Luteolin attenuates lipid dysregulation and insulin resistance thorough interplay of liver and adipose tissue in diet-induced obese mice
ABSTRACT: Analysis of effect of luteolin on lipid metabolism at gene expression level. The hypothesis tested in the present study was that luteolin treatment with obesogenic diet suppressed the hepatic lipogenesis pathways. Conversely, in adipose tissue, luteolin stimulated the lipogenesis pathway and it also simultaneously increased the expression of genes controlling lipolysis and TCA cycle. Results provide important information about the effect on diet-induced obesity and its metabolic complications. Total RNA of liver and adipose tissues was obtained from normal diet, high-fat diet and luteolin added high-fat diet-fed mice and mRNA expression-associated with lipid metabolism was measured.
Project description:We identified differentially expressed genes in epididymal white adipose tissue of high fat diet(HFD)-fed mice compared to low fat diet-fed mice using microarray analysis. Microarray analysis revealed that genes related to lipolysis, fatty acid metabolism, mitochondrial energy transduction, oxidation-reduction, insulin sensitivity, and skeletal system development were downregulated in HFD-fed mice, and genes associated with extracellular matrix (ECM) components, ECM remodeling, and inflammation were upregulated. The top 10 up- or downregulated genes include Acsm3, mt-Nd6, Fam13a, Cyp2e1, Rgs1, and Gpnmb, whose roles in obesity-associated adipose tissue deterioration are poorly understood. Total RNA of epididymal white adipose tissue was obtained from low fat diet (10 kcal% fat)- and high fat diet(45 kcal% fat)-fed mice and mRNA expression was measured using microarray analysis.
Project description:Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell–deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue–resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue–resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance. four samples
Project description:Genome-scale analysis of the genetic factors that govern the development of white and brown adipose tissue is still far from complete. In order to identify the key genes that regulate the development of white and brown adipose tissue in mice, the transcriptome analysis was performed on adipose tissues Total RNA obtained from interscapular brown adipose tissue of C57BL/6J mice fed normal diet or high fat diet for 2, 4, 8, 20 and 24 weeks
Project description:We demonstrated that RORa-deficient staggerer mice (RORasg/sg) fed with a high fat diet (HFD) showed reduced adiposity and hepatic triglyceride levels compared to wild type (WT) littermates and were resistant to the development of hepatic steatosis, adipose-associated inflammation, and insulin resistance. Gene expression profiling showed that many genes involved in triglyceride synthesis and storage, including Cidec, Cidea, and Mogat1, were expressed at much lower levels in liver of RORasg/sg mice. In addition to reduced lipid accumulation, inflammation was greatly diminished in white adipose tissue (WAT) of RORasg/sg mice fed with a HFD. The infiltration of macrophages and the expression of many immune-response and pro-inflammatory genes, including those encoding various chemo/cytokines, toll-like receptors, and TNF signaling proteins, were significantly reduced in RORasg/sg WAT. Moreover, RORasg/sg mice fed with a HFD were protected from the development of insulin resistance. Together, these results indicate that RORa plays a critical role in the regulation of several aspects of metabolic syndrome. Therefore, RORa may provide a novel therapeutic target in the management of obesity and associated metabolic diseases. Liver and white adipose tissue (WAT) total RNAs were purified from 5 WT and 5 RORasg/sg (natural deletion of RORa gene in mice) mice fed with a high fat diet for 6 weeks. Then samples were applied on Agilent mouse genome chip.
Project description:Systemic acute inflammatory signals can cause profound anorexia by disrupting the physiological appetite regulation in the hypothalamic milieu. Conversely, obesity related chronic inflammation of the hypothalamus can disturb anorexigenic signals and promote abnormal body weight control. The aim of the present study was to compare the global hypothalamic endophenotype in C57/Bl6 mice exposed to a high-fat diet or with acute illness mediated by LPS. Ten-week old male C57/Bl6 mice (n=18) were randomly divided into four groups; the control 1 group (n =3) was fed a normal diet whereas the high-fat diet (HFD) group (n =6) was fed a high-fat diet for eight weeks. The control 2 group (n=3) received an intraperitoneal injection of saline whereas the LPS group (n=6) received an intraperitoneal injection of LPS. Mice were sacrificed 18-hr post-injection. Both control 2 and LPS groups were fed a normal diet for eight weeks before the injection. The hypothalamic regions were removed and analysed using a 2D LC-MS methodology. The proteomic analysis profiled 9,235 proteins (q<0.05) across all biological states, of which 522 proteins were found modulated in the HFD group and another 579 in the LPS group. The proteomic profiles demonstrated that the systemic acute inflammation linked with anorexia induced a negative feedback loop of appetite control in the hypothalamus, suggesting an effort to re-establish homeostasis. By contrast, the chronic inflammation associated with obesity initiated a “perpetual cycle” of positive feedback enhancement of appetite regulation further exacerbating positive energy balance.
