Benzotriazole Ultraviolet Stabilizers Show Potent ... - ACS Publications

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Benzotriazole Ultraviolet Stabilizers Show Potent Activities as Human Aryl Hydrocarbon Receptor Ligands Haruna Nagayoshi,*,† Kensaku Kakimoto,† Sokichi Takagi,† Yoshimasa Konishi,† Keiji Kajimura,† and Tomonari Matsuda‡ †

Osaka Prefectural Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka, 537-0025, Japan Research Center for Environmental Quality Management, Kyoto University, 1-2 Yumihama, Otsu, 520-0811, Japan

‡

ABSTRACT: Benzotriazole ultraviolet stabilizers (BUVSs) used in consumer products are raising concerns as new pollutants in the aquatic environment. We determined the agonistic activities of eight BUVSs and a chemically distinct UV absorber (4-methylbenzylidinecamphor) toward the human aryl hydrocarbon receptor (AhR) and thyroid hormone receptors alpha and beta. Although none of the BUVSs showed ligand activity against the thyroid hormone receptors, four of them (UV-P, UV-9, UV-326, and UV-090) showed significant AhR ligand activity. Their half-maximal effective concentrations (EC50) were 130 nM for UV-P, 460 nM for UV-9, and 5.1 μM for UV-090 (a value for UV-326 could not be determined). Of the numerous AhR ligands, it is well-known that those considered nontoxic are quickly metabolized by enzymes such as CYP1A1, which destroys their ability to function as ligands. Accordingly, we established a new yeast assay for simultaneous monitoring of both the strength of AhR ligand activity and ligand degradation by CYP1A1. We found the AhR ligand activities of the above four BUVSs to be stable in the presence of CYP1A1; therefore, they have the potential to accumulate and exert potent physiological effects in humans, analogous to polycyclic aromatic hydrocarbons and dioxins, which are known stable and toxic ligands.

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toxicity, persistence in the environment, and bioaccumulation.8 The bioconcentration factors of UV-320 in carp ranged from 1380 to 8180 and 2960 to 10 000 at the exposure levels of 1 μg/L (14 weeks) and 0.1 μg/L (10 weeks), respectively.9 Histopathological changes in rat liver were found following long-term exposure to UV-320.10 For the above reasons, usage, production, and importation of UV-320 have been regulated in Japan since 2007. The Japanese government also classified 2,4di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol (UV-327, CAS Registry No. 3864-99-1) as a Monitoring Chemical Substance since it also showed high bioaccumulative characteristics.8 On the other hand, several BUVSs are still used in Japan. With respect to the bioaccumulation and toxicity of other BUVSs, we are aware of only limited information: a study showing a significant positive relationship between tissue concentration of 2-(benzotriazol-2-yl)-4-methylphenol (UV-P, CAS Registry No. 2440-22-4) and fish length and fish weight and a second reporting no significant acute toxicity of 2-(3-allyl2-hydroxy-5-methylphenyl)-2H-benzotriazole (CAS Registry No. 2170-39-0, UV-9), UV-320, 2-tert-butyl-6-(5-chlorobenzotriazol-2-yl)-4-methylphenol (UV-326, CAS Registry No. 389611-5), UV-327, 2-(benzotriazol-2-yl)-4,6-bis(2-methylbutan-2yl)phenol (UV-328, CAS Registry No. 25973-55-1), 2-

INTRODUCTION Pharmaceutical and personal care products (PPCPs) are a diverse group of chemicals used in many everyday activities, but they are becoming notable as pollutants. PPCPs include therapeutic drugs for humans and livestock, cosmetics, sunscreens, and plastic coatings, among many other substances. As pollutants, PPCPs may enter the aquatic environment either directly via wash-off from the human body and clothes, via wastewater or sewage, or via runoff from farms.1,2 PPCPs have been ubiquitously identified in the environment, and their ecological impact has become a global concern. Molecules in one class of PPCPs, the benzotriazole ultraviolet stabilizers (BUVSs), function as ultraviolet (UV) filters in various plastic products to prevent light-induced degradation and yellowing. In addition, they are also used in personal-hygiene products, including body lotions, creams, shampoos, fragrances, and sunscreens.3 As a result of their widespread use, BUVS contamination of the aquatic environment, including of municipal wastewater, sewage sludge, coastal water, and sediment, has been a growing environmental concern since the scope of the problem was first reported by Nakata et al. in 2009.3−6 In 2013, a series of BUVSs was detected in indoor air dust.7 Regulatory agencies are beginning to act, and one of the BUVSs, 2-(benzotriazol-2-yl)-4,6-di-tertbutylphenol (UV-320, CAS Registry No. 3846-71-7), was classified as a Class I Specified Chemical Substance in Japan (Act on Evaluation of Chemical Substances and Regulation of Their Manufacture, etc.) in 2007 because of its potential © 2014 American Chemical Society

Received: Revised: Accepted: Published: 578

August 12, 2014 October 18, 2014 November 10, 2014 November 10, 2014 dx.doi.org/10.1021/es503926w | Environ. Sci. Technol. 2015, 49, 578−587

Environmental Science & Technology

Article

phenol (UV-9, CAS Registry No. 2170-39-0), 2-(benzotriazol2-yl)-4,6-bis(2-phenylpropan-2-yl)phenol (UV-234, CAS Registry No. 70321-86-7), and 2-[3-(2H-benzotriazol-2-yl)-4hydroxyphenyl]ethyl methacrylate (UV-090, CAS Registry No. 96478-09-0) were purchased from Sigma-Aldrich, and 4MBC was obtained from Alfa Aesar. The structures of the tested BUVSs and 4-MBC are shown in Figure 1. β-

