Effect of food additives on key bacterial taxa and the mucosa-associated microbiota in Crohn's disease. The ENIGMA study.

Food additives have been linked to the pro-inflammatory microbial dysbiosis associated with Crohn's disease (CD) but the underlying ecological dynamics are unknown. Here, we examine how selection of food additives affects the growth of multiple strains of a key beneficial bacterium (Faecalibacterium prausnitzii), axenic clinical isolates of proinflammatory bacteria from CD patients (Proteus, Morganella, and Klebsiella spp.), and the consortia of mucosa-associated microbiota recovered from multiple Crohn's disease patients. Bacterial growth of the axenic isolates was evaluated using a habitat-simulating medium supplemented with either sodium sulfite, aluminum silicate, carrageenan, carboxymethylcellulose, polysorbate 80, saccharin, sucralose, or aspartame, intended to approximate concentrations found in food. The microbial consortia recovered from post-operative CD patient mucosal biopsy samples were challenged with either carboxymethylcellulose and/or polysorbate 80, and the bacterial communities compared to unchallenged consortia by 16S rRNA gene amplicon profiling. Growth of all F. prausnitzii strains was arrested when either sodium sulfite or polysorbate 80 was added to cultures at baseline or mid-exponential phase of growth, and the inhibitory effects on the Gram-negative bacteria by sodium sulfite were conditional on oxygen availability. The effects from polysorbate 80, saccharin, carrageenan, and/or carboxymethylcellulose on these bacteria were strain-specific. In addition to their direct effects on bacterial growth, polysorbate 80 and/or carboxymethylcellulose can drive profound changes in the CD mucosa-associated microbiota via niche expansion of Proteus and/or Veillonellaceae - both implicated in early Crohn's disease recurrence. These studies on the interaction of food additives with the enteric microbiota provide a basis for dietary management in Crohn's disease.

Novel strain-level resolution of Crohn's disease mucosa-associated microbiota via an ex vivo combination of microbe culture and metagenomic sequencing.

The mucosa-associated microbiota is widely recognized as a potential trigger for Crohn's disease pathophysiology but remains largely uncharacterised beyond its taxonomic composition. Unlike stool microbiota, the functional characterisation of these communities using current DNA/RNA sequencing approaches remains constrained by the relatively small microbial density on tissue, and the overwhelming amount of human DNA recovered during sample preparation. Here, we have used a novel ex vivo approach that combines microbe culture from anaerobically preserved tissue with metagenome sequencing (MC-MGS) to reveal patient-specific and strain-level differences among these communities in post-operative Crohn's disease patients. The 16 S rRNA gene amplicon profiles showed these cultures provide a representative and holistic representation of the mucosa-associated microbiota, and MC-MGS produced both high quality metagenome-assembled genomes of recovered novel bacterial lineages. The MC-MGS approach also produced a strain-level resolution of key Enterobacteriacea and their associated virulence factors and revealed that urease activity underpins a key and diverse metabolic guild in these communities, which was confirmed by culture-based studies with axenic cultures. Collectively, these findings using MC-MGS show that the Crohn's disease mucosa-associated microbiota possesses taxonomic and functional attributes that are highly individualistic, borne at least in part by novel bacterial lineages not readily isolated or characterised from stool samples using current sequencing approaches.

Variants in ACTG2 underlie a substantial number of Australasian patients with primary chronic intestinal pseudo-obstruction.

