Jacques Belaiche

Common variants in the NLRP3 region contribute to Crohn's disease susceptibility

We used a candidate gene approach to identify a set of SNPs, located in a predicted regulatory region on chromosome 1q44 downstream of NLRP3 (previously known as CIAS1 and NALP3) that are associated with Crohns disease. The associations were consistently replicated in four sample sets from individuals of European descent. In the combined analysis of all samples (710 father-mother-child trios, 239 cases and 107 controls), these SNPs were strongly associated with risk of Crohns disease (Pcombined = 3.49 × 10−9, odds ratio = 1.78, confidence interval = 1.47–2.16 for rs10733113), reaching a level consistent with the stringent significance thresholds imposed by whole-genome association studies. In addition, we observed significant associations between SNPs in the associated regions and NLRP3 expression and IL-1β production. Mutations in NLRP3 are known to be responsible for three rare autoinflammatory disorders. These results suggest that the NLRP3 region is also implicated in the susceptibility of more common inflammatory diseases such as Crohns disease.

Predictors of severe Crohn's disease

Objective. A model based on clinical characteristics at diagnosis and predicting the early development of disabling Crohns disease (CD) has recently been proposed in order to target patients for early intervention. The objectives of this study were to confirm the predictive factors established in a previous study and to establish the predictive factors for the development of severe disease characterized by the development of clinically significant non-reversible damage. Material and methods. Our retrospective study comprised a total of 361 patients with CD from our clinical database with a follow-up of longer than 5 years. Clinical, demographic and biological factors associated with the development of disabling disease (according to predefined criteria) within 5 years after the diagnosis of CD and with the time to development of severe disease (according to predefined criteria) were successively studied by univariate and multivariate analyses. Results. The rate of disabling CD within 5 years after diagnosis was 57.9%. Perianal lesions, the need for steroids to treat the first flare and ileo-colonic location, but not age below 40 years were confirmed as predictive markers. The rate of severe disease was 37.4%. Stricturing behaviour (HR: 2.11 (95% CI: 1.39–3.20)) and loss of weight (>5kg) (HR: 1.67 (95% CI: 1.14–2.45)) at diagnosis were independently associated with the time to development of severe disease. The predictive performances of the models generated were low. Conclusions. Disabling and severe CD developed in roughly one-third and two-thirds of our patients, respectively. Some clinical predictive markers could be found or even confirmed but their performances were low.

Proteomics for prediction and characterization of response to infliximab in Crohn's disease: A pilot study

OBJECTIVESnInfliximab is the first anti-TNFalpha accepted by the Food and Drug Administration for use in inflammatory bowel disease treatment. Few clinical, biological and genetic factors tend to predict response in Crohns disease (CD) patient subcategories, none widely predicting response to infliximab.nnnDESIGN AND METHODSnTwenty CD patients showing clinical response or non response to infliximab were used for serum proteomic profiling on Surface Enhanced Lazer Desorption Ionisation-Time of Flight-Mass Spectrometry (SELDI-TOF-MS), each before and after treatment. Univariate and multivariate data analysis were performed for prediction and characterization of response to infliximab.nnnRESULTSnWe obtained a model of classification predicting response to treatment and selected relevant potential biomarkers, among which platelet aggregation factor 4 (PF4). We quantified PF4, sCD40L and IL-6 by ELISA for correlation studies.nnnCONCLUSIONSnThis first proteomic pilot study on response to infliximab in CD suggests association between platelet metabolism and response to infliximab and requires validation studies on a larger cohort of patients.

Clinical and genetic factors associated with sacroiliitis in Crohn's disease

Background and Aim:u2002 Radiographic sacroiliitis (SI), often asymptomatic, is considered the most frequent extra‐intestinal manifestation (EIM) of Crohns disease (CD). Data on the association of SI with other clinical features of CD are limited. Association of SI with CARD15 polymorphisms has recently been suggested. In a multicenter study, we investigated the association of SI in CD patients with clinical phenotypes, other EIM and CARD15 polymorphisms.

