RESUMO
Perfluorooctane sulfonate (PFOS) is a persistent environmental chemical whose biological effects are mediated by multiple mechanisms. Recent evidence suggests that the gut microbiome may be directly impacted by and/or alter the fate and effects of environmental chemicals in the host. Thus, the aim of this study was to determine whether PFOS influences the gut microbiome and its metabolism, and the host metabolome. Four groups of male C57BL/6 J mice were fed a diet with or without 0.003 %, 0.006 %, or 0.012 % PFOS, respectively. 16S rRNA gene sequencing, metabolomic, and molecular analyses were used to examine the gut microbiota of mice after dietary PFOS exposure. Dietary PFOS exposure caused a marked change in the gut microbiome compared to controls. Dietary PFOS also caused dose-dependent changes in hepatic metabolic pathways including those involved in lipid metabolism, oxidative stress, inflammation, TCA cycle, glucose, and amino acid metabolism. Changes in the metabolome correlated with changes in genes that regulate these pathways. Integrative analyses also demonstrated a strong correlation between the alterations in microbiota composition and host metabolic profiles induced by PFOS. Further, using isolated mouse cecal contents, PFOS exposure directly affected the gut microbiota metabolism. Results from these studies demonstrate that the molecular and biochemical changes induced by PFOS are mediated in part by the gut microbiome, which alters gene expression and the host metabolome in mice.
Assuntos
Ácidos Alcanossulfônicos/toxicidade , Fluorocarbonos/toxicidade , Microbioma Gastrointestinal/efeitos dos fármacos , Animais , Ceco/efeitos dos fármacos , Ceco/metabolismo , Ceco/microbiologia , Dieta , Relação Dose-Resposta a Droga , Homeostase/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Metaboloma , Metabolômica , Camundongos , Camundongos Endogâmicos C57BL , RNA Ribossômico 16S/biossíntese , RNA Ribossômico 16S/genéticaRESUMO
Potassium perfluorohexanesulfonate (K+PFHxS) was evaluated for reproductive/developmental toxicity in CD-1 mice. Up to 3â¯mg/kg-dâ¯K+PFHxS was administered (nâ¯=â¯30/sex/group) before mating, for at least 42â¯days in F0 males, and for F0 females, through gestation and lactation. F1 pups were directly dosed with K+PFHxS for 14â¯days after weaning. There was an equivocal decrease in live litter size at 1 and 3â¯mg/kg-d, but the pup-born-to-implant ratio was unaffected. Adaptive hepatocellular hypertrophy was observed, and in 3â¯mg/kg-d F0 males, it was accompanied by concomitant decreased serum cholesterol and increased alkaline phosphatase. There were no other toxicologically significant findings on reproductive parameters, hematology/clinical pathology/TSH, neurobehavioral effects, or histopathology. There were no treatment-related effects on postnatal survival, development, or onset of preputial separation or vaginal opening in F1 mice. Consistent with previous studies, our data suggest that the potency of PFHxS is much lower than PFOS in rodents.
Assuntos
Efeitos Tardios da Exposição Pré-Natal , Ácidos Sulfônicos/toxicidade , Fosfatase Alcalina/sangue , Animais , Colesterol/sangue , Feminino , Fluorocarbonos , Hepatócitos/efeitos dos fármacos , Hepatócitos/patologia , Masculino , Troca Materno-Fetal , Camundongos Endogâmicos ICR , GravidezRESUMO
Perfluorooctane sulfonate (PFOS) is an environmentally persistent chemical. Dietary 100 ppm PFOS fed to male mice and rats for 4 weeks caused hepatic steatosis through an unknown mechanism. Choline deficient diets can cause hepatic steatosis. A hepatic choline:PFOS ion complex was hypothesized to cause this effect in mice. This study tested whether dietary choline supplementation attenuates PFOS-induced hepatic steatosis in rats. Sprague Dawley rats (12/sex/group) were fed control, choline supplemented (CS), 100 ppm PFOS, or 100 ppm PFOS + CS diets for 3 weeks. Male rats fed both PFOS-containing diets had decreased serum cholesterol and triglycerides (TGs) on days 9, 16, and/or 23 and increased hepatic free fatty acids and TG (ie, steatosis). Female rats fed both PFOS diets had decreased serum cholesterol on days 9 and 16 and decreased hepatic free fatty acid and TG at termination (ie, no steatosis). Liver PFOS concentrations were similar for both sexes. Liver choline concentrations were increased in male rats fed PFOS (±CS), but the increase was lower in the PFOS + CS group. Female liver choline concentrations were not altered by any diet. These findings demonstrate a clear sex-related difference in PFOS-induced hepatic steatosis in the rat. Additional evaluated mechanisms (ie, nuclear receptor activation, mRNA upregulation, and choline kinase activity inhibition) did not appear to be involved in the hepatic steatosis. Dietary PFOS (100 ppm) induced hepatic steatosis in male, but not female, rats that was not attenuated by choline supplementation. The mechanism of lipid accumulation and the sex-related differences warrant further investigation.
