Phthalate is associated with insulin resistance in adipose tissue of male rat: role of antioxidant vitamins

Diethylhexyl phthalate exposure amplifies oxidant and inflammatory response in fetal hyperglycemia model predisposing insulin resistance in zebrafish embryos

Exposure of zebrafish embryos to glucose is a suitable model for the fetal hyperglycemia seen in gestational diabetes. Diethylhexyl phthalate (DEHP), which is considered an endocrine-disrupting chemical, is one of the most common phthalate derivatives used in stretching plastic and is encountered in every area where plastic is used in daily life. In the present study, the effects of DEHP on pathways related to insulin resistance and obesity were examined in zebrafish embryos exposed to glucose as a fetal hyperglycemia model. Zebrafish embryos were exposed to DEHP, glucose, and glucose + DEHP for 72 h post-fertilization (hpf), and developmental parameters and locomotor activities were monitored. At 72 hpf ins, lepa, pparγ, atf4a, and il-6 expressions were determined by RT-PCR. Glucose, lipid peroxidation (LPO), nitric oxide (NO) levels, glutathione S-transferase (GST), superoxide dismutase (SOD), and acetylcholine esterase (AChE) activities were measured spectrophotometrically. Compared with the control group, glucose, LPO, GST activity, il6, and atf4a expressions increased in all exposure groups, while body length, locomotor, and SOD activities decreased. While AChE activity decreased in the DEHP and glucose groups, it increased in the glucose + DEHP group. Although glucose exposure increased pparγ and lepa expressions, DEHP significantly decreased the expressions of pparγ and lepa both in the DEHP and glucose + DEHP groups. Our findings showed that DEHP amplified oxidant and inflammatory responses in this fetal hyperglycemia model, predisposing insulin resistance in zebrafish embryos.

Lactiplantibacillus plantarum RS20D Alleviates Male Reproductive Toxicity Induced by Pubertal Exposure to Di-n-butyl Phthalate and Mono-n-butyl Phthalate

Phthalate acid esters (PAEs) and their metabolites, such as di-n-butyl phthalate (DBP) and mono-n-butyl phthalate (MBP), are known to cause male reproductive damage. Lactiplantibacillus plantarum RS20D has demonstrated the ability to remove both DBP and MBP in vitro, suggesting its potential as a detoxifying agent against these compounds. This study aimed to investigate the protective effects of RS20D on DBP or MBP-induced male reproductive toxicity in adolescent rats. Oral administration of RS20D significantly mitigated the histological damage to the testes caused by MBP or DBP, restored sperm concentration, morphological abnormalities, and the proliferation index in MBP-exposed rats, and partially reversed spermatogenic damage in DBP-exposed rats. Furthermore, RS20D restored serum levels of estradiol (E2) and testosterone, and superoxide dismutase (SOD) activity in DBP-exposed rats, significantly increased testosterone levels in MBP-exposed rats, and restored copper (Cu) concentrations in the testes after exposure to DBP or MBP. Additionally, RS20D effectively modulated the intestinal microbiota in DBP-exposed rats and partially ameliorated dysbiosis induced by MBP, which may be associated with the alleviation of reproductive toxic effects induced by DBP or MBP. In conclusion, this study demonstrates that RS20D administration can alleviate male reproductive toxicity and gut dysbacteriosis induced by DBP or MBP exposure, providing a dietary strategy for the bioremediation of PAEs and their metabolites.

Addressing the challenges of combined sewer overflows

Europe's ageing wastewater system often combines domestic sewage with surface runoff and industrial wastewaters. To reduce the associated risk of overloading wastewater treatment works during storms, and to prevent wastewater backing-up into properties, Combined Sewer Overflows (CSOs) are designed into wastewater networks to release excess discharge into rivers or coastal waters without treatment. In view of growing regulatory scrutiny and increasing public concern about their excessive discharge frequencies and potential impacts on environments and people, there is a need to better understand these impacts to allow prioritisation of cost-effective solutions.We review: i) the chemical, physical and biological composition of CSOs discharges; ii) spatio-temporal variations in the quantity, quality and load of overflows spilling into receiving waters; iii) the potential impacts on people, ecosystems and economies. Despite investigations illustrating the discharge frequency of CSOs, data on spill composition and loading of pollutants are too few to reach representative conclusions, particularly for emerging contaminants. Studies appraising impacts are also scarce, especially in contexts where there are multiple stressors affecting receiving waters. Given the costs of addressing CSOs problems, but also the likely long-term gains (e.g. economic stimulation as well as improvements to biodiversity, ecosystem services, public health and wellbeing), we highlight here the need to bolster these evidence gaps. We also advocate no-regrets options to alleviate CSO problems taking into consideration economic costs, carbon neutrality, ecosystem benefit and community well-being. Besides pragmatic, risk-based investment by utilities and local authorities to modernise wastewater systems, these include i) more systemic thinking, linking policy makers, consumers, utilities and regulators, to shift from local CSO issues to integrated catchment solutions with the aim of reducing contributions to wastewater from surface drainage and water consumption; ii) broader societal responsibilities for CSOs, for example through improved regulation, behavioural changes in water consumption and disposal of waste into wastewater networks, and iii) greater cost-sharing of wastewater use.

Is Physical Activity an Efficient Strategy to Control the Adverse Effects of Persistent Organic Pollutants in the Context of Obesity? A Narrative Review

Obesity affects nearly 660 million adults worldwide and is known for its many comorbidities. Although the phenomenon of obesity is not fully understood, science regularly reveals new determinants of this pathology. Among them, persistent organic pollutants (POPs) have been recently highlighted. Mainly lipophilic, POPs are normally stored in adipose tissue and can lead to adverse metabolic effects when released into the bloodstream. The main objective of this narrative review is to discuss the different pathways by which physical activity may counteract POPs' adverse effects. The research that we carried out seems to indicate that physical activity could positively influence several pathways negatively influenced by POPs, such as insulin resistance, inflammation, lipid accumulation, adipogenesis, and gut microbiota dysbiosis, that are associated with the development of obesity. This review also indicates how, through the controlled mobilization of POPs, physical activity could be a valuable approach to reduce the concentration of POPs in the bloodstream. These findings suggest that physical activity should be used to counteract the adverse effects of POPs. However, future studies should accurately assess its impact in specific situations such as bariatric surgery, where weight loss promotes POPs' blood release.

Diethyl phthalate, a plasticizer, induces adipocyte inflammation and apoptosis in mice after long-term dietary administration

The incidence of metabolic diseases is increasing alarmingly in recent times. Parallel to nutritional excess and sedentary lifestyle, the random usage of several endocrine disrupting chemicals including plasticizers is reported to be closely associated with metabolic diseases. Diethyl phthalate (DEP) is a widely used plasticizer in a host of consumer and daily care products. Adipose tissue plays a central role in energy storage and whole-body metabolism. The impairment of adipose function is critically implicated in the pathogenesis of insulin resistance, diabetes, and related metabolic diseases. Recently, exposure to certain phthalate esters has been linked to the development of obesity and diabetes, although there are contradictions and the mechanisms are not clearly understood. In an effort to ascertain the metabolic consequences of chronic phthalate exposure and the underlying mechanism, the present study was designed to examine the effects of long-term dietary consumption of DEP in adipocytes. DEP-treated mice were hyperglycemic but nonobese; their body weight initially increased which subsequently was reduced compared to control. DEP exposure at lower levels impaired adipogenesis by downregulating the key transcription factor, peroxisome proliferator-activated receptor γ and its downstream insulin-sensitizing adipokine, adiponectin, thereby severely compromising adipocyte function. The activation of master regulator nuclear factor κB led to rise in proinflammatory cytokines. We found that DEP triggered intrinsic apoptotic pathways through activated cytochrome c-Apaf1-caspase 9-caspase 3 axis in adipocytes. Taken together, our data revealed that chronic administration of dietary DEP could unleash adverse metabolic outcomes by initiating oxidative stress, inflammation, and apoptosis in the adipocytes, thus leading to adipose tissue dysfunction.

