101
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Abstract
Current tuberculosis (TB) therapies take too long and the regimens are complex and subject to adverse effects and drug-drug interactions with concomitant medications. The emergence of drug-resistant TB strains exacerbates the situation. Drug discovery for TB has resurged in recent years, generating compounds (hits) with varying potential for progression into developable leads. In parallel, advances have been made in understanding TB pathogenesis. It is now possible to apply the lessons learned from recent TB hit generation efforts and newly validated TB drug targets to generate the next wave of TB drug leads. Use of currently underexploited sources of chemical matter and lead-optimization strategies may also improve the efficiency of future TB drug discovery. Novel TB drug regimens with shorter treatment durations must target all subpopulations of Mycobacterium tuberculosis existing in an infection, including those responsible for the protracted TB treatment duration. This review proposes strategies for generating improved hits and leads that could help achieve this goal.
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102
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Liu Z, Reba S, Chen WD, Porwal SK, Boom WH, Petersen RB, Rojas R, Viswanathan R, Devireddy L. Regulation of mammalian siderophore 2,5-DHBA in the innate immune response to infection. ACTA ACUST UNITED AC 2014; 211:1197-213. [PMID: 24863067 PMCID: PMC4042634 DOI: 10.1084/jem.20132629] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bacteria can utilize a mammalian host siderophore to usurp host iron; however, the host can respond by down-regulating siderophore expression and up-regulating expression of an inhibitory siderophore-binding protein. Competition for iron influences host–pathogen interactions. Pathogens secrete small iron-binding moieties, siderophores, to acquire host iron. In response, the host secretes siderophore-binding proteins, such as lipocalin 24p3, which limit siderophore-mediated iron import into bacteria. Mammals produce 2,5-dihydroxy benzoic acid, a compound that resembles a bacterial siderophore. Our data suggest that bacteria use both mammalian and bacterial siderophores. In support of this idea, supplementation with mammalian siderophore enhances bacterial growth in vitro. In addition, mice lacking the mammalian siderophore resist E. coli infection. Finally, we show that the host responds to infection by suppressing siderophore synthesis while up-regulating lipocalin 24p3 expression via TLR signaling. Thus, reciprocal regulation of 24p3 and mammalian siderophore is a protective mechanism limiting microbial access to iron.
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Affiliation(s)
- Zhuoming Liu
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Scott Reba
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Wei-Dong Chen
- Genetics Branch, National Cancer Institute/National Institutes of Health, Bethesda, MD 20892
| | - Suheel Kumar Porwal
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
| | - W Henry Boom
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Robert B Petersen
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Roxana Rojas
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Rajesh Viswanathan
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
| | - L Devireddy
- Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106Case Comprehensive Cancer Center; Department of Pathology; Department of Medicine, Tuberculosis Research Institute and Division of Infectious Diseases; and Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
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103
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Abstract
Treatment of tuberculosis (TB) remains challenging, with lengthy treatment durations and complex drug regimens that are toxic and difficult to administer. Similar to the vast majority of antibiotics, drugs for Mycobacterium tuberculosis are directed against microbial targets. Although more effective drugs that target the bacterium may lead to faster cure of patients, it is possible that a biological limit will be reached that can be overcome only by adopting a fundamentally new treatment approach. TB regimens might be improved by including agents that target host pathways. Recent work on host-pathogen interactions, host immunity, and host-directed interventions suggests that supplementing anti-TB therapy with host modulators may lead to shorter treatment times, a reduction in lung damage caused by the disease, and a lower risk of relapse or reinfection. We undertook this review to identify molecular pathways of the host that may be amenable to modulation by small molecules for the treatment of TB. Although several approaches to augmenting standard TB treatment have been proposed, only a few have been explored in detail or advanced to preclinical and clinical studies. Our review focuses on molecular targets and inhibitory small molecules that function within the macrophage or other myeloid cells, on host inflammatory pathways, or at the level of TB-induced lung pathology.
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104
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Endogenous siderophore 2,5-dihydroxybenzoic acid deficiency promotes anemia and splenic iron overload in mice. Mol Cell Biol 2014; 34:2533-46. [PMID: 24777603 DOI: 10.1128/mcb.00231-14] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Eukaryotes produce a siderophore-like molecule via a remarkably conserved biosynthetic pathway. 3-OH butyrate dehydrogenase (BDH2), a member of the short-chain dehydrogenase (SDR) family of reductases, catalyzes a rate-limiting step in the biogenesis of the mammalian siderophore 2,5-dihydroxybenzoic acid (2,5-DHBA). Depletion of the mammalian siderophore by inhibiting expression of bdh2 results in abnormal accumulation of intracellular iron and mitochondrial iron deficiency in cultured mammalian cells, as well as in yeast cells and zebrafish embryos We disrupted murine bdh2 by homologous recombination to analyze the effect of bdh2 deletion on erythropoiesis and iron metabolism. bdh2 null mice developed microcytic anemia and tissue iron overload, especially in the spleen. Exogenous supplementation with 2,5-DHBA alleviates splenic iron overload in bdh2 null mice. Additionally, bdh2 null mice exhibit reduced serum iron. Although BDH2 has been proposed to oxidize ketone bodies, we found that BDH2 deficiency did not alter ketone body metabolism in vivo. In sum, our findings demonstrate a key role for BDH2 in erythropoiesis.
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105
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Zughaier SM, Kandler JL, Shafer WM. Neisseria gonorrhoeae modulates iron-limiting innate immune defenses in macrophages. PLoS One 2014; 9:e87688. [PMID: 24489950 PMCID: PMC3905030 DOI: 10.1371/journal.pone.0087688] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 01/01/2014] [Indexed: 11/19/2022] Open
Abstract
Neisseria gonorrhoeae is a strict human pathogen that causes the sexually transmitted infection termed gonorrhea. The gonococcus can survive extracellularly and intracellularly, but in both environments the bacteria must acquire iron from host proteins for survival. However, upon infection the host uses a defensive response by limiting the bioavailability of iron by a number of mechanisms including the enhanced expression of hepcidin, the master iron-regulating hormone, which reduces iron uptake from the gut and retains iron in macrophages. The host also secretes the antibacterial protein NGAL, which sequesters bacterial siderophores and therefore inhibits bacterial growth. To learn whether intracellular gonococci can subvert this defensive response, we examined expression of host genes that encode proteins involved in modulating levels of intracellular iron. We found that N. gonorrhoeae can survive in association (tightly adherent and intracellular) with monocytes and macrophages and upregulates a panel of its iron-responsive genes in this environment. We also found that gonococcal infection of human monocytes or murine macrophages resulted in the upregulation of hepcidin, NGAL, and NRAMP1 as well as downregulation of the expression of the gene encoding the short chain 3-hydroxybutyrate dehydrogenase (BDH2); BDH2 catalyzes the production of the mammalian siderophore 2,5-DHBA involved in chelating and detoxifying iron. Based on these findings, we propose that N. gonorrhoeae can subvert the iron-limiting innate immune defenses to facilitate iron acquisition and intracellular survival.
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Affiliation(s)
- Susu M. Zughaier
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
| | - Justin L. Kandler
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - William M. Shafer
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Laboratories of Microbial Pathogenesis, Department of Veterans Affairs Medical Center, Decatur, Georgia, United States of America
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106
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Abstract
Mycobacterium tuberculosis releases membrane vesicles packed with molecules that can modulate the immune response. Because environmental conditions often influence the production and content of bacterial vesicles, this study examined M. tuberculosis microvesicles released under iron limitation, a common condition faced by pathogens inside the host. The findings indicate that M. tuberculosis increases microvesicle production in response to iron restriction and that these microvesicles contain mycobactin, which can serve as an iron donor and supports replication of iron-starved mycobacteria. Consequently, the results revealed a role of microvesicles in iron acquisition in M. tuberculosis, which can be critical for survival in the host.
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107
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Interleukin-17-induced protein lipocalin 2 is dispensable for immunity to oral candidiasis. Infect Immun 2013; 82:1030-5. [PMID: 24343647 DOI: 10.1128/iai.01389-13] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Oropharyngeal candidiasis (OPC; thrush) is an opportunistic fungal infection caused by the commensal microbe Candida albicans. Immunity to OPC is strongly dependent on CD4+ T cells, particularly those of the Th17 subset. Interleukin-17 (IL-17) deficiency in mice or humans leads to chronic mucocutaneous candidiasis, but the specific downstream mechanisms of IL-17-mediated host defense remain unclear. Lipocalin 2 (Lcn2; 24p3; neutrophil gelatinase-associated lipocalin [NGAL]) is an antimicrobial host defense factor produced in response to inflammatory cytokines, particularly IL-17. Lcn2 plays a key role in preventing iron acquisition by bacteria that use catecholate-type siderophores, and lipocalin 2(-/-) mice are highly susceptible to infection by Escherichia coli and Klebsiella pneumoniae. The role of Lcn2 in mediating immunity to fungi is poorly defined. Accordingly, in this study, we evaluated the role of Lcn2 in immunity to oral infection with C. albicans. Lcn2 is strongly upregulated following oral infection with C. albicans, and its expression is almost entirely abrogated in mice with defective IL-17 signaling (IL-17RA(-/-) or Act1(-/-) mice). However, Lcn2(-/-) mice were completely resistant to OPC, comparably to wild-type (WT) mice. Moreover, Lcn2 deficiency mediated protection from OPC induced by steroid immunosuppression. Therefore, despite its potent regulation during C. albicans infection, Lcn2 is not required for immunity to mucosal candidiasis.
