Microarray analysis of Adipose tissue of Short-term HFD-fed mice
ABSTRACT: Tissue inflammation is a key factor underlying insulin resistance in established obesity. Several models of immuno-compromised mice are protected from obesity-induced insulin resistance. However, it is unanswered whether inflammation triggers systemic insulin resistance or vice versa in obesity. The purpose of this study was to assess these questions. 8-week-old C57BL/6J male mice was treated with 60% HFD for 0 day (NCD), 3 days, and 7 days. Eipididymal fat was fractionated. Each groups have three replicates.
Project description:Cytokines of the IL-1 family are important modulators of obesity-induced inflammation and the development of systemic insulin resistance. Here, we report that IL-37, a newly-described antiinflammatory member of the IL-1 family, affects obesity-induced inflammation and insulin resistance. IL-37 transgenic mice (IL-37tg) did not develop an obese phenotype in response to a high-fat diet (HFD). Unlike WT mice, IL-37tg mice exhibited reduced numbers of adipose tissue macrophages and preserved glucose tolerance and insulin sensitivity after 16 weeks of HFD. A short-term HFD intervention revealed that the IL-37-mediated improvement in glucose tolerance is independent of bodyweight. IL-37tg mice manifested a beneficial metabolic profile with higher circulating levels of the anti-inflammatory adipokine adiponectin. In vitro treatment of differentiating adipocytes with recombinant IL-37 reduced adipogenesis. The beneficial effects of recombinant IL-37 involved activation of AMPK signaling. In humans, steady-state IL-37 adipose tissue mRNA levels were positively correlated with insulin sensitivity, lower adipose tissue levels of leptin and a lower inflammatory status of the adipose tissue. These findings reveal IL-37 as an important anti-inflammatory modulator during obesity-induced inflammation and insulin resistance in both mice and humans and suggest that IL-37 is a potential target for the treatment of obesity-induced insulin resistance and type 2 diabetes. Gene arrays were performed on epidydimal white adipose tissue samples from wild type and human IL37-overexpressing transgenic mice fed a high fat diet for 16 weeks.
Project description:Natural killer (NK) cells contribute to the development of obesity-associated insulin resistance. We demonstrate that in mice obesity promotes the expansion of interleukin-6 receptor (IL6Ra)-expressing NK cells, which also express a number of other myeloid lineage genes such as the colony-stimulating-factor 1 receptor (Csf1r). Selective ablation of Csf1r- expressing NK cells prevents obesity and insulin resistance. Moreover, conditional inactivation of IL6Ra or Stat3 in NK cells limits obesity-associated formation of myeloid signature NK cells, protects from obesity, insulin resistance and obesity-associated inflammation. Also in humans IL6Ra+ NK cells increase in obesity, correlate with markers of systemic low-grade inflammation and their gene expression profile overlaps with characteristic gene sets of NK cells in obese mice. Collectively, we demonstrate that obesity-associated inflammation and metabolic disturbances depend on IL-6/Stat3-dependent formation of distinct NK cells, which may provide a novel target for the treatment of obesity, metaflammation-associated pathologies and diabetes. Overall design: RNA sequencing of two types of NK cells from mouse and human (IL6Ra negative NK cells vs. IL6Ra positive NK cells) and mouse organs (IL6Ra_NKdel vs. IL6Ra_NKflox)
Project description:Insulin resistance drives the development of type 2 diabetes (T2D). In liver, diacylglycerol (DAG) is a key mediator of lipid-induced insulin resistance. DAG activates protein kinase C epsilon (PKCÎµ), which phosphorylates and inhibits the insulin receptor. In rats, a 3-day high fat diet produces hepatic insulin resistance through this mechanism, and knockdown of hepatic PKCÎµ protects against high fat diet-induced hepatic insulin resistance. Here we employ a systems level approach to uncover additional signaling pathways involved in high fat diet-induced hepatic insulin resistance. We used quantitative phosphoproteomics to map global in vivo changes in hepatic protein phosphorylation in chow-fed, high fat-fed, and high fat-fed with PKCÎµ knockdown rats to distinguish the impact of lipid- and PKCÎµ-induced protein phosphorylation.
Project description:Chronic, low-grade adipose tissue inflammation associated with adipocyte hypertrophy is an important link in the relationship between obesity and insulin resistance. Although ubiquitin ligases are essential regulators of inflammatory processes, the role of these enzymes in metabolically driven adipose tissue inflammation is relatively unexplored. In this study, we found that the ubiquitin ligase Siah2 is a central factor in obesity-related adipose tissue inflammation. When challenged with chronic excess energy intake, Siah2-null mice become obese with enlarged adipocytes, but do not develop obesity-induced insulin resistance. Proinflammatory gene expression is substantially reduced in the Siah2-null epididymal adipose tissue of the obese Siah2KO mice. Overall design: Twelve samples from four groups: WT low fat diet (LFD), WT high fat diet (LFD), Siah2KO LFD, Siah2KO HFD. There are three replicates for each group. For the replicates, equal amounts of RNA from each animal was combined into 3 pools/group for the four groups. The WT LFD, WT HFD and Siah2KO LFD groups each had 10 animals that were combined into 3, 3, or 4 animals/pool. The Siah2KO HFD group had 8 animals that were combined into 3,3, and 2 animals/pool.
