European Society for Pediatric Gastroenterology, Hepatology, and Nutrition guidelines for the diagnosis of coeliac disease

OBJECTIVE

Diagnostic criteria for coeliac disease (CD) from the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) were published in 1990. Since then, the autoantigen in CD, tissue transglutaminase, has been identified; the perception of CD has changed from that of a rather uncommon enteropathy to a common multiorgan disease strongly dependent on the haplotypes human leukocyte antigen (HLA)-DQ2 and HLA-DQ8; and CD-specific antibody tests have improved.

METHODS

A panel of 17 experts defined CD and developed new diagnostic criteria based on the Delphi process. Two groups of patients were defined with different diagnostic approaches to diagnose CD: children with symptoms suggestive of CD (group 1) and asymptomatic children at increased risk for CD (group 2). The 2004 National Institutes of Health/Agency for Healthcare Research and Quality report and a systematic literature search on antibody tests for CD in paediatric patients covering the years 2004 to 2009 was the basis for the evidence-based recommendations on CD-specific antibody testing.

RESULTS

In group 1, the diagnosis of CD is based on symptoms, positive serology, and histology that is consistent with CD. If immunoglobulin A anti-tissue transglutaminase type 2 antibody titers are high (>10 times the upper limit of normal), then the option is to diagnose CD without duodenal biopsies by applying a strict protocol with further laboratory tests. In group 2, the diagnosis of CD is based on positive serology and histology. HLA-DQ2 and HLA-DQ8 testing is valuable because CD is unlikely if both haplotypes are negative.

CONCLUSIONS

The aim of the new guidelines was to achieve a high diagnostic accuracy and to reduce the burden for patients and their families. The performance of these guidelines in clinical practice should be evaluated prospectively.

Tissue transglutaminase autoantibody enzyme-linked immunosorbent assay in detecting celiac disease

BACKGROUND & AIMS

Tissue transglutaminase has been reported to be the target for endomysial antibodies in celiac disease. We sought to establish whether immunoglobulin (Ig) A class tissue transglutaminase autoantibodies can be considered specific for celiac disease.

METHODS

Serum samples from 136 patients with untreated celiac disease (diagnosed according to the criteria of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition) and 207 disease controls were studied. Enzyme-linked immunosorbent assay (ELISA) and Western blots were performed using calcium-treated and untreated tissue transglutaminase as antigen. Reticulin, endomysial, and mouse monoclonal tissue transglutaminase antibodies were studied by an indirect immunofluorescence method and gliadin antibodies with ELISA.

RESULTS

The calcium-activated tissue transglutaminase autoantibody ELISA was highly sensitive (129 of 136) and specific (194 of 207) in detecting celiac disease. The new autoantibody ELISA test correlated well with the endomysial antibody test. Tissue transglutaminase autoantibody ELISA showed a clearly better predictive potential than the IgA class gliadin antibody ELISA. Immunoblots and ELISA blocking studies showed that calcium is needed for the specific antigen-antibody reaction to occur. Double immunofluorescence staining in human umbilical cord with sera from patients with celiac disease and with monoclonal tissue transglutaminase antibodies showed complete overlap.

CONCLUSIONS

Calcium-activated tissue transglutaminase autoantibody ELISA is highly accurate in detecting untreated celiac disease. Tissue transglutaminase seems to be the target self-antigen for endomysial antibodies.

In vivo targeting of intestinal and extraintestinal transglutaminase 2 by coeliac autoantibodies

BACKGROUND

IgA class serum autoantibodies against type 2 (tissue) transglutaminase (TG2) bind to both intestinal and extraintestinal normal tissue sections in vitro, eliciting endomysial, reticulin, and jejunal antibody reactions. It is not known whether similar binding also occurs in coeliac patients in vivo, and may thereby contribute to disease manifestations.

AIMS

To investigate intestinal and extraintestinal coeliac tissues for the presence of in vivo bound TG2 specific IgA and its relation to small intestinal mucosal atrophy.

PATIENTS

We investigated jejunal samples with normal villous morphology from 10 patients with developing coeliac disease who subsequently progressed to a flat lesion, from 11 patients with dermatitis herpetiformis, and from 12 non-coeliac controls. Six extrajejunal biopsy samples (liver, lymph node, muscle, appendix), obtained based on independent clinical indications from patients with active coeliac disease, were also studied.

METHODS

Double colour immunofluorescent studies for in situ IgA, TG2, and laminin were performed. IgA was eluted from tissue sections and tested for TG2 specificity by enzyme linked immunosorbent assay and indirect immunofluorescence.

RESULTS

IgA (in one IgA deficient case IgG) deposition on extracellularly located TG2 was detected in jejunal and extrajejunal specimens of all coeliac patients, and also in seven of 11 dermatitis herpetiformis patients, of whom two had no circulating endomysial antibodies. IgA eluted from extraintestinal coeliac tissues was targeted against TG2.

