Toxicological Sciences最新文献

Despite the adverse effects of combustible (C-cig) and electronic cigarettes (E-cig) being well studied, their combined impact as dual product use on the blood-brain barrier (BBB) remains underexplored. This study uses both in vitro and in vivo models to examine the effect of dual use of C-cig and E-cig products on BBB integrity. For short (24 h) and prolonged (5 d) duration, brain endothelial cell (bEnd.3) and primary astrocytes were exposed to C-cig, E-cig, and three dual combinations. Assessments included cell viability, sodium fluorescein (NaF) permeability assay across monolayer, astrocyte-conditioned media, and co-culture models, western-blot analysis of tight junction (TJ) proteins (zonula occludens-1 (ZO-1), occludin, and claudin-5), and antioxidative markers (NAD(P)H quinone dehydrogenase 1 (NQO1), heme oxygenase-1 (HO-1), and superoxide dismutase 2 (SOD2)). In vivo, male mice (C57BL/6) were acutely exposed (7 d), and outcomes included changes in body weight, plasma nicotine concentration using LCMS/MS, western-blot analysis of TJ proteins, and cytokine profiles. A significant increase in the NaF permeability was observed with Dual 1 exposure (1:1 C-cig:E-cig ratio), with significant downregulation of ZO-1 after short and claudin-5 expression after prolonged exposure duration. Dual exposure groups also elevated NQO1 and HO-1 levels, indicating a shift in oxidative stress, while SOD2 levels remained unchanged. In vivo, dual use resulted in weight loss, reduced ZO-1 expression, elevated plasma nicotine concentration, and an increase in proinflammatory cytokines (IL-13, KC). Dual use of C-cig and E-cig is often misinterpreted as a safer alternative due to perceived reduction in C-cig use. Our data indicate that this might not be the case, as dual use, particularly with a 1:1 ratio, significantly alters BBB integrity.

The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor activated by environmental toxicants like halogenated and polycyclic aromatic hydrocarbons, which then binds to DNA and regulates gene expression. AHR is implicated in numerous physiological processes, including liver and immune function, cell cycle control, oncogenesis, and metabolism. Traditionally, AHR binds a consensus DNA sequence (GCGTG), the xenobiotic response element (XRE), recruits coregulators, and modulates gene expression. Yet, recent evidence suggests AHR can also regulate gene expression via a non-consensus sequence (GGGA), termed the non-consensus XRE (NC-XRE). The prevalence and functional significance of NC-XRE motifs in the genome have remained unclear. Although chromatin immunoprecipitation (ChIP) and reporter studies hinted at AHR-NC-XRE interactions, direct evidence for transcriptional regulation in a native context was lacking. In this study, we analyzed AHR binding to NC-XRE sequences genome-wide in the mouse liver, integrating ChIP-seq and RNA-seq data to identify candidate AHR target genes containing NC-XRE motifs in their regulatory regions. We found NC-XRE motifs in 82% of AHR-bound DNA, significantly enriched compared with random regions, and present in promoters and enhancers of AHR targets. Functional genomics on the Serpine1 gene revealed that deleting NC-XRE motifs reduced TCDD-induced Serpine1 upregulation, demonstrating direct regulation. These findings provide the first direct evidence for AHR-mediated regulation via NC-XRE in a natural genomic context, advancing our understanding of AHR-bound DNA and its impact on gene expression and physiological relevance.

Exposure to endocrine-disrupting chemicals (EDCs) is increasingly recognized as a risk factor for diabetes, primarily through disruption of pancreatic beta-cell function and insulin signaling. These effects can arise not only from adult exposure but also during development, as many EDCs can cross the placental barrier. However, models that accurately mimic human pancreatic islet development are limited. In this study, we reported the first toxicological application of stem cell islets (SC-islets) to investigate the developmental effect of EDCs. Using human-induced pluripotent stem cells (iPSCs), we generated SC-islets and exposed them to a mixture of bisphenol A, bisphenol S, and trans-nonachlor during differentiation. EDC exposure resulted in SC-islets with an altered transcriptional profile, characterized by reduced expression of beta-cell maturity markers, increased proliferation markers, and elevated KI67-positive cell counts. These features resembled earlier developmental stages and deviated from mature human islet profiles, suggesting a delay in differentiation. Our findings establish SC-islet differentiation as a novel and relevant in vitro model for assessing the developmental toxicity of EDCs, with outcomes consistent with in vivo studies. This model opens new avenues for mechanistic studies and chemical safety assessment in endocrine development.

