Guinea pig transglutaminase immunolinked assay does not predict coeliac disease in patients with chronic liver disease

Prevalence of celiac disease in patients with liver diseases: a systematic review and meta-analyses

OBJECTIVES

A subset of patients with celiac disease (CeD) have liver involvement in the form of hypertransaminasemia, liver cirrhosis and autoimmune hepatitis. We conducted a systematic review with meta-analyses to determine pooled prevalence of CeD in patients with cryptogenic cirrhosis, all-cause cirrhosis, cryptogenic hypertransaminasemia, and all-cause hypertransaminasemia.

METHODS

We searched PubMed and EMBASE up to January 2022. Cross-sectional, case-control and prospective cohort studies performing serological tests and/or intestinal biopsy for CeD on patients with cryptogenic cirrhosis, all-cause cirrhosis, cryptogenic hypertransaminasemia and all-cause hypertransaminasemia were included, to calculate pooled estimates of seroprevalence and prevalence of biopsy-confirmed CeD in these four groups.

RESULTS

Of 6,871 articles screened, 20 articles were included finally in three meta-analyses for cryptogenic cirrhosis, all-cause cirrhosis and cryptogenic hypertransaminasemia. For the all-cause hypertransaminasemia group, a qualitative review of four studies was done instead of a meta-analysis, due to significant differences in studies. The pooled prevalence (95%CI) of biopsy-confirmed CeD, in cryptogenic cirrhosis was 4.6%(2.2-7.5%) while pooled prevalence of biopsy-confirmed CeD in all-cause cirrhosis was 0.8%(0-3.4%). Pooled prevalence of biopsy-confirmed CeD in cryptogenic hypertransaminasemia was 5.7%(3.2-8.8%).

CONCLUSIONS

Nearly one in 20 patients each with cryptogenic cirrhosis and cryptogenic hypertransaminasemia have CeD, hence they should both be considered high-risk groups for CeD. While prevalence of CeD in all-cause cirrhosis is similar to that in general population, it may be worth screening them for CeD as liver pathology has potential for reversal in them.

Positive tissue transglutaminase antibodies with negative endomysial antibodies: Unresolved issues in diagnosing celiac disease

BACKGROUND

The serological screening for celiac disease (CD) is currently based on the detection of anti-transglutaminase (tTG) IgA antibodies, subsequently confirmed by positive endomysial antibodies (EMA). When an anti-tTG IgA positive/EMA IgA negative result occurs, it can be due either to the lower sensitivity of the EMA test or to the lower specificity of the anti-tTG test. This study aimed at verifying how variation in analytical specificity among different anti-tTG methods could account for this discrepancy.

METHODS

A total of 130 consecutive anti-tTG IgA positive/EMA negative samples were collected from the local screening routine and tested using five anti-tTG IgA commercial assays: two chemiluminescence methods, one fluoroimmunoenzymatic method, one immunoenzymatic method and one multiplex flow immunoassay method.

RESULTS

Twenty three/130 (17.7%) patients were diagnosed with CD. In the other 107 cases a diagnosis of CD was not confirmed. The overall agreement among the five anti-tTG methods ranged from 28.5% to 77.7%. CD condition was more likely linked to the positivity of more than one anti-tTG IgA assay (monopositive = 2.5%, positive with ≥ three methods = 29.5%; p = 0.0004), but it was not related to anti-tTG IgA antibody levels (either positive or borderline; p = 0.5).

CONCLUSIONS

Patients with positive anti-tTG/negative EMA have a low probability of being affected by CD. Given the high variability among methods to measure anti-tTG IgA antibodies, anti-tTG-positive/EMA-negative result must be considered with extreme caution. It is advisable that the laboratory report comments on any discordant results, suggesting to consider the data in the proper clinical context and to refer the patient to a CD reference center for prolonged follow up.

Anti tissue transglutaminase antibody in idiopathic autoimmune haemolytic anemia

BACKGROUND

In idiopathic autoimmune haemolytic anaemia (AIHA haemolytic antibodies are directed to every type of red cellsWestern blot studies have shown antibody positivity towards red cell anion channel complex which also includes band 4.2 a protein with similarities to tissue trans glutaminase.

