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O'Rourke F, Kempf VAJ. Interaction of bacteria and stem cells in health and disease. FEMS Microbiol Rev 2019; 43:162-180. [DOI: 10.1093/femsre/fuz003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/11/2019] [Indexed: 12/11/2022] Open
Affiliation(s)
- Fiona O'Rourke
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, University Hospital, Goethe University, Paul-Ehrlich-Str. 40, D-60596 Frankfurt am Main, Germany
| | - Volkhard A J Kempf
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, University Hospital, Goethe University, Paul-Ehrlich-Str. 40, D-60596 Frankfurt am Main, Germany
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Differential Susceptibility of Male Versus Female Laboratory Mice to Anaplasma phagocytophilum Infection. Trop Med Infect Dis 2018; 3:tropicalmed3030078. [PMID: 30274474 PMCID: PMC6161277 DOI: 10.3390/tropicalmed3030078] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/07/2018] [Accepted: 07/18/2018] [Indexed: 12/20/2022] Open
Abstract
Human granulocytic anaplasmosis (HGA) is a debilitating, non-specific febrile illness caused by the granulocytotropic obligate intracellular bacterium called Anaplasma phagocytophilum. Surveillance studies indicate a higher prevalence of HGA in male versus female patients. Whether this discrepancy correlates with differential susceptibility of males and females to A. phagocytophilum infection is unknown. Laboratory mice have long been used to study granulocytic anaplasmosis. Yet, sex as a biological variable (SABV) in this model has not been evaluated. In this paper, groups of male and female C57Bl/6 mice that had been infected with A. phagocytophilum were assessed for the bacterial DNA load in the peripheral blood, the percentage of neutrophils harboring bacterial inclusions called morulae, and splenomegaly. Infected male mice exhibited as much as a 1.85-fold increase in the number of infected neutrophils, which is up to a 1.88-fold increase in the A. phagocytophilum DNA load, and a significant increase in spleen size when compared to infected female mice. The propensity of male mice to develop a higher level of A. phagocytophilum infection is relevant for studies utilizing the mouse model. This stresses the importance of including SABV and aligns with the observed higher incidence of infection in male versus female patients.
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Cangussu ASR, Mariúba LAM, Lalwani P, Pereira KDES, Astolphi-Filho S, Orlandi PP, Epiphanio S, Viana KF, Ribeiro MFB, Silva HM, Marinho CRF, Nogueira PA. A hybrid protein containing MSP1a repeats and Omp7, Omp8 and Omp9 epitopes protect immunized BALB/c mice against anaplasmosis. Vet Res 2018; 49:6. [PMID: 29351812 PMCID: PMC5775529 DOI: 10.1186/s13567-018-0503-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 12/20/2017] [Indexed: 12/23/2022] Open
Abstract
Anaplasma marginale (A. marginale) has a remarkable impact on livestock production, and an effective vaccine is not currently available due to the inexistence of a small animal model. Recently, BALB/c mice were successfully infected with A. marginale, resulting in an acute and persistent anaplasmosis infection. Here, we designed a hybrid protein containing repeats of polypeptide 1a from major surface protein-1 complex (MSP1a) repeats and common epitopes of outer membrane proteins (OMPs) OMP7, OMP8 and OMP9 expressed in Escherichia coli. Our proof-of-concept assessed vaccinal effectiveness against a challenge with live bacteria. The MSP1a/OMP7/8/9 immunized BALB/C mice exhibited a strong reduction in rickettsemia and had no signs of anaplasmosis or hepatic lesions. In contrast, the non-immunized mice exhibited signs of anaplasmosis and a body weight loss associated with increases in monocyte and neutrophil counts. Furthermore, the non-immunized mice displayed atrophies with chronic inflammatory infiltrates in the spleen and increased binucleation and hydropic degeneration in the hepatocytes. Our findings demonstrated that immunization with our hybrid protein induced a strong reduction in rickettsemia and conferred protection against anaplasmosis. Therefore, given the strong evidence of the protective effect against anaplasmosis, hybrid protein designs are potential candidates for the rational design of vaccinal subunits.
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Affiliation(s)
- Alex Sander R Cangussu
- Universidade Federal do Amazonas-Programa de pós-graduação em Rede de Biodiversidade e Biotecnologia da Amazônia Legal, Manaus, AM/Brasil, Brazil. .,Universidade Federal do Tocantins-Engenharia de Bioprocessos e Biotecnologia, Gurupi, TO/Brazil, Brazil.