Project description:Time-course analysis of adipocyte gene expression profiles response to high fat diet. The hypothesis tested in the present study was that in diet-induced obesity, early activation of TLR-mediated inflammatory signaling cascades by CD antigen genes, leads to increased expression of pro-inflammatory cytokines and chemokines, resulting in chronic low-grade inflammation. Early changes in collagen genes may trigger the accumulation of ECM components, promoting fibrosis in the later stages of diet-induced obesity. New therapeutic approaches targeting visceral adipose tissue genes altered early by HFD feeding may help ameliorate the deleterious effects of a diet-induced obesity. Total RNA obtained from isolated epididymal and mesenteric adipose tissue of C57BL/6J mice fed normal diet or high fat diet for 2, 4, 8, 20 and 24weeks
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:Mice were fed for 6 months with a normal chow (NC) or a high fat diet (HFD). After 6 months of diet, high fat fed mice with Low, Medium and High body weight, but with similar glucose intolerance, were selected. These selected mice as well as NC mice were then treated with Rimonabant or Vehicle for 1 month. After treatment, mice were sacrificed and visceral and subcutaneous adipose tissues were collected and immediately frozen in liquid nitrogen. Total RNA from each sample was further extracted, purified, quality-controled before and after amplification, Cy5-labeled and co-hybridized with a Cy3-labeled mouse Universal Reference total RNA on the mouse 17K microarray. Keywords: diet response, pharmacological response Each individual RNA sample was hybridized with a mouse Universal Reference Total RNA
Project description:Diet-induced obesity is reported to induce a phenotypic switch in adipose tissue macrophages from an antiinflammatory M2 state to a proinflammatory M1 state. Telmisartan, an angiotensin II type 1 receptor antagonist and a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist, reportedly has beneficial effects on insulin sensitivity. We studied the effects of telmisartan on the adipose tissue macrophage phenotype in high fat-fed mice. Telmisartan was administered for 5 weeks to high fat-fed C57BL/6 mice. Insulin sensitivity, macrophage infiltration, and the gene expressions of M1 and M2 markers in epididymal fat tissues were examined. Insulin- or a glucose-tolerance test showed that telmisartan treatment improved insulin resistance, decreasing the body weight gain, visceral fat weight and adipocyte size without affecting the amount of food intake. Telmisartan treatment reduced the number of CD11c-positive cells and crown-like structures. Telmisartan reduced the mRNA expressions of M1 macrophage markers, such as TNF-alpha and IL-6, and increased the expression of M2 markers, such as IL-10 and Mgl2. The reduction of M1 macrophage markers, as well as the increased gene expression of M2 markers especially IL-10, is a possible mechanism for the improvement of insulin sensitivity by telmisartan. Six-week-old male C57BL/6J mice were purchased from CLEA Japan. The mice were fed a chow that contained 10% of its calories from fat (control) or a high-fat diet (HFD) that contained 30% of its calories from fat for 24 weeks. The high fat-fed mice were randomized to 3 groups. Either telmisartan (~3 mg/kg/day) in drinking water (HFD+Tel), candesartan (~3 mg/kg/day) in drinking water (HFD+Can), or a HFD without any drugs (HFD) was administered for the next 5 weeks. Two mice were treated per group. Epididymal adipose tissues were rapidly removed from each mouse. Gene expression in epididymal fat tissue was analyzed using a GeneChip® system with the Mouse Genome 430 2.0 Array, which was spotted with 45,101 probe sets (Affymetrix, Santa Clara, CA, USA). Sample preparation for the array hybridization was performed according to the manufacturer’s instructions. In short, 5 μg of total RNA was used to synthesize double-stranded cDNA using the GeneChip® Expression 3′-Amplification Reagents One-Cycle cDNA Synthesis Kit (Affymetrix). Biotin-labeled cRNA was then synthesized from the cDNA using GeneChip® Expression 3′-Amplification Reagents for IVT Labeling (Affymetrix). After fragmentation, the biotinylated cRNA was hybridized to arrays at 45 °C for 16 h. The arrays were washed, stained with streptavidin-phycoerythrin, and scanned using a probe array scanner. The scanned chip was analyzed using the GeneChip Analysis Suite software (Affymetrix). Hybridization intensity data were converted into a presence/absence call for each gene, and changes in gene expression between experiments were detected by a comparison analysis. Data was shown as the fold change relative to the expression level of normal chow-fed mice.