Archives of Toxicology最新文献

Myopericarditis requiring emergency care or hospitalization after COVID-19 mRNA vaccination occurs most frequently in adolescent males. In the acute phase, vaccine-associated heart inflammation is characterized by elevated cardiac biomarkers (troponin, B-type natriuretic peptide), electrocardiographic abnormalities, abnormal cardiac magnetic resonance imaging, elevated interleukins and chemokines, expansion of activated cytotoxic T lymphocytes, and monocyte dysregulation. This adverse event may occur one or two days after the first injection but is far more frequent after the second, suggesting contributions from trained innate immunity and/or cumulative dose effects. A recent mouse study in this journal reported dramatic increases in both cardiac biomarkers two days after the second dose of lipid nanoparticles (LNPs) containing mRNA coding for the Omicron spike, despite absence of histopathological heart damage at 14 days-even after intravenous administration. Here, these findings are discussed in the context of human observations and additional mouse experiments. I propose that endothelial cells (ECs) of the myocardial microvasculature are a preferred off-target for LNPs because of the unique features of myocardial anatomy and perfusion. Endothelial injury via toll-like receptor 4 (TLR4) activation by ionizable lipids and/or endosomal rupture may represent an initiating step ("endothelitis"), followed by recognition of spike-derived peptides presented by ECs to activated monocytes and T lymphocytes. The potential role of the Wuhan spike protein in establishing a trained innate immunity phenotype, and species differences in TLR sensitivity, are considered.

Although intoxication with hexavalent chromium [Cr(VI)] compounds can be fatal to humans, reliable data on chromium toxicokinetics are largely missing. We report on a rare case of intravenous Cr(VI) poisoning and its impact on the scientific understanding of chromium toxicokinetics and red blood cells' (RBCs') lifespan in the human body. The approximate amount of injected chromium was between 0.33 and 0.66 g. Laboratory findings were collected over a half-year period from the time of injection. We monitored kidney function, liver function, RBC parameters, and chromium concentration in RBCs, plasma, and urine. In all samples, the total chromium concentration was quantified by inductively coupled plasma-mass spectrometry. By injecting Cr(VI) into his vein, the patient inadvertently labeled all his RBCs with chromium. This gave us the unique opportunity to calculate the RBC lifespan rather than just to estimate it. Based on RBC breakdown rates, the average lifespan was calculated to be 111 days, and the maximum lifespan to be 141.4 days. At about 24 weeks post-injection, the RBC chromium concentration approached background-exposure values, whereas chromium in plasma reached a plateau considerably higher than the reference value. These results confirm that there is a long-term storage compartment for chromium in the human body, which releases chromium into plasma but leaves the RBC chromium concentration unaffected. Therefore, this singular case of Cr(VI) poisoning provides us with the long-awaited scientific proof that chromium in the RBC fraction is a specific monitoring parameter for exposure to the carcinogen Cr(VI) in occupational and environmental settings.

This Letter to the Editor addresses the recent step by the International Agency for Research on Cancer (IARC) to reclassify pure talc from Group 2B "Possibly carcinogenic to humans" to Group 2A "Probably carcinogenic to humans". This change was made by IARC not based on any new data, but by reassessing previous studies, including an inhalation study on rats and mice performed in the 1980s under the auspices of the National Toxicology Program (NTP). The NTP study, however, found evidence of tumorigenicity in rats only, but not in mice. This contradicts the toxicological principle of "at least two species" for extrapolating carcinogenicity status from animals to humans. Benign and malignant pheochromocytoma, a rare condition identified in the adrenal medulla of rats in multiple NTP studies, played a special role in the IARC talc reclassification, being evaluated as the "unusual" finding requiring a precautionary approach. The Letter argues that combined benign, malignant, and complex pheochromocytoma in rats is irrelevant for the assessment of talc carcinogenicity in humans. However, with the exclusion of pheochromocytoma argumentation, the need for talc reclassification appears to be highly questionable.