| | - Luis André M Mariúba
- Instituto Leônidas e Maria Deane-Fiocruz Amazônia, Manaus, Amazonas/Brazil, Brazil
| | - Pritesh Lalwani
- Instituto Leônidas e Maria Deane-Fiocruz Amazônia, Manaus, Amazonas/Brazil, Brazil
| | | | - Spartaco Astolphi-Filho
- Universidade Federal do Amazonas-Programa de pós-graduação em Rede de Biodiversidade e Biotecnologia da Amazônia Legal, Manaus, AM/Brasil, Brazil
| | - Patricia P Orlandi
- Instituto Leônidas e Maria Deane-Fiocruz Amazônia, Manaus, Amazonas/Brazil, Brazil
| | - Sabrina Epiphanio
- Departamento de Análises Clínicas e Toxicológicas da Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, São Paulo/Brazil, Brazil
| | - Kelvison F Viana
- Universidade Federal do Tocantins-Engenharia de Bioprocessos e Biotecnologia, Gurupi, TO/Brazil, Brazil
| | - Mucio Flavio B Ribeiro
- Departamento de Parasitologia do Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais/Brazil, Brazil
| | - Hidelberto M Silva
- Faculdade de Medicina, Centro Universitário Unirg, Gurupi, Tocantins/Brazil, Brazil
| | - Claudio R F Marinho
- Departamento de Parasitologia do Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Paulo A Nogueira
- Instituto Leônidas e Maria Deane-Fiocruz Amazônia, Manaus, Amazonas/Brazil, Brazil
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Hodzic E. Lyme Borreliosis: Is there a preexisting (natural) variation in antimicrobial susceptibility among Borrelia burgdorferi strains? Bosn J Basic Med Sci 2015; 15:1-13. [PMID: 26295288 DOI: 10.17305/bjbms.2015.594] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 06/29/2015] [Accepted: 06/30/2015] [Indexed: 12/31/2022] Open
Abstract
The development of antibiotics changed the world of medicine and has saved countless human and animal lives. Bacterial resistance/tolerance to antibiotics have spread silently across the world and has emerged as a major public health concern. The recent emergence of pan-resistant bacteria can overcome virtually any antibiotic and poses a major problem for their successful control. Selection for antibiotic resistance may take place where an antibiotic is present: in the skin, gut, and other tissues of humans and animals and in the environment. Borrelia burgdorferi, the etiological agents of Lyme borreliosis, evades host immunity and establishes persistent infections in its mammalian hosts. The persistent infection poses a challenge to the effective antibiotic treatment, as demonstrated in various animal models. An increasingly heterogeneous subpopulation of replicatively attenuated spirochetes arises following treatment, and these persistent antimicrobial tolerant/resistant spirochetes are non-cultivable. The non-cultivable spirochetes resurge in multiple tissues at 12 months after treatment, with B. burgdorferi-specific DNA copy levels nearly equivalent to those found in shame-treated experimental animals. These attenuated spirochetes remain viable, but divide slowly, thereby being tolerant to antibiotics. Despite the continued non-cultivable state, RNA transcription of multiple B. burgdorferi genes was detected in host tissues, spirochetes were acquired by xenodiagnostic ticks, and spirochetal forms could be visualized within ticks and mouse tissues. A number of host cytokines were up- or down-regulated in tissues of both shame- and antibiotic-treated mice in the absence of histopathology, indicating a lack of host response to the presence of antimicrobial tolerant/resistant spirochetes.
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Affiliation(s)
- Emir Hodzic
- Real-Time PCR Research & Diagnostics Core Facility, School of Veterinary Medicine, University of California, Davis.
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5
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Zhao X, Bu DX, Hayfron K, Pinkerton KE, Bevins CL, Lichtman A, Wiedeman J. A combination of secondhand cigarette smoke and Chlamydia pneumoniae accelerates atherosclerosis. Atherosclerosis 2012; 222:59-66. [DOI: 10.1016/j.atherosclerosis.2012.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 01/18/2012] [Accepted: 02/02/2012] [Indexed: 10/28/2022]
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Johns JL, Borjesson DL. Downregulation of CXCL12 signaling and altered hematopoietic stem and progenitor cell trafficking in a murine model of acute Anaplasma phagocytophilum infection. Innate Immun 2011; 18:418-28. [PMID: 21964802 DOI: 10.1177/1753425911413794] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Infection with a variety of bacterial pathogens results in hematopoietic stem and progenitor cell (HSPC) mobilization. The mechanism and kinetics of HSPC mobilization during infection are largely unknown. Previously, we found altered HSPC activity in bone marrow, spleen and blood during infection with Anaplasma phagocytophilum, the agent of granulocytic anaplasmosis. We hypothesized that altered CXCL12/CXCR4 signaling, a central pathway for HSPC homing to, and retention within, the bone marrow, plays a role in infection-induced alterations in HSPC number and trafficking. Mice were infected with A. phagocytophilum. Lineage-cKit+ HSPCs were enumerated and proliferation determined. CXCL12 and CXCR4 mRNA were quantified along with CXCL12 protein, and CXCR4 surface, intracellular and total protein expression in HSPCs was determined. Increased bone marrow proliferation of HSPCs began at 2 d post-infection followed by HSPC mobilization and splenic homing. Proliferation of resident HSPCs contributed to increased splenic HSPC numbers. Bone marrow CXCL12 mRNA and protein levels were decreased at 4-8 d post-infection concurrent with HSPC mobilization. CXCR4 protein parameters were decreased in bone marrow HSPCs throughout 2-6 d post-infection. Reduction of CXCL12/CXCR4 signaling simultaneously occurs with HSPC mobilization from bone marrow. Findings suggest that deranged CXCL12/CXCR4 signaling plays a causal role in HSPC mobilization during acute A. phagocytophilum infection.
