Genetic susceptibility has a more important role in pediatric-onset Crohn's disease than in adult-onset Crohn's disease

Characteristics of chronic enteropathy associated with SLCO2A1 gene (CEAS) in children, a unique type of monogenic very early-onset inflammatory bowel disease

BACKGROUND

 Chronic enteropathy associated with SLCO2A1 gene (CEAS) is a unique type of inflammatory bowel disease. CEAS is monogenic disease and is thought to develop from childhood, but studies on pediatric CEAS are scarce. We analyzed characteristics of pediatric CEAS.

METHODS

Eleven patients diagnosed with CEAS at Seoul National University Children's Hospital were identified and analyzed. Clinical data of patients were collected. Sanger sequencing of SLCO2A1 was performed on all patients.

RESULTS

Patients were diagnosed at a median age of 16.0 years (IQR 11.0 ~ 20.0), and the median age at symptoms onset was only 4.0 years (IQR 2.5 ~ 6.0). Growth delay was observed at the time of diagnosis. Patients showed multiple ulcers or strictures in the small intestine, while the esophagus and colon were unaffected in any patients. Almost half of the patients underwent small intestine resection. The major laboratory features of pediatric CEAS include iron deficiency anemia (IDA), hypoalbuminemia, and near-normal levels of C-reactive protein (CRP). Two novel mutations of SLCO2A1 were identified. The most prevalent symptoms were abdominal pain and pale face. None of the immunomodulatory drugs showed a significant effect on CEAS.

CONCLUSIONS

Pediatric CEAS typically develop from very young age, suggesting it as one type of monogenic very early onset inflammatory bowel disease. CEAS can cause growth delay in children but there is no effective treatment currently. We recommend screening for SLCO2A1 mutations to pediatric patients with chronic IDA from a young age and small intestine ulcers without elevation of CRP levels.

Inflammation and Organic Cation Transporters Novel (OCTNs)

Inflammation is a physiological condition characterized by a complex interplay between different cells handled by metabolites and specific inflammatory-related molecules. In some pathological situations, inflammation persists underlying and worsening the pathological state. Over the years, two membrane transporters namely OCTN1 (SLC22A4) and OCTN2 (SLC22A5) have been shown to play specific roles in inflammation. These transporters form the OCTN subfamily within the larger SLC22 family. The link between these proteins and inflammation has been proposed based on their link to some chronic inflammatory diseases such as asthma, Crohn's disease (CD), and rheumatoid arthritis (RA). Moreover, the two transporters show the ability to mediate the transport of several compounds including carnitine, carnitine derivatives, acetylcholine, ergothioneine, and gut microbiota by-products, which have been specifically associated with inflammation for their anti- or proinflammatory action. Therefore, the absorption and distribution of these molecules rely on the presence of OCTN1 and OCTN2, whose expression is modulated by inflammatory cytokines and transcription factors typically activated by inflammation. In the present review, we wish to provide a state of the art on OCTN1 and OCTN2 transport function and regulation in relationships with inflammation and inflammatory diseases focusing on the metabolic signature collected in different body districts and gene polymorphisms related to inflammatory diseases.

Allergy and autoimmunity in children: non-mutually exclusive diseases. A narrative review

In last decades a simultaneous increase in the prevalence of atopic and autoimmune disorders in pediatric population has been observed. Despite the Th1-Th2 paradigm, supporting the polarization of the immune system with Th1 response involved in autoimmune diseases and Th2 response leading to hypersensitivity reactions, recent evidence suggests a possible coexistence of common pathogenic pathways as result of shared immune dysregulation. Similar genes and other mechanisms such as epithelial barrier damage, gut microbiota dysbiosis and reduced number of T regs and IL-10 contribute to the onset of allergy and autoimmunity. IgA deficiency is also hypothesized to be the crosslink between celiac disease and allergy by lowering gut mucous membrane protection from antigens and allergens. The present narrative review aims to give an overview of the co-occurrence of allergic and autoimmune disorders (celiac disease, inflammatory bowel diseases, type 1 diabetes mellitus, thyroid disease, juvenile idiopathic arthritis) in pediatric population, based on the available evidence. We also highlighted the common pathogenic pathways that may underpin both. Our findings confirm that allergic and autoimmune diseases are commonly associated, and clinicians should therefore be aware of the possible coexistence of these conditions in order to ameliorate disease management and patient care. Particular attention should be paid to the association between atopic dermatitis or asthma and celiac disease or type 1 diabetes and vice versa, for therapeutic interventions. Further studies are needed to better clarify mechanisms involved in the pathogenesis and eventually identify new therapeutic strategies.

Where Are We and Where to Next?-The Future of Perianal Crohn's Disease Management

Perianal fistulizing Crohn's Disease (pCD) affects about 25% of patients with Crohn's Disease (CD). It remains a difficult entity to manage with a therapeutic ceiling of treatment success despite improving medical and surgical management. The refractory nature of the disease calls for an imminent need to better understand its immunopathogenesis and classification to better streamline our treatment options. In this article, we overview the current state of pCD management and discuss where the future of its management may lie.

A double-edged sword: DLG5 in diseases

Discs large homolog 5 (DLG5), a key member of the membrane-associated guanylate kinase (MAGUKs) family, is a scaffold molecule for signal transduction complexes and is responsible for assembling receptors and adapters. This scaffold protein stabilizes adhesion and tight bonding complexes in many organs and tissues, and is involved of maintaining epithelial polarity. Although DLG5 plays a role in normal development in mice, it has also been linked to the onset and development of several diseases, particularly Crohn's disease and various malignancies. DLG5 has been shown to impact the progression of cancer through direct or indirect interactions with H-catenin, E-cadherin, Vimentin, p53, P21, Cyclin D1, TGF-β1, AKT, Hippo, and classic G protein signaling pathways. DLG5 and DLG5 variants has been found to have a dual role in human diseases. Although it is overexpressed in pancreatic adenocarcinoma, its expression is reduced in lung, liver, breast, prostate, and bladder cancers. However, two independent studies on glioblastoma (GBM) have shown the opposite effects of DLG5. Our study evaluates the existing literature on the role of DLG5 and DLG5 variants in disease processes, and summarizes the available data on the role of DLG5 in disease based on cell experiments, clinical samples, and animal models, while highlighting its future potential in disease treatment.

Infantile-onset inflammatory bowel disease has variable long-term outcomes

Objective and aim

Infantile-onset inflammatory bowel disease (IO-IBD), defined as IBD diagnosed at age 2 years or younger, tends to be more severe and refractory to conventional treatment than IBD diagnosed at a later age. However, data about IO-IBD and its long-term follow up are limited. We thus aimed to evaluate the presentation and long-term outcomes of patients with IO-IBD in a retrospective multicenter study.

Methods

Medical records of patients diagnosed with IO-IBD in eight medical centers during 2000-2017 with at least 1-year follow up were reviewed. Demographics and disease characteristics at diagnosis including age of onset, disease phenotype and location, surgeries, medical therapy, and comorbid conditions were recorded.

Results

Twenty-three patients with IO-IBD (16 males, 70%) were identified and followed for a median (range) of 51.2 (26.0-110.3) months. The mean ages at presentation and at the last follow up were 14 ± 9.8 and 101 ± 77 months, respectively. Six (26%) patients needed ileostomy already at the time of diagnosis and 20 (87%) were treated with corticosteroids. During long-term follow up, remission was achieved in 16 (73%) patients; of whom, 3 (14%) were without medications and 7 (32%) were in remission with the use of 5-aminosalicylic acid only. One patient needed hemicolectomy and one developed a severe EBV related infection.

Conclusion

The majority of patients with IO-IBD achieved long-term remission, despite a severe disease presentation at diagnosis. Surgery rate however is high, mainly during the first months from diagnosis.

