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Sakurai-Yageta M, Suzuki Y. Molecular Mechanisms of Biotin in Modulating Inflammatory Diseases. Nutrients 2024; 16:2444. [PMID: 39125325 PMCID: PMC11314543 DOI: 10.3390/nu16152444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Revised: 07/23/2024] [Accepted: 07/24/2024] [Indexed: 08/12/2024] Open
Abstract
Biotin, also known as vitamin B7 or vitamin H, is a water-soluble B-complex vitamin and serves as an essential co-enzyme for five specific carboxylases. Holocarboxylase synthase (HCS) activates biotin and facilitates its covalent attachment to these enzymes, while biotinidase releases free biotin in the biotin cycle. The transport of biotin, primarily from the intestine, is mediated by the sodium-dependent multi-vitamin transporter (SMVT). Severe biotin deficiency leads to multiple carboxylase deficiency. Moreover, biotin is crucial to glucose and lipid utilization in cellular energy production because it modulates the expression of metabolic enzymes via various signaling pathways and transcription factors. Biotin also modulates the production of proinflammatory cytokines in the immune system through similar molecular mechanisms. These regulatory roles in metabolic and immune homeostasis connect biotin to conditions such as diabetes, dermatologic manifestations, and multiple sclerosis. Furthermore, deficiencies in biotin and SMVT are implicated in inflammatory bowel disease, affecting intestinal inflammation, permeability, and flora. Notably, HCS and probably biotin directly influence gene expression through histone modification. In this review, we summarize the current knowledge on the molecular aspects of biotin and associated molecules in diseases related to both acute inflammatory responses and chronic inflammation, and discuss the potential therapeutic applications of biotin.
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Affiliation(s)
- Mika Sakurai-Yageta
- Department of Education and Training, Tohoku Medical Megabank Organization, Tohoku University, Sendai 980-8573, Miyagi, Japan
- Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai 980-8573, Miyagi, Japan
| | - Yoichi Suzuki
- Department of Education and Training, Tohoku Medical Megabank Organization, Tohoku University, Sendai 980-8573, Miyagi, Japan
- Department of Clinical Genetics, Ageo Central General Hospital, Ageo 362-8588, Saitama, Japan
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2
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Erbach J, Bonn F, Diesner M, Arnold A, Stein J, Schröder O, Aksan A. Relevance of Biotin Deficiency in Patients with Inflammatory Bowel Disease and Utility of Serum 3 Hydroxyisovaleryl Carnitine as a Practical Everyday Marker. J Clin Med 2022; 11:jcm11041118. [PMID: 35207391 PMCID: PMC8877558 DOI: 10.3390/jcm11041118] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 02/13/2022] [Accepted: 02/15/2022] [Indexed: 02/04/2023] Open
Abstract
Background: Biotin, a water-soluble B vitamin, has demonstrable anti-inflammatory properties. A biotin-deficient diet induced a colitis-like phenotype in mice, alleviable by biotin substitution. Mice with dextran sulfate sodium (DSS)-induced colitis showed biotin deficiency and diminished levels of sodium-dependent multivitamin transporter, a protein involved in biotin absorption. Biotin substitution induced remission by reducing activation of NF-κB, a transcription factor involved in intestinal permeability and inflammatory bowel disease (IBD). We investigated for the first time a possible clinical role of biotin status in IBD. Methods: In a comparative, retrospective, cross-sectional study, serum samples of 138 patients with IBD (67 female; 72 Crohn’s disease (CD), 66 ulcerative colitis (UC)) aged 18–65 years and with a mean age (±SD) of 42.5 ± 14.3 years as well as 80 healthy blood donors (40 female; 40.0 ± 10.0 years; range 20–60 years) were analyzed. Inflammation was defined as hsCRP ≥5 mg/L, and to determine biotin status, serum 3-hydroxyisovaleryl carnitine (3HIVc) levels were measured by LC-MS/MS. Results: A total of 138 patients with IBD (67f; 72CD/66 UC; 42.5 ± 14.3 years) were enrolled: 83/138 had inflammation. Mean serum 3HIVc levels were significantly higher in IBD patients but unaffected by inflammation. Biotin deficiency (95th percentile of controls: >30 nmol/L 3HIVc) was significantly more common in IBD patients versus controls. Conclusion: High serum 3HIVc levels and biotin deficiency were associated with IBD but not inflammatory activity or disease type. Our findings suggest biotin may play a role as cause or effect in IBD pathogenesis. Routine assessment and supplementation of biotin may ameliorate IBD and support intestinal integrity.
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Affiliation(s)
- Johanna Erbach
- Interdisciplinary Crohn Colitis Center Rhein-Main, 60594 Frankfurt am Main, Germany; (J.E.); (O.S.); (A.A.)
| | - Florian Bonn
- Immundiagnostik AG, 64625 Bensheim, Germany; (F.B.); (M.D.); (A.A.)
| | - Max Diesner
- Immundiagnostik AG, 64625 Bensheim, Germany; (F.B.); (M.D.); (A.A.)
| | - Anne Arnold
- Immundiagnostik AG, 64625 Bensheim, Germany; (F.B.); (M.D.); (A.A.)
| | - Jürgen Stein
- Interdisciplinary Crohn Colitis Center Rhein-Main, 60594 Frankfurt am Main, Germany; (J.E.); (O.S.); (A.A.)
- DGD Kliniken Sachsenhausen, 60594 Frankfurt am Main, Germany
- Institute of Pharmaceutical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
- Correspondence:
| | - Oliver Schröder
- Interdisciplinary Crohn Colitis Center Rhein-Main, 60594 Frankfurt am Main, Germany; (J.E.); (O.S.); (A.A.)
