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Reza Sepand M, Bigdelou B, Salek Maghsoudi A, Sanadgol N, Ho JQ, Chauhan P, Raoufi M, Kermanian A, Esfandyarpour R, Javad Hajipour M, Zanganeh S. Ferroptosis: Environmental causes, biological redox signaling responses, cancer and other health consequences. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2023.215024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Ma X, Zhao J, Feng H. Targeting iron metabolism in osteosarcoma. Discov Oncol 2023; 14:31. [PMID: 36897430 PMCID: PMC10006389 DOI: 10.1007/s12672-023-00637-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 02/28/2023] [Indexed: 03/11/2023] Open
Abstract
Osteosarcoma (OS) is the most common primary solid malignant tumour of bone, with rapid progression and a very poor prognosis. Iron is an essential nutrient that makes it an important player in cellular activities due to its inherent ability to exchange electrons, and its metabolic abnormalities are associated with a variety of diseases. The body tightly regulates iron content at the systemic and cellular levels through various mechanisms to prevent iron deficiency and overload from damaging the body. OS cells regulate various mechanisms to increase the intracellular iron concentration to accelerate proliferation, and some studies have revealed the hidden link between iron metabolism and the occurrence and development of OS. This article briefly describes the process of normal iron metabolism, and focuses on the research progress of abnormal iron metabolism in OS from the systemic and cellular levels.
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Affiliation(s)
- Xiaowei Ma
- Department of Orthopedics, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 17 Nanli, Panjiayuan, Chaoyang District, Beijing, 100021, People's Republic of China
- Department of Orthopedics, The Fourth Hospital of Hebei Medical University, 12 Health Road, Hebei Province, Shijiazhuang, 050011, People's Republic of China
| | - Jiazheng Zhao
- Department of Orthopedics, The Fourth Hospital of Hebei Medical University, 12 Health Road, Hebei Province, Shijiazhuang, 050011, People's Republic of China
| | - Helin Feng
- Department of Orthopedics, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 17 Nanli, Panjiayuan, Chaoyang District, Beijing, 100021, People's Republic of China.
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Zhu L, Luo S, Zhu Y, Tang S, Li C, Jin X, Wu F, Jiang H, Wu L, Xu Y. The Emerging Role of Ferroptosis in Various Chronic Liver Diseases: Opportunity or Challenge. J Inflamm Res 2023; 16:381-389. [PMID: 36748023 PMCID: PMC9899014 DOI: 10.2147/jir.s385977] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/06/2023] [Indexed: 02/01/2023] Open
Abstract
Ferroptosis is a recently identified iron-dependent form of intracellular lipid peroxide accumulation-mediated cell death. Different from other types of cell death mechanisms, it exhibits distinct biological and morphological features characterized by the loss of lipid peroxidase repair activity caused by glutathione peroxidase 4, the presence of redox-active iron, and the oxidation of phospholipids-containing polyunsaturated fatty acids. In recent years, studies have shown that ferroptosis plays a key role in various liver diseases such as alcoholic liver injury, non-alcoholic steatohepatitis, liver cirrhosis, and liver cancer. However, the mechanism of ferroptosis and its regulation on chronic liver disease are controversial among different types of cells in the liver. Herein, we summarize the current studies on mechanism of ferroptosis in chronic liver disease, aiming to outline the blueprint of ferroptosis as an effective option for chronic liver disease therapy.