Clinical and laboratory predictors of monogenic very early onset inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract. Treatment for patients who have a monogenic cause of their IBD, often the youngest children, known as very early onset IBD (VEO-IBD), can be different from standard treatment for polygenic cases. Yet, ascertainment of these patients is difficult.

METHODS

We analyzed cases of VEO-IBD to understand the breadth of monogenic etiology and to identify clinical, laboratory, and flow cytometric correlates of this subpopulation.

RESULTS

Genetic causes of very early onset inflammatory bowel disease are highly diverse ranging from pure epithelial defects to classic T cell defects. Flow cytometry, other than testing for chronic granulomatous disease, has a low sensitivity for monogenic etiologies. Poor growth was a clinical feature associated with monogenic causality.

CONCLUSIONS

Genetic testing is, at this moment, the most robust method for the identification of monogenic cases of very early onset IBD.

Clinical Phenotypes and Outcomes in Monogenic Versus Non-monogenic Very Early Onset Inflammatory Bowel Disease

BACKGROUND AND AIMS

Over 80 monogenic causes of very early onset inflammatory bowel disease [VEOIBD] have been identified. Prior reports of the natural history of VEOIBD have not considered monogenic disease status. The objective of this study is to describe clinical phenotypes and outcomes in a large single-centre cohort of patients with VEOIBD and universal access to whole exome sequencing [WES].

METHODS

Patients receiving IBD care at a single centre were prospectively enrolled in a longitudinal data repository starting in 2012. WES was offered with enrollment. Enrolled patients were filtered by age of diagnosis <6 years to comprise a VEOIBD cohort. Monogenic disease was identified by filtering proband variants for rare, loss-of-function, or missense variants in known VEOIBD genes inherited according to standard Mendelian inheritance patterns.

RESULTS

This analysis included 216 VEOIBD patients, followed for a median of 5.8 years. Seventeen patients [7.9%] had monogenic disease. Patients with monogenic IBD were younger at diagnosis and were more likely to have Crohn's disease phenotype with higher rates of stricturing and penetrating disease and extraintestinal manifestations. Patients with monogenic disease were also more likely to experience outcomes of intensive care unit [ICU] hospitalisation, gastrostomy tube, total parenteral nutrition use, stunting at 3-year follow-up, haematopoietic stem cell transplant, and death. A total of 41 patients [19.0%] had infantile-onset disease. After controlling for monogenic disease, patients with infantile-onset IBD did not have increased risk for most severity outcomes.

CONCLUSIONS

Monogenic disease is an important driver of disease severity in VEOIBD. WES is a valuable tool in prognostication and management of VEOIBD.

Inflammatory bowel disease in primary immunodeficiency disorders is a heterogeneous clinical entity requiring an individualized treatment strategy: A systematic review

OBJECTIVE

To describe the prevalence, clinical presentation and current treatment regimens of inflammatory bowel disease (IBD) in patients with primary immunodeficiency disorders (PIDs).

METHODS

A systematic review was conducted. The following databases were searched: MEDLINE, Embase, Web of Science, the Cochrane Library and Google Scholar.

RESULTS

A total of 838 articles were identified, of which 36 were included in this review. The prevalence of IBD in PIDs ranges between 3.4% and 61.2%, depending on the underlying PID. Diarrhea and abdominal pain were reported in 64.3% and 52.4% of the patients, respectively. Colon ulceration was the most frequent finding on endoscopic evaluation, while cryptitis, granulomas, ulcerations and neutrophilic/lymphocytic infiltrates were the most frequently reported histopathological abnormalities. Described treatment regimens included oral corticosteroids and other oral immunosuppressive agents, including mesalazine, azathioprine and cyclosporin, leading to clinical improvement in the majority of patients. In case of treatment failure, biological therapies including TNF- α blocking agents, are considered.

CONCLUSIONS

The overall prevalence of IBD in patients with PID is high, but varies between different PIDs. Physicians should be aware of these complications and focus on characteristic symptoms to reduce diagnostic delay and delay in initiation of treatment. Treatment of IBD in PIDs depends on severity of symptoms and may differ between various PIDs based on distinct underlying pathogenesis. An individualized diagnostic and therapeutic approach is therefore warranted.

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.

North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Position Paper on the Evaluation and Management for Patients With Very Early-onset Inflammatory Bowel Disease

The rate of pediatric inflammatory bowel disease (IBD) has been increasing over the last decade and this increase has occurred most rapidly in the youngest children diagnosed <6 years, known as very early-onset inflammatory bowel disease (VEO-IBD). These children can present with more extensive and severe disease than older children and adults. The contribution of host genetics in this population is underscored by the young age of onset and the distinct, aggressive phenotype. In fact, monogenic defects, often involving primary immunodeficiency genes, have been identified in children with VEO-IBD and have led to targeted and life-saving therapy. This position paper will discuss the phenotype of VEO-IBD and outline the approach and evaluation for these children and what factors should trigger concern for an underlying immunodeficiency. We will then review the immunological assays and genetic studies that can facilitate the identification of the underlying diagnosis in patients with VEO-IBD and how this evaluation may lead to directed therapies. The position paper will also aid the pediatric gastroenterologist in recognizing when a patient should be referred to a center specializing in the care of these patients. These guidelines are intended for pediatricians, allied health professionals caring for children, pediatric gastroenterologists, pediatric pathologists, and immunologists.

Neonatal Crohn's disease with Oral ulcer as the first symptom caused by a compound heterozygote mutation in IL-10RA: a case report

Objective

To investigate the clinical and genetic characteristics of neonatal Crohn's disease (CD), improve recognition of neonatal CD, and reduce the number of patients that are missed or misdiagnosed.

Methods

A 10-day-old Chinese girl with oral ulcers was admitted to the Department of Neonatology. She later developed a rash and perianal disease, but without diarrhea and stool abnormalities. The patient and her parents underwent next-generation sequencing.

Results

The results showed that the patient carries a compound heterozygous mutation in the interleukin-10 receptor A (IL-10RA) (NM_001558.3) gene. One heterozygous mutation was c.301 c > T, P. (Arg 101 Trp) in exon 3 of IL-10RA (a missense mutation), and the other was c. 537G > A, P. (Thr 179 =) in exon 4 of IL 10RA (a synonymous mutation). The patient's father also carries the c.301 c > T, P. (Arg 101 Trp) heterozygous mutation in exon 3 of IL-10RA, whereas her mother carries the c.537G > A, P. (Thr 179 =) heterozygous mutation in exon 4 of IL-10RA.

Conclusions

The results show that a compound heterozygous mutation in IL-10RA is associated with neonatal CD. Oral ulcers with a rash and perianal disease may be an early symptom of neonatal CD; therefore, such patients should undergo genetic identification as soon as possible.

Polymorphisms of the TNF Gene and Three Susceptibility Loci Are Associated with Crohn's Disease and Perianal Fistula Crohn's Disease: A Study among the Han Population from South China

Background

Although 90 susceptibility loci of Crohn’s disease (CD) have been confirmed in the Asian population, susceptibility genes for perianal fistula of CD (pCD) in this population remain unknown. This study explored susceptibility genes for CD and pCD in the Han population from South China.

Material/Methods

In total, 490 patients diagnosed with CD between July 2012 and June 2016 at the Sixth Affiliated Hospital of Sun Yat-sen University were included and divided into the CD group (n=240) and the pCD group (n=250). The healthy control group was composed of 260 volunteers. Peripheral blood samples were taken, and single nucleotide polymorphism (SNP) locus sequencing was used to screen for susceptibility loci. SNPs were sequenced using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Results

Nine SNPs in TNFSF1 on chromosome 9 were associated with CD. Among them, the rs6478106 locus is a risk locus for CD. The distribution frequency of the T allele of the rs6478106 SNP was significantly different between cases and controls (32.49% versus 18.27%, P<0.001). Rs72553867, located in the IRGM gene on chromosome 5, rs4409764, located in the NKX2–3 gene on chromosome 10, and rs3731772, located in the AOX1 gene on chromosome 2, were susceptibility factors for pCD. Nine SNPs located in TNFSF15 on chromosome 9 were related to CD in Han individuals from Southern China.

