Toxicol. Sci. [JOURNAL]
Sun
200 papers
Role of hemopexin in protoporphyrin IX distribution and cholestatic liver injury.
Gu R, Qin FY, Sun Z … +5 more , Wang X, Chen E, Lu J, Wang J, Ma X
Toxicol Sci · 2026 Apr · PMID 41955309 · Full text
Deficiency of ferrochelatase (FECH) in erythropoietic protoporphyria (EPP) leads to accumulation of its substrate, protoporphyrin IX (PPIX), the final intermediate in the heme biosynthesis pathway. PPIX is produced prima...
Deficiency of ferrochelatase (FECH) in erythropoietic protoporphyria (EPP) leads to accumulation of its substrate, protoporphyrin IX (PPIX), the final intermediate in the heme biosynthesis pathway. PPIX is produced primarily in the bone marrow and subsequently delivered to the liver, where it can cause cholestatic liver injury and, in severe cases, liver failure. A key unresolved question is how circulating PPIX is transported to the liver to initiate hepatic damage. Given the structural similarity between PPIX and heme, we investigated whether the heme carrier hemopexin (HPX) mediates this process. Using an EPP mouse model carrying a Fech mutation (Fech-mut), we generated mice additionally lacking Hpx (Fech-mut/Hpx-null). As expected, Fech-mut mice exhibited markedly elevated PPIX levels in both the circulation and liver. However, Hpx deficiency did not alter PPIX distribution in Fech-mut/Hpx-null mice, indicating that HPX is not required for the delivery of circulating PPIX to the liver. Similarly, Hpx deficiency did not modify the severity of PPIX-induced cholestatic liver injury. Computational modeling further revealed that PPIX-HPX binding is energetically unfavorable, making HPX-mediated uptake unlikely. In summary, HPX does not contribute to hepatic PPIX uptake or influence cholestatic liver injury in EPP. These findings redirect attention to alternative hepatic uptake mechanisms and underscore the need to define the pathways that modulate PPIX delivery to the liver and shape susceptibility to EPP-associated liver injury.
An adverse outcome pathway-aligned ex vivo mouse testicular organ culture platform for mechanistic integration of multi-level endpoints with recovery assessment.
Nakagiri H, Kodama K, Terasaka S … +5 more , Kashima M, Ikeda N, Nukada Y, Fujii K, Nagao Y
Toxicol Sci · 2026 Apr · PMID 41903202 · Full text
Mechanistic understanding is important for improving the safety assessment of male reproductive toxicity; however, current evaluations still rely primarily on in vivo studies. Therefore, the development of new approach m...
Mechanistic understanding is important for improving the safety assessment of male reproductive toxicity; however, current evaluations still rely primarily on in vivo studies. Therefore, the development of new approach methodologies (NAMs) requires test systems capable of capturing key events organized within adverse outcome pathways (AOPs). The PDMS ceiling (PC) method is a testicular organ culture technique previously used to detect testicular toxicity. However, its applicability as an AOP-aligned platform for multi-level mechanistic assessment, including recovery evaluation, has not been fully examined. Here, we evaluated the utility of the PC-based organ culture system for AOP-aligned assessment of testicular toxicity. Methoxyacetic acid (MAA), a testicular toxicant with established AOPs, was used as a reference compound. Molecular, cellular, and histological endpoints were assessed under identical conditions, and a membrane-supported PC (msPC) configuration was introduced to enable controlled recovery assessment. Testes from Acro3-EGFP transgenic mice, in which EGFP expression driven by the acrosin promoter accumulates in developing acrosomes, were cultured and exposed to MAA. GFP fluorescence indicating spermatogenic progression decreased in a concentration-dependent manner. Histological and immunohistochemical analyses demonstrated selective loss of pachytene spermatocytes with apoptosis, whereas transcriptomic profiling suggested disruption of cell cycle- and meiosis-related pathways consistent with established AOP-defined key events. Recovery of GFP fluorescence and tissue morphology occurred earlier in the msPC system than in the conventional PC method. These findings support the PC-based organ culture system as an AOP-aligned platform within NAMs for evaluating testicular toxicity and recovery.
Quantitative estimates of inter-individual variability for new approach methodologies-based systemic safety toolbox using a population-based human in vitro model.
Alshammari I, Ford LC, Tsai HD … +11 more , Lin HC, Negi CK, Dickey AN, Wright FA, Middleton AM, Baltazar MT, Reynolds J, Cable S, Punt A, Chiu WA, Rusyn I
Toxicol Sci · 2026 Apr · PMID 41883125 · Full text
Next-generation risk assessment (NGRA) frameworks use new approach methodologies (NAMs) to support regulatory decisions without animal testing. Although NAM-based approaches are well established for hazard and dose-respo...
