The effects of decabromodiphenyl ether on glycolipid metabolism and related signaling pathways in mice

Nano‑selenium alleviates the pyroptosis of cardiovascular endothelial cells in chicken induced by decabromodiphenyl ether through ERS-TXNIP-NLRP3 pathway

Decabromodiphenyl ether (BDE-209) is one of the most widely used flame retardants that can infect domestic and wildlife through contaminated feed. Nano‑selenium (Nano-Se) has the advantage of enhancing the anti-oxidation of cells. Nonetheless, it remains uncertain whether Nano-Se can alleviate vascular Endothelial cells damage caused by BDE-209 exposure in chickens. Therefore, we established a model with 60 1-day-old chickens, and administered BDE-209 intragastric at a ratio of 400 mg/kg bw/d, and mixed Nano-Se intervention at a ratio of 1 mg/kg in the feed. The results showed that BDE-209 could induce histopathological and ultrastructural changes. Additionally, exposure to BDE-209 led to cardiovascular endoplasmic reticulum stress (ERS), oxidative stress and thioredoxin-interacting protein (TXNIP)-pyrin domain-containing protein 3 (NLRP3) pathway activation, ultimately resulting in pyroptosis. Using the ERS inhibitor 4-PBA in Chicken arterial endothelial cells (PAECs) can significantly reverse these changes. The addition of Nano-Se can enhance the body's antioxidant capacity, inhibit the activation of NLRP3 inflammasome, and reduce cellular pyroptosis. These results suggest that Nano-Se can alleviate the pyroptosis of cardiovascular endothelial cells induced by BDE-209 through ERS-TXNIP-NLRP3 pathway. This study provides new insights into the toxicity of BDE-209 in the cardiovascular system and the therapeutic effects of Nano-Se.

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

BDE-209-induced genotoxicity, intestinal damage and intestinal microbiota dysbiosis in zebrafish (Danio Rerio)

The environmental presence of polybrominated diphenyl ethers (PBDEs) is ubiquitous due to their wide use as brominated flame retardants in industrial products. As a common congener of PBDEs, decabromodiphenyl ether (BDE-209) can pose a health risk to animals as well as humans. However, to date, few studies have explored BDE-209's toxic effects on the intestinal tract, and its relevant mechanism of toxicity has not been elucidated. In this study, adult male zebrafish were exposed to BDE-209 at 6 μg/L, 60 μg/L and 600 μg/L for 28 days, and intestinal tissue and microbial samples were collected for analysis to reveal the underlying toxic mechanisms. Transcriptome sequencing results demonstrated a dose-dependent pattern of substantial gene differential expression in the group exposed to BDE-209, and the differentially expressed genes were mainly concentrated in pathways related to protein synthesis and processing, redox reaction, and steroid and lipid metabolism. In addition, BDE-209 exposure caused damage to intestinal structure and barrier function, and promoted intestinal oxidative stress, inflammatory response, apoptosis and steroid and lipid metabolism disorders. Mechanistically, BDE-209 induced intestinal inflammation by increasing the levels of TNF-α and IL-1β and activating the NFκB signaling pathway, and might induce apoptosis through the p53-Bax/Bcl2-Caspase3 pathway. BDE-209 also significantly inhibited the gene expression of rate-limiting enzymes such as Sqle and 3βhsd (p < 0.05) to inhibit cholesterol synthesis. In addition, BDE-209 induced lipid metabolism disorders through the mTOR/PPARγ/RXRα pathway. 16S rRNA sequencing results showed that BDE-209 stress reduced the richness and diversity of intestinal microbiota, and reduced the abundance of probiotics (e.g., Bifidobacterium and Faecalibacterium). Overall, the results of this study help to clarify the intestinal response mechanism of BDE-209 exposure, and provide a basis for evaluating the health risks of BDE-209 in animals.

Toxic Effects and Mechanisms of Polybrominated Diphenyl Ethers

Polybrominated diphenyl ethers (PBDEs) are a group of flame retardants used in plastics, textiles, polyurethane foam, and other materials. They contain two halogenated aromatic rings bonded by an ester bond and are classified according to the number and position of bromine atoms. Due to their widespread use, PBDEs have been detected in soil, air, water, dust, and animal tissues. Besides, PBDEs have been found in various tissues, including liver, kidney, adipose, brain, breast milk and plasma. The continued accumulation of PBDEs has raised concerns about their potential toxicity, including hepatotoxicity, kidney toxicity, gut toxicity, thyroid toxicity, embryotoxicity, reproductive toxicity, neurotoxicity, and immunotoxicity. Previous studies have suggested that there may be various mechanisms contributing to PBDEs toxicity. The present study aimed to outline PBDEs' toxic effects and mechanisms on different organ systems. Given PBDEs' bioaccumulation and adverse impacts on human health and other living organisms, we summarize PBDEs' effects and potential toxicity mechanisms and tend to broaden the horizons to facilitate the design of new prevention strategies for PBDEs-induced toxicity.

