Systemic Metabolic Alterations Research Articles

Simposio 9: Hígado y diabetes: más allá de la glucemia

Simposio 9: El compromiso hepático en diabetes: más allá del hígadoHígado y diabetes: más allá de la glucemiaLa enfermedad de hígado graso no alcohólico (NAFLD) representa la respuesta hepática al insulto de un metabolismo sistémico alterado. En América del Sur un 25% de los sujetos “sanos” tiene NAFLD, principalmente esteatosis simple (ES), y de éstos un 20% puede progresar a esteato-hepatitis no alcohólica (NASH), que implica la presencia de balonización hepatocitaria e inflamación. Más importante aún es que un 20% de los pacientes con NASH puede progresar a fibrosis, incluso a la cirrosis. Se ha considerado por años a la ES como una enfermedad “benigna”, aunque dicho paradigma se está poniendo en duda a partir del seguimiento de pacientes con biopsias seriadas en los que se vio que hasta un 25% de los pacientes con ES progresó a fibrosis. ¿Por qué es importante identificar a pacientes con fibrosis? Porque ésta se relaciona directamente con mayor mortalidad.

FGF15/19 is required for adipose tissue plasticity in response to thermogenic adaptations

ObjectiveTo determine the role of enterokine FGF15/19 in adipose tissue thermogenic adaptations. MethodsCirculating FGF19 and gene expression (qRT-PCR) levels were assessed in subcutaneous adipose tissue from obese human patients. Effects of experimentally increased FGF15 and FGF19 levels in vivo were determined in mice using adenoviral and adeno-associated vectors. Adipose tissues were characterized in FGF15-null mice under distinct cold-related thermogenic challenges. The analyses spanned metabolic profiling, tissue characterization, histology, gene expression, and immunoblot assays. ResultsIn humans, FGF19 levels are directly associated with UCP1 gene expression in subcutaneous adipose tissue. Experimental increases in FGF15 or FGF19 induced white fat browning in mice as demonstrated by the appearance of multilocular beige cells and markers indicative of a beige phenotype, including increased UCP1 protein levels. Mice lacking FGF15 showed markedly impaired white adipose tissue browning and a mild reduction in parameters indicative of BAT activity in response to cold-induced environmental thermogenic challenges. This was concomitant with signs of altered systemic metabolism, such as reduced glucose tolerance and impaired cold-induced insulin sensitization. ConclusionsEnterokine FGF15/19 is a key factor required for adipose tissue plasticity in response to thermogenic adaptations.

Subchronic exposure to concentrated ambient PM2.5 perturbs gut and lung microbiota as well as metabolic profiles in mice.

Exposure to ambient fine particular matter (PM2.5) are linked to an increased risk of metabolic disorders, leading to enhanced rate of many diseases, such as inflammatory bowel disease (IBD), cardiovascular diseases, and pulmonary diseases; nevertheless, the underlying mechanisms remain poorly understood. In this study, BALB/c mice were exposed to filtered air (FA) or concentrated ambient PM2.5 (CPM) for 2 months using a versatile aerosol concentration enrichment system(VACES). We found subchronic CPM exposure caused significant lung and intestinal damage, as well as systemic inflammatory reactions. In addition, serum and BALFs (bronchoalveolar lavage fluids) metabolites involved in many metabolic pathways in the CPM exposed mice were markedly disrupted upon PM2.5 exposure. Five metabolites (glutamate, glutamine, formate, pyruvate and lactate) with excellent discriminatory power (AUC=1, p<0.001) were identified to predict PM2.5 exposure related toxicities. Furthermore, subchronic exposure to CPM not only significantly decreased the richness and composition of the gut microbiota, but also the lung microbiota. Strong associations were found between several gut and lung bacterial flora changes and systemic metabolic abnormalities. Our study showed exposure to ambient PM2.5 not only caused dysbiosis in the gut and lung, but also significant systemic and local metabolic alterations. Alterations in gut and lung microbiota were strongly correlated with metabolic abnormalities. Our study suggests potential roles of gut and lung microbiota in PM2.5 caused metabolic disorders.

