Functional consequences of NOD2 (CARD15) mutations

Intestinal Inflammation and Regeneration-Interdigitating Processes Controlled by Dietary Lipids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a disease of chronic inflammatory conditions of the intestinal tract due to disturbance of the inflammation and immune system. Symptoms of IBD include abdominal pain, diarrhea, bleeding, reduced weight, and fatigue. In IBD, the immune system attacks the intestinal tract's inner wall, causing chronic inflammation and tissue damage. In particular, interlukin-6 and interlukin-17 act on immune cells, including T cells and macrophages, to amplify the immune responses so that tissue damage and morphological changes occur. Of note, excessive calorie intake and obesity also affect the immune system due to inflammation caused by lipotoxicity and changes in lipids supply. Similarly, individuals with IBD have alterations in liver function after sustained high-fat diet feeding. In addition, excess dietary fat intake, along with alterations in primary and secondary bile acids in the colon, can affect the onset and progression of IBD because inflammatory cytokines contribute to insulin resistance; the factors include the release of inflammatory cytokines, oxidative stress, and changes in intestinal microflora, which may also contribute to disease progression. However, interfering with de novo fatty acid synthase by deleting the enzyme acetyl-CoA-carboxylase 1 in intestinal epithelial cells (IEC) leads to the deficiency of epithelial crypt structures and tissue regeneration, which seems to be due to Lgr5+ intestinal stem cell function. Thus, conflicting reports exist regarding high-fat diet effects on IBD animal models. This review will focus on the pathological basis of the link between dietary lipids intake and IBD and will cover the currently available pharmacological approaches.

Selected Cytokines and Metalloproteinases in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a collective term for two diseases: ulcerative colitis (UC) and Crohn's disease (CD). There are many factors, e.g., genetic, environmental and immunological, that increase the likelihood of these diseases. Indicators of IBDs include extracellular matrix metalloproteinases (MMPs). The aim of this review is to present data on the role of selected cytokines and metalloproteinases in IBD. In recent years, more and more transcriptomic studies are emerging. These studies are improving the characterization of the cytokine microenvironment inside inflamed tissue. It is observed that the levels of several cytokines are consistently increased in inflamed tissue in IBD, both in UC and CD. This review shows that MMPs play a major role in the pathology of inflammatory processes, cancer, and IBD. IBD-associated inflammation is associated with increased expression of MMPs and reduced ability of tissue inhibitors of metalloproteinases (TIMPs) to inhibit their action. In IBD patients in tissues that are inflamed, MMPs are produced in excess and TIMP activity is not sufficient to block MMPs. This review is based on our personal selection of the literature that was retrieved by a selective search in PubMed using the terms "Inflammatory bowel disease" and "pathogenesis of Inflammatory bowel diseases" that includes systematic reviews, meta-analyses, and clinical trials. The involvement of the immune system in the pathophysiology of IBD is reviewed in terms of the role of the cytokines and metalloproteinases involved.

Activation and regulation mechanisms of NOD-like receptors based on structural biology

Innate immunity is a primary defense system against microbial infections. Innate immune pattern recognition receptors (PRRs) play pivotal roles in detection of invading pathogens. When pathogens, such as bacteria and viruses, invade our bodies, their components are recognized by PRRs as pathogen-associated molecular patterns (PAMPs), activating the innate immune system. Cellular components such as DNA and RNA, acting as damage-associated molecular patterns (DAMPs), also activate innate immunity through PRRs under certain conditions. Activation of PRRs triggers inflammatory responses, interferon-mediated antiviral responses, and the activation of acquired immunity. Research on innate immune receptors is progressing rapidly. A variety of these receptors has been identified, and their regulatory mechanisms have been elucidated. Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) constitute a major family of intracellular PRRs and are involved in not only combating pathogen invasion but also maintaining normal homeostasis. Some NLRs are known to form multi-protein complexes called inflammasomes, a process that ultimately leads to the production of inflammatory cytokines and induces pyroptosis through the proteolytic cascade. The aberrant activation of NLRs has been found to be associated with autoimmune diseases. Therefore, NLRs are considered targets for drug discovery, such as for antiviral drugs, immunostimulants, antiallergic drugs, and autoimmune disease drugs. This review summarizes our recent understanding of the activation and regulation mechanisms of NLRs, with a particular focus on their structural biology. These include NOD2, neuronal apoptosis inhibitory protein (NAIP)/NLRC4, NLR family pyrin domain containing 1 (NLRP1), NLRP3, NLRP6, and NLRP9. NLRs are involved in a variety of diseases, and their detailed activation mechanisms based on structural biology can aid in developing therapeutic agents in the future.

The Intestinal Microbiota May Be a Potential Theranostic Tool for Personalized Medicine

The human intestine is colonized by a huge number of microorganisms from the moment of birth. This set of microorganisms found throughout the human body, is called the microbiota; the microbiome indicates the totality of genes that the microbiota can express, i.e., its genetic heritage. Thus, microbiota participates in and influences the proper functioning of the organism. The microbiota is unique for each person; it differs in the types of microorganisms it contains, the number of each microorganism, and the ratio between them, but mainly it changes over time and under the influence of many factors. Therefore, the correct functioning of the human body depends not only on the expression of its genes but also on the expression of the genes of the microorganisms it coexists with. This fact makes clear the enormous interest of community science in studying the relationship of the human microbiota with human health and the incidence of disease. The microbiota is like a unique personalized "mold" for each person; it differs quantitatively and qualitatively for the microorganisms it contains together with the relationship between them, and it changes over time and under the influence of many factors. We are attempting to modulate the microbial components in the human intestinal microbiota over time to provide positive feedback on the health of the host, from intestinal diseases to cancer. These interventions to modulate the intestinal microbiota as well as to identify the relative microbiome (genetic analysis) can range from dietary (with adjuvant prebiotics or probiotics) to fecal transplantation. This article researches the recent advances in these strategies by exploring their advantages and limitations. Furthermore, we aim to understand the relationship between intestinal dysbiosis and pathologies, through the research of resident microbiota, that would allow the personalization of the therapeutic antibiotic strategy.

Association of NOD1, NOD2, PYDC1 and PYDC2 genes with Behcet's disease susceptibility and clinical manifestations

Purpose: Behçet's disease (BD) is an autoinflammatory disease with clinical manifestations such as mucocutaneous, ocular, vascular, gastrointestinal, musculoskeletal and central nervous system involvement. Features of innate and adaptive immunity and inflammasome pathways have been claimed in the pathogenesis of BD. We aimed to investigate the roles of NOD1, NOD2, PYDC1 and PYDC2 genes in the genetic predisposition of BD.Materials and Methods: Genetic variations of NOD1 (rs2075820 and rs2075818) and NOD2 (R334Q and R334W) genes were explored in 68 BD patients and 70 controls with PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) approach. PYDC1 and PYDC2 gene variants were investigated by Sanger sequencing.Results: The polymorphism of rs2075820 (NOD1 G/A) had a statistically significant difference between the BD and controls, AA genotype was 2.460-fold protective. When compared in terms of cardiovascular involvement in BD patients, AA genotype was increased the risk of cardiovascular involvement 4.286-fold. There was a significant difference between BD and controls in rs2075818 (NOD1 G/C) polymorphism and CC genotype increased the risk of BD by 3.780-fold. In terms of rs2075818 variants, there was a statistically significant difference between BD patients with ocular lesions, joints, cardiovascular and gastrointestinal involvement and controls. There was a significant difference between the patients with joint involvement and controls and the risk increased of 3.310-fold.Conclusion: The data shed new light on the association between polymorphisms of NOD1 gene and BD and clinicial manifestations. However, NOD2, PYDC1 and PYDC2 genes were not associated with BD in the Turkish population.

