NeuroToxicology

The widespread presence of microplastics and nanoplastics has emerged as a significant environmental concern, with increasing evidence suggesting potential adverse effects on neurological health. However, the molecular mechanisms linking polystyrene exposure to Alzheimers disease (AD) remain poorly understood. In this study, an integrative systems biology framework was employed to investigate the molecular interplay between environmental polystyrene exposure and AD pathogenesis. AD-associated genes were retrieved from the Comparative Toxicogenomics Database (CTD) and DisGeNET, while polystyrene-responsive genes were obtained from CTD. Integration of these datasets identified 16 shared genes potentially connecting polystyrene exposure with AD. Transcriptomic analysis of the hippocampal dataset GSE29378 revealed significant differential expression of several overlapping genes between AD and healthy controls. Functional enrichment analyses demonstrated that these genes are predominantly involved in oxidative stress, inflammatory signaling, apoptosis, and synaptic function, all of which are central to AD pathology. Weighted gene co-expression network analysis (WGCNA) further identified disease-associated modules containing multiple intersecting genes strongly correlated with AD clinical traits. Protein-protein interaction analysis highlighted IL1B, CASP3, BCL2, ACHE, and APOE as key hub genes, indicating their potential roles in integrating environmental stress responses with neurodegenerative pathways. Independent validation using the GSE48350 dataset confirmed the robust diagnostic performance of several hub genes in discriminating AD from control samples. Collectively, these findings suggest that environmental polystyrene exposure may promote AD progression through neuroinflammation, oxidative stress, apoptosis, and synaptic dysfunction, providing novel mechanistic insights and identifying promising molecular targets for future experimental, clinical, and epidemiological investigations.

Environmental factors including chemical exposures are important contributors to Parkinsons disease (PD). Nearly all well-validated chemicals involved in PD affect mitochondria, and the great majority of those identified inhibit mitochondrial complex I, causing ATP depletion and oxidative stress. We hypothesized that inhibition of mitochondrial complex III would also cause dopaminergic neurotoxicity. Using Caenorhabditis elegans to evaluate the in vivo effects of complex III-inhibiting pesticides antimycin A and pyraclostrobin, we found that both caused selective dopaminergic neurotoxicity. We evaluated exacerbation of dopaminergic neurotoxicity by the presence of -synuclein, and pdr-1/PRKN and pink-1/PINK1 mutant backgrounds and found increased neurotoxicity for pdr-1. Complex III inhibition caused a more-oxidized cellular environment in those neurons and pharmacological and genetic antioxidant interventions rescued neurotoxicity, but energetic rescue attempts did not. Finally, optogenetic production of superoxide anion specifically at complex III caused dopaminergic neuronal damage. Thus, redox stress at complex III following chemical exposure causes dopaminergic neurotoxicity in vivo in C. elegans.

Benzyl paraben (BzP) and butyl paraben (BuP) are used as preservatives and antimicrobial agents in cosmetics, pharmaceuticals, and foods. BzP and BuP have been detected in urine, placental tissue, and ovarian follicular fluid and are understudied with regards to their endocrine activity, raising concerns on their impact to the reproductive system. We tested the hypothesis that BzP and BuP are toxic to the ovary and behave similarly to other structurally similar endocrine disrupting chemicals, such as phthalates and terephthalates, by altering hormone levels and impacting cell growth and gene expression in vitro. Untreated mouse antral follicles were exposed to vehicle, 0.1, 1, 10, or 100 g/mL BzP, BuP, or the BuP analog monobutyl terephthalate (MBuTP) for 96 hours. The highest dose of BzP and BuP were cytotoxic to follicles, suggesting that medium chain length hydroxybenzoates are more cytotoxic to the ovary than corresponding terephthalic acids. BzP significantly increased levels of estradiol and testosterone compared to control. BuP decreased follicle growth and disrupted expression of cell cycle regulators, similar to phthalates. The peroxisome proliferator-activated receptor gamma (PPARg)-transcriptionally controlled gene Fabp4 was significantly upregulated by both BzP and BuP, whereas MBuTP upregulated all four PPAR target genes and decreased follicle growth. Overall, BzP, BuP, and MBuTP disrupted hormone levels, follicle growth, and cell cycle progression, suggesting similarities in toxicity to phthalates and potential endocrine disruption. Further study should be done on the reproductive toxicity and endocrine disrupting effects of chemicals similar in structure to phthalates to reduce exposure to endocrine disruptors and inform design of safer replacements.

