Genetics of the innate immune response in inflammatory bowel disease

Diagnostic and therapeutic potential of RNASET2 in Crohn's disease: Disease-risk polymorphism modulates allelic-imbalance in expression and circulating protein levels and recombinant-RNASET2 attenuates pro-inflammatory cytokine secretion

Ribonuclease T2 gene (RNASET2) variants are associated in genome wide association studies (GWAS) with risk for several autoimmune diseases, including Crohn's disease (CD). In T cells, a functional and biological relationship exists between TNFSF15-mediated enhancement of IFN-γ production, mucosal inflammation and RNASET2. Disease risk variants are associated with decreased mRNA expression and clinical characteristics of severe CD; however, functional classifications of variants and underlying molecular mechanisms contributing to pathogenesis remain largely unknown. In this study we demonstrate that allelic imbalance of RNASET2 disease risk variant rs2149092 is associated with transcriptional and post-transcriptional mechanisms regulating transcription factor binding, promoter-transactivation and allele-specific expression. RNASET2 mRNA expression decreases in response to multiple modes of T cell activation and recovers following elimination of activator. In CD patients with severe disease necessitating surgical intervention, preoperative circulating RNASET2 protein levels were decreased compared to non-IBD subjects and rebounded post-operatively following removal of the inflamed region, with levels associated with allelic carriage. Furthermore, overexpression or treatment with recombinant RNASET2 significantly reduced IFN-γ secretion. These findings reveal that RNASET2 cis- and trans-acting variation contributed regulatory complexity and determined expression and provide a basis for linking genetic variation with CD pathobiology. These data may ultimately identify RNASET2 as an effective therapeutic target in a subset of CD patients with severe disease.

Diagnosis and Classification of Fistula from Inflammatory Bowel Disease and Inflammatory Bowel Disease-Related Surgery

Fistula in inflammatory bowel disease (IBD) is a well-known yet poorly understood phenotype. Pathophysiology is largely based on the activation of the epithelial-mesenchymal transition (EMT); however, interactions with the microbiome, genetics, mechanical stress and the presence of stricturing disease, and surgical complications play a role. Perianal penetrating disease represents a more severe phenotype in IBD. Pouch-associated fistula can arise as a result of an anastomotic leak, surgical complications, or Crohn's disease (CD) of the pouch. Classification is site-dependent, includes a range of severity, and informs management. It is important to determine associated symptoms and recognize the complex interplay of underlying etiologies to form the basis of appropriate care.

Effects of Herb-Partitioned Moxibustion on Autophagy and Immune Activity in the Colon Tissue of Rats with Crohn’s Disease

Objective

To investigate the mechanism of action of herb-partitioned moxibustion on CD from the perspective of autophagy and immunity.

Methods

The expression of microtubule-associated protein LC3II and SQSTM1/p62 in the colon tissues was detected by immunohistochemistry. Western blot was used to detect the expression of autophagic and immune-related proteins in the colon, such as LC3II, SQSTM1/p62, Beclin1, ATG16L1, NOD2, IRGM, IL-1β, IL-17, and TNF-β. mRNA levels of immune factors, such as IL-1β, IL-17, and TNF-β, and autophagy signaling molecules, such as PI3KC, AKT1, LKB1, and mTOR, were detected by RT-qPCR.

Results

Herb-partitioned moxibustion reduced the protein levels of ATG16L1, NOD2, IRGM, LC3II, and Beclin1 (P < 0.01) and both the protein and mRNA levels of IL-1β, IL-17, and TNF-β in CD rats (P < 0.01 or P < 0.05), and it also increased the expression of SQSTM1/p62 protein (P < 0.01). The modulatory effects of herb-partitioned moxibustion on ATG16L1, NOD2, IRGM, LC3II, TNF-β, and IL-17 protein and IL-1β protein and mRNA were better than those of mesalazine (P < 0.01 or P < 0.05). Herb-partitioned moxibustion also reduced colon PI3KC, AKT1, and LKB1 mRNA expressions in CD rats (P < 0.01 or P < 0.05) and increased mTOR protein expression (P < 0.05). And the modulatory effect of herb-partitioned moxibustion on AKT1 mRNA was better than that of mesalazine (P < 0.05).

Conclusion

Herb-partitioned moxibustion may inhibit excessively activated autophagy and modulate the expression of immune-related factors by regulating the LKB1-mTOR-PI3KC signal transduction networks, thereby alleviating intestinal inflammation in CD rats.

Overlapping irritable bowel syndrome and inflammatory bowel disease

The pathogenesis of irritable bowel-type symptoms occurring in patients with inflammatory bowel disease who are in apparent remission continues to generate scientific controversy and the interpretation and management of these symptoms, so distressing to the sufferer, represent major challenges for the clinician. On the one hand, these symptoms often satisfy Rome IV criteria for IBS and their occurrence correlates highly with anxiety, a known trigger for IBS. On the other hand, recent studies have shown that many of these patients exhibit subtle inflammatory changes. These observations beg the question: are these symptoms "true" IBS superimposed on IBD, or an active but subclinical form of IBD? While it is certain that earlier studies failed to detect subclinical inflammation, it is also evident that even with the use of sensitive biomarkers for inflammation, such as calprotectin and lactoferrin backed up by pan-endoscopy and biopsy to exclude ongoing inflammatory activity in its most subtle form, the prevalence of IBS-type symptoms remains higher than expected in the IBD patient. Pending further definition of its etiology and pathology, we coined the term irritable inflammatory bowel syndrome (IIBS) to refer to this phenomenon. Here we explore the risk factors for this entity, sift through clues to its pathogenesis and attempt to provide, albeit bereft of a robust evidence base, an approach to its management.

Sodium chloride exacerbates dextran sulfate sodium-induced colitis by tuning proinflammatory and antiinflammatory lamina propria mononuclear cells through p38/MAPK pathway in mice

AIM

To investigate the influence of high salt on dextran sulfate sodium (DSS)-induced colitis in mice and explore the underlying mechanisms of this effect.

METHODS

DSS and NaCl were used to establish the proinflammatory animal model. We evaluated the colitis severity. Flow cytometry was employed for detecting the frequencies of Th1, macrophages and Tregs in spleen, mesenteric lymph node and lamina propria. The important role of macrophages in the promotion of DSS-induced colitis by NaCl was evaluated by depleting macrophages with clodronate liposomes. Activated peritoneal macrophages and lamina propria mononuclear cells (LPMCs) were stimulated with NaCl, and proteins were detected by western blotting. Cytokines and inflammation genes were analyzed by enzyme-linked immunosorbent assay and RT-PCR, respectively.

RESULTS

The study findings indicate that NaCl up-regulates the frequencies of CD11b+ macrophages and CD4+IFN-γ+IL-17+ T cells in lamina propria in DSS-treated mice. CD3+CD4+CD25+Foxp3+ T cells, which can secrete high levels of IL-10 and TGF-β, increase through feedback in NaCl- and DSS-treated mice. Furthermore, clodronate liposomes pretreatment significantly alleviated DSS-induced colitis, indicating that macrophages play a vital role in NaCl proinflammatory activity. NaCl aggravates peritoneal macrophage inflammation by promoting the expressions of interleukin (IL)-1, IL-6 and mouse inducible nitric oxide synthase. Specifically, high NaCl concentrations promote p38 phosphorylation in lipopolysaccharide- and IFN-γ-activated LPMCs mediated by SGK1.

CONCLUSION

Proinflammatory macrophages may play an essential role in the onset and development of NaCl-promoted inflammation in DSS-induced colitis. The underlining mechanism involves up-regulation of the p38/MAPK axis.

Overlapping irritable bowel syndrome and inflammatory bowel disease: less to this than meets the eye?

