Publications by authors named "Heather J Galipeau"

22 Publications

  • Page 1 of 1

Increased Bacterial Proteolytic Activity Detected Before Diagnosis of Ulcerative Colitis.

Inflamm Bowel Dis 2021 Jun 14. Epub 2021 Jun 14.

From the Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada.

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http://dx.doi.org/10.1093/ibd/izab144DOI Listing
June 2021

A Riddle, Wrapped in a Mystery, Inside an Enigma: Another Key to Wheat Sensitivity?

Am J Gastroenterol 2021 05;116(5):943-945

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Canada.

Abstract: Nonceliac gluten sensitivity, or the more preferred term, nonceliac wheat sensitivity (NCWS), is a heterogenous condition that is diagnosed purely on the basis of symptoms and without an understanding of disease mechanisms and triggers. Biomarkers to identify patients and implementation of dietary treatment in a personalized manner are needed. Mansueto et al. identified a population of NCWS patients with associated autoimmune markers and immune activation. The presence of these markers could be used, in combination with other serological tests, to help develop better diagnostic strategies for NCWS.
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http://dx.doi.org/10.14309/ajg.0000000000001241DOI Listing
May 2021

Novel Fecal Biomarkers That Precede Clinical Diagnosis of Ulcerative Colitis.

Gastroenterology 2021 Apr 10;160(5):1532-1545. Epub 2020 Dec 10.

Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada. Electronic address:

Background & Aims: Altered gut microbiota composition and function have been associated with inflammatory bowel diseases, including ulcerative colitis (UC), but the causality and mechanisms remain unknown.

Methods: We applied 16S ribosomal RNA gene sequencing, shotgun metagenomic sequencing, in vitro functional assays, and gnotobiotic colonizations to define the microbial composition and function in fecal samples obtained from a cohort of healthy individuals at risk for inflammatory bowel diseases (pre-UC) who later developed UC (post-UC) and matched healthy control individuals (HCs).

Results: Microbiota composition of post-UC samples was different from HC and pre-UC samples; however, functional analysis showed increased fecal proteolytic and elastase activity before UC onset. Metagenomics identified more than 22,000 gene families that were significantly different between HC, pre-UC, and post-UC samples. Of these, 237 related to proteases and peptidases, suggesting a bacterial component to the pre-UC proteolytic signature. Elastase activity inversely correlated with the relative abundance of Adlercreutzia and other potentially beneficial taxa and directly correlated with known proteolytic taxa, such as Bacteroides vulgatus. High elastase activity was confirmed in Bacteroides isolates from fecal samples. The bacterial contribution and functional significance of the proteolytic signature were investigated in germ-free adult mice and in dams colonized with HC, pre-UC, or post-UC microbiota. Mice colonized with or born from pre-UC-colonized dams developed higher fecal proteolytic activity and an inflammatory immune tone compared with HC-colonized mice.

Conclusions: We have identified increased fecal proteolytic activity that precedes the clinical diagnosis of UC and associates with gut microbiota changes. This proteolytic signature may constitute a noninvasive biomarker of inflammation to monitor at-risk populations that can be targeted therapeutically with antiproteases.
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http://dx.doi.org/10.1053/j.gastro.2020.12.004DOI Listing
April 2021

Aryl hydrocarbon receptor ligand production by the gut microbiota is decreased in celiac disease leading to intestinal inflammation.

Sci Transl Med 2020 10;12(566)

Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.

