Toxicol. Sci. [JOURNAL]
Sun
200 papers
Statistical analysis of multi-endpoint phenotypic screening increases sensitivity of planarian neurotoxicity testing.
Ireland D, Word LJ, Collins ES
Toxicol Sci · 2025 Nov · PMID 40839344 · Full text
There is an urgent need for high-throughput screening (HTS) models to replace, refine, and/or reduce ("3Rs") vertebrate toxicity testing. Replacing in vivo animal studies is challenging for neurotoxicity and developmenta...
There is an urgent need for high-throughput screening (HTS) models to replace, refine, and/or reduce ("3Rs") vertebrate toxicity testing. Replacing in vivo animal studies is challenging for neurotoxicity and developmental neurotoxicity (DNT), where the functional relevancy of adverse outcomes needs to be assessed on the whole organism. We previously screened the NTP 87-compound library (NTP87), consisting of known and suspected developmental neurotoxicants, and showed that planarian HTS can identify known (developmental) neurotoxicants. Because analysis methods can impact screening results, and our original analysis used the lowest-observed-effect-level (LOEL) only, we hypothesized that the use of state-of-the-art statistical analysis would increase the sensitivity of planarian HTS to identify neurotoxicity and DNT. Using the original NTP87 planarian data, we quantified 8 additional behavioral endpoints for a total of 26 readouts on days 7 and 12 of exposure, evaluated at 5 log-scale concentrations (10 nM-100 µM). Benchmark concentration (BMC) modeling replaced LOEL analysis. We also calculated a concentration-independent multi-readout summary measure using weighted Aggregate Entropy, providing insight into systems-level toxicity. Finally, we compared the planarian BMC data to in vitro and developing zebrafish data from independent screens of the NTP87 library that were analyzed using the same BMC pipeline. Planarian and developing zebrafish screens showed similar sensitivity. Regenerating planarian hits helped correctly identify known neurotoxicants of the NTP87 library. Hierarchical clustering showed that organismal, neuron outgrowth, and neuron firing models were the main contributors to the NTP87 DNT battery's information content, emphasizing their relevance for DNT testing.
Development of a physiologically based pharmacokinetic model of N,N-dimethyltryptamine, harmine, and their interactions from ayahuasca in rats and humans.
Wittayakarn N, Tan YM, Choomalaiwong P … +4 more , Chen S, Hoer D, Thaoboonruang N, Lohitnavy M
Toxicol Sci · 2025 Nov · PMID 40839168 · Publisher ↗
Ayahuasca is a traditional Amazonian brew composed of Psychotria viridis, containing N,N-dimethyltryptamine (DMT), and Banisteriopsis caapi, which includes harmala alkaloids such as harmine. Ayahuasca can produce potent...
Ayahuasca is a traditional Amazonian brew composed of Psychotria viridis, containing N,N-dimethyltryptamine (DMT), and Banisteriopsis caapi, which includes harmala alkaloids such as harmine. Ayahuasca can produce potent psychoactive effects primarily due to DMT, whose metabolism is inhibited by harmine via monoamine oxidase-A enzymes. This inhibition increases DMT's systemic bioavailability, thereby allowing more DMT to reach the brain and intensify its psychedelic effects. Beyond its traditional psychoactive uses, ayahuasca has shown potential therapeutic benefits for mental health conditions such as depression, anxiety, and substance use disorders. To support better design of dosing regimens in both preclinical and clinical settings, we developed linked physiologically based pharmacokinetic (PBPK) models for DMT and harmine in rats and humans. The models account for multiple routes of administration (intraperitoneal, oral, intravenous, and buccal) and integrate harmine's inhibition of DMT metabolism in the liver and lungs. Key absorption and metabolism parameters were optimized using published time-concentration data. The models reasonably predicted plasma concentrations of DMT and harmine across various dosing conditions. Simulation results offer insights into how the route of administration and co-administration with harmine influence exposure. The model also enables exploration of the dose metric driving the therapeutic effects, suggesting that plasma concentration above a threshold may be more relevant than peak levels. Overall, this PBPK model offers a mechanistic framework for guiding preclinical and clinical studies, supporting safer and more effective therapeutic use of ayahuasca and potentially other psychedelic compounds.
Advanced cardiac organoid model for studying doxorubicin-induced cardiotoxicity.
Wu X, Williams S, Robidoux J … +2 more , Sriramula S, Abdel-Rahman A
Toxicol Sci · 2025 Nov · PMID 40796330 · Full text
Cardiac organoids provide an in vitro platform for studying heart disease mechanisms and drug responses. However, a major limitation is the immaturity of cardiomyocytes, restricting their ability to mimic adult cardiac p...
