High-fat Western Diet Research Articles

Fibronectin Containing Extra Domain A Induces Plaque Destabilization in the Innominate Artery of Aged Apolipoprotein E-Deficient Mice.

Fibronectin containing extra domain A (Fn-EDA) is an endogenous ligand of TLR4 (toll-like receptor 4) and is abundant in the extracellular matrix of advanced atherosclerotic lesions in human and mice. Irrespective of sex, deletion of Fn-EDA reduces early atherosclerosis in apolipoprotein E-deficient (Apoe-/-) mice. However, the contribution of Fn-EDA in advanced atherosclerosis remains poorly characterized. We determined the contribution of Fn-EDA in advanced atherosclerotic lesions of aged (1-year-old) Apoe-/- mice. Plaque composition was determined in the innominate artery, a plaque instability site that is known to mimic several histological features of vulnerable human plaques. Female Apoe-/-, Fn-EDA-/-Apoe-/-, TLR4-/-Apoe-/-, and Fn-EDA-/-TLR4-/-Apoe-/- mice were fed a high-fat Western diet for 44 weeks. Fn-EDA-/-Apoe-/- mice exhibited reduced plaque size characterized by smaller necrotic cores, thick fibrous caps containing abundant vascular smooth muscle cells and collagen, reduced CD68/MMP9 (matrix metalloproteinase 9)-positive content, less accumulation of MMP-cleaved extracellular matrix aggrecan, and decreased vascular smooth muscle cell and macrophage apoptosis (P<0.05 versus Apoe-/- mice). Together these findings suggest that Fn-EDA induces plaque destabilization. Deletion of TLR4 reduced histological features of plaque instability in Apoe-/- mice but did not further reduce features of plaque destabilization in Fn-EDA-/-Apoe-/- mice, suggesting that TLR4 may contribute to Fn-EDA-induced plaque destabilization. Fn-EDA potentiated TLR4-dependent MMP9 expression in bone marrow-derived macrophages, suggesting that macrophage TLR4 may contribute to Fn-EDA-mediated plaque instability. Fn-EDA induces histological features of plaque instability in established lesions of aged Apoe-/- mice. The abundance of Fn-EDA in advanced atherosclerotic lesions may increase the risk of plaque destabilization.

Short-term high-fat diet primes excitatory synapses for long-term depression in orexin neurons.

High-fat diet consumption is a major cause of obesity. Orexin neurons are known to be activated by a high-fat diet and in turn promote further consumption of a high-fat diet. Our study shows that excitatory synapses to orexin neurons become amenable to long-term depression (LTD) after 1week of high-fat diet feeding. However, this effect reverses after 4weeks of a high-fat diet. This LTD may be a homeostatic response to a high-fat diet to curb the activity of orexin neurons and hence caloric consumption. Adaptation seen after prolonged high-fat diet intake may contribute to the development of obesity. Overconsumption of high-fat diets is one of the strongest contributing factors to the rise of obesity rates. Orexin neurons are known to be activated by a palatable high-fat diet and mediate the activation of the mesolimbic reward pathway, resulting in further food intake. While short-term exposure to a high-fat diet is known to induce synaptic plasticity within the mesolimbic pathway, it is unknown if such changes occur in orexin neurons. To investigate this, 3-week-old male rats were fed a palatable high-fat western diet (WD) or control chow for 1week and then invitro patch clamp recording was performed. In the WD condition, an activity-dependent long-term depression (LTD) of excitatory synapses was observed in orexin neurons, but not in chow controls. This LTD was presynaptic and depended on postsynaptic metabotropic glutamate receptor 5 (mGluR5) and retrograde endocannabinoid signalling. WD also increased extracellular glutamate levels, suggesting that glutamate spillover and subsequent activation of perisynaptic mGluR5 may occur more readily in the WD condition. In support of this, pharmacological inhibition of glutamate uptake was sufficient to prime chow control synapses to undergo a presynaptic LTD. Interestingly, these WD effects are transient, as extracellular glutamate levels were similar to controls and LTD was no longer observed in orexin neurons after 4weeks of WD. In summary, excitatory synapses to orexin neurons become amenable to LTD under a palatable high-fat diet, which may represent a homeostatic mechanism to prevent overactivation of these neurons and to curtail high-fat diet consumption.

