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Ursini F, Maiorino M, Forman HJ. Redox homeostasis: The Golden Mean of healthy living. Redox Biol 2016; 8:205-15. [PMID: 26820564 PMCID: PMC4732014 DOI: 10.1016/j.redox.2016.01.010] [Citation(s) in RCA: 250] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 01/15/2016] [Accepted: 01/18/2016] [Indexed: 12/20/2022] Open
Abstract
The notion that electrophiles serve as messengers in cell signaling is now widely accepted. Nonetheless, major issues restrain acceptance of redox homeostasis and redox signaling as components of maintenance of a normal physiological steady state. The first is that redox signaling requires sudden switching on of oxidant production and bypassing of antioxidant mechanisms rather than a continuous process that, like other signaling mechanisms, can be smoothly turned up or down. The second is the misperception that reactions in redox signaling involve “reactive oxygen species” rather than reaction of specific electrophiles with specific protein thiolates. The third is that hormesis provides protection against oxidants by increasing cellular defense or repair mechanisms rather than by specifically addressing the offset of redox homeostasis. Instead, we propose that both oxidant and antioxidant signaling are main features of redox homeostasis. As the redox shift is rapidly reversed by feedback reactions, homeostasis is maintained by continuous signaling for production and elimination of electrophiles and nucleophiles. Redox homeostasis, which is the maintenance of nucleophilic tone, accounts for a healthy physiological steady state. Electrophiles and nucleophiles are not intrinsically harmful or protective, and redox homeostasis is an essential feature of both the response to challenges and subsequent feedback. While the balance between oxidants and nucleophiles is preserved in redox homeostasis, oxidative stress provokes the establishment of a new radically altered redox steady state. The popular belief that scavenging free radicals by antioxidants has a beneficial effect is wishful thinking. We propose, instead, that continuous feedback preserves nucleophilic tone and that this is supported by redox active nutritional phytochemicals. These nonessential compounds, by activating Nrf2, mimic the effect of endogenously produced electrophiles (parahormesis). In summary, while hormesis, although globally protective, results in setting up of a new phenotype, parahormesis contributes to health by favoring maintenance of homeostasis. Redox homeostasis is the continuously challenged oxidative/nucleophilic balance. Rheostatic redox signaling enzymes maintain oxidative/nucleophilic homeostasis. Phytochemicals assist redox homeostasis through oxidative feedback (parahormesis). Adaptation and hormesis while protective establish a new phenotype and set point.
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Affiliation(s)
- Fulvio Ursini
- Department of Molecular Medicine, University of Padova, Viale G. Colombo 3, I-35121 Padova, Italy
| | - Matilde Maiorino
- Department of Molecular Medicine, University of Padova, Viale G. Colombo 3, I-35121 Padova, Italy
| | - Henry Jay Forman
- Andrus Gerontology Center of the Davis School of Gerontology, University of Southern, California, 3715 McClintock Ave, Los Angeles, CA 90089-0191, USA
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2
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Rotoli BM, Dall'asta V, Barilli A, D'Ippolito R, Tipa A, Olivieri D, Gazzola GC, Bussolati O. Alveolar macrophages from normal subjects lack the NOS-related system y+ for arginine transport. Am J Respir Cell Mol Biol 2007; 37:105-12. [PMID: 17363779 DOI: 10.1165/rcmb.2006-0262oc] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Systems y+ and y+L represent the main routes for arginine transport in mammalian cells. While system y+ activity is needed for the stimulated NO production in rodent alveolar macrophages (AM), no information is yet available about arginine transport in human AM. We study here arginine influx and genes for arginine transporters in AM from bronchoalveolar lavage of normal subjects. These cells express the y+ -related genes SLC7A1/CAT1 and SLC7A2/CAT2B, as well as the y+L genes SLC7A7/y+LAT1 and SLC7A6/y+LAT2. However, compared with human endothelial cells, AM express much less SLC7A2 mRNA and higher levels of SLC7A7 mRNA. Granulocyte macrophage colony-stimulating factor or IFN-gamma do not change the expression of any transporter gene, while lipopolysaccharide induces SLC7A2/CAT2B. Under all the conditions tested, leucine inhibits most of the arginine transport in the presence of Na+ and N-ethylmaleimide, an inhibitor of system y+, is completely ineffective, indicating that system y+L operates most of the arginine influx. Comparable results are obtained in AM from patients with interstitial lung disease, such as Nonspecific Interstitial Pneumonia (NSIP), although these cells have a higher SLC7A1 and a lower SLC7A7 expression than AM from normal subjects. It is concluded that AM from normal subjects or patients with NSIP lack a functional transport system y+, a situation that may limit arginine availability for NO synthesis. Moreover, since mutations of SLC7A7/y+LAT1 cause Lysinuric Protein Intolerance, a disease often associated with AM impairment and alveolar proteinosis, the high SLC7A7 expression observed in human AM suggests that y+LAT1 activity is important for the function of these cells.
