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1.
Neuropsychologia ; 161: 108001, 2021 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-34450135

RESUMO

BACKGROUND: For 8 years, we have followed up a birth cohort comprising 241 mother-and-infant pairs living around the Da Nang airbase, a hot spot of dioxin contamination in Vietnam, and have reported the impacts of perinatal dioxin exposure on the neurodevelopment of children at various ages. In the present study, 9 years after birth, we investigated the effects of perinatal dioxin exposure on mu and theta rhythms by analyzing EEG power during the execution and observation of hand movements, which indicate mirror neuron system activity. METHODS: One hundred fifty-five 9-year-old children (86 boys and 69 girls) from the Da Nang birth cohort participated in the EEG examination with free viewing of hand movements. The dioxin levels in their mothers' breast milk, measured 1 month after birth, were used as perinatal dioxin exposure markers. A log transform of the ratio of EEG power during execution or observation of the hand movements relative to the power during observation of a bouncing ball for theta and mu rhythms was used to evaluate mirror neuron activity. RESULTS: In both brain hemispheres, the log power ratio in the theta band was significantly higher (i.e., less reduction of power) during observation of hand movements in girls exposed to high levels of TCDD. In boys, however, dioxin congeners other than TCDD, including HxCDDs and several PCDF congeners, contributed to increased log power ratios in the theta band. Particularly for PCDF congeners, the log power ratios in the lowest group among 4 exposure groups were lowest and significantly increased (i.e., decreasing reduction of power) with increasing dose. CONCLUSION: Perinatal TCDD exposure may influence the mirror neuron system of the brain, which plays an important role for social-emotional behavior in children, particularly in girls living in a hot spot of dioxin contamination in Vietnam.


Assuntos
Dioxinas , Neurônios-Espelho , Dibenzodioxinas Policloradas , Criança , Feminino , Mãos , Humanos , Lactente , Masculino , Dibenzodioxinas Policloradas/toxicidade , Gravidez , Vietnã
2.
Am J Hum Genet ; 108(9): 1611-1630, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34343493

RESUMO

Genome-wide association studies (GWASs) have identified a melanoma-associated locus on chromosome band 7p21.1 with rs117132860 as the lead SNP and a secondary independent signal marked by rs73069846. rs117132860 is also associated with tanning ability and cutaneous squamous cell carcinoma (cSCC). Because ultraviolet radiation (UVR) is a key environmental exposure for all three traits, we investigated the mechanisms by which this locus contributes to melanoma risk, focusing on cellular response to UVR. Fine-mapping of melanoma GWASs identified four independent sets of candidate causal variants. A GWAS region-focused Capture-C study of primary melanocytes identified physical interactions between two causal sets and the promoter of the aryl hydrocarbon receptor (AHR). Subsequent chromatin state annotation, eQTL, and luciferase assays identified rs117132860 as a functional variant and reinforced AHR as a likely causal gene. Because AHR plays critical roles in cellular response to dioxin and UVR, we explored links between this SNP and AHR expression after both 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and ultraviolet B (UVB) exposure. Allele-specific AHR binding to rs117132860-G was enhanced following both, consistent with predicted weakened AHR binding to the risk/poor-tanning rs117132860-A allele, and allele-preferential AHR expression driven from the protective rs117132860-G allele was observed following UVB exposure. Small deletions surrounding rs117132860 introduced via CRISPR abrogates AHR binding, reduces melanocyte cell growth, and prolongs growth arrest following UVB exposure. These data suggest AHR is a melanoma susceptibility gene at the 7p21.1 risk locus and rs117132860 is a functional variant within a UVB-responsive element, leading to allelic AHR expression and altering melanocyte growth phenotypes upon exposure.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Carcinoma de Células Escamosas/genética , Cromossomos Humanos Par 7 , Loci Gênicos , Melanócitos/metabolismo , Melanoma/genética , Receptores de Hidrocarboneto Arílico/genética , Neoplasias Cutâneas/genética , Alelos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Carcinogênese/genética , Carcinogênese/metabolismo , Carcinogênese/patologia , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patologia , Cromatina/química , Cromatina/metabolismo , Regulação da Expressão Gênica , Predisposição Genética para Doença , Genoma Humano , Estudo de Associação Genômica Ampla , Humanos , Melanócitos/efeitos dos fármacos , Melanócitos/patologia , Melanócitos/efeitos da radiação , Melanoma/metabolismo , Melanoma/patologia , Dibenzodioxinas Policloradas/toxicidade , Polimorfismo de Nucleotídeo Único , Cultura Primária de Células , Regiões Promotoras Genéticas , Receptores de Hidrocarboneto Arílico/metabolismo , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia , Banho de Sol , Raios Ultravioleta/efeitos adversos
3.
Sci Total Environ ; 797: 149130, 2021 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-34311349

