Epithelioid granulomas, pattern recognition receptors, and phenotypes of Crohn's disease

A Combination of Pathological Features Identifies Crohn's Disease in Surgical Bowel Resection Specimens

BACKGROUND

Diagnosis of Crohn's disease is challenging. This study aims to compare the histological features of Crohn's disease and non-Crohn's disease (other intestinal inflammatory diseases) in surgical specimens to identify a set of histologic features distinguishing Crohn's disease from non-Crohn's disease.

METHODS

Patients with Crohn's disease (N = 171) and patients with non-Crohn's disease (N = 215) diagnosed between 2010 and 2015 who had surgical bowel resection were identified. The frequency of histological features in surgical resection specimens was compared between these two groups.

RESULTS

Univariate analysis revealed that transmural inflammation, subserosal lymphoid aggregates, fissures or sinus-like structures, granulomas or granuloma-like nodules, abnormalities of the enteric nervous system, and mucosa structure alterations (muscularis mucosa thickening or mucosal atrophy with pseudopyloric gland metaplasia) were more frequent in Crohn's disease than non-Crohn's disease cases (p < 0.001 for all). Some of the above histologic features were further grouped as chronic inflammatory change which includes granulomas or granuloma-like nodules, lymphoid aggregates in the muscularis propria or subserosa, fissures or sinus-like structures, and architectural abnormality which is defined as the presence of abnormal enteric nervous system and/or mucosa structural alterations (muscularis mucosa thickening or mucosal atrophy with pseudopyloric gland metaplasia). A combination of transmural inflammation, chronic inflammatory change, and architectural abnormality had a sensitivity of 92.4% and a specificity of 97.7% for Crohn's disease.

CONCLUSIONS

In surgical bowel resection specimens, a combination of transmural inflammation, chronic inflammatory change, and architectural abnormality help diagnose Crohn's disease.

Upper gastrointestinal tract involvement of pediatric inflammatory bowel disease: A pathological review

Upper gastrointestinal (UGI) tract involvement of inflammatory bowel disease (IBD) is commonly seen in pediatric patients. Upper endoscopy is included in the routine workup of children with suspected IBD to enhance the diagnosis and management of these patients. Currently, childhood IBD is classified into ulcerative colitis (UC), atypical UC, Crohn’s disease (CD) and IBD unclassified. Histologic confirmation of UGI tract involvement, in particular the presence of epithelioid (non-caseating) granulomas, is helpful in confirming the diagnosis of IBD and its classification. Herein, we reviewed selected IBD-associated UGI tract manifestations in children. Lymphocytic esophagitis, seen predominantly in CD, is histologically characterized by increased intraepithelial lymphocytes (> 20 in one high-power field) in a background of mucosal injury with absence of granulocytes. Focally enhanced gastritis is a form of gastric inflammation in pediatric IBD marked by a focal lymphohistiocytic pit inflammation with or without granulocytes and plasma cells in a relatively normal background gastric mucosa. Duodenal inflammation seen in children with IBD includes cryptitis, villous flattening, increased intraepithelial lymphocytes, and lamina propria eosinophilia. Finally, epithelioid granulomas not associated with ruptured gland/crypt are a diagnostic feature of CD. The clinicopathologic correlation and differential diagnosis of each microscopic finding are discussed. Clinicians and pathologists should be cognizant of the utility and limitations of these histologic features.

Association of granulomas in mesenteric lymph nodes in Crohn's disease with younger age and transmural inflammation

BACKGROUND AND AIMS

Mesenteric lymph nodes were usually removed during bowel resection surgery for Crohn's disease (CD). Mesenteric lymph node (MLN) granuloma predicted postoperative disease recurrence in patients with CD after ileocolic resection (ICR). This study was aimed to identify factors associated with MLN granulomas in a cohort of CD patients who underwent ICR.

METHODS

The study group consisted of 18 patients with CD who underwent the index ICR between 2004 and 2012 and had MLN granulomas. The control group included 32 cases negative for MLN granulomas, which were randomly selected from the same period. Clinicodemographic and histological features were compared in these two groups.

RESULTS

The presence of MLN granuloma was associated with younger age, perianal disease, and ileocolic disease. Gender, body mass index, smoking status, disease duration, extraintestinal manifestation, length of bowel resected, total number of nodes examined, medical treatment, and indications for surgery were not significantly different between the groups. The presence of MLN granuloma was associated with mural granuloma, transmural inflammation, mural abscess, hypertrophy of the muscularis propria, fibrosis of the muscularis propria, and serosal fibrosis in the small bowel. The multivariable analysis confirms that MLN granuloma was associated with age and transmural inflammation.

CONCLUSIONS

In CD patients who underwent the index ICR, the presence of MLN granuloma was associated with younger age and transmural inflammation. Our current results suggest that the detection of MLN granulomas may be enhanced in patients at higher risk, that is, younger patients or those with transmural inflammation on imaging or histopathology.

Pathogen recognition and Toll-like receptor targeted therapeutics in innate immune cells

The innate immune system deploys a variety of pattern-recognition receptors (PRRs) which include Toll-like receptors (TLRs), RIG-I-like receptors, NOD-like receptors, and C-type lectin receptors to detect the invasion of pathogens and initiate protective responses. The intercellular and intracellular orchestration of signals from different PRRs, their endogenous or microbial ligands and accessory molecules determine the stimulatory or inhibitory responses. Progressing over the last two decades, considerable research on the molecular mechanisms underlying host-pathogen interactions has led to a paradigm shift of our understanding of TLR signaling in the innate immune system. Given that a significant amount of evidence implicates TLRs in the pathogenesis of immune diseases and cancer, and their activation occurs early in the inflammatory cascade, they are attractive targets for novel therapeutic agents. In this review, we discuss the recent advances in TLR signaling cross talks and the mechanism of pathogen recognition with special emphasis on the role of TLRs in tumor immunity and TLR-targeted therapeutics.

Identification of the distinguishing features of Crohn's disease and ischemic colitis using computed tomographic enterography

Background and aims: The differential diagnosis between Crohn’s disease (CD) and ischemic colitis (ISC) is important as their clinical management is different. ISC can easily be misdiagnosed as CD, especially in elderly populations. The distinctive radiographic features of the two disease entities have not been investigated. The aim of this study is to assess the utility of computed tomographic enterography (CTE) in the differential diagnosis between CD and ISC.

Methods: Patients with confirmed CD and ISC were identified through an electronic medical record search of the Cleveland Clinic Foundation. Patients who had undergone CTE, with or without concurrent colonoscopy and histopathological specimens, were included in this study. CTE images were blindly re-reviewed by an expert gastrointestinal radiologist. The sensitivities, specificities, accuracies and positive and negative predictive values for each of the CTE findings in differentiating CD from ISC were estimated. Kappa coefficients (κ) were calculated to measure diagnosis agreement between CTE and the reference standard.

Results: A total of 34 eligible patients were included in this study with 17 having CD and 17 having ISC. In differentiating CD from ISC, the presence of mucosal hyperenhancement and absence of the “target sign” on CTE showed a sensitivity of 100% each for CD, while the two radiographic features yielded a low specificity of 35.3% and 76.5%, respectively. The presence of stricture had a lower sensitivity of 64.7% for the detection of CD but had a high specificity of 100%. In distinguishing CD from ISC, the accuracy of presence of mucosal hyperenhancement, stricture and absence of target sign were 67.7%, 82.4% and 88.2%, respectively. The combination of the presence of mucosal hyperenhancement and the absence of the target sign achieved an accuracy of 100% for distinguishing CD from ISC. There was a good correlation between CTE and the reference standard for distinguishing CD from ISC (κ = 0.882).

