Inflammatory bowel disease diagnosis, evaluation and classification: state-of-the art approach

A literature review on large intestinal hyperelastic constitutive modeling

Impacts, traumas and strokes are spontaneously life-threatening, but chronic symptoms strangle patient every day. Colorectal tissue mechanics in such chronic situations not only regulates the physio-psychological well-being of the patient, but also confirms the level of comfort and post-operative clinical outcomes. Numerous uniaxial and multiaxial tensile experiments on healthy and affected samples have evidenced significant differences in tissue mechanical behavior and strong colorectal anisotropy across each layer in thickness direction and along the length. Furthermore, this study reviewed various forms of passive constitutive models for the highly fibrous colorectal tissue ranging from the simplest linearly elastic and the conventional isotropic hyperelastic to the most sophisticated second harmonic generation image based anisotropic mathematical formulation. Under large deformation, the isotropic description of tissue mechanics is unequivocally ineffective which demands a microstructural based tissue definition. Therefore, the information collected in this review paper would present the current state-of-the-art in colorectal biomechanics and profoundly serve as updated computational resources to develop a sophisticated characterization of colorectal tissues.

Linking bacterial enterotoxins and alpha defensin 5 expansion in the Crohn's colitis: A new insight into the etiopathogenetic and differentiation triggers driving colonic inflammatory bowel disease

Evidence link bacterial enterotoxins to apparent crypt-cell like cells (CCLCs), and Alpha Defensin 5 (DEFA5) expansion in the colonic mucosa of Crohn's colitis disease (CC) patients. These areas of ectopic ileal metaplasia, positive for Paneth cell (PC) markers are consistent with diagnosis of CC. Retrospectively, we: 1. Identified 21 patients with indeterminate colitis (IC) between 2000-2007 and were reevaluation their final clinical diagnosis in 2014 after a followed-up for mean 8.7±3.7 (range, 4-14) years. Their initial biopsies were analyzed by DEFA5 bioassay. 2. Differentiated ulcer-associated cell lineage (UACL) analysis by immunohistochemistry (IHC) of the CC patients, stained for Mucin 6 (MUC6) and DEFA5. 3. Treated human immortalized colonic epithelial cells (NCM460) and colonoids with pure DEFA5 on the secretion of signatures after 24hr. The control colonoids were not treated. 4. Treated colonoids with/without enterotoxins for 14 days and the spent medium were collected and determined by quantitative expression of DEFA5, CCLCs and other biologic signatures. The experiments were repeated twice. Three statistical methods were used: (i) Univariate analysis; (ii) LASSO; and (iii) Elastic net. DEFA5 bioassay discriminated CC and ulcerative colitis (UC) in a cohort of IC patients with accuracy. A fit logistic model with group CC and UC as the outcome and the DEFA5 as independent variable differentiator with a positive predictive value of 96 percent. IHC staining of CC for MUC6 and DEFA5 stained in different locations indicating that DEFA5 is not co-expressed in UACL and is therefore NOT the genesis of CC, rather a secretagogue for specific signature(s) that underlie the distinct crypt pathobiology of CC. Notably, we observed expansion of signatures after DEFA5 treatment on NCM460 and colonoids cells expressed at different times, intervals, and intensity. These factors are key stem cell niche regulators leading to DEFA5 secreting CCLCs differentiation 'the colonic ectopy ileal metaplasia formation' conspicuously of pathogenic importance in CC.

Prevalence of Celiac Disease in Children and Adolescents With Inflammatory Bowel Disease

Introduction

The association between inflammatory bowel disease (IBD) - particularly its two main subtypes, ulcerative colitis (UC) and Crohn’s disease (CD) - and celiac disease (CeD) has been attributed to an overlap in the mechanism of immune dysregulation that characterizes these conditions. Owing to the paucity of studies that have explored this condition in pediatric patients, we examined the prevalence of CeD in children with IBD.

Materials and methods

This is a cross-sectional study of children aged two to 18 years with IBD that were diagnosed between 2016 and 2018. Clinical, demographic, laboratory, and endoscopic data were analysed. Serology for CeD measured the immunoglobulin A tissue transglutaminase (IgA-tTG) antibodies, and the diagnosis was confirmed histologically through small bowel biopsies.

