Perinatal exposure of mice to the pesticide DDT impairs energy expenditure and metabolism in adult female offspring

Consensus on the key characteristics of metabolism disruptors

Metabolism-disrupting agents (MDAs) are chemical, infectious or physical agents that increase the risk of metabolic disorders. Examples include pharmaceuticals, such as antidepressants, and environmental agents, such as bisphenol A. Various types of studies can provide evidence to identify MDAs, yet a systematic method is needed to integrate these data to help to identify such hazards. Inspired by work to improve hazard identification of carcinogens using key characteristics (KCs), we developed 12 KCs of MDAs based on our knowledge of processes underlying metabolic diseases and the effects of their causal agents: (1) alters function of the endocrine pancreas; (2) impairs function of adipose tissue; (3) alters nervous system control of metabolic function; (4) promotes insulin resistance; (5) disrupts metabolic signalling pathways; (6) alters development and fate of metabolic cell types; (7) alters energy homeostasis; (8) causes inappropriate nutrient handling and partitioning; (9) promotes chronic inflammation and immune dysregulation in metabolic tissues; (10) disrupts gastrointestinal tract function; (11) induces cellular stress pathways; and (12) disrupts circadian rhythms. In this Consensus Statement, we present the logic that revealed the KCs of MDAs and highlight evidence that supports the identification of KCs. We use chemical, infectious and physical agents as examples to illustrate how the KCs can be used to organize and use mechanistic data to help to identify MDAs.

Bisphenol A and DDT disrupt adipocyte function in the mammary gland: implications for breast cancer risk and progression

As breast cancer incidence continues to rise worldwide, there is a pressing need to understand the environmental factors that contribute to its development. Obesogens, including Bisphenol A (BPA) and Dichlorodiphenyltrichloroethane (DDT), are highly prevalent in the environment, and have been associated with obesity and metabolic dysregulation. BPA and DDT, known to disrupt hormone signaling in breast epithelial cells, also promote adipogenesis, lipogenesis, and adipokine secretion in adipose tissue, directly contributing to the pathogenesis of obesity. While the adipose-rich mammary gland may be particularly vulnerable to environmental obesogens, there is a scarcity of research investigating obesogen-mediated changes in adipocytes that drive oncogenic transformation of breast epithelial cells. Here, we review the preclinical and clinical evidence linking BPA and DDT to impaired mammary gland development and breast cancer risk. We discuss how the obesogen-driven mechanisms that contribute to obesity, including changes in adipogenesis, lipogenesis, and adipokine secretion, could provide a pro-inflammatory, nutrient-rich environment that promotes activation of oncogenic pathways in breast epithelial cells. Understanding the role of obesogens in breast cancer risk and progression is essential for informing public health guidelines aimed at minimizing obesogen exposure, to ultimately reduce breast cancer incidence and improve outcomes for women.

Persistent organochlorine pesticides and cardiometabolic outcomes among middle-aged Latina women in a California agricultural community: The CHAMACOS Maternal Cognition Study

OBJECTIVE

Environmental exposure to endocrine disrupting compounds is hypothesized to increase risk of cardiovascular disease through effects on obesity, hypertension, dyslipidemia, and insulin resistance. We examined the relationship between serum concentrations of persistent organochlorine pesticides and biologic markers of inflammation and cardiometabolic disease, measured over a decade later, in a cohort of middle-aged and primarily immigrant Latina women living in an underserved agricultural community in California.

MATERIAL AND METHODS

We used data from the Center for the Health Assessment of Mothers and Children of Salinas-Maternal Cognition Study (CHAMACOS-MCS). We included 468 women who had concentrations of organochlorine pesticides measured in serum collected in 2009-2011 and complete follow-up data in 2022-2024 (blood draw, anthropometry, personal interview). We used Bayesian hierarchical regression models (BHM) to examine the independent effects of five highly correlated pesticides with continuous and binary measures of cardiometabolic disease and inflammation.

RESULTS

Participants averaged 49.0 (±5.5) years at follow-up. In BHM models, a 10-fold increase in p,p'-dichlorodiphenyltrichloroethane (DDT) and β-hexacyclohexane (β-HCH) was positively associated with BMI (DDT: adj-β = 1.26, 95 % Credible Interval (CrI): 0.33, 2.20; β-HCH: adj-β = 1.56, 95 %CrI: 0.45, 2.67) and waist circumference (DDT: adj-β = 2.75, 95 %CrI: 0.65, 4.85; β-HCH: adj-β = 3.74, 95 %CrI: 1.24, 6.23). Although credible intervals crossed the null, consistent positive associations were observed for DDT and β-HCH with blood pressure and for DDT with insulin resistance. Trans-nonachlor was positively associated with triglycerides (log-TRIG: adj-β = 0.08, 95 %CrI: 0.02, 0.13). β-HCH was positively associated with inflammatory markers (log-hsCRP: adj-β = 0.11, 95 %CrI: 0.03, 0.19; log-IL-6: adj-β = 0.08, 95 %CrI: 0.03, 0.14).

CONCLUSION

With over a decade of follow-up, we extend evidence on previously reported associations of DDT and β-HCH with several measures of obesity. In addition, we provide new evidence suggesting associations with biomarkers of blood pressure, insulin resistance, dyslipidemia and inflammation, supporting the hypothesis that exposure may have long-term influences on cardiovascular disease risk.

Volatile organic compounds exposure in relation to glucose homeostasis and type 2 diabetes in older adults from the NHANES

The impact of volatile organic compounds (VOCs) on type 2 diabetes (T2D) among older adults is unknown. The multiple linear regression model and the multiple binary logistic regression were used to evaluate the relationships between mVOCs and glucose homeostasis/T2D, respectively. Among the 19 mVOCs, the higher levels of urinary N-acetyl-S-(2-hydroxypropyl)-L-cysteine (2HPMA, compound CID:44146439) and N-acetyl-S-(2-hydroxypropyl)-L-cysteine (HPMMA, compound CID:107774684) were significantly associated with higher odds of T2D (OR = 1.16, 95% confidence interval [CI]:1.01-1.34 for 2HPMA; and OR = 1.27, 95% CI:1.04-1.54 for HPMMA). In addition, higher concentrations of multiple mVOCs in urine were significantly correlated with glucose homeostasis biomarkers, including 2HPMA and 2-thioxothiazolidine-4-carboxylic acid (TTCA, compound CID:3034757) with fasting glucose, HPMMA and mandelic acid (MA, compound CID:1292) with HbA1c, phenylglyoxylic acid (PGA, compound CID:11915) with serum insulin, HbA1c and HOMA-IR. Our findings suggested that exposure to VOCs were associated with increased odds of T2D in older adults, which might be mediated by impaired glucose homeostasis. Mitigating VOCs should be a necessary component of public health strategies aimed at reducing the burden of type 2 diabetes.

Obesogens and Energy Homeostasis: Definition, Mechanisms of Action, Exposure, and Adverse Effects on Human Health

BACKGROUND

Obesity is a major risk factor for noncommunicable diseases and is associated with a reduced life expectancy of up to 20 years, as well as with other consequences such as unemployment and increased economic burden for society. It is a multifactorial disease, and physiopathology of obesity involves dysregulated calorie utilization and energy balance, disrupted homeostasis of appetite and satiety, lifestyle factors including sedentary lifestyle, lower socioeconomic status, genetic predisposition, epigenetics, and environmental factors. Some endocrine-disrupting chemicals (EDCs) have been proposed as "obesogens" that stimulate adipogenesis leading to obesity. In this review, definition of obesogens, their adverse effects, underlying mechanisms, and metabolic implications will be updated and discussed.

SUMMARY

Disruption of lipid homeostasis by EDCs involves multiple mechanisms including increase in the number and size of adipocytes, disruption of endocrine-regulated adiposity and metabolism, alteration of hypothalamic regulation of appetite, satiety, food preference and energy balance, and modification of insulin sensitivity in the liver, skeletal muscle, pancreas, gastrointestinal system, and the brain. At a cellular level, obesogens can exert their endocrine disruptive effects by interfering with peroxisome proliferator-activated receptors and steroid receptors. Human exposure to chemical obesogens mainly occurs by ingestion and, to some extent, by inhalation and dermal uptake, usually in an unconscious manner. Persistent pollutants are lipophilic features; thus, they bioaccumulate in adipose tissue.