Targeting T-cell oxidative metabolism to improve influenza survival in a mouse model of obesity.

BackgroundObesity is associated with impaired primary and secondary immune responses to influenza infection, with T cells playing a critical role. T cell function is highly influenced by the cellular metabolic state; however, it remains unknown how altered systemic metabolism in obesity alters T cell metabolism and function to influence immune response. Our objective was to identify the altered cellular metabolic state of T cells from obese mice so that we may target T cell metabolism to improve immune response to infection.MethodsMice were fed normal chow or high-fat diet for 18–19 weeks. Changes in T cell populations were analyzed in both adipose tissue and spleens using flow cytometry. Splenic T cells were further analyzed for nutrient uptake and extracellular metabolic flux. As changes in T cell mitochondrial oxidation were observed in obesity, obese mice were treated with metformin for six weeks and compared to lean control mice or obese mice undergoing weight loss through diet switch; immunity was measured by survival to influenza infection.ResultsWe found changes in T cell populations in adipose tissue of high-fat diet-induced obese mice, characterized by decreased proportions of Treg cells and increased proportions of CD8+ T cells. Activated CD4+ T cells from obese mice had increased glucose uptake and oxygen consumption rate (OCR), compared to T cells from lean controls, indicating increased mitochondrial oxidation of glucose. Treatment of isolated CD4+ T cells with metformin was found to inhibit OCR in vitro and alter the expression of several activation markers. Lastly, treatment of obese mice with metformin, but not weight loss, was able to improve survival to influenza in obesity.ConclusionsT cells from obese mice have an altered metabolic profile characterized by increased glucose oxidation, which can be targeted to improve survival against influenza infection.

GH directly inhibits steatosis and liver injury in a sex-dependent and IGF1-independent manner.

A reduction in hepatocyte growth hormone (GH)-signaling promotes non-alcoholic fatty liver disease (NAFLD). However, debate remains as to the relative contribution of the direct effects of GH on hepatocyte function vs indirect effects, via alterations in insulin-like growth factor 1 (IGF1). To isolate the role of hepatocyte GH receptor (GHR) signaling, independent of changes in IGF1, mice with adult-onset, hepatocyte-specific GHR knockdown (aHepGHRkd) were treated with a vector expressing rat IGF1 targeted specifically to hepatocytes. Compared to GHR-intact mice, aHepGHRkd reduced circulating IGF1 and elevated GH. In male aHepGHRkd, the shift in IGF1/GH did not alter plasma glucose or non-esterified fatty acids (NEFA), but was associated with increased insulin, enhanced systemic lipid oxidation and reduced white adipose tissue (WAT) mass. Livers of male aHepGHRkd exhibited steatosis associated with increased de novo lipogenesis, hepatocyte ballooning and inflammation. In female aHepGHRkd, hepatic GHR protein levels were not detectable, but moderate levels of IGF1 were maintained, with minimal alterations in systemic metabolism and no evidence of steatosis. Reconstitution of hepatocyte IGF1 in male aHepGHRkd lowered GH and normalized insulin, whole body lipid utilization and WAT mass. However, IGF1 reconstitution did not reduce steatosis or eliminate liver injury. RNAseq analysis showed IGF1 reconstitution did not impact aHepGHRkd-induced changes in liver gene expression, despite changes in systemic metabolism. These results demonstrate the impact of aHepGHRkd is sexually dimorphic and the steatosis and liver injury observed in male aHepGHRkd mice is autonomous of IGF1, suggesting GH acts directly on the adult hepatocyte to control NAFLD progression.

