1
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Zhang J, Cruz-Cosme R, Zhang C, Liu D, Tang Q, Zhao RY. Endoplasmic reticulum-associated SARS-CoV-2 ORF3a elicits heightened cytopathic effects despite robust ER-associated degradation. mBio 2024; 15:e0303023. [PMID: 38078754 PMCID: PMC10790703 DOI: 10.1128/mbio.03030-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 11/10/2023] [Indexed: 01/17/2024] Open
Abstract
IMPORTANCE The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has tragically claimed millions of lives through coronavirus disease 2019 (COVID-19), and there remains a critical gap in our understanding of the precise molecular mechanisms responsible for the associated fatality. One key viral factor of interest is the SARS-CoV-2 ORF3a protein, which has been identified as a potent inducer of host cellular proinflammatory responses capable of triggering the catastrophic cytokine storm, a primary contributor to COVID-19-related deaths. Moreover, ORF3a, much like the spike protein, exhibits a propensity for frequent mutations, with certain variants linked to the severity of COVID-19. Our previous research unveiled two distinct types of ORF3a mutant proteins, categorized by their subcellular localizations, setting the stage for a comparative investigation into the functional and mechanistic disparities between these two types of ORF3a variants. Given the clinical significance and functional implications of the natural ORF3a mutations, the findings of this study promise to provide invaluable insights into the potential roles undertaken by these mutant ORF3a proteins in the pathogenesis of COVID-19.
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Affiliation(s)
- Jiantao Zhang
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ruth Cruz-Cosme
- Department of Microbiology, Howard University College of Medicine, Washington, DC, USA
| | - Chenyu Zhang
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Dongxiao Liu
- Department of Microbiology, Howard University College of Medicine, Washington, DC, USA
| | - Qiyi Tang
- Department of Microbiology, Howard University College of Medicine, Washington, DC, USA
| | - Richard Y. Zhao
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Institute of Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Research & Development Service, VA Maryland Health Care System, Baltimore, Maryland, USA
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2
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Iyer K, Erkert L, Becker C. Know your neighbors: microbial recognition at the intestinal barrier and its implications for gut homeostasis and inflammatory bowel disease. Front Cell Dev Biol 2023; 11:1228283. [PMID: 37519301 PMCID: PMC10375050 DOI: 10.3389/fcell.2023.1228283] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 07/07/2023] [Indexed: 08/01/2023] Open
Abstract
Intestinal epithelial cells (IECs) perform several physiological and metabolic functions at the epithelial barrier. IECs also play an important role in defining the overall immune functions at the mucosal region. Pattern recognition receptors (PRRs) on the cell surface and in other cellular compartments enable them to sense the presence of microbes and microbial products in the intestinal lumen. IECs are thus at the crossroads of mediating a bidirectional interaction between the microbial population and the immune cells present at the intestinal mucosa. This communication between the microbial population, the IECs and the underlying immune cells has a profound impact on the overall health of the host. In this review, we focus on the various PRRs present in different cellular compartments of IECs and discuss the recent developments in the understanding of their role in microbial recognition. Microbial recognition and signaling at the epithelial barrier have implications in the maintenance of intestinal homeostasis, epithelial barrier function, maintenance of commensals, and the overall tolerogenic function of PRRs in the gut mucosa. We also highlight the role of an aberrant microbial sensing at the epithelial barrier in the pathogenesis of inflammatory bowel disease (IBD) and the development of colorectal cancer.
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Affiliation(s)
- Krishna Iyer
- Department of Medicine 1, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Evergrande Center for Immunologic Diseases, Harvard Medical School and Brigham and Women’s Hospital, Boston, MA, United States
| | - Lena Erkert
- Department of Medicine 1, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Becker
- Department of Medicine 1, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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3
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Taban Q, Ahmad SM, Mumtaz PT, Bhat B, Haq E, Magray S, Saleem S, Shabir N, Muhee A, Kashoo ZA, Zargar MH, Malik AA, Ganai NA, Shah RA. Scavenger receptor B1 facilitates the endocytosis of Escherichia coli via TLR4 signaling in mammary gland infection. Cell Commun Signal 2023; 21:3. [PMID: 36604713 PMCID: PMC9813905 DOI: 10.1186/s12964-022-01014-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/11/2022] [Indexed: 01/06/2023] Open
Abstract
SCARB1 belongs to class B of Scavenger receptors (SRs) that are known to be involved in binding and endocytosis of various pathogens. SRs have emerging role in regulating innate immunity and host-pathogen interactions by acting in co-ordination with Toll-like receptors.Query Little is known about the function of SCARB1 in milk-derived mammary epithelial cells (MECs). This study reports the role of SCARB1 in infection and its potential association in TLR4 signaling on bacterial challenge in Goat mammary epithelial cells (GMECs). The novelty in the establishment of MEC culture lies in the method that aims to enhance the viability of the cells with intact characteristics upto a higher passage number. We represent MEC culture to be used as a potential infection model for deeper understanding of animal physiology especially around the mammary gland. On E.coli challenge the expression of SCARB1 was significant in induced GMECs at 6 h. Endoribonuclease-esiRNA based silencing of SCARB1 affects the expression of TLR4 and its pathways i.e. MyD88 and TRIF pathways on infection. Knockdown also affected the endocytosis of E.coli in GMECs demonstrating that E.coli uses SCARB1 function to gain entry in cells. Furthermore, we predict 3 unique protein structures of uncharacterized SCARB1 (Capra hircus) protein. Overall, we highlight SCARB1 as a main participant in host defence and its function in antibacterial advances to check mammary gland infections. Video Abstract.
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Affiliation(s)
- Qamar Taban
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India ,grid.412997.00000 0001 2294 5433Department of Biotechnology, University of Kashmir, Hazratbal Srinagar, Jammu and Kashmir India
| | - Syed Mudasir Ahmad
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Peerzada Tajamul Mumtaz
- grid.24434.350000 0004 1937 0060Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, USA
| | - Basharat Bhat
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Ehtishamul Haq
- grid.412997.00000 0001 2294 5433Department of Biotechnology, University of Kashmir, Hazratbal Srinagar, Jammu and Kashmir India
| | - Suhail Magray
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Sahar Saleem
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Nadeem Shabir
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Amatul Muhee
- grid.444725.40000 0004 0500 6225Department of Clinical Veterinary Medicine, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Zahid Amin Kashoo
- grid.444725.40000 0004 0500 6225Department of Veterinary Microbiology & Immunology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Mahrukh Hameed Zargar
- grid.414739.c0000 0001 0174 2901Department of Advanced Centre for Human Genetics, Sher-I-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir India
| | - Abrar A. Malik
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Nazir A. Ganai
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
| | - Riaz A. Shah
- grid.444725.40000 0004 0500 6225Division of Animal Biotechnology, Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, FV.Sc and A.H, Shuhama, Jammu and Kashmir India
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4
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Dhuppar S, Murugaiyan G. miRNA effects on gut homeostasis: therapeutic implications for inflammatory bowel disease. Trends Immunol 2022; 43:917-931. [PMID: 36220689 PMCID: PMC9617792 DOI: 10.1016/j.it.2022.09.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/05/2022] [Accepted: 09/11/2022] [Indexed: 01/12/2023]
Abstract
Inflammatory bowel disease (IBD) spans a range of chronic conditions affecting the gastrointestinal (GI) tract, which are marked by intermittent flare-ups and remissions. IBD results from microbial dysbiosis or a defective mucosal barrier in the gut that triggers an inappropriate immune response in a genetically susceptible person, altering the immune-microbiome axis. In this review, we discuss the regulatory roles of miRNAs, small noncoding RNAs with gene regulatory functions, in the stability and maintenance of the gut immune-microbiome axis, and detail the challenges and recent advances in the use of miRNAs as putative therapeutic agents for treating IBD.
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Affiliation(s)
- Shivnarayan Dhuppar
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Current address: Centre for Business Innovation, The Indian School of Business, Hyderabad 500111, India
| | - Gopal Murugaiyan
- Ann Romney Center for Neurological Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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5
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Hailemariam D, Lam TH, Dervishi E, Zwierzchowski G, Wishart DS, Ametaj BN. Combination of mouse prion protein with detoxified lipopolysaccharide triggers colon genes related to inflammatory, antibacterial, and apoptotic responses. Res Vet Sci 2022; 144:98-107. [DOI: 10.1016/j.rvsc.2022.01.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 12/03/2021] [Accepted: 01/20/2022] [Indexed: 10/19/2022]
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6
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Su G, Luo Y, Chen D, Yu B, He J. NF-κB-dependent induction of porcine β-defensin 114 regulates intestinal epithelium homeostasis. Int J Biol Macromol 2021; 192:241-249. [PMID: 34619281 DOI: 10.1016/j.ijbiomac.2021.09.163] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 11/29/2022]
Abstract
Intestinal epithelial cells (IECs) offer a primary physical barrier against commensal and pathogenic microorganisms in the gastrointestine. However, the influence of IECs on the development and regulation of mucosal immunity to infection is unknown. Here, we show that the porcine β-defensin 114 (PBD114) is an endotoxin-responsive gene expressed in IECs. Analysis on expression profiling of PBD114 gene using an infected porcine model and IPEC-J2 cells unveiled a pattern of induction in response to stimulation of various toll-like receptors (TLRs). By means of promoter analysis, PBD114 was found to be a NF-κB-dependent gene. Importantly, PBD114 suppresses endotoxin-induced inflammation and apoptosis in IECs through downregulation of two critical inflammation-associated signaling proteins, NF-kappa-B inhibitor alpha (IkB-α) and extracellular signal-regulated kinase1/2 (ERK1/2). PBD114 also suppresses inflammation and IEC apoptosis in mice exposed to bacterial endotoxins. Thus, we propose that TLR-activated NF-kB rapidly increases the expression of PBD114 that operates a feedback control of the NF-kB-dependent inflammation. The NF-kB-dependent induction of PBD114 may be a key event through which the mammalian host maintains intestinal epithelium homeostasis in response to various infections or diseases.
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Affiliation(s)
- Guoqi Su
- Institute of Animal Nutrition, Sichuan Agricultural University, Sichuan Province, Chengdu 611130, PR China; Chongqing Academy of Animal Sciences, Chongqing 402460, PR China
| | - Yuheng Luo
- Institute of Animal Nutrition, Sichuan Agricultural University, Sichuan Province, Chengdu 611130, PR China; Key Laboratory of Animal Disease-resistant Nutrition, Sichuan Province, Chengdu 611130, PR China
| | - Daiwen Chen
- Institute of Animal Nutrition, Sichuan Agricultural University, Sichuan Province, Chengdu 611130, PR China; Key Laboratory of Animal Disease-resistant Nutrition, Sichuan Province, Chengdu 611130, PR China
| | - Bing Yu
- Institute of Animal Nutrition, Sichuan Agricultural University, Sichuan Province, Chengdu 611130, PR China; Key Laboratory of Animal Disease-resistant Nutrition, Sichuan Province, Chengdu 611130, PR China
| | - Jun He
- Institute of Animal Nutrition, Sichuan Agricultural University, Sichuan Province, Chengdu 611130, PR China; Key Laboratory of Animal Disease-resistant Nutrition, Sichuan Province, Chengdu 611130, PR China.