Bio-based plastics, such as polylactic acid, offer an alternative to petroleum-based plastics and a prospect to address the plastic pollution problem. While mounting evidence suggests that microplastics pose a human health threat, the risk posed by bio-based plastics remains unknown. Here, we use Caenorhabditis elegans to investigate the effects of secondary microplastics from 3D-printed polylactic acid on fertility and lifespan. We have created and characterized microplastics from a 3D-printed item using cryogenic milling. Using these microplastics, we exposed C. elegans and assessed lifespan, reproduction, and various stress responses. Our studies demonstrate that exposure to 1 {micro}g/L polylactic acid microplastics reduces fertility and alters the gonad structure. When examining germline integrity, we find chromosomal disorganization in the gonad after polylactic acid microplastic exposure and increased apoptotic cell death, which correlates with a DAF-16/FOXO and gst-4 oxidative stress responses. While lifespan has been observed to decrease with exposure to microplastics of different polymer types, we did not observe a change in lifespan with exposure to polylactic acid microplastics. The germline is likely more sensitive than somatic tissues under our exposure conditions. The reduction in fertility is driven by alterations to the germline, characterized by chromosome aberrations, oxidative stress, and cell death.

BackgroundPer- and polyfluoroalkyl substances (PFAS) are ubiquitous environmental pollutants that are posited to be neurotoxic to the developing brain; however, the impact of prenatal exposure to PFAS -- particularly to newer, short-chain PFAS -- on brain development across childhood is unclear. MethodsConcentrations of 9 PFAS were quantified in cord blood plasma of 459 infants who later participated in structural and diffusion magnetic resonance imaging (MRI) at ages 4.5, 6, 7.5, and 10.5 years, providing estimates of regional cortical thickness and surface area, subcortical volumes, and fractional anisotropy (FA) of key white matter tracts. Longitudinal mixed effect models estimated associations of PFAS with age 4.5 brain metrics and their developmental trajectories across childhood. ResultsHigher concentrations of long-chain PFAS (PFNA, PFHxS, PFDA) in cord blood were associated with lower surface area of the right paracentral lobule at age 4.5. PFHpA was associated with faster surface area growth in the left rostral anterior cingulate and slower growth in the right caudal middle frontal gyrus from 4.5 to 10.5 years. The short-chain compound PFBS was linked with greater FA in 17 of 27 white matter tracts at 4.5 years; those associations attenuated with age. Finally, PFOA was associated with lower FA in 6 tracts at 4.5 years. ConclusionsPrenatal exposure to PFAS was associated with altered development of frontal and paracentral regions and of white matter microstructure. These findings highlight the need for further research examining the long-term effects of prenatal exposure to PFAS on childrens neurodevelopment.

Pesticide use is ubiquitous. While pesticide resistance in target species such as insects is a well-known phenomenon, it is less known how pesticide exposures affect the genetics of non-target species. Here, we demonstrate the research value of integrating existing datasets to study the relationship between chemicals and biodiversity from the genetics perspective by analyzing spatial pesticide concentration data and genetic data from Europe that were not initially generated for toxicological purposes. Specifically, we found associations between environmental pesticide concentrations and genetic variation (i.e., single nucleotide polymorphisms, SNPs) in a non-target species, the wild boar. Gene Ontology (GO) terms and biological signaling pathways related to nervous system function were overrepresented for the impacted genes, especially for insecticides and fungicides. Further, we found that external studies characterizing the molecular mechanisms of these pesticides revealed the same pesticide - GO relationships as those observed in our analysis. Our results show that pesticide-induced genetic changes may not be constrained to target species but may also have an impact on the long-term viability of other wildlife populations. We therefore encourage further research into this area and collaboration across disciplines to develop more comprehensive designated datasets for such analyses. This finding also urges the consideration and inclusion of chemical exposure into conservation protection strategies and greater consideration of genetic impacts from chemicals in environmental risk assessment.

