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Peña LCS, Hernández AB, Del Razo LM. Decreased Arsenic Disposition and Alteration of its Metabolic Profile in mice Coexposed to Fluoride. Biol Trace Elem Res 2024; 202:1594-1602. [PMID: 37450204 PMCID: PMC10859321 DOI: 10.1007/s12011-023-03764-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 07/03/2023] [Indexed: 07/18/2023]
Abstract
Inorganic arsenic (iAs) and fluoride (iF) are ubiquitous elements whose coexistence is frequent in several regions of the world due to the natural contamination of water sources destined for human consumption. It has been reported that coexposure to these two elements in water can cause toxic effects on health, which are controversial since antagonistic and synergistic effects have been reported. However, there is little information on the possible toxicological interaction between concurrent exposure to iAs and iF on the iAs metabolism profile.The goal of this study was to determine the effect of iF exposure on iAs methylation patterns in the urine and the tissues of female mice of the C57BL/6 strain, which were divided into four groups and exposed daily for 10 days through drinking water as follows: purified water (control); arsenite 1 mg/L, fluoride 50 mg/L and arsenite & fluoride 1:50 mg/L.To characterize the iAs methylation pattern in concomitant iF exposure, iAs and its methylated metabolites (MAs and DMAs) were quantified in the tissues and the urine of mice was exposed to iAs alone or in combination. Our results showed a statistically significant decrease in the arsenic species concentrations and altered relative proportions of arsenic species in tissues and urine in the As-iF coexposure group compared to the iAs-exposed group. These findings show that iF exposure decreases arsenic disposition and alters methylation capacity.Nevertheless, additional studies are required to elucidate the mechanisms involved in the iAs-iF interaction through iF exposure affecting iAs disposition and metabolism.
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Affiliation(s)
- Luz C Sanchez Peña
- Departmento de Toxicologia, Centro de Investigación y de Estudios Avanzados, Av. IPN 2508, San Pedro Zacatenco, Mexico City, 07360, Mexico
| | - Angel Barrera Hernández
- Departmento de Toxicologia, Centro de Investigación y de Estudios Avanzados, Av. IPN 2508, San Pedro Zacatenco, Mexico City, 07360, Mexico
| | - Luz M Del Razo
- Departmento de Toxicologia, Centro de Investigación y de Estudios Avanzados, Av. IPN 2508, San Pedro Zacatenco, Mexico City, 07360, Mexico.
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2
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Alzahrani AY, Alamoudi NMH, El Meligy OAES. Contemporary Understanding of the Etiology and Management of Molar Incisor Hypomineralization: A Literature Review. Dent J (Basel) 2023; 11:157. [PMID: 37504223 PMCID: PMC10378579 DOI: 10.3390/dj11070157] [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: 03/22/2023] [Revised: 06/07/2023] [Accepted: 06/21/2023] [Indexed: 07/29/2023] Open
Abstract
Molar incisor hypomineralization (MIH) is a significant health problem that can affect the child's quality of life by negatively affecting their esthetics and function. This review aimed to summarize the etiology and pathogenesis of MIH. It also aimed to summarize the recent studies on MIH in children and adolescents, focusing on diagnosis, prevention, and clinical management. An electronic search on the PubMed, Cochrane Database of Systematic Reviews, MEDLINE, MedlinePlus, WHO reports, and Google Scholar databases was performed. The volume of research on the etiology, presentation, and clinical management of MIH is still expanding. The creation and validation of indices for the diagnosis and management of MIH, as well as any potential genetic aspects appear to be the main areas of current research. Notably, MIH was linked to childhood illnesses, the use of antibiotics, and early childhood fever. Although many studies discuss the different options for managing MIH lesions, evidence-based studies that address the long-term outcomes of MIH are still lacking. Indeed, future clinical studies should be directed to evaluate the impact of each systemic etiological factor and its different types of management on normal amelogenesis. Regarding the diagnosis, future research should focus on the pre-eruption diagnosis and early approaches to prevent the post-eruption breakdown and caries. Regarding the treatment of MIH, future investigations should emphasize further improvements in adhesion and the use of new materials and techniques, such as digital dentistry.
