Promoting differentiation and lipid metabolism are the primary effects for DINP exposure on 3T3-L1 preadipocytes

Comparative analysis of diisononyl phthalate and di(isononyl)cyclohexane-1,2 dicarboxylate plasticizers in regulation of lipid metabolism in 3T3-L1 cells

Diisononyl phthalate (DINP) and di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) are plasticizers introduced to replace previously used phthalate plasticizers in polymeric products. Exposure to DINP and DINCH has been shown to impact lipid metabolism. However, there are limited studies that address the mechanisms of toxicity of these two plasticizers. Here, a comparative toxicity analysis has been performed to evaluate the impacts of DINP and DINCH on 3T3-L1 cells. The preadipocyte 3T3-L1 cells were exposed to 1, 10, and 100 μM of DINP or DINCH for 10 days and assessed for lipid accumulation, gene expression, and protein analysis. Lipid staining showed that higher concentrations of DINP and DINCH can induce adipogenesis. The gene expression analysis demonstrated that both DINP and DINCH could alter the expression of lipid-related genes involved in adipogenesis. DINP and DINCH upregulated Pparγ, Pparα, C/EBPα Fabp4, and Fabp5, while both compounds significantly downregulated Fasn and Gata2. Protein analysis showed that both DINP and DINCH repressed the expression of FASN. Additionally, we analyzed an independent transcriptome dataset encompassing temporal data on lipid differentiation within 3T3-L1 cells. Subsequently, we derived a gene set that accurately portrays significant pathways involved in lipid differentiation, which we subsequently subjected to experimental validation through quantitative polymerase chain reaction. In addition, we extended our analysis to encompass a thorough assessment of the expression profiles of this identical gene set across 40 discrete transcriptome datasets that have linked to diverse pathological conditions to foreseen any potential association with DINP and DINCH exposure. Comparative analysis indicated that DINP could be more effective in regulating lipid metabolism.

Non-monotonic dose-response of di-(2-ethylhexyl) phthalate isolated from Penicillium citrinum XT6 on adipogenesis and expression of PPARγ and GLUT4 in 3T3-L1 adipocytes

OBJECTIVES

Adipogenesis is the fat cell formation process regulated by peroxisome proliferator-activated receptors (PPARγ). The insulin-responsive glucose transporter 4 (GLUT4) has a major role in glucose uptake and metabolism in insulin target tissues (i.e., adipose and muscle cells). The interplay between PPARγ and GLUT4 is essential for proper glucose homeostasis. This study aimed to isolate, elucidate, and investigate the effect of an isolated compound from Penicillium citrinum XT6 on adipogenesis, PPARγ, and GLUT4 expression in 3T3-L1 adipocytes.

METHODS

The isolated compound was determined by analyzing spectroscopic data (LC-MS, FT-IR, Spectrophotometry UV-Vis, and NMR). The adipogenesis activity of the isolated compound in 3T3-L1 cells was determined by the Oil Red O staining method. RT-PCR was used to analyze the gene expression of PPARγ and GLUT4.

RESULTS

Di-(2-ethylhexyl)-phthalate (DEHP) was the isolated compound from P.citrinum XT6. The results revealed adipogenesis stimulation and inhibition, as well as PPARγ and GLUT4 expressions.

CONCLUSIONS

DEHP showed a non-monotonic dose-response (NMDR) effect on adipogenesis and PPARγ and GLUT4 expression. It is the first study that reveals DEHP's NMDR effects on lipid and glucose metabolism in adipocytes.

