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Wheeler R, Gomperts Boneca I. The hidden base of the iceberg: gut peptidoglycome dynamics is foundational to its influence on the host. Gut Microbes 2024; 16:2395099. [PMID: 39239828 PMCID: PMC11382707 DOI: 10.1080/19490976.2024.2395099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 07/01/2024] [Accepted: 08/16/2024] [Indexed: 09/07/2024] Open
Abstract
The intestinal microbiota of humans includes a highly diverse range of bacterial species. All these bacteria possess a cell wall, composed primarily of the macromolecule peptidoglycan. As such, the gut also harbors an abundant and varied peptidoglycome. A remarkable range of host physiological pathways are regulated by peptidoglycan fragments that originate from the gut microbiota and enter the host system. Interactions between the host system and peptidoglycan can influence physiological development and homeostasis, promote health, or contribute to inflammatory disease. Underlying these effects is the interplay between microbiota composition and enzymatic processes that shape the intestinal peptidoglycome, dictating the types of peptidoglycan generated, that subsequently cross the gut barrier. In this review, we highlight and discuss the hidden and emerging functional aspects of the microbiome, i.e. the hidden base of the iceberg, that modulate the composition of gut peptidoglycan, and how these fundamental processes are drivers of physiological outcomes for the host.
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Affiliation(s)
- Richard Wheeler
- Institut Pasteur, Université Paris Cité, Paris, France
- Hauts-de-Seine, Arthritis Research and Development, Neuilly-sur-Seine, France
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2
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Abstract
Mycobacteria are responsible for several human and animal diseases. NOD2 is a pattern recognition receptor that has an important role in mycobacterial recognition. However, the mechanisms by which mutations in NOD2 alter the course of mycobacterial infection remain unclear. Herein, we aimed to review the totality of studies directly addressing the relationship between NOD2 and mycobacteria as a foundation for moving the field forward. NOD2 was linked to mycobacterial infection at 3 levels: (1) genetic, through association with mycobacterial diseases of humans; (2) chemical, through the distinct NOD2 ligand in the mycobacterial cell wall; and (3) immunologic, through heightened NOD2 signaling caused by the unique modification of the NOD2 ligand. The immune response to mycobacteria is shaped by NOD2 signaling, responsible for NF-κB and MAPK activation, and the production of various immune effectors like cytokines and nitric oxide, with some evidence linking this to bacteriologic control. Absence of NOD2 during mycobacterial infection of mice can be detrimental, but the mechanism remains unknown. Conversely, the success of immunization with mycobacteria has been linked to NOD2 signaling and NOD2 has been targeted as an avenue of immunotherapy for diseases even beyond mycobacteria. The mycobacteria-NOD2 interaction remains an important area of study, which may shed light on immune mechanisms in disease.
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Affiliation(s)
- Jean-Yves Dubé
- Department of Microbiology and Immunology, McGill University, Montréal, Canada
| | - Marcel A Behr
- Department of Medicine, McGill University Health Centre, Montréal, Canada
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3
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Matsuzawa-Ishimoto Y, Yao X, Koide A, Ueberheide BM, Axelrad JE, Reis BS, Parsa R, Neil JA, Devlin JC, Rudensky E, Dewan MZ, Cammer M, Blumberg RS, Ding Y, Ruggles KV, Mucida D, Koide S, Cadwell K. The γδ IEL effector API5 masks genetic susceptibility to Paneth cell death. Nature 2022; 610:547-554. [PMID: 36198790 PMCID: PMC9720609 DOI: 10.1038/s41586-022-05259-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 08/22/2022] [Indexed: 01/26/2023]
Abstract
Loss of Paneth cells and their antimicrobial granules compromises the intestinal epithelial barrier and is associated with Crohn's disease, a major type of inflammatory bowel disease1-7. Non-classical lymphoid cells, broadly referred to as intraepithelial lymphocytes (IELs), intercalate the intestinal epithelium8,9. This anatomical position has implicated them as first-line defenders in resistance to infections, but their role in inflammatory disease pathogenesis requires clarification. The identification of mediators that coordinate crosstalk between specific IEL and epithelial subsets could provide insight into intestinal barrier mechanisms in health and disease. Here we show that the subset of IELs that express γ and δ T cell receptor subunits (γδ IELs) promotes the viability of Paneth cells deficient in the Crohn's disease susceptibility gene ATG16L1. Using an ex vivo lymphocyte-epithelium co-culture system, we identified apoptosis inhibitor 5 (API5) as a Paneth cell-protective factor secreted by γδ IELs. In the Atg16l1-mutant mouse model, viral infection induced a loss of Paneth cells and enhanced susceptibility to intestinal injury by inhibiting the secretion of API5 from γδ IELs. Therapeutic administration of recombinant API5 protected Paneth cells in vivo in mice and ex vivo in human organoids with the ATG16L1 risk allele. Thus, we identify API5 as a protective γδ IEL effector that masks genetic susceptibility to Paneth cell death.
