Endocrine-disrupting polychlorinated biphenyls in metabolically healthy and unhealthy obese subjects before and after weight loss: difference at the start but not at the finish

Endocrine disrupting chemicals and obesity prevention: scoping review

INTRODUCTION

Exposure to endocrine disrupting chemicals (EDCs) can result in alterations of natural hormones in the body. The aim of this review article is to highlight the knowledge about EDCs and obesity.

METHODS

A scoping review of the electronic literature was performed using PubMed platform for studies on EDCs and obesity published between the years 2013-2023. A total of 10 systematic reviews and meta-analysis studies met our inclusion criteria on more prominent EDCs focusing mainly on bisphenols, including parabens, triclosan, and phthalates, and their association with obesity.

DESIGN

Scoping review.

RESULTS

EDCs, mostly bisphenols and phthalates, are related to health effects, while there is less information on the impact of parabens and triclosan. A series of negative physiological effects involving obesogenic, diabetogenic, carcinogenic, and inflammatory mechanisms as well as epigenetic and microbiota modulations was related to a prolonged EDCs exposure. A more profound research of particular pollutants is required to illuminate the accelerating effects of particular EDCs, mixtures or their metabolites on the mechanism of the development of obesity.

CONCLUSION

Considering the characteristics of EDCs and the heterogeneity of studies, it is necessary to design specific studies of effect tracking and, in particular, education about daily preventive exposure to EDCs for the preservation of long-term public health.

Changes in Adipose Tissue and Circulating Concentrations of Persistent Organic Pollutants in Midlife Women

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) that bioaccumulate in adipose tissue. We investigated the relationship between change in central adiposity and changes in circulating concentrations of POPs over a 12-year period during the midlife. Serum concentrations of 34 PCBs and 19 OCPs were measured at four time points (1999/2000, 2002/03, 2005/06, 2009/11) in a cohort of midlife women, the Study of Women's Health Across the Nation. Linear mixed models were used to test the association between a change in waist circumference and a change in serum POP concentrations. Sixty-five women contributed 181 PCB observations. Fifty-nine women contributed 151 OCP observations. After adjustment for covariates (study site, race and ethnicity, age at baseline, parity), a one-inch (2.54 cm) increase in the change in waist circumference between visits was associated with a 4.9% decrease in the change in serum concentration of PCB 194 (95% CI: -8.0%, -1.6%). No associations were observed for other PCB congeners or the presence of OCPs. An increase in the difference in waist circumference over time was not associated with a change in the difference in serum concentrations of PCBs and OCPs except for PCB 194, possibly due to the high lipophilicity.

Polychlorinated biphenyls and risk of metabolic syndrome and comparison with the risk of diabetes: A systematic review and meta-analysis

With the increasing incidence of metabolic syndrome (MetS) worldwide and no consistent results on PCBs and MetS. A meta-analysis to explore their relationship was conducted. Given the high correlation and overlap of MetS with diabetes, analysis of diabetes risk, was used as a supplement to compare with MetS. Seven studies included MetS, 15 studies for diabetes, and one study included both outcomes. It was found that PCBs may not be a risk factor for MetS, but their high heterogeneity indicates that they are under-represented. In addition, our results showed that total PCBs might be a protective factor against diabetes. In the whole blood subgroup, which can reflect the accumulation of more than one body load, heterogeneity was reduced, and its OR value suggested that PCBs increased the risk of MetS in the whole blood biomaterial. DL-PCBs were positively associated with MetS and diabetes, while NDL-PCBs were negatively associated with diabetes. In the subgroup analysis of PCBs homologs, DL-PCB-126 and DL-PCB-118 were risk factors for MetS and diabetes, respectively. In addition, PCB-153 and 180 showed a dose-response relationship between them and diabetes mellitus, respectively. The results of total analysis of MetS and diabetes mellitus and subgroup analysis of PCBs were mixed, and this reason might be attributed to the different mechanisms of action and effect sizes of different PCBs, so based on subgroup results and in vivo and in vitro experiments, we considered PCBs to be a risk factor for MetS and diabetes. Due to various reasons, there are still many shortcomings in the evaluation of PCBs impact on human health, and more high-quality research are needed to further explore the role of PCBs of different species and congeners in MetS and diabetes.