(benzotriazol-2-yl)-4-(2,4,4-trimethylpentan-2-yl)phenol (UV329, CAS Registry No. 3147-75-9), and 2-(benzotriazol-2-yl)-6[[3-(benzotriazol-2-yl)-2-hydroxy-5-(2,4,4-trimethylpentan-2yl)phenyl]methyl]-4-(2,4,4-trimethylpentan-2-yl)phenol (UV360, CAS Registry No. 103597-45-1) in crustaceans.11,12 Among chemical UV filters, it was shown that some benzophenone compounds, another class of UV absorber, have estrogenic activity. Schlumpf et al. reported that benzophenone-3, homosalate, 4-methylbenzylidinecamphor (4-MBC, CAS Registry No. 36861-47-9), octyl methoxycinnamate, and octyldimethyl-p-aminobenzoic acid caused increased proliferation of the human breast cancer cell line MCF-7 and elicited an estrogenic response in a yeast reporter gene assay.13,14 It was also reported that 4-MBC is uterotrophic in immature rats when administered by either subcutaneous injection or oral gavage.13,15 With respect to BUVSs, Japanese scientists evaluated some BUVSs16,17 but found neither estrogen agonistic nor antagonistic activity. In 2014, Fent et al. showed clear antiandrogenic activity for UV-P using a yeast two-hybrid assay.18 However, additional information about the risk to humans posed by BUVSs is not available. There are many types of environmental pollutants that show agonistic activities toward aryl hydrocarbon receptor (AhR) or thyroid hormone receptors (TRs). AhR, which is the nuclear receptor mediating the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polycyclic aromatic hydrocarbons (PAHs), has a variety of ligands, including not only environmental toxicants but also food-derived and other naturally occurring compounds.19,20 The toxicity of AhR agonistic compounds like TCDD or PAHs is wide-ranging, and their effects include carcinogenesis, teratogenesis, and immunotoxicity.21−23 TRs are nuclear receptors and ligand-dependent transcription factors essential for development of the central nervous system in fetal and postnatal periods.24,25 TRs also play important roles in the maintenance of metabolic functions and brain function.26−28 There are two distinct TRs: TRα and TRβ.29 Metabolites of two classes of environmental toxins, hydroxylated PCBs (OH-PCBs) and hydroxylated PBDEs (OHPBDEs), act as TR agonists and have the potential to disrupt the function of the endogenous TR hormones 3,5,3′-triiodo-Lthyronine (T3) and thyroxin (T4).30−33 In addition to human estrogen receptor and androgen receptor, these two classes of nuclear receptor are considered to be important factors in determining whether environmental contaminants have potency as endocrine-disrupting chemicals. In the present study, we evaluated the ligand activities of eight BUVSs and the representative benzophenone 4-MBC as comparative compound against AhR, TRα, and TRβ to assess the potential risk posed by BUVSs to human health. It is well established that many of the AhR ligands that are considered nontoxic are quickly metabolized by phase I metabolizing enzymes like cytochrome P450 1A1 (CYP1A1), limiting their ability to remain active as AhR ligands. Thus, we developed and describe here a new yeast assay that combines simultaneous monitoring of the strength of AhR ligand activity and ligand degradation by CYP1A1.

Figure 1. Structures of the tested benzotriazole UV stabilizers.

Naphthoflavone (β-NF) and 3-methylcholanthrene (3-MC) were obtained from Sigma-Aldrich. Indirubin was purchased from Enzo Life Sciences Inc., and 6-formylindolo[3,2-b]carbazole (FICZ) was purchased from BIOMOL International, L.P. TCDD was purchased from Cambridge Isotope Laboratories Inc. Saccharomyces cerevisiae strain YCM3, which expresses human AhR and AhR nuclear translocator (Arnt; the protein partner of AhR in the functional heterodimeric receptor) complex, was a kind gift from Dr. C. A. Miller III (Tulane University).34 The yeast reporter gene assay systems for AhR (OPU-AhR), TRα (OPU-TRα), and TRβ (OPU-

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EXPERIMENTAL SECTION Materials. All BUVSs and 4-MBC were of the highest available purity. UV-326 was obtained from Wako Pure Chemical (Osaka, Japan). UV-P, UV-327, UV-328, and UV329 were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). 2-(Benzotriazol-2-yl)-4-methyl-6-prop-2-enyl579

dx.doi.org/10.1021/es503926w | Environ. Sci. Technol. 2015, 49, 578−587


Article

(PCR) from a human CYP1A1-containing plasmid construct. PCR was performed with the following primers: 5′-CCCGGTACCAAAAAATGCTTTTCCCAAT-3′ and 5′-GCAGAGCTCCTAAGAGCGCAGCTGCATTT-3′. The forward primer contains a KpnI restriction site and polyA sequence and the reverse primer contains a SacI restriction site. PCR products were cloned with the pGEM-T Easy Kit (Promega) and amplified in Escherichia coli strain DH5α for confirmation by DNA sequencing. The insert was cloned into the KpnI and SacI sites of pBEVY-GL and named pBEVY-GL-CYP1A1 (Figure 2A). The length of the plasmid construct was determined by agarose gel electrophoresis. The plasmid was amplified in DH5α and purified.

TRβ) were kindly provided by Dr. M. Kawanishi (Osaka Prefecture University).35,36 Human cytochrome P450 1A1 (CYP1A1) clone (GenBank accession no. BC023019) was purchased from the American Type Culture Collection through Summit Pharmaceuticals International Corp. (Tokyo, Japan). The bidirectional yeast expression vector pBEVY-GL, with the LEU2 gene as a selection marker, developed by Dr. C. A. Miller III (GenBank accession no. AF069719), was also provided by Dr. M. Kawanishi.37 Other reagents were mainly purchased from Wako Pure Chemical Industries, Ltd. (Osaka, Japan) and were of the highest grade available. Yeast Reporter Gene Assay. The assay procedure was based on methods described previously or the manufacturer’s instructions.36,38 Briefly, a yeast glycerol stock (OPU-AhR, OPU-TRα, and OPU-TRβ) was grown overnight at 30 °C with shaking in synthetic medium consisting of 0.17% yeast nitrogen base (without amino acids and ammonium sulfate), 0.5% ammonium sulfate, 2% D-glucose, and 0.13% amino acids and nucleic acid bases. One microliter of various concentrations of test chemicals dissolved in dimethyl sulfoxide (DMSO), 10 μL of yeast overnight culture, and 90 μL of synthetic medium containing 2% galactose instead of glucose were mixed and incubated at 30 °C for 18 h. AhR, Arnt, TRα, and TRβ cDNA are under the control of the bidirectional GAL1, 10 promoter; therefore, these receptors are expressed when galactose is used as the carbon source. Once a test chemical binds to its target nuclear receptor, the ligand−receptor complex translocates to the nucleus and binds the ligand binding domains of the reporter plasmid introduced into the same yeast cell, namely, the xenobiotic response element for AhR and the thyroid hormone response element for TRs. This in turn activates transcription of the bacterial lac Z reporter gene, introduced downstream of the ligand binding domain. Ten microliters of cell suspension and 90 μL of Z-buffer (60 mM Na2HPO4, 40 mM NaH 2 PO 4 , 1 mM MgCl 2 , 10 mM KCl, 2 mM dithiothreitol, and 0.2% sarcosyl) containing 1 mg/L of onitrophenyl-β-D-galactopyranoside (ONPG) were mixed and incubated for 1 h at 37 °C. Cell density and the amount of onitrophenol produced by β-galactosidase were measured spectrophotometrically at 595 nm (OD595) and 405 nm (OD405), respectively. Intensities of β-galactosidase activity was expressed as a ratio of OD405/OD595. β-NF and L-thyroxin were used for positive controls in each assay batch. The assay principle is basically the same between YCM3 and OPU-AhR, as follows: 5 μL of yeast overnight culture and 200 μL of medium containing 2% galactose and 1 μL of test chemical were mixed for the chemical exposure process. In addition, indirubin was used as a working standard for CYP1A1 when experiments using YCM3 and newly developed YCM3CYP1A1 were conducted. For calculation of the half-maximal effective concentration (EC50) values and other parameters for regression analysis, data were plotted on single-logarithmic charts and fitted using a four-parameter logistic method using by GraphPad Prism version 6.0 for Windows (GraphPad Software, San Diego, CA). Then, the relative intensity for YCM3 and YCM3-CYP1A1 was calculated using the following formula: relative intensity (%) = (OD405/OD595 − a)/(b − a) × 100, where a is the value at concentration 0 and b is the OD405/OD595 value when the concentration is infinite. Each assay was conducted three times. Construction of a Human CYP1A1-Expressing Plasmid. A CYP1A1 coding region that was designed to be expressed in yeast was generated by polymerase chain reaction

Figure 2. (A) Diagram of pBEVY-GL-CYP1A1. (B) Comparison of EROD activities of YCM3 and YCM3-CYP1A1 cultured in medium containing glucose or galactose. N.D., none detected.

