-E193 ◽  
Author(s):  
Josep Mercader ◽  
Joan Ribot ◽  
Incoronata Murano ◽  
Søren Feddersen ◽  
Saverio Cinti ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Body Weight ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
High Fat Diet ◽  
Retinoblastoma Protein ◽  
Brown Adipocyte ◽  
Wild Type ◽  
High Fat ◽  
Brown Adipose

Brown adipose tissue activity dissipates energy as heat, and there is evidence that lack of the retinoblastoma protein (pRb) may favor the development of the brown adipocyte phenotype in adipose cells. In this work we assessed the impact of germ line haploinsufficiency of the pRb gene (Rb) on the response to high-fat diet feeding in mice. Rb+/− mice had body weight and adiposity indistinguishable from that of wild-type (Rb+/+) littermates when maintained on a standard diet, yet they gained less body weight and body fat after long-term high-fat diet feeding coupled with reduced feed efficiency and increased rectal temperature. Rb haploinsufficiency ameliorated insulin resistance and hepatosteatosis after high-fat diet in male mice, in which these disturbances were more marked than in females. Compared with wild-type littermates, Rb+/− mice fed a high-fat diet displayed higher expression of peroxisome proliferator-activated receptor (PPAR)γ as well as of genes involved in mitochondrial function, cAMP sensitivity, brown adipocyte determination, and tissue vascularization in white adipose tissue depots. Furthermore, Rb+/− mice exhibited signs of enhanced activation of brown adipose tissue and higher expression levels of PPARα in liver and of PPARδ in skeletal muscle, suggestive of an increased capability for fatty acid oxidation in these tissues. These findings support a role for pRb in modulating whole body energy metabolism and the plasticity of the adipose tissues in vivo and constitute first evidence that partial deficiency in the Rb gene protects against the development of obesity and associated metabolic disturbances.

scholarly journals Adipose Tissue-Specific Deletion of 12/15-Lipoxygenase Protects Mice from the Consequences of a High-Fat Diet

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Banumathi K. Cole ◽  
Margaret A. Morris ◽  
Wojciech J. Grzesik ◽  
Kendall A. Leone ◽  
Jerry L. Nadler
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Adipose Tissue ◽  
Pancreatic Islets ◽  
High Fat Diet ◽  
Epididymal Adipose Tissue ◽  
Wild Type ◽  
High Fat ◽  
Specific Deletion

Type 2 diabetes is associated with obesity, insulin resistance, and inflammation in adipose tissue. 12/15-Lipoxygenase (12/15-LO) generates proinflammatory lipid mediators, which induce inflammation in adipose tissue. Therefore we investigated the role of 12/15-LO activity in mouse white adipose tissue in promoting obesity-induced local and systemic inflammatory consequences. We generated a mouse model for fat-specific deletion of 12/15-LO,aP2-Cre;12/15-LOloxP/loxP, which we call ad-12/15-LO mice, and placed wild-type controls and ad-12/15-LO mice on a high-fat diet for 16 weeks and examined obesity-induced inflammation and insulin resistance. High-fat diet-fed ad-12/15-LO exhibited improved fasting glucose levels and glucose metabolism, and epididymal adipose tissue from these mice exhibited reduced inflammation and macrophage infiltration compared to wild-type mice. Furthermore, fat-specific deletion of 12/15-LO led to decreased peripheral pancreatic islet inflammation with enlarged pancreatic islets when mice were fed the high-fat diet compared to wild-type mice. These results suggest an interesting crosstalk between 12/15-LO expression in adipose tissue and inflammation in pancreatic islets. Therefore, deletion of 12/15-LO in adipose tissue can offer local and systemic protection from obesity-induced consequences, and blocking 12/15-LO activity in adipose tissue may be a novel therapeutic target in the treatment of type 2 diabetes.

scholarly journals 12/15-Lipoxygenase signaling in the endoplasmic reticulum stress response

2012 ◽  
Vol 302 (6) ◽  
pp. E654-E665 ◽  
Author(s):  
Banumathi K. Cole ◽  
Norine S. Kuhn ◽  
Shamina M. Green-Mitchell ◽  
Kendall A. Leone ◽  
Rebekah M. Raab ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Er Stress ◽  
Pancreatic Islets ◽  
High Fat Diet ◽  
Wild Type ◽  
High Fat ◽  
Stress Markers ◽  
Deficient Mice

