Chemical Research in Toxicology最新文献

Toxicological research is facing a major transition from animal models into in vitro and in silico models to improve the cost-effectiveness of the testing process, shorten the timeline for primary screening of chemicals, and better align with the 3Rs principles to reduce animal suffering. In this work, structure–activity relationships were developed based on structural alerts (SAs) that flag the ability of chemicals to trigger specific molecular initiating events (MIEs) upstream of five adversities (cholestasis, steatosis, kidney tubular necrosis, cognitive functional defects, and neural tube closure defects). Twenty-nine protein targets linked to MIEs were identified from published adverse outcome pathway networks, while bioactivity data for chemicals against such targets were collected from ChEMBL 35 database. SARpy 2.0 included in the novel ΔQSAR (DeltaQSAR) software was used to extract rulesets, i.e., collections of structural alerts codifying for protein bioactivity. The rulesets were evaluated using an external test set to assess their real-life predictivity. Good external validation performance was achieved for 22 out of 29 rulesets that returned balanced accuracy ≥ 70% and coverage ≥ 70%, confirming that these rulesets can be used for high-throughput as well as preliminary testing of chemicals. Moreover, combining structure–activity relationship with the adverse outcome pathway concept provides a mechanistic basis to the prediction suggested by the rulesets.

Triclosan (TCS), a synthetic compound initially marketed as a broad-spectrum antibacterial agent, poses significant threats to the environment, animal, and human health due to its inherent toxicity and improper discharge. This study first comprehensively assessed the environmental and biological toxicity of TCS. Subsequently, an integrated approach combining network toxicology, molecular docking, and in vivo experiments was employed to analyze and experimentally validate. For the first time, the mechanisms underlying TCS-induced liver injury in weaned piglets. Results identified 31 major targets associated with TCS-induced liver injury. Molecular docking confirmed strong binding affinity between TCS and the top 10 MCC-ranked core targets. Factor-gene and miRNA-gene regulatory networks were constructed for these core targets. Further GO and KEGG analyses revealed significant enrichment of TCS hepatotoxicity targets in biological processes, including redox regulation, and multiple signaling pathways. Validation via in vivo experiments in weaned piglets demonstrated that TCS exposure significantly induced liver damage and histopathological alterations. It disrupted hepatic redox homeostasis, evidenced by significantly decreased T-AOC, SOD, CAT, and GSH levels, alongside increased MDA levels. Furthermore, TCS significantly upregulated the expression of the Rap1-PI3K/AKT, HIF-1/VEGF, and Ras-MAPK signaling pathways. This study provides the first evidence that TCS exerts hepatotoxicity by inducing hepatic oxidative stress and aberrant activation of multiple signaling pathways. The findings offer novel data for the comprehensive toxicological assessment of TCS, contribute to safeguarding animal and human health, and propose a framework for the integrated risk assessment of similar environmental contaminants.

Exposure to respirable particles such as multiwalled carbon nanotubes (MWCNTs) can provoke acute lung inflammation and tissue injury, potentially progressing to chronic disease. Lipid mediators (LMs), including proinflammatory and pro-resolving species, play a critical role in regulating this process. This study investigated LM biosynthesis in acute lung inflammation induced by fibrogenic MWCNTs. Adult C57BL/6J mice were exposed to MWCNTs (Mitsui-7; 1860.4 μg/kg) via oropharyngeal aspiration. Lung tissues collected 24 h postexposure exhibited neutrophil infiltration, elevated inflammatory cytokines, and tissue damage. Enzymes involved in prostanoid synthesis─phospholipase A2, cyclooxygenase-2, and prostaglandin E synthase─were significantly upregulated. Lipidomic profiling was performed by using C18 spin column enrichment and UPLC-MS/MS. MWCNT exposure significantly increased the levels of prostanoids (PGE2, PGD2, PGF2α, thromboxane B2) and hydroxyeicosatetraenoic acids (5-, 12-, 15-HETE). Elevated levels of protectin DX, 14(S)-, and 17-HDHA derived from docosahexaenoic acid, and 12-, 15-, and 18-HEPE derived from eicosapentaenoic acid were also observed. In vitro, MWCNTs induced intracellular lipid accumulation in macrophages. These findings reveal rapid activation of LM biosynthetic pathways, particularly those producing proinflammatory prostanoids, in mouse lungs following nanoparticle exposure. The study underscored the utility of lipidomic profiling for mechanistic insights into nanoparticle-induced sterile inflammation and toxicity in limited tissue samples.

Cadmium (Cd), like the other group 12 elements (Zn and Hg), has a high affinity for sulfur (S) and selenium (Se), a property that strongly influences its adverse biological effects. Although the symptoms of Cd toxicity are diverse, a common denominator is found in oxidative stress, resulting in the disruption of redox balance in cells and the proliferation of reactive oxygen species (ROS) and harmful radicals. Methylcadmium (CH₃Cd⁺) is a convenient model to study Cd pro-oxidant activity in silico. In this work, the effect of CH₃Cd⁺ on the peroxy-reducing potential of cysteine (Cys) and selenocysteine (Sec) is investigated at the ZORA-BLYP-D3(BJ)/TZ2P level and compared to our current knowledge on the analogous molecular aspects of methylmercury’s toxicity (CH₃Hg⁺). Molecular docking simulations indicate that CH₃Cd⁺ binds favorably to the catalytic sites of the GPx1 and TrxR1 enzymes. The short distances between the metal and Sec suggest that a nucleophilic attack by Se to Cd leading to the inhibition of the enzyme is indeed possible. Methylcadmium pro-oxidant activity is─if not equal─only slightly inferior to that of methylmercury.