Assuntos
Ácidos Alcanossulfônicos/toxicidade , Colina/administração & dosagem , Suplementos Nutricionais , Poluentes Ambientais/toxicidade , Fluorocarbonos/toxicidade , Fígado/efeitos dos fármacos , Hepatopatia Gordurosa não Alcoólica/induzido quimicamente , Hepatopatia Gordurosa não Alcoólica/prevenção & controle , Animais , Biomarcadores/sangue , Colesterol/sangue , Ácidos Graxos não Esterificados/metabolismo , Feminino , Regulação da Expressão Gênica , Fígado/metabolismo , Fígado/patologia , Masculino , Hepatopatia Gordurosa não Alcoólica/sangue , Hepatopatia Gordurosa não Alcoólica/genética , Tamanho do Órgão , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Sprague-Dawley , Fatores Sexuais , Fatores de Tempo , Triglicerídeos/sangueRESUMO
Choline is an essential nutrient utilized for phosphatidylcholine biosynthesis and lipoprotein packaging and secretion. Recently, choline supplementation has been used by athletes and the public for weight loss. However, the potential toxicological impact of choline dietary supplementation requires further investigation. This study examined the effects of choline dietary supplementation in Sprague Dawley rats for 4 weeks. Rats were fed diets containing basal choline levels (control) or 5-, 10-, or 15-fold (5×, 10×, or 15×) basal diet concentration. In groups fed choline-supplemented diets, there were no toxicologically relevant findings in clinical observations, food intake, clinical chemistry, liver weights, or liver histopathology. However, decreased mean body weights (8.5-10.2%) and body weight gains (24-31%) were noted for the 10× choline-supplemented (females only) and 15× choline-supplemented (both sexes) groups relative to the control groups from day 3 onward. These body weight effects were not related to a persistent reduction in average food intake. Serum cholesterol was increased in the 15× choline-supplemented male rats relative to the controls, an expected effect of choline supplementation; however, there were no changes in the serum cholesterol of female rats. Serum choline concentrations were increased in female rats relative to the male rats across all treatment groups. The maximum tolerated dose for male and female rats were the 15× and 10× choline supplements, respectively, based on decreased mean body weight and body weight gains. This study supported the conclusions of a clinical trial that showed a high choline diet can decrease body weight in humans.
Assuntos
Colina/farmacologia , Suplementos Nutricionais , Redução de Peso/efeitos dos fármacos , Animais , Colina/administração & dosagem , Colina/sangue , Ingestão de Alimentos/efeitos dos fármacos , Feminino , Fígado/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Perfluorooctane sulfonyl fluoride (POSF) was a volatile starting material in the production of perfluorooctane sulfonate (PFOS), a stable surfactant that has been extensively studied due to its ubiquitous environmental distribution and slow clearance in humans. Because the inhalation toxicity of POSF on repeated exposure has not been previously reported, the current study evaluated the inhalation toxicity of POSF at 30, 100, and 300ppm (v/v) in rats for up to 13 weeks with a four-week recovery period. The extent of PFOS formation was also measured because POSF hydrolyzed to form PFOS. In addition, detailed urinalysis and examination of the urinary bladder were included to determine if factors associated with the development of bladder cancer were present. Exposure to POSF at 300ppm was associated with reduction in body weight-gain, necrosis of laryngeal cartilage, increased lung and bronchi weight with septal thickening, and changes in alveolar macrophages. The microscopic observations in larynx and lung are consistent with likely hydrolysis of POSF to form hydrogen fluoride (HF). Exposure to POSF at 100 and 300ppm was associated with increased relative liver weight, hepatocellular hypertrophy (except for females exposed to 100ppm POSF), and lowering of serum cholesterol (male only). After 13 weeks of exposure to 30, 100, or 300ppm POSF, serum PFOS concentration approximated 7, 35, or 100µg/mL, respectively. Approximately 0.1% of inhaled POSF was converted to PFOS. No changes indicative of bladder effects were observed in these rats exposed to POSF at any dose.