Genetic variation in the familial Mediterranean fever gene (MEFV) and risk for Crohn's disease and ulcerative colitis

Background and Aims The familial Mediterranean fever (FMF) gene (MEFV) encodes pyrin, a major regulator of the inflammasome platform controlling caspase-1 activation and IL-1β processing. Pyrin has been shown to interact with the gene product of NLRP3, NALP3/cryopyrin, also an important active member of the inflammasome. The NLRP3 region was recently reported to be associated with Crohns disease (CD) susceptibility. We therefore sought to evaluate MEFV as an inflammatory bowel disease (IBD) susceptibility gene. Methodology and Results MEFV colonic mucosal gene expression was significantly increased in experimental colitis mice models (TNBS p<0.0003; DSS p<0.006), in biopsies from CD (p<0.02) and severe ulcerative colitis (UC) patients (p<0.008). Comprehensive genetic screening of the MEFV region in the Belgian exploratory sample set (440 CD trios, 137 UC trios, 239 CD cases, 96 UC cases, and 107 healthy controls) identified SNPs located in the MEFV 5′ haplotype block that were significantly associated with UC (rs224217; pu200a=u200a0.003; A allele frequency: 56% cases, 45% controls), while no CD associations were observed. Sequencing and subsequent genotyping of variants located in this associated haplotype block identified three synonymous variants (D102D/rs224225, G138G/rs224224, A165A/rs224223) and one non-synonymous variant (R202Q/rs224222) located in MEFV exon 2 that were significantly associated with UC (rs224222: pu200a=u200a0.0005; A allele frequency: 32% in cases, 23% in controls). No consistent associations were observed in additional Canadian (256 CD trios, 91 UC trios) and Scottish (495 UC, 370 controls) sample sets. We note that rs224222 showed marginal association (pu200a=u200a0.012; G allele frequency: 82% in cases, 70% in controls) in the Canadian sample, but with a different risk allele. None of the NLRP3 common variants were associated with UC in the Belgian-Canadian UC samples and no significant interactions were observed between NLRP3 and MEFV that could explain the observed flip-flop of the rs224222 risk allele. Conclusion The differences in association levels observed between the sample sets may be a consequence of distinct founder effects or of the relative small sample size of the cohorts evaluated in this study. However, the results suggest that common variants in the MEFV region do not contribute to CD and UC susceptibility.

Genetics of ulcerative colitis: the come-back of interleukin 10

Crohn’s disease and ulcerative colitis are chronic, immune-mediated inflammatory diseases of the gastrointestinal tract, affecting up to 0.4% of the population in Western countries.1 They are considered complex multifactorial polygenic diseases. While dramatic progress has been made in deciphering the genetic architecture of Crohn’s disease, ulcerative colitis was somewhat left behind, with virtually no relevant studies published until very recently. Although both disorders are considered to belong to the same spectrum of pathologies, the first gene clearly associated with Crohn’s disease ( CARD-15 )2 3 did not seem to predispose to ulcerative colitis in any cohort in which it was tested. This finding highlighted some pathogenic differences between the two diseases, and reminded geneticists working on inflammatory bowel diseases (IBDs) of the more modest contribution of genetics to the predisposition to ulcerative colitis, reflected in a lower ratio of disease concordance between monozygotic and dizygotic twins.4 The lower heritability of ulcerative colitis also accounts for the fact that most of the linkage studies performed in the 1990s did not include sufficient ulcerative colitis-affected sib pairs to disclose ulcerative colitis-related loci. With few exceptions,5 6 7 reports of associations with candidate genes have not been confirmed. Recently, major advances in cataloguing common genetic variants in humans combined with the development of high-throughput single nucleotide polymorphism (SNP) genotyping capacity, have made large-scale, genome-wide association studies (GWASs) with hundreds of thousands of common SNPs feasible. These have dramatically increased the list of loci shown to be associated with Crohn’s disease,8 9 10 11 12 13 and now also with ulcerative colitis14 15 16 17 (table 1).nnView this table:nnTable 1 nSingle nucleotide polymorphisms (SNPs) significantly associated with ulcerative colitis, identified through genome-wide association studies15 16 17 or systematic testing after significant association with Crohn’s disease in genome-wide association studies14 …

Anti-TNF and Crohn's disease: when should we stop?

