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Hirano T, Nakase H. The Multifaceted Effects of Gut Microbiota on the Immune System of the Intestinal Mucosa. Immuno 2021; 1:583-94. [DOI: 10.3390/immuno1040041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The gut microbiota has diverse microbial components, including bacteria, viruses, and fungi. The interaction between gut microbiome components and immune responses has been studied extensively over the last decade. Several studies have reported the potential role of the gut microbiome in maintaining gut homeostasis and the development of disease. The commensal microbiome can preserve the integrity of the mucosal barrier by acting on the host immune system. Contrastingly, dysbiosis-induced inflammation can lead to the initiation and progression of several diseases through inflammatory processes and oxidative stress. In this review, we describe the multifaceted effects of the gut microbiota on several diseases from the perspective of mucosal immunological responses.
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Wrba L, Ohmann JJ, Eisele P, Chakraborty S, Braumüller S, Braun CK, Klohs B, Schultze A, von Baum H, Palmer A, Huber-Lang M, Halbgebauer R. Remote Intestinal Injury Early After Experimental Polytrauma and Hemorrhagic Shock. Shock 2019; 52:e45-51. [PMID: 30289852 DOI: 10.1097/SHK.0000000000001271] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Dysfunction of the gut-blood barrier plays an important role in many diseases, such as inflammatory bowel disease, hemorrhagic shock (HS), or burn injury. However, little is known about gut barrier dysfunction after hemodynamically instable polytrauma (PT). Therefore, we aimed to evaluate the effects of PT and HS on remote intestinal damage and barrier dysfunction, especially regarding the role of zonula occludens protein 1 (ZO-1) as an important tight junction protein.Male C57BL/6 mice were subjected to either PT (thorax trauma, closed head injury, soft tissue injury, and distal femoral fracture), 60 min of pressure-controlled HS (30 ± 5 mmHg), or PT+HS, or sham procedures.Animals of all trauma groups showed an increase in abdominal girth and dilation of the intestine during the experimental period, which was largest in the PT+HS group. Increased blood-tissue permeability to albumin (assessed by Evans blue dye) was found in the HS group. Experimental groups showed a slight increase in plasma concentration of intestinal fatty acid binding protein and some intestinal damage was histologically detectable. Of note, PT+HS animals revealed significantly reduced expression of ZO-1 in intestinal epithelial cells. In an in-vitro model, stimulation of human colon epithelial cells with peptidoglycan, but not with lipopolysaccharide, resulted in elevated secretion of pro-inflammatory cytokines, reflecting inflammatory activity of the intestinal epithelium.Taken together, PT and HS lead to increased permeability of the gut-blood barrier. Bacterial components may lead to production of inflammatory and chemotactic mediators by gut epithelial cells, underlining the role of the gut as an immunologically active organ.
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Perna A, Hay E, Contieri M, De Luca A, Guerra G, Lucariello A. Adherent-invasive Escherichia coli (AIEC): Cause or consequence of inflammation, dysbiosis, and rupture of cellular joints in patients with IBD? J Cell Physiol 2020; 235:5041-5049. [PMID: 31898324 DOI: 10.1002/jcp.29430] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 12/23/2019] [Indexed: 12/12/2022]
Abstract
There are many factors contributing to the development of gastrointestinal diseases, grouped into genetic, environmental, and lifestyle factors. In recent years attention has fallen on pathogens; in particular, Bacteroides fragilis, Fusobacterium nucleatum, Escherichia coli (E. coli) and Helicobacter pylori have been studied. Several points remain to be clarified, and above all, as regards the adherent-invasive E. coli strains of E. coli, one wonders if they are a cause or a consequence of the disease. In this review, we have tried to clarify some points by examining a series of recent publications regarding the involvement of the bacterium in the pathology, even if other studies are necessary.
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Affiliation(s)
- Angelica Perna
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Eleonora Hay
- Department of Mental and Physical Health and Preventive Medicine, Section of Human Anatomy, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Marcella Contieri
- Department of Mental and Physical Health and Preventive Medicine, Section of Human Anatomy, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Antonio De Luca
- Department of Mental and Physical Health and Preventive Medicine, Section of Human Anatomy, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Germano Guerra
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Angela Lucariello
- Department of Sport Sciences and Wellness, University of Naples "Parthenope", Naples, Italy
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Eshelman MA, Matthews SM, Schleicher EM, Fleeman RM, Kawasawa YI, Stumpo DJ, Blackshear PJ, Koltun WA, Ishmael FT, Yochum GS. Tristetraprolin targets Nos2 expression in the colonic epithelium. Sci Rep 2019; 9:14413. [PMID: 31595002 DOI: 10.1038/s41598-019-50957-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 09/18/2019] [Indexed: 12/15/2022] Open
Abstract
Tristetraprolin (TTP), encoded by the Zfp36 gene, is a zinc-finger protein that regulates RNA stability primarily through association with 3′ untranslated regions (3′ UTRs) of target mRNAs. While TTP is expressed abundantly in the intestines, its function in intestinal epithelial cells (IECs) is unknown. Here we used a cre-lox system to remove Zfp36 in the mouse epithelium to uncover a role for TTP in IECs and to identify target genes in these cells. While TTP was largely dispensable for establishment and maintenance of the colonic epithelium, we found an expansion of the proliferative zone and an increase in goblet cell numbers in the colon crypts of Zfp36ΔIEC mice. Furthermore, through RNA-sequencing of transcripts isolated from the colons of Zfp36fl/fl and Zfp36ΔIEC mice, we found that expression of inducible nitric oxide synthase (iNos or Nos2) was elevated in TTP-knockout IECs. We demonstrate that TTP interacts with AU-rich elements in the Nos2 3′ UTR and suppresses Nos2 expression. In comparison to control Zfp36fl/fl mice, Zfp36ΔIEC mice were less susceptible to dextran sodium sulfate (DSS)-induced acute colitis. Together, these results demonstrate that TTP in IECs targets Nos2 expression and aggravates acute colitis.
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O'Rourke F, Kempf VAJ. Interaction of bacteria and stem cells in health and disease. FEMS Microbiol Rev 2019; 43:162-180. [DOI: 10.1093/femsre/fuz003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/11/2019] [Indexed: 12/11/2022] Open
Affiliation(s)
- Fiona O'Rourke
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, University Hospital, Goethe University, Paul-Ehrlich-Str. 40, D-60596 Frankfurt am Main, Germany
| | - Volkhard A J Kempf
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, University Hospital, Goethe University, Paul-Ehrlich-Str. 40, D-60596 Frankfurt am Main, Germany
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Sánchez Á, Mengíbar M, Fernández M, Alemany S, Heras A, Acosta N. Influence of Preparation Methods of Chitooligosaccharides on Their Physicochemical Properties and Their Anti-Inflammatory Effects in Mice and in RAW264.7 Macrophages. Mar Drugs 2018; 16:E430. [PMID: 30400250 DOI: 10.3390/md16110430] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 10/19/2018] [Accepted: 10/24/2018] [Indexed: 11/17/2022] Open
Abstract
The methods to obtain chitooligosaccharides are tightly related to the physicochemical properties of the end products. Knowledge of these physicochemical characteristics is crucial to describing the biological functions of chitooligosaccharides. Chitooligosaccharides were prepared either in a single-step enzymatic hydrolysis using chitosanase, or in a two-step chemical-enzymatic hydrolysis. The hydrolyzed products obtained in the single-step preparation were composed mainly of 42% fully deacetylated oligomers plus 54% monoacetylated oligomers, and they attenuated the inflammation in lipopolysaccharide-induced mice and in RAW264.7 macrophages. However, chitooligosaccharides from the two-step preparation were composed of 50% fully deacetylated oligomers plus 27% monoacetylated oligomers and, conversely, they promoted the inflammatory response in both in vivo and in vitro models. Similar proportions of monoacetylated and deacetylated oligomers is necessary for the mixtures of chitooligosaccharides to achieve anti-inflammatory effects, and it directly depends on the preparation method to which chitosan was submitted.
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Drolia R, Tenguria S, Durkes AC, Turner JR, Bhunia AK. Listeria Adhesion Protein Induces Intestinal Epithelial Barrier Dysfunction for Bacterial Translocation. Cell Host Microbe 2018; 23:470-484.e7. [PMID: 29606495 DOI: 10.1016/j.chom.2018.03.004] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 12/30/2017] [Accepted: 03/09/2018] [Indexed: 12/24/2022]
Abstract
Intestinal epithelial cells are the first line of defense against enteric pathogens, yet bacterial pathogens, such as Listeria monocytogenes, can breach this barrier. We show that Listeria adhesion protein (LAP) induces intestinal epithelial barrier dysfunction to promote bacterial translocation. These disruptions are attributed to the production of pro-inflammatory cytokines TNF-α and IL-6, which is observed in mice challenged with WT and isogenic strains lacking the surface invasion protein Internalin A (ΔinlA), but not a lap- mutant. Additionally, upon engagement of its surface receptor Hsp60, LAP activates canonical NF-κB signaling, facilitating myosin light-chain kinase (MLCK)-mediated opening of the epithelial barrier via cellular redistribution of the epithelial junctional proteins claudin-1, occludin, and E-cadherin. Pharmacological inhibition of MLCK or NF-κB in cells or genetic ablation of MLCK in mice prevents mislocalization of junctional proteins and L. monocytogenes translocation. Thus, L. monocytogenes uses LAP to exploit epithelial defenses and cross the intestinal epithelial barrier.
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Abstract
Humans swallow a great variety and often large amounts of chemicals as nutrients, incidental food additives and contaminants, drugs, and inhaled particles and chemicals, thus exposing the gastrointestinal tract to many potentially toxic substances. It serves as a barrier in many cases to protect other components of the body from such substances and infections. Fortunately, the gastrointestinal tract is remarkably robust and generally is able to withstand multiple daily assaults by the chemicals to which it is exposed. Some chemicals, however, can affect one or more aspects of the gastrointestinal tract to produce abnormal events that reflect toxicity. It is the purpose of this chapter to evaluate the mechanisms by which toxic chemicals produce their deleterious effects and to determine the consequences of the toxicity on integrity of gastrointestinal structure and function. Probably because of the intrinsic ability of the gastrointestinal tract to resist toxic chemicals, there is a paucity of data regarding gastrointestinal toxicology. It is therefore necessary in many cases to extrapolate toxic mechanisms from infectious processes, inflammatory conditions, ischemia, and other insults in addition to more conventional chemical sources of toxicity.