Metabolism of tryptophan by the gut microbiota into derivatives that activate the aryl hydrocarbon receptor (AhR) contributes to intestinal homeostasis. Many chronic inflammatory conditions, including celiac disease involving a loss of tolerance to dietary gluten, are influenced by cues from the gut microbiota. We investigated whether AhR ligand production by the gut microbiota could influence gluten immunopathology in nonobese diabetic (NOD) mice expressing DQ8, a celiac disease susceptibility gene. NOD/DQ8 mice, exposed or not exposed to gluten, were subjected to three interventions directed at enhancing AhR pathway activation. These included a high-tryptophan diet, gavage with that produces AhR ligands or treatment with an AhR agonist. We investigated intestinal permeability, gut microbiota composition determined by 16 rRNA gene sequencing, AhR pathway activation in intestinal contents, and small intestinal pathology and inflammatory markers. In NOD/DQ8 mice, a high-tryptophan diet modulated gut microbiota composition and enhanced AhR ligand production. AhR pathway activation by an enriched tryptophan diet, treatment with the AhR ligand producer , or pharmacological stimulation using 6-formylindolo (3,2-b) carbazole (Ficz) decreased immunopathology in NOD/DQ8 mice exposed to gluten. We then determined AhR ligand production by the fecal microbiota and AhR activation in patients with active celiac disease compared to nonceliac control individuals. Patients with active celiac disease demonstrated reduced AhR ligand production and lower intestinal AhR pathway activation. These results highlight gut microbiota-dependent modulation of the AhR pathway in celiac disease and suggest a new therapeutic strategy for treating this disorder.
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http://dx.doi.org/10.1126/scitranslmed.aba0624DOI Listing
October 2020

Active thrombin produced by the intestinal epithelium controls mucosal biofilms.

Nat Commun 2019 07 19;10(1):3224. Epub 2019 Jul 19.

IRSD, Université de Toulouse, INSERM, INRA, ENVT, UPS, U1220, CHU Purpan, CS60039, 31024, Toulouse, France.

Proteolytic homeostasis is important at mucosal surfaces, but its actors and their precise role in physiology are poorly understood. Here we report that healthy human and mouse colon epithelia are a major source of active thrombin. We show that mucosal thrombin is directly regulated by the presence of commensal microbiota. Specific inhibition of luminal thrombin activity causes macroscopic and microscopic damage as well as transcriptomic alterations of genes involved in host-microbiota interactions. Further, luminal thrombin inhibition impairs the spatial segregation of microbiota biofilms, allowing bacteria to invade the mucus layer and to translocate across the epithelium. Thrombin cleaves the biofilm matrix of reconstituted mucosa-associated human microbiota. Our results indicate that thrombin constrains biofilms at the intestinal mucosa. Further work is needed to test whether thrombin plays similar roles in other mucosal surfaces, given that lung, bladder and skin epithelia also express thrombin.
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http://dx.doi.org/10.1038/s41467-019-11140-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6642099PMC
July 2019

Duodenal bacterial proteolytic activity determines sensitivity to dietary antigen through protease-activated receptor-2.

Nat Commun 2019 03 13;10(1):1198. Epub 2019 Mar 13.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, L8S 4K1, ON, Canada.

Microbe-host interactions are generally homeostatic, but when dysfunctional, they can incite food sensitivities and chronic diseases. Celiac disease (CeD) is a food sensitivity characterized by a breakdown of oral tolerance to gluten proteins in genetically predisposed individuals, although the underlying mechanisms are incompletely understood. Here we show that duodenal biopsies from patients with active CeD have increased proteolytic activity against gluten substrates that correlates with increased Proteobacteria abundance, including Pseudomonas. Using Pseudomonas aeruginosa producing elastase as a model, we show gluten-independent, PAR-2 mediated upregulation of inflammatory pathways in C57BL/6 mice without villus blunting. In mice expressing CeD risk genes, P. aeruginosa elastase synergizes with gluten to induce more severe inflammation that is associated with moderate villus blunting. These results demonstrate that proteases expressed by opportunistic pathogens impact host immune responses that are relevant to the development of food sensitivities, independently of the trigger antigen.
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http://dx.doi.org/10.1038/s41467-019-09037-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416356PMC
March 2019

Lactobacilli Degrade Wheat Amylase Trypsin Inhibitors to Reduce Intestinal Dysfunction Induced by Immunogenic Wheat Proteins.

Gastroenterology 2019 06 22;156(8):2266-2280. Epub 2019 Feb 22.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada. Electronic address:

Background & Aims: Wheat-related disorders, a spectrum of conditions induced by the ingestion of gluten-containing cereals, have been increasing in prevalence. Patients with celiac disease have gluten-specific immune responses, but the contribution of non-gluten proteins to symptoms in patients with celiac disease or other wheat-related disorders is controversial.