When to stop anti-TNF therapy in Crohns disease (CD)? This is a very important question both for patients and physicians. There is no published evidence to clearly and definitely answer this question. However data on natural history of CD, long term safety of biologics, outcome after immunosuppressors (IS) cessation and some preliminary studies on biologics cessation may help us to discuss this topic. One could argue that there is currently no good reason to stop anti-TNF therapy in a patient who is in stable remission and tolerate this drug very well. The decision to stop an anti-TNF treatment is thus currently based on a compromise between the benefits/risks and cost of such long term treatment. While it appears now clearly that prolonged anti-TNF therapy is associated with favourable outcome with sustained remission, reduced surgeries and hospitalisation as well as absence of significant increase in mortality or cancers, the cost-effectiveness which is probably favourable for short and mid-term treatment (up to one year), may be less optimal for very long term treatment. In this perspective however, prospective studies should be performed to adequately assess long term evolution, disease outcome, safety and global cost of strategies based on treatment reduction with IS maintenance alone or even full treatment cessation.

Anti-tumor Necrosis Factor Nonresponders in Crohn's Disease : Therapeutic Strategies

Anti-TNF antibodies have revolutionized the treatment of Crohn’s disease. In pivotal trials, however, the frequencies of primary and secondary nonresponders appeared rather high with, by the end of 1 year of scheduled treatment, only one fifth of the patients initially treated still in sustained remission. Other studies and monocentric experiences have indicated that these seemingly disappointing results were partly due to suboptimal selection of the patients and absence of treatment optimization. Optimal selection of the patient includes proving active intestinal lesions and systemic inflammation as well as excluding stricturing or infectious complications. Treatment optimization includes potential immunosuppressive co-treatment and dose or administration interval adjustment of the anti-TNF. When a failure is confirmed with an anti-TNF despite such optimization, second- or third-line anti-TNFs have proved useful. Beyond that, a transient steroid course and surgical procedures still represent rescue option, waiting for new promising biologics in development.

Does the phenotype at diagnosis (e.g., fibrostenosing, inflammatory, perforating) predict the course of Crohn's disease?

Phenotypes of CD CD is characterized by a chronic inflammatory reaction of the bowel wall. This abnormal inflammation is usually transmural and involves immunoinflammatory cells as well as nonimmune cells, such as fibroblasts and endothelial cells. Some of these cells exhibit resistance to apoptosis, maintaining the inflammatory reaction, and they produce a broad range of cytokines. These cytokines induce the production of proteases, metalloproteinases, and growth factors involved in tissue remodeling. In some cases this remodeling will end up with an intestinal stricture, characterized by mucosal and submucosal fibrosis, with abnormal collagen deposition, as well as muscular hyperplasia. In other cases penetrating lesions may develop, in which deep fissures give rise to covert perforation, paraintestinal abscess, and free perforation or fistula. A fibrostenosing phenotype is characterized by the presence of clinically significant strictures giving rise to occlusive or subocclusive symptoms. A perforating phenotype is characterized by penetrating lesions. These can originate from the intestine and give rise not only to enteroenteric, entero-cutaneous, or entero-hollow organ fistula, but also to paraintestinal abscesses, infiltrations, or, seldom, peritonitis. These abdominal fistulizing lesions originate most of the time just upstream or at the beginning of a stricture and may thus be considered as a further complication of these stricturing lesions.1,2 This suggests that an increase in luminal pressure and parietal tension is a major factor favoring these lesions. They also can originate from the anal canal, the anorectal junction, or lower rectum and give rise to all the simple or complex lesions characterizing perianal CD. In this case the anal sphincter probably plays a role equivalent to a stricture, as a factor favoring perforating lesions. Although initially classified in the same phenotype of perforating CD,3 penetrating intraabdominal disease rather rarely coexists with perianal disease.4 This is probably due to the fact that these subphenotypes are related to different locations of the disease. Therefore, in the last proposed classification for CD these two subphenotypes were separated.5 An inflammatory phenotype is characterized by the absence of such perforating or fibrostenosing complication. The phenotype of CD is not an independent and isolated parameter. Besides the possible influence of endogenous (genetic influence on the inflammatory reaction and tissue remodeling) and exogenous (suggested influence of smoking) factors, the phenotype at diagnosis will depend on several more trivial parameters, such as the delay between symptoms and diagnosis or the location of the disease: strictures, for example, developing more often in the small intestine than in the colon.