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Affiliation(s)
- Yu Matsuzawa-Ishimoto
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY, USA.,Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Xiaomin Yao
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY, USA.,Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Akiko Koide
- Perlmutter Cancer Center, NYU Langone Health, New York, NY 10016,Department of Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | - Beatrix M. Ueberheide
- Perlmutter Cancer Center, NYU Langone Health, New York, NY 10016,Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA,Proteomics Laboratory, Division of Advanced Research Technologies, New York University Grossman School of Medicine, New York, NY, USA,Department of Neurology, New York University Grossman School of Medicine, New York, NY, USA
| | - Jordan E. Axelrad
- Division of Gastroenterology and Hepatology, Department of Medicine, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Bernardo S. Reis
- Laboratory of Mucosal Immunology, The Rockefeller University, New York, NY, USA
| | - Roham Parsa
- Laboratory of Mucosal Immunology, The Rockefeller University, New York, NY, USA
| | - Jessica A. Neil
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY, USA.,Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Joseph C. Devlin
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Eugene Rudensky
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY, USA.,Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - M Zahidunnabi Dewan
- Experimental Pathology, Division of Advanced Research Technologies, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Michael Cammer
- Microscopy Laboratory, Division of Advanced Research Technologies, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Richard S. Blumberg
- Division of Gastroenterology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Yi Ding
- Department of Laboratory Medicine, Geisinger Health, Danville, PA 17822, USA
| | - Kelly V. Ruggles
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY, USA,Division of Translational Medicine, Department of Medicine, New York University Grossman School of Medicine, New York, NY, USA
| | - Daniel Mucida
- Department of Neurology, New York University Grossman School of Medicine, New York, NY, USA,Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA
| | - Shohei Koide
- Perlmutter Cancer Center, NYU Langone Health, New York, NY 10016,Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, USA,Corresponding author: Ken Cadwell, Address: 430 East 29th street, 4th Floor, New York, NY 10016, , Phone: 212-263-8891, Fax: 212-263-5711, Shohei Koide, Address: 522 1st Avenue, Smilow Research Center, 8th floor, New York, NY 10016, , Phone: 646-501-4601
| | - Ken Cadwell
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University Grossman School of Medicine, New York, NY, USA.,Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA.,Division of Gastroenterology and Hepatology, Department of Medicine, New York University Grossman School of Medicine, New York, NY 10016, USA,Corresponding author: Ken Cadwell, Address: 430 East 29th street, 4th Floor, New York, NY 10016, , Phone: 212-263-8891, Fax: 212-263-5711, Shohei Koide, Address: 522 1st Avenue, Smilow Research Center, 8th floor, New York, NY 10016, , Phone: 646-501-4601
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4
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The Gut Microbiota in Cardiovascular Disease and Arterial Thrombosis. Microorganisms 2019; 7:microorganisms7120691. [PMID: 31847071 PMCID: PMC6956001 DOI: 10.3390/microorganisms7120691] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/06/2019] [Accepted: 12/11/2019] [Indexed: 12/16/2022] Open
Abstract
The gut microbiota has emerged as a contributing factor in the development of atherosclerosis and arterial thrombosis. Metabolites from the gut microbiota, such as trimethylamine N-oxide and short chain fatty acids, were identified as messengers that induce cell type-specific signaling mechanisms and immune reactions in the host vasculature, impacting the development of cardiovascular diseases. In addition, microbial-associated molecular patterns drive atherogenesis and the microbiota was recently demonstrated to promote arterial thrombosis through Toll-like receptor signaling. Furthermore, by the use of germ-free mouse models, the presence of a gut microbiota was shown to influence the synthesis of endothelial adhesion molecules. Hence, the gut microbiota is increasingly being recognized as an influencing factor of arterial thrombosis and attempts of dietary pre- or probiotic modulation of the commensal microbiota, to reduce cardiovascular risk, are becoming increasingly significant.
