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Ghio AJ, Soukup JM, Dailey LA, Roggli VL. Mucus increases cell iron uptake to impact the release of pro-inflammatory mediators after particle exposure. Sci Rep 2023; 13:3925. [PMID: 36894564 PMCID: PMC9998431 DOI: 10.1038/s41598-023-30335-2] [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: 10/06/2022] [Accepted: 02/21/2023] [Indexed: 03/11/2023] Open
Abstract
We tested the hypothesis that (1) mucus production can be included in the cell response to iron deficiency; (2) mucus binds iron and increases cell metal uptake; and subsequently (3) mucus impacts the inflammatory response to particle exposure. Using quantitative PCR, RNA for both MUC5B and MUC5AC in normal human bronchial epithelial (NHBE) cells decreased following exposures to ferric ammonium citrate (FAC). Incubation of mucus-containing material collected from the apical surface of NHBE cells grown at air-liquid interface (NHBE-MUC) and a commercially available mucin from porcine stomach (PORC-MUC) with iron demonstrated an in vitro capacity to bind metal. Inclusion of either NHBE-MUC or PORC-MUC in incubations of both BEAS-2B cells and THP1 cells increased iron uptake. Exposure to sugar acids (N-acetyl neuraminic acid, sodium alginate, sodium guluronate, and sodium hyaluronate) similarly increased cell iron uptake. Finally, increased metal transport associated with mucus was associated with a decreased release of interleukin-6 and -8, an anti-inflammatory effect, following silica exposure. We conclude that mucus production can be involved in the response to a functional iron deficiency following particle exposure and mucus can bind metal, increase cell uptake to subsequently diminish or reverse a functional iron deficiency and inflammatory response following particle exposure.
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Affiliation(s)
- Andrew J Ghio
- Human Studies Facility, US Environmental Protection Agency, 104 Mason Farm Road, Chapel Hill, NC, 27599-7315, USA.
| | - Joleen M Soukup
- Human Studies Facility, US Environmental Protection Agency, 104 Mason Farm Road, Chapel Hill, NC, 27599-7315, USA
| | - Lisa A Dailey
- Human Studies Facility, US Environmental Protection Agency, 104 Mason Farm Road, Chapel Hill, NC, 27599-7315, USA
| | - Victor L Roggli
- Department of Pathology, Duke University Medical Center, Durham, NC, USA
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Ghio C, Soukup JM, Dailey LA, Ghio AJ, Schreinemachers DM, Koppes RA, Koppes AN. Lactate Production can Function to Increase Human Epithelial Cell Iron Concentration. Cell Mol Bioeng 2022; 15:571-585. [PMID: 36531860 PMCID: PMC9751240 DOI: 10.1007/s12195-022-00741-z] [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: 03/26/2022] [Accepted: 09/21/2022] [Indexed: 11/28/2022] Open
Abstract
Introduction Under conditions of limited iron availability, plants and microbes have evolved mechanisms to acquire iron. For example, metal deficiency stimulates reprogramming of carbon metabolism, increasing activity of enzymes involved in the Krebs cycle and the glycolytic pathway. Resultant carboxylates/hydroxycarboxylates then function as ligands to complex iron and facilitate solubilization and uptake, reversing the metal deficiency. Similarly, human intestinal epithelial cells may produce lactate, a hydroxycarboxylate, during absolute and functional iron deficiency to import metal to reverse limited availability. Methods Here we investigate (1) if lactate can increase cell metal import of epithelial cells in vitro, (2) if lactate dehydrogenase (LDH) activity in and lactate production by epithelial cells correspond to metal availability, and (3) if blood concentrations of LDH in a human cohort correlate with indices of iron homeostasis. Results Results show that exposures of human epithelial cells, Caco-2, to both sodium lactate and ferric ammonium citrate (FAC) increase metal import relative to FAC alone. Similarly, fumaric, isocitric, malic, and succinic acid coincubation with FAC increase iron import relative to FAC alone. Increased iron import following exposures to sodium lactate and FAC elevated both ferritin and metal associated with mitochondria. LDH did not change after exposure to deferoxamine but decreased with 24 h exposure to FAC. Lactate levels revealed decreased levels with FAC incubation. Review of the National Health and Nutrition Examination Survey demonstrated significant negative relationships between LDH concentrations and serum iron in human cohorts. Conclusions Therefore, we conclude that iron import in human epithelial cells can involve lactate, LDH activity can reflect the availability of this metal, and blood LDH concentrations can correlate with indices of iron homeostasis.
