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• End-of-Life Tire (ELT) particles are obtained in the tire recycling process. • ELTs differ in terms of composition by the most studied Tire Road Wear Particles. • The toxicity of ELT particle suspensions was evaluated on zebrafish. • Alterations of detoxifying enzymes, swimming behaviour and heart rate were observed. • A wide plethora of proteins was modulated by the ELT suspension exposures. Million tons of tires become waste every year, and the so-called End-of-Life Tires (ELTs) are ground into powder (ELT-dp; size < 0.8 mm) and granules (ELT-dg; 0.8 < size < 2.5 mm) for recycling. The aim of this study was to evaluate the sub-lethal effects of three different concentrations (0.1, 1, and 10 mg/L) of aqueous suspensions from ELT-dp and ELT-dg on Danio rerio (zebrafish) larvae exposed from 0 to 120 h post-fertilization (hpf). Chronic effects were assessed through biomarkers, real-time PCR, and proteomics. We observed a significant increase in swimming behavior and heart rate only in specimens exposed to ELT-dp suspensions at 1 and 10 mg/L, respectively. Conversely, the activities of detoxifying enzymes ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST) showed significant modulation only in specimens exposed to ELT-dg groups. Although no effects were observed through real-time PCR, proteomics highlighted alterations induced by the three ELT-dp concentrations in over 100 proteins involved in metabolic pathways of aromatic and nitrogen compounds. The results obtained suggest that the toxic mechanism of action (MoA) of ELT suspensions is mainly associated with the induction of effects by released chemicals in water, with a higher toxicity of ELT-dp compared to ELT-dg. [ABSTRACT FROM AUTHOR]

Air liquid interface (ALI) exposure systems are gaining interest, and studies suggest enhanced response of lung cells exposed to particles at ALI as compared to submerged exposure, although the results have been somewhat inconsistent. Previous studies have used monocultures and measured particle deposition using assumptions including consistent particle deposition, particle density, and shape. This study exposed co-cultures of A549 and differentiated THP-1 cells to flame-generated particles using three exposure methods: ALI, pseudo-ALI, and submerged. The dose at ALI was measured directly, reducing the need for assumptions about particle properties and deposition. For all exposure methods an enhanced pro-inflammatory response (TNFα) and Cytochrome P450 (CYP1A1) gene expression, compared to their corresponding negative controls, was observed. ALI exposure induced a significantly greater TNFα response compared to submerged exposure. The submerged exposures exhibited greater induction of CYP1A1 than other exposure methods, although not statistically significant. Some of the factors behind the observed difference in responses for the three exposure methods include differences in physicochemical properties of particles in suspending media, delivered dose, and potential contribution of gas-phase species to cellular response in ALI exposure. However, given the difficulty and expense of ALI exposures, submerged exposure may still provide relevant information for particulate exposures. [ABSTRACT FROM AUTHOR]

Background: Exposure to ambient fine particulate matter (PM2.5) is associated with vascular diseases. Polycyclic aromatic hydrocarbons (PAHs) in PM2.5 are highly hazardous; however, the contribution of PM2.5-bound PAHs to PM2.5-associated vascular diseases remains unclear. The ToxCast high-throughput in vitro screening database indicates that some PM2.5-bound PAHs activate the aryl hydrocarbon receptor (AhR). The present study investigated whether the AhR pathway is involved in the mechanism of PM2.5-induced vascular toxicity, identified the PAH in PM2.5 that was the major contributor of AhR activation, and identified a biomarker for vascular toxicity of PM2.5-bound PAHs. Results: Treatment of vascular smooth muscle cells (VMSCs) with an AhR antagonist inhibited the PM2.5-induced increase in the cell migration ability; NF-κB activity; and expression of cytochrome P450 1A1 (CYP1A1), 1B1 (CYP1B1), interleukin-6 (IL-6), and osteopontin (OPN). Most PM2.5-bound PAHs were extracted into the organic fraction, which drastically enhanced VSMC migration and increased mRNA levels of CYP1A1, CYP1B1, IL-6, and OPN. However, the inorganic fraction of PM2.5 moderately enhanced VSMC migration and only increased IL-6 mRNA levels. PM2.5 increased IL-6 secretion through NF-κB activation; however, PM2.5 and its organic extract increased OPN secretion in a CYP1B1-dependent manner. Inhibiting CYP1B1 activity and silencing OPN expression prevented the increase in VSMC migration ability caused by PM2.5 and its organic extract. The AhR activation potencies of seven PM2.5-bound PAHs, reported in the ToxCast database, were strongly correlated with their capabilities of enhancing the migration ability of VSMCs. Benzo(k)fluoranthene (BkF) contributed the most to the AhR agonistic activity of ambient PM2.5-bound PAHs. The association between PM2.5-induced vascular toxicity, AhR activity, and OPN secretion was further verified in mice; PM2.5-induced intimal hyperplasia in pulmonary small arteries and OPN secretion were alleviated in mice with low AhR affinity. Finally, urinary concentrations of 1-hydroxypyrene, a major PAH metabolite, were positively correlated with plasma OPN levels in healthy humans. Conclusions: The present study offers in vitro, animal, and human evidences supporting the importance of AhR activation for PM2.5-induced vascular toxicities and that BkF was the major contributor of AhR activation. OPN is an AhR-dependent biomarker of PM2.5-induced vascular toxicity. The AhR activation potency may be applied in the risk assessment of vascular toxicity in PAH mixtures. [ABSTRACT FROM AUTHOR]

The strong tumorigenic capacity and treatment resistance made hepatocellular carcinoma (HCC) a huge threat to public health. ZNF165, the kruppel family of zinc-finger-containing transcription factors, is expressed in HCC; however, its specific role in HCC and the molecular mechanism are yet to be elucidated. In this study, we observed that ZNF165 was overexpressed in liver cancer tissues and the immune microenvironment; higher ZNF165 expression was correlated with lower overall survival in liver cancer patients. The ZNF165 knockdown in Bel7402 cells revealed the impairment of the tryptophan/kynurenine/AhR/CYP1A1 axis. Moreover, the knockdown of CYP1A1 significantly inhibited the proliferation and migration of HCC cells, and ZNF165 promoted the transcriptional activity of AhR by facilitating the nuclear translocation of CYP1A1. In conclusion, the present study argued that ZNF165 was highly expressed in liver tissues and the immune microenvironment. ZNF165 promoted the proliferation and migration of HCC cells by activating the tryptophan/kynurenine/AhR/CYP1A1 axis and promoting the expression of CYP1A1. [ABSTRACT FROM AUTHOR]

Highly porous three‐dimensional (3D) scaffolds can mimic the lobular structure of a human liver where hepatocytes are organized. However, 3D scaffolds with uniformly porous and oriented structures are challenging to fabricate without cross‐linking agents. Herein, this work presents a Pickering emulsion‐induced interface approach to construct aligned porous scaffolds for 3D cell cultures through the combined use of surface‐carboxylated cellulose nanofibers and chitosan nanofibers as stabilizers, and freezing/lyophilization to remove the oil phase. The obtained Pickering emulsions exhibit long‐term stability and their droplet sizes are tunable from 2.7 to 10.2 µm. Assembly at the oil–water interface can be modulated by controlling the NaCl dosage and oil phase proportion, resulting in porous foams with tunable porosity and versatile architectures as an in vitro alternative to the native liver microenvironment. The foams are noncytotoxic, confirmed using mouse fibroblast NIH/3T3 cells, and the cells grow both on the surface and in the internal structure of the foam. Notably, the 3D porous scaffolds are favorable microenvironments for the formation of human liver carcinoma HepG2 spheroidal cells, which exhibit liver‐like activity. This strategy based on Pickering emulsion templating provides a new avenue for constructing bioadaptive 3D scaffolds, specifically all‐biomass porous foams, for tissue engineering. [ABSTRACT FROM AUTHOR]

Several 5-(alkylsulfonyl)-1-substituted-2-(1H-pyrrol-2-yl)-1H-benzo[d]imidazole derivatives were synthesized and their antioxidant activities were investigated using lipid peroxidation (LPO) and 7-ethoxyresorufin O-deethylase (EROD) assays. Docking analysis with Human NAD[P]H-Quinone oxidoreductase 1 (NQO1) was also performed to gather thorough information about these compounds that have antioxidant activities. Moreover, their molecular descriptors and ADME properties were calculated using the SwissADME online program. As a result, most of our compounds possessed better affinity and created ample interactions with NQO1. The most potent compound 5j had LP inhibition value of 3.73 nmol/mg/min. Other compounds exhibited moderate activity on LP levels comparing to standard butylated hydroxy toluene (BHT). However, the inhibitory effect on EROD activity was not significant. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate whether low doses of zearalenone (ZEN) affect the carry-over of ZEN and its metabolites to intestinal tissues and the expression of CYP1A1 and GSTπ1 in the large intestine. Prepubertal gilts (with a BW of up to 14.5 kg) were exposed in group ZEN to daily ZEN5 doses of 5 μg/kg BW (n = 15); in group ZEN10, 10 μg/kg BW (n = 15); in group ZEN15, 15 μg/kg BW (n = 15); or were administered a placebo (group C, n = 15) throughout the experiment. After euthanasia, tissues were sampled on exposure days 7, 21, and 42 (D1, D2, and D3, respectively). The results confirmed that the administered ZEN doses (LOAEL, NOAEL, and MABEL) were appropriate to reliably assess the carry-over of ZEN. Based on the observations made during 42 days of exposure to pure ZEN, it can be hypothesized that all mycotoxins (ZEN, α-zearalenol, and β-zearalenol) contribute to a balance between intestinal cells and the expression of selected genes encoding enzymes that participate in biotransformation processes in the large intestine; modulate feminization processes in prepubertal gilts; and elicit flexible, adaptive responses of the macroorganism to mycotoxin exposure at the analyzed doses. [ABSTRACT FROM AUTHOR]