CONCLUSIONS

Coeliac IgA targets jejunal TG2 early in disease development even when endomysial antibodies are not present in the circulation. Extraintestinal target sites of coeliac IgA further indicate that humoral immunity may have a pathogenetic role.

Accuracy in Diagnosis of Celiac Disease Without Biopsies in Clinical Practice

BACKGROUND & AIMS

The guidelines of the European Society of Pediatric Gastroenterology, Hepatology, and Nutrition allow for diagnosis of celiac disease without biopsies in children with symptoms and levels of immunoglobulin A against tissue-transglutaminase (TGA-IgA) 10-fold or more the upper limit of normal (ULN), confirmed by detection of endomysium antibodies (EMA) and positivity for HLA-DQ2/DQ8. We performed a large, international prospective study to validate this approach.

METHODS

We collected data from consecutive pediatric patients (18 years or younger) on a gluten-containing diet who tested positive for TGA-IgA from November 2011 through May 2014, seen at 33 pediatric gastroenterology units in 21 countries. Local centers recorded symptoms; measurements of total IgA, TGA, and EMA; and histopathology findings from duodenal biopsies. Children were considered to have malabsorption if they had chronic diarrhea, weight loss (or insufficient gain), growth failure, or anemia. We directly compared central findings from 16 antibody tests (8 for TGA-IgA, 1 for TGA-IgG, 6 for IgG against deamidated gliadin peptides, and 1 for EMA, from 5 different manufacturers), 2 HLA-DQ2/DQ8 tests from 2 manufacturers, and histopathology findings from the reference pathologist. Final diagnoses were based on local and central results. If all local and central results were concordant for celiac disease, cases were classified as proven celiac disease. Patients with only a low level of TGA-IgA (threefold or less the ULN) but no other results indicating celiac disease were classified as no celiac disease. Central histo-morphometry analyses were performed on all other biopsies and cases were carefully reviewed in a blinded manner. Inconclusive cases were regarded as not having celiac disease for calculation of diagnostic accuracy. The primary aim was to determine whether the nonbiopsy approach identifies children with celiac disease with a positive predictive value (PPV) above 99% in clinical practice. Secondary aims included comparing performance of different serological tests and to determine whether the suggested criteria can be simplified.

RESULTS

Of 803 children recruited for the study, 96 were excluded due to incomplete data, low level of IgA, or poor-quality biopsies. In the remaining 707 children (65.1% girls; median age, 6.2 years), 645 were diagnosed with celiac disease, 46 were found not to have celiac disease, and 16 had inconclusive results. Findings from local laboratories of TGA-IgA 10-fold or more the ULN, a positive result from the test for EMA, and any symptom identified children with celiac disease (n = 399) with a PPV of 99.75 (95% confidence interval [CI], 98.61-99.99); the PPV was 100.00 (95% CI, 98.68-100.00) when only malabsorption symptoms were used instead of any symptom (n = 278). Inclusion of HLA analyses did not increase accuracy. Findings from central laboratories differed greatly for patients with lower levels of antibodies, but when levels of TGA-IgA were 10-fold or more the ULN, PPVs ranged from 99.63 (95% CI, 98.67-99.96) to 100.00 (95% CI, 99.23-100.00).

CONCLUSIONS

Children can be accurately diagnosed with celiac disease without biopsy analysis. Diagnosis based on level of TGA-IgA 10-fold or more the ULN, a positive result from the EMA tests in a second blood sample, and the presence of at least 1 symptom could avoid risks and costs of endoscopy for more than half the children with celiac disease worldwide. HLA analysis is not required for accurate diagnosis. Clinical Trial Registration no: DRKS00003555.

Endomysial antibody-negative coeliac disease: clinical characteristics and intestinal autoantibody deposits

BACKGROUND

Some patients with untreated coeliac disease are negative for serum endomysial autoantibodies (EmA) targeted against transglutaminase 2 (TG2).

AIMS

To evaluate the clinical and histological features of EmA-negative coeliac disease, and to examine whether EmA-equivalent autoantibodies against TG2 can be seen in the small-bowel mucosa when absent in serum.

PATIENTS

Serum EmA was studied in 177 biopsy-proved specimens from adult patients with coeliac disease. 20 patients with intestinal diseases served as non-coeliac controls; three had autoimmune enteropathy with villous atrophy.

METHODS

Clinical manifestations, small-bowel mucosal morphology, intraepithelial inflammation and TG2-specific extracellular immunoglobulin A (IgA) deposits were investigated in both serum EmA-negative and EmA-positive patients.

RESULTS

22 patients with IgA-competent coeliac disease were negative for serum EmA. Three of these had small-bowel lymphoma. Patients with EmA-negative coeliac disease were older, had abdominal symptoms more often, and the density of gammadelta+ intraepithelial lymphocytes in their intestinal mucosa was lower than in EmA-positive patients; otherwise the histology was similar. All serum EmA-negative patients with coeliac disease, but none of the disease controls, had gluten-dependent mucosal IgA deposits alongside TG2 in the small-bowel mucosal specimens. In vivo deposited IgA was shown to be TG2-specific by its ability to bind recombinant TG2.