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Affiliation(s)
- J L Johns
- Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Dexamethasone-induced cytokine changes associated with diminished disease severity in horses infected with Anaplasma phagocytophilum. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:1962-8. [PMID: 21880854 DOI: 10.1128/cvi.05034-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Anaplasma phagocytophilum is the zoonotic cause of granulocytic anaplasmosis. We hypothesized that immune response, specifically gamma interferon (IFN-γ), plays a role in disease severity. To test this, horses were infected and IFNG expression was pharmacologically downregulated using corticosteroids. Eight horses were infected with A. phagocytophilum; 4 received dexamethasone on days 4 to 8 of infection. Clinical signs, hematologic parameters, and transcription of cytokine/chemokine genes were compared among treated and untreated horses. Infection was quantitated by msp2 real-time PCR and microscopy. As anticipated, there was significantly greater leukopenia, thrombocytopenia, and anemia in infected versus uninfected horses. The A. phagocytophilum load was higher for dexamethasone-treated horses. Dexamethasone reduced IFNG transcription by day 12 and IL-8 and IL-18 by days 7 to 9 and increased IL-4 on day 7. The ratio of IL-10 to IFNG was increased by dexamethasone on day 9. There were no hematologic differences between the infected horses. Dexamethasone suppression of proinflammatory response resulted in delayed infection-induced limb edema and decreased icterus, anorexia, and reluctance to move between days 6 and 9 and lower fever on day 7. These results underscore the utility of the equine model of granulocytic anaplasmosis and suggest that Th1 proinflammatory response plays a role in worsening disease severity and that disease severity can be decreased by modulating proinflammatory response. A role for Th1 response and macrophage activation in hematologic derangements elicited by A. phagocytophilum is not supported by these data and remains unproven.
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Mechanisms of obligatory intracellular infection with Anaplasma phagocytophilum. Clin Microbiol Rev 2011; 24:469-89. [PMID: 21734244 PMCID: PMC3131063 DOI: 10.1128/cmr.00064-10] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Anaplasma phagocytophilum persists in nature by cycling between mammals and ticks. Human infection by the bite of an infected tick leads to a potentially fatal emerging disease called human granulocytic anaplasmosis. A. phagocytophilum is an obligatory intracellular bacterium that replicates inside mammalian granulocytes and the salivary gland and midgut cells of ticks. A. phagocytophilum evolved the remarkable ability to hijack the regulatory system of host cells. A. phagocytophilum alters vesicular traffic to create an intracellular membrane-bound compartment that allows replication in seclusion from lysosomes. The bacterium downregulates or actively inhibits a number of innate immune responses of mammalian host cells, and it upregulates cellular cholesterol uptake to acquire cholesterol for survival. It also upregulates several genes critical for the infection of ticks, and it prolongs tick survival at freezing temperatures. Several host factors that exacerbate infection have been identified, including interleukin-8 (IL-8) and cholesterol. Host factors that overcome infection include IL-12 and gamma interferon (IFN-γ). Two bacterial type IV secretion effectors and several bacterial proteins that associate with inclusion membranes have been identified. An understanding of the molecular mechanisms underlying A. phagocytophilum infection will foster the development of creative ideas to prevent or treat this emerging tick-borne disease.
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Schaff UY, Trott KA, Chase S, Tam K, Johns JL, Carlyon JA, Genetos DC, Walker NJ, Simon SI, Borjesson DL. Neutrophils exposed to A. phagocytophilum under shear stress fail to fully activate, polarize, and transmigrate across inflamed endothelium. Am J Physiol Cell Physiol 2010; 299:C87-96. [PMID: 20392928 PMCID: PMC2904253 DOI: 10.1152/ajpcell.00165.2009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Accepted: 04/02/2010] [Indexed: 11/22/2022]
Abstract
Anaplasma phagocytophilum is an obligate intracellular bacterium that has evolved mechanisms to hijack polymorphonuclear neutrophil (PMN) receptors and signaling pathways to bind, infect, and multiply within the host cell. E-selectin is upregulated during inflammation and is a requisite endothelial receptor that supports PMN capture, rolling, and activation of integrin-mediated arrest. Ligands expressed by PMN that mediate binding to endothelium via E-selectin include sialyl Lewis x (sLe(x))-expressing ligands such as P-selectin glycoprotein ligand-1 (PSGL-1) and other glycolipids and glycoproteins. As A. phagocytophilum is capable of binding to sLe(x)-expressing ligands expressed on PMN, we hypothesized that acute bacterial adhesion to PMN would subsequently attenuate PMN recruitment during inflammation. We assessed the dynamics of PMN recruitment and migration under shear flow in the presence of a wild-type strain of A. phagocytophilum and compared it with a strain of bacteria that binds to PMN independent of PSGL-1. Acute bacterial engagement with PMN resulted in transient PMN arrest and minimal PMN polarization. Although the wild-type pathogen also signaled activation of beta2 integrins and elicited a mild intracellular calcium flux, downstream signals including PMN transmigration and phosphorylation of p38 mitogen-activated protein kinase (MAPK) were inhibited. The mutant strain bound less well to PMN and failed to activate beta2 integrins and induce a calcium flux but did result in decreased PMN arrest and polarization that may have been partially mediated by a suppression of p38 MAPK activation. This model suggests that A. phagocytophilum binding to PMN under shear flow during recruitment to inflamed endothelium interferes with normal tethering via E-selectin and navigational signaling of transendothelial migration.