Chronic exposure to a mixture of phthalates shifts the white and brown adipose tissue phenotypes in female mice

Phthalates are endocrine-disrupting chemicals used in consumer products. Although phthalates are obesogens and affect metabolic function, it is unknown if chronic exposure for 6 months to a phthalate mixture alters adipose tissue phenotype in female mice. After vehicle or mixture exposure, white adipose tissue and brown adipose tissue (WAT and BAT) were analyzed for expression of adipogenesis, proliferation, angiogenesis, apoptosis, oxidative stress, inflammation, and collagen deposition markers. The mixture altered WAT morphology, leading to an increase in hyperplasia, blood vessel number, and expression of BAT markers (Adipoq and Fgf2) in WAT. The mixture increased the expression of the inflammatory markers, Il1β, Ccl2, and Ccl5, in WAT. The mixture also increased expression of the proapoptotic (Bax and Bcl2) and antiapoptotic (Bcl2l10) factors in WAT. The mixture increased expression of the antioxidant Gpx1 in WAT. The mixture changed BAT morphology by increasing adipocyte diameter, whitening area, and blood vessel number and decreased expression of the thermogenic markers Ucp1, Pgargc1a, and Adrb3. Furthermore, the mixture increased the expression of adipogenic markers Plin1 and Cebpa, increased mast cell number, and increased Il1β expression in BAT. The mixture also increased expression of the antioxidant markers Gpx and Nrf2 and the apoptotic marker Casp2 in BAT. Collectively, these data indicate that chronic exposure to a phthalate mixture alters WAT and BAT lipid metabolism phenotypes in female mice, leading to an apparent shift in their normal morphology. Following long-term exposure to a phthalate mixture, WAT presented BAT-like features and BAT presented WAT-like features.

Di-(2-ethylhexyl) phthalate (DEHP) promoted hepatic lipid accumulation by activating Notch signaling pathway

Di-(2-ethylhexyl) phthalate (DEHP) and mono-2-ethylhexyl phthalate (MEHP) can induce hepatic lipid metabolism disorders, while the molecular mechanism still remain unknown. We aim to explore the underlying mechanism of Notch signaling pathway on hepatic lipid accumulation induced by DEHP/MEHP. A total of 40 male wistar rats were exposed to DEHP (0, 5, 50, and 500 mg/kg/d) for 8 weeks, BRL-3A hepatocytes were exposed to MEHP (0, 10, 50, 100, and 200 μM) for 24 h. About 50 μM DAPT and 100 μg/mL Aspirin were used to inhibit Notch pathway and prevent inflammation, respectively. Real-Time PCR was performed to detect the mRNA expression, western blot and immunofluorescence were used to detect the protein expression. Lipids and inflammatory factors levels were determined by commercial kits. The results showed that DEHP/MEHP promoted the expression of Notch pathway molecules and lipids accumulation in rat livers/BRL-3A cells. The up-regulated Notch receptors were correlated with the TG levels in the rat liver. MEHP increased the levels of IL-8 and IL-1β. The lipids levels were reduced after anti-inflammation. The inhibition of Notch pathway reversed the elevation of inflammation and lipid accumulation caused by MEHP. In conclusion, this study demonstrated that DEHP/MEHP led to lipid accumulation in hepatocytes by up-regulating Notch pathway and the inflammation might play a key role in the process.

Downregulation of miRNA-155-5p contributes to the adipogenic activity of 2-ethylhexyl diphenyl phosphate in 3T3-L1 preadipocytes

2-Ethylhexyl diphenyl phosphate (EHDPP) is a commonly used organophosphorus flame retardant and food packaging material. Because of its high lipophilic and bioaccumulative properties, adipocytes are the primary target of EHDPP. However, the toxicity of EHDPP on preadipocytes and the potential mechanism have not been fully elucidated. MicroRNAs (miRNAs) are thought to be an important mediator that contribute to the toxicity of environmental contaminants. To identify the miRNAs specifically responsible for EHDPP exposure and their role in EGDPP's toxicity in preadipocytes, the adipogenic effects and miRNA expression profiling were performed on 3T3-L1 preadipocytes exposed to EHDPP. EHDPP at concentrations of 1-10 μM promoted adipocyte differentiation, as evidenced by lipid staining, triglyceride content, and expression of adipogenesis markers. MiRNA-seq analysis revealed that 7 differentially expressed miRNAs were recognized under EHDPP exposure, with miR-155-5p being the top down-regulated miRNA. Quantitative reverse transcription PCR (RT-qPCR) analysis showed that miR-155-5p level fell sharply during the first 2 days and continued to fall dose-dependently throughout the EHDPP exposure period. MiR-155-5p inhibition promotes adipocyte differentiation, whereas its overexpression counteracted EHDPP-induced adipogenesis. Luciferase reporter assay identified CCAAT/enhancer-binding protein beta (C/EBPβ) as a target of miR-155-5p in 3T3-L1 preadipocytes in response to EHDPP. Taken together, EHDPP exposure down-regulated miR-155-5p, which then increased C/EBPβ and peroxisome proliferator-activated receptor γ (PPARγ) expression and promoted adipogenesis in preadipocytes.