Conclusions

The rs6478106 T allele is associated with the risk of CD in the investigated population. SNPs rs72553867 (IRGM gene), rs4409764 (NKX2–3 gene), and rs3731772 (AOX1 gene) increase the risk of pCD.

Distinct Histopathological Features at Diagnosis of Very Early Onset Inflammatory Bowel Disease

BACKGROUND AND AIMS

Children with very early onset inflammatory bowel disease [VEO-IBD] represent a unique cohort, often with a severe phenotype that is refractory to conventional medications, and some cases have underlying primary immunodeficiencies. Previous work has identified distinct histopathological patterns in the gastrointestinal tract in patients with primary immunodeficiencies. The aim of this study is to characterise the diagnostic histological findings in patients with VEO-IBD as compared with older onset paediatric IBD, and determine if there are unique pathological changes that can shed light on the driving forces of the disease, particularly immunodeficiencies.

METHODS

Clinical retrospective chart review, including disease characteristics and endoscopic findings, was performed on all included subjects. Two paediatric pathologists reviewed biopsies from diagnostic upper endoscopies and colonoscopies of subjects with very early onset inflammatory bowel disease and older onset inflammatory bowel disease, to evaluate for the presence of 11 histological features previously associated with inflammatory bowel disease and primary immunodeficiencies.

RESULTS

The diagnostic gastrointestinal biopsies of subjects with very early onset inflammatory bowel disease differed from those in older onset paediatric IBD, demonstrated by increased frequency of apoptosis, severe chronic architectural changes, small intestine villous blunting, and eosinophils in the crypts, lamina propria, and surface epithelium.

CONCLUSIONS

The diagnostic biopsies of children with very early onset inflammatory bowel disease can identify characteristic features that may be important in guiding the diagnostic work-up in this population.

Bayesian Approximate Kernel Regression with Variable Selection

Nonlinear kernel regression models are often used in statistics and machine learning because they are more accurate than linear models. Variable selection for kernel regression models is a challenge partly because, unlike the linear regression setting, there is no clear concept of an effect size for regression coefficients. In this paper, we propose a novel framework that provides an effect size analog for each explanatory variable in Bayesian kernel regression models when the kernel is shift-invariant - for example, the Gaussian kernel. We use function analytic properties of shift-invariant reproducing kernel Hilbert spaces (RKHS) to define a linear vector space that: (i) captures nonlinear structure, and (ii) can be projected onto the original explanatory variables. This projection onto the original explanatory variables serves as an analog of effect sizes. The specific function analytic property we use is that shift-invariant kernel functions can be approximated via random Fourier bases. Based on the random Fourier expansion, we propose a computationally efficient class of Bayesian approximate kernel regression (BAKR) models for both nonlinear regression and binary classification for which one can compute an analog of effect sizes. We illustrate the utility of BAKR by examining two important problems in statistical genetics: genomic selection (i.e. phenotypic prediction) and association mapping (i.e. inference of significant variants or loci). State-of-the-art methods for genomic selection and association mapping are based on kernel regression and linear models, respectively. BAKR is the first method that is competitive in both settings.

Association of IL23R Variants With Crohn's Disease in Korean Children

Background: The interleukin 23 receptor gene (IL23R) is strongly associated with Crohn's disease (CD). It is unknown whether genetic variations in IL23R determine susceptibility for pediatric CD in Asian populations. Here, we investigated the association between IL23R variants and CD in Korean children. Methods: Four single nucleotide polymorphisms (SNPs) of IL23R [rs76418789 (G149R), rs1004819, rs7517847, and rs1495965] were genotyped in 141 children with CD and 150 controls using DNA direct sequencing. The risk allele and genotype frequencies were compared between patients and controls. The association between clinical phenotypes and genotypes of patients was also analyzed. Results: Two IL23R SNPs, rs76418789 (G149R), and rs1495965, were associated with CD in Korean pediatric patients as defense and risk loci, respectively. The odds ratio (OR) for rs76418789 (G149R) and rs1495965 was 0.409 (95% confidence interval [CI], 0.177-0.944; p = 0.031) and 1.484 (95% CI, 1.070-2.059; p = 0.018), respectively. Patients with the homozygous G allele of rs1495965 showed higher CD risk than those with other genotypes (GG vs. AA: OR, 2.256; 95% CI, 1.136-4.478; p = 0.019; GG vs. GA+AA: OR, 2.000; 95% CI, 1.175-3.404; p = 0.010). Additionally, they were more likely to have relatively invasive disease behavior of stenosis and/or penetration than simple inflammation (OR, 2.297; 95% CI, 1.065-4.950; p = 0.032). Conclusions: This is the first study reporting IL23R variants in Asian pediatric patients with CD. IL23R was significantly associated with Korean pediatric CD, and the rs1495965 may influence the clinical features of CD in Korean children.

Genomic and Immunologic Drivers of Very Early-Onset Inflammatory Bowel Disease

PURPOSE OF REVIEW

Inflammatory bowel disease (IBD) is a multifactorial disease caused by dysregulated immune responses to commensal or pathogenic intestinal microbes, resulting in chronic intestinal inflammation. However, a subset of patients with IBD diagnosed <6 years of age, known as very early-onset (VEO)-IBD, can be phenotypically and genetically distinct from older onset IBD. We aim to review the clinical presentation of children with VEO-IBD and recent discoveries that point to the underlying genomic and immunologic drivers of disease, and the significant impact on our therapeutic decisions.

RECENT FINDINGS

VEO-IBD is increasing in incidence and is associated with more severe disease, aggressive progression, and poor response to most conventional therapies. This article will review some of the genetic findings in this population and the subsequent impact on therapy, with targeted approaches.

SUMMARY

Children with VEO-IBD may present with a different phenotype and more severe disease than older children and adults. An integrated approach combining genetics, immunology, and traditional IBD evaluations can lead to the identification of causal defects that directly impact management. These strategies can also be employed in older onset refractory IBD.

Inflammatory Bowel Disease: What Very Early Onset Disease Teaches Us

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract, of which ulcerative colitis and Crohn's disease are the 2 most prevailing entities. Very early onset IBD (VEO-IBD) children diagnosed with IBD under age 6 years. Although the etiology of IBD is mostly unknown, it involves a complex interaction among host genetics, microbiota, environmental factors, and aberrant immune responses. Advances in the understanding of the genetic contribution, which appears to be much more significant in younger children, gives us a useful insight into the pathogenesis and potential future therapeutic targets in IBD.

Is top-down therapy a more effective alternative to conventional step-up therapy for Crohn's disease?

The management of Crohn's disease involves immunosuppressive protocols in a step-up approach that progresses through a therapeutic pyramid with several tiers of medication. Medications at the top are considered more potent but present greater risk. A new top-down approach to therapy inverts this procedure, using top-tier drugs for initial treatment. A critical appraisal of the current literature relating to top-down therapy was performed to evaluate its merit. A literature search was conducted on PubMed, Ovid, and PubMed Central to identify studies of the efficacy of top-down therapy. Papers were appraised critically using the Scottish Intercollegiate Guidelines Network score to evaluate current evidence for the use of top-down therapy. Nineteen studies were identified, including six randomized controlled trials, thirteen cohort studies, and two cost-benefit studies. Early combined therapy involving both biologics and immunomodulators was found to be effective at improving patient outcomes; however, early biologics alone were not shown to have a clear benefit over step-up therapy. Likewise, the early use of immunomodulators alone showed inconsistent results with respect to efficacy in terms of both remission and surgical outcomes. Evidence for application in pediatric populations was also inconclusive. The cost-benefit analyses found that top-down therapy merits investigation, as it proved to be economical given current data. Top-down therapy has the potential of being a viable alternative to step-up therapy, but further studies are needed to determine the most appropriate patients to receive this treatment.

