International Journal of Toxicology最新文献

Have you ever reflected on your career or other experiences and thought, if I knew 10 or 20 years ago, what I know now, it would have enabled me to do this or that better-or I would have had a different attitude or perhaps even taken a different path? This article presents the proceedings from the symposium entitled "I Wish I Had Known That! Impactful Guidance and Perspectives for a Fulfilling Career in Toxicology" held at the 2023 annual meeting of the American College of Toxicology. In this session, toxicology professionals reflected on the highlights of their careers, the most impactful advice/mentoring they received or wish they had received, and the characteristics that have been key components of their success. This session consisted of didactic talks from a diverse panel representing various career stages and backgrounds, followed by a panel discussion and the opportunity for the audience to ask questions. Using a structured approach, speakers actively engaged the audience, providing insights gained through their professional journeys. This article offers experiential-based insights to help guide individuals in achieving successful and fulfilling careers in toxicology, considering both professional aspirations and the integration of personal values with life goals.

Fueled by the identification and invention of novel gene delivery vectors, gene therapy efforts now hold promise for treating a wide range of diseases and are seen as a crucial part of growth for the biopharmaceutical industry. Currently, recombinant adeno-associated virus vectors (rAAVs) and lentiviral vectors (LVs) are the main vectors used in gene therapies that are approved or tested in human clinical trials. Meanwhile, ongoing research continuously reveals unprecedented knowledge of viral vectors on the host genome, which may subsequently affect the mutagenic and carcinogenic potential of these therapies. This article summarizes the content and addresses the commentary from the scientific symposium entitled "Mutagenesis and Carcinogenesis Risk Evaluation for AAV and Lentiviral Gene Therapies," conducted at the 43^rd Annual Meeting of the American College of Toxicology, November 2022 in Denver, CO. The objective is to summarize the current understanding of rAAV and LV related mutagenicity/carcinogenicity risk, describe the methods and interpretation of results to guide risk assessments, as well as the current regulatory landscape on the carcinogenicity and mutagenicity assessment of rAAV and LV gene therapy products.

Nucleic acid drug delivery with lipid nanoparticle (LNP) formulations has enabled the development of novel therapeutics and vaccines. LNP formulations are composed of both naturally occurring and synthetic lipid excipients. This perspective shares current practices in the nonclinical safety assessment of novel lipid excipients contained in LNP formulations and identifies gaps in current regulatory guidance on this topic. There is no globally harmonized regulatory guidance for the nonclinical safety assessment of novel excipients or guidance specific to safety testing of novel excipients in LNPs. Given the complexity of these LNP formulations, most nonclinical safety studies to support development are conducted with the drug product or with a LNP that contains non-active cargo. Three case studies (Onpattro^®, Comirnaty^®, and SpikeVax^®) highlight that specific assessments may differ depending on the encapsulated modality, the intended use (e.g., therapeutic versus preventative vaccine), dose, and frequency of dosing. These case studies also suggest that regulatory agencies are open to scientific rationale to justify why certain tests should or should not be performed. As more products are approved, it will be important to understand how precedents set for approved products can be leveraged and what additional unique strategies may be applied to ensure nonclinical safety assessments are predictive, relevant, and meaningful for human safety. Proactive alignment with regulatory authorities will be critical in this context, especially as new approaches are proposed. Guidance documents may need to be revised or created as more experience is acquired to reflect the unique considerations for these novel excipients.

Etomidate, an ultrashort-acting non-barbiturate sedative derived from imidazole, exerts potent inhibitory effects on the central nervous system. It is commonly employed for the induction of intravenous general anaesthesia or assisted anaesthesia. Recently, etomidate has emerged as an alternative to narcotics and novel psychoactive substances, leading to an increasing trend of abuse. Chronic overdose of etomidate can result in irreversible brain damage and various mental disorders. Severe cases may manifest as mental disturbances, behavioural disorders, self-mutilation and even death. The toxicological mechanisms of etomidate remain poorly understood. Additionally, there is limited information on the clinical symptoms and histopathological changes associated with etomidate poisoning and standardized detection methods for etomidate in blood, urine and hair are lacking. Consequently, further research on toxicological pathology and the development of reliable testing methods is crucial. This study reviews the metabolism, distribution, adverse reactions, poisoning manifestations, toxicology mechanisms and testing methods of etomidate.