Conclusions: CTE appeared to be clinically useful in distinguishing CD from ISC.

Inflammatory bowel disease in Chinese children: A retrospective analysis of 49 cases

To present study reports the clinical characteristics, diagnosis and management of pediatric patients with inflammatory bowel disease (IBD) in China. Clinical records of 49 pediatric patients with IBD at Fudan University Children's Hospital (Shanghai, China) between July 2001 and May 2012 were reviewed. Of 49 patients (30 males and 19 females), 8 patients had ulcerative colitis (UC) and 41 patients had Crohn's disease (CD). The mean age was 10.4 years in patients with UC and 10.1 years in patients with CD. The percentages of patients with UC with abdominal pain, diarrhea or rectal bleeding were 62.5, 100 and 87.5%, respectively, and that of CD patients were 75.6, 61 and 39%, respectively. Patients with UC were underweight (37.5%), and had oral ulcers (12.5%) and arthritis (12.5%), and patients with CD were underweight (34.1%), and had oral ulcers (26.8%), anal fistulas (22%) and arthritis (19.5%). Patients with CD had a higher proportion of immunoglobulin G, C-reactive protein and erythrocyte sedimentation rate compared with patients with UC. Histologic lesions of patients with UC were primarily located in the sigmoid colon (75%), transverse colon (50%) or pan-colon (50%), and in patients with CD they were located in the distal ileum (51.2%), ileocecum (58.5%) or upper gastrointestinal tract (41.5%). All patients underwent colonoscopies and 13 underwent double-balloon enteroscopies. Standard treatment for IBD, including corticosteroids, 5-aminosalicylate, and immunosuppressants (6-mercaptopurine and azathioprine), were administered to all patients. In addition 3 patients were treated with infliximab and 10 patients were treated with thalidomide. Comprehensive assessment of clinical, laboratory, endoscopic, and pathohistological data will benefit the timely diagnosis of IBD.

Pediatric Crohn's disease from onset to adulthood: granulomas are associated with an early need for immunomodulation

OBJECTIVE

Childhood onset Crohn's disease (CD) is considered more aggressive than adult onset disease. Epithelioid cell granulomas in intestinal biopsies are one, non-obligate, criterion of CD. We investigated granulomas as markers of CD severity in children followed to adulthood.

MATERIAL AND METHODS

Forty-five individuals with childhood onset CD were studied from diagnosis until attainment of final height, with data on disease location, medical and surgical management and with detailed growth data analyses. A blinded review of diagnostic biopsies was also performed.

RESULTS

We found granulomas in 22/45 (49%) children at diagnosis, altogether in 28/45 (62%) patients during the disease course (median overall follow-up - 12.3 years, range 9.3-18). Granulomas were found in 9/11 (82%) with upper gastrointestinal involvement (cumulatively 17/20, 85%) (p = 0.017 and p = 0.006, respectively). The time from diagnosis to initiating immune modulating treatment (median 4.5 months, range 0-75) was shorter in the granuloma-positive group (16/22) compared to the granuloma-negative group (18/23) (median 33 months, range 2-105; p = 0.01). The median standard deviation score height at diagnosis and final adult height (both adjusted for target height) did not correlate to findings of granulomas.

CONCLUSIONS

Epithelioid cell granulomas were associated with a shorter time to initiating immune modulating drugs, as a possible sign of more severe disease, but growth was not affected.

Polymorphisms in the sodium-dependent ascorbate transporter gene SLC23A1 are associated with susceptibility to Crohn disease

BACKGROUND

Crohn disease (CD) and ulcerative colitis (UC) are 2 common inflammatory bowel diseases (IBDs) associated with intestinal inflammation and tissue damage. Oxidative stress is suggested to play a major role in the initiation and progression of IBD. Vitamin C (ascorbate, ascorbic acid) supplementation has reduced oxidative stress in persons with IBD. The role of ascorbate transporters in IBD remains to be determined. SLC23A1 is a major ascorbate transporter in the intestinal tract, and some of its genetic variants have been associated with severely decreased ascorbate transport and lower systemic concentrations.

OBJECTIVE

This study aimed to determine whether common genetic variants in the vitamin C transporter SLC23A1 are associated with the risk of IBD.

DESIGN

Genomic DNA samples from patients with CD (n = 162) and UC (n = 149) from the Manitoba IBD Cohort Study and ethnically matched controls (n = 142) were genotyped for 3 SLC23A1 polymorphisms (rs6596473, rs33972313, and rs10063949) by using TaqMan assays.

RESULTS

Variation at rs10063949 (G allele for heterozygote and homozygote) was associated with increased susceptibility to CD (OR: 2.54; 95% CI: 1.38, 4.66; OR: 4.72; 95% CI: 2.53, 8.81; P < 0.0001; respectively). A strong linkage disequilibrium (LD) was observed across the SLC23A1 region (variation rs6596473 with rs10063949) for CD and UC (D' = 0.94 and 0.96, respectively). The risk alleles confirmed a haplotype (CGG) that is carried more in CD patients (65.3%, P < 0.0001) than in controls (43.5%).

CONCLUSIONS

A genetic variant (rs10063949-G) in the SLC23A1 ascorbate transporter locus was identified and is associated with an increased risk of CD in a white Canadian IBD cohort. The presented evidence that SLC23A1 variations can modulate the risk of CD has implications for understanding ascorbate transport in CD patients and provides a novel opportunity toward individualized nutritional therapy for patients carrying the disease-associated genotype.

Progress in histopathological diagnosis of ulcerative colitis

In recent years, the incidence of ulcerative colitis (UC) has been increasing year by year, which affect people's health and life seriously. Although UC is known as a clinical disease for more than a century, there is still a lack of specific diagnostic index for this disease. UC diagnosis is mainly based on clinical features, endoscopic findings and biopsy pathology as well as the exclusion of other diseases. Currently, histopathological diagnosis has become a research hot spot. Scholars around the world have attached great importance to the role of biopsy in the diagnosis of UC. This article will review recent progress in histopathological diagnosis of UC.

Genetic variants synthesize to produce paneth cell phenotypes that define subtypes of Crohn's disease

BACKGROUND & AIMS

Genetic susceptibility loci for Crohn's disease (CD) are numerous, complex, and likely interact with undefined components of the environment. It has been a challenge to link the effects of particular loci to phenotypes of cells associated with pathogenesis of CD, such as Paneth cells. We investigated whether specific phenotypes of Paneth cells associated with particular genetic susceptibility loci can be used to define specific subtypes of CD.

METHODS

We performed a retrospective analysis of 119 resection specimens collected from patients with CD at 2 separate medical centers. Paneth cell phenotypes were classified as normal or abnormal (with disordered, diminished, diffuse, or excluded granule phenotypes) based on lysozyme-positive secretory granule morphology. To uncover the molecular basis of the Paneth cell phenotypes, we developed methods to determine transcriptional profiles from whole-thickness and laser-capture microdissected, formalin-fixed, paraffin-embedded tissue sections.

RESULTS

The proportion of abnormal Paneth cells was associated with the number of CD-associated NOD2 risk alleles. The cumulative number of NOD2 and ATG16L1 risk alleles had an additive effect on the proportion of abnormal Paneth cells. Unsupervised clustering analysis of demographic and Paneth cell data divided patients into 2 principal subgroups, defined by high and low proportions of abnormal Paneth cells. The disordered and diffuse abnormal Paneth cell phenotypes were associated with an altered transcriptional signature of immune system activation. We observed an inverse correlation between abnormal Paneth cells and presence of granuloma. In addition, high proportions of abnormal Paneth cells were associated with shorter time to disease recurrence after surgery.