Endoplasmic reticulum stress and pro-inflammatory responses induced by phthalate metabolites monoethylhexyl phthalate and monobutyl phthalate in 1.1B4 pancreatic beta cells

In recent years, phthalates and their metabolites have been associated with metabolic diseases such as diabetes mellitus. To investigate the effects of phthalate metabolites exposure on insulin production and release, 1.1B4 pancreatic beta cells were treated with different concentrations (0.001-1000 µM) of monoethylhexyl phthalate (MEHP) and monobutyl phthalate (MBP). For such purpose, the 1.1B4 cells were evaluated for their viability, apoptosis rate, lysosomal membrane permeabilization (LMP), mitochondrial membrane potential (ΔΨm), oxidative stress, ER stress status, in addition to their secretory functions. MEHP, not MBP, exhibited a notable reduction in metabolic viability, particularly at higher concentrations (500 and 1000 µM) following 24-hour exposure. Similarly, both MEHP and MBP induced decreased metabolic viability at high concentrations after 48- and 72-hour exposure. Notably, neither MEHP nor MBP demonstrated a significant impact on apoptosis rates after 24-hour exposure, and MBP induced mild necrosis at 1000 µM concentration. Cell proliferation rates, indicated by PCNA expression, decreased with 10 and 1000 µM MEHP and 0.1 and 10 µM MBP exposures. LMP analysis revealed an increase in 1000 µM MBP group. Exposure to 0.001 µM of both MEHP and MBP significantly reduced cellular glutathione (GSH) levels. No significant change in intracellular reactive oxygen species (ROS) levels and ΔΨm was observed, but MBP-exposed cells exhibited elevated levels of lipid peroxidation. Functional assessments of pancreatic beta cells unveiled reduced insulin secretion at low glucose concentrations following exposure to both MEHP and MBP, with concurrent alterations in the expression levels of key proteins associated with beta cell function, including GLUT1, GCK, PDX1, and MafA. Moreover, MEHP and MBP exposures were associated with alterations in ER stress-related pathways, including JNK, GADD153, and NF-κB expression, as well as PPARα and PPARγ levels. In conclusion, this study provides comprehensive insights into the diverse impacts of MEHP and MBP on 1.1B4 pancreatic beta cells, emphasizing their potential role in modulating cell survival, metabolic function, and stress response pathways.

Combined Astragalus, vitamin C, and vitamin E alleviate DEHP-induced oxidative stress and the decreased of insulin synthesis and secretion in INS-1 cells

Di-(2-ethylhexyl)-phthalate (DEHP), a common Phthalic acid ester (PAEs), has been reported to be associated with diabetes mellitus, yet the underlying mechanisms remain unknown. Combined nutrient interventions have been shown to alleviate the diabetic toxicity of DEHP. However, the effects and mechanisms of the combined intervention of Astragalus and vitamins (C and E) are currently unknown. In this study, we investigated the potential mechanisms of DEHP-induced diabetes mellitus through transcriptome analysis and vitro experiments using rat insulinoma cells (INS-1 cells). Furthermore, we explored the protection of the combined Astragalus, vitamin C, and vitamin E on DEHP-induced diabetes mellitus through these mechanisms. INS-1 cells in the logarithmic growth period were exposed to 125 umol/L DEHP followed by high-throughput sequencing analysis. The cell proliferation inhibition rate was determined using MTT assay for each group, and the cell apoptosis rate and intracellular ROS level were measured using flow cytometer. Finally, insulin levels and markers of oxidative stress were detected using ELISA kits in different groups. A total of 372 differentially expressed genes were found between the 125 umol/L DEHP and control groups, subsequent functional enrichment analyses indicated that DEHP induced oxidative stress and disturbed insulin levels. In INS-1 cells, the rate of cell proliferation inhibition, apoptosis, and the degree of oxidative stress increased concentration-dependently with increasing DEHP concentrations, while antioxidant intervention could reverse these changes. Insulin synthesis and secretion decreased after 240 μmol/L DEHP exposure stimulated by 25 mM glucose in INS-1 cells, also could antioxidant intervention alleviate these reductions. Based on these results, the underlying mechanism of DEHP impairing the function of INS-1 cells might be through apoptosis pathways induced by oxidative stress and direct reduction of insulin levels (both synthesis and secretion), while the optimal combination of Astragalus and vitamins (C and E) could exert an alleviating effect.

Endocrine disruptors in plastics alter β-cell physiology and increase the risk of diabetes mellitus

Plastic pollution breaks a planetary boundary threatening wildlife and humans through its physical and chemical effects. Of the latter, the release of endocrine disrupting chemicals (EDCs) has consequences on the prevalence of human diseases related to the endocrine system. Bisphenols (BPs) and phthalates are two groups of EDCs commonly found in plastics that migrate into the environment and make low-dose human exposure ubiquitous. Here we review epidemiological, animal, and cellular studies linking exposure to BPs and phthalates to altered glucose regulation, with emphasis on the role of pancreatic β-cells. Epidemiological studies indicate that exposure to BPs and phthalates is associated with diabetes mellitus. Studies in animal models indicate that treatment with doses within the range of human exposure decreases insulin sensitivity and glucose tolerance, induces dyslipidemia, and modifies functional β-cell mass and serum levels of insulin, leptin, and adiponectin. These studies reveal that disruption of β-cell physiology by EDCs plays a key role in impairing glucose homeostasis by altering the mechanisms used by β-cells to adapt to metabolic stress such as chronic nutrient excess. Studies at the cellular level demonstrate that BPs and phthalates modify the same biochemical pathways involved in adaptation to chronic excess fuel. These include changes in insulin biosynthesis and secretion, electrical activity, expression of key genes, and mitochondrial function. The data summarized here indicate that BPs and phthalates are important risk factors for diabetes mellitus and support a global effort to decrease plastic pollution and human exposure to EDCs.

Impact of Glyphosate on the Development of Insulin Resistance in Experimental Diabetic Rats: Role of NFκB Signalling Pathways

Glyphosate, an endocrine disruptor, has an adverse impact on human health through food and also has the potential to produce reactive oxygen species (ROS), which can lead to metabolic diseases. Glyphosate consumption from food has been shown to have a substantial part in insulin resistance, making it a severe concern to those with type 2 diabetes (T2DM). However, minimal evidence exists on how glyphosate impacts insulin-mediated glucose oxidation in the liver. Hence the current study was performed to explore the potential of glyphosate toxicity on insulin signaling in the liver of experimental animals. For 16 weeks, male albino Wistar rats were given 50 mg, 100 mg and 250 mg/kg b. wt. of glyphosate orally. In the current study, glyphosate exposure group was linked to a rise in fasting sugar and insulin as well as a drop in serum testosterone. At the same time, in a dose dependent fashion, glyphosate exposure showed alternations in glucose metabolic enzymes. Glyphosate exposure resulted in a raise in H₂O₂ formation, LPO and a reduction in antioxidant levels those results in impact on membrane integrity and insulin receptor efficacy in the liver. It also registered a reduced levels of mRNA and protein expression of insulin receptor (IR), glucose transporter-2 (GLUT2) with concomitant increase in the production of proinflammatory factors such as JNK, IKKβ, NFkB, IL-6, IL-1β, and TNF-α as well as transcriptional factors like SREBP1c and PPAR-γ leading to pro-inflammation and cirrhosis in the liver which results in the development of insulin resistance and type 2 diabetes. Our present findings for the first time providing an evidence that exposure of glyphosate develops insulin resistance and type 2 diabetes by aggravating NFkB signaling pathway in liver.

Endocrine adverse effects of mono(2-ethylhexyl) phthalate and monobutyl phthalate in male pubertal rats

Considering that research of adverse effects of mono(2-ethylhexyl) phthalate (MEHP) and monobutyl phthalate (MBP), two key metabolites of the most common phthalates used as plasticisers in various daily-life products, has been scattered and limited, the aim of our study was to provide a more comprehensive analysis by focusing on major organ systems, including blood, liver, kidney, and pancreas in 66 male pubertal rats randomised into eleven groups of six. The animals were receiving either metabolite at doses of 25, 50, 100, 200, or 400 mg/kg bw a day by gavage for 28 days. The control group was receiving corn oil. At the end of the experiment, blood samples were collected for biochemical, haematological, and immunological analyses. Samples of kidney, liver, and pancreas were dissected for histopathological analyses. Exposure to either compound resulted in increased liver and decreased pancreas weight, especially at the highest doses. Exposed rats had increased ALT, AST, glucose, and triglyceride levels and decreased total protein and albumin levels. Both compounds increased MCV and decreased haemoglobin levels compared to control. Although they also lowered the insulin level, exposed rats had negative islet cell and insulin antibodies, same as control. Treatment-related histopathological changes included sinusoidal degeneration in the liver, glomerular degeneration in the kidney, and degeneration of pancreatic islets. Our findings document toxic outcomes of MEHP and MBP on endocrine organs in male pubertal rats but also suggest the need for additional studies to better understand the mechanisms behind adverse effects in chronic exposure.