The effects of brominated flame retardants (BFRs) on pro-atherosclerosis mechanisms

Brominated flame-retardants (BFRs) are environmental endocrine disruptors, comprising several pollutants, which potentially affect the endocrine system and cause dysfunction and disease. Widespread BFR exposure may cause multisystem toxicity, including cardiovascular toxicity in some individuals. Studies have shown that BFRs not only increase heart rate, induce arrhythmia and cardiac hypertrophy, but also cause glycolipid metabolism disorders, vascular endothelial dysfunction, and inflammatory responses, all of which potentially induce pre-pathological changes in atherosclerosis. Experimental data indicated that BFRs disrupt gene expression or signaling pathways, which cause vascular endothelial dysfunction, lipid metabolism-related disease, inflammation, and possibly atherosclerosis. Considerable evidence now suggests that BFR exposure may be a pro-atherosclerotic risk factor. In this study, we reviewed putative BFR effects underpinning pro-atherosclerosis mechanisms, and focused on vascular endothelial cell dysfunction, abnormal lipid metabolism, pro-inflammatory cytokine production and foam cell formation. Consequently, we proposed a scientific basis for preventing atherosclerosis by BFRs and provided concepts for further research.

Ferroptosis mediates decabromodiphenyl ether-induced liver damage and inflammation

Decabromodiphenyl ether (BDE-209) is an environmental toxin. Increasing evidence showed that BDE-209 exposure induced liver injury, but the mechanism still remains unknown. The present study explored the effect and mechanism of ferroptosis on hepatotoxicity triggered by BDE-209 in vivo and in vitro. In vivo experiment, ICR mice were exposed to BDE-209 for 50 days, and then recovered for 50 days; HepG2 and L02 cells were treated with BDE-209 or/and ferrostatin-1 (Fer-1) for establishing in vitro model. In vivo, the results showed that BDE-209 accumulated in liver and induced liver damage, increased Fe²⁺ and MDA contents, and blocked the activation of SLC7A11/GSH/GPX4 pathway in liver; BDE-209 also activated IKK/IκB/NF-κB pathway and elevated inflammatory cytokines levels in liver after exposure for 50 days. After BDE-209 stopping exposure 50 days, the severity of liver damage, ferroptosis and inflammatory response were still higher than the corresponding control group. In vitro, ferroptosis inhibitor Fer-1 rescued ferroptotic damage and attenuated cell death in BDE-209-treated HepG2 and L02 cells. In addition, Fer-1 reversed the activation of IKK/IκB/NF-κB pathway and the increase of pro-inflammatory cytokines levels in BDE-209-treated HepG2 and L02 cells. Together, the above results suggested that BDE-209 induced tissue damage and inflammatory response by activating ferroptosis through increasing iron-dependent lipid peroxidation and blocking the activation of SLC7A11/GSH/GPX4 pathway in liver, indicating that ferroptosis is a potential mechanism for BDE-209-induced hepatotoxicity.

Metabolism toxicity and susceptibility of decabromodiphenyl ether (BDE-209) exposure on BRL cells with insulin resistance

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by insulin resistance (IR) and has attracted worldwide attention due to its high prevalence. As a typical persistent organic pollutant, decabromodiphenyl ether (BDE-209) has been detected in food and human samples, and the concentration trends increase year by year. In addition, it has been proved to have the potential to increase the risk of IR, but it is rarely reported whether it could aggravate IR in T2DM. Therefore, in this study, the IR-BRL (buffalo rat liver cells with IR) model was applied to study the metabolism toxicity and susceptibility of BDE-209. Results showed that BDE-209 could inhibit glucose absorption and increase the levels of serum total cholesterol (TC) and triglyceride (TG), ultimately leading to the disorder of glucolipid metabolism in IR-BRL cells. Besides, it also could cause cell damage by increasing the levels of aspartate transaminase (AST), alanine aminotransferase (ALT), and malondialdehyde (MDA) in cells. Moreover, its potential mechanisms were to: (1) affect the transport of glucose, synthesis of glycogen and fatty acid via IRS-1/GLUT4 and IRS-1/PI3K/AKT/GSK-3β pathways; (2) impact the proliferation and differentiation by regulating the expression of Mek1/2, Erk1/2, and mTOR proteins and genes. Furthermore, susceptibility analysis showed that there was a significant synergism interaction between IR and BDE-209, which suggested that IR-BRL cells were more susceptible to the metabolism toxicity induced by BDE-209.

