The evolving epidemiology of inflammatory bowel disease

Systematic review: the role of tacrolimus in the management of Crohn's disease

BACKGROUND  Several published studies have evaluated the efficacy of tacrolimus in the management of Crohn's disease with variable conclusions. AIM  To review systematically the evidence examining the efficacy and safety of tacrolimus in treating Crohn's disease. METHODS  The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (PUBMED) and EMBASE (1984 to January 2011) were searched. Also, references from selected articles were examined. Case series (five or more patients), cohort and randomised controlled trials were eligible for inclusion, incorporating oral, intravenous or topical tacrolimus therapy. The primary outcome was induction of remission of active Crohn's disease. RESULTS  Eleven studies met the inclusion criteria which included 163 patients, of which 127 received tacrolimus therapy. In patients with luminal Crohn's disease, the crude pooled remission rate for tacrolimus was 44.3% (range, 7-69%) and the crude pooled response rate was 37.1% (range, 14-57%). For patients with perianal disease using systemic tacrolimus, crude pooled remission rate was 28.6% (range, 0-64%) and crude pooled response rate was 38.8% (range, 0-57%). Combining data from two studies using topical tacrolimus, 35.7% of patients achieved remission and 28.6% partial response. Nonserious adverse effects are common, particularly tremor, paraesthesia and headache. Reversible nephrotoxity occurred in 16% of patients. CONCLUSIONS  The current evidence; although of a poor quality, appears to support the use of tacrolimus in Crohn's disease. High quality randomised controlled trials are needed.

Characteristics and incidences of pediatric Crohn's disease in the decades before and after 2000

OBJECTIVE

The increasing incidence of pediatric Crohn's disease (CD) is well known in Western countries in the last two decades. This study was conducted to delineate the trends of incidence during this period and clinical patterns of pediatric CD in Taiwan.

METHODS

All children admitted to National Taiwan University Hospital between 1990 and 2009 who met the Porto Criteria for CD were included. Annual enrollment and clinical characteristics were retrospectively reviewed. The incidence was calculated by dividing the number of index cases by total hospitalized pediatric cases to minimize the bias caused by the growing number of hospitalized patients there. We quoted data and statistics from the Department of Health, Executive Yuan, Taiwan, and Accounting and Statistics, Executive Yuan, Taiwan, to present the social-economic changes in Taiwan in the recent decades.

RESULTS

The cumulative hospital-based incidence of CD rose from 13.2 per 100,000 to 25.4 per 100,000 children admitted to this hospital in the past two decades. The median age of diagnosis in the first decade of this study was less than that of the second decade. The other study parameters, including gender, disease activity at diagnosis, duration from disease onset to diagnosis, anatomic location and disease behavior, and symptoms at diagnosis, were not different.

CONCLUSIONS

This study showed that the hospital-based incidence of pediatric CD has been increasing in Taiwan in recent decades. Factors contributing to such an increase could be physicians' awareness of the disease, easier access to health care, and environmental factors.

Iridoid glycosides fraction of Folium syringae leaves modulates NF-κB signal pathway and intestinal epithelial cells apoptosis in experimental colitis

BACKGROUND AND AIMS

Iridoid glycosides (IG), the major active fraction of F. syringae leaves has been demonstrated to have strong anti-inflammatory properties to ulcerative colitis (UC) in our previous study. The aim of this study was to investigate whether IG modulates the inflammatory response in experimental colitis at the level of NF-κB signal pathway and epithelial cell apoptosis.

METHODS

UC in rats was induced by administration with dextran sulfate sodium (DSS) in drinking water. The inflammatory damage was assessed by disease activity index (DAI), macroscopic findings, histology and myeloperoxidase (MPO) activity. The effect of IG on pro-inflammatory cytokines TNF-α, IL-8, COX-2 and regulatory peptide TGF-β1 was measured. Epithelial cell apoptosis and the protein and mRNA expressions of Fas/FasL, Bcl-2/Bax, caspase-3, NF-κB p65, IκBα, p-IκBα and IKKβ were detected by TUNEL method, immunohistochemistry, Western blotting and real-time quantitative PCR, respectively.