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Affiliation(s)
- U Y Schaff
- Department of Biomedical Engineering, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Stuen S, Torsteinbø WO, Bergström K, Bårdsen K. Superinfection occurs in Anaplasma phagocytophilum infected sheep irrespective of infection phase and protection status. Acta Vet Scand 2009; 51:41. [PMID: 19857248 PMCID: PMC2772837 DOI: 10.1186/1751-0147-51-41] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Accepted: 10/26/2009] [Indexed: 12/03/2022] Open
Abstract
Background Anaplasma phagocytophilum infection in domestic ruminants is widespread in the coastal areas of southern Norway. The bacteria may persist in mammalian hosts. Several genetic variants of A. phagocytophilum exist. In the present study, we investigate whether superinfection occurs in the acute and persistent phase of the infection. Methods Five-month-old lambs of the Norwegian Dala breed were experimentally infected with two 16S rRNA gene variants of A. phagocytophilum, i.e. A. phagocytophilum variant 1 (GenBank accession number M73220) and variant 2 (GenBank acc. no. AF336220). Eighteen lambs were used, two lambs in each group. Eight groups were experimentally inoculated with either variant 1 or 2 on day 0. Six of these groups were then challenged with the other variant on either days 7, 42 or 84, respectively. One group was left uninfected. The occurrence of A. phagocytophilum in blood samples was determined using semi-nested PCR analysis and gene sequencing. Specific antibodies were measured by an indirect immunofluorescence antibody assay (IFA). Results A. phagocytophilum variant 1 and 2 differed significantly with regards to clinical reaction and cross-immunity in infected lambs. Both variants were found in the blood after challenge. However, variant 1 was detected most frequently. Conclusion The present experiment indicates that superinfection of different genotypes occurs during the acute as well as the persistent phase of an A. phagocytophilum infection, even in lambs protected against the challenged infection.
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Infection with Anaplasma phagocytophilum induces multilineage alterations in hematopoietic progenitor cells and peripheral blood cells. Infect Immun 2009; 77:4070-80. [PMID: 19564373 DOI: 10.1128/iai.00570-09] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Infection with Anaplasma phagocytophilum, a gram-negative, lipopolysaccharide (LPS)-negative, obligate intracellular bacterium, results in multiple peripheral blood cytopenias. We hypothesized that infection with this organism would result in decreased bone marrow (BM) function and shifts in hematopoietic progenitor cells (HPCs) and lineage-committed cells in a well-established murine model of infection. HPCs and lineage-committed progenitors were enumerated in the BM and spleen during acute infection. BM cytokine production and BM CXCL12 expression were determined. Infection resulted in peripheral blood bicytopenia, marked decreases in the number of lineage-committed HPCs in the BM along with concurrent increases in the number of lineage-committed HPCs in the spleen, and a mixed, predominantly myelosuppressive BM cytokine environment. There was significant downregulation of CXCL12 in BM cells that may have been partially responsible for changes in HPC trafficking observed. Changes occurred in the absence of direct pathogen infection of BM cells. Hematopoietic lineage assessment demonstrated that there was loss of erythrocytes and B lymphocytes from the BM along with increased granulopoiesis. These changes were accompanied by splenomegaly due to lymphoid hyperplasia and increased hematopoiesis, most notably erythropoiesis. These changes largely mimic well-described inflammation and endotoxin-mediated effects on the BM and spleen; however, the numbers of peripheral blood neutrophils appear to be independently modulated as granulocytic hyperplasia does not result in neutrophilia. Our findings highlight a well-conserved series of events that we demonstrate can be instigated by an LPS-negative pathogen in the absence of an endotoxin-mediated acute proinflammatory response.
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Granick JL, Reneer DV, Carlyon JA, Borjesson DL. Anaplasma phagocytophilum infects cells of the megakaryocytic lineage through sialylated ligands but fails to alter platelet production. J Med Microbiol 2008; 57:416-423. [PMID: 18349358 DOI: 10.1099/jmm.0.47551-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Anaplasma phagocytophilum is an obligate intracellular bacterial pathogen that principally inhabits neutrophils. However, infection with A. phagocytophilum results in a moderate to marked thrombocytopenia. In host neutrophils, A. phagocytophilum uses sialylated ligands, primarily P-selectin glycoprotein ligand-1 (PSGL-1), to enter its host cell. PSGL-1 is expressed on a wide array of haematopoietic cells, including megakaryocytes. In this study, it was hypothesized that (i) cells of the megakaryocytic lineage (MEG-01 cells) would be susceptible to A. phagocytophilum infection and (ii) infection may induce alterations in platelet production contributing to infection-induced thrombocytopenia. It was found that MEG-01 cells are susceptible to infection. MEG-01 cells expressing abundant sialylated ligands were the most susceptible to infection, and the absence of sialylation, or blocking of PSGL-1, limited infection susceptibility. However, infected MEG-01 cells produced proplatelets and platelet-like particles comparable to uninfected cells. These results highlight a novel target of pathogen infection and suggest that the pathogen may utilize similar strategies to gain access to megakaryocytes. Direct pathogen modification of platelet production may not play a role in infection-induced thrombocytopenia.