Associations between polybrominated diphenyl ethers (PBDEs) levels in adipose tissues and blood lipids in women of Shantou, China

Animal studies have indicated that exposure to polybrominated diphenyl ethers (PBDEs) during development can permanently affect blood/liver lipid balance. However, no epidemiological study has assessed the relationship between PBDEs in adipose tissues and blood lipid metabolism. In this study, we explored the associations between PBDEs levels in female adipose tissues and lipid profiles. We recruited 150 female patients undergoing plastic surgery from hospital in Shantou, China, collected their characteristics, clinical information, and adipose tissue samples. Fourteen PBDE congeners in adipose tissues were analyzed by gas chromatography-mass spectrometry (GC-MS). Multiple linear and logistic regression models were used to explore the relationships between PBDEs and lipid profiles, while restricted cubic spline (RCS) regression and Bayesian kernel machine regression (BKMR) models were used to evaluate the nonlinearity of mixtures. Median levels of ΣPBDEs and dominant congeners BDE-153, -209, and -183 in adipose tissues were 73.91, 26.12, 14.10 and 9.01 ng/g lipid, respectively. In the multiple linear model, BDE-153 and BDE-209 were negatively associated with triglycerides (TG), similarly for BDE-190 and total cholesterol (TC). While in the adjusted logistic models, BDE-138 was negatively associated with TC (OR = 0.76, 95%CI: 0.58, 0.99) and total lipids (TL) (OR = 0.76, 95%CI: 0.58, 0.99). Diastolic blood pressure was positively correlated with BDE-28 and BDE-71 (P < 0.05). Furthermore, a non-linear relationship was observed in BDE-138 and blood lipid levels using a RCS model (P_nonlinearity<0.05). BKMR analysis indicated that with the cumulative levels across PBDEs increased, the health risks of hypertriglyceridemia gradually rebounded, and the health risks of hypercholesterolemia and high total lipid gradually rebounded and then declined, but without statistical significance. PBDEs pollution was still prevalent in Shantou city, and several PBDE congeners were significant risk factors for dyslipidemia and blood pressure alteration. There exist deleterious effects of PBDEs and blood lipids.

Association of prenatal exposure to polybrominated diphenyl ethers at low levels with adiposity measures in children up to 6 years

The effects of prenatal PBDEs exposure, especially at low levels, on childhood obesity are scarce. No previous studies have investigated the effect modification by breastfeeding on the associations of PBDEs exposure with childhood obesity. We aimed to investigate the associations of prenatal PBDEs exposure with adiposity measures in children up to 6 years, and the effect modification by breastfeeding. Participants were mother-child pairs from the Shanghai-Minhang Birth Cohort study. Nine PBDE congeners were assessed in cord blood plasma. We obtained information about child weight (0-6 years), height (0.5-6 years), arm circumference (0-6 years), and waist circumference (0-6 years) at each follow-up visit. Breastfeeding duration was collected when children were aged 1 year and was categorized as short (≤6 months) and adequate (>6 months). Multiple linear regression models were used to examine the associations of PBDE concentrations with adiposity measures of the children at each age. Generalized estimating equation (GEE) models were used to estimate the overall associations of PBDEs exposure with adiposity measures. We examined the effect modification by breastfeeding using stratified analyses and by including interaction terms into GEE models. For boys, there was a general profile of positive associations of several PBDE congeners exposure with adiposity measures. Especially, boys with higher BDE-153 concentration had higher adiposity measures at each time point. For girls, we also found positive associations of BDE-100 and -153 exposure with adiposity measures. The GEE models showed consistent patterns for BDE-153 in boys and for BDE-100 and -153 in girls. In breastfeeding-stratified analyses, stronger associations of PBDEs exposure with adiposity measures were generally found in children who were shortly breastfed. Our findings suggest that prenatal exposure to PBDEs at low levels may influence childhood adiposity measures, and the potential effects of PBDEs were attenuated by adequate breastfeeding.