KEY MESSAGES

Although there are an increasing number of reports studying the effects of obesogens, their mechanisms of action remain to be elucidated. In addition, epidemiological studies are needed in order to evaluate human exposure to obesogens.

Adolescent F-53B exposure induces ovarian toxicity in rats: Autophagy-apoptosis interplay

As a substitute for perfluorooctane sulfonates, F-53B has permeated into the environment and can reach the human body through the food chain. Adolescent individuals are in a critical stage of development and may be more sensitive to the impacts of F-53B. In the present study, we modeled the exposure of adolescent female rats by allowing them free access to F-53B at concentrations of 0 mg/L, 0.125 mg/L, and 6.25 mg/L in drinking water, aiming to simulate the exposure in the adolescent population. Using the ovary as the focal point, we investigated the impact of developmental exposure to F-53B on female reproduction. The results indicated that F-53B induced reproductive toxicity in adolescent female rats, including ovarian lesions, follicular dysplasia and hormonal disorders. In-depth investigations revealed that F-53B induced ovarian oxidative stress, triggering autophagy within the ovaries, and the autophagy exhibited the interplay with apoptosis in turn, collectively leading to significant ovarian toxicity. Our findings provided deeper insights into the roles of the autophagy-apoptosis interplay in ovarian toxicity, and offered a new perspective on the developmental toxicity inflicted by adolescent F-53B exposure.

Effects of the Fungicide Prothioconazole on Lipid Metabolism in Mice: Whitening Alterations of Brown Adipose Tissue

With considerable concerns about the associations between metabolic disorders and agricultural biocides, there are scattered data suggesting that the triazole fungicide prothioconazole (PTC) at lower doses than the no observed adverse effect level of 5000 μg/kg/d possibly has the potential to disrupt glycolipid metabolism in mammals. Here, we investigated the effects of 50, 500, and 5000 μg/kg/d of PTC on glycolipid metabolism in mice following 8 weeks of administration via drinking water, with specific attention on brown adipose tissue (BAT) and white adipose tissue (WAT) in addition to the liver. We found that along with the increased serum triglyceride level in the 5000 μg/kg/d group, small fatty vacuoles occurred in livers in all treatment groups, indicating lipid accumulation. No change in WAT was observed, but PTC caused BAT whitening, characterized by adipocyte hypertrophy, more unilocular adipocytes with enlarged lipid droplets, reduced UCP1 levels, and down-regulated Doi2 expression, and even the dose of 50 μg/kg/d was effective. Transcriptomic analysis revealed immune inhibition and circadian rhythm disturbance in BAT from the 5000 μg/kg/d group, which are in agreement with BAT whitening and inactivation. On employing the C3H10T1/2 cells in vitro, we found that PTC treatment concentration-dependently promoted lipid accumulation in brown adipocytes, along with altered expression of thermogenesis-related and circadian genes. Taken together, our study shows that low doses of PTC caused BAT whitening, calling for much attention to the new target by pollutants.

A new insight into the mechanism of dichlorodiphenyltrichloroethane-induced hepatotoxicity based on GSDME-mediated pyroptosis

There have been persistent concerns about the safety risks associated with DDT residues in the environment. Studies have shown that exposure to DDT or its metabolites can cause various liver diseases. However, the mechanisms of liver toxicity haven't been well studied. In our current investigation, we observed that DDT triggers pyroptosis in human liver cells (HL-7702), representing a novel form of programmed cell death. Our results delineated DDT (0-100 μM) induced pyroptosis in HL-7702 cells, which was confirmed through morphological changes, lactate dehydrogenase (LDH) release, gasdermin E (GSDME) cleavage and Annexin-V/PI staining. Knockdown of GSDME reduced cell death and transferred the mode of cell death from pyroptosis to apoptosis. Notably, DDT exposure markedly increased reactive oxygen species (ROS) production, concurrent with c-Jun N-terminal kinase (JNK) phosphorylation. Intervention with a ROS inhibitor or JNK inhibitor SP600125 restored cell viability and hindered GSDME-mediated pyroptosis. Our results firstly demonstrate that DDT suppresses HL-7702 cells growth by inducing pyroptosis mainly through the ROS/JNK/GSDME pathway. These findings not only contribute to an in-depth understanding of DDT toxicity but also open avenues for gaining valuable insights into potential mitigation strategies and therapeutic interventions.

Impaired energy expenditure following exposure to either DDT or DDE in mice may be mediated by DNA methylation changes in brown adipose

The insecticide dichlorodiphenyltrichloroethane (DDT) and its persistent metabolite, dichlorodiphenyldichloroethylene (DDE), have been associated with increased adiposity and obesity in multiple generations of rodents and humans. These lipophilic pollutants accumulate in adipose tissue and appear to decrease energy expenditure through the impairment of thermogenesis in brown adipose tissue (BAT). We hypothesized that impaired thermogenesis is due to persistent epigenetic modifications of BAT. To address this, we exposed C57BL/6 J mice to DDT or DDE from gestational day (GD) 11.5 to postnatal day (PND) 5, evaluated longitudinal body temperature, and performed reduced representation bisulfite sequencing and RNA sequencing of BAT from infant and adult offspring. Exposure to DDT or DDE reduced core body temperature in adult mice, and differential methylation at the pathway and gene level was persistent from infancy to adulthood. Furthermore, thermogenesis and biological pathways essential for thermogenic function, such as oxidative phosphorylation and mechanistic target of rapamycin kinase (mTOR) signaling, were enriched with differential methylation and RNA transcription in adult mice exposed to DDT or DDE. PAZ6 human brown preadipocytes were differentiated in the presence of DDT or DDE to understand the brown adipocyte-autonomous effect of these pollutants. In vitro exposure led to limited changes in RNA expression; however, mitochondrial membrane potential was decreased in vitro with 0.1 µM and 1 µM doses of DDT or DDE. These results demonstrate that concentrations of DDT and DDE relevant to human exposure have a significant effect on thermogenesis, the transcriptome, and DNA methylome of mouse BAT and the mitochondrial function of human brown adipocytes.

Adaptation of Brown Adipose Tissue in Response to Chronic Exposure to the Environmental Pollutant 1,1-Dichloro-2,2-bis(p-chlorophenyl) Ethylene (DDE) and/or a High-Fat Diet in Male Wistar Rats

Brown adipose tissue (BAT) participates in thermogenesis and energy homeostasis. Studies on factors capable of influencing BAT function, such as a high-fat diet (HFD) or exposure to environmental pollutants, could be useful for finding metabolic targets for maintaining energy homeostasis. We evaluated the effect of chronic exposure to dichlorodiphenyldichloroethylene (DDE), the major metabolite of dichlorodiphenyltrichloroethane (DDT), and/or a HFD on BAT morphology, mitochondrial mass, dynamics, and oxidative stress in rats. To this end, male Wistar rats were treated for 4 weeks with a standard diet, or a HFD alone, or together with DDE. An increase in paucilocular adipocytes and the lipid droplet size were observed in HFD-treated rats, which was associated with a reduction in mitochondrial mass and in mitochondrial fragmentation, as well as with increased oxidative stress and upregulation of the superoxide dismutase-2. DDE administration mimics most of the effects induced by a HFD on BAT, and it aggravates the increase in the lipid droplet size when administered together with a HFD. Considering the known role of oxidative stress in altering BAT functionality, it could underlie the ability of both DDE and a HFD to induce similar metabolic adaptations in BAT, leading to reduced tissue thermogenesis, which can result in a predisposition to the onset of energy homeostasis disorders.

Adipose Tissue Dysfunction Related to Climate Change and Air Pollution: Understanding the Metabolic Consequences

Obesity, a global pandemic, poses a major threat to healthcare systems worldwide. Adipose tissue, the energy-storing organ during excessive energy intake, functions as a thermoregulator, interacting with other tissues to regulate systemic metabolism. Specifically, brown adipose tissue (BAT) is positively associated with an increased resistance to obesity, due to its thermogenic function in the presence of uncoupled protein 1 (UCP1). Recently, studies on climate change and the influence of environmental pollutants on energy homeostasis and obesity have drawn increasing attention. The reciprocal relationship between increasing adiposity and increasing temperatures results in reduced adaptive thermogenesis, decreased physical activity, and increased carbon footprint production. In addition, the impact of climate change makes obese individuals more prone to developing type 2 diabetes mellitus (T2DM). An impaired response to heat stress, compromised vasodilation, and sweating increase the risk of diabetes-related comorbidities. This comprehensive review provides information about the effects of climate change on obesity and adipose tissue, the risk of T2DM development, and insights into the environmental pollutants causing adipose tissue dysfunction and obesity. The effects of altered dietary patterns on adiposity and adaptation strategies to mitigate the detrimental effects of climate change are also discussed.

