Polymorphisms of tumor necrosis factor-alpha but not MDR1 influence response to medical therapy in pediatric-onset inflammatory bowel disease

Glucocorticoids, their uses, sexual dimorphisms, and diseases: new concepts, mechanisms, and discoveries

The normal stress response in humans is governed by the hypothalamic-pituitary-adrenal (HPA) axis through heightened mechanisms during stress, raising blood levels of the glucocorticoid hormone cortisol. Glucocorticoids are quintessential compounds that balance the proper functioning of numerous systems in the mammalian body. They are also generated synthetically and are the preeminent therapy for inflammatory diseases. They act by binding to the nuclear receptor transcription factor glucocorticoid receptor (GR), which has two main isoforms (GRα and GRβ). Our classical understanding of glucocorticoid signaling is from the GRα isoform, which binds the hormone, whereas GRβ has no known ligands. With glucocorticoids being involved in many physiological and cellular processes, even small disruptions in their release via the HPA axis, or changes in GR isoform expression, can have dire ramifications on health. Long-term chronic glucocorticoid therapy can lead to a glucocorticoid-resistant state, and we deliberate how this impacts disease treatment. Chronic glucocorticoid treatment can lead to noticeable side effects such as weight gain, adiposity, diabetes, and others that we discuss in detail. There are sexually dimorphic responses to glucocorticoids, and women tend to have a more hyperresponsive HPA axis than men. This review summarizes our understanding of glucocorticoids and critically analyzes the GR isoforms and their beneficial and deleterious mechanisms and the sexual differences that cause a dichotomy in responses. We also discuss the future of glucocorticoid therapy and propose a new concept of dual GR isoform agonist and postulate why activating both isoforms may prevent glucocorticoid resistance.

Long-term Disease Course of Crohn's Disease: Changes in Disease Location, Phenotype, Activities, and Predictive Factors

Crohn's disease (CD) is a chronic destructive inflammatory bowel disease that affects young people and is associated with significant morbidity. The clinical spectrum and disease course of CD are heterogeneous and often difficult to predict based on the initial presentation. In this article, changes in the disease location, behavior, clinical course during long-term follow-up, and predictive factors are reviewed. Generally, four different patterns of clinical course are discussed: remission, stable disease, chronic relapsing disease, and chronic refractory disease. Understanding the long-term disease course of CD is mandatory to reveal the underlying pathophysiology of the disease and to move toward a more optimistic disease course, such as remission or stability, and less adverse outcomes or devastating sequelae.

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.

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

BACKGROUND & AIMS

A better understanding of prognostic factors in ulcerative colitis (UC) could improve patient management and reduce complications. We aimed to identify evidence-based predictors for outcomes in pediatric UC, which may be used to optimize treatment algorithms.

METHODS

Potential outcomes worthy of prediction in UC were determined by surveying 202 experts in pediatric UC. A systematic review of the literature, with selected meta-analysis, was performed to identify studies that investigated predictors for these outcomes. Multiple national and international meetings were held to reach consensus on evidence-based statements.

RESULTS

Consensus was reached on 31 statements regarding predictors of colectomy, acute severe colitis (ASC), chronically active pediatric UC, cancer and mortality. At diagnosis, disease extent (6 studies, N = 627; P = .035), Pediatric Ulcerative Colitis Activity Index score (4 studies, n = 318; P < .001), hemoglobin, hematocrit, and albumin may predict colectomy. In addition, family history of UC (2 studies, n = 557; P = .0004), extraintestinal manifestations (4 studies, n = 526; P = .048), and disease extension over time may predict colectomy, whereas primary sclerosing cholangitis (PSC) may be protective. Acute severe colitis may be predicted by disease severity at onset and hypoalbuminemia. Higher Pediatric Ulcerative Colitis Activity Index score and C-reactive protein on days 3 and 5 of hospital admission predict failure of intravenous steroids. Risk factors for malignancy included concomitant diagnosis of primary sclerosing cholangitis, longstanding colitis (>10 years), male sex, and younger age at diagnosis.

CONCLUSIONS

These evidence-based consensus statements offer predictions to be considered for a personalized medicine approach in treating pediatric UC.

NGS study of glucocorticoid response genes in inflammatory bowel disease patients

INTRODUCTION

Despite intensive research and a long history of glucocorticoids being applied in various clinical areas, they still generate a challenge for personalized medicine by causing resistance or dependence in nearly 50% of patients treated. The objective of the present study was to determine the genetic predictors of variable reactions in inflammatory bowel disease patients to glucocorticoid therapy. Therefore, based on the current knowledge on how glucocorticoids act, we have compiled a panel of 21 genes for variant analysis: NR3C1, NLRP1, IPO13, FKBP5, HSPA4, ABCB1, STIP1, HSP90AA1, IL-1A, IL-1B, IL-2, IL-4, CXCL8, IL-10, NFKBIA, JUN, MIF, TNF, MAPK14, CYP3A4, and CYP3A5.

MATERIAL AND METHODS

These genes were analyzed using the amplicon next-generation sequencing method in a group of 139 diagnosed and clinically characterized inflammatory bowel disease patients with a confirmed glucocorticoid response.

RESULTS

Analysis of all the targeted DNA sequences for the whole patient group indicated 121 different functional variants. After association analyses of 31 selected variants, the polymorphism c.1088A>G in the NR3C1 gene was linked with glucocorticoid resistance (p = 0.002), variant c.241+6A>G of the FKBP5 gene with glucocorticoid sensitivity (p = 0.040), and deletion c.306-7delT in the MAPK14 gene with an adverse therapeutic effect (dependency and resistance, p = 0.041) in ulcerative colitis patients. In Crohn's disease, the change c.2685+49T>C of the ABCB1 gene related to glucocorticoid resistance (p = 0.034).

CONCLUSIONS

Among the 21 analyzed genes, four (NR3C1, FKBP5, MAPK14, and ABCB1) revealed a significant impact on the glucocorticoid treatment response, which could result in valuable pharmacogenetic biomarkers after being confirmed in other populations and in functional studies.

Pharmacogenetics of treatments for inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease is a chronic inflammation of the gut whose pathogenesis is still unclear. Although no curative therapy is currently available, a number of drugs are used in induction and maintenance therapy; however, for most of these drugs, a high inter-individual variability in response is observed. Among the factors of this variability, genetics plays an important role. Areas covered: This review summarizes the results of pharmacogenetic studies, considering the most important drugs used and in particular aminosalycilates, glucocorticoids, thiopurines, monoclonal antibodies and thalidomide. Most studies used a candidate gene approach, even if significant breakthroughs have been obtained recently from applying genome-wide studies. When available, also investigations considering epigenetics and pharmacogenetic dosing guidelines have been included. Expert opinion: Only for thiopurines, genetic markers identified as predictors of efficacy or adverse events have allowed the development of dosing guidelines. For the other drugs, encouraging results are available and great expectations rely on the study of epigenetics and integration with pharmacokinetic information, especially useful for biologics. However, to improve therapy of IBD patients with these drugs, for implementation in the clinics of pharmacogenetics, informatic clinical decision support systems and training about pharmacogenetics of health providers are needed.