Triphenyl phosphate proved more potent than its metabolite diphenyl phosphate in inducing hepatic insulin resistance through endoplasmic reticulum stress

Triphenyl phosphate (TPHP) is a widely used flame retardant and plasticizer and has been detected extensively in environmental media, wildlife and human bodies. Several epidemiological and animal studies have revealed that TPHP exposure is positively associated with glucose homeostasis disruption and diabetes. However, the effects of TPHP on hepatic glucose homeostasis and the underlying mechanisms remain unclear. The present work aimed to investigate the cytotoxicity and glucose metabolism disruption of TPHP and its metabolite diphenyl phosphate (DPHP) within hepatocytes. The cell viability assay undertaken on human normal liver (L02) cells showed that TPHP exhibited more potent hepatotoxicity than DPHP. RNA sequencing (RNA-seq) data showed that TPHP and DPHP presented different modes of toxic action. Insulin resistance is one of the predominant toxicities for TPHP, but not for DPHP. The insulin-stimulated glucose uptake and glycogen synthesis were impaired by TPHP, while DPHP exhibited no significant impairment on these factors. TPHP exposure induced endoplasmic reticulum (ER) stress, and the ER stress antagonist 4-PBA restored the impairment of insulin-stimulated glucose uptake and glycogen synthesis induced by TPHP. TPHP could also induce liver ER stress and insulin resistance in mice. Taken together, the results suggested that TPHP induces more potent insulin resistance through ER stress than its metabolite DPHP.

Di-isononyl phthalate induces apoptosis and autophagy of mouse ovarian granulosa cells via oxidative stress

Di-isononyl phthalate (DINP) has been widely utilized in industrial, commercial and medical applications for the past few years. Therefore, more attention should be paid to the toxicity of DINP. DINP can cause damage to female reproductive system; however, the potential mechanism remains to be further investigated. In this study, female mice were orally administered with 0, 2, 20 and 200 mg DINP/kg/day for 14 days. We found that DINP significantly affected the arrangement of granulosa cells in ovarian follicles. In addition, DINP could induce apoptosis, autophagy and oxidative stress of the ovary tissue. Meanwhile, the serum estradiol concentration distinctly decreased in the 20 and 200 mg/kg DINP-treated groups, suggesting that DINP might affect the function of ovarian granulosa cells. Primary mouse ovarian granulosa cells were utilized for further investigation after the cells were treated with 0, 100, 200, 400 μM DINP for 24 h. Similar to the in vivo experiment, DINP could also induce apoptosis and autophagy of ovarian granulosa cells, as well as oxidative stress; while inhibition of oxidative stress by NAC could alleviate DINP-induced apoptosis and autophagy. Furthermore, inhibition of autophagy by 3-MA could also rescue the induction of apoptosis by DINP. Taken together, these results indicated that DINP induced apoptosis and autophagy of mouse ovarian granulosa cells via oxidative stress, and autophagy played a cytotoxic role in DINP-induced apoptosis.