RESULTS

IG significantly ameliorated macroscopic damage and histological changes, reduced the activity of MPO, and strongly inhibited epithelial cell apoptosis. Moreover, IG markedly depressed TNF-α, IL-8, COX-2 and TGF-β1 levels in the colon tissues in a dose-dependent manner. Furthermore, IG significantly blocked of NF-κB signaling by inhibiting IκBα phosphorylation/degradation and IKKβ activity, down-regulated the protein and mRNA expressions of Fas/FasL, Bax and caspase-3, and activated Bcl-2 in intestinal epithelial cells.

CONCLUSIONS

These results demonstrated for the first time that IG possessed marked protective effects on experimental colitis through inhibition of epithelial cell apoptosis and blockade of NF-κB signal pathway.

Antimicrobial peptide response to blood translocation of bacterial DNA in Crohn's disease is affected by NOD2/CARD15 genotype

BACKGROUND

Blood translocation of bacterial-DNA has been described in patients with Crohn's disease (CD). The host's immune cell types cooperate to respond against bacterial insults. Some antimicrobial peptides are inducible after culture with bacterial products and a linkage has been established between them and NOD2/CARD15. The aim was to test whether defensins and cathelicidin (LL-37) expression and NOD2/CARD15 mutations in blood neutrophils are related to molecular bacterial translocation events in CD patients.

METHODS

Fifty consecutively admitted CD patients and 15 healthy controls were included. Clinical and analytical characteristics of patients were considered. NOD2/CARD15 genotyping, presence of bacterial-DNA, defensin and cathelicidin gene, and protein levels in neutrophils and serum cytokine levels were studied.

RESULTS

Twenty patients (40%) presented bacterial-DNA in blood. Eleven were active and 9 were in remission. Bacterial-DNA was not present in controls. NOD2/CARD15 mutations were identified in 25 patients (50%), 15 of which were in remission. Sixty percent of bacterial-DNA(+) and 43% of bacterial-DNA(-) patients showed a NOD2/CARD15 mutation. β-Defensin 2 and LL-37 mRNA and protein levels were upregulated in bacterial-DNA(+) patients. β-Defensin 2 and LL-37 expression correlated with bacterial-DNA concentration only in patients with a wildtype NOD2/CARD15 genotype. Cultured neutrophils of bacterial-DNA(-) patients confirmed the muramyl dipeptide-independent association between DEFB2 and LL-37 with bacterial-DNA concentration in wildtype NOD2/CARD15 patients. Cytokine levels were increased in bacterial-DNA(+) patients and correlated with bacterial-DNA concentration. NOD2/CARD15 genotype did not influence this correlation.

CONCLUSIONS

β-Defensin 2, LL-37, and proinflammatory cytokines are increased in CD patients with bacterial-DNA in a concentration-dependent manner. NOD2/CARD15 plays a key role in the regulation of this response.

Anti-inflammatory effects of methanol extract of Patrinia scabiosaefolia in mice with ulcerative colitis

ETHNOPHARMACOLOGICAL RELEVANCE

Patrinia scabiosaefolia Fisch is used in folk medicines to treat intestinal abscesses, acute appendicitis, and dysentery in Asia. Although recent reports indicate that Patrinia scabiosaefolia has sedative and anti-tumor effects, its effects on ulcerative colitis have not been previously explored.

AIM OF THE STUDY

To determine the effects and the mode of action of the methanol extract of the roots of Patrinia scabiosaefolia (PME) on a model of colitis in mice induced by dextran sulfate sodium (DSS).

MATERIALS AND METHODS

We induced colitis using DSS in 5-week-ICR mice over 7 days and estimated disease activity index (DAI), which took into account body weight, stool consistency, gross bleeding, and tissue myeloperoxidase (MPO) accumulation. Colon lengths and spleen weights were measured. Histological changes were observed by H&E staining. Pro-inflammatory mediators, namely, nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), were determined using Griess assays, immunoassays, and by quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR), respectively.

RESULTS

PME significantly attenuated DSS-induced DAI scores and tissue MPO accumulation, which implied that it suppressed weight loss, diarrhea, gross bleeding, and the infiltrations of immune cells. PME administration also effectively and dose-dependently prevented shortening of colon length and enlargement of spleen size. Histological examinations indicated that PME suppressed edema, mucosal damage, and the loss of crypts induced by DSS. Furthermore, PME inhibited the abnormal secretions and mRNA expressions of pro-inflammatory cytokines, such as, TNF-α, IL-1β, and IL-6.