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Affiliation(s)
- Ahmed Yahya Alzahrani
- Pediatric Dentistry Department, Faculty of Dentistry, King Abdulaziz University, P.O. Box 80209, Jeddah 21589, Saudi Arabia
- Pediatric Dentistry, Taif Dental Centre, Ministry of Health, Taif 26511, Saudi Arabia
| | | | - Omar Abd El Sadek El Meligy
- Pediatric Dentistry Department, Faculty of Dentistry, King Abdulaziz University, P.O. Box 80209, Jeddah 21589, Saudi Arabia
- Pediatric Dentistry & Dental Public Health Department, Faculty of Dentistry, Alexandria University, Alexandria 21521, Egypt
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3
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Li L, Xin J, Wang H, Wang Y, Peng W, Sun N, Huang H, Zhou Y, Liu X, Lin Y, Fang J, Jing B, Pan K, Zeng Y, Zeng D, Qin X, Bai Y, Ni X. Fluoride disrupts intestinal epithelial tight junction integrity through intracellular calcium-mediated RhoA/ROCK signaling and myosin light chain kinase. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 257:114940. [PMID: 37099960 DOI: 10.1016/j.ecoenv.2023.114940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/12/2023] [Accepted: 04/18/2023] [Indexed: 05/08/2023]
Abstract
Fluoride is a common contaminant of groundwater and agricultural commodity, which poses challenges to animal and human health. A wealth of research has demonstrated its detrimental effects on intestinal mucosal integrity; however, the underlying mechanisms remain obscure. This study aimed to investigate the role of the cytoskeleton in fluoride-induced barrier dysfunction. After sodium fluoride (NaF) treatment of the cultured Caco-2 cells, both cytotoxicity and cytomorphological changes (internal vacuoles or massive ablation) were observed. NaF lowered transepithelial electrical resistance (TEER) and enhanced paracellular permeation of fluorescein isothiocyanate dextran 4 (FD-4), indicating Caco-2 monolayers hyperpermeability. In the meantime, NaF treatment altered both the expression and distribution of the tight junction protein ZO-1. Fluoride exposure increased myosin light chain II (MLC2) phosphorylation and triggered actin filament (F-actin) remodeling. While inhibition of myosin II by Blebbistatin blocked NaF-induced barrier failure and ZO-1 discontinuity, the corresponding agonist Ionomycin had effects comparable to those of fluoride, suggesting that MLC2 serves as an effector. Given the mechanisms upstream of p-MLC2 regulation, further studies demonstrated that NaF activated RhoA/ROCK signaling pathway and myosin light chain kinase (MLCK), strikingly increasing the expression of both. Pharmacological inhibitors (Rhosin, Y-27632 and ML-7) reversed NaF-induced barrier breakdown and stress fiber formation. The role of intracellular calcium ions ([Ca2+]i) in NaF effects on Rho/ROCK pathway and MLCK was investigated. We found that NaF elevated [Ca2+]i, whereas chelator BAPTA-AM attenuated increased RhoA and MLCK expression as well as ZO-1 rupture, thus, restoring barrier function. Collectively, abovementioned results suggest that NaF induces barrier impairment via Ca2+-dependent RhoA/ROCK pathway and MLCK, which in turn triggers MLC2 phosphorylation and rearrangement of ZO-1 and F-actin. These results provide potential therapeutic targets for fluoride-induced intestinal injury.
