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Wang Y, Hong J, Liu X, Yang H, Liu R, Wu J, Wang A, Lin D, Lai R. Snake cathelicidin from Bungarus fasciatus is a potent peptide antibiotics. PLoS One 2008; 3:e3217. [PMID: 18795096 PMCID: PMC2528936 DOI: 10.1371/journal.pone.0003217] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 08/25/2008] [Indexed: 12/21/2022] Open
Abstract
Background Cathelicidins are a family of antimicrobial peptides acting as multifunctional effector molecules of innate immunity, which are firstly found in mammalians. Recently, several cathelicidins have also been found from chickens and fishes. No cathelicidins from other non-mammalian vertebrates have been reported. Principal Findings In this work, a cathelicidin-like antimicrobial peptide named cathelicidin-BF has been purified from the snake venoms of Bungarus fasciatus and its cDNA sequence was cloned from the cDNA library, which confirm the presence of cathelicidin in reptiles. As other cathelicidins, the precursor of cathelicidin-BF has cathelin-like domain at the N terminus and carry the mature cathelicidin-BF at the C terminus, but it has an atypical acidic fragment insertion between the cathelin-like domain and the C-terminus. The acidic fragment is similar to acidic domains of amphibian antimicrobial precursors. Phylogenetic analysis revealed that the snake cathelicidin had the nearest evolution relationship with platypus cathelicidin. The secondary structure of cathelicidin-BF investigated by CD and NMR spectroscopy in the presence of the helicogenic solvent TFE is an amphipathic α-helical conformation as many other cathelicidins. The antimicrobial activities of cathelicidin BF against forty strains of microorganisms were tested. Cathelicidin-BF efficiently killed bacteria and some fungal species including clinically isolated drug-resistance microorganisms. It was especially active against Gram-negative bacteria. Furthermore, it could exert antimicrobial activity against some saprophytic fungus. No hemolytic and cytotoxic activity was observed at the dose of up to 400 µg/ml. Cathelicidin-BF could exist stably in the mice plasma for at least 2.5 hours. Conclusion Discovery of snake cathelicidin with atypical structural and functional characterization offers new insights on the evolution of cathelicidins. Potent, broad spectrum, salt-independent antimicrobial activities make cathelicidin-BF an excellent candidate for clinical or agricultural antibiotics.
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Affiliation(s)
- Yipeng Wang
- Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Jing Hong
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Xiuhong Liu
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Life Sciences College of Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Hailong Yang
- Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Rui Liu
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Life Sciences College of Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Jing Wu
- Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Aili Wang
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Life Sciences College of Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Donghai Lin
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- * E-mail: (DL); (RL)
| | - Ren Lai
- Biotoxin Units of Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Life Sciences College of Nanjing Agricultural University, Nanjing, Jiangsu, China
- * E-mail: (DL); (RL)
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Increased susceptibility to Mycobacterium avium in hemochromatosis protein HFE-deficient mice. Infect Immun 2008; 76:4713-9. [PMID: 18694968 DOI: 10.1128/iai.00612-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Mycobacterium avium is an opportunistic infectious agent in immunocompromised patients, living inside macrophage phagosomes. As for other mycobacterial species, iron availability is a critical factor for M. avium survival and multiplication. Indeed, an association between host secondary iron overload and increased susceptibility to these mycobacteria is generally acknowledged. However, studies on the impact of primary iron overload on M. avium infection have not been performed. In this work, we used animal models of primary iron overload that mimic the human disease hereditary hemochromatosis. This pathology is characterized by increased serum transferrin saturation with iron deposition in parenchymal cells, mainly in the liver, and is most often associated with mutations in the gene encoding the molecule HFE. In this paper, we demonstrate that mice of two genetically determined primary iron overload phenotypes, Hfe(-/-) and beta2m(-/-), show an increased susceptibility to experimental infection with M. avium and that during infection these animals accumulate iron inside granuloma macrophages. beta2m(-/-) mice were found to be more susceptible than Hfe(-/-) mice, but depleting Hfe(-/-) mice of CD8(+) cells had no effect on resistance to infection. Overall, our results suggest that serum iron, rather than total liver iron, levels have a considerable impact on susceptibility to M. avium infection.