CONCLUSION

These results suggest that PME has an anti-inflammatory effect at colorectal sites that is due to the down-regulations of the productions and expressions of inflammatory mediators, and that it may have therapeutic value in the setting of inflammatory bowel disease (IBD).

Relapse rate following azathioprine withdrawal in maintaining remission for Crohn's disease: a meta-analysis

BACKGROUND

The duration of use of azathioprine (Aza) and 6-mercaptopurine (6-MP) for maintaining remission for Crohn's disease is debatable.

AIM

To examine whether Aza/6-MP can be safely withdrawn in patients with Crohn's disease who have been in remission.

METHODS

The following databases were searched: MEDLINE (1950-September 2010), EMBASE (1980-September 2010), CINHAL (1981-September 2010), PubMed (1950-September 2010), and the Cochrane Central Register of Controlled Trials (CENTRAL). Randomised controlled and cohort studies comparing azathioprine continuation versus placebo or no treatment were eligible for inclusion. Primary outcomes were relapse rate after discontinuation of Aza/6-MP at 6, 12, and 18 months, and 5 and 10 years.

RESULTS

Five studies, with 256 patients and 168 controls, met the inclusion criteria. Stopping azathioprine/6-MP was found to significantly increase the risk of relapse at 6, 12, and 18 months with pooled odds ratios of 0.22 (95% CI 0.09-0.53), 0.25 (95% CI 0.11-0.56), and 0.35 (95% CI 0.21-0.6), respectively. Two trials examined relapse rate at 5 years with pooled OR 0.53 (95% CI 0.13-2.21). No trials looking at relapse rates beyond 5 years were identified.

CONCLUSIONS

There is a clear benefit of continuing Aza/6-MP for at least 18 months to maintain remission for Crohn's disease patients who established remission. There is not enough evidence to provide clear guidance on whether or not to continue Aza/6-MP treatment beyond 18 months. Well-designed randomised controlled trials addressing this issue are needed.

IRF4 regulates IL-17A promoter activity and controls RORγt-dependent Th17 colitis in vivo

BACKGROUND

The transcription factor IRF4 is involved in several T-cell-dependent chronic inflammatory diseases. To elucidate the mechanisms for pathological cytokine production in colitis, we addressed the role of the IRF transcription factors in human inflammatory bowel disease (IBD) and experimental colitis.

METHODS

IRF levels and cytokine production in IBD patients were studied as well as the effects of IRF4 deficiency in experimental colitis.

RESULTS

In contrast to IRF1, IRF5, and IRF8, IRF4 expression in IBD was augmented in the presence of active inflammation. Furthermore, IRF4 levels significantly correlated with IL-6 and IL-17 mRNA expression and to a lesser extent with IL-22 mRNA expression in IBD. To further explore the role of IRF4 under in vivo conditions, we studied IRF4-deficient and wildtype mice in experimental colitis. In contrast to DSS colitis, IRF4 deficiency was protective in T-cell-dependent transfer colitis associated with reduced RORα/γt levels and impaired IL-6, IL-17a, and IL-22 production, suggesting that IRF4 acts as a master regulator of mucosal Th17 cell differentiation. Subsequent mechanistic studies using database analysis, chromatin immunoprecipitation, and electrophoretic mobility shift assays identified a novel IRF4 binding site in the IL-17 gene promoter. Overexpression of IRF4 using retroviral infection induced IL-17 production and IL-17 together with IL-6 induced RORγt expression.

CONCLUSIONS

IRF4 can directly bind to the IL-17 promotor and induces mucosal RORγt levels and IL-17 gene expression thereby controlling Th17-dependent colitis. Targeting of this molecular mechanism may lead to novel therapeutic approaches in human IBD.

Role of TIM-4 in innate or adaptive immune response

Human being living in constant contact with microbes and pathogen and in the process has developed a recognition pattern of pathogenic structure in the immune cells. The gut lumen has high density of microbes thus the immune response is slightly tolerable to certain microbes, known as commensal flora. These microbes along with other innocuous agents do not cause any inflammation response normally, and are considered as harmless by the immune cells. In immune hypersensitivity condition, such as colitis or food allergy, this mechanism is disturbed. T cell immunoglobulin and mucin domain (TIM)-4 is a phosphatidylserine receptor expressed in mature antigen presenting cells. It is shown that TIM-4 and its ligand TIM-1 are associated in intestinal immune response. However the characteristic of TIM-4 sometimes seems to be two-faced and there is a possibility that TIM-4 also bind to other ligands.