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5
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Dabrowski AN, Conrad C, Behrendt U, Shrivastav A, Baal N, Wienhold SM, Hackstein H, N'Guessan PD, Aly S, Reppe K, Suttorp N, Zahlten J. Peptidoglycan Recognition Protein 2 Regulates Neutrophil Recruitment Into the Lungs After Streptococcus pneumoniae Infection. Front Microbiol 2019; 10:199. [PMID: 30837960 PMCID: PMC6389715 DOI: 10.3389/fmicb.2019.00199] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/24/2019] [Indexed: 12/22/2022] Open
Abstract
Peptidoglycan (PGN) recognition proteins (PGLYRPs) are a highly conserved group of host defense proteins in insects and mammals that sense bacterial cell wall PGN and act bactericidally or cleave PGN by amidase function. Streptococcus (S.) pneumoniae is one of the top five killers worldwide and causes, e.g., pneumonia, endocarditis, meningitis and sepsis. S. pneumoniae accounts for approximately 1.5–2 million deaths every year. The risk of antibiotic resistance and a general poor prognosis in young children and elderly people have led to the need for new treatment approaches. To the best of our knowledge, there is no report on the relevance of PGLYRP2 in lung infections. Therefore, we infected mice deficient for PGLYRP2 transnasally with S. pneumoniae and examined the innate immune response in comparison to WT animals. As expected, PGLYRP2-KO animals had to be sacrificed earlier than their WT counterparts, and this was due to higher bacteremia. The higher bacterial load in the PGLYRP2-KO mice was accomplished with lower amounts of proinflammatory cytokines in the lungs. This led to an abolished recruitment of neutrophils into the lungs, the spread of bacteria and the subsequent aggravated course of the disease and early mortality of the PGLYRP2-KO mice. These data suggest a substantial role of PGLYRP2 in the early defense against S. pneumoniae infection, and PGLYRP2 might also affect other infections in the lungs.
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Affiliation(s)
- Alexander N Dabrowski
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Claudia Conrad
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Ulrike Behrendt
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Anshu Shrivastav
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Nelli Baal
- Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
| | - Sandra M Wienhold
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Division of Pulmonary Inflammation, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Holger Hackstein
- Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
| | - Philippe D N'Guessan
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sahar Aly
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Katrin Reppe
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Division of Pulmonary Inflammation, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Norbert Suttorp
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Janine Zahlten
- Department of Infectious Diseases and Respiratory Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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6
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Scholz GM, Heath JE, Aw J, Reynolds EC. Regulation of the Peptidoglycan Amidase PGLYRP2 in Epithelial Cells by Interleukin-36γ. Infect Immun 2018; 86:e00384-18. [PMID: 29914927 PMCID: PMC6105881 DOI: 10.1128/iai.00384-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 06/11/2018] [Indexed: 12/16/2022] Open
Abstract
Interleukin-36 (IL-36) cytokines are important regulators of mucosal homeostasis and inflammation. We have previously established that oral epithelial cells upregulate IL-36γ expression in response to the bacterial pathogen Porphyromonas gingivalis Here, we have established that IL-36γ can stimulate the gene expression of mechanistically distinct antimicrobial proteins, including the peptidoglycan amidase PGLYRP2, in oral epithelial cells (e.g., TIGK cells). PGLYRP2 gene expression was not stimulated by either IL-17 or IL-22, thus demonstrating selectivity in the regulation of PGLYRP2 by IL-36γ. The IL-36γ-inducible expression of PGLYRP2 was shown to be mediated by IRAK1- and p38 mitogen-activated protein (MAP) kinase-dependent signaling. Furthermore, our finding that IL-36γ-inducible PGLYRP2 expression was reduced in proliferating TIGK cells but increased in terminally differentiating cells suggests that control of PGLYRP2 expression is associated with the maturation of the oral epithelium. PGLYRP2 expression in TIGK cells can also be directly stimulated by oral bacteria. However, the extracellular gingipain proteases (Kgp and RgpA/B) produced by P. gingivalis, which are critical virulence factors, can antagonize PGLYRP2 expression. Thus, the expression of IL-36γ by oral epithelial cells in response to P. gingivalis might enable the subsequent autocrine stimulation of PGLYRP2 expression. In summary, our data identify how IL-36γ may promote oral mucosal homeostasis by regulating PGLYRP2 expression.