BACKGROUND: Primary chronic intestinal pseudo-obstruction (CIPO) is a rare, potentially life-threatening disorder characterized by severely impaired gastrointestinal motility. The objective of this study was to examine the contribution of ACTG2, LMOD1, MYH11, and MYLK mutations in an Australasian cohort of patients with a diagnosis of primary CIPO associated with visceral myopathy. METHODS: Pediatric and adult patients with primary CIPO and suspected visceral myopathy were recruited from across Australia and New Zealand. Sanger sequencing of the genes encoding enteric gamma-actin (ACTG2) and smooth muscle leiomodin (LMOD1) was performed on DNA from patients, and their relatives, where available. MYH11 and MYLK were screened by next-generation sequencing. KEY RESULTS: We identified heterozygous missense variants in ACTG2 in 7 of 17 families (~41%) diagnosed with CIPO and its associated conditions. We also identified a previously unpublished missense mutation (c.443C>T, p.Arg148Leu) in one family. One case presented with megacystis-microcolon-intestinal hypoperistalsis syndrome in utero with subsequent termination of pregnancy at 28 weeks' gestation. All of the substitutions identified occurred at arginine residues. No likely pathogenic variants in LMOD1, MYH11, or MYLK were identified within our cohort. CONCLUSIONS AND INFERENCES: ACTG2 mutations represent a significant underlying cause of primary CIPO with visceral myopathy and associated phenotypes in Australasian patients. Thus, ACTG2 sequencing should be considered in cases presenting with hypoperistalsis phenotypes with suspected visceral myopathy. It is likely that variants in other genes encoding enteric smooth muscle contractile proteins will contribute further to the genetic heterogeneity of hypoperistalsis phenotypes.

Visceral adiposity predicts post-operative Crohn's disease recurrence.

BACKGROUND: Excessive visceral adipose tissue has been associated with poorer outcomes in patients with inflammatory bowel disease. AIM: To determine whether body composition is associated with outcome in a prospective study of post-operative Crohn's disease patients. METHODS: The POCER study evaluated management strategies for prevention of post-operative Crohn's disease recurrence; subjects were enrolled after resection of all macroscopic Crohn's disease and were randomised to early endoscopy and possible treatment escalation, or standard care. The primary endpoint was endoscopic recurrence at 18 months. 44 subjects with cross-sectional abdominal imaging were studied, and body composition analysis performed using established techniques to measure visceral adipose tissue area, subcutaneous adipose tissue area, and skeletal muscle area. RESULTS: The body composition parameter with the greatest variance was visceral adipose tissue. Regardless of treatment, all subjects with visceral adipose tissue/height2 >1.5 times the gender-specific mean experienced endoscopic recurrence at 18 months (compared to 47%) [relative risk 2.1, 95% CI 1.5-3.0, P = 0.012]. Waist circumference correlated strongly with visceral adipose tissue area (ρ = 0.840, P < 0.001). Low skeletal muscle was prevalent (41% of patients), but did not predict endoscopic recurrence; however, appendicular skeletal muscle indices correlated inversely with faecal calprotectin (ρ = 0.560, P = 0.046). CONCLUSIONS: Visceral adiposity is an independent risk factor for endoscopic recurrence of Crohn's disease after surgery. Sarcopenia correlates with inflammatory biomarkers. Measures of visceral adipose tissue may help to stratify risk in post-operative management strategies.

Efficacy of thiopurines and adalimumab in preventing Crohn's disease recurrence in high-risk patients - a POCER study analysis.

BACKGROUND: Crohn's disease recurs in the majority of patients after intestinal resection. AIM: To compare the relative efficacy of thiopurines and anti-TNF therapy in patients at high risk of disease recurrence. METHODS: As part of a larger study comparing post-operative management strategies, patients at high risk of recurrence (smoker, perforating disease, ≥2nd operation) were treated after resection of all macroscopic disease with 3 months metronidazole together with either azathioprine 2 mg/kg/day or mercaptopurine 1.5 mg/kg/day. Thiopurine-intolerant patients received adalimumab induction then 40 mg fortnightly. Patients underwent colonoscopy at 6 months with endoscopic recurrence assessed blind to treatment. RESULTS: A total of 101 patients [50% male; median (IQR) age 36 (25-46) years] were included. There were no differences in disease history between thiopurine- and adalimumab-treated patients. Fifteen patients withdrew prior to 6 months, five due to symptom recurrence (of whom four were colonoscoped). Endoscopic recurrence (Rutgeerts score i2-i4) occurred in 33 of 73 (45%) thiopurine vs. 6 of 28 (21%) adalimumab-treated patients [intention-to-treat (ITT); P = 0.028] or 24 of 62 (39%) vs. 3 of 24 (13%) respectively [per-protocol analysis (PPA); P = 0.020]. Complete mucosal endoscopic normality (Rutgeerts i0) occurred in 17/73 (23%) vs. 15/28 (54%) (ITT; P = 0.003) and in 27% vs. 63% (PPA; P = 0.002). The most advanced disease (Rutgeerts i3 and i4) occurred in 8% vs. 4% (thiopurine vs. adalimumab). CONCLUSIONS: In Crohn's disease patients at high risk of post-operative recurrence adalimumab is superior to thiopurines in preventing early disease recurrence.