Mutation spectrum of NOD2 reveals recessive inheritance as a main driver of Early Onset Crohn's Disease

Inflammatory bowel disease (IBD), clinically defined as Crohn’s disease (CD), ulcerative colitis (UC), or IBD-unclassified, results in chronic inflammation of the gastrointestinal tract in genetically susceptible hosts. Pediatric onset IBD represents ≥ 25% of all IBD diagnoses and often presents with intestinal stricturing, perianal disease, and failed response to conventional treatments. NOD2 was the first and is the most replicated locus associated with adult IBD, to date. However, its role in pediatric onset IBD is not well understood. We performed whole-exome sequencing on a cohort of 1,183 patients with pediatric onset IBD (ages 0–18.5 years). We identified 92 probands with biallelic rare and low frequency NOD2 variants accounting for approximately 8% of our cohort, suggesting a Mendelian inheritance pattern of disease. Additionally, we investigated the contribution of recessive inheritance of NOD2 alleles in adult IBD patients from a large clinical population cohort. We found that recessive inheritance of NOD2 variants explains ~ 7% of cases in this adult IBD cohort, including ~ 10% of CD cases, confirming the observations from our pediatric IBD cohort. Exploration of EHR data showed that several of these adult IBD patients obtained their initial IBD diagnosis before 18 years of age, consistent with early onset disease. While it has been previously reported that carriers of more than one NOD2 risk alleles have increased susceptibility to Crohn’s Disease (CD), our data formally demonstrate that recessive inheritance of NOD2 alleles is a mechanistic driver of early onset IBD, specifically CD, likely due to loss of NOD2 protein function. Collectively, our findings show that recessive inheritance of rare and low frequency deleterious NOD2 variants account for 7–10% of CD cases and implicate NOD2 as a Mendelian disease gene for early onset Crohn’s Disease.

Human Melioidosis

The causative agent of melioidosis, Burkholderia pseudomallei, a tier 1 select agent, is endemic in Southeast Asia and northern Australia, with increased incidence associated with high levels of rainfall. Increasing reports of this condition have occurred worldwide, with estimates of up to 165,000 cases and 89,000 deaths per year. The ecological niche of the organism has yet to be clearly defined, although the organism is associated with soil and water. The culture of appropriate clinical material remains the mainstay of laboratory diagnosis. Identification is best done by phenotypic methods, although mass spectrometric methods have been described. Serology has a limited diagnostic role. Direct molecular and antigen detection methods have limited availability and sensitivity. Clinical presentations of melioidosis range from acute bacteremic pneumonia to disseminated visceral abscesses and localized infections. Transmission is by direct inoculation, inhalation, or ingestion. Risk factors for melioidosis include male sex, diabetes mellitus, alcohol abuse, and immunosuppression. The organism is well adapted to intracellular survival, with numerous virulence mechanisms. Immunity likely requires innate and adaptive responses. The principles of management of this condition are drainage and debridement of infected material and appropriate antimicrobial therapy. Global mortality rates vary between 9% and 70%. Research into vaccine development is ongoing.

Pediatric Sarcoidosis: A Review with Emphasis on Early Onset and High-Risk Sarcoidosis and Diagnostic Challenges

Sarcoidosis is a non-necrotizing granulomatous inflammatory syndrome with multisystemic manifestations. We performed a systematic review of sarcoidosis in the pediatric population with particular emphases on early onset sarcoidosis, high-risk sarcoidosis, and newly reported or unusual sarcoid-related diseases. Blau Syndrome and early onset sarcoidosis/ BS-EOS are seen in children younger than five years old presenting with extra-thoracic manifestations but usually without lymphadenopathy and/or pulmonary involvement. The prevalence of high-risk sarcoidosis is very low in children and is further limited by the difficulty of diagnosis in symptomatic children and underdiagnosis in subclinical or asymptomatic patients. Reports of sarcoidal syndromes in users of E-cigarette/marijuana/other flavorings and their induction in cancer immunotherapies are of interests and may be challenging to differentiate from metastatic malignancy. The diagnostic considerations in pediatric sarcoidosis are to support a compatible clinicoradiographic presentation and the pathologic findings of non-necrotizing granulomas by ruling out granulomas of infective etiology. There is no absolutely reliable diagnostic test for sarcoidosis at present. The use of endoscopic bronchial ultrasound (EBUS) and transbronchial fine needle aspiration (TBNA) sampling of intrathoracic lymph nodes and lung, and for superficially accessible lesions, with cytopathological assessment and pathological confirmations provide fair diagnostic yield and excellent patient safety profile in children.

Inflammatory bowel diseases and spondyloarthropathies: From pathogenesis to treatment

Spondyloarthropathies (SpA) include many different forms of inflammatory arthritis and can affect the spine (axial SpA) and/or peripheral joints (peripheral SpA) with Ankylosing spondylitis (AS) being the prototype of the former. Extra-articular manifestations, like uveitis, psoriasis and inflammatory bowel disease (IBD) are frequently observed in the setting of SpA and are, in fact, part of the SpA classification criteria. Bowel involvement seems to be the most common of these manifestations. Clinically evident IBD is observed in 6%-14% of AS patients, which is significantly more frequent compared to the general population. Besides, it seems that silent microscopic gut inflammation, is evident in around 60% in AS patients. Interestingly, occurrence of IBD has been associated with AS disease activity. For peripheral SpA, two different forms have been proposed with diverse characteristics. Of note, SpA (axial or peripheral) is more commonly observed in Crohn's disease than in ulcerative colitis. The common pathogenetic mechanisms that explain the link between IBD and SpA are still ill-defined. The role of dysregulated microbiome along with migration of T lymphocytes and other cells from gut to the joint ("gut-joint" axis) has been recognized, in the context of a genetic background including associations with alleles inside or outside the human leukocyte antigen system. Various therapeutic modalities are available with monoclonal antibodies against tumour necrosis factor, interleukin-23 and interleukin-17, being the most effective. Both gastroenterologists and rheumatologists should be alert to identify the co-existence of these conditions and ideally follow-up these patients in combined clinics.

Anti-commensal IgG Drives Intestinal Inflammation and Type 17 Immunity in Ulcerative Colitis

Inflammatory bowel disease is a chronic, relapsing condition with two subtypes, Crohn's disease (CD) and ulcerative colitis (UC). Genome-wide association studies (GWASs) in UC implicate a FCGR2A variant that alters the binding affinity of the antibody receptor it encodes, FcγRIIA, for immunoglobulin G (IgG). Here, we aimed to understand the mechanisms whereby changes in FcγRIIA affinity would affect inflammation in an IgA-dominated organ. We found a profound induction of anti-commensal IgG and a concomitant increase in activating FcγR signaling in the colonic mucosa of UC patients. Commensal-IgG immune complexes engaged gut-resident FcγR-expressing macrophages, inducing NLRP3- and reactive-oxygen-species-dependent production of interleukin-1β (IL-1β) and neutrophil-recruiting chemokines. These responses were modulated by the FCGR2A genotype. In vivo manipulation of macrophage FcγR signal strength in a mouse model of UC determined the magnitude of intestinal inflammation and IL-1β-dependent type 17 immunity. The identification of an important contribution of IgG-FcγR-dependent inflammation to UC has therapeutic implications.

Alterations in nucleotide-binding oligomerization domain-2 expression, pathway activation, and cytokine production in Yao syndrome

Yao syndrome (YAOS) is a systemic autoinflammatory disease (SAID), formerly termed nucleotide-binding oligomerization domain-2 (NOD2)-associated autoinflammatory disease. Due to the recent identification of YAOS, the molecular mechanisms underlying its disease pathogenesis are unclear. With specific NOD2 variants as characteristic genotypic features of YAOS, our study examined NOD2 expression, transcript splicing, signaling pathway activation, and cytokine profiles in peripheral blood mononuclear cells (PBMCs) from 10 YAOS patients and six healthy individuals. All participants were genotyped for NOD2 variants; all YAOS patients were heterozygous for the NOD2 IVS8⁺¹⁵⁸ variant (IVS8⁺¹⁵⁸) and four patients also carried a concurrent NOD2 R702W variant (IVS8⁺¹⁵⁸/R702W haplotype). Resembling other SAIDs, plasma levels of TNFα, IL-1β, IL-6, IFNγ, and S100A12 were unaltered in YAOS patients. Intron-8 splicing of NOD2 transcripts was unaffected by carriage of NOD2 IVS8⁺¹⁵⁸. However, NOD2 transcript level and basal p38 mitogen-activated protein kinase (MAPK) activity were significantly elevated in PBMCs from IVS8⁺¹⁵⁸ YAOS patients. Moreover, these patients' cells had elevated basal IL-6 secretion that was enhanced by muramyl dipeptide (MDP) stimulation. Tocilizumab treatment of a YAOS IVS8⁺¹⁵⁸ patient resulted in marked clinical improvement. In contrast, MDP-stimulated NF-κB activity was uniquely suppressed in haplotype IVS8⁺¹⁵⁸/R702W patients, as was TNFα secretion. Our study demonstrates for the first time that NOD2 expression and pathway activation are aberrant in YAOS, and specific NOD2 genotypes result in distinct NOD2 expression and cytokine profiles. These findings may also help select therapeutic strategies in the future.