Dibenzyl trisulfide (DTS) is a natural compound with potential cancer‐preventive properties occurring in Petiveria alliacea L., an ethnomedicinal plant native to the Americas. Previous studies revealed its inhibitory activity toward cytochrome P450 (CYP)1 enzymes, key in the activation of environmental pollutants. Accordingly, the aim of this study was to design novel DTS analogues, aimed at improving not only inhibitory activity, but also specificity toward CYP1A1. This was achieved by targeting interactions with CYP1A1 residues of identified importance. Three‐dimensional structures for the novel analogues were subjected to molecular docking with several CYP isoforms, before being ranked in terms of binding affinity to CYP1A1. With three hydrogen bond donors, two hydrogen bond acceptors, a molecular mass of 361 Da, and a log P of 3.72, the most promising DTS analogue obeys Lipinski's rule of five. Following synthesis and in vitro validation of its CYP1A1‐inhibitory properties, this compound may be useful in future cancer‐preventive approaches. [ABSTRACT FROM AUTHOR]

Atlantic killifish populations have rapidly adapted to normally lethal levels of pollution in four urban estuaries. Through analysis of 384 whole killifish genome sequences and comparative transcriptomics in four pairs of sensitive and tolerant populations, we identify the aryl hydrocarbon receptor-based signaling pathway as a shared target of selection. This suggests evolutionary constraint on adaptive solutions to complex toxicant mixtures at each site. However, distinct molecular variants apparently contribute to adaptive pathway modification among tolerant populations. Selection also targets other toxicity-mediating genes and genes of connected signaling pathways; this indicates complex tolerance phenotypes and potentially compensatory adaptations. Molecular changes are consistent with selection on standing genetic variation. In killifish, high nucleotide diversity has likely been a crucial substrate for selective sweeps to propel rapid adaptation.

Cytochrome P450 (CYP) 1A1 is a phase I enzyme that can activate various compounds into reactive forms and thus, may contribute to carcinogenesis. In this study, we investigated the expression, methylation status, and functional role of CYP1A1 on prostate cancer cells. Increased expression of CYP1A1 was observed in all cancer lines (PC-3, LNCaP, and DU145) compared to BPH-1 (P < 0.05); and was enhanced further by 5-aza-2'-deoxycytidine treatment (P < 0.01). Methylation-specific PCR (MSP) and sequencing of bisulfite-modified DNA of the xenobiotic response element (XRE) enhancer site XRE-1383 indicated promoter methylation as a regulator of CYP1A1 expression. In tissue, microarrays showed higher immunostaining of CYP1A1 in prostate cancer than normal and benign prostatic hyperplasia (BPH; P < 0.001), and methylation analyses in clinical specimens revealed significantly lower methylation levels in cancer compared to BPH at all enhancer sites analyzed (XRE-1383, XRE-983, XRE-895; P < 0.01). Interestingly, smoking affected the XRE-1383 site where the methylation level was much lower in cancer tissues from smokers than non-smokers (P < 0.05). CYP1A1 levels are thus increased in prostate cancer and to determine the functional effect of CYP1A1 on cells, we depleted the gene in LNCaP and DU145 by siRNA. We observe that CYP1A1 knockdown decreased cell proliferation (P < 0.05) and increased apoptosis (P < 0.01) in both cell lines. We analyzed genes affected by CYP1A1 silencing and found that apoptosis-related BCL2 was significantly down-regulated. This study supports an oncogenic role for CYP1A1 in prostate cancer via promoter hypomethylation that is influenced by tobacco smoking, indicating CYP1A1 to be a promising target for prostate cancer treatment.

BackgroundThe aryl hydrocarbon receptor repressor (AhRR) is known to repress aryl hydrocarbon receptor (AhR) signaling, but very little is known regarding the role of the AhRR in vivo.ObjectiveThis study tested the role of AhRR in vivo in AhRR overexpressing mice on molecular and toxic end points mediated through a prototypical AhR ligand.MethodsWe generated AhRR-transgenic mice (AhRR Tg) based on the genetic background of C57BL/6J wild type (wt) mice. We tested the effect of the prototypical AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the expression of cytochrome P450 (CYP)1A1 and cytokines in various tissues of mice. We next analyzed the infiltration of immune cells in adipose tissue of mice after treatment with TCDD using flow cytometry.ResultsAhRR Tg mice express significantly higher levels of AhRR compared to wt mice. Activation of AhR by TCDD caused a significant increase of the inflammatory cytokines Interleukin (IL)-1β, IL-6 and IL-10, and CXCL chemokines in white epididymal adipose tissue from both wt and AhRR Tg mice. However, the expression of IL-1β, CXCL2 and CXCL3 were significantly lower in AhRR Tg versus wt mice following TCDD treatment. Exposure to TCDD caused a rapid accumulation of neutrophils and macrophages in white adipose tissue of wt and AhRR Tg mice. Furthermore we found that male AhRR Tg mice were protected from high-dose TCDD-induced lethality associated with a reduced inflammatory response and liver damage as indicated by lower levels of TCDD-induced alanine aminotransferase and hepatic triglycerides. Females from both wt and AhRR Tg mice were less sensitive than male mice to acute toxicity induced by TCDD.ConclusionIn conclusion, the current study identifies AhRR as a previously uncharacterized regulator of specific inflammatory cytokines, which may protect from acute toxicity induced by TCDD.CitationVogel CF, Chang WL, Kado S, McCulloh K, Vogel H, Wu D, Haarmann-Stemmann T, Yang GX, Leung PS, Matsumura F, Gershwin ME. 2016. Transgenic overexpression of aryl hydrocarbon receptor repressor (AhRR) and AhR-mediated induction of CYP1A1, cytokines, and acute toxicity. Environ Health Perspect 124:1071-1083; http://dx.doi.org/10.1289/ehp.1510194.

Background: Host-microbiota crosstalk has been implicated in multiple host metabolic pathway axes that regulate intestinal barrier function. Although constitutive cytochrome P4501A1 (CYP1A1) expression perturbs the microbiome-derived autoregulatory loop following enteric infection, little is known about the role of host CYP1A1 in modulating gut microbiome-mediated signaling during methicillin-resistant Staphylococcus aureus (MRSA)-induced abdominal sepsis and its effects on intestinal barrier integrity. Methods: Abdominal sepsis was induced by the intraperitoneal injection of MRSA in mice. The effect of CYP1A1 deficiency on gut barrier integrity was investigated using RNA sequencing, microbiome analyses, and targeted metabolomics. The microbiota-produced metabolites were validated in patients with sepsis and persistent MRSA infection. Results: Mice lacking CYP1A1 exhibited an altered gut microbiome, a reduced metabolic shift from lysine to cadaverine in the caecal contents and antimicrobial molecule production (Retnlb, Gbp7, and Gbp3), and they were protected against gut barrier disruption when subjected to MRSA challenge. These beneficial effects were validated in aryl hydrocarbon receptor (AHR) knockout (KO) mice by cohousing with CYP1A1 KO mice and abrogated after supplementation with cadaverine or Enterococcus faecalis , the primary microbiota genus for cadaverine synthesis. Antibiotic-driven gut dysbacteriosis impaired the survival benefit and disrupted the intestinal barrier integrity in CYP1A1 KO mice after MRSA infection. Furthermore, increased cadaverine levels in feces and serum were detected in critically ill patients with gut leakiness during persistent MRSA infection, whereas cadaverine was not detected in healthy controls. Additionally, microbiota-derived cadaverine induced enterocyte junction disruption by activating the histamine H4 receptor/nuclear factor-κB/myosin light-chain kinase signaling pathway. Conclusion: This study revealed the unexpected function of host CYP1A1 in microbiota-mediated cadaverine metabolism, with crucial consequences for dysbacteriosis following MRSA-induced abdominal sepsis, indicating that inhibiting CYP1A1 or blocking cadaverine-histamine H4 receptor signaling could be a potential therapeutic target against abdominal sepsis. Clinical Trial Registration: [http://www.chictr.org.cn/index.aspx], identifier [ChiCTR1800018646]. [ABSTRACT FROM AUTHOR]

