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Chevalier G, Laveissière A, Desachy G, Barnich N, Sivignon A, Maresca M, Nicoletti C, Di Pasquale E, Martinez-Medina M, Simpson KW, Yajnik V, Sokol H, Plassais J, Strozzi F, Cervino A, Morra R, Bonny C. Blockage of bacterial FimH prevents mucosal inflammation associated with Crohn's disease. MICROBIOME 2021; 9:176. [PMID: 34425887 PMCID: PMC8383459 DOI: 10.1186/s40168-021-01135-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/01/2021] [Indexed: 05/14/2023]
Abstract
BACKGROUND An Escherichia coli (E. coli) pathotype with invasive properties, first reported by Darfeuille-Michaud and termed adherent-invasive E. coli (AIEC), was shown to be prevalent in up to half the individuals with Crohn's Disease (CD), suggesting that these bacteria could be involved in the pathophysiology of CD. Among the genes related to AIEC pathogenicity, fim has the potential to generate an inflammatory reaction from the intestinal epithelial cells and macrophages, as it interacts with TLR4, inducing the production of inflammatory cytokines independently of LPS. Therefore, targeting the bacterial adhesion of FimH-expressing bacteria seems a promising therapeutic approach, consisting of disarming bacteria without killing them, representing a selective strategy to suppress a potentially critical trigger of intestinal inflammation, without disturbing the intestinal microbiota. RESULTS We analyzed the metagenomic composition of the gut microbiome of 358 patients with CD from two different cohorts and characterized the presence of FimH-expressing bacteria. To assess the pathogenic role of FimH, we used human intestinal explants and tested a specific FimH blocker to prevent bacterial adhesion and associated inflammation. We observed a significant and disease activity-dependent enrichment of Enterobacteriaceae in the gut microbiome of patients with CD. Bacterial FimH expression was functionally confirmed in ileal biopsies from 65% of the patients with CD. Using human intestinal explants, we further show that FimH is essential for adhesion and to trigger inflammation. Finally, a specific FimH-blocker, TAK-018, inhibits bacterial adhesion to the intestinal epithelium and prevents inflammation, thus preserving mucosal integrity. CONCLUSIONS We propose that TAK-018, which is safe and well tolerated in humans, is a promising candidate for the treatment of CD and in particular in preventing its recurrence. Video abstract.
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Affiliation(s)
| | | | | | - Nicolas Barnich
- Université Clermont Auvergne, Inserm U1071, M2iSH, USC-INRA 2018, F-63000, Clermont-Ferrand, France
| | - Adeline Sivignon
- Université Clermont Auvergne, Inserm U1071, M2iSH, USC-INRA 2018, F-63000, Clermont-Ferrand, France
| | - Marc Maresca
- Aix Marseille Université, CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Cendrine Nicoletti
- Aix Marseille Université, CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Eric Di Pasquale
- Aix-Marseille Université, CNRS, INP, Institut de Neurophysiopathologie, Marseille, France
| | | | | | - Vijay Yajnik
- GI Therapeutic Area Unit, Takeda Pharmaceuticals, Cambridge, MA, 02139, USA
| | - Harry Sokol
- Gastroenterology Department, Sorbonne Université, INSERM, Centre de Recherche Saint-Antoine, CRSA, AP-HP, Saint Antoine Hospital, 75012, Paris, France
- INRA, UMR1319 Micalis & AgroParisTech, Jouy en Josas, France
- Paris Center for Microbiome Medicine (PaCeMM) FHU, AP-HP, Paris, France
| | | | | | | | - Rachel Morra
- Enterome, 94-96 Avenue Ledru-Rollin, 75011, Paris, France
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2
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Microbiota-mediated protection against antibiotic-resistant pathogens. Genes Immun 2021; 22:255-267. [PMID: 33947987 PMCID: PMC8497270 DOI: 10.1038/s41435-021-00129-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/19/2021] [Accepted: 04/09/2021] [Indexed: 02/03/2023]
Abstract
Colonization by the microbiota provides one of our most effective barriers against infection by pathogenic microbes. The microbiota protects against infection by priming immune defenses, by metabolic exclusion of pathogens from their preferred niches, and through direct antimicrobial antagonism. Disruption of the microbiota, especially by antibiotics, is a major risk factor for bacterial pathogen colonization. Restoration of the microbiota through microbiota transplantation has been shown to be an effective way to reduce pathogen burden in the intestine but comes with a number of drawbacks, including the possibility of transferring other pathogens into the host, lack of standardization, and potential disruption to host metabolism. More refined methods to exploit the power of the microbiota would allow us to utilize its protective power without the drawbacks of fecal microbiota transplantation. To achieve this requires detailed understanding of which members of the microbiota protect against specific pathogens and the mechanistic basis for their effects. In this review, we will discuss the clinical and experimental evidence that has begun to reveal which members of the microbiota protect against some of the most troublesome antibiotic-resistant pathogens: Klebsiella pneumoniae, vancomycin-resistant enterococci, and Clostridioides difficile.
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He-Yang J, Zhang W, Liu J, Xue P, Zhou X. Human breast milk oligosaccharides attenuate necrotizing enterocolitis in rats by suppressing mast cell accumulation, DPPI activity and TLR4 expression in ileum tissue, and regulating mitochondrial damage of Caco-2 cells. Int Immunopharmacol 2020; 88:106881. [PMID: 32795899 DOI: 10.1016/j.intimp.2020.106881] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/05/2020] [Accepted: 08/05/2020] [Indexed: 12/09/2022]
Abstract
Necrotizing enterocolitis (NEC), a devastating infant disease characterized by severe intestinal necrosis, its pathogenesis is poorly understood, but appears to be multifactorial and highly associated with immaturity of gastrointestinal tract and immature innate-immune system. Breast-milk is effective strategy to protect infants against NEC. This study is using a NEC rat model to investigate the pathological mechanism of NEC involved intestinal-damages, and the therapeutic mechanism of sialylated human milk oligosaccharides (SHMOs) on NEC rats; also using cell model to investigate the effects of SHMOs on colon-epithelial cells (Caco-2) in-vitro. Extraction and characterization of SHMOs from breast milk, establishment of a NEC rat model, histopathological analysis and mast cell accounting of the terminal ileum were taken; The levels of DPPI, TLR4, IL-6, TNF-α, MMP-2/9 and glutathione were measured using various methods. Caco-2 cells were pre-treated with SHMOs and cultured with LPS, histamine, chymase or DPPI, cell viabilities and mitochondrial membrane potential were examined; flow cytometry was used to detect cell cycle. The accumulation of mast cells was found in the ileum of NEC rats, but prohibited by SHMOs treatment; the increased levels of TLR4, DPPI, IL-6, TNF-α, MMP-2/9 in NEC ileum were suppressed by SHMOs in-vivo. SHMOs prevented Caco-2 cells from LPS, histamine, chymase induced damages by surviving cell viability, regulating G0/G1 and S phase in cell cycles, and increasing mitochondrial membrane potential. These findings provide a new insight into the pharmacological mechanism of SHMOs treatment for NEC and suggest that SHMOs needs well attention for therapeutic aims.
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Affiliation(s)
- Jingqiu He-Yang
- The School of Pharmacy, Changzhou University, Jiangsu 213164, China
| | - Wenting Zhang
- The School of Pharmacy, Changzhou University, Jiangsu 213164, China; Department of Pharmacy, Affiliated Changzhou Children's Hospital of Nantong University, Yanling Road 468, Changzhou 213003, China
| | - Jie Liu
- The School of Pharmacy, Changzhou University, Jiangsu 213164, China
| | - Peng Xue
- Department of Pharmacy, Affiliated Changzhou Children's Hospital of Nantong University, Yanling Road 468, Changzhou 213003, China
| | - Xiaoying Zhou
- The School of Pharmacy, Changzhou University, Jiangsu 213164, China; The School of Medicine, the University of Southampton, Southampton SO16 6YD, UK.
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4
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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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5
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Wang B, Li J, Wang S, Hao Y, Zhao X, Chen J. Lactobacillus plantarum ameliorates tumour necrosis factor-induced bacterial translocation in Caco-2 cells by regulation of TLR4 expression. J Med Microbiol 2019; 67:982-991. [PMID: 29877788 DOI: 10.1099/jmm.0.000762] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose. Translocation of bacteria across the intestinal barrier is important in the pathogenesis of systemic sepsis. In inflammatory conditions, commensal bacteria exploit transcytotic pathways to cross the intestinal epithelium in a TLR4-dependent manner. The aim of this study was to test the hypothesis that Lactobacillus plantarum ameliorates tumour necrosis factor-induced bacterial translocation by regulation of Toll-like receptor-4 expression.Methodology. L. plantarum strains were investigated to determine their capacity to inhibit the initial adhesion of Escherichia coli B5 to Caco-2 cells. The inhibitory effects of L. plantarum on TNF-α-induced E. coli B5 translocation across Caco-2 cells were studied. Barrier function and integrity were simultaneously assessed by transepithelial electrical resistance, HRP permeability, LDH release and distribution of tight junctional proteins. Expression of TLR4 was assessed by RT-PCR.Results/Key findings. Pretreatment of monolayers with L. plantarum L2 led to a significant decrease in E. coli B5 adhesion and cell internalization (P<0.01). Exposure to TNF-α for six hours caused a significant increase in E. coli B5 translocation across Caco-2 cells, which was uncoupled from increases in paracellular permeability and disruption of tight junction proteins. Manipulations that induced bacterial translocation were associated with a marked increase in TLR4 mRNA expression and IL-8 secretion. L. plantarum L2 significantly abrogated TNF-α-induced bacterial translocation of E. coli B5, and also downregulated expression of TLR4 and IL-8 in intestinal epithelial cells.Conclusion. Live L. plantarum L2 can inhibit TNF-α-induced transcellular bacterial translocation via regulation of TLR4 expression.