Methods: C57BL/6 (control), Myd88, Ticam1, and Il15 mice were placed on diets that lacked wheat or gluten, with or without wheat amylase trypsin inhibitors (ATIs), for 1 week. Small intestine tissues were collected and intestinal intraepithelial lymphocytes (IELs) were measured; we also investigated gut permeability and intestinal transit. Control mice fed ATIs for 1 week were gavaged daily with Lactobacillus strains that had high or low ATI-degrading capacity. Nonobese diabetic/DQ8 mice were sensitized to gluten and fed an ATI diet, a gluten-containing diet or a diet with ATIs and gluten for 2 weeks. Mice were also treated with Lactobacillus strains that had high or low ATI-degrading capacity. Intestinal tissues were collected and IELs, gene expression, gut permeability and intestinal microbiota profiles were measured.

Results: In intestinal tissues from control mice, ATIs induced an innate immune response by activation of Toll-like receptor 4 signaling to MD2 and CD14, and caused barrier dysfunction in the absence of mucosal damage. Administration of ATIs to gluten-sensitized mice expressing HLA-DQ8 increased intestinal inflammation in response to gluten in the diet. We found ATIs to be degraded by Lactobacillus, which reduced the inflammatory effects of ATIs.

Conclusions: ATIs mediate wheat-induced intestinal dysfunction in wild-type mice and exacerbate inflammation to gluten in susceptible mice. Microbiome-modulating strategies, such as administration of bacteria with ATI-degrading capacity, may be effective in patients with wheat-sensitive disorders.
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http://dx.doi.org/10.1053/j.gastro.2019.02.028DOI Listing
June 2019

Celiac Disease: A Review of Current Concepts in Pathogenesis, Prevention, and Novel Therapies.

Front Pediatr 2018 21;6:350. Epub 2018 Nov 21.

The Diabetes and Celiac Disease Unit, Department of Clinical Sciences, Lund University, Malmö, Sweden.

Our understanding of celiac disease and how it develops has evolved significantly over the last half century. Although traditionally viewed as a pediatric illness characterized by malabsorption, it is now better seen as an immune illness with systemic manifestations affecting all ages. Population studies reveal this global disease is common and, in many countries, increasing in prevalence. These studies underscore the importance of specific HLA susceptibility genes and gluten consumption in disease development and suggest that other genetic and environmental factors could also play a role. The emerging data on viral and bacterial microbe-host interactions and their alterations in celiac disease provides a plausible mechanism linking environmental risk and disease development. Although the inflammatory lesion of celiac disease is complex, the strong HLA association highlights a central role for pathogenic T cells responding to select gluten peptides that have now been defined for the most common genetic form of celiac disease. What remains less understood is how loss of tolerance to gluten occurs. New insights into celiac disease are now providing opportunities to intervene in its development, course, diagnosis, and treatment.
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http://dx.doi.org/10.3389/fped.2018.00350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6258800PMC
November 2018

Commensal microbiota induces colonic barrier structure and functions that contribute to homeostasis.

Sci Rep 2018 09 21;8(1):14184. Epub 2018 Sep 21.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada.

The intestinal barrier encompasses structural, permeability and immune aspects of the gut mucosa that, when disrupted, may contribute to chronic inflammation. Although gnotobiotic studies have demonstrated the effects of microbiota on mucosal and systemic immunity, as well as intestinal barrier architecture and innate immune characteristics, its impact on barrier function remains unclear. We compared germ-free and conventional mice, as well as mice colonized with human fecal microbiota that were followed for 21 days post-colonization. Colonic barrier structure was investigated by immunohistochemistry, molecular and electron microscopy techniques. Permeability was assessed in colon tissue by Ussing chambers, and by serum LPS and MDP detection using TLR4- and NOD2-NFκB reporter assays. Microbiota profile was determined by Illumina 16S rRNA gene sequencing. Low dose dextran sodium sulfate was administered to assess microbiota-induced barrier changes on resistance to colonic injury. Permeability to paracellular probes and mucus layer structure resembled that of conventional mice by day 7 post-colonization, coinciding with reduced claudin-1 expression and transient IL-18 production by intestinal epithelial cells. These post-colonization adaptations were associated with decreased systemic bacterial antigen exposure and reduced susceptibility to intestinal injury. In conclusion, commensal colonization promotes physiological barrier structural and functional adaptations that contribute to intestinal homeostasis.
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http://dx.doi.org/10.1038/s41598-018-32366-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6155058PMC
September 2018

An intact microbiota is required for the gastrointestinal toxicity of the immunosuppressant mycophenolate mofetil.

