Imperial College London

DrAlexandrosSiskos

Faculty of MedicineDepartment of Surgery & Cancer

Research Associate
 
 
 
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AtriumSir Alexander Fleming BuildingSouth Kensington Campus

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Summary

 

Publications

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36 results found

Stratakis N, Siskos AP, Papadopoulou E, Nguyen AN, Zhao Y, Margetaki K, Lau C-HE, Coen M, Maitre L, Fernández-Barrés S, Agier L, Andrusaityte S, Basagaña X, Brantsaeter AL, Casas M, Fossati S, Grazuleviciene R, Heude B, McEachan RRC, Meltzer HM, Millett C, Rauber F, Robinson O, Roumeliotaki T, Borràs E, Sabidó E, Urquiza J, Vafeiadi M, Vineis P, Voortman T, Wright J, Conti DV, Vrijheid M, Keun HC, Chatzi Let al., 2021, Urinary metabolic biomarkers of diet quality in European children are associated with metabolic health

<jats:title>Abstract</jats:title><jats:p>Urinary metabolic profiling is a promising powerful tool to reflect dietary intake and can help understand metabolic alterations in response to diet quality. Here, we used <jats:sup>1</jats:sup>H-NMR spectroscopy in a multi-country study in European children (1147 children from 6 different cohorts) and identified a common panel of 4 urinary metabolites (hippurate, <jats:italic>N</jats:italic>-methylnicotinic acid, urea and sucrose) that was predictive of Mediterranean diet adherence (KIDMED) and ultra-processed food (UPF) consumption and also had higher capacity in discriminating children’s diet quality than that of established sociodemographic determinants. Further, we showed that the identified metabolite panel also reflected the associations of these diet quality indicators with C-peptide, a stable and accurate marker of insulin resistance and future risk of metabolic disease. This methodology enables objective assessment of dietary patterns in European child populations, complementary to traditional questionary methods, and can be used in future studies to evaluate diet quality. Moreover, this knowledge can provide mechanistic evidence of common biological pathways that characterize healthy and unhealthy dietary patterns, and diet-related molecular alterations that could associate to metabolic disease.</jats:p>

Journal article

Gallego-Paüls M, Hernández-Ferrer C, Bustamante M, Basagaña X, Barrera-Gómez J, Lau C-HE, Siskos AP, Vives-Usano M, Ruiz-Arenas C, Wright J, Slama R, Heude B, Casas M, Grazuleviciene R, Chatzi L, Borràs E, Sabidó E, Carracedo Á, Estivill X, Urquiza J, Coen M, Keun HC, González JR, Vrijheid M, Maitre Let al., 2021, Variability of multi-omics profiles in a population-based child cohort., BMC Medicine, Vol: 19, Pages: 1-16, ISSN: 1741-7015

BACKGROUND: Multiple omics technologies are increasingly applied to detect early, subtle molecular responses to environmental stressors for future disease risk prevention. However, there is an urgent need for further evaluation of stability and variability of omics profiles in healthy individuals, especially during childhood. METHODS: We aimed to estimate intra-, inter-individual and cohort variability of multi-omics profiles (blood DNA methylation, gene expression, miRNA, proteins and serum and urine metabolites) measured 6 months apart in 156 healthy children from five European countries. We further performed a multi-omics network analysis to establish clusters of co-varying omics features and assessed the contribution of key variables (including biological traits and sample collection parameters) to omics variability. RESULTS: All omics displayed a large range of intra- and inter-individual variability depending on each omics feature, although all presented a highest median intra-individual variability. DNA methylation was the most stable profile (median 37.6% inter-individual variability) while gene expression was the least stable (6.6%). Among the least stable features, we identified 1% cross-omics co-variation between CpGs and metabolites (e.g. glucose and CpGs related to obesity and type 2 diabetes). Explanatory variables, including age and body mass index (BMI), explained up to 9% of serum metabolite variability. CONCLUSIONS: Methylation and targeted serum metabolomics are the most reliable omics to implement in single time-point measurements in large cross-sectional studies. In the case of metabolomics, sample collection and individual traits (e.g. BMI) are important parameters to control for improved comparability, at the study design or analysis stage. This study will be valuable for the design and interpretation of epidemiological studies that aim to link omics signatures to disease, environmental exposures, or both.

Journal article

Dossus L, Kouloura E, Biessy C, Viallon V, Siskos AP, Dimou N, Rinaldi S, Merritt MA, Allen N, Fortner R, Kaaks R, Weiderpass E, Gram IT, Rothwell JA, Lécuyer L, Severi G, Schulze MB, Nøst TH, Crous-Bou M, Sánchez M-J, Amiano P, Colorado-Yohar SM, Gurrea AB, Schmidt JA, Palli D, Agnoli C, Tumino R, Sacerdote C, Mattiello A, Vermeulen R, Heath AK, Christakoudi S, Tsilidis KK, Travis RC, Gunter MJ, Keun HCet al., 2021, Prospective analysis of circulating metabolites and endometrial cancer risk, Gynecologic Oncology, ISSN: 0090-8258

AbstractBackgroundEndometrial cancer is strongly associated with obesity and dysregulation of metabolic factors such as estrogen and insulin signaling are causal risk factors for this malignancy. To identify additional novel metabolic pathways associated with endometrial cancer we performed metabolomic analyses on pre-diagnostic plasma samples from 853 case-control pairs from the European Prospective Investigation into Cancer and Nutrition (EPIC).MethodsA total of 129 metabolites (acylcarnitines, amino acids, biogenic amines, glycerophospholipids, hexoses, and sphingolipids) were measured by liquid chromatography-mass spectrometry. Conditional logistic regression estimated the associations of metabolites with endometrial cancer risk. An analysis focusing on clusters of metabolites using the bootstrap lasso method was also employed.ResultsAfter adjustment for body mass index, sphingomyelin [SM] C18:0 was positively (OR1SD: 1.18, 95% CI: 1.05–1.33), and glycine, serine, and free carnitine (C0) were inversely (OR1SD: 0.89, 95% CI: 0.80–0.99; OR1SD: 0.89, 95% CI: 0.79–1.00 and OR1SD: 0.91, 95% CI: 0.81–1.00, respectively) associated with endometrial cancer risk. Serine, C0 and two sphingomyelins were selected by the lasso method in >90% of the bootstrap samples. The ratio of esterified to free carnitine (OR1SD: 1.14, 95% CI: 1.02–1.28) and that of short chain to free acylcarnitines (OR1SD: 1.12, 95% CI: 1.00–1.25) were positively associated with endometrial cancer risk. Further adjustment for C-peptide or other endometrial cancer risk factors only minimally altered the results.ConclusionThese findings suggest that variation in levels of glycine, serine, SM C18:0 and free carnitine may represent specific pathways linked to endometrial cancer development. If causal, these pathways may offer novel targets for endometrial cancer prevention.