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Affiliation(s)
- Bin Wang
- Jiangsu Academy of Science and Technology for Inspection and Quarantine, Nanjing, Jiangsu 210001, PR China.,Department of Travel Health, Nanjing Entry-Exit Inspection and Quarantine Bureau, Nanjing, Jiangsu 211106, PR China
| | - Jingjing Li
- Department of Ultrasound, Nanjing Hospital of Armed Police Force Corps, Nanjing, Jiangsu 210028, PR China
| | - Shuiming Wang
- Department of Travel Health, Nanjing Entry-Exit Inspection and Quarantine Bureau, Nanjing, Jiangsu 211106, PR China
| | - Yu Hao
- Department of Travel Health, Nanjing Entry-Exit Inspection and Quarantine Bureau, Nanjing, Jiangsu 211106, PR China
| | - Xiaoyan Zhao
- Department of Travel Health, Nanjing Entry-Exit Inspection and Quarantine Bureau, Nanjing, Jiangsu 211106, PR China
| | - Jun Chen
- Research Institute of General Surgery, Jinling Hospital, Nanjing, Jiangsu 210002, PR China
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Korneev KV, Sviriaeva EN, Mitkin NA, Gorbacheva AM, Uvarova AN, Ustiugova AS, Polanovsky OL, Kulakovskiy IV, Afanasyeva MA, Schwartz AM, Kuprash DV. Minor C allele of the SNP rs7873784 associated with rheumatoid arthritis and type-2 diabetes mellitus binds PU.1 and enhances TLR4 expression. Biochim Biophys Acta Mol Basis Dis 2019; 1866:165626. [PMID: 31785408 DOI: 10.1016/j.bbadis.2019.165626] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 11/08/2019] [Accepted: 11/26/2019] [Indexed: 12/19/2022]
Abstract
Toll-like receptor 4 (TLR4) is an innate immunity receptor predominantly expressed on myeloid cells and involved in the development of various diseases, many of them with complex genetics. Here we present data on functionality of single nucleotide polymorphism rs7873784 located in the 3'-untranslated region (3'-UTR) of TLR4 gene and associated with various pathologies involving chronic inflammation. We demonstrate that TLR4 3'-UTR strongly enhanced the activity of TLR4 promoter in U937 human monocytic cell line while minor rs7873784(C) allele created a binding site for transcription factor PU.1 (encoded by SPI1 gene), a known regulator of TLR4 expression. Increased binding of PU.1 further augmented the TLR4 transcription while PU.1 knockdown or complete disruption of the PU.1 binding site abrogated the effect. We hypothesize that additional functional PU.1 site may increase TLR4 expression in individuals carrying minor C variant of rs7873784 and modulate the development of certain pathologies, such as rheumatoid arthritis and type-2 diabetes mellitus.
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Affiliation(s)
- Kirill V Korneev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Ekaterina N Sviriaeva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Nikita A Mitkin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Alisa M Gorbacheva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; Biological Faculty, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Aksinya N Uvarova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; Biological Faculty, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Alina S Ustiugova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; Biological Faculty, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Oleg L Polanovsky
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Ivan V Kulakovskiy
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia; Institute of Mathematical Problems of Biology, Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Marina A Afanasyeva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Anton M Schwartz
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Dmitry V Kuprash
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; Biological Faculty, Lomonosov Moscow State University, 119234 Moscow, Russia.
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7
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Bagheri M, Zahmatkesh A. Evolution and species-specific conservation of toll-like receptors in terrestrial vertebrates. Int Rev Immunol 2018; 37:217-228. [DOI: 10.1080/08830185.2018.1506780] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Masoumeh Bagheri
- Department of Genomics and Genetic Engineering, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Azadeh Zahmatkesh
- Department of Genomics and Genetic Engineering, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
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8
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Hamonic G, Pasternak JA, Wilson HL. Recognizing conserved non-canonical localization patterns of toll-like receptors in tissues and across species. Cell Tissue Res 2018; 372:1-11. [PMID: 29330675 DOI: 10.1007/s00441-017-2767-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 11/28/2017] [Indexed: 12/30/2022]
Abstract
Toll-like receptors (TLR) 1, 2, 4, 5 and 6 were originally characterized as exclusively expressed on the cell surface and TLR 3, 7, 8 and 9 were said to be localized to the endosomes. However, continued research in this area shows that TLR localization may be altered across cell-types, and in response to stimulation, age or disease. Mucosal surfaces must remain tolerant to the commensal flora and thus intracellular or basal lateral localization of TLRs at mucosal surfaces may be necessary to prevent induction of an inflammatory response to commensal flora while still allowing the possibility for the receptors to prime an immune response when a pathogen has crossed the epithelial barrier. Here, we highlight the research specifying 'non-canonical' localization of TLRs in human and animal mucosal tissues and blood-derived cells, while excluding cultured polarized immortalized cells. Reports that only indicate TLR gene/protein expression and/or responsiveness to agonists have been excluded unless the report also indicates surface/intracellular distribution in the cell. Understanding the tissue- and species-specific localization of these specific pattern recognition receptors will lead to a greater appreciation of the way in which TLR ligands promote innate immunity and influence the adaptive immune response. A more comprehensive understanding of this information will potentially aid in the exploitation of the therapeutic or adjuvant potential of selectively localized TLRs and in opening new perspectives in understanding the basis of immunity.
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Affiliation(s)
- Glenn Hamonic
- Vaccine & Infectious Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr. Saskatoon, Saskatoon, SK, S7N 5B4, Canada
| | - J Alex Pasternak
- Vaccine & Infectious Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada
| | - Heather L Wilson
- Vaccine & Infectious Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada.
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr. Saskatoon, Saskatoon, SK, S7N 5B4, Canada.
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9
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Hui L, Dai Y, Guo Z, Zhang J, Zheng F, Bian X, Wu Z, Jiang Q, Guo M, Ma K, Zhang J. Immunoregulation effects of different γδT cells and toll-like receptor signaling pathways in neonatal necrotizing enterocolitis. Medicine (Baltimore) 2017; 96:e6077. [PMID: 28225489 PMCID: PMC5569415 DOI: 10.1097/md.0000000000006077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The aim of the study was to observe cytokine and T-cell-related toll-like-receptor (TLR) changes in intestinal samples of neonatal necrotizing enterocolitis patients.Four necrotic bowels were collected from neonatal NEC patients with gestational ages of 28 to 29 weeks in our hospital, whereas 4 neonatal patients who underwent intestinal atresia surgery served as the controls. Intestinal flora was examined and IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α, IFN-γ, and IL-17 expressions in resected intestine samples, as well as in isolated gamma delta T (γδT) cells, were analyzed immunohistochemically and via quantitative RT-PCR. γδT cells were isolated from the intestinal intraepithelial lymphocytes (IELs) and their TLR4/TLR9 distribution in the intestinal tissues was determined by flow cytometry.The bacterial flora of the neonatal NEC patients' contained significantly higher amounts of Gram-negative Enterobacteriaceae, Klebsiella, and Bacteroides but anaerobic Gram-positive Bifidobacteria occurred significantly less in the NEC than the control group. IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α, IFN-γ, and IL-17 expressions in the resected intestine samples and in isolated γδT cells were enhanced in NEC samples compared to the controls. γδT cells were less prevalent in NEC-derived intestinal tissues, but their TLR4/TLR9 expressions were significantly enhanced.The changed bacterial flora in preterm neonatal NEC patients led to an obvious inflammation of the intestines, which was accompanied by reductions of γδT cell localizations to the intestine and a shift of their surface expressions to TLR4 and TLR9.
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MESH Headings
- Bacteria/isolation & purification
- Enterocolitis, Necrotizing/immunology
- Enterocolitis, Necrotizing/microbiology
- Enterocolitis, Necrotizing/pathology
- Enterocolitis, Necrotizing/surgery
- Flow Cytometry
- Humans
- Immunohistochemistry
- Infant, Newborn
- Interferon-gamma/metabolism
- Interleukins/metabolism
- Intestinal Atresia/immunology
- Intestinal Atresia/microbiology
- Intestinal Atresia/pathology
- Intestinal Atresia/surgery
- Intestine, Large/immunology
- Intestine, Large/microbiology
- Intestine, Large/pathology
- Intestine, Large/surgery
- Intestine, Small/immunology
- Intestine, Small/microbiology
- Intestine, Small/pathology
- Intestine, Small/surgery
- Polymerase Chain Reaction
- Receptors, Antigen, T-Cell, gamma-delta
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Toll-Like Receptor 4/metabolism
- Toll-Like Receptor 9/metabolism
- Tumor Necrosis Factor-alpha/metabolism
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Affiliation(s)
- Lei Hui
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Yi Dai
- Department of Neonatology, Children's Hospital of Fudan University
| | - Zhi Guo
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Jiahui Zhang
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Fang Zheng
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Xiangli Bian
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Zhimin Wu
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Qin Jiang
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Miaomiao Guo
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
| | - Ke Ma
- Emergency Department, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City, Shanghai, China
| | - Jinping Zhang
- Department of Pediatrics, Shanghai 6th People's East Hospital, Jiao Tong University, Pudong Nanhui New City
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Abad B, Mesonero J, Salvador M, Garcia-Herrera J, Rodriguez-Yoldi M. Cellular mechanism underlying LPS-induced inhibition of in vitro L-leucine transport across rabbit jejunum. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519020080020601] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Lipopolysaccharide(LPS) is a known causative agent of sepsis. In previous studies, we have shown that it reduces L-leucine mediated transport across the rabbit jejunum by about 30%. In this study, the mechanism(s) of LPS inhibition on amino acid transport were analysed in detail. LPS did not inhibit L-leucine transport across brush border membrane vesicles, suggesting the need for an intracellular step. The inhibitory effect of LPS was not altered by the addition of protein kinase A (PKA) inhibitor (IP20, 10—7M) or an analog of cAMP (DB-cAMP, 3 × 10—4M), indicating that the PKA signal transduction pathway was not involved in the LPS effect. However, the inhibitory effect of LPS was suppressed by trifluoroperazine (10—7M), a Ca2+/calmodulin inhibitor and staurosporine (10—7M), an protein kinase C (PKC) inhibitor. Likewise, LPS inhibition disappeared in media without calcium. These results suggest that LPS could inhibit the intestinal uptake of L-leucine across the small intestine in vitro by intracellular processes related to calcium, involving PKC and calmodulin protein.
