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Monteiro R, Chafsey I, Caccia N, Ageorges V, Leroy S, Viala D, Hébraud M, Livrelli V, Pizza M, Pezzicoli A, Desvaux M. Specific Proteomic Identification of Collagen-Binding Proteins in Escherichia coli O157:H7: Characterisation of OmpA as a Potent Vaccine Antigen. Cells 2023; 12:1634. [PMID: 37371104 DOI: 10.3390/cells12121634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/02/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Escherichia coli is a versatile commensal species of the animal gut that can also be a pathogen able to cause intestinal and extraintestinal infections. The plasticity of its genome has led to the evolution of pathogenic strains, which represent a threat to global health. Additionally, E. coli strains are major drivers of antibiotic resistance, highlighting the urgent need for new treatment and prevention measures. The antigenic and structural heterogeneity of enterohaemorrhagic E. coli colonisation factors has limited their use for the development of effective and cross-protective vaccines. However, the emergence of new strains that express virulence factors deriving from different E. coli diarrhoeagenic pathotypes suggests that a vaccine targeting conserved proteins could be a more effective approach. In this study, we conducted proteomics analysis and functional protein characterisation to identify a group of proteins potentially involved in the adhesion of E. coli O157:H7 to the extracellular matrix and intestinal epithelial cells. Among them, OmpA has been identified as a highly conserved and immunogenic antigen, playing a significant role in the adhesion phenotype of E. coli O157:H7 and in bacterial aggregation. Furthermore, antibodies raised against recombinant OmpA effectively reduced the adhesion of E. coli O157:H7 to intestinal epithelial cells. The present work highlights the role of OmpA as a potent antigen for the development of a vaccine against intestinal pathogenic E. coli.
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Affiliation(s)
- Ricardo Monteiro
- INRAE, UCA, UMR0454 MEDIS, 63000 Clermont-Ferrand, France
- GSK, 53100 Siena, Italy
- Instituto de Investigação e Inovação em Saúde-i3S, Universidade do Porto, 4150-564 Porto, Portugal
| | - Ingrid Chafsey
- INRAE, UCA, UMR0454 MEDIS, 63000 Clermont-Ferrand, France
| | - Nelly Caccia
- INRAE, UCA, UMR0454 MEDIS, 63000 Clermont-Ferrand, France
| | | | - Sabine Leroy
- INRAE, UCA, UMR0454 MEDIS, 63000 Clermont-Ferrand, France
| | - Didier Viala
- INRAE, Metabolism Exploration Platform, Proteomic Component (PFEMcp), 63122 Saint-Genès Champanelle, France
| | - Michel Hébraud
- INRAE, UCA, UMR0454 MEDIS, 63000 Clermont-Ferrand, France
- INRAE, Metabolism Exploration Platform, Proteomic Component (PFEMcp), 63122 Saint-Genès Champanelle, France
| | | | - Mariagrazia Pizza
- GSK, 53100 Siena, Italy
- Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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2
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Peterson RJ, Koval M. Above the Matrix: Functional Roles for Apically Localized Integrins. Front Cell Dev Biol 2021; 9:699407. [PMID: 34485286 PMCID: PMC8414885 DOI: 10.3389/fcell.2021.699407] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 07/23/2021] [Indexed: 12/14/2022] Open
Abstract
Integrins are transmembrane proteins that are most typically thought of as integrating adhesion to the extracellular matrix with intracellular signaling and cell regulation. Traditionally, integrins are found at basolateral and lateral cell surfaces where they facilitate binding to the ECM and intercellular adhesion through cytosolic binding partners that regulate organization of actin microfilaments. However, evidence is accumulating that integrins also are apically localized, either endogenously or due to an exogenous stimulus. Apically localized integrins have been shown to regulate several processes by interacting with proteins such as connexins, tight junction proteins, and polarity complex proteins. Integrins can also act as receptors to mediate endocytosis. Here we review these newly appreciated roles for integrins localized to the apical cell surface.
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Affiliation(s)
- Raven J Peterson
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States
| | - Michael Koval
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States.,Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
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3
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Kaur D, Mukhopadhaya A. Outer membrane protein OmpV mediates Salmonella enterica serovar typhimurium adhesion to intestinal epithelial cells via fibronectin and α1β1 integrin. Cell Microbiol 2020; 22:e13172. [PMID: 32017350 DOI: 10.1111/cmi.13172] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 01/19/2020] [Accepted: 01/20/2020] [Indexed: 12/11/2022]
Abstract
Salmonella typhimurium is an invasive Gram-negative enteric bacterium, which causes salmonellosis, a type of gastroenteritis in humans and typhoid-like symptoms in mice. Upon entering through the contaminated food and water, S. typhimurium adheres, colonises, and invades intestinal epithelial cells (IECs) of the small intestine. In this study, we have shown that upon deletion of the outer membrane protein OmpV, there is a significant decrease in adherence of S. typhimurium to the IECs, indicating that OmpV is an important adhesin of S. typhimurium. Further, our study showed that OmpV binds to the extracellular matrix component fibronectin and signals through α1β1 integrin receptor on the IECs and OmpV-mediated activation of α1β1, resulting in the activation of focal adhesion kinase and F-actin modulation. Actin modulation is crucial for bacterial invasion. To the best of our knowledge, this is the first report of an adhesin mediated its effect through integrin in S. typhimurium. Further, we have observed a decrease in pathogenicity in terms of increased LD50 dose, lesser bacterial numbers in stool, and less colonisation of bacteria in different organs of mice infected with Δompv mutant compared with the wild-type bacteria, thus confirming the crucial role of OmpV in the pathogenesis of S. typhimurium.
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Affiliation(s)
- Deepinder Kaur
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sahibzada Ajit Singh Nagar, India
| | - Arunika Mukhopadhaya
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sahibzada Ajit Singh Nagar, India
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4
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Bhalla M, Hui Yeoh J, Lamneck C, Herring SE, Tchalla EYI, Heinzinger LR, Leong JM, Bou Ghanem EN. A1 adenosine receptor signaling reduces Streptococcus pneumoniae adherence to pulmonary epithelial cells by targeting expression of platelet-activating factor receptor. Cell Microbiol 2019; 22:e13141. [PMID: 31709673 DOI: 10.1111/cmi.13141] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/24/2019] [Accepted: 11/01/2019] [Indexed: 12/11/2022]
Abstract
Extracellular adenosine production is crucial for host resistance against Streptococcus pneumoniae (pneumococcus) and is thought to affect antibacterial immune responses by neutrophils. However, whether extracellular adenosine alters direct host-pathogen interaction remains unexplored. An important determinant for lung infection by S. pneumoniae is its ability to adhere to the pulmonary epithelium. Here we explored whether extracellular adenosine can directly impact bacterial adherence to lung epithelial cells. We found that signaling via A1 adenosine receptor significantly reduced the ability of pneumococci to bind human pulmonary epithelial cells. A1 receptor signaling blocked bacterial binding by reducing the expression of platelet-activating factor receptor, a host protein used by S. pneumoniae to adhere to host cells. In vivo, A1 was required for control of pneumococcal pneumonia as inhibiting it resulted in increased host susceptibility. As S. pneumoniae remain a leading cause of community-acquired pneumonia in the elderly, we explored the role of A1 in the age-driven susceptibility to infection. We found no difference in A1 pulmonary expression in young versus old mice. Strikingly, triggering A1 signaling boosted host resistance of old mice to S. pneumoniae pulmonary infection. This study demonstrates a novel mechanism by which extracellular adenosine modulates resistance to lung infection by targeting bacterial-host interactions.