CONCLUSIONS

Histologic analysis of Paneth cell phenotypes can be used to divide patients with CD into subgroups with distinct pathognomonic and clinical features.

Characteristics and significance of colorectal cancer associated lymphoid reaction

A subset of colorectal cancers (CRCs) exhibits so-called Crohn's like lymphoid reaction (CLR), an inflammatory reaction pattern that consists of numerous transmural lymphoid aggregates. However, the composition of these aggregates, their biological mechanisms and their prognostic significance are not well-defined. We analyzed two CRC cohorts (418 and 149 patients) and determined clinicopathological features including survival. A new method for evaluating CLR based on counting the areal density of the lymphoid follicles (CLR density) was adopted. Immune cell densities at intratumoral and peritumoral regions, as well as the composition of the lymphoid follicles, were studied by immunohistochemistry. We found that CLR comprised of lymphoid aggregates with no evidence of granuloma formation. High CLR density associated with lower tumor stage, lack of preoperative radiotherapy or chemoradiotherapy and deficient mismatch repair enzyme expression. CLR density had positive correlations with peritumoral and intratumoral densities of CD83(+) mature dendritic cells and T cells. High CLR density associated with better survival and had prognostic value that was independent of stage, Klintrup-Mäkinen score for peritumoral inflammation and the numbers of tumor infiltrating T cells. CLR density evaluation had excellent intraobserver and interobserver agreement. In conclusion, the results suggest that CLR contributes to the adaptive antitumor immunity. Quantitative evaluation of CLR density is a relevant prognostic indicator in CRC.

Frequency and characteristics of granulomas in 368 pediatric patients with Crohn’s disease

Introduction: Epitheloid granulomas are one of the best histological criteria for distinguishing Crohn’s disease from other inflammatory bowel diseases. However, the role of granuloma in the pathogenesis and clinical characteristics of Crohn’s disease is unclear. Aim: The aim of the present study was to evaluate the frequency of granulomas and their association with clinical characteristics using the database of the Hungarian Pediatric Inflammatory Bowel Disease Registry. Method: Three hundred and sixty-eight children with Crohn’s disease were registered between January 1st, 2007 and December 31st, 2010. Results: The frequency of granulomas was 31.4% (111/353) at diagnosis. Isolated granuloma in the upper gastrointestinal tract was detected in 2.5% of patients, while those in the terminal ileum was found in 5% of patients. There was no difference in location, behavior and disease activity indexes between patients with and without granulomas. Need for immunomodulators and biological therapy was similar in the two groups in the first year of diagnosis. Conclusions: The frequency of granulomas in this cohort was comparable to the frequency reported in other studies. Interestingly, granulomas in the terminal ileum or upper gastrointestinal tract contributed to the diagnosis of Crohn’s disease in one of 13 children. These data indicate that multiple biopsies from multiple sites are essential for the diagnosis of pediatric Crohn’s disease. Orv. Hetil., 154 (43), 1702–1708.

Toll-like receptors and human disease: lessons from single nucleotide polymorphisms

Toll-like receptors (TLRs), a large group of proteins which recognize various pathogen-associated molecular patterns, are critical for the normal function of the innate immune system. Following their discovery many single nucleotide polymorphisms within TLRs and components of their signaling machinery have been discovered and subsequently implicated in a wide range of human diseases including atherosclerosis, sepsis, asthma, and immunodeficiency. This review discusses the effect of genetic variation on TLR function and how they may precipitate disease.

Specific antibody and interferon-gamma responses associated with immunopathological forms of bovine paratuberculosis in slaughtered Friesian cattle

Mycobacterium avium subsp. paratuberculosis (MAP) infection causes a chronic granulomatous inflammatory regional enteritis in ruminants. Cell-mediated immune responses are assumed to be protective and therefore, to be associated with its more delimited lesion types, while humoral responses are mainly associated with diffuse histopathological lesions. However, this duality of immune responses has been recently questioned. The aim of this study was to assess the relationship between both types of immunological responses and the type and extension of intestinal lesions and the presence of MAP in bovine tissues. Standard histopathological examinations, two microbiological procedures (culture and real time PCR (rtPCR)), as well as MAP specific antibody and interferon gamma (IFN-γ) release assays (IGRA) were performed on tissues and blood of 333 slaughtered Holstein-Friesian animals. Paratuberculous lesions were observed in 176 (52.9%) of the animals and overall MAP detection rates were estimated at 13.5% and 28.5% for tissue culture and rtPCR, respectively. Unlike the relatively constant non-specific IFN-γ release, both the antibody levels and the specific IFN-γ release significantly increased with tissue damage. Delimited immunopathological forms, which accounted for 93.2% of all forms, were mostly related to positive testing in the IGRA (38.4%) whereas diffuse ones (6.8%) were associated with antibody seropositivity (91.7%). However, since the frequency of positive immune responses in both tests increased as the lesions severity increased, polarization of Th1/Th2 responses was less prominent than expected. MAP was detected in the majority of ELISA-positive animals (culture+: 90%, rtPCR+: 85%) but the bacteria was only confirmed in the 36.1% of IGRA-positive animals by any of the two microbiological tests. In terms of diagnosis, the antibody test was a good indicator of advanced tissue damage (diffuse forms), but the IGRA did not associate well with more delimited forms or with MAP detection.

Microbiota separation and C-reactive protein elevation in treatment-naïve pediatric granulomatous Crohn disease

OBJECTIVES

In patients with inflammatory bowel diseases (IBDs), the presence of noncaseating mucosal granuloma is sufficient for diagnosing Crohn disease (CD) and may represent a specific immune response or microbial-host interaction. The cause of granulomas in CD is unknown and their association with the intestinal microbiota has not been addressed with high-throughput methodologies.

METHODS

The mucosal microbiota from 3 different pediatric centers was studied with 454 pyrosequencing of the bacterial 16S rRNA gene and the fungal small subunit (SSU) ribosomal region in transverse colonic biopsy specimens from 26 controls and 15 treatment-naïve pediatric CD cases. Mycobacterium avium subspecies paratuberculosis (MAP) was tested with real-time polymerase chain reaction. The correlation of granulomatous inflammation with C-reactive protein was expanded to 86 treatment-naïve CD cases.

RESULTS

The CD microbiota separated from controls by distance-based redundancy analysis (P = 0.035). Mucosal granulomata found in any portion of the intestinal tract associated with an augmented colonic bacterial microbiota divergence (P = 0.013). The granuloma-based microbiota separation persisted even when research center bias was eliminated (P = 0.04). Decreased Roseburia and Ruminococcus in granulomatous CD were important in this separation; however, principal coordinates analysis did not reveal partitioning of the groups. CRP levels >1 mg/dL predicted the presence of mucosal granulomata (odds ratio 28 [6-134.32]; 73% sensitivity, 91% specificity).

CONCLUSIONS

Granulomatous CD associates with microbiota separation and C-reactive protein elevation in treatment-naïve children; however, overall dysbiosis in pediatric CD appears rather limited. Geographical/center bias should be accounted for in future multicenter microbiota studies.