J Heart Lung Transplant 2018 09 23;37(9):1047-1059. Epub 2018 May 23.

Department of Physiology and Pharmacology, Cumming School of Medicine; Snyder Institute for Chronic Diseases; Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine.

Background: Mycophenolate mofetil (MMF) is commonly prescribed after transplantation and has major advantages over other immunosuppressive drugs, but frequent gastrointestinal (GI) side-effects limit its use. The mechanism(s) underlying MMF-related GI toxicity have yet to be elucidated.

Methods: To investigate MMF-related GI toxicity, experimental mice were fed chow containing MMF (0.563%) and multiple indices of toxicity, including weight loss and colonic inflammation, were measured. Changes in intestinal microbial composition were detected using 16S rRNA Illumina sequencing, and downstream PICRUSt analysis was used to predict metagenomic pathways involved. Germ-free (GF) mice and mice treated with orally administered broad-spectrum antibiotics (ABX) were utilized to interrogate the importance of the microbiota in MMF-induced GI toxicity.

Results: Mice treated with MMF exhibited significant weight loss, related to loss of body fat and muscle, and marked colonic inflammation. MMF exposure was associated with changes in gut microbial composition, as demonstrated by a loss of overall diversity, expansion of Proteobacteria (specifically Escherichia/Shigella), and enrichment of genes involved in lipopolysaccharide (LPS) biosynthesis, which paralleled increased levels of LPS in the feces and serum. MMF-related GI toxicity was dependent on the intestinal microbiota, as MMF did not induce weight loss or colonic inflammation in GF mice. Furthermore, ABX prevented and reversed MMF-induced weight loss and colonic inflammation.

Conclusions: An intact intestinal microbiota is required to initiate and sustain the GI toxicity of MMF. MMF treatment causes dynamic changes in the composition of the intestinal microbiota that may be a targetable driver of the GI side-effects of MMF.
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http://dx.doi.org/10.1016/j.healun.2018.05.002DOI Listing
September 2018

Microbial signals drive pre-leukaemic myeloproliferation in a Tet2-deficient host.

Nature 2018 05 16;557(7706):580-584. Epub 2018 May 16.

Department of Genetics, CHU Sainte-Justine Research Center, Montreal, Quebec, Canada.

Somatic mutations in tet methylcytosine dioxygenase 2 (TET2), which encodes an epigenetic modifier enzyme, drive the development of haematopoietic malignancies. In both humans and mice, TET2 deficiency leads to increased self-renewal of haematopoietic stem cells with a net developmental bias towards the myeloid lineage. However, pre-leukaemic myeloproliferation (PMP) occurs in only a fraction of Tet2 mice and humans with TET2 mutations, suggesting that extrinsic non-cell-autonomous factors are required for disease onset. Here we show that bacterial translocation and increased interleukin-6 production, resulting from dysfunction of the small-intestinal barrier, are critical for the development of PMP in mice that lack Tet2 expression in haematopoietic cells. Furthermore, in symptom-free Tet2 mice, PMP can be induced by disrupting intestinal barrier integrity, or in response to systemic bacterial stimuli such as the toll-like receptor 2 agonist. PMP was reversed by antibiotic treatment and failed to develop in germ-free Tet2 mice, which illustrates the importance of microbial signals in the development of this condition. Our findings demonstrate the requirement for microbial-dependent inflammation in the development of PMP and provide a mechanistic basis for the variation in PMP penetrance observed in Tet2 mice. This study will prompt new lines of investigation that may profoundly affect the prevention and management of haematopoietic malignancies.
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http://dx.doi.org/10.1038/s41586-018-0125-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6238954PMC
May 2018

Lifelong memory responses perpetuate humoral T2 immunity and anaphylaxis in food allergy.

J Allergy Clin Immunol 2017 Dec 16;140(6):1604-1615.e5. Epub 2017 Feb 16.

McMaster Immunology Research Centre (MIRC), Department of Pathology & Molecular Medicine, McMaster University, Hamilton, Ontario, Canada. Electronic address:

Background: A number of food allergies (eg, fish, shellfish, and nuts) are lifelong, without any disease-transforming therapies, and unclear in their underlying immunology. Clinical manifestations of food allergy are largely mediated by IgE. Although persistent IgE titers have been attributed conventionally to long-lived IgE plasma cells (PCs), this has not been directly and comprehensively tested.

