1
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Li J, Xiao C, Li C, He J. Tissue-resident immune cells: from defining characteristics to roles in diseases. Signal Transduct Target Ther 2025; 10:12. [PMID: 39820040 PMCID: PMC11755756 DOI: 10.1038/s41392-024-02050-5] [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: 06/04/2024] [Revised: 09/28/2024] [Accepted: 11/04/2024] [Indexed: 01/19/2025] Open
Abstract
Tissue-resident immune cells (TRICs) are a highly heterogeneous and plastic subpopulation of immune cells that reside in lymphoid or peripheral tissues without recirculation. These cells are endowed with notably distinct capabilities, setting them apart from their circulating leukocyte counterparts. Many studies demonstrate their complex roles in both health and disease, involving the regulation of homeostasis, protection, and destruction. The advancement of tissue-resolution technologies, such as single-cell sequencing and spatiotemporal omics, provides deeper insights into the cell morphology, characteristic markers, and dynamic transcriptional profiles of TRICs. Currently, the reported TRIC population includes tissue-resident T cells, tissue-resident memory B (BRM) cells, tissue-resident innate lymphocytes, tissue-resident macrophages, tissue-resident neutrophils (TRNs), and tissue-resident mast cells, but unignorably the existence of TRNs is controversial. Previous studies focus on one of them in specific tissues or diseases, however, the origins, developmental trajectories, and intercellular cross-talks of every TRIC type are not fully summarized. In addition, a systemic overview of TRICs in disease progression and the development of parallel therapeutic strategies is lacking. Here, we describe the development and function characteristics of all TRIC types and their major roles in health and diseases. We shed light on how to harness TRICs to offer new therapeutic targets and present burning questions in this field.
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Affiliation(s)
- Jia Li
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Chu Xiao
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Chunxiang Li
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Jie He
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
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2
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Martins FRB, de Oliveira MD, Souza JAM, Queiroz-Junior CM, Lobo FP, Teixeira MM, Malacco NL, Soriani FM. Chronic ethanol exposure impairs alveolar leukocyte infiltration during pneumococcal pneumonia, leading to an increased bacterial burden despite increased CXCL1 and nitric oxide levels. Front Immunol 2023; 14:1175275. [PMID: 37275853 PMCID: PMC10235596 DOI: 10.3389/fimmu.2023.1175275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/05/2023] [Indexed: 06/07/2023] Open
Abstract
Ethanol abuse is a risk factor for the development of pneumonia caused by Streptococcus pneumoniae, a critical pathogen for public health. The aim of this article was to investigate the inflammatory mechanisms involved in pneumococcal pneumonia that may be associated with chronic ethanol exposure. Male C57BL6/J-Unib mice were exposed to 20% (v/v) ethanol for twelve weeks and intranasally infected with 5x104 CFU of S. pneumoniae. Twenty-four hours after infection, lungs, bronchoalveolar lavage and blood samples were obtained to assess the consequences of chronic ethanol exposure during infection. Alcohol-fed mice showed increased production of nitric oxide and CXCL1 in alveoli and plasma during pneumococcal pneumonia. Beside this, ethanol-treated mice exhibited a decrease in leukocyte infiltration into the alveoli and reduced frequency of severe lung inflammation, which was associated with an increase in bacterial load. Curiously, no changes were observed in survival after infection. Taken together, these results demonstrate that chronic ethanol exposure alters the inflammatory response during S. pneumoniae lung infection in mice with a reduction in the inflammatory infiltrate even in the presence of higher levels of the chemoattractant CXCL1.
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Affiliation(s)
- Flávia Rayssa Braga Martins
- Department of Genetics, Ecology and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Maycon Douglas de Oliveira
- Department of Genetics, Ecology and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Jéssica Amanda Marques Souza
- Department of Genetics, Ecology and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Celso Martins Queiroz-Junior
- Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Francisco Pereira Lobo
- Department of Genetics, Ecology and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Mauro Martins Teixeira
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - Frederico Marianetti Soriani
- Department of Genetics, Ecology and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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3
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Machado MG, Patente TA, Rouillé Y, Heumel S, Melo EM, Deruyter L, Pourcet B, Sencio V, Teixeira MM, Trottein F. Acetate Improves the Killing of Streptococcus pneumoniae by Alveolar Macrophages via NLRP3 Inflammasome and Glycolysis-HIF-1α Axis. Front Immunol 2022; 13:773261. [PMID: 35126390 PMCID: PMC8810543 DOI: 10.3389/fimmu.2022.773261] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/03/2022] [Indexed: 12/19/2022] Open
Abstract
Short-chain fatty acids (SCFAs) are metabolites produced mainly by the gut microbiota with a known role in immune regulation. Acetate, the major SCFA, is described to disseminate to distal organs such as lungs where it can arm sentinel cells, including alveolar macrophages, to fight against bacterial intruders. In the current study, we explored mechanisms through which acetate boosts macrophages to enhance their bactericidal activity. RNA sequencing analyses show that acetate triggers a transcriptomic program in macrophages evoking changes in metabolic process and immune effector outputs, including nitric oxide (NO) production. In addition, acetate enhances the killing activity of macrophages towards Streptococcus pneumoniae in an NO-dependent manner. Mechanistically, acetate improves IL-1β production by bacteria-conditioned macrophages and the latter acts in an autocrine manner to promote NO production. Strikingly, acetate-triggered IL-1β production was neither dependent of its cell surface receptor free-fatty acid receptor 2, nor of the enzymes responsible for its metabolism, namely acetyl-CoA synthetases 1 and 2. We found that IL-1β production by acetate relies on NLRP3 inflammasome and activation of HIF-1α, the latter being triggered by enhanced glycolysis. In conclusion, we unravel a new mechanism through which acetate reinforces the bactericidal activity of alveolar macrophages.