Genetic variants in autophagy-related genes and granuloma formation in a cohort of surgically treated Crohn's disease patients

BACKGROUND AND AIMS

Granulomas are a characteristic microscopic finding in Crohn's disease. Their clinical significance is controversial and their pathogenesis is unknown, but impaired processing of bacterial components has been suggested. Autophagy is a fundamental process involved in the elimination of intracellular bacteria. Genetic variants in autophagy genes IRGM and ATG16L1 have been associated with susceptibility to Crohn's disease. We therefore investigated whether variants in autophagy genes contribute to granuloma formation.

METHODS

Surgical specimens from 464 clinically well-documented Crohn's patients were reviewed and scored for the presence and distribution of granulomas. All patients were genotyped for the CD-associated SNPs in ATG16L1 and IRGM as well as for 77 haplotype tagging SNPs in 13 additional autophagy genes.

RESULTS

Granulomas were found in 75% of the patients. Their frequency increased with more distal involvement of the GI tract. Granuloma positive patients were significantly younger at the time of diagnosis and surgery, and were more likely to smoke. We identified associations between granulomas and autophagy gene variants ATG4A (rs5973822), FNBP1L (rs17109951) and ATG4D (rs7248026; rs2304165; rs10439163).

CONCLUSION

These findings suggest that granuloma formation is a marker of a more aggressive disease course, and that variants in autophagy genes ATG4A, ATG2A, FNBP1L and ATG4D, may contribute to granuloma formation.

Role of genetics in the diagnosis and prognosis of Crohn's disease

Considering epidemiological, genetic and immunological data, we can conclude that the inflammatory bowel diseases are heterogeneous disorders of multifactorial etiology in which hereditability and environment interact to produce the disease. It is probable that patients have a genetic predisposition for the development of the disease coupled with disturbances in immunoregulation. Several genes have been so far related to the diagnosis of Crohn's disease. Those genes are related to innate pattern recognition receptors, to epithelial barrier homeostasis and maintenance of epithelial barrier integrity, to autophagy and to lymphocyte differentiation. So far, the most strong and replicated associations with Crohn's disease have been done with NOD2, IL23R and ATG16L1 genes. Many genes have so far been implicated in prognosis of Crohn's disease and many attempts have been made to classify genetic profiles in Crohn's disease. CARD15 seems not only a susceptibility gene, but also a disease-modifier gene for Crohn's disease. Enriching our understanding on Crohn's disease genetics is important but when combining genetic data with functional data the outcome could be of major importance to clinicians.

Role of genetics in the diagnosis and prognosis of Crohn's disease

Considering the epidemiological, genetic and immunological data, we can conclude that the inflammatory bowel diseases are heterogeneous disorders of multifactorial etiology in which hereditability and environment interact to produce the disease. It is probable that patients have a genetic predisposition for the development of the disease coupled with disturbances in immunoregulation. Several genes have so far been related to the diagnosis of Crohn's disease. These genes are related to innate pattern recognition receptors, to epithelial barrier homeostasis and maintenance of epithelial barrier integrity, to autophagy and to lymphocyte differentiation. So far, the strongest and most replicated associations with Crohn's disease have been demonstrated with NOD2, IL23R and ATG16L1 genes. Many genes have so far been implicated in the prognosis of Crohn's disease and many attempts have been made for classification of genetic profiles in Crohn's disease. CARD15 seems to be not only a susceptibility gene, but also a disease-modifier gene for Crohn's disease. Enriching our understanding of Crohn's disease genetics is of value, but when combining genetic data with functional data the outcome could be of major importance to clinicians.

New insights into gastrointestinal and hepatic granulomatous disorders

Numerous diseases that involve the gastrointestinal tract reveal the presence of granulomas on histological analysis. Granulomatous diseases can be either primary or secondary to environmental factors. Granulomas are dynamic structures composed of organized collections of activated macrophages, including epithelioid and multinucleated giant cells, surrounded by lymphocytes. The formation of granulomas is usually in response to antigenic stimulation and is orchestrated through cytokines, immune cells and host genetics. In this Review, the pathogenesis and etiologies of granulomas of the gastrointestinal tract and liver are discussed, as are the available diagnostic tools to help differentiate their various underlying etiologies. In addition, the role of granulomas in harboring latent tuberculosis is reviewed. The effects of tumor necrosis factor antagonists and interferon-α on the development of granulomas are also discussed.

Lymphatics, tertiary lymphoid organs and the granulomas of Crohn's disease: an immunohistochemical study

BACKGROUND

Case studies in the past repeatedly suggested that the fundamental alteration in Crohn's disease occurs in the regional lymphatics of the intestine.

AIM

To evaluate the lymphatic inflammation in Crohn's disease, and to characterise lymphoid aggregates and granulomas in and surrounding lymphatics and blood vasculature.

METHODS

Forty-eight tissue blocks from 24 Crohn's disease patients and 23 tissue blocks from 23 control patients were selected. Tissue sections were immunostained with a lymphatic endothelial cell marker (D2-40), a marker for blood vasculature (FVIII), and markers for T cells (CD3), B cells (CD20) and macrophages (CD68).

RESULTS

Lymphangiectasia and lymphocytic perilymphangitis were demonstrated in all 24 patients, lymphocyte-obstructed lymphatics in seven patients, granuloma-obstructed lymphatics in nine patients and inflammatory lymphoid follicles in all 24 patients. Free-standing granulomas occurred in 19 patients, and in three further patients granulomas were in or attached to blood vascular units.

CONCLUSIONS

This study, employing immunohistochemistry, revealed, better than standard microscopy, the association of inflammation, granulomas and tertiary lymphoid follicles or organs with the lymphatic vasculature in Crohn's disease. Disease in some patients was characterised by perilymphangitis and lymphoid follicular inflammation and in others by granulomas, some of which totally obstructed lymphatics. These findings have aetiological, therapeutic and prognostic implications.

Predictive value of epithelial gene expression profiles for response to infliximab in Crohn's disease

BACKGROUND

Infliximab (IFX) has become the mainstay of therapy of refractory Crohn's disease (CD). However, a subset of patients shows incomplete or no response to this agent. In this study we investigated whether we could identify a mucosal gene panel to predict (non)response to IFX in CD.

METHODS

Mucosal biopsies were obtained during endoscopy from 37 patients with active CD (19 Crohn's colitis [CDc] and 18 Crohn's ileitis [CDi]) before and after first IFX treatment. Response was defined based on endoscopic and histologic findings. Total RNA was analyzed with Affymetrix Human Genome U133 Plus 2.0 Arrays. Quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) was used to confirm microarray data.

RESULTS

At baseline, significant gene expression differences were found between CDc and CDi. For predicting response in CDc, comparative analysis of CDc pretreatment expression profiles identified 697 significant probe sets between CDc responders (n = 12) and CDc nonresponders (n = 7). Class prediction analysis of CDc top 20 and top 5 significant genes allowed complete separation between CDc responders and CDc nonresponders. The CDc top 5 genes were TNFAIP6, S100A8, IL11, G0S2, and S100A9. Only one patient with CDi completely healed the ileal mucosa. Even using less stringent response criteria, we could not identify a predictive gene panel for IFX responsiveness in CDi.

CONCLUSIONS

This study identified a 100% accurate predictive gene signature for (non)response to IFX in CDc, whereas no such a predictive gene set could be identified for CDi.

Granulomas in Crohn's disease: are newly discovered genetic variants involved?

BACKGROUND

Non-caseating granulomas exist in a substantial portion of patients with Crohn's disease (CD). Several single nucleotide polymorphisms (SNPs) have been identified as a having strong association with CD, including SNPs within the autophagy related 4 homolog A (ATG4A) gene and the neutrophil cytosolic factor 4 (NCF4) gene. We hypothesized a possible association between the presence of granulomas in CD patients and variants in the ATG4A and NCF4 genes.

