Gerd Bouma

The immunological and genetic basis of inflammatory bowel disease

The inflammatory bowel diseases (IBDs), Crohns disease and ulcerative colitis, are chronic inflammatory disorders of the gastrointestinal tract. Enormous progress has been made recently in understanding the pathogenesis of these diseases. Through the study of patients and mouse models, it has emerged that Crohns disease is driven by the production of interleukin-12 (IL-12) and interferon-γ (IFN-γ), whereas ulcerative colitis is probably driven by the production of IL-13. A second area of progress is in the identification of specific genetic abnormalities that are responsible for disease. The most important finding is the identification of mutations in the gene that encodes NOD2 (nucleotide-binding oligomerization domain 2) protein in a subgroup of patients with Crohns disease. Here, we discuss these recent findings and the implications for therapy.

A TaqI polymorphism in the 3′UTR of the IL-12 p40 gene correlates with increased IL-12 secretion

Interleukin-12 (IL-12) is a key cytokine for the induction of Th1 immune responses. We evaluated whether a TaqI polymorphism in the 3′UTR of the IL-12 p40 gene affects secretion of IL-12 in vitro, and whether this polymorphism is associated with susceptibility to Crohns disease (CD). IL-12 p40 and p70 secretion by monocytes in relation to genotype was determined in 63 healthy donors. Genotype and allele frequencies of the TaqI polymorphism in 150 CD patients were compared with 145 ethnically matched healthy controls (HC). No significant association was found between genotype and IL-12 p40 secretion after stimulation of monocytes with SAC+IFNγ. In contrast, increasing IL-12 p70 secretion was found across the categories of non-carriers, heterozygotes and homozygotes for the variant allele (median values±SEM: 147±27, 282±51 and 482±34 pg/ml, respectively; P<0.005). The allele and genotype frequencies of this polymorphism in patients with CD did not differ statistically significantly from HC. The presence of a TaqI polymorphism in the IL12 p40 3′UTR correlates with increased in vitro IL-12 p70, but not p40 secretion. While this polymorphism does not appear to be correlated with susceptibility to CD in the limited population of patients tested here, it could influence the occurrence of the disease in certain subsets of patients.

Double-balloon endoscopy as the primary method for small-bowel video capsule endoscope retrieval

BACKGROUND Capsule retention in the small bowel is a known complication of small-bowel video capsule endoscopy. Surgery is the most frequently used method of capsule retrieval. OBJECTIVE To determine the incidence and causes of capsule retention and to describe double-balloon endoscopy (DBE) as the primary technique used for capsule retrieval. DESIGN Retrospective analysis of all video capsule studies was performed at our center, and evaluation of the outcome of DBE was the first method used to retrieve entrapped video capsules. SETTING Tertiary referral center. PATIENTS A total of 904 patients who underwent small-bowel video capsule endoscopy. INTERVENTIONS Capsule retrieval by DBE. MAIN OUTCOME MEASUREMENTS The number of patients in whom capsule retention occurred and the number of patients in whom an entrapped capsule could be retrieved by using DBE. RESULTS Capsule retention occurred in 8 patients (incidence 0.88%; 95% CI, 0.41%-1.80%) and caused acute small-bowel obstruction in 6 patients. All retained capsules were successfully removed during DBE. Five patients underwent elective surgery to treat the underlying cause of capsule retention. One patient required emergency surgery because of multiple small-bowel perforations. LIMITATIONS Retrospective design. CONCLUSIONS In our series, the incidence of capsule retention was low. DBE is a reliable method for removing retained capsules and might prevent unnecessary surgery. If surgery is required, preoperative capsule retrieval allows preoperative diagnosis, adequate staging in case of malignancy, and optimal surgical planning.

Mycophenolate mofetil: role in autoimmune hepatitis and overlap syndromes.

