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Duggal S, Rawat S, Siddqui G, Vishwakarma P, Samal S, Banerjee A, Vrati S. Dengue virus infection in mice induces bone marrow myeloid cell differentiation and generates Ly6Glow immature neutrophils with modulated functions. J Leukoc Biol 2024; 115:130-148. [PMID: 37648666 DOI: 10.1093/jleuko/qiad099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/13/2023] [Accepted: 08/15/2023] [Indexed: 09/01/2023] Open
Abstract
While neutrophil activation during dengue virus infection is known, the effect of dengue virus infection on neutrophil biogenesis has not been studied. We demonstrate that dengue virus serotype 2 induces the differentiation of mice progenitor cells ex vivo toward the CD11b+Ly6C+Ly6G+ granulocyte population. We further observed an expansion of CD11b+Ly6CintLy6Glow myeloid cells in the bone marrow of dengue virus serotype 2-infected AG129 mice with low CXCR2 expression, implying an immature population. Additionally, dengue virus serotype 2 alone could induce the differentiation of promyelocyte cell line HL-60 into neutrophil-like cells, as evidenced by increased expression of CD10, CD66b, CD16, CD11b, and CD62L, corroborating the preferential shift toward neutrophil differentiation by dengue virus serotype 2 in the mouse model of dengue infection. The functional analysis showed that dengue virus serotype 2-induced neutrophil-like cells exhibited reduced phagocytic activity and enhanced NETosis, as evidenced by the increased production of myeloperoxidase, citrullinated histones, extracellular DNA, and superoxide. These neutrophil-like cells lose their ability to proliferate irreversibly and undergo arrest in the G0 to G1 phase of the cell cycle. Further studies show that myeloperoxidase-mediated signaling operating through the reactive oxygen species axis may be involved in dengue virus serotype 2-induced proliferation and differentiation of bone marrow cells as ABAH, a myeloperoxidase inhibitor, limits cell proliferation in vitro and ex vivo, affects the cell cycle, and reduces reactive oxygen species production. Additionally, myeloperoxidase inhibitor reduced NETosis and vascular leakage in dengue virus serotype 2-infected AG129 mice. Our study thus provides evidence that dengue virus serotype 2 can accelerate the differentiation of bone marrow progenitor cells into neutrophils through myeloperoxidase and modulate their functions.
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Affiliation(s)
- Shweta Duggal
- Laboratory of Virology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Surender Rawat
- Laboratory of Virology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Gazala Siddqui
- Influenza and Respiratory Virus Laboratory, Centre for Virus Research, Therapeutics and Vaccines, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Preeti Vishwakarma
- Influenza and Respiratory Virus Laboratory, Centre for Virus Research, Therapeutics and Vaccines, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Sweety Samal
- Influenza and Respiratory Virus Laboratory, Centre for Virus Research, Therapeutics and Vaccines, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Arup Banerjee
- Laboratory of Virology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway, Faridabad-121001, Haryana, India
| | - Sudhanshu Vrati
- Laboratory of Virology, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway, Faridabad-121001, Haryana, India
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Dumler JS, Lichay M, Chen WH, Rennoll-Bankert KE, Park JH. Anaplasma phagocytophilum Activates NF-κB Signaling via Redundant Pathways. Front Public Health 2020; 8:558283. [PMID: 33194960 PMCID: PMC7661751 DOI: 10.3389/fpubh.2020.558283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 09/22/2020] [Indexed: 11/28/2022] Open
Abstract
Anaplasma phagocytophilum subverts neutrophil function permitting intracellular survival, propagation and transmission. Sustained pro-inflammatory response, recruitment of new host cells for population expansion, and delayed apoptosis are associated with prolonged nuclear presence of NF-κB. We investigated NF-κB signaling and transcriptional activity with A. phagocytophilum infection using inhibitors of NF-κB signaling pathways, and through silencing of signaling pathway genes. How inhibitors or silencing affected A. phagocytophilum growth, inflammatory response (transcription of the κB-enhanced genes CXCL8 and MMP9), and NF-κB signaling pathway gene expression were tested. Among A. phagocytophilum-infected HL-60 cells, nuclear NF-κB p50, p65, and p52 were detected by immunoblots or iTRAQ proteomics. A. phagocytophilum growth was affected most by the IKKαβ inhibitor wedelolactone (reductions of 96 to 99%) as compared with SC-514 that selectively inhibits IKKβ, illustrating a role for the non-canonical pathway. Wedelolactone inhibited transcription of both CXCL8 (p = 0.001) and MMP9 (p = 0.002) in infected cells. Compared to uninfected THP-1 cells, A. phagocytophilum infection led to >2-fold down regulation of 64 of 92 NF-κB signaling pathway genes, and >2-fold increased expression in only 4. Wedelolactone and SC-514 reversed downregulation in all 64 and 45, respectively, of the genes down-regulated by infection, but decreased expression in 1 gene with SC-514 only. Silencing of 20 NF-κB signal pathway genes increased bacterial growth in 12 (IRAK1, MAP3K1, NFKB1B, MAP3K7, TICAM2, TLR3, TRADD, TRAF3, CHUK, IRAK2, LTBR, and MALT1). Most findings support canonical pathway activation; however, the presence of NFKB2 in infected cell nuclei, selective non-canonical pathway inhibitors that dampen CXCL8 and MMP9 transcription with infection, upregulation of non-canonical pathway target genes CCL13 and CCL19, enhanced bacterial growth with TRAF3 and LTBR silencing provide evidence for non-canonical pathway signaling. Whether this impacts distinct inflammatory processes that underlie disease, and whether and how A. phagocytophilum subverts NF-κB signaling via these pathways, need to be investigated.
