PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-13 (13)
 

Clipboard (0)
None

Select a Filter Below

Journals
Year of Publication
Document Types
1.  Differential Induction of Antimicrobial REGIII by the Intestinal Microbiota and Bifidobacterium breve NCC2950 
Applied and Environmental Microbiology  2013;79(24):7745-7754.
The intestinal microbiota is a key determinant of gut homeostasis, which is achieved, in part, through regulation of antimicrobial peptide secretion. The aim of this study was to determine the efficiency by which members of the intestinal microbiota induce the antimicrobial peptide REGIII and to elucidate the underlying pathways. We showed that germfree mice have low levels of REGIII-γ in their ileum and colon compared to mice with different intestinal microbiota backgrounds. Colonization with a microbiota of low diversity (altered Schaedler flora) did not induce the expression of REGIII-γ as effectively as a complex community (specific pathogen free). Monocolonization with the probiotic Bifidobacterium breve, but not with the nonprobiotic commensal Escherichia coli JM83, upregulated REGIII-γ expression. Induction of REGIII-γ by B. breve was abrogated in mice lacking MyD88 and Ticam1 signaling. Both live and heat-inactivated B. breve but not spent culture medium from B. breve induced the expression of REGIII-α, the human ortholog and homolog of REGIII-γ, in human colonic epithelial cells (Caco-2). Taken together, the results suggest that REGIII-γ expression in the intestine correlates with the richness of microbiota composition. Also, specific bacteria such as Bifidobacterium breve NCC2950 effectively induce REGIII production in the intestine via the MyD88-Ticam1 pathway. Treatment with this probiotic may enhance the mucosal barrier and protect the host from infection and inflammation.
doi:10.1128/AEM.02470-13
PMCID: PMC3837813  PMID: 24096422
2.  Testing for gluten-related disorders in clinical practice: The role of serology in managing the spectrum of gluten sensitivity 
Immunoglobulin A tissue transglutaminase is the single most efficient serological test for the diagnosis of celiac disease. It is well known that immunoglobulin A tissue transglutaminase levels correlate with the degree of intestinal damage, and that values can fluctuate in patients over time. Serological testing can be used to identify symptomatic individuals that need a confirmatory biopsy, to screen at-risk populations or to monitor diet compliance in patients previously diagnosed with celiac disease. Thus, interpretation of serological testing requires consideration of the full clinical scenario. Antigliadin tests are no longer recommended for the diagnosis of classical celiac disease. However, our understanding of the pathogenesis and spectrum of gluten sensitivity has improved, and gluten-sensitive irritable bowel syndrome patients are increasingly being recognized. Studies are needed to determine the clinical utility of antigliadin serology in the diagnosis of gluten sensitivity.
PMCID: PMC3088693  PMID: 21523259
Antigliadin antibodies; Antitissue transglutaminase; Celiac disease; Diagnosis; Gluten intolerance; Serology
3.  The intestinal microbiome, probiotics and prebiotics in neurogastroenterology 
Gut Microbes  2013;4(1):17-27.
The brain-gut axis allows bidirectional communication between the central nervous system (CNS) and the enteric nervous system (ENS), linking emotional and cognitive centers of the brain with peripheral intestinal functions. Recent experimental work suggests that the gut microbiota have an impact on the brain-gut axis. A group of experts convened by the International Scientific Association for Probiotics and Prebiotics (ISAPP) discussed the role of gut bacteria on brain functions and the implications for probiotic and prebiotic science. The experts reviewed and discussed current available data on the role of gut microbiota on epithelial cell function, gastrointestinal motility, visceral sensitivity, perception and behavior. Data, mostly gathered from animal studies, suggest interactions of gut microbiota not only with the enteric nervous system but also with the central nervous system via neural, neuroendocrine, neuroimmune and humoral links. Microbial colonization impacts mammalian brain development in early life and subsequent adult behavior. These findings provide novel insights for improved understanding of the potential role of gut microbial communities on psychological disorders, most particularly in the field of psychological comorbidities associated with functional bowel disorders like irritable bowel syndrome (IBS) and should present new opportunity for interventions with pro- and prebiotics.
doi:10.4161/gmic.22973
PMCID: PMC3555881  PMID: 23202796
probiotic; prebiotic; neurogastroenterology; immune; human trials; biomarkers; gastrointestinal tract; microbiota; microbiome
4.  Visceral pain perception is determined by the duration of colitis and associated neuropeptide expression in the mouse 
Gut  2006;56(3):358-364.
Background
Even though inflammation is a traditional tool for the induction of hyperalgesia in many tissues, recent observations suggest that not all inflammatory processes produce this change. Tolerance to colorectal distension (CRD) is reduced in patients with acute ulcerative colitis but is increased in patients with chronic inflammatory bowel disease. This suggests that the nature of the inflammatory infiltrate influences visceral perception.
