Advancing human health risk assessment

Acknowledgements: The European Food Safety Authority (EFSA) and authors wish to thank the participants of the break‐out session ‘Advancing risk assessment science – Human health’ at EFSA's third Scientific Conference ‘Science, Food and Society’ (Parma, Italy, 18–21 September 2018) for their active and valuable contributions to the discussion. We also thank Hans Verhagen for carefully proofreading it.Peer reviewedPublisher PD

Analysis of shared heritability in common disorders of the brain

ience, this issue p. eaap8757 Structured Abstract INTRODUCTION Brain disorders may exhibit shared symptoms and substantial epidemiological comorbidity, inciting debate about their etiologic overlap. However, detailed study of phenotypes with different ages of onset, severity, and presentation poses a considerable challenge. Recently developed heritability methods allow us to accurately measure correlation of genome-wide common variant risk between two phenotypes from pools of different individuals and assess how connected they, or at least their genetic risks, are on the genomic level. We used genome-wide association data for 265,218 patients and 784,643 control participants, as well as 17 phenotypes from a total of 1,191,588 individuals, to quantify the degree of overlap for genetic risk factors of 25 common brain disorders. RATIONALE Over the past century, the classification of brain disorders has evolved to reflect the medical and scientific communities' assessments of the presumed root causes of clinical phenomena such as behavioral change, loss of motor function, or alterations of consciousness. Directly observable phenomena (such as the presence of emboli, protein tangles, or unusual electrical activity patterns) generally define and separate neurological disorders from psychiatric disorders. Understanding the genetic underpinnings and categorical distinctions for brain disorders and related phenotypes may inform the search for their biological mechanisms. RESULTS Common variant risk for psychiatric disorders was shown to correlate significantly, especially among attention deficit hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder (MDD), and schizophrenia. By contrast, neurological disorders appear more distinct from one another and from the psychiatric disorders, except for migraine, which was significantly correlated to ADHD, MDD, and Tourette syndrome. We demonstrate that, in the general population, the personality trait neuroticism is significantly correlated with almost every psychiatric disorder and migraine. We also identify significant genetic sharing between disorders and early life cognitive measures (e.g., years of education and college attainment) in the general population, demonstrating positive correlation with several psychiatric disorders (e.g., anorexia nervosa and bipolar disorder) and negative correlation with several neurological phenotypes (e.g., Alzheimer's disease and ischemic stroke), even though the latter are considered to result from specific processes that occur later in life. Extensive simulations were also performed to inform how statistical power, diagnostic misclassification, and phenotypic heterogeneity influence genetic correlations. CONCLUSION The high degree of genetic correlation among many of the psychiatric disorders adds further evidence that their current clinical boundaries do not reflect distinct underlying pathogenic processes, at least on the genetic level. This suggests a deeply interconnected nature for psychiatric disorders, in contrast to neurological disorders, and underscores the need to refine psychiatric diagnostics. Genetically informed analyses may provide important "scaffolding" to support such restructuring of psychiatric nosology, which likely requires incorporating many levels of information. By contrast, we find limited evidence for widespread common genetic risk sharing among neurological disorders or across neurological and psychiatric disorders. We show that both psychiatric and neurological disorders have robust correlations with cognitive and personality measures. Further study is needed to evaluate whether overlapping genetic contributions to psychiatric pathology may influence treatment choices. Ultimately, such developments may pave the way toward reduced heterogeneity and improved diagnosis and treatment of psychiatric disorders

Application of in vitro neurotoxicity testing for regulatory purposes: Symposium III summary and research needs

Prediction of neurotoxic effects is a key feature in the toxicological profile of many compounds and therefore is required by regulatory testing schemes. Nowadays neurotoxicity assessment required by the OECD and EC test guidelines is based solely on in vivo testing, evaluating mainly effects on neurobehavior and neuropathology, which is expensive, time consuming and unsuitable for screening large number of chemicals. Additionally, such in vivo tests are not always sensitive enough to predict human neurotoxicity and often do not provide information that facilitates regulatory decision-making processes. Incorporation of alternative tests (in vitro testing, computational modelling, QSARs, grouping, read-across, etc.) in screening strategies would speed up the rate at which compound knowledge and mechanistic data are available and the information obtained could be used in the refinement of future in vivo studies to facilitate predictions of neurotoxicity. On 1st June 2007, the European Commission legislation concerning registration, evaluation and authorisation of chemicals (REACH) has entered into force. REACH addresses one of the key issues for chemicals in Europe, the lack of publicly available safety data sheets. It outlines a plan to test approximately 30,000 existing substances. These chemicals are currently produced in volumes greater than 1 ton/year and the essential data on the human health and ecotoxicological effects are lacking. It is estimated that approximately 3.9 million test animals (including 2.6 million vertebrates) (Hartung T, Bremer S, Casati S, Coecke S, Corvi R, Fortnaer S, et al. ECVAM's response to the changing political environment for alternatives: consequences of the European Union chemicals and cosmetics policies. ATLA 2003;31:473–81) would be necessary to fulfill the requirements of REACH if the development and establishment of alternative methods is not accepted by regulatory authorities. In an effort to reduce animal use and testing costs within this tonnage band, the European Commission has advocated the use of alternative approaches. Neurotoxicity testing is not directly addressed within REACH, however when alerts are observed based on organ specific toxicity studies then neurotoxicity assessment has to be performed. This session at the 11th International Neurotoxicology Association Meeting provided a forum to openly discuss and debate the potential of in vitro testing strategies that could be relevant for neurotoxicity evaluation in the context of regulatory requirements. The EU FP6 project A-Cute-Tox was presented as an example of a possible in vitro testing strategy for prediction of human acute systemic toxicity. Other presentations focused on the characterization of the available in vitro models (cell lines and primary culture) and neuronal specific endpoints, with a special emphasis on electrical activity, metabonomics and modulation of vesicular neurotransmitter release as possible neuronal endpoints relevant for in vitro neurotoxicity testing. Finally, it was underlined that in vitro systems (strategies) that have the potential to be applied for neurotoxicity assessment have to be formally validated under standardised conditions that have been recognised by national and international validation bodies.Work by the authors was supported by the following grants: FIS PI061212 (Ministry of Health, Spain), the EU Integrated Project LSHB-CT-2004-512051 (CS), the European Union (DEVNERTOX-FOOD-CT2003-506143) and MIUR (PRIN 2004) (LGC) and by the State of Mecklenburg-Vorpommern and European Community (ERDF).Peer reviewe