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Affiliation(s)
- Caroline Ghio
- Department of Chemical Engineering, Northeastern University, 360 Huntington Ave., 313 Snell Engineering, Boston, MA 02115 USA
| | | | - Lisa A. Dailey
- US Environmental Protection Agency, Chapel Hill, NC 27514 USA
| | - Andrew J. Ghio
- US Environmental Protection Agency, Chapel Hill, NC 27514 USA
| | | | - Ryan A. Koppes
- Department of Chemical Engineering, Northeastern University, 360 Huntington Ave., 313 Snell Engineering, Boston, MA 02115 USA
| | - Abigail N. Koppes
- Department of Chemical Engineering, Northeastern University, 360 Huntington Ave., 313 Snell Engineering, Boston, MA 02115 USA
- Department of Biology, Northeastern University, 360 Huntington Ave., 313 Snell Engineering, Boston, MA 02115 USA
- Department of Bioengineering, Northeastern University, 360 Huntington Ave., 313 Snell Engineering, Boston, MA 02115 USA
- Northeastern University, 360 Huntington Ave., 332 Mugar Life Science Building, Boston, MA 02115 USA
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Phummisutthigoon S, Lertsuwan K, Panupinthu N, Aeimlapa R, Teerapornpuntakit J, Chankamngoen W, Thongbunchoo J, Charoenphandhu N, Wongdee K. Fe3+ opposes the 1,25(OH)2D3-induced calcium transport across intestinal epithelium-like Caco-2 monolayer in the presence or absence of ascorbic acid. PLoS One 2022; 17:e0273267. [PMID: 36040915 PMCID: PMC9426938 DOI: 10.1371/journal.pone.0273267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/05/2022] [Indexed: 01/01/2023] Open
Abstract
Although iron is an essential element for hemoglobin and cytochrome synthesis, excessive intestinal iron absorption—as seen in dietary iron supplementation and hereditary disease called thalassemia—could interfere with transepithelial transport of calcium across the intestinal mucosa. The underlying cellular mechanism of iron-induced decrease in intestinal calcium absorption remains elusive, but it has been hypothesized that excess iron probably negates the actions of 1,25-dihydroxyvitamin D [1,25(OH)2D3]. Herein, we exposed the 1,25(OH)2D3-treated epithelium-like Caco-2 monolayer to FeCl3 to demonstrate the inhibitory effect of ferric ion on 1,25(OH)2D3-induced transepithelial calcium transport. We found that a 24-h exposure to FeCl3 on the apical side significantly decreased calcium transport, while increasing the transepithelial resistance (TER) in 1,25(OH)2D3-treated monolayer. The inhibitory action of FeCl3 was considered rapid since 60-min exposure was sufficient to block the 1,25(OH)2D3-induced decrease in TER and increase in calcium flux. Interestingly, FeCl3 did not affect the baseline calcium transport in the absence of 1,25(OH)2D3 treatment. Furthermore, although ascorbic acid is often administered to maximize calcium solubility and to enhance intestinal calcium absorption, it apparently had no effect on calcium transport across the FeCl3- and 1,25(OH)2D3-treated Caco-2 monolayer. In conclusion, apical exposure to ferric ion appeared to negate the 1,25(OH)2D3-stimulated calcium transport across the intestinal epithelium. The present finding has, therefore, provided important information for development of calcium and iron supplement products and treatment protocol for specific groups of individuals, such as thalassemia patients and pregnant women.
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Affiliation(s)
- Sukpapohn Phummisutthigoon
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kornkamon Lertsuwan
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Nattapon Panupinthu
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Ratchaneevan Aeimlapa
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jarinthorn Teerapornpuntakit
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Wasutorn Chankamngoen
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Graduate Program in Molecular Medicine, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jirawan Thongbunchoo
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Narattaphol Charoenphandhu
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
- The Academy of Science, The Royal Society of Thailand, Dusit, Bangkok, Thailand
- * E-mail:
| | - Kannikar Wongdee
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
- Faculty of Allied Health Sciences, Burapha University, Chonburi, Thailand
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Perfecto A, Elgy C, Valsami-Jones E, Sharp P, Hilty F, Fairweather-Tait S. Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells. Nutrients 2017; 9:nu9040359. [PMID: 28375175 PMCID: PMC5409698 DOI: 10.3390/nu9040359] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 03/27/2017] [Accepted: 03/30/2017] [Indexed: 12/28/2022] Open
Abstract
Food fortification programs to reduce iron deficiency anemia require bioavailable forms of iron that do not cause adverse organoleptic effects. Rodent studies show that nano-sized ferric phosphate (NP-FePO4) is as bioavailable as ferrous sulfate, but there is controversy over the mechanism of absorption. We undertook in vitro studies to examine this using a Caco-2 cell model and simulated gastrointestinal (GI) digestion. Supernatant iron concentrations increased inversely with pH, and iron uptake into Caco-2 cells was 2–3 fold higher when NP-FePO4 was digested at pH 1 compared to pH 2. The size and distribution of NP-FePO4 particles during GI digestion was examined using transmission electron microscopy. The d50 of the particle distribution was 413 nm. Using disc centrifugal sedimentation, a high degree of agglomeration in NP-FePO4 following simulated GI digestion was observed, with only 20% of the particles ≤1000 nm. In Caco-2 cells, divalent metal transporter-1 (DMT1) and endocytosis inhibitors demonstrated that NP-FePO4 was mainly absorbed via DMT1. Small particles may be absorbed by clathrin-mediated endocytosis and micropinocytosis. These findings should be considered when assessing the potential of iron nanoparticles for food fortification.
