PFOS prenatal exposure induce mitochondrial injury and gene expression change in hearts of weaned SD rats

Single-cell RNA sequencing reveals the role of mitochondrial dysfunction in the cardiogenic toxicity of perfluorooctane sulfonate in human embryonic stem cells

Perfluorooctane sulfonate (PFOS), an endocrine-disrupting chemical pollutant, affects embryonic heart development; however, the mechanisms underlying its toxicity have not been fully elucidated. Here, Single-cell RNA sequencing (scRNA-seq) was used to investigate the overall effects of PFOS on myocardial differentiation from human embryonic stem cells (hESCs). Additionally, apoptosis, mitochondrial membrane potential, and ATP assays were performed. Downregulated cardiogenesis-related genes and inhibited cardiac differentiation were observed after PFOS exposure in vitro. The percentages of cardiomyocyte and cardiac progenitor cell clusters decreased significantly following exposure to PFOS, while the proportion of primitive endoderm cell was increased in PFOS group. Moreover, PFOS inhibited myocardial differentiation and blocked cellular development at the early- and middle-stage. A Gene Ontology analysis and pseudo-time trajectory illustrated that PFOS disturbed multiple processes related to cardiogenesis and oxidative phosphorylation in the mitochondria. Furthermore, PFOS decreased mitochondrial membrane potential and induced apoptosis. These results offer meaningful insights into the cardiogenic toxicity of PFOS exposure during heart formation as well as the adverse effects of PFOS on mitochondria.

Environmental pollutant pre- and polyfluoroalkyl substances are associated with electrocardiogram parameters disorder in adults

Environmental pollutants exposure might disrupt cardiac function, but evidence about the associations of per- and polyfluoroalkyl substances (PFASs) exposure and cardiac conduction system remains sparse. To explore the associations between serum PFASs exposure and electrocardiogram (ECG) parameters changes in adults, we recruited 1229 participants (mean age: 55.1 years) from communities of Guangzhou, China. 13 serum PFASs with detection rate > 85% were analyzed finally. We selected 6 ECG parameters [heart rate (HR), PR interval, QRS duration, Bazett heart rate-corrected QT interval (QTc), QRS electric axis and RV5 + SV1 voltage] as outcomes. Generalized linear models (GLMs) and Bayesian kernel machine regression (BKMR) model were conducted to explore the associations of individual and joint PFASs exposure and ECG parameters changes, respectively. We detected significant associations of PFASs exposure with decreased HR, QRS duration, but with increased PR interval. For example, at the 95th percentile of 6:2 Cl-PFESA, HR and QRS duration were - 6.98 [95% confidence interval (CI): - 9.07, - 4.90] and - 6.54(95% CI: -9.05, -4.03) lower, but PR interval was 7.35 (95% CI: 3.52, 11.17) longer than those at the 25th percentile. Similarly, significant joint associations were observed in HR, PR interval and QRS duration when analyzed by BKMR model.

A review of cardiovascular effects and underlying mechanisms of legacy and emerging per- and polyfluoroalkyl substances (PFAS)

Cardiovascular disease (CVD) poses the leading threats to human health and life, and their occurrence and severity are associated with exposure to environmental pollutants. Per- and polyfluoroalkyl substances (PFAS), a group of widely used industrial chemicals, are characterized by persistence, long-distance migration, bioaccumulation, and toxicity. Some PFAS, particularly perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexanesulfonic acid (PFHxS), have been banned, leaving only legacy exposure to the environment and human body, while a number of novel PFAS alternatives have emerged and raised concerns, such as polyfluoroalkyl ether sulfonic and carboxylic acid (PFESA and PFECA) and sodium p-perfluorous nonenoxybenzene sulfonate (OBS). Overall, this review systematically elucidated the adverse cardiovascular (CV) effects of legacy and emerging PFAS, emphasized the dose/concentration-dependent, time-dependent, carbon chain length-dependent, sex-specific, and coexposure effects, and discussed the underlying mechanisms and possible prevention and treatment. Extensive epidemiological and laboratory evidence suggests that accumulated serum levels of legacy PFAS possibly contribute to an increased risk of CVD and its subclinical course, such as cardiac toxicity, vascular disorder, hypertension, and dyslipidemia. The underlying biological mechanisms may include oxidative stress, signaling pathway disturbance, lipid metabolism disturbance, and so on. Various emerging alternatives to PFAS also play increasingly prominent toxic roles in CV outcomes that are milder, similar to, or more severe than legacy PFAS. Future research is recommended to conduct more in-depth CV toxicity assessments of legacy and emerging PFAS and explore more effective surveillance, prevention, and treatment strategies, accordingly.