Central obesity is associated with chronic inflammation, insulin resistance, β-cell dysfunction, and endoplasmic reticulum (ER) stress. The 12/15-lipoxygenase enzyme (12/15-LO) promotes inflammation and insulin resistance in adipose and peripheral tissues. Given that obesity is associated with ER stress and 12/15-LO is expressed in adipose tissue, we determined whether 12/15-LO could mediate ER stress signals. Addition of 12/15-LO lipid products 12(S)-HETE and 12(S)-HPETE to differentiated 3T3-L1 adipocytes induced expression and activation of ER stress markers, including BiP, XBP-1, p-PERK, and p-IRE1α. The ER stress inducer, tunicamycin, upregulated ER stress markers in adipocytes with concomitant 12/15-LO activation. Addition of a 12/15-LO inhibitor, CDC, to tunicamycin-treated adipocytes attenuated the ER stress response. Furthermore, 12/15-LO-deficient adipocytes exhibited significantly decreased tunicamycin-induced ER stress. 12/15-LO action involves upregulation of interleukin-12 (IL-12) expression. Tunicamycin significantly upregulated IL-12p40 expression in adipocytes, and IL-12 addition increased ER stress gene expression; conversely, LSF, an IL-12 signaling inhibitor, and an IL-12p40-neutralizing antibody attenuated tunicamycin-induced ER stress. Isolated adipocytes and liver from 12/15-LO-deficient mice fed a high-fat diet revealed a decrease in spliced XBP-1 expression compared with wild-type C57BL/6 mice on a high-fat diet. Furthermore, pancreatic islets from 12/15-LO-deficient mice showed reduced high-fat diet-induced ER stress genes compared with wild-type mice. These data suggest that 12/15-LO activity participates in ER stress in adipocytes, pancreatic islets, and liver. Therefore, reduction of 12/15-LO activity or expression could provide a new therapeutic target to reduce ER stress and downstream inflammation linked to obesity.

scholarly journals Estrogens Protect against High-Fat Diet-Induced Insulin Resistance and Glucose Intolerance in Mice

Endocrinology ◽  
2009 ◽  
Vol 150 (5) ◽  
pp. 2109-2117 ◽  
Author(s):  
Elodie Riant ◽  
Aurélie Waget ◽  
Haude Cogo ◽  
Jean-François Arnal ◽  
Rémy Burcelin ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Glucose Intolerance ◽  
High Fat Diet ◽  
Chow Diet ◽  
High Fat ◽  
Normal Chow ◽  
Visceral Adipose ◽  
Deficient Mice ◽  
Normal Chow Diet

Although corroborating data indicate that estrogens influence glucose metabolism through the activation of the estrogen receptor α (ERα), it has not been established whether this pathway could represent an effective therapeutic target to fight against metabolic disturbances induced by a high-fat diet (HFD). To this end, we first evaluated the influence of chronic 17β-estradiol (E2) administration in wild-type ovariectomized mice submitted to either a normal chow diet or a HFD. Whereas only a modest effect was observed in normal chow diet-fed mice, E2 administration exerted a protective effect against HFD-induced glucose intolerance, and this beneficial action was abolished in ERα-deficient mice. Furthermore, E2 treatment reduced HFD-induced insulin resistance by 50% during hyperinsulinemic euglycemic clamp studies and improved insulin signaling (Akt phosphorylation) in insulin-stimulated skeletal muscles. Unexpectedly, we found that E2 treatment enhanced cytokine (IL-6, TNF-α) and plasminogen activator inhibitor-1 mRNA expression induced by HFD in the liver and visceral adipose tissue. Interestingly, although the proinflammatory effect of E2 was abolished in visceral adipose tissue from chimeric mice grafted with bone marrow cells from ERα-deficient mice, the beneficial effect of the hormone on glucose tolerance was not altered, suggesting that the metabolic and inflammatory effects of estrogens can be dissociated. Eventually comparison of sham-operated with ovariectomized HFD-fed mice demonstrated that endogenous estrogens levels are sufficient to exert a full protective effect against insulin resistance and glucose intolerance. In conclusion, the regulation of the ERα pathway could represent an effective strategy to reduce the impact of high-fat diet-induced type 2 diabetes.

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