Aine Fanning

Functional modulation of human intestinal epithelial cell responses by Bifidobacterium infantis and Lactobacillus salivarius

Intestinal epithelial cells (IECs) and dendritic cells (DCs) play a pivotal role in antigen sampling and the maintenance of gut homeostasis. However, the interaction of commensal bacteria with the intestinal surface remains incompletely understood. Here we investigated immune cell responses to commensal and pathogenic bacteria. HT‐29 human IECs were incubated with Bifidobacterium infantis 35624, Lactobacillus salivarius UCC118 or Salmonella typhimurium UK1 for varying times, or were pretreated with a probiotic for 2 hr prior to stimulation with S. typhimurium or flagellin. Gene arrays were used to examine inflammatory gene expression. Nuclear factor (NF)‐κB activation, interleukin (IL)‐8 secretion, pathogen adherence to IECs, and mucin‐3 (MUC3) and E‐cadherin gene expression were assayed by TransAM assay, enzyme‐linked immunosorbent assay (ELISA), fluorescence, and real‐time reverse transcriptase–polymerase chain reaction (RT‐PCR), respectively. IL‐10 and tumour necrosis factor (TNF)‐α secretion by bacteria‐treated peripheral blood‐derived DCs were measured using ELISA. S. typhimurium increased expression of 36 of the 847 immune‐related genes assayed, including NF‐κB and IL‐8. The commensal bacteria did not alter expression levels of any of the 847 genes. However, B. infantis and L. salivarius attenuated both IL‐8 secretion at baseline and S. typhimurium‐induced pro‐inflammatory responses. B. infantis also limited flagellin‐induced IL‐8 protein secretion. The commensal bacteria did not increase MUC3or E‐cadherin expression, or interfere with pathogen binding to HT‐29 cells, but they did stimulate IL‐10 and TNF‐α secretion by DCs. The data demonstrate that, although the intestinal epithelium is immunologically quiescent when it encounters B. infantis or L. salivarius, these commensal bacteria exert immunomodulatory effects on intestinal immune cells that mediate host responses to flagellin and enteric pathogens.

Differential expression of toll-like receptors in patients with irritable bowel syndrome.

OBJECTIVES:The pathogenesis of irritable bowel syndrome (IBS) is poorly understood. One contributory factor may be low-grade mucosal inflammation, perhaps initiated by the microbiota. Toll-like receptors (TLRs) are a family of pathogen-recognition receptors of the innate immune system. The aim of this study was to evaluate the potential involvement of TLRs in IBS to further understand the involvement of the innate immune system in this complex disorder.METHODS:The expression of TLRs was investigated in colonic biopsy samples obtained from 26 IBS patients and compared with 19 healthy controls. Protein expression of TLR4, TLR7, and TLR8 was confirmed by immunofluorescence and alterations in the TLR4 protein were confirmed by western blot.RESULTS:Quantitative reverse transcriptase-PCR showed increased levels of TLR4 (P≤0.001) and TLR5 (P=0.0013) and decreased levels of TLR7 (P≤0.001) and TLR8 (P=0.0019) in IBS patients.CONCLUSIONS:Our results support the presence of an immune engagement between the microbiota and the host in IBS; an interaction that involves innate immunity and could generate a low-grade inflammatory response. These findings could also offer an additional biomarker of the disease or a disease subset.

Mucosal cytokine imbalance in irritable bowel syndrome

Objective. To systematically examine mucosal biopsies for differences in cytokine gene expression and protein secretion. Material and methods. The study included 59 females with irritable bowel syndrome (IBS) and 39, otherwise healthy, female volunteers presenting for colonoscopy. Colonic biopsies from subsets were studied by microarray analysis (IBS, n=9; controls, n=8), quantitative reverse transcription-polymerase chain reaction (qRT-PCR) (IBS, n=22; controls, n=21), and ex vivo biopsy culture (IBS, n=28, controls, n=10). Biopsies from patients with active colitis were used as inflammatory disease controls. Results. While gene array analysis revealed extensive overlapping between controls and IBS patients, reduced expression of genes linked to chemokine function was evident among the IBS patients alone. Differential expression was confirmed by qRT-PCR or ex vivo biopsy culture for 5 out of 6 selected genes. Reduced secretion of chemokines (IL-8, CXCL-9 and MCP-1) but not pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) was established on the basis of the ex vivo biopsy cultures. These findings were in marked contrast to the IBD patients who demonstrated increased production of both chemokines and pro-inflammatory cytokines. Conclusions. Despite the expected heterogeneity of the disorder, differences in mucosal chemokine signalling were evident in this cross-sectional study of IBS patients at the level of both gene expression and protein secretion, with IBS patients demonstrating a consistent deficit in the expression and secretion of chemokines known to play a critical role in mucosal defence.