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Affiliation(s)
- Marina Gomes Machado
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
- Centre National de la Recherche Scientifique, UMR 9017, Lille, France
- Institut National de la Santé et de la Recherche Médicale U1019, Lille, France
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | | | - Yves Rouillé
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
- Centre National de la Recherche Scientifique, UMR 9017, Lille, France
- Institut National de la Santé et de la Recherche Médicale U1019, Lille, France
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
| | - Severine Heumel
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
- Centre National de la Recherche Scientifique, UMR 9017, Lille, France
- Institut National de la Santé et de la Recherche Médicale U1019, Lille, France
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
| | - Eliza Mathias Melo
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Lucie Deruyter
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
- Centre National de la Recherche Scientifique, UMR 9017, Lille, France
- Institut National de la Santé et de la Recherche Médicale U1019, Lille, France
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
| | - Benoit Pourcet
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
- Institut National de la Santé et de la Recherche Médicale U1011, Lille, France
- Univ. Lille, U1011 – European Genomic Institute for Diabetes EGID, Lille, France
| | - Valentin Sencio
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
- Centre National de la Recherche Scientifique, UMR 9017, Lille, France
- Institut National de la Santé et de la Recherche Médicale U1019, Lille, France
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
| | - Mauro Martins Teixeira
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - François Trottein
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
- Centre National de la Recherche Scientifique, UMR 9017, Lille, France
- Institut National de la Santé et de la Recherche Médicale U1019, Lille, France
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
- *Correspondence: François Trottein,
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4
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Tissue-resident immunity in the lung: a first-line defense at the environmental interface. Semin Immunopathol 2022; 44:827-854. [PMID: 36305904 PMCID: PMC9614767 DOI: 10.1007/s00281-022-00964-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 09/08/2022] [Indexed: 12/15/2022]
Abstract
The lung is a vital organ that incessantly faces external environmental challenges. Its homeostasis and unimpeded vital function are ensured by the respiratory epithelium working hand in hand with an intricate fine-tuned tissue-resident immune cell network. Lung tissue-resident immune cells span across the innate and adaptive immunity and protect from infectious agents but can also prove to be pathogenic if dysregulated. Here, we review the innate and adaptive immune cell subtypes comprising lung-resident immunity and discuss their ontogeny and role in distinct respiratory diseases. An improved understanding of the role of lung-resident immunity and how its function is dysregulated under pathological conditions can shed light on the pathogenesis of respiratory diseases.
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5
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Muhammad W, Zhai Z, Wang S, Gao C. Inflammation-modulating nanoparticles for pneumonia therapy. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2021; 14:e1763. [PMID: 34713969 DOI: 10.1002/wnan.1763] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/07/2021] [Accepted: 10/08/2021] [Indexed: 12/23/2022]
Abstract
Pneumonia is a common but serious infectious disease, and is the sixth leading cause for death. The foreign pathogens such as viruses, fungi, and bacteria establish an inflammation response after interaction with lung, leading to the filling of bronchioles and alveoli with fluids. Although the pharmacotherapies have shown their great effectiveness to combat pathogens, advanced methods are under developing to treat complicated cases such as virus-infection and lung inflammation or acute lung injury (ALI). The inflammation modulation nanoparticles (NPs) can effectively suppress immune cells and inhibit inflammatory molecules in the lung site, and thereby alleviate pneumonia and ALI. In this review, the pathological inflammatory microenvironments in pneumonia, which are instructive for the design of biomaterials therapy, are summarized. The focus is then paid to the inflammation-modulating NPs that modulate the inflammatory cells, cytokines and chemokines, and microenvironments of pneumonia for better therapeutic effects. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease.
