J. Landy

Review article: faecal transplantation therapy for gastrointestinal disease.

Aliment Pharmacol Ther 2011; 34: 409–415

Intestinal dendritic cells: Their role in intestinal inflammation, manipulation by the gut microbiota and differences between mice and men

The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance of the commensal microbiota and food antigens. Dendritic cells (DC) generate primary T-cell responses, and determine whether these responses are immunogenic or tolerogenic. The regulatory role of DC is of particular importance in the gut due to the high antigenic load. Intestinal DC act as sentinels, sampling potentially pathogenic antigens but also harmless antigens including the commensal microbiota. Following antigen acquisition, intestinal DC migrate to secondary lymphoid organs to activate naive T-cells. DC also imprint specific homing properties on T-cells that they stimulate; gut DC specifically induce gut-homing properties on T-cells upon activation, enabling T-cell migration back to intestinal sites. Data regarding properties on gut DC in humans is scarce, although evidence now supports the role of DC as important players in intestinal immunity in humans. Here, we review the role of intestinal DC in shaping mucosal immune responses and directing tissue-specific T-cell responses, with a special focus on the importance of distinguishing DC subsets from macrophages at intestinal sites. We compare and contrast human DC with their murine counterparts, and discuss the ability of the gut microbiota to shape intestinal DC function, and how this may be dysregulated in inflammatory bowel disease (IBD). Lastly, we describe recent advances in the study of probiotics on intestinal DC function, including the use of soluble secreted bacterial products.

Tight junctions in inflammatory bowel diseases and inflammatory bowel disease associated colorectal cancer

Inflammatory bowel diseases are characterised by inflammation that compromises the integrity of the epithelial barrier. The intestinal epithelium is not only a static barrier but has evolved complex mechanisms to control and regulate bacterial interactions with the mucosal surface. Apical tight junction proteins are critical in the maintenance of epithelial barrier function and control of paracellular permeability. The characterisation of alterations in tight junction proteins as key players in epithelial barrier function in inflammatory bowel diseases is rapidly enhancing our understanding of critical mechanisms in disease pathogenesis as well as novel therapeutic opportunities. Here we give an overview of recent literature focusing on the role of tight junction proteins, in particular claudins, in inflammatory bowel diseases and inflammatory bowel disease associated colorectal cancer.

Altered human gut dendritic cell properties in ulcerative colitis are reversed by Lactobacillus plantarum extracellular encrypted peptide STp

SCOPE The human/microbiota cross-talk is partially mediated by bacteria-derived peptides like Serine-Threonine peptide (STp), which is resistant to gut proteolysis, is found in the human healthy colon and induces regulatory properties on gut dendritic cells (DCs); here we characterized human gut DC in ulcerative colitis (UC) patients and studied the effect of STp on their properties. METHODS AND RESULTS Human colonic DC from healthy controls and UC patients were isolated, conditioned for 24 h +/- STp and characterized by flow cytometry, immunohistochemistry, and electron microscopy. Expression of immature DC markers DC-SIGN and ILT3, and Toll-like receptors were increased on gut UC-DC. Langerin (involved in phagocytosis), lymph node homing marker CCR7, and activation markers CD40/CD80/CD86 were decreased in UC. Gut DC had restricted stimulatory capacity for T-cells in UC. Conditioning of DC with STp in vitro reduced Toll-like receptor expression, increased CD40 and CD80 expression, and restored their stimulatory capacity. CONCLUSION Colonic DCs display an abnormal immature phenotype in UC, which was partially restored following STp treatment. Bacteria-derived metabolites, like STp, seem to have a role in gut homeostasis that is missing in UC so they might lead a new era of probiotic products setting the basis for nondrug dietary therapy in inflammatory bowel disease.