Assuntos
Poluentes Ambientais/toxicidade , Fluorocarbonos/química , Fluorocarbonos/toxicidade , Exposição por Inalação , Ácidos Alcanossulfônicos/metabolismo , Ácidos Alcanossulfônicos/toxicidade , Animais , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/patologia , Colesterol/sangue , Ingestão de Alimentos/efeitos dos fármacos , Poluentes Ambientais/sangue , Poluentes Ambientais/farmacocinética , Poluentes Ambientais/urina , Feminino , Fluorocarbonos/sangue , Fluorocarbonos/metabolismo , Fluorocarbonos/farmacocinética , Fluorocarbonos/urina , Ácido Fluorídrico/metabolismo , Ácido Fluorídrico/toxicidade , Hidrólise , Hipertrofia , Cartilagens Laríngeas/efeitos dos fármacos , Cartilagens Laríngeas/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Pulmão/efeitos dos fármacos , Pulmão/patologia , Macrófagos Alveolares/efeitos dos fármacos , Macrófagos Alveolares/patologia , Masculino , Necrose , Tamanho do Órgão , Ratos Sprague-Dawley , Medição de Risco , Fatores de Tempo , Testes de Toxicidade , Aumento de Peso/efeitos dos fármacosRESUMO
Ethyl-N-(2-hydroxyethyl)-perfluorooctanesulfonamide (EtFOSE) was one of the key building blocks for many of the perfluorooctanesulfonyl-based chemistry and laboratory studies have shown that EtFOSE can metabolically degrade to perfluorooctanesulfonate (PFOS). Non-occupational contribution sources to PFOS are thought to occur in general population via diets, drinking water, air and dust. For workers, however, the exposure route was mostly airborne and the exposure source was predominantly to precursor compounds such as EtFOSE. We undertook this study to investigate how much EtFOSE was converted to PFOS in the serum for male rats after 6h of exposure to EtFOSE vapor (whole body) at ambient temperature, which simulated a work place exposure scenario. There were no abnormal clinical observations and all rats gained weight during study. Interim tail-vein blood samples, collected up to 21 days after exposure, were analyzed for Et-FOSE and PFOS concentrations by LC-MS/MS. Upon inhalation exposure, the biotransformation of EtFOSE to PFOS in serum in the male rats was rapid and very little EtFOSE was detected in the serum within 24h after EtFOSE exposure. The highest conversion to PFOS in serum after exposure to EtFOSE vapor appeared to occur between Day 8-14 post exposure. Considering the potential surface and fur adsorption of test compound in the whole-body exposure system, our data would support that at least 10% of the inhaled EtFOSE was biotransformed to PFOS in the serum based on the range of lower 95% CI (confidence interval) values. This information is valuable because it quantitatively translates EtFOSE exposure into serum PFOS concentration, which serves as a matrix for internal dosimetry (of PFOS exposure) that can be used as an anchor across species as well as between different exposure routes.
Assuntos
Ácidos Alcanossulfônicos/sangue , Fluorocarbonos/sangue , Sulfonamidas/farmacocinética , Administração por Inalação , Animais , Biotransformação , Masculino , Ratos Sprague-DawleyRESUMO
An oral dose study with perfluorooctanesulfonate (PFOS) was undertaken to identify potential associations between serum PFOS and changes in serum clinical chemistry parameters in purpose-bred young adult cynomolgus monkeys (Macaca fascicularis). In this study, control group (n = 6/sex) was sham-dosed with vehicle (0.5% Tween 20 and 5% ethanol in water), low-dose group (n = 6/sex) received 1 single K+PFOS dose (9 mg/kg), and high-dose group (n = 4-6/sex) received 3 separate K+ PFOS doses (11-17.2 mg/kg). Monkeys were given routine checkups and observed carefully for health problems on a daily basis. Scheduled blood samples were drawn from all monkeys prior to, during, and after K+PFOS administration for up to 1 year and they were analyzed for PFOS concentrations and clinical chemistry markers for coagulation, lipids, hepatic, renal, electrolytes, and thyroid-related hormones. No mortality occurred during the study. All the monkeys were healthy, gained weight, and were released back to the colony at the end of the study. The highest serum PFOS achieved was approximately 165 µg/ml. When compared with time-matched controls, administration of K+PFOS to monkeys did not result in any toxicologically meaningful or clinically relevant changes in serum clinical measurements for coagulation, lipids, hepatic, renal, electrolytes, and thyroid-related hormones. A slight reduction in serum cholesterol (primarily the high-density lipoprotein fraction), although not toxicologically significant, was observed. The corresponding lower-bound fifth percentile benchmark concentrations (BMCL1sd) were 74 and 76 µg/ml for male and female monkeys, respectively. Compared to the 2013-2014 geometric mean serum PFOS level of 4.99 ng/ml (0.00499 µg/ml) in US general population reported by CDC NHANES, this represents 4 orders of magnitude for margin of exposure.