Journal article

Maitre L, Bustamante M, Hernández-Ferrer C, Thiel D, Lau C-H, Siskos A, Vives-Usano M, Ruiz-Arenas C, Robinson O, Mason D, Wright J, Cadiou S, Slama R, Heude B, Gallego-Paüls M, Casas M, Sunyer J, Papadopoulou EZ, Gutzkow KB, Andrusaityte S, Grazuleviciene R, Vafeiadi M, Chatzi L, Sakhi AK, Thomsen C, Tamayo I, Nieuwenhuijsen M, Urquiza J, Borràs E, Sabidó E, Quintela I, Carracedo Á, Estivill X, Coen M, González JR, Keun HC, Vrijheid Met al., 2021, Multi-omics signatures of the human early life exposome

<jats:title>Summary</jats:title><jats:p>Environmental exposures during early life play a critical role in life-course health, yet the molecular phenotypes underlying environmental effects on health are poorly understood. In the Human Early Life Exposome (HELIX) project, a multi-centre cohort of 1,301 mother-child pairs, we associated individual exposomes consisting of &gt;100 chemical, physical and lifestyle exposures assessed in pregnancy and childhood, with multi-omics profiles (methylome, transcriptome, metabolome and proteins) in childhood. We identified 1,170 associations, 249 in pregnancy and 921 in childhood, which revealed potential biological responses and sources of exposure. The methylome best captures the persistent influence of pregnancy exposures, including maternal smoking; while childhood exposures were associated with features from all omics layers, revealing novel signatures for indoor air quality, essential trace elements, endocrine disruptors and weather conditions. This study provides a unique resource (<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://helixomics.isglobal.org/">https://helixomics.isglobal.org/</jats:ext-link>) to guide future investigation on the biological effects of the early life exposome.</jats:p>

Journal article

Saavedra-Garcia P, Roman-Trufero M, Al-Sadah HA, Blighe K, Lopez-Jimenez E, Christoforou M, Penfold L, Capece D, Xiong X, Miao Y, Parzych K, Caputo V, Siskos AP, Encheva V, Liu Z, Thiel D, Kaiser MF, Piazza P, Chaidos A, Karadimitris A, Franzoso G, Snijder AP, Keun HC, Oyarzún DA, Barahona M, Auner Het al., 2021, Systems level profiling of chemotherapy-induced stress resolution in cancer cells reveals druggable trade-offs, Proceedings of the National Academy of Sciences of USA, Vol: 118, ISSN: 0027-8424

Cancer cells can survive chemotherapy-induced stress, but how they recover from it is not known.Using a temporal multiomics approach, we delineate the global mechanisms of proteotoxic stressresolution in multiple myeloma cells recovering from proteasome inhibition. Our observations definelayered and protracted programmes for stress resolution that encompass extensive changes acrossthe transcriptome, proteome, and metabolome. Cellular recovery from proteasome inhibitioninvolved protracted and dynamic changes of glucose and lipid metabolism and suppression ofmitochondrial function. We demonstrate that recovering cells are more vulnerable to specific insultsthan acutely stressed cells and identify the general control nonderepressable 2 (GCN2)-driven cellularresponse to amino acid scarcity as a key recovery-associated vulnerability. Using a transcriptomeanalysis pipeline, we further show that GCN2 is also a stress-independent bona fide target intranscriptional signature-defined subsets of solid cancers that share molecular characteristics. Thus,identifying cellular trade-offs tied to the resolution of chemotherapy-induced stress in tumour cellsmay reveal new therapeutic targets and routes for cancer therapy optimisation.

Journal article

Calvo-Serra B, Maitre L, Lau C-HE, Siskos AP, Gutzkow KB, Andrusaityte S, Casas M, Cadiou S, Chatzi L, Gonzalez JR, Grazuleviciene R, McEachan R, Slama R, Vafeiadi M, Wright J, Coen M, Vrijheid M, Keun HC, Escaramis G, Bustamante Met al., 2020, Urinary metabolite quantitative trait loci in children and their interaction with dietary factors, HUMAN MOLECULAR GENETICS, Vol: 29, Pages: 3830-3844, ISSN: 0964-6906

Journal article

Robinson O, 2020, Prenatal exposure to perfluoroalkyl substances associated with increased susceptibility to liver Injury in children, Hepatology, Vol: 72, Pages: 1758-1770, ISSN: 0270-9139

Background and AimsPer‐ and polyfluoroalkyl substances (PFAS) are widespread and persistent pollutants that have been shown to have hepatotoxic effects in animal models. However, human evidence is scarce. We evaluated how prenatal exposure to PFAS associates with established serum biomarkers of liver injury and alterations in serum metabolome in children.Approach and ResultsWe used data from 1,105 mothers and their children (median age, 8.2 years; interquartile range, 6.6‐9.1) from the European Human Early‐Life Exposome cohort (consisting of six existing population‐based birth cohorts in France, Greece, Lithuania, Norway, Spain, and the United Kingdom). We measured concentrations of perfluorooctane sulfonate, perfluorooctanoate, perfluorononanoate, perfluorohexane sulfonate, and perfluoroundecanoate in maternal blood. We assessed concentrations of alanine aminotransferase, aspartate aminotransferase, and gamma‐glutamyltransferase in child serum. Using Bayesian kernel machine regression, we found that higher exposure to PFAS during pregnancy was associated with higher liver enzyme levels in children. We also measured child serum metabolomics through a targeted assay and found significant perturbations in amino acid and glycerophospholipid metabolism associated with prenatal PFAS. A latent variable analysis identified a profile of children at high risk of liver injury (odds ratio, 1.56; 95% confidence interval, 1.21‐1.92) that was characterized by high prenatal exposure to PFAS and increased serum levels of branched‐chain amino acids (valine, leucine, and isoleucine), aromatic amino acids (tryptophan and phenylalanine), and glycerophospholipids (phosphatidylcholine [PC] aa C36:1 and Lyso‐PC a C18:1).ConclusionsDevelopmental exposure to PFAS can contribute to pediatric liver injury.