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Affiliation(s)
- B. Abad
- Physiology Unit, Department of Pharmacology and Physiology, Veterinary Faculty, University of Zaragoza, Zaragoza, Spain
| | - J.E. Mesonero
- Physiology Unit, Department of Pharmacology and Physiology, Veterinary Faculty, University of Zaragoza, Zaragoza, Spain
| | - M.T. Salvador
- Physiology Unit, Department of Pharmacology and Physiology, Veterinary Faculty, University of Zaragoza, Zaragoza, Spain
| | - J. Garcia-Herrera
- Physiology Unit, Department of Pharmacology and Physiology, Veterinary Faculty, University of Zaragoza, Zaragoza, Spain
| | - M.J. Rodriguez-Yoldi
- Physiology Unit, Department of Pharmacology and Physiology, Veterinary Faculty, University of Zaragoza, Zaragoza, Spain,
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11
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Abreu MT, Thomas LS, Arnold ET, Lukasek K, Michelsen KS, Arditi M. TLR signaling at the intestinal epithelial interface. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519030090050901] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The intestinal epithelium provides a critical interface between lumenal bacteria and the mucosal immune system. Whereas normal commensal flora do not trigger acute inflammation, pathogenic bacteria trigger a potent inflammatory response. Our studies emanate from the hypothesis that the intestinal epithelium is normally hyporesponsive to commensal pathogen-associated molecular patterns (PAMPs) such as LPS. Our data demonstrate that normal human colonic epithelial cells and lamina propria cells express low levels of TLR4 and its co-receptor MD-2. This expression pattern is mirrored by intestinal epithelial cell (IEC) lines. Co-expression of TLR4 and MD-2 is necessary and sufficient for LPS responsiveness in IEC. Moreover, LPS sensing occurs along the basolateral membrane of polarized IEC in culture. Expression of MD-2 is regulated by IFN-γ. Cloning of the MD-2 promoter demonstrates that promoter activity is increased by IFN-γ and blocked by the STAT inhibitor SOCS3. We conclude from our studies that the intestinal epithelium down-regulates expression of TLR4 and MD-2 and is LPS unresponsive. The Th1 cytokine IFN-γ up-regulates expression of MD-2 in a STAT-dependent fashion. The results of our studies have important implications for understanding human inflammatory bowel diseases.
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Affiliation(s)
- Maria T. Abreu
- Inflammatory Bowel Disease Center, Division of Gastroenterology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA,
| | - Lisa S. Thomas
- Inflammatory Bowel Disease Center, Division of Gastroenterology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Elizabeth T. Arnold
- Inflammatory Bowel Disease Center, Division of Gastroenterology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Katie Lukasek
- Inflammatory Bowel Disease Center, Division of Gastroenterology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Kathrin S. Michelsen
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Steven Spielberg Pediatric Research Center, Burns and Allen Research Institute
| | - Moshe Arditi
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Steven Spielberg Pediatric Research Center, Burns and Allen Research Institute
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Interleukin-8, CXCL1, and MicroRNA miR-146a Responses to Probiotic Escherichia coli Nissle 1917 and Enteropathogenic E. coli in Human Intestinal Epithelial T84 and Monocytic THP-1 Cells after Apical or Basolateral Infection. Infect Immun 2016; 84:2482-92. [PMID: 27297392 DOI: 10.1128/iai.00402-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/09/2016] [Indexed: 02/08/2023] Open
Abstract
Bacterium-host interactions in the gut proceed via directly contacted epithelial cells, the host's immune system, and a plethora of bacterial factors. Here we characterized and compared exemplary cytokine and microRNA (miRNA) responses of human epithelial and THP-1 cells toward the prototype enteropathogenic Escherichia coli (EPEC) strain E2348/69 (O127:H6) and the probiotic strain Escherichia coli Nissle 1917 (EcN) (O6:K5:H1). Human T84 and THP-1 cells were used as cell culture-based model systems for epithelial and monocytic cells. Polarized T84 monolayers were infected apically or basolaterally. Bacterial challenges from the basolateral side resulted in more pronounced cytokine and miRNA responses than those observed for apical side infections. Interestingly, the probiotic EcN also caused a pronounced transcriptional increase of proinflammatory CXCL1 and interleukin-8 (IL-8) levels when human T84 epithelial cells were infected from the basolateral side. miR-146a, which is known to regulate adaptor molecules in Toll-like receptor (TLR)/NF-κB signaling, was found to be differentially regulated in THP-1 cells between probiotic and pathogenic bacteria. To assess the roles of flagella and flagellin, we employed several flagellin mutants of EcN. EcN flagellin mutants induced reduced IL-8 as well as CXCL1 responses in T84 cells, suggesting that flagellin is an inducer of this cytokine response. Following infection with an EPEC type 3 secretion system (T3SS) mutant, we observed increased IL-8 and CXCL1 transcription in T84 and THP-1 cells compared to that in wild-type EPEC. This study emphasizes the differential induction of miR-146a by pathogenic and probiotic E. coli strains in epithelial and immune cells as well as a loss of probiotic properties in EcN interacting with cells from the basolateral side.
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Saka R, Wakimoto T, Nishiumi F, Sasaki T, Nose S, Fukuzawa M, Oue T, Yanagihara I, Okuyama H. Surfactant protein-D attenuates the lipopolysaccharide-induced inflammation in human intestinal cells overexpressing toll-like receptor 4. Pediatr Surg Int 2016; 32:59-63. [PMID: 26510735 DOI: 10.1007/s00383-015-3812-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/09/2015] [Indexed: 11/25/2022]
Abstract
PURPOSE Necrotizing enterocolitis (NEC) is a devastating inflammatory disease of preterm infants that may depend on overexpression of toll-like receptor-4 (TLR4) in the immature intestine. Surfactant protein (SP)-D is a member of the collectin family and plays an important role in innate immunity, particularly in the airways. Although SP-D also exists in the intestines, little is known about its function. This study investigated whether SP-D can attenuate the inflammatory response of TLR4-overexpressing embryonal intestinal cells. METHODS All experimental procedures were performed using the human intestinal cell line INT407 originally derived from human embryonal intestines. Platelet-activating factor (PAF), reported to be elevated in NEC patients, was used to induce TLR4 overexpression in the human embryonal intestinal cell line INT407. TLR4 expression was measured using quantitative real-time PCR. Inflammatory responses to PAF (5 µM), the TLR4 agonist lipopolysaccharide (LPS, 100 ng/ml), PAF + LPS, and PAF + LPS following SP-D pretreatment (20 µg/ml) were assessed by enzyme-linked immunosorbent assay (ELISA) of interleukin-8 (IL-8) release (in pg/ml). RESULTS Expression of TLR4 mRNA (mean ± SD) was upregulated by PAF (369 % ± 28 %, p < 0.001). Stimulation with PAF + LPS resulted in higher IL-8 release (1959.3 ± 52.3) than control (141.2 ± 12.4), LPS (167.3 ± 65.8), or PAF (1527.2 ± 129.4) treatment (p < 0.05). Release in response to PAF + LPS (1590.1 ± 319.3) was attenuated by SP-D pretreatment (1161.6 ± 131.6; p < 0.05). CONCLUSION SP-D attenuates LPS-induced IL-8 production in TLR4-overexpressing intestinal cells, suggesting that SP-D may have a protective effect in the development of NEC in preterm infants.
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Affiliation(s)
- Ryuta Saka
- Department of Pediatric Surgery, Hyogo College of Medicine, Nishinomiya, Japan.,Department of Pediatric Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, 5650871, Japan.,Department of Developmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan
| | - Tetsu Wakimoto
- Department of Developmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan.,Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Fumiko Nishiumi
- Department of Developmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan
| | - Takashi Sasaki
- Department of Pediatric Surgery, Hyogo College of Medicine, Nishinomiya, Japan
| | - Satoko Nose
- Department of Pediatric Surgery, Hyogo College of Medicine, Nishinomiya, Japan
| | - Masahiro Fukuzawa
- Department of Pediatric Surgery, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan
| | - Takaharu Oue
- Department of Pediatric Surgery, Hyogo College of Medicine, Nishinomiya, Japan
| | - Itaru Yanagihara
- Department of Developmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan
| | - Hiroomi Okuyama
- Department of Pediatric Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, 5650871, Japan.
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Powell DA, Roberts LM, Ledvina HE, Sempowski GD, Curtiss R, Frelinger JA. Distinct innate responses are induced by attenuated Salmonella enterica serovar Typhimurium mutants. Cell Immunol 2015; 299:42-9. [PMID: 26546408 DOI: 10.1016/j.cellimm.2015.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/09/2015] [Accepted: 10/13/2015] [Indexed: 02/04/2023]
Abstract
Upon bacterial infection the host cells generate a wide variety of cytokines. Genetic attenuation of bacterial physiological pathogens can be accomplished not only by disruption of normal bacterial processes, but also by the loss of the ability to redirect the host immune system. We examined nine attenuated Salmonella Typhimurium mutants for their ability to replicate as well as the cytokines produced after infection of Bone Marrow Derived Macrophages (BMDM). Infection of BMDM with attenuated Salmonella mutants led to host cytokine patterns distinct from those that followed WT infection. Surprisingly, each bacterial mutant had a unique cytokine signature. Because some of the mutants induced an IL-10 response not seen in WT, we examined the role of IL-10 on Salmonella replication. Surprisingly, addition of IL-10 before or concurrent with infection restricted growth of WT Salmonella in BMDM. Bacterial attenuation is not a single process and results in attenuated host responses, which result in unique patterns for each attenuated mutants.
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Affiliation(s)
- Daniel A Powell
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States.
| | - Lydia M Roberts
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States
| | - Hannah E Ledvina
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States
| | | | - Roy Curtiss
- Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, AZ 85281, United States
| | - Jeffrey A Frelinger
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States
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15
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Bacterial secretions of nonpathogenic Escherichia coli elicit inflammatory pathways: a closer investigation of interkingdom signaling. mBio 2015; 6:e00025. [PMID: 25759496 PMCID: PMC4453519 DOI: 10.1128/mbio.00025-15] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED There have been many studies on the relationship between nonpathogenic bacteria and human epithelial cells; however, the bidirectional effects of the secretomes (secreted substances in which there is no direct bacterium-cell contact) have yet to be fully investigated. In this study, we use a transwell model to explore the transcriptomic effects of bacterial secretions from two different nonpathogenic Escherichia coli strains on the human colonic cell line HCT-8 using next-generation transcriptome sequencing (RNA-Seq). E. coli BL21 and W3110, while genetically very similar (99.1% homology), exhibit key phenotypic differences, including differences in their production of macromolecular structures (e.g., flagella and lipopolysaccharide) and in their secretion of metabolic byproducts (e.g., acetate) and signaling molecules (e.g., quorum-sensing autoinducer 2 [AI-2]). After analysis of differential epithelial responses to the respective secretomes, this study shows for the first time that a nonpathogenic bacterial secretome activates the NF-κB-mediated cytokine-cytokine receptor pathways while also upregulating negative-feedback components, including the NOD-like signaling pathway. Because of AI-2's relevance as a bacterium-bacterium signaling molecule and the differences in its secretion rates between these strains, we investigated its role in HCT-8 cells. We found that the expression of the inflammatory cytokine interleukin 8 (IL-8) responded to AI-2 with a pattern of rapid upregulation before subsequent downregulation after 24 h. Collectively, these data demonstrate that secreted products from nonpathogenic bacteria stimulate the transcription of immune-related biological pathways, followed by the upregulation of negative-feedback elements that may serve to temper the inflammatory response. IMPORTANCE The symbiotic relationship between the microbiome and the host is important in the maintenance of human health. There is a growing need to further understand the nature of these relationships to aid in the development of homeostatic probiotics and also in the design of novel antimicrobial therapeutics. To our knowledge, this is the first global-transcriptome study of bacteria cocultured with human epithelial cells in a model to determine the transcriptional effects of epithelial cells in which epithelial and bacterial cells are allowed to "communicate" with each other only through diffusible small molecules and proteins. By beginning to demarcate the direct and indirect effects of bacteria on the gastrointestinal (GI) tract, two-way interkingdom communication can potentially be mediated between host and microbe.