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Browne SA, Reddan D. Potential role of bone morphogenetic protein (BMP) signalling as a potential therapeutic target for modification of iron balance. Nephrol Dial Transplant 2008; 24:28-30. [DOI: 10.1093/ndt/gfn551] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Wang Q, Du F, Qian ZM, Ge XH, Zhu L, Yung WH, Yang L, Ke Y. Lipopolysaccharide induces a significant increase in expression of iron regulatory hormone hepcidin in the cortex and substantia nigra in rat brain. Endocrinology 2008; 149:3920-5. [PMID: 18450970 PMCID: PMC2488231 DOI: 10.1210/en.2007-1626] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hepcidin plays an essential role in maintaining normal iron homeostasis outside the brain. This recently discovered iron regulation hormone is predominantly expressed in the liver, and regulated by iron and hypoxia. As an antimicrobial peptide, this hormone is also elevated during infections and inflammation. In this study we investigated the expression of hepcidin mRNA and protein in different brain regions, including the cortex, hippocampus, striatum, and substantia nigra, and the effects of lipopolysaccharide (LPS) on the expression of hepcidin using quantitative real-time RT-PCR and immunofluorescence analysis. Our data provided further evidence for the existence of hepcidin in all the regions we examined. We also demonstrated for the first time that LPS administration by iv injection can regulate the expression of hepcidin mRNA and protein not only in peripheral organs such as the liver, but also in the brain. LPS induced a significant increase in the expression of hepcidin mRNA and protein in the cortex and substantia nigra, but not in the hippocampus and striatum, indicating a regionally specific regulation of LPS on hepcidin in the brain. The relevant mechanisms and the functions of hepcidin in the brain remain to be elucidated.
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Affiliation(s)
- Qin Wang
- Laboratory of Brain Iron Metabolism, Department of Applied Biology & Chemical Technology, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
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55
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Gagliardo B, Faye A, Jaouen M, Deschemin JC, Canonne-Hergaux F, Vaulont S, Sari MA. Production of biologically active forms of recombinant hepcidin, the iron-regulatory hormone. FEBS J 2008; 275:3793-803. [PMID: 18557934 DOI: 10.1111/j.1742-4658.2008.06525.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Hepcidin is a liver produced cysteine-rich peptide hormone that acts as the central regulator of body iron metabolism. Hepcidin is synthesized under the form of a precursor, prohepcidin, which is processed to produce the biologically active mature 25 amino acid peptide. This peptide is secreted and acts by controlling the concentration of the membrane iron exporter ferroportin on intestinal enterocytes and macrophages. Hepcidin binds to ferroportin, inducing its internalization and degradation, thus regulating the export of iron from cells to plasma. The aim of the present study was to develop a novel method to produce human and mouse recombinant hepcidins, and to compare their biological activity towards their natural receptor ferroportin. Hepcidins were expressed in Escherichia coli as thioredoxin fusion proteins. The corresponding peptides, purified after cleavage from thioredoxin, were properly folded and contained the expected four-disulfide bridges without the need of any renaturation or oxidation steps. Human and mouse hepcidins were found to be biologically active, promoting ferroportin degradation in macrophages. Importantly, biologically inactive aggregated forms of hepcidin were observed depending on purification and storage conditions, but such forms were unrelated to disulfide bridge formation.
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57
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Collins JF, Hu Z, Ranganathan PN, Feng D, Garrick LM, Garrick MD, Browne RW. Induction of arachidonate 12-lipoxygenase (Alox15) in intestine of iron-deficient rats correlates with the production of biologically active lipid mediators. Am J Physiol Gastrointest Liver Physiol 2008; 294:G948-62. [PMID: 18258795 DOI: 10.1152/ajpgi.00274.2007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To identify novel genes associated with iron metabolism, we performed gene chip studies in two models of iron deficiency: iron-deprived rats and rats deficient in the principal intestinal iron transporter, divalent metal transporter 1 (i.e., Belgrade rats). Affymetrix rat genome gene chips were utilized (RAE230) with cRNA samples derived from duodenum and jejunum of experimental and control animals. Computational analysis and statistical data reduction identified 29 candidate genes, which were induced in both models of iron deficiency. Gene ontology analysis showed enrichment for genes related to lipid homeostasis, and one gene related to this physiological process, a leukocyte type, arachidonate 12-lipoxygenase (Alox15), was selected for further examination. TaqMan real-time PCR studies demonstrated strong induction of Alox15 throughout the small and large intestine, and in the liver of iron-deficient rats. Polyclonal antibodies were developed and utilized to demonstrate that proteins levels are significantly increased in the intestinal epithelium of iron-deprived rats. HPLC analysis revealed altered intestinal lipid metabolism indicative of Alox15 activity, which resulted in the production of biologically active lipid molecules (12-HETE, 13-HODE, and 13-HOTE). The overall effect is a perturbation of intestinal lipid homeostasis, which results in the production of lipids essentially absent in the intestine of control rats. We have thus provided mechanistic insight into the alteration in lipid metabolism that occurs during iron deficiency, in that induction of Alox15 mRNA expression may be the primary event. The resulting lipid mediators may be related to documented alterations in villus structure and cell proliferation rates in iron deficiency, or to structural alterations in membrane lipid composition.