Modulation of pathogen-induced CCL20 secretion from HT-29 human intestinal epithelial cells by commensal bacteria

BackgroundHuman intestinal epithelial cells (IECs) secrete the chemokine CCL20 in response to infection by various enteropathogenic bacteria or exposure to bacterial flagellin. CCL20 recruits immature dendritic cells and lymphocytes to target sites. Here we investigated IEC responses to various pathogenic and commensal bacteria as well as the modulatory effects of commensal bacteria on pathogen-induced CCL20 secretion. HT-29 human IECs were incubated with commensal bacteria (Bifidobacterium infantis or Lactobacillus salivarius), or with Salmonella typhimurium, its flagellin, Clostridium difficile, Mycobacterium paratuberculosis, or Mycobacterium smegmatis for varying times. In some studies, HT-29 cells were pre-treated with a commensal strain for 2 hr prior to infection or flagellin stimulation. CCL20 and interleukin (IL)-8 secretion and nuclear factor (NF)-κB activation were measured using enzyme-linked immunosorbent assays.ResultsCompared to untreated cells, S. typhimurium, C. difficile, M. paratuberculosis, and flagellin activated NF-κB and stimulated significant secretion of CCL20 and IL-8 by HT-29 cells. Conversely, B. infantis, L. salivarius or M. smegmatis did not activate NF-κB or augment CCL20 or IL-8 production. Treatment with B. infantis, but not L. salivarius, dose-dependently inhibited the baseline secretion of CCL20. In cells pre-treated with B. infantis, C. difficile-, S. typhimurium-, and flagellin-induced CCL20 were significantly attenuated. B. infantis did not limit M. Paratuberculosis- induced CCL20 secretion.ConclusionThis study is the first to demonstrate that a commensal strain can attenuate CCL20 secretion in HT-29 IECs. Collectively, the data indicate that M. paratuberculosis may mediate mucosal damage and that B. infantis can exert immunomodulatory effects on IECs that mediate host responses to flagellin and flagellated enteric pathogens.

Down‐regulation of p38 mitogen‐activated protein kinase activation and proinflammatory cytokine production by mitogen‐activated protein kinase inhibitors in inflammatory bowel disease

Crohns disease and ulcerative colitis are inflammatory bowel diseases (IBD) characterized by chronic relapsing mucosal inflammation. Tumour necrosis factor (TNF)‐α, a known agonist of the mitogen‐activated protein kinase (MAPK) pathway, is a key cytokine in this process. We aimed first to determine whether p38 MAPK is activated in IBD inflamed mucosa, and then studied the effect of four different p38α inhibitory compounds on MAPK phosphorylation and secretion of proinflammatory cytokines by IBD lamina propria mononuclear cells (LPMCs) and organ culture biopsies. In vivo phospho‐p38α and p38α expression was evaluated by immunoblotting on intestinal biopsies from inflamed areas of patients affected by Crohns disease and ulcerative colitis, and from normal mucosa of sex‐ and age‐matched control subjects. Both mucosal biopsies and isolated LPMCs were incubated with four different p38α selective inhibitory drugs. TNF‐α, interleukin (IL)‐1β and IL‐6 were measured in the organ and cell culture supernatants by enzyme‐linked immunosorbent assay. We found higher levels of phospho‐p38α in the inflamed mucosa of IBD patients in comparison to controls. All the p38α inhibitory drugs inhibited p38α phosphorylation and secretion of TNF‐α, IL‐1β and IL‐6 from IBD LPMCs and biopsies. Activated p38α MAPK is up‐regulated in the inflamed mucosa of patients with IBD. Additionally, all the p38α selective inhibitory drugs significantly down‐regulated the activation of the MAPK pathway and the secretion of proinflammatory cytokines.