Weighing in on the role of brown adipose tissue for treatment of obesity

Brown adipose tissue (BAT) activation is an emerging target for obesity treatments due to its thermogenic properties stemming from its ability to shuttle energy through uncoupling protein 1 (Ucp1). Recent rodent studies show how BAT and white adipose tissue (WAT) activity can be modulated to increase the expression of thermogenic proteins. Consequently, these alterations enable organisms to endure cold-temperatures and elevate energy expenditure, thereby promoting weight loss. In humans, BAT is less abundant in obese subjects and impacts of thermogenesis are less pronounced, bringing into question whether energy expending properties of BAT seen in rodents can be translated to human models. Our review will discuss pharmacological, hormonal, bioactive, sex-specific and environmental activators and inhibitors of BAT to determine the potential for BAT to act as a therapeutic strategy. We aim to address the feasibility of utilizing BAT modulators for weight reduction in obese individuals, as recent studies suggest that BAT's contributions to energy expenditure along with Ucp1-dependent and -independent pathways may or may not rectify energy imbalance characteristic of obesity.

Paternal DDT exposure induces sex-specific programming of fetal growth, placenta development and offspring's health phenotypes in a mouse model

Mounting evidence suggests that environmentally induced epigenetic inheritance occurs in mammals and that traits in the progeny can be shaped by parental environmental experiences. Epidemiological studies link parental exposure to environmental toxicants, such as the pesticide DDT, to health phenotypes in the progeny, including low birth and increased risk of chronic diseases later in life. Here, we show that the progeny of male mice exposed to DDT in the pre-conception period are born smaller and exhibit sexual dimorphism in metabolic function, with male, but not female, offspring developing severe glucose intolerance compared to controls. These phenotypes in DDT offspring were linked to reduced fetal growth and placenta size as well as placenta-specific reduction of glycogen levels and the nutrient sensor and epigenetic regulator OGT, with more pronounced phenotypes observed in male placentas. However, placenta-specific genetic reduction of OGT only partially replicates the metabolic phenotype observed in offspring of DDT-exposed males. Our findings reveal a role for paternal pre-conception environmental experiences in shaping placenta development and in fetal growth restriction. While many questions remain, our data raise the tantalizing possibility that placenta programming could be a mediator of environmentally induced intergenerational epigenetic inheritance of phenotypes and needs to be further evaluated.

Hepatic oxylipin profiles in mouse models of Wilson disease: New insights into early hepatic manifestations

Hepatic inflammation is commonly identified in Wilson disease (WD), a genetic disease of hepatic and brain copper accumulation. Copper accumulation is associated with increased oxidative stress and reactive oxygen species generation which may result in non-enzymatic oxidation of membrane-bound polyunsaturated fatty acids (PUFA). PUFA can be oxidized enzymatically via lipoxygenases (LOX), cyclooxygenases (COX), and cytochrome P450 monooxygenases (CYP). Products of PUFA oxidation are collectively known as oxylipins (OXL) and are bioactive lipids that modulate hepatic inflammation. We examined hepatic OXL profiles at early stages of WD in two mouse models, the toxic milk mouse from The Jackson Laboratory (tx-j) and the Atp7b knockout on a C57Bl/6 background (Atp7b-/-B6). Targeted lipidomic analysis performed by ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry showed that in both tx-j and Atp7b-/-B6 mice, hepatic OXL profiles were altered with higher thromboxane and prostaglandins levels. The levels of oxidative stress marker, 9-HETE were increased more markedly in tx-j mice. However, both genotypes showed upregulated transcript levels of many genes related to oxidative stress and inflammation. Both genotypes showed higher prostaglandins, thromboxin along with higher PUFA-derived alcohols, diols, and ketones with altered epoxides; the expression of Alox5 was upregulated and many CYP-related genes were dysregulated. Pathway analyses show dysregulation in arachidonic acid and linoleic acid metabolism characterizes mice with WD. Our findings indicate alterations in hepatic PUFA metabolism in early-stage WD and suggest the upregulation of both, non-enzymatic ROS-dependent and enzymatic PUFA oxidation, which could have implications for hepatic manifestations in WD and represent potential targets for future therapies.

Associations of chronic exposure to a mixture of pesticides and type 2 diabetes mellitus in a Chinese elderly population

Epidemiological studies have related exposure to pesticides to increased risk of diabetes. However, few studies have evaluated the health effects of mixed pesticides exposure, especially in an elderly population. Here, we utilized gas chromatography-tandem mass spectrometry to quantify the levels of 39 pesticides in 4 categories in a Chinese elderly population. Then we used general linear models to explore the association between individual pesticide exposure and type 2 diabetes mellitus (T2DM). Restricted cubic spline (RCS) models were fitted to identify potential non-linearities between those associations. Furthermore, stratified analysis by gender was conducted to explore the gender-specific associations. Finally, we used weighted quantile sum (WQS) regression, quantile-based g computation (qgcomp), and Bayesian kernel machine regression (BKMR) to evaluate the effects of mixed exposure to 39 pesticides. The results showed that exposure to pesticides was associated with high risk of T2DM, with β-Hexachlorocyclohexane (β-BHC) and oxadiazon being the most significant independent contributors, which was pronounced among elderly women. Moreover, the association of β-BHC and oxadiazon with T2DM was linear. These indicated that it is an urgent need to take practical measures to control these harmful pesticides.

DNA methylation reprogramming mediates transgenerational diabetogenic effect induced by early-life p,p'-DDE exposure

Increasing evidence shows that an adverse environment during the early fetal development can affect the epigenetic modifications on a wide range of diabetes-related genes, leading to an increased diabetic susceptibility in adulthood or even in subsequent generations. p,p'-Dichlorodiphenoxydichloroethylene (p,p'-DDE) is a break-down product of the pesticide dichlorodiphenyltrichloroethane (DDT). p,p'-DDE has been associated with various health concerns, such as diabetogenic effect. However, the precise molecular mechanism remains unclear. In this study, p,p'-DDE was given by gavage to pregnant rat dams from gestational day (GD) 8 to GD15 to generate male germline to investiagate the transgenerational effects. We found that early-life p,p'-DDE exposure increased the transgenerational diabetic susceptibility through male germline inheritance. In utero exposure to p,p'-DDE altered the sperm DNA methylome in F1 progeny, and a significant number of those differentially methylated genes could be inherited by F2 progeny. Furthermore, early-life p,p'-DDE exposure altered DNA methylation in glucose metabolic genes Gck and G6pc in sperm and the methylation modification were also found in liver of the next generation. Our study demonstrate that DNA methylation plays a critical role in mediating transgenerational diabetogenic effect induced by early-life p,p'-DDE exposure.

The brominated flame retardant tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) as well as hexabromocyclododecane lead to lipid disorders in mice

The brominated flame retardant tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) (TBBPA-DBMPE) is a recommended substitute for hexabromocyclododecane (HBCD), a banned persistent organic pollutant, yet its potential toxicities remains largely unexplored. Here, we investigated the effects of a long-term exposure to TBBPA-DBMPE at nominal doses of 50 and 1000 μg/kg/d on lipid homeostasis in CD-1 mice, in comparison with 50 μg/kg/d HBCD as a positive control. Male pups received chemical treatments through maternal administration via drinking water from postnatal day 0-21, followed by direct administration through drinking water after weaning. On the 23rd week after treatment, the oral lipid tolerance test revealed that low-dose TBBPA-DBMPE as well as HBCD affected lipid tolerance, although the fasting serum triglyceride (TG) levels were not altered. When chemical treatment was extended to the 32nd week, TBBPA-DBMPE-treated animals displayed adipocyte hypertrophy in both white adipose tissue (eWAT) and brown adipose tissue (BAT) and hepatic steatosis, which was largely consistent with the effects of HBCD. These findings indicate that like HBCD, TBBPA-DBMPE led to increased lipid load in mice. Interestingly, we also observed intestinal histological changes, coupled with increased expression of lipid absorption-related genes in both HBCD and TBBPA-DBMPE treatments, suggesting increased lipid absorption. This was supported by in vitro findings that both HBCD and TBBPA-DBMPE promoted lipid accumulation in IEC-6 cells under the stress of oleic acid for 6 h, implying that altered lipid absorption by the intestine may partly contributed to increased lipid load in mice. Overall, the effects of 50 μg/kg/d TBBPA-DBMPE in terms of some parameters were comparable with 50 μg/kg/d HBCD, suggesting that TBBPA-DBMPE may not be an ideal substitute of HBCD.