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Affiliation(s)
- Lujian Zhu
- Department of Infectious Diseases, Jinhua Municipal Central Hospital, Jinhua, People’s Republic of China
| | - Shengnan Luo
- Department of Infectious Diseases, Jinhua Municipal Central Hospital, Jinhua, People’s Republic of China
| | - Yin Zhu
- Department of Infectious Diseases, Taizhou Enze Medical Center (Group), Enze Hospital, Taizhou, People’s Republic of China
| | - Shiyue Tang
- Department of Infectious Diseases, Jinhua Municipal Central Hospital, Jinhua, People’s Republic of China
| | - Chenge Li
- College of Public Health and Management, Wenzhou Medical University, Wenzhou, People’s Republic of China
| | - Xiaozhi Jin
- Department of Infectious Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, People’s Republic of China
| | - Faling Wu
- Department of Infectious Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, People’s Republic of China
| | - Huimian Jiang
- Department of Infectious Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, People’s Republic of China
| | - Lina Wu
- Department of Infectious Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, People’s Republic of China
| | - Yejin Xu
- Department of Infectious Diseases, Jinhua Municipal Central Hospital, Jinhua, People’s Republic of China,Correspondence: Yejin Xu, Department of Infectious Diseases, Jinhua Municipal Central Hospital, Jinhua, People’s Republic of China, Email
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Ferroptosis as a mechanism of non-ferrous metal toxicity. Arch Toxicol 2022; 96:2391-2417. [PMID: 35727353 DOI: 10.1007/s00204-022-03317-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/11/2022] [Indexed: 11/02/2022]
Abstract
Ferroptosis is a recently discovered form of regulated cell death, implicated in multiple pathologies. Given that the toxicity elicited by some metals is linked to alterations in iron metabolism and induction of oxidative stress and lipid peroxidation, ferroptosis might be involved in such toxicity. Although direct evidence is insufficient, certain pioneering studies have demonstrated a crosstalk between metal toxicity and ferroptosis. Specifically, the mechanisms underlying metal-induced ferroptosis include induction of ferritinophagy, increased DMT-1 and TfR cellular iron uptake, mitochondrial dysfunction and mitochondrial reactive oxygen species (mitoROS) generation, inhibition of Xc-system and glutathione peroxidase 4 (GPX4) activity, altogether resulting in oxidative stress and lipid peroxidation. In addition, there is direct evidence of the role of ferroptosis in the toxicity of arsenic, cadmium, zinc, manganese, copper, and aluminum exposure. In contrast, findings on the impact of cobalt and nickel on ferroptosis are scant and nearly lacking altogether for mercury and especially lead. Other gaps in the field include limited studies on the role of metal speciation in ferroptosis and the critical cellular targets. Although further detailed studies are required, it seems reasonable to propose even at this early stage that ferroptosis may play a significant role in metal toxicity, and its modulation may be considered as a potential therapeutic tool for the amelioration of metal toxicity.
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Zhang Z, Costa M. p62 functions as a signal hub in metal carcinogenesis. Semin Cancer Biol 2021; 76:267-278. [PMID: 33894381 DOI: 10.1016/j.semcancer.2021.04.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 04/06/2021] [Accepted: 04/15/2021] [Indexed: 12/13/2022]
Abstract
A number of metals are toxic and carcinogenic to humans. Reactive oxygen species (ROS) play an important role in metal carcinogenesis. Oxidative stress acts as the converging point among various stressors with ROS being the main intracellular signal transducer. In metal-transformed cells, persistent expression of p62 and erythroid 2-related factor 2 (Nrf2) result in apoptosis resistance, angiogenesis, inflammatory microenvironment, and metabolic reprogramming, contributing to overall mechanism of metal carcinogenesis. Autophagy, a conserved intracellular process, maintains cellular homeostasis by facilitating the turnover of protein aggregates, cellular debris, and damaged organelles. In addition to being a substrate of autophagy, p62 is also a crucial molecule in a myriad of cellular functions and in molecular events, which include oxidative stress, inflammation, apoptosis, cell proliferation, metabolic reprogramming, that modulate cell survival and tumor growth. The multiple functions of p62 are appreciated by its ability to interact with several key components involved in various oncogenic pathways. This review summarizes the current knowledge and progress in studies of p62 and metal carcinogenesis with emphasis on oncogenic pathways related to oxidative stress, inflammation, apoptosis, and metabolic reprogramming.