OBJECTIVE

Evaluation of AIHA for anti tissue transglutaminase antibody (Anti tTG).

MATERIALS & METHODS

Twenty three AIHA patients were tested along with routine hamatogical work up, for a series of auto antibodies and red cell eluates and serum from the patents were tested against solubilised group O red cell ghosts on western blot. Other ancillary investigations were done to rule out complications and secondary causes of haemolysis.

RESULTS

11/23 patients (48%) were positive for anti tTG, Four, 3 and 8,7 patients were positive for anti thyroid, anti b2 glycoprotein, lupus anticoagulant and ANA respectively. One patient with anti tTG had biopsy proven celiac disease. Three patient developed DVT and all of them were lupus anticoagulant as well as b2 gp-1 antibody positive.17 had become Coombs test negative on treatment while 21/23 had positive western blot test.

DISCUSSION & CONCLUSION

There is strong association of anti tTG antibody with idiopathic AIHA. Aetiological association of this finding needs exploration.

Prevalence and clinical significance of IgA anti-tissue transglutaminase antibodies in patients with chronic liver disease

BACKGROUND AND AIM

Celiac disease is a multi-systemic disease, which can affect any organ system including liver. However, the prevalence of celiac disease and the sensitivity and specificity of anti-tissue transglutaminase (anti-tTG) in diagnosing celiac disease in patients with cirrhosis of liver is not well established.

METHODS

We screened a cohort of patients with chronic liver disease for an associated diagnosis of celiac disease. Anti-tTG was carried out in all patients, and those with a high value were subjected to duodenal biopsy for histological confirmation. In patients where biopsy was contraindicated or refused, anti-endomysial antibody (anti-EMA) was tested.

RESULTS

Of a total of 595 patients with chronic liver disease, high levels of anti-tTG were noted in 150 (25.2%) patients, and celiac disease was diagnosed in 14 patients (2.4%). Celiac autoimmunity (high levels of both anti-tTG and anti-EMA) was noted in seven patients (1.2%).

CONCLUSIONS

Although a large number of cirrhotic patients have high levels of anti-tTG, duodenal histology and/or anti-EMA is normal in majority of these patients. This suggests high false positivity of anti-tTG in patients with cirrhosis and highlights the need of duodenal biopsy for histological confirmation of the diagnosis of celiac disease.

Overview of biomarkers for diagnosis and monitoring of celiac disease

Among the adverse reactions caused by wheat, celiac disease (CD) is the longest studied and best-known pathology. The more recently defined non-celiac gluten sensitivity (NCGS) presents with symptoms which are often indistinguishable from CD. Diagnosis of CD is based on serologic, molecular, and bioptic testing. The IgA anti-transglutaminase (tTG) test is considered highly important, as it shows high sensitivity and specificity and its levels correlate to the degree of intestinal damage. Small bowel biopsy can be avoided in symptomatic patients with IgA anti-tTG levels above 10× the manufacturer's cut-off. Recently, tests of anti-deamidated peptides of gliadin (DGP) have replaced classic anti-native gliadin (AGA) tests. DGP assays have a considerably higher diagnostic accuracy than AGA assays, especially in the IgG class, and can replace anti-tTG tests in patients with selective IgA deficiency. The combination of IgG anti-DGP plus IgA anti-tTG assays show greater sensitivity than a single test, with very high specificity. EMA tests have great diagnostic accuracy but are not recommended by all the latest guidelines because they are observer dependent. Biopsy must still be considered the gold standard for CD diagnosis. HLA-DQ genotyping can be used to screen asymptomatic children and in cases of histology/serology disagreement. About half of NCGS patients are DQ2 positive and have IgG AGA. To diagnose NCGS, first CD and wheat allergy must be excluded; then the wheat dependence of symptoms must be verified by a gluten-free diet and subsequent gluten challenge.