Pharmacogenetics of inflammatory bowel disease: a focus on Crohn's disease

Crohn's disease is an inflammatory bowel disease showing a high heterogeneity in phenotype and a strong genetic component. The treatment is complex, due to different severity of clinical parameters and to the fact that therapies only permit to control symptoms and to induce remission for short periods. Moreover, all categories of drugs present a great interindividual variability both in terms of efficacy and side effects appearance. For this reason, the identification of specific genomic biomarkers involved in drugs response will be of great clinical utility in order to foresee drug's efficacy and to prevent adverse reactions, permitting a more personalized therapeutic approach. In this review, we focus the attention on the pharmacogenetic studies regarding drugs commonly utilized in Crohn's disease treatment.

Genetic variation in the glucocorticoid pathway involved in interindividual differences in the glucocorticoid treatment

Glucocorticoids (GCs) are widely used for treating asthma, rheumatoid arthritis, nephrotic syndrome, acute lymphoblastic leukemia and other autoimmune diseases. However, in a subgroup of patients, failure to respond to GCs is known as GC resistance or GC insensitivity. This represents an important barrier to effective treatment and a clinical problem requiring an urgent solution. Genetic variation in the GC pathway is a significant factor in interindividual differences in GC treatment. This article reviews the pharmacogenetics of GCs in diverse diseases based on the GC pathway.

Association between MDR1 gene polymorphisms and the risk of Crohn's disease in a cohort of Algerian pediatric patients

BACKGROUND

The multi-drug resistance gene (MDR1) has raised increasing interest as a susceptibility gene for Crohn's disease (CD). The role of MDR1 single-nucleotide polymorphisms (SNPs) in the predisposition and behavior of CD in the pediatric population is still elusive. Here, we investigated whether SNPs in MDR1 are associated with CD in Algerian pediatric patients.

METHODS

A case-control study was conducted enrolling 47 pediatric CD patients and 100 controls. All subjects were genotyped for the most common MDR1 SNPs (C3434T, C1236T, and G2677A/T) using PCR-RFLP method. We also explored the association between polymorphisms and clinical sub-phenotypes.

RESULTS

We have detected no significant association of C3435T SNP and pediatric CD. However, we observed a significantly higher frequency of the risk alleles, 1236T and 2677T/A among the CD patients compared to controls. Moreover, the risk allele 1236T was associated to a higher risk for resective surgery.

CONCLUSION

Our data suggest that the C1236T and G2677A/T SNPs in the MDR1 gene are associated with CD and the C1236T risk allele with a more severe course of disease in Algerian pediatric patients. Further analysis using larger patients group and functional studies would be interesting to elucidate the role of MDR1 gene in pediatric CD.Pediatric Research (2016); doi:10.1038/pr.2016.163.

Association of tumor necrosis factor-α and -β gene polymorphisms in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a complex, multifactorial, chronic inflammatory disorder of the gastrointestinal tract in which immune dysregulation caused by genetic and/or environmental factors plays an important role. The aim of this case–control study was to evaluate the association of tumor necrosis factor-alpha (TNF-α) (308) and -β (+252) polymorphisms with susceptibility of IBD. A total of 379 Saudi subjects including 179 IBD patients (ulcerative colitis (UC) =84 and Crohn’s disease (CD) =95) and 200 age- and sex-matched healthy controls were recruited. TNF-α and TNF-β genes were amplified using an amplification refractory mutation systems polymerase chain reaction methodology to detect TNF-α (−308) and -β (+252) polymorphisms. The frequency of the GA genotype of TNF-α (−308G/A) was higher, and the frequencies of the GG and AA genotypes were significantly lower in IBD patients compared with those in controls, indicating that genotype GA-positive individuals are susceptible to IBD and that the GG and AA genotypes exert a protective effect. The frequency of allele A of TNF-α (−308G/A) was significantly higher and that of allele G was lower in IBD patients compared with those in controls, indicating an association of allele A with IBD risk in Saudi patients. On stratification of IBD patients into UC and CD, an almost similar pattern was noticed in both the groups. The results of TNF-β (+252A/G) polymorphisms showed a significant increase in the frequency of the GG genotype in IBD patients, suggesting a positive association of GG genotype with IBD risk. On stratification of IBD patients into UC and CD, the genotype GG of TNF-β was associated with susceptibility risk to UC but not CD. The frequencies of alleles and genotypes of both TNF-α and-β polymorphisms are not affected by sex or type of IBD (familial or sporadic). TNF-α (−308G/A) and TNF-β (+252A/G) polymorphisms are associated with risk of developing IBD in Saudi population.

The impact of genetic factors on response to glucocorticoids therapy in IBD

Glucocorticosteroids (GCs) are used for many years as first-line drugs for the achievement of remission in exacerbations of inflammatory bowel disease (IBD). However, close to 20% of patients are resistant to GCs, and 40% of patients become dependent on GCs. The challenge of today's personalized medicine is the anticipation of the steroid therapy effects even before the initiation of treatment. As several studies show, individually variable response to GCs in population has a genetic background and may depend on gene variability encoding proteins involved in the function and metabolism of GCs. To those genes belong: NR3C1--responsible for the synthesis of GC receptor (GR); Hsp90, HSP70, STIP1, FKB5--genes of GR protein complex; ABCB1 and IPO13 coding glycoprotein p170; and importin 13--involved in GCs transport; IL1A, IL1B, IL2, IL4, IL8, IL10, TNF, and MIF--genes of the epithelial pro-inflammatory factors synthesis, which excessive activation causes steroid resistance as well as CYP3A4 and CYP3A5--encoding GCs biotransformation enzymes. This work systematizes and sums up the state of current knowledge in the field of pharmacogenetics as well as expectations for the future in the realm of individualized medicine in IBD patients treated with GC drugs.

Characteristics of Pediatric Crohn's Disease in Saudi Children: A Multicenter National Study

Background and Aims. Crohn's disease (CD) is an evolving disease in KSA. Little is known about its characteristics in the Saudi population. The aims of this study were to describe the characteristics of Saudi children with CD and to determine whether the characteristics of CD in KSA are different from those seen in Western countries. Methods. In this study, children younger than eighteen years of age diagnosed with CD between January 2003 and December 2012 were included. Results. Of 330 patients identified, 186 (56.4%) were males. The median age at diagnosis was 15.8 years. A positive family history for IBD in first-degree relatives occurred in 13.6% of patients. The most common symptoms were abdominal pain (84.2%), weight loss (75.2%), and diarrhea (71.8%). The main disease location was ileocolonic (42.1%) and the main disease behavior was nonstricturing and nonpenetrating (63.6%). Perianal involvement was seen in 60 (18.2%) patients. Laboratory findings revealed anemia in 57.9% of patients, low albumin in 34.5%, and high CRP in 39.4%. Conclusions. Saudi children with CD have lower frequency of first-degree relatives with IBD, lower prevalence of early onset disease, longer diagnostic delay, higher prevalence of growth failure, and greater frequency of stricturing and penetrating disease behavior compared to Western patients.

