Charlotte R. Hedin

Evidence for the use of probiotics and prebiotics in inflammatory bowel disease: a review of clinical trials.

Human subjects and their enteric microbiota have evolved together to reach a state of mutual tolerance. Mounting evidence from both animal models and human studies suggests that inflammatory bowel disease (IBD) represents a malfunction of this relationship. The enteric microecology therefore represents an attractive therapeutic target with few side effects. Probiotics and prebiotics have been investigated in clinical trials as treatments for IBD, with conflicting results. The evidence for the use of probiotics in the management of pouchitis is persuasive and several studies indicate their effectiveness in ulcerative colitis. Trials of probiotics and prebiotics in Crohns disease are less convincing. However, methodologies vary widely and a range of probiotic, prebiotic and combination (synbiotic) treatments have been tested in a variety of patient groups with an assortment of end points. Conclusions about any one treatment in a specific patient group can therefore only be drawn on evidence from relatively small numbers of patients. The present article reviews the role of the intestinal microbiota in the pathogenesis of IBD and addresses the clinical evidence for the therapeutic manipulation of bowel microbiota using probiotics, prebiotics and synbiotics in IBD.

Randomised, double-blind, placebo-controlled trial of fructo-oligosaccharides in active Crohn's disease

Introduction The commensal intestinal microbiota drive the inflammation associated with Crohns disease. However, bacteria such as bifidobacteria and Faecalibacterium prausnitzii appear to be immunoregulatory. In healthy subjects the intestinal microbiota are influenced by prebiotic carbohydrates such as fructo-oligosaccharides (FOS). Preliminary data suggest that FOS increase faecal bifidobacteria, induce immunoregulatory dendritic cell (DC) responses and reduce disease activity in patients with Crohns disease. Aims and methods To assess the impact of FOS in patients with active Crohns disease using an adequately powered randomised double-blind placebo-controlled trial with predefined clinical, microbiological and immunological end points. Patients with active Crohns disease were randomised to 15 g/day FOS or non-prebiotic placebo for 4 weeks. The primary end point was clinical response at week 4 (fall in Crohns Disease Activity Index of ≥70 points) in the intention-to-treat (ITT) population. Results 103 patients were randomised to receive FOS (n=54) or placebo (n=49). More patients receiving FOS (14 (26%) vs 4 (8%); p=0.018) withdrew before the 4-week end point. There was no significant difference in the number of patients achieving a clinical response between the FOS and placebo groups in the ITT analysis (12 (22%) vs 19 (39%), p=0.067). Patients receiving FOS had reduced proportions of interleukin (IL)-6-positive lamina propria DC and increased DC staining of IL-10 (p<0.05) but no change in IL-12p40 production. There were no significant differences in the faecal concentration of bifidobacteria and F prausnitzii between the groups at baseline or after the 4-week intervention. Conclusion An adequately powered placebo-controlled trial of FOS showed no clinical benefit in patients with active Crohns disease, despite impacting on DC function. ISRCTN50422530.

Smokers with active Crohn's disease have a clinically relevant dysbiosis of the gastrointestinal microbiota

Background: Patients with Crohns disease (CD) have an intestinal dysbiosis with components of the microbiota exerting differential immune effects. Smoking is associated with an increased incidence of CD, more frequent relapse, and greater burden of surgery. This study aimed to investigate the association between smoking and the intestinal microbiota in patients with active CD. Methods: Patients with active CD (n = 103) and healthy controls (n = 66) were recruited and demographic and clinical data recorded including current smoking behavior. Fecal samples were collected and analyzed by fluorescent in situ hybridization using probes targeting 16S rRNA of bacteria previously shown to be altered in active CD (bifidobacteria, bacteroides, Clostridium coccoides‐Eubacterium rectale, Escherichia coli, and Faecalibacterium prausnitzii). Results: In total, 29/101 (29%) patients with CD and 8/58 (14%) controls were current smokers (P = 0.032). Following multivariate analysis, smoking was found to have a significant and independent effect on the microbiota of patients with CD, with higher Bacteroides‐Prevotella in smokers (38.4%) compared with nonsmokers (28.1%) (F(1,93) = 12.6, P = 0.001). Healthy controls who smoked also had higher Bacteroides‐Prevotella (34.8%) than nonsmokers (24.1%) (F(1,55) = 4.5, P = 0.038). In the pooled multivariate analysis, patients with CD had higher bifidobacteria (F(1,156) = 30.5, P < 0.001), higher Bacteroides‐Prevotella (F(1,156) = 6.5, P = 0.012), and lower F. prausnitzii (F(1,156) = 3.8, P = 0.052) compared with healthy controls. Conclusions: Smokers have luminal microbiota that consist of significantly higher bacteroides. Investigation of whether this is one mechanism through which the negative effects of smoking on CD are mediated is warranted. (Inflamm Bowel Dis 2012;)