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Affiliation(s)
- J Stephen Dumler
- Department of Pathology, F. Edward Hébert School of Medicine, Uniformed Services University for the Health Sciences, Bethesda, MD, United States.,Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Marguerite Lichay
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Wan-Hsin Chen
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Kristen E Rennoll-Bankert
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jin-Ho Park
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Neutrophil-induced ferroptosis promotes tumor necrosis in glioblastoma progression. Nat Commun 2020; 11:5424. [PMID: 33110073 PMCID: PMC7591536 DOI: 10.1038/s41467-020-19193-y] [Citation(s) in RCA: 206] [Impact Index Per Article: 51.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 10/02/2020] [Indexed: 12/16/2022] Open
Abstract
Tumor necrosis commonly exists and predicts poor prognoses in many cancers. Although it is thought to result from chronic ischemia, the underlying nature and mechanisms driving the involved cell death remain obscure. Here, we show that necrosis in glioblastoma (GBM) involves neutrophil-triggered ferroptosis. In a hyperactivated transcriptional coactivator with PDZ-binding motif-driven GBM mouse model, neutrophils coincide with necrosis temporally and spatially. Neutrophil depletion dampens necrosis. Neutrophils isolated from mouse brain tumors kill cocultured tumor cells. Mechanistically, neutrophils induce iron-dependent accumulation of lipid peroxides within tumor cells by transferring myeloperoxidase-containing granules into tumor cells. Inhibition or depletion of myeloperoxidase suppresses neutrophil-induced tumor cell cytotoxicity. Intratumoral glutathione peroxidase 4 overexpression or acyl-CoA synthetase long chain family member 4 depletion diminishes necrosis and aggressiveness of tumors. Furthermore, analyses of human GBMs support that neutrophils and ferroptosis are associated with necrosis and predict poor survival. Thus, our study identifies ferroptosis as the underlying nature of necrosis in GBMs and reveals a pro-tumorigenic role of ferroptosis. Together, we propose that certain tumor damage(s) occurring during early tumor progression (i.e. ischemia) recruits neutrophils to the site of tissue damage and thereby results in a positive feedback loop, amplifying GBM necrosis development to its fullest extent. Tumour necrosis is associated with tumour aggressiveness and poor outcomes in patients with glioblastomas, but the underlying mechanisms remain poorly understood. Here, the authors show that in a xenograft mouse model of glioblastoma, tumour-infiltrating neutrophils amplify necrosis by promoting myeloperoxidase-induced tumour cell ferroptosis.
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Fingerhut L, Dolz G, de Buhr N. What Is the Evolutionary Fingerprint in Neutrophil Granulocytes? Int J Mol Sci 2020; 21:E4523. [PMID: 32630520 PMCID: PMC7350212 DOI: 10.3390/ijms21124523] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/19/2020] [Accepted: 06/23/2020] [Indexed: 01/18/2023] Open
Abstract
Over the years of evolution, thousands of different animal species have evolved. All these species require an immune system to defend themselves against invading pathogens. Nevertheless, the immune systems of different species are obviously counteracting against the same pathogen with different efficiency. Therefore, the question arises if the process that was leading to the clades of vertebrates in the animal kingdom-namely mammals, birds, amphibians, reptiles, and fish-was also leading to different functions of immune cells. One cell type of the innate immune system that is transmigrating as first line of defense in infected tissue and counteracts against pathogens is the neutrophil granulocyte. During the host-pathogen interaction they can undergo phagocytosis, apoptosis, degranulation, and form neutrophil extracellular traps (NETs). In this review, we summarize a wide spectrum of information about neutrophils in humans and animals, with a focus on vertebrates. Special attention is kept on the development, morphology, composition, and functions of these cells, but also on dysfunctions and options for cell culture or storage.