Assuntos
Ácidos Alcanossulfônicos/sangue , Ácidos Alcanossulfônicos/toxicidade , Fluorocarbonos/sangue , Fluorocarbonos/toxicidade , Lipídeos/sangue , Fígado/efeitos dos fármacos , Hormônios Tireóideos/sangue , Animais , Coagulação Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , HDL-Colesterol/sangue , Relação Dose-Resposta a Droga , Feminino , Fígado/metabolismo , Macaca fascicularis , MasculinoRESUMO
Perfluoroalkyl sulfonates (PFSAs) such as perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonate (PFOS) have very long serum elimination half-lives in humans, and preferentially distribute to serum and liver. The enterohepatic circulation of PFHxS and PFOS likely contributes to their extended elimination half-lives. We previously demonstrated that perfluorobutane sulfonate (PFBS), PFHxS, and PFOS are transported into hepatocytes both in a sodium-dependent and a sodium-independent manner. We identified Na+/taurocholate cotransporting polypeptide (NTCP) as the responsible sodium-dependent transporter. Furthermore, we demonstrated that the human apical sodium-dependent bile salt transporter (ASBT) contributes to the intestinal reabsorption of PFOS. However, so far no sodium-independent uptake transporters for PFSAs have been identified in human hepatocytes or enterocytes. In addition, perfluoroalkyl carboxylates (PFCAs) with 8 and 9 carbons were shown to preferentially distribute to the liver of rodents; however, no rat or human liver uptake transporters are known to transport these PFCAs. Therefore, we tested whether PFBS, PFHxS, PFOS, and PFCAs with 7-10 carbons are substrates of organic anion transporting polypeptides (OATPs). We used CHO and HEK293 cells to demonstrate that human OATP1B1, OATP1B3, and OATP2B1 can transport PFBS, PFHxS, PFOS, and the 2 PFCAs (C8 and C9). In addition, we show that rat OATP1A1, OATP1A5, OATP1B2, and OATP2B1 transport all 3 PFSAs. In conclusion, our results suggest that besides NTCP and ASBT, OATPs also are capable of contributing to the enterohepatic circulation and extended human serum elimination half-lives of the tested perfluoroalkyl acids.
Assuntos
Ácidos Alcanossulfônicos/metabolismo , Poluentes Ambientais/metabolismo , Fluorocarbonos/metabolismo , Hepatócitos/metabolismo , Transportador 1 de Ânion Orgânico Específico do Fígado/metabolismo , Transportadores de Ânions Orgânicos/metabolismo , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/metabolismo , Animais , Transporte Biológico , Células CHO , Caprilatos/metabolismo , Cricetulus , Células HEK293 , Humanos , Transportador 1 de Ânion Orgânico Específico do Fígado/genética , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos Sódio-Independentes/genética , Transportadores de Ânions Orgânicos Sódio-Independentes/metabolismo , Ratos , Proteínas Recombinantes de Fusão/metabolismo , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/genética , Ácidos Sulfônicos/metabolismoRESUMO
The mechanisms underlying perfluorooctane sulfonate (PFOS)-induced steatosis remain unclear. The hypothesis that PFOS causes steatosis and other hepatic effects by forming an ion pair with choline was examined. C57BL/6 mice were fed either a control diet or a marginal methionine/choline-deficient (mMCD) diet, with and without 0.003, 0.006, or 0.012% potassium PFOS. Dietary PFOS caused a dose-dependent decrease in body weight, and increases in the relative liver weight, hepatic triglyceride concentration and serum markers of liver toxicity and oxidative stress. Some of these effects were exacerbated in mice fed the mMCD diet supplemented with 0.012% PFOS compared with those fed the control diet supplemented with 0.012% PFOS. Surprisingly, serum PFOS concentrations were higher while liver PFOS concentrations were lower in mMCD-fed mice compared with corresponding control-fed mice. To determine if supplemental dietary choline could prevent PFOS-induced hepatic effects, C57BL/6 mice were fed a control diet, or a choline supplemental diet (1.2%) with or without 0.003% PFOS. Lipidomic analysis demonstrated that PFOS caused alterations in hepatic lipid metabolism in the PFOS-fed mice compared with controls, and supplemental dietary choline prevented these PFOS-induced changes. Interestingly, dietary choline supplementation also prevented PFOS-induced oxidative damage. These studies are the first to suggest that PFOS may cause hepatic steatosis and oxidative stress by effectively reducing the choline required for hepatic VLDL production and export by forming an ion pair with choline, and suggest that choline supplementation may prevent and/or treat PFOS-induced hepatic steatosis and oxidative stress.
