Endocrine disruptors in the etiology of type 2 diabetes mellitus

Association of perfluoroalkyl substances exposure with cardiometabolic traits in an island population of the eastern Adriatic coast of Croatia

BACKGROUND

Exposure to perfluoroalkyl substances (PFAS), ubiquitous environmental contaminants, may be related to cardiometabolic diseases in adults. Studies in European populations to examine the association of PFAS exposure and comprehensive cardiometabolic traits and metabolic syndrome (MetS) are limited.

METHODS

In this pilot cross-sectional study of a well-characterized adult population of the island of Hvar, situated off the eastern Adriatic coast of Croatia, we measured PFAS concentrations in plasma samples collected during 2007-2008 and examined their cross-sectional associations with cardiometabolic traits and MetS after adjustment of covariates (n = 122). PFAS investigated in this study included perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA).

RESULTS

The geometric mean (range) was 8.91 (2.36, 33.67) ng/mL for PFOS, 2.87 (1.03, 8.02) ng/mL for PFOA, 0.77 (0.25, 2.40) ng/mL for PFHxS, and 1.29 (0.48, 3.46) ng/mL for PFNA, with frequency of detection at 100%, 100%, 95.9%, and 100%, respectively. PFOS, PFOA, and PFNA concentrations were positively associated with the risk of MetS as defined by the Adult Treatment Panel III (ATP III) criteria, with estimated odds ratios and 95% confidence intervals at 1.89 (0.93, 3.86), 2.19 (0.88, 5.44), and 2.95 (1.12, 7.80), respectively, with only PFNA reaching statistical significance. PFNA concentrations were associated with increased risk of overweight or obesity.

CONCLUSIONS

Background exposure to PFOS, PFOA, and PFNA was marginally associated with increased risk of MetS in this small study, and these results should be confirmed with a larger sample size and longitudinal follow-up.

Estrogen withdrawal and replacement differentially target liver and adipose tissues in female mice fed a high-fat high-sucrose diet: impact of a chronic exposure to a low-dose pollutant mixture☆

Postmenopausal women may be at particular risk when exposed to chemicals especially endocrine disruptors because of hormonal deficit. To get more insight, ovariectomized C57Bl6/J mice fed a high-fat high-sucrose diet were chronically exposed from 5 to 20 weeks of age to a low-dose mixture of chemicals with one dioxin, one polychlorobiphenyl, one phthalate and bisphenol A. Part of the mice received as well E2 implants to explore the potential estrogenic dependency of the metabolic alterations. With this model, estrogen loss resulted in glucose but not lipid metabolism impairment, and E2 replacement normalized the enhanced body and fat pad weight, and the glucose intolerance and insulin resistance linked to ovariectomy. It also altered cholesterol metabolism in the liver concurrently with enhanced estrogen receptor Esr1 mRNA level. In addition, fat depots responded differently to estrogen withdrawal (e.g., selective mRNA enhancement of adipogenesis markers in subcutaneous and of inflammation in visceral fat pads) and replacement challenges. Importantly, the pollutant mixture impacted lipid deposition and mRNA expression of several genes related to lipid metabolism but not Esr1 in the liver. Adiponectin levels were altered as well. In addition, the mRNA abundance of the various estrogen receptors was regionally impacted in fat tissues. Besides, xenobiotic processing genes did not change in response to the pollutant mixture in the liver. The present findings bring new light on estrogen-dependent metabolic alterations with regards to situations of loss of estrogens as observed after menopause.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the differentiation of embryonic stem cells towards pancreatic lineage and pancreatic beta cell function

Animal and epidemiological studies demonstrated association of persistent exposure of TCDD, an endocrine disrupting chemical, to susceptibility of type 2 diabetes (T2D). High doses of TCDD were commonly employed in experimental animals to illustrate its diabetogenic effects. Data linking the epigenetic effects of low doses of TCDD on embryonic cells to T2D susceptibility risks is very limited. To address whether low dose exposure to TCDD would affect pancreatic development, hESCs pretreated with TCDD at concentrations similar to human exposure were differentiated towards pancreatic lineage cells, and their global DNA methylation patterns were determined. Our results showed that TCDD-treated hESCs had impaired pancreatic lineage differentiation potentials and altered global DNA methylation patterns. Four of the hypermethylated genes (PRKAG1, CAPN10, HNF-1B and MAFA) were validated by DNA bisulfite sequencing. PRKAG1, a regulator in the AMPK signaling pathway critical for insulin secretion, was selected for further functional study in the rat insulinoma cell line, INS-1E cells. TCDD treatment induced PRKAG1 hypermethylation in hESCs, and the hypermethylation was maintained after pancreatic progenitor cells differentiation. Transient Prkag1 knockdown in the INS-1E cells elevated glucose stimulated insulin secretions (GSIS), possibly through mTOR signaling pathway. The current study suggested that early embryonic exposure to TCDD might alter pancreatogenesis, increasing the risk of T2D.

Upregulation of GABA receptor promotes long-term potentiation and depotentiation in the hippocampal CA1 region of mice with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a long-term metabolic disorder characterized by high blood sugar levels, insulin resistance and a relative lack of insulin. A previous study has reported that an association exists between γ-aminobutyric acid (GABA) and the hippocampus. The current study therefore aimed to assess the effect of the GABA receptor (GABA-R) on the long-term potentiation (LTP) and depotentiation of the hippocampal CA1 region in mice with T2DM. Mice were divided into four groups: A normal group consisting of healthy mice and a GABA-R, negative control and blank group all comprising T2DM mice. The weight and blood glucose level of all mice were measured and GABA-R mRNA and protein expression were detected. A hydroxyl free radical (OH-) kit was used to determine the hippocampal OH-content. Using an electrophysiological experiment, the population spike (PS) slope was observed every 5 min. The results revealed that as GABA-R levels increased, the weight, blood glucose level and OH⁻ content of the T2DM mice significantly decreased, and the neuron microstructures in the mice hippocampal tissue improved. The PS slope also significantly increased and the level of depotentiation improved. The results of the current study support the theory that the upregulation of GABA-R protects the neuronal ultrastructure and promotes LTP and depotentiation in the hippocampal CA1 region by inhibiting the accumulation of OH⁻ in T2DM mice.

Increasing evidence of pathogenic role of the Mediator (MED) complex in the development of cardiovascular diseases

Cardiovascular diseases (CVDs) are the first cause of death in the World. Mediator (MED) is an evolutionarily conserved protein complex, which mediates distinct protein-protein interactions. Pathogenic events in MED subunit have been associated with human diseases. Novel increasing evidence showed that missense mutations in MED13L gene are associated with transposition of great arteries while MED12, MED13, MED15, and MED30, have been correlated with heart development. Moreover, MED23 and MED25 have been associated with heart malformations in humans. Relevantly, MED1, MED13, MED14, MED15, MED23, MED25, and CDK8, were found modify glucose and/or lipid metabolism. Indeed, MED1, MED15, MED25, and CDK8 interact in the PPAR- and SREBP-mediated signaling pathways. MED1, MED14 and MED23 are involved in adipocyte differentiation, whereas MED23 mediates smooth muscle cell differentiation. MED12, MED19, MED23, and MED30 regulate endothelial differentiation by alternative splicing mechanism. Thus, MEDs have a central role in early pathogenic events involved in CVDs representing novel targets for clinical prevention and therapeutic approaches.

The effect of bisphenol a exposure onto endothelial and decidualized stromal cells on regulation of the invasion ability of trophoblastic spheroids in in vitro co-culture model

Bisphenol A (BPA) is a kind of environmental endocrine disruptors (EEDs) that interfere embryo implantation. Trophoblast invasion plays a crucial role during embryo implantation. In this study, the effects of BPA on invasion ability of human trophoblastic Jeg-3 spheroids and regulation of endothelial and stromal cells on trophoblastic spheroids invasion, and its possible mechanism were investigated. The results showed that BPA at 10 and 100 μM can inhibit the attachment of Jeg-3 spheroid onto Ishikawa cells. BPA at 1-100 μM also activate ERE-Luc reporter expression in the transfected cells, which was through the ERα, but not ERβ or GPR30 binding. Endothelial receptivity ability was harmed by BPA treatment since receptivity markers of LIF, EGF, MUC1 and integrin αVβ3 were decreased after BPA treatment. The invasion ability of trophoblastic spheroids generated from Jeg-3 cell line was inhibited by BPA and this effect was mediated through canonical ERs pathway and MMP2/MMP9 down-regulation and TIMP1/PAI-1 up-regulation. Besides, BPA treated decidualized stromal cells suppressed Jeg-3 spheroid outgrowth and invasion in co-culture assay. Our study would give a better understanding on the possible mechanism of BPA effect on human embryo implantation process.