Project description:Metabolic disorders including obesity and insulin resistance have their basis in dysregulated lipid metabolism and low-grade inflammation. In a microarray search of unique lipase-related genes whose expressions are associated with obesity, we found that two secreted phospholipase A2s (sPLA2s), PLA2G5 and PLA2G2E, were robustly induced in adipocytes of obese mice. Analyses of Pla2g5-/- and Pla2g2e-/- mice revealed distinct and previously unrecognized roles of these sPLA2s in diet-induced obesity. PLA2G5 hydrolyzed phosphatidylcholine in fat-overladen low-density lipoprotein to release unsaturated fatty acids, which prevented palmitate-induced M1 macrophage polarization. As such, PLA2G5 tipped the immune balance toward an M2 state, thereby counteracting adipose tissue inflammation, insulin resistance, hyperlipidemia and obesiy. PLA2G2E altered minor lipoprotein phospholipids, phosphatidylserine and phosphatidylethanolamine, and moderately facilitated lipid accumulation in adipose tissue and liver. Collectively, the identification of metabolic sPLA2s adds this gene family to a growing list of lipolytic enzymes that act as metabolic coordinators. white adipose tissues of C57BL/6 mice; two-condition experiment–high fat diet or low fat diet feeding for 18 weeks; 2 replicates, respectively
Project description:Obesity is a risk factor for numerous metabolic disorders; however, not all obese individuals are prone to insulin resistance. The central aim of this study was to identify molecular pathways directly related to insulin resistance independent of BMI in obesity. We sought to determine the gene expression signature of adipose tissue in a body mass index (BMI)-matched obese cohort of patients that are either insulin sensitive or insulin resistant. We determined the global gene expression signatures of omental and subcutaneous adipose tissue samples obtained from insulin-sensitive obese and insulin-resistant obese patients undergoing gastric bypass surgery.
Project description:Obesity-associated insulin resistance is characterized by a state of chronic, low-grade inflammation that is associated with the accumulation of M1 proinflammatory macrophages in adipose tissue. Although different evidence explains the mechanisms linking the expansion of adipose tissue and adipose tissue macrophage (ATM) polarization, in the current study we investigated the concept of lipid-induced toxicity as the pathogenic link that could explain the trigger of this response. We addressed this question using isolated ATMs and adipocytes from genetic and diet-induced murine models of obesity. Through transcriptomic and lipidomic analysis, we created a model integrating transcript and lipid species networks simultaneously occurring in adipocytes and ATMs and their reversibility by thiazolidinedione treatment. We show that polarization of ATMs is associated with lipid accumulation and the consequent formation of foam cell–like cells in adipose tissue. Our study reveals that early stages of adipose tissue expansion are characterized by M2-polarized ATMs and that progressive lipid accumulation within ATMs heralds the M1 polarization, a macrophage phenotype associated with severe obesity and insulin resistance. Furthermore, rosiglitazone treatment, which promotes redistribution of lipids toward adipocytes and extends the M2 ATM polarization state, prevents the lipid alterations associated with M1 ATM polarization. Our data indicate that the M1 ATM polarization in obesity might be a macrophage-specific manifestation of a more general lipotoxic pathogenic mechanism. This indicates that strategies to optimize fat deposition and repartitioning toward adipocytes might improve insulin sensitivity by preventing ATM lipotoxicity and M1 polarization. 15 samples; 2 genotypes and 2 time points
Project description:Obesity is a risk factor for numerous metabolic disorders; however, not all obese individuals are prone to insulin resistance. The central aim of this study was to identify molecular pathways directly related to insulin resistance independent of BMI in obesity. We sought to determine the gene expression signature of adipose tissue in a body mass index (BMI)-matched obese cohort of patients that are either insulin sensitive or insulin resistant. We determined the global gene expression signatures of omental and subcutaneous adipose tissue samples obtained from insulin-sensitive obese and insulin-resistant obese patients undergoing gastric bypass surgery. The SQ sample for Insulin Resistant Patient 6 has been removed from the study.
Project description:Inflammation plays a key role in the pathogenesis of obesity. Chronic overfeeding leads to macrophage infiltration in the adipose tissue, resulting in pro-inflammatory cytokine production. Both microbial and endogenous danger signals trigger assembly of the intracellular innate immune sensor Nlrp3 [NLR family, pyrin domain containing 3] resulting in caspase-1 activation and production of pro-inflammatory cytokines interleukin (IL)-1beta and IL-18. Here, we showed that mice deficient in Nlrp3, ASC [apoptosis-associated speck-like protein containing a CARD; a.k.a PYCARD (PYD and CARD domain containing)] and caspase-1 were resistant to the development of high fat diet-induced obesity, which correlated with protection from obesity-induced insulin resistance. Detailed metabolic and molecular phenotyping demonstrated that the inflammasome controls energy expenditure and adipogenic gene expression during chronic overfeeding. These findings reveal a critical function of the inflammasome in obesity and insulin resistance and suggest inhibition of the inflammasome as a potential therapeutic strategy. Keywords: Expression profiling by array Wild-type (WT), ASC-null and Casp1-null mice were subjected to high fat diet feeding for 16 weeks. After the diet intervention period, the animals were killed and epididymal white adipose tissue was removed. Total RNA was isolated and subjected to gene expression profiling.