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Petnicki-Ocwieja T, McCarthy JE, Powale U, Langston PK, Helble JD, Hu LT. Borrelia burgdorferi initiates early transcriptional re-programming in macrophages that supports long-term suppression of inflammation. PLoS Pathog 2023; 19:e1011886. [PMID: 38157387 PMCID: PMC10783791 DOI: 10.1371/journal.ppat.1011886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 01/11/2024] [Accepted: 12/06/2023] [Indexed: 01/03/2024] Open
Abstract
Borrelia burgdorferi (Bb), the causative agent of Lyme disease, establishes a long-term infection and leads to disease manifestations that are the result of host immune responses to the pathogen. Inflammatory manifestations resolve spontaneously despite continued bacterial presence, suggesting inflammatory cells become less responsive over time. This is mimicked by in vitro repeated stimulations, resulting in tolerance, a phenotypic subset of innate immune memory. We performed comparative transcriptional analysis of macrophages in acute and memory states and identified sets of Tolerized, Hyper-Induced, Secondary-Induced and Hyper-Suppressed genes resulting from memory induction, revealing previously unexplored networks of genes affected by cellular re-programming. Tolerized gene families included inflammatory mediators and interferon related genes as would be predicted by the attenuation of inflammation over time. To better understand how cells mediate inflammatory hypo-responsiveness, we focused on genes that could mediate maintenance of suppression, such as Hyper-Induced genes which are up-regulated in memory states. These genes were notably enriched in stress pathways regulated by anti-inflammatory modulators. We examined one of the most highly expressed negative regulators of immune pathways during primary stimulation, Aconitate decarboxylase 1 (Acod1), and tested its effects during in vivo infection with Bb. As predicted by our in vitro model, we show its inflammation-suppressive downstream effects are sustained during in vivo long-term infection with Bb, with a specific role in Lyme carditis.
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Affiliation(s)
- Tanja Petnicki-Ocwieja
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Julie E. McCarthy
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Urmila Powale
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Graduate Program in Immunology, Tufts Graduate School of Biomedical Sciences, Boston, Massachusetts, United States of America
| | - P. Kent Langston
- Department of Immunology, Harvard Medical School and Evergrande Center for Immunologic Diseases, Harvard Medical School and Brigham and Women’s Hospital; Boston, Massachusetts, United States of America
| | - Jennifer D. Helble
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Linden T. Hu
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
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2
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The sheep miRNAome: Characterization and distribution of miRNAs in 21 tissues. Gene X 2023; 851:146998. [DOI: 10.1016/j.gene.2022.146998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/10/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022] Open
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3
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Petnicki-Ocwieja T, Sharma B, Powale U, Pathak D, Tan S, Hu LT. An AP-3-dependent pathway directs phagosome fusion with Rab8 and Rab11 vesicles involved in TLR2 signaling. Traffic 2022; 23:558-567. [PMID: 36224049 PMCID: PMC10757455 DOI: 10.1111/tra.12870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 10/03/2022] [Accepted: 10/10/2022] [Indexed: 01/20/2023]
Abstract
Intracellular compartmentalization of ligands, receptors and signaling molecules has been recognized as an important regulator of inflammation. The toll-like receptor (TLR) 2 pathway utilizes the trafficking molecule adaptor protein 3 (AP-3) to activate interleukin (IL)-6 signaling from within phagosomal compartments. To better understand the vesicular pathways that may contribute to intracellular signaling and cooperate with AP-3, we performed a vesicular siRNA screen. We identified Rab8 and Rab11 GTPases as important in IL-6 induction upon stimulation with the TLR2 ligand Pam3 CSK4 or the pathogen, Borrelia burgdorferi (Bb), the causative agent of Lyme disease. These Rabs were recruited to late and lysosomal stage phagosomes and co-transported with TLR2 signaling adaptors and effectors, such as MyD88, TRAM and TAK1, in an AP-3-dependent manner. Our data support a model where AP-3 mediates the recruitment of recycling and secretory vesicles and the assembly of signaling complexes at the phagosome.