Outcome of behavioural treatment for idiopathic chronic constipation.

BACKGROUND/AIM: Behavioural therapy is effective in patients with chronic intractable constipation despite standard treatment, but long-term results in unselected patients are unclear. This study investigates the effects of behavioural therapy on symptoms, subjective well-being, and the physical and mental quality of life. METHODS: Patients who had failed standard care for idiopathic chronic constipation underwent behavioural therapy in a specialist clinic. Symptom severity and quality of life were assessed before and after therapy using the 'Constipation Scoring System' and the Short-Form 36 questionnaire. The primary outcome was subjective perception of improvement. Secondary outcomes were symptoms of constipation and quality of life scores. RESULTS: Of 233 consecutive patients with self-reported constipation (median symptom duration 5-10 years, median age 44 years, females 86%), 180 (77%) completed treatment in a median of three (range 1-7) sessions. One hundred and sixty-five patients (71% of all referrals or 92% of those completing treatment) reported subjective improvement. Median bowel frequency improved from once every 2-7 days to 1-3 per day (P = 0.05). Pain and bloating improved in more than 80% of patients. The Short-Form 36 physical (P < 0.05) and mental (P < 0.05) composite scores improved significantly. Patients with a longer duration of symptoms were less likely to complete treatment. Digital evacuation prior to treatment was a predictor of poor outcome. CONCLUSION: Behavioural therapy is associated with significant improvement in symptoms of chronic constipation and quality of life. Non-drug therapies that successfully treat patients with functional gut disorders resistant to standard treatment are needed in the mainstream provision of care.

Inflammatory bowel disease cancer surveillance in a tertiary referral hospital: attitudes and practice.

BACKGROUND: Physician adherence to guidelines for colorectal cancer (CRC) surveillance in inflammatory bowel disease (IBD) is often poor. This may lead to adverse patient outcomes and excess endoscopic workload. AIMS: To assess the attitudes and practice of IBD specialists in a tertiary centre towards colonoscopic surveillance. METHODS: First, a questionnaire evaluating attitudes and approach to CRC surveillance was issued to 36 clinicians at one tertiary referral hospital. Second, a retrospective audit of IBD surveillance colonoscopy practice over a 2-year period was performed. RESULTS: Questionnaire response rate was 97%. Sixty-nine per cent of respondents were aware of, and used, Australian guidelines. Surveillance was undertaken by all clinicians in patients with extensive colitis, 83% in patients with left-sided colitis and 51% in patients with proctitis. Seventy-six per cent used chromoendoscopy, and 47% took 10 to 20 random biopsies. Colectomy was considered appropriate in 0% for unifocal low-grade dysplasia, 35% for multifocal low-grade dysplasia and 83% for high-grade dysplasia. Sixty-six per cent would remove elevated dysplastic lesions endoscopically. The audit identified 103 surveillance colonoscopies in 81 patients. Chromoendoscopy was used in 21% of cases, and the median number of random biopsies was 13. Sixty-two per cent of colonoscopies were performed outside the guidelines in relation to colonoscopic frequency. Following colonoscopy, an appropriate recommendation for subsequent surveillance was documented in 40% of cases. CONCLUSIONS: Knowledge and practice of CRC surveillance in IBD vary among specialist clinicians and often deviate from guidelines. Many clinicians perform surveillance earlier and more frequently than recommended. These findings have implications for patient outcomes and workload.

Development and validation of a patient-reported disability measurement tool for patients with inflammatory bowel disease.