Cross-sectional associations of persistent organic pollutants measured in adipose tissue and metabolic syndrome in clinically diagnosed middle-aged adults

INTRODUCTION

Although often overlooked in clinical settings, accumulation of persistent organic pollutants (POPs) in visceral adipose tissue (VAT) is thought to be a relevant risk factor for metabolic syndrome (MetS).

METHODS

One hundred and seventeen patients undergoing non-oncological surgery were randomly recruited and classified as MetS + if presented 3 out of the 5 MetS components: waist circumference (WC), systolic and diastolic blood pressure (SBP and DBP, respectively), serum glucose, insulin, triglycerides (TG) and high-density lipoprotein (HDL) cholesterol levels, according International Diabetes Federation (IDF) criteria. Seventeen organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were measured in adipose tissue samples. Linear, logistic and weighted quantile sum (WQS) regression models, adjusted for age and sex, were performed.

RESULTS

One third of the participants were males (36.8%) with a median age of 44 years, showing clinical evidences of MetS (35.0%). Adjusted linear regression models showed that WC correlated positively with all OCP concentrations. Higher fasting serum glucose levels were related to higher HCB and γ-HCH concentrations. The remaining OCPs and PCBs were not associated with this MetS component. HCB was inversely associated with HDL cholesterol levels, while PCB-180 was positively associated. HCB and γ-HCH concentrations were also positively correlated with DBP and SBP levels. PCB-138 was also positively associated with SBP. Adjusted logistic models revealed that exposure to HCB and γ-HCH were associated with increased odds of MetS [ORs (95%CI) 1.53 (1.22-1.92) and 1.39 (1.10-1.76) respectively; p < 0.01]. No associations were observed for the remaining POPs. WQS models showed a positive and significant mixture effect of POPs on the odds of MetS (exp [beta] = 2.34; p < 0.001), with γ-HCH (52.9%), o,p'-DDT (26.9%) and HCB (19.7%) driving the association.

CONCLUSIONS

Our findings support that POPs accumulated in VAT, specifically HCB and (gamma)-HCH, are associated with both isolated components and clinically diagnosed SMT.

PCB cause global DNA hypomethylation of human peripheral blood monocytes in vitro

We have recently reported significant associations between exposure to polychlorinated biphenyls (PCB) and alterations on genome-wide methylation of leukocyte DNA of healthy volunteers and provided evidence in support of an etiological link between the observed CpG methylation variations and chronic lymphocytic leukemia. The present study aimed to elucidate the effects of PCB in human lymphocytes' methylome in vitro. Therefore, U937 cells and human peripheral blood monocytes (PBMC) were exposed in vitro to the dioxin-like PCB-118, the non-dioxin-like PCB-153, and hexachlorobenzene (HCB) and thorough cytotoxicity, genotoxicity and global CpG methylation analyses were performed. All compounds currently tested did not show any consistent significant genotoxicity at all exposure periods and concentrations used. On the contrary, extensive dose-dependent hypomethylation was observed, even at low concentrations, in stimulated PBMC treated with PCB-118 and PCB-153 as well as a small but statistically significant hypomethylation in HCB-treated stimulated cells.

Sustained bloodstream release of persistent organic pollutants induced by extensive weight loss after bariatric surgery: Implications for women of childbearing age

BACKGROUND

Lipophilic persistent organic pollutants (POPs) are stored in adipose tissues and released in case of weight loss.

OBJECTIVES

To analyze the kinetics and characteristics of this release during drastic weight loss after bariatric surgery and compare the results in case of women of childbearing age (WCBA) with critical blood concentration thresholds.

METHODS

100 morbidly obese patients (73 women including 53 of childbearing age and 27 men) were screened before and 3, 6 and 12 months after bariatric surgery for serum concentrations of 67 congeners or metabolites of banned or not yet banned organohalogenated persistent pollutants, including highly lipophilic polychlorobiphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), and less lipophilic perfluorinated alkylated substances (PFASs).