Metformin enhances protection in guinea pigs chronically infected with Mycobacterium tuberculosis

Tuberculosis (TB) is a chronic inflammatory disease that is often associated with alterations in systemic and cellular metabolism that resolves following successful antimicrobial drug treatment. We hypothesized that altered systemic glucose metabolism as a consequence of Mycobacterium tuberculosis (Mtb) infection, contributes to TB pathogenesis, and when normalized with anti-glycemic drugs would improve clinical outcomes. To test this hypothesis, guinea pigs were treated daily with the anti-diabetic drug metformin starting 4 weeks prior or concurrent with aerosol exposure to the H37Rv strain of Mtb. In the chronic stages of infection, Mtb infected metformin-treated animals had restored systemic insulin sensitivity but remained glucose intolerant as determined by oral glucose tolerance testing. Despite persistent glucose intolerance, metformin-treated guinea pigs had a 2.8-fold reduction in lung lesion burden and a 0.7 log decrease in CFUs. An alternative hypothesis that metformin treatment improved clinical disease by having a direct effect on immune cell energy metabolism was tested using extracellular flux analysis and flow cytometry. The proinflammatory immune response to Mtb infection in untreated guinea pigs was associated with a marked increase in energy metabolism (glycolysis and mitochondrial respiration) of peripheral blood mononuclear cells (PBMCs), which was normalized in metformin-treated guinea pigs. Moreover, both CD4+ and CD8+ T lymphocytes from Mtb infected, metformin treated animals maintained a more normal mitochondrial membrane potential while those isolated from untreated animals had persistent mitochondrial hyperpolarization. These data suggest that metformin promotes natural host resistance to Mtb infection by maintaining immune cell metabolic homeostasis and function during the chronic stages of active TB disease.

Metabolomic Profiling Reveals Distinct and Mutual Effects of Diet and Inflammation in Shaping Systemic Metabolism in Ldlr-/- Mice.

Changes in modern dietary habits such as consumption of Western-type diets affect physiology on several levels, including metabolism and inflammation. It is currently unclear whether changes in systemic metabolism due to dietary interventions are long-lasting and affect acute inflammatory processes. Here, we investigated how high-fat diet (HFD) feeding altered systemic metabolism and the metabolomic response to inflammatory stimuli. We conducted metabolomic profiling of sera collected from Ldlr−/− mice on either regular chow diet (CD) or HFD, and after an additional low-dose lipopolysaccharide (LPS) challenge. HFD feeding, as well as LPS treatment, elicited pronounced metabolic changes. HFD qualitatively altered the systemic metabolic response to LPS; particularly, serum concentrations of fatty acids and their metabolites varied between LPS-challenged mice on HFD or CD, respectively. To investigate whether systemic metabolic changes were sustained long-term, mice fed HFD were shifted back to CD after four weeks (HFD > CD). When shifted back to CD, serum metabolites returned to baseline levels, and so did the response to LPS. Our results imply that systemic metabolism rapidly adapts to dietary changes. The profound systemic metabolic rewiring observed in response to diet might affect immune cell reprogramming and inflammatory responses.

Excess Body Weight and Cancer-Related Fatigue, Systemic Inflammation, and Serum Lipids in Breast Cancer Survivors

Background Cancer-related fatigue (CRF) is a common side effect impacting breast cancer survivors. Research points to a relationship between obesity and CRF in breast cancer survivors related to elevated systemic inflammation and metabolic alterations. Methods This cross-sectional study examined the relationship of obesity to CRF, inflammatory markers and serum lipids through a secondary analysis of a nationwide randomized controlled trial. Breast cancer survivors with CRF were categorized based on BMI category. Symptoms of CRF, inflammatory markers and serum fatty acids were assessed among groups. Results There were 105 breast cancer survivors in the analysis. BMI was positively associated with CRF based on MFSI General (p = 0.020; 95% C.I. 0.024, 0.273) and MFSI Physical (p = 0.013; 95% C.I. 0.035, 0.298) subscales. TNF-α (p = 0.007; 95% C.I. 0.007, 0.044), and IL-6 (p = 0.020; 95% C.I. 0.006, 0.073) were elevated in the obese. Monounsaturated fatty acid levels (p = 0.047; 95% C.I. 0.000, 0.053) and the omega-6 to omega-3 fatty acid ratio were associated with obesity (p = 0.047; 95% C.I. 0.002, 0.322). Conclusions Obese breast cancer survivors had greater levels of CRF, inflammatory markers and certain fatty acids. Inflammatory markers and fatty acids were not found to have any mediating or positive association with CRF variables in this analysis. NCT02352779.