Effects of DEHP, DEHT and DINP Alone or in a Mixture on Cell Viability and Mitochondrial Metabolism of Endothelial Cells In Vitro

Plasticizers are chemicals in high demand, used in a wide range of commercial products. Human are exposed through multiple pathways, from numerous sources, to multiple plasticizers. This is a matter of concern, as it may contribute to adverse health effects. The vascular system carries plasticizers throughout the body and therefore can interact with the endothelium. The aim of the study was to evaluate the in vitro toxicity on endothelial cells by considering the individual and the mixture effects of bis-(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP) or bis-(2-ethylhexyl) terephthalate (DEHT). In this study, their cytotoxicity on HMEC-1 cells was evaluated on cell function (viability, cell counting, total glutathione and intracellular adenosines) and mitochondrial function (mitochondrial respiration). Results showed cellular physiological perturbations induced with all the condition tested, excepted for DEHT. Plasticizers induced a cytotoxicity by targeting mitochondrial respiration, depleting mitochondrial ATP production and increasing glycolytic metabolism. Additionally, delayed effects were observed between the cellular and the mitochondrial parameters. These results suggest that endothelial cells could go through a metabolic adaptation to face plasticizer-induced cellular stress, to effectively maintain their cellular processes. This study provides additional information on the adverse effects of plasticizers on endothelial cells.

Andrographolide in Atherosclerosis: Integrating Network Pharmacology and In Vitro Pharmacological Evaluation

Objective: Andrographis paniculata (Burm.f.) Nees is a medicinal plant that has been traditionally used as an anti-inflammatory and antibacterial remedy for several conditions. Andrographolide (AG), the active constituent of A. paniculata (Burm.f.) Nees, has anti-lipidic and anti-inflammatory properties as well as cardiovascular protective effects. The present study aimed to explore the effects of AG on the progression of atherosclerosis and to investigate related mechanisms via network pharmacology.

Materials and methods: Compound-related information was obtained from the PubChem database. Potential target genes were identified using STITCH, SwissTargetPrediction, Bioinformatics Analysis Tool for Molecular mechANism of Traditional Chinese Medicine, and Comparative Toxicogenomics Database. Genes involved in atherosclerosis were obtained from DisGeNet and compared with AG target genes to obtain an overlapping set. Protein–protein interactions were determined by STRING. Gene ontology (GO) analysis was performed at WebGestalt, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment was analyzed using Metascape. The final network showing the relationship between compounds, targets, and pathways was constructed using Cytoscape. After that, oxLDL-induced RAW264.7 cells were used to further validate a part of the network pharmacology results.

Result: Eighty-one potential AG target genes were identified. PPI, GO, and KEGG enrichment revealed genes closely related to tumor progression, lipid transport, inflammation, and related pathways. AG improves the reverse cholesterol transport (RCT) through NF-κB/CEBPB/PPARG signaling in oxLDL-induced RAW264.7 cells.

Conclusion: We successfully predict AG’s potential targets and pathways in atherosclerosis and illustrate the mechanism of action. AG may regulate NF-κB/CEBPB/PPARG signaling to alleviate atherosclerosis.

Obesogens in Foods

Obesogens, as environmental endocrine-disrupting chemicals, are supposed to have had an impact on the prevalence of rising obesity around the world over the last forty years. These chemicals are probably able to contribute not only to the development of obesity and metabolic disturbances in individuals, but also in their progeny, having the capability to epigenetically reprogram genetically inherited set-up points for body weight and body composition control during critical periods of development, such as fetal, early life, and puberty. In individuals, they may act on myriads of neuro-endocrine–immune metabolic regulatory pathways, leading to pathophysiological consequences in adipogenesis, lipogenesis, lipolysis, immunity, the influencing of central appetite and energy expenditure regulations, changes in gut microbiota–intestine functioning, and many other processes. Evidence-based medical data have recently brought much more convincing data about associations of particular chemicals and the probability of the raised risk of developing obesity. Foods are the main source of obesogens. Some obesogens occur naturally in food, but most are environmental chemicals, entering food as a foreign substance, whether in the form of contaminants or additives, and they are used in a large amount in highly processed food. This review article contributes to a better overview of obesogens, their occurrence in foods, and their impact on the human organism.

Prenatal maternal phthalate exposures and trajectories of childhood adiposity from four to twelve years

BACKGROUND/AIM

Adiposity trajectories reflect dynamic process of growth and may predict later life health better than individual measures. Prenatal phthalate exposures may program later childhood adiposity, but findings from studies examining these associations are conflicting. We investigated associations between phthalate biomarker concentrations during pregnancy with child adiposity trajectories.

