Palmitoylation in Crohn’s disease: Current status and future directions

S-palmitoylation is one of the most common post-translational modifications in nature; however, its importance has been overlooked for decades. Crohn’s disease (CD), a subtype of inflammatory bowel disease (IBD), is an autoimmune disease characterized by chronic inflammation involving the entire gastrointestinal tract. Bowel damage and subsequent disabilities caused by CD are a growing global health issue. Well-acknowledged risk factors for CD include genetic susceptibility, environmental factors, such as a westernized lifestyle, and altered gut microbiota. However, the pathophysiological mechanisms of this disorder are not yet comprehensively understood. With the rapidly increasing global prevalence of CD and the evident role of S-palmitoylation in CD, as recently reported, there is a need to investigate the relationship between CD and S-palmitoylation. In this review, we summarize the concept, detection, and function of S-palmitoylation as well as its potential effects on CD, and provide novel insights into the pathogenesis and treatment of CD.     

Disease Pandemics and Major Epidemics Arising From New Encounters between Indigenous Viruses and Introduced Crops

Virus disease pandemics and epidemics that occur in the world’s staple food crops pose a major threat to global food security, especially in developing countries with tropical or subtropical climates. Moreover, this threat is escalating rapidly due to increasing difficulties in controlling virus diseases as climate change accelerates and the need to feed the burgeoning global population escalates. One of the main causes of these pandemics and epidemics is the introduction to a new continent of food crops domesticated elsewhere, and their subsequent invasion by damaging virus diseases they never encountered before. This review focusses on providing historical and up-to-date information about pandemics and major epidemics initiated by spillover of indigenous viruses from infected alternative hosts into introduced crops. This spillover requires new encounters at the managed and natural vegetation interface. The principal virus disease pandemic examples described are two (cassava mosaic, cassava brown streak) that threaten food security in sub-Saharan Africa (SSA), and one (tomato yellow leaf curl) doing so globally. A further example describes a virus disease pandemic threatening a major plantation crop producing a vital food export for West Africa (cacao swollen shoot). Also described are two examples of major virus disease epidemics that threaten SSA’s food security (rice yellow mottle, groundnut rosette). In addition, brief accounts are provided of two major maize virus disease epidemics (maize streak in SSA, maize rough dwarf in Mediterranean and Middle Eastern regions), a major rice disease epidemic (rice hoja blanca in the Americas), and damaging tomato tospovirus and begomovirus disease epidemics of tomato that impair food security in different world regions. For each pandemic or major epidemic, the factors involved in driving its initial emergence, and its subsequent increase in importance and geographical distribution, are explained. Finally, clarification is provided over what needs to be done globally to achieve effective management of severe virus disease pandemics and epidemics initiated by spillover events.     

Smoking increases the risk of extraintestinal manifestations in Crohn's disease

AIM: To demonstrate a high prevalence of extraintestinal manifestations (EIMs) in a prospective population-based cohort of inflammatory bowel disease (IBD) patients at first diagnosis as well as during the early course of the disease.METHODS: EIMs are common in patients with IBD. Data on the frequency of EIMs have mostly been assessed in patients from tertiary centers; however, data about the prevalence of EIMs at first diagnosis as well as factors influencing their incidence during the early course of disease from prospective population-based cohorts are scarce. We present data of patients of our population-based “Oberpfalz cohort” (Bavaria, Germany) from first diagnosis (up to 3 mo after first diagnosis) as well as during the early course of the disease. Possible risk factors were assessed by calculating the relative risk (RR) as well as using logistic regression analysis.RESULTS: In total, data of 257 newly diagnosed patients with IBD were evaluated [161 Crohn’s disease (CD), 96 ulcerative colitis (UC)]. Median duration of follow-up was 50 mo after first diagnosis. In 63.4% of all patients (n = 163), an EIM was diagnosed at any point during the observation period. At first diagnosis, patients with CD had a significantly increased risk of an EIM [n = 69 (42.9%)] compared with UC patients [n = 21 (21.9%); P < 0.001; RR = 1.96; 95%CI: 1.30-2.98]. Active smoking increased the risk of CD patients developing an EIM during the early course of the disease, but notably not of UC patients (P = 0.046; RR = 1.96; 95%CI: 1.01-3.79). In addition, using logistic regression analysis, the need for IBD-related surgery and a young age at first diagnosis were identified as risk factors for the development of an EIM in CD patients. No association with EIMs was found for the factors sex, localization of the disease and positive family history of IBD. In contrast, no key factors which increased the risk of development of an EIM could be identified in UC patients.CONCLUSION: We found a high prevalence of EIM in this cohort at first diagnosis and during the early course of the disease. In patients with CD, smoking, need for surgery and younger age at first diagnosis were risk factors for the development of an EIM.     