Update on pathogenesis and predictors of response of therapeutic strategies used in inflammatory bowel disease

The search for biomarkers that characterize specific aspects of inflammatory bowel disease (IBD), has received substantial interest in the past years and is moving forward rapidly with the help of modern technologies. Nevertheless, there is a direct demand to identify adequate biomarkers for predicting and evaluating therapeutic response to different therapies. In this subset, pharmacogenetics deserves more attention as part of the endeavor to provide personalized medicine. The ultimate goal in this area is the adjustment of medication for a patient’s specific genetic background and thereby to improve drug efficacy and safety rates. The aim of the following review is to utilize the latest knowledge on immunopathogenesis of IBD and update the findings on the field of Immunology and Genetics, to evaluate the response to the different therapies. In the present article, more than 400 publications were reviewed but finally 287 included based on design, reproducibility (or expectancy to be reproducible and translationable into humans) or already measured in humans. A few tests have shown clinical applicability. Other, i.e., genetic associations for the different therapies in IBD have not yet shown consistent or robust results. In the close future it is anticipated that this, cellular and genetic material, as well as the determination of biomarkers will be implemented in an integrated molecular diagnostic and prognostic approach to manage IBD patients.

TNF-α SNP rs1800629 and risk of relapse in childhood acute lymphoblastic leukemia: relation to immunophenotype

AIM

In the AIEOP-BFM ALL (Associazione Italiana Ematologia Oncologia Pediatrica-Berlin Frankfurt Münster acute lymphoblastic leukemia) 2000 protocol, 70% of relapsed patients had favorable prognostic features and fell within less intensive polychemotherapeutic regimens, suggesting the need for better assessing lower risk stratification.

MATERIALS & METHODS

A novel two-phase study design selected 614 children to be genotyped for TNF-α SNP rs1800629 (-308G>A). A weighted Cox model was applied to evaluate the SNP effect on hazard of relapse, adjusting for immunophenotype, risk group, age and gender and including interaction terms.

RESULTS

Significant interaction was found with immunophenotypes (p = 0.0007, with minor allele genotypes being adverse genetic markers in B-cell acute lymphoblastic leukemia and protective ones in T-cell acute lymphoblastic leukemia), and also with risk protocols (p = 0.0041, with minor allele genotypes as prognostic factor of relapse for standard risk patients [only one T-cell acute lymphoblastic leukemia in the subgroup analyzed]).

CONCLUSION

The presence of at least one A allele in TNF-α SNP rs1800629 should suggest a closer monitoring in B-cell acute lymphoblastic leukemia standard risk patients.

Genetic update on inflammatory factors in ulcerative colitis: Review of the current literature

Ulcerative colitis (UC) is one of the main types of inflammatory bowel disease, which is caused by dysregulated immune responses in genetically predisposed individuals. Several genetic factors, including interleukin and interleukin receptor gene polymorphisms and other inflammation-related genes play central role in mediating and modulating the inflammation in the human body, thereby these can be the main cause of development of the disease. It is clear these data are very important for understanding the base of the disease, especially in terms of clinical utility and validity, but summarized literature is exiguous for challenge health specialist that can used in the clinical practice nowadays. This review summarizes the current literature on inflammation-related genetic polymorphisms which are associated with UC. We performed an electronic search of Pubmed Database among publications of the last 10 years, using the following medical subject heading terms: UC, ulcerative colitis, inflammation, genes, polymorphisms, and susceptibility.

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.

P-glycoprotein and drug resistance in systemic autoimmune diseases

Autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are chronic inflammatory disorders of unknown etiology characterized by a wide range of abnormalities of the immune system that may compromise the function of several organs, such as kidney, heart, joints, brain and skin. Corticosteroids (CCS), synthetic and biologic immunosuppressive agents have demonstrated the capacity to improve the course of autoimmune diseases. However, a significant number of patients do not respond or develop resistance to these therapies over time. P-glycoprotein (P-gp) is a transmembrane protein that pumps several drugs out of the cell, including CCS and immunosuppressants; thus, its over-expression or hyper-function has been proposed as a possible mechanism of drug resistance in patients with autoimmune disorders. Recently, different authors have demonstrated that P-gp inhibitors, such as cyclosporine A (CsA) and its analogue Tacrolimus, are able to reduce P-gp expression and or function in SLE, RA and PsA patients. These observations suggest that P-gp antagonists could be adopted to revert drug resistance and improve disease outcome. The complex inter-relationship among drug resistance, P-gp expression and autoimmunity still remains elusive.

Clinical and genetic factors predicting response to therapy in patients with Crohn's disease

AIM

To identify clinical and/or genetic predictors of response to several therapies in Crohn's disease (CD) patients.

METHODS

We included 242 patients with CD (133 females) aged (mean ± standard deviation) 39 ± 12 years and a disease duration of 12 ± 8 years. The single-nucleotide polymorphisms (SNPs) studied were ABCB1 C3435T and G2677T/A, IL23R G1142A, C2370A, and G9T, CASP9 C93T, Fas G670A and LgC844T, and ATG16L1 A898G. Genotyping was performed with real-time PCR with Taqman probes.

RESULTS

Older patients responded better to 5-aminosalicylic acid (5-ASA) and to azathioprine (OR 1.07, p = 0.003 and OR 1.03, p = 0.01, respectively) while younger ones responded better to biologicals (OR 0.95, p = 0.06). Previous surgery negatively influenced response to 5-ASA compounds (OR 0.25, p = 0.05), but favoured response to azathioprine (OR 2.1, p = 0.04). In respect to genetic predictors, we observed that heterozygotes for ATGL16L1 SNP had a significantly higher chance of responding to corticosteroids (OR 2.51, p = 0.04), while homozygotes for Casp9 C93T SNP had a lower chance of responding both to corticosteroids and to azathioprine (OR 0.23, p = 0.03 and OR 0.08, p = 0.02,). TT carriers of ABCB1 C3435T SNP had a higher chance of responding to azathioprine (OR 2.38, p = 0.01), while carriers of ABCB1 G2677T/A SNP, as well as responding better to azathioprine (OR 1.89, p = 0.07), had a lower chance of responding to biologicals (OR 0.31, p = 0.07), which became significant after adjusting for gender (OR 0.75, p = 0.005).

CONCLUSIONS

In the present study, we were able to identify a number of clinical and genetic predictors of response to several therapies which may become of potential utility in clinical practice. These are preliminary results that need to be replicated in future pharmacogenomic studies.

