High-Fat Diet-Induced Obesity Increases Brain Mitochondrial Complex I and Lipoxidation-Derived Protein Damage.

Obesity is a risk factor for highly prevalent age-related neurodegenerative diseases, the pathogenesis of whichinvolves mitochondrial dysfunction and protein oxidative damage. Lipoxidation, driven by high levels of peroxidizable unsaturated fatty acids and low antioxidant protection of the brain, stands out as a significant risk factor. To gain information on the relationship between obesity and brain molecular damage, in a porcine model of obesity we evaluated (1) the level of mitochondrial respiratory chain complexes, as the main source of free radical generation, by Western blot; (2) the fatty acid profile by gas chromatography; and (3) the oxidative modification of proteins by mass spectrometry. The results demonstrate a selectively higher amount of the lipoxidation-derived biomarker malondialdehyde-lysine (MDAL) (34% increase) in the frontal cortex, and positive correlations between MDAL and LDL levels and body weight. No changes were observed in brain fatty acid profile by the high-fat diet, and the increased lipid peroxidative modification was associated with increased levels of mitochondrial complex I (NDUFS3 and NDUFA9 subunits) and complex II (flavoprotein). Interestingly, introducing n3 fatty acids and a probiotic in the high-fat diet prevented the observed changes, suggesting that dietary components can modulate protein oxidative modification at the cerebral level and opening new possibilities in neurodegenerative diseases' prevention.

Placental AA/EPA Ratio Is Associated with Obesity Risk Parameters in the Offspring at 6 Years of Age.

During pregnancy, maternal polyunsaturated fatty acids (PUFA) are transferred to the fetus through the placenta by specific FA transporters (FATP). A higher perinatal exposure to n-6 over n-3 PUFA could be linked to excess fat mass and obesity development later in life. In this context, we aimed to assess the associations between long chain PUFAs (LC-PUFAs) (n-6, n-3, and n-6/n-3 ratios) measured in the placenta at term birth with obesity-related parameters in the offspring at 6 years of age and assess whether these associations are dependent on the placental relative expression of fatty acid transporters. As results, the PUFAn-6/PUFAn-3 ratio was 4/1, which scaled up to 15/1 when considering only the arachidonic acid/eicosapentaenoic acid ratio (AA/EPA ratio). Positive associations between the AA/EPA ratio and offspring's obesity risk parameters were found with weight-SDS, BMI-SDS, percent fat mass-SDS, visceral fat, and HOMA-IR (r from 0.204 to 0.375; all p < 0.05). These associations were more noticeable in those subjects with higher expression of fatty acid transporters. Therefore, in conclusion, a higher placental AA/EPA ratio is positively associated with offspring's visceral adiposity and obesity risk parameters, which become more apparent in subjects with higher expressions of placental FATPs. Our results support the potential role of n-6 and n-3 LC-PUFA in the fetal programming of obesity risk in childhood. For the present study, 113 healthy pregnant women were recruited during the first trimester of pregnancy and their offspring were followed up at 6 years of age. The fatty acid profiles and the expression of fatty acid transporters (FATP1 and FATP4) were analyzed from placental samples at birth. Associations between LC-PUFA (n-6, n-3, and n-6/n-3 ratios) and obesity risk parameters (weight, body mass index (BMI), percent fat mass, visceral fat, and homeostatic model assessment of insulin resistance (HOMA-IR)) in the offspring at 6 years of age were examined.

Methionine Metabolism Is Down-Regulated in Heart of Long-Lived Mammals.

Methionine constitutes a central hub of intracellular metabolic adaptations leading to an extended longevity (maximum lifespan). The present study follows a comparative approach analyzing methionine and related metabolite and amino acid profiles using an LC-MS/MS platform in the hearts of seven mammalian species with a longevity ranging from 3.8 to 57 years. Our findings demonstrate the existence of species-specific heart phenotypes associated with high longevity characterized by: (i) low concentration of methionine and its related sulphur-containing metabolites; (ii) low amino acid pool; and (iii) low choline concentration. Our results support the existence of heart metabotypes characterized by a down-regulation in long-lived species, supporting the idea that in longevity, less is more.

Colonic Microbiota Profile Characterization of the Responsiveness to Dietary Fibre Treatment in Hypercholesterolemia.