Recent advances in the detection of 17β-estradiol in food matrices: A review

Pollution of endocrine disrupting chemicals has become a global issue. As one of the hormonally active compounds, 17β-estradiol produces the strongest estrogenic effect when it enters the organism exogenously including food intakes, bringing potential harmfulness such as malfunction of the endocrine system. Therefore, in order to assure food safety and avoid potential risks of 17β-estradiol to humans, it is of great significance to develop rapid, sensitive and selective approaches for the detection of 17β-estradiol in food matrices. In this review, the harmfulness and main sources of 17β-estradiol are firstly introduced, followed by the description of the principles and applications of different approaches for 17β-estradiol detection including high performance liquid chromatography, electrochemistry, Raman spectroscopy, fluorescence and colorimetry. Particularly, applications in detecting 17β-estradiol in food matrices over the years of 2010-2018 are discussed. Finally, advantages and limitations of these detection methods are highlighted and perspectives on future developments in the detection methods for 17β-estradiol are also proposed. Although many detection approaches can achieve trace or ultratrace detection of 17β-estradiol, further studies should be focused on the development of in-situ and real-time methods to monitor and evaluate 17β-estradiol for food safety.

Developmental exposure to a very low dose of bisphenol A induces persistent islet insulin hypersecretion in Fischer 344 rat offspring

BACKGROUND

In children with obesity, accentuated insulin secretion has been coupled with development of type 2 diabetes mellitus (T2DM). Bisphenol A (BPA) is a chemical with endocrine- and metabolism-disrupting properties which can be measured in a majority of the population. Exposure to BPA has been associated with the development of metabolic diseases including T2DM.

OBJECTIVE

The aim of this study was to investigate if exposure early in life to an environmentally relevant low dose of BPA causes insulin hypersecretion in rat offspring.

METHODS

Pregnant Fischer 344 rats were exposed to 0.5 (BPA0.5) or 50 (BPA50) µg BPA/kg BW/day via drinking water from gestational day 3.5 until postnatal day 22. Pancreata from dams and 5- and 52-week-old offspring were procured and islets were isolated by collagenase digestion. Glucose-stimulated insulin secretion and insulin content in the islets were determined by ELISA.

RESULTS

Basal (5.5 mM glucose) islet insulin secretion was not affected by BPA exposure. However, stimulated (11 mM glucose) insulin secretion was enhanced by about 50% in islets isolated from BPA0.5-exposed 5- and 52-week-old female and male offspring and by 80% in islets from dams, compared with control. In contrast, the higher dose, BPA50, reduced stimulated insulin secretion by 40% in both 5- and 52-week-old female and male offspring and dams, compared with control.

CONCLUSION

A BPA intake 8 times lower than the European Food Safety Authority's (EFSA's) current tolerable daily intake (TDI) of 4 µg/kg BW/day of BPA delivered via drinking water during gestation and early development causes islet insulin hypersecretion in rat offspring up to one year after exposure. The effects of BPA exposure on the endocrine pancreas may promote the development of metabolic disease including T2DM.

Perfluoroalkyl substances, metabolomic profiling, and alterations in glucose homeostasis among overweight and obese Hispanic children: A proof-of-concept analysis

OBJECTIVE

To examine the prospective associations between exposure to perfluoroalkyl substances (PFASs) and longitudinal measurements of glucose metabolism in high-risk overweight and obese Hispanic children.

METHODS

Forty overweight and obese Hispanic children (8-14 years) from urban Los Angeles underwent clinical measures and 2-hour oral glucose tolerance tests (OGTT) at baseline and a follow-up visit (range: 1-3 years after enrollment). Baseline plasma perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonic acid (PFHxS), and the plasma metabolome were measured by liquid-chromatography with high-resolution mass spectrometry. Multiple linear regression models were used to assess the association between baseline PFASs and changes in glucose homeostasis over follow-up. A metabolome-wide association study coupled with pathway enrichment analysis was performed to evaluate metabolic dysregulation associated with plasma PFASs concentrations. We performed a structural integrated analysis aiming to characterize the joint impact of all factors and to identify latent clusters of children with alterations in glucose homeostasis, based on their exposure and metabolomics profile.

RESULTS

Each ln (ng/ml) increase in PFOA and PFHxS concentrations was associated with a 30.6 mg/dL (95% CI: 8.8-52.4) and 10.2 mg/dL (95% CI: 2.7-17.7) increase in 2-hour glucose levels, respectively. A ln (ng/ml) increase in PFHxS concentrations was also associated with 17.8 mg/dL increase in the glucose area under the curve (95% CI: 1.5-34.1). Pathway enrichment analysis showed significant alterations of lipids (e.g., glycosphingolipids, linoleic acid, and de novo lipogenesis), and amino acids (e.g., aspartate and asparagine, tyrosine, arginine and proline) in association to PFASs exposure. The integrated analysis identified a cluster of children with increased 2-h glucose levels over follow up, characterized by increased PFAS levels and altered metabolite patterns.

CONCLUSIONS

This proof-of-concept analysis shows that higher PFAS exposure was associated with dysregulation of several lipid and amino acid pathways and longitudinal alterations in glucose homeostasis in Hispanic youth. Larger studies are needed to confirm these findings and fully elucidate the underlying biological mechanisms.

Chronic exposure to a pollutant mixture at low doses led to tissue-specific metabolic alterations in male mice fed standard and high-fat high-sucrose diet

Excessive consumption of industrialized food and beverages is a major etiologic factor in the epidemics of obesity and associated metabolic diseases because these products are rich in fat and sugar. In addition, they contain food contact materials and environmental pollutants identified as metabolism disrupting chemicals. To evaluate the metabolic impact of these dietary threats (individually or combined), we used a male mouse model of chronic exposure to a mixture of low-dose archetypal food-contaminating chemicals that was added in standard or high-fat, high-sucrose (HFHS) diet. Specifically, the mixture contained bisphenol A, diethylhexylphthalate, 2,3,7,8-tetrachlorodibenzo-p-dioxine and polychlorinated biphenyl 153. Exposure lasted from 5 to 20 weeks of age. Metabolic exploration was conducted setting the basis of candidate gene expression mRNA analyses in liver, jejunum and adipose tissue depots from 20 week-old mice. Strong metabolic deleterious effects of the HFHS diet were demonstrated in line with obesity-associated metabolic features and insulin resistance. Pollutant exposure resulted in significant changes on plasma triglyceride levels and on the expression levels of genes mainly encoding xenobiotic processing in jejunum; estrogen receptors, regulators of lipoprotein lipase and inflammatory markers in jejunum and adipose tissues as well as adipogenesis markers. Importantly, the impact of pollutants was principally evidenced under standard diet. In addition, depending on nutritional conditions and on the metabolic tissue considered, the impact of pollutants could mimic or oppose the HFHS effects. Collectively, the present study extends the cocktail effect concept of a low-dosed pollutant mixture and originally points to tissue-specificity responsiveness especially in jejunum and adipose tissues.

Effects of perinatal exposure to BPA, BPF and BPAF on liver function in male mouse offspring involving in oxidative damage and metabolic disorder

Bisphenols (BPs) are common environmental pollutants that are ubiquitous in the natural environment and can affect human health. In this study, we explored the effects of perinatal exposure to BPA, BPF and BPAF on liver function involving in oxidative damage and metabolic disorders in male mouse offspring. We found that BPA exposure impairs the antioxidant defense system, increases lipid peroxidation, and causes oxidative damage in the liver. Furthermore, the levels of 13 metabolites were significantly altered following BPA exposure. We found that BPF exposure significantly increased the expression and activity of CAT, suggesting disturbances in the antioxidant defense system. Moreover, BPF exposure led to metabolic disorders in the liver due to changes in the levels of 8 key metabolites. Exposure to BPAF caused no negative effects on oxidative damage, but altered the levels of β-glucose and glycogen. In summary, perinatal exposure to BPA, BPF and BPAF differentially influence oxidative damage and metabolic disorders in the livers of male mouse offspring. The impact of early life exposure to BPs now warrants future investigations.

Role of cadmium and arsenic as endocrine disruptors in the metabolism of carbohydrates: Inserting the association into perspectives

Endocrine disrupting chemicals (EDCs) have widespread environmental distribution originated from both natural and anthropogenic sources. From the last few decades, their contamination has been raised dramatically owing to continuous discharge in sewage and untreated industrial effluents. They have rapidly gained a considerable attention due to their critical role in the development of multiple endocrine-related disorders notably diabetes mellitus (DM). Cadmium and arsenic, among the most hazardous EDCs, are not only widely spread in our environment, but they are also found to be associated with wide range of health hazards. After entering into the human body, they are preferably accumulated in the liver, kidney and pancreas where they exhibit deleterious effects on carbohydrate metabolism pathways notably glycolysis, glucogenesis and gluconeogenesis through the modification and impairment of relevant key enzymes activity. Impairment of hepatic glucose homeostasis plays a crucial role in the pathogenesis of DM. Along with compromised function of pancreas and muscles, diminished liver and kidney functions also contribute considerably to increase the blood glucose level. These metals have potential to bring conformational changes in these enzymes and make them inactive. Additionally, these metals also disturb the hormonal balance, such as insulin, glucocorticoids and catecholamines; by damaging pancreas and adrenal gland, respectively. Moreover, these metals also enhance the production of reactive oxygen species and depress the anti-oxidative defense mechanism with subsequent disruption of multiple organs. In this article, we have briefly highlighted the impact of arsenic and cadmium on the metabolism of carbohydrates and the enzymes that are involved in carbohydrate metabolism and glucose homeostasis.

