Association between childhood obesity, trace elements, and heavy metals: Recent discoveries and future perspectives.

Trace elements and heavy metals play pivotal roles in health status by regulating a myriad of vital biological functions. Abnormal metal homeostasis has been linked to a constellation of pathogenic complications, including oxidative stress, inflammatory processes, dyslipidemia, and impaired insulin-mediated metabolism of carbohydrates, thereby increasing the odds of developing childhood obesity and related comorbidities. Herein, we provide a comprehensive revision of recent literature on the association between childhood obesity, trace elements, and heavy metals. Further, we emphasize on the crucial importance of addressing the influence that interindividual variability factors (e.g., sex, age, genetic determinants, concomitance of comorbidities, and environmental factors) may have in modulating the susceptibility to disease development. Altogether, this review article represents a concise guide to better understand the involvement of metals in childhood obesity pathogenesis and discusses future needs with the aim of establishing robust biomarkers in the context of precision medicine.

Somatostatin: a possible mediator of the long-term effects of experimental vertical gastrectomy on glucose metabolism in rats?

BACKGROUND: Sleeve gastrectomy (SG) is one of the most commonly performed bariatric surgeries. SG treats type 2 diabetes mellitus better than several drugs. The mechanisms that underlie this phenomenon are not clear. This study proposed that somatostatin (SST) isoforms SST-14 and SST-28 are key in the carbohydrate after SG. METHODS: Surgeries were performed on 3 groups of Wistar rats: the fasting, surgery control, and SG groups. Plasma levels of glucose, insulin, SST-14, and SST-28 were measured at 2 survival periods after surgery. Islet SST receptor (SSTR) and cell populations were studied. We performed a pasireotide (SST-28 analogue) infusion assay in another group of rats to confirm the influence of SST-28 plasma levels on the delta-cell population. RESULTS: This study found an elevation in the insulin response after SG in animals but a decrease in the insulin response over the long term with a loss of beta-cell mass. An increase in duodenal SST-28-producing cells in the duodenum and a loss of pancreatic SST-14-producing cells were observed after SG in animals but not in controls. The expression of SSTR type 5 in delta-cell populations from each group and the ability of the pasireotide infusion assay to decrease the delta-cell population indicated the effect of SST-28 plasma levels on delta-cell maintenance. CONCLUSION: After SG initiates a compensatory response in the duodenum, beta-cell mass is depleted after loss of the brake that regulates SST-14 at the paracrine level in a nonobese, normoglycemic rat model. This was an experimental model, with no clinical translation to the human clinic, with a preliminary importance regarding new pathophysiologic perspectives or pathways.

Mass Spectrometry-Based Metabolomics Multi-platform for Alzheimer's Disease Research.

The integration of complementary analytical platforms is nowadays the most common strategy for comprehensive metabolomics analysis of complex biological systems. In this chapter, we describe methods and tips for the application of a mass spectrometry multi-platform in Alzheimer's disease research, based on the combination of direct mass spectrometry and orthogonal hyphenated approaches, namely, reversed-phase ultrahigh-performance liquid chromatography and gas chromatography. These procedures have been optimized for the analysis of multiple biological samples from human patients and transgenic animal models, including blood serum, various brain regions (e.g., hippocampus, cortex, cerebellum, striatum, olfactory bulbs), and other peripheral organs (e.g., liver, kidney, spleen, thymus).

QComics: Recommendations and Guidelines for Robust, Easily Implementable and Reportable Quality Control of Metabolomics Data.