Dominance of the strongest: inflammatory cytokines versus glucocorticoids

Pro-inflammatory cytokines are involved in the pathogenesis of many inflammatory diseases, and the excessive expression of many of them is normally counteracted by glucocorticoids (GCs), which are steroids that bind to the glucocorticoid receptor (GR). Hence, GCs are potent inhibitors of inflammation, and they are widely used to treat inflammatory diseases, such as asthma, rheumatoid arthritis and inflammatory bowel disease. However, despite the success of GC therapy, many patients show some degree of GC unresponsiveness, called GC resistance (GCR). This is a serious problem because it limits the full therapeutic exploitation of the anti-inflammatory power of GCs. Patients with reduced GC responses often have higher cytokine levels, and there is a complex interplay between GCs and cytokines: GCs downregulate pro-inflammatory cytokines while cytokines limit GC action. Treatment of inflammatory diseases with GCs is successful when GCs dominate. But when cytokines overrule the anti-inflammatory actions of GCs, patients become GC insensitive. New insights into the molecular mechanisms of GR-mediated actions and GCR are needed for the design of more effective GC-based therapies.

Genetic variants of membrane metallopeptidase genes in inflammatory bowel diseases

BACKGROUND

The substance P pathway modulates neuroimmune interactions during intestinal inflammation.

AIMS

To analyse mucosal expression and genetic variants of the genes coding for substance P, neurokinin-1 receptor and neutral endopeptidase in patients with inflammatory bowel disease.

METHODS

qRT-PCR was used to analyse mRNA levels in matched, paired samples of inflamed colonic mucosa and adjacent non-inflamed endoscopic tissue from 26 Crohn's disease and 25 ulcerative colitis patients. Allele and genotype frequencies of tag-SNPs were determined in 908 Crohn's disease, 929 ulcerative colitis, and 853 controls. Expression levels and genotype distributions were examined within patients' clinical sub-phenotypes.

RESULTS

All 3 evaluated genes were overexpressed in inflamed tissues from Crohn's disease (P=0.033, P=4×10(-5), P=0.001), while in ulcerative colitis only higher levels of the gene coding for neutral endopeptidase were statistically significant (P=2.5×10(-5)). Smoking habit and perianal disease were significantly associated with substance P (P=0.002) and neurokinin-1 receptor levels (P=0.02) in Crohn's disease. Neutral endopeptidase rs701109 variant was associated with inflammatory bowel disease (Crohn's disease: P=0.022; ulcerative colitis: P=0.045), and with the need for colectomy in ulcerative colitis (P=0.008, OR=2.46, 95% CI=1.27-4.76).

CONCLUSIONS

Genetic variants of the gene coding for neutral endopeptidase might affect the neuroimmune interaction during intestinal inflammation and influence clinical sub-phenotypes in patients with inflammatory bowel disease.

Genetic variants associated with Crohn's disease

Crohn’s disease is an immune-related disorder characterized by inflammation of the gastrointestinal mucosa, which can occur in any area throughout the digestive tract. This life-long disease commonly presents with abdominal pain, diarrhea, vomiting, and weight loss. While the exact etiology of this disease is largely unknown, it is thought to arise from an interaction between microbial, immunological, and environmental factors in a genetically susceptible host, whereby the immune system attacks the intestine as it cross reacts against gut microbial antigens. The study of genetic variants associated with Crohn’s disease has shed light on our understanding of disease pathophysiology. A large number of genetic variants identified in Crohn’s disease are related to genes targeting microbial recognition and bacterial wall sensing, the most common being NOD2/CARD15 gene. This review will discuss the recent advance in our knowledge of genetic variants of this disease and how they influence the disease course and prognosis.

Associations between genetic polymorphisms in IL-33, IL1R1 and risk for inflammatory bowel disease

BACKGROUND

Recent evidence suggests that the IL-33/IL1RL1 axis plays a critical role in several autoimmune and inflammatory disorders; however, its mechanistic role in inflammatory bowel disease (IBD) has not been clearly defined. We investigated the contribution of IL-33 and IL1RL1 polymorphisms to IBD risk, and possible correlations with phenotype in an Italian cohort of adult and pediatric patients.

METHODS

We evaluated the association of six SNPs in IL-33 and IL1RL1 genes, in 805 Crohn's disease (CD), 816 ulcerative colitis (UC), and 752 controls, using Taqman. IL-33 and IL1RL1 mRNA expression was also analyzed.

RESULTS

Significant allele and genotype associations with IL-33 rs3939286 were found in CD (P = 0.004; P = 0.035) and UC patients (P = 0.002; P = 0.038). After stratifying the cohort for age at diagnosis, the differences remained significant only in the IBD adult-onset. Significant associations were also obtained in CD patients with two IL1RL1 polymorphisms (rs13015714 and rs2058660, P<0.015). By combining homo- and heterozygous carriers of the rs13015714 risk allele, differences were still significant for both CD adult- and pediatric-onset. Upon genotype-phenotype evaluation, an increased frequency of extensive colitis in adult UC (P = 0.019) and in steroid-responsive pediatric patients (P = 0.024) carrying the IL-33 rs3939286 risk genotype, was observed. mRNA expression of IL-33 and IL1RL1 in inflamed IBD biopsy samples was significantly increased.

CONCLUSIONS

Common IL-33 and IL1RL1 polymorphisms contribute to the risk of IBD in an Italian cohort of adult and pediatric patients, with some influence on sub-phenotypes.

Glucocorticoid sensitivity in inflammatory bowel disease

Glucocorticoid therapy is used in the treatment of moderate to severe inflammatory bowel disease (IBD). However, IBD patients display varying degrees of glucocorticoid sensitivity: some respond rapidly to the given treatment, whereas others show no response, or develop steroid therapy-related side-effects. At present, we cannot foresee whether the patient will benefit from the administered glucocorticoids or not. During the past 10 years, numerous attempts have been made to provide the means to identify and predict steroid therapy-sensitive patients in advance. This would be vital to avoid unnecessary glucocorticoid exposure in patients that do not respond to treatment with steroids. Here we provide a concise review of recent developments regarding the molecular basis of glucocorticoid sensitivity in IBD patients and the methods employed to assess it.

Differences in the location and activity of intestinal Crohn's disease lesions between adult and paediatric patients detected with MRI

OBJECTIVES

To prospectively compare paediatric patients (PP) and adult patients (AP) affected by Crohn's disease (CD) in terms of the location and activity of intestinal lesions.

METHODS

Forty-three children (mean age 15 years) and 43 adults (mean age 48 years) with proven CD underwent magnetic resonance enterography (MRE) to localise lesions and detect their activity in 9 segments of the small and large bowel. The results were analysed on a per patient and per segment basis. Ileo-colonoscopy was performed in all patients. P values less than 0.05 were considered statistically significant.

RESULTS

Involvement of terminal ileum was significantly different in the two groups: observed in 100 % of AP (43/43) versus 58 % (23/43) of PP (P < 0.0001). Conversely, the colon was diseased in 84 % of PP versus 64 % of AP. In particular, left colonic segments were significantly more involved in PP (descending colon 53 % versus 21 %, P < 0.01; rectum 67 % versus 23 %, P < 0.0001; sigmoid colon 56 % versus 37 %, not significant), whereas caecal involvement was equal in both groups. In children the maximal disease activity was found in left colonic segments, whereas in adults it was in the terminal ileum.