Diplazium esculentum is one of the medicinal plants used by Dayak tribes in Central Kalimantan to cure acne. The potential of D. esculentum can be proved through information on the active compounds of the extract obtained in decoction and infusa methods. Thus, a liquid chromatography-mass spectrophotometry (LC-MS)-based method is developed to identify the active compounds of D. esculentum extract in either decoction method or infusa method. The chemical compound potential of D. esculentum extract was then analysed using bioinformatics approach based upon the database of PASS online server. Results showed that the D. esculentum extract contained 81 chemical compounds in decoction method and 68 compounds in infusa method, in which the dominant compound was flavonoid. Moreover, PASS online web server analysis found 7 flavonoid compound groups potential as anti-acne containing antisebor, AR expression inhibitor and CYP1A1 inhibitor. This information could be very useful for designing a clinical test on plant natural compound potential for traditional drug development. [ABSTRACT FROM AUTHOR]

Cruciferous vegetables and nuts are rich in indole-3-carbinol (I3C) and L-tryptophan (L-Trp), respectively, which can be converted upon ingestion into AhR ligands. Activation of AhR by dietary ligands contributes to unlocking its therapeutic potential in gastrointestinal homeostasis. In this study, some cruciferous vegetables (cabbage (red and white), cauliflower) and nuts (sunflower seed kernel, pistachio, cashew, walnut) were investigated for their effects on AhR- and Nrf2-mediated gene expression by using an in vitro digestion/Caco-2 cell culture model. Nuts induced AhR-pathway in a directly proportional manner with their L-Trp contents (sunflower induced the highest (5.3-fold) CYP1A1 expression). Nuts also showed Nrf2-dependent activities, although L-Trp standard did not. Vegetables activated only AhR-pathway, same with I3C standard, and red cabbage induced the highest CYP1A1 expression (9.6-fold). Results suggested the contribution of L-Trp and I3C in AhR-dependent activities of nuts and vegetables, respectively, although there appeared other bioactives to be identified in overall health aspects of these foods. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants as commercial products. PBDEs have been demonstrated to induce hepatic, reproductive, neural, and thyroid toxicity effects. This study aimed to clarify the potential intestinal toxicity effects of decabrominated diphenyl ether (PBDE‐209) in vivo and in vitro. First, we investigated the change of PBDE‐209 on oxidative stress in the intestine of mice. Subsequently, the potential toxicity mechanism of PBDE‐209 in vitro was investigated. Caco‐2 cells were treated with different concentrations of PBDE‐209 (1, 5, and 25 μmol/L) for 24 and 48 h. We determined the cell viability, reactive oxygen species (ROS) level, multiple cellular parameters, and relative mRNA expressions. The results showed that PBDE‐209 significantly injured the colon of mice, increased the intestinal levels of malondialdehyde (MDA), and changed the antioxidant enzyme activities. PBDE‐209 inhibited the proliferation and induced cytotoxicity of Caco‐2 cells. The change in ROS production and mitochondrial membrane potential (MMP) revealed that PBDE‐209 caused oxidative stress in Caco‐2 cells. The real‐time PCR assays revealed that PBDE‐209 inhibited the mRNA expression level of antioxidative defense factor, nuclear factor erythroid 2‐related factor 2 (Nrf2). Furthermore, the FAS and Cytochrome P450 1A1 (CYP1A1) mRNA expression levels were increased in Caco‐2 cells. These results suggested that PBDE‐209 exerts intestinal toxicity effects in vivo and in vitro and inhibits the antioxidative defense gene expression in Caco‐2 cells. This study provides an opportunity to advance the understanding of toxicity by the persistent environmental pollutant PBDE‐209 to the intestine. Highlights: Long‐time exposure to decabromodiphenyl ether (PBDE‐209) causes oxidative stress and induced intestinal damage in mice.PBDE‐209 induces cell apoptosis via upregulation of FAS expression in Caco‐2 cells.PBDE‐209 inhibits the Keap1‐Nrf2 antioxidant defense pathway in Caco‐2 cells. [ABSTRACT FROM AUTHOR]

The physiological conditions of an organism may influence its ability to cope with environmental stressors, such as contaminants. Biotransformation and the endocrine system interact with each other to promote animal's fitness. However, little is known regarding the interaction between hormones and response to pollutants such as polycyclic aromatic hydrocarbons (PAHs). In this in vitro study, we aimed to increase the knowledge regarding the effects of steroid hormones on ethoxyresorufin-O-deethylase (EROD) activity inhibited by contaminants. The effects on in vivo induced EROD activity of Anguilla anguilla were assessed by conducting single and combined exposures to fluoranthene (FL) and to physiological levels of two major steroid hormones (cortisol and 17ß-estradiol). Hepatic microsome exposure to the lowest concentrations of FL (0.1 and 0.3 µM), as well as to cortisol and 17ß-estradiol (E2), led to significant EROD activity induction. However, the highest tested concentrations of FL (0.9 and 2.7 µM) significantly inhibited this enzymatic activity. When microsomes were simultaneously exposed to 0.9 µM FL and one of the hormones, both cortisol and E2 were able to decrease the inhibitory effects, with the former completely reverting EROD activity inhibition. These findings support the idea that cortisol and E2 can help prevent the inhibitory effects of PAHs over biotransformation enzymes, highlighting the physiological relevance of these hormones. [ABSTRACT FROM AUTHOR]

Benzo[a]pyrene (B[a]P) is a known human carcinogen and plays a major function in the initiation of lung cancer at its first proximity. However, the underlying molecular mechanisms are less well understood. In this study, we investigated the impact of B[a]P treatment on the DNA methylation and mRNA levels of CYP1A1, GSTP1, and GSTM1 in human bronchial epithelial cells (16HBEs), and provide scientific evidence for the mechanism study on the carcinogenesis of B[a]P. We treated 16HBEs with DMSO or concentrations of B[a]P at 1, 2, and 5 mmol/L for 24 h, observed the morphological changes, determined the cell viability, DNA methylation, and mRNA levels of CYP1A1, GSTP1, and GSTM1. Compared to the DMSO controls, B[a]P treatment had significantly increased the neoplastic cell number and cell viability in 16HBEs at all three doses (1, 2, and 5 mmol/L), and had significantly reduced the CYP1A1 and GSTP1 DNA promoter methylation levels. Following B[a]P treatment, the GSTM1 promoter methylation level in 16HBEs was profoundly reduced at low dose group compared to the DMSO controls, yet it was significantly increased at both middle and high dose groups. The mRNA levels of CYP1A1, GSTP1, and GSTM1 were significantly decreased in 16HBEs following B[a]P treatment at all three doses. The findings demonstrate that B[a]P promoted cell proliferation in 16HBEs, which was possibly related to the altered DNA methylations and the inhibited mRNA levels in CYP1A1, GSTP1, and GSTM1. [ABSTRACT FROM AUTHOR]

A microcosm experiment was carried out to determine how benzo(a)pyrene (BaP) may affect marine meiofauna community, with a main emphasis on nematode structure and functional traits. Three increasing concentrations of BaP (i.e. 100, 200 and 300 ng/l, respectively) were used for 30 days. The results revealed a gradual decrease in the abundance of all meiobenthic groups (i.e. nematodes, copepods, amphipods, polychaetes and oligochaetes), except for isopods. Starting at concentrations of 200 and 300 ng/l BaP, respectively, significant changes were observed at community level. At taxonomic level, the nematode communities were dominated at the start of the experiment and also after being exposed or not to BaP by Odontophora villoti, explicable through its high ecologic ubiquity and the presence of well-developed chemosensory organs (i.e. amphids), which potentially increased the avoidance reaction following exposure to this hydrocarbon. Moreover, changes in the activity of several biochemical biomarkers (i.e. catalase 'CAT', gluthatione S-transferase 'GST', and ethoxyresorufin-O-deethylase 'EROD') were observed in the nematode species Oncholaimus campylocercoides, paralleled by significant decreases in CAT activity for non-gravid females compared to controls at concentrations of 25 ng/l BaP and associated with significant increase in GST and EROD activities for both types of individuals. [ABSTRACT FROM AUTHOR]

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that can be activated by structurally diverse compounds arising from the environment and the microbiota and host metabolism. Expanding evidence has been shown that the modulation of the canonical pathway of AHR occurs during several chronic diseases and that its abrogation might be of clinical interest for metabolic and inflammatory pathological processes. However, most of the evidence on the pharmacological abrogation of the AHR-CYP1A1 axis has been reported in vitro, and therefore, guidance for in vivo studies is needed. In this review, we cover the state-of-the-art of the pharmacodynamic and pharmacokinetic properties of AHR antagonists and CYP1A1 inhibitors in different in vivo rodent (mouse or rat) models of disease. This review will serve as a road map for those researchers embracing this emerging therapeutic area targeting the AHR. Moreover, it is a timely opportunity as the first AHR antagonists have recently entered the clinical stage of drug development. [ABSTRACT FROM AUTHOR]