Does the behavior of Crohn's disease change over time?

The behavior of Crohn’s disease (CD) is usually defined by the development of fistulizing or stricturing lesions.1 Early lesions of CD are thought to be superficial aphtoid lesions. If the intensity of the inflammation increases, the lesions may become deeper and transmural. The reason why in some patients this transmural inflammatory process will involve muscular propria layer with fibrosis and smooth muscle cells hyperplasia giving rise to stricture or dissect this layer to give rise to penetrating lesions is unknown. It could be “by chance,” driven by circumstantial external factors. However, 2 facts are against this unique hypothesis and suggest an innate inclination potentially genetically determined: 1) there is a significant concordance among multiply affected families2 and among monozygotic twins3 for the development of such lesions; and 2) a given patient tends to develop the same type of lesion after surgical resection of intestinal segments.4 If we consider these facts we could conclude that there is a fixed disease behavior in a given patient and that it does not change over time. However, it is not that simple, since these lesions will develop with time.5,6 If we try to classify a patient at a given timepoint over the course of the disease he or she may fall into anyone of 3 categories: “nonstricturing nonpenetrating, stricturing, or penetrating,” even if he or she has a fixed inclination to develop another type of lesion. If we have to classify the same patient a few years later, he or she may fall into another category. Practically, at diagnosis more than 70% of the patients present with a pure inflammatory behavior, while a bit more than 10% have a stricturing behavior and a similar proportion penetrating behavior.5 Ten years later about onethird of the patients have developed penetrating lesions and another third pure stricturing lesions. Thereafter, the proportion of patients with pure stricturing lesions tends to remain stable, while penetrating lesions progressively increase to reach up to 50% after 20 years.5 These considerations may have an impact both on clinical and pathophysiological aspects. From a clinical point of view it is very important to know what type of lesions are present at a given timepoint to help to decide the therapeutic strategy. Indeed, inflammatory, stricturing, or penetrating lesions do not respond to treatment the same way. The drugs we have currently to treat CD are essentially active on the inflammatory lesions. The effect infliximab and to a lesser extent immunosuppressants have on fistulizing disease is probably related to their powerful control of inflammatory process, which may secondarily allow scarring of fistulous tracks, the healing of these tracks being much slower than the control of inflammation and the scarring of mucosal lesions. As far as stricturing lesions, no treatment has proven effective so far. On the other hand, when discussing long-term therapeutic strategy it may be important to know the inclination for developing stricturing or penetrating lesions because this may lead to more aggressive maintenance treatment to avoid such complications, although no controlled data have really proven the efficacy of such preventive treatment. This inclination may be a stable trait and may be inferred from the past history and to some extent the family history of the patient.2–4 From a pathophysiological point of view, understanding the mechanisms that underlie the development of stricturing and penetrating complications is important because it may help to subclassify CD, which would probably help in understanding the basis of the disease. The difficulty here is that, as with the disease itself, the behavior of CD is most probably of a multifactorial polygenic character. The factor for which an influence on disease behavior is the clearest is probably disease location.7,8 Ileal CD has been associated with the development of both stricturing and intraabdominal penetrating lesions. The caliber of the ileum, which is smaller than the colon, and the role of the ileocecal valve are suspected in this phenomenon. Immunology and microflora of the ileum are also different from that of the colon. The anal canal is also a common place for CD stricture, and fistulae often arise just upward from the low rectum or the proximal anal canal. Globally it is rather rare to find a fistula in CD that is not associated with a downward stricture.9 The mechanism could be an increase in luminal pressure favoring penetrating lesions developing from transmural inflammation. Although some genes have been suggested to be associated with CD behavior in isolated studies, none has really been confirmed on a large scale and with convincing methods of analysis. Smoking has been associated in some studies with the development of penetrating lesions.8,10 Treatment could also have an influence. However, there are no prospective controlled data to substantiate this. From the Department of Gastroenterology CHU of Liege, Liege, GIGA research University of Liege, Liege, Belgium. Copyright