CONCLUSIONS

MRE detected significant differences between the two populations, showing a more extensive and severe involvement of the left colon in children but the distal ileum in adults.

KEY POINTS

• MRI is useful for assessing Crohn's disease in adult and paediatric patients. • Adult and paediatric patients show different intestinal involvement on MRI. • The distal ileum is maximally involved in adults vs. the left colon in children. • The causes of the severe left colonic disease in children are unknown. • The extensive colonic involvement in children has clinical-diagnostic implications.

Crucial steps in the natural history of inflammatory bowel disease

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

Clinical, serological and genetic predictors of inflammatory bowel disease course

Patients with extensive or complicated Crohn’s disease (CD) at diagnosis should be treated straightaway with immunosuppressive therapy according to the most recent guidelines. In patients with localized and uncomplicated CD at diagnosis, early use of immunosuppressive therapy is debated for preventing disease progression and limiting the disabling clinical impact. In this context, there is a need for predictors of benign or unfavourable subsequent clinical course, in order to avoid over-treating with risky drugs those patients who would have experienced spontaneous mid-term asymptomatic disease without progression towards irreversible intestinal lesions. At diagnosis, an age below 40 years, the presence of perianal lesions and the need for treating the first flare with steroids have been consistently associated with an unfavourable subsequent 5-year or 10-year clinical course. The positive predictive value of unfavourable course in patients with 2 or 3 predictors ranges between 0.75 and 0.95 in population-based and referral centre cohorts. Consequently, the use of these predictors can be integrated into the elements that influence individual decisions. In the CD postoperative context, keeping smoking and history of prior resection are the strongest predictors of disease symptomatic recurrence. However, these clinical predictors alone are not as reliable as severity of early postoperative endoscopic recurrence in clinical practice. In ulcerative colitis (UC), extensive colitis at diagnosis is associated with unfavourable clinical course in the first 5 to 10 years of the disease, and also with long-term colectomy and colorectal inflammation-associated colorectal cancer. In patients with extensive UC at diagnosis, a rapid step-up strategy aiming to achieve sustained deep remission should therefore be considered. At the moment, no reliable serological or genetic predictor of inflammatory bowel disease clinical course has been identified.

Genetics of inflammatory bowel disease in Asia: systematic review and meta-analysis

BACKGROUND

Inflammatory bowel diseases (IBD) result from an interaction between genetic and environmental factors. Preliminary findings suggest that susceptibility genes differ between IBD patients in Asia and the West. We aimed to evaluate disease-predisposing genes in Asian IBD patients.

METHODS

A systematic review and meta-analysis were performed of published studies from 1950 to 2010 using keyword searches in MEDLINE, EMBASE, EBM Reviews, and BIOSIS Previews.

RESULTS

In all, 477 abstracts were identified and data extracted from 93 studies, comprising 17,976 IBD patients and 27,350 age- and sex-matched controls. Major nucleotide oligomerization domain (NOD)-2 variants in Western Crohn's disease (CD) patients were not associated with CD in Han Chinese, Japanese, South Korean, Indian, and Malaysian populations. New NOD2 mutations were, however, associated with CD in Malaysians (JW1), Han Chinese, and Indians (P268S). Autophagy-related protein 16-linked 1 (ATG16L1) was not associated with CD in East Asians (odds ratio [OR] 0.97; 95% confidence interval [CI] 0.84-1.13). Interleukin (IL)-23R was associated with CD in South Koreans (OR 1.8; 95% CI 1.16-2.82) and a single nucleotide polymorphism in IL-23R (Gly149Arg) was protective of CD in Han Chinese (OR 0.3; 95% CI 0.15-0.60). Tumor necrosis factor (TNF) superfamily gene-15 (SF15) polymorphisms were associated with CD (OR 2.68; 95% CI 1.86-3.86), while TNF-308 polymorphisms (OR 1.82; 95% CI 1.15-2.9), cytotoxic T lymphocyte antigen (CTLA)-4 (OR 2.75; 95% CI 1.22-6.22) and MICA allele (OR 2.41; 95% CI 1.89-3.07) were associated with ulcerative colitis in Asians.

CONCLUSIONS

Genetic mutations of IBD in Asians differ from Caucasians. New mutations and susceptibility genes identified in Asian IBD patients provide an opportunity to explore new disease-associated mechanisms in this population of rising incidence.

NOD2 polymorphism predicts response to treatment in Crohn's disease--first steps to a personalized therapy

BACKGROUND AND AIMS

Great efforts have been made to predict disease behavior over time and the response to treatment in Crohn's disease (CD). Such understanding could personalize therapy. Early introduction of more aggressive therapies to patients at high risk and no introduction of predictable refractory treatments could become possible. We hence tested the influence of the NOD2 carrier status on treatment response.

PATIENTS AND METHODS

In 185 CD patients (age 45 ± 9.8 years, female n = 108, minimum disease duration 10 years), the three most common polymorphisms (p.Arg702Trp, p.Gly908Arg, p.Leu1007fsX1008) of NOD2 were tested by polymerase chain reaction and sequencing. Detailed clinical and medical history were obtained with a standardized questionnaire and by reviewing the medical charts. Treatments introduced were chosen by physicians blinded to genotype data.

RESULTS

The frequency of the NOD2 variant allele was about one-third (67, 30.2%) of CD patients. NOD2 carriers were more often treated with systemic and locally active steroids and with an immunosuppressant (Azathioprine/6-MP). NOD2 mutation carrier status was more often associated with systemic steroid [8.9% vs. wild-type (WT) 1.2%, P = 0.0086] and local-steroid refractory (14.9% vs. WT 3.5%; P = 0.001). The WT patients were significantly higher refractory to immunosuppressant (12.8% vs. NOD2 carriers, 0.5%, P = 0.03). Most WT patients were treated with TNF-α antagonists and remission rates were significantly higher in this group after 1 year of treatment (84% vs. NOD2 carriers, 33%, P = 0.07).

CONCLUSIONS

The study presents first hints for the NOD2 carrier status to be predictive for response to therapy. A higher percentage of CD patients with NOD2 mutation carrier status was steroid refractory but could be treated well with immunosuppressants. The WT status showed a higher response to steroids and remission rates within 1 year of anti-TNF-α therapy. On the way to personalized medicine, this approach should be further investigated in larger studies.

Genes associated with susceptibility to ulcerative colitis

Ulcerative colitis (UC) is a chronic intestinal inflammatory disease whose etiology is still unknown. It is widely believed that UC is a kind of non-specific inflammatory disease which is caused by environmental factors and autoimmune disorders in people who carry susceptibility genes. Epidemiologic data, such as familial aggregation, twin studies, and racial/ethnic differences in disease prevalence, indicate that there are genetic contributions to UC pathogenesis. In this article, we will review the recent progress in research of genes associated with susceptibility to UC.