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7
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Hausmann A, Felmy B, Kunz L, Kroon S, Berthold DL, Ganz G, Sandu I, Nakamura T, Zangger NS, Zhang Y, Dolowschiak T, Fattinger SA, Furter M, Müller-Hauser AA, Barthel M, Vlantis K, Wachsmuth L, Kisielow J, Tortola L, Heide D, Heikenwälder M, Oxenius A, Kopf M, Schroeder T, Pasparakis M, Sellin ME, Hardt WD. Intercrypt sentinel macrophages tune antibacterial NF-κB responses in gut epithelial cells via TNF. J Exp Med 2021; 218:e20210862. [PMID: 34529751 PMCID: PMC8480669 DOI: 10.1084/jem.20210862] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/21/2021] [Accepted: 08/25/2021] [Indexed: 12/14/2022] Open
Abstract
Intestinal epithelial cell (IEC) NF-κB signaling regulates the balance between mucosal homeostasis and inflammation. It is not fully understood which signals tune this balance and how bacterial exposure elicits the process. Pure LPS induces epithelial NF-κB activation in vivo. However, we found that in mice, IECs do not respond directly to LPS. Instead, tissue-resident lamina propria intercrypt macrophages sense LPS via TLR4 and rapidly secrete TNF to elicit epithelial NF-κB signaling in their immediate neighborhood. This response pattern is relevant also during oral enteropathogen infection. The macrophage-TNF-IEC axis avoids responses to luminal microbiota LPS but enables crypt- or tissue-scale epithelial NF-κB responses in proportion to the microbial threat. Thereby, intercrypt macrophages fulfill important sentinel functions as first responders to Gram-negative microbes breaching the epithelial barrier. The tunability of this crypt response allows the induction of defense mechanisms at an appropriate scale according to the localization and intensity of microbial triggers.
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Affiliation(s)
- Annika Hausmann
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Boas Felmy
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Leo Kunz
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule Zurich, Basel, Switzerland
| | - Sanne Kroon
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Dorothée Lisa Berthold
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Giverny Ganz
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Ioana Sandu
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Toshihiro Nakamura
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Nathan Sébastien Zangger
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Yang Zhang
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule Zurich, Basel, Switzerland
| | - Tamas Dolowschiak
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Stefan Alexander Fattinger
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Markus Furter
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Anna Angelika Müller-Hauser
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Manja Barthel
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Katerina Vlantis
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Laurens Wachsmuth
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Jan Kisielow
- Institute of Molecular Health Sciences, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Luigi Tortola
- Institute of Molecular Health Sciences, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Danijela Heide
- Division of Chronic Inflammation and Cancer, German Cancer Research Center, Heidelberg, Germany
| | - Mathias Heikenwälder
- Division of Chronic Inflammation and Cancer, German Cancer Research Center, Heidelberg, Germany
| | - Annette Oxenius
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Manfred Kopf
- Institute of Molecular Health Sciences, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
| | - Timm Schroeder
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule Zurich, Basel, Switzerland
| | - Manolis Pasparakis
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Mikael Erik Sellin
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
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8
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Hu X, Fatima S, Chen M, Xu K, Huang C, Gong RH, Su T, Wong HLX, Bian Z, Kwan HY. Toll-like receptor 4 is a master regulator for colorectal cancer growth under high-fat diet by programming cancer metabolism. Cell Death Dis 2021; 12:791. [PMID: 34385421 PMCID: PMC8360949 DOI: 10.1038/s41419-021-04076-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 12/12/2022]
Abstract
Although high-fat diet (HFD) has been implicated in the development of colorectal cancer (CRC), the critical signaling molecule that mediates the cancer growth is not well-defined. Identifying the master regulator that controls CRC growth under HFD can facilitate the development of effective therapeutics for the cancer treatment. In this study, the global lipidomics and RNA sequencing data show that, in the tumor tissues of CRC-bearing mouse models, HFD not only increases tumor weight, but also the palmitic acid level and TLR4 expression, which are reduced when HFD is replaced by control diet. These concomitant changes suggest the roles of palmitic acid and TLR4 in CRC growth. Subsequent studies show that palmitic acid regulates TLR4 expression in PU.1-dependent manner. Knockdown of PU.1 or mutations of PU.1-binding site on TLR4 promoter abolish the palmitic acid-increased TLR4 expression. The role of palmitic acid/PU.1/TLR4 axis in CRC growth is further examined in cell model and animal models that are fed either HFD or palmitic acid-rich diet. More importantly, iTRAQ proteomics data show that knockdown of TLR4 changes the metabolic enzyme profiles in the tumor tissues, which completely abolish the HFD-enhanced ATP production and cancer growth. Our data clearly demonstrate that TLR4 is a master regulator for CRC growth under HFD by programming cancer metabolism.
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Affiliation(s)
- Xianjing Hu
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Sarwat Fatima
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Minting Chen
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Keyang Xu
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Chunhua Huang
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Rui-Hong Gong
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Tao Su
- International Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, 510006, China
| | - Hoi Leong Xavier Wong
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Zhaoxiang Bian
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China.
| | - Hiu Yee Kwan
- Centre for Cancer and Inflammation Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China.
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9
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Holani R, Babbar A, Blyth GAD, Lopes F, Jijon H, McKay DM, Hollenberg MD, Cobo ER. Cathelicidin-mediated lipopolysaccharide signaling via intracellular TLR4 in colonic epithelial cells evokes CXCL8 production. Gut Microbes 2020; 12:1785802. [PMID: 32658599 PMCID: PMC7524372 DOI: 10.1080/19490976.2020.1785802] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We hypothesized that the antimicrobial peptide cathelicidin has a physiological role in regulating gut inflammatory homeostasis. We determined that cathelicidin synergizes with LPS to facilitate its internalization and signaling via endosomic TLR4 in colonic epithelium, evoking synthesis of the human neutrophil chemoattractant, CXCL8 (or murine homolog, CXCL1). Interaction of cathelicidin with LPS in the control of CXCL8/CXCL1 synthesis was assessed in human colon epithelial cells, murine colonoids and cathelicidin-null mice (Camp-/- ). Mechanistically, human cathelicidin (LL-37), as an extracellular complex with LPS, interacted with lipid raft-associated GM1 gangliosides to internalize and activate intracellular TLR4. Two signaling pathways converged on CXCL8/CXCL1 production: (1) a p38MAPK-dependent pathway regulated by Src-EGFR kinases; and, (2) a p38MAPK-independent, NF-κB-dependent pathway, regulated by MEK1/2-MAPK. Increased cathelicidin-dependent CXCL8 secretion in the colonic mucosa activated human blood-derived neutrophils. These cathelicidin effects occurred in vitro at concentrations well below those needed for microbicidal function. The important immunomodulatory role of cathelicidins was evident in cathelicidin-null/Camp-/- mice, which had diminished colonic CXCL1 secretion, decreased neutrophil recruitment-activation and reduced bacterial clearance when challenged with the colitis-inducing murine pathogen, Citrobacter rodentium. We conclude that in addition to its known microbicidal action, cathelicidin has a unique pathogen-sensing role, facilitating LPS-mediated intestinal responses, including the production of CXCL8/CXCL1 that would contribute to an integrated tissue response to recruit neutrophils during colitis.
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Affiliation(s)
- Ravi Holani
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Anshu Babbar
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Graham A. D. Blyth
- Microbiology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Fernando Lopes
- Institute of Parasitology, McGill University, Montreal, Canada
| | - Humberto Jijon
- Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Derek M. McKay
- Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Morley D. Hollenberg
- Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Eduardo R. Cobo
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada,CONTACT Eduardo R. Cobo Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, ABT2N 4N1, Canada
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10
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Oh C, Verma A, Aachoui Y. Caspase-11 Non-canonical Inflammasomes in the Lung. Front Immunol 2020; 11:1895. [PMID: 32973786 PMCID: PMC7472987 DOI: 10.3389/fimmu.2020.01895] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 07/14/2020] [Indexed: 12/27/2022] Open
Abstract
The airway epithelium and underlying innate immune cells comprise the first line of host defense in the lung. They recognize pathogen-associated molecular patterns (PAMPs) using membrane-bound receptors, as well as cytosolic receptors such as inflammasomes. Inflammasomes activate inflammatory caspases, which in turn process and release the inflammatory cytokines IL-1β and IL-18. Additionally, inflammasomes trigger a form of lytic cell death termed pyroptosis. One of the most important inflammasomes at the host-pathogen interface is the non-canonical caspase-11 inflammasome that responds to LPS in the cytosol. Caspase-11 is important in defense against Gram-negative pathogens, and can drive inflammatory diseases such as LPS-induced sepsis. However, pathogens can employ evasive strategies to minimize or evade host caspase-11 detection. In this review, we present a comprehensive overview of the function of the non-canonical caspase-11 inflammasome in sensing of cytosolic LPS, and its mechanism of action with particular emphasis in the role of caspase-11 in the lung. We also explore some of the strategies pathogens use to evade caspase-11.
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Affiliation(s)
- Changhoon Oh
- Department of Microbiology and Immunology, Center for Microbial Pathogenesis and Host Responses, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Ambika Verma
- Department of Microbiology and Immunology, Center for Microbial Pathogenesis and Host Responses, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Youssef Aachoui
- Department of Microbiology and Immunology, Center for Microbial Pathogenesis and Host Responses, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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11
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Bruning EE, Coller JK, Wardill HR, Bowen JM. Site-specific contribution of Toll-like receptor 4 to intestinal homeostasis and inflammatory disease. J Cell Physiol 2020; 236:877-888. [PMID: 32730645 DOI: 10.1002/jcp.29976] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 07/03/2020] [Accepted: 07/06/2020] [Indexed: 12/12/2022]
Abstract
Toll-like receptor 4 (TLR4) is a highly conserved protein of innate immunity, responsible for the regulation and maintenance of homeostasis, as well as immune recognition of external and internal ligands. TLR4 is expressed on a variety of cell types throughout the gastrointestinal tract, including on epithelial and immune cell populations. In a healthy state, epithelial cell expression of TLR4 greatly assists in homeostasis by shaping the host microbiome, promoting immunoglobulin A production, and regulating follicle-associated epithelium permeability. In contrast, immune cell expression of TLR4 in healthy states is primarily centred on the maturation of dendritic cells in response to stimuli, as well as adequately priming the adaptive immune system to fight infection and promote immune memory. Hence, in a healthy state, there is a clear distinction in the site-specific roles of TLR4 expression. Similarly, recent research has indicated the importance of site-specific TLR4 expression in inflammation and disease, particularly the impact of epithelial-specific TLR4 on disease progression. However, the majority of evidence still remains ambiguous for cell-specific observations, with many studies failing to provide the distinction of epithelial versus immune cell expression of TLR4, preventing specific mechanistic insight and greatly impacting the translation of results. The following review provides a critical overview of the current understanding of site-specific TLR4 activity and its contribution to intestinal/immune homeostasis and inflammatory diseases.