Transplanted Kidney Increases Nitric Oxide Formation With Metabolic Acidosis Reduction.

As a vasodilator, nitric oxide is considered to play a significant role in the homeostatic regulation of renal hemodynamics. To test the hypothesis that a kidney graft is capable of producing nitric oxide immediately after renal transplant surgery, we examined the possibility that it positively affects local metabolic acidosis. In kidney transplant recipients, we analyzed renal vein and central vein blood samples, which reflect local and systemic metabolic alterations, respectively. Samples were taken immediately after kidney recirculation (that is, the first blood passing through after clamps are released) and at 5, 15, and 30 minutes thereafter. Levels of nitric oxide metabolites (nitrites, nitrates, and their sum), malondialdehyde (an indicator of oxidative damages), and parameters of acid-base balance (pH level, actual excess base, hemoglobin, actual bicarbonate, partial pressure of carbon dioxide, partial pressure of oxygen) were analyzed. Living kidney donors (the recipients' parents) were controls. In renal vein samples, nitrates and the sum of nitrites and nitrates were significantly higher than that shown in control (P < .001) and central vein (P < .05) samples, suggesting an immediate increase in nitric oxide production in the transplanted organ. Metabolic acidosis occurred in both the renal and central vein, indicated by decreased pH and actual bicarbonate level as well as by negative actual base excess level. Only in the renal vein was an increased nitrite and nitrate associated with a reduction of negative actual excess base, thereby suggesting a decrease in anion formation. Transplanted kidneys increase nitric oxide production immediately after organ transplant surgery, which positively affects local metabolic acidosis. The mechanism for this effect is likely local circulation improvement.

0346 Metabolic Aging and Sleep Loss: Metabolite Signatures Link Sleep Deprivation and Aging Across Tissues

Abstract Introduction Insufficient sleep is a hallmark of modern society, and sleep deprivation (SD) is a risk factor for neurodegenerative and cardiometabolic disorders. The interactions of aging with systemic and local metabolic alterations induced by sleep deprivation are essentially unexplored. In this study, we demonstrate a shared metabolic imprint of SD and aging in plasma, liver, and hippocampus. Methods Young (2 - 4 months) and aged (22 - 24 months) mice were sleep deprived (N = 10/group) for 5 hours followed by collection of blood plasma, liver and hippocampus. The samples were extracted and subjected to UPLC-MS/MS based targeted metabolomics analysis. Results Young animals displayed greater sensitivity to SD induced metabolic changes with &amp;gt;40% more metabolites perturbed in each sample type measured compared to aged animals. Enrichment analysis based on known disease-associated metabolites suggests that plasma change in young animals are of pathological relevance, but not in aged animals. A common hepatic signature of sleep-loss across the two age groups consisted of ketosis and urea cycle perturbation. Approximately 20-30% of measured metabolites exhibit similar changes when the sleep deprivation induced signature is compared with the aging metabolic imprint in a tissue-dependent manner. Central energetics, urea cycle and aromatic amino acid metabolism highlight the common pathways altered by sleep and aging in the periphery. In the hippocampus, choline and acetylcholine pools were depleted, potentially providing insight into the changes in metabolism that accompany analogous defects in memory consolidation. Conclusion These results support the notion that SD makes the ‘young seem old’. The results further connect neurobehavioral observations tying together aging and sleep loss, by implicating molecular mechanisms at the level of metabolism. Support This work was supported by NIH grant R21AG052905 (AMW, AS), P50AG017628 (TA; A.I. Pack, PI) and R01AG062398 (TA, JT). TA was supported by the Brush Family Chair in Biology at Penn and is currently supported by the Roy J. Carver Chair of Neuroscience at Iowa.

Biological sex and DNA repair deficiency drive Alzheimer's disease via systemic metabolic remodeling and brain mitochondrial dysfunction.