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Affiliation(s)
- Bianca Maria Rotoli
- Sezione di Patologia Generale e Clinica, Dipartimento di Medicina Sperimentale, Università di Parma, Via Volturno 39, 43100 Parma, Italy.
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3
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Bobola MS, Finn LS, Ellenbogen RG, Geyer JR, Berger MS, Braga JM, Meade EH, Gross ME, Silber JR. Apurinic/apyrimidinic endonuclease activity is associated with response to radiation and chemotherapy in medulloblastoma and primitive neuroectodermal tumors. Clin Cancer Res 2006; 11:7405-14. [PMID: 16243814 DOI: 10.1158/1078-0432.ccr-05-1068] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers resistance to radiation- and alkylator-induced cytotoxic abasic sites in human cells. We assayed apurinic/apyrimidinic endonuclease activity in medulloblastomas and primitive neuroectodermal tumors (PNET) to establish correlates with tumor and patient characteristics and with response to adjuvant radiation plus multiagent chemotherapy. EXPERIMENTAL DESIGN Ap endo activity was assayed in 52 medulloblastomas and 10 PNETs from patients 0.4 to 21 years old. Ape1/Ref-1, the predominant human Ap endo activity, was measured in 42 medulloblastomas by immunostaining. Cox proportional hazards regression models were used to analyze the association of activity with time to tumor progression (TTP). RESULTS Tumor Ap endo activity varied 180-fold and was significantly associated with age and gender. Tumor Ape1/Ref-1 was detected almost exclusively in nuclei. In a multivariate model, with Ap endo activity entered as a continuous variable, the hazard ratio for progression after adjuvant treatment in 46 medulloblastomas and four PNETs increased by a factor of 1.073 for every 0.01 unit increase in activity (P < or = 0.001) and was independent of age and gender. Suppressing Ap endo activity in a human medulloblastoma cell line significantly increased sensitivity to 1,3-bis(2-chlororethyl)-1-nitrosourea and temozolomide, suggesting that the association of tumor activity with TTP reflected, at least in part, abasic site repair. CONCLUSIONS Our data (a) suggest that Ap endo activity promotes resistance to radiation plus chemotherapy in medulloblastomas/PNETs, (b) provide a potential marker of treatment outcome, and (c) suggest clinical use of Ap endo inhibitors to overcome resistance.
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MESH Headings
- Adolescent
- Adult
- Antineoplastic Agents, Alkylating/pharmacology
- Blotting, Western
- Brain/drug effects
- Brain/enzymology
- Brain/radiation effects
- Brain Neoplasms/enzymology
- Brain Neoplasms/pathology
- Brain Neoplasms/therapy
- Carmustine/pharmacology
- Cell Line, Tumor
- Cell Nucleus/enzymology
- Cell Survival/drug effects
- Cell Survival/genetics
- Child
- Child, Preschool
- Combined Modality Therapy
- DNA-(Apurinic or Apyrimidinic Site) Lyase/genetics
- DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism
- Disease Progression
- Dose-Response Relationship, Drug
- Female
- Humans
- Immunohistochemistry
- Infant
- Infant, Newborn
- Male
- Medulloblastoma/enzymology
- Medulloblastoma/pathology
- Medulloblastoma/therapy
- Multivariate Analysis
- Neuroectodermal Tumors, Primitive/enzymology
- Neuroectodermal Tumors, Primitive/pathology
- Neuroectodermal Tumors, Primitive/therapy
- Oligonucleotides, Antisense/genetics
- RNA, Small Interfering/genetics
- Time Factors
- Transfection
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Affiliation(s)
- Michael S Bobola
- Division of Neurosurgery, Department of Surgery, Children's Hospital and Regional Medical Center, Seattle, WA 98105, USA.
