Project description:Parabens have been used for decades as preservatives in food, drugs and cosmetics. The majority however, were banned in 2009 and 2014 leaving only methyl-, ethyl-, propyl-, and butyl-derivates available for subsequent use. Methyl- and propylparaben have been extensively tested in vivo, with no resulting evidence for developmental and reproductive toxicity (DART). In contrast, ethylparaben has not yet been tested for DART in animal experiments, and it is currently debated if additional animal studies are warranted. In order to perform a comparison of the four currently-approved parabens, we used a previously established in vitro test based on human induced pluripotent stem cells (iPSC) that are exposed to test substances during their differentiation to neuroectodermal cells. EC50 values for cytotoxicity were 906 µM, 698 µM, 216 µM and 63 µM for methyl-, ethyl-, propyl- and butylparaben, respectively, demonstrating that cytotoxicity increases with increasing alkyl chain length. Genome-wide analysis demonstrated that FDR-adjusted significant gene expression changes occurred only at cytotoxic or close to cytotoxic concentrations, for example 1,720 differentially expressed genes (DEG) at 1,000 µM ethylparaben, 1 DEG at 316 µM, and no DEG at 100 µM or lower concentrations. The highest concentration of ethylparaben that did not induce any cytotoxicity nor DEG was 1670-fold above the highest published concentrations reported in biomonitoring studies (60 nM ethylparaben in cord blood). In conclusion, cytotoxicity and gene expression alterations of ethylparaben occurred at concentrations of approximately three orders of magnitude above human blood concentrations; moreover, the substance fitted well into a scenario where toxicity increases with the alkyl chain length, and gene expression changes only occur at cytotoxic or close to cytotoxic concentrations. Therefore, no evidence was obtained suggesting that in vivo DART with ethylparaben would lead to different results as the methyl- or propyl derivates.
Project description:The objective of this work was to use transcriptional profiling to assess the biological activity of structurally related chemicals to define their biological similarity and with that, substantiate the validity of a read-across approach usable in risk assessment. Two case studies are presented, one with 4 short alkyl chain parabens: methyl (MP), ethyl (EP), butyl (BP), and propyl paraben (PP), as well as their main metabolite, p-Hydroxybenzoic acid (pHBA) with the assumption that PP was the target chemical; and a second one with caffeine (CA) and its main metabolites theophylline (TP), theobromine (TB) and paraxanthine (PX), where caffeine was the target chemical. The comprehensive transcriptional response of MCF7, HepG2, A549 and ICell cardyomiocytes was evaluated (TempO-Seq) after exposure to vehicle-control, each paraben or pHBA, caffeine or its metabolites, at 3 non-cytotoxic concentrations, for 6h. Differentially expressed genes (FDR ≥ 0.05, and fold change ±1.2≥) were identified for each chemical, at each dose of exposure, and used to determine similarities between them. Each of the chemicals is able to elicit changes in the expression of a number of genes, as compared to controls, particularly at the highest dose tested. Importantly, the transcriptional profile elicited by each of the parabens shares a high degree of similarities across the category members. The highest number of genes commonly affected by the parabens was found between BP and PP. The transcriptional profile of the parabens is similar to the one elicited by some estrogen receptor agonist, among other actives. Pathway enrichment analysis (MSigDB v7.0) of the transcriptional profile for each paraben indicated a significant overlap in the up- and down-regulated pathways across the four parabens.The highest similarity in biological activity was found between BP and PP. This was indicative of their biological similarity, and thus the validity of the read across among the group, with BT being the closest structural and biological analogue for PP. In the caffeine case and its main metabolites, the transcriptional profile elicited of all four compounds had a high degree of similarity across the cell types, with CA and TP being the most active. The most robust response was obtained in the cardiomyocytes with the highest transcriptional profile similarity between CA and TP. The transcriptional profile of the methylxantines is similar to the one elicited by inhibitors of phosphatidylinositol 3-kinase as well as other actives. Pathway enrichment analysis (MSigDB v7.0) of the transcriptional profile for each compound indicated a significant overlap in the up- and down-regulated pathways across the four methylxanthines. The highest similarity in biological activity was found between CA and TP, supporting the conclusion that from the group of methylxantines evaluated TP is the most appropriate analogue to read-across for CA. Overall, our results support the approach of incorporating transcriptional profiling in well-designed in vitro tests to support biological similarity driven read-across procedures and strengthening the traditional structure-based approaches useful in risk assessment.
Project description:Autism Spectrum Disorder (ASD) presents a wide, and often varied, behavioral phenotype. Impulsivity and improper assessment of risks has been widely reported among individuals diagnosed with ASD. However, there is little knowledge of the molecular underpinnings of the impaired risk-assessment phenotype. In this study, we have identified impaired risk-assessment activity in multiple male ASD mouse models. By performing network-based analysis of striatal whole transcriptome data from each of these ASD models, we have identified a cluster of glutamate receptor–associated genes that correlate with the risk-assessment phenotype. Furthermore, pharmacological inhibition of striatal glutamatergic receptors was able to mimic the dysregulation in risk-assessment. Therefore, this study has identified a molecular mechanism that may underlie impulsivity and risk-assessment dysregulation in ASD.
Project description:This study examined how transcriptomics tools can be included in a Triad-based soil quality assessment to assess the toxicity of soils from river banks polluted by metals. To that end we measured chemical soil properties and used the standardized ISO guideline for ecotoxicological tests and a newly developed microarray for gene expression in the indicator soil arthropod, Folsomia candida. Microarray analysis revealed that the oxidative stress response pathway was significantly affected in all soils except one. The data indicate that changes in cell redox homeostasis are a significant signature of metal stress. Finally, 32 genes showed significant dose-dependent expression with metal concentrations. They are promising genetic markers providing an early indication of the need for higher tier testing in soil quality. One of the least polluted soils showed toxicity in the bioassay that could be removed by sterilization. The gene expression profile for this soil did not show a metal-related signature, confirming that another factor than metals (most likely of biological origin) caused the toxicity. This study demonstrates the feasibility and advantages of integrating transcriptomics into Triad-based soil quality assessment. Combining molecular and organismal life-history traitM-bM-^@M-^Ys stress responses helps identifying causes of adverse effect in bioassays. Further validation is needed for verifying the set of genes with dose-dependent expression patterns linked with toxic stress. We used a one-color microarray design where each sample was hybridized to a single array
Project description:Assessing and responding to threats is vital in everyday life. Unfortunately, many mental illnesses involve impaired risk assessment, affecting patients, families, and society. The brain processes behind these behaviors are not well understood. We developed a transgenic mouse model (DISC1-N) with a disrupted avoidance response in risky settings. Our study utilized single-nucleus RNA sequencing to uncover a previously undescribed group of glutamatergic neurons in the basolateral amygdala (BLA) marked by WFS1 expression, whose activity is modulated by adjacent astrocytes. These neurons in DISC1-N mice exhibited diminished firing ability and impaired communication with the astrocytes. Remarkably, optogenetic activation of these astrocytes reinstated neuronal excitability via D-serine acting on BLAWFS1 neurons’ NMDA receptors, leading to improved risk-assessment behavior in the DISC1-N mice. Our findings point to BLA astrocytes as a promising target for treating risk assessment dysfunctions in mental disorders.