Tetrabromobisphenol A (TBBPA), is one the most widely produced brominated flame retardant, detected in human matrices including cord plasma, raising concern over its impact on embryonic development. Our previous work demonstrated that TBBPA disrupts craniofacial cartilage development in zebrafish; however, inhibition of bone morphogenetic protein (BMP) signaling did not rescue these defects, suggesting the involvement of alternative molecular mechanisms. Transcriptomic profiling revealed significant upregulation of aryl hydrocarbon receptor (Ahr) signaling genes, including cyp1a and cyp1c, as well as reactive oxygen species (ROS) responsive genes, such as nfe and gstp. Consistent with these findings, KEGG pathway enrichment analysis identified significant enrichment of pathways involved in xenobiotic metabolism, cytochrome P450-mediated metabolism, and molecular docking predicted stronger binding of TBBPA to Ahr2 than the Ahr2 agonist TCDD. Then we investigated the role of Ahr signaling and ROS in TBBPA-induced craniofacial cartilage defects using microinjection of Ahr2 translation-blocking morpholino and the antioxidant N-acetylcysteine (NAC), respectively. Immunohistochemistry confirmed concentration-dependent induction of Cyp1a and ROS at environmentally relevant concentrations (0.05;0.005 uM). Ahr2 knockdown using a translation-blocking morpholino rescued TBBPA-induced alterations in Cyp1a expression, ROS levels, DNA damage, the expression of chondrogenesis-related markers (Sox10 and Sox2), and epithelial to mesenchymal transition (EMT) markers (E-cadherin, N-cadherin, and Snail2). Furthermore, Ahr2 knockdown rescued several TBBPA-induced alterations in craniofacial cartilage parameters. Co-exposure of TBBPA with the antioxidant NAC rescued the ROS and DNA damage and rescued only ceratohyal cartilage length, whereas other cartilage parameters remained disrupted. These findings establish a causal role for the Ahr-Cyp1a axis in TBBPA-induced craniofacial cartilage developmental toxicity and identify ROS as an important downstream contributor, indicating that both ROS-dependent and ROS-independent Ahr mechanisms underlined the observed TBBPA induced craniofacial defects.

Typical environmental exposures to the toxic class of chemicals known as polycyclic aromatic hydrocarbons (PAHs) involve complex mixtures; however, relatively few mechanistic toxicity studies have evaluated them as environmental mixtures, instead focusing on individual compounds or simple mixtures. In this study, we first derived Republic Sediment Extract (REPSE), a complex PAH mixture extracted from sediment at the Republic Creosoting site of the Elizabeth River in Norfolk, Virginia. After characterizing the PAH contents of REPSE, we evaluated its mechanisms of developmental neurotoxicity in three evolutionarily distinct taxa, leveraging the unique strengths of Atlantic killifish, zebrafish, and Caenorhabditis elegans as model species, with a focus on the Aryl hydrocarbon Receptor (AhR) pathway. Embryonic REPSE exposure caused induction of CYP1A in both fish species at sub-teratogenic concentrations, consistent with activation of the canonical AhR pathway. These sub-teratogenic exposures nevertheless induced neurotoxicity across both fish species, altering neurobehavioral phenotypes in fish, and induced dopaminergic neuronal damage in worms, again at non-teratogenic concentrations. To determine whether these effects were linked to canonical AhR response pathways, we examined killifish offspring from the pollution-adapted Republic Creosoting population, which exhibited characteristic recalcitrance to CYP1A induction, but remained susceptible to the neurobehavioral effects of REPSE. The induction of neuronal damage in worms provides orthogonal evidence for a non-AhR mechanism, because C. elegans AhR is not transcriptionally activated by PAHs as in vertebrates. Further probing of potential mechanisms underlying REPSE-induced neurotoxicity in worms revealed altered neuronal redox status (roGFP) and energy availability (ATP:ADP ratio). Collectively, our multispecies approach reveals conserved mechanisms of PAH mixture neurotoxicity, including effects that extend beyond canonical AhR signaling.

BACKGROUND: Pesticides are extensively used in agriculture, raising concerns about their potential impact on human health through dietary and environmental exposure. OBJECTIVES: This study evaluated the in vitro cytotoxicity of ten commonly used pesticides and their mixtures (lambda-cyhalothrin, cypermethrin, deltamethrin, tebuconazole, glyphosate, acetamiprid, cyprodinil, piperonyl butoxide, fluopyram, and imazalil) on human intestinal Caco-2 cells. METHODS: Cytotoxicity was assessed using the MTT assay, as a measure of metabolic activity, and the trypan blue exclusion test, as an indicator of cell membrane integrity. FINDINGS: Results showed that high concentrations (100 mg/L) of all pesticides significantly reduced cell viability and vitality. Notably, glyphosate and tebuconazole exhibited significant toxicity even at lower concentrations, respectively 0.1 mg/L and 10 mg/L. Combination treatments (Top 3 and Top 8 pesticide mixtures) retained the cytotoxic effects observed for individual compounds, showing additive (non-synergistic) effects. CONCLUSIONS: Overall, these findings indicate that certain pesticides-based herbicides can exert cytotoxic effects on intestinal cells even at relatively low concentrations and highlight the importance of using the component-based approach in mixture risk assessment for humans. This study was performed as part of the EU SPRINT (Sustainable Plant Protection Transition: A Global Health Approach) project.