Phencyclidine (PCP), historically known as "angel dust," and its analogues (3-HO-PCP, 3-MeO-PCP, 4-MeO-PCP, 3-HO-PCE, 3-MeO-PCE, 4-MeO-PCE) are dissociative new psychoactive substances with high abuse potential and limited experimental safety data. An integrated in silico workflow (STopTox, admetSAR 3.0, ADMETlab 3.0, ACD/Labs Percepta, Toxtree, ProTox 3.0, OCHEM, TEST, VEGA QSAR) was applied to profile acute toxicity and key hazard domains. Across platforms, rat oral LD₅₀ values for PCP-type analogues were consistently in the ~ 200-630 mg/kg range (Percepta 210-800 mg/kg, TEST 197-628 mg/kg, VEGA 278-368 mg/kg, ProTox ~ 348-404 mg/kg), indicating moderate acute toxicity by the oral route; substantially lower LD₅₀ values were predicted for intravenous exposure in mice (~ 25-59 mg/kg). Qualitative models (STopTox, ADMETlab, admetSAR) classified all compounds as acutely toxic by the oral route (e.g., STopTox oral toxicity confidence ~ 77-92%) and commonly predicted inhalation/dermal risks depending on the analogue; admetSAR assigned EPA Category III for acute oral toxicity. Organ-specific effects (Percepta; ADMETlab) highlighted the lungs, liver, and blood as prominent targets (e.g., lungs 0.89-0.93, liver up to 0.91, blood up to 0.85), with gastrointestinal involvement (up to 0.82) and generally lower kidney probabilities (~ 0.09-0.70). Cardiotoxicity signals included predicted hERG inhibition with Percepta IC₅₀ ~ 4.9-12.3 µM and high probabilities of hERG blockade in ADMETlab/admetSAR, supporting potential QT-prolongation risk. Genotoxicity predictions were consistently negative across Percepta, OCHEM, ADMETlab, admetSAR, and VEGA. Eye/skin irritation potential was notable for phenolic analogues, with Percepta indicating high probabilities for 3-HO-PCP and 3-HO-PCE (eye ~ 88-90%, skin ~ 96%), while other tools showed model-dependent variability. Endocrine screening suggested at most weak-to-moderate ER-α interactions, with the highest probability for 3-HO-PCP (LogRBA >  - 3). Overall, convergent multi-tool evidence indicates moderate acute toxicity, cardiotoxicity signals, and multi-organ risk for PCP analogues, while mutagenicity appears unlikely. These results provide mechanistic and quantitative context to inform clinical management, forensic interpretation, and risk assessment of this NPS class.

Triclosan (TCS), a broad-spectrum lipophilic antiseptic, is frequently found in household and healthcare supplies. Its increased use during the COVID-19 pandemic has led to significant accumulation in soil and aquatic environments. In humans, TCS predominantly accumulates in the liver, while little is known about the molecular processes promoting TCS-induced hepatic damage. Adverse outcome pathways (AOPs) offer a structured toxicological framework linking molecular initiating events to adverse health outcomes. To examine how TCS exposure relates to liver fibrosis, we developed an AOP framework and established an offspring rat model subjected to lifelong TCS exposure. Through the milk and placenta, the offspring rats were exposed to TCS. After weaning, they received 0, 10, and 50 mg/kg doses until day 60. Our findings indicate that lifelong TCS exposure increased hepatic transforming growth factor-β (TGF-β1) levels and then modulates the advanced glycation end products (AGEs) and their receptor (RAGE) pathway (AGEs-RAGE pathway) to promote collagen production, causing extracellular matrix deposition and hepatic fibrosis. The reliability of the AOP framework was validated by the significant decrease in the markers linked to fibrosis-related expression following this two-part inhibition. This framework received a "high" rating based on the Organization for Economic Cooperation and Development (OECD User Manual) assessment guidelines, by integrating this framework with in vitro and in vivo experiments. These findings offer a basis for future risk assessment and therapeutic strategies targeting TCS-induced liver fibrosis.