The studies recommended the relationship between lots of polymorphisms with the head and neck cancers (HNCs) risk. Herein, we reported the association between the CYP1A1 MspI polymorphism and the risk of HNC in an updated meta-analysis. The PubMed/MEDLINE, Web of Science, Cochrane Library, and Scopus databases were searched until March 31, 2021, without any restrictions. Odds ratios (ORs) and 95% confidence intervals (CIs) were applied to assess a relationship between CYP1A1 MspI polymorphism and the HNC risk based on five applied genetic models by RevMan 5.3 software. Other analyses (sensitivity analysis, meta-regression, and bias analysis) were performed by CMA 2.0 software. Trial sequential analysis (TSA) was done by TSA software (version 0.9.5.10 beta). Among the databases and other sources, 501 recorded were identified that at last, 29 studies were obtained for the analysis. The pooled ORs were 1.28 (95%CI 1.09, 1.51; P = 0.003), 1.68 (95%CI 1.16, 2.45; P = 0.007), 1.24 (95%CI 1.03, 1.50; P = 0.02), 1.26 (95%CI 1.07, 1.48; P = 0.005), and 1.66 (95%CI 1.27, 2.16; P = 0.0002) for allelic, homozygous, heterozygous, recessive, and dominant models, respectively. Therefore, the m2 allele and m1/m2 and m2/m2 genotypes had significantly increased risks in HNC patients. With regards to stable results and enough samples, the findings of the present meta-analysis recommended that there was an association between CYP1A1 MspI polymorphism and the HNC risk. [ABSTRACT FROM AUTHOR]

Background: Lung cancer is the second most predominant reason for cancer deaths globally. It is estimated to be approximately 30% among the cancer deaths. Daidzein (DAZ) is a polyphenolic compound present commonly in soy-based plants and is proven to have various therapeutic properties. Objectives: In this study, we aimed to understand the immunomodulatory activity of DAZ in the mice model with benzo(a)pyrene (B(a)P)-induced lung carcinoma. Materials and Methods: The mice were divided into five groups: Group I served was the control group; Group II animals were challenged with B(a)P; Group III animals were treated with DAZ before challenge with B(a)P; Group IV animals were treated with DAZ after challenging the animals with B(a)P; and Group V animals were treated with DAZ alone till the end of the experimental period. Tumor incidence was calculated, and the following parameters were analyzed: Body weight, lung weight, total number of tumors, percentage of inhibition, immunoglobulin (Ig) levels (immunoglobulin G, immunoglobulin A, and immunoglobulin M), key marker enzymes, and proinflammatory cytokines in both treated and normal mice. The lung tissues were analyzed through the histopathological analysis. Results: According to our results, all the markers that favor the growth of cancer were increased in the lung cancer group. After the administration of DAZ, all the markers returned to their original levels. Conclusion: In conclusion, DAZ protected the cells against the B(a)P-induced inflammatory responses in lung cancer. [ABSTRACT FROM AUTHOR]

Heavy metals accumulated in the environment due to the mining industry may impact on the health of exposed wild animals with consequences at the population level via survival and selection of the most resistant individuals. The detection and quantification of shifts in gene frequencies or in the genetic structure in populations inhabiting polluted sites may be used as early indicators of environmental stress and reveal potential 'candidate gene biomarkers' for environmental health assessment. We had previously observed that specimens of the Greater white-toothed shrew (Crocidura russula) from two heavy metal mines in Southern Portugal (the Aljustrel and the Preguiça mines) carried physiological alterations compared to shrews from an unpolluted site. Here, we further investigated whether these populations showed genetic differences in genes relevant for physiological homeostasis and/or that are associated with pathways altered in animals living under chronic exposure to pollution, and which could be used as biomarkers. We analysed the mitochondrial cytochrome b (Cytb) gene and intronic and/or exonic regions of four nuclear genes: CYP1A1, LCAT, PRPF31, and p53. We observed (1) population differences in allele frequencies, types of variation, and diversity parameters in the Cytb, CYP1A1, and p53 genes; (2) purifying selection of Cytb in the mine populations; (3) genetic differentiation of the two mine populations from the reference by the p53 gene. Adding to our previous observations with Mus spretus, we provide unequivocal evidence of a population effect exerted by the contaminated environment of the mines on the local species of small mammals. [ABSTRACT FROM AUTHOR]

Background: Genetic variations of aryl hydrocarbon receptor (AHR) pathway genes could influence the imbalanced immune response to xenobiotics. Therefore, we aimed to investigate the polymorphism of AHR pathway genes in systemic lupus erythematosus (SLE) patients in association with smoking. Methods: Genomic DNA from patients (N = 107) and controls (N = 105) of a population from northeast of Iran was used for genotyping of CYP1A1 T>C (rs4646903) and AHRR C>G (rs2292596) variants. The SLEDAI score and smoking status of the patients were registered. The AHR activity was estimated by CYP1A1 and CYP1B1 gene expression in peripheral blood mononuclear cells (PBMC). Results: The C allele in rs4646903 (odds ratio [OR] = 2.67) and G allele in rs2292596 (OR = 1.79) SNPs were significantly associated with the increased risk of SLE. The AHR pathway was more active in high‐risk CYP1A1/AHRR: C/G haplotype. The most severe disease was observed in smoker patients with high‐risk haplotype and both smoking (Exp (β) = 9.5) and high‐risk CYP1A1/AHRR (C/G) haplotype (Exp (β) = 3.7) can significantly increase the likelihood of having severe (SLEDAI ≥ 20) SLE disease activity. Conclusion: Our findings indicated the association of xenobiotic‐metabolizing genes (CYP1A1, AHRR) polymorphisms with the susceptibility to SLE and disease severity regarding the smoking background, suggesting the interaction of gene and environmental risk factors in SLE pathogenesis. [ABSTRACT FROM AUTHOR]

• Nrf2 negatively regulates BDE-209-induced oxidative stress. • BDE-209 triggers mitochondrial dysfunction, disordered calcium homeostasis, and DNA damage. • The toxicity mechanism of BDE-209 may be related to the dysfunction of organelles and Nrf2 signaling pathways. Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants. They are constantly detected in terrestrial, ocean, and atmospheric systems, and it is of particular concern that these fat-soluble xenobiotics may have a negative impact on human health. This study aimed to evaluate the toxic effect and underlying mechanism of decabromodiphenyl ether (BDE-209) on human liver in a HepG2 cell model. The results showed that BDE-209 significantly induced HepG2 cells apoptosis, increased intracellular reactive oxygen species (ROS), disturbed [Ca 2+] homeostasis and mitochondrial membrane potential (MMP), and caused nuclear shrinkage and DNA double-strand breaks. BDE-209 also significantly decreased the activities of antioxidant parameters, superoxide dismutase (SOD), total antioxygenic capacity (T-AOC), glutathione (GSH), and total glutathione (T-GSH). The up-regulation of the Aryl hydrocarbon receptor (AhR)/cytochrome P4501A1 (CYP1A1) signaling pathway indicates that after long-term and high-dose exposure, BDE-209 may be a liver carcinogen. Interestingly, HepG2 cells attempt to metabolize BDE-209 through the Nrf2-mediated antioxidant pathway. These findings help elucidate the mechanisms of BDE-209-induced hepatotoxicity in humans. [ABSTRACT FROM AUTHOR]

Small molecular weight protein kinase inhibitors are frequently used tools to unravel the complex network of cellular signal transduction under certain physiological and pathophysiological conditions. 4-amino-5-(4-chlorophenyl)-7-(dimethylethyl)pyrazolo[3,4-d]pyrimidine (PP2) is a widely used compound to block the activity of Src family kinases, the major group of non-receptor tyrosine kinases, which trigger multiple cellular signaling pathways. Here, we show that PP2 induces cytochrome P450 1A1 mRNA expression and enzyme activity in a dose-dependent manner in human HepG2 hepatoma cells and NCTC 2544 keratinocytes. By means of reporter gene assays, RNA interference, electrophoretic mobility shift assay, and competitive ligand-binding assay, we further demonstrate that PP2 is a ligand for the aryl hydrocarbon receptor (AHR), an intracellular chemosensor that regulates xenobiotic metabolism, environmental stress responses, and immune functions. Upon ligand-dependent activation, the AHR translocates into the nucleus and dimerizes with the AHR nuclear translocator (ARNT) to modulate the expression of its target genes. In addition, AHR activation is frequently accompanied by an activation of the tyrosine kinase c-Src, resulting in stimulation of cell-surface receptors and downstream signal transduction. As PP2 activates the AHR/ARNT pathway by simultaneously blocking c-Src-mediated alternative signaling routes, this compound may be a suitable tool to study the contribution of the different AHR-dependent signaling pathways to biological processes and adverse outcomes. On the other hand, the unexpected property of PP2 to stimulate AHR/ARNT signaling should be carefully taken into account in future investigations in order to avoid a false interpretation of experimental results and molecular interrelations.

