Perfluorooctane Sulfonate Treatment Research Articles

Lysosomal iron accumulation and subsequent lysosomes-mitochondria iron transmission mediate PFOS-induced hepatocyte ferroptosis

Perfluorooctane sulfonate (PFOS) is known as a persistent organic pollutant. A significant correlation between PFOS and liver ferroptosis has been unveiled, but the precise mechanism needs to be elucidated. In prior research, we found that PFOS treatment provoked mitochondrial iron overload. In this study, we observed a gradual increase in lysosomal iron in L-O2 cells after exposure to PFOS for 0.5–24 h. In PFOS-exposed L-O2 cells, suppressing autophagy relieved the lysosomal iron overload. Inhibiting transient receptor potential mucolipin 1 (TRPML1), a calcium efflux channel on the lysosomal membrane, led to a further rise in lysosomal iron levels and decreased mitochondrial iron overload during PFOS treatment. Suppressing VDAC1, a subtype of voltage-dependent anion-selective channels (VDACs) on the outer mitochondrial membrane, had no impact on PFOS-triggered mitochondrial iron overload, whereas restraining VDAC2/3 relieved this condition. Although silencing VDAC2 relieved PFOS-induced mitochondrial iron overload, it had no effect on PFOS-triggered lysosomal iron overload. Silencing VDAC3 alleviated PFOS-mediated mitochondrial iron overload and led to an additional increase in lysosomal iron. Therefore, we regarded VDAC3 as the specific VDACs subtype that mediated the lysosomes-mitochondria iron transfer. Additionally, in the presence of PFOS, an enhanced association between TRPML1 and VDAC3 was found in mice liver tissue and L-O2 cells. Our research unveils a novel regulatory mechanism of autophagy on the iron homeostasis and the effect of TRPML1-VDAC3 interaction on lysosomes-mitochondria iron transfer, giving an explanation of PFOS-induced ferroptosis and shedding some light on the role of classic calcium channels in iron transmission.

MPs and PFOS single and combined exposure significantly alter genetic expressions of growth hormone and insulin growth factor-related biomarkers during zebrafish embryonic development

Microplastics (MPs) and perfluorooctane sulfonate (PFOS) are emerging pollutants that are ubiquitously present in the environment and can cause series of ecotoxicological effects on aquatic animals. This study examined how the expression of genes related to insulin growth factor (igf1, igf2a, igf2b, igfra, and igfrb) and growth hormone (ghrh, gh1, ghra, and ghrb) changes during the development of zebrafish embryos exposed to 8 μm polyethylene microplastics (PE-MPs) and perfluorooctane sulfonate (PFOS) individually and in combination for 72 h. Our findings revealed that both low-concentrations of MP (50 μg/L) and PFOS (0.02 μg/L) treatments could significantly activate gene expression within a short period. High concentrations of MPs (500 μg/L) and PFOS (0.1 μg/L) not only rapidly activated gene expression but also sustained high expression levels for a longer duration. During combined exposures, peak gene expression in the low concentration groups (50 μg/L MPs and 0.02 μg/L PFOS; 50 μg/L MPs and 0.1 μg/L PFOS) primarily occurred within 12 h after treatment. In the high concentration groups (500 μg/L MPs and 0.02 μg/L PFOS), peak expression was also observed within 12 h. Notably, the combined exposure groups exhibited more pronounced effects on gene expression than the individual exposure groups. The activation of gene expression was both more significant and longer-lasting in the combined exposure, indicating a synergistic regulatory effect of MPs and PFOS. Overall, our study suggests that zebrafish embryo development can be significantly impacted by exposure to MPs, PFOS, and their combination, with combined exposures having a more lasting and profound effect on gene regulation compared to single exposures.

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.

Life in the PFAS lane: The impact of perfluoroalkyl substances on photosynthesis, cellular exudates, nutrient cycling, and composition of a marine microbial community