Host-microbiome interaction in Crohn&rsquo;s disease: A familiar or familial issue?

An impaired interaction between the gut and the intestinal microbiome is likely to be the key element in the pathogenesis of Crohn’s disease (CD). Family studies have provided invaluable information on CD pathogenesis and on its etiology. Relatives share the same genetic risk of developing the disease as affected subjects. Relatives also exhibit similar features relating to their host-microbiome interaction, namely genetic variants in loci involved in detecting bacteria, a greater sero-reactivity to microbial components, and an impaired intestinal permeability. The burden of environmental factors such as cigarette smoking and dysbiosis also seems to be particularly relevant in these genetically predisposed subjects. Diet is emerging as an important factor and could account for the changing epidemiology of CD in recent years. Despite the pivotal role of genetics in the disease’s pathogenesis (especially in familial CD), screening tests in healthy relatives cannot be recommended.     

Influence of environmental factors in the development of inflammatory bowel diseases

Idiopathic inflammatory bowel diseases(IBD), Crohn's disease(CD) and ulcerative colitis(UC), are multifactorial diseases that are manifested after disruption of a genetic predisposed individual and its intestinal microflora through an environmental stimulus. Urbanization and industrialization are associated with IBD. Epidemiological data, clinical observations and family/immigrants studies indicate the significance of environmental influence in the development of IBD. Some environmental factors have a different effect on the subtypes of IBD. Smoking and appendectomy is negatively associated with UC, but they are aggravating factors for CD. A westernized high fat diet, full of refined carbohydrates is strongly associated with the development of IBD, contrary to a high in fruit, vegetables and polyunsaturated fatty acid-3 diet that is protective against these diseases. High intake of nonsteroidal antiinflammatory drug and oral contraceptive pills as well as the inadequacy of vitamin D leads to an increased risk for IBD and a more malignant course of disease. Moreover, other factors such as air pollution, psychological factors, sleep disturbances and exercise influence the development and the course of IBD. Epigenetic mechanism like DNA methylation, histone modification and altered expression of miR NAS could explain the connection between genes and environmental factors in triggering the development of IBD.     

Clinical prognostic factors for disabling Crohn’s disease: A systematic review and meta-analysis

AIM: To identify demographic and clinical factors asso-ciated with disabling Crohn’s disease (CD). METHODS: A systematic review and meta-analysisof observational studies, focusing on the factors that can predict the prognosis of different outcomes of CD was undertaken. PubMed, ISI Web of Knowledge and Scopus were searched to identify studies investigat-ing the above mentioned factors in adult patients with CD. Studies were eligible for inclusion if they describe prognostic factors in CD, with inclusion and exclusion criteria defined as follows. Studies with adult patients and CD, written in English and studying association between clinical factors and at least one prognosis out-come were included. Meta-analysis of effects was un-dertaken for the disabling disease outcome, using odds ratio (OR) to assess the effect of the different factors in the outcome. The statistical method used was Mantel-Haenszel for fixed effects. The 16-item quality assess-ment tool (QATSDD) was used to assess the quality of the studies (range: 0-42). RESULTS: Of the 913 papers initially selected, sixty studies were reviewed and three were included in the systematic review and meta-analysis. The global QA-TSDD scores of papers were 18, 21 and 22. Of a total of 1961 patients enrolled, 1332 (78%) were classified with disabling disease five years after diagnosis. In two studies, age at diagnosis was a factor associated with disabling disease five years after diagnosis. Individu-als under 40 years old had a higher risk of developing disabling disease. In two studies, patients who were treated with corticosteroids on the first flare developed disabling disease five years after diagnosis. Further, perianal disease was found to be relevant in all of the studies at two and five years after diagnosis. Finally, one study showed localization as a factor associated with disabling disease five years after diagnosis, with L3 being a higher risk factor. This meta-analysis showed a significantly higher risk of developing disabling dis-ease at five year     