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that mediates the toxic and biological effects of structurally diverse chemicals, including the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). As part of a larger effort to identify the full spectrum of chemicals that can bind to and activate the AhR, we have examined the ability of several naturally occurring marine-derived brominated indoles and brominated (methylthio)indoles (collectively referred to as brominated indoles) to bind to the AhR and stimulate AhR-dependent gene expression. Incubation of mouse, rat, and guinea pig recombinant cell lines containing a stably transfected AhR-responsive luciferase reporter gene with eight brominated indoles revealed that all compounds stimulated luciferase reporter gene activity, although some species-specific differences were observed. All compounds induced significantly more luciferase activity when incubated with cells for 4 h as compared to 24 h, demonstrating that these compounds are transient activators of the AhR signaling pathway. Three of the brominated indoles induced CYP1A1 mRNA in human HepG2 cells in vitro and Cyp1a mRNA in zebrafish embryos in vivo. The identification of the brominated indoles as direct ligands and activators/agonists of the AhR was confirmed by their ability to compete with [(3)H]TCDD for binding to the AhR and to stimulate AhR transformation and DNA binding in vitro. Taken together, these results indicate that marine-derived brominated indoles are members of a new class of naturally occurring AhR agonists.

Indigo carmine removal from aqueous solutions was investigated by the electrocoagulation process and biochemical responses of Gammarus pulex to solutions before and after treatment were studied. Electrocoagulation experiments in the first stage were carried out with central composite design (CCD) using response surface methodology (RSM). Optimization of process variables that maximize indigo carmine removal by electrocoagulation process was carried out by using a second-order model within the studied test range of various process variables. According to the optimization results, optimum conditions for obtaining 82.55% maximum indigo carmine removal were pH 5.86, a current density of 13.31 mA/cm2, an indigo carmine concentration of 20.01 mg/L, and a time period of 115.80 min. Under optimum conditions for indigo carmine removal, the amount of sludge formed was 0.928 kg/m3, electrode consumption was 0.0305 kg/m3, and energy consumption was 7.461 kWh/m3. The operating cost was calculated as 0.79 US$/m3 under treatment conditions where optimum indigo carmine removal was achieved. In the second stage, G. pulex was exposed to treated and untreated synthetic indigo carmine solutions obtained from experiments according to optimum conditions in order to investigate the biochemical response for 24 and 96 h. Treatment efficiency was evaluated with superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and cytochrome P450 1A1 (CYP1A1) biomarkers. Results clearly showed that the electrocoagulation process was a simple and effective treatment method for the decolorization of wastewaters containing indigo carmine dye. The bioassays used in the present study provided good credibility for checking the detoxification of treated and untreated indigo carmine solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] Cytochrome P450 1A1 (CYP1A1) is a member of a subfamily of enzymes involved in the metabolism of both endogenous and exogenous substrates and the chemical activation of xenobiotics to carcinogenic derivatives. Here, the effects of nicotine, a major psychoactive compound present in cigarette smoke, on CYP1A1 expression and human hepatocellular carcinoma (HepG2) cell proliferation were investigated. Nicotine stimulated CYP1A1 expression via the transcription factors, activator protein 1, nuclear factor-kappa B, and the aryl hydrocarbon receptor (AhR) signaling pathway. Pharmacological inhibition and mutagenesis studies indicated that p38 mitogen-activated protein kinase, as well as RelA (or p65), mediated the upregulation of CYP1A1 of nicotine in HepG2 cells. The antioxidant compound, N-acetyl-cysteine, abrogated nicotine-activated production of reactive oxygen species and inhibited CYP1A1 expression by nicotine. Furthermore, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was inhibited by diphenyleneiodonium (an NADPH oxidase inhibitor). Thus, these results demonstrated that AhR played an important role in nicotine-induced CYP1A1 expression. Additionally, liver hepatocellular carcinoma HepG2 cells treated with nicotine exhibited markedly enhanced proliferation via CYP1A1 expression and Akt activation. [ABSTRACT FROM AUTHOR]

Tris (2,3-dibromopropyl) isocyanurate (TDBP-TAZTO or TBC) is a heterocyclic hexabromated flame retardant. It is widely used during the production of many synthetic compounds. High concentrations of TDBP-TAZTO were found in river water, surface sediments, soil, earthworms, and carp tissues. Moreover, it has been shown that this compound can cross the blood–brain barrier and accumulate in the gut and brain of carp. The aryl hydrocarbon receptor (AhR) has been characterized as a multifunctional intracellular sensor and receptor. AhR is an activator of cytochrome P450 1A1 and 1A2, which metabolize various toxic compounds. The aim of the study was to explain how/whether TDBP-TAZTO increases the expression and/or activity of the CYP1A1 enzyme and the AhR and TUBB3 expression during SH-SY5Y cell differentiation. SH-SY5Y cells were differentiated for 7 and 14 days using retinoic acid. Cell viability, ethoxyresorufin-O-deethylase (EROD) activity, and mRNA expression of CYP1A1, AhR, and TUBB3 were assessed. Our experiment showed that, during the differentiation process, the ability of TDBP-TAZTO to induce EROD activity in SH-SY5Y cells subsequently decreased, which may have been an effect of cell differentiation into neurons. Moreover, the results suggest that TDBP-TAZTO can affect the differentiation process. Since no CYP2B6 mRNA expression was detected, the CAR receptor may not be involved in the TDBP-TAZTO mechanism of action. However, more research is needed in this field to elucidate this mechanism precisely. [ABSTRACT FROM AUTHOR]

Epidemiological studies have shown that head and neck cancer (HNC) is a complex multistage process that in part involves exposure to a combination of carcinogens and the capacity of certain drug-metabolising enzymes including cytochrome P450 (CYP) to detoxify or activate such carcinogens. In this study, CYP1A1, CYP1B1 and CYP2W1 expression in HNC was correlated with potential as target for duocarmycin prodrug activation and selective therapy. In the HNC cell lines, elevated expression was shown at the gene level for CYP1A1 and CYP1B1 whereas CYP2W1 was hardly detected. However, CYP2W1 was expressed in FaDu and Detroit-562 xenografts and in a cohort of human HNC samples. Functional activity was measured in Fadu and Detroit-562 cells using P450-Glo™ assay. Antiproliferative results of duocarmycin prodrugs ICT2700 and ICT2706 revealed FaDu and Detroit-562 as the most sensitive HNC cell lines. Administration of ICT2700 in vivo using a single dose of ICT2700 (150 mg/kg) showed preferential inhibition of small tumour growth (mean size of 60 mm3) in mice bearing FaDu xenografts. Significantly, our findings suggest a potential targeted therapeutic approach to manage HNCs by exploiting intratumoural CYP expression for metabolic activation of duocarmycin-based prodrugs such as ICT2700. [ABSTRACT FROM AUTHOR]

Most studies of indole derivatives such as IAA produced by intestinal microbiota have been based on the premise that binding to AhR leads to biological responses. We previously revealed that IAA binds to more than one receptor, and thus the present study aimed to identify a new receptor for IAA and analyze its mechanism of action. We found that the TLR4 antagonist TAK-242 did not affect the IAA-induced increase in CYP1A1 expression at 3 h and decreased TNFα expression at 8 days. However, TAK-242 alleviated decreased TNFα expression induced by IAA at 2 days and promoted IAA-induced increased CYP1A1 expression by inhibiting JNK activation at 8 days. Taken together, TLR4 may be a novel IAA receptor with signaling pathways that regulate CYP1A1 and TNFα expression depending on the culture stage of Caco-2 cells. Furthermore, our findings offer important clues for elucidating the action mechanisms of indole derivatives that affect hosts. [ABSTRACT FROM AUTHOR]

Cytochrome P450 1A1 (CYP1A1) metabolizes estrogens, melatonin, and other key endogenous signaling molecules critical for embryonic/fetal development. The enzyme has increasing expression during pregnancy, and its inhibition or knockout increases embryonic/fetal lethality and/or developmental problems. Here, we present a virtual screening model for CYP1A1 inhibitors based on the orthosteric and predicted allosteric sites of the enzyme. Using 1001 reference compounds with CYP1A1 activity data, we optimized the decision thresholds of our model and classified the training compounds with 68.3% balanced accuracy (91.0% sensitivity and 45.7% specificity). We applied our final model to 11 known CYP1A1 orthosteric binders and related compounds, and found that our ranking of the known orthosteric binders generally agrees with the relative activity of CYP1A1 in metabolizing these compounds. We also applied the model to 22 new test compounds with unknown/unclear CYP1A1 inhibitory activity, and predicted 16 of them are CYP1A1 inhibitors. The CYP1A1 potency and modes of inhibition of these 22 compounds were experimentally determined. We confirmed that most predicted inhibitors, including drugs contraindicated during pregnancy (amiodarone, bicalutamide, cyproterone acetate, ketoconazole, and tamoxifen) and environmental agents suspected to be endocrine disruptors (bisphenol A, diethyl and dibutyl phthalates, and zearalenone), are indeed potent inhibitors of CYP1A1. Our results suggest that virtual screening may be used as a rapid tier-one method to screen for potential CYP1A1 inhibitors, and flag them out for further experimental evaluations. [ABSTRACT FROM AUTHOR]