Abstract Background. Acrylamide, a neurotoxicant in heated foods and smoke, is linked to occupational neuropathy, but evidence regarding chronic, low-level population exposure remains limited. We evaluated the association between acrylamide exposure biomarkers and peripheral neuropathy among U.S. adults. Methods. A total of 2,266 NHANES 2003-2004 participants (age >40) were analyzed. Exposure was assessed via hemoglobin adducts (HbAA/HbGA); neuropathy via monofilament testing >1 site). Survey-weighted logistic regression models adjusted for confounders. Sensitivity analyses included cubic splines, diabetes stratification, and multiple imputation. Results. Neuropathy prevalence was 15.5%. In adjusted models, neither adduct was associated with neuropathy (HbAA OR: 0.98, 95% CI: 0.82-1.17; HbGA OR: 0.91, 95% CI: 0.77-1.08). No dose-response gradient was observed. Expected risk factors (age, diabetes) showed strong associations, validating model sensitivity. The null result remained robust across sensitivity analyses, including a stricter outcome definition and multiple imputation (pooled OR: 0.97, 95% CI: 0.83-1.14). Conclusions. Acrylamide adducts were not associated with peripheral neuropathy in this national sample. General population levels (~55-70 pmol/g) lie well below established occupational no-observed-adverse-effect levels (~510 pmol/g) and clinical neuropathy thresholds (~6,000 pmol/g), providing a mechanistically coherent explanation for this null result.

Transactive response DNA-binding protein 43 (TDP-43) aggregation and loss of function are hallmark features of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) among other neurodegenerative diseases. Despite epidemiological evidence linking environmental exposures to neurodegeneration, few toxicants have been directly associated with neurodegeneration. Here, we performed a high-content imaging screen, using a library of over a thousand chemical compounds that are considered high risk for human exposure and identified 21 toxicants that drive TDP-43 aggregation. Among the top chemical hits, five belonged to the dithiocarbamate (DTC) class of thiol-reactive compounds including the agricultural pesticides thiram and ziram. Thiram directly promoted TDP-43 cysteine oxidation and intermolecular crosslinking, whereas ziram induced TDP-43 aggregation via zinc imbalance and enhanced oxidative stress, suggesting DTCs disrupt redox homeostasis. In primary neurons and human iPSC-derived neurons, DTCs led to TDP-43 aggregation and prominent splicing defects consistent with loss of TDP-43 function. In exposed zebrafish, DTCs impaired TDP-43 function and triggered widespread transcriptional changes reflected by perturbed stress response and metabolic signatures. By combining TDP-43 loss of function mutations with chemical exposures, we observed accelerated TDP-43 loss of function and chemical-induced aggregation, supporting a multiple hit mechanism driving TDP-43 dysfunction. Together, these findings identify DTCs, particularly those used as agricultural pesticides, as dominant modifiers of TDP-43 proteostasis and identify redox imbalance and zinc homeostasis as a central molecular mechanism linking toxicant exposure to TDP-43 proteinopathy.