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4
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Abstract
Human alveolar macrophages play a critical role in host defense and in the development of inflammation and fibrosis in the lung. Unlike their precursor cells, blood monocytes, alveolar macrophages are long-lived and tend to be resistant to apoptotic stimuli. In this study, we examined the role of differentiation in altering baseline phosphatidylinositol (PI) 3-kinase/Akt activity. We found that differentiation increased activity of pro-survival PI 3-kinase/Akt while decreasing amounts of the negative PI 3-kinase regulator, PTEN. PTEN is a lipid phosphatase with activity against phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3), the major bioactive product of PI 3-kinase. Examining in vivo differentiation of alveolar macrophages (by comparing blood monocytes to alveolar macrophages from single donors), we found that differentiation resulted in increased baseline reactive oxygen species (ROS) in the alveolar macrophages. This led to a deficiency in PTEN, increased activity of Akt, and prolonged survival of alveolar macrophages. These data support the hypothesis that alterations in ROS levels contribute to macrophage homeostasis by altering the balance between PI 3-kinase/Akt and the phosphatase, PTEN.
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Affiliation(s)
- Dawn M Flaherty
- Division of Pulmonary, Critical Care and Occupational Medicine, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242, USA.
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McEligot AJ, Yang S, Meyskens FL. REDOX REGULATION BY INTRINSIC SPECIES AND EXTRINSIC NUTRIENTS IN NORMAL AND CANCER CELLS. Annu Rev Nutr 2005; 25:261-95. [PMID: 16011468 DOI: 10.1146/annurev.nutr.25.050304.092633] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cells in multicellular organisms are exposed to both endogenous oxidative stresses generated metabolically and to oxidative stresses that originate from neighboring cells and from other tissues. To protect themselves from oxidative stress, cells are equipped with reducing buffer systems (glutathione/GSH and thioredoxin/thioredoxin reductase) and have developed several enzymatic mechanisms against oxidants that include catalase, superoxide dismutase, and glutathione peroxidase. Other major extrinsic defenses (from the diet) include ascorbic acid, beta-carotene and other carotenoids, and selenium. Recent evidence indicates that in addition to their antioxidant function, several of these redox species and systems are involved in regulation of biological processes, including cellular signaling, transcription factor activity, and apoptosis in normal and cancer cells. The survival and overall well-being of the cell is dependent upon the balance between the activity and the intracellular levels of these antioxidants as well as their interaction with various regulatory factors, including Ref-1, nuclear factor-kappaB, and activating protein-1.
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Affiliation(s)
- Archana Jaiswal McEligot
- Department of Medicine, Chao Family Comprehensive Cancer Center, University of California, Irvine, Orange, California 92868, USA.