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16
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Puig KL, Manocha GD, Combs CK. Amyloid precursor protein mediated changes in intestinal epithelial phenotype in vitro. PLoS One 2015; 10:e0119534. [PMID: 25742317 PMCID: PMC4351204 DOI: 10.1371/journal.pone.0119534] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/28/2015] [Indexed: 12/13/2022] Open
Abstract
Background Although APP and its proteolytic metabolites have been well examined in the central nervous system, there remains limited information of their functions outside of the brain. For example, amyloid precursor protein (APP) and amyloid beta (Aβ) immunoreactivity have both been demonstrated in intestinal epithelial cells. Based upon the critical role of these cells in absorption and secretion, we sought to determine whether APP or its metabolite amyloid β (Aβ), had a definable function in these cells. Methodology/Principal Findings The human colonic epithelial cell line, Caco-2 cells, were cultured to examine APP expression and Aβ secretion, uptake, and stimulation. Similar to human colonic epithelium stains, Caco-2 cells expressed APP. They also secreted Aβ 1-40 and Aβ 1-42, with LPS stimulating higher concentrations of Aβ 1-40 secretion. The cells also responded to Aβ 1-40 stimulation by increasing IL-6 cytokine secretion and decreasing cholesterol uptake. Conversely, stimulation with a sAPP-derived peptide increased cholesterol uptake. APP was associated with CD36 but not FATP4 in co-IP pull down experiments from the Caco-2 cells. Moreover, stimulation of APP with an agonist antibody acutely decreased CD36-mediated cholesterol uptake. Conclusions/Significance APP exists as part of a multi-protein complex with CD36 in human colonic epithelial cells where its proteolytic fragments have complex, reciprocal roles in regulating cholesterol uptake. A biologically active peptide fragment from the N-terminal derived, sAPP, potentiated cholesterol uptake while the β secretase generated product, Aβ1-40, attenuated it. These data suggest that APP is important in regulating intestinal cholesterol uptake in a fashion dependent upon specific proteolytic pathways. Moreover, this biology may be applicable to cells beyond the gastrointestinal tract.
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Affiliation(s)
- Kendra L. Puig
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Gunjan D. Manocha
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Colin K. Combs
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
- * E-mail:
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The Lactobacillus plantarum Eno A1 Enolase Is Involved in Immunostimulation of Caco-2 Cells and in Biofilm Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 897:33-44. [PMID: 26577529 DOI: 10.1007/5584_2015_5009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The role of probiotics in prevention and treatment of a variety of diseases is now well assessed. The presence of adhesive molecules on the cell surface of probiotics has been related to the ability to confer health benefit to the host. We have previously shown that the enolase EnoA1 of Lactobacillus plantarum, one of the most predominant species in the gut microbiota of healthy individuals, is cell surface-expressed and is involved in binding with human fibronectin and plasminogen. By means of comparative analysis between L. plantarum LM3 (wild type) and its isogenic LM3-CC1 (ΔenoA1) mutant strain, here we show that EnoA1 affects the ability of this bacterium to modulate immune response as determined by analysis of expression of immune system molecules in Caco-2 cells. Indeed, we observed induction of TLR2 expression in cells exposed to L. plantarum LM3, while no induction was detectable in cells exposed to LM3-CC1. This difference was much less consistent when expression of TLR4 was determined in cells exposed to the two strains. Pro-inflammatory (IL-6) and anti-inflammatory cytokines (IL-10, TGF-β), and the antimicrobial peptide HBD-2 were induced in Caco-2 cells exposed to L. plantarum LM3, while lower levels of induction were detected in cells exposed to LM3-CC1. We also analyzed the ability to develop biofilm of the two strains, and observed a decrease of about 65 % in the development of mature biofilm in LM3-CC1 compared to the wild type.
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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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McKim JM. Food additive carrageenan: Part I: A critical review of carrageenanin vitrostudies, potential pitfalls, and implications for human health and safety. Crit Rev Toxicol 2014; 44:211-43. [DOI: 10.3109/10408444.2013.861797] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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21
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Bein K, Di Giuseppe M, Mischler SE, Ortiz LA, Leikauf GD. LPS-treated macrophage cytokines repress surfactant protein-B in lung epithelial cells. Am J Respir Cell Mol Biol 2013; 49:306-15. [PMID: 23590297 PMCID: PMC3824031 DOI: 10.1165/rcmb.2012-0283oc] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 03/07/2013] [Indexed: 02/04/2023] Open
Abstract
In the mouse lung, Escherichia coli LPS can decrease surfactant protein-B (SFTPB) mRNA and protein concentrations. LPS also regulates the expression, synthesis, and concentrations of a variety of gene and metabolic products that inhibit SFTPB gene expression. The purpose of the present study was to determine whether LPS acts directly or indirectly on pulmonary epithelial cells to trigger signaling pathways that inhibit SFTPB expression, and whether the transcription factor CCAAT/enhancer binding protein (C/EBP)-β (CEBPB) is a downstream inhibitory effector. To investigate the mechanism of SFTPB repression, the human pulmonary epithelial cell lines NCI-H441 (H441) and NCI-H820 (H820) and the mouse macrophage-like cell line RAW264.7 were treated with LPS. Whereas LPS did not decrease SFTPB transcripts in H441 or H820 cells, the conditioned medium of LPS-treated RAW264.7 cells decreased SFTPB transcripts in H441 and H820 cells, and inhibited SFTPB promoter activity in H441 cells. In the presence of neutralizing anti-tumor necrosis factor (TNF) antibodies, the conditioned medium of LPS-treated RAW264.7 cells did not inhibit SFTPB promoter activity. In H441 cells treated with recombinant TNF protein, SFTPB transcripts decreased, whereas CEBPB transcripts increased and the transient coexpression of CEBPB decreased SFTPB promoter activity. Further, CEBPB short, interfering RNA increased basal SFTPB transcripts and countered the decrease of SFTPB transcripts by TNF. Together, these findings suggest that macrophages participate in the repression of SFTPB expression by LPS, and that macrophage-released cytokines (including TNF) regulate the transcription factor CEBPB, which can function as a downstream transcriptional repressor of SFTPB gene expression in pulmonary epithelial cells.
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Affiliation(s)
- Kiflai Bein
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219-3130, USA.
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22
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Osteopontin: participation in inflammation or mucosal protection in inflammatory bowel diseases? Dig Dis Sci 2013; 58:1569-80. [PMID: 23361573 DOI: 10.1007/s10620-012-2556-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Accepted: 12/24/2012] [Indexed: 12/22/2022]
Abstract
BACKGROUND Osteopontin (OPN) is associated with the Th1 immune response in inflammatory bowel diseases (IBD). While OPN has been shown to play an important role in maintaining the epithelial barrier, its role in IBD remains unclear. AIM The aim of this study was to assess OPN function in patients with IBD and in the mouse colitis model. METHODS Osteopontin expression in colonic samples from IBD patients was determined by a semi-quantitative immunohistochemical staining method. Colitis in BALB/c mice was induced by 5 % dextran sodium sulfate (DSS), followed by treatment with salazosulfapyridine (SASP) and infliximab, respectively. The plasma OPN concentration was measured by an enzyme-linked immunosorbent assay. The expression of OPN in colonic tissues was detected by reverse transcriptase PCR, real-time PCR and Western blot, and the localization of OPN was determined by a semi-quantitative immunohistochemical staining method. The immune function of OPN was investigated by measuring the production of cytokines, and the amount of cytokines produced was then used to determine OPN immune functions. RESULTS Osteopontin expression in intestinal epithelial cells was significantly lower in IBD patients than in controls, while its expression in lamina propria exudative cells was significantly higher in IBD patients than in controls. In DSS-induced mice, OPN expression in plasma and colonic tissues increased significantly, and this increase was significantly reduced after the mice were treated with SASP and infliximab. OPN promoted the Th1 immune response and strengthened inflammation in the mouse colitis model. CONCLUSIONS Our results indicate that OPN plays an important role in the immune response and is also involved in the mucosal protective mechanism in IBD.
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Yasuda M, Furuyashiki T, Nakamura T, Kakutani R, Takata H, Ashida H. Immunomodulatory activity of enzymatically synthesized glycogen and its digested metabolite in a co-culture system consisting of differentiated Caco-2 cells and RAW264.7 macrophages. Food Funct 2013; 4:1387-93. [DOI: 10.1039/c3fo60035a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Duerr CU, Hornef MW. The mammalian intestinal epithelium as integral player in the establishment and maintenance of host-microbial homeostasis. Semin Immunol 2011; 24:25-35. [PMID: 22138188 DOI: 10.1016/j.smim.2011.11.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Only one single layer of epithelial cells separates the densely colonized and environmentally exposed intestinal lumen from the largely sterile subepithelial tissue. Together with the overlaying mucus and the subepithelial mucosal immune system the epithelium has evolved to maintain homeostasis in the presence of the enteric microbiota. It also contributes to rapid and efficient antimicrobial host defence in the event of infection with pathogenic microorganisms. Both, epithelial antimicrobial host defence and homeostasis rely on signalling pathways induced by innate immune receptors demonstrating the active role of epithelial cells in the host-microbial interplay. The interaction of epithelial cells with professional immune cells illustrates the integrated function within the mucosal tissue. In the present review we focus on structural and functional changes of the intestinal epithelium during the fetal-neonatal transition and infancy and try to delineate its role in the induction and maintenance of host-microbial homeostasis. We also address factors that impair epithelial functions and may lead to disruption of the mucosal barrier, tissue damage and the development of symptomatic disease.