Dextran sodium sulfate colitis murine model: An indispensable tool for advancing our understanding of inflammatory bowel diseases pathogenesis

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are complex diseases that result from the chronic dysregulated immune response in the gastrointestinal tract. The exact etiology is not fully understood, but it is accepted that it occurs when an inappropriate aggressive inflammatory response in a genetically susceptible host due to inciting environmental factors occurs. To investigate the pathogenesis and etiology of human IBD, various animal models of IBD have been developed that provided indispensable insights into the histopathological and morphological changes as well as factors associated with the pathogenesis of IBD and evaluation of therapeutic options in the last few decades. The most widely used experimental model employs dextran sodium sulfate (DSS) to induce epithelial damage. The DSS colitis model in IBD research has advantages over other various chemically induced experimental models due to its rapidity, simplicity, reproducibility and controllability. In this manuscript, we review the newer publicized advances of research in murine colitis models that focus upon the disruption of the barrier function of the intestine, effects of mucin on the development of colitis, alterations found in microbial balance and resultant changes in the metabolome specifically in the DSS colitis murine model and its relation to the pathogenesis of IBD.

Crohn's Disease: Genetics Update

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

Nucleotide-binding oligomerization domain (NOD) signaling defects and cell death susceptibility cannot be uncoupled in X-linked inhibitor of apoptosis (XIAP)-driven inflammatory disease

The X-linked inhibitor of apoptosis (XIAP) protein has been identified as a key genetic driver of two distinct inflammatory disorders, X-linked lymphoproliferative syndrome 2 (XLP-2) and very-early-onset inflammatory bowel disease (VEO-IBD). Molecularly, the role of XIAP mutations in the pathogenesis of these disorders is unclear. Recent work has consistently shown XIAP to be critical for signaling downstream of the Crohn's disease susceptibility protein nucleotide-binding oligomerization domain-containing 2 (NOD2); however, the reported effects of XLP-2 and VEO-IBD XIAP mutations on cell death have been inconsistent. In this manuscript, we describe a CRISPR-mediated genetic system for cells of the myeloid lineage in which XIAP alleles can be replaced with disease-associated XIAP variants expressed at endogenous levels to simultaneously study inflammation-related cell death and NOD2 signaling. We show that, consistent with previous studies, NOD2 signaling is critically dependent on the BIR2 domain of XIAP. We further used this system to reconcile the aforementioned inconsistent XIAP cell death data to show that XLP-2 and VEO-IBD XIAP mutations that exhibit a loss-of-function NOD2 phenotype also lower the threshold for inflammatory cell death. Last, we identified and studied three novel patient XIAP mutations and used this system to characterize NOD2 and cell death phenotypes driven by XIAP. The results of this work support the role of XIAP in mediating NOD2 signaling while reconciling the role of XLP-2 and VEO-IBD XIAP mutations in inflammatory cell death and provide a set of tools and framework to rapidly test newly discovered XIAP variants.

Casting the critical regions in nucleotide binding oligomerization domain 2 protein: a signature mediated structural dynamics approach

Nucleotide binding oligomerization domain 2 (NOD2), a protein involved in the first line defence mechanism has a pivotal role in innate immunity. Impaired function of this protein is implicated in disorders such as Blau syndrome and Crohn's disease. Since an altered function is linked to protein's structure, we framed a systematic strategy to interpret the structure-function relationship of the protein. Initiated with mutation-based pattern prediction and identified a distant ortholog (DO) of NOD2 from which the intra-residue interaction network was elucidated. The network was used to identify hotspots that serve as critical points to maintain the stable architecture of the protein. Structural comparison of NOD2 domains with a DO revealed the minimal number of intra-protein interactions required by the protein to maintain the structural fold. In addition, the conventional molecular dynamics simulation emphasized the conformational transitions at hot spot residues between native NOD2 domains and its respective mutants (G116R, R42W and R54A) structures. The analysis of intra-protein interactions globally and the displacement of residues locally around the mutational site revealed loss of several critical bonds and residues vital for the protein's function. Conclusively we report, about 10 residues in leucine-rich repeat, 13 residues in NOD and 6 residues in CARD domain are required by the NOD2 to maintain its function. This protocol will help the researchers to achieve for more prospective studies to attest druggable site utility in discovering novel drug candidates.

Association of NOD1 and NOD2 polymorphisms with Guillain-Barré syndrome in Northern Indian population

BACKGROUND

Nucleotide oligomerization domain (NOD) proteins are cytosolic pattern recognition receptors that respond to bacterial substrate and induce NF-κB activation in host. Association of NOD polymorphisms have been studied in many autoimmune disorders, however its role in Guillain-Barré syndrome (GBS) remains unknown. We have investigated NOD1 Glu266Lys and NOD2 (Arg702Trp and Gly908Arg) gene polymorphisms among patients with GBS.

MATERIALS AND METHOD

Polymorphisms in NOD-1 (Glu266Lys) and NOD-2 (Arg702Trp and Gly908Arg) genes were studied using polymerase chain reaction-restriction fragment length polymorphism in 105 patients with GBS and 100 healthy controls.

RESULTS

Homozygous genotype (Lys/Lys) of NOD1 was significantly associated with GBS (p=0.013); and its subtypes viz. acute motor axonal neuropathy (AMAN) and acute inflammatory demyelinating polyneuropathy (AIDP) (p=0.008 and p=0.024 respectively) than controls. In NOD2 (Arg702Trp and Gly908Arg) polymorphisms, only heterozygous genotype (Arg/Trp and Gly/Arg) showed significant association with GBS (p=0.001 and p=0.01 respectively); subtypes AMAN, acute motor-sensory axonal neuropathy (AMSAN) and AIDP showed association with heterozygote Arg702Trp (p=0.001; p=0.029 and p=0.001 respectively) whereas only AIDP was associated with heterozygote genotype Gly908Arg (p=0.003).

CONCLUSION

NOD1 (Glu266Lys) and NOD2 (Arg702Trp and Gly908Arg) polymorphisms were associated with an increased susceptibility to GBS. These polymorphisms could be genetic marker to GBS susceptibility.

Booster influenza vaccination does not improve immune response in adult inflammatory bowel disease patients treated with immunosuppressives: a randomized controlled trial

BACKGROUND

This research was conducted is to assess the effect of booster doses of the trivalent influenza vaccine in adult inflammatory bowel disease (IBD) patients treated with anti-tumor necrosis factor (TNF)-α agents and/or immunomodulators.

METHODS

Adult IBD patients and healthy individuals were subcutaneously administered the trivalent influenza vaccine. They were randomized into two groups: the single vaccination group and the two vaccination booster group. Blood samples were collected, and the antibody titers against each influenza strain were determined by hemagglutination inhibition at 3 different time points (pre-vaccination, 3 weeks post-vaccination, and after the flu season) in the single vaccination group and at 4 time points (pre-vaccination, 3 weeks post-first vaccination, 3 weeks post-second vaccination, and after the flu season) in the booster vaccination group.

RESULTS

Seventy-eight IBD patients and 11 healthy controls were randomized into the single vaccination group and the booster vaccination group. Twenty-nine patients received immunomodulators; 21 received anti-TNF-α agents; and 28 received a combination of both. No significant differences were observed in the evaluated immune response parameters between 3 weeks post-vaccination in the single vaccination group and 3 weeks post-second vaccination in the booster vaccination group (geometric mean titers: H1N1, p = 0.09; H3N2: p = 0.99; B: p = 0.94). A higher pre-vaccination titer was significantly associated with sufficient seroprotection rate after vaccination for the H1N1 strain (odds ratio 11.93, p = 0.03).

