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Lu Y, Ma W, Tang H, Wu X, Yang X, Sun F. 4-methylimidazole exposure impairs sperm mobility by reducing the expression of blood-testis barrier junction protein in mouse testes. Reprod Biol 2024; 24:100928. [PMID: 39083984 DOI: 10.1016/j.repbio.2024.100928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/30/2024] [Accepted: 07/20/2024] [Indexed: 08/02/2024]
Abstract
4-methylimidazole (4-MI), a derivative of imidazole, is a widely used component in caramel-colored food products such as soy sauce, beer and other soft drinks. The present study is aimed to investigate the effects of 4-MI on the male reproduction. The results revealed that 8 weeks of 4-MI exposure did not significantly alter the body weight and testicular weight of male mice. However, testicular morphology and computer-assisted sperm analysis showed that exposed to 4-MI caused irregular arrangement of spermatogenic cells in the testes and weakened sperm motility. Consistently, we observed the decreased fertilization ability in vivo of 4-MI-treated male mice. We further demonstrated that 4-MI disrupted the blood-testis barrier (BTB) integrity by decreasing the protein expression of BTB-related junction with permeability assay and western blot. In addition, the apoptosis of Sertoli cells (TM4) occurred in 4-MI treated mice, which might be caused by the generation of oxidative stress. Collectively, our findings document that 4-MI exposure damages the sperm mobility via disruption of BTB integrity.
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Affiliation(s)
- Yajuan Lu
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China
| | - Wei Ma
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China
| | - Hanyu Tang
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China
| | - Xue Wu
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China
| | - Xiwen Yang
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China; School of Basic Medical Science, Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Ningxia Medical University, Yinchuan 750004, China
| | - Fei Sun
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China.
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Kobets T, Smith BPC, Williams GM. Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk. Foods 2022; 11:foods11182828. [PMID: 36140952 PMCID: PMC9497933 DOI: 10.3390/foods11182828] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
- Correspondence: ; Tel.: +1-914-594-3105; Fax: +1-914-594-4163
| | - Benjamin P. C. Smith
- Future Ready Food Safety Hub, Nanyang Technological University, Singapore 639798, Singapore
| | - Gary M. Williams
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
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Lu Y, Tang H, Xu J, Sun F. Toxic effects of 4-methylimidazole on the maturation and fertilization of mouse oocytes. Food Chem Toxicol 2022; 164:113051. [PMID: 35460824 DOI: 10.1016/j.fct.2022.113051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/24/2022] [Accepted: 04/15/2022] [Indexed: 11/26/2022]
Abstract
Individuals of all ages, including children and teenagers, consume 4-methylimidazole (4-MI) in their food. 4-MI is a caramel-colored waste product that has previously been linked to human carcinogenesis and has shown possible signs of reproductive toxicity. This study aimed to determine whether 4-MI is harmful to oocytes during meiosis and fertilization. Female mice were intragastrically administered 0, 50, or 100 mg/kg body weight of 4-MI daily for 10 days. We found that 4-MI affects the quality of oocytes by affecting their meiotic ability and fertility potential. Specifically, 4-MI rendered the meiotic spindles and chromosomes less stable, which halted oocyte maturation and resulted in aneuploidy. 4-MI also slowed the decrease in the levels of cortical granules and their component ovastacin; consequently, sperms could not be bound and fertilization could not occur. We also found that mitochondrial dysfunction was associated with oocytes deterioration. This led to reactive oxygen species accumulation and cell death. Altogether, our findings reveal that the poor condition of oocytes subjected to 4-MI is primarily attributable to mitochondrial malfunction and redox alterations.
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Affiliation(s)
- Yajuan Lu
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, 226019, Jiangsu, China
| | - Hanyu Tang
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, 226019, Jiangsu, China
| | - Junjie Xu
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, 226019, Jiangsu, China
| | - Fei Sun
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, 226019, Jiangsu, China.
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Borghoff SJ, Fitch SE, Black MB, McMullen PD, Andersen ME, Chappell GA. A systematic approach to evaluate plausible modes of actions for mouse lung tumors in mice exposed to 4-methylimidozole. Regul Toxicol Pharmacol 2021; 124:104977. [PMID: 34174380 DOI: 10.1016/j.yrtph.2021.104977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/07/2021] [Accepted: 06/21/2021] [Indexed: 12/27/2022]
Abstract
The National Toxicology Program (NTP) reported that chronic dietary exposure to 4-methylimidazole (4-MeI) increased the incidence of lung adenomas/carcinomas beyond the normally high spontaneous rate in B6C3F1 mice. To examine plausible modes of action (MoAs) for mouse lung tumors (MLTs) upon exposure to high levels of 4-MeI, and their relevance in assessing human risk, a systematic approach was used to identify and evaluate mechanistic data (in vitro and in vivo) in the primary and secondary literature, along with high-throughput screening assay data. Study quality, relevance, and activity of mechanistic data identified across the evidence-base were organized according to key characteristics of carcinogens (KCCs) to identify potential key events in known or novel MLT MoAs. Integration of these evidence streams provided confirmation that 4-MeI lacks genotoxic and cytotoxic activity with some evidence to support a lack of mitogenic activity. Further evaluation of contextual and chemical-specific characteristics of 4-MeI was consequently undertaken. Due to lack of genotoxicity, along with transcriptomic and histopathological lung changes up to 28 and 90 days of exposure, the collective evidence suggests MLTs observed following exposure to high levels of 4-MeI develop at a late stage in the mouse chronic bioassay, albeit the exact MoA remains unclear.
