Fasted Sprint Interval Training Results in Some Beneficial Skeletal Muscle Metabolic, but Similar Metabolomic and Performance Adaptations Compared With Carbohydrate-Fed Training in Recreationally Active Male.

Endurance training in fasted conditions (FAST) induces favorable skeletal muscle metabolic adaptations compared with carbohydrate feeding (CHO), manifesting in improved exercise performance over time. Sprint interval training (SIT) is a potent metabolic stimulus, however nutritional strategies to optimize adaptations to SIT are poorly characterized. Here we investigated the efficacy of FAST versus CHO SIT (4-6 × 30-s Wingate sprints interspersed with 4-min rest) on muscle metabolic, serum metabolome and exercise performance adaptations in a double-blind parallel group design in recreationally active males. Following acute SIT, we observed exercise-induced increases in pan-acetylation and several genes associated with mitochondrial biogenesis, fatty acid oxidation, and NAD+-biosynthesis, along with favorable regulation of PDK4 (p = .004), NAMPT (p = .0013), and NNMT (p = .001) in FAST. Following 3 weeks of SIT, NRF2 (p = .029) was favorably regulated in FAST, with augmented pan-acetylation in CHO but not FAST (p = .033). SIT induced increases in maximal citrate synthase activity were evident with no effect of nutrition, while 3-hydroxyacyl-CoA dehydrogenase activity did not change. Despite no difference in the overall serum metabolome, training-induced changes in C3:1 (p = .013) and C4:1 (p = .010) which increased in FAST, and C16:1 (p = .046) and glutamine (p = .021) which increased in CHO, were different between groups. Training-induced increases in anaerobic (p = .898) and aerobic power (p = .249) were not influenced by nutrition. These findings suggest some beneficial muscle metabolic adaptations are evident in FAST versus CHO SIT following acute exercise and 3 weeks of SIT. However, this stimulus did not manifest in differential exercise performance adaptations.

Divergent serum metabolomic, skeletal muscle signaling, transcriptomic, and performance adaptations to fasted versus whey protein-fed sprint interval training.

Sprint interval training (SIT) is a time-efficient alternative to endurance exercise, conferring beneficial skeletal muscle metabolic adaptations. Current literature has investigated the nutritional regulation of acute and chronic exercise-induced metabolic adaptations in muscle following endurance exercise, principally comparing the impact of training in fasted and carbohydrate-fed (CHO) conditions. Alternative strategies such as exercising in low CHO, protein-fed conditions remain poorly characterized, specifically pertaining to adaptations associated with SIT. Thus, this study aimed to compare the metabolic and performance adaptations to acute and short-term SIT in the fasted state with preexercise hydrolyzed (WPH) or concentrated (WPC) whey protein supplementation. In healthy males, preexercise protein ingestion did not alter exercise-induced increases in PGC-1α, PDK4, SIRT1, and PPAR-δ mRNA expression following acute SIT. However, supplementation of WPH beneficially altered acute exercise-induced CD36 mRNA expression. Preexercise protein ingestion attenuated acute exercise-induced increases in muscle pan-acetylation and PARP1 protein content compared with fasted SIT. Acute serum metabolomic differences confirmed greater preexercise amino acid delivery in protein-fed compared with fasted conditions. Following 3 wk of SIT, training-induced increases in mitochondrial enzymatic activity and exercise performance were similar across nutritional groups. Interestingly, resting muscle acetylation status was downregulated in WPH conditions following training. Such findings suggest preexercise WPC and WPH ingestion positively influences metabolic adaptations to SIT compared with fasted training, resulting in either similar or enhanced performance adaptations. Future studies investigating nutritional modulation of metabolic adaptations to exercise are warranted to build upon these novel findings.NEW & NOTEWORTHY These are the first data to show the influence of preexercise protein on serum and skeletal muscle metabolic adaptations to acute and short-term sprint interval training (SIT). Preexercise whey protein concentrate (WPC) or hydrolysate (WPH) feeding acutely affected the serum metabolome, which differentially influenced acute and chronic changes in mitochondrial gene expression, intracellular signaling (acetylation and PARylation) resulting in either similar or enhanced performance outcomes when compared with fasted training.

Development of a multiplex assay to determine the expression of mitochondrial genes in human skeletal muscle.