CONCLUSIONS

The second booster of trivalent influenza vaccination did not improve the immune response in adult IBD patients who were treated with immunomodulators and/or anti-TNF-α agents.

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.

Autoinflammatory granulomatous diseases: from Blau syndrome and early-onset sarcoidosis to NOD2-mediated disease and Crohn's disease

The recent identification of genetic mutations leading to dysfunction of inflammatory and apoptotic pathways, has allowed to characterise a group of diseases, recognised as monogenic autoinflammatory syndromes. Among those, Blau syndrome (BS) and early-onset sarcoidosis (EOS) have been identified as familial and sporadic phenotypes of the same non-caseating granulomatous form. Both the diseases are caused by mutations in the CARD15/NOD2 gene, encoding the cytosolic NOD2 protein, one of the key molecules in the regulation of innate immunity. Clinical onset is typically located in the first years of life and phenotype is characterised by simultaneous or less articular, cutaneous and ocular non-caseating granulomatous inflammation, which can be variably associated with a heterogeneous systemic spectrum. The CARD15/NOD2 gene has also been identified as one of the genes linked to susceptibility to Crohn's disease (CD), a common polygenic inflammatory granulomatous bowel disease. The heightened nuclear factor-κB activity, found in the intestinal tissue of patients affected by CD, has probably a genetic cause related to several CARD15/NOD2 polymorphisms. Other substitutions in the CARD15/NOD2 gene have also been found in a recently described disorder, called NOD2-associated autoinflammatory disease, which shares several clinical characteristics with BS and EOS. This review attempts to describe these diseases on the basis of the most recent evidences. We described genetic and clinical aspects, mainly focusing on BS and EOS, the most representative diseases of autoinflammatory granulomatous diseases, with the ultimate purpose to expand their knowledge.

Oral Manifestations of Crohn's Disease: A Case Report and Review of the Literature

Crohn's disease (CD) is an inflammatory disorder of the gastrointestinal tract that is likely caused by an inappropriate mucosal inflammatory response to intestinal bacteria in a genetically predisposed host. The lesions of CD can involve any region of the GI tract as well as extraintestinal sites such as the skin, joints, and eyes. The most common presenting symptoms are abdominal pain and prolonged diarrhea associated with fevers, fatigue, and malaise. Delayed growth and failure to thrive may also be observed in pediatric patients. Oral manifestations of CD are known as oral CD and may precede GI involvement, thus serving as early markers of this condition. We describe a 6-year-old male who presented with oral lesions as his initial manifestation of disease and review the current literature pertaining to oral CD.

Large germline deletions of the CYLD gene in patients with Brooke-Spiegler syndrome and multiple familial trichoepithelioma

Brooke-Spiegler syndrome (BSS) and its phenotypic variants, multiple familial trichoepithelioma (MFT) and familial cylindromatosis, are rare autosomal dominant hereditary diseases. They are characterized by the presence of multiple adnexal tumors, especially cylindromas, spiradenomas, spiradenocylindromas, and trichoepitheliomas. Implicated in the pathogenesis of the disease is the gene CYLD, which is localized on the long arm of chromosome 16. This gene encodes an evolutionarily conserved protein belonging to the deubiquitinating enzymes family, which plays a key role in many signaling pathways, especially in NF-κB, JNK, and Wnt. Less than 90 germline mutations of CYLD have been identified in patients with BSS/MFT. These mutations are mostly small alterations in the coding sequence and at exon-intron junction sites. One patient with an intronic mutation and another with a large CYLD deletion have also been recorded. In this study, the authors have analyzed a cohort of 14 patients with BSS/MFT from 13 families for large genome rearrangements by array comparative genome hybridization followed by confirmatory sequencing. We identified 2 large deletions, namely c.-34111_*297858del378779 and c.914-6398_1769del13642ins20 in patients with MFT and BSS, respectively. All other analyzable patients did not reveal any copy number alteration. It is concluded that the large rearrangements are relatively rare in patients without a germline CYLD mutation demonstrable by conventional sequencing. The pathogenetic mechanisms in patients with BSS/MFT lacking germline sequence alterations or large rearrangements in the CYLD gene remain to be clarified.

Microbiota activation and regulation of innate and adaptive immunity

The human host has coevolved with the collective of bacteria species, termed microbiota, in a complex fashion that affects both innate and adaptive immunity. Differential regulation of regulatory T-cell and effector T-cell responses are a direct result of specific microbial species present within the gut, and this relationship is subject to dysregulation during inflammation and disease. The microbiota varies widely between individuals and has a profound effect on how one reacts to various environmental stimuli, particularly if a person is genetically predisposed to an immune-mediated inflammatory disorder such as inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). Approximately, half of all CD patients have elevated antibodies to CBir1, a microbiota flagellin common to mice and humans, demonstrating flagellins as immunodominant antigens in the intestines. This review focuses on the use of flagellins as probes to study microbiota-specific responses in the context of health and disease as well as probes of innate and adaptive responses employed by the host to deal with the overwhelming bacterial presence of the microbiota.

CARD15 Gene 3020insC Mutation with Inflammatory Bowel Diseases Patients in the Black Sea Region of Turkey

BACKGROUND: The role of the CARD15 gene 3020insC frameshift mutation in the pathogenesis of inflammatory bowel diseases (IBD) investigated without a definitive conclusion. The incidence of this mutation in Turkish patients with Crohn’s disease is not known.OBJECTIVE: We investigated whether the CARD15/NOD2 3020insC frameshift mutation is a risk factor for patients with inflammatory bowel disease in Black Sea Region population in Turkey.METHODS: We studied 3020insC mutation of CARD15/NOD2 gene by allele-specific multiplex PCR in 69 patients with IBD (18 Crohn’s disease [CD] and 51 ulcerative colitis [UC]) and 101 ethnically matched healthy controls.RESULTS: CARD15/NOD2 3020insC frameshift mutation was positive in 7/18 (38.8 %), 13/51 (25.5 %), and 4/101 (4 %) of CD, UC, and healthy control groups, respectively. None of the controls or patients with Crohn’s disease and ulcerative colitis was homozygous for this mutations.CONCLUSION: This study is to investigate a relation between CARD15/NOD2 3020insC frameshift mutation and in patients with IBD in the Turkish Population. C-insertion frameshift mutation is a major contributor to the susceptibility to both CD and UC, but it is not specific to patients with CD in Turkish population.

Musculoskeletal manifestations in inflammatory bowel disease: a revisit in search of immunopathophysiological mechanisms

Inflammatory bowel diseases are chronic inflammatory disorders of multiple organ systems, primarily involving the gut, with chronic relapsing and remitting course. Musculoskeletal involvement is the most common extraintestinal manifestation. Distinct cell-mediated and humoral immunopathophysiological mechanisms have been identified underlying gut and joint inflammation in patients with inflammatory bowel disease and arthritis. Genetic polymorphisms in genes coding for NOD2 and IL12/IL23 complex lead to impaired antigenic handling in the gut and local immune dysregulation. The gut-synovial axis hypothesis implicates both environmental and host factors acting as triggers to initiate inflammation in genetically predisposed individuals, leading to priming of Th1 and Th17 lymphocytes in the gut and subsequent homing to the synovial tissue. Similar to gut, antibody-dependent cell-mediated cytotoxicity and complement-mediated cell lysis may also contribute to the joint damage. Involvement of peripheral joints occurs in 2 distinct manners, one being oligoarticular asymmetric arthritis associated with active disease and the other being polyarticular symmetric involvement of small joints. The axial involvement may include asymptomatic sacroiliitis, inflammatory back pain, and ankylosing spondylitis, running an independent clinical course. Noninflammatory involvement of the musculoskeletal system may present as osteopenia, osteonecrosis, fibromyalgia, or myopathies, leading to significant impact on quality of life.