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Affiliation(s)
- Jennifer L Granick
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN, USA
| | - Dexter V Reneer
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KT, USA
| | - Jason A Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Dori L Borjesson
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, Davis, CA, USA
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Pedra JHF, Sutterwala FS, Sukumaran B, Ogura Y, Qian F, Montgomery RR, Flavell RA, Fikrig E. ASC/PYCARD and caspase-1 regulate the IL-18/IFN-gamma axis during Anaplasma phagocytophilum infection. THE JOURNAL OF IMMUNOLOGY 2007; 179:4783-91. [PMID: 17878377 DOI: 10.4049/jimmunol.179.7.4783] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Anaplasma phagocytophilum is an obligate intracellular pathogen that resides within neutrophils and can cause fever, pancytopenia, or death. IFN-gamma plays a critical role in the control of A. phagocytophilum; however, the mechanisms that regulate IFN-gamma production remain unclear. In this study, we demonstrate that apoptotic specklike protein with a caspase-activating recruiting domain (ASC)/PYCARD, a central adaptor molecule in the Nod-like receptor (NLR) pathway, regulates the IL-18/IFN-gamma axis during A. phagocytophilum infection through its effect on caspase-1. Caspase-1- and asc-null mice were more susceptible than control animals to A. phagocytophilum infection due to the absence of IL-18 secretion and reduced IFN-gamma levels in the peripheral blood. Moreover, caspase-1 and ASC deficiency reduced CD4+ T cell-mediated IFN-gamma after in vitro restimulation with A. phagocytophilum. The NLR family member IPAF/NLRC4, but not NALP3/NLRP3, was partially required for IFN-gamma production in response to A. phagocytophilum. Taken together, our data demonstrate that ASC and caspase-1 are critical for IFN-gamma-mediated control of A. phagocytophilum infection.
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Affiliation(s)
- Joao H F Pedra
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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Pedra JHF, Tao J, Sutterwala FS, Sukumaran B, Berliner N, Bockenstedt LK, Flavell RA, Yin Z, Fikrig E. IL-12/23p40-dependent clearance of Anaplasma phagocytophilum in the murine model of human anaplasmosis. ACTA ACUST UNITED AC 2007; 50:401-10. [PMID: 17521390 DOI: 10.1111/j.1574-695x.2007.00270.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human anaplasmosis is an emerging infectious disease transmitted by ticks that can be potentially fatal in the immunocompromised and the elderly. The mechanisms of defense against the causative agent, Anaplasma phagocytophilum, are not completely understood; however, interferon (IFN)-gamma plays an important role in pathogen clearance. Here, we show that IFN-gamma is regulated through an early IL-12/23p40-dependent mechanism. Interleukin (IL)-12/23p40 is regulated in macrophages and dendritic cells after activation by microbial agonists and cytokines and constitutes a subunit of IL-12 and IL-23. IL-12/23p40-deficient mice displayed an increased A. phagocytophilum burden, accelerated thrombocytopenia and increased neutrophil numbers in the spleen at day 6 postinfection. Infection of MyD88- and mitogen-activated kinase kinase 3 (MKK3)-deficient mice suggested that the early susceptibility due to IL-12/23p40 deficiency was not dependent on signaling through MyD88 or MKK3. The lack of IL-12/23p40 reduced IFN-gamma production in both CD4(+) and CD8(+) T cells although the effect was more pronounced in CD4(+) T cells. Our data suggest that the immune response against A. phagocytophilum is a multifactorial and cooperative process. The IL-12/23p40 subunit drives the CD4(+) Th1 immune response in the early phase of infection and IL-12/23p40-independent mechanisms ultimately contribute to pathogen elimination from the host.
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Affiliation(s)
- Joao H F Pedra
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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15
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Blas-Machado U, de la Fuente J, Blouin EF, Almazán C, Kocan KM, Mysore JV. Experimental infection of C3H/HeJ mice with the NY18 isolate of Anaplasma phagocytophilum. Vet Pathol 2007; 44:64-73. [PMID: 17197625 DOI: 10.1354/vp.44-1-64] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human granulocytic anaplasmosis (HGA), an emerging disease of public health concern in many areas of the world, is caused by Anaplasma phagocytophilum. Small animal models of A phagocytophilum in laboratory mice have been developed and used to study the pathogenesis of HGA. In this study, we characterized the pathologic changes in acute infection of C3H/HeJ mice experimentally infected with the NY18 isolate of A phagocytophilum. Although no clinical signs were noted, acute infection was associated with gross splenomegaly, microscopic inflammatory lesions in the lung and liver, hyperplastic lesions on the spleen, and clinical pathology abnormalities including neutropenia and monocytosis. This study emphasizes the use of well-defined animal models as a valuable tool for the study of A phagocytophilum infections.
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Affiliation(s)
- U Blas-Machado
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA.
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Leo M, Haque R, Kabir M, Roy S, Lahlou RM, Mondal D, Tannich E, Petri WA. Evaluation of Entamoeba histolytica antigen and antibody point-of-care tests for the rapid diagnosis of amebiasis. J Clin Microbiol 2006; 44:4569-71. [PMID: 17035498 PMCID: PMC1698410 DOI: 10.1128/jcm.01979-06] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Accepted: 09/29/2006] [Indexed: 11/20/2022] Open
Abstract
The bedside diagnosis of amebiasis could improve patient care. In Bangladesh and Vietnam, a novel and simple-to-use Entamoeba histolytica rapid antigen test had 97% sensitivity and 100% specificity compared to the results of a standard enzyme-linked immunosorbent assay antigen detection method, and a rapid antibody test had 89 to 100% sensitivity and 89 to 95% specificity.