Fat mass and obesity-associated gene (FTO) hypermethylation induced by decabromodiphenyl ethane causing cardiac dysfunction via glucolipid metabolism disorder

Decabromodiphenyl ethane (DBDPE) is a major alternative to BDE-209 owing to its lower toxicity. However, the mass production and increased consumption of DBDPE in recent years have raised concerns related to its adverse health effects. However, the effect and mechanism of DBDPE on cardiotoxicity have rarely been studied. In the present study, we investigated the impacts of DBDPE on the cardiovascular system in male SD rats and then explored the underlying mechanisms to explain the cardiotoxicity of DBDPE using AC16 cells. Under in vivo conditions, male rats were administered with an oral dosage of DBDPE at 0, 5, 50, and 500 mg/kg/day for 28 days, respectively. Histopathological analysis demonstrated that DBDPE induced cardiomyocyte injury and fibrosis, and ultrastructural observation revealed that DBDPE could induce mitochondria damage and dissolution. DBDPE could thus decrease the level of MYH6 and increase the level of SERCA2, which are the two key proteins involved in the maintenance of homeostasis during myocardial contractile and diastolic processes. Furthermore, DBDPE could increase the serum levels of glucose and low-density lipoprotein but decrease the content of high-density lipoprotein. In addition, DBDPE could activate the PI3K/AKT/GLUT2 and PPARγ/RXRα signaling pathways in AC16 cells. In addition, DBDPE decreased the UCP2 level and ATP synthesis in mitochondria both under in vitro and in vivo conditions, consequently leading to apoptosis via the Cytochrome C/Caspase-9/Caspase-3 pathway. Bisulfite sequencing PCR (BSP) identified the hypermethylation status of fat mass and obesity-associated gene (FTO). 5-aza exerted the opposite effects on the PI3K/AKT/GLUT2, PPARγ/RXRα, and Cytochrome C/Caspase-9/Caspase-3 signaling pathways induced by DBDPE in AC16 cells. In addition, the DBDPE-treated altered levels of UCP2, ATP, and apoptosis were also found to be significantly reversed by 5-aza in AC16 cells. These results suggested that FTO hypermethylation played a regulative role in the pathological process of DBDPE-induced glycolipid metabolism disorder, thereby contributing to the dysfunction of myocardial contraction and relaxation through cardiomyocytes fibrosis and apoptosis via the mitochondrial-mediated apoptotic pathway resulting from mitochondrial dysfunction.

Decabromodiphenyl ether-induced PRKACA hypermethylation contributed to glycolipid metabolism disorder via regulating PKA/AMPK pathway in rat and L-02 cells

BDE-209 is the most prevalent congener of polybrominated diphenyl ethers and has high bioaccumulation in humans and animals. BDE-209 has been reported to disrupt glycolipid metabolism, but the mechanisms are still unclear. In this study, we found that BDE-209 induced liver tissue injury and hepatotoxicity, increased the glucose and total cholesterol levels in the serum of rats, and increased glucose and triglyceride levels in L-02 cells. BDE-209 exposure changed the PKA, p-PKA, AMPK, p-AMPK, ACC, and FAS expression in rats' liver and L-02 cells. Moreover, BDE-209 induced PRKACA-1 hypermethylation in L-02 cells. AMPK activator (AICAR) inhibited the changes of p-AMPK, ACC, and FAS expression and elevation of glucose and triglyceride levels induced by BDE-209. DNA methylation inhibitor (5-Aza-CdR) reversed BDE-209 induced alters of PKA/AMPK/ACC/FAS signaling pathway. These results demonstrated that BDE-209 could disrupt the glycolipid metabolism by causing PRKACA-1 hypermethylation to regulate the PKA/AMPK signaling pathway in hepatocytes.