NOD2 regulates CXCR3-dependent CD8+ T cell accumulation in intestinal tissues with acute injury

Polymorphisms in NOD2 confer risk for Crohn's disease, characterized by intestinal inflammation. How NOD2 regulates both inflammatory and regulatory intestinal T cells, which are critical to intestinal immune homeostasis, is not well understood. Anti-CD3 mAb administration is used as therapy in human autoimmune diseases, as well as a model of transient intestinal injury. The stages of T cell activation, intestinal injury, and subsequent T tolerance are dependent on migration of T cells into the small intestinal (SI) lamina propria. Upon anti-CD3 mAb treatment of mice, we found that NOD2 was required for optimal small intestinal IL-10 production, in particular from CD8(+) T cells. This requirement was associated with a critical role for NOD2 in SI CD8(+) T cell accumulation and induction of the CXCR3 ligands CXCL9 and CXCL10, which regulate T cell migration. NOD2 was required in both the hematopoietic and nonhematopoietic compartments for optimal expression of CXCR3 ligands in intestinal tissues. NOD2 synergized with IFN-γ to induce CXCL9 and CXCL10 secretion in dendritic cells, macrophages, and intestinal stromal cells in vitro. Consistent with the in vitro studies, during anti-CD3 mAb treatment in vivo, CXCR3 blockade, CD8(+) T cell depletion, or IFN-γ neutralization each inhibited SI CD8(+) T cell recruitment, and reduced chemokine expression and IL-10 expression. Thus, NOD2 synergizes with IFN-γ to promote CXCL9 and CXCL10 expression, thereby amplifying CXCR3-dependent SI CD8(+) T cell migration during T cell activation, which, in turn, contributes to induction of both inflammatory and regulatory T cell outcomes in the intestinal environment.

Infliximab and/or immunomodulators inhibit immune responses to trivalent influenza vaccination in adults with inflammatory bowel disease

BACKGROUND AND AIMS

Appropriate influenza vaccination is important for patients with inflammatory bowel disease under immunosuppressive therapy. The purpose of this study was to evaluate the influence of immunosuppressive therapy on the immune response to the trivalent influenza vaccine in adult patients with inflammatory bowel disease.

METHODS

In this cohort study, 91 participants received a single dose of influenza vaccine for the 2010/2011 season. Serum samples were collected at 3 different times (pre-vaccination, 3 weeks post-vaccination, and after flu season) to measure hemagglutination inhibition antibody titers. Immune responses were compared based on immunosuppressive therapy.

RESULTS

Among the 88 subjects who completed the study, the influenza vaccine induced a more than 4-fold increase in the mean antibody level for all flu strains. The overall seroprotection proportion (post-vaccination titer ≥ 1:40) was 81% for H1N1, 61% for H3N2, and 86% for B. Treatment with an immunomodulator reduced the immune response to the H1N1 strain (OR=0.20, p=0.01), and treatment with infliximab reduced the immune response to the other strains (H3N2 strain: OR=0.37, p=0.02; B strain: OR=0.18, p=0.03). Combination therapy with azathioprine/6-mercaptopurine and infliximab significantly inhibited the immune response to H1N1 (OR=0.056, p=0.02).

CONCLUSIONS

Infliximab and/or immunomodulators inhibit immune responses to some strains of trivalent influenza vaccination in adults with inflammatory bowel disease. For optimization of the trivalent influenza vaccination for patients with adult inflammatory bowel disease treated with immunosuppressive agents, establishing an effective vaccination method is crucial.

Dendritic cells in IBD pathogenesis: an area of therapeutic opportunity?

Dysfunction of the mucosal immune system plays an important role in inflammatory bowel disease (IBD) pathogenesis. Dendritic cells are emerging as central players based on both our increasing understanding of how genetic susceptibility impacts the mucosal immune system and the key role of dendritic cells in regulating response to gut microflora. We discuss areas of therapeutic opportunity in this evolving landscape. © 2013 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Inflammatory bowel disease: Pathogenesis

Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is characterized by chronic relapsing intestinal inflammation. It has been a worldwide health-care problem with a continually increasing incidence. It is thought that IBD results from an aberrant and continuing immune response to the microbes in the gut, catalyzed by the genetic susceptibility of the individual. Although the etiology of IBD remains largely unknown, it involves a complex interaction between the genetic, environmental or microbial factors and the immune responses. Of the four components of IBD pathogenesis, most rapid progress has been made in the genetic study of gut inflammation. The latest internationally collaborative studies have ascertained 163 susceptibility gene loci for IBD. The genes implicated in childhood-onset and adult-onset IBD overlap, suggesting similar genetic predispositions. However, the fact that genetic factors account for only a portion of overall disease variance indicates that microbial and environmental factors may interact with genetic elements in the pathogenesis of IBD. Meanwhile, the adaptive immune response has been classically considered to play a major role in the pathogenesis of IBD, as new studies in immunology and genetics have clarified that the innate immune response maintains the same importance in inducing gut inflammation. Recent progress in understanding IBD pathogenesis sheds lights on relevant disease mechanisms, including the innate and adaptive immunity, and the interactions between genetic factors and microbial and environmental cues. In this review, we provide an update on the major advances that have occurred in above areas.

NOD2/CARD15 single nucleotide polymorphism 13 (3020insC) is associated with risk of sepsis and single nucleotide polymorphism 8 (2104C>T) with herpes viruses reactivation in patients after allogeneic hematopoietic stem cell transplantation

Three NOD2 polymorphisms (single nucleotide polymorphism [SNP]8 [2104C>T, Arg702Trp], SNP12 [2722G>C, Gly908Arg], and SNP13 [3020insC, Leu1007 fsins C]), identified as disease-associated variants in Crohn's disease, have recently been suggested as gene markers of the outcome of hematopoietic stem cell transplantation (HSCT). In the present multicenter study of 464 donor-recipient pairs, we focused on the effect of NOD2 mutation(s) on the risk of infections and acute graft-versus-host disease (aGVHD). The presence of SNP13 in recipients, donors, or both was more frequently seen in patients having sepsis than in those lacking sepsis (9 of 48 versus 33 of 386, P = .046). The presence of SNP8 (recipient and/or donor positive) was associated with a higher rate of Herpes viruses reactivation (17 of 21 versus 86 of 173, P = .007). In the SNP8-positive group, a trend for a higher rate of bacteremia well controlled by antibiotics was found (9 of 10 versus 47 of 81, P = .106). In contrast, the presence of SNP13 in recipient and/or donor resulted in a poor response to antibiotics (5 of 11 versus 9 of 10, P = .042). A statistically significant association between the presence of NOD2 SNPs and acute grade > II GVHD was found in a subgroup of HSCT patients who received transplants from unrelated donors with a myeloablative conditioning regimen that included antithymocyte globulin (ATG). In this subgroup of patients, donor positivity for any SNPs investigated (7 of 18 versus 17 of 113, P = .036) and, independently, only the presence of SNP8 (4 of 8 versus 20 of 123, P = .055) were associated with severe grade ≥ II aGVHD. In conclusion, SNP8 positivity in donors or recipients makes patients more prone to Herpes viruses reactivation and bacteremia but not to sepsis. Septic complications were associated with SNP13 polymorphism. SNP8 in donors constitutes a risk factor of severe aGVHD, but only if patients received transplants from unrelated donors and received ATG as part of a conditioning regimen.

The role of NOD2 in murine and human melioidosis

Nucleotide-binding oligomerization domain 2 (NOD2) is a cytosolic pathogen recognition receptor that regulates susceptibility to a variety of infections and chronic diseases. Burkholderia pseudomallei, a facultative intracellular bacterium, causes the tropical infection melioidosis. We hypothesized that NOD2 may participate in host defense in melioidosis. We performed a series of in vitro assays and in vivo experiments and analyzed the association of human genetic variation with infection to delineate the contribution of NOD2 to the host response to B. pseudomallei. We found that transfection with NOD2 mediated NF-κB activation induced by B. pseudomallei stimulation of HEK293 cells. After low-dose inoculation with aerosolized B. pseudomallei, Nod2-deficient mice showed impaired clinical responses and permitted greater bacterial replication in the lung and dissemination to the spleen compared with wild-type mice. IL-6 and KC levels were higher in the lungs of Nod2-deficient mice. In a cohort of 1562 Thai subjects, a common genetic polymorphism in the NOD2 region, rs7194886, was associated with melioidosis, and this effect was most pronounced in women. rs7194886 was not associated with differences in cytokine production induced by whole-blood stimulation with the NOD2 ligand, muramyl dipeptide, or B. pseudomallei. To our knowledge, these findings are the first to characterize the role of NOD2 in host defense in mammalian melioidosis.

