Inflammatory bowel disease: progress and current concepts of etiopathogenesis

Over the past few years, none of the numerous conditions that are grouped under the broad designation of 'chronic inflammatory or autoimmune disorders' has undergone as much scientific and clinical progress as the two main forms of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC). Progress has occurred in all major areas relevant to IBD pathogenesis, which include the external environment, genetics, microbial factors, and the immune system. This review presents an update on the specific major advances that have occurred in each of these four areas, briefly discusses the therapeutic implications of the observed progress, and points out the additional work that needs to be accomplished in the next few years to reach a full understanding of IBD etiopathogenesis.     

Review: Inflammatory bowel disease in India: challenges and opportunities

Evidence is emerging that inflammatory bowel diseases (IBDs) are becoming increasingly prevalent in developing countries, altering the previously held view that these were diseases of the West. Within this is a substantial increase in the burden of this disease in India, a matter of great importance to the country itself as well as in furthering our understanding of the disease. There is comparatively less data on this, both from the epidemiological standpoint as well as on disease pathogenesis in this particular cohort and is very much a subject matter of evolving understanding and research. This article aims to look at the changing global distribution of the disease and its implications. The Indian disease phenotype, and the aetiology of disease development will also be addressed with particular focus on differing pathogenetic processes in the Indian subpopulation, with consideration of what clues may be offered by the increasing incidence of the disease in this developing nation. Available evidence will be evaluated with the objective of providing a comprehensive overview of the development of IBD in India.     

Management of inflammatory bowel disease in adults

Optimal care of the inflammatory bowel diseases, Crohn's disease and ulcerative colitis, requires a broad understanding of disease pathophysiology and therapeutic alternatives. The goals of therapy are accurate diagnosis and timely treatment to both induce and maintain a clinical remission and improve patient quality of life. Most patients can be adequately treated using a combination or aminosalicylates, antibiotics, and corticosteroids, though many patients with Crohn's disease will require immunomodulators, such as azathioprine or 6-mercaptopurine. The development of novel biologic therapies, particularly infliximab, have dramatically improved our ability to medically manage more severe Crohn's disease and ulcerative colitis patients. This review will focus on the medical management of inflammatory bowel disease in adults.     

Progression of inflammatory bowel disease in China

The epidemiology and phenotype of inflammatory bowel disease (IBD) in the Chinese population is not well-known. We performed a comprehensive search of the Chinese biomedical literature database from 1989 to 2007 using the following key words: inflammatory bowel disease (IBD), ulcerative colitis (UC), Crohn's disease (CD). The investigation of hospitalized IBD patients from 1990 to 2003 was also carried out in 23 medical centers of 11 cities over China. There are some notable epidemiological and phenotypical differences between Chinese IBD and Caucasian IBD, including a lack of familial clustering, male predominance, a relatively later onset of the illness with no second peak age occurrence after 50 years old, a milder clinical course, less extra-intestinal manifestations and complications, and less fistulous and peri-anal complications in Chinese CD. The data indicate an increased incidence of IBD in China with many complicated clinical problems, which offers potential opportunities to study the disease prospectively and identify the etiological factors, leading also to the better management of this disease in China.     

Inflammatory bowel disease: dogmas and heresies

Perception of a disease state by the practising physician is based on how easily the diagnosis can be made and how predictable the outcome of the chosen therapy is. The academic investigator perceives the same disease based on how well its cause and mechanism are understood, and how rational pathophysiology-based treatments are. Because of incomplete knowledge, neither the practising physician nor the academic investigator are comfortable in dealing with inflammatory bowel disease, and both seek help in the dogmas and heresies inevitably associated with chronic disease of unknown aetiology.     

Microbiome and metabolome in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease of unknown etiology, involving complex interactions between the gut microbiome and host immune response. The microbial dysbiosis is well documented in IBD and significantly influences the host metabolic pathways. Thus, a metabolomic fingerprint resulting from the influence of gut dysbiosis in IBD could aid in assessing the disease activity. PubMed, Medline, Science Direct, and Web of Science were searched for studies exploring the association between microbiome and metabolome in IBD patients in the last 5 years. Additionally, references of cited original articles and reviews were further assessed for relevant work. We provide a literature overview of the recent metabolomic studies performed on patients with IBD. The findings report alterations in the metabolite levels of these patients. We also discuss the gut dysbiosis observed in IBD and its influence on host metabolic pathways such as lipids, amino acids, short-chain fatty acids, and others. IBD, being a chronic idiopathic disease, requires routine monitoring. The available non-invasive markers have their limitations. The metabolite changes account for both dysbiosis and its influence on the host's immune response and metabolism. A metabolome approach would thus facilitate the identification of surrogate metabolite markers reflecting the disease activity.     

