Toxicological Sciences最新文献

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.

Neutrophils play a complex role in the pathogenesis of chronic liver disease and have been linked to both liver damage and injury resolution. Recent reports propose that neutrophils drive liver injury and fibrosis through the formation of neutrophil extracellular traps (NETs). This study tests the hypothesis that the enzyme peptidyl arginine deiminase-4 (PAD4) drives NET formation and liver fibrosis in experimental chronic liver injury. Wild-type (PAD4+/+) and PAD4-deficient (PAD4-/-) mice were chronically challenged twice weekly with carbon tetrachloride (CCl4, 1 ml/kg, i.p) or vehicle (corn oil) for 6 weeks, and samples were collected 24 h after the final challenge. In separate studies, mice were challenged once, and samples were collected 24 to 48 h later. Circulating NET biomarkers (e.g. myeloperoxidase-DNA complexes) were elevated in chronic CCl4-challenged wild-type mice compared to vehicle, though surprisingly, intrahepatic NETs were rarely observed. In contrast to our hypothesis, PAD4 deficiency did not eliminate circulating NET markers in chronic challenge. Furthermore, PAD4 deficiency did not impact liver fibrosis assessed by picrosirius red labeling or the myofibroblast marker α-smooth muscle actin but caused a modest, sex-specific decrease in hepatic collagen type I immunolabeling. Interestingly, plasma NET biomarkers and intrahepatic NETs were both increased following acute CCl4 challenge in a PAD4-dependent manner. Furthermore, PAD4 deficiency reduced coagulation activity after 24 h and decreased hepatocellular necrosis 48 h after challenge. Our studies ultimately suggest that PAD4 affects liver injury uniquely, depending on the stage of disease and that mechanisms of NET formation may occur independent of PAD4 in chronic liver injury.

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.

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.

Cannabis use typically starts in early to mid-adolescence. Δ9-tetrahydrocannabinol (THC), the primary psychoactive component of cannabis, targets cannabinoid receptors (CBRs) to exert its pharmacological effects. Expression of CBRs has been observed in human and rodent testes, but their potential role in the control of reproductive function remains unclear. We aimed to elucidate how THC exposure during adolescence or young adulthood affects the reproductive health of males. C57BL/6N male mice were given THC (5 mg/kg) or vehicle, once daily by intraperitoneal injection from postnatal day (PND) 30 to PND 43 (adolescent exposure) or PND 70 to PND 83 (adult exposure), and testes were harvested at PND 70 and PND 110, respectively. Results showed that CBRs (CB1R and CB2R) and enzymes that biosynthesize or inactivate the endocannabinoids anandamide-N-acylphosphatidylethanolamine phospholipase D or fatty acid amide hydrolase, respectively-are expressed in the mouse testis. THC exposure in adolescence decreased sperm numbers and increased seminiferous tubule degeneration in young adult testes, whereas adult exposure did not affect spermatogenesis and seminiferous tubule morphology. Both adolescent and adult THC exposure resulted in decreased plasma testosterone levels; however, only mice with adolescent THC exposure showed impaired steroidogenesis with dysregulated expression of steroidogenic acute regulatory protein and steroid 17-alpha-hydroxylase/17,20 lyase (CYP17A1). Our results support that adolescent THC exposure may cause testicular toxicity through direct and aberrant activation of CBRs in the testis. These studies show that the adolescent testis is more sensitive than the adult testis to THC-induced disruption of spermatogenesis.

Toxicology is shifting toward predictive, mechanism-based approaches that support quicker, more human-relevant risk assessments and reduce reliance on animal testing. Central to this shift are short-term in vivo studies enriched with omics endpoints, which provide early molecular indicators of toxicity. These data enable the derivation of molecular points of departure and other biologically anchored metrics that can inform potency ranking, hazard identification, and risk assessment. This commentary summarizes insights from the 2025 Society of Toxicology session of the same name and highlights the importance of aligning technical advances with regulatory needs. Next-Generation Risk Assessment (NGRA) is a safety evaluation approach that incorporates emerging tools such as in vitro methods, computational models, and omics data to inform decision-making for human health and the environment, while aiming to reduce dependence on traditional animal testing. NGRA frameworks, while potentially generic in principle, must be tailored to the specific regulatory requirements and exposure contexts of different product sectors, including pharmaceuticals, industrial chemicals, agrochemicals, and cosmetics. Short-term mechanistic animal studies serve as a bridge between traditional long-term animal testing and new approach methodologies. From a technical standpoint, the generation, analysis, and interpretation of omics data have matured considerably, bringing regulatory acceptance within reach. Remaining challenges include standardizing bioinformatics pipelines, building confidence through validation against apical endpoints, and expanding training. Addressing these gaps through collaborative science and flexible regulatory frameworks will be key to realizing the full potential of omics-enabled hazard profiles to support NGRA.

In the zebrafish larval toxicity model, phenotypic changes induced by chemical exposure can potentially be explained and predicted by the analysis of gene expression changes at sub-phenotypic concentrations. The increase in knowledge of gene pathway-specific effects arising from the zebrafish transcriptomic model has the potential to enhance the role of the larval zebrafish as a component of Integrated Approaches to Testing and Assessment (IATA). In this paper, we compared the transcriptomic responses to triphenyl phosphate between 2 standard exposure paradigms, the Zebrafish Embryo Toxicity (ZET) and General and Behavioral Toxicity (GBT) assays. The ZET assay represents a developmental model with chemical exposure from 6 to 120 h post fertilization (hpf), which covers organogenesis, whereas the GBT represents a juvenile model with exposure from 72 to 120 hpf, which occurs post-organogenesis. This comparison demonstrates both similarities and differences between the 2 assays. Although both models identified similar xenobiotic metabolism pathways, the difference in exposure window length and the time of transcriptomic sampling between the 2 methods also yielded unique sets of affected pathways, demonstrating their complimentary nature. Both data sets support previously described effects of triphenyl phosphate on aquatic and mammalian systems. This work validates and strengthens the use of both exposure paradigms and continues to demonstrate that zebrafish larvae are a valuable tool in the context of IATA toward reduced reliance on the use of higher vertebrate derived data for chemical risk assessment.

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.

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.