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Affiliation(s)
- Elise E Bruning
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - Janet K Coller
- Discipline of Pharmacology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - Hannah R Wardill
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia.,Department of Paediatric Oncology/Haematology, The University of Groningen (University Medical Centre Groningen), Groningen, The Netherlands
| | - Joanne M Bowen
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
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12
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Yue S, Wang Z, Wang L, Peng Q, Xue B. Transcriptome Functional Analysis of Mammary Gland of Cows in Heat Stress and Thermoneutral Condition. Animals (Basel) 2020; 10:ani10061015. [PMID: 32532099 PMCID: PMC7341491 DOI: 10.3390/ani10061015] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 12/18/2022] Open
Abstract
Simple Summary The current study employed RNA-seq technology to analyze the impact of heat stress on the whole transcript sequencing profile in the mammary glands of lactating Holstein dairy cows. In the findings of the current study, heat stress downregulated the expression of casein genes, which resulted in a decrease in milk production. Moreover, heat stress upregulated the gene expression of HSPA1A and HSP90B1, while it downregulated the expression of immune response-related genes that resulted in a reduction in milk yield. Furthermore, there was an increased synthesis of heat shock proteins and unfolded proteins that could reduce the availability of circulating amino acids for milk protein synthesis. The findings of the current experiment may help to explore the impact of heat stress on immune function, milk production, and milk protein synthesis in cows. Abstract Heat stress (HS) exerts significant effects on the production of dairy animals through impairing health and biological functions. However, the molecular mechanisms related to the effect of HS on dairy cow milk production are still largely unknown. The present study employed an RNA-sequencing approach to explore the molecular mechanisms associated with a decline in milk production by the functional analysis of differentially expressed genes (DEGs) in mammary glands of cows exposed to HS and non-heat-stressed cows. The results of the current study reveal that HS increases the rectal temperature and respiratory rate. Cows under HS result in decreased bodyweight, dry matter intake (DMI), and milk yield. In the current study, a total of 213 genes in experimental cow mammary glands was identified as being differentially expressed by DEGs analysis. Among identified genes, 89 were upregulated, and 124 were downregulated. Gene Ontology functional analysis found that biological processes, such as immune response, chaperone-dependent refolding of protein, and heat shock protein binding activity, were notably affected by HS. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis found that almost all of the top-affected pathways were related to immune response. Under HS, the expression of heat shock protein 90 kDa beta I (HSP90B1) and heat shock 70 kDa protein 1A was upregulated, while the expression of bovine lymphocyte antigen (BoLA) and histocompatibility complex, class II, DRB3 (BoLA-DRB3) was downregulated. We further explored the effects of HS on lactation-related genes and pathways and found that HS significantly downregulated the casein genes. Furthermore, HS increased the expression of phosphorylation of mammalian target of rapamycin, cytosolic arginine sensor for mTORC1 subunit 2 (CASTOR2), and cytosolic arginine sensor for mTORC1 subunit 1 (CASTOR1), but decreased the phosphorylation of Janus kinase-2, a signal transducer and activator of transcription factor-5. Based on the findings of DMI, milk yield, casein gene expression, and the genes and pathways identified by functional annotation analysis, it is concluded that HS adversely affects the immune function of dairy cows. These results will be beneficial to understand the underlying mechanism of reduced milk yield in HS cows.
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13
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Thoo L, Noti M, Krebs P. Keep calm: the intestinal barrier at the interface of peace and war. Cell Death Dis 2019; 10:849. [PMID: 31699962 PMCID: PMC6838056 DOI: 10.1038/s41419-019-2086-z] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/11/2019] [Accepted: 10/23/2019] [Indexed: 12/19/2022]
Abstract
Epithelial barriers have to constantly cope with both harmless and harmful stimuli. The epithelial barrier therefore serves as a dynamic and not static wall to safeguard its proper physiological function while ensuring protection. This is achieved through multiple defence mechanisms involving various cell types - epithelial and non-epithelial - that work in an integrated manner to build protective barriers at mucosal sites. Damage may nevertheless occur, due to pathogens, physical insults or dysregulated immune responses, which trigger a physiologic acute or a pathologic chronic inflammatory cascade. Inflammation is often viewed as a pathological condition, particularly due to the increasing prevalence of chronic inflammatory (intestinal) diseases. However, inflammation is also necessary for wound healing. The aetiology of chronic inflammatory diseases is incompletely understood and identification of the underlying mechanisms would reveal additional therapeutic approaches. Resolution is an active host response to end ongoing inflammation but its relevance is under-appreciated. Currently, most therapies aim at dampening inflammation at damaged mucosal sites, yet these approaches do not efficiently shut down the inflammation process nor repair the epithelial barrier. Therefore, future treatment strategies should also promote the resolution phase. Yet, the task of repairing the barrier can be an arduous endeavour considering its multiple integrated layers of defence - which is advantageous for damage prevention but becomes challenging to repair at multiple levels. In this review, using the intestines as a model epithelial organ and barrier paradigm, we describe the consequences of chronic inflammation and highlight the importance of the mucosae to engage resolving processes to restore epithelial barrier integrity and function. We further discuss the contribution of pre-mRNA alternative splicing to barrier integrity and intestinal homeostasis. Following discussions on current open questions and challenges, we propose a model in which resolution of inflammation represents a key mechanism for the restoration of epithelial integrity and function.
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Affiliation(s)
- Lester Thoo
- Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Mario Noti
- Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.,Department of Gastro-Intestinal Health, Immunology, Nestlé Institute of Health Sciences, Nestlé Research, Lausanne, Switzerland
| | - Philippe Krebs
- Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.
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14
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Patoughi M, Ghafouri-Fard S, Arsang-Jang S, Taheri M. GAS8 and its naturally occurring antisense RNA as biomarkers in multiple sclerosis. Immunobiology 2019; 224:560-564. [DOI: 10.1016/j.imbio.2019.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/07/2019] [Accepted: 04/09/2019] [Indexed: 12/23/2022]
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15
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Liman N, Alan E, Apaydın N. The expression and localization of Toll-like receptors 2, 4, 5 and 9 in the epididymis and vas deferens of a adult tom cats. Theriogenology 2019; 128:62-73. [PMID: 30743105 DOI: 10.1016/j.theriogenology.2019.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 11/18/2022]
Abstract
Toll-like receptors (TLRs) are important molecules, which provide protection against infections of the reproductive tract. This study demonstrates for the first time the expression and localization patterns of TLRs in the caput, corpus and cauda segments of the epididymal duct (ED) and the vas deferens (VD) of adult domestic cats using immunohistochemistry and western blotting. While immunoblot analyses revealed relatively similar protein levels for TLRs 2, 4, 5, and 9 in three segments of the ED, the protein levels of TLR2 and TLR4 in the VD were found to be significantly higher than those measured in the ED segments (P < 0.05). On the other hand, immunostaining showed that TLRs exhibited regional- and cell-specific localization patterns. TLR2 and TLR5 were immunolocalized to the nucleus and cytoplasm of the principal cells in all ducts. TLR4 was restricted to the stereocilia, and TLR9 was located in the cytoplasm of the principal cells. Narrow cells displayed positive immunoreactions for TLR4 and TLR5. The basal cells of the different ED segments were positive for all four TLRs. TLR2, TLR5 and TLR9 were detected in the cytoplasmic droplets of the spermatozoa. TLR4 and TLR9 were detected along the entire length of the sperm tail, whilst TLR2 and TLR5 were absent in the midpiece. TLR2 and TLR5 were also detected in the equatorial segment of the sperm head. These results suggest that TLR2, TLR4, TLR5 and TLR9 are important not only for the protection of the ED, VD and spermatozoa but also for the maturation and storage of spermatozoa in the ED and VD, respectively.
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Affiliation(s)
- Narin Liman
- Department of Histology and Embryology, Faculty of Veterinary Medicine, Erciyes University, 38039, Kayseri, Turkey.
| | - Emel Alan
- Department of Histology and Embryology, Faculty of Veterinary Medicine, Erciyes University, 38039, Kayseri, Turkey
| | - Nusret Apaydın
- Department of Surgery, Faculty of Veterinary Medicine, Erciyes University, 38039, Kayseri, Turkey
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16
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Gingival Epithelial Cell Recognition of Lipopolysaccharide. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1197:55-67. [DOI: 10.1007/978-3-030-28524-1_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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17
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Farquhar MJ, McCluskey E, Staunton R, Hughes KR, Coltherd JC. Characterisation of a canine epithelial cell line for modelling the intestinal barrier. Altern Lab Anim 2018; 46:115-132. [PMID: 30022673 DOI: 10.1177/026119291804600304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Little is known about how food interacts with the intestinal epithelium during the digestion process. However, it is known that ingredients in food can modulate the intestinal barrier, and have the potential to disrupt homeostasis of the gut. Here, we characterise a conditionally immortalised canine intestinal epithelial cell (cIEC) line for use in in vitro assays, to assess the effect of food ingredients on intestinal barrier function, permeability, cell health, and inflammation. Microscopy and flow cytometry confirmed that cIECs had a phenotype consistent with those of epithelial origin, and were able to differentiate to mature enterocytes. The cIECs also formed a monolayer when grown on Transwell® inserts, producing functional tight junctions between the cells. In contrast to the human-derived Caco-2 cell line, transepithelial electrical resistance (TEER) was increased in cIECs in response to two different raw ingredients. The exposure of cIECs to known inflammatory stimuli and raw ingredients induced the nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-?B). This work demonstrates the value of a unique cIEC in vitro model to study the effects of food ingredients on canine intestinal function and health, and supports continued efforts to reduce and refine the use of animals in scientific research.
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Affiliation(s)
| | - Emma McCluskey
- WALTHAM Centre for Pet Nutrition, Waltham on the Wolds, Leicestershire, U
| | - Ruth Staunton
- WALTHAM Centre for Pet Nutrition, Waltham on the Wolds, Leicestershire, U
| | - Kevin R Hughes
- WALTHAM Centre for Pet Nutrition, Waltham on the Wolds, Leicestershire, U
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18
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Price AE, Shamardani K, Lugo KA, Deguine J, Roberts AW, Lee BL, Barton GM. A Map of Toll-like Receptor Expression in the Intestinal Epithelium Reveals Distinct Spatial, Cell Type-Specific, and Temporal Patterns. Immunity 2018; 49:560-575.e6. [PMID: 30170812 PMCID: PMC6152941 DOI: 10.1016/j.immuni.2018.07.016] [Citation(s) in RCA: 212] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/21/2018] [Accepted: 07/26/2018] [Indexed: 12/13/2022]
Abstract
Signaling by Toll-like receptors (TLRs) on intestinal epithelial cells (IECs) is critical for intestinal homeostasis. To visualize epithelial expression of individual TLRs in vivo, we generated five strains of reporter mice. These mice revealed that TLR expression varied dramatically along the length of the intestine. Indeed, small intestine (SI) IECs expressed low levels of multiple TLRs that were highly expressed by colonic IECs. TLR5 expression was restricted to Paneth cells in the SI epithelium. Intestinal organoid experiments revealed that TLR signaling in Paneth cells or colonic IECs induced a core set of host defense genes, but this set did not include antimicrobial peptides, which instead were induced indirectly by inflammatory cytokines. This comprehensive blueprint of TLR expression and function in IECs reveals unexpected diversity in the responsiveness of IECs to microbial stimuli, and together with the associated reporter strains, provides a resource for further study of innate immunity.
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Affiliation(s)
- April E Price
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Kiarash Shamardani
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Kyler A Lugo
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jacques Deguine
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Allison W Roberts
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Bettina L Lee
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Gregory M Barton
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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19
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Pardo-Camacho C, González-Castro AM, Rodiño-Janeiro BK, Pigrau M, Vicario M. Epithelial immunity: priming defensive responses in the intestinal mucosa. Am J Physiol Gastrointest Liver Physiol 2018; 314:G247-G255. [PMID: 29146676 DOI: 10.1152/ajpgi.00215.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
As the largest interface between the outside and internal milieu, the intestinal epithelium constitutes the first structural component facing potential luminal threats to homeostasis. This single-cell layer is the epicenter of a tightly regulated communication network between external and internal factors that converge to prime defensive responses aimed at limiting antigen penetration and the maintenance of intestinal barrier function. The defensive role developed by intestinal epithelial cells (IEC) relies largely on the variety of receptors they express at both extracellular (apical and basolateral) and intracellular compartments, and the capacity of IEC to communicate with immune and nervous systems. IEC recognize pathogen-associated molecules by innate receptors that promote the production of mucus, antimicrobial substances, and immune mediators. Epithelial cells are key to oral tolerance maintenance and also participate in adaptive immunity through the expression of immunoglobulin (Ig) receptors and by promoting local Ig class switch recombination. In IEC, different types of antigens can be sensed by multiple immune receptors that share signaling pathways to assure effective responses. Regulated defensive activity maintains intestinal homeostasis, whereas a breakdown in the control of epithelial immunity can increase the intestinal passage of luminal content and microbial invasion, leading to inflammation and tissue damage. In this review, we provide an updated overview of the type of immune receptors present in the human intestinal epithelium and the responses generated to promote effective barrier function and maintain mucosal homeostasis.