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Affiliation(s)
- Wali Muhammad
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, China
| | - Zihe Zhai
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, China
| | - Shuqin Wang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, China
| | - Changyou Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, China
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6
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Preston JA, Bewley MA, Marriott HM, McGarry Houghton A, Mohasin M, Jubrail J, Morris L, Stephenson YL, Cross S, Greaves DR, Craig RW, van Rooijen N, Bingle CD, Read RC, Mitchell TJ, Whyte MKB, Shapiro SD, Dockrell DH. Alveolar Macrophage Apoptosis-associated Bacterial Killing Helps Prevent Murine Pneumonia. Am J Respir Crit Care Med 2020; 200:84-97. [PMID: 30649895 DOI: 10.1164/rccm.201804-0646oc] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Rationale: Antimicrobial resistance challenges therapy of pneumonia. Enhancing macrophage microbicidal responses would combat this problem but is limited by our understanding of how alveolar macrophages (AMs) kill bacteria. Objectives: To define the role and mechanism of AM apoptosis-associated bacterial killing in the lung. Methods: We generated a unique CD68.hMcl-1 transgenic mouse with macrophage-specific overexpression of the human antiapoptotic Mcl-1 protein, a factor upregulated in AMs from patients at increased risk of community-acquired pneumonia, to address the requirement for apoptosis-associated killing. Measurements and Main Results: Wild-type and transgenic macrophages demonstrated comparable ingestion and initial phagolysosomal killing of bacteria. Continued ingestion (for ≥12 h) overwhelmed initial killing, and a second, late-phase microbicidal response killed viable bacteria in wild-type macrophages, but this response was blunted in CD68.hMcl-1 transgenic macrophages. The late phase of bacterial killing required both caspase-induced generation of mitochondrial reactive oxygen species and nitric oxide, the peak generation of which coincided with the late phase of killing. The CD68.hMcl-1 transgene prevented mitochondrial reactive oxygen species but not nitric oxide generation. Apoptosis-associated killing enhanced pulmonary clearance of Streptococcus pneumoniae and Haemophilus influenzae in wild-type mice but not CD68.hMcl-1 transgenic mice. Bacterial clearance was enhanced in vivo in CD68.hMcl-1 transgenic mice by reconstitution of apoptosis with BH3 mimetics or clodronate-encapsulated liposomes. Apoptosis-associated killing was not activated during Staphylococcus aureus lung infection. Conclusions: Mcl-1 upregulation prevents macrophage apoptosis-associated killing and establishes that apoptosis-associated killing is required to allow AMs to clear ingested bacteria. Engagement of macrophage apoptosis should be investigated as a novel, host-based antimicrobial strategy.
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Affiliation(s)
- Julie A Preston
- 1 The Florey Institute for Host-Pathogen Interactions and.,2 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom
| | - Martin A Bewley
- 1 The Florey Institute for Host-Pathogen Interactions and.,2 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom
| | - Helen M Marriott
- 1 The Florey Institute for Host-Pathogen Interactions and.,2 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom
| | - A McGarry Houghton
- 3 Clinical Research Division, Fred Hutchinson Cancer Research Center, and.,4 Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, Washington
| | - Mohammed Mohasin
- 5 Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh
| | | | - Lucy Morris
- 1 The Florey Institute for Host-Pathogen Interactions and.,2 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom
| | - Yvonne L Stephenson
- 1 The Florey Institute for Host-Pathogen Interactions and.,2 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom
| | - Simon Cross
- 1 The Florey Institute for Host-Pathogen Interactions and.,2 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom.,7 Sheffield Teaching Hospitals, Sheffield, United Kingdom
| | - David R Greaves
- 8 Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Ruth W Craig
- 9 Department of Pharmacology and Toxicology, Geissel School of Medicine at Dartmouth, Hanover, New Hampshire
| | - Nico van Rooijen
- 10 Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Colin D Bingle
- 1 The Florey Institute for Host-Pathogen Interactions and.,2 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom
| | - Robert C Read
- 11 University of Southampton Medical School, Southampton, United Kingdom.,12 National Institute for Health Research Southampton Biomedical Research Centre, Southampton, United Kingdom
| | - Timothy J Mitchell
- 13 Institute of Microbiology and Infection, School of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom; and
| | - Moira K B Whyte
- 6 MRC Centre for Inflammation Research.,14 Department of Respiratory Medicine, and
| | - Steven D Shapiro
- 15 Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - David H Dockrell
- 6 MRC Centre for Inflammation Research.,16 Infection Medicine, University of Edinburgh, Edinburgh, United Kingdom
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7
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Dolan JM, Weinberg JB, O'Brien E, Abashian A, Procario MC, Aronoff DM, Crofford LJ, Peters-Golden M, Ward L, Mancuso P. Increased lethality and defective pulmonary clearance of Streptococcus pneumoniae in microsomal prostaglandin E synthase-1-knockout mice. Am J Physiol Lung Cell Mol Physiol 2016; 310:L1111-20. [PMID: 27059285 DOI: 10.1152/ajplung.00220.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 03/31/2016] [Indexed: 01/14/2023] Open
Abstract
The production of prostaglandin E2 (PGE2) increases dramatically during pneumococcal pneumonia, and this lipid mediator impairs alveolar macrophage (AM)-mediated innate immune responses. Microsomal prostaglandin E synthase-1 (mPGES-1) is a key enzyme involved in the synthesis of PGE2, and its expression is enhanced during bacterial infections. Genetic deletion of mPGES-1 in mice results in diminished PGE2 production and elevated levels of other prostaglandins after infection. Since PGE2 plays an important immunoregulatory role during bacterial pneumonia we assessed the impact of mPGES-1 deletion in the host defense against pneumococcal pneumonia in vivo and in AMs in vitro. Wild-type (WT) and mPGES-1 knockout (KO) mice were challenged with Streptococcus pneumoniae via the intratracheal route. Compared with WT animals, we observed reduced survival and increased lung and spleen bacterial burdens in mPGES-1 KO mice 24 and 48 h after S. pneumoniae infection. While we found modest differences between WT and mPGES-1 KO mice in pulmonary cytokines, AMs from mPGES-1 KO mice exhibited defective killing of ingested bacteria in vitro that was associated with diminished inducible nitric oxide synthase expression and reduced nitric oxide (NO) synthesis. Treatment of AMs from mPGES-1 KO mice with an NO donor restored bacterial killing in vitro. These results suggest that mPGES-1 plays a critical role in bacterial pneumonia and that genetic ablation of this enzyme results in diminished pulmonary host defense in vivo and in vitro. These results suggest that specific inhibition of PGE2 synthesis by targeting mPGES-1 may weaken host defense against bacterial infections.