RESULTS

Circulating levels of all chemicals, except PFASs, increased progressively after surgery, reaching after one year an increase between 30 and 139% compared to initial pre-surgical levels; median levels increased for PCB153 from 36.8 to 86.4 ng/g lw (+130%), for dichlorodiphenyldichloroethylene (p,p'-DDE) from 59.8 to 136.1 ng/g lw (+120%), and for hexachlorobenzene (HCB) from 9.8 to 20.3 ng/g lw (+110%). Weight loss averaging 30% of initial body weight at 12 months in both sexes (mean: 40.0 kg for men, 36.1 kg for women), was the main parameter related to the concentration increases (3.1 to 3.6% per kilogram weight loss). They were not dependent on initial BMI, presence of metabolic syndrome or type of surgical procedure but influenced by gender and biochemical properties such as degree of chlorination for PCBs and/or lipophilicity since PFASs did not increase at all. ∑PCB₆ in blood after one year exceeded the critical concentration threshold for 24.5% women of childbearing age (13/53) versus 3.6% (2/53) before surgery.

DISCUSSION

Massive weight loss within the first year following bariatric surgery is associated with a sustained increase of circulating lipophilic POPs. Short- and long-term consequences should be considered, mostly for childbearing age obese women, because of potential health risks for the future fetus and breastfeeding infant.

Association of endocrine active environmental compounds with body mass index and weight loss following bariatric surgery

INTRODUCTION

The objective of this study was to study associations of a wide range of halogenated biphenyls, dibenzo-p-dioxins, dibenzofurans and diphenylethers with body mass index (BMI) and evaluate changes in their concentration following bariatric surgery.

METHODS

Subcutaneous fat, visceral fat and liver tissue samples were collected from 106 patients undergoing Roux-en-Y gastric bypass surgery for weight loss or patients who were undergoing abdominal surgery for nonbariatric reasons. We measured concentrations of an extensive panel of chlorinated and brominated biphenyls, dioxins, and furans, and brominated diphenylethers in the samples. We conducted linear regression to examine associations with BMI, adjusting for age and gender. Changes in concentration for indicator chemicals were evaluated in samples collected following bariatric surgery in a small subpopulation.

RESULTS

After adjustments for age and gender and correction for multiple testing, seven ortho-chlorinated biphenyls, one nonortho-chlorinated biphenyl, four PCDD/Fs and one ortho-brominated biphenyl were associated with BMI. The strongest associations between BMI and lipid-adjusted concentrations were seen with PCB-105 in subcutaneous fat (beta = 16.838 P-val = 1.45E-06) PCB-126 in visceral fat (beta = 15.067 P-val = 7.72E-06) and PCB-118 (beta = 14.101 P-val = 2.66E-05) in liver. The concentrations of sum PCBs, chlorinated toxic equivalent quantity (TEQ's) and brominated compounds increased significantly with weight loss in subcutaneous fat in a group of ten individuals resampled up to five years after bariatric surgery and substantial weight loss.

CONCLUSION

We show that selected polychlorinated biphenyls PCBs and structurally related polychlorinated dibenzo-p-dioxins dibenzofurans (PCDD/Fs) were associated with BMI. Concentrations of these lipophilic compounds in subcutaneous fat increased following bariatric surgery.

Constitutive androstane receptor mediates PCB-induced disruption of retinoid homeostasis

Environmental exposure to polychlorinated biphenyls (PCBs) is associated with an increased risk of incidence of metabolic disease, however the molecular mechanisms underlying this phenomenon are not fully understood. Our study provides new insights into molecular interactions between PCBs and retinoids (vitamin A and its metabolites) by defining a role for constitutive androstane receptor (CAR) in the disruption of retinoid homeostasis by non-coplanar 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153). Administration of four weekly 50 mg/kg doses of PCB153 to C57BL/6 male mice resulted in a significant decline in the tissue concentrations of retinyl esters, retinol and all-trans-retinoic acid (atRA), while no decline in hepatic and adipose tissue retinoid levels were detected in Car-null littermates. Our data imply that disrupted retinoid homeostasis occurs as a consequence of PCB153-induced activation of CAR, and raise the possibility that CAR signaling can affect atRA homeostasis in vivo. A strong correlation between the changes in retinoid metabolism and extensive upregulation of hepatic CAR-driven Cyp2b10 expression implicates this CYP isoform as contributing to retinoid homeostasis disruption via atRA oxidation during PCB153 exposure. In response to PCB153-induced CAR activation and disruption of retinoid homeostasis, expression of hepatic Pepck, Cd36 and adipose tissue Pparγ, Cd36, Adipoq, and Rbp4 were altered; however, this was reversed by administration of exogenous dietary retinoids (300 IU daily for 4 weeks). Our study establishes that PCB153 exposure enables a significant disruption of retinoid homeostasis in a CAR-dependent manner. We propose that this contributes to the obesogenic properties of PCB153 and may contribute to the predisposition to the metabolic disease.

