Causes Of IBD Research Articles

IDENTIFYING THE ROLE OF ACINETOBACTER CALCOACETICUS IN DRIVING INTESTINAL INFLAMMATION

Abstract BACKGROUND Inflammatory bowel disease (IBD) is a life-long condition characterized by chronic inflammation of the gastrointestinal tract. Among the potential causes of IBD, the gut microbiota has been implicated in perpetuating inflammation. Analysis of the IBD Transcriptome and Metatranscriptome Meta-Analysis (IBD TaMMA) database revealed that Acinetobacter calcoaceticus is one of the top 10 highest elevated bacteria in Crohn’s’ disease patients. Acinetobacter are well-characterized for their antibiotic resistance, but little is known about their interaction with the gut. We hypothesize that A. calcoaceticus colonizes the gut and promotes intestinal inflammation. MATERIALS & RESULTS We grew commercially available and clinical isolates of A. calcoaceticus in vitro with stressors found in the gut. All strains grew in a range of pHs (4-7), osmolarity (0.1-1 M NaCl), ethanol (1- 5%) and hydrogen peroxide (0.05-0.1%); indicating that A. calcoaceticus is well-adapted to withstand the harsher conditions of the gastrointestinal tract. To further investigate the ability of A. calcoaceticus to colonize the gut, we utilized Caenorhabditis elegans as a model. All A. calcoaceticus strains colonized the nematode's gut. We likewise found that all A. calcoaceticus strains colonized human stool-based bioreactors; suggesting that A. calcoaceticus can colonize the gastrointestinal tract. To identify whether A. calocaceticus stimulated inflammation, we incubated intestinal organoids and macrophages with live A. calcoaceticus or LPS derived from our A. calcaoceticus strains and found that both conditions stimulated pro-inflammatory cytokines. In order to confirm our in vitro findings, we oral gavaged adult BalbC mice with A. calcoaceticus and examined fecal levels using selective agar and qPCR. Acinetobacter was observed at low levels in the vehicle control mice and at high levels in our mice gavaged with A. calcoaceticus (average 9.9x 107 CFU); suggesting that A. calcoaceticus colonized the murine gut. To examine the ability of A. calcoaceticus to enhance inflammation, we oral gavaged mice with either a vehicle control (PBS) or A. calcoaceticus and the following day we administered 2,4,6-trinitrobenzene sulfonic acid (TNBS) to induce colitis. Mice treated with A. calcoaceticus and TNBS lost more weight and had worse histological scores than mice treated with vehicle control and TNBS; indicating A. calcoaceticus worsens intestinal inflammation. Finally, to expand the niche of Acinetobacter, we pre-treated mice with antibiotics and then subsequently administered bacteria and TNBS. In this model, A. calcoaceticus exacerbated inflammation above that of non-antibiotic treated mice. CONCLUSIONS These data show that A. calcoaceticus can promote intestinal inflammation and may be a contributing factor to the inflammation experienced by IBD patients.

Diet as an Optional Treatment in Adults With Inflammatory Bowel Disease: A Systematic Review of the Literature.

While the exact cause of IBD is unknown, there are a number of factors that are thought to contribute to its development, including environmental and genetic factors. While exclusive enteral nutrition (EEN) is a promising therapy for Crohn's disease (CD), it is not yet considered a first-line treatment. Additionally, the efficacy of EEN compared to corticosteroid treatment is still being investigated. EEN is suggested as a first-line therapy by which guidelines and in which age groups, as it may differ in pediatric and adult recommendations. Another finding was that dietary changes involving an increase in anti-inflammatory foods and decreased intake of foods high in inflammatory compounds are linked to a beneficial outcome both metabolically and microbiologically in patients with ulcerative colitis (UC) in remission. For relevant medical literature, we examined PubMed/Medline, the Cochrane Library, and Google Scholar as examples of medical databases. The articles were identified, evaluated, and eligibility applied, and nine publications were found. The finished articles investigated the role of several diet alternatives for patients with IBD. Some others have shown that following a normal low-fat diet may be effective in reducing the occurrence of subclinical colitis. The EEN and partial enteral nutrition (PEN) indicated no significant differences between both regimens, but both had good outcomes during active IBD. Other strict diets, such as the specific carbohydrate diet (SCD) versus the Mediterranean diet (MD), demonstrate excellent outcomes in patients with IBD. Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) dietary counseling improves gastrointestinal symptoms and quality of life in IBD patients. Based on the above, we concluded that more studies determining which component of the diet is not clear (proteins, carbs balanced) or diet types are required to establish a particular diet employed as a treatment intervention in these individuals.