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Affiliation(s)
- Jennifer M Dolan
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan
| | - Jason B Weinberg
- Department of Pediatrics and Communicable Disease and Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor, Michigan
| | - Edmund O'Brien
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan
| | - Anya Abashian
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan
| | - Megan C Procario
- Department of Pediatrics and Communicable Disease and Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor, Michigan
| | - David M Aronoff
- Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Leslie J Crofford
- Division of Rheumatology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Marc Peters-Golden
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, School of Medicine, University of Michigan, Ann Arbor, Michigan; Graduate Program in Immunology, University of Michigan, Ann Arbor, Michigan; and
| | - Lindsay Ward
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan
| | - Peter Mancuso
- Graduate Program in Immunology, University of Michigan, Ann Arbor, Michigan; and Department of Nutritional Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan
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8
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Stolberg VR, McCubbrey AL, Freeman CM, Brown JP, Crudgington SW, Taitano SH, Saxton BL, Mancuso P, Curtis JL. Glucocorticoid-Augmented Efferocytosis Inhibits Pulmonary Pneumococcal Clearance in Mice by Reducing Alveolar Macrophage Bactericidal Function. THE JOURNAL OF IMMUNOLOGY 2015; 195:174-84. [PMID: 25987742 DOI: 10.4049/jimmunol.1402217] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 04/22/2015] [Indexed: 12/31/2022]
Abstract
Inhaled corticosteroids (ICS) increase community-acquired pneumonia (CAP) incidence in patients with chronic obstructive pulmonary disease (COPD) by unknown mechanisms. Apoptosis is increased in the lungs of COPD patients. Uptake of apoptotic cells (ACs) ("efferocytosis") by alveolar macrophages (AMøs) reduces their ability to combat microbes, including Streptococcus pneumoniae, the most common cause of CAP in COPD patients. Having shown that ICS significantly increase AMø efferocytosis, we hypothesized that this process, termed glucocorticoid-augmented efferocytosis, might explain the association of CAP with ICS therapy in COPD. To test this hypothesis, we studied the effects of fluticasone, AC, or both on AMøs of C57BL/6 mice in vitro and in an established model of pneumococcal pneumonia. Fluticasone plus AC significantly reduced TLR4-stimulated AMø IL-12 production, relative to either treatment alone, and decreased TNF-α, CCL3, CCL5, and keratinocyte-derived chemoattractant/CXCL1, relative to AC. Mice treated with fluticasone plus AC before infection with viable pneumococci developed significantly more lung CFUs at 48 h. However, none of the pretreatments altered inflammatory cell recruitment to the lungs at 48 h postinfection, and fluticasone plus AC less markedly reduced in vitro mediator production to heat-killed pneumococci. Fluticasone plus AC significantly reduced in vitro AMø killing of pneumococci, relative to other conditions, in part by delaying phagolysosome acidification without affecting production of reactive oxygen or nitrogen species. These results support glucocorticoid-augmented efferocytosis as a potential explanation for the epidemiological association of ICS therapy of COPD patients with increased risk for CAP, and establish murine experimental models to dissect underlying molecular mechanisms.