METHODS

We followed 514 mother-child pairs from the Mexico City PROGRESS cohort from pregnancy through twelve years. We measured concentrations of nine phthalate biomarkers in 2nd and 3rd trimester maternal urine samples to create a pregnancy average using the geometric mean. We measured child BMI z-score, fat mass index (FMI), and waist-to-height ratio (WHtR) at three study visits between four and 12 years of age. We identified adiposity trajectories using multivariate latent class growth modeling, considering BMI z-score, FMI, and WHtR as joint indicators of latent adiposity. We estimated associations of phthalates biomarkers with class membership using multinomial logistic regression. We used quantile g-computation to estimate the potential effect of the total phthalate mixture and assessed effect modification by sex.

RESULTS

We identified three trajectories of child adiposity, a "low-stable", a "low-high", and a "high-high" group. A doubling of the sum of di (2-ethylhexyl) phthalate metabolites (ΣDEHP), was associated with 1.53 (1.08, 2.19) greater odds of being in the "high-high" trajectory in comparison to the "low-stable" group, whereas a doubling in di-isononyl phthalate metabolites (ΣDiNP) was associated with 1.43 (1.02, 2.02) greater odds of being in the "low-high" trajectory and mono (carboxy-isononyl) phthalate (MCNP) was associated with 0.66 (0.45, 97) lower odds of being in the "low-high" trajectory. No sex-specific associations or mixture associations were observed.

CONCLUSIONS

Prenatal concentrations of urinary DEHP metabolites, DiNP metabolites, and MCNP, a di-isodecyl phthalate metabolite, were associated with trajectories of child adiposity. The total phthalate mixture was not associated with early life child adiposity.

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.

Embryotoxic effects of tribromophenol on early post-implantation development of mouse embryos in vitro

2,4,6-Tribromophenol (TBP, CAS No. 118-79-6), the most widely produced brominated phenol, is frequently detected in environmental components. The detection of TBP in human bodies has earned great concerns about its adverse effects on human beings, especially for early embryonic development. Here, we optimized the mouse embryo in vitro culture (IVC) system for early post-implantation embryos and employed it to determine the embryotoxicity of TBP. With this new research model, we revealed the dose-dependent toxic effects of TBP on mouse embryos from peri-implantation to egg cylinder stages. Furthermore, TBP exposure inhibited the differentiation and survival of epiblast (EPI) cells and extraembryonic endoderm (ExEn) cells, while those of extraembryonic ectoderm (ExEc) cells were not influenced. These results implied that TBP might inhibit embryonic development by influencing the generation of three primary germ layers and fetal membranes (the amnion, chorionic disk, umbilical cord, and yolk sac). In summary, we showed a proof of concept for applying mouse embryo IVC system as a novel research model for studying mammalian embryonic toxicology of environmental pollutants. This study also demonstrated the toxicity of TBP on early embryonic development of mammals.

Chemokine (C-C motif) ligand 2-enhanced adipogenesis and angiogenesis of human adipose-derived stem cell and human umbilical vein endothelial cell co-culture system in adipose tissue engineering