Perfluoroalkyl substances and risk of type II diabetes: A prospective nested case-control study

BACKGROUND

Perfluoroalkyl substances (PFAS) have drawn much attention due to bioaccumulation potential and their current omnipresence in human blood. We assessed whether plasma PFAS, suspected to induce endocrine-disrupting effects, were prospectively associated with clinical type 2 diabetes (T2D) risk.

METHODS

We established a nested case-control study within the Swedish prospective population-based Västerbotten Intervention Programme cohort. Several PFAS were measured in plasma from a subset of 124 case-control pairs at baseline (during 1990-2003) and at 10-year follow-up. T2D cases were matched (1:1) according to gender, age and sample date with participants without T2D (controls). Conditional logistic regressions were used to prospectively assess risk of T2D by baseline PFAS plasma concentrations. Associations between long-term PFAS plasma levels (mean of baseline and follow-up) and insulin resistance (HOMA2-IR) and beta-cell function (HOMA2-B%) at follow-up were prospectively explored among 178 and 181 controls, respectively, by multivariable linear regressions.

RESULTS

After adjusting for gender, age, sample year, diet and body mass index, the odds ratio of T2D for the sum of PFAS (Σ z-score PFAS) was 0.52 (95% confidence interval, CI: 0.20, 1.36), comparing third with first tertile; and 0.92 (95% CI: 0.84, 1.00) per one standard deviation increment of sum of log-transformed PFAS. Among the controls, the adjusted β of HOMA2-IR and HOMA-B% for the sum of PFAS were -0.26 (95% CI: -0.52, -0.01) and -9.61 (95% CI: -22.60, 3.39) respectively comparing third with first tertile.

CONCLUSIONS

This prospective nested case-control study yielded overall inverse associations between individual PFAS and risk of T2D, although mostly non-significant. Among participants without T2D, long-term PFAS exposure was prospectively associated with lower insulin resistance.

Endocrine disruption as an adverse effect of non-endocrine targeting pharmaceuticals

Endocrine disruptors have gained widespread attention owing to their severe adverse health impacts. These produce enormous burden of disease and are associated with high economic cost especially in developed countries. Environmental pollutants causing endocrine disruption include pesticides, industrial wastes, packaging materials, food constituents, plastics, and cosmetic products. Likewise, pharmaceutical drugs have the endocrine disrupting potential through a wide array of mechanisms. Antipsychotic, antiepileptic, antihypertensive, antiviral, antidiabetic, and anticancer drugs are among the foremost non-hormonal endocrine disruptors. Several drugs affect thyroid hormone synthesis via interaction with iodine uptake to the release of T3 and T4 by thyrocytes. Prolonged use of some drugs increase susceptibility to diabetes mellitus either by direct destruction of β cells or enhanced insulin resistance. Other drugs may cause serious developmental defects in male or female reproductive system. Appropriate understanding of the mechanisms of endocrine disruption associated with non-hormonal drugs will guide future drug development and help us prevent and cure endocrine-related toxicity of pharmaceuticals. Therefore, this review focuses on endocrine disruption by pharmaceutical drugs as their side effect.

Identification, pathophysiology, and clinical implications of primary insulin hypersecretion in nondiabetic adults and adolescents

BACKGROUND

Excessive insulin secretion may lead to glucose dysregulation. Our aim was to identify primary (independent of insulin resistance) insulin hypersecretion in subjects with normal glucose tolerance and its role in the progression of dysglycemia.

METHODS

In 1,168 adults, insulin secretion rate (ISR) and β cell function were estimated by C-peptide modeling during an oral glucose tolerance test (OGTT) and an i.v. glucose tolerance test. Whole-body insulin sensitivity was measured by a hyperinsulinemic-euglycemic clamp. After regressing ISR on insulin sensitivity, subjects in the upper tertile of the distribution of residuals were defined as primary hypersecretors. This approach was applied to a biethnic cohort of 182 obese adolescents, who received an OGTT, a hyperglycemic, and a euglycemic clamp.

RESULTS

Adult hypersecretors showed older age, more familial diabetes, sedentary lifestyle, increased fat mass, and worse lipid profile compared with the rest of the cohort, despite virtually identical BMI and insulin sensitivity. Insulin secretion was increased by 53% due to enhanced (+23%) β cell glucose sensitivity. Despite the resulting hyperinsulinemia, glucose tolerance was worse in hypersecretors among both adults and adolescents, coupled with higher indices of liver insulin resistance and increased availability of gluconeogenic substrates. At the 3-year follow-up, adult hypersecretors had increased incidence of impaired glucose tolerance/type 2 diabetes.

CONCLUSION

Primary insulin hypersecretion, independent of insulin resistance, is associated with a worse clinical and metabolic phenotype in adults and adolescents and predicts deterioration of glucose control over time.

FUNDING

The relationship between insulin sensitivity and cardiovascular disease (RISC) Study was partly supported by EU grant QLG1-CT-2001-01252.

Reduced body weight at weaning followed by increased post-weaning growth rate interacts with part-per-trillion fetal serum concentrations of bisphenol A (BPA) to impair glucose tolerance in male mice

There is evidence from longitudinal studies that being light at birth and weaning is associated with subsequent rapid weight gain in infants. This is referred to as “centile crossing”, which can lead to increased risk of lifetime obesity, glucose dysregulation and type 2 diabetes. Here, pregnant CD-1 mice were hemi-ovariectomized so that the entire litter was contained in one uterine horn to increase variability in fetal growth rate. Pregnant females were implanted on gestation day (GD) 9 with a Silastic capsule containing 6, 60 or 600 μg bisphenol A (BPA). On GD 18 the mean fetal serum unconjugated BPA concentrations were 17, 177 and 1858 pg/ml, respectively. Capsules were not removed, to avoid maternal stress, and were predicted to release BPA for at least 3 weeks. Body weight at weaning was strongly negatively correlated with post-weaning weight gain in both control and BPA-treated male mice, consistent with human data; female offspring were excluded, avoiding complications associated with postpubertal estrogens. Within each treatment group, male offspring were sorted into tertiles based on relative weight gain during the two weeks after weaning, designated as having Rapid (R), Medium (M) or Slow (S) growth rate. BPA exposure was associated with altered growth rate between weaning and postnatal week 12 (young adulthood), when a low-dose (20 mg/kg, i.p.) glucose tolerance test (GTT) was performed. We found altered glucose regulation in response to all doses of BPA. However, glucose tolerance was only significantly impaired (blood glucose levels were elevated) compared to controls in males in the rapid post-weaning growth group exposed perinatally to BPA. We conclude that male mice that are light at weaning, but then experience rapid catch-up growth immediately after weaning, represent a sensitive sub-population that is vulnerable to the metabolic disrupting effects of very low pg/ml fetal serum concentrations of BPA.

Effects of perinatal exposure to BPA and its alternatives (BPS, BPF and BPAF) on hepatic lipid and glucose homeostasis in female mice adolescent offspring

The widespread application of bisphenols (BPs) makes them ubiquitous in the natural environment and poses many potential risks. In this study, we examined the effects of perinatal exposure to BPA and its 3 alternatives (BPS, BPF, and BPAF) on lipid and glucose homeostasis in female mice adolescent offspring. Specifically, BPA exposure promoted the expression of hepatic lipid synthesis and fatty acid accumulation genes, resulting in a significant increase in 2 free fatty acids contents. BPS exposure caused an increase in 6 free fatty acids and triglyceride contents through promoting the expression of fatty acid synthesis, triglyceride synthesis and fatty acid accumulation genes and inhibiting the expression of fatty acid β-oxidation genes. Interestingly, BPAF exposure showed completely opposite effects on hepatic lipid metabolism compared to BPS exposure. 9 free fatty acids and triglycerides contents in the liver were significantly reduced. In particular, BPF exposure caused decreases in 2 free fatty acids contents, but no significant changes were found in the genes for lipid metabolism. In addition, unlike BPA and BPF exposure, BPS and BPAF exposure also resulted in significant increases in glucose and glycogen contents in the liver by activation of Fxr-Shp pathway and glycolysis, and inhibition of gluconeogenesis. The results showed that compared to BPA and BPF exposure, BPS and BPAF exposure significantly regulated the expression of genes related to glucose and lipid metabolism and severely interfered with hepatic lipid and glucose homeostasis. This suggested that we should thoroughly evaluate the potential health risks of BPA and its alternatives.