Cardiac organoids provide an in vitro platform for studying heart disease mechanisms and drug responses. However, a major limitation is the immaturity of cardiomyocytes, restricting their ability to mimic adult cardiac physiology. Additionally, the inadequacy of commonly used extracellular matrices (ECMs), which fail to replicate the biochemical and mechanical properties of natural heart tissue, poses significant challenges. Consequently, structural integrity in cardiac organoids is impaired. Moreover, scalability remains an obstacle, as conventional ECM substitutes hinder mass production of organoids for high-throughput toxicology screening. To overcome these challenges, we developed an advanced model promoting fibroblast-driven ECM self-secretion, enabling physiologically relevant tissue architecture and function. Using the ECM-free, mature cardiomyocyte-integrated organoid model, we investigated the cardiotoxicity of doxorubicin, a widely used chemotherapeutic agent known to impair cardiac function. Cardiomyocytes derived from induced pluripotent stem cells were characterized for maturity by immunostaining for cardiac troponin T and myosin regulatory light chain 2 alongside gene expression analysis. Organoids treated with doxorubicin showed reduced size and increased collagen deposition. These structural changes correlated with functional impairments, including decreased beating rate and disrupted synchronous beating. In 2D culture, exposure to doxorubicin induced fibroblast activation, promoted early molecular signatures of endothelial-to-mesenchymal transition in endothelial cells, and triggered cytotoxic effects in cardiomyocytes. This study highlights the importance of ECM remodeling in advancing cardiac organoid models and demonstrates its potential for more accurate cardiotoxicity assessment. Addressing these limitations enhances the physiological relevance of cardiac organoid systems for drug safety assessment and cardiac disease modeling.
Circular RNA hsa_circ_0099188 regulates inducible nitric oxide synthase and chemokine transcription in macrophages by targeting the hsa-miR-381-3p/PPP3CA and hsa-miR-381-3p/KLF4 pathways in response to 4,4'-methylene diphenyl diisocyanate-glutathione conjugate exposure.
Lin CC, Law BF, Hettick JM
Toxicol Sci · 2025 Nov · PMID 40796177 · Full text
Workplace exposure to 4,4'-methylene diphenyl diisocyanate (MDI), the most used monomeric diisocyanate, can lead to the development of occupational asthma (OA). However, the molecular mechanisms by which MDI induces OA r...
Workplace exposure to 4,4'-methylene diphenyl diisocyanate (MDI), the most used monomeric diisocyanate, can lead to the development of occupational asthma (OA). However, the molecular mechanisms by which MDI induces OA remain poorly understood. Previous studies have shown that exposure to MDI or MDI-glutathione (GSH) conjugate reduces the levels of endogenous human (hsa)/murine (mmu)-microRNA (miR)-206/381-3p, triggering the activation of calcineurin/nuclear factor of activated T-cells/inducible nitric oxide synthase (NOS2) regulatory axis and Krüppel-like factor 4 (KLF4)/chemokine pathways in macrophages. Circular RNAs (circRNAs) play important roles on miR and miR-mediated functions in the cells. CircRNA hsa_circ_0008726 is induced by MDI-GSH to downregulate endogenous hsa-miR-206-3p in macrophages; however, the MDI-GSH mediated circRNA response to downregulate hsa-miR-381-3p is currently unknown. The expression of previously identified candidate circRNAs that bind hsa-miR-381-3p were analyzed in differentiated/enhanced THP-1 macrophages treated with MDI-GSH conjugates using RT-qPCR. MDI-GSH exposure induces endogenous hsa_circ_0099188 and its host gene thyrotropin-releasing hormone-degrading ectoenzyme (TRHDE); however, other candidate circRNAs were neither detected nor altered. RNA immunoprecipitation experiments confirmed the binding of hsa-miR-381-3p to hsa_circ_0099188. Further experiments demonstrate that modulating hsa_circ_0099188 expression through siRNAs or overexpression plasmids alter the levels of endogenous hsa-miR-381-3p, PPP3CA, and KLF4, as well as NOS2 and M2 macrophage-associated markers and chemokine transcripts. These findings suggest that MDI/MDI-GSH exposure leads to the downregulation of hsa-miR-381-3p by inducing the expression of hsa_circ_0099188/TRHDE, thereby enhancing the regulatory effects of hsa-miR-381-3p in macrophages.
Mediation analysis of the molecular phenotypes in a severe MASH-like liver injury mouse model.
Song Z, Tryndyak VP, Willett RA … +3 more , Pogribny IP, Rusyn I, Wright FA
Toxicol Sci · 2025 Nov · PMID 40795813 · Full text
Metabolic dysfunction-associated steatohepatitis (MASH), a severe form of fatty liver disease, is a leading cause of cirrhosis and lacks effective therapies. Understanding the molecular mediators of disease progression r...