Establishment of a New Yeast Reporter Gene Assay To Evaluate the Effect of Human CYP1A1 on AhR Ligand Activity. S. cerevisiae YCM3 cells were transformed with pBEVY-GL-CYP1A1 using a high-efficiency lithium acetate method.39 The transformed yeasts were inoculated onto agar plates without leucine. After 3 days of incubation at 30 °C, a randomly selected colony was named YCM3-CYP1A1. We measured the 7-ethoxyresorufin o-deethylation (EROD) activity of YCM3-CYP1A1 after induction of human CYP1A1 by growing the cells in synthetic medium with galactose. YCM3 and YCM3-CYP1A1 were grown in synthetic minimal medium overnight at 30 °C with shaking. A 100-μL aliquot of culture was suspended in 4 mL of minimal synthetic medium containing 2% glucose or galactose and grown overnight at 30 °C with shaking. Cell cultures were centrifuged and resuspended in 1 mL of sterilized water, and the cell density was measured by OD at 595 nm (OD595). The following procedure was based partly on a method by Nthangeni et al.40 The cells were centrifuged again and resuspended in reaction buffer containing 50 mM Tris-HCl (pH 7.5) and 1 mM EDTA at a concentration of 3.0 × 107 cells/mL (the OD595 value was approximately 0.9). Fifty microliters of cell suspension was prewarmed at 37 °C and the CYP1A1 enzymatic reaction was started by addition of 1 μL of 1 mM 7-ethoxyresorufin methanol solution. After 60 min of incubation at 37 °C, the reaction was stopped by adding 50 μL of ice-cold methanol, and then yeast cells were removed by centrifugation. The amount of resorufin in the supernatant was determined by highperformance liquid chromatography according to the procedure of Hanioka et al.41 Each assay was conducted three times.

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RESULTS AND DISCUSSION Ligand Activities of BUVSs toward human AhR, TRα, and TRβ. In this study, we examined the agonistic activity of 580



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Figure 3. Agonistic activity of eight BUVSs and 4-MBC against AhR, TRα, and TRβ was determined. Each plot indicates UV-P (■), UV-9 (●), UV234 (△), UV-326 (×), UV-327 (▲), UV-328 (□), UV-329 (○), UV-090 (◆), and 4-MBC (□). β-NF for AhR and L-thyroxin for TRs were utilized as positive controls, and they were plotted using the symbol ◇. Error bars show the standard deviation of each test. OPU-AhR, OPU-TRα, and OPU-TRβ strains were used for this experiment.

Table 1. Parameters for Regression Analysis and Intensities of AhR Activity of BUVSsa compd

a

b

c

R2

EC50 (nM)

95% confidence interval of EC50 (nM)

ratio

β-NF UV-P UV-9 UV-090 UV-326 β-NFb TCDDb

3.2 2.8 2.9 2.5 NC − −

33 30 34 24 NC − −

1.07 1.94 1.56 1.37 NC − −

0.975 0.972 0.998 0.952 NC − −

17 130 460 5.1 × 103 NC 7 10

11−26 82−210 410−520 (3.3−8.0) × 103 NC − −

1 7.8 28 307 NC 1 1.5

a OD405/OD595 values were plotted on single-logarithmic charts and fitted using a four-parameter logistic method using the following formula: OD405/OD595 = a + (b − a)/(1 + 10(logEC50‑concn)c), where a is the value at concentration 0, b is the OD405/OD595 value at infinity, and c is the regression curve factor. R2 is the coefficient of determination of the regression curve. The ratio was calculated by the formula (EC50 of each compound)/(EC50 of β-NF). NC means not calculated. bData were taken from Kawanishi et al.35

activity.35 Overall, we identified four BUVSs as being new human AhR ligands. On the other hand, 4-MBC, an estrogenic UV filter, did not show AhR agonistic activity; therefore, we infer that the behaviors in the human body are different between benzophenones and benzotriazoles. Recently, Fent et al. reported that UV-P and UV-326 cause transcriptional alteration of the AhR pathway in zebrafish eleuthero-embryos.18 The function of AhR is well-conserved in vertebrates; therefore, UV-P and UV-326 likely function as agonists in zebrafish. As far as we know, our study is the first to report the potential of BUVSs as human AhR agonists. Producers and suppliers of BUVSs now exist globally, including in Europe, Asia, and America. Annual production volumes of each BUVS are reported by the National Toxicology Program in the United States, the Swedish Environmental Research Institute, and the National Institute of Technology and Evaluation Japan. Focusing on AhR agonistic BUVSs, the production volumes of UV-P and UV-326 in the United States were approximately 450 tonnes each in 2006.42 In Sweden, UVP usage was around 40 tonnes in 2008.43 Lastly, Japanese usage

BUVSs toward AhR, TRα, and TRβ with yeast strains OPUTRα, OPU-TRβ, and OPU-AhR. As shown in Figure 3, none of the BUVSs exhibited agonistic activities toward TRα and TRβ. However, the compounds UV-P, UV-9, UV-326, and UV-090 all significantly activated AhR. EC50 values and their 95% confidence intervals are shown in Table 1 as follows: 130 nM (95% confidence interval of EC50, 83−210 nM) for UV-P, 460 nM (410−520 nM) for UV-9, and 5.1 μM (3.3−8.0 μM) for UV-090. In the case of UV-326, we could not determine its EC50 because its ligand activity did not plateau. The OD405/ OD595 value of UV-090 did not achieve a plateau either, but a reasonable value was estimated from its R2 value (close to 1) obtained from curve-fitting analysis. Table 1 also shows the ratio of EC50 values of BUVSs to that of β-NF, a potent AhR agonist. The strengths of the AhR agonistic activities of BUVSs were 7.8 (UV-P), 28 (UV-9), and 307 (UV-090) times weaker than that of β-NF. In the case of TCDD, the strength of its AhR activity was reported to be only 1.5 times weaker than that of β-NF.35 Comparing the results of a previous report and this study, UV-P can be considered a potent AhR agonist, whereas UV-9 and UV-090 showed 2 or 3 orders of magnitude weaker 581



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Figure 4. Changes in AhR ligand activity in the presence of CYP1A1 were determined in two yeast strains, YCM3 (●) and YCM3-CYP1A1 (□). Relative intensities were calculated by using the following formula: relative intensity (%) = (OD405/OD595 − a)/(b − a) × 100, where a is the OD405/OD595 value at concentration 0 and b is the OD405/OD595 value when the concentration is infinite. Parameters calculated by the fourparameter logistic method are shown in Table 2. Error bars show the standard deviation of each test.