Alzheimer's disease (AD) is an incurable neurodegenerative disease that is more prevalent in women. The increased risk of AD in women is not well understood. It is well established that there are sex differences in metabolism and that metabolic alterations are an early component of AD. We utilized a cross-species approach to evaluate conserved metabolic alterations in the serum and brain of human AD subjects, two AD mouse models, a human cell line, and two Caenorhabditis elegans AD strains. We found a mitochondrial complex I-specific impairment in cortical synaptic brain mitochondria in female, but not male, AD mice. In the hippocampus, Polβ haploinsufficiency caused synaptic complex I impairment in male and female mice, demonstrating the critical role of DNA repair in mitochondrial function. In non-synaptic, glial-enriched, mitochondria from the cortex and hippocampus, complex II-dependent respiration increased in female, but not male, AD mice. These results suggested a glial upregulation of fatty acid metabolism to compensate for neuronal glucose hypometabolism in AD. Using an unbiased metabolomics approach, we consistently observed evidence of systemic and brain metabolic remodeling with a shift from glucose to lipid metabolism in humans with AD, and in AD mice. We determined that this metabolic shift is necessary for cellular and organismal survival in C. elegans, and human cell culture AD models. We observed sex-specific, systemic, and brain metabolic alterations in humans with AD, and that these metabolite changes significantly correlate with amyloid and tau pathology. Among the most significant metabolite changes was the accumulation of glucose-6-phosphate in AD, an inhibitor of hexokinase and rate-limiting metabolite for the pentose phosphate pathway (PPP). Overall, we identified novel mechanisms of glycolysis inhibition, PPP, and tricarboxylic acid cycle impairment, and a neuroprotective augmentation of lipid metabolism in AD. These findings support a sex-targeted metabolism-modifying strategy to prevent and treat AD.

Spectrofluorometric Analysis of Autofluorescing Components of Crude Serum from a Rat Liver Model of Ischemia and Reperfusion.

Autofluorescence (AF) of crude serum was investigated with reference to the potential of its intrinsic AF biomarkers for the noninvasive diagnosis of liver injury. Spectral parameters of pure compounds representing retinol (vitamin A) and fluorescing free fatty acids were characterized by spectrofluorometry, to assess spectral parameters for the subsequent AF analysis of serum, collected from rats undergoing liver ischemia/reperfusion (I/R). Differences in AF spectral profiles detected between control and I/R were due to the increase in the AF components representing fatty acids in I/R serum samples. No significant changes occurred for retinol levels, consistently with the literature reporting that constant retinol levels are commonly observed in the blood, except for malnutrition or chronic severe liver disease. Conversely, fatty acids, in particular arachidonic and linoleic acid and their derivatives, act as modulating agents in inflammation, representing both a protective and damaging response to stress stimuli. The biometabolic and pathophysiological meaning of serum components and the possibility of their direct detection by AF spectrofluorometry open up interesting perspectives for the development of AF serum analysis, as a direct, cost effective, supportive tool to assess liver injury and related systemic metabolic alterations, for applications in experimental biomedicine and foreseen translation to the clinics.

Impact of high-fat overfeeding on white adipose tissue and systemic metabolic and inflammatory responses

