Assessing the human health risks of perfluorooctane sulfonate by in vivo and in vitro studies

Insights into Toxicological Mechanisms of Per-/polyfluoroalkyl Substances by Using Omics-centered Approaches

The extensive presence of per-/polyfluoroalkyl substances (PFASs) in the environment and their adverse effects on organisms have garnered increasing concern. With the shift of industrial development from legacy to emerging PFASs, expanding the understanding of molecular responses to legacy and emerging PFASs is essential to accurately assess their risks to organisms. Compared with traditional toxicological approaches, omics technologies including transcriptomics, proteomics, metabolomics/lipidomics, and microbiomics allow comprehensive analysis of the molecular changes that occur in organisms after PFAS exposure. This paper comprehensively reviews the insights of omics approaches, especially the multi-omics approach, on the toxic mechanisms of both legacy and emerging PFASs in recent five years, focusing on hepatotoxicity, developmental toxicity, immunotoxicity, reproductive toxicity, neurotoxicity, and the endocrine-disrupting effect. PFASs exert various toxic effects via lipid and amino acid metabolism disruption, perturbations in several cell signal pathways, and binding to nuclear receptors. Notably, integrating multi-omics offers a thorough insight into the mechanisms of toxicity associated with PFASs. The gut microbiota plays an essential regulatory role in the toxic mechanisms of PFAS-induced hepatotoxicity. Finally, further research directions for PFAS toxicology based on omics technologies are prospected.

Perfluorodecanoic acid (PFDA) increases oxidative stress through inhibition of mitochondrial β-oxidation

PER: and polyfluoroalkyl substances (PFAS) are a large group of synthetic organic chemicals that are ubiquitous environmental pollutants. Among PFAS, perfluorodecanoic acid (PFDA) is one of the most toxic compounds, but the molecular basis behind its toxicity is not fully understood. In an interspecies comparison with placental cells (HTR-8/SVneo) and zebrafish embryos, we demonstrate that PFDA induces mitochondrial dysfunction and impairs fatty acid β-oxidation. Reduced β-oxidation leads to less TCA cycle activity, resulting in less NADH and consequently NADPH production. Thereby NADPH-dependent glutathione recycling is impaired, increasing cellular oxidative stress that can only be partially compensated by NRF2 activation.

Perfluorooctanesulfonic acid (PFOS) removal from aqueous solution through N-doped porous copper-carbon composite derived from recycled copper obtained from fly ash incinerator: Water decontamination via municipal waste remnants

Invincible growth in waste production is the consequence of overpopulation, which should be addressed to reduce the occupied landfill surface needed for their disposal and to alleviate the leachate of extremely hazardous material into the soil and water bodies. In this study, copper (Cu) was extracted from fly ash of a municipal solid waste incinerator by an electro-chemical method, which was optimized to recover the highest amount of Cu, and then it was chelated with 4-aminobenzoic acid (AM) and terephthalic acid (TM) in an aqueous phase. The obtained composites were then heated to form a porous calcinated copper-carbon composite and utilized to adsorb the forever contaminant of PFOS from aqueous solutions. As the calcinated composite of Cu/AM with a ratio of 1:1 removed a greater amount of PFOS from the aqueous solution than Cu/TA, it was utilized as the ultimate adsorbent. The platform adsorbent was subjected to multiple characterizations, including XRD, FESEM, elemental mapping, TEM, BET, EDS, ICP-OES, FTIR, DLS, and point of zero charges, as well as optimization of several operational parameters involving pH, adsorbent dosage, initial PFOS concentration, and contact time. At the neutral pH, under the optimal conditions (adsorbent dosage of 1 g L-1 and 5 h), 97.23% of PFOS was eliminated from the solution spiked with 5 mg L-1 of PFOS. The equilibrium data were best fitted with Frundlich isotherm, and the maximum adsorption capacity of 402 mg g-1 was achieved. The optimal conditions were also applied to PFOA, demonstrating high adsorption of different types of PFAS. The recovery tests of the adsorbent conducted 5 times on the solution spiked with 10 mg L-1 of PFOS showed a slight decrease in PFOS removal at least for 5 regeneration cycles, demonstrating the high adsorption capacity and its reusability, thereby validating its feasibility for large-scale applications.

Neurotoxicity of per- and polyfluoroalkyl substances: Evidence and future directions

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in various products, including food packaging, textiles, and firefighting foam, owing to their unique properties such as amphiphilicity and strong CF bonds. Despite their widespread use, concerns have arisen due to their resistance to degradation and propensity for bioaccumulation in both environmental and human systems. Emerging evidence suggests a potential link between PFAS exposure and neurotoxic effects, spanning cognitive deficits, neurodevelopmental disorders, and neurodegenerative diseases. This review comprehensively synthesizes current knowledge on PFAS neurotoxicity, drawing insights from epidemiological studies, animal experiments, and mechanistic investigations. PFAS, known for their lipophilic nature, tend to accumulate in lipid-rich tissues, including the brain, breaching biological barriers such as the blood-brain barrier (BBB). The accumulation of PFAS within the central nervous system (CNS) has been implicated in a spectrum of neurological maladies. Neurotoxicity induced by PFAS manifests through a multitude of direct and indirect mechanisms. A growing body of research associated PFAS exposure with BBB disruption, calcium dysregulation, neurotransmitter alterations, neuroinflammation, oxidative stress, and mitochondrial dysfunction, all contributing to neuronal impairment. Despite notable strides in research, significant lacunae persist, necessitating further exploration to elucidate the full spectrum of PFAS-mediated neurotoxicity. Prospective research endeavors should prioritize developing biomarkers, delineating sensitive exposure windows, and exploring mitigation strategies aimed at safeguarding neurological integrity within populations vulnerable to PFAS exposure.

Responses and mechanisms of perfluoroalkyl acid release to the cumulative effects of propeller jet force over time

As the discharge of exogenous perfluoroalkyl acids (PFAAs) is gradually controlled, the secondary release of endogenous PFAAs is poised to become a major challenge. However, the effects of complex hydrodynamic conditions, such as disturbance from ship propeller jets, on PFAA release, are still poorly understood. In the present study, a propeller jet disturbance simulation experiment was carried out using an indoor flume to investigate the responses and mechanisms of PFAA release to the cumulative effects of jet force over time. Although an increase in jet action time (t) increased the total amount of dissolved PFAAs in the overlying water, PFAA dissolution intensity decreased. Conversely, increase in t induced a rise in both total PFAA amount adsorbed and adsorption intensity in suspended particulate matter (SPM). Moreover, differences in functional groups and carbon-fluorine chain lengths resulted in different types of PFAAs exhibiting different sensitivities to changes in t during dissolution and adsorption. During the jet disturbance, there were distinct shear zoning and pressure gradients in the flow field, contributing to the tendency of PFAAs to be distributed in the overlying water. However, after the disturbance, PFAAs tended to distribute in the SPM. Changes in t consistently affected the partition behavior of long-chain PFAAs (C ≥ 7), whereas the effect on the partition behavior of short-chain PFAAs (C < 7) was rather short-lived. In contrast, Perfluoroalkyl carboxylic acids were more readily released from the sediments and porewater than Perfluoroalkyl sulfonic acids; however, the difference decreased with increasing t. Both shear impulse and squeeze impulse showed a significant linear positive correlation with PFAA release (p < 0.05), but the effect of shear impulse was greater. The findings provide perspectives for further understanding of PFAA release under jet disturbance and could facilitate endogenous PFAA contamination control.

Role of Rab proteins in PFOA-induced changes in boar sperm motility and capacitation

Perfluorooctanoic acid (PFOA), a pervasive environmental contaminant, elicits adverse effects on sperm functions, including sperm motility and capacitation status. However, the specific mechanisms by which PFOA disrupts sperm functions during capacitation remain poorly elucidated. Therefore, this study aimed to investigate the molecular mechanisms underlying the PFOA-induced inhibition of sperm motility and capacitation in boar spermatozoa by focusing on Ras-related (Rab) proteins, which regulate membrane trafficking and play key roles in male sperm development, acrosome formation, and the acrosome reaction. Results showed significant reductions in sperm motility and various kinematic parameters following PFOA exposure. Correlation analysis revealed that Rab14 was positively correlated with dance mean (DNM) and negatively correlated with wobble (WOB), indicating that PFOA might affect sperm motility through Rab14 and potentially lead to reduced pregnancy rates. Differences in Rab25 were positively correlated with differences in total motility (MOT), progressive motility (PRG), linearity (LIN), and mean angular displacement (MAD), suggesting that PFOA might influence sperm motility by altering Rab25. Differences in Rab34 were positively correlated with differences in acrosome-reacted spermatozoa, implicating its role in the acrosome reaction. These findings provided insights into the molecular mechanism of PFOA-induced reproductive toxicity and highlighted the function of Rab proteins as biomarkers for the assessment of the effects of similar environmental toxins on male fertility.