Next-generation risk assessment (NGRA) frameworks use new approach methodologies (NAMs) to support regulatory decisions without animal testing. Although NAM-based approaches are well established for hazard and dose-response assessment, inter-individual variability is still typically addressed using default uncertainty factors for inter-individual variability. This study evaluated an NAM-based strategy to quantify chemical-specific variability using a human cell model. We hypothesized that integrating chemical-specific variability data into NGRA would yield more protective risk estimates. Using 131 human lymphoblastoid cell lines (LCLs) from four European and African subpopulations, we assessed differences in cytotoxic responses to 53 substances, including industrial chemicals, pharmaceuticals, pesticides, and consumer-use compounds. Concentration-response testing (0.3 nM to 300 μM) data were analyzed using Bayesian modeling to calculate points of departure per cell line. Of the substances tested, 18 exhibited cytotoxic effects, enabling the derivation of chemical-specific variability factors. These factors were designated as toxicodynamic variability factors at the 5th percentile (TDVF05) because of the limited metabolic capacity of lymphoblast cell lines. The median TDVF05 was 3.8 (range 1 to 46), largely consistent with default assumptions. A genome-wide association study (GWAS) identified genomic loci, primarily containing transporter and metabolism genes, associated with variability in cytotoxicity, suggesting mechanistic bases for inter-individual differences. Overall, this study shows that human LCLs are a practical high-throughput in vitro model for quantifying inter-individual variability, strengthening confidence in NGRA risk predictions and supporting hypothesis generation on chemical-specific genetic and mechanistic drivers of human variability. However, cell-based systems have limited coverage of adverse effects and require careful alignment with in vivo dosimetry.
In vitro and preclinical assessment of drug interactions between fluoroquinolones and a nonsteroidal antiinflammatory drug predicting risk of seizure.
Seki Y, Mihara I, Okawa T … +16 more , Ojima A, Aoyama K, Mikamoto M, Morimitsu Y, Kamakura T, Goto Y, Odawara A, Oshiro Y, Taniguchi T, Shiotani M, Yoshinaga T, Asakura S, Ishibashi Y, Matsuda N, Suzuki I, Miyamoto N
Toxicol Sci · 2026 May · PMID 41883118 · Publisher ↗
Seizures are a common reason for drugs to fail during development, but they are difficult to predict preclinically. Enoxacin, a fluoroquinolone, rarely causes convulsions as a monotherapy, but convulsions have been seen...
Seizures are a common reason for drugs to fail during development, but they are difficult to predict preclinically. Enoxacin, a fluoroquinolone, rarely causes convulsions as a monotherapy, but convulsions have been seen after combination therapy with fenbufen, a nonsteroidal antiinflammatory drug. The interaction between the drugs is thought to result from inhibition of GABAA receptors, which are not their primary targets. Here, we show that, among 15 marketed fluoroquinolones and 1 active metabolite, 6, including enoxacin, inhibited γ-aminobutyric acid (GABA)-evoked depolarization in cells expressing human GABAA receptors when administered with felbinac, the active metabolite of fenbufen. Within these 6, except for a prodrug, possessed a piperazinyl group at the seventh position of the quinolone ring. We also administered enoxacin or norfloxacin plus felbinac to rats and determined the cerebrospinal fluid concentrations of each drug when convulsions occurred. As we previously reported, an increase in network burst frequency recorded from primary cultured rat cortical neurons on microelectrode arrays is a risk marker for seizures, so we tested whether this assay could predict seizures induced by drug interactions between fluoroquinolones and felbinac. When co-administered with felbinac, only those fluoroquinolones that inhibited GABA currents in patch-clamp tests increased network burst frequency. Principal component analysis using 17 microelectrode array parameters supported that the mechanism of action was due to GABA antagonism in rodent neurons. Thus, the microelectrode array assay predicted seizure risks from the combination of enoxacin and the active metabolite of fenbufen and identified other fluoroquinolones with seizure risk potential.
Ovarian hormone deficiency enhances wood smoke-induced immune dysfunction via transcriptomic and metabolic alterations.
Oh M, Yazzie S, Lim E … +5 more , Edeh O, McVeigh C, Bolt A, Gillette JM, Zychowski KE
Toxicol Sci · 2026 Mar · PMID 41879291 · Full text
The increasing frequency and severity of wildfires have heightened public exposure to smoke, highlighting the importance of identifying susceptibility factors, including ovarian hormone deficiency. Here, we used single-c...
The increasing frequency and severity of wildfires have heightened public exposure to smoke, highlighting the importance of identifying susceptibility factors, including ovarian hormone deficiency. Here, we used single-cell RNA sequencing to profile bone marrow immune cells from ovariectomized (OVX) mice exposed to either filtered air (FA) or wood smoke (WS), followed by functional validation in macrophages from both OVX and Sham-operated mice. Single-cell analyses focused on the OVX context; interactions between surgery and exposure were confirmed at the functional level in assays that included both Sham and OVX groups. In OVX mice, WS broadly suppressed transcriptional programs involved in antigen processing, leukocyte activation, antiviral defense, and bone remodeling. This was associated with altered immune cell composition, including increased memory CD8+ T cells and decreased granulocytes and interferon-responsive populations. Bone marrow-derived macrophages (BMDMs) from WS-exposed OVX mice displayed metabolic reprogramming, characterized by the reversal of OVX-induced suppression of oxidative phosphorylation and glycolytic activity, along with reduced expression of M2-associated genes, without concurrent induction of M1-associated genes. This immune-metabolic decoupling suggests that WS exposure under ovarian hormone deficiency may imprint a lasting program in the bone marrow macrophage axis. Together, these findings show that ovarian hormone deficiency increases vulnerability to WS-induced immune disruption in the bone marrow. WS triggers macrophage reprogramming only under ovarian hormone deficiency, leading to heightened metabolic activity alongside suppression of key immune pathways, identifying a novel mechanism of immunotoxicity. These findings emphasize the need to consider hormonal status in air pollution risk assessment.