NEW FINDINGS: What is the central question of this study? Can a custom-designed multiplex gene expression assay be used to quantify expression levels of a targeted group of mitochondrial genes in human skeletal muscle? What is the main finding and its importance? A custom-designed GeXP multiplex assay was developed, and the ability to accurately quantify expression of a targeted set of mitochondrial genes in human skeletal muscle was demonstrated. It holds distinct methodological and practical advantages over other commonly used quantification methods. ABSTRACT: Skeletal muscle is an important endocrine tissue demonstrating plasticity in response to external stimuli, including exercise and nutrition. Mitochondrial biogenesis is a common hallmark of adaptations to aerobic exercise training. Furthermore, altered expression of several genes implicated in the regulation of mitochondrial biogenesis, substrate oxidation and nicotinamide adenine dinucleotide (NAD+ ) biosynthesis following acute exercise underpins longer-term muscle metabolic adaptations. Gene expression is typically measured using real-time quantitative PCR platforms. However, interest has developed in the design of multiplex gene expression assays (GeXP) using the GenomeLab GeXP™ genetic analysis system, which can simultaneously quantify gene expression of multiple targets, holding distinct advantages in terms of throughput, limiting technical error, cost effectiveness, and quantifying gene co-expression. This study describes the development of a custom-designed GeXP assay incorporating the measurement of proposed regulators of mitochondrial biogenesis, substrate oxidation, and NAD+ biosynthetic capacity in human skeletal muscle and characterises the resting gene expression (overnight fasted and non-exercised) signature within a group of young, healthy, recreationally active males. The design of GeXP-based assays provides the capacity to more accurately characterise the regulation of a targeted group of genes with specific regulatory functions, a potentially advantageous development for future investigations of the regulation of muscle metabolism by exercise and/or nutrition.

Inter-Individual Variation in Postprandial Glycemic Responses in Women Co-Ingesting Green Leafy Vegetables with a Carbohydrate Meal: Interactions with the Sirtuin System.

SCOPE: Green leafy vegetables (GLV) may improve postprandial glycemic responses (PGR) and metabolic health. However, inter-individual variations (IIV) preclude conclusive evidence. Sirtuin system is emerging as a key player in blood glucose control. This study investigates IIV in PGR in women co-ingesting GLV with a carbohydrate meal and interactions with the sirtuin system. METHODS AND RESULTS: Volunteers (n = 31 women) consume rice, rice with bok choy, or spinach (75g available carbohydrate) on separate occasions. Postprandial glucose, insulin, adropin, and lipid levels are measured. Anthropometric measurements and sex hormones are measured. GeXP assay measures whole blood postprandial gene expression profiles of 25 markers involved in sirtuin signaling. GLV consumption has no significant effect on PGR, which shows high variation. PGR correlated with age, but no other consistent associations are observed. Sirtuin gene expression profiles reveal distinct stratified subgroups associated with PGR, lipid, insulin, fat mass, waist/hip circumferences, and adropin levels. CONCLUSION: PGR to co-ingesting GLV with a carbohydrate meal are highly variable in this cohort and fail to reveal a significant reduction in PGR. Variable responses are largely independent of menopausal status and meal consumed. However, lower expression of sirtuin gene targets is associated with higher PGR and with markers linked to health status.

Challenges of the heterogeneous nutrition response: interpreting the group mean.

Extensive research demonstrates unequivocally that nutrition plays a fundamental role in maintaining health and preventing disease. In parallel nutrition research provides evidence that the risks and benefits of diet and lifestyle choices do not affect people equally, as people are inherently variable in their responses to nutrition and associated interventions to maintain health and prevent disease. To simplify the inherent complexity of human subjects and their nutrition, with the aim of managing expectations for dietary guidance required to ensure healthy populations and individuals, nutrition researchers often seek to group individuals based on commonly used criteria. This strategy relies on demonstrating meaningful conclusions based on comparison of group mean responses of assigned groups. Such studies are often confounded by the heterogeneous nutrition response. Commonly used criteria applied in grouping study populations and individuals to identify mechanisms and determinants of responses to nutrition often contribute to the problem of interpreting the results of group comparisons. Challenges of interpreting the group mean using diverse populations will be discussed with respect to studies in human subjects, in vivo and in vitro model systems. Future advances in nutrition research to tackle inter-individual variation require a coordinated approach from funders, learned societies, nutrition scientists, publishers and reviewers of the scientific literature. This will be essential to develop and implement improved study design, data recording, analysis and reporting to facilitate more insightful interpretation of the group mean with respect to population diversity and the heterogeneous nutrition response.