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Affiliation(s)
- Lianxin Li
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Jinge Xin
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Hesong Wang
- Baiyun Branch, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yadong Wang
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology of Guangdong Province, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Weiqi Peng
- Baiyun Branch, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Ning Sun
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Haonan Huang
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yanxi Zhou
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Xingmei Liu
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yu Lin
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology of Guangdong Province, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jing Fang
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Bo Jing
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Kangcheng Pan
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yan Zeng
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Dong Zeng
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Xiang Qin
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China.
| | - Yang Bai
- Baiyun Branch, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology of Guangdong Province, Nanfang Hospital, Southern Medical University, Guangzhou, China.
| | - Xueqin Ni
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China.
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Enamel Phenotypes: Genetic and Environmental Determinants. Genes (Basel) 2023; 14:genes14030545. [PMID: 36980818 PMCID: PMC10048525 DOI: 10.3390/genes14030545] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 02/24/2023] Open
Abstract
Dental enamel is a specialized tissue that has adapted over millions of years of evolution to enhance the survival of a variety of species. In humans, enamel evolved to form the exterior protective layer for the crown of the exposed tooth crown. Its unique composition, structure, physical properties and attachment to the underlying dentin tissue allow it to be a resilient, although not self-repairing, tissue. The process of enamel formation, known as amelogenesis, involves epithelial-derived cells called ameloblasts that secrete a unique extracellular matrix that influences the structure of the mineralizing enamel crystallites. There are over 115 known genetic conditions affecting amelogenesis that are associated with enamel phenotypes characterized by either a reduction of enamel amount and or mineralization. Amelogenesis involves many processes that are sensitive to perturbation and can be altered by numerous environmental stressors. Genetics, epigenetics, and environment factors can influence enamel formation and play a role in resistance/risk for developmental defects and the complex disease, dental caries. Understanding why and how enamel is affected and the enamel phenotypes seen clinically support diagnostics, prognosis prediction, and the selection of treatment approaches that are appropriate for the specific tissue defects (e.g., deficient amount, decreased mineral, reduced insulation and hypersensitivity). The current level of knowledge regarding the heritable enamel defects is sufficient to develop a new classification system and consensus nosology that effectively communicate the mode of inheritance, molecular defect/pathway, and the functional aberration and resulting enamel phenotype.
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ROS-Mediated Enamel Formation Disturbance Characterized by Alternative Cervical Loop Cell Proliferation and Downregulation of RhoA/ROCK in Ameloblasts. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:5769679. [DOI: 10.1155/2022/5769679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/18/2022] [Indexed: 11/17/2022]
Abstract
Reactive oxygen stress (ROS) is generally accepted as a signal transducer for coordinating the growth and differentiation of tissues and organs in the oral and maxillofacial region. Although ROS has been confirmed to affect the development of enamel, it is not yet known that the specific mechanism of ROS accumulation induced enamel defects. Given the lack of knowledge of the role of ROS in enamel, the aim of the study is to determine how oxidative stress affects cervical cells and ameloblast cells. Using SOD1 knockout mice, we identified a relationship between ROS fluctuations and abnormal enamel structure with HE staining, micro-CT, and scanning electron microscope. Increased ROS induced by H2O2, certified by the DCFH probe, has resulted in a dual effect on the proliferation and differentiation of cervical cells, indicating a higher tendency to proliferate at low ROS concentrations. Ameloblasts transfected with SOD1 siRNA showed a significant reduction of RhoA and ROCK. This study investigates for the first time that SOD1-mediated ROS accumulation disrupted normal enamel structure through alternative cervical loop cell proliferation and downregulation of RhoA and ROCK in ameloblasts, demonstrating the convoluted role of ROS in monitoring the progress of enamel defects.