Childhood-onset inflammatory bowel diseases associated with mutation of Wiskott-Aldrich syndrome protein gene

AIM

To screen primary immunodeficiency, Wiskott-Aldrich syndrome (WAS), and chronic granulomatous disease (CGD) among children with inflammatory bowel disease (IBD).

METHODS

This was a single-center retrospective study. Eighteen children with IBD were investigated. We analyzed their expression of Wiskott-Aldrich syndrome protein (WASP) in lymphocytes and superoxide generation in phagocytes using flow cytometry. When the expression of WASP or superoxide generation was low or absent, we performed genetic analysis to determine the cause of this.

RESULTS

Eighteen patients were classified as having ulcerative colitis (n = 10), Crohn’s disease (n = 5), or IBD-unclassified (n = 3). In total, three patients revealed low expression of WASP associated with a WAS gene c.1378 C>T p.Pro460Ser mutation, which has previously been reported as a pathogenic mutation in WAS and X-linked thrombocytopenia. However, with respect to the major symptoms of WAS, none of these three patients showed either thrombocytopenia or increased susceptibility to infection, but one patient showed generalized eczema. No CGD patients were discovered in this study.

CONCLUSION

Despite the lack of typical clinical manifestations of WAS, low expression of WASP could be associated with the pathogenesis of a subtype of IBD patients.

Genetic profile of patients with early onset inflammatory bowel disease

Inflammatory Bowel disease (IBD) is a widespread pathological condition with clinical heterogeneity and with different levels of severity. Although IBD usually occurs in young adults, onset in childhood and infancy are described in patients within the 10th and second year of age. By genome-wide association studies and meta-analysis, several genetic loci have been identified associated with an increased risk of developing IBD in Western populations with variants that may alter the normal mucosal immunity in the gastrointestinal tract. The clinical complexity and the heterogeneity of the IBD phenotype probably reflect the presence of genetic heterogeneity where different genes or combinations of them may be involved, together with environmental factors. We hypothesized that patients with early onset IBD could have either more severe genetic variants in genes associated with IBD or multiple variants in different genes. Under the multifactorial diseases is crucial to consider the small contribution of a single variant in all not only to other small variations in the same gene but also in different genes belonging to the same pathway. We performed direct gene sequencing looking for 94 variations in NOD2, ATG16L1, IL23R, IL10R, IL10 and XIAP genes previously shown as correlated with IBD both in multifactorial and in Mendelian models. All variants identified are known in literature as being associated with IBD except for three variants in the genes NOD2, IL10 and IL10RB that even though present in online databases have never been involved in association studies on IBD patients. Moreover, we coupled genetic variants identification with an accurate "in silico" analysis to verify their predictive impact on the protein structure and function. The in-silico prediction of these variants results as benign therefore even if they exhibit a very low frequency in control population being benign, they cannot be considered pathogenic as monogenic disease but fall within the multifactorial range. The variants identified in our study partially reflect the association data described in the literature but there are no significant differences with the onset of disease (VEO vs EO-IBD).

The role of monogenic disease in children with very early onset inflammatory bowel disease

PURPOSE OF REVIEW

Inflammatory bowel disease (IBD) is a multifactorial disease caused by dysregulated immune responses to commensal or pathogenic intestinal microbes, resulting in chronic intestinal inflammation. Patients diagnosed with IBD occurring before the age of 5 are a unique population, known as very early onset (VEO)-IBD and can be phenotypically and genetically distinct from older-onset IBD. We aim to review the clinical presentation of children with VEO-IBD and recent discoveries that point to genomic drivers of disease that may impact our therapeutic decisions.

RECENT FINDINGS

VEO-IBD is increasing in incidence and is associated with more severe disease, aggressive progression and poor response to most conventional therapies. This article will review the advances in sequencing technology that have led to identification of novel gene variants associated with disease and potentially new targeted therapeutic options.

SUMMARY

Children with VEO-IBD may present with a different phenotype and more severe disease than older children and adults. Identification of the causal gene or pathways, these children may allow for true precision medicine with targeted therapy and improved disease course.

The DNA methylation landscape of CD4+ T cells in oligoarticular juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is presumed to be driven by an adverse combination of genes and environment. Epigenetic processes, including DNA methylation, act as a conduit through which the environment can regulate gene activity. Altered DNA methylation has been associated with adult autoimmune rheumatic diseases such as rheumatoid arthritis, but studies are lacking for paediatric autoimmune rheumatic diseases including JIA. Here, we performed a genome-scale case-control analysis of CD4⁺ T cell DNA methylation from 56 oligoarticular JIA (oJIA) cases and 57 age and sex matched controls using Illumina HumanMethylation450 arrays. DNA methylation at each array probe was tested for association with oJIA using RUV (Remove Unwanted Variation) together with a moderated t-test. Further to this 'all-inclusive' analysis, we stratified by age at diagnosis (≤6yrs, >6yrs) and by sex as potential sources of heterogeneity. Following False Discovery Rate (FDR) adjustment, no probes were associated with oJIA in the all-inclusive, >6yrs-diagnosed, or sex-stratified analyses, and only one probe was associated with oJIA in the ≤6yrs-diagnosed analysis. We attempted technical validation and replication of 14 probes (p_unadj<0.01) at genes of known/potential relevance to disease. At VPS53, we demonstrated a regional shift towards higher methylation in oJIA (all-inclusive) compared to controls. At REEP3, where polymorphism has been previously associated with JIA, we demonstrated higher DNA methylation in male oJIA compared to male controls. This is the most comprehensive JIA case-control analysis of DNA methylation to date. While we have generated some evidence of altered methylation in oJIA, substantial differences are not apparent in CD4⁺ T cells. This may indicate a lesser relevance of DNA methylation levels in childhood, compared to adult, rheumatic disease.

Crohn's Disease: Genetics Update

Since the discovery of the first Crohn's disease (CD) gene NOD2 in 2001, 140 genetic loci have been found in whites using high-throughput genome-wide association studies. Several genes influence the CD subphenotypes and treatment response. With the observations of increasing prevalence in Asia and developing countries and the incomplete explanation of CD variance, other underexplored areas need to be integrated through novel methodologies. Algorithms that incorporate specific genetic risk alleles with other biomarkers will be developed and used to predict CD disease course, complications, and response to specific therapies, allowing precision medicine to become real in CD.

Nutritional Therapy in Very Early-Onset Inflammatory Bowel Disease: A Case Report

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract caused by a dysregulated immune response to the fecal microbiota. Very early-onset inflammatory bowel disease (VEO-IBD) refers to a subgroup of pediatric patients with IBD diagnosed before 6 years of age. This subgroup is often characterized by increased severity, aggressive progression, strong family history of IBD, and often poor response to conventional treatments. Nutritional therapies have been utilized to treat IBD, but their role in VEO-IBD is unclear. Disease behavior in VEO-IBD is often different from disease in adolescents and adults, as it is often restricted to the colon and refractory to standard medical therapies. Up to 25% of VEO-IBD patients have an identified underlying immunodeficiency, which may impact response to therapy. While specific mutations in interleukin 10 (IL-10), the IL-10 receptor (IL-10R), and mutations in NCF2, XIAP, LRBA, and TTC7 have been identified in VEO-IBD, polymorphisms in these genes are also associated with increased risk of developing IBD in adolescence or adulthood. We describe two cases in which infants presenting with VEO-IBD achieved clinical remission using exclusive enteral nutrition, a formula-based diet which has been shown to induce remission in older children with active Crohn's disease.