Palmitic acid triggers inflammatory responses in N42 cultured hypothalamic cells partially via ceramide synthesis but not via TLR4.

A high-fat diet induces hypothalamic inflammation in rodents which, in turn, contributes to the development of obesity by eliciting both insulin and leptin resistance. However, the mechanism by which long-chain saturated fatty acids trigger inflammation is still contentious. To elucidate this mechanism, the effect of fatty acids on the expression of the pro-inflammatory cytokines IL-6 and TNFα was investigated in the mHypoE-N42 hypothalamic cell line (N42). N42 cells were treated with lauric acid (LA) and palmitic acid (PA). PA challenge was carried out in the presence of either a TLR4 inhibitor, a ceramide synthesis inhibitor (L-cycloserine), oleic acid (OA) or eicosapentaenoic acid (EPA). Intracellular ceramide accumulation was quantified using LC-ESI-MS/MS. PA but not LA upregulated IL-6 and TNFα. L-cycloserine, OA and EPA all counteracted PA-induced intracellular ceramide accumulation leading to a downregulation of IL-6 and TNFα. However, a TLR4 inhibitor failed to inhibit PA-induced upregulation of pro-inflammatory cytokines.In conclusion, PA induced the expression of IL-6 and TNFα in N42 neuronal cells independently of TLR4 but, partially, via ceramide synthesis with OA and EPA being anti-inflammatory by decreasing PA-induced intracellular ceramide build-up. Thus, ceramide accumulation represents one on the mechanisms by which PA induces inflammation in neurons.

SerpinA3N is a novel hypothalamic gene upregulated by a high-fat diet and leptin in mice.

BACKGROUND: Energy homeostasis is regulated by the hypothalamus but fails when animals are fed a high-fat diet (HFD), and leptin insensitivity and obesity develops. To elucidate the possible mechanisms underlying these effects, a microarray-based transcriptomics approach was used to identify novel genes regulated by HFD and leptin in the mouse hypothalamus. RESULTS: Mouse global array data identified serpinA3N as a novel gene highly upregulated by both a HFD and leptin challenge. In situ hybridisation showed serpinA3N expression upregulation by HFD and leptin in all major hypothalamic nuclei in agreement with transcriptomic gene expression data. Immunohistochemistry and studies in the hypothalamic clonal neuronal cell line, mHypoE-N42 (N42), confirmed that alpha 1-antichymotrypsin (α1AC), the protein encoded by serpinA3, is localised to neurons and revealed that it is secreted into the media. SerpinA3N expression in N42 neurons is upregulated by palmitic acid and by leptin, together with IL-6 and TNFα, and all three genes are downregulated by the anti-inflammatory monounsaturated fat, oleic acid. Additionally, palmitate upregulation of serpinA3 in N42 neurons is blocked by the NFκB inhibitor, BAY11, and the upregulation of serpinA3N expression in the hypothalamus by HFD is blunted in IL-1 receptor 1 knockout (IL-1R1 -/- ) mice. CONCLUSIONS: These data demonstrate that serpinA3 expression is implicated in nutritionally mediated hypothalamic inflammation.

Dietary fibers inhibit obesity in mice, but host responses in the cecum and liver appear unrelated to fiber-specific changes in cecal bacterial taxonomic composition.

Dietary fibers (DF) can prevent obesity in rodents fed a high-fat diet (HFD). Their mode of action is not fully elucidated, but the gut microbiota have been implicated. This study aimed to identify the effects of seven dietary fibers (barley beta-glucan, apple pectin, inulin, inulin acetate ester, inulin propionate ester, inulin butyrate ester or a combination of inulin propionate ester and inulin butyrate ester) effective in preventing diet-induced obesity and links to differences in cecal bacteria and host gene expression. Mice (n = 12) were fed either a low-fat diet (LFD), HFD or a HFD supplemented with the DFs, barley beta-glucan, apple pectin, inulin, inulin acetate ester, inulin propionate ester, inulin butyrate ester or a combination of inulin propionate ester and inulin butyrate ester for 8 weeks. Cecal bacteria were determined by Illumina MiSeq sequencing of 16S rRNA gene amplicons. Host responses, body composition, metabolic markers and gene transcription (cecum and liver) were assessed post intervention. HFD mice showed increased adiposity, while all of the DFs prevented weight gain. DF specific differences in cecal bacteria were observed. Results indicate that diverse DFs prevent weight gain on a HFD, despite giving rise to different cecal bacteria profiles. Conversely, common host responses to dietary fiber observed are predicted to be important in improving barrier function and genome stability in the gut, maintaining energy homeostasis and reducing HFD induced inflammatory responses in the liver.

