Age-of-onset-dependent influence of NOD2 gene variants on disease behaviour and treatment in Crohn's disease

NOD2 and Crohn's Disease Clinical Practice: From Epidemiology to Diagnosis and Therapy, Rewired

Crohn's disease (CD) is a chronic inflammatory bowel disease with a multifactorial pathogenesis involving environmental and genetic factors. Since the late 20th century, the discovery of the first susceptibility gene (NOD2, previously referred to as CARD15) for CD has paved the way for further investigations into the correlations between clinical features and genetics, and its potential impact on clinical practice has fueled the research in the last 2 decades. Recent therapeutic advancements involving novel biologic drugs and small molecules have shifted inflammatory bowel disease management from a disease-centered to a patient-centric approach. To date, the role of NOD2 has not been fully understood yet. Recent data suggest that its clinical impact may be greater than currently recognized. This review overviews the most common NOD2 variants' role in real-life clinical practice. These genetic variants increase the risk of developing the disease and can aid in tailoring diagnosis and treatment. They are associated with the stricturing phenotype and ileal involvement and increase the risk of steroid refractoriness. In the meantime, limited and inconclusive evidence exists regarding their predictive role in response to azathioprine, biologic drugs, and small molecules. Eventually, their role in increasing the risk for surgery is evident, especially in those with the L1007fs variant. If further trials will support the initial evidence reported so far, NOD2 genetic variants will emerge as possible candidates for developing precision medicine in CD.

NOD2 Polymorphisms May Direct a Crohn Disease Phenotype in Patients With Very Early-Onset Inflammatory Bowel Disease

NOD2/CARD15 was the first susceptibility gene recognized for adult-onset Crohn's (or Crohn) disease (CD). Recessive inheritance of NOD2 polymorphisms has been implicated as a mechanistic driver of pediatric-onset CD. In patients with very early-onset inflammatory bowel disease (VEO-IBD), however, the clinical relevance of NOD2 polymorphisms has not been fully established. Ten VEO-IBD patients with NOD2 polymorphisms ( NOD2 +) were compared to 16 VEO-IBD patients without genetic variants in NOD2 or any other VEO-IBD susceptibility genes ( NOD2 -). The majority of NOD2 + patients exhibited a CD-like phenotype (90%), linear growth impairment (90%), and arthropathy (60%), all of which were significantly more common than in the NOD2 - group ( P = 0.037, P = 0.004, P = 0.026, respectively). We propose that the presence of NOD2 polymorphisms in patients with VEO-IBD might confer a CD-like phenotype, linear growth impairment, and arthropathy. These findings should be validated in larger cohorts and may guide precision medicine for patients with VEO-IBD in the future.

Isolated Crohn's Colitis: Is Localization Crucial? Characteristics of Pediatric Patients From the CEDATA-GPGE Registry

INTRODUCTION

Pediatric patients with inflammatory bowel disease (IBD) are classified into Crohn's disease (CD), ulcerative colitis (UC), and unclassifiable (IBD-U). However, data provide evidence that ileal CD (L1) is distinct from colonic CD (L2). The aim of this study was to investigate the clinical features of isolated Crohn's colitis in a pediatric population.

MATERIAL AND METHODS

Children who were prospectively included in the CEDATA-GPGE registry on diagnosis were compared according to the diagnosis of CD with L2 vs. L1 and ileocolonic (L3) involvement pattern as well as IBD-U and UC. The clinical significance of L2 was investigated with regard to extraintestinal manifestations, treatment, surgery, and disease activity.

RESULTS

Fifty-two patients with L2 CD at a median age of 13.4 years (±3.8 SD) were compared with 182 L1 (13.8 ± 2.9 SD), 782 with L3 (12.8 ± 3.3 SD), 653 with UC (12.7 ± 3.8 SD), and 111 patients with IBD-U (11.9 ± 4.7 SD). Bloody stools at diagnosis were more common in L2 (44%) than in L1 (19.7%) and L3 (28.8%), but not as common as in UC (66.5%) and IBD-U (61.3%). Fewer CD patients with L2 (10.2%) received exclusive enteral nutrition therapy (EEN) as induction than patients with L1 (34.3%) and L3 (33.3%). After induction therapy, 42.3% of patients with L2 received immunosuppressants and 21% biologicals during follow-up (L1 56.5/10.5%; L3 59/21%; CU 43.5/11.9%; IBD-U 26.1/12.6%). Extraintestinal manifestations were more frequent in L2 (23.1%) vs. L1 (18.7%), L3 (20.2%), CU (15.8%), and IBD-U (11.7%). The number of patients requiring surgery did not differ within the CD subgroups and was significantly lower in UC and IBD-U. Perianal fistula surgery was significantly more common in L2 (44%) than in L1 (4.8%) or L3 (21.7%). In addition, the frequency of surgery for perianal abscesses was also more frequent in L2 (55.6%) than in L1 (12.7%) or L3 (38.4%).