Tumor necrosis factor inhibits glucocorticoid receptor function in mice: a strong signal toward lethal shock

As glucocorticoid resistance (GCR) and the concomitant burden pose a worldwide problem, there is an urgent need for a more effective glucocorticoid therapy, for which insights into the molecular mechanisms of GCR are essential. In this study, we addressed the hypothesis that TNFα, a strong pro-inflammatory mediator in numerous inflammatory diseases, compromises the protective function of the glucocorticoid receptor (GR) against TNFα-induced lethal inflammation. Indeed, protection of mice by dexamethasone against TNFα lethality was completely abolished when it was administered after TNFα stimulation, indicating compromised GR function upon TNFα challenge. TNFα-induced GCR was further demonstrated by impaired GR-dependent gene expression in the liver. Furthermore, TNFα down-regulates the levels of both GR mRNA and protein. However, this down-regulation seems to occur independently of GC production, as TNFα also resulted in down-regulation of GR levels in adrenalectomized mice. These findings suggest that the decreased amount of GR determines the GR response and outcome of TNFα-induced shock, as supported by our studies with GR heterozygous mice. We propose that by inducing GCR, TNFα inhibits a major brake on inflammation and thereby amplifies the pro-inflammatory response. Our findings might prove helpful in understanding GCR in inflammatory diseases in which TNFα is intimately involved.

The changing pattern of Crohn's disease incidence in northern France: a continuing increase in the 10- to 19-year-old age bracket (1988-2007)

BACKGROUND

Crohn's disease incidence rates have stabilised in industrialised countries since the 1980s. Conversely, a continuing increase in childhood-onset Crohn's disease incidence has been reported.

AIM

To confirm trends in inflammatory bowel disease (IBD) incidence in northern France over an extended time period (1988-2007) with a focus on childhood-onset Crohn's disease.

METHODS

The IBD patients recorded in the EPIMAD registry between 1988 and 2007 were included. Standardised incidence rates were calculated for Crohn's disease and ulcerative colitis in the entire population, and separately according to age. Evolution of phenotypes at diagnosis was also studied.

RESULTS

A total of 12 084 incident IBD cases (7428 Crohn's disease and 4656 ulcerative colitis) were recorded. Crohn's disease incidence rates increased from 5.2 cases/100 000 persons in 1988-1990 to 6.7 in 2006-2007 (+29%), stabilising after a peak at 7.1 in 1997-1999. Crohn's disease incidence rates in the 10-19-year age category increased by 71%, from 6.5 (1988-1990) to 11.1 (2006-2007). The frequency of initial ileo-colonic localisation increased from 52.9% in 1988-1990 to 68.6% in 2006-2007 (P<0.0001). Ulcerative colitis incidence rates decreased during the same period.

CONCLUSIONS

From 1988 to 2007, Crohn's disease incidence increased by 29% in northern France and by 71% in the 10-19-year-old age group. Consequently, studies on Crohn's disease risk factors should focus on the population under 20 years of age.

Molecular mechanism of glucocorticoid resistance in inflammatory bowel disease

Natural and synthetic glucocorticoids (GCs) are widely employed in a number of inflammatory, autoimmune and neoplastic diseases, and, despite the introduction of novel therapies, remain the first-line treatment for inducing remission in moderate to severe active Crohn’s disease and ulcerative colitis. Despite their extensive therapeutic use and the proven effectiveness, considerable clinical evidence of wide inter-individual differences in GC efficacy among patients has been reported, in particular when these agents are used in inflammatory diseases. In recent years, a detailed knowledge of the GC mechanism of action and of the genetic variants affecting GC activity at the molecular level has arisen from several studies. GCs interact with their cytoplasmic receptor, and are able to repress inflammatory gene expression through several distinct mechanisms. The glucocorticoid receptor (GR) is therefore crucial for the effects of these agents: mutations in the GR gene (NR3C1, nuclear receptor subfamily 3, group C, member 1) are the primary cause of a rare, inherited form of GC resistance; in addition, several polymorphisms of this gene have been described and associated with GC response and toxicity. However, the GR is not self-standing in the cell and the receptor-mediated functions are the result of a complex interplay of GR and many other cellular partners. The latter comprise several chaperonins of the large cooperative hetero-oligomeric complex that binds the hormone-free GR in the cytosol, and several factors involved in the transcriptional machinery and chromatin remodeling, that are critical for the hormonal control of target genes transcription in the nucleus. Furthermore, variants in the principal effectors of GCs (e.g. cytokines and their regulators) have also to be taken into account for a comprehensive evaluation of the variability in GC response. Polymorphisms in genes involved in the transport and/or metabolism of these hormones have also been suggested as other possible candidates of interest that could play a role in the observed inter-individual differences in efficacy and toxicity. The best-characterized example is the drug efflux pump P-glycoprotein, a membrane transporter that extrudes GCs from cells, thereby lowering their intracellular concentration. This protein is encoded by the ABCB1/MDR1 gene; this gene presents different known polymorphic sites that can influence its expression and function. This editorial reviews the current knowledge on this topic and underlines the role of genetics in predicting GC clinical response. The ambitious goal of pharmacogenomic studies is to adapt therapies to a patient’s specific genetic background, thus improving on efficacy and safety rates.

Relationship between the polymorphism of tumor necrosis factor-α-308 G>A and susceptibility to inflammatory bowel diseases and colorectal cancer: a meta-analysis

Inflammatory bowel disease (IBD) and colorectal cancer (CRC) are common health problems worldwide. Tumor necrosis factor (TNF) is a type of cytokine that induces inflammation and inhibits tumorigenesis. Several studies have assessed the relationship between the polymorphism of TNF-α-308 G>A and the susceptibility to IBD and CRC; however, the results have been controversial. In addition, the hypothesis whether the increased risk of CRC in IBD patients could be partly ascribed to the polymorphism of TNF-α-308 G>A was unclear. Therefore, we conducted this meta-analysis to confirm these associations. Pooled odd ratios (ORs) and 95% confidence intervals (95% CIs) were calculated on the basis of data from 14, 18, and 7 studies from a total of 27 studies for the associations between the polymorphism of TNF-α-308 G>A and ulcerative colitis, Crohn's disease (CD) and CRC. In Europeans, the AA genotype increased the risk of ulcerative colitis (UC) (OR, 2.041; 95% CI, 1.261-3.301) and CD (OR, 1.730; 95% CI, 1.168-2.564) significantly, without obvious heterogeneity and publication bias. Meanwhile, the GA genotype increased the risk of UC in Asians (OR, 2.360; 95% CI, 1.269-4.390) significantly. However, no significant association was observed for CRC in any ethnic population. The results of this meta-analysis suggested that the polymorphism of TNF-α-308 G>A participates in modifying the susceptibility to UC and CD in Europeans and Asians. The increased risk of CRC in IBD patients should be clarified as the combined effects of polymorphisms in TNF-α and other cytokines, and the interaction with environmental factors, in future studies.