Aliment Pharmacol Ther 2011; 34: 335–343

Update on the Diagnosis and Management of Refractory Coeliac Disease

A small subset of coeliac disease (CD) patients experiences persisting or recurring symptoms despite strict adherence to a gluten-free diet (GFD). When other causes of villous atrophy have been excluded, these patients are referred to as refractory celiac disease (RCD) patients. RCD can be divided in two types based on the absence (type I) or presence (type II) of an, usually clonal, intraepithelial lymphocyte population with aberrant phenotype. RCDI usually runs a benign course and may be difficult to be differentiated from uncomplicated, slow responding CD. In contrast, RCDII can be defined as low-grade intraepithelial lymphoma and frequently transforms into an aggressive enteropathy associated T-cell lymphoma with dismal prognosis. This paper describes the clinical characteristics of RCDI and RCDII, diagnostic approach, and the latest insights in treatment options.

Prevalence and Characterization of Self-Reported Gluten Sensitivity in The Netherlands

Background: A growing number of individuals reports symptoms related to the ingestion of gluten-containing food in the absence of celiac disease. Yet the actual prevalence is not well established. Methods: Between April 2015 and March 2016, unselected adults visiting marketplaces, dental practices and a university in The Netherlands were asked to complete a modified validated questionnaire for self-reported gluten sensitivity (srGS). Results: Among the 785 adults enquired, two had celiac disease. Forty-nine (6.2%) reported symptoms related to the ingestion of gluten-containing food. These individuals were younger, predominantly female and lived more frequently in urban regions compared with the other respondents. Symptoms reported included bloating (74%), abdominal discomfort (49%) and flatulence (47%). A total of 23 (47%) srGS individuals reported having had tried a gluten-free or gluten-restricted diet. Abdominal discomfort related to fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP)-containing food was more often reported in srGS individuals compared with the other respondents (73.5% vs. 21.7%, p < 0.001). Conclusion: Self-reported GS is common in The Netherlands, especially in younger individuals, females and urban regions, although the prevalence was lower than in a comparable recent UK study. It cannot be excluded that FODMAPs are in part responsible for these symptoms.

Mechanisms and management of refractory coeliac disease

A small subset of patients with coeliac disease become refractory to a gluten-free diet with persistent malabsorption and intestinal villous atrophy. The most common cause of this condition is inadvertent gluten exposure, but concomitant diseases leading to villous atrophy should also be considered and excluded. After exclusion of these conditions, patients are referred to as having refractory coeliac disease, of which two categories are recognized based on the absence (type I) or presence (type II) of a clonal expansion of premalignant intraepithelial lymphocyte population with a high potential for transformation into an overt enteropathy-associated T-cell lymphoma. Type I disease usually has a benign course that can be controlled by mild immunosuppressive treatment, but type II can be more severe with cladribine with or without autologous stem cell transplantation effective as treatment. Patients who fail to respond to cladribine therapy, however, still have a high risk of malignant transformation. Insights into the immunophenotype of these cells and the recognition that type II disease is a low-grade, no-mass lymphoma opens avenues for new treatment strategies, including chemotherapeutic and immunomodulating strategies. This Review will provide an overview of refractory coeliac disease, discussing mechanisms, diagnosis and management.

A polymorphism in the coding region of Il12b promotes IL-12p70 and IL-23 heterodimer formation.