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Affiliation(s)
- Megan Leo
- University of Virginia, P.O. Box 801340, Charlottesville, VA 22908-1340, USA
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17
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Tate CM, Mead DG, Luttrell MP, Howerth EW, Dugan VG, Munderloh UG, Davidson WR. Experimental infection of white-tailed deer with Anaplasma phagocytophilum, etiologic agent of human granulocytic anaplasmosis. J Clin Microbiol 2005; 43:3595-601. [PMID: 16081884 PMCID: PMC1233969 DOI: 10.1128/jcm.43.8.3595-3601.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Serologic and molecular evidence of Anaplasma phagocytophilum has been demonstrated in white-tailed deer (WTD; Odocoileus virginianus), and deer are an important host for the tick vector Ixodes scapularis. In this study, we describe experimental infection of WTD with A. phagocytophilum. We inoculated four WTD with a human isolate of A. phagocytophilum propagated in tick cells. Two additional deer served as negative controls. All inoculated deer developed antibodies (titers, > or =64) to A. phagocytophilum, as determined by an indirect fluorescent antibody test, between 14 and 24 days postinfection [p.i.]), and two deer maintained reciprocal titers of > or =64 through the end of the 66-day study. Although morulae were not observed in granulocytes and A. phagocytophilum was not reisolated via tick cell culture of blood, 16S reverse transcriptase nested PCR (RT-nPCR) results indicated that A. phagocytophilum circulated in peripheral blood of three deer through at least 17 days p.i. and was present in two deer at 38 days p.i. Femoral bone marrow from one deer was RT-nPCR positive for A. phagocytophilum at 66 days p.i. There was no indication of clinical disease. These data confirm that WTD are susceptible to infection with a human isolate of A. phagocytophilum and verify that WTD produce detectable antibodies upon exposure to the organism. Because adults are the predominant life stage of I. scapularis found on deer and because adult I. scapularis ticks do not transmit A. phagocytophilum transovarially, it is unlikely that WTD are a significant source of A. phagocytophilum for immature ticks even though deer have a high probability of natural infection. However, the susceptibility and immunologic response of WTD to A. phagocytophilum render them suitable candidates as natural sentinels for this zoonotic tick-borne organism.
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Affiliation(s)
- Cynthia M Tate
- Southeastern Cooperative Wildlife Disease Study, Wildlife Health Building, College of Veterinary Medicine, The University of Georgia, Athens, GA 30602-7393.
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18
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Massung RF, Priestley RA, Levin ML. Transmission Route Efficacy and Kinetics of AnaplasmaphagocytophilumInfection in the White-Footed Mouse,Peromyscus leucopus. Vector Borne Zoonotic Dis 2004; 4:310-8. [PMID: 15682514 DOI: 10.1089/vbz.2004.4.310] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Anaplasma phagocytophilum was used to infect Peromyscus leucopus mice by three routes of inoculation: infected tick infestation and intraperitoneal (IP) and subcutaneous (SQ) injection of infected tissue culture cells. A set of 12 mice were infected (four tick, four IP, and four SQ), and blood was drawn at 1, 3, 6, 9, 12, 15, 21, 28, 35, and 60 days post-infection and analyzed by use of a quantitative PCR assay to assess the level of infection. An additional set of 108 mice were infected (36 tick, 36 IP, 36 SQ) and euthanized at 1, 3, 6, 9, 12, 15, 21, 28, and 35 days post-infection (four mice/time point), and blood, spleen, bone marrow, and bladder tissue samples were analyzed. Tick infection generally produced the highest average levels of infection and peaked at 9 days post-infestation in blood, spleen, and bone marrow and at 6 days after infestation in the bladder. IP injection resulted in levels of infection that peaked on day 6 (spleen) or 12 (bladder, bone marrow, and blood). A. phagocytophilum injected SQ showed low levels of infection, and the day of peak infection varied. The average level of infection in the blood drawstressed mice was consistently higher and peaked earlier than infection in the non-stressed, euthanized mice. Xenodiagnosis was used to assay a third set of 12 mice (four tick, four IP, and four SQ) on days 7 and 14 post-infection and ticks fed on tick-infected mice showed the highest rate of PCR-positive test results at both time points (day 7, 22.2%; day 14, 17.3%). These data indicate that P. leucopus mice can be infected by tick infestation, IP injection, or SQ injection but that the kinetics and level of infection are quite variable among individual mice, may be influenced by the route of inoculation, and may be further altered by common laboratory procedures such as repeated collection of blood samples.
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Affiliation(s)
- Robert F Massung
- Viral and Rickettsial Zoonoses Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseaes, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
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19
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Bitsaktsis C, Huntington J, Winslow G. Production of IFN-gamma by CD4 T cells is essential for resolving ehrlichia infection. THE JOURNAL OF IMMUNOLOGY 2004; 172:6894-901. [PMID: 15153508 DOI: 10.4049/jimmunol.172.11.6894] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To address the role of cellular immunity during ehrlichia infection, we have used a newly described model of monocytic ehrlichiosis that results from infection of mice by an ehrlichia that was isolated from an Ixodes ovatus tick (Ixodes ovatus ehrlichia, IOE). Immunocompetent C57BL/6 and BALB/c mice exhibited a dose-dependent susceptibility to IOE infection. Mice infected with a high dose inoculum ( approximately 1000 organisms) exhibited pronounced thrombocytopenia, lymphopenia, anemia, and morbidity within 12 days postinfection. Infection was associated with bacterial colonization of a number of tissues. In contrast, mice infected with a low dose inoculum ( approximately 100 organisms) exhibited only transient disease and were able to resolve the infection. SCID mice were highly susceptible to low-dose infection, indicating that adaptive immunity was required. Resistance to sublethal challenge in both C57BL/6 and BALB/c mice was CD4-, but not CD8-, dependent and required IL-12p40-dependent cytokines, IFN-gamma, and TNF-alpha, but not IL-4. CD4 T cells purified from infected mice proliferated in vitro in response to IOE Ags. T cell proliferation was associated with production of IFN-gamma, and the production of this cytokine by CD4 T cells rescued IFN-gamma-deficient mice from fatal infection. Exogenous IFN-gamma was capable of inducing microbiocidal activity in infected macrophages. The data suggest that classical immune mechanisms involving CD4 cells and type 1 cytokines are responsible for macrophage activation and for elimination of this intracellular bacterial pathogen.