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Affiliation(s)
- Glen M Scholz
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Jacqueline E Heath
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Jiamin Aw
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Eric C Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
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7
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Abstract
The innate immune system recognizes microbial products using germline-encoded receptors that initiate inflammatory responses to infection. The bacterial cell wall component peptidoglycan is a prime example of a conserved pathogen-associated molecular pattern (PAMP) for which the innate immune system has evolved sensing mechanisms. Peptidoglycan is a direct target for innate immune receptors and also regulates the accessibility of other PAMPs to additional innate immune receptors. Subtle structural modifications to peptidoglycan can influence the ability of the innate immune system to detect bacteria and can allow bacteria to evade or alter host defences. This Review focuses on the mechanisms of peptidoglycan recognition that are used by mammalian cells and discusses new insights into the role of peptidoglycan recognition in inflammation, metabolism, immune homeostasis and disease.
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Affiliation(s)
- Andrea J Wolf
- Research Division of Immunology, Department of Biomedical Sciences, Cedars-Sinai Medical Center
| | - David M Underhill
- Research Division of Immunology, Department of Biomedical Sciences, Cedars-Sinai Medical Center.,Inflammatory Bowel and Immunobiology Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, California 90048, USA
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8
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De Marzi MC, Todone M, Ganem MB, Wang Q, Mariuzza RA, Fernández MM, Malchiodi EL. Peptidoglycan recognition protein-peptidoglycan complexes increase monocyte/macrophage activation and enhance the inflammatory response. Immunology 2015; 145:429-42. [PMID: 25752767 DOI: 10.1111/imm.12460] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 02/19/2015] [Accepted: 02/28/2015] [Indexed: 02/02/2023] Open
Abstract
Peptidoglycan recognition proteins (PGRP) are pattern recognition receptors that can bind or hydrolyse peptidoglycan (PGN). Four human PGRP have been described: PGRP-S, PGRP-L, PGRP-Iα and PGRP-Iβ. Mammalian PGRP-S has been implicated in intracellular destruction of bacteria by polymorphonuclear cells, PGRP-Iα and PGRP-Iβ have been found in keratinocytes and epithelial cells, and PGRP-L is a serum protein that hydrolyses PGN. We have expressed recombinant human PGRP and observed that PGRP-S and PGRP-Iα exist as monomer and disulphide dimer proteins. The PGRP dimers maintain their biological functions. We detected the PGRP-S dimer in human serum and polymorphonuclear cells, from where it is secreted after degranulation; these cells being a possible source of serum PGRP-S. Recombinant PGRP do not act as bactericidal or bacteriostatic agents in the assayed conditions; however, PGRP-S and PGRP-Iα cause slight damage in the bacterial membrane. Monocytes/macrophages increase Staphylococcus aureus phagocytosis in the presence of PGRP-S, PGRP-Iα and PGRP-Iβ. All PGRP bind to monocyte/macrophage membranes and are endocytosed by them. In addition, all PGRP protect cells from PGN-induced apoptosis. PGRP increase THP-1 cell proliferation and enhance activation by PGN. PGRP-S-PGN complexes increase the membrane expression of CD14, CD80 and CD86, and enhance secretion of interleukin-8, interleukin-12 and tumour necrosis factor-α, but reduce interleukin-10, clearly inducing an inflammatory profile.