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Affiliation(s)
| | | | - Christine M Freeman
- Research Service, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109
| | - Jeanette P Brown
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109
| | - Sean W Crudgington
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109
| | - Sophina H Taitano
- Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109
| | | | - Peter Mancuso
- Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109; Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109; and
| | - Jeffrey L Curtis
- Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109; Medical Service, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105
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9
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Knippenberg S, Brumshagen C, Aschenbrenner F, Welte T, Maus UA. Arginase 1 activity worsens lung-protective immunity against Streptococcus pneumoniae infection. Eur J Immunol 2015; 45:1716-26. [PMID: 25789453 DOI: 10.1002/eji.201445419] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/05/2015] [Accepted: 03/16/2015] [Indexed: 12/21/2022]
Abstract
Type 2 helper cell (Th2) dominated chronic lung diseases such as asthma are characterized by an increased risk for bacterial lung infections. However, the underlying mechanisms are poorly defined. Arginase 1 (Arg1) has been suggested to play an important role in the pathophysiology of asthma, and is rapidly induced in lung macrophages by Th2 cytokines, thereby limiting macrophage-derived antimicrobial nitric oxide (NO) production. Here we examined the effect of Th2 cytokine induced upregulation or lung myeloid cell specific conditional knockdown of Arg1 on lung resistance against Streptococcus pneumoniae (Spn) in mice. Lung macrophages responded with a profound induction of Arg1 mRNA and protein to treatment with IL-13 both in vitro and in vivo. IL-13-induced Arg1 activity in the lungs of mice led to significantly attenuated lung-protective immunity against Spn, while conditional Arg1 knockdown had no effect on lung-protective immunity against Spn. Collectively, the data show that Th2 cytokine induced increased Arg1 activity worsens lung-protective immunity against Spn, and interventions to block Th2 cytokine induced lung Arg1 activity may thus be a novel immunomodulatory strategy to lower the risk of bacterial infections in asthmatic patients.
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Affiliation(s)
- Sarah Knippenberg
- Department of Experimental Pneumology, Hannover Medical School, Hannover, Germany
| | - Christina Brumshagen
- Department of Experimental Pneumology, Hannover Medical School, Hannover, Germany
| | | | - Tobias Welte
- Department of Experimental Pneumology, Hannover Medical School, Hannover, Germany.,German Centre for Lung Research BREATH, Hannover, Germany
| | - Ulrich A Maus
- Department of Experimental Pneumology, Hannover Medical School, Hannover, Germany.,German Centre for Lung Research BREATH, Hannover, Germany
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10
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Cole J, Aberdein J, Jubrail J, Dockrell DH. The role of macrophages in the innate immune response to Streptococcus pneumoniae and Staphylococcus aureus: mechanisms and contrasts. Adv Microb Physiol 2014; 65:125-202. [PMID: 25476766 DOI: 10.1016/bs.ampbs.2014.08.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Macrophages are critical mediators of innate immune responses against bacteria. The Gram-positive bacteria Streptococcus pneumoniae and Staphylococcus aureus express a range of virulence factors, which challenge macrophages' immune competence. We review how macrophages respond to this challenge. Macrophages employ a range of strategies to phagocytose and kill each pathogen. When the macrophages capacity to clear bacteria is overwhelmed macrophages play important roles in orchestrating the inflammatory response through pattern recognition receptor-mediated responses. Macrophages also ensure the inflammatory response is tightly constrained, to avoid tissue damage, and play an important role in downregulating the inflammatory response once initial bacterial replication is controlled.
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Affiliation(s)
- Joby Cole
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom
| | - Jody Aberdein
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom
| | - Jamil Jubrail
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom
| | - David H Dockrell
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, United Kingdom.
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11
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Sun K, Metzger DW. Influenza infection suppresses NADPH oxidase-dependent phagocytic bacterial clearance and enhances susceptibility to secondary methicillin-resistant Staphylococcus aureus infection. THE JOURNAL OF IMMUNOLOGY 2014; 192:3301-7. [PMID: 24563256 DOI: 10.4049/jimmunol.1303049] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading contributor to mortality during recent influenza pandemics. The mechanism for this influenza-induced susceptibility to secondary S. aureus infection is poorly understood. In this study, we show that innate antibacterial immunity was significantly suppressed during the recovery stage of influenza infection, even though MRSA superinfection had no significant effect on viral burdens. Compared with mice infected with bacteria alone, postinfluenza MRSA-infected mice exhibited impaired bacterial clearance, which was not due to defective phagocyte recruitment, but rather coincided with reduced intracellular reactive oxygen species levels in alveolar macrophages and neutrophils. NADPH oxidase is responsible for reactive oxygen species production during phagocytic bacterial killing, a process also known as oxidative burst. We found that gp91(phox)-containing NADPH oxidase activity in macrophages and neutrophils was essential for optimal bacterial clearance during respiratory MRSA infections. In contrast to wild-type animals, gp91(phox-/-) mice exhibited similar defects in MRSA clearance before and after influenza infection. Using gp91(phox+/-) mosaic mice, we further demonstrate that influenza infection inhibits a cell-intrinsic contribution of NADPH oxidase to phagocyte bactericidal activity. Taken together, our results establish that influenza infection suppresses NADPH oxidase-dependent bacterial clearance and leads to susceptibility to secondary MRSA infection.
