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

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.

Structural and molecular changes in the rat myocardium following perfluoroctane sulfonate (PFOS) exposure are mitigated by quercetin via modulating HSP 70 and SERCA 2

Perfluorooctane sulfonate (PFOS) is a man-made fluorinated compound employed in a variety of industrial and civilian applications. Due to its long elimination half-life and promotion of oxidative stress and inflammation, it is one of the most abundant organic contaminants. The present study was designed to determine the cytotoxic effect of PFOS on adult male rat cardiac tissue and to assess the cardioprotective role of the flavonoid quercetin (Que), which possesses antioxidant, anti-inflammatory, and anti-apoptotic properties. Twenty-four adult male Sprague-Dawley rats were randomly divided into four equal groups: Group I (Control). Group II (Que) received Que (75 mg/kg/day for 4 weeks) by oral gavage. Group III (PFOS group): supplemented orally with PFOS (20 mg/kg/day for 4 weeks) and Group IV (PF OS/Que). The rat heart was processed for histological, immunohistochemical, and gene expression studies. The PFOS group showed histological alterations in the myocardium that were partially reversed by the administration of Que. The inflammatory biomarkers (TNF, IL-6, and IL-1), lipid profile, TSH, MDA, and serum cardiac enzymes (LDH and CK-MB) were all altered. These findings collectively suggest that PFOS had adverse effects on the cardiac muscle structure, and these effects were alleviated by quercetin, which is a promising cardioprotective flavonoid.

Public health evaluation of PFAS exposures and breastfeeding: a systematic literature review

Per- and polyfluoroalkyl substances (PFAS) are a class of man-made chemicals that are persistent in the environment. They can be transferred across the placenta to fetuses and through human milk to infants. The American Academy of Pediatrics advises that the benefits of breastfeeding infants almost always outweigh the potential risks of harm from environmental chemicals. However, there are few chemical-specific summaries of the potential harms of exposure to PFAS during the neonatal period through breastfeeding. This systematic review explores whether exposure to PFAS through breastfeeding is associated with adverse health outcomes among infants and children using evidence from human and animal studies. Systematic searches identified 4297 unique records from 7 databases. The review included 37 total articles, including 9 animal studies and 1 human study measuring the direct contribution of exposure of the infant or pup through milk for any health outcome. Animal studies provided evidence of associations between exposure to PFOA through breastfeeding and reduced early life body weight gain, mammary gland development, and thyroid hormone levels. They also provided limited evidence of associations between PFOS exposure through breastfeeding with reduced early life body weight gain and cellular changes in the hippocampus. The direct relevance of any of these outcomes to human health is uncertain, and it is possible that many adverse health effects of exposure through breastfeeding have not yet been studied. This review documents the current state of science and highlights the need for future research to guide clinicians making recommendations on infant feeding.

Perfluorooctane sulfonate-induced apoptosis in kidney cells by triggering the NOX4/ROS/JNK axis and antagonism of cannabidiol

Perfluorooctane sulfonate (PFOS) is one of the persistent organic pollutants (POPs), which can cause severe nephrotoxicity in mammals. Cannabinol (CBD), a nonpsychoactive cannabinoid obtained from the cannabis plant, has attracted attention in recent years for its excellent antioxidant properties. NADPH oxidase 4 (NOX4) has an important effect in supporting normal renal physiological function. The potential mechanisms of PFOS nephrotoxicity and whether CBD can prevent renal damage caused by PFOS remain unclear. This work aimed to study the mechanisms of PFOS-induced kidney damage and the protective role of CBD against PFOS-induced kidney damage. We demonstrated that PFOS led to renal insufficiency and structural damage in mice, induced overexpression of NOX4 and the onset of oxidative stress, and activated apoptosis of the mitochondrial pathway via the JNK signaling pathway. However, treatment with CBD reversed these changes. For further investigation of the potential mechanism of PFOS-induced renal cell apoptosis, the expression of NOX4 was inhibited in vitro experiments using Apocynin, an effective NOX4 inhibitor. The outcomes showed that PFOS-induced ROS production and JNK signaling pathway activation and apoptosis in human embryonic kidney (HEK293) cells were significantly reduced after inhibition of NOX4. This suggests that PFOS-induced NOX4 overexpression serves as an upstream event for JNK pathway activation. In conclusion, the findings suggest that PFOS induces apoptosis in renal cells via the NOX4/ROS/JNK pathway. Meanwhile, CBD alleviated PFOS-induced renal apoptosis through the inhibition of NOX4/ROS/JNK axis activation.