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Affiliation(s)
- Antonio Perfecto
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Christine Elgy
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Eugenia Valsami-Jones
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Paul Sharp
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Florentine Hilty
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Susan Fairweather-Tait
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
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Horniblow RD, Latunde-Dada GO, Harding SE, Schneider M, Almutairi FM, Sahni M, Bhatti A, Ludwig C, Norton IT, Iqbal TH, Tselepis C. The chelation of colonic luminal iron by a unique sodium alginate for the improvement of gastrointestinal health. Mol Nutr Food Res 2016; 60:2098-2108. [DOI: 10.1002/mnfr.201500882] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Richard D. Horniblow
- Institute of Cancer and Genomic Science; University of Birmingham; Edgbaston Birmingham UK
| | | | - Stephen E. Harding
- National Centre for Macromolecular Hydrodynamics; School of Biosciences; The University of Nottingham; Loughborough UK
| | - Melanie Schneider
- Institute of Cancer and Genomic Science; University of Birmingham; Edgbaston Birmingham UK
| | - Fahad M. Almutairi
- National Centre for Macromolecular Hydrodynamics; School of Biosciences; The University of Nottingham; Loughborough UK
| | - Manroy Sahni
- Institute of Cancer and Genomic Science; University of Birmingham; Edgbaston Birmingham UK
| | - Ahsan Bhatti
- Institute of Cancer and Genomic Science; University of Birmingham; Edgbaston Birmingham UK
| | - Christian Ludwig
- Institute of Cancer and Genomic Science; University of Birmingham; Edgbaston Birmingham UK
| | - Ian T. Norton
- School of Chemical Engineering; University of Birmingham; Edgbaston Birmingham UK
| | - Tariq H. Iqbal
- Institute of Cancer and Genomic Science; University of Birmingham; Edgbaston Birmingham UK
| | - Chris Tselepis
- Institute of Cancer and Genomic Science; University of Birmingham; Edgbaston Birmingham UK
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Horniblow RD, Dowle M, Iqbal TH, Latunde-Dada GO, Palmer RE, Pikramenou Z, Tselepis C. Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism. PLoS One 2015; 10:e0138240. [PMID: 26378798 PMCID: PMC4574481 DOI: 10.1371/journal.pone.0138240] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/27/2015] [Indexed: 11/18/2022] Open
Abstract
Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease.
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Affiliation(s)
- Richard D. Horniblow
- University of Birmingham, School of Cancer Sciences, College of Medical and Dental Sciences, Vincent Drive, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Miriam Dowle
- University of Birmingham, School of Physics, College of Engineering and Physical Sciences, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Tariq H. Iqbal
- University of Birmingham, School of Cancer Sciences, College of Medical and Dental Sciences, Vincent Drive, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Gladys O. Latunde-Dada
- Diabetes and Nutritional Sciences, King's College London, Franklin Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom
| | - Richard E. Palmer
- University of Birmingham, School of Physics, College of Engineering and Physical Sciences, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Zoe Pikramenou
- University of Birmingham, School of Chemistry, College of Engineering and Physical Sciences, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Chris Tselepis
- University of Birmingham, School of Cancer Sciences, College of Medical and Dental Sciences, Vincent Drive, Edgbaston, Birmingham, B15 2TT, United Kingdom
- * E-mail:
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Dietary iron intakes based on food composition data may underestimate the contribution of potentially exchangeable contaminant iron from soil. J Food Compost Anal 2015. [DOI: 10.1016/j.jfca.2014.11.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Wawer AA, Harvey LJ, Dainty JR, Perez-Moral N, Sharp P, Fairweather-Tait SJ. Alginate inhibits iron absorption from ferrous gluconate in a randomized controlled trial and reduces iron uptake into Caco-2 cells. PLoS One 2014; 9:e112144. [PMID: 25391138 PMCID: PMC4229116 DOI: 10.1371/journal.pone.0112144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 10/10/2014] [Indexed: 11/19/2022] Open
Abstract
UNLABELLED Previous in vitro results indicated that alginate beads might be a useful vehicle for food iron fortification. A human study was undertaken to test the hypothesis that alginate enhances iron absorption. A randomised, single blinded, cross-over trial was carried out in which iron absorption was measured from serum iron appearance after a test meal. Overnight-fasted volunteers (n = 15) were given a test meal of 200 g cola-flavoured jelly plus 21 mg iron as ferrous gluconate, either in alginate beads mixed into the jelly or in a capsule. Iron absorption was lower from the alginate beads than from ferrous gluconate (8.5% and 12.6% respectively, p = 0.003). Sub-group B (n = 9) consumed the test meals together with 600 mg calcium to determine whether alginate modified the inhibitory effect of calcium. Calcium reduced iron absorption from ferrous gluconate by 51%, from 11.5% to 5.6% (p = 0.014), and from alginate beads by 37%, from 8.3% to 5.2% (p = 0.009). In vitro studies using Caco-2 cells were designed to explore the reasons for the difference between the previous in vitro findings and the human study; confirmed the inhibitory effect of alginate. Beads similar to those used in the human study were subjected to simulated gastrointestinal digestion, with and without cola jelly, and the digestate applied to Caco-2 cells. Both alginate and cola jelly significantly reduced iron uptake into the cells, by 34% (p = 0.009) and 35% (p = 0.003) respectively. The combination of cola jelly and calcium produced a very low ferritin response, 16.5% (p < 0.001) of that observed with ferrous gluconate alone. The results of these studies demonstrate that alginate beads are not a useful delivery system for soluble salts of iron for the purpose of food fortification. TRIAL REGISTRATION ClinicalTrials.gov NCT01528644.