Crucial steps in the natural history of inflammatory bowel disease

Inflammatory bowel diseases (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), are chronic, progressive and disabling disorders. Over the last few decades, new therapeutic approaches have been introduced which have led not only to a reduction in the mortality rate but also offered the possibility of a favorable modification in the natural history of IBD. The identification of clinical, genetic and serological prognostic factors has permitted a better stratification of the disease, thus allowing the opportunity to indicate the most appropriate therapy. Early treatment with immunosuppressive drugs and biologics has offered the opportunity to change, at least in the short term, the course of the disease by reducing, in a subset of patients with IBD, hospitalization and the need for surgery. In this review, the crucial steps in the natural history of both UC and CD will be discussed, as well as the factors that may change their clinical course. The methodological requirements for high quality studies on the course and prognosis of IBD, the true impact of environmental and dietary factors on the clinical course of IBD, the clinical, serological and genetic predictors of the IBD course (in particular, which of these are relevant and appropriate for use in clinical practice), the impact of the various forms of medical treatment on the IBD complication rate, the role of surgery for IBD in the biologic era, the true magnitude of risk of colorectal cancer associated with IBD, as well as the mortality rate related to IBD will be stressed; all topics that are extensively discussed in separate reviews included in this issue of World Journal of Gastroenterology.     

Mycobacterium avium subspecies paratuberculosis causes Crohn's disease in some inflammatory bowel disease patients

Crohn’s disease (CD) is a chronic inflammatory condition that plagues millions all over the world. This debilitating bowel disease can start in early childhood and continue into late adulthood. Signs and symptoms are usually many and multiple tests are often required for the diagnosis and confirmation of this disease. However, little is still understood about the cause(s) of CD. As a result, several theories have been proposed over the years. One theory in particular is that Mycobacterium avium subspecies paratuberculosis (MAP) is intimately linked to the etiology of CD. This fastidious bacterium also known to cause Johne’s disease in cattle has infected the intestines of animals for years. It is believed that due to the thick, waxy cell wall of MAP it is able to survive the process of pasteurization as well as chemical processes seen in irrigation purification systems. Subsequently meat, dairy products and water serve as key vehicles in the transmission of MAP infection to humans (from farm to fork) who have a genetic predisposition, thus leading to the development of CD. The challenges faced in culturing this bacterium from CD are many. Examples include its extreme slow growth, lack of cell wall, low abundance, and its mycobactin dependency. In this review article, data from 60 studies showing the detection and isolation of MAP by PCR and culture techniques have been reviewed. Although this review may not be 100% comprehensive of all studies, clearly the majority of the studies overwhelmingly and definitively support the role of MAP in at least 30%-50% of CD patients. It is very possible that lack of detection of MAP from some CD patients may be due to the absence of MAP role in these patients. The latter statement is conditional on utilization of methodology appropriate for detection of human MAP strains. Ultimately, stratification of CD and inflammatory bowel disease patients for the presence or absence of MAP is necessary for appropriate and effective treatment which may lead to a cure.     

Inflammatory bowel disease course in Crohn’s disease: Is the natural history changing?