Though distinct in terms of pathology, natural history and therapeutic approach, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) have some features in common. These include shared symptomatology and largely similar demographics. However, in most instances, clinical presentation, together with laboratory, imaging and endoscopic findings will readily permit the differentiation of active IBD from IBS. More problematic is the situation where a subject with IBD, in apparent remission, continues to complain of symptoms which, in aggregate, satisfy commonly employed criteria for the diagnosis of IBS. Access to methodologies, such the assay for levels of calprotectin in feces, now allows identification of ongoing inflammation in some such individuals and prompts appropriate therapy. More challenging is the IBD patient with persisting symptoms and no detectable evidence of inflammation; is this coincident IBS, IBS triggered by IBD or an even more subtle level of IBD activity unrecognized by available laboratory or imaging methods? Arguments can be advanced for each of these proposals; lacking definitive data, this issue remains unresolved. The occurrence of IBS-type symptoms in the IBD patient, together with some data suggesting a very subtle level of 'inflammation' or 'immune activation' in IBS, raises other questions: is IBS a prodromal form of IBD; and are IBS and IBD part of the spectrum of the same disease? All of the available evidence indicates that the answer to both these questions should be a resounding 'no'. Indeed, the whole issue of overlap between IBS and IBD should be declared moot given their differing pathophysiologies, contrasting natural histories and divergent treatment paths. The limited symptom repertoire of the gastrointestinal tract may well be fundamental to the apparent confusion that has, of late, bedeviled this area.

Association of <i>TLR4</i> and <i>CARD15/NOD2</i> polymorphisms with SCC in Holstein–Friesian cattle

Abstract. Mastitis is one of the most important dairy cattle diseases which results in economic losses in dairy production. Mastitis cases can be classified as subclinical or clinical. All forms of mastitis lead to changes in milk composition and induce an increase in somatic cell count (SCC). SCC is a very important and basic indicator of udder health. An increase in SCC is usually caused by the immune response to the invasion of pathogens contributing to mastitis. The aim of this study was to investigate associations between the polymorphisms of selected genes (TLR4 and CARD15/NOD2) whose products are involved in the identification of pathogen-associated molecular patterns (PAMPs) during the innate immune response to infection, and immunity to mastitis expressed as SCC. The genes under study were also examined for epistatic effects as well as effects of interactions with parity and stages of lactation. In all the studied classes, allele G of TLR4 had a favourable additive effect with negative values, contributing to a lower lnSCC. Allele A of CARD15/NOD2 had a desirable additive effect which varied with time and the changing internal environment during lactation. With regard to the dominance effect, allele A of CARD15/NOD2 was found to be significantly associated with a higher SCC in milk in the first lactation and in the third stage of each single lactation. Moreover, statistically significant epistatic effects were found, in particular additive–additive and dominance–additive interactions were favourably associated with SCC which was lower than expected in the case of no epistasis.

Intestinal and hepatic drug transporters: pharmacokinetic, pathophysiological, and pharmacogenetic roles

The efficacy and safety of pharmacotherapies are determined by the complex processes involved in the interactions between drugs with the human body, including pharmacokinetic aspects. Among pharmacokinetic factors, it has been recognized that drug transporters play critical roles for absorption, distribution and excretion of drugs, regulating the membrane transport of drugs. The vast amounts of information on drug transporters collected in the past 20 years have been organized according to biochemical, molecular, genetic, and clinical analyses. Novel technologies, public databases, and regulatory guidelines have advanced the use of such information in drug development and clinical practice. In this review, we selected some clinically important drug transporters expressed in the intestine and liver, and introduced the research history and current knowledge of their pharmacokinetic, pathophysiological, and pharmacogenetic implications.

Interleukin and interleukin receptor gene polymorphisms in inflammatory bowel diseases susceptibility

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), represents a group of chronic inflammatory disorders caused by dysregulated immune responses in genetically predisposed individuals. Genetic markers are associated with disease phenotype and long-term evolution, but their value in everyday clinical practice is limited at the moment. IBD has a clear immunological background and interleukins play key role in the process. Almost 130 original papers were revised including meta-analysis. It is clear these data are very important for understanding the base of the disease, especially in terms of clinical utility and validity, but text often do not available for the doctors use these in the clinical practice nowadays. We conducted a systematic review of the current literature on interleukin and interleukin receptor gene polymorphisms associated with IBD, performing an electronic search of PubMed Database from publications of the last 10 years, and used the following medical subject heading terms and/or text words: IBD, CD, UC, interleukins and polymorphisms.

The overlap between IBS and IBD: what is it and what does it mean?

The nature and clinical implications of irritable bowel syndrome (IBS)-type symptoms in patients with inflammatory bowel disease (IBD) who are in apparent remission have generated considerable debate. While, on the one hand, these symptoms satisfy Rome III criteria for IBS and their occurrence correlates highly with anxiety, a known trigger for IBS, on the other hand, recent studies have shown that many of these patients exhibit subtle inflammatory changes. Are these symptoms 'true' IBS superimposed on IBD, or an active but sub-clinical form of IBD? We propose a unifying model to explain and reconcile current knowledge on this topic, a model that could provide a conceptual framework for understanding the nature of these symptoms and point towards effective management strategies. We propose that IBS symptoms in IBD patients who are in remission be termed irritable inflammatory bowel syndrome in order to emphasize their unique presentation and etiology and to distinguish them from both IBS and IBD.

Susceptibility to ulcerative colitis in Hungarian patients determined by gene-gene interactions

AIM: To study the inflammatory bowel disease-5 locus (IBD5) and interleukin-23 receptor (IL23R) gene variants in UC patients and test for gene-gene interaction.

METHODS: The study population (n = 625) was comprised of 320 unrelated ulcerative colitis (UC) patients with Caucasian origin and 316 age- and gender-matched, healthy controls. Five variants in the IBD5 locus (IGR2198a_1 rs11739135, IGR2096a_1 rs12521868, IGR2230a_1 rs17622208, SLC22A4 rs1050152 and SLC22A5 rs2631367) and two of the IL23R gene (rs1004819, rs2201841) were analysed. PCR and restriction fragment length polymorphism methods were used for genotyping, the SLC22A4 rs1050152 genotypes were determined by direct sequencing. Interactions and specific genotype combinations of the seven variants were tested by binary logistic regression analysis. The IL23R genotypes were stratified by IBD5 genotypes for further interaction analyses.

RESULTS: For the IL23R rs1004819 A allele we found significantly higher allele frequency (P = 0.032) in UC patients compared to control subjects. The SNP rs1004819 showed significant association with UC risk for carriers (P = 0.004, OR = 1.606; 95%CI: 1.160-2.223) and the SNP rs2201841 for homozygotes (P = 0.030, OR = 1.983; 95%CI: 1.069-3.678). Individually none of the IBD5 markers conferred risk to UC development. There was no evidence for statistical interaction either between IBD5 loci and IL23R genes using logistic regression analysis. After genotype stratification, we could detect a positive association on the background of rs1004819 A allele for SLC22A4 T, SLC22A5 C, IGR2198a_1 C or IGR2096a_1 T allele, the highest OR was calculated in the presence of SLC22A4 T allele (P = 0.005, OR = 2.015; 95%CI: 1.230-3.300). There was no association with UC for any combinations of rs1004819 and IGR2230a_1. The IL23R rs2201841 homozygous genotype and IBD5 carrier status together did not confer susceptibility for UC.

CONCLUSION: The present study has shown that UC susceptibility genes are likely to act in a complex interactive manner similar to CD.

Multidrug resistance 1 gene polymorphisms may determine Crohn's disease behavior in patients from Rio de Janeiro

OBJECTIVES

Conflicting data from studies on the potential role of multidrug resistance 1 gene polymorphisms in inflammatory bowel disease may result from the analysis of genetically and geographically distinct populations. Here, we investigated whether multidrug resistance 1 gene polymorphisms are associated with inflammatory bowel diseases in patients from Rio de Janeiro.