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Affiliation(s)
- Tanja Petnicki-Ocwieja
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Bijaya Sharma
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Urmila Powale
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Graduate Program in Immunology, Tufts Graduate School of Biomedical Sciences, Boston, Massachusetts, USA
| | - Devesh Pathak
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Shumin Tan
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Linden T. Hu
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
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4
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Clement M, Forbester JL, Marsden M, Sabberwal P, Sommerville MS, Wellington D, Dimonte S, Clare S, Harcourt K, Yin Z, Nobre L, Antrobus R, Jin B, Chen M, Makvandi-Nejad S, Lindborg JA, Strittmatter SM, Weekes MP, Stanton RJ, Dong T, Humphreys IR. IFITM3 restricts virus-induced inflammatory cytokine production by limiting Nogo-B mediated TLR responses. Nat Commun 2022; 13:5294. [PMID: 36075894 PMCID: PMC9454482 DOI: 10.1038/s41467-022-32587-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 08/08/2022] [Indexed: 11/20/2022] Open
Abstract
Interferon-induced transmembrane protein 3 (IFITM3) is a restriction factor that limits viral pathogenesis and exerts poorly understood immunoregulatory functions. Here, using human and mouse models, we demonstrate that IFITM3 promotes MyD88-dependent, TLR-mediated IL-6 production following exposure to cytomegalovirus (CMV). IFITM3 also restricts IL-6 production in response to influenza and SARS-CoV-2. In dendritic cells, IFITM3 binds to the reticulon 4 isoform Nogo-B and promotes its proteasomal degradation. We reveal that Nogo-B mediates TLR-dependent pro-inflammatory cytokine production and promotes viral pathogenesis in vivo, and in the case of TLR2 responses, this process involves alteration of TLR2 cellular localization. Nogo-B deletion abrogates inflammatory cytokine responses and associated disease in virus-infected IFITM3-deficient mice. Thus, we uncover Nogo-B as a driver of viral pathogenesis and highlight an immunoregulatory pathway in which IFITM3 fine-tunes the responsiveness of myeloid cells to viral stimulation.
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Affiliation(s)
- M Clement
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
| | - J L Forbester
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - M Marsden
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
| | - P Sabberwal
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
| | - M S Sommerville
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
| | - D Wellington
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, Oxford University, Oxford, OX3 9DS, UK
- Chinese Academy of Medical Sciences (CAMS) Oxford Institute (COI), University of Oxford, Oxford, UK
| | - S Dimonte
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
| | - S Clare
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - K Harcourt
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Z Yin
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, Oxford University, Oxford, OX3 9DS, UK
- Chinese Academy of Medical Sciences (CAMS) Oxford Institute (COI), University of Oxford, Oxford, UK
| | - L Nobre
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK
| | - R Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK
| | - B Jin
- Fourth Military Medical University, Xian, China
| | - M Chen
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06536, USA
| | - S Makvandi-Nejad
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, Oxford University, Oxford, OX3 9DS, UK
| | - J A Lindborg
- Departments of Neurology and Neuroscience, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - S M Strittmatter
- Departments of Neurology and Neuroscience, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - M P Weekes
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK
| | - R J Stanton
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
| | - T Dong
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, Oxford University, Oxford, OX3 9DS, UK
- Chinese Academy of Medical Sciences (CAMS) Oxford Institute (COI), University of Oxford, Oxford, UK
| | - I R Humphreys
- Division of Infection and Immunity/Systems Immunity University Research Institute, Cardiff University, Cardiff, CF14 4XN, UK.
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5
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Peruń A, Gębicka M, Biedroń R, Skalska P, Józefowski S. The CD36 and SR-A/CD204 scavenger receptors fine-tune Staphylococcus aureus-stimulated cytokine production in mouse macrophages. Cell Immunol 2022; 372:104483. [DOI: 10.1016/j.cellimm.2022.104483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 12/20/2021] [Accepted: 01/11/2022] [Indexed: 11/03/2022]
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6
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Benjamin SJ, Hawley KL, Vera-Licona P, La Vake CJ, Cervantes JL, Ruan Y, Radolf JD, Salazar JC. Macrophage mediated recognition and clearance of Borrelia burgdorferi elicits MyD88-dependent and -independent phagosomal signals that contribute to phagocytosis and inflammation. BMC Immunol 2021; 22:32. [PMID: 34000990 PMCID: PMC8127205 DOI: 10.1186/s12865-021-00418-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/22/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Macrophages play prominent roles in bacteria recognition and clearance, including Borrelia burgdorferi (Bb), the Lyme disease spirochete. To elucidate mechanisms by which MyD88/TLR signaling enhances clearance of Bb by macrophages, we studied wildtype (WT) and MyD88-/- Bb-stimulated bone marrow-derived macrophages (BMDMs). RESULTS MyD88-/- BMDMs exhibit impaired uptake of spirochetes but comparable maturation of phagosomes following internalization of spirochetes. RNA-sequencing of infected WT and MyD88-/- BMDMs identified a large cohort of differentially expressed MyD88-dependent genes associated with re-organization of actin and cytoskeleton during phagocytosis along with several MyD88-independent chemokines involved in inflammatory cell recruitment. We computationally generated networks which identified several MyD88-dependent intermediate proteins (Rhoq and Cyfip1) that are known to mediate inflammation and phagocytosis respectively. CONCLUSION Our findings show that MyD88 signaling enhances, but is not required, for bacterial uptake or phagosomal maturation and provide mechanistic insights into how MyD88-mediated phagosomal signaling enhances Bb uptake and clearance.