Perinatal triphenyl phosphate exposure induces metabolic dysfunctions through the EGFR/ERK/AKT signaling pathway: Mechanistic in vitro and in vivo studies

Triphenyl phosphate (TPhP), a widely used organophosphate-flame retardant, is ubiquitously found in household environments and may adversely affect human health. Evidence indicates that TPhP exposure causes metabolic dysfunctions in vivo; however, the underlying mechanism of such adverse effects has not been comprehensively investigated. Herein, we utilized two in vitro models including mouse and human preadipocytes to delineate adipogenic mechanisms of TPhP. The results revealed that both mouse and human preadipocytes exposed to TPhP concentration-dependently accumulated more fat through a significant upregulation of epidermal growth factor receptor (EGFR). We demonstrated that TPhP significantly promoted adipogenesis through the activation of EGFR/ERK/AKT signaling pathway as evident by a drastic reduction in adipogenesis of preadipocytes cotreated with inhibitors of EGFR and its major effectors. Furthermore, we confirmed the mechanism of TPhP-induced metabolic dysfunctions in vivo. We observed that male mice perinatally exposed to TPhP had a significant increase in adiposity, hepatic triglycerides, insulin resistance, plasma insulin levels, hypotension, and phosphorylated EGFR in gonadal fat. Interestingly, an administration of a potent and selective EGFR inhibitor significantly ameliorated the adverse metabolic effects caused by TPhP. Our findings uncovered a potential mechanism of TPhP-induced metabolic dysfunctions and provided implications on toxic metabolic effects posed by environmental chemicals.

Differential contributions of the gut microbiota and metabolome to pathomechanisms in ulcerative colitis: an in vitro analysis

The gut microbiota has been implicated in onset and progression of ulcerative colitis (UC). Here, we assess potential causal involvement of the microbiota and -associated fecal water (FW) metabolome in altering key functional parameters of the colonic epithelium. Fecal samples were collected from N = 51 healthy controls (HC), N = 36 patients with active UC (UC-A), and N = 41 subjects in remission N = 41 (UC-R). Using in vitro incubation experiments, the FW metabolome's impact on butyrate oxidation rates/gene expression and cell death (cytotoxicity) of HT-29 cells, cytokine production by PBMC, and barrier integrity of Caco2 monolayers was evaluated. The FW metabolome from patients and individuals hosting the Bacteroides 2 (Bact2) enterotype (69% of UC-A, 31% of UC-R, 3% of HC), characterized by lower levels of median- and short-chain fatty acids and furan compounds, left butyrate oxidation rates unaltered but affected associated gene expression profiles. UC patients/Bact2-carriers' FW lowered PBMC IL-8 production and increased IL-1β production. Patients' FW increased cytotoxicity, associated with sulfide compound levels. Bact2 carriers' FW, displaying higher levels of bile acids, lowered barrier function upon incubation of monolayers. The FW metabolome of patients and individuals hosting a dysbiotic microbiota could contribute to the disruption of functional processes of the colonic epithelium as observed in UC.

Prenatal exposures to mixtures of endocrine disrupting chemicals and sex-specific associations with children's BMI and overweight at 5.5 years of age in the SELMA study

BACKGROUND

Prenatal exposure to mixtures of endocrine disrupting chemicals (EDC) has the potential to disrupt human metabolism. Prenatal periods are especially sensitive as many developmental processes are regulated by hormones. Prenatal exposure to EDCs has inconsistently been associated with children's body mass index (BMI) and obesity. The objective of this study was to investigate if prenatal exposure to a mixture of EDCs was associated with children's BMI and overweight (ISO-BMI ≥ 25) at 5.5 years of age, and if there were sex-specific effects.

METHODS

A total of 1,105 mother-child pairs with complete data on prenatal EDCs concentrations (e.g., phthalates, non-phthalate plasticizers, phenols, PAH, pesticides, PFAS, organochlorine pesticides, and PCBs), children's measured height and weight, and selected covariates in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy (SELMA) study were included in this analysis. The mixture effect of EDCs with children's BMI and overweight was assessed using WQS regression with 100 repeated holdouts. A positively associated WQS index with higher BMI and odds of overweight was derived. Models with interaction term and stratified weights by sex was applied in order to evaluate sex-specific associations.

RESULTS

A significant WQS*sex interaction term was identified and associations for boys and girls were in opposite directions. Higher prenatal exposure to a mixture of EDCs was associated with lower BMI (Mean β = -0.19, 95%CI: -0.40, 0.01) and lower odds of overweight (Mean OR = 0.72, 95%CI: 0.48, 1.04) among girls with borderline significance. However, the association among boys did not reach statistical significance. Among girls, the possible chemicals of concern were MEP, 2-OHPH, BPF, BPS, DPP and PFNA.

CONCLUSION

Prenatal exposure to a mixture of EDCs was associated with lower BMI and overweight among girls, and non-significant associations among boys. Chemicals of concern for girls included phthalates, non-phthalate plasticizers, bisphenols, PAHs, and PFAS.

Chlorothalonil induces obesity in mice by regulating host gut microbiota and bile acids metabolism via FXR pathways

As the most commonly used organochlorine pesticide nowadays, chlorothalonil (CHI), is ubiquitous in a natural environment and poses many adverse effects to organisms. Unfortunately, the toxicity mechanisms of CHI have not been clarified yet. This study found that the CHI based on ADI level could induce obesity in mice. In addition, CHI could induce an imbalance in the gut microbiota of mice. Furthermore, the results of the antibiotic treatment and gut microbiota transplantation experiments showed that the CHI could induce obesity in mice in a gut microbiota-dependent manner. Based on the results of targeted metabolomics and gene expression analysis, CHI could disturb the bile acids (BAs) metabolism of mice, causing the inhibition of the signal response of BAs receptor FXR and leading to glycolipid metabolism disorders in liver and epiWAT of mice. The administration of FXR agonist GW4064 and CDCA could significantly improve the CHI-induced obesity in mice. In conclusion, CHI was found to induce obesity in mice by regulating the gut microbiota and BAs metabolism via the FXR signaling pathway. This study provides evidence linking the gut microbiota and pesticides exposure with the progression of obesity, demonstrating the key role of gut microbiota in the toxic effects of pesticides.

The diabetogenic effects of pesticides: Evidence based on epidemiological and toxicological studies

While the use of pesticides has improved grain productivity and controlled vector-borne diseases, the widespread use of pesticides has resulted in ubiquitous environmental residues that pose health risks to humans. A number of studies have linked pesticide exposure to diabetes and glucose dyshomeostasis. This article reviews the occurrence of pesticides in the environment and human exposure, the associations between pesticide exposures and diabetes based on epidemiological investigations, as well as the diabetogenic effects of pesticides based on the data from in vivo and in vitro studies. The potential mechanisms by which pesticides disrupt glucose homeostasis include induction of lipotoxicity, oxidative stress, inflammation, acetylcholine accumulation, and gut microbiota dysbiosis. The gaps between laboratory toxicology research and epidemiological studies lead to an urgent research need on the diabetogenic effects of herbicides and current-use insecticides, low-dose pesticide exposure research, the diabetogenic effects of pesticides in children, and assessment of toxicity and risks of combined exposure to multiple pesticides with other chemicals.