The implementation of quality control strategies is crucial to ensure the reproducibility, accuracy, and meaningfulness of metabolomics data. However, this pivotal step is often overlooked within the metabolomics workflow and frequently relies on the use of nonstandardized and poorly reported protocols. To address current limitations in this respect, we have developed QComics, a robust, easily implementable and reportable method for monitoring and controlling data quality. The protocol operates in various sequential steps aimed to (i) correct for background noise and carryover, (ii) detect signal drifts and "out-of-control" observations, (iii) deal with missing data, (iv) remove outliers, (v) monitor quality markers to identify samples affected by improper collection, preprocessing, or storage, and (vi) assess overall data quality in terms of precision and accuracy. Notably, this tool considers important issues often neglected along quality control, such as the need of separately handling missing values and truly absent data to avoid losing relevant biological information, as well as the large impact that preanalytical factors may elicit on metabolomics results. Altogether, the guidelines compiled in QComics might contribute to establishing gold standard recommendations and best practices for quality control within the metabolomics community.

Parental obesity predisposes to exacerbated metabolic and inflammatory disturbances in childhood obesity within the framework of an altered profile of trace elements.

BACKGROUND: Family history of obesity is known to increase the odds of developing childhood obesity in the offspring, but its influence in underlying molecular complications remains unexplored. SUBJECTS/METHODS: Here, we investigated a population-based cohort comprising children with obesity, with and without parental obesity (PO+, N = 20; PO-, N = 29), and lean healthy children as controls (N = 30), from whom plasma and erythrocyte samples were collected to characterize their multi-elemental profile, inflammatory status, as well as carbohydrate and lipid metabolisms. RESULTS: We found parental obesity to be associated with unhealthier outcomes in children, as reflected in increased blood insulin levels and reduced insulin sensitivity, unfavorable lipid profile, and pro-inflammatory milieu. This was accompanied by moderate alterations in the content of trace elements, including increased copper-to-zinc ratios and iron deficiency in circulation, as well as metal accumulation within erythrocytes. CONCLUSIONS: Therefore, we hypothesize that family history of obesity could be an important risk factor in modulating the characteristic multi-elemental alterations behind childhood obesity, which in turn could predispose to boost related comorbidities and metabolic complications.

Childhood obesity, metabolic syndrome, and oxidative stress: microRNAs go on stage.

The incidence of childhood obesity and metabolic syndrome has grown notably in the last years, becoming major public health burdens in developed countries. Nowadays, oxidative stress is well-recognized to be closely associated with the onset and progression of several obesity-related complications within the framework of a complex crosstalk involving other intertwined pathogenic events, such as inflammation, insulin disturbances, and dyslipidemia. Thus, understanding the molecular basis behind these oxidative dysregulations could provide new approaches for the diagnosis, prevention, and treatment of childhood obesity and associated disorders. In this respect, the transcriptomic characterization of miRNAs bares great potential because of their involvement in post-transcriptional modulation of genetic expression. Herein, we provide a comprehensive literature revision gathering state-of-the-art research into the association between childhood obesity, metabolic syndrome, and miRNAs. We put special emphasis on the potential role of miRNAs in modulating obesity-related pathogenic events, with particular focus on oxidative stress.

Altered insulin secretion dynamics relate to oxidative stress and inflammasome activation in children with obesity and insulin resistance.

BACKGROUND: Insulin resistance (IR) is considered the main driver of obesity related metabolic complications, and is related to oxidative stress and inflammation, which in turn promote each other. There is currently no specific definition of IR in children, rather, that for adult population is used by pediatric endocrinologists instead. Altered insulin secretion dynamics are associated with worse metabolic profiles and type 2 diabetes mellitus development, thus we aimed to test whether insulin response relates to oxidative stress and inflammation in children. METHODS: We conducted a case-control study, including 132 children classified as follows: 33 children without obesity (Lean); 42 with obesity but no IR according to the American Diabetes Association criteria for adults (OBIR-); 25 with obesity and IR and an early insulin response to an oral glucose tolerance test (OGTT) (EP-OBIR +); 32 with obesity, IR, and a late insulin peak (LP-OBIR +); and studied variables associated with lipid and carbohydrate metabolism, oxidative stress, inflammation and inflammasome activation. RESULTS: The measured parameters of children with obesity, IR, and an early insulin response were similar to those of children with obesity but without IR. It was late responders who presented an impaired antioxidant system and elevated oxidative damage in erythrocytes and plasma, and inflammasome activation at their white blood cells, despite lower classical inflammation markers. Increased uric acid levels seems to be one of the underlying mechanisms for inflammasome activation. CONCLUSIONS: It is insulin response to an OGTT that identifies children with obesity suffering oxidative stress and inflammasome activation more specifically. Uric acid could be mediating this pathological inflammatory response by activating NLRP3 in peripheral blood mononuclear cells.

