Association of blood polychlorinated biphenyls and cholesterol levels among Canadian Inuit

Polychlorinated biphenyls and incident coronary heart disease-related outcomes in Great Lakes fish consumers

BACKGROUND

Exposure to polychlorinated biphenyls (PCBs) has been linked to risk factors for cardiovascular disease such as increased inflammation, accelerated atherosclerosis, diabetes, and sex hormone dysregulation. Furthermore, there is increasing evidence suggesting associations between internal dose of PCBs and cardiovascular outcomes.

OBJECTIVES

The purpose of this study is to investigate longitudinal associations of PCBs with coronary heart disease (CHD)-related outcomes in a cohort of Great Lakes sport fish consumers.

METHODS

The Great Lakes Sport Fish Consumer cohort was established in the early 1990's. Eight hundred nineteen participants were followed from 1993 to 2017. Serum PCBs were measured in 1994/1995 (baseline), in 2001, and in 2004, while health history questionnaires were administered in 1996, 2003, 2010, and 2017. Cox models were used to prospectively investigate associations of total PCBs and PCB groupings, based on aryl hydrocarbon receptor activity, with incident self-reported physician diagnosis of coronary heart disease (CHD), myocardial infarction (MI), and angina pectoris.

RESULTS

A 2-fold increase in phenobarbital-type PCBs was associated with a 72% increase in likelihood of self-reported incident diagnosis of CHD (HR=1.72, 95% CI: 1.06-2.81; p=0.0294). Similar results were observed for total PCBs (HR=1.68, 95% CI: 1.05-2.69; p=0.0306) and mixed methacholine/phenobarbital type (mixed-type) PCBs (HR=1.60, 95% CI: 1.02-2.52; p=0.0427), but not methacholine-type PCBs. PCBs were not strongly associated with risk of MI or angina.

CONCLUSIONS

This study presents evidence that exposure to PCBs increases the risk of developing coronary heart disease. Given the large number of risk factors and causal pathways for CHD, future research is required to better understand biological mechanisms of action for PCBs on CHD.

The association of exposure to polychlorinated biphenyls with lipid profile and liver enzymes in umbilical cord blood samples

Evidence on prenatal exposure to polychlorinated biphenyls (PCBs) and its effects on newborns and potential biological mechanisms is not well defined yet. Therefore, this study aimed to examine whether PCBs are associated with lipid profile and non-invasive markers of hepatocyte injuries in samples of blood obtained from the umbilical cord. This study included 450 mothers-newborn pairs. Umbilical levels of PCBs were measured using Gas Chromatography/Mass Spectrophotometry (GC/MS). Lipid profile including low-density lipoprotein (LDL-C), total cholesterol (TC), triglycerides (TG), and high-density lipoprotein (HDL-C), as well as liver enzymes i.e., alanine amino transferase (ALT), aspartate amino transferase (AST), γ-glutamyl-transferase (GGT) and alkaline phosphatase (ALP) were determined from umbilical cord blood samples. Quantile g-computation analysis was applied to evaluate the collective influence of PCBs on both lipid profiles and liver enzymes, along with the impact of lipid profiles on liver enzymes. Exposure to the mixture of PCBs was significantly associated with increases in ALP, AST, ALT, and GGT levels in cord blood samples, with increments of 90.38 U/L (95%CI: 65.08, 115.70, p < 0.01), 11.88 U/L (95%CI: 9.03, 14.74, p < 0.01), 2.19 U/L (95%CI:1.43, 2.94, p < 0.01), and 50.67 U/L (95%CI: 36.32, 65.03, p < 0.01), respectively. Additionally, combined PCBs exposure was correlated with significant increases in umbilical TG, TC, and LDL-C levels, with values of 3.97 mg/dL (95%CI: 0.86, 7.09, p = 0.01), 6.30 mg/dL (95%CI: 2.98, 9.61, p < 0.01), and 4.63 mg/dL (95%CI: 2.04, 7.23, p < 0.01) respectively. Exposure to the mixture of lipids was linked to elevated levels of AST and GGT in umbilical cord blood samples. Furthermore, a noteworthy mediating role of TC and LDL-C was observed in the association between total PCBs exposure and umbilical cord blood liver enzyme levels. Overall our findings suggested that higher levels of umbilical cord blood PCBs and lipid profile could affect liver function in newborns.