NOD2 deletion promotes cardiac hypertrophy and fibrosis induced by pressure overload

Nucleotide-binding oligomerization domain-2 (NOD2, also designated CARD15), a member of the NOD-leucine-rich repeat (LRR) protein family (also called the CATERPILLAR family), is upregulated in atheroma lesions and has an important role in regulating the intracellular recognition of bacterial components by immune cells. However, the effect of NOD2 on cardiac hypertrophy induced by a pathological stimulus has not been determined. Here, we investigated the effects of NOD2 deficiency on cardiac hypertrophy induced by aortic banding (AB) in mice. Cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. NOD2 expression was upregulated in cardiomyocytes after aortic banding surgery in wild-type (WT) mice. NOD2 deficiency promoted cardiac hypertrophy and fibrosis 4 weeks after AB. Further, the enhanced activation of TLR4 and the MAPKs, NF-κB and TGF-β/Smad pathways were found in NOD2-knockout (KO) mice compared with WT mice. Our results suggest that NOD2 attenuates cardiac hypertrophy and fibrosis via regulation of multiple pathways.

Innate and adaptive immunity in inflammatory bowel disease

Inflammatory bowel disease (IBD) includes Crohn's disease (CD) and ulcerative colitis (UC). The exact cause of IBD remains unknown. Available evidence suggests that an abnormal immune response against the microorganisms of the intestinal flora is responsible for the disease in genetically susceptible individuals. The adaptive immune response has classically been considered to play a major role in the pathogenesis of IBD. However, recent advances in immunology and genetics have clarified that the innate immune response is equally as important in inducing gut inflammation in these patients. In particular, an altered epithelial barrier function contributes to intestinal inflammation in patients with UC, while aberrant innate immune responses, such as antimicrobial peptide production, innate microbial sensing and autophagy are particularly associated to CD pathogenesis. On the other hand, besides T helper cell type (Th)1 and Th2 immune responses, other subsets of T cells, namely Th17 and regulatory T (Treg) cells, are likely to play a role in IBD. However, given the complexity and probably the redundancy of pathways leading to IBD lesions, and the fact that Th17 cells may also have protective functions, neutralization of IL-17A failed to induce any improvement in CD. Studying the interactions between various constituents of the innate and adaptive immune systems will certainly open new horizons in the knowledge about the immunologic mechanisms implicated in gut inflammation.

Single nucleotide polymorphisms in pathogen recognition receptor genes are associated with susceptibility to meningococcal meningitis in a pediatric cohort

Bacterial meningitis (BM) is a serious infection of the central nervous system, frequently occurring in childhood and often resulting in hearing loss, learning disabilities, and encephalopathy. Previous studies showed that genetic variation in innate immune response genes affects susceptibility, severity, and outcome of BM. The aim of this study is to describe whether single nucleotide polymorphisms (SNPs) in pathogen recognition gene products are associated with susceptibility to develop BM in single genes analysis as well as SNP combinations. Genotype frequencies of seven SNPs, in five immune response genes encoding for Toll-like receptors (TLRs), nucleotide oligomerization domain (NOD) proteins and caspase-1 (CASP1), in 391 children with meningococcal meningitis (MM) and 82 children with pneumococcal meningitis were compared with a large cohort of 1141 ethnically matched healthy controls. Carriage of TLR4 +896 GG mutant predisposed to susceptibility to develop MM (p = 1.2*10⁻⁵, OR  = 9.4, 95% CI  = 3.0–29.2). The NOD2 SNP8 mutant was significantly more frequent in MM patients compared to controls (p = 0.0004, OR  = 12.2, 95% CI  = 2.6–57.8). Combined carriage of TLR2 +2477 and TLR4 +896 mutants was strongly associated with MM (p = 4.2*10⁻⁵, OR  = 8.6, 95% CI  = 2.7–27.3). A carrier trait of TLR4 +896 and NOD2 SNP8 mutants was also strongly associated with susceptibility to develop MM (p = 4.2*10⁻⁵, OR  = 10.6, 95% CI  = 2.9–38.6). This study associates SNPs in TLR4 and NOD2 with susceptibility to develop MM.

Nucleotide oligomerization domain 2 polymorphisms in patients with intestinal failure

BACKGROUND

Nucleotide oligomerization domain 2 (NOD2) has been associated with intestinal immunity after the discovery that its polymorphisms are linked to Crohn's disease (CD). Intestinal failure (IF) represents a wider spectrum of diseases where intestinal homeostasis has been disrupted.

AIM

To evaluate the prevalence of NOD2 mutations in a population with IF as well as its association with the different conditions causing this problem.

METHODS

One hundred ninety-two consecutive patients with IF and 103 healthy controls were genotyped for the three most common NOD2 polymorphisms. Genotypes were compared between the groups and were related to the entities causing IF.

RESULTS

A high percentage (26%) of patients had at least one of the three most common NOD2 polymorphisms, while only a 4.8% of healthy controls had a mutant genotype. In patients with IF, specific mutations for the 702W, 908R and 1007fs alleles were 11, 5 and 12.5%, respectively, compared with 0.9% (P = 0.0003), 1.9% (P = 0.1) and 1.9% (P = 0.001) in the control group. If we consider patients with any cause of IF other than CD, the percentage is still as high as 18.8%, with specific mutation frequencies of 7.6% (702W; P = 0.01), 5.8% (908R; P = 0.1) and 8.2% (1007fs; P = 0.002). We could not establish an association between a NOD2 mutant genotype with any other specific clinical condition other than CD.

CONCLUSION

Our finding supports the importance of NOD2 in the maintenance of intestinal immune homeostasis and may be important to a variety of intestinal stressors.

Nod2-induced autocrine interleukin-1 alters signaling by ERK and p38 to differentially regulate secretion of inflammatory cytokines

BACKGROUND & AIMS

Stimulation of nucleotide-binding oligomerization domain-containing (Nod)2 and other pattern recognition receptors (PRR) in human monocyte-derived macrophages induces interleukin (IL)-1, which increases mitogen-activated protein kinase (MAPK) activation and cytokine secretion. Activation of MAPK by PRR has varied effects on inflammatory cytokine secretion. We investigated whether different levels of autocrine IL-1 mediate these varied effects.

METHODS

Macrophage responses to PRR ligands were analyzed by enzyme-linked immunosorbent assay and flow cytometry. We overexpressed or reduced MAPK levels (using small inhibitory RNA).

RESULTS

Nod2 and other PRR activated signaling via extracellular signal-related kinase (ERK) and p38 that inhibited inflammatory cytokine production by human monocyte-derived macrophages; autocrine IL-1 production prevented this inhibition. ERK and p38 inhibited inflammatory cytokine production by human macrophages that produce low levels of IL-1 (such as M2, endotoxin-tolerant, and intestinal macrophages); adding exogenous IL-1 caused ERK and p38 to stimulate production of inflammatory cytokines in these cells. In mouse macrophages, which do not produce IL-1 in response to PRR stimulation alone, addition of exogenous IL-1 reversed the ERK-mediated inhibition of IL-12p40. Increasing activation of c-Jun N-terminal kinase in Nod2-stimulated human monocyte-derived macrophages, in the absence of autocrine IL-1 signaling, caused ERK and p38 to stimulate inflammatory cytokines secretion. Importantly, infection of human intestinal macrophages with pathogens that induce IL-1 production reversed the inhibition of inflammatory cytokine production by ERK and p38.

CONCLUSIONS

In response to PRR stimulation of macrophages, the level of MAPK signaling is regulated by autocrine IL-1 and determines whether production of inflammatory cytokines is inhibited or stimulated. This mechanism could account for reported differences in MAPK regulation of inflammatory cytokines and propagate the inflammatory response to pathogens.