Journal article

Robinson O, 2020, In utero and childhood exposure to tobacco smoke and multi-layer molecular signatures in children, BMC Medicine, Vol: 18, Pages: 1-19, ISSN: 1741-7015

BackgroundThe adverse health effects of early life exposure to tobacco smoking have been widely reported. In spite of this, the underlying molecular mechanisms of in utero and postnatal exposure to tobacco smoke are only partially understood. Here, we aimed to identify multi-layer molecular signatures associated with exposure to tobacco smoke in these two exposure windows.MethodsWe investigated the associations of maternal smoking during pregnancy and childhood secondhand smoke (SHS) exposure with molecular features measured in 1203 European children (mean age 8.1 years) from the Human Early Life Exposome (HELIX) project. Molecular features, covering 4 layers, included blood DNA methylation and gene and miRNA transcription, plasma proteins, and sera and urinary metabolites.ResultsMaternal smoking during pregnancy was associated with DNA methylation changes at 18 loci in child blood. DNA methylation at 5 of these loci was related to expression of the nearby genes. However, the expression of these genes themselves was only weakly associated with maternal smoking. Conversely, childhood SHS was not associated with blood DNA methylation or transcription patterns, but with reduced levels of several serum metabolites and with increased plasma PAI1 (plasminogen activator inhibitor-1), a protein that inhibits fibrinolysis. Some of the in utero and childhood smoking-related molecular marks showed dose-response trends, with stronger effects with higher dose or longer duration of the exposure.ConclusionIn this first study covering multi-layer molecular features, pregnancy and childhood exposure to tobacco smoke were associated with distinct molecular phenotypes in children. The persistent and dose-dependent changes in the methylome make CpGs good candidates to develop biomarkers of past exposure. Moreover, compared to methylation, the weak association of maternal smoking in pregnancy with gene expression suggests different reversal rates and a methylation-based memory to

Journal article

McNeillis R, Greystoke A, Walton J, Bacon C, Keun H, Sitkos A, Petrides G, Leech N, Jenkinson F, Bowron A, Halford S, Plummer Ret al., 2020, A case of malignant hyperlactaemic acidosis appearing upon treatment with the mono-carboxylase transporter 1 inhibitor AZD3965, British Journal of Cancer, Vol: 122, Pages: 1141-1145, ISSN: 0007-0920

A 47-year-old man with metastatic melanoma presented with refractory hyperlactaemic acidosis following the first dose of the mono-carboxylase transporter 1 inhibitor AZD3965 within a "first time in man" clinical trial. The mechanism of the agent and the temporal relationship suggested that this event was potentially drug related and recruitment was suspended. However, urinary metabolomics showed extensive abnormalities even prior to drug administration, leading to investigations for an underlying metabolic disorder. The lack of clinical symptoms from the elevated lactate and low blood glucose suggested a diagnosis of "hyper-Warburgism", where the high tumour burden was associated with extensive glucose uptake and lactate efflux from malignant cells, and the subsequent impact on blood biochemistry. This was supported by an FDG-PET scan showing extensive glucose uptake in numerous metastases and lack of uptake in the brain. A review of the literature showed 16 case reports of "hyper-Warburgism" in non-haematological malignancies, none of them with melanoma, with most associated with a poor outcome. The patient was treated symptomatically, but died 2 months later. The development of AZD3965 continues with the exclusion of patients with elevated plasma lactate at screening added to the protocol as a safety measure. Trial identification number ClinicalTrials.Gov. NCT01791595.

Journal article

McNeillis R, Greystoke A, Walton J, Bacon C, Keun H, Siskos A, Petrides G, Leech N, Jenkinson F, Bowron A, Halford S, Plummer Ret al., 2020, A case of malignant hyperlactaemic acidosis appearing upon treatment with the mono-carboxylase transporter 1 inhibitor AZD3965 (Feb, 10.1038/s41416-020-0727-8, 2020), BRITISH JOURNAL OF CANCER, Vol: 122, Pages: 1272-1272, ISSN: 0007-0920

Journal article

Barnes EME, Xu Y, Benito A, Herendi L, Siskos AP, Aboagye EO, Keun H, Nijhuis Aet al., 2020, Lactic acidosis induces resistance to the pan-Akt inhibitor uprosertib in colon cancer cells, British Journal of Cancer, Vol: 122, Pages: 1298-1308, ISSN: 0007-0920

BackgroundAkt signalling regulates glycolysis and drives the Warburg effect in cancer, thus decreased glucose utilisation is a pharmacodynamic marker of Akt inhibition. However, cancer cells can utilise alternative nutrients to glucose for energy such as lactate, which is often elevated in tumours together with increased acidity. We therefore hypothesised that lactic acidosis may confer resistance to Akt inhibition.MethodsThe effect of the pan-Akt inhibitor uprosertib (GSK2141795), on HCT116 and LS174T colon cancer cells was evaluated in the presence and absence of lactic acid in vitro. Expression of downstream Akt signalling proteins was determined using a phosphokinase array and immunoblotting. Metabolism was assessed using 1H nuclear magnetic resonance spectroscopy, stable isotope labelling and gas chromatography-mass spectrometry.ResultsLactic acid-induced resistance to uprosertib was characterised by increased cell survival and reduced apoptosis. Uprosertib treatment reduced Akt signalling and glucose uptake irrespective of lactic acid supplementation. However, incorporation of lactate carbon and enhanced respiration was maintained in the presence of uprosertib and lactic acid. Inhibiting lactate transport or oxidative phosphorylation was sufficient to potentiate apoptosis in the presence of uprosertib.ConclusionsLactic acidosis confers resistance to uprosertib, which can be reversed by inhibiting lactate transport or oxidative metabolism.