Phthalates - A family of plasticizers, their health risks, phytotoxic effects, and microbial bioaugmentation approaches

Phthalates are a family of reprotoxicant compounds, predominantly used as a plasticizer to improve the flexibility and longevity of consumable plastic goods. After their use these plastic products find their way to the waste disposal sites where they leach out the hazardous phthalates present within them, into the surrounding environment, contaminating soil, groundwater resources, and the nearby water bodies. Subsequently, phthalates move into the living system through the food chain and exhibit the well-known phenomenon of biological magnification. Phthalates as a primary pollutant have been classified as 1B reprotoxicants and teratogens by different government authorities and they have thus imposed restrictions on their use. Nevertheless, the release of these compounds in the environment is unabated. Bioremediation has been suggested as one of the ways of mitigating this menace, but studies regarding the field applications of phthalate utilizing microbes for this purpose are limited. Through this review, we endeavor to make a deeper understanding of the cause and concern of the problem and to find out a possible solution to it. The review critically emphasizes the various aspects of phthalates toxicity, including their chemical nature, human health risks, phytoaccumulation and entry into the food chain, microbial role in phthalate degradation processes, and future challenges.

Gestational and lactational exposure to the emergent alternative plasticizer 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) impairs lipid metabolism to a greater extent than the commonly used Di(2-ethylhexyl) phthalate (DEHP) in the adult rat mammary gland

Due to their endocrine disruption properties, phthalate plasticizers such as di(2-ethylhexyl) phthalate (DEHP) can affect the hormone-dependent development of the mammary gland. Over the past few years, DEHP has been partially replaced by 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) which also have potential endocrine disrupting properties. The goal of the present study is to understand the impact of a gestational and lactational exposure to DEHP and DINCH on mammary gland development using Sprague-Dawley rats. Both plasticizers altered the adipocytes of the mammary gland fat pad of adult progeny, as demonstrated by a decrease in their size, folding of their membrane and modulations of the lipid profiles. DEHP treatments decreased the expression of Rxrα and Scd1 at the low and high dose, respectively, but did not affect any of the other genes studied. DINCH modulation of lipid metabolism could be observed at puberty by a decreased expression of genes implicated in triglyceride synthesis, lipid transport and lipolysis, but by an increased expression of genes of the β-oxidation pathway and of genes involved in lipid storage and fatty acid synthesis at adulthood, compared to control and DEHP-treated rats. A strong upregulation of different inflammatory markers was observed following DINCH exposure only. Together, our results indicate that a gestational and lactational exposure to DINCH has earlier and more significant effects on lipid homeostasis, adipogenesis and the inflammatory state of the adult mammary gland than DEHP exposure. The long-term consequence of these effects on mammary gland health remained to be determined.

The crucial role of thioredoxin interacting protein in the liver insulin resistance induced by di (2-ethylhexyl) phthalates

The widespread usage of plastic products in human life has led to extensive exposure to plasticizers and resulted in serious health problems for humans, which has become a focus of toxicology research in the world. We aimed to explore the potential mechanism of liver insulin resistance induced by di(2-ethylhexyl) phthalate (DEHP) and working on a novel treatment to alleviate insulin resistance caused by excessive exposure to DEHP. For this purpose, in vivo and in vitro experiments were conducted, and the pivotal factors in the insulin signaling pathway were analyzed. In vivo study showed DEHP could lead to liver injury and insulin resistance. DEHP could break the balance of oxidative stress and cause accumulation of inflammatory factors. Genomics and proteomics experiment results revealed that DEHP could inhibit the mRNA and protein expression of insulin receptor, insulin receptor substrate, PI3K/Akt/mTOR, and glucose transporter 4. Nevertheless, the liver insulin resistance induced by DEHP could be reversed by Verapamil (thioredoxin interacting protein (TXNIP) inhibitor). Thus, we confirmed that DEHP caused insulin resistance by affecting the TXNIP in liver, further damaging the conduction of insulin signaling pathway. Therefore, adding Verapamil to the treatment of patients with insulin resistance due to plasticizers might be more effective.

Melatonin protects against nonylphenol caused pancreatic β-cells damage through MDM2-P53-P21 axis

Nonylphenol (NP) is an endocrine disrupting chemical, which widely exists in environment and can result in multiple system dysfunction. Pancreas as one of the most important organs is sensitive to NP, while the detail toxic effect is still less studied. Previously, we unveiled nonylphenol causes pancreatic damage in rats, herein, we further explore the potential mechanism and seek protection strategy in vitro. Insulinoma (INS-1) cells exposed to NP were observed to suffer oxidative stress and mitochondrial dysfunction, as reflected by the abnormal levels of reactive oxygen species, malonic dialdehyde, superoxide dismutase, Ca2+, and mitochondrial membrane potential. Melatonin (MT) was found to alleviate NP-induced mitochondrial dysfunction and oxidative stress, further inhibit apoptosis and restore pancreas function. Mechanically, MT induced the MDM2-P53-P21 signaling, which upregulated the Nrf2 signaling pathway. In summary, our study clarified NP-induced INS-1 cells mitochondrial dysfunction and oxidative stress, which could be ameliorated by MT through MDM2-P53-P21 axis.

The Role of Persistent Organic Pollutants in Obesity: A Review of Laboratory and Epidemiological Studies

Persistent organic pollutants (POPs) are considered as potential obesogens that may affect adipose tissue development and functioning, thus promoting obesity. However, various POPs may have different mechanisms of action. The objective of the present review is to discuss the key mechanisms linking exposure to POPs to adipose tissue dysfunction and obesity. Laboratory data clearly demonstrate that the mechanisms associated with the interference of exposure to POPs with obesity include: (a) dysregulation of adipogenesis regulators (PPARγ and C/EBPα); (b) affinity and binding to nuclear receptors; (c) epigenetic effects; and/or (d) proinflammatory activity. Although in vivo data are generally corroborative of the in vitro results, studies in living organisms have shown that the impact of POPs on adipogenesis is affected by biological factors such as sex, age, and period of exposure. Epidemiological data demonstrate a significant association between exposure to POPs and obesity and obesity-associated metabolic disturbances (e.g., type 2 diabetes mellitus and metabolic syndrome), although the existing data are considered insufficient. In conclusion, both laboratory and epidemiological data underline the significant role of POPs as environmental obesogens. However, further studies are required to better characterize both the mechanisms and the dose/concentration-response effects of exposure to POPs in the development of obesity and other metabolic diseases.

Endocrine-Disrupting Chemicals and Their Adverse Effects on the Endoplasmic Reticulum

There is growing concern regarding the health and safety issues of endocrine-disrupting chemicals (EDCs). Long-term exposure to EDCs has serious adverse health effects through both hormone-direct and hormone-indirect ways. Accordingly, some EDCs can be a pathogen and an inducer to the susceptibility of disease, even if they have a very low affinity on the estrogen receptor, or no estrogenic effect. Endoplasmic reticulum (ER) stress recently attracted attention in this research area. Because ER and ER stress could be key regulators of the EDC’s adverse effects, such as the malfunction of the organ, as well as the death, apoptosis, and proliferation of a cell. In this review, we focused on finding evidence which shows that EDCs could be a trigger for ER stress and provide specific examples of EDCs, which are known to cause ER stress currently.

Association Between Phthalate Exposure in Pregnancy and Gestational Diabetes: A Chinese Cross-Sectional Study

Objective

The present study aims to explore the association between phthalate exposure and the risk of gestational diabetes mellitus (GDM).

Materials and Methods

A total of 11 plasticizer metabolites were measured in patient morning urine using high-performance liquid chromatography. Furthermore, fasting blood glucose and fasting insulin were detected in first-trimester blood samples. The chemical concentration was described using the median, the metabolite concentration difference between the GDM and control groups was compared using the bootstrap method, and the correlations of the fasting blood glucose, fasting insulin, insulin resistance index, and phthalic acid ester (PAE) metabolites were analyzed using Spearman correlation analysis. The multivariate logistic regression model and predictive probability map were performed to help assess the linearity and nature of any dose–response relationship.

Results

Of the 224 women recruited for the present study, 200 met the inclusion criteria. Their measured outcomes and biomonitoring data were examined for the presence of chemicals. The results showed that the patients in the GDM group had higher mono-(2-ethylhexyl) phthalate (MEHP) and methylerythritol cyclophosphane concentrations in their bodies than the patients in the control group. Statistically significant MEHP–GDM associations were also observed (P < 0.001). The GDM and MEHP dose–response relationships were different among pregnant women aged <35 years and those aged >35 years (P < 0.001). Furthermore, gestational age >28 weeks exhibited similar changes to those aged ≤28 weeks (P = 0.059).

Conclusion

The findings of the present study add to the growing body of evidence supporting phthalate exposure as a GDM risk factor.