RESUMO

Segmented filamentous bacteria (SFB) and Bacteroides fragilis are known to interact with the host immune response through the aryl hydrocarbon receptor (Ahr). 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), an environmental toxicant and a high-affinity Ahr ligand has the potential to modify the effect of SFB and B. fragilis. MicroRNAs (miRNA) with their role in regulating gene expression post-transcriptionally, may potentially be used to observe such interactions between SFB, B. fragilis, and TCDD. However, little is known regarding the impact of gut microbial members on miRNA expression or its modulation in the presence of an environmental toxicant. This information is important in understanding toxicant-mediated dysbiosis in gut microbiome and the resulting human health impacts. In this study, C57BL/6 germ-free (GF) mice were colonized with SFB and B. fragilis and administered 30 µg/kg TCDD every 4 d for 28 d and miRNA were measured. Compared to GF mice, colonization with SFB resulted in an increase in up- and down-regulated Ileal miRNAs. TCDD treatment of this group decreased the number of upregulated miRNA and increased the number of down-regulated miRNAs. Association with SFB and B. fragilis together had a similar but less pronounced effect in response to TCDD treatment. TCDD treatment of GF mice had no miRNA expression response. Immune and inflammatory responses and T-cell differentiation were the key functions impacted by these miRNAs. Overall, these results reveal that the host response to toxicants may also depend on the presence of specific gut microbial populations.


Assuntos
Microbioma Gastrointestinal , MicroRNAs , Dibenzodioxinas Policloradas , Animais , Imunidade , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/genética , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/genética
4.
Toxicol Sci ; 183(1): 154-169, 2021 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-34129049

RESUMO

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible poly-adenosine diphosphate (ADP)-ribose polymerase (TIPARP/PARP7), an aryl hydrocarbon receptor (AHR) target gene and mono-ADP-ribosyltransferase, acts as part of a negative feedback loop to repress AHR signaling. This process is prevented by a single H532A mutation in TIPARP that destroys its catalytic activity. We hypothesized that the loss of TIPARP catalytic activity would increase sensitivity to TCDD-induced toxicity in vivo. To test this, we created a catalytically deficient mouse line (TiparpH532A) by introducing a single H532A mutation in TIPARP. Treatment of mouse embryonic fibroblasts or hepatocytes isolated from TiparpH532A mice confirmed the increased TCDD-induced expression of the AHR target genes Cyp1a1, Cyp1b1, and Tiparp. TiparpH532A mice given a single injection of 10 µg/kg TCDD, a nonlethal dose in Tiparp+/+ mice, did not survive beyond day 10. All Tiparp+/+ mice survived the 30-day treatment. TCDD-treated TiparpH532A mice displayed increased expression of AHR target genes, increased steatohepatitis and hepatotoxicity. Hepatic RNA-sequencing revealed 7-fold more differentially expressed genes in TiparpH532A mice than in Tiparp+/+ mice (4542 vs 647 genes) 6 days after TCDD treatment. Differentially expressed genes included genes involved in xenobiotic metabolism, lipid homeostasis and inflammation. Taken together, these data further support TIPARP as a critical negative regulator of AHR activity and show that loss of its catalytic activity is sufficient to increase sensitivity to TCDD-induced steatohepatitis and lethality. Since TIPARP inhibition has recently emerged as a potential anticancer therapy, the impact on AHR signaling, TCDD and polycyclic aromatic hydrocarbon toxicity will need to be carefully considered under conditions of therapeutic TIPARP inhibition.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Dibenzodioxinas Policloradas , Adenosina Difosfato Ribose , Animais , Doença Hepática Induzida por Substâncias e Drogas/genética , Fibroblastos , Camundongos , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/genética
5.
Environ Int ; 154: 106658, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34082239

RESUMO

Cancer occurrence and development are closely related to the environment. Aryl hydrocarbon receptor (AhR) is an important receptor mediating the toxic effects of many environmental compounds, and is also involved in regulating tumor cell migration. Glioblastoma is the most malignant glioma and exhibits high motility, but the effects of AhR on the migration of glioblastoma are still unclear. We aimed to understand the role of AhR in the migration of this type of tumor cell and to explore the underlying molecular mechanism. In cultured human neuroblastoma cells (U87), we found that AhR overexpression or knockdown increased or suppressed the migration ability of U87 cells, respectively. Furthermore, inhibition of basal activation of the AhR pathway suppressed migration ability, suggesting a positive correlation between endogenous activity of the AhR pathway and cell migration. When the AhR pathway was activated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 6-formyl [3,2-b] carbazole (FICZ), the migration of U87 cells was inhibited by inducing the expression of a tumor suppressor, IL24, which is a downstream responsive gene of AhR activation. Moreover, a similar AhR-IL24-dependent mechanism for migration inhibition of TCDD was documented in a breast cancer cell line and a lung cancer cell line. This study demonstrated that AhR plays important roles in regulating the migration of glioblastoma, and the induction of the AhR-IL24 axis mediates the inhibition of migration in response to TCDD or FICZ treatment.