Unveiling the Molecular Effects of Replacement and Legacy PFASs: Transcriptomic Analysis of Zebrafish Embryos Reveals Surprising Similarities and Potencies

The prevalence of per- and poly fluoroalkyl substances (PFASs) in the environment has prompted restrictions on legacy PFASs due to their recognized toxic effects. Consequently, alternative "replacement" PFASs have been introduced and are prevalent in environmental matrices. Few studies have investigated the molecular effects of both legacy and replacement PFASs under short-term exposures. This study aimed to address this by utilizing transcriptomic sequencing to compare the molecular impacts of exposure to concentrations 0.001-5 mg/L of the legacy PFOS and two of its replacements, PFECHS and FBSA. Using zebrafish embryos, the research assessed apical effects (mortality, morphology, and growth), identified differentially expressed genes (DEGs) and enriched pathways, and determined transcriptomic points of departure (tPoDs) for each compound. Results indicated that PFOS exhibited the highest relative potency, followed by PFECHS and then FBSA. While similarities were observed among the ranked DEGs across all compounds, over-representation analysis revealed slight differences. Notably, PFOS demonstrated the lowest tPoD identified to date. These findings raise concerns regarding the safety of emerging replacement PFASs and challenge assumptions about PFAS toxicity solely resulting from their accumulative potential. As replacement PFASs proliferate in the environment, this study underscores the need for heightened scrutiny of their effects and questions current regulatory thresholds.

In vitro screening of understudied PFAS with a focus on lipid metabolism disruption

Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals used in many industrial applications. Exposure to PFAS is associated with several health risks, including a decrease in infant birth weight, hepatoxicity, disruption of lipid metabolism, and decreased immune response. We used the in vitro cell models to screen six less studied PFAS [perfluorooctane sulfonamide (PFOSA), perfluoropentanoic acid (PFPeA), perfluoropropionic acid (PFPrA), 6:2 fluorotelomer alcohol (6:2 FTOH), 6:2 fluorotelomer sulfonic acid (6:2 FTSA), and 8:2 fluorotelomer sulfonic acid (8:2 FTSA)] for their capacity to activate nuclear receptors and to cause differential expression of genes involved in lipid metabolism. Cytotoxicity assays were run in parallel to exclude that observed differential gene expression was due to cytotoxicity. Based on the cytotoxicity assays and gene expression studies, PFOSA was shown to be more potent than other tested PFAS. PFOSA decreased the gene expression of crucial genes involved in bile acid synthesis and detoxification, cholesterol synthesis, bile acid and cholesterol transport, and lipid metabolism regulation. Except for 6:2 FTOH and 8:2 FTSA, all tested PFAS downregulated PPARA gene expression. The reporter gene assay also showed that 8:2 FTSA transactivated the farnesoid X receptor (FXR). Based on this study, PFOSA, 6:2 FTSA, and 8:2 FTSA were prioritized for further studies to confirm and understand their possible effects on hepatic lipid metabolism.

Distribution and ecological risk assessment of perfluoroalkyl carboxylic acids (PFCAs) in the coastal river, China

Perfluoroalkyl carboxylic acids (PFCAs) enter surface waters through wastewater discharge and atmospheric deposition, accumulating within aquatic ecosystems and organisms, causing dysfunction or mortality. This study investigates the migration, sources and ecological risks of six PFCAs in the coastal Wulong River basin and the estuary along the eastern coast of China. The six PFCAs detected in the Wulong River included, at concentrations ranging from 17.36 to 57.92 ng/L. The distribution of PFCAs concentrations throughout the estuary were as follows: Northeast China (414.07 ng/L) > North China (325.97 ng/L) > East China (249.53 ng/L) > South China (63.61 ng/L), with perfluorooctanoic acid (PFOA) being the dominant PFCA. Toxicity data was collected for all detected PFCAs and the species sensitivity distribution (SSD) method was used to derive the predicted no effect concentrations (PNECs) for all six PFCAs. The risk quotient (RQ) method showed that the risk posed to aquatic organisms in the river basin from all six PFCAs was relatively low (RQ < 1). However, joint probability curve (JPC) analysis revealed that the probability of perfluoropentanoic acid (PFPeA) causing harm to 5% of aquatic species reached 41.13%. Considering the frequency of occurrence and persistence of PFCAs in aquatic environments, these findings indicate they have the potential to induce serious toxic effects on aquatic organisms.

Itaconic Acid Alleviates Perfluorooctanoic Acid-Induced Oxidative Stress and Intestinal Damage by Regulating the Keap1/Nrf2/Ho-1 Pathway and Reshaping the Gut Microbiota

Itaconic acid (IA) is recognized for its potential application in treating intestinal diseases owing to the anti-inflammatory and antioxidant properties. Perfluorooctanoic acid (PFOA) can accumulate in animals and result in oxidative and inflammatory damages to multi-tissue and organ, particularly in the intestinal tract. This study aimed to explore whether IA could mitigate intestinal damage induced by PFOA exposure in laying hens and elucidate its potential underlying mechanisms. The results showed that IA improved the antioxidant capacity of laying hens and alleviated the oxidative damage induced by PFOA, as evidenced by the elevated activities of T-SOD, GSH-Px, and CAT, and the decreased MDA content in both the jejunum and serum. Furthermore, IA improved the intestinal morphological and structural integrity, notably attenuating PFOA-induced villus shedding, length reduction, and microvillus thinning. IA also upregulated the mRNA expression of ZO-1, Occludin, Claudin-1, and Mucin-2 in the jejunum, thereby restoring intestinal barrier function. Compared with the PF group, IA supplementation downregulated the gene expression of Keap1 and upregulated the HO-1, NQO1, SOD1, and GPX1 expression in the jejunum. Meanwhile, the PF + IA group exhibited lower expressions of inflammation-related genes (NF-κB, IL-1β, IFN-γ, TNF-α, and IL-6) compared to the PF group. Moreover, IA reversed the PFOA-induced imbalance in gut microbiota by reducing the harmful bacteria such as Escherichia-Shigella, Clostridium innocuum, and Ruminococcus torques, while increasing the abundance of beneficial bacteria like Lactobacillus. Correlation analysis further revealed a significant association between gut microbes, inflammatory factors, and the Keap1/Nrf2/HO-1 pathway expression. In conclusion, dietary IA supplementation could alleviate the oxidative and inflammatory damage caused by PFOA exposure in the intestinal tract by reshaping the intestinal microbiota, modulating the Keap1/Nrf2/HO-1 pathway and reducing oxidative stress and inflammatory response, thereby promoting intestinal homeostasis.

Identification and quantification of novel per- and polyfluoroalkyl substances (PFAS) contamination in a Great Lakes urban-dominated watershed

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic organic fluoro-compounds that are oil-, water-, and flame-resistant, making them useful in a wide range of commercial and consumer products, as well as resistant to environmental degradation. To assess the impact of urbanization and wastewater treatment processes, surface water and sediment samples were collected at 27 sites within the Great Lakes in the Lake Huron to Lake Erie corridor (HEC), an international waterway including the highly urbanized Detroit and Rouge Rivers. Samples were analyzed for 92 PFAS via UHPLC-MS/MS. Our previous data in the HEC found the highest amount of PFAS contamination at the Rouge River mouth. In addition to evaluating the input of the Rouge River into the HEC, we evaluated the transport of PFAS into the HEC from other major tributaries. PFAS were detected in both surface water and sediment at all sites in this study, with a total of 10 congeners quantified in all surface water samples and 16 congeners quantified in all sediment samples, indicating ubiquitous contamination. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were pervasive in the HEC as these two compounds were detected in all sites and matrices, often at concentrations above the US EPA's recommended lifetime interim updated health advisories. Surface water samples contained more perfluorohexanoic acid (PFHxA) than any other congener, with average aqueous PFHxA across all surface water samples exceeding the average concentration previously reported in the Great Lakes. Sediment samples were dominated by PFOS, but novel congeners, notably 3-Perfluoropentyl propanoic acid (FPePA), were also quantified in sediment. The Rouge River and other tributaries contribute significantly to the PFAS burden in the HEC including Lake Erie. Overall, our results indicate the need for expanding toxicological research and risk assessment focused on congeners such as PFHxA and PFAS mixtures, as well as regulation that is tighter at the onset of production and encompasses PFAS as a group at a national level.

Structural investigation of the complexation between vitamin B12 and per- and polyfluoroalkyl substances: Insights into degradation using density functional theory

Environmental remediation of per- and polyfluoroalkyl substances (PFAS) has become a significant research topic in recent years due to the fact that these materials are omnipresent, resistant to degradation and thus environmentally persistent. Unfortunately, they have also been shown to cause health concerns. PFAS are widely used in industrial applications and consumer products. Vitamin B12 (B12) has been identified as being catalytically active towards a variety of halogenated compounds such as PFAS. It has also been shown to be effective when using sulfide as a reducing agent for B12. This is promising as sulfide is readily available in the environment. However, there are many unknowns with respect to PFAS interactions with B12. These include the reaction mechanism and B12's specificity for PFAS with certain functionalization(s). In order to understand the specificity of B12 towards branched PFAS, we examined the atomistic interactions between B12 and eight different PFAS molecules using Density Functional Theory (B3LYP/cc-pVDZ). The PFAS test set included linear PFAS and their branched analogs, carboxylic acid and sulfonic acid headgroups, and aromatic and non-aromatic cyclic structures. Conformational analyses were carried out to determine the lowest energy configurations. This analysis showed that small chain PFAS such as perfluorobutanoic acid interact with the cobalt center of B12. Bulkier PFAS prefer to interact with the amine and carbonyl groups on the sidechains of the B12 ring system. Furthermore, computed complexation energies determined that, in general, branched PFAS (e.g. perfluoro-5-methylheptane sulfonic acid) interact more strongly than linear molecules (e.g. perfluorooctanesulfonic acid). Our results indicate that it may be possible to alter the interactions between B12 and PFAS by synthetically modifying the sidechains of the ring structure.

