Akkermansia muciniphila and its membrane protein ameliorates intestinal inflammatory stress and promotes epithelial wound healing via CREBH and miR-143/145.

BACKGROUND: The intestinal epithelial barrier is the interface for interaction between gut microbiota and host metabolic systems. Akkermansia muciniphila (A. muciniphila) is a key player in the colonic microbiota that resides in the mucus layer, whose abundance is selectively decreased in the faecal microbiota of inflammatory bowel disease (IBD) patients. This study aims to investigate the regulatory mechanism among A. muciniphila, a transcription factor cAMP-responsive element-binding protein H (CREBH), and microRNA-143/145 (miR-143/145) in intestinal inflammatory stress, gut barrier integrity and epithelial regeneration. METHODS: A novel mouse model with increased colonization of A muciniphila in the intestine of CREBH knockout mice, an epithelial wound healing assay and several molecular biological techniques were applied in this study. Results were analysed using a homoscedastic 2-tailed t-test. RESULTS: Increased colonization of A. muciniphila in mouse gut enhanced expression of intestinal CREBH, which was associated with the mitigation of intestinal endoplasmic reticulum (ER) stress, gut barrier leakage and blood endotoxemia induced by dextran sulfate sodium (DSS). Genetic depletion of CREBH (CREBH-KO) significantly inhibited the expression of tight junction proteins that are associated with gut barrier integrity, including Claudin5 and Claudin8, but upregulated Claudin2, a tight junction protein that enhances gut permeability, resulting in intestinal hyperpermeability and inflammation. Upregulation of CREBH by A. muciniphila further coupled with miR-143/145 promoted intestinal epithelial cell (IEC) regeneration and wound repair via insulin-like growth factor (IGF) and IGFBP5 signalling. Moreover, the gene expressing an outer membrane protein of A. muciniphila, Amuc_1100, was cloned into a mammalian cell-expression vector and successfully expressed in porcine and human IECs. Expression of Amuc_1100 in IECs could recapitulate the health beneficial effect of A. muciniphila on the gut by activating CREBH, inhibiting ER stress and enhancing the expression of genes involved in gut barrier integrity and IEC's regeneration. CONCLUSIONS: This study uncovers a novel mechanism that links A. muciniphila and its membrane protein with host CREBH, IGF signalling and miRNAs in mitigating intestinal inflammatory stress-gut barrier permeability and promoting intestinal wound healing. This novel finding may lend support to the development of therapeutic approaches for IBD by manipulating the interaction between host genes, gut bacteria and its bioactive components.

Rho/ROCK mechanosensor in adipocyte stiffness and traction force generation.

It is increasingly recognized that interaction of adipose cells with extracellular mechanophysical milieus may play a role in regulating adipogenesis and differentiated adipocyte function and such interaction can be mediated by the mechanics of adipose cells. We measured the stiffness and traction force of adipose cells and examined the role of Rho/ROCK, the upstream effector of actin cytoskeletal contractility, in affecting these mechanical properties. Cellular Young's modulus obtained from atomic force microscopy (AFM) was significantly reduced by ROCK inhibitor (Y-27632) but elevated by Rho activator (CN01), for both preadipocytes and differentiated adipocytes. Immunofluorescent imaging suggested this could be attributed to the changes in Rho/ROCK-induced stressed actin filament formation. AFM also confirmed that differentiated adipocytes had higher stiffness than preadipocytes. On the other hand, traction force microscopy (TFM) revealed differentiated adipocytes exerted lower traction forces than preadipocytes. Traction forces of both preadipocytes and adipocytes were decreased by ROCK inhibition, but not significantly altered by Rho activation. Notably, an increasing trend of traction force with respect to cell spreading area was detected, and this trend was substantially amplified by Rho activation. Such traction force-cell area correlation was an order-of-magnitude smaller for differentiated adipocytes relative to preadipocytes, potentially due to disrupted force transmission through cytoskeleton-focal adhesion linkage by lipid droplets. Our work provides new data evidencing the Rho/ROCK control in adipose cell mechanics, laying the groundwork for adipocyte mechanotransduction studies on adipogenesis and adipose tissue remodeling.

A review of the role of ethanol-induced adipose tissue dysfunction in alcohol-associated liver disease.