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20
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Abstract
Our laboratory has been investigating the mechanisms of host defense during Ehrlichia chaffeensis infection in the mouse. Although major roles are clearly played by T cells, we found that antibodies could also control infection in both normal and immunocompromised SCID mice, and could protect the latter from lethal infection. Antibodies are not generally effective during such intracellular infections, so we would like to understand exactly how antibodies can mediate immunity in this model. We have found that much of the humoral immune response is directed at the bacterial outer membrane proteins (OMPs), and that highly effective OMP antibodies (mostly IgG2a) exhibited picomolar affinities and very long binding half-lives. These antibodies, which could mediate bacterial clearance from tissues as early as 24 hours after administration, require host Fc receptors for their function(s). In contrast, we have failed to find any role for complement or reactive nitrogen intermediates, or for neutrophils, or for NK cells. One possible mechanism is that antibodies or immune complexes trigger microbiocidal activities in infected macrophages that lead to the elimination of bacteria residing inside host macrophages. Alternatively, it is proposed that antibodies opsonize bacteria exposed during intercellular transfer. This notion is supported by studies that have demonstrated the presence of bacteria in the extracellular milieu during infection, and suggests that our understanding of the behavior of the bacterium in the host may be key to our understanding of its susceptibility to antibody-mediated host defenses.
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Affiliation(s)
- Gary M Winslow
- Wadsworth Center, New York State Department of Health, P.O. Box 22002, Albany, NY 12201-2002, USA.
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21
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Hodzic E, Borjesson DL, Feng S, Barthold SW. Acquisition dynamics of Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis at the host-vector interface. Vector Borne Zoonotic Dis 2003; 1:149-58. [PMID: 12680352 DOI: 10.1089/153036601316977750] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The population dynamics of two cotransmitted tick-borne pathogens, Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis (aoHGE), were assessed at the skin-vector interface at intervals after tick attachment on infected mice. Quantitative real-time polymerase chain reaction targeting the B. burgdorferi flagellin gene revealed consistent decreases in spirochete numbers in skin at the sites of tick attachment compared with non-tick attachment sites. This phenomenon was found during early (2 weeks) and late (8 weeks) infection and at 24, 48, and 72 h after tick attachment. A nonspecific inflammatory stimulus, implantation of suture material, did not have this effect. In contrast to B. burgdorferi, copy numbers of an aoHGE p44 target gene target were significantly increased at the sites of tick attachment, compared with non-tick sites. The non-specific stimulus of suture material had the same effect on aoHGE recruitment as tick attachment in aoHGE infected mice. These results reinforce the concept that B. burgdorferi interfaces with its vector by virtue of its non-systemic dermatotropism, and not via systemic hematogenous acquisition. In contrast, results indicate that the aoHGE relies upon hematogenous acquisition. Thus, these two cotransmitted tick-borne pathogens utilize distinctly different means of vector acquisition.
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Affiliation(s)
- E Hodzic
- Center for Comparative Medicine, School of Medicine, University of California Davis, 95616, USA
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22
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Borjesson DL, Simon SI, Hodzic E, DeCock HEV, Ballantyne CM, Barthold SW. Roles of neutrophil beta 2 integrins in kinetics of bacteremia, extravasation, and tick acquisition of Anaplasma phagocytophila in mice. Blood 2003; 101:3257-64. [PMID: 12480703 DOI: 10.1182/blood-2002-04-1019] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tick saliva contains anti-inflammatory and immunosuppressive substances that facilitate blood feeding and enhance tick-vectored pathogen transmission, including Anaplasma phagocytophila an etiologic agent of granulocytic ehrlichiosis. As such, inflammation at a tick-feeding site is strikingly different than that typically observed at other sites of inflammation. Up-regulation of CD11b/CD18 occurs in host granulocytes following interaction or infection with A phagocytophila, and the absence of CD11b/CD18 results in early increases in bacteremia. We hypothesized that beta 2 integrin-dependent infection kinetics and leukocyte extravasation are important determinants of neutrophil trafficking to, and pathogen acquisition at, tick-feeding sites. A phagocytophila infection kinetics were evaluated in CD11a/CD18, CD11b/CD18, and CD18 knock-out mice using quantitative polymerase chain reaction (PCR) of blood, ticks, and skin biopsies in conjunction with histopathology. A marked increase in the rate of A phagocytophila infection of neutrophils and pathogen burden in blood followed tick feeding. Infection kinetics were modified by beta 2 integrin expression and systemic neutrophil counts. Significant neutrophil-pathogen trafficking was observed to both suture and tick sites. Despite the prominent role for beta 2 integrins in neutrophil arrest in flowing blood, successful pathogen acquisition by ticks occurred in the absence of beta 2 integrins. Establishment of feeding pools that rely less on leukocyte trafficking and more on small hemorrhages may explain the ready amplification of A phagocytophila DNA from ticks infested on CD11/CD18-deficient mouse strains.