Associations between co-exposure to per- and polyfluoroalkyl substances and organophosphate esters and erythrogram in Chinese adults

Erythrogram, despite its prevalent use in assessing red blood cell (RBC) disorders and can be utilized to evaluate various diseases, still lacks evidence supporting the effects of per- and polyfluoroalkyl substances (PFASs) and organophosphate esters (OPEs) on it. A cross-sectional study involving 467 adults from Shijiazhuang, China was conducted to assess the associations between 12 PFASs and 11 OPEs and the erythrogram (8 indicators related to RBC). Three models, including multiple linear regression (MLR), sparse partial least squares regression, and Bayesian kernel machine regression (BKMR) were employed to evaluate both the individual and joint effects of PFASs and OPEs on the erythrogram. Perfluorohexane sulfonic acid (PFHxS) showed the strongest association with HGB (3.68%, 95% CI: 2.29%, 5.10%) when doubling among PFASs in MLR models. BKMR indicated that PFASs were more strongly associated with the erythrogram than OPEs, as evidenced by higher group posterior inclusion probabilities (PIPs) for PFASs. Within hemoglobin and hematocrit, PFHxS emerged as the most significant component (conditional PIP = 1.0 for both). Collectively, our study emphasizes the joint effect of PFASs and OPEs on the erythrogram and identified PFASs, particularly PFHxS, as the pivotal contributors to the erythrogram. Nonetheless, further investigations are warranted to elucidate the underlying mechanisms.

The VDAC1 oligomerization regulated by ATP5B leads to the NLRP3 inflammasome activation in the liver cells under PFOS exposure

As a persistent organic pollutant, perfluorooctane sulfonate (PFOS) has a serious detrimental impact on human health. It has been suggested that PFOS is associated with liver inflammation. However, the underlying mechanisms are still unclear. Here, PFOS was found to elevate the oligomerization tendency of voltage-dependent anion channel 1 (VDAC1) in the mice liver and human normal liver cells L-02. Inhibition of VDAC1 oligomerization alleviated PFOS-induced nucleotide-binding domain and leucine-rich repeat protein-3 (NLRP3) inflammasome activation. Cytoplasmic membrane VDAC1 translocated to mitochondria was also observed in response to PFOS. Therefore, the oligomerization of VDAC1 occurred mainly in the mitochondria. VDAC1 was found to interact with the ATP synthase beta subunit (ATP5B) under PFOS treatment. Knockdown of ATP5B or immobilization of ATP5B to the cytoplasmic membrane alleviated the increased VDAC1 oligomerization and NLRP3 inflammasome activation. Therefore, our results suggested that PFOS induced NLRP3 inflammasome activation through VDAC1 oligomerization, a process dependent on ATP5B to transfer VDAC1 from the plasma membrane to the mitochondria. The findings offer novel perspectives on the activation of the NLRP3 inflammasome, the regulatory mode on VDAC1 oligomerization, and the mechanism of PFOS toxicity.

Stereoselective Bioconcentration and Neurotoxicity of Perfluoroethylcyclohexane Sulfonate in Marine Medaka

Perfluoroethylcyclohexane sulfonate (PFECHS) is an emerging per- and polyfluoroalkyl substance used to replace perfluorooctane sulfonate (PFOS), mainly in aircraft hydraulic fluids. However, previous research indicates the potential neurotoxicity of this replacement chemical. In this study, marine medaka (Oryzias melastigma) was exposed to environmentally relevant concentrations of PFECHS (concentrations: 0, 0.08, 0.26, and 0.91 μg/L) from the embryonic stage for 90 days. After exposure, the brain and eyes of the medaka were collected to investigate the bioconcentration potential of PFECHS stereoisomers and their effects on the nervous systems. The determined bioconcentration factors (BCFs) of PFECHS ranged from 324 ± 97 to 435 ± 89 L/kg and from 454 ± 60 to 576 ± 86 L/kg in the brain and eyes of medaka, respectively. The BCFs of trans-PFECHS were higher than those of cis-PFECHS. PFECHS exposure significantly altered γ-aminobutyric acid (GABA) levels in the medaka brain and disrupted the GABAergic system, as revealed by proteomics, implying that PFECHS can disturb neural signal transduction like PFOS. PFECHS exposure resulted in significant alterations in multiple proteins associated with eye function in medaka. Abnormal locomotion was observed in PFECHS-exposed medaka larvae, which was rescued by adding exogenous GABA, suggesting the involvement of disrupted GABA signaling pathways in PFECHS neurotoxicity.

Nontarget Analysis of Legacy and Emerging PFAS in a Lithium-Ion Power Battery Recycling Park and Their Possible Toxicity Measured Using High-Throughput Phenotype Screening

Driven by the global popularity of electric vehicles and the shortage of critical raw materials for batteries, the spent lithium-ion power battery (LIPB) recycling industry has exhibited explosive growth in both quantity and scale. However, relatively little information is known about the environmental risks posed by LIPB recycling, in particular with regards to perfluoroalkyl and polyfluoroalkyl substances (PFAS). In this work, suspect screening and nontarget analysis were carried out to characterize PFAS in soil, dust, water and sediment from a LIPB recycling area. Twenty-five PFAS from nine classes were identified at confidence level 3 or above, including 13 legacy and 12 emerging PFAS, as well as two ultrashort-chain PFAS. Based on the target analysis of 16 PFAS, at least nine were detected in each environmental sample, indicating their widespread presence in a LIPB recycling area. Perfluorodecanoic acid, perfluorooctanesulfonic acid and trifluoromethanesulfonamide showed significant differences in the four phenotypic parameters (growth, movement, survival and fecundity) of Caenorhabditis elegans and were the most toxic substances in all target PFAS at an exposure concentration of 200 μM. Our project provides first-hand information on the existence and environmental risk of PFAS, facilitating the formulation of regulations and green development of the LIPB recycling industry.

Perfluorooctane sulfonate induces ferroptosis-dependent non-alcoholic steatohepatitis via autophagy-MCU-caused mitochondrial calcium overload and MCU-ACSL4 interaction

The incidence of nonalcoholic steatohepatitis (NASH) is related with perfluorooctane sulfonate (PFOS), yet the mechanism remains ill-defined. Mounting evidence suggests that ferroptosis plays a crucial role in the initiation of NASH. In this study, we used mice and human hepatocytes L-02 to investigate the role of ferroptosis in PFOS-induced NASH and the effect and molecular mechanism of PFOS on liver ferroptosis. We found here that PFOS caused NASH in mice, and lipid accumulation and inflammatory response in the L-02 cells. PFOS induced hepatic ferroptosis in vivo and in vitro, as evidenced by the decrease in glutathione peroxidase 4 (GPX4), and the increases in cytosolic iron, acyl-CoA synthetase long-chain family member 4 (ACSL4) and lipid peroxidation. In the PFOS-treated cells, the increases in the inflammatory factors and lipid contents were reversed by ferroptosis inhibitor. PFOS-induced ferroptosis was relieved by autophagy inhibitor. The expression of mitochondrial calcium uniporter (MCU) was accelerated by PFOS, leading to subsequent mitochondrial calcium accumulation, and inhibiting autophagy reversed the increase in MCU. Inhibiting mitochondrial calcium reversed the variations in GPX4 and cytosolic iron, without influencing the change in ACSL4, induced by PFOS. MCU interacted with ACSL4 and the siRNA against MCU reversed the changes in ACSL4，GPX4 and cytosolic iron systemically. This study put forward the involvement of hepatic ferroptosis in PFOS-induced NASH and identified MCU as the mediator of the autophagy-dependent ferroptosis.

Investigation of Peroxisome Proliferator-Activated Receptor Genes as Requirements for Visual Startle Response Hyperactivity in Larval Zebrafish Exposed to Structurally Similar Per- and Polyfluoroalkyl Substances (PFAS)

BACKGROUND

Per- and polyfluoroalkyl Substances (PFAS) are synthetic chemicals widely detected in humans and the environment. Exposure to perfluorooctanesulfonic acid (PFOS) or perfluorohexanesulfonic acid (PFHxS) was previously shown to cause dark-phase hyperactivity in larval zebrafish.

OBJECTIVES

The objective of this study was to elucidate the mechanism by which PFOS or PFHxS exposure caused hyperactivity in larval zebrafish.

METHODS

Swimming behavior was assessed in 5-d postfertilization (dpf) larvae following developmental (1-4 dpf) or acute (5 dpf) exposure to 0.43 - 7.86 μ M PFOS, 7.87 - 120 μ M PFHxS, or 0.4% dimethyl sulfoxide (DMSO). After developmental exposure and chemical washout at 4 dpf, behavior was also assessed at 5-8 dpf. RNA sequencing was used to identify differences in global gene expression to perform transcriptomic benchmark concentration-response (BMC T ) modeling, and predict upstream regulators in PFOS- or PFHxS-exposed larvae. CRISPR/Cas9-based gene editing was used to knockdown peroxisome proliferator-activated receptors (ppars) pparaa/ab, pparda/db, or pparg at day 0. Knockdown crispants were exposed to 7.86 μ M PFOS or 0.4% DMSO from 1-4 dpf and behavior was assessed at 5 dpf. Coexposure with the ppard antagonist GSK3787 and PFOS was also performed.