Colonic aberrant crypt formation accompanies an increase of opportunistic pathogenic bacteria in C57BL/6 mice fed a high-fat diet

The increasing worldwide incidence of colon cancer has been linked to obesity and consumption of a high-fat Western diet. To test the hypothesis that a high-fat diet (HFD) promotes colonic aberrant crypt (AC) formation in a manner associated with gut bacterial dysbiosis, we examined the susceptibility to azoxymethane (AOM)-induced colonic AC and microbiome composition in C57/BL6 mice fed a modified AIN93G diet (AIN, 16% fat, energy) or an HFD (45% fat, energy) for 14 weeks. Mice receiving the HFD exhibited increased plasma leptin, body weight, body fat composition and inflammatory cell infiltration in the ileum compared with those in the AIN group. Consistent with the gut inflammatory phenotype, we observed an increase in colonic AC, plasma interleukin-6, tumor necrosis factor-α, monocyte chemoattractant protein-1 and inducible nitric oxide synthase in the ileum of the HFD-AOM group compared with the AIN-AOM group. Although the HFD and AIN groups did not differ in bacterial species number, the HFD and AIN diets resulted in different bacterial community structures in the colon. The abundance of certain short-chain fatty acid (SCFA) producing bacteria (e.g., Barnesiella) and fecal SCFA (e.g., acetic acid) content were lower in the HFD-AOM group compared with the AIN and AIN-AOM groups. Furthermore, we identified a high abundance of Anaeroplasma bacteria, an opportunistic pathogen in the HFD-AOM group. Collectively, we demonstrate that an HFD promotes AC formation concurrent with an increase of opportunistic pathogenic bacteria in the colon of C57BL/6 mice.

Red raspberries suppress NLRP3 inflammasome and attenuate metabolic abnormalities in diet-induced obese mice

The NLR family pyrin domain containing 3 (NLRP3) inflammasome plays a critical role in insulin resistance and the pathogenesis of type 2 diabetes. Red raspberry (RB) contains high amounts of dietary fibers and polyphenolic compounds, which are known for their anti-oxidative and anti-inflammatory effects. This study evaluated the preventive effects of RB supplementation on the NLRP3 inflammasome activation and associated metabolic abnormalities induced by high fat diet (HFD). Wild-type male mice (six weeks old) were randomized into 4 groups receiving a control or typical western HFD supplemented with or without 5% freeze-dried RB for 12 weeks, when mice were sacrificed for tissue collection. HFD feeding substantially increased body weight, which was alleviated by RB supplementation towards the end of the feeding trial. Dietary RB restored the baseline blood glucose level, ameliorating glucose intolerance and insulin resistance, which were aggravated by HFD. Additionally, HFD reduced O2 expenditure and CO2 production, which were ameliorated by RB consumption. The liver is the key site for energy metabolism and a key peripheral tissue responsive to insulin. RB supplementation reduced hepatic lipid accumulation in HFD mice. In agreement, RB consumption suppressed hepatic NLRP3 inflammasome activation and reduced interleukin (IL)-1β and IL-18 production in HFD mice, accompanied with normalized mitochondriogenesis. These results suggest that RB consumption improves insulin resistance and metabolic dysfunction in diet-induced obesity, which is concomitant with suppression of NLRP3 inflammasome elicited by HFD. Thus, dietary RB intake is a promising strategy for ameliorating diet-induced metabolic abnormalities.

Dietary fat modulation of hepatic lipase variant -514 C/T for lipids: a crossover randomized dietary intervention trial in Caribbean Hispanics.

The hepatic lipase (LIPC) locus is a well-established determinant of high-density lipoprotein cholesterol (HDL-C) concentrations, an association that is modified by dietary fat in observational studies. Dietary interventions are lacking. We investigated dietary modulation of LIPC rs1800588 (-514 C/T) for lipids and glucose using a randomized crossover design comparing a high-fat Western diet and a low-fat traditional Hispanic diet in individuals of Caribbean Hispanic descent (n = 42, 4 wk/phase). No significant gene-diet interactions were observed for HDL-C. However, differences in dietary response according to LIPC genotype were observed. In major allele carriers (CC/CT), HDL-C (mmol/l) was higher following the Western diet compared with the Hispanic diet: phase 1 (Western: 1.3 ± 0.03; Hispanic: 1.1 ± 0.04; P = 0.0004); phase 2 (Western: 1.4 ± 0.03; Hispanic: 1.2 ± 0.03; P = 0.0003). In contrast, HDL-C in TT individuals did not differ by diet. Only major allele carriers benefited from the higher-fat diet for HDL-C. Secondarily, we explored dietary fat quality and rs1800588 for HDL-C and triglycerides (TG) in a Boston Puerto Rican Health Study (BPRHS) subset matched for diabetes and obesity status (subset n = 384). In the BPRHS, saturated fat was unfavorably associated with HDL-C and TG in rs1800588 TT carriers. LIPC rs1800588 appears to modify plasma lipids in the context of dietary fat. This new evidence of genetic modulation of dietary responses may inform optimal and personalized dietary fat advice and reinforces the importance of studying genetic markers in diet and cardiometabolic health.