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Affiliation(s)
- Leonie Fingerhut
- Department of Physiological Chemistry, Department of Infectious Diseases, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Clinic for Horses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Gaby Dolz
- Escuela de Medicina Veterinaria, Universidad Nacional, Heredia 40104, Costa Rica;
| | - Nicole de Buhr
- Department of Physiological Chemistry, Department of Infectious Diseases, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, 30559 Hannover, Germany
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The redox metabolic pathways function to limit Anaplasma phagocytophilum infection and multiplication while preserving fitness in tick vector cells. Sci Rep 2019; 9:13236. [PMID: 31520000 PMCID: PMC6744499 DOI: 10.1038/s41598-019-49766-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 08/30/2019] [Indexed: 02/06/2023] Open
Abstract
Aerobic organisms evolved conserved mechanisms controlling the generation of reactive oxygen species (ROS) to maintain redox homeostasis signaling and modulate signal transduction, gene expression and cellular functional responses under physiological conditions. The production of ROS by mitochondria is essential in the oxidative stress associated with different pathologies and in response to pathogen infection. Anaplasma phagocytophilum is an intracellular pathogen transmitted by Ixodes scapularis ticks and causing human granulocytic anaplasmosis. Bacteria multiply in vertebrate neutrophils and infect first tick midgut cells and subsequently hemocytes and salivary glands from where transmission occurs. Previous results demonstrated that A. phagocytophilum does not induce the production of ROS as part of its survival strategy in human neutrophils. However, little is known about the role of ROS during pathogen infection in ticks. In this study, the role of tick oxidative stress during A. phagocytophilum infection was characterized through the function of different pathways involved in ROS production. The results showed that tick cells increase mitochondrial ROS production to limit A. phagocytophilum infection, while pathogen inhibits alternative ROS production pathways and apoptosis to preserve cell fitness and facilitate infection. The inhibition of NADPH oxidase-mediated ROS production by pathogen infection appears to occur in both neutrophils and tick cells, thus supporting that A. phagocytophilum uses common mechanisms for infection of ticks and vertebrate hosts. However, differences in ROS response to A. phagocytophilum infection between human and tick cells may reflect host-specific cell tropism that evolved during pathogen life cycle.
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Dumler JS, Sinclair SH, Shetty AC. Alternative Splicing of Differentiated Myeloid Cell Transcripts after Infection by Anaplasma phagocytophilum Impacts a Selective Group of Cellular Programs. Front Cell Infect Microbiol 2018; 8:14. [PMID: 29456968 PMCID: PMC5801399 DOI: 10.3389/fcimb.2018.00014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/12/2018] [Indexed: 12/21/2022] Open
Abstract
Eukaryotic proteome diversity exceeds that encoded within individual genes, and results in part from alternative splicing events of pre-messenger RNA. The diversity of these splicing events can shape the outcome in development and differentiation of normal tissues, and is important in pathogenic circumstances such as cancer and some heritable conditions. A role for alternative splicing of eukaryotic genes in response to viral and intracellular bacterial infections has only recently been recognized, and plays an important role in providing fitness for microbial survival, while potentially enhancing pathogenicity. Anaplasma phagocytophilum survives within mammalian neutrophils by reshaping transcriptional programs that govern cellular functions. We applied next generation RNAseq to ATRA-differentiated HL-60 cells established to possess transcriptional and functional responses similar to A. phagocytophilum-infected human neutrophils. This demonstrated an increase in transcripts with infection and high proportion of alternatively spliced transcript events (ASEs) for which predicted gene ontology processes were in part distinct from those identified by evaluation of single transcripts or gene-level analyses alone. The alternative isoforms are not on average shorter, and no alternative splicing in genes encoding spliceosome components is noted. Although not evident at gene-level analyses, individual spliceosome transcripts that impact nearly all spliceosome components were significantly upregulated. How the distinct GO processes predicted by ASEs are regulated by infection and whether they are relevant to fitness or pathogenicity of A. phagocytophilum should be addressed in more detailed studies.