Effect of gut microbiome alteration in inflammatory bowel disease

High morbidity rates are associated with inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. New studies have suggested that dysbiosis may play a role in the etiology of inflammatory bowel disease, although the cause of IBD remains unknown. Several disease pathologies, such as inflammatory bowel disease, have been associated with the intestinal microbiota, a metabolic organ with multiple physiological functions. This review summarizes the present level of knowledge regarding the impact of altered gut microbiota in inflammatory bowel disease, the mechanisms by which this occurs, and the potential significance of therapeutic methods based on gut microbiota in the prevention and treatment of IBD. It has been demonstrated that directly targeting the intestinal microbiota can treat both inflammatory bowel disease and colitis in humans and animals. To characterize the core microbiome associated with IBD and the underlying pathophysiology, however, additional research employing well-designed randomized control trials and animal models is required, as there are currently insufficient data and contradictory results from previous studies. The environment will influence the probiotic and prebiotic treatment for IBD.

Gut microbiota and inflammatory bowel disease.

Gut microbiota refers to the complex aggregation of microbes in gut, including bacteria, archaea, fungi, and viruses, and they exert marked influence on the host's health. Perturbations in the gut microbiota have been closely linked to initiation and progression of IBD, which has become a disease with accelerating incidence worldwide, but it remains to be thoroughly investigated how microbial involvement might contribute to IBD. In this review, we discuss the current research findings concerning alterations in the gut microbiota, trans-kingdom interaction between the members of the gut microbiota, their interactions with the immune system of host, their potential role in the IBD pathogenesis, and the relationship between gut microbiota and IBD. We hope to provide a better understanding of the causes of IBD and shed light on the development of microbiome-based therapeutic approaches, which might be a promising strategy to alleviate, manage, and eventually cure IBD. This article is categorized under: Infectious Diseases > Genetics/Genomics/Epigenetics Infectious Diseases > Molecular and Cellular Physiology.

Associations between participation in, intensity of, and time spent on leisure time physical activity and risk of inflammatory bowel disease among older adults (PA-IBD): a prospective cohort study

BackgroundInflammatory bowel diseases (IBDs) are diseases of the immune system that share some genetic and lifestyle-related predisposing factors. Increasing incidences have been reported in all age groups. Based on experimental studies suggesting a role of physical activity on intestinal inflammation, this study aimed to investigate the association between leisure time physical activity and the risk of IBD in older adults.MethodsThe study is a prospective cohort study using Danish registry data and questionnaire data from the Danish “Diet, Cancer and Health” cohort. The outcome IBD was defined as having at least two main diagnoses of Crohn’s disease or ulcerative colitis registered in the National Patient Registry from the period between December 1993 and May 1997 with an average follow-up of 25 years. Cox proportional hazard models were used to estimate hazard-ratios for IBD onset associated with being physically active and with levels of the metabolic equivalent of task (MET) hours/week of physical activity and hours/week spent on six types of physical activity. All analyses were adjusted for potential confounders. Furthermore, the analyses were stratified according to age-group, occupational physical activity, smoking, BMI and work status to test for effect modification.ResultsIn total, 54,645 men and women aged between 50 and 64 years were included, and of which there were 529 cases. When comparing physically active with inactive participants measured by MET hours/week there was no statistically significant difference in risk of IBD (0.89 [0.13; 6.27]), regardless of how participation was measured. Results did not indicate any dose-response effect when comparing quartile groups of MET hours/week (HR = 0.97 [0.76; 1.22], HR = 0.82 [0.64; 1.05] and HR = 0.83 [0.65; 1.07] or whether five of the six types of activities were compared with the lowest quartile as reference. For do-it-yourself-work, the third quartile of hours/week was associated with a higher risk of IBD compared to the second quartile of hours/week (HR = 1.44 [1.10; 1.90]. No effect modification was found.ConclusionsThere was no association between physical activity and risk of IBD when comparing physically active with inactive participants. Neither did the results indicate any dose-response effect when comparing quartile groups of MET hours/week with the lowest quartile as reference. Do-it-yourself work, however, appeared to be associated with a higher risk of IBD when comparing the third quartile with the second quartile of hours/week. The study has clinical relevance by its contribution to the explanatory field of the causes of IBD. However, the study has some limitations, and further research is needed to clarify associations between physical activity and risk of IBD.

