Hafid O. Al-Hassi

Clinical, microbiological, and immunological effects of fructo-oligosaccharide in patients with Crohn’s disease

Background and aims: The intestinal microbiota play a pivotal role in the inflammation associated with Crohn’s disease through their interaction with the mucosal immune system. Some bifidobacteria species are immunoregulatory and induce increased dendritic cell interleukin 10 (IL-10) release in vitro. Fructo-oligosaccharides (FOS) increase faecal and mucosal bifidobacteria in healthy volunteers. The aim of this study was to assess the effect of FOS administration on disease activity, bifidobacteria concentrations, and mucosal dendritic cell function in patients with moderately active Crohn’s disease. Patients and methods: Ten patients with active ileocolonic Crohn’s disease received 15 g of FOS for three weeks. Disease activity was measured using the Harvey Bradshaw index. Faecal and mucosal bifidobacteria were quantified by fluorescence in situ hybridisation, and mucosal dendritic cell IL-10 and Toll-like receptor (TLR) expression were assessed by flow cytometry of dissociated rectal biopsies. Results: FOS induced a significant reduction in the Harvey Bradshaw index from 9.8 (SD 3.1) to 6.9 (3.4) (p<0.01). There was a significant increase in faecal bifidobacteria concentration from 8.8 (0.9) log10 to 9.4 (0.9) log10 cells/g dry faeces (p<0.001). The percentage of IL-10 positive dendritic cells increased from 30 (12)% to 53 (10)% (p = 0.06). Finally, the percentage of dendritic cells expressing TLR2 and TLR4 increased from 1.7 (1.7)% to 36.8 (15.9)% (p = 0.08) and from 3.6 (3.6)% to 75.4 (3.4)% (p<0.001), respectively. Conclusions: FOS supplementation increases faecal bifidobacteria concentrations and modifies mucosal dendritic cell function. This novel therapeutic strategy appears to decrease Crohn’s disease activity in a small open label trial and therefore warrants further investigation.

Review article: faecal transplantation therapy for gastrointestinal disease.

Aliment Pharmacol Ther 2011; 34: 409–415

Is right-sided colon cancer different to left-sided colorectal cancer? – A systematic review

Colorectal cancer (CRC) exhibits differences in incidence, pathogenesis, molecular pathways and outcome depending on the location of the tumor. This review focuses on the latest developments in epidemiological and scientific studies, which have enhanced our understanding on the underlying genetic and immunological differences between the proximal (right-sided) colon and the distal (left-sided) colorectum. The different ways in which environmental risk factors influence the pathogenesis of CRC depending on its location and the variations in surgical and oncological outcomes are also discussed in this review. In the current era of personalized medicine, we aim to reiterate the importance of tumor location in management of CRC and the implication on future clinical and scientific research.

Immunosuppressive effects via human intestinal dendritic cells of probiotic bacteria and steroids in the treatment of acute ulcerative colitis

Background: In ulcerative colitis (UC) gut bacteria drive inflammation. Bacterial recognition and T‐cell responses are shaped by intestinal dendritic cells (DCs); therapeutic effects of probiotic bacteria may relate to modulation of intestinal DC. The probiotic mixture, VSL#3, increases interleukin (IL)‐10 and downregulates IL‐12p40 production by DC in vitro. We evaluated in vivo effects of oral VSL#3 and steroids on colonic DC in patients with acute UC. Methods: Rectal biopsies were obtained from patients with active UC before and after treatment with VSL#3, corticosteroids, or placebo, and from healthy controls. Myeloid colonic DC were studied from freshly isolated lamina propria cells using multicolor flow cytometry. Surface expression of activation markers, CD40, CD86, pattern recognition receptors, Toll‐like receptor (TLR)‐2 and TLR‐4 were assessed. Changed function was measured from ongoing intracellular IL‐10, IL‐12p40, IL‐6, and IL‐13 production. Results: Acute UC colonic myeloid DC were producing more IL‐10 and IL‐12p40 than control DC (P = 0.01). In VSL#3‐treated patients DC TLR‐2 expression decreased (P < 0.05), IL‐10 production increased and IL‐12p40 production decreased (P < 0.005); 10/14 patients on VSL#3 showed a clinical response. Corticosteroids also resulted in increased IL‐10 and reduced IL‐12p40 production by DC. Conversely, in patients on placebo, TLR‐2 expression and intensity of staining for IL‐12p40 and IL‐6 increased (all P < 0.05); 5/14 patients on placebo showed a clinical response (P = NS). Conclusions: Despite small numbers of human colonic DC available, we showed that treatment of UC patients with probiotic VSL#3 and corticosteroids induced “favorable” intestinal DC function in vivo, increasing regulatory cytokines and lowering proinflammatory cytokines and TLR expression. These effects may contribute to therapeutic benefit. (Inflamm Bowel Dis 2010)

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.

Homing of immune cells: role in homeostasis and intestinal inflammation.