Abstract LB-213: Thrombospondin-1 regulates intestinal microbiota and bile acid metabolism in a murine model of colorectal cancer

Abstract Colon cancer is major public health concern with over 50,000 deaths annually in the US. Environmental and genetic factors influence colon cancer progression, and expression of thrombospondin-1 (TSP1) inversely correlates with colon cancer aggressiveness. TSP1 is a matricellular protein that regulates vascular physiology and tissue responses to stress. We previously demonstrated that deleting the TSP1 (Thbs1) gene in ApcMin/+ mice results in systemic metabolic changes as assessed in liver tissue, increased tumorigenesis, and lower survival of mice fed a low fat diet. We now show that TSP1 induces changes in intestinal microbiota that may cause shifts in secondary bile acid metabolism that influence colon carcinogenesis. Mice were maintained and bred at least two generations on a low fat western diet to equalize dietary effects on their epigenetic context and microbiomes. Mice were pair-fed a low fat or a 21% high-fat western diet beginning at weaning. Mouse fecal matter was collected 8 weeks after dietary exposures and subjected to 16S sequencing for bacterial population identification. Lactobacillaceae, Lachnopiraceae, Ruminococcacea, Verrucomicrobiaceae families were present in all groups. The family Verrucomicrobiaceae and its genus Akkemensi represented a high proportion of the bacterial population. The relative levels of Akkemensia were elevated in low fat fed mice in mice ApcMin/+ and Thbs1−/−:ApcMin/+ when compared to WT counterparts. Interestingly Akkenmensia abundance was reduced in ApcMin/+ mice fed a high-fat diet when compared to other groups. The relative population of the genus Ruminococcus was reduced in Thbs1−/− mice as well as in Thbs1−/−:ApcMin/+ mice fed low and high fat diets, suggesting that these population shifts are driven by genotype. Because intestinal bacteria can alter metabolism, particularly of bile acids, we collected large intestine tissue from mice and subjected it to metabolomics analysis. Our data showed primary and secondary bile metabolism were regulated by the absence of TSP1 in mice fed a high fat diet when compared to WT. High 6-beta-hydroxylithocholate levels were associated with onset of carcinogenesis since it was elevated in ApcMin/+ and Thbs1−/−:ApcMin/+ mice but not in WT or Thbs1−/−. 6-oxolithocholate, hyocholate and hyodeoxycholate were elevated only in ApcMin/+ mice fed a high fat diet but not in Thbs1−/−:ApcMin/+, suggesting that these metabolites contribute to the shift in survival and carcinogenesis observed between low and high fat diets. On the other hand levels of taurohyodeoxycholic acid, 3-dehydrocholate, 7-ketodeoxycholate were elevated in Thbs1−/−:ApcMin/+ and Thbs1−/− mice but not in ApcMin/+, indicating that changes in these metabolites are driven by the loss of Thbs1 and may pre-dispose mice to increased carcinogenesis when fed a high fat diet. Taken together our data shows an unexpected role of TSP1 in regulation of microbiota and bile acid metabolism and reveals potential targets for prevention and treatment of colorectal cancer. Citation Format: David R. Soto-Pantoja, John M. Sipes, Brian Westwood, Nicole Morris, Nancy J. Emenaker, David D. Roberts. Thrombospondin-1 regulates intestinal microbiota and bile acid metabolism in a murine model of colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-213. doi:10.1158/1538-7445.AM2017-LB-213

Doxorubicin effect is enhanced by sphingosine-1-phosphate signaling antagonist in breast cancer