Perfluoroalkyl substances (PFAS) are of great ecological concern, however, exploration of their impact on bacteria-phytoplankton consortia is limited. This study employed a bioassay approach to investigate the effect of unary exposures of increasing concentrations of PFAS (perfluorooctane sulfonate (PFOS) and 6:2 fluorotelomer sulfonate (6:2 FTS)) on microbial communities from the northwestern Gulf of Mexico. Each community was examined for changes in growth and photophysiology, exudate production and shifts in community structure (16S and 18S rRNA genes). 6:2 FTS did not alter the growth or health of phytoplankton communities, as there were no changes relative to the controls (no PFOS added). On the other hand, PFOS elicited significant phototoxicity (p < 0.05), altering PSII antennae size, lowering PSII connectivity, and decreasing photosynthetic efficiency over the incubation (four days). PFOS induced a cellular protective response, indicated by significant increases (p < 0.001) in the release of transparent exopolymer particles (TEP) compared to the control. Eukaryotic communities (18S rRNA gene) changed substantially (p < 0.05) and to a greater extent than prokaryotic communities (16S rRNA gene) in PFOS treatments. Community shifts were concentration-dependent for eukaryotes, with the low treatment (5 mg/L PFOS) dominated by Coscinodiscophyceae (40 %), and the high treatment (30 mg/L PFOS) marked by a Trebouxiophyceae (50 %) dominance. Prokaryotic community shifts were not concentration dependent, as both treatment levels became depleted in Cyanobacteriia and were dominated by members of the Bacteroidia, Gammaproteobacteria, and Alphaproteobacteria classes. Further, PFOS significantly decreased (p < 0.05) the Shannon diversity and Pielou's evenness across treatments for eukaryotes, and in the low treatment (5 mg/L PFOS) for prokaryotes. These findings show that photophysiology was not impacted by 6:2 FTS but PFOS elicited toxicity that impacted photosynthesis, exudate release, and community composition. This research is crucial in understanding how PFOS impacts microbial communities.

Perfluorooctane sulfonate (PFOS) induces apoptosis and autophagy by inhibition of PI3K/AKT/mTOR pathway in human granulosa cell line KGN

Perfluorooctane sulfonate (PFOS) is recognized as an environmental endocrine disruptor with widespread use in industrial manufacturing and daily life, contributing to various public health concerns. However, the precise impacts of PFOS on the ovary and its regulatory mechanisms remain unclear. This study aims to delineate the ovarian toxicity of PFOS and scrutinize its effects on apoptosis and autophagy through modulation of the PI3K/AKT/mTOR pathway in the human granulosa cell line (KGN). Cell viability, assessed via the Cell Counting Kit-8 (CCK8), revealed a dose-dependent reduction in cell viability upon PFOS exposure. Flow cytometry analysis demonstrated an elevated proportion of apoptotic cells following PFOS treatment. Western blot analyses unveiled increased expression of Bax, Cyt c, cleaved caspase-9, and LC3-II/I, coupled with decreased expression of Bcl-2 and p62. Transmission electron microscopy (TEM) observations illustrated a heightened number of autophagosomes induced by PFOS. Molecular docking investigations, in conjunction with Western blot experiments, substantiated PFOS's significant inhibition of the PI3K/AKT/mTOR signaling pathway. These findings collectively underscore that PFOS induces apoptosis and autophagy in KGN cells through modulation of the PI3K/AKT/mTOR pathway, providing experimental evidence for PFOS-induced ovarian toxicity and elucidating the underlying regulatory mechanisms in KGN cells.

Understanding the effects of per- and polyfluoroalkyl substances on early skin development: Role of ciliogenesis inhibition and altered microtubule dynamics

Per- and polyfluoroalkyl substances (PFAS) are a class of highly stable chemicals, widely used in everyday products, and widespread in the environment, even in pregnant women. While epidemiological studies have linked prenatal exposure to PFAS with atopic dermatitis in children, little is known about their toxic effects on skin development, especially during the embryonic stage. In this study, we utilized human embryonic stem cells to generate non-neural ectoderm (NNE) cells and exposed them to six PFAS (perfluorooctanoic acid (PFOA), undecafluorohexanoic acid (PFHxA), heptafluorobutyric acid (PFBA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorobutyric acid (PFBS)) during the differentiation process to assess their toxicity to early skin development. Our results showed that PFOS altered the spindle-like morphology of NNE cells to a pebble-like morphology, and disrupted several NNE markers, including KRT16, SMYD1, and WISP1. The six PFAS had a high potential to cause hypohidrotic ectodermal dysplasia (HED) by disrupting the expression levels of HED-relevant genes. Transcriptomic analysis revealed that PFOS treatment produced the highest number (1156) of differentially expressed genes (DEGs) among the six PFAS, including the keratinocyte-related genes KRT6A, KRT17, KRT18, KRT24, KRT40, and KRT81. Additionally, we found that PFOS treatment disturbed several signaling pathways that are involved in regulating skin cell fate decisions and differentiation, including TGF-β, NOTCH, Hedgehog, and Hippo signaling pathways. Interestingly, we discovered that PFOS inhibited, by partially interfering with the expression of cytoskeleton-related genes, the ciliogenesis of NNE cells, which is crucial for the intercellular transduction of the above-mentioned signaling pathways. Overall, our study suggests that PFAS can inhibit ciliogenesis and hamper the transduction of important signaling pathways, leading potential congenital skin diseases. It sheds light on the underlying mechanisms of early embryonic skin developmental toxicity and provides an explanation for the epidemiological data on PFAS. Environmental implicationWe employed a model based on human embryonic stem cells to demonstrate that PFOS has the potential to elevate the risk of hypohidrotic ectodermal dysplasia. This is achieved by targeting cilia, inhibiting ciliogenesis, and subsequently disrupting crucial signaling pathways like TGF-β, NOTCH, Hedgehog, and Hippo, during the early phases of embryonic skin development. Our study highlights the dangers and potential impacts of six PFAS pollutants on human skin development. Additionally, we emphasize the importance of closely considering PFHxA, PFBA, PFHxS, and PFBS, as they have shown the capacity to modify gene expression levels, albeit to a lesser degree.