- DGD Kliniken Sachsenhausen, 60594 Frankfurt am Main, Germany
| | - Ayşegül Aksan
- Interdisciplinary Crohn Colitis Center Rhein-Main, 60594 Frankfurt am Main, Germany; (J.E.); (O.S.); (A.A.)
- Institute of Nutritional Science, Justus-Liebig University, 35392 Giessen, Germany
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3
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Exploring the Immune-Boosting Functions of Vitamins and Minerals as Nutritional Food Bioactive Compounds: A Comprehensive Review. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27020555. [PMID: 35056870 PMCID: PMC8779769 DOI: 10.3390/molecules27020555] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/04/2022] [Accepted: 01/10/2022] [Indexed: 02/06/2023]
Abstract
Food components have long been recognized to play a fundamental role in the growth and development of the human body, conferring protective functionalities against foreign matter that can be severe public health problems. Micronutrients such as vitamins and minerals are essential to the human body, and individuals must meet their daily requirements through dietary sources. Micronutrients act as immunomodulators and protect the host immune response, thus preventing immune evasion by pathogenic organisms. Several experimental investigations have been undertaken to appraise the immunomodulatory functions of vitamins and minerals. Based on these experimental findings, this review describes the immune-boosting functionalities of micronutrients and the mechanisms of action through which these functions are mediated. Deficiencies of vitamins and minerals in plasma concentrations can lead to a reduction in the performance of the immune system functioning, representing a key contributor to unfavorable immunological states. This review provides a descriptive overview of the characteristics of the immune system and the utilization of micronutrients (vitamins and minerals) in preventative strategies designed to reduce morbidity and mortality among patients suffering from immune invasions or autoimmune disorders.
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Sakurai-Yageta M, Mashimo Y, Kuroishi T, Ishihara R, Shimojo N, Kohno Y, Okamoto Y, Hata A, Suzuki Y. Association between Serum Biotin Levels and Cedar Pollinosis in Japanese Schoolchildren. J Nutr Sci Vitaminol (Tokyo) 2021; 67:211-216. [PMID: 34470995 DOI: 10.3177/jnsv.67.211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Biotin is a water-soluble B complex vitamin and coenzyme of five types of carboxylase and plays crucial roles in fatty acid, glucose, and amino acid metabolism. Nutritional biotin deficiency and defective enzymes essential for biotin metabolism cause inflammatory diseases such as eczema-like dermatitis and Crohn's disease; however, little is known about the pathophysiological roles of biotin. This study investigated the relationship between biotin metabolism and human allergic sensitization and diseases by measuring serum levels of biotin, total immunoglobulin E (IgE) and allergen-specific IgEs in more than 400 Japanese schoolchildren aged 6 to 12. The prevalence of allergic diseases, and environmental and life-style factors were also examined by a questionnaire. Like total IgE, serum biotin levels of children showed a log-normal distribution. Meanwhile, Spearman's rank correlation analysis showed weak but significant positive associations between serum biotin levels and total IgE (rho=0.147, p=0.0029) as well as allergen-specific IgEs against egg whites (rho=0.215, p=0.00013), cedar pollen (rho=0.176, p=0.00036), and cat dander (rho=0.130, p=0.0085). Furthermore, mean serum biotin levels in children with cedar pollinosis, but not with other allergic diseases such as asthma and allergic rhinitis, were significantly higher than in those without (p=0.0015). These results suggest a correlation between serum biotin levels and the development of cedar pollinosis. Further prospective studies are needed to evaluate the causal relationship between biotin metabolism and cedar pollen sensitization and pollinosis development.
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Affiliation(s)
- Mika Sakurai-Yageta
- Department of Education and Training, Tohoku Medical Megabank Organization, Tohoku University
| | - Yoichi Mashimo
- Department of Public Health, Graduate School of Medicine, Chiba University
| | - Toshinobu Kuroishi
- Division of Oral Immunology, Tohoku University Graduate School of Dentistry, Tohoku University
| | - Rino Ishihara
- Department of Education and Training, Tohoku Medical Megabank Organization, Tohoku University
| | - Naoki Shimojo
- Department of Pediatrics, Graduate School of Medicine, Chiba University.,Center for Preventive Medical Sciences, Chiba University
| | - Yoichi Kohno
- Department of Pediatrics, Graduate School of Medicine, Chiba University.,Chiba Rosai Hospital
| | - Yoshitaka Okamoto
- Chiba Rosai Hospital.,Department of Otorhinolaryngology and Head and Neck Surgery, Graduate School of Medicine, Chiba University
| | - Akira Hata
- Department of Public Health, Graduate School of Medicine, Chiba University
| | - Yoichi Suzuki
- Department of Education and Training, Tohoku Medical Megabank Organization, Tohoku University.,Department of Public Health, Graduate School of Medicine, Chiba University
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5
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Ramamoorthy K, Sabui S, Srinivasan P, Al-Juburi S, Pham Q, Chu BD, Simoes RD, Fleckenstein JM, Said HM. Effect of chronic alcohol exposure on gut vitamin B7 uptake: involvement of epigenetic mechanisms and effect of alcohol metabolites. Am J Physiol Gastrointest Liver Physiol 2021; 321:G123-G133. [PMID: 34077272 PMCID: PMC8410103 DOI: 10.1152/ajpgi.00144.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Vitamin B7 (biotin) is essential for normal health and its deficiency/suboptimal levels occur in a variety of conditions including chronic alcoholism. Mammals, including humans, obtain biotin from diet and gut-microbiota via absorption along the intestinal tract. The absorption process is carrier mediated and involves the sodium-dependent multivitamin transporter (SMVT; SLC5A6). We have previously shown that chronic alcohol exposure significantly inhibits intestinal/colonic biotin uptake via suppression of Slc5a6 transcription in animal and cell line models. However, little is known about the transcriptional/epigenetic factors that mediate this suppression. In addition, the effect of alcohol metabolites (generated via alcohol metabolism by gut microbiota and host tissues) on biotin uptake is still unknown. To address these questions, we first demonstrated that chronic alcohol exposure inhibits small intestinal and colonic biotin uptake and SMVT expression in human differentiated enteroid and colonoid