BackgroundDoxorubicin is one of the most commonly used chemotherapeutic drugs for breast cancer; however, its use is limited by drug resistance and side effects. We hypothesized that adding FTY720, a sphingosine-1-phosphate (S1P) receptor functional antagonist, to doxorubicin would potentiate its effects by suppression of drug-induced inflammation. Materials and MethodsThe Cancer Genome Atlas, Gene Expression Omnibus data sets, and National Cancer Institute-60 panel were used for gene expressions and gene set enrichment analysis. E0771 syngeneic mammary tumor cells were used. OB/OB mice fed with western high-fat diet were used as an obesity model. ResultsSTAT3 expression was significantly increased after doxorubicin treatment in human breast cancer that implicates that doxorubicin evokes inflammation. Expression of sphingosine kinase 1, the enzyme that produces S1P and links inflammation and cancer, tended to be higher in doxorubicin-resistant human cancer and cell lines. In a murine breast cancer model, sphingosine kinase 1, S1P receptor 1, interleukin 6, and STAT3 were overexpressed in the doxorubicin-treated group, whereas all of them were significantly suppressed with addition of FTY720. Combination therapy synergistically suppressed cancer growth both in vitro and in vivo. Furthermore, combination therapy showed higher efficacy in an obesity breast cancer model, where high body mass index demonstrated trends toward worse disease-free and overall survival, and high-serum S1P levels in human patients and volunteers. ConclusionsWe found that FTY720 enhanced the efficacy of doxorubicin by suppression of drug-induced inflammation, and combination therapy showed stronger effect in obesity-related breast cancer.

The effects of fatty acid composition on cardiac hypertrophy and function in mouse models of diet-induced obesity

High-fat diets (HFDs) are used frequently to study the development of cardiac dysfunction in animal models of obesity and diabetes. However, impairment in systolic function, often reported as declining ejection fraction, may not consistently occur in a given time frame which could be contributable to a variety of factors within the experimental design. One major factor may be the amounts of saturated and unsaturated fatty acids (FAs) that are present in the diet. To determine whether the FA content and composition were critical determinants in the development of cardiac dysfunction in response to high-fat feeding, we fed adult, male mice Western diet (45% fat, 60% saturated), Surwit diet (60% fat, 90% saturated), milk-fat-based diet (60% fat, 60% saturated) or high-fat Western diet (HFWD, 60% fat, 32% saturated) for 12 weeks. We report that neither the amount of total fat nor the ratio of saturated to unsaturated FAs in the diets differentially affects body weight and adiposity in mice. In addition, no evidence of systolic dysfunction is present after 12 weeks. Interestingly, the HFWD, with equal parts saturated, monounsaturated and polyunsaturated FAs, induces mild cardiac hypertrophy and diastolic dysfunction after 12 weeks, which coincides with elevated serum levels of arachidonic acid. Our results suggest that the dietary FA content and composition may be a primary determinant of diastolic, but not systolic, dysfunction in animal models of diet-induced obesity.

Abstract 406: Flavocoxid a Dual Cox/Lox Inhibitor Reduces Atherosclerosis Development in ApoE KO Mice Fed With a Western High Fat Diet

Flavocoxid is composed by two flavonoids, baicalin and catechin and it exerts anti-inflammatory effect blocking the peroxidase activity of COX1/2 and 5-LOX. This balanced inhibition prevents the development of adverse effects as demonstrated in clinical trials. The antinflammatory effect of flavocoxid was tested in ApoE knock out mice fed with a high fat western diet. Mice (of both sex) were 5 weeks old at the beginning of the experiment and were fed with a high fat diet for 8 weeks. Mice were randomized to receive: vehicle, or simvastatin (40mg/kg/day by oral suspension), or flavocoxid by oral suspension at the human equivalent dose of 500 mg/day (20mg/kg/day) that was previously reported effective in other inflammatory conditions. The body weight, food intake, cholesterol, and triglyceride levels were recorded every week and at the time of sacrifice the thoracic aorta, liver, and blood samples were taken. Flavocoxid supplementation reduced blood levels of triglycerides and cholesterol and the extent of atherosclerotic plaques. In liver samples the mRNA expression of PPAR-alpha and SREBP-1 was significantly affected by flavocoxid supplementation (p less than 0.05 vs untreated ApoE mice), and the western blot analysis demonstrated an increased expression of the AMPK-alpha kinase demonstrating increased cellular metabolism in treated animals (p less than 0.05 vs untreated ApoE mice). The positive results obtained in this pre-clinical model further support the use of flavocoxid to reduce the atherosclerotic burden.