Oral toxicity and toxicokinetic properties of human lactoferrin (LF) alpha produced in Komagataella phaffii (effera™) were investigated in adult Sprague-Dawley rats over a 28-day period under good laboratory practice conditions. Main study dosing used groups of 10 rats/sex/dose, and a secondary study evaluating toxicokinetic parameters used 6 rats/sex/dose. The vehicle control group received sodium citrate buffer, test groups received daily doses of 200, 600, and 2000 mg of effera™ per kg body weight, and the comparative control group received 2000 mg bovine LF (bLF)/kg body weight per day. T-cell-dependent antibody response against keyhole limpet hemocyanin and immunophenotyping of the spleen were performed as measures of immunotoxicity. Clinical observations, body weight, hematology, coagulation, clinical chemistry, urinalysis, immunotoxicity, gross necropsy, and histopathology were assessed. Toxicokinetic parameters were analyzed as an indication of LF bioavailability, and anti-LF antibody assays were conducted to detect antibodies produced against LF to measure immunogenicity. No treatment related toxicologically significant changes were observed. Based on the absence of toxicologically relevant changes, effera™ is well tolerated in rats at doses up to 2000 mg rhLF/kg/day, an amount ∼400 times that of the estimated daily intake at the 90th percentile proposed for human adult use.

The therapeutic window of antibody drug-conjugates (ADC) remains challenging due to safety issues such as interstitial lung disease (ILD) observed with specific deruxtecan-based ADCs. To avoid ILD, we designed M9140 by conjugating the maleimide-containing hydrophilic β-glucuronide linker to exatecan and our anti-CEACAM5 (CarcinoEmbryonic Antigen-related Cell Adhesion Molecule 5) specific antibody. Following repeated iv-infusion at 3 to 30 mg/kg of M9140 every 3 weeks, the pathological findings obtained in cynomolgus monkeys were confined to gastrointestinal and hematolymphoid tissues and resembled the toxicity of exatecan. At 24 mg/kg or higher, transient reductions in neutrophil and reticulocyte counts were observed with each dosing event along with reversible anemia throughout the study. The no observed adverse effect level was 24 mg/kg and the maximum tolerated dose was 30 mg/kg. The difference in toxicity by this small dose increment was correlated with a 2.5-fold difference in plasma exatecan exposure indicating antigen-independent toxicity. As anticipated, no lung toxicity was found with M9140 in these studies that were similar in study design to those used to confirm ILD with trastuzumab-deruxtecan in monkeys. Since the non-human primate model is regarded as predictive for the ILD risk in humans, this result indicates a low risk for ILD when applying M9140 to patients. The current M9140 safety data are discussed with special focus on the absence or presence of ILD with other antibody camptothecin-conjugates, for which a hypothetical pathogenic mechanism is postulated here. The favorable nonclinical profile of M9140 warrants further investigation in patients with CEACAM5-overexpressing tumors.