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Affiliation(s)
- Keer Sun
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208
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12
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Abstract
Reactive oxygen species (ROS) are deadly weapons used by phagocytes and other cell types, such as lung epithelial cells, against pathogens. ROS can kill pathogens directly by causing oxidative damage to biocompounds or indirectly by stimulating pathogen elimination by various nonoxidative mechanisms, including pattern recognition receptors signaling, autophagy, neutrophil extracellular trap formation, and T-lymphocyte responses. Thus, one should expect that the inhibition of ROS production promote infection. Increasing evidences support that in certain particular infections, antioxidants decrease and prooxidants increase pathogen burden. In this study, we review the classic infections that are controlled by ROS and the cases in which ROS appear as promoters of infection, challenging the paradigm. We discuss the possible mechanisms by which ROS could promote particular infections. These mechanisms are still not completely clear but include the metabolic effects of ROS on pathogen physiology, ROS-induced damage to the immune system, and ROS-induced activation of immune defense mechanisms that are subsequently hijacked by particular pathogens to act against more effective microbicidal mechanisms of the immune system. The effective use of antioxidants as therapeutic agents against certain infections is a realistic possibility that is beginning to be applied against viruses.
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Affiliation(s)
- Claudia N Paiva
- Departamento de Imunologia, Instituto de Microbiologia , CCS Bloco D, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
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13
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Messias-Reason IJT, van Tong H, Velavan TP. Analysis of polymorphic sites in the promoter of the nitric oxide synthase 2 gene in Brazilian patients with leprosy. Int J Immunogenet 2014; 41:231-5. [PMID: 24495190 DOI: 10.1111/iji.12108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/26/2013] [Accepted: 12/19/2013] [Indexed: 12/01/2022]
Abstract
Leprosy is one of the most neglected infectious tropical diseases of the skin and the nerves caused by the intracellular pathogen Mycobacterium leprae. The inducible NOS isoform encoded by NOS2A plays a vital role in host defence against bacterial infections. The functional promoter polymorphisms in NOS2A are associated with various autoimmune and infectious diseases. We investigated the association of NOS2A variants with progression of leprosy in a Brazilian cohort including 221 clinically classified patients and 103 unrelated healthy controls. We observed a novel variant ss528838018A/G in the promoter region at position -6558. The other functional variants were observed with low frequency of minor allele (<0.005). NOS2A promoter variant (-954G/C) was not observed in Brazilian populations, and the new observed promoter variant (ss528838018A/G) as well as other promoter variants were not associated with any clinical forms of leprosy in the Brazilian populations.
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Affiliation(s)
- I J T Messias-Reason
- Laboratório de Imunopatologia Molecular, Departamento de Patologia Médica, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, Brazil
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14
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Aberdein JD, Cole J, Bewley MA, Marriott HM, Dockrell DH. Alveolar macrophages in pulmonary host defence the unrecognized role of apoptosis as a mechanism of intracellular bacterial killing. Clin Exp Immunol 2013; 174:193-202. [PMID: 23841514 DOI: 10.1111/cei.12170] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/04/2013] [Indexed: 01/12/2023] Open
Abstract
Alveolar macrophages play an essential role in clearing bacteria from the lower airway, as the resident phagocyte alveolar macrophages must both phagocytose and kill bacteria, and if unable to do this completely must co-ordinate an inflammatory response. The decision to escalate the inflammatory response represents the transition between subclinical infection and the development of pneumonia. Alveolar macrophages are well equipped to phagocytose bacteria and have a large phagolysosomal capacity in which ingested bacteria are killed. The rate-limiting step in control of extracellular bacteria, such as Streptococcus pneumoniae, is the capacity of alveolar macrophages to kill ingested bacteria. Therefore, alveolar macrophages complement canonical microbicidal strategies with an additional level of apoptosis-associated killing to help kill ingested bacteria.
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Affiliation(s)
- J D Aberdein
- Department of Infection and Immunity, University of Sheffield Medical School and Sheffield Teaching Hospitals, Sheffield, UK
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15
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Abstract
Reactive oxygen species (ROS) have profound influences on cellular homeostasis. In excess, they can potentiate the oxidation of numerous molecules, including proteins, lipids, and nucleic acids, affecting function. Furthermore, ROS-mediated oxidation of proteins can directly or indirectly modulate gene expression via effects on redox-sensitive transcription factors or via effects on phospho-relay-mediated signal transduction. In doing so, ROS impact numerous fundamental cellular processes, and have thus been implicated as critical mediators of both homeostasis and disease pathogenesis. Vascular reduced nicotinamide adenine dinucleotide phosphate oxidase (NOX) is a major contributor of ROS within the lung. The generation of ROS in the pulmonary vasculature has a pivotal role in endothelial cell (EC) activation and function. Alterations in EC phenotype contribute to vascular tone, permeability, and inflammatory responses and, thus, have been implicated in numerous diseases of the lung, including pulmonary hypertension, ischemic-reperfusion injury, and adult respiratory distress syndrome. Thus, although a detailed understanding of NOX-derived ROS in pulmonary EC biology in the context of health and disease is nascent, there is mounting evidence implicating these enzymes as critical modifiers of diseases of the lung and pulmonary circulation. The purpose of this review is to focus specifically on known as well as putative roles for pulmonary EC NOX, with attention to studies on the intact lung.