Establishment of a Combined Monitoring System To Classify Toxic and Nontoxic AhR Ligands. We sought to develop a new system for estimating the toxic potential of AhR ligand candidates while taking into account degradation of ligand activity by metabolism. For screening of AhR ligand activity, we used OPU-AhR because the OPU series of strains is isogenic and therefore well-suited for comparing ligand activity among strains. However, modification of OPU-AhR is not permitted because of patent licensing. Therefore, we selected the S. cerevisiae reporter gene strain YCM3 as the platform for the assay system because, like OPU-AhR, it expresses human AhR and Arnt under the control of the GAL1, 10 promoter and possesses no metabolic enzymes corresponding to AhR-related ones like CYP1A1. First, we constructed an expression plasmid containing full-length CYP1A1, named pBEVY-GL-CYP1A1 (Figure 2A), which was then used to transform YCM3 to produce the strain YCM3-CYP1A1. In this new system, expression of human CYP1A1 should be activated in the presence of galactose in the same manner as AhR and Arnt. The enzymatic activity of CYP1A1 in this strain was determined by measuring EROD activity. As shown in Figure 2B, when YCM3-CYP1A1 was cultured with the inducer galactose, EROD activity was significantly increased (to 73.8 ± 16.4 pM/min/OD595) compared to that of

of UV-326 was around 1000 tonnes per year from 2010 to 2013.8 BUVSs are also reported to be widespread contaminants in aquatic environments and marine organisms. For example, UV326 and UV-P concentrations ranged from 0.5 to 110 ng/g dry weight and from 0.5 to 15 ng/g dry weight, respectively, in river sediment in Japan, China, and the United States.3,6,44 In tidal sediment, UV-326 was more concentrated, ranging from 23 to 200 ng/g dry weight.3 UV-326 was also found in marine organisms of the Ariake Sea, Japan, at concentrations ranging from not detected (ND) to 5.6 ng/g wet weight,3 and in Manila Bay, UV-326, UV-P, and UV-9 concentrations ranged from ND to 71.3, ND to 222, and ND to 16.2 ng/g lipid weight.11,45 BUVSs have also been detected in indoor dust. Kim et al. reported UV-326 in house dust at concentrations of ND to 275 ng/g dry weight in the Philippines.7 Carpinteiro et al. reported UV-326 and UV-P concentrations on indoor dust in Spain ranging from 42 to 4883 ng/g dry weight and 65 to 657 ng/g dry weight, respectively.46 Clearly, humans are at risk of exposure to AhR agonistic BUVSs such as UV-326, UV-P, UV9, and UV-090 by way of indoor dust and consumed fish. Further studies to elucidate the levels and consequences of human exposure to BUVSs should be required. 582



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Table 2. Parameters for Regression Analysis and Comparison of EC50 Values between YCM3 and YCM3-CYP1A1a compd

a

b

c

R2

EC50 (nM)

95% confidence interval of EC50 (nM)

ratio

YCM3 β-NF indirubin FICZ B[a]P 3-MC TCDD

3.0 0.60 0.50 0.66 0.76 0.81

18 6.3 6.1 6.8 6.0 4.2

1.46 0.948 0.888 0.960 2.00 1.13

0.964 0.973 0.952 0.990 0.992 0.994

UV-P UV-9 UV-090

1.8 1.3 1.1

14 17 14

1.12 1.15 1.65

24−85 130−280 (0.74−3.6) × 103

β-NF indirubin FICZ B[a]P 3-MC TCDD

0.95 1.0 1.7 0.99 1.1 1.2

20 11 10 10 9.3 5.8

1.70 1.54 1.66 1.10 1.68 2.02

0.930 45 0.978 190 0.913 1.6 × 103 YCM3-CYP1A1 0.977 2.6 0.993 9.0 0.995 2.5 0.993 120 0.995 92 0.996 11

1.7−4.0 7−12 2.0−3.0 40−360 74−110 8.9−14

1.8 25 3.5 1.7 1.3 1.0

UV-P UV-9 UV-090

1.0 0.98 0.91

17 16 13

3.44 1.62 1.89

0.990 0.974 0.984

3−130 94−223 (0.66−1.6) × 103

1.4 0.8 0.6

1.4 0.36 0.70 70 72 11

62 140 1.0 × 103

0.81−2.3 0.22−0.60 0.35−1.4 41−120 52−100 9.1−14

a OD405/OD595 values were plotted on single-logarithmic charts and fitted using a four-parameter logistic method using the following formula: OD405/OD595 = a + (b − a)/(1 + 10(logEC50−concn)c), where a is the value at concentration 0, b is the OD405/OD595 value at infinity, and c is the regression curve factor. R2 is the determination coefficient of the regression curve. The ratio is calculated by the formula ratio = (EC50 of YCM3CYP1A1)/(EC50 of YCM3).

was observed between the two strains. In the case of rapidly metabolized ligands, the β-galactosidase activities induced by indirubin and FICZ were significantly decreased in YCM3CYP1A1 compared to YCM3: the EC50 values changed from 0.36 to 9.0 nM (25-fold increase) for indirubin and from 0.7 to 2.5 nM (3.5-fold increase) for FICZ when functional CYP1A1 was expressed. As shown in Table 2, the EC50 95% confidence intervals do not overlap between YCM3 and YCM3-CYP1A1 for indirubin and FICZ. In contrast, significant changes of EC50 were not observed for B[a]P, 3-MC, and TCDD. As shown in Table 2, the EC50 values changed from 70 to 120 nM for B[a]P (1.7-fold increase) and from 72 to 92 nM for 3-MC (1.3-fold increase) and remained stable at 11 nM in the case of TCDD. Moreover, the EC50 95% confidence intervals for B[a]P and 3MC overlap, different from indirubin and FICZ; therefore, we consider that the EC50 of the pollution-originating ligands is not changed between YCM3 and YCM3-CYP1A1. As mentioned above, comparison of the EC50 values and their 95% confidence intervals between two strains should adequately demonstrate whether their AhR ligand activities are transient or continuous in vivo. But it should also be necessary to describe precisely the stability of BUVSs in the human body, such as by evaluating AhR ligand activity after metabolism by liver microsomes or S9 fraction, because AhR ligands are metabolized by other AhRinducible metabolic enzymes such as CYP1A2 and CYP1B1.50 Nonetheless, our methodology can clearly distinguish transient ligands among novel AhR ligand candidates, and it should be a good screening tool to classify the stability of AhR ligand candidates. Effect of CYP1A1 on AhR Ligand Activity of BUVSs. Elucidating the effect of metabolism by CYP1A1 on the strength of newly identified AhR ligands should be useful for classifying their toxic potential. Therefore, we investigated