CONCLUSIONS

The consideration of pediatric Crohn's colitis as a distinct disease seems necessary as it is characterized by extraintestinal manifestations (EIMs) with mainly joint involvement and perianal fistulas or abscesses requiring surgery and biologic therapy. Thus, colonic Crohn's disease may have an influence on the therapeutic stratification and should be addressed in further studies.

Prognostic biomarkers to identify patients likely to develop severe Crohn's disease: a systematic review

BACKGROUND

Identification of biomarkers that predict severe Crohn's disease is an urgent unmet research need, but existing research is piecemeal and haphazard.

OBJECTIVE

To identify biomarkers that are potentially able to predict the development of subsequent severe Crohn's disease.

DESIGN

This was a prognostic systematic review with meta-analysis reserved for those potential predictors with sufficient existing research (defined as five or more primary studies).

DATA SOURCES

PubMed and EMBASE searched from inception to 1 January 2016, updated to 1 January 2018.

REVIEW METHODS

Eligible studies were studies that compared biomarkers in patients who did or did not subsequently develop severe Crohn's disease. We excluded biomarkers that had insufficient research evidence. A clinician and two statisticians independently extracted data relating to predictors, severe disease definitions, event numbers and outcomes, including odds/hazard ratios. We assessed risk of bias. We searched for associations with subsequent severe disease rather than precise estimates of strength. A random-effects meta-analysis was performed separately for odds ratios.

RESULTS

In total, 29,950 abstracts yielded just 71 individual studies, reporting 56 non-overlapping cohorts. Five clinical biomarkers (Montreal behaviour, age, disease duration, disease location and smoking), two serological biomarkers (anti-Saccharomyces cerevisiae antibodies and anti-flagellin antibodies) and one genetic biomarker (nucleotide-binding oligomerisation domain-containing protein 2) displayed statistically significant prognostic potential. Overall, the strongest association with subsequent severe disease was identified for Montreal B2 and B3 categories (odds ratio 4.09 and 6.25, respectively).

LIMITATIONS

Definitions of severe disease varied widely, and some studies confounded diagnosis and prognosis. Risk of bias was rated as 'high' in 92% of studies overall. Some biomarkers that are used regularly in daily practice, for example C-reactive protein, were studied too infrequently for meta-analysis.

CONCLUSIONS

Research for individual biomarkers to predict severe Crohn's disease is scant, heterogeneous and at a high risk of bias. Despite a large amount of potential research, we encountered relatively few biomarkers with data sufficient for meta-analysis, identifying only eight biomarkers with potential predictive capability.

FUTURE WORK

We will use existing data sets to develop and then validate a predictive model based on the potential predictors identified by this systematic review. Contingent on the outcome of that research, a prospective external validation may prove clinically desirable.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016029363.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 45. See the NIHR Journals Library website for further project information.

Predicting Outcomes in Pediatric Crohn's Disease for Management Optimization: Systematic Review and Consensus Statements From the Pediatric Inflammatory Bowel Disease-Ahead Program

BACKGROUND & AIMS

A better understanding of prognostic factors within the heterogeneous spectrum of pediatric Crohn's disease (CD) should improve patient management and reduce complications. We aimed to identify evidence-based predictors of outcomes with the goal of optimizing individual patient management.

METHODS

A survey of 202 experts in pediatric CD identified and prioritized adverse outcomes to be avoided. A systematic review of the literature with meta-analysis, when possible, was performed to identify clinical studies that investigated predictors of these outcomes. Multiple national and international face-to-face meetings were held to draft consensus statements based on the published evidence.

RESULTS

Consensus was reached on 27 statements regarding prognostic factors for surgery, complications, chronically active pediatric CD, and hospitalization. Prognostic factors for surgery included CD diagnosis during adolescence, growth impairment, NOD2/CARD15 polymorphisms, disease behavior, and positive anti-Saccharomyces cerevisiae antibody status. Isolated colonic disease was associated with fewer surgeries. Older age at presentation, small bowel disease, serology (anti-Saccharomyces cerevisiae antibody, antiflagellin, and OmpC), NOD2/CARD15 polymorphisms, perianal disease, and ethnicity were risk factors for penetrating (B3) and/or stenotic disease (B2). Male sex, young age at onset, small bowel disease, more active disease, and diagnostic delay may be associated with growth impairment. Malnutrition and higher disease activity were associated with reduced bone density.