monolayers. We then showed that chronic alcohol exposures of both, Caco-2 cells and mice, are associated with a significant suppression in expression of the nuclear factor KLF-4 (needed for Slc5a6 promoter activity), as well as with epigenetic alterations (histone modifications). We also found that chronic exposure of NCM460 human colonic epithelial cells as well as human differentiated colonoid monolayers, to alcohol metabolites (acetaldehyde, ethyl palmitate, ethyl oleate) significantly inhibited biotin uptake and SMVT expression. These findings shed light onto the molecular/epigenetic mechanisms that mediate the inhibitory effect of chronic alcohol exposure on intestinal biotin uptake. They further show that alcohol metabolites are also capable of inhibiting biotin uptake in the gut.NEW & NOTEWORTHY Using complementary models, including human differentiated enteroid and colonoid monolayers, this study shows the involvement of molecular and epigenetic mechanisms in mediating the inhibitory effect of chronic alcohol exposure on biotin uptake along the intestinal tract. The study also shows that alcohol metabolites (generated by gut microbiota and host tissues) cause inhibition in gut biotin uptake.
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Affiliation(s)
- Kalidas Ramamoorthy
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Subrata Sabui
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Padmanabhan Srinivasan
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Saleh Al-Juburi
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Quang Pham
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Brian D. Chu
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Rita D. Simoes
- 3Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - James M. Fleckenstein
- 3Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri,4Veterans Affairs Medical Center, St. Louis Missouri
| | - Hamid M. Said
- 1Department of Physiology/Biophysics, University of California, Irvine, California,2Department of Medicine, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
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6
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Kuroishi T, Sugawara S. Metabolomic Analysis of Liver from Dietary Biotin Deficient Mice. J Nutr Sci Vitaminol (Tokyo) 2020; 66:82-85. [PMID: 32115458 DOI: 10.3177/jnsv.66.82] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Biotin is a water-soluble B-complex vitamin that functions as a cofactor of five carboxylases. Because biotin-dependent carboxylases catalyze indispensable cellular metabolic functions, biotin deficiency is considered to be involved in various pathological conditions. Moreover, biotin supplementation shows pharmacological effects in vivo. However, the precise mechanisms by which biotin deficiency induces pathological conditions remain unclear. Although abnormal metabolites are used as indicators for biotin deficiency, few comprehensive analyses of total metabolites have been reported. In this study, we analyzed the metabolomic profiles of liver extracts prepared from biotin-sufficient (BS) and -deficient (BD) mice. Thirteen of 126 metabolites showed significantly different concentrations between liver extracts from BD and BS mice. The concentrations of 5 essential amino acids, Met, Val, Thr, Ile, and Leu, and 2 conditionally essential amino acids, Cys and Tyr were significantly lower in BD mice than in BS mice. Among these, the concentrations of sulfur-containing amino acids, Cys and Met, were more than 1.5-fold lower in BD mice. The concentrations of Met metabolites, such as S-adenosylmethionine and S-adenosylhomocysteine were not significantly different between the two groups. The concentrations of glutathione and its reaction intermediates γ-Glu-Cys tendency to be lower in BD mice. The present study revealed that biotin deficiency induces an abnormal amino acids composition, especially among sulfur-containing amino acids and provide important information on the effect of biotin as a pharmacological agent.
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Affiliation(s)
- Toshinobu Kuroishi
- Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry
| | - Shunji Sugawara
- Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry
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7
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Sabui S, Skupsky J, Kapadia R, Cogburn K, Lambrecht NW, Agrawal A, Said HM. Tamoxifen-induced, intestinal-specific deletion of Slc5a6 in adult mice leads to spontaneous inflammation: involvement of NF-κB, NLRP3, and gut microbiota. Am J Physiol Gastrointest Liver Physiol 2019; 317:G518-G530. [PMID: 31369292 PMCID: PMC6842991 DOI: 10.1152/ajpgi.00172.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The sodium-dependent multivitamin transporter (SMVT; SLC5A6) is involved in intestinal absorption of vitamin B7 (biotin). We have previously shown that mice with an embryonic intestinal-specific SMVT knockout (KO) develop biotin deficiency and severe spontaneous intestinal inflammation in addition to growth retardation, developmental delays, and death within the first 6-7 wk of life. The profound morbidity and mortality associated with the SMVT-KO has limited our ability to further characterize the intestinal inflammation and other sequelae of this deletion in adult mice with a mature gut microbiota. To overcome this limitation, we generated an intestine-specific, tamoxifen-inducible, conditional SMVT-KO (SMVT-icKO). Our results showed that adult SMVT-icKO mice have reduced body weight, biotin deficiency, shorter colonic length, and bloody diarrhea compared with age- and sex-matched control littermates. All SMVT-icKO mice also developed spontaneous intestinal inflammation associated with induction of calprotectin (S100a8/S100a9), proinflammatory cytokines (IL-1β, TNF-α, IFN-γ, and IL-6), and an increase in intestinal permeability. Additionally, the intestines of SMVT-icKO showed activation of the NF-κB pathway and the nucleotide-binding domain and leucine-rich repeat pyrin 3 domain (NLRP3) inflammasome. Notably, administration of broad-spectrum antibiotics reduced lethality and led to normalization of intestinal inflammation, proinflammatory cytokines, altered mucosal integrity, and reduced expression of the NLRP3 inflammasome. Overall, these findings support our conclusion that the biotin transport pathway plays an important role in the maintenance of intestinal homeostasis, and that NF-κB and the NLRP3 inflammasome, as well as gut microbiota, drive the development of intestinal inflammation when SMVT is absent.NEW & NOTEWORTHY This study demonstrates that deletion of the intestinal biotin uptake system in adult mice leads to the development of spontaneous gut inflammation and that luminal microbiota plays a role in its development.
