Latest Publications

@article{vyhlidalova_gut_2020,

title = {Gut Microbial Catabolites of Tryptophan Are Ligands and Agonists of the Aryl Hydrocarbon Receptor: A Detailed Characterization.},

author = {Barbora Vyhlídalová and Kristýna Krasulová and Petra Pečinková and Adéla Marcalíková and Radim Vrzal and Lenka Zemánková and Jan Vančo and Zdeněk Trávníček and Jan Vondráček and Martina Karasová and Sridhar Mani and Zdeněk Dvořák},

doi = {10.3390/ijms21072614},

issn = {1422-0067},

year  = {2020},

date = {2020-04-01},

journal = {International journal of molecular sciences},

volume = {21},

number = {7},

abstract = {We examined the effects of gut microbial catabolites of tryptophan on the aryl hydrocarbon receptor (AhR). Using a reporter gene assay, we show that all studied catabolites are low-potency agonists of human AhR. The efficacy of catabolites differed substantially, comprising agonists with no or low (i3-propionate, i3-acetate, i3-lactate, i3-aldehyde), medium (i3-ethanol, i3-acrylate, skatole, tryptamine), and high (indole, i3-acetamide, i3-pyruvate) efficacies. We displayed ligand-selective antagonist activities by i3-pyruvate, i3-aldehyde, indole, skatole, and tryptamine. Ligand binding assay identified low affinity (skatole, i3-pyruvate, and i3-acetamide) and very low affinity (i3-acrylate, i3-ethanol, indole) ligands of the murine AhR. Indole, skatole, tryptamine, i3-pyruvate, i3-acrylate, and i3-acetamide induced CYP1A1 mRNA in intestinal LS180 and HT-29 cells, but not in the AhR-knockout HT-29 variant. We observed a similar CYP1A1 induction pattern in primary human hepatocytes. The most AhR-active catabolites (indole, skatole, tryptamine, i3-pyruvate, i3-acrylate, i3-acetamide) elicited nuclear translocation of the AhR, followed by a formation of AhR-ARNT heterodimer and enhanced binding of the AhR to the CYP1A1 gene promoter. Collectively, we comprehensively characterized the interactions of gut microbial tryptophan catabolites with the AhR, which may expand the current understanding of their potential roles in intestinal health and disease.},

note = {Place: Switzerland},

keywords = {*Gastrointestinal Microbiome/drug effects, Animals, Aryl hydrocarbon receptor, Aryl Hydrocarbon/*agonists/*metabolism, Basic Helix-Loop-Helix Transcription Factors/*agonists/*metabolism, Cell Line, Cytochrome P-450 CYP1A1/genetics, Gene Expression, Genes, Genetic, Humans, Indoles, Ligands, Metabolic Networks and Pathways, Mice, Microbiome, Promoter Regions, Protein Binding, Protein Multimerization, Receptors, Reporter, tryptophan, Tryptophan/*metabolism, Tumor},

pubstate = {published},

tppubtype = {article}

}

@article{hyzdalova_aryl_2018,

title = {Aryl Hydrocarbon Receptor-Dependent Metabolism Plays a Significant Role in Estrogen-Like Effects of Polycyclic Aromatic Hydrocarbons on Cell Proliferation.},

author = {Martina Hýžd'alová and Jakub Pivnicka and Ondrej Zapletal and Gerardo Vázquez-Gómez and Jason Matthews and Jirí Neca and Katerina Pencíková and Miroslav Machala and Jan Vondrácek},

doi = {10.1093/toxsci/kfy153},

issn = {1096-0929 1096-6080},

year  = {2018},

date = {2018-10-01},

journal = {Toxicological sciences : an official journal of the Society of Toxicology},