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Affiliation(s)
- Rachel Damico
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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16
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Bewley MA, Marriott HM, Tulone C, Francis SE, Mitchell TJ, Read RC, Chain B, Kroemer G, Whyte MKB, Dockrell DH. A cardinal role for cathepsin d in co-ordinating the host-mediated apoptosis of macrophages and killing of pneumococci. PLoS Pathog 2011; 7:e1001262. [PMID: 21298030 PMCID: PMC3029254 DOI: 10.1371/journal.ppat.1001262] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 12/21/2010] [Indexed: 11/23/2022] Open
Abstract
The bactericidal function of macrophages against pneumococci is enhanced by their apoptotic demise, which is controlled by the anti-apoptotic protein Mcl-1. Here, we show that lysosomal membrane permeabilization (LMP) and cytosolic translocation of activated cathepsin D occur prior to activation of a mitochondrial pathway of macrophage apoptosis. Pharmacological inhibition or knockout of cathepsin D during pneumococcal infection blocked macrophage apoptosis. As a result of cathepsin D activation, Mcl-1 interacted with its ubiquitin ligase Mule and expression declined. Inhibition of cathepsin D had no effect on early bacterial killing but inhibited the late phase of apoptosis-associated killing of pneumococci in vitro. Mice bearing a cathepsin D−/− hematopoietic system demonstrated reduced macrophage apoptosis in vivo, with decreased clearance of pneumococci and enhanced recruitment of neutrophils to control pulmonary infection. These findings establish an unexpected role for a cathepsin D-mediated lysosomal pathway of apoptosis in pulmonary host defense and underscore the importance of apoptosis-associated microbial killing to macrophage function. Tissue macrophages frequently undergo a program of cell death, termed apoptosis, following sustained ingestion and killing of bacteria. In macrophages, induction of apoptosis enhances bacterial killing when macrophages' initial killing capacity is exhausted. We have investigated the mechanism of apoptosis in macrophages exposed to pneumococci, the commonest cause of bacterial pneumonia. We show that the cell structure containing ingested bacteria, the phagolysosome, becomes permeabilized early in the death process. Pneumococcal exposure activates a phagolysosomal enzyme, cathepsin D, which induces apoptosis. Cathepsin D activation is required for permeabilization of mitochondria, an organelle implicated in apoptosis induction. Cathepsin D reduces levels of a negative regulator of apoptosis in macrophages, Mcl-1, by enhancing its association with an enzyme, which mediates its degradation. The importance of these findings was confirmed in a bone marrow transplant model in which mice either received bone marrow from mice containing or lacking the cathepsin D gene. This model showed that reduced apoptosis of alveolar macrophages occurred when cathepsin D was lacking, and that this impaired clearance of pneumococci in the mouse lung. We conclude that during bacterial challenge, lysosomal permeabilization and cathepsin D activation triggers a novel death pathway, in a timely fashion, linking bacterial killing to apoptosis induction.
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Affiliation(s)
- Martin A Bewley
- Medical School, University of Sheffield, Sheffield, United Kingdom
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17
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Payton A, Payne D, Mankhambo LA, Banda DL, Hart CA, Ollier WER, Carrol ED. Nitric oxide synthase 2A (NOS2A) polymorphisms are not associated with invasive pneumococcal disease. BMC MEDICAL GENETICS 2009; 10:28. [PMID: 19309520 PMCID: PMC2666671 DOI: 10.1186/1471-2350-10-28] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 03/23/2009] [Indexed: 11/21/2022]
Abstract
BACKGROUND Streptococcus pneumoniae (pneumococcus) is responsible for over one million deaths per year, with young children, the elderly and immunocompromised individuals being most at risk. Approximately half of East African children have been reported to be asymptomatic carriers of pneumococcus with invasive infection occurring after the disruption of the respiratory membrane which is believed to be caused by the host immune response. Racial incidence of invasive pneumococcal disease (IPD) is higher in certain populations even after adjusting for environmental factors suggesting a genetic component to disease susceptibility. The nitric oxide synthase 2A (NOS2A) gene is responsible for the production of nitric oxide under pathological conditions including host defence against bacterial infection. Nitric oxide is a modulator of apoptotic and inflammatory cascades and endothelial permeability. We hypothesised that genetic variants within this gene may predispose to disease risk and survival. METHODS A cohort of 299 children with IPD (221 meningitis, 41 pneumonia and 37 with bacteraemia) and 931 age matched controls from Malawi were used in this study. We investigated nine haplotype tagging single nucleotide polymorphisms within the NOS2A gene and compared the presence or absence of the minor alleles in cases and controls and survivors and non-survivors within the cases. RESULTS We observed no significant associations between cases and controls or with survival in either all IPD cases or in the separate analysis of meningitis cases. A near significant association was obtained for the comparison of rs8078340 in cases and controls (p-value, 0.078). However, results were unadjusted for multiple testing. CONCLUSION Our results suggest that polymorphic variation within the NOS2A gene does not influence invasive pneumococcal disease susceptibility or survival.