Decreased plasma levels of perfluoroalkylated substances one year after bariatric surgery

Per- and polyfluoroalkylated substances (PFASs) are classified as persistent organic pollutants (POPs), and known to be protein bound. The aim of the present study was to determine the levels of 17 different PFASs before and one year after bariatric surgery, and to assess whether weight loss and changed serum protein concentrations could be influencing factors. Plasma samples from 63 patients were analyzed for nine perfluoroalkyl carboxylic acids (PFCAs), three perfluoroalkane sulfonic acids (PFSAs), and five perfluoroalkyl sulfonamide based substances (PASF) before and after surgery. Protein determination was performed in the corresponding serum samples. Mean weight loss one year after surgery was 32.1 kg. The plasma levels of all PFASs decreased with 4-34% compared to preoperative values, and included perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), and perfluorobutane sulfonate (PFBS), which have been identified with increasing levels in the general population during recent years. Serum protein concentrations also decreased with 7-8%. Although protein levels were positively correlated with PFOA, PFBS, PFHxS and PFOS, regression analysis revealed that neither weight loss nor reductions in concentrations of serum protein could explain the decreased PFAS levels. The type of surgical procedure did not influence the changes of PFAS levels between the two sample points. A reduced food intake and alterations in absorptions of nutrients after bariatric surgery may have influenced the observed decreasing plasma levels of PFASs.

Interventions to Address Environmental Metabolism-Disrupting Chemicals: Changing the Narrative to Empower Action to Restore Metabolic Health

Metabolic disease rates have increased dramatically over the last four decades. Classic understanding of metabolic physiology has attributed these global trends to decreased physical activity and caloric excess; however, these traditional risk factors insufficiently explain the magnitude and rapidity of metabolic health deterioration. Recently, the novel contribution of environmental metabolism-disrupting chemicals (MDCs) to various metabolic diseases (including obesity, diabetes, and non-alcoholic fatty liver disease) is becoming recognized. As this burgeoning body of evidence has matured, various organic and inorganic pollutants of human and natural origin have emerged as metabolic disease risk factors based on population-level and experimental data. Recognition of these heretofore underappreciated metabolic stressors now mandates that efforts to mitigate the devastating consequences of metabolic disease include dedicated efforts to address environmental drivers of disease risk; however, there have not been adequate recommendations to reduce exposures or to mitigate the effects of exposures on disease outcomes. To address this knowledge gap and advance the clinical translation of MDC science, herein discussed are behaviors that increase exposures to MDCs, interventional studies to reduce those exposures, and small-scale clinical trials to reduce the body burden of MDCs. Also, we discuss evidence from cell-based and animal studies that provide insights into MDC mechanisms of action, the influence of modifiable dietary factors on MDC toxicity, and factors that modulate MDC transplacental carriage as well as their impact on metabolic homeostasis. A particular emphasis of this discussion is on critical developmental windows during which short-term MDC exposure can elicit long-term disruptions in metabolic health with potential inter- and transgenerational effects. While data gaps remain and further studies are needed, the current state of evidence regarding interventions to address MDC exposures illuminates approaches to address environmental drivers of metabolic disease risk. It is now incumbent on clinicians and public health agencies to incorporate this knowledge into comprehensive strategies to address the metabolic disease pandemic.

One-year impact of bariatric surgery on serum anti-Mullerian-hormone levels in severely obese women

INTRODUCTION

Although bariatric surgery seems to increase spontaneous fertility by improving ovulatory function in young women, its impact on ovarian reserve remains largely unknown.