Isolated and combined exposure to polystyrene nanoplastics and a phthalate metabolite mixture disrupts antral follicle growth and function of mice in vitro.
Souza PV, Santacruz-Márquez R, Laws MJ … +2 more , Flaws JA, Scarano WR
Toxicol Sci · 2026 Apr · PMID 41866295 · Publisher ↗
Polystyrene nanoplastics (PS-NPs) are small particles derived from plastic degradation that have been detected in several human tissues. Phthalates are ubiquitous plasticizers used to increase flexibility in polymers whi...
Polystyrene nanoplastics (PS-NPs) are small particles derived from plastic degradation that have been detected in several human tissues. Phthalates are ubiquitous plasticizers used to increase flexibility in polymers which act as endocrine disruptors, impacting hormonal homeostasis. Considering that both pollutants have been detected in human follicular fluid, there is increasing concern regarding their potential effects on female reproductive health. This study evaluated the isolated and combined effects of environmentally relevant doses of PS-NPs and a phthalate metabolite mixture (MM) on antral follicle growth, hormone production, and the expression of genes involved in apoptosis, oxidative stress, steroidogenesis, and hormone receptor signaling. Antral follicles from adult CD-1 mice were cultured with vehicle control (DMSO and water), metabolite mixture (0.01, 0.1, 1, and 10 μg/ml), or PSNPs (5, 25, 50, and 100 μg/ml) or MM + PS-NPs (5 µg/ml PS-NPs + 0.01 µg/ml MM; 100 μg/ml PS-NPs + 10 μg/ml MM). Follicle growth was monitored every 24 h for 96 h. PS-NPs and MM were internalized by follicles and they inhibited follicle growth alone and in co-exposure. Both pollutants altered the expression of apoptosis-related (Casp3, Casp8, Bcl2) and oxidative stress-related (Cat, Nrf2, Gpx1) genes without significantly affecting steroid hormone levels. Co-exposure also reduced Esr2 and Ar expression, demonstrating more pronounced effects under low-dose combined exposure. Altogether, these findings indicate that environmentally relevant exposure to PS-NPs and phthalate mixtures impairs antral follicle growth and disrupts molecular pathways essential for ovarian function, highlighting potential pathways and the importance of understanding combined exposures in reproductive toxicity.
Temporal variation in markers of immune signaling and wound repair in primary human airway epithelial cells following acute versus repeated woodsmoke condensate exposure.
Hickman E, Chou CK, Seifert C … +4 more , Chappel J, Kim YH, Corteselli E, Rager JE
Toxicol Sci · 2026 Apr · PMID 41863394 · Full text
Wildfire smoke (WFS) exposures are becoming more common, and firefighters and community members are often exposed to WFS for days to weeks. Controlled studies assessing the effects of repeated exposure to WFS and woodsmo...
Wildfire smoke (WFS) exposures are becoming more common, and firefighters and community members are often exposed to WFS for days to weeks. Controlled studies assessing the effects of repeated exposure to WFS and woodsmoke (WS; as a surrogate for WFS) or compared acute versus repeated exposure have evaluated a limited number of timepoints and endpoints using rodent models. Here, we leveraged differentiated primary human bronchial epithelial cells (HBECs) to test the hypothesis that different molecular responses occur upon acute versus repeat exposures to WS. HBECs (n = 4 donors) were exposed to 22 µg/cm2 red oak WS condensate for an acute, 4-h exposure, or repeat exposures of 4 h/d, 3 d/wk, across 2 wk. Membrane permeability, cell viability, and transcriptional responses were measured at the end of each exposure paradigm, and secreted proteins were measured throughout the repeat exposure. Acute exposure significantly increased expression of genes involved in fibrosis and immune response, whereas repeated exposure significantly decreased expression of genes involved in tissue repair and remodeling. Secreted protein responses were similar to transcriptomic responses and demonstrated temporal variation in response to exposure. This study supports the feasibility of using HBECs to evaluate acute and repeat WS exposures and indicates differential responses from these exposures with direct relevance to pulmonary disease processes, including those involved in fibrosis, asthma, and chronic obstructive pulmonary disease. These findings highlight the need for future studies to better understand molecular responses to repeated smoke exposures.
Retraction of: Vitrigel-Eye Irritancy Test Method Using HCE-T Cells.
Toxicol Sci · 2026 Mar · PMID 41860146 · Publisher ↗
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Expansion of preexisting cancer driver mutant clones is induced by the genotoxic carcinogen benzo[b]fluoranthene in MutaMouse lung.