Balkan endemic nephropathy (BEN) is a chronic kidney disease associated with the consumption of aristolochic acids (AAs) through contaminated food sources. AAs are known to form DNA adducts that are implicated in tumorigenesis and kidney fibrosis. Given the sensitivity of DNA adduct formation to dietary factors, this study aimed to investigate the impact of various dietary practices on AA-DNA adduct formation, thereby assessing the risk of developing BEN. We quantified AA-DNA adducts in DNA extracted from the kidneys and livers of mice subjected to high-fat, high-protein, high-sucrose, and high-salt diets, utilizing a highly sensitive liquid chromatography–tandem mass spectrometry method combined with stable isotope dilution. Our results demonstrated that unbalanced diets significantly elevated the formation of DNA adducts from AAs. Notably, mice fed high-fat diets exhibited increases in adduct levels of 71 and 114% for diets containing 17 and 25% fat, respectively. Mice on a 20% sucrose diet showed an 80% increase in adduct levels compared to those on a standard diet. Further investigations using gut sacs from the small intestines of these mice revealed that the increased level of DNA adduct formation was primarily attributed to enhanced intestinal absorption. Additionally, we observed that drinking alkaline water reduced adduct levels by 30% compared to tap water, likely by decreasing AA absorption. In contrast, commonly used dietary supplements, such as vitamin C and cysteine, significantly increased AA-DNA adduct levels by enhancing the activity of enzymes involved in the metabolic activation of AAs. These findings highlight the critical role of a balanced diet in mitigating the risk of BEN and suggest that alkaline water consumption may serve as a protective strategy for individuals living in AA-contaminated regions.

Trimethoprim (TMP) is an essential antibiotic used in combination with sulfamethoxazole to treat and prevent bacterial infections. Idiosyncratic adverse drug reactions (IADRs) to TMP occur in a small but significant percentage of the treatment population. TMP IADRs manifest as mild to life-threatening skin rashes, pulmonary failure, or hepatotoxicity. Currently, our incomplete knowledge of TMP metabolism is a barrier to understanding the TMP-IADR etiology. In this study, we investigated TMP phase I and II metabolism in tissues involved with IADRs including liver, lung, and skin using human s9 subcellular fractions. Triple-quadrupole and quadrupole-time-of-flight mass spectrometry were used to compare trimethoprim phase I and phase II metabolism in these organ systems and to detect identified metabolites in the urine of subjects taking and tolerating TMP. In this study, we found that phase I TMP metabolites are formed predominantly in the liver, and phase II TMP metabolites are formed differentially in extrahepatic tissues. This characterization of TMP metabolism in affected tissues is an important step toward a better understanding of the mechanisms involved in the TMP IADRs.

Histones react with one of the most abundant endogenous DNA lesions, the apurinic/apyrimidinic (abasic, AP) site, to form reversible but long-lived Schiff base DNA–protein cross-links at 3′-DNA termini (3′-histone-DPCs). These DPCs need to be repaired, because 3′-hydroxyl groups are required for DNA repair synthesis and strand ligation. We previously identified three human enzymes, including tyrosyl-DNA phosphodiesterase 1, AP endonuclease 1 (APE1), and three-prime repair exonuclease 1 (TREX1), that can repair chemically synthesized adducts that closely resemble the proteolyzed Schiff base 3′-histone-DPCs. Here, we report another two human enzymes, APE2 and TREX2, that have a similar function.

Per- and polyfluoroalkyl substances (PFAS), common environmental contaminants, can cause cardiotoxic effects particularly during fetal development. However, the effect of combined PFAS exposure, which more closely reflects real-world environmental conditions, remains poorly understood. In this study, human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) were exposed to three common PFAS compounds─perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and perfluorodecanoic acid (PFDA)─individually or in combination (20–200 μM; consistent with serum levels reported in occupationally exposed populations). Compared with single compounds, combined PFAS exposure induced synergistic cytotoxicity, significantly reducing hiPSC-CM viability after 5 or 10 days. Sublethal combined exposure for 10 days altered mitochondrial membrane potential and mitochondrial content in a dose-dependent manner and shifted cysteine metabolism, potentially reflecting adaptation to oxidative challenge. After 14 days, combined PFAS increased vimentin, a fibroblast marker, and reduced NKX2.5, α-actinin, and cardiac troponin T, key markers of cardiomyocytes, as detected by immunocytochemistry. Proteomics further showed enrichment of pathways in extracellular matrix organization, cholesterol metabolism, and antioxidant defense, as well as downregulation of mitochondrial proteins. Consistent with changes in protein profiles related to oxidative stress and bioenergetic impairment, exposure of hiPSC-CMs to combined PFAS also increased the level of mitochondrial superoxide, reduced ATP content, and decreased cellular respiration. Together, these data demonstrate that PFAS mixtures drive mitochondrial dysfunction, oxidative stress, metabolic changes, and extracellular matrix remodeling in hiPSC-CMs, underscoring the importance of evaluating PFAS mixtures to better understand cardiac risks from environmental exposure.