Clostridium difficile infection and chronic inflammatory bowel disease.

Patients with IBD are at increased risk of developing Clostridium difficile (CD) infection and have worse outcomes, including higher rates of colectomy and death, and experience higher rates of recurrence. However, it is still not clear whether CD is a cause of IBD or a consequence of the inflammatory state and of intestinal dysbiosis. The association between IBD and CD may be due to different factors, such as drugs that are used for the treatment of IBD, including repeat courses of antibiotics, that might alter the intestinal flora and promote colonization, altered immune and nutritional status, frequent hospitalizations, and even genetic predisposition. It has been suggested that up to 20% of IBD flares were associated with testing positive for CD and retrospective studies demonstrated doubling of the infection incidence among patients with Crohn Disease, and a 3-fold increase among those with Ulcerative Colitis. They have also shown that the CD infection incidence among IBD patients is estimated as being 3-fold higher than that in the general population. Decreased intestinal microbial diversity along with an inadequate immune response is thought to play a causative role in the development of CD infection.

Susceptible Role of Saccharin Mixture in Induction of Inflammation Through Action on Interleukin-10 and its Receptor

Sodium cyclamate and saccharin mixture is a common artificial sweetener used as a food additive and it was found to be accompanied with increase relevance of inflammation including IBD. The causes of IBD are unknown, but many immune, genetic and environmental factors play a role as causative agents of that disease. The consumption of artificial sweeteners was related to the appearance of inflammation including IBD. The present study was aimed to evaluate the effect of sodium cyclamate and saccharin mixture as artificial sweeteners on immune system in albino mice through assessment of IL-10 cytokine and its receptor. Fifty male albino mice grouped into control group (n=20) receive only tap water and treated groups (n=30) received 60 mg/kg body weight sodium cyclamate and saccharin mixture in tab water for 12 weeks. Mice were sacrificed twice at the 6th and the 12th weeks. Collected blood measured low concentration of IL-10 cytokine by the sandwich ELISA. While, expression levels of IL-10R1 and IL-10R2 were assessed in colorectal tissue samples using Real time PCR. The results demonstrate significantly overexpression of IL-10R1 and IL-10R2 at 6th week than 12th week treated mice was recorded. Also, more congestion of RBCs, focal aggregation, focal necrosis, and focal infiltrations between glands in the lamina propria at 12th week treated group than 6th week treated group were observed. In conclusion, sodium cyclamate and saccharin mixture induced inflammation that may be risk for IBD by alteration in gene expressions of IL-10R1 and IL-10R2 in male albino mice.

Clinical Genomics for the Diagnosis of Monogenic Forms of Inflammatory Bowel Disease: A Position Paper From the Paediatric IBD Porto Group of European Society of Paediatric Gastroenterology, Hepatology and Nutrition.

It is important to identify patients with monogenic IBD as management may differ from classical IBD. In this position statement we formulate recommendations for the use of genomics in evaluating potential monogenic causes of IBD across age groups. The consensus included paediatric IBD specialists from the Paediatric IBD Porto group of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and specialists from several monogenic IBD research consortia. We defined key topics and performed a systematic literature review to cover indications, technologies (targeted panel, exome and genome sequencing), gene panel setup, cost-effectiveness of genetic screening, and requirements for the clinical care setting. We developed recommendations that were voted upon by all authors and Porto group members (32 voting specialists). We recommend next-generation DNA-sequencing technologies to diagnose monogenic causes of IBD in routine clinical practice embedded in a setting of multidisciplinary patient care. Routine genetic screening is not recommended for all IBD patients. Genetic testing should be considered depending on age of IBD-onset (infantile IBD, very early-onset IBD, paediatric or young adult IBD), and further criteria, such as family history, relevant comorbidities, and extraintestinal manifestations. Genetic testing is also recommended in advance of hematopoietic stem cell transplantation. We developed a diagnostic algorithm that includes a gene panel of 75 monogenic IBD genes. Considerations are provided also for low resource countries. Genomic technologies should be considered an integral part of patient care to investigate patients at risk for monogenic forms of IBD.