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Affiliation(s)
- Manmeet Bhalla
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Jun Hui Yeoh
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Claire Lamneck
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Sydney E Herring
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Essi Y I Tchalla
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - Lauren R Heinzinger
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
| | - John M Leong
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Elsa N Bou Ghanem
- Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York
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5
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Paxman JJ, Lo AW, Sullivan MJ, Panjikar S, Kuiper M, Whitten AE, Wang G, Luan CH, Moriel DG, Tan L, Peters KM, Phan MD, Gee CL, Ulett GC, Schembri MA, Heras B. Unique structural features of a bacterial autotransporter adhesin suggest mechanisms for interaction with host macromolecules. Nat Commun 2019; 10:1967. [PMID: 31036849 PMCID: PMC6488583 DOI: 10.1038/s41467-019-09814-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 03/28/2019] [Indexed: 12/31/2022] Open
Abstract
Autotransporters are the largest family of outer membrane and secreted proteins in Gram-negative bacteria. Most autotransporters are localised to the bacterial surface where they promote colonisation of host epithelial surfaces. Here we present the crystal structure of UpaB, an autotransporter that is known to contribute to uropathogenic E. coli (UPEC) colonisation of the urinary tract. We provide evidence that UpaB can interact with glycosaminoglycans and host fibronectin. Unique modifications to its core β-helical structure create a groove on one side of the protein for interaction with glycosaminoglycans, while the opposite face can bind fibronectin. Our findings reveal far greater diversity in the autotransporter β-helix than previously thought, and suggest that this domain can interact with host macromolecules. The relevance of these interactions during infection remains unclear.
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Affiliation(s)
- Jason J Paxman
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, 3086, VIC, Australia
| | - Alvin W Lo
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Matthew J Sullivan
- School of Medical Science, and Menzies Health Institute Queensland, Griffith University, Gold Coast, 4222, QLD, Australia
| | - Santosh Panjikar
- Macromolecular Crystallography, Australian Synchrotron, Clayton, 3168, VIC, Australia
- Department of Molecular Biology and Biochemistry, Monash University, Melbourne, 3800, VIC, Australia
| | - Michael Kuiper
- Molecular & Materials Modelling group Data61, CSIRO, Docklands, Melbourne, 8012, VIC, Australia
| | - Andrew E Whitten
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, 2234, NSW, Australia
| | - Geqing Wang
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, 3086, VIC, Australia
| | - Chi-Hao Luan
- High Throughput Analysis Laboratory and Department of Molecular Biosciences, Northwestern University, Chicago, 60208, IL, USA
| | - Danilo G Moriel
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Lendl Tan
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Kate M Peters
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Minh-Duy Phan
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Christine L Gee
- Macromolecular Crystallography, Australian Synchrotron, Clayton, 3168, VIC, Australia
| | - Glen C Ulett
- School of Medical Science, and Menzies Health Institute Queensland, Griffith University, Gold Coast, 4222, QLD, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, 4072, QLD, Australia.
| | - Begoña Heras
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, 3086, VIC, Australia.
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6
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Yáñez D, Izquierdo M, Ruiz-Perez F, Nataro JP, Girón JA, Vidal RM, Farfan MJ. The Role of Fibronectin in the Adherence and Inflammatory Response Induced by Enteroaggregative Escherichia coli on Epithelial Cells. Front Cell Infect Microbiol 2016; 6:166. [PMID: 28008386 PMCID: PMC5143885 DOI: 10.3389/fcimb.2016.00166] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/15/2016] [Indexed: 11/15/2022] Open
Abstract
Enteroaggregative Escherichia coli (EAEC) infections are still one of the most important etiologic pathogens of diarrhea in children worldwide. EAEC pathogenesis comprises three stages: adherence and colonization, production of toxins, and diarrhea followed by inflammation. Previous studies have demonstrated that EAEC strains have the ability to bind to fibronectin (FN); however, the role this extracellular matrix protein plays in the inflammatory response induced by EAEC remains unknown. In this study, we postulated that FN-mediated adherence of EAEC strains to epithelial cells increases the expression of pro-inflammatory genes. To verify this hypothesis, we infected HEp-2 and HT-29 cells, in both the presence and absence of FN, with EAEC reference strain 042. We quantified IL-8 secretion and the relative expression of a set of genes regulated by the NF-κB pathway. Although FN increased EAEC adherence, no changes in IL-8 protein secretion or IL8 gene expression were observed. Similar observations were found in HEp-2 cells transfected with FN-siRNA and infected with EAEC. To evaluate the involvement of AAF/II fimbriae, we infected HEp-2 and HT-29 cells, in both the presence and absence of FN, with an EAEC 042aafA mutant strain transformed with a plasmid harboring the native aafA gene with a site-directed mutation in Lys72 residue (K72A and K72R strains). No changes in IL-8 secretion were observed. Finally, SEM immunogold assay of cells incubated with FN and infected with EAEC revealed that AAF fimbriae can bind to cells either directly or mediated by FN. Our data suggests that FN participates in AAF/II fimbriae-mediated adherence of EAEC to epithelial cells, but not in the inflammatory response of cells infected by this pathogen.
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Affiliation(s)
- Dominique Yáñez
- Centro de Estudios Moleculares, Departamento de Pediatría, Hospital Dr. Luis Calvo Mackenna, Facultad de Medicina, Universidad de Chile Santiago, Chile
| | - Mariana Izquierdo
- Centro de Estudios Moleculares, Departamento de Pediatría, Hospital Dr. Luis Calvo Mackenna, Facultad de Medicina, Universidad de Chile Santiago, Chile
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine Charlottesville, VA, USA
| | - James P Nataro
- Department of Pediatrics, University of Virginia School of Medicine Charlottesville, VA, USA
| | - Jorge A Girón
- Department of Pediatrics, University of Virginia School of Medicine Charlottesville, VA, USA
| | - Roberto M Vidal
- Programa de Microbiología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile Santiago, Chile
| | - Mauricio J Farfan
- Centro de Estudios Moleculares, Departamento de Pediatría, Hospital Dr. Luis Calvo Mackenna, Facultad de Medicina, Universidad de Chile Santiago, Chile
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7
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Hymes JP, Klaenhammer TR. Stuck in the Middle: Fibronectin-Binding Proteins in Gram-Positive Bacteria. Front Microbiol 2016; 7:1504. [PMID: 27713740 PMCID: PMC5031765 DOI: 10.3389/fmicb.2016.01504] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/08/2016] [Indexed: 11/13/2022] Open
Abstract
Fibronectin is a multidomain glycoprotein found ubiquitously in human body fluids and extracellular matrices of a variety of cell types from all human tissues and organs, including intestinal epithelial cells. Fibronectin plays a major role in the regulation of cell migration, tissue repair, and cell adhesion. Importantly, fibronectin also serves as a common target for bacterial adhesins in the gastrointestinal tract. Fibronectin-binding proteins (FnBPs) have been identified and characterized in a wide variety of host-associated bacteria. Single bacterial species can contain multiple, diverse FnBPs. In pathogens, some FnBPs contribute to virulence via host cell attachment, invasion, and interference with signaling pathways. Although FnBPs in commensal and probiotic strains are not sufficient to confer virulence, they are essential for attachment to their ecological niches. Here we describe the interaction between human fibronectin and bacterial adhesins by highlighting the FnBPs of Gram-positive pathogens and commensals. We provide an overview of the occurrence and diversity of FnBPs with a focus on the model pathogenic organisms in which FnBPs are most characterized. Continued investigation of FnBPs is needed to fully understand their divergence and specificity in both pathogens and commensals.