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Affiliation(s)
- Subrata Sabui
- 1Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California,3Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
| | - Jonathan Skupsky
- 2Department of Medicine, School of Medicine, University of California, Irvine, California,3Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
| | - Rubina Kapadia
- 2Department of Medicine, School of Medicine, University of California, Irvine, California,3Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
| | - Kyle Cogburn
- 1Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
| | - Nils W. Lambrecht
- 3Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
| | - Anshu Agrawal
- 2Department of Medicine, School of Medicine, University of California, Irvine, California
| | - Hamid M. Said
- 1Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California,2Department of Medicine, School of Medicine, University of California, Irvine, California,3Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California
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Abstract
Nine compounds are classified as water-soluble vitamins, eight B vitamins and one vitamin C. The vitamins are mandatory for the function of numerous enzymes and lack of one or more of the vitamins may lead to severe medical conditions. All the vitamins are supplied by food in microgram to milligram quantities and in addition some of the vitamins are synthesized by the intestinal microbiota. In the gastrointestinal tract, the vitamins are liberated from binding proteins and for some of the vitamins modified prior to absorption. Due to their solubility in water, they all require specific carriers to be absorbed. Our current knowledge concerning each of the vitamins differs in depth and focus and is influenced by the prevalence of conditions and diseases related to lack of the individual vitamin. Because of that we have chosen to cover slightly different aspects for the individual vitamins. For each of the vitamins, we summarize the physiological role, the steps involved in the absorption, and the factors influencing the absorption. In addition, for some of the vitamins, the molecular base for absorption is described in details, while for others new aspects of relevance for human deficiency are included. © 2018 American Physiological Society. Compr Physiol 8:1291-1311, 2018.
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Affiliation(s)
- Hamid M Said
- University of California-School of Medicine, Irvine, California, USA.,VA Medical Center, Long Beach, California, USA
| | - Ebba Nexo
- Department of Clinical Medicine, Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
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9
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Lakhan R, Said HM. Lipopolysaccharide inhibits colonic biotin uptake via interference with membrane expression of its transporter: a role for a casein kinase 2-mediated pathway. Am J Physiol Cell Physiol 2017; 312:C376-C384. [PMID: 28052864 DOI: 10.1152/ajpcell.00300.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/30/2016] [Accepted: 01/03/2017] [Indexed: 12/13/2022]
Abstract
Biotin (vitamin B7), an essential micronutrient for normal cellular functions, is obtained from both dietary sources as well as gut microbiota. Absorption of biotin in both the small and large intestine is via a carrier-mediated process that involves the sodium-dependent multivitamin transporter (SMVT). Although different physiological and molecular aspects of intestinal biotin uptake have been delineated, nothing is known about the effect of LPS on the process. We addressed this issue using in vitro (human colonic epithelial NCM460 cells) and in vivo (mice) models of LPS exposure. Treating NCM460 cells with LPS was found to lead to a significant inhibition in carrier-mediated biotin uptake. Similarly, administration of LPS to mice led to a significant inhibition in biotin uptake by native colonic tissue. Although no changes in total cellular SMVT protein and mRNA levels were observed, LPS caused a decrease in the fraction of SMVT expressed at the cell surface. A role for casein kinase 2 (CK2) (whose activity was also inhibited by LPS) in mediating the endotoxin effects on biotin uptake and on membrane expression of SMVT was suggested by findings that specific inhibitors of CK2, as well as mutating the putative CK2 phosphorylation site (Thr78Ala) in the SMVT protein, led to inhibition in biotin uptake and membrane expression of SMVT. This study shows for the first time that LPS inhibits colonic biotin uptake via decreasing membrane expression of its transporter and that these effects likely involve a CK2-mediated pathway.