CONCLUSIONS

Negative serum EmA might be associated with advanced coeliac disease. TG2-targeted autoantibodies were deposited in the small-bowel mucosa even when absent in serum. This finding can be used in the diagnosis of seronegative coeliac disease when the histology is equivocal. It may also be helpful in the differential diagnosis between autoimmune enteropathy and coeliac disease.

Antiendomysial and antihuman recombinant tissue transglutaminase antibodies in the diagnosis of coeliac disease: a biopsy-proven European multicentre study

OBJECTIVE

To investigate the value of serum antitissue transglutaminase IgA antibodies (IgA-TTG) and IgA antiendomysial antibodies (IgA-EMA) in the diagnosis of coeliac disease in cohorts from different geographical areas in Europe. The setting allowed a further comparison between the antibody results and the conventional small-intestinal histology.

METHODS

A total of 144 cases with coeliac disease [median age 19.5 years (range 0.9-81.4)], and 127 disease controls [median age 29.2 years (range 0.5-79.0)], were recruited, on the basis of biopsy, from 13 centres in nine countries. All biopsy specimens were re-evaluated and classified blindly a second time by two investigators. IgA-TTG were determined by ELISA with human recombinant antigen and IgA-EMA by an immunofluorescence test with human umbilical cord as antigen.

RESULTS

The quality of the biopsy specimens was not acceptable in 29 (10.7%) of 271 cases and a reliable judgement could not be made, mainly due to poor orientation of the samples. The primary clinical diagnosis and the second classification of the biopsy specimens were divergent in nine cases, and one patient was initially enrolled in the wrong group. Thus, 126 coeliac patients and 106 controls, verified by biopsy, remained for final analysis. The sensitivity of IgA-TTG was 94% and IgA-EMA 89%, the specificity was 99% and 98%, respectively.

CONCLUSIONS

Serum IgA-TTG measurement is effective and at least as good as IgA-EMA in the identification of coeliac disease. Due to a high percentage of poor histological specimens, the diagnosis of coeliac disease should not depend only on biopsy, but in addition the clinical picture and serology should be considered.

Autoantibody targeting of brain and intestinal transglutaminase in gluten ataxia

OBJECTIVE

To investigate the presence of autoantibody deposition against type 2 tissue transglutaminase (TG2; a reliable marker of the whole spectrum of gluten sensitivity) in the jejunal tissue and brain of patients with gluten ataxia and in control subjects.

METHODS

The authors evaluated jejunal biopsy samples from nine patients with gluten ataxia and seven patients with other causes of ataxia for the presence of TG2-related immunoglobulin deposits using double-color immunofluorescence. Autopsy brain tissue from one patient with gluten ataxia and one neurologically intact brain were also studied.

RESULTS

IgA deposition on jejunal TG2 was found in the jejunal tissue of all patients with gluten ataxia and in none of the controls. The intestinal IgA deposition pattern was similar to that seen in patients with overt and latent celiac disease and in those with dermatitis herpetiformis. Widespread IgA deposition around vessels was found in the brain of the patient with gluten ataxia but not the control brain. The deposition was most pronounced in the cerebellum, pons, and medulla.

CONCLUSIONS

Anti-tissue transglutaminase IgA antibodies are present in the gut and brain of patients with gluten ataxia with or without an enteropathy in a similar fashion to patients with celiac disease, latent celiac disease, and dermatitis herpetiformis but not in ataxia control subjects. This finding strengthens the contention that gluten ataxia is immune mediated and belongs to the same spectrum of gluten sensitivity as celiac disease and dermatitis herpetiformis.

Elevation of IgG antibodies against tissue transglutaminase as a diagnostic tool for coeliac disease in selective IgA deficiency

BACKGROUND

IgA serum autoantibodies against tissue transglutaminase (tTG) have an established diagnostic value in coeliac disease, and high efficacy tests are widely available for their detection. However, serological evaluation of IgA deficient subjects is still difficult.

AIMS

To evaluate the diagnostic potential of IgG class anti-tTG autoantibodies measured quantitatively using an enzyme linked immunosorbent assay (ELISA) compared with immunofluorescent detection of coeliac autoantibodies.

PATIENTS

We tested serum samples from 325 IgA deficient subjects, including 78 patients with coeliac disease, 73 disease controls, and 174 blood donors.

METHODS

IgG antibodies against human recombinant tTG were measured with an ELISA. IgG antiendomysium antibodies (EMA) were assayed by indirect immunofluorescence on human jejunum and appendix sections.

RESULTS

The IgG anti-tTG ELISA had a sensitivity of 98.7% and a specificity of 98.6%, and the correlation with IgG EMA titres was high (r(s)=0.91). One coeliac patient, initially negative in all autoantibody tests, displayed both IgG anti-tTG antibodies and IgG EMA during later gluten exposure. IgG anti-tTG antibodies and EMA titres showed significant decreases (p<0.001) in treated patients. The frequency of IgG anti-tTG autoantibody positivity was 9.8% among IgA deficient blood donors and 11 of the 12 positive subjects with known HLA-DQ haplotypes carried DQ2 or DQ8 alleles.