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Marin M, Holani R, Shah CB, Odeón A, Cobo ER. Cathelicidin modulates synthesis of Toll-like Receptors (TLRs) 4 and 9 in colonic epithelium. Mol Immunol 2017; 91:249-258. [PMID: 28988039 DOI: 10.1016/j.molimm.2017.09.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/12/2017] [Accepted: 09/21/2017] [Indexed: 12/13/2022]
Abstract
Cathelicidin are innate antimicrobial peptides with broad immunomodulatory functions; however, their role in regulating intestinal defenses is not well characterized. This study aimed to investigate the role of cathelicidin modulating expression of Toll-like receptors (TLRs) 4 and 9 in colonic epithelium in response to bacterial patterns. We demonstrated herein that intestinal epithelial cells, when primed by bacterial lipopolysaccharide (LPS), responded to cathelicidin by increased transcription and protein synthesis of TLR4. This cathelicidin-induced response required the interaction of LPS-TLR4 and activation of MAPK signalling pathways. However, cathelicidin blocked TLR9 responses induced by TLR9 ligand CpG oligodeoxynucleotide (CpG ODN) in these colonic epithelial cells. Modulations of TLRs triggered by cathelicidin in intestinal epithelium occurred mainly in the apical compartment of intestinal cells. Activation of TLR4 by ligands in combination with cathelicidin promoted CXCL8 chemokine secretion and epithelial antimicrobial defenses against Escherichia coli. We concluded that cathelicidin selectively modulated synthesis of TLR4 and 9 in intestinal epithelium, but only when cells were exposed to virulence factors, mostly from apical surfaces. Enhanced TLR4 expression promoted by cathelicidin in intestinal epithelium may be crucial for controlling enteric infectious diseases.
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Affiliation(s)
- Maia Marin
- National Scientific and Technical Research Council (CONICET), Argentina
| | - Ravi Holani
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Canada
| | | | - Anselmo Odeón
- Animal Production, Balcarce Experimental Station, National Institute of Agricultural Technology (INTA), Argentina
| | - Eduardo R Cobo
- Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Canada.
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Rösch C, Taverne N, Venema K, Gruppen H, Wells JM, Schols HA. Effects ofin vitrofermentation of barley β-glucan and sugar beet pectin using human fecal inocula on cytokine expression by dendritic cells. Mol Nutr Food Res 2016; 61. [DOI: 10.1002/mnfr.201600243] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/14/2016] [Accepted: 06/19/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Christiane Rösch
- Laboratory of Food Chemistry; Wageningen University; Wageningen the Netherlands
- Top Institute Food and Nutrition; Wageningen the Netherlands
| | - Nico Taverne
- Host Microbe Interactomics; Wageningen University; Wageningen the Netherlands
| | - Koen Venema
- Top Institute Food and Nutrition; Wageningen the Netherlands
- Beneficial Microbes Consultancy; Wageningen the Netherlands
| | - Harry Gruppen
- Laboratory of Food Chemistry; Wageningen University; Wageningen the Netherlands
| | - Jerry M. Wells
- Host Microbe Interactomics; Wageningen University; Wageningen the Netherlands
| | - Henk A. Schols
- Laboratory of Food Chemistry; Wageningen University; Wageningen the Netherlands
- Top Institute Food and Nutrition; Wageningen the Netherlands
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Rigby RJ, Carr J, Orgel K, King SL, Lund PK, Dekaney CM. Intestinal bacteria are necessary for doxorubicin-induced intestinal damage but not for doxorubicin-induced apoptosis. Gut Microbes 2016; 7:414-23. [PMID: 27459363 PMCID: PMC5046166 DOI: 10.1080/19490976.2016.1215806] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Doxorubicin (DOXO) induces significant, but transient, increases in apoptosis in the stem cell zone of the jejunum, followed by mucosal damage involving a decrease in crypt proliferation, crypt number, and villus height. The gastrointestinal tract is home to a vast population of commensal bacteria and numerous studies have demonstrated a symbiotic relationship between intestinal bacteria and intestinal epithelial cells (IEC) in maintaining homeostatic functions of the intestine. However, whether enteric bacteria play a role in DOXO-induced damage is not well understood. We hypothesized that enteric bacteria are necessary for induction of apoptosis and damage associated with DOXO treatment. Conventionally raised (CONV) and germ free (GF) mice were given a single injection of DOXO, and intestinal tissue was collected at 6, 72, and 120 h after treatment and from no treatment (0 h) controls. Histology and morphometric analyses quantified apoptosis, mitosis, crypt depth, villus height, and crypt density. Immunostaining for muc2 and lysozyme evaluated Paneth cells, goblet cells or dual stained intermediate cells. DOXO administration induced significant increases in apoptosis in jejunal epithelium regardless of the presence of enteric bacteria; however, the resulting injury, as demonstrated by statistically significant changes in crypt depth, crypt number, and proliferative cell number, was dependent upon the presence of enteric bacteria. Furthermore, we observed expansion of Paneth and goblet cells and presence of intermediate cells only in CONV and not GF mice. These findings provide evidence that manipulation and/or depletion of the enteric microbiota may have clinical significance in limiting chemotherapy-induced mucositis.
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Affiliation(s)
- Rachael J. Rigby
- Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
| | - Jacquelyn Carr
- Department of Surgery, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Kelly Orgel
- Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina, USA,Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Stephanie L. King
- Department of Molecular Biomedical Sciences, NC State University, Raleigh, North Carolina, USA
| | - P. Kay Lund
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Christopher M. Dekaney
- Department of Surgery, University of North Carolina, Chapel Hill, North Carolina, USA,Department of Molecular Biomedical Sciences, NC State University, Raleigh, North Carolina, USA
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Abstract
Overweight and obesity increase the risk for a number of diseases, namely, cardiovascular diseases, type 2 diabetes, dyslipidemia, premature death, non-alcoholic fatty liver disease as well as different types of cancer. Approximately 1.7 billion people in the world suffer from being overweight, most notably in developed countries. Current research efforts have focused on host and environmental factors that may affect energy balance. It was hypothesized that a microbiota profile specific to an obese host with increased energy-yielding behavior may exist. Consequently, the gut microbiota is becoming of significant research interest in relation to obesity in an attempt to better understand the aetiology of obesity and to develop new methods of its prevention and treatment. Alteration of microbiota composition may stimulate development of obesity and other metabolic diseases via several mechanisms: increasing gut permeability with subsequent metabolic inflammation; increasing energy harvest from the diet; impairing short-chain fatty acids synthesis; and altering bile acids metabolism and FXR/TGR5 signaling. Prebiotics and probiotics have physiologic functions that contribute to the health of gut microbiota, maintenance of a healthy body weight and control of factors associated with obesity through their effects on mechanisms that control food intake, body weight, gut microbiota and inflammatory processes.
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Affiliation(s)
- Nazarii Kobyliak
- Bogomolets National Medical University, T. Shevchenko Boulevard, 13, Kyiv, 01601, Ukraine.
| | - Oleksandr Virchenko
- Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, Kyiv, 01601, Ukraine
| | - Tetyana Falalyeyeva
- Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, Kyiv, 01601, Ukraine
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Abstract
Our understanding of epigenetics in complex diseases is rapidly advancing and increasingly influencing the practice of medicine. Much is known about disruption of chromatin-modifying enzymes in malignant disease, but knowledge of irregular epigenetics in immune-driven disorders is just emerging. Epigenetic factors, such as DNA or histone modifications, are indispensable for precise gene expression in diverse immune cell types. Thus a disruption of epigenetic landscapes likely has a large impact on immune homeostasis. Moreover, the low concordance rates for most autoimmune diseases suggest that epigenetics contribute to immune tolerance disturbance. Here we review the important role of epigenetics for initiation, maintenance, tolerance, and training of immune responses. We discuss evolving evidence that DNA/histone modifications and chromatin-modifying enzymes are altered in immune-based diseases. Furthermore, we explore the potential of small molecules targeting epigenetic machinery, some of which are already used in oncology, as a way to reset the immune response in disease.
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Abstract
The development, existence, and functioning of numerous animals and plants depend on their symbiotic interactions with other organisms, mainly microorganisms. In return, the symbionts benefit from safe habitats and nutrient-rich environments provided by their hosts. In these interactions, genetic changes in either of the partners may provide fitness advantages and become subjects to natural selection. Recent findings suggest that epigenetic changes, heritable or within the organism's life time, in either of the partners play significant roles in the establishment of symbiotic relationships. In this review, a variety of epigenetic effects underlying the most common host-symbiont interactions will be examined to determine to what extent these effects are shared in various interactions and how the epigenetic pathways could possibly be manipulated to benefit the interacting symbionts.
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Affiliation(s)
- Sassan Asgari
- Australian Infectious Disease Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD, Australia
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Mallet JF, Graham É, Ritz BW, Homma K, Matar C. Active Hexose Correlated Compound (AHCC) promotes an intestinal immune response in BALB/c mice and in primary intestinal epithelial cell culture involving toll-like receptors TLR-2 and TLR-4. Eur J Nutr 2016; 55:139-46. [PMID: 25596849 DOI: 10.1007/s00394-015-0832-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/08/2015] [Indexed: 01/13/2023]
Abstract
PURPOSE Active Hexose Correlated Compound (AHCC(®)) is a cultured mushroom extract that is commercially available and promoted for immune support. Available data suggest that AHCC supplementation affects immune cell populations and immune outcomes, including natural killer cell response to infection. The mechanism by which AHCC exerts its effects is not well understood. The present work aimed to characterize the immunomodulatory activity of AHCC in the gut and to study the effects of AHCC on toll-like receptor (TLR) signaling in intestinal epithelial cells (IECs). METHODS BALB/c mice were fed AHCC by gavage. In vivo activities were assessed by immunohistochemistry and cytokine production. The effects of AHCC on ex vivo primary cell culture from IECs were examined after challenge with LPS or E. coli alone or in the presence of anti-TLR-2 and TLR-4 blocking antibodies. RESULTS Feeding AHCC resulted in increased IgA+ cells in the intestine and increased sIgA, IL-10, and IFN-γ in the intestinal fluid. In IECs, contact with AHCC increased IL-6 production but not to the pro-inflammatory level of positive controls, LPS and E. coli. Blocking TLR-2 and TLR-4 reduced the induction of IL-6 by AHCC, suggesting that these innate receptors are involved in generating the immune response of IECs to AHCC. CONCLUSIONS AHCC may play a role in the orchestration of immune response and the maintenance of immune homeostasis in part by priming the TLR-2 and TLR-4 gate at the intestinal epithelium. Such a response is likely due to the recognition of non-pathogenic food-associated molecular patterns (FAMPs) such as those found associated with other mushroom or yeast-derived compounds.