Dysregulation of autophagy acts as a pathogenic mechanism of non-alcoholic fatty liver disease (NAFLD) induced by common environmental pollutants

Non-alcoholic fatty liver disease (NAFLD) has been the most common chronic liver disease in the world, including the developing countries. NAFLD is metabolic disease with significant lipid deposition in the hepatocytes of the liver, which is usually associated with oxidative stress, inflammation and fibrogenesis, and insulin resistance. Progressive NAFLD can develop into non-alcoholic steatohepatitis (NASH) or hepatocellular carcinoma. The current evidence proposes that environmental pollutants promote development and progression of NAFLD, and autophagy plays a vital role but is multifactorial affected in NAFLD. In this review, we analyzed on the regulations of common environmental pollutants on autophagy in NAFLD. To clarify the involved roles of autophagy, we discussed the dysregulation of autophagy by environmental pollutants in adipose tissue and gut, and their interactions with liver, as well as epigenetic regulation on autophagy by environmental pollutants. Furthermore, protective roles of potential therapeutic treatments on the multiple-hits of autophagy in NAFLD were descripted.

Probiotic reduced the impact of phthalates and bisphenol A mixture on type 2 diabetes mellitus development: Merging bioinformatics with in vivo analysis

Linkage between bis(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and bisphenol A (BPA) co-exposure and type 2 diabetes mellitus (T2DM), as well as ability of multi-strained probiotic to reduce DEHP, DBP and BPA mixture-induced oxidative damage in rat pancreas were investigated. The Comparative Toxicogenomics Database, Cytoscape software and ToppGene Suite were used for data-mining. Animals were sorted into seven groups (n = 6): (1) Control group: corn oil, (2) P: probiotic: Saccharomyces boulardii + Lactobacillus rhamnosus + Lactobacillus plantarum LP 6595 + Lactobacillus plantarum HEAL9; (3) DEHP: 50 mg/kg b.w./day, (4) DBP: 50 mg/kg b.w./day, (5) BPA: 25 mg/kg b.w./day, and (6) MIX: 50 mg/kg b.w./day DEHP + 50 mg/kg b.w/day DBP + 25 mg/kg b.w./day BPA; (7) MIX + P. Rats were sacrificed after 28 days of oral exposure. In silico investigation highlighted 44 DEHP, DBP and BPA mutual genes linked to the T2DM, while apoptosis and oxidative stress were highlighted as the main mechanisms of DEHP, DBP and BPA mixture-linked T2DM. In vivo experiment confirmed the presence of significant changes in redox status parameters (TOS, SOD and SH groups) only in the MIX group, indicating possible additive effects, while probiotic ameliorated mixture-induced redox status changes in rat pancreatic tissue.

Mediation effects of thyroid function in the associations between phthalate exposure and glucose metabolism in adults

The mediating influence of thyroid function on the association of phthalate exposure with glucose metabolism, including insulin resistance, remains unclear. We explored the mediating influence of thyroid hormone levels on the phthalate exposure-insulin resistance association. This cross-sectional study of 217 Taiwanese adults assessed insulin resistance (Homeostatic Model Assessment for Insulin Resistance, HOMA-IR scores) and the levels of 11 urinary phthalate metabolites and 5 thyroid hormones. Multiple regression models were used to analyze the associations among serum thyroid hormone levels, urinary phthalate metabolite levels, and HOMA-IR scores. The mediation analysis assessed the influence of thyroid function on the phthalate exposure-HOMA-IR association. Our data indicated urinary mono-ethylhexyl phthalate (MEHP) levels was negatively associated with free thyroxine (T₄) (β = -0.018; 95% confidence interval [CI]: -0.031, -0.005) and positively associated with HOMA-IR scores (β = 0.051, 95% CI: 0.012, 0.090). The study also revealed urinary mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) levels was negatively associated with free T₄ (β = -0.036, 95% CI: -0.056, -0.017) and HOMA-IR (β = 0.070, 95% CI: 0.013, 0.126). Free T₄ and HOMA-IR had a negative association (β = -0.757, 95% CI: -1.122, -0.392). In the mediation analysis, free T₄ mediated 24% and 35% of the associations of urinary MEHP and MEOHP with HOMA-IR, respectively. Our findings revealed the mediating role of thyroid function in the phthalate exposure-glucose metabolism association in adults.

Typical phthalic acid esters induce apoptosis by regulating the PI3K/Akt/Bcl-2 signaling pathway in rat insulinoma cells

Di-(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) are representative phthalic acid esters (PAEs), a class of environmental endocrine disruptors used as plasticizers. PAEs exposure is associated with glucose metabolism, insulin resistance, and glucose tolerance; however, the mechanism and various PAE effects on human glucose metabolism remain largely unknown. In this study, we investigated the effects of DEHP, DBP, and their mixture on rat insulinoma (INS-1) cell apoptosis and the mechanism involved in vitro. The INS-1 cells were cultured in RPMI-1640 + 10% fetal bovine serum for 24 h and pretreated with dimethyl sulfoxide (vehicle, <0.1%), DEHP (30 μM), DBP (30 μM), and their mixture (30 μM DEHP + 30 μM DBP). The methyl-thiazolyl tetrazolium bromide test was used to measure cell viability. Hoechst 33342/propidium iodide (PI) staining and Annexin V-FITC/PI staining, 2',7'-dichlorofluorescein diacetate assay, and glucose-induced insulin secretion assay were used to detect cell apoptosis rates, intracellular reactive oxygen species (ROS), and insulin secretion in INS-1, respectively. The mRNA expression levels of Bcl-2, Bax, Caspase 9, Caspase 8, Caspase 3, phosphoinositide 3-kinase (PI3K), and Akt were detected using real-time quantitative reverse transcription PCR; their protein expression levels were detected using western blotting. To the best of our knowledge, this study was the first to show that the combined effect of the two PAEs promotes a ROS-mediated PI3K/Akt/Bcl-2 pathway-induced pancreatic β cell apoptosis that is significantly higher than the effects of each PAE. Thus, safety standards and studies do not consider this effect as a significant oversight when blending PAEs. We assert that this must be addressed and corrected for establishing more impactful and safer standards.

The implication of mitochondrial dysfunction and mitochondrial oxidative damage in di (2-ethylhexyl) phthalate induced nephrotoxicity in both in vivo and in vitro models

Di-(2-ethylhexyl) phthalate (DEHP) and its main metabolite, monoethylhexyl phthalic acid (MEHP), are a serious threat to human and animals' health in the current century. However, their exact mechanism to induce nephrotoxicity is not clear. In the current study, we addressed toxic effects of MEHP and DEHP on embryonic human kidney cells (HEK-293 cell line) and kidney tissue of rats, respectively. In the HEK-293, MTT assay and oxidative stress parameters were measured after treatment with different concentrations of MEHP. For in vivo study, rats were treated with different doses of DEHP (50, 100, 200, 400 mg/kg) via gavage administration for 45 days. The renal function biomarkers (BUN and creatinine) were determined in serum of rats. Mitochondrial toxic parameters including MTT, mitochondrial membrane potential (MMP), mitochondrial swelling, and also oxidative stress parameters were measured in isolated kidney mitochondria. Histopathological effects of DEHP were also evaluated in rats' kidneys. We demonstrated that MEHP induced oxidative stress and cytotoxicity in HEK-293 cells in a concentration dependent manner. The administration of DEHP led to histopathological changes in kidney tissue, which concurred with BUN and creatinine alternations in serum of rats. The results of present study showed a significant mitochondrial dysfunction and oxidative stress confirmed by enhancement of mitochondrial swelling, mitochondrial reactive oxygen species (ROS) and malondialdehyde (MDA), and reduction of MMP and mitochondrial glutathione (GSH). Taken together, this study showed that DEHP/MEHP resulted in mitochondrial dysfunction and oxidative damage, which suggest a vital role of mitochondria in DEHP/MEHP-induced nephrotoxicity.

Long-term dietary administration of diethyl phthalate triggers loss of insulin sensitivity in two key insulin target tissues of mice

Over the past years, a growing body of work has linked numerous pervasive environmental chemicals with a multitude of adverse reproductive, developmental, behavioral, and metabolic changes in humans and animal models. Plasticizers include a wide variety of phthalate esters that are extensively used in a host of personal day care and cosmetic products. Many population-based studies have indicated a close association between diethyl phthalate (DEP) and diabetes albeit the mechanisms remain much unexplored. Presently, we report that long-term dietary administration of DEP to adult male Swiss albino mice at two different concentrations mirroring the recommended tolerable doses, severely impaired insulin signaling in hepatocytes and adipocytes. This was concomitant with sustained oxidative stress from the overactivation of NADPH oxidase 2, a major intracellular source of reactive oxygen species, in both the cell types. The present study provides evidences of the onset of insulin resistance in mice after chronic exposure to DEP in diet even at lower levels. This, in turn, can have serious pathological consequences with ultimate manifestations of type 2 diabetes and metabolic syndrome (MetS). Thus, by disrupting the central metabolic function of liver and adipose tissue, the key insulin target tissues, daily exposure to phthalates in plastics can potentially contribute to the alarming prevalence of MetS in recent times.