Flame Retardants-Mediated Interferon Signaling in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a growing concern worldwide, affecting 25% of the global population. NAFLD is a multifactorial disease with a broad spectrum of pathology includes steatosis, which gradually progresses to a more severe condition such as nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and eventually leads to hepatic cancer. Several risk factors, including exposure to environmental toxicants, are involved in the development and progression of NAFLD. Environmental factors may promote the development and progression of NAFLD by various biological alterations, including mitochondrial dysfunction, reactive oxygen species production, nuclear receptors dysregulation, and interference in inflammatory and immune-mediated signaling. Moreover, environmental contaminants can influence immune responses by impairing the immune system’s components and, ultimately, disease susceptibility. Flame retardants (FRs) are anthropogenic chemicals or mixtures that are being used to inhibit or delay the spread of fire. FRs have been employed in several household and outdoor products; therefore, human exposure is unavoidable. In this review, we summarized the potential mechanisms of FRs-associated immune and inflammatory signaling and their possible contribution to the development and progression of NAFLD, with an emphasis on FRs-mediated interferon signaling. Knowledge gaps are identified, and emerging pharmacotherapeutic molecules targeting the immune and inflammatory signaling for NAFLD are also discussed.

Decabromodiphenyl ether disturbs hepatic glycolipid metabolism by regulating the PI3K/AKT/GLUT4 and mTOR/PPARγ/RXRα pathway in mice and L02 cells

Decabromodiphenyl ether (BDE-209) is a persistent environmental pollutant that poses great risks to human health and has been associated with glucose and lipid metabolism. However, the mechanisms by which BDE-209 disturbs glycolipid metabolism in the liver remain unclear. Therefore, this study sought to confirm the effects of BDE-209 on glycolipid metabolism in mice livers and L02 cells to elucidate potential mechanisms of action. In vivo BDE-209 exposure caused histological damage and lipid accumulation, elevated glucose, low-density lipoprotein, total cholesterol, and triglyceride levels, and decreased glycogen and high-density lipoprotein levels in mice livers. Moreover, in vitro BDE-209 exposure not only induced L02 cells cytotoxicity (i.e., reduced cell viability and increased LDH leakage and ROS generation) but also increased glucose and triglyceride concentrations in L02 cells. Furthermore, IGF-1, an activator of the PI3K-AKT pathway, markedly inhibited BDE-209-induced glucose concentration increase in L02 cells and antagonized the inhibitory effect of BDE-209 on the PI3K/AKT/GLUT4 pathway by counteracting the changes in the expression levels of p-IRS, AKT, PI3K, p-AKT, and GLUT4. Moreover, GW9662, a PPARγ inhibitor, blocked lipid accumulation and the upregulation of the mTOR/PPARγ/RXRα pathway in L02 cells induced by BDE-209 by relieving the increases in p-mTOR, PPARγ, and RXRα protein expression levels. In summary, this study revealed that BDE-209 disrupted glycolipid metabolism by inhibiting the PI3K/AKT/GLUT4 pathway and activating the mTOR/PPARγ/RXRα pathway.

Polybrominated diphenyl ethers in serum from residents living in a brominated flame retardant production area: Occurrence, influencing factors, and relationships with thyroid and liver function

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants (FRs) in China for decades, even after they were identified as persistent organic pollutants. In this study, serum samples were collected from 172 adults without occupational exposure who were residents of a well-known FR production region (Laizhou Bay, north China), and PBDE congeners were measured to assess their occurrence, congener profile and influencing factors in serum. Moreover, the relationships between serum concentrations of PBDEs and thyroid/liver function indicators were analyzed to evaluate whether human exposure to PBDEs would lead to thyroid/liver injury. All 8 PBDE congeners were detected at higher frequencies and serum concentrations than those found in general populations. The median levels of ∑PBDEs, BDE-209 and ∑_3-7PBDEs (sum of tri-to hepta-BDEs) were 64.5, 56.9 and 7.2 ng/g lw (lipid weight), respectively, which indicated that deca-BDE was the primarily produced PBDE in Laizhou Bay and that the lower brominated BDEs were still ubiquitous in the environment. Gender was a primary influencing factor for some BDE congeners in serum; their levels in female serum samples were significantly lower than those in male serum samples. Serum PBDE levels showed a downward trend with increased body mass index (BMI), which might reflect the increasing serum lipid contents. Serum levels of some BDE congeners were significantly positively correlated with certain thyroid hormones and antibodies, including free triiodothyronine (fT3), total triiodothyronine (tT3), total thyroxine (tT4) and thyroid peroxidase antibody (TPO-Ab). Levels of some congeners were significantly negatively correlated with some types of serum lipid, including cholesterol (CHOL), low density lipoprotein (LDL) and total triglyceride (TG). Other than serum lipids, only two liver function indicators, total protein (TP) and direct bilirubin (DBIL), were significantly correlated with certain BDE congeners (BDE-100 and BDE-154). Our results provide new evidence on the thyroid-disrupting and hepatotoxic effects of PBDEs.