PFOS disrupts key developmental pathways during hiPSC-derived cardiomyocyte differentiation in vitro

Exposure to perfluorooctanesulfonic acid (PFOS) has been associated with congenital heart disease (CHD) and decreased birth weight. PFOS exposure can disrupt signaling pathways relevant for cardiac development in stem cell-derived cardiomyocyte assays, such as the PluriBeat assay, where spheroids of human induced pluripotent stem cells (hiPSCs) differentiate into contracting cardiomyocytes. Notably, cell line origin can also affect how the assay responds to chemical exposure. Herein, we examined the effect of PFOS on cardiomyocyte differentiation by transcriptomics profiling of two different hiPSC lines to see if they exhibit a common pattern of disruption. Two stages of differentiation were investigated: the cardiac progenitor stage and the cardiomyocyte stage. Many differentially expressed genes (DEGs) were observed between cell lines independent of exposure. However, 135 DEGs were identified as common between the two cell lines. Of these, 10 DEGs were associated with GO-terms related to the heart. PFOS exposure disrupted multiple signaling pathways relevant to cardiac development, including WNT, TGF, HH, and EGF. Of these pathways, genes related to the non-canonical WNTCa²⁺ signaling was particularly affected. PFOS thus has the capacity to disrupt pathways important for cardiac development and function.

Perfluorooctane sulfonate induces heart toxicity involving cardiac apoptosis and inflammation in rats

Perfluorooctane sulfonate (PFOS) is a persistent pollutant that exerts toxicity and induces cardiogenesis in humans and animals. Yet, the effect of PFOS exposure on cardiac toxicity in adult rats has, to our knowledge, not been reported and the mechanism still remains unknown. The present study aimed to investigate the toxicity of PFOS on rat hearts and any associated mechanisms. Rats were exposed to 0 (control), 1 and 10 mg/kg PFOS every other day for 14 days. Body weight and heart weight were recorded. The serum levels of lactic dehydrogenase (LDH), creatine kinase (CK), creatine kinase-isoenzyme-MB (CK-MB) and cardiac troponin-T (cTn-T) in heart tissues were measured using biochemical assays. TUNEL staining and western blotting were applied to analyze levels of apoptosis in rat hearts. Pathological assessment and immunohistochemistry analysis of heart tissues were used to evaluate the levels of PFOS-induced cardiotoxicity and inflammatory infiltration. PFOS exposure at the dosage of 10 mg/kg significantly increased the percentage of heart to body weight; however, it did not alter the body weight. At 10 mg/kg, PFOS significantly increased expression levels of myocardial injury markers, such as cTn-T, LDH, CK and CK-MB, while 1 mg/kg PFOS upregulated the expression level of cTn-T in rats. Notably, cardiac fibrosis and myocardiac hypertrophy appeared in the 10 mg/kg PFOS group. In addition, TUNEL-positive cells were significantly increased by exposure to 10 mg/kg PFOS in rat heart tissues. The protein expressions profiles of p53 and Bax were also significantly upregulated in the 10 mg/kg PFOS group. Inflammatory infiltration, detected by anaylzing expression levels of IL-1β and TNF-α, was significantly raised by 10 mg/kg PFOS exposure. In conclusion, these results demonstrated that 10 mg/kg PFOS-induced cardiac toxicity in rats, which was associated with an increase in apoptosis and the expression of proinflammatory cytokines.