The role of glucagon after bariatric/metabolic surgery: much more than an "anti-insulin" hormone.

The biological activity of glucagon has recently been proposed to both stimulate hepatic glucose production and also include a paradoxical insulinotropic effect, which could suggest a new role of glucagon in the pathophysiology type 2 diabetes mellitus (T2DM). An insulinotropic role of glucagon has been observed after bariatric/metabolic surgery that is mediated through the GLP-1 receptor on pancreatic beta cells. This effect appears to be modulated by other members of the proglucagon family, playing a key role in the beneficial effects and complications of bariatric/metabolic surgery. Glucagon serves a dual role after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). In addition to maintaining blood glucose levels, glucagon exhibits an insulinotropic effect, suggesting that glucagon has a more complex function than simply an "anti-insulin hormone".

Integrative metabolomics science in Alzheimer's disease: Relevance and future perspectives.

Alzheimer's disease (AD) is determined by various pathophysiological mechanisms starting 10-25 years before the onset of clinical symptoms. As multiple functionally interconnected molecular/cellular pathways appear disrupted in AD, the exploitation of high-throughput unbiased omics sciences is critical to elucidating the precise pathogenesis of AD. Among different omics, metabolomics is a fast-growing discipline allowing for the simultaneous detection and quantification of hundreds/thousands of perturbed metabolites in tissues or biofluids, reproducing the fluctuations of multiple networks affected by a disease. Here, we seek to critically depict the main metabolomics methodologies with the aim of identifying new potential AD biomarkers and further elucidating AD pathophysiological mechanisms. From a systems biology perspective, as metabolic alterations can occur before the development of clinical signs, metabolomics - coupled with existing accessible biomarkers used for AD screening and diagnosis - can support early disease diagnosis and help develop individualized treatment plans. Presently, the majority of metabolomic analyses emphasized that lipid metabolism is the most consistently altered pathway in AD pathogenesis. The possibility that metabolomics may reveal crucial steps in AD pathogenesis is undermined by the difficulty in discriminating between the causal or epiphenomenal or compensatory nature of metabolic findings.

Metal Homeostasis and Exposure in Distinct Phenotypic Subtypes of Insulin Resistance among Children with Obesity.

BACKGROUND: Trace elements and heavy metals have proven pivotal roles in childhood obesity and insulin resistance. However, growing evidence suggests that insulin resistance could encompass distinct phenotypic subtypes. METHODS: Herein, we performed a comprehensive metallomics characterization of plasma samples from children and adolescents with obesity and concomitant insulin resistance, who were stratified as early (N = 17, 11.4 ± 2.4 years), middle (N = 16, 11.8 ± 1.9 years), and late (N = 33, 11.7 ± 2.0 years) responders according to the insulin secretion profile in response to an oral glucose tolerance test. To this end, we employed a high-throughput method aimed at determining the biodistribution of various essential and toxic elements by analyzing total metal contents, metal-containing proteins, and labile metal species. RESULTS: Compared with the early responders, participants with delayed glucose-induced hyperinsulinemia showed a worsened insulin resistance (HOMA-IR, 4.5 vs. 3.8) and lipid profile (total cholesterol, 160 vs. 144 mg/dL; LDL-cholesterol, 99 vs. 82 mg/dL), which in turn was accompanied by sharpened disturbances in the levels of plasmatic proteins containing chromium (4.8 vs. 5.1 µg/L), cobalt (0.79 vs. 1.2 µg/L), lead (0.021 vs. 0.025 µg/L), and arsenic (0.077 vs. 0.17 µg/L). A correlation analysis demonstrated a close inter-relationship among these multielemental perturbations and the characteristic metabolic complications occurring in childhood obesity, namely impaired insulin-mediated metabolism of carbohydrates and lipids. CONCLUSIONS: These findings highlight the crucial involvement that altered metal homeostasis and exposure may have in regulating insulin signaling, glucose metabolism, and dyslipidemia in childhood obesity.