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Affiliation(s)
- J Stephen Dumler
- Department of Pathology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | | | - Amol C Shetty
- Institute for Genome Sciences, University of Maryland, Baltimore, Baltimore, MD, United States
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Gussmann K, Kirschnek S, von Loewenich FD. Interferon-γ-dependent control of Anaplasma phagocytophilum by murine neutrophil granulocytes. Parasit Vectors 2017; 10:329. [PMID: 28697801 PMCID: PMC5506630 DOI: 10.1186/s13071-017-2274-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/05/2017] [Indexed: 01/06/2023] Open
Abstract
Background Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that is transmitted by ticks of the Ixodes ricinus complex. It replicates in neutrophils and elicits febrile disease in humans and animals. Because of its striking tropism for neutrophils, A. phagocytophilum has been used as a model organism to study the immune response against obligate intracellular pathogens. In mice, the control of A. phagocytophilum in the early phase of infection is dependent on natural killer cell-derived interferon-γ (IFN-γ). In contrast, the final elimination strictly requires CD4+ T-cells. It is a matter of debate, whether neutrophils serve only as host cells or as killer cells as well. Results To study this, we used in vitro generated murine neutrophils with defects in major antimicrobial molecules such as NADPH-oxidase (gp91phox−/−), myeloperoxidase (MPO−/−) and inducible nitric oxide synthase (iNOS−/−). However, bacterial growth in gene-deficient neutrophils was comparable to that in wild-type cells. Whereas gp91phox and MPO expression remained unchanged, the infection led to an induction of iNOS. In neutrophils stimulated with IFN-γ, bacterial growth was significantly impaired, and iNOS was induced. However, the antibacterial effect of IFN-γ was still seen in iNOS−/− neutrophils. Conclusion Thus, murine in vitro generated neutrophils stimulated with IFN-γ seem to act as killer cells by an iNOS-independent mechanism. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2274-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kathrin Gussmann
- Institute of Medical Microbiology and Hygiene, University of Freiburg, Hermann-Herder-Strasse 11, D-79104, Freiburg, Germany
| | - Susanne Kirschnek
- Institute of Medical Microbiology and Hygiene, University of Freiburg, Hermann-Herder-Strasse 11, D-79104, Freiburg, Germany
| | - Friederike D von Loewenich
- Department of Medical Microbiology and Hygiene, University of Mainz, Obere Zahlbacherstrasse 67, D-55131, Mainz, Germany.
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Dumler JS, Sinclair SH, Pappas-Brown V, Shetty AC. Genome-Wide Anaplasma phagocytophilum AnkA-DNA Interactions Are Enriched in Intergenic Regions and Gene Promoters and Correlate with Infection-Induced Differential Gene Expression. Front Cell Infect Microbiol 2016; 6:97. [PMID: 27703927 PMCID: PMC5028410 DOI: 10.3389/fcimb.2016.00097] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/26/2016] [Indexed: 12/16/2022] Open
Abstract
Anaplasma phagocytophilum, an obligate intracellular prokaryote, infects neutrophils, and alters cardinal functions via reprogrammed transcription. Large contiguous regions of neutrophil chromosomes are differentially expressed during infection. Secreted A. phagocytophilum effector AnkA transits into the neutrophil or granulocyte nucleus to complex with DNA in heterochromatin across all chromosomes. AnkA binds to gene promoters to dampen cis-transcription and also has features of matrix attachment region (MAR)-binding proteins that regulate three-dimensional chromatin architecture and coordinate transcriptional programs encoded in topologically-associated chromatin domains. We hypothesize that identification of additional AnkA binding sites will better delineate how A. phagocytophilum infection results in reprogramming of the neutrophil genome. Using AnkA-binding ChIP-seq, we showed that AnkA binds broadly throughout all chromosomes in a reproducible pattern, especially at: (i) intergenic regions predicted to be MARs; (ii) within predicted lamina-associated domains; and (iii) at promoters ≤ 3000 bp upstream of transcriptional start sites. These findings provide genome-wide support for AnkA as a regulator of cis-gene transcription. Moreover, the dominant mark of AnkA in distal intergenic regions known to be AT-enriched, coupled with frequent enrichment in the nuclear lamina, provides strong support for its role as a MAR-binding protein and genome “re-organizer.” AnkA must be considered a prime candidate to promote neutrophil reprogramming and subsequent functional changes that belie improved microbial fitness and pathogenicity.