Perfluorooctane sulfonate (PFOS) exposure of bovine oocytes affects early embryonic development at human-relevant levels in an in vitro model

Perfluorooctane sulfonate (PFOS) has been added to Stockholm Convention for global phase out, but will continue to contribute to the chemical burden in humans for a long time to come due to extreme persistence in the environment. In the body, PFOS is transferred into to the ovarian follicular fluid that surrounds the maturing oocyte. In the present study, bovine cumulus oocyte complexes were exposed to PFOS during 22 h in vitro maturation. Concentrations of 2 ng g^-1 (PFOS-02) representing average human exposure and 53 ng g^-1 (PFOS-53) relevant to highly exposed groups were used. After exposure, developmental competence was recorded until day 8 after fertilisation. Blastocysts were fixed and either stained to evaluate blastomere number and lipid distribution using confocal microscopy or frozen and pooled for microarray-based gene expression and DNA methylation analyses. PFOS-53 delayed the first cleavage to two-cell stage and beyond at 44 h after fertilisation (p < .01). No reduction of proportion blastocysts were seen at day 8 in either of the groups, but PFOS-53 exposure resulted in delayed development into more advanced stages of blastocysts seen as both reduced developmental stage (p = .001) and reduced number of blastomeres (p = .04). Blastocysts showed an altered lipid distribution that was more pronounced after exposure to PFOS-53 (increased total lipid volume, p=.0003, lipid volume/cell p < .0001) than PFOS-02, where only decreased average lipid droplet size (p=.02) was observed. Gene expression analyses revealed pathways differently regulated in the PFOS-treated groups compared to the controls, which were related to cell death and survival through e.g., P38 mitogen-activated protein kinases and signal transducer and activator of transcription 3, which in turn activates tumour protein 53 (TP53). Transcriptomic changes were also associated with metabolic stress response, differentiation and proliferation, which could help to explain the phenotypic changes seen in the blastocysts. The gene expression changes were more pronounced after exposure to PFOS-53 compared to PFOS-02. DNA-methylation changes were associated with similar biological functions as the transcriptomic data, with the most significantly associated pathway being TP53. Collectively, these results reveal that brief PFOS exposure during oocyte maturation alters the early embryo development at concentrations relevant to humans. This study adds to the evidence that PFOS has the potential to affect female fertility.

Per- and Polyfluoroalkyl Substances (PFAS): Significance and Considerations within the Regulatory Framework of the USA

Per- and polyfluoroalkyl substances (PFAS) are an emerging environmental crisis. Deemed forever chemicals, many congeners bioaccumulate and are incredibly persistent in the environment due to the presence of the strong carbon-fluorine covalent bonds. Notable PFAS compounds include perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and GenX. Robust toxicological knowledge exists for these substances, but regulatory decisions based on this knowledge has fallen behind. The United States Environmental Protection Agency (EPA) has addressed this issue with the PFAS Action Plan and EPA Council on PFAS, but the regulatory framework is severely lacking. Currently, no federal regulations or standards exist. Many occupational and non-occupational human cohorts exist that can lend knowledge on the environmental implications of PFAS and associated health effects. Occupationally, firefighters face significant exposure risks due to use of PFAS containing aqueous film-forming foams (AFFFs) and personal protective equipment contamination. Non-occupationally, wastewater discharge in North Carolina led to chronic and widespread residential exposure to GenX via drinking water contamination. This public health review seeks to convey the current and future significance of PFAS as an environmental contaminate, to lend considerations on regulatory frameworks within the USA, and to help guide and promote the need for future epidemiological studies in order to tackle this environmental emergency. While the PFAS Action Plan creates a scientific and regulatory foundation, it is important to take these lessons and apply them to future environmental health issues.

Developmental effects of PFOS, PFOA and GenX in a 3D human induced pluripotent stem cell differentiation model

Polyfluoroalkyl substances (PFASs), including perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are persistent pollutants routinely found in human blood. PFASs have been associated with health issues such as decreased birth weight and impaired vaccination response in children. Substitutes to these PFASs, such as ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate (GenX) have been introduced, although hazard information is limited. Human induced pluripotent stem cell (hiPSC) based models are valuable for studying these compounds, as they mimic human embryonic development. We used our recently developed PluriBeat assay to investigate PFOS, PFOA and GenX for effects on early embryonic development in vitro. In our assay hiPSCs go through the early stages of embryonic development in 3D cultures of embryoid bodies (EBs) that mimic the human blastocyst until they finally form beating cardiomyocytes. Both PFOS and PFOA had a strong effect on cardiomyocyte differentiation at non-cytotoxic concentrations, with PFOS being more potent than PFOA. Moreover, both compounds decreased EB size at the highest test concentrations. GenX induced a weak concentration-dependent effect on differentiation of one hiPSC line, but not of another. Transcriptional analysis of mRNA from the cardiomyocytes showed that PFOS increased expression of the early cardiac marker ISL1, whereas PFOA decreased expression of the cardiomyocyte marker MYH7. This suggest that PFOS and PFOA perturb cardiomyocyte differentiation by disrupting molecular pathways similar to those taking place in the developing embryo. Based on these findings, we conclude that our PluriBeat assay has the potential to become a valuable, sensitive model system for elucidating embryotoxic effects of PFASs in future.