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Affiliation(s)
- Cristina Pardo-Camacho
- Laboratory of Translational Mucosal Immunology, Digestive Diseases Research Unit, Vall d'Hebron Institut de Recerca , Barcelona , Spain.,Department of Gastroenterology, Hospital Universitari Vall d'Hebron , Barcelona , Spain.,Facultat de Medicina, Universitat Autònoma de Barcelona , Barcelona , Spain
| | - Ana M González-Castro
- Laboratory of Translational Mucosal Immunology, Digestive Diseases Research Unit, Vall d'Hebron Institut de Recerca , Barcelona , Spain.,Department of Gastroenterology, Hospital Universitari Vall d'Hebron , Barcelona , Spain.,Facultat de Medicina, Universitat Autònoma de Barcelona , Barcelona , Spain
| | - Bruno K Rodiño-Janeiro
- Laboratory of Neuro-Immuno-Gastroenterology Group, Digestive Diseases Research Unit, Vall d'Hebron Institut de Recerca , Barcelona , Spain.,Department of Gastroenterology, Hospital Universitari Vall d'Hebron , Barcelona , Spain.,Facultat de Medicina, Universitat Autònoma de Barcelona , Barcelona , Spain
| | - Marc Pigrau
- Laboratory of Neuro-Immuno-Gastroenterology Group, Digestive Diseases Research Unit, Vall d'Hebron Institut de Recerca , Barcelona , Spain.,Department of Gastroenterology, Hospital Universitari Vall d'Hebron , Barcelona , Spain.,Facultat de Medicina, Universitat Autònoma de Barcelona , Barcelona , Spain
| | - María Vicario
- Laboratory of Translational Mucosal Immunology, Digestive Diseases Research Unit, Vall d'Hebron Institut de Recerca , Barcelona , Spain.,Department of Gastroenterology, Hospital Universitari Vall d'Hebron , Barcelona , Spain.,Facultat de Medicina, Universitat Autònoma de Barcelona , Barcelona , Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas , Madrid , Spain
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20
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Basic M, Buettner M, Keubler LM, Smoczek A, Bruesch I, Buchheister S, Bleich A. Loss of CD14 leads to disturbed epithelial-B cell crosstalk and impairment of the intestinal barrier after E. coli Nissle monoassociation. Sci Rep 2018; 8:719. [PMID: 29335601 PMCID: PMC5768714 DOI: 10.1038/s41598-017-19062-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 12/19/2017] [Indexed: 02/06/2023] Open
Abstract
The TLR4 co-receptor CD14 was identified as an IBD candidate gene. Here, its influence on the intestinal barrier was addressed utilizing E. coli Nissle (EcN), which induces severe inflammation in germfree TLR4-/- mice. After monoassociation, EcN was detected in spleens and livers of TLR4-/- and CD14-/- but not wildtype mice. Barrier impairment was characterized by increased apoptosis and decreased epithelial junction (EJ) expression and was reversed by TLR2 stimulation in CD14-/- mice. Bone marrow (BM) transplantation revealed contribution of hematopoietic and non-hematopoietic cells towards intestinal homeostasis. EcN inoculated WT mice showed B cell activation, CD14-/- and TLR4-/- mice cytotoxic T cell and impaired B cell responses. The latter was characterized by absence of B cells in TLR4-/- mice, decreased levels of EcN induced immunoglobulins and downregulation of their transporter pIgR. EcN colonization of mice with genetically or antibody induced impaired B cell response resulted in dissemination of EcN and downregulation of EJ. BM chimeras indicated that CD14 originating from radiation resistant cells is sufficient to restore EJ-function. Overall, CD14/TLR4 signalling seems to be critical for intestinal barrier function and for the crosstalk between B cells and the epithelium, underlining that CD14 serves as a protective modulator of intestinal homeostasis.
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Affiliation(s)
- Marijana Basic
- Institute for Laboratory Animal Science, Hannover Medical School, 30625, Hannover, Germany
| | - Manuela Buettner
- Institute for Laboratory Animal Science, Hannover Medical School, 30625, Hannover, Germany
| | - Lydia M Keubler
- Institute for Laboratory Animal Science, Hannover Medical School, 30625, Hannover, Germany
| | - Anna Smoczek
- Institute for Laboratory Animal Science, Hannover Medical School, 30625, Hannover, Germany
| | - Inga Bruesch
- Institute for Laboratory Animal Science, Hannover Medical School, 30625, Hannover, Germany
| | - Stephanie Buchheister
- Institute for Laboratory Animal Science, Hannover Medical School, 30625, Hannover, Germany
| | - André Bleich
- Institute for Laboratory Animal Science, Hannover Medical School, 30625, Hannover, Germany.
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21
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PRR Function of Innate Immune Receptors in Recognition of Bacteria or Bacterial Ligands. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1112:255-280. [DOI: 10.1007/978-981-13-3065-0_18] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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22
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Lipopolysaccharide (LPS)-mediated priming of toll-like receptor 4 enhances oxidant-induced prostaglandin E 2 biosynthesis in primary murine macrophages. Int Immunopharmacol 2017; 54:226-237. [PMID: 29161659 DOI: 10.1016/j.intimp.2017.11.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 12/17/2022]
Abstract
Agonists and pseudo-agonists for toll-like receptor 4 (TLR4) are common in our environment. Thus, human exposure to these agents may result in "priming or sensitization" of TLR4. A body of evidence suggests that LPS-mediated sensitization of TLR4 can increase the magnitude of responses to exogenous agents in multiple tissues. We have previously shown that reactive oxygen and nitrogen species (RONS) stimulate TLR4. There is no evidence that LPS-primed TLR4 can influence the magnitude of responses to oxidants from either endogenous or exogenous sources. In the present study, we directly tested the hypothesis that LPS-primed TLR4 will sensitize primary murine peritoneal macrophages (pM) to oxidant-mediated prostaglandin E2 (PGE2) production. We used potassium peroxychromate (PPC) and potassium peroxynitrite (PPN) as direct in vitro sources of exogenous RONS. Our results showed that a direct treatment with PPC or PPN alone as sources of exogenous oxidants had a limited effect on PGE2 biosynthesis. In contrast, pM sensitized by prior incubation with LPS-EK, a TLR4-specific agonist, followed by oxidant stimulation exhibited increased transcriptional and translational expression of cyclooxygenase-2 (COX-2) with enhanced PGE2 biosynthesis/production only in pM derived from TLR4-WT mice but not in TLR4-KO mice. Thus, we have shown a critical role for LPS-primed TLR4 in oxidant-induced inflammatory phenotypes that have the potential to initiate, propagate and maintain many human diseases.
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23
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Li D, Wang P, Wang P, Hu X, Chen F. Targeting the gut microbiota by dietary nutrients: A new avenue for human health. Crit Rev Food Sci Nutr 2017; 59:181-195. [DOI: 10.1080/10408398.2017.1363708] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Daotong Li
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture; Engineering Research Centre for Fruits and Vegetables Processing, Ministry of Education, China Agricultural University, Beijing, China
| | - Pan Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture; Engineering Research Centre for Fruits and Vegetables Processing, Ministry of Education, China Agricultural University, Beijing, China
| | - Pengpu Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture; Engineering Research Centre for Fruits and Vegetables Processing, Ministry of Education, China Agricultural University, Beijing, China
| | - Xiaosong Hu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture; Engineering Research Centre for Fruits and Vegetables Processing, Ministry of Education, China Agricultural University, Beijing, China
| | - Fang Chen
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture; Engineering Research Centre for Fruits and Vegetables Processing, Ministry of Education, China Agricultural University, Beijing, China
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24
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Bernier-Latmani J, Petrova TV. Intestinal lymphatic vasculature: structure, mechanisms and functions. Nat Rev Gastroenterol Hepatol 2017; 14:510-526. [PMID: 28655884 DOI: 10.1038/nrgastro.2017.79] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mammalian intestine is richly supplied with lymphatic vasculature, which has functions ranging from maintenance of interstitial fluid balance to transport of antigens, antigen-presenting cells, dietary lipids and fat-soluble vitamins. In this Review, we provide in-depth information concerning the organization and structure of intestinal lymphatics, the current view of their developmental origins, as well as molecular mechanisms of intestinal lymphatic patterning and maintenance. We will also discuss physiological aspects of intestinal lymph flow regulation and the known and emerging roles of intestinal lymphatic vessels in human diseases, such as IBD, infection and cancer.
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Affiliation(s)
- Jeremiah Bernier-Latmani
- Department of Fundamental Oncology, Ludwig Institute for Cancer Research and Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne (UNIL), Chemin des Boveresses 155, Epalinges, Switzerland
| | - Tatiana V Petrova
- Department of Fundamental Oncology, Ludwig Institute for Cancer Research and Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne (UNIL), Chemin des Boveresses 155, Epalinges, Switzerland.,Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology Lausanne, Route Cantonale 1015, Lausanne, Switzerland
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25
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Buchheister S, Buettner M, Basic M, Noack A, Breves G, Buchen B, Keubler LM, Becker C, Bleich A. CD14 Plays a Protective Role in Experimental Inflammatory Bowel Disease by Enhancing Intestinal Barrier Function. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:1106-1120. [DOI: 10.1016/j.ajpath.2017.01.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 01/04/2017] [Accepted: 01/30/2017] [Indexed: 12/24/2022]
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26
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He L, Li H, Huang N, Zhou X, Tian J, Li T, Wu J, Tian Y, Yin Y, Yao K. Alpha-ketoglutarate suppresses the NF-κB-mediated inflammatory pathway and enhances the PXR-regulated detoxification pathway. Oncotarget 2017; 8:102974-102988. [PMID: 29262538 PMCID: PMC5732704 DOI: 10.18632/oncotarget.16875] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Accepted: 03/17/2017] [Indexed: 01/18/2023] Open
Abstract
Alpha-ketoglutarate (AKG) is a critical nutritional factor in the maintenance of intestinal homeostasis. However, the relative mechanism of AKG has not been well understood. It was recently shown that the interaction between nuclear factor kappa B (NF-κB)-mediated inflammatory pathway and pregnane X receptor (PXR)-regulated detoxification pathway is a check and balance mechanism for keeping the homeostatic state of the intestine, preventing the onset of intestinal inflammation which may lead to cancer. In the current study we used lipopolysaccharide (LPS)-challenged piglet and intestinal porcine epithelial cells-J2 models to investigate the effects of dietary AKG supplementation on the intestinal immune system and PXR regulated target expression. We found that LPS induced significant activation of the NF-κB-mediated inflammatory pathway with concomitant impairment of intestinal nutrient absorption. AKG administration increased intracellular AKG and its metabolite concentrations and enhanced the mRNA expression of alpha-ketoglutarate dehydrogenase in vivo and in vitro. Thus dietary AKG supplementation reversed the adverse effects induced by LPS. We also found a strong inhibitory effects on the NF-κB-mediated inflammatory pathway, especially, in the AKG-treated intestinal tissues, LPS-induced NF-κB phosphorylation was inhibited and TNF-α was suppressed. Interestingly, AKG has potent effects in regulating the PXR and its downstream targets such as CYP3As and CYP2Bs in vivo and in vitro, although AKG is not a known PXR ligand. One potential mechanism for the up-regulation of the PXR pathway is through the down-regulation of NF-κB pathway which in turn de-represses the PXR-regulated target expression. Taken together, our results suggest that AKG improves intestinal immune system through modulating the interaction between PXR and NF-κB. Our findings have important implications for the prevention and treatment of intestinal inflammatory diseases in neonates.