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108
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Silva-Gomes S, Vale-Costa S, Appelberg R, Gomes MS. Iron in intracellular infection: to provide or to deprive? Front Cell Infect Microbiol 2013; 3:96. [PMID: 24367768 PMCID: PMC3856365 DOI: 10.3389/fcimb.2013.00096] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 11/21/2013] [Indexed: 12/16/2022] Open
Abstract
Due to their chemical versatility, transition metals were incorporated as cofactors for several basic metabolic pathways in living organisms. This same characteristic makes them potentially harmful, since they can be engaged in deleterious reactions like Fenton chemistry. As such, organisms have evolved highly specialized mechanisms to supply their own metal needs while keeping their toxic potential in check. This dual character comes into play in host-pathogen interactions, given that the host can either deprive the pathogen of these key nutrients or exploit them to induce toxicity toward the invading agent. Iron stands as the prototypic example of how a metal can be used to limit the growth of pathogens by nutrient deprivation, a mechanism widely studied in Mycobacterium infections. However, the host can also take advantage of iron-induced toxicity to control pathogen proliferation, as observed in infections caused by Leishmania. Whether we may harness either of the two pathways for therapeutical purposes is still ill-defined. In this review, we discuss how modulation of the host iron availability impacts the course of infections, focusing on those caused by two relevant intracellular pathogens, Mycobacterium and Leishmania.
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Affiliation(s)
- Sandro Silva-Gomes
- Infection and Immunity Unit, Instituto de Biologia Molecular e Celular, Universidade do Porto Porto, Portugal ; Department of Molecular Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto Porto, Portugal
| | - Sílvia Vale-Costa
- Infection and Immunity Unit, Instituto de Biologia Molecular e Celular, Universidade do Porto Porto, Portugal ; Department of Molecular Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto Porto, Portugal
| | - Rui Appelberg
- Infection and Immunity Unit, Instituto de Biologia Molecular e Celular, Universidade do Porto Porto, Portugal ; Department of Molecular Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto Porto, Portugal
| | - Maria S Gomes
- Infection and Immunity Unit, Instituto de Biologia Molecular e Celular, Universidade do Porto Porto, Portugal ; Department of Molecular Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto Porto, Portugal
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109
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Lisher JP, Giedroc DP. Manganese acquisition and homeostasis at the host-pathogen interface. Front Cell Infect Microbiol 2013; 3:91. [PMID: 24367765 PMCID: PMC3851752 DOI: 10.3389/fcimb.2013.00091] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/18/2013] [Indexed: 11/21/2022] Open
Abstract
Pathogenic bacteria acquire transition metals for cell viability and persistence of infection in competition with host nutritional defenses. The human host employs a variety of mechanisms to stress the invading pathogen with both cytotoxic metal ions and oxidative and nitrosative insults while withholding essential transition metals from the bacterium. For example, the S100 family protein calprotectin (CP) found in neutrophils is a calcium-activated chelator of extracellular Mn and Zn and is found in tissue abscesses at sites of infection by Staphylococcus aureus. In an adaptive response, bacteria have evolved systems to acquire the metals in the face of this competition while effluxing excess or toxic metals to maintain a bioavailability of transition metals that is consistent with a particular inorganic "fingerprint" under the prevailing conditions. This review highlights recent biological, chemical and structural studies focused on manganese (Mn) acquisition and homeostasis and connects this process to oxidative stress resistance and iron (Fe) availability that operates at the human host-pathogen interface.
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Affiliation(s)
- John P. Lisher
- Graduate Program in Biochemistry, Indiana UniversityBloomington, IN, USA
| | - David P. Giedroc
- Graduate Program in Biochemistry, Indiana UniversityBloomington, IN, USA
- Department of Chemistry, Indiana UniversityBloomington, IN, USA
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110
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EGCG inhibit chemical reactivity of iron through forming an Ngal-EGCG-iron complex. Biometals 2013; 26:1041-50. [PMID: 24158698 DOI: 10.1007/s10534-013-9681-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 10/18/2013] [Indexed: 12/15/2022]
Abstract
Accumulated evidence indicates that the interconversion of iron between ferric (Fe(3+)) and ferrous (Fe(2+)) can be realized through interaction with reactive oxygen species in the Fenton and Haber-Weiss reactions and thereby physiologically effects redox cycling. The imbalance of iron and ROS may eventually cause tissue damage such as renal proximal tubule injury and necrosis. Many approaches were exploited to ameliorate the oxidative stress caused by the imbalance. (-)-Epigallocatechin-3-gallate, the most active and most abundant catechin in tea, was found to be involved in the protection of a spectrum of renal injuries caused by oxidative stress. Most of studies suggested that EGCG works as an antioxidant. In this paper, Multivariate analysis of the LC-MS data of tea extracts and binding assays showed that the tea polyphenol EGCG can form stable complex with iron through the protein Ngal, a biomarker of acute kidney injury. UV-Vis and Luminescence spectrum methods showed that Ngal can inhibit the chemical reactivity of iron and EGCG through forming an Ngal-EGCG-iron complex. In thinking of the interaction of iron and ROS, we proposed that EGCG may work as both antioxidant and Ngal binding siderphore in protection of kidney from injuries.
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111
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Dittrich AM, Meyer HA, Hamelmann E. The role of lipocalins in airway disease. Clin Exp Allergy 2013; 43:503-11. [PMID: 23600540 DOI: 10.1111/cea.12025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The pathogenesis of allergic airway inflammation and disease is complex and still not fully understood. Many cells, factors and mediators are involved in the different aspects of induction, maintenance and persistence of airway inflammation. The heterogeneity and redundancy of this system is one of the main reasons why novel therapeutic targets focusing on the pathogenesis of asthma only hesitantly reach the market and clinical application. Thus, it seems mandatory that we proceed in our efforts to better understand this micro cosmos to succeed in the development of safe and effective drugs for the treatment of more severe and refractory forms of asthma and chronic obstructive pulmonary disease. One of the more recently discovered mediators in the context of airway inflammation are the lipocalins (Lcns). They are a family of proteins that share functional and structural similarities and are involved in the transport of small hydrophobic molecules such as steroids and lipids into the cell. Lcns are found in many different cell types from plants and bacteria through invertebrate cells to cells of vertebrate origin. The purpose of this review is to summarize the role of Lcns in airway diseases, focusing on allergic and infectious inflammation. In particular, we will summarize the present knowledge about Lipocalin 1 and Lipocalin 2, where exciting new discoveries in the recent years have highlighted their role in pulmonary disease and infection. This new class of proteins is another putative candidate for the development of novel drugs against airway inflammation.
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Affiliation(s)
- A M Dittrich
- Junior Research Group, Allergic Sensitization, Medical School Hannover, Hannover, Germany
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112
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Allred BE, Correnti C, Clifton MC, Strong RK, Raymond KN. Siderocalin outwits the coordination chemistry of vibriobactin, a siderophore of Vibrio cholerae. ACS Chem Biol 2013; 8:1882-7. [PMID: 23755875 DOI: 10.1021/cb4002552] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human protein siderocalin (Scn) inhibits bacterial iron acquisition by binding catechol siderophores. Several pathogenic bacteria respond by making stealth siderophores that are not recognized by Scn. Fluvibactin and vibriobactin, respectively of Vibrio fluvialis and Vibrio cholerae , include an oxazoline adjacent to a catechol. This chelating unit binds iron either in a catecholate or a phenolate-oxazoline coordination mode. The latter has been suggested to make vibriobactin a stealth siderophore without directly identifying the coordination mode in relation to Scn binding. We use Scn binding assays with the two siderophores and two oxazoline-substituted analogs and the crystal structure of Fe-fluvibactin:Scn to show that the oxazoline does not prevent Scn binding; hence, vibriobactin is not a stealth siderophore. We show that the phenolate-oxazoline coordination mode is present at physiological pH and is not bound by Scn. However, Scn binding shifts the coordination to the catecholate mode and thereby inactivates this siderophore.
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Affiliation(s)
- Benjamin E. Allred
- Department of Chemistry, University of California, Berkeley, California 94720-1460,
United States
| | - Colin Correnti
- Division
of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington
98109, United States
| | - Matthew C. Clifton
- Division
of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington
98109, United States
| | - Roland K. Strong
- Division
of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington
98109, United States
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, California 94720-1460,
United States
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113
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Liu Z, Petersen R, Devireddy L. Impaired neutrophil function in 24p3 null mice contributes to enhanced susceptibility to bacterial infections. THE JOURNAL OF IMMUNOLOGY 2013; 190:4692-706. [PMID: 23543755 DOI: 10.4049/jimmunol.1202411] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Lipocalin 24p3 (24p3) is a neutrophil secondary granule protein. 24p3 is also a siderocalin, which binds several bacterial siderophores. It was therefore proposed that synthesis and secretion of 24p3 by stimulated macrophages or release of 24p3 upon neutrophil degranulation sequesters iron-laden siderophores to attenuate bacterial growth. Accordingly, 24p3-deficient mice are susceptible to bacterial pathogens for which siderophores would normally be chelated by 24p3. Specific granule deficiency (SGD) is a rare congenital disorder characterized by complete absence of proteins in secondary granules. Neutrophils from SGD patients, who are prone to bacterial infections, lack normal functions, but the potential role of 24p3 in neutrophil dysfunction in SGD is not known. In this study, we show that neutrophils from mice genetically deficient for lipocalin 24p3 (24p3(-/-)) are defective in many neutrophil functions. Specifically, neutrophils in 24p3(-/-) mice do not extravasate to sites of infection and are defective for chemotaxis. A transcriptome analysis revealed that genes that control cytoskeletal reorganization are selectively suppressed in 24p3(-/-) neutrophils. Additionally, small regulatory RNAs (microRNAs) that control upstream regulators of cytoskeletal proteins are also increased in 24p3(-/-) neutrophils. Further, 24p3(-/-) neutrophils failed to phagocytose bacteria, which may account for the enhanced sensitivity of 24p3(-/-) mice to both intracellular (Listeria monocytogenes) and extracellular (Candida albicans and Staphylococcus aureus) pathogens. Listeria does not secrete siderophores, and additionally, the siderophore secreted by Candida is not sequestered by 24p3. Therefore, the heightened sensitivity of 24p3(-/-) mice to these pathogens is not due to sequestration of siderophores limiting iron availability, but is a consequence of impaired neutrophil function.