Alcohol-associated liver disease (AALD) encompasses a spectrum of liver diseases that includes simple steatosis, steatohepatitis, fibrosis, and cirrhosis. The adverse effects of alcohol in liver and the mechanisms by which ethanol (EtOH) promotes liver injury are well studied. Although liver is known to be the primary organ affected by EtOH exposure, alcohol's effects on other organs are also known to contribute significantly to the development of liver injury. It is becoming increasingly evident that adipose tissue (AT) is an important site of EtOH action. Both AT storage and secretory functions are altered by EtOH. For example, AT lipolysis, stimulated by EtOH, contributes to chronic alcohol-induced hepatic steatosis. Adipocytes secrete a wide variety of biologically active molecules known as adipokines. EtOH alters the secretion of these adipokines from AT, which include cytokines and chemokines that exert paracrine effects in liver. In addition, the level of EtOH-metabolizing enzymes, in particular, CYP2E1, rises in the AT of EtOH-fed mice, which promotes oxidative stress and/or inflammation in AT. Thus, AT dysfunction characterized by increased AT lipolysis and free fatty acid mobilization and altered secretion of adipokines can contribute to the severity of AALD. Of note, moderate EtOH exposure results in AT browning and activation of brown adipose tissue which, in turn, can promote thermogenesis. In this review article, we discuss the direct effects of EtOH consumption in AT and the mechanisms by which EtOH impacts the functions of AT, which, in turn, increases the severity of AALD in animal models and humans.

Nanoformulated SOD1 ameliorates the combined NASH and alcohol-associated liver disease partly via regulating CYP2E1 expression in adipose tissue and liver.

Enhanced free fatty acid (FFA) flux from adipose tissue (AT) to liver plays an important role in the development of nonalcoholic steatohepatitis (NASH) and alcohol-associated liver disease (AALD). We determined the effectiveness of nanoformulated superoxide dismutase 1 (Nano) in attenuating liver injury in a mouse model exhibiting a combination of NASH and AALD. Male C57BL6/J mice were fed a chow diet (CD) or a high-fat diet (HF) for 10 wk followed by pair feeding of the Lieber-DeCarli control (control) or ethanol (ET) diet for 4 wk. Nano was administered once every other day for the last 2 wk of ET feeding. Mice were divided into 1) CD + control diet (CD + Cont), 2) high-fat diet (HF) + control diet (HF + Cont), 3) HF + Cont + Nano, 4) HF + ET diet (HF + ET), and 5) HF + ET + Nano. The total fat mass, visceral AT mass (VAT), and VAT perilipin 1 content were significantly lower only in HF + ET-fed mice but not in HF + ET + Nano-treated mice compared with controls. The HF + ET-fed mice showed an upregulation of VAT CYP2E1 protein, and Nano abrogated this effect. We noted a significant rise in plasma FFAs, ALT, and monocyte chemoattractant protein-1 in HF + ET-fed mice, which was blunted in HF + ET + Nano-treated mice. HF + ET-induced increases in hepatic steatosis and inflammatory markers were attenuated upon Nano treatment. Nano reduced hepatic CYP2E1 and enhanced catalase levels in HF + ET-fed mice with a concomitant increase in SOD1 protein and activity in liver. Nano was effective in attenuating AT and liver injury in mice exhibiting a combination of NASH and AALD, partly via reduced CYP2E1-mediated ET metabolism in these organs.NEW & NOTEWORTHY Increased free fatty acid flux from adipose tissue (AT) to liver accompanied by oxidative stress promotes nonalcoholic steatohepatitis (NASH) and alcohol-associated liver injury (AALD). Obesity increases the severity of AALD. Using a two-hit model involving a high-fat diet and chronic ethanol feeding to mice, and treating them with nanoformulated superoxide dismutase (nanoSOD), we have shown that nanoSOD improves AT lipid storage, reduces CYP2E1 in AT and liver, and attenuates the combined NASH/AALD in mice.

Nanoformulated copper/zinc superoxide dismutase attenuates vascular cell activation and aortic inflammation in obesity.