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Affiliation(s)
- J Stephen Dumler
- Department of Pathology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | | | - Valeria Pappas-Brown
- Department of Pathology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences Bethesda, MD, USA
| | - Amol C Shetty
- Informatics Resource Center, Institute for Genome Sciences, University of Maryland Baltimore, MD, USA
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Global DNA methylation changes and differential gene expression in Anaplasma phagocytophilum-infected human neutrophils. Clin Epigenetics 2015. [PMID: 26225157 PMCID: PMC4518890 DOI: 10.1186/s13148-015-0105-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Background Anaplasma phagocytophilum is an obligate intracellular prokaryotic pathogen that both infects and replicates within human neutrophils. The bacterium represses multiple antimicrobial functions while simultaneously increasing proinflammatory functions by reprogramming the neutrophil genome. Previous reports show that many observed phenotypic changes are in part explained by altered gene transcription. We recently identified that large chromosomal regions of the neutrophil genome are differentially expressed during A. phagocytophilum infection. Because of this, we sought to determine whether gene expression programs altered by infection were the result of changes in the host neutrophil DNA methylome. Results Within 24 h of infection, marked increases in DNA methylation were observed genome-wide as compared with mock-infected controls and pharmacologic inhibition of DNA methyltransferases resulted in decreased bacterial growth. New regions of DNA methylation were enriched at intron and exon junctions; however, intragenic methylation did not correlate with altered gene expression. In contrast, intergenic DNA methylation was associated with A. phagocytophilum-induced gene expression changes. Within the major histocompatibility complex locus on chromosome 6, a region with marked changes in infection-induced differential gene expression, new regions of methylation were localized to boundaries of active and inactive chromatin. Conclusions These data strongly suggest that A. phagocytophilum infection, in addition to altering histone structure, alters DNA methylation and the epigenome of its host cell to promote survival and replication, providing evidence that such bacterial infection can radically alter the epigenome of its host cell. Electronic supplementary material The online version of this article (doi:10.1186/s13148-015-0105-1) contains supplementary material, which is available to authorized users.
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Walker DH, Dumler JS. The role of CD8 T lymphocytes in rickettsial infections. Semin Immunopathol 2015; 37:289-99. [PMID: 25823954 DOI: 10.1007/s00281-015-0480-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 03/15/2015] [Indexed: 12/01/2022]
Abstract
Arthropod-borne obligately intracellular bacteria pose a difficult challenge to the immune system. The genera Rickettsia, Orientia, Ehrlichia, and Anaplasma evolved mechanisms of immune evasion, and each interacts differently with the immune system. The roles of CD8 T cells include protective immunity and immunopathology. In Rickettsia infections, CD8 T cells are protective mediated in part by cytotoxicity toward infected cells. In contrast, TNF-α overproduction by CD8 T cells is pathogenic in lethal ehrlichiosis by induction of apoptosis/necrosis in hepatocytes. Yet, CD8 T cells, along with CD4 T cells and antibodies, also contribute to protective immunity in ehrlichial infections. In granulocytic anaplasmosis, CD8 T cells impact pathogen control modestly but could contribute to immunopathology by virtue of their dysfunction. While preliminary evidence indicates that CD8 T cells are important in protection against Orientia tsutsugamushi, mechanistic studies have been neglected. Valid animal models will enable experiments to elucidate protective and pathologic immune mechanisms. The public health need for vaccines against these agents of human disease, most clearly O. tsutsugamushi, and the veterinary diseases, canine monocytotropic ehrlichiosis (Ehrlichia canis), heartwater (Ehrlichia ruminantium), and bovine anaplasmosis (A. marginale), requires detailed immunity and immunopathology investigations, including the roles of CD8 T lymphocytes.