Journal article

Georgiadis P, Gavriil M, Rantakokko P, Ladoukakis E, Botsivali M, Kelly RS, Bergdahl IA, Kiviranta H, Vermeulen RCH, Spaeth F, Hebbels DGAJ, Kleinjans JCS, de Kok TMCM, Palli D, Vineis P, Kyrtopoulos SA, EnviroGenomarkers consortiumet al., 2019, DNA methylation profiling implicates exposure to PCBs in the pathogenesis of B-cell chronic lymphocytic leukemia, Environment International, Vol: 126, Pages: 24-36, ISSN: 0160-4120

OBJECTIVES: To characterize the impact of PCB exposure on DNA methylation in peripheral blood leucocytes and to evaluate the corresponding changes in relation to possible health effects, with a focus on B-cell lymphoma. METHODS: We conducted an epigenome-wide association study on 611 adults free of diagnosed disease, living in Italy and Sweden, in whom we also measured plasma concentrations of 6 PCB congeners, DDE and hexachlorobenzene. RESULTS: We identified 650 CpG sites whose methylation correlates strongly (FDR < 0.01) with plasma concentrations of at least one PCB congener. Stronger effects were observed in males and in Sweden. This epigenetic exposure profile shows extensive and highly statistically significant overlaps with published profiles associated with the risk of future B-cell chronic lymphocytic leukemia (CLL) as well as with clinical CLL (38 and 28 CpG sites, respectively). For all these sites, the methylation changes were in the same direction for increasing exposure and for higher disease risk or clinical disease status, suggesting an etiological link between exposure and CLL. Mediation analysis reinforced the suggestion of a causal link between exposure, changes in DNA methylation and disease. Disease connectivity analysis identified multiple additional diseases associated with differentially methylated genes, including melanoma for which an etiological link with PCB exposure is established, as well as developmental and neurological diseases for which there is corresponding epidemiological evidence. Differentially methylated genes include many homeobox genes, suggesting that PCBs target stem cells. Furthermore, numerous polycomb protein target genes were hypermethylated with increasing exposure, an effect known to constitute an early marker of carcinogenesis. CONCLUSIONS: This study provides mechanistic evidence in support of a link between exposure to PCBs and the etiology of CLL and underlines the utility of omic profiling in the evaluation o

Journal article

Allen SP, Hall B, Castelli LM, Francis L, Woof R, Siskos AP, Kouloura E, Gray E, Thompson AG, Talbot K, Higginbottom A, Myszczynska M, Allen CF, Stopford MJ, Hemingway J, Bauer CS, Webster CP, De Vos KJ, Turner MR, Keun HC, Hautbergue GM, Ferraiuolo L, Shaw PJet al., 2019, Astrocyte adenosine deaminase loss increases motor neuron toxicity in amyotrophic lateral sclerosis, Brain, Vol: 142, Pages: 586-605, ISSN: 1460-2156

As clinical evidence supports a negative impact of dysfunctional energy metabolism on the disease progression in amyotrophic lateral sclerosis, it is vital to understand how the energy metabolic pathways are altered and whether they can be restored to slow disease progression. Possible approaches include increasing or rerouting catabolism of alternative fuel sources to supplement the glycolytic and mitochondrial pathways such as glycogen, ketone bodies and nucleosides. To analyse the basis of the catabolic defect in amyotrophic lateral sclerosis we used a novel phenotypic metabolic array. We profiled fibroblasts and induced neuronal progenitor-derived human induced astrocytes from C9orf72 amyotrophic lateral sclerosis patients compared to normal controls, measuring the rates of production of reduced nicotinamide adenine dinucleotides from 91 potential energy substrates. This approach shows for the first time that C9orf72 human induced astrocytes and fibroblasts have an adenosine to inosine deamination defect caused by reduction of adenosine deaminase, which is also observed in induced astrocytes from sporadic patients. Patient-derived induced astrocyte lines were more susceptible to adenosine-induced toxicity, which could be mimicked by inhibiting adenosine deaminase in control lines. Furthermore, adenosine deaminase inhibition in control induced astrocytes led to increased motor neuron toxicity in co-cultures, similar to the levels observed with patient derived induced astrocytes. Bypassing metabolically the adenosine deaminase defect by inosine supplementation was beneficial bioenergetically in vitro, increasing glycolytic energy output and leading to an increase in motor neuron survival in co-cultures with induced astrocytes. Inosine supplementation, in combination with modulation of the level of adenosine deaminase may represent a beneficial therapeutic approach to evaluate in patients with amyotrophic lateral sclerosis.

Journal article

Limonciel A, van Breda SG, Jiang X, Tredwell GD, Wilmes A, Aschauer L, Siskos AP, Sachinidis A, Keun HC, Kopp-Schneider A, de Kok TM, Kleinjans JCS, Jennings Pet al., 2018, Persistence of epigenomic effects after recovery from repeated treatment with two nephrocarcinogens, Frontiers in Genetics, Vol: 9, ISSN: 1664-8021