OBJECTIVE: Endothelial cell (EC) oxidative stress can lead to vascular dysfunction which is an underlying event in the development of cardiovascular disease (CVD). The lack of a potent and bioavailable anti-oxidant enzyme is a major challenge in studies on antioxidant therapy. The objective of this study is to determine whether copper/zinc superoxide dismutase (CuZnSOD or SOD1) after nanoformulation (nanoSOD) can effectively reduce EC oxidative stress and/or vascular inflammation in obesity. METHODS: Human aortic endothelial cells (HAECs) were treated with native- or nanoSOD for 6 h followed by treatment with linoleic acid (LA), a free fatty acid, for 6-24 h. To determine the in vivo relevance, the effectiveness of nanoSOD in reducing vascular cell activation was studied in a mouse model of diet-induced obesity. RESULTS: We noted that nanoSOD was more effectively taken up by ECs than native SOD. Western blot analysis further confirmed that the intracellular accumulation of SOD1 protein was greatly increased upon nanoSOD treatment. Importantly, nanoSOD pretreatment led to a significant decrease in LA-induced oxidative stress in ECs which was associated with a marked increase in SOD enzyme activity in ECs. In vivo studies showed a significant decrease in markers of EC/vascular cell activation and/or inflammation in visceral adipose tissue (VAT), thoracic aorta, and heart collected from nanoSOD-treated mice compared to obese control mice. Interestingly, the expression of metallothionein 2, an antioxidant gene was significantly increased in nanoSOD-treated mice. CONCLUSION: Our data show that nanoSOD is very effective in delivering active SOD to ECs and in reducing EC oxidative stress. Our data also demonstrate that nanoSOD will be a useful tool to reduce vascular cell activation in VAT and aorta in obesity which, in turn, can protect against obesity-associated CVD, in particular, hypertension.

A Pilot Study on the Proteomics Profile of Serum Exosome-Enriched Extracellular Vesicles from Normal versus Individuals with Obesity-Related Insulin Resistance.

OBJECTIVE: Circulating exosome-enriched extracellular vesicles (EVs) have drawn considerable importance in obesity-related insulin-resistance (IR). We sought to compare the proteomics profile of serum exosomes from normal individuals and those with obesity and IR. METHODS: We isolated serum exosomes from male subjects with obesity and insulin resistance (Ob-IR, HOMA-IR > 2.0) and lean/overweight insulin-sensitive (Normal (N), HOMA-IR < 2.0) individuals. The differential protein expression between the two groups was detected by a label-free quantitative mass spectrometry analysis followed by GO annotation and ingenuity pathway analysis (IPA). RESULTS: We identified 23 upregulated and 46 downregulated proteins between Ob-IR and N groups. Some of these proteins are involved in altering insulin signaling (VPS13C, TBC1D32, TTR, and ADIPOQ), inflammation (NFκB and CRP), and B-cell proliferation/activation (IGLV4-69, IGKV1D-13, and IGHV4-28). GO analysis revealed that the differentially expressed proteins (DEPs) are mainly involved in regulating immune cell activation and are located in extracellular space. IPA analysis showed that top molecules mediating IR, inflammation and B-cell activation were upregulated in Ob-IR subjects compared to N subjects. CONCLUSIONS: Serum exosomal proteins can be used as biomarkers to identify the future risk of diabetes and a therapeutic target to prevent or slow down the progression of diabetes in high-risk individuals.

Effect of Ethanol on Exosome Biogenesis: Possible Mechanisms and Therapeutic Implications.

Most eukaryotic cells, including hepatocytes, secrete exosomes into the extracellular space, which are vesicles facilitating horizontal cell-to-cell communication of molecular signals and physiological cues. The molecular cues for cellular functions are carried by exosomes via specific mRNAs, microRNAs, and proteins. Exosomes released by liver cells are a vital part of biomolecular communication in liver diseases. Importantly, exosomes play a critical role in mediating alcohol-associated liver disease (ALD) and are potential biomarkers for ALD. Moreover, alcohol exposure itself promotes exosome biogenesis and release from the livers of humans and rodent models. However, the mechanisms by which alcohol promotes exosome biogenesis in hepatocytes are still unclear. Of note, alcohol exposure leads to liver injury by modulating various cellular processes, including autophagy, ER stress, oxidative stress, and epigenetics. Evidence suggests that there is a link between each of these processes with exosome biogenesis. The aim of this review article is to discuss the interplay between ethanol exposure and these altered cellular processes in promoting hepatocyte exosome biogenesis and release. Based on the available literature, we summarize and discuss the potential mechanisms by which ethanol induces exosome release from hepatocytes, which in turn leads to the progression of ALD.

NLRP3: a new therapeutic target in alcoholic liver disease.