Investigation into celiac disease in Indian patients with portal hypertension

BACKGROUND

There is limited data on celiac disease in patients with cryptogenic cirrhosis or idiopathic noncirrhotic intrahepatic portal hypertension (NCIPH). Our objective was to evaluate for celiac disease in patients with portal hypertension in India.

METHODS

Consecutive patients with portal hypertension having cryptogenic chronic liver disease (cases) and hepatitis B- or C-related cirrhosis (controls) were prospectively enrolled. We studied tissue transglutaminase (tTG) antibody and duodenal histology in study patients.

RESULT

Sixty-one cases (including 14 NCIPH patients) and 59 controls were enrolled. Celiac disease was noted in six cases (including two NCIPH patients) as compared to none in controls. In a significant proportion of the remaining study subjects, duodenal biopsy showed villous atrophy, crypt hyperplasia, and lamina propria inflammation, not accompanied by raised intraepithelial lymphocytes (IELs); this was seen more commonly in cases as compared to controls. An unexpectedly high rate of tTG antibody positivity was seen in study subjects (66 %) of cases as compared to 29 % in controls (p-value < 0.001), which could indicate false-positive test result.

CONCLUSION

In this study, 10 % of patients with unexplained portal hypertension (cryptogenic chronic liver disease) had associated celiac disease. In addition, an unexplained enteropathy was seen in a significant proportion of study patients, more so in patients with cryptogenic chronic liver disease. This finding warrants further investigation.

Prevalence of serum celiac antibody in patients with IBD in Japan

BACKGROUND

Although the incidence of inflammatory bowel diseases (IBD) in Japan has increased, the prevalence of celiac disease is considered very low with the lowest genetic disposition. IBD is reported as the most common comorbidity because of the high positive rate of serological celiac markers. The aim of this study was to examine the current incidence of celiac disease, especially in IBD patients in Japan, where both wheat consumption and incidence of IBD have increased.

METHODS

A total of 172 patients with IBD and 190 controls in Japan were screened for serum antibody of tissue transglutaminase and deaminated gliadin peptide. In sero-positive patients, HLA testing and upper gastrointestinal endoscopy with duodenal biopsy was performed. Some of the sero-positive patients started a gluten-restricted or unrestricted diet, and serological change was determined.

RESULTS

The positivity of both serum antibodies was significantly higher in IBD and correlated with disease activity. However, no biopsy-defined or HLA-defined true celiac disease was found. A decrease in serum antibody titers was observed with a gluten-restricted diet.

CONCLUSIONS

Despite the increased incidence of IBD and high positivity for serum celiac antibody in Japanese IBD patients, no true-positive celiac disease was noted, suggesting the presence of gluten intolerance in these populations.

Hepatobiliary manifestations of gastrointestinal and nutritional disorders

Hepatobiliary manifestations of gastrointestinal and nutritional disorders can occur as part of the clinical spectrum of the underlying disease or as a consequence of the treatment of the disease. This article reviews aspects of pathogenesis, diagnosis, and management of hepatobiliary manifestations associated with a selection of gastrointestinal and nutritional disorders including inflammatory bowel disease, celiac disease, Whipple's disease, and parenteral nutrition associated disorders.

Clinical utility of serologic testing for celiac disease in ontario: an evidence-based analysis

OBJECTIVE OF ANALYSIS: The objective of this evidence-based evaluation is to assess the accuracy of serologic tests in the diagnosis of celiac disease in subjects with symptoms consistent with this disease. Furthermore the impact of these tests in the diagnostic pathway of the disease and decision making was also evaluated. CELIAC DISEASE: Celiac disease is an autoimmune disease that develops in genetically predisposed individuals. The immunological response is triggered by ingestion of gluten, a protein that is present in wheat, rye, and barley. The treatment consists of strict lifelong adherence to a gluten-free diet (GFD). Patients with celiac disease may present with a myriad of symptoms such as diarrhea, abdominal pain, weight loss, iron deficiency anemia, dermatitis herpetiformis, among others.