RESULTS

Transient dark-phase hyperactivity occurred following developmental or acute exposure to PFOS or PFHxS, relative to the DMSO control. In contrast, visual startle response (VSR) hyperactivity only occurred following developmental exposure and was irreversible up to 8 dpf. Similar global transcriptomic profiles, BMC T estimates, and enriched functions were observed in PFOS- and PFHxS-exposed larvae, and ppars were identified as putative upstream regulators. Knockdown of pparda/db, but not pparaa/ab or pparg, blunted PFOS-dependent VSR hyperactivity to control levels. This finding was confirmed via antagonism of ppard in PFOS-exposed larvae.

DISCUSSION

This work identifies a novel adverse outcome pathway for VSR hyperactivity in larval zebrafish. We demonstrate that developmental, but not acute, exposure to PFOS triggered persistent VSR hyperactivity that required ppard function. https://doi.org/10.1289/EHP13667.

Perfluorooctanesulfonic acid exposure leads to downregulation of 3-hydroxy-3-methylglutaryl-CoA synthase 2 expression and upregulation of markers associated with intestinal carcinogenesis in mouse intestinal tissues

Perfluorooctanesulfonic acid (PFOS) is a widely recognized environment pollutant known for its high bioaccumulation potential and a long elimination half-life. Several studies have shown that PFOS can alter multiple biological pathways and negatively affect human health. Considering the direct exposure to the gastrointestinal (GI) tract to environmental pollutants, PFOS can potentially disrupt intestinal homeostasis. However, there is limited knowledge about the effect of PFOS exposure on normal intestinal tissues, and its contribution to GI-associated diseases remains to be determined. In this study, we examined the effect of PFOS exposure on the gene expression profile of intestinal tissues of C57BL/6 mice using RNAseq analysis. We found that PFOS exposure in drinking water significantly downregulates mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a rate-limiting ketogenic enzyme, in intestinal tissues of mice. We found that diets containing the soluble fibers inulin and pectin, which are known to be protective against PFOS exposure, were ineffective in reversing the downregulation of HMGCS2 expression in vivo. Analysis of intestinal tissues also demonstrated that PFOS exposure leads to upregulation of proteins implicated in colorectal carcinogenesis, including β-catenin, c-MYC, mTOR and FASN. Consistent with the in vivo results, PFOS exposure leads to downregulation of HMGCS2 in mouse and human normal intestinal organoids in vitro. Furthermore, we show that shRNA-mediated knockdown of HMGCS2 in a human normal intestinal cell line resulted in increased cell proliferation and upregulation of key proliferation-associated proteins such as cyclin D, survivin, ERK1/2 and AKT, along with an increase in lipid accumulation. In summary, our results suggest that PFOS exposure may contribute to pathological changes in normal intestinal cells via downregulation of HMGCS2 expression and upregulation of pro-carcinogenic signaling pathways that may increase the risk of colorectal cancer development.

Gradual effects of gradient concentrations of perfluorooctane sulfonate on the antioxidant ability and gut microbiota of red claw crayfish (Cherax quadricarinatus)

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant that is characterized by environmental persistence, bioaccumulation, and toxicity. In this study, we investigated the gut microbial response of the red claw crayfish Cherax quadricarinatus after 28 days of exposure to 0 ng/L, 1 ng/L, 10 μg/L, or 10 mg/L of PFOS as a stressor. We measured oxidative stress-related enzyme activities and expression of molecules related to detoxification mechanisms to evaluate the toxic effects of PFOS. We found that PFOS disturbed microbial homeostasis in the gut of C. quadricarinatus, resulting in increased abundance of the pathogen Shewanella and decreased abundance of the beneficial bacterium Lactobacillus. The latter especially disturbed amino acid transport and carbohydrate transport. We also found that the activities of glutathione S-transferase and glutathione peroxidase were positively correlated with the expression levels of cytochrome P450 genes (GST1-1, GSTP, GSTK1, HPGDS, UGT5), which are products of PFOS-induced oxidative stress and play an antioxidant role in the body. The results of this study provided valuable ecotoxicological data to better understand the biological fate and effects of PFOS in C. quadricarinatus.

Perfluoroalkyl sulfonate induces cardiomyocyte apoptosis via endoplasmic reticulum stress activation and autophagy flux inhibition

Perfluoroalkyl sulfonate (PFOS) is a commonly used chemical compound that often found in materials such as waterproofing agents, food packaging, and fire retardants. Known for its stability and persistence in the environment, PFOS can enter the human body through various pathways, including water and the food chain, raising concerns about its potential harm to human health. Previous studies have suggested a cardiac toxicity of PFOS, but the specific cellular mechanisms remained unclear. Here, by using AC16 cardiomyocyte as a model to investigate the molecular mechanisms potential the cardiac toxicity of PFOS. Our findings revealed that PFOS exposure reduced cell viability and induces apoptosis in human cardiomyocyte. Proteomic analysis and molecular biological techniques showed that the Endoplasmic Reticulum (ER) stress-related pathways were activated, while the cellular autophagy flux was inhibited in PFOS-exposed cells. Subsequently, we employed strategies such as autophagy activation and ER stress inhibition to alleviate the PFOS-induced apoptosis in AC16 cells. These results collectively suggest that PFOS-induced ER stress activation and autophagy flux inhibition contribute to cardiomyocyte apoptosis, providing new insights into the mechanisms of PFOS-induced cardiomyocyte toxicity.

Species Difference? Bovine, Trout, and Human Plasma Protein Binding of Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) strongly bind to proteins and lipids in blood, which govern their accumulation and distribution in organisms. Understanding the plasma binding mechanism and species differences will facilitate the quantitative in vitro-to-in vivo extrapolation and improve risk assessment of PFAS. We studied the binding mechanism of 16 PFAS to bovine serum albumin (BSA), trout, and human plasma using solid-phase microextraction. Binding of anionic PFAS to BSA and human plasma was found to be highly concentration-dependent, while trout plasma binding was linear for the majority of the tested PFAS. At a molar ratio of PFAS to protein ν < 0.1 molPFAS/molprotein, the specific protein binding of anionic PFAS dominated their human plasma binding. This would be the scenario for physiological conditions (ν < 0.01), whereas in in vitro assays, PFAS are often dosed in excess (ν > 1) and nonspecific binding becomes dominant. BSA was shown to serve as a good surrogate for human plasma. As trout plasma contains more lipids, the nonspecific binding to lipids affected the affinities of PFAS for trout plasma. Mass balance models that are parameterized with the protein-water and lipid-water partitioning constants (chemical characteristics), as well as the protein and lipid contents of the plasma (species characteristics), were successfully used to predict the binding to human and trout plasma.

Rim-Based Binding of Perfluorinated Acids to Pillararenes Purifies Water

Per- and polyfluoroalkyl substances (PFAS) pose a rapidly increasing global problem as their widespread use and high stability lead worldwide to water contamination, with significant detrimental health effects.[1] Supramolecular chemistry has been invoked to develop materials geared towards the specific capture of PFAS from water,[2] to reduce the concentration below advisory safety limits (e.g., 70 ng/L for the sum of perfluorooctane sulfonic acid, PFOS and perfluorooctanoic acid, PFOA). Scale-up and use in natural waters with high PFAS concentrations has hitherto posed a problem. Here we report a new type of host-guest interaction between deca-ammonium-functionalized pillar[5]arenes (DAF-P5s) and perfluoroalkyl acids. DAF-P5 complexes show an unprecedented 1 : 10 stoichiometry, as confirmed by isothermal calorimetry and X-ray crystallographic studies, and high binding constants (up to 106 M-1) to various polyfluoroalkyl acids. In addition, non-fluorinated acids do not hamper this process significantly. Immobilization of DAF-P5s allows a simple single-time filtration of PFAS-contaminated water to reduce the PFOS/PFOA concentration 106 times to 15-50 ng/L level. The effective and fast (<5 min) orthogonal binding to organic molecules without involvement of fluorinated supramolecular hosts, high breakthrough capacity (90 mg/g), and robust performance (>10 regeneration cycles without decrease in performance) set a new benchmark in PFAS-absorbing materials.

Exposure to polystyrene microplastics and perfluorooctane sulfonate disrupt the homeostasis of intact planarians and the growth of regenerating planarians

Microplastics (MPs) and perfluorinated compounds (PFAS) are widespread in the global ecosystem. MPs have the ability to adsorb organic contaminants such as perfluorooctane sulfonate (PFOS), leading to combined effects. The current work aims to explore the individual and combined toxicological effects of polystyrene (PS) and PFOS on the growth and nerves of the freshwater planarian (Dugesia japonica). The results showed that PS particles could adsorb PFOS. PS and PFOS impeded the regeneration of decapitated planarians eyespots, whereas the combined treatment increased the locomotor speed of intact planarians. PS and PFOS caused significant DNA damage, while co-treatment with different PS concentrations aggravated and attenuated DNA damage, respectively. Further studies at the molecular level have shown that PS and PFOS affect the proliferation and differentiation of neoblasts in both intact and regenerating planarians, alter the expression levels of neuronal genes, and impede the development of the nervous system. PS and PFOS not only disrupted the homeostasis of intact planarians, but also inhibited the regeneration of decapitated planarians. This study is the first to assess the multiple toxicity of PS and PFOS to planarians after combined exposure. It provides a basis for the environmental and human health risks of MPs and PFAS.