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Mehta S, Jeffrey KL. Beyond receptors and signaling: epigenetic factors in the regulation of innate immunity. Immunol Cell Biol 2015; 93:233-44. [PMID: 25559622 DOI: 10.1038/icb.2014.101] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 10/31/2014] [Indexed: 12/14/2022]
Abstract
The interaction of innate immune cells with pathogens leads to changes in gene expression that elicit our body's first line of defense against infection. Although signaling pathways and transcription factors have a central role, it is becoming increasingly clear that epigenetic factors, in the form of DNA or histone modifications, as well as noncoding RNAs, are critical for generating the necessary cell lineage as well as context‐specific gene expression in diverse innate immune cell types. Much of the epigenetic landscape is set during cellular differentiation; however, pathogens and other environmental triggers also induce changes in histone modifications that can either promote tolerance or ‘train’ innate immune cells for a more robust antigen‐independent secondary response. Here we review the important contribution of epigenetic factors to the initiation, maintenance and training of innate immune responses. In addition, we explore how pathogens have hijacked these mechanisms for their benefit and the potential of small molecules targeting chromatin machinery as a way to boost or subdue the innate immune response in disease. The March 2015 issue contains a Special Feature on the epigenetic mechanisms underlying health and disease. Epigenetic modifications to chromatin influence the transcriptional status of our genes. Thus, understanding the epigenetic mechanisms that regulate immune cell fate are of great importance as they will provide insight into not only how to boost immune responses but also alter harmful ones such as autoimmunity and cancer. Immunology and Cell Biology thanks the coordinators of this Special Feature ‐ Rhys Allan ‐ for his planning and input.
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Thagia I, Shaw EJ, Smith E, Else KJ, Rigby RJ. Intestinal epithelial suppressor of cytokine signaling 3 enhances microbial-induced inflammatory tumor necrosis factor-α, contributing to epithelial barrier dysfunction. Am J Physiol Gastrointest Liver Physiol 2015; 308:G25-31. [PMID: 25377316 PMCID: PMC4281689 DOI: 10.1152/ajpgi.00214.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A single layer of intestinal epithelial cells (IEC) lines the entire gastrointestinal tract and provides the first line of defense and barrier against an abundance of microbial stimuli. IEC homeostasis and repair are mediated through microbe-sensing Toll-like receptor (TLR)-induced inflammatory pathways. Increasing evidence supports a role of suppressor of cytokine signaling 3 (SOCS3) as a modulator of IEC turnover, balancing controlled repair and replenishment with excessive IEC proliferation predisposing to dysplasia and cancer. Our data indicate that SOCS3 can limit microbial-induced IEC repair, potentially through promoting tumor necrosis factor-α (TNF-α) and limiting TNFR2 expression. Activation of TLR5 signaling pathways, compared with other TLR, increases TNF-α mRNA in a dose-dependent manner and SOCS3 enhances TLR5-induced TNF-α. We also show that flagellin promotes transcription of TNFR2 and that SOCS3 limits this expression, presenting a mechanism of SOCS3 action. Our data also support the role of microbial ligands in epithelial wound healing and suggest that a functional consequence of increased TNF-α is reduced wound healing. These results provide further evidence to support the regulatory role of epithelial SOCS3 in intestinal health and suggest that the increased expression of SOCS3 observed in IBD may serve to perpetuate "inflammation" by promoting TNF-α production and limiting epithelial repair in response to commensal microflora.
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Affiliation(s)
- Imtiyaz Thagia
- 1Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK; and
| | - Elisabeth J. Shaw
- 1Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK; and
| | - Emily Smith
- 1Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK; and
| | - Kathryn J. Else
- 2Faculty of Life Sciences, Manchester University, Manchester, UK
| | - Rachael J. Rigby
- 1Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK; and
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Vastano V, Pagano A, Fusco A, Merola G, Sacco M, Donnarumma G. The Lactobacillus plantarum Eno A1 Enolase Is Involved in Immunostimulation of Caco-2 Cells and in Biofilm Development. Adv Exp Med Biol 2016; 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] [What about the content of this article? (0)] [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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Graves CL, Harden SW, LaPato M, Nelson M, Amador B, Sorenson H, Frazier CJ, Wallet SM. A method for high purity intestinal epithelial cell culture from adult human and murine tissues for the investigation of innate immune function. J Immunol Methods 2014; 414:20-31. [PMID: 25193428 PMCID: PMC4384334 DOI: 10.1016/j.jim.2014.08.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 08/22/2014] [Accepted: 08/25/2014] [Indexed: 12/29/2022]
Abstract
Intestinal epithelial cells (IECs) serve as an important physiologic barrier between environmental antigens and the host intestinal immune system. Thus, IECs serve as a first line of defense and may act as sentinel cells during inflammatory insults. Despite recent renewed interest in IEC contributions to host immune function, the study of primary IEC has been hindered by lack of a robust culture technique, particularly for small intestinal and adult tissues. Here, a novel adaptation for culture of primary IEC is described for human duodenal organ donor tissue as well as duodenum and colon of adult mice. These epithelial cell cultures display characteristic phenotypes and are of high purity. In addition, the innate immune function of human primary IEC, specifically with regard to Toll-like receptor (TLR) expression and microbial ligand responsiveness, is contrasted with a commonly used intestinal epithelial cell line (HT-29). Specifically, TLR expression at the mRNA level and production of cytokine (IFNγ and TNFα) in response to TLR agonist stimulation is assessed. Differential expression of TLRs as well as innate immune responses to ligand stimulation is observed in human-derived cultures compared to that of HT-29. Thus, use of this adapted method to culture primary epithelial cells from adult human donors and from adult mice will allow for more appropriate studies of IECs as innate immune effectors.
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Affiliation(s)
- Christina L Graves
- Department of Oral Biology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL, USA; Department of Periodontology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL 32610-0434, USA.
| | - Scott W Harden
- Department of Oral Biology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL, USA; Department of Neuroscience, College of Medicine, University of Florida, P.O. Box 100244, Gainesville 32610, FL, USA.
| | - Melissa LaPato
- Department of Periodontology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL 32610-0434, USA.
| | - Michael Nelson
- Department of Oral Biology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL, USA; Department of Periodontology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL 32610-0434, USA.
| | - Byron Amador
- Department of Periodontology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL 32610-0434, USA.
| | - Heather Sorenson
- Department of Periodontology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL 32610-0434, USA.
| | - Charles J Frazier
- Department of Neuroscience, College of Medicine, University of Florida, P.O. Box 100244, Gainesville 32610, FL, USA; Department of Pharmacodynamics, College of Medicine, University of Florida, P.O. Box 100244, Gainesville, FL 32610, USA.
| | - Shannon M Wallet
- Department of Oral Biology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL, USA; Department of Periodontology, College of Dentistry, University of Florida, P.O. Box 100434, Gainesville, FL 32610-0434, USA.
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Nigro G, Rossi R, Commere PH, Jay P, Sansonetti PJ. The cytosolic bacterial peptidoglycan sensor Nod2 affords stem cell protection and links microbes to gut epithelial regeneration. Cell Host Microbe 2014; 15:792-8. [PMID: 24882705 DOI: 10.1016/j.chom.2014.05.003] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 03/11/2014] [Accepted: 04/08/2014] [Indexed: 12/13/2022]
Abstract
The intestinal crypt is a site of potential interactions between microbiota products, stem cells, and other cell types found in this niche, including Paneth cells, and thus offers a potential for commensal microbes to influence the host epithelium. However, the complexity of this microenvironment has been a challenge to deciphering the underlying mechanisms. We used in vitro cultured organoids of intestinal crypts from mice, reinforced with in vivo experiments, to examine the crypt-microbiota interface. We find that within the intestinal crypt, Lgr5(+) stem cells constitutively express the cytosolic innate immune sensor Nod2 at levels much higher than in Paneth cells. Nod2 stimulation by its bona fide agonist, muramyl-dipeptide (MDP), a peptidoglycan motif common to all bacteria, triggers stem cell survival, which leads to a strong cytoprotection against oxidative stress-mediated cell death. Thus, gut epithelial restitution is Nod2 dependent and triggered by the presence of microbiota-derived molecules.
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Affiliation(s)
- Giulia Nigro
- Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75015 Paris, France; INSERM U 786, Institut Pasteur, 75015 Paris, France
| | - Raffaella Rossi
- Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75015 Paris, France; Institut de Génomique Fonctionnelle, CNRS UMR 5203, Inserm U661, 34000 Montpellier, France
| | | | - Philippe Jay
- Institut de Génomique Fonctionnelle, CNRS UMR 5203, Inserm U661, 34000 Montpellier, France
| | - Philippe J Sansonetti
- Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75015 Paris, France; INSERM U 786, Institut Pasteur, 75015 Paris, France; Chaire de Microbiologie et Maladies Infectieuses, Collège de France, 75005 Paris, France.