Aim
To test this hypothesis by assessing responses to CRD in mice with mild, acute or chronic colitis.
Methods
CRD responses were measured in mice with mild non‐specific colitis, and dextran sodium sulphate (DSS)‐induced acute and chronic colitis. Responses were compared with tissue infiltrate and damage, interleukin (IL)1β and myeloperoxidase (MPO) activity and substance P, β‐endorphin and μ opioid receptor (MOR) expression.
Results
Mild and acute colitis were associated with increased responsiveness to CRD. In contrast, CRD responses were not increased in mice with chronic colitis and this difference was not due to altered colonic wall compliance. MPO and IL1β levels were greater in acute than in chronic colitis. Larger increases in tissue substance P were seen in acute than in chronic DSS, whereas CD4 T cells, β‐endorphin and MOR expression were evident only in chronic colitis. An inverse correlation was seen between substance P and MOR in these tissues.
Conclusions
Acute colitis increased responsiveness to CRD and is accompanied by an acute inflammatory infiltrate and increased tissue substance P. Chronic DSS is accompanied by an increase in β‐endorphin and MOR expression, and CD4 T cells, but no change in compliance or CRD responses. We conclude that acute inflammation generates hyperalgesia, whereas chronic inflammation involves infiltration by lymphocytes accompanied by MOR and β‐endorphin up regulation, and this provides an antinociceptive input that restores normal visceral perception.
doi:10.1136/gut.2006.100016
PMCID: PMC1856796  PMID: 17018864
5.  A flexible continuum between adaptive and innate immunity in maintaining host-microbiota mutualism 
Science (New York, N.Y.)  2009;325(5940):617-620.
doi:10.1126/science.1172747
PMCID: PMC3730530  PMID: 19644121
MyD88; TRIF; commensal bacteria; antibodies; innate immunity; intestine; mucosal
6.  Sensitization to Gliadin Induces Moderate Enteropathy and Insulitis in Nonobese Diabetic-DQ8 Mice 
Celiac disease (CD) is frequently diagnosed in patients with type 1 diabetes (T1D), and T1D patients can exhibit Abs against tissue transglutaminase, the auto-antigen in CD. Thus, gliadin, the trigger in CD, has been suggested to have a role in T1D pathogenesis. The objective of this study was to investigate whether gliadin contributes to enteropathy and insulitis in NOD-DQ8 mice, an animal model that does not spontaneously develop T1D. Gliadin-sensitized NOD-DQ8 mice developed moderate enteropathy, intraepithelial lymphocytosis, and barrier dysfunction, but not insulitis. Administration of anti-CD25 mAbs before gliadin-sensitization induced partial depletion of CD25+Foxp3+ T cells and led to severe insulitis, but did not exacerbate mucosal dysfunction. CD4+ T cells isolated from pancreatic lymph nodes of mice that developed insulitis showed increased proliferation and proinflammatory cytokines after incubation with gliadin but not with BSA. CD4+ T cells isolated from nonsensitized controls did not response to gliadin or BSA. In conclusion, gliadin sensitization induced moderate enteropathy in NOD-DQ8 mice. However, insulitis development required gliadin-sensitization and partial systemic depletion of CD25+Foxp3+ T cells. This humanized murine model provides a mechanistic link to explain how the mucosal intolerance to a dietary protein can lead to insulitis in the presence of partial regulatory T cell deficiency.
doi:10.4049/jimmunol.1100854
PMCID: PMC3493154  PMID: 21911598
7.  Between Celiac Disease and Irritable Bowel Syndrome: The “No Man’s Land” of Gluten Sensitivity 
The repertoire of gastrointestinal (GI) symptoms is finite; however, the etiologies and mechanisms underlying symptom generation and perception are diverse and, in many cases, unknown. This review examines the clinical and experimental evidence exploring the putative relationship between gluten sensitivity (GS) and the generation of GI symptoms. It explores the hypothesis that, in a proportion of patients, GS causes functional bowel disorder (FBD)-like symptoms. We propose a model for investigating and understanding the induction of GI symptoms and dysfunction by gluten in FBD and organic disease. We hypothesize that, even in the absence of fully developed celiac disease, gluten can induce symptoms similar to FBD. We discuss the hypothesis that GS and post-infectious irritable bowel syndrome (IBS) provide two triggers that can explain at least part of the spectrum that constitutes IBS, further advancing an understanding of the role of mucosal responses to luminal factors in FBDs. We propose that the animal model of GS in human leukocyte antigen (HLA)-DQ8 mice allows investigation of mucosal pathophysiological changes that occur before the onset of full-blown inflammation in a GS host. A better understanding of how gluten can cause symptoms in sensitive individuals will illuminate the interaction between host genotype, diet, and intestinal microbiota in generating one of the most common GI conditions.
doi:10.1038/ajg.2009.188
PMCID: PMC3480312  PMID: 19455131
8.  Hydrogen sulfide and resolution of acute inflammation: A comparative study utilizing a novel fluorescent probe 
Scientific Reports  2012;2:499.