The liver is in charge of a wide range of critical physiological processes and it plays an important role in activating the innate immune system which elicits the inflammatory events. Chronic ethanol exposure disrupts hepatic inflammatory mechanism and leads to the release of proinflammatory mediators such as chemokines, cytokines and activation of inflammasomes. The mechanism of liver fibrosis/cirrhosis involve activation of NLRP3 inflammasome, leading to the destruction of hepatocytes and subsequent metabolic dysregulation in humans. In addition, increasing evidence suggests that alcohol intake significantly modifies liver epigenetics, promoting the development of alcoholic liver disease (ALD). Epigenetic changes including histone modification, microRNA-induced genetic modulation, and DNA methylation are crucial in alcohol-evoked cell signaling that affects gene expression in the hepatic system. Though we are at the beginning stage without having the entire print of epigenetic signature, it is time to focus more on NLRP3 inflammasome and epigenetic modifications. Here we review the novel aspect of ALD pathology linking to inflammation and highlighting the role of epigenetic modification associated with NLRP3 inflammasome and how it could be a therapeutic target in ALD.

Histidine Enhances the Anticancer Effect of Gemcitabine against Pancreatic Cancer via Disruption of Amino Acid Homeostasis and Oxidant-Antioxidant Balance.

Due to the severe toxicity posed by chemotherapeutic drugs, adjuvant nutritional intervention has gained increased attention in the treatment of pancreatic cancer (PC). Amino acid (AA) metabolism is aberrantly regulated in PC and circulating histidine (His) levels are low in PC patients. We hypothesized that His uptake and/or metabolism is dysregulated in PC and that combining His with gemcitabine (Gem), a drug used in the treatment of PC, will enhance the anti-cancer effects of Gem. We performed in vitro and in vivo studies to determine the anticancer effect of the combination of His and Gem against lethal PC. We demonstrate that circulating His levels are low in both human subjects and genetically engineered mice exhibiting pancreatic tumors. Interestingly, the expression of histidine ammonia lyase, an enzyme involved in His catabolism, is higher in PC compared to normal subjects. His + Gem exerts a more potent cytotoxic effect in PC cells compared to individual treatments. His treatment results in a profound increase in His accumulation, accompanied by a depletion of a number of AAs, promoting cancer cell survival and/or glutathione (GSH) synthesis. His but not Gem increases hydrogen peroxide and depletes cellular GSH. Supplementation with GSH protects cells against His + Gem-induced cytotoxicity. Further, our in vivo studies demonstrate that His + Gem potently reduced tumor mass and improved mouse survival. Taken together, our data suggest that PC cells exhibit an aberrant His uptake/accumulation which, in turn, leads to oxidative stress and depletion of AA pool, thereby enhancing the anticancer effect of Gem.

Fish oil and indomethacin in combination potently reduce dyslipidemia and hepatic steatosis in LDLR(-/-) mice.

Fish oil (FO) is a potent anti-inflammatory and lipid-lowering agent. Because inflammation can modulate lipid metabolism and vice versa, we hypothesized that combining FO with cyclooxygenase inhibitors (COXIBs), well-known anti-inflammatory drugs, can enhance the anti-inflammatory and lipid-lowering effect of FO. LDLR(-/-) mice were fed a high-fat diet supplemented with 6% olive oil or FO for 12 wk in the presence or absence of indomethacin (Indo, 6 mg/l drinking water). FO reduced plasma total cholesterol by 30% but, in combination with Indo, exerted a greater decrease (44%). The reduction of liver cholesterol ester (CE) and triglycerides (TG) by FO (63% and 41%, respectively) was enhanced by Indo (80% in CE and 64% in TG). FO + Indo greatly increased the expression of genes modulating lipid metabolism and reduced the expression of inflammatory genes compared with control. The mRNA and/or protein expression of pregnane X receptor (PXR) and cytochrome P450 isoforms that alter inflammation and/or lipid metabolism are increased to a greater extent in mice that received FO + Indo. Moroever, the nuclear level of PXR is significantly increased in FO + Indo group. Combining FO with COXIBs may exert their beneficial effects on inflammation and lipid metabolism via PXR and cytochrome P450.

Myristic Acid Supplementation Aggravates High Fat Diet-Induced Adipose Inflammation and Systemic Insulin Resistance in Mice.