Crohn’s disease(CD)is a multifactorial potentially debilitating disease.It has a variable disease course,but the majority of patients eventually develop penetrating or stricturing complications leading to repeated surgeries and disability.Studies on the natural history of CD provide invaluable data on its course and clinical predictors,and may help to identify patient subsets based on clinical phenotype.Most data are available from referral centers,however these outcomes may be different from those in population-based cohorts.New data suggest the possibility of a change in the natural history in Crohn’s disease,with an increasing percentage of patients diagnosed with inflammatory disease behavior.Hospitalization rates remain high,while surgery rates seem to have decreased in the last decade.In addition,mortality rates still exceed that of the general population.The impact of changes in treatment strategy,including increased,earlier use of immunosuppressives,biological therapy,and patient monitoring on the natural history of the disease are still conflictive.In this review article,the authors summarize the available evidence on the natural history,current trends,and predictive factors for evaluating the disease course of CD.     

Pharmacological- and non-pharmacological therapeutic approaches in inflammatory bowel disease in adults

Inflammatory bowel diseases(IBDs) are a group of chronic inflammatory conditions mainly of the colon and small intestine. Crohn's disease(CD) and ulcerative colitis(UC) are the most frequent types of IBD. IBD is a complex disease which arises as a result of the interaction of environmental, genetic and immunological factors. It is increasingly thought that alterations of immunological reactions of the patients to their own enterable bacteria(microfilm) may contribute to inflammation. It is characterized by mucosal and sub mucosal inflammation, perpetuated by infiltration of activated leukocytes. CD may affect the whole gastrointestinal tract while UC only attacks the large intestine. The therapeutic goal is to achieve a steroidfree long lasting remission in both entities. UC has the possibility to be cured by a total colectomy, while CD never can be cured by any operation. A lifelong intake of drugs is mostly necessary and essential. Medical treatment of IBD has to be individualized to each patient and usually starts with anti-inflammatory drugs. The choice what kind of drugs and what route administered(oral, rectal, intravenous) depends on factors including the type, the localization, and severity of the patient's disease. IBD may require immune-suppression to control symptoms such as prednisolone, thiopurines, calcineurin or sometimes folic acid inhibitors or biologics like TNF-α inhibitors or anti-integrin antibodies. For both types of disease(CD, UC) the same drugs are available but they differ in their preference in efficacy between CD and UC as 5-aminosalicylic acid for UC or budesonide for ileocecal CD. As therapeutic alternative the main mediators of the disease, namely the activated pro-inflammatory cytokine producing leukocytes can be selectively removed via two apheresis systems(Adacolumn and Cellsorba) in steroid-refractory or dependent cases. Extracorporeal photopheresis results in an increase of regulatory B cells, regulatory CD8~+ T cells and T-regs Type 1. Both types of apheresis were able to induce clinical remission and mucosal healing accompanied by tapering of steroids.     

A meta-analysis of the placebo rates of remission and response in clinical trials of active Crohn's disease

BACKGROUND & AIMS: Placebo-controlled, randomized clinical trials (PC-RCTs) are commonly used to assess therapies for Crohn's disease (CD). Knowledge of the placebo rates of remission and response and understanding of design factors that influence these rates is important for designing future clinical trials evaluating pharmacotherapy of CD. The aims of this study were to estimate rates of remission and response in patients with active CD receiving placebo and to identify factors influencing these rates. METHODS: We performed a systematic review and meta-analysis of PC-RCTs evaluating therapies for active CD identified from MEDLINE from 1966 to 2001. RESULTS: The pooled estimates of the placebo rates of remission and response were 18% (95% confidence interval, 14%-24%; range, 0%-50%) and 19% (95% confidence interval, 13%-28%; range, 0%-46%), respectively, both with significant heterogeneity among studies (P < 0.01 for remission, P < 0.03 for response). In multivariate models, study duration, number of study visits, and entry Crohn's Disease Activity Index score were important predictors of the placebo remission rate, with study duration the most important. However, no single factor could account for all of the heterogeneity. Factors that influence the placebo response rates were similar to those affecting the placebo remission rates. The absolute benefit of active treatment beyond placebo was generally larger when outcome was measured by response than remission. CONCLUSIONS: Placebo remission and response rates in PC-RCTs for active CD are variable. Study duration, number of study visits, and disease severity at entry have a large influence on placebo remission rates.     