Results

The study included 101 patients with IBD (83.2% with UC and 16.8% with CD). The mean age was 8.7±4.0 years. Males constituted 59.4% of the cohort, and only 3% had perianal disease. Ileocolonic involvement was reported in 64.7% and non-stricturing and non-penetrating behaviour in 76.7% of CD patients. Pancolitis constituted 45.2% of UC patients. Ten patients (9.9%) had positive serology based on IgA-tTG antibodies, three (approximately 3%) had CeD based on biopsy findings, two patients (2%) had CD, and one patient (1%) had UC. Patients with confirmed CeD had a significantly higher frequency of symptoms of gaseous sensation and bloating (P=0.003) and abdominal distension (P=0.04).

Conclusions

The prevalence of CeD in Egyptian children with IBD is higher than previously reported in a number of similar studies. Abdominal bloating and gaseous sensation were identified as associated symptoms.

Histological Remission in Ulcerative Colitis: Under the Microscope Is the Cure

In recent years, the therapeutic goals in ulcerative colitis (UC) have become increasingly stringent. Histological features seem to be a reliable predictor of disease outcomes after therapy, and histological remission (HR) is the new frontier in the treatment of UC. Here, we first provide a historical perspective before reviewing indexes in the era of biologics; histology as a treatment goal in UC trials; the poor correlation between symptoms, endoscopy, and histology; and the impact of histology on disease outcomes. HR seems to be a promising end point for the treatment of UC because it is typically associated with better outcomes. Two new validated indexes are available to assess histology more accurately in trials, and they may also be applicable to clinical practice. Additional interventional trials are now necessary to establish definitions of HR and its potential for disease modification.

Enteroendocrine Cells: Sensing Gut Microbiota and Regulating Inflammatory Bowel Diseases

Host sensing in the gut microbiota has been crucial in the regulation of intestinal homeostasis. Although inflammatory bowel diseases (IBDs), multifactorial chronic inflammatory conditions of the gastrointestinal tract, have been associated with intestinal dysbiosis, the detailed interactions between host and gut microbiota are still not completely understood. Enteroendocrine cells (EECs) represent 1% of the intestinal epithelium. Accumulating evidence indicates that EECs are key sensors of gut microbiota and/or microbial metabolites. They can secrete cytokines and peptide hormones in response to microbiota, either in traditional endocrine regulation or by paracrine impact on proximal tissues and/or cells or via afferent nerve fibers. Enteroendocrine cells also play crucial roles in mucosal immunity, gut barrier function, visceral hyperalgesia, and gastrointestinal (GI) motility, thereby regulating several GI diseases, including IBD. In this review, we will focus on EECs in sensing microbiota, correlating enteroendocrine perturbations with IBD, and the underlying mechanisms.

Prevalance of Celiac Disease in Patients with Inflammatory Bowel Disease in Turkish Population

Background

Celiac disease (CD) and inflammatory bowel disease (IBD) involve inflammation of the gastrointestinal lumen, which environmental, genetic, and immunological factors have a role in their pathogenesis. The prevalence of celiac disease in IBD ranges from 0% to 14%. In this study, our aim was to determine the prevalence of CD in IBD patients followed by us who are attending the hospital or outpatient clinic over a period of time of seven years.

Methods

Seven hundred and fifty nine patients (425 M, 334 F, mean age: 46.75, 396 ulcerative colitis (UC), 363 Crohn's disease (CrD)) diagnosed and followed up for IBD between January 2009 and July 2016 were evaluated retrospectively, and clinical, demographic, laboratory, and endoscopic data were collected.

Results

CD was investigated in 79 (%10.4) inflammatory bowel disease patients according to symptoms, and in 5.06% (n = 4) of them, we diagnosed CD. The most common indication for investigating for CD was iron deficiency anemia unreponsive to iron supplementation.

Conclusions

We did not find an increased prevalance of celiac disease in Turkish IBD patients in this study. In the presence of refractory iron deficiency anemia without any other cause in IBD patients, investigations for celiac disease should be considered.