Cannabidiol Alleviates Perfluorooctanesulfonic Acid-Induced Cardiomyocyte Apoptosis by Maintaining Mitochondrial Dynamic Balance and Energy Metabolic Homeostasis

Perfluorooctanesulfonic acid (PFOS), a fluorine-containing organic compound, can be widely detected in the environment and living organisms. Accumulating evidence has shown that PFOS breaks through different biological barriers resulting in cardiac toxicity, but the underlying molecular mechanisms remain unclear. Cannabidiol (CBD) is a nonpsychoactive cannabinoid without potential adverse cardiotoxicity and has antioxidant and anti-inflammatory properties that reduce multiorgan damage and dysfunction. For these reasons, the aim of this study was to research how PFOS caused heart injury and whether CBD could attenuate PFOS-induced heart injury. Mice were fed PFOS (5 mg/kg) and/or CBD (10 mg/kg) in vivo. In vitro, H9C2 cells were intervened with PFOS (200 μM) and/or CBD (10 μM). After PFOS exposure, oxidative stress levels and the mRNA and protein expression of apoptosis-related markers increased distinctly, accompanied by mitochondrial dynamic imbalance and energy metabolism disorders in mouse heart and H9C2 cells. Moreover, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, acridine orange/ethidium bromide staining and Hoechst 33258 staining signaled that the number of apoptotic cells increased after exposure to PFOS. Noteworthy, CBD simultaneous treatment alleviated a series of damages caused by PFOS-mediated oxidative stress. Our results demonstrated that CBD could alleviate PFOS-induced mitochondrial dynamics imbalance and energy metabolism disorder causing cardiomyocyte apoptosis by improving the antioxidant capacity, suggesting that CBD may represent a novel cardioprotective strategy against PFOS-induced cardiotoxicity. Our findings facilitate the understanding of the cardiotoxic effects of PFOS and the important role of CBD in protecting cardiac health.

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.

1α,25-dihydroxyvitamin D3 supplementation alleviates perfluorooctanesulfonate acid-induced reproductive injury in male mice: Modulation of Nrf2 mediated oxidative stress response

Perfluorooctanesulfonate acid (PFOS) is a typical persistent organic pollutant that widely exists in the environment. To clarify the toxic effects and mechanisms of PFOS and to find effective intervention strategies have been attracted global attention. Here, we investigated the effects of PFOS on the male reproductive system and explored the potential protective role of 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂ D₃ ). Our results showed that 1α,25(OH)₂ D₃ intervention significantly improved PFOS-induced sperm quality decline and testicular damage. Moreover, 1α,25(OH)₂ D₃ aggrandized the total antioxidant capacity. Furthermore, after PFOS exposure, the transcription factor nuclear factor erythroid-related factor 2 (Nrf2) was adaptively increased together with its target genes, such as HO-1, NQO1, and SOD2. Meanwhile, 1α,25(OH)₂ D₃ ameliorated PFOS-induced augment of Nrf2 and target genes. These findings indicated that 1α,25(OH)₂ D₃ might attenuate PFOS-induced reproductive injury in male mice via Nrf2-mediated oxidative stress.

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.

Developmental toxicant exposures and sex-specific effects on epigenetic programming and cardiovascular health across generations

Despite substantial strides in diagnosis and treatment, cardiovascular diseases (CVDs) continue to represent the leading cause of death in the USA and around the world, resulting in significant morbidity and loss of productive years of life. It is increasingly evident that environmental exposures during early development can influence CVD risk across the life course. CVDs exhibit marked sexual dimorphism, but how sex interacts with environmental exposures to affect cardiovascular health is a critical and understudied area of environmental health. Emerging evidence suggests that developmental exposures may have multi- and transgenerational effects on cardiovascular health, with potential sex differences; however, further research in this important area is urgently needed. Lead (Pb), phthalate plasticizers, and perfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants with numerous adverse human health effects. Notably, recent evidence suggests that developmental exposure to each of these toxicants has sex-specific effects on cardiovascular outcomes, but the underlying mechanisms, and their effects on future generations, require further investigation. This review article will highlight the role for the developmental environment in influencing cardiovascular health across generations, with a particular emphasis on sex differences and epigenetic mechanisms. In particular, we will focus on the current evidence for adverse multi and transgenerational effects of developmental exposures to Pb, phthalates, and PFAS and highlight areas where further research is needed.