Desalkylgidazepam, an active gidazepam metabolite, first appeared on the illicit drug market in 2022 and has been detected in polydrug intoxication cases. Since both benzodiazepines and their metabolites can result from gidazepam metabolism, it is important to identify markers that specifically indicate consumption of each compound. We therefore investigated the human metabolism of gidazepam and desalkylgidazepam by incubating them with human hepatocytes and analyzing the resulting samples, along with human blood from a confirmed desalkylgidazepam-positive case, using liquid chromatography-high-resolution mass spectrometry. To further assess their pharmacological profile, we examined the activity of gidazepam, desalkylgidazepam, and their potential (3R)- and (3S)-hydroxy metabolites at γ-aminobutyric acid A (GABA_AR) and 18 kDa translocator protein (TSPO) receptors in silico, using AutoDock Tools and UCSF Chimera. Gidazepam was metabolized through N-desalkylation (yielding desalkylgidazepam), N-acetylation, and N-glucuronidation. Conversely, desalkylgidazepam was subjected to hydroxylation and subsequent O-glucuronidation reactions. Notably, gidazepam demonstrated a lower affinity at GABA_AR's prominent α₁/γ₂ site compared to desalkylgidazepam and its (3R)- and (3S)-hydroxy metabolites. However, its interaction with the transmembrane domains of the α₁β₂ subunit may account for its anxiolytic effects. For the TSPO receptor, gidazepam and 3-hydroxy desalkylgidazepam metabolites showed higher binding affinity, whereas desalkylgidazepam did not bind to TSPO. Our findings suggest blood markers specific to gidazepam, namely gidazepam-N-glucuronide and N-acetyl gidazepam, are essential for confirming gidazepam consumption. In addition, in silico modelling supports the hypothesis that gidazepam functions as a prodrug via GABA_AR and as an agonist at TSPO. Further research is necessary to clarify designer benzodiazepine activity at TSPO.

Fluoride plays a dual role in dental health-preventing caries at optimal levels but causing fluorosis when excessive. While most animal studies focus on young mice, age-related susceptibility to fluoride remains poorly understood. This study presents the first comprehensive analysis of developmental stage-dependent differences in fluoride toxicity, focusing on enamel formation and systemic fluoride clearance. Male C57BL/6J mice-adolescent (5-9 weeks) and mature (16-20 weeks)-were exposed to fluoride in drinking water (0, 50, 100, or 125 ppm) for 6 weeks. Adolescent mice developed pronounced dental fluorosis, characterized by chalky white incisors, elevated Quantitative Light-induced Fluorescence (QLF) values, reduced enamel microhardness, and lower enamel mineral density (EMD). Histological analysis revealed disrupted ameloblast morphology, reduced KLK4 expression, and aprismatic enamel, with more severe effects in adolescents. In contrast, mature mice exhibited minimal changes in QLF, enamel hardness, and EMD. Systemic fluoride analysis showed significantly lower serum and urinary fluoride levels in adolescent mice compared to mature mice, indicating reduced excretion and increased tissue accumulation. These findings demonstrate that younger mice are more vulnerable to fluoride-induced enamel defects due to lower clearance than mature mice. This study provides critical evidence of age-related differences in fluoride toxicity, revealing heightened vulnerability during developmental stages. Our findings have significant public health implications, supporting the need for age-specific fluoride exposure guidelines to balance caries prevention and developmental fluoride toxicity.

Drug biotransformation and bioactivation play a pivotal role in drug discovery, driving the development of analytical methods to investigate xenobiotic metabolism. However, the identification of drug metabolism products (i.e., drug metabolites) remains challenging. Drug metabolites are difficult to predict, and they are often missed without prior knowledge of the drug's metabolic fate. Untargeted approaches overcome this requirement, but demand strategies for metabolite identification. In this study, we developed a computational workflow, using high resolution LC-MS/MS metabolomics data, integrating BioTransformer and SIRIUS for the prediction and putative identification of drug metabolite structures. We challenged our workflow to the analysis of human metabolites from 6 well-known drugs, administered to primary human hepatocytes and human liver microsomes: amitriptyline (10 µM), carbamazepine (12.5 µM), cyclophosphamide (20 µM), fipronil (20 µM), phenytoin (50 µM), and verapamil (6 µM). Of the drugs' metabolites, 62-100% were found using this computational approach. Furthermore, 4 new metabolite structures (1 amitriptyline metabolite and 3 verapamil metabolites) were proposed using de novo predictions in SIRIUS. This strategy proved efficient in accelerating the study of drug metabolism, potentially avoiding tedious manual metabolite identification. In sum, we demonstrate that this computational workflow holds potential in automating metabolite identification, expanding metabolite coverage, and elucidating metabolites of newly developed drugs.