Experimental inflammatory bowel disease: insights into the host-microbiota dialog

Inflammatory bowel disease appears to result from an abnormal host immune response to the intestinal microbiota. Experimental models have allowed the dissection of the complex dialog between the host and its microbiota. Through genetic manipulation of the host genome the immune compartments, cells, molecules, and genes that are critical for maintenance of intestinal homeostasis are being identified. Genetic association studies in humans have identified over 100 susceptibility loci. Although there is remarkable coherence between the experimental model and the human genetic data, a full understanding of the mechanisms involved in genetic susceptibility to IBD and of gene-gene and gene-environmental interactions will require a "next generation" of experimental models.

Behavioral interventions may prolong remission in patients with inflammatory bowel disease

Inflammatory Bowel Diseases (IBDs) are chronic, relapsing and remitting gastrointestinal conditions with no known cure. Previous studies have linked behavioral factors, including stress and medication adherence, to relapse.

PURPOSE

We sought to determine the effect of participation in a behavioral self-management program on incidence of flare within 12 months following behavioral intervention when compared to the natural history of flare incidence prior to program participation.

RESULTS

Results from a 2-level regression model indicated that those participants in the treatment group were 57% less likely to flare in the following 12 months (compared to 18% in the control group). The decline in "flare odds" was about 2 times greater in treatment versus controls (OR=0.52, t(34)=2.07, p<0.05). Office visits, ER visits, and disease severity (all p<0.05) were identified as moderators of flare risk.

CONCLUSIONS

We have demonstrated 1) a statistical model estimating the likelihood of flare rates in the 12 months following a behavioral intervention for IBD (compared to a control condition), and 2) that the introduction of a behavioral intervention can alter the natural course of a chronic, relapsing and remitting gastrointestinal condition such as IBD.

The potential role of a self-management intervention for ulcerative colitis: a brief report from the ulcerative colitis hypnotherapy trial

Inflammatory bowel diseases (IBD) are chronic inflammatory illnesses marked by unpredictable disease flares, which occur spontaneously and/or in response to external triggers, especially personal health behaviors. Behavioral triggers of flare may be responsive to disease self-management programs. We report on interim findings of a randomized controlled trial of gut-directed hypnotherapy (HYP, n = 19) versus active attention control (CON, n = 17) for quiescent ulcerative colitis (UC). To date, 43 participants have enrolled; after 5 discontinuations (1 in HYP) and 2 exclusions due to excessive missing data, 36 were included in this preliminary analysis. Aim 1 was to determine the feasibility and acceptability of HYP in UC. This was achieved, demonstrated by a reasonable recruitment rate at our outpatient tertiary care clinic (20%), high retention rate (88% total), and our representative IBD sample, which is reflected by an equal distribution of gender, an age range between 21 and 69, recruitment of ethnic minorities (∽20%), and disease duration ranging from 1.5 to 35 years. Aim 2 was to estimate effect sizes on key clinical outcomes for use in future trials. Effect sizes (group × time at 20 weeks) were small to medium for IBD self-efficacy (.34), Inflammatory Bowel Disease Questionnaire (IBDQ) total score (.41), IBDQ bowel (.50), and systemic health (.48). Between-group effects were observed for the IBDQ bowel health subscale (HYP > CON; p = .05) at 20 weeks and the Short Form 12 Health Survey Version 2 (SF-12v2) physical component (HYP > CON; p < .05) at posttreatment and 20 weeks. This study supports future clinical trials testing gut-directed HYP as a relapse prevention tool for IBD.

Inflammatory manifestations at colonoscopy in patients with colonic diverticular disease

BACKGROUND

Ulcerative colitis with diverticulosis (UCD), segmental colitis associated with diverticulosis (SCAD) and acute uncomplicated diverticulitis (AUD) may affect the same colonic regions, but the real incidence of these entities in clinical practice is unknown.

AIM

To assess the incidence and the endoscopic findings of UCD, SCAD and AUD.