Relationship Between Human Intestinal Dendritic Cells, Gut Microbiota, and Disease Activity in Crohn's Disease

Background: Altered intestinal dendritic cell (DC) function underlies dysregulated T‐cell responses to bacteria in Crohns disease (CD) but it is unclear whether composition of the intestinal microbiota impacts local DC function. We assessed the relationship between DC function with disease activity and intestinal microbiota in patients with CD. Methods: Surface expression of Toll‐like receptor (TLR)‐2, TLR‐4, and spontaneous intracellular interleukin (IL)‐10, IL‐12p40, IL‐6 production by freshly isolated DC were analyzed by multicolor flow cytometry of cells extracted from rectal tissue of 10 controls and 28 CD patients. Myeloid DC were identified as CD11c+HLA‐DR+lin‐/dim cells (lin = anti‐CD3, CD14, CD16, CD19, CD34). Intestinal microbiota were analyzed by fluorescent in situ hybridization of fecal samples with oligonucleotide probes targeting 16S rRNA of bifidobacteria, bacteroides‐prevotella, C. coccoides‐E. rectale, and Faecalibacterium prausnitzii. Results: DC from CD produced higher amounts of IL‐12p40 and IL‐6 than control DC. IL‐6+ DC were associated with the CD Activity Index (r = 0.425; P = 0.024) and serum C‐reactive protein (CRP) (r = 0.643; P = 0.004). DC expression of TLR‐4 correlated with disease activity. IL‐12p40+ DC correlated with ratio of bacteroides: bifidobacteria (r = 0.535, P = 0.003). IL‐10+ DC correlated with bifidobacteria, and IL‐6+ DC correlated negatively with F. prausnitzii (r = −0.50; P = 0.008). The amount of TLR‐4 on DC correlated negatively with the concentration of F. prausnitzii. Conclusions: IL‐6 production by intestinal DC is increased in CD and correlates with disease activity and CRP. Bacterially driven local IL‐6 production by intestinal DC may overcome regulatory activity, resulting in unopposed effector function and tissue damage. Intestinal DC function may be influenced by the composition of the commensal microbiota. (Inflamm Bowel Dis 2011;)

Altered intestinal microbiota and blood T cell phenotype are shared by patients with Crohn's disease and their unaffected siblings

Objective Crohns disease (CD) is associated with intestinal dysbiosis, altered blood T cell populations, elevated faecal calprotectin (FC) and increased intestinal permeability (IP). CD-associated features present in siblings (increased risk of CD) but not in healthy controls, provide insight into early CD pathogenesis. We aimed to (1) Delineate the genetic, immune and microbiological profile of patients with CD, their siblings and controls and (2) Determine which factors discriminate between groups. Design Faecal microbiology was analysed by quantitative PCR targeting 16S ribosomal RNA, FC by ELISA, blood T cell phenotype by flow cytometry and IP by differential lactulose-rhamnose absorption in 22 patients with inactive CD, 21 of their healthy siblings and 25 controls. Subjects genotype relative risk was determined by Illumina Immuno BeadChip. Results Strikingly, siblings shared aspects of intestinal dysbiosis with patients with CD (lower concentrations of Faecalibacterium prausnitzii (p=0.048), Clostridia cluster IV (p=0.003) and Roseburia spp. (p=0.09) compared with controls). As in CD, siblings demonstrated a predominance of memory T cells (p=0.002) and elevated naïve CD4 T cell β7 integrin expression (p=0.01) compared with controls. FC was elevated (>50 μg/g) in 8/21 (38%) siblings compared with 2/25 (8%) controls (p=0.028); whereas IP did not differ between siblings and controls. Discriminant function analysis determined that combinations of these factors significantly discriminated between groups (χ2=80.4, df=20, p<0.001). Siblings were separated from controls by immunological and microbiological variables. Conclusions Healthy siblings of patients with CD manifest immune and microbiological abnormalities associated with CD distinct from their genotype-related risk and provide an excellent model in which to investigate early CD pathogenesis.