Efflux transport proteins of Tetrahymena thermophila play important roles in resistance to perfluorooctane sulfonate exposure

The biotoxicity of perfluorooctane sulfonate (PFOS) has been a concern. However, the effects of PFOS on Tetrahymena thermophila, a unicellular model organism, remain unclear. This study aimed to investigate the toxicity and detoxification mechanism of PFOS in this protozoan. PFOS did not show prominent toxic effects on T. thermophila. Cell viability of T. thermophila can be concentration-dependently increased by PFOS. PFOS also increased the stability of cell membranes and the activity of lysosomes. However, PFOS inhibited efflux transporter activities. Most of the PFOS amount remained in the culture medium during the culture periods. Only a low amount of PFOS was absorbed by cells, where PFOS molecules were mainly combined with membrane proteins. The expressions of four membrane protein genes involved in transporting xenobiotics were analyzed by real time-PCR. The gene abcg25 was significantly up-regulated. The growth of abcg25 gene knockout protozoans under PFOS treatment was slightly inhibited. However, the amount of PFOS adsorbed by the knockout protozoans showed no significant difference from the Wild-type protozoans. We concluded that the ABCG25 protein might play a key role in preventing PFOS from entering the cell or being exported from the cells to protect T. thermophila against PFOS. However, ABCG25 was not the only membrane protein able to bind with PFOS.

Bile acid metabolism disorder mediates hepatotoxicity of Nafion by-product 2 and perfluorooctane sulfonate in male PPARα-KO mice

Perfluorooctane sulfonate (PFOS) and Nafion by-product 2 (H-PFMO2OSA) induce hepatotoxicity in male mice via activation of the peroxisome proliferator-activated receptor α (PPARα) pathway; however, accumulating evidence suggests that PPARα-independent pathways also play a vital role in hepatotoxicity after exposure to per- and polyfluoroalkyl substances (PFASs). Thus, to assess the hepatotoxicity of PFOS and H-PFMO2OSA more comprehensively, adult male wild-type (WT) and PPARα knockout (PPARα-KO) mice were exposed to PFOS and H-PFMO2OSA (1 or 5 mg/kg/d) for 28 d via oral gavage. Results showed that although elevations in alanine transaminase (ALT) and aspartate aminotransferase (AST) were alleviated in PPARα-KO mice, liver injury, including liver enlargement and necrosis, was still observed after PFOS and H-PFMO2OSA exposure. Liver transcriptome analysis identified fewer differentially expressed genes (DEGs) in the PPARα-KO mice than in the WT mice, but more DEGs associated with the bile acid secretion pathway after PFOS and H-PFMO2OSA treatment. Total bile acid content in the liver was increased in the 1 and 5 mg/kg/d PFOS-exposed and 5 mg/kg/d H-PFMO2OSA-exposed PPARα-KO mice. Furthermore, in PPARα-KO mice, proteins showing changes in transcription and translation levels after PFOS and H-PFMO2OSA exposure were involved in the synthesis, transportation, reabsorption, and excretion of bile acids. Thus, exposure to PFOS and H-PFMO2OSA in male PPARα-KO mice may disturb bile acid metabolism, which is not under the control of PPARα.