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Affiliation(s)
- Mauricio C De Marzi
- Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-UBA, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.,Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina.,Instituto de Ecología y Desarrollo Sustentable (INEDES), Luján, Buenos Aires, Argentina
| | - Marcos Todone
- Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-UBA, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.,Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina.,Instituto de Ecología y Desarrollo Sustentable (INEDES), Luján, Buenos Aires, Argentina
| | - María B Ganem
- Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-UBA, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Qian Wang
- W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, MD, USA
| | - Roy A Mariuzza
- W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, MD, USA
| | - Marisa M Fernández
- Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-UBA, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Emilio L Malchiodi
- Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-UBA, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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9
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Wheeler R, Chevalier G, Eberl G, Gomperts Boneca I. The biology of bacterial peptidoglycans and their impact on host immunity and physiology. Cell Microbiol 2014; 16:1014-23. [DOI: 10.1111/cmi.12304] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Revised: 04/14/2014] [Accepted: 04/16/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Richard Wheeler
- Institut Pasteur; Biology and genetics of the bacterial cell wall Unit; Paris 75724 France
- INSERM; Avenir group; Paris 75015 France
| | - Grégoire Chevalier
- Institut Pasteur; Development of Lymphoid Tissues Unit; Paris 75724 France
| | - Gérard Eberl
- Institut Pasteur; Development of Lymphoid Tissues Unit; Paris 75724 France
| | - Ivo Gomperts Boneca
- Institut Pasteur; Biology and genetics of the bacterial cell wall Unit; Paris 75724 France
- INSERM; Avenir group; Paris 75015 France
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10
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Rescigno M. Intestinal microbiota and its effects on the immune system. Cell Microbiol 2014; 16:1004-13. [PMID: 24720613 DOI: 10.1111/cmi.12301] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/13/2014] [Indexed: 12/11/2022]
Abstract
The microbiota colonizes every surface exposed to the external world and in the gut, it plays important roles in physiological functions such as the maturation of the immune system, the degradation of complex food macromolecules and also behaviour. As such, the immune system has developed tools to cohabit with the microbiota, but also to keep it under control. When this control is lost, dysbiosis, i.e. deregulation in bacterial communities, can occur and this can lead to inflammatory disorders, including inflammatory bowel disease, obesity, diabetes and autism. For these reasons, the analysis of the microbiota, its interactions with the host and its composition in disease, have been intensively investigated in the last few years. In this review, we summarize the major findings in the interaction of the microbiota with the host immune system.
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Affiliation(s)
- Maria Rescigno
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
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11
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Philpott DJ, Sorbara MT, Robertson SJ, Croitoru K, Girardin SE. NOD proteins: regulators of inflammation in health and disease. Nat Rev Immunol 2013; 14:9-23. [PMID: 24336102 DOI: 10.1038/nri3565] [Citation(s) in RCA: 456] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Entry of bacteria into host cells is an important virulence mechanism. Through peptidoglycan recognition, the nucleotide-binding oligomerization domain (NOD) proteins NOD1 and NOD2 enable detection of intracellular bacteria and promote their clearance through initiation of a pro-inflammatory transcriptional programme and other host defence pathways, including autophagy. Recent findings have expanded the scope of the cellular compartments monitored by NOD1 and NOD2 and have elucidated the signalling pathways that are triggered downstream of NOD activation. In vivo, NOD1 and NOD2 have complex roles, both during bacterial infection and at homeostasis. The association of alleles that encode constitutively active or constitutively inactive forms of NOD2 with different diseases highlights this complexity and indicates that a balanced level of NOD signalling is crucial for the maintenance of immune homeostasis.
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Affiliation(s)
- Dana J Philpott
- 1] Department of Immunology, University of Toronto, Toronto M5S 1A8, Canada. [2]
| | - Matthew T Sorbara
- 1] Department of Immunology, University of Toronto, Toronto M5S 1A8, Canada. [2]
| | | | - Kenneth Croitoru
- Institute of Medical Science, Department of Medicine, University of Toronto, Toronto M5S 1A8, Canada
| | - Stephen E Girardin
- 1] Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto M5S 1A8, Canada. [2]
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12
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Salem M, Seidelin JB, Rogler G, Nielsen OH. Muramyl dipeptide responsive pathways in Crohn's disease: from NOD2 and beyond. Cell Mol Life Sci 2013; 70:3391-404. [PMID: 23275943 PMCID: PMC11113952 DOI: 10.1007/s00018-012-1246-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 12/12/2012] [Accepted: 12/13/2012] [Indexed: 12/15/2022]
Abstract
Crohn's disease (CD) is one of main disease entities under the umbrella term chronic inflammatory bowel disease. The etiology of CD involves alterations in genetic, microbiological, and immunological factors. This review is devoted to the role of the bacterial wall compound muramyl dipeptide (MDP) for the activation of inflammatory pathways involved in the pathogenesis of CD. The importance of this molecule is underscored by the fact that (1) MDP, which is found in most Gram-negative and -positive bacteria, is able to trigger several immunological responses in the intestinal system, and (2) that alterations in several mediators of the MDP response including-but not restricted to-nucleotide oligomerization domain 2 (NOD2) are associated with CD. The normalization of MDP signaling is one of several important factors that influence the intestinal inflammatory response, a fact which emphasizes the pathogenic importance of MDP signaling for the pathogenesis of CD. The important aspects of NOD2 and non-NOD2 mediated effects of MDP for the development of CD are highlighted, as well as how alterations in these pathways might translate into the development of new therapeutic strategies.