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Affiliation(s)
- Dori L Borjesson
- Center for Comparative Medicine, Schools of Medicine Veterinary Medicine, University of California, Davis 95616, USA
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Carlyon JA, Chan WT, Galán J, Roos D, Fikrig E. Repression of rac2 mRNA expression by Anaplasma phagocytophila is essential to the inhibition of superoxide production and bacterial proliferation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:7009-18. [PMID: 12471136 DOI: 10.4049/jimmunol.169.12.7009] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Anaplasma phagocytophila, the etiologic agent of human granulocytic ehrlichiosis, is an emerging bacterial pathogen that invades neutrophils and can be cultivated in HL-60 cells. Infected neutrophils and HL-60 cells fail to produce superoxide anion (O(2)(-)), which is partially attributable to the fact that A. phagocytophila inhibits transcription of gp91(phox), an integral component of NADPH oxidase. cDNA microarray and RT-PCR analyses demonstrated that transcription of the gene encoding Rac2, a key component in NADPH oxidase activation, was down-regulated in infected HL-60 cells. Quantitative RT-PCR demonstrated that rac2 mRNA expression was reduced 7-fold in retinoic acid-differentiated HL-60 cells and 50-fold in neutrophils following A. phagocytophila infection. Rac2 protein expression was absent in infected HL-60 cells. Rac1 and Rac2 are interchangeable in their abilities to activate NADPH oxidase. HL-60 cells transfected to express myc-tagged rac1 and gp91(phox) from the CMV immediate early promoter maintained the ability to generate O(2)(-) 120 h postinfection. A. phagocytophila proliferation was severely inhibited in these cells. These results directly attribute the inhibition of rac2 and gp91(phox) transcription to the loss of NADPH oxidase activity in A. phagocytophila-infected cells and demonstrate its importance to bacterial intracellular survival.
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Affiliation(s)
- Jason A Carlyon
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8031, USA
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24
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Hodzic E, Feng S, Freet KJ, Borjesson DL, Barthold SW. Borrelia burgdorferi population kinetics and selected gene expression at the host-vector interface. Infect Immun 2002; 70:3382-8. [PMID: 12065476 PMCID: PMC128091 DOI: 10.1128/iai.70.7.3382-3388.2002] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By using real-time quantitative PCR, the population dynamics and gene transcription of Borrelia burgdorferi were examined in ticks and skin of mice during acquisition of the infection from mice by ticks and during transmission of the infection from ticks to mice. Population dynamics were determined by using a flaB DNA target. A quantitative analysis of flaB, ospA, ospC, dbpA, and arp transcription was also performed. The results revealed that both uninfected larval and nymphal Ixodes scapularis ticks acquired B. burgdorferi as early as 1 day after attachment and that the sizes of spirochete populations within ticks increased during feeding. In addition, all gene targets revealed that there was RNA transcription during feeding. Similar events occurred within infected nymphal ticks feeding on uninfected hosts. Transmission from infected nymphal ticks to mice could be detected within 1 day after attachment. Analysis of skin during the first 3 days after attachment of infected ticks revealed rising numbers of spirochetes but minimal gene transcription. In contrast, the skin of mice with established infections revealed static populations of spirochetes and active but stable transcription of flaB, ospC, dbpA, and arp. There were consistent reductions in the number of spirochetes in the skin at the tick attachment sites compared to the number of spirochetes in the skin at nontick sites, but there were no differences in gene expression between tick and nontick skin sites. Evidence of ospA transcription in skin could be found 1 day after tick attachment but not thereafter.
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Affiliation(s)
- Emir Hodzic
- Center for Comparative Medicine, School of Medicine, University of California at Davis, Davis, California 95616, USA
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25
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Borjesson DL, Simon SI, Hodzic E, Ballantyne CM, Barthold SW. Kinetics of CD11b/CD18 up-regulation during infection with the agent of human granulocytic ehrlichiosis in mice. J Transl Med 2002; 82:303-11. [PMID: 11896209 DOI: 10.1038/labinvest.3780424] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The agent of human granulocytic ehrlichiosis (aoHGE) is a tick-borne, obligate intracellular, granulocytotropic bacterium able to infect numerous host species. Given its unique niche and the leukopenia often noted with infection, we investigated the effect of acute aoHGE infection on neutrophil activation by evaluating surface expression of the beta 2 integrin CD11b/CD18 in a mouse model using FACS analysis. Infection resulted in neutrophil activation with up-regulation of CD11b/CD18 in multiple strains of mice, however, hematologic analysis showed no apparent role for CD11b/CD18 in mediating peripheral leukopenia. Because IFN-gamma is an important cytokine during granulocytic ehrlichiosis and is known to activate leukocytes, we investigated the potential role of IFN-gamma in CD11b/CD18 up-regulation. Neutrophils from IFN-gamma knock-out mice became activated during aoHGE infection, however, the kinetics of activation differed from wild-type mice. In addition, activation correlated directly with the presence of bacteria because neutrophils with large intracytoplasmic morula also expressed higher levels of CD11b/CD18. CD11b/CD18 seemed to be critical to early bacterial clearance and killing in vivo because infection of mice with targeted genetic disruption of CD11b/CD18 resulted in an initial increase in bacterial burden compared with wild-type mice. Similarly, in vitro culture of neutrophils from infected CD11b/CD18 knock-out mice resulted in a marked increase in bacterial proliferation compared with congenic controls. The data support crucial roles of CD11b/CD18 and IFN-gamma-mediated cell activation as mechanisms that limit bacterial replication.
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Affiliation(s)
- Dori L Borjesson
- Center for Comparative Medicine, School of Medicine, University of California, Davis, California 95616, USA
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