Amino Group-Driven Adsorption of Sodium p-Perfluorous Nonenoxybenzene Sulfonate in Water by the Modified Graphene Oxide

Sodium p-perfluorous nonenoxybenzene sulfonate (OBS) is one of the key alternatives to perfluoroalkyl substances (PFASs). Its widespread tendency has increased extensive contamination in the aquatic environment. However, the present treatment technology for OBS exhibited insignificant adsorption capacity and long adsorption time. In this study, three proportions (1:5, 3:5, and 10:1) of chitosan-modified amino-driven graphene oxide (CS-GO) were innovated to strengthen the OBS adsorption capacity, compared with graphene oxide (GO) and graphene (GH). Through the characterization of SEM, BET, and FTIR, it was discovered that CS was synthetized on GO surfaces successfully with a low specific surface area. Subsequently, batch single influence factor studies on OBS removal from simulated wastewater were investigated. The optimum removal efficiency of OBS could be achieved up to 95.4% within 2 h when the adsorbent was selected as CS-GO (10:1), the dosage was 2 mg, and the pH was 3. The addition of inorganic ions could promote the adsorption efficiency of OBS. In addition, CS-GO presented the maximum adsorption energy due to additional functional groups of -NH3, and electrostatic interaction was the foremost motive for improving the adsorption efficiency of OBS. Moreover, OBS exhibited the fastest diffusion coefficient in the CS-GO-OBS solution, which is consistent with the fitting results of adsorption kinetics.

Hepatic injury and ileitis associated with gut microbiota dysbiosis in mice upon F-53B exposure

Chlorinated polyfluorinated ether sulfonate (F-53B), a substitute of perfluorooctane sulfonic acid (PFOS), has attracted significant attention for its link to hepatotoxicity and enterotoxicity. Nevertheless, the underlying mechanisms of F-53B-induced enterohepatic toxicity remain incompletely understood. This study aimed to explore the role of F-53B exposure on enterohepatic injury based on the gut microbiota, pathological and molecular analysis in mice. Here, we exposed C57BL/6 mice to F-53B (0, 4, 40, and 400 μg/L) for 28 days. Our findings revealed a significant accumulation of F-53B in the liver, followed by small intestines, and feces. In addition, F-53B induced pathological collagen fiber deposition and lipoid degeneration, up-regulated the expression of fatty acid β-oxidation-related genes (PPARα and PPARγ, etc), while simultaneously down-regulating pro-inflammatory genes (Nlrp3, IL-1β, and Mcp1) in the liver. Meanwhile, F-53B induced ileal mucosal barrier damage, and an up-regulation of pro-inflammatory genes and mucosal barrier-related genes (Muc1, Muc2, Claudin1, Occludin, Mct1, and ZO-1) in the ileum. Importantly, F-53B distinctly altered gut microbiota compositions by increasing the abundance of Akkermansia and decreasing the abundance of Prevotellaceae_NK3B31_group in the feces. F-53B-altered microbiota compositions were significantly associated with genes related to fatty acid β-oxidation, inflammation, and mucosal barrier. In summary, our results demonstrate that F-53B is capable of inducing hepatic injury, ileitis, and gut microbiota dysbiosis in mice, and the gut microbiota dysbiosis may play an important role in the F-53B-induced enterohepatic toxicity.

Modulating the ion-transfer electrochemistry of perfluorooctanoate with serum albumin and β-cyclodextrin

Per- and polyfluoroalkyl substances (PFAS) are durable synthetic pollutants that persist in the environment and resist biodegradation. Ion-transfer electrochemistry at aqueous-organic interfaces is a simple strategy for the detection of ionised PFAS. Herein, we investigate the modulation of the ion transfer voltammetry of perfluorooctanoate (PFOA) at liquid-liquid micro-interface arrays by aqueous phase bovine serum albumin (BSA) or β-cyclodextrin (β-CD) and examine the determination of association constants for these binding interactions. By tracking the ion transfer current due to ionised, uncomplexed PFOA as a function of BSA or β-CD concentration, titration curves are produced. Fitting of a binding isotherm to these data provides the association constants. The association constant of PFOA with the BSA determined in this way was ca. 105 M-1 assuming a 1 : 1 binding. Likewise, the association constant for PFOA with β-CD was ca. 104 M-1 for a 1 : 1 β-CD-PFOA complex. Finally, the simultaneous effect of both BSA and β-CD on the ion transfer voltammetry of PFOA was studied, showing clearly that PFOA bound to BSA is released (de-complexed) upon addition of β-CD. The results presented here show ion transfer voltammetry as a simple strategy for the study of molecular and biomolecular binding of ionised PFAS and is potentially useful in understanding the affinity of different PFAS with aqueous phase binding agents such as proteins and carbohydrates.

Lipid responses to perfluorooctane sulfonate exposure for multiple rat organs

Perfluorooctane sulfonate (PFOS) is a persistent chemical that has long been a threat to human health. However, the molecular effects of PFOS on various organs are not well studied. In this study, male Sprague-Dawley rats were treated with various doses of PFOS through gavage for 21 days. Subsequently, the liver, lung, heart, kidney, pancreas, testis, and serum of the rats were harvested for lipid analysis. We applied a focusing lipidomic analytical strategy to identify key lipid responses of phosphorylcholine-containing lipids, including phosphatidylcholines and sphingomyelins. Partial least squares discriminant analysis revealed that the organs most influenced by PFOS exposure were the liver, kidney, and testis. Changes in the lipid profiles of the rats indicated that after exposure, levels of diacyl-phosphatidylcholines and 22:6-containing phosphatidylcholines in the liver, kidney, and testis of the rats decreased, whereas the level of 20:3-containing phosphatidylcholines increased. Furthermore, levels of polyunsaturated fatty acids-containing plasmenylcholines decreased. Changes in sphingomyelin levels indicated organ-dependent responses. Decreased levels of sphingomyelins in the liver, nonmonotonic dose responses in the kidney, and irregular responses in the testis after PFOS exposure are observed. These lipid responses may be associated with alterations pertaining to phosphatidylcholine synthesis, fatty acid metabolism, membrane properties, and oxidative stress in the liver, kidney, and testis. Lipid responses in the liver could have contributed to the observed increase in liver to body weight ratios. The findings suggest potential toxicity and possible mechanisms associated with PFOS in multiple organs.

Effect of liver cancer on the accumulation and hepatobiliary transport of per- and polyfluoroalkyl substances

In this study, we examined the distribution of per- and polyfluoroalkyl substances (PFASs) in liver and bile tissues from the patients with liver cancer (n = 202) and healthy controls (n = 30), and calculated the hepatobiliary transport efficiency (TB-L) of PFASs. Among 21 PFASs, 13 PFASs were frequently detected in the liver (median: 8.80-16.3 ng/g) and bile (median: 11.03-14.26 ng/mL) samples. PFAS concentrations in liver were positively correlated with age, with higher levels of PFASs in the older. Variance analysis showed that gender and BMI (Body Mass Index) have an important impact on the distribution of PFASs. A U-shaped trend in TB-L of PFASs with the increasing of carbon chain length was found for the first time, and the TB-L of most PFASs in the control was higher than that of those in cases (p < 0.05), suggesting that hepatic injury would affect their transport. PFASs were positively associated with liver injury biomarkers, including γ-glutamyl transferase (GGT), alanine aminotransferase (ALT), and total bilirubin (TB) levels (p < 0.05). This is the first study on examining the hepatobiliary transport characteristics of PFASs, which may help understand the connection between PFAS accumulation and liver cancer risk.

Threats of per- and poly-fluoroalkyl pollutants to susceptible populations

Environmental exposure to per- and poly-fluoroalkyl substances (PFAS) has raised significant global health concerns due to potential hazards in healthy adults. However, the impact of PFAS on susceptible populations, including pregnant individuals, newborns, the older people, and those with underlying health conditions, has been overlooked. These susceptible groups often have physiological changes that make them less resilient to the same exposures. Consequently, there is an urgent need for a comprehensive understanding of the health risks posed by PFAS exposure to these populations. In this review, we delve into the potential health risks of PFAS exposure in these susceptible populations. Equally important, we also examine and discuss the molecular mechanisms that underlie this susceptibility. These mechanisms include the induction of oxidative stress, disruption of the immune system, impairment of cellular metabolism, and alterations in gut microbiota, all of which contribute to the enhanced toxicity of PFAS in susceptible populations. Finally, we address the primary research challenges and unresolved issues that require further investigation. This discussion aims to foster research for a better understanding of how PFAS affect susceptible populations and to pave the way for strategies to minimize their adverse effects.

Perfluorooctanoic acid induces cardiac dysfunction in human induced pluripotent stem cell-derived cardiomyocytes

Perfluorooctanoic acid (PFOA), commonly found in drinking water, leads to widespread exposure through skin contact, inhalation, and ingestion, resulting in detectable levels of PFOA in the bloodstream. In this study, we found that exposure to PFOA disrupts cardiac function in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). We observed reductions in field and action potentials in hiPSC-CMs exposed to PFOA. Furthermore, PFOA demonstrated a dose-dependent inhibitory effect on various ion channels, including the calcium, sodium, and potassium channels. Additionally, we noted dose-dependent inhibition of the expression of these ion channels in hiPSC-CMs following exposure to PFOA. These findings suggest that PFOA exposure can impair cardiac ion channel function and decrease the transcription of genes associated with these channels, potentially contributing to cardiac dysfunction such as arrhythmias. Our study sheds light on the electrophysiological and epigenetic consequences of PFOA-induced cardiac dysfunction, underscoring the importance of further research on the cardiovascular effects of perfluorinated compounds (PFCs).