Toxic Effects of the Mixture of Phthalates and Bisphenol A-Subacute Oral Toxicity Study in Wistar Rats

Phthalates and bisphenol A, classified as endocrine disruptors, have weak estrogenic, anti-androgenic properties, and affect thyroid hormone regulation. The aim of this study on male rats was to compare the subacute toxic effects of low doses of single compounds (bis (2 -ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and bisphenol A (BPA)) with the effects of their mixture through different biochemical, hormonal, and hematological parameters. Rats were divided into five experimental groups: Control (corn oil), DEHP (50 mg/kg b.w./day), DBP (50 mg/kg b.w./day), BPA (25 mg/kg b.w./day), and MIX (50 mg/kg b.w./day DEHP + 50 mg/kg b.w/day DBP + 25 mg/kg b.w./day BPA). Animals were sacrificed after 28 days of oral treatment and blood was collected for further analysis. The results demonstrated that the mixture produced significant changes in lipid profile, liver-related biochemical parameters, and glucose level. Furthermore, the opposite effects of single substances on the thyroxine level have been shown in comparison with the mixture, as well as a more pronounced effect of the mixture on testosterone level. This study contributes to the body of knowledge on the toxicology of mixtures and gives one more evidence of the paramount importance of mixture toxicity studies, especially in assessing the endocrine disruptive effects of chemicals.

Antidiabetic Activity of Gold Nanoparticles Synthesized Using Wedelolactone in RIN-5F Cell Line

We synthesized the gold nanoparticles (AuNPs) using wedelolactone (WDL) and characterized them using UV-visible spectroscopy, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopic (SEM), transmission electron microscopic (TEM), energy dispersive X-ray diffraction, and atomic force microscopic (AFM) studies. The electronic spectrum exhibited an absorption peak at 535 nm. The FT-IR results proved that WDL was stabilized on the surface of AuNPs by acting as a capping or reducing agent. The crystalline structure was affirmed by XRD pattern and the spherical shape of WDL-AuNPs was evidenced by SEM, TEM, and AFM. The synthesized WDL-AuNPS were evaluated for anti-diabetic activity in pancreatic RIN-5F cell lines. In vitro results showed that WDL-AuNPs did not only improve the insulin secretion affected by di-(2-ethylhexyl) phthalate (DEHP), but also the cell viability in RIN5F cells. WDL-AuNPs treatment modulates the pro-apoptotic proteins and anti-apoptotic proteins expression to prevent the cells undergoing apoptosis in DEHP-exposed RIN-5F cells. The exposure of DEHP causes an increase in ROS production and lipid peroxidation levels. The free radical scavenging and antioxidant properties of WDL-AuNPs increase the deleterious effect caused by DEHP. On the other side, WDL-AuNPs increase mRNA expressions of insulin-signaling proteins in RIN-5F cells. This study concludes that WDL-AuNPs can be successfully used to regulate the expression of Bcl-2 family proteins, reduce lipid peroxidation, and to improve the secretion of antioxidants and insulin through the GLUT2 pathway in RIN-5F cell lines.

Serum beta-carotene modifies the association between phthalate mixtures and insulin resistance: The National Health and Nutrition Examination Survey 2003-2006

Animal models suggest a protective role of antioxidants against the adverse effect of di-2-ethylhexyl phthalate (DEHP) on insulin resistance. However, no epidemiologic study has examined the effects observed in the animal model. We conduct a study to examine associations of urinary concentrations of phthalate metabolites (individually and as a mixture) with insulin resistance, along with potential effect modification by serum antioxidant concentrations. This cross-sectional study included 1605 participants (51% males) aged 12-85 from the National Health and Nutrition Examination Surveys (2003-2006). Urinary concentrations of 9 phthalate metabolites were measured from spot urine samples. Antioxidant (vitamin A, C, E, and carotenoids) concentrations were measured from a fasting serum sample. We used Bayesian Kernel Machine Regression (BKMR) to evaluate associations between phthalate metabolite mixtures and insulin resistance, and examined whether serum antioxidant levels modified these associations, while accounting for the correlations of multiple concurrent exposures. A change in urinary ΣDEHP concentrations from the 25th to the 75th percentile was associated with a higher log HOMA-IR of 0.07 (95% CI = 0.01, 0.14) (4.85% increase in HOMA-IR). In contrast, the same change in urinary monoethyl phthalate (MEP) was associated with a lower HOMA-IR of -0.07 (95% CI = -0.14, -0.02) (6.68% decrease in HOMA-IR). The positive association between ΣDEHP and HOMA-IR became weaker at higher concentrations of serum β-carotene. The relationship between MEP and HOMA-IR, however, was not modified by the serum antioxidants examined. The remaining phthalate metabolites were unrelated to HOMA-IR. In this cross-sectional study, the positive association between DEHP exposure and insulin resistance weakened among participants with higher concentrations of serum β-carotene. As this is the first human report on the protective role of serum β-carotene on DEHP induced insulin resistance, future studies are needed.

Environmental neglect: endocrine disruptors as underappreciated but potentially modifiable diabetes risk factors

Type 2 diabetes prevalence is increasing dramatically across the globe, imposing a tremendous toll on individuals and healthcare systems. Reversing these trends requires comprehensive approaches to address both classical and emerging diabetes risk factors. Recently, environmental toxicants acting as endocrine-disrupting chemicals (EDCs) have emerged as novel metabolic disease risk factors. EDCs implicated in diabetes pathogenesis include various inorganic and organic molecules of both natural and synthetic origin, including arsenic, bisphenol A, phthalates, polychlorinated biphenyls and organochlorine pesticides. Indeed, evidence implicates EDC exposures across the lifespan in metabolic dysfunction; moreover, specific developmental windows exhibit enhanced sensitivity to EDC-induced metabolic disruption, with potential impacts across generations. Importantly, differential exposures to diabetogenic EDCs likely also contribute to racial/ethnic and economic disparities. Despite these emerging links, clinical practice guidelines fail to address this underappreciated diabetes risk factor. Comprehensive approaches to stem the tide of diabetes must include efforts to address its environmental drivers.

Association between phthalate exposure and glycosylated hemoglobin, fasting glucose, and type 2 diabetes mellitus: A case-control study in China

Epidemiological studies have shown that exposure to phthalates (PAEs) is associated with type 2 diabetes mellitus (T2DM) and related markers, but limited evidence has been found in Chinese people. Given that China has the highest number of people with DM and Chinese people show relatively higher exposure levels of PAEs, a case-control study was conducted in China to explore the associations of PAE exposure with T2DM and two glycemic indicators, including fasting glucose and glycosylated hemoglobin (HbA1c). Two hundred fifty people with T2DM and 250 controls were recruited in this study. Multivariable logistic regression analyses showed significant positive associations between urinary concentrations of most studied PAE metabolites (mPAEs) and T2DM, with odd ratios comparing extreme mPAEs quartiles ranging from 2.09 to 40.53, whereas two secondary metabolites, mono (2-ethyl-5-carboxypentyl) phthalate and mono [(2-carboxymethyl) hexyl] phthalate showed significant inverse relationships with T2DM. In addition, multivariable linear regression analyses showed that urinary concentrations of mono (2-ethyl-5-hydroxyhexyl) phthalate were positively associated with HbA1c levels in controls (β = 0.013; 95% CI: 0.003, 0.023). A significant positive association was also observed for urinary mono (2-ethylhexyl) phthalate and fasting glucose (β = 0.009; 95% CI: 0.002, 0.016). In the stratified analyses, the significant associations of mPAEs with T2DM were more likely to be observed in the younger people, compared to the older people. The significant positive associations between urinary mPAEs and HbA1c levels were more likely to be found in the lower body mass index (BMI) subgroup. Additionally, urinary specific mPAEs were found to be significantly positively related to fasting glucose in males and the older people. The findings suggest that exposure to PAEs is associated with T2DM, fasting glucose, and HbA1c levels in Chinese people and the associations of exposure to PAEs with T2DM, fasting glucose, and HbA1c may differ between sexes, BMIs, or ages.