Specific substrate-driven changes in human faecal microbiota composition contrast with functional redundancy in short-chain fatty acid production.

The diet provides carbohydrates that are non-digestible in the upper gut and are major carbon and energy sources for the microbial community in the lower intestine, supporting a complex metabolic network. Fermentation produces the short-chain fatty acids (SCFAs) acetate, propionate and butyrate, which have health-promoting effects for the human host. Here we investigated microbial community changes and SCFA production during in vitro batch incubations of 15 different non-digestible carbohydrates, at two initial pH values with faecal microbiota from three different human donors. To investigate temporal stability and reproducibility, a further experiment was performed 1 year later with four of the carbohydrates. The lower pH (5.5) led to higher butyrate and the higher pH (6.5) to more propionate production. The strongest propionigenic effect was found with rhamnose, followed by galactomannans, whereas fructans and several α- and ß-glucans led to higher butyrate production. 16S ribosomal RNA gene-based quantitative PCR analysis of 22 different microbial groups together with 454 sequencing revealed significant stimulation of specific bacteria in response to particular carbohydrates. Some changes were ascribed to metabolite cross-feeding, for example, utilisation by Eubacterium hallii of 1,2-propanediol produced from fermentation of rhamnose by Blautia spp. Despite marked inter-individual differences in microbiota composition, SCFA production was surprisingly reproducible for different carbohydrates, indicating a level of functional redundancy. Interestingly, butyrate formation was influenced not only by the overall % butyrate-producing bacteria in the community but also by the initial pH, consistent with a pH-dependent shift in the stoichiometry of butyrate production.

Inter-individual responses to sprint interval training, a pilot study investigating interactions with the sirtuin system.

Sprint interval training (SIT) is reported to improve blood glucose control and may be a useful public health tool. The sirtuins and associated genes are emerging as key players in blood glucose control. This study investigated the interplay between the sirtuin/NAD system and individual variation in insulin sensitivity responses after SIT in young healthy individuals. Before and after 4 weeks of SIT, body mass and fat percentage were measured and oral glucose tolerance tests performed in 20 young healthy participants (7 females). Blood gene expression profiles (all 7 mammalian sirtuin genes and 15 enzymes involved in conversion of tryptophan, bioavailable vitamin B3, and metabolic precursors to NAD). NAD/NADP was measured in whole blood. Significant reductions in body weight and body fat post-SIT were associated with altered lipid profiles, NAD/NADP, and regulation of components of the sirtuin/NAD system (NAMPT, NMNAT1, CD38, and ABCA1). Variable improvements in measured metabolic health parameters were evident and attributed to different responses in males and females, together with marked inter-individual variation in responses of the sirtuin/NAD system to SIT.

Tissue-specific regulation of sirtuin and nicotinamide adenine dinucleotide biosynthetic pathways identified in C57Bl/6 mice in response to high-fat feeding.

The sirtuin (SIRT)/nicotinamide adenine dinucleotide (NAD) system is implicated in development of type 2 diabetes (T2D) and diet-induced obesity, a major risk factor for T2D. Mechanistic links have not yet been defined. SIRT/NAD system gene expression and NAD/NADH levels were measured in liver, white adipose tissue (WAT) and skeletal muscle from mice fed either a low-fat diet or high-fat diet (HFD) for 3 days up to 16 weeks. An in-house custom-designed multiplex gene expression assay assessed all 7 mouse SIRTs (SIRT1-7) and 16 enzymes involved in conversion of tryptophan, niacin, nicotinamide riboside and metabolic precursors to NAD. Significantly altered transcription was correlated with body weight, fat mass, plasma lipids and hormones. Regulation of the SIRT/NAD system was associated with early (SIRT4, SIRT7, NAPRT1 and NMNAT2) and late phases (NMNAT3, NMRK2, ABCA1 and CD38) of glucose intolerance. TDO2 and NNMT were identified as markers of HFD consumption. Altered regulation of the SIRT/NAD system in response to HFD was prominent in liver compared with WAT or muscle. Multiple components of the SIRTs and NAD biosynthetic enzymes network respond to consumption of dietary fat. Novel molecular targets identified above could direct strategies for dietary/therapeutic interventions to limit metabolic dysfunction and development of T2D.