METHODS

We analyzed 123 Crohn's disease patients and 83 ulcerative colitis patients to determine the presence of the multidrug resistance 1 gene polymorphisms C1236T, G2677T and C3435T. In particular, the genotype frequencies of Crohn's disease and ulcerative colitis patients were analyzed. Genotype-phenotype associations with major clinical characteristics were established, and estimated risks were calculated for the mutations.

RESULTS

No significant difference was observed in the genotype frequencies of the multidrug resistance 1 G2677T/A and C3435T polymorphisms between Crohn's disease and ulcerative colitis patients. In contrast, the C1236T polymorphism was significantly more common in Crohn's disease than in ulcerative colitis (p = 0.047). A significant association was also found between the multidrug resistance 1 C3435T polymorphism and the stricturing form of Crohn's disease (OR: 4.13; p = 0.009), whereas no association was found with penetrating behavior (OR: 0.33; p = 0.094). In Crohn's disease, a positive association was also found between the C3435T polymorphism and corticosteroid resistance/refractoriness (OR: 4.14; p = 0.010). However, no significant association was found between multidrug resistance 1 gene polymorphisms and UC subphenotypic categories.

CONCLUSION

The multidrug resistance 1 gene polymorphism C3435T is associated with the stricturing phenotype and an inappropriate response to therapy in Crohn's disease. This association with Crohn's disease may support additional pathogenic roles for the multidrug resistance 1 gene in regulating gut-microbiota interactions and in mediating fibrosis. Understanding the effects of several drugs associated with multidrug resistance 1 gene variants may aid in the selection of customized therapeutic regimens.

Central role of the gut epithelial barrier in the pathogenesis of chronic intestinal inflammation: lessons learned from animal models and human genetics

The gut mucosa is constantly challenged by a bombardment of foreign antigens and environmental microorganisms. As such, the precise regulation of the intestinal barrier allows the maintenance of mucosal immune homeostasis and prevents the onset of uncontrolled inflammation. In support of this concept, emerging evidence points to defects in components of the epithelial barrier as etiologic factors in the pathogenesis of inflammatory bowel diseases (IBDs). In fact, the integrity of the intestinal barrier relies on different elements, including robust innate immune responses, epithelial paracellular permeability, epithelial cell integrity, as well as the production of mucus. The purpose of this review is to systematically evaluate how alterations in the aforementioned epithelial components can lead to the disruption of intestinal immune homeostasis, and subsequent inflammation. In this regard, the wealth of data from mouse models of intestinal inflammation and human genetics are pivotal in understanding pathogenic pathways, for example, that are initiated from the specific loss of function of a single protein leading to the onset of intestinal disease. On the other hand, several recently proposed therapeutic approaches to treat human IBD are targeted at enhancing different elements of gut barrier function, further supporting a primary role of the epithelium in the pathogenesis of chronic intestinal inflammation and emphasizing the importance of maintaining a healthy and effective intestinal barrier.

The role of the innate immune system in granulomatous disorders

The dynamic structure of the granuloma serves to protect the body from microbiological challenge. This organized aggregate of immune cells seeks to contain this challenge and protect against dissemination, giving host immune cells a chance to eradicate the threat. A number of systemic diseases are characterized by this specialized inflammatory process and granulomas have been shown to develop at multiple body sites and in various tissues. Central to this process is the macrophage and the arms of the innate immune response. This review seeks to explore how the innate immune response drives this inflammatory process in a contrast of diseases, particularly those with a component of immunodeficiency. By understanding the genes and inflammatory mechanisms behind this specialized immune response, will guide research in the development of novel therapeutics to combat granulomatous diseases.

Deficiency of N-acetylgalactosamine in O-linked oligosaccharides of IgA is a novel biologic marker for Crohn's disease

BACKGROUND

Ideal biomarkers are required to be developed for the diagnosis and prediction of the treatment of inflammatory bowel disease (IBD). We have reported that alteration of N-linked oligosaccharides of immunoglobulin (Ig) G is a novel diagnostic marker of IBD. Oligosaccharide alterations of IgA, however, have not been investigated in IBD patients.

METHODS

N- and O-linked oligosaccharides of serum IgA purified from 32 patients with Crohn's disease (CD), 30 patients with ulcerative colitis (UC), and 30 healthy volunteers (HV) were analyzed with high-performance liquid chromatography and mass spectrometry. Enzymes related to oligosaccharide attachment were investigated.

RESULTS

N-linked oligosaccharides of IgA were not different between IBD and HV. In contrast, the number of N-acetylgalactosamines per hinge glycopeptide (GalNAc/HP) in the O-linked oligosaccharides of IgA was significantly decreased in patients with CD compared with UC and HV. GalNAc/HP had high sensitivity and specificity for discriminating between CD and HV based on receiver operating characteristic analysis. Lower GalNAc/HP was associated with more severe disease activity of CD. Changes in GalNAc/HP levels in 6 weeks after treatment with infliximab were associated with the clinical activity of CD at 30 weeks. GalNAc transferase expression of naïve B cells and extent of GalNAc attachment in IgA were significantly decreased by interleukin-21 in vitro.

CONCLUSIONS

The number of GalNAc attached in the IgA O-linked glycans of CD patients was significantly decreased, and strongly correlated with the clinical activity. Alterations of GalNAc attachment in IgA could be useful as a novel diagnostic and prognostic marker of CD.

[Dipeptidyl peptidase IV in inflammatory bowel diseases (DPP IV/CD26)]

Inflammatory bowel diseases (Crohn's disease, ulcerative colitis, undetermined colitis) are a group of chronic autoimmune inflammatory diseases distinguished by recurrent inflammation of various parts of the gastrointestinal (GI) system and presenting a significant public health problem. Despite large basic and clinical research, the aetiology of these diseases and the pathogenesis of inflammation itself remain elusive. Previous studies have confirmed a causal relationship between mediators of inflammatory response and molecules involved in the regulation of their biological activity, especially proteases. The aim of this review is to summarise earlier findings on different aspects of inflammatory bowel diseases, paying particular attention to the involvement of dipeptidyl peptidase IV (CD26 molecule, DPP IV/CD26) in the etiopathogenesis of inflammatory processes in the GI tract. Animal studies of colitis have significantly contributed to the understanding and treatment of these diseases, investigations of ulcerative colitis (DSS-colitis) and Crohn's disease (TNBS-colitis) on the murine model in particular.

A common genetic background could explain early-onset Crohn's disease

Crohn's disease (CD) is a multifactorial disease, in which environmental, microbial and genetic factors play important roles. CD is characterized by a chronic granulomatous inflammation by necrotic scarring with aspects of full-thickness wall. In spite of affecting mainly young adults, sometimes, CD can be present in the first year of life (early onset Crohn disease, EOCD) showing an unpredictable course and being often more severe than at older ages. In this paper we propose the hypothesis that EOCD patients should be analyzed using a Mendelian approach with family studies aimed to identify new loci directly involved in the early onset Crohn's disease. So we will leave the classic association study approach used until now for the identification of genes responsible for susceptibility to CD and propose linkage family analysis as alternative and powerful tool for the identification of new genetic variants associated with familiar cases of EOCD.