Exercise Training Rescues High Fat Diet-induced Neuronal Nitric Oxide Synthase Expression In Hippocampus And Cortex

Western high-fat diet (HFD) consumption and being overweight induce hippocampal atrophy and deterioration of function. These alterations are associated with mental disorders, such as depression and anxiety. Exercise is an effective therapeutic treatment to combat obesity and enhance brain health. Numerous studies have demonstrated that neuronal nitric oxide synthase (nNOS) is a key regulator of affective behavior. Increased nNOS expression leads to anxiety, while reduced brain nNOS in an enriched environment that includes running exercise has anxiolytic effects. PURPOSE: We investigated whether HFD consumption and exercise training altered nNOS expression in the brain. METHODS: Twenty 4-week-old male C57BL/6J mice were used. After 2 weeks of acclimatization, mice were randomly assigned to a standard diet (SD; n = 5) or HFD group (n = 15). After 6 weeks, HFD-fed mice were further divided into either a non-exercise (HFD; n = 7) or a HFD (12 weeks) with exercise group (HFD+Ex; n = 8). The HFD+Ex group was allowed free access to a running wheel. Western blotting was performed to determine nNOS protein expression levels in the hippocampus (Hp), cortex (Cx) and cerebellum (Ce) from SD, HFD and HFD+Ex mice. RESULTS: Body weights were significantly increased in HFD-fed mice (SD: 26.0 ± 0.4 g; HFD: 36.6 ± 1.5 g; HFD+Ex: 29.1 ± 0.5 g; p < 0.01). Similarly, mesenteric fat weights were increased in the HFD group, while exercise training mitigated this effect (SD: 0.16 ± 0.04 g; HFD: 0.56 ± 0.10; HFD+Ex: 0.25 ± 0.03; p < 0.01). Compared with that of SD mice, Hp and Cx nNOS expression levels increased significantly with HFD feeding (Hp: 1.90 ± 0.28 fold increase, p < 0.05; Cx: 1.89 ± 0.49; p < 0.01). HFD-induced Hp and Cx nNOS expression was reduced in HFD+Ex mice to levels comparable to those of the SD group, though the difference in the Cx was not significant (Hp: 0.86 ± 0.16 fold increase, Cx: 1.48 ± 0.22; p = 0.1003). While Hp and Cx nNOS expression levels were susceptible to HFD consumption and exercise, those in the Ce were unchanged (p > 0.05). CONCLUSION: We conclude that exercise training restores HFD-induced nNOS expression in the Hp and Cx. Our results indicate that HFD-induced brain dysfunction is regulated by nNOS in the Hp and Cx, and exercise has therapeutic potential for mitigating HFD-induced depression and anxiety via the nNOS/NO pathway.

Investigating modulation of inflammation in atherosclerosis by complement protein C1q

Abstract Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of fatty streaks within arterial walls. In hyperlipidemic conditions, cholesterol accumulates in macrophages disrupting cholesterol trafficking and leading to an inflammatory environment. C1q plays a dual role in atherosclerosis. Activation of complement by C1q exacerbates disease by release of pro-inflammatory activation fragments C3a and C5a. However, we have shown in vitro that C1q has numerous protective roles in atherosclerosis such as improving macrophage cholesterol ingestion and efflux, and polarizing macrophages towards a resolving, anti-inflammatory phenotype. Here we investigate if C1q programs similar macrophage inflammatory responses in vivo. We hypothesize that C1q polarizes macrophages to a protective phenotype in the early stages of atherosclerosis by increasing anti-inflammatory cytokines and decreasing pro-inflammatory cytokines, leading to a reduction in disease markers such as cholesterol and triglyceride levels and atherosclerotic lesion size. To investigate, atherosclerosis model, LDLr−/−, mice that are C1q sufficient or deficient were fed a high fat Western diet for 12 weeks. Changes in plasma cyto/chemokine levels are measured by luminex multiplex assay. Cholesterol and triglyceride levels are measured by colorimetric assay. Atherosclerotic lesions are measured in H&amp;E stained aortic sinus. Preliminary data suggests that C1q modulates disease markers as predicted. By understanding the role of C1q in atherosclerosis it may be possible to design improved treatment strategies.