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Affiliation(s)
- Claudia U Duerr
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Carl-Neuberg Str. 1, D-30625 Hannover, Germany
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25
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Probiotic therapy: immunomodulating approach toward urinary tract infection. Curr Microbiol 2011; 63:484-90. [PMID: 21901556 DOI: 10.1007/s00284-011-0006-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 08/19/2011] [Indexed: 01/25/2023]
Abstract
Urinary tract infection (UTI) is an extremely common health problem, with an unpredictable history. Members of enterobacteriaceae family such as Escherichia coli, which are normal inhabitants of human intestines, account for the majority of these uncomplicated infections. Rarely, UTI can result from virus or fungus. There is a close correlation between loss of the normal genital microbiota, particularly Lactobacillus species, and an increased incidence of genital and bladder infections. Although antimicrobial agents are generally effective in eradicating these infections, there is a high incidence of recurrence. Use of Lactobacillus species to combat UTI is now giving modern concept of modern genitourinary vaccine with the facts that it not only maintains low pH of the genital area, produces hydrogen peroxide and hinders the growth of E. coli but also activates Toll-like receptor-2 (TLR2), which produces interleukin-10 (IL-10) and myeloid differentiation factor 88 (MyD88). E. coli activates TLR4, which is responsible for the activation of IL-12, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). This process downregulates inflammatory reactions caused due to pathogens. Current review covers the probiotics-based TLR therapy and shed some knowledge for the use of Lactobacillus species as probiotics.
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Fraser-Pitt DJ, Cameron P, McNeilly TN, Boyd A, Manson EDT, Smith DGE. Phosphorylation of the epidermal growth factor receptor (EGFR) is essential for interleukin-8 release from intestinal epithelial cells in response to challenge with Escherichia coli O157 : H7 flagellin. MICROBIOLOGY-SGM 2011; 157:2339-2347. [PMID: 21546588 DOI: 10.1099/mic.0.047670-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Enterohaemorrhagic Escherichia coli O157 : H7 is a major foodborne and environmental pathogen responsible for both sporadic cases and outbreaks of food poisoning, which can lead to serious sequelae, such as haemolytic uraemic syndrome. The structural subunit of E. coli O157 : H7 flagella is flagellin, which is both the antigenic determinant of the H7 serotype, an important factor in colonization, and an immunomodulatory protein that has been determined to be a major pro-inflammatory component through the instigation of host cell signalling pathways. Flagellin has highly conserved N- and C-terminal regions that are recognized by the host cell pattern recognition receptor Toll-like receptor (TLR) 5. Activation of this receptor triggers cell signalling cascades, which are known to activate host cell kinases and transcription factors that respond with the production of inflammatory mediators such as the chemokine interleukin-8 (IL-8), although the exact components of this pathway are not yet fully characterized. We demonstrate that E. coli O157 : H7-derived flagellin induces rapid phosphorylation of the epidermal growth factor receptor (EGFR), as an early event in intestinal epithelial cell signalling, and that this is required for the release of the pro-inflammatory cytokine IL-8.
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Affiliation(s)
- Douglas J Fraser-Pitt
- Biomedical Sciences and Microbiology Group, School of Life, Sport and Social Sciences, Faculty of Health, Life and Social Sciences, Sighthill Campus, Edinburgh Napier University, Edinburgh EH11 4BN, UK
| | - Pamela Cameron
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Tom N McNeilly
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Amanda Boyd
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Erin D T Manson
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - David G E Smith
- Institute for Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Glasgow G61 1QH, UK.,Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
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Pudney J, Anderson DJ. Expression of toll-like receptors in genital tract tissues from normal and HIV-infected men. Am J Reprod Immunol 2011; 65:28-43. [PMID: 20528831 DOI: 10.1111/j.1600-0897.2010.00877.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
PROBLEM cells of the innate immune system use Toll-like receptors (TLRs) to recognize and respond to invading pathogens. This study was carried out to characterize TLR expression in the human male genital tract, an initial infection site for several sexually transmitted pathogens. METHOD OF STUDY immunohistochemistry was used to detect expression of TLRs 1-9 in genital tract tissues from HIV(-) and HIV(+) men. RESULTS in HIV(-) men, TLR1(+) leukocytes were detected throughout the genital tract. Leukocytes in the penile urethra also expressed TLRs2, 3, 5, 7 and 9. Epithelial cells in most tissues did not express TLRs; exceptions were the prostate, where TLRs3 and 8 were observed on the apical surface of luminal epithelial cells, and the penile urethra, where epithelial cells expressed TLR9. In genital tissues from HIV(+) men with AIDS, few TLR(+) cells were detected. CONCLUSION cells in the male genital tract can express a variety of TLRs. The penile urethra contained the highest number of TLR(+) cells, indicating that this tissue plays a major role in the innate immune defense of the male genital tract. Overall, TLR expression was reduced in genital tissues from HIV(+) men.
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Affiliation(s)
- Jeffrey Pudney
- Department of Obstetrics/Gynecology, Boston University School of Medicine, Boston, MA 02118, USA.
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Soliman A, Michelsen KS, Karahashi H, Lu J, Meng FJ, Qu X, Crother TR, Rabizadeh S, Chen S, Caplan MS, Arditi M, Jilling T. Platelet-activating factor induces TLR4 expression in intestinal epithelial cells: implication for the pathogenesis of necrotizing enterocolitis. PLoS One 2010; 5:e15044. [PMID: 20976181 PMCID: PMC2955554 DOI: 10.1371/journal.pone.0015044] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 08/16/2010] [Indexed: 12/30/2022] Open
Abstract
Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in neonatal intensive care units, however its pathogenesis is not completely understood. We have previously shown that platelet activating factor (PAF), bacteria and TLR4 are all important factors in the development of NEC. Given that Toll-like receptors (TLRs) are expressed at low levels in enterocytes of the mature gastrointestinal tract, but were shown to be aberrantly over-expressed in enterocytes in experimental NEC, we examined the regulation of TLR4 expression and signaling by PAF in intestinal epithelial cells using human and mouse in vitro cell lines, and the ex vivo rat intestinal loop model. In intestinal epithelial cell (IEC) lines, PAF stimulation yielded upregulation of both TLR4 mRNA and protein expression and led to increased IL-8 secretion following stimulation with LPS (in an otherwise LPS minimally responsive cell line). PAF stimulation resulted in increased human TLR4 promoter activation in a dose dependent manner. Western blotting and immunohistochemical analysis showed PAF induced STAT3 phosphorylation and nuclear translocation in IEC, and PAF-induced TLR4 expression was inhibited by STAT3 and NFκB Inhibitors. Our findings provide evidence for a mechanism by which PAF augments inflammation in the intestinal epithelium through abnormal TLR4 upregulation, thereby contributing to the intestinal injury of NEC.
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Affiliation(s)
- Antoine Soliman
- Department of Pediatrics, University of California Los Angeles School of Medicine, Los Angeles, California, United States of America
| | - Kathrin S. Michelsen
- Department of Pediatrics, University of California Los Angeles School of Medicine, Los Angeles, California, United States of America
| | - Hisae Karahashi
- Department of Pediatrics, University of California Los Angeles School of Medicine, Los Angeles, California, United States of America
| | - Jing Lu
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Evanston Northwestern Healthcare Research Institute, Evanston, Illinois, United States of America
| | - Fan Jing Meng
- Evanston Northwestern Healthcare Research Institute, Evanston, Illinois, United States of America
| | - Xiaowu Qu
- Evanston Northwestern Healthcare Research Institute, Evanston, Illinois, United States of America
| | - Timothy R. Crother
- Department of Pediatrics, University of California Los Angeles School of Medicine, Los Angeles, California, United States of America
| | - Shervin Rabizadeh
- Department of Pediatrics, University of California Los Angeles School of Medicine, Los Angeles, California, United States of America
| | - Shuang Chen
- Department of Pediatrics, University of California Los Angeles School of Medicine, Los Angeles, California, United States of America
| | - Michael S. Caplan
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Evanston Northwestern Healthcare Research Institute, Evanston, Illinois, United States of America
| | - Moshe Arditi
- Department of Pediatrics, University of California Los Angeles School of Medicine, Los Angeles, California, United States of America
| | - Tamas Jilling
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Evanston Northwestern Healthcare Research Institute, Evanston, Illinois, United States of America
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Human airway epithelial cell responses to Neisseria lactamica and purified porin via Toll-like receptor 2-dependent signaling. Infect Immun 2010; 78:5314-23. [PMID: 20937766 DOI: 10.1128/iai.00681-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The human airway epithelium is constantly exposed to microbial products from colonizing organisms. Regulation of Toll-like receptor (TLR) expression and specific interactions with bacterial ligands is thought to mitigate exacerbation of inflammatory processes induced by the commensal flora in these cells. The genus Neisseria comprises pathogenic and commensal organisms that colonize the human nasopharynx. Neisseria lactamica is not associated with disease, but N. meningitidis occasionally invades the host, causing meningococcal disease and septicemia. Upon colonization of the airway epithelium, specific host cell receptors interact with numerous Neisseria components, including the PorB porin, at the immediate bacterial-host cell interface. This major outer membrane protein is expressed by all Neisseria strains, regardless of pathogenicity, but its amino acid sequence varies among strains, particularly in the surface-exposed regions. The interaction of Neisseria PorB with TLR2 is essential for driving TLR2/TLR1-dependent cellular responses and is thought to occur via the porin's surface-exposed loop regions. Our studies show that N. lactamica PorB is a TLR2 ligand but its binding specificity for TLR2 is different from that of meningococcal PorB. Furthermore, N. lactamica PorB is a poor inducer of proinflammatory mediators and of TLR2 expression in human airway epithelial cells. These effects are reproduced by whole N. lactamica organisms. Since the responsiveness of human airway epithelial cells to colonizing bacteria is in part regulated via TLR2 expression and signaling, commensal organisms such as N. lactamica would benefit from expressing a product that induces low TLR2-dependent local inflammation, likely delaying or avoiding clearance by the host.
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Toll-like receptor 4 is protective against neonatal murine ischemia-reperfusion intestinal injury. J Pediatr Surg 2010; 45:1246-55. [PMID: 20620328 PMCID: PMC2952414 DOI: 10.1016/j.jpedsurg.2010.02.093] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Accepted: 02/23/2010] [Indexed: 12/16/2022]
Abstract
PURPOSE Premature infants receiving probiotics have a decreased incidence of necrotizing enterocolitis. This may be mediated by intestinal bacterial signaling via toll-like receptors (TLRs) 2 and 4 maintaining intestinal homeostasis. We hypothesized that TLRs 2 and 4 are protective against ischemia-reperfusion (I/R) intestinal injury. METHODS Two-week-old C57BL/6 wild-type (WT), B6.TLR2(-/-), B6.TLR4(-/-), B6.TLR2(-/-)4(-/-), and microbially reduced (antibiotic-treated) mice (MR) underwent 60 minutes of superior mesenteric artery occlusion (I) followed by 90 minutes of reperfusion (R). Small intestine was harvested for analysis of microscopic injury, apoptosis, and inflammatory gene expression using quantitative polymerase chain reaction. RESULTS After I/R, the median histologic injury scores of the B6.TLR4(-/-), B6.TLR2(-/-)4(-/-), and MR pups were higher than the WT or B6.TLR2(-/-) pups that corresponded with greater apoptosis based on terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick-end labeling and activated caspase-3 immunostaining. B6.TLR4(-/-), B6.TLR2(-/-)4(-/-), and MR also had elevated tissue innate immunity-associated chemokine and cytokine expression. CONCLUSIONS Neonatal mice deficient in TLR4, either alone or also deficient in TLR2, as well as those lacking a normal commensal intestinal microbiome are more susceptible to an I/R model of intestinal injury. These results may provide a mechanism for commensal bacterial-mediated protection, which may help to direct further studies to elucidate the mechanism of probiotic protection.