Saturated fatty acids (SFAs) are considered to be detrimental to human health. One of the SFAs, myristic acid (MA), is known to exert a hypercholesterolemic effect in mice as well as humans. However, its effects on altering adipose tissue (AT) inflammation and systemic insulin resistance (IR) in obesity are still unclear. Here, we sought to determine the effects of a high fat (HF) diet supplemented with MA on obesity-associated metabolic disorders in mice. Wild-type C57BL/6 mice were fed a HF diet in the presence or absence of 3% MA for 12 weeks. Plasma lipids, plasma adipokines, AT inflammation, systemic IR, glucose homeostasis, and hepatic steatosis were assessed. The body weight and visceral adipose tissue (VAT) mass were significantly higher in mice receiving the HF+MA diet compared to HF diet-fed controls. Plasma total cholesterol levels were marginally increased in HF+MA-fed mice compared to controls. Fasting blood glucose was comparable between HF and HF+MA-fed mice. Interestingly, the plasma insulin and HOMA-IR index, a measure of insulin resistance, were significantly higher in HF+MA-fed mice compared to HF controls. Macrophage and inflammatory markers were significantly elevated in the AT and AT-derived stromal vascular cells upon MA feeding. Moreover, the level of circulating resistin, an adipokine promoting insulin resistance, was significantly higher in HF+MA-fed mice compared with HF controls. The insulin tolerance test revealed that the IR was higher in mice receiving the MA supplementation compared to HF controls. Moreover, the glucose tolerance test showed impairment in systemic glucose homeostasis in MA-fed mice. Analyses of liver samples showed a trend towards an increase in liver TG upon MA feeding. However, markers of oxidative stress and inflammation were reduced in the liver of mice fed an MA diet compared to controls. Taken together, our data suggest that chronic administration of MA in diet exacerbates obesity-associated insulin resistance and this effect is mediated in part, via increased AT inflammation and increased secretion of resistin.

Defective phagocytosis of apoptotic cells by macrophages in atherosclerotic lesions of ob/ob mice and reversal by a fish oil diet.

RATIONALE: The complications of atherosclerosis are a major cause of death and disability in type 2 diabetes. Defective clearance of apoptotic cells by macrophages (efferocytosis) is thought to lead to increased necrotic core formation and inflammation in atherosclerotic lesions. OBJECTIVE: To determine whether there is defective efferocytosis in a mouse model of obesity and atherosclerosis. METHODS AND RESULTS: We quantified efferocytosis in peritoneal macrophages and in atherosclerotic lesions of obese ob/ob or ob/ob;Ldlr(-/-) mice and littermate controls. Peritoneal macrophages from ob/ob and ob/ob;Ldlr(-/-) mice showed impaired efferocytosis, reflecting defective phosphatidylinositol 3-kinase activation during uptake of apoptotic cells. Membrane lipid composition of ob/ob and ob/ob;Ldlr(-/-) macrophages showed an increased content of saturated fatty acids (FAs) and decreased omega-3 FAs (eicosapentaenoic acid and docosahexaenoic acid) compared to controls. A similar defect in efferocytosis was induced by treating control macrophages with saturated free FA/BSA complexes, whereas the defect in ob/ob macrophages was reversed by treatment with eicosapentaenoic acid/BSA or by feeding ob/ob mice a fish oil diet rich in omega-3 FAs. There was also defective macrophage efferocytosis in atherosclerotic lesions of ob/ob;Ldlr(-/-) mice and this was reversed by a fish oil-rich diet. CONCLUSIONS: The findings suggest that in obesity and type 2 diabetes elevated levels of saturated FAs and/or decreased levels of omega-3 FAs contribute to decreased macrophage efferocytosis. Beneficial effects of fish oil diets in atherosclerotic cardiovascular disease may involve improvements in macrophage function related to reversal of defective efferocytosis and could be particularly important in type 2 diabetes and obesity.

Natural Recovery by the Liver and Other Organs after Chronic Alcohol Use.