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Sukhotnik I, Pollak Y, Coran AG, Pilatov J, Bejar J, Mogilner JG, Berkowitz D. Glutamine attenuates the inhibitory effect of methotrexate on TLR signaling during intestinal chemotherapy-induced mucositis in a rat. Nutr Metab (Lond) 2014; 11:17. [PMID: 24742067 PMCID: PMC4005622 DOI: 10.1186/1743-7075-11-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 03/22/2014] [Indexed: 12/22/2022] Open
Abstract
Toll-like receptor 4 (TLR-4) is crucial in maintaining intestinal epithelial homeostasis, participates in a vigorous signaling process and heightens inflammatory cytokine output. The objective of this study was to determine the effects of glutamine (GLN) on TLR-4 signaling in intestinal mucosa during methotrexate (MTX)-induced mucositis in a rat. Male Sprague-Dawley rats were randomly assigned to one of four experimental groups of 8 rats each: 1) control rats; 2) CONTR-GLN animals were treated with oral glutamine given in drinking water (2%) 48 hours before and 72 hours following vehicle injection; 3) MTX-rats were treated with a single IP injection of MTX (20 mg/kg); and 4) MTX-GLN rats were pre-treated with oral glutamine similar to group B, 48 hours before and 72 hours after MTX injection. Intestinal mucosal damage, mucosal structural changes, enterocyte proliferation and enterocyte apoptosis were determined 72 hours following MTX injection. The expression of TLR-4, MyD88 and TRAF6 in the intestinal mucosa was determined using real time PCR, Western blot and immunohistochemistry. MTX-GLN rats demonstrated a greater jejunal and ileal mucosal weight and mucosal DNA, greater villus height in ileum and crypt depth and index of proliferation in jejunum and ileum, compared to MTX animals. The expression of TLR-4 and MyD88 mRNA and protein in the mucosa was significantly lower in MTX rats versus controls animals. The administration of GLN increased significantly the expression of TLR-4 and MyD88 (vs the MTX group). In conclusion, treatment with glutamine was associated with up-regulation of TLR-4 and MyD88 expression and a concomitant decrease in intestinal mucosal injury caused by MTX-induced mucositis in a rat.
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Affiliation(s)
- Igor Sukhotnik
- The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Laboratory of intestinal adaptation and recovery, Haifa, Israel
- Department of Pediatric Surgery, Bnai Zion Medical Center, 47 Golomb St., P.O.B. 4940, Haifa 31048, Israel
| | - Yulia Pollak
- The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Laboratory of intestinal adaptation and recovery, Haifa, Israel
| | - Arnold G Coran
- Section of Pediatric Surgery C.S. Mott Children’s Hospital and University of Michigan Medical School, Ann Arbor, MI, USA
| | - Janna Pilatov
- The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Laboratory of intestinal adaptation and recovery, Haifa, Israel
| | - Jacob Bejar
- Pathology, Bnai Zion Medical Center, Haifa, Israel
| | - Jorge G Mogilner
- Department of Pediatric Surgery, Bnai Zion Medical Center, 47 Golomb St., P.O.B. 4940, Haifa 31048, Israel
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22
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Barreda DR, Konowalchuk JD, Rieger AM, Wong ME, Havixbeck JJ. Triennial Growth Symposium--Novel roles for vitamin D in animal immunity and health. J Anim Sci 2014; 92:930-8. [PMID: 24665105 DOI: 10.2527/jas.2013-7341] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Recent years have seen significant advances in the generation, validation, and implementation of nutritional supplements for food production animals. Examination of their impact on animal performance and health requires collaboration among animal scientists, nutritionists, biochemists, immunologists, veterinarians, and others. Each provides a unique perspective on the mechanisms of action, short and long-term impacts, and most effective strategies for implementation into continuously evolving industrial practices. In this review we provide a comparative immunology perspective on the impact of vitamin D on animal performance and health, describe the differential contributions of vitamin D3 and of a commercial hydroxylated version of vitamin D3, 25-hydroxyvitamin D3 (25(OH)D3 or HyD) to swine immunity, and highlight recent advances in the technologies that can be used to dissect the cellular and molecular mechanisms that impact production animal immunity and health. Among others, we pay particular attention to how these novel approaches help decrease the variability often observed in immune-associated datasets. From a practical perspective, this is critical for evaluation of in vivo effects for this nutritional supplement as small but meaningful changes to specific immune responses are typical under normal physiological conditions. Furthermore, as the range of reagents and technologies expands for comparative animal models, it is imperative that continued efforts are placed on the capacity to compare results across different experimental platforms.
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Affiliation(s)
- D R Barreda
- Department of Agricultural, Food and Nutritional Science
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23
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Tsai JC, Lin YW, Huang CY, Lin CY, Tsai YT, Shih CM, Lee CY, Chen YH, Li CY, Chang NC, Lin FY, Tsai CS. The role of calpain-myosin 9-Rab7b pathway in mediating the expression of Toll-like receptor 4 in platelets: a novel mechanism involved in α-granules trafficking. PLoS One 2014; 9:e85833. [PMID: 24489676 PMCID: PMC3904858 DOI: 10.1371/journal.pone.0085833] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 12/02/2013] [Indexed: 01/26/2023] Open
Abstract
Toll-like receptors (TLRs) plays a critical role in innate immunity. In 2004, Aslam R. and Shiraki R. first determined that murine and human platelets express functional TLRs. Additionally, Andonegui G. demonstrated that platelets express TLR4, which contributes to thrombocytopenia. However, the underlying mechanisms of TLR4 expression by platelets have been rarely explored until now. The aim of this study was to identify the mechanism of TLR4 expression underlying thrombin treatment. The human washed platelets were used in this study. According to flowcytometry and western blot analysis, the surface levels of TLR4 were significantly enhanced in thrombin-activated human platelets and decreased by TMB-8, calpeptin, and U73122, but not Y27632 (a Rho-associated protein kinase ROCK inhibitor) indicating that thrombin-mediated TLR4 expression was modulated by PAR/PLC pathway, calcium and calpain. Co-immunoprecipitation (co-IP) assay demonstrated that the interaction between TLR4 and myosin-9 (a substrate of calpain) was regulated by calpain; cleavage of myosin-9 enhanced TLR4 expression in thrombin treated platelets. Transmission electron microscope data indicated that human platelets used α-granules to control TLR4 expression; the co-IP experiment suggested that myosin-9 did not coordinate with Rab7b to negatively regulate TLR4 trafficking in thrombin treated platelets. In summary, phospholipase Cγ-calpain-myosin 9-Rab7b axis was responsible for the mechanism underlying the regulation of TLR4 containing α-granules trafficking in thrombin-stimulated platelets, which was involved in coagulation.
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Affiliation(s)
- Jui-Chi Tsai
- Graduate Institute of Medical Sciences, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
- Departments of Internal Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yi-Wen Lin
- Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Chun-Yao Huang
- Departments of Internal Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei, Taiwan
| | - Chih-Yuan Lin
- Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yi-Ting Tsai
- Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Chun-Min Shih
- Departments of Internal Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei, Taiwan
| | - Chung-Yi Lee
- Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yung-Hsiang Chen
- Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan
| | - Chi-Yuan Li
- Graduate Institute of Clinical Medical Sciences, China Medical University, Taichung, Taiwan
- Department of Anesthesiology, China Medical University Hospital, Taichung, Taiwan
| | - Nen-Chung Chang
- Departments of Internal Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei, Taiwan
| | - Feng-Yen Lin
- Departments of Internal Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei, Taiwan
- * E-mail: (FYL); (CST)
| | - Chien-Sung Tsai
- Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
- * E-mail: (FYL); (CST)
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24
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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] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Wang X, Wang S, Li Y, Wang F, Yang X, Yao J. Sulfated Astragalus polysaccharide can regulate the inflammatory reaction induced by LPS in Caco2 cells. Int J Biol Macromol 2013; 60:248-52. [PMID: 23751319 DOI: 10.1016/j.ijbiomac.2013.05.037] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 05/30/2013] [Accepted: 05/31/2013] [Indexed: 12/31/2022]
Abstract
This study evaluates the effect of sulfated Astragalus polysaccharide (SAPS) on inflammatory reaction induced by LPS in Caco2 cells. Sulfated modification was conducted using the chlorosulfonic acid-pyridine method. Caco2 cells were cultured with 25, 50 and 100 μg/mL SAPS or 100 μg/mL Astragalus polysaccharide (APS) for 24 h. Then, 1 μg/mL LPS was added for the next 24 h to trigger an inflammatory response. DMEM culture medium was used as a blank control. In present study, LPS stimulation significantly increased the mRNA expression of TNF-α, IL-1β, IL-8 and TLR4, and reduced the expression of ZO-1 and occludin. Compared with the LPS control group, APS (100 μg/mL) or SAPS (100 μg/mL) administration decreased the expression of TNF-α, IL-1β and IL-8. Moreover, 25 μg/mL and 50 μg/mL SAPS down-regulated TNF-α and IL-1β expression. APS administration (100 μg/mL) up-regulated occludin expression, but did not affect ZO-1 expression. However, the expression of ZO-1 and occludin was up-regulated by lower dose SAPS administration (25 μg/mL and 50 μg/mL). Compared with the other groups, the expression of TLR4 was lower in the SAPS group at all concentrations of SAPS. These results suggest that SAPS was to be a more effective anti-inflammatory agent than APS in vitro.
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Affiliation(s)
- Xiaofei Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
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26
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Schuijt TJ, van der Poll T, de Vos WM, Wiersinga WJ. The intestinal microbiota and host immune interactions in the critically ill. Trends Microbiol 2013; 21:221-9. [PMID: 23454077 DOI: 10.1016/j.tim.2013.02.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/28/2013] [Accepted: 02/01/2013] [Indexed: 12/12/2022]
Abstract
The gastrointestinal tract harbors a complex population of microbes that play a fundamental role in the development of the immune system and human health. Besides an important local contribution in the host defense against infections, it has become increasingly clear that intestinal bacteria also modulate immune responses at systemic sites. These new insights can be of profound clinical relevance especially for intensive care medicine where the majority of patients are treated with antibiotics, which have pervasive and long-term effects on the intestinal microbiota. Moreover, considerable progress has been made in defining the role of the intestinal microbiota in both health and disease. In this review, we highlight these aspects and focus on recent key findings addressing the role of intestinal microbiota in antimicrobial defense mechanisms and its impact on intestinal homeostasis in the critically ill.
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Affiliation(s)
- Tim J Schuijt
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands.