Metabolome-wide association study of four groups of persistent organic pollutants and abnormal blood lipids

Environmental exposure increases the risk of dyslipidemia, which affects human health. Research has shown that persistent organic pollutants (POPs), including per- and polyfluoroalkyl substances (PFASs), polychlorinated biphenyls, polybrominated diphenyl ethers, and phthalate metabolites, are associated with a higher risk of abnormal blood lipid levels in humans. However, the key molecules involved in dyslipidemia and the mechanisms are not fully understood. This study aims to investigate the biomarkers that mediate the relationships between blood lipids and four groups of POPs and revealed their potential mechanisms. Specifically, in 278 male blood samples, blood lipid and POPs levels were measured and metabolites were detected using untargeted metabolomics. Spearman's correlation analysis and binary logistic regression were employed to assess the relationship between POPs and lipid indexes. We observed that PFASs were associated with a higher risk of abnormal total cholesterol (TC) and low-density lipoprotein (LDL), while other POPs displayed little association with abnormal lipid indexes. Among all the PFASs, 6:2Cl-PFESA was associated with the fewest metabolites. A metabolome-wide association study combined with a meet-in-the-middle approach was used to identify potential biomarkers that mediate the association between POPs and abnormal blood lipids. The mediation analysis pointed to 105 significant mediators as potential biomarkers mediating the association between PFASs and TC, and 82 significant mediators were potential biomarkers that mediated the association between PFASs and LDL. 24-Hydroxycholesterol, 3alpha,7alpha-dihydroxy-5beta-cholestan-26-al, PC(18:0/0:0), PC(22:5/0:0), GPCho(18:1/18:1), LysoPC(22:2(13Z,16Z)), LysoPC(16:0), 9(S)-HODE, 9,10-DHOME, l-glutamate, 4-hydroxybutyric acid, cytosine, PC(14:1(9Z)/18:0), sphinganine, and (S)-beta-aminoisobutyrate were identified as important biomarkers. The mechanism may mainly involves glycerophospholipid metabolism, primary bile acid biosynthesis, and linoleic acid metabolism. PPARγ likely plays a role in the associations between PFASs and abnormal cholesterol metabolism. Overall, our study provides clues for the early detection of PFAS-induced dyslipidemia and brings forth a theoretical framework for further research into this mechanism.

Exposure to PCB126 during the nursing period reversibly impacts early-life glucose tolerance

Polychlorinated biphenyls (PCBs) are persistent environmental organic pollutants known to have detrimental health effects. Using a mouse model, we previously demonstrated that PCB126 exposure before and during pregnancy and throughout the perinatal period adversely affected offspring glucose tolerance and/or body composition profiles. The purpose of this study was to investigate the glucose tolerance and body composition of offspring born to dams exposed to PCB126 during the nursing period only. Female ICR mice were bred, and half of the dams were exposed to either vehicle (safflower oil) or 1 µmole PCB126 per kg of body weight via oral gavage on postnatal days (PND) 3, 10, and 17 (n = 9 per group). Offspring body weight, lean and fat mass, and glucose tolerance were recorded every three weeks. PCB126 treatment did not alter dam nor offspring body weight (p > 0.05). PCB126-exposed male and female offspring displayed normal body composition (p > 0.05) relative to vehicle-exposed offspring. However, both male and female offspring that were exposed to PCB126 during the nursing period had significantly impaired glucose tolerance at 3 and 9 weeks of age (p < 0.05). At 6 and 12 weeks of age, no impairments in glucose tolerance existed in offspring (p > 0.05). Our current study demonstrates that exposure to PCB126 through the mother's milk does not affect short- or long-term body composition but impairs glucose tolerance in the short-term.