Role of ATG16L, NOD2 and IL23R in Crohn’s disease pathogenesis

Inflammatory bowel disease is a group of diseases that includes Crohn’s disease (CD) and ulcerative colitis. CD is characterized as a chronic inflammatory disease of the gastrointestinal tract, ranging from the mouth to the anus. Although there are gross pathological and histological similarities between CD and Johne’s disease of cattle, the cause of CD remains controversial. It is vital to understand fully the cause of this disease because it affects approximately 500 000 people in North America and Europe. It ranges from 27 to 48 cases per 100 000 people. There are many theories on the cause of CD ranging from possible association with environmental factors including microorganisms to imbalance in the intestinal normal flora of the patients. Regardless of the environmental trigger, there is strong evidence that a genetic disposition is a major key in acquiring CD. Many studies have proven the link between mutations in the ATG16L, NOD2/CARD15, IBD5, CTLA4, TNFSF15 and IL23R genes, and CD. The purpose of this review is to examine all genetic aspects and theories of CD, including up to date multiple population studies performed worldwide.

Genetic polymorphisms of glutathione S-transferases are associated with ulcerative colitis in central China

The present study aimed to investigate the association between genetic polymorphisms of glutathione S-transferases (GSTs) and susceptibility to ulcerative colitis (UC) in central China. The prevalence of GSTM1, GSTT1, and GSTP1 gene polymorphisms were examined using polymerase chain reaction methods in 270 consecutive UC patients and 623 age- and sex-matched healthy controls. The frequencies of the GSTM1(null) and GSTT1(null) as well as GSTP1 (Val/Val) genotypes were significantly higher in UC patients than in the controls (70.74% vs. 41.74%, P = 0.0001; 64.82% vs. 47.19%, P = 0.0001; and 48.89% vs. 34.35%, P = 0.0004, respectively). When the UC patients were stratified according to clinical features, we found that the frequencies of the GSTT1(null) and GSTP1 (Val/Val) genotypes but not the GSTM1(null) genotype were significantly higher in patients with distal colitis than in extensive colitis (P = 0.0007, P = 0.001, and P = 0.271, respectively). However, these variant GST genotypes were not significantly linked to severity of the disease (P > 0.05). GST variant genotypes are strongly correlated with prevalence and extent but not with severity of UC in the Hubei Han population in central China.

Discovering genetic variants in Crohn's disease by exploring genomic regions enriched of weak association signals

BACKGROUND

A meta-analysis has re-analysed previous genome-wide association scanning definitively confirming eleven genes and further identifying 21 new loci. However, the identified genes/loci still explain only the minority of genetic predisposition of Crohn's disease.

AIMS

To identify genes weakly involved in disease predisposition by analysing chromosomal regions enriched of single nucleotide polymorphisms with modest statistical association.

METHODS

We utilized the WTCCC data set evaluating 1748 CD and 2938 controls. The identification of candidate genes/loci was performed by a two-step procedure: first of all chromosomal regions enriched of weak association signals were localized; subsequently, weak signals clustered in gene regions were identified. The statistical significance was assessed by non parametric permutation tests.

RESULTS

The cytoband enrichment analysis highlighted 44 regions (P≤0.05) enriched with single nucleotide polymorphisms significantly associated with the trait including 23 out of 31 previously confirmed and replicated genes. Importantly, we highlight further 20 novel chromosomal regions carrying approximately one hundred genes/loci with modest association. Amongst these we find compelling functional candidate genes such as MAPT, GRB2 and CREM, LCT, and IL12RB2.

CONCLUSION

Our study suggests a different statistical perspective to discover genes weakly associated with a given trait, although further confirmatory functional studies are needed.

L-Carnitine and intestinal inflammation

The intestinal barrier is one of the most dynamic surfaces of the body. It is here where a single layer of epithelial cells mediates the intricate encounters that occur between the host's immune system and a multitude of potential threats present in the intestinal lumen. Several key factors play an important role in the final outcome of this interaction, including the state of oxidative stress, the level of activation of the immune cells, and the integrity of the epithelial barrier. This chapter describes the main evidence demonstrating the impact that l-carnitine has on each of these factors. These findings, combined with the demonstrated safety profile of l-carnitine, underscore the potential therapeutic value of l-carnitine supplementation in humans suffering from intestinal inflammation and highlight the functional data supporting an association between Crohn's disease and mutations in the l-carnitine transporter genes.

Genetics of childhood-onset inflammatory bowel disease

Nearly a third of inflammatory bowel disease (IBD) patients present in childhood or adolescence, with epidemiological and natural history studies clearly demonstrating a rising incidence in this population. Although early-onset disease has a distinct phenotype, such as more extensive disease at onset and rapid progression, two recent genome-wide association studies (GWAS) carried out exclusively in this age group have demonstrated marked genetic similarities to adult disease. Although these parallels exist, this review will focus on the novel regions associated with early-onset IBD susceptibility identified by these early-onset GWAS. These new loci reaffirm the dysregulated pathways previously implicated in adult IBD pathogenesis and provide further insight into the pathophysiology of intestinal inflammation. The newly identified loci and expression data suggest mutations in genes encoding IL-27, which is involved in Th17 effector cell physiology; MTMR3, which we demonstrate is an essential component of autophagy; and CAPN10, which is necessary in regulating endoplasmic reticulum stress. In addition, the roles of PSMG1, TNFRSF6B, ZMIZ1 and SMAD3 are also discussed in relation to abnormal protein degradation and the secondary immune response. It is clear that with increasing technology our understanding of IBD pathogenesis is deepening at the genomic level and that the use of early patient selection coupled with ongoing work on therapeutic targets will lead to improved disease-modifying treatments in the near future.

Association of genetic variants of mannan-binding (MBL) lectin-2 gene, MBL levels and function in ulcerative colitis and Crohn's disease

Ulcerative colitis and Crohn's disease are the two major forms of inflammatory bowel disease (IBD). A series of reports have hypothesized interplay of genetic and environmental factors in the pathogenesis of IBD. Polymorphism in the mannan-binding lectin-2 (MBL-2) gene is known to affect the structural assembly and function thereby predisposing subjects to various diseases. The present study was designed to evaluate effect of MBL-2 gene polymorphism on MBL levels and function in IBD patients. Genomic DNA was isolated from blood samples collected from 157 ulcerative colitis, 42 Crohn's disease and 204 control subjects. Genotyping for different polymorphic sites at exon1 of MBL-2 gene was performed by refractory mutation system-PCR and amplification followed by restriction digestion (PCR-RFLP). Serum MBL concentration and C4 deposition levels were estimated using ELISA. Mannan-binding lectin-2 genotypic variants were calculated in IBD and healthy controls. The frequency of single nucleotide polymorphisms at codon 54 was significantly higher in ulcerative colitis patients than controls (P < 0.0001). Ulcerative colitis patients with 'codon 54'-variation showed low serum MBL concentrations coupled with altered MBL function compared to controls. In conclusion, single nucleotide polymorphism in the MBL-2 gene is an important risk factor significantly affecting MBL levels and function in the development of ulcerative colitis among Indians.

[A case of ulcerative colitis found in a patient whose parent has Crohn's disease]

Inflammatory bowel diseases (IBD) is heterogeneous, chronic relapsing disorder. Inappropriate and exaggerated immune response for the luminal antigen is known as a main pathogenesis. Genetic, infectious, and environmental factors are responsible for unbalanced immune response, but the definite pathogenesis is still unclear. Genetic factor is the most important role of all. That is based on high concordance rate of identical twins and family history. The incident rate and prevalence of IBD for the Asian population is relatively lower than Western population, and the lack of NOD2 or TLR4 genetic polymorphisms in Korea and Japanese population suggests the difference in genetic background between Asian and Western population. In Korea, the case of familial aggregation of IBD is pretty rare. We report a case of the daughter with ulcerative colitis and her mother with Crohn's disease who have a -159C/T promoter polymorphism of CD14 gene for IBD.