Current state of knowledge of environmental occurrence, toxic effects, and advanced treatment of PFOS and PFOA

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic synthetic compounds, with high chemical and thermal stability and a persistent, stable and bioaccumulative nature that renders them a potential hazard for the environment, its organisms, and humans alike. Perfluorooctane sulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are the most well-known substances of this category and even though they are phased out from production they are still highly detectable in several environmental matrices. As a result, they have been spread globally in water sources, soil and biota exerting toxic and detrimental effects. Therefore, up and coming technologies, namely advanced oxidation processes (AOPs) and advanced reduction processes (ARPs) are being tested for their implementation in the degradation of these pollutants. Thus, the present review compiles the current knowledge on the occurrence of PFOS and PFOA in the environment, the various toxic effects they have induced in different organisms as well as the ability of AOPs and ARPs to diminish and/or eliminate them from the environment.

PFAS: exploration of neurotoxicity and environmental impact

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants stemming from various industrial and consumer products, posing a grave threat to both human health and ecosystems. PFAS contamination arises from multiple sources, including industrial effluents, packaging, and product manufacturing, accumulating in plants and impacting the food chain. Elevated PFAS levels in water bodies pose significant risks to human consumption. This review focuses on PFAS-induced neurological effects, highlighting disrupted dopamine signalling and structural neuron changes in humans. Animal studies reveal apoptosis and hippocampus dysfunction, resulting in memory loss and spatial learning issues. The review introduces the BKMR model, a machine learning technique, to decipher intricate PFAS-neurotoxicity relationships. Epidemiological data underscores the vulnerability of young brains to PFAS exposure, necessitating further research. Stricter regulations, industry monitoring, and responsible waste management are crucial steps to reduce PFAS exposure.

The interaction of perfluorooctane sulfonate with hemoproteins and its relevance to molecular toxicology

Perfluorooctane sulfonate (PFOS), a representative of perfluorinated compounds in industrial and commercial products, has posed a great threat to animals and humans via environmental exposure and dietary consumption. Herein, we investigated the effects of PFOS binding on the redox state and stability of two hemoproteins (hemoglobin (Hb) and myoglobin (Mb)). Fluorescence spectroscopy, circular dichroism and UV-vis absorption spectroscopy demonstrated that PFOS could induce the conformational changes of proteins along with the exposure of heme cavity and generation of hemichrome, which resulted in the increased release of free hemin. After that, free hemin liberated from hemoproteins led to reactive oxygen species formation, lipid peroxidation, cell membrane damage and loss of cell viability in vascular endothelial cells, while neither Hb nor Mb did show cytotoxicity. Chemical inhibitors of ferroptosis effectively mitigated hemin-caused toxicity, identifying the hemin-dependent ferroptotic cell death mechanisms. These data demonstrated that PFOS posed a potential threat of toxicity through a mechanism which involved its binding to hemoproteins, decreased oxygen transporting capacity, and increased hemin release. Altogether, our findings elucidate the binding mechanisms of PFOS with two hemoproteins, as well as possible risks on vascular endothelial cells, which would have important implications for the human and environmental toxicity of PFOS.

Early life exposure to perfluorooctanesulfonate (PFOS) impacts vital biological processes in Xenopus laevis: Integrated morphometric and transcriptomic analyses

Perfluorooctanesulfonate (PFOS) is a ubiquitous environmental pollutant associated with increasing health concerns and environmental hazards. Toxicological analyses of PFOS exposure are hampered by large interspecies variations and limited studies on the mechanistic details of PFOS-induced toxicity. We investigated the effects of PFOS exposure on Xenopus laevis embryos based on the reported developmental effects in zebrafish. X. laevis was selected to further our understanding of interspecies variation in response to PFOS, and we built upon previous studies by including transcriptomics and an assessment of ciliogenic effects. Midblastula-stage X. laevis embryos were exposed to PFOS using the frog embryo teratogenesis assay Xenopus (FETAX). Results showed teratogenic effects of PFOS in a time- and dose-dependent manner. The morphological abnormalities of skeleton deformities, a small head, and a miscoiled gut were associated with changes in gene expression evidenced by whole-mount in situ hybridization and transcriptomics. The transcriptomic profile of PFOS-exposed embryos indicated the perturbation in the expression of genes associated with cell death, and downregulation in adenosine triphosphate (ATP) biosynthesis. Moreover, we observed the effects of PFOS exposure on cilia development as a reduction in the number of multiciliated cells and changes in the directionality and velocity of the cilia-driven flow. Collectively, these data broaden the molecular understanding of PFOS-induced developmental effects, whereby ciliary dysfunction and disrupted ATP synthesis are implicated as the probable modes of action of embryotoxicity. Furthermore, our findings present a new challenge to understand the links between PFOS-induced developmental toxicity and vital biological processes.

Adipogenic and osteogenic effects of OBS and synergistic action with PFOS via PPARγ-RXRα heterodimers

Sodium p-perfluorous nonenoxybenzenesulfonate (OBS) is a novel alternative to perfluorooctane sulfonate (PFOS), with environmental health risks largely unknown. The present study aims to unravel the adipogenesis effects and underlying molecular initiating events of OBS, which are crucial for understanding and predicting its adverse outcome. In undifferentiated human mesenchymal stem cells (hMSCs), exposure to 1-100 nM of OBS for 7 days stimulated reactive oxygen species production. In the subsequent multipotent differentiation, hMSCs favored adipogenesis and repressed osteogenesis. The point of departure (PoD) for cellular responses of OBS was 38.85 nM, higher than PFOS (0.39 nM). Notably, OBS/PFOS co-exposure inhibited osteogenesis and synergistically promoted adipogenesis. Consistently, the expression of adipogenic marker genes was up-regulated, while that of osteogenic marker genes was down-regulated. The decreased adiponectin and elevated tumor necrosis factor α (TNFα) secretion were observed in differentiated cells exposed to the mixture of OBS and PFOS. The co-treatment of a peroxisome proliferator-activated receptor γ (PPARγ) antagonist alleviated the adipogenic effects of PFOS and its combination with OBS. Moreover, OBS/PFOS co-exposure induced peroxisome PPARγ activation in reporter gene assays, and increased formation of PPARγ - retinoid X receptor α (RXRα) heterodimers measured by co-immunoprecipitation assays. Molecular docking showed interaction energy of OBS (-20.7 kcal/mol) with intact PPARγ-RXRα complex was lower than that of PFOS (-25.9 kcal/mol). Overall, single OBS exhibited lower potency in inducing adipogenesis but is comparable to PFOS in repressing osteogenesis, whereas OBS/PFOS co-exposure increases interaction with PPARγ-RXRα heterodimers, resulting in the synergistic activation of PPARγ, ultimately enhancing adipogenesis at the expense of osteogenic differentiation. The results indicate the potential health risks of increased obesity and decreased bone density caused by OBS and its co-exposure with PFOS, as well as other perfluorinated alkylated substances mixtures.

PFAS Electroanalysis in Low-Oxygen River Water Using Electrogenerated Dioxygen

Per- and polyfluoroalkyl substances (PFAS), nicknamed "forever chemicals" due to the strength of their carbon-fluorine bonds, are a class of potent micropollutants that cause deleterious health effects in mammals. The current state-of-the-art detection method requires the collection and transport of water samples to a centralized facility where chromatography and mass spectrometry are performed for the separation, identification, and quantification of PFAS. However, for efficient remediation efforts to be properly informed, a more rapid in-field testing method is required. We previously demonstrated the development and use of dioxygen as the mediator molecule. The use of dioxygen is predicated on the assumption that there will be consistent ambient dioxygen levels in natural waters. This is not always the case in hypoxic groundwater and at high altitudes. To overcome this challenge and further advance the strategies that will enable in-field electroanalysis of PFAS, we demonstrate, as a proof of concept, that dioxygen can be generated in solution through the hydrolysis of water. The electrogenerated dioxygen can then be used as a mediator molecule for the indirect detection of PFOS via molecularly imprinted polymer (MIP)-based electroanalysis. We demonstrate that calibration curves can be constructed with high precision and sensitivity (LOD < 1 ppt or 1 ng/L). Our results provide a foundation for enabling in-field hypoxic PFAS electroanalysis.

J-Aggregate-Triggering BODIPYs: an Ultrasensitive Chromogenic and Fluorogenic Sensing Platform for Perfluorooctanesulfonate

Contamination of water supplies by polyfluoroalkyl substances, notably perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), has serious health and environmental consequences. Therefore, the development of straightforward and effective means of monitoring and removing PFASs is urgently required. In this study, we report a rapid and sensitive method for the detection of PFOS and PFOA in water that rely on the J-aggregate formation of meso-ester-BODIPY dyes. The dye C10-mim, which contains a hydrophilic methylimidazolium group and a hydrophobic alkylated BODIPY, self-assembles in water into weakly green-emissive micellar assemblies. Upon binding to PFOS or PFOA, a spontaneous disassembly and reorganization forms orange-emissive J-aggregates. The rapid formation (≤5 s) of J-aggregates and the accompanying spectral shifts provide a superior sensing performance, with excellent sensitivity (limit of detection=0.18 ppb for PFOS) and distinct chromogenic and fluorogenic "turn-on" responses.