Metabolic dysfunction-associated steatohepatitis (MASH), a severe form of fatty liver disease, is a leading cause of cirrhosis and lacks effective therapies. Understanding the molecular mediators of disease progression remains a critical gap. This study aimed to investigate the roles of molecular phenotypes as mediators of MASH disease features in a diet-induced mouse model. Data used for these analyses were from a previous study where male and female CC042 mice were fed either a control or high-fat, high-sucrose (HF/HS) diet for 20, 40, or 60 weeks. Associations and mediated relationships between molecular and metabolic phenotypes and histopathologic markers of liver injury, inflammation, and lipid accumulation were assessed using regression modeling and causal mediation analyses. We observed strong associations between the HF/HS diet and duration of treatment and liver pathology, with a limited effect of sex. Mediation analysis revealed that liver lipid phenotypes, particularly monounsaturated and polyunsaturated fatty acids, consistently mediated the effects of diet on liver disease scores. Tumor necrosis factor alpha and C-X-C motif chemokine ligand 10, despite being treatment-induced, showed modest evidence of mediation on MASH or specific liver disease outcomes. Serum insulin showed modest mediation of inflammation and osmium staining, while serum glucose and triglycerides were not significant mediators. These findings highlight evidence that liver lipid metabolism may act as a primary mediator of MASH progression in this mouse model. The study underscores the value of mediation analysis for improved characterization of metabolic pathways in disease pathogenesis and supports the use of serum lipids as accessible biomarkers for clinical risk stratification and therapeutic targeting in MASH.
Why rat oral cavity tumors should not be the basis of quantitative cancer risk assessment for oral exposure to hexavalent chromium.
Proctor D, Jiang X, Reichert H … +1 more , Thompson C
Toxicol Sci · 2025 Nov · PMID 40795394 · Full text
Several regulatory agencies have developed threshold-based drinking water guidelines for hexavalent chromium [Cr(VI)] protective of nonneoplastic and neoplastic lesions in rodents using small intestine tumor data in mice...
Several regulatory agencies have developed threshold-based drinking water guidelines for hexavalent chromium [Cr(VI)] protective of nonneoplastic and neoplastic lesions in rodents using small intestine tumor data in mice. However, in 2024, the US Environmental Protection Agency Integrated Risk Information System (IRIS) set an oral cancer slope factor based on oral cavity tumors in rats following chronic exposure to up to 180 ppm Cr(VI) in drinking water. Herein, we review previously published in vivo mechanistic data in rat oral cavity tissue indicating the absence of mutation responses in oral cavity tissue of transgenic Big Blue® rats and the absence of transcriptomic responses in F344 rats indicative of toxicological or homeostatic changes in the oral cavity following exposures up to 180 ppm Cr(VI). In addition, we extended an IRIS meta-analysis of gastrointestinal cancers by including oral cavity cancers, using the same epidemiological studies and approach as IRIS. We observed a significantly decreased meta-relative risk (meta-relative risk: 0.81, 95% CI: 0.69 to 0.95 and 0.74, 95% CI: 0.068 to 0.81 using random and fixed effect models). Given the lack of evidence for genotoxicity or even homeostatic responses to Cr(VI) in the rat oral cavity and the absence of oral cancer risk in humans, oral toxicity criteria for Cr(VI) should not be based on oral cavity tumors in rats. Many agencies have instead developed threshold-based toxicity criteria using nonneoplastic intestinal lesions observed in mice due to strong evidence for a cytotoxicity/regenerative proliferation mode of action for intestinal tumors, which were observed at lower drinking water concentrations than rat oral tumors.
Are New Approach Methodologies (NAMs) the Holy Grail of toxicology?
Jaeschke H, Ramachandran A
Toxicol Sci · 2025 Nov · PMID 40795217 · Full text
New Approach Methodologies (NAMs), including organoids, microphysiological systems, and computer modeling, are gaining increased popularity for toxicological testing and even mechanistic research. With the use of human c...
New Approach Methodologies (NAMs), including organoids, microphysiological systems, and computer modeling, are gaining increased popularity for toxicological testing and even mechanistic research. With the use of human cells, the primary objectives of NAMs are to develop more human-relevant test systems and to reduce, and ultimately eliminate, animal experiments. There are many advantages of using NAMs for biological research. For example, NAMs can be used to test the dose- and time-dependent toxicity of numerous chemicals and mixtures in a cost-effective way and reduce animal use. Although these are worthwhile goals when considering the big picture, the problems lie in the details. First, in vivo insight is needed to build and refine NAMs, including computer modeling. Second, primary human cells are difficult to obtain reliably and in sufficient quantities; substitutes such as immortalized cell lines or induced pluripotent stem cells have the advantage of being more robust and available in unlimited numbers, but their basal and stress-induced gene expression profiles are quite different compared with primary cells. Third, critical aspects such as metabolic competency, the presence of various cell types in an organ, spatial aspects, oxygen gradients, and the role of inflammatory cells are very difficult to replicate in vitro. Therefore, in vivo experiments are necessary to verify results obtained with NAMs. Importantly, the results of both NAMs and the in vivo animal experiments need to be translatable to human disease processes. The advantages and limitations of NAMs are being discussed using the challenges of investigating mechanisms of drug hepatotoxicity as an example.
Systematic review of potential developmental and reproductive toxicity of microplastics.