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Affiliation(s)
- James F Collins
- Dept. of Exercise and Nutrition Sciences, G10 Farber Hall, 3435 Main St., Univ. at Buffalo, Buffalo, NY 14214, USA.
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Mena NP, Esparza A, Tapia V, Valdés P, Núñez MT. Hepcidin inhibits apical iron uptake in intestinal cells. Am J Physiol Gastrointest Liver Physiol 2008; 294:G192-8. [PMID: 17962361 DOI: 10.1152/ajpgi.00122.2007] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepcidin (Hepc) is considered a key mediator in iron trafficking. Although the mechanism of Hepc action in macrophages is fairly well established, much less is known about its action in intestinal cells, one of the main targets of Hepc. The current study investigated the effects of physiologically generated Hepc on iron transport in Caco-2 cell monolayers and rat duodenal segments compared with the effects on the J774 macrophage cell line. Addition of Hepc to Caco-2 cells or rat duodenal segments strongly inhibited apical (55)Fe uptake without apparent effects on the transfer of (55)Fe from the cells to the basolateral medium. Concurrently, the levels of divalent metal transporter 1 (DMT1) mRNA and protein in Caco-2 cells decreased while the mRNA and protein levels of the iron export transporter ferroportin did not change. Plasma membrane localization of ferroportin was studied by selective biotinylation of apical and basolateral membrane domains; Hepc induced rapid internalization of ferroportin in J774 cells but not in Caco-2 cells These results indicate that the effect of Hepc is cell dependent: in macrophages it inhibits iron export by inducing ferroportin degradation, whereas in enterocytes it inhibits apical iron uptake by inhibiting DMT1 transcription. Our results highlight the crucial role of Hepc in the control of intestinal iron absorption.
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Affiliation(s)
- Natalia P Mena
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
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59
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Casley WL, Ogrodowczyk C, Larocque L, Jaentschke B, LeBlanc-Westwood C, Menzies JA, Whitehouse L, Hefford MA, Aubin RA, Thorn CF, Whitehead AS, Li X. Cytotoxic doses of ketoconazole affect expression of a subset of hepatic genes. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2007; 70:1946-1955. [PMID: 17966066 DOI: 10.1080/15287390701551407] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Ketoconazole is a widely prescribed antifungal drug, which has also been investigated as an anticancer therapy in both clinical and pre-clinical settings. However, severe hepatic injuries were reported to be associated with the use of ketoconazole, even in patients routinely monitored for their liver functions. Several questions concerning ketoconazole-induced hepatic injury remain unanswered, including (1) does ketoconazole alter cytochrome P450 expression at the transcriptional level?, (2) what types of gene products responsible for cytotoxicity are induced by ketoconazole?, and (3) what role do the major metabolites of ketoconazole play in this pathophysiologic process? A mouse model was employed to investigate hepatic gene expression following hepatotoxic doses of ketoconazole. Hepatic gene expression was analyzed using a toxicogenomic microarray platform, which is comprised of cDNA probes generated from livers exposed to various hepatoxicants. These hepatoxicants fall into five well-studied toxicological categories: peroxisome proliferators, aryl hydrocarbon receptor agonists, noncoplanar polychlorinated biphenyls, inflammatory agents, and hypoxia-inducing agents. Nine genes encoding enzymes involved in Phase I metabolism and one Phase II enzyme (glutathione S-transferase) were found to be upregulated. Serum amyloid A (SAA1/2) and hepcidin were the only genes that were downregulated among the 2364 genes assessed. In vitro cytotoxicity and transcription analyses revealed that SAA and hepcidin are associated with the general toxicity of ketoconazole, and might be usefully explored as generalized surrogate markers of xenobiotic-induced hepatic injury. Finally, it was shown that the primary metabolite of ketoconazole (de-N-acetyl ketoconazole) is largely responsible for the hepatoxicity and the downregulation of SAA and hepcidin.