Binding of Per- and Polyfluoroalkyl Substances (PFAS) to the PPARγ/RXRα-DNA Complex

Nuclear receptors are the fundamental building blocks of gene expression regulation and the focus of many drug targets. While binding to DNA, nuclear receptors act as transcription factors, governing a multitude of functions in the human body. Peroxisome proliferator-activator receptor γ (PPARγ) and the retinoid X receptor α (RXRα) form heterodimers with unique properties and have a primordial role in insulin sensitization. This PPARγ/RXRα heterodimer has been shown to be impacted by per- and polyfluoroalkyl substances (PFAS) and linked to a variety of significant health conditions in humans. Herein, a selection of the most common PFAS (legacy and emerging) was studied utilizing molecular dynamics simulations for PPARγ/RXRα. The local and global structural effects of PFAS binding on the known ligand binding pockets of PPARγ and RXRα as well as the DNA binding domain (DBD) of RXRα were inspected. The binding free energies were predicted computationally and were compared between the different binding pockets. In addition, two electronic structure approaches were utilized to model the interaction of PFAS within the DNA binding domain, density functional theory (DFT) and domain-based pair natural orbital coupled cluster with perturbative triples (DLPNO-CCSD(T)) approaches, with implicit solvation. Residue decomposition and hydrogen-bonding analysis were also performed, detailing the role of prominent residues in molecular recognition. The role of l-carnitine is explored as a potential in vivo remediation strategy for PFAS interaction with the PPARγ/RXRα heterodimer. In this work, it was found that PFAS can bind and act as agonists for all of the investigated pockets. For the first time in the literature, PFAS are postulated to bind to the DNA binding domain in a nonspecific manner. In addition, for the PPARγ ligand binding domain, l-carnitine shows promise in replacing smaller PFAS from the pocket.

Exploring Route-Specific Pharmacokinetics of PFAS in Mice by Coupling in Vivo Tests and Physiologically Based Toxicokinetic Models

BACKGROUND

Oral ingestion, inhalation, and skin contact are important exposure routes for humans to uptake per- and polyfluoroalkyl substances (PFAS). However, nasal and dermal exposure to PFAS remains unclear, and accurately predicting internal body burden of PFAS in humans via multiple exposure pathways is urgently required.

OBJECTIVES

We aimed to develop multiple physiologically based toxicokinetic (PBTK) models to unveil the route-specific pharmacokinetics and bioavailability of PFAS via respective oral, nasal, and dermal exposure pathways using a mouse model and sought to predict the internal concentrations in various tissues through multiple exposure routes and extrapolate it to humans.

METHODS

Mice were administered the mixed solution of perfluorohexane sulfonate, perfluorooctane sulfonate, and perfluorooctanoic acid through oral, nasal, and dermal exposure separately or jointly. The time-dependent concentrations of PFAS in plasma and tissues were determined to calibrate and validate the individual and combined PBTK models, which were applied in single- and repeated-dose scenarios.

RESULTS

The developed route-specific PBTK models successfully simulated the tissue concentrations of PFAS in mice following single or joint exposure routes as well as long-term repeated dose scenarios. The time to peak concentration of PFAS in plasma via dermal exposure was much longer (34.1-83.0 h) than that via nasal exposure (0.960 h). The bioavailability of PFAS via oral exposure was the highest (73.2%-98.0%), followed by nasal (33.9%-66.8%) and dermal exposure (4.59%-7.80%). This model was extrapolated to predict internal levels in human under real environment.

DISCUSSION

Based on these data, we predict the following: PFAS were absorbed quickly via nasal exposure, whereas a distinct hysteresis effect was observed for dermal exposure. Almost all the PFAS to which mice were exposed via gastrointestinal route were absorbed into plasma, which exhibited the highest bioavailability. Exhalation clearance greatly depressed the bioavailability of PFAS via nasal exposure, whereas the lowest bioavailability in dermal exposure was because of the interception of PFAS within the skin layers. https://doi.org/10.1289/EHP11969.

Evaluation of Neural Regulation and Microglial Responses to Brain Injury in Larval Zebrafish Exposed to Perfluorooctane Sulfonate

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are biopersistent, global pollutants. Although some in vitro and epidemiological studies have explored the neurotoxic potential of perfluorooctane sulfonate (PFOS), a prevalent PFAS congener, it is unknown how developmental PFOS exposure affects neuronal signaling, microglia development, and microglial-neuron communication.

OBJECTIVES

We sought to determine the extent to which PFOS exposure disrupts brain health, neuronal activity, and microglia-neuron communication during development. In addition, although PFOS impairs humoral immunity, its impact on innate immune cells, including resident microglia, is unclear. As such, we investigated whether microglia are cellular targets of PFOS, and, if so, whether disrupted microglial development or function could contribute to or is influenced by PFOS-induced neural dysfunction.

METHODS

Zebrafish were chronically exposed to either a control solution [0.1% dimethyl sulfoxide (DMSO)], 7 μ M PFOS, 14 μ M PFOS, 28 μ M PFOS, or 64 μ M perfluorooctanoic acid (PFOA). We used in vivo imaging and gene expression analysis to assess microglial populations in the developing brain and to determine shifts in the microglia state. We functionally challenged microglia state using a brain injury model and, to assess the neuronal signaling environment, performed functional neuroimaging experiments using the photoconvertible calcium indicator calcium-modulated photoactivatable ratiometric integrator (CaMPARI). These studies were paired with optogenetic manipulations of neurons and microglia, an untargeted metabolome-wide association study (MWAS), and behavioral assays.

RESULTS

Developmental PFOS exposure resulted in a shift away from the homeostatic microglia state, as determined by functional and morphological differences in exposed larvae, as well as up-regulation of the microglia activation gene p2ry12. PFOS-induced effects on microglia state exacerbated microglia responses to brain injury in the absence of increased cell death or inflammation. PFOS exposure also heightened neural activity, and optogenetic silencing of neurons or microglia independently was sufficient to normalize microglial responses to injury. An untargeted MWAS of larval brains revealed PFOS-exposed larvae had neurochemical signatures of excitatory-inhibitory imbalance. Behaviorally, PFOS-exposed larvae also exhibited anxiety-like thigmotaxis. To test whether the neuronal and microglial phenotypes were specific to PFOS, we exposed embryos to PFOA, a known immunotoxic PFAS. PFOA did not alter thigmotaxis, neuronal activity, or microglial responses, further supporting a role for neuronal activity as a critical modifier of microglial function following PFOS exposure.

DISCUSSION

Together, this study provides, to our knowledge, the first detailed account of the effects of PFOS exposure on neural cell types in the developing brain in vivo and adds neuronal hyperactivity as an important end point to assess when studying the impact of toxicant exposures on microglia function. https://doi.org/10.1289/EHP12861.

Advanced electrocatalytic redox processes for environmental remediation of halogenated organic water pollutants

Halogenated organic compounds are widespread, and decades of heavy use have resulted in global bioaccumulation and contamination of the environment, including water sources. Here, we introduce the most common halogenated organic water pollutants, their classification by type of halogen (fluorine, chlorine, or bromine), important policies and regulations, main applications, and environmental and human health risks. Remediation techniques are outlined with particular emphasis on carbon-halogen bond strengths. Aqueous advanced redox processes are discussed, highlighting mechanistic details, including electrochemical oxidations and reductions of the water-oxygen system, and thermodynamic potentials, protonation states, and lifetimes of radicals and reactive oxygen species in aqueous electrolytes at different pH conditions. The state of the art of aqueous advanced redox processes for brominated, chlorinated, and fluorinated organic compounds is presented, along with reported mechanisms for aqueous destruction of select PFAS (per- and polyfluoroalkyl substances). Future research directions for aqueous electrocatalytic destruction of organohalogens are identified, emphasizing the crucial need for developing a quantitative mechanistic understanding of degradation pathways, the improvement of analytical detection methods for organohalogens and transient species during advanced redox processes, and the development of new catalysts and processes that are globally scalable.

Examining the impact of nanoplastics and PFAS exposure on immune functions through inhibition of secretory immunoglobin A in human breast milk

Emerging contaminants such as nanoplastics (NPs) and per- and polyfluoroalkyl substances (PFAS), have been detected in the environment and breast milk, thus exposing infants to potentially harmful chemicals during breastfeeding. Breast milk contains secretory immunoglobulin A (SIgA), an antibody that plays a vital role in disease protection and the development of the infant's immune system. This study employed molecular simulation and fractional factorial designs to assess the toxicity of NPs and PFAS on breast milk and their influence on infant immunity by inhibiting SIgA. The research found that NPs and PFAS have higher binding affinities to SIgA compared to the control compound. Polycarbonate (-10.7 kcal/mol) had the highest binding affinity among plastics, while Perfluorodecanoic acid (PFDA, - 8.0 kcal/mol) had the highest binding affinity among PFAS. The relative toxic index was higher for PFAS (2.4) than for plastics (1.9), suggesting that PFAS may pose a higher overall toxicity burden on the protein. The presence of specific combinations of NPs and PFAS in breast milk may potentially harm breastfeeding infants, although additional experimental studies are required to validate these findings. These results underscore the potential risks associated with these emerging contaminants in breast milk and their impact on infant immunity.

