Professional Education


  • Master of Science, Universidad Politecnica de Valencia (UPV) (2013)
  • Bachelor of Science, Universidad Politecnica de Valencia (UPV) (2013)
  • Doctor of Science, Maastricht University (2017)
  • Master of Science, Cranfield Institute Of Technology (2013)

All Publications


  • Genes associated with Parkinson's disease respond to increasing polychlorinated biphenyl levels in the blood of healthy females ENVIRONMENTAL POLLUTION Bohler, S., Krauskopf, J., Espin-Perez, A., Gebel, S., Palli, D., Rantakokko, P., Kiviranta, H., Kyrtopoulos, S. A., Balling, R., Kleinjans, J. 2019; 250: 107–17

    Abstract

    Polychlorinated biphenyls (PCBs) are a class of widespread environmental pollutants, commonly found in human blood, that have been suggested to be linked to the occurrence of sporadic Parkinson's disease (PD). It has been reported that some non-coplanar PCBs accumulate in the brains of female PD patients. To improve our understanding of the association between PCB exposure and PD risk we have applied whole transcriptome gene expression analysis in blood cells from 594 PCB-exposed subjects (369 female, 225 male). Interestingly, we observe that in females, blood levels of non-coplanar PCBs appear to be associated with expression levels of PD-specific genes. However, no such association was detected in males. Among the 131 PD-specific genes affected, 39 have been shown to display similar changes in expression levels in the substantia nigra of deceased PD patients. Especially among the down-regulated genes, transcripts of genes involved in neurotransmitter vesicle-related functions were predominant.

    View details for DOI 10.1016/j.envpol.2019.04.005

    View details for Web of Science ID 000471088200013

    View details for PubMedID 30991279

  • The Cord Blood Insulin and Mitochondrial DNA Content Related Methylome FRONTIERS IN GENETICS Reimann, B., Janssen, B. G., Alfano, R., Ghantous, A., Espin-Perez, A., de Koko, T. M., Saenen, N. D., Cox, B., Robinson, O., Chadeau-Hyam, M., Penders, J., Herceg, Z., Vineis, P., Nawrot, T. S., Plusquin, M. 2019; 10
  • Identification of Sex-Specific Transcriptome Responses to Polychlorinated Biphenyls (PCBs) SCIENTIFIC REPORTS Espin-Perez, A., Hebels, D. J., Kiviranta, H., Rantakokko, P., Georgiadis, P., Botsivali, M., Bergdahl, I. A., Palli, D., Spath, F., Johansson, A., Chadeau-Hyam, M., Kyrtopoulos, S. A., Kleinjans, J. S., de Kok, T. M. 2019; 9: 746

    Abstract

    PCBs are classified as xenoestrogens and carcinogens and their health risks may be sex-specific. To identify potential sex-specific responses to PCB-exposure we established gene expression profiles in a population study subdivided into females and males. Gene expression profiles were determined in a study population consisting of 512 subjects from the EnviroGenomarkers project, 217 subjects who developed lymphoma and 295 controls were selected in later life. We ran linear mixed models in order to find associations between gene expression and exposure to PCBs, while correcting for confounders, in particular distribution of white blood cells (WBC), as well as random effects. The analysis was subdivided according to sex and development of lymphoma in later life. The changes in gene expression as a result of exposure to the six studied PCB congeners were sex- and WBC type specific. The relatively large number of genes that are significantly associated with PCB-exposure in the female subpopulation already indicates different biological response mechanisms to PCBs between the two sexes. The interaction analysis between different PCBs and WBCs provides only a small overlap between sexes. In males, cancer-related pathways and in females immune system-related pathways are identified in association with PCBs and WBCs. Future lymphoma cases and controls for both sexes show different responses to the interaction of PCBs with WBCs, suggesting a role of the immune system in PCB-related cancer development.