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6
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Tell G, Damante G, Caldwell D, Kelley MR. The intracellular localization of APE1/Ref-1: more than a passive phenomenon? Antioxid Redox Signal 2005; 7:367-84. [PMID: 15706084 DOI: 10.1089/ars.2005.7.367] [Citation(s) in RCA: 298] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Human apurinic/apyrimidinic endonuclease 1/redox effector factor-1 (APE1/Ref-1) is a perfect paradigm of the functional complexity of a biological macromolecule. First, it plays a crucial role, by both redox-dependent and -independent mechanisms, as a transcriptional coactivator for different transcription factors, either ubiquitous (i.e., AP-1, Egr-1, NF-kappaB, p53, HIF) or tissue-specific (i.e., PEBP-2, Pax-5 and -8, TTF-1), in controlling different cellular processes such as apoptosis, proliferation, and differentiation. Second, it acts, as an apurinic/apyrimidinic endonuclease, during the second step of the DNA base excision repair pathway, which is responsible for the repair of cellular alkylation and oxidative DNA damages. Third, it controls the intracellular reactive oxygen species production by negatively regulating the activity of the Ras-related GTPase Rac1. Despite these known functions of APE1/Ref-1, information is still scanty about the molecular mechanisms responsible for the coordinated control of its several activities. Some evidence suggests that the expression and subcellular localization of APE1/Ref-1 are finely tuned. APE1/Ref-1 is a ubiquitous protein, but its expression pattern differs according to the different cell types. APE1/Ref-1 subcellular localization is mainly nuclear, but cytoplasmic staining has also been reported, the latter being associated with mitochondria and/or presence within the endoplasmic reticulum. It is not by chance that both expression and subcellular localization are altered in several metabolic and proliferative disorders, such as in tumors and aging. Moreover, a fundamental role played by different posttranslational modifications in modulating APE1/Ref-1 functional activity is becoming evident. In the present review, we tried to put together a growing body of information concerning APE1/Ref-1's different functions, shedding new light on present and future directions to understand fully this unique molecule.
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Affiliation(s)
- Gianluca Tell
- Department of Biomedical Sciences and Technologies, University of Udine, Piazzale Kolbe 4, 33100 Udine, Italy.
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7
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Bender AT, Ostenson CL, Wang EH, Beavo JA. Selective up-regulation of PDE1B2 upon monocyte-to-macrophage differentiation. Proc Natl Acad Sci U S A 2005; 102:497-502. [PMID: 15625104 PMCID: PMC544304 DOI: 10.1073/pnas.0408535102] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a major regulator of monocyte to macrophage differentiation. In both humans and mice, the main phenotype of decreased GM-CSF function is pulmonary proteinosis due to aberrant function of alveolar macrophages. Recently, this cytokine has been shown to up-regulate a cyclic nucleotide phosphodiesterase, PDE1B. Two PDE1B variants with unique N-terminal sequences, PDE1B1 and PDE1B2, have been identified. Here, we report that the previously uncharacterized PDE1B2 is selectively increased by GM-CSF by stimulation of transcription at a previously unknown transcriptional start site. Analysis of the exon and intron organization of the PDE1B gene reveals that PDE1B2 has a different N-terminal sequence because of a separate first exon that is located 11.5 kb downstream from the PDE1B1 first exon. By using 5'-RACE, alignment of EST sequences, and a luciferase-reporter system, we provide evidence that PDE1B2 has a separate transcriptional start site from PDE1B1 that can be activated by monocyte differentiation. Furthermore, IL-4 treatment in the presence of GM-CSF, which shifts the differentiation from a macrophage to a dendritic cell phenotype, suppresses the up-regulation of PDE1B2. Induction of PDE1B2 is also found in T cells upon activation by PHA. Therefore, PDE1B2 may have a regulatory role in multiple immune cell types. Last, characterization of the catalytic properties of recombinant PDE1B2 shows that it prefers cGMP over cAMP as a substrate and, thus, is likely to regulate cGMP in macrophages. Also, PDE1B2 has a nearly 3-fold lower EC(50) for activation by calmodulin than PDE1B1.
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Affiliation(s)
- Andrew T Bender
- Department of Pharmacology, University of Washington Medical School, Seattle, WA 98195-7280, USA
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8
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Abstract
The alveolar macrophage responds to bacterial infection with the production of inflammatory mediators that include TNFalpha. Early production of TNFalpha results in increased bacterial clearance, whereas too much TNFalpha results in many of the hallmarks of bacterial sepsis. TNFalpha production is regulated at many levels, including multiple signaling pathways, that lead to transcription, translation, and release of functional TNFalpha. Interactions of mitogen-activated protein (MAP) kinases, lipid signaling pathways, and oxidant-mediated mechanisms regulate the response of alveolar macrophages to infection. Animal models of sepsis support the central role played by macrophage-derived TNFalpha in sepsis.