AbstractWhite adipose tissue (WAT) inflammation is linked to the development of cardiometabolic disease. A high intake of saturated fatty acids (SFA) may promote a more pro-inflammatory WAT gene expression profile, compared to monounsaturated fatty acids(1,2). This is concerning as the UK adult population currently exceeds the SFA intake target of &lt; 10% total energy (TE), at 11.9%TE(3). However, further research is needed to understand how SFA ingestion impacts the protein content and phosphorylation of key targets involved in WAT inflammatory signalling. Therefore, this study investigated the effect of short-term, high-fat overfeeding on WAT and systemic metabolic and inflammatory responses in healthy, non-obese individuals.Fifteen (9 men, 6 women) apparently healthy participants (mean (SE) age; 26.6 (1.2) y, BMI; 24.4 (0.6) kg/m2) consumed a high-fat (dietary target: 65.0%TE total fat; 32.5%TE SFA), high-calorie (+ 50% estimated energy requirements) diet for 7 days. Fasted venous blood and WAT samples were collected pre- and post-intervention.Body mass increased following the intervention (pre-intervention vs. post-intervention: 75.2 (2.9) kg vs. 76.4 (2.9) kg; P &lt; 0.0001). The intervention also led to increases in glucose (4.4 (0.1) vs. 4.6 (0.1) mmol/L; P = 0.022) and lipopolysaccharide-binding protein (12.9 (1.3) vs. 17.7 (3.0) μg/mL; P = 0.038), and a decrease in triacylglycerol (0.91 (0.08) vs. 0.72 (0.05) mmol/L; P = 0.007). Insulin, IL-6 and soluble CD14 concentrations remained unchanged (all P &gt; 0.05). At the WAT level, total protein (TLR4; NF-κB; IKβα; P38; MCP-1) and phosphorylation (p) of proteins (p-NF-κB; p-IKβα; p-P38) involved in inflammatory signalling were unchanged following the intervention (all P &gt; 0.05).In conclusion, although short-term, high-fat overfeeding led to an increase in body mass as well as systemic metabolic alterations, the content and phosphorylation of proteins involved in WAT inflammatory signalling were unaltered in healthy, non-obese individuals. Further analysis will reveal the impact of high-fat overfeeding on peripheral blood monocyte populations, which are involved in mediating pro- and anti-inflammatory responses.This research was supported by a Society for Endocrinology Early Career Grant.

Abstract I19: Early detection of pancreatic cancer: Challenges and opportunities

Abstract Research in early detection of pancreatic cancer is considered one of the highest priority areas by the National Cancer Institute (NCI) in its updated Roadmap for Progress in Pancreatic Ductal Adenocarcinoma (2019). However, current United States Screening and Prevention Task Force (USPSTF) guidelines recommend against screening for pancreatic cancer in the general population, due to the lack of credentialed biomarkers and the considerable potential for overdiagnosis. On the contrary, individuals at high-risk for pancreatic cancer represent an opportunity for cancer interception, including the conduct of imaging and biomarker validation studies in prospective cohorts. High-risk cohorts ripe for surveillance include individuals harboring germline deleterious mutations, those with pancreatic mucinous cystic lesions, and patients with new onset diabetes. Approximately 10% of pancreatic cancer patients carry germline mutations in genes such as BRCA1/2, ATM, PALB2, CDKN2A, and mismatch repair genes, amongst others. In the past year, the National Comprehensive Cancer Network (NCCN) guideline for germline testing has evolved towards a recommendation of “universal testing” in all index cases, which has been facilitated through the availability of relatively cheap CLIA multi-gene panels. “Cascade testing” of unaffected family members can identify asymptomatic individuals who might benefit from surveillance. Notably, the risk of harboring or developing pancreatic cancer varies widely between carrier mutations, and the guidelines for screening modality and interval are still evolving. A second high-risk group includes individuals with mucinous pancreatic cysts. It is important to reiterate that the overwhelming majority of patients with mucinous cysts will not progress to cancer, and routinely used clinical and imaging criteria can lead to overtreatment in a significant minority of patients. Thus, algorithms that improve the management of cystic lesions using the confluence of clinical, radiological, biochemical and molecular parameters are under active development. Pancreatic cancer is a “diabetogenic” neoplasm, with over three quarters of patients developing some measure of paraneoplastic aberration in glucose homeostasis. While 25-40% of pancreatic cancer patients present with frank new onset or worsening diabetes (classified as Type 3c diabetes) less than 1% of patients with new onset diabetes harbor an asymptomatic cancer. Thus, while adult new onset diabetes represents a high-risk population, significant enrichment of this population is needed in order to enable a clinically feasible early detection program. Algorithms such as “Enriching New Onset Diabetes for Pancreatic Cancer” (ENDPAC) that leverage structured data within electronic medical records (EMR) will enable the selection of individuals with the highest probability of subclinical disease. Following the discussion on high risk cohorts, we will pivot to some of the current challenges underlying biomarker development in the context of early detection, and why CA19-9 remains the only FDA approved biomarker for this disease despite 1000s of publications on this subject. Finally, we will briefly allude to how imaging modalities might be utilized in the context of localizing subclinical disease, including recent data on extra-pancreatic alterations induced by systemic metabolic alterations by the developing neoplasm that can be detected using standard of care imaging assays. Early detection of pancreatic cancer continues to be a challenging conundrum, but sustained investment and team science efforts facilitated by the National Cancer Institute and foundations, including the Lustgarten Foundation, Pancreatic Cancer Action Network and Cancer Research UK, are making tangible advances within this space. Citation Format: Anirban Maitra. Early detection of pancreatic cancer: Challenges and opportunities [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr I19.