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Affiliation(s)
- Jeffrey P Hymes
- Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University Raleigh, NC, USA
| | - Todd R Klaenhammer
- Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University Raleigh, NC, USA
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8
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Moraes CTP, Polatto JM, Rossato SS, Izquierdo M, Munhoz DD, Martins FH, Pimenta DC, Farfan MJ, Elias WP, Barbosa ÂS, Piazza RMF. Flagellin and GroEL mediates in vitro binding of an atypical enteropathogenic Escherichia coli to cellular fibronectin. BMC Microbiol 2015; 15:278. [PMID: 26679711 PMCID: PMC4683701 DOI: 10.1186/s12866-015-0612-4] [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: 06/02/2015] [Accepted: 12/03/2015] [Indexed: 11/22/2022] Open
Abstract
Background Enteropathogenic Escherichia coli (EPEC) is distinguished mainly by the presence of EPEC adherence factor plasmid (pEAF) in typical EPEC (tEPEC) and its absence in atypical EPEC (aEPEC). The initial adherence to the intestinal mucosa is complex and mediated by adhesins other than bundle-forming pilus, which is not produced by aEPEC. Extracellular matrix (ECM) proteins of eukaryotic cells are commonly recognized by bacterial adhesins. Therefore, binding to ECM proteins may facilitate colonization, invasion and/or signaling by intestinal pathogens. Previous studies from our group demonstrated that aEPEC O26:H11 (strain BA2103) showed high binding activity to fibronectin, not shared by its counterpart, aEPEC O26:HNM. Results In the present study, using mass spectrometry after fibronectin-associated immunoprecipitation, two proteins, flagellin (50 kDa) and GroEL (52 kDa), were identified and BA2103 binding ability to fibronectin was inhibited in the presence of anti-H11 and anti-GroEL sera, but not by either naïve rabbit or other unrelated sera. It was also observed that the presence of purified flagellin inhibits adhesion of BA2103 to cellular fibronectin in a dose-dependent manner. Additionally, BA2103 GroEL is similar to the same protein of uropathogenic E. coli. Conclusions Our results suggest that flagellin may play a role in the in vitro interaction of BA2103 with cellular fibronectin, and GroEL can be an accessory protein in this process. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0612-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Claudia T P Moraes
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil
| | - Juliana M Polatto
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil
| | - Sarita S Rossato
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil
| | - Mariana Izquierdo
- Centro de Estudios Moleculares, Departamento de Pediatría, Hospital Dr. Luis Calvo Mackenna, Universidad de Chile, Santiago, Chile
| | - Danielle D Munhoz
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil
| | - Fernando H Martins
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil
| | - Daniel C Pimenta
- Laboratório de Bioquímica e Biofísica, Instituto Butantan, São Paulo, SP, Brazil
| | - Mauricio J Farfan
- Centro de Estudios Moleculares, Departamento de Pediatría, Hospital Dr. Luis Calvo Mackenna, Universidad de Chile, Santiago, Chile
| | - Waldir P Elias
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil
| | - Ângela S Barbosa
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil
| | - Roxane M F Piazza
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500 - 05503-900, São Paulo, SP, Brazil.
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9
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Coppens F, Iyyathurai J, Ruer S, Fioravanti A, Taganna J, Vereecke L, De Greve H, Remaut H. Structural and adhesive properties of the long polar fimbriae protein LpfD from adherent-invasive Escherichia coli. ACTA ACUST UNITED AC 2015; 71:1615-26. [PMID: 26249343 DOI: 10.1107/s1399004715009803] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 05/20/2015] [Indexed: 01/13/2023]
Abstract
Crohn's disease (CD) is an inflammatory bowel disease characterized by an exaggerated immune response to commensal microbiota in the intestines of patients. Metagenomic studies have identified specific bacterial species and strains with increased prevalence in CD patients, amongst which is the adherent-invasive Escherichia coli (AIEC) strain LF82. AIEC strains express long polar fimbriae (LPF), which are known to target Peyer's patches in a mouse CD model. Here, the recombinant production of a soluble, self-complemented construct of the LpfD protein of E. coli LF82 is reported and it is demonstrated that it forms the adhesive tip subunit of LPF. The LpfD crystal reveals an N-terminal adhesin domain and a C-terminal pilin domain that connects the adhesin to the minor pilus subunit LpfE. Surface topology and sequence conservation in the adhesin domain hint at a putative receptor-binding pocket as found in the Klebsiella pneumoniae MrkD and E. coli F17-G (GafD) adhesins. Immunohistostaining of murine intestinal tissue sections revealed that LpfD specifically binds to the intestinal mucosa and submucosa. LpfD binding was found to be resistant to treatment with O- or N-glycosidases, but was lost in collagenase-treated tissue sections, indicating the possible involvement of an intestinal matrix-associated protein as the LpfD receptor. LpfD strongly adhered to isolated fibronectin in an in vitro assay, and showed lower levels of binding to collagen V and laminin and no binding to collagens I, III and IV.
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Affiliation(s)
- Fanny Coppens
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Jegan Iyyathurai
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Ségolène Ruer
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Antonella Fioravanti
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Joemar Taganna
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Lars Vereecke
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, 9052 Ghent, Belgium
| | - Henri De Greve
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Han Remaut
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
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10
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Participation of integrin α5β1 in the fibronectin-mediated adherence of enteroaggregative Escherichia coli to intestinal cells. BIOMED RESEARCH INTERNATIONAL 2014; 2014:781246. [PMID: 25177698 PMCID: PMC4142158 DOI: 10.1155/2014/781246] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 07/11/2014] [Indexed: 12/21/2022]
Abstract
Adherence to the intestinal epithelia is a key feature in enteroaggregative Escherichia coli (EAEC) infection. The aggregative adherence fimbriae (AAFs) are involved in EAEC interaction with receptors at the surface of intestinal cells. We and others have demonstrated that fibronectin is a receptor for AAF/II fimbriae. Considering that the major cellular receptor of fibronectin is integrin α5β1, in this study we evaluated the participation of this receptor in the fibronectin-mediated adherence of EAEC strain 042 to intestinal cells. We found that EAEC strain 042 has the ability to bind directly and indirectly to integrin α5β1; direct binding was not mediated by AAF/II fimbriae and indirect binding was mediated by AAF/II and fibronectin. Coimmunoprecipitation assays confirmed the formation of the complex AafA/fibronectin/integrin α5β1. To evaluate EAEC adherence to intestinal cells, T84 cells were incubated with fibronectin and an antibody that blocks the interaction region of integrin α5β1 to fibronectin, the RGD site. Under these conditions, we found the number of adherent bacteria to epithelial cells significantly reduced. Additionally, fibronectin-mediated adherence of EAEC strain 042 was abolished in HEp-2 cells transfected with integrin α5 shRNA. Altogether, our data support the involvement of integrin α5β1 in the fibronectin-mediated EAEC binding to intestinal cells.
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11
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Identification of a group B streptococcal fibronectin binding protein, SfbA, that contributes to invasion of brain endothelium and development of meningitis. Infect Immun 2014; 82:2276-86. [PMID: 24643538 DOI: 10.1128/iai.01559-13] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Group B Streptococcus (GBS) is currently the leading cause of neonatal meningitis. This is due to its ability to survive and multiply in the bloodstream and interact with specialized human brain microvascular endothelial cells (hBMEC), which constitute the blood-brain barrier (BBB). The exact mechanism(s) of GBS-BBB penetration is still largely unknown. We and others have shown that GBS interacts with components of the extracellular matrix. In this study, we demonstrate that GBS of representative serotypes binds immobilized and cell surface fibronectin and identify a putative fibronectin binding protein, streptococcal fibronectin binding protein A (SfbA). Allelic replacement of sfbA in the GBS chromosome resulted in a significant decrease in ability to bind fibronection and invade hBMEC compared with the wild-type (WT) parental strain. Expression of SfbA in the noninvasive strain Lactococcus lactis was sufficient to promote fibronectin binding and hBMEC invasion. Furthermore, the addition of an antifibronectin antibody or an RGD peptide that blocks fibronectin binding to integrins significantly reduced invasion of the WT but not the sfbA-deficient mutant strain, demonstrating the importance of an SfbA-fibronectin-integrin interaction for GBS cellular invasion. Using a murine model of GBS meningitis, we also observed that WT GBS penetrated the brain and established meningitis more frequently than did the ΔsfbA mutant strain. Our data suggest that GBS SfbA plays an important role in bacterial interaction with BBB endothelium and the pathogenesis of streptococcal meningitis.