Endocrine-disrupting chemicals (EDCs) play an important role in the incidence of type-2 diabetes. Di-2-ethyl hexyl Phthalate (DEHP) is one of the endocrine-disrupting chemicals used as a plasticizer to impart flexibility and softness to plastic-containing materials. Mono-2-ethylhexyl Phthalate (MEHP), a DEHP's primary metabolite, is preferentially absorbed once metabolized. A previous study from our laboratory showed that DEHP and MEHP altered the key proteins such as insulin receptor (INSR) and glucose transporter-4 (GLUT4) in L6 myotubes. In a sequel to the previous study, the present study hypothesized that DEHP and its metabolite MEHP may alter the Insr and Glut4 gene expression in L6 myotubes. Therefore, to find out the molecular mechanism behind the decreased INSR and GLUT4 protein levels in the previous study, the direct effect of DEHP and its metabolite MEHP in regulating Insr and Glut4 gene transcription in L6 myotubes was studied. The L6 myotubes were exposed to 50 and 100 μM DEHP and MEHP for 24 h, followed by insulin stimulation for 20 min. We observed decreased Insr and Glut4 mRNA levels in DEHP and MEHP-treated groups. Western blot data showed decreased protein levels of MEF2A and MyoD in treated groups. ChIP assay detected a decreased association of MEF2A and MyoD to the Glut4 gene promoter and HMGA1 to the Insr gene promoter. The study revealed that DEHP and MEHP diminished the Insr and Glut4 gene expression through weakened interaction of their transcription factors on the respective promoter.

Seizures are complex electrophysiological disturbances affecting one or more populations of brain neurons. Seizures following test article (TA) exposure pose significant challenges in drug development. This paper considers the diverse neurological manifestations, mechanisms, and functional and structural assessments needed to investigate TA-related seizure liabilities, with a particular focus on nonclinical species. Accurate discrimination of seizures from convulsions (irregular involuntary body and/or limb movements) and the nuanced presentation of different seizure types (partial vs. general) and phases (prodromal, ictal, and postictal) are essential for discerning their clinical implications. In nonclinical safety testing, the most direct evaluation method to confirm existence of seizures is electroencephalography (EEG) while clinical endpoints (e.g., functional observational batteries [FOB], comprehensive neurological examinations) and neuropathological findings (e.g., neuronal necrosis in tissue sections, raised biomarker levels in cerebrospinal fluid or serum) can indicate a seizure liability and provide additional guidance to identify the origin, frequency, and severity of seizures needed to align nonclinical effects with clinical relevance. In general, the regulatory perspective is that seizures identified in nonclinical species as well as potential risk management strategies (e.g., safety margin considerations, dosing paradigms, and clinical monitoring) translate effectively for purposes of clinical risk assessment.

The presence of polystyrene plastics in the human testis has raised concerns, yet their biological activity remains poorly characterized. This study aimed to investigate the biological effects and potential regulatory genes of polystyrene nanoplastics on spermatocyte line, GC-2spd(ts). After a 24-h exposure to polystyrene nanoplastics, the results indicated cell membrane disruption, impairment of mitochondrial membrane potential, increased levels of reactive oxygen species (ROS), and induced DNA damage. Furthermore, a comprehensive transcriptomic analysis was conducted, revealing differential gene expression patterns in GC-2spd(ts) cells in response to polystyrene nanoplastics. A total of 134 differentially expressed genes (DEGs) were identified, with 48 genes upregulated and 86 genes downregulated. The Gene Ontology analysis highlighted the involvement of these genes in various spermatogenesis-related biological processes, including acrosome reaction, sperm mitochondrial organization, sperm annulus, and outer acrosomal membrane. Subsequently, the quantification of gene expression through qRT-PCR identified five key genes (NSUN7, SEPTIN4, TRIM36, EQTN, and SYT8) screened from the DEGs. In conclusion, this study provides valuable insights into the biological effects of polystyrene nanoplastics on mouse spermatocytes using comprehensive transcriptomic analysis, contributing to the establishment of a foundation for future investigations into these relevant pathways.

The Expert Panel for Cosmetic Ingredient Safety (Panel) first published the Final Report of the safety of Isobutane, Isopentane, Butane, and Propane in 1982. The Panel previously concluded that these ingredients are considered safe as cosmetic ingredients under the present conditions of concentration and use, as described in that safety assessment. Upon re-review in 2002, the Panel reaffirmed the original conclusion, as published in 2005. The Panel reviewed update frequency and concentration of use data again in 2023, in addition to newly available, relevant safety data. Considering this information, as well as the information provided in the original safety assessment and the prior re-review document, the Panel reaffirmed the 1982 conclusion for Isobutane, Isopentane, Butane, and Propane.