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.

ROS-Triggered Autophagy Is Involved in PFOS-Induced Apoptosis of Human Embryo Liver L-02 Cells

The liver is the primary target organ for perfluorooctane sulphonate (PFOS), a recently discovered persistent organic pollutant. However, the mechanisms mediating hepatotoxicity remain unclear. Herein, we explored the relationship between reactive oxygen species (ROS) and autophagy and apoptosis induced by PFOS in L-02 cells, which are incubated with different concentrations of PFOS (0, 50, 100, 150, 200, or 250 μmol/L) for 24 or 48 hrs at 37°C. The results indicated that PFOS exposure decreased cell activities, enhanced ROS levels in a concentration-dependent manner, decreased mitochondrial membrane potential (MMP), and induced autophagy and apoptosis. Compared with the control, 200 μmol/L PFOS increased ROS levels; enhanced the expression of Bax, cleaved-caspase-3, and LC3-II; induced autophagy; decreased MMP; and lowered Bcl-2, p62, and Bcl-2/Bax ratio. The antioxidant N-acetyl cysteine (NAC) protected MMP against PFOS-induced changes and diminished apoptosis and autophagy. Compared with 200 μmol/L PFOS treatment, NAC pretreatment reversed the increase in ROS, Bax, and cleaved-caspase-3 protein caused by PFOS, lowered the apoptosis rate increased by PFOS, and increased the levels of MMP and Bcl-2/Bax ratio decreased by PFOS. The autophagy inhibitor 3-methyladenine and chloroquine decreased apoptosis and cleaved-caspase-3 protein level and increased the Bcl-2/Bax ratio. In summary, our results suggest that ROS-triggered autophagy is involved in PFOS-induced apoptosis in L-02 cells.

Combined effects of BPA and PFOS on fetal cardiac development: In vitro and in vivo experiments

Analyses of the combined effects of different EDCs are both important and difficult. This study attempts to evaluate the individual and combined effects of BPA and PFOS on heart development. Sprague-Dawley rats received individual or combined PFOS and BPA for 19 days during pregnancy. The results show that the combined BPA and PFOS exposure could lead to a morphological change in the fetal rat heart. An increase in the interventricular septal thickness (IVS) of approximately 20 % (391 μm in control vs 464 μm in combined exposure) was observed in the fetal rat hearts after the combined exposure to nearly 2000 μg/L PFOS and 100 μg/L BPA through drinking water. The total collagen and dynamin-related protein 1 (Drp1) mRNA level was increased in the fetal hearts exposed to the combination of 2000 μg/L PFOS and 100 μg/L BPA. However, the cell number in the IVS did not significantly change. Based on the previous literature, we believe that the combined exposure to BPA and PFOS had a synergistic effect on the thickness of the IVS. The combined exposure to 40 μg/L PFOS and 2 μg/L BPA failed to cause significant damage to the embryonic heart. The individual and combined effects and the mechanism of the effects of BPA and PFOS on heart development were further investigated by an in vitro study. Embryonic stem cells were administered individual or combined 10 ng/mL BPA and 100 ng/mL PFOS for 14 days during the cardiac differentiation period. The results show that exposure to the combination of 100 ng/mL PFOS and 10 ng/mL BPA could increase the cardiomyocyte size and collagen content. A selective inhibitor of Drp1, Mdivi-1, could inhibit the cardiomyocyte size enlargement but not the collagen content increase caused by the combined exposure. Thus, we believe that although the combined exposure to PFOS and BPA could affect mitochondrial biogenesis and collagen expression, these two effects seem to be relatively independent. Based on these results, this research concludes that combined exposure to PFOS and BPA could specifically lead to increased collagen and IVS thickening in heart development.