Genetic and environmental factors significant for the presentation and development of inflammatory bowel disease

OBJECTIVES

The aim of the study was to evaluate associations between inflammatory bowel disease (IBD) presentation and variants in NOD2, TLR4, TNF-α, IL-6, IL-1β, and IL-RN genes in order to identify possible environmental factors that may affect IBD occurrence, investigate potential predictors for surgical treatment of IBD, and correlate the presence of granulomas in biopsy specimens with clinical characteristics of Crohn's disease (CD) patients.

PATIENTS AND METHODS

We genotyped 167 IBD patients using PCR-based methodology and tested for disease genotype-phenotype associations.

RESULTS

In CD patients ileal localization of disease was more frequent in NOD2 variant carriers. Ileal CD was associated with IL-6 GC+CC genotypes, identifying C allele as a possible marker of increased risk for ileal CD. In CD patients a positive family history for IBD was related to earlier onset of disease, higher risk for CD-related surgery, and appendectomy. CD patients who are TLR4 299Gly carriers are at higher risk for surgery at onset of the disease compared with TLR4 299Asp variant carriers. The presence of granuloma in biopsy specimens was more frequent in patients in whom a diagnosis of CD was made during emergency surgery. Multivariate analysis showed that CD carriers of the 299Gly allele had a 4.6-fold higher risk for emergency surgery before CD diagnosis is established compared with noncarriers, suggesting an aggressive disease course. Granuloma in endoscopic biopsies is detected 5.4-fold more frequently in patients treated surgically at the time of diagnosis.

CONCLUSION

Genetic variants together with epidemiological and clinical data of IBD patients could potentially be used as predictors of the disease course.

Fistulizing Crohn's Disease

Fistulas still represent one of the most important complications in patients with Crohn’s disease (CD). At least one third of CD patients suffer from fistulas during their disease course and amongst them longstanding remission of complex fistulas occurs only in about one third. So far, fistula pathogenesis is only partially understood. From a histopathological view, a fistula is a tube covered by flat epithelial cells. Current research suggests that the driving force for fistula development is epithelial-to-mesenchymal transition (EMT). Around the fistula, high levels of tumor necrosis factor (TNF), IL-13, and TGFβ can be detected and recent studies indicated an involvement of the intestinal microbiota. Fistula diagnosis requires clinical and surgical assessment, radiologic investigations, e.g., magnet resonance imaging and endoscopy. Routine medical treatment of fistulas includes antibiotics, immunosuppressives, and anti-TNF antibodies. There is no well-established role for calcineurin inhibitors in fistula treatment, corticosteroids appear to be even contra-productive. A promising novel approach might be the application of adipose tissue-derived or bone marrow-derived mesenchymal stem cells that have been studied recently. Due to insufficient efficacy of medical treatment and recurrence of fistulas, surgical interventions are frequently necessary. Further research is needed to better understand fistula pathogenesis aiming to develop novel treatment option for our patients.

The NOD2-Smoking Interaction in Crohn's Disease is likely Specific to the 1007fs Mutation and may be Explained by Age at Diagnosis: A Meta-Analysis and Case-Only Study

Background

NOD2 and smoking are risk factors for Crohn's disease. We meta-analyzed NOD2-smoking interactions in Crohn's disease (Phase 1), then explored the effect of age at diagnosis on NOD2-smoking interactions (Phase 2).

Methods

Phase 1: MEDLINE and EMBASE were searched for studies (n = 18) providing data on NOD2 and smoking in Crohn's disease. NOD2-smoking interactions were estimated using odds ratios (ORs) and 95% confidence intervals (CIs) calculated using random effects models. Phase 2: A case-only study compared the proportion of smokers and carriers of the 1007 fs variant across ages at diagnosis (≤ 16, 17–40, > 40 years).

Findings

Phase 1: Having ever smoked was less common among carriers of the 1007 fs variant of NOD2 (OR 0.74, 95%CI:0.66–0.83). There was no interaction between smoking and the G908R (OR 0.96, 95%CI:0.82–1.13) or the R702W variant (OR 0.89, 95%CI:0.76–1.05). Phase 2: The proportion of patients (n = 627) carrying the 1007 fs variant decreased with age at diagnosis (≤ 16 years: 15%; 17–40: 12%; > 40: 3%; p = 0.003). Smoking was more common in older patients (≤ 16 years: 4%; 17–40: 48%; > 40: 71%; p < 0.001).

Interpretation

The negative NOD2-smoking interaction in Crohn's disease is specific to the 1007 fs variant. However, opposing rates of this variant and smoking across age at diagnosis may explain this negative interaction.

•

There is a negative interaction between NOD2 smoking in Crohn's disease and it is specific to the 1007fs variant.

•

With increasing age, the prevalence of the 1007fs variant decreases and exposure to cigarette smoke increases.

•

Contrasting trends in the 1007fs variant and cigarette smoking may explain the negative NOD2-smoking interaction.

We reviewed 18 studies evaluating NOD2-smoking interactions in Crohn's disease. Only the 1007fs variant interacted with smoking. Smokers with this mutation were less likely to develop Crohn's disease. We then conducted a study of 627 patients with Crohn's disease, which showed that the 1007fs variant was common in young patients and rare in older patients, whereas smoking was more common among older patients. The decreasing prevalence of 1007fs mutation and increasing exposure to smoking as age of diagnosis advances may explain the negative interaction between NOD2 and smoking observed in our meta-analysis. Our study highlights the challenges of identifying gene-environment interactions.

Meta-analysis of associations between DLG5 R30Q and P1371Q polymorphisms and susceptibility to inflammatory bowel disease

Growing evidence from recent studies has demonstrated an association between inflammatory bowel disease (IBD) susceptibility and two polymorphisms of DLG5 R30Q (rs1248696) and P1371Q (rs2289310), but the results remain controversial. We conducted a meta-analysis including a total of 22 studies with 10,878 IBD patients and 7917 healthy controls for R30Q and 5277 IBD cases and 4367 controls for P1371Q in order to systematically assess their association with the disease. The results indicated that R30Q was significantly associated with reduced susceptibility to IBD in Europeans by allelic and dominant comparisons, but not in overall population. No significant association was found between R30Q and Crohn's disease (CD) or ulcerative colitis (UC). P1371Q was associated with increased risk of IBD in Europeans and Americans. On the contrary, a decreased risk of IBD was observed in Asian population for P1371Q. In disease subgroup analysis, we found that P1371Q was also significantly associated with CD, but this relationship was not present for UC. In conclusion, our results strongly suggest that the both polymorphisms of DLG5 are correlated with IBD susceptibility in an ethnic-specific manner. Additional well-designed studies with large and diverse cohorts are needed to further strengthen our findings.