volume = {165},

number = {2},

pages = {447–461},

abstract = {Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants that interact in a complex manner with both the aryl hydrocarbon receptor (AhR) and estrogen receptors (ER). Their potential endocrine-disrupting activities may depend on both inhibitory AhR-ER cross-talk and on AhR-dependent metabolic production of estrogenic PAH metabolites. Here, we analyzed the impact of AhR on estrogen-like effects of PAHs, such as benzo[a]pyrene (BaP), in particular, on control of cell cycle progression/cell proliferation. Using AhR knockout variant of estrogen-sensitive human breast cancer MCF-7 cells (MCF-7 AhRKO cells), we observed that the AhR-dependent control of cytochrome P450 family 1 (CYP1) expression played a major role in formation of estrogenic BaP metabolites, most notably 3-OH-BaP, which contributed to the ER-dependent induction of cell cycle progression/cell proliferation. Both BaP metabolism and the BaP-induced S-phase transition/cell proliferation were inhibited in MCF-7 AhRKO cells, whereas these cells remained sensitive towards both endogenous estrogen 17β-estradiol or hydroxylated BaP metabolites. BaP was found to increase the activity of ER-dependent luciferase reporter gene in wild-type MCF-7 cells; however, unlike its hydroxylated metabolite, BaP failed to stimulate luciferase activity in MCF-7 AhRKO cells. Similarly, estrogen-like effects of other known estrogenic PAHs, such as benz[a]anthracene or 3-methylcholanthrene, were diminished in MCF-7 AhRKO cells. Ectopic expression of human CYP1A1 and CYP1B1 enzymes partly restored both BaP metabolism and its effects on cell proliferation. Taken together, our data suggest that the AhR-dependent metabolism of PAHs contributes significantly to the impact of PAHs on cell proliferation in estrogen-sensitive cells.},

note = {Place: United States},

keywords = {Aryl Hydrocarbon/genetics/*metabolism, Cell Culture Techniques, Cell Cycle/drug effects/genetics, Cell Proliferation/*drug effects/genetics, Cytochrome P-450 CYP1A1/genetics/metabolism, Cytochrome P-450 CYP1B1/genetics/metabolism, Endocrine Disruptors/metabolism/*toxicity, Estrogen/genetics/metabolism, Gene Expression/drug effects, Gene Knockdown Techniques, Genes, Genetic Vectors, Humans, MCF-7 Cells, Plasmids, Polycyclic Aromatic Hydrocarbons/metabolism/*toxicity, Receptors, Reporter, Transfection},

pubstate = {published},

tppubtype = {article}

}

@article{vondracek_assessment_2017,

title = {Assessment of the aryl hydrocarbon receptor-mediated activities of polycyclic aromatic hydrocarbons in a human cell-based reporter gene assay.},

author = {Jan Vondráček and Kateřina Pěnčíková and Jiří Neča and Miroslav Ciganek and Aneta Grycová and Zdeněk Dvořák and Miroslav Machala},

doi = {10.1016/j.envpol.2016.09.064},

issn = {1873-6424 0269-7491},

year  = {2017},

date = {2017-01-01},

journal = {Environmental pollution (Barking, Essex : 1987)},

volume = {220},

number = {Pt A},

pages = {307–316},

abstract = {Activation of the aryl hydrocarbon receptor (AhR)-mediated activity is one of key events in toxicity of polycyclic aromatic hydrocarbons (PAHs). Although various classes of AhR ligands may differentially activate human and rodent AhR, there is presently a lack of data on the human AhR-inducing relative potencies (REPs) of PAHs. Here, we focused on estimation of the AhR-mediated activities of a large set of environmental PAHs in human gene reporter AZ-AhR cell line, with an aim to develop the human AhR-based REP values with potential implications for risk assessment of PAHs. The previously identified weakly active PAHs mostly failed to activate the AhR in human cells. The order for REPs of individual PAHs in human cells largely corresponded with the available data from rodent-based experimental systems; nevertheless, we identified differences up to one order of magnitude in REP values of PAHs between human and rodent cells. Higher REP values were found in human cells for some important environmental contaminants or suspected carcinogens, such as indeno[1,2,3-cd]pyrene, benz[a]anthracene or benzo[b]fluoranthene, while lower REP values were determined for methyl-substituted PAHs. Our results also indicate that a different rate of metabolism for individual PAHs in human vs. rodent cells may affect estimation of REP values in human cell-based assay, and potentially alter toxicity of some compounds, such as benzofluoranthenes, in humans. We applied the AZ-AhR assay to evaluation of the AhR-mediated activity of complex mixtures of organic compounds associated with diesel exhaust particles, and we identified the polar compounds present in these mixtures as being particularly highly active in human cells, as compared with rodent cells. The present data suggest that differences may exist between the AhR-mediated potencies of PAHs in human and rodent cells, and that the AhR-mediated effects of polar PAH derivatives and metabolites in human cell models deserve further attention.},