Trace elements as potential modulators of puberty-induced amelioration of oxidative stress and inflammation in childhood obesity.

Although puberty is known to influence obesity progression, the molecular mechanisms underlying the role of sexual maturation in obesity-related complications remains largely unexplored. Here, we delve into the impact of puberty on the most relevant pathogenic hallmarks of obesity, namely oxidative stress and inflammation, and their association with trace element blood status. To this end, we studied a well-characterized observational cohort comprising prepubertal (N = 46) and pubertal (N = 48) children with obesity. From all participants, plasma and erythrocyte samples were collected and subjected to metallomics analysis and determination of classical biomarkers of oxidative stress and inflammation. Besides the expected raise of sexual hormones, pubertal children displayed better inflammatory and oxidative control, as reflected by lower levels of C-reactive protein and oxidative damage markers, as well as improved antioxidant defense. This was in turn accompanied by a healthier multielemental profile, with increased levels of essential elements involved in the antioxidant system and metabolic control (metalloproteins containing zinc, molybdenum, selenium, and manganese) and decreased content of potentially deleterious species (total copper, labile free iron). Therefore, our findings suggest that children with obesity have an exacerbated inflammatory and oxidative damage at early ages, which could be ameliorated during pubertal development by the action of trace element-mediated buffering mechanisms.

Sexually dimorphic metal alterations in childhood obesity are modulated by a complex interplay between inflammation, insulin, and sex hormones.

Although growing evidence points to a pivotal role of perturbed metal homeostasis in childhood obesity, sexual dimorphisms in this association have rarely been investigated. In this study, we applied multi-elemental analysis to plasma and erythrocyte samples from an observational cohort comprising children with obesity, with and without insulin resistance, and healthy control children. Furthermore, a wide number of variables related to carbohydrate and lipid metabolism, inflammation, and sex hormones were also determined. Children with obesity, regardless of sex and insulin resistance status, showed increased plasma copper-to-zinc ratios. More interestingly, obesity-related erythroid alterations were found to be sex-dependent, with increased contents of iron, zinc, and copper being exclusively detected among female subjects. Our findings suggest that a sexually dimorphic hormonal dysregulation in response to a pathological cascade involving inflammatory processes and hyperinsulinemia could be the main trigger of this female-specific intracellular sequestration of trace elements. Therefore, the present study highlights the relevance of genotypic sex as a susceptibility factor influencing the pathogenic events behind childhood obesity, thereby opening the door to develop sex-personalized approaches in the context of precision medicine.

Analysis and Annotation of Phospholipids by Mass Spectrometry-Based Metabolomics.

Phospholipids are essential components of membrane lipid bilayers and serve as precursors of multiple signaling molecules, so alterations in their homeostasis are associated with the pathogenesis of numerous diseases. In this context, the application of mass spectrometry-based metabolomics has demonstrated great potential to comprehensively characterize the human phospholipidome. In this chapter, we describe an untargeted method for the determination of phospholipids and other related metabolites in a variety of biological matrices, including plasma/serum, erythrocytes, and tissues, based on the combination of high-throughput direct mass spectrometry fingerprinting and subsequent profiling by ultra-high-performance reversed-phase liquid chromatography coupled to mass spectrometry. Furthermore, we also review the characteristic fragmentation patterns of phospholipids with the aim of providing simple guidelines for their straightforward annotation.

Untargeted Metabolomics Based on Liquid Chromatography-Mass Spectrometry for the Analysis of Plasma and Erythrocyte Samples in Childhood Obesity.