Epistatic interaction between TLR4 and NOD2 in patients with Crohn's Disease: relation with risk and phenotype in a Spanish cohort

Crohn's Disease is one of the two major forms of the Inflammatory Bowel Diseases and, although the etiology is not completely understood, the confluence of environmental and genetic factors has been demonstrated. The aim of this study was to determine the distribution of TLR4 variants in a Spanish cohort of Crohn's Disease patients and their relation with phenotype and common NOD2 variants. A total of 371 Crohn's Disease (CD) patients and 636 healthy controls (HC) were included. Single Nucleotide Polimorphisms (SNPs) in TLR4 (D299G and T399I) and NOD2 (R702W and G908R) detection was performed by a Taqman(®) Allelic Discrimination Assay. 1007insC NOD2 variant was analyzed using a PCR combined with fluorescent technology and the different alleles were determined depending on the PCR products size. D299G and T399I were related to CD only in patients carrying NOD2 variants (NOD2+/TLR4+ haplotype) (p=0.036; OR=1.924), increasing the risk to develop CD when 1007insC and TLR4 variants were both present (OR=4.886). We also described a strong association between mutant NOD2 and CD risk (p<0.001, OR=3.214). R702W, G908R and 1007insC were associated when they were considered separately (p<0.001; p=0.002; p<0.001, respectively). Moreover, the patients carrying any mutant D299G or T399I polymorphisms were predisposed to develop a stricturing disease (p=0.013; OR=2.391), especially in the presence of NOD2 mutation (p=0.002; OR=4.989). In this study, ileal disease was also associated with the presence of at least one NOD2 susceptibility allele (p=0.001; OR=3.838) and, the risk of ileal CD was increased if TLR4 variants were presents (p<0.050; OR=4.160). TLR4 variants were related to bowel perforation, independently of NOD2.

Results of the Fifth Scientific Workshop of the ECCO (II): Pathophysiology of Perianal Fistulizing Disease

The fifth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of fistulas to the disease course of patients with Crohn's disease (CD). The objectives were to reach a better understanding of the pathophysiological mechanisms underlying the formation of CD fistulas; to identify future topics in fistula research that could provide insights into pathogenesis; to develop novel therapeutic approaches; and to review current therapeutic strategies (with clarification of existing approaches to prevention, diagnosis and treatment). The results of the workshop are presented in two separate manuscripts. This manuscript describes current state-of-the-art knowledge about fistula pathogenesis, including the roles of epithelial-to-mesenchymal transition and cytokine matrix remodelling enzymes, and highlights the common association between fistulas and stenosis in CD. The review also considers the possible roles that genetic predisposition and intestinal microbiota play in fistula development. Finally, it proposes future directions and needs for fistula research that might substantially increase our understanding of this complex condition and help unravel novel therapeutic strategies and specific targets for treatment. Overall, it aims to highlight unanswered questions in fistula research and to provide a framework for future research work.

Exome sequencing analysis reveals variants in primary immunodeficiency genes in patients with very early onset inflammatory bowel disease

BACKGROUND & AIMS

Very early onset inflammatory bowel disease (VEO-IBD), IBD diagnosed at 5 years of age or younger, frequently presents with a different and more severe phenotype than older-onset IBD. We investigated whether patients with VEO-IBD carry rare or novel variants in genes associated with immunodeficiencies that might contribute to disease development.

METHODS

Patients with VEO-IBD and parents (when available) were recruited from the Children's Hospital of Philadelphia from March 2013 through July 2014. We analyzed DNA from 125 patients with VEO-IBD (age, 3 wk to 4 y) and 19 parents, 4 of whom also had IBD. Exome capture was performed by Agilent SureSelect V4, and sequencing was performed using the Illumina HiSeq platform. Alignment to human genome GRCh37 was achieved followed by postprocessing and variant calling. After functional annotation, candidate variants were analyzed for change in protein function, minor allele frequency less than 0.1%, and scaled combined annotation-dependent depletion scores of 10 or less. We focused on genes associated with primary immunodeficiencies and related pathways. An additional 210 exome samples from patients with pediatric IBD (n = 45) or adult-onset Crohn's disease (n = 20) and healthy individuals (controls, n = 145) were obtained from the University of Kiel, Germany, and used as control groups.

RESULTS

Four hundred genes and regions associated with primary immunodeficiency, covering approximately 6500 coding exons totaling more than 1 Mbp of coding sequence, were selected from the whole-exome data. Our analysis showed novel and rare variants within these genes that could contribute to the development of VEO-IBD, including rare heterozygous missense variants in IL10RA and previously unidentified variants in MSH5 and CD19.

CONCLUSIONS

In an exome sequence analysis of patients with VEO-IBD and their parents, we identified variants in genes that regulate B- and T-cell functions and could contribute to pathogenesis. Our analysis could lead to the identification of previously unidentified IBD-associated variants.

Association of single nucleotide polymorphism rs3792876 in SLC22A4 gene with autoimmune thyroid disease in a Chinese Han population

Background

The autoimmune thyroid diseases (AITD), including Graves’ disease (GD) and Hashimoto’s thyroiditis (HT), are caused by interactions between susceptibility genes and environmental triggers. Single nucleotide polymorphisms (SNPs) of Solute carrier family 22, member 4 (SLC22A4) have been shown to be associated with several autoimmune diseases, including Crohn’s disease (CD) and rheumatoid arthritis (RA). The aim of this study is to investigate whether SNP rs3792876 in the SLC22A4 gene is associated with GD, HT and AITD in a Chinese Han population.

Methods

In this study, we collected specimens from 553 Chinese Han individuals of 92 AITD pedigrees in 10 cities in Liaoning province, China (80 GD pedigrees, 478 members; 12 HT pedigrees, 75 members). SNP rs3792876 was genotyped using the TaqMan allelic discrimination assay. Hardy-Weinberg Equilibrium tests were performed among founders of the pedigrees using Haploview software. Family-based association tests performed using FBAT software.

Results

No deviation from Hardy-Weinberg equilibrium was observed (p > 0.05). There were not significant association between the SLC22A4 gene polymorphism (rs3792876) and GD, HT and AITD was found.

Conclusions

These results suggest a lack of association between the SLC22A4 gene polymorphism rs3792876 and susceptibility to GD, HT and AITD in a Chinese Han population.

Clinical Presentation and Five-Year Therapeutic Management of Very Early-Onset Inflammatory Bowel Disease in a Large North American Cohort

OBJECTIVE

To evaluate the presentation, therapeutic management, and long-term outcome of children with very early-onset (VEO) (≤ 5 years of age) inflammatory bowel disease (IBD).

STUDY DESIGN

Data were obtained from an inception cohort of 1928 children with IBD enrolled in a prospective observational registry at multiple centers in North America.

RESULTS

One hundred twelve children were ≤ 5 years of age with no child enrolled at <1 year of age. Of those, 42.9% had Crohn's disease (CD), 46.4% ulcerative colitis (UC), and 10.7% had IBD-unclassified. Among the children with CD, children 1-5 years of age had more isolated colonic disease (39.6%) compared with 6- to 10-year-olds (25.3%, P = .04), and 11- to 16-year-olds (22.3%, P < .01). The change from a presenting colon-only phenotype to ileocolonic began at 6-10 years. Children 1-5 years of age with CD had milder disease activity (45.8%) at diagnosis compared with the oldest group (28%, P = .01). Five years postdiagnosis, there was no difference in disease activity among the 3 groups. However, compared with the oldest group, a greater proportion of 1- to 5-year-olds with CD were receiving corticosteroids (P < .01) and methotrexate (P < .01), and a greater proportion of 1- to 5-year-olds with UC were receiving mesalamine (P < .0001) and thiopurine immunomodulators (P < .0002).

CONCLUSIONS

Children with VEO-CD are more likely to have mild disease at diagnosis and present with a colonic phenotype with change to an ileocolonic phenotype noted at 6-10 years of age. Five years after diagnosis, children with VEO-CD and VEO-UC are more likely to have been administered corticosteroids and immunomodulators despite similar disease activity in all age groups. This may suggest development of a more aggressive disease phenotype over time.

Maintaining intestinal health: the genetics and immunology of very early onset inflammatory bowel disease

Inflammatory bowel disease (IBD) is a multifactoral disease caused by dysregulated immune responses to commensal or pathogenic microbes in the intestine, resulting in chronic intestinal inflammation. An emerging population of patients with IBD occurring before the age of 5 represent a unique form of disease, termed Very Early Onset (VEO)-IBD, which is phenotypically- and genetically-distinct from older-onset IBD. VEO-IBD is associated with increased disease severity, aggressive progression and poor responsiveness to most conventional therapies. Further investigation into the causes and pathogenesis of VEO-IBD will help improve treatment strategies, and may lead to a better understanding of the mechanisms that are essential to maintain intestinal health or provoke the development of targeted therapeutic strategies to limit intestinal disease. Here we discuss the phenotypic nature of VEO-IBD, the recent identification of novel gene variants associated with disease, and functional immunologic studies interrogating the contribution of specific genetic variants to the development of chronic intestinal inflammation.