Insights from engraftable immunodeficient mouse models of hyperinsulinaemia

Hyperinsulinaemia, obesity and dyslipidaemia are independent and collective risk factors for many cancers. Here, the long-term effects of a 23% Western high-fat diet (HFD) in two immunodeficient mouse strains (NOD/SCID and Rag1−/−) suitable for engraftment with human-derived tissue xenografts, and the effect of diet-induced hyperinsulinaemia on human prostate cancer cell line xenograft growth, were investigated. Rag1−/−and NOD/SCID HFD-fed mice demonstrated diet-induced impairments in glucose tolerance at 16 and 23 weeks post weaning. Rag1−/− mice developed significantly higher fasting insulin levels (2.16 ± 1.01 ng/ml, P = 0.01) and increased insulin resistance (6.70 ± 1.68 HOMA-IR, P = 0.01) compared to low-fat chow-fed mice (0.71 ± 0.12 ng/ml and 2.91 ± 0.42 HOMA-IR). This was not observed in the NOD/SCID strain. Hepatic steatosis was more extensive in Rag1−/− HFD-fed mice compared to NOD/SCID mice. Intramyocellular lipid storage was increased in Rag1−/− HFD-fed mice, but not in NOD/SCID mice. In Rag1−/− HFD-fed mice, LNCaP xenograft tumours grew more rapidly compared to low-fat chow-fed mice. This is the first characterisation of the metabolic effects of long-term Western HFD in two mouse strains suitable for xenograft studies. We conclude that Rag1−/− mice are an appropriate and novel xenograft model for studying the relationship between cancer and hyperinsulinaemia.

Dietary α-cyclodextrin reduces atherosclerosis and modifies gut flora in apolipoprotein E-deficient mice.

α-Cyclodextrin (α-CD), a cyclic polymer of glucose, has been shown to lower plasma cholesterol in animals and humans; however, its effect on atherosclerosis has not been previously described. apoE-knockout mice were fed either low-fat diet (LFD; 5.2% fat, w/w), or Western high fat diet (21.2% fat) containing either no additions (WD), 1.5% α-CD (WDA); 1.5% β-CD (WDB); or 1.5% oligofructose-enriched inulin (WDI). Although plasma lipids were similar after 11 weeks on the WD vs. WDA diets, aortic atherosclerotic lesions were 65% less in mice on WDA compared to WD (P < 0.05), and similar to mice fed the LFD. No effect on atherosclerosis was observed for the other WD supplemented diets. By RNA-seq analysis of 16S rRNA, addition of α-CD to the WD resulted in significantly decreased cecal bacterial counts in genera Clostridium and Turicibacterium, and significantly increased Dehalobacteriaceae. At family level, Comamonadaceae significantly increased and Peptostreptococcaceae showed a negative trend. Several of these bacterial count changes correlated negatively with % atherosclerotic lesion and were associated with increased cecum weight and decreased plasma cholesterol levels. Addition of α-CD to the diet of apoE-knockout mice decreases atherosclerosis and is associated with changes in the gut flora.

Alterations in Gut Microbiota and Immunity by Dietary Fat.

Gut microbiota play critical physiological roles in energy extraction from the intestine and in the control of systemic immunity, as well as local intestinal immunity. Disturbance of gut microbiota leads to the development of several diseases, such as colitis, inflammatory bowel diseases, metabolic disorders, cancer, etc. From a metabolic point of view, the gut is a large metabolic organ and one of the first to come into contact with dietary fats. Interestingly, excessive dietary fat has been incriminated as a primary culprit of metabolic syndrome and obesity. After intake of high-fat diet or Western diet, extensive changes in gut microbiota have been observed, which may be an underlying cause of alterations in whole body metabolism and nutrient homeostasis. Here, we summarize recent data on changes in the gut microbiota and immunity associated with dietary fat, as well as their relationships with the pathogenesis of metabolic syndrome. These findings may provide insight into the understanding of the complex pathophysiology related to the development of metabolic diseases and offer an opportunity to develop novel candidates for therapeutic agents.

Intrauterine growth restriction influences vascular remodeling and stiffening in the weanling rat more than sex or diet.

We report intrauterine growth restriction (IUGR) increases vascular stiffening in both male and female rats through increased collagen content and altered elastin structure more than a high-fat diet (HFD) alone. Our study shows the importance of stiffness supporting the hypothesis that there are physiologic differences and potential windows for early intervention targeting vascular remodeling mechanisms.