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Affiliation(s)
- Liuqin He
- Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan 410125, China.,University of Chinese Academy of Sciences, Huairou, Beijing 10008, China
| | - Huan Li
- College of Animal Science and Technology, Hunan Agricultural University, Hunan, Changsha 410128, China
| | - Niu Huang
- College of Animal Science and Technology, Hunan Agricultural University, Hunan, Changsha 410128, China
| | - Xihong Zhou
- Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan 410125, China
| | - Junquan Tian
- Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan 410125, China.,University of Chinese Academy of Sciences, Huairou, Beijing 10008, China
| | - Tiejun Li
- Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan 410125, China.,Hunan Co-Innovation Center of Animal Production Safety, Hunan, Changsha 410128, China
| | - Jing Wu
- College of Animal Science and Technology, Hunan Agricultural University, Hunan, Changsha 410128, China
| | - Yanan Tian
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Yulong Yin
- Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan 410125, China.,Hunan Co-Innovation Center of Animal Production Safety, Hunan, Changsha 410128, China
| | - Kang Yao
- Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan 410125, China.,Hunan Co-Innovation Center of Animal Production Safety, Hunan, Changsha 410128, China
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27
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Larsson O, Tengroth L, Xu Y, Uddman R, Kumlien Georén S, Cardell LO. Substance P represents a novel first-line defense mechanism in the nose. J Allergy Clin Immunol 2017; 141:128-136.e3. [PMID: 28219705 DOI: 10.1016/j.jaci.2017.01.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 11/14/2016] [Accepted: 01/23/2017] [Indexed: 02/03/2023]
Abstract
BACKGROUND Neuropeptides, such as substance P (SP), have long been seen as mediators of widespread continuous airway inflammation, a process known as neurogenic inflammation. However, this has been difficult to demonstrate clinically, suggesting an alternative role for these signaling molecules. OBJECTIVES We sought to examine the role of SP in nasal infection by assessing the release of SP in response to viral stimulation and characterizing the effects of SP on innate immunity, with the latter reflected in changes in local Toll-like receptor (TLR) expression. METHODS The distribution of SP and TLRs in the nasal mucosa and local airway neurons was assessed with immunohistochemistry. The TLR7 agonists R-837 and R-848 were used to mimic a viral insult in the upper airways represented by primary human nasal epithelial cells (HNECs) and murine nasal epithelial cells (MNECs) and isolated murine trigeminal ganglial neurons. SP release from HNECs, MNECs, and trigeminal ganglial neurons was quantified with EIA. The effects of SP on TLR expression on HNECs were determined by using flow cytometry and confocal microscopy. RESULTS SP was released from the sensory neurons, MNECs, and HNECs within 15 minutes of local TLR7 stimulation. Subsequently, stimulation with SP induced upregulation of TLR expression in HNECs within 30 minutes through induction of TLR movement within HNECs. Upregulation of TLR expression was not evident when cells were treated with the neurokinin 1 receptor antagonist aprepitant before SP stimulation. CONCLUSIONS This highlights a novel role for sensory neuropeptides as acute and local mediators of pathogen-driven inflammation, rapidly priming innate immune defenses in the airway.
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Affiliation(s)
- Olivia Larsson
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden
| | - Lotta Tengroth
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden
| | - Yuan Xu
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden
| | - Rolf Uddman
- Department of Otorhinolaryngology, Lund University, Skåne University Hospital, Malmö, Sweden
| | | | - Lars-Olaf Cardell
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden; Department of ENT Diseases, Karolinska University Hospital, Stockholm, Sweden.
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28
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Monocyte-lymphocyte fusion induced by the HIV-1 envelope generates functional heterokaryons with an activated monocyte-like phenotype. Exp Cell Res 2017; 352:9-19. [PMID: 28132881 DOI: 10.1016/j.yexcr.2017.01.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 01/23/2017] [Accepted: 01/25/2017] [Indexed: 02/08/2023]
Abstract
Enveloped viruses induce cell-cell fusion when infected cells expressing viral envelope proteins interact with target cells, or through the contact of cell-free viral particles with adjoining target cells. CD4+ T lymphocytes and cells from the monocyte-macrophage lineage express receptors for HIV envelope protein. We have previously reported that lymphoid Jurkat T cells expressing the HIV-1 envelope protein (Env) can fuse with THP-1 monocytic cells, forming heterokaryons with a predominantly myeloid phenotype. This study shows that the expression of monocytic markers in heterokaryons is stable, whereas the expression of lymphoid markers is mostly lost. Like THP-1 cells, heterokaryons exhibited FcγR-dependent phagocytic activity and showed an enhanced expression of the activation marker ICAM-1 upon stimulation with PMA. In addition, heterokaryons showed morphological changes compatible with maturation, and high expression of the differentiation marker CD11b in the absence of differentiation-inducing agents. No morphological change nor increase in CD11b expression were observed when an HIV-fusion inhibitor blocked fusion, or when THP-1 cells were cocultured with Jurkat cells expressing a non-fusogenic Env protein, showing that differentiation was not induced merely by cell-cell interaction but required cell-cell fusion. Inhibition of TLR2/TLR4 signaling by a TIRAP inhibitor greatly reduced the expression of CD11b in heterokaryons. Thus, lymphocyte-monocyte heterokaryons induced by HIV-1 Env are stable and functional, and fusion prompts a phenotype characteristic of activated monocytes via intracellular TLR2/TLR4 signaling.
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29
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Hornef MW, Bogdan C. The role of epithelial Toll-like receptor expression in host defense and microbial tolerance. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519050110020901] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The recognition of microbial structures by Toll-like receptors (TLRs) on professional immune cells situated at sterile internal body sites occurs during invasive microbial infection. It indicates infectious non-self and thereby represents the adequate co-stimulatory signal to initiate activation of the adaptive immune system against the invading pathogen. In contrast, most epithelial body surfaces are permanently colonized by microbial organisms of the normal flora and thus TLR ligands are present under physiological conditions. In the following, we discuss the characteristics of TLR-mediated recognition by epithelial cells, the subsequent activation of the host immune system, and protective mechanisms that might help to avoid inadequate stimulation and allow differentiation between commensal or pathogenic micro-organisms. Recent findings suggest that the role of epithelial cells in the maintenance of stable microbial colonization of host surfaces and the immediate host response to infectious challenges might have to be revised.
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Affiliation(s)
- Mathias W. Hornef
- Institute for Medical Microbiology and Hygiene, University of Freiburg, Germany, Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden,
| | - Christian Bogdan
- Institute for Medical Microbiology and Hygiene, University of Freiburg, Germany
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30
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Guerville M, Boudry G. Gastrointestinal and hepatic mechanisms limiting entry and dissemination of lipopolysaccharide into the systemic circulation. Am J Physiol Gastrointest Liver Physiol 2016; 311:G1-G15. [PMID: 27151941 DOI: 10.1152/ajpgi.00098.2016] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/30/2016] [Indexed: 01/31/2023]
Abstract
The human microbiota consists of 100 trillion microorganisms that provide important metabolic and biological functions benefiting the host. However, the presence in host plasma of a gut-derived bacteria component, the lipopolysaccharide (LPS), has been identified as a causal or complicating factor in multiple serious diseases such as sepsis and septic shock and, more recently, obesity-associated metabolic disorders. Understanding the precise mechanisms by which gut-derived LPS is transported from the gut lumen to the systemic circulation is crucial to advance our knowledge of LPS-associated diseases and elaborate targeted strategies for their prevention. The aim of this review is to synthetize current knowledge on the host mechanisms limiting the entry and dissemination of LPS into the systemic circulation. To prevent bacterial colonization and penetration, the intestinal epithelium harbors multiple defense mechanisms including the secretion of antimicrobial peptides and mucins as well as detoxification enzymes. Despite this first line of defense, LPS can reach the apical site of intestinal epithelial cells (IECs) and, because of its large size, likely crosses IECs via transcellular transport, either lipid raft- or clathrin-mediated endocytosis or goblet cell-associated passage. However, the precise pathway remains poorly described. Finally, if LPS crosses the gut mucosa, it is directed via the portal vein to the liver, where major detoxification processes occur by deacetylation and excretion through the bile. If this disposal process is not sufficient, LPS enters the systemic circulation, where it is handled by numerous transport proteins that clear it back to the liver for further excretion.
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Affiliation(s)
| | - Gaëlle Boudry
- INRA UR1341 ADNC, Domaine de la Prise, Saint-Gilles, France
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31
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Hersoug LG, Møller P, Loft S. Gut microbiota-derived lipopolysaccharide uptake and trafficking to adipose tissue: implications for inflammation and obesity. Obes Rev 2016; 17:297-312. [PMID: 26712364 DOI: 10.1111/obr.12370] [Citation(s) in RCA: 174] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 12/12/2022]
Abstract
The composition of the gut microbiota and excessive ingestion of high-fat diets (HFD) are considered to be important factors for development of obesity. In this review we describe a coherent mechanism of action for the development of obesity, which involves the composition of gut microbiota, HFD, low-grade inflammation, expression of fat translocase and scavenger receptor CD36, and the scavenger receptor class B type 1 (SR-BI). SR-BI binds to both lipids and lipopolysaccharide (LPS) from Gram-negative bacteria, which may promote incorporation of LPS in chylomicrons (CMs). These CMs are transported via lymph to the circulation, where LPS is transferred to other lipoproteins by translocases, preferentially to HDL. LPS increases the SR-BI binding, transcytosis of lipoproteins over the endothelial barrier,and endocytosis in adipocytes. Especially large size adipocytes with high metabolic activity absorb LPS-rich lipoproteins. In addition, macrophages in adipose tissue internalize LPS-lipoproteins. This may contribute to the polarization from M2 to M1 phenotype, which is a consequence of increased LPS delivery into the tissue during hypertrophy. In conclusion, evidence suggests that LPS is involved in the development of obesity as a direct targeting molecule for lipid delivery and storage in adipose tissue.
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Affiliation(s)
- L-G Hersoug
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - P Møller
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - S Loft
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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32
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Utzschneider KM, Kratz M, Damman CJ, Hullar M. Mechanisms Linking the Gut Microbiome and Glucose Metabolism. J Clin Endocrinol Metab 2016; 101:1445-54. [PMID: 26938201 PMCID: PMC4880177 DOI: 10.1210/jc.2015-4251] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This review details potential mechanisms linking gut dysbiosis to metabolic dysfunction, including lipopolysaccharide, bile acids, short chain fatty acids, gut hormones, and branched-chain amino acids.