Perfluorooctane sulfonate induced toxicity in embryonic stem cell-derived cardiomyocytes via inhibiting autophagy-lysosome pathway

Perfluorooctane sulfonate (PFOS), a classic environmental pollutant, is reported to cause cardiotoxicity in animals and humans. It has been demonstrated that PFOS exposure down-regulates expression of cardiac-development related genes and proteins. However, the related mechanism of PFOS has not been fully elucidated. In the present study, the embryonic stem (ES) cells-derived cardiomyocytes (ESC-CMs) was employed to investigate PFOS-mediated mechanism in developmental toxicity of cardiomyocytes. Our previous study shows that PFOS induces cardiomyocyte toxicity via causing mitochondrial damage. Nevertheless, the underlying mechanism by which PFOS affects the autophagy-related mitochondrial toxicity in ESC-CMs remains unclear. Here, we found that PFOS induced the swelling of mitochondria and the autophagosome accumulation in ESC-CMs at 40 μM concentration. PFOS increased the levels of LC3-II, p62, and ubiquitinated proteins. PFOS also induced an increase of LC3 and p62 localization into mitochondria, indicating that mitophagy degradation was impaired. The results of autophagic flux using chloroquine and RFP-GFP-LC3 analysis showed that the accumulation of autophagosome was not caused by the formation but by the impaired degradation. PFOS was capable of blocking the fusion between autophagosome and lysosome. PFOS caused dysfunction of lysosomes because it down-regulated Lamp2a and cathepsin D, but it did not induced lysosome membrane permeabilization. Meanwhile, PFOS-mediated lysosomal function and the inhibitory effect of autophagic flux could be reversed by PP242 at 40 nM concentration, an mTOR inhibitor. Furthermore, PP242 restored PFOS-induced ATP depletion and mitochondrial membrane potential. In conclusion, PFOS induced mitochondrial dysfunction via blocking autophagy-lysosome degradation, leading to cardiomyocyte toxicity from ES cells.

F-53B and PFOS treatments skew human embryonic stem cell in vitro cardiac differentiation towards epicardial cells by partly disrupting the WNT signaling pathway

F-53B and PFOS are two per- and polyfluoroalkyl substances (PFASs) widely utilized in the metal plating industry as mist suppressants. Recent epidemiological studies have linked PFASs to cardiovascular diseases and alterations in heart geometry. However, we still have limited understanding of the effects of F-53B and PFOS on the developing heart. In this study, we employed a human embryonic stem cell (hESC)-based cardiac differentiation system and whole transcriptomics analyses to evaluate the potential developmental cardiac toxicity of F-53B and PFOS. We utilized F-53B and PFOS concentrations of 0.1-60 μM, covering the levels detected in human blood samples. We demonstrated that both F-53B and PFOS inhibited cardiac differentiation and promoted epicardial specification via upregulation of the WNT signaling pathway. Most importantly, the effects of F-53B were more robust than those of PFOS. This was because F-53B treatment disrupted the expression of more genes and led to lower cardiac differentiation efficiency. These findings imply that F-53B may not be a safe replacement for PFOS.

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.

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.

Interactions between three typical endocrine-disrupting chemicals (EDCs) in binary mixtures exposure on myocardial differentiation of mouse embryonic stem cell

In recent years, various kinds of endocrine-disrupting chemicals (EDCs) have been detected in human blood and urine. Thus, it was important to investigate the combined toxicity effect of EDCs. In the present study, we evaluated the individual and combined developmental toxicities of three classic EDCs: perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and bisphenol A (BPA) by embryonic stem cell test (EST). The similarities and differences between combination of same chemical group as well as different chemical groups were investigated in this research. Our results showed that the three compounds were all classified as weak embryotoxicity. The results of co-exposure revealed that there was synergistic action in combination of PFOS and BPA on myocardial differentiation. However, in all endpoints, the combined effects between PFOA with PFOS or BPA were both additive action. Therefore, we concluded that the additive effects were found in most different EDC mixtures whether they had similar structure or not. On the other hand, synergistic action was observed in a mixture of EDCs that belonged to a different chemical groups.

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.