Dissecting Allele Architecture of Early Onset IBD Using High-Density Genotyping

Background

The inflammatory bowel diseases (IBD) are common, complex disorders in which genetic and environmental factors are believed to interact leading to chronic inflammatory responses against the gut microbiota. Earlier genetic studies performed in mostly adult population of European descent identified 163 loci affecting IBD risk, but most have relatively modest effect sizes, and altogether explain only ~20% of the genetic susceptibility. Pediatric onset represents about 25% of overall incident cases in IBD, characterized by distinct disease physiology, course and risks. The goal of this study is to compare the allelic architecture of early onset IBD with adult onset in population of European descent.

Methods

We performed a fine mapping association study of early onset IBD using high-density Immunochip genotyping on 1008 pediatric-onset IBD cases (801 Crohn’s disease; 121 ulcerative colitis and 86 IBD undetermined) and 1633 healthy controls. Of the 158 SNP genotypes obtained (out of the 163 identified in adult onset), this study replicated 4% (5 SNPs out of 136) of the SNPs identified in the Crohn’s disease (CD) cases and 0.8% (1 SNP out of 128) in the ulcerative colitis (UC) cases. Replicated SNPs implicated the well known NOD2 and IL23R. The point estimate for the odds ratio (ORs) for NOD2 was above and outside the confidence intervals reported in adult onset. A polygenic liability score weakly predicted the age of onset for a larger collection of CD cases (p< 0.03, R²= 0.007), but not for the smaller number of UC cases.

Conclusions

The allelic architecture of common susceptibility variants for early onset IBD is similar to that of adult onset. This immunochip genotyping study failed to identify additional common variants that may explain the distinct phenotype that characterize early onset IBD. A comprehensive dissection of genetic loci is necessary to further characterize the genetic architecture of early onset IBD.

Differences between adults and children: genetics and beyond

Clinical observations and epidemiological studies have highlighted some important differences in disease course and phenotypes between pediatric inflammatory bowel disease (IBD) and adult-onset IBD. Also from a therapeutic angle, the approach to young-onset IBD is different with a more rapid introduction of azathioprine and a high threshold for long and systemic steroid use, which may affect bone mineral density and growth. The observed clinical differences have been an area of scientific research and genetic studies have been the focus of attention. Specific candidate gene studies as well as genome-wide association studies have been performed in pediatric IBD. With the exception of very early-onset IBD occurring before the age of 2 years; no overt differences in genetic susceptibility have been identified. In contrast, very early-onset IBD seems in particular to be a genetic disease with defects in the IL10 signaling pathway being the principal example. This review aims to answer some straightforward questions arising in this topic by giving concise information.

Toll-like receptor 4 Asp299Gly and Thr399Ile polymorphisms: New data and a meta-analysis

Background

The pathogenesis of inflammatory bowel disease (IBD) involves interactions between the host genetic susceptibility, intestinal microflora and mucosal immune responses through the pattern recognition receptor. Polymorphisms in toll-like receptor 4 (TLR4) induce an aberrant immune response to indigenous intestinal flora, which might favor IBD development. In this study, we aimed to determine whether TLR4 gene was associated with Crohn’s disease (CD) and ulcerative colitis (UC) among Moroccan patients, and evaluated its correlation with clinical manifestation of the disease.

Methods

The study population comprised 117 patients with IBD and 112 healthy unrelated blood donors. TLR4 polymorphisms: Asp299Gly and Thr399Ile were genotyped by polymerase chain reaction-restriction fragment length polymorphism. PCR products were cleaved with Nco I for the Asp299Gly polymorphism and Hinf I for the Thr399Ile polymorphism. Meta-analysis was performed to test the association of 299Gly and 399Ileu carriage with CD, UC and the overall IBD risk.

Results

Our study revealed that the frequency of Asp299Gly and Thr399Ile did not differ significantly between patients and controls in the Moroccan population. However, meta-analysis demonstrated significantly higher frequencies of both Asp299Gly and Thr399Ile SNPs in IBD and CD and for 399Ileu carriage in UC patients.

Conclusion

The meta-analysis provides evidence that TLR4 polymorphisms confer a significant increased risk for the overall IBD development.

Infliximab therapy in pediatric patients 7 years of age and younger

BACKGROUND

Infliximab (IFX) is efficacious for induction and maintenance of remission in pediatric patients with moderate-to-severe inflammatory bowel disease (IBD). It has, however, not been studied in patients 7 years old and younger. Our aim was to characterize efficacy and safety of IFX therapy in this cohort.

METHODS

This was a retrospective study of patients with IBD ages 7 years and younger, treated with IFX between 1999 and 2011. Medical records were reviewed for age of diagnosis, disease phenotype, therapy, surgery, IFX infusion dates, dose, and intervals. Outcome measures included physician global assessment, corticosteroid requirement, and adverse events.

RESULTS

Thirty-three children (ages 2.4-7 years) were included. Twenty patients had Crohn disease, 4 had ulcerative colitis, and 9 had indeterminate colitis. Maintenance of IFX therapy at 1, 2, and 3 years was 36%, 18%, and 12%, respectively. Patients of age 5 years and younger had the lowest rates of maintenance of therapy at 25% at year 1, and 10% at years 2 and 3 combined. Nine percent of all of the patients demonstrated response measured by the physician global assessment and were steroid free at 1 year. There were 8 infusion reactions. There were no malignancies, serious infections, or deaths.

CONCLUSIONS

IFX demonstrated a modest response rate and a low steroid-sparing effect in patients with IBD 7 years old and younger. Although this is a limited study, there appears to be a trend for decreased sustained efficacy with IFX in this age group, particularly in children 5 years old and younger, when compared with the previously published literature in older children.

Role of genetics in pediatric inflammatory bowel disease

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD), ulcerative colitis (UC), and unclassified IBD, is characterized by chronic intestinal inflammation and has a multifactorial etiology with complex interactions between genetic and environmental factors. The genetics of IBD are believed to be common and complex with over 163 associated genetic loci. However, the genetic contribution of the majority of these common loci is small, and the effect sizes are low. Although childhood onset IBD represents only 10% to 25% of all IBD cases, in depth research into the genetic networks of pediatric IBD has revealed exciting new developments and unsuspected pathways. Recent pediatric studies have revealed an increasing spectrum of human monogenic diseases with high effect sizes or penetrance that can present with IBD or IBD-like intestinal inflammation. A substantial proportion of patients with these genetic defects present with very early onset of intestinal inflammation, with onset of IBD at less than 10 years of age. There is also considerable overlap with primary immunodeficiencies and very early onset IBD. This review summarizes the current understanding of the genetics of pediatric IBD with a focus on the very early onset population and discusses the promising results from the effort of finding missing heritability of IBD from studying pediatric population.

Genetic susceptibility and genotype-phenotype association in 588 Danish children with inflammatory bowel disease

AIM

To investigate the association between known inflammatory bowel disease (IBD)-associated genetic variants and development of paediatric IBD, and specific clinical sub-phenotypes.

MATERIAL AND METHODS

In this case-control study we included IBD patients <18 years of age at diagnosis from the Danish National Patient Registry and healthy children <18 years of age were randomly selected from the Danish Central Office of Civil Registration. The latter had filled out a questionnaire regarding health status, and DNA was obtained from blood samples and the buccal mucosa. Patient files were retrieved and clinical information was extracted. DNA was obtained from Guthrie cards from the Danish National Neonatal Screening Biobank (PKU-biobanken) at Statens Serum Institut and from blood samples.