Etiology of pouchitis

Abstract: Restorative proctocolectomy with ileal‐pouch anal anastomosis (RPC) is the operation of choice for ulcerative colitis (UC) patients requiring surgery. It is also used for patients with familial adenomatous polyposis (FAP). Pouchitis accounts for 10% of pouch failures. It is an idiopathic inflammatory condition that may occur in up to 50% of patients after RPC for UC. It is rarely seen in FAP patients after RPC. The etiology of pouchitis remains unclear. An overlap with UC is suggested by the frequency with which pouchitis affects patients with UC compared with FAP patients. There is significant clinical evidence implicating bacteria in the pathogenesis of pouchitis. Studies using culture and molecular methods demonstrate a dysbiosis of the pouch microbiota in pouchitis. Risk factors, genetic associations, and serological markers of pouchitis suggest that the interactions between the host immune responses and the pouch microbiota underlie the etiology of this idiopathic inflammatory condition. Here we present a detailed review of the data focusing on the pouch microbiota and the immune responses that support this hypothesis. We also discuss the contribution of luminal metabolic factors and the epithelial membrane in the etiology of this inflammatory process. The ileoanal pouch offers a unique opportunity to study the inter‐relationships between the gut microbiota and host immune responses from before the onset of disease. For this reason the study of pouchitis could serve as a human model that significantly enhances our understanding of inflammatory bowel diseases in general. (Inflamm Bowel Dis 2012;)

Variable alterations of the microbiota, without metabolic or immunological change, following faecal microbiota transplantation in patients with chronic pouchitis

Faecal microbiota transplantation (FMT) is effective in the treatment of Clostridium difficile infection, where efficacy correlates with changes in microbiota diversity and composition. The effects of FMT on recipient microbiota in inflammatory bowel diseases (IBD) remain unclear. We assessed the effects of FMT on microbiota composition and function, mucosal immune response, and clinical outcome in patients with chronic pouchitis. Eight patients with chronic pouchitis (current PDAI ≥7) were treated with FMT via nasogastric administration. Clinical activity was assessed before and four weeks following FMT. Faecal coliform antibiotic sensitivities were analysed, and changes in pouch faecal and mucosal microbiota assessed by 16S rRNA gene pyrosequencing and 1H NMR spectroscopy. Lamina propria dendritic cell phenotype and cytokine profiles were assessed by flow cytometric analysis and multiplex assay. Following FMT, there were variable shifts in faecal and mucosal microbiota composition and, in some patients, changes in proportional abundance of species suggestive of a “healthier” pouch microbiota. However, there were no significant FMT-induced metabolic or immunological changes, or beneficial clinical response. Given the lack of clinical response following FMT via a single nasogastric administration our results suggest that FMT/bacteriotherapy for pouchitis patients requires further optimisation.

Skin‐ and gut‐homing molecules on human circulating γδ T cells and their dysregulation in inflammatory bowel disease

Changes in phenotype and function of γδ T cells have been reported in inflammatory bowel disease (IBD), including Crohns disease (CD) and ulcerative colitis (UC). Dysregulation of lymphocyte migration plays a key role in IBD pathogenesis; however, data on migratory properties of γδ T cells are scarce. Human circulating γδ T cells from healthy controls (n = 27), patients with active CD (n = 15), active UC (n = 14) or cutaneous manifestations of IBD (n = 2) were characterized by flow cytometry. Circulating γδ T cells in healthy controls were CD3hi and expressed CD45RO. They expressed gut‐homing molecule β7 but not gut‐homing molecule corresponding chemokine receptors (CCR)9, or skin‐homing molecules cutaneous lymphocyte‐associated antigen (CLA) and CCR4, despite conventional T cells containing populations expressing these molecules. CCR9 expression was increased on γδ T cells in CD and UC, while skin‐homing CLA was expressed aberrantly on γδ T cells in patients with cutaneous manifestations of IBD. Lower levels of CD3 expression were found on γδ T cells in CD but not in UC, and a lower proportion of γδ T cells expressed CD45RO in CD and UC. Enhanced expression of gut‐homing molecules on circulating γδ T cells in IBD and skin‐homing molecules in cutaneous manifestations of IBD may be of clinical relevance.

Oral tacrolimus as maintenance therapy for refractory ulcerative colitis—an analysis of outcomes in two London tertiary centres ☆