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Földes A, Sang-Ngoen T, Kádár K, Rácz R, Zsembery Á, DenBesten P, Steward MC, Varga G. Three-Dimensional Culture of Ameloblast-Originated HAT-7 Cells for Functional Modeling of Defective Tooth Enamel Formation. Front Pharmacol 2021; 12:682654. [PMID: 34149428 PMCID: PMC8206558 DOI: 10.3389/fphar.2021.682654] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/19/2021] [Indexed: 01/04/2023] Open
Abstract
Background: Amelogenesis, the formation of dental enamel, is well understood at the histomorphological level but the underlying molecular mechanisms are poorly characterized. Ameloblasts secrete enamel matrix proteins and Ca2+, and also regulate extracellular pH as the formation of hydroxyapatite crystals generates large quantities of protons. Genetic or environmental impairment of transport and regulatory processes (e.g. dental fluorosis) leads to the development of enamel defects such as hypomineralization. Aims: Our aims were to optimize the culture conditions for the three-dimensional growth of ameloblast-derived HAT-7 cells and to test the effects of fluoride exposure on HAT-7 spheroid formation. Methods: To generate 3D HAT-7 structures, cells were dispersed and plated within a Matrigel extracellular matrix scaffold and incubated in three different culture media. Spheroid formation was then monitored over a two-week period. Ion transporter and tight-junction protein expression was investigated by RT-qPCR. Intracellular Ca2+ and pH changes were measured by microfluorometry using the fluorescent dyes fura-2 and BCECF. Results: A combination of Hepato-STIM epithelial cell differentiation medium and Matrigel induced the expansion and formation of 3D HAT-7 spheroids. The cells retained their epithelial cell morphology and continued to express both ameloblast-specific and ion transport-specific marker genes. Furthermore, like two-dimensional HAT-7 monolayers, the HAT-7 spheroids were able to regulate their intracellular pH and to show intracellular calcium responses to extracellular stimulation. Finally, we demonstrated that HAT-7 spheroids may serve as a disease model for studying the effects of fluoride exposure during amelogenesis. Conclusion: In conclusion, HAT-7 cells cultivated within a Matrigel extracellular matrix form three-dimensional, multi-cellular, spheroidal structures that retain their functional capacity for pH regulation and intracellular Ca2+ signaling. This new 3D model will allow us to gain a better understanding of the molecular mechanisms involved in amelogenesis, not only in health but also in disorders of enamel formation, such as those resulting from fluoride exposure.
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Affiliation(s)
- Anna Földes
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | | | - Kristóf Kádár
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Róbert Rácz
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Ákos Zsembery
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Pamela DenBesten
- Department of Orofacial Sciences, University of California San Francisco, San Francisco, CA, United States
| | - Martin C Steward
- Department of Oral Biology, Semmelweis University, Budapest, Hungary.,School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Gábor Varga
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
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7
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Dionizio A, Uyghurturk DA, Melo CGS, Sabino-Arias IT, Araujo TT, Ventura TMS, Perles JVCM, Zanoni JN, Den Besten P, Buzalaf MAR. Intestinal changes associated with fluoride exposure in rats: Integrative morphological, proteomic and microbiome analyses. CHEMOSPHERE 2021; 273:129607. [PMID: 33508686 PMCID: PMC8076095 DOI: 10.1016/j.chemosphere.2021.129607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/14/2020] [Accepted: 01/06/2021] [Indexed: 05/10/2023]
Abstract
Gastrointestinal signs and symptoms are the first signs of toxicity due to exposure to fluoride (F). This suggests the possibility that lower levels of subchronic F exposure may affect the gut. The aim of this study was to evaluate changes in the morphology, proteome and microbiome of the ileum of rats, after subchronic exposure to F. Male rats ingested water with 0, 10, or 50 mgF/L for thirty days. Treatment with F, regardless of the dose, significantly decreased the density of HuC/D-IR neurons, whereas CGRP-IR and SP-IR varicosities were significantly increased compared to the control group. Increased VIP-IR varicosities were significantly increased only in the group treated with 50 mgF/L. A significant increase in thickness of the tunica muscularis, as well as in the total thickness of the ileum wall was observed at both F doses when compared to controls. In proteomics analysis, myosin isoforms were increased, and Gastrotopin was decreased in F-exposed mice. In the microbiome metagenomics analysis, Class Clostridia was significantly reduced upon exposure to 10 mgF/L. At the higher F dose of 50 mg/L, genus Ureaplasma was significantly reduced in comparison with controls. Morphological and proteomics alterations induced by F were marked by changes associated with inflammation, and alterations in the gut microbiome. Further studies are needed to determine whether F exposure increases inflammation with secondary effects of the gut microbiome, and/or whether primary effects of F on the gut microbiome enhance changes associated with inflammation.