METHODS

From January 2004 to June 2009, 8525 consecutive colonoscopies were performed. Diagnosis of the diseases was based on specific endoscopic and histological (UCD and SCAD), and on endoscopic and radiological (AUD) patterns.

RESULTS

Ulcerative colitis with diverticulosis was diagnosed in 25 patients (0.3%), SCAD was diagnosed in 129 patients (2%) and AUD was diagnosed in 130 patients (2%). In UCD, the inflammation in colonic area harbouring diverticula always affects the overall colonic mucosa in all cases, involving also diverticular orifices. The endoscopic characteristic of SCAD is that inflammation is mainly detected within the inter-diverticular mucosa without involvement of the diverticular orifices. In AUD, the inflammation affects primarily diverticular orifice and peri-diverticular mucosa.

CONCLUSIONS

In clinical practice, the incidence of mucosal inflammation in the presence of colonic diverticular disease is low and endoscopy is the mainstay of differential diagnosis.

Innate immune mechanisms of colitis and colitis-associated colorectal cancer

The innate immune system provides first-line defences in response to invading microorganisms and endogenous danger signals by triggering robust inflammatory and antimicrobial responses. However, innate immune sensing of commensal microorganisms in the intestinal tract does not lead to chronic intestinal inflammation in healthy individuals, reflecting the intricacy of the regulatory mechanisms that tame the inflammatory response in the gut. Recent findings suggest that innate immune responses to commensal microorganisms, although once considered to be harmful, are necessary for intestinal homeostasis and immune tolerance. This Review discusses recent findings that identify a crucial role for innate immune effector molecules in protection against colitis and colitis-associated colorectal cancer and the therapeutic implications that ensue.

Environmental risk factors in inflammatory bowel diseases. Investigating the hygiene hypothesis: a Spanish case-control study

OBJECTIVE

Environmental factors have been implicated in the etiology of inflammatory bowel disease (IBD), but evidence for the hygiene hypothesis is unclear. We investigated the relationship between early-life infection-related exposures and risk of IBD.

PATIENTS AND METHODS

A hospital-based case-control study was carried out. A total of 124 cases of Crohn's disease (CD) and 146 of ulcerative colitis (UC) were compared with 235 and 278 well-matched control subjects, respectively. A multi-item questionnaire on familial history of IBD, childhood circumstances and familial socioeconomic status was carried out.

RESULTS

In a multivariate model, living in urban areas (odds ratio (OR) 4.58 (95% CI 2.17-10)), high educational level (OR 1.83 (95% CI 14-2.95)) and social status (OR 1.68 (95% CI 1.2-2.35)) were risk factors for CD, whereas childhood respiratory infections (OR 0.35 (95% CI 0.23-0.52)) and gastroenteritis (OR 0.55 (95% CI 0.36-0.85)) were protective factors. Living in urban areas (OR 4.6 (95% CI 2.29-9.9)), a high educational level (OR 10.3 (95% CI 2.54-42.1)) and social status (OR 2.042 (95% CI 1.31-3.17)) were also risk factors for UC, whereas respiratory infections (OR 0.42 (95% CI 0.29-0.6)) and gastroenteritis (OR: 0.6 (95% CI 0.42-0.86)) were protective factors. Appendectomy (OR 0.173 (95% CI 0.06-0.52)) and current smoking (OR 0.75 (95% CI 0.59-0.96)) were also protective for UC.

CONCLUSION

These results further support the hypothesis that better living conditions during childhood are associated with an increased risk for IBD, and reinforce the negative association between smoking and appendectomy and the risk of UC.

Editorial: Antibiotics earlier, IBD later?

Increasing evidence accumulates for a role of environmental factors in the onset of inflammatory bowel diseases (IBD). Among them, factors that might disturb the gut microflora hold an important place. As such, antibiotics deserve a special attention, and a possible association between their use, particularly during childhood, and the development of IBD, has been assessed by several authors since 1987. Results, conclusions, and possible impact of their observations, as well as perspectives for the future, are discussed here, in view of the article published in this issue of the Journal by Shaw et al.