Human adipose-derived stem cells (hADSCs) and human umbilical vein endothelial cells (HUVECs) co-cultured in vitro are widely used in adipose tissue engineering but exhibit various limitations. Chemokine (C-C motif) ligand 2 (CCL2) has been proved essential during adipogenesis and angiogenesis in vivo. We examined whether adipogenesis and angiogenesis could also be directly promoted by CCL2 in vitro. Cells were cultured with 0, 10, 50, and 100 ng/ml CCL2. The effects of CCL2 on adipogenesis of hADSCs, and lipid accumulation in the positive control group (hADSCs), blank control group (hADSCs + HUVECs), and experimental group (hADSCs + HUVECs + CCL2) in the hADSC and HUVEC direct co-culture system were evaluated by Oil Red O staining. Angiogenesis in the presence of CCL2 was evaluated by Matrigel tube formation assay. Angiogenic- and adipogenic-associated gene and protein expression in the co-culture system were measured by Quantitative Real-time Polymerase Chain Reaction and western blotting, respectively. All concentrations of CCL2 promoted hADSC adipogenic differentiation and HUVEC tube formation (P < 0.05). Following direct co-culture, the experimental group accumulated more lipid droplets than the positive control (P < 0.0001), whereas the latter showed better adipogenesis than the blank control group. 50 ng/ml CCL2 exhibited stronger adipogenic and angiogenic potential than other concentrations. After 72 h of direct co-culture, the mRNA expression of adipogenic differentiation (peroxisome proliferators-activated receptorsγ, CCAAT/enhancer binding protein-α, Leptin, and lipoprotein lipase) and angiogenic genes (vascular endothelial growth factor-A, vascular endothelial growth factor receptor 2, matrix metalloprotein (MMP) 9, and 14) in the experimental group was much higher than in the control (P < 0.05). The addition of 50 ng/ml CCL2 in the system resulted in elevated phosphorylated Protein kinase B/AKT expression. In summary, CCL2 directly promoted adipogenesis of hADSCs and angiogenesis of HUVECs under both mono-culture and co-culture condition in vitro possibly by enhancing AKT phosphorylation. An optimal concentration of 50 ng/ml CCL2 could improve the adipogenesis and angiogenesis of hADSC and HUVEC co-culture system.

Phthalates and Alternative Plasticizers Differentially affect Phenotypic Parameters in Gonadal Somatic and Germ Cell Lines

The developmental and reproductive toxicity associated with exposure to phthalates has motivated a search for alternatives. However, there is limited knowledge regarding the adverse effects of some of these chemicals. We used high-content imaging to compare the effects of mono (2-ethylhexyl) phthalate (MEHP) with six alternative plasticizers: di-2-ethylhexyl terephthalate (DEHTP); diisononyl-phthalate (DINP); di-isononylcyclohexane-1,2-dicarboxylate (DINCH); 2-ethylhexyl adipate (DEHA); 2,2,4-trimethyl 1,3-pentanediol diisobutyrate (TXIB) and di-iso-decyl-adipate (DIDA). A male germ spermatogonial cell line (C18-4), a Sertoli cell line (TM4) and two steroidogenic cell lines (MA-10 Leydig and KGN granulosa) were exposed for 48h to each chemical (0.001-100 μM). Cell images were analyzed to assess cytotoxicity and effects on phenotypic endpoints. Only MEHP (100 μM) was cytotoxic and only in C18-4 cells. However, several plasticizers had distinct phenotypic effects in all four cell lines. DINP increased Calcein intensity in C18-4 cells, whereas DIDA induced oxidative stress. In TM4 cells, MEHP, and DINCH affected lipid droplet numbers, while DEHTP and DINCH increased oxidative stress. In MA-10 cells, MEHP increased lipid droplet areas and oxidative stress; DINP decreased the number of lysosomes, while DINP, DEHA and DIDA altered mitochondrial activity. In KGN cells, MEHP, DINP and DINCH increased the number of lipid droplets, whereas DINP decreased the number of lysosomes, increased oxidative stress and affected mitochondria. The Toxicological Priority Index (ToxPi) provided a visual illustration of the cell line specificity of the effects on phenotypic parameters. The lowest administered equivalent doses were observed for MEHP. We propose that this approach may assist in screening alternative plasticizers.

Di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH) alters transcriptional profiles, lipid metabolism and behavior in zebrafish larvae