FOXN family genes (FOXNs) have a significant role in the progression of various malignancies; nevertheless, the relationship between their genetic variations and the risk of bladder cancer is yet insufficiently comprehended. This study included 580 bladder cancer patients and 1,101 healthy controls, evaluated for 8,695 single nucleotide polymorphisms (SNPs) in FOXNs. The rs10484024 T > C variant in FOXN3 was identified as a significant risk factor for bladder cancer (OR = 1.18, 95% CI: 1.02-1.36, P = 2.72 × 10^- 2). Further investigation reveals a strong interaction between this locus and smoking (P_interaction = 3.50 × 10^- 2), and bladder cancer risk is much higher in smokers carrying the C allele (OR = 1.93, 95% CI: 1.39-2.71, P = 1.13 × 10^- 4). Functional annotation results suggest that rs10484024 is likely reducing FOXN3 expression by affecting the remote regulation of RNA-binding protein binding sites and enhancers/promoters. The TCGA study, in conjunction with GSE3167, confirmed that the dysregulation of FOXN3 expression was associated with altered mutation frequency in KMT2C somatic cells and the modulation of cell cycle-related pathways. The data suggest that rs10484024 may promote bladder cancer by regulating FOXN3 expression and worsening cell cycle dysregulation and somatic mutation accumulation. This study established, for the first time, an association between genetic variation in the FOXN3 gene and bladder cancer risk, demonstrating a substantial interaction with smoking, suggesting that FOXN3 may serve as a novel biomarker and intervention target for bladder cancer.

Human in vitro liver tissue models have evolved to maintain hallmarks of hepatocellular function for extended periods with potential to model aspects of cholestasis for drug and chemical safety applications. Microphysiological systems (MPS) have been suggested as promising new approaches to model liver physiology and predict chemical-induced cholestasis in humans. This study comprehensively compared both basal function and toxicant-induced effects in 2D cultures and three liver MPS (i.e., 2-lane OrganoPlate, 3-lane OrganoPlate and PhysioMimix LC12) that were seeded with either HepaRG cells, primary human hepatocytes (PHH), or human induced pluripotent stem cell (iPSC)-derived hepatocytes. PHH and iPSC-derived hepatocytes (iHeps) were tested up to 7 days while HepaRG were evaluated over 30 days. Albumin, urea, CYP3A4 activity, and bile acids were measured. HepaRG and PHH showed comparable function in 2D and PhysioMimix LC12, with albumin higher for HepaRG and urea higher for PHH. HepaRG maintained production of biomarkers for up to 30 days in both 2D and PhysioMimix LC12. In both OrganoPlate models, HepaRG produced higher levels of albumin and urea as compared to iHeps; still, HepaRG function in OrganoPlate was lower than that in 2D or PhysioMimix LC12. Bile acid synthesis (after 7 days) was much higher with PHH in the PhysioMimix LC12 as compared to 2D PHH or 2D HepaRG. Upon exposure to cholestatic agents (bosentan, 2-octynoic acid, α-naphthyl isocyanate), robust CYP3A4 induction was observed in HepaRG and PHH treated with bosentan and α-naphthylisocyanate. Only in PhysioMimix LC12, both HepaRG and PHH, all compounds elicited decreased bile acid release into cell culture medium, a biomarker for cholestasis. In summary, the hepatocyte functional markers (CYP3A4, albumin, urea) were comparable between PHH and HepaRG in 2D and PhysioMimix LC12 MPS. However, the effects of cholestatic agents on PHH and HepaRG, specifically, bile acid release were detected only in the PhysioMimix LC12 with PHH showing more consistent responses compared to HepaRG.