Effects of citrate ester plasticizers and bis (2-ethylhexyl) phthalate in the OECD 28-day repeated-dose toxicity test (OECD TG 407)

Citrate esters are considered functional alternatives to phthalate plasticizers, but their toxicity remains poorly understood. The toxicity of citrate esters, including triethyl 2-acetylcitrate (ATEC) and trihexyl O-acetylcitrate (ATHC), were examined together with that of bis (2-ethylhexyl) phthalate (DEHP) using the Organization for Economic Co-operation and Development Test Guideline 407 (OECD TG407). Following 28-day oral administration, no significant differences in body weight or the weight of the brain, pituitary, heart, epididymis, seminal vesicles, or coagulating gland were found between the vehicle control and DEHP, ATEC or ATHC groups. In the 400 mg/kg day DEHP group, liver, adrenal, thymus, spleen, kidney, testis, and prostate weights were significantly increased. In the 400 mg/kg day ATHC group, kidney, adrenal, thymus, testis and prostate weights were significantly increased. In the 400 mg/kg day ATEC group, kidney, adrenal and testis weights were significantly increased. Hepatocyte size was significantly increased in the 400 mg/kg day DEHP group, suggestive of hepatotoxicity, but was not increased in the ATEC or ATHC groups. There were no significant differences in white blood cell, red blood cell or platelet counts, hemoglobin concentrations, hematocrit, mean corpuscular volume, fasting glucose, insulin, or testosterone concentrations between the vehicle control and DEHP, ATEC and ATHC groups. In the ATHC 400 mg/kg day group, T3 was decreased while T4 was increased, suggestive of disruption of thyroid function. The results of the OECD TG407 subacute repeated dosing toxicity test indicate ATEC is less toxic compared to ATHC or DEHP and could be recommended as an alternative to phthalate plasticizers.

Maternal urinary phthalate metabolites in relation to gestational diabetes and glucose intolerance during pregnancy

BACKGROUND

Phthalates are common plasticizer chemicals that have been linked to glucose intolerance in the general population, but there is only limited research on their association with gestational diabetes (GDM).

OBJECTIVE

We evaluated the association between 11 urinary phthalate metabolites and GDM, impaired glucose tolerance (IGT), and continuous blood glucose concentration during pregnancy in The Infant Development and Environment Study (TIDES). Based on prior study results, our primary analyses focused on monoethyl phthalate (MEP) in relation to our outcomes of interest.

STUDY DESIGN

We used multi-variable logistic regression to examine the odds of GDM and IGT in relation to an interquartile-range (IQR) increase in natural log (ln)-transformed, specific gravity (SG)-adjusted first trimester (T1) and average of T1 and third trimester (T3) ("T1T3avg") phthalate metabolite concentrations. We fit linear regression models to examine the percent change in blood glucose per IQR increase in ln-transformed, SG-adjusted T1 and T1T3avg phthalates. In sensitivity analyses, we examined interactions between exposure and race. We adjusted for maternal age, maternal body mass index, study center, race/ethnicity, parity, and gestational age at glucose testing.

RESULTS

In our sample of 705 pregnant women, we observed 60 cases of GDM, 90 cases of IGT, and an average GLT blood glucose of 113.6 ± 27.7 mg/dL. In our primary analysis, T1T3avg MEP was positively associated with GDM ([OR (95% CI) per IQR increase] T1T3avg MEP: 1.61 (1.10, 2.36)). In secondary analyses, most other phthalates were not found to be related to study outcomes, though some associations were noted. Sensitivity analyses indicated possible strong race-specific associations in Asians, though these results are based on a small sample size (n = 35).

CONCLUSION

In alignment with our a priori selection, we documented an association between T1T3avg MEP and GDM. Additional phthalate metabolites were also found to be linked to glucose intolerance, with possible stronger associations in certain racial/ethnic subgroups. Given the prevalence of phthalate exposures and the growing evidence of associations with metabolic outcomes, future studies should continue to examine this question in diverse cohorts of pregnant women, particularly in those who may be at higher risk for GDM and IGT.

Maternal di-(2-ethylhexyl) phthalate exposure alters hepatic insulin signal transduction and glucoregulatory events in rat F1 male offspring

Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer with endocrine disrupting properties. Its widespread use resulted in constant human exposure including fetal development and postnatal life. Epidemiological and experimental data have shown that DEHP has a negative influence on glucose homeostasis. However, the evidence regarding the effect of maternal DEHP exposure on hepatic glucose homeostasis is scarce. Hence, we investigated whether DEHP exposure during gestation and lactation disrupts glucose homeostasis in the rat F₁ male offspring at adulthood. Pregnant rats were divided into three groups and administered with DEHP (10 and 100 mg/kg/day) or olive oil from gestational day 9 to postnatal day 21 (lactation period) through oral gavage. DEHP-exposed offspring exhibited hyperglycemia, impaired glucose and insulin tolerances along with hyperinsulinemia at postnatal day 80. DEHP exposure significantly reduced the levels of insulin signaling molecules such as insulin receptors, IRS1, Akt and its phosphorylated forms. GSK3β and FoxO1 proteins increased in DEHP-exposed groups whereas its phosphorylated forms decreased. Treated groups showed decreased glycogen synthase activity and glycogen concentration. Glucose-6-phosphatase and phosphoenolpyruvate carboxykinase mRNA level and enzyme activity increased in DEHP-treated groups. The interaction between FoxO1-glucose-6-phosphatase and FoxO1-phosphoenolpyruvate carboxykinase was also increased. This study suggests that DEHP exposure impairs insulin signal transduction and alters glucoregulatory events leading to the development of type 2 diabetes in F₁ male offspring.

Impairment of bisphenol F on the glucose metabolism of zebrafish larvae

Bisphenol F (BPF) is a substitute of bisphenol A in the production of epoxy resin and polycarbonate. Its extensive use in consumer products leads to a wide human exposure at high levels. Although the adverse effects of BPF on animal health are of increasing public concern, its risks on systematic glucose metabolism and blood glucose concentrations still remain largely unknown. Using zebrafish larvae as the model animal, we investigated the disturbance of BPF exposure on glucose metabolism and the underlying mechanisms. Zebrafish larvae at 96 h post fertilization were exposed to 0.1, 1, 10, and 100 μg/L of BPF for 48 h. Compared with the control group, glucose levels of larvae increased significantly in the 10 and 100 μg/L exposure groups, which are associated with enhancement of gluconeogenesis and suppression of glycolysis induced by high doses of BPF. Additionally, both mRNA expressions and protein levels of insulin increased significantly in the 10 and 100 μg/L exposure groups, while transcription levels of genes encoding insulin receptor substrates decreased significantly in these groups, indicating a possibly decreased insulin sensitivity due to impairment of insulin signaling transduction downstream of insulin receptor. Further, compared with BPF alone, co-exposure of larvae to BPF and rosiglitazone, an insulin sensitizer, significantly attenuates increases in both glucose levels and mRNA expressions of a key gluconeogenesis enzyme. Our data therefore indicate impairing insulin signaling transduction may be the main mechanism through which BPF disrupts glucose metabolism and induces hyperglycemia. Results of the present study inform the health risk assessment of BPF and also suggest the use of zebrafish larvae in large-scale screening of chemicals with possible glucose metabolism disturbing effect.

Postnatal exposure to di-(2-ethylhexyl)phthalate alters cardiac insulin signaling molecules and GLUT4Ser488 phosphorylation in male rat offspring

Di-(2-ethylhexyl)phthalate (DEHP), a distinctive endocrine-disrupting chemical, is widely used as a plasticizer in a variety of consumer products. It can easily cross the placenta and enter breast milk and then it is rapidly absorbed by offspring. Since it is generally accepted that individuals are more sensitive to chemical exposure during vital developmental periods, we investigated whether DEHP exposure during lactation affects cardiac insulin signaling and glucose homeostasis in the F₁ male rat offspring at postnatal day 22 (PND22). Lactating Wistar rats were administered with DEHP (1, 10, and 100 mg/kg/d) or olive oil from lactation day 1 to 21 by oral gavage. All the male pups were perfused and killed on PND22. On the day before the killing, they were kept for fasting overnight and blood was collected. The cardiac muscle was dissected out, washed in ice-cold physiological saline repeatedly and used for the assay of various parameters. DEHP-exposed offspring had significantly lower body weight than the control. DEHP-exposed offspring showed elevated blood glucose, decreased ¹⁴ C-2-deoxyglucose uptake and ¹⁴ C-glucose oxidation in cardiac muscle at PND22. The concentration of upstream insulin signaling molecules such as insulin receptor subunit β (InsRβ) and insulin receptor substrate 1 (IRS1) were downregulated in DEHP-exposed offspring. However, no significant alterations were observed in protein kinase B (Akt) and Akt substrate of 160 kDa (AS160). Surprisingly, phosphorylation of IRS1 ^Tyr632 and Akt ^Ser473 were diminished. Low levels of glucose transporter type 4 (GLUT4) protein and increased GLUT4 ^Ser488 phosphorylation which decreases its intrinsic activity and translocation towards plasma membrane were also recorded. Lactational DEHP exposure predisposes F ₁ male offspring to cardiac glucometabolic disorders at PND22, which may impair cardiac function.