Association between urinary tin concentration and diabetes in nationally representative sample of US adults

BACKGROUND

Animal studies indicate that chronic exposure to certain tin compounds induces pancreatic islet cell apoptosis and glucose intolerance. However, little is known about the health effects of environmental tin exposure in humans. Therefore, we evaluated the association of tin exposure with diabetes in a nationally representative sample of US adults.

METHODS

We used data from a nationally representative population (n = 3371) in the National Health and Nutrition Examination Survey 2011-14. Diabetes (n = 605) was defined as self-reported physician's diagnosis, HbA1c ≥6.5%, fasting plasma glucose ≥126 mg/dL, or 2-h plasma glucose ≥200 mg/dL. Tin concentrations in urine samples were determined by inductively coupled plasma mass spectrometry. Logistic regression with sample weights was used to estimate the odds ratios (ORs) of diabetes and 95% confidence intervals (CIs).

RESULTS

Urinary tin concentrations were higher in individuals with diabetes (weighted median 0.58 μg/L) than those without diabetes (0.39 μg/L). After adjustment for urinary creatinine and other diabetes risk factors, the OR of diabetes comparing the highest with lowest quartile of urinary tin concentrations was 1.6 (95% CI 1.0-2.6; P_trend  = 0.02).

CONCLUSIONS

Environmental tin exposure was positively and significantly associated with diabetes in US adults.

A Cross-Sectional Investigation of Cardiovascular and Metabolic Biomarkers among Conventional and Organic Farmers in Thailand

Pesticide exposure has been implicated as a risk factor for developing a wide range of adverse health issues. Some examples are metabolic syndromes, including diabetes. This study investigated the relationship between current occupational use of pesticides and metabolic and cardiovascular biomarker levels among organic and conventional farmers in Thailand. In total, 436 recruited farmers were divided into two groups: conventional farmers (n = 214) and organic farmers (n = 222). Participants, free of diabetes, were interviewed and submitted to a physical examination. Serum samples were collected for clinical laboratory analyses, i.e., serum glucose and lipid profiles (triglycerides, total cholesterol, high-density lipoproteins, and low-density lipoproteins). Potential risk factors such as smoking, alcohol consumption, and heavy exercise were significantly different between the two groups. There were significant differences in terms of the years of pesticide use, pesticide use at home, sources of drinking water, and distance between the farmers’ homes and farms between the groups. After adjusting for confounders, current conventional farmers had significantly higher abnormal body mass index (BMI), waist circumference, body fat percentage (% body fat), triglyceride, total cholesterol, and low-density lipoprotein values as compared to organic farmers. Conventional farmers had higher risk of many metabolic and cardiovascular risk factors as compared to organic farmers, putting them at higher risk of metabolic diseases in the future.

Mitochondria as target of endocrine-disrupting chemicals: implications for type 2 diabetes

Type 2 diabetes is a chronic, heterogeneous syndrome characterized by insulin resistance and pancreatic β-cell dysfunction or death. Among several environmental factors contributing to type 2 diabetes development, endocrine-disrupting chemicals (EDCs) have been receiving special attention. These chemicals include a wide variety of pollutants, from components of plastic to pesticides, with the ability to modulate endocrine system function. EDCs can affect multiple cellular processes, including some related to energy production and utilization, leading to alterations in energy homeostasis. Mitochondria are primarily implicated in cellular energy conversion, although they also participate in other processes, such as hormone secretion and apoptosis. In fact, mitochondrial dysfunction due to reduced oxidative capacity, impaired lipid oxidation and increased oxidative stress has been linked to insulin resistance and type 2 diabetes. Herein, we review the main mechanisms whereby metabolism-disrupting chemical (MDC), a subclass of EDCs that disturbs energy homeostasis, cause mitochondrial dysfunction, thus contributing to the establishment of insulin resistance and type 2 diabetes. We conclude that MDC-induced mitochondrial dysfunction, which is mainly characterized by perturbations in mitochondrial bioenergetics, biogenesis and dynamics, excessive reactive oxygen species production and activation of the mitochondrial pathway of apoptosis, seems to be a relevant mechanism linking MDCs to type 2 diabetes development.

Identification of a xenobiotic as a potential environmental trigger in primary biliary cholangitis

BACKGROUND & AIMS

Primary biliary cholangitis (PBC) is an autoimmune-associated chronic liver disease triggered by environmental factors, such as exposure to xenobiotics, which leads to a loss of tolerance to the lipoic acid-conjugated regions of the mitochondrial pyruvate dehydrogenase complex, typically to the E2 component. We aimed to identify xenobiotics that might be involved in the environmental triggering of PBC.

METHODS

Urban landfill and control soil samples from a region with high PBC incidence were screened for xenobiotic activities using analytical, cell-based xenobiotic receptor activation assays and toxicity screens.

RESULTS

A variety of potential xenobiotic classes were ubiquitously present, as identified by their interaction with xenobiotic receptors - aryl hydrocarbon receptor, androgen receptor and peroxisome proliferator activated receptor alpha - in cell-based screens. In contrast, xenoestrogens were present at higher levels in soil extracts from around an urban landfill. Furthermore, two landfill sampling sites contained a chemical(s) that inhibited mitochondrial oxidative phosphorylation and induced the apoptosis of a hepatic progenitor cell. The mitochondrial effect was also demonstrated in human liver cholangiocytes from three separate donors. The chemical was identified as the ionic liquid [3-methyl-1-octyl-1H-imidazol-3-ium]+ (M8OI) and the toxic effects were recapitulated using authentic pure chemical. A carboxylate-containing human hepatocyte metabolite of M8OI, bearing structural similarity to lipoic acid, was also enzymatically incorporated into the E2 component of the pyruvate dehydrogenase complex via the exogenous lipoylation pathway in vitro.

CONCLUSIONS

These results identify, for the first time, a xenobiotic in the environment that may be related to and/or be a component of an environmental trigger for PBC. Therefore, further study in experimental animal models is warranted, to determine the risk of exposure to these ionic liquids.

LAY SUMMARY

Primary biliary cholangitis is a liver disease in which most patients have antibodies to mitochondrial proteins containing lipoic acid binding site(s). This paper identified a man-made chemical present in soils around a waste site. It was then shown that this chemical was metabolized into a product with structural similarity to lipoic acid, which was capable of replacing lipoic acid in mitochondrial proteins.

Dietary Exposure to the Environmental Chemical, PFOS on the Diversity of Gut Microbiota, Associated With the Development of Metabolic Syndrome

The gut microbiome is a dynamic ecosystem formed by thousands of diverse bacterial species. This bacterial diversity is acquired early in life and shaped over time by a combination of multiple factors, including dietary exposure to distinct nutrients and xenobiotics. Alterations of the gut microbiota composition and associated metabolic activities in the gut are linked to various immune and metabolic diseases. The microbiota could potentially interact with xenobiotics in the gut environment as a result of their board enzymatic capacities and thereby affect the bioavailability and toxicity of the xenobiotics in enterohepatic circulation. Consequently, microbiome-xenobiotic interactions might affect host health. Here, we aimed to investigate the effects of dietary perfluorooctane sulfonic acid (PFOS) exposure on gut microbiota in adult mice and examine the induced changes in animal metabolic functions. In mice exposed to dietary PFOS for 7 weeks, body PFOS and lipid contents were measured, and to elucidate the effects of PFOS exposure, the metabolic functions of the animals were assessed using oral glucose-tolerance test and intraperitoneal insulin-tolerance and pyruvate-tolerance tests; moreover, on Day 50, cecal bacterial DNA was isolated and subject to 16S rDNA sequencing. Our results demonstrated that PFOS exposure caused metabolic disturbances in the animals, particularly in lipid and glucose metabolism, but did not substantially affect the diversity of gut bacterial species. However, marked modulations were detected in the abundance of metabolism-associated bacteria belonging to the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Cyanobacteria, including, at different taxonomic levels, Turicibacteraceae, Turicibacterales, Turicibacter, Dehalobacteriaceae, Dehalobacterium, Allobaculum, Bacteroides acidifaciens, Alphaproteobacteria, and 4Cod-2/YS2. The results of PICRUSt analysis further indicated that PFOS exposure perturbed gut metabolism, inducing notable changes in the metabolism of amino acids (arginine, proline, lysine), methane, and a short-chain fatty acid (butanoate), all of which are metabolites widely recognized to be associated with inflammation and metabolic functions. Collectively, our study findings provide key information regarding the biological relevance of microbiome-xenobiotic interactions associated with the ecology of gut microbiota and animal energy metabolism.