A dual role for receptor-interacting protein kinase 2 (RIP2) kinase activity in nucleotide-binding oligomerization domain 2 (NOD2)-dependent autophagy

Autophagy is triggered by the intracellular bacterial sensor NOD2 (nucleotide-binding, oligomerization domain 2) as an anti-bacterial response. Defects in autophagy have been implicated in Crohn's disease susceptibility. The molecular mechanisms of activation and regulation of this process by NOD2 are not well understood, with recent studies reporting conflicting requirements for RIP2 (receptor-interacting protein kinase 2) in autophagy induction. We examined the requirement of NOD2 signaling mediated by RIP2 for anti-bacterial autophagy induction and clearance of Salmonella typhimurium in the intestinal epithelial cell line HCT116. Our data demonstrate that NOD2 stimulates autophagy in a process dependent on RIP2 tyrosine kinase activity. Autophagy induction requires the activity of the mitogen-activated protein kinases MEKK4 and p38 but is independent of NFκB signaling. Activation of autophagy was inhibited by a PP2A phosphatase complex, which interacts with both NOD2 and RIP2. PP2A phosphatase activity inhibited NOD2-dependent autophagy but not activation of NFκB or p38. Upon stimulation of NOD2, the phosphatase activity of the PP2A complex is inhibited through tyrosine phosphorylation of the catalytic subunit in a process dependent on RIP2 activity. These findings demonstrate that RIP2 tyrosine kinase activity is not only required for NOD2-dependent autophagy but plays a dual role in this process. RIP2 both sends a positive autophagy signal through activation of p38 MAPK and relieves repression of autophagy mediated by the phosphatase PP2A.

Macrophage-stimulating protein polymorphism rs3197999 is associated with a gain of function: implications for inflammatory bowel disease

Crohn's disease and ulcerative colitis, the two main types of inflammatory bowel disease (IBD), were reported to be associated with a variety of genetic polymorphisms. A subset of these polymorphisms was identified in both diseases and only three of them were found in primary sclerosing cholangitis (PSC). rs3197999 (Arg689Cys) located in the MST1 gene is one of the most convincingly replicated IBD/PSC-associated polymorphisms but its functional consequences have not been investigated, yet. We expressed both MST1 gene variants (Arg(689) (MSP(wt)) and Cys(689) (MSP(mut)) in a eukaryotic cell system and compared their stimulatory effects on macrophage-like THP-1 cells. Except for the rate of apoptosis that remained unchanged, MSP(mut) significantly increased the stimulatory effect of MSP (macrophage-stimulating protein) on chemotaxis and proliferation by THP-1 cells, indicating a gain of function associated with the Arg689Cys exchange. A broad set of evidence reported previously suggests that pro-inflammatory changes in macrophage function have a major role in the initiation of the inflammatory process in IBD and PSC. Therefore, the gain of function observed with rs3197999 in MST1 might provide a cellular mechanism for the consistent association of this polymorphism with an increased risk for IBD and PSC.

The nucleotide synthesis enzyme CAD inhibits NOD2 antibacterial function in human intestinal epithelial cells

BACKGROUND & AIMS

Polymorphisms that reduce the function of nucleotide-binding oligomerization domain (NOD)2, a bacterial sensor, have been associated with Crohn's disease (CD). No proteins that regulate NOD2 activity have been identified as selective pharmacologic targets. We sought to discover regulators of NOD2 that might be pharmacologic targets for CD therapies.

METHODS

Carbamoyl phosphate synthetase/aspartate transcarbamylase/dihydroorotase (CAD) is an enzyme required for de novo pyrimidine nucleotide synthesis; it was identified as a NOD2-interacting protein by immunoprecipitation-coupled mass spectrometry. CAD expression was assessed in colon tissues from individuals with and without inflammatory bowel disease by immunohistochemistry. The interaction between CAD and NOD2 was assessed in human HCT116 intestinal epithelial cells by immunoprecipitation, immunoblot, reporter gene, and gentamicin protection assays. We also analyzed human cell lines that express variants of NOD2 and the effects of RNA interference, overexpression and CAD inhibitors.

RESULTS

CAD was identified as a NOD2-interacting protein expressed at increased levels in the intestinal epithelium of patients with CD compared with controls. Overexpression of CAD inhibited NOD2-dependent activation of nuclear factor κB and p38 mitogen-activated protein kinase, as well as intracellular killing of Salmonella. Reduction of CAD expression or administration of CAD inhibitors increased NOD2-dependent signaling and antibacterial functions of NOD2 variants that are and are not associated with CD.

CONCLUSIONS

The nucleotide synthesis enzyme CAD is a negative regulator of NOD2. The antibacterial function of NOD2 variants that have been associated with CD increased in response to pharmacologic inhibition of CAD. CAD is a potential therapeutic target for CD.

Polymorphisms in Toll-like receptors 2, 4, and 9 are highly associated with hearing loss in survivors of bacterial meningitis

Genetic variation in innate immune response genes contributes to inter-individual differences in disease manifestation and degree of complications upon infection. We recently described an association of single nucleotide polymorphisms (SNPs) in TLR9 with susceptibility to meningococcal meningitis (MM). In this study, we investigate the association of SNPs in multiple pathogen recognition and immune response genes with clinical features that determine severity and outcome (especially hearing loss) of childhood MM and pneumococcal meningitis (PM). Eleven SNPs in seven genes (TLR2, TLR4, TLR9, NOD1, NOD2, CASP1, and TRAIL) were genotyped in 393 survivors of childhood bacterial meningitis (BM) (327 MM patients and 66 PM patients). Genotype distributions of single SNPs and combination of SNPs were compared between thirteen clinical characteristics associated with severity of BM. After correction for multiple testing, TLR4+896 mutant alleles were highly associated with post-meningitis hearing loss, especially MM (p= 0.001, OR 4.0 for BM, p= 0.0004, OR 6.2 for MM). In a multigene analysis, combined carriership of the TLR2+2477 wild type (WT) with TLR4+896 mutant alleles increases the risk of hearing loss (p<0.0001, OR 5.7 in BM and p= 0.0001, OR 7.6 in MM). Carriage of one or both mutant alleles in TLR4+896 and TLR9 -1237 increases the risk for hearing loss (p = 0.0006, OR 4.1 in BM). SNPs in immune response genes contribute to differences in clinical severity and outcome of BM. The TLR system seems to play an important role in the immune response to BM and subsequent neuronal damage as well as in cochlear inflammation. Genetic markers may be used for identification of high-risk patients by creating prediction rules for post-meningitis hearing loss and other sequelae, and provide more insight in the complex immune response in the CNS possibly resulting in new therapeutic interventions.

Prevalence of genetic variants associated with inflammatory bowel disease in a healthy First Nations cohort

BACKGROUND

Inflammatory bowel disease is the result of both genes and environment. Canadian First Nations people, despite living in a region with a high prevalence of inflammatory bowel disease, are relatively protected from this disease. We aimed to compare the carriage of genetic variants associated with inflammatory bowel disease in healthy First Nations and white people.

METHODS

DNA was extracted from the venous blood of healthy First Nations (n = 340) and white (n = 285) participants from Manitoba. Genotyping was performed for 69 single nucleotide polymorphisms (SNPs) with known or suspected associations with inflammatory bowel disease. We compared the genotypes between groups by logistic regression, adjusting for multiple testing. We calculated a risk score for the NOD2 gene by adding the number of risk alleles at three important NOD2 SNPs (G908R, R702W and 3020insC).

RESULTS

We found genetic variation between white and First Nations participants at 45 of 69 SNPs. Notably, carriage of the ATG16L1 T300A mutation was lower in First Nations participants (p = 4.1 × 10(-30)). Cumulative carriage of important NOD2 variants was significantly lower among First Nations participants (3.9% v. 15.2%; p < 0.0001 for risk score) than among white participants. Risk variants in IL23R (p = 0.014) and IL12B (p = 1.2 × 10(-16)), among others, were more prevalent among First Nations participants than among white participants.

INTERPRETATION

The low prevalence of variants associated with bacterial processing and handling in First Nations people may explain their relative protection from inflammatory bowel disease. Increased carriage of a number of risk variants, for example in the interleukin-23/Th17 pathway, is especially intriguing given their importance in other inflammatory diseases of high incidence in First Nations populations.