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Teghanemt A, Weiss JP, Gioannini TL. Radioiodination of an endotoxin·MD-2 complex generates a novel sensitive, high-affinity ligand for TLR4. Innate Immun 2013; 19:545-60. [PMID: 23439691 DOI: 10.1177/1753425913475688] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A purified complex of metabolically labeled [(3)H]lipooligosaccharide (LOS) and recombinant human myeloid differentiation factor 2 (MD-2), [(3)H]LOS·MD-2, has been used to demonstrate pM affinity binding interactions with soluble TLR4 ectodomain (TLR4ecd). For measurement of the binding parameters of membrane-bound TLR4, we took advantage of the stability of endotoxin·MD-2 and tyrosine(s) present on the surface of MD-2 to radioiodinate LOS·MD-2. Radioiodinated LOS·MD-2 generated a reagent with an estimated 1:1 molar ratio of [(125)I] to sMD-2 with 20-fold higher specific radioactivity and TLR4-activating properties comparable to metabolically-labeled LOS·MD-2. LOS·MD-2[(125)I] and [(3)H]LOS·MD-2 have similar affinities for soluble (FLAG) TLR4ecd and for membrane-bound TLR4 in HEK293T/TLR4 cells. In a similar dose-dependent manner, sMD-2 and LOS·MD-2 inhibit LOS·MD-2[(125)I] binding to TLR4 indicating the pM affinity binding of LOS·MD-2[(125)I] is agonist-independent. LOS·MD-2[(125)I] allowed measurement of low levels of cell-surface human or murine TLR4 expressed by stable cell lines (2000-3000 sites/cell) and quantitatively measures low levels of 'MD-2-free' TLR4 (est. 250 molecules/cell) in cells co-expressing TLR4 and MD-2. Occupation of 50-100 TLR4/cell by LOS·MD-2 is sufficient to trigger measurable TLR4-dependent cell activation. LOS·MD-2[(125)I] provides a powerful reagent to measure quantitatively functional human and murine cell-surface TLR4, including in cells where surface TLR4 is potentially functionally significant but not detectable by other methods.
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Affiliation(s)
- Athmane Teghanemt
- 1Inflammation Program, Department of Internal Medicine, Roy A. and Lucille J. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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Pimentel-Nunes P, Gonçalves N, Boal-Carvalho I, Afonso L, Lopes P, Roncon-Albuquerque R, Henrique R, Moreira-Dias L, Leite-Moreira AF, Dinis-Ribeiro M. Helicobacter pylori induces increased expression of Toll-like receptors and decreased Toll-interacting protein in gastric mucosa that persists throughout gastric carcinogenesis. Helicobacter 2013; 18:22-32. [PMID: 23061653 DOI: 10.1111/hel.12008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Toll-like receptors (TLR) are essential for Helicobacter pylori (HP) recognition. Their role in the progression of gastric lesions leading to cancer is not established. AIM To evaluate for the first time in humans the expression of TLR2, TLR4, and TLR5, as well as the expression of other related molecules in the entire sequence of gastric lesions. METHODS Biopsy samples (n = 80, 48% HP+) from normal mucosa, HP gastritis, metaplasia, dysplasia or adenocarcinoma were obtained from 44 patients. mRNA quantification of TLR2, TLR4, TLR5, Toll-interacting protein (TOLLIP), PPAR-γ, NF-κB, TNF-α, COX-1, COX-2, and CDX-2 was performed by real-time RT-PCR. TLR2, TLR4, and TLR5 protein expression was quantified by immunohistochemistry. RESULTS When compared to normal mucosa (1.0 arbitrary unit (AU)), HP gastritis presented higher expression of TLR2 (2.23 ± 0.36 AU), TLR4 (1.92 ± 0.40 AU) and TNF-α (2.14 ± 0.50 AU) and lower TOLLIP and PPARγ expression (0.72 ± 0.12 AU, p < .05 all genes). Metaplasia and dysplasia/carcinoma presented higher expression of TLR2 (1.66 ± 0.46 and 1.48 ± 0.20 AU, respectively, p < .05), lower expression of TOLLIP (0.66 ± 0.09 and 0.52 ± 0.04 AU, p < .05) and PPARγ (0.73 ± 0.12 and 0.63 ± 0.10 AU, p < .05). The significant trend for decrease in TOLLIP and PPARγ was associated with increasing levels of CDX-2 from normal mucosa to carcinoma (p < .05), translating that in diffuse and higher TLRs protein expression (p < .05). CONCLUSION Gastric carcinogenesis is associated with decreasing levels of TLRs inhibitors and elevated TLRs levels throughout all the spectrum of lesions. Future studies should investigate if modulation of these receptors activity may influence gastric carcinogenesis and tumor progression.
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Affiliation(s)
- Pedro Pimentel-Nunes
- Department of Physiology and Cardiothoracic Surgery, University of Porto, Porto, Portugal.
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Pimentel-Nunes P, Teixeira AL, Pereira C, Gomes M, Brandão C, Rodrigues C, Gonçalves N, Boal-Carvalho I, Roncon-Albuquerque R Jr, Moreira-Dias L, Leite-Moreira AF, Medeiros R, Dinis-Ribeiro M. Functional polymorphisms of Toll-like receptors 2 and 4 alter the risk for colorectal carcinoma in Europeans. Dig Liver Dis 2013; 45:63-9. [PMID: 22999059 DOI: 10.1016/j.dld.2012.08.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/25/2012] [Accepted: 08/08/2012] [Indexed: 12/11/2022]
Abstract
BACKGROUND Colon carcinogenesis is associated with increased expression levels of Toll-like receptor 2 and Toll-like receptor 4. AIM To determine in a Caucasian population the role of Toll-like receptor 2 and Toll-like receptor 4 polymorphisms in colorectal cancer development. METHODS Hospital based multicentre case control study involving 193 colorectal cancer patients and 278 healthy individuals. DNA samples were extracted from blood cells and genotyping of TLR2+597T>C, TLR2-4760T>C, TLR4-3745A>G, TLR2Arg753Gln, TLR4Asp299Gly was performed. Functionality of risk polymorphisms was evaluated through production of TNF-α in cell culture and Toll-like receptors levels quantified by real-time RT-PCR. RESULTS TLR2+597CC homozygous had 5-fold decreased risk (odds ratio (OR)=0.21, 95% CI: 0.09-0.50, p<0.001) and TLR4 299Gly homozygous 3-fold increased risk of colorectal cancer (OR=3.30, 95% CI: 1.18-9.28, p=0.015). In stratified analysis, TLR2+597CC genotype protective effect was even higher in overweight individuals (OR=0.17, 95% CI: 0.06-0.53, p<0.001) and in never smokers (OR=0.11, 95% CI: 0.02-0.51, p=0.001). Also, the increased risk effect for TLR4 299Gly homozygous genotype was higher in overweight individuals (OR=8.67, 95% CI: 1.11-87.85, p=0.011). TLR2+597T>C polymorphism conferred 41% less (p=0.03) and TLR4Asp299Gly 65% more TNF-α production (p=0.02) with no differences in Toll-like receptors levels. CONCLUSION Functional Toll-like receptor 2 and Toll-like receptor 4 polymorphisms significantly alter the risk to have colorectal cancer. Obesity and smoking may influence the risk for colorectal cancer in individuals presenting these genetic profiles.
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Lee MJ, Lee JK, Choi JW, Lee CS, Sim JH, Cho CH, Lee KH, Cho IH, Chung MH, Kim HR, Ye SK. Interleukin-6 induces S100A9 expression in colonic epithelial cells through STAT3 activation in experimental ulcerative colitis. PLoS One 2012; 7:e38801. [PMID: 22962574 PMCID: PMC3433486 DOI: 10.1371/journal.pone.0038801] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 05/10/2012] [Indexed: 12/27/2022] Open
Abstract
Background Intestinal epithelium is essential for maintaining normal intestinal homeostasis; its breakdown leads to chronic inflammatory pathologies, such as inflammatory bowel diseases (IBDs). Although high concentrations of S100A9 protein and interleukin-6 (IL-6) are found in patients with IBD, the expression mechanism of S100A9 in colonic epithelial cells (CECs) remains elusive. We investigated the role of IL-6 in S100A9 expression in CECs using a colitis model. Methods IL-6 and S100A9 expression, signal transducer and activator of transcription 3 (STAT3) phosphorylation, and infiltration of immune cells were analyzed in mice with dextran sulfate sodium (DSS)-induced colitis. The effects of soluble gp130-Fc protein (sgp130Fc) and S100A9 small interfering (si) RNA (si-S100A9) on DSS-induced colitis were evaluated. The molecular mechanism of S100A9 expression was investigated in an IL-6-treated Caco-2 cell line using chromatin immunoprecipitation assays. Results IL-6 concentrations increased significantly in the colon tissues of DSS-treated mice. sgp130Fc or si-S100A9 administration to DSS-treated mice reduced granulocyte infiltration in CECs and induced the down-regulation of S100A9 and colitis disease activity. Treatment with STAT3 inhibitors upon IL-6 stimulation in the Caco-2 cell line demonstrated that IL-6 mediated S100A9 expression through STAT3 activation. Moreover, we found that phospho-STAT3 binds directly to the S100A9 promoter. S100A9 may recruit immune cells into inflamed colon tissues. Conclusions Elevated S100A9 expression in CECs mediated by an IL-6/STAT3 signaling cascade may play an important role in the development of colitis.
