Toxicological Sciences最新文献

Chronic kidney disease (CKD) affects ∼15% of U.S. adults and over 840 million people worldwide. Environmental contaminants, including pesticides and metals, are increasingly recognized as disease contributors, yet mechanisms and consequences of long-term, low-level mixture exposures remain poorly defined. Our prior work identified glyphosate and metals (cadmium, arsenic, lead, vanadium) in drinking water from agricultural regions with high CKD prevalence and showed that early-life co-exposures disrupt kidney development. Here, using adult zebrafish as a mechanistic model, we tested whether chronic, low-level exposure to glyphosate, metals, and their combination impairs kidney function and structure. We exposed zebrafish for 10 and 60 days to glyphosate (10 ppb), metals (2 ppb Cd, 4 ppb As, 5 ppb Pb, 15 V), or glyphosate + metals and evaluated low-molecular weight proteinuria, histopathology, metabolomics, mitochondrial function, mitochondrial copy number, and mitophagy in the kidney. Chronic exposure to glyphosate and metals produced distinct yet overlapping kidney toxicity signatures, including tubular injury, altered metabolism, and impaired mitochondrial function. Co-exposures generated the most severe effects, with mitochondrial beta oxidation, respiration, and mitophagy as sensitive targets. These findings demonstrate that glyphosate and metals at levels found in drinking water damage kidney function over time, with co-exposure worsening outcomes compared to individual chemicals. Our study identifies mitochondria-rich proximal tubules as critical targets of chronic glyphosate-metal exposure, providing mechanistic insight into how environmental contaminants contribute to CKD risk. This work advances understanding of disease etiology in environmental nephropathies and highlights environmental factors as important drivers of kidney health.

Thyroid hormones (THs) influence testis development, with early life hypothyroidism resulting in smaller testes. Developmental exposure to thyroperoxidase (TPO)-inhibiting drugs such as propylthiouracil (PTU) and methimazole (MMI) also impair testis development in rodents by reducing TH levels, leading to smaller testes in pups due to, for instance, disrupted Sertoli cell proliferation and maturation. Comparable effects are seen following exposure to the TPO-inhibiting pesticide amitrole, one of many environmental chemicals with TH-disrupting properties. Despite this phenotype, the molecular underpinnings of hypothyroid-induced testis effects are less clear, complicating mechanism-based chemical toxicity testing relying on alternative test methods and omics approaches. Here, we report on transcriptomics profiling of testes from hypothyroid rats induced by chemical exposures. Pregnant Sprague-Dawley rat dams were exposed by oral gavage to two doses of MMI (8 or 16 mg/kg body weight/day) or amitrole (25 or 50 mg/kg bw/day) from gestational day (GD) 7 to pup day (PD) 16, with BRB-seq performed for both life stages, specifically GD21 and PD16. Both MMI and amitrole caused significant changes to the testis transcriptome, seen particularly at PD16, with 313 differentially expressed genes (DEGs) defining a shared TH-mediated profile. Additionally, amitrole exposure resulted in a distinct profile of 1,517 DEGs, suggesting compound specific effects beyond TH disruption. This study underscores the potential sensitivity of transcriptomic profiling in detecting early tissue disruption under toxicological conditions, in this case testis disruption under hypothyroid state, offering critical insights for chemical risk assessment beyond histopathological endpoints.