CONCLUSIONS

IgG anti-tTG and IgG EMA autoantibody tests are highly efficient in detecting coeliac disease in IgA deficient patients. The high prevalence of coeliac antibodies among symptom free IgA deficient blood donors who also carry coeliac-type HLA-DQ genes indicates that all IgA deficient persons should be evaluated for coeliac disease.

High prevalence of silent celiac disease in preschool children screened with IgA/IgG antiendomysium antibodies

BACKGROUND

Because of the different sensitivity and specificity of serologic tests, the search for silent celiac disease is usually performed with the combined or sequential use of several tests. Among these, the IgA-class endomysium antibody test has the highest specificity and positive predictive value, but it may overlook IgA-deficient patients.

METHODS

To test a new one-step screening approach, serum samples from 427 apparently healthy, 3- to 6-year-old Hungarian children were investigated for IgA-class and IgG-class endomysium antibodies using monkey esophagus and human jejunum as substrates.

RESULTS

Five new cases with flat mucosa were identified by strong endomysium antibody positivity and subsequent jejunal biopsy, yielding a celiac disease prevalence of 1:85. An additional child may have latent celiac disease (slight histologic changes at present). Two of the screening-detected celiac patients exhibited only IgG-class endomysium antibodies due to associated IgA-deficiency. Despite the young age of the screened population, antigliadin antibodies were positive in only three of the five celiac patients.

CONCLUSIONS

Prevalence of celiac disease in the study population was much higher than expected on the basis of antigliadin antibody-based studies. The screening system used detected celiac cases in which there was IgA-deficiency and those in which there was not and also those negative for antigliadin antibodies. The findings suggest the importance of the primary testing of autoantibodies in future celiac disease screening policies.

Transglutaminase 2 in human diseases

Transglutaminase 2 (TG2) is an inducible transamidating acyltransferase that catalyzes Ca(2+)-dependent protein modifications. In addition to being an enzyme, TG2 also serves as a G protein for several seven transmembrane receptors and acts as a co-receptor for integrin β1 and β3 integrins distinguishing it from other members of the transglutaminase family. TG2 is ubiquitously expressed in almost all cell types and all cell compartments, and is also present on the cell surface and gets secreted to the extracellular matrix via non-classical mechanisms. TG2 has been associated with various human diseases including inflammation, cancer, fibrosis, cardiovascular disease, neurodegenerative diseases, celiac disease in which it plays either a protective role, or contributes to the pathogenesis. Thus modulating the biological activities of TG2 in these diseases will have a therapeutic value.

Functional significance of five noncanonical Ca2+-binding sites of human transglutaminase 2 characterized by site-directed mutagenesis

The multifunctional tissue transglutaminase 2 (TG2) has a four-domain structure with several Ca(2+)-regulated biochemical activities, including transglutamylation and GTP hydrolysis. The structure of the Ca(2+)-binding form of the human enzyme is not known, and its Ca(2+)-binding sites have not been fully characterized. By mutagenesis, we have targeted its active site Cys, three sites based on homology to Ca(2+)-binding residues of epidermal transglutaminase and factor XIIIa (S1-S3), and two regions with negative surface potentials (S4 and S5). CD spectroscopy, antibody-binding assay and GTPase activity measurements indicated that the amino acid substitutions did not cause major structural alterations. Calcium-45 equilibrium dialysis and isothermal calorimetric titration showed that both wild-type and active site-deleted enzymes (C277S) bind six Ca(2+). Each of the S1-S5 mutants binds fewer than six Ca(2+), S1 is a strong Ca(2+)-binding site, and mutation of one site resulted in the loss of more than one bound Ca(2+), suggesting cooperativity among sites. All mutants were deficient in transglutaminase activity, and GTP inhibited remnant activities. Like those of the wild-type enzyme, the GTPase activities of the mutants were inhibited by Ca(2+), except in the case of the S4 and S5 mutants, which exhibited increased activity. TG2 is the major autoantigen in celiac disease, and testing the reactivity of mutants with autoantibodies from celiac disease patients revealed that S4 strongly determines antigenicity. It can be concluded that five of the Ca(2+)-binding sites of TG2 influence its transglutaminase activity, two sites are involved in the regulation of GTPase activity, and one determines antigenicity for autoantibodies in celiac patients.