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Affiliation(s)
- Sarah J Benjamin
- Department of Pediatrics, UConn Health, Farmington, CT, 06030, USA
- Department of Immunology, UConn Health, Farmington, CT, 06030, USA
| | - Kelly L Hawley
- Department of Pediatrics, UConn Health, Farmington, CT, 06030, USA
- Division of Infectious Diseases, Connecticut Children's, Hartford, CT, 06106, USA
| | - Paola Vera-Licona
- Department of Pediatrics, UConn Health, Farmington, CT, 06030, USA
- Center for Quantitative Medicine, UConn Health, Farmington, CT, 06030, USA
- Department of Cell Biology, UConn Health, Farmington, CT, 06030, USA
- Institute of Systems Genomics, UConn Health, Farmington, CT, 06030, USA
| | - Carson J La Vake
- Department of Pediatrics, UConn Health, Farmington, CT, 06030, USA
| | - Jorge L Cervantes
- Department of Pediatrics, UConn Health, Farmington, CT, 06030, USA
- Division of Infectious Diseases, Connecticut Children's, Hartford, CT, 06106, USA
- Present Address: Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX, 79905, USA
| | - Yijun Ruan
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Justin D Radolf
- Department of Pediatrics, UConn Health, Farmington, CT, 06030, USA
- Department of Immunology, UConn Health, Farmington, CT, 06030, USA
- Department of Medicine, UConn Health, Farmington, CT, 06030, USA
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, 06030, USA
- Department of Genetics and Genomic Sciences, UConn Health, Farmington, CT, 06030, USA
| | - Juan C Salazar
- Department of Pediatrics, UConn Health, Farmington, CT, 06030, USA.
- Department of Immunology, UConn Health, Farmington, CT, 06030, USA.
- Division of Infectious Diseases, Connecticut Children's, Hartford, CT, 06106, USA.
- Department of Medicine, UConn Health, Farmington, CT, 06030, USA.
- Division of Pediatric Infectious Diseases and Immunology, Connecticut Children's, 282 Washington Street, Hartford, CT, 06106, USA.
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7
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Bockenstedt LK, Wooten RM, Baumgarth N. Immune Response to Borrelia: Lessons from Lyme Disease Spirochetes. Curr Issues Mol Biol 2020; 42:145-190. [PMID: 33289684 PMCID: PMC10842262 DOI: 10.21775/cimb.042.145] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The mammalian host responds to infection with Borrelia spirochetes through a highly orchestrated immune defense involving innate and adaptive effector functions aimed toward limiting pathogen burdens, minimizing tissue injury, and preventing subsequent reinfection. The evolutionary adaptation of Borrelia spirochetes to their reservoir mammalian hosts may allow for its persistence despite this immune defense. This review summarizes our current understanding of the host immune response to B. burgdorferi sensu lato, the most widely studied Borrelia spp. and etiologic agent of Lyme borreliosis. Pertinent literature will be reviewed with emphasis on in vitro, ex vivo and animal studies that influenced our understanding of both the earliest responses to B. burgdorferi as it enters the mammalian host and those that evolve as spirochetes disseminate and establish infection in multiple tissues. Our focus is on the immune response of inbred mice, the most commonly studied animal model of B. burgdorferi infection and surrogate for one of this pathogen's principle natural reservoir hosts, the white-footed deer mouse. Comparison will be made to the immune responses of humans with Lyme borreliosis. Our goal is to provide an understanding of the dynamics of the mammalian immune response during infection with B. burgdorferi and its relation to the outcomes in reservoir (mouse) and non-reservoir (human) hosts.