The circulating metabolome of human peripheral blood provides valuable information to investigate the molecular mechanisms underlying the development of diseases and to discover candidate biomarkers. In particular, erythrocytes have been proposed as potential systemic indicators of the metabolic and redox status of the organism. To accomplish wide-coverage metabolomics analysis, the combination of complementary analytical techniques is necessary to manage the physicochemical complexity of the human metabolome. Herein, we describe an untargeted metabolomics method to capture the plasmatic and erythroid metabolomes based on ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry, combining reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography. The method provides comprehensive metabolomics fingerprinting of plasma and erythrocyte samples, thereby enabling the elucidation of the distinctive metabolic disturbances behind childhood obesity and associated comorbidities, such as insulin resistance.

Characterization of the Plasmatic and Erythroid Multielemental Biodistribution in Childhood Obesity Using a High-Throughput Method for Size Fractionation of Metal Species.

In this chapter, we describe a metallomics method based on protein precipitation under non-denaturing conditions and further analysis by inductively coupled plasma mass spectrometry for high-throughput metal speciation in plasma and erythrocyte samples. This methodology enables to study the total multielemental profile of these biological matrices, as well as to quantify the metal fractions conforming the metallometabolome and the metalloproteome. Furthermore, the analytical coverage comprises several essential and toxic metal elements, namely aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, lithium, manganese, molybdenum, nickel, lead, selenium, vanadium, and zinc. Altogether, the metallomics method here proposed represents an excellent approach to comprehensively characterize the metal biodistribution in human peripheral blood, which would enable to decipher the role of metal homeostasis in health and disease, and particularly in childhood obesity.

Altered Metal Homeostasis Associates with Inflammation, Oxidative Stress, Impaired Glucose Metabolism, and Dyslipidemia in the Crosstalk between Childhood Obesity and Insulin Resistance.

Metals are redox-active substances that participate in central biological processes and may be involved in a multitude of pathogenic events. However, considering the inconsistencies reported in the literature, further research is crucial to disentangle the role of metal homeostasis in childhood obesity and comorbidities using well-characterized cohorts and state-of-the-art analytical methods. To this end, we studied an observational population comprising children with obesity and insulin resistance, children with obesity without insulin resistance, and healthy control children. A multi-elemental approach based on the size-fractionation of metal species was applied to quantify the total content of various essential and toxic elements in plasma and erythrocyte samples, and to simultaneously investigate the metal fractions conforming the metalloproteome and the labile metal pool. The most important disturbances in childhood obesity were found to be related to elevated circulating copper levels, decreased content of plasmatic proteins containing chromium, cobalt, iron, manganese, molybdenum, selenium, and zinc, as well as the sequestration of copper, iron, and selenium within erythrocytes. Interestingly, these metal disturbances were normally exacerbated among children with concomitant insulin resistance, and in turn were associated to other characteristic pathogenic events, such as inflammation, oxidative stress, abnormal glucose metabolism, and dyslipidemia. Therefore, this study represents one-step further towards a better understanding of the involvement of metals in the crosstalk between childhood obesity and insulin resistance.

Catalase post-translational modifications as key targets in the control of erythrocyte redox homeostasis in children with obesity and insulin resistance.