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Affiliation(s)
- Ram Lakhan
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Medical Research, VA Medical Center, Long Beach, California
| | - Hamid M Said
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Medical Research, VA Medical Center, Long Beach, California
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10
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Sabui S, Bohl JA, Kapadia R, Cogburn K, Ghosal A, Lambrecht NW, Said HM. Role of the sodium-dependent multivitamin transporter (SMVT) in the maintenance of intestinal mucosal integrity. Am J Physiol Gastrointest Liver Physiol 2016; 311:G561-70. [PMID: 27492331 PMCID: PMC5076003 DOI: 10.1152/ajpgi.00240.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/25/2016] [Indexed: 02/07/2023]
Abstract
Utilizing a conditional (intestinal-specific) knockout (cKO) mouse model, we have recently shown that the sodium-dependent multivitamin transporter (SMVT) (SLC5A6) is the only biotin uptake system that operates in the gut and that its deletion leads to biotin deficiency. Unexpectedly, we also observed that all SMVT-cKO mice develop chronic active inflammation, especially in the cecum. Our aim here was to examine the role of SMVT in the maintenance of intestinal mucosal integrity [permeability and expression of tight junction (TJ) proteins]. Our results showed that knocking out the mouse intestinal SMVT is associated with a significant increase in gut permeability and with changes in the level of expression of TJ proteins. To determine whether these changes are related to the state of biotin deficiency that develops in SMVT-cKO mice, we induced (by dietary means) biotin deficiency in wild-type mice and examined its effect on the above-mentioned parameters. The results showed that dietary-induced biotin deficiency leads to a similar development of chronic active inflammation in the cecum with an increase in the level of expression of proinflammatory cytokines, as well as an increase in intestinal permeability and changes in the level of expression of TJ proteins. We also examined the effect of chronic biotin deficiency on permeability and expression of TJ proteins in confluent intestinal epithelial Caco-2 monolayers but observed no changes in these parameters. These results show that the intestinal SMVT plays an important role in the maintenance of normal mucosal integrity, most likely via its role in providing biotin to different cells of the gut mucosa.
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Affiliation(s)
- Subrata Sabui
- 1Department of Medical Research, VA Medical Center, Long Beach, California; ,2Departments of Medicine, University of California, Irvine, California; ,3Department of Physiology/Biophysics, University of California, Irvine, California
| | - Jennifer Ann Bohl
- 1Department of Medical Research, VA Medical Center, Long Beach, California; ,2Departments of Medicine, University of California, Irvine, California; ,3Department of Physiology/Biophysics, University of California, Irvine, California
| | - Rubina Kapadia
- 1Department of Medical Research, VA Medical Center, Long Beach, California; ,2Departments of Medicine, University of California, Irvine, California; ,3Department of Physiology/Biophysics, University of California, Irvine, California
| | - Kyle Cogburn
- 1Department of Medical Research, VA Medical Center, Long Beach, California; ,2Departments of Medicine, University of California, Irvine, California; ,3Department of Physiology/Biophysics, University of California, Irvine, California
| | - Abhisek Ghosal
- 1Department of Medical Research, VA Medical Center, Long Beach, California; ,2Departments of Medicine, University of California, Irvine, California; ,3Department of Physiology/Biophysics, University of California, Irvine, California
| | - Nils W. Lambrecht
- 1Department of Medical Research, VA Medical Center, Long Beach, California; ,2Departments of Medicine, University of California, Irvine, California; ,3Department of Physiology/Biophysics, University of California, Irvine, California
| | - Hamid M. Said
- 1Department of Medical Research, VA Medical Center, Long Beach, California; ,2Departments of Medicine, University of California, Irvine, California; ,3Department of Physiology/Biophysics, University of California, Irvine, California
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11
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Agrawal S, Agrawal A, Said HM. Biotin deficiency enhances the inflammatory response of human dendritic cells. Am J Physiol Cell Physiol 2016; 311:C386-91. [PMID: 27413170 DOI: 10.1152/ajpcell.00141.2016] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/12/2016] [Indexed: 12/24/2022]
Abstract
The water-soluble biotin (vitamin B7) is indispensable for normal human health. The vitamin acts as a cofactor for five carboxylases that are critical for fatty acid, glucose, and amino acid metabolism. Biotin deficiency is associated with various diseases, and mice deficient in this vitamin display enhanced inflammation. Previous studies have shown that biotin affects the functions of adaptive immune T and NK cells, but its effect(s) on innate immune cells is not known. Because of that and because vitamins such as vitamins A and D have a profound effect on dendritic cell (DC) function, we investigated the effect of biotin levels on the functions of human monocyte-derived DCs. Culture of DCs in a biotin-deficient medium (BDM) and subsequent activation with LPS resulted in enhanced secretion of the proinflammatory cytokines TNF-α, IL-12p40, IL-23, and IL-1β compared with LPS-activated DCs cultured in biotin-sufficient (control) and biotin-oversupplemented media. Furthermore, LPS-activated DCs cultured in BDM displayed a significantly higher induction of IFN-γ and IL-17 indicating Th1/Th17 bias in T cells compared with cells maintained in biotin control or biotin-oversupplemented media. Investigations into the mechanisms suggested that impaired activation of AMP kinase in DCs cultured in BDM may be responsible for the observed increase in inflammatory responses. In summary, these results demonstrate for the first time that biotin deficiency enhances the inflammatory responses of DCs. This may therefore be one of the mechanism(s) that mediates the observed inflammation that occurs in biotin deficiency.