Virus-Induced Interferon Regulates the Urea Cycle

Integrating transcriptomic, proteomic, and metabolomic data, Lercher etal. show in a mouse model of LCMV infection that type I interferon alters the expression and function of key enzymes of the urea cycle in hepatocytes. This results in altered systemic metabolism, attenuating antiviral Tcell responses and ameliorating liver injury.

Systemic and central nervous system metabolic alterations in Alzheimer\u2019s disease

BackgroundMetabolic alterations, related to cerebral glucose metabolism, brain insulin resistance, and age-induced mitochondrial dysfunction, play an important role in Alzheimer’s disease (AD) on both the systemic and central nervous system level. To study the extent and significance of these alterations in AD, quantitative metabolomics was applied to plasma and cerebrospinal fluid (CSF) from clinically well-characterized AD patients and cognitively healthy control subjects. The observed metabolic alterations were associated with core pathological processes of AD to investigate their relation with amyloid pathology and tau-related neurodegeneration.MethodsIn a case-control study of clinical and biomarker-confirmed AD patients (n = 40) and cognitively healthy controls without cerebral AD pathology (n = 34) with paired plasma and CSF samples, we performed metabolic profiling, i.e., untargeted metabolomics and targeted quantification. Targeted quantification focused on identified deregulated pathways highlighted in the untargeted assay, i.e. the TCA cycle, and its anaplerotic pathways, as well as the neuroactive tryptophan and kynurenine pathway.ResultsConcentrations of several TCA cycle and beta-oxidation intermediates were higher in plasma of AD patients, whilst amino acid concentrations were significantly lower. Similar alterations in these energy metabolism intermediates were observed in CSF, together with higher concentrations of creatinine, which were strongly correlated with blood-brain barrier permeability. Alterations of several amino acids were associated with CSF Amyloidβ1–42. The tryptophan catabolites, kynurenic acid and quinolinic acid, showed significantly higher concentrations in CSF of AD patients, which, together with other tryptophan pathway intermediates, were correlated with either CSF Amyloidβ1–42, or tau and phosphorylated Tau-181.ConclusionsThis study revealed AD-associated systemic dysregulation of nutrient sensing and oxidation and CNS-specific alterations in the neuroactive tryptophan pathway and (phospho)creatine degradation. The specific association of amino acids and tryptophan catabolites with AD CSF biomarkers suggests a close relationship with core AD pathology.Our findings warrant validation in independent, larger cohort studies as well as further investigation of factors such as gender and APOE genotype, as well as of other groups, such as preclinical AD, to identify metabolic alterations as potential intervention targets.

High-fat diet fuels prostate cancer progression by rewiring the metabolome and amplifying the MYC program

Systemic metabolic alterations associated with increased consumption of saturated fat and obesity are linked with increased risk of prostate cancer progression and mortality, but the molecular underpinnings of this association are poorly understood. Here, we demonstrate in a murine prostate cancer model, that high-fat diet (HFD) enhances the MYC transcriptional program through metabolic alterations that favour histone H4K20 hypomethylation at the promoter regions of MYC regulated genes, leading to increased cellular proliferation and tumour burden. Saturated fat intake (SFI) is also associated with an enhanced MYC transcriptional signature in prostate cancer patients. The SFI-induced MYC signature independently predicts prostate cancer progression and death. Finally, switching from a high-fat to a low-fat diet, attenuates the MYC transcriptional program in mice. Our findings suggest that in primary prostate cancer, dietary SFI contributes to tumour progression by mimicking MYC over expression, setting the stage for therapeutic approaches involving changes to the diet.