Plasticizers are commonly used in different consumer goods and personal care products to provide flexibility, durability and elasticity to polymers. Due to their reported toxicity, the use of several plasticizers, including phthalates has been regulated and/or banned from the market. Di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH) is an alternative plasticizer that was introduced to replace toxic plasticizers. Increasing global demand and lack of toxicity data and safety assessment of DINCH have raised the concern to human and animal health. Hence, in the present study, we investigated the adverse effects of DINCH (at concentrations ranging from 0.01 to 10 μM) in early developmental stages of zebrafish using different endpoints such as hatching rate, developmental abnormalities, lipid content, behavior analysis and gene expression. We found that DINCH caused hatching delay in a dose-dependent manner and altered the expression of genes involved in stress response. Lipid staining using Oil Red O stain showed a slight lipid accumulation around the yolk, brain, eye and neck with increasing concentration. Genes associated with lipid transport such as fatty acid synthesis, β-oxidation, elongation, lipid transport were significantly altered by DINCH. Genes involved in cholesterol biosynthesis and homeostasis were also affected by DINCH indicating possible developmental neurotoxicity. Behavioral analysis of larvae demonstrated a distinct locomotor activity upon exposure to DINCH. The present data shows that DINCH could induce physiological and metabolic toxicity to aquatic organisms. Hence, further analyses and environmental monitoring of DINCH should be conducted to determine its safety and toxicity levels.

Exposure to endocrine-disrupting compounds such as phthalates and bisphenol A is associated with an increased risk for obesity

Increasing evidence from epidemiological, animal and in vitro studies suggests that the increased production of synthetic chemicals that interfere with the proper functioning of the hormonal system, so-called endocrine-disrupting compounds (EDCs), might be involved in the development and rapid spread of obesity, coined the obesity epidemic. Recent findings have demonstrated that EDCs may interfere with hormonal receptors that regulate adipogenesis and metabolic pathways. Furthermore, prenatal exposure to EDCs has been shown to influence the metabolism of the developing embryo through epigenetic mechanisms and to promote obesity in subsequent generations. In this Review, we discuss the potential impact of bisphenol A (BPA) and phthalate-based plasticizers on obesity and obesity-related metabolic disorders. Special emphasis is given to the obesogenic effects of prenatal exposure and strategies for identifying, regulating, and replacing EDCs.

Mechanistic insight into toxicity of phthalates, the involved receptors, and the role of Nrf2, NF-κB, and PI3K/AKT signaling pathways

The wide use of phthalates, as phthalates are used in the manufacturing of not only plastics but also many others goods, has become a main concern in the current century because of their potency to induce deleterious effects on organism health. The toxic effects of phthalates such as reproductive toxicity, cardiotoxicity, hepatotoxicity, nephrotoxicity, teratogenicity, and tumor development have been widely indicated by previous experimental studies. Some of the important mechanisms of toxicity by phthalates are the induction and promotion of inflammation, oxidative stress, and apoptosis. Awareness of the involved molecular pathways of these mechanisms will permit the detection of exact molecular targets of phthalates to protect or treat their toxicity. Up to now, various transcription factors and signaling pathways have been associated with phthalate-induced toxicity which by influencing on nuclear surface and the expression of different genes can alter cell hemostasis. In different studies, the role of nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor-κB (NF-κB), and phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathways in processes of oxidative stress, inflammation, apoptosis, and cancer has been shown following exposure to phthalates. In the present review, we aim to survey experimental studies (in vitro and in vivo) in order to show firstly the most involved receptors and also the importance and the role of the mentioned signaling pathways in phthalate-induced toxicity, and with considering this point, the future studies can focus on these molecular targets as a strategic method to reduce environmental chemicals-induced toxicity especially phthalates toxic effects.

Augmentation of RBP4/STRA6 signaling leads to insulin resistance and inflammation and the plausible therapeutic role of vildagliptin and metformin