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Affiliation(s)
- Anna A. Wawer
- Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom
| | - Linda J. Harvey
- Institute of Food Research, Norwich, Norfolk, United Kingdom
| | - Jack R. Dainty
- Institute of Food Research, Norwich, Norfolk, United Kingdom
| | | | - Paul Sharp
- King's College London, London, United Kingdom
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Eagling T, Wawer AA, Shewry PR, Zhao FJ, Fairweather-Tait SJ. Iron bioavailability in two commercial cultivars of wheat: comparison between wholegrain and white flour and the effects of nicotianamine and 2'-deoxymugineic acid on iron uptake into Caco-2 cells. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:10320-5. [PMID: 25275535 DOI: 10.1021/jf5026295] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Iron bioavailability in unleavened white and wholegrain bread made from two commercial wheat varieties was assessed by measuring ferritin production in Caco-2 cells. The breads were subjected to simulated gastrointestinal digestion and the digests applied to the Caco-2 cells. Although Riband grain contained a lower iron concentration than Rialto, iron bioavailability was higher. No iron was taken up by the cells from white bread made from Rialto flour or from wholegrain bread from either variety, but Riband white bread produced a small ferritin response. The results probably relate to differences in phytate content of the breads, although iron in soluble monoferric phytate was demonstrated to be bioavailable in the cell model. Nicotianamine, an iron chelator in plants involved in iron transport, was a more potent enhancer of iron uptake into Caco-2 cells than ascorbic acid or 2'-deoxymugineic acid, another metal chelator present in plants.
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Affiliation(s)
- Tristan Eagling
- Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom
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Christides T, Sharp P. Sugars increase non-heme iron bioavailability in human epithelial intestinal and liver cells. PLoS One 2013; 8:e83031. [PMID: 24340076 PMCID: PMC3858368 DOI: 10.1371/journal.pone.0083031] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 10/30/2013] [Indexed: 12/21/2022] Open
Abstract
Previous studies have suggested that sugars enhance iron bioavailability, possibly through either chelation or altering the oxidation state of the metal, however, results have been inconclusive. Sugar intake in the last 20 years has increased dramatically, and iron status disorders are significant public health problems worldwide; therefore understanding the nutritional implications of iron-sugar interactions is particularly relevant. In this study we measured the effects of sugars on non-heme iron bioavailability in human intestinal Caco-2 cells and HepG2 hepatoma cells using ferritin formation as a surrogate marker for iron uptake. The effect of sugars on iron oxidation state was examined by measuring ferrous iron formation in different sugar-iron solutions with a ferrozine-based assay. Fructose significantly increased iron-induced ferritin formation in both Caco-2 and HepG2 cells. In addition, high-fructose corn syrup (HFCS-55) increased Caco-2 cell iron-induced ferritin; these effects were negated by the addition of either tannic acid or phytic acid. Fructose combined with FeCl3 increased ferrozine-chelatable ferrous iron levels by approximately 300%. In conclusion, fructose increases iron bioavailability in human intestinal Caco-2 and HepG2 cells. Given the large amount of simple and rapidly digestible sugars in the modern diet their effects on iron bioavailability may have important patho-physiological consequences. Further studies are warranted to characterize these interactions.
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Affiliation(s)
- Tatiana Christides
- University of Greenwich, Faculty of Engineering & Science, Department of Life & Sports Science, Chatham Maritime, United Kingdom
| | - Paul Sharp
- King’s College London, Diabetes & Nutritional Sciences Division, School of Medicine, London, United Kingdom
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