SEROLOGIC TESTING IN THE DIAGNOSIS CELIAC DISEASE

There are a number of serologic tests used in the diagnosis of celiac disease. Anti-gliadin antibody (AGA)Anti-endomysial antibody (EMA)Anti-tissue transglutaminase antibody (tTG)Anti-deamidated gliadin peptides antibodies (DGP)Serologic tests are automated with the exception of the EMA test, which is more time-consuming and operator-dependent than the other tests. For each serologic test, both immunoglobulin A (IgA) or G (IgG) can be measured, however, IgA measurement is the standard antibody measured in celiac disease.

DIAGNOSIS OF CELIAC DISEASE

According to celiac disease guidelines, the diagnosis of celiac disease is established by small bowel biopsy. Serologic tests are used to initially detect and to support the diagnosis of celiac disease. A small bowel biopsy is indicated in individuals with a positive serologic test. In some cases an endoscopy and small bowel biopsy may be required even with a negative serologic test. The diagnosis of celiac disease must be performed on a gluten-containing diet since the small intestine abnormalities and the serologic antibody levels may resolve or improve on a GFD. Since IgA measurement is the standard for the serologic celiac disease tests, false negatives may occur in IgA-deficient individuals.

INCIDENCE AND PREVALENCE OF CELIAC DISEASE

The incidence and prevalence of celiac disease in the general population and in subjects with symptoms consistent with or at higher risk of celiac disease based on systematic reviews published in 2004 and 2009 are summarized below.

INCIDENCE OF CELIAC DISEASE IN THE GENERAL POPULATION

ADULTS OR MIXED POPULATION: 1 to 17/100,000/year

CHILDREN

2 to 51/100,000/yearIn one of the studies, a stratified analysis showed that there was a higher incidence of celiac disease in younger children compared to older children, i.e., 51 cases/100,000/year in 0 to 2 year-olds, 33/100,000/year in 2 to 5 year-olds, and 10/100,000/year in children 5 to 15 years old.

PREVALENCE OF CELIAC DISEASE IN THE GENERAL POPULATION

The prevalence of celiac disease reported in population-based studies identified in the 2004 systematic review varied between 0.14% and 1.87% (median: 0.47%, interquartile range: 0.25%, 0.71%). According to the authors of the review, the prevalence did not vary by age group, i.e., adults and children.

PREVALENCE OF CELIAC DISEASE IN HIGH RISK SUBJECTS

Type 1 diabetes (adults and children): 1 to 11%AUTOIMMUNE THYROID DISEASE: 2.9 to 3.3%FIRST DEGREE RELATIVES OF PATIENTS WITH CELIAC DISEASE: 2 to 20% PREVALENCE OF CELIAC DISEASE IN SUBJECTS WITH SYMPTOMS CONSISTENT WITH THE DISEASE: The prevalence of celiac disease in subjects with symptoms consistent with the disease varied widely among studies, i.e., 1.5% to 50% in adult studies, and 1.1% to 17% in pediatric studies. Differences in prevalence may be related to the referral pattern as the authors of a systematic review noted that the prevalence tended to be higher in studies whose population originated from tertiary referral centres compared to general practice.

RESEARCH QUESTIONS

What is the sensitivity and specificity of serologic tests in the diagnosis celiac disease?What is the clinical validity of serologic tests in the diagnosis of celiac disease? The clinical validity was defined as the ability of the test to change diagnosis.What is the clinical utility of serologic tests in the diagnosis of celiac disease? The clinical utility was defined as the impact of the test on decision making.What is the budget impact of serologic tests in the diagnosis of celiac disease?What is the cost-effectiveness of serologic tests in the diagnosis of celiac disease?