Chronic, heavy alcohol consumption disrupts normal organ function and causes structural damage in virtually every tissue of the body. Current diagnostic terminology states that a person who drinks alcohol excessively has alcohol use disorder. The liver is especially susceptible to alcohol-induced damage. This review summarizes and describes the effects of chronic alcohol use not only on the liver, but also on other selected organs and systems affected by continual heavy drinking-including the gastrointestinal tract, pancreas, heart, and bone. Most significantly, the recovery process after cessation of alcohol consumption (abstinence) is explored. Depending on the organ and whether there is relapse, functional recovery is possible. Even after years of heavy alcohol use, the liver has a remarkable regenerative capacity and, following alcohol removal, can recover a significant portion of its original mass and function. Other organs show recovery after abstinence as well. Data on studies of both heavy alcohol use among humans and animal models of chronic ethanol feeding are discussed. This review describes how (or whether) each organ/tissue metabolizes ethanol, as metabolism influences the organ's degree of injury. Damage sustained by the organ/tissue is reviewed, and evidence for recovery during abstinence is presented.

Inhibition of long-chain acyl coenzyme A synthetases during fatty acid loading induces lipotoxicity in macrophages.

OBJECTIVE: Obesity is often associated with hypertriglyceridemia and elevated free fatty acids (FFAs), which are independent risk factors for cardiovascular disease and diabetes. Although impairment of cholesterol homeostasis is known to induce toxicity in macrophages, the consequence of altered fatty acid homeostasis is not clear. METHODS AND RESULTS: Long-chain acyl CoA synthetases (ACSLs) play a critical role in fatty acid homeostasis by channeling fatty acids to diverse metabolic pools. We treated mouse peritoneal macrophages (MPMs) with VLDL or FFAs in the presence of triacsin C, an inhibitor of the 3 ACSL isoforms present in macrophages. Treatment of macrophages with VLDL and triacsin C resulted in reduced TG accumulation but increased intracellular FFA levels, which induced lipotoxicity characterized by apoptosis. Treatment of MPMs with the saturated fatty acid stearic acid in the presence of triacsin C increased intracellular stearic acid and induced apoptosis. Stromal vascular cells collected from high-fat diet-fed mice displayed foam cell morphology and exhibited increased mRNA levels of macrophage markers and ACSL1. Importantly, all of these changes were associated with increased FFA level in AT. CONCLUSIONS: Inhibition of ACSLs during fatty acid loading results in apoptosis via accumulation of FFAs. Our data have implications in understanding the consequences of dysregulated fatty acid metabolism in macrophages.

A combination of Omega-3 PUFAs and COX inhibitors: A novel strategy to manage obesity-linked dyslipidemia and adipose tissue inflammation.

We previously reported that fish oil in combination with cyclooxygenase (COX) inhibitors exerts enhanced hypolipidemic and anti-inflammatory effects in mice. Here, we sought to determine the effects of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in combination with naproxen (NX), a COX inhibitor, on dyslipidemia and gene expression in adipose tissue (AT) in humans. Obese dyslipidemic patients were randomly assigned to one of these interventions for 12 wk: 1) Standard nutrition counseling (control), 2) ω-3 PUFAs (2 g twice daily), 3) NX (220 mg twice daily), and 4) ω-3 PUFAs (2 g twice daily) + NX (220 mg twice daily). The serum triglycerides showed a trend towards a reduction and a significant reduction (P<0.05) in ω-3 and ω3 + NX-treated subjects, respectively, compared to control. The mRNA expression of vascular cell adhesion molecule-1 (Vcam1), an inflammatory marker, increased significantly in AT of ω-3 PUFA-treated subjects but not in ω-3 PUFAs+NX-treated group. The plasma level of glycine-conjugated hyodeoxycholic acid, a secondary bile acid with hypolipidemic property, increased significantly in ω-3 PUFAs + NX-treated group. Our data suggest that combining NX with ω-3 PUFAs increases their effectiveness in reducing serum TG and favorably altering AT gene expression and plasma bile acid profile.

Lauric Acid versus Palmitic Acid: Effects on Adipose Tissue Inflammation, Insulin Resistance, and Non-Alcoholic Fatty Liver Disease in Obesity.