Metabolism of 3-Chlorobiphenyl (PCB 2) in a Human-Relevant Cell Line: Evidence of Dechlorinated Metabolites

Lower chlorinated polychlorinated biphenyls (LC-PCBs) and their metabolites make up a class of environmental pollutants implicated in a range of adverse outcomes in humans; however, the metabolism of LC-PCBs in human models has received little attention. Here we characterize the metabolism of PCB 2 (3-chlorobiphenyl), an environmentally relevant LC-PCB congener, in HepG2 cells with in silico prediction and nontarget high-resolution mass spectrometry. Twenty PCB 2 metabolites belonging to 13 metabolite classes, including five dechlorinated metabolite classes, were identified in the cell culture media from HepG2 cells exposed for 24 h to 10 μM or 3.6 nM PCB 2. The PCB 2 metabolite profiles differed from the monochlorinated metabolite profiles identified in samples from an earlier study with PCB 11 (3,3'-dichlorobiphenyl) under identical experimental conditions. A dechlorinated dihydroxylated metabolite was also detected in human liver microsomal incubations with monohydroxylated PCB 2 metabolites but not PCB 2. These findings demonstrate that the metabolism of LC-PCBs in human-relevant models involves the formation of dechlorination products. In addition, untargeted metabolomic analyses revealed an altered bile acid biosynthesis in HepG2 cells. Our results indicate the need to study the disposition and toxicity of complex PCB 2 metabolites, including novel dechlorinated metabolites, in human-relevant models.

Geographic and Ethnic Variations in Serum Concentrations of Legacy Persistent Organic Pollutants among Men in the Nenets Autonomous Okrug, Arctic Russia

The overwhelming majority of Arctic biomonitoring studies in humans include either pregnant or non-pregnant women of reproductive age while little attention is paid to toxic compounds concentrations in men. This study contributes with information of the present amounts of persistent organic pollutants (POPs) in men living in Arctic Russia. We studied the serum concentrations of 11 polychlorinated biphenyl (PCB) congeners and 17 organochlorine pesticides (OCPs) and some of their metabolites in samples collected from 92 adult men (mean age 43 years) from seven different settlements in Nenets Autonomous Okrug (NAO). The median concentrations of individual PCB congeners increased in the order PCB 183, PCB 180, PCB 118, PCB 138, PCB 153. The concentrations of o, p′-DDD, p, p′-DDD, aldrin, mirex and 1,2,3,5-TCB were in most cases below the quantification limit. The observed concentrations of PCBs and chlorinated pesticides were in the same range as those found in similar groups of women of these territories, but lower than of men in other Arctic countries. However, significant geographic differences between the settlements were observed with exceptionally high concentrations of PCBs in the Islands group. The highest serum ∑PCBs and β-HCH levels were observed in adult males aged 60–78 years. We found significant variations in serum concentrations of POPs across settlements and ethnic groups with exceptionally high concentrations of PCBs among the residents of the Arctic islands. At the same time, our findings suggest a considerable decrease in serum concentration of POPs over the last decade.

Lack of Offspring Nrf2 Does Not Exacerbate the Detrimental Metabolic Outcomes Caused by In Utero PCB126 Exposure

Human environmental exposures to toxicants, such as polychlorinated biphenyls (PCBs), increase oxidative stress and disease susceptibility. Such exposures during pregnancy and/or nursing have been demonstrated to adversely affect offspring health outcomes. Nuclear factor erythroid-2-related factor 2 (Nrf2) regulates the antioxidant response and is involved in the detoxification of coplanar PCBs, like PCB126. The purpose of this study was to investigate glucose tolerance and body composition in PCB-exposed offspring expressing or lacking Nrf2. We hypothesized that offspring lacking Nrf2 expression would be more susceptible to the long-term health detriments associated with perinatal PCB exposure. During gestation, whole-body Nrf2 heterozygous (Het) and whole-body Nrf2 knockout (KO) mice were exposed to vehicle or PCB126. Shortly after birth, litters were cross-fostered to unexposed dams to prevent PCB exposure during nursing. Offspring were weaned, and their body weight, body composition, and glucose tolerance were recorded. At two months of age, PCB exposure resulted in a significant reduction in the average body weight of offspring born to Nrf2 Het dams (p < 0.001) that primarily arose from the decrease in average lean body mass in offspring (p < 0.001). There were no differences in average body weight of PCB-exposed offspring born to Nrf2 KO dams (p > 0.05), and this was because offspring of Nrf2 KO dams exposed to PCB126 during pregnancy experienced a significant elevation in fat mass (p = 0.002) that offset the significant reduction in average lean mass (p < 0.001). Regardless, the lack of Nrf2 expression in the offspring themselves did not enhance the differences observed. After an oral glucose challenge, PCB-exposed offspring exhibited significant impairments in glucose disposal and uptake (p < 0.05). Offspring born to Nrf2 Het dams exhibited these impairments at 30 min and 120 min, while offspring born to Nrf2 KO dams exhibited these impairments at zero, 15, 30, 60 and 120 min after the glucose challenge. Again, the interactions between offspring genotype and PCB exposure were not significant. These findings were largely consistent as the offspring reached four months of age and demonstrate that the lack of offspring Nrf2 expression does not worsen the metabolic derangements caused by in utero PCB exposure as we expected. Future directions will focus on understanding how the observed maternal Nrf2 genotypic differences can influence offspring metabolic responses to in utero PCB exposure.