METHODS

LITERATURE SEARCH

A literature search was performed on November 13(th), 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1(st) 2003 and November 13(th) 2010. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist, then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology. Inclusion Criteria Inclusion CriteriaExclusion CriteriaStudies that evaluated diagnostic accuracy, i.e., both sensitivity and specificity of serology tests in the diagnosis of celiac disease.Study population consisted of untreated patients with symptoms consistent with celiac disease.Studies in which both serologic celiac disease tests and small bowel biopsy (gold standard) were used in all subjects.Systematic reviews, meta-analyses, randomized controlled trials, prospective observational studies, and retrospective cohort studies.At least 20 subjects included in the celiac disease group.English language.Human studies.Studies published from 2000 on.Clearly defined cut-off value for the serology test. If more than one test was evaluated, only those tests for which a cut-off was provided were included.Description of small bowel biopsy procedure clearly outlined (location, number of biopsies per patient), unless if specified that celiac disease diagnosis guidelines were followed.Patients in the treatment group had untreated CD.Studies on screening of the general asymptomatic population.Studies that evaluated rapid diagnostic kits for use either at home or in physician's offices.Studies that evaluated diagnostic modalities other than serologic tests such as capsule endoscopy, push enteroscopy, or genetic testing.Cut-off for serologic tests defined based on controls included in the study.Study population defined based on positive serology or subjects pre-screened by serology tests.Celiac disease status known before study enrolment.Sensitivity or specificity estimates based on repeated testing for the same subject.Non-peer-reviewed literature such as editorials and letters to the editor.

POPULATION

The population consisted of adults and children with untreated, undiagnosed celiac disease with symptoms consistent with the disease.

SEROLOGIC CELIAC DISEASE TESTS EVALUATED

Anti-gliadin antibody (AGA)Anti-endomysial antibody (EMA)Anti-tissue transglutaminase antibody (tTG)Anti-deamidated gliadin peptides antibody (DGP)Combinations of some of the serologic tests listed above were evaluated in some studiesBoth IgA and IgG antibodies were evaluated for the serologic tests listed above.

OUTCOMES OF INTEREST

SensitivitySpecificityPositive and negative likelihood ratiosDiagnostic odds ratio (OR)Area under the sROC curve (AUC)Small bowel biopsy was used as the gold standard in order to estimate the sensitivity and specificity of each serologic test.

STATISTICAL ANALYSIS

Pooled estimates of sensitivity, specificity and diagnostic odds ratios (DORs) for the different serologic tests were calculated using a bivariate, binomial generalized linear mixed model. Statistical significance for differences in sensitivity and specificity between serologic tests was defined by P values less than 0.05, where "false discovery rate" adjustments were made for multiple hypothesis testing. The bivariate regression analyses were performed using SAS version 9.2 (SAS Institute Inc.; Cary, NC, USA). Using the bivariate model parameters, summary receiver operating characteristic (sROC) curves were produced using Review Manager 5.0.22 (The Nordiac Cochrane Centre, The Cochrane Collaboration, 2008). The area under the sROC curve (AUC) was estimated by bivariate mixed-efects binary regression modeling framework. Model specification, estimation and prediction are carried out with xtmelogit in Stata release 10 (Statacorp, 2007). Statistical tests for the differences in AUC estimates could not be carried out. The study results were stratified according to patient or disease characteristics such as age, severity of Marsh grade abnormalities, among others, if reported in the studies. The literature indicates that the diagnostic accuracy of serologic tests for celiac disease may be affected in patients with chronic liver disease, therefore, the studies identified through the systematic literature review that evaluated the diagnostic accuracy of serologic tests for celiac disease in patients with chronic liver disease were summarized. The effect of the GFD in patiens diagnosed with celiac disease was also summarized if reported in the studies eligible for the analysis.

SUMMARY OF FINDINGS

PUBLISHED SYSTEMATIC REVIEWS: Five systematic reviews of studies that evaluated the diagnostic accuracy of serologic celiac disease tests were identified through our literature search. Seventeen individual studies identified in adults and children were eligible for this evaluation. (ABSTRACT TRUNCATED)

Diagnostic immunology in celiac disease

Serum autoantibodies to transglutaminase and endomysium are found in the majority of patients with celiac disease, an autoimmune multisystem disorder affecting approximately 1% of Western and Middle-Eastern populations. Detection of these antibodies plays a crucial role in the diagnosis of celiac disease. The aim of this review is to summarize recent publications in this field, with particular focus on the applications and limitations of celiac autoantibody testing in routine clinical practice.