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Buczkowska M, Paciorek K, Kapcińska A, Górski M. Caramel colors in terms of scientific research, with particular
consideration of their toxicity. POSTEP HIG MED DOSW 2021. [DOI: 10.5604/01.3001.0014.8497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Caramel colors, the most common food additives in the world, are divided into four classes (IIV),
marked with the symbols E150 a-d, respectively. Individual classes of caramel colors differ
from each other in physico-chemical properties and the method of preparation, which affects
the formation of various compounds that are important for the assessment of food safety A number of studies on all caramel classes of have been performed, including toxicokinetic,
genotoxic, carcinogenic and reproductive and developmental toxicity studies, which have
not shown harmful effects of these additives at doses not exceeding ADI. However, there is
an increasing number of scientific reports of the possible toxic effects present in caramels of
low-molecular compounds. Currently, three compounds are considered to be toxicologically
important and resulting from the possible concentration in the final product: 5-HMF (present
in all classes), 4(5)-MeI (present in caramel classes III and IV) or THI (present in caramel
class III). 4(5)-MeI has a neurotoxic effect and was considered in 2011 as a possible human
carcinogen (class 2B, according to IARC). In the case of THI, studies have confirmed its lymphopenic
activity, probably secondary to its immunosuppressive effect. Consequently, in the
1980s, JECFA set acceptable levels 4(5)-MeI and THI, for the caramel classes in which these
compounds may be present. The toxicity of 5-HMF has not been confirmed unequivocally,
but studies have shown that this compound is not neutral to living organisms.
Currently, most international organizations and scientific institutes recognize these additives
as safe for consumers, but at the same time scientists emphasize the need for further
research.
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Affiliation(s)
- Marta Buczkowska
- Zakład Toksykologii i Ochrony Zdrowia w Środowisku Pracy, Katedra Toksykologii i Uzależnień, Wydział Nauk o Zdrowiu w Bytomiu, Śląski Uniwersytet Medyczny w Katowicach
| | - Kamila Paciorek
- Drugie Koło Naukowe przy Zakładzie Toksykologii i Ochrony Zdrowia w Środowisku Pracy, Katedra Toksykologii i Uzależnień
| | - Anna Kapcińska
- Drugie Koło Naukowe przy Zakładzie Toksykologii i Ochrony Zdrowia w Środowisku Pracy, Katedra Toksykologii i Uzależnień
| | - Michał Górski
- Szkoła Doktorska Śląskiego Uniwersytetu Medycznego w Katowicach, Wydział Nauk o Zdrowiu w Bytomiu Śląski Uniwersytet Medyczny
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Capriello T, Visone IM, Motta CM, Ferrandino I. Adverse effects of E150d on zebrafish development. Food Chem Toxicol 2021; 147:111877. [DOI: 10.1016/j.fct.2020.111877] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/02/2020] [Accepted: 11/19/2020] [Indexed: 12/22/2022]
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Kelty JS, Keum C, Brown VJ, Edwards PC, Carratt SA, Van Winkle LS. Comparison of acute respiratory epithelial toxicity for 4-Methylimidazole and naphthalene administered by oral gavage in B6C3F1 mice. Regul Toxicol Pharmacol 2020; 116:104761. [PMID: 32768664 DOI: 10.1016/j.yrtph.2020.104761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/01/2020] [Accepted: 08/04/2020] [Indexed: 11/28/2022]
Abstract
4-Methylimidazole (4MEI) is a contaminant in food and consumer products. Pulmonary toxicity and carcinogenicity following chronic dietary exposures to 4MEI is a regulatory concern based on previous rodent studies. This study examined acute pulmonary toxicity in B6C3F1 mice from 6 h to 5 days after oral gavage with a single dose of 150 mg/kg 4MEI, a double dose delivered 6 h apart, or vehicle controls. Oral gavage of 150 mg/kg naphthalene, a prototypical Club cell toxicant, was used as a positive control. Intrapulmonary conducting airway cytotoxicity was assessed in fixed-pressure inflated lungs using qualitative histopathology scoring, quantitative morphometric measurement of vacuolated and exfoliating epithelial cells, and immunohistochemistry. 4MEI treatment did not change markers of cytotoxicity including the mass of vacuolated epithelium, the thickness of the epithelium, or the distributions of epithelial proteins: secretoglobin 1A1, proliferating cell nuclear antigen, calcitonin gene-related peptide, and myeloperoxidase. 4MEI and vehicle controls caused slight cytotoxicity with rare vacuolization of the epithelium relative to the severe bronchiolar epithelial cell toxicity found in the naphthalene exposed mice at terminal bronchioles, intrapulmonary airways, or airway bifurcations. In summary, 4MEI caused minimal airway epithelial toxicity without characteristic Club Cell toxicity when compared to naphthalene, a canonical Club Cell toxicant.