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Affiliation(s)
- Min Jeoung Lee
- Department of Pharmacology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jin-Ku Lee
- Department of Pharmacology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Ji Won Choi
- Department of Pharmacology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chang-Seok Lee
- Department of Pharmacology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Ji Hyun Sim
- Department of Anatomy, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chung-Hyun Cho
- Department of Pharmacology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Kwang-Ho Lee
- Department of Biotechnology, College of Biomedical & Health Science, Konkuk University, Chungju, Republic of Korea
| | - Ik-Hyun Cho
- Department of Anatomy, College of Oriental Medicine, Kyung Hee University, Seoul, Republic of Korea
- Institute of Oriental Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Myung-Hee Chung
- Department of Pharmacology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hang-Rae Kim
- Department of Anatomy, Seoul National University College of Medicine, Seoul, Republic of Korea
- * E-mail: (SKY); (HK)
| | - Sang-Kyu Ye
- Department of Pharmacology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
- * E-mail: (SKY); (HK)
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Ghadimi D, Helwig U, Schrezenmeir J, Heller KJ, de Vrese M. Epigenetic imprinting by commensal probiotics inhibits the IL-23/IL-17 axis in an in vitro model of the intestinal mucosal immune system. J Leukoc Biol 2012; 92:895-911. [PMID: 22730546 DOI: 10.1189/jlb.0611286] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The pathophysiology of IBD is characterized by a complex interaction between genes and the environment. Genetic and environmental differences are attributed to the heterogeneity of the disease pathway and to the epigenetic modifications that lead to altered gene expression in the diseased tissues. The epigenetic machinery consists of short interfering RNA, histone modifications, and DNA methylation. We evaluated the effects of Bifidobacterium breve (DSMZ 20213) and LGG (ATCC 53103), as representatives of commensal probiotics on the expression of IL-17 and IL-23, which play an important role in IBD, and on the epigenetic machinery in a 3D coculture model composed of human intestinal HT-29/B6 or T84 cells and PBMCs. The cells were treated with LPS in the presence or absence of bacteria for 48 h, and the expression of IL-17, IL-23, and CD40 at the mRNA and protein levels was assessed using TaqMan qRT-PCR and ELISA, respectively. Western blotting was used to assess the expression of the MyD88, the degradation of IRAK-1 and IκBα, the expression of the NF-κB p50/p65 subunits, the p-p38 MAPK and p-MEK1, as well as histone modifications. NF-κB activity was assessed by NF-κB-dependent luciferase reporter gene assays. The accumulation of Ac-H4 and DNA methylation was quantitatively assessed using colorimetric assays. B. breve and LGG diminished the LPS-induced expression of IL-17, IL-23, CD40, and histone acetylation, while slightly enhancing DNA methylation. These effects were paralleled by a decrease in the nuclear translocation of NF-κB, as demonstrated by a decrease in the expression of MyD88, degradation of IRAK-1 and IκBα expression of the nuclear NF-κB p50/p65 subunits, p-p38 MAPK and p-MEK1, and NF-κB-dependent luciferase reporter gene activity in LPS-stimulated cells. B. breve and LGG may exert their anti-inflammatory effects in the gut by down-regulating the expression of the IBD-causing factors (IL-23/IL-17/CD40) associated with epigenetic processes involving the inhibition of histone acetylation and the optimal enhancement of DNA methylation, reflected in the limited access of NF-κB to gene promoters and reduced NF-κB-mediated transcriptional activation. We describe a new regulatory mechanism in which commensal probiotics inhibit the NF-κB-mediated transcriptional activation of IBD-causing factors (IL-23/IL-17/CD40), thereby simultaneously reducing histone acetylation and enhancing DNA methylation.
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Affiliation(s)
- Darab Ghadimi
- Department of Microbiology and Biotechnology, Max Rubner-Institute, Kiel, Germany.
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Watthanasurorot A, Söderhäll K, Jiravanichpaisal P. A mammalian like interleukin-1 receptor-associated kinase 4 (IRAK-4), a TIR signaling mediator in intestinal innate immunity of black tiger shrimp (Penaeus monodon). Biochem Biophys Res Commun 2012; 417:623-9. [DOI: 10.1016/j.bbrc.2011.12.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 12/05/2011] [Indexed: 12/13/2022]
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Atmar RL, Bernstein DI, Harro CD, Al-Ibrahim MS, Chen WH, Ferreira J, Estes MK, Graham DY, Opekun AR, Richardson C, Mendelman PM. Norovirus vaccine against experimental human Norwalk Virus illness. N Engl J Med 2011; 365:2178-87. [PMID: 22150036 PMCID: PMC3761795 DOI: 10.1056/nejmoa1101245] [Citation(s) in RCA: 381] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND Noroviruses cause epidemic and sporadic acute gastroenteritis. No vaccine is available to prevent norovirus illness or infection. METHODS We conducted a randomized, double-blind, placebo-controlled, multicenter trial to assess the safety, immunogenicity, and efficacy of an investigational, intranasally delivered norovirus viruslike particle (VLP) vaccine (with chitosan and monophosphoryl lipid A as adjuvants) to prevent acute viral gastroenteritis after challenge with a homologous viral strain, Norwalk virus (genotype GI.1). Healthy adults 18 to 50 years of age received two doses of either vaccine or placebo and were subsequently inoculated with Norwalk virus and monitored for infection and gastroenteritis symptoms. RESULTS Ninety-eight persons were enrolled and randomly assigned to receive vaccine (50 participants) or placebo (48 participants), and 90 received both doses (47 participants in the vaccine group and 43 in the placebo group). The most commonly reported symptoms after vaccination were nasal stuffiness, nasal discharge, and sneezing. Adverse events occurred with similar frequency among vaccine and placebo recipients. A Norwalk virus-specific IgA seroresponse (defined as an increase by a factor of 4 in serum antibody levels) was detected in 70% of vaccine recipients. Seventy-seven of 84 participants inoculated with Norwalk virus were included in the per-protocol analysis. Vaccination significantly reduced the frequencies of Norwalk virus gastroenteritis (occurring in 69% of placebo recipients vs. 37% of vaccine recipients, P=0.006) and Norwalk virus infection (82% of placebo recipients vs. 61% of vaccine recipients, P=0.05). CONCLUSIONS This norovirus VLP vaccine provides protection against illness and infection after challenge with a homologous virus. (Funded by LigoCyte Pharmaceuticals and the National Institutes of Health; ClinicalTrials.gov number, NCT00973284.).
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Abstract
Intestinal pathogens have a wide variety of strategies for communicating with host epithelial cells. This review highlights a few key examples of those strategies. Enteropathogenic Escherichia coli (EPEC) use a type III secretion system (T3SS) to alter host ion transport through both transcriptional and post-translational mechanisms. Salmonella use a similar T3SS to invade host cells and modify an intracellular vacuole, which also impacts host vesicle trafficking. Helicobacter pylori use host cell integrins to provide a conformational change which drives the type IV secretion system into the host cell for delivery of CagA. The novel type VI section systems are phage-like apparati that deliver VgrG-1, which causes actin cross-linking and fluid accumulation in a suckling mouse model. An entirely different delivery mechanism is the outer membrane vesicle (OMV) which is composed of bacterial outer membrane wrapped around contents of the periplamsic space. Enterotoxigenic E. coli use OMVs to deliver bundles of heat labile enterotoxin to host cells. Finally we discuss the host responses to these varied methods of communication.
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Affiliation(s)
- Kim Hodges
- Department of Digestive Disease and Nutrition, University of Illinois at Chicago, 840 S. Wood Street, Room 718, Chicago, IL 60612, USA
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35
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Wang YZ, Liang QH, Ramkalawan H, Zhang W, Zhou WB, Xiao B, Tian FF, Yang H, Li J, Zhang Y, Xu NA. Inactivation of TLR9 by a suppressive oligodeoxynucleotides can ameliorate the clinical signs of EAN. Immunol Invest 2011; 41:171-82. [PMID: 21864114 DOI: 10.3109/08820139.2011.604864] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Susceptible-strain animals immunized with P2 peptide could generate the disease of experimental autoimmune neuritis (EAN) with inflammation and demyelination of peripheral nerve. A myriad of transcription factors and inflammatory cytokines have been found to participate in this process; however, the roles of toll-like receptors (TLRs) are poorly understood in EAN. The aim of this study is to explore the role of TLR9 in the pathogenesis of EAN. The EAN was induced in Lewis rat by immunization with P2(53-78) and complete Freund's adjuvant. CpG oligodeoxynucleotides (ODN) (cODN), a suppressive ODN (sODN) and a control non-specific ODN (nODN) were respectively administered to explore the role of TLR9 in EAN both in vivo and vitro. Following immunization up to the peak phase of EAN, EAN rats inoculated with sODN had remarkably better clinical score of EAN and expressed a significantly inhibited TLR9 signaling pathway. Our study suggests that TLR9 may be involved in the pathogenesis of EAN.
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Affiliation(s)
- Yu-Zhong Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha 410008, PR China
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Takahashi K, Sugi Y, Nakano K, Tsuda M, Kurihara K, Hosono A, Kaminogawa S. Epigenetic control of the host gene by commensal bacteria in large intestinal epithelial cells. J Biol Chem 2011; 286:35755-35762. [PMID: 21862578 DOI: 10.1074/jbc.m111.271007] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Intestinal epithelial cells (IECs) are continuously exposed to large numbers of commensal bacteria but are relatively insensitive to them, thereby averting an excessive inflammatory reaction. We have previously reported that the hyporesponsiveness of a human IEC line to LPS was primarily the result of a down-regulation of TLR4 gene transcription through epigenetic mechanisms. In the present study we show that DNA methylation in the 5' region of the TLR4 gene is significantly higher in IECs than in splenic cells in vivo. The methylation was shown to be dependent on the differentiation state of the IECs, as the differentiated IEC population that expressed higher levels of intestinal alkaline phosphatase (IAP) also displayed greater methylation and lower expression of the TLR4 gene than the undifferentiated population. The IAP(high), differentiated population also showed less abundant expression of CDX2, the transcription factor required for the development of the intestine, than the IAP(low), undifferentiated population. Overexpression of CDX2 in an IEC line decreased the methylation level of the TLR4 gene, increased transcriptional promoter activity of the gene, and increased responsiveness to the TLR4 ligand. Furthermore, the methylation level of the TLR4 gene was significantly lower in IECs of the large intestine of germ-free mice than in those of conventional mice, whereas the level in IECs of the small intestine was almost equal between these mice, indicating that commensal bacteria contribute to the maintenance of intestinal symbiosis by controlling epigenetic modification of the host gene in the large intestine.
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Affiliation(s)
- Kyoko Takahashi
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan.
| | - Yutaka Sugi
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan
| | - Kou Nakano
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan
| | - Masato Tsuda
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan
| | - Kenta Kurihara
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan
| | - Akira Hosono
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan
| | - Shuichi Kaminogawa
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa 252-0880, Japan
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Abstract
MicroRNA (miRNA) play important roles in the development and physiological function of hematopoietic stem/progenitor and mature cell lineages. In addition, deregulated miRNA expression and subsequent gene expression changes are associated with hematologic diseases including myelodysplastic syndromes and acute myeloid leukemia. This review focuses on myelopoiesis as a model to highlight the involvement of miRNA in the regulation of normal and malignant cellular signaling pathways. By incorporating miRNA regulation into well-established myeloid signal transduction pathways, we hope to shed light on targetable factors both upstream and downstream of miRNA signaling. These pathway-specific miRNA functions suggest scenarios wherein miRNA-based therapeutics may be beneficial either alone or in combination with current therapies.