OBJECTIVE

To evaluate changes in serum anti-Mullerian hormone (AMH) levels in reproductive-age severely obese women after bariatric surgery (BS).

METHODS

AMH levels were measured retrospectively in 39 women (mean age 34.6 ± 1.1 years, range 18-45) that underwent a sleeve gastrectomy or Roux-en-Y gastric bypass (RYGB) at baseline, and 6 and 12 months after BS. Metabolic and micronutrient status, including fasting plasma insulin and glucose, HOMA-IR, leptin, adiponectin, calcium, albumin, transthyretin, ferritin, vitamins (B9, B12, B1, A, E, D), zinc, and selenium, were assessed in all patients before and 1 year after BS.

RESULTS

Of the patients, 79% had class-3 obesity. At 6 and 12 months, mean total weight losses (TWL) were 26 and 30%; mean excess weight losses (EWL) were 61.7 and 70.2%. Compared to baseline, AMH levels significantly decreased by 18% at 6 months, and 32% at 12 months post-operatively (p = 0.010 and p = 0.001, respectively). There was no correlation between AMH variation and changes in metabolic parameters or micronutrient levels. Remarkably, changes in AMH levels did not differ between sleeve and RYGB patients and were not correlated with EWL.

CONCLUSION

This pilot study shows a drastic reduction in AMH levels at 1 year after BS in reproductive-age severely obese women, which was not related to weight loss: this suggests a negative impact of BS on ovarian reserve, at least in the short term.

Increased levels of persistent organic pollutants in serum one year after a great weight loss in humans: Are the levels exceeding health based guideline values?

BACKGROUND

With the growing prevalence of obesity, an increased number of bariatric surgeries are being performed. Lipophilic persistent organic pollutants (POPs) are stored in adipose tissue, and an increased release of lipophilic POPs into the blood circulation may occur following rapid weight loss such as after bariatric surgery.

OBJECTIVES

To evaluate and compare POP levels in serum before and after bariatric surgery, and to assess if the POP levels exceeded health based guideline values, with particular focus on women of childbearing age (WCBA).

METHODS

Serum samples from 63 patients before and one year after bariatric surgery were analysed for organochlorine pesticides (OCPs); polychlorinated biphenyls (PCBs); and brominated flame retardants (BFRs).

RESULTS

Mean weight loss one year after surgery was 32.1kg. The levels of all the analysed POPs in serum increased during the study period. Median levels of dichlorodiphenyldichloroethylene (p,p'-DDE), hexachlorobenzen (HCB) and PCB-153 increased from 90.2ng/g lipid weight (lw) to 158.5ng/glw, from 21.1ng/glw to 36.4ng/glw and from 48.7ng/glw to 71.5ng/glw, respectively. The highest percentage increase was observed for PCB -138, with 83.1%. BFRs were detected in low sample numbers and at low levels. Guideline values for ΣPCB₆ in serum were exceeded for 5% of the participants.

CONCLUSIONS

Weight loss after bariatric surgery resulted in increases of POPs levels in serum between 46.7%-83.1%. Guideline values for ΣPCB₆ in serum were exceeded for 5% of the participants. For WCBA, the possible transfer of comparable levels to infants warrants further attention.

Blood Concentrations of Persistent Organic Pollutants and Unhealthy Metabolic Phenotypes in Normal-Weight, Overweight, and Obese Individuals

Factors underlying metabolic phenotypes, such as the metabolically healthy but obese phenotype, remain unclear. Differences in metabolic phenotypes-particularly, among individuals with a similar body mass index-could be related to concentrations of persistent organic pollutants (POPs). To our knowledge, no studies have analyzed POPs and metabolic phenotypes in normal-weight persons. We investigated the relationships between serum concentrations of POPs and metabolic phenotypes in 860 normal-weight, overweight, and obese participants in the 2002 Catalan Health Interview Survey (Spain). POP concentrations were significantly higher in metabolically unhealthy than in metabolically healthy individuals. In models adjusting for body mass index and other confounders, hexachlorobenzene, β-hexachlorocyclohexane, and polychlorinated biphenyls were associated with the unhealthy metabolic phenotype and metabolic syndrome. Among normal-weight individuals, the adjusted prevalence ratio of having an unhealthy phenotype for the upper category of the sum of orders of the 6 mentioned POPs (all individually associated with metabolic phenotypes) was 4.1 (95% confidence interval: 1.7, 10.0). Among overweight and obese individuals, the corresponding prevalence ratio for the sum of polychlorinated biphenyls was 1.4 (95% confidence interval: 1.0, 1.8). Our results supported the hypothesis that POP concentrations are associated with unhealthy metabolic phenotypes, not only in obese and overweight individuals but also (and probably more strongly) in normal-weight individuals.