206 - Chronic Ethanol Consumption Alters SOD2 Dynamics through Lysine Acetylation

Chronic ethanol consumption is a significant source of morbidity and mortality worldwide and contributes to approximately 6% of global deaths. Understanding mechanisms of hepatic mitochondrial dysfunction resulting from ethanol metabolism remains a key area of interest. Our findings demonstrate that liver physiology is altered by ethanol-induced mitochondrial protein hyperacetylation. Since oxidative stress is a critical marker of early-stage ethanol toxicity in the liver, scrutiny is focused on the impact of ethanol toxicity on the acetylation status of mitochondrial antioxidant proteins and overall antioxidant status. We used a mouse model that employs a Lieber-DeCarli liquid diet to examine the impact of chronic ethanol consumption in a high-fat Western diet. Towards the goal of elucidating mechanisms of alcohol toxicity, we integrated a multi-omics approach utilizing techniques such as 1D- and 2D-SDS-PAGE followed by Western blot, immunohistochemistry (IHC), enzyme activity assays, quantitative acetylomics via HPLC-MS/MS, and computational modeling. These proteomic techniques were employed to assess changes in the acetylation status of individual lysine residues on mitochondrial antioxidant proteins from control and ethanol-fed mice. The results of our studies indicate that, as a result of chronic ethanol consumption, the global acetylation of SOD2 lysine residues was increased in liver by 270% and 400%, as quantified by Western blot and LC-MS/MS, respectively. Western blot analysis also showed an approximate 400% increase in SOD2 K68 acetylation, which is known to inhibit enzyme activity. IHC analysis revealed that ethanol-induced acetylation of SOD2-K68 is significantly increased in the zone 3 in liver, which is generally known to be hypoxic. Our findings also correlate with a decreased ratio of GSH/GSSG as a consequence of ethanol toxicity. These acetyl-related changes were then correlated with alterations in SOD2 enzymatic structure and activity. Interestingly, chronic ethanol consumption shifted the isoelectric point of SOD2 toward a more negative state as demonstrated by 2D- electrophoresis. Ethanol-induced acetylation in vivo also decreased SOD2 activity by 40%. Through the integration of enzyme assays, mass spectrometry, and computational biology, our goal is to further elucidate mechanisms of nutrient disruption and oxidative stress due to alcohol toxicity.

High-fat Western diet–induced obesity contributes to increased tumor growth in mouse models of human colon cancer

Strong epidemiologic evidence links colon cancer to obesity. The increasing worldwide incidence of colon cancer has been linked to the spread of the Western lifestyle, and in particular consumption of a high-fat Western diet. In this study, our objectives were to establish mouse models to examine the effects of high-fat Western diet–induced obesity on the growth of human colon cancer tumor xenografts, and to examine potential mechanisms driving obesity-linked human colon cancer tumor growth. We hypothesize that mice rendered insulin resistant due to consumption of a high-fat Western diet will show increased and accelerated tumor growth. Homozygous Rag1tm1Mom mice were fed either a low-fat Western diet or a high-fat Western diet (HFWD), then human colon cancer xenografts were implanted subcutaneously or orthotopically. Tumors were analyzed to detect changes in receptor tyrosine kinase–mediated signaling and expression of inflammatory-associated genes in epididymal white adipose tissue. In both models, mice fed an HFWD weighed more and had increased intra-abdominal fat, and tumor weight was greater compared with in the low-fat Western diet–fed mice. They also displayed significantly higher levels of leptin; however, there was a negative correlation between leptin levels and tumor size. In the orthotopic model, tumors and adipose tissue from the HFWD group displayed significant increases in both c-Jun N-terminal kinase activation and monocyte chemoattractant protein 1 expression, respectively. In conclusion, this study suggests that human colon cancer growth is accelerated in animals that are obese and insulin resistant due to the consumption of an HFWD.

Western High-Fat Diet Consumption during Adolescence Increases Susceptibility to Traumatic Stress while Selectively Disrupting Hippocampal and Ventricular Volumes.