    View details for DOI 10.1038/s41598-018-37449-y

    View details for Web of Science ID 000456554600185

    View details for PubMedID 30679748

    View details for PubMedCentralID PMC6346099

  • The Cord Blood Insulin and Mitochondrial DNA Content Related Methylome. Frontiers in genetics Reimann, B. n., Janssen, B. G., Alfano, R. n., Ghantous, A. n., Espín-Pérez, A. n., de Kok, T. M., Saenen, N. D., Cox, B. n., Robinson, O. n., Chadeau-Hyam, M. n., Penders, J. n., Herceg, Z. n., Vineis, P. n., Nawrot, T. S., Plusquin, M. n. 2019; 10: 325

    Abstract

    Mitochondrial dysfunction seems to play a key role in the etiology of insulin resistance. At birth, a link has already been established between mitochondrial DNA (mtDNA) content and insulin levels in cord blood. In this study, we explore shared epigenetic mechanisms of the association between mtDNA content and insulin levels, supporting the developmental origins of this link. First, the association between cord blood insulin and mtDNA content in 882 newborns of the ENVIRONAGE birth cohort was assessed. Cord blood mtDNA content was established via qPCR, while cord blood levels of insulin were determined using electrochemiluminescence immunoassays. Then the cord blood DNA methylome and transcriptome were determined in 179 newborns, using the human 450K methylation Illumina and Agilent Whole Human Genome 8 × 60 K microarrays, respectively. Subsequently, we performed an epigenome-wide association study (EWAS) adjusted for different maternal and neonatal variables. Afterward, we focused on the 20 strongest associations based on p-values to assign transcriptomic correlates and allocate corresponding pathways employing the R packages ReactomePA and RDAVIDWebService. On the regional level, we examined differential methylation using the DMRcate and Bumphunter packages in R. Cord blood mtDNA content and insulin were significantly correlated (r = 0.074, p = 0.028), still showing a trend after additional adjustment for maternal and neonatal variables (p = 0.062). We found an overlap of 33 pathways which were in common between the association with cord blood mtDNA content and insulin levels, including pathways of neurodevelopment, histone modification, cytochromes P450 (CYP)-metabolism, and biological aging. We further identified a DMR annotated to Repulsive Guidance Molecule BMP Co-Receptor A (RGMA) linked to cord blood insulin as well as mtDNA content. Metabolic variation in early life represented by neonatal insulin levels and mtDNA content might reflect or accommodate alterations in neurodevelopment, histone modification, CYP-metabolism, and aging, indicating etiological origins in epigenetic programming. Variation in metabolic hormones at birth, reflected by molecular changes, might via these alterations predispose children to metabolic diseases later in life. The results of this study may provide important markers for following targeted studies.

    View details for PubMedID 31031804

    View details for PubMedCentralID PMC6474284

  • Short-term transcriptome and microRNAs responses to exposure to different air pollutants in two population studies ENVIRONMENTAL POLLUTION Espin-Perez, A., Krauskopf, J., Chadeau-Hyam, M., van Veldhoven, K., Chung, F., Cullinan, P., Piepers, J., van Herwijnen, M., Kubesch, N., Carrasco-Turigas, G., Nieuwenhuijsen, M., Vineis, P., Kleinjans, J. S., de Kok, T. M. 2018; 242: 182–90