Serum levels of novel brominated flame retardants (NBFRs) in residents of a major BFR-producing region: Occurrence, impact factors and the relationship to thyroid and liver function

Five currently used novel brominated flame retardants (NBFRs) were determined in 172 serum samples collected from nonoccupational residents of a major BFR-producing region. All the 5 NBFRs presented high detection frequencies (DFs, >90%), and decabromodiphenyl ethane (DBDPE), a substitute of decabrominated diphenyl ethers (deca-BDE), was the most abundant NBFR. The levels of DBDPE were from <LOD to 1590 ng/g lw, with a median level of 32.5 ng/g lw. The median levels of other NBFRs were from 0.134 to 2.87 ng/g lw, which were at least 10 times lower than that of DBDPE. Moreover, a comparison to other studies showed that our results were significantly higher than studies conducted in background population. The levels of some NBFRs adjusted by serum lipid showed negative and significant correlation with BMI, whereas the difference disappeared when NBFRs levels were calculated based on serum volume. Certain NBFRs in female showed significantly higher concentrations than those in male. No significant effect of age, smoking habit, education level and children birth (in female) on serum NBFR levels was observed. The relationship between the serum levels of NBFRs and a series of thyroid/liver injury biomarkers was further analyzed to evaluate the health effects of these NBFRs to human being. Results showed that a 10-fold increment in the serum DBDPE level was associated with decreased total triiodothyronine (TT3) level (-0.037 nmol/L) [95% CI: -0.070, -0.003]， whereas serum pentabromoethylbenzene (PBEB) level was associated with increased total triiodothyronine (TT3) level (0.031 nmol/L) [95% CI: 0.001, 0.060]. For liver indicators, a 10-fold increment in the serum level of PBT was associated with decreased Ln aspartate aminotransferase/alanine aminotransferase (AST/ALT) level (-0.068) [95% CI: -0.129, -0.007]. A 10-fold increment in the serum level of BTBPE was associated with increased TBIL level (0.869 μmol/L) [95% CI: 0.175, 1.564], direct bilirubin (DBIL) level (0.231 μmol/L) [95% CI: 0.075, 0.388] and IDBIL level (0.638 μmol/L) [95% CI: 0.091, 1.185]. Our findings indicate that BFR production is posing heavy BFR contamination to surrounding environment and human being, and which might relate to thyroid disruption and liver injury.

Oral exposure to BDE-209 modulates metastatic spread of melanoma in C57BL/6 mice inoculated with B16-F10 cells

Polybrominated diphenyl ethers (PBDEs) are brominated, persistent and bioaccumulative flame retardants widely used in the manufacture of plastic products. Decabromodiphenyl ether (BDE-209) is the most prevalent PBDE in the atmosphere and found in human blood, breast milk and umbilical cord. In vitro studies showed that BDE-209 interferes with murine melanoma cells (B16F10), modulating cell death rates, proliferation and migration, important events for cancer progression. In order to evaluate if BDE-209 modulates metastasis formation in murine models, C57BL/6 mice were exposed to BDE-209 (0.08, 0.8 and 8 μg⁄kg) via gavage (5-day intervals for 45 days) (9 doses in total). Then, mice were inoculated with melanoma cells (B16-F10) at caudal vein receiving 4 additional doses of BDE-209. At 20th day post-cell inoculation, blood, lung, liver, kidney and brain were sampled for hematological, biochemical and morphological analyses. The slightly higher levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the blood and pro-oxidant state in the liver of BDE-exposed mice indicated liver damage. Although the in vivo approach is for metastasis formation in the lung, they were unexpectedly observed in non-target organs (liver, brain, kidney and gonads). The similarity test showed high proximity among individuals from the control and a dissimilarity index between the control and exposed groups. The present data corroborate the known hepatotoxicity of BDE-209 to mice (C57BL/6) and demonstrate for the first time the increase of metastatic dissemination of B16F10 cells in vivo due to previous and continuous BDE-209 exposure, revealing possible implications of this organic compound with melanoma malignancy related traits.