Maternal folic acid supplementation does not counteract the deleterious impact of prenatal exposure to environmental pollutants on lipid homeostasis in male rat descendants

Prenatal exposure to persistent organic pollutants (POPs) has been associated with the development of metabolic syndrome-related diseases in offspring. According to epidemiological studies, father’s transmission of environmental effects in addition to mother’s can influence offspring health. Moreover, maternal prenatal dietary folic acid (FA) may beneficially impact offspring health. The objective is to investigate whether prenatal FA supplementation can overcome the deleterious effects of prenatal exposure to POPs on lipid homeostasis and inflammation in three generations of male rat descendants through the paternal lineage. Female Sprague-Dawley rats (F0) were exposed to a POPs mixture (or corn oil) +/− FA supplementation for 9 weeks before and during gestation. F1 and F2 males were mated with untreated females. Plasma and hepatic lipids were measured in F1, F2, and F3 males after 12-h fast. Gene expression of inflammatory cytokines was determined by qPCR in epididymal adipose tissue. In F1 males, prenatal POPs exposure increased plasma lipids at 14 weeks old and hepatic lipids at 28 weeks old and prenatal FA supplementation decreased plasma total cholesterol at 14 weeks old. Prenatal POPs exposure decreased plasma triglycerides at 14 weeks old in F2 males. No change was observed in inflammatory markers. Our results show an impact of the paternal lineage on lipid homeostasis in rats up to the F2 male generation. FA supplementation of the F0 diet, regardless of POPs exposure, lowered plasma cholesterol in F1 males but failed to attenuate the deleterious effects of prenatal POPs exposure on plasma and hepatic lipids in F1 males.

Effects of cross-fostering and developmental exposure to mixtures of environmental contaminants on hepatic gene expression in prepubertal 21 days old and adult male Sprague-Dawley rats

The notion that adverse health effects produced by exposure to environmental contaminants (EC) may be modulated by the presence of non-chemical stressors is gaining attention. Previously, our lab demonstrated that cross-fostering (adoption of a litter at birth) acted as a non-chemical stressor that amplified the influence of developmental exposure to EC on the glucocorticoid stress-response in adult rats. Using liver from the same rats, the aim of the current study was to investigate whether cross-fostering might also modulate EC-induced alterations in hepatic gene expression profiles. During pregnancy and nursing, Sprague-Dawley dams were fed cookies laced with corn oil (control, C) or a chemical mixture (M) composed of polychlorinated biphenyls (PCB), organochlorine pesticides (OCP), and methylmercury (MeHg), at 1 mg/kg/day. This mixture simulated the contaminant profile reported in maternal human blood. At birth, some control and M treated litters were cross-fostered to form two additional groups with different biological/nursing mothers (CC and MM). The hepatic transcriptome was analyzed by DNA microarray in male offspring at postnatal days 21 and 78-86. Mixture exposure altered the expression of detoxification and energy metabolism genes in both age groups, but with different sets of genes affected at day 21 and 78-86. Cross-fostering modulated the effects of M on gene expression pattern (MM vs M), as well as expression of energy metabolism genes between control groups (CC vs C). In conclusion, while describing short and long-term effects of developmental exposure to EC on hepatic transcriptomes, these cross-fostering results further support the consideration of non-chemical stressors in EC risk assessments.