Insulin resistance (IR) is the most common metabolic disturbance in children with obesity. Children with obesity and insulin resistance (ObIR+) display a detriment in erythroid antioxidant defenses, caused by an impaired catalase activity and the increase in oxidative and pro-inflammatory markers. Therefore, erythrocytes from ObRI+ are more vulnerable to any oxidative stress elicitor. Since catalase is one of the erythrocytes' first antioxidant defenses, we intended to delve into the mechanisms underlying catalase's impaired activity. Given the lack of cellular organelles in erythrocytes, which prevents protein synthesis, we aimed study catalase post-translational modifications (PTMs) as targets of pro-inflammatory and pro-oxidant status of these cells in children with obesity and IR. Catalase levels of O-glycosylation, tyrosine nitration and S-glutathionylation were analyzed by Western blotting (WB) using immunoprecipitated catalase (IP-CAT) from erythrocyte lysates. Furthermore, Catalase was also identified by LC-MS/MS after isolation and enrichment of erythrocyte nitrosated proteins with a biotin switch approach. The results obtained suggest that catalase inhibition seen in children with obesity is partly due to the increase in the S-nitrosation of the enzyme. Indeed, exogenous administration of nitric oxide (NO) to cultured erythrocytes resulted in a decrease in catalase activity in all groups. Signals of other PTMs (O-glycosylation, Tyr-nitration and S-glutathionylation) were also detected in the erythrocyte catalase in every groups, although levels of catalase O-glycosylation and S-glutathionylation decreased in ObIR+. No evidence of differences in Tyr-nitration of catalase levels were found among groups. The study again highlights the role of erythrocytes as sensors of the inflammatory and pro-oxidant response to which these cells are subjected in children with obesity and insulin resistance.

Exploring the association between circulating trace elements, metabolic risk factors, and the adherence to a Mediterranean diet among children and adolescents with obesity.

Diet is one of the most important modifiable lifestyle factors for preventing and treating obesity. In this respect, the Mediterranean diet (MD) has proven to be a rich source of a myriad of micronutrients with positive repercussions on human health. Herein, we studied an observational cohort of children and adolescents with obesity (N = 26) to explore the association between circulating blood trace elements and the degree of MD adherence, as assessed through the KIDMED questionnaire. Participants with higher MD adherence showed better glycemic/insulinemic control and a healthier lipid profile, as well as raised plasma levels of selenium, zinc, cobalt, molybdenum, and arsenic, and increased erythroid content of selenium. Interestingly, we found that these MD-related mineral alterations were closely correlated with the characteristic metabolic complications behind childhood obesity, namely hyperglycemia, hyperinsulinemia, and dyslipidemia (p < 0.05, |r| > 0.35). These findings highlight the pivotal role that dietary trace elements may play in the pathogenesis of obesity and related disorders.

Inhibition of the NLRP3 inflammasome improves lifespan in animal murine model of Hutchinson-Gilford Progeria.

Inflammation is a hallmark of aging and accelerated aging syndromes such as Hutchinson-Gilford progeria syndrome (HGPS). In this study, we present evidence of increased expression of the components of the NLRP3 inflammasome pathway in HGPS skin fibroblasts, an outcome that was associated with morphological changes of the nuclei of the cells. Lymphoblasts from HGPS patients also showed increased basal levels of NLRP3 and caspase 1. Consistent with these results, the expression of caspase 1 and Nlrp3, but not of the other inflammasome receptors was higher in the heart and liver of Zmpste24-/- mice, which phenocopy the human disease. These data were further corroborated in LmnaG609G/G609G mice, another HGPS animal model. We also showed that pharmacological inhibition of the NLRP3 inflammasome by its selective inhibitor, MCC950, improved cellular phenotype, significantly extended the lifespan of progeroid animals, and reduced inflammasome-dependent inflammation. These findings suggest that inhibition of the NLRP3 inflammasome is a potential therapeutic approach for the treatment of HGPS.

Mechanistic Insights into Alzheimer's Disease Unveiled through the Investigation of Disturbances in Central Metabolites and Metabolic Pathways.

Hydrophilic metabolites are closely involved in multiple primary metabolic pathways and, consequently, play an essential role in the onset and progression of multifactorial human disorders, such as Alzheimer's disease. This review article provides a comprehensive revision of the literature published on the use of mass spectrometry-based metabolomics platforms for approaching the central metabolome in Alzheimer's disease research, including direct mass spectrometry, gas chromatography-mass spectrometry, hydrophilic interaction liquid chromatography-mass spectrometry, and capillary electrophoresis-mass spectrometry. Overall, mounting evidence points to profound disturbances that affect a multitude of central metabolic pathways, such as the energy-related metabolism, the urea cycle, the homeostasis of amino acids, fatty acids and nucleotides, neurotransmission, and others.