Assuntos
Glioblastoma , Dibenzodioxinas Policloradas , Linhagem Celular , Células Cultivadas , Glioblastoma/genética , Humanos , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/genética
6.
Environ Pollut ; 287: 117302, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34020259

RESUMO

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a well-known immunotoxic environmental pollutant. However, most immunotoxicology studies of TCDD were based on the animal models and the inner mechanisms have just focused on a few genes/proteins. In this study, the immune functions of THP-1-derived macrophages was measured with in-vitro bioassays after 24-h exposure of TCDD including environmentally relevant concentrations. RNA-seq and Weighted Gene Co-expression Network Analysis were used to characterize the immunotoxicity molecular mechanisms. Our study is the first report on the TCDD-induced effects of cell adhesion, morphology, and multiple cytokines/chemokines production on THP-1 macrophages. After TCDD treatment, we observed an inhibited cell adherence, probably attributed to the suppressed mRNA levels of adhesion molecules ICAM-1, VCAM-1 and CD11b, and a decrease in cell pseudopodia and expression of F-actin. The inflammatory cytokines TNF-α, IL-10 and other 8 cytokines/chemokines regulating granulocytes/T cells and angiogenesis were disrupted by TCDD. Alternative splicing event was found to be a sensitive target for TCDD. Using WGCNA, we identified 10 hub genes (TNF, SRC, FGF2, PTGS2, CDH2, GNG11, BDNF, WNT5A, CXCR5 and RUNX2) highly relevant to these observed phenotypes, suggesting AhR less important in the effects TCDD have on THP-1 macrophages than in other cells. Our findings broaden the understanding of TCDD immunotoxicity on macrophages and provide new potential targets for clarifying the molecular mechanisms.


Assuntos
Dibenzodioxinas Policloradas , Animais , Citocinas/genética , Macrófagos , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/genética , Linfócitos T , Fator de Necrose Tumoral alfa
7.
Front Immunol ; 12: 635748, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33936048

RESUMO

Xenobiotic-mediated activation of the aryl hydrocarbon receptor (AHR) is immunotoxic in a number of immune cell types, with the B cell being a well-established sensitive target. Recent advances have provided evidence that the B cell repertoire is a heterogeneous population, with subpopulations exhibiting vastly different cellular and functional phenotypes. Recent work from our laboratory identified the T cell specific kinase lck as being differentially regulated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which is a potent activator of AHR. While LCK is primarily expressed in T cells, a subset of CD5+ B cells also express LCK. CD5 positivity describes a broad class of B lymphocytes termed innate-like B cells (ILBs) that are critical mediators of innate immunity through constitutive secretion of polyvalent natural immunoglobulin M (IgM). We hypothesized that CD5+ ILBs may be sensitive to AHR-mediated immunotoxicity. Indeed, when CD5+ B cells were isolated from the CD19+ pool and treated with TCDD, they showed increased suppression of the CD40 ligand-induced IgM response compared to CD5- B cells. Further, characterization of the CD5+ population indicated increased basal expression of AHR, AHR repressor (AHRR), and cytochrome p450 family 1 member a1 (CYP1A1). Indeed the levels of AHR-mediated suppression of the IgM response from individual donors strongly correlated with the percentage of the B cell pool that was CD5+, suggesting that CD5+ B cells are more sensitive to AHR-mediated impairment. Together these data highlight the sensitive nature of CD5+ ILBs to AHR activation and provide insight into mechanisms associated with AHR activation in human B cells.


Assuntos
Subpopulações de Linfócitos B/efeitos dos fármacos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/agonistas , Antígenos CD5/metabolismo , Imunidade Inata/efeitos dos fármacos , Imunoglobulina M/metabolismo , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/agonistas , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Antígenos CD5/genética , Células Cultivadas , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A1/metabolismo , Humanos , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/metabolismo , Fenótipo , Proteína 2 Ligante de Morte Celular Programada 1/genética , Proteína 2 Ligante de Morte Celular Programada 1/metabolismo , Receptor de Morte Celular Programada 1/genética , Receptor de Morte Celular Programada 1/metabolismo , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo
8.
Artigo em Inglês | MEDLINE | ID: mdl-33985414

RESUMO

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an endocrine disrupting compound and persistent organic pollutant that has been associated with diabetes in several epidemiological studies. Oleuropein, a major phenolic compound in olive fruit, is a superior antioxidant and radical scavenger. This study aimed to examine the effects of oleuropein against TCDD-induced stress response in a pancreatic beta cell line, INS-1 cells. Cells were pre-incubated with various concentrations of oleuropein and then stimulated with TCDD (10 nM) for 48 hrs. When treated with TCDD, INS-1 cells produced robust amounts of prostaglandin E2 (PGE2) compared to the untreated control, and this increase was inhibited by oleuropein treatment. TCDD increased Ca2+-independent phospholipase A2 (iPLA2ß) level, but had no effect on Group 10 secretory phospholipase A2 (PLA2G10) level, while oleuropein deceased the levels of iPLA2ß and PLA2G10 in the presence of TCDD. Cyclooxygenase-1 (COX-1) was significantly increased by TCDD treatment and attenuated with oleuropein pretreatment. Oleuropein decreased TCDD-mediated production of JNK, TNF-α, and ROS. In addition, oleuropein increased Akt and GLUT2 levels suppressed by TCDD in INS-1 cells. Thus, the results suggest that oleuropein prevents pancreatic beta cell impairment by TCDD.