YCM3-CYP1A1 cultured in glucose-containing medium (p < 0.01 by Student’s t test). Although a slight amount of EROD activity was also detected in YCM3 cultured with galactose, this activity was at least 5 times lower than for YCM3-CYP1A1. Thus, we confirmed that YCM3-CYP1A1 is able to express a significant amount of human CYP1A1 in an active form when the strain is cultured in medium containing galactose as the carbon source. As a result, we successfully established an advanced yeast reporter gene assay that is able to evaluate AhR ligand activity of the compound while taking into account the effect of CYP1A1. AhR has a variety of ligands that includes not only environmental toxicants but also food-derived molecules, such as flavonoids, and biosynthetic products.19,20 Biosynthetic strong AhR ligands include tryptophan-related compounds such as indirubin, isolated from human urine, and FICZ, a photosynthetic product of tryptophan.38,47 Indirubin and FICZ are known to activate AhR transiently and they lose their ligand activity within 24 h.47,48 Additionally, they are considered as nontoxic compounds because of their rapid metabolism by AhR-inducible enzymes such as CYP1A1.48,49 We reasoned that the rate of decline in AhR activity mediated by CYP1A1 activity would be a good predictor of the bioaccumulation potential of an AhR ligand. Therefore, we compared the AhR activities of several rapidly metabolized and non- or slowly metabolized ligands between YCM3 and the newly developed YCM3CYP1A1 strain so as to check the latter’s ability for estimating the speed of degradation of AhR ligands. The relative intensities of the AhR ligand activity of each chemical between YCM3 and YCM3-CYP1A1, reflected by β-galactosidase reporter activity, are shown in Figure 4. In addition, parameters for the data fitting and comparison of EC50 values are summarized in Table 2. First, in the case of β-NF, only a slight difference in activity 583



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Figure 5. Changes in the AhR ligand activity of UV-P, UV-9, and UV-090 in the presence of CYP1A1 metabolism was determined in two yeast strains, YCM3 (●) and YCM3-CYP1A1 (□). Relative intensities were calculated by using the following formula: relative intensity (%) = (OD405/ OD595 − a)/(b − a) × 100, where a is the OD405/OD595 value at concentration 0 and b is the OD405/OD595 value when the concentration is infinite. Parameters calculated by the four-parameter logistic method are shown in Table 2. Error bars show the standard deviation of each test.

immune-responsive cytokines have been reported.58−61 Several studies compared the immune responses induced by the most stable AhR ligand, TCDD, and the endogenous ligand FICZ. Wheeler et al. showed that TCDD enhanced the immune response of mice to infection by influenza A virus (e.g., by promoting pulmonary neutrophilia, expression of inducible nitric oxide synthase levels in the lung, and differentiation of virus-specific CD8+ cytotoxic T lymphocytes62). On the other hand, mice treated with FICZ did not show any changes.62 However, the same immune-response changes were observed when FICZ was administered to CYP1A1-deficient mice.62 Nguyen et al. reported that FICZ and TCDD promoted and suppressed, respectively, experimental autoimmune encephalomyelitis, because FICZ enhanced the differentiation of CD4+ T lymphocytes expressing IL-17 and TCDD promoted differentiation of Foxp3+ regulatory T cells in the thymus.63 Quintana et al. argued that such different responses derive from the molecular stability of exogenous and endogenous compounds.64 Therefore, chemical stability against CYP1A1 metabolism is suspected to play important roles in the mechanisms of the immunological responses related to AhR activation. In this study, we found that the strengths of the AhR ligand activities of UV-P, UV-9, and UV-090 were not changed by the presence of CYP1A1. This indicates that BUVSs may act in the same way as TCDD on the human immune system. As mentioned above, BUVS contamination of both aquatic (including seafood) and terrestrial (indoor dust) environments appears to be widespread.7,11,45,46 Consequently, there is a high likelihood that the general human population will be exposed to AhR-activating BUVSs and that these compounds could adversely affect the immune response, just as other environmental toxicants such as dioxins do. Further study of human exposure, physiological effects, metabolism, and excretion of BUVSs is required.

whether the AhR ligand activity of three BUVSs (UV-P, UV-9, and UV-090) was changed in the presence of CYP1A1 by comparing ligand activity in YCM3 versus YCM3-CYP1A1 as described above. We also assessed β-NF as a nonmetabolized positive control and indirubin as a typical metabolized positive control for confirmation of CYP1A1 activity in each experimental batch. As shown in Figure 5 and Table 2, no significant changes in β-galactosidase activities were observed for the three BUVSs (UV-P, UV-9, and UV-090). The EC50 values in YCM3 were approximately 45 nM (95% confidence interval, 24−85 nM) for UV-P, 190 μM for UV-9 (130−280 nM), and 1.6 μM (0.74−3.6 μM) for UV-090. The EC50 values in YCM3-CYP1A1 were approximately 62 nM (3−130 nM) for UV-P, 140 nM (94−223 nM) for UV-9, and 1.0 μM (0.66−1.6 μM) for UV-090. The EC50 values tested by YCM3-CYP1A1 increased 1.4-fold for UV-P, 0.8-fold for UV-9 and 0.6-fold for UV-090. As shown in Table 2, their 95% confidence intervals overlap between YCM3 and YCM3-CYP1A1. Therefore, we conclude that UV-P, UV-9, and UV-090, newly identified AhR agonists, are not actively metabolized by CYP1A1, and as a result, they will tend to be stable in the human body, that is, there is a possibility that they will accumulate in the body and have adverse effects on human health. AhR agonistic activities are observed in numerous environmental pollutants, including dioxins and PAHs. There are numerous reports describing how activated AhR combined with other transcription factors can have various physiological effects, including induction of xenobiotic-metabolizing enzymes, altered cell-cycle regulation, and production of reactive oxygen species.51−54 Recently, connections between AhR activation and the immune system have been vigorously discussed.55−57 The role of AhR in the immune system varies widely in both proinflammatory and anti-inflammatory responses and depends on factors such as cell type and the disease; for example, promotion of T-cell differentiation, suppression of dendritic cell activity, and induction of 584