Distribution and potential health risks of perfluoroalkyl substances (PFASs) in water, sediment, and fish in Dongjiang River Basin, Southern China

Per- and polyfluoroalkyl substances (PFASs) have attracted worldwide attention due to their high stability, refractory degradation, and bioaccumulation. The Dongjiang River is one of the most important water sources in the Pearl River Delta region. It flows from Jiangxi Province to Guangdong Province and finally into the Pearl River, providing domestic water for cities such as Guangzhou, Shenzhen, and Hong Kong. In this study, 17 PFASs in water, sediment, and fish in the Dongjiang River Basin in southern China were investigated using high-performance liquid chromatography-mass spectrometry. Total PFAS concentrations ranged from 20.83 to 372.8 ng/L in water, from 1.050 to 3.050 ng/g in sediments, and from 12.28 to 117.4 ng/g in fish. Among six species of fish, Oreochromis mossambicus (mean: 68.55 ng/g) had the highest concentration of PFASs, while Tilapia zillii (36.90 ng/g) had the lowest concentration. Perfluorooctanoic acid (PFOA) predominates in water and sediments, while perfluorooctanesulfonic acid (PFOS) predominates in fish. Long-chain perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) showed higher bioaccumulation, and the field-sourced sediment-water partition coefficients (Kd) and bioaccumulation factors (BAFs) of PFASs increased with the length of perfluorocarbon chains. PFAS concentration in the lower reaches (urban area) of the Dongjiang River is higher than that in the upper and middle reaches (rural area). The calculated hazard ratio (HR) of PFOS and PFOA levels in fish in the Dongjiang River Basin was far less than 1; hence, the potential risk to human health was limited.

The role of perfluorooctane sulfonic acid (PFOS) exposure in inflammation of intestinal tissues and intestinal carcinogenesis

PFAS (per- and polyfluoroalkyl substances) are organofluorine substances that are used commercially in products like non-stick cookware, food packaging, personal care products, fire-fighting foam, etc. These chemicals have several different subtypes made of varying numbers of carbon and fluorine atoms. PFAS substances that have longer carbon chains, such as PFOS (perfluorooctane sulfonic acid), can potentially pose a significant public health risk due to their ability to bioaccumulate and persist for long periods of time in the body and the environment. The National Academies Report suggests there is some evidence of PFOS exposure and gastrointestinal (GI) inflammation contributing to ulcerative colitis. Inflammatory bowel diseases such as ulcerative colitis are precursors to colorectal cancer. However, evidence about the association between PFOS and colorectal cancer is limited and has shown contradictory findings. This review provides an overview of population and preclinical studies on PFOS exposure and GI inflammation, metabolism, immune responses, and carcinogenesis. It also highlights some mitigation approaches to reduce the harmful effects of PFOS on GI tract and discusses the dietary strategies, such as an increase in soluble fiber intake, to reduce PFOS-induced alterations in cellular lipid metabolism. More importantly, this review demonstrates the urgent need to better understand the relationship between PFOS and GI pathology and carcinogenesis, which will enable development of better approaches for interventions in populations exposed to high levels of PFAS, and in particular to PFOS.

Fetal Glucocorticoid Mediates the Association between Prenatal Per- and Polyfluoroalkyl Substance Exposure and Neonatal Growth Index: Evidence from a Birth Cohort Study

Glucocorticoid plays a key role in the growth and organ maturation of fetus. However, the effect of glucocorticoid on the association between per- and polyfluoroalkyl substance (PFAS) exposure and fetal growth is still unknown. We detected cord cortisol (active glucocorticoid in human) and 34 PFAS concentrations in the maternal serum samples, which were collected from 202 mother-fetus pairs in the Maoming Birth Cohort from 2015 to 2018. The mediation effect of cord cortisol on the association between maternal PFAS and the neonatal growth index (NGI) was estimated. We found that higher PFAS concentrations were associated with lower NGI in terms of ponderal index, birth weight (BW), head circumference (HC), and its z-scores (BWZ and HCZ) (P < 0.05). Fetal cortisol could mediate 12.6-27.3% of the associations between PFAS and NGI. Specifically, cord cortisol mediated the association between branched perfluorooctane sulfonate (branched PFOS) and HCZ by 20.4% and between perfluorooctanoate (PFOA) and HCZ by 27.3%. Our findings provide the first epidemiological data evincing that fetal cortisol could mediate the association between prenatal PFAS exposure and fetal growth. Further investigations are recommended to elucidate the interactions among cord cortisol, PFAS, and fetal growth.

The colorimetry and smartphone determination of perfluorooctane sulfonate based on cytidine 5'-monophosphate-capped gold nanoclusters with peroxidase-like activity

Besides being a luminescent material, cytidine 5'-monophosphate-capped gold nanoclusters (AuNCs@CMP) also show superior peroxidase-like activity which can promote TMB oxidation in the presence of H₂O₂, causing the solution to turn efficiently from pale to blue. However, the presence of perfluorooctane sulfonate (PFOS) in the above system inhibited TMB oxidation and bluing of the solution, consequently establishing a colorimetric platform of AuNCs/H₂O₂/TMB for PFOS determination. The results showed that it responded to PFOS over a wide range of 2.0-50 μM, with a limit of detection (LOD) as low as 150 nM. Furthermore, in-depth mechanism investigation revealed that, rather than the active site of the catalyst being occupied by PFOS, such a hypochromatic effect originated from depletion of the reactive oxygen species (ROS) by PFOS degradation, thereby also offering a unique strategy to scavenge the lethal toxicity of PFOS. In addition, the colorimetric response of AuNCs/H₂O₂/TMB to PFOS was extended to smartphone determination conveniently based on RGB values. Finally, the established platform was applied to PFOS determination both in soil extracts and in tap water with good recovery, which supplies a novel colorimetric platform for visual determination of PFOS in practice. The method has the advantages of being rapid, sensitive and highly selective, which highlight the design and construction of more systems for determination and elimination of lethal pollutants in environmental water.

Effects of subchronic exposure of perfluorooctane sulfonate on cognitive function of mice and its mechanism

Perfluorooctane sulfonate (PFOS) is an emerging persistent organic pollutant, and its potential impact on cognitive function remains unclear. We adopted the C57BL/6J mouse model to investigate the effect of PFOS on cognitive function, as well as the underlying mechanisms. Subchronic exposure was performed by administering PFOS via drinking water for 6 months (at doses of 0, 0.2, and 2.0 mg/kg/day), starting from 10.5 months old. The object recognition ability was tested at 2, 4, and 6 months of exposure, and spatial learning and memory were assessed at endpoint. The apoptosis of neurons and astrocytes in the cortex and hippocampus was analyzed, as well as the potential apoptotic signaling pathways. Our results showed that exposure to PFOS for 6 months caused a decrease in object recognition ability and a decline in learning and spatial memory. PFOS selectively increased apoptosis in neurons of the cerebral cortex and specifically activated the endoplasmic reticulum stress PERK/CHOP signaling pathway. In conclusion, our results confirmed that subchronic exposure to PFOS can lead to cognitive impairment in mice, which might be closely associated with the specific activation of an endoplasmic reticulum stress-induced pro-apoptosis pathway in the cerebral cortex neurons.

Transcriptional investigation of the toxic mechanisms of perfluorooctane sulfonate in rats based on an RNA-Seq approach

Perfluorooctane sulfonate (PFOS) was widely used in industrial applications before it was listed as a persistent organic pollutant by the Conference of the Parties in the Stockholm Convention in 2009. Although the potential toxicity of PFOS has been studied, its toxic mechanisms remain largely undefined. Here, we investigated novel hub genes and pathways affected by PFOS to gain new conceptions of the toxic mechanisms of PFOS. Reduced body weight gain and abnormal ultra-structures in the liver and kidney tissues were spotted in PFOS-exposed rats, indicating successful establishment of the PFOS-exposed rat model. The transcriptomic alterations of blood samples upon PFOS exposure were analysed using RNA-Seq. GO analysis indicates that the differentially expressed gene-enriched GO terms are related to metabolism, cellular processes, and biological regulation. Kyoto encyclopaedia of gene and genomes (KEGG) and gene set enrichment analysis (GSEA) were conducted to identify six key pathways: spliceosome, B cell receptor signalling pathway, acute myeloid leukaemia, protein processing in the endoplasmic reticulum, NF-kappa B signalling pathway, and Fc gamma R-mediated phagocytosis. The top 10 hub genes were screened from a protein-protein interaction network and verified via quantitative real-time polymerase chain reaction. The overall pathway network and hub genes may provide new insights into the toxic mechanisms of PFOS exposure states.

Hippocampal Proteomics Reveals the Role of Glutamatergic Synapse Activation in the Depression Induced by Perfluorooctane Sulfonate

Perfluorooctane sulfonate (PFOS), a new type of persistent organic pollutant in the environment of water, has drawn significant attention in recent years due to its widespread prevalence and high toxicity. Neurotoxicity is regarded as one of the major toxic effects of PFOS, while research studies on PFOS-induced depression and the underlying mechanisms remain scarce. In this study, behavioral tests revealed the depressive-like behaviors in PFOS-exposed male mice. Neuron damages including pyknosis and staining deepening were identified through hematoxylin and eosin staining. Then, we noticed the elevation of glutamate and proline levels as well as the decline of glutamine and tryptophan levels. Proteomics analysis identified 105 differentially expressed proteins that change in a dose-dependent manner and revealed that PFOS exposure activated the glutamatergic synapse signaling pathway, which were further confirmed by Western blot, and the data were consistent with the findings of the proteomics analysis. Additionally, the downstream signaling cyclic AMP-responsive element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) and synaptic plasticity-related postsynaptic density protein 95, synaptophysin, were downregulated. Our results highlight that PFOS exposure may inhibit the synaptic plasticity of the hippocampus via glutamatergic synapse and the CREB/BDNF signaling pathway to cause depressive-like behaviors in male mice.