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Boll EJ, McCormick BA. A new understanding of enteroaggregative Escherichia coli as an inflammatory pathogen. Cell Adh Migr 2012; 6:413-8. [PMID: 23076052 DOI: 10.4161/cam.21241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Enteroaggregative Escherichia coli (EAEC) is an important cause of endemic and epidemic diarrheal disease worldwide. Although not classically considered an inflammatory pathogen in the style of Shigella and Salmonella species, clinical data from patients suggests that inflammatory responses may play an important role during EAEC disease. However, the specific role of inflammation during EAEC pathogenesis has not been investigated in detail. To better understand how EAEC may induce inflammation, we have focused our attention on the intimate interactions between EAEC and the host epithelium and the subsequent induction of host cell signaling events leading to innate immune responses. Here, we discuss our recent findings on the signaling pathway by which EAEC promotes transepithelial migration of polymorphonuclear leukocytes (PMNs), the role of aggregative adherence fimbriae in triggering this event and the implementation of human intestinal xenografts in immunodeficient mice for studying EAEC pathogenesis in vivo. Our findings suggest that EAEC shares conserved mechanisms of inducing PMN recruitment with other intestinal pathogens, providing new insight into the potential pathological consequences of EAEC-induced inflammation.
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Affiliation(s)
- Erik J Boll
- Department of Microbiology and Physiological Systems; University of Massachusetts Medical School; Worcester, MA, USA
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Smani Y, McConnell MJ, Pachón J. Role of fibronectin in the adhesion of Acinetobacter baumannii to host cells. PLoS One 2012; 7:e33073. [PMID: 22514602 PMCID: PMC3326023 DOI: 10.1371/journal.pone.0033073] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 02/09/2012] [Indexed: 11/29/2022] Open
Abstract
Adhesion to host cells is an initial and important step in Acinetobacter baumannii pathogenesis. However, there is relatively little information on the mechanisms by which A. baumannii binds to and interacts with host cells. Adherence to extracellular matrix proteins, such as fibronectin, affords pathogens with a mechanism to invade epithelial cells. Here, we found that A. baumannii adheres more avidly to immobilized fibronectin than to control protein. Free fibronectin used as a competitor resulted in dose-dependent decreased binding of A. baumannii to fibronectin. Three outer membrane preparations (OMPs) were identified as fibronectin binding proteins (FBPs): OMPA, TonB-dependent copper receptor, and 34 kDa OMP. Moreover, we demonstrated that fibronectin inhibition and neutralization by specific antibody prevented significantly the adhesion of A. baumannii to human lung epithelial cells (A549 cells). Similarly, A. baumannii OMPA neutralization by specific antibody decreased significantly the adhesion of A. baumannii to A549 cells. These data indicate that FBPs are key adhesins that mediate binding of A. baumannii to human lung epithelial cells through interaction with fibronectin on the surface of these host cells.
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Affiliation(s)
- Younes Smani
- Clinic Unit of Infectious Diseases, Microbiology and Preventive Medicine, Institute of Biomedicine of Seville, IBiS, University Hospital Virgen del Rocío/CSIC/University of Seville, Seville, Spain.
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Microarray Analyses of Genes Differentially Expressed by Diet (Black Beans and Soy Flour) during Azoxymethane-Induced Colon Carcinogenesis in Rats. J Nutr Metab 2012; 2012:351796. [PMID: 22496968 PMCID: PMC3306975 DOI: 10.1155/2012/351796] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 10/25/2011] [Indexed: 02/06/2023] Open
Abstract
We previously demonstrated that black bean (BB) and soy flour (SF)-based diets inhibit azoxymethane (AOM)-induced colon cancer. The objective of this study was to identify genes altered by carcinogen treatment in normal-appearing colonic mucosa and those attenuated by bean feeding. Ninety-five male F344 rats were fed control (AIN) diets upon arrival. At 4 and 5 weeks, rats were injected with AOM (15 mg/kg) or saline and one week later administered an AIN, BB-, or SF-based diet. Rats were sacrificed after 31 weeks, and microarrays were conducted on RNA isolated from the distal colonic mucosa. AOM treatment induced a number of genes involved in immunity, including several MHC II-associated antigens and innate defense genes (RatNP-3, Lyz2, Pla2g2a). BB- and SF-fed rats exhibited a higher expression of genes involved in energy metabolism and water and sodium absorption and lower expression of innate (RatNP-3, Pla2g2a, Tlr4, Dmbt1) and cell cycle-associated (Cdc2, Ccnb1, Top2a) genes. Genes involved in the extracellular matrix (Col1a1, Fn1) and innate immunity (RatNP-3, Pla2g2a) were induced by AOM in all diets, but to a lower extent in bean-fed animals. This profile suggests beans inhibit colon carcinogenesis by modulating cellular kinetics and reducing inflammation, potentially by preserving mucosal barrier function.
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Boll EJ, Struve C, Sander A, Demma Z, Krogfelt KA, McCormick BA. Enteroaggregative Escherichia coli promotes transepithelial migration of neutrophils through a conserved 12-lipoxygenase pathway. Cell Microbiol 2011; 14:120-32. [PMID: 21951973 DOI: 10.1111/j.1462-5822.2011.01706.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enteroaggregative Escherichia coli (EAEC) induces release of pro-inflammatory markers and disruption of intestinal epithelial barriers in vitro, suggesting an inflammatory aspect to EAEC infection. However, the mechanisms underlying EAEC-induced mucosal inflammatory responses and the extent to which these events contribute to pathogenesis is not well characterized. Employing an established in vitro model we demonstrated that EAEC prototype strain 042 induces migration of polymorphonuclear neutrophils (PMNs) across polarized T84 cell monolayers. This event was mediated through a conserved host cell signalling cascade involving the 12/15-LOX pathway and led to apical secretion of an arachidonic acid-derived lipid PMN chemoattractant, guiding PMNs across the epithelia to the site of infection. Moreover, supporting the hypothesis that inflammatory responses may contribute to EAEC pathogenesis, we found that PMN transepithelial migration promoted enhanced attachment of EAEC 042 to T84 cells. These findings suggest that EAEC-induced PMN infiltration may favour colonization and thus pathogenesis of EAEC.
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Affiliation(s)
- Erik J Boll
- Department of Microbiological Surveillance and Research, Statens Serum Institut, Denmark
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Long polar fimbriae of enterohemorrhagic Escherichia coli O157:H7 bind to extracellular matrix proteins. Infect Immun 2011; 79:3744-50. [PMID: 21708988 DOI: 10.1128/iai.05317-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Adherence to intestinal cells is a key process in infection caused by enterohemorrhagic Escherichia coli (EHEC). Several adhesion factors that mediate the binding of EHEC to intestinal cells have been described, but the receptors involved in their recognition are not fully characterized. Extracellular matrix (ECM) proteins might act as receptors involved in the recognition of enteric pathogens, including EHEC. In this study, we sought to characterize the binding of EHEC O157:H7 to ECM proteins commonly present in the intestine. We found that EHEC prototype strains as well as other clinical isolates adhered more abundantly to surfaces coated with fibronectin, laminin, and collagen IV. Further characterization of this phenotype, by using antiserum raised against the LpfA1 putative major fimbrial subunit and by addition of mannose, showed that a reduced binding of EHEC to ECM proteins was observed in a long polar fimbria (lpf) mutant. We also found that the two regulators, H-NS and Ler, had an effect in EHEC Lpf-mediated binding to ECM, supporting the roles of these tightly regulated fimbriae as adherence factors. Purified Lpf major subunit bound to all of the ECM proteins tested. Finally, increased bacterial adherence was observed when T84 cells, preincubated with ECM proteins, were infected with EHEC. Taken together, these findings suggest that the interaction of Lpf and ECM proteins contributes to the EHEC colonization of the gastrointestinal tract.