Faske JB, Gong B, LeBlanc DP … +9 more , Funk J, Zhou G, Kehm S, White PA, Robison T, Zeller A, Yauk CL, Marchetti F, Parsons BL
Toxicol Sci · 2026 Mar · PMID 41859812 · Full text
Clonal expansion (CE) of cells carrying cancer driver mutations (CDMs) is being developed as a biomarker of cancer risk. CE in lung of MutaMouse males treated with 0, 6.25, 12.5, and 25 mg/kg/d benzo[b]fluoranthene (B[b]...
Clonal expansion (CE) of cells carrying cancer driver mutations (CDMs) is being developed as a biomarker of cancer risk. CE in lung of MutaMouse males treated with 0, 6.25, 12.5, and 25 mg/kg/d benzo[b]fluoranthene (B[b]F) by gavage for 90 and 180 d was assessed by CarcSeq. DNA regions encompassing mouse correlates of human hotspot CDMs were PCR amplified, attaching 18-base unique molecular identifiers (UMIs) during the PCR. Following library preparation and sequencing, UMI-defined read families were assembled to produce single-strand consensus sequences (SSCSs). Recovered mutants with mutant fractions (MFs) ≥10-4 were stratified based on their occurrence in lung-specific or nonlung driver sequences and CE was assessed on a per mouse basis as median absolute deviation in mutant fraction (MAD). A significant, dose-dependent increase in MAD was observed for lung-specific MFs after 180 d of B[b]F treatment, a duration that did not cause a significant increase in lung lesions. Dose- and treatment duration-related increases in MF were observed for Egfr, the mouse correlate of a known human lung tumor driver gene. MF and mutation counts were significantly decreased in response to longer treatment duration for some nonlung drivers, suggesting negative selection. Importantly, the normalized trinucleotide mutation spectrum derived from CDMs reflects amplification of preexisting spontaneous mutations, distinct from those induced by B[b]F mutagenesis. These results show CarcSeq detects CE of preexisting cancer driver gene mutants induced by the genotoxic carcinogen B[b]F and suggest a CE endpoint may be useful for evaluating cancer risk associated with tumor promoters or complete carcinogens.
Integrating exposomics and multi-omics with dysbiosis biomarkers for clinical and environmental connections implicated in neuropathology. Cause and cure cluses.
Heidari H, Vincent M, Lawrence DA
Toxicol Sci · 2026 Apr · PMID 41857807 · Publisher ↗
Multi-omic investigations into environmental effects on health and disease are aided by inclusion of microbial microbiomes with assessment of mirobes producing metabolites that differentially modulate host organ function...
Multi-omic investigations into environmental effects on health and disease are aided by inclusion of microbial microbiomes with assessment of mirobes producing metabolites that differentially modulate host organ functions. The gut microbiome is key because many environmental toxicants enter the body orally and may disrupt gut microbes that help digest food, as well as the microbiome-gut-brain axis, which produces regulatory metabolites with systemic effects. Environmental stressors may differentially alter brain development and function, even among identical twins, in that over time, there may be divergence due to epigenetic effects from the environment, including microbes within the microbiome. The diversity of microbiomes is presented as playing a key role in the influence of organs on each other, health, and the development of disorders. The gut microbes and their metabolites may cause mitochondria to produce less ATP and more reactive oxygen species (ROS). The metabolites produced by microbes during the digestion of foods can nourish or harm a person's cellular and molecular functions and vary depending on each person's exposome. The detrimental effects of environmental stressors are discussed, focusing on how altered levels of neuropeptides, neurotransmitters, and the inflammatory/anti-inflammatory balance affect health and disorders. During ATP production, dysfunctional mitochondria may produce more ROS, which can lead to inflammation and oxidative stress, causing cell damage and disrupting products needed for neuronal development, connections, and functions. The balance between inflammatory/anti-inflammatory biomarkers and metabolites and between oxidants/antioxidants is discussed in relation to some clinical connections; for example, the proportions of CD4 and CD8 T cells in HIV patients and the ROS-to-glutathione ratio in inflammatory bowel disease and septic patients. These imbalances are reviewed regarding brain development and functions leading to anxiety, depression, and dementia. The integration of multi-omics, dysbiosis, and mitochondrial dysfunction with a person's clinical evaluation is discussed to inform the formulation of prevention measures and therapeutic interventions regarding environmental effects on the microbiome-gut-brain axis and physical and mental health.
Using fish models to understand the role of aryl hydrocarbon receptor (AHR)-interacting protein (AIP) in controlling sensitivity and resistance to dioxin-like compounds in vivo.
Karchner SI, Aluru N, Franks DG … +12 more , Mandl CA, Goldstone JV, Burke T, Champlin D, La Du JK, Perone DM, Stinson S, Truong L, Clark BW, Nacci D, Tanguay RL, Hahn ME
Toxicol Sci · 2026 Mar · PMID 41840760 · Full text
Humans are exposed to chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) that cause toxicity through activation of the aryl hydroca...