Putative adverse outcome pathways relevant to neurotoxicity

Anna K. Bal-Price et al.© 2015 Informa Healthcare USA. The Adverse Outcome Pathway (AOP) framework provides a template that facilitates understanding of complex biological systems and the pathways of toxicity that result in adverse outcomes (AOs). The AOP starts with an molecular initiating event (MIE) in which a chemical interacts with a biological target(s), followed by a sequential series of KEs, which are cellular, anatomical, and/or functional changes in biological processes, that ultimately result in an AO manifest in individual organisms and populations. It has been developed as a tool for a knowledge-based safety assessment that relies on understanding mechanisms of toxicity, rather than simply observing its adverse outcome. A large number of cellular and molecular processes are known to be crucial to proper development and function of the central (CNS) and peripheral nervous systems (PNS). However, there are relatively few examples of well-documented pathways that include causally linked MIEs and KEs that result in adverse outcomes in the CNS or PNS. As a first step in applying the AOP framework to adverse health outcomes associated with exposure to exogenous neurotoxic substances, the EU Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM) organized a workshop (March 2013, Ispra, Italy) to identify potential AOPs relevant to neurotoxic and developmental neurotoxic outcomes. Although the AOPs outlined during the workshop are not fully described, they could serve as a basis for further, more detailed AOP development and evaluation that could be useful to support human health risk assessment in a variety of ways.Peer Reviewe

Advanced Good Cell Culture Practice for human primary, stem cell-derived and organoid models as well as microphysiological systems

A major reason for the current reproducibility crisis in the life sciences is the poor implementation of quality control measures and reporting standards. Improvement is needed, especially regarding increasingly complex in vitro methods. Good Cell Culture Practice (GCCP) was an effort from 1996 to 2005 to develop such minimum quality standards also applicable in academia. This paper summarizes recent key developments in in vitro cell culture and addresses the issues resulting for GCCP, e.g. the development of induced pluripotent stem cells (iPSCs) and gene-edited cells. It further deals with human stem-cell-derived models and bioengineering of organo-typic cell cultures, including organoids, organ-on-chip and human-on-chip approaches. Commercial vendors and cell banks have made human primary cells more widely available over the last decade, increasing their use, but also requiring specific guidance as to GCCP. The characterization of cell culture systems including high-content imaging and high-throughput measurement technologies increasingly combined with more complex cell and tissue cultures represent a further challenge for GCCP. The increasing use of gene editing techniques to generate and modify in vitro culture models also requires discussion of its impact on GCCP. International (often varying) legislations and market forces originating from the commercialization of cell and tissue products and technologies are further impacting on the need for the use of GCCP. This report summarizes the recommendations of the second of two workshops, held in Germany in December 2015, aiming map the challenge and organize the process or developing a revised GCCP 2.0.publishe

Recommendation on test readiness criteria for new approach methods in toxicology : Exemplified for developmental neurotoxicity

Multiple non-animal-based test methods have never been formally validated. In order to use such new approach methods (NAMs) in a regulatory context, criteria to define their readiness are necessary. The field of developmental neurotoxicity (DNT) testing is used to exemplify the application of readiness criteria. The costs and number of untested chemicals are overwhelming for in vivo DNT testing. Thus, there is a need for inexpensive, high-throughput NAMs, to obtain initial information on potential hazards, and to allow prioritization for further testing. A background on the regulatory and scientific status of DNT testing is provided showing different types of test readiness levels, depending on the intended use of data from NAMs. Readiness criteria, compiled during a stakeholder workshop, uniting scientists from academia, industry and regulatory authorities are presented. An important step beyond the listing of criteria, was the suggestion for a preliminary scoring scheme. On this basis a (semi)-quantitative analysis process was assembled on test readiness of 17 NAMs with respect to various uses (e.g. prioritization/screening, risk assessment). The scoring results suggest that several assays are currently at high readiness levels. Therefore, suggestions are made on how DNT NAMs may be assembled into an integrated approach to testing and assessment (IATA). In parallel, the testing state in these assays was compiled for more than 1000 compounds. Finally, a vision is presented on how further NAM development may be guided by knowledge of signaling pathways necessary for brain development, DNT pathophysiology, and relevant adverse outcome pathways (AOP).publishe