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Toll-like receptor signalling in the intestinal epithelium: how bacterial recognition shapes intestinal function. Nat Rev Immunol 2010; 10:131-44. [PMID: 20098461 DOI: 10.1038/nri2707] [Citation(s) in RCA: 874] [Impact Index Per Article: 62.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A single layer of epithelial cells lines the small and large intestines and functions as a barrier between commensal bacteria and the rest of the body. Ligation of Toll-like receptors (TLRs) on intestinal epithelial cells by bacterial products promotes epithelial cell proliferation, secretion of IgA into the gut lumen and expression of antimicrobial peptides. As described in this Review, this establishes a microorganism-induced programme of epithelial cell homeostasis and repair in the intestine. Dysregulation of this process can result in chronic inflammatory and over-exuberant repair responses, and it is associated with the development of colon cancer. Thus, dysregulated TLR signalling by intestinal epithelial cells may explain how colonic bacteria and inflammation promote colorectal cancer.
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Innate and acquired immune responses induced by recombinant Lactobacillus casei displaying flagellin-fusion antigen on the cell-surface. Vaccine 2010; 28:3409-15. [PMID: 20197143 DOI: 10.1016/j.vaccine.2010.02.077] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2009] [Revised: 02/05/2010] [Accepted: 02/15/2010] [Indexed: 02/05/2023]
Abstract
Bacterial flagellins are known as antigens that induce innate immune responses through TLR5 and boost immune responses in combination with other antigens. The aim of the present study was to determine the immunological properties of recombinant Lactobacillus casei producing flagellin and flagellin-fusion antigens in vitro and in vivo. Recombinant lactobacilli expressing Salmonella FliC and FliC fused to truncated SipC on the cell-surface were constructed. Fusion and non-fusion flagellin associated with L. casei retained the ability to induce IL-8 production by Caco-2 cells. Immunization of mice with these recombinant strains induced antigen-specific antibodies and cytokine production. The results showed that the outside epitope of the heterologous antigen was recognized more easily by the immune system than the inside epitope. The immune responses elicited by the Lactobacillus-associated antigens were mainly Th1 while that by the soluble antigen was Th2, although some of the responses were mixed.
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Gao N, Kumar A, Jyot J, Yu FS. Flagellin-induced corneal antimicrobial peptide production and wound repair involve a novel NF-kappaB-independent and EGFR-dependent pathway. PLoS One 2010; 5:e9351. [PMID: 20195469 PMCID: PMC2829077 DOI: 10.1371/journal.pone.0009351] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Accepted: 01/29/2010] [Indexed: 01/17/2023] Open
Abstract
Background The bacterial protein flagellin plays a major role in stimulating mucosal surface innate immune response to bacterial infection and uniquely induces profound cytoprotection against pathogens, chemicals, and radiation. This study sought to determine signaling pathways responsible for the flagellin-induced inflammatory and cytoprotective effects on human corneal epithelial cells (HCECs). Methodology/Principal Findings Flagellin purified from Pseudomonas aeruginosa (strain PAK) or live bacteria were used to challenge cultured HCECs. The activation of signaling pathways was assessed with Western blot, and the secretion of cytokine/chemokine and production of antimicrobial peptides (AMPs) were measured with ELISA and dot blot, respectively. Effects of flagellin on wound healing were assessed in cultured porcine corneas. L94A (a site mutation in TLR5 binding region) flagellin and PAK expressing L94A flagellin were unable to stimulate NF-κB activation, but were potent in eliciting EGFR signaling in a TGF-α–related pathway in HCECs. Concomitant with the lack of NF-κB activation, L94A flagellin was ineffective in inducing IL-6 and IL-8 production in HCECs. Surprisingly, the secretion of two inducible AMPs, LL-37 and hBD2, was not affected by L94A mutation. Similar to wild-type flagellin, L94A induced epithelial wound closure in cultured porcine cornea through maintaining EGFR-mediated signaling. Conclusions/Significance Our data suggest that inflammatory response mediated by NF-κB can be uncoupled from epithelial innate defense machinery (i.e., AMP expression) and major epithelial proliferation/repair pathways mediated by EGFR, and that flagellin and its derivatives may have broad therapeutic applications in cytoprotection and in controlling infection in the cornea and other mucosal tissues.
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Affiliation(s)
- Nan Gao
- Departments of Ophthalmology, Anatomy, and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ashok Kumar
- Departments of Ophthalmology, Anatomy, and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Jeevan Jyot
- Department of Medicine/Infectious Diseases, University of Florida, Gainesville, Florida, United States of America
| | - Fu-Shin Yu
- Departments of Ophthalmology, Anatomy, and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- * E-mail:
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Yasuda Y, Matsumura Y, Kasahara K, Ouji N, Sugiura S, Mikasa K, Kita E. Microbial exposure early in life regulates airway inflammation in mice after infection with Streptococcus pneumoniae with enhancement of local resistance. Am J Physiol Lung Cell Mol Physiol 2010; 298:L67-78. [DOI: 10.1152/ajplung.00193.2009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The immunological explanation for the “hygiene hypothesis” has been proposed to be induction of T helper 1 (Th1) responses by microbial products. However, the protective results of hygiene hypothesis-linked microbial exposures are currently shown to be unlikely to result from a Th1-skewed response. Until now, effect of microbial exposure early in life on airway innate resistance remained unclear. We examined the role of early life exposure to microbes in airway innate resistance to a respiratory pathogen. Specific pathogen-free weanling mice were nasally exposed to the mixture of microbial extracts or PBS (control) every other day for 28 days and intratracheally infected with Streptococcus pneumoniae 10 days after the last exposure. Exposure to microbial extracts facilitated colonization of aerobic gram-positive bacteria, anaerobic microorganisms, and Lactobacillus in the airway, compared with control exposure. In pneumococcal pneumonia, the exposure prolonged mouse survival days by suppressing bacterial growth and by retarding pneumococcal blood invasion, despite significantly low levels of leukocyte recruitment in the lung. Enhancement of airway resistance was associated with a significant decrease in production of leukocyte chemokine (KC) and TNFα, and suppression of matrix metalloproteinase (MMP-9) expression/activation with enhancement of tissue inhibitor of MMP (TIMP-3) activation. The exposure increased production of IFN-γ, IL-4, and monocyte chemoattractant-1 following infection. Furthermore, expression of Toll-like receptor 2, 4, and 9 was promoted by the exposure but no longer upregulated upon pneumococcal infection. Thus, we suggest that hygiene hypothesis is more important in regulating the PMN-dominant inflammatory response than in inducing a Th1-dominant response.
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Affiliation(s)
| | | | | | | | | | - Keiichi Mikasa
- Center for Infectious Diseases, Nara Medical University, School of Medicine, Kashihara, Nara, Japan
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Abstract
Soon after birth, the neonatal intestine is confronted with a massive antigenic challenge of microbial colonization. Microbial signals are required for maturation of several physiological, anatomical, and biochemical functions of intestinal epithelial barrier (IEB) after birth. Commensal bacteria regulate intestinal innate and adaptive immunity and provide stimuli for ongoing repair and restitution of IEB. Colonization by pathogenic bacteria and/or dysmature response to microbial stimuli can result in flagrant inflammatory response as seen in necrotizing enterocolitis (NEC). Characterized by inflammation and hemorrhagic-ischemic necrosis, NEC is a devastating complication of prematurity. Although there is evidence that both prematurity and presence of bacteria, are proven contributing factors to the pathogenesis of NEC, the molecular mechanisms involved in IEB dysfunction associated with NEC have begun to emerge only recently. The metagenomic advances in the field of intestinal microecology are providing insight into the factors that are required for establishment of commensal bacteria that appear to provide protection against intestinal inflammation and NEC. Perturbations in achieving colonization by commensal bacteria such as premature birth or hospitalization in intensive care nursery can result in dysfunction of IEB and NEC. In this article, microbial modulation of functions of IEB and its relationship with barrier dysfunction and NEC are described.
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Affiliation(s)
- Renu Sharma
- Division of Neonatology, Department of Pediatrics, University of Florida at Jacksonville, 655 West 8th Street, Jacksonville, FL 32209, USA.
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Fukata M, Abreu MT. Pathogen recognition receptors, cancer and inflammation in the gut. Curr Opin Pharmacol 2009; 9:680-7. [PMID: 19828376 PMCID: PMC2826797 DOI: 10.1016/j.coph.2009.09.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 09/14/2009] [Accepted: 09/17/2009] [Indexed: 12/31/2022]
Abstract
The pathogen recognition receptors (PRRs) initiate immediate responses against infection and tissue damage to protect the host from microbial invasion. In response to mucosal damage, intestinal PRR signaling initiates damage repair processes. Recent advances appear to link PRR abnormalities and inflammatory as well as neoplastic intestinal disorders. Emerging evidence suggests a dual role of PRRs, in which they may simultaneously induce tumorigenesis and antitumor immunity. PRR may induce tumor cell proliferation by activating cell survival signaling mainly via NF-kappaB, but this signal can activate dendritic cells to promote antitumor immunity. TLR signaling within the tumor cells may result in evasion of immune surveillance, propagation of metastatic growth, or rather, induction of tumor cell apoptosis depending on ligands. Epithelial cells induce endogenous PRR ligands when damaged or during neoplastic transformation. Targeted manipulation of PRR signaling may provide emerging opportunities for the development of new therapeutic strategies for many gastrointestinal diseases.
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Affiliation(s)
- Masayuki Fukata
- Division of Gastroenterology, Department of Medicine, University of Miami Miller School of Medicine, Locator Code D-149, 1011 NW 15th St, Miami, FL 33136, USA.