Humans are exposed to chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) that cause toxicity through activation of the aryl hydrocarbon receptor (AHR). There is inter-individual variation in sensitivity to the effects of AHR ligands, but it is not fully explained by variation in the AHR. A clue to the genetic mechanisms underlying differential sensitivity to AHR agonists has emerged from studies of Atlantic killifish (Fundulus heteroclitus) populations with evolved tolerance to PCBs, TCDD, and PAHs. Genomic studies of these populations identified AHR-interacting protein (AIP/Ara9/XAP2) as the strongest candidate resistance gene. However, the precise role of AIP in the mechanism of resistance is unknown. To understand the role of AIP in the toxicity of dioxin-like compounds in vivo, we used CRISPR-Cas9 to generate AIP loss-of-function alleles in killifish and zebrafish (Danio rerio). Homozygous mutant killifish and zebrafish die during larval development-by 30 and 12 d postfertilization, respectively-whereas heterozygous mutants develop, survive, and reproduce normally. During embryonic and early larval stages, homozygous mutant zebrafish exhibit reduced sensitivity to embryotoxic effects of exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB126) and TCDD. Gene expression profiling of aip-deficient larvae revealed hundreds of differentially expressed genes. PCB126 induced similar sets of well-known AHR-regulated genes in mutant and wild-type larvae, although with reduced magnitude overall in AIP mutants. This study highlights the important role of AIP in fish larval development and demonstrates that AIP status can influence the response of vertebrate embryos to dioxin-like compounds in vivo.
Comparative investigation of the potential of glyphosate and glyphosate-based formulations to cause oxidative stress and DNA damage in human skin and liver cell systems.
Smith-Roe SL, DeVito MJ, Co C … +19 more , Ramaiahgari SC, Easterling M, Rice JR, Dunlap PE, Crizer DM, Zhou Z, Merrick BA, Xie G, Harris SF, Shockley KR, Tandon A, Oktay A, Mav D, Shah R, Borrel A, Gombar V, Masten SA, Paules RS, Ferguson SS
Toxicol Sci · 2026 Mar · PMID 41830163 · Full text
Glyphosate is an herbicide found worldwide in glyphosate-based formulations (GBFs). Although glyphosate appears to have a low toxicity profile for humans and mammals, conflicting reports exist regarding the risk for canc...
Glyphosate is an herbicide found worldwide in glyphosate-based formulations (GBFs). Although glyphosate appears to have a low toxicity profile for humans and mammals, conflicting reports exist regarding the risk for cancer in humans. US-EPA and European regulatory agencies have described glyphosate as unlikely to pose a carcinogenic hazard to humans. However, the International Agency for Research on Cancer (IARC) classified glyphosate as "probably carcinogenic to humans (Group 2A)," citing "mechanistic data provide strong evidence for genotoxicity and oxidative stress." Given these discrepancies, the Division of Translational Toxicology at NIEHS designed an experimental strategy to expand mechanistic evidence and address critical gaps within existing literature (e.g. mechanistic evaluations of glyphosate alongside GBFs, inclusion of context-defining positive controls). Cell morphology, viability, H2O2, and γH2AX formation were assayed in human keratinocytes (HaCaT), previously cited by IARC, and human hepatocytes (HepaRG) to derive benchmark concentrations and fold-change response metrics. Our findings revealed glyphosate alone was weakly and inconsistently bioactive for oxidative stress and DNA damage when compared with positive controls. In contrast, most of the 13 GBFs evaluated were more clearly bioactive with no apparent correlation to varied glyphosate concentrations. Hierarchical clustering of biological responses revealed some bioactive GBFs to cluster near well-characterized positive controls for oxidative stress, whereas 4 GBFs clustered more similarly to negative controls and glyphosate. Collectively, this study provides a robust dataset with context-defining results that advance our understanding of the hazard potential of GBFs while revealing that glyphosate is likely not a primary driver of oxidative stress from GBF exposures.
Alleviating effects of fat mass and obesity-associated protein on fluoride-induced neurotoxicity in rat brain, primary neurons, and SH-SY5Y cells.
Zeng XX, He WW, Liao W … +10 more , Xiao X, Tu X, Deng J, Qi XL, Dong YT, Hong W, He Y, Xiao Y, Wei N, Guan ZZ
Toxicol Sci · 2026 Apr · PMID 41830162 · Publisher ↗
Chronic fluorosis can cause injury to the central nervous system. Because fat mass and obesity-associated protein (FTO) connected with demethylation of N6-methyladenosine (m6A) plays a crucial role in maintaining brain f...
Chronic fluorosis can cause injury to the central nervous system. Because fat mass and obesity-associated protein (FTO) connected with demethylation of N6-methyladenosine (m6A) plays a crucial role in maintaining brain function, we examined whether FTO might help resist the neurotoxicity of fluoride. Sprague-Dawley rats with chronic fluorosis and cultured nerve cells exposed to fluoride with overexpression or knockdown of FTO were employed. The Morris water maze test was employed to assess learning and memory. Expressions of FTO, m6A, postsynaptic density protein 95 (PSD95) and α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) and its subunit GluR2 mRNA stability, apoptosis, and reactive oxygen species (ROS) were determined by Western blotting, RT-PCR, and biochemical methods, respectively. The results showed that the impaired learning and memory of rats with chronic fluorosis, the decreased FTO, PSD95 and AMPARs, the elevated m6A, and the disrupted synapse morphology as well as apoptosis in their brains were determined. Similar abnormal changes were further confirmed in primary neurons and SH-SY5Y cells exposed to fluoride, accompanied by a significant decline of GluR2 and high ROS. Notably, overexpression of FTO reduced m6A, enhanced GluR2, and attenuated neurotoxicity induced by fluoride, whereas knockdown had the opposite effects. FTO can alleviate the neurotoxicity induced by fluoride, in which the mechanism may be involved in its regulating m6A to enhance expression of GluR2.
