Stimulation with Peptidoglycan induces interleukin 6 and TLR2 expression and a concomitant downregulation of expression of adiponectin receptors 1 and 2 in 3T3-L1 adipocytes

<p>Abstract</p> <p>Background</p> <p>Inflammation is a major component of obesity and diabetes, and toll-like receptors (TLRs) play critical roles in the regulation of inflammation and response to pathogen associated molecular patterns (PAMPs) and fatty acids in. Although immune cells such as macrophages are primarily responsible for recognition and clearance of pathogens, adipocytes are also closely involved in the regulation of innate immunity and inflammation. Whereas it has been demonstrated that adipocytes respond to TLR4 stimulation with lipopolysacccharide, very little is known about their response to the TLR2 agonist, peptidoglycan.</p> <p>Methods</p> <p>We investigated the response to peptidoglycan from <it>Staphylococcus aureus </it>in differentiated 3T3-L1 adipocytes. Real-time PCR analysis was used to quantify the expression of interleukin 6 (IL6), adiponectin receptors (adipoR1 and adipoR2), toll-like receptor 2 (TLR2) and 4 (TLR2 4). Media level of IL6 was determined with ELISA.</p> <p>Results</p> <p>Adipocyte stimulation peptidoglycan induces IL6 expression (P < 0.01). Both siRNA mediated suppression of TLR2 and immunoneutralization of TLR2 with a TLR2 specific antibody inhibited response to peptidoglycan (P < 0.05). We also examined the regulation of TLR2 and TLR4 mRNA in peptidoglycan treated cells. Both peptidoglycan and lipopolysaccharide (LPS) robustly induce TLR2 mRNA expression, whereas TLR4 mRNA is weakly induced by LPS only (P < 0.05). Additionally, peptidoglycan downregulates the mRNA expression of adiponectin receptors, adipoR1 and adipoR2 (P < 0.05).</p> <p>Conclusion</p> <p>Obesity and type 2 diabetes are associated with increased expression of TLR2, this receptor could play a significant but previously unrecognized role in the establishment of chronic inflammation in adipose tissue in obesity.</p

(+)-Z-Bisdehydrodoisynolic Acid Enhances Basal Metabolism and Fatty Acid Oxidation in Female Obese Zucker Rats

We have previously reported that the synthetic estrogen, (+)-Z-bisdehydrodoisynolic Acid [(+)-Z-BDDA], attenuated weight gain and cardiovascular risk in obese rodents. To determine if these antiobesity effects were attributed to changes in basal metabolism, we assessed indirect calorimetry and metabolic profile in female obese Zucker (OZR) rats provided (+)-Z-BDDA (0.0002% food admixture) for 11 weeks. Similar to our previous findings, (+)-Z-BDDA reduced weight gain and improved lipid and glucose homeostasis in OZR rats. Furthermore, resting energy expenditure was increased by (+)-Z-BDDA, as evident by heat production and oxygen consumption. We also observed a marked reduction in respiratory quotient (RQ) along with a corresponding induction of hepatic AMPK in rodents provided (+)-Z-BDDA. Collectively, these findings indicate that (+)-Z-BDDA partially attenuated obesity and associated pathologies through increased resting energy expenditure and fatty acid utilization. Further investigation is required to fully elucidate the mechanisms involved as well as to determine the potential therapeutic implications for (+)-Z-BDDA on obesity and its related pathologies

Differential food protein-induced inflammatory responses in swine lines selected for reactivity to soy antigens

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151332/1/all13757.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151332/2/all13757_am.pd

Dietary Fat Content and Fiber Type Modulate Hind Gut Microbial Community and Metabolic Markers in the Pig

Obesity leads to changes in the gut microbial community which contribute to the metabolic dysregulation in obesity. Dietary fat and fiber affect the caloric density of foods. The impact of dietary fat content and fiber type on the microbial community in the hind gut is unknown. Effect of dietary fat level and fiber type on hindgut microbiota and volatile fatty acid (VFA) profiles was investigated. Expression of metabolic marker genes in the gut, adipose tissue and liver was determined. A 2×2 experiment was conducted in pigs fed at two dietary fat levels (5% or 17.5% swine grease) and two fiber types (4% inulin, fermentable fructo-oligosaccharide or 4% solka floc, non-fermentable cellulose). High fat diets (HFD) resulted in a higher (

Effect of phytase on intestinal phytate breakdown, plasma inositol concentrations and glucose transporter type 4 abundance in muscle membranes of weanling pigs