Alteration of the murine gut microbiota during infection with the parasitic helminth Heligmosomoides polygyrus

BACKGROUND

In a murine model of inflammatory bowel disease (IBD), treatment of colitis in IL-10 gene-deficient mice with the parasitic helminth Heligmosomoides polygyrus ameliorates colonic inflammation. The cellular and molecular mechanisms driving this therapeutic host response are being studied vigorously. One proposed mechanism is that H. polygyrus infection favors the outgrowth or suppression of certain bacteria, which in turn help modulate host immunity.

METHODS

To quantify the effect of H. polygyrus infection on the composition of the gastrointestinal (GI) tract microbiota, we conducted two independent microbial ecology analyses of C57BL/6 mice. We obtained and analyzed 3,353 bacterial 16S rRNA encoding gene sequences from the ileum and cecum of infected and uninfected mice as well as incective H. polygyrus larvae at the outset of the second experiment and adult worms taken directly from the mouse duodenum at the end of the second experiment.

RESULTS

We found that a significant shift in the abundance and relative distribution of bacterial species in the ileum of mice is associated with H. polygyrus infection. Members of the bacterial family Lactobacillaceae significantly increased in abundance in the ileum of infected mice reproducibly in two independent experiments despite having different microbiotas present at the outset of each experiment.

CONCLUSIONS

These data support the concept that helminth infection shifts the composition of intestinal bacteria. The clinical consequences of these shifts in intestinal flora are yet to be explored.

Probiotics and the gut microbiota in intestinal health and disease

The use of probiotics is increasing in popularity for both the prevention and treatment of a variety of diseases. While a growing number of well-conducted, prospective, randomized, controlled, clinical trials are emerging and investigations of underlying mechanisms of action are being undertaken, questions remain with respect to the specific immune and physiological effects of probiotics in health and disease. This Review considers recent advances in clinical trials of probiotics for intestinal disorders in both adult and pediatric populations. An overview of recent in vitro and in vivo research related to potential mechanisms of action of various probiotic formulations is also considered.

Geographical variation of Crohn's disease residual incidence in the Province of Quebec, Canada

Background

Crohn's disease (CD) is clinically expressed as a chronic affection of the gastrointestinal tract currently known to have a multifactorial etiology involving a complex pathophysiological host response modulated by genetic susceptibilities, demographic determinants and environmental factors. With more than 20 cases per 100,000 person-years, the province of Quebec, Canada is among regions of the world with highest reported occurrence of CD in relation to other places where comparable estimates are available. This ecological study was designed to provide a medium-scale spatial exploration of CD incidence after accounting for the influence of known population and regional determinants. Health records of consulting patients in southern Quebec were compiled from 1995 to 2000 and used to estimate age and sex standardized rates per health area (n = 156). Various statistical models taking into account the regional effect of Jewish ethnicity, aboriginal ancestry, material deprivation, prescription for oral contraceptives, reportable enteric infection incidence, smoking as well as latitude and longitude locations were fitted.

Results

The final regression model presented a coefficient of determination of 22.8% and there was evidence of an eastern trend in the residual incidence (p = 0.018). Overall, the smoothed residual incidence presented a heterogeneous spatial pattern with evidence of patches (multiple health areas) of high, low and contrasting values. Health areas with most extreme incidence residuals where also distributed over the whole province including one area in the metropolitan area of Montreal and others in surrounding areas.

Conclusions

These findings suggest that known populational and regional factors derived through census information only explain a limited fraction of the geographical variation of CD incidence and lead to speculate that the effects of these factors may be incompletely captured (imperfect construction of proxy variables) or that other important factors remain unmeasured. In this view, markers of genetic profiles of homogeneous sub-populations, and other factors linked to agroenvironmental microbial exposure should be further investigated. Once accounting for known factors, it would also be worth comparing adjacent geographical areas demonstrating abrupt changes in residual incidence rates to further explore effect linked to regional factors from those resulting from various reporting systems.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: host-microbe interactions in the gut: target for drug therapy, opportunity for drug discovery

The commensal microbiota, most of which resides in the gut, is an environmental regulator of mucosal and systemic immune maturation. Epidemiological studies suggest that changes in the microbiota may represent a link between a modern lifestyle and risk of certain immuno-allergic diseases. This suggests that the microbiota is an appropriate target for therapy or prophylaxis, the rationale for which is addressed here using inflammatory bowel disease as an example. It is also evident from comparative studies of germ-free and conventionally colonized animals that the microbiota is a source of regulatory signals for full development of the host. In some instances these signals have been defined molecularly, and may be suitable for exploitation in novel drug discovery. Most of the versatile drugs in common usage today were derived originally from living matter in the wider environment; could it be time to mine new drugs from microbial-derived signalling molecules in the inner environment of the gut? Several examples illustrate the potential of the gut microbiota as a rich repository from which bioactives with immunological impact can be mined, and translated to human health care or to animal husbandry.