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Affiliation(s)
- Antony Payton
- Centre for Integrated Genomic Medical Research, Stopford building, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Debbie Payne
- Centre for Integrated Genomic Medical Research, Stopford building, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Limangeni A Mankhambo
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, PO Box 30096, Blantyre, Malawi
| | - Daniel L Banda
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, PO Box 30096, Blantyre, Malawi
| | - C Anthony Hart
- Division of Medical Microbiology, University of Liverpool, Daulby Street, Liverpool, L69 3GA, UK
| | - William ER Ollier
- Centre for Integrated Genomic Medical Research, Stopford building, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Enitan D Carrol
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, PO Box 30096, Blantyre, Malawi
- Division of Medical Microbiology, University of Liverpool, Daulby Street, Liverpool, L69 3GA, UK
- Division of Child Health, University of Liverpool, Alder Hey Children's NHS Foundation Trust,, Eaton Road, Liverpool, L12 2AP, UK
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18
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Marriott HM, Dockrell DH. The role of the macrophage in lung disease mediated by bacteria. Exp Lung Res 2008; 33:493-505. [PMID: 18075824 DOI: 10.1080/01902140701756562] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Respiratory infections are a major cause of human morbidity and a leading cause of death. The lower respiratory tract is a sterile environment and host defense is well developed to clear bacteria. This response includes both humeral factors and resident and recruited cells. The alveolar macrophage is an integral component and its long-lifespan aids function. Following low-dose challenge alveolar macrophages clear bacteria from the lung, employing an over-lapping set of microbicidal strategies. At a higher-dose the phagocytic capacity of alveolar macrophages is overwhelmed but alveolar macrophages help orchestrate the inflammatory response. In the resolution phase of infection alveolar macrophages contribute to apoptosis induction and clearance of recruited cells. This process down-regulates pro-inflammatory cytokine production. Macrophage function is controlled by induction of apoptosis. Delayed-onset macrophage apoptosis contributes both to bacterial clearance and to resolution of the inflammatory response. Mcl-1, an anti-apoptotic protein with a very short half-life, is a key regulator of macrophage survival and therefore of host responses to common bacterial pathogens in the lung. Studies involving Streptococcus pneumoniae and other respiratory bacteria are discussed to illustrate these points and ephasise that the timing of macrophage apoptosis is important in determining its overall effect on the host pathogen interaction.
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Affiliation(s)
- Helen M Marriott
- Section of Infection, Inflammation and Immunity, University of Sheffield School of Medicine and Biomedical Sciences, Sheffield, UK
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19
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Cruz AR, Moore MW, La Vake CJ, Eggers CH, Salazar JC, Radolf JD. Phagocytosis of Borrelia burgdorferi, the Lyme disease spirochete, potentiates innate immune activation and induces apoptosis in human monocytes. Infect Immun 2008; 76:56-70. [PMID: 17938216 PMCID: PMC2223637 DOI: 10.1128/iai.01039-07] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Revised: 09/07/2007] [Accepted: 10/08/2007] [Indexed: 01/07/2023] Open
Abstract
We have previously demonstrated that phagocytosed Borrelia burgdorferi induces activation programs in human peripheral blood mononuclear cells that differ qualitatively and quantitatively from those evoked by equivalent lipoprotein-rich lysates. Here we report that ingested B. burgdorferi induces significantly greater transcription of proinflammatory cytokine genes than do lysates and that live B. burgdorferi, but not B. burgdorferi lysate, is avidly internalized by monocytes, where the bacteria are completely degraded within phagolysosomes. In the course of these experiments, we discovered that live B. burgdorferi also induced a dose-dependent decrease in monocytes but not a decrease in dendritic cells or T cells and that the monocyte population displayed morphological and biochemical hallmarks of apoptosis. Particularly noteworthy was the finding that apoptotic changes occurred predominantly in monocytes that had internalized spirochetes. Abrogation of phagocytosis with cytochalasin D prevented the death response. Heat-killed B. burgdorferi, which was internalized as well as live organisms, induced a similar degree of apoptosis of monocytes but markedly less cytokine production. Surprisingly, opsonophagocytosis of Treponema pallidum did not elicit a discernible cell death response. Our combined results demonstrate that B. burgdorferi confined to phagolysosomes is a potent inducer of cytosolic signals that result in (i) production of NF-kappaB-dependent cytokines, (ii) assembly of the inflammasome and activation of caspase-1, and (iii) induction of programmed cell death. We propose that inflammation and apoptosis represent mutually reinforcing components of the immunologic arsenal that the host mobilizes to defend itself against infection with Lyme disease spirochetes.
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Affiliation(s)
- Adriana R Cruz
- Department of Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3715, USA
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