Development and validation of the Nancy histological index for UC

OBJECTIVE

We developed a validated index for assessing histological disease activity in UC and established its responsiveness.

METHODS

Two hundred biopsies were scored. The outcome was the Global Visual Evaluation (GVE). Eight histological features were tested. The Nancy index was developed by multiple linear regression and bootstrap process to create an index that best matched the GVE. Goodness of fit was assessed by the adjusted R squared (adjusted R²). The second step was the validation of the index: 100 biopsies were scored for the Nancy index by three pathologists from different centres. Inter-reader reliability was evaluated for each reader. The relationship between the change of the Nancy index and the Geboes index was assessed to assess the responsiveness.

RESULTS

After backward selection with bootstrap validation, 3/8 items were selected: ulceration (adjusted R²=0.55), acute inflammatory infiltrate (adjusted R²=0.88) and chronic inflammatory infiltrate (adjusted R²=0.79). The Nancy index is defined by a 5-level classification ranging from grade 0 (absence of significant histological disease activity) to grade 4 (severely active disease). The intraclass correlation coefficient (ICC) for the intrareader reliability was 0.88 (95% CI 0.82 to 0.92) and the index had good inter-reader reliability (ICC=0.86 (0.81 to 0.99)). The correlation between the Nancy index and the Geboes score or the GVE was very good. The index had a good responsiveness with a high correlation between changes in the Geboes score and changes in the Nancy index (0.910 (0.813 to 0.955)).

CONCLUSIONS

A three descriptor histological index has been validated for use in clinical practice and clinical trials.

Human alpha defensin 5 is a candidate biomarker to delineate inflammatory bowel disease

Inability to distinguish Crohn's colitis from ulcerative colitis leads to the diagnosis of indeterminate colitis. This greatly effects medical and surgical care of the patient because treatments for the two diseases vary. Approximately 30 percent of inflammatory bowel disease patients cannot be accurately diagnosed, increasing their risk of inappropriate treatment. We sought to determine whether transcriptomic patterns could be used to develop diagnostic biomarker(s) to delineate inflammatory bowel disease more accurately. Four patients groups were assessed via whole-transcriptome microarray, qPCR, Western blot, and immunohistochemistry for differential expression of Human α-Defensin-5. In addition, immunohistochemistry for Paneth cells and Lysozyme, a Paneth cell marker, was also performed. Aberrant expression of Human α-Defensin-5 levels using transcript, Western blot, and immunohistochemistry staining levels was significantly upregulated in Crohn's colitis, p< 0.0001. Among patients with indeterminate colitis, Human α-Defensin-5 is a reliable differentiator with a positive predictive value of 96 percent. We also observed abundant ectopic crypt Paneth cells in all colectomy tissue samples of Crohn's colitis patients. In a retrospective study, we show that Human α-Defensin-5 could be used in indeterminate colitis patients to determine if they have either ulcerative colitis (low levels of Human α-Defensin-5) or Crohn's colitis (high levels of Human α-Defensin-5). Twenty of 67 patients (30 percent) who underwent restorative proctocolectomy for definitive ulcerative colitis were clinically changed to de novo Crohn's disease. These patients were profiled by Human α-Defensin-5 immunohistochemistry. All patients tested strongly positive. In addition, we observed by both hematoxylin and eosin and Lysozyme staining, a large number of ectopic Paneth cells in the colonic crypt of Crohn's colitis patient samples. Our experiments are the first to show that Human α-Defensin-5 is a potential candidate biomarker to molecularly differentiate Crohn's colitis from ulcerative colitis, to our knowledge. These data give us both a potential diagnostic marker in Human α-Defensin-5 and insight to develop future mechanistic studies to better understand crypt biology in Crohn's colitis.

Comparing histological activity indexes in UC

BACKGROUND

Assessment of disease activity in UC is important for designing an optimal therapeutic strategy. No single histology score is considered optimum. The aim of this study was to compare intraobserver reproducibility and the interobserver agreement of available histological UC activity indexes.