AIMS

To investigate whether variants in the NCF4 and ATG4A genes are associated with granuloma formation in a cohort of Israeli patients with CD, exploring demographic and clinical characteristics that differ between granuloma positive and granuloma negative patients.

METHODS

307 Israeli patients with CD were studied. Patients with CD who underwent biopsy or resection of the intestine were classified according to presence or absence of granulomas. Using PCR-RFLP we determined the allele frequency in SNP rs4821544 (NCF4 gene) and SNP rs807185 (ATG4A gene) for all patients.

RESULTS

Granulomas were found in 85 out of 307 CD patients (27%). There were no significant differences between patients with or without granulomas in allele frequency in SNPs rs4821544 and rs807185. CD Patients with granuloma were younger at diagnosis than patients without granuloma (mean age 19 vs. 27, respectively, P<0.0001) and were more likely to undergo surgery (55.3% vs. 34.8%, respectively, P=0.002).

CONCLUSIONS

No association was found between SNPs rs4821544 and rs807185 and the presence of granulomas in CD patients. Granuloma positive patients were more likely to be younger and to undergo surgery.

Is there a role for Crohn's disease-associated autophagy genes ATG16L1 and IRGM in formation of granulomas?

OBJECTIVE

Autophagy-related 16-like 1 gene (ATG16L1) and immunity-related guanosine triphosphatase gene (IRGM) are associated with Crohn's disease susceptibility and autophagy. Elimination of invading pathogens is a function of autophagy. Formation of granulomas can be attributed to impaired recognition of bacterial components by the innate immune system. This study was undertaken to elucidate whether disease-associated variants in ATG16L1 and IRGM by affecting autophagy pathways impair pathogen clearance in the cell and thereby cause increased prevalence of granulomas in Crohn's disease patients.

METHODS

Genotypes of the inflammatory bowel disease patient cohort consisting of 819 inflammatory bowel disease patients and over 1700 histology reports on intestinal biopsies obtained during ileocolonoscopy stating the presence or absence of granulomas were included in this case-control study.

RESULTS

We confirm the association of the ATG16L1 variant and IRGM variants with Crohn's disease. Comparison of the genotype frequency of the ATG16L1 SNP (rs2241880) and the presence or absence of granuloma in 179 cases showed a P value of 0.16. Both variants in IRGM (rs4958847 and rs13361189) showed P values of 0.7 after comparison with granuloma prevalence in 213 cases. A total of 169 Crohn's disease patients were genotyped for both the genes, but no evidence for gene-gene interaction between ATG16L1 and IRGM and granuloma formation was found.

CONCLUSION

Our Crohn's disease patient cohort showed no association of the variants in ATG16L1 or IRGM and the presence of granulomas.

The V249I polymorphism of the CX3CR1 gene is associated with fibrostenotic disease behavior in patients with Crohn's disease

OBJECTIVES

CX3CR1, the receptor of CX3CL1/fractalkine, is involved in regulation of inflammatory response and the CX3CR1-I249-M280 naturally occurring mutants are associated with altered binding to the ligand. Our aim was to evaluate the frequency of CX3CR1 V249I and T280M polymorphisms and NOD2/CARD15 mutations in Crohn's disease patients and to search for a relationship with phenotype.

METHODS

Clinical data were retrospectively collected. V249I and T280M polymorphisms of CX3CR1 gene and NOD2/CARD15 mutations (R702W, G908R, 3020InsC) were identified.

RESULTS

Two hundred and thirty-nine patients (140 females, 39.7+/-14.1 years) were included. About 37.4% were heterozygous and 8.8% were homozygous for the V249I CX3CR1 polymorphism, 18.1% were heterozygous and 1.3% homozygous for the T280M CX3CR1 polymorphism and 35.9% had at least one of the three mutations of NOD2/CARD15. The T280M CX3CR1 polymorphism was not associated with any phenotype. In univariate analysis, stenosis was significantly associated with both V249I CX3CR1 polymorphism and 3020InsC NOD2/CARD15 mutations. In smoker patients carrying the CX3CR1 allele I249, there was a significant increase in the frequency of fibrostenosing disease [P=0.005, odds ratio (OR): 3.25] whereas this relationship disappeared in the group of nonsmokers (P=0.72). In multivariate analysis, 3020InsC NOD2/CARD15 mutations and the V249I CX3CR1 polymorphism were independent risk factors for intestinal stenosis (P=0.046, OR: 1.8 and P=0.044, OR: 2.4, respectively).

CONCLUSION

In Crohn's disease, V249I CX3CR1 polymorphism is associated with intestinal strictures, particularly in smokers. This association is independent of CARD15 mutations.

Frequency and clinical correlations of granulomas in children with Crohn disease

BACKGROUND

Granulomas are pathognomonic findings of Crohn disease (CD); however, their occurrence and clinical significance are not well characterized. Our aim was to determine the frequency and distribution of granulomas in untreated and treated patients with CD and their relation to age and disease severity.

PATIENTS AND METHODS

Records from patients with CD undergoing colonoscopy with terminal ileum biopsy over 7 years were reviewed. Clinical information and laboratory, pathology, and radiology results were recorded. The frequency and distribution of granulomas were determined.

RESULTS

From 376 patients with CD, 75% underwent concurrent esophagogastroduodenoscopy and colonoscopy. Of those, 65% (184/282) were untreated. Granulomas were identified in 48% (136/282) of all patients and in 61% (112/184) of untreated patients and 24.5% (24/98) of treated patients (P < 0.0005). The upper tract and terminal ileum biopsies were essential to the identification of 42% of patients with granulomas. The presence of granulomas at diagnosis was related to anti-Saccharomyces cerevisiae antibodies, hypoalbuminemia, perianal disease, and gastritis at presentation (P = 0.03, P = 0.008, P = 0.03, and P = 0.001), respectively, and to perianal disease and infliximab treatment at the latest visit (P = 0.02 and P = 0.01), respectively. Granulomas were not related to age, sex, ethnicity, weight and height z scores, hemoglobin, C-reactive protein, erythrocyte sedimentation rate, CARD15/NOD2 mutations, abdominal surgery, or stricturing or fistulizing disease.

CONCLUSIONS

Granulomas were identified in 61% of fully investigated pediatric patients with CD at diagnosis, including a substantial proportion of patients in whom colonoscopy to the cecum would have been insufficient for diagnosis. Granulomas were more frequent in untreated patients (P < 0.0005), and their prevalence was not affected by age. The presence of granulomas at diagnosis was associated with perianal disease, gastritis, hypoalbuminemia, anti-Saccharomyces cerevisiae antibodies, and infliximab treatment.

Diverse effects of the CARD15 and IBD5 loci on clinical phenotype in 630 patients with Crohn's disease

OBJECTIVES

Genetic variants at the CARD15 and IBD5 loci are strongly associated with Crohn's disease (CD), but evidence of the effect of these variants on the clinical expression of CD is conflicting and has often been hampered by small sample sizes. We studied 630 well-characterized patients to clarify the genotype/phenotype relationship in CD.

METHODS

Patients and healthy controls were genotyped for three common mutations in CARD15 and a marker of the IBD5 risk haplotype. Allele frequencies were compared between phenotypic subgroups using chi2 or Fisher's exact tests. Genotype/phenotype analysis was carried out using multinomial logistic regression modelling allowing for adjustment for correlated or confounding factors.