Fitch S, Rogers J, Marty S … +5 more , Norman J, Schneider S, Rushton E, Wikoff D, Ellis-Hutchings R
Toxicol Sci · 2025 Oct · PMID 40794567 · Full text
Plastic microparticles, a form of microparticles commonly referred to as microplastics (MP), have been the focus of increasing interest for understanding potential human and ecological impacts, including the development...
Plastic microparticles, a form of microparticles commonly referred to as microplastics (MP), have been the focus of increasing interest for understanding potential human and ecological impacts, including the development of health-based benchmark values. This systematic review critically evaluates 24 mammalian studies reporting reproductive and developmental outcomes, a disproportionately focused research area, with a particular focus on methodological rigor and risk of bias. Fit-for-purpose aspects of selection, performance, and attrition bias were integrated into the critical appraisal to better understand the potential bias studies may have across these domains. All studies received a tier III rating based on the National Toxicology Program's Office of Health Assessment and Translation framework, indicating a high risk of bias and insufficient reliability for risk assessment. Key issues identified across the body of evidence include poor exposure characterization, inadequate outcome assessment, lack of validated test guidelines, and failure to account for critical reproductive parameters such as estrous cycle monitoring and sperm analysis standards. Additionally, discrepancies in the particle characterization and homogeneity of the test material limit comparability and reproducibility across studies. This work highlights the current limitations in the body of evidence in terms of internal and construct validity, which preclude any conclusions on MP-related reproductive toxicity, and details a path forward for investigators to consider in future research.
A systems toxicology approach implicates post-transcriptional regulatory networks in reproductive defects from PFAS exposure.
Bline AP, Jiang H, Levenson M … +1 more , Allard P
Toxicol Sci · 2025 Nov · PMID 40737503 · Full text
Per- and polyfluoroalkyl substances (PFAS) are highly persistent in the environment and widespread in consumer products, environmental media, and biological samples. However, limited toxicology data exist for many of the...
Per- and polyfluoroalkyl substances (PFAS) are highly persistent in the environment and widespread in consumer products, environmental media, and biological samples. However, limited toxicology data exist for many of the over 15,000 chemicals belonging to the PFAS family. Data are particularly lacking for exposures during germ cell development, which can have consequences for later-life fecundity. Here, we leverage the tractability of the model organism Caenorhabditis elegans to compare a "legacy" PFAS, i.e. perfluorooctane sulfonic acid (PFOS), with a chlorinated ether analog, 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA). We consistently observed negative effects of both PFOS and 6:2 Cl-PFESA on germ cell numbers along with increases in germline apoptosis and defective meiotic progression. These cellular observations corresponded with increases in embryonic lethality in offspring from developmentally exposed adults. Messenger RNA and small RNA sequencing revealed a clear signature of perturbation of the non-coding RNA-mediated germline regulatory network consistent with observed ex vivo disruption of P granules, liquid-like assemblages of RNA, and protein. Remarkably, we identified a strong gene-environment interaction between PFOS and 6:2 Cl-PFESA with another liquid-like structure, the synaptonemal complex (SC); syp3(OK758) hypomorphic mutants exhibited near-complete embryonic lethality with PFAS exposure. Thus, while performed at relatively high concentrations to ensure robust effect detection, our mechanistic findings provide a foundation for understanding the reproductive toxicity of PFAS across exposure scenarios. Altogether, our data show that the impacts of PFAS on germ cell development and function are associated with perturbation of liquid-like condensates, suggesting that PFAS physicochemical properties may contribute to their pleiotropic effects on biological systems.
Synergistic toxicity in alcohol-associated liver disease and PFAS exposure.
Stem AD, Tieghi RS, Chatzi VL … +4 more , Kleinstreuer N, Valvi D, Thompson DC, Vasiliou V
Toxicol Sci · 2025 Nov · PMID 40737496 · Full text
Alcohol-associated liver disease (ALD) remains a leading contributor to global morbidity and mortality. Chronic ethanol intake drives hepatocellular damage through multiple mechanisms, such as acetaldehyde-induced cytoto...
Alcohol-associated liver disease (ALD) remains a leading contributor to global morbidity and mortality. Chronic ethanol intake drives hepatocellular damage through multiple mechanisms, such as acetaldehyde-induced cytotoxicity, dysregulated lipid metabolism, oxidative stress, and inflammation. Per- and polyfluoroalkyl substances (PFAS) have emerged as major environmental contaminants, characterized by their persistence, bioaccumulation, and capacity to disrupt hepatic function. PFAS share pathogenic pathways with ALD, including interference with mitochondrial function, oxidative stress induction, and steatosis promotion via altered lipid homeostasis. As exposure to PFAS becomes increasingly widespread and the burden of ALD continues to rise, understanding their potential synergistic impact on liver function is crucial. This review synthesizes current findings on the central mechanisms of ALD pathology, summarizes the hepatotoxic effects of PFAS, and explores their converging roles in exacerbating liver injury. Key pathways of interest include shared disruption of fatty acid oxidation, additive oxidative stress, and immunomodulation. The potential for concurrent exposure in high-risk populations (such as occupational groups with elevated PFAS exposure and higher-than-average alcohol use) warrants concern, particularly given that these people often face more limited healthcare access. By identifying mechanistic convergences, this review underscores the need for targeted studies that address how common co-exposures to PFAS and alcohol may intensify liver pathology, the value of a systems biology approach for future investigations, and the importance of implementing strategies to mitigate these synergistic hazards.