Use of likelihood ratios improves clinical interpretation of IgA anti-tTG antibody testing for celiac disease

BACKGROUND

We investigated whether taking into account IgA anti-tissue transglutaminase antibody concentration (IgA anti-tTG) and total IgA concentration could improve clinical interpretation of serologic testing for celiac disease (CD).

METHODS

We retrospectively identified 43 consecutive newly diagnosed CD patients and 545 consecutive disease control patients who had an IgA anti-tTG request during the 42-month study period and for whom intestinal biopsy results were available.

RESULTS

Sensitivity and specificity of the IgA anti-tTG assay from Genesis was 95.3% and 92.7%, respectively, with a likelihood ratio (LR) of 12.4. The LR for CD markedly increased with increasing IgA anti-tTG concentration (from 2.0 for results between 7 and 20 U/ml up to 319 for results >100 U/ml). The LR for CD was also higher in patients with a normal IgA concentration (0.82-4.53 g/L) compared to patients with an increased IgA concentration (15.3 vs. 3.1, respectively). These observations were confirmed with a second IgA anti-tTG assay from BioRad.

CONCLUSION

Sensitivity of IgA anti-tTG was good. Specificity, however, was reduced when IgA anti-tTG was weak positive or when the IgA concentration was increased. Taking into account IgA anti-tTG concentration and IgA concentration improves clinical interpretation of serologic testing for CD.

Liver involvement in celiac disease

Celiac disease is a chronic immune-mediated disorder that may affect several organs. Liver abnormalities are common extraintestinal manifestations of celiac disease. Isolated hypertransaminasemia, with mild or nonspecific histologic changes in the liver biopsy, also known as ''celiac hepatitis'', is the most frequent presentation of liver injury in celiac disease. Both, histologic changes and liver enzymes reverse to normal after treatment with a gluten-free diet in most patients. Celiac disease may also be associated with severe forms of liver disease and/or coexist with other chronic liver disorders (i.e., autoimmune liver diseases). The mechanisms underlying liver injury in celiac disease are poorly understood. Predisposition to autoimmunity by shared genetic factors (i.e., human leukocyte antigen [HLA] genes) as well as the systemic effects of abnormal intestinal permeability, cytokines, autoantibodies, and/or other yet undefined biologic mediators induced by gluten exposure in susceptible persons may play a pathogenic role. The aims of this article are: 1) to review the spectrum of liver injury related to celiac disease and 2) to understand the clinical implications of celiac disease in patients with chronic liver disorders.

Autoantibodies in celiac disease

Autoantibody production is an important feature of many autoimmune disorders, signifying a breakdown of immune tolerance to self-antigens. In celiac disease, an autoimmune enteropathy with multiple extra-intestinal manifestations, autoantibody reactivity to transglutaminase 2 (TG2) has been shown to closely correlate with the acute phase of the disease. It serves as a specific and sensitive marker of celiac disease, and is highly useful in aiding diagnosis and follow-up. Immune reactivity to other autoantigens, including transglutaminase 3, actin, ganglioside, collagen, calreticulin and zonulin, among others, has also been reported in celiac disease. The clinical significance of these antibodies is not known, although some may be associated with specific clinical presentations or extra-intestinal manifestations of celiac disease. This review examines the presence of anti-TG2 and other autoantibodies in celiac disease, discussing their diagnostic value, their potential role in disease pathogenesis and current hypotheses that explain how their release may be triggered.

Chronic hepatitis C virus and celiac disease, is there an association?

Celiac disease (CD) has been epidemiologically associated with chronic hepatitis C (HCV), and CD activation after the initiation of interferon (IFN-alpha) in patients with HCV is documented. However, clear association of CD and HCV is lacking. A prospectively maintained database of 878 CD patients showed a prevalence of 0.68% (six patients). Symptoms of diarrhea, weight loss, and depression prompted the diagnosis of CD during or after IFN-alpha therapy in four cases. Also, 294 subjects with liver disease (195 with HCV, 80 normal controls and 19 disease controls) were prospectively screened for CD. The mean age of the subjects was 50.1 years (SD 12.3), 58% males:42% females. A total of 30% received IFN-alpha therapy (16% at the time of testing for CD). Two HCV patients (1%) had positive tTG-IgA but these had negative endomysial antibody (EMA) and normal duodenal biopsies. CD prevalence is not increased in patients with HCV. Routine screening of CD in HCV patients is not warranted, however, the presence of CD should be considered in the setting of clinical deterioration during or after IFN-alpha therapy.