Mitochondrial iron overload mediated by cooperative transfer of plasma membrane ATP5B and TFR2 to mitochondria triggers hepatic insulin resistance under PFOS exposure

In general populations, insulin resistance (IR) is related to perfluorooctane sulfonate (PFOS), a persistent organic pollutant. However, the underlying mechanism remains unclear. In this study, PFOS induced mitochondrial iron accumulation in the liver of mice and human hepatocytes L-O2. In the PFOS-treated L-O2 cells, mitochondrial iron overload preceded the occurrence of IR, and pharmacological inhibition of mitochondrial iron relieved PFOS-caused IR. Both transferrin receptor 2 (TFR2) and ATP synthase β subunit (ATP5B) were redistributed from the plasma membrane to mitochondria with PFOS treatment. Inhibiting the translocation of TFR2 to mitochondria reversed PFOS-induced mitochondrial iron overload and IR. In the PFOS-treated cells, ATP5B interacted with TFR2. Stabilizing ATP5B on the plasma membrane or knockdown of ATP5B disturbed the translocation of TFR2. PFOS inhibited the activity of plasma-membrane ATP synthase (ectopic ATP synthase, e-ATPS), and activating e-ATPS prevented the translocation of ATP5B and TFR2. Consistently, PFOS induced ATP5B/TFR2 interaction and redistribution of ATP5B and TFR2 to mitochondria in the liver of mice. Thus, our results indicated that mitochondrial iron overload induced by collaborative translocation of ATP5B and TFR2 was an up-stream and initiating event for PFOS-related hepatic IR, providing novel understandings of the biological function of e-ATPS, the regulatory mechanism for mitochondrial iron and the mechanism underlying PFOS toxicity.

Whole-Genome Transcriptome Profiling in PFOS-treated Uterine Artery Endothelial Cells Isolated from Pregnant Women.

Empirical evidence from human studies has demonstrated a correlative relationship between perfluorooctane sulfonate (PFOS) exposure and increased risks of preeclampsia and fetal developmental complications. Although experimental and circumstantial data suggest that PFOS induces endothelial dysfunction, leading to decreased uterine arterial blood flow and gestational hypertension, the precise regulatory mechanisms responsible for this effect remain unknown. To address this issue, we treated human uterine artery endothelial cells (hUAECs) isolated from pregnant women with 10 μmol/L PFOS or vehicle and conducted comparative transcriptomic analyses. We identified a total of 19 differentially expressed genes, 9 of which were upregulated and 10 were down-regulated in PFOS-treated pregnant hUAECs. Pre-ranked gene set enrichment analysis unveiled a distinct set of activated genes involved in osmotic stress, cellular stress response, translation regulation, metabolic regulation, and oxidation-reduction processes in PFOS-treated pregnant hUAECs. Furthermore, PFOS treatment resulted in the downregulation of genes implicated in cardiac muscle cell proliferation, embryonic morphogenesis, and muscle cell proliferation. In addition, we observed differential splicing events in 2678 genes in hUAECs exposed to PFOS, with cross-comparison analysis revealing 4 genes that were both differentially expressed and alternatively spliced and were implicated in oxidative stress and cardiac development. In conclusion, this study provides a comprehensive understanding of the molecular mechanisms underlying PFOS-induced gestational uterine artery endothelial dysfunction during pregnancy, offering a valuable resource for future research in this field.

Perfluorooctane sulfonate promotes hepatic lipid accumulation and steatosis in high-fat diet mice through AMP-activated protein kinase/acetyl-CoA carboxylase (AMPK/ACC)pathway.

Perfluorooctane sulfonate (PFOS) is a hepatotoxic environmental organic pollutant that can cause aberrant lipid accumulation in the liver. However, the molecular mechanism underlying PFOS-induced hepatic steatosis remains unclear. Our research showed that subchronic PFOS exposure inhibited AMP-activated protein kinase (AMPK) phosphorylation, leading to increased acetyl-CoA carboxylase (ACC) activity, attenuated fatty acid β-oxidation, and consequent liver lipid accumulation. We found that 1 mg/kg/day PFOS exposure significantly aggravated steatosis in high-fat diet (HFD)-fed mice, along with reduced AMPK activity. Oil Red O results showed that PFOS exposure caused fat accumulation in HepG2 cells. As predicted, PFOS treatment reduced the level of phosphorylated AMPK in a concentration-dependent manner, leading to subsequent increase in ACC activity and lipid droplet accumulation in HepG2 cells. Treatment with 200-μM AMPK agonist AICAR alleviated PFOS-induced ACC activation and lipid accumulation. In summary, our data highlight a crucial role of AMPK/ACC pathway in PFOS-mediated liver lipid metabolic disorders.