Visualising E-selectin in the detection and evaluation of inflammatory bowel disease

Background—Vascular endothelial E-selectin expression is induced by proinflammatory cytokines andcontributes to accumulation of leucocytes in tissues.
Aims—To investigate the role ofE-selectin in inflammatory bowel disease (IBD).
Methods—E-selectin expression wasassessed in patients with ulcerative colitis and Crohn's disease bymeasuring the concentration of circulating soluble E-selectin(sE-selectin) using ELISA, by immunohistochemistry of colonic biopsyspecimens, and by abdominal immunoscintigraphy after injectingradiolabelled F(ab')₂ fragment of a monoclonalanti-E-selectin antibody. The value of scintigraphy usinganti-E-selectin was judged by a prospective comparative study ofautologous leucocyte scanning and E-selectin antibody scanning in 17 patients with IBD.
Results—Circulating sE-selectin waselevated in patients with clinically active disease. Tissue expressionof E-selectin was enhanced in patients with active inflammation, withweak or absent expression in inactive disease and healthy controls.In-111 labelled anti-E-selectin scintiscans were compared with Tc-99mlabelled leucocyte scans performed 24 hours earlier. Twelve patientshad areas of active inflammation on leucocyte scan while 11 patients had positive E-selectin scans. The results of the two scans were concordant in 14 patients, with those positive for both (10/17) showingsimilar disease localisation and extent.
Conclusions—Tissue E-selectinand circulating sE-selectin are increased during active inflammatorybowel disease. Anti-E-selectin imaging with radiolabelled monoclonalantibody identified areas of inflammation in Crohn's disease andulcerative colitis. The technique should prove useful clinically foridentifying the site and extent of disease.

Keywords:E-selectin; inflammatory bowel disease; Crohn'sdisease; ulcerative colitis

     

Genetics of inflammatory bowel diseases: A comparison between Western and Eastern perspectives

Inflammatory bowel disease (IBD) is a chronic relapsing intestinal inflammatory disorder with unidentified causes. Currently, studies indicate that IBD results from a complex interplay between various genetic and environmental factors that produce intestinal inflammation. However, these factors may differ for Asians and Caucasians. Thus, differences in epidemiology, genetic variants, and clinical phenotypes of IBD have been observed between the two populations. Understanding the discrepancies between data from populations with different genetic backgrounds and environmental factors may reveal fundamental aspects of IBD pathogenesis. Accordingly, this review will summarize the current knowledge of IBD genetics studied in Asian countries and compare it with that from Western countries, with special focus on innate bacterial sensing, autophagy, and the interleukin‐23 receptor‐T helper cell 17 pathway. The epigenetic nature of IBD pathogenesis as well as the pharmacogenetics related to the use of immunomodulators will also be briefly covered.     

Diagnostic misclassification reduces the ability to detect linkage in inflammatory bowel disease genetic studies.

BACKGROUND: Linkage data have now identified several inflammatory bowel disease (IBD) susceptibility loci but these data have not been consistently replicated in independent studies. One potential explanation for this is the possibility that patients enrolled in such studies may have been erroneously classified with respect to their diagnosis. AIMS: To determine the rate and type of misclassification in a large population of individuals referred for participation in an IBD genetics study and to examine the effect of diagnostic misclassification on the power to detect linkage. METHODS: The medical records of 1096 patients entered into an IBD genetics programme were reviewed using standardised diagnostic criteria. The original patient reported diagnoses were changed, if necessary, based on review, and the reasons for the change in diagnosis were recorded. To evaluate the effect of misclassification on linkage results, simulations were created with Gensim and analysed using Genehunter to evaluate a model for IBD inheritance. RESULTS: Sixty eight of 1096 (6.2%) individuals had a change in diagnosis from that originally reported. The majority of changes were patients with either Crohn's disease or ulcerative colitis who were determined not to have IBD at all. The principal reasons for changes to the original diagnosis were discordance between the patients' subjective reports of diagnosis and actual clinical history, endoscopic, or pathological results; a change in disease pattern over time; and insufficient information available to confirm the original diagnosis. A 10% misclassification rate resulted in 28.4% and 40.2% loss of power to detect a true linkage when using a statistical model for a presumed IBD locus with lambda(s) values of 1.8 and 1.3, respectively. CONCLUSIONS: Diagnostic misclassification occurs in patients enrolled in IBD genetic studies and frequently involves assigning the diagnosis of IBD to non-affected individuals. Even low rates of diagnostic misclassification can lead to significant loss of power to detect a true linkage, particularly for loci with modest effects as are likely to be found in IBD.     