To investigate the influences of aryl hydrocarbon (AHR), cytochrome P450 (CYP1A1), epoxide hydrolase 1 (EPHX1), and glutathione S-transferase P1 (GSTP1) genetic polymorphisms on small-for-gestational-age (SGA) infants. This nested case-control study (126 cases and 381 controls) was based on a prospective cohort study in Shanxi Province, China. We collected the general information of subjects using questionnaire and identified their single nucleotide polymorphisms by the MassARRAY genotyping platform. The polymorphisms of CYP1A1 (rs4646421 and rs4646903) and EPHX1 (rs1051740) were significantly associated with SGA. Neonates of women with EPHX1 (rs1051740) and GSTP1 (rs1695) variant alleles were at a significantly increased risk of SGA compared with the reference group (OR = 5.26; 95% CI, 1.08–25.66), as were neonates of women with CYP1A1 (rs4646903) and EPHX1 (rs1051740) variant alleles (OR = 7.11; 95% CI, 1.55–32.62). The results of strata analysis by AHR (rs2282883 and rs17137566) showed that the associations between the polymorphisms of CYP1A1 (rs4646421 and rs4646903) EPHX1 (rs1051740), GSTP1 (rs1695) and SGA were of significance in women with variant heterozygous or homozygous genotype. CYP1A1 (rs4646421 and rs4646903), EPHX1 (rs1051740), and GSTP1 (rs1695) genetic variances might increase the risk of SGA. AHR (rs2282883 and rs17137566) resulted in estimated effects varying across strata on CYP1A1 (rs4646421 and rs4646903), EPHX1 (rs1051740), and GSTP1 (rs1695). [ABSTRACT FROM AUTHOR]

This study aimed to reveal the toxic characteristics of di-(2-ethylhexyl) phthalate (DEHP) by examining the biochemical and histopathological changes in Gammarus pulex, exposed to different doses of DEHP. For this purpose, the lethal concentration 50 (LC50) value of the DEHP was determined by using a static test and found to be 0.079 ± 0.01 ppm. Three subletal doses of DEHP were applied to the G. pulex for 24 and 96 h. Superoxide dismutase (SOD), catalase (CAT), cytochrome P450 1A1 (CYP1A1), and glutathione S-transferase (GST) activities were measured using commercial ELISA kits. The caspase method, which is an immunohistochemical analysis method, was used to determine the apoptosis that occurred in the G. pulex. The results showed that the CYP1A1 activities decreased in the groups exposed to different doses of DEHP compared to the control group (p > 0.05). CAT activity was found to increase in the application groups at the 24 and 96 h compared to the control group. In addition, it was found that SOD and GST activities increased at the 96 h compared to the control group. In light of the microscope examination of the model organism, hemolymphatic lacunae filled with hemolymph and reduction or absence of hemolymphatic ducts were observed especially in the G. pulex gills. Collapse of the gills and hyperplasia were observed after 96 h. As a result, it is suggested that changes in SOD, CAT, and GST activities can potentially be used as sensitive biomarkers for risk assessment in the environment and increased immunoreactivity in G. pulex caused by DEHP depending on increased application doses and application times. [ABSTRACT FROM AUTHOR]

Longevity is a complex process controlled by environmental and genetic factors. We evaluated the association of seven drug metabolising and DNA-repair gene polymorphisms with longevity in an Italian cohort. A sample of 756 subjects aged 18-98 was genotyped for CYP1A1 (rs1048943, A>G), GSTM1 (rs 1183423000, presence/absence), GSTT1 (rs1601993659, presence/absence), GSTP1 (rs1695, A>G), XRCC1 (rs1799782, C>T), XRCC1 (rs25489, A>G) and XPC (rs2228001, A>C) gene polymorphisms. The association between the studied gene polymorphisms and longevity was evaluated by dividing the sample into three age groups: 18–50, 51–85, and 86–98. We observed a significant decrease in the frequency of the GSTT1 null, GSTP1 G and XPC C alleles in the oldest group with respect to the youngest one. We also obtained the same results when dividing the sample into 18–85 and 86–98 age groups. The general linear model analyses confirmed a significant decreasing trend with age of the above mentioned alleles. We hypothesised that these minor alleles, being important in the sensitivity against the development of different types of cancer, may reflect a reduced life-expectancy in carrier subjects and may explain their significantly lower frequency observed among subjects belonging to the oldest age group. [ABSTRACT FROM AUTHOR]

Soluble epoxide hydrolase (sEH) is an emerging therapeutic target in a number of diseases that have inflammation as a common underlying cause. sEH limits tissue levels of cytochrome P450 (CYP) epoxides derived from omega-6 and omega-3 polyunsaturated fatty acids (PUFA) by converting these antiinflammatory mediators into their less active diols. Here, we explored the metabolic effects of a sEH inhibitor (t-TUCB) in fat-1 mice with transgenic expression of an omega-3 desaturase capable of enriching tissues with endogenous omega-3 PUFA. These mice exhibited increased CYP1A1, CYP2E1, and CYP2U1 expression and abundant levels of the omega-3-derived epoxides 17,18-epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic (19,20-EDP) in insulin-sensitive tissues, especially liver, as determined by LC-ESI-MS/MS. In obese fat-1 mice, t-TUCB raised hepatic 17,18-EEQ and 19,20-EDP levels and reinforced the omega-3-dependent reduction observed in tissue inflammation and lipid peroxidation. t-TUCB also produced a more intense antisteatotic action in obese fat-1 mice, as revealed by magnetic resonance spectroscopy. Notably, t-TUCB skewed macrophage polarization toward an antiinflammatory M2 phenotype and expanded the interscapular brown adipose tissue volume. Moreover, t-TUCB restored hepatic levels of Atg12-Atg5 and LC3-II conjugates and reduced p62 expression, indicating up-regulation of hepatic autophagy. t-TUCB consistently reduced endoplasmic reticulum stress demonstrated by the attenuation of IRE-1α and eIF2α phosphorylation. These actions were recapitulated in vitro in palmitate-primed hepatocytes and adipocytes incubated with 19,20-EDP or 17,18-EEQ. Relatively similar but less pronounced actions were observed with the omega-6 epoxide, 14,15-EET, and nonoxidized DHA. Together, these findings identify omega-3 epoxides as important regulators of inflammation and autophagy in insulin-sensitive tissues and postulate sEH as a druggable target in metabolic diseases.

Apiole (1-allyl-2,5-dimethoxy-3,4-methylenedioxybenzene) and parsley leaves ethanolic extract containing it inhibit the rat liver microsomal ethoxy- and methoxyresorufin- O -deacetylase activities associated with cytochrome P450 (CYP) 1A1 and 1A2, respectively. Cytochrome P4501A subfamily metabolizes environmental mutagens and several drugs, leading to the formation of mutagenic metabolites. Docking analysis showed that residue Phe123 within the active site of the CYP1A1 enzyme is bound to apiole through a π/π stacking of its benzene ring. In the case of 1A2, its Phe226 interacts with the dioxolane ring of apiole. Furthermore, apiole behaves as a mixed-type inhibitor of bacterial human recombinant CYP1A1. To explore one of the possible biological implications of this inhibitory effect, we tested the capacity of apiole and the parsley ethanolic extract to interfere with the mutagenicity of the promutagen 2-amino-3,8-dimethylimidazo[4,5- f ]quinoxaline (MeIQx) metabolized by CYP1A subfamily. As expected, both apiole and the plant extract reduced the number of revertant colonies of Salmonella typhimurium TA98 Ames strain after exposure to MeIQx, reaching a 78 % and 100 % reduction, respectively. Neither apiol nor parsley extract were mutagenic to the TA98 strain. We speculate that consuming apiole, a constituent of edible herbs, in conjunction with the utilization of pharmaceuticals metabolized by the CYP1A subfamily, may result in herb-drug interactions. Furthermore, the consumption of apiole by individuals who regularly ingest fresh vegetables may contribute to the low incidence of cancer observed in those who adhere to such a dietary regimen. • Parsley extracts showed antimutagenic activity to cope with MeIQx. • Apiole, the component of parsley odor, inhibits cytochrome P450 1A1 and 1A2. • Docking assays explain how apiole interacts with the CYP1A subfamily. [ABSTRACT FROM AUTHOR]