IL-12 and IL-23 are heterodimeric cytokines involved in the induction of Th1 and Th17 immune responses. Previous work indicated that a region on chromosome 11 encoding the IL-12p40 subunit regulates strain differences in susceptibility to murine trinitrobenzene sulfonic acid-induced colitis. In addition, this region determines strain differences in LPS-induced IL-12 responses. In this study, we investigated how polymorphisms in the coding region of murine Il12b influence IL-12 and IL-23 heterodimer formation. Transfection studies using constructs containing IL-12p35 linked to IL-12p40 from the colitis-resistant C57BL/6 strain or to the polymorphic p40 variant from the colitis-susceptible SJL/J strain demonstrated that SJL/J-derived p40 constructs synthesized significantly more IL-12p70 than did constructs harboring the C57BL/6-p40 variant. This could not be attributed to differences in synthesis rate or secretion, implicating a greater affinity of SJL/J-derived IL-12p40 for its IL-12p35 subunit. This greater affinity is also associated with increased IL-23 synthesis. In addition, C57BL/6 mice transgenic for the SJL/J 40 variant synthesized significantly more IL-12p70 upon LPS challenge and were more prone to develop colonic inflammation than did C57BL/6 mice transgenic for the C57BL/6-p40 variant. The more efficient binding of the polymorphic Il12b variant to p35 and p19 is most likely due to conformational changes following differential glycosylation as a consequence of the polymorphism. The high synthesis rate of the mature cytokines resulting from this efficient binding can lead to rapid proinflammatory skewing of immune responses and distortion of the homeostatic balance underlying the greater susceptibility for colitis.

Enteropathy-Associated T-Cell Lymphoma: Improving Treatment Strategies

Enteropathy-associated T-cell lymphoma (EATL) is a rare and usually rapidly fatal intestinal T-cell non-Hodgkin lymphoma. It arises from intraepithelial lymphocytes and has a high association with coeliac disease. The high mortality of EATL is associated not only with the very aggressive and often chemotherapy-refractory nature of the lymphoma. The poor condition of patients due to prolonged and severe malnutrition compromises the ability to deliver chemotherapy. There are no standardized treatment protocols, and the optimal therapy for EATL remains unclear. The primary step of treatment consists of local debulking, preferably as early as possible after EATL diagnosis. Morbidity and mortality seem to rise with advanced stages of disease due to tumour size progression, worse nutritional status and a higher risk of emergency surgery due to perforation. Standard induction therapy for EATL is anthracycline-based chemotherapy, preferably resumed between 2 and 5 weeks after surgery (depending on clinical condition). Intensification of therapy using high-dose chemotherapy followed by consolidation with BEAM and autologous stem cell transplantation is associated with better outcome. Notably, this treatment strategy has only been applied in patients eligible for this aggressive regimen which might reflect selection bias. Unfortunately, prognosis of EATL remains poor; 5-year survival varies from 8 to 60% depending on the eligibility to receive additional steps of therapy. New treatment strategies are urgently needed for a better prognosis of this lethal complication of coeliac disease. Brentuximab vedotin (anti-CD30) might be promising when added to conventional chemotherapy and is suggested as upfront treatment in EATL.

Hematopoietic stem cell transplantation for non-malignant gastrointestinal diseases

Both, autologous and allogeneic hematopoietic stem cell transplantation (HSCT) can be used to cure or ameliorate a variety of malignant and non-malignant diseases. The rationale behind this strategy is based on the concept of immunoablation using high-dose chemotherapy, with subsequent regeneration of naive T-lymphocytes derived from reinfused hematopoietic progenitor cells. In addition, the use of HSCT allows for the administration of high-dose chemotherapy (whether or not combined with immunomodulating agents such as antithymocyte globulin) resulting in a prompt remission in therapy-refractory patients. This review gives an update of the major areas of successful uses of HSCT in non-malignant gastrointestinal disorders. A Medline search has been conducted and all relevant published data were analyzed. HSCT has been proved successful in treating refractory Crohns disease (CD). Patients with refractory celiac disease type II and a high risk of developing enteropathy associated T-cell lymphoma have shown promising improvement. Data concerning HSCT and mesenchymal SCT in end-stage chronic liver diseases are encouraging. In refractory autoimmune gastrointestinal diseases high-dose chemotherapy followed by HSCT seems feasible and safe and might result in long-term improvement of disease activity. Mesenchymal SCT for a selected group of CD is promising and may represent a significant therapeutic alternative in treating fistulas in CD.