A39 NOVEL GAIN OF FUNCTION NON-RECEPTOR TYROSINE KINASE MUTATIONS ARE LINKED TO THE PATHOGENESIS OF VEOIBD

Abstract Background Very early-onset inflammatory bowel disease (VEOIBD) is an emerging global disease, that results in inflammation of the digestive tract. Severe forms of VEOIBD can be caused by mutations in a single gene (monogenic variants) and, can result in death. A candidate gene which codes for a non-receptor tyrosine kinase (nRTK) has recently been implicated as a monogenic cause of IBD (unpublished). Whole exome sequencing was performed in two unrelated children who presented with symptoms of IBD identifying two distinct de novo gain of function mutations (S550Y and P342T). Both mutations are located in the highly conserved region of the nRTK, and were predicted to have similar downstream effects. Furthermore, four other patients with a variety of adult-onset immune disorders have recently been identified with rare variants in the same gene (M450I, R42P, A353T, V433M, S550F) but, their potential gain of function status remains to be determined. Studies show that this nRTK is an essential mediator in inflammation. It is expressed in both intestinal epithelial and immune cells however, its role in infantile IBD is unclear. This protein is first activated by phosphorylation and is linked to activating downstream transcription factors such as ERK and JNK. All these target proteins play a meaningful role in intestinal inflammation in patients with IBD. Aims Since we identified P342T and S550Y to be gain of function, we wanted to determine if the new variants exhibit a similar downstream impact on target protein expression levels when compared with S550Y and P342T. We also wanted to identify if all variants can be rescued with a known nRTK inhibitor. It is hypothesized that the new variants are gain of function and that all variants can be rescued with the inhibitor. Methods Using western blot analysis, the activation of ERK, JNK and nRTK was compared between wildtype (WT) and mutants. This in vitro method helped identify the degree of activation. For the second part of the study, HEK293T cells were treated with inhibitor to test for a rescue of phenotypes via western blot analysis. Results Results show an increased activation of nRTK, ERK and JNK in all variants with S550Y and S550F having the highest activation. Furthermore, pharmacological inhibition using small molecular kinase inhibitors resulted in decreased activation of nRTK, ERK and JNK suggesting a rescue of phenotypes. Conclusions Characterizing the downstream functional impact of these nRTK variants is an important first step to determine if gain of function nRTK mutations drive IBD. With a rising prevalence of IBD worldwide, these findings may lead to the development of pharmacological nRTK inhibitors as a novel personalized therapeutic approach for these patients and possibly for the broader IBD population. Funding Agencies CIHR

Redefining the IBDs using genome-scale molecular phenotyping.

The IBDs, Crohn's disease and ulcerative colitis, are chronic inflammatory conditions ofthe gastrointestinal tract resulting from an aberrant immune response to enteric microbiota ingenetically susceptible individuals. Disease presentation and progression within and across IBDs, especially Crohn's disease, are highly heterogeneous in location, severity of inflammation and other phenotypes. Current clinical classifications fail to accurately predict disease course and response to therapies. Genome-wide association studies have identified >240 loci that confer riskof IBD, but the clinical utility of these findings remains unclear, and mechanisms by which thegenetic variants contribute to disease are largely unknown. In the past 5 years, the profiling ofgenome-wide gene expression, epigenomic features and gut microbiota composition in intestinal tissue and faecal samples has uncovered distinct molecular signatures that define IBD subtypes, including within Crohn's disease and ulcerative colitis. In this Review, we summarize studies in both adult and paediatric patients that have identified different IBD subtypes, which in some cases have been associated with distinct clinical phenotypes. We posit that genome-scale molecular phenotyping in large cohorts holds great promise not only to further our understanding of the diverse molecular causes of IBD but also for improving clinical trial design to develop more personalized disease management and treatment.

Sequence Analysis of TNFRSF13b, Encoding TACI, in a Patient with Very Early Onset Inflammatory Bowel Disease: a Case Report

Very early onset inflammatory bowel disease (VEO-IBD), IBD diagnosed before 6 years of age, frequently presents with increased severity, aggressive progression, and often poor response to conventional treatments. Although the cause of IBD is generally considered to be intestinal immune dysfunction induced by polygenic mutations and environment and other factors, VEO-IBD has a stronger genetic susceptibility specifically the neonatal- or infantile-onset IBD. Herein we report compound heterozygous mutations in the tumor necrosis factor receptor superfamily member 13b (TNFRSF13B) gene in a 3-year-old male that was admitted to our hospital with lasted jaundice, repeated fever and diarrhea in May 2014 at 2-month-old. He was diagnosed with VEO-IBD based on clinical, laboratory and histopathological examination. However, he was unresponsive to the conventional therapy, including the nutritional support therapy, antibiotic and immunosuppressive treatment, and surgical release of neonatal intestinal obstruction. Novel compound heterozygous mutations, c.[365G>A];[452C>T](p.[R122Q];[P151L]), were discovered in TNFRSF13B, encoding TACI, for this patient.