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Feoktistov I, Biaggioni I. Role of adenosine A(2B) receptors in inflammation. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 61:115-44. [PMID: 21586358 PMCID: PMC3748596 DOI: 10.1016/b978-0-12-385526-8.00005-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent progress in our understanding of the unique role of A(2B) receptors in the regulation of inflammation, immunity, and tissue repair was considerably facilitated with the introduction of new pharmacological and genetic tools. However, it also led to seemingly conflicting conclusions on the role of A(2B) adenosine receptors in inflammation with some publications indicating proinflammatory effects and others suggesting the opposite. This chapter reviews the functions of A(2B) receptors in various cell types related to inflammation and integrated effects of A(2B) receptor modulation in several animal models of inflammation. It is argued that translation of current findings into novel therapies would require a better understanding of A(2B) receptor functions in diverse types of inflammatory responses in various tissues and at different points of their progression.
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Affiliation(s)
- Igor Feoktistov
- Department of Medicine, Vanderbilt University, Division of Cardiovascular Medicine, Nashville, Tennessee, USA
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Mirakaj V, Gatidou D, Pötzsch C, König K, Rosenberger P. Netrin-1 Signaling Dampens Inflammatory Peritonitis. THE JOURNAL OF IMMUNOLOGY 2010; 186:549-55. [DOI: 10.4049/jimmunol.1002671] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Kolachala VL, Wang L, Obertone TS, Prasad M, Yan Y, Dalmasso G, Gewirtz AT, Merlin D, Sitaraman SV. Adenosine 2B receptor expression is post-transcriptionally regulated by microRNA. J Biol Chem 2010; 285:18184-90. [PMID: 20388705 DOI: 10.1074/jbc.m109.066555] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We have reported that epithelial adenosine 2B receptor (A(2B)AR) mRNA and protein are up-regulated in colitis, which we demonstrated to be regulated by tumor necrosis factor alpha (TNF-alpha). Here, we examined the mechanism that governs A(2B)AR expression during colitis. A 1.4-kb sequence of the A(2B)AR promoter was cloned into the pFRL7 luciferase vector. Anti-microRNA (miRNA) was custom-synthesized based on specific miRNA binding sites. The binding of miRNA to the 3'-untranslated region (UTR) of A(2B)AR mRNA was examined by cloning this 3'-UTR downstream of the luciferase gene in pMIR-REPORT. In T84 cells, TNF-alpha induced a 35-fold increase in A(2B)AR mRNA but did not increase promoter activity in luciferase assays. By nuclear run-on assay, no increase in A(2B)AR mRNA following TNF-alpha treatment was observed. Four putative miRNA target sites (miR27a, miR27b, miR128a, miR128b) in the 3'-UTR of the A(2B)AR mRNA were identified in T84 cells and mouse colon. Pretreatment of cells with TNF-alpha reduced the levels of miR27b and miR128a by 60%. Over expression of pre-miR27b and pre-miR128a reduced A(2B)AR levels by >60%. Blockade of miR27b increased A(2B)AR mRNA levels by 6-fold in vitro. miR27b levels declined significantly in colitis-affected tissue in mice in the presence of increased A(2B)AR mRNA. Collectively, these data demonstrate that TNF-alpha-induced A(2B)AR expression in colonic epithelial cells is post-transcriptionally regulated by miR27b and miR128a and show that miR27b influences A(2B)AR expression in murine colitis.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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Burkholder KM, Bhunia AK. Salmonella enterica serovar Typhimurium adhesion and cytotoxicity during epithelial cell stress is reduced by Lactobacillus rhamnosus GG. Gut Pathog 2009; 1:14. [PMID: 19589170 PMCID: PMC2716363 DOI: 10.1186/1757-4749-1-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 07/09/2009] [Indexed: 12/19/2022] Open
Abstract
Background Physiological stressors may alter susceptibility of the host intestinal epithelium to infection by enteric pathogens. In the current study, cytotoxic effect, adhesion and invasion of Salmonella enterica serovar Typhimurium (S. Typhimurium) to Caco-2 cells exposed to thermal stress (41°C, 1 h) was investigated. Probiotic bacteria have been shown to reduce interaction of pathogens with the epithelium under non-stress conditions and may have a significant effect on epithelial viability during infection; however, probiotic effect on pathogen interaction with epithelial cells under physiological stress is not known. Therefore, we investigated the influence of Lactobacillus rhamnosus GG and Lactobacillus gasseri on Salmonella adhesion and Salmonella-induced cytotoxicity of Caco-2 cells subjected to thermal stress. Results Thermal stress increased the cytotoxic effect of both S. Typhimurium (P = 0.0001) and nonpathogenic E. coli K12 (P = 0.004) to Caco-2 cells, and resulted in greater susceptibility of cell monolayers to S. Typhimurium adhesion (P = 0.001). Thermal stress had no significant impact on inflammatory cytokines released by Caco-2 cells, although exposure to S. Typhimurium resulted in greater than 80% increase in production of IL-6 and IL-8. Blocking S. Typhimurium with anti-ShdA antibody prior to exposure of Salmonella decreased adhesion (P = 0.01) to non-stressed and thermal-stressed Caco-2 cells. Pre-exposure of Caco-2 cells to L. rhamnosus GG significantly reduced Salmonella-induced cytotoxicity (P = 0.001) and Salmonella adhesion (P = 0.001) to Caco-2 cells during thermal stress, while L. gasseri had no effect. Conclusion Results suggest that thermal stress increases susceptibility of intestinal epithelial Caco-2 cells to Salmonella adhesion, and increases the cytotoxic effect of Salmonella during infection. Use of L. rhamnosus GG as a probiotic may reduce the severity of infection during epithelial cell stress. Mechanisms by which thermal stress increases susceptibility to S. Typhimurium colonization and by which L. rhamnosus GG limits the severity of infection remain to be elucidated.
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Affiliation(s)
- Kristin M Burkholder
- Molecular Food Microbiology Laboratory, Department of Food Science, 745 Agriculture Mall Drive, Purdue University, West Lafayette, Indiana 47907-2009, USA.
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Haskó G, Csóka B, Németh ZH, Vizi ES, Pacher P. A(2B) adenosine receptors in immunity and inflammation. Trends Immunol 2009; 30:263-70. [PMID: 19427267 DOI: 10.1016/j.it.2009.04.001] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 04/02/2009] [Accepted: 04/06/2009] [Indexed: 01/08/2023]
Abstract
A(2B) adenosine receptors are increasingly recognized as important orchestrators of inflammation. A(2B) receptor activation promotes the inflammatory response of mast cells, epithelial cells, smooth muscle cells and fibroblasts, thereby contributing to the pathophysiology of asthma and colitis. A(2B) receptor stimulation limits endothelial cell inflammatory responses and permeability and suppresses macrophage activation thereby preventing tissue injury after episodes of hypoxia and ischemia. A(2B) receptor stimulation also promotes the production of angiogenic cytokines by endothelial cells, mast cells and dendritic cells, aiding granuloma tissue formation and inflammatory resolution, but can also contribute to tumor growth. A(2B) receptors are, thus, potentially important pharmacological targets in treating immune system dysfunction and inflammation.
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Affiliation(s)
- György Haskó
- Department of Surgery, University of Medicine and Dentistry of New Jersey, Newark, 07103, USA.