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Affiliation(s)
- Zhuo Zhang
- Department of Environmental Medicine, NYU School of Medicine, 341 East 25th Street, New York, NY 10010, USA
| | - Max Costa
- Department of Environmental Medicine, NYU School of Medicine, 341 East 25th Street, New York, NY 10010, USA.
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Ghio AJ, Soukup JM, Dailey LA, Madden MC. Air pollutants disrupt iron homeostasis to impact oxidant generation, biological effects, and tissue injury. Free Radic Biol Med 2020; 151:38-55. [PMID: 32092410 PMCID: PMC8274387 DOI: 10.1016/j.freeradbiomed.2020.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/27/2020] [Accepted: 02/10/2020] [Indexed: 02/07/2023]
Abstract
Air pollutants cause changes in iron homeostasis through: 1) a capacity of the pollutant, or a metabolite(s), to complex/chelate iron from pivotal sites in the cell or 2) an ability of the pollutant to displace iron from pivotal sites in the cell. Through either pathway of disruption in iron homeostasis, metal previously employed in essential cell processes is sequestered after air pollutant exposure. An absolute or functional cell iron deficiency results. If enough iron is lost or is otherwise not available within the cell, cell death ensues. However, prior to death, exposed cells will attempt to reverse the loss of requisite metal. This response of the cell includes increased expression of metal importers (e.g. divalent metal transporter 1). Oxidant generation after exposure to air pollutants includes superoxide production which functions in ferrireduction necessary for cell iron import. Activation of kinases and phosphatases and transcription factors and increased release of pro-inflammatory mediators also result from a cell iron deficiency, absolute or functional, after exposure to air pollutants. Finally, air pollutant exposure culminates in the development of inflammation and fibrosis which is a tissue response to the iron deficiency challenging cell survival. Following the response of increased expression of importers and ferrireduction, activation of kinases and phosphatases and transcription factors, release of pro-inflammatory mediators, and inflammation and fibrosis, cell iron is altered, and a new metal homeostasis is established. This new metal homeostasis includes increased total iron concentrations in cells with metal now at levels sufficient to meet requirements for continued function.
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Affiliation(s)
- Andrew J Ghio
- From the National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA.
| | - Joleen M Soukup
- From the National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA
| | - Lisa A Dailey
- From the National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA
| | - Michael C Madden
- From the National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA
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Huang BW, Ray PD, Iwasaki K, Tsuji Y. Transcriptional regulation of the human ferritin gene by coordinated regulation of Nrf2 and protein arginine methyltransferases PRMT1 and PRMT4. FASEB J 2013; 27:3763-74. [PMID: 23699174 DOI: 10.1096/fj.12-226043] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Antioxidant genes such as ferritin are transcriptionally activated in oxidative stress via the antioxidant responsive element (ARE), to which nuclear factor-E2-related factor 2 (Nrf2) binds and activates transcription. Histone modification plays a cooperative and essential role in transcriptional regulation; however, its role in antioxidant gene transcription remains elusive. Arsenic exposure activated ferritin transcription via the ARE concomitant with increased methylation of histones H4Arg3 (H4R3) and H3Arg17 (H3R17). To test our hypothesis that histone H4R3 and H3R17 methylation regulates ferritin transcription, H4R3 and H3R17 protein arginine (R) methyltransferases 1 and 4 (PRMT1 and PRMT4) were investigated. Arsenic exposure of human HaCaT keratinocytes induced nuclear accumulation of PRMT1 and PRMT4, histone H4R3 and H3R17 methylation proximal to the ARE, but not to the non-ARE regions of ferritin genes. PRMT1 or PRMT4 knockdown did not block Nrf2 nuclear accumulation but inhibited Nrf2 binding to the AREs by ∼40% (P<0.05), thus diminishing ferritin transcription in HaCaT and human primary keratinocytes and fibroblasts, causing enhanced cellular susceptibility to arsenic toxicity as evidenced by 2-fold caspase 3 activation. Focused microarray further characterized several oxidative stress response genes are subject to PRMT1 or PRMT4 regulation. Collectively, PRMT1 and PRMT4 regulate the ARE and cellular antioxidant response to arsenic.