Risk to human health related to the presence of perfluoroalkyl substances in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluoroalkyl substances (PFASs) in food. Based on several similar effects in animals, toxicokinetics and observed concentrations in human blood, the CONTAM Panel decided to perform the assessment for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS. These made up half of the lower bound (LB) exposure to those PFASs with available occurrence data, the remaining contribution being primarily from PFASs with short half-lives. Equal potencies were assumed for the four PFASs included in the assessment. The mean LB exposure in adolescents and adult age groups ranged from 3 to 22, the 95th percentile from 9 to 70 ng/kg body weight (bw) per week. Toddlers and 'other children' showed a twofold higher exposure. Upper bound exposure was 4- to 49-fold higher than LB levels, but the latter were considered more reliable. 'Fish meat', 'Fruit and fruit products' and 'Eggs and egg products' contributed most to the exposure. Based on available studies in animals and humans, effects on the immune system were considered the most critical for the risk assessment. From a human study, a lowest BMDL 10 of 17.5 ng/mL for the sum of the four PFASs in serum was identified for 1-year-old children. Using PBPK modelling, this serum level of 17.5 ng/mL in children was estimated to correspond to long-term maternal exposure of 0.63 ng/kg bw per day. Since accumulation over time is important, a tolerable weekly intake (TWI) of 4.4 ng/kg bw per week was established. This TWI also protects against other potential adverse effects observed in humans. Based on the estimated LB exposure, but also reported serum levels, the CONTAM Panel concluded that parts of the European population exceed this TWI, which is of concern.

The correlated expression of immune and energy metabolism related genes in the response to Salmonella enterica serovar Enteritidis inoculation in chicken

Background

Salmonella enterica serovar Enteritidis (SE) is one of the food-borne pathogenic bacteria, which affects poultry production and poses severe threat to human health. The correlation of immune system and metabolism in chicken after SE inoculation is important but not clear. In the current study, we identified the expression of immune and energy metabolism related genes using quantitative PCR to evaluate the correlation between immune system and energy metabolism against SE inoculation in Jining Bairi chicken.

Results

ATP5G1, ATP5G3 and ND2 were significantly up-regulated at 1 dpi (day post inoculation), and ATP5E, ATP5G1, ATP5G3 were significantly down-regulated at 7 dpi (P < 0.05). IL-8 and IL-1β were significantly down-regulated at 1 dpi, IL-8 and IL-18 were significantly down-regulated at 3 dpi, IL-8 and BCL10 were significantly up-regulated at 7 dpi (P < 0.05).

Conclusions

These findings indicate that the correlation between immune and energy metabolism related genes gradually change with time points post SE inoculation, from one homeostasis to an opposite homeostasis with 3 dpi as a turning point. These results will pave the foundation for the relationship between immune system and energy metabolism in the response to SE inoculation in chicken.

Association between serum concentrations of perfluoroalkyl substances (PFAS) and expression of serum microRNAs in a cohort highly exposed to PFAS from drinking water

BACKGROUND

Perfluoroalkyl substances (PFAS) are widespread synthetic substances with various adverse health effects. Not much is known about the modes of action of PFAS toxicity, but one likely mechanism is alteration of microRNA expression.

OBJECTIVES

To investigate whether PFAS exposure is associated with altered microRNA expression in serum.

METHODS

We selected women from the Ronneby cohort, with high exposure to perfluorooctane sulfonic acid (PFOS) and perfluorohexane sulfonic acid (PFHxS), emanating from drinking water contaminated by firefighting foam, and a control group of women from a neighbouring municipality without drinking water contamination. Serum levels of PFAS were analysed using LC/MS/MS. High coverage microRNA expression was analysed by next generation sequencing (NGS) in 53 individuals to screen for microRNAs associated with PFAS exposure. After verification by qPCR, associations between PFAS exposure and expression of 18 selected microRNAs were validated by qPCR in 232 individuals. In silico functional analyses were performed using Ingenuity pathway analysis (IPA).