BACKGROUND: Inflammatory bowel disease can impact on a patient's ability to maintain normal physical and mental function, and fulfil their social, family and work roles. Aspects of disability in IBD have received little attention. AIM: To develop, validate and apply a questionnaire directed towards evaluating these disease aspects. METHODS: A literature review on disability in IBD was undertaken, and opinion about aspects of disability to measure was sought from six IBD-specialised gastroenterologists. A questionnaire was developed, and IBD patients completed the new disability questionnaire, the SF-36 and the short-IBD (SIBDQ - 10 point). A subgroup of patients completed the questionnaire again 4 weeks later. Healthy volunteers were studied as a control group. RESULTS: A total of 116 IBD out-patients were approached, of whom 81 (52 Crohn's disease and 28 ulcerative colitis) participated. Nineteen patients were re-evaluated at 4 weeks. Twenty-five controls were studied. All subscales demonstrated good Cronbach's alpha reliability and reproducibility. There was a significant inverse correlation between the disability score and the SIBDQ and between the disability score and the SF36 and a positive correlation with the Crohn's Disease Activity Index (CDAI) (all P < 0.001). Disability differed between ulcerative colitis and controls, but not between active and inactive disease. CONCLUSIONS: The new disability questionnaire is sensitive for detecting disability, is reliable and reproducible, and correlates with disease activity in Crohn's disease, but not ulcerative colitis. Further prospective testing is now needed in the longer term, larger patient populations and in different countries and ethnicities.

Postoperative recurrence of Crohn's disease: impact of endoscopic monitoring and treatment step-up.

AIM: Eighty per cent of patients with Crohn's disease require surgery, of whom 70% will require a further operation. Recurrence occurs at the anastomosis. Although often recommended, the impact of postoperative colonoscopy and treatment adjustment is unknown. METHOD: Patients with a bowel resection over a 10-year period were reviewed and comparison made between those who did and did not have a postoperative colonoscopy within 1 year of surgery, and those who did or did not have a step-up in drug therapy. RESULTS: Of 222 patients operated on, 136 (65 men, mean age 33 years, mean disease duration 8 years, median follow-up 4 years) were studied. Of 70 patients with and 66 without postoperative colonoscopy, clinical recurrence occurred in 49% and 48% (NS) and further surgery in 9% and 5% (NS). Eighty-nine per cent of colonoscoped patients had a decision based on the colonoscopic findings: of these, 24% had a step-up of drug therapy [antibiotics (n =10), aminosalicylates (n=2), thiopurine (n=5), methotrexate (n=1)] and 76% had no step-up in drug therapy. In colonoscoped patients clinical recurrence occurred in 9 (60%) of 15 patients with, and 23 (49%) of 47 without step-up and surgical recurrence in 2 (13%) of 15 and 4 (9%) of 47 (NS). CONCLUSION: Clinical recurrence occurs in a majority of patients soon after surgery. In this cohort, there was no clinical benefit from colonoscopy or increased drug therapy within 1 year after operation. However, the response to the endoscopic findings was not standardized and immunosuppressive therapy was uncommon. Standardizing timing of colonoscopy and drug therapy, including more intense therapy, may improve outcome, although this remains to be proven.

A mechanistic role for leptin in human dendritic cell migration: differences between ileum and colon in health and Crohn's disease.

Dendritic cells (DC) migrate to lymph nodes on expression of C-C motif chemokine receptor 7 (CCR7) and control immune activity. Leptin, an immunomodulatory adipokine, functions via leptin receptors, signaling via the long isoform of receptor, LepRb. Leptin promotes DC maturation and increases CCR7 expression on blood DC. Increased mesenteric fat and leptin occur early in Crohn's disease (CD), suggesting leptin-mediated change in intestinal CCR7 expression on DC as a pro-inflammatory mechanism. We have demonstrated CCR7 expression and capacity to migrate to its ligand macrophage inflammatory protein 3ß in normal human ileal DC but not colonic or blood DC. In CD, functional CCR7 was expressed on DC from all sites. Only DC populations containing CCR7-expressing cells produced LepRb; in vitro exposure to leptin also increased expression of functional CCR7 in intestinal DC in a dose-dependent manner. In conclusion, leptin may regulate DC migration from gut, in homeostatic and inflammatory conditions, providing a link between mesenteric obesity and inflammation.

Randomised clinical trial: the efficacy of prucalopride in patients with chronic intestinal pseudo-obstruction--a double-blind, placebo-controlled, cross-over, multiple n = 1 study.