Objective: We sought to evaluate mechanisms underlying persistent IgE and allergic responses to food allergens.

Methods: We used a model of peanut allergy and anaphylaxis, various knockout mice, adoptive transfer experiments, and in vitro assays to identify mechanisms underlying persistent IgE humoral immunity over almost the entire lifespan of the mouse (18-20 months).

Results: Contrary to conventional paradigms, our data show that clinically relevant lifelong IgE titers are not sustained by long-lived IgE PCs. Instead, lifelong reactivity is conferred by allergen-specific long-lived memory B cells that replenish the IgE PC compartment. B-cell reactivation requires allergen re-exposure and IL-4 production by CD4 T cells. We define the half-lives of antigen-specific germinal centers (23.3 days), IgE and IgG PCs (60 and 234.4 days, respectively), and clinically relevant cell-bound IgE (67.3 days).

Conclusions: These findings can explain lifelong food allergies observed in human subjects as the consequence of allergen exposures that recurrently activate memory B cells and identify these as a therapeutic target with disease-transforming potential.
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http://dx.doi.org/10.1016/j.jaci.2017.01.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6298600PMC
December 2017

Duodenal Bacteria From Patients With Celiac Disease and Healthy Subjects Distinctly Affect Gluten Breakdown and Immunogenicity.

Gastroenterology 2016 10 30;151(4):670-83. Epub 2016 Jun 30.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada. Electronic address:

Background & Aims: Partially degraded gluten peptides from cereals trigger celiac disease (CD), an autoimmune enteropathy occurring in genetically susceptible persons. Susceptibility genes are necessary but not sufficient to induce CD, and additional environmental factors related to unfavorable alterations in the microbiota have been proposed. We investigated gluten metabolism by opportunistic pathogens and commensal duodenal bacteria and characterized the capacity of the produced peptides to activate gluten-specific T-cells from CD patients.

Methods: We colonized germ-free C57BL/6 mice with bacteria isolated from the small intestine of CD patients or healthy controls, selected for their in vitro gluten-degrading capacity. After gluten gavage, gliadin amount and proteolytic activities were measured in intestinal contents. Peptides produced by bacteria used in mouse colonizations from the immunogenic 33-mer gluten peptide were characterized by liquid chromatography tandem mass spectrometry and their immunogenic potential was evaluated using peripheral blood mononuclear cells from celiac patients after receiving a 3-day gluten challenge.

Results: Bacterial colonizations produced distinct gluten-degradation patterns in the mouse small intestine. Pseudomonas aeruginosa, an opportunistic pathogen from CD patients, exhibited elastase activity and produced peptides that better translocated the mouse intestinal barrier. P aeruginosa-modified gluten peptides activated gluten-specific T-cells from CD patients. In contrast, Lactobacillus spp. from the duodenum of non-CD controls degraded gluten peptides produced by human and P aeruginosa proteases, reducing their immunogenicity.

Conclusions: Small intestinal bacteria exhibit distinct gluten metabolic patterns in vivo, increasing or reducing gluten peptide immunogenicity. This microbe-gluten-host interaction may modulate autoimmune risk in genetically susceptible persons and may underlie the reported association of dysbiosis and CD.
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http://dx.doi.org/10.1053/j.gastro.2016.06.041DOI Listing
October 2016

Intestinal microbiota modulates gluten-induced immunopathology in humanized mice.

Am J Pathol 2015 Nov 9;185(11):2969-82. Epub 2015 Oct 9.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada. Electronic address:

Celiac disease (CD) is an immune-mediated enteropathy triggered by gluten in genetically susceptible individuals. The recent increase in CD incidence suggests that additional environmental factors, such as intestinal microbiota alterations, are involved in its pathogenesis. However, there is no direct evidence of modulation of gluten-induced immunopathology by the microbiota. We investigated whether specific microbiota compositions influence immune responses to gluten in mice expressing the human DQ8 gene, which confers moderate CD genetic susceptibility. Germ-free mice, clean specific-pathogen-free (SPF) mice colonized with a microbiota devoid of opportunistic pathogens and Proteobacteria, and conventional SPF mice that harbor a complex microbiota that includes opportunistic pathogens were used. Clean SPF mice had attenuated responses to gluten compared to germ-free and conventional SPF mice. Germ-free mice developed increased intraepithelial lymphocytes, markers of intraepithelial lymphocyte cytotoxicity, gliadin-specific antibodies, and a proinflammatory gliadin-specific T-cell response. Antibiotic treatment, leading to Proteobacteria expansion, further enhanced gluten-induced immunopathology in conventional SPF mice. Protection against gluten-induced immunopathology in clean SPF mice was reversed after supplementation with a member of the Proteobacteria phylum, an enteroadherent Escherichia coli isolated from a CD patient. The intestinal microbiota can both positively and negatively modulate gluten-induced immunopathology in mice. In subjects with moderate genetic susceptibility, intestinal microbiota changes may be a factor that increases CD risk.
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http://dx.doi.org/10.1016/j.ajpath.2015.07.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4630176PMC
November 2015

Ecobiotherapy Rich in Firmicutes Decreases Susceptibility to Colitis in a Humanized Gnotobiotic Mouse Model.

Inflamm Bowel Dis 2015 Aug;21(8):1883-93

*Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada; †Department of Pathology, and Molecular Medicine, McMaster Immunology Research Centre, McMaster University, Hamilton, ON, Canada; and ‡Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada.

Background: Alterations in the intestinal microbiota, characterized by depletion of anti-inflammatory bacteria, such as Firmicutes, in patients with ulcerative colitis (UC) have prompted interest in microbiota-modulating strategies for this condition. The aim of this study was to evaluate the role of fecal and synthetic human microbial ecosystems, low or enriched in Firmicutes, on colitis susceptibility and host immune responses.

Methods: The microbiota of selected healthy and UC human donors was characterized by culture method and 16S rRNA-based sequencing. Germ-free mice were colonized with fecal or a synthetic ecosystem enriched (healthy donors) or low (UC donors) in Firmicutes. Experimental colitis was induced using dextran sodium sulfate. Colon transcriptome and colon lamina propria cells were evaluated in mice postcolonization by RNA-seq and flow cytometry, respectively, and T helper (TH) 17 differentiation was assessed in vitro.

Results: Mice colonized with microbiota from patients with UC low in Firmicutes had increased sensitivity to colitis compared with mice colonized with fecal or synthetic ecosystems rich in Firmicutes. Microbiota low in Firmicutes increased expression of TH17-related genes and expansion of interleukin-17A-expressing CD4 cells in vivo. Supplementation with bacterial isolates belonging to the Firmicutes phylum abrogated the heightened TH17 responses in vitro.

Conclusions: A microbiota rich in Firmicutes derived from fecal samples of a healthy human donor, or assembled synthetically, downregulated colonic inflammation and TH17 pathways in mice. The results support the use of ecobiotherapy strategies, enriched in Firmicutes, for the prevention or treatment of UC.
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http://dx.doi.org/10.1097/MIB.0000000000000422DOI Listing
August 2015

Novel players in coeliac disease pathogenesis: role of the gut microbiota.

Nat Rev Gastroenterol Hepatol 2015 Sep 9;12(9):497-506. Epub 2015 Jun 9.

Department of Medicine, University of Chicago, 900 East 57th Street, MB#9, Chicago 60637, USA.

Several studies point towards alteration in gut microbiota composition and function in coeliac disease, some of which can precede the onset of disease and/or persist when patients are on a gluten-free diet. Evidence also exists that the gut microbiota might promote or reduce coeliac-disease-associated immunopathology. However, additional studies are required in humans and in mice (using gnotobiotic technology) to determine cause-effect relationships and to identify agents for modulating the gut microbiota as a therapeutic or preventative approach for coeliac disease. In this Review, we summarize the current evidence for altered gut microbiota composition in coeliac disease and discuss how the interplay between host genetics, environmental factors and the intestinal microbiota might contribute to its pathogenesis. Moreover, we highlight the importance of utilizing animal models and long-term clinical studies to gain insight into the mechanisms through which host-microbial interactions can influence host responses to gluten.
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http://dx.doi.org/10.1038/nrgastro.2015.90DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102016PMC
September 2015

Gut microbes and adverse food reactions: Focus on gluten related disorders.