Exposure to environmental pollutants during key stages of development increases the risk of disease later in life. One such toxicant with growing evidence of this response is the air pollutant, ozone (O3). Exposure to O3 during the implantation receptivity period in rats affects the metabolic status of offspring at adolescence, which may increase their susceptibility to subsequent environmental exposures. Herein, we studied the impacts of maternal O3 exposure on postnatal systemic responses to O3 in male and female offspring. Following peri-implantation O3 exposure (0.8 ppm for 4 hours/day on gestation days 5 and 6), offspring were exposed to O3 for 1 day/week on postnatal weeks 5-7. After the final exposure, metabolic effects were analyzed by circulating hormones and clinical chemistries, as well as hepatic lipid status and transcriptomic alterations. By and large, male offspring from O3-exposed dams were more greatly impacted than those from air-exposed dams. This included increased hepatic lipid mobilization, increased circulating glucose, and a robust number of differentially expressed genes (2,348). Interestingly, many of these transcriptomic differences were attributed to maternal O3 exposure, with 1,741 of these genes sharing directional similarity with postnatally exposed air littermates. Females, on the other hand, reported minimal baseline effects of maternal O3 exposure (108). However, postnatal O3 exposure in female offspring substantially increased these differences to 947 genes. Collectively, this work supports the growing evidence that early pregnancy exposure to O3 alters the metabolic development of the offspring. Furthermore, postnatal exposure to environmental stressors reveals hepatic susceptibilities that are sexually dimorphic.

Hematopoietic stem and progenitor cells (HSPC) produce all cells of the blood and immune system in a process known as hematopoiesis. During infection, there is an increased demand for immune cells which causes HSPC to rapidly and transiently modify cellular output, a response described as emergency hematopoiesis. Small molecules from the host environment may contribute to signals that regulate emergency hematopoiesis, providing a means to influence important processes during infection. Environmental exposures have long been associated with altered immune responses in human population and experimental studies. Specifically, chemicals that bind the aryl hydrocarbon receptor (AHR) modulate immune responses in a broad range of contexts, including during viral infection. Separate studies have shown that AHR signaling also influences steady-state hematopoiesis. Using two different AHR ligands, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2-(1H-indol-3-ylcarbonyl)-4-thiazole-carboxylic acid methyl ester (ITE), we characterized the impact of AHR activation on the proportion of HSPC and lineage-committed progenitor cells over the course of an influenza A virus infection in mice. AHR activation via these two ligands had a distinct impact on HSPC yet affected monocytes in the blood and lung similarly. For example, AHR activation with TCDD, but not ITE, increased myeloid-biasing among HSPC. However, the frequency of monocytes in the lung was reduced by either TCDD or ITE treatment. Using Vav1CreAhrfxfx mice, we showed that these effects depend on AHR expression in hematopoietic cells. Collectively, these findings highlight the differential effects of AHR ligands and their role in regulating emergency hematopoiesis in response to a common respiratory pathogen.

A chronic bioassay investigating radiofrequency (RF) carcinogenicity, intentionally designed to be conducted simultaneously in Korea and Japan, using the same research protocol and experimental environment. The study aimed to assess the potential carcinogenicity of Code Division Multiple Access (CDMA)-modulated 900 MHz RF signals at a whole-body specific absorption rate (SAR) of 4 W/kg, which is the reference level of the international human safety guideline, and to verify the key findings from the National Toxicology Program (NTP) study at that SAR level. Two reverberation chamber systems were used for RF exposures, and the same study protocols were followed. Male Harlan Sprague-Dawley (Hsd: Sprague Dawley® SD®) rats were randomly assigned to cage-control, sham-exposed, or RF-exposed groups. The exposure started on gestational day 5 and lasted for 18 hours and 20 minutes each day, with 10-minute on/off cycles. The project included a 28-day toxicity study, a 2-year carcinogenicity study, and a 14-week genotoxicity test. Histopathological evaluations were conducted in a partially blinded manner. The results were independently analyzed and submitted separately based on each country's research findings. In the Korean study, no statistically significant changes in tumor incidence or survival rates were observed. No significant RF-related effects were detected in the heart, brain, or adrenal glands. No changes in body temperature. Genotoxicity tests showed no evidence of DNA damage or mutation. In conclusion, the Korean part found that long-term exposure to CDMA-modulated 900 MHz RF was neither carcinogenic nor genotoxic at a SAR of 4 W/kg in male rats.