Serine hydrolase targets of a sarin surrogate anticholinesterase and oxime-mediated reactivation in rat brain.
Price CY, Meek EC, Ross MK … +1 more , Chambers JE
Toxicol Sci · 2026 Mar · PMID 41818676 · Publisher ↗
Although acetylcholinesterase (AChE) is the primary inhibitory target for organophosphate (OP) insecticides and chemical warfare nerve agents, research supports the concept that the wide range of systems affected by OPs...
Although acetylcholinesterase (AChE) is the primary inhibitory target for organophosphate (OP) insecticides and chemical warfare nerve agents, research supports the concept that the wide range of systems affected by OPs are not solely dependent on the anticholinesterase activity of OPs but are attributable to the inhibition of other serine hydrolases. Oxime reactivators play an integral role in the treatment of acute OP exposure by returning function to OP-inhibited AChE. Our laboratory has synthesized and patented a platform of oxime reactivators (US Patent 9,227,937) that have provided central neuroprotection through returning function to OP-inhibited AChE in the brain and preservation of neuronal and glial structures from damage in a rat model; the current US-approved oxime, pralidoxime, does not provide central neuroprotection. Thus, returning function to other OP-inhibited serine hydrolases by these novel oximes could provide additional secondary neuroprotection. Rat brain proteins were studied using activity-based protein profiling (ABPP) for serine hydrolase targets of a highly relevant sarin surrogate, nitrophenyl isopropyl methylphosphonate (NIMP), alone or in combination with Oxime 20, our lead novel AChE reactivator. ABPP indicated that NIMP significantly inhibited 6 serine hydrolases, and of these were the well-known serine hydrolases fatty acid amide hydrolase and monoacylglycerol lipase, which are important in endocannabinoid signaling. Oxime 20 administration after NIMP treatment showed only limited remediation of the inhibition experienced by these targets. The impact of this study is the identification of secondary serine esterase targets that could be explored for esterase reactivating therapeutics for the treatment of OP poisoning.
Metabolic and circadian bioenergetic alterations following perfluorooctanoic acid exposure and high-fat diet in female C57BL/6 mice.
Ahmed A, Wittenborn M, Dewitt J … +1 more , Woodlief T
Toxicol Sci · 2026 Apr · PMID 41803643 · Publisher ↗
Exposure to per- and polyfluoroalkyl substances (PFAS) elicits changes in various metabolic responses but few studies have evaluated whole-body metabolic changes. This study compared whole-body bioenergetics in adult fem...
Exposure to per- and polyfluoroalkyl substances (PFAS) elicits changes in various metabolic responses but few studies have evaluated whole-body metabolic changes. This study compared whole-body bioenergetics in adult female C57BL/6 mice orally dosed with 0 or 7.5 mg/kg perfluorooctanoic acid (PFOA) or fed a 60% high fat diet (HFD) for 24 h or 15 d. After 24 h, HFD mice showed increased oxygen consumption (VO2) and reduced active-phase respiratory exchange ratio (RER), indicating early lipid utilization. After 15 d, PFOA-exposed mice exhibited decreased resting RER and suppressed active VO2, suggesting impaired circadian metabolic activation. In contrast, HFD mice maintained elevated VO2 across both resting and active cycles and showed reduced RER variation between phases, indicating metabolic inflexibility. PFOA exposure also increased relative liver weights and ACOX-1 activity. HFD resulted in an increase in body weight and increase in fat mass without hepatomegaly. These results indicate that both exposure paradigms disrupt whole-body metabolism and circadian bioenergetics. PFOA induced pronounced peroxisomal proliferation and suppressed resting-cycle energy expenditure without weight gain, whereas HFD drove obesogenic effects with impaired substrate switching. These findings provide mechanistic insight into how environmental and dietary stressors alter metabolic rhythms.
Integration of human microbiota (SIHUMIx) and zebrafish models reveals microbiome-mediated host responses to azoxystrobin.
Wray C, Castañeda-Monsalve V, Engelmann B … +8 more , Rolle-Kampczyk UE, Schweiger N, Gutsfeld S, Ghosh D, Kader S, Tyler CR, Jehmlich N, Tal T
Toxicol Sci · 2026 Apr · PMID 41795836 · Full text
The gut microbiome is essential for neurodevelopment via bidirectional gut-brain axis signaling, yet environmental chemicals can potentially disrupt this communication by altering community structure and xenobiotic metab...