RESULTS

Three microRNAs were consistently associated with PFAS exposure in the different steps of the study: miR-101-3p, miR-144-3p and miR-19a-3p (all downregulated with increasing exposure). In silico functional analyses suggested that these PFAS-associated microRNAs were annotated to e.g. cardiovascular function and disease, Alzheimer's disease, growth of cancer cell lines and cancer. Seven predicted target genes for the downregulated microRNAs were annotated to PFAS in IPA knowledge database: DNA methyltransferase 3 alpha (DNMT3a), epidermal growth factor receptor (EGFR), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), nuclear receptor subfamily 1, group H, member 3 (NR1H3), peroxisome proliferator-activated receptor alpha (PPARα), prostaglandin-endoperoxide synthase 2 (PTGS2), and tumour growth factor alpha (TGFα).

DISCUSSION

PFAS exposure was associated with downregulation of specific microRNAs. Further, in silico functional analyses suggest potential links between the specific PFAS-associated microRNAs, specific microRNA target genes and possibly also health effects.

Probing the Cell Apoptosis Pathway Induced by Perfluorooctanoic Acid and Perfluorooctane Sulfonate at the Subcellular and Molecular Levels

As typical perfluorinated compounds (PFCs), perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been detected in various environmental media and their toxic effects have been extensively studied. Nevertheless, it remains unclear how PFCs cause cell apoptosis in healthy hepatocytes by inducing oxidative stress at the subcellular and molecular levels. In this study, the apoptotic pathways induced by PFOA and PFOS were explored. Besides, the effects of PFCs on the structure and function of lysozyme (LYZ) were investigated. After PFOA and PFOS exposure, the cell membrane and mitochondrial membrane potential were damaged. Further, PFOA and PFOS increased intracellular Ca²⁺ levels to 174.41 ± 1.70 and 158.91 ± 5.94%, respectively. Ultimately, caspase-3 was activated, causing cell apoptosis. As an indirect antioxidant enzyme, the molecular structure of LYZ was destroyed after interacting with PFOA and PFOS. Both PFOA and PFOS bound to the active center of LYZ, leading to the decrease of LYZ activity to 91.26 ± 0.78 and 76.01 ± 4.86%, respectively. This study demonstrates that PFOA and PFOS inhibit LYZ function, which can reduce the body's ability to resist oxidative stress, and then lead to mitochondria-mediated apoptosis.

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

The wide use of perfluorooctane sulfonate (PFOS) has led to increasing concern about its human health risks over the past decade. In vivo and in vitro studies are important and effective means to ascertain the toxic effects of PFOS on humans and its toxic mechanisms. This article systematically reviews the human health risks of PFOS based on the currently known facts found by in vivo and in vitro studies from 2008 to 2018. Exposure to PFOS has caused hepatotoxicity, neurotoxicity, reproductive toxicity, immunotoxicity, thyroid disruption, cardiovascular toxicity, pulmonary toxicity, and renal toxicity in laboratory animals and many in vitro human systems. These results and related epidemiological studies confirmed the human health risks of PFOS, especially for exposure via food and drinking water. Oxidative stress and physiological process disruption based on fatty acid similarity were widely studied mechanisms of PFOS toxicity. Future research for assessing the human health risks of PFOS is recommended in the chronic toxicity and molecular mechanisms, the application of various omics, and the integration of toxicological and epidemiological data.