Polybrominated diphenyl ethers and decabromodiphenyl ethane in paired hair/serum and nail/serum from corresponding chemical manufacturing workers and their correlations to thyroid hormones, liver and kidney injury markers

We detected the polybrominated diphenyl ethers (PBDEs) or decabromodiphenyl ethane (DBDPE) in paired hair-serum and nail-serum samples collected from the corresponding chemical manufacturing workers. The levels of decabrominated diphenyl ether (BDE-209) or DBDPE in the serum, hair and nail samples were all significantly higher than those reported in other studies, and the "work place" (pretreatment or posttreatment workshop) was the primary influencing factor that affected the levels of specific BFRs in vivo. For BDE-209 workers, the BDE-209 in both the hair and nail samples were significantly and positively related to the BDE-209 in the serum, indicating that both hair and nails can be used as noninvasive biomatrices to reflect internal exposure to BDE-209. In DBDPE workers, hair rather than nails was more suitable for use as a noninvasive biomatrix to infer the DBDPE exposure level. A series of serum biomarkers reflecting thyroid hormones and liver and kidney injuries were tested to calculate the correlations between hair or nail BFR levels and the levels of the biomatrices. The BDE-209 in the hair samples was significantly and positively correlated with the total protein (TP), and the nail BDE-209 level was significantly and positively related to the total bilirubin (TBIL), indirect bilirubin (IDBIL) and uric acid (UA). The DBDPE in hair was significantly and positively correlated with the thyroid hormones free triiodothyronine (fT3) and total triiodothyronine (tT3) and kidney injury markers, including blood urea nitrogen (BUN), creatinine (CRE) and cystatin C (Cys-C). In addition, the nail DBDPE levels were significantly and positively correlated with the albumin/globulin (A/G), BUN, CRE and Cys-C but negatively correlated with the TP and globulin (GLO). Our findings provide preliminary evidence that hair and nails can be used as noninvasive biomatrices for assessing internal BFR exposure and health damage in occupational workers.

Autophagy role in environmental pollutants exposure

During the last decades, the potential harmfulness derived from the exposure to environmental pollutants has been largely demonstrated, with associated damages ranging from geno- and cyto-toxicity to tissue malfunction and alterations in organism physiology. Autophagy is an evolutionarily-conserved cellular mechanism essential for cellular homeostasis, which contributes to protect cells from a wide variety of intracellular and extracellular stressors. Due to its pivotal importance, its correct functioning is directly linked to cell, tissue and organismal fitness. Environmental pollutants, particularly industrial compounds, are able to impact autophagic flux, either by increasing it as a protective response, by blocking it, or by switching its protective role toward a pro-cell death mechanism. Thus, the understanding of the effects of chemicals exposure on autophagy has become highly relevant, offering new potential approaches for risk assessment, protection and preventive measures to counteract the detrimental effects of environmental pollutants on human health.

Hepatotoxicity of decabromodiphenyl ethane (DBDPE) and decabromodiphenyl ether (BDE-209) in 28-day exposed Sprague-Dawley rats

Decabromodiphenyl ether (BDE-209) and its substitute decabromodiphenyl ethane (DBDPE) are heavily used in various industrial products as flame retardant. They have been found to be persistent in the environment and have adverse health effects in humans. Although some former studies have reported toxic effects of BDE-209, the study of DBDPE's toxic effects is still in its infancy, and the effects of DBDPE on hepatotoxicity are also unclear. This study aimed to evaluate and compare the hepatotoxicity induced by BDE-209 and DBDPE using a rat model. Sprague-Dawley rats were administered DBDPE or BDE-209 (5, 50, 500 mg/kg bodyweight) intragastrically once a day for 28 days. Twenty-four hours after the end of treatment, the rats were sacrificed, and body liver weight, blood biochemical parameters, liver pathology, oxidative stress, inflammation, pregnane X receptor (PXR), constitutive androstane receptor (CAR), and changes in cytochrome P450 (CYP3A) enzymes were measured. Our results showed that both BDE-209 and DBDPE could cause liver morphological changes, induce oxidative stress, increase γ-glutamyl transferase and glucose levels in serum, and down-regulate PXR, CAR, and CYP3A expression. In addition, BDE-209 was found to increase liver weight and the ratio of liver/body weight, lead to elevated total bilirubin and indirect bilirubin levels in serum, and induce inflammation. The present study indicated that BDE-209 and DBDPE may interfere with normal metabolism in rats through oxidative stress and inflammation, which inhibit PXR and CAR to induce the expression of CYP3A enzymes, and finally produce hepatotoxic effects and cause liver damage in rats. Comparatively, our results show that the damage caused by BDE-209 was more serious than that caused by DBDPE.