Assuntos
Ácidos Alcanossulfônicos/metabolismo , Colina/metabolismo , Fígado Gorduroso/induzido quimicamente , Fluorocarbonos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ácidos Alcanossulfônicos/toxicidade , Animais , Colina/toxicidade , Relação Dose-Resposta a Droga , Fluorocarbonos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Among the perfluoroalkyl sulfonates (PFASs), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) have half-lives of several years in humans, mainly due to slow renal clearance and potential hepatic accumulation. Both compounds undergo enterohepatic circulation. To determine whether transporters involved in the enterohepatic circulation of bile acids are also involved in the disposition of PFASs, uptake of perfluorobutane sulfonate (PFBS), PFHxS, and PFOS was measured using freshly isolated human and rat hepatocytes in the absence or presence of sodium. The results demonstrated sodium-dependent uptake for all 3 PFASs. Given that the Na(+)/taurocholate cotransporting polypeptide (NTCP) and the apical sodium-dependent bile salt transporter (ASBT) are essential for the enterohepatic circulation of bile acids, transport of PFASs was investigated in stable CHO Flp-In cells for human NTCP or HEK293 cells transiently expressing rat NTCP, human ASBT, and rat ASBT. The results demonstrated that both human and rat NTCP can transport PFBS, PFHxS, and PFOS. Kinetics with human NTCP revealed Km values of 39.6, 112, and 130 µM for PFBS, PFHxS, and PFOS, respectively. For rat NTCP Km values were 76.2 and 294 µM for PFBS and PFHxS, respectively. Only PFOS was transported by human ASBT whereas rat ASBT did not transport any of the tested PFASs. Human OSTα/ß was also able to transport all 3 PFASs. In conclusion, these results suggest that the long half-live and the hepatic accumulation of PFOS in humans are at least, in part, due to transport by NTCP and ASBT.
Assuntos
Ácidos Alcanossulfônicos/farmacocinética , Fluorocarbonos/farmacocinética , Transportadores de Ânions Orgânicos Dependentes de Sódio/fisiologia , Ácidos Sulfônicos/farmacocinética , Simportadores/fisiologia , Animais , Hepatócitos/metabolismo , Humanos , RatosRESUMO
Previous studies suggested that perfluorooctanoate (PFOA) could activate the estrogen receptor (ER). The present study examined the hypothesis that PFOA can activate ER using an in vivo uterotrophic assay in CD-1 mice and an in vitro reporter assay. Pre-pubertal female CD-1 mice fed an estrogen-free diet from postnatal day (PND)14 through weaning on PND18 were administered 0, 0.005, 0.01, 0.02, 0.05, 0.1, or 1mg/kg PFOA or 17ß-estradiol (E2, 0.5mg/kg) from PND18-20. In contrast to E2, PFOA caused no changes in the relative uterine weight, the expression of ER target genes, or the morphology of the uterus/cervix and/or vagina on PND21. Treatment of a stable human cell line containing an ER-dependent luciferase reporter construct with a broad concentration range of PFOA caused no change in ER-dependent luciferase activity; whereas E2 caused a marked increase of ER-dependent luciferase activity. These data indicate that PFOA does not activate mouse or human ER.
Assuntos
Caprilatos/toxicidade , Poluentes Ambientais/toxicidade , Fluorocarbonos/toxicidade , Receptores de Estrogênio/efeitos dos fármacos , Útero/efeitos dos fármacos , Vagina/efeitos dos fármacos , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Estradiol/farmacologia , Receptor alfa de Estrogênio/efeitos dos fármacos , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Estrogênios/farmacologia , Feminino , Regulação da Expressão Gênica , Genes Reporter , Humanos , Camundongos , Tamanho do Órgão , Receptores de Estrogênio/genética , Receptores de Estrogênio/metabolismo , Elementos de Resposta , Transfecção , Útero/metabolismo , Útero/patologia , Vagina/metabolismo , Vagina/patologiaRESUMO
Two chronic dietary studies, conducted years apart, with ammonium perfluorooctanoate (APFO) in Sprague Dawley rats have been previously reported. Although both included male 300 ppm dietary dose groups, only the later study, conducted in 1990-1992 by Biegel et al., reported an increase in proliferative lesions (hyperplasia and adenoma) of the acinar pancreas. An assessment of the significance of the differences between both studies requires careful consideration of: the diagnostic criteria for proliferative acinar cell lesions of the rat pancreas (for example, the diagnosis of pancreatic acinar cell hyperplasia versus adenoma is based on the two-dimensional size of the lesion rather than distinct morphological differences); the basis for those criteria in light of their relevance to biological behavior; and the potential diagnostic variability between individual pathologists for difficult-to-classify lesions. A pathology peer review of male exocrine pancreatic tissues from the earlier study, conducted in 1981-1983 by Butenhoff et al., was undertaken. This review identified an increase in acinar cell hyperplasia but not adenoma or carcinoma in the earlier study. Both studies observed a proliferative response in the acinar pancreas which was more pronounced in the study by Biegel et al. Definitive reasons for the greater incidence of proliferative lesions in the later study were not identified, but some possible explanations are presented herein. The relevance of this finding to human risk assessment, in the face of differences in the biological behavior of human and rat pancreatic proliferative lesions and the proposed mechanism of formation of these lesions, are questionable.