Oxidative stress and Cx43-mediated apoptosis are involved in PFOS-induced nephrotoxicity

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant that can cause nephrotoxicity. However, the underlying mechanisms are not fully understood and require further investigation. In the present study, we established a PFOS-exposed Sprague-Dawley (SD) rat kidney injury model by intraperitoneal injection of PFOS (1 mg/kg and 10 mg/kg body weight) every alternate day for 15 days and cytotoxicity models of normal rat kidney epithelial (NRK52E) and human renal proximal tubular (HK2) cells exposed to PFOS (20 μM and 60 μM) for 24 h to reveal the mechanisms underlying PFOS-induced nephrotoxicity. Data showed that PFOS increased the kidney index and induced nephrotoxicity in rats. Furthermore, PFOS significantly increased malondialdehyde (MDA) levels, decreased GSH peroxidase (GSH-PX) activity in kidney tissues, and increased intracellular reactive oxygen species (ROS) levels in NRK52E and HK2 cells. Following PFOS treatment, mitochondrial damage in the renal tubular epithelial cells of rats was observed and the mitochondrial membrane potential (ΔΨm) was decreased in NRK52E cells. PFOS upregulated apoptosis of tubular epithelial cells and expression of Connexin 43 (Cx43) in vitro and in vivo. The Cx43 inhibitor gap26 attenuated the apoptosis of tubular epithelial cells. In conclusion, our findings reveal that PFOS may trigger renal tubular cell apoptosis through oxidative stress and upregulation of Cx43, resulting in PFOS-induced nephrotoxicity.

SARS‐CoV‐2 Spike Protein Enhances Toxicant‐Induced Blood‐Brain Barrier Dysfunction

Exposure to toxicants such as benzo(a)pyrene (BaP), 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD), or perfluorooctane sulfonate (PFOS), or viruses such as severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is associated with neuropathology and blood‐brain barrier (BBB) dysfunction. Recently, toxicant exposure has been reported to result in poorer health outcomes of (SARS‐CoV‐2) infection. Thus, we hypothesized that co‐exposure to toxicants and SARS‐CoV‐2 will cause greater BBB disruption than exposure to toxicants or SARS‐CoV‐2 alone.BBB permeability was assessed in vitro by measuring transendothelial electrical resistance (TEER; ohms cm2) of a monolayer of primary adult human brain microvascular endothelial cells (hBMECs). Cells were allowed to form a confluent monolayer on a 96‐well plate outfitted with circuit electrodes. Cells were treated with BaP (2, 10, and 50 uM), TCDD (1.5, 15, and 150 nM), PFOS (3, 30, and 300 uM), or recombinant SARS‐CoV‐2 spike protein (SP; 0.1, 1, and 10 nM). In experiments to test the synergistic effects of toxicants and SP, cells were treated with toxicants, then immediately were treated with SP (10 nM). Cell viability was assessed 24 hours after treatment using Cell Proliferation Kit I (Roche Diagnostics, Inc). Gene expression of tight junction protein 1 (TJP1) and vascular cell adhesion molecule‐1 (VCAM‐1) was measured by RT‐qPCR. One‐ and two‐way ANOVA followed by Holm‐Sidak post‐hoc comparisons were performed to detect differences in TEER (resistance, ohms cm2) and cell viability (absorbance, nm). T‐tests were performed to compare RT‐qPCR data. Statistical significance was reached at p < 0.05. Technical triplicates were averaged on 4 different days to obtain N = 4/group.Recombinant SARS‐CoV‐2 spike protein did not significantly affect the resistance or leakiness of the monolayer of hBMECs at any of the concentrations tested. However, when hBMECs were treated with SP (10 nM) in conjunction with BaP or PFOS, TEER was significantly reduced beyond treatment with the toxicants alone. When compared to BaP treatment alone, SP significantly lowered TEER in hBMECs treated with 10 uM or 50 uM of BaP at 9 to 24 hours after treatment (Holm‐Sidak, t’s > 2.507, p’s < 0.04), indicating a synergistic effect of SP and BaP in increasing leakiness of the hBMEC barrier. Similarly, SP caused a significant reduction in TEER of hBMECs treated with 3 uM PFOS starting at 15 hours post treatment when compared to PFOS treatment alone (Holm‐Sidak, t’s > 2.273, p’s < 0.04). TEER of TCDD‐treated hBMECs were not affected by SP treatment. At 24 hours after treatment, cell viability and expression of VCAM‐1 and TJP1 were not altered by treatment by SP alone, nor did SP affect cell viability or gene expression of toxicant‐treated hBMECs. These results suggest that disruption of the hBMEC monolayer was not due to cell death, or expression levels of VCAM‐1 and TJP1.To our knowledge, this is the first report of the synergistic effects of SARS‐CoV‐2 spike protein and environmental toxicants in an in vitro model of the BBB. These findings suggest that individuals who are exposed to environmental pollutants may suffer greater damage of their BBB if subsequently exposed to SARS‐CoV‐2 spike proteins or SARS‐CoV‐2.