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Cashman SB, Morgan JG. Transcriptional analysis of Toll-like receptors expression in M cells. Mol Immunol 2009; 47:365-72. [PMID: 19781788 DOI: 10.1016/j.molimm.2009.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 09/03/2009] [Indexed: 02/06/2023]
Abstract
M cells are located in the follicle associated epithelium (FAE) of Peyer's patches (PPs) in the small intestine, where they mediate the uptake and transcytosis of luminal antigens to the underlying lymphoid tissue. Toll-like receptors (TLRs) have emerged as key mediators in the innate immune response by recognising pathogen associated molecular patterns (PAMPs) expressed by microorganisms. TLRs have previously been shown to be differentially expressed in the gastrointestinal tract. In this study PP were harvested from BALB/c mice. Ulex europaeus agglutinin 1 (UAE-1) positive M cells were isolated from FAE and the expression of TLR1-9 transcripts in M cells, FAE and villus epithelium (VE) was compared by quantitative real-time PCR. Transcripts for TLR1, TLR2 and TLR4 were found to be expressed at a high level in M cells in comparison to VE, with no transcripts being detected in the FAE. TLR3 and TLR6 were not found to be expressed in M cells or in the FAE. TLR5 and TLR7 were found to be expressed at a higher level in FAE compared to M cells. TLR9, which recognises unmethylated CpG DNA of bacteria and viruses and TLR8, which recognises ssRNA, were found to be preferentially expressed in M cells compared to FAE and VE.
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Cerovic V, McDonald V, Nassar MA, Paulin SM, Macpherson GG, Milling SWF. New insights into the roles of dendritic cells in intestinal immunity and tolerance. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 272:33-105. [PMID: 19121816 DOI: 10.1016/s1937-6448(08)01602-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Dendritic cells (DCs) play a critical key role in the initiation of immune responses to pathogens. Paradoxically, they also prevent potentially damaging immune responses being directed against the multitude of harmless antigens, to which the body is exposed daily. These roles are particularly important in the intestine, where only a single layer of epithelial cells provides a barrier against billions of commensal microorganisms, pathogens, and food antigens, over a huge surface area. In the intestine, therefore, DCs are required to perform their dual roles very efficiently to protect the body from the dual threats of invading pathogens and unwanted inflammatory reactions. In this review, we first describe the biology of DCs and their interactions with other cells types, paying particular attention to intestinal DCs. We, then, examine the ways in which this biology may become misdirected, resulting in inflammatory bowel disease. Finally, we discuss how DCs potentiate immune responses against viral, bacterial, parasitic infections, and their importance in the pathogenesis of prion diseases. We, therefore, provide an overview of the complex cellular interactions that affect intestinal DCs and control the balance between immunity and tolerance.
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Affiliation(s)
- Vuk Cerovic
- Sir William Dunn School of Pathology, Oxford University, Oxford, United Kingdom
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Abstract
Crohn disease and ulcerative colitis are chronic inflammatory diseases of the intestinal tract commonly denoted as inflammatory bowel diseases. It has been proposed that these diseases result from aberrant mucosal immune responses to nonpathogenic microbial residents of the intestines. Recently, it was established that continuous interactions between the innate and the adaptive intestinal immune cells and the microbiota are directly involved in maintaining the physiological noninflammatory state of the intestinal mucosa. In light of the complexity of this mucosal homeostasis, it is astonishing that the inflammatory bowel diseases are relatively rare. Recently, altered functions of the innate immune system have been identified. As such, both hyperresponsiveness and hyporesponsiveness of innate cells have been implicated in the pathogenesis of inflammatory bowel diseases.
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Gribar SC, Richardson WM, Sodhi CP, Hackam DJ. No longer an innocent bystander: epithelial toll-like receptor signaling in the development of mucosal inflammation. Mol Med 2008; 14:645-59. [PMID: 18584047 PMCID: PMC2435494 DOI: 10.2119/2008-00035.gribar] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Accepted: 06/14/2008] [Indexed: 12/17/2022] Open
Abstract
Diseases of mucosal inflammation represent important causes of morbidity and mortality, and have led to intense research efforts to understand the factors that lead to their development. It is well accepted that a breakdown of the normally impermeant epithelial barrier of the intestine, the lung, and the kidney is associated with the development of inflammatory disease in these organs, yet significant controversy exists as to how this breakdown actually occurs, and how such a breakdown may lead to inflammation. In this regard, much work has focused upon the role of the epithelium as an “innocent bystander,” a target of a leukocyte-mediated inflammatory cascade that leads to its destruction in the mucosal inflammatory process. However, recent evidence from a variety of laboratories indicates that the epithelium is not merely a passive component in the steps that lead to mucosal inflammation, but is a central participant in the process. In addressing this controversy, we and others have determined that epithelial cells express Toll-like receptors (TLRs) of the innate immune system, and that activation of TLRs by endogenous and exogenous ligands may play a central role in determining the balance between a state of “mucosal homeostasis,” as is required for optimal organ function, and “mucosal injury,” leading to mucosal inflammation and barrier breakdown. In particular, activation of TLRs within intestinal epithelial cells leads to the development of cellular injury and impairment in mucosal repair in the pathogenesis of intestinal inflammation, while activation of TLRs in the lung and kidney may participate in the development of pneumonitis and nephritis respectively. Recent work in support of these concepts is extensively reviewed, while essential areas of further study that are required to determine the significance of epithelial TLR signaling during states of health and disease are outlined.
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Affiliation(s)
- Steven C Gribar
- Division of Pediatric Surgery, Department of Surgery, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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Lack of MD-2 expression in human corneal epithelial cells is an underlying mechanism of lipopolysaccharide (LPS) unresponsiveness. Immunol Cell Biol 2008; 87:141-8. [PMID: 18936773 PMCID: PMC2645480 DOI: 10.1038/icb.2008.75] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In the present study we tested the responsiveness of human corneal epithelial cells (HCECs) and corneal fibroblasts to lipopolysaccharide (LPS), a TLR4 ligand. Purified P aeruginosa LPS was used to stimulate telomerase-immortalized HCECs (HUCL) and stromal fibroblast (THK) cell lines. Exposure of cells to LPS induced a time-dependent activation of NF-κB in THK but not in HUCL cells, as assessed by an increase in IκB-α phosphorylation and degradation. Concomitant with NF-κB activation, LPS-treated THK cells, but not HUCL cells, produced significantly more cytokines than control untreated cells. A cell surface biotinylation assay revealed that HUCL cells express TLR4 intracellularly whereas TLR5 is expressed on the cell surface. Furthermore, RT-PCR analysis revealed that HUCL and primary HCECs, in contrast to THK cells, do not express MD-2. Thus, our results demonstrate that the LPS unresponsiveness of HCECs might be due to deficient expression of MD2, an essential component for LPS-TLR4 signaling.
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Bhattacharyya S, Gill R, Chen ML, Zhang F, Linhardt RJ, Dudeja PK, Tobacman JK. Toll-like receptor 4 mediates induction of the Bcl10-NFkappaB-interleukin-8 inflammatory pathway by carrageenan in human intestinal epithelial cells. J Biol Chem 2008; 283:10550-8. [PMID: 18252714 PMCID: PMC2447641 DOI: 10.1074/jbc.m708833200] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 01/28/2008] [Indexed: 12/28/2022] Open
Abstract
The sulfated polysaccharide carrageenan (CGN) induces activation of NFkappaB and interleukin 8 (IL-8) in human colonic epithelial cells through a pathway of innate immunity mediated by Bcl10 (B-cell CLL/lymphoma 10). In this report, we identify Toll-like receptor 4 (TLR4), a member of the family of innate immune receptors, as the surface membrane receptor for CGN in human colonic epithelial cells. Experiments with fluorescence-tagged CGN demonstrated a marked reduction in binding of CGN to human intestinal epithelial cells and to RAW 264.7 mouse macrophages, following exposure to TLR4 blocking antibody (HTA-125). Binding of CGN to 10ScNCr/23 mouse macrophages, which are deficient in the genetic locus for TLR4, was absent. Additional experiments with TLR4 blocking antibody and TLR4 small interfering RNAs showed 80% reductions in CGN-induced increases in Bcl10 and IL-8. Transfection with dominant-negative MyD88 plasmid demonstrated MyD88 dependence of the CGN-TLR4-triggered increases in Bcl10 and IL-8. Therefore, these results indicate that CGN-induced inflammation in human colonocytes proceeds through a pathway of innate immunity, perhaps related to the unusual alpha-1,3-galactosidic linkage characteristic of CGN, and suggest how dietary CGN intake may contribute to human intestinal inflammation. Because CGN is a commonly used food additive in the Western diet, clarification of its effects and mechanisms of action are vital to issues of food safety.
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Affiliation(s)
- Sumit Bhattacharyya
- Department of Medicine, University of Illinois, Chicago, Illinois 60612, USA
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Frost BL, Jilling T, Caplan MS. The importance of pro-inflammatory signaling in neonatal necrotizing enterocolitis. Semin Perinatol 2008; 32:100-6. [PMID: 18346533 PMCID: PMC2362144 DOI: 10.1053/j.semperi.2008.01.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Despite modern medical advances, necrotizing enterocolitis (NEC) remains a significant cause of morbidity and mortality in neonatal intensive care units, affecting 10% of premature neonates born weighing less than 1500 g. Although many advances have been made in the understanding of NEC, the etiology and pathophysiology remain incompletely understood, and treatment is limited to supportive care. In recent years, many studies have evaluated the inflammatory cascade that is central to the disease process, and research is ongoing into strategies to prevent and/or ameliorate neonatal NEC. In this review, we examine the key points in the signaling pathways involved in NEC, and potential strategies for prevention and treatment of this dreaded disease.
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Abstract
Mounting evidence supports the tenet that innate immune responses to luminal microbes participate in the development of gastrointestinal malignancies. The gastrointestinal tract is relatively unique in that it has evolved in the presence of diverse enteric microflora. Intestinal flora is required to develop a normal adaptive immune response in the periphery. With the characterization of the innate immune system, we have begun to understand the adaptations the intestine has made to the microbiota. The interaction between the microbiota and the intestinal mucosa through Toll-like receptors (TLRs) is required to maintain intestinal homeostasis. In particular, intestinal epithelial cells and lamina propria mononuclear cells such as antigen-presenting cells and T cells must respond to breaches in the mucosal barrier by activating TLR-dependent pathways that result in increased epithelial proliferation, wound healing and recruitment of acute inflammatory cells. In the setting of chronic inflammation such as Helicobacter pylori (H. pylori) infection in the stomach or idiopathic inflammatory bowel disease, the process of repair may eventually result in carcinogenesis. The following review highlights human and animal data that support a role for innate immune responses and TLRs specifically in promoting gastrointestinal malignancies. Candidate pathways linking TLRs to gastrointestinal malignancies include activation of nuclear factor-kappaB and cyclooxygenase-2. Studying the link between innate immune signaling and gastrointestinal malignancies offers the possibility to identify novel ways to both prevent and treat gastrointestinal cancer.