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Affiliation(s)
- Mohammad Salem
- Department of Gastroenterology D, Medical Section, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, 2730 Herlev, Denmark
| | - Jakob Benedict Seidelin
- Department of Gastroenterology D, Medical Section, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, 2730 Herlev, Denmark
- Department of Internal Medicine, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology, Zürich University Hospital, Zurich, Switzerland
| | - Ole Haagen Nielsen
- Department of Gastroenterology D, Medical Section, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, 2730 Herlev, Denmark
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Neonatal immune adaptation of the gut and its role during infections. Clin Dev Immunol 2013; 2013:270301. [PMID: 23737810 PMCID: PMC3659470 DOI: 10.1155/2013/270301] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 04/03/2013] [Indexed: 12/22/2022]
Abstract
The intestinal tract is engaged in a relationship with a dense and complex microbial ecosystem, the microbiota. The establishment of this symbiosis is essential for host physiology, metabolism, and immune homeostasis. Because newborns are essentially sterile, the first exposure to microorganisms and environmental endotoxins during the neonatal period is followed by a crucial sequence of active events leading to immune tolerance and homeostasis. Contact with potent immunostimulatory molecules starts immediately at birth, and the discrimination between commensal bacteria and invading pathogens is essential to avoid an inappropriate immune stimulation and/or host infection. The dysregulation of these tight interactions between host and microbiota can be responsible for important health disorders, including inflammation and sepsis. This review summarizes the molecular events leading to the establishment of postnatal immune tolerance and how pathogens can avoid host immunity and induce neonatal infections and sepsis.
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Role of mouse peptidoglycan recognition protein PGLYRP2 in the innate immune response to Salmonella enterica serovar Typhimurium infection in vivo. Infect Immun 2012; 80:2645-54. [PMID: 22615249 DOI: 10.1128/iai.00168-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Peptidoglycan recognition proteins (PGRPs) are a family of innate pattern recognition molecules that bind bacterial peptidoglycan. While the role of PGRPs in Drosophila innate immunity has been extensively studied, how the four mammalian PGRP proteins (PGLYRP1 to PGLYRP4) contribute to host defense against bacterial pathogens in vivo remains poorly understood. PGLYRP1, PGLYRP3, and PGLYRP4 are directly bactericidal in vitro, whereas PGLYRP2 is an N-acetylmuramyl-L-alanine amidase that cleaves peptidoglycan between the sugar backbone and the peptide stem. Because PGLYRP2 cleaves muramyl peptides detected by host peptidoglycan sensors Nod1 and Nod2, we speculated that PGLYRP2 may act as a modifier of Nod1/Nod2-dependent innate immune responses. We investigated the role of PGLYRP2 in Salmonella enterica serovar Typhimurium-induced colitis, which is regulated by Nod1/Nod2 through the induction of an early Th17 response. PGLYRP2 did not contribute to expression of Th17-associated cytokines, interleukin-22 (IL-22)-dependent antimicrobial proteins, or inflammatory cytokines. However, we found that Pglyrp2-deficient mice displayed significantly enhanced inflammation in the cecum at 72 h postinfection, reflected by increased polymorphonuclear leukocyte (PMN) infiltration and goblet cell depletion. Pglyrp2 expression was also induced in the cecum of Salmonella-infected mice, and expression of green fluorescent protein under control of the Pglyrp2 promoter was increased in discrete populations of intraepithelial lymphocytes. Lastly, Nod2(-/-) Pglyrp2(-/-) mice displayed increased susceptibility to infection at 24 h postinfection compared to Pglyrp2(-/-) mice, which correlated with increased PMN infiltration and submucosal edema. Thus, PGLYRP2 plays a protective role in vivo in the control of S. Typhimurium infection through a Nod1/Nod2-independent mechanism.