Hydrogen sulfide is an essential gasotransmitter associated with numerous pathologies. We assert that hydrogen sulfide plays an important role in regulating macrophage function in response to subsequent inflammatory stimuli, promoting clearance of leukocyte infiltrate and reducing TNF-α levels in vivo following zymosan-challenge. We describe two distinct methods of measuring leukocyte hydrogen sulfide synthesis; methylene blue formation following zinc acetate capture and a novel fluorescent sulfidefluor probe. Comparison of these methods, using pharmacological tools, revealed they were complimentary in vitro and in vivo. We demonstrate the application of sulfidefluor probe to spectrofluorimetry, flow cytometry and whole animal imaging, to monitor the regulation of hydrogen sulfide synthesis in vivo during dynamic inflammatory processes. Both methodologies revealed that granulocyte infiltration negatively affects hydrogen sulfide synthesis. Our report offers an insight into the profile of hydrogen sulfide synthesis during inflammation and highlight opportunities raised by the development of novel fluorescent hydrogen sulfide probes.
doi:10.1038/srep00499
PMCID: PMC3391661  PMID: 22787557
9.  Loss of Hepatocyte-Nuclear-Factor-1α Impacts on Adult Mouse Intestinal Epithelial Cell Growth and Cell Lineages Differentiation 
PLoS ONE  2010;5(8):e12378.
Background and Aims
Although Hnf1α is crucial for pancreas and liver functions, it is believed to play a limited functional role for intestinal epithelial functions. The aim of this study was to assess the consequences of abrogating Hnf1α on the maintenance of adult small intestinal epithelial functions.
Methodology/Principal Findings
An Hnf1α knockout mouse model was used. Assessment of histological abnormalities, crypt epithelial cell proliferation, epithelial barrier, glucose transport and signalling pathways were measured in these animals. Changes in global gene expression were also analyzed. Mice lacking Hnf1α displayed increased crypt proliferation and intestinalomegaly as well as a disturbance of intestinal epithelial cell lineages production during adult life. This phenotype was associated with a decrease of the mucosal barrier function and lumen-to-blood glucose delivery. The mammalian target of rapamycin (mTOR) signalling pathway was found to be overly activated in the small intestine of adult Hnf1α mutant mice. The intestinal epithelium of Hnf1α null mice displayed a reduction of the enteroendocrine cell population. An impact was also observed on proper Paneth cell differentiation with abnormalities in the granule exocytosis pathway.
Conclusions/Significance
Together, these results unravel a functional role for Hnf1α in regulating adult intestinal growth and sustaining the functions of intestinal epithelial cell lineages.
doi:10.1371/journal.pone.0012378
PMCID: PMC2927538  PMID: 20808783
10.  Interleukin-15 and NK1.1+ Cells Provide Innate Protection against Acute Salmonella enterica Serovar Typhimurium Infection in the Gut and in Systemic Tissues▿  
Infection and Immunity  2008;77(1):214-222.
Control of bacterial colonization at mucosal surfaces depends on rapid activation of the innate immune system. Interleukin-15 (IL-15) directs the development, maturation, and function of a population of cells positive for NK1.1, such as natural killer (NK) cells, which are critical components of the innate immune defense against several viral and bacterial pathogens. Using IL-15-deficient mice, in vivo depletion of NK1.1+ cells from wild-type mice, and in vivo overexpression of IL-15 from a recombinant adenovirus, we tested the role of IL-15 and NK1.1+ cells in innate protection of the murine gut and reticuloendothelial system from Salmonella enterica serovar Typhimurium infection. IL-15 and the NK1.1+ cell population provided innate protection from serovar Typhimurium in mice at the enteric mucosae and in the reticuloendothelial system during murine typhoid. Interestingly, serovar Typhimurium extensively colonized the gut of IL-15−/− mice and wild-type C57BL/6 mice depleted of NK1.1+ cells prior to infection, even though the animals were not pretreated with antibiotics to reduce colonization resistance and there was an absence of overt inflammation in the colon and cecum. Enhanced dissemination of Salmonella from the gut of mice depleted of NK1.1+ cells correlated with a localized disruption of IL-17 in the colon. These data suggest a relationship between the gut ecosystem and the innate mucosal immune system, which may be linked via IL-15 and NK1.1+ cells.
doi:10.1128/IAI.01066-08
PMCID: PMC2612292  PMID: 19015253
11.  Intestinal microbiota in functional bowel disorders: a Rome foundation report 
Gut  2012;62(1):159-176.