Adolescents with IBD: The importance of structured transition care

Children and adolescents with inflammatory bowel disease (IBD) tend to have more extensive and severe disease than adults. IBD presenting in childhood interferes with growth, education and employment as well as psychosocial and sexual development, frequently delaying adolescent developmental milestones. Transition, in the context of healthcare, is the purposeful, planned movement of adolescents and young adults with chronic physical and medical conditions to adult-orientated healthcare systems. Although no single model has been widely adopted and despite a paucity of data, recent guidelines from Europe and the USA propose the formation of specialist transition clinics for adolescent patients with IBD. In order to develop a successful transition service, the barriers that arise because of differences between paediatric and adult IBD services need to be identified. In this article, we review the concept of transitional care for adolescents with IBD, highlighting the important differences in not only, paediatric and adult IBD, but also paediatric and adult IBD services. We consider the consequences of failed transition, and describe the limited published data reporting different approaches to transition in IBD, before outlining our own approach.

Probiotic and prebiotic use in patients with inflammatory bowel disease: A case‐control study

Background: The use of complementary and alternative medicine in inflammatory bowel disease (IBD) has been extensively studied. However, the use of probiotics and prebiotics is poorly documented, despite evidence of efficacy of particular probiotic strains in specific forms of IBD. Methods: A case‐control study comprising interviewer‐administered questionnaires was conducted in IBD patients and healthy controls. Data regarding use and knowledge of probiotics and prebiotics, demographic, and clinical information were collected. Results: In total, 334 participants (234 IBD, 100 controls) were interviewed. Significantly more IBD patients than controls had ever used probiotics to manage their health (Crohns disease [CD] 43%, ulcerative colitis [UC] 51%, controls 21%, P < 0.001). Prebiotic use was negligible. On logistic regression analysis, having UC (odds ratio [OR] 4.30, 95% confidence interval [CI] 2.27–8.12) or CD (OR 3.05, 95% CI 1.66–5.60) were the strongest predictors of probiotic use. Within IBD patients the strongest predictor of probiotic use was current steroid use (OR 2.4, 95% CI 1.11–5.18). IBD patients had greater probiotic knowledge scores than controls (P = 0.003), although 20% of IBD probiotic users could not provide a definition of a probiotic. Less than half of IBD probiotic users discussed probiotic use with healthcare professionals, with commercial advertising being the primary source of information. Conclusions: Patients with IBD use probiotics to manage their health but frequently choose strains without evidence of efficacy in IBD. Patients rely on nonclinical sources of information and often do not disclose probiotic use to healthcare professionals. Conventional healthcare providers should inquire about probiotic use among their patients and offer evidence‐based advice. (Inflamm Bowel Dis 2010)

Family studies in Crohn's disease: new horizons in understanding disease pathogenesis, risk and prevention

Crohns disease (CD) is an incurable intestinal disorder in which the loss of immune tolerance to the commensal gut microbiota leads to chronic inflammation. The reason this occurs in specific individuals is unclear; however, a genetic predisposition is fundamental and relatives of patients with CD are at significant risk of developing the disease. Knowledge relating to the genetic loci that predispose to CD is accumulating, which raises the possibility of disease prediction and prevention in susceptible populations. However, the genetic basis of CD is complex and genotyping alone is likely to be insufficient to predict disease risk accurately. Specific physiological abnormalities associated with CD, such as increased intestinal permeability and raised faecal calprotectin, are also abnormal in some relatives of patients with CD. The combination of genotypic factors and biomarkers of risk makes the development of models of disease prediction a realistic possibility. Furthermore, enhanced understanding of the genotype and phenotype of the at-risk state in relatives of patients with CD allows the earliest stages in the pathogenesis of CD to be investigated and may allow intervention to prevent disease onset. This article reviews current knowledge of the at-risk phenotype in relatives of patients with CD and focuses on the implications for the design of future studies.