    Abstract

    Diesel vehicle emissions are the major source of genotoxic compounds in ambient air from urban areas. These pollutants are linked to risks of cardiovascular diseases, lung cancer, respiratory infections and adverse neurological effects. Biological events associated with exposure to some air pollutants are widely unknown but applying omics techniques may help to identify the molecular processes that link exposure to disease risk. Most data on health risks are related to long-term exposure, so the aim of this study is to investigate the impact of short-term exposure (two hours) to air pollutants on the blood transcriptome and microRNA expression levels. We analyzed transcriptomics and microRNA expression using microarray technology on blood samples from volunteers participating in studies in London, the Oxford Street cohort, and, in Barcelona, the TAPAS cohort. Personal exposure levels measurements of particulate matter (PM10, PM2.5), ultrafine particles (UFPC), nitrogen oxides (NO2, NO and NOx), black carbon (BC) and carbon oxides (CO and CO2) were registered for each volunteer. Associations between air pollutant levels and gene/microRNA expression were evaluated using multivariate normal models (MVN). MVN-models identified compound-specific expression of blood cell genes and microRNAs associated with air pollution despite the low exposure levels, the short exposure periods and the relatively small-sized cohorts. Hsa-miR-197-3p, hsa-miR-29a-3p, hsa-miR-15a-5p, hsa-miR-16-5p and hsa-miR-92a-3p are found significantly expressed in association with exposures. These microRNAs target also relevant transcripts, indicating their potential relevance in the research of omics-biomarkers responding to air pollution. Furthermore, these microRNAs are also known to be associated with diseases previously linked to air pollution exposure including several cancers such lung cancer and Alzheimer's disease. In conclusion, we identified in this study promising compound-specific mRNA and microRNA biomarkers after two hours of exposure to low levels of air pollutants during two hours that suggest increased cancer risks.

    View details for DOI 10.1016/j.envpol.2018.06.051

    View details for Web of Science ID 000446150300021

    View details for PubMedID 29980036

  • Comparison of statistical methods and the use of quality control samples for batch effect correction in human transcriptome data PLOS ONE Espin-Perez, A., Portier, C., Chadeau-Hyam, M., van Veldhoven, K., Kleinjans, J. S., de Kok, T. M. 2018; 13 (8): e0202947

    Abstract

    Batch effects are technical sources of variation introduced by the necessity of conducting gene expression analyses on different dates due to the large number of biological samples in population-based studies. The aim of this study is to evaluate the performances of linear mixed models (LMM) and Combat in batch effect removal. We also assessed the utility of adding quality control samples in the study design as technical replicates. In order to do so, we simulated gene expression data by adding "treatment" and batch effects to a real gene expression dataset. The performances of LMM and Combat, with and without quality control samples, are assessed in terms of sensitivity and specificity while correcting for the batch effect using a wide range of effect sizes, statistical noise, sample sizes and level of balanced/unbalanced designs. The simulations showed small differences among LMM and Combat. LMM identifies stronger relationships between big effect sizes and gene expression than Combat, while Combat identifies in general more true and false positives than LMM. However, these small differences can still be relevant depending on the research goal. When any of these methods are applied, quality control samples did not reduce the batch effect, showing no added value for including them in the study design.

    View details for DOI 10.1371/journal.pone.0202947

    View details for Web of Science ID 000443388900053

    View details for PubMedID 30161168

    View details for PubMedCentralID PMC6117018

  • Blood transcriptional and microRNA responses to short-term exposure to disinfection by-products in a swimming pool ENVIRONMENT INTERNATIONAL Espin-Perez, A., Font-Ribera, L., van Veldhoven, K., Krauskopf, J., Portengen, L., Chadeau-Hyam, M., Vermeulen, R., Grimalt, J. O., Villanueva, C. M., Vineis, P., Kogevinas, M., Kleinjans, J. C., de Kok, T. M. 2018; 110: 42–50

    Abstract

    Swimming in a chlorinated pool results in high exposure levels to disinfection by-products (DBPs), which have been associated with an increased risk of bladder cancer.By studying molecular responses at the blood transcriptome level we examined the biological processes associated with exposure to these compounds.Whole-genome gene expression and microRNA analysis was performed on blood samples collected from 43 volunteers before and 2h after 40min swimming in an indoor chlorinated pool (PISCINAII study). Exposure to THMs was measured in exhaled breath. Heart rate and kcal expenditure were measured as proxies for physical activity. Associations between exposure levels and gene expression were assessed using multivariate normal models (MVN), correcting for age, body mass index and sex. A Bonferroni threshold at 5% was applied.MVN-models for the individual exposures identified 1778 genes and 23 microRNAs that were significantly associated with exposure to at least one DBP. Due to co-linearity it was not possible to statistically disentangle responses to DBP exposure from those related to physical activity. However, after eliminating previously reported transcripts associated with physical activity a large number of hits remained associated with DBP exposure. Among those, 9 were linked with bladder and 31 with colon cancer. Concordant microRNA/mRNA expressions were identified in association with DBP exposure for hsa-mir-22-3p and hsa-miR-146a-5p and their targets RCOR1 and TLR4, both related to colon cancer in association with DBP exposure.Short-term exposure to low levels of DBPs shows genomics responses that may be indicative of increased cancer risk.