METHODS

One hundred and two biopsy specimens (collected between 2003 and 2014) were scored blindly by three pathologists by determining Geboes, Riley, Gramlich and Gupta indexes and global visual evaluation (GVE). Intraobserver reproducibility and interobserver agreements for index and items of index were studied by intraclass correlation coefficient for quantitative parameter and by κ values and Krippendorff index for qualitative parameters. Relationship between indexes was studied by computation of Pearson's and Spearman's correlation coefficients.

RESULTS

Geboes, Riley, Gramlich and Gupta indexes and GVE showed good intraobserver reproducibility and a good interobserver agreement. Histological items that showed the best interobserver agreement were 'erosion/ulceration or surface epithelial integrity' and 'acute inflammatory cells infiltrate/neutrophils in lamina propria'. The five scores were strongly correlated.

CONCLUSIONS

Correlation between indexes is strong. Intraobserver reproducibility and interobserver agreement for all indexes is very good. Histological items that showed the best interobserver agreement are 'erosion/ulceration' and 'acute inflammatory cells infiltrate/neutrophils in lamina propria'.

Correlation between the endoscopic and histologic score in assessing the activity of ulcerative colitis

BACKGROUND

In routine practice, scoring of activity and severity of ulcerative colitis is based on combined clinical and endoscopic assessment. Histology also allows sensitive scoring of ulcerative colitis activity. The correlation between endoscopy and histology has not been investigated thoroughly. It is still unknown how well they correlate and whether scoring both endoscopy and histology better reflects the true disease activity than each of the methods separately.

METHODS

Two hundred and sixty-three biopsy sets from 131 known patients with ulcerative colitis were reviewed by an experienced gastrointestinal pathologist and scored using the Geboes and Riley histologic scoring systems. Endoscopic scoring had been performed previously by inflammatory bowel disease specialists using the Mayo endoscopic subscore. Bidirectional comparison of the Mayo endoscopic subscore with the full and converted histologic scores was then performed.

RESULTS

We found a statistically significant overall correlation between the Mayo endoscopic subscore and the histologic scores (highest correlation: Kendall's τ = 0.482, P < 0.0001). Although a very high concordance was found for inactive and severely active disease, a high diversity was detected between these extremes. For example, endoscopic mildly active disease (Mayo 1) was distributed over all different histologic grades (37%, grade 0; 21%, grade 1; 28%, grade 2; and 14%, grade 3).

CONCLUSIONS

Both extremes of the histologic and endoscopic activity scores neatly correlate, but important misclassifications exist for mild disease. Microscopy may detect more severe disease than endoscopically suspected, possibly altering the clinical follow-up scheme. We also infer from our results that histologic scoring should be used in addition to endoscopy when scoring disease activity for clinical trials.

Laparoscopic surgery for inflammatory bowel disease--the experience in China

BACKGROUND

The incidence of inflammatory bowel disease (IBD) has risen rapidly in China over the last 15 years. Increasing numbers of people with IBD require surgery during their lifetime, but few reports of IBD in Eastern populations have been described to date. The aim of this study was to assess the short-term effects of the laparoscopic surgery for IBD in Chinese patients.

MATERIALS AND METHODS

From February 2010 to March 2012, 35 patients with IBD underwent laparoscopic operations and the clinical data obtained for these patients were reviewed.

RESULTS

Patients with Crohn's disease (CD) (N = 21) and ulcerative colitis (UC) (N = 14) underwent laparoscopic surgery. In the CD group, the mean age was 37.4 years. Two patients (9.5%) required conversion to an open procedure. The median length of postoperative hospitalization was 9 (7-40) days. Overall morbidity was 26.3% and no patients required re-operation. In the UC group, the mean age was 55.2 years. The conversion rate was 14.3% (2/14). The median time to regular diet was 4 (3-10) days and the median length of postoperative hospitalization was 8 (7-25) days. Four patients developed postoperative complications and one patient developed ileostomy retraction requiring urgent operative intervention to rebuild the stoma.

CONCLUSIONS

Laparoscopic surgery in patients with IBD can be accomplished safely and with reasonable operative times, conversion rates and morbidity rates. The main advantages of the laparoscopic approach are rapid recovery, improved cosmesis, less postoperative pain, and patient satisfaction.