The potential carcinogenic and genotoxic effects of radiofrequency electromagnetic fields, particularly those emitted by mobile communication systems, have raised public health concerns. A previous study by the U.S. National Toxicology Program suggested increased incidences of gliomas and cardiac schwannomas in rats exposed to high levels of RF radiation. To evaluate these findings, an international collaborative study was initiated between Japan and Korea. Male Hsd: Sprague Dawley® SD® rats were exposed to 900 MHz CDMA-modulated RF-EMFs at a whole-body specific absorption rate of 4 W/kg for 18 hours and 20 minutes daily over two years. The study included a 28-day preliminary toxicity study, genotoxicity assays (alkaline comet and micronucleus tests), and a two-year carcinogenicity assessment. All procedures followed OECD guidelines and Good Laboratory Practice. No statistically significant increases in the incidences of neoplastic or non-neoplastic lesions were found in any major organ, including the brain, heart, and adrenal glands. Genotoxicity assays revealed no evidence of DNA damage or chromosomal aberrations in RF-exposed rats. A higher survival rate in the RF-exposed group, likely due to lower body weight and food consumption, was observed. This study performed in Japan, jointly planned and executed by Japan and Korea, provides strong evidence that long-term exposure to 900 MHz RF-EMFs did not produce reproducible carcinogenic or genotoxic effects in male rats. Combined with data from the Korean counterpart study, these results are expected to contribute to future international assessments of the carcinogenic potential of electromagnetic radiation.

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 non-linear. 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 two 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.

Per- and Polyfluoroalkyl Substances (PFAS) are a diverse class of highly fluorinated persistent synthetic chemical pollutants. Major routes of human exposure include ingestion of contaminated drinking water and foods including dairy. Consumption of PFAS-contaminated milk and dairy is especially concerning for infants and children who are particularly sensitive and most highly exposed. Here we report findings of quantitative analysis of PFAS binding to β-lactoglobulin (β-Lg), the major whey protein in bovine milk, using differential scanning fluorimetry to determine binding affinities for 17 PFAS; except for uncharged fluorotelomer alcohols, β-Lg bound each PFAS congener tested, supporting a key role of charged functional groups in binding. The perfluoroalkyl carboxylic acid trifluoroacetic acid (TFA) bound with lowest affinity (Kd = 8.6 mM) and long chain congeners PFNA, PFDA, and PFUnDA bound with highest affinities. Evidence of significant cooperative binding was found for TFA, PFDA, PFUnDA, and PFOS. Molecular docking was used to define molecular mechanisms of PFAS binding by β-Lg and across the calycin super family of lipocalins and fatty acid binding proteins. All calycins were predicted to bind PFAS in the calyx domain with ΔG of binding ranging from -5.3 to -9.4 kcal/mol, revealing that the binding affinity for many PFAS are greater than those for binding albumin. In total, this study has identified the calycin protein superfamily as PFAS binding proteins, most of which have well-characterized functions related to key endocrine and toxicological pathways associated with the adverse consequences of PFAS exposure.

There is a critical need to understand pathophysiological mechanisms involved in injury from acute chlorine gas (Cl2) exposure. Limited information is available regarding time course and mechanisms of injury after acute Cl2 exposure due to lack of human clinical data and limited fidelity of pre-clinical animal models. We designed and integrated a Cl2 exposure platform to generate and deliver precise concentrations of Cl2 to a microfluidic human airway-on-a-chip microphysiological system in vitro model. Chemical, biological, structural and functional airway-on-a-chip responses to Cl2 exposure were characterized across multiple concentrations, exposure times and post-exposure timepoints. Transcriptomics and metabolomics analyses delineated key molecular, cellular, and physiological pathways involved in acute response to Cl2 exposure. This work represents a significant advancement towards high-throughput, human-relevant characterization of pulmonary toxicants and medical countermeasure development, addressing critical gaps in toxicology modeling while reducing reliance on animal studies.