Microplastics (MPs) are emerging environmental contaminants due to increasing global plastic production and waste. MPs, defined as plastic particles less than 5 mm in diameter, are formed through the degradation of larger plastics via sunlight, weathering, and microbes. These plastic compounds are widely detected in water, soil, and food, as well as human stool and blood. The gut microbiome, often referred to as our second genome, is important in human health and is the primary point of contact for orally ingested MPs. To investigate the impact of ingested MPs on the gut microbiome and the metabolome, 8-week-old male and female C57BL/6 mice were orally gavaged with mixed plastic (5 µm) exposure consisting of polystyrene, polyethylene, and the biodegradable/biocompatible plastic, poly(lactic-co-glycolic acid), twice a week for 4 weeks at 0, 2, or 4 mg/week (n = 8/group). Fecal pellets were collected for bacterial DNA extraction and metagenomic shotgun sequencing, and serum was subjected to targeted and untargeted metabolomics. A total of 1,162 bacterial species and 1,437 metabolites were evaluated for downstream analysis. MPs' exposure resulted in significant sex-specific and dose-dependent changes to the gut microbiome composition, along with substantial regulation of predicted metabolic pathways. Untargeted metabolomics in serum showed that a low MPs dose displayed a more prominent effect on key metabolic pathways, such as amino acid metabolism, sugar metabolism, and inflammation. Additionally, short-chain fatty acid (SCFA)-targeted metabolomics showed significant changes in neuroprotective SCFA levels in both sexes. Our study demonstrates that MPs dysregulate the gut microbiome and serum metabolome, highlighting potential human disease risks.

Traditional animal-based chemical safety assessments often fall short in accurately predicting human toxicities, highlighting the need for more human-relevant testing strategies. In response to this challenge, new approach methodologies have emerged, with high-throughput in vitro transcriptomic screening playing a pivotal role in elucidating mechanisms of toxicity. In this study, we developed the first human kidney in vitro toxicogenomic co-expression network using transcriptomic profiles from immortalized human renal proximal tubule epithelial cells (RPTEC/TERT1) exposed to a curated panel of nephrotoxicants. Through weighted correlation network analysis, we identified distinct gene co-expression modules and conducted comprehensive downstream analyses at the module, sample, and transcription factor levels. We integrated these insights into the human in vitro RPTEC/TERT1 TXG-MAPr, an interactive R Shiny platform designed to facilitate the interpretation of gene co-expression networks. Our findings demonstrate that module-based analysis enables the differentiation of distinct mechanisms of action. By linking transcriptional modules to KE within the nephrotoxicity adverse outcome pathway network, we reinforce the potential of gene co-expression network approaches to advance mechanism-based risk assessment and support next-generation chemical safety assessment.

Fine particulate matter (PM2.5), airborne particles with an aerodynamic diameter of ≤2.5 µm, a major air pollutant, has been implicated in sinonasal inflammatory diseases such as chronic rhinosinusitis (CRS) even at levels below national air quality standards. PM2.5 is thought to exacerbate CRS by compromising the epithelial barrier, impairing mucociliary clearance, and promoting inflammation. However, evidence linking PM2.5 exposure to sinonasal epithelial remodeling remains limited. This study investigated the effects of environmentally relevant doses of urban PM2.5 organic extract (PM2.5 OE) on primary sinonasal epithelial cell cultures derived from individuals with and without CRS. We hypothesized that PM2.5 OE exposure would induce transcriptional changes indicative of mucociliary remodeling, reduce transepithelial resistance, and increase inflammatory cytokine production. Primary nasal epithelial cells from healthy (N = 8) and CRS subjects (N = 10) were differentiated in an air-liquid interface, followed by acute (24-h) and subacute (5-day) exposure to an environmentally relevant dose of PM2.5 OE (9 μg/ml; 1.34 µg/cm2) or the vehicle control. PM2.5 OE exposure did not significantly alter these outcomes, regardless of disease status. Instead, variation was primarily driven by biological sex and CRS, with male CRS samples exhibiting downregulation of cilia assembly pathways. Cytokine production from unexposed cultures demonstrated sex-specific differences, with female-derived cultures displaying a more pro-inflammatory profile, highlighting intrinsic immune variability. These findings underscore the importance of biological sex and disease status when evaluating environmental exposures, suggesting that longer exposures may be necessary to fully capture PM2.5 OE-induced effects. This work highlights the need to investigate the crosstalk between environmental exposures and individual-specific factors influencing CRS disease progression.

