Toxicological Sciences最新文献

Nephrotoxicity is a major concern in the safety assessment of chemicals and drugs. Computational modeling, particularly the use of quantitative adverse outcome pathways (qAOPs), offers a promising strategy to improve the translation from in vitro to in vivo, thereby facilitating reliable predictions of in vivo adverse outcomes and potentially reducing the need for animal testing. Platinum-based drugs are widely used in chemotherapy, yet their clinical application is frequently constrained by nephrotoxic effects. Here, we focus on the development of ordinary differential equation (ODE)-based qAOPs for platinum-induced nephrotoxicity by defining both an in vitro and an in vivo data-driven model. The in vitro model incorporates newly generated, time-course gene expression and propidium iodide (PI) staining data from RPTEC/TERT1 cells exposed to cisplatin. The in vivo model employs published rat data, including dose-response platinum kinetics as well as single-dose time-course platinum kinetics, gene expression, and histopathology data. Our quantitative approach shows that key processes in the AOP related to immune system activity are nonlinear. Specifically, clearance of necrotic kidney cells by immune system activity counters damage accumulation on a timescale of days, yet low-level inflammation still cumulatively affects kidney failure in the long run. Moreover, we perform quantitative in vitro to in vivo extrapolation (QIVIVE) to link the 2 models. With this approach, in vivo adverse outcome predictions can be made in the future not only for platinum-based compounds but also for the safety assessment of other chemicals and drugs, reducing the need for animal testing.

Traditional chemical risk assessment is often based on published mammalian in vivo toxicity data, which are used to identify a point-of-departure (PoD) to derive the minimal risk level (MRL) and similar health guidance values. However, time and resource requirements prohibit efficient multi-target-organ toxicity assessments for a large number of environmental chemical pollutants. In vitro high-throughput screening (HTS) assays and other new approach methodologies (NAMs) could address this problem by using reverse dosimetry to contextualize activity concentrations obtained from the in vitro assays to in vivo settings. In this study, we selected sample priority of diverse chemicals for which both curated high-throughput screening (cHTS) assay data and acute oral MRLs were available for neurotoxicity, hepatotoxicity, and developmental toxicity. We obtained in vitro activity concentrations for these chemicals and conducted in vitro to in vivo extrapolation (IVIVE) to estimate the daily equivalent administered dose (EAD) that would result in rat or human plasma concentrations equivalent to the in vitro activity concentrations. The range of EAD values across various cHTS assays was then compared to in vivo PoDs, MRLs and predicted human exposure levels. Although variations existed depending on toxicity endpoints evaluated, our results showed that PoDs for a majority of chemicals can be predicted using such data. Our results also demonstrated that a majority of MRL and EAD values fall well below predicted human exposure levels. In summary, our findings demonstrate the usefulness and limitations of using cHTS data and IVIVE approaches for the derivation of health guidance values.

Parental exposure to toxicants can affect progeny health. However, laboratory studies often employ exposures that result in loading of pollutants to gametes, or toxic effects to parents which could indirectly affect germ cell or gamete health. Here, we took advantage of the biology of Caenorhabditis elegans to carry out a study in which we minimized the potential for maternal loading of toxicants, and used an exposure paradigm that either did (high concentration) or did not (low concentration) significantly impact the health of the P0 generation. We hypothesized that parental exposure to mitochondrial toxicants during germ cell and gamete development, at levels not causing P0 toxicity, would result in altered mitochondria and organismal health in offspring. In the P0 generation, a high rotenone concentration altered growth, mitochondrial respiration, gene expression, induction of the mitochondrial unfolded protein response, and susceptibility to dopaminergic neurodegeneration induced by a chemical rechallenge later in life. However, we observed minor or no effects in P0 at a low concentration. In high-exposure F1 offspring, we observed altered embryo size, larval developmental stage distribution, spare respiratory capacity, heat shock protein expression, and dopaminergic neurodegeneration after a secondary rotenone challenge. The only effects observed in the F1 offspring of the low exposure were a 1.7% decrease in egg size (size later in development was normal), and moderate evidence of a slightly increased sensitivity to heat shock protein expression and dopaminergic neurodegeneration caused by a secondary later-in-life rotenone exposure. We recommend parental toxicity be carefully assessed to contextualize offspring outcomes.