Perfluorooctane sulfonate-induced testicular toxicity and differential testicular expression of estrogen receptor in male mice

Perfluorooctane sulfonate (PFOS, CAS#1763-23-1) causes male reproductive toxicities, but the underlying mechanisms are still unclear. In this study, 0, 0.5 and 10mg/kg/day PFOS were given by oral gavage to adult mice for 5 weeks. In the 10mg/kg group, serum testosterone levels decreased significantly. Sperm counts declined which might be associated with the decreased proliferation and increased apoptosis of germ cells. In relation to increased apoptosis, bax, cleaved caspase-9 and cleaved caspase-3 levels elevated significantly, indicating that PFOS induced germ cell apoptosis by activating the mitochondrial pathway. In addition, the increase in levels of testicular estrogen receptor (ER) β was observed in both 0.5 and 10mg/kg group, whereas a decrease in ERα expression was only observed in 10mg/kg group. These results suggested that the alterations in testicular ERs expression, together with decreased proliferation and increased apoptosis of germ cells, might be involved in PFOS-induced testicular toxicity.

PFOS Disturbs BDNF-ERK-CREB Signalling in Association with Increased MicroRNA-22 in SH-SY5Y Cells

Perfluorooctane sulfonate (PFOS), a ubiquitous environmental pollutant, is neurotoxic to mammalian species. However, the underlying mechanism of its neurotoxicity was unclear. We hypothesized that PFOS suppresses BDNF expression to produce its neurotoxic effects by inhibiting the ERK-CREB pathway. SH-SY5Y human neuroblastoma cells were exposed to various concentrations of PFOS to examine the role of the BDNF-ERK-CREB signalling pathway in PFOS-induced apoptosis and cytotoxicity. Furthermore, to ascertain the mechanism by which PFOS reduces BDNF signalling, we examined the expression levels of miR-16 and miR-22, which potentially regulate BDNF mRNA translation at the posttranscriptional level. Results indicated that PFOS significantly decreased cell viability and induced apoptosis in SH-SY5Y cells. In addition, BDNF and pERK protein levels decreased after PFOS treatment; however, pCREB protein levels were significantly elevated in PFOS treated groups. TrkB protein expression increased in the 10 μM and 50 μM PFOS groups and significantly decreased in the 100 μM PFOS group. Our results demonstrated that PFOS exposure decreased miR-16 expression and increased miR-22 expression, which may represent a possible mechanism by which PFOS decreases BDNF protein levels. PFOS may inhibit BDNF-ERK-CREB signalling by increasing miR-22 levels, which may, in part, explain the mechanism of PFOS neurotoxicity.

Reduction of progesterone, estradiol and hCG secretion by perfluorooctane sulfonate via induction of apoptosis in human placental syncytiotrophoblasts

INTRODUCTION

Perfluorooctane sulfonate (PFOS) is widely used as surfactants, lubricants, adhesives, fire retardants and propellants. Animal experiments have shown that PFOS can potentially influence reproductive function. The objective of the present study was to investigate the effects of PFOS on the endocrine function of human placental syncytiotrophoblasts.

METHODS

Primary human placental cytotrophoblasts were isolated from term placenta. After syncytialization, the levels of aromatase and apoptosis-related proteins including caspase3, Bcl-2 and Bax were examined after treatment with PFOS from 0.0001 μM to 1 μM or PFOS (0.1 μM) in the presence and absence of apoptosis inhibitor Z-VAD-FMK (30 μM) for 24 h.

RESULTS

PFOS suppressed aromatase level and the secretion of estradiol, hCG and progesterone in a concentration-dependent manner from 0.0001 μM to 1 μM with a significant inhibition at 0.001 μM and above in human placental syncytiotrophoblasts. Furthermore PFOS reduced cell viability and induced apoptosis in human placental syncytiotrophoblasts as revealed by increases of pro-apoptosis proteins such as Bax and cleaved-caspase3, and decreases of pro-caspase3 and anti-apoptosis protein Bcl-2. The apoptosis induced by PFOS was further illustrated by increased DNA fragmentation and nuclear condensation. Blocking apoptosis with pan-caspase inhibitor Z-VAD-FMK, the impairment of placental endocrine function by PFOS was restored.

DISCUSSION

These results indicate that PFOS may disrupt the secretion of hCG, progesterone and estradiol by human placental syncytiotrophoblasts via induction of apoptosis.