RESUMO
Perfluorooctanoate (PFOA) is a fully fluorinated eight-carbon fatty acid analog with exceptional stability toward degradation that has been used as an industrial surfactant and has been detected in environmental and biological matrices. Exposures to PFOA in the workplace and in the environment have continuously stimulated investigations into its potential human health hazards. In this article, the results of fifteen unpublished genotoxicity assays conducted with perfluorooctanoate (as either the linear or linear/branched ammonium salt (APFO) or the linear/branched sodium salt) are reported and include: seven mutation assays (three in vitro reverse mutation assays with histidine auxotrophic strains of Salmonella typhimurium, two in vitro reverse mutation assays with the tryptophan auxotrophic Escherichia coli WP2uvr strain, one in vitro mitotic recombination (gene conversion) assay with Saccharomyces cerevisiae D4, and an in vitro Chinese hamster ovary (CHO) HGPRT forward mutation assay); seven studies to assess potential for chromosomal damage (three in vitro CHO chromosomal aberration studies, an in vitro human whole blood lymphocyte chromosomal aberration study, and three in vivo mouse micronucleus assays); and an in vitro C3H 10T1/2 cell transformation assay. Although PFOA has not been demonstrated to be metabolized, all in vitro assays were conducted both in the presence and in the absence of a mammalian hepatic microsomal activation system. These assays were originally described in twelve contract laboratory reports which have been available via the United States Environmental Protection Agency public docket (Administrative Record 226) for over a decade; however, the details of these assays have not been published previously in the open scientific literature. With the exception of limited positive findings at high and cytotoxic concentrations in some assay trials which reflected the likely consequence of cytotoxic disruption of normal cellular processes and not a specific genotoxic effect, the results of the studies presented in this paper and other published results clearly demonstrate the absence of direct mutagenic or genotoxic risk associated with PFOA. This finding is consistent with the physical/chemical characteristics of PFOA and is supported by other published genotoxicity studies.
RESUMO
This study examined the effect of prenatal perfluorooctanoic acid (PFOA) administration on pre- and postnatal development using peroxisome proliferator-activated receptor α (PPARα)-humanized mice to determine if species differences in receptor activity might influence the developmental effects induced by PFOA. Pregnant mice were treated daily with water or PFOA (3mg/kg) by po gavage from gestation day 1 (GD1) until GD17 and then either euthanized on GD18 or allowed to give birth and then euthanized on postnatal day 20 (PND20). No changes in average fetal weight, crown-to-rump length, or placental weight were observed on GD18. Expression of mRNA encoding the PPARα target genes acyl CoA oxidase (Acox1) and cytochrome P450 4a10 (Cyp4a10) in maternal and fetal liver was increased on GD18 in wild-type and PPARα-humanized mice but not in Pparα-null mice. On PND20, relative liver weight was higher in wild-type mice but not in Pparα-null mice or PPARα-humanized mice. Hepatic expression of Acox1 and Cyp4a10 mRNA was higher in wild-type mice but not in Pparα-null mice or PPARα-humanized mice on PND20. The percentage of mice surviving postnatally was lower in wild-type litters but not in litters from Pparα-null mice or PPARα-humanized mice. No changes in pup weight gain, onset of eye opening, or mammary gland development were found in any genotype. Results from these studies demonstrate that the developmental/postnatal effects resulting from prenatal PFOA exposure in mice are differentially mediated by mouse and human PPARα.
Assuntos
Caprilatos/toxicidade , Fluorocarbonos/toxicidade , PPAR alfa/metabolismo , Animais , Feminino , Humanos , Camundongos , Camundongos Knockout , Gravidez , Reação em Cadeia da Polimerase em Tempo Real , Especificidade da EspécieRESUMO
OBJECTIVE: To examine in a longitudinal occupational assessment whether changes in serum concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) are associated with changes in non-high-density lipoprotein (HDL) cholesterol. METHODS: Baseline and end-of-project PFOA, PFOS, lipid, and hepatic clinical chemistries were measured in 204 workers involved with the demolition of former perfluoroalkyl manufacturing facilities. Analyses were restricted to the 179 workers who did not take lipid-lowering medications. Two thirds had baseline PFOA and PFOS levels similar to the general population. RESULTS: The change in non-HDL cholesterol was not associated with the changes in PFOA or PFOS. An increase in HDL was associated with an increase in PFOA, although the magnitude was small. This increase in HDL resulted in a decrease in the total cholesterol/HDL ratio. CONCLUSION: Adverse associations were not observed between changes in PFOA, PFOS, non-HDL cholesterol, HDL, and hepatic clinical chemistries.