Differential expression of the TL1A/DcR3 system of TNF/TNFR-like proteins in large vs. small intestinal Crohn's disease

BACKGROUND

TNF-like cytokine 1A provides co-stimulatory signals to activated lymphocytes through binding to death-domain receptor-3. Decoy receptor-3 inhibits death-domain receptor-3 signalling, rendering immunocytes resistant to apoptosis. These functions may be important for the pathogenesis of Crohn's disease.

AIMS

To study the mucosal and systemic expression of Decoy receptor-3 and TNF-like cytokine 1A in Crohn's disease, in relation to disease activity, localization, and response to treatment.

METHODS

Soluble Decoy receptor-3 and TNF-like cytokine 1A were measured by ELISA in active or quiescent Crohn's disease. Relative mRNA expression in non-affected and inflamed intestinal mucosa was determined by real-time RT-PCR.

RESULTS

We found significant upregulation of Decoy receptor-3 and its ligands TNF-like cytokine 1A and FasL in inflamed intestinal mucosa of Crohn's disease patients. During active disease, Decoy receptor-3 and TNF-like cytokine 1A were detected in the serum in the majority of patients. Intestinal inflammation was strongly associated with these elevations as they were absent during remission and significantly reduced with anti-inflammatory treatment. Regional diversity was observed as Decoy receptor-3 was upregulated in colonic and ileal sites, whereas TNF-like cytokine 1A was preferentially induced in the large bowel mucosa and systemic circulation of patients with colonic involvement.

CONCLUSIONS

TNF-like cytokine 1A and Decoy receptor-3 are upregulated during active Crohn's disease and may participate in disease pathogenesis and offer novel therapeutic opportunities.

High levels of Crohn's disease-associated anti-microbial antibodies are present and independent of colitis in chronic granulomatous disease

Chronic granulomatous disease (CGD) and inflammatory bowel disease (IBD) have overlapping gastrointestinal manifestations. Serum antibodies to intestinal microbial antigens in IBD are thought to reflect a loss of tolerance in the setting of genetically encoded innate immune defects. CGD subjects studied here, with or without colitis, had considerably higher levels of ASCA IgA, ASCA IgG, anti-OmpC, anti-I2, and anti-CBir1, but absent to low pANCA, compared to IBD-predictive cutoffs. Higher antibody levels were not associated with a history of colitis. Except for higher ASCA IgG in subjects <18 years, antibody levels were not age-dependent. In comparison, 7 HIES subjects expressed negative to low antibody levels to all of these antigens; none had colitis. Our results suggest that markedly elevated levels of antimicrobial antibodies in CGD do not correlate with a history of colitis but may reflect a specific defect in innate immunity in the face of chronic antigenic stimulation.

Prevalence of celiac disease in inflammatory bowel diseases: An IG-IBD multicentre study

BACKGROUND

An association has been described in case reports between celiac disease and inflammatory bowel diseases. The aim of the present study is to assess the prevalence of celiac disease in a large series of Italian patients with inflammatory bowel disease.

METHODS

The Italian Group for Inflammatory Bowel Disease conducted a multicentre study between January 2002 and December 2004, in which 22 gastroenterology centres in Italy enrolled 1711 consecutive outpatients with inflammatory bowel disease. 860 (50.2%) had Crohn's disease (415 females, mean age 40, range 18-75), 791 (46.2%) had ulcerative colitis (371 females, mean age 40, range 18-80), and 60 (3.5%) had indeterminate colitis (27 females, mean age 40, range 18-78). All patients underwent serological testing for anti-endomysial antibodies and anti-tissue transglutaminase antibodies; if positive upper GI endoscopy with duodenal biopsy was performed.

RESULTS

Nine of the 1711 patients (0.5%) had serological and histological findings compatible with the diagnosis of celiac disease; six of them had ulcerative colitis and three had Crohn's disease.

CONCLUSIONS

Overall we found a lower risk of celiac disease in our cohort of inflammatory bowel disease patients than in the general population; prevalence of celiac disease was higher in patients with ulcerative colitis than in those with Crohn's disease.