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Affiliation(s)
- William L Casley
- Center for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, Ottawa, Ontario, Canada
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60
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Ibrahim AS, Gebermariam T, Fu Y, Lin L, Husseiny MI, French SW, Schwartz J, Skory CD, Edwards JE, Spellberg BJ. The iron chelator deferasirox protects mice from mucormycosis through iron starvation. J Clin Invest 2007; 117:2649-57. [PMID: 17786247 PMCID: PMC1957543 DOI: 10.1172/jci32338] [Citation(s) in RCA: 229] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 06/13/2007] [Indexed: 01/19/2023] Open
Abstract
Mucormycosis causes mortality in at least 50% of cases despite current first-line therapies. Clinical and animal data indicate that the presence of elevated available serum iron predisposes the host to mucormycosis. Here we demonstrate that deferasirox, an iron chelator recently approved for use in humans by the US FDA, is a highly effective treatment for mucormycosis. Deferasirox effectively chelated iron from Rhizopus oryzae and demonstrated cidal activity in vitro against 28 of 29 clinical isolates of Mucorales at concentrations well below clinically achievable serum levels. When administered to diabetic ketoacidotic or neutropenic mice with mucormycosis, deferasirox significantly improved survival and decreased tissue fungal burden, with an efficacy similar to that of liposomal amphotericin B. Deferasirox treatment also enhanced the host inflammatory response to mucormycosis. Most importantly, deferasirox synergistically improved survival and reduced tissue fungal burden when combined with liposomal amphotericin B. These data support clinical investigation of adjunctive deferasirox therapy to improve the poor outcomes of mucormycosis with current therapy. As iron availability is integral to the pathogenesis of other infections (e.g., tuberculosis, malaria), broader investigation of deferasirox as an antiinfective treatment is warranted.
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Affiliation(s)
- Ashraf S Ibrahim
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90502, USA.
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Abstract
Progress in the characterization of genes involved in the control of iron homeostasis in humans and in mice has improved the definition of iron overload and of the cells affected by it. The cell involved in iron overload with the greatest effect on immunity is the macrophage. Intriguing evidence has emerged, however, in the last 12 years indicating that parenchymal iron overload is linked to genes classically associated with the immune system. This review offers an update of the genes and proteins relevant to iron metabolism expressed in cells of the innate immune system, and addresses the question of how this system is affected in clinical situations of iron overload. The relationship between iron and the major cells of adaptive immunity, the T lymphocytes, will also be reviewed. Most studies addressing this last question in humans were performed in the clinical model of Hereditary Hemochromatosis. Data will also be reviewed demonstrating how the disruption of molecules essentially involved in adaptive immune responses result in the spontaneous development of iron overload and how they act as modifiers of iron overload.
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Affiliation(s)
- Graça Porto
- Institute of Molecular and Cellular Biology, Rua do Campo Alegre, Porto 8234150, Portugal.
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Kohgo Y, Ikuta K, Ohtake T, Torimoto Y, Kato J. Iron overload and cofactors with special reference to alcohol, hepatitis C virus infection and steatosis/insulin resistance. World J Gastroenterol 2007; 13:4699-706. [PMID: 17729391 PMCID: PMC4611191 DOI: 10.3748/wjg.v13.i35.4699] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
There are several cofactors which affect body iron metabolism and accelerate iron overload. Alcohol and hepatic viral infections are the most typical examples for clarifying the role of cofactors in iron overload. In these conditions, iron is deposited in hepatocytes and Kupffer cells and reactive oxygen species (ROS) produced through Fenton reaction have key role to facilitate cellular uptake of transferrin-bound iron. Furthermore, hepcidin, antimicrobial peptide produced mainly in the liver is also responsible for intestinal iron absorption and reticuloendothelial iron release. In patients with ceruloplasmin deficiency, anemia and secondary iron overload in liver and neurodegeneration are reported. Furthermore, there is accumulating evidence that fatty acid accumulation without alcohol and obesity itself modifies iron overload states. Ineffective erythropoiesis is also an important factor to accelerate iron overload, which is associated with diseases such as thalassemia and myelodysplastic syndrome. When this condition persists, the dietary iron absorption is increased due to the increment of bone marrow erythropoiesis and tissue iron overload will thereafter occurs. In porphyria cutanea tarda, iron is secondarily accumulated in the liver.