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tandem mass spectrometry. Chemosphere 2011, 85 (5), 751−758 DOI: 10.1016/j.chemosphere.2011.06.054. (12) Kim, J. W.; Chang, K. H.; Isobe, T.; Tanabe, S. Acute toxicity of benzotriazole ultraviolet stabilizers on freshwater crustacean (Daphnia pulex). J. Toxicol.Sci. 2011, 36, 247−251 DOI: 10.2131/jts.36.247. (13) Schlumpf, M.; Cotton, B.; Conscience, M.; Haller, V.; Steinmann, B.; Lichtensteiger, W. In vitro and in vivo estrogenicity of UV screens. Environ. Health Perspect. 2001, 109 (3), 239−244. (14) Schlumpf, M.; Kypke, K.; Wittassek, M.; Angerer, J.; Mascher, H.; Mascher, D.; Vökt, C.; Birchler, M.; Lichtensteiger, W. Exposure patterns of UV filters, fragrances, parabens, phthalates, organochlor pesticides, PBDEs, and PCBs in human milk: Correlation of UV filters with use of cosmetics. Chemosphere 2010, 81 (10), 1171−1183 DOI: 10.1016/j.chemosphere.2010.09.079. (15) Tinwell, H.; Lefevre, P. A.; Moffat, G. J.; Burns, A.; Odum, J.; Spurway, T. D.; Orphanides, G.; Ashby, J. Confirmation of uterotrophic activity of 3-(4-methylbenzylidine)camphor in the immature rat. Environ. Health Perspect. 2002, 110 (5), 533−536. (16) Kawamura, Y.; Ogawa, Y.; Nishimura, T.; Kikuchi, Y.; Nishikawa, J. I.; Nishihara, T.; Tanamoto, K. Estrogenic activities of UV stabilizers used in food contact plastics and benzophenone derivatives tested by the yeast two-hybrid assay. J. Health Sci. 2003, 49 (3), 205−212 DOI: 10.1248/jhs.49.205. (17) Morohoshi, K.; Yamamoto, H.; Kamata, R.; Shiraishi, F.; Koda, T.; Morita, M. Estrogenic activity of 37 components of commercial sunscreen lotions evaluated by in vitro assays. Toxicol. In Vitro 2005, 19 (4), 457−469 DOI: 10.1016/j.tiv.2005.01.004. (18) Fent, K.; Chew, G.; Li, J.; Gomez, E. Benzotriazole UVstabilizers and benzotriazole: Antiandrogenic activity in vitro and activation of aryl hydrocarbon receptor pathway in zebrafish eleutheroembryos. Sci. Total Environ. 2014, 482−483, 125−136 DOI: 10.1016/ j.scitotenv.2014.02.109. (19) Zhang, S.; Qin, C.; Safe, S. H. Flavonoids as aryl hydrocarbon receptor agonists/antagonists: Effects of structure and cell context. Environ. Health Perspect. 2003, 111 (16), 1877−1882 DOI: 10.1289/ ehp.6322. (20) Denison, M. S.; Nagy, S. R. Activation of the aryl hydrocarbon receptor by structurally diverse exogenous and endogenous chemicals. Annu. Rev. Pharmacol. Toxicol. 2003, 43, 309−334 DOI: 10.1146/ annurev.pharmtox.43.100901.135828. (21) Fernandez-Salguero, P. M.; Hilbert, D. M.; Rudikoff, S.; Ward, J. M.; Gonzalez, F. J. Aryl-hydrocarbon receptor-deficient mice are resistant to 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced toxicity. Toxicol. Appl. Pharmacol. 1996, 140 (1), 173−179 DOI: 10.1006/ taap.1996.0210. (22) Gonzalez, F. J.; Fernandez-Salguero, P. The aryl hydrocarbon receptor: Studies using the AHR-null mice. Drug Metab. Dispos. 1998, 26 (12), 1194−1198. (23) Mimura, J.; Yamashita, K.; Nakamura, K.; Morita, M.; Takagi, T. N.; Nakao, K.; Ema, M.; Sogawa, K.; Yasuda, M.; Katsuki, M.; FujiiKuriyama, Y. Loss of teratogenic response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in mice lacking the Ah (dioxin) receptor. Genes Cells 2003, 2 (10), 645−654 DOI: 10.1046/j.13652443.1997.1490345.x. (24) Evans, R. The steroid and thyroid hormone receptor superfamily. Science 1988, 240 (4854), 889−895 DOI: 10.1126/ science.3283939. (25) Zhang, J.; Lazar, M. A. The mechanism of action of thyroid hormones. Annu. Rev. Physiol. 2000, 62, 439−466 DOI: 10.1146/ annurev.physiol.62.1.439. (26) Mullur, R.; Liu, Y. Y.; Brent, G. A. Thyroid hormone regulation of metabolism. Physiol. Rev. 2014, 94, 355−382 DOI: 10.1152/ physrev.00030.2013. (27) Remaud, S.; Gothié, J. D.; Morvan-Dubois, G.; Demeneix, B. A. Thyroid hormone signaling and adult neurogenesis in mammals. Front. Endocrinol. 2014, 5 (62), 1−7 DOI: 10.3389/fendo.2014.00062. (28) Schroeder, A. C.; Privalsky, M. L. Thyroid hormones, T3 and T4, in the brain. Front. Endocrinol. 2014, 5 (40), 1−6 DOI: 10.3389/ fendo.2014.00040.

AUTHOR INFORMATION

Corresponding Author

*Phone: +81-6-6972-1321. Fax: +81-6-6972-2393. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS

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REFERENCES

This work was supported in part by MEXT KAKENHI Grant Number 16201012. We thank Dr. Masanobu Kawanishi of Osaka Prefectural University and Dr. Charles A. Miller III of Tulane University for providing the yeast strains.