Emerging drugs to treat Crohn's disease

IMPORTANCE OF THE FIELD

Inflammatory bowel diseases are chronic inflammatory diseases that comprise of two forms - Crohn's disease (CD) and ulcerative colitis (UC) - characterized by aberrant responses to luminal bacteria in genetically susceptible individuals. Whereas inflammation is limited to the large intestine in patients with UC, CD can affect all parts of the gastrointestinal tract. During disease exacerbations, pharmacological or surgical intervention is usually needed to re-establish remission; however, current therapeutic interventions cannot cure CD. As a subgroup of patients with CD will not be able to remain in remission with available drugs or suffer from side effects, new therapeutic strategies are needed.

AREAS COVERED IN THIS REVIEW

This review focuses on emerging drugs in the treatment of CD and reviews data on their efficacy and safety. An extensive review of the available literature was undertaken using MEDLINE to identify relevant studies.

WHAT THE READER WILL GAIN

The reader will learn about current therapeutic strategies in patients with CD and gain insights into emerging new drugs.

TAKE HOME MESSAGE

As modification of the clinical course of CD becomes the therapeutic paradigm, potential future treatments have to induce mucosal healing in order to prevent long-term complications. New biologics show promising results.

Mucosal immunology, eosinophilic esophagitis, and other intestinal inflammatory diseases

The gastrointestinal mucosa constitutes the largest host-environment interface of the body. It uses both innate and adaptive immune mechanisms to provide protection from the diverse onslaught of foods, microbes, and other ingested products. The innate immune system is genetically encoded and evolutionarily ancient, possesses no memory, and lacks diversity. In contrast, the adaptive immune system is quite diverse, develops memory, and undergoes expansion after stimulation. The gastrointestinal mucosa is charged with the difficult task of mounting protective responses against invading microorganisms while simultaneously maintaining an overall state of nonresponsiveness or tolerance to innocuous substances, such as commensal bacteria and food antigens. Perturbation or malfunction of these complex protective mechanisms results in diseases, such as inflammatory bowel diseases, celiac disease, or eosinophilic gastrointestinal diseases.

Epigenetic maturation in colonic mucosa continues beyond infancy in mice

Monozygotic twin and other epidemiologic studies indicate that epigenetic processes may play an important role in the pathogenesis of inflammatory bowel diseases that commonly affect the colonic mucosa. The peak onset of these disorders in young adulthood suggests that epigenetic changes normally occurring in the colonic mucosa shortly before adulthood could be important etiologic factors. We assessed developmental changes in colitis susceptibility during the physiologically relevant period of childhood in mice [postnatal day 30 (P30) to P90] and concurrent changes in DNA methylation and gene expression in murine colonic mucosa. Susceptibility to colitis was tested in C57BL/6J mice with the dextran sulfate sodium colitis model. Methylation specific amplification microarray (MSAM) was used to screen for changes in DNA methylation, with validation by bisulfite pyrosequencing. Gene expression changes were analyzed by microarray expression profiling and real time RT-PCR. Mice were more susceptible to chemically induced colitis at P90 than at P30. DNA methylation changes, however, were not extensive; of 23 743 genomic intervals interrogated, only 271 underwent significant methylation alteration during this developmental period. We found an excellent correlation between the MSAM and bisulfite pyrosequencing at 11 gene associated intervals validated (R(2) = 0.89). Importantly, at the genes encoding galectin-1 (Lgals1), and mothers against decapentaplegic homolog 3 or Smad3, both previously implicated in murine colitis, developmental changes in DNA methylation from P30 to P90 were inversely correlated with expression. Colonic mucosal epigenetic maturation continues through early adulthood in the mouse, and may contribute to the age-associated increase in colitis susceptibility. Transcript Profiling: Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo/), accession numbers: GSE18031 (DNA methylation arrays), GSE19506 (gene expression arrays).