The risk of inflammatory bowel disease flares after fecal microbiota transplantation: Systematic review and meta-analysis

Several studies have suggested worsening in inflammatory bowel disease (IBD) activity following fecal microbiota transplantation (FMT). We aimed to assess the risk of worsening in IBD activity following FMT. An electronic search was conducted using MEDLINE (1946-June 2016), EMBASE (1954-June 2016) and Cochrane Central Register of Controlled Trials (2016). Studies in which FMT was provided to IBD patients for IBD management or (Clostridium difficile infection) CDI treatment were included. The primary outcome was the rate of worsening in IBD activity. Results: Twenty-nine studies with 514 FMT-treated IBD patients were included. Range of follow up was 4 weeks to 3 y. The pooled rate of IBD worsening was 14.9% (95% CI 10–21%). Heterogeneity was detected: I2 D 52.1%, Cochran Q test D 58.1, p D 0.01. A priori subgroup analyses were performed. Although not significant, the pooled rate of worsening in IBD activity following FMT for CDI (22.7% (95% CI: 13–36%)) was higher compared with FMT for IBD (11.1% (95% CI 7–17%)). Rates of worsening in IBD after lower GI FMT delivery revealed a higher rate of worsening in IBD activity (16.5% (95% CI: 11–24%)) compared with upper GI delivery (5.6% (95% CI: 2–16%)). Rates of worsening in high quality studies and randomized controls trials (RCTS) suggested a marginal risk of worsening in IBD activity (4.6%, (95% CI: 1.8–11%). Rates of IBD worsening are overall marginal across high quality RCTS. It is unknown if the FMT itself led to the worsening of IBD in this small fraction or if this represents alternative etiologies.     

Comparison of clinical characteristics and management of inflammatory bowel disease in Hong Kong versus Melbourne

Background and Aim: Inflammatory bowel disease (IBD), common in Melbourne, was rare but is now increasing in incidence in Hong Kong (HK). To investigate whether these are the same diseases in the West and East, potential causes of changing incidence, and to plan resource needs, an appreciation of clinical characteristics in contrasting populations is essential. Methods: Disease characteristics were collected from prospectively populated IBD databases in two specialist centers in Melbourne, Australia and HK. Results: Of 795 patients (Crohn's disease [CD] : ulcerative colitis [UC] Melbourne 272:159 and HK 161:203), the age of diagnosis was higher, there were proportionally more male patients with CD but no UC sex difference, fewer patients were current or ex‐smokers (CD 8% vs 50%; UC 17% vs 35%) and a family history of IBD was less common (2% vs 11%; P < 0.001) in HK compared to Melbourne. Stricturing and perianal CD were more common in HK (12% vs 6%; P < 0.001; and 29% vs 16%; P = 0.001, respectively). In HK for UC, more patients had extensive disease at diagnosis (42% vs 22%) but colectomy was less common (7% vs 20%; P < 0.001). In Melbourne there was greater steroid use at diagnosis and patients were more likely to receive an immunomodulator or anti‐tumor necrosis factor agent. Conclusions: IBD in HK was diagnosed at an older age, and had more complicated disease behavior than in Melbourne. Medical therapy, however, was less intense in HK. These differences may relate to real differences in disease or delayed diagnosis due to late presentation and less disease recognition in HK.     

Granulocyte,monocyte/macrophage apheresis for inflammatory bowel disease: The first 100 patients treated in Scandinavia

Objective. Selective leukocyte apheresis is a new type of non-pharmacological treatment for patients with active ulcerative colitis and Crohn's disease. Preliminary data have indicated that this type of therapy is safe and efficacious, and large sham-controlled studies are currently in progress. In Scandinavia, a substantial number of patients with chronic inflammatory bowel disease have already received leukocyte apheresis on a compassionate use basis and the aim of this study was to report the clinical outcome and adverse events in the first patients treated. Material and methods. Clinical details of the first consecutive 100 patients with inflammatory bowel disease treated with granulocyte, monocyte/macrophage (Adacolumn) apheresis in Scandinavia were prospectively registered. Median length of follow-up was 17 months, (range 5–30). Results. The study population comprised 52 patients with ulcerative colitis, 44 patients with Crohn's disease and 4 patients with indeterminate colitis. In 97 patients the indication for Adacolumn treatment was steroid-refractory or steroid-dependent disease. Clinical remission was attained in 48% of the patients with ulcerative colitis, and an additional 27% had a clinical response to the apheresis treatment. The corresponding figures for patients with Crohn's disease were 41% and 23%, respectively. Complete steroid withdrawal was achieved in 27 out of the 50 patients taking corticosteroids at baseline. Adverse events were reported in 15 patients and headache was most frequently reported (n=7). Conclusions. Granulocyte, monocyte/macrophage apheresis treatment seems to be a valuable adjuvant therapy in selected patients with refractory inflammatory bowel disease. The risk for toxicity or severe adverse events appears to be low.     