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Affiliation(s)
- Aline Dionizio
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | - Dawud Abduweli Uyghurturk
- Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco, San Francisco, USA
| | | | | | - Tamara Teodoro Araujo
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | | | | | | | - Pamela Den Besten
- Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco, San Francisco, USA.
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TRPM7-Mediated Calcium Transport in HAT-7 Ameloblasts. Int J Mol Sci 2021; 22:ijms22083992. [PMID: 33924361 PMCID: PMC8069123 DOI: 10.3390/ijms22083992] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/05/2021] [Accepted: 04/08/2021] [Indexed: 02/06/2023] Open
Abstract
TRPM7 plays an important role in cellular Ca2+, Zn2+ and Mg2+ homeostasis. TRPM7 channels are abundantly expressed in ameloblasts and, in the absence of TRPM7, dental enamel is hypomineralized. The potential role of TRPM7 channels in Ca2+ transport during amelogenesis was investigated in the HAT-7 rat ameloblast cell line. The cells showed strong TRPM7 mRNA and protein expression. Characteristic TRPM7 transmembrane currents were observed, which increased in the absence of intracellular Mg2+ ([Mg2+]i), were reduced by elevated [Mg2+]i, and were inhibited by the TRPM7 inhibitors NS8593 and FTY720. Mibefradil evoked similar currents, which were suppressed by elevated [Mg2+]i, reducing extracellular pH stimulated transmembrane currents, which were inhibited by FTY720. Naltriben and mibefradil both evoked Ca2+ influx, which was further enhanced by the acidic intracellular conditions. The SOCE inhibitor BTP2 blocked Ca2+ entry induced by naltriben but not by mibefradil. Thus, in HAT-7 cells, TRPM7 may serves both as a potential modulator of Orai-dependent Ca2+ uptake and as an independent Ca2+ entry pathway sensitive to pH. Therefore, TRPM7 may contribute directly to transepithelial Ca2+ transport in amelogenesis.
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Racz R, Nagy A, Rakonczay Z, Dunavari EK, Gerber G, Varga G. Defense Mechanisms Against Acid Exposure by Dental Enamel Formation, Saliva and Pancreatic Juice Production. Curr Pharm Des 2019; 24:2012-2022. [PMID: 29769002 PMCID: PMC6225347 DOI: 10.2174/1381612824666180515125654] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 04/30/2018] [Accepted: 05/08/2018] [Indexed: 12/16/2022]
Abstract
The pancreas, the salivary glands and the dental enamel producing ameloblasts have marked developmental, structural and functional similarities. One of the most striking similarities is their bicarbonate-rich secretory product, serving acid neutralization. An important difference between them is that while pancreatic juice and saliva are delivered into a lumen where they can be collected and analyzed, ameloblasts produce locally precipitating hydroxyapatite which cannot be easily studied. Interestingly, the ion and protein secretion by the pancreas, the salivary glands, and maturation ameloblasts are all two-step processes, of course with significant differences too. As they all have to defend against acid exposure by producing extremely large quantities of bicarbonate, the failure of this function leads to deteriorating consequences. The aim of the present review is to describe and characterize the defense mechanisms of the pancreas, the salivary glands and enamel-producing ameloblasts against acid exposure and to compare their functional capabilities to do this by producing bicarbonate.