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Affiliation(s)
- Jacklyn S Kelty
- Center for Health and Environment, University of California, Davis, Bldg 3792, Rm 129, 1250 Old Davis Road, Davis, 95616, CA, USA.
| | - Chayoung Keum
- Center for Health and Environment, University of California, Davis, Bldg 3792, Rm 129, 1250 Old Davis Road, Davis, 95616, CA, USA.
| | - Veneese J Brown
- Center for Health and Environment, University of California, Davis, Bldg 3792, Rm 129, 1250 Old Davis Road, Davis, 95616, CA, USA.
| | - Patricia C Edwards
- Center for Health and Environment, University of California, Davis, Bldg 3792, Rm 129, 1250 Old Davis Road, Davis, 95616, CA, USA.
| | - Sarah A Carratt
- Center for Health and Environment, University of California, Davis, Bldg 3792, Rm 129, 1250 Old Davis Road, Davis, 95616, CA, USA.
| | - Laura S Van Winkle
- Center for Health and Environment, University of California, Davis, Bldg 3792, Rm 129, 1250 Old Davis Road, Davis, 95616, CA, USA; Department of Anatomy, Physiology and Cell Biology School of Veterinary Medicine, University of California, Davis, One Shields Ave, Davis, 95616, CA, USA.
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A weight of evidence assessment of the genotoxic potential of 4-methylimidazole as a possible mode of action for the formation of lung tumors in exposed mice. Food Chem Toxicol 2020; 145:111652. [PMID: 32745573 DOI: 10.1016/j.fct.2020.111652] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/08/2020] [Accepted: 07/24/2020] [Indexed: 12/16/2022]
Abstract
4-Methylimidazole (4-MeI) is a byproduct formed during the cooking of foods containing carbohydrates and amino acids, including the production of flavors and coloring substances, e.g., class III and IV caramel colors, used in many food products with extensive human exposure. Two-year rodent bioassays via oral exposure conducted by the National Toxicology Program reported evidence of carcinogenicity only in B6C3F1 mice (increased alveolar/bronchial neoplasms). In 2011, the International Agency for Research on Cancer classified 4-MeI as Group 2B, "possibly carcinogenic to humans". An expert panel was commissioned to assess the genotoxic potential of 4-MeI and the plausibility of a genotoxic mode of action in the formation of lung tumors in mice when exposed to high doses of 4-MeI. The panel defined and used a weight-of-evidence (WOE) approach that included thorough evaluation of studies assessing the genotoxic potential of 4-MeI. The panelists categorized each study, consisting of study weight, degree of technical performance, study reliability, and contribution to the overall WOE. Based on the reviewed studies' weighted contribution, the panel unanimously concluded that the WOE supports no clear evidence of in vivo genotoxicity of 4-MeI and no association for a genotoxic mode of action in the formation of mouse lung tumors.
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Howard AS, Choksi N. Evaluation of two in silico programs for predicting mutagenicity and carcinogenicity potential for 4-methylimidazole (4-MeI) and known metabolites. Toxicol Mech Methods 2020; 30:246-256. [PMID: 31903850 DOI: 10.1080/15376516.2019.1709237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
4-Methylimidazole (4-MeI) is a nitrogen-containing heterocyclic compound that is used in the manufacture of chemicals, dyes and pharmaceuticals and may be found in a variety of foods following formation during heating. The purpose of this study was to use two different in silico programs, CASE Ultra and Toxtree, to investigate potential structure-activity relationships in 4-MeI and its metabolites for mutagenicity and carcinogenicity, and combine that information with the available literature to draw conclusions regarding the strength of the predictions observed. Neither CASE Ultra nor Toxtree identified any structural alerts that were associated with mutagenic activity. Data for 4-MeI from a single study were used in the development of the CASE Ultra mouse and rat carcinogenicity models, but no additional similar structures were identified in the carcinogenicity model training set. One metabolite, 5-methylhydantoin, was predicted to be positive in the CASE Ultra carcinogenicity male and female mouse models; positive predictivity percentages of 60.9% and 73.7%, respectively. However, low structural similarity between 5-methylhydantoin and the compounds identified in the training set (<25%) decreases confidence in the positive prediction. Three metabolites were predicted to be positive in the CASE Ultra mouse micronucleus model, but again suffered from low structural similarity. Both limited structural similarity and inconsistent responses among the other clastogenicity models suggest that additional structurally similar compounds are needed to assess the predictive capacity of these alerts for biological activity of these compounds.
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Affiliation(s)
- Angela S Howard
- Integrated Laboratory Systems, Inc, Research Triangle Park, NC, USA
| | - Neepa Choksi
- Integrated Laboratory Systems, Inc, Research Triangle Park, NC, USA
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