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Affiliation(s)
- Zhuoming Liu
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
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114
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Abstract
Iron is a redox active metal which is abundant in the Earth's crust. It has played a key role in the evolution of living systems and as such is an essential element in a wide range of biological phenomena, being critical for the function of an enormous array of enzymes, energy transduction mechanisms, and oxygen carriers. The redox nature of iron renders the metal toxic in excess and consequently all biological organisms carefully control iron levels. In this overview the mechanisms adopted by man to control body iron levels are described.Low body iron levels are related to anemia which can be treated by various forms of iron fortification and supplementation. Elevated iron levels can occur systemically or locally, each giving rise to specific symptoms. Systemic iron overload results from either the hyperabsorption of iron or regular blood transfusion and can be treated by the use of a selection of iron chelating molecules. The symptoms of many forms of neurodegeneration are associated with elevated levels of iron in certain regions of the brain and iron chelation therapy is beginning to find an application in the treatment of such diseases. Iron chelators have also been widely investigated for the treatment of cancer, tuberculosis, and malaria. In these latter studies, selective removal of iron from key enzymes or iron binding proteins is sought. Sufficient selectivity between the invading organism and the host has yet to be established for such chelators to find application in the clinic.Iron chelation for systemic iron overload and iron supplementation therapy for the treatment of various forms of anemia are now established procedures in clinical medicine. Chelation therapy may find an important role in the treatment of various neurodegenerative diseases in the near future.
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115
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Virzì GM, Clementi A, de Cal M, Cruz DN, Ronco C. Genomics and Biological Activity of Neutrophil Gelatinase-Associated Lipocalin in Several Clinical Settings. Blood Purif 2013; 35:139-43. [DOI: 10.1159/000346100] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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116
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Guglani L, Gopal R, Rangel-Moreno J, Junecko BF, Lin Y, Berger T, Mak TW, Alcorn JF, Randall TD, Reinhart TA, Chan YR, Khader SA. Lipocalin 2 regulates inflammation during pulmonary mycobacterial infections. PLoS One 2012. [PMID: 23185529 PMCID: PMC3502292 DOI: 10.1371/journal.pone.0050052] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Pulmonary tuberculosis (TB), caused by the intracellular bacteria Mycobacterium tuberculosis, is a worldwide disease that continues to kill more than 1.5 million people every year worldwide. The accumulation of lymphocytes mediates the formation of the tubercle granuloma in the lung and is crucial for host protection against M.tuberculosis infection. However, paradoxically the tubercle granuloma is also the basis for the immunopathology associated with the disease and very little is known about the regulatory mechanisms that constrain the inflammation associated with the granulomas. Lipocalin 2 (Lcn2) is a member of the lipocalin family of proteins and binds to bacterial siderophores thereby sequestering iron required for bacterial growth. Thus far, it is not known whether Lcn2 plays a role in the inflammatory response to mycobacterial pulmonary infections. In the present study, using models of acute and chronic mycobacterial pulmonary infections, we reveal a novel role for Lcn2 in constraining T cell lymphocytic accumulation and inflammation by inhibiting inflammatory chemokines, such as CXCL9. In contrast, Lcn2 promotes neutrophil recruitment during mycobacterial pulmonary infection, by inducing G-CSF and KC in alveolar macrophages. Importantly, despite a common role for Lcn2 in regulating chemokines during mycobacterial pulmonary infections, Lcn2 deficient mice are more susceptible to acute M.bovis BCG, but not low dose M.tuberculosis pulmonary infection.
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Affiliation(s)
- Lokesh Guglani
- Division of Pulmonary Medicine, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Radha Gopal
- Division of Infectious Diseases, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Javier Rangel-Moreno
- Division of Allergy, Immunology and Rheumatology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Beth Fallert Junecko
- Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Yinyao Lin
- Division of Infectious Diseases, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Thorsten Berger
- The Campbell Family Institute for Breast Cancer Research and the Ontario Cancer Institute, University Health Network, Toronto, Canada
| | - Tak W. Mak
- The Campbell Family Institute for Breast Cancer Research and the Ontario Cancer Institute, University Health Network, Toronto, Canada
| | - John F. Alcorn
- Division of Pulmonary Medicine, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Troy D. Randall
- Division of Allergy, Immunology and Rheumatology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Todd A. Reinhart
- Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Yvonne R. Chan
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Shabaana A. Khader
- Division of Infectious Diseases, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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117
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Garénaux A, Houle S, Folch B, Dallaire G, Truesdell M, Lépine F, Doucet N, Dozois CM. Avian lipocalin expression in chickens following Escherichia coli infection and inhibition of avian pathogenic Escherichia coli growth by Ex-FABP. Vet Immunol Immunopathol 2012; 152:156-67. [PMID: 23102565 DOI: 10.1016/j.vetimm.2012.09.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Avian pathogenic Escherichia coli (APEC) causes respiratory disease and sepsis in poultry. To persist in its host, E. coli requires essential nutrients including iron. Since iron is limited in extra-intestinal tissues, E. coli produces siderophores, small molecules with high affinity for ferric iron, to sequester this essential nutrient. To counter bacterial siderophore systems, mammalian hosts secrete siderocalin (also called lipocalin 2 or NGAL), which binds ferric-siderophore complexes rendering them unavailable to bacteria. In humans and mice, siderocalin is known to play a role in primary defense against bacterial infections. In poultry, 4 proteins display homology to the human NGAL (CALβ, CALγ, Ggal-C8GC and Ex-FABP). The function and expression of the genes coding for these 4 proteins during infection by APEC is still unknown. Expression levels of these genes were determined by quantitative RT-PCR using RNA extracted from lungs, livers and spleens of healthy 3-week-old chickens and chickens infected with APEC. The gene coding for Ex-FABP was overexpressed in all organs tested. It was significantly more overexpressed in the lungs and liver than in the spleen (37.3 and 27.3 times versus 11.5 times, respectively). The genes coding for Calβ and Calγ were also found significantly overexpressed in the liver (27 and 8.2 times, respectively). To confirm the function of Ex-FABP as a siderocalin, the gene coding for this protein was cloned in an expression vector and the protein was purified. In vitro growth inhibition of E. coli strains by Ex-FABP was assayed in parallel with growth inhibition caused by human siderocalin. Purified Ex-FABP inhibited growth of E. coli K-12, which only produces the siderophore enterobactin. However, E. coli strains producing pathogen-associated siderophores including salmochelins (glucosylated enterobactin), aerobactin and yersiniabactin grew normally in the presence of Ex-FABP. These results indicate that Ex-FABP is an avian siderocalin with a siderophore-binding activity similar to that of human siderocalin and that pathogen-specific siderophores are required by APEC to overcome this innate defense protein in poultry.
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Affiliation(s)
- Amélie Garénaux
- INRS-Institut Armand Frappier, Université du Québec, 531 boul. des Prairies, Laval, Québec, Canada
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Pyoverdine, the Major Siderophore in Pseudomonas aeruginosa, Evades NGAL Recognition. Interdiscip Perspect Infect Dis 2012; 2012:843509. [PMID: 22973307 PMCID: PMC3438788 DOI: 10.1155/2012/843509] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Accepted: 07/26/2012] [Indexed: 12/20/2022] Open
Abstract
Pseudomonas aeruginosa is the most common pathogen that persists in the cystic fibrosis lungs. Bacteria such as P. aeruginosa secrete siderophores (iron-chelating molecules) and the host limits bacterial growth by producing neutrophil-gelatinase-associated lipocalin (NGAL) that specifically scavenges bacterial siderophores, therefore preventing bacteria from establishing infection. P. aeruginosa produces a major siderophore known as pyoverdine, found to be important for bacterial virulence and biofilm development. We report that pyoverdine did not bind to NGAL, as measured by tryptophan fluorescence quenching, while enterobactin bound to NGAL effectively causing a strong response. The experimental data indicate that pyoverdine evades NGAL recognition. We then employed a molecular modeling approach to simulate the binding of pyoverdine to human NGAL using NGAL's published crystal structures. The docking of pyoverdine to NGAL predicted nine different docking positions; however, neither apo- nor ferric forms of pyoverdine docked into the ligand-binding site in the calyx of NGAL where siderophores are known to bind. The molecular modeling results offer structural support that pyoverdine does not bind to NGAL, confirming the results obtained in the tryptophan quenching assay. The data suggest that pyoverdine is a stealth siderophore that evades NGAL recognition allowing P. aeruginosa to establish chronic infections in CF lungs.