Organochlorine pesticides and polychlorinated biphenyls (PCBs) in early adulthood and blood lipids over a 23-year follow-up

BACKGROUND

Some evidence in humans suggests that persistent organic pollutants (POPs), including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), may alter the blood lipid composition. This study analyzed associations between serum POPs concentrations in young adulthood with blood lipid levels up to 23 years later.

METHODS

Serum POPs were measured in year 2 of follow-up (n = 180 men and women, ages: 20-32y), and plasma lipids in follow-up years 2, 7, 10, 15, 20 and 25. 32 POPs were detectable in ≥75% of participants (23 PCBs, 8 OCPs and PBB-153). We created summary scores for PCBs and OCPs for both wet-weight, and lipid standardized (LP) concentrations. We used repeated measures regression adjusting for demographic factors, BMI, smoking, diabetes status, among others.

RESULTS

We observed positive associations of the 23 LP-PCB score with total cholesterol (β_{per SD increase} [95%CI]: 5.0 mg/dL [0.7, 9.2]), triglycerides (7.8 mg/dL [-0.9, 16.5]), LDL (4.2 mg/dL [0.2, 8.2]), oxidized LDL 3.4 U/L (-0.05, 6.8), and cholesterol/HDL ratio (0.2 [0.02, 0.3]). The associations for triglycerides (14.7 mg/dL [0.4, 20.1]), cholesterol/HDL (0.33 [0.09, 0.56]) and, to some extent, LDL (4.7 md/dL [-1.6, 10.9]) were only observed among participants in the upper 50th percentile of BMI. Non-dioxin-like PCBs had stronger associations that dioxin-like PCBs. OCPs and PBB-s had positive associations with most outcomes.

CONCLUSIONS

PCBs and PBB-153 measured in young adulthood were positively associated with prospective alterations in most blood lipid components, with evidence of effect modification by BMI. Further longitudinal studies with multiple measures of POPs overtime are needed.

Decarbromodiphenyl ether (BDE-209) promotes monocyte-endothelial adhesion in cultured human aortic endothelial cells through upregulating intercellular adhesion molecule-1

There is growing evidence that exposure to persistent organic pollutants (POPs) is statistically associated with incidence of cardiovascular disease (CVD) or its risk factors. Decarbromodiphenyl ether (BDE-209) is a new POP which exists extensively in human tissues, but its potential effects on CVD have so far received less focus. The adhesion of circulating monocytes to endothelial cells is one of the critical underlying steps in the initiation and development of CVD. In the present study, we investigated the effect of BDE-209 on the adhesion of THP-1 monocytes to human aortic endothelial cells (HAECs) and identified the molecular mechanisms involved. Our results showed that 6.25, 12.5 and 25 µM of BDE-209 exposures caused significant increases in monocyte-endothelial cell adhesion, in a dose-dependent manner. Mechanistically, BDE-209 exposure increased the expression of intercellular adhesion molecule-1 (ICAM-1). Moreover, the up-regulation of ICAM-1 was accompanied by a decrease in the expression of microRNA-141 (miR-141). Furthermore, the up-regulation of ICAM-1 and the increased adhesion induced by BDE-209 could be reversed by miR-141 supplement. Taken together, our results show that BDE-209 potentiates monocyte-endothelial cell interaction via miR-141/ICAM-1 pathway in HAECs.