Assuntos
Poluentes Ambientais , Células Secretoras de Insulina , Dibenzodioxinas Policloradas , Glucosídeos Iridoides , Iridoides/farmacologia , Dibenzodioxinas Policloradas/toxicidade
9.
J Vet Med Sci ; 83(7): 1050-1058, 2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34024870

RESUMO

We reported the involvement of oxidative stress and prostaglandins including thromboxane and prostacyclin in pre-cardiac edema (early edema) caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). While the involvement of oxidative stress in TCDD-induced toxicity has been frequently reported, the mechanism of its action is still unclear. In the present study, oxidative stress inducers including paraquat, hydrogen peroxide (H2O2) and rotenone augmented early edema (edema) induced by a low concentration of TCDD (0.1 ppb) at 55 hr post fertilization (hpf), while each of them alone did not cause edema. Edema caused by TCDD plus oxidative stress inducers was almost abolished by antioxidants, an antagonist for thromboxane receptor (ICI-192,605) and an agonist for prostacyclin receptor (beraprost), suggesting that the site of action of these inducers was in the regular signaling pathway after activation of aryl hydrocarbon receptor type 2 (AHR2) by TCDD. Oxidative stress inducers also enhanced edema caused by an agonist for the thromboxane receptor (U46619), and the enhancement was also inhibited by antioxidants. Sulforaphane and auranofin, activators of Nrf2 that is a master regulator of anti-oxidative response, did not affect U46619-evoked edema but almost abolished TCDD-induced edema and potentiation by paraquat in both TCDD- and U46619-induced edema. Taken together, the results suggest that oxidative stress augments pre-cardiac edema caused by TCDD via activation of thromboxane receptor-mediated signaling in developing zebrafish. As paraquat and other oxidative stress inducers used also are environmental pollutants, interaction between dioxin-like compounds and exogenous source of oxidative stress should also be considered.


Assuntos
Dibenzodioxinas Policloradas , Peixe-Zebra , Animais , Edema Cardíaco/metabolismo , Edema Cardíaco/veterinária , Embrião não Mamífero/metabolismo , Peróxido de Hidrogênio/metabolismo , Larva/metabolismo , Estresse Oxidativo , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Proteínas de Peixe-Zebra/metabolismo
10.
Toxicology ; 456: 152772, 2021 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-33823233

RESUMO

Exposure to environmental toxicants such as all-trans retinoic acid (atRA) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) may cause cleft palate (CP), which process is related to DNA damage. Rad54B, an important DNA damage repaired protein, has been proved to be associated with non-syndromic cleft lip with palate (NSCLP). In the present study, we sought to clarify the role of Rad54B in palatal development and environment-induced CP. atRA (100 mg/kg) and TCDD (40 µg/kg) were used to induce CP in mice (C57BL/6 J mice). In this study, mouse embryonic heads were collected on embryonic day (E) 13.5∼16.5. The expression level of DNA repair protein Rad54 homolog B (Rad54B) was significantly decreased while those of the DNA double-strand breaks (DSBs) marker γ-H2A.X, apoptosis marker caspase-3 and p53 were significantly increased in the palatal shelves upon exposure to atRA and TCDD relative to the control. Primary mouse embryonic palatal mesenchymal cells (MEPMs) were cultured and transfected with siRNA or adenovirus in vitro to knock down or increase the level of Rad54B. Rad54B knockdown resulted in increased cellular S-phase arrest and apoptosis as well as decreased cell proliferation. Rad54B overexpression also increased apoptosis and reduced cell proliferation. Western blotting was used to detect the level of γ-H2A.X in transfected cells stimulated with etoposide (ETO, a DSBs inducer), and after 5 µM ETO stimulation of transfected MEPMs, the expression of γ-H2A.X was increased in Rad54B-knockdown cells. The expression of Mdm2, Mdmx and p53 with changes in Rad54B was also detected and coimmunoprecipitation was performed to analyze the combination of Mdm2 and p53 when Rad54B was changed in MEPMs. Knockdown of Rad54B inhibited the expression of Mdm2 and Mdmx, while the level of p53 increased. The coimmunoprecipitation results showed a decreased combination of Mdm2 and p53 when Rad54B was knocked down. Therefore, Rad54B can regulate the cell cycle, proliferation, and apoptosis of MEPMs. The loss of Rad54B increased the sensitivity of MEPMs to DSBs inducers, promoted apoptosis, and suppressed the proliferation of MEPMs by inhibiting the degradation of p53. Taken together, these findings suggest that Rad54B may play a key regulatory role in environment-induced CP.