BACKGROUND The medical management of refractory ulcerative colitis (UC) remains a significant challenge. Two randomised controlled studies have demonstrated tacrolimus therapy is effective for the induction of remission of moderate to severe UC. However, the long term outcomes of UC patients treated with tacrolimus as maintenance therapy are not certain. AIMS This study aims to assess the efficacy of tacrolimus maintenance therapy for refractory UC. METHODS A retrospective review of patients with UC treated with tacrolimus at two London tertiary centres was performed. Clinical outcomes were assessed at six months, at the end of tacrolimus treatment, or at the last follow-up for patients continuing tacrolimus treatment. Modified Truelove-Witts score (mTW) and Mayo endoscopy subscores were calculated. RESULTS 25 patients with UC, treated with oral tacrolimus between 2005 and 2011, were identified. The median duration of tacrolimus treatment was 9 months (IQR 3.7-18.2 months). The median duration of follow-up was 27 months (range 3-66 months). At six months thirteen (52%) patients had achieved and maintained clinical response and eleven (44%) were in clinical remission. The mean mTW score decreased from 10+/-0.5 before therapy, to 5.8+/-0.8 (p≤0.001 95% CI 2.7-5.8) at cessation of treatment or last follow-up. Mayo endoscopy subscore decreased from 2.6+/-0.1 to 1.2+/-0.2 (p≤0.001 mean reduction 1.4, 95% CI 0.8-1.9). Eight patients (32%) subsequently underwent a colectomy within a mean time of 17 months (range 2-45 months). CONCLUSION Tacrolimus is effective for the maintenance of refractory UC and can deliver sustained improvement in mucosal inflammation.

Tu1985 A Prospective Controlled Pilot Study of Fecal Microbiota Transplantation for Chronic Refractory Pouchitis

Introduction Faecal microbiota transplantation (FMT) is an effective therapy for Clostridium difficile and possibly inflammatory bowel diseases (IBD). Published data of FMT for inflammatory bowel diseases are reported in case series and case reports. To our knowledge, there are no controlled studies of FMT for IBD. We aimed to conduct a prospective study of FMT for chronic refractory pouchitis. Methods Patients with clinically, endoscopically and histologically confirmed chronic refractory pouchitis; with a pouch disease activity index (PDAI) > 7 were included. Donors were screened by clinical history and serology for HAV, HBV, HCV, HEV, Treponema, HIV, HTLV I/II and stool for M, C+S, C. difficile toxin and parasites. Fresh donor stool was collected within six hours of nasogasric administration of FMT. Stool samples were also collected from patients for analysis of coliform sensitivities before and 4 weeks after FMT. PDAI and Cleveland global quality of life score (CGQoL ) were recorded prior to FMT and four weeks after FMT. Results Eight patients with chronic refractory pouchitis who had undergone restorative proctocolectomy for ulcerative colitis underwent FMT. Three patients had ESBL resistant coliforms on stool analysis prior toFMT. Two of these patients demonstrated a change to ciprofloxacin sensitive coliform following FMT. The mean PDAI prior to FMT was 12. The mean CGQoL was 0.45. At 4 weeks following FMT, no patient had achieved a clinical remission (mean PDAI 11). No improvement in CGQoL was seen (mean 0.44). Conclusion FMT via nasogastric administration was not effective in achieving clinical remission for chronic refractory pouchitis at 4 weeks after FMT. However, in two patients with ESBL resistant coliform, ciprofloxacin sensitivity was regained following FMT and these patients have subsequently been maintained on ciprofloxacin. This suggests FMT may alter the pouch microbiota. Further molecular microbiological analysis is being undertaken to determine the effect FMT had on these patients’ microbiota. In addition, further studies of FMT are required to assess the effect of different methods of FMT that may be more efficacious for this group of patients. Disclosure of Interest None Declared.

Lost therapeutic potential of monocyte‐derived dendritic cells through lost tissue homing: stable restoration of gut specificity with retinoic acid

Human monocyte‐derived dendritic cells (DC) (MoDC) are utilized for immunotherapy. However, in‐vitro immunological effects are often not mirrored in vivo. We studied the tissue‐homing potential of MoDC. Circulating monocytes and DC expressed different tissue‐homing markers and, during in‐vitro development of MoDC, homing marker expression was lost resulting in a ‘homeless’ phenotype. Retinoic acid (RA) induced gut‐homing markers (β7 and CCR9) and a regulatory phenotype and function [decreased human leucocyte antigen D‐related (HLA‐DR) and increased ILT3 and fluorescein isothiocyanate (FITC‐dextran uptake) in MoDC]. RA‐MoDC were less stimulatory and primed conditioned T cells with a gut‐homing profile (β7+CLA−). Unlike the normal intestinal microenvironment, that from inflamed colon of ulcerative colitis (UC) patients did not induce regulatory properties in MoDC. However, RA‐MoDC maintained their regulatory gut‐specific properties even in the presence of UC microenvironment. Therefore, MoDC may be ineffectual for immunotherapy because they lack tissue‐homing and tissue‐imprinting specificity. However, MoDC rehabilitation with gut‐homing potential by RA could be useful in promoting immunotherapy in pathologies such as UC.