Associations of multiple exposures to persistent toxic substances with the risk of hyperuricemia and subclinical uric acid levels in BIOAMBIENT.ES study

Hyperuricemia is becoming a serious public health issue, which is highly influenced by environmental factors, although there is still controversial information on the potential influence of the exposure to Persistent Toxic Substances (PTSs) in the general population. In this study we aimed to assess the association. PTS exposure with uric acid homeostasis in a sample of the Spanish population. Participants were recruited during 2009-2010 in all the main geographical areas of Spain. Exposure to 34 PTSs was estimated by chemical analyses of serum levels of 6 Polychlorinated Biphenyls (PCBs, n = 950), 13 Organochlorine Pesticides (OCPs, n = 453), 6 Perfluoroalkyl Substances (PFAs, n = 755), 7 Polybrominated Diphenyl Ethers (PBDEs, n = 365), urinary Cadmium (n = 926), and Lead in whole blood (n = 882). The two study outcomes were defined as the prevalence of hyperuricemia in the study population and uric acid levels, the latter only in individuals with no previous diagnosis of hyperuricemia. Statistical analyses were performed by means of binomial logistic regression and linear regression, and mixture effects were screened using Weighted Quantile Sum Regression (WQS). Serum concentrations of γ-HCH, o,p´-DDE, PCB-138, PCB-153, PFOA, and urinary Cadmium were associated with an increased risk of hyperuricemia, while PBDE-153 showed an inverse association with the effect. Furthermore, exposure to Cadmium, PCB-138, and to PCB-153 was positively associated with uric acid levels. Results were consistent after lipid adjustment or standardization. WQS analyses revealed a major contribution of PCB-153 within the PCB mixture on both the risk of hyperuricemia and uric acid levels. Sensitivity analyses were performed by adjusting for dietary habits, fasting glucose and estimated glomerular filtration rate. Overall, we found novel associations between human exposure to mixtures of PTSs and disturbances in uric acid homeostasis. However, we cannot completely rule out potential residual confounding effect or reversed-causality related to the cross-sectional design.

MicroRNA-21 attenuates BDE-209-induced lipid accumulation in THP-1 macrophages by downregulating Toll-like receptor 4 expression

Growing evidence demonstrates a possible response of specific microRNA (miRNA) to environmental pollutant stimuli in multiple biological processes. We previously reported that a persistent organic pollutant, decabromodiphenyl ether (BDE-209), can enhance Toll-like receptor 4 (TLR4)-dependent lipid uptake in THP-1 macrophages; whether miRNAs are involved in this process remains unclear. In the present study, we investigated the levels of several miRNAs related to TLR4 signaling, including miRs-9, -21, -27b, -125b, -132, -146a, -147, -155, and -let-7e, in THP-1 macrophages after stimulation by BDE-209 and oxidized low-density lipoprotein. The results showed that the levels of miR-21 were significantly suppressed by BDE-209 at concentrations of 6.25, 12.5 and 25 μM, in a dose-dependent manner; whereas there was no significant changes for the other miRNAs investigated. Moreover, the suppression of miR-21 was accompanied by an upregulated TLR4 expression, at both mRNA and protein levels. Further analysis showed that the up-regulated TLR4 induced by BDE-209 was inhibited in macrophages transfected with miR-21 mimic; meanwhile opposite results were exhibited when an anti-miR-21 inhibitor was transfected to the macrophages. Additionally, transfection with miR-21 mimic effectively attenuated BDE-209-induced lipid accumulation in macrophages. Together, these data illustrate that miR-21 inhibits BDE-209-triggered lipid accumulation in macrophages through down-regulating TLR4 expression.

Identification of candidate biomarkers of the exposure to PCBs in contaminated cattle: A gene expression- and proteomic-based approach

Dioxins and polychlorinated biphenyls (PCBs) are widespread and persistent contaminants. Through a combined gene expression/proteomic-based approach, candidate biomarkers of the exposure to such environmental pollutants in cattle subjected to a real eco-contamination event were identified. Animals were removed from the polluted area and fed a standard ration for 6 months. The decontamination was monitored by evaluating dioxin and PCB levels in pericaudal fat two weeks after the removal from the contaminated area (day 0) and then bimonthly for six months (days 59, 125 and 188). Gene expression measurements demonstrated that CYP1B1 expression was significantly higher in blood lymphocytes collected in contaminated animals (day 0), and decreased over time during decontamination. mRNA levels of interleukin 2 showed an opposite quantitative trend. MALDI-TOF-MS polypeptide profiling of serum samples ascertained a progressive decrease (from day 0 to 188) of serum levels of fibrinogen β-chain and serpin A3-7-like fragments, apolipoprotein (APO) C-II and serum amyloid A-4 protein, along with an augmented representation of transthyretin isoforms, as well as APOC-III and APOA-II proteins during decontamination. When differentially represented species were combined with serum antioxidant, acute phase and proinflammatory protein levels already ascertained in the same animals (Cigliano et al., 2016), bioinformatics unveiled an interaction network linking together almost all components. This suggests the occurrence of a complex PCB-responsive mechanism associated with animal contamination/decontamination, including a cohort of protein/polypeptide species involved in blood redox homeostasis, inflammation and lipid transport. All together, these results suggest the use in combination of such biomarkers for identifying PCB-contaminated animals, and for monitoring the restoring of their healthy condition following a decontamination process.