Aberrant responses to TLR agonists in pediatric IBD patients; the possible association with increased production of Th1/Th17 cytokines in response to candida, a luminal antigen

Toll like receptors (TLR) regulate innate immune responses sensing byproducts of intestinal microbiota. We examined responses to TLR agonists in children with inflammatory bowel disease (IBD). Peripheral blood mononuclear cells (PBMC) obtained from children with IBD [Crohn's disease (CD, n = 10), ulcerative colitis (UC, n = 10)], children with non-IgE-mediated food allergy (NFA, n = 20), and controls (n = 15) were tested for their production of proinflammatory and counter-regulatory cytokines with TLR agonists in comparison with their cytokine production against milk protein and candida. IBD patients were all in the inactive state. IBD PBMC produced more IL-6 with all the TLR agonists tested than controls. CD PBMC produced more counter-regulatory cytokines with TLR agonists, while UC PBMC produced more IL-1ss and IL-10 with TLR 7/8 agonist than controls. Cytokine production by NFA PBMC did not differ from controls. CD but not UC PBMC produced more IFN-gamma and IL-17 with candida. Aberrant responses to TLR agonists may be associated with increase in IFN-gamma/IL-17 production against candida in CD children.

OCTN1 variant L503F is associated with familial and sporadic inflammatory bowel disease

PURPOSE

A two-allele haplotype of TC (OCTN1 rs1050152 and OCTN2 -207G→C) is associated with Crohn's disease (CD). The association has been replicated in different populations, but also failed in some studies. The present study is to replicate the association of OCTN1 rs1050152 and examine another variant rs272879 with familial and sporadic inflammatory bowel disease (IBD) in a cohort from central Pennsylvania, USA.

METHODS

The study samples (n=465) included 212 inflammatory bowel disease patients (CD=115, UC=97), including 103 familial (CD=55, UC=46) and 111 sporadic (CD=60, UC=51) IBD, 139 non-IBD family members from a familial IBD registry, and 114 unrelated healthy controls. A total of 12 OCTN1 variants within exonic sequences were examined. Two nonsynonymous SNPs, rs1050152 (L503F) and rs272879 (L395V) were genotyped by a PCR-based RFLP/cRFLP method and statistically analyzed. These samples with an additional 141 unrelated healthy samples were also genotyped for rs1050152 using the SNPlex™ Genotyping System.

RESULTS

The OCTN1 rs1050152 is associated with CD (OR=1.745, 95% CI=1.019-2.990, χ²=4.129, p=0.042) and with IBD (OR=1.68, 95% CI=1.052-2.676, χ²=4.732, p=0.030); while the variant rs272879 is not associated with IBD, CD or ulcerative colitis (UC). The distribution of the rs1050152 variant showed a high level of the T allele in male UC (OR=2.585, 95% CI=1.139-5.869, p=0.023) and IBD (OR=2.039, 95% CI=1.024-4.059, p=0.042) patients, and in female CD patients (OR=2.329, 95% CI=1.038-5.226, ρ value=0.039).

CONCLUSION

The present results replicated the association of the OCTN1 rs1050152 (L503F) variant with CD and IBD overall. A weak gender-specific effect of rs1050152 (L503F) on male UC and female CD was observed.

Noninvasive methods in evaluation of inflammatory bowel disease: where do we stand now? An update

The inflammatory bowel diseases, consisting of Crohn's disease, ulcerative colitis and indeterminate colitis, are distinguished by idiopathic and chronic inflammation of the digestive tract. The distinction between inflammatory bowel diseases and functional bowel disorders, such as irritable bowel syndrome, can be complex because they often present with similar symptoms. Rapid and inexpensive noninvasive tests that are sensitive, specific and simple are needed to prevent patient discomfort, delay in diagnosis, and unnecessary costs. None of the current commercially available serological biomarker tests can be used as a stand-alone diagnostic in clinics. Instead, these are used as an adjunct to endoscopy in diagnosis and prognosis of the disease. Along these lines,, fecal lactoferrin and calprotectin tests seem to be one step further from other tests with larger number of studies, higher sensitivity and specificity and wider availability.

Interaction of the major inflammatory bowel disease susceptibility alleles in Crohn’s disease patients

AIM: To investigate the interaction of interleukin-23 receptor (IL23R) (rs1004819 and rs2201841), autophagy-related 16-like 1 (ATG16L1) (rs2241880), caspase recruitment domain-containing protein 15 (CARD15) genes, and IBD5 locus in Crohn’s disease (CD) patients.

METHODS: A total of 315 unrelated subjects with CD and 314 healthy controls were genotyped. Interactions and specific genotype combinations of a total of eight variants were tested. The variants of IBD5 locus (IGR2198a_1 rs11739135 and IGR2096a_1 rs12521868), CARD15 (R702W rs2066845 and L1007fs rs2066847), ATG16L1 (rs2241880) and IL23R (rs1004819, rs2201841) genes were genotyped by PCR-RFLP, the G908R (rs2066844) in CARD15 was determined by direct sequencing.

RESULTS: The association of ATG16L1 T300A with CD was confirmed [P = 0.004, odds ratio (OR) = 1.69, 95% CI: 1.19-2.41], and both IL23R variants were found to represent significant risk for the disease (P = 0.008, OR = 2.05, 95% CI: 1.20-3.50 for rs1004819 AA; P < 0.001, OR = 2.97, 95% CI: 1.65-5.33 for rs2201841 CC). Logistic regression analysis of pairwise interaction of the inflammatory bowel disease (IBD) loci indicated that IL23R, ATG16L1, CARD15 and IBD5 (IGR2198a_1) contribute independently to disease risk. We also analysed the specific combinations by pair of individual ATG16L1, IL23R rs1004819, rs2201841, IGR2198a_1, IGR2096a_1 and CARD15 genotypes for disease risk influence. In almost all cases, the combined risk of susceptibility pairs was higher in patients carrying two different risk-associated gene variants together than individuals with just one polymorphism. The highest OR was found for IL23R rs2201841 homozygous genotype with combination of positive CARD15 status (P < 0.001, OR = 9.15, 95% CI: 2.05-40.74).

CONCLUSION: The present study suggests a cumulative effect of individual IBD susceptibility loci.

The genetics of Crohn's disease

From epidemiological data, based on concordance data in family studies, via linkage analysis to genome-wide association studies, we and others have accumulated robust evidence implicating more than 30 distinct genomic loci involved in the genetic susceptibility to Crohn's disease (CD). These loci encode genes involved in a number of homeostatic mechanisms: innate pattern recognition receptors (NOD2/CARD15, TLR4, CARD9), the differentiation of Th17-lymphocytes (IL-23R, JAK2, STAT3, CCR6, ICOSLG), autophagy (ATG16L1, IRGM, LRRK2), maintenance of epithelial barrier integrity (IBD5, DLG5, PTGER4, ITLN1, DMBT1, XBP1), and the orchestration of the secondary immune response (HLA-region, TNFSF15/TL1A, IRF5, PTPN2, PTPN22, NKX2-3, IL-12B, IL-18RAP, MST1). While many of these loci also predispose to pediatric CD, an additional number of childhood-onset loci have been identified recently (e.g., TNFRSF6B). Not only has the identification of these loci improved our understanding of the pathophysiology of CD, this knowledge also holds real promise for clinical practice.

Filaggrin loss-of-function variants are associated with atopic comorbidity in pediatric inflammatory bowel disease

BACKGROUND

Pediatric inflammatory bowel disease (IBD) has a high prevalence of coexistent atopy. Filaggrin (FLG) loss-of-function variants (null-alleles) are associated with eczema and asthma in association with eczema. The aim was to assess the contribution of FLG null-alleles to pediatric IBD susceptibility and to coexistent atopy (eczema, asthma, allergic rhinitis, or food allergy).

METHODS

FLG variants (R501X and 2282del4) were genotyped in 403 children with IBD, 683 parents, and 996 population controls.