Molecular Profiling of Multiplexed Gene Markers to Assess Viability of Ex Vivo Human Colon Explant Cultures.

Human colon tissue explant culture provides a physiologically relevant model system to study human gut biology. However, the small (20-30 mg) and complex tissue samples used present challenges for monitoring tissue stability, viability, and provision of sufficient tissue for analyses. Combining molecular profiling with explant culture has potential to overcome such limitations, permitting interrogation of complex gene regulation required to maintain gut mucosa in culture, monitor responses to culture environments and interventions. Human ex vivo colon explant gene expression profiles were assayed using an in-house custom-designed hCellMarkerPlex assay at culture time points 0, 1, 2, 4, and 14 h. Characteristic profiles of epithelial cell markers linked to differentiation, cellular polarization, and apoptosis were correlated with visible histochemical changes in explant epithelium during culture and tissue donors. The GenomeLab System provides effective assay of multiple targets not possible from small tissue samples with conventional gene expression technology platforms. This is advantageous to increase the utility of the ex vivo human colon model in applications to interrogate this complex and dynamic tissue environment for use in analytical testing.

Designing a broad-spectrum integrative approach for cancer prevention and treatment.

Targeted therapies and the consequent adoption of "personalized" oncology have achieved notable successes in some cancers; however, significant problems remain with this approach. Many targeted therapies are highly toxic, costs are extremely high, and most patients experience relapse after a few disease-free months. Relapses arise from genetic heterogeneity in tumors, which harbor therapy-resistant immortalized cells that have adopted alternate and compensatory pathways (i.e., pathways that are not reliant upon the same mechanisms as those which have been targeted). To address these limitations, an international task force of 180 scientists was assembled to explore the concept of a low-toxicity "broad-spectrum" therapeutic approach that could simultaneously target many key pathways and mechanisms. Using cancer hallmark phenotypes and the tumor microenvironment to account for the various aspects of relevant cancer biology, interdisciplinary teams reviewed each hallmark area and nominated a wide range of high-priority targets (74 in total) that could be modified to improve patient outcomes. For these targets, corresponding low-toxicity therapeutic approaches were then suggested, many of which were phytochemicals. Proposed actions on each target and all of the approaches were further reviewed for known effects on other hallmark areas and the tumor microenvironment. Potential contrary or procarcinogenic effects were found for 3.9% of the relationships between targets and hallmarks, and mixed evidence of complementary and contrary relationships was found for 7.1%. Approximately 67% of the relationships revealed potentially complementary effects, and the remainder had no known relationship. Among the approaches, 1.1% had contrary, 2.8% had mixed and 62.1% had complementary relationships. These results suggest that a broad-spectrum approach should be feasible from a safety standpoint. This novel approach has potential to be relatively inexpensive, it should help us address stages and types of cancer that lack conventional treatment, and it may reduce relapse risks. A proposed agenda for future research is offered.

Dysregulated metabolism contributes to oncogenesis.

Cancer is a disease characterized by unrestrained cellular proliferation. In order to sustain growth, cancer cells undergo a complex metabolic rearrangement characterized by changes in metabolic pathways involved in energy production and biosynthetic processes. The relevance of the metabolic transformation of cancer cells has been recently included in the updated version of the review "Hallmarks of Cancer", where dysregulation of cellular metabolism was included as an emerging hallmark. While several lines of evidence suggest that metabolic rewiring is orchestrated by the concerted action of oncogenes and tumor suppressor genes, in some circumstances altered metabolism can play a primary role in oncogenesis. Recently, mutations of cytosolic and mitochondrial enzymes involved in key metabolic pathways have been associated with hereditary and sporadic forms of cancer. Together, these results demonstrate that aberrant metabolism, once seen just as an epiphenomenon of oncogenic reprogramming, plays a key role in oncogenesis with the power to control both genetic and epigenetic events in cells. In this review, we discuss the relationship between metabolism and cancer, as part of a larger effort to identify a broad-spectrum of therapeutic approaches. We focus on major alterations in nutrient metabolism and the emerging link between metabolism and epigenetics. Finally, we discuss potential strategies to manipulate metabolism in cancer and tradeoffs that should be considered. More research on the suite of metabolic alterations in cancer holds the potential to discover novel approaches to treat it.

Predictive gene signatures: molecular markers distinguishing colon adenomatous polyp and carcinoma.