Coeliac disease-specific autoantibodies targeted against transglutaminase 2 disturb angiogenesis

Coeliac disease is characterized by immunoglobulin-A (IgA)-class autoantibodies targeted against transglutaminase 2 (TG2), a multi-functional protein also with a role in angiogenesis. These antibodies are present in patient serum but are also found bound to TG2 below the epithelial basement membrane and around capillaries in the small intestinal mucosa. Based on these facts and the information that the mucosal vasculature of coeliac patients on a gluten-containing diet is disorganized, we studied whether the coeliac disease-specific autoantibodies targeted against TG2 would disturb angiogenesis. The effects of coeliac disease-specific autoantibodies on in vitro angiogenesis were studied in angiogenic cell cultures. The binding of the antibodies to cells, endothelial sprouting, migration of both endothelial and vascular mesenchymal cells, the integrity of the actin cytoskeleton in both cell types and the differentiation of vascular mesenchymal cells were recorded. In vitro, IgA derived from coeliac disease patients on a gluten-containing diet binds to surface TG2 on endothelial and vascular mesenchymal cells and this binding can be inhibited by the removal of TG2. In addition, coeliac disease-specific autoantibodies targeting TG2 disturb several steps of angiogenesis: endothelial sprouting and the migration of both endothelial and vascular mesenchymal cells. Furthermore, the autoantibodies cause disorganization of the actin cytoskeleton in both capillary cell types that account most probably for the defective cellular migration. We conclude that coeliac disease-specific autoantibodies recognizing TG2 inhibit angiogenesis in vitro. This disturbance of the angiogenic process could lead in vivo to the disruption of the mucosal vasculature seen in coeliac disease patients on a gluten-containing diet.

Increased mucosal expression of Toll-like receptor (TLR)2 and TLR4 in coeliac disease

OBJECTIVES

The dysregulation of adaptive immunity is extensively investigated in celiac disease (CD). Recent data also suggest, however, the implication of innate immunity in CD. Toll-like receptors (TLRs) play a central role in the initiation or maintenance of innate immune responses. The aim of this study was to characterise the expression of TLR2, TLR3, and TLR4 in duodenal biopsy samples taken from children with CD and from controls.

PATIENTS AND METHODS

Duodenal biopsy specimens were collected from 16 children with untreated CD, 9 children with treated CD, and 10 controls. The mRNA expression of TLR2, TLR3, and TLR4 was determined by semiquantitative reverse transcription-polymerase chain reaction. Protein levels of TLRs were determined by Western blot.

RESULTS

We found higher TLR2 and TLR4 mRNA expression and protein levels in the duodenal mucosa of children with treated CD and untreated CD compared with controls. TLR2 and TLR4 mRNA expression and protein levels were even higher in the duodenal mucosa of children with treated CD than in untreated CD. TLR3 mRNA expression was increased in the duodenal mucosa of children with treated CD compared with untreated CD and controls. We were able to detect TLR3 protein only in the biopsy specimens of treated patients with CD.

CONCLUSIONS

The alteration of TLR2 and TLR4 expression in the duodenal mucosa of patients with CD supports the potential implication of innate immune system in the pathomechanism of this disease.

Missing endomysial and reticulin binding of coeliac antibodies in transglutaminase 2 knockout tissues

BACKGROUND

Autoantibodies against transglutaminase 2 (TG2) are thought to be responsible for the endomysial (EMA), reticulin (ARA), and jejunal antibody (JEA) tissue binding of serum samples from coeliac patients but the exclusive role of TG2 in these staining patterns has not yet been established.

AIMS

To evaluate whether antigens other than TG2 contribute to EMA/ARA/JEA reactions.

PATIENTS

Serum samples from 61 EMA/ARA/JEA positive untreated patients with coeliac disease, 40 dermatitis herpetiformis patients, and 34 EMA/ARA/JEA negative non-coeliac controls were tested.

METHODS

TG2 knockout (TG2-/-) and wild-type mouse oesophagus, jejunum, liver, and kidney sections, and TG2-/- sections coated with human recombinant TG2 were used as substrates in single and double immunofluorescent studies for patient IgA binding and tissue localisation of TG2, fibronectin, actin, and calreticulin.

RESULTS

None of the patient serum samples elicited EMA, ARA, or JEA binding in TG2-/- morphologically normal tissues. In contrast, 96 of 101 gluten sensitive patient samples (95%) reacted with wild-type mouse tissues and all 101 reacted in EMA/ARA/JEA patterns with TG2-/- mouse tissues coated with human TG2. Serum IgA binding to TG2-/- smooth muscle cells was observed in low titres in 31.1%, 27.5%, and 20.5%, and to TG2-/- epithelium in 26.3%, 5.0%, and 8.8% of coeliac, dermatitis herpetiformis, and control samples, respectively. These positivities partly colocalised with actin and calreticulin but not with TG2 or fibronectin.

CONCLUSIONS

EMA/ARA/JEA antibody binding patterns are exclusively TG2 dependent both in coeliac and dermatitis herpetiformis patients. Actin antibodies are responsible for some positivities which are not part of the EMA/ARA/JEA reactions.

Self transglutaminase-based rapid coeliac disease antibody detection by a lateral flow method

BACKGROUND

The conventional coeliac disease antibody tests require patient's sera, and are laborious and time-consuming.

AIM

To evaluate a newly developed rapid whole blood test in coeliac disease antibody detection, and its suitability for office use.