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119
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Correnti C, Richardson V, Sia AK, Bandaranayake AD, Ruiz M, Rahmanto YS, Kovačević Ž, Clifton MC, Holmes MA, Kaiser BK, Barasch J, Raymond KN, Richardson DR, Strong RK. Siderocalin/Lcn2/NGAL/24p3 does not drive apoptosis through gentisic acid mediated iron withdrawal in hematopoietic cell lines. PLoS One 2012; 7:e43696. [PMID: 22928018 PMCID: PMC3424236 DOI: 10.1371/journal.pone.0043696] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/24/2012] [Indexed: 12/19/2022] Open
Abstract
Siderocalin (also lipocalin 2, NGAL or 24p3) binds iron as complexes with specific siderophores, which are low molecular weight, ferric ion-specific chelators. In innate immunity, siderocalin slows the growth of infecting bacteria by sequestering bacterial ferric siderophores. Siderocalin also binds simple catechols, which can serve as siderophores in the damaged urinary tract. Siderocalin has also been proposed to alter cellular iron trafficking, for instance, driving apoptosis through iron efflux via BOCT. An endogenous siderophore composed of gentisic acid (2,5-dihydroxybenzoic acid) substituents was proposed to mediate cellular efflux. However, binding studies reported herein contradict the proposal that gentisic acid forms high-affinity ternary complexes with siderocalin and iron, or that gentisic acid can serve as an endogenous siderophore at neutral pH. We also demonstrate that siderocalin does not induce cellular iron efflux or stimulate apoptosis, questioning the role siderocalin plays in modulating iron metabolism.
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Affiliation(s)
- Colin Correnti
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Vera Richardson
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, University of Sydney, NSW, Australia
| | - Allyson K. Sia
- Department of Chemistry, University of California, Berkeley, California, United States of America
| | - Ashok D. Bandaranayake
- Department of Immunology, University of Washington, Seattle, Washington, United States of America
| | - Mario Ruiz
- Instituto de Biología y Genética Molecular, Universidad de Valladolid, UVa-CSIC, Valladolid, Spain
| | - Yohan Suryo Rahmanto
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, University of Sydney, NSW, Australia
| | - Žaklina Kovačević
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, University of Sydney, NSW, Australia
| | - Matthew C. Clifton
- Emerald Biostructures, Bainbridge Island, Washington, United States of America
- Seattle Structural Genomics Center for Infectious Diseases (SSGCID), Washington, United States of America
| | - Margaret A. Holmes
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Brett K. Kaiser
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Jonathan Barasch
- College of Physicians and Surgeons of Columbia University, New York, New York, United States of America
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, California, United States of America
| | - Des R. Richardson
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, University of Sydney, NSW, Australia
- * E-mail: (DRR); (RKS)
| | - Roland K. Strong
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail: (DRR); (RKS)
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120
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Chakraborty S, Kaur S, Guha S, Batra SK. The multifaceted roles of neutrophil gelatinase associated lipocalin (NGAL) in inflammation and cancer. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1826:129-69. [PMID: 22513004 PMCID: PMC3362670 DOI: 10.1016/j.bbcan.2012.03.008] [Citation(s) in RCA: 280] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 03/06/2012] [Accepted: 03/08/2012] [Indexed: 02/06/2023]
Abstract
Neutrophil gelatinase associated lipocalin (NGAL), also known as oncogene 24p3, uterocalin, siderocalin or lipocalin 2, is a 24kDa secreted glycoprotein originally purified from a culture of mouse kidney cells infected with simian virus 40 (SV-40). Subsequent investigations have revealed that it is a member of the lipocalin family of proteins that transport small, hydrophobic ligands. Since then, NGAL expression has been reported in several normal tissues where it serves to provide protection against bacterial infection and modulate oxidative stress. Its expression is also dysregulated in several benign and malignant diseases. Its small size, secreted nature and relative stability have led to it being investigated as a diagnostic and prognostic biomarker in numerous diseases including inflammation and cancer. Functional studies, conducted primarily on lipocalin 2 (Lcn2), the mouse homologue of human NGAL have revealed that Lcn2 has a strong affinity for iron complexed to both bacterial siderophores (iron-binding proteins) and certain human proteins like norepinephrine. By sequestering iron-laden siderophores, Lcn2 deprives bacteria of a vital nutrient and thus inhibits their growth (bacteriostatic effect). In malignant cells, its proposed functions range from inhibiting apoptosis (in thyroid cancer cells), invasion and angiogenesis (in pancreatic cancer) to increasing proliferation and metastasis (in breast and colon cancer). Ectopic expression of Lcn2 also promotes BCR-ABL induced chronic myelogenous leukemia in murine models. By transporting iron into and out of the cell, NGAL also regulates iron responsive genes. Further, it stabilizes the proteolytic enzyme matrix metalloprotease-9 (MMP-9) by forming a complex with it, and thereby prevents its autodegradation. The factors regulating NGAL expression are numerous and range from pro-inflammatory cytokines like interleukins, tumor necrosis factor-α and interferons to vitamins like retinoic acid. The purpose of this review article is to examine the expression, structure, regulation and biological role of NGAL and critically assess its potential as a novel diagnostic and prognostic marker in both benign and malignant human diseases.
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Affiliation(s)
- Subhankar Chakraborty
- Department of Biochemistry and Molecular Biology, The UT MD Anderson Cancer Center, Houston, Texas
| | - Sukhwinder Kaur
- Department of Biochemistry and Molecular Biology, The UT MD Anderson Cancer Center, Houston, Texas
| | - Sushovan Guha
- Departments of Gastroenterology, Hepatology, and Nutrition, The UT MD Anderson Cancer Center, Houston, Texas
| | - Surinder K. Batra
- Department of Biochemistry and Molecular Biology, The UT MD Anderson Cancer Center, Houston, Texas
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE
- Eppley Institute for Cancer Research, Department of Surgery, University of Nebraska Medical Center, Omaha, NE
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121
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Cramer EP, Glenthøj A, Häger M, Juncker-Jensen A, Engelholm LH, Santoni-Rugiu E, Lund LR, Laerum OD, Cowland JB, Borregaard N. No effect of NGAL/lipocalin-2 on aggressiveness of cancer in the MMTV-PyMT/FVB/N mouse model for breast cancer. PLoS One 2012; 7:e39646. [PMID: 22737251 PMCID: PMC3380857 DOI: 10.1371/journal.pone.0039646] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 05/24/2012] [Indexed: 11/22/2022] Open
Abstract
NGAL/lipocalin-2 is a siderophore-binding protein that is highly expressed in several cancers. It is suggested to confer a proliferative advantage to cancer cells. Its expression has been correlated with aggressiveness of breast cancer as determined both in patients and in mouse breast cancer models. This was recently confirmed in two mouse models of spontaneous breast cancer in wild-type and lipocalin-2-deficient mice. We used a similar strategy using a different mouse strain. Lipocalin-2-deficient mice and mouse mammary tumor virus-polyoma middle T antigen (MMTV-PyMT) mice were crossed into the same FVB/N background. All mice developed tumors by week 8. The mice were sacrificed on week 13 and tissue was processed for biochemical and histological analysis. The total tumor volume and number of metastases were quantitated in 26 lipocalin-2-deficient mice and 34 wild-type controls. Lipocalin-2 expression in tumors of MMTV-PyMT-positive and wild-type mice was assessed by quantitative real-time PCR and by immunohistochemistry. The expression of the lipocalin-2 receptors 24p3R and megalin and of Mmp-9, transferrin receptor, and Bdh2 (a producer of a mammalian siderophore) were quantitated by real-time PCR. No significant difference was observed between wild-type and lipocalin-2-deficient mice. Lipocalin-2 was highly expressed in tumors from wild-type mice, but the expression did not correlate with tumor size. No effect of lipocalin-2 was observed with respect to time to tumor appearance, total tumor volume, or to the number of metastases. Histology and gelatinolytic activity of the mammary tumors did not differ between wild-type and lipocalin-2-deficient mice. We conclude that NGAL/lipocalin-2 does not invariably affect the aggressiveness of breast cancers as assessed in mouse models, thus questioning the role of lipocalin-2 in cancer development.