The objective of this current study was to determine the effects of phytase dosing on growth performance, mineral digestibility, phytate breakdown and the level of glucose transporter type 4 (GLUT4) in muscle plasma membranes of weanling pigs. A total of 160 barrows were used in a randomized completely block design and assigned to four treatments for a 7-week study. Depending on the feeding phase, diets differed in dietary calcium (Ca) and phosphorus (P) levels (PC:8 to 6.8g/kg Ca; 7.3 to 6.3 g/kg P; negative control (NC):5.5 to 5.2 g/kg Ca; 5.4 to 4.7 g/kg P). NC diets were supplemented with phytase at 0 (NC); 500 (NC+500 FTU) or 2000 FTU/kg (NC+2000 FTU) phytase units/kg. Blood was collected after fasting (d 48) or feeding (d 49) for measurement of plasma inositol concentrations. On d 49, two pigs per pen were euthanized, duodenal and ileal digesta samples were collected to determine inositol phosphates (InsP6-2) concentrations. High phytase supplementation increased body weight (BW) on d 21, 35 and 49 (P <0.05). Over the entire feeding period, average daily gain (ADG), average daily feed intake (ADFI) and feed efficiency were increased by NC+2000 FTU compared to the other treatments (P <0.05). Postprandial plasma inositol concentration was increased in NC+2000 (P < 0.01), but there was only a tendency (P = 0.06) of a higher fasting plasma inositol concentration in this group. Inositol concentrations in the portal vein plasma (d 49) were not different among treatments. Duodenal digesta InsP5 and InsP6 concentrations were similar in PC and NC, but higher in these two treatments (P < 0.05) than those supplemented with phytase. Phytase supplementation decreased InsP6-4, resulting in increased InsP3-2 and myo-inositol concentrations. Similar effects were found in ileal contents. Compared to NC, phytase supplementation resulted in greater cumulative InsP6-2 disappearance (93.6% vs. 72.8% vs. 25.0%, for NC+2000 FTU, NC +500 FTU and NC, respectively, P < 0.01) till the the distal ileum. Longissimus dorsi muscle plasma membrane GLUT4 concentration was increased by NC+2000 FTU (P < 0.01) compared to NC. In summary, high phytase supplementation increased growth performance of nursery pigs. The higher myo-inositol release from phytate could contribute to the increased expression of GLUT4 in muscle plasma membranes. Further investigation is needed to determine if this is associated with enhanced cellular glucose uptake and utilization

Mechanism of Butyrate Stimulation of Triglyceride Storage and Adipokine Expression during Adipogenic Differentiation of Porcine Stromovascular Cells.

Short chain fatty acids (SCFA), products of microbial fermentation of dietary fiber, exert multiple metabolic effects in cells. Previously, we had demonstrated that soluble fiber influenced fat mass accumulation, gut microbial community structure and SCFA production in pigs. The current study was designed to identify effects of SCFA treatment during adipogenic differentiation of porcine stromovascular cells on lipid metabolism and adipokine expression. Differentiating cells were treated with varying concentrations of butyrate. Results show that butyrate treatment enhanced adipogenesis and lipid accumulation, perhaps through upregulation of glucose uptake and de novo lipogenesis and other mechanisms that include induction of SREBP-1c, C/EBPα/β, GLUT4, LPL, PPARγ, GPAT4, DGAT1 and DGAT2 expression. In addition, butyrate induced adiponectin expression, resulting in activation of downstream target genes, such as AMPK and AKT. Activation of AMPK by butyrate led to phosphorylation of ACC. Although increased ACO gene expression was seen with butyrate treatment, experiments with the peroxisomal fatty acid inhibitor, thioridazine, suggest that butyrate may have an inhibitory effect on peroxisomal fatty acid oxidation. Our studies also provide evidence that butyrate may inhibit lipolysis, perhaps in an FFAR3-dependent manner. Therefore, this study presents a novel paradigm for butyrate action in adipocytes and shows that adipocytes are capable of utilizing butyrate, leading to increased expression of adiponectin for enhanced glucose uptake and improved insulin sensitivity

Effects of Diets Differing in Composition of 18-C Fatty Acids on Adipose Tissue Thermogenic Gene Expression in Mice Fed High-Fat Diets