The gut microbiome is essential for neurodevelopment via bidirectional gut-brain axis signaling, yet environmental chemicals can potentially disrupt this communication by altering community structure and xenobiotic metabolism. In this study, we investigated whether the fungicide azoxystrobin, a known metabolic disruptor, modulates microbiome composition and function to influence neurobehavior. We utilized a simplified human gut microbiota model (SIHUMIx) and a vertebrate host model (larval zebrafish) to elucidate microbiome-mediated mechanisms of xenobiotic neurotoxicity. SIHUMIx was exposed to azoxystrobin for 7 days at 10% of the acceptable daily intake, followed by recovery. Integrated metaproteomic and metabolomic analyses revealed functional reprogramming of the microbiota, characterized by upregulation of vitamin and cofactor biosynthesis, nutrient acquisition, and detoxification pathways, and decreases in carbohydrate fermentation and amino acid turnover, consistent with reduced short-chain fatty acid levels. Microbiome-depleted and SIHUMIx-inoculated larvae were exposed to azoxystrobin at 4 days post fertilization, and neurobehavioral outcomes were assessed after 24 h using the Visual and Acoustic Motor Response assay. Azoxystrobin exposure disrupted non-associative habituation learning independent of microbiome status but induced dark-phase hyperactivity only in colonized larvae, indicating a microbiome-dependent phenotype. Targeted metabolomics revealed lower serotonin levels in microbiome-depleted larvae relative to colonized controls and that azoxystrobin exposure reduced serotonin in colonized larvae toward depleted levels. These results suggest that microbiota-dependent serotonergic signaling may modulate host responses to azoxystrobin. This integrated ex vivo-in vivo approach supports the concept that the microbiome is a key determinant of neurotoxic responses and underscores the importance of incorporating microbiome-mediated effects into chemical risk assessment frameworks.
Multimodal preclinical assessment of glucocorticoid-induced disruption of bone remodeling in Sprague-Dawley rats.
Tuladhar A, Carter C, Vaughan E … +15 more , Voorbach MJ, Kumar P, Marinopoulos A, Acharya A, Stolarik D, Sande EJ, Brayman T, Parrish KE, Huang X, Finnema SJ, Christmann R, Van Vleet TR, Enright B, Guffroy M, Fossey S
Toxicol Sci · 2026 Mar · PMID 41783944 · Publisher ↗
Skeletal toxicity is a critical consideration during drug development arising from on-target mechanisms and off-target effects. Standard histopathology used in preclinical toxicity studies lacks sensitivity to detect sub...
Skeletal toxicity is a critical consideration during drug development arising from on-target mechanisms and off-target effects. Standard histopathology used in preclinical toxicity studies lacks sensitivity to detect subtle skeletal alterations. Early detection of bone changes is essential especially for compounds that may interfere with skeletal remodeling, growth, or maintenance. We characterized serum markers of bone formation and turnover (procollagen type I N-terminal propeptide and osteocalcin) and resorption (C-terminal telopeptide of type I collagen) across developmental age group (1 to 8 mo) in naïve Sprague-Dawley rats and evaluated marker responsiveness in a positive-control prednisolone model (2-mo-old rats dosed 14 or 28 d). Biomarkers were interpreted alongside histology, imaging by micro-computed tomography and dual-energy X-ray absorptiometry. Serum biomarkers of bone formation and resorption decreased with age, along with physiological growth plate thinning in naive rats. In prednisolone-treated rats, biomarkers decreased at 14 and 28 d of daily dosing; histology demonstrated reduced growth plate thickness, increased marrow adiposity, and imaging revealed alteration of trabecular microarchitecture and bone mineral density relative to controls. These data indicate that serum bone biomarkers are sensitive to both normal maturational change and pharmacologic suppression of remodeling, and these biomarker shifts correspond with skeletal toxicity, reflecting early structural deterioration induced by glucocorticoid exposure. We show that integrating serum biomarkers with histology and high-resolution imaging enhances early detection of skeletal toxicity in preclinical studies with compounds having known or expected bone effects based on their pharmacology and informs selection of serum sampling time frame and translational monitoring strategies using imaging.
Exposure of endothelial cells to doxorubicin inhibits extracellular matrix production by dermal fibroblasts in a paracrine manner.
Jiang Z, Sorrentino G, Lopes Natário Pinto Gomes M … +5 more , Swan-Taylor A, Simsek S, Roelofs JJTH, Niessen HWM, Krijnen PAJ
Toxicol Sci · 2026 Mar · PMID 41776828 · Full text
Doxorubicin (Dox) is a potent chemotherapeutic with known vascular toxicity and connective-tissue damage. Endothelial cells (EC) and fibroblasts crosstalk is essential for vascular homeostasis and extracellular matrix (E...