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Abstract
Initial recognition of bacteria by the innate immune system is thought to occur primarily by germline-encoded pattern recognition receptors (PRRs). These receptors are present in multiple compartments of host cells and are thus capable of surveying both the intracellular and extracellular milieu for bacteria. It has generally been presumed that the cellular location of these receptors dictates what type of bacteria they respond to: extracellular bacteria being recognized by cell surface receptors, such as certain Toll-like receptors, and bacteria that are capable of breaching the plasma membrane and entering the cytoplasm, being sensed by cytoplasmic receptors, including the Nod-like receptors (NLRs). Increasingly, it is becoming apparent that this is a false dichotomy and that extracellular bacteria can be sensed by cytoplasmic PRRs and this is crucial for controlling the levels of these bacteria. In this review, we discuss the role of two NLRs, Nod1 and Nod2, in the recognition of and response to extracellular bacteria.
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Affiliation(s)
- Thomas B Clarke
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6076, USA
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Sorbara MT, Philpott DJ. Peptidoglycan: a critical activator of the mammalian immune system during infection and homeostasis. Immunol Rev 2011; 243:40-60. [PMID: 21884166 DOI: 10.1111/j.1600-065x.2011.01047.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Peptidoglycan is a conserved structural component of the bacterial cell wall with molecular motifs unique to bacteria. The mammalian immune system takes advantage of these properties and has evolved to recognize this microbial associated molecular pattern. Mammals have four secreted peptidoglycan recognition proteins, PGLYRP-1-4, as well as two intracellular sensors of peptidoglycan, Nod1 and Nod2. Recognition of peptidoglycan is important in initiating and shaping the immune response under both homeostatic and infection conditions. During infection, peptidoglycan recognition drives both cell-autonomous and whole-organism defense responses. Here, we examine recent advances in the understanding of how peptidoglycan recognition shapes mammalian immune responses in these diverse contexts.
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Affiliation(s)
- Matthew T Sorbara
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
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Duerr CU, Hornef MW. The mammalian intestinal epithelium as integral player in the establishment and maintenance of host-microbial homeostasis. Semin Immunol 2011; 24:25-35. [PMID: 22138188 DOI: 10.1016/j.smim.2011.11.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Only one single layer of epithelial cells separates the densely colonized and environmentally exposed intestinal lumen from the largely sterile subepithelial tissue. Together with the overlaying mucus and the subepithelial mucosal immune system the epithelium has evolved to maintain homeostasis in the presence of the enteric microbiota. It also contributes to rapid and efficient antimicrobial host defence in the event of infection with pathogenic microorganisms. Both, epithelial antimicrobial host defence and homeostasis rely on signalling pathways induced by innate immune receptors demonstrating the active role of epithelial cells in the host-microbial interplay. The interaction of epithelial cells with professional immune cells illustrates the integrated function within the mucosal tissue. In the present review we focus on structural and functional changes of the intestinal epithelium during the fetal-neonatal transition and infancy and try to delineate its role in the induction and maintenance of host-microbial homeostasis. We also address factors that impair epithelial functions and may lead to disruption of the mucosal barrier, tissue damage and the development of symptomatic disease.
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Affiliation(s)
- Claudia U Duerr
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Carl-Neuberg Str. 1, D-30625 Hannover, Germany
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Werts C, Rubino S, Ling A, Girardin SE, Philpott DJ. Nod-like receptors in intestinal homeostasis, inflammation, and cancer. J Leukoc Biol 2011; 90:471-82. [PMID: 21653239 DOI: 10.1189/jlb.0411183] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
NLRs have been shown in a number of models to protect against microbial infection through their ability to participate in "pattern recognition" and their triggering of inflammatory pathways to control infection. Over the past few years, however, the role of NLRs, especially Nod1, Nod2, and NLRP3, in intestinal homeostasis has been highlighted. Indeed, these specific NLRs have been implicated in IBD, in particular, the association of Nod2 with CD, yet a clear understanding of how dysfunctional NLR activation leads to aberrant inflammation is still the focus of much investigation. In this review, we will examine how NLRs participate in the maintenance of gut homeostasis and how upset of this regulation can tip the balance toward chronic inflammation and intestinal cancer.
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Affiliation(s)
- Catherine Werts
- Institut Pasteur, Biology and Genetics of Bacterial Cell Wall, Avenir Group INSERM, Paris, France
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