The discovery of the epigenetic regulation of transcription has provided a new source of mechanistic understanding to long lasting effects of chemicals. However, this information is still seldom exploited in a toxicological context and studies of chemical effect after washout remain rare. Here we studied the effects of two nephrocarcinogens on the human proximal tubule cell line RPTEC/TERT1 using high-content mRNA microarrays coupled with miRNA, histone acetylation (HA) and DNA methylation (DM) arrays and metabolomics during a 5-day repeat-dose exposure and 3 days after washout. The mycotoxin ochratoxin A (OTA) was chosen as a model compound for its known impact on HA and DM. The foremost effect observed was the modulation of thousands of mRNAs and histones by OTA during and after exposure. In comparison, the oxidant potassium bromate (KBrO3) had a milder impact on gene expression and epigenetics. However, there was no strong correlation between epigenetic modifications and mRNA changes with OTA while with KBrO3 the gene expression data correlated better with HA for both up- and down-regulated genes. Even when focusing on the genes with persistent epigenetic modifications after washout, only half were coupled to matching changes in gene expression induced by OTA, suggesting that while OTA causes a major effect on the two epigenetic mechanisms studied, these alone cannot explain its impact on gene expression. Mechanistic analysis confirmed the known activation of Nrf2 and p53 by KBrO3, while OTA inhibited most of the same genes, and genes involved in the unfolded protein response. A few miRNAs could be linked to these effects of OTA, albeit without clear contribution of epigenetics to the modulation of the pathways at large. Metabolomics revealed disturbances in amino acid balance, energy catabolism, nucleotide metabolism and polyamine metabolism with both chemicals. In conclusion, the large impact of OTA on transcription was confirmed at the mRNA level but also with

Journal article

Lau CH, Siskos AP, Maitre L, Robinson O, Athersuch TJ, Want EJ, Urquiza J, Casas M, Vafeiadi M, Roumeliotaki T, McEachan RRC, Azad R, Haug LS, Meltzer HM, Andrusaityte S, Petraviciene I, Grazuleviciene R, Thomsen C, Wright J, Slama R, Chatzi L, Vrijheid M, Keun HC, Coen Met al., 2018, Determinants of the urinary and serum metabolome in children from six European populations, BMC Medicine, Vol: 16, ISSN: 1741-7015

BackgroundEnvironment and diet in early life can affect development and health throughout the life course. Metabolic phenotyping of urine and serum represents a complementary systems-wide approach to elucidate environment–health interactions. However, large-scale metabolome studies in children combining analyses of these biological fluids are lacking. Here, we sought to characterise the major determinants of the child metabolome and to define metabolite associations with age, sex, BMI and dietary habits in European children, by exploiting a unique biobank established as part of the Human Early-Life Exposome project (http://www.projecthelix.eu).MethodsMetabolic phenotypes of matched urine and serum samples from 1192 children (aged 6–11) recruited from birth cohorts in six European countries were measured using high-throughput 1H nuclear magnetic resonance (NMR) spectroscopy and a targeted LC-MS/MS metabolomic assay (Biocrates AbsoluteIDQ p180 kit).ResultsWe identified both urinary and serum creatinine to be positively associated with age. Metabolic associations to BMI z-score included a novel association with urinary 4-deoxyerythronic acid in addition to valine, serum carnitine, short-chain acylcarnitines (C3, C5), glutamate, BCAAs, lysophosphatidylcholines (lysoPC a C14:0, lysoPC a C16:1, lysoPC a C18:1, lysoPC a C18:2) and sphingolipids (SM C16:0, SM C16:1, SM C18:1). Dietary-metabolite associations included urinary creatine and serum phosphatidylcholines (4) with meat intake, serum phosphatidylcholines (12) with fish, urinary hippurate with vegetables, and urinary proline betaine and hippurate with fruit intake. Population-specific variance (age, sex, BMI, ethnicity, dietary and country of origin) was better captured in the serum than in the urine profile; these factors explained a median of 9.0% variance amongst serum metabolites versus a median of 5.1% amongst urinary metabolites. Metabolic pathway correlations were identified, and concentrations of

Journal article

Maitre L, de Bont J, Casas M, Robinson O, Aasvang GM, Agier L, Andrušaitytė S, Ballester F, Basagaña X, Borràs E, Brochot C, Bustamante M, Carracedo A, de Castro M, Dedele A, Donaire-Gonzalez D, Estivill X, Evandt J, Fossati S, Giorgis-Allemand L, R Gonzalez J, Granum B, Grazuleviciene R, Bjerve Gützkow K, Småstuen Haug L, Hernandez-Ferrer C, Heude B, Ibarluzea J, Julvez J, Karachaliou M, Keun HC, Hjertager Krog N, Lau C-HE, Leventakou V, Lyon-Caen S, Manzano C, Mason D, McEachan R, Meltzer HM, Petraviciene I, Quentin J, Roumeliotaki T, Sabido E, Saulnier P-J, Siskos AP, Siroux V, Sunyer J, Tamayo I, Urquiza J, Vafeiadi M, van Gent D, Vives-Usano M, Waiblinger D, Warembourg C, Chatzi L, Coen M, van den Hazel P, Nieuwenhuijsen MJ, Slama R, Thomsen C, Wright J, Vrijheid Met al., 2018, Human Early Life Exposome (HELIX) study: a European population-based exposome cohort, BMJ Open, Vol: 8, ISSN: 2044-6055

Purpose Essential to exposome research is the collection of data on many environmental exposures from different domains in the same subjects. The aim of the Human Early Life Exposome (HELIX) study was to measure and describe multiple environmental exposures during early life (pregnancy and childhood) in a prospective cohort and associate these exposures with molecular omics signatures and child health outcomes. Here, we describe recruitment, measurements available and baseline data of the HELIX study populations.Participants The HELIX study represents a collaborative project across six established and ongoing longitudinal population-based birth cohort studies in six European countries (France, Greece, Lithuania, Norway, Spain and the UK). HELIX used a multilevel study design with the entire study population totalling 31 472 mother-child pairs, recruited during pregnancy, in the six existing cohorts (first level); a subcohort of 1301 mother-child pairs where biomarkers, omics signatures and child health outcomes were measured at age 6–11 years (second level) and repeat-sampling panel studies with around 150 children and 150 pregnant women aimed at collecting personal exposure data (third level).Findings to date Cohort data include urban environment, hazardous substances and lifestyle-related exposures for women during pregnancy and their offspring from birth until 6–11 years. Common, standardised protocols were used to collect biological samples, measure exposure biomarkers and omics signatures and assess child health across the six cohorts. Baseline data of the cohort show substantial variation in health outcomes and determinants between the six countries, for example, in family affluence levels, tobacco smoking, physical activity, dietary habits and prevalence of childhood obesity, asthma, allergies and attention deficit hyperactivity disorder.Future plans HELIX study results will inform on the early life exposome and its association with molecul