RESULTS

In all, 11% of IBD patients carried at least 1 FLG null-allele compared to 11% of population controls (P > 0.4). Carriage of 1 or more null-alleles in patients with atopy (present in 52% of IBD patients) differed from IBD patients without atopy (14% versus 6%, P = 0.01; odds ratio [OR] 2.4, 95% confidence interval [CI] 1.2-5.1). The effect of FLG null-alleles was strongest for eczema (19% versus 7%, P = 0.0003; OR 3.3, 95% CI 1.7-6.6) and food allergy (28% versus 8%, P = 0.0001; OR 4.5, 95% CI 2.0-10.0). The presence of more than 1 atopic disease tended to increase the associated OR: eczema + asthma (23% versus 7%, P = 0.001; OR 3.9, 95% CI 1.6-9.1), eczema + asthma + allergic rhinitis (29% versus 7%, P = 0.0006; OR 5.4, 95% CI 1.9-15.4) and eczema + asthma + allergic rhinitis + food allergy (45% versus 6%, P < 10(-4); OR 12.2, 95% CI 3.2-46.3). Logistic regression analysis of IBD cases confirmed the association of carriage of an FLG null-allele with atopy (P = 0.01; OR 2.4, 95% CI 1.2-5.1) and co-occurrence of different forms of atopy (P = 0.003; OR 3.5, 95% CI 1.5-8.1).

CONCLUSIONS

Filaggrin null-alleles have no effect on IBD susceptibility but contribute to coexistent eczema and food allergy.

Association studies of the SAS-ZFAT, IL-23R, IFIH1 and FOXP3 genes in autoimmune thyroid disease

Autoimmune thyroid diseases (AITDs) are complex diseases caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility in combination with external factors, such as dietary iodine, is believed to initiate the autoimmune response against thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence in the development of AITDs. Various techniques have been employed to identify genes contributing to the etiology of AITDs, including candidate gene analysis and whole-genome screening. These studies have enabled the identification of several loci (genetic regions) that are linked to AITDs and, in some of these loci, putative AITD-susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD) and Hashimoto's thyroiditis (HT), and some are common to both diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune-modifying genes (e.g., HLA, CTLA-4 and PTPN22) and thyroid-specific genes (e.g., TSHR and Tg). In this special report, we focus on the newest genes identified and not on those previously identified, such as HLA and CTLA-4, for which there are many reviews.

Hepcidin and inflammatory bowel disease: dual role in host defence and iron homoeostasis

OBJECTIVE

Hepcidin is an endogenous antimicrobial peptide with a key role in iron homoeostasis. Hepcidin is similar to defensin, the deficiency of which is associated with Crohn's disease. To date there has been no validated method to reliably assay serum hepcidin. We studied iron indices in inflammatory bowel disease (IBD) including hepcidin.

DESIGN

We assessed serum hepcidin concentrations (using a newly developed competitive radioimmunoassay) and ferritin in patients with IBD. Haematinics including serum soluble transferrin receptor, serum iron, serum vitamin B12 and red cell folate levels were also measured. The hepcidin results were compared with a control group of healthy volunteers from the local community.

SETTING

This study was based in a hospital.

PATIENTS

Sixty-one patients with IBD (51 patients with ulcerative colitis and 10 with Crohn's disease). Their mean hepcidin results were compared with 25 healthy controls.

MAIN OUTCOME MEASURE

hepcidin concentration in serum samples in IBD patients compared with normal volunteers.

RESULTS

We found significantly low serum hepcidin levels in patients with IBD. The hepcidin levels were low in IBD patients without iron deficiency anaemia as evidenced by normal ferritin and serum iron levels (n=41, mean hepcidin 6.81 ng/ml, SEM 1.2) and in IBD patients with iron deficiency anaemia (n=18, mean hepcidin 4.14 ng/ml, SEM 0.72) compared with healthy controls (n=25, mean hepcidin 15.3 ng/ml, SEM 3.14) (P=0.0045 and P=0.0050 on unpaired t-tests, respectively). We also measured IL-6 (enzyme-linked immunosorbent assay method, Abcam plc) in 21 of the 61 patients with IBD and compared the results with samples from 10 healthy volunteers. The IL-6 level was significantly higher (P=0.0222 on unpaired t-tests) in this group of IBD patients (n=21, IL-6 mean 2.94 pg/ml, SEM 0.64) compared with controls (n=10, IL-6 mean 0.663 pg/ml SEM 0.14). A significant positive correlation (Pearson's correlation coefficient r=0.6331) was present between hepcidin and IL-6, but not between hepcidin and serum soluble transferrin receptor (r=-0.235).

CONCLUSION

The low hepcidin results in IBD patients may reflect a causal or perpetuator effect on intestinal inflammation.

Anti-Saccharomyces cerevisiae antibodies status is associated with oral involvement and disease severity in Crohn disease

OBJECTIVES

To determine anti-Saccharomyces cerevisiae antibodies (ASCA) status and its relation to disease phenotype in patients with inflammatory bowel disease (IBD).

PATIENTS AND METHODS

A total of 301 Scottish patients with early-onset IBD-197 Crohn disease (CD), 76 ulcerative colitis (UC), 28 indeterminate colitis (IC)-and 78 healthy control individuals were studied. ASCA status (IgA, IgG) was determined by enzyme-linked immunosorbent assay. ASCA status was then analyzed in relation to CD phenotype.

RESULTS

Patients with CD had a higher prevalence of ASCA than patients with UC and healthy controls: 82/197 versus 12/76, odds ratio (OR) 3.80 (1.93-7.50) and 82/197 versus 6/78, OR 8.56 (3.55-20.62), respectively. Univariate analysis showed that positive ASCA status was associated with oral CD (17/25 vs 59/153, OR 3.39 [1.38-8.34]), perianal CD (39/77 vs 38/108, OR 1.89 [1.04-3.44]) and the presence of granulomata (63/132 vs 15/52, OR 2.25 [1.13-4.48]) and also with markers of disease severity: raised C-reactive protein (44/90 vs 12/49, OR 2.95[1.36-6.37]), hypoalbuminemia (44/85 vs 20/74, OR 2.28[1.19-4.37]), and surgery (27/49 vs 54/147, OR 2.11 [1.10-4.06]). From multivariate analysis, the presence of oral disease (adjusted P = 0.001, OR 22.22 [3.41-142.86]) and hypoalbuminemia (adjusted P = 0.01, OR 4.78 [1.40-16.39]) was found to be independently associated with ASCA status. No association was demonstrated between ASCA and IBD candidate genes.

CONCLUSIONS

Patients with CD had a higher prevalence of ASCA than did other patients with IBD. ASCA status described patients with CD who had a specific phenotype, showing an association with markers of disease severity and oral CD involvement.

New serological biomarkers of inflammatory bowel disease

Serological biomarkers in inflammatory bowel disease (IBD) are a rapidly expanding list of non-invasive tests for objective assessments of disease activity, early diagnosis, prognosis evaluation and surveillance. This review summarizes both old and new biomarkers in IBD, but focuses on the development and characterization of new serological biomarkers (identified since 2007). These include five new anti-glycan antibodies, anti-chitobioside IgA (ACCA), anti-laminaribioside IgG (ALCA), anti-manobioside IgG (AMCA), and antibodies against chemically synthesized (Σ) two major oligomannose epitopes, Man α-1,3 Man α-1,2 Man (ΣMan3) and Man α-1,3 Man α-1,2 Man α-1,2 Man (ΣMan4). These new biomarkers serve as valuable complementary tools to existing biomarkers not only in differentiating Crohn’s disease (CD), ulcerative colitis (UC), normal and other non-IBD gut diseases, but also in predicting disease involvement (ileum vs colon), IBD risk (as subclinical biomarkers), and disease course (risk of complication and surgery). Interestingly, the prevalence of the antiglycan antibodies, including anti-Saccharomyces cerevisiae antibodies (ASCA), ALCA and AMCA, was found to be associated with single nucleotide polymorphisms (SNPs) of IBD susceptible genes such as NOD2/CARD15, NOD1/CARD4, toll-like receptors (TLR) 2 and 4, and β-defensin-1. Furthermore, a gene dosage effect was observed: anti-glycan positivity became more frequent as the number of NOD2/CARD15 SNPS increased. Other new serum/plasma IBD biomarkers reviewed include ubiquitination factor E4A (UBE4A), CXCL16 (a chemokine), resistin, and apolipoprotein A-IV. This review also discusses the most recent studies in IBD biomarker discovery by the application of new technologies such as proteomics, fourier transform near-infrared spectroscopy, and multiplex enzyme-linked immunosorbent assay (ELISA)’s (with an emphasis on cytokine/chemokine profiling). Finally, the prospects of developing more clinically useful novel diagnostic algorithms by incorporating new technologies in serological biomarker profiling and integrating multiple biomarkers with bioinformatics analysis/modeling are also discussed.