A role of Retinol Binding Protein-4 (RBP4) in insulin resistance is widely studied. However, there is paucity of information on its receptor viz., Stimulated by Retinoic Acid-6 (STRA6) with insulin resistance. To address this, we investigated the regulation of RBP4/STRA6 expression in 3T3-L1 adipocytes exposed to glucolipotoxicity (GLT) and in visceral adipose tissue (VAT) from high fat diet (HFD) fed insulin-resistant rats. 3T3-L1 adipocytes were subjected to GLT and other experimental maneuvers with and without vildagliptin or metformin. Real-time PCR and western-blot experiments were performed to analyze RBP4, STRA6, PPARγ gene and protein expression. Adipored staining and glucose uptake assay were performed to evaluate lipid and glucose metabolism. Oral glucose tolerance test (OGTT) and Insulin Tolerance Test (ITT) were performed to determine the extent of insulin resistance in HFD fed male Wistar rats. Total serum RBP4 was measured by quantitative sandwich enzyme-linked immunosorbent assay kit. Adipocytes under GLT exhibited significantly increased RBP4/STRA6 expressions and decreased insulin sensitivity/glucose uptake. Vildagliptin and metformin not only restored the above but also decreased the expression of IL-6, NFκB, SOCS-3 along with lipid accumulation. Furthermore, HFD fed rats exhibited significantly increased serum levels of RBP4 along with VAT expression of RBP4, STRA6, PPARγ, IL-6. These molecules were significantly altered by the vildagliptin/ metformin treatment. We conclude that RBP4/STRA6 pathway is primarily involved in mediating inflammation and insulin resistance in adipocytes and visceral adipose tissues under glucolipotoxicity and in insulin resistant rats.

Postnatal exposure to DINP was associated with greater alterations of lipidomic markers for hepatic steatosis than DEHP in postweaning mice

The toxicity of the endocrine disruptor di(2-ethylhexyl) phthalate (DEHP) has been extensively studied for its hormonal dysregulation, obesogenic effect and associated metabolic diseases. DEHP's primary substitute di-isononyl phthalate (DINP), however, although increased in annual production globally, requires better understanding of its health effect. Our previous work reported disruptions in plasma lipid profiles, but the metabolic responses following phthalate exposure in the liver, particularly the entire hepatic lipidome, have been lacking. A targeted lipidomic technique was applied to accurately quantify a total of 363 lipid species in the liver of neonatal mice after exposure to a daily dose of 4.8 mg/kg body weight/day from birth throughout lactation. Distinct patterns of disruption for each sum of lipid classes or sub-classes between the genders were the most noticeable. Following DINP administration, female pups were subject to greater changes in phosphatidylethanolamines, bis(monoacylglycero)phosphate and ceramides. In contrast, the males exhibited less changes in the phosphoglycerol backbone-based molecules, whereas glycerol and cholesterol esters were more disrupted by DINP. DEHP, however, induced less changes overall compared to DINP. These findings highlighted the predominant lipidomic disruption of DINP on glycerol (diacylglycerides and triacylglycerides) and/or cholesterol (in ester or free form) molecules in neonatal mice across genders, suggesting the genesis of hepatic steatosis occurring at as early as post weaning. Collectively, these findings question the suitability of DINP as a safe DEHP substitute and warrant further investigation on longer-term exposure to elucidate its effect on chronic liver diseases.

Plasticizers and Cardiovascular Health: Role of Adipose Tissue Dysfunction

Since the 1950s, the production of plastics has increased 200-fold, reaching 360 million tonnes in 2019. Plasticizers, additives that modify the flexibility and rigidity of the product, are ingested as they migrate into food and beverages. Human exposure is continuous and widespread; between 75 and 97% of urine samples contain detectable levels of bisphenols and phthalates, the most common plasticizers. Concern over the toxicity of plasticizers arose in the late 1990s, largely focused around adverse developmental and reproductive effects. More recently, many studies have demonstrated that exposure to plasticizers increases the risk for obesity, type 2 diabetes, and cardiovascular disease (CVD). In the 2000s, many governments including Canada, the United States and European countries restricted the use of certain plasticizers in products targeted towards infants and children. Resultant consumer pressure motivated manufacturers to substitute plasticizers with analogues, which have been marketed as safe. However, data on the effects of these new substitutes are limited and data available to-date suggest that many exhibit similar properties to the chemicals they replaced. The adverse effects of plasticizers have largely been attributed to their endocrine disrupting properties, which modulate hormone signaling. Adipose tissue has been well-documented to be a target of the disrupting effects of both bisphenols and phthalates. Since adipose tissue function is a key determinant of cardiovascular health, adverse effects of plasticizers on adipocyte signaling and function may underlie their link to cardiovascular disease. Herein, we discuss the current evidence linking bisphenols and phthalates to obesity and CVD and consider how documented impacts of these plasticizers on adipocyte function may contribute to the development of CVD.