Interstitial cells of Cajal, macrophages and mast cells in the gut musculature: morphology, distribution, spatial and possible functional interactions

Interstitial cells of Cajal (ICC) are recognized as pacemaker cells for gastrointestinal movement and are suggested to be mediators of neuromuscular transmission. Intestinal motility disturbances are often associated with a reduced number of ICC and/or ultrastructural damage, sometimes associated with immune cells. Macrophages and mast cells in the intestinal muscularis externa of rodents can be found in close spatial contact with ICC. Macrophages are a constant and regularly distributed cell population in the serosa and at the level of Auerbach's plexus (AP). In human colon, ICC are in close contact with macrophages at the level of AP, suggesting functional interaction. It has therefore been proposed that ICC and macrophages interact. Macrophages and mast cells are considered to play important roles in the innate immune defence by producing pro-inflammatory mediators during classical activation, which may in itself result in damage to the tissue. They also take part in alternative activation which is associated with anti-inflammatory mediators, tissue remodelling and homeostasis, cancer, helminth infections and immunophenotype switch. ICC become damaged under various circumstances - surgical resection, possibly post-operative ileus in rodents - where innate activation takes place, and in helminth infections - where alternative activation takes place. During alternative activation the muscularis macrophage can switch phenotype resulting in up-regulation of F4/80 and the mannose receptor. In more chronic conditions such as Crohn's disease and achalasia, ICC and mast cells develop close spatial contacts and piecemeal degranulation is possibly triggered.

Certolizumab pegol for the management of Crohn's disease in adults

BACKGROUND

Crohn's disease (CD) is an inflammatory disorder that can affect any portion of the gastrointestinal tract, from the mouth to the rectum. The American Gastroenterological Association recommends that treatment with anti-tumor necrosis factor (TNF)-alpha be considered in patients with moderate to severe CD refractory to concomitant aminosalicylates, corticosteroids, or immunosuppressive treatment, or who have contraindications to or poor tolerance of these agents. Anti-TNF-alpha agents available in the United States for the management of CD are infliximab, adalimumab, and certolizumab pegol. The latter is a recombinant humanized antibody Fab' fragment against TNF-alpha. It is conjugated with a 40-kDa polyethylene glycol molecule to increase the t(1/2) of the treatment to approximately 2 weeks.

OBJECTIVE

The objective of this review was to extract and assess all relevant available data on the efficacy and tolerability of certolizumab pegol in the treatment of CD.

METHODS

Searches of MEDLINE and International Pharmaceutical Abstracts from 1985 to March 3, 2009, were conducted using the key terms certolizumab pegol, CDP870, and Crohn's disease. Data from all available clinical trials published in English and ongoing trials were included in this review. The reference lists of the identified articles were searched for additional references. Data from abstracts presented at the annual meetings of the American College of Gastroenterology and Digestive Disease Week from 2004 to 2008 were reviewed and included if relevant.

RESULTS

A total of 8 studies were included in this review (1474 patients). In Phase II trials, there were no significant differences between certolizumab pegol and inactive vehicle (placebo) in week-4 or week-12 clinical response or remission rates. In the first of 2 Phase III clinical trials, certolizumab pegol was associated with significantly greater rates of response compared with placebo at weeks 6 (37% vs 26%; P = 0.04) and 26 (22% vs 12%; P = 0.05) of induction treatment (data from patients with baseline CRP concentrations > or =10 mg/L). Response was defined as a decrease from baseline in CD activity index > or =100 at week 6 and at both weeks 6 and 26 in patients with baseline C-reactive protein > or =10 mg/L. Remission rates were not significantly different between the 2 groups. In the second Phase III trial, the proportion of patients in whom response was sustained up to 26 weeks was significantly greater with certolizumab pegol compared with placebo (63% vs 36%; P < 0.001). The tolerability profile of certolizumab pegol was similar to those of other anti-TNF-alpha agents and included an increased risk for infections (including opportunistic infections [eg, tuberculosis]) compared with placebo. Infusion and injection-site reactions were infrequent (3%) with certolizumab pegol treatment. The most common adverse events reported with certolizumab pegol treatment included upper respiratory infection (20%), immunogenicity (8%), and urinary tract infection (7%). No new unanticipated adverse events emerged during the 30-month tolerability follow-up. Certolizumab pegol is being assessed in patients with CD refractory to other medications, including other biologic agents.