Debate session: So what causes inflammatory bowel disease? It's all in the environment.

The past decade has witnessed a revolution in our understanding of the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC). Significant strides have been made in our understanding of the genetic architecture of these complex diseases, yet the exact cause of IBD remains unclear.1 The relative contribution of genetic and non-hereditary factors in disease pathogenesis also remains to be well established. Considerable lines of evidence suggest that environmental factors may play a dominant role in the pathogenesis of IBD such that these diseases may even be considered “environmental” in origin.2, 3 First, despite significant progress through international collaborative genetic consortia, genetic polymorphisms explain very little of the occurrence of IBD.4, 5 In twin studies, summarized in an elegant review by Brant et al., even in monozygotic twins, the concordance of CD and UC remain only 30% and 15%, respectively, suggesting that genetics incompletely explain disease variance.6 Three large global pooled analyses from genetic consortia have increased the number of risk single nucleotide polymorphisms for CD and UC to 174 and 164 loci, respectively. However, all risk loci together explain only 13% and 8% of the variance of disease. In addition, each single nucleotide polymorphism itself confirms only modest elevated risks with odds ratio for most being between 1.02 and 1.32.7 Further, epidemiologic trends globally have demonstrated that there has been a 2–3 fold increase in the incidence of CD and UC between 1940 and 2010.8, 9 These findings have been demonstrated not just from population-based cohorts in North America and Europe but also from Asian populations where IBD was previously considered very rare.10 In addition, second-generation immigrants from families that have migrated from a region of low incidence to a high IBD incidence country have a risk of IBD that is similar to that of their country of residence and higher than that of their country of origin.11 The temporal changes in IBD incidence also parallel the many epidemiologic trends noted globally with decreasing consumption of dietary fiber, increased consumption of sugars, fats, and processed food, and changes in lifestyle and the external environment. Together, these factors strongly support that the environment plays an important role in the pathogenesis of IBD. Emerging data from prospective cohort studies in the United States and Europe have demonstrated an association between various environmental factors and risk of CD or UC.3 These include an association of higher incidence of CD with lower intake of dietary fiber,12 low vitamin D levels, nonsteroidal anti-inflammatory drug intake, and stress, while a higher intake of n-3 containing PUFA13 is associated with reduced risk of UC. These epidemiologic observations are also supported by various mechanistic studies demonstrating the biological plausibility of these associations exerting an influence on intestinal inflammation by alteration of the microbiome and/or immunologic responses. The final piece of evidence in support for IBD being an environmental disease is that changing behavior alone through either diet modification (exclusive enteral nutrition) or smoking cessation14 has been associated with an improvement in disease course like that observed with certain pharmacologic therapies. Thus, there is now a wealth of evidence from clinical observations, epidemiologic studies, and laboratory experiments that suggests a strong effect of the external environment on IBD pathogenesis and subsequent course.

Styrene maleic acid encapsulated raloxifene micelles for management of inflammatory bowel disease

BackgroundInflammatory bowel disease (IBD) comprises a group of disorders that manifest through chronic inflammation of the colon and small intestine. Although the exact cause of IBD is still unclear, dysfunctional immunoregulation involving overproduction of inflammatory cytokines such as TNF-α, and IL-6 have been implicated in pathogenesis. Current therapy relies on immunosuppression, cytotoxic drugs, and monoclonal antibodies against TNF-α. These classes of drugs have severe side-effects, especially when used for long duration. Our previous work with raloxifene, a selective estrogen receptor modulator, has shown that the drug, and to a greater extent its micellar formulation, has a significant suppressive effect on NF-κB, an essential immune-regulator. This finding directed the current work towards testing the anti-inflammatory and immunomodulatory effects of raloxifene using cell lines, as well as testing the potential use of the styrene maleic acid (SMA) micelles loaded with raloxifene (SMA-Ral) against dextran sulfate sodium (DSS) induced colitis in an in vivo model of IBD.ResultsTreatment of MCF-7 cells with TNF-α was shown to protect the cells from the cytotoxic effect of raloxifene (42 vs. 10% cell death, with TNF-α. Treating CaCo-2 cells with both free and SMA-Ral improved cell survival after exposure to 2% DDS with significantly higher protection with SMA-Ral. Treatment of U-937 with SMA-Ral and free-Ral resulted in down-regulation of TNF-α, IL-1β, IL-6, and MIP1α, with greater inhibition of the SMA-Ral, compared to free Ral. Balb/c mice treated with raloxifene and SMA-Ral showed weight gain at 14 days, compared to the control group (122, and 115% respectively). Treatment with raloxifene prevented DSS-induced diarrhea in 6/6 of free raloxifene treated mice and in 5/6 mice treated with SMA-Ral. Control group of DSS-treated mice showed average colon length of 7.4 cm compared to 13 cm in the control group. The average colon length was 12.3 and 11.5 cm for raloxifene and SMA-Ral treated groups, respectively. Furthermore, inflammatory cytokines such as IL-6 and TNF-α were reduced in serum of animals treated with free-Ral and SMA-Ral.ConclusionsRaloxifene and its micellar formulation warrants further studies to understand their effect on the treatment of colitis.Graphical abstractSMA-Raloxifene preparation and its in vivo and in vitro effect on colitis