BACKGROUND: Chronic intestinal pseudo-obstruction is a disabling condition for which there are no established drug therapies. The condition is caused by a diverse range of intestinal myopathies and neuropathies. AIM: To assess the therapeutic efficacy of prucalopride, a selective high-affinity 5-HT(4) receptor agonist, we employed a multiple n = 1 study design. Each patient acted as his/her own control, each day counting as one treatment episode, allowing comparison of 168 days on each of active drug and placebo. METHODS: Double-blind, randomised, placebo-controlled, cross-over trial of four 12-week treatment periods, with 2-4 mg prucalopride or placebo daily. In each of the first and second 6 months there was a prucalopride and a placebo treatment. Patients with proven chronic intestinal pseudo-obstruction, including dilated gut, were included. Evaluation was by patient diary and global evaluation. RESULTS: Seven patients participated (mean 42 years, five female, median symptom duration 11 years). Three discontinued, two due to study length, and one on prucalopride due to unrelated malnutrition and bronchopneumonia. Four patients (three visceral myopathy and one visceral neuropathy) completed the study; prucalopride significantly improved pain in three of four patients, nausea in two, vomiting in one, bloating in four and analgesic intake. Bowel function was not changed substantially. CONCLUSIONS: n = 1 studies in rare conditions allow drug efficacy assessment. Prucalopride relieves symptoms in selected patients with chronic pseudo-obstruction.

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 Crohn's 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.

Adalimumab sustains steroid-free remission after 3 years of therapy for Crohn's disease.

BACKGROUND: Treatments that achieve sustainable steroid-free clinical remission in Crohn's disease are needed; however, long-term steroid-sparing efficacy data are limited. AIM: To evaluate steroid-sparing efficacy and the impact of steroid discontinuation on adverse events during treatment of Crohn's disease with adalimumab in the phase III randomised, double-blind 1-year CHARM trial and for an additional 2 years in its open-label extension ADHERE. METHODS: Steroid-free remission and response and steroid-sparing (≥50% steroid dose reduction) remission rates were evaluated over 3 years in patients who were taking corticosteroids at CHARM baseline. RESULTS: Of 778 patients randomised in CHARM (including those who did not achieve clinical response to open-label induction therapy), 313 patients (40%) were on corticosteroids at baseline. In the 206 patients randomised to adalimumab, rates of steroid-free remission at 1 year and 3 years were 26% and 23% respectively; corresponding rates were 29% and 25% for steroid-sparing remission and 32% and 28% for steroid-free response. Although the incidence of serious infections with adalimumab treatment during CHARM was higher in patients taking steroids at baseline than those who were not, the rates of overall adverse events, serious infections and opportunistic infections were lower in patients who were able to discontinue corticosteroids than those who remained on steroids. CONCLUSION: Adalimumab therapy resulted in modest but clinically meaningful rates of steroid-free remission, sustained over 3 years of treatment, in a heavily pretreated population of patients with Crohn's disease receiving steroids at the start of therapy (http://www.clinicaltrials.gov number: NCT00077779).

Review article: defining remission in ulcerative colitis.

BACKGROUND: There is no international agreement on scoring systems used to measure disease activity in ulcerative colitis, nor is there a validated definition for disease remission. AIM: To review the principles and components for defining remission in ulcerative colitis and propose a definition that will help improve patient outcomes. METHODS: A review of current standards of remission from the perspective of clinical trials, guidelines, clinical practice and patients was conducted by the authors. Selected literature focused on the components of a definition of remission, the utility of a definition and treatment strategies, based on current definitions. RESULTS: Different definitions of remission affect the assessment of outcome and make it difficult to compare trials. In the clinic, endoscopy is rarely used to confirm remission, because mucosal healing has only recently begun to be related to the duration of subsequent remission in a way that will affect clinical practice. Histopathology may be the ultimate arbiter of mucosal healing. There is no agreement on the definition of remission in current guidelines. Patient-defined remission may predict endoscopic remission, but has yet to be shown to predict duration of remission. CONCLUSIONS: A standard based on clinical symptoms and endoscopy is proposed. Histopathology is a third dimension of remission that may have prognostic value. The definition of remission should help predict long-term outcome. The expectations of patients and their physicians need to be raised, as the goal of treatment of active ulcerative colitis should be to induce remission.

Diagnosis and treatment of chronic constipation--a European perspective.