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Affiliation(s)
- Robert Racz
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Akos Nagy
- Department of Dentistry, Oral and Maxillofacial Surgery, University of Pecs, Pecs, Hungary
| | - Zoltan Rakonczay
- Department of Pathophysiology, University of Szeged, Szeged, Hungary
| | - Erika Katalin Dunavari
- Department of Dentistry, Oral and Maxillofacial Surgery, University of Pecs, Pecs, Hungary
| | - Gabor Gerber
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Gabor Varga
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
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Pandya M, Diekwisch TGH. Enamel biomimetics-fiction or future of dentistry. Int J Oral Sci 2019. [PMID: 30610185 DOI: 10.1038/s41368-018-0038-6,1-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Tooth enamel is a complex mineralized tissue consisting of long and parallel apatite crystals configured into decussating enamel rods. In recent years, multiple approaches have been introduced to generate or regenerate this highly attractive biomaterial characterized by great mechanical strength paired with relative resilience and tissue compatibility. In the present review, we discuss five pathways toward enamel tissue engineering, (i) enamel synthesis using physico-chemical means, (ii) protein matrix-guided enamel crystal growth, (iii) enamel surface remineralization, (iv) cell-based enamel engineering, and (v) biological enamel regeneration based on de novo induction of tooth morphogenesis. So far, physical synthesis approaches using extreme environmental conditions such as pH, heat and pressure have resulted in the formation of enamel-like crystal assemblies. Biochemical methods relying on enamel proteins as templating matrices have aided the growth of elongated calcium phosphate crystals. To illustrate the validity of this biochemical approach we have successfully grown enamel-like apatite crystals organized into decussating enamel rods using an organic enamel protein matrix. Other studies reviewed here have employed amelogenin-derived peptides or self-assembling dendrimers to re-mineralize mineral-depleted white lesions on tooth surfaces. So far, cell-based enamel tissue engineering has been hampered by the limitations of presently existing ameloblast cell lines. Going forward, these limitations may be overcome by new cell culture technologies. Finally, whole-tooth regeneration through reactivation of the signaling pathways triggered during natural enamel development represents a biological avenue toward faithful enamel regeneration. In the present review we have summarized the state of the art in enamel tissue engineering and provided novel insights into future opportunities to regenerate this arguably most fascinating of all dental tissues.
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Affiliation(s)
- Mirali Pandya
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, Dallas, TX, USA
| | - Thomas G H Diekwisch
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, Dallas, TX, USA.
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11
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Abstract
Tooth enamel is a complex mineralized tissue consisting of long and parallel apatite crystals configured into decussating enamel rods. In recent years, multiple approaches have been introduced to generate or regenerate this highly attractive biomaterial characterized by great mechanical strength paired with relative resilience and tissue compatibility. In the present review, we discuss five pathways toward enamel tissue engineering, (i) enamel synthesis using physico-chemical means, (ii) protein matrix-guided enamel crystal growth, (iii) enamel surface remineralization, (iv) cell-based enamel engineering, and (v) biological enamel regeneration based on de novo induction of tooth morphogenesis. So far, physical synthesis approaches using extreme environmental conditions such as pH, heat and pressure have resulted in the formation of enamel-like crystal assemblies. Biochemical methods relying on enamel proteins as templating matrices have aided the growth of elongated calcium phosphate crystals. To illustrate the validity of this biochemical approach we have successfully grown enamel-like apatite crystals organized into decussating enamel rods using an organic enamel protein matrix. Other studies reviewed here have employed amelogenin-derived peptides or self-assembling dendrimers to re-mineralize mineral-depleted white lesions on tooth surfaces. So far, cell-based enamel tissue engineering has been hampered by the limitations of presently existing ameloblast cell lines. Going forward, these limitations may be overcome by new cell culture technologies. Finally, whole-tooth regeneration through reactivation of the signaling pathways triggered during natural enamel development represents a biological avenue toward faithful enamel regeneration. In the present review we have summarized the state of the art in enamel tissue engineering and provided novel insights into future opportunities to regenerate this arguably most fascinating of all dental tissues. Five pathways for tooth enamel engineering hold great promise for developing new technologies, leading to novel biomaterials and biotechnologies to regenerate enamel tissue. Tooth enamel is a unique tissue-specific biomaterial with exceptional structural and mechanical properties. In recent years, many approaches have been adopted to generate or regenerate this complex tissue; Mirali Pandya and Thomas Diekwisch of Texas A&M College of Dentistry, USA conducted a review of the current state and future directions of enamel tissue engineering. In their review, the authors focused on five pathways for enamel tissue engineering: (1) physical synthesis of enamel; (2) biochemical enamel engineering; (3) in situ enamel engineering; (4) cell-based enamel engineering; and (5) whole tooth regeneration. The authors conclude that those five approaches will help identify the biological mechanisms that lead to the generation of tooth enamel.