RESULTS

A total of 588 IBD patients (244 Crohn's disease (CD), 318 ulcerative colitis (UC) and 26 IBD-unclassified (IBDU)) and 543 healthy controls were included. We found an association between CD and rs22411880 (ATG16L1, odds ratio (OR)=1.7 [1.1-1.7], p=0.003), rs5743289 (NOD2, OR=1.4 [1.1-1.9], p=0.009) and the paediatric specific rs1250550 (ZMIZ1, OR=0.7 [0.5-0.9], p=0.01). None of the investigated 41 SNPs were associated with disease localisation, medical treatment or surgery after correcting for multiple analyses.

CONCLUSION

We found an association between CD and three previously published genetic variants and replicated the association with the paediatric specific ZMIZ1 gene. No Bonferroni corrected significant genotype-phenotype associations were found. For future studies aimed at finding predictors for disease course in (paediatric) IBD, it will be worthwhile to include a combination of genetic, clinical and serological markers.

Autophagy genes variants and paediatric Crohn's disease phenotype: a single-centre experience

BACKGROUND AND AIMS

Little evidence demonstrating the correlation between several single nucleotide polymorphisms and a specific phenotype of Crohn's disease has been reported in children. We investigated the relationship between autophagy genes variants and clinical features in our children with Crohn's disease.

METHODS

Genotyping for ATG16L1, NOD2/CARD15, and IRGM1 was performed in 80 consecutive patients with Crohn's disease (median age: 11 years; range: 0.7-17.9 years). Crohn's disease location and behaviour were classified using the Paris classification. Additional data were collected from clinical records on patients' demographics, age at symptom onset and diagnosis, extraintestinal manifestations, therapy, clinical relapses, and need of surgical intervention.

RESULTS

Patients homozygous for the risk allele ATG16L1 (T300A) showed a trend towards switching to a stricturing phenotype during the course of disease compared to children either homozygous for the wild-type allele or heterozygous for the ATG16L1 single nucleotide polymorphism (p=0.01). Homozygosity for the ATG16L1 risk allele was associated with a major recurrence of clinical relapses and earlier introduction of immunosuppressants (p=0.006 and p=0.04, respectively). Heterozygosity for the NOD2 rs2066847 allele was associated with major ileal involvement (p=0.01).

CONCLUSION

In patients carrying the T300A variant, Crohn's disease follows a more aggressive clinical course.

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.

Phenotype and disease course of early-onset pediatric inflammatory bowel disease

BACKGROUND

Early-onset (EO) pediatric inflammatory bowel diseases (IBD) seem to be more extensive than those with a later onset. To test this hypothesis, we examined the phenotype and disease course of patients with IBD diagnosis at 0 to 5 years, compared with the ranges 6 to 11 and 12 to 18 years.

METHODS

Anatomic locations and behaviors were assessed according to Paris classification in 506 consecutive patients: 224 Crohn's disease, 245 ulcerative colitis, and 37 IBD-unclassified.

RESULTS

Eleven percent of patients were in the range 0 to 5 years, 39% in 6 to 11 years, and 50% in 12 to 18 years. Ulcerative colitis was the most frequent diagnosis in EO-IBD and in 6- to 11-year-old group, whereas Crohn's disease was predominant in older children. A classification as IBD-unclassified was more common in the range 0 to 5 years compared with the other groups (P < 0.005). EO Crohn's disease showed a more frequent isolated colonic (P < 0.005) and upper gastrointestinal involvement than later-onset disease. Sixty-two percent of the patients in the 0 to 5 years range had pancolonic ulcerative colitis, compared with 38% of 6 to 11 years (P = 0.02) and 31% of 12-18 years (P = 0.002) range. No statistical difference for family history for IBD was found in the 3-year age groups. Therapies at the diagnosis were similar for all children. However, at latest follow-up, a significantly higher proportion of younger children were under steroids compared with older groups (P < 0.05). Surgical risk did not differ according to age.

CONCLUSIONS

EO-IBD exhibits an extensive phenotype and benefit from aggressive treatment strategies, although surgical risk is similar to later-onset disease. A family history for IBD is not common in EO disease.

Systematic review with meta-analysis: inflammatory bowel disease in the elderly

BACKGROUND

Elderly patients represent an increasing proportion of the inflammatory bowel disease (IBD) population.

AIM

To critically review available data regarding the care of elderly IBD patients.

METHODS

Bibliographic searches (MEDLINE) up to June 2013.

RESULTS

Approximately 10-15% of cases of IBD are diagnosed in patients aged >60 years, and 10-30% of the IBD population are aged >60 years. In the elderly, IBD is easily confused with other more common diseases, mainly diverticular disease and ischaemic colitis. The clinical features of IBD in older patients are generally similar to those in younger patients. Crohn's disease (CD) in elderly patients is characterised by its predominantly colonic localisation and uncomplicated course. Proctitis and left-sided ulcerative colitis are more common in patients aged >60 years. Infections are associated with age and account for significant mortality in IBD patients. The treatment of IBD in the elderly is generally similar. However, the therapeutic approach in the elderly should be 'start low-go slow'. The benefit of thiopurines in older CD patients remains debatable. Although the indications for anti-tumour necrosis factors in the elderly are generally similar to those for younger patients, lower response and higher adverse events have been reported in the elderly. Surgery in elderly patients does not generally differ. Ileal pouch-anal anastomosis can be successful, provided the patient retains good anal sphincter function.

CONCLUSIONS

Management of the older IBD patient differs from that of younger patients; therefore, conventional practice algorithms may have to be modified to account for advanced age.

IBD across the age spectrum: is it the same disease?

IBD is a chronic disorder with disease onset ranging from early childhood to beyond the sixth decade of life. The factors that determine the age of onset currently remain unexplained. Is timing of occurrence a random event or is it indicative of different pathophysiological pathways leading to different phenotypes across the age spectrum? Over the past decade, several studies have suggested that the characteristics and natural history of IBD seem to be different according to age of onset. This heterogeneity suggests that the respective contributions of genetics, host immune system and environment to the aetiology and phenotype of Crohn's disease and ulcerative colitis are different across ages. Critical reviews that focus on differences characterizing IBD between age groups are scarce. Therefore, this Review updates the knowledge of the differences in epidemiology, clinical characteristics, and natural history of paediatric, adult and elderly-onset IBD. In addition, potential differences in host-gene-microbial interactions according to age are highlighted.

How does genotype influence disease phenotype in inflammatory bowel disease?

Inflammatory bowel diseases (Crohn's disease and ulcerative colitis) are chronic immunologically mediated diseases of the gut. Advances in genetics have revolutionized our understanding of the pathogenesis of these conditions with 163 risk loci identified, encompassing a variety of immunologic functions. There is substantial heterogeneity in the natural history of these diseases with respect to disease onset, course, and progression to complications. There are also significant variations in response to therapies and susceptibility to therapy-related and disease-related complications. An important need in the field is to identify predictors of disease course, complications, and likelihood of response and adverse events to allow for targeted therapeutic decision making. The genotype of an individual in constant and non-modifiable, and thus could potentially fulfill the role of important predictors of these outcomes. In this review, we discuss the existing literature on the prediction of various disease phenotypes in Crohn's disease and ulcerative colitis using underlying genotype. We also identify gaps in the literature and suggest future directions for research. There is need for large, multi-institutional, and international collaborative consortia with efficient and detailed cohort accrual, phenotypic definition, genotyping, and dynamic assessments of external (e.g., diet) and internal (microbiome) environment to allow us to progress toward personalized and precision medicine in the management of these complex diseases.