In utero exposure to the synthetic estrogen diethylstilbestrol (DES) has been linked to developmental abnormalities and elevated breast cancer risk in adulthood in human and rodent models. Although the impact of DES on the mammary epithelium has been thoroughly investigated, its effect on the other cell types of the mammary gland remains understudied. Here, given that the mammary gland development is strongly associated with its microenvironment, we aimed to investigate how in utero DES exposure alters the mammary gland's stromal and immune function across key developmental stages. To achieve this aim, timed-pregnant rats were gavaged daily with DES or vehicle from gestation days 16 to 21, and female offspring mammary glands were analyzed at pre-puberty (postnatal day 21 [PND21]), puberty (PND46), and adulthood (PND90). We assessed morphological and extracellular matrix changes, performed transcriptomic cell-type enrichment analysis, measured cytokine expression, and quantified immune cell populations. DES-exposed mammary glands exhibited pronounced stromal remodeling, including increased collagen deposition and orientation by adulthood. Gene expression profiling indicated DES-induced stage-specific immune alterations: Immune cell signatures were enriched at PND21 and PND90 but diminished at PND46. Correspondingly, DES increased macrophage populations at PND21 while reducing T-lymphocyte numbers at PND46 and PND90. DES exposure also dysregulated inflammatory cytokine/chemokine expression in adult glands, suggesting a persistent inflammatory environment. In conclusion, in utero exposure to an estrogenic compound can reprogram mammary development, inducing long-term changes in the extracellular matrix and immune landscape. These disruptions to stromal-immune homeostasis may impair normal mammary morphogenesis and increase susceptibility to breast pathologies later in life.

The mycotoxin deoxynivalenol (DON) is a widespread contaminant that threatens male reproductive health, though the systemic mechanisms involving the gut-testis axis remain incompletely understood. We employed a multi-omics approach-integrating transcriptomics, 16S rRNA sequencing, and serum metabolomics-in a mouse model to investigate these mechanisms. Oral exposure to DON (2 mg/kg/day for 2 weeks) induced testicular damage and disrupted the blood-testis barrier, marked by the downregulation of Occludin and GJA1, alongside the suppression of steroidogenesis-related genes and proteins, including StAR and CYP17A1. Concurrently, DON triggered gut microbiota dysbiosis, characterized by an increased abundance of Desulfovibrio and a decline in beneficial bacteria. Serum metabolomics further identified a significant depletion of key fatty acids and the cholesterol precursor 5-Alpha-Cholestanol. Crucially, fecal microbiota transplantation from DON-treated mice reproduced testicular damage and suppressed steroidogenesis in recipient animals, directly establishing the causal role of gut microbiota in DON-induced reproductive toxicity. These findings collectively demonstrate that DON impairs male reproductive function by inducing gut microbiota dysbiosis and associated metabolic alterations. This work advances our understanding of the gut-testis axis in toxicology and provides mechanistic insights for mitigating mycotoxin-induced reproductive dysfunction.

Wildfires have surged in frequency and severity, and in 2022, they contributed to nearly 30% of the fine inhalable particulate matter (PM2.5) in the United States. Health effects from wildfire-induced wood smoke (WS) exposure include worsened pre-existing lung diseases and lung function, increased emergency room visits, and increased risk of premature death. Evidence suggests that males and females have unique responses to air pollutants, but sex-specific responses to WS remain understudied. To evaluate whether males and females differentially respond to WS, we analyzed induced sputum samples in humans following a controlled chamber exposure to WS. A total of 79 participants were exposed to 500 µg/m3 of WS for 2 h with intermittent exercise, and a subset of participants' samples were analyzed for cellularity and cytokine concentrations, and protein expression in the sputum supernatants. Cell differentials were compared between pre-, 6 h, and 24 h post-exposure, and proteomic and cytokine signatures were compared between pre- and 24 h post-exposure. A total of 368 proteins were significantly different in females, and 27 were significantly different in males post-exposure. Pathway analysis revealed inhibition of leukocyte extravasation signaling, phagosome formation, and macrophage nitric oxide and reactive oxygen species pathways in females versus males. Females had a lower percentage of iNOS+ and a higher percentage of CD301+ sputum macrophages versus males. Overall, this exploratory analysis suggests that in response to acute WS exposure, different pathways are affected in females compared with males. Future studies are needed to determine whether this confers an immune advantage and to understand the mechanisms of sex-specific WS-induced respiratory effects.