METHODS

Endogenous tissue transglutaminase found in red blood cells in a whole blood fingertip or venous sample is liberated upon haemolysis and complexes with tissue transglutaminase antibodies, if present. The complexes, captured by a lateral flow system, are visualized within 5 min. Stored samples from 121 untreated, 106 treated coeliac disease patients and 107 controls were evaluated and compared with serum endomysium and tissue transglutaminase antibody tests and histology; 150 patients were prospectively tested on site in the doctor's office.

RESULTS

The rapid test showed sensitivity (96.7%) comparable with the serum endomysium and tissue transglutaminase antibody tests from stored samples; specificity was slightly lower (93.5%). When tested on site the results were concordant in 96.7% of cases compared with endomysium and tissue transglutaminase antibody results. The test recognized the disappearance of tissue transglutaminase antibodies on a gluten-free diet.

CONCLUSIONS

The self tissue transglutaminase-based rapid test can be easily carried out from a fingertip blood sample on site in the physician's office for both coeliac disease case finding and dietary monitoring purposes.

Epithelial transport and deamidation of gliadin peptides: a role for coeliac disease patient immunoglobulin A

In coeliac disease, the intake of dietary gluten induces small-bowel mucosal damage and the production of immunoglobulin (Ig)A class autoantibodies against transglutaminase 2 (TG2). We examined the effect of coeliac patient IgA on the apical-to-basal passage of gluten-derived gliadin peptides p31-43 and p57-68 in intestinal epithelial cells. We demonstrate that coeliac IgA enhances the passage of gliadin peptides, which could be abolished by inhibition of TG2 enzymatic activity. Moreover, we also found that both the apical and the basal cell culture media containing the immunogenic gliadin peptides were able to induce the proliferation of deamidation-dependent coeliac patient-derived T cells even in the absence of exogenous TG2. Our results suggest that coeliac patient IgA could play a role in the transepithelial passage of gliadin peptides, a process during which they might be deamidated.

Transglutaminase 2 is expressed and active on the surface of human monocyte-derived dendritic cells and macrophages

The multifunctional enzyme, transglutaminase 2 (TG2), can be found intracellularly, in the extracellular matrix and on the cell surface. Cell surface TG2 (csTG2) could not be detected by TG2-specific antibodies or autoantibodies on immunocompetent cells. A supposedly csTG2-specific antibody, 6B9, was recently shown to actually react with CD44. Though the importance of TG2-mediated deamidation of gluten in the pathogenesis of celiac disease has been well recognized, it is not known in which intestinal cells or cell compartment the deamidation occurs. Duodenal dendritic cells (DCs) can be directly involved in gluten-reactive T-cell activation. Here we use blood monocyte-derived dendritic cells (iDC) and macrophages (MPhi) as a model for intestinal antigen-presenting cells (APCs) and show that they contain large amounts of TG2. We found that TG100, a commercial TG2-specific monoclonal antibody can recognize TG2 on the surface of these cells, that is monocyte-derived APCs express surface-associated TG2. TG2 expression was found on the surface of individual tunica propria cells in frozen small bowel tissue sections from both normal and celiac subjects. We also demonstrate that the pool of TG2 on the surface of iDCs can be catalytically active, hence it might directly be involved in the deamidation of gliadin peptides. Bacterial lipopolysaccharide (LPS) increased the level of TG2 on the surface of maturing DCs, supporting the hypothesis that an unspecific inflammatory process in the gut may expose more transglutaminase activity.

Coeliac autoantibodies can enhance transamidating and inhibit GTPase activity of tissue transglutaminase: Dependence on reaction environment and enzyme fitness

Modification of the enzymatic functions of tissue transglutaminase (TG2) by anti-TG2 autoantibodies may play a role in manifestations of coeliac disease. Our aim was to evaluate the effect of coeliac autoantibodies on reactions catalysed by TG2 by a systematic biochemical approach, and in relation to observed clinical presentation type. Coeliac antibodies did not have significant inhibitory effect on transamidation/deamidation activity of TG2 as measured by amine-incorporation into solid and immobilised casein and by ultraviolet kinetic assay. In contrast, immunoglobulins from patients with severe malabsorption enhanced the reaction velocity to 105.4-242.2%. This activating effect was dose-dependent, most pronounced with immobilised glutamine-acceptor substrates, and correlated inversely with the basal specific activity of the enzyme and with dietary treatment. A similar activation could be demonstrated also with the TG2-specific fraction of autoantibodies and in transamidation activity assays which use fibronectin-bound TG2 and thereby mimic in vivo conditions. These results suggest that coeliac antibodies may stabilise the enzyme in a catalytically advantageous conformation. GTPase activity of TG2 decreased to 67.0-73.4% in the presence of antibodies raising the possibility that inhibition of GTPase activity may affect cellular signalling in case coeliac autoantibodies would reach intracellular compartments.

Tissue transglutaminase is the target in both rodent and primate tissues for celiac disease-specific autoantibodies

BACKGROUND

Endomysial antibodies have recently been shown to react with tissue transglutaminase. This study was undertaken to investigate whether the tissue distribution of transglutaminase is also compatible with reticulin, jejunal, and fibroblast autoantibody binding patterns.