Doxorubicin (Dox) is a potent chemotherapeutic with known vascular toxicity and connective-tissue damage. Endothelial cells (EC) and fibroblasts crosstalk is essential for vascular homeostasis and extracellular matrix (ECM) remodeling. This study aimed to explore whether Dox induces endothelial-to-mesenchymal transition (EndMT) and the paracrine effects of Dox-exposed EC on fibroblasts activation, senescence, and ECM synthesis. Human umbilical vein endothelial cells (HUVECs) were treated with Dox, and conditioned medium (CM) from EC was applied to human dermal fibroblasts for short- and long-term culture. Dox induced EndMT in ECs. Fibroblasts exposed to CM from Dox-treated EC exhibited early activation with increased fibroblast activation protein (FAP) and α-smooth muscle actin (α-SMA) at day 3, followed by a progressive senescent phenotype marked by elevated p21 and reduced Lamin B1 at day 21. ECM formation was impaired, with reduced collagen and increased transcriptional expression of matrix-degrading enzymes (MMP1 and MMP9). Cytokines profiling of the CM revealed decreased interleukin-1β (IL-1β), C-C motif ligand 2 (CCL2), and C-X-C motif ligand 10 (CXCL10), and elevated interleukin-6 (IL-6) levels. These findings demonstrate that exposure of EC to Dox induced endothelial dysfunction and elicited pathological paracrine signaling, driving fibroblast activation, myofibroblast transition, senescence, and ECM disruption. This mechanism may underlie Dox-related skin aging and delayed wound healing, and emphasizes the importance of endothelial dysfunction in chemotherapy-associated connective tissue damage and impaired repair.
Safetyome and specialized panels for over 3,000 phenotypes: a systematic and translational approach using human genetics and pharmacology.
Liu X, Chen YW, Xu X … +2 more , Smith D, Fan F
Toxicol Sci · 2026 Mar · PMID 41712761 · Full text
Drug candidates are often evaluated for their activities against unexpected targets (off-targets), to either prospectively flag potential hazards or to provide mechanistic insights for a given phenotype. The in vitro to...
Drug candidates are often evaluated for their activities against unexpected targets (off-targets), to either prospectively flag potential hazards or to provide mechanistic insights for a given phenotype. The in vitro to in vivo translatability is critical when selecting which "phenotypically consequential" off-targets to screen. To this end, human genetics and indication-based pharmacology offer unraveled insights. Enhanced natural language processing tools were applied to harness the power of large data obtained from 7 genetics and 2 pharmacology databases. Mapping biological roles to organ systems, we curated targets implicated in 22 organ systems of safety concerns, resulting in a safetyome composed of over ∼11,000 proteins. This is a significant expansion from our previously proposed screen, whose scope included phenotypes affecting 5 organ systems. Prioritization of the large panel using expression pattern and gene conservation across species resulted in a core panel of 500 targets. Mapping biological roles obtained from the databases to specific terms allowed us to systematically generate over 3,000 phenotype-based (specialized) panels, which can be used as gene or protein sets for issue resolution. All three components: The full safetyome, the core panel of 500 targets, and the over 3,000+ specialized panels, were systematically and orthogonally tested using independent data source, i.e., gene expression data from the Comparative Toxicogenomics Database. All panels, together with a user-friendly App, are published to aid effective safety assessment and issue resolution with strong "translational" focus.
Acute exposure to diethylhexyl phthalate (DEHP) and diisononyl phthalate (DiNP) impacts pituitary hormones and inflammatory markers, suggesting altered reproductive aging in adult female mice.
Ojo Y, Weis K, Laws M … +5 more , Chiang C, Santacruz-Marquez R, Ntomb FM, Flaws J, Raetzman L
Toxicol Sci · 2026 Mar · PMID 41712757 · Publisher ↗
Phthalates are ubiquitous endocrine-disrupting chemicals whose exposure is associated with accelerated reproductive aging in humans. We focused on the pituitary gland, the source of the gonadotropins: Follicle-stimulatin...
Phthalates are ubiquitous endocrine-disrupting chemicals whose exposure is associated with accelerated reproductive aging in humans. We focused on the pituitary gland, the source of the gonadotropins: Follicle-stimulating hormone (FSH) and luteinizing hormone (LH). We hypothesized that the common phthalates di-(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DiNP) modulate inflammation in the pituitary and impact gonadotropin expression acutely and during aging. To test this, female CD-1 mice were orally dosed with corn oil or varying concentrations of DEHP and DiNP for 10 days. Pituitary tissues were collected immediately after dosing or 15 months post-dosing, processed, and analyzed by quantitative real-time PCR (qPCR) and immunohistochemistry. We found that acute phthalate exposure did not alter Fshb and Lhb mRNA expression compared with controls, but both DEHP and DiNP reduced FSH immunopositive cell number. Phthalate exposure also decreased Il1b, and increased Il18 and Tnf mRNA levels compared with controls, suggesting an inflammatory imbalance. At 15 months post-dosing, DiNP exposure increased Lhb and Il1b mRNA levels, but repressed Fshb and Nlrp3 mRNA levels compared with controls. Next, using dissociated cultures, we investigated the impact of phthalates and the proinflammatory stimulus lipopolysaccharide (LPS) on inflammation and gonadotropin gene expression directly at the pituitary. Both the DEHP metabolite MEHP and LPS decreased Fshb, but not Lhb mRNA relative to control. MEHP also repressed the induction of Il1b by LPS. Together, these findings suggest that acute exposure to phthalate alters mRNA expression of inflammatory markers and gonadotropins in the pituitary, which could alter the process of reproductive aging.
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