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Characterization and studies of the cellular interaction of native colonization factor CS6 purified from a clinical isolate of enterotoxigenic Escherichia coli. Infect Immun 2009; 77:2125-35. [PMID: 19237522 DOI: 10.1128/iai.01397-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CS6 is a widely expressed colonization factor of enterotoxigenic Escherichia coli (ETEC). To date, CS6 has not been well characterized in its native state. Here, we purified CS6 for the first time from an ETEC clinical isolate. Purified CS6 was composed of two structural subunits, CssA and CssB, which were present in equal amounts and tightly linked through noncovalent, detergent-stable association. The CssA subunit was poorly immunogenic, whereas CssB was highly immunogenic. Although the predicted molecular mass of CssA is 15 kDa, the purified CssA has an effective molecular mass of 18.5 kDa due to fatty acid modification. When purified CS6 was screened for its ability to bind with different extracellular matrix proteins, fibronectin (Fn) was found to interact with CS6 as well as CssA in a dose-dependent and saturable manner. This interaction was inhibited both by a synthetic peptide corresponding to the C-terminal hydrophilic, surface-exposed region of CssA (positions 112 to 126) and by the antibody derived against this region. Enzyme-linked immunosorbent assay results showed that CssA interacted with the 70-kDa N-terminal domain of Fn. The modifications on CssA probably do not play a role in Fn binding. Preincubation of INT 407 cells with CssA, but not CssB, inhibited ETEC binding to these cells. The results suggested that CS6-expressing ETEC binds to Fn of INT 407 cells through the C-terminal region of CssA. Purified CS6 was found to colocalize with Fn along the junctions of INT 407 cells. Based on the results obtained, we propose that CS6-expressing ETEC binds to the intestinal cells through Fn for colonization.
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Kolachala VL, Vijay-Kumar M, Dalmasso G, Yang D, Linden J, Wang L, Gewirtz A, Ravid K, Merlin D, Sitaraman SV. A2B adenosine receptor gene deletion attenuates murine colitis. Gastroenterology 2008; 135:861-70. [PMID: 18601927 PMCID: PMC2632861 DOI: 10.1053/j.gastro.2008.05.049] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Revised: 05/08/2008] [Accepted: 05/15/2008] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS The A(2B) adenosine receptor (A(2B)AR) is the predominant adenosine receptor expressed in the colonic epithelia. We have previously shown that A(2B)AR mRNA and protein levels are up-regulated during colitis. In this study, we addressed the role of the A(2B)AR in the development of murine colitis and the potential mechanism underlying its effects. METHODS Dextran sodium sulfate (DSS), 2,4,6-trinitrobenzene sulfonic acid (TNBS), and Salmonella typhimurium were used to induce colitis in A(2B)AR-null mice (A(2B)AR(-/-)). Colitis was determined using established clinical and histologic scoring. Keratinocyte-derived chemokine (KC) measurements were performed using an enzyme-linked immunosorbent assay. RESULTS Colonic inflammation induced by DSS, TNBS, or S typhimurium was attenuated in A(2B)AR(-/-) compared with their wild-type counterparts. Clinical features, histologic score, and myeloperoxidase activity were significantly decreased in A(2B)AR(-/-) mice. However, A(2B)AR(-/-) showed increased susceptibility to systemic Salmonella infection. Tissue levels of the neutrophil chemokine, KC was decreased in colitic A(2B)AR(-/-) mice. In addition, flagellin-induced KC levels were attenuated in A(2B)AR(-/-) mice. Neutrophil chemotaxis in response to exogenous interleukin-8 was preserved in A(2B)AR(-/-) mice, suggesting intact neutrophil migration in response to appropriate stimuli. CONCLUSIONS These data demonstrate, for the first time, that the A(2B)AR plays a proinflammatory role in colitis. A(2B) receptor antagonism may be an effective treatment for acute inflammatory intestinal diseases such as acute flare of inflammatory bowel disease.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | | | - Guilliume Dalmasso
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | - Dan Yang
- Departments of Biochemistry and Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Joel Linden
- Department of Medicine and Cardiovascular Research Center, University of Virginia, Charlottesville, VA
| | - Lixin Wang
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | | | - Katya Ravid
- Departments of Biochemistry and Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Didier Merlin
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA
| | - Shanthi V. Sitaraman
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA,Address correspondence to: Shanthi V. Sitaraman, Division of Digestive Diseases, Room 201-F, 615, Michael Street, Whitehead Research Building, Emory University, Atlanta, GA, 30322, Phone: 404-727-2430, Fax: 404-727-5767,
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Bridger PS, Haupt S, Leiser R, Johnson GA, Burghardt RC, Tinneberg HR, Pfarrer C. Integrin Activation in Bovine Placentomes and in Caruncular Epithelial Cells Isolated from Pregnant Cows. Biol Reprod 2008; 79:274-82. [DOI: 10.1095/biolreprod.108.067637] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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The major pilin subunit of the AAF/II fimbriae from enteroaggregative Escherichia coli mediates binding to extracellular matrix proteins. Infect Immun 2008; 76:4378-84. [PMID: 18591223 DOI: 10.1128/iai.00439-08] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Enteroaggregative Escherichia coli (EAEC) adherence to human intestinal tissue is mediated by aggregative adherence fimbriae (AAF); however, the receptors involved in EAEC adherence remain uncharacterized. Adhesion to extracellular matrix proteins is commonly observed among enteric pathogens, so we addressed the hypothesis that EAEC may bind to extracellular matrix proteins commonly found in the intestine. We found that EAEC prototype strain 042 adhered more abundantly to surfaces that were precoated with the extracellular matrix proteins fibronectin, laminin, and type IV collagen. Differences in fibronectin binding of almost 2 orders of magnitude were observed between EAEC 042 and a mutant in the AAF/II major pilin gene, aafA. Purified AafA, refolded as a donor strand complementation construct, bound fibronectin in a dose-dependent manner. Addition of fibronectin to the apical surfaces of polarized T84 cell monolayers augmented EAEC 042 adherence, and this effect required expression of aafA. Finally, increased bacterial adherence was observed when apical secretion of fibronectin was induced by adenosine in polarized T84 cells. Binding to fibronectin may contribute to colonization of the gastrointestinal tract by EAEC.
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Abstract
Background and purpose: The adenosine 2B (A2B) receptor is the predominant adenosine receptor expressed in the colon. Acting through the A2B receptor, adenosine mediates chloride secretion, as well as fibronectin and interleukin (IL)-6 synthesis and secretion in intestinal epithelial cells. A2B receptor mRNA and protein expression are increased during human and murine colitis. However, the effect of the A2B receptor in the activation of the intestinal inflammatory response is not known. In this study, we examined the effect of A2B receptor antagonism on murine colitis. Experimental approach: Dextran sodium sulphate (DSS)-treated mice and piroxicam-treated IL-10−/− mice were used as animal models of colitis. The A2B receptor-selective antagonist, ATL-801, was given in the diet. Key results: Mice fed ATL-801 along with DSS showed a significantly lower extent and severity of colitis than mice treated with DSS alone, as shown by reduced clinical symptoms, histological scores, IL-6 levels and proliferation indices. The administration of ATL-801 prevented weight loss, suppressed the inflammatory infiltrate into colonic mucosa and decreased epithelial hyperplasia in piroxicam-treated IL-10−/− mice. IL-6 and keratinocyte-derived chemokine (KC) concentrations in the supernatants of colonic organ cultures from colitic mice were significantly reduced by ATL-801 administration. Conclusions and implications: Taken together, these data demonstrate that the intestinal epithelial A2B receptor is an important mediator of pro-inflammatory responses in the intestine and that A2B receptor blockade may be an effective therapeutic strategy to treat inflammatory bowel disease.