Gut Microbes 2014 ;5(5):594-605

a Farncombe Family Digestive Health Research Institute ; McMaster University ; Hamilton , Canada.

Immediately following birth, the gastrointestinal tract is colonized with a complex community of bacteria, which helps shape the immune system. Under conditions of health, the immune system is able to differentiate between innocuous antigens, including food protein and commensals, and harmful antigens such as pathogens. However, patients with celiac disease (CD) develop an intolerance to gluten proteins which results in a pro-inflammatory T-cell mediated immune response with production of anti-gluten and anti-tissue transglutaminase antibodies. This adaptive immune response, in conjunction with activation of innate inflammatory cells, lead to destruction of the small intestinal mucosa. Overall 30% of the global population has genetic risk to develop CD. However, only a small proportion develop CD, suggesting that additional environmental factors must play a role in disease pathogenesis. Alterations in small intestinal microbial composition have recently been associated with active CD, indicating a possible role for the microbiota in CD. However, studies demonstrating causality are lacking. This review will highlight the recent data on the potential role of the microbiota in CD pathogenesis, the potential mechanisms, and discuss future research directions.
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http://dx.doi.org/10.4161/19490976.2014.969635DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5154254PMC
September 2015

BL-7010 demonstrates specific binding to gliadin and reduces gluten-associated pathology in a chronic mouse model of gliadin sensitivity.

PLoS One 2014 3;9(11):e109972. Epub 2014 Nov 3.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada.

Celiac disease (CD) is an autoimmune disorder in individuals that carry DQ2 or DQ8 MHC class II haplotypes, triggered by the ingestion of gluten. There is no current treatment other than a gluten-free diet (GFD). We have previously shown that the BL-7010 copolymer poly(hydroxyethyl methacrylate-co-styrene sulfonate) (P(HEMA-co-SS)) binds with higher efficiency to gliadin than to other proteins present in the small intestine, ameliorating gliadin-induced pathology in the HLA-HCD4/DQ8 model of gluten sensitivity. The aim of this study was to investigate the efficiency of two batches of BL-7010 to interact with gliadin, essential vitamins and digestive enzymes not previously tested, and to assess the ability of the copolymer to reduce gluten-associated pathology using the NOD-DQ8 mouse model, which exhibits more significant small intestinal damage when challenged with gluten than HCD4/DQ8 mice. In addition, the safety and systemic exposure of BL-7010 was evaluated in vivo (in rats) and in vitro (genetic toxicity studies). In vitro binding data showed that BL-7010 interacted with high affinity with gliadin and that BL-7010 had no interaction with the tested vitamins and digestive enzymes. BL-7010 was effective at preventing gluten-induced decreases in villus-to-crypt ratios, intraepithelial lymphocytosis and alterations in paracellular permeability and putative anion transporter-1 mRNA expression in the small intestine. In rats, BL-7010 was well-tolerated and safe following 14 days of daily repeated administration of 3000 mg/kg. BL-7010 did not exhibit any mutagenic effect in the genetic toxicity studies. Using complementary animal models and chronic gluten exposure the results demonstrate that administration of BL-7010 is effective and safe and that it is able to decrease pathology associated with gliadin sensitization warranting the progression to Phase I trials in humans.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0109972PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4217726PMC
August 2015

Novel role of the serine protease inhibitor elafin in gluten-related disorders.

Am J Gastroenterol 2014 May 8;109(5):748-56. Epub 2014 Apr 8.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Canada.

Objectives: Elafin, an endogenous serine protease inhibitor, modulates colonic inflammation. We investigated the role of elafin in celiac disease (CD) using human small intestinal tissues and in vitro assays of gliadin deamidation. We also investigated the potential beneficial effects of elafin in a mouse model of gluten sensitivity.

Methods: Epithelial elafin expression in the small intestine of patients with active CD, treated CD, and controls without CD was determined by immunofluorescence. Interaction of elafin with human tissue transglutaminase-2 (TG-2) was investigated in vitro. The 33-mer peptide, a highly immunogenic gliadin peptide, was incubated with TG-2 and elafin at different concentrations. The degree of deamidation of the 33-mer peptide was analyzed by liquid chromatography-mass spectrometry. Elafin was delivered to the intestine of gluten-sensitive mice using a recombinant Lactococcus lactis vector. Small intestinal barrier function, inflammation, proteolytic activity, and zonula occludens-1 (ZO-1) expression were assessed.