Carbohydrate Elimination or Adaptation Diet for Symptoms of Intestinal Discomfort in IBD: Rationales for "Gibsons' Conundrum"

Therapeutic use of carbohydrates in inflammatory bowel diseases (IBDs) is discussed from two theoretical, apparent diametrically opposite perspectives: regular ingestion of prebiotics or withdrawal of virtually all carbohydrate components. Pathogenesis of IBD is discussed connecting microbial flora, host immunity, and genetic interactions. The best studied genetic example, NOD2 in Crohn's disease, is highlighted as a model which encompasses these interactions and has been shown to depend on butyrate for normal function. The role of these opposing concepts in management of irritable bowel syndrome (IBS) is contrasted with what is known in IBD. The conclusion reached is that, while both approaches may alleviate symptoms in both IBS and IBD, there is insufficient data yet to determine whether both approaches lead to equivalent bacterial effects in mollifying the immune system. This is particularly relevant in IBD. As such, caution is urged to use long-term carbohydrate withdrawal in IBD in remission to control IBS-like symptoms.

New pathogenic paradigms in inflammatory bowel disease

Recent progresses in basic science have opened new pathogenic scenarios in inflammatory bowel disease. The T helper cell type (Th)1/Th2 paradigm has been outdated thanks to the advances in understanding the function of Th17 cells. Innate immunity, nonimmune cells, and defective tolerogenic mechanisms play a no less crucial role than do adaptive immunity, immune cells, and hyperactivation of effector mechanisms. These new paradigms, together with the no longer "static" but "dynamic" vision of intestinal inflammation, highlight new possible therapeutic targets in inflammatory bowel disease.

Immunogenicity and safety of influenza vaccination in children with inflammatory bowel disease

BACKGROUND

Protection against vaccine-preventable diseases is important in inflammatory bowel disease (IBD) because of increased susceptibility and severity of infection with immunosuppressive therapy. However, immunosuppressive therapy may affect vaccine response. This study aimed to evaluate immunogenicity and safety of influenza vaccination in children with IBD.

METHODS

In this prospective cohort study, 60 children with IBD and 53 healthy controls had serum collected for preimmunization hemagglutination-inhibition antibody titers to the 2008 inactivated influenza vaccine components. Three to 5 weeks following vaccine [A/Brisbane/10/2007(H3N2), A/Brisbane/59/2007(H1N1), B/Florida/4/2006] administration, all participants had serum collected for postimmunization titers. A 4-fold or greater increase between pre- and postimmunization titers indicated an immunogenic response; a postimmunization titer ≥1:40 indicated serologic protection. Children with IBD were classified into immunosuppression status by therapy.

RESULTS

Seventy percent, 72%, and 53% of children with IBD mounted an immunogenic response to H3N2, H1N1, and influenza B components, respectively. Among children with IBD, serologic protection was achieved in 95%, 98%, and 85% to H3N2, H1N1, and influenza B components, respectively. For influenza B, children with IBD were less likely to mount an immunogenic response compared to controls (53% versus 81%, P = 0.0009), and immunosuppressed children with IBD were less likely to achieve serologic protection compared to nonimmunosuppressed children with IBD (79% versus 100%, P = 0.02). The majority (98%) tolerated the vaccine.

CONCLUSIONS

Although children with IBD achieve appropriate immunogenicity to influenza A, immunogenicity to influenza B appears to be diminished, especially with immunosuppressive therapy.

Functional studies on the IBD susceptibility gene IL23R implicate reduced receptor function in the protective genetic variant R381Q

Genome-wide association studies (GWAS) in several populations have demonstrated significant association of the IL23R gene with IBD (Crohn's disease (CD) and ulcerative colitis (UC)) and psoriasis, suggesting that perturbation of the IL-23 signaling pathway is relevant to the pathophysiology of these diseases. One particular variant, R381Q (rs11209026), confers strong protection against development of CD. We investigated the effects of this variant in primary T cells from healthy donors carrying IL23R(R381) and IL23R(Q381) haplotypes. Using a proprietary anti-IL23R antibody, ELISA, flow cytometry, phosphoflow and real-time RT-PCR methods, we examined IL23R expression and STAT3 phosphorylation and activation in response to IL-23. IL23R(Q381) was associated with reduced STAT3 phosphorylation upon stimulation with IL-23 and decreased number of IL-23 responsive T-cells. We also observed slightly reduced levels of proinflammatory cytokine secretion in IL23R(Q381) positive donors. Our study shows conclusively that IL23R(Q381) is a loss-of-function allele, further strengthening the implication from GWAS results that the IL-23 pathway is pathogenic in human disease. This data provides an explanation for the protective role of R381Q in CD and may lead to the development of improved therapeutics for autoimmune disorders like CD.

Selective downregulation of retinoic acid-inducible gene I within the intestinal epithelial compartment in Crohn's disease

BACKGROUND

A defective innate immune response may contribute to the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC). Employing a global gene expression analysis, this study was aimed at identifying specifically regulated genes within the epithelial compartment in inflammatory bowel disease (IBD).

METHODS

The epithelial fraction of human ileal mucosa samples from surgical specimens was obtained by laser microdissection. Gene expression was examined by global expression profiling (n = 18, Affymetrix), quantitative reverse-transcription polymerase chain reaction (RT-PCR) (n = 35), immunoblot analysis (n = 9), and immunohistochemistry (n = 25).

RESULTS

Global expression profiling revealed a pronounced downregulation of the retinoic acid-inducible gene I (RIG-I) within the epithelial layer of the ileum in patients with CD but not with UC. The downregulation of RIG-I was confirmed by quantitative RT-PCR, immunoblot analysis, and immunohistochemistry.

CONCLUSIONS

Epithelial downregulation of RIG-I, a known pattern recognition receptor for viral components, might contribute to alterations of the innate mucosal immune response, particularly in CD.

Distinct and overlapping genetic loci in Crohn's disease and ulcerative colitis: correlations with pathogenesis

BACKGROUND

A common genotypic basis for ulcerative colitis (UC) and Crohn's disease (CD) is implied by overlapping clinical characteristics, epidemiological studies, and association of genes with both UC and CD. We evaluated the overlap between CD and UC genetic loci stratified by pathogenetic pathways and by disease location.

METHODS

The allele frequencies of six UC-associated and 34 CD-associated single nucleotide polymorphisms (SNPs) were determined in a Canadian IBD cohort (n = 2374). Differences between CD, UC, colon-only CD, ileal CD, and controls were analyzed controlling for ethnicity, age of diagnosis, and gender.

RESULTS

In all, 21 of 34 CD-associated SNPs had similar allele frequencies in UC (n = 1230) and CD (n = 1144). Three of six UC-associated SNPs had significantly different frequencies in CD (n = 1144). Most of the divergence in allele frequency among CD and UC was noted in NOD2/autophagy pathway SNPs, while most SNPs with similar frequencies were in IL-22/23 Th17, adaptive immunity, and barrier pathways. Colon-only CD (n = 228) was compared with healthy controls: three of six UC SNPs (in MST1, HLA-DRA, and IL-23R) and 11 of 34 CD SNPs: in IRGM, NOD2 (rs2066845), CCNY, MST1, IL23R, PTPN22, C11orf30, ZNF365, PTPN2, PSMG1, and rs1456893 were significantly associated. In all, 29 of 34 CD SNPs had similar allele frequencies in colonic CD compared with ileal CD (n = 366). All UC SNPs had similar frequencies in UC and colonic CD.

CONCLUSIONS

Our results suggest that CD and UC share common genetic associations related to impaired adaptive immunity and diverge in pathways of foreign antigen processing. Colon-only CD overlaps extensively with UC and considerably with ileal CD.

Nod2: a key regulator linking microbiota to intestinal mucosal immunity

The human intestine harbors a large number of bacteria that are constantly interacting with the intestinal immune system, eliciting non-pathological basal level immune responses. Increasing evidence points to dysbiosis of microbiota in the intestine as an underlying factor in inflammatory bowel disease susceptibility. Loss-of-function mutations in NOD2 are among the stronger genetic factors linked to ileal Crohn's disease. Indeed, Nod2 is a key regulator of microbiota in the intestine, as microflora in the terminal ileum is dysregulated in Nod2-deficient mice. Nod2 is highly expressed in Paneth cells, which are responsible for the regulation of ileal microflora by anti-microbial compounds, and Nod2-deficient ileal intestinal epithelia are unable to kill bacteria efficiently. It is therefore likely that NOD2 mutations in Crohn's disease may increase disease susceptibility by altering interactions between ileal microbiota and mucosal immunity.