Lead (Pb) exposure is strongly associated with cardiovascular diseases, but the effects of developmental Pb exposure on the electrophysiological properties of human cardiomyocytes have not yet been investigated. Using human induced pluripotent stem cell (iPSC)-derived cardiomyocytes, we investigated the effects of human-relevant Pb exposure during ventricular cardiomyocyte differentiation on action potential properties and calcium dynamics in differentiated myocytes. We exposed 2 iPSC lines, from 1 male and 1 female donor, to Pb (0.5 or 5 micromolar) or control during only the first 8 days of differentiation, prior to functional maturation. Differentiation was carried out using an established protocol involving temporal modulation of Wnt signaling, followed by purification and maturation of contractile myocytes. We measured action potential properties and calcium dynamics using fluorescent dyes and optical mapping. We hypothesized that Pb exposure would adversely affect cardiomyocyte function, with effects persisting after cessation of exposure. In keeping with this hypothesis, we found significant Pb-induced changes in calcium (Ca) transients and action potential dynamics that were concentration and cell line specific and persisted well after exposure had ended. In the female cell line, beat frequency significantly increased with Pb exposure for both action potentials and Ca transients, while in the male cell line, beat frequency significantly decreased with Pb exposure for action potentials and increased for Ca transients. For voltage measurements, we observed significantly increased arrythmias with Pb exposure in both cell lines. Significant changes in repolarization and recovery time (for voltage and Ca, respectively) were present with Pb exposure in both cell lines. Gene expression of Ca transporters/channels and K channels were not affected, suggesting that persistent effects of Pb exposure on cardiomyocyte electrophysiology may occur through post-translational mechanisms. Overall, this study paves the way for future work to examine how exposure to Pb impacts long-term cardiac function through developmental programming.

Early life adversity (ELA) and ambient fine particulate matter (PM2.5) are hypothesized to be environmental risk factors for altered brain structure and psychopathology, but their unique and interactive effects in childhood remain unclear. This study examines the interactive associations of ELA and annual average residential PM2.5 exposure (total mass and 15 components) on total amygdala and basolateral amygdala subregion volumes and psychopathology symptoms in a subset of children (N=3,601, 45% assigned female at birth, 9-10 years) from the Adolescent Brain Cognitive Development Study. Linear mixed-effects models, adjusting for sociodemographic factors, co-pollutants, and neuroimaging covariates, showed that ELA was associated with greater bifactor model-defined general, specific internalizing, and specific externalizing symptoms of psychopathology. PM2.5 moderated ELA associations with specific externalizing symptoms, with greater symptoms in those exposed to higher ELA and higher PM2.5 exposures. Among youth with higher ELA, smaller basolateral paralaminar volumes were linked to greater general and specific externalizing symptoms. These findings underscore the importance of considering psychosocial and physical environmental co-exposures when identifying children at risk for psychopathology.

Current insecticide toxicology still lacks an integrated understanding of how lethal and sublethal exposure shape organismal performance across biologically and environmentally relevant contexts. In particular, insecticide susceptibility may vary with physiological state, environmental conditions, and recent exposure history, factors that are only partially captured by standardized toxicity assessments. Here, using Drosophila melanogaster, we systematically compared responses to three insecticides with distinct modes of action - acetamiprid, chlorantraniliprole, and deltamethrin - across developmental stages, sexes, adult ages, and ambient temperatures. Insecticide sensitivity varied substantially across these conditions, with temperature modulating toxicity in a compound-dependent manner. Notably, deltamethrin caused substantial lethality at concentrations more than 10,000-fold below approved field application rates. Beyond these context-dependent differences in acute toxicity, sublethal pre-exposure to each insecticide rapidly reduced lethality during a subsequent challenge with the same compound, with increased tolerance already detectable after 24 h. Importantly, these exposure conditions that enhanced insecticide tolerance were associated with reduced resistance to environmental challenges, including heat and nutrient starvation, revealing a potential trade-off in organismal stress resilience. Acetamiprid exposure further altered reproductive performance in a concentration-dependent manner, with higher exposure reducing egg production while increasing developmental success among the resulting offspring, such that the number of offspring reaching adulthood remained largely unchanged. Together, these findings demonstrate that insecticide susceptibility is highly context dependent and can be rapidly modified by recent exposure history. We identify short-term, compound-specific, and potentially costly tolerance as an underappreciated consequence of insecticide exposure and highlight the importance of incorporating biological context, environmental conditions, and sublethal exposure history into pesticide risk assessment.

2,4-Dinitrochlorobenzene (DNCB) is a well-characterized skin sensitizer that has been widely used in immunological and toxicological research and, historically, in clinical immunotherapy. Although it is a well-investigated chemical, this is the first study focusing on the dose response behavior at low-level concentrations. The aim was to reveal potential hormetic effects due to its known Nrf2 inducting activity. Therefore, THP-1 cells were treated with low doses of DNCB and two endpoints were evaluated for hormetic responses: metabolic activity using a resazurin-based assay and immune activation by measuring CD86 and CD54 expression using flow cytometry. The results showed a significant hormetic effect on the metabolic endpoint at the lower cell density for both analyzed time points, and a hormetic tendency at the higher cell density. Metabolic activity increased to approximately 125% of the control at 0.05 micromolar DNCB. For the immunological endpoint a slight decrease in CD86 and CD54 surface marker expression was observed, up to -16% and up to -12% compared to control at 0.5 micromolar DNCB. These findings highlight the importance of including low dose concentrations when characterizing chemical dose-response relationships and evaluating toxicological risk.