Maternal lipopolysaccharide exposure results in glucose metabolism disorders and sex hormone imbalance in male offspring

An adverse intrauterine environment may be an important factor contributing to the development of type 2 diabetes in later life. The present study investigated the longitudinal effects of maternal lipopolysaccharide (LPS) exposure during the third trimester on glucose metabolism and sex hormone balance in the offspring. Pregnant mice were intraperitoneally injected with LPS (50 μg/kg) daily from gestational day (GD) 15 to GD17. Glucose tolerance test (GTT) and insulin tolerance test (ITT) were assessed at postnatal day (PND) 60 and PND120. Sex hormones, their receptors, and metabolic enzymes (aromatase) were measured in male offspring at different phases of development (PND14: juvenile; PND35: adolescence; PND60: adulthood; and PND120: middle age). LPS-exposed male offspring exhibited glucose intolerance and insulin resistance by GTT and ITT at middle age, accompanied by an increase in fasting blood glucose and reductions in serum insulin levels and hepatic phosphorylated (p) -AKT/AKT ratio. However, glucose intolerance and insulin resistance were not observed in LPS-exposed female offspring. Maternal LPS exposure upregulated hepatic aromatase proteins and mRNA levels in male offspring at all time points. At adolescence, the testosterone/estradiol ratio (T/E2) was markedly reduced in LPS-exposed male offspring. Moreover, maternal LPS exposure significantly increased hepatic estrogen receptor (ER) α expressions and decreased hepatic androgen receptor (AR) expressions in male offspring. At adulthood, maternal LPS exposure increased serum estradiol levels, decreased serum testosterone levels and elevated hepatic ERβ expressions in male offspring. In conclusion, maternal LPS exposure upregulated aromatase expressions, followed by a reduction in the T/E2 ratio and an alteration in sex hormone receptor activity, which might be involved in the development of glucose metabolism disorders in middle-aged male offspring. This study provides a novel clue and direction to clarify the pathogenesis of maternal infection-related diabetes in male offspring.

Experimental BPA Exposure and Glucose-Stimulated Insulin Response in Adult Men and Women

Context

Human cross-sectional and animal studies have shown an association of the chemical bisphenol A (BPA) with insulin resistance, type 2 diabetes, and other metabolic diseases, but no human experimental study has investigated whether BPA alters insulin/C-peptide secretion.

Design

Men and postmenopausal women (without diabetes) were orally administered either the vehicle or a BPA dose of 50 µg/kg body weight, which has been predicted by US regulators (Food and Drug Administration, Environmental Protection Agency) to be the maximum, safe daily oral BPA dose over the lifetime. Insulin response was assessed in two cross-over experiments using an oral glucose tolerance test (OGTT; experiment 1) and a hyperglycemic (HG) clamp (experiment 2). Main outcomes were the percentage change of BPA session measures relative to those of the control session.

Results

Serum bioactive BPA after experimental exposure was at levels detected in human biomonitoring studies. In the OGTT, a strong positive correlation was found between hemoglobin A1c(HbA1c) and the percentage change in the insulinogenic index (Spearman = 0.92), an indicator of early-phase insulin response, and the equivalent C-peptide index (Pearson = 0.97). In the HG clamp study, focusing on the later-phase insulin response to a stable level of glucose, several measures of insulin and C-peptide appeared suppressed during the BPA session relative to the control session; the change in insulin maximum concentration (Cmax) was negatively correlated with HbA1c and the Cmax of bioactive serum BPA.

Conclusions

This exploratory study suggests that BPA exposure to a dose considered safe by US regulators may alter glucose-stimulated insulin response in humans.

The LIFE PERSUADED project approach on phthalates and bisphenol A biomonitoring in Italian mother-child pairs linking exposure and juvenile diseases

Phthalates and bisphenol A (BPA), plasticizers used in several products of daily life, are considered as endocrine disrupters, therefore children exposure is particularly relevant. The LIFE PERSUADED project aims to define the following: (a) the evaluation of internal levels of DEHP's metabolites and BPA in Italian children and their mothers, (b) the association of the exposure with puberty development and obesity diseases, and (c) the effects of exposure in juvenile in vivo model. The cross-sectional study has involved 2160 mother-child pairs, including males and females, children and adolescents, from urban and rural areas of North, Center, and South Italy. A structured questionnaire and a food diary are designed to evaluate the association between lifestyle variables potentially related to DEHP/BPA exposure and internal levels, through univariate and multivariate analyses. Two pilot case-control studies are carried out on idiopathic premature thelarche and precocious puberty (30 girls each group, aged 2-7 years) and idiopathic obesity (30 boys and 30 girls, aged 6-10 years), matched to healthy controls. BPA and DEHP's metabolites are analyzed in urine samples from all recruited subjects. Clinical and toxicological biomarkers are evaluated in serum of case-control subjects. Moreover, the toxicity study is carried out in a juvenile rodent model exposed to mixtures of BPA and DEHP at dose levels recorded in children population. The scientific results of LIFE PERSUADED will contribute to risk assessment of BPA and DEHP.

Exposure of adipocytes to bisphenol-A in vitro interferes with insulin action without enhancing adipogenesis

Bisphenol-A (BPA) is a lipophilic compound widely used in the manufacture of plastic items and thought to play a role in the growing obesity epidemic. Recent publications suggest that BPA may have a pro-adipogenic effect. Here we explore the effect of low, but environmentally relevant, concentrations of BPA on adipogenesis using a variety of cellular models. Mouse 3T3-L1, C3H10T1/2 and human adipose-derived stromal cells (hADSCs) were cultured with BPA concentrations ranging from 0.1nM to 100μM. We failed to observe positive effects on differentiation at any dose or in any model. 3T3-L1 adipocytes differentiated with high concentrations of BPA showed decreased mRNA expression of several adipocyte markers. Mature adipocytes differentiated in the presence of BPA were insulin resistant, with an approximate 25% reduction in insulin-stimulated glucose uptake. This was accompanied by a significant decrease in insulin-stimulated Akt phosphorylation, and an increase in mRNA levels of inflammatory markers (i.e. IL-6, TNFα). In conclusion, low, but environmentally relevant, doses of BPA may contribute to the development of a chronic, low-grade inflammatory state in exposed adipocytes, which in turn may affect adipose tissue insulin sensitivity, independent of adipogenesis. These studies suggest an alternative mechanism by which BPA may contribute to the development of obesity.

Circadian dysrhythmia-linked diabetes mellitus: Examining melatonin’s roles in prophylaxis and management

Diabetes mellitus is a chronic, life-threatening metabolic disorder that occurs worldwide. Despite an increase in the knowledge of the risk factors that are associated with diabetes mellitus, its worldwide prevalence has continued to rise; thus, necessitating more research into its aetiology. Recent researches are beginning to link a dysregulation of the circadian rhythm to impairment of intermediary metabolism; with evidences that circadian rhythm dysfunction might play an important role in the aetiology, course or prognosis of some cases of diabetes mellitus. These evidences thereby suggest possible relationships between the circadian rhythm regulator melatonin, and diabetes mellitus. In this review, we discuss the roles of the circadian rhythm in the regulation of the metabolism of carbohydrates and other macronutrients; with emphasis on the importance of melatonin and the impacts of its deficiency on carbohydrate homeostasis. Also, the possibility of using melatonin and its analogs for the “prophylaxis” or management of diabetes mellitus is also considered.

Environmental Xenoestrogens Super-Activate a Variant Murine ER Beta in Cholangiocytes

High systemic levels of oestrogens are cholestatic and primary biliary cholangitis (PBC)-which is characterized by hepatic ductular inflammation-is thought to be triggered by exposure to xenobiotics such as those around landfill sites. Xenoestrogens may be a component of this chemical trigger. We therefore hypothesized that xenoestrogens are present at higher levels in the proximity of landfill sites. To test this hypothesis, soil samples were collected, extracts prepared and biological oestrogenic activity examined using cell-based reporter gene assays. Extracts from several sample sites around a landfill site contained a chemical(s) which activated the human ERα in a dose-dependent manner. Extracts from 3 separate control sampling sites were absent of any detectable activity. The mouse ERα and 2 variant mouse ERβ cDNAs were cloned and extracts from sample sites around a landfill site also activated these receptors. One variant murine ERβ was constitutively active when expressed in cholangiocytes, was readily inactivated by ICI182780 and activated in a dose-responsive, ICI182780-inhibitable manner by oestrogen. However, when this receptor was activated by extracts from landfill site soils, ICI182780 failed to antagonize activation. ERβ was readily detectable in murine cholangiocytes and exposing mice acutely to a pooled ER activating soil extracts also gave rise to a mild cholestatic injury. These data indicate that the environment around landfill sites may contain higher levels of xenoestrogens; that these chemicals have "super-activating" characteristics with a variant ERβ and therefore these chemicals could be a component of a xenobiotic insult that triggers PBC.

Extranuclear-initiated estrogenic actions of endocrine disrupting chemicals: Is there toxicology beyond paracelsus?