Differential expression of key regulators of Toll-like receptors in ulcerative colitis and Crohn's disease: a role for Tollip and peroxisome proliferator-activated receptor gamma?

The innate immune system is currently seen as the probable initiator of events which culminate in the development of inflammatory bowel disease (IBD) with Toll‐like receptors (TLRs) known to be involved in this disease process. Many regulators of TLRs have been described, and dysregulation of these may also be important in the pathogenesis of IBD. The aim of this study was to perform a co‐ordinated analysis of the expression levels of both key intestinal TLRs and their inhibitory proteins in the same IBD cohorts, both ulcerative colitis (UC) and Crohns disease (CD), in order to evaluate the potential roles of these proteins in the pathogenesis of IBD. Of the six TLRs (TLRs 1, 2, 4, 5, 6 and 9) examined, only TLR‐4 was increased significantly in IBD, specifically in active UC. In contrast, differential alterations in expression of TLR inhibitory proteins were observed. A20 and suppressor of cytokine signalling 1 (SOCS1) were increased only in active UC while interleukin‐1 receptor‐associated kinase 1 (IRAK‐m) and B cell lymphoma 3 protein (Bcl‐3) were increased in both active UC and CD. In contrast, expression of both peroxisome proliferator‐activated receptor gamma (PPARγ) and Toll interacting protein (Tollip) was decreased in both active and inactive UC and CD and at both mRNA and protein levels. In addition, expression of both PPARγ and A20 expression was increased by stimulation of a colonic epithelial cell line Caco‐2 with both TLR ligands and commensal bacterial strains. These data suggest that IBD may be associated with distinctive changes in TLR‐4 and TLR inhibitory proteins, implying that alterations in these may contribute to the pathogenesis of IBD.

Differential expression of key regulators of Toll‐like Receptors in Ulcerative Colitis and Crohn's disease: A role for Tollip and PPARγ?

The innate immune system is currently seen as the probable initiator of events which culminate in the development of inflammatory bowel disease (IBD) with Toll‐like receptors (TLRs) known to be involved in this disease process. Many regulators of TLRs have been described, and dysregulation of these may also be important in the pathogenesis of IBD. The aim of this study was to perform a co‐ordinated analysis of the expression levels of both key intestinal TLRs and their inhibitory proteins in the same IBD cohorts, both ulcerative colitis (UC) and Crohns disease (CD), in order to evaluate the potential roles of these proteins in the pathogenesis of IBD. Of the six TLRs (TLRs 1, 2, 4, 5, 6 and 9) examined, only TLR‐4 was increased significantly in IBD, specifically in active UC. In contrast, differential alterations in expression of TLR inhibitory proteins were observed. A20 and suppressor of cytokine signalling 1 (SOCS1) were increased only in active UC while interleukin‐1 receptor‐associated kinase 1 (IRAK‐m) and B cell lymphoma 3 protein (Bcl‐3) were increased in both active UC and CD. In contrast, expression of both peroxisome proliferator‐activated receptor gamma (PPARγ) and Toll interacting protein (Tollip) was decreased in both active and inactive UC and CD and at both mRNA and protein levels. In addition, expression of both PPARγ and A20 expression was increased by stimulation of a colonic epithelial cell line Caco‐2 with both TLR ligands and commensal bacterial strains. These data suggest that IBD may be associated with distinctive changes in TLR‐4 and TLR inhibitory proteins, implying that alterations in these may contribute to the pathogenesis of IBD.