Effects of Toxicants on Blood‐Brain Barrier Function in Resilient Versus Non‐resilient Mice

Environmental toxicants such as perfluorooctane sulfonate (PFOS), benzo‐a‐pyrene (BaP) and 2, 3, 7, 8‐tetrachlorodibenzo‐p‐dioxin (TCDD) can damage brain microvascular endothelial cells (BMECs), the primary component of the blood‐brain barrier (BBB). It is largely unknown whether differences in BBB phenotype contribute to people’s susceptibility to the neurological effects of environmental toxicants. We used a mouse model of psychological resilience to investigate effects of environmental toxicants on BBB function. In this model, C57BL/6 and Balb/c mice display “resilient” and “non‐resilient” phenotypes, respectively. We hypothesized that BaP, TCDD, and PFOS will affect BMECs of C57BL/6 mice differently than the BMECs of the Balb/c mice.BBB permeability was assessed by measuring transendothelial electrical resistance (TEER; ohms cm2) of primary adult mouse BMECs derived from C57BL/6 (cBMECs) or Balb/c (bBMECs) mice. Cells were treated with BaP (2, 10, 50 uM), TCDD (1.5, 15, 150 nM), PFOS (3, 30, 300 uM). After 24 hours, gene expression of occludin (Ocln), tight junction protein‐1 (Tjp‐1), claudin‐5 (Cldn‐5), and vascular cell adhesion molecule 1 (Vcam‐1) was measured by RT‐qPCR. Tetrazolium salt assay was used to measure cell viability. One‐ and two‐way ANOVA followed by Holm‐Sidak post‐hoc tests were performed to detect differences in TEER and cell viability (absorbance, nm). T‐tests were performed to compare RT‐qPCR data. Statistical significance was reached at p&lt;0.05. Experiments were performed with technical triplicates on 3 different days to obtain N=3/group.cBMECs displayed higher maximal TEER than bBMECs (1194±149 versus 628±64 ohms cm2; p&lt;0.01), and were significantly more sensitive to the TEER‐reducing effects of BaP (10 and 50 uM) after 1 hour of exposure (Holm‐Sidak, t’s&gt;5.24, p’s&lt;0.0002). This difference was maintained for 24 hours after treatment. After 1 hour of PFOS treatment (3 and 300 uM), TEER of bBMECs was significantly lower than that of the cBMECs (Holm‐Sidak, t’s&gt;3.173, p’s&lt;0.017). However, there was no difference in TEER between cell types at any other PFOS concentrations or time points. TCDD treatment induced a significant increase in TEER in both cBMECs and bBMECs over the course of 24 hours (ANOVA, p’s&lt;0.02), with no significant difference in TEER response to treatment between cell types. Although cell viability was higher in bBMECs, treatment with BaP, PFOS or TCDD did not differentially affect viability of the two cell types after 24 hours. Gene expression of Ocln, Cldn‐5, and Vcam‐1 were reduced only by the highest concentration of PFOS in both cell types (p’s&lt;0.04), while Tjp‐1 expression was not affected by any of the treatments across both cell types.Our study demonstrates that the BBB’s response to toxicants is dependent on the phenotype (resilient versus non‐resilient) of the individual, and that the difference in direction and magnitude of the response is toxicant‐specific. This suggests that the variability in BBB phenotype associated with psychological resilience may determine an individual’s susceptibility to the effects of environmental toxicants.