RESULTS

The mean age at diagnosis was significantly lower in carriers of the CARD15 or IBD5 risk alleles. After correction for age and smoking, CARD15 mutations were strongly associated with both ileal disease (P=8.8 x 10(-6)) and stenotic disease (P=0.003), but the association with stenotic disease appeared to be due to a confounding effect with ileal disease. CARD15 mutations were also associated with the presence of granulomas (P=5.7 x 10(-5)), which remained significant after adjustment for age at diagnosis and disease location (P=0.0047). The IBD5 risk haplotype frequency was significantly elevated in cases with perianal disease (P=0.028) and axial spondyloarthropathy (P=0.012).

CONCLUSION

Genetic variants at the CARD15 and IBD5 loci have diverse effects on clinical expression in CD. CARD15 mutations are significantly correlated with the presence of granulomas.

Granuloma-positive Crohn's disease

BACKGROUND

The epithelioid granuloma is a characteristic histological feature of Crohn's disease. In some pathological classification schemes, the criteria for a definite, probable or possible diagnosis have been listed, with the epithelioid granuloma indicating definite Crohn's disease.

METHODS

In the present evaluation, 247 prospectively evaluated Crohn's disease patients (24.3%), from a consecutively accumulated population database of 1015 patients, were found to have an epithelioid granuloma. The recently devised Montreal classification for Crohn's disease was then applied to this granuloma-positive cohort of Crohn's disease patients to define age at diagnosis for men and women, disease site and disease behaviour.

RESULTS

The investigation showed that patients with Crohn's disease and granulomas were most often diagnosed early in the course of their disease, particularly women. Their disease was often extensive, with ileocolonic and upper gastrointestinal tract involvement. Finally, disease behaviour was most often complex, especially with penetrating disease complications.

CONCLUSION

Using homogeneous (ie, 'reagent-grade') patient cohorts defined by a recently devised classification method for Crohn's disease, the study demonstrated that an epithelioid granuloma may represent a histopathological marker for an early biological event in the etiopathogenesis of Crohn's disease, and this may have predictive significance with respect to the location and clinical behaviour of Crohn's disease.

Frequency of epithelioid granulomas in colonoscopic biopsy specimens from paediatric and adult patients with Crohn's colitis

AIMS

To test the assumption that epithelioid granulomas found in colonoscopic biopsy specimens in patients with Crohn's colitis are markers of a different clinical behaviour.

METHODS

Sections from colonoscopic biopsy specimens from 352 consecutive patients (119 children and 233 adults) were investigated.

RESULTS

A total of 1117 colonoscopies were performed: 293 in children (mean 2.46 per patient) and 824 in adults (mean 3.53 per patient) (p<0.05). Granulomas at initial colonoscopy were recorded in 67.2% (43/64) of children and 65.9% (27/41) of adults (p>0.6), and at subsequent colonoscopies in 53.8% (64/119) of children and 17.6% (41/233) of adults (p<0.05). Surgical intervention was required in 6.3% (4/64) of the children having previous granuloma, but also in 14.5% (8/55) of those without previous granuloma, the rate for operated adults being 26.8% (11/41) and 24.5% (47/192), respectively (p>0.6).

CONCLUSIONS

Granulomas in entry and/or in subsequent colonoscopic biopsy specimens in patients with Crohn's colitis did not predict the need for subsequent surgical intervention. The fact that the frequency of granulomas was significantly higher in children than in adults with Crohn's colitis (despite a higher mean number of colonoscopic biopsies in adults), and that granulomas were present in colonoscopic biopsy specimens but not in the subsequent surgical specimens from 50% of the paediatric and 36% of the adult patients strengthen the conviction that granulomas in Crohn's colitis might evolve or regress at different time intervals during the course of the disease. This behaviour would reflect a particular immunological reaction, an epiphenomenon from immature tissues-as in children-when challenged by the so far elusive aetiological agent responsible for Crohn's disease.

Pitfalls in the interpretation of nonneoplastic mucosal biopsies in inflammatory bowel disease

This review provides a summary of common diagnostic problems encountered by both pathologists and gastroenterologists when evaluating patients with diarrhea and in whom inflammatory bowel disease (IBD) is suspected. The two most common forms of IBD, ulcerative colitis (UC) and Crohn's disease (CD), may, in certain settings, show overlapping endoscopic and pathologic features, potentially resulting in diagnostic confusion. For instance, some cases of UC may show unusual CD-like features, such as rectal sparing, discontinuous disease, aphthous ulceration, ileal or extracolonic involvement, and granulomatous inflammation, all of which may be evident in mucosal biopsy specimens. CD may also present as a diffuse, superficial pancolitis with ileal sparing that mimics the endoscopic and histologic appearance of UC. Furthermore, other forms of colitis, such as microscopic colitis, diverticulitis, diversion colitis, and nonsteroidal anti-inflammatory drug (NSAID)-induced colonic injury may also show IBD-like changes in mucosal biopsies. The potential diagnostic pitfalls faced by physicians, as well as features that aid in the distinction among these entities, are discussed in detail in this review.

The prevalence of genetic and serologic markers in an unselected European population-based cohort of IBD patients

BACKGROUND AND AIM

The aetiology of inflammatory bowel disease (IBD) is unknown, but it has become evident that genetic factors are involved in disease susceptibility. Studies have suggested a north-south gradient in the incidence of IBD, raising the question whether this difference is caused by genetic heterogeneity. We aimed to investigate the prevalence of polymorphisms in CARD15 and TLR4 and occurrence of anti-Saccharomyces cerevisiae (ASCA) and antineutrophil cytoplasmic antibodies (pANCA) in a European population-based IBD cohort.

METHODS

Individuals from the incident cohort were genotyped for three mutations in CARD15 and the Asp299gly mutation in TLR4. Levels of ASCA and pANCA were assessed. Disease location and behaviour at time of diagnosis was obtained from patient files.

RESULTS

Overall CARD15 mutation rate was 23.9% for CD and 9.6% for UC patients (P < 0.001). Mutations were less present in the Scandinavian countries (12.1%) versus the rest of Europe (32.8%) (P < 0.001). Overall population attributable risk was 11.2%. TLR4 mutation rate was 7.6% in CD, 6.7% in UC patients and 12.3% in healthy controls (HC), highest among South European CD patients and HC. ASCA was seen in 28.5% of CD patients with no north-south difference, and was associated with complicated disease. pANCA was most common in North European UC patients and not associated with disease phenotype.

CONCLUSION

The prevalence of mutations in CARD15 varied across Europe, and was not correlated to the incidence of CD. There was no association between mutations in TLR4 and IBD. The prevalence of ASCA was relatively low; however related to severe CD.

Associations between NOD2/CARD15 genotype and phenotype in Crohn’s disease-Are we there yet?

There have been multiple NOD2/CARD15 genotype-phenotype analyses undertaken in patients with Crohn's disease since the gene’s discovery in 2001. This review focuses on the major published series based upon their size and on the presence of specific clinical and genetic information provided in the published material from 2001 to 2005. Twelve studies provided raw data to carry out comparisons of disease location while ten studies included analysis of NOD2/CARD15 genotypes. NOD2/CARD15 variant frequency in ileal disease did not differ significantly among studies, whereas a comparison of disease location demonstrated highly significant differences among studies. Meta-analysis confirmed significant associations between NOD2/CARD15 variants and both ileal and ileocolonic disease locations, and with both stricturing and penetrating forms of disease behavior. This review underlines the significant phenotypic differences that exist among populations, including similar ethnic groups, and has demonstrated the need for further studies of patients with long-term “inflammatory” Crohn’s disease.