Capsule endoscopy in Crohn’s disease: Are we seeing any better?

Crohn’s disease (CD) is a complex, immune-mediated disorder that often requires a multi-modality approach for optimal diagnosis and management. While traditional methods include ileocolonoscopy and radiologic modalities, increasingly, capsule endoscopy (CE) has been incorporated into the algorithm for both the diagnosis and monitoring of CD. Multiple studies have examined the utility of this emerging technology in the management of CD, and have compared it to other available modalities. CE offers a noninvasive approach to evaluate areas of the small bowel that are difficult to reach with traditional endoscopy. Furthermore, CE maybe favored in specific sub segments of patients with inflammatory bowel disease (IBD), such as those with IBD unclassified (IBD-U), pediatric patients and patients with CD who have previously undergone surgery.     

Antidepressants can treat inflammatory bowel disease through regulation of the nuclear factor-κB/nitric oxide pathway and inhibition of cytokine production: A hypothesis

Inflammatory bowel disease (IBD) is a group of inflammatory disorders mainly affecting the colon and small intestine. The main types of IBD are Crohn’s disease (CD) and ulcerative colitis (UC). UC is restricted to the large intestine whereas CD can affect any part of the gastrointestinal tract. Treating this disorder depends on the form and level of severity. Common treatment involves an anti-inflammatory drug, such as mesalazine, and an immunosuppressant, such as prednisone. Several signaling pathways, including nuclear factor (NF)-κB and nitric oxide (NO), and genetic and environmental factors are believed to play an important role in IBD. Amitriptyline is a commonly used antidepressant with known anti-inflammatory activities. Amitriptyline also acts on the NF-κB/NO pathway or cytokine production. Therefore, we hypothesize that antidepressants like amitriptyline can be pioneered and considered effective as an innovative and effective therapeutic in the treatment and attenuation of development of IBD in adjusted doses.     

Crohn's disease presenting as acute gastrointestinal hemorrhage

Severe gastrointestinal (GI) hemorrhage is a rare complication of Crohn’s disease (CD). Although several surgical and non-surgical approaches have been described over the last 2 decades this complication still poses significant diagnostic and therapeutic challenges. Given the relative infrequency of severe bleeding in CD, available medical literature on this topic is mostly in the form of retrospective case series and reports. In this article we review the risk factors, diagnostic modalities and treatment options for the management of CD presenting as GI hemorrhage.     

Interleukin-21 enhances T-helper cell type I signaling and interferon-gamma production in Crohn's disease

BACKGROUND & AIMS: T-helper (Th)1 cells play a central role in the pathogenesis of tissue damage in Crohn's disease (CD). Interleukin (IL)-12/STAT4 signaling promotes Th1 cell commitment in CD, but other cytokines are needed to maintain activated Th1 cells in the mucosa. In this study, we examined the expression and role of IL-21, a T-cell-derived cytokine of the IL-2 family; in tissues and cells isolated from patients with inflammatory bowel disease. METHODS: IL-21 was examined by Western blotting in whole mucosa and lamina propria mononuclear cells (LPMCs) from patients with CD, ulcerative colitis (UC), and controls. We also examined the effects of exogenous IL-12 on IL-21 production, as well as the effects of blocking IL-21 with an IL-21-receptor Ig fusion protein. Interferon (IFN)-gamma was measured in the culture supernatants by enzyme-linked immunosorbent assay, and phosphorylated STAT4 and T-bet were examined by Western blotting. RESULTS: IL-21 was detected in all samples, but its expression was higher at the site of disease in CD in comparison with UC and controls. Enhanced IL-21 was seen in both ileal and colonic CD and in fibrostenosing and nonfibrostenosing disease. IL-12 enhanced IL-21 in normal lamina propria lymphocytes through an IFN-gamma-independent mechanism, and blocking IL-12 in CD LPMCs decreased anti-CD3-stimulated IL-21 expression. Neutralization of IL-21 in CD LPMC cultures decreased phosphorylated STAT4 and T-bet expression, thereby inhibiting IFN-gamma production. CONCLUSIONS: Our data suggest that IL-21 contributes to the ongoing Th1 mucosal response in CD.     