BACKGROUND: Although constipation can be a chronic and severe problem, it is largely treated empirically. Evidence for the efficacy of some of the older laxatives from well-designed trials is limited. Patients often report high levels of dissatisfaction with their treatment, which is attributed to a lack of efficacy or unpleasant side-effects. Management guidelines and recommendations are limited and are not sufficiently current to include treatments that became available more recently, such as prokinetic agents in Europe. PURPOSE: We present an overview of the pathophysiology, diagnosis, current management and available guidelines for the treatment of chronic constipation, and include recent data on the efficacy and potential clinical use of the more newly available therapeutic agents. Based on published algorithms and guidelines on the management of chronic constipation, secondary pathologies and causes are first excluded and then diet, lifestyle, and, if available, behavioral measures adopted. If these fail, bulk-forming, osmotic, and stimulant laxatives can be used. If symptoms are not satisfactorily resolved, a prokinetic agent such as prucalopride can be prescribed. Biofeedback is recommended as a treatment for chronic constipation in patients with disordered defecation. Surgery should only be considered once all other treatment options have been exhausted.

Preliminary examination of the relations between disease activity, illness perceptions, coping strategies, and psychological morbidity in Crohn's disease guided by the common sense model of illness.

BACKGROUND: An individual's psychological adjustment to illness is influenced by disease severity, illness perceptions, and coping strategies. A more precise understanding of the contribution of each of these factors to a patient's well-being may influence the kind of psychological support required by patients. This study therefore aimed to characterize the contributors to psychological well-being in patients with Crohn's disease (CD). The design was a cross-sectional questionnaire-based study. METHODS: Ninety-six CD patients (34 males, 62 females, mean age 38 years) attending a tertiary hospital inflammatory bowel disease outpatient clinic were studied. Disease severity was evaluated according to the Crohn's Disease Activity Index (CDAI), coping styles assessed with the Carver Brief COPE scale, illness perceptions explored with the Brief Illness Perceptions Questionnaire (BIPQ), and anxiety and depression measured using the Hospital Anxiety and Depression Scale (HADS). RESULTS: Combining the questionnaire data using structural equation modeling resulted in a final model with an excellent fit (χ(2) (7) = 10.42, P = 0.17, χ(2) /N = 1.49, root mean square error of approximation (RMSEA) < 0.07, comparative fit index (CFI) > 0.97, Goodness-of-fit index (GFI) > 0.97). Disease activity had a significant direct influence on illness perceptions (ß = 51, P < 0.001). In turn, illness perceptions had a significant direct influence on depression and anxiety (ß = 41, P < 0.001, ß = 0.40, P < 0.001, respectively). Use of emotional coping strategies was associated significantly (P < 0.001) with the presence of anxiety and depression. CONCLUSIONS: There is an interrelationship between disease activity, illness perceptions, coping strategies, and depression and anxiety. These aspects of psychological processing provide a framework and direction for the psychological support that patients with CD require.

Intestinal dendritic cells: their role in bacterial recognition, lymphocyte homing, and intestinal inflammation.

Dendritic cells (DCs) play a key role in discriminating between commensal microorganisms and potentially harmful pathogens and in maintaining the balance between tolerance and active immunity. The regulatory role of DC is of particular importance in the gut where the immune system lies in intimate contact with the highly antigenic external environment. Intestinal DC constantly survey the luminal microenvironment. They act as sentinels, acquiring antigens in peripheral tissues before migrating to secondary lymphoid organs to activate naive T cells. They are also sensors, responding to a spectrum of environmental cues by extensive differentiation or maturation. Recent studies have begun to elucidate mechanisms for functional specializations of DC in the intestine that may include the involvement of retinoic acid and transforming growth factor-ß. Specialized CD103(+) intestinal DC can promote the differentiation of Foxp3(+) regulatory T cells via a retinoic acid-dependent process. Different DC outcomes are, in part, influenced by their exposure to microbial stimuli. Evidence is also emerging of the close interaction between bacteria, epithelial cells, and DC in the maintenance of intestinal immune homeostasis. Here we review recent advances of functionally specialized intestinal DC and their mechanisms of antigen uptake and recognition. We also discuss the interaction of DC with intestinal microbiota and their ability to orchestrate protective immunity and immune tolerance in the host. Lastly, we describe how DC functions are altered in intestinal inflammation and their emerging potential as a therapeutic target in inflammatory bowel disease.