Endocrine Disrupting Chemicals (EDCs), including bisphenol-A (BPA) do not act as traditional toxic chemicals inducing massive cell damage or death in an unspecific manner. EDCs can work upon binding to hormone receptors, acting as agonists, antagonists or modulators. Bisphenol-A displays estrogenic activity and, for many years it has been classified as a weak estrogen, based on the classic transcriptional action of estrogen receptors serving as transcription factors. However, during the last two decades our knowledge about estrogen signaling has advanced considerably. It is now accepted that estrogen receptors ERα and ERβ activate signaling pathways outside the nucleus which may or may not involve transcription. In addition, a new membrane estrogen receptor, GPER, has been proposed. Pharmacological and molecular evidence, along with results obtained in genetically modified mice, demonstrated that BPA, and its substitute BPS, are potent estrogens acting at nanomolar concentrations via extranuclear ERα, ERβ, and GPER. The different signaling pathways activated by BPA and BPS explain the well-known estrogenic effects of low doses of EDCs as well as non-monotonic dose-response relationships. These signaling pathways may help to explain the actions of EDCs with estrogenic activity in the etiology of different pathologies, including type-2 diabetes and obesity.

Long-term oral exposure to safe dose of bisphenol A in association with high-fat diet stimulate the prostatic lesions in a rodent model for prostate cancer

BACKGROUND

Studies have shown that exposure to environmental chemicals known as endocrine disruptors can cause permanent changes in genital organs, such as the prostate. Among these environmental chemicals stands out bisphenol A (BPA). Another factor associated with prostate changes is the consumption of a high-fat diet. Although the relationship between the consumption of a high-fat diet and an increased risk of prostate cancer is well established, the mechanisms that lead to the establishment of this disease are not completely understood, nor the simultaneous action of BPA and high-fat diet.

METHODS

Adult gerbils (100 days old) were divided in four groups (n = 6 per group): Control (C): animals that received a control diet and filtered water; Diet (D): animals that received a high-fat diet and filtered water; BPA: animals that received a control diet and BPA - 50 µg kg^-1 day^-1 in drinking water; BPA + Diet (BPA + D): animals that received a high-fat diet + BPA - 50 µg kg^-1 day^-1 in drinking water. After the experimental period (6 months), the dorsolateral and ventral prostate lobes were removed, and analyzed by several methods.

RESULTS

Histological analysis indicated premalignant and malignant lesions in both prostatic lobes. However, animals of the D, BPA, and BPA + D groups showed a higher incidence and larger number of prostatic lesions; inflammatory foci were also common. Markers to assess prostate lesions, such as increased activation of the DNA repair system (PCNA-positive cells), androgen receptor (AR), and number of basal cells, confirmed the histology. However, serum levels of testosterone did not change under the experimental conditions.

CONCLUSIONS

The results indicated that the methodology used was effective in generating metabolic changes, which directly compromised prostatic homeostasis. Diet and BPA appear to modulate the activation of the AR pathway and thereby optimize tumor establishment in the gerbil prostate.

Emergent contaminants: Endocrine disruptors and their laccase-assisted degradation - A review

Herein, an effort has been made to highlight the trends of the state-of-the-art of laccase-assisted degradation of emerging contaminants at large and endocrine disruptors in particular. Since first described in the 19th century, laccase has received particular interest for inter- and multidisciplinary investigations due to its uniqueness and remarkable biotechnological applicability. There has always been a paramount concern over the widespread occurrences of various pollutant types, around the globe. Therefore, pollution free processes are gaining ground all over the world. With ever increasing scientific knowledge, socioeconomic awareness, human health-related issues and ecological apprehensions, people are more concerned about the widespread environmental pollutants. In this context, the occurrences of newly identified pollutants so-called "emerging contaminants - ECs" in our main water bodies is of continued and burning concern worldwide. Undoubtedly, various efforts have already been made to tackle this challenging ECs concern though using different approaches including physical and chemical, however, each has considerable limitations. In this review, we present information on how laccase-assisted approach can change this limited tendency of physical and chemical based approaches. A special focus has been given to the laccase-assisted systems including pristine laccase, laccase-mediator catalyzed system and immobilized-laccase catalyzed system that promotes the endocrine disruptors removal. Towards the end, a list of outstanding questions and research gaps are given that can pave the way for future studies.

Scaffold-free generation of uniform adipose spheroids for metabolism research and drug discovery

Adipose tissue dysfunction is critical to the development of type II diabetes and other metabolic diseases. While monolayer cell culture has been useful for studying fat biology, 2D culture often does not reflect the complexity of fat tissue. Animal models are also problematic in that they are expensive, time consuming, and may not completely recapitulate human biology because of species variation. To address these problems, we have developed a scaffold-free method to generate 3D adipose spheroids from primary or immortal human or mouse pre-adipocytes. Pre-adipocytes self-organize into spheroids in hanging drops and upon transfer to low attachment plates, can be maintained in long-term cultures. Upon exposure to differentiation cues, the cells mature into adipocytes, accumulating large lipid droplets that expand with time. The 3D spheroids express and secrete higher levels of adiponectin compared to 2D culture and respond to stress, either culture-related or toxin-associated, by secreting pro-inflammatory adipokines. In addition, 3D spheroids derived from brown adipose tissue (BAT) retain expression of BAT markers better than 2D cultures derived from the same tissue. Thus, this model can be used to study both the maturation of pre-adipocytes or the function of mature adipocytes in a 3D culture environment.

β-Cell Failure or β-Cell Abuse?

This review is motivated by the need to question dogma that has not yielded significant improvements in outcomes of Type 2 Diabetes treatment: that insulin resistance is the driver of ß-Cell failure and resulting hyperglycemia. We highlight the fact that hyperlipidemia, insulin resistance, and hyperinsulinemia all precede overt diabetes diagnosis and can each induce the other when tested experimentally. New research highlights the importance of high levels of circulating insulin as both a driver of weight gain and insulin resistance. Data from our lab and others document that several nutrients and environmental toxins can stimulate insulin secretion at non-stimulatory glucose in the absence of insulin resistance. This occurs either by direct action on the ß-Cell or by shifting its sensitivity to known secretagogues. We raise the next logical question of whether ß-Cell dysfunction in Type 2 Diabetes is due to impaired function, defined as failure, or if chronic overstimulation of the ß-Cell that exceeds its capacity to synthesize and secrete insulin, defined as abuse, is the main abnormality in Type 2 Diabetes. These questions are important as they have direct implications for how to best prevent and treat Type 2 Diabetes.

Environmental Pollutants and Metabolic Disorders: The Multi-Exposure Scenario of Life

Obesity and diabetes have reached epidemic proportions the past few decades and continue to progress worldwide with no clear sign of decline of the epidemic. Obesity is of high concern because it is the main risk factor for a number of non-communicable diseases such as cardiovascular diseases and type 2 diabetes. Metabolic diseases constitute a major challenge as they are associated with an overall reduced quality of life and impose a heavy economic burden on countries. These are multifactorial diseases and it is now recognized that environmental exposure to man-made chemical pollutants is part of the equation. Yet, risk assessment procedures are based on a one-by-one chemical evaluation which does not meet the specificities of the multi-exposure scenario of life, e.g., a combined and long-term exposure to even the smallest amounts of chemicals. Indeed, it is assumed that environmental exposure to chemicals will be negligible based on the low potency of each chemical and that they do not interact. Within this mini-review, strong evidences are brought that exposure to low levels of multiple chemicals especially those shown to interfere with hormonal action, the so-called endocrine disrupting compounds do trigger metabolic disturbances in conditions in which no effect was expected if considering the concentration of each individual chemical in the mixture. This is known as the cocktail effect. It means that risk assessment procedures are not protective enough and thus that it should be revisited for the sake of Public Health.

Timing of Exposure and Bisphenol-A: Implications for Diabetes Development

Bisphenol-A (BPA) is one of the most widespread endocrine disrupting chemicals (EDCs). It is used as the base compound in the production of polycarbonate and other plastics present in many consumer products. It is also used as a building block in epoxy can coating and the thermal paper of cash register receipts. Humans are consistently exposed to BPA and, in consequence, this compound has been detected in the majority of individuals examined. Over the last decade, an enlarging body of evidence has provided a strong support for the role of BPA in the etiology of diabetes and other metabolic disorders. Timing of exposure to EDCs results crucial since it has important implications on the resulting adverse effects. It is now well established that the developing organisms are particularly sensitive to environmental influences. Exposure to EDCs during early life may result in permanent adverse consequences, which increases the risk of developing chronic diseases like diabetes in adult life. In addition to that, developmental abnormalities can be transmitted from one generation to the next, thus affecting future generations. More recently, it has been proposed that gestational environment may also program long-term susceptibility to metabolic disorders in the mother. In the present review, we will comment and discuss the contributing role of BPA in the etiology of diabetes. We will address the metabolic consequences of BPA exposure at different stages of life and comment on the final phenotype observed in different whole-animal models of study.