Environmental microplastics and nanoplastics (MNPs) are emerging contaminants that accumulate in human tissues, including the brain, yet their mechanistic impact on the nervous system remains poorly understood. Converging postmortem evidence indicates increased MNP burden in brains from individuals with dementia, suggesting a potential link between plastic accumulation and disorders of the nervous system. However, whether MNPs directly contribute to brain aging and ensuing neurodegenerative processes, or disrupt neurodevelopment, is unknown. Here, we show that exposure to environmentally relevant MNPs induces cellular senescence and innate immune transcriptional programs in human brain organoids. Using region-specific cortical organoids, we demonstrate that synthetic polystyrene (PS), polyethylene terephthalate (PET), low-density polyethylene (LDPE), and high-density polyethylene (HDPE), as well as environmental ocean-derived MNPs (eMNPs) isolated from the coast of Hawaii, elicit a robust neuroinflammatory response. Transcriptomic analyses revealed activation of senescence-associated secretory phenotype (SASP) pathways. MNP exposure further disrupted neurodevelopmental trajectories, impairing neuroectodermal differentiation and redirecting lineage commitment toward mesoderm-like states, with concomitant enrichment of choroid plexus-like populations and a marked imbalance in neuronal and glial differentiation. These developmental alterations occurred in parallel with a pro-inflammatory and senescent microenvironment, suggesting coordinated disruption of developmental and aging programs. Importantly, high-density multielectrode array recordings revealed that MNP exposure altered electrophysiological activity and neuronal network dynamics, demonstrating that MNP-driven perturbations translate into dysfunctional neurological outcomes. Collectively, our findings identify MNPs as potent disruptors of human neurophysiology, linking plastic exposure to altered developmental trajectories, cellular senescence, neuroinflammation, and impaired neuronal network activity, providing mechanistic insights into how plastic accumulation may contribute to impaired brain dynamics.

Large-scale chemical screens are important tools for hazard identification and chemical prioritization, but they less commonly progress from identifying a phenotype to identifying its mechanism. Here, we used zebrafish embryos to screen 4,657 chemicals from the U.S. EPA ToxCast Phase III library for disruption of embryonic development and advanced selected hits through sequential validation using original library stocks, independently sourced chemicals, concentration-response analysis, transcriptomics, and functional experiments. Of 61 primary hits subjected to repeat testing, 33 reproduced the original phenotype, and four of eight compounds subsequently tested using independently sourced chemicals exhibited reproducible concentration-dependent developmental toxicity. We then investigated purpurin, an understudied anthraquinone pigment that caused pericardial edema, circulation defects, and body-axis abnormalities. Transcriptomic analysis of purpurin-exposed embryos revealed coordinated suppression of pathways involved in calcium regulation, ion transport, and neuronal signaling. Increasing extracellular calcium produced a concentration-dependent rescue of purpurin-induced developmental abnormalities, whereas equivalent magnesium supplementation did not, supporting a role for calcium availability or homeostasis in purpurin developmental toxicity. These results demonstrate that large-scale in vivo toxicity screening can be integrated with independent chemical validation and functional follow-up to move beyond hazard identification toward mechanistic understanding of how environmental chemicals disrupt embryonic development.