P178 Validation of the clinical utility of IFI16-based markers in IBD

Background: Although the exact cause of IBD remains unknown, available evidence suggests that an abnormal immune response against the intestinal microorganisms is responsible for the disease in genetically susceptible individuals. Recent advances in immunology and genetics have clarified that the innate immune response is as important as adaptive immunity in inducing gut inflammation in IBD patients. Significant alterations in the expression and function of pattern recognition receptors (PRRs), including the IFI16 protein, were indeed described in colonic mucosal biopsies from active ulcerative colitis (UC) patients versus healthy controls (Vanhove et al., Inflamm Bowel Dis 2015). We have recently extended these analyses to Crohn's disease (CD) patients (Caneparo et al., Inflamm Bowel Dis 2016). Furthermore, because we have previously demonstrated that IFI16 protein is a target for autoantibodies, this study aimed to evaluate its specific seroresponse in a large and heterogeneous cohort of patients with IBD. Methods: To date, we have measured anti-IFI16 antibodies (IgG and IgA subtypes) in the sera of 157 patients with IBD: 113 patients with CD and 44 patients with UC, prospectively harvested before and after therapy. The patient antibody statuses were qualitatively and quantitatively associated with disease phenotype and response to therapy, and compared to those for anti-GP2 antibodies. Results: In a cohort of patients undergoing Infliximab (IFX) treatment, we have recently observed significantly higher titers of anti-IFI16 IgG in both CD and UC patients compared with healthy controls. Anti-IFI16 IgA titers were also present in patients with CD. Finally, significant changes in anti-IFI16 IgG subtype titers after IFX therapy were demonstrated in patients with CD, which correlate with clinical remission. In the present study, we have extended this analysis to a larger IBD cohort including patients with therapy other than IFX. The results substantiate that anti-IFI16 autoantibody titers are significantly higher in IBD patients than in controls. Moreover, IgG and IgA titers correlate with different specific clinical features in CD patients. Conclusions: Our recent results have highlighted the importance of IFI16 in IBD pathogenesis showing that its de novo overexpression in the gut epithelial cells may lead to the development of specific autoantibodies (Caneparo et al., Inflamm Bowel Dis 2016). Furthermore, our recent results in a larger cohort of IBD patients substantiate our reasons to focus on the biological and clinical significance of the IFI16 protein and specific antibodies, and their clinical utility with the potential to ameliorate the diagnostic/prognostic stratification of IBD.