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Affiliation(s)
- Kristina M Utzschneider
- Division of Metabolism, Endocrinology and Nutrition (K.M.U.), Department of Medicine, VA Puget Sound Health Care System and the University of Washington, Seattle, Washington; Division of Public Health Sciences (M.K.), Fred Hutchinson Cancer Research Center, and the Department of Epidemiology, University of Washington, Seattle, Washington; Division of Gastroenterology (C.J.D.), Department of Medicine, University of Washington, Seattle, Washington; and Division of Public Health Sciences (M.H.), Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Mario Kratz
- Division of Metabolism, Endocrinology and Nutrition (K.M.U.), Department of Medicine, VA Puget Sound Health Care System and the University of Washington, Seattle, Washington; Division of Public Health Sciences (M.K.), Fred Hutchinson Cancer Research Center, and the Department of Epidemiology, University of Washington, Seattle, Washington; Division of Gastroenterology (C.J.D.), Department of Medicine, University of Washington, Seattle, Washington; and Division of Public Health Sciences (M.H.), Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Chris J Damman
- Division of Metabolism, Endocrinology and Nutrition (K.M.U.), Department of Medicine, VA Puget Sound Health Care System and the University of Washington, Seattle, Washington; Division of Public Health Sciences (M.K.), Fred Hutchinson Cancer Research Center, and the Department of Epidemiology, University of Washington, Seattle, Washington; Division of Gastroenterology (C.J.D.), Department of Medicine, University of Washington, Seattle, Washington; and Division of Public Health Sciences (M.H.), Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Meredith Hullar
- Division of Metabolism, Endocrinology and Nutrition (K.M.U.), Department of Medicine, VA Puget Sound Health Care System and the University of Washington, Seattle, Washington; Division of Public Health Sciences (M.K.), Fred Hutchinson Cancer Research Center, and the Department of Epidemiology, University of Washington, Seattle, Washington; Division of Gastroenterology (C.J.D.), Department of Medicine, University of Washington, Seattle, Washington; and Division of Public Health Sciences (M.H.), Fred Hutchinson Cancer Research Center, Seattle, Washington
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33
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Orivuori L, Mustonen K, de Goffau MC, Hakala S, Paasela M, Roduit C, Dalphin JC, Genuneit J, Lauener R, Riedler J, Weber J, von Mutius E, Pekkanen J, Harmsen HJM, Vaarala O. High level of fecal calprotectin at age 2 months as a marker of intestinal inflammation predicts atopic dermatitis and asthma by age 6. Clin Exp Allergy 2016; 45:928-939. [PMID: 25758537 DOI: 10.1111/cea.12522] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 01/05/2015] [Accepted: 01/16/2015] [Indexed: 01/27/2023]
Abstract
BACKGROUND Gut microbiota and intestinal inflammation regulate the development of immune-mediated diseases, such as allergies. Fecal calprotectin is a biomarker of intestinal inflammation. OBJECTIVE We evaluated the association of early-age fecal calprotectin levels to the later development of allergic diseases in children from farming and non-farming environments and further studied the effect of gut microbiota on the fecal calprotectin levels. METHODS Fecal calprotectin was measured from 758 infants participating in the PASTURE study at the age of 2 months using the ELISA method. Serum-specific IgE levels were measured at 6 years of age. Data of environmental factors, doctor-diagnosed atopic dermatitis (AD) and asthma were collected by questionnaire. Multivariate logistic regression models were used for analysis. The composition of fecal microbiota was analysed in a subgroup of 120 infants with 16S rRNA pyrosequencing. The effect of Escherichia coli lipopolysaccharide (LPS) on in vitro monocyte IL-10 secretion was studied by flow cytometry. RESULTS The infants with high fecal calprotectin levels at 2 months, that is above the 90th percentile, had an increased risk of developing AD and asthma/asthmatic bronchitis by the age of 6 years (aOR 2.02 (1.06-3.85) and 2.41 (1.25-4.64), respectively). High fecal calprotectin levels correlated negatively with fecal Escherichia. LPS from E. coli stimulated production of IL-10 in monocytes. CONCLUSION AND CLINICAL RELEVANCE High degree intestinal inflammation at 2 months of age, detected as high fecal calprotectin, predicted asthma and AD by the age of 6 years and was linked to low abundance of fecal Escherichia. Impaired IL-10 activation due to the lack of colonization with E. coli could explain the intestinal inflammation associated high fecal calprotectin and later risk of asthma and AD. Our results have implications for the design of probiotic treatments and suggest that early intestinal colonization has long-term health effects.
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Affiliation(s)
- L Orivuori
- Institute of Clinical Medicine, University of Helsinki, Helsinki, Finland.,Department of Vaccination and Immune Protection, National Institute for Health and Welfare, Helsinki, Finland
| | - K Mustonen
- Environmental Health Department, National Institute for Health and Welfare, Kuopio, Finland
| | - M C de Goffau
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - S Hakala
- Department of Vaccination and Immune Protection, National Institute for Health and Welfare, Helsinki, Finland
| | - M Paasela
- Department of Vaccination and Immune Protection, National Institute for Health and Welfare, Helsinki, Finland
| | - C Roduit
- Christine Kühne - Center for Allergy Research and Education (CK-CARE), Davos, Switzerland.,Children's Hospital, University of Zurich, Zurich, Switzerland
| | - J-C Dalphin
- The Department of Respiratory Disease, Université de Franche-Comté, UMR-CNRS Chrono-Environnement, University Hospital, Besançon, France
| | - J Genuneit
- Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany
| | - R Lauener
- Christine Kühne - Center for Allergy Research and Education (CK-CARE), Davos, Switzerland.,Children's Hospital of Eastern Switzerland, St. Gallen, Switzerland
| | - J Riedler
- Children and Young Adults' Medicine, Children's Hospital, Schwarzach, Austria
| | - J Weber
- Dr. von Hauner Children's Hospital of the Ludwig Maximilian University Munich, Munich, Germany
| | - E von Mutius
- Dr. von Hauner Children's Hospital of the Ludwig Maximilian University Munich, Munich, Germany.,Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research, Mölndal, Sweden
| | - J Pekkanen
- Environmental Health Department, National Institute for Health and Welfare, Kuopio, Finland
| | - H J M Harmsen
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - O Vaarala
- Institute of Clinical Medicine, University of Helsinki, Helsinki, Finland.,Respiratory, Inflammation and Autoimmunity, Innovative Medicine, AstraZeneca R & D, Mölndal, Sweden
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34
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Crisafulli C, Drago A, Calabrò M, Spina E, Serretti A. A molecular pathway analysis informs the genetic background at risk for schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2015; 59:21-30. [PMID: 25554435 DOI: 10.1016/j.pnpbp.2014.12.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/22/2014] [Accepted: 12/23/2014] [Indexed: 01/01/2023]
Abstract
BACKGROUND Schizophrenia is a complex mental disorder marked by severely impaired thinking, delusional thoughts, hallucinations and poor emotional responsiveness. The biological mechanisms that lead to schizophrenia may be related to the genetic background of patients. Thus, a genetic perspective may help to unravel the molecular pathways disrupted in schizophrenia. METHODS In the present work, we used a molecular pathway analysis to identify the molecular pathways associated with schizophrenia. We collected data of genetic loci previously associated with schizophrenia, identified the genes located in those positions and created the metabolic pathways that are related to those genes' products. These pathways were tested for enrichment (a number of SNPs associated with the phenotype significantly higher than expected by chance) in a sample of schizophrenic patients and controls (4486 and 4477, respectively). RESULTS The molecular pathway that resulted from the identification of all the genes located in the loci previously found to be associated with schizophrenia was found to be enriched, as expected (permutated p(10(6))=9.9999e-06).We found 60 SNPs amongst 30 different genes with a strong association with schizophrenia. The genes are related to the pathways related to neurodevelopment, apoptosis, vesicle traffic, immune response and MAPK cascade. CONCLUSIONS The pathway related to the toll-like receptor family seemed to play a central role in the modulation/connection of various pathways whose disruption leads to schizophrenia. This pathway is related to the innate immune system, further stressing the role of immunological-related events in increasing the risk to schizophrenia.
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Affiliation(s)
- Concetta Crisafulli
- Department of Biomedical Science and Morphological and Functional Images, University of Messina, Messina, Italy
| | - Antonio Drago
- Department of Biomedical and Neuromotor Sciences - DIBINEM, University of Bologna, Bologna, Italy; I.R.C.C.S. "San Giovanni di Dio", Fatebenefratelli, Brescia, Italy.
| | - Marco Calabrò
- Department of Biomedical Science and Morphological and Functional Images, University of Messina, Messina, Italy; Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy; IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy
| | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Alessandro Serretti
- Department of Biomedical and Neuromotor Sciences - DIBINEM, University of Bologna, Bologna, Italy
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35
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Yu S, Gao N. Compartmentalizing intestinal epithelial cell toll-like receptors for immune surveillance. Cell Mol Life Sci 2015; 72:3343-53. [PMID: 26001904 DOI: 10.1007/s00018-015-1931-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/13/2015] [Accepted: 05/18/2015] [Indexed: 02/08/2023]
Abstract
Toll-like receptors (TLRs) are membrane-bound microbial sensors that mediate important host-to-microbe responses. Cell biology aspects of TLR function have been intensively studied in professional immune cells, in particular the macrophages and dendritic cells, but not well explored in other specialized epithelial cell types. The adult intestinal epithelial cells are in close contact with trillions of enteric microbes and engage in lifelong immune surveillance. Mature intestinal epithelial cells, in contrast to immune cells, are highly polarized. Recent studies suggest that distinct mechanisms may govern TLR traffic and compartmentalization in these specialized epithelial cells to establish and maintain precise signaling of individual TLRs. We, using immune cells as references, discuss here the shared and/or unique molecular machineries used by intestinal epithelial cells to control TLR transport, localization, processing, activation, and signaling. A better understanding of these mechanisms will certainly generate important insights into both the mechanism and potential intervention of leading digestive disorders, in particular inflammatory bowel diseases.
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Affiliation(s)
- Shiyan Yu
- Department of Biological Sciences, Rutgers University, Room 206, 195 University Ave., Newark, NJ, 07102, USA
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36
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Duperray A, Barbe D, Raguenez G, Weksler BB, Romero IA, Couraud PO, Perron H, Marche PN. Inflammatory response of endothelial cells to a human endogenous retrovirus associated with multiple sclerosis is mediated by TLR4. Int Immunol 2015; 27:545-53. [PMID: 25957268 PMCID: PMC4625887 DOI: 10.1093/intimm/dxv025] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 05/01/2015] [Indexed: 02/06/2023] Open
Abstract
The MSRV (multiple sclerosis-associated retrovirus) belongs to the human endogenous retrovirus HERV-W family. The envelope protein originating from the MSRV has been found in most patients with multiple sclerosis (MS). This protein (Env-ms) has pro-inflammatory properties for several types of immune cells and could therefore play a role in MS pathogenesis by promoting the leukocyte diapedesis observed in the central nervous system of patients. Our study aims to analyze the effects of Env-ms on the blood-brain barrier (BBB) at a molecular and functional level. We demonstrate that the recombinant MSRV envelope is able to stimulate several inflammatory parameters in a human BBB in vitro model, the HCMEC/D3 brain endothelial cell line. Indeed, Env-ms induces over-expression of ICAM-1, a major mediator of leukocyte adhesion to endothelial cells, in a dose-dependent manner as well as a strong dose-dependent production of the pro-inflammatory cytokines IL-6 and IL-8. Furthermore, using a silencing approach with siRNAs, we show that Env-ms is recognized via the Toll-like receptor 4 receptor, a pattern recognition receptor of innate immunity present on endothelial cells. We also show, using functional assays, that treatment of brain endothelial cells with Env-ms significantly stimulated the adhesion and the transmigration of activated immune cells through a monolayer of endothelial cells. These findings support the hypothesis that MSRV could be involved in the pathogenesis of MS disease or at least in maintenance of inflammatory conditions, thus fueling the auto-immune disorder. MSRV could also play a role in other chronic inflammatory diseases.