Lack of evidence for association of primary sclerosing cholangitis and primary biliary cirrhosis with risk alleles for Crohn's disease in Polish patients

BACKGROUND

Numerous papers have addressed the association of mutations and polymorphisms of susceptibility genes with autoimmune inflammatory disorders. We investigated whether polymorphisms that confer susceptibility to Crohn's disease could be classified also as predisposing factors for the development of primary sclerosing cholangitis and primary biliary cirrhosis in Polish patients.

METHODS

The study included 60 patients with CD, 77 patients with PSC, of which 61 exhibited IBD (40 UC, 8 CD, and 13 indeterminate colitis), and 144 patients with PBC. All the patients were screened against Crohn's disease associating genetic polymorphisms. The polymorphisms were chosen according to previously confirmed evidence for association with Crohn's disease, including Pro268Ser, Arg702Trp, Gly908Arg and 1007fs in NOD2/CARD15, Leu503Phe/-207G>C in SLC22A4/OCTN1/SLC22A5/OCTN2, Arg30Gln in DLG5, Thr300Ala in ATG16L1, and Arg381Gln, His3Gln and exon-3'UTR in IL23R. Genotyping was carried out using TaqMan SNP genotyping assays.

RESULTS

We confirmed a strong association between three NOD2/CARD15 gene variants (Pro268Ser, OR = 2.52, 95% CI = 1.34-4.75); (Arg702Trp, OR = 6.65, 95% CI = 1.99-22.17); (1007fs, OR = 9.59, 95% CI = 3.94-23.29), and a weak association between both the protective OCTN1/OCTN2 CC haplotype (OR = 0.28, 95% CI = 0.08-0.94), and a variant of ATG16L1 gene (Thr300Ala, OR = 0.468, 95% CI = 0.24-0.90) with Crohn's disease. In contrast, none of the polymorphisms exhibited association with susceptibility to primary sclerosing cholangitis and primary biliary cirrhosis, including a group of primary sclerosing cholangitis patients with concurrent IBD.

CONCLUSION

Although the clinical data indicate non-random co-occurrence of inflammatory bowel disease and primary sclerosing cholangitis, consistently with the previously published studies, no genetic association was found between the genetic variants predisposing to Crohn's disease and hepatobiliary autoimmune disorders. However, since estimation of genetic variant disproportion is limited by sample size, these negative results may also indicate that eventually shared genetic predispositions are too little to be captured by small patient groups.

Clinical significance of NOD2/CARD15 and Toll-like receptor 4 gene single nucleotide polymorphisms in inflammatory bowel disease

AIM: To evaluate the role of genetic factors in the pathogenesis of Crohn’s disease (CD) and ulcerative colitis (UC), we investigated the single nucleotide polymorphisms (SNPs) of NOD2/CARD15 (R702W, G908R and L1007finsC), and Toll-like receptor 4 (TLR4) genes (D299G and T399I) in a selected inflammatory bowel disease (IBD) population coming from Southern Italy.

METHODS: Allele and genotype frequencies of NOD2/CARD15 (R702W, G908R and L1007finsC) and TLR4 (D299G and T399I) SNPs were examined in 133 CD patients, in 45 UC patients, and in 103 healthy controls. A genotype-phenotype correlation was performed.

RESULTS: NOD2/CARD15 R702W mutation was significantly more frequent in CD (9.8%) than in controls (2.4%, P = 0.001) and in UC (2.3%, P = 0.03). No significant difference was found between UC patients and control group (P > 0.05). In CD and UC patients, no significant association with G908R variant was found. L1007finsC SNP showed an association with CD (9.8%) compared with controls (2.9%, P = 0.002) and UC patients (2.3%, P = 0.01). Moreover, in CD patients, G908R and L1007finsC mutations were significantly associated with different phenotypes compared to CD wild-type patients. No association of IBD with the TLR4 SNPs was found in either cohort (allele frequencies: D299G-controls 3.9%, CD 3.7%, UC 3.4%, P > 0.05; T399I-controls 2.9%, CD 3.0%, UC 3.4%, P > 0.05).

CONCLUSION: These findings confirm that, in our IBD patients selected from Southern Italy, the NOD2/CARD15, but not TLR4 SNPs, are associated with increased risk of CD.

The relevance of kinin B1 receptor upregulation in a mouse model of colitis

BACKGROUND AND PURPOSE

Kinins are implicated in many pathophysiological conditions, and recent evidence has suggested their involvement in colitis. This study assessed the role of the kinin B1 receptors in a mouse model of colitis.

EXPERIMENTAL APPROACH

Colitis was induced in mice by 2,4,6-trinitrobenzene sulphonic acid (TNBS), and tissue damage and myeloperoxidase activity were assessed. B1 receptor induction was analysed by organ bath studies, binding assay and reverse transcription PCR.

KEY RESULTS

TNBS-induced colitis was associated with tissue damage, neutrophil infiltration and time-dependent increase of colon B1 receptor-mediated contraction, with the maximal response observed at 72 h. The upregulation of the B1 receptor at this time point was also confirmed by means of binding studies. B1 receptor mRNA levels were elevated as early as 6 h after colitis induction and remained high for up to 48 h. TNBS-evoked tissue damage and neutrophil influx were reduced by the selective B1 receptor antagonist SSR240612, and in B1 receptor knockout mice. In vivo treatment with inhibitors of protein synthesis, nuclear factor-kappaB activation, inducible nitric oxide synthase (iNOS) or tumour necrosis factor alpha (TNFalpha) significantly reduced B1 receptor agonist-induced contraction. Similar results were observed in iNOS and TNF receptor 1-knockout mice.

CONCLUSIONS AND IMPLICATIONS

These results provide convincing evidence on the role of B1 receptors in the pathogenesis of colitis. Therefore, the blockade of kinin B1 receptors might represent a new therapeutic option for treating inflammatory bowel diseases.

Low body mass not vitamin D receptor polymorphisms predict osteoporosis in patients with inflammatory bowel disease

BACKGROUND

Osteoporosis is a recognized complication of inflammatory bowel disease (IBD). Aim To investigate the role of environmental factors and vitamin D receptor (VDR) variants on the prevalence of osteoporosis.

METHODS

DEXA scans and case note review were performed on 440 IBD patients from 1997 to 2006. All the IBD patients and 240 healthy controls were genotyped for VDR variants Taq-1 and Apa-1 using PCR-RFLP.