Journal article

Georgiadis P, Liampa I, Hebels DG, Krauskopf J, Chatziioannou A, Valavanis I, de Kok TMCM, Kleinjans JCS, Bergdahl IA, Melin B, Spaeth F, Palli D, Vermeulen RCH, Vlaanderen J, Chadeau-Hyam M, Vineis P, Kyrtopoulos SA, EnviroGenomarkers consortiumet al., 2017, Evolving DNA methylation and gene expression markers of B-cell chronic lymphocytic leukemia are present in pre-diagnostic blood samples more than 10 years prior to diagnosis., BMC Genomics, Vol: 18, ISSN: 1471-2164

BACKGROUND: B-cell chronic lymphocytic leukemia (CLL) is a common type of adult leukemia. It often follows an indolent course and is preceded by monoclonal B-cell lymphocytosis, an asymptomatic condition, however it is not known what causes subjects with this condition to progress to CLL. Hence the discovery of prediagnostic markers has the potential to improve the identification of subjects likely to develop CLL and may also provide insights into the pathogenesis of the disease of potential clinical relevance. RESULTS: We employed peripheral blood buffy coats of 347 apparently healthy subjects, of whom 28 were diagnosed with CLL 2.0-15.7 years after enrollment, to derive for the first time genome-wide DNA methylation, as well as gene and miRNA expression, profiles associated with the risk of future disease. After adjustment for white blood cell composition, we identified 722 differentially methylated CpG sites and 15 differentially expressed genes (Bonferroni-corrected p < 0.05) as well as 2 miRNAs (FDR < 0.05) which were associated with the risk of future CLL. The majority of these signals have also been observed in clinical CLL, suggesting the presence in prediagnostic blood of CLL-like cells. Future CLL cases who, at enrollment, had a relatively low B-cell fraction (<10%), and were therefore less likely to have been suffering from undiagnosed CLL or a precursor condition, showed profiles involving smaller numbers of the same differential signals with intensities, after adjusting for B-cell content, generally smaller than those observed in the full set of cases. A similar picture was obtained when the differential profiles of cases with time-to-diagnosis above the overall median period of 7.4 years were compared with those with shorted time-to-disease. Differentially methylated genes of major functional significance include numerous genes that encode for transcription factors, especially members of the homeobox family, while

Journal article

Maitre L, Lau C-HE, Vizcaino E, Robinson O, Casas M, Siskos AP, Want EJ, Athersuch T, Slama R, Vrijheid M, Keun HC, Coen Met al., 2017, Assessment of metabolic phenotypic variability in children's urine using H-1 NMR spectroscopy, Scientific Reports, Vol: 7, ISSN: 2045-2322

The application of metabolic phenotyping in clinical and epidemiological studies is limited by a poor understanding of inter-individual, intra-individual and temporal variability in metabolic phenotypes. Using 1H NMR spectroscopy we characterised short-term variability in urinary metabolites measured from 20 children aged 8–9 years old. Daily spot morning, night-time and pooled (50:50 morning and night-time) urine samples across six days (18 samples per child) were analysed, and 44 metabolites quantified. Intraclass correlation coefficients (ICC) and mixed effect models were applied to assess the reproducibility and biological variance of metabolic phenotypes. Excellent analytical reproducibility and precision was demonstrated for the 1H NMR spectroscopic platform (median CV 7.2%). Pooled samples captured the best inter-individual variability with an ICC of 0.40 (median). Trimethylamine, N-acetyl neuraminic acid, 3-hydroxyisobutyrate, 3-hydroxybutyrate/3-aminoisobutyrate, tyrosine, valine and 3-hydroxyisovalerate exhibited the highest stability with over 50% of variance specific to the child. The pooled sample was shown to capture the most inter-individual variance in the metabolic phenotype, which is of importance for molecular epidemiology study design. A substantial proportion of the variation in the urinary metabolome of children is specific to the individual, underlining the potential of such data to inform clinical and exposome studies conducted early in life.

Journal article

Chatziioannou A, Georgiadis P, Hebels DG, Liampa I, Valavanis I, Bergdahl IA, Johansson A, Palli D, Chadeau-Hyam M, Siskos AP, Keun H, Botsivali M, de Kok TMCM, Perez AE, Kleinjans JCS, Vineis P, Kyrtopoulos SAet al., 2017, Blood-based omic profiling supports female susceptibility to tobacco smoke-induced cardiovascular diseases, SCIENTIFIC REPORTS, Vol: 7, ISSN: 2045-2322

We recently reported that differential gene expression and DNA methylation profiles in blood leukocytes of apparently healthy smokers predicts with remarkable efficiency diseases and conditions known to be causally associated with smoking, suggesting that blood-based omic profiling of human populations may be useful for linking environmental exposures to potential health effects. Here we report on the sex-specific effects of tobacco smoking on transcriptomic and epigenetic features derived from genome-wide profiling in white blood cells, identifying 26 expression probes and 92 CpG sites, almost all of which are affected only in female smokers. Strikingly, these features relate to numerous genes with a key role in the pathogenesis of cardiovascular disease, especially thrombin signaling, including the thrombin receptors on platelets F2R (coagulation factor II (thrombin) receptor; PAR1) and GP5 (glycoprotein 5), as well as HMOX1 (haem oxygenase 1) and BCL2L1 (BCL2-like 1) which are involved in protection against oxidative stress and apoptosis, respectively. These results are in concordance with epidemiological evidence of higher female susceptibility to tobacco-induced cardiovascular disease and underline the potential of blood-based omic profiling in hazard and risk assessment.