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Affiliation(s)
- Alain Duperray
- INSERM U823, F-38000 Grenoble, France Université Grenoble Alpes, IAB, F-38000 Grenoble, France
| | - Delphin Barbe
- INSERM U823, F-38000 Grenoble, France Université Grenoble Alpes, IAB, F-38000 Grenoble, France
| | - Gilda Raguenez
- INSERM U823, F-38000 Grenoble, France Université Grenoble Alpes, IAB, F-38000 Grenoble, France Present address: Centre de Recherche en Neurobiologie - Neurophysiologie de Marseille, Université de la Méditerranée Aix-Marseille 2, CNRS UMR7286, 13344 Marseille, France
| | - Babette B Weksler
- Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Ignacio A Romero
- Department of Biological Sciences, The Open University, Walton Hall, Milton Keynes MK7 6BJ, UK
| | | | - Hervé Perron
- GeNeuro, 18, chemin des Aulx, 1228 Plan-les-Ouates, Geneva, Switzerland
| | - Patrice N Marche
- INSERM U823, F-38000 Grenoble, France Université Grenoble Alpes, IAB, F-38000 Grenoble, France
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Interplay of the Gastric Pathogen Helicobacter pylori with Toll-Like Receptors. BIOMED RESEARCH INTERNATIONAL 2015; 2015:192420. [PMID: 25945326 PMCID: PMC4402485 DOI: 10.1155/2015/192420] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 12/29/2014] [Indexed: 12/18/2022]
Abstract
Toll-like receptors (TLRs) are crucial for pathogen recognition and downstream signaling to induce effective immunity. The gastric pathogen Helicobacter pylori is a paradigm of persistent bacterial infections and chronic inflammation in humans. The chronicity of inflammation during H. pylori infection is related to the manipulation of regulatory cytokines. In general, the early detection of H. pylori by TLRs and other pattern recognition receptors (PRRs) is believed to induce a regulatory cytokine or chemokine profile that eventually blocks the resolution of inflammation. H. pylori factors such as LPS, HSP-60, NapA, DNA, and RNA are reported in various studies to be recognized by specific TLRs. However, H. pylori flagellin evades the recognition of TLR5 by possessing a conserved N-terminal motif. Activation of TLRs and resulting signal transduction events lead to the production of pro- and anti-inflammatory mediators through activation of NF-κB, MAP kinases, and IRF signaling pathways. The genetic polymorphisms of these important PRRs are also implicated in the varied outcome and disease progression. Hence, the interplay of TLRs and bacterial factors highlight the complexity of innate immune recognition and immune evasion as well as regulated processes in the progression of associated pathologies. Here we will review this important aspect of H. pylori infection.
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Abstract
BACKGROUND Toll-like receptor (TLR) expression in patients with inflammatory bowel disease is increased when compared with healthy controls. However, the impact of TLR signaling during inflammatory bowel disease is not fully understood. METHODS In this study, we used a murine model of acute phase inflammation in bone marrow chimeric mice to investigate in which cell type TLR2/4 signal induction is important in preventing intestinal inflammation and how intestinal dendritic cells are influenced. Mice were either fed with wild-type bacteria, able to initiate the TLR2/4 signaling cascade, or with mutant strains with impaired signal induction capacity. RESULTS The induction of the TLR2/4 signal cascade in epithelial cells resulted in inflammation in bone marrow chimeric mice, whereas induction in hematopoietic cells had an opposed function. Furthermore, feeding of wild-type bacteria prevented disease; however, differing signal induction of bacteria had no effect on lamina propria dendritic cell activation. In contrast, functional TLR2/4 signals resulted in increased frequencies of CD103-expressing lamina propria and mesenteric lymph node dendritic cells, which were able to ameliorate disease. CONCLUSIONS The TLR-mediated amelioration of disease, the increase in CD103-expressing cells, and the beneficial function of TLR signal induction in hematopoietic cells indicate that the increased expression of TLRs in patients with inflammatory bowel disease might result in counterregulation of the host and serve in preventing disease.
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Meng D, Zhu W, Shi HN, Lu L, Wijendran V, Xu W, Walker WA. Toll-like receptor-4 in human and mouse colonic epithelium is developmentally regulated: a possible role in necrotizing enterocolitis. Pediatr Res 2015; 77:416-24. [PMID: 25521917 PMCID: PMC4479150 DOI: 10.1038/pr.2014.207] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 10/03/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND Necrotizing enterocolitis (NEC) is an immature intestinal condition resulting in devastating intestinal inflammation due to unknown mechanisms. Evidence has suggested that intestinal maturation attenuates the severity of NEC and Toll-like receptor 4 (TLR4) has been suggested to play a critical role in its pathogenesis. We investigated whether maturational effects of TLR4 expression in immature colon might contribute to the development of NEC. METHODS TLR4 colonocyte expression was detected by immunofluorescence confocal microscopy. Interleukin-6 (IL-6) levels were assayed by an enzyme-linked immunosorbent assay (ELISA). RESULTS TLR4 expression was high in fetal colonic epithelium in human and mouse, with earlier gestation having a higher surface/cytoplasm distribution. TLR4 remained high in mouse postnatal day 1 but the surface/cytoplasm distribution was reduced. TLR4 decreased in amount and then was expressed in crypts in the mature human and mouse colon. Hydrocortisone (HC) reduced the surface/cytoplasm distribution of TLR4 in human fetal colon. Elevated IL-6 levels in immature colon after lipopolysaccharide were attenuated by HC in human and mouse. CONCLUSION Expression, localization, and signaling of TLR4 in colonic epithelium may be developmentally regulated. HC may accelerate the TLR developmental pathway change to an adult type, which may account for its impact on TLR4 signaling.
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Affiliation(s)
- Di Meng
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, USA
| | - Weishu Zhu
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, USA
| | - Hai Ning Shi
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, USA
| | - Lei Lu
- Section of Neonatology, Department of Pediatrics and Medicine, The University of Chicago, Chicago, IL, USA
| | - Vasuki Wijendran
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, USA
| | - Winber Xu
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, USA
| | - W. Allan Walker
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, USA
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Characterization of Toll-like receptor-4 (TLR-4) in the spleen and thymus of Swiss albino mice and its modulation in experimental endotoxemia. J Immunol Res 2015; 2015:137981. [PMID: 25759837 PMCID: PMC4352500 DOI: 10.1155/2015/137981] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 01/19/2015] [Accepted: 01/19/2015] [Indexed: 01/11/2023] Open
Abstract
Expression of innate immune receptors varies among organs and species and within different strains among the same species; thus, periodic classification of different pattern recognition receptors in the available strains is necessary to initiate different therapeutic approaches to combat inflammation. On characterization of TLR-4 in spleen and thymus of Swiss albino mice—with no reports of TLR-4 expression—induced with endotoxemia, it was found that the mode of expression varied among the organs at both mRNA and protein level in a time-dependent manner. Their functionality was verified by measuring proinflammatory and anti-inflammatory cytokines. In the in vitro study using isolated macrophages and lymphocytes from the same organs, the expression of TLR-4 after a shorter period of LPS stimulation was verified. The results substantiated the potent role of macrophage on LPS challenge compared to lymphocytes. The diverse pattern of TLR-4 expression on different cell population indicated their distinct functional activity in LPS-endotoxemia. It may be hypothesized that the expression patterns of TLR-4 could be different based on the anatomical localization and the varying bacterial milieu or bacterial endotoxin encountered in each anatomical location. Thus, blocking TLR-4 or administering IL-6 or IL-10 might impart protection against endotoxemia in the clinical field.
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Brown M, Hughes KR, Moossavi S, Robins A, Mahida YR. Toll-like receptor expression in crypt epithelial cells, putative stem cells and intestinal myofibroblasts isolated from controls and patients with inflammatory bowel disease. Clin Exp Immunol 2014; 178:28-39. [PMID: 24828022 PMCID: PMC4231243 DOI: 10.1111/cei.12381] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2014] [Indexed: 12/19/2022] Open
Abstract
The aim of our studies was to investigate the expression of Toll-like receptor (TLR)-2 and TLR-4 (and in some studies TLR-5) in myofibroblasts and small and large intestinal crypt epithelial cells from control patients and those affected by Crohn's disease and ulcerative colitis. Isolated and disaggregated crypt epithelial cells and monolayers of myofibroblasts were used for studies by reverse transcription–polymerase chain reaction (RT–PCR), real-time RT–PCR, flow cytometry, immunocytochemistry and Western blot analysis. Compared to control cells, crypt epithelial cells isolated from active ulcerative colitis and Crohn's disease colonic mucosal samples showed significantly higher expression of TLR-2 and TLR-4 transcripts and protein (on the cell surface). There was also enhanced expression of TLR-4 in crypt cells from ileal Crohn's disease. Expression of TLR-2 and TLR-4 transcripts in crypt epithelial cells isolated from inflamed mucosa of distal ulcerative colitis did not differ significantly from such cells obtained from the normal proximal colon. Crypt epithelial cells with side population characteristics (putative stem cells) also expressed transcripts and protein for TLR-2, TLR-4 and TLR-5. Colonic myofibroblast expression of these TLRs was much weaker than in crypt epithelial cells. In conclusion, enhanced TLR-2 and TLR-4 expression by crypt epithelial cells in active inflammatory bowel disease likely reflects greater ability to respond to microbial products. Results from our studies using mucosal samples from patients with distal ulcerative colitis suggest that the enhanced expression of these TLRs could be constitutive. TLR-2, TLR-4 and TLR-5 expression by stem cells imply ability to respond to distinct bacterial products.
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Affiliation(s)
- M Brown
- Institute of Infection, Immunity and Inflammation, University of Nottingham, UK; Nottingham Digestive Diseases Centre, University of Nottingham, UK
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Hörmann N, Brandão I, Jäckel S, Ens N, Lillich M, Walter U, Reinhardt C. Gut microbial colonization orchestrates TLR2 expression, signaling and epithelial proliferation in the small intestinal mucosa. PLoS One 2014; 9:e113080. [PMID: 25396415 PMCID: PMC4232598 DOI: 10.1371/journal.pone.0113080] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 10/19/2014] [Indexed: 01/19/2023] Open
Abstract
The gut microbiota is an environmental factor that determines renewal of the intestinal epithelium and remodeling of the intestinal mucosa. At present, it is not resolved if components of the gut microbiota can augment innate immune sensing in the intestinal epithelium via the up-regulation of Toll-like receptors (TLRs). Here, we report that colonization of germ-free (GF) Swiss Webster mice with a complex gut microbiota augments expression of TLR2. The microbiota-dependent up-regulation of components of the TLR2 signaling complex could be reversed by a 7 day broad-spectrum antibiotic treatment. TLR2 downstream signaling via the mitogen-activated protein kinase (ERK1/2) and protein-kinase B (AKT) induced by bacterial TLR2 agonists resulted in increased proliferation of the small intestinal epithelial cell line MODE-K. Mice that were colonized from birth with a normal gut microbiota (conventionally-raised; CONV-R) showed signs of increased small intestinal renewal and apoptosis compared with GF controls as indicated by elevated mRNA levels of the proliferation markers Ki67 and Cyclin D1, elevated transcripts of the apoptosis marker Caspase-3 and increased numbers of TUNEL-positive cells per intestinal villus structure. In accordance, TLR2-deficient mice showed reduced proliferation and reduced apoptosis. Our findings suggest that a tuned proliferation response of epithelial cells following microbial colonization could aid to protect the host from its microbial colonizers and increase intestinal surface area.