Volatile organic compounds (VOCs) are increasingly implicated in systemic diseases, but their contribution to skin disorders such as atopic dermatitis (AD) remains unclear. This study assessed VOC concentrations in medical environments, their effects on AD development, and the efficacy of VOC removal using chemical filters. Total VOC levels were monitored in three types of veterinary hospitals. AD-like lesions were induced in female NC/Nga mice by repeated dermal application of tolylene diisocyanate or house dust mite ointment, with or without topical exposure to a VOC mixture (10 μg/mL). Clinical parameters, including dermatitis scores, transepidermal water loss, and skin thickness, were measured weekly, and immunological and histological analyses were performed. VOC monitoring revealed that one hospital exhibited concentrations exceeding 400 μg/m³. In the mouse model, direct VOC exposure significantly aggravated keratinocyte inflammation and worsened AD symptoms. Application of chemical filtering systems effectively reduced VOC levels in real clinical settings, and their use in the experimental model suppressed AD development. However, therapeutic application of VOC removal showed only limited effects on systemic immunological markers. These findings suggest that VOCs present in healthcare environments may contribute to the onset and progression of AD. Incorporating VOC-removing filters into air-conditioning systems could serve as a preventive strategy to improve the management of allergic skin diseases.

Firefighters are exposed to high levels of toxic chemicals when fighting fires, and previous studies have established these men and woman have a significantly elevated risk for various cancers. Improved risk management for firefighters requires identification of biomarkers indicative of physiological response. Micro-RNAs (miRNA) have emerged as a promising noninvasive prognostic and diagnostic biomarkers for various diseases. Here we isolated miRNA from the urine of a large dataset of firefighters, collected pre- and post-fire exposure as well as from healthy non-firefighter controls. miRNA was analyzed by microarray using the Affymetrix GeneCHIP miRNA 4.0 array. Analysis revealed 23 human miRNAs were significantly up-regulated and 25 significantly down-regulated in firefighters compared to control samples (analysis 1). Gene targets of these miRNAs were analyzed using the Online Database for Annotation, Visualization, and Integrated Discovery (DAVID) and found to cluster in several pathways and disease associations with smoking, cancer, and inflammatory diseases. Furthermore, we performed a longitudinal analysis of samples from firefighters that provided a sample prior to a fire exposure and immediately after a fire (analysis 2). This analysis found 20 miRNAs that were significantly up-regulated post fire exposure. Of these, 5 were also up-regulated in firefighters vs control samples (hsa-miR-1268b, hsa-miR-4433b-3p, hsa-miR-4253, hsa-miR-6824-5p, and hsa-miR-3188). Again, analysis of gene targets of these miRNAs found association of mostly the same pathways and disease processes found in analysis 1. These findings are consistent with epidemiological evidence for increased risks associated with firefighting and offer a proof of concept and framework for the use of miRNA in urine as biomarkers for health risk assessment associated with firefighting.

Exposure to agricultural chemicals is a risk factor for neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). Chlorpyrifos (CPF) is an organophosphate insecticide widely used in agricultural and occupational settings. Epidemiological studies have associated CPF exposure with developmental impairments and an increased risk of AD and PD. Experimental characterization of the impact of chronic, systemic CPF exposure is essential for understanding how organophosphates actually influence disease risk. Multiple studies have assessed the effects of gestational exposure to CPF in preclinical models. To model exposure faced by adults, we administered CPF-contaminated drinking water to mice from 6 to 22 months of age. This chronic exposure led to systemic effects, including reduced levels of the acute-phase protein haptoglobin (HTP) in both plasma and liver. Notably, the combination of aging and CPF exposure resulted in astrogliosis in the hippocampus and striatum, as well as neuronal loss in the striatum, primarily due to the loss of GAD65/67-immunoreactive interneurons. Having identified CPF-driven suppression of HPT in peripheral tissues, we examined HPT expression in brain tissues. We readily detected HPT expression in brain microglia. We then cultivated primary microglia and found that CPF exposure decreased HPT secretion in vitro. These findings indicate systemic and neurotoxic effects resulting from adult exposure to CPF-contaminated water.