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Affiliation(s)
- Linda K. Bockenstedt
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8031, USA
| | - R. Mark Wooten
- Department of Medical Microbiology and Immunology, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Nicole Baumgarth
- Center for Immunology and Infectious Diseases and Dept. Pathology, Microbiology and Immunology, University of California, Davis, Davis CA 95616, USA
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8
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Oosenbrug T, van de Graaff MJ, Haks MC, van Kasteren S, Ressing ME. An alternative model for type I interferon induction downstream of human TLR2. J Biol Chem 2020; 295:14325-14342. [PMID: 32796029 DOI: 10.1074/jbc.ra120.015283] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 08/10/2020] [Indexed: 11/06/2022] Open
Abstract
Surface-exposed Toll-like receptors (TLRs) such as TLR2 and TLR4 survey the extracellular environment for pathogens. TLR activation initiates the production of various cytokines and chemokines, including type I interferons (IFN-I). Downstream of TLR4, IFNβ secretion is only vigorously triggered in macrophages when the receptor undergoes endocytosis and switches signaling adaptor; surface TLR4 engagement predominantly induces proinflammatory cytokines via the signaling adaptor MyD88. It is unclear whether this dichotomy is generally applicable to other TLRs, cell types, or differentiation states. Here, we report that diverse TLR2 ligands induce an IFN-I response in human monocyte-like cells, but not in differentiated macrophages. This TLR2-dependent IFN-I signaling originates from the cell surface and depends on MyD88; it involves combined activation of the transcription factors IRF3 and NF-κB, driven by the kinases TBK1 and TAK1-IKKβ, respectively. TLR2-stimulated monocytes produced modest IFNβ levels that caused productive downstream signaling, reflected by STAT1 phosphorylation and expression of numerous interferon-stimulated genes. Our findings reveal that the outcome of TLR2 signaling includes an IFN-I response in human monocytes, which is lost upon macrophage differentiation, and differs mechanistically from IFN-I-induction through TLR4. These findings point to molecular mechanisms tailored to the differentiation state of a cell and the nature of receptors activated to control and limit TLR-triggered IFN-I responses.
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Affiliation(s)
- Timo Oosenbrug
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Michel J van de Graaff
- Department of Bio-organic Synthesis, Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Mariëlle C Haks
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Sander van Kasteren
- Department of Bio-organic Synthesis, Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Maaike E Ressing
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
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9
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Koike S, Yamasaki K, Yamauchi T, Shimada-Omori R, Tsuchiyama K, Aiba S. Toll-like receptor 2 utilizes RAB11A for melanosome transfer from melanocytes to keratinocytes. J Dermatol Sci 2019; 94:310-312. [PMID: 31079998 DOI: 10.1016/j.jdermsci.2019.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/14/2019] [Accepted: 04/24/2019] [Indexed: 11/13/2022]
Affiliation(s)
- Saaya Koike
- Department of Dermatology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Kenshi Yamasaki
- Department of Dermatology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
| | - Takeshi Yamauchi
- Department of Dermatology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Ryoko Shimada-Omori
- Department of Dermatology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Kenichiro Tsuchiyama
- Department of Dermatology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Setsuya Aiba
- Department of Dermatology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
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10
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Response to Letter by Mu et al. Cell Immunol 2017; 322:92. [PMID: 29092753 DOI: 10.1016/j.cellimm.2017.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 10/23/2017] [Indexed: 11/21/2022]
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11
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Phagocytic Receptors Activate Syk and Src Signaling during Borrelia burgdorferi Phagocytosis. Infect Immun 2017; 85:IAI.00004-17. [PMID: 28717031 DOI: 10.1128/iai.00004-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 07/10/2017] [Indexed: 11/20/2022] Open
Abstract
Phagocytosis of the Lyme disease-causing pathogen Borrelia burgdorferi has been shown to be important for generating an inflammatory response to the pathogen. As a result, understanding the mechanisms of phagocytosis has been an area of great interest in the field of Lyme disease. Several cell surface receptors that participate in B. burgdorferi phagocytosis have been reported, including the scavenger receptor MARCO and integrin α3β1. We sought to define the mechanisms by which these receptors mediate phagocytosis and to identify signaling pathways activated downstream of these receptors upon contact with B. burgdorferi We identified both Syk and Src signaling pathways as ones that participate in B. burgdorferi phagocytosis and the resulting cytokine activation. In our studies, we found that both MARCO and integrin β1 play a role in the activation of the Src kinase pathway. However, only integrin β1 participates in the activation of Syk. Interestingly, the integrin activates Syk without the help of the signaling adaptor Dap12 or FcRγ. Thus, we report that multiple pathways participate in B. burgdorferi internalization and that different cell surface receptors act simultaneously in cooperation and independently to mediate phagocytosis.