CONCLUSIONS

Based on the findings from the present review, certolizumab pegol had moderate efficacy in the treatment of moderate to severe, active CD. In well-designed Phase III clinical trials, certolizumab pegol was associated with significantly greater response rates compared with placebo at weeks 6 and 26 of induction treatment. In patients who responded to the 6-week induction, certolizumab pegol administered as a monthly subcutaneous injection was effective in maintaining CD response and remission. Findings from studies of certolizumab pegol in refractory CD are awaited.

Immunocapture and identification of cell membrane protein antigenic targets of serum autoantibodies

There is increasing interest in the role of antibodies targeting specific membrane proteins in neurological and other diseases. The target(s) of these pathogenic antibodies is known in a few diseases, usually when candidate cell surface proteins have been tested. Approaches for identifying new antigens have mainly resulted in the identification of antibodies to intracellular proteins, which are often very useful as diagnostic markers for disease but unlikely to be directly involved in disease pathogenesis because they are not accessible to circulating antibodies. To identify cell surface antigens, we developed a "conformational membrane antigen isolation and identification" strategy. First, a cell line is identified that reacts with patient sera but not with control sera. Second, intact cells are exposed to sera to allow the binding of presumptive autoantibodies to their cell surface targets. After washing off non-bound serum components, the cells are lysed, and immune complexes are precipitated. Third, the bound surface antigen is identified by mass spectrometry. As a model system we used a muscle cell line, TE671, that endogenously expresses muscle-specific tyrosine receptor kinase (MuSK) and sera or plasmas from patients with a subtype of the autoimmune disease myasthenia gravis in which patients have autoantibodies against MuSK. MuSK was robustly detected as the only membrane protein in immunoprecipitates from all three patient samples tested and not from the three MuSK antibody-negative control samples processed in parallel. Of note, however, there were many intracellular proteins found in the immunoprecipitates from both patients and controls, suggesting that these were nonspecifically immunoprecipitated from cell extracts. The conformational membrane antigen isolation and identification technique should be of value for the detection of highly relevant antigenic targets in the growing number of suspected antibody-mediated autoimmune disorders. The approach would also be very suitable for the analysis of human or experimental antitumor responses.

Multigene analysis can discriminate between ulcerative colitis, Crohn's disease, and irritable bowel syndrome

BACKGROUND & AIMS

Inflammatory bowel diseases (IBDs) and the irritable bowel syndrome (IBS) are heterogeneous disorders of the gastrointestinal tract and can profoundly affect the quality of life. Because many of the symptoms of IBD are similar to those of IBS, the former may be misdiagnosed. In addition, the 2 major forms of IBD, ulcerative colitis (UC) and Crohn's disease (CD), have overlapping nonspecific, pathologic features leading to difficulties in assessing colonic inflammation and hence the term IBD unclassified has been proposed. The aim of this study was to identify and assess the utility of a certain set of marker genes that could help to distinguish IBS from IBD, and further to discriminate between UC and CD.

METHODS

Subtractive suppression hybridization was used to identify IBD-specific genes in colonic mucosal biopsy specimens. In quantitative polymerase chain reaction experiments, the differential expressions of identified genes then were analyzed using a classification algorithm and the possible clinical value of these marker genes was evaluated in a total of 301 patients in 3 stepwise studies.

RESULTS

Seven marker genes were identified as differentially expressed in IBD, making it possible to discriminate between patients suffering from UC, CD, or IBS with area under the receiver-operating characteristic curves ranging from 0.915 to 0.999 (P < .0001) using the clinical diagnosis as gold standard.

CONCLUSIONS

Expression profiling of relevant marker genes in colonic biopsy specimens from patients with IBD/IBS-like symptoms may enable swift and reliable determination of diagnosis, ultimately improving disease management.