Risk to human health related to the presence of perfluorooctane sulfonic acid and perfluorooctanoic acid in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in food. Regarding PFOS and PFOA occurrence, the final data set available for dietary exposure assessment contained a total of 20,019 analytical results (PFOS n = 10,191 and PFOA n = 9,828). There were large differences between upper and lower bound exposure due to analytical methods with insufficient sensitivity. The CONTAM Panel considered the lower bound estimates to be closer to true exposure levels. Important contributors to the lower bound mean chronic exposure were 'Fish and other seafood', 'Meat and meat products' and 'Eggs and egg products', for PFOS, and 'Milk and dairy products', 'Drinking water' and 'Fish and other seafood' for PFOA. PFOS and PFOA are readily absorbed in the gastrointestinal tract, excreted in urine and faeces, and do not undergo metabolism. Estimated human half-lives for PFOS and PFOA are about 5 years and 2-4 years, respectively. The derivation of a health-based guidance value was based on human epidemiological studies. For PFOS, the increase in serum total cholesterol in adults, and the decrease in antibody response at vaccination in children were identified as the critical effects. For PFOA, the increase in serum total cholesterol was the critical effect. Also reduced birth weight (for both compounds) and increased prevalence of high serum levels of the liver enzyme alanine aminotransferase (ALT) (for PFOA) were considered. After benchmark modelling of serum levels of PFOS and PFOA, and estimating the corresponding daily intakes, the CONTAM Panel established a tolerable weekly intake (TWI) of 13 ng/kg body weight (bw) per week for PFOS and 6 ng/kg bw per week for PFOA. For both compounds, exposure of a considerable proportion of the population exceeds the proposed TWIs.

Circulating levels of perfluoroalkyl substances and left ventricular geometry of the heart in the elderly

AIMS

Some persistent organic pollutants (POPs) such as hexachlorobenzene (HCB) and some polychlorinated biphenyls (PCBs) have been shown to interfere with myocardial function and geometry. We therefore investigated if also another group of POPs: per- and polyfluoroalkyl substances (PFASs) were associated with alterations in left ventricular geometry.

METHODS

801 subjects aged 70 years were investigated in a cross-sectional study within the scope of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Eight PFASs were detected in >75% of participants´ plasma by ultra-performance liquid chromatograph/tandem mass spectrometry. Left ventricular geometry was determined by echocardiography. Multivariable linear regression was used to investigate the associations between PFASs and left ventricular geometry of the heart after exclusion of subjects with previous myocardial infarction (n = 72).

RESULTS

When adjusting for multiple comparisons, none of the eight PFASs evaluated were significantly related to left ventricular mass. However, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) were related to relative wall thickness (RWT) in a negative fashion (p < 0.0021). Besides being inversely related to RWT, PFNA was also positively related to left ventricular end-diastolic volume (LVEDD) (p < 0.0021). These analyses were adjusted for traditional cardiovascular risk factors.

CONCLUSION

In this cross-sectional study, several of the PFASs evaluated, especially PFNA, were related to myocardial geometry: a reduction in relative wall thickness and an increase in left ventricular diameter following adjustment for traditional cardiovascular risk factors, suggesting a role for PFASs in cardiac remodeling.

Mitochondrial toxicity of perfluorooctane sulfonate in mouse embryonic stem cell-derived cardiomyocytes

Perfluorooctane sulfonate (PFOS) is a persistent organic contaminant that may cause cardiotoxicity in animals and humans. However, little is known about the underlying mechanism by which it affects the organelle toxicity in cardiomyocytes during the cardiogenesis. Our previous proteomic study showed that differences of protein expression mainly existed in mitochondria of cardiomyocytes differentiated from embryonic stem (ES) cells after exposure to PFOS. Here, we focused on mitochondrial toxicity of PFOS in ES cell-derived cardiomyocytes. The cardiomyogenesis from ES cells in vitro was inhibited, and the expression of L-type Ca²⁺ channel (LTCC) was decreased to interrupt [Ca²⁺]_c transient amplitude in cardiomyocytes after PFOS treatment. Transmission electron microscope revealed that swollen mitochondrion with vacuole in PFOS-treated cells. Meanwhile, mitochondrial transmembrane potential (ΔΨm) was declined and ATP production was lowered. These changes were related to the increased EGFR phosphorylation, activated Rictor signaling, then mediated HK2 binding to mitochondrial membrane. Furthermore, PFOS reduced the interaction of IP3R-Grp75-VDAC and accumulated intracellular fatty acids by activating Rictor, thereby attenuating PGC-1α and Mfn2 expressions, then destroying mitochondria-associated endoplasmic reticulum membrane (MAM), which resulted in the decrease of [Ca²⁺]_mito transient amplitude triggered by ATP. In conclusion, mitochondrial structure damages and abnormal Ca²⁺ shuttle were the important aspects in PFOS-induced cardiomyocytes toxicity from ES cells by activating Rictor signaling pathway.