P-176 SHIP1 Deficiency in Human IBD

The causes of IBD are not fully known. Significant insights into the etiology of human IBD have come from Genome-Wide Association Studies (GWAS), which have identified more than 100 different inherited mutations that influence the risk of IBD in affected families. Only about 10% to 15% of all IBD adult patients have any of these genetic mutations. This means that risk factors for approximately 85% of IBD patients have yet to be defined. We have previously shown that mutation of SHIP1 leads to a Crohn's-like ileitis in mice. We hypothesized that loss of SHIP1 might potentially contribute to IBD in humans. SHIP1 expression was analyzed by qRT-PCR, Western blot, intracellular flow cytometry (icFlow) and RNAseq in-patient PBL. In order to determine if SHIP1/INPP5D deficiency might also contribute to human IBD, we analyzed SHIP1 expression in more than 100 adult IBD patients. We find that ∼15% of the adult IBD population demonstrates a profound degree of SHIP1 deficiency at the protein level (<10% of normal). However, both qRT-PCR and RNAseq analysis indicate these SHIP1-deficient patients have normal SHIP1 mRNA expression. Exome sequencing of the entire SHIP1/INPP5D gene in 8 separate SHIP1-deficient patients revealed no coding changes in the SHIP1/INPP5D gene that could account for the profound decrease in SHIP1 protein expression. Treatment of blood leukocytes with a proteasome inhibitor significantly increases SHIP1 protein expression in SHIP1 deficient patient PBL, but has the opposite effect in SHIP1-sufficient patients PBL. Flow cytometric analysis showed that SHIP1-deficient patients have a significant reduction in circulating CD4+ T cells, as do CD4CreSHIPflox/flox mice that have a selective ablation of SHIP1 expression in T lineage cells. In order to identify mutations or changes in gene expression at other loci that could adversely impact SHIP1 protein expression we performed RNAseq analysis on 10 separate SHIP1 deficient patients. Comparison of their transcriptomes to normal healthy controls indicates profound disruption of gene expression in SHIP1 deficient IBD patients. We also recently assessed disease severity in SHIP1 deficient IBD patients. We find that 63% of SHIP1-deficient CD patients have had surgical resection of their GI tract versus 23% in the SHIP1-sufficient cohort (P = 0.024) and have required on average 1.9 resections versus 0.3 in the SHIP1-sufficient CD cohort (P = 0.009). We also performed a computational drug screen that led to the identification of a novel SHIP1 agonist, K204. Using a human T cell model of SHIP1 protein deficiency, we show that K204 can significantly increase SHIP1 protein expression in intact cells. We find that a significant proportion of IBD patients have a profound reduction of SHIP1 expression. SHIP1 deficiency appears to have an adverse impact on disease progression as more than 60% of CD patients that are SHIP1-deficient require surgical resection of their GI tract, including multiple resections. We also find that SHIP1 protein is preferentially degraded by the proteasome system in SHIP1-deficient patients. Importantly, proteasome inhibitors and a novel SHIP1 agonist can partially restore SHIP1 protein expression suggesting a novel therapeutic approach in IBD.

TGF-β1 Signalling, Connecting Aberrant Inflammation and Colorectal Tumorigenesis

TGF-β1 is an anti-inflammatory cytokine recognised as a key regulator of immunological homeostasis and inflammatory responses. Furthermore, TGF-β1 is important for the regulation of cell growth, differentiation and apoptosis in a wide range of tissues including the intestinal epithelium. Reduced TGF-β1 activity is thought to be responsible for the development of autoimmune disorders in several pathological conditions, including inflammatory bowel disease [IBD]. Although the cause of IBD is not yet known, research has shown that a number of factors may be involved including environment, diet and genetics, as well as cytokine exposure. Importantly, IBD is also associated with an increased lifetime risk of developing colorectal cancer, which remains the fourth most common cancer worldwide, representing a significant therapeutic challenge. As functionally implicated in both maintenance of the immune response and tissue homeostasis in the colon, TGF-β1 signalling potentially sits at the crossroads between aberrant inflammation and colorectal tumorigenesis. Hence, the purpose of this paper is to review the evidence for cross talk between TGF-β1 signalling and pathways important for colorectal tissue homeostasis, with the emphasis on understanding how deregulation of TGF-β1 signalling contributes not only to aberrant inflammatory disease but also to colorectal tumour progression.

IBD—what role do Proteobacteria play?

The gastrointestinal microbiota has come to the fore in the search for the causes of IBD. This shift has largely been driven by the finding of genetic polymorphisms involved in gastrointestinal innate immunity (particularly polymorphisms in NOD2 and genes involved in autophagy) and alterations in the composition of the microbiota that might result in inflammation (so-called dysbiosis). Microbial diversity studies have continually demonstrated an expansion of the Proteobacteria phylum in patients with IBD. Individual Proteobacteria, in particular (adherent-invasive) Escherichia coli, Campylobacter concisus and enterohepatic Helicobacter, have all been associated with the pathogenesis of IBD. In this Review, we comprehensively describe the various associations of Proteobacteria and IBD. We also examine the importance of pattern recognition in the extracellular innate immune response of the host with particular reference to Proteobacteria, and postulate that Proteobacteria with adherent and invasive properties might exploit host defenses, drive proinflammatory change, alter the intestinal microbiota in favor of dysbiosis and ultimately lead to the development of IBD.