Characterizing variability and uncertainty for parameter subset selection in PBPK models.
Schacht CM, Kapraun DF, Meade AE … +3 more , Bernstein AS, Tran HT, Schlosser PM
Toxicol Sci · 2025 Oct · PMID 40737488 · Full text
Physiologically based pharmacokinetic (PBPK) models describe the absorption, distribution, metabolism, and excretion of chemicals. Probabilistic PBPK models can be used to produce distributional estimates of human equiva...
Physiologically based pharmacokinetic (PBPK) models describe the absorption, distribution, metabolism, and excretion of chemicals. Probabilistic PBPK models can be used to produce distributional estimates of human equivalent doses (HEDs), which are external measures of human exposure predicted to result in a target internal dose, generated with Monte Carlo sampling and reverse dosimetry calculations. Very low HED percentiles represent individuals that are more sensitive to possible adverse effects of chemical exposures and are therefore frequently used in risk evaluation. Details of the parameter distributions used in probabilistic PBPK models impact HED distributions, but obtaining precise distributional estimates for all the parameters would be challenging. Therefore, we sought to determine methods that can identify the extent of model parameter influence on extreme HED percentiles. We first analyzed published PBPK models for dichloromethane and chloroform (for inhalation and oral exposures given 3 internal target levels each) by identifying the overall relative importance of parameters using global sensitivity analysis (GSA) methods. Then, we used a novel yet computationally expensive method to analyze the stability and sensitivity of extreme HED percentiles to input parameter distributions. Applying the traditional GSA methods allowed us to identify subsets of parameters most influential for accurately determining 1st and 99th percentiles, but the specific parameters included in those subsets varied for different models and exposure scenarios. Our results demonstrate that better characterizing PBPK model uncertainty by using precise distributional details for influential parameters informed by GSA methods may improve confidence in estimates of extreme percentiles of HEDs.
High-content imaging and transcriptomic analyses of the effects of bisphenol S and alternative color developers on KGN granulosa cells.
Iskandarani L, Bayen S, Hales BF … +1 more , Robaire B
Toxicol Sci · 2025 Oct · PMID 40714807 · Full text
Concerns about the adverse effects of bisphenol A (BPA), a chemical used for the production of polycarbonate plastics, epoxy resins, and as a color developer in thermal papers, have led to an increase in the use of 4,4-s...
Concerns about the adverse effects of bisphenol A (BPA), a chemical used for the production of polycarbonate plastics, epoxy resins, and as a color developer in thermal papers, have led to an increase in the use of 4,4-sulfonyldiphenol (bisphenol S; BPS), bis(3-allyl-4-hydroxyphenyl) sulfone (TGSA), 4-hydroxyphenyl 4-isoprooxyphenylsulfone (D-8), [3-[(4-methylphenyl)sulfonylcarbamoylamino]phenyl] 4-methylbenzenesulfonate (Pergafast-201; PF-201), and 2,4-bis(phenylsulfonyl)phenol (DBSP) as alternative color developers. Data on these chemicals are scarce, and little is known about their potential toxicity. We determined the effects of BPS, TGSA, D-8, PF-201, and DBSP on the phenotype, function, and transcriptome of KGN human granulosa cells. Using high-content imaging, we observed that TGSA was the most cytotoxic compound tested, followed by D-8, DBSP, PF-201, and BPS. Although the effects of these compounds on lysosomes, mitochondria, and oxidative stress were minimal, TGSA, D-8, and PF-201 drastically increased the number and total area of lipid droplets compared with the control. RNA sequencing analyses revealed that TGSA and D-8 exposure differentially regulated 2,414 and 2,563 genes, respectively. PF-201 was the least transcriptionally active chemical, significantly affecting only 6 transcripts. The predominant effect of TGSA was the activation of pathways related to the extracellular matrix, whereas both TGSA and D-8 inhibited pathways involved in cell cycle regulation, DNA replication, and DNA repair. Such mechanisms may be underlying the cytotoxicity and lipid droplet accumulation observed in KGN cells. These data suggest that alternative color developers such as TGSA, D-8, and PF-201 act by different mechanisms and may not be responsible replacements for BPA and BPS in thermal papers.
Comparative review of human health reference values of the United States.
Woodall GM, Kobylewski-Saucier SE, Shaffer RM … +2 more , Luke AM, Carlson LM
Toxicol Sci · 2025 Sep · PMID 40714797 · Full text
Human health reference values (HHRVs) developed by US governmental agencies and professional organizations are derived for specific purposes related to their organizational or statutory mandates, and for individual chemi...