Dietary fatty acids play important roles in the regulation of fat accumulation or metabolic phenotype of adipocytes, either as brown or beige fat. However, a systematic comparison of effects of diets with different composition of 18-C fatty acids on browning/beiging phenotype has not been done. In this study, we compared the effects of different dietary fats, rich in specific 18-carbon fatty acids, on thermogenesis and lipid metabolism. Male C57BL/6 mice were fed a control diet containing 5.6% kcal fat from lard and 4.4% kcal fat from soybean oil (CON) or high-fat diets (HFD) containing 25% kcal from lard and 20% kcal fat from shea butter (stearic acid-rich fat; SHB), olive oil (oleic acid-rich oil; OO), safflower oil (linoleic acid-rich oil; SFO), or soybean oil (mixed oleic, linoleic, and α-linolenic acids; SBO) ad libitum for 12 weeks, with or without a terminal 4-h norepinephrine (NE) treatment. When compared to SHB, feeding OO, SFO, and SBO resulted in lower body weight gain. The OO fed group had the highest thermogenesis level, which resulted in lower body fat accumulation and improved glucose and lipid metabolism. Feeding SFO downregulated expression of lipid oxidation-related genes and upregulated expression of lipogenic genes, perhaps due to its high n-6:n-3 ratio. In general, HFD-feeding downregulated Ucp1 expression in both subcutaneous and epididymal white adipose tissue, and suppressed NE-induced Pgc1a expression in brown adipose tissue. These results suggest that the position of double bonds in dietary fatty acids, as well as the quantity of dietary fat, may have a significant effect on the regulation of oxidative and thermogenic conditions in vivo

Butyrate modifies intestinal barrier function in IPEC-J2 cells through a selective upregulation of tight junction proteins and activation of the Akt signaling pathway

<div><p>The intestinal epithelial barrier, composed of epithelial cells, tight junction proteins and intestinal secretions, prevents passage of luminal substances and antigens through the paracellular space. Dysfunction of the intestinal barrier integrity induced by toxins and pathogens is associated with a variety of gastrointestinal disorders and diseases. Although butyrate is known to enhance intestinal health, its role in the protection of intestinal barrier function is poorly characterized. Therefore, we investigated the effect of butyrate on intestinal epithelial integrity and tight junction permeability in a model of LPS-induced inflammation in IPEC-J2 cells. Butyrate dose-dependently reduced LPS impairment of intestinal barrier integrity and tight junction permeability, measured by trans-epithelial electrical resistance (TEER) and paracellular uptake of fluorescein isothiocyanate-dextran (FITC-dextran). Additionally, butyrate increased both mRNA expression and protein abundance of claudins-3 and 4, and influenced intracellular ATP concentration in a dose-dependent manner. Furthermore, butyrate prevented the downregulation of Akt and 4E-BP1 phosphorylation by LPS, indicating that butyrate might enhance tight junction protein abundance through mechanisms that included activation of Akt/mTOR mediated protein synthesis. The regulation of AMPK activity and intracellular ATP level by butyrate indicates that butyrate might regulate energy status of the cell, perhaps by serving as a nutrient substrate for ATP synthesis, to support intestinal epithelial barrier tight junction protein abundance. Our findings suggest that butyrate might protect epithelial cells from LPS-induced impairment of barrier integrity through an increase in the synthesis of tight junction proteins, and perhaps regulation of energy homeostasis.</p></div

Biglycan deletion alters adiponectin expression in murine adipose tissue and 3T3-L1 adipocytes.

Obesity promotes increased secretion of a number of inflammatory factors from adipose tissue. These factors include cytokines and very lately, extracellular matrix components (ECM). Biglycan, a small leucine rich proteoglycan ECM protein, is up-regulated in obesity and has recently been recognized as a pro-inflammatory molecule. However, it is unknown whether biglycan contributes to adipose tissue dysfunction. In the present study, we characterized biglycan expression in various adipose depots in wild-type mice fed a low fat diet (LFD) or obesity-inducing high fat diet (HFD). High fat feeding induced biglycan mRNA expression in multiple adipose depots. Adiponectin is an adipokine with anti-inflammatory and insulin sensitizing effects. Due to the importance of adiponectin, we examined the effect of biglycan on adiponectin expression. Comparison of adiponectin expression in biglycan knockout (bgn(-/0)) and wild-type (bgn(+/0)) reveals higher adiponectin mRNA and protein in epididymal white adipose tissue in bgn(-/0) mice, as well higher serum concentration of adiponectin, and lower serum insulin concentration. On the contrary, knockdown of biglycan in 3T3-L1 adipocytes led to decreased expression and secretion of adiponectin. Furthermore, treatment of 3T3-L1 adipocytes with conditioned medium from biglycan treated macrophages resulted in an increase in adiponectin mRNA expression. These data suggest a link between biglycan and adiponectin expression. However, the difference in the pattern of regulation between in vivo and in vitro settings reveals the complexity of this relationship