CONCLUSIONS

These evidence-based consensus statements offer insight into predictors of poor outcomes in pediatric CD and are valuable when developing treatment algorithms and planning future studies. Targeted longitudinal studies are needed to further characterize prognostic factors in pediatric CD and to evaluate the impact of treatment algorithms tailored to individual patient risk.

Impact of NOD2/CARD15 polymorphisms on response to monoclonal antibody therapy in Crohn's disease: a systematic review and meta-analysis

OBJECTIVE

Crohn's disease (CD) is frequently treated with anti-tumor necrosis factor (TNF)α monoclonal antibodies, and NOD2/CARD15 polymorphisms have been reported to predict treatment response. The purpose of this study was to perform a meta-analysis to determine the effect of NOD2/CARD15 polymorphisms on treatment response in patients with CD.

METHODS

Medline, Cochrane, EMBASE, and Google Scholar databases were searched until 19 December 2015 using the keywords: NOD2, CARD15, polymorphism, Crohn's disease. Randomized controlled trials, prospective, retrospective, and cohort studies of patients with CD who received NOD2/CARD15 genetic analysis and were treated with monoclonal antibodies were included. The primary outcome was treatment response.

RESULTS

Of 104 records identified, only four studies were relevant and included in the analysis. The four studies included 355 patients with CD, patient age ranged from 35 to 41 years, and the proportion of males ranged from 33% to 38%; however, only two studies reported age and sex data. Patients were treated with adalimumab and/or infliximab. Analysis revealed that NOD2/CARD15 mutations were not significantly associated with response to adalimumab or infliximab treatment (pooled odds ratio [OR] = 1.35, 95% confidence interval [CI]: 0.78 to 2.32, p = .278).

CONCLUSIONS

NOD2/CARD15 polymorphisms do not predict response to adalimumab and infliximab in patients with CD. However, the number of included studies was small and treatment protocols varied. Further studies are necessary to determine the role of NOD2/CARD15 polymorphisms in patients with CD.

Overcoming difficulty in diagnosis and differential diagnosis of Crohn's disease: the potential role of serological and genetic tests

Crohn's disease (CD) represents a heterogeneous group of chronic inflammatory disorders with various phenotypes. Establishing a definite diagnosis of CD should be based upon a combined assessment of clinical, endoscopic, radiological and pathological features. Although segmental disease distribution, transmural inflammation and non-caseating epithelioid granulomas have been considered as a 'hallmarks' for CD, clear diagnosis of CD in some patients has been challenging, due to overlapping endoscopic, radiographic and histologic features with other inflammatory bowel disease-like conditions. Laboratory markers (serological and genetic tests) may provide additional clues for the diagnosis and differential diagnosis of CD. This review focuses on the application of the currently available serological and genomic markers and in diagnosis and differential diagnosis of CD.

Repeated exclusive enteral nutrition in the treatment of paediatric Crohn's disease: predictors of efficacy and outcome

BACKGROUND

Exclusive enteral nutrition (EEN) induces remission and mucosal healing in children with active Crohn's disease (CD).

AIM

To compare short- and long-term outcomes of the first vs. second courses of EEN, and to identify predictors of sustained remission.

METHODS

Retrospective single centre analysis of all patients with CD (6-18 years) treated with EEN over 7.5 years. Patients were excluded if exposed to anti-TNFα or corticosteroids 3 months prior to EEN. Data included disease phenotype, activity, NOD2 genotype, laboratory indices and anthropometrics. Remission and relapse were defined by mathematically weighted Paediatric Crohn's Disease Activity Index (wPCDAI) with 1-year follow-up.

RESULTS

Of 94 patients treated with EEN, 52 fulfilled inclusion criteria (31 male, mean age 13.2 years). Azathioprine was started within the first month in 33/52 patients; 26/52 received a second EEN course. First compared to second EEN revealed higher wPCDAI at start (59 vs. 40, P < 0.0001), tended to higher remission rates after 3 months (92% vs. 77%, n.s.), but showed comparable 1-year relapse rates (67% vs. 70%, median time 231 vs. 145 days, n.s.). Disease activity, weight gain and inflammatory markers showed better improvement with first EEN. Faecal calprotectin >200 μg/g during EEN was associated with shorter remission (median time 157 vs. 287 days, n.s.). Certain NOD2 genotypes were related to higher relapse rates (92% R702W or G908R vs. 50% 1007fs vs. 60% wild-type, P < 0.01).

CONCLUSIONS

Exclusive enteral nutrition induces remission in active Crohn's disease, but efficacy tends to decrease with the second course. Despite early azathioprine use, 1-year relapse rates are high, but may be related to NOD2 genotype.