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Affiliation(s)
- Elisabeth P. Cramer
- The Granulocyte Research Laboratory, Department of Hematology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Andreas Glenthøj
- The Granulocyte Research Laboratory, Department of Hematology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Mattias Häger
- The Granulocyte Research Laboratory, Department of Hematology, Copenhagen University Hospital, Copenhagen, Denmark
| | - Anna Juncker-Jensen
- Finsen Laboratory, National University Hospital, Rigshospitalet, University of Copenhagen, Denmark
| | - Lars H. Engelholm
- Finsen Laboratory, National University Hospital, Rigshospitalet, University of Copenhagen, Denmark
| | - Eric Santoni-Rugiu
- Department of Pathology, National University Hospital, Rigshospitalet, University of Copenhagen, Denmark
| | - Leif R. Lund
- Department of Cellular and Molecular Medicine, University of Copenhagen, Denmark
| | - Ole D. Laerum
- Finsen Laboratory, National University Hospital, Rigshospitalet, University of Copenhagen, Denmark
- The Gade Institute, Section of Pathology, University of Bergen, Norway
| | - Jack B. Cowland
- The Granulocyte Research Laboratory, Department of Hematology, Copenhagen University Hospital, Copenhagen, Denmark
- * E-mail: (JBC); (NB)
| | - Niels Borregaard
- The Granulocyte Research Laboratory, Department of Hematology, Copenhagen University Hospital, Copenhagen, Denmark
- * E-mail: (JBC); (NB)
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122
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Paragas N, Qiu A, Hollmen M, Nickolas TL, Devarajan P, Barasch J. NGAL-Siderocalin in kidney disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1451-8. [PMID: 22728330 DOI: 10.1016/j.bbamcr.2012.06.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/06/2012] [Accepted: 06/13/2012] [Indexed: 12/11/2022]
Abstract
Kidney damage induces the expression of a myriad of proteins in the serum and in the urine. The function of these proteins in the sequence of damage and repair is now being studied in genetic models and by novel imaging techniques. One of the most intensely expressed proteins is lipocalin2, also called NGAL or Siderocalin. While this protein has been best studied by clinical scientists, only a few labs study its underlying metabolism and function in tissue damage. Structure-function studies, imaging studies and clinical studies have revealed that NGAL-Siderocalin is an endogenous antimicrobial with iron scavenging activity. This review discusses the "iron problem" of kidney damage, the tight linkage between kidney damage and NGAL-Siderocalin expression and the potential roles that NGAL-Siderocalin may serve in the defense of the urogenital system. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Affiliation(s)
- Neal Paragas
- College of Physicians & Surgeons of Columbia University, New York, NY, USA
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123
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Fritsche G, Nairz M, Libby SJ, Fang FC, Weiss G. Slc11a1 (Nramp1) impairs growth of Salmonella enterica serovar typhimurium in macrophages via stimulation of lipocalin-2 expression. J Leukoc Biol 2012; 92:353-9. [PMID: 22706314 DOI: 10.1189/jlb.1111554] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The expression of the cation transporter Nramp1 (Slc11a1) in late phagolysosomes confers resistance to infection with several intracellular pathogens, such as Salmonella enterica, in mice. The antimicrobial actions of Nramp1 are attributable, in part, to modulation of macrophage immune function and cellular iron metabolism--the latter affecting the availability of the essential nutrient iron for intraphagosomal bacteria. Here, we provide novel evidence that Nramp1 functionality increases the expression of the peptide Lcn2, which exerts its antimicrobial activity by scavenging iron-loaded bacterial siderophores and mediating iron efflux from macrophages. With the use of macrophage cell lines expressing functional or nonfunctional Nramp1, we found significantly elevated Lcn2 mRNA and protein levels in Nramp1-expressing cells. These resulted from Nramp1-mediated alterations in the production of ROS, which stimulated NF-κ B activity and subsequently, Lcn2 transcription. We observed that increased Lcn2 levels in primary Nramp1-positive macrophages resulted in a significant suppression of S. enterica serovar typhimurium growth. Stimulation of Lcn2 expression is a novel mechanism by which Nramp1 confers resistance against infection with the intracellular bacterium S. typhimurium.
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Affiliation(s)
- Gernot Fritsche
- Department of Internal Medicine I, Clinical Immunology and Infectious Diseases, Innsbruck Medical University, Innsbruck, Austria
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124
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Correnti C, Strong RK. Mammalian siderophores, siderophore-binding lipocalins, and the labile iron pool. J Biol Chem 2012; 287:13524-31. [PMID: 22389496 PMCID: PMC3340207 DOI: 10.1074/jbc.r111.311829] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Bacteria use tight-binding, ferric-specific chelators called siderophores to acquire iron from the environment and from the host during infection; animals use proteins such as transferrin and ferritin to transport and store iron. Recently, candidate compounds that could serve endogenously as mammalian siderophore equivalents have been identified and characterized through associations with siderocalin, the only mammalian siderophore-binding protein currently known. Siderocalin, an antibacterial protein, acts by sequestering iron away from infecting bacteria as siderophore complexes. Candidate endogenous siderophores include compounds that only effectively transport iron as ternary complexes with siderocalin, explaining pleiotropic activities in normal cellular processes and specific disease states.
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Affiliation(s)
- Colin Correnti
- From the Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
| | - Roland K. Strong
- From the Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
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125
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Galline Ex-FABP is an antibacterial siderocalin and a lysophosphatidic acid sensor functioning through dual ligand specificities. Structure 2012; 19:1796-806. [PMID: 22153502 DOI: 10.1016/j.str.2011.09.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 09/23/2011] [Accepted: 09/25/2011] [Indexed: 11/21/2022]
Abstract
Galline Ex-FABP was identified as another candidate antibacterial, catecholate siderophore binding lipocalin (siderocalin) based on structural parallels with the family archetype, mammalian Siderocalin. Binding assays show that Ex-FABP retains iron in a siderophore-dependent manner in both hypertrophic and dedifferentiated chondrocytes, where Ex-FABP expression is induced after treatment with proinflammatory agents, and specifically binds ferric complexes of enterobactin, parabactin, bacillibactin and, unexpectedly, monoglucosylated enterobactin, which does not bind to Siderocalin. Growth arrest assays functionally confirm the bacteriostatic effect of Ex-FABP in vitro under iron-limiting conditions. The 1.8 Å crystal structure of Ex-FABP explains the expanded specificity, but also surprisingly reveals an extended, multi-chambered cavity extending through the protein and encompassing two separate ligand specificities, one for bacterial siderophores (as in Siderocalin) at one end and one specifically binding copurified lysophosphatidic acid, a potent cell signaling molecule, at the other end, suggesting Ex-FABP employs dual functionalities to explain its diverse endogenous activities.
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126
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Li N, Zhang C, Li B, Liu X, Huang Y, Xu S, Gu L. Unique iron coordination in iron-chelating molecule vibriobactin helps Vibrio cholerae evade mammalian siderocalin-mediated immune response. J Biol Chem 2012; 287:8912-9. [PMID: 22291019 PMCID: PMC3308770 DOI: 10.1074/jbc.m111.316034] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 01/24/2012] [Indexed: 11/06/2022] Open
Abstract
Iron is essential for the survival of almost all bacteria. Vibrio cholerae acquires iron through the secretion of a catecholate siderophore called vibriobactin. At present, how vibriobactin chelates ferric ion remains controversial. In addition, the mechanisms underlying the recognition of ferric vibriobactin by the siderophore transport system and its delivery into the cytoplasm specifically have not been clarified. In this study, we report the high-resolution structures of the ferric vibriobactin periplasmic binding protein ViuP and its complex with ferric vibriobactin. The holo-ViuP structure reveals that ferric vibriobactin does not adopt the same iron coordination as that of other catecholate siderophores such as enterobactin. The three catechol moieties donate five, rather than six, oxygen atoms as iron ligands. The sixth iron ligand is provided by a nitrogen atom from the second oxazoline ring. This kind of iron coordination results in the protrusion of the second catechol moiety and renders the electrostatic surface potential of ferric vibriobactin less negatively polarized compared with ferric enterobactin. To accommodate ferric vibriobactin, ViuP has a deeper subpocket to hold the protrusion of the second catechol group. This structural characteristic has not been observed in other catecholate siderophore-binding proteins. Biochemical data show that siderocalin, which is part of the mammalian innate immune system, cannot efficiently sequester ferric vibriobactin in vitro, although it can capture many catecholate siderophores with high efficiency. Our findings suggest that the unique iron coordination found in ferric vibriobactin may be utilized by some pathogenic bacteria to evade the siderocalin-mediated innate immune response of mammals.
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Affiliation(s)
- Ning Li
- From the State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100 and
| | - Conggang Zhang
- From the State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100 and
| | - Bingqing Li
- From the State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100 and
| | - Xiuhua Liu
- From the State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100 and
- the College of Life Sciences, Hebei University, Baoding 071002, China
| | - Yan Huang
- From the State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100 and
| | - Sujuan Xu
- From the State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100 and
| | - Lichuan Gu
- From the State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100 and
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127
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Cassat JE, Skaar EP. Metal ion acquisition in Staphylococcus aureus: overcoming nutritional immunity. Semin Immunopathol 2012; 34:215-35. [PMID: 22048835 PMCID: PMC3796439 DOI: 10.1007/s00281-011-0294-4] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 10/14/2011] [Indexed: 12/19/2022]
Abstract
Transition metals are essential nutrients to virtually all forms of life, including bacterial pathogens. In Staphylococcus aureus, metal ions participate in diverse biochemical processes such as metabolism, DNA synthesis, regulation of virulence factors, and defense against oxidative stress. As an innate immune response to bacterial infection, vertebrate hosts sequester transition metals in a process that has been termed "nutritional immunity." To successfully infect vertebrates, S. aureus must overcome host sequestration of these critical nutrients. The objective of this review is to outline the current knowledge of staphylococcal metal ion acquisition systems, as well as to define the host mechanisms of nutritional immunity during staphylococcal infection.