Assuntos
Ácidos Alcanossulfônicos/sangue , Caprilatos/sangue , VLDL-Colesterol/sangue , Fluorocarbonos/sangue , Lipídeos/sangue , Lipoproteínas HDL/sangue , Exposição Ocupacional , Adulto , Indústria Química , LDL-Colesterol/sangue , Feminino , Humanos , Fígado/metabolismo , Estudos Longitudinais , Masculino , Pessoa de Meia-IdadeRESUMO
In order to assess the potential chronic toxicity and tumorigenicity of ammonium perfluorooctanoate (APFO), a 2-year dietary study was conducted with male and female rats fed 30 ppm or 300 ppm (approximately 1.5 and 15 mg/kg). In males fed 300 ppm, mean body weights were lower across most of the test period and survival in these rats was greater than that seen either in the 30 ppm or the control group. Non-neoplastic effects were observed in liver in rats fed 300 ppm and included elevated liver weight, an increase in the incidence of diffuse hepatocellular hypertrophy, portal mononuclear cell infiltration, and mild hepatocellular vacuolation without an increase in hepatocellular necrosis. Mean serum activities of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were elevated up to three times the control means, primarily at the 300 ppm dose. A significant increase in Leydig cell tumors of the testes was seen in the males fed 300 ppm, and tumors of the liver and acinar pancreas, which are often observed in rats from chronic exposure to peroxisome proliferating agents, were not observed in this study. All other tumor types were those seen spontaneously in rats of this stock and age and were not associated with feeding of APFO.
Assuntos
Caprilatos/toxicidade , Dieta/efeitos adversos , Fluorocarbonos/toxicidade , Animais , Peso Corporal/efeitos dos fármacos , Peso Corporal/fisiologia , Caprilatos/administração & dosagem , Testes de Carcinogenicidade/métodos , Feminino , Fluorocarbonos/administração & dosagem , Fígado/efeitos dos fármacos , Fígado/patologia , Masculino , Tamanho do Órgão/efeitos dos fármacos , Tamanho do Órgão/fisiologia , Ratos , Ratos Sprague-Dawley , Taxa de Sobrevida/tendênciasRESUMO
Some cross-sectional epidemiological studies have reported positive associations of serum concentrations of non-high density lipoprotein cholesterol with serum perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). However, the strength of the reported associations is inconsistent for exposure-response across three orders of magnitude of serum PFOS and/or PFOA concentrations. These positive associations are unexpected based on toxicological/mechanistic studies, suggesting that the associations may have a biological, rather than a causal, basis. This study tested the hypothesis that PFOS and PFOA distribute into serum lipoprotein fractions such that increases in serum lipoproteins would result in corresponding increases in serum concentrations of PFOS and PFOA. Based on observed binding of PFOS and PFOA to isolated ß-lipoproteins in physiological saline (96% and 40% bound, respectively) in preliminary experiments using ultrafiltration and LC-MS/MS methods, binding to human donor plasma lipoprotein fractions was investigated by two density gradient methods. The majority of PFOS and PFOA recovered masses were found in lipoprotein-depleted plasma. Plasma density gradient fractionation data suggested that maximally 9% of PFOS distributes to lipoprotein-containing fractions, yet only 1% or less of PFOA is so distributed. These data do not support a strong role for plasma lipoprotein fractions in explaining the inconsistent dose-response associations reported in cross-sectional epidemiological studies.
Assuntos
Ácidos Alcanossulfônicos/sangue , Caprilatos/sangue , Fluorocarbonos/sangue , Lipoproteínas/sangue , Centrifugação com Gradiente de Concentração , Estudos Transversais , Relação Dose-Resposta a Droga , Humanos , Ligação ProteicaRESUMO
The present study investigated the potential role for activation of PPARα and CAR/PXR by potassium PFOS (K⺠PFOS) with respect to the etiology of hepatic hypertrophy and hepatocellular adenoma in rats. Male Sprague-Dawley rats were fed K⺠PFOS (20 or 100 ppm) for either 1, 7, or 28 days. Wyeth 14,643 (Wy 14,643, 50 ppm) and phenobarbital (PB, 500 ppm) were the controls for PPARα and CAR/PXR activation, respectively. Measurements included: plasma ALT, AST, cholesterol, triglycerides, and glucose; liver protein and DNA content; liver activities of palmitoyl CoA oxidase (ACOX), Cyp4A, CYP2B, and CYP3A; induction of liver CYP4A1, CYP2E1, CYP2B1/2, and CYP3A1 proteins (SDS-PAGE and Western blots); liver and thyroid microscopic histopathology, apoptotic index, and cell proliferation index. Terminal body weight was decreased by K⺠PFOS (100 ppm) and Wy 14,643. All test-compound treatments increased liver weight. Plasma lipids were decreased by both PFOS and Wy 14,643. After treatment for 1 day, K⺠PFOS (100 ppm), PB, and Wy 14,643 increased mean hepatic DNA concentration and total hepatic DNA, and total DNA remained elevated after treatment for 7 days and 28 days (PB and Wy 14,643 only). Hepatic P450 concentration was elevated after 7 and 28 days by K⺠PFOS and by PB. K⺠PFOS and Wy 14,643 increased liver activities of ACOX and CYP4A as well as increased liver CYP4A1 protein. By 28 days of treatment, K⺠PFOS and PB increased liver activities of CYP2B and CYP3A as well as increased liver CYP2B1/2 and CYP3A1 proteins, and Wy 14,643 increased CYP2B enzyme activity to a slight extent. All test compounds increased the liver cell proliferative index and decreased the liver apoptotic index. No histological changes of the thyroid were noted; however, PB and WY increased thyroid follicular cell proliferation index (seven-day treatment only), while K⺠PFOS did not. The thyroid follicular cell apoptotic index did not differ between groups. The hepatomegaly and hepatocellular adenoma observed after dietary exposure of Sprague-Dawley rats to K⺠PFOS likely are due to the increased expression of xenosensor nuclear receptors PPARα and CAR/PXR. Given the markedly lower or absent response of human hepatocytes to the proliferative stimulus from activation of PPARα and CAR/PXR, the hepatocellular proliferative response from activation of these receptors by PFOS observed in rats is not expected to be of human relevance.