The roles of bacteria and TLR4 in rat and murine models of necrotizing enterocolitis

Bacteria are thought to contribute to the pathogenesis of necrotizing enterocolitis (NEC), but it is unknown whether their interaction with the epithelium can participate in the initiation of mucosal injury or they can act only following translocation across a damaged intestinal barrier. Our aims were to determine whether bacteria and intestinal epithelial TLR4 play roles in a well-established neonatal rat model and a novel neonatal murine model of NEC. Neonatal rats, C57BL/6J, C3HeB/FeJ (TLR4 wild type), and C3H/HeJ (TLR4 mutant) mice were delivered by Cesarean section and were subjected to formula feeding and cold asphyxia stress or were delivered naturally and were mother-fed. NEC incidence was evaluated by histological scoring, and gene expression was quantified using quantitative real-time PCR from cDNA generated from intestinal total RNA or from RNA obtained by laser capture microdissection. Spontaneous feeding catheter colonization or supplementation of cultured bacterial isolates to formula increased the incidence of experimental NEC. During the first 72 h of life, i.e., the time frame of NEC development in this model, intestinal TLR4 mRNA gradually decreases in mother-fed but increases in formula feeding and cold asphyxia stress, correlating with induced inducible NO synthase. TLR4, inducible NO synthase, and inflammatory cytokine induction occurred in the intestinal epithelium but not in the submucosa. NEC incidence was diminished in C3H/HeJ mice, compared with C3HeB/FeJ mice. In summary, bacteria and TLR4 play significant roles in experimental NEC, likely via an interaction of intraluminal bacteria and aberrantly overexpressed TLR4 in enterocytes.

Ileal lymphonodular hyperplasia is not associated with NOD2/CARD15 mutations

INTRODUCTION

Lymphonodular hyperplasia (LNH) is a mass of lymphoid tissue that has been described in the terminal ileum, colon and duodenum mainly in children. Controversy exists regarding the benign nature of LNH. The combination of chronic abdominal pain and hematochezia leads many of these patients to undergo investigations for inflammatory bowel diseases. NOD2/CARD15 on chromosome 16 has been identified as a susceptibility gene for Crohn disease (CD). No study has yet examined the possible association of NOD2/CARD15 mutations with patients with LNH. The purpose of this study was to investigate the presence of NOD2/CARD15 mutations in patients with clinically proven LNH.

METHODS

Children and young adults with gastrointestinal symptoms diagnosed as having terminal ileum LNH were eligible for the study.

RESULTS

The study group consisted of 32 patients (15 males and 17 females), age range 3-23 years, mean 13.1 +/- 5 years. Twenty-seven (84%) had abdominal pain, 3 (9%) had rectal bleeding. The duration of symptoms ranged from 1-60 months (17.9 +/- 14.5). Only 2 patients (6.2%) were found to be heterozygote for the NOD2/CARD15 mutation (1007 fs), whereas all of the others did not carry any of the 3 common mutant alleles. This number is significantly lower (P < 0.001) than the mutation prevalence demonstrated in both pediatric and adult Israeli CD patients.

CONCLUSIONS

NOD2/CARD15 mutations are not associated with LNH. This may strengthen the lack of association between CD and LNH that has been previously reported. We suggest that genotyping NOD2/CARD15 may help to distinguish LNH from inflammatory bowel diseases in selected patients.

Polymorphisms in the TNF-alpha promoter and variability in the granulomatous response in patients with Crohn's disease

Granulomas may be found in 30-70% of patients with Crohn's disease (CD). The etiology of granuloma formation in CD is presently unknown. Elevated levels of TNF-alpha are found within granuloma tissue, and are required to maintain granuloma formation in animal models. TNF-alpha production has been shown to influenced by TNF-alpha promoter polymorphisms. We hypothesized that heterogeneity for granulomas in CD might be influenced by the TNF-alpha promoter genotype. Patients with confirmed CD that had undergone full colonoscopy with multiple biopsies and/or surgical resection, served as the study group. One hundred healthy individuals served as a control population for genotyping. Patients and controls underwent genotyping for four TNF-alpha polymorphisms: 238G/A, 308 G/A,857 C/T, and 863 C/A. Inclusion and exclusion criteria were met in 155 patients (1-68 y). Polymorphisms in the TNF promoter were found in 16.6% (238G/A), 14.5% (308 G/A), 36.6% (857 C/T) and 30.7% (863G/A). No significant association was found for any of the individual polymorphisms with presence or absence of granulomas. In conclusion, we did not find an association between individual polymorphisms in the TNF-alpha promoter and presence of granulomas in CD. The reason for heterogeneity in granuloma formation in patients with CD remains elusive.

Association of intestinal granulomas with smoking, phenotype, and serology in Chinese patients with Crohn's disease

INTRODUCTION

Crohn's disease (CD) is a heterogenous disease characterized by variable manifestations and outcomes, and increasing in incidence in China. Phenotypic classification has been proposed to assist in subtyping of disease. Non-caseating intestinal granulomas are a hallmark of CD, but whether intestinal granulomas help predict Chinese CD phenotypes or determine severity, is not known.

AIMS

To determine the association between intestinal granulomas with CD phenotype, severity, risk factors, and serological markers.

METHODS

This was a single-centre study of consecutive definite Chinese CD cases. Granulomas were diagnosed by an experienced GI pathologist. Correlation with the Vienna Classification and other parameters was performed.

RESULTS

Eighty Chinese CD patients were recruited, 40 (50%) of whom had intestinal granulomas. Intestinal granulomas were independently associated with the stricturing behavior (OR: 4.71; 95% CI: 1.41-15.72), colonic location of disease (OR: 26.96; 95% CI: 2.68-271.14), but not with age of CD diagnosis. Current or previous smoking protected against the development of granulomas (OR: 0.16; 95% CI: 0.04-0.59). Granulomas were not associated with peri-anal involvement, extra-intestinal manifestations, anti-neutrophil cytoplasmic antibody or anti-Saccharomyces cerevisiae antibody serology, or severity of CD gauged by the requirement of major intestinal surgery or immunomodulating therapy.

CONCLUSIONS

Intestinal granulomas in the setting of CD may be helpful in determining phenotypic subtypes of CD, but is unhelpful in predicting disease severity. Smoking impairs the formation of granulomas in CD.

Diagnostic difficulties in inflammatory bowel disease pathology

This review summarizes some of the common diagnostic problems encountered by pathologists when evaluating patients with chronic colitis and in whom inflammatory bowel disease (IBD) is either suspected or within the differential diagnosis. Both ulcerative colitis (UC) and Crohn's disease (CD) show characteristic, but non-specific, pathological features that may overlap and result in a diagnosis of 'indeterminate colitis' (IC). However, other reasons why pathologists may entertain a diagnosis of IC include failure to recognize or accept certain 'hardcore' histological features as indicative of CD, an attempt to classify cases of chronic colitis based on mucosal biopsy material or in the absence of adequate clinical and radiographic information, and the presence of other disease processes that mask, or mimic, IBD. In addition, some cases of UC may show unusual CD-like features, such as discontinuous or patchy disease, ileal inflammation, extracolonic inflammation, granulomatous inflammation in response to ruptured crypts, aphthous ulcers, or transmural inflammation. Furthermore, other forms of colitis, such as microscopic colitis, diverticulitis and diversion colitis may, on occasion, also show IBD-like changes. The clinical and pathological features that aid in the distinction between these entities, and others, are covered in detail in this review.