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Affiliation(s)
- James E. Cassat
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1161 21st Ave South, A-5102 MCN, Nashville, TN 37232-2363, USA
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128
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Chen C, Paw BH. Cellular and mitochondrial iron homeostasis in vertebrates. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1459-67. [PMID: 22285816 DOI: 10.1016/j.bbamcr.2012.01.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 01/07/2012] [Accepted: 01/07/2012] [Indexed: 02/08/2023]
Abstract
Iron plays an essential role in cellular metabolism and biological processes. However, due to its intrinsic redox activity, free iron is a potentially toxic molecule in cellular biochemistry. Thus, organisms have developed sophisticated ways to import, sequester, and utilize iron. The transferrin cycle is a well-studied iron uptake pathway that is important for most vertebrate cells. Circulating iron can also be imported into cells by mechanisms that are independent of transferrin. Once imported into erythroid cells, iron is predominantly consumed by the mitochondria for the biosynthesis of heme and iron sulfur clusters. This review focuses on canonical transferrin-mediated and the newly discovered, non-transferrin mediated iron uptake pathways, as well as, mitochondrial iron homeostasis in higher eukaryotes. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Affiliation(s)
- Caiyong Chen
- Department of Medicine, Hematology Division, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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129
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Lipidomic discovery of deoxysiderophores reveals a revised mycobactin biosynthesis pathway in Mycobacterium tuberculosis. Proc Natl Acad Sci U S A 2012; 109:1257-62. [PMID: 22232695 DOI: 10.1073/pnas.1109958109] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To measure molecular changes underlying pathogen adaptation, we generated a searchable dataset of more than 12,000 mass spectrometry events, corresponding to lipids and small molecules that constitute a lipidome for Mycobacterium tuberculosis. Iron is essential for M. tuberculosis survival, and the organism imports this metal using mycobactin and carboxymycobactin siderophores. Detection of an unexpected siderophore variant and deletions of genes for iron scavenging has led to a revised mycobactin biosynthesis model. An organism-wide search of the M. tuberculosis database for hypothetical compounds predicted by this model led to the discovery of two families of previously unknown lipids, designated monodeoxymycobactins and monodeoxycarboxymycobactins. These molecules suggest a revised biosynthetic model that alters the substrates and order of action of enzymes through the mycobactin biosynthetic pathway. We tested this model genetically by solving M. tuberculosis lipidomes after deletion of the iron-dependent regulator (ideR), mycobactin synthase B (mbtB), or mycobactin synthase G (mbtG). These studies show that deoxymycobactins are actively regulated during iron starvation, and also define essential roles of MbtG in converting deoxymycobactins to mycobactin and in promoting M. tuberculosis growth. Thus, lipidomics is an efficient discovery tool that informs genetic relationships, leading to a revised general model for the biosynthesis of these virulence-conferring siderophores.
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130
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Hoette TM, Clifton MC, Zawadzka AM, Holmes MA, Strong RK, Raymond KN. Immune interference in Mycobacterium tuberculosis intracellular iron acquisition through siderocalin recognition of carboxymycobactins. ACS Chem Biol 2011; 6:1327-31. [PMID: 21978368 PMCID: PMC3241878 DOI: 10.1021/cb200331g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The innate immune system antibacterial protein Siderocalin (Scn) binds ferric carboxymycobactin (CMB) and also several catecholate siderophores. Although the recognition of catecholates by Scn has been thoroughly investigated, the binding interactions of Scn with the full spectrum of CMB isoforms have not been studied. Here we show that Scn uses different binding modes for the limited subset of bound CMB isoforms, resulting in a range of binding affinities that are much weaker than other siderophore targets of Scn. Understanding the binding interaction between Scn and CMBs provides clues for the influence of Scn on mycobacterial iron acquisition.
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Affiliation(s)
- Trisha M. Hoette
- Department of Chemistry, University of California, Berkeley, California 94720-1460
| | - Matthew C. Clifton
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, 98109
| | - Anna M. Zawadzka
- Department of Chemistry, University of California, Berkeley, California 94720-1460
| | - Meg A. Holmes
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, 98109
| | - Roland K. Strong
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, 98109
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, California 94720-1460
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131
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Iron metabolism and the innate immune response to infection. Microbes Infect 2011; 14:207-16. [PMID: 22033148 DOI: 10.1016/j.micinf.2011.10.001] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 09/29/2011] [Accepted: 10/10/2011] [Indexed: 12/15/2022]
Abstract
Host antimicrobial mechanisms reduce iron availability to pathogens. Iron proteins influencing the innate immune response include hepcidin, lactoferrin, siderocalin, haptoglobin, hemopexin, Nramp1, ferroportin and the transferrin receptor. Numerous global health threats are influenced by iron status and provide examples of our growing understanding of the connections between infection and iron metabolism.
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132
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Rodrigues PN, Gomes SS, Neves JV, Gomes-Pereira S, Correia-Neves M, Nunes-Alves C, Stolte J, Sanchez M, Appelberg R, Muckenthaler MU, Gomes MS. Mycobacteria-induced anaemia revisited: A molecular approach reveals the involvement of NRAMP1 and lipocalin-2, but not of hepcidin. Immunobiology 2011; 216:1127-34. [DOI: 10.1016/j.imbio.2011.04.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 04/11/2011] [Accepted: 04/13/2011] [Indexed: 01/08/2023]
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133
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Abstract
My laboratory has been interested for some time in the influence of iron, a nutrient that is essential for both microbial pathogens and their mammalian hosts, on the course of infectious disease. Our studies indicate that alterations in the expression of host molecules that sequester or transport iron can have direct effects on pathogen growth and can also have an impact on the ability to mount normal immune responses. We have elucidated the mechanistic basis for some of these observations, and have started to apply our findings in strategies to control abnormalities of inflammation and iron metabolism. I will review here what we have learned about the interactions between iron and immunity and discuss the implications of the information that we have acquired.
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Affiliation(s)
- Bobby J Cherayil
- Mucosal Immunology Laboratory, MassGeneral Hospital for Children, Charlestown, MA 02129, USA.
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134
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Peuckert F, Ramos-Vega A, Miethke M, Schwörer C, Albrecht A, Oberthür M, Marahiel M. The Siderophore Binding Protein FeuA Shows Limited Promiscuity toward Exogenous Triscatecholates. ACTA ACUST UNITED AC 2011; 18:907-19. [DOI: 10.1016/j.chembiol.2011.05.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 04/14/2011] [Accepted: 05/04/2011] [Indexed: 11/24/2022]
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135
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Banerjee S, Farhana A, Ehtesham NZ, Hasnain SE. Iron acquisition, assimilation and regulation in mycobacteria. INFECTION GENETICS AND EVOLUTION 2011; 11:825-38. [PMID: 21414421 DOI: 10.1016/j.meegid.2011.02.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 02/25/2011] [Accepted: 02/28/2011] [Indexed: 11/28/2022]
Abstract
Iron is as crucial to the pathogen as it is to the host. The tuberculosis causing bacillus, Mycobacterium tuberculosis (M.tb), is an exceptionally efficient pathogen that has evolved proficient mechanisms to sequester iron from the host despite its thick mycolate-rich outer covering and a highly impermeable membrane of phagolysosome within which it persists inside an infected host macrophage. Further, both overindulgence and moderation of iron inside a host are a threat to mycobacterial persistence. While for removing iron from the host reservoirs, mycobacteria synthesize molecules that have several times higher affinity for iron than their host counterparts, they also synthesize molecules for efficient storage of excess iron. This is supported by tightly regulated iron dependent global gene expressions. In this review we discuss the various molecules and pathways evolved by mycobacteria for an efficient iron metabolism. We also discuss the less investigated players, like iron responsive proteins and iron responsive elements in mycobacteria, and highlight the lacunae in our current understanding of iron acquisition and utilization in mycobacteria with an ultimate aim to make iron metabolism as a possible anti-mycobacterial target.
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Affiliation(s)
- Sharmistha Banerjee
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
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136
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Nevitt T. War-Fe-re: iron at the core of fungal virulence and host immunity. Biometals 2011; 24:547-58. [PMID: 21399939 DOI: 10.1007/s10534-011-9431-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 02/22/2011] [Indexed: 12/21/2022]
Abstract
Iron acquisition is a bona fide virulence determinant. The successful colonization of the mammalian host requires that microorganisms overcome the Fe aridity of this milieu in which the levels of circulating Fe are maintained exceedingly low both through the compartmentalization of this nutrient within cells as well as the tight binding of Fe to host circulating proteins and ligands. Microbes notoriously employ multiple strategies for high affinity Fe acquisition from the host that rely either on the expression of receptors for host Fe-binding proteins and ligands, its reduction by cell surface reductases or the utilization of siderophores, small organic molecules with very high affinity for Fe(3+). This review will discuss the multiple mechanisms deployed by fungal pathogens in Fe acquisition focusing on the role of siderophore utilization in virulence as well as host immune strategies of iron withholding and emerging clinical evidence that human disorders of Fe homeostasis can act as modifiers of infectious disease.
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Affiliation(s)
- Tracy Nevitt
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA.