Cancers exhibit abnormal molecular signatures associated with disease initiation and progression. Molecular signatures could improve cancer screening, detection, drug development and selection of appropriate drug therapies for individual patients. Typically only very small amounts of tissue are available from patients for analysis and biopsy samples exhibit broad heterogeneity that cannot be captured using a single marker. This report details application of an in-house custom designed GenomeLab System multiplex gene expression assay, the hCellMarkerPlex, to assess predictive gene signatures of normal, adenomatous polyp and carcinoma colon tissue using archived tissue bank material. The hCellMarkerPlex incorporates twenty-one gene markers: epithelial (EZR, KRT18, NOX1, SLC9A2), proliferation (PCNA, CCND1, MS4A12), differentiation (B4GANLT2, CDX1, CDX2), apoptotic (CASP3, NOX1, NTN1), fibroblast (FSP1, COL1A1), structural (ACTG2, CNN1, DES), gene transcription (HDAC1), stem cell (LGR5), endothelial (VWF) and mucin production (MUC2). Gene signatures distinguished normal, adenomatous polyp and carcinoma. Individual gene targets significantly contributing to molecular tissue types, classifier genes, were further characterised using real-time PCR, in-situ hybridisation and immunohistochemistry revealing aberrant epithelial expression of MS4A12, LGR5 CDX2, NOX1 and SLC9A2 prior to development of carcinoma. Identified gene signatures identify aberrant epithelial expression of genes prior to cancer development using in-house custom designed gene expression multiplex assays. This approach may be used to assist in objective classification of disease initiation, staging, progression and therapeutic responses using biopsy material.

The development of diet-induced obesity and glucose intolerance in C57BL/6 mice on a high-fat diet consists of distinct phases.

High-fat (HF) diet-induced obesity and insulin insensitivity are associated with inflammation, particularly in white adipose tissue (WAT). However, insulin insensitivity is apparent within days of HF feeding when gains in adiposity and changes in markers of inflammation are relatively minor. To investigate further the effects of HF diet, C57Bl/6J mice were fed either a low (LF) or HF diet for 3 days to 16 weeks, or fed the HF-diet matched to the caloric intake of the LF diet (PF) for 3 days or 1 week, with the time course of glucose tolerance and inflammatory gene expression measured in liver, muscle and WAT. HF fed mice gained adiposity and liver lipid steadily over 16 weeks, but developed glucose intolerance, assessed by intraperitoneal glucose tolerance tests (IPGTT), in two phases. The first phase, after 3 days, resulted in a 50% increase in area under the curve (AUC) for HF and PF mice, which improved to 30% after 1 week and remained stable until 12 weeks. Between 12 and 16 weeks the difference in AUC increased to 60%, when gene markers of inflammation appeared in WAT and muscle but not in liver. Plasma proteomics were used to reveal an acute phase response at day 3. Data from PF mice reveals that glucose intolerance and the acute phase response are the result of the HF composition of the diet and increased caloric intake respectively. Thus, the initial increase in glucose intolerance due to a HF diet occurs concurrently with an acute phase response but these effects are caused by different properties of the diet. The second increase in glucose intolerance occurs between 12-16 weeks of HF diet and is correlated with WAT and muscle inflammation. Between these times glucose tolerance remains stable and markers of inflammation are undetectable.

Postprandial cell defense system responses to meal formulations: stratification through gene expression profiling.

SCOPE: Cell defenses regulating homeostatic control of postprandial stress are influenced by interindividual variation, food composition and health status. This study investigates effects of food composition on individual postprandial responses and associations with health. METHODS AND RESULTS: Volunteers (n = 16) consumed four food formulations (50% unsaturated/saturated fat, with/without beetroot extract 10 g/100 g) on separate occasions. GeXP assay measured whole blood postprandial gene expression profiles of 28 cell defense markers at baseline and postprandial time points 1, 2, 4, 6, 24 h. Plasma markers of metabolic lipids, hormones, inflammatory cytokines, oxidative stress, and DNA damage/repair were also assessed. SIRT 1, UCP2, HO1, GSS, PTGS2, TP53, CDKN2A, PPIA, SOCS3, and APE1 expression profiles revealed distinct stratified subgroups associated with plasma HDLs, TNF-α and postprandial responses of SOCS3, and PPIA. Leptin, IL6, and DNA strand breaks revealed differing responses to fat type consumed. CONCLUSION: This study demonstrates postprandial immune, inflammatory, redox, metabolic, and DNA repair responses that are largely independent of fat type consumed (unsaturated/saturated) or addition of beetroot extract, in apparently healthy individuals. However, postprandial responses can be characterized by regulation of gene expression associated with markers linked to health status and are subject to interindividual variation that can influence postprandial responses.