RESULTS

Osteoporosis and osteopenia rates were 15% and 18% for IBD, 16% and 18% for Crohn's disease (CD) and 13% and 19% for ulcerative colitis, respectively. On univariate analysis of the CD patients, low body mass index (BMI, <18.5) and smoking status (P = 0.008 and 0.005 respectively) were associated with osteoporosis and osteopenia. Low BMI was also associated with osteoporosis on multivariate analysis in CD (P = 0.021, OR 5.83, CI 1.31-25.94). No difference was observed between Taq-1 and Apa-1 VDR polymorphisms in IBD, CD, ulcerative colitis and healthy controls. However, CD males were more likely to carry the variant Taq-1 polymorphism than healthy controls males (P = 0.0018, OR 1.94, CI 1.28-2.92) and female CD patients (P = 0.0061, OR 1.60, CI 1.17-2.44).

CONCLUSIONS

In this well-phenotyped cohort of IBD patients, a relatively low prevalence of osteoporosis was observed. Low BMI was the only independent risk factor identified to be associated with osteoporosis.

The myeloid differentiation factor 88 (MyD88) is required for CD4+ T cell effector function in a murine model of inflammatory bowel disease

Abnormal T cell responses to commensal bacteria are involved in the pathogenesis of inflammatory bowel disease. MyD88 is an essential signal transducer for TLRs in response to the microflora. We hypothesized that TLR signaling via MyD88 was important for effector T cell responses in the intestine. TLR expression on murine T cells was examined by flow cytometry. CD4(+)CD45Rb(high) T cells and/or CD4(+)CD45Rb(low)CD25(+) regulatory T cells were isolated and adoptively transferred to RAG1(-/-) mice. Colitis was assessed by changes in body weight and histology score. Cytokine production was assessed by ELISA. In vitro proliferation of T cells was assessed by [(3)H]thymidine assay. In vivo proliferation of T cells was assessed by BrdU and CFSE labeling. CD4(+)CD45Rb(high) T cells expressed TLR2, TLR4, TLR9, and TLR3, and TLR ligands could act as costimulatory molecules. MyD88(-/-) CD4(+) T cells showed decreased proliferation compared with WT CD4(+) T cells both in vivo and in vitro. CD4(+)CD45Rb(high) T cells from MyD88(-/-) mice did not induce wasting disease when transferred into RAG1(-/-) recipients. Lamina propria CD4(+) T cell expression of IL-2 and IL-17 and colonic expression of IL-6 and IL-23 were significantly lower in mice receiving MyD88(-/-) cells than mice receiving WT cells. In vitro, MyD88(-/-) T cells were blunted in their ability to secrete IL-17 but not IFN-gamma. Absence of MyD88 in CD4(+)CD45Rb(high) cells results in defective T cell function, especially Th17 differentiation. These results suggest a role for TLR signaling by T cells in the development of inflammatory bowel disease.

The wolf in sheep's clothing: the role of interleukin-6 in immunity, inflammation and cancer

Recent discoveries involving the cytokine interleukin (IL)-6 have originated from diverse disciplines, revealing roles in biological processes that are likewise varied. The most novel findings suggest a connection between inflammation and diseases, such as insulin resistance associated with diabetes mellitus and cancer, which had not or only weakly been appreciated previously. The IL-6 pathway is one of the mechanisms linking inflammation to these disease processes. In addition, new evidence points toward IL-6 as one of the mediators coordinating the interface between adaptive and innate immunity. Here, we review the evidence linking IL-6 to inflammatory diseases and cancer.

NOD1 gene E266K polymorphism is associated with disease susceptibility but not with disease phenotype or NOD2/CARD15 in Hungarian patients with Crohn's disease

BACKGROUND

NOD1/CARD4, a member of the pattern-recognition receptor family, is a perfect candidate as a susceptibility gene for Crohn's disease. Since only limited and conflicting data are available on G796A polymorphisms in inflammatory bowel disease patients, we set out to study the effect of this polymorphism on the susceptibility and course of Crohn's disease in the Hungarian population.

METHODS

Four hundred thirty-four unrelated Crohn's disease patients (age at presentation: 28.6+/-9.6 years, female/male: 210/224, duration of Crohn's disease: 8.2+/-6.9 years) and 200 healthy subjects (blood donors) and 136 non-inflammatory bowel disease gastrointestinal controls with chronic gastritis were investigated. NOD1 G796A was detected by using polymerase chain reaction/restriction fragment length polymorphism. Detailed clinical phenotypes were determined by reviewing the medical charts.

RESULTS

The frequencies of the variant alleles of NOD1 G796A differed significantly between the Crohn's disease patients and both healthy (GG 49.5% vs. 67%; AG 41.5% vs. 28%; and AA 9.0% vs. 5.2%; p<0.0001) and non-inflammatory bowel disease controls with chronic gastritis. Carriage of the single nucleotide polymorphism of NOD1 G796A proved to be a highly significant risk factor for Crohn's disease compared to both healthy (p<0.0001, OR: 2.1, 95% CI: 1.5-2.9) and non-inflammatory bowel disease controls with chronic gastritis (p=0.008). Significant associations were not found between the different genotypes and the demographic data on the patients or the clinical characteristics of Crohn's disease. The different polymorphisms of pattern-recognition receptors (e.g. NOD2/CARD15 SNP8, SNP12 and SNP13 mutations, the TLR4 D299G polymorphism and NOD1 G796A) did not reveal a mutual basis.

CONCLUSIONS

Our results suggest that carriage of the NOD1 G796A mutation increases susceptibility for Crohn's disease in the Hungarian population.

The genetics of inflammatory bowel disease

Great progress in the understanding of the molecular genetics of inflammatory bowel disease (IBD) has been made over the last 10 years. Strong epidemiological evidence, based initially on concordance data in twin/family studies, led to the application of genome-wide linkage analysis involving multiply affected families and the identification of a number of susceptibility loci. Further characterization of the IBD1 locus on chromosome 16 led to the discovery of the NOD2/CARD15 gene as the first susceptibility gene in Crohn's disease for 2001. This landmark finding has led to a redirection of basic research in IBD with interest focused principally on regulation of the innate immune response and mucosal barrier function. Within the last year, the use of genome-wide association studies has provided new insights into primary pathogenetic mechanisms; several new genes such as the Interleukin-23 receptor (IL23R) and ATG16L1 (autophagy-related 16-like 1) genes are strongly implicated. Overall, these studies promise to change our fundamental understanding of IBD pathophysiology and to have implications for clinical practice.

Inflammatory bowel disease: progress and current concepts of etiopathogenesis

Over the past few years, none of the numerous conditions that are grouped under the broad designation of 'chronic inflammatory or autoimmune disorders' has undergone as much scientific and clinical progress as the two main forms of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC). Progress has occurred in all major areas relevant to IBD pathogenesis, which include the external environment, genetics, microbial factors, and the immune system. This review presents an update on the specific major advances that have occurred in each of these four areas, briefly discusses the therapeutic implications of the observed progress, and points out the additional work that needs to be accomplished in the next few years to reach a full understanding of IBD etiopathogenesis.

The genetic basis of thyroid autoimmunity

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto's thyroiditis (HT), are prevalent autoimmune diseases, affecting up to 5% of the general population. AITDs arise due to interplay between environmental and genetic factors. In the past decade, significant progress has been made in our understanding of the genetic contribution to the etiology of AITDs. Excitingly, several AITD susceptibility genes have been identified and characterized. Some of these susceptibility genes are specific to either GD or HT, while others confer susceptibility to both conditions. The first AITD susceptibility gene locus identified was the Human-Leukocyte-Antigen DR (HLA-DR) gene locus. Subsequently, a quintet of non-HLA genes, including the cytotoxic T lymphocyte antigen (CTLA-4), CD40, protein tyrosine phosphatase-22 (PTPN22), thyroglobulin, and thyroid-stimulating hormone receptor (TSHR) gene, has been shown to contribute to the susceptibility to AITDs. Recently, the mechanisms by which these new AITD genes predispose to AITDs have been dissected. In this review, we overview and highlight the recent data on the genes predisposing to AITDs and the putative mechanisms by which they confer susceptibility to disease.