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Affiliation(s)
- Sara L Stoffers
- Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA
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Matsumura Y, Mitani A, Suga T, Kamiya Y, Kikuchi T, Tanaka S, Aino M, Noguchi T. Azithromycin may inhibit interleukin-8 through suppression of Rac1 and a nuclear factor-kappa B pathway in KB cells stimulated with lipopolysaccharide. J Periodontol 2011; 82:1623-31. [PMID: 21417583 DOI: 10.1902/jop.2011.100721] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Recent studies have shown that the 15-member macrolide antibiotic azithromycin (AZM) not only has antibacterial activity, but also results in the role of immunomodulator. Interleukin (IL)-8 is an important inflammatory mediator in periodontal disease. However, there have been no reports on the effects of AZM on IL-8 production from human oral epithelium. Therefore, we investigated the effects of AZM on IL-8 production in an oral epithelial cell line. METHODS KB cells were stimulated by Escherichia coli or Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) lipopolysaccharide (LPS) with or without AZM. IL-8 mRNA and protein expression and production in response to LPS were analyzed by quantitative polymerase chain reaction, flow cytometry, and enzyme-linked immunosorbent assay. The activation of nuclear factor-kappa B (NF-κB) and Rac1, which is important for IL-8 expression, was analyzed by enzyme-linked immunosorbent assay and Western blotting, respectively. RESULTS IL-8 mRNA expression, IL-8 production, and NF-κB activation in LPS-stimulated KB cells were inhibited by the addition of AZM. LPS-induced Rac1 activation was also suppressed by AZM. CONCLUSIONS This study suggests that AZM inhibits LPS-induced IL-8 production in an oral epithelial cell line, in part caused by the suppression of Rac1 and NF-κB activation. The use of AZM might provide possible benefits in periodontal therapy, with respect to both its antibacterial action and apparent anti-inflammatory effect.
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Affiliation(s)
- Yusuke Matsumura
- Department of Periodontology, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi, Japan
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Ubeda C, Taur Y, Jenq RR, Equinda MJ, Son T, Samstein M, Viale A, Socci ND, van den Brink MRM, Kamboj M, Pamer EG. Vancomycin-resistant Enterococcus domination of intestinal microbiota is enabled by antibiotic treatment in mice and precedes bloodstream invasion in humans. J Clin Invest 2010; 120:4332-41. [PMID: 21099116 DOI: 10.1172/jci43918] [Citation(s) in RCA: 627] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 09/15/2010] [Indexed: 12/19/2022] Open
Abstract
Bloodstream infection by highly antibiotic-resistant bacteria, such as vancomycin-resistant Enterococcus (VRE), is a growing clinical problem that increasingly defies medical intervention. Identifying patients at high risk for bacterial sepsis remains an important clinical challenge. Recent studies have shown that antibiotics can alter microbial diversity in the intestine. Here, we characterized these effects using 16s rDNA pyrosequencing and demonstrated that antibiotic treatment of mice enabled exogenously administered VRE to efficiently and nearly completely displace the normal microbiota of the small and large intestine. In the clinical setting, we found that intestinal domination by VRE preceded bloodstream infection in patients undergoing allogeneic hematopoietic stem cell transplantation. Our results demonstrate that antibiotics perturb the normal commensal microbiota and set the stage for intestinal domination by bacteria associated with hospital-acquired infections. Thus, high-throughput DNA sequencing of the intestinal microbiota could identify patients at high risk of developing bacterial sepsis.
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Affiliation(s)
- Carles Ubeda
- Infectious Diseases Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
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Wells JM, Rossi O, Meijerink M, van Baarlen P. Epithelial crosstalk at the microbiota-mucosal interface. Proc Natl Acad Sci U S A. 2011;108 Suppl 1:4607-4614. [PMID: 20826446 DOI: 10.1073/pnas.1000092107] [Citation(s) in RCA: 393] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
This article provides an overview of how intestinal epithelial cells (IEC) recognize commensals and how they maintain host-bacterial symbiosis. Endocrine, goblet cells, and enterocytes of the intestinal epithelium express a range of pattern recognition receptors (PRR) to sense the presence of microbes. The best characterized are the Toll-like receptors (TLR) and nucleotide oligomerization domain-like receptors (NLR), which play a key role in pathogen recognition and the induction of innate effectors and inflammation. Several adaptations of PRR signaling have evolved in the gut to avoid uncontrolled and potentially destructive inflammatory responses toward the resident microbiota. PRR signaling in IEC serve to maintain the barrier functions of the epithelium, including the production of secretory IgA (sIgA). Additionally, IECs play a cardinal role in setting the immunosuppressive tone of the mucosa to inhibit overreaction against innocuous luminal antigens. This includes regulation of dendritic cells (DC), macrophage and lymphocyte functions by epithelial secreted cytokines. These immune mechanisms depend heavily on IEC recognition of microbes and are consistent with several studies in knockout mice that demonstrate TLR signaling in the epithelium has a profoundly beneficial role in maintaining homeostasis.
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Abstract
Helicobacter pylori colonizes the majority of persons worldwide, and the ensuing gastric inflammatory response is the strongest singular risk factor for peptic ulceration and gastric cancer. However, only a fraction of colonized individuals ever develop clinically significant outcomes. Disease risk is combinatorial and can be modified by bacterial factors, host responses, and/or specific interactions between host and microbe. Several H. pylori constituents that are required for colonization or virulence have been identified, and their ability to manipulate the host innate immune response will be the focus of this review. Identification of bacterial and host mediators that augment disease risk has profound ramifications for both biomedical researchers and clinicians as such findings will not only provide mechanistic insights into inflammatory carcinogenesis but may also serve to identify high-risk populations of H. pylori-infected individuals who can then be targeted for therapeutic intervention.
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Affiliation(s)
- Richard M Peek
- Division of Gastroenterology, Department of Medicine, Vanderbilt University School of Medicine, and Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37232-2279, USA.
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Buchholz BM, Billiar TR, Bauer AJ. Dominant role of the MyD88-dependent signaling pathway in mediating early endotoxin-induced murine ileus. Am J Physiol Gastrointest Liver Physiol 2010; 299:G531-8. [PMID: 20508155 PMCID: PMC2928536 DOI: 10.1152/ajpgi.00060.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
TLR4 ligation by pathogen-associated molecular patterns, such as Gram-negative bacteria-derived LPS, triggers a nonhematopoietic cell-mediated ileus during early endotoxemia. Our objective was to investigate the quantitative contributions of the two downstream signaling pathways of TLR4, namely the adapter proteins myeloid differentiation primary response gene 88 (MyD88) and Toll-IL-1-resistance (TIR) domain-containing adaptor-inducing IFN-beta (TRIF). Six hours after intraperitoneal injection of highly purified LPS (UP-LPS, 5 mg/kg), in vivo gastrointestinal transit and intestinal muscularis gene transcripts of inflammatory mediators chemokine (C-X-C motif) ligand 10, synonymous IP-10 (CXCL10), granulomonocyte colony stimulating factor (GM-CSF, synonymous CSF-2), IL-1beta, IL-6, IL-10, and inducible NO synthase (iNOS) were assessed in mice with transgenic loss-of-function for MyD88 or TRIF. LPS-induced MyD88 and TRIF mRNA upregulation was quantified within the intestinal muscularis of TLR4-competent and TLR4-mutant mice, and MyD88 mRNA levels were additionally measured in TLR4 bone marrow chimeras. MyD88 deficiency completely protected mice from early endotoxin-induced ileus, while TRIF deficiency partially ameliorated ileus severity. LPS induction of the primary downstream signaling element MyD88 was TLR4 dependent and was derived in equal amounts from both the hematopoietic and the nonhematopoietic cells. Conversely, no induction of TRIF mRNA was detectable. Significant gene induction of all inflammatory mediators was dependent on intracellular signal transduction by MyD88, while the TRIF MyD88-independent pathway predominantly regulated the molecular levels of CXCL10. In summary, MyD88 and TRIF are nonredundant signaling pathways in early endotoxin-induced rodent ileus, but MyD88 is the essential adaptor molecule for transduction of early TLR4-induced ileus and inflammatory signaling. The dependency of ileus on individual adaptor protein pathways is also reflected in the manifestation of specific molecular inflammatory events within the intestinal muscularis externa.
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Affiliation(s)
- Bettina M. Buchholz
- 1Department of Medicine/Gastroenterology, University of Pittsburgh, Pittsburgh, Pennsylvania; ,2Department of Surgery, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany; and
| | - Timothy R. Billiar
- 3Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Anthony J. Bauer
- 1Department of Medicine/Gastroenterology, University of Pittsburgh, Pittsburgh, Pennsylvania;
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Peterson CY, Costantini TW, Loomis WH, Putnam JG, Wolf P, Bansal V, Eliceiri BP, Baird A, Coimbra R. Toll-like receptor-4 mediates intestinal barrier breakdown after thermal injury. Surg Infect (Larchmt) 2010; 11:137-44. [PMID: 20374005 DOI: 10.1089/sur.2009.053] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE Toll-like receptor 4 (TLR-4) activation after sterile injury leads to organ dysfunction at distant sites. We have shown previously that intestinal barrier breakdown and alteration of tight junction proteins follows thermal injury; however, the role of TLR-4 in this process remains unclear. We hypothesized that increased intestinal permeability and barrier breakdown after burns is a TLR-4 dependent process; hence, knocking down the TLR-4 gene would have a protective effect on burn-induced intestinal dysfunction. METHODS Male C57BL/6J (TLR-4 wild type [WT]) and C57BL/10ScN (TLR-4 knockout [KO]) mice were assigned randomly to either 30% total body surface area steam burn or sham injury. At 4 h, permeability to intraluminally administered fluorescein isothiocyanate (FITC)-dextran was assessed by measuring the fluorescence of the serum. Intestinal samples were analyzed for the presence of the tight junction protein occludin by immunoblotting and immunohistochemistry. Tumor necrosis factor (TNF)-alpha concentrations in the serum and intestines were measured by enzyme-linked immunosorbent assay at 2 h post-burn. RESULTS Serum concentrations of FITC-dextran were decreased in TLR-4 KO mice compared with TLR-4 WT mice after burn injury (92.0 micrograms/mL and 264.5 micrograms/mL, respectively; p < 0.05). After injury, no difference in intestinal permeability was observed between the TLR-4 KO mice and the TLR-4 WT sham-treated mice. The TLR-4 KO mice had preservation of occludin concentrations after thermal injury in both immunoblot and immunohistochemistry assays, but concentrations were decreased in TLR-4 WT animals. The serum concentrations of TNF-alpha serum were higher in TLR-4 WT burned animals than in the sham-treated mice. The TLR-4 KO animals had unmeasurable concentrations of TNF-alpha. No differences in TNF-alpha were observed in the intestinal tissue at 2 h. CONCLUSIONS Mice with TLR-4 KO have less intestinal permeability to FITC-dextran than do TLR-4 WT mice after burn injury as a result of alterations in the tight junction protein occludin. These findings suggest that the greater intestinal permeability and barrier breakdown after burn injury is a TLR-4-dependent process. Toll-like receptor 4 may provide a useful target for the prevention and treatment of systemic inflammatory response syndrome and multisystem organ failure after injury.