This study aimed to determine how the microbiota profile might be predisposed to a better response in blood lipid profiles due to dietary fibre supplementation. A three-arm intervention study that included three different fibre types (mainly insoluble, soluble, and antioxidant fibre) supplemented (19.2 g/day) during 2 months in individuals with hypercholesterolemia was developed. Changes in faecal microbiota and blood lipid profile after fibre supplementation were determined. In all volunteers, regardless of fibre type, an increase in the abundance of Bifidobacterium was observed, and similarly, an inverse relationship between faecal propionic acid and blood LDL-cholesterol, LDL particle size, and LDL/HDL particle ratio (p-values 0.0067, 0.0002, and 0.0067, respectively) was observed. However, not all volunteers presented an improvement in lipid profile. The non-responders to fibre treatment showed a decrease in microbiota diversity (Shannon and Simpson diversity index p-values of 0.0110 and 0.0255, respectively) after the intervention; where the reduction in short-chain fatty acids (SCFAs) producing bacterial genera such as Clostridium XIVa and Ruminococcus after dietary fibre treatment was the main difference. It was concluded that the non-responsiveness to dietary fibre treatment might be mediated by the lack of ability to maintain a stable SCFA producing bacteria diversity and composition after extra fibre intake.

Gut microbes shape microglia and cognitive function during malnutrition.

Fecal-oral contamination promotes malnutrition pathology. Lasting consequences of early life malnutrition include cognitive impairment, but the underlying pathology and influence of gut microbes remain largely unknown. Here, we utilize an established murine model combining malnutrition and iterative exposure to fecal commensals (MAL-BG). The MAL-BG model was analyzed in comparison to malnourished (MAL mice) and healthy (CON mice) controls. Malnourished mice display poor spatial memory and learning plasticity, as well as altered microglia, non-neuronal CNS cells that regulate neuroimmune responses and brain plasticity. Chronic fecal-oral exposures shaped microglial morphology and transcriptional profile, promoting phagocytic features in MAL-BG mice. Unexpectedly, these changes occurred independently from significant cytokine-induced inflammation or blood-brain barrier (BBB) disruption, key gut-brain pathways. Metabolomic profiling of the MAL-BG cortex revealed altered polyunsaturated fatty acid (PUFA) profiles and systemic lipoxidative stress. In contrast, supplementation with an ω3 PUFA/antioxidant-associated diet (PAO) mitigated cognitive deficits within the MAL-BG model. These findings provide valued insight into the malnourished gut microbiota-brain axis, highlighting PUFA metabolism as a potential therapeutic target.

Restriction of Dietary Advanced Glycation End Products Induces a Differential Plasma Metabolome and Lipidome Profile.

SCOPE: Diets with low content in advanced glycation end products (AGEs) lead to beneficial properties in highly prevalent age-related diseases. To shed light on the mechanisms behind, the changes induced by a low AGE dietary intervention in the circulating metabolome are analyzed. METHODS AND RESULTS: To this end, 20 non-diabetic patients undergoing peritoneal dialysis are randomized to continue their usual diet or to one with a low content of AGEs for 1 month. Then, plasmatic metabolome and lipidomes are analyzed by liquid-chromatography coupled to mass spectrometry. The levels of defined AGE structures are also quantified by ELISA and by mass-spectrometry. The results show that the low AGE diet impinged significant changes in circulating metabolomes (166 molecules) and lipidomes (91 lipids). Metabolic targets of low-AGE intake include sphingolipid, ether-lipids, and glycerophospholipid metabolism. Further, it reproduces some of the plasma characteristics of healthy aging. CONCLUSION: The finding of common pathways induced by low-AGE diets with previous metabolic traits implicated in aging, insulin resistance, and obesity suggest the usefulness of the chosen approach and supports the potential extension of this study to other populations.

Methionine transsulfuration pathway is upregulated in long-lived humans.

Available evidences point to methionine metabolism as a key target to study the molecular adaptive mechanisms underlying differences in longevity. The plasma methionine metabolic profile was determined using a LC-MS/MS platform to systematically define specific phenotypic patterns associated with genotypes of human extreme longevity (centenarians). Our findings demonstrate the presence of a specific plasma profile associated with human longevity characterized by an enhanced transsulfuration pathway and tricarboxylic acid (TCA) cycle intermediates, as well as a reduced content of specific amino acids. Furthermore, our work reveals that centenarians maintain a strongly correlated methionine metabolism, suggesting an improved network integrity, homeostasis and more tightly regulated metabolism. We have discovered a particular methionine signature related to the condition of extreme longevity, allowing the identification of potential mechanisms and biomarkers of healthy aging.

Molecular phenomics of a high-calorie diet-induced porcine model of prepubertal obesity.