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Affiliation(s)
- Sudhanshu Agrawal
- Division of Basic and Clinical Immunology, Department of Medicine, University of California, Irvine, California
| | - Anshu Agrawal
- Division of Basic and Clinical Immunology, Department of Medicine, University of California, Irvine, California;
| | - Hamid M Said
- Department of Medicine, Department of Physiology and Biophysics, University of California, Irvine, California; and Veterans Affairs Medical Center-151, Long Beach, California
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Ghosal A, Jellbauer S, Kapadia R, Raffatellu M, Said HM. Salmonella infection inhibits intestinal biotin transport: cellular and molecular mechanisms. Am J Physiol Gastrointest Liver Physiol 2015; 309:G123-31. [PMID: 25999427 PMCID: PMC4504957 DOI: 10.1152/ajpgi.00112.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 05/13/2015] [Indexed: 01/31/2023]
Abstract
Infection with the nontyphoidal Salmonella is a common cause of food-borne disease that leads to acute gastroenteritis/diarrhea. Severe/prolonged cases of Salmonella infection could also impact host nutritional status, but little is known about its effect on intestinal absorption of vitamins, including biotin. We examined the effect of Salmonella enterica serovar Typhimurium (S. typhimurium) infection on intestinal biotin uptake using in vivo (streptomycin-pretreated mice) and in vitro [mouse (YAMC) and human (NCM460) colonic epithelial cells, and human intestinal epithelial Caco-2 cells] models. The results showed that infecting mice with wild-type S. typhimurium, but not with its nonpathogenic isogenic invA spiB mutant, leads to a significant inhibition in jejunal/colonic biotin uptake and in level of expression of the biotin transporter, sodium-dependent multivitamin transporter. In contrast, infecting YAMC, NCM460, and Caco-2 cells with S. typhimurium did not affect biotin uptake. These findings suggest that the effect of S. typhimurium infection is indirect and is likely mediated by proinflammatory cytokines, the levels of which were markedly induced in the intestine of S. typhimurium-infected mice. Consistent with this hypothesis, exposure of NCM460 cells to the proinflammatory cytokines TNF-α and IFN-γ led to a significant inhibition of biotin uptake, sodium-dependent multivitamin transporter expression, and activity of the SLC5A6 promoter. The latter effects appear to be mediated, at least in part, via the NF-κB signaling pathway. These results demonstrate that S. typhimurium infection inhibits intestinal biotin uptake, and that the inhibition is mediated via the action of proinflammatory cytokines.
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Affiliation(s)
- Abhisek Ghosal
- 1Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California;
| | - Stefan Jellbauer
- 3Department of Microbiology and Molecular Genetics, University of California, Irvine, California; and ,4Institute for Immunology, University of California, Irvine, California
| | - Rubina Kapadia
- 1Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California;
| | - Manuela Raffatellu
- 3Department of Microbiology and Molecular Genetics, University of California, Irvine, California; and ,4Institute for Immunology, University of California, Irvine, California
| | - Hamid M. Said
- 1Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; ,2Department of Veterans Affairs Medical Center, Long Beach, California;
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Dakshinamurti K. Vitamins and their derivatives in the prevention and treatment of metabolic syndrome diseases (diabetes),. Can J Physiol Pharmacol 2015; 93:355-62. [DOI: 10.1139/cjpp-2014-0479] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A cluster of inter-related conditions such as central obesity, dyslipidemia, impaired glucose metabolism, and hypertension is referred to as Metabolic Syndrome, which is a risk factor for the development of type-2 diabetes. The micro- and macro-vascular complications of diabetes contribute to its morbidity and mortality. In addition to its calcitropic effect, vitamin D is a regulator of gene expression as well as cell proliferation and differentiation. Various cross-sectional and longitudinal cohort studies have indicated a beneficial effect from vitamin D supplementation on the development of type-2 diabetes. Binding of retinol-bound retinol-binding protein to a membrane-binding protein suppresses insulin signaling. All-trans retinoic acid, a derivative of vitamin A, reverses these effects, resulting in increased insulin sensitivity, suppression of the phosphoenolpyruvate carboxy kinase (PEPCK) gene, and the induction of the glucokinase gene. Glucokinase and PEPCK are also regulated in opposite directions by the vitamin biotin, acting at the transcriptional level. Biotin also regulates the synthesis of insulin by the islet of Langerhans cells of the pancreas. The increase in advanced glycation end products (AGEs) is implicated in the initiation and progression of diabetes-associated microvascular diseases. Benfotiamine, a derivative of thiamine, and pyridoxamine, a vitamer of vitamin B6, both have anti-AGE properties, making them valuable therapeutic adjuvants in the treatment of diabetic complications. Thus, various vitamins and their derivatives have profound therapeutic potential in the prevention and treatment of type-2 diabetes.
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Affiliation(s)
- Krishnamurti Dakshinamurti
- St. Boniface Hospital Research Centre, Faculty of Medicine, University of Manitoba, 351 Tache Avenue Winnipeg, MB R2H 2A6, Canada
- St. Boniface Hospital Research Centre, Faculty of Medicine, University of Manitoba, 351 Tache Avenue Winnipeg, MB R2H 2A6, Canada
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Abstract
Biotin is a water-soluble B-complex vitamin and is well-known as a co-factor for 5 indispensable carboxylases. Holocarboxylase synthetase (HLCS) catalyzes the biotinylation of carboxylases and other proteins, whereas biotinidase catalyzes the release of biotin from biotinylated peptides. Previous studies have reported that nutritional biotin deficiency and genetic defects in either HLCS or biotinidase induces cutaneous inflammation and immunological disorders. Since biotin-dependent carboxylases involve various cellular metabolic pathways including gluconeogenesis, fatty acid synthesis, and the metabolism of branched-chain amino acids and odd-chain fatty acids, metabolic abnormalities may play important roles in immunological and inflammatory disorders caused by biotin deficiency. Transcriptional factors, including NF-κB and Sp1/3, are also affected by the status of biotin, indicating that biotin regulates immunological and inflammatory functions independently of biotin-dependent carboxylases. An in-vivo analysis with a murine model revealed the therapeutic effects of biotin supplementation on metal allergies. The novel roles of biotinylated proteins and their related enzymes have recently been reported. Non-carboxylase biotinylated proteins induce chemokine production. HLCS is a nuclear protein involved in epigenetic and chromatin regulation. In this review, comprehensive knowledge on the regulation of immunological and inflammatory functions by biotin and its potential as a therapeutic agent is discussed.