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Affiliation(s)
- Yutaka Kohgo
- Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical College, Midorigaoka-higashi 2-1, Asahikawa 078-8510, Japan.
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Schmitz G, Grandl M. Role of redox regulation and lipid rafts in macrophages during Ox-LDL-mediated foam cell formation. Antioxid Redox Signal 2007; 9:1499-518. [PMID: 17600463 DOI: 10.1089/ars.2007.1663] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hyperlipidemias and small dense LDLs in patients with high-triglyceride low-HDL syndromes lead to a prolonged half life of apoB-containing particles. This is associated with reactive oxygen species (ROS) activation and leads to formation of oxidized LDL (Ox-LDL). Generators of ROS in macrophages (MACs) include myeloperoxidase (MPO)-mediated respiratory burst and raft-associated NADPH-oxidase. The intracellular oxidant milieu is involved in cellular signaling pathways, like ion-transport systems, protein phosphorylation, and gene expression. Lipid oxidation through ROS can amplify foam cell formation through Ox-LDL uptake, leading to formation of ceramide (Cer)-rich lipid membrane microdomains, and is associated with expansion of the lysosomal compartment and an upregulation of ABCA1 and other genes of the AP3 secretory pathway. Ox-LDL may also affect cell-surface turnover of Cer-backbone sphingolipids and apoE-mediated uptake by LRP-family members. In contrast, HDL-mediated lipid efflux causes disruption of lipid membrane microdomains and prevents foam cell formation. Oxidation of HDL through MPO leads to a failure of lipid efflux and enhancement of MAC loading. Therefore, lipid rafts and oxidation processes are important in regulation of MAC foam cell formation and atherosclerosis, and the balance between oxidant and antioxidant intracellular systems is critically important for efficient MAC function.
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Affiliation(s)
- Gerd Schmitz
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany.
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Caramelo C, Justo S, Gil P. Anemia en la insuficiencia cardiaca: fisiopatología, patogenia, tratamiento e incógnitas. Rev Esp Cardiol 2007. [DOI: 10.1157/13108999] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Gardenghi S, Marongiu MF, Ramos P, Guy E, Breda L, Chadburn A, Liu Y, Amariglio N, Rechavi G, Rachmilewitz EA, Breuer W, Cabantchik ZI, Wrighting DM, Andrews NC, de Sousa M, Giardina PJ, Grady RW, Rivella S. Ineffective erythropoiesis in beta-thalassemia is characterized by increased iron absorption mediated by down-regulation of hepcidin and up-regulation of ferroportin. Blood 2007; 109:5027-35. [PMID: 17299088 PMCID: PMC1885515 DOI: 10.1182/blood-2006-09-048868] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Progressive iron overload is the most salient and ultimately fatal complication of beta-thalassemia. However, little is known about the relationship among ineffective erythropoiesis (IE), the role of iron-regulatory genes, and tissue iron distribution in beta-thalassemia. We analyzed tissue iron content and iron-regulatory gene expression in the liver, duodenum, spleen, bone marrow, kidney, and heart of mice up to 1 year old that exhibit levels of iron overload and anemia consistent with both beta-thalassemia intermedia (th3/+) and major (th3/th3). Here we show, for the first time, that tissue and cellular iron distribution are abnormal and different in th3/+ and th3/th3 mice, and that transfusion therapy can rescue mice affected by beta-thalassemia major and modify both the absorption and distribution of iron. Our study reveals that the degree of IE dictates tissue iron distribution and that IE and iron content regulate hepcidin (Hamp1) and other iron-regulatory genes such as Hfe and Cebpa. In young th3/+ and th3/th3 mice, low Hamp1 levels are responsible for increased iron absorption. However, in 1-year-old th3/+ animals, Hamp1 levels rise and it is rather the increase of ferroportin (Fpn1) that sustains iron accumulation, thus revealing a fundamental role of this iron transporter in the iron overload of beta-thalassemia.
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Affiliation(s)
- Sara Gardenghi
- Department of Pediatric Hematology-Oncology, Children's Blood Foundation Laboratories, Weill Medical College of Cornell University, 515E 71st Street S702, New York, NY 10021, USA
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