Proteomics and metabolomics in inflammatory bowel disease

Genome‐wide studies in inflammatory bowel disease (IBD) have allowed us to understand Crohn's disease and ulcerative colitis as forms of related autoinflammatory disorders that arise from a multitude of pathogenic origins. Proteomics and metabolomics are the offspring of genomics that possess unprecedented possibilities to characterize unknown pathogenic pathways. It has been about a decade since proteomics was first applied to IBD, and 5 years for metabolomics. These techniques have yielded novel and potentially important findings, but turning these results into beneficial patient outcomes remains challenging. This review recounts the history and context of clinical IBD developments before and after proteomics and metabolomics IBD in this field, discusses the challenges in consolidating high complexity data with physiological understanding, and provides an outlook on the emerging principles that will help interface the bioanalytical laboratory with IBD prognosis.     

The emerging global epidemic of paediatric inflammatory bowel disease – causes and consequences

Two decades ago, paediatric inflammatory bowel disease (IBD) drew only modest interest from the international paediatric community. Since then, dramatically globally increasing incidence rates have made childhood‐onset IBD a priority for most paediatric gastroenterologists. The emerging pandemia of paediatric IBD has fuelled a quest to identify the recent changes in early life exposures that could explain the increasing risk for IBD amongst today's children. Treatment of children with IBD should aim for symptom control but should also target restoration of growth and prevention of pubertal delay. The paediatric IBD phenotype seems to be characterized by more extensive disease location, and some comparative studies have suggested that childhood‐onset IBD also represents a more severe phenotype than the adult‐onset IBD form. In this review, we analyse recent global incidence trends of paediatric IBD. We present an update on the known and suggested risk factors that could explain the emerging global epidemia of paediatric IBD. We also draw attention to differences in treatment between children and adults with IBD. Finally, we highlight latest follow‐up studies that question the proposed dynamic and aggressive nature of childhood‐onset IBD.     

Inflammatory bowel disease

Abstract

Scandinavian researchers have contributed to the present understanding of inflammatory bowel disease (IBD). Important epidemiological data and family risk factors have been reported from all the Nordic countries, original twin studies mainly from Denmark and Sweden, and relationships to cancer and surgery mostly from Sweden. In collaboration with the industry, development of medical compounds was for a long time in the front line of international research, and the Scandinavian countries participated in the clinical breakthrough of biologic treatment. At present, many Nordic centers are working in the forefront of IBD research. An increasing number of young investigators have entered the scene along with the extended distribution of University clinics and research laboratories in these countries. This presentation of IBD gives a brief overview in the fields of clinical epidemiology and molecular biology. Many areas are covered by International collaborations with partners from Nordic centers. IBD was a topic focused by the founders of Scandinavian Journal of Gastroenterology. After 50 years one may state that the journal’s history reflects important pieces of scientific knowledge within these diseases. The early scope of Johannes Myren for IBD was shown through his work in the original World Association of Gastroenterology (OMG), and after 50 years we can clearly support the view that global perspectives in IBD are increasingly important.     

Current status and future perspectives of leukocytapheresis for inflammatory bowel disease

Ulcerative colitis (UC) and Crohn's disease (CD) comprise the idiopathic inflammatory bowel diseases (IBD) of the gut. The etiology of IBD is poorly understood, but an autoimmune disturbance has been suggested to play an important role in this incurable disease. Extracorporeal leukocytapheresis (CAP) is an additional adjunct for IBD patients refractory to other conventional therapies, including steroids. The primary aim of CAP should be to suppress such unwanted immunological response by removing circulating inflammatory cells from the blood stream. The first decade has been passed since CAP was approved by Japanese social health insurance policy. It is therefore now an appropriate opportunity to upgrade and summarize our current understandings and/or future perspectives of this unique non-pharmacological and non-surgical strategy for IBD patients. According to several clinical and basic research reports, an early introduction of CAP should produce higher efficacy as compared with CAP applied sometime after a clinical relapse. Likewise, CAP therapy adjusted to patients' body-weight as well as two treatment sessions per week (intensive regimen) should benefit the efficacy rate. The etiology of IBD is not fully elucidated yet. As a result, the major therapeutic strategies in the Western world have been immunosuppressive therapy, including biologics. CAP is an unusual treatment modality for IBD because it seems to have both effectiveness and safety, which should generally be balanced in this type of illness. We now have to develop future strategies with and without combining biologics to improve the quality of life of IBD patients.