Human health reference values (HHRVs) developed by US governmental agencies and professional organizations are derived for specific purposes related to their organizational or statutory mandates, and for individual chemicals or substance groups (e.g. manganese compounds). Choosing an appropriate chemical-specific value should be based on the risk assessment need and the specific exposure context, along with a basic understanding of the various types and the intended purposes of each available HHRV. In this overview, HHRVs have been broadly organized into 3 main categories: values for the general public, occupational exposure limits, and emergency response values. The goal of this overview is to equip the reader with a greater understanding of HHRVs, how they are meant to be applied, and key aspects to consider in selecting the most appropriate value. These key aspects include target population (e.g. general public of all ages vs. working-age adults), duration and frequency of exposure, health effect severity, confidence in the data set, use of well-documented and contemporary derivation methods, transparency and documentation of the value derivation, and the thoroughness of the review process. Chemical- and exposure scenario-specific needs should determine which HHRV is most appropriate; however, a most appropriate HHRV may not be available for every chemical and situation. Therefore, we present both considerations and limitations to guide the selection of an alternate HHRV based on suitability for the assessment scenario from among the available chemical-specific values.
De-risking seizure liability: integrating adverse outcome pathways (AOPs), new approach methodologies (NAMs), and in silico approaches while highlighting knowledge gaps.
Behl M, Karmaus A, Rao M … +8 more , Lane T, Harris J, Sachs C, Borrel A, Oyetade O, Unnikrishnan A, Hamm J, Hogberg HT
Toxicol Sci · 2025 Oct · PMID 40711969 · Full text
Animal studies are commonly used in drug development and in chemical and environmental toxicology to predict human toxicity, but their reliability, particularly in the central nervous system (CNS), is limited. For exampl...
Animal studies are commonly used in drug development and in chemical and environmental toxicology to predict human toxicity, but their reliability, particularly in the central nervous system (CNS), is limited. For example, animal models often fail to predict drug-induced seizures, leading to unforeseen convulsions in clinical trials. Evaluating environmental compounds, such as pesticides, also poses challenges due to time and resource constraints, resulting in compounds remaining untested. To address these limitations, a government-industry collaboration identified 27 biological target families linked to seizure mechanisms by combining key events from adverse outcome pathways (AOPs) with drug discovery data. Over a hundred in vitro assay endpoints were identified, covering 26 of the target families, including neurotransmitter receptors, transporters, and voltage-gated calcium channels. A review of reference compounds identified 196 seizure-inducing and 34 seizure-negative chemicals, with 80% being tested in the in vitro assays. However, some target familes were more data-poor than others, highlighting significant data gaps. This proof-of-concept study demonstrates how mechanistic seizure liability can be assessed using an AOP framework and in vitro data. It underscores the need for expanded screening panels to include additional seizure-relevant targets. By integrating mechanistic insights into early drug development and environmental risk assessment, this approach enhances compound prioritization, complements animal studies, and optimizes resource use. Ultimately, this strategy refines CNS safety evaluation in drug development, improves public health protection to neurotoxicants, and bridges knowledge gaps.
Evaluating the role of alveolar macrophages in tolerance to ozone.
Smith GJ, Nalesnik M, Immormino RM … +5 more , Simon JM, Harkema JR, Mock JR, Moran TP, Kelada SNP
Toxicol Sci · 2025 Oct · PMID 40711967 · Full text
Acute exposure to ozone (O3) causes pulmonary inflammation and injury in humans and animal models. In rodents, acute O3-induced inflammation and injury can be mitigated by pre-exposure to relatively low concentrations of...
Acute exposure to ozone (O3) causes pulmonary inflammation and injury in humans and animal models. In rodents, acute O3-induced inflammation and injury can be mitigated by pre-exposure to relatively low concentrations of O3, a phenomenon referred to as tolerance. Although tolerance was first described long ago, the underlying mechanisms are not known. We hypothesized that alveolar macrophages (AMs) play a key role in tolerance to O3 based on prior studies with other exposures. To enable our studies, we first generated a mouse model in which female C57BL6/NJ mice were pre-exposed to filtered air or 0.8 ppm O3 for 4 days (4 h/day), then challenged with 2 ppm O3 (3 h) 2 days later, and phenotyped for airway inflammation and injury 6 or 24 h thereafter. As expected, pre-exposure to O3 resulted in significantly reduced airway inflammation and injury 24 h following O3 challenge. Tolerance was associated with regenerative hyperplasia in the terminal bronchioles and changes in the frequency of proliferating alveolar type 2 cells. O3 pre-exposure altered the expression of ∼1,500 genes in AMs, most notably downregulation of Toll-like receptor and proinflammatory cytokine signaling pathways, suggesting AMs had become hypo-responsive. Depletion of tolerized AMs prior to acute O3 challenge did not, however, alter inflammation and injury. Additionally, adoptive transfer of tolerized AM to naïve recipient mice failed to alter responses to acute O3 challenge. In total, our results argue against an important role for AMs in tolerance to ozone and suggest that other cell types are involved.