Journal article

Sood D, Johnson N, Jain P, Siskos AP, Bennett M, Gilham C, Busana MC, Peto J, dos-Santos-Silva I, Keun HC, Fletcher Oet al., 2017, CYP3A7*1C allele is associated with reduced levels of 2-hydroxylation pathway oestrogen metabolites, British Journal of Cancer, Vol: 116, Pages: 382-388, ISSN: 1532-1827

background: Endogenous sex hormones are well-established risk factors for breast cancer; the contribution of specific oestrogen metabolites (EMs) and/or ratios of specific EMs is less clear. We have previously identified a CYP3A7*1C allele that is associated with lower urinary oestrone (E1) levels in premenopausal women. The purpose of this analysis was to determine whether this allele was associated with specific pathway EMs.methods: We measured successfully 12 EMs in mid-follicular phase urine samples from 30 CYP3A7*1C carriers and 30 non-carriers using HPLC-MS/MS.results: In addition to having lower urinary E1 levels, CYP3A7*1C carriers had significantly lower levels of four of the 2-hydroxylation pathway EMs that we measured (2-hydroxyestrone, P=1.1 × 10−12; 2-hydroxyestradiol, P=2.7 × 10−7; 2-methoxyestrone, P=1.9 × 10−12; and 2-methoxyestradiol, P=0.0009). By contrast, 16α-hydroxylation pathway EMs were slightly higher in carriers and significantly so for 17-epiestriol (P=0.002).conclusions: The CYP3A7*1C allele is associated with a lower urinary E1 levels, a more pronounced reduction in 2-hydroxylation pathway EMs and a lower ratio of 2-hydroxylation:16α-hydroxylation EMs in premenopausal women. To further characterise the association between parent oestrogens, EMs and subsequent risk of breast cancer, characterisation of additional genetic variants that influence oestrogen metabolism and large prospective studies of a broad spectrum of EMs will be required.

Journal article

Siskos AP, Jain P, Romisch-Margl W, Bennet M, Achaintre D, Asad Y, Marney L, Richardson L, Koulman A, Griffin JL, Raynaud F, Scalbert A, Adamski J, Prehn C, Keun HCet al., 2016, Interlaboratory reproducibility of a targeted metabolomics platform for analysis of human serum and plasma, Analytical Chemistry, Vol: 89, Pages: 656-665, ISSN: 1086-4377

A critical question facing the field of metabolomics is whether data obtained from different centers can be effectively compared and combined. An important aspect of this is the interlaboratory precision (reproducibility) of the analytical protocols used. We analyzed human samples in six laboratories using different instrumentation but a common protocol (the AbsoluteIDQ p180 kit) for the measurement of 189 metabolites via liquid chromatography (LC) or flow injection analysis (FIA) coupled to tandem mass spectrometry (MS/MS). In spiked quality control (QC) samples 82% of metabolite measurements had an interlaboratory precision of <20%, while 83% of averaged individual laboratory measurements were accurate to within 20%. For 20 typical biological samples (serum and plasma from healthy individuals) the median interlaboratory coefficient of variation (CV) was 7.6%, with 85% of metabolites exhibiting a median interlaboratory CV of <20%. Precision was largely independent of the type of sample (serum or plasma) or the anticoagulant used but was reduced in a sample from a patient with dyslipidaemia. The median interlaboratory accuracy and precision of the assay for standard reference plasma (NIST SRM 1950) were 107% and 6.7%, respectively. Likely sources of irreproducibility were the near limit of detection (LOD) typical abundance of some metabolites and the degree of manual review and optimization of peak integration in the LC–MS/MS data after acquisition. Normalization to a reference material was crucial for the semi-quantitative FIA measurements. This is the first interlaboratory assessment of a widely used, targeted metabolomics assay illustrating the reproducibility of the protocol and how data generated on different instruments could be directly integrated in large-scale epidemiological studies.

Journal article

Perng W, Oken E, Roumeliotaki T, Sood D, Siskos AP, Chalkiadaki G, Dermitzaki E, Vafeiadi M, Kyrtopoulos S, Kogevinas M, Keun HC, Chatzi Let al., 2016, Leptin, acylcarnitine metabolites and development of adiposity in the Rhea mother-child cohort in Crete, Greece., Obesity Science and Practice, Vol: 2, Pages: 471-476, ISSN: 2055-2238

OBJECTIVE: This study aims to investigate relations of serum leptin at age 4 with development of adiposity and linear growth during 3 years of follow-up among 75 Greek children and to identify serum metabolites associated with leptin at age 4 and to characterize their associations with adiposity gain and linear growth. METHODS: Linear regression models that accounted for maternal age, education and gestational weight gain and child's age and sex were used to examine associations of leptin and leptin-associated metabolites measured at age 4 with indicators of adiposity and linear growth at age 7. RESULTS: Each 1-unit increment in natural log-(ln)-transformed leptin corresponded with 0.33 (95% CI: 0.10, 0.55) units greater body mass index-for-age z-score gain during follow-up. Likewise, higher levels of the leptin-associated metabolites methylmalonyl-carnitine and glutaconyl-carnitine corresponded with 0.14 (95% CI: 0.01, 0.27) and 0.07 (95% CI: -0.01, 0.16) units higher body mass index-for-age z-score gain, respectively. These relationships did not differ by sex or baseline weight status and were independent of linear growth. CONCLUSIONS: These findings suggest that leptin, methylmalonyl-carnitine and possibly glutaconyl-carnitine are associated with weight gain during early childhood. Future studies are warranted to confirm these findings in other populations.

Journal article

Georgiadis P, Hebels DG, Valavanis I, Liampa I, Bergdahl IA, Johansson A, Palli D, Chadeau-Hyam M, Chatziioannou A, Jennen DGJ, Krauskopf J, Jetten MJ, Kleinjans JCS, Vineis P, Kyrtopoulos SAet al., 2016, Omics for prediction of environmental health effects: blood leukocyte-based cross-omic profiling reliably predicts diseases associated with tobacco smoking, Scientific Reports, Vol: 6, ISSN: 2045-2322

The utility of blood-based omic profiles for linking environmental exposures to their potential health effects was evaluated in 649 individuals, drawn from the general population, in relation to tobacco smoking, an exposure with well-characterised health effects. Using disease connectivity analysis, we found that the combination of smoking-modified, genome-wide gene (including miRNA) expression and DNA methylation profiles predicts with remarkable reliability most diseases and conditions independently known to be causally associated with smoking (indicative estimates of sensitivity and positive predictive value 94% and 84%, respectively). Bioinformatics analysis reveals the importance of a small number of smoking-modified, master-regulatory genes and suggest a central role for altered ubiquitination. The smoking-induced gene expression profiles overlap significantly with profiles present in blood cells of patients with lung cancer or coronary heart disease, diseases strongly associated with tobacco smoking. These results provide proof-of-principle support to the suggestion that omic profiling in peripheral blood has the potential of identifying early, disease-related perturbations caused by toxic exposures and may be a useful tool in hazard and risk assessment.