Coconut oil, rich in medium-chain saturated fatty acids (MCSFA), in particular, lauric acid (LA), is known to exert beneficial metabolic effects. Although LA is the most abundant saturated fatty acid in coconut oil, the specific role of LA in altering obesity-related metabolic disorders remains unknown. Here, we examined the effects of supplementing a high fat (HF) diet with purified LA on obesity-associated metabolic derangements in comparison with palmitic acid (PA), a long-chain saturated fatty acid. Male C57BL/6 mice were fed a control chow diet (CD) or an HF diet supplemented with 3% LA (HF + LA) or PA (HF + PA) for 12 wk. Markers of adipose tissue (AT) inflammation, systemic insulin resistance (IR), and hepatic steatosis, were assessed. The body weight and total fat mass were significantly higher in both HF + LA and HF + PA diet-fed groups compared to CD controls. However, the visceral adipose tissue (VAT) mass was significantly higher (p < 0.001) in HF + LA-fed mice compared to both CD as well as HF + PA-fed mice. Interestingly, markers of AT inflammation were promoted to a lesser extent in HF + LA-fed mice compared to HF + PA-fed mice. Thus, immunohistochemical analysis of VAT showed an increase in MCP-1 and IL-6 staining in HF + PA-fed mice but not in HF + LA-fed mice compared to CD controls. Further, the mRNA levels of macrophage and inflammatory markers were significantly higher in HF + PA-fed mice (p < 0.001) whereas these markers were increased to a lesser extent in HF + LA-fed group. Of note, the insulin tolerance test revealed that IR was significantly increased only in HF + PA-fed mice but not in HF + LA-fed group compared to CD controls. While liver triglycerides were increased significantly in both HF + PA and HF + LA-fed mice, liver weight and plasma markers of liver injury such as alanine aminotransferase and aspartate aminotransferase were increased significantly only in HF + PA-fed mice but not in HF + LA-fed mice. Taken together, our data suggest that although both LA and PA increased AT inflammation, systemic IR, and liver injury, the extent of metabolic derangements caused by LA was less compared to PA in the setting of high fat feeding.

Dietary fish oil exerts hypolipidemic effects in lean and insulin sensitizing effects in obese LDLR-/- mice.

Obesity is often associated with dyslipidemia, insulin resistance, and hypertension. Together, these metabolic perturbations greatly increase the risk of developing cardiovascular disease and diabetes. Although fish oil is a well-established hypolipidemic agent, the mechanisms by which it mediates its lipid-lowering effects are not clear. In addition, it has not been established whether dietary fish oil has different effects in lean and obese mice. LDL receptor deficient (LDLR-/-) and leptin deficient mice on a LDLR-/- background (ob/ob;LDLR-/-) were fed a high fat diet (39% total fat) supplemented with 6% olive oil or fish oil for 6 wk. Fish oil supplementation resulted in lower concentrations of plasma total cholesterol (P < 0.01), triglycerides (P < 0.01), and free fatty acids (P < 0.001) in lean LDLR-/- mice, but not in ob/ob;LDLR-/- mice. In contrast, a fish oil diet did not modulate insulin sensitivity in lean LDLR-/- mice, but it improved insulin sensitivity in ob/ob;LDLR-/- mice (P < 0.05) compared with olive oil fed ob/ob;LDLR-/- mice. Interestingly, plasma adiponectin concentrations were significantly higher and hepatic steatosis was reduced in both mouse models upon fish oil feeding. Finally, fish oil fed LDLR-/- mice exhibited higher hepatic AMP activated protein kinase (AMPK) phosphorylation (P < 0.05), whereas AMPK phosphorylation was not elevated by fish oil feeding in ob/ob;LDLR-/- mice. Taken together, our data suggest that fish oil reduces hepatic steatosis in both lean and obese mice, has potent plasma lipid lowering effects in lean mice, and exerts insulin sensitizing effects in obese mice.

Effect of nanoformulated copper/zinc superoxide dismutase on chronic ethanol-induced alterations in liver and adipose tissue.