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Affiliation(s)
- Bo-Wen Huang
- Department of Environmental and Molecular Toxicology, North Carolina State University, Campus Box 7633, Raleigh, NC 27695, USA
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Wu J, Sowinska A, Huang X, Klein CB, Pelle E, Frenkel K. Impairment of antioxidant defenses as a contributor to arsenite-induced cell transformation. Biometals 2012; 25:927-37. [PMID: 22692362 DOI: 10.1007/s10534-012-9559-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 05/11/2012] [Indexed: 11/26/2022]
Abstract
Arsenite (As) causes transformation of human osteogenic sarcoma cells (HOS) when applied continuously at low doses (0.1-0.5 μM) during 8-weeks of exposure. However, the mechanisms by which As transforms human cells are not known. We investigated whether alterations occurred in gene expression and protein levels of antioxidant defense proteins, such as superoxide dismutase 1 (SOD1) and ferritin. In comparison to control HOS cells, 0.1 μM As induced greater cell proliferation and decreased anti-oxidant defenses. The tumor suppressor protein p53 was also decreased at both mRNA and protein levels. Further, pig3 (p53-induced-gene 3), a homolog of NQO1 (NADPH quinone oxidoreductase 1), was also down-regulated after 8 weeks of As challenge. The treatment of HOS cells with dicumarol, a NQO1 inhibitor, caused a dose-dependent decline in p53 protein levels, proving the effect of an antioxidant enzyme on p53 expression and, potentially, down-stream processes. Caffeic acid phenethyl ester, an antioxidant, prevented the As-induced decreases in SOD1, p53, and ferritin mRNA and protein levels. SOD1, p53 and ferritin levels were inversely related to As-induced cell proliferation. Cumulatively, these results strongly suggest that impairment in antioxidant defenses contributes to As-induced human cell transformation and that the p53 pathway is involved in the process.
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Affiliation(s)
- Jing Wu
- Department of Environmental Medicine, New York University School of Medicine, New York, NY 10016, USA.
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The neglected significance of "antioxidative stress". OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:480895. [PMID: 22655114 PMCID: PMC3357598 DOI: 10.1155/2012/480895] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 02/17/2012] [Indexed: 12/13/2022]
Abstract
Oxidative stress arises when there is a marked imbalance between the production and removal of reactive oxygen species (ROS) in favor of the prooxidant balance, leading to potential oxidative damage. ROSs were considered traditionally to be only a toxic byproduct of aerobic metabolism. However, recently, it has become apparent that ROS might control many different physiological processes such as induction of stress response, pathogen defense, and systemic signaling. Thus, the imbalance of the increased antioxidant potential, the so-called antioxidative stress, should be as dangerous as well. Here, we synthesize increasing evidence on “antioxidative stress-induced” beneficial versus harmful roles on health, disease, and aging processes. Oxidative stress is not necessarily an un-wanted situation, since its consequences may be beneficial for many physiological reactions in cells. On the other hand, there are potentially harmful effects of “antioxidative stress,” especially in the cases of overconsumption of synthetic antioxidants. Antioxidants can neutralize ROS and decrease oxidative stress; however, this is not always beneficial in regard to disease formation or progression (of, e.g., cancer) or for delaying aging.