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Affiliation(s)
- David H Walker
- Department of Pathology, Director, UTMB Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX, 77555-0609, USA,
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Sinclair SHG, Garcia-Garcia JC, Dumler JS. Bioinformatic and mass spectrometry identification of Anaplasma phagocytophilum proteins translocated into host cell nuclei. Front Microbiol 2015; 6:55. [PMID: 25705208 PMCID: PMC4319465 DOI: 10.3389/fmicb.2015.00055] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 01/16/2015] [Indexed: 12/22/2022] Open
Abstract
Obligate intracellular bacteria have an arsenal of proteins that alter host cells to establish and maintain a hospitable environment for replication. Anaplasma phagocytophilum secrets Ankyrin A (AnkA), via a type IV secretion system, which translocates to the nucleus of its host cell, human neutrophils. A. phagocytophilum-infected neutrophils have dramatically altered phenotypes in part explained by AnkA-induced transcriptional alterations. However, it is unlikely that AnkA is the sole effector to account for infection-induced transcriptional changes. We developed a simple method combining bioinformatics and iTRAQ protein profiling to identify potential bacterial-derived nuclear-translocated proteins that could impact transcriptional programming in host cells. This approach identified 50 A. phagocytophilum candidate genes or proteins. The encoding genes were cloned to create GFP fusion protein-expressing clones that were transfected into HEK-293T cells. We confirmed nuclear translocation of six proteins: APH_0062, RplE, Hup, APH_0382, APH_0385, and APH_0455. Of the six, APH_0455 was identified as a type IV secretion substrate and is now under investigation as a potential nucleomodulin. Additionally, application of this approach to other intracellular bacteria such as Mycobacterium tuberculosis, Chlamydia trachomatis and other intracellular bacteria identified multiple candidate genes to be investigated.
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Affiliation(s)
- Sara H G Sinclair
- Graduate Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine Baltimore, MD, USA ; Department of Pathology, The Johns Hopkins University School of Medicine Baltimore, MD, USA ; Department of Pathology, University of Maryland School of Medicine Baltimore, MD, USA ; Department of Microbiology and Immunology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Jose C Garcia-Garcia
- Department of Pathology, The Johns Hopkins University School of Medicine Baltimore, MD, USA ; Procter and Gamble Co. Cincinnati, OH, USA
| | - J Stephen Dumler
- Graduate Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine Baltimore, MD, USA ; Department of Pathology, The Johns Hopkins University School of Medicine Baltimore, MD, USA ; Department of Pathology, University of Maryland School of Medicine Baltimore, MD, USA ; Department of Microbiology and Immunology, University of Maryland School of Medicine Baltimore, MD, USA
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Proctor MC, Leiby DA. Do leukoreduction filters passively reduce the transmission risk of human granulocytic anaplasmosis? Transfusion 2014; 55:1242-8. [DOI: 10.1111/trf.12976] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/11/2014] [Accepted: 11/11/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Melanie C. Proctor
- Transmissible Diseases Department; American Red Cross Holland Laboratory; Rockville Maryland
| | - David A. Leiby
- Transmissible Diseases Department; American Red Cross Holland Laboratory; Rockville Maryland
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Choi KS, Scorpio DG, Dumler JS. Stat1 negatively regulates immune-mediated injury with Anaplasma phagocytophilum infection. THE JOURNAL OF IMMUNOLOGY 2014; 193:5088-98. [PMID: 25305312 DOI: 10.4049/jimmunol.1401381] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human granulocytic anaplasmosis (HGA) is caused by the obligate intracellular bacterium Anaplasma phagocytophilum. Our data previously demonstrated that A. phagocytophilum induces an immunopathologic response by activating IFN-γ production through the Stat1 signaling pathway. In this study, we investigated the broader role of Stat1 signaling in the host response to infection with A. phagocytophilum. In Stat1 knockout (KO) compared with wild-type mice, A. phagocytophilum infection was more highly pathogenic as characterized by the unanticipated development of clinical signs in mice including markedly increased splenomegaly, more severe inflammatory splenic and hepatic histopathology, >100-fold higher blood and splenic bacterial loads, and more elevated proinflammatory cytokine/chemokine responses in serum. CD4(+) and CD8(+) T lymphocyte populations were significantly expanded in spleens of A. phagocytophilum-infected Stat1 KO mice compared with wild-type mice. The leukocyte infiltrates in the livers and spleens of A. phagocytophilum-infected Stat1 KO mice also contained expansions in neutrophil and monocyte/macrophage populations. Importantly, A. phagocytophilum-infected Stat1 KO mice did not demonstrate induction of inducible NO synthase in splenocytes. These results show that Stat1 plays an important role in controlling bacterial loads but also by unexpectedly providing an undefined mechanism for dampening of the immunopathologic response observed with A. phagocytophilum infection.
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Affiliation(s)
- Kyoung-Seong Choi
- Department of Animal Biotechnology, College of Animal Science, Kyungpook National University, Sangju 742-711, Republic of Korea; Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Diana G Scorpio
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205; Department of Biomedical Sciences, Ross University School of Veterinary Medicine, St. Kitts and Nevis, West Indies
| | - J Stephen Dumler
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205; Department of Pathology, University of Maryland, Baltimore, MD 21201; and Department of Microbiology and Immunology, University of Maryland, Baltimore, MD 21201
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