METHODS

Sera from patients with and without celiac disease, monoclonal tissue transglutaminase antibodies, and sera from mice parenterally immunized against commercially available tissue transglutaminase, transglutaminase complexed with gliadin, or gliadin were used in indirect immunofluorescence and double-staining studies using both rodent and primate tissues as substrates. Also, antibody competition, affinity chromatography, and potassium thiocyanate extraction studies were undertaken.

RESULTS

Tissue transglutaminase antibody binding patterns were identical with the extracellular binding patterns seen with celiac patient sera. Human umbilical cord-derived fibroblasts exhibited both cytoplasmic and extracellular matrix staining. Double staining with patients' sera and tissue transglutaminase antibodies showed complete overlapping. Tissue transglutaminase effectively absorbed reticulin-endomysial antibodies from celiac sera, and patients' sera blocked the staining of the monoclonal tissue transglutaminase antibodies. Potassium thiocyanate extraction abolished the staining patterns, but they were elicited again after readdition of tissue transglutaminase.

CONCLUSIONS

Reticulin, endomysial, and jejunal antibodies detect transglutaminase in both rodent and primate tissues, indicating that these tissue autoantibodies are identical.

Coeliac disease case finding and diet monitoring by point-of-care testing

BACKGROUND

Immunoglobulin A class transglutaminase autoantibodies are highly predictive markers of active coeliac disease, a disorder difficult to recognize solely on clinical grounds.

AIMS

To develop and evaluate a simple rapid test for point-of-care detection of coeliac autoantibodies.

METHODS

The novel whole blood test utilizes the patient's endogenous transglutaminase in red blood cells for detection of transglutaminase-specific immunoglobulin A antibodies present in the blood sample, with normal plasma immunoglobulin A detection as positive test control. We evaluated 284 patients under suspicion of coeliac disease and undergoing jejunal biopsy, and 263 coeliac patients on a gluten-free diet, 383 being tested prospectively in a point-of-care setting. Results were compared with histology, conventional serum autoantibody results and dietary adherence.

RESULTS

The rapid test showed 97% sensitivity and 97% specificity for untreated coeliac disease, and identified all immunoglobulin A-deficient samples. Point-of-care testing found new coeliac cases as efficiently as antibody tests in laboratory. Coeliac autoantibodies were detected onsite in 21% of treated patients, while endomysial and transglutaminase antibodies were positive in 20% and 19%, respectively. The positivity rate correlated with dietary lapses and decreased on intensified dietary advice given upon positive point-of-care test results.

CONCLUSIONS

Point-of-care testing was accurate in finding new coeliac cases and helped to identify and decrease dietary non-compliance.

S2k guidelines (consensus statement) for diagnosis and therapy of dermatitis herpetiformis initiated by the European Academy of Dermatology and Venereology (EADV)

INTRODUCTION

Dermatitis herpetiformis (DH) is a chronic, pruritic, gluten-induced skin disorder characterized by subepidermal granular IgA deposition and a variable degree of enteropathy identical to that seen in coeliac disease. So far, there has been no European consensus about the management of DH.

METHODS

The guidelines were created by small subgroups of a guideline committee consisting of 26 specialists from various medical fields and one patients' representative. The members of the committee then discussed the guidelines and voted for the final version at two consensus meetings. The guidelines were developed under the support of the European Academy of Dermatology and Venereology (EADV) and in collaboration with the European Dermatology Forum (EDF).

RESULTS

The guidelines summarize evidence-based and expert-based recommendations (S2 level) for the management of DH (see Appendix).

CONCLUSION

These guidelines will improve the quality of management of DH and support dermatologists in their diagnostic and therapeutic decisions.

Performance of a new rapid whole blood coeliac test in adult patients with low prevalence of endomysial antibodies

BACKGROUND

In coeliac disease endomysial and transglutaminase autoantibodies are directed against the human autoantigen, transglutaminase. The conventional coeliac antibody tests are performed from serum samples in centralized laboratories.

AIMS

To evaluate a rapid and easy immunoglobulin A-class whole blood point-of-care test and its commercial application, the Biocard test, in coeliac autoantibody detection.

METHODS

In the whole blood point-of-care test transglutaminase is liberated from the red blood cells by haemolysis. Transglutaminase antibodies, if present, complex with the liberated antigen, and are visualized. Altogether 51 biopsy-proven untreated coeliac adult patients, 48 of the same patients after treatment, and 36 controls were tested. The point-of-care test results were compared with serum endomysial and transglutaminase antibody and Biocard test results and histology.

RESULTS

The whole blood point-of-care test was as sensitive (82%) as the serum endomysium test (80%) in detecting untreated coeliac disease while the serum transglutaminase antibody test was superior (88%). The tests had 100% specificity. A positive point-of-care test result seroconverted or the test reaction weakened in 90% of the treated coeliac patients. Biocard test-positive were 22 of the 24 tested untreated coeliac patients. Biocard test-negative were 15 of 19 controls.