Effects of endocrine disruptors on the electrical activity of leptin receptor neurons in the dorsomedial hypothalamus and anxiety-like behavior in male mice

There is increasing concern about the effects of endocrine disrupting chemicals (EDCs) on human health. Recently, some EDCs are suggested to affect energy metabolism leading to increased risk of obesity. Obesogenic effects of some EDCs on adipogenesis have been reported, however, there is no study examining their potential actions on the brain circuits controlling feeding and metabolism. We have investigated effects of tributyltin (TBT) and dichlorodiphenyltrichloroethane (p,p'-DDT) on electrical activity on dorsomedial hypothalamic leptin receptor neurons (DMH^LepR), morphological adaptations in neuronal anatomy of DMH^LepR, locomotion, and anxiety-like behaviors in mice. Twenty-three Lep-Cre transgenic mice were intracranially injected with GFP virus. Control animals received intraperitoneal corn oil alone while group 2 and 3 received TBT (25 μg/kg) and p,p'-DDT (2 mg/kg) for one month. Locomotor activity and anxiety-like behavior of the animals were determined by open field test. Electrophysiological effects of TBT and p,p'-DDT on DMH^LepR neurons were determined by patch clamp method. Neuronal anatomy was determined by confocal microscopy. Spontaneous firing frequency of DMH^LepR neurons of TBT group of mice was significantly higher than both p,p'-DDT and control groups (p < 0.01). TBT and p,p'-DDT significantly decreased frequency of the spontaneous inhibitory post-synaptic currents to DMH^LepR neurons compared to the control group (p < 0.05). The time spent in the center and the number of entrances to the center by the TBT-administered mice were significantly lower than other groups (p < 0.01). The total distance traveled and mean speed of the control group of mice were significantly higher than the p,p'-DDT- and TBT-administered animals (p < 0.0001). c-Fos activity of the p,p'-DDT- and TBT-administered animals were significantly elevated compared to the control group (p < 0.001), while no change in the number of dendritic spines were observed. In conclusion, this study demonstrates that exposure to TBT and p,p'-DDT alters electrical activity in DMH^LepR neurons and behavioral state in mice.

Perigestational exposure of a combination of a high-fat diet and pesticide impacts the metabolic and microbiotic status of dams and pups; a preventive strategy based on prebiotics

PURPOSE

Metabolic changes during the perinatal period are known to promote obesity and type-2 diabetes in adulthood via perturbation of the microbiota. The risk factors for metabolic disorders include a high-fat diet (HFD) and exposure to pesticide residues. The objective of the present study was to evaluate the effects of perigestational exposure to a HFD and chlorpyrifos (CPF) on glycemia, lipid profiles, and microbial populations in Wistar dams and their female offspring. We also tested a preventive strategy based on treatment with the prebiotic inulin.

METHODS

From 4 months before gestation to the end of the lactation period, six groups of dams were exposed to either a standard diet, a HFD alone, CPF alone, a combination of a HFD and CPF, and/or inulin supplementation. All female offspring were fed a standard diet from weaning to adulthood. We measured the impacts of these exposures on glycemia, the lipid profile, and the microbiota (composition, metabolite production, and translocation into tissues).

RESULTS

HFD exposure and CPF + HFD co-exposure induced dysmetabolism and an imbalance in the gut flora in both the dams and the female offspring. Inulin mitigated the impact of exposure to a HFD alone but not that of CPF + HFD co-exposure.

CONCLUSION

Our results provide a better understanding of the complex interactions between environmental pollutants and diet in early life, including in the context of metabolic diseases.

Metabolic Consequences of the Water We Drink: A Study Based on Field Evidence and Animal Model Experimentation

The effect of the chronic consumption of water contaminated with residual concentrations of DDT's metabolites (DDD-dichlorodiphenyldichloroethane and DDE-dichlorodiphenyldichloroethylene) found in the environment were evaluated on the biometric, hematological and antioxidant system parameters of the hepatic, muscular, renal and nervous tissues of Wistar rats. The results showed that the studied concentrations (0.002 mg.L^-1 of DDD plus 0.005 mg.L^-1 of DDE) could not cause significant changes in the hematological parameters. However, the tissues showed significant alteration in the activity of the antioxidant system represented by the increase in the activity of the enzymes gluthathione S-transferases in the liver, superoxide dismutase in the kidney, gluthathione peroxidase in the brain, and several changes in enzymatic activity in muscle (SOD, GPx and LPO). The enzymes alanine aminotransaminase (ALT) and aspartate aminotransaminase (AST) were also evaluated for the amino acids' metabolism in the liver, with ALT showing a significant increase in the exposed animals. In the integrative analysis of biomarkers (Permanova and PCOA), the studied concentrations showed possible metabolic changes and damage to cellular structures evidenced by increased oxidative stress and body weight gain among the treated animals. This study highlights the need for further studies on the impact of banned pesticides still present in soils that may induce adverse effects in organisms that may prevail in future generations and the environment.

Pesticides as endocrine disruptors: programming for obesity and diabetes

PURPOSE

Exposure to pesticides has been associated with obesity and diabetes in humans and experimental models mainly due to endocrine disruptor effects. First contact with environmental pesticides occurs during critical phases of life, such as gestation and lactation, which can lead to damage in central and peripheral tissues and subsequently programming disorders early and later in life.

METHODS

We reviewed epidemiological and experimental studies that associated pesticide exposure during gestation and lactation with programming obesity and diabetes in progeny.

RESULTS

Maternal exposure to organochlorine, organophosphate and neonicotinoids, which represent important pesticide groups, is related to reproductive and behavioral dysfunctions in offspring; however, few studies have focused on glucose metabolism and obesity as outcomes.

CONCLUSION

We provide an update regarding the use and metabolic impact of early pesticide exposure. Considering their bioaccumulation in soil, water, and food and through the food chain, pesticides should be considered a great risk factor for several diseases. Thus, it is urgent to reformulate regulatory actions to reduce the impact of pesticides on the health of future generations.

Subacute and low dose of tributyltin exposure leads to brown adipose abnormalities in male rats

Tributyltin (TBT) is an obesogenic endocrine disrupting chemical (EDC) linked with several metabolic complications. Brown adipose tissue (BAT) is the principal site for thermogenesis, making it a potential target for obesity management and metabolic disease. However, few studies have evaluated TBT effect on BAT function. In this investigation, we assessed whether subacute (15 days) and low dose of TBT exposure (100 ng/kg/day) results in abnormal BAT morphophysiology in adult male rats. Body temperature, BAT morphology, inflammation, oxidative stress, collagen deposition and BAT metabolic gene expression markers were assessed in room temperature (Room, ∼24 ºC) and after cold tolerance test (Cold, ∼4 ºC) conditions. A reduction in body temperature was observed in both Room and Cold conditions in TBT rats, suggesting abnormal BAT thermogenic function. Changes in BAT morphology were observed in TBT rats, with an increase in BAT lipid accumulation, an increase in BAT unilocular adipocyte number and a decrease in BAT multilocular adipocyte number in Room condition. All these parameters were opposite in Cold condition TBT rats, leading to a borderline increase in BAT UCP1 protein expression. An increase in BAT mast cell number was observed in TBT rats in Room condition. An increase in ED1 protein expression (macrophage marker) was observed in TBT rats in Cold condition. Oxidative stress and collagen deposition increased in both Room and Cold conditions in TBT rats. TBT exposure caused a borderline increase in BAT COL1A1 protein expression in Cold condition. Further, strong negative correlations were observed between body temperature and BAT lipid accumulation, and BAT lipid accumulation and multilocular adipocyte number. Thus, these data suggest that TBT exposure impaired BAT morphophysiology through impacts on lipid accumulation, inflammation, fibrosis and oxidative stress in male rats.

Investigation of dichlorodiphenyltrichloroethane (DDT) on xenobiotic enzyme disruption and metabolomic bile acid biosynthesis in DDT-sprayed areas using wild rats

Dichlorodiphenyltrichloroethane (DDT) is an organochlorine insecticide used worldwide. Several studies have reported the toxic effects of DDT and its metabolites on steroid hormone biosynthesis; however, its environmental effects are not well understood. This study examined wild rats collected in DDT-sprayed areas of South Africa and quantified plasma metabolites using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). Fold change analysis of the metabolome revealed the effect of DDT on bile acid biosynthesis. Gene expression of the related enzyme in rat liver samples was also quantified. Significant association was found between DDT and gene expression levels related to constitutive androstane receptor mediated enzymes, such as Cyp2b1 in rat livers. However, our results could not fully demonstrate that enzymes related to bile acid biosynthesis were strongly affected by DDT. The correlation between DDT concentration and gene expression involved in steroid hormone synthesis in testis was also evaluated; however, no significant correlation was found. The disturbance of metabolic enzymes occurred in rat liver in the target area. Our results suggest that DDT exposure affects gene expression in wild rats living in DDT-sprayed areas. Therefore, there is a need for DDT toxicity evaluation in mammals living in DDT-sprayed areas. We could not find an effective biomarker that could reflect the mechanism of DDT exposure; however, this approach can provide new insights for future research to evaluate DDT effects in sprayed areas.