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Affiliation(s)
- Martha M Monick
- Department of Medicine, University of Iowa College of Medicine and Veterans Administration Medical Center, Iowa City, Iowa, USA.
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9
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Nguyen C, Teo JL, Matsuda A, Eguchi M, Chi EY, Henderson WR, Kahn M. Chemogenomic identification of Ref-1/AP-1 as a therapeutic target for asthma. Proc Natl Acad Sci U S A 2003; 100:1169-73. [PMID: 12552119 PMCID: PMC298745 DOI: 10.1073/pnas.0437889100] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Asthma is characterized by an oxidantantioxidant imbalance in the lungs leading to activation of redox-sensitive transcription factors, nuclear factor kappaB (NF-kappaB), and activator protein-1 (AP-1). To develop therapeutic strategies for asthma, we used a chemogenomics approach to screen for small molecule inhibitor(s) of AP-1 transcription. We developed a beta-strand mimetic template that acts as a reversible inhibitor (pseudosubstrate) of redox proteins. This template incorporates an enedione moiety to trap reactive cysteine nucleophiles in the active sites of redox proteins. Specificity for individual redox factors was achieved through variations in X and Y functionality by using a combinatorial library approach. A limited array (2 x 6) was constructed where X was either NHCH(3) or NHCH(2) Ph and Y was methyl, phenyl, m-cyanophenyl, m-nitrophenyl, m-acetylaniline, or m-methylbenzoate. These analogs were evaluated for their ability to inhibit transcription in transiently transfected human lung epithelial A549 cells from either an AP-1 or NF-kappaB reporter. A small-molecule inhibitor, PNRI-299, was identified that selectively inhibited AP-1 transcription (IC(50) of 20 microM) without affecting NF-kappaB transcription (up to 200 microM) or thioredoxin (up to 200 microM). The molecular target of PNRI-299 was determined to be the oxidoreductase, redox effector factor-1 by an affinity chromatography approach. The selective redox effector factor-1 inhibitor, PNRI-299, significantly reduced airway eosinophil infiltration, mucus hypersecretion, edema, and IL-4 levels in a mouse asthma model. These data validate AP-1 as an important therapeutic target in allergic airway inflammation.
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Affiliation(s)
- Cu Nguyen
- Pacific Northwest Research Institute, 720 Broadway, Seattle, WA 98122, USA
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10
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Reddy SPM, Mossman BT. Role and regulation of activator protein-1 in toxicant-induced responses of the lung. Am J Physiol Lung Cell Mol Physiol 2002; 283:L1161-78. [PMID: 12424143 DOI: 10.1152/ajplung.00140.2002] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Aberrant cell proliferation and differentiation after toxic injury to airway epithelium can lead to the development of various lung diseases including cancer. The activator protein-1 (AP-1) transcription factor, composed of mainly Jun-Jun and Jun-Fos protein dimers, acts as an environmental biosensor to various external toxic stimuli and regulates gene expression involved in various biological processes. Gene disruption studies indicate that the AP-1 family members c-jun, junB, and fra1 are essential for embryonic development, whereas junD, c-fos, and fosB are required for normal postnatal growth. However, broad or target-specific transgenic overexpression of the some of these proteins gives very distinct phenotype(s), including tumor formation. This implies that, although they are required for normal cellular processes, their abnormal activation after toxic injury can lead to the pathogenesis of the lung disease. Consistent with this view, various environmental toxicants and carcinogens differentially regulate Jun and Fos expression in cells of the lung both in vivo and in vitro. Moreover, Jun and Fos proteins distinctly bind to the promoter regions of a wide variety of genes to differentially regulate their expression in epithelial injury, repair, and differentiation. Importantly, lung tumors induced by various carcinogens display a sustained expression of certain AP-1 family members. Therefore a better understanding of the mechanisms of regulation and functional role(s), as well as identification of target genes of members of the AP-1 family in airway epithelial cells, will provide additional insight into toxicant-induced lung diseases. These studies might offer a unique opportunity to use AP-1 family members and transactivation as potential diagnostic markers or drug targets for early detection and/or prevention of various lung diseases.