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137
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Viau A, El Karoui K, Laouari D, Burtin M, Nguyen C, Mori K, Pillebout E, Berger T, Mak TW, Knebelmann B, Friedlander G, Barasch J, Terzi F. Lipocalin 2 is essential for chronic kidney disease progression in mice and humans. J Clin Invest 2010; 120:4065-76. [PMID: 20921623 PMCID: PMC2964970 DOI: 10.1172/jci42004] [Citation(s) in RCA: 285] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 08/09/2010] [Indexed: 12/21/2022] Open
Abstract
Mechanisms of progression of chronic kidney disease (CKD), a major health care burden, are poorly understood. EGFR stimulates CKD progression, but the molecular networks that mediate its biological effects remain unknown. We recently showed that the severity of renal lesions after nephron reduction varied substantially among mouse strains and required activation of EGFR. Here, we utilized two mouse strains that react differently to nephron reduction--FVB/N mice, which develop severe renal lesions, and B6D2F1 mice, which are resistant to early deterioration--coupled with genome-wide expression to elucidate the molecular nature of CKD progression. Our results showed that lipocalin 2 (Lcn2, also known as neutrophil gelatinase-associated lipocalin [NGAL]), the most highly upregulated gene in the FVB/N strain, was not simply a marker of renal lesions, but an active player in disease progression. In fact, the severity of renal lesions was dramatically reduced in Lcn2-/- mice. We discovered that Lcn2 expression increased upon EGFR activation and that Lcn2 mediated its mitogenic effect during renal deterioration. EGFR inhibition prevented Lcn2 upregulation and lesion development in mice expressing a dominant negative EGFR isoform, and hypoxia-inducible factor 1α (Hif-1α) was crucially required for EGFR-induced Lcn2 overexpression. Consistent with this, cell proliferation was dramatically reduced in Lcn2-/- mice. These data are relevant to human CKD, as we found that LCN2 was increased particularly in patients who rapidly progressed to end-stage renal failure. Together our results uncover what we believe to be a novel function for Lcn2 and a critical pathway leading to progressive renal failure and cystogenesis.
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Affiliation(s)
- Amandine Viau
- INSERM U845, Centre de Recherche Croissance et Signalisation, Université Paris Descartes, Hôpital Necker Enfants Malades, Paris, France
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138
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Nairz M, Schroll A, Sonnweber T, Weiss G. The struggle for iron - a metal at the host-pathogen interface. Cell Microbiol 2010; 12:1691-702. [DOI: 10.1111/j.1462-5822.2010.01529.x] [Citation(s) in RCA: 283] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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139
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Witte E, Witte K, Warszawska K, Sabat R, Wolk K. Interleukin-22: a cytokine produced by T, NK and NKT cell subsets, with importance in the innate immune defense and tissue protection. Cytokine Growth Factor Rev 2010; 21:365-79. [PMID: 20870448 DOI: 10.1016/j.cytogfr.2010.08.002] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Interleukin (IL)-22 is a member of the IL-10 cytokine family that is produced by special immune cell populations, including Th22, Th1, and Th17 cells, classical and non-classical (NK-22) NK cells, NKT cells, and lymphoid tissue inducer cells. This cytokine does not influence cells of the hematopoietic lineage. Instead, its target cells are certain tissue cells from the skin, liver and kidney, and from organs of the respiratory and gastrointestinal systems. The main biological role of IL-22 includes the increase of innate immunity, protection from damage, and enhancement of regeneration. IL-22 can play either a protective or a pathogenic role in chronic inflammatory diseases depending on the nature of the affected tissue and the local cytokine milieu. This review highlights the primary effects of IL-22 on its target cells, its role in the defense against infections, in tumorigenesis, in inflammatory diseases and allergy as well as the potential of the therapeutic modulation of IL-22 action.
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Affiliation(s)
- Ellen Witte
- Interdisciplinary Group of Molecular Immunopathology, Dermatology/Medical Immunology, University Hospital Charité, Charitéplatz 1, 10117 Berlin, Germany
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140
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Coudevylle N, Geist L, Hötzinger M, Hartl M, Kontaxis G, Bister K, Konrat R. The v-myc-induced Q83 lipocalin is a siderocalin. J Biol Chem 2010; 285:41646-52. [PMID: 20826777 DOI: 10.1074/jbc.m110.123331] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Siderocalins are atypical lipocalins able to capture siderophores with high affinity. They contribute to the innate immune response by interfering with bacterial siderophore-mediated iron uptake but are also involved in numerous physiological processes such as inflammation, iron delivery, tissue differentiation, and cancer progression. The Q83 lipocalin was originally identified based on its overexpression in quail embryo fibroblasts transformed by the v-myc oncogene. We show here that Q83 is a siderocalin, binding the siderophore enterobactin with an affinity and mode of binding nearly identical to that of neutrophil gelatinase-associated lipocalin (NGAL), the prototypical siderocalin. This strengthens the role of siderocalins in cancer progression and inflammation. In addition, we also present the solution structure of Q83 in complex with intact enterobactin and a detailed analysis of the Q83 binding mode, including mutagenesis of the critical residues involved in enterobactin binding. These data provide a first insight into the molecular details of siderophore binding and delineate the common molecular properties defining the siderocalin protein family.
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Affiliation(s)
- Nicolas Coudevylle
- Department of Structural and Computational Biology, Max F Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
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141
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Wu H, Santoni-Rugiu E, Ralfkiaer E, Porse BT, Moser C, Høiby N, Borregaard N, Cowland JB. Lipocalin 2 is protective against E. coli pneumonia. Respir Res 2010; 11:96. [PMID: 20633248 PMCID: PMC2912245 DOI: 10.1186/1465-9921-11-96] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 07/15/2010] [Indexed: 02/07/2023] Open
Abstract
Background Lipocalin 2 is a bacteriostatic protein that binds the siderophore enterobactin, an iron-chelating molecule produced by Escherichia coli (E. coli) that is required for bacterial growth. Infection of the lungs by E. coli is rare despite a frequent exposure to this commensal bacterium. Lipocalin 2 is an effector molecule of the innate immune system and could therefore play a role in hindering growth of E. coli in the lungs. Methods Lipocalin 2 knock-out and wild type mice were infected with two strains of E. coli. The lungs were removed 48 hours post-infection and examined for lipocalin 2 and MMP9 (a myeloid marker protein) by immunohistochemical staining and western blotting. Bacterial numbers were assessed in the lungs of the mice at 2 and 5 days after infection and mortality of the mice was monitored over a five-day period. The effect of administering ferrichrome (an iron source that cannot be bound by lipocalin 2) along with E.coli was also examined. Results Intratracheal installation of E. coli in mice resulted in strong induction of lipocalin 2 expression in bronchial epithelium and alveolar type II pneumocytes. Migration of myeloid cells to the site of infection also contributed to an increased lipocalin 2 level in the lungs. Significant higher bacterial numbers were observed in the lungs of lipocalin 2 knock-out mice on days 2 and 5 after infection with E. coli (p < 0.05). In addition, a higher number of E. coli was found in the spleen of surviving lipocalin 2 knock-out mice on day 5 post-infection than in the corresponding wild-type mice (p < 0.05). The protective effect against E. coli infection in wild type mice could be counteracted by the siderophore ferrichrome, indicating that the protective effect of lipocalin 2 depends on its ability to sequester iron. Conclusions Lipocalin 2 is important for protection of airways against infection by E. coli.
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Affiliation(s)
- Hong Wu
- Granulocyte Research Laboratory, Rigshospitalet, Copenhagen, Denmark
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142
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Iron traffics in circulation bound to a siderocalin (Ngal)-catechol complex. Nat Chem Biol 2010; 6:602-9. [PMID: 20581821 PMCID: PMC2907470 DOI: 10.1038/nchembio.402] [Citation(s) in RCA: 244] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 05/27/2010] [Indexed: 02/06/2023]
Abstract
The lipocalins are secreted proteins that bind small organic molecules. Scn-Ngal (also known as neutrophil gelatinase associated lipocalin, siderocalin, lipocalin 2) sequesters bacterial iron chelators, called siderophores, and consequently blocks bacterial growth. However, Scn-Ngal is also prominently expressed in aseptic diseases, implying that it binds additional ligands and serves additional functions. Using chemical screens, crystallography and fluorescence methods, we report that Scn-Ngal binds iron together with a small metabolic product called catechol. The formation of the complex blocked the reactivity of iron and permitted its transport once introduced into circulation in vivo. Scn-Ngal then recycled its iron in endosomes by a pH-sensitive mechanism. As catechols derive from bacterial and mammalian metabolism of dietary compounds, the Scn-Ngal-catechol-Fe(III) complex represents an unforeseen microbial-host interaction, which mimics Scn-Ngal-siderophore interactions but instead traffics iron in aseptic tissues. These results identify an endogenous siderophore, which may link the disparate roles of Scn-Ngal in different diseases.
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143
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Hohlbaum AM, Skerra A. Anticalins: the lipocalin family as a novel protein scaffold for the development of next-generation immunotherapies. Expert Rev Clin Immunol 2010; 3:491-501. [PMID: 20477155 DOI: 10.1586/1744666x.3.4.491] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Anticalins are engineered ligand-binding proteins based on the human lipocalin scaffold. Their architecture is characterized by a rigid beta-barrel that supports four structurally hypervariable loops. Similar to antibodies, these loops form the natural ligand-binding site, usually for vitamins, hormones or secondary metabolites. Anticalins with novel specificities can be engineered by reshaping this loop region, using targeted random mutagenesis in combination with functional display and guided selection. Several drug candidates with specificities for exogenous low-molecular-weight substances, peptides and even protein targets (e.g., several disease-related cell surface receptors) have been obtained in this way. Owing to their exquisite specificity and high affinity, Anticalins are particularly attractive as antagonists for the manipulation of immune mechanisms, leading to either inhibitory or stimulatory effects. Compared with antibodies, Anticalins offer several practical advantages as they are much smaller, consist of a single polypeptide chain and can be produced easily in microbial expression systems.