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Kolachala VL, Bajaj R, Chalasani M, Sitaraman SV. Purinergic receptors in gastrointestinal inflammation. Am J Physiol Gastrointest Liver Physiol 2008; 294:G401-10. [PMID: 18063703 DOI: 10.1152/ajpgi.00454.2007] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Purinergic receptors comprise a family of transmembrane receptors that are activated by extracellular nucleosides and nucleotides. The two major classes of purinergic receptors, P1 and P2, are expressed widely in the gastrointestinal tract as well as immune cells. The purinergic receptors serve a variety of functions from acting as neurotransmitters, to autocoid and paracrine signaling, to cell activation and immune response. Nucleosides and nucleotide agonist of purinergic receptors are released by many cell types in response to specific physiological signals, and their levels are increased during inflammation. In the past decade, the advent of genetic knockout mice and the development of highly potent and selective agonists and antagonists for the purinergic receptors have significantly advanced the understanding of purinergic receptor signaling in health and inflammation. In fact, agonist/antagonists of purinergic receptors are emerging as therapeutic modalities to treat intestinal inflammation. In this article, the distribution of the purinergic receptors in the gastrointestinal tract and their physiological and pathophysiological role in intestinal inflammation will be reviewed.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA
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Bridger P, Menge C, Leiser R, Tinneberg HR, Pfarrer C. Bovine caruncular epithelial cell line (BCEC-1) isolated from the placenta forms a functional epithelial barrier in a polarised cell culture model. Placenta 2007; 28:1110-7. [PMID: 17850864 PMCID: PMC7112451 DOI: 10.1016/j.placenta.2007.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 07/04/2007] [Accepted: 07/05/2007] [Indexed: 12/19/2022]
Abstract
In the bovine synepitheliochorial placenta key sites of fetal-maternal interaction are placentomes consisting of maternal caruncles interdigitating with fetal cotyledons. The aim of this study was to establish an epithelial cell line from caruncles of pregnant cows and to develop a model to study restricted trophoblast invasion, pathogenesis of pregnancy associated diseases and pathways of infection and transport. Primary epithelial cells were isolated, successfully subcultured for 32 passages and cryopreserved at various stages. The cultures were termed bovine caruncular epithelial cell line-1 (BCEC-1). Cytokeratin, zonula occludens-1 protein and vimentin but neither alpha-smooth muscle actin nor desmin were detected by immunofluorescence performed every 5 (+/-1) passages. These results were confirmed by Western blotting. BCEC-1 were then cultured either without matrix or on fibronectin or collagen coated Transwell polyester membrane inserts, respectively, enabling separate access to the basal or apical epithelial compartments. Transmission and scanning electron microscopy of BCEC-1 revealed ultrastructural features also observed in vivo, such as apical microvilli and junctional complexes. Transepithelial electrical resistance (TEER) was measured regularly and revealed an increase with advancing confluence in all cultures. Cultures on coated inserts reached confluence and corresponding TEER-levels at an earlier stage. In addition, the cells were tested negative for bovine virus diarrhoea (BVD) virus, but were permissive for the virus. In conclusion, the BCEC-1 cell line retained characteristics of maternal caruncular epithelial cells as observed in vivo and in primary cell cultures and thus will be a highly useful tool for future studies of pathways of invasion, fetal-maternal communication, transport and infection.
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Affiliation(s)
- P.S. Bridger
- Department of Veterinary Anatomy, Histology and Embryology, Justus-Liebig-University, Frankfurter Strasse 98, D-35392 Giessen, Germany
| | - C. Menge
- Institute for Hygiene and Infectious Diseases of Animals, Justus-Liebig-University, Frankfurter Strasse 85-89, D-35392 Giessen, Germany
| | - R. Leiser
- Department of Veterinary Anatomy, Histology and Embryology, Justus-Liebig-University, Frankfurter Strasse 98, D-35392 Giessen, Germany
| | - H.-R. Tinneberg
- Department of Obstetrics and Gynecology, Justus-Liebig-University, Klinikstrasse 32, D-35385 Giessen, Germany
| | - C.D. Pfarrer
- Department of Obstetrics and Gynecology, Justus-Liebig-University, Klinikstrasse 32, D-35385 Giessen, Germany
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29
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Kolachala VL, Bajaj R, Wang L, Yan Y, Ritzenthaler JD, Gewirtz AT, Roman J, Merlin D, Sitaraman SV. Epithelial-derived fibronectin expression, signaling, and function in intestinal inflammation. J Biol Chem 2007; 282:32965-73. [PMID: 17855340 DOI: 10.1074/jbc.m704388200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fibronectin (FN) is a multifunctional extracellular matrix protein that plays an important role in cell proliferation, adhesion, and migration. FN expression or its role in colitis is not known. The goal of this study is to characterize FN expression, regulation, and role during intestinal inflammation. Wild-type and transgenic mice expressing luciferase under the control of the human FN promoter, given water or 3% dextran sodium sulfate, were used as animal models of colitis. The Caco2-BBE model intestinal epithelial cell line was used for in vitro studies. FN protein is abundantly expressed by surface epithelial cells in the normal colon. Immunohistochemistry and luciferase assay in mice expressing the FN promoter linked to luciferase demonstrated that FN synthesis was up-regulated during colitis, during both the acute phase and the healing phase. In vitro experiments demonstrated that FN increased the expression of the FN integrin receptor alpha5beta1 in a dose- and time-dependent manner. FN also induced the expression and activation of NF-kappaB. Further, FN potentiated Caco2-BBE cell attachment and wound healing, which was inhibited by RGD peptide as well as NF-kappaB inhibitors MG-132 and 1-pyrrolidinecarbodithioic acid, ammonium salt. In conclusion, FN is abundantly expressed and synthesized by colonic epithelial cells. FN is transcriptionally up-regulated in epithelial cells during both the dextran sodium sulfate-induced colitic and the recovery phase. FN enhances cell attachment and wound healing, which is dependent on binding to the integrin receptor and the NF-kappaB signaling. Together our data show that epithelial-derived FN potentiates cell attachment and wound healing through epithelial-matrix interactions and that FN expression may have important implications for maintaining normal epithelial integrity as well as regulating epithelial response to injury during colitis.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Department of Medicine, Emory University, 615 Michael Street, Atlanta, GA 30322, USA
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30
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Kolachala VL, Obertone TS, Wang L, Merlin D, Sitaraman SV. Adenosine 2b receptor (A2bR) signals through adenylate cyclase (AC) 6 isoform in the intestinal epithelial cells. Biochim Biophys Acta Gen Subj 2006; 1760:1102-8. [PMID: 16631311 DOI: 10.1016/j.bbagen.2006.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 03/06/2006] [Accepted: 03/09/2006] [Indexed: 11/29/2022]
Abstract
Adenosine 2b receptor (A2bR), a G-protein coupled receptor positively coupled to adenylate cyclase, mediates key events such as chloride, IL-6 and fibronectin secretion in intestinal epithelial cells and is upregulated during intestinal inflammation. In order to gain insight into the overall mechanism of A2bR activation, in this study, we sought to characterize the AC isoform associated with A2bR signaling. The colonic epithelial cell line T84, expressing only the A2b subtype of adenosine receptor, and Chinese hamster ovary (CHO) cells, were used in these studies. cAMP was measured by luminometric assay and AC isoform expression was determined by Western blot, RT-PCR, isoform-specific stealth RNAi and Quantigene. T84 and CHO cells express all nine known AC isoforms. In order to characterize which AC isoform(s) are associated with A2bR, we used the differential inhibition of specific AC isoforms by calcium and nitric oxide. Pretreatment of cells with carbachol or nitric oxide donors such as S-Nitroso-N-acetylpencillamine (SNAP) and PAPANANOATE inhibited A2bR mediated increase in cAMP. Further, overexpression of AC-5 or AC-6 potentiated A2bR-mediated increases in cAMP levels. Finally, transfection with AC isoform-specific RNAi demonstrated that AC-6 but not AC-5 RNAi inhibited adenosine-induced cAMP levels. Taken together, these results suggest that A2bR mediates signaling through AC-6 isoform. Since pro-inflammatory cytokines such as interferon-gamma (IFN-gamma) modulate the expression of specific AC isoforms in the intestinal epithelia, our observation may have therapeutic implications for intestinal inflammation or diarrhea wherein aA2bR is upregulated.