A Prospective Cohort Study of Prenatal Diethylstilbestrol Exposure and Cardiovascular Disease Risk

PURPOSE

Prenatal exposure to diethylstilbestrol (DES), a prototype endocrine-disrupting chemical, is associated with risk for adverse reproductive outcomes and cancer in women. We investigated whether cardiovascular disease (CVD) risk might also be greater in women prenatally exposed to DES.

METHODS

DES-exposed (n = 3941) and -unexposed (n = 1705) women participating in the Combined DES Cohort Follow-up Study were followed prospectively from 1994 to 2013. Prenatal DES exposure (or lack of exposure) was documented in the birth record or physician's note. Participants reported by questionnaire any "serious medical conditions requiring hospitalization, surgery or long-term treatment," including coronary artery disease (CAD), myocardial infarction (MI), and stroke. We sought physician's verification of self-reports and identified CVD deaths from the National Death Index. Hazard ratios (HRs) with 95% confidence intervals (CIs) from Cox proportional hazard regression models estimated associations between DES exposure and CVD incidence, adjusted for birth year, original cohort, and potential confounders.

RESULTS

In comparison of the exposed to the unexposed women, the HRs for reported conditions were 1.74 (95% CI, 1.03 to 2.93) for CAD, 2.20 (95% CI, 1.15 to 4.21) for MI, 1.01 (95% CI, 0.54 to 1.90) for stroke, and 1.31 (95% CI, 0.93 to 1.86) for the combined conditions (i.e., total CVD). The HRs were similar for verified outcomes (CAD, 1.72; MI, 2.67; stroke, 0.92; and total CVD, 1.25) and with additional adjustment for hypertension, diabetes, and high cholesterol (HRs: CAD, 1.67; MI, 2.04; stroke, 0.96; and total CVD, 1.24).

CONCLUSIONS

These data demonstrate associations in women who have prenatal DES exposure with CAD and MI, but not with stroke, which appear to be independent of established CVD risk factors.

Biological and Clinical Implications of Comorbidities in Parkinson's Disease

A wide spectrum of comorbidities has been associated with Parkinson's disease (PD), a progressive neurodegenerative disease that affects more than seven million people worldwide. Emerging evidence indicates that chronic diseases including diabetes, depression, anemia and cancer may be implicated in the pathogenesis and progression of PD. Recent epidemiological studies suggest that some of these comorbidities may increase the risk of PD and precede the onset of motor symptoms. Further, drugs to treat diabetes and cancer have elicited neuroprotective effects in PD models. Nonetheless, the mechanisms underlying the occurrence of these comorbidities remain elusive. Herein, we discuss the biological and clinical implications of comorbidities in the pathogenesis, progression, and clinical management, with an emphasis on personalized medicine applications for PD.

Late-Onset ADHD: Understanding the Evidence and Building Theoretical Frameworks

PURPOSE OF REVIEW

The traditional definition of Attention-Deficit/Hyperactivity Disorder (ADHD), assuming onset in childhood, has been challenged by evidence from four recent birth-cohort studies that reported most adults with ADHD lacked a childhood categorical ADHD diagnosis.

RECENT FINDINGS

Late onset of symptoms was evaluated in the long-term follow-up of the Multimodal Treatment study of ADHD (MTA). In most cases, other factors were present that discounted the late onset of ADHD symptoms and excluded the diagnosis of ADHD. We offer two theoretical frameworks for understanding the ADHD trajectory throughout the life cycle: (1) the complex phenotype model, and (2) the restricted phenotype model. We conclude that (a) late onset (after age 12) is a valid trajectory for ADHD symptoms, (b) the percentage of these cases with onset after adolescence is yet uncertain, and

Effects of bisphenol A treatment during pregnancy on kidney development in mice: a stereological and histopathological study

Bisphenol A (BPA) is a chemical found in plastics that resembles oestrogen in organisms. Developmental exposure to endocrine-disrupting chemicals, such as BPA, increases the susceptibility to type 2 diabetes (T2DM) and cardiovascular diseases. Animal studies have reported a nephron deficit in offspring exposed to maternal diabetes. The aim of this study was to investigate the prenatal BPA exposure effects on nephrogenesis in a mouse model that was predisposed to T2DM. This study quantitatively evaluated the renal structural changes using stereology and histomorphometry methods. The OF1 pregnant mice were treated with a vehicle or BPA (10 or 100 μg/kg/day) during days 9-16 of gestation (early nephrogenesis). The 30-day-old offspring were sacrificed, and tissue samples were collected and prepared for histopathological and stereology studies. Glomerular abnormalities and reduced glomerular formation were observed in the BPA offspring. The kidneys of the BPA10 and BPA100 female offspring had a significantly lower glomerular number and density than those of the CONTROL female offspring. The glomerular histomorphometry revealed a significant difference between the female and male CONTROL offspring for the analysed glomerular parameters that disappeared in the BPA10 and BPA100 offspring. In addition, the kidney histopathological examination showed typical male cuboidal epithelial cells of the Bowman capsule in the female BPA offspring. Exposure to environmentally relevant doses of BPA during embryonic development altered nephrogenesis. These structural changes could be associated with an increased risk of developing cardiometabolic diseases later in life.

Transcriptomic and Functional Analyses on the Effects of Dioxin on Insulin Secretion of Pancreatic Islets and β-Cells

In this study, transcriptomic and Ingenuity Pathway Analysis (IPA) underlined that an ex-vivo TCDD treatment (0.1 nM) stimulated insulin-release in mouse pancreatic islets via the effect on the Akt-mTOR-p70S6K, AMPK and ERK1/2 pathways. Functional studies using both ex-vivo islets and the mouse β-cell-line (Min-6) validated the stimulatory effects of TCDD (0.1 and 1 nM) on basal-insulin secretion. At 0.1 nM TCDD treatment on Min-6, Western blot analysis showed activation of ERK1/2 and decreased expression of pyruvate dehydrogenase kinase (PDK). A reduction of PDK expression is associated with an increase of pyruvate dehydrogenase flux. This observation was supported by the detection of significantly higher cellular ATP levels, an increase of glucose-stimulated-insulin-secretion (GSIS), and an inhibition of the AMPK pathway. At 1 nM TCDD treatment on Min-6, significant inhibitions of the Akt-mTOR pathway, cellular ATP production, and GSIS were evident. The experimental studies in Min-6 supported the IPA of transcriptomic data in pancreatic islets. Collectively, TCDD treatment caused an elevated basal-insulin release in both islets and β-cell cultures. Moreover, our data revealed that the modulation of the Akt-mTOR-p70S6K, AMPK and ERK1/2 pathways might be an important component of the mechanism for the TCDD-perturbing effects on ATP production in β-cells in affecting insulin secretion.

Molecular mechanisms involved in the non-monotonic effect of bisphenol-a on ca2+ entry in mouse pancreatic β-cells

In regulatory toxicology, the dose-response relationship is a key element towards fulfilling safety assessments and satisfying regulatory authorities. Conventionally, the larger the dose, the greater the response, following the dogma “the dose makes the poison”. Many endocrine disrupting chemicals, including bisphenol-A (BPA), induce non-monotonic dose response (NMDR) relationships, which are unconventional and have tremendous implications in risk assessment. Although several molecular mechanisms have been proposed to explain NMDR relationships, they are largely undemonstrated. Using mouse pancreatic β-cells from wild-type and oestrogen receptor ERβ−/− mice, we found that exposure to increasing doses of BPA affected Ca²⁺ entry in an NMDR manner. Low doses decreased plasma membrane Ca²⁺ currents after downregulation of Cav2.3 ion channel expression, in a process involving ERβ. High doses decreased Ca²⁺ currents through an ERβ-mediated mechanism and simultaneously increased Ca²⁺ currents via oestrogen receptor ERα. The outcome of both molecular mechanisms explains the NMDR relationship between BPA and Ca²⁺ entry in β-cells.

Adipose Tissue as a Site of Toxin Accumulation

We examine the role of adipose tissue, typically considered an energy storage site, as a potential site of toxicant accumulation. Although the production of most persistent organic pollutants (POPs) was banned years ago, these toxicants persist in the environment due to their resistance to biodegradation and widespread distribution in various environmental forms (e.g., vapor, sediment, and water). As a result, human exposure to these toxicants is inevitable. Largely due to their lipophilicity, POPs bioaccumulate in adipose tissue, resulting in greater body burdens of these environmental toxicants with obesity. POPs of major concern include polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs), and polybrominated biphenyls and diphenyl ethers (PBBs/PBDEs), among other organic compounds. In this review, we (i) highlight the physical characteristics of toxicants that enable them to partition into and remain stored in adipose tissue, (ii) discuss the specific mechanisms of action by which these toxicants act to influence adipocyte function, and (iii) review associations between POP exposures and the development of obesity and diabetes. An area of controversy relates to the relative potential beneficial versus hazardous health effects of toxicant sequestration in adipose tissue. © 2017 American Physiological Society. Compr Physiol 7:1085-1135, 2017.