Inflammatory bowel disease in India - Past,present and future

There is rising incidence and prevalence of inflammatory bowel disease (IBD) in India topping the Southeast Asian (SEA) countries. The common genes implicated in disease pathogenesis in the West are not causal in Indian patients and the role of “hygiene hypothesis” is unclear. There appears to be a North-South divide with more ulcerative colitis (UC) in north and Crohn’s disease (CD) in south India. IBD in second generation Indian migrants to the West takes the early onset and more severe form of the West whereas it retains the nature of its country of origin in migrants to SEA countries. The clinical presentation is much like other SEA countries (similar age and sex profile, low positive family history and effect of smoking, roughly similar disease location, use of aminosalicylates for CD, low use of biologics and similar surgical rates) with some differences (higher incidence of inflammatory CD, lower perianal disease, higher use of aminosalicylates and azathioprine and lower current use of corticosteroids). UC presents more with extensive disease not paralleled in severity clinically or histologically, follows benign course with easy medical control and low incidence of fulminant disease, cancer, complications, and surgery. UC related colorectal cancer develop in an unpredictable manner with respect to disease duration and site questioning the validity of strict screening protocol. About a third of CD patients get antituberculosis drugs and a significant number presents with small intestinal bleed which is predominantly afflicted by aggressive inflammation. Biomarkers have inadequate diagnostic sensitivity and specificity for both. Pediatric IBD tends to be more severe than adult. Population based studies are needed to address the lacunae in epidemiology and definition of etiological factors. Newer biomarkers and advanced diagnostic techniques (in the field of gastrointestinal endoscopy, molecular pathology and genetics) needs to be developed for proper disease definition and treatment.     

Predictors of recurrence of Crohn’s disease after ileocolectomy: A review

Recurrence after ileocolectomy for Crohn’s disease (CD) is common and occurs in up to 80% of patients. Such recurrence can result in repeated surgical interventions, an increased need for medical treatment and, frequently, an impaired quality of life. The aim of this overview is to provide a summary of the factors associated with disease recurrence after ileocolectomy for CD. Recurrence can be measured clinically or endoscopically using established scoring systems. Radiology and serologic tests can also be used, oftentimes in conjunction with endoscopy and/or clinical findings. Many patient and operative factors as well as pharmacologic treatments have been studied as potential predictors of recurrence. Of these, only smoking and immunomodulatory or biologic medical treatment have repeatedly been shown to effect recurrence. Genetic predictors have been studied and suggested but further evaluation in larger cohorts is necessary. This paper highlights validated, reproducible scoring systems for recurrence and the key findings of studies including patient demographics, operative techniques, various pharmacological treatments and histological findings as predictors of recurrence post ileocolectomy in CD.     

Infectious etiopathogenesis of Crohn’s disease

Important advances during the last decade have been made in understanding the complex etiopathogenesis of Crohn’s disease(CD).While many gaps in our knowledge still exist,it has been suggested that the etiology of CD is multifactorial including genetic,environmental and infectious factors.The most widely accepted theory states that CD is caused by an aggressive immune response to infectious agents in genetically predisposed individuals.The rise of genome-wide association studies allowed the identification of loci and genetic variants in several components of host innate and adaptive immune responses to microorganisms in the gut,highlighting an implication of intestinal microbiota in CD etiology.Moreover,numerous independent studies reported a dysbiosis,i.e.,a modification of intestinal microbiota composition,with an imbalance between the abundance of beneficial and harmful bacteria.Although microorganisms including viruses,yeasts,fungi and bacteria have been postulated as potential CD pathogens,based on epidemiological,clinicopathological,genetic and experimental evidence,their precise role in this disease is not clearly defined.This review summarizes the current knowledge of the infectious agents associated with an increased risk of developing CD.Therapeutic approaches to modulate the intestinal dysbiosis and to target the putative CD-associated pathogens,as well as their potential mechanisms of action are also discussed.