Di-(2-ethylhexyl)-phthalate induces glucose metabolic disorder in adolescent rats

As a plasticizer, di-(2-ethylhexyl)-phthalate (DEHP) is widely added in various commercial products. Some researchers had suggested that DEHP has adverse effects on the glucose metabolism, but the mechanisms remain unclear. Adolescent Wistar rats were divided into four groups and administered DEHP by gavage at 0, 5, 50, and 500 mg kg^-1 d^-1 for 28 days. ELISA was used to quantify the serum insulin and leptin levels; RT-PCR, immunohistochemistry, and Western blot were used to detect the mRNA and protein expressions of Janus-activated kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), suppressor of cytokine signaling 3 (SOCS3), leptin receptor (Ob-R), and insulin receptor (IR) in liver and pancreas In comparison to the control group, the DEHP-treated rats showed the following: (1) higher organ coefficient of liver; (2) higher fasting blood glucose levels, higher fasting serum insulin and leptin levels, higher insulin resistance index homeostasis model assessment; (3) lower protein levels of Ob-R and IR in the liver and pancreas; (4) higher protein levels of JAK2 and STAT3 in the liver; and (5) higher protein and mRNA levels of SOCS3 in the liver and pancreas. Exposure to DEHP induced glucose metabolic disorder in the adolescent rats, and the mechanism is that DEHP may interfere with the JAK2/STAT3/SOCS3 pathway, regulated the sensitivity of the insulin receptor and leptin receptor.

Inhibitor of Differentiation-3 and Estrogenic Endocrine Disruptors: Implications for Susceptibility to Obesity and Metabolic Disorders

The rising global incidence of obesity cannot be fully explained within the context of traditional risk factors such as an unhealthy diet, physical inactivity, aging, or genetics. Adipose tissue is an endocrine as well as a metabolic organ that may be susceptible to disruption by environmental estrogenic chemicals. Since some of the endocrine disruptors are lipophilic chemicals with long half-lives, they tend to bioaccumulate in the adipose tissue of exposed populations. Elevated exposure to these chemicals may predispose susceptible individuals to weight gain by increasing the number and size of fat cells. Genetic studies have demonstrated that the transcriptional regulator inhibitor of differentiation-3 (ID3) promotes high fat diet-induced obesity in vivo. We have shown previously that PCB153 and natural estrogen 17β-estradiol increase ID3 expression. Based on our findings, we postulate that ID3 is a molecular target of estrogenic endocrine disruptors (EEDs) in the adipose tissue and a better understanding of this relationship may help to explain how EEDs can lead to the transcriptional programming of deviant fat cells. This review will discuss the current understanding of ID3 in excess fat accumulation and the potential for EEDs to influence susceptibility to obesity or metabolic disorders via ID3 signaling.

Exposure to phthalates in patients with diabetes and its association with oxidative stress, adiponectin, and inflammatory cytokines

Epidemiologic studies have revealed higher concentrations of the metabolites of phthalic acid esters (mPAEs) in patients with type 2 diabetes. On the other hand, oxidative stress, adiponectin, and inflammatory cytokines play important roles in the pathogenesis of diabetes and its complications. However, little information is known about the association between exposure to PAEs and these physiological parameters. Hence, paired urine and blood samples were collected from a total of 329 volunteers, and 11 main mPAEs and malondialdehyde (MDA), as a biomarker of oxidative stress, were measured in the urine samples. Serum adiponectin and tumor necrosis factor-α (TNF-α), a biomarker of inflammation, were also measured. Multivariable linear regression was used to assess the association between urinary mPAEs and these physiological parameters in the total subjects and subjects stratified by age, sex, and body mass index (BMI) to elucidate their possible interactions. All 11 mPAEs were detected in the urine with detection rates of 42.9%-100% and geometric means of 0.30-54.52ng/mL (0.44-79.93μg/g creatinine). The mPAEs were all positively associated with MDA levels. There were significant positive associations between monomethyl phthalate (mMP) and TNF-α, and inverse associations between mMP and adiponectin levels. In the stratified analysis, there were age-, sex-, and BMI-specific differences for these associations. The positive associations between mPAEs and MDA were insignificant in some subgroups, especially in the larger age group. However, in the larger BMI group, summed metabolites of di-(2-ethylhexyl) phthalate (∑DEHP) and mono(2-ethylhexyl) phthalate were positively associated with TNF-α, and the concentrations of ∑DEHP were negatively associated with adiponectin. Our findings suggested that PAE exposure is associated with oxidative stress, adiponectin, and inflammatory cytokines in diabetic patients; further studies on toxicology and a comparison with general population are needed.

Polluted Pathways: Mechanisms of Metabolic Disruption by Endocrine Disrupting Chemicals

PURPOSE OF REVIEW

Environmental toxicants are increasingly implicated in the global decline in metabolic health. Focusing on diabetes, herein, the molecular and cellular mechanisms by which metabolism disrupting chemicals (MDCs) impair energy homeostasis are discussed.

RECENT FINDINGS

Emerging data implicate MDC perturbations in a variety of pathways as contributors to metabolic disease pathogenesis, with effects in diverse tissues regulating fuel utilization. Potentiation of traditional metabolic risk factors, such as caloric excess, and emerging threats to metabolism, such as disruptions in circadian rhythms, are important areas of current and future MDC research. Increasing evidence also implicates deleterious effects of MDCs on metabolic programming that occur during vulnerable developmental windows, such as in utero and early post-natal life as well as pregnancy. Recent insights into the mechanisms by which MDCs alter energy homeostasis will advance the field's ability to predict interactions with classical metabolic disease risk factors and empower studies utilizing targeted therapeutics to treat MDC-mediated diabetes.

Association between urinary phthalates and metabolic abnormalities in obese Thai children and adolescents

BACKGROUND

Several endocrine disruptors (including phthalates) are considered to be a cause of obesity. However, the current evidence has not conclusively established an association between phthalates and metabolic abnormalities, especially in children. The objective of the study was to evaluate the association between urinary phthalate metabolites and metabolic abnormalities in obese Thai children and adolescents.

METHODS

This cross-sectional case-control study was conducted in participants aged 7-18 years and divided into two groups: normal weight and overweight/obesity. Spot urine concentrations of two phthalate metabolites (monomethyl phthalate [MMP] and mono-n-buthyl phthalate [MBP]) were measured by high performance liquid chromatography (HPLC). Anthropometric data, including weight, height, body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHTR), were measured and calculated. Fasting plasma glucose, insulin, HbA1c, lipid profiles and hepatic transaminase were analyzed, and insulin resistance indices were calculated.

RESULTS

One hundred and fifty-five participants were included. The median MMP level in the normal weight and the overweight/obesity groups were 0 (0, 459.83) and 0 (0, 1623.50) μg/g Cr, respectively (p=0.933). The median MBP level in the normal weight and the overweight/obesity groups were 233.6 (118.1, 633.62) and 206.94 (7.4, 427.7) μg/g Cr, respectively (p=0.083). After adjusting for age, gender and puberty, there was no correlation between MBP and all anthropometric data and metabolic profiles. Participants with hypertriglyceridemia had lower MBP levels than those with normal TG level. MMP levels were not significantly different between the participants with normal and abnormal weight of all metabolic parameters.

CONCLUSIONS

Participants with hypertriglyceridemia had lower MBP levels than those with normotriglyceridemia. However, it cannot show the correlation between phthalate and metabolic parameters.

Mono-2-ethylhexyl phthalate associated with insulin resistance and lower testosterone levels in a young population

Phthalates are commonly used as plasticizers and are reported to associate with testicular dysfunction or insulin resistance in different studies, but the concurrent relationship between phthalate exposure, testosterone levels, and insulin resistance in the young population is not well understood. We recruited 786 subjects aged 12-30 years from a population-based sample of Taiwanese adolescents and young adults from 2006 to 2008. Generalized additive models were used to evaluate glucose homeostasis and testicular function in relation to seven urinary phthalate metabolites among adolescents (aged 12-20) and young adults (aged 20-30) in Taiwan. We observed a trend toward a decrease in male testosterone and an increase in urinary mono-2-ethylhexyl phthalate (MEHP) levels across four quartiles of homeostasis model assessment of insulin resistance (HOMA-IR). After adjusting for potential covariates, generalized additive models further showed that log-transformed insulin and HOMA-IR were raised by 0.055 [95% confidence interval (CI), 0.027-0.082] and 0.056 (95% CI, 0.027-0.084), respectively, with a one-unit increase in log-transformed MEHP in young adults. In male adults (aged 22-30), the log-testosterone levels were reduced by 0.018 (95% CI, 0.001-0.036), with a one-unit of increase in log-transformed MEHP. Such relationships were not observed in adolescents. In conclusion, this study demonstrated age-related associations of urinary MEHP metabolites with impaired metabolic homeostasis of glucose that were only observed in young adults. In addition, MEHP exposure was concurrently associated with lower testosterone levels in young, male adults.