As obesity incidence is alarmingly rising among young individuals, we aimed to characterize an experimental model of this situation, considering the similarity between human and porcine physiology. For this reason, we fed prepubertal (63 days old) Duroc breed females (n=21) either with a standard growth diet (3800 kcal/day) or one with a high-calorie content (5200 kcal/day) during 70 days. Computerized tomography, mass-spectrometry-based metabolomics and lipidomics, as well as peripheral blood mononuclear cell transcriptomics, were applied to define traits linked to high-calorie intake. Samples from a human cohort confirmed potential lipidomic markers. Compared to those fed a standard growth diet, pigs fed a high-calorie diet showed an increased weight gain (13%), much higher adiposity (53%), hypertriacylglyceridemia and hypercholesterolemia in parallel to insulin resistance. This diet induced marked changes in the circulating lipidome, particularly in phosphatidylethanolamine-type molecules. Also, circulating specific diacylglycerol and monoacylglycerol contents correlated with visceral fat and intrahepatic triacylglycerol concentrations. Specific lipids associated with obesity in swine (mainly belonging to glycerophospholipid, triacylglyceride and sterol classes) were also linked with obesity traits in the human cohort, reinforcing the usefulness of the chosen approach. Interestingly, no overt inflammation in plasma or adipose tissue was evident in this model. The presented model is useful as a preclinical surrogate of prepubertal obesity in order to ascertain the pathophysiology interactions between energy intake and obesity development.

Gene expression and regulatory factors of the mechanistic target of rapamycin (mTOR) complex 1 predict mammalian longevity.

Species longevity varies significantly across animal species, but the underlying molecular mechanisms remain poorly understood. Recent studies and omics approaches suggest that phenotypic traits of longevity could converge in the mammalian target of rapamycin (mTOR) signalling pathway. The present study focuses on the comparative approach in heart tissue from 8 mammalian species with a ML ranging from 3.5 to 46 years. Gene expression, protein content, and concentration of regulatory metabolites of the mTOR complex 1 (mTORC1) were measured using droplet digital PCR, western blot, and mass spectrometry, respectively. Our results demonstrate (1) the existence of differences in species-specific gene expression and protein content of mTORC1, (2) that the achievement of a high longevity phenotype correlates with decreased and inhibited mTORC1, (3) a decreased content of mTORC1 activators in long-lived animals, and (4) that these differences are independent of phylogeny. Our findings, taken together, support an important role for mTORC1 downregulation in the evolution of long-lived mammals.

Metabolic adaptations in spontaneously immortalized PGC-1α knock-out mouse embryonic fibroblasts increase their oncogenic potential.

PGC-1α controls, to a large extent, the capacity of cells to respond to changing nutritional requirements and energetic demands. The key role of metabolic reprogramming in tumor development has highlighted the potential role of PGC-1α in cancer. To investigate how loss of PGC-1α activity in primary cells impacts the oncogenic characteristics of spontaneously immortalized cells, and the mechanisms involved, we used the classic 3T3 protocol to generate spontaneously immortalized mouse embryonic fibroblasts (iMEFs) from wild-type (WT) and PGC-1α knockout (KO) mice and analyzed their oncogenic potential in vivo and in vitro. We found that PGC-1α KO iMEFs formed larger and more proliferative primary tumors than WT counterparts, and fostered the formation of lung metastasis by B16 melanoma cells. These characteristics were associated with the reduced capacity of KO iMEFs to respond to cell contact inhibition, in addition to an increased ability to form colonies in soft agar, an enhanced migratory capacity, and a reduced growth factor dependence. The mechanistic basis of this phenotype is likely associated with the observed higher levels of nuclear ß-catenin and c-myc in KO iMEFs. Evaluation of the metabolic adaptations of the immortalized cell lines identified a decrease in oxidative metabolism and an increase in glycolytic flux in KO iMEFs, which were also more dependent on glutamine for their survival. Furthermore, glucose oxidation and tricarboxylic acid cycle forward flux were reduced in KO iMEF, resulting in the induction of compensatory anaplerotic pathways. Indeed, analysis of amino acid and lipid patterns supported the efficient use of tricarboxylic acid cycle intermediates to synthesize lipids and proteins to support elevated cell growth rates. All these characteristics have been observed in aggressive tumors and support a tumor suppressor role for PGC-1α, restraining metabolic adaptations in cancer.

Specific Metabolomics Adaptations Define a Differential Regional Vulnerability in the Adult Human Cerebral Cortex.

Brain neurons offer diverse responses to stresses and detrimental factors during development and aging, and as a result of both neurodegenerative and neuropsychiatric disorders. This multiplicity of responses can be ascribed to the great diversity among neuronal populations. Here we have determined the metabolomic profile of three healthy adult human brain regions-entorhinal cortex, hippocampus, and frontal cortex-using mass spectrometry-based technologies. Our results show the existence of a lessened energy demand, mitochondrial stress, and lower one-carbon metabolism (particularly restricted to the methionine cycle) specifically in frontal cortex. These findings, along with the better antioxidant capacity and lower mTOR signaling also seen in frontal cortex, suggest that this brain region is especially resistant to stress compared to the entorhinal cortex and hippocampus, which are more vulnerable regions. Globally, our results show the presence of specific metabolomics adaptations in three mature, healthy human brain regions, confirming the existence of cross-regional differences in cell vulnerability in the human cerebral cortex.