Assuntos
Adenoma de Células Hepáticas/induzido quimicamente , Ácidos Alcanossulfônicos/toxicidade , Proliferação de Células/efeitos dos fármacos , Fluorocarbonos/toxicidade , Neoplasias Hepáticas/induzido quimicamente , PPAR alfa/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores de Esteroides/metabolismo , Adenoma de Células Hepáticas/química , Adenoma de Células Hepáticas/metabolismo , Adenoma de Células Hepáticas/patologia , Ácidos Alcanossulfônicos/administração & dosagem , Ácidos Alcanossulfônicos/análise , Ácidos Alcanossulfônicos/farmacocinética , Animais , Apoptose/efeitos dos fármacos , Carcinógenos/administração & dosagem , Carcinógenos/análise , Carcinógenos/farmacocinética , Carcinógenos/toxicidade , Receptor Constitutivo de Androstano , Sistema Enzimático do Citocromo P-450/metabolismo , Relação Dose-Resposta a Droga , Poluentes Ambientais/administração & dosagem , Poluentes Ambientais/análise , Poluentes Ambientais/farmacocinética , Poluentes Ambientais/toxicidade , Fluorocarbonos/administração & dosagem , Fluorocarbonos/análise , Fluorocarbonos/farmacocinética , Hepatomegalia/induzido quimicamente , Fígado/química , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Neoplasias Hepáticas/química , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Masculino , Proteínas de Neoplasias/metabolismo , Receptor de Pregnano X , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Glândula Tireoide/efeitos dos fármacos , Glândula Tireoide/patologia , Testes de Toxicidade SubagudaRESUMO
In a prior 28-day dietary study in rats with 20 and 100 ppm K⺠PFOS, activation of PPARα and CAR/PXR were concluded to be etiological factors in K⺠PFOS-induced hepatomegaly and hepatic tumorigenesis. The objective of this study was to evaluate persistence/resolution of K⺠PFOS-induced, liver-related effects in male Sprague Dawley rats following a 7-day dietary exposure to K⺠PFOS at 20 or 100 ppm. Groups of 10 rats per treatment were observed on recovery Day(s) 1, 28, 56, and 84 following treatment. Changes consistent with hepatic PPARα and CAR/PXR activation noted on recovery Day 1 included: increased liver weight; decreased plasma cholesterol, alanine aminotransferase, and triglycerides; decreased liver DNA concentration and increased hepatocellular cytosolic CYP450 concentration; increased liver activity of acyl CoA oxidase, CYP4A, CYP2B, and CYP3A; increased liver proliferative index and decreased liver apoptotic index; decreased hepatocellular glycogen-induced vacuoles; increased centrilobular hepatocellular hypertrophy. Most effects resolved to control levels during recovery. Effects on plasma cholesterol, hepatocellular cytosolic CYP450 concentrations, liver apoptotic index, CYP3A, and centrilobular hepatocellular hypertrophy persisted through the end of the recovery period. Thyroid parameters (histology, apoptosis, and proliferation) were unaffected at all time points. Mean serum PFOS concentrations on recovery Day 1 were 39 and 140 µg/mL (20 ppm and 100 ppm K⺠PFOS, respectively), decreasing to 4 and 26 µg/mL by recovery Day 84. Thus, hepatic effects in male rats resulting from K⺠PFOS-induced activation of PPARα and CAR/PXR resolved slowly or were still present after 84-days following a 7-day dietary treatment, consistent with the slow elimination rate of PFOS.