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Affiliation(s)
- M Fukata
- Inflammatory Bowel Disease Center, Division of Gastroenterology, Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
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Gribar SC, Anand RJ, Sodhi CP, Hackam DJ. The role of epithelial Toll-like receptor signaling in the pathogenesis of intestinal inflammation. J Leukoc Biol 2007; 83:493-8. [PMID: 18160540 DOI: 10.1189/jlb.0607358] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Emerging evidence suggests that the innate immune system, comprised of Toll-like receptors (TLRs) and their associated molecules, plays a pivotal role in the regulation of intestinal inflammation and in the response to invading pathogens. Although TLRs are thought to have predominantly beneficial effects in pathogen recognition and bacterial clearance by leukocytes, their dysregulation and unique signaling effects within intestinal epithelia in the setting of inflammation may have devastating consequences. For instance, activation of TLR4 in enterocytes leads to an inhibition of enterocyte migration and proliferation as well as the induction of enterocyte apoptosis-factors that would be expected to promote intestinal injury while inhibiting intestinal repair. TLR signaling has been shown to be abnormal in several intestinal inflammatory diseases, including Crohn's disease, ulcerative colitis, and necrotizing enterocolitis. This review serves to examine the evidence regarding the patterns of expression and signaling of TLRs in the intestinal mucosa at basal levels and during physiologic stressors to gain insights into the pathogenesis of intestinal inflammation. We conclude that the data reviewed suggest that epithelial TLR signaling-acting in concert with TLR signaling by leukocytes-participates in the development of intestinal inflammation. We further conclude that the evidence reviewed provides a rationale for the development of novel, epithelial-specific, TLR-based agents in the management of diseases of intestinal inflammation.
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Affiliation(s)
- Steven C Gribar
- Division of Pediatric Surgery, Department of Surgery, Children's Hospital of Pittsburgh, Pittsburgh, PA 15213, USA
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Kobayashi R, Okamura S, Ohno T, Saito H, Mori M, Ra C, Okayama Y. Hyperexpression of FcgammaRI and Toll-like receptor 4 in the intestinal mast cells of Crohn's disease patients. Clin Immunol 2007; 125:149-58. [PMID: 17827066 DOI: 10.1016/j.clim.2007.07.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 07/10/2007] [Accepted: 07/15/2007] [Indexed: 01/09/2023]
Abstract
We previously reported that human mast cells (MCs) express high affinity IgG receptor (FcgammaRI) and Toll-like receptor 4 (TLR4) in response to interferon (IFN)-gamma in vitro. The number of MCs is known to increase in Crohn's disease (CD) and ulcerative colitis (UC). We aimed to examine the expression and function of the receptors in these diseases by immunohistochemistry of the colonic mucosae and by in vitro experiments. The density of MCs expressing FcgammaRI, TLR4, or both proteins was significantly higher in CD than in UC or control samples. The density of TNF-alpha(+) MCs expressing FcgammaRI or TLR4 was significantly higher in CD than in control samples. LPS and IgG1 cross-linking synergistically induced a high level of TNF-alpha production in IFN-gamma-treated human MCs. Hyperexpression of FcgammaRI and TLR4 on MCs was related to the high frequency of TNF-alpha expression in CD, suggesting the activation of MCs via these receptors in vivo.
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Affiliation(s)
- Ryota Kobayashi
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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Wang J, Matsukura S, Watanabe S, Adachi M, Suzaki H. Involvement of Toll-like receptors in the immune response of nasal polyp epithelial cells. Clin Immunol 2007; 124:345-52. [PMID: 17602875 DOI: 10.1016/j.clim.2007.05.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 05/14/2007] [Accepted: 05/15/2007] [Indexed: 12/18/2022]
Abstract
Recognition systems employed by airway epithelial cells to respond to microbial exposure include the action of Toll-like receptors (TLRs). We investigated the presence and function of TLR2, 3, and 4 in primary cultures of human nasal polyp epithelial cells. dsRNA stimulation significantly enhanced the expression and secretion of RANTES, IP-10, IL-8, and GM-CSF. LPS also exhibited stimulatory action, but it was much weaker than dsRNA. Peptidoglycan had no significant stimulatory action on the genes. Flow cytometry showed that the nasal polyp epithelial cell mainly expressed TLR3 in an intracellular compartment, but expression of TLR2 and TLR4 was very low on both the cell surface and in the cell. The immune response of primary nasal polyp epithelial cells induced by TLR3 could not be blocked by anti-TLR3 antibody. Among the TLR ligands evaluated, dsRNA, the ligand for TLR3, mediated the strongest pro-inflammatory effects in primary nasal polyp epithelial cells.
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Affiliation(s)
- Jiyun Wang
- Department of Otorhinolaryngology, Showa University School of Medicine, Tokyo, Japan.
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Bogunovic M, Davé SH, Tilstra JS, Chang DTW, Harpaz N, Xiong H, Mayer LF, Plevy SE. Enteroendocrine cells express functional Toll-like receptors. Am J Physiol Gastrointest Liver Physiol 2007; 292:G1770-83. [PMID: 17395901 PMCID: PMC3203538 DOI: 10.1152/ajpgi.00249.2006] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal epithelial cells (IECs) provide a physical and immunological barrier against enteric microbial flora. Toll-like receptors (TLRs), through interactions with conserved microbial patterns, activate inflammatory gene expression in cells of the innate immune system. Previous studies of the expression and function of TLRs in IECs have reported varying results. Therefore, TLR expression was characterized in human and murine intestinal sections, and TLR function was tested in an IEC line. TLR1, TLR2, and TLR4 are coexpressed on a subpopulation of human and murine IECs that reside predominantly in the intestinal crypt and belong to the enteroendocrine lineage. An enteroendocrine cell (EEC) line demonstrated a similar expression pattern of TLRs as primary cells. The murine EEC line STC-1 was activated with specific TLR ligands: LPS or synthetic bacterial lipoprotein. In STC-1 cells stimulated with bacterial ligands, NF-kappaB and MAPK activation was demonstrated. Furthermore, the expression of TNF and macrophage inhibitory protein-2 were induced. Additionally, bacterial ligands induced the expression of the anti-inflammatory gene transforming growth factor-beta. LPS triggered a calcium flux in STC-1 cells, resulting in a rapid increase in CCK secretion. Finally, conditioned media from STC-1 cells inhibited the production of nitric oxide and IL-12 p40 by activated macrophages. In conclusion, human and murine IECs that express TLRs belong to the enteroendocrine lineage. Using a murine EEC model, a broad range of functional effects of TLR activation was demonstrated. This study suggests a potential role for EECs in innate immune responses.
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Affiliation(s)
- Milena Bogunovic
- Div. of Gastroenterology and Hepatology, Univ. of North Carolina School of Medicine, 103 Mason Farm Rd., Campus Box 7032, 7341C MBRB, Chapel Hill, NC 27599-7032, USA
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Various human epithelial cells express functional Toll-like receptors, NOD1 and NOD2 to produce anti-microbial peptides, but not proinflammatory cytokines. Mol Immunol 2007; 44:3100-11. [PMID: 17403538 DOI: 10.1016/j.molimm.2007.02.007] [Citation(s) in RCA: 225] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 01/26/2007] [Accepted: 02/07/2007] [Indexed: 01/01/2023]
Abstract
Epithelial cells may form the first barrier of defense against bacteria in human tissues. We recently revealed that oral epithelial cells generated anti-bacterial factors, such as peptidoglycan recognition proteins (PGRPs) and beta-defensin 2, but not proinflammatory cytokines, such as interleukin-8 (IL-8), upon stimulation with bacterial cell-surface components. In this study, we found clear expressions of Toll-like receptor (TLR)2, TLR3, TLR4, TLR7, NOD1 and NOD2 in oral, tongue, salivary gland, pharyngeal, esophageal, intestinal, cervical, breast, lung, and kidney epithelial cells. However, tongue, salivary gland, pharyngeal, esophageal, intestinal, cervical, breast, lung, and kidney epithelial cells, as well as oral epithelial cells, did not secrete IL-6, IL-8 or monocyte chemoattractant protein-1 in response to chemically synthesized TLR and NOD agonists mimicking microbial components: TLR2 agonistic lipopeptide (Pam3CSSNA), TLR3 agonistic Poly I:C, TLR4 agonistic lipid A (LA-15-PP), TLR7 agonistic single stranded RNA (ssPoly U), NOD1 agonistic iE-DAP (gamma-D-glumtamyl-meso-diaminopimelic acid), and NOD2 agonistic muramyldipeptide (MDP). Although PGRPs on oral epithelial cells were significantly up-regulated upon stimulation with these synthetic components, PGRPs on pharyngeal epithelial cells were only slightly up-regulated, and PGRPs on esophageal, intestinal and cervical epithelial cells were not up-regulated upon stimulation with the components. In contrast, stimulation with synthetic TLRs and NODs ligands induced beta-defensin 2 generation in all epithelial cells examined. These findings indicate that TLR and NOD in various epithelial cells are functional receptors that induce anti-bacterial responses in general without being accompanied by inflammatory responses.
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Sterzenbach T, Lee SK, Brenneke B, von Goetz F, Schauer DB, Fox JG, Suerbaum S, Josenhans C. Inhibitory effect of enterohepatic Helicobacter hepaticus on innate immune responses of mouse intestinal epithelial cells. Infect Immun 2007; 75:2717-28. [PMID: 17371851 PMCID: PMC1932862 DOI: 10.1128/iai.01935-06] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Enterohepatic Helicobacter species infect the intestinal tracts and biliary trees of various mammals, including mice and humans, and are associated with chronic inflammatory diseases of the intestine, gallstone formation, and malignant transformation. The recent analysis of the whole genome sequence of the mouse enterohepatic species Helicobacter hepaticus allowed us to perform a functional analysis of bacterial factors that may play a role in these diseases. We tested the hypothesis that H. hepaticus suppresses or evades innate immune responses of mouse intestinal epithelial cells, which allows this pathogen to induce or contribute to chronic inflammatory disease. We demonstrated in the present study that the innate immune responses of intestinal epithelial cells to lipopolysaccharide (LPS) via Toll-like receptor 4 (TLR4) and to flagellin-mediated activation via TLR5 are reduced by H. hepaticus infection through soluble bacterial factors. In particular, H. hepaticus lysate and the soluble component LPS antagonized TLR4- and TLR5-mediated immune responses of intestinal epithelial cells. H. hepaticus lysate and LPS inhibited development of endotoxin tolerance to Escherichia coli LPS. Suppression of innate immune responses by H. hepaticus LPS thus may affect intestinal responses to the resident microbial flora, epithelial homeostasis, and intestinal inflammatory conditions.
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Affiliation(s)
- Torsten Sterzenbach
- Hannover Medical School, Institute for Medical Microbiology and Hospital Epidemiology, 30625 Hannover, Germany
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