Cellular defense system gene expression profiling of human whole blood: opportunities to predict health benefits in response to diet.

Diet is a critical factor in the maintenance of human cellular defense systems, immunity, inflammation, redox regulation, metabolism, and DNA repair that ensure optimal health and reduce disease risk. Assessment of dietary modulation of cellular defense systems in humans has been limited due to difficulties in accessing target tissues. Notably, peripheral blood gene expression profiles associated with nonhematologic disease are detectable. Coupled with recent innovations in gene expression technologies, gene expression profiling of human blood to determine predictive markers associated with health status and dietary modulation is now a feasible prospect for nutrition scientists. This review focuses on cellular defense system gene expression profiling of human whole blood and the opportunities this presents, using recent technological advances, to predict health status and benefits conferred by diet.

High-fat diet alters gene expression in the liver and colon: links to increased development of aberrant crypt foci.

BACKGROUND: Obesity is associated with an increased risk of colon cancer. High-fat diets that lead to obesity may be a contributing factor, but the mechanisms are unknown. AIMS: This study examines susceptibility to azoxymethane (AOM)-induced precancerous lesions in mice in response to consumption of either a low or a high-fat diet and associated molecular changes in the liver and colon. METHODS: Gene markers of xenobiotic metabolism, leptin-regulated inflammatory cytokines and proliferation were assessed in liver and colon in response to high-fat feeding to determine links with increased sensitivity to AOM. RESULTS: High-fat feeding increased development of AOM-induced precancerous lesions and was associated with increased CYP2E1 gene expression in the liver, but not the colon. Leptin receptors and the colon stem cell marker (Lgr5) were down-regulated in the proximal colon, with a corresponding up-regulation of the inflammatory cytokine (IL6) in response to high-fat feeding. Notably in the distal colon, where aberrant crypt foci develop in response to AOM, the proliferative stem cell marker, Lgr5, was significantly up-regulated with high-fat feeding. CONCLUSIONS: The current study provides evidence that high-fat diets can alter regulation of molecular markers of xenobiotic metabolism that may expose the colon to carcinogens, in parallel with activation of ß-catenin-regulated targets regulating colon epithelial cells. High-fat diets associated with obesity may alter multiple molecular factors that act synergistically to increase the risk of colon cancer associated with obesity.

Molecular mechanisms linking adipokines to obesity-related colon cancer: focus on leptin.

Obesity is linked to increased risk of colon cancer, currently the third most common cancer. Consequently rising levels of obesity worldwide are likely to significantly impact on obesity-related colon cancers in the decades to come. Understanding the molecular mechanisms whereby obesity increases colon cancer risk is thus a focus for research to inform strategies to prevent the increasing trend in obesity-related cancers. This review will consider research on deregulation of adipokine signalling, a consequence of altered adipokine hormone secretion from excess adipose tissue, with a focus on leptin, which has been studied extensively as a potential mediator of obesity-related colon cancer. Numerous investigations using colon cell lines in vitro, in vivo studies in rodents and investigations of colon cancer patients illuminate the complexity of the interactions of leptin with colon tissues via leptin receptors expressed by the colon epithelium. Although evidence indicates a role for leptin in proliferation of colon epithelial cells in vitro, this has been contradicted by studies in rodent models. However, recent studies have indicated that leptin may influence inflammatory mediators linked with colon cancer and also promote cell growth dependent on genotype and is implicated in growth promotion of colon cancer cells. Studies in human cancer patients indicate that there may be different tumour sub-types with varying levels of leptin receptor expression, indicating the potential for leptin to induce variable responses in the different tumour types. These studies have provided insights into the complex interplay of adipokines with responsive tissues prone to obesity-related colon cancer. Deregulation of adipokine signalling via adipokine receptors located in the colon appears to be a significant factor in obesity-related colon cancer. Molecular profiling of colon tumours will be a useful tool in future strategies to characterise the influence that adipokines may have on tumour development and subsequent therapeutic intervention. Study of the molecular mechanisms linking obesity with cancer also supports recommendations to maintain a normal body weight to reduce the risk of colon cancer.