Exposure to bisphenols and phthalates and association with oxidant stress, insulin resistance, and endothelial dysfunction in children

BACKGROUND

The health effects of bisphenol A (BPA) and di-(2-ethylhexyl) phthalate (DEHP) have been studied extensively in children. The impact of other chemicals in these two classes has not been investigated as fully.

METHODS

We conducted a cross-sectional pilot study of 10-13 y old healthy children. We assessed descriptive, univariable, and multivariable associations of urinary metabolites of bisphenols and phthalates with oxidant stress, insulin resistance, body mass, and endothelial dysfunction. Possible associations with brachial artery distensibility, pulse wave velocity (markers of vascular stiffness), and serum endothelial cell-derived microparticle levels were also assessed.

RESULTS

We enrolled 41 participants, 12.1 ± 1.0 y, most of whom were Mexican Americans (42%) or other Hispanics (34%). Increased BPA levels were associated with increased levels of F2-isoprostane (ng/ml) (P = 0.02), with a similar trend for DEHP metabolites. Each log unit increase of high molecular weight (HMW) phthalate metabolites was associated with a 0.550 increase in Homeostatic Model Assessment of insulin resistance (HOMA-IR) units (P = 0.019) and altered circulating levels of activated endothelial cell-derived microparticles (% per ml) (P = 0.026). Bisphenol S (BPS), a replacement for BPA, was associated with increased albumin (mg):creatinine (g) ratio (P = 0.04). Metabolites of HMW phthalates were also associated with decreased brachial artery distensibility (P = 0.047).

CONCLUSION

Exposure to bisphenols and phthalates, including a BPA replacement, is associated with increased oxidant stress, insulin resistance, albuminuria, as well as disturbances in vascular function in healthy children.

Metabolism disrupting chemicals and metabolic disorders

The recent epidemics of metabolic diseases, obesity, type 2 diabetes(T2D), liver lipid disorders and metabolic syndrome have largely been attributed to genetic background and changes in diet, exercise and aging. However, there is now considerable evidence that other environmental factors may contribute to the rapid increase in the incidence of these metabolic diseases. This review will examine changes to the incidence of obesity, T2D and non-alcoholic fatty liver disease (NAFLD), the contribution of genetics to these disorders and describe the role of the endocrine system in these metabolic disorders. It will then specifically focus on the role of endocrine disrupting chemicals (EDCs) in the etiology of obesity, T2D and NAFLD while finally integrating the information on EDCs on multiple metabolic disorders that could lead to metabolic syndrome. We will specifically examine evidence linking EDC exposures during critical periods of development with metabolic diseases that manifest later in life and across generations.

The influence of phthalates and bisphenol A on the obesity development and glucose metabolism disorders

The prevalence of obesity and type 2 diabetes mellitus epidemics presents a great health problem worldwide. Beside the changes in diet and decreased physical activity, there is growing interest in endocrine disrupting chemicals that may have effects on these conditions. Among them, the role of certain phthalates and bisphenol A is confirmed. We have summarized the existing literature on this issue including cross-sectional, follow up epidemiological studies and in vivo and in vitro studies. Most data support the effects of bisphenol A and some phthalates, such as di-2-ethyl-hexyl phthalate, diethyl phthalate, dibuthyl phthalate, dimethyl phthalate, dibenzyl phthalate, diisononyl phthalate and others on the development obesity and type 2 diabetes mellitus. These endocrine disrupting chemicals interfere with different cell signaling pathways involved in weight and glucose homeostasis. Since the data are rather inconsistent, there is a need for new, well-designed prospective studies.

The Effects of Endocrine Disruptors on Adipogenesis and Osteogenesis in Mesenchymal Stem Cells: A Review

Endocrine-disrupting chemicals (EDCs) are prevalent in the environment, and epidemiologic studies have suggested that human exposure is linked to chronic diseases, such as obesity and diabetes. In vitro experiments have further demonstrated that EDCs promote changes in mesenchymal stem cells (MSCs), leading to increases in adipogenic differentiation, decreases in osteogenic differentiation, activation of pro-inflammatory cytokines, increases in oxidative stress, and epigenetic changes. Studies have also shown alteration in trophic factor production, differentiation ability, and immunomodulatory capacity of MSCs, which have significant implications to the current studies exploring MSCs for tissue engineering and regenerative medicine applications and the treatment of inflammatory conditions. Thus, the consideration of the effects of EDCs on MSCs is vital when determining potential therapeutic uses of MSCs, as increased exposure to EDCs may cause MSCs to be less effective therapeutically. This review focuses on the adipogenic and osteogenic differentiation effects of EDCs as these are most relevant to the therapeutic uses of MSCs in tissue engineering, regenerative medicine, and inflammatory conditions. This review will highlight the effects of EDCs, including organophosphates, plasticizers, industrial surfactants, coolants, and lubricants, on MSC biology.

Association of Urinary Phthalates with Self-Reported Eye Affliction/Retinopathy in Individuals with Diabetes: National Health and Nutrition Examination Survey, 2001-2010

Background. An epidemiological association between exposure to phthalates and type 2 diabetes (T2D) is known. However, the potential role of environmental phthalates in the complications of T2D is unknown. Methods. Using data from the National Health and Nutrition Examination Survey (NHANES) 2001-2010, we studied the association of 12 urinary phthalate metabolites with self-reported eye affliction/retinopathy in 1,004 participants with diabetes. Data from retinal imaging was used to validate this outcome. Independence of the phthalates→T2D association was studied by adjusting for age, sex, race, marital status, educational attainment, poverty income ratio, physical activity, glycated hemoglobin levels, total serum cholesterol, serum high-density lipoprotein cholesterol, serum triglycerides, blood pressure, duration of diabetes, total calorie intake, and obesity. Results. Self-reported eye affliction/retinopathy had 82% accuracy with Cohen's kappa of 0.31 (p < 0.001). Urinary mono-n-octyl phthalate (MOP) was independently associated with the likelihood of self-reported eye affliction/retinopathy in subjects with T2D after accounting for all the confounders. This significance of this association was robust to the potential misclassification in cases and controls of retinopathy. Further, a significant dose-response relationship between MOP and self-reported eye affliction/retinopathy was demonstrable. Conclusions. We show a novel epidemiological link between the environment and diabetic complications in NHANES 2001-2010 participants.

Di-(2-Ethylhexyl)-Phthalate (DEHP) Causes Impaired Adipocyte Function and Alters Serum Metabolites

Di-(2-ethylhexyl)-phthalate (DEHP), an ubiquitous environmental contaminant, has been shown to cause adverse effects on glucose homeostasis and insulin sensitivity in epidemiological studies, but the underlying mechanisms are still unknown. We therefore tested the hypothesis that chronic DEHP exposure causes impaired insulin sensitivity, affects body weight, adipose tissue (AT) function and circulating metabolic parameters of obesity resistant 129S6 mice in vivo. An obesity-resistant mouse model was chosen to reduce a potential obesity bias of DEHP effects on metabolic parameters and AT function. The metabolic effects of 10-weeks exposure to DEHP were tested by insulin tolerance tests and quantitative assessment of 183 metabolites in mice. Furthermore, 3T3-L1 cells were cultured with DEHP for two days, differentiated into mature adipocytes in which the effects on insulin stimulated glucose and palmitate uptake, lipid content as well as on mRNA/protein expression of key adipocyte genes were investigated. We observed in female mice that DEHP treatment causes enhanced weight gain, fat mass, impaired insulin tolerance, changes in circulating adiponectin and adipose tissue Pparg, adiponectin and estrogen expression. Serum metabolomics indicated a general increase in phospholipid and carnitine concentrations. In vitro, DEHP treatment increases the proliferation rate and alters glucose uptake in adipocytes. Taken together, DEHP has significant effects on adipose tissue (AT) function and alters specific serum metabolites. Although, DEHP treatment led to significantly impaired insulin tolerance, it did not affect glucose tolerance, HOMA-IR, fasting glucose, insulin or triglyceride serum concentrations. This may suggest that DEHP treatment does not cause impaired glucose metabolism at the whole body level.