Human activities have directly impacted the environment, causing significant ecological imbalances. From the different contaminants resulting from human activities, plastics are of major environmental concern. Due to their high use and consequent discharge, plastics tend to accumulate in aquatic environments. There, plastics can form smaller particles (microplastics, MPs), due to fragmentation and weathering, which are more prone to interact with aquatic organisms and cause deleterious effects, including at the basis of different food webs. This study assessed the effects of two microplastics (polyethylene terephthalate, PET; and polypropylene, PP; both of common domestic use) in the freshwater cladoceran species Daphnia magna. Toxic effects were assessed by measuring reproductive traits (first brood and total number of offspring), and activities of biomarkers involved in xenobiotic metabolism (phase I: cytochrome P-450 isoenzymes CYP1A1, 1A2 and 3A4; phase II/conjugation: glutathione S-transferases; and antioxidant defense (catalase)). Both MPs showed a potential to significantly reduce reproductive parameters in D. magna. Furthermore, PET caused a significant increase in some isoenzymes of CYP450 in acutely exposed organisms, but this effect was not observed in chronically exposed animals. Similarly, the activity of the antioxidant defense (CAT) was significantly increased in acutely exposed animals, but not in chronically exposed organisms. This pattern of effects suggests a possible mechanism of long-term adaptation to the presence of the tested MPs. In conclusion, the herein tested MPs have shown the potential to induce deleterious effects on D. magna mainly observed in terms of the reproductive outcomes. Changes at the biochemical level seems transient and are not likely to occur in long term, environmentally exposed crustaceans. [Display omitted] • MPs cause deleterious effects on D. magna. • PET and PP MPs significantly impaired D. magna reproductive outcome. • CAT and GSTs activities were increased in acutely exposed animals. [ABSTRACT FROM AUTHOR]

Tris(2-butoxyethyl) phosphate (TBOEP) is an organophosphorus flame retardant ubiquitously present in the environment and even the human body. TBOEP is toxic in multiple tissues, which forms dealkylated and hydroxylated metabolites under incubation with human hepatic microsomes; however, the impact of TBOEP metabolism on its toxicity, particularly mutagenicity (typically requiring metabolic activation), is left unidentified. In this study, the mutagenicity of TBOEP in human hepatoma cell lines (HepG2 and C3A) and the role of specific CYPs were studied. Through molecular docking, TBOEP bound to human CYP1A1, 1B1, 2B6 and 3A4 with energies and conformations favorable for catalyzing reactions, while the conformations of its binding with human CYP1A2 and 2E1 appeared unfavorable. In C3A cells (endogenous CYPs being substantial), TBOEP exposing for 72 h (2-cell cycle) at low micromolar levels induced micronucleus, which was abolished by 1-aminobenzotriazole (inhibitor of CYPs); in HepG2 cells (CYPs being insufficient) TBOEP did not induce micronucleus, whose effect was however potentiated by pretreating the cells with PCB126 (CYP1A1 inducer) or rifampicin (CYP3A4 inducer). TBOEP induced micronucleus in Chinese hamster V79-derived cell lines genetically engineered for stably expressing human CYP1A1 and 3A4, but not in cells expressing the other CYPs. In C3A cells, TBOEP selectively induced centromere protein B-free micronucleus (visualized by immunofluorescence) and PIG-A gene mutations, and elevated γ-H2AX rather than p-H3 (by Western blot) which indicated specific double-strand DNA breaks. Therefore, this study suggests that TBOEP may induce DNA/chromosome breaks and gene mutations in human cells, which requires metabolic activation by CYPs, primarily CYP1A1 and 3A4. [Display omitted] • Tris(2-butoxyethyl) phosphate (TBOEP) induced DNA breaks and gene mutations. • TBOEP formed micronuclei in human hepatoma C3A cells by a clastogenic mechanism. • Mutagenicity of TBOEP was dependent on metabolic activation by human CYP1A1 and 3A4. • Pretreating HepG2 cells with AhR and PXR activators potentiated the effect of TBOEP. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) and dioxins are potential causes of multiple diseases by activating the aryl hydrocarbon receptor (AhR) pathway. Health risk assessment of chemicals primarily relies on the relative potency factor (RPF), although its accuracy may be limited when solely using EC50 values. The induction of cytochrome P4501A1 (CYP1A1) serves as a biomarker for AhR activation and is an integrator of dioxin-like toxicity. Here, we present a method for evaluating the risks associated with AhR activation using mathematical models of dose- CYP1A1 induction. The dose-effect curves for certain PAHs and dioxins, including Ant, BghiP, 1,2,3,4,7,8-HxCDD, and others, exhibited a non-classical S-shaped form. The toxic equivalent factor (TEF) profiles revealed a broad range of toxic equivalent factor values. The TEFs for PAHs ranged from approximately 0.01 to 6, with higher values being observed when the concentration was less than 10−10 M, with the exceptions of Ace, Phe, and BghiP. Most congeners of dioxins got the lowest TEF value at around 10−10 M, ranging from 0.04 to 1.00. The binding affinity of AhR to ligands did not display a strong correlation with the EC50 of CYP1A1 expression, suggesting that the AhR-mediated effects of PAHs and dioxins are not fixed but instead fluctuate with the dose. Air samples acquired from a parking area were used to compare the proficiency of RPF and our current approach. In the current method, naphthalene and chrysene were the primary contributors of PAHs to AhR-mediated risks in parking lots air samples, respectively. However, the contributions of naphthalene and chrysene could be disregarded in the RPF approach. • BaP and 2,3,7,8-TCDF were the strongest inducers of AhR activation in PAHs and dioxins, respectively. • Toxicity equivalency factor values varied from −0.5–6 and 0–2 for PAHs and dioxins. • Free energy and CYP1A1 expression had strong correlation in PAHs, but not in dioxins. • Nap is the main pollutant for AhR-mediated risk in actual air samples in our approach, whereas a BaP in the RPF approach. [ABSTRACT FROM AUTHOR]

Predicting the metabolic activation mechanism and potential hazardous metabolites of environmental endocrine-disruptors is a challenging and significant task in risk assessment. Here the metabolic activation mechanism of benzophenone-3 catalyzed by P450 1A1 was investigated by using Molecular Dynamics, Quantum Mechanics/Molecular Mechanics and Density Functional Theory approaches. Two elementary reactions involved in the metabolic activation of BP-3 with P450 1A1: electrophilic addition and hydrogen abstraction reactions were both discussed. Further conversion reactions of epoxidation products, ketone products and the formaldehyde formation reaction were investigated in the non-enzymatic environment based on previous experimental reports. Binding affinities analysis of benzophenone-3 and its metabolites to sex hormone binding globulin indirectly demonstrates that they all exhibit endocrine-disrupting property. Toxic analysis shows that the eco-toxicity and bioaccumulation values of the benzophenone-3 metabolites are much lower than those of benzophenone-3. However, the metabolites are found to have skin-sensitization effects. The present study provides a deep insight into the biotransformation process of benzophenone-3 catalyzed by P450 1A1 and alerts us to pay attention to the adverse effects of benzophenone-3 and its metabolites in human livers. [Display omitted] • The metabolic mechanism and metabolites of BP-3 was revealed by MD, QM/MM and DFT approaches. • The reactivity of the electrophilic addition and the hydrogen abstraction pathways were compared. • Formaldehyde decomposed from BP-3 was revealed in the non-enzymatic environment. • The endocrine-disrupting potential of BP-3 and its metabolites were estimated through binding affinities analysis to SHBG. • The potential adverse effects, such as eco-toxicity, bioaccumulation and skin-sensitization, were assessed theoretically. [ABSTRACT FROM AUTHOR]

The accidental spill of petroleum asphalt cement (PAC) in São Raimundo (SR Harbor, located on the Rio Negro (Manaus, Amazonas, Brazil) was monitored through the analysis of polyciclic aromatic hydrocarbons (PAHs) in water and a set of biomarkers in fishes (exposure biomarkes: PAHs-type metabolites concentrations in bile; the activities of ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in liver. Effect biomarkers: lipid peroxidation concentration (LPO) in liver, acetylcholinesterase activity in brain, and genotoxic DNA damage in erythrocytes). Two fish species, Acarichthys heckelii and Satanoperca jurupari , were collected 10, 45, and 90 days after the PAC spill in São Raimundo. At the same time, fish were collected from the Tupé Sustainable Development Reserve (Tupé) which served as a reference area. The sampling periods were related to the rising waters of the natural flood pulse of the Rio Negro. Higher concentrations of PAHs in water were observed at 10 and 45 days and returned to the values of TP 90 days after the PAC spill, a period in which harbor waters rose about 0.2 m. Unlike the PAHs in water, biomarker responses in both fish species significantly increased following the PAC spill in SR. Hepatic ethoxyresorufin-O-deethylase (EROD), PAH-like metabolites in bile, and erythrocyte DNA damage increases, together with inhibition of acetylcholinesterase (AChE) activity in the brain were the most evident responses for both fish species. The calculated pyrolytic index showed mixed sources of PAHs (petrogenic and pyrolytic). The applied PCA-FA indicated important relationships between dissolved organic carbon (DOC) and PAHs concentrations in water, where DOC and PAHs concentrations contributed to biomarkers responses for both fish species in all collection periods. [Display omitted] • PAH concentrations in water decreased over time. • Biomarker responses in fishes increased over time. • Mixed sources were found for PAH-like metabolites in bile. • EROD, DNA damage, AChE, and PAH-like were the most responsive biomarkers. • Correlations between DOC, PAHs in water, and biomarkers in fishes were observed. [ABSTRACT FROM AUTHOR]