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Affiliation(s)
- Sekhar P M Reddy
- Department of Environmental Health Sciences and Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University, Baltimore, Maryland 21205, USA.
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11
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Rooney CP, Denning GM, Davis BP, Flaherty DM, Chiorini JA, Zabner J. Bronchoalveolar fluid is not a major hindrance to virus-mediated gene therapy in cystic fibrosis. J Virol 2002; 76:10437-43. [PMID: 12239320 PMCID: PMC136549 DOI: 10.1128/jvi.76.20.10437-10443.2002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Successfully targeting the airway epithelium is essential for gene therapy of some pulmonary diseases. However, the airway epithelium is resistant to virus-mediated gene transfer with commonly used vectors. Vectors that interact with endogenously expressed receptors on the apical surface significantly increase gene transfer efficiency. However, other endogenous components involved in host immunity may hinder virus-mediated gene transfer. We tested the effect of bronchoalveolar lavage liquid (BAL) from patients with cystic fibrosis (CF), BAL from subjects without CF (non-CF BAL), Pseudomonas aeruginosa-derived proteins, and an array of inflammatory proteins on gene transfer mediated by adeno-associated virus type 5 (AAV5) and adenovirus targeted to an apically expressed glycosylphosphatidylinositol-modified coxsackie-adenovirus receptor. We found that neither CF BAL nor its components had a significant effect on gene transfer to human airway epithelium by these vectors. Non-CF BAL significantly impaired adenovirus-mediated gene transfer. Removal of immunoglobulins in non-CF BAL restored gene transfer efficiency. As virus vectors are improved and mechanisms of humoral immunity are elucidated, barriers to successful gene therapy found in the complex environment of the human lung can be circumvented.
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Affiliation(s)
- C P Rooney
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, IA 52242, USA
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12
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Flaherty DM, Monick MM, Carter AB, Peterson MW, Hunninghake GW. Oxidant-mediated increases in redox factor-1 nuclear protein and activator protein-1 DNA binding in asbestos-treated macrophages. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:5675-81. [PMID: 12023366 DOI: 10.4049/jimmunol.168.11.5675] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Alveolar macrophages have been implicated in the pathogenesis of a number of acute and chronic lung disorders. We have previously shown that normal human alveolar macrophages exhibit decreased DNA binding activity of the transcription factor, AP-1, compared with monocytes. Furthermore, this decrease in AP-1 DNA binding appears to be due to a decrease in the redox active protein, redox factor (Ref)-1. Ref-1 is an important redox regulator of a number of transcription factors, including NF-kappaB and AP-1. In this study we evaluated the role of asbestos, a prototypic model of chronic fibrotic lung disease, in Ref-1 expression and activity. We found that incubation with low concentrations of crocidolite asbestos (0.5-1.25 microg/cm(2)) resulted in an increase in nuclear Ref-1 protein after 5 min, with a persistent elevation in protein up to 24 h. Additionally, an increase in nuclear Ref-1 could be induced by treating the cells with an oxidant-generating stimulus (iron loading plus PMA) and inhibited by diphenyleneiodonium chloride, an inhibitor of NADPH oxidase. The asbestos-induced accumulation of nuclear Ref-1 was associated with an increase in AP-1 DNA binding activity. These findings suggest that an exposure associated with fibrotic lung disease, i.e., asbestos, modulates accumulation of nuclear Ref-1 in macrophages, and that this effect is mediated by an oxidant stimulus.
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Affiliation(s)
- Dawn M Flaherty
- Department of Internal Medicine, University of Iowa College of Medicine and Veterans Affairs Medical Center, Iowa City, IA 52243, USA.
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13
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Flaherty DM, Monick MM, Hunninghake GW. AP endonucleases and the many functions of Ref-1. Am J Respir Cell Mol Biol 2001; 25:664-7. [PMID: 11726389 DOI: 10.1165/ajrcmb.25.6.f220] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- D M Flaherty
- Department of Internal Medicine, University of Iowa College of Medicine and Veterans Administration Medical Center, Iowa City, Iowa 52242, USA.
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