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144
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Abstract
Siderophores are compounds produced by bacteria, fungi and graminaceous plants for scavenging iron from the environment. They are low-molecular-weight compounds (500-1500 daltons) possessing a high affinity for iron(III) (Kf > 1030), the biosynthesis of which is regulated by iron levels and the function of which is to supply iron to the cell. This article briefly describes the classification and chemical properties of siderophores, before outlining research on siderophore biosynthesis and transport. Clinically important siderophores and the therapeutic potential of siderophore design are described. Appendix 1 provides a comprehensive list of siderophore structures.
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Affiliation(s)
- Robert C Hider
- Division of Pharmaceutical Science, King's College, London, SE1 9NH, UK.
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145
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Madhurantakam C, Nilsson OB, Uchtenhagen H, Konradsen J, Saarne T, Högbom E, Sandalova T, Grönlund H, Achour A. Crystal structure of the dog lipocalin allergen Can f 2: implications for cross-reactivity to the cat allergen Fel d 4. J Mol Biol 2010; 401:68-83. [PMID: 20621650 DOI: 10.1016/j.jmb.2010.05.043] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 05/17/2010] [Accepted: 05/18/2010] [Indexed: 12/25/2022]
Abstract
The dog lipocalin allergen Can f 2 is an important cause of allergic sensitization in humans worldwide. Here, the first crystal structure of recombinant rCan f 2 at 1.45 A resolution displays a classical lipocalin fold with a conserved Gly-Xaa-Trp motif, in which Trp19 stabilizes the overall topology of the monomeric rCan f 2. Phe38 and Tyr84 localized on the L1 and L5 loops, respectively, control access to the highly hydrophobic calyx. Although the rCan f 2 calyx is nearly identical with the aero-allergens MUP1, Equ c 1 and A2U from mouse, horse and rat, respectively, no IgE cross-reactivity was found using sera from five mono-sensitized subjects. However, clear IgE cross-reactivity was demonstrated between Can f 2 and the cat allergen Fel d 4, although they share less than 22% sequence identity. This suggests a role for these allergens in co-sensitization between cat- and dog-allergic patients.
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Affiliation(s)
- Chaithanya Madhurantakam
- Centre for Infectious Medicine, F59, Department of Medicine Huddinge, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden
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146
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Halaas O, Steigedal M, Haug M, Awuh JA, Ryan L, Brech A, Sato S, Husebye H, Cangelosi GA, Akira S, Strong RK, Espevik T, Flo TH. Intracellular Mycobacterium avium intersect transferrin in the Rab11(+) recycling endocytic pathway and avoid lipocalin 2 trafficking to the lysosomal pathway. J Infect Dis 2010; 201:783-92. [PMID: 20121435 DOI: 10.1086/650493] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Iron is an essential nutrient for microbes, and many pathogenic bacteria depend on siderophores to obtain iron. The mammalian innate immunity protein lipocalin 2 (Lcn2; also known as neutrophil gelatinase-associated lipocalin, 24p3, or siderocalin) binds the siderophore carboxymycobactin, an essential component of the iron acquisition apparatus of mycobacteria. Here we show that Lcn2 suppressed growth of Mycobacterium avium in culture, and M. avium induced Lcn2 production from mouse macrophages. Lcn2 also had elevated levels and initially limited the growth of M. avium in the blood of infected mice but did not impede growth in tissues and during long-term infections. M. avium is an intracellular pathogen. Subcellular imaging of infected macrophages revealed that Lcn2 trafficked to lysosomes separate from M. avium, whereas transferrin was efficiently transported to the mycobacteria. Thus, mycobacteria seem to reside in the Rab11(+) endocytic recycling pathway, thereby retaining access to nutrition and avoiding endocytosed immunoproteins like Lcn2.
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Affiliation(s)
- Oyvind Halaas
- Department of Cancer Research and Molecular Medicine, Norges Teknisk-Naturvitenskapelige Universitet, and St. Olavs Hospital, Trondheim, Norway
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147
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Olejniczak ET, Ruan Q, Ziemann RN, Birkenmeyer LG, Saldana SC, Tetin SY. Rapid determination of antigenic epitopes in human NGAL using NMR. Biopolymers 2010; 93:657-67. [DOI: 10.1002/bip.21417] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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148
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Grigg JC, Cooper JD, Cheung J, Heinrichs DE, Murphy MEP. The Staphylococcus aureus siderophore receptor HtsA undergoes localized conformational changes to enclose staphyloferrin A in an arginine-rich binding pocket. J Biol Chem 2010; 285:11162-71. [PMID: 20147287 DOI: 10.1074/jbc.m109.097865] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus uses several efficient iron acquisition strategies to overcome iron limitation. Recently, the genetic locus encoding biosynthetic enzymes for the iron chelating molecule, staphyloferrin A (SA), was determined. S. aureus synthesizes and secretes SA into its environment to scavenge iron. The membrane-anchored ATP binding cassette-binding protein, HtsA, receives the ferric-chelate for import into the cell. Recently, we determined the apoHtsA crystal structure, the first siderophore receptor from gram-positive bacteria to be structurally characterized. Herein we present the x-ray crystal structure of the HtsA-ferric-SA complex. HtsA adopts a class III binding protein fold composed of separate N- and C-terminal domains bridged by a single alpha-helix. Recombinant HtsA can efficiently sequester ferric-SA from S. aureus culture supernatants where it is bound within the pocket formed between distinct N- and C-terminal domains. A basic patch composed mainly of six Arg residues contact the negatively charged siderophore, securing it within the pocket. The x-ray crystal structures from two different ligand-bound crystal forms were determined. The structures represent the first structural characterization of an endogenous alpha-hydroxycarboxylate-type siderophore-receptor complex. One structure is in an open form similar to apoHtsA, whereas the other is in a more closed conformation. The conformational change is highlighted by isolated movement of three loops within the C-terminal domain, a domain movement unique to known class III binding protein structures.
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Affiliation(s)
- Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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149
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Sivick KE, Mobley HLT. Waging war against uropathogenic Escherichia coli: winning back the urinary tract. Infect Immun 2010; 78:568-85. [PMID: 19917708 PMCID: PMC2812207 DOI: 10.1128/iai.01000-09] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is a substantial economic and societal burden-a formidable public health issue. Symptomatic UTI causes significant discomfort in infected patients, results in lost productivity, predisposes individuals to more serious infections, and usually necessitates antibiotic therapy. There is no licensed vaccine available for prevention of UTI in humans in the United States, likely due to the challenge of targeting a relatively heterogeneous group of pathogenic strains in a unique physiological niche. Despite significant advances in the understanding of UPEC biology, mechanistic details regarding the host response to UTI and full comprehension of genetic loci that influence susceptibility require additional work. Currently, there is an appreciation for the role of classic innate immune responses-from pattern receptor recognition to recruitment of phagocytic cells-that occur during UPEC-mediated UTI. There is, however, a clear disconnect regarding how factors involved in the innate immune response to UPEC stimulate acquired immunity that facilitates enhanced clearance upon reinfection. Unraveling the molecular details of this process is vital in the development of a successful vaccine for prevention of human UTI. Here, we survey the current understanding of host responses to UPEC-mediated UTI with an eye on molecular and cellular factors whose activity may be harnessed by a vaccine that stimulates lasting and sterilizing immunity.
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Affiliation(s)
- Kelsey E. Sivick
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Harry L. T. Mobley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
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150
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Johnson EE, Srikanth CV, Sandgren A, Harrington L, Trebicka E, Wang L, Borregaard N, Murray M, Cherayil BJ. Siderocalin inhibits the intracellular replication of Mycobacterium tuberculosis in macrophages. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 2010; 58:138-45. [PMID: 19863663 PMCID: PMC2822896 DOI: 10.1111/j.1574-695x.2009.00622.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Siderocalin is a secreted protein that binds to siderophores to prevent bacterial iron acquisition. While it has been shown to inhibit the growth of Mycobacterium tuberculosis (M.tb) in extracellular cultures, its effect on this pathogen within macrophages is not clear. Here, we show that siderocalin expression is upregulated following M.tb infection of mouse macrophage cell lines and primary murine alveolar macrophages. Furthermore, siderocalin added exogenously as a recombinant protein or overexpressed in the RAW264.7 macrophage cell line inhibited the intracellular growth of the pathogen. A variant form of siderocalin, which is expressed only in the macrophage cytosol, inhibited intracellular M.tb growth as effectively as the normal, secreted form, an observation that provides mechanistic insight into how siderocalin might influence iron acquisition by the bacteria in the phagosome. Our findings are consistent with an important role for siderocalin in protection against M.tb infection and suggest that exogenously administered siderocalin may have therapeutic applications in tuberculosis.
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Affiliation(s)
- Erin E. Johnson
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Chittur V. Srikanth
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Andreas Sandgren
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
| | - Lynne Harrington
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Estela Trebicka
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Lijian Wang
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Charlestown, MA 02129, USA
- Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA
| | - Niels Borregaard
- Department of Hematology, University of Copenhagen, Copenhagen, Denmark
| | - Megan Murray
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
| | - Bobby J. Cherayil
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Charlestown, MA 02129, USA
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