Psychological trauma and obesity co-occur frequently and have been identified as major risk factors for psychiatric disorders. Surprisingly, preclinical studies examining how obesity disrupts the ability of the brain to cope with psychological trauma are lacking. The objective of this study was to determine whether an obesogenic Western-like high-fat diet (WD) predisposes rats to post-traumatic stress responsivity. Adolescent Lewis rats (postnatal day 28) were fed ad libitum for 8 weeks with either the experimental WD diet (41.4% kcal from fat) or the control diet (16.5% kcal from fat). We modeled psychological trauma by exposing young adult rats to a cat odor threat. The elevated plus maze and the open field test revealed increased psychological trauma-induced anxiety-like behaviors in the rats that consumed the WD when compared with control animals 1 week after undergoing traumatic stress (p < 0.05). Magnetic resonance imaging showed significant hippocampal atrophy (20% reduction) and lateral ventricular enlargement (50% increase) in the animals fed the WD when compared with controls. These volumetric abnormalities were associated with behavioral indices of anxiety, increased leptin and FK506-binding protein 51 (FKBP51) levels, and reduced hippocampal blood vessel density. We found asymmetric structural vulnerabilities to the WD, particularly the ventral and left hippocampus and lateral ventricle. This study highlights how WD consumption during adolescence impacts key substrates implicated in post-traumatic stress disorder. Understanding how consumption of a WD affects the developmental trajectories of the stress neurocircuitry is critical, as stress susceptibility imposes a marked vulnerability to neuropsychiatric disorders.

Estrogen receptor alpha activation enhances mitochondrial function and systemic metabolism in high-fat-fed ovariectomized mice.

Estrogen impacts insulin action and cardiac metabolism, and menopause dramatically increases cardiometabolic risk in women. However, the mechanism(s) of cardiometabolic protection by estrogen remain incompletely understood. Here, we tested the effects of selective activation of E2 receptor alpha (ER α) on systemic metabolism, insulin action, and cardiac mitochondrial function in a mouse model of metabolic dysfunction (ovariectomy [OVX], insulin resistance, hyperlipidemia, and advanced age). Middle‐aged (12‐month‐old) female low‐density lipoprotein receptor (Ldlr)−/− mice were subjected to OVX or sham surgery and fed “western” high‐fat diet (WHFD) for 3 months. Selective ER α activation with 4,4′,4″‐(4‐Propyl‐[1H]‐pyrazole‐1,3,5‐triyl) (PPT), prevented weight gain, improved insulin action, and reduced visceral fat accumulation in WHFD‐fed OVX mice. PPT treatment also elevated systemic metabolism, increasing oxygen consumption and core body temperature, induced expression of several metabolic genes such as peroxisome proliferator‐activated receptor gamma, coactivator 1 alpha, and nuclear respiratory factor 1 in heart, liver, skeletal muscle, and adipose tissue, and increased cardiac mitochondrial function. Taken together, selective activation of ER α with PPT enhances metabolic effects including insulin resistance, whole body energy metabolism, and mitochondrial function in OVX mice with metabolic syndrome.

Loss of Transcription Factor CREBH Accelerates Diet-Induced Atherosclerosis in Ldlr-/- Mice.

Liver-enriched transcription factor cAMP-responsive element-binding protein H (CREBH) regulates plasma triglyceride clearance by inducing lipoprotein lipase cofactors, such as apolipoprotein A-IV (apoA-IV), apoA-V, and apoC-II. CREBH also regulates apoA-I transcription. This study aims to determine whether CREBH has a role in lipoprotein metabolism and development of atherosclerosis. CREBH-deficient Creb3l3(-/-) mice were bred with Ldlr(-/-) mice creating Ldlr(-/-) Creb3l3(-/-) double knockout mice. Mice were fed on a high-fat and high-sucrose Western diet for 20 weeks. We showed that CREBH deletion in Ldlr(-/-) mice increased very low-density lipoprotein-associated triglyceride and cholesterol levels, consistent with the impairment of lipoprotein lipase-mediated triglyceride clearance in these mice. In contrast, high-density lipoprotein cholesterol levels were decreased in CREBH-deficient mice, which was associated with decreased production of apoA-I from the liver. The results indicate that CREBH directly activated Apoa1 gene transcription. Accompanied by the worsened atherogenic lipid profile, Ldlr(-/-) Creb3l3(-/-) mice developed significantly more atherosclerotic lesions in the aortas than Ldlr(-/-) mice. We identified CREBH as an important regulator of lipoprotein metabolism and suggest that increasing hepatic CREBH activity may be a novel strategy for prevention and treatment of atherosclerosis.