    View details for DOI 10.1016/j.envint.2017.10.003

    View details for Web of Science ID 000414872800005

    View details for PubMedID 29122314

  • Distinct genotype-dependent differences in transcriptome responses in humans exposed to environmental carcinogens CARCINOGENESIS Espin-Perez, A., de Kok, T. M., Jennen, D. J., Hendrickx, D. M., De Coster, S., Schoeters, G., Baeyens, W., van Larebeke, N., Kleinjans, J. S. 2015; 36 (10): 1154–61

    Abstract

    Considering genetic variability in population studies focusing on the health risk assessment of exposure to environmental carcinogens may provide improved insights in individual environmental cancer risks. Therefore, the current study aims to determine the impact of genetic polymorphisms on the relationship between exposure and gene expression, by identifying exposure-dependently coregulated genes and genetic pathways. Statistical analysis based on mixed models, was performed to relate gene expression data from 134 subjects to exposure measurements of multiple carcinogens, 28 polymorphisms, age, sex and biomarkers of cancer risk. We evaluated the combined exposure to cadmium, lead, polychlorinated biphenyls, p,p'-dichlorodiphenyldichloroethylene, hexachlorobenzene and 1-OH-pyrene, and the outcome was biologically interpreted by using ConsensusPathDB, thereby focusing on carcinogenesis-related pathways. We found generic and carcinogenesis-related pathways deregulated in both sexes, but males showed a stronger transcriptome response than females. We highlighted NOTCH1, CBR1, ITGB3, ITGA4, ADI1, HES1, NCOA2 and SMARCA2 in view of their direct link with cancer development. Two of these, NOTCH1 and ITGB3, are also known to respond to PCBs and cadmium chloride exposure in rodents and to lead in humans. Subjects carrying a high number of risk alleles appear more responsive to combined carcinogen exposure with respect to the induced expression of some of these cancer-related genes, which may be indicative of increased cancer risk as a consequence of environmental factors.

    View details for DOI 10.1093/carcin/bgv111

    View details for Web of Science ID 000362850200009

    View details for PubMedID 26233959

  • Global MicroRNA Analysis in Primary Hepatocyte Cultures PROTOCOLS IN IN VITRO HEPATOCYTE RESEARCH Krauskopf, J., Espin-Perez, A., Kleinjans, J. C., de Kok, T. M., Vinken, M., Rogiers 2015; 1250: 241–50

    Abstract

    MicroRNAs are small non-coding molecules that regulate gene expression and in return affect diverse biological functions, including those involved in toxicity and development of disease. Recent evidence suggests that microRNAs play an important role in liver pathologies, like viral hepatitis, alcoholic liver, hepatocellular carcinoma, or drug-induced liver injury. Furthermore, numerous studies demonstrated the high potential of microRNAs as promising non-invasive biomarkers of liver disease or as relevant targets for therapeutic treatment. This chapter describes a method for global microRNA analysis of primary hepatocytes by high-throughput sequencing. The method comprises the isolation of high-quality total RNA, analysis of microRNA sequencing data, and the validation of the findings by reverse transcriptase quantitative polymerase chain reaction analysis.

    View details for DOI 10.1007/978-1-4939-2074-7_17

    View details for Web of Science ID 000364020600018

    View details for PubMedID 26272147