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Affiliation(s)
- Toshinobu Kuroishi
- Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.,Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
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Srinivasan P, Kapadia R, Biswas A, Said HM. Chronic alcohol exposure inhibits biotin uptake by pancreatic acinar cells: possible involvement of epigenetic mechanisms. Am J Physiol Gastrointest Liver Physiol 2014; 307:G941-9. [PMID: 25214397 PMCID: PMC4250263 DOI: 10.1152/ajpgi.00278.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 09/04/2014] [Indexed: 01/31/2023]
Abstract
Chronic exposure to alcohol affects different physiological aspects of pancreatic acinar cells (PAC), but its effect on the uptake process of biotin is not known. We addressed this issue using mouse-derived pancreatic acinar 266-6 cells chronically exposed to alcohol and wild-type and transgenic mice (carrying the human SLC5A6 5'-promoter) fed alcohol chronically. First we established that biotin uptake by PAC is Na(+) dependent and carrier mediated and involves sodium-dependent multivitamin transporter (SMVT). Chronic exposure of 266-6 cells to alcohol led to a significant inhibition in biotin uptake, expression of SMVT protein, and mRNA as well as in the activity of the SLC5A6 promoter. Similarly, chronic alcohol feeding of wild-type and transgenic mice carrying the SLC5A6 promoter led to a significant inhibition in biotin uptake by PAC, as well as in the expression of SMVT protein and mRNA and the activity of the SLC5A6 promoters expressed in the transgenic mice. We also found that chronic alcohol feeding of mice is associated with a significant increase in the methylation status of CpG islands predicted to be in the mouse Slc5a6 promoters and a decrease in the level of expression of transcription factor KLF-4, which plays an important role in regulating SLC5A6 promoter activity. These results demonstrate, for the first time, that chronic alcohol exposure negatively impacts biotin uptake in PAC and that this effect is exerted (at least in part) at the level of transcription of the SLC5A6 gene and may involve epigenetic/molecular mechanisms.
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Affiliation(s)
- Padmanabhan Srinivasan
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Rubina Kapadia
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Arundhati Biswas
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
| | - Hamid M Said
- Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California; and Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California
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Xue J, Zempleni J. Epigenetic synergies between biotin and folate in the regulation of pro-inflammatory cytokines and repeats. Scand J Immunol 2014; 78:419-25. [PMID: 24007195 DOI: 10.1111/sji.12108] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 08/30/2013] [Indexed: 12/29/2022]
Abstract
The protein biotin ligase, holocarboxylase synthetase (HLCS), is a chromatin protein that interacts physically with the DNA methyltransferase DNMT1, the methylated cytosine-binding protein MeCP2 and the histone H3 K9-methyltransferase EHMT1, all of which participate in folate-dependent gene repression. Here we tested the hypothesis that biotin and folate synergize in the repression of pro-inflammatory cytokines and long-terminal repeats (LTRs), mediated by interactions between HLCS and other chromatin proteins. Biotin and folate supplementation could compensate for each other's deficiency in the repression of LTRs in Jurkat and U937 cells. For example, when biotin-deficient Jurkat cells were supplemented with folate, the expression of LTRs decreased by >70%. Epigenetic synergies were more complex in the regulation of cytokines compared with LTRs. For example, the abundance of TNF-α was 100% greater in folate- and biotin-supplemented U937 cells compared with biotin-deficient and folate-supplemented cells. The NF-κB inhibitor curcumin abrogated the effects of folate and biotin in cytokine regulation, suggesting that transcription factor signalling adds an extra layer of complexity to the regulation of cytokine genes by epigenetic phenomena. We conclude that biotin and folate synergize in the repression of LTRs and that these interactions are probably mediated by HLCS-dependent epigenetic mechanisms. In contrast, synergies between biotin and folate in the regulation of cytokines need to be interpreted in the context of transcription factor signalling.
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Affiliation(s)
- J Xue
- Department of Nutrition and Health Sciences, University of Nebraska at Lincoln, Lincoln, NE, USA
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Nagai Y, Tanaka Y, Kuroishi T, Sato R, Endo Y, Sugawara S. Histamine reduces susceptibility to natural killer cells via down-regulation of NKG2D ligands on human monocytic leukaemia THP-1 cells. Immunology 2012; 136:103-14. [PMID: 22304689 DOI: 10.1111/j.1365-2567.2012.03565.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Natural killer (NK) group 2D (NKG2D) is a key activating receptor expressed on NK cells, whose interaction with ligands on target cells plays an important role in tumorigenesis. However, the effect of histamine on NKG2D ligands on tumour cells is unclear. Here we showed that human monocytic leukaemia THP-1 cells constitutively express MHC class I-related chain A (MICA) and UL16-binding protein 1 on their surface, and incubation with histamine reduced the expression in a dose-dependent and time-dependent manner as assessed by flow cytometry. Interferon-γ augmented the surface expression of the NKG2D ligands, and this augmentation was significantly attenuated by histamine. The histamine H1 receptor (H1R) agonist 2-pyridylethylamine and H2R agonist dimaprit down-regulated the expression of NKG2D ligands, and activation of H1R and H2R signalling by A23187 and forskolin, respectively, had the same effect, indicating that the histamine-induced down-regulation of NKG2D ligands is mediated by H1R and H2R. Quantitative reverse transcription-PCR showed that mRNA levels of the NKG2D ligands and relevant microRNAs were not significantly changed by histamine. Histamine down-regulated the surface expression of endoplasmic reticulum protein 5, and inhibition of matrix metalloproteinases did not impair this down-regulation, indicating that proteolytic shedding was not involved. Instead, pharmacological inhibition of protein transport and proteasome abrogated it, and histamine enhanced ubiquitination of MICA. Furthermore, histamine treatment significantly reduced susceptibility to NK cell-mediated cytotoxicity. These results suggest that histamine down-regulates NKG2D ligands through the activation of an H1R- and H2R-mediated ubiquitin-proteasome pathway and consequently reduces susceptibility to NK cells.