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12
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Kim HE, Hong JH. The overview of channels, transporters, and calcium signaling molecules during amelogenesis. Arch Oral Biol 2018; 93:47-55. [PMID: 29803993 DOI: 10.1016/j.archoralbio.2018.05.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/18/2018] [Accepted: 05/19/2018] [Indexed: 01/02/2023]
Abstract
Enamel is a highly calcified tissue. Its formation requires a progressive and dynamic system for the regulation of electrolyte concentration by enamel epithelia. A critical function of enamel epithelial cells, ameloblasts, is the secretion and movement of electrolytes via various channels and transporters to develop the enamel tissue. Enamel formation generates protons, which need to be neutralised. Thus, ameloblasts possess a buffering system to sustain mineral accretion. Normal tooth formation involves stage-dependent net fluctuations in pH during amelogenesis. To date, all of our information about ion transporters in dental enamel tissue is based solely on immunostaining-expression techniques. This review critically evaluates the current understanding and recent discoveries and physiological role of ion channels and transporters, Mg2+ transporters, and Ca2+ regulatory proteins during amelogenesis in enamel formation. The ways in which ameloblasts modulate ions are discussed in the context of current research for developing a novel morphologic-functional model of enamel maturation.
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Affiliation(s)
- Hee-Eun Kim
- Department of Dental Hygiene, College of Health Science, Gachon University, 191 Hambangmoe-ro, Yeonsu-gu, Incheon, 21936, South Korea
| | - Jeong Hee Hong
- Department of Physiology, College of Medicine, Lee Gil Ya Cancer and Diabetes Institute, GAIHST, Gachon University, Incheon, 21999, South Korea.
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13
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Varga G, DenBesten P, Rácz R, Zsembery Á. Importance of bicarbonate transport in pH control during amelogenesis - need for functional studies. Oral Dis 2017; 24:879-890. [PMID: 28834043 DOI: 10.1111/odi.12738] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 08/13/2017] [Indexed: 12/27/2022]
Abstract
Dental enamel, the hardest mammalian tissue, is produced by ameloblasts. Ameloblasts show many similarities to other transporting epithelia although their secretory product, the enamel matrix, is quite different. Ameloblasts direct the formation of hydroxyapatite crystals, which liberate large quantities of protons that then need to be buffered to allow mineralization to proceed. Buffering requires a tight pH regulation and secretion of bicarbonate by ameloblasts. Many investigations have used immunohistochemical and knockout studies to determine the effects of these genes on enamel formation, but up till recently very little functional data were available for mineral ion transport. To address this, we developed a novel 2D in vitro model using HAT-7 ameloblast cells. HAT-7 cells can be polarized and develop functional tight junctions. Furthermore, they are able to accumulate bicarbonate ions from the basolateral to the apical fluid spaces. We propose that in the future, the HAT-7 2D system along with similar cellular models will be useful to functionally model ion transport processes during amelogenesis. Additionally, we also suggest that similar approaches will allow a better understanding of the regulation of the cycling process in maturation-stage ameloblasts, and the pH sensory mechanisms, which are required to develop sound, healthy enamel.
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Affiliation(s)
- G Varga
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - P DenBesten
- Department of Orofacial Sciences, University of California, San Francisco, CA, USA
| | - R Rácz
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Á Zsembery
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
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