CONCLUSIONS

The whole blood rapid tests are as reliable as the conventional serological tests in detecting untreated coeliac disease and in coeliac disease diet monitoring.

Intestinal anti-transglutaminase 2 immunoglobulin A deposits in children at risk for coeliac disease (CD): data from the PreventCD study

In coeliac disease (CD), anti-tissue transglutaminase 2 immunoglobulin (Ig)A antibodies (anti-TG2) are produced and deposited in the intestine. PreventCD (www.preventcd.com) is a European multi-centre study, which investigates the influence of infant nutrition and that of genetic, immunological and other environmental factors on the risk of developing CD. The aim of the current study was to evaluate the appearance of intestinal anti-TG2 deposits in very early intestinal biopsies from at-risk infants and their predictive value for villous atrophy. Sixty-five small bowel biopsies, performed in 62 children, were investigated for the presence of intestinal anti-TG2 extracellular IgA deposits by using double immunofluorescence. The biopsies were performed in the presence of elevated serum levels of CD-associated antibodies and/or symptoms suggesting disease. Deposits of anti-TG2 IgA were present in 53 of 53 CD patients and three of three potential CD patients. In potential CD patients, mucosal deposits showed a patchy distribution characterized by some areas completely negative, whereas active CD patients had uniformly present and evident mucosal deposits. Only one of six patients without CD (negative for serum anti-TG2 and with normal mucosa) had intestinal deposits with a patchy distribution and a weak staining. Two of the 53 CD patients received a definitive diagnosis of CD after a second or third biopsy; mucosal deposits of anti-TG2 IgA were evaluated in all samples. Before developing villous atrophy, both patients had anti-TG2 deposits in normal mucosal architecture, antibodies in one patient being absent in serum. We demonstrated that in CD the intestinal deposits of anti-TG2 are a constant presence and appear very early in the natural history of disease.

Diagnostic significance of HLA-DQ typing in patients with previous coeliac disease diagnosis based on histology alone

BACKGROUND

Coeliac disease is strongly associated with human leukocyte antigen (HLA)-DQ2 or DQ8 genotypes. The diagnosis is based on demonstrating crypt-hyperplastic villous atrophy, endomysial or transglutaminase antibodies and correlation of disease activity with gluten intake.

AIM

To evaluate the clinical utility of HLA-DQ typing, when coeliac disease diagnosis had previously been established solely by histology.

METHODS

HLA-DQ alleles, endomysial and transglutaminase antibodies were investigated and histology slides reviewed in 70 patients diagnosed 2-25 years earlier by small-intestinal biopsy but without measuring endomysial or transglutaminase antibodies. Patients without DQ2 or DQ8 or without unequivocal villous atrophy were followed-up on free diet by using serology and biopsies.

RESULTS

All 40 endomysial/transglutaminase antibodies positive patients carried DQ2 or DQ8, and 39 of them had severe villous atrophy. Only 56% of patients without endomysial or transglutaminase antibodies positivity had DQ2 or DQ8 (P < 0.001). Seropositivity and relapse developed in 4 of 11 DQ2 positive but in none of 15 DQ2 and DQ8 negative patients on long-term gluten exposure.

CONCLUSIONS

Coeliac disease diagnosis based solely on histology is not always reliable. HLA-DQ typing is important in identifying DQ2 and DQ8 negative subjects who need revision of their diagnosis, but it does not have additive diagnostic value if endomysial positivity is already known.

Prospective significance of antiendomysium antibody positivity in subsequently verified celiac disease

BACKGROUND

In order to assess their long-term predictability for the diagnosis of celiac disease, antiendomysium antibody results were compared with the outcome of the Interlaken diagnostic process.

METHODS

Prospective gluten challenge was performed in 153 children with previously diagnosed flat small-intestine mucosa. In 90 patients (Group A), endomysium antibodies were initially positive, in seven (Group B) they were negative, and 56 patients (Group C) had no initial serological results. In IgA-deficient persons, IgG antibodies were also assayed, both by the immunofluorescent method.

RESULTS

Histological relapse rates were 100% (90/90), 14.3% (1/7), and 76.8% (43/56), p < 0.001, in Groups A, B, and C, respectively. Each patient with relapse also exhibited endomysium antibody positivity during the challenge. Patients in whom celiac disease could be finally ruled out remained consistently endomysium-antibody negative. The celiac disease patient in Group B had severe secondary immunoglobulin deficiency at entry, which explained the initial negativity. Diagnosis based on antiendomysium antibody positivity and flat mucosa gave a higher applicability (92.8 vs. 50.3%) and reliability (relapse rate 100 vs. 89.6%) than the 1990 European Society of Paediatric Gastroenterology and Nutrition (ESPGAN) criteria among these patients.

CONCLUSIONS

Endomysium antibody positivity at presentation has been found to be as useful as gluten challenge in the diagnosis of celiac disease, even in patients under the age of 2 years. Challenge is still advisable in patients with a flat small intestinal mucosa when antiendomysium antibody results are negative or have not been done, as among these patients significantly lower relapse rates were found.