Chemosensory tobacco product toxicology part 1: sensory mechanisms.
Lin W, Hill T, Stroup AM … +9 more , Sarles SE, Ogura T, Augustine F, O'Sullivan S, Rahman I, Robinson R, Jabba SV, Nuss C, Hensel E
Toxicol Sci · 2025 Oct · PMID 40708233 · Full text
Chemosensory systems detect and discriminate a wide variety of molecules to monitor internal and external chemical environments. They initiate olfactory, gustatory, and chemesthetic sensations; influence human brain cogn...
Chemosensory systems detect and discriminate a wide variety of molecules to monitor internal and external chemical environments. They initiate olfactory, gustatory, and chemesthetic sensations; influence human brain cognition and emotion; and guide a wide variety of behaviors essential for survival, including protective reactions, such as avoidance of contaminated foods and potential toxicants. Electronic nicotine delivery systems (ENDS) aerosolize e-liquids for inhaled consumption that typically contain flavorants, propylene glycol, vegetable glycerin, and nicotine. E-liquid aerosols also contain toxicants, such as formaldehyde, acetaldehyde, acrolein, and heavy metals. Chemosensory evaluation of ENDS aerosol plays an essential role in the assessment of whether a product will attract new users of all ages, as well as determining their likely use patterns, perceptions of product harm, satisfaction, and product selection. Nicotine and individual flavorant constituents stimulate multiple sensory receptor systems in complex patterns, initiating distinctive sensory perceptions depending on the chemical properties and quantity in the aerosol. There are limited data on chemosensory evaluation of ENDS aerosols and their influence on ENDS use and protective biologic mechanisms. This two-part manuscript provides an overview of (i) the physiology of the olfactory, gustatory, and chemesthetic chemosensory systems, their detection mechanisms, and their role in protective defenses; and (ii) the in vitro, in vivo, and in silico computer-based methodology available to evaluate ENDS irritants and toxicants, their impact on chemosensory pathways, the current state of the science related to e-liquid and ENDS aerosols, and challenges for future studies and scientific innovation.
Chemosensory tobacco product toxicology part 2: toxicological testing, assays, and state of the science.
Lin W, Hill T, Stroup AM … +9 more , Sarles SE, Ogura T, Augustine F, O'Sullivan S, Rahman I, Robinson R, Jabba SV, Nuss C, Hensel E
Toxicol Sci · 2025 Oct · PMID 40705669 · Full text
The toxicologic impacts on the normative function of the chemosensory system and the loss of its contribution to organism protection and homeostasis remain an underrepresented area of interest in the published literature...
The toxicologic impacts on the normative function of the chemosensory system and the loss of its contribution to organism protection and homeostasis remain an underrepresented area of interest in the published literature. The impact of chemical constituents in electronic nicotine delivery system e-liquids or aerosols on the chemosensory system is even less known, as are the effects on product selection and use behavior-and this may be an overlooked impact on the public health. This review is a snapshot of the current state of the science and opportunities for improving and increasing the volume of publications in chemosensory toxicology on the potential impacts of tobacco products. The proposed solutions rely on the determination of the scientific community to take advantage of an unexplored field of opportunity. Active research engagement and use of an integrative, risk-driven planning framework to address harmonization and data gaps in neurosensory research programs would support harmonization, improve scientific visibility in the published literature, and recruit additional investigators to this research community.
Culture media influences primary human bronchial epithelial cell morphology, differentiation status, and transcriptional response to ozone exposure.
Lester SA, Abdelwahab SH, Randell SH … +1 more , Kelada SNP
Toxicol Sci · 2025 Sep · PMID 40700611 · Full text
Exposure to the ambient air pollutant ozone induces acute and chronic respiratory health effects in part by causing inflammation of the airways. Several aspects of the inflammatory response to ozone can be modeled in vit...
Exposure to the ambient air pollutant ozone induces acute and chronic respiratory health effects in part by causing inflammation of the airways. Several aspects of the inflammatory response to ozone can be modeled in vitro using primary human bronchial epithelial cells (HBECs) cultured at an air-liquid interface. We tested two commonly used HBEC culture media systems, one proprietary and one non-proprietary, to identify which system yielded the most in vivo-like pro-inflammatory response to acute ozone exposure as reflected by gene expression. Cells from 6 donors were grown in each culture system in parallel, followed by examination of epithelial morphology and cell type proportions prior to ozone exposure. Cultures grown in the proprietary system were notably thicker and contained more ciliated and secretory cells, as well as internal cyst-like structures. The transcriptomic response to acute ozone exposure (0.5 parts per million ozone × 2 h) was strongly affected by media type. HBECs grown in the proprietary system exhibited minimal changes after ozone, with only 7 differentially expressed genes (DEGs). In contrast, HBECs grown in the non-proprietary system exhibited a more dynamic response with 128 DEGs, including hallmark response genes indicative of inflammation (CXCL8) and oxidative stress (HMOX1). Gene set enrichment analysis using the 128 DEGs further corroborated upregulation of oxidative stress and inflammation pathways. In total, our results indicate that the choice of HBEC culture media should be carefully considered to best model the in vivo response to ozone.