Reconnaissance of dioxin-like and estrogen-like toxicities in sediments of Taean, Korea-seven years after the Hebei Spirit oil spill

Oil spills near the coastlines may damage marine and intertidal ecosystem. Constituents of the oil have been reported to cause toxic consequences mediated by aryl hydrocarbon receptor (AhR), and estrogen receptor (ER). In the present study, AhR- and ER-mediated toxicities of coastal sediments of Taean were investigated seven years after Hebei Spirit oil spill (HSOS). Sediment samples were collected on June and October 2014 from seven locations along the Taean coastline, where signs of oil spill were detected. Sediment samples were extracted in Soxhlet extractors and further processed through activated silica gels to separate into four fractions; F1 (saturate hydrocarbons), F2 (aromatic hydrocarbons), F3 (resins and polar compounds), and F4 (residues). ER-mediated and AhR-mediated potencies (% E2_max and % TCDD_max) of each fraction were determined using MVLN cells and H4IIE-luc cells, respectively. F2 and F3 fractions of Sinduri 1, Sinduri 2, and Sogeunri 1 samples showed greater AhR-mediated potencies (up to 107% TCDD_max). Chemical analysis revealed that PAH components are correlated with AhR-binding activities. The % E2_max results varied by sample: While there was no noticeable induction of ER-dependent responses (<45%), some aromatics fractions (F2) exhibited the highest ER-mediated responses. Compared with previous reports from the same sites, both AhR-mediated and ER-mediated potencies have decreased over time. Nevertheless, AhR-mediated potencies could be identified in the environmental samples even after 7 years of the incident. Therefore, possible ecosystem implications of these findings should be further investigated.

Perfluorooctane sulfonate exposure causes gonadal developmental toxicity in Caenorhabditis elegans through ROS-induced DNA damage

Perfluorooctane sulfonate (PFOS), a common persistent organic pollutant, has been reported to show potential developmental toxicity in many animal studies. However, little was known about its effects on reproductive tissues, especially in the germ line. In the present study, Caenorhabditis elegans was used as an in vivo experimental model to study the developmental toxicity caused by PFOS exposure, especially in the gonads. Our results showed that PFOS exposure significantly retarded gonadal development, as shown by the increased number of worms that remained in the larval stages after hatched L1-stage larvae were exposed to PFOS for 72 h. Investigation of germ line proliferation following PFOS exposure showed that the number of total germ cells reduced in a dose-dependent manner when L1-stage larvae were exposed to 0-25.0 μM PFOS. PFOS exposure induced transient mitotic cell cycle arrest and apoptosis in the germ line. Quantification of DNA damage in proliferating germ cells and production of reactive oxygen species (ROS) showed that distinct foci of HUS-1:GFP and ROS significantly increased in the PFOS-treated groups, whereas the decrease in mitotic germ cell number and the enhanced apoptosis induced by PFOS exposure were effectively rescued upon addition of dimethyl sulfoxide (DMSO) and mannitol (MNT). These results suggested that ROS-induced DNA damage might play a pivotal role in the impairment of gonadal development indicated by the reduction in total germ cells, transient mitotic cell cycle arrest, and apoptosis.

Prenatal exposure to PFOS caused mitochondia-mediated apoptosis in heart of weaned rat

Perfluorooctanyl sulfonate (PFOS), a cardiac toxicity compound, has been widely detected in the environment and in organisms. However, the toxic mechanism is not clear. Our previous study indicated that prenatal PFOS exposure led to swollen mitochondrial with vacuolar structure and loss of cristae in offsping's heart. The purpose of this study was to investigate the effect of PFOS on the apoptosis in developing heart and mitochondria-mediated apoptosis pathway. Pregnant Sprague-Dawley (SD) rats were exposed to PFOS at doses of 0.1, 0.6, and 2.0 mg/kg-d and 0.05% Tween 80 as control by gavage from gestation day 2 (GD 2) to GD 21. Apoptosis, as well as expression of apoptosis related genes associated with mitochondrial-mediated apoptosis pathway, including p53, bcl-2, bax, cytochrome c, caspase-9, and caspase-3 were analyzed in heart tissues from weaned (postnatal day 21, PND 21) offspring. The results showed that prenatal PFOS exposure resulted in apoptosis in the offspring's heart. The mRNA and protein expression levels of p53, bax, cytochrome c, caspase-9, and caspase-3 in the offspring's heart were enhanced in various PFOS-treated groups, meanwhile, the bcl-2 expression levels were decreased. Our results indicated that prenatal PFOS exposure induced the apoptosis of weaned offspring rat heart tissue via mitochondria-mediated apoptotic pathway.