Results: Elafin expression in the small intestinal epithelium was lower in patients with active CD compared with control patients. In vitro, elafin significantly slowed the kinetics of the deamidation of the 33-mer peptide to its more immunogenic form. Treatment of gluten-sensitive mice with elafin delivered by the L. lactis vector normalized inflammation, improved permeability, and maintained ZO-1 expression.

Conclusions: The decreased elafin expression in the small intestine of patients with active CD, the reduction of 33-mer peptide deamidation by elafin, coupled to the barrier enhancing and anti-inflammatory effects observed in gluten-sensitive mice, suggest that this molecule may have pathophysiological and therapeutic importance in gluten-related disorders.
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http://dx.doi.org/10.1038/ajg.2014.48DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4219532PMC
May 2014

Differential induction of antimicrobial REGIII by the intestinal microbiota and Bifidobacterium breve NCC2950.

Appl Environ Microbiol 2013 Dec 4;79(24):7745-54. Epub 2013 Oct 4.

Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada.

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.
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http://dx.doi.org/10.1128/AEM.02470-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3837813PMC
December 2013

The copolymer P(HEMA-co-SS) binds gluten and reduces immune response in gluten-sensitized mice and human tissues.

Gastroenterology 2012 Feb 10;142(2):316-25.e1-12. Epub 2011 Nov 10.

Faculty of Pharmacy, Université de Montréal, Montréal, Quebec, Canada.

Background & Aims: Copolymers of hydroxyethyl methacrylate and styrene sulfonate complex with isolated gliadin (the toxic fraction of gluten) and prevent damage to the intestinal barrier in HLA-HCD4/DQ8 mice. We studied the activity toward gluten and hordein digestion and biologic effects of poly(hydroxyethyl methacrylate-co-styrene sulfonate (P(HEMA-co-SS)). We also investigated the effect of gliadin complex formation in intestinal biopsy specimens from patients with celiac disease.

Methods: We studied the ability of P(HEMA-co-SS) to reduce digestion of wheat gluten and barley hordein into immunotoxic peptides using liquid chromatography-mass spectrometry. The biodistribution and pharmacokinetic profile of orally administered P(HEMA-co-SS) was established in rodents using tritium-labeled polymer. We assessed the capacity of P(HEMA-co-SS) to prevent the immunologic and intestinal effects induced by a gluten-food mixture in gluten-sensitized HLA-HCD4/DQ8 mice after short-term and long-term administration. We measured the effects of gliadin complex formation on cytokine release ex vivo using intestinal biopsy specimens from patients with celiac disease.

Results: P(HEMA-co-SS) reduced digestion of wheat gluten and barley hordein in vitro, thereby decreasing formation of toxic peptides associated with celiac disease. After oral administration to rodents, P(HEMA-co-SS) was predominantly excreted in feces, even in the presence of low-grade mucosal inflammation and increased intestinal permeability. In gluten-sensitized mice, P(HEMA-co-SS) reduced paracellular permeability, normalized anti-gliadin immunoglobulin A in intestinal washes, and modulated the systemic immune response to gluten in a food mixture. Furthermore, incubation of P(HEMA-co-SS) with mucosal biopsy specimens from patients with celiac disease showed that secretion of tumor necrosis factor-α was reduced in the presence of partially digested gliadin.

Conclusions: The copolymer P(HEMA-co-SS) reduced digestion of wheat gluten and barley hordein and attenuated the immune response to gluten in a food mixture in rodents. It might be developed to prevent or reduce gluten-induced disorders in humans.
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http://dx.doi.org/10.1053/j.gastro.2011.10.038DOI Listing
February 2012

Sensitization to gliadin induces moderate enteropathy and insulitis in nonobese diabetic-DQ8 mice.

J Immunol 2011 Oct 12;187(8):4338-46. Epub 2011 Sep 12.

Farncombe Family Digestive Health Research Institute, McMaster University Medical Centre, Hamilton, Ontario L8N 3Z5, Canada.

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.
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http://dx.doi.org/10.4049/jimmunol.1100854DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3493154PMC
October 2011
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