Siblings of patients with Crohn’s disease exhibit a biologically relevant dysbiosis in mucosal microbial metacommunities

Objective To determine the existence of mucosal dysbiosis in siblings of patients with Crohns disease (CD) using 454 pyrosequencing and to comprehensively characterise and determine the influence of genotypical and phenotypical factors, on that dysbiosis. Siblings of patients with CD have elevated risk of developing CD and display aspects of disease phenotype, including faecal dysbiosis. Whether the mucosal microbiota is disrupted in these at-risk individuals is unknown. Design Rectal biopsy DNA was extracted from 21 patients with quiescent CD, 17 of their healthy siblings and 19 unrelated healthy controls. Mucosal microbiota was analysed by 16S rRNA gene pyrosequencing and were classified into core and rare species. Genotypical risk was determined using Illumina Immuno BeadChip, faecal calprotectin by ELISA and blood T-cell phenotype by flow cytometry. Results Core microbiota of both patients with CD and healthy siblings was significantly less diverse than controls. Metacommunity profiling (Bray–Curtis (SBC) index) showed the sibling core microbial composition to be more similar to CD (SBC=0.70) than to healthy controls, whereas the sibling rare microbiota was more similar to healthy controls (SBC=0.42). Faecalibacterium prausnitzii contributed most to core metacommunity dissimilarity both between siblings and controls, and between patients and controls. Phenotype/genotype markers of CD risk significantly influenced microbiota variation between and within groups, of which genotype had the largest effect. Conclusions Individuals with elevated CD-risk display mucosal dysbiosis characterised by reduced diversity of core microbiota and lower abundance of F. prausnitzii. This dysbiosis in healthy people at risk of CD implicates microbiological processes in CD pathogenesis.

Proinflammatory Vδ2+ T Cells Populate the Human Intestinal Mucosa and Enhance IFN-γ Production by Colonic αβ T Cells

In nonhuman primates, Vγ9Vδ2+ (Vδ2)T cells proliferate and accumulate in mucosal tissues following microbial activation. Human Vδ2T cells produce proinflammatory cytokines in response to bacterial species that colonize the gut, but the role played by Vδ2T cells in intestinal immunity is unknown. We hypothesized that circulating Vδ2T cells can populate the human intestine and contribute to mucosal inflammation. Cell suspensions prepared from peripheral blood and intestinal biopsies were stimulated with microbial phosphoantigen (1-hydroxy-2-methyl-2-buten-4-yl 4-diphosphate [HDMAPP]) and analyzed by flow cytometry to determine Vδ2T cell phenotype, cytokine production, and proliferative potential. Circulating Vδ2T cells expressed gut-homing integrin α4β7 (>70%), which was coexpressed with skin-associated cutaneous leukocyte Ag by up to 15% of the total population. However, Vδ2T cell activation with HDMAPP and exposure to retinoic acid (signaling via retinoic acid receptor α) increased α4β7 expression and enhanced binding to mucosal addressin cell adhesion molecule-1 in vitro while simultaneously suppressing cutaneous leukocyte Ag, thereby generating a committed gut-tropic phenotype. Confocal microscopy and flow cytometry identified frequent Vδ2T cells that migrated out of human intestinal biopsies and comprised both CD103+ and CD103− subsets that produced TNF-α and IFN-γ upon phosphoantigen exposure, with more frequent cytokine-producing cells in the CD103− population. Activated intestinal Vδ2T cells expressed CD70 and HLA-DR but were unable to drive the proliferation of allogeneic naive CD4+ T cells. Instead, phosphoantigen-activated CD103− Vδ2T cells increased T-bet expression and enhanced IFN-γ production by autologous colonic αβ T cells via an IFN-γ–dependent mechanism. These data demonstrate that circulating Vδ2T cells display enhanced gut-homing potential upon microbial activation and populate the human intestinal mucosa, generating functionally distinct CD103+ and CD103− subsets that can promote inflammation by colonic αβ T cells.