Serum Polychlorinated Biphenyls Increase and Oxidative Stress Decreases with a Protein-Pacing Caloric Restriction Diet in Obese Men and Women

The purposes were to compare the effects of a: (1) 12-week P-CR weight loss (WL) diet (Phase 1) between obese men and women and; (2) 52-week modified P-CR (mP-CR) vs. heart healthy (HH) weight maintenance (WM) diet (Phase 2) on serum PCBs and oxidative stress biomarkers (thiobarbituric acid reactive substances, TBARS; total antioxidant capacity, TAC) in 40 obese participants (men, n = 21; women, n = 19). Participants received dietary counseling and monitoring of compliance. PCBs, TBARS, and TAC were assessed at weeks -1 (CON), 12 (WL), and 64 (WM). Following WL (Week 12), concomitant with reductions in TBARS (0.24 ± 0.15 vs. 0.18 ± 0.11 µM; p < 0.01), PCB serum concentrations (86.7 ± 45.6 vs. 115.6 ± 65.9 ng/g lipid; p < 0.01) and TAC (18.9 ± 2.6 vs. 19.9 ± 2.3 nmol/mL; p < 0.02) were increased similarly in men and women. At the end of WM (Week 64), a significant effect of time × group interaction was observed for % change in PCB 170 and 187; whereby mP-CR values were higher compared to HH (PCB170: 19.31% ± 26.48% vs. -6.61% ± 28.88%, p = 0.02; PCB187: -3.04% ± 17.78% vs. -21.4% ± 27.31%, p = 0.04). PCB changes were positively correlated with TBARS levels (r > 0.42, p < 0.05) and negatively correlated with body weight, fat mass, and abdominal fat (r < -0.46, p < 0.02). Our results support mobilization of stored PCBs as well as enhanced redox status following a 12-week P-CR WL diet. Additionally, a 52-week mP-CR WM diet demonstrated an advantage in preventing weight gain relapse accompanied by an increase in circulating PCBs compared to a traditional HH diet.

Increased blood levels of persistent organic pollutants (POP) in obese individuals after weight loss-A review

Lipophilic persistent organic pollutants (POP) are stored in adipose tissue. Following rapid weight loss such as when induced by bariatric surgery, an increased release of potential harmful lipophilic compounds into the blood circulation may occur. Weight reduction is recommended for overweight and obese individuals in order to decrease risk of weight-related health problems. However, in cases of significant weight reduction POP become mobilized chemicals and consequently may adversely affect health, including endocrine disruption. The objective of the present investigation was to estimate quantitatively the level of mobilization of POP following weight loss over time. According to literature search criteria, 17 studies were identified with 2061 participants. Data from 5 of the studies with 270 participants were used to assess the change in blood levels of POP in percent per kilogram weight loss. Weight loss in the included studies varied from 4.4 to 64.8 kg. In all studies, the majority of POP concentrations in blood were found to rise following weight reduction. Blood concentrations following weight reduction were elevated by 2-4% per kilogram weight loss for most POP examined. The increased POP levels were still elevated 12 mo after intervention. Most research in this field, including animal studies, is carried out on a single compound or group of selected compounds, not taking the "cocktail effect" into consideration. This does not reflect the true range of POP to which humans are actually exposed. Few chronic investigations have been published and, in particular, few studies were available that compared the increase in POP concentrations with clinical consequences as individuals lost weight. These limitations call for caution in interpreting results. The benefits of losing weight still far outweigh the potential adverse health risks. However, further studies are recommended to determine the clinical significance of increased blood levels of POPs following rapid and excessive weight loss, particularly for women attending weight reduction treatment before pregnancy.