Abstract: Rather like a satellite navigation system directing a vehicle to a particular destination defined by post‐code, immune cells have homing molecules or “immune post‐codes” enabling them to be recruited to specific organs, such as the intestine or skin. An efficient system would be designed such that the site of entry of an antigen influences the homing of effector T cells back to the appropriate organ. For example, to mount an immune response against an intestinal pathogen, T cells with a propensity to home to the gut to clear the infection would be induced. In health, there is such a sophisticated and finely tuned system in operation, enabling an appropriate balance of immune activity in different anatomical compartments. In disease states such as inflammatory bowel disease (IBD), which is characterized by intestinal inflammation and often an inflammatory process involving other organs such as skin, joints, liver, and eye, there is accumulating evidence that there is malfunction of this immune cell trafficking system. The clinical importance of dysregulated immune cell trafficking in IBD is reflected in recently proven efficacious therapies that target trafficking pathways such as natalizumab, an &agr;4 integrin antibody, and Traficet‐EN, a chemokine receptor‐9 (CCR9) antagonist. Here we review the mechanisms involved in the homing of immune cells to different tissues, in particular the intestine, and focus on alterations in immune cell homing pathways in IBD. Unraveling the mechanisms underlying the immune post‐code system would assist in achieving the goal of tissue‐specific immunotherapy. (Inflamm Bowel Dis 2010)

Microbiota/Host Crosstalk Biomarkers: Regulatory Response of Human Intestinal Dendritic Cells Exposed to Lactobacillus Extracellular Encrypted Peptide

The human gastrointestinal tract is exposed to a huge variety of microorganisms, either commensal or pathogenic; at this site, a balance between immunity and immune tolerance is required. Intestinal dendritic cells (DCs) control the mechanisms of immune response/tolerance in the gut. In this paper we have identified a peptide (STp) secreted by Lactobacillus plantarum, characterized by the abundance of serine and threonine residues within its sequence. STp is encoded in one of the main extracellular proteins produced by such species, which includes some probiotic strains, and lacks cleavage sites for the major intestinal proteases. When studied in vitro, STp expanded the ongoing production of regulatory IL-10 in human intestinal DCs from healthy controls. STp-primed DC induced an immunoregulatory cytokine profile and skin-homing profile on stimulated T-cells. Our data suggest that some of the molecular dialogue between intestinal bacteria and DCs may be mediated by immunomodulatory peptides, encoded in larger extracellular proteins, secreted by commensal bacteria. These peptides may be used for the development of nutraceutical products for patients with IBD. In addition, this kind of peptides seem to be absent in the gut of inflammatory bowel disease patients, suggesting a potential role as biomarker of gut homeostasis.

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.

Low Muscularity and Myosteatosis Is Related to the Host Systemic Inflammatory Response in Patients Undergoing Surgery for Colorectal Cancer.

Objective:We examined the relationships between computed tomography (CT)–defined skeletal muscle parameters and the systemic inflammatory response (SIR) in patients with operable primary colorectal cancer (CRC). Background:Muscle depletion is characterized by a reduced muscle mass (myopenia) and increased infiltration by inter- and intramuscular fat (myosteatosis). It is recognized as a poor prognostic indicator in patients with cancer, but the underlying factors remain unclear. Methods:A total of 763 patients diagnosed with CRC undergoing elective surgical resection between 2006 and 2013 were included. Image analysis of CT scans was used to calculate Lumbar skeletal muscle index (LSMI), and mean muscle attenuation (MA). The SIR was quantified by the preoperative neutrophil to lymphocyte ratio (NLR) and albumin levels. Correlation and multivariate regression analysis was performed to identify independent relationships between patient SIR and muscle characteristics. Results:Patients with NLR > 3 had significantly lower LSMI and lower MA than those with NLR < 3 [LSMI = 42.07 cm2m−2 vs 44.27 cm2m−2 (P = 0.002) and MA = 30.04 Hounsfield unit (HU) vs 28.36 HU (P = 0.016)]. Multivariate logistic regression analysis showed that high NLR [odds ratio (OR) = 1.78 (95% confidence interval [CI]: 1.29–2.45), P < 0.001] and low albumin [OR = 1.80 (95% CI: 1.17–2.74), P = 0.007] were independent predictors of reduced muscle mass. High NLR was significantly related with a low mean MA and hence myosteatosis [OR = 1.60 (95% CI: 1.03–2.49), P = 0.038]. Conclusions:These results highlight a direct association between myopenia, myosteatosis, and the host SIR in patients with operable CRC. A better understanding of factors that regulate muscle changes such as myopenia and myosteatosis may lead to the development of novel therapies that influence a more metabolically “healthy” skeletal muscle and potentially alter cancer outcomes.

Adipose tissue of human omentum is a major source of dendritic cells, which lose MHC class II and stimulatory function in Crohn's disease

Adipose tissue is reported to contain monocyte‐like pre‐adipocytes, which may mature into macrophages, contributing to local inflammation. Dendritic cells (DC) can be derived from monocytes and initiate and regulate primary immune responses. We hypothesized, therefore, that adipose tissue may provide DC involved in local immune activity. To test this, we studied cells from human omental adipose tissue samples from 17 patients with benign gynecological disease. The hypothesis that adipose tissue DC are involved in inflammatory disease was tested by comparing these cells with those from 18 patients with Crohns disease, where hypertrophy of adipose tissue suggests involvement in disease. A high proportion of the 1.33 ± 0.12 × 105 CD45‐positive cells/mg, obtained from control omenta, expressed CD11c, CD1a, and CD83; costimulatory molecules CD40, CD80, and CD86; and major histocompatibility complex (MHC) Class II but little CD14, CD16, or CD33. Omental cells showing morphological characteristics of DC were also observed. Metrizamide gradient‐enriched DC from these populations were potent stimulators of primary proliferation of allogeneic T cells in mixed leukocyte reactions. Increased numbers of CD45+ cells from omentum of Crohns patients (4.50±1.08×105 CD45+ cells/mg) contained higher percentages of CD11c+ and CD40+ cells (80.8±3.8% vs. 63.4±6, P=0.032; 77.9±4% vs. 58.8±6.5, P=0.029, respectively), but MHC Class II and stimulatory capacity were almost completely lost (P=<0.001), suggesting innate activation but lost capacity to stimulate adaptive immune responses. Granulocytes were also present amongst the omental cells from Crohns patients. Results indicated that omentum may provide DC, which could “police” local infections and contribute to and/or reflect local inflammatory activity.