Blau syndrome and related genetic disorders causing childhood arthritis

Blau Syndrome (BS) is an inheritable disorder characterized by granulomatous polyarthritis, panuveitis, and exanthema. It was described by Edward Blau in 1985, the same year in which Douglas Jabs reported a very similar family. Clinically indistinguishable from early onset sarcoidosis (EOS), both are now known to share a mutated form of caspase recruitment domain-15 (CARD 15), a protein involved in activation of nuclear factor kappa B which is in turn an up-regulator of pro-inflammatory cytokine transcription. An association between BS and EOS was suspected for years given the striking similarities of the core triad (arthritis-uveitis-dermatitis) and a common emerging pattern of systemic involvement. Hence, the familial form (BS) and the sporadic form (EOS) are almost certainly the same illness/defect, inherited in the first and acquired in the second as a result in most cases of a de novo mutation. Another form of granulomatous arthritis with uveitis, Crohn's disease, has also been associated with mutations in CARD 15 (albeit at a different domain) and despite similar phenotypes there are obvious differences including gut inflammation and pyoderma gangrenosum in Crohn's disease. This paper will review the clinical characteristics of these three disorders and their association with mutations in the CARD 15 gene.

Genotype-phenotype analysis in childhood-onset Crohn's disease: NOD2/CARD15 variants consistently predict phenotypic characteristics of severe disease

INTRODUCTION

The incidence of early-onset CD in Scotland is among the highest worldwide. Three single nucleotide polymorphisms (SNPs) R702W, G908R and Leu1007finsC in the NOD2/CARD15 gene predispose to adult CD. We investigated the contribution of these variants to disease susceptibility and phenotype in the Scottish early-onset IBD population.

PATIENTS AND METHODS

906 individuals including 247 Scottish IBD patients aged <16 years at diagnosis, 414 parents and 245 controls were genotyped. Transmission disequilibrium testing (TDT), case-control analysis and detailed genotype-phenotype analysis were performed.

RESULTS

The Leu1007finsC variant was associated with susceptibility to CD by case-control (4.2% versus. 1.4%, P = 0.01) and TDT analysis (P = 0.006). The Population Attributable Risk (PAR) for the 3 NOD2/CARD15 mutations was 7.9%. Carriage of NOD2/CARD15 variants was associated with, at diagnosis: decreased albumin (31.0% versus. 9.0%, P = 0.001) and raised CRP (25% versus. 9.5%, P = 0.04) and at follow up: need for surgery (39.5% versus. 12.8%, P = 0.0002) jejunal involvement (50% versus. 18.4%, P = 0.01) jejunal and ileal involvement (50% versus. 10.7%, P = 0.009), raised CRP (57.1% and 12.8%, P = 0.0009), lower weight/height centile (75.0% versus. 20.2%, P = 0.03, 50.0% versus. 16.0%, P = 0.001 respectively) and stricturing disease (45.5% versus. 19.4%, P < 0.05). Multifactorial analysis demonstrated carriage was associated with need for surgery (P = 0.004, OR 4.9 [1.5-14.7]).

CONCLUSIONS

These NOD2/CARD 15 variants in the Scottish early onset CD population have a definite, albeit relatively small contribution to CD susceptibility (PAR 7.9%) but a major impact on phenotype. In particular NOD2/CARD15 variants are strongly associated with several markers of disease severity in pediatric CD, notably need for surgery.

Innate immune receptor genetic polymorphisms in pouchitis: is CARD15 a susceptibility factor?

BACKGROUND

Pouchitis is a frequent complication after ileal pouch-anal anastamosis (IPAA) for ulcerative colitis (UC). The aim of this study was to determine whether genetic polymorphisms in the innate immune receptors toll-like receptor (TLR)4 and caspase activation and recruitment domain family member 15 (CARD15) genes are associated with pouchitis.

METHODS

From a retrospectively ascertained cohort of patients with UC 5 to 12 years after IPAA (n = 101), subjects were classified into 3 groups: no pouchitis (n = 52); 1 to 2 episodes per year (n = 11), and more than 2 episodes per year (n = 38). Single nucleotide polymorphisms in the tlr4 gene (D299G, T399I) were determined by a real-time polymerase chain reaction-based fluorogenic probe technique; and card15 polymorphisms (L1007fsinsC, R702W, G908R) were determined by pyrosequencing.

RESULTS

Pouchitis affected 49% (49/101) of the study population. No correlation between pouchitis and the presence of TLR4 polymorphisms was found. The percentage of patients who harbored CARD15 mutations was significantly higher in patients with pouchitis than in patients without pouchitis (18% versus 8%; P < 0.05); 24% of pouchitis patients with more than 2 episodes per year harbored CARD15 mutations (P < 0.01 compared with the no pouchitis group). The CARD15 insertion mutation L1007fsinsC was present in 14% of patients with pouchitis and in 0% without pouchitis (P < 0.05). All patients who carried L1007fsinsC developed more than 2 episodes per year.

CONCLUSIONS

CARD15 polymorphisms are seen in greater frequency in patients with pouchitis after IPAA for UC. These findings, if borne out in prospective analyses, suggest that CARD15 mutations, particularly L1007fsinsC, may predispose to the development of pouchitis after IPAA for UC.

Caspase recruitment domain 15 mutations and rheumatic diseases

PURPOSE OF REVIEW

The purpose of this article is to review the foundational work and current developments on a group of rheumatic disorders associated with mutations in the caspase recruitment domain 15/nucleotide oligomerization domain 2 gene.

RECENT FINDINGS

To date, there are at least 10 arthritic conditions for which specific genetic mutations have been demonstrated. They include familial Mediterranean fever; tumor necrosis factor receptor associated periodic syndrome; hyper immunoglobulin D syndrome; neonatal onset multisystemic inflammatory disease; pyogenic arthritis pyoderma gangrenosum and acne; Muckle-Wells syndrome; familial cold autoinflammatory syndrome; immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome; Crohn's disease; and familial and sporadic sarcoid granulomatous arthritis. This review focuses on recent progress in the last two diseases and the caspase recruitment domain 15 genetic defects with which they are associated. Up to 50% of patients with familial granulomatous arthritis (Blau's syndrome), 90% of those with sporadic granulomatous arthritis (early-onset sarcoidosis), and 40% of individuals with Crohn's disease have documented mutations in the caspase recruitment domain 15 gene.

SUMMARY

Although histologically, Crohn's disease and familial and sporadic sarcoid granulomatous arthritis are distinct from rheumatoid arthritis because of the defining presence (albeit in not all cases) of non-caseating granulomata in the synovial and intestinal tissues, respectively, they still represent a promising model of both chronic synovitis and uveitis. In addition, once the actual mechanism is discovered by which defects of the caspase recruitment domain 15 gene product lead to chronic arthritis, it may uncover unsuspected biologic targets for therapeutics.

Bacterial interactions with cells of the intestinal mucosa: Toll-like receptors and NOD2

Toll-like receptors (TLR) and NOD2 are emerging as key mediators of innate host defence in the intestinal mucosa, crucially involved in maintaining mucosal as well as commensal homeostasis. Recent observations suggest new (patho-) physiological mechanisms of how functional versus dysfunctional TLRx/NOD2 pathways may oppose or favour inflammatory bowel disease (IBD). In health, TLRx signalling protects the intestinal epithelial barrier and confers commensal tolerance whereas NOD2 signalling exerts antimicrobial activity and prevents pathogenic invasion. In disease, aberrant TLRx and/or NOD2 signalling may stimulate diverse inflammatory responses leading to acute and chronic intestinal inflammation with many different clinical phenotypes.