Association between Diabetes and Keratoconus: A Retrospective Analysis

Keratoconus (KC) and chronic diabetes mellitus (DM) are both associated with significant defects in the human corneal structure. Studies have long suggested that DM is linked to KC, mainly via the crosslinking mechanism, but scientific evidences are lacking. The role of altered systemic metabolism is well-established in both DM and KC with studies suggesting localized altered cellular metabolism leading to the development of corneal pathologies. We have previously characterized the metabolic defects associated with both conditions using targeted metabolomics. To compare metabolic differences between KC and DM-derived corneal fibroblasts, we performed a respective study of two cohorts of the KC and DM populations using a retrospective analysis of targeted metabolomics data. The goal of this study was to identify the group of differentially regulated metabolites, in KC versus DM, so that we may unravel the link between the two devastating corneal pathologies.

Systemic and Local Metabolic Alterations in Sleep-Deprivation-Induced Stress: A Multiplatform Mass-Spectrometry-Based Lipidomics and Metabolomics Approach.

Sleep deprivation (SD) is known to be associated with metabolic disorders and chronic diseases. Complex metabolic alterations induced by SD at omics scale and the associated biomarker candidates have been proposed. However, in vivo systemic and local metabolic shift patterns of the metabolome and lipidome in acute and chronic partial SD models remain to be elucidated. In the present study, the serum, hypothalamus, and hippocampus CA1 of sleep-deprived rats (SD rats) from acute and chronic sleep restriction models were analyzed using three different omics platforms for the discovery and mechanistic assessment of systemic and local SD-induced dysregulated metabolites. We found a similar pattern of systemic metabolome alterations between two models, for which the area under the curve (AUC) of receiver operating characteristic curves was AUC = 0.847 and 0.930 with the pseudotargeted and untargeted metabolomics approach, respectively. However, SD-induced systemic lipidome alterations were significantly different and appeared to be model-dependent (AUC = 0.374). Comprehensive pathway analysis of the altered lipidome and metabolome in the hypothalamus indicated the abnormal behavior of eight metabolic and lipid metabolic pathways. The metabolic alterations of the hippocampus CA1 was subtle in two SD models. Collectively, these results extend our understanding of the quality of sleep and suggest metabolic targets in developing diagnostic biomarkers for better SD control.

Nutritional Modulation of Immune and Central Nervous System Homeostasis: The Role of Diet in Development of Neuroinflammation and Neurological Disease.

The gut-microbiome-brain axis is now recognized as an essential part in the regulation of systemic metabolism and homeostasis. Accumulating evidence has demonstrated that dietary patterns can influence the development of metabolic alterations and inflammation through the effects of nutrients on a multitude of variables, including microbiome composition, release of microbial products, gastrointestinal signaling molecules, and neurotransmitters. These signaling molecules are, in turn, implicated in the regulation of the immune system, either promoting or inhibiting the production of pro-inflammatory cytokines and the expansion of specific leukocyte subpopulations, such as Th17 and Treg cells, which are relevant in the development of neuroinflammatory and neurodegenerative conditions. Metabolic diseases, like obesity and type 2 diabetes mellitus, are related to inadequate dietary patterns and promote variations in the aforementioned signaling pathways in patients with these conditions, which have been linked to alterations in neurological functions and mental health. Thus, maintenance of adequate dietary patterns should be an essential component of any strategy aiming to prevent neurological pathologies derived from systemic metabolic alterations. The present review summarizes current knowledge on the role of nutrition in the modulation of the immune system and its impact in the development of neuroinflammation and neurological disease.