Environmentally Induced Sperm RNAs Transmit Cancer Susceptibility to Offspring in a Mouse Model

DNA sequence accounts for the majority of disease heritability, including cancer. Yet, not all familial cancer cases can be explained by genetic factors. It is becoming clear that environmentally induced epigenetic inheritance occurs and that the progeny's traits can be shaped by parental environmental experiences. In humans, epidemiological studies have implicated environmental toxicants, such as the pesticide DDT, in intergenerational cancer development, including breast and childhood tumors. Here, we show that the female progeny of males exposed to DDT in the pre-conception period have higher susceptibility to developing aggressive tumors in mouse models of breast cancer. Sperm of DDT-exposed males exhibited distinct patterns of small non-coding RNAs, with an increase in miRNAs and a specific surge in miRNA-10b levels. Remarkably, embryonic injection of the entire sperm RNA load of DDT-exposed males, or synthetic miRNA-10b, recapitulated the tumor phenotypes observed in DDT offspring. Mechanistically, miR-10b injection altered the transcriptional profile in early embryos with enrichment of genes associated with cell differentiation, tissue and immune system development. In adult DDT-derived progeny, transcriptional and protein analysis of mammary tumors revealed alterations in stromal and in immune system compartments. Our findings reveal a causal role for sperm RNAs in environmentally induced inheritance of cancer predisposition and, if confirmed in humans, this could help partially explain some of the "missing heritability" of breast, and other, malignancies.

Environmental toxicants, brown adipose tissue, and potential links to obesity and metabolic disease

Rates of human obesity, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD) have risen faster than anticipated and cannot solely be explained by excessive caloric intake or physical inactivity. Importantly, this effect is also observed in many other domesticated and non-domesticated mammals, which has led to the hypothesis that synthetic environmental pollutants may be contributing to disease development. While the impact of these chemicals on appetite and adipogenesis has been extensively studied, their potential role in reducing energy expenditure is less studied. An important component of whole-body energy expenditure is adaptive and diet-induced thermogenesis in human brown adipose tissue (BAT). This review summarizes recent evidence that environmental pollutants such as the pesticide chlorpyrifos inhibit BAT function, diet-induced thermogenesis and the potential signaling pathways mediating these effects. Lastly, we discuss the importance of housing experimental mice at thermoneutrality, rather than room temperature, to maximize the translation of findings to humans.

National temporal trend for organophosphate pesticide DDT exposure and associations with chronic kidney disease using age-adapted eGFR model

Whilst certain environmental organochlorine pesticide exposure may still pose significant burden, the associations between dichloro-diphenyl-trichloroethane (DDT) and chronic kidney disease (CKD) remain disputable notwithstanding the potentially inaccurate disease definition between age groups. National DDT exposure burden atlas was depicted from 92,061 participants by measuring their serum concentrations of DDT congeners and major metabolite in the US from 1999 to 2016. Temporal analyses of these toxicant exposure suggested that although serum DDT concentrations exhibited recent decline, the detection rates remain up to 99.8% every year, posing great concern for exposure risk. A total of 3,039 US adults were further included from these participants demonstrating the weighted CKD prevalence of 40.2% using the new age-adapted CKD-EPI40 model compared to 28.0% using the current CKD-EPI method. After adjustment for covariates, logistic regression model results showed individual metabolites and total DDT burden were positively, yet monotonically, associated with risk of CKD incidence (P-trend for all < 0.05), particularly among adults 40 years of age and older. Much heightened renal disease risk was also observed with high DDT exposure (OR, 1.55; 95 % CI, 1.11-2.15) in those who were hypertensive (P for heterogeneity < 0.001) but not with diabetes. The current high DDT exposure risk combined with elevated probability for CKD incidence call for health concerns and management for the environmentally persistent pollutants.

Endocrine disruptor chemicals, adipokines and reproductive functions

The prevalence of adult obesity has risen markedly in recent decades. The endocrine system precisely regulates energy balance, fat abundance and fat deposition. Interestingly, white adipose tissue is an endocrine gland producing adipokines, which regulate whole-body physiology, including energy balance and reproduction. Endocrine disruptor chemicals (EDCs) include natural substances or chemicals that affect the endocrine system by multiple mechanisms and increase the risk of adverse health outcomes. Numerous studies have associated exposure to EDCs with obesity, classifying them as obesogens by their ability to activate different mechanisms, including the differentiation of adipocytes, increasing the storage of triglycerides, or elevating the number of adipocytes. Moreover, in recent years, not only industrial deception and obesity have intensified but also the problem of human infertility. Reproductive functions depend on hormone interactions, the balance of which may be disrupted by various EDCs or obesity. This review gives a brief summary of common EDCs linked with obesity, the mechanisms of their action, and the effect on adipokine levels, reproduction and connected disorders, such as polycystic ovarian syndrome, decrease in sperm motility, preeclampsia, intrauterine growth restriction in females and decrease of sperm motility in males.

Long-term exposure to environmental levels of phenanthrene induces emaciation-thirst disease-like syndromes in female mice

Phenanthrene (Phe) is a polycyclic aromatic hydrocarbon widely present in foods and drinking water. To explore the detrimental effects of Phe on body metabolism, female Kunming mice were treated with Phe in drinking water at concentrations of 0.05, 0.5 and 5 ng/mL. After exposure for 270 d, the animals exhibited dose-dependent reduced body weight and increased water consumption. The dose-dependent accumulation of Phe in the brain decreased hypothalamic neuron numbers, upregulated hypothalamic expression of anaplastic lymphoma kinase, elevated norepinephrine levels in white adipose tissue (WAT) and further activated lipolysis in WAT, leading to a reduction in fat mass. Brown adipose tissue formation was reduced, accompanied by the inhibition of the bone morphogenetic protein signaling pathway. A simultaneous reduced serum levels of antidiuretic hormone (arginine vasopressin) might be one of the reasons for increased water consumption. The present results indicate an environmental etiology and prevention way for the development of emaciation-thirst disease.

Investigation of obesogenic effects of hexachlorobenzene, DDT and DDE in male rats

Obesity has become a very important public health problem and is increasing globally. Genetics, individual and environmental factors play roles in the etiology of this complex disorder. Recently, several environmental pollutants have been suggested to have obesogenic activities. Peroxisome proliferator activating receptor gamma (PPARγ), uncoupling protein-1 (UCP1) and their expression in white adipose tissue (WAT) and brown adipose tissue (BAT) play key roles in adipogenesis. UCP3 and irisin were reported to play roles in non-shivering thermogenesis. Our primary aim was to investigate obesogenic effects of hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) in rats. In addition, thermoregulatory effects of HCB, DDT and DDE were also investigated by analyzing the levels of Ucp3 and irisin. Thirty-two adult male Sprague-Dawley rats were randomly divided into four groups as control, HCB, DDT and DDE. Animals were administered with organochlorine pesticides (OCPs; 5 mg/kg bw) by oral gavage every other day for five weeks. At the end of the experimental period, the animals were sacrificed, BAT and WAT samples were collected to analyze Pparγ, Ucp1 and Ucp3 levels. Moreover, skeletal muscle samples were collected to examine Ucp3 and irisin levels. Serum glucose, cholesterol and triglyceride levels were also determined. Body weight and core temperature of the animals were not significantly affected by any of the OCP administration. Serum glucose, cholesterol and triglyceride levels were similar among the experimental groups. Pparγ expression was significantly elevated by HCB administration only in WAT (p < 0.05). On the other hand, both Pparγ and Ucp1 expressions were diminished in WAT and BAT (p < 0.01) by DDT treatment, while in WAT, DDE significantly decreased Pparγ expression without altering its expression in BAT (p < 0.001). Ucp3 and irisin levels in skeletal muscle were not altered. Our findings show that both DDT and DDE reduce the browning of WAT by suppressing white adipocytes and thus may have obesogenic activity in male rats without altering thermoregulation. In addition, HCB, DDT and DDE-induced alterations in expression of Pparγ and Ucp1 in WAT implicates differential regulation of adipogenic processes.