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Affiliation(s)
- Carrie Y Peterson
- Division of Trauma, Critical Care and Burns, Department of Surgery, University of California, San Diego, San Diego, California 92103-8896, USA
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Pimentel-Nunes P, Soares JB, Roncon-Albuquerque R, Dinis-Ribeiro M, Leite-Moreira AF. Toll-like receptors as therapeutic targets in gastrointestinal diseases. Expert Opin Ther Targets 2010; 14:347-68. [PMID: 20146632 DOI: 10.1517/14728221003642027] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
IMPORTANCE OF THE FIELD Toll-like receptors (TLRs) are innate immunity receptors that recognize several different antigens, initiating immunological/inflammatory responses. Recent evidence associates numerous pathophysiological processes and diseases with dysregulated activation of these receptors, conferring a potential therapeutic value to their modulation. AREAS COVERED IN THIS REVIEW The aim of this systematic review that covers literature from the past 10 years is to address the role of TLRs in the pathophysiology of gastrointestinal (GI) diseases as well as the therapeutic potential of modulating TLRs' signaling pathways in GI pathology. WHAT THE READER WILL GAIN This review shows that TLRs play an important role in the pathophysiology of several GI diseases and that modulating TLRs signaling pathways may have an enormous therapeutic potential. Different methods for modulation of TLRs' activity in GI tract, with direct agonists/antagonists but also with non-specific substances, like antibiotics or probiotics, are presented. TAKE HOME MESSAGE Even though TLRs modulators have been used for therapy in some GI diseases, further research, particularly in humans, is needed in order to establish the precise role of the different TLRs in the diverse GI diseases and to motivate clinical trials that consider TLRs as therapeutic targets in GI pathology.
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Affiliation(s)
- Pedro Pimentel-Nunes
- Department of Physiology, Cardiovascular Research & Development Unit, University of Porto, Al. Prof. Hernâni Monteiro, 4200-319, Portugal.
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Asari A, Kanemitsu T, Kurihara H. Oral administration of high molecular weight hyaluronan (900 kDa) controls immune system via Toll-like receptor 4 in the intestinal epithelium. J Biol Chem 2010; 285:24751-8. [PMID: 20504769 DOI: 10.1074/jbc.m110.104950] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Low molecular weight hyaluronan enhances or induces inflammation through toll-like receptor 4 (TLR-4). However, the effects of high molecular weight hyaluronan (HA900) on TLR-4 are unknown. In this study, HA900 (900 kDa) was administered orally to MRL-lpr/lpr mice, a Th-1-type autoimmune disease model. Lymphoaccumulation of double-negative T cells, which is enhanced by proinflammatory cytokines, was suppressed by HA900 treatment. Cytokine array analysis showed that HA900 treatment enhanced production of interleukin-10, an anti-inflammatory cytokine, and down-regulated chemokine production. HA900 colocalized with TLR-4 on the luminal surface of epithelial cells in the large intestine. These cells are parts of the immune system and express cytokines. DNA array analysis of the tissue from the large intestine showed that HA900 treatment up-regulated suppressor of cytokine signaling 3 (SOCS3) expression and down-regulated pleiotrophin expression. Treatment of cultured double-negative T cells from MRL-lpr/lpr mice with pleiotrophin rescued these cells. SOCS3, which is known to suppress inflammation, was enhanced by HA900 treatment. In TLR-4 knockdown HT29 cells (a cell line derived from large intestinal cells), HA900 did not bind to HT29 cells and did not up-regulate SOCS3 expression. Our results suggest that oral administration of HA900 modulates Th-1-type autoimmune disease and inflammation by up-regulating SOCS3 expression and down-regulating pleiotrophin expression via TLR-4 in intestinal epithelial cells.
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Affiliation(s)
- Akira Asari
- Hyaluronan Research Institute Inc, 4-5-9 Kichijojiminami-cho, Musashino-shi, Tokyo 180-0003, Japan.
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Takahashi K. Interaction between the intestinal immune system and commensal bacteria and its effect on the regulation of allergic reactions. Biosci Biotechnol Biochem 2010; 74:691-5. [PMID: 20378987 DOI: 10.1271/bbb.90962] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The immune system and the commensal bacteria in the intestine, which together form the intestinal symbiotic system, greatly contribute to regulation of allergy. Of the various types of cells constituting the intestinal immune system, this review focuses on epithelial cells and mast cells and the interaction of these cells with commensals. Mast cells express the high affinity IgE receptor FcepsilonRI which is essential to the induction of allergic inflammatory reactions. The molecular mechanisms of transcriptional regulation of genes encoding FcepsilonRI have been clarified. On the other hand, the expression of the molecules involved in microbe recognition is regulated in a specific manner in intestinal epithelial cells, which are continuously exposed to the commensals inhabiting the intestinal lumen, to prevent excessive inflammatory reactions. Microbial components directly regulate the functions of mast cells through Toll-like receptors. These aspects provide targets for the regulation of allergy based on the maintenance of the intestinal symbiotic system.
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Abreu MT. 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: 866] [Impact Index Per Article: 61.9] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Abstract
Mucosal epithelium functions not only as a physical barrier, but also as a regulator of innate and adaptive immune responses against foreign substances and microorganisms. In particular, epithelial cells have been directly implicated in Th2 responses, serving as a critical interface between innate immune responses and Th2 immunity. Emerging studies have revealed the cellular and molecular mechanisms by which the epithelium modulates Th2 responses through the production of a group of epithelial-derived Th2-driving cytokines, including interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin. These epithelial-derived Th2-driving cytokines execute a regulatory function of the epithelium on mucosal immunity by promoting Th2 responses and maintaining the balance of host immune homeostasis and defense against various pathogens. Dysregulation of these Th2-driving cytokines can lead to detrimental Th2-dependent inflammatory responses, often manifested in various forms of allergic and inflammatory diseases.
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Montero Vega M, de Andrés Martín A. The significance of toll-like receptors in human diseases. Allergol Immunopathol (Madr) 2009; 37:252-63. [PMID: 19853360 DOI: 10.1016/j.aller.2009.04.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 04/13/2009] [Indexed: 12/12/2022]
Abstract
Toll-like receptors (TLRs) are a family of transmembrane receptors that have been preserved throughout evolution and which selectively recognize a broad spectrum of microbial components and endogenous molecules released by injured tissue. Identification of these ligands by TLRs triggers signalling pathways which lead to the expression of numerous genes involved in a defensive response. In mammals, the products of these genes initiate inflammation, coordinate the effector functions of innate immunity, instruct and modulate adaptive immunity and initiate tissue repair and regeneration. Different mutations and experimental models which alter TLR function have revealed the significance of these receptors in susceptibility to infection and their involvement in the pathogenesis of a large number of non-infective inflammatory disorders such as cancer, allergy, autoimmunity, inflammatory bowel disease, or atherosclerosis. TLRs are currently viewed as important targets for the development of new vaccines and innovative therapies to prevent and treat human diseases.
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Vamadevan AS, Fukata M, Arnold ET, Thomas LS, Hsu D, Abreu MT. Regulation of Toll-like receptor 4-associated MD-2 in intestinal epithelial cells: a comprehensive analysis. Innate Immun 2009; 16:93-103. [PMID: 19710105 DOI: 10.1177/1753425909339231] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The intestinal epithelium maintains a state of controlled inflammation despite continuous contact with Gram-negative commensal bacteria and lipopolysaccharide (LPS) on its luminal surface. Recognition of LPS by the Toll-like receptor (TLR) 4/MD-2 complex results in pro-inflammatory gene expression and cytokine secretion in intestinal epithelial cells (IECs). We have shown that IECs express low levels of MD-2 and TLR4 and are poorly responsive to LPS. In this study, we did a comprehensive analysis to understand the immune-mediated and epigenetic mechanisms by which IECs down-regulate MD-2 expression. Expression of MD-2 and TLR4 mRNA was examined in human inflammatory bowel disease and intestinal epithelial cell lines (T84, HT-29, Caco-2). Nuclear factor-kappaB transcriptional activation was used as a measure of LPS responsiveness. Intestinal epithelial cells in patients with inflammatory bowel disease exhibited increased expression of MD-2 and TLR4 mRNA. Lipopolysaccharide responsiveness in IECs was polarized to the basolateral membrane. Bisulfite sequencing of the MD-2 promoter demonstrated methylation of CpG dinucleotides. Inhibition of methylation by 5-azacytidine and histone de-actylation by trichostatin A, two forms of epigenetic silencing, resulted in increased mRNA expression of MD-2 in IECs. These results demonstrate various molecular mechanisms by which IECs down-regulate MD-2 and, thereby, protect against dysregulated inflammation to commensal bacteria in the intestinal lumen.
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Affiliation(s)
- Arunan S Vamadevan
- Division of Gastroenterology, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33101, USA
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