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Affiliation(s)
- Yasuhiro Nagai
- Division of Oral Immunology, Department of Oral Biology Division of Oral Surgery, Tohoku University Graduate School of Dentistry, Sendai, Japan
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Abstract
Systemic contact dermatitis is an inflammatory skin disease that may occur in persons with contact allergy when they are exposed to the hapten orally, transcutaneously, per rectum, intravesically, intravenously, or by inhalation. The most common causes of systemic contact dermatitis are drugs used both topically and systemically. Other causes are ubiquitously occurring haptens, such as the metals nickel, cobalt, gold, and chromate, and aromatic substances such as spices. Avoidance of the offending hapten is the most obvious treatment. For some haptens, such as nickel, diet treatment may be effective. Chelation therapy with disulfiram is another therapeutic option in nickel-allergic patients with systemic contact dermatitis. Hyposensitization therapy has been attempted with some success in systemic contact dermatitis caused by nickel and Parthenium hysterophorus.
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The elicitation step of nickel allergy is promoted in mice by microbe-related substances, including some from oral bacteria. Int Immunopharmacol 2011; 11:1916-24. [PMID: 21839857 DOI: 10.1016/j.intimp.2011.07.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 07/22/2011] [Accepted: 07/29/2011] [Indexed: 11/21/2022]
Abstract
Microbial components activate the host's innate immunity via interactions with molecules including TLRs and NODs. We previously reported that in mice (i) Escherichia coli lipopolysaccharide (LPS; TLR4 agonist) promotes Ni-allergy even in T-cell-deficient mice, (ii) E. coli LPS reduces the minimum allergy-inducing concentrations of Ni at both the sensitization and elicitation steps, and (iii) various microbe-related substances promote sensitization to Ni. Here, we examined the effects of microbe-related substances at the elicitation step. Mice (except for TLR4-mutated C3H/HeJ mice) were sensitized to Ni by intraperitoneal injection of NiCl(2) + E. coli LPS. Ten days later their ear-pinnas were challenged with 1 μM NiCl(2) with or without a test substance. Although NiCl(2) alone at this concentration does not induce Ni-allergy, its combination with the following substances induced Ni-allergy in BALB/c mice: LPS preparations from oral gram-negative bacteria (Prevotella intermedia and Porphyromonas gingivalis), a mannan preparation from a fungus (Saccharomyces cerevisiae), and synthetic NOD2 and TLR2 agonists. The effect of the mannan preparation was small in C3H/HeJ mice (sensitized with NiCl(2) + the P. intermedia preparation). The P. intermedia preparation promoted Ni-allergy in C3H/HeJ and nude mice, but not in mice deficient in either TLR2 or histidine decarboxylase. Intragingival injection of the P. intermedia preparation and later challenge with NiCl(2) alone to ear-pinnas also promoted Ni-allergy. These results indicate that (i) in Ni-allergy, a microbial milieu or innate immunity is important at the elicitation step, too, and (ii) some oral bacteria may promote Ni-allergy via TLR2-stimulant(s) production.
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Bao B, Rodriguez-Melendez R, Wijeratne SSK, Zempleni J. Biotin regulates the expression of holocarboxylase synthetase in the miR-539 pathway in HEK-293 cells. J Nutr 2010; 140:1546-51. [PMID: 20592104 PMCID: PMC2924595 DOI: 10.3945/jn.110.126359] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Holocarboxylase synthetase (HCS) catalyzes the covalent binding of biotin to carboxylases and histones. In mammals, the expression of HCS depends on biotin, but the mechanism of regulation is unknown. Here we tested the hypothesis that microRNA (miR) plays a role in the regulation of the HCS gene. Human embryonic kidney cells were used as the primary model, but cell lines from other tissues and primary human cells were also tested. In silico searches revealed an evolutionary conserved binding site for miR-539 in the 3 prime -untranslated region (3 prime -UTR) of HCS mRNA. Transgenic cells and reporter gene constructs were used to demonstrate that miR-539 decreases the expression of HCS at the level of transcription rather than translation; these findings were corroborated in nontransgenic cells. When miR-539 was overexpressed in transgenic cells, the abundance of both HCS and biotinylated histones decreased. The abundance of miR-539 was tissue dependent: fibroblasts gt kidney cells gt intestinal cells gt lymphoid cells. Dose-response studies revealed that the abundance of miR-539 was significantly higher at physiological concentrations of biotin than both biotin-deficient and biotin-supplemented media in all cell lines tested. In kidney cells, the expression of HCS was lower in cells in physiological medium than in deficient and supplemented medium. In contrast, in fibroblasts, lymphoid cells, and intestinal cells, there was no apparent link between miR-539 abundance and HCS expression, suggesting that factors other than miR-539 also contribute to the regulation of HCS expression in some tissues. Collectively, the results of this study suggest that miR-539 is among the factors sensing biotin and regulating HCS.
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