Exploring key reaction sites and deep degradation mechanism of perfluorooctane sulfonate via peroxymonosulfate activation under electrocoagulation process

Perfluorooctane sulfonate (PFOS), normally present in groundwater and surface water, is an emerging environmental contaminants, but is extremely difficult to be degraded due to high energy of the C-F bond. Here, an electrocoagulation (EC) technique coupled with peroxymonosulfate (PMS) activation was used to deeply degrade PFOS. Results showed that approximately 100% PFOS was removed from the solution in the monopolar serial (MS) mode within 60 min and achieved a high kinetic rate of 0.074 min−1, which was significantly higher than those of reported studies (Table S3). Energy consumption (2.06 kWh/kg) in the MS mode was significantly lower than that of Al (52.30 kWh/kg) and Zn (213.50 kWh/kg) electrodes, which further confirmed the potential application prospects of EC technique. The quenching experiments, electron spin response (ESR) analysis, and DFT calculations can verify that ·OH was the main radical from the reaction of Fe2+–OH reaction site with PMS. In addition, results from fluorine balance and TOC removal also indicated the complete mineralization and degradation of PFOS in the EC process. Quantum chemical calculations can confirm the PFOS degradation mechanism and key active sites for direct electron transfer and radical attack. After five cycle operations of PFOS degradation, the EC process was still effective in degrading PFOS with a removal efficiency above 98%. Thus, this work provided a novel alternative for the high-effective treatment of PFOS from contaminated environmental water bodies.

Perfluorooctane sulfonate (PFOS) triggers migration and invasion of esophageal squamous cell carcinoma cells via regulation of Zeb1

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent and deadly cancers worldwide, especially in Eastern Asia. As a potential endocrine-disrupting chemical (EDC), perfluorooctane sulfonate (PFOS) can mimic estrogen, disturb the estrogen signals, and then cause various diseases. Although ESCC can be directly exposed to PFOS during food digestion, the effects and mechanisms of PFOS on the development of ESCC are still not well illustrated. This study showed that PFOS can promote the migration and invasion of ESCC cells. Further, PFOS treatment can increase the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9, while decreasing the expression of E-Cadherin (E-Cad). Zeb1, an important transcription factor for cell motility, was essential for PFOS induced migration and invasion of ESCC cells. PFOS can increase the expression of Zeb1 via upregulation of its transcription and proteins stability. A-kinase interacting protein 1 (AKIP1) and ataxia-telangiectasia mutated (ATM) were responsible for PFOS induced transcription and proteins stability of Zeb1 in ESCC cells, respectively. Collectively, our data indicated that environmental exposure and body accumulation of PFOS might be an important risk factor for ESCC progression.

Characterization of PFOS toxicity on in-vivo and ex-vivo mouse pancreatic islets

Considerable human data have shown that the exposure to perfluorooctane sulfonate (PFOS) correlates to the risk of metabolic diseases, however the underlying effects are not clearly elucidated. In this study, we investigated the impacts of PFOS treatment, using in-vivo, ex-vivo and in-vitro approaches, on pancreatic β-cell functions. Mice were oral-gavage with 1 and 5 μg PFOS/g body weight/day for 21 days. The animals showed a significant increase in liver triglycerides, accompanied by a reduction of triglycerides in blood sera and glycogen in livers and muscles. Histological examination of pancreases showed no noticeable changes in the size and number of islets from the control and treatment groups. Immunohistochemistry showed a reduction of staining intensities of insulin and the transcriptional factors (Pdx-1, islet-1) in islets of pancreatic sections from PFOS-treated groups, but no changes in the intensity of Glut2 and glucagon were noted. Transcriptomic study of isolated pancreatic islets treated ex vivo with 1 μM and 10 μM PFOS for 24 h, underlined perturbations of the insulin signaling pathways. Western blot analysis of ex-vivo PFOS-treated islets revealed a significant reduction in the expression levels of the insulin receptor, the IGF1 receptor-β, Pdk1-Akt-mTOR pathways, and Pdx-1. Using the mouse β-cells (Min-6) treated with 1 μM and 10 μM PFOS for 24 h, Western blot analysis consistently showed the PFOS-treatment inhibited Akt-pathway and reduced cellular insulin contents. Moreover, functional studies revealed the inhibitory effects of PFOS on glucose-stimulated insulin-secretion (GSIS) and the rate of ATP production. Our data support the perturbing effects of PFOS on animal metabolism and demonstrate the underlying molecular targets to impair β-cell functions.

Perfluorooctane sulfonate continual exposure impairs glucose-stimulated insulin secretion via SIRT1-induced upregulation of UCP2 expression.