A Prospective Metagenomic and Metabolomic Analysis of the Impact of Exercise and/or Whey Protein Supplementation on the Gut Microbiome of Sedentary Adults

The gut microbiota of humans is a critical component of functional development and subsequent health. It is important to understand the lifestyle and dietary factors that affect the gut microbiome and what impact these factors may have. Animal studies suggest that exercise can directly affect the gut microbiota, and elite athletes demonstrate unique beneficial and diverse gut microbiome characteristics. These characteristics are associated with levels of protein consumption and levels of physical activity. The results of this study show that increasing the fitness levels of physically inactive humans leads to modest but detectable changes in gut microbiota characteristics. For the first time, we show that regular whey protein intake leads to significant alterations to the composition of the gut virome. ABSTRACT Many components of modern living exert influence on the resident intestinal microbiota of humans with resultant impact on host health. For example, exercise-associated changes in the diversity, composition, and functional profiles of microbial populations in the gut have been described in cross-sectional studies of habitual athletes. However, this relationship is also affected by changes in diet, such as changes in dietary and supplementary protein consumption, that coincide with exercise. To determine whether increasing physical activity and/or increased protein intake modulates gut microbial composition and function, we prospectively challenged healthy but sedentary adults with a short-term exercise regime, with and without concurrent daily whey protein consumption. Metagenomics- and metabolomics-based assessments demonstrated modest changes in gut microbial composition and function following increases in physical activity. Significant changes in the diversity of the gut virome were evident in participants receiving daily whey protein supplementation. Results indicate that improved body composition with exercise is not dependent on major changes in the diversity of microbial populations in the gut. The diverse microbial characteristics previously observed in long-term habitual athletes may be a later response to exercise and fitness improvement. IMPORTANCE The gut microbiota of humans is a critical component of functional development and subsequent health. It is important to understand the lifestyle and dietary factors that affect the gut microbiome and what impact these factors may have. Animal studies suggest that exercise can directly affect the gut microbiota, and elite athletes demonstrate unique beneficial and diverse gut microbiome characteristics. These characteristics are associated with levels of protein consumption and levels of physical activity. The results of this study show that increasing the fitness levels of physically inactive humans leads to modest but detectable changes in gut microbiota characteristics. For the first time, we show that regular whey protein intake leads to significant alterations to the composition of the gut virome.

Pregnancy-specific glycoprotein expression in normal gastrointestinal tract and in tumors detected with novel monoclonal antibodies

ABSTRACT Pregnancy-specific glycoproteins (PSGs) are immunoglobulin superfamily members related to the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family and are encoded by 10 genes in the human. They are secreted at high levels by placental syncytiotrophoblast into maternal blood during pregnancy, and are implicated in immunoregulation, thromboregulation, and angiogenesis. To determine whether PSGs are expressed in tumors, we characterized 16 novel monoclonal antibodies to human PSG1 and used 2 that do not cross-react with CEACAMs to study PSG expression in tumors and in the gastrointestinal (GI) tract using tissue arrays and immunohistochemistry. Staining was frequently observed in primary squamous cell carcinomas and colonic adenocarcinomas and was correlated with the degree of tumor differentiation, being largely absent from metastatic samples. Staining was also observed in normal oesophageal and colonic epithelium. PSG expression in the human and mouse GI tract was confirmed using quantitative RT-PCR. However, mRNA expression was several orders of magnitude lower in the GI tract compared to placenta. Our results identify a non-placental site of PSG expression in the gut and associated tumors, with implications for determining whether PSGs have a role in tumor progression, and utility as tumor biomarkers.

Mo1098 Differential Expression of Epigenetic Modifier Genes in Inflammatory Bowel Disease Colonic Tissue - PRDM1 and PRDM8 are up-Regulated in Active Ulcerative Colitis

and p<0.03 respectively) after SP treatment in UC-derivedmesenteric preadipocytes. Furthermore, SP induced activation of both p38MAPK and ERK1/2 in UC-derived preadipocytes, in contrast to control preadipocytes where activation of these kinases was either reduced (ERK) or unaffected (p38). Conclusions: Our data suggest a distinct disease-dependent proinflammatory effect of SP on preadipocytes, which may be due to the different expression levels of NK1R and/or altered state of downstream regulatory pathways. Our preliminary evidence suggests a potential role for p38 MAPK and ERK1/2 signaling pathways in the regulation of differential cytokine responses between control and UC-derived preadipocytes. Support: NIH RC1DK086150, RO1DK47343, and the Broad Medical Foundation (BMRP)