TNFRSF1B A1466G genotype is predictive of clinical efficacy after treatment with a definitive 5-fluorouracil/cisplatin-based chemoradiotherapy in Japanese patients with esophageal squamous cell carcinoma

BACKGROUND

Currently definitive 5-fluorouracil (5-FU)/cisplatin (CDDP) -based chemotherapy is recognized as one of the most promising treatments for esophageal cancer. A series of studies performed found genetic polymorphisms and the plasma concentration of 5-FU to be predictive of acute severe toxicities and clinical response. Genetic polymorphisms of tumor necrosis factor (TNF) -alpha and its surface receptors, TNFRSF1A and TNFRSF1B have been examined in terms of susceptibility to various cancers. In this study, genetic polymorphisms of TNFRSF1B gene were evaluated Japanese esophageal squamous cell carcinoma (ESCC) patients treated with the definitive 5-FU/CDDP-based chemoradiotherapy and their predictive values of prognosis or severe acute toxicities were assessed.

METHODS

Forty-six patients with ESCC were treated with the definitive 5-FU/CDDP-based chemoradiotherapy, one course of which consisted of the continuous infusion of 5-FU for days 1-5 and 8-12, the infusion of CDDP on days 1 and 8, and the radiation at 2 Gy/day on days 1-5, 8-12, and 15-19, with a second course repeated after 2-week interval. Genetic polymorphisms of a TNF-alpha receptor TNFRSF1B gene were determined by a TaqMan(R) MGB probe-based polymerase chain reaction.

RESULTS

The genotype of TNFSR1B A1466G, but not M196R/T587G or C1493T, was found to be predictive of clinical response, i.e., a complete response or not (p = 0.040). Clinical response was predicted by tumor size (p = 0,002), lymph node metastasis (p = 0.007), distant metastasis (p = 0.001) and disease stage (p < 0.001), but TNFRSF1B A1466G genotype was independent of these factors.

CONCLUSIONS

Genetic polymorphism of TNFRSF1B A1466G was found to be predictive response in Japanese ESCC patients with a definitive 5-FU/CDDP-based chemoradiotherapy. Further clinical investigation with a large number of patients or experiments in vitro should be performed to assess the predictive value of TNFRSF1B A1466G genotype after chemoradiotherapy.

The -A2518G polymorphism of monocyte chemoattractant protein-1 is associated with Crohn's disease

OBJECTIVES

The -A2518G variation in monocyte chemoattractant protein (MCP)-1 gene promoter has been associated with autoimmune diseases. Our aim was to investigate the gene polymorphism and MCP-1 plasma levels in patients with inflammatory bowel disease (IBD).

METHODS

Family-based and case-control association analyses of the -A2518G polymorphism (rs1024611) were performed in 1,936 subjects (770 patients with Crohn's disease (CD), 316 patients with ulcerative colitis (UC), 302 healthy relatives (151 CD trios), and 548 healthy controls (HCs)). Extensive gene sequencing was also undertaken, and a further six single-nucleotide polymorphisms (SNPs) were genotyped in 435 CD patients and 189 HCs. MCP-1 protein plasma levels in 234 CD patients, 117 UC patients, and 108 HCs were assessed by an immunosorbent assay.

RESULTS

Five SNPs in strong linkage disequilibrium (D'>0.85) were associated with CD, with the strongest signal found at the -A2518G SNP. The frequency of the G allele was significantly lower in CD patients (22.1%), compared with HCs (29.8%), both at case-control (P=6 x 10(-6)) and at transmission disequilibrium test analyses (T/U 41/88; P=4 x 10(-4)). No difference in alleles (26.1%) and genotype frequencies were found in UC patients. MCP-1 plasma levels in CD and UC patients were similar to those in HCs (P=0.38), irrespective of disease activity, or MCP-1 genotypes. However, 30 CD (13%) and 20 UC patients (17%) with extensive colonic involvement had plasma levels significantly higher than HCs (P=0.02).

CONCLUSIONS

The -A2518G polymorphism seems to be associated with CD but does not influence MCP-1 plasma levels, which in contrast are increased in UC and CD with extensive colonic involvement.

Meta-analysis: polymorphisms in TNF-alpha gene promoter and Crohn's disease

BACKGROUND

Tumour necrosis factor alpha (TNF-alpha) is involved in the pathogenesis of Crohn's disease (CD). However, results on the association between the polymorphisms in TNF-alpha promoter and the risk of CD are inconsistent.

AIM

To perform a quantitative synthesis for the genetic polymorphisms in TNF-alpha promoter and CD risk.

METHODS

Databases were searched (up to 2009) and 31 studies were included. Risks of CD associated with the polymorphisms in TNF-alpha promoter were assessed.

RESULTS

Overall, individuals with -1031 TC+CC genotype had a slightly increased risk to develop CD compared with individuals with -1031 TT genotype (OR, 1.32; 95% CI, 1.03-1.70). In the further stratified analysis, we found Asians with the -1031T>C, -863 C>A and -857 C>T variant polymorphisms have almost one and a half CD risk compared with other genotypes (OR, 1.58; 95% CI, 1.16-2.15; OR, 1.55; 95% CI, 1.18-2.02; OR, 1.54; 95% CI, 1.19-1.99 respectively). We did not find -308 G>A variant associated with CD location and disease behaviours in stratified analysis.

CONCLUSIONS

TNF-alpha polymorphisms in the promoter region might be used as a biomarker for CD risk prediction. Larger studies with mixed ethnicity subjects and stratified by clinical and sub clinical characteristics are needed to validate our findings.

Variants at the 3p21 locus influence susceptibility and phenotype both in adults and early-onset patients with inflammatory bowel disease

BACKGROUND

To date, a number of high-profile studies have yielded over 50 inflammatory bowel disease (IBD) disease genes/loci. The polymorphisms rs9858542 (BSN) and rs3197999 (MST1), on 3p21 locus, have been found associated with susceptibility to IBD. We aimed to replicate these associations in adult and early-onset cohorts of IBD Italian patients, by analyzing also potential gene-gene interactions with variants in NOD2/CARD15, IL23R, ATG16L1, and IRGM genes, and investigating genotype-phenotype correlation.

METHODS

In all, 1808 patients with IBD, 855 with Crohn's disease (CD) and 953 with ulcerative colitis (UC), including 539 patients with their initial diagnosis <19 years of age, and 651 controls were analyzed for SNPs rs9858542 and rs3197999.

RESULTS

BSN and MST1 were significantly associated with either CD (P(rs9858542) 2.5 x 10(-7); P(rs3197999) 3.9 x 10(-7)), and UC (P(rs9858542) = 3.1 x 10(-4); P(rs3197999) = 8 x 10(-4)). Prevalence of these variants was significantly increased in both adult and early-onset IBD patients. After stepwise logistic regression, the 2 variants were associated in adult UC with distal colitis (P(rs9858542) = 0.013, odds ratio [OR] = 2.04, 95% confidence interval [CI] = 1.16-3.59; P(rs3197999) = 0.018, OR 1.9, 95% CI 1.2-3.3), while the rs3197999 variant was inversely associated with occurrence of extraintestinal manifestations in adult CD(P = 0.017, OR 0.6, 95% CI 0.4-0.9).

CONCLUSIONS

We confirmed the association of BSN and MST1 with IBD susceptibility, either in the adult or the early-onset cohorts. These variants appeared to influence either the distal location of the disease in the UC cohort and extraintestinal manifestations in CD patients.