Obesity II: Establishing causal links between chemical exposures and obesity

Obesity is a multifactorial disease with both genetic and environmental components. The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. We describe another environmental element that can alter the balance between energy intake and energy expenditure: obesogens. Obesogens are a subset of environmental chemicals that act as endocrine disruptors affecting metabolic endpoints. The obesogen hypothesis posits that exposure to endocrine disruptors and other chemicals can alter the development and function of the adipose tissue, liver, pancreas, gastrointestinal tract, and brain, thus changing the set point for control of metabolism. Obesogens can determine how much food is needed to maintain homeostasis and thereby increase the susceptibility to obesity. The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic. Critically, the obesogen hypothesis changes the narrative from curing obesity to preventing obesity.

Type 2 Diabetes Induced by Changes in Proteomic Profiling of Zebrafish Chronically Exposed to a Mixture of Organochlorine Pesticides at Low Concentrations

Effect of organochlorine pesticides (OCPs) mixtures on development of type 2 diabetes mellitus (T2DM) and the underlying mechanism, especially at protein levels, are largely unknown. We exposed a mixture of five OCPs to zebrafish at concentrations of 0, 0.05, 0.25, 2.5, and 25 μg/L for 12 weeks. Differentially expressed proteins (DEPs) were quantitatively identified in female zebrafish livers, and its functional study was conducted. The significantly high glucose and low insulin levels were observed only at 0.05 μg/L, linking to the different pattern of DEPs than other concentrations. A total of 1082 proteins was quantified, of which 321 proteins formed 6 clusters in protein dynamics analysis. The enriched pathways in cluster 3 showing distinct pattern of DEPs could explain the nonlinear response at 0.05 μg/L, indicating that OCP mixtures adversely affected proteins associated with mitochondrial function and energy metabolism. We proposed a feasible mechanism that decrease in expression of aldehyde dehydrogenase led to abnormal accumulation of aldehydes, reducing expression of glyceraldehyde 3-phosphate dehydrogenase, and resulting in disruption of glucose homeostasis. Our findings help to better understand the causality of T2DM by exposure to OCP mixtures and to identify biomarkers in the protein expression level.

Associations of prenatal exposure to mixtures of organochlorine pesticides and smoking and drinking behaviors in adolescence

It is important to identify the factors that influence the prevalence of disinhibitory behaviors, as tobacco and alcohol use in adolescence is a strong predictor of continued use and substance abuse into adulthood. Organochlorine pesticides (OCPs) are persistent organic pollutants that pose a potential risk to the developing fetus and offspring long-term health. We examined associations between prenatal exposure OCPs and their metabolites (i.e., p,p'-DDT, p,p'-DDE, o,p'-DDT, oxychlordane, and hexachlorobenzene (HCB)), both as a mixture and single compounds, and alcohol consumption and smoking at adolescence in a sample (n = 554) from the Child Health and Development Studies prospective birth cohort. Bayesian Kernel Machine Regression demonstrated a trend of higher risk of alcohol use and smoking with higher quartile mixture levels. Single-component analysis showed increased odds of smoking and drinking with increases in lipid-adjusted p,p'-DDE serum levels (aOR = 2.06, 95% CI 0.99-4.31, p = 0.05, per natural log unit increase). We found significant effect modification in these associations by sex with higher p,p'-DDT serum levels (aOR = 0.26, 95% CI 0.09-0.076, p = 0.01, per natural log unit increase) was associated with lower odds of smoking and drinking in female adolescents, while higher p,p'-DDE serum levels (aOR = 2.98, 95% CI 1.04-8.51, p = 0.04, per natural log unit increase) was associated with higher odds of the outcomes. Results of the mutually adjusted model were not significant for male adolescents. Further research to understand reasons for these sex-differences are warranted.

Developmental Exposure to Endocrine Disrupting Chemicals and Its Impact on Cardio-Metabolic-Renal Health

Developmental origin of health and disease postulates that the footprints of early life exposure are followed as an endowment of risk for adult diseases. Epidemiological and experimental evidence suggest that an adverse fetal environment can affect the health of offspring throughout their lifetime. Exposure to endocrine disrupting chemicals (EDCs) during fetal development can affect the hormone system homeostasis, resulting in a broad spectrum of adverse health outcomes. In the present review, we have described the effect of prenatal EDCs exposure on cardio-metabolic-renal health, using the available epidemiological and experimental evidence. We also discuss the potential mechanisms of their action, which include epigenetic changes, hormonal imprinting, loss of energy homeostasis, and metabolic perturbations. The effect of prenatal EDCs exposure on cardio-metabolic-renal health, which is a complex condition of an altered biological landscape, can be further examined in the case of other environmental stressors with a similar mode of action.

Emerging concepts and opportunities for endocrine disruptor screening of the non-EATS modalities

Endocrine disrupting chemicals (EDCs) are ubiquitous in the environment and involve diverse chemical-receptor interactions that can perturb hormone signaling. The Organization for Economic Co-operation and Development has validated several EDC-receptor bioassays to detect endocrine active chemicals and has established guidelines for regulatory testing of EDCs. Focus on testing over the past decade has been initially directed to EATS modalities (estrogen, androgen, thyroid, and steroidogenesis) and validated tests for chemicals that exert effects through non-EATS modalities are less established. Due to recognition that EDCs are vast in their mechanisms of action, novel bioassays are needed to capture the full scope of activity. Here, we highlight the need for validated assays that detect non-EATS modalities and discuss major international efforts underway to develop such tools for regulatory purposes, focusing on non-EATS modalities of high concern (i.e., retinoic acid, aryl hydrocarbon receptor, peroxisome proliferator-activated receptor, and glucocorticoid signaling). Two case studies are presented with strong evidence amongst animals and human studies for non-EATS disruption and associations with wildlife and human disease. This includes metabolic syndrome and insulin signaling (case study 1) and chemicals that impact the cardiovascular system (case study 2). This is relevant as obesity and cardiovascular disease represent two of the most significant health-related crises of our time. Lastly, emerging topics related to EDCs are discussed, including recognition of crosstalk between the EATS and non-EATS axis, complex mixtures containing a variety of EDCs, adverse outcome pathways for chemicals acting through non-EATS mechanisms, and novel models for testing chemicals. Recommendations and considerations for evaluating non-EATS modalities are proposed. Moving forward, improved understanding of the non-EATS modalities will lead to integrated testing strategies that can be used in regulatory bodies to protect environmental, animal, and human health from harmful environmental chemicals.

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.

Prenatal exposure to persistent organic pollutants and childhood obesity: A systematic review and meta-analysis of human studies

We conducted a systematic review and meta-analysis of the associations between prenatal exposure to persistent organic pollutants (POPs) and childhood obesity. We focused on organochlorines (dichlorodiphenyltrichloroethane [DDT], dichlorodiphenyldichloroethylene [DDE], hexachlorobenzene [HCB], and polychlorinated biphenyls [PCBs]), perfluoroalkyl and polyfluoroalkyl substances (PFAS), and polybrominated diphenyl ethers (PBDEs) that are the POPs more widely studied in environmental birth cohorts so far. We search two databases (PubMed and Embase) through July/09/2021 and identified 33 studies reporting associations with prenatal organochlorine exposure, 21 studies reporting associations with prenatal PFAS, and five studies reporting associations with prenatal PBDEs. We conducted a qualitative review. Additionally, we performed random-effects meta-analyses of POP exposures, with data estimates from at least three prospective studies, and BMI-z. Prenatal DDE and HCB levels were associated with higher BMI z-score in childhood (beta: 0.12, 95% CI: 0.03, 0.21; I2 : 28.1% per study-specific log increase of DDE and beta: 0.31, 95% CI: 0.09, 0.53; I2 : 31.9% per study-specific log increase of HCB). No significant associations between PCB-153, PFOA, PFOS, or pentaPBDEs with childhood BMI were found in meta-analyses. In individual studies, there was inconclusive evidence that POP levels were positively associated with other obesity indicators (e.g., waist circumference).

Exposure to the pesticide DDT and risk of diabetes and hypertension: Systematic review and meta-analysis of prospective studies

BACKGROUND

Experimental evidence suggests that p,p'-DDE might be involved in the development of diabetes and hypertension (HTN); however, the evidence in humans is inconclusive.

OBJECTIVE

To summarize the epidemiological evidence for the association of p,p'-DDT exposure and its breakdown products with the risk of diabetes and HTN from prospective studies.

METHODS

We performed a systematic review and meta-analysis based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Eligible studies (prospective) were search in PubMed, Web of Science, EBSCO, and SciELO databases (July 11, 2020). Different search algorithms were used for diabetes and HTN. Pooled odds ratios (ORs) were estimated from meta-analysis with random effects for each exposure and outcome.