Cupferron, widely used in industrial and analytical contexts, has been proposed as a potential nitric oxide (NO) donor; however, its effects on the male reproductive system remain unclear. We assessed toxicity in TM3 (Leydig) and TM4 (Sertoli) mouse cells. Cytotoxicity (6-0.0035 mg/mL) was measured by MTT/NRU; genotoxicity by comet assay; oxidative stress markers (MDA, 8-OHdG, GSH, SOD) and testosterone by ELISA; cell death and ROS by flow cytometry; and gene expression by RT-qPCR. MTT IC50 values were 0.131 mg/mL (TM3) and 0.219 mg/mL (TM4). At 0.125 mg/mL, comet assay revealed markedly increased DNA damage, ≥ 16-fold (p ≤ 0.05) in both TM3 and TM4 cells. In TM4, MDA and 8-OHdG rose ≥ 1.3-fold, while SOD activity increased in both TM3 (1.2-fold) and TM4 (1.5-fold) cells (p ≤ 0.05). Annexin V/PI analysis indicated increased necrosis without significant changes in apoptosis. Testosterone levels were unaffected at all doses. RT-qPCR showed upregulation of SOD1, HMOX1, GSTA1, GPX1 antioxidant genes in both TM3 (1.and TM4 (p ≤ 0.05). Network toxicology highlighted NOS1, NOS3, and PTGS2 as putative targets, supported by docking indicating high affinity and substrate-like poses, implicating modulation of oxidative/inflammatory pathways. ADMETLab 3.0 predicted genotoxic, hepatotoxic, and carcinogenic risks. Overall, Cupferron induces oxidative stress, DNA damage, necrosis, and antioxidant gene activation in Leydig and Sertoli cells, supporting potential male reproductive toxicity and the need for comprehensive in vivo and mechanistic in vitro studies.

Ethylbenzene is a high production volume chemical. Exposure occurs in the general population but there is potential for additional exposure in certain groups such as workers in petrochemical industries or individuals living near contaminated areas. This paper presents a systematic review of currently available evidence in animals focused on potential nervous system related effects of ethylbenzene exposure. A broad literature search was conducted. A total of 9,679 studies were screened for inclusion based on Population, Exposure, Comparator, and Outcome (PECO) criteria. Included studies were evaluated for potential concerns related to risk of bias and sensitivity and informative studies moved forward for data extraction and evidence synthesis. Twenty-one animal toxicology studies were identified that evaluated nervous system effects including auditory effects, neurotransmitters, neurobehavior, brain weight, and histopathology. Six studies rated medium or low confidence showed consistent concentration- and exposure duration-related effects on cochlear hair cells and hearing thresholds. The evidence for the other nervous system outcomes is inconclusive. Although some studies showed effects on neurotransmitters and neurobehavior, they were rated low confidence and findings were inconsistent. Relative brain weight changes were observed but the direction of the effect was inconsistent. No changes were observed in absolute brain weights which is considered the more reliable measure for evaluating effects on brain weight. No changes in brain histopathology were reported. Disclaimer: The views expressed in this paper are those of the authors and do not necessarily represent the views or policies of the U.S. EPA.

Background: Hepatocellular mitochondrial depolarization (mtDepo) after ethanol (EtOH) increases respiration to stimulate EtOH detoxification. mtDepo also triggers mitophagy, which may contribute to alcohol-associated liver disease. This study characterized sublobular respiration and distribution of mtDepo and mitophagy after acute EtOH.

Methods: C57BL/6J and GFP-LC3 transgenic mice were gavaged with 6 g/kg EtOH or vehicle and administered MitoTracker Red (MTR). Hepatocytes were zonally sorted by MTR fluorescence for assessment of oxygen consumption rates (OCRs). Cytochrome P4502E1 (CYP2E1) immunolabeling identified central halves of liver lobules.

Results: After vehicle, MTR localized to mitochondria throughout lobules, indicating polarization, with higher OCRs in periportal (PP) hepatocytes compared to pericentral (PC). After EtOH, MTR fluorescence became diffuse in CYP2E1-positive central halves of lobules, signifying mtDepo, whereas portal halves remained polarized. GFP-LC3 puncta marking mitophagy also increased predominantly in central halves. Surface hepatocytes accessible by multiphoton microscopy were CYP2E1-positive and developed mtDepo and GFP-LC3 puncta after EtOH. After hepatocyte isolation, mtDepo reversed shown by rhodamine 123 uptake. At 6 h post-EtOH, OCRs approximately doubled in both PP and PC hepatocytes, returning to baseline by 24 h, but PC displayed greater proportional increases.

Conclusions: Acute EtOH induces mtDepo and mitophagy predominantly in central halves of lobules, including within <50-μm of the liver surface. Although mtDepo reverses after isolation, elevated respiratory capacity persists. Due to central half mtDepo, PP and PC hepatocytes contribute about equally to the respiratory burst after EtOH.