Numerous studies reported the concentration of agonists of aryl hydrocarbon receptor (AhR) in indoor dust by target chemical analysis or the biological effects of activating the AhR by indoor extracts, but the major AhR agonists identification in indoor dust were rarely researched. In the present study, the indoor dust samples were collected for 7-ethoxyresorufin O-deethylase (EROD) assay and both non-targeted and targeted chemical analysis for AhR agonists by gas chromatography quadrupole time-of-flight mass spectrometry and gas chromatography–mass spectrometry analysis. Coupled with non-targeted analysis and toxicity Forecaster (ToxCast)/Tox21 database, 104 ToxCast chemicals were screened to be able to induce EROD response. The combination of targeted chemical analyses and biological effects evaluation indicated that PAHs, dibutyl phthalate (DBP) and Cypermethrin might be the important AhR-agonists in different indoor dust and mainly contributed in 1.84%–97.56 % (median: 26.62%) of total observed biological effects through comparing toxic equivalency quotient derived from chemical analysis with biological equivalences derived from bioassay. DBP and cypermethrin seldom reported in the analysis of AhR agonists should raise great concern. In addition, the present results in experiment of synthetic solution of 4 selected AhR-agonists pointed out that some unidentified AhR agonists existed in indoor dust. [Display omitted] • Thirty-eight out of 52 samples showed positive results in the EROD experiment. • PAHs, DBP and cypermethrin might be the major AhR agonists. • Simulation assay indicated that some unidentified AhR agonists existed in dust. [ABSTRACT FROM AUTHOR]

PIWI-interacting RNAs (piRNAs) is an emerging class of small non-coding RNAs that has been recently reported to have functions in infertility, tumorigenesis, and multiple diseases in humans. Previously, 5 toxicity pathways were proposed from hundreds of toxicological studies that underlie BaP-induced lung injuries, and a "Bottom-up" approach was established to identify small non-coding RNAs that drive BaP-induced pulmonary effects by investigating the activation of these pathways in vitro , and the expression of the candidate microRNAs were validated in tissues of patients with lung diseases from publications. Here in this study, we employed the "Bottom-up" approach to identifying the roles of piRNAs and further validated the mechanisms in vivo using mouse acute lung injury model. Specifically, by non-coding RNA profiling in in vitro BaP exposure, a total of 3 suppressed piRNAs that regulate 5 toxicity pathways were proposed, including piR-004153 targeting CYP1A1 , FGFR1 , ITGA5 , IL6R , NGRF , and SDHA , piR-020326 targeting CDK6 , and piR-020388 targeting RASD1. Animal experiments demonstrated that tail vein injection of respective formulated agomir-piRNAs prior to BaP exposure could all alleviate acute lung injury that was shown by histopathological and biochemical evidences. Immunohistochemical evaluation focusing on NF-kB and Bcl-2 levels showed that exogenous piRNAs protect against BaP-induced inflammation and apoptosis, which further support that the inhibition of the 3 piRNAs had an important impact on BaP-induced lung injuries. This mechanism-driven, endpoint-supported result once again confirmed the plausibility and efficiency of the approach integrating in silico , in vitro , and in vivo evidences for the purpose of identifying key molecules. [Display omitted] • The bottom-up approach could efficiently unravel mechanisms behind alterations. • The feasibility was demonstrated from in silico prediction to in vitro and in vivo validation. • 3 piRNAs were identified as protecting against BaP-induced lung injury. [ABSTRACT FROM AUTHOR]

Recent studies have shown that the long-term antihypertensive action of soluble epoxide hydrolase inhibition (sEH) in angiotensin-II (AngII)-dependent hypertension might be mediated by the suppression of intrarenal AngII levels. To test this hypothesis, we examined the effects of acute (2 days) and chronic (14 days) sEH inhibition on blood pressure (BP) in transgenic rats with inducible AngII-dependent hypertension. AngII-dependent malignant hypertension was induced by 10 days' dietary administration of indole-3-carbinol (I3C), a natural xenobiotic that activates the mouse renin gene in Cyp1a1-Ren-2 transgenic rats. BP was monitored by radiotelemetry. Acute and chronic sEH inhibition was achieved using cis-4-(4-(3-adamantan-1-yl-ureido)cyclohexyloxy) benzoic acid, given at doses of 0.3, 3, 13, 26, 60 and 130 mg/L in drinking water. At the end of experiments, renal concentrations of epoxyeicosatrienoic acids, their inactive metabolites dihydroxyeicosatrienoic acids and AngII were measured. Acute BP-lowering effects of sEH inhibition in I3C-induced rats was associated with a marked increase in renal epoxyeicosatrienoic acids to dihydroxyeicosatrienoic acids ratio and acute natriuresis. Chronic treatment with cis-4-(4-(3-adamantan-1-yl-ureido)cyclohexyloxy) benzoic acid in I3C-induced rats elicited dose-dependent persistent BP lowering associated with a significant reduction of plasma and kidney AngII levels. Our findings show that the acute BP-lowering effect of sEH inhibition in I3C-induced Cyp1a1-Ren-2 transgenic rats is mediated by a substantial increase in intrarenal epoxyeicosatrienoic acids and their natriuretic action without altering intrarenal renin-angiotensin system activity. Long-term antihypertensive action of cis-4-(4-(3-adamantan-1-yl-ureido)cyclohexyloxy) benzoic acid in I3C-induced Cyp1a1-Ren-2 transgenic rats is mediated mostly by suppression of intrarenal AngII concentration.

CYP1A1 bioactivates several procarcinogens and detoxifies several xenobiotic compounds. Transcription of CYP1A1 is highly induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) via the aryl hydrocarbon receptor. We recently described an RNAi high throughput screening performed in the Hepa-1 mouse hepatoma cell line, which revealed that SIN3A is necessary for the induction of CYP1A1-dependent ethoxyresorufin-o-deethylase (EROD) enzymatic activity by TCDD. In the current studies, we sought to provide insight into the role of SIN3A in this process, particularly because studies on SIN3A have usually focused on its repressive activity on transcription. We report that ectopic expression of human SIN3A in Hepa-1 cells enhanced EROD induction by TCDD and efficiently rescued TCDD induction of EROD activity in cells treated with an siRNA to mouse SIN3A, thus validating a role for SIN3A in CYP1A1 induction. We demonstrate that SIN3A is required for TCDD induction of the CYP1A1 protein in Hepa-1 cells but not for expression of the aryl hydrocarbon receptor protein. In addition, siRNAs for SIN3A decreased TCDD-mediated induction of CYP1A1 mRNA and EROD activity in human hepatoma cell line Hep3B. We establish that TCDD treatment of Hepa-1 cells rapidly increases the degree of SIN3A binding to both the proximal promoter and enhancer of the Cyp1a1 gene and demonstrate that increased binding to the promoter also occurs in human Hep3B, HepG2, and MCF-7 cells. These studies establish that SIN3A physically interacts with the CYP1A1 gene and extends the transcriptional role of SIN3A to a gene that is very rapidly and dramatically induced.

Triclocarban (3,4,4'-trichlorocarbanilide; TCC) is an antibacterial agent used in personal care products such as bar soaps. Small amounts of chemical are absorbed through the epidermis. Recent studies show that residues of reactive TCC metabolites are bound covalently to proteins in incubations with keratinocytes, raising concerns about the potential toxicity of this antimicrobial agent. To obtain additional information on metabolic activation of TCC, this study characterized the reactive metabolites trapped as glutathione conjugates. Incubations were carried out with (14)C-labeled TCC, recombinant CYP1A1 or CYP1B1, coexpressed with cytochrome P450 reductase, glutathione-S-transferases (GSH), and an NADPH-generating system. Incubations containing CYP1A1, but not 1B1, led to formation of a single TCC-GSH adduct with a conversion rate of 1% of parent compound in 2 hours. Using high-resolution mass spectrometry and diagnostic fragmentation, the adduct was tentatively identified as 3,4-dichloro-3'-glutathionyl-4'-hydroxycarbanilide. These findings support the hypothesis that TCC is activated by oxidative dehalogenation and oxidation to a quinone imine. Incubations of TCDD-induced keratinocytes with (14)C-TCC yielded a minor radioactive peak coeluting with TCC-GSH. Thus, we conclude that covalent protein modification by TCC in TCDD-induced human keratinocyte incubations is mainly caused by activation of TCC by CYP1A1 via a dehalogenated TCC derivative as reactive species.