Assuntos
Fissura Palatina/induzido quimicamente , Fissura Palatina/metabolismo , Dano ao DNA/efeitos dos fármacos , DNA Helicases/biossíntese , Dibenzodioxinas Policloradas/toxicidade , Animais , Dano ao DNA/fisiologia , Suscetibilidade a Doenças , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Gravidez , Efeitos Tardios da Exposição Pré-Natal/induzido quimicamente , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Teratógenos/toxicidade
11.
Int J Mol Sci ; 22(8)2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33921372

RESUMO

Recently, the mTOR signaling has emerged as an important player in the pathogenesis of psoriasis. We previously found that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced psoriatic skin inflammation was related to the inhibition of autophagy in keratinocytes. However, the effects and detailed molecular mechanisms of the mTOR inhibitor rapamycin and TCDD on psoriasis in vivo remain to be elucidated. In this study, we aimed to evaluate the effects of rapamycin and TCDD on skin lesions in imiquimod (IMQ)-induced psoriasis using a mouse model. TCDD aggravated skin inflammation in an IMQ-induced psoriatic mouse model. Furthermore, TCDD increased the expression of aryl hydrocarbon receptor (AHR), CYP1A1, proinflammatory cytokines, oxidative stress markers (NADPH oxidase (Nox) 2, Nox4), and phosphorylated P65NF-ĸB, whereas the expression of autophagy-related factors and the antioxidant marker nuclear factor-erythroid 2-related factor 2 (NRF2) decreased. Rapamycin reduced the aggravated skin inflammation induced by TCDD and restored TCDD-induced autophagy suppression and the increase of AHR expression, oxidative stress, and inflammatory response in the skin lesions of a psoriatic mouse model. In conclusion, we demonstrated that rapamycin alleviates TCDD-induced aggravated dermatitis in mice with imiquimod-induced psoriasis-like dermatitis through AHR and autophagy modulation.


Assuntos
Dermatite/tratamento farmacológico , Inflamação/tratamento farmacológico , Psoríase/tratamento farmacológico , Sirolimo/farmacologia , Animais , Autofagia/efeitos dos fármacos , Autofagia/genética , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Citocromo P-450 CYP1A1/genética , Dermatite/etiologia , Dermatite/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Imiquimode/toxicidade , Inflamação/induzido quimicamente , Inflamação/genética , Inflamação/patologia , Queratinócitos/efeitos dos fármacos , Camundongos , NADPH Oxidase 4/genética , Fator 2 Relacionado a NF-E2/genética , Dibenzodioxinas Policloradas/toxicidade , Psoríase/induzido quimicamente , Psoríase/genética , Psoríase/patologia , Receptores de Hidrocarboneto Arílico/genética
12.
Aquat Toxicol ; 234: 105786, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33735685

RESUMO

The aryl hydrocarbon receptor (AHR) has endogenous functions in mammalian vascular development and is necessary for mediating the toxic effects of a number of environmental contaminants. Studies in mice have demonstrated that AHR is necessary for the formation of the renal, retinal, and hepatic vasculature. In fish, exposure to the prototypic AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces expression of the AHR biomarker cyp1a throughout the developing vasculature and produces vascular malformations in the head and heart. However, it is not known whether the vascular structures that are sensitive to loss of AHR function are also disrupted by aberrant AHR activation. Here, we report that TCDD-exposure in zebrafish disrupts development of 1) the subintestinal venous plexus (SIVP), which vascularizes the developing liver, kidney, gut, and pancreas, and 2) the superficial annular vessel (SAV), an essential component of the retinal vasculature. Furthermore, we determined that TCDD exposure increased the expression of bmp4, a key molecular mediator of SIVP morphogenesis. We hypothesize that the observed SIVP phenotypes contribute to one of the hallmarks of TCDD exposure in fish - the failure of the yolk sac to absorb. Together, our data describe novel TCDD-induced vascular phenotypes and provide molecular insight into critical factors producing the observed vascular malformations.


Assuntos
Dibenzodioxinas Policloradas/toxicidade , Veia Retiniana/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/metabolismo , Animais , Animais Geneticamente Modificados/metabolismo , Proteína Morfogenética Óssea 4/genética , Proteína Morfogenética Óssea 4/metabolismo , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/metabolismo , Fígado/irrigação sanguínea , Veia Retiniana/crescimento & desenvolvimento , Veias/efeitos dos fármacos , Peixe-Zebra/crescimento & desenvolvimento , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
13.
Front Immunol ; 12: 635903, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33679792