Perfluorooctanesulfonic acid (PFOS) antagonizes gamma-aminobutyric acid (GABA) receptors in larval zebrafish and mammalian models.
Owen R, de Macedo G, Nerlich J … +9 more , Scharkin I, Bartmann K, Döbler J, Engelmann B, Rolle-Kampczyk UE, Leuthold D, Gutsfeld S, Schweiger N, Tal T
Toxicol Sci · 2025 Oct · PMID 40700607 · Full text
Per- and polyfluoroalkyl substances are a class of synthetic chemicals detected ubiquitously in the environment, humans, and wildlife. Perfluorooctanesulfonic acid (PFOS) is one prevalent chemical previously shown to cau...
Per- and polyfluoroalkyl substances are a class of synthetic chemicals detected ubiquitously in the environment, humans, and wildlife. Perfluorooctanesulfonic acid (PFOS) is one prevalent chemical previously shown to cause adverse effects on nervous system function across in vivo and in vitro models, including dark-phase hyperactivity in larval zebrafish. The objective of this study was to evaluate the role of gamma-aminobutyric acid receptors (GABARs), GABAAR and GABABR, as mediators of dark-phase hyperactivity in PFOS-exposed larval zebrafish. Zebrafish were acutely exposed to 7.87 to 120 μM PFOS, 0.68 to 12.4 μM picrotoxin (GABAAR antagonist), 0.77 to 14.05 μM propofol (GABAAR-positive allosteric modulator), 4.4 to 80 μM saclofen (GABABR antagonist), 0.43 to 7.87 μM CGP13501 (GABABR-positive allosteric modulator), or the solvent control 0.4% dimethyl sulfoxide 60 min before behavior assessment at 5 days post fertilization. Co-exposures to positive allosteric modulators and PFOS were performed. Acute exposure to PFOS caused transient dark-phase hyperactivity. Concentration-dependent dark-phase hypoactivity was observed following acute propofol or CGP13501 exposure, in contrast to the concentration-dependent hyperactivity caused by acute picrotoxin exposure. Saclofen exposure provoked a modest reduction in dark-phase motor activity at the highest concentration tested. PFOS-induced hyperactivity was rescued to baseline activity by co-exposure to propofol or CGP13501. To assess relevance across species, electrophysiological measurements were performed in cultured mouse cortical neurons and BrainSpheres derived from human-induced pluripotent stem cells. PFOS exposure reduced GABAAR-mediated currents in mouse neurons. GABAAR- and GABABR-dependent units in BrainSphere-derived neural networks exhibited increased spiking activity following PFOS exposure. This study demonstrates that PFOS antagonizes GABARs in zebrafish, mouse, and human experimental systems. Taken together, this study supports the concept that early life-stage zebrafish can be used to rapidly identify causative mechanisms, conserved across taxa, by which xenobiotic agents alter neuroactivity.
Preimplantational ethanol exposure causes disturbances in gene expression and abnormalities in cerebral cortex morphogenesis and behavior.
Sugiyama R, Tanizaki M, Komada M
Toxicol Sci · 2025 Oct · PMID 40700603 · Full text
Preimplantational ethanol exposure during the early stages of pregnancy is associated with significant developmental abnormalities in the cerebral cortex and behavioral changes. This study explores the impact of such exp...
Preimplantational ethanol exposure during the early stages of pregnancy is associated with significant developmental abnormalities in the cerebral cortex and behavioral changes. This study explores the impact of such exposure on neurogenesis, cortical morphogenesis, neuronal development, and behavioral outcomes. Ethanol exposure impairs the proliferation of radial glial and intermediate progenitor cells, disrupting neurogenesis in the dorsal telencephalon. Histological analysis reveals reduced neuronal distribution and decreased microglia numbers, highlighting neuroinflammation's role in these abnormalities. Gene expression studies show disrupted BDNF expression and upregulation of neurogenesis-related genes like Ngn2 and NeuroD, suggesting a potential imbalance in neuronal differentiation. Behavioral assessments in postnatal mice indicate significant impairments in locomotor and psychomotor activities and altered social proximity, though overall social interaction remains largely unchanged. Observations from open field tests demonstrate reduced spontaneous and psychomotor activity in alcohol-exposed mice. In multi-individual settings, these mice show decreased inter-individual distance, suggesting altered social proximity preferences. These findings underscore the long-term consequences of early prenatal ethanol exposure on brain development and behavior. The disruption in cortical morphogenesis, along with neuroinflammation and altered gene expression, is linked to neurodevelopmental deficits characteristic of fetal alcohol spectrum disorders. Further studies are necessary to better understand the mechanisms involved and mitigate long-term impacts.
About
- Frequency
- Sun
- Papers found
- 200
- RSS feed
- Subscribe