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Eckard J, Dai J, Wu J, Jian J, Yang Q, Chen H, Costa M, Frenkel K, Huang X. Effects of cellular iron deficiency on the formation of vascular endothelial growth factor and angiogenesis. Iron deficiency and angiogenesis. Cancer Cell Int 2010; 10:28. [PMID: 20723262 PMCID: PMC2936284 DOI: 10.1186/1475-2867-10-28] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 08/19/2010] [Indexed: 11/10/2022] Open
Abstract
Background Young women diagnosed with breast cancer are known to have a higher mortality rate from the disease than older patients. Specific risk factors leading to this poorer outcome have not been identified. In the present study, we hypothesized that iron deficiency, a common ailment in young women, contributes to the poor outcome by promoting the hypoxia inducible factor-1α (HIF-1α and vascular endothelial growth factor (VEGF) formation. This hypothesis was tested in an in vitro cell culture model system. Results Human breast cancer MDA-MB-231 cells were transfected with transferrin receptor-1 (TfR1) shRNA to constitutively impair iron uptake. Cellular iron status was determined by a set of iron proteins and angiogenesis was evaluated by levels of VEGF in cells as well as by a mouse xenograft model. Significant decreases in ferritin with concomitant increases in VEGF were observed in TfR1 knockdown MDA-MB-231 cells when compared to the parental cells. TfR1 shRNA transfectants also evoked a stronger angiogenic response after the cells were injected subcutaneously into nude mice. The molecular mechanism appears that cellular iron deficiency elevates VEGF formation by stabilizing HIF-1α. This mechanism is also true in human breast cancer MCF-7 and liver cancer HepG2 cells. Conclusions Cellular iron deficiency increased HIF-1α, VEGF, and angiogenesis, suggesting that systemic iron deficiency might play an important part in the tumor angiogenesis and recurrence in this young age group of breast cancer patients.
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Affiliation(s)
- Jonathan Eckard
- Department of Environmental Medicine and New York University (NYU) Cancer Institute, NYU School of Medicine, New York, NY 10016, USA.
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Deng Z, Dailey LA, Soukup J, Stonehuerner J, Richards JD, Callaghan KD, Yang F, Ghio AJ. Zinc transport by respiratory epithelial cells and interaction with iron homeostasis. Biometals 2009; 22:803-15. [PMID: 19306086 DOI: 10.1007/s10534-009-9227-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 03/10/2009] [Indexed: 10/21/2022]
Abstract
Despite recurrent exposure to zinc through inhalation of ambient air pollution particles, relatively little information is known about the homeostasis of this metal in respiratory epithelial cells. We describe zinc uptake and release by respiratory epithelial cells and test the postulate that Zn(2+) transport interacts with iron homeostasis in these same cells. Zn(2+) uptake after 4 and 8 h of exposure to zinc sulfate was concentration- and time-dependent. A majority of Zn(2+) release occurred in the 4 h immediately following cell exposure to ZnSO(4). Regarding metal importers, mRNA for Zip1 and Zip2 showed no change after respiratory epithelial cell exposure to zinc while mRNA for divalent metal transporter (DMT)1 increased. Western blot assay for DMT1 protein supported an elevated expression of this transport protein following zinc exposure. RT-PCR confirmed mRNA for the metal exporters ZnT1 and ZnT4 with the former increasing after ZnSO(4). Cell concentrations of ferritin increased with zinc exposure while oxidative stress, measured as lipid peroxides, was decreased supporting an anti-oxidant function for Zn(2+). Increased DMT1 expression, following pre-incubations of respiratory epithelial cells with TNF-alpha, IFN-gamma, and endotoxin, was associated with significantly decreased intracellular zinc transport. Finally, incubations of respiratory epithelial cells with both zinc sulfate and ferric ammonium citrate resulted in elevated intracellular concentrations of both metals. We conclude that exposure to zinc increases iron uptake by respiratory epithelial cells. Elevations in cell iron can possibly affect an increased expression of DMT1 and ferritin which function to diminish oxidative stress. Comparable to other metal exposures, changes in iron homeostasis may contribute to the biological effects of zinc in specific cells and tissues.
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Affiliation(s)
- Zhongping Deng
- Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina, Chapel Hill, NC 27599-7310, USA
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Kell DB. Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases. BMC Med Genomics 2009; 2:2. [PMID: 19133145 PMCID: PMC2672098 DOI: 10.1186/1755-8794-2-2] [Citation(s) in RCA: 364] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Accepted: 01/08/2009] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. REVIEW We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here. CONCLUSION Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.
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Affiliation(s)
- Douglas B Kell
- School of Chemistry and Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.
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