RESUMO

Aryl hydrocarbon receptor (AhR), is a transcription factor and an environmental sensor that has been shown to regulate T cell differentiation. Interestingly, AhR ligands exert varying effects from suppression to exacerbation of inflammation through induction of Tregs and Th-17 cells, respectively. In the current study, we investigated whether the differential effects of AhR ligands on T cell differentiation are mediated by miRNA during delayed-type hypersensitivity (DTH) reaction against methylated Bovine Serum Albumin (mBSA). Treatment of C57BL/6 mice with TCDD attenuated mBSA-mediated DTH response, induced Tregs, decreased Th-17 cells, and caused upregulation of miRNA-132. TCDD caused an increase in several Treg subsets including inducible peripheral, natural thymic, and Th3 cells. Also, TCDD increased TGF-ß and Foxp3 expression. In contrast, treating mice with FICZ exacerbated the DTH response, induced inflammatory Th17 cells, induced IL-17, and RORγ. Analysis of miRNA profiles from draining lymph nodes showed that miR-132 was upregulated in the TCDD group and downregulated in the FICZ group. Transfection studies revealed that miRNA-132 targeted High Mobility Group Box 1 (HMGB1). Downregulation of HMGB1 caused an increase in FoxP3+ Treg differentiation and suppression of Th-17 cells while upregulation of HMGB1 caused opposite effects. Moreover, TCDD was less effective in suppressing DTH response and induction of Tregs in mice that were deficient in miR-132. In summary, this study demonstrates that TCDD and FICZ have divergent effects on DTH response and T cell differentiation, which is mediated through, at least in part, regulation of miRNA-132 that targets HMGB1.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/agonistas , Carbazóis/toxicidade , Diferenciação Celular/efeitos dos fármacos , Proteína HMGB1/metabolismo , Hipersensibilidade Tardia/metabolismo , MicroRNAs/metabolismo , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/agonistas , Linfócitos T Reguladores/efeitos dos fármacos , Células Th17/efeitos dos fármacos , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Células Cultivadas , Citocinas/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Proteína HMGB1/genética , Hipersensibilidade Tardia/genética , Hipersensibilidade Tardia/imunologia , Hipersensibilidade Tardia/prevenção & controle , Ligantes , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/genética , Fenótipo , Receptores de Hidrocarboneto Arílico/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Células Th17/imunologia , Células Th17/metabolismo
14.
J Mol Graph Model ; 105: 107886, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33706219

RESUMO

Unintentionally released in the environment as by-products of industrial activities, dioxins, exemplified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), represent a primary concern for human health. Exposure to these chemicals is known to produce a broad spectrum of adverse effects, including cancer. The main mechanism of action of TCDD in humans involves binding to the Aryl hydrocarbon Receptor (AhR). Although qualitatively established, TCDD capture by the AhR remains poorly characterized at the molecular level. Starting from a recently developed structural model of the human AhR PAS-B domain, in this work we attempt the identification of viable TCDD access pathways to the human AhR ligand binding domain by means of molecular dynamics. Based on the result of metadynamics simulations, we identify two main regions that may potentially serve as access paths for TCDD. For each path, we characterize the residues closely interacting with TCDD, thereby suggesting a possible mechanism for TCDD capture. Our results are reviewed and discussed in the light of the available information about Human AhR structure and functions.


Assuntos
Dibenzodioxinas Policloradas , Humanos , Ligantes , Dibenzodioxinas Policloradas/toxicidade , Ligação Proteica
15.
Toxicology ; 454: 152744, 2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33677009

RESUMO

Mitochondria are intracellular organelles responsible for biological oxidation and energy production. These organelles are susceptible to damage from oxidative stress and compensate for damage by increasing the number of copies of their own genome, mitochondrial DNA (mtDNA). Cancer and environmental exposure to some pollutants have also been associated with altered mtDNA copy number. Since exposures to polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have been shown to increase oxidative stress, we hypothesize that mtDNA copy number will be altered with exposure to these compounds. mtDNA copy number was measured in DNA from archived frozen liver and lung specimens from the National Toxicology Program (NTP) study of female Harlan Sprague Dawley rats exposed to TCDD (3, 10, or 100 ng/kg/day), dioxin-like (DL) PCB 126 (10, 100, or 1000 ng/kg/day), non-DL PCB 153 (10, 100, or 1000 µg/kg/day), and PCB 126 + PCB 153 (10 ng/kg/day + 10 µg/kg/day, 100 ng/kg/day + 100 µg/kg/day, or 1000 ng/kg/day + 1000 µg/kg/day, respectively) for 13 and 52 weeks. An increase in mtDNA copy number was observed in the liver and lung of rats exposed to TCDD and the lung of rats exposed to the mixture of PCB 126 and PCB 153. A statistically significant positive dose-dependent trend was also observed in the lung of rats exposed to PCB 126 and a mixture of PCB 153 and PCB 126, although in neither case was the control copy number significantly exceeded at any dose level. These exposures produced a range of pathological responses in these organs in the two-year NTP studies. Conversely, there was a significant decrease or no change in mtDNA copy number in the liver and lung of rats exposed to non-DL PCB 153. This is consistent with a general lack of PCB 153 mediated liver or lung injury in the NTP study, with the exception of liver hypertrophy. Together, the results suggest that an increase in mtDNA copy number may serve as a sensitive, early biomarker of mitochondrial injury and oxidative stress that contributes to the development of the toxicity of dioxin-like compounds.


Assuntos
DNA Mitocondrial/efeitos dos fármacos , Bifenilos Policlorados/toxicidade , Dibenzodioxinas Policloradas/toxicidade , Animais , Variações do Número de Cópias de DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Fígado/efeitos dos fármacos , Fígado/patologia , Pulmão/efeitos dos fármacos , Pulmão/patologia , Estresse Oxidativo/efeitos dos fármacos , Bifenilos Policlorados/administração & dosagem , Dibenzodioxinas Policloradas/administração & dosagem , Ratos , Ratos Sprague-Dawley
16.
Toxicol Sci ; 181(2): 285-294, 2021 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-33720361

RESUMO

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor in the Per-Arnt-Sim superfamily of environmental sensors that is linked to several metabolic diseases, including nonalcoholic fatty liver disease. Much remains unknown regarding the impact of genetic variation in AHR-driven disease, as past studies have focused on a small number of inbred strains. Recently, the presence of a wide range of interindividual variability amongst humans was reported in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the prototypical ligand of the AHR. In this study, a panel of 14 diverse mouse strains was exposed to TCDD for 10 days to characterize the AHR-mediated response across genetic backgrounds. Responses to TCDD are heavily dependent on genetic background. Although mice carry 1 of 4 Ahr alleles known to impact the affinity to AHR-ligands, we observed significant intra-allelic variability suggesting the presence of novel genetic modifiers of AHR signaling. A regression-based approach was used to scan for genes regulated by the AHR and/or associated with TCDD-induced phenotypes. The approach identified 7 genes, 2 of which are novel, that are likely regulated by the AHR based on association with hepatic TCDD burden (p ≤ .05). Finally, we identified 1 gene, Dio1, which was associated with change in percent body fat across the diverse set of strains (p ≤ .05). Overall, the results in this study exemplify the power of genetics-based approaches in identifying novel genes that are putatively regulated by the AHR.


Assuntos
Dibenzodioxinas Policloradas , Receptores de Hidrocarboneto Arílico , Animais , Humanos , Fígado/metabolismo , Camundongos , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais
17.
Aquat Toxicol ; 233: 105794, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33662880

RESUMO

Polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are environmental contaminants known to impact cardiac development, a key step in the embryonic development of most animals. To date, little is understood of the molecular mechanism driving the observed cardiac defects in exposed fishes. The literature shows PCB & TCDD derived cardiac defects are concurrent with, but not caused by, expression of cyp1A, due to activation of the aryl hydrocarbon receptor (AhR) gene activation pathway. However, in this study, detailed visualization of fish hearts exposed to PCBs and TCDD show that, in addition to a failure of cardiac looping in early heart development, the inner endocardial lining of the heart fails to maintain proper cell adhesion and tissue integrity. The resulting gap between the endocardium and myocardium in both zebrafish and Atlantic sturgeon suggested functional faults in endothelial adherens junction formation. Thus, we explored the molecular mechanism triggering cardiac defects using immunohistochemistry to identify the location and phosphorylation state of key regulatory and adhesion molecules. We hypothesized that PCB and TCDD activates AhR, phosphorylating Src, which then phosphorylates the endothelial adherens junction protein, VEcadherin. When phosphorylated, VEcadherin dimers, found in the endocardium and vasculature, separate, reducing tissue integrity. In zebrafish, treatment with PCB and TCDD contaminants leads to higher phosphorylation of VEcadherin in cardiac tissue suggesting that these cells have reduced connectivity. Small molecule inhibition of Src phosphorylation prevents contaminant stimulated phosphorylation of VEcadherin and rescues both cardiac function and gross morphology. Atlantic sturgeon hearts show parallels to contaminant exposed zebrafish cardiac phenotype at the tissue level. These data suggest that the mechanism for PCB and TCDD action in the heart is, in part, distinct from the canonical mechanism described in the literature and that cardiac defects are impacted by this nongenomic mechanism.


Assuntos
Embrião não Mamífero/efeitos dos fármacos , Coração/efeitos dos fármacos , Bifenilos Policlorados/toxicidade , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/metabolismo , Animais , Sinergismo Farmacológico , Embrião não Mamífero/anormalidades , Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Coração/embriologia , Miocárdio/metabolismo , Peixe-Zebra/crescimento & desenvolvimento
18.
Ecotoxicol Environ Saf ; 211: 111947, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33503546

RESUMO

The chicken (Gallus gallus), which has three aryl hydrocarbon receptor (AHR) isoforms (ckAHR1, ckAHR2, and ckAHR1ß) and two AHR nuclear translocator (ARNT) isoforms (ckARNT1 and ckARNT2), is highly sensitive to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and can serve as an avian model to gain an understanding of the mechanism underlying dioxin toxicity. To elucidate the mechanism of TCDD-induced immunotoxicity in avian species, we treated chicken embryos in ovo with graded concentrations of TCDD (1.5, 2.5, 3.0, 3.3, 3.5, and 4.0 µM). Initially, we measured mRNA expression levels of ckAHR and ckARNT isoforms and analyzed the T cell populations and transcriptome in the thymuses of TCDD-treated chicken embryos. Quantitative polymerase chain reaction analysis revealed that mRNA expressions of ckAHR1 and ckARNT2 were dominant in the thymus. Severe weight loss and thymus atrophy were observed in the TCDD-treated embryos. Immunophenotyping analyses demonstrated significant increases in CD4+CD8-CD25+ and CD4+CD8+CD25+ regulatory T cells (Tregs) populations following TCDD exposure, suggesting that TCDD suppresses T cell-mediated immune responses in chicken embryos. In addition, thymic transcriptome analyses intimated that alteration of the signaling pathways related to erb-b2 receptor tyrosine kinase 4 (ERBB4) and wnt family member 5A (WNT5A), and bone morphogenetic protein (BMP) may be associated with the TCDD-induced thymus atrophy. We also observed significantly altered expression levels of genes including interleukine 13 receptor subunit alpha 2 (IL13RA2), transforming growth factor beta 1 (TGFß1), collagen type III alpha 1 chain (COL3A1), and collagen type IX alpha 3 chain (COL9A3), implying immunosuppression, fibrosis development, and collagen deposition. Collectively, these findings suggest that TCDD exposure activates the ckAHR1-ckARNT2 signaling pathway and suppresses immune responses through the prompted differentiation to CD4+CD8-CD25+ and CD4+CD8+CD25+ Tregs and altered expressions of immune-related genes in the thymus of chicken embryos.


Assuntos
Poluentes Ambientais/toxicidade , Dibenzodioxinas Policloradas/toxicidade , Animais , Translocador Nuclear Receptor Aril Hidrocarboneto/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular , Embrião de Galinha , Galinhas/metabolismo , Sistema Imunitário/efeitos dos fármacos , Isoformas de Proteínas/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de Sinais , Linfócitos T , Transcriptoma
19.
Nat Commun ; 12(1): 290, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436590

RESUMO

The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes hepatic toxicity associated with prominent lipid accumulation in humans. Here, the authors report that the lysosomal copper transporter SLC46A3 is induced by TCDD and underlies the hepatic lipid accumulation in mice, potentially via effects on mitochondrial function. SLC46A3 was localized to the lysosome where it modulated intracellular copper levels. Forced expression of hepatic SLC46A3 resulted in decreased mitochondrial membrane potential and abnormal mitochondria morphology consistent with lower copper levels. SLC46A3 expression increased hepatic lipid accumulation similar to the known effects of TCDD exposure in mice and humans. The TCDD-induced hepatic triglyceride accumulation was significantly decreased in Slc46a3-/- mice and was more pronounced when these mice were fed a high-fat diet, as compared to wild-type mice. These data are consistent with a model where lysosomal SLC46A3 induction by TCDD leads to cytosolic copper deficiency resulting in mitochondrial dysfunction leading to lower lipid catabolism, thus linking copper status to mitochondrial function, lipid metabolism and TCDD-induced liver toxicity.


Assuntos
Proteínas de Transporte de Cobre/metabolismo , Cobre/metabolismo , Citosol/metabolismo , Homeostase , Lisossomos/metabolismo , Transportador de Folato Acoplado a Próton/metabolismo , Animais , Proteínas de Transporte de Cobre/genética , Citosol/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Hepatócitos/ultraestrutura , Homeostase/efeitos dos fármacos , Íons , Fígado/metabolismo , Lisossomos/efeitos dos fármacos , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Biológicos , Dibenzodioxinas Policloradas/toxicidade , Transportador de Folato Acoplado a Próton/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Especificidade por Substrato/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Triglicerídeos/metabolismo
20.
Toxicol Appl Pharmacol ; 412: 115390, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33387578

RESUMO

The kidneys are metabolically active organs with importance in several physiological tasks such as the secretion of soluble wastes into the urine and synthesizing glucose and oxidizing fatty acids for energy in fasting (non-fed) conditions. Once damaged, the metabolic capability of the kidneys becomes altered. Here, we define metabolic tasks in a computational modeling framework to capture kidney function in an update to the iRno network reconstruction of rat metabolism using literature-based evidence. To demonstrate the utility of iRno for predicting kidney function, we exposed primary rat renal proximal tubule epithelial cells to four compounds with varying levels of nephrotoxicity (acetaminophen, gentamicin, 2,3,7,8-tetrachlorodibenzodioxin, and trichloroethylene) for six and twenty-four hours, and collected transcriptomics and metabolomics data to measure the metabolic effects of compound exposure. For the transcriptomics data, we observed changes in fatty acid metabolism and amino acid metabolism, as well as changes in existing markers of kidney function such as Clu (clusterin). The iRno metabolic network reconstruction was used to predict alterations in these same pathways after integrating transcriptomics data and was able to distinguish between select compound-specific effects on the proximal tubule epithelial cells. Genome-scale metabolic network reconstructions with coupled omics data can be used to predict changes in metabolism as a step towards identifying novel metabolic biomarkers of kidney function and dysfunction.


Assuntos
Metabolismo Energético/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Nefropatias/induzido quimicamente , Túbulos Renais Proximais/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Acetaminofen/toxicidade , Animais , Células Cultivadas , Bases de Dados Genéticas , Metabolismo Energético/genética , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Feminino , Perfilação da Expressão Gênica , Redes Reguladoras de Genes , Gentamicinas/toxicidade , Nefropatias/genética , Nefropatias/metabolismo , Nefropatias/patologia , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/patologia , Metaboloma/genética , Metabolômica , Dibenzodioxinas Policloradas/toxicidade , Ratos Sprague-Dawley , Tricloroetileno/toxicidade
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