Physiological and pathological roles of mitochondrial SLC25 carriers

The mitochondrion relies on compartmentalization of certain enzymes, ions and metabolites for the sake of efficient metabolism. In order to fulfil its activities, a myriad of carriers are properly expressed, targeted and folded in the inner mitochondrial membrane. Among these carriers, the six-transmembrane-helix mitochondrial SLC25 (solute carrier family 25) proteins facilitate transport of solutes with disparate chemical identities across the inner mitochondrial membrane. Although their proper function replenishes building blocks needed for metabolic reactions, dysfunctional SLC25 proteins are involved in pathological states. It is the purpose of the present review to cover the current knowledge on the role of SLC25 transporters in health and disease.

High-fat intake during pregnancy and lactation exacerbates high-fat diet-induced complications in male offspring in mice

Altered fetal environments, such as a high-fat milieu, induce metabolic abnormalities in offspring. Different postnatal environments reveal the predisposition for adult diseases that occur during the fetal period. This study investigates the ability of a maternal high-fat diet (HFD) to program metabolic responses to HFD reexposure in offspring after consuming normal chow for 23 weeks after weaning. Wild-type CD1 females were fed a HFD (H) or control (C) chow during pregnancy and lactation. At 26 weeks of age, offspring were either reexposed (H-C-H) or newly exposed (C-C-H) to the HFD for 19 weeks. Body weight was measured weekly, and glucose and insulin tolerance were measured after 10 and 18 weeks on the HFD. The metabolic profile of offspring on a HFD or C diet during pregnancy and lactation and weaned onto a low-fat diet was similar at 26 weeks. H-C-H offspring gained more weight and developed larger adipocytes after being reintroduced to the HFD later in life than C-C-H. H-C-H mice were glucose and insulin intolerant and showed reduced gene expression of cox6a2 and atp5i in muscle, indicating mitochondrial dysfunction. In adipocytes, the expression of slc2a4, srebf1, and adipoq genes was decreased in H-C-H mice compared with C-C-C, indicating insulin resistance. H-C-H showed extensive hepatosteatosis, accompanied by increased gene expression for cd36 and serpin1, compared with C-C-H. Perinatal exposure to a HFD programs a more deleterious response to a HFD challenge later in life even after an interval of normal diet in mice.

Deep sequencing-based transcriptome profiling analysis of Oryzias melastigma exposed to PFOS

Oryzias melastigma is a newly emerging marine fish model. However, the application of this model has been restricted because of the lack of genomic information. Perfluorooctane sulfonate (PFOS), a persistent organic pollutant, is widely distributed in the estuarine/marine environment. The toxicological effects of PFOS on organisms, especially on marine fish species, remain largely unknown. In this study, the transcriptome of O. melastigma was sequenced using newly developed sequencing technology (Illumina RNA-seq). A total of 145,394 unigenes were obtained with 565 bp of unigene N50. These genes were further enriched in various molecular pathways involved in the toxicological response. We also investigated the transcriptional response of O. melastigma embryos after PFOS exposure from 2 days post fertilization (dpf) to 6 dpf by digital gene expression (DGE) technology. The differentially expressed genes were related to neurobehavioral defects, mitochondrial dysfunction and the metabolism of proteins and fats. A further quantitative RT-PCR study showed the down-regulation of ATP synthase and the up-regulation of uncoupling protein 2 (UCP2), which indicated mitochondrial dysfunction. In all, the transcriptome data represent the most comprehensive expressed gene catalog for O. melastigma and will serve as an important reference for various marine fish that are yet to be sequenced. The transcriptome profiling of O. melastigma embryos after exposure to PFOS are also expected to improve our current understanding of the molecular toxicology of PFOS.