The liver in celiac disease

Celiac disease is a common (1% prevalence) chronic immune-mediated disorder of the small intestine induced by dietary wheat, barley, and rye. Several hepatic disorders have been described in association with celiac disease. Isolated hypertransaminasemia with nonspecific histologic changes in a liver biopsy is the commonest hepatic presentation of celiac disease. A gluten-free diet normalizes liver enzymes and histologic changes in most patients. Moreover, celiac disease can coexist with autoimmune liver disorders such as autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis. Celiac disease has increasingly been reported with a variety of other liver diseases. Thus, the hepatologist needs to consider celiac disease in the differential of abnormal liver blood tests and to be aware of the clinical implications of this frequent disease in patients with liver disorders. The possible mechanisms of liver injury and those common factors that explain the association of celiac disease with liver disorders are discussed. The aims of this article are (1) to review the spectrum and pathogenesis of liver injury related to celiac disease and (2) to provide direction to those caring for patients with chronic liver diseases regarding the detection and effective treatment of celiac disease.

Increasing prevalence of coeliac disease over time

BACKGROUND

The number of coeliac disease diagnoses has increased in the recent past and according to screening studies, the total prevalence of the disorder is around 1%.

AIM

To establish whether the increased number of coeliac disease cases reflects a true rise in disease frequency.

METHODS

The total prevalence of coeliac disease was determined in two population-based samples representing the Finnish adult population in 1978-80 and 2000-01 and comprising 8000 and 8028 individuals, respectively. Both clinically-diagnosed coeliac disease patients and previously unrecognized cases identified by serum endomysial antibodies were taken into account.

RESULTS

Only two (clinical prevalence of 0.03%) patients had been diagnosed on clinical grounds in 1978-80, in contrast to 32 (0.52%) in 2000-01. The prevalence of earlier unrecognized cases increased statistically significantly from 1.03% to 1.47% during the same period. This yields a total prevalence of coeliac disease of 1.05% in 1978-80 and 1.99% in 2000-01.

CONCLUSIONS

The total prevalence of coeliac disease seems to have doubled in Finland during the last two decades, and the increase cannot be attributed to the better detection rate. The environmental factors responsible for the increasing prevalence of the disorder are issues for further studies.

Tissue transglutaminase ELISA positivity in autoimmune disease independent of gluten-sensitive disease

BACKGROUND

Our aim was to understand why some sera from patients with a broad spectrum of autoimmune diseases or non-autoimmune diseases involving enhanced apoptosis, cell lysis and/or putative secondary autoimmune processes show reactions in the tissue transglutaminase (TGc) ELISA used for diagnosis of gluten-sensitive disease.

METHODS

Sera were compared from groups of patients with autoimmune diseases, diseases involving organ specific enhanced cell death, celiac disease or dermatitis herpetiformis, diseases of non-autoimmune origin, and a group without known disease. IgA antibodies against TGc were detected using human antigen (produced recombinantly in bacterial or human cells) in different systems (non-commercial ELISA with buffers of differing NaCl concentrations, and anti-TGc sandwich ELISA). Anti-gliadin and anti-endomysium antibodies were also determined.

RESULTS

Many sera from patients with autoimmune disorders gave a positive signal in the human TGc ELISAs. The signal appeared related to minor impurities in the recombinant human TGc used and to raised serum IgA antibody levels rather than to the occurrence of TGc specific antibodies in these patients.

CONCLUSIONS

No association of anti-TGc Abs and autoimmune conditions independent of gluten-sensitive disease could be shown. Care should be taken to exclude copurification of chaperones, like heat shock protein 70, where preparing antigens for TGc ELISAs.

Gluten intolerance: sex and age-related features

OBJECTIVE

Gluten intolerance is an immune-mediated enteropathy