Several studies have been conducted on human exposure to ultrafine particulate matter (UFPM), Black carbon (BC), and polystyrene nanoplastics (PS-NPs). However, it remains unclear whether different chemical types of environmental nanoparticles induce a similar mitochondrial stress response or a unique particle-specific response. In the present study, we examined the molecular mechanisms underlying nanoparticle-induced mitochondrial stress response and immunotoxicity using human peripheral blood mononuclear cells exposed to UFPM, BC, and PS-NPs under similar experimental conditions. Oxidative stress, mitochondrial adaptation, respiratory chain integrity, mitochondrial integrated stress response, inflammatory signaling, and systems-level interactions between molecules were analyzed through the evaluation of the expression of NRF2, HIF-1, PGC-1, TFAM, OMA1, DELE1, mitochondrial ND1, Complex I-V, NF-{kappa}B, TNF-, and NLRP3 and the use of principal component analysis, hierarchical clustering, and correlation networks. All three nanoparticles caused oxidative stress and mitochondrial dysfunction with different kinetics and mechanisms. UFPM mostly induced an acute antioxidant response and mitochondrial adaptation; BC led to chronic mitochondrial dysfunction, chronic activation of the OMA1-DELE1-mediated mitochondrial ISR pathway, and inflammation; while PS-NPs induced low but chronic mitochondrial adaptation along with mitochondrial biogenesis and stress responses. Our systems-level analysis showed that oxidative stress, mitochondrial adaptation, mitochondrial ISR, and inflammation represent a highly connected molecular network regardless of the physicochemical nature of the nanoparticles, with the OMA1- DELE1 axis being a key regulatory node connecting mitochondrial stress response and inflammation. Overall, we have found that mitochondrial stress response is a common mechanism underlying the toxicity of chemically different nanoparticles and have also revealed particle-specific stress-response dynamics responsible for the degree and persistence of cellular damage. The current work presents novel insights into the molecular mechanisms of nanoparticle-induced immunotoxicity and suggests OMA1, DELE1, NRF2, PGC-1, TFAM, ND1, and Complex I-V as potential biomarkers.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants associated with adverse female reproductive outcomes. However, most prior studies examined individual PFAS, despite that humans are exposed to complex PFAS mixtures. Here, we investigated the ovarian effects of a mixture of five commonly detected long-chain PFAS, including PFOS, PFOA, PFNA, PFDA, and PFHxS, using complementary in vivo mouse and in vitro 3D ovarian follicle culture models. Young adult female mice were exposed to a range of concentrations of the PFAS mixture (PFASmix) through daily drinking water for 8 weeks. PFASmix at high concentrations (PFASmix-high) disrupted mouse estrous cyclicity, decreased circulating estradiol, increased testosterone, and promoted follicular atresia. Antral follicles from exposed mice showed decreased Lhcgr and increased Amh expression. Although the number of ovulated oocytes was unchanged following superovulation, PFASmix-high reduced oocyte size and polar body extrusion and altered oocyte cytoskeletal characteristics. In the 3D follicle culture model, direct PFASmix exposure impaired follicle growth, ovulation, and oocyte maturation in a concentration-dependent manner. PFASmix-high suppressed the periovulatory expression of Areg, Ereg, Tnfaip6, and Adamts1 and impaired corpus luteal (CL) development and function, as evidenced by reduced CL spheroid growth and cell survival, decreased expression of Star, Cyp11a1, Hsd3b1, and Lhcgr, and reduced progesterone secretion. PFASmix-high exposure additionally altered the expression of multiple PPAR{gamma}-associated genes in cultured ovarian follicles. Benchmark dose modeling identified estrous cyclicity and follicle rupture as sensitive in vivo and in vitro endpoints, respectively. Together, these findings demonstrated that exposure to the mixture of long-chain PFAS disrupts multiple stages of ovarian function, from follicular development, oocyte maturation to ovulation and luteal development and function and provided mechanistic and quantitative evidence for the reproductive toxicity of PFAS mixtures.

Environmental exposure involves pollutant mixtures. Building on evidence that individual bisphenols alter zebrafish larval physiology and transcriptomic profiles at ng/L concentrations, we assessed the effects of specific mixtures of BPS, BPF, and BPAF without (M1) or with (M2) BPA. Experimentally, M1 and M2 induced 4.16% and 6.54% mortality in zebrafish larvae, despite the concentration addition model predicting no toxicity. Both mixtures reduced swimming-locomotor activities. These behaviors were accompanied by organ-level functional defects, as in vivo optical mapping revealed bradycardia and increased high-frequency (30-80 Hz) brain oscillations for both mixtures, while M2 additionally altered low-frequency (0.2-4 Hz) brain activity. The neurophysiological changes were accompanied by neurovascular remodeling, with in vivo two-photon microscopy revealing decreased vascular length and branching. Finally, transcriptomic analysis revealed common M1- and M2-induced alterations linked to pathways of vascular function, neuronal communication, and metabolism. M2 altered additional pathways of cardiac and neuronal signaling, consistent with the reported organ-physiology effects. We discuss the environmental relevance of mixture exposures and assess whether BPA intensifies mixture-induced responses.