Status of LEPR Gene in PCB-exposed Population: A Quick Look

Earlier, we have reported that Polychlorinated Biphenyls (PCBs) exposure in Slovak population has made differential gene expression that has linked to the possibilities of some diseases and disorder development in the studied population. Here we report that down-regulation of LEPR (Leptin receptor) gene in the 45-month children may have been following consequences in developing obesity later in life. A pilot high-throughput qRT-PCR [Taqman Low Density Array (TLDA)] study in a small population also corroborated the gene-expression results, and their pathways underlying the consequences of the diseases, amid further detailed large-scale population validation. The study shows the opportunity of predicting long-term effects of chemical exposures using selected genomic classifiers may reflect exposure effect and risk from environmental toxicants.

Endocrine-disrupting chemicals and the regulation of energy balance

Energy balance involves the adjustment of food intake, energy expenditure and body fat reserves through homeostatic pathways. These pathways include a multitude of biochemical reactions, as well as hormonal cues. Dysfunction of this homeostatic control system results in common metabolism-related pathologies, which include obesity and type 2 diabetes mellitus. Metabolism-disrupting chemicals (MDCs) are a particular class of endocrine-disrupting chemicals that affect energy homeostasis. MDCs affect multiple endocrine mechanisms and thus different cell types that are implicated in metabolic control. MDCs affect gene expression and the biosynthesis of key enzymes, hormones and adipokines that are essential for controlling energy homeostasis. This multifaceted spectrum of actions precludes compensatory responses and favours metabolic disorders. Herein, we review the main mechanisms used by MDCs to alter energy balance. This work should help to identify new MDCs, as well as novel targets of their action.

MiR-338 controls BPA-triggered pancreatic islet insulin secretory dysfunction from compensation to decompensation by targeting Pdx-1

Bisphenol A (BPA) can disrupt glucose homeostasis and impair pancreatic islet function; however, the mechanisms behind these effects are poorly understood. Male mice (4 wk old) were treated with BPA (50 or 500 μg/kg/d) for 8 wk. Whole-body glucose homeostasis, pancreatic islet morphology and function, and miR-338-mediated molecular signal transduction analyses were examined. We showed that BPA treatment led to a disruption of glucose tolerance and a compensatory increase of pancreatic islets insulin secretion and pancreatic and duodenal homeobox 1 (Pdx1) expression in mice. Inhibition of Pdx1 reduced glucose-stimulated insulin secretion and ATP production in the islets of BPA-exposed mice. Based on primary pancreatic islets, we also confirmed that miR-338 regulated Pdx1 and thus contributed to BPA-induced insulin secretory dysfunction from compensation to decompensation. Short-term BPA exposure downregulated miR-338 through activation of G-protein-coupled estrogen receptor 1 (Gpr30), whereas long-term BPA exposure upregulated miR-338 through suppression of glucagon-like peptide 1 receptor (Glp1r). Taken together, our results reveal a molecular mechanism, whereby BPA regulates Gpr30/Glp1r to mediate the expression of miR-338, which acts to control Pdx1-dependent insulin secretion. The Gpr30/Glp1r-miR-338-Pdx1 axis should be represented as a novel mechanism by which BPA induces insulin secretory dysfunction in pancreatic islets.-Wei, J., Ding, D., Wang, T., Liu, Q., Lin, Y. MiR-338 controls BPA-triggered pancreatic islet insulin secretory dysfunction from compensation to decompensation by targeting Pdx-1.

Endocrine-disrupting chemicals and fatty liver disease

A growing epidemic of nonalcoholic fatty liver disease (NAFLD) is paralleling the increase in the incidence of obesity and diabetes mellitus in countries that consume a Western diet. As NAFLD can lead to life-threatening conditions such as cirrhosis and hepatocellular carcinoma, an understanding of the factors that trigger its development and pathological progression is needed. Although by definition this disease is not associated with alcohol consumption, exposure to environmental agents that have been linked to other diseases might have a role in the development of NAFLD. Here, we focus on one class of these agents, endocrine-disrupting chemicals (EDCs), and their potential to influence the initiation and progression of a cascade of pathological conditions associated with hepatic steatosis (fatty liver). Experimental studies have revealed several potential mechanisms by which EDC exposure might contribute to disease pathogenesis, including the modulation of nuclear hormone receptor function and the alteration of the epigenome. However, many questions remain to be addressed about the causal link between acute and chronic EDC exposure and the development of NAFLD in humans. Future studies that address these questions hold promise not only for understanding the linkage between EDC exposure and liver disease but also for elucidating the molecular mechanisms that underpin NAFLD, which in turn could facilitate the development of new prevention and treatment opportunities.

In Vitro Toxicity Testing of Food Contact Materials: State-of-the-Art and Future Challenges

Currently, toxicological testing of food contact materials (FCMs) is focused on single substances and their genotoxicity. However, people are exposed to mixtures of chemicals migrating from food contact articles (FCAs) into food, and toxic effects other than genotoxic damage may also be relevant. Since FCMs can be made of more than 8 thousand substances, assessing them one-by-one is very resource-consuming. Moreover, finished FCAs usually contain non-intentionally added substances (NIAS). NIAS toxicity can only be tested if a substance's chemical identity is known and if it is available as a pure chemical. Often, this is not the case. Nonetheless, regulations require safety assessments for all substances migrating from FCAs, including NIAS, hence new approaches to meet this legal obligation are needed. Testing the overall migrate or extract from an FCM/FCA is an option. Ideally, such an assessment would be performed by means of in vitro bioassays, as they are rapid and cost-effective. Here, we review the studies using in vitro bioassays to test toxicity of FCMs/FCAs. Three main categories of in vitro assays that have been applied include assays for cytotoxicity, genotoxicity, and endocrine disruption potential. In addition, we reviewed studies with small multicellular animal-based bioassays. Our overview shows that in vitro testing of FCMs is in principle feasible. We discuss future research needs and FCM-specific challenges. Sample preparation procedures need to be optimized and standardized. Further, the array of in vitro tests should be expanded to include those of highest relevance for the most prevalent human diseases of concern.

Adipose tissue dysfunction as a central mechanism leading to dysmetabolic obesity triggered by chronic exposure to p,p'-DDE

Endocrine-disrupting chemicals such as p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE), are bioaccumulated in the adipose tissue (AT) and have been implicated in the obesity and diabetes epidemic. Thus, it is hypothesized that p,p’-DDE exposure could aggravate the harm of an obesogenic context. We explored the effects of 12 weeks exposure in male Wistar rats’ metabolism and AT biology, assessing a range of metabolic, biochemical and histological parameters. p,p’-DDE -treatment exacerbated several of the metabolic syndrome-accompanying features induced by high-fat diet (HF), such as dyslipidaemia, glucose intolerance and hypertension. A transcriptome analysis comparing mesenteric visceral AT (vAT) of HF and HF/DDE groups revealed a decrease in expression of nervous system and tissue development-related genes, with special relevance for the neuropeptide galanin that also revealed DNA methylation changes at its promoter region. Additionally, we observed an increase in transcription of dipeptidylpeptidase 4, as well as a plasmatic increase of the pro-inflammatory cytokine IL-1β. Our results suggest that p,p’-DDE impairs vAT normal function and effectively decreases the dynamic response to energy surplus. We conclude that p,p’-DDE does not merely accumulate in fat, but may contribute significantly to the development of metabolic dysfunction and inflammation. Our findings reinforce their recognition as metabolism disrupting chemicals, even in non-obesogenic contexts.

Endocrine disrupting chemicals in mixture and obesity, diabetes and related metabolic disorders

Obesity and associated metabolic disorders represent a major societal challenge in health and quality of life with large psychological consequences in addition to physical disabilities. They are also one of the leading causes of morbidity and mortality. Although, different etiologic factors including excessive food intake and reduced physical activity have been well identified, they cannot explain the kinetics of epidemic evolution of obesity and diabetes with prevalence rates reaching pandemic proportions. Interestingly, convincing data have shown that environmental pollutants, specifically those endowed with endocrine disrupting activities, could contribute to the etiology of these multifactorial metabolic disorders. Within this review, we will recapitulate characteristics of endocrine disruption. We will demonstrate that metabolic disorders could originate from endocrine disruption with a particular focus on convincing data from the literature. Eventually, we will present how handling an original mouse model of chronic exposition to a mixture of pollutants allowed demonstrating that a mixture of pollutants each at doses beyond their active dose could induce substantial deleterious effects on several metabolic end-points. This proof-of-concept study, as well as other studies on mixtures of pollutants, stresses the needs for revisiting the current threshold model used in risk assessment which does not take into account potential effects of mixtures containing pollutants at environmental doses, e.g., the real life exposure. Certainly, more studies are necessary to better determine the nature of the chemicals to which humans are exposed and at which level, and their health impact. As well, research studies on substitute products are essential to identify harmless molecules.