Role of genetics in prediction of disease course and response to therapy

The clinical course of Crohn’s disease and ulcerative colitis is highly variable between patients, and this has therapeutic implications. A number of clinical features have been identified, which predict a mild or more severe outcome. However, several of these are subjective and/or not persistent over time. With the progress in genetics research in inflammatory bowel disease (IBD), genetic markers are increasingly being proposed to improve stratification of patients. Genetics have the major advantage of being stable over time and not prone to subjective interpretation. Nevertheless, none of the genetic variants associated with particular outcomes have shown sufficient sensitivity or specificity to have been implemented in daily management. Along the same line of thinking, pharmacogenetics or the study of association between variability in drug response and genetic variation has also received more attention as part of the endeavor for personalized medicine. The ultimate goal in this area of medicine is to adapt medication to a patient’s specific genetic background and therefore improve on efficacy and safety rates. Although pharmacogenetic studies have been performed for all classes of drugs applied in IBD, few have generated consistent findings or have been replicated. The only genetic test approved for clinical practice is thiopurine S-methyltransferase testing prior to starting treatment with thiopurine analogues. The other reported associations have suffered from lack of confirmation or still need replication efforts. Nevertheless, the importance and necessity of pharmacogenetic studies will increase further as more therapeutic classes are being developed.

Response to medical treatment in patients with Crohn's disease: the role of NOD2/CRAD15, disease phenotype, and age of diagnosis

PURPOSE

Factors influencing response to medications in Crohn's disease (CD) patients are not fully understood. We aimed to evaluate the relationships between NOD2/CARD15 mutations, disease phenotype and age of CD diagnosis and response to medical treatment with systemic steroids, azathioprine (AZA) or 6-mercaptopurine (6-MP), and infliximab.

METHODS

A retrospective medical records analysis was made of patients previously tested for the CD-associated NOD2/CARD15 mutations. Harvey- Bradshaw score was used to assess remission or response to therapy.

RESULTS

CD-associated NOD2/CARD15 mutations were not related to the rate of steroids dependency or clinical response to AZA/6-MP and infliximab. Steroid dependency was associated with colonic involvement. Thirty-three of 127 (26%) patients with colonic disease were steroid dependent, compared with 7/72 (9.7%) patients with isolated small bowel disease (ISBD), (p = 0.009). ISBD was mildly associated with a better remission/response to AZA/6-MP treatment. Disease behavior and age of diagnosis were not related to response to therapy.

CONCLUSIONS

Response to treatment with systemic steroids, AZA/6-MP and infliximab are not related to NOD2/CARD15 mutations, age of diagnosis and disease behavior. Patients with colonic disease have higher rates of steroid dependency.

Crosstalk between TNF and glucocorticoid receptor signaling pathways

TNF is a Janus-faced protein. It possesses impressive anti-tumor activities, but it is also one of the strongest known pro-inflammatory cytokines, which hampers its use as a systemic anti-cancer agent. TNF has been shown to play a detrimental role in inflammatory diseases such as rheumatoid arthritis and inflammatory bowel disease. Glucocorticoids are strongly anti-inflammatory and exert their therapeutic effects through binding to their receptor, the glucocorticoid receptor. Therefore, glucocorticoids have been used for over half a century for the treatment of inflammatory diseases. However, many patients are or become resistant to the therapeutic effects of glucocorticoids. Inflammatory cytokines have been suggested to play an important role in this steroid insensitivity or glucocorticoid resistance. This review aims to highlight the mechanisms of mutual inhibition between TNF and GR signaling pathways.

Pharmacogenomics in the treatment of inflammatory bowel disease

In recent years, the benefits of early aggressive treatment paradigms for inflammatory bowel disease have emerged. Symptomatic improvement is no longer considered adequate; instead, the aim of treatment has become mucosal healing and altered natural history. Nonetheless, we still fail to achieve these end points in a large number of our patients. There are many reasons why patients fail to respond or develop toxicity when exposed to drugs used for inflammatory bowel disease, but genetic variation is likely to account for a significant proportion of this. Some examples, notably thiopurine methyltransferase polymorphism in thiopurine treatment, are already established in clinical practice. We present a review of the expanding literature in this field, highlighting many interesting developments in pharmacogenomics applied to inflammatory bowel disease and, where possible, providing guidance on the translation of these developments into clinical practice.

Research progress in susceptible genes of inflammatory bowel disease

The mechanism of inflammatory bowel disease (IBD) is partially understood, but it is certain that a genetic predisposition, through the inheritance of a number of contributory genetic polymorphisms, contributes to the pathogenesis of IBD. These variant forms of genes may be associated with an abnormal response to normal luminal bacteria. Those genes that have been consistently associated with IBD thus far primarily fall into one of three classes: those affecting bacterial recognition, those affecting immune response, and a third group affecting mucosal transport polarity or mucosal transporter function. This article reviews the IBD related genes mentioned above.

Associations between ABCB1/MDR1 gene polymorphisms and Crohn's disease: a gene-wide study in a pediatric population

BACKGROUND

Functional studies support the involvement of the MDR1 gene in the pathways leading to Crohn's disease (CD). Two common single nucleotide polymorphisms (SNPs), C3435T and G2677T/A, thought to alter the function of the corresponding P-glycoprotein, have shown inconsistent associations with CD. We investigated whether DNA variants in the MDR1 gene were associated with susceptibility for CD and specific phenotypes in children.

METHODS

A case-control study was conducted at 3 gastroenterology clinics across Canada. Children with CD and population- or hospital-based controls were included. CD cases were classified using the Montreal Classification. Thirteen tag-SNPs and the C3435T variant in the MDR1 gene were genotyped. Single-SNP allelic, genotype as well as gene-wide haplotype associations with CD and its phenotypes at diagnosis were assessed.

RESULTS

A total of 270 CD cases and 336 controls were studied. Most cases were male (56.3%), had disease location L3+/-L4 (58.1%), and an inflammatory phenotype B1+/-p (88.5%). Allelic association analysis revealed that SNP rs17327442 was significantly associated with overall susceptibility to CD (odds ratio [OR] = 0.72, 95% confidence interval [CI] = 0.50-0.99, P = 0.04) but this association did not withstand corrections for multiple testing (q-value = 0.56). Genotype-phenotype analysis indicated that 2 SNPs (rs10248420, P = 0.007, q-value = 0.07; rs2032583, P = 0.01, q-value = 0.07) were significantly associated with colonic disease. Five SNPs, rs1128503 (P = 0.02), rs1202184 (P = 0.008), rs1202186 (P = 0.02), rs2091766 (P = 0.03), and rs2235046 (P = 0.03) were nominally associated with noninflammatory CD. Specific haplotypes comprising of the tag-SNPs were significantly associated with either colonic or noninflammatory CD.

CONCLUSIONS

Our comprehensive gene-wide analysis suggests that the MDR1 gene may be associated with clinical phenotypes of CD in children.