Per- and polyfluoroalkyl substances (PFASs) are environmentally and biologically persistent anthropogenic chemicals linked to adverse health outcomes. Epidemiological data have revealed association between exposure to specific PFAS and disruption of insulin level in bodies. However, the effect of PFASs on insulin secretion and the responsible molecular mechanism are poorly understood. In the present study, we used perfluorooctane sulfonate (PFOS) as a representative PFAS family member to investigate its effect on the insulin secretion in mouse pancreatic β cells (β-TC-6). Our results showed that exposure to PFOS inhibited silent information regulator 1 (SIRT1) activity, and molecular simulation showed PFOS could fit into the pocket overlapped with the nicotinamide adenine dinucleotide (NAD+) binding cavity in SIRT1. PFOS exposure upregulated uncoupling protein 2 (UCP2) expression, and this upregulation was blunted in the presence of Ex-527, a SIRT1 specific inhibitor. The mitochondria membrane potential (ΔΨm), as well as the glucose-induced ATP production and Ca2+ influx decreased under PFOS treatment. PFOS continual exposure (48h) impaired glucose stimulated insulin secretion (GSIS), while the gene expression of insulin was not significantly altered. Importantly, the SIRT1 activator and UCP2 inhibitor could partly reverse the PFOS-induced impairment of GSIS. Taken together, the results suggested that PFOS continual exposure could inhibit SIRT1 activity, and the SIRT1-UCP2 pathway mediated, at least partially, the PFOS induced GSIS impairment.

Perfluorooctane sulfonate induces autophagy-associated apoptosis through oxidative stress and the activation of extracellular signal-regulated kinases in renal tubular cells.

Perfluorooctane sulfonate (PFOS) is among the most abundant organic pollutants and is widely distributed in the environment, wildlife, and humans. Its toxic effects and biological hazards are associated with its long elimination half-life in humans. However, how it affects renal tubular cells (RTCs) remains unclear. In this study, PFOS was observed to mediate the increase in reactive oxygen species (ROS) generation, followed by the activation of the extracellular-signal-regulated kinase 1/2 (ERK1/2) pathway, which induced autophagy in RTCs. Although PFOS treatment induced autophagy after 6 h, prolonged treatment (24 h) reduced the autophagic flux by increasing lysosomal membrane permeability (LMP), leading to increased p62 protein accumulation and subsequent apoptosis. The increase in LMP was visualized through increased green fluorescence with acridine orange staining, and this was attenuated by 3-methyladenine, an autophagy inhibitor. N-acetyl cysteine and an inhibitor of the mitogen-activated protein kinase kinases (U0126) attenuated autophagy and apoptosis. Taken together, these results indicate that ROS activation and ROS-mediated phosphorylated ERK1/2 activation are essential to activate autophagy, resulting in the apoptosis of PFOS-treated RTCs. Our findings provide insight into the mechanism of PFOS-mediated renal toxicity.

Effects of gestational exposure to perfluorooctane sulfonate on the lung development of offspring rats.

Perfluorooctane sulfonate (PFOS) is a man-made fluorosurfactant widely used in industry and consumer products. Previous studies with rats suggested that gestational exposure to PFOS may affect the lung development in the offspring. The mechanism, however, is still unknown. In the present study, we have exposed 24 pregnant SD rats from gestational day 12-18 to different doses of PFOS (0, 1 or 5mg/kg BW/day). The lungs of the offspring were analyzed at postnatal days 1, 3, 7 and 14. PFOS treatment appeared to reduce the alveolar numbers, resulting in simplified alveolar structure and thickened alveolar septa. Also, PFOS treated animals had increased lung inflammation with up-regulated inflammasome associated proteins NLRP3, ASC, Caspase-1 and GSDMD and increased inflammatory cytokines IL-18 and IL-1β. At the same time, HIF-1α and VEGFA were significantly down-regulated. Since HIF-1α and VEGFA are critical factors promoting alveolar development and pulmonary angiogenesis, these results suggested that PFOS may also affect lung development by inhibiting HIF-1α and VEGFA expression. Our results here indicate that gestational exposure to PFOS may affect lung development in the offspring with pathological characteristics similar to bronchopulmonary dysplasia (BPD), a severe lung developmental defect. The results also suggest that environmental factors such as PFOS may contribute to the increasing incidence of developmental lung diseases, such as BPD, by elevating lung inflammation and inhibiting lung development.