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Affiliation(s)
- Vasantha L Kolachala
- Division of Digestive Diseases, Department of Medicine, Emory University, Room 201-F, 615 Michael Street, Whitehead Research Building, Atlanta, GA 30322, USA
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31
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Németh ZH, Lutz CS, Csóka B, Deitch EA, Leibovich SJ, Gause WC, Tone M, Pacher P, Vizi ES, Haskó G. Adenosine augments IL-10 production by macrophages through an A2B receptor-mediated posttranscriptional mechanism. THE JOURNAL OF IMMUNOLOGY 2006; 175:8260-70. [PMID: 16339566 PMCID: PMC2000336 DOI: 10.4049/jimmunol.175.12.8260] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Adenosine receptor ligands have anti-inflammatory effects and modulate immune responses by up-regulating IL-10 production by immunostimulated macrophages. The adenosine receptor family comprises G protein-coupled heptahelical transmembrane receptors classified into four types: A1, A2A, A2B, and A3. Our understanding of the signaling mechanisms leading to enhanced IL-10 production following adenosine receptor occupancy on macrophages is limited. In this study, we demonstrate that adenosine receptor occupancy increases IL-10 production by LPS-stimulated macrophages without affecting IL-10 promoter activity and IL-10 mRNA levels, indicating a posttranscriptional mechanism. Transfection experiments with reporter constructs containing sequences corresponding to the AU-rich 3'-untranslated region (UTR) of IL-10 mRNA confirmed that adenosine receptor activation acts by relieving the translational repressive effect of the IL-10 3'-UTR. By contrast, adenosine receptor activation failed to liberate the translational arrest conferred by the 3'-UTR of TNF-alpha mRNA. The IL-10 3'-UTR formed specific complexes with proteins present in cytoplasmic extracts of RAW 264.7 cells. Adenosine enhanced binding of proteins to a region of the IL-10 3'-UTR containing the GUAUUUAUU nonamer. The stimulatory effect of adenosine on IL-10 production was mediated through the A(2B) receptor, because the order of potency of selective agonists was 5'-N-ethylcarboxamidoadenosine (NECA) > N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) > 2-chloro-N6-cyclopentyladenosine (CCPA) = 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethyl-carboxamidoadenosine (CGS-21680). Also, the selective A2B antagonist, alloxazine, prevented the effect of adenosine. Collectively, these studies identify a novel pathway in which activation of a G protein-coupled receptor augments translation of an anti-inflammatory gene.
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Affiliation(s)
- Zoltán H. Németh
- Department of Surgery, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103
| | - Carol S. Lutz
- Departments of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103
| | - Balázs Csóka
- Department of Surgery, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103
| | - Edwin A. Deitch
- Department of Surgery, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103
| | - S. Joseph Leibovich
- Departments of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103
| | - William C. Gause
- Department of Medicine, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103
| | - Masahide Tone
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Pál Pacher
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892
| | - E. Sylvester Vizi
- Department of Pharmacology, Institute of Experimental Medicine, Budapest, Hungary
| | - György Haskó
- Department of Surgery, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103
- Address correspondence and reprint requests to Dr. György Haskó, Department of Surgery, UMDNJ-New Jersey Medical School, 185 South Orange Avenue, University Heights, Newark, NJ 07103. E-mail address:
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Dorsey CW, Laarakker MC, Humphries AD, Weening EH, Bäumler AJ. Salmonella enterica serotype Typhimurium MisL is an intestinal colonization factor that binds fibronectin. Mol Microbiol 2005; 57:196-211. [PMID: 15948960 DOI: 10.1111/j.1365-2958.2005.04666.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
MisL is an autotransporter protein encoded by Salmonella pathogenicity island 3 (SPI3). To investigate the role of MisL in Salmonella enterica serotype Typhimurium (S. Typhimurium) pathogenesis, we characterized its function during infection of mice and identified a host receptor for this adhesin. In a mouse model of S. Typhimurium intestinal persistence, a misL mutant was shed with the faeces in significantly lower numbers than the wild type and was impaired in its ability to colonize the cecum. Previous studies have implicated binding of extracellular matrix proteins as a possible mechanism for S. Typhimurium intestinal persistence. A gluthathione-S-transferase (GST) fusion protein to the MisL passenger domain (GST-MisL(29-281)) was constructed to investigate binding to extracellular matrix proteins. In a solid-phase binding assay the purified GST-MisL(29-281) fusion protein bound to fibronectin and collagen IV, but not to collagen I. MisL expression was not detected by Western blot in S. Typhimurium grown under standard laboratory conditions. However, when expression of the cloned misL gene was driven by the Escherichia coli arabinose promoter, MisL could be detected in the S. Typhimurium outer membrane by Western blot and on the bacterial cell surface by flow cytometry. Expression of MisL enabled S. Typhimurium to bind fibronectin to its cell surface, resulting in attachment to fibronectin-coated glass slides and in increased invasiveness for human epithelial cells derived from colonic carcinoma (T84 cells). These data identify MisL as an extracellular matrix adhesin involved in intestinal colonization.
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Affiliation(s)
- Caleb W Dorsey
- Department of Medical Microbiology and Immunology, College of Medicine, Texas A&M University System Health Science Center, 407 Reynolds Medical Building, College Station, TX 77843-1114, USA
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Kolachala V, Asamoah V, Wang L, Srinivasan S, Merlin D, Sitaraman SV. Interferon-gamma down-regulates adenosine 2b receptor-mediated signaling and short circuit current in the intestinal epithelia by inhibiting the expression of adenylate cyclase. J Biol Chem 2004; 280:4048-57. [PMID: 15550390 DOI: 10.1074/jbc.m409577200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adenosine is an endogenous signaling molecule that is highly up-regulated in inflammatory states. Adenosine acts through the A2b receptor, a G protein-coupled receptor that couples positively to Galpha(s) and activates adenylate cyclase. This leads to cAMP-mediated electrogenic chloride secretion in intestinal epithelia. To better understand the regulation of the A2b receptor in intestinal epithelia, we studied the effects of interferon-gamma (IFN-gamma), a potent immunomodulatory cytokine, in the T84 cell line. Pretreatment of cells with 500 units/ml IFN-gamma for 12 h inhibited an adenosine-induced short circuit current (Isc) without affecting the transepithelial resistance. Under these conditions, IFN-gamma did not inhibit the protein expression or membrane recruitment of the A2b receptor, shown to be essential for its function. Interestingly, IFN-gamma inhibited cAMP levels as well as its downstream signaling pathway as shown by the inhibition of adenosine-induced phosphorylation of cAMP response element-binding protein and protein kinase A activity. Similar studies with forskolin, a direct activator of adenylate cyclase, also demonstrated inhibition of cAMP and its downstream response by IFN-gamma. However, IFN-gamma did not affect secretory responses to the calcium-dependent secretagogue carbachol or cAMP analog 8-bromo-cAMP, indicating that normal secretory responses to adequate second messengers in IFN-gamma-treated cells are achievable. Moreover, IFN-gamma inhibited the expression of adenylate cyclase isoforms 5 and 7. In conclusion, we demonstrate that IFN-gamma down-regulates adenosine-mediated signaling possibly through the direct inhibition of adenylate cyclase expression. We propose that IFN-gamma may acutely affect global cAMP-mediated responses in the intestinal epithelia, thereby decreasing secretory responses, which may consequently aggravate inflammatory processes.
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Affiliation(s)
- Vasantha Kolachala
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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