Epidemiology of inflammatory bowel disease

The incidence of IBD has either continued to increase or has stabilized at a high rate in most developed countries, whereas the incidence continues to rise in regions where IBD had been less common. The prevalence has continued to increase as a result of a combination of previously rising incidence and improved survival. Regardless of the exact prevalence, the burden of disease in North America and Europe is significant. Studying the patterns of geographic variation and age and gender distribution may yield important clues to the cause of IBD.

NUTRITIONAL CONSIDERATIONS IN INFLAMMATORY BOWEL DISEASES

Although many foods have been suggested to play a role in the cause of IBD, there are not yet definitive data to support diet as a cause of either CD or UC. Malnutrition is a common occurrence in IBD, and this must be considered in the treatment of these diseases. Nutritional support in IBD has limited use as primary therapy (Table 2). Even though parenteral and enteral nutrition have been associated with remission, relapse frequently occurs when normal food intake is resumed. Likewise, fistulae may resolve with aggressive, nutritional therapy, but they frequently recur with reinstitution of food. In short bowel syndrome caused by extensive intestinal resection performed in CD, parenteral nutrition provides an important mode of therapy. In addition, perioperative use of nutritional support may decrease the incidence of postoperative complications in patients who are malnourished. Nutritional support in pediatric patients with CD who have growth failure has been effective in stimulating growth.

Inflammatory bowel disease part I: Nature and pathogenesis

Once regarded as medical curiosities, ulcerative colitis and Crohn's disease have achieved a remarkable change in status recently and today are among the more compelling of all human illnesses. The cause(s) of inflammatory bowel disease (1131)) are not known. Genetic, environmental, microbial, and immunologic factors are involved, but the precise mechanisms are obscure. The incidence of ulcerative colitis is relatively stable, while Crohn's disease continues to increase in frequency. In 10% to 15% of patients, it is hard to differentiate between ulcerative colitis and Crohn's colitis; however, problems with diagnosis usually resolve with time and repeated examinations. In part I of his two-part monograph on IBD, Dr. Kirsner addresses the nature and pathogenesis of the disease. Increased study of ulcerative colitis and Crohn's disease in recent years has generated new knowledge regarding their etiology. Part I focuses on microbial, immunologic, and genetic mechanisms and the inflammatory processes involved in the disease. In part 11, which will be presented in next month's issue of Disease-a-Month, Dr. Kirsner deals with the clinical features, course, and management of IBD, based on the author's 55 years of experience with these problems and supplemented by critical examination of the recent (1988–1990) literature. Particular attention is directed to the symptoms and physical findings of ulcerative colitis and Crohn's disease, the laboratory, radiologic, endoscopic, and pathologic features, and the many systemic complications. The IBDs are mimicked by several enterocolonic infections and other conditions, making differential diagnosis necessary. Inflammatory bowel disease in children and the elderly conforms to conventional clinical patterns modified by the health circumstances of the respective age groups. Because the cause of IBD has not been established, current medical therapy is facilitative and supportive rather than curative. The principles of medical treatment are approximately the same for ulcerative colitis and Crohn's disease. Treatment emphasizes a program rather than a drug and also considers the individuality of the therapeutic response. A clearer understanding of dietary and nutritional needs, including hyperalimentation and electrolyte and fluid balance, aids treatment. Antidiarrheal and antispasmodic preparations and sedatives are prescribed for symptom relief. The bowel inflammation is controlled with sulfasalazine or the newer 5-amino salicylic acid (5-ASA) compounds, antibacterial drugs for complications of Crohn's disease and IBD, adrenocortical steroids, and the immunosuppressive compounds 6-mercaptopurine (6-MP), azathioprine, and cyclosporine, as determined in each patient. The surgical procedures available for treatment of ulcerative colitis include total proctocolectomy and ileostomy or ileoanal anastomosis. In Crohn's disease of the small bowel, the usual approach is intestinal resection and re-anastomosis. Strictureplasty is possible in some instances of stenotic intestinal disease. For treatment of Crohn's colitis, procedures include total proctocolectomy and ileostomy, subtotal colectomy and ileorectal anastomosis, and very occasionally, segmental resection of the large intestine. p ]Chronic IBD requires prolonged observation, periodic adjustments in therapy, and colonic and radiologic surveillance. The prognosis of ulcerative colitis and Crohn's disease is much improved over the years, but a cure has not yet been found, reemphasizing the need for further investigation of these challenging diseases.