(1) Boxall, A. B.; Rudd, M. A.; Brooks, B. W.; Caldwell, D. J.; Choi, K.; Hickmann, S.; Innes, E.; Ostapyk, K.; Staveley, J. P.; Verslycke, T.; Ankley, G. T.; Beazley, K. F. Review pharmaceuticals and personal care products in the environment: What are the big questions ? Environ. Health Perspect. 2012, 120 (9), 1221−1229 DOI: 10.1289/ ehp.1104477. (2) Brausch, J. M.; Rand, G. M. A review of personal care products in the aquatic environment: Environmental concentrations and toxicity. Chemosphere 2011, 82 (11), 1518−1532 DOI: 10.1016/j.chemosphere.2010.11.018. (3) Nakata, H.; Murata, S.; Filatreau, J. Occurrence and concentrations of benzotriazole UV stabilizers in marine organisms and sediments from the Ariake Sea, Japan. Environ. Sci. Technol. 2009, 43 (18), 6920−6926 DOI: 10.1021/es900939j. (4) Montesdeoca-Esponda, S.; Sosa-Ferrera, Z.; Santana-Rodríguez, J. J. On-line solid-phase extraction coupled to ultra-performance liquid chromatography with tandem mass spectrometry detection for the determination of benzotriazole UV stabilizers in coastal marine and wastewater samples. Anal. Bioanal. Chem. 2012, 403 (3), 867−876 DOI: 10.1007/s00216-012-5906-x. (5) Stasinakis, A. S.; Thomaidis, N. S.; Arvaniti, O. S.; Asimakopoulos, A. G.; Samaras, V. G.; Ajibola, A.; Mamais, D.; Lekkas, T. D. Contribution of primary and secondary treatment on the removal of benzothiazoles, benzotriazoles, endocrine disruptors, pharmaceuticals and perfluorinated compounds in a sewage treatment plant. Sci. Total Environ. 2013, 463−464, 1067−1075 DOI: 10.1016/ j.scitotenv.2013.06.087. (6) Zhang, Z.; Ren, N.; Li, Y. F.; Kunisue, T.; Gao, D.; Kannan, K. Determination of benzotriazole and benzophenone UV filters in sediment and sewage sludge. Environ. Sci. Technol. 2011, 45 (9), 3909−3916 DOI: 10.1021/es2004057. (7) Kim, J. W.; Isobe, T.; Malarvannan, G.; Sudaryanto, A.; Chang, K. H.; Prudente, M.; Tanabe, S. Contamination of benzotriazole ultraviolet stabilizers in house dust from the Philippines: Implications on human exposure. Sci. Total Environ. 2012, 424 (1), 174−181 DOI: 10.1016/j.scitotenv.2012.02.040. (8) National Institute of Technology and Evaluation−Japan CHEmicals Collaborative Knowledge database (J-CHECK) Website; http://www.safe.nite.go.jp/jcheck/List6Action?category= 211&request_locale=en. (9) National Institute of Technology and Evaluation Chemical Risk Information Platform (CHIRP) Website; http://www.safe.nite.go.jp/ english/sougou/view/ComprehensiveInfoDisplay_en.faces. (10) Hirata-Koizumi, M.; Ogata, H.; Imai, T.; Hirose, A.; Kamata, E.; Ema, M. A 52-week repeated dose toxicity study of ultraviolet absorber 2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)benzotriazole in rats. Drug Chem. Toxicol. 2008, 31 (1), 81−96 DOI: 10.1080/ 01480540701688758. (11) Kim, J. W.; Isobe, T.; Ramaswamy, B. R.; Chang, K. H.; Amano, A.; Miller, T. M.; Siringan, F. P.; Tanabe, S. Contamination and bioaccumulation of benzotriazole ultraviolet stabilizers in fish from Manila Bay, the Philippines using an ultra-fast liquid chromatography− 585



Article

(29) Lazar, M. A.; Chin, W. W. Nuclear thyroid hormone receptors. J. Clin. Invest. 1990, 86 (6), 1777−1782 DOI: 10.1172/JCI114906. (30) Amano, I.; Miyazaki, W.; Iwasaki, T.; Shimokawa, N.; Koibuchi, N. The effect of hydroxylated polychlorinated biphenyl (OH-PCB) on thyroid hormone receptor (TR)-mediated transcription through native-thyroid hormone response element (TRE). Ind. Health 2010, 48 (1), 115−118 DOI: 10.2486/indhealth.48.115. (31) Cantón, R. F.; Sanderson, J. T.; Nijmeijer, S.; Bergman, A.; Letcher, R. J.; Van Den Berg, M. In vitro effects of brominated flame retardants and metabolites on CYP17 catalytic activity: A novel mechanism of action? Toxicol. Appl. Pharmacol. 2006, 216 (2), 274− 281 DOI: 10.1016/j.taap.2006.05.007. (32) Li, F.; Xie, Q.; Li, X.; Li, N.; Chi, P.; Chen, J.; Wang, Z.; Hao, C. Hormone activity of hydroxylated polybrominated diphenyl ethers on human thyroid receptor-beta: In vitro and in silico investigations. Environ. Health Perspect. 2010, 118 (5), 602−606 DOI: 10.1289/ ehp.0901457. (33) Zhou, T.; Taylor, M. M.; Devito, M. J.; Crofton, K. M. Developmental exposure to brominated diphenyl ethers results in thyroid hormone disruption. Toxicol. Sci. 2002, 66 (1), 105−116 DOI: 10.1093/toxsci/66.1.105. (34) Miller, C. A. A human aryl hydrocarbon receptor signaling pathway constructed in yeast displays additive responses to ligand mixtures. Toxicol. Appl. Pharmacol. 1999, 160 (3), 297−303 DOI: 10.1006/taap.1999.8769. (35) Kawanishi, M.; Ohnisi, K.; Takigami, H.; Yagi, T. Simple and rapid yeast reporter bioassay for dioxin screening: Evaluation of the dioxin-like compounds in industrial and municipal waste incineration plants. Environ. Sci. Pollut. Res. Int. 2013, 20 (5), 2993−3002 DOI: 10.1007/s11356-012-1214-4. (36) Shiizaki, K.; Asai, S.; Ebata, S.; Kawanishi, M.; Yagi, T. Establishment of yeast reporter assay systems to detect ligands of thyroid hormone receptors alpha and beta. Toxicol. In Vitro 2010, 24 (2), 638−644 DOI: 10.1016/j.tiv.2009.10.001. (37) Miller, C. A. Assessment of aryl hydrocarbon receptor complex interactions using pBEVY plasmids: Expressionvectors with bidirectional promoters for use in Saccharomyces cerevisiae. Nucleic Acids Res. 1998, 26 (15), 3577−3583 DOI: 10.1093/nar/26.15.3577. (38) Adachi, J.; Mori, Y.; Matsui, S.; Takigami, H.; Fujino, J.; Kitagawa, H.; Miller, C. A.; Kato, T.; Saeki, K.; Matsuda, T. Indirubin and indigo are potent aryl hydrocarbon receptor ligands present in human urine. J. Biol. Chem. 2001, 276 (34), 31475−31478 DOI: 10.1074/jbc.C100238200. (39) Gietz, R. D.; Woods, R. A. Transformation of yeast by lithium acetate/single-stranded carrier DNA/polyethylene glycol method. Methods Enzymol. 2002, 350, 87−96 DOI: 10.1016/S0076-6879(02) 50957-5. (40) Nthangeni, M. B.; Urban, P.; Pompon, D.; Smit, M. S.; Nicaud, J. M. The use of Yarrowia lipolytica for the expression of human cytochrome P450 CYP1A1. Yeast 2004, 21 (7), 583−592 DOI: 10.1002/yea.1127. (41) Hanioka, N.; Tatarazako, N.; Jinno, H.; Arizono, K.; Ando, M. Determination of cytochrome P450 1A activities in mammalian liver microsomes by high-performance liquid chromatography with fluorescence detection. J. Chromatogr. B. Biomed. Sci. Appl. 2000, 744 (2), 399−406 DOI: 10.1016/S0378-4347(00)00278-4. (42) Chemical Information Review Document for Phenolic Benzotriazole. Supporting Nomination for Toxicological Evaluation by the National Toxicology Program; United States National Toxicology Program: Research Triangle Park, NC, 2011; http://ntp.niehs.nih.gov/ntp/ noms/support_docs/phenolicbenzotriazoles_cird_oct2011_508.pdf. (43) Screening of Benzothiazoles, Benzenediamines, Dicyclohexylamine and Benzotriazoles 2009; Report Number B2023; IVL Swedish Environmental Research Institute Ltd.: Stockholm, 2011; http:// www.ivl.se/download/18.3175b46c133e617730d80009737/ 1350484316250/B2023.pdf. (44) Kameda, Y.; Kimura, K.; Miyazaki, M. Occurrence and profiles of organic sun-blocking agents in surface waters and sediments in