BACKGROUND: We previously reported that nanoformulated copper/zinc superoxide dismutase (Nano) attenuates non-alcoholic fatty liver disease and adipose tissue (AT) inflammation in obese animals. Here, we sought to determine whether Nano treatment attenuates alcohol-associated liver disease (AALD) and AT inflammation in alcohol-fed mice. METHODS: We pre-treated E-47 cells (HepG2 cells that over-express CYP2E1) with native- or nano-superoxide dismutase (SOD) for 6 h, followed by treatment with ethanol and/or linoleic acid (LA), a free fatty acid. For in vivo studies, male C57BL/6 mice were fed the Lieber-DeCarli control or ethanol liquid diet for 4 weeks. The mice received Nano once every 2 days during the last 2 weeks of ethanol feeding. RESULTS: Our in vitro studies revealed that Nano pretreatment reduced LA + ethanol-induced oxidative stress in E-47 cells. Our in vivo experiments showed that ethanol-fed Nano-treated mice had 22% lower hepatic triglyceride levels than mice fed ethanol alone. Nano-treated ethanol-fed mice also had 2-fold lower levels of Cd68 and similarly reduced levels of Ccl2 and Mmp12 mRNAs, than in untreated ethanol-fed mice. We also noted that ethanol feeding caused a remarkable increase in hepatic and/or plasma MCP-1 and CCR2 protein, which was blunted in ethanol + Nano-treated animals. The hepatic content of SREBP-1c, a transcription factor that promotes lipogenesis, was higher in ethanol-fed mice than controls but was attenuated in ethanol + Nano-treated animals. Further, livers of ethanol + Nano-treated mice had significantly higher levels of phosphorylated adenosine monophosphate-activated protein kinase (AMPK) than both control and ethanol-fed mice. In AT, the levels of Il6 mRNA, a hepatoprotective cytokine, and that of Arg1, a marker of anti-inflammatory macrophages, were significantly increased in ethanol + Nano-treated mice compared with control mice. CONCLUSION: Our data indicate that Nano treatment attenuates ethanol-induced steatohepatitis and that this effect is associated with an apparent activation of AMPK signaling. Our data also suggest that Nano induces Arg1 and Il6 expression in AT, suggesting anti-inflammatory effects in this tissue.

Pancreatic cancer associated with obesity and diabetes: an alternative approach for its targeting.

BACKGROUND: Pancreatic cancer (PC) is among foremost causes of cancer related deaths worldwide due to generic symptoms, lack of effective screening strategies and resistance to chemo- and radiotherapies. The risk factors associated with PC include several metabolic disorders such as obesity, insulin resistance and type 2 diabetes mellitus (T2DM). Studies have shown that obesity and T2DM are associated with PC pathogenesis; however, their role in PC initiation and development remains obscure. MAIN BODY: Several biochemical and physiological factors associated with obesity and/or T2DM including adipokines, inflammatory mediators, and altered microbiome are involved in PC progression and metastasis albeit by different molecular mechanisms. Deep understanding of these factors and causal relationship between factors and altered signaling pathways will facilitate deconvolution of disease complexity as well as lead to development of novel therapies. In the present review, we focuses on the interplay between adipocytokines, gut microbiota, adrenomedullin, hyaluronan, vanin and matrix metalloproteinase affected by metabolic alteration and pancreatic tumor progression. CONCLUSIONS: Metabolic diseases, such as obesity and T2DM, contribute PC development through altered metabolic pathways. Delineating key players in oncogenic development in pancreas due to metabolic disorder could be a beneficial strategy to combat cancers associated with metabolic diseases in particular, PC.

Nanoformulated copper/zinc superoxide dismutase exerts differential effects on glucose vs lipid homeostasis depending on the diet composition possibly via altered AMPK signaling.

Evidence suggests that superoxide dismutase 1 (SOD1) promotes glucose vs lipid metabolism depending on the diet type. We recently reported that nanoformulated SOD1 (Nano) improved lipid metabolism without altering glucose homeostasis in high-fat (HF) diet-fed mice. Here, we sought to determine the effects and potential mechanisms of Nano in modulating glucose and lipid homeostasis in mice fed a normal chow diet (CD) vs HF diet. Mice were fed a CD or a HF diet (45%) for 10 wk and injected with Nano once every 2 days for 15 days. The fasting glucose level was lower (P < 0.05) in CD + Nano-treated mice compared to control. Conversely, blood glucose was not altered but serum triglycerides were lower in HF + Nano-treated mice. Genes involved in fatty acid synthesis were reduced by Nano in the skeletal muscle of CD but not of HF diet-fed mice. Adenosine monophosphate-activated protein kinase (AMPK), which promotes both glucose and lipid metabolism depending on the fuel availability, is activated by Nano in CD-fed mice. Moreover, Nano increased phosphorylation of ACC, a downstream target of AMPK, in both CD and HF diet-fed mice. Nano increased mitochondrial respiration in C2C12 myocytes in the presence of glucose or fatty acid, and this effect is inhibited by Compound C, an AMPK inhibitor. Our data suggest that Nano promotes glucose and lipid metabolism in CD and HF diet-fed mice, respectively, and this effect is mediated partly via AMPK signaling.