Decabromodiphenyl ether (BDE-209) enhances foam cell formation in human macrophages via augmenting Toll-like receptor 4-dependent lipid uptake

Growing epidemiological evidence is substantiating an association between exposure to persistent organic pollutants (POPs) and incidence of atherosclerosis. Decabromodiphenyl ether (BDE-209) is a new POP which presents extensively in human populations; whether this contaminant is potentially arteriosclerotic remains unclear. In this study, we investigated the effects of BDE-209 on macrophage-derived foam cell formation, a hallmark of early atherosclerosis, using THP-1-derived macrophages incubated with oxidized low-density lipoprotein (oxLDL) as a foam cell model. The results showed that 6.25, 12.5 and 25.0 μM of BDE-209 significantly enhanced lipid accumulation inside the foam cells, in a dose-dependent manner. Further mechanism assays suggested that BDE-209 significantly increased the expression of Toll-like receptor 4 (TLR4), a signal transducing integral membrane protein mediating lipid uptake in macrophages, at both the mRNA and protein levels. In contrast, there was no significant changes for several key regulators involving in lipid efflux, lipogenesis, and lipid oxidation in macrophages. Furthermore, the augmented lipid accumulation was almost completely abrogated by treatment with an anti-TLR4 antibody. Together, these data illustrate that BDE-209 enhances oxLDL-induced macrophage foam cell formation via augmenting TLR4-dependent lipid uptake in the cells.

Effects of biometrics, location and persistent organic pollutants on blood clinical-chemical parameters in polar bears (Ursus maritimus) from Svalbard, Norway

In the present study, blood clinical-chemical parameters (BCCPs) were analysed in 20 female and 18 male Svalbard polar bears (Ursus maritimus) captured in spring 2007. The aim was to study how age, body condition (BC), biometrics, plasma lipid content and geographical location may confound the relationship between persistent organic pollutants (POPs) including PCBs, HCB, chlordanes, DDTs, HCHs, mirex and OH-PCBs and the concentrations of 12 specific BCCPs (hematocrit [HCT], hemoglobin [HB], aspartate aminotransferase [ASAT], alanine aminotransferase [ALAT], γ-glutamyltransferase [GGT], creatine kinase [CK], triglycerides [TG], cholesterol [CHOL], high-density lipoprotein [HDL], creatinine (CREA], urea, potassium (K]), and to investigate if any of these BCCPs may be applied as potential biomarkers for POP exposure in polar bears. Initial PCA and O-PLS modelling showed that age, lipids, BC and geographical location (longitude and latitude) were important parameters explaining BCCPs in females. Following subsequent partial correlation analyses correcting for age and lipids, multiple POPs in females were still significantly correlated with HCT and HDL (all p < 0.05). In males, age, BM, BC and longitude were important parameters explaining BCCPs. Following partial correlation analyses correcting for age, biometrics, lipids and longitude in males, multiple POPs were significantly correlated with HCT, ASAT, GGT and CHOL (all p < 0.05). In conclusion, several confounding parameters has to be taken into account when studying the relations between BCCPs and POPs in polar bears. When correcting for these, in particular HCT may be used as a simple cost-efficient biomarker of POP exposure in polar bears. Furthermore, decreasing HDL concentrations and increasing CHOL concentration with increasing POP concentrations may indicate responses related to increased risk of cardiovascular disease. We therefore suggest to further study POP exposure and lipidome response to increase knowledge of the risk of cardiometabolic syndrome in polar bears.