Japanese rivers and lakes. Environ. pollut. 2011, 159, 1570−1576 DOI: 10.1016/j.envpol.2011.02.055. (45) Kim, J. W.; Ramaswamy, B. R.; Chang, K. H.; Isobe, T.; Tanabe, S. Multiresidue analytical method for the determination of antimicrobials, preservatives, benzotriazole UV stabilizers, flame retardants and plasticizers in fish using ultra high performance liquid chromatography coupled with tandem mass spectrometry. J. Chromatogr. A 2011, 1218 (22), 3511−3520 DOI: 10.1016/ j.chroma.2011.04.006. (46) Carpinteiro, I.; Abuín, B.; Rodríguez, I.; Ramil, M.; Cela, R. Pressurized solvent extraction followed by gas chromatography tandem mass spectrometry for the determination of benzotriazole light stabilizers in indoor dust. J. Chromatogr. A 2010, 1217, 3729− 3735 DOI: 10.1016/j.chroma.2010.04.022. (47) Oberg, M.; Bergander, L.; Håkansson, H.; Rannug, U.; Rannug, A. Identification of the tryptophan photoproduct 6-formylindolo[3,2b]carbazole, in cell culture medium, as a factor that controls the background aryl hydrocarbon receptor activity. Toxicol. Sci. 2005, 85 (2), 935−943 DOI: 10.1093/toxsci/kfi154. (48) Adachi, J.; Mori, Y.; Matsui, S.; Matsuda, T. Comparison of gene expression patterns between 2,3,7,8-tetrachlorodibenzo-p-dioxin and a natural arylhydrocarbon receptor ligand, indirubin. Toxicol. Sci. 2004, 80 (1), 161−169 DOI: 10.1093/toxsci/kfh129. (49) Wei, Y. D.; Helleberg, H.; Rannug, U.; Rannug, A. Rapid and transient induction of CYP1A1 gene expression in human cells by the tryptophan photoproduct 6-formylindolo[3,2-b]carbazole. Chem. Biol. Interact. 1998, 110 (1−2), 39−55 DOI: 10.1016/S0009-2797(97) 00111-7. (50) Nebert, D. W.; Dalton, T. P.; Okey, A. B.; Gonzalez, F. J. Role of aryl hydrocarbon receptor-mediated induction of the CYP1 enzymes in environmental toxicity and cancer. J. Biol. Chem. 2004, 279, 23847−23850 DOI: 10.1074/jbc.R400004200. (51) Mimura, J.; Fujii-Kuriyama, Y. Functional role of AhR in the expression of toxic effects by TCDD. Biochem. Biophys. Acta 2003, 1619 (3), 263−268 DOI: 10.1016/S0304-4165(02)00485-3. (52) Nebert, D. W.; Roe, A. L.; Dieter, M. Z.; Solis, W. A.; Yang, Y.; Dalton, T. P. Role of the aromatic hydrocarbon receptor and [Ah] gene battery in the oxidative stress response, cell cycle control, and apoptosis. Biochem. Pharmacol. 2000, 59 (1), 65−85 DOI: 10.1016/ S0006-2952(99)00310-X. (53) Puga, A.; Xia, Y.; Elferink, C. Role of the aryl hydrocarbon receptor in cell cycle regulation. Chem. Biol. Interact. 2002, 141 (1−2), 117−130 DOI: 10.1016/S0009-2797(02)00069-8. (54) Schrenk, D. Impact of dioxin-type induction of drugmetabolizing enzymes on the metabolism of endo- and xenobiotics. Biochem. Pharmacol. 1998, 55 (8), 1155−1162 DOI: 10.1016/S00062952(97)00591-1. (55) Chiba, T.; Chihara, J.; Furue, M. Role of the arylhydrocarbon receptor (AhR) in the Pathology of Asthma and COPD. J. Allergy 2012, 2012 (2012), 372384 DOI: 10.1155/2012/372384. (56) Esser, C.; Rannug, A.; Stockinger, B. The aryl hydrocarbon receptor in immunity. Trends Immunol. 2009, 30 (9), 447−454 DOI: 10.1016/j.it.2009.06.005. (57) Stevens, E. A.; Mezrich, J. D.; Bradfield, C. A. The aryl hydrocarbon receptor: A perspective on potential roles in the immune system. Immunology 2009, 127 (3), 299−311 DOI: 10.1111/j.13652567.2009.03054.x. (58) Benson, J. M.; Shepherd, D. M. Dietary ligands of the aryl hydrocarbon receptor induce anti-inflammatory and immunoregulatory effects on murine dendritic cells. Toxicol. Sci. 2011, 124 (2), 327− 338 DOI: 10.1093/toxsci/kfr249. (59) Duarte, J. H.; Di Meglio, P.; Hirota, K.; Ahlfors, H.; Stockinger, B. Differential influences of the aryl hydrocarbon receptor on Th17 mediated responses in vitro and in vivo. PloS one 2013, 8 (11), e79819 DOI: 10.1371/journal.pone.0079819. (60) Platzer, B.; Richter, S.; Kneidinger, D.; Waltenberger, D.; Woisetschläger, M.; Strobl, H. Aryl hydrocarbon receptor activation inhibits in vitro differentiation of human monocytes and Langerhans 586



Article

dendritic cells. J. Immunol. 2009, 183 (1), 66−74 DOI: 10.4049/ jimmunol.0802997. (61) Punj, S.; Kopparapu, P.; Jang, H. S.; Phillips, J. L.; Pennington, J.; Rohlman, D.; O’donnell, E.; Iversen, P. L.; Kolluri, S. K.; Kerkvliet, N. I. Benzimidazoisoquinolines: A new class of rapidly metabolized aryl hydrocarbon receptor (AhR) ligands that induce AhR-dependent Tregs and prevent murine graft-versus-host disease. PloS one 2014, 9 (2), e88726 DOI: 10.1371/journal.pone.0088726. (62) Wheeler, J. L.; Martin, K. C.; Resseguie, E.; Lawrence, B. P. Differential consequences of two distinct AhR ligands on innate and adaptive immune responses to influenza A virus. Toxicol. Sci. 2014, 137 (2), 324−334 DOI: 10.1093/toxsci/kft255. (63) Nguyen, N. T.; Hanieh, H.; Nakahama, T.; Kishimoto, T. The roles of aryl hydrocarbon receptor in immune responses. Int. Immunol. 2013, 25 (6), 335−343 DOI: 10.1093/intimm/dxt011. (64) Quintana, F. J.; Basso, A. S.; Iglesias, A. H.; Korn, T.; Farez, M. F.; Bettelli, E.; Caccamo, M.; Oukka, M.; Weiner, H. L. Control of T(reg) and T(H)17 cell differentiation by the aryl hydrocarbon receptor. Nature 2008, 453, 65−71 DOI: 10.1038/nature06880.

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