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12
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The Type II Secretion System of Legionella pneumophila Dampens the MyD88 and Toll-Like Receptor 2 Signaling Pathway in Infected Human Macrophages. Infect Immun 2017; 85:IAI.00897-16. [PMID: 28138020 DOI: 10.1128/iai.00897-16] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/24/2017] [Indexed: 12/25/2022] Open
Abstract
Previously, we reported that mutants of Legionella pneumophila lacking a type II secretion (T2S) system elicit higher levels of cytokines (e.g., interleukin-6 [IL-6]) following infection of U937 cells, a human macrophage-like cell line. We now show that this effect of T2S is also manifest upon infection of human THP-1 macrophages and peripheral blood monocytes but does not occur during infection of murine macrophages. Supporting the hypothesis that T2S acts to dampen the triggering of an innate immune response, we observed that the mitogen-activated protein kinase (MAPK) and nuclear transcription factor kappa B (NF-κB) pathways are more highly stimulated upon infection with the T2S mutant than upon infection with the wild type. By using short hairpin RNA to deplete proteins involved in specific pathogen-associated molecular pattern (PAMP) recognition pathways, we determined that the dampening effect of the T2S system was not dependent on nucleotide binding oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible protein I (RIG-I)-like receptors (RLRs), double-stranded RNA (dsRNA)-dependent protein kinase receptor (PKR), or TIR domain-containing adaptor inducing interferon beta (TRIF) signaling or an apoptosis-associated speck-like protein containing a CARD (ASC)- or caspase-4-dependent inflammasome. However, the dampening effect of T2S on IL-6 production was significantly reduced upon gene knockdown of myeloid differentiation primary response 88 (MyD88), TANK binding kinase 1 (TBK1), or Toll-like receptor 2 (TLR2). These data indicate that the L. pneumophila T2S system dampens the signaling of the TLR2 pathway in infected human macrophages. We also document the importance of PKR, TRIF, and TBK1 in cytokine secretion during L. pneumophila infection of macrophages.
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13
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Tan Y, Kagan JC. Microbe-inducible trafficking pathways that control Toll-like receptor signaling. Traffic 2017; 18:6-17. [PMID: 27731905 PMCID: PMC5182131 DOI: 10.1111/tra.12454] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 10/07/2016] [Accepted: 10/07/2016] [Indexed: 12/12/2022]
Abstract
The receptors of the mammalian innate immune system are designed for rapid microbial detection, and are located in organelles that are conducive to serve these needs. However, emerging evidence indicates that the sites of microbial detection are not the sites of innate immune signal transduction. Rather, microbial detection triggers the movement of receptors to regions of the cell where factors called sorting adaptors detect active receptors and promote downstream inflammatory responses. These findings highlight the critical role that membrane trafficking pathways play in the initiation of innate immunity to infection. In this review, we describe pathways that promote the microbe-inducible endocytosis of Toll-like receptors (TLRs), and the microbe-inducible movement of TLRs between intracellular compartments. We highlight a new class of proteins called Transporters Associated with the eXecution of Inflammation (TAXI), which have the unique ability to transport TLRs and their microbial ligands to signaling-competent regions of the cell, and we discuss the means by which the subcellular sites of signal transduction are defined.
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Affiliation(s)
- Yunhao Tan
- Harvard Medical School and Division of Gastroenterology, Boston Children’s Hospital, Boston, MA, 02115, USA
| | - Jonathan C. Kagan
- Harvard Medical School and Division of Gastroenterology, Boston Children’s Hospital, Boston, MA, 02115, USA
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14
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Shaw DK, Kotsyfakis M, Pedra JHF. For Whom the Bell Tolls (and Nods): Spit-acular Saliva. CURRENT TROPICAL MEDICINE REPORTS 2016; 3:40-50. [PMID: 27547699 DOI: 10.1007/s40475-016-0072-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Having emerged during the early part of the Cretaceous period, ticks are an ancient group of hematophagous ectoparasites with significant veterinary and public health importance worldwide. The success of their life strategy can be attributed, in part, to saliva. As we enter into a scientific era where the collection of massive data sets and structures for biological application is possible, we suggest that understanding the molecular mechanisms that govern the life cycle of ticks is within grasp. With this in mind, we discuss what is currently known regarding the manipulation of Toll-like (TLR) and Nod-like (NLR) receptor signaling pathways by tick salivary proteins, and how these molecules impact pathogen transmission.
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Affiliation(s)
- Dana K Shaw
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
| | - Michail Kotsyfakis
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Budweis, Czech Republic
| | - Joao H F Pedra
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
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