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Affiliation(s)
- Nives Hörmann
- Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Junior Group Translational Research in Thrombosis and Hemostasis, Mainz, Germany
| | - Inês Brandão
- Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Junior Group Translational Research in Thrombosis and Hemostasis, Mainz, Germany
| | - Sven Jäckel
- Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Junior Group Translational Research in Thrombosis and Hemostasis, Mainz, Germany
| | - Nelli Ens
- Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Junior Group Translational Research in Thrombosis and Hemostasis, Mainz, Germany
| | - Maren Lillich
- Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Junior Group Translational Research in Thrombosis and Hemostasis, Mainz, Germany
| | - Ulrich Walter
- Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Junior Group Translational Research in Thrombosis and Hemostasis, Mainz, Germany
| | - Christoph Reinhardt
- Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Junior Group Translational Research in Thrombosis and Hemostasis, Mainz, Germany
- * E-mail:
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43
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Günther C, Buchen B, Neurath MF, Becker C. Regulation and pathophysiological role of epithelial turnover in the gut. Semin Cell Dev Biol 2014; 35:40-50. [DOI: 10.1016/j.semcdb.2014.06.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 06/02/2014] [Indexed: 12/25/2022]
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McClure R, Massari P. TLR-Dependent Human Mucosal Epithelial Cell Responses to Microbial Pathogens. Front Immunol 2014; 5:386. [PMID: 25161655 PMCID: PMC4129373 DOI: 10.3389/fimmu.2014.00386] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 07/29/2014] [Indexed: 12/17/2022] Open
Abstract
Toll-like receptor (TLR) signaling represents one of the best studied pathways to implement defense mechanisms against invading microbes in human being as well as in animals. TLRs respond to specific microbial ligands and to danger signals produced by the host during infection, and initiate downstream cascades that activate both innate and adaptive immunity. TLRs are expressed by professional immune cells and by the large majority of non-hematopoietic cells, including epithelial cells. In epithelial tissues, TLR functions are particularly important because these sites are constantly exposed to microorganisms, due to their location at the host interface with the environment. While at these sites specific defense mechanisms and inflammatory responses are initiated via TLR signaling against pathogens, suppression or lack of TLR activation is also observed in response to the commensal microbiota. The mechanisms by which TLR signaling is regulated in mucosal epithelial cells include differential expression and levels of TLRs (and their signaling partners), their cellular localization and positioning within the tissue in a fashion that favors responses to pathogens while dampening responses to commensals and maintaining tissue homeostasis in physiologic conditions. In this review, the expression and activation of TLRs in mucosal epithelial cells of several sites of the human body are examined. Specifically, the oral cavity, the ear canal and eye, the airways, the gut, and the reproductive tract are discussed, along with how site-specific host defense mechanisms are implemented via TLR signaling.
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Affiliation(s)
- Ryan McClure
- Department of Microbiology, Boston University School of Medicine , Boston, MA , USA
| | - Paola Massari
- Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine , Boston, MA , USA
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Yesudhas D, Gosu V, Anwar MA, Choi S. Multiple roles of toll-like receptor 4 in colorectal cancer. Front Immunol 2014; 5:334. [PMID: 25076949 PMCID: PMC4097957 DOI: 10.3389/fimmu.2014.00334] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 07/01/2014] [Indexed: 12/14/2022] Open
Abstract
Toll-like receptor (TLR) signaling has been implicated in the inflammatory responses in intestinal epithelial cells (IECs). Such inflammatory signals mediate complex interactions between commensal bacteria and TLRs and are required for IEC proliferation, immune response, repair, and homeostasis. The upregulation of certain TLRs in colorectal cancer (CRC) tissues suggests that TLRs may play an essential role in the prognosis of chronic and inflammatory diseases that ultimately culminate in CRC. Here, we provide a comprehensive review of the literature on the involvement of the TLR pathway in the initiation, progression, and metastasis of CRC, as well as inherited genetic variation and epigenetic regulation. The differential expression of TLRs in epithelial cells has also been discussed. In particular, we emphasize the physiological role of TLR4 in CRC development and pathogenesis, and propose novel and promising approaches for CRC therapeutics with the aid of TLR ligands.
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Affiliation(s)
- Dhanusha Yesudhas
- Department of Molecular Science and Technology, Ajou University , Suwon , South Korea
| | - Vijayakumar Gosu
- Department of Molecular Science and Technology, Ajou University , Suwon , South Korea
| | - Muhammad Ayaz Anwar
- Department of Molecular Science and Technology, Ajou University , Suwon , South Korea
| | - Sangdun Choi
- Department of Molecular Science and Technology, Ajou University , Suwon , South Korea
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46
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Yang Z, Sun D, Yan Z, Reynolds AB, Christman JW, Minshall RD, Malik AB, Zhang Y, Hu G. Differential role for p120-catenin in regulation of TLR4 signaling in macrophages. THE JOURNAL OF IMMUNOLOGY 2014; 193:1931-41. [PMID: 25015829 DOI: 10.4049/jimmunol.1302863] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Activation of TLR signaling through recognition of pathogen-associated molecular patterns is essential for the innate immune response against bacterial and viral infections. We have shown that p120-catenin (p120) suppresses TLR4-mediated NF-кB signaling in LPS-challenged endothelial cells. In this article, we report that p120 differentially regulates LPS/TLR4 signaling in mouse bone marrow-derived macrophages. We observed that p120 inhibited MyD88-dependent NF-κB activation and release of TNF-α and IL-6, but enhanced TIR domain-containing adapter-inducing IFN-β-dependent IFN regulatory factor 3 activation and release of IFN-β upon LPS exposure. p120 silencing diminished LPS-induced TLR4 internalization, whereas genetic and pharmacological inhibition of RhoA GTPase rescued the decrease in endocytosis of TLR4 and TLR4-MyD88 signaling, and reversed the increase in TLR4-TIR domain-containing adapter-inducing IFN-β signaling induced by p120 depletion. Furthermore, we demonstrated that altered p120 expression in macrophages regulates the inflammatory phenotype of LPS-induced acute lung injury. These results indicate that p120 functions as a differential regulator of TLR4 signaling pathways by facilitating TLR4 endocytic trafficking in macrophages, and support a novel role for p120 in influencing the macrophages in the lung inflammatory response to endotoxin.
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Affiliation(s)
- Zhiyong Yang
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL 60612
| | - Dong Sun
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL 60612; Department of General Surgery, Qilu Hospital of Shandong University, Jinan, 250012 China
| | - Zhibo Yan
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL 60612; Department of General Surgery, Qilu Hospital of Shandong University, Jinan, 250012 China
| | - Albert B Reynolds
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232
| | - John W Christman
- Department of Medicine, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210; and
| | - Richard D Minshall
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL 60612; Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60612
| | - Asrar B Malik
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60612
| | - Yang Zhang
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL 60612
| | - Guochang Hu
- Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL 60612; Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60612
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Chakraborty S, Chaudhuri D, Balakrishnan A, Chakravortty D. Salmonella methylglyoxal detoxification by STM3117-encoded lactoylglutathione lyase affects virulence in coordination with Salmonella pathogenicity island 2 and phagosomal acidification. MICROBIOLOGY-SGM 2014; 160:1999-2017. [PMID: 24961952 DOI: 10.1099/mic.0.078998-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Intracellular pathogens such as Salmonella enterica serovar Typhimurium (S. Typhimurium) manipulate their host cells through the interplay of various virulence factors. A multitude of such virulence factors are encoded on the genome of S. Typhimurium and are usually organized in pathogenicity islands. The virulence-associated genomic stretch of STM3117-3120 has structural features of pathogenicity islands and is present exclusively in non-typhoidal serovars of Salmonella. It encodes metabolic enzymes predicted to be involved in methylglyoxal metabolism. STM3117-encoded lactoylglutathione lyase significantly impacts the proliferation of intracellular Salmonella. The deletion mutant of STM3117 (Δlgl) fails to grow in epithelial cells but hyper-replicates in macrophages. This difference in proliferation outcome was the consequence of failure to detoxify methylglyoxal by Δlgl, which was also reflected in the form of oxidative DNA damage and upregulation of kefB in the mutant. Within macrophages, the toxicity of methylglyoxal adducts elicits the potassium efflux channel (KefB) in the mutant which subsequently modulates the acidification of mutant-containing vacuoles (MCVs). The perturbation in the pH of the MCV milieu and bacterial cytosol enhances the Salmonella pathogenicity island 2 translocation in Δlgl, increasing its net growth within macrophages. In epithelial cells, however, the maturation of Δlgl-containing vacuoles were affected as these non-phagocytic cells maintain less acidic vacuoles compared to those in macrophages. Remarkably, ectopic expression of Toll-like receptors 2 and 4 on epithelial cells partially restored the survival of Δlgl. This study identified a novel metabolic enzyme in S. Typhimurium whose activity during intracellular infection within a given host cell type differentially affected the virulence of the bacteria.
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Affiliation(s)
- Sangeeta Chakraborty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Debalina Chaudhuri
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Arjun Balakrishnan
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
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Parlato M, Yeretssian G. NOD-like receptors in intestinal homeostasis and epithelial tissue repair. Int J Mol Sci 2014; 15:9594-627. [PMID: 24886810 PMCID: PMC4100112 DOI: 10.3390/ijms15069594] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/16/2014] [Accepted: 05/20/2014] [Indexed: 12/13/2022] Open
Abstract
The intestinal epithelium constitutes a dynamic physical barrier segregating the luminal content from the underlying mucosal tissue. Following injury, the epithelial integrity is restored by rapid migration of intestinal epithelial cells (IECs) across the denuded area in a process known as wound healing. Hence, through a sequence of events involving restitution, proliferation and differentiation of IECs the gap is resealed and homeostasis reestablished. Relapsing damage followed by healing of the inflamed mucosa is a hallmark of several intestinal disorders including inflammatory bowel diseases (IBD). While several regulatory peptides, growth factors and cytokines stimulate restitution of the epithelial layer after injury, recent evidence in the field underscores the contribution of innate immunity in controlling this process. In particular, nucleotide-binding and oligomerization domain-like receptors (NLRs) play critical roles in sensing the commensal microbiota, maintaining homeostasis, and regulating intestinal inflammation. Here, we review the process of intestinal epithelial tissue repair and we specifically focus on the impact of NLR-mediated signaling mechanisms involved in governing epithelial wound healing during disease.
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Affiliation(s)
- Marianna Parlato
- Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Garabet Yeretssian
- Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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49
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Kay E, Scotland RS, Whiteford JR. Toll-like receptors: Role in inflammation and therapeutic potential. Biofactors 2014; 40:284-94. [PMID: 24375529 DOI: 10.1002/biof.1156] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 11/13/2013] [Accepted: 11/24/2013] [Indexed: 01/09/2023]
Abstract
Inflammation is an essential process in response to injury and infection. However, under certain circumstances dis-regulation of this process can lead to pathologies such as rheumatoid arthritis, atherosclerosis, lupus, and is a contributory factor in the progression of many cancers. The Toll-like family of receptors (TLRs) has major roles in the initiation of the inflammatory response and as such has attracted much focus for their potential as therapeutic targets. Here we review the role of TLRs in the inflammatory response and associated disease and examine how this important family of molecules might be targeted for therapeutic benefit.
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Affiliation(s)
- Emma Kay
- Centre for Microvascular Research, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, UK
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50
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Pathogenesis of human enterovirulent bacteria: lessons from cultured, fully differentiated human colon cancer cell lines. Microbiol Mol Biol Rev 2014; 77:380-439. [PMID: 24006470 DOI: 10.1128/mmbr.00064-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hosts are protected from attack by potentially harmful enteric microorganisms, viruses, and parasites by the polarized fully differentiated epithelial cells that make up the epithelium, providing a physical and functional barrier. Enterovirulent bacteria interact with the epithelial polarized cells lining the intestinal barrier, and some invade the cells. A better understanding of the cross talk between enterovirulent bacteria and the polarized intestinal cells has resulted in the identification of essential enterovirulent bacterial structures and virulence gene products playing pivotal roles in pathogenesis. Cultured animal cell lines and cultured human nonintestinal, undifferentiated epithelial cells have been extensively used for understanding the mechanisms by which some human enterovirulent bacteria induce intestinal disorders. Human colon carcinoma cell lines which are able to express in culture the functional and structural characteristics of mature enterocytes and goblet cells have been established, mimicking structurally and functionally an intestinal epithelial barrier. Moreover, Caco-2-derived M-like cells have been established, mimicking the bacterial capture property of M cells of Peyer's patches. This review intends to analyze the cellular and molecular mechanisms of pathogenesis of human enterovirulent bacteria observed in infected cultured human colon carcinoma enterocyte-like HT-29 subpopulations, enterocyte-like Caco-2 and clone cells, the colonic T84 cell line, HT-29 mucus-secreting cell subpopulations, and Caco-2-derived M-like cells, including cell association, cell entry, intracellular lifestyle, structural lesions at the brush border, functional lesions in enterocytes and goblet cells, functional and structural lesions at the junctional domain, and host cellular defense responses.
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