Journal article

Valbuena GN, Rizzardini M, Cimini S, Siskos AP, Bendotti C, Cantoni L, Keun HCet al., 2015, Metabolomic Analysis Reveals Increased Aerobic Glycolysis and Amino Acid Deficit in a Cellular Model of Amyotrophic Lateral Sclerosis, Molecular Neurobiology, Vol: 53, Pages: 2222-2240, ISSN: 1559-1182

Defects in energy metabolism are potential pathogenic mechanisms in amyotrophic lateral sclerosis (ALS), a rapidly fatal disease with no cure. The mechanisms through which this occurs remain elusive and their understanding may prove therapeutically useful. We used metabolomics and stable isotope tracers to examine metabolic changes in a well-characterized cell model of familial ALS, the motor neuronal NSC-34 line stably expressing human wild-type Cu/Zn superoxide dismutase (wtSOD1) or mutant G93A (G93ASOD1). Our findings indicate that wt and G93ASOD1 expression both enhanced glucose metabolism under serum deprivation. However, in wtSOD1 cells, this phenotype increased supply of amino acids for protein and glutathione synthesis, while in G93ASOD1 cells it was associated with death, aerobic glycolysis, and a broad dysregulation of amino acid homeostasis. Aerobic glycolysis was mainly due to induction of pyruvate dehydrogenase kinase 1. Our study thus provides novel insight into the role of deranged energy metabolism as a cause of poor adaptation to stress and a promoter of neural cell damage in the presence of mutant SOD1. Furthermore, the metabolic alterations we report may help explain why mitochondrial dysfunction and impairment of the endoplasmic reticulum stress response are frequently seen in ALS.

Journal article

Miller JA, Pappan K, Thompson PA, Want EJ, Siskos AP, Keun HC, Wulff J, Hu C, Lang JE, Chow H-HSet al., 2015, Plasma Metabolomic Profiles of Breast Cancer Patients after Short-term Limonene Intervention, CANCER PREVENTION RESEARCH, Vol: 8, ISSN: 1940-6207

Journal article

Chatziioannou AN, Siskos AP, Loxas D, Kavatzas N, Agrogiannis G, Fokas D, Malagari K, Kostomitsopoulos NG, Tsigkou O, Tamvakopoulos Cet al., 2013, Transarterial Embolization with Sorafenib in Animal Livers: A Pharmacokinetics Study, JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY, Vol: 24, Pages: 1657-1663, ISSN: 1051-0443

Journal article

Katsila T, Siskos AP, Tamvakopoulos C, 2012, Peptide and protein drugs: The study of their metabolism and catabolism by mass spectrometry, MASS SPECTROMETRY REVIEWS, Vol: 31, Pages: 110-133, ISSN: 0277-7037

Journal article

Anderson R, Franch A, Castell M, Perez-Cano FJ, Braeuer R, Pohlers D, Gajda M, Siskos AP, Katsila T, Tamvakopoulos C, Rauchhaus U, Panzner S, Kinne RWet al., 2010, Liposomal encapsulation enhances and prolongs the anti-inflammatory effects of water-soluble dexamethasone phosphate in experimental adjuvant arthritis, Arthritis Research and Therapy, Vol: 12, Pages: 1-15, ISSN: 1478-6354

IntroductionThe objective of this study was to evaluate the efficacy of intravenous (i.v.) injection of liposomally encapsulated dexamethasone phosphate (DxM-P) in comparison to free DxM-P in rats with established adjuvant arthritis (AA). This study focused on polyethylene glycol (PEG)-free liposomes, to minimize known allergic reactions caused by neutral PEG-modified (PEG-ylated) liposomes.MethodsEfficacy was assessed clinically and histologically using standard scores. Non-specific and specific immune parameters were monitored. Activation of peritoneal macrophages was analyzed via cytokine profiling. Pharmacokinetics/biodistribution of DxM in plasma, synovial membrane, spleen and liver were assessed via mass spectrometry.ResultsLiposomal DxM-P (3 × 1 mg/kg body weight; administered intravenously (i.v.) on Days 14, 15 and 16 of AA) suppressed established AA, including histological signs, erythrocyte sedimentation rate, white blood cell count, circulating anti-mycobacterial IgG, and production of interleukin-1beta (IL-1β) and IL-6 by peritoneal macrophages. The suppression was strong and long-lasting. The clinical effects of liposomal DxM-P were dose-dependent for dosages between 0.01 and 1.0 mg/kg. Single administration of 1 mg/kg liposomal DxM-P and 3 × 1 mg/kg of free DxM-P showed comparable effects consisting of a partial and transient suppression. Moreover, the effects of medium-dose liposomal DxM-P (3 × 0.1 mg/kg) were equal (in the short term) or superior (in the long term) to those of high-dose free DxM-P (3 × 1 mg/kg), suggesting a potential dose reduction by a factor between 3 and 10 by liposomal encapsulation. For at least 48 hours after the last injection, the liposomal drug achieved significantly higher levels in plasma, synovial membrane, spleen and liver than the free drug.ConclusionsThis new PEG-free formulation of macrophage-targeting liposomal DxM-P considerably reduces the dose and/or frequency required to treat AA, wi

Journal article

Siskos AP, 2010, The biosynthesis of Soraphen A.

Journal article

Siskos AP, Katsila T, Balafas E, Kostomitsopoulos N, Tamvakopoulos Cet al., 2009, Simultaneous Absolute Quantification of the Glucose-Dependent Insulinotropic Polypeptides GIP(1-42) and GIP(3-42) in Mouse Plasma by LC/ESI-MS/MS: Preclinical Evaluation of DP-IV Inhibitors, JOURNAL OF PROTEOME RESEARCH, Vol: 8, Pages: 3487-3496, ISSN: 1535-3893

Journal article

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