RESULTS

A total of 23 prospective studies were included in this review, 16 assessed diabetes and seven HTN; very few measured p,p'-DDT. Exposure to p,p'-DDE was associated with a slightly increased risk of type 2 diabetes (T2D) (pooled OR = 1.44; 95%CI: 1.00, 2.07; p = 0.049) and HTN (pooled OR = 1.21; 95%CI: 1.07, 1.38). Dose-response meta-analysis suggested a non-linear relation between p,p'-DDE and T2D. Exposure to p,p'-DDE was not associated with gestational diabetes (pooled OR = 1.01; 95%CI: 0.94, 1.09); similarly, p,p'-DDT was not associated with T2D (pooled OR = 1.03; 95%CI: 0.79, 1.35).

CONCLUSIONS

Evidence from prospective studies suggests that exposure to p,p'-DDE, the main breakdown product of p,p'-DDT, might increase the risk of developing T2D; such increase may be apparent only at low levels. Exposure to p,p'-DDE may also increase the risk of having HTN; however, further evidence is required.

Type 2 Diabetes Mellitus Mediation by the Disruptive Activity of Environmental Toxicants on Sex Hormone Receptors: In Silico Evaluation

This study investigates the disruptive activity of environmental toxicants on sex hormone receptors mediating type 2 diabetes mellitus (T2DM). Toxicokinetics, gene target prediction, molecular docking, molecular dynamics, and gene network analysis were applied in silico techniques. From the results, permethrin, perfluorooctanoic acid, dichlorodiphenyltrichloroethane, O-phenylphenol, bisphenol A, and diethylstilbestrol were the active toxic compounds that could modulate androgen (AR) and estrogen-α and -β receptors (ER) to induce T2DM. Early growth response 1 (EGR1), estrogen receptor 1 (ESR1), and tumour protein 63 (TP63) were the major transcription factors, while mitogen-activated protein kinases (MAPK) and cyclin-dependent kinases (CDK) were the major kinases upregulated by these toxicants via interactions with intermediary proteins such as PTEN, AKT1, NfKβ1, SMAD3 and others in the gene network analysis to mediate T2DM. These toxicants pose a major challenge to public health; hence, monitoring their manufacture, use, and disposal should be enforced. This would ensure reduced interaction between people and these toxic chemicals, thereby reducing the incidence and prevalence of T2DM.

Decreased secondary faecal bile acids in children with ulcerative colitis and Clostridioides difficile infection

BACKGROUND

Patients with ulcerative colitis (UC) have an increased risk of Clostridioides difficile infection (CDI). There is a well-documented relationship between bile acids and CDI.

AIMS

To evaluate faecal bile acid profiles and gut microbial changes associated with CDI in children with UC.

METHODS

This study was conducted at Children's Hospital Los Angeles. Faecal bile acids and gut microbial genes related to bile acid metabolism were measured in 29 healthy children, 23 children with mild to moderate UC without prior CDI (UC group), 16 children with mild to moderate UC with prior CDI (UC+CDI group) and 10 children without UC with prior CDI (CDI group).

RESULTS

Secondary faecal bile acids, especially lithocholic acid (3.296 vs 10.793, P ≤ 0.001) and ursodeoxycholic acid (7.414 vs 10.617, P ≤ 0.0001), were significantly lower in children with UC+CDI when compared to UC alone. Secondary faecal bile acids can predict disease status between these groups with 84.6% accuracy. Additionally, gut microbial genes coding for bile salt hydrolase, 7α-hydroxysteroid dehydrogenase and 7α/β-dehydroxylation were all diminished in children with UC+CDI compared to children with UC alone.

CONCLUSIONS

Bile acids can distinguish between children with UC based on their prior CDI status. Bile acid profile changes can be explained by gut microbial genes encoding for bile salt hydrolase, 7α-hydroxysteroid dehydrogenase and 7α/β-dehydroxylation. Bile acid profiles may be helpful as biomarkers to identify UC children who have had CDI and may serve as future therapeutic targets.

The pesticide chlorpyrifos promotes obesity by inhibiting diet-induced thermogenesis in brown adipose tissue

Obesity results from a caloric imbalance between energy intake, absorption and expenditure. In both rodents and humans, diet-induced thermogenesis contributes to energy expenditure and involves the activation of brown adipose tissue (BAT). We hypothesize that environmental toxicants commonly used as food additives or pesticides might reduce BAT thermogenesis through suppression of uncoupling protein 1 (UCP1) and this may contribute to the development of obesity. Using a step-wise screening approach, we discover that the organophosphate insecticide chlorpyrifos suppresses UCP1 and mitochondrial respiration in BAT at concentrations as low as 1 pM. In mice housed at thermoneutrality and fed a high-fat diet, chlorpyrifos impairs BAT mitochondrial function and diet-induced thermogenesis, promoting greater obesity, non-alcoholic fatty liver disease (NAFLD) and insulin resistance. This is associated with reductions in cAMP; activation of p38MAPK and AMPK; protein kinases critical for maintaining UCP1 and mitophagy, respectively in BAT. These data indicate that the commonly used pesticide chlorpyrifos, suppresses diet-induced thermogenesis and the activation of BAT, suggesting its use may contribute to the obesity epidemic.

Nonmonotonic response of type 2 diabetes by low concentration organochlorine pesticide mixture: Findings from multi-omics in zebrafish

Exposure to a single organochlorine pesticide (OCP) at high concentration and over a short period of exposure constrain our understanding of the contribution of chemical exposure to type 2 diabetes (T2D). A total of 450 male and female zebrafish was exposed to mixtures of five OCPs at 0, 0.05, 0.25, 2.5, and 25 μg/L for 12 weeks. T2D-related hematological parameters (i.e., glucose, insulin, free fatty acid, and triglycerides) and mitochondrial complex I to IV activities were assessed. Metabolomics, proteomics, and transcriptomics were analyzed in female livers, and their data-driven integration was performed. High fasting glucose and low insulin levels were observed only at 0.05 μg/L of the OCP mixture in females, indicating a nonlinear and sexually dependent response. We found that exposure to the OCP mixture inhibited the activities of mitochondrial complexes, especially III and IV. Combining individual and integrated omics analysis, T2D-linked metabolic pathways that regulate mitochondrial function, insulin signaling, and energy homeostasis were altered by the OCP mixture, which explains the observed phenotypic hematological effects. We demonstrated the cause-and-effect relationship between exposures to OCP mixture and T2D using zebrafish model. This study gives an insight into mechanistic research of metabolic diseases caused by chemical exposure using zebrafish.

Neurotensin differentially regulates bile acid metabolism and intestinal FXR-bile acid transporter axis in response to nutrient abundance

Studies demonstrate a role for neurotensin (NT) in obesity and related comorbidities. Bile acid (BA) homeostasis alterations are associated with obesity. We determined the effect of NT on BA metabolism in obese and non-obese conditions. Plasma and fecal BA profiles were analyzed by LC-MS/MS in male and female NT^+/+ and NT^-/- mice fed low-fat (LFD) or high-fat diet (HFD) for 6 weeks (early stage of obesity) or greater than 20 weeks (late stage of obesity). The nuclear farnesoid X receptor (FXR) and BA transporter mRNA expression were assessed in ileum, mouse enteroids, and human cell lines. HFD decreased plasma primary and secondary BAs in NT^+/+ mice; HFD-induced decrease of plasma BAs was improved in NT-deficient mice. In NT^+/+ mice, HFD inhibited ileal FXR and BA transporter expression; HFD-decreased expression of FXR and BA transporters was prevented in NT^-/- mice. Compared with LFD-fed NT^+/+ mice, LFD-fed NT^-/- mice had relatively lower levels of ileal FXR and BA transporter expression. Moreover, NT stimulates the expression of FXR and BA transporters in Caco-2 cells; however, stimulated expression of BA transporters was attenuated in NT^-/- enteroids. Therefore, we demonstrate that HFD disrupts the BA metabolism and ileal FXR and BA transporter axis which are improved in the absence of NT, suggesting that NT contributes to HFD-induced disruption of BA metabolism and plays an inhibitory role in the regulation of ileal FXR and BA transporter signaling under obese conditions. Conversely, NT positively regulates the expression of ileal FXR and BA transporters under non-obese conditions. Therefore, NT plays a dual role in obese and non-obese conditions, suggesting possible therapeutic strategies for obesity control.