It is increasingly perceived that gut host–microbial interactions are important elements in the pathogenesis of functional gastrointestinal disorders (FGID). The most convincing evidence to date is the finding that functional dyspepsia and irritable bowel syndrome (IBS) may develop in predisposed individuals following a bout of infectious gastroenteritis. There has been a great deal of interest in the potential clinical and therapeutic implications of small intestinal bacterial overgrowth in IBS. However, this theory has generated much debate because the evidence is largely based on breath tests which have not been validated. The introduction of culture-independent molecular techniques provides a major advancement in our understanding of the microbial community in FGID. Results from 16S rRNA-based microbiota profiling approaches demonstrate both quantitative and qualitative changes of mucosal and faecal gut microbiota, particularly in IBS. Investigators are also starting to measure host–microbial interactions in IBS. The current working hypothesis is that abnormal microbiota activate mucosal innate immune responses which increase epithelial permeability, activate nociceptive sensory pathways and dysregulate the enteric nervous system. While we await important insights in this field, the microbiota is already a therapeutic target. Existing controlled trials of dietary manipulation, prebiotics, probiotics, synbiotics and non-absorbable antibiotics are promising, although most are limited by suboptimal design and small sample size. In this article, the authors provide a critical review of current hypotheses regarding the pathogenetic involvement of microbiota in FGID and evaluate the results of microbiota-directed interventions. The authors also provide clinical guidance on modulation of gut microbiota in IBS.
doi:10.1136/gutjnl-2012-302167
PMCID: PMC3551212  PMID: 22730468
Functional gastrointestinal disorders; microbiota; irritable bowel syndrome; small intestinal bacterial overgrowth; breath tests; probiotics; prebiotics; synbiotics; antibiotics
12.  Intraluminal Administration of Poly I:C Causes an Enteropathy That Is Exacerbated by Administration of Oral Dietary Antigen 
PLoS ONE  2014;9(6):e99236.
Systemic administration of polyinosinic:polycytidylic acid (poly I:C), mimics virally-induced activation of TLR3 signalling causing acute small intestine damage, but whether and how mucosal administration of poly I:C causes enteropathy is less clear. Our aim was to investigate the inflammatory pathways elicited after intraluminal administration of poly I:C and determine acute and delayed consequences of this locally induced immune activation. Intraluminal poly I:C induced rapid mucosal immune activation in C57BL/6 mice involving IFNβ and the CXCL10/CXCR3 axis, that may drive inflammation towards a Th1 profile. Intraluminal poly I:C also caused enteropathy and gut dysfunction in gliadin-sensitive NOD-DQ8 mice, and this was prolonged by concomitant oral administration of gliadin. Our results indicate that small intestine pathology can be induced in mice by intraluminal administration of poly I:C and that this is exacerbated by subsequent oral delivery of a relevant dietary antigen.
doi:10.1371/journal.pone.0099236
PMCID: PMC4051664  PMID: 24915573
13.  Loss of Hepatocyte-Nuclear-Factor-4α Affects Colonic Ion Transport and Causes Chronic Inflammation Resembling Inflammatory Bowel Disease in Mice 
PLoS ONE  2009;4(10):e7609.
Background
Hnf4α, an epithelial specific transcriptional regulator, is decreased in inflammatory bowel disease and protects against chemically-induced colitis in mice. However, the precise role of this factor in maintaining normal inflammatory homeostasis of the intestine remains unclear. The aim of this study was to evaluate the sole role of epithelial Hnf4α in the maintenance of gut inflammatory homeostasis in mice.
Methodology/Principal Findings
We show here that specific epithelial deletion of Hnf4α in mice causes spontaneous chronic intestinal inflammation leading to focal areas of crypt dropout, increased cytokines and chemokines secretion, immune cell infiltrates and crypt hyperplasia. A gene profiling analysis in diseased Hnf4α null colon confirms profound genetic changes in cell death and proliferative behaviour related to cancer. Among the genes involved in the immune protection through epithelial barrier function, we identify the ion transporter claudin-15 to be down-modulated early in the colon of Hnf4α mutants. This coincides with a significant decrease of mucosal ion transport but not of barrier permeability in young animals prior to the manifestation of the disease. We confirm that claudin-15 is a direct Hnf4α gene target in the intestinal epithelial context and is down-modulated in mouse experimental colitis and inflammatory bowel disease.
Conclusion
Our results highlight the critical role of Hnf4α to maintain intestinal inflammatory homeostasis during mouse adult life and uncover a novel function for Hnf4α in the regulation of claudin-15 expression. This establishes Hnf4α as a mediator of ion epithelial transport, an important process for the maintenance of gut inflammatory homeostasis.
doi:10.1371/journal.pone.0007609
PMCID: PMC2764139  PMID: 19898610

Results 1-13 (13)