note = {Place: England},

keywords = {AhR, AhR-mediated activity, Aryl Hydrocarbon/metabolism/*physiology, Basic Helix-Loop-Helix Transcription Factors/metabolism/*physiology, Biological Assay/methods, Carcinogens/toxicity, Cell Line, Environmental Pollutants/*toxicity, Genes, Humans, PAH mixtures, PAHs, Polycyclic Aromatic Hydrocarbons/*toxicity, Receptors, Relative effective potency, Reporter, Vehicle Emissions/toxicity},

pubstate = {published},

tppubtype = {article}

}

@article{davis_effect_2006,

title = {Effect of apple extracts on NF-kappaB activation in human umbilical vein endothelial cells.},

author = {Paul A. Davis and John A. Polagruto and Giuseppe Valacchi and Anh Phung and Karel Soucek and Carl L. Keen and M. Eric Gershwin},

doi = {10.1177/153537020623100514},

issn = {1535-3702 1535-3699},

year  = {2006},

date = {2006-05-01},

journal = {Experimental biology and medicine (Maywood, N.J.)},

volume = {231},

number = {5},

pages = {594–598},

abstract = {The mechanisms by which foods, such as fruit, are able to reduce the risk of chronic disease are still unclear. Several fruit products, including apples and apple juice, that are flavonoid-rich are reported to increase antioxidant levels in human subjects. This is supported by the finding from our previous studies that the chronic consumption of apple juice by human subjects reduced ex vivo low-density lipoprotein (LDL) oxidation; we hypothesized that this was due to the flavonoid in the apple juice, which, as we reported earlier, reduced in vitro LDL oxidation. To further explore whether the mixture of flavonoids and other phytochemicals in apples are biologically relevant antioxidants, we tested the effects of this flavonoid-rich apple extract (AE) on oxidant-related pathways in a model of the endothelium: human umbilical vascular endothelial cells (HU-VECs). The effects of AE on oxidant-responsive (i.e., tumor necrosis factor [TNF]-alpha-induced) nuclear factor (NF)- kappaB signaling in cell culture were assessed in transfected HUVECs by using a construct that expressed luciferase under the control of NF-kappaB. Incubation of HUVEC for 24 hrs with up to 10 mM (as gallic acid equivalents) of AE demonstrated no cytotoxicity, as determined by lactate dehydrogenase release, caspase 3 activation, and apoptosis marker-based FACS analysis. AE after a 24-hr incubation period at either 200 or 2000 nM showed a complex pattern of decreased basal and TNF-alpha-stimulated NF-kappaB signaling (63% maximal decrease) as assessed by luciferase activity in the transfected HUVECs, as well as by reduced levels of IkappaBalpha protein phosphorylation detected by Western blot analysis. We suggest that AE downregulates NF-kappaB signaling and that this is indicative of an antioxidant effect of the flavonoids present in AE.},

note = {Place: Switzerland},

keywords = {Cell Line, Endothelial Cells/cytology/*metabolism, Flavonoids/*metabolism, Genes, Humans, I-kappa B Proteins/metabolism, Malus/*chemistry, NF-kappa B/*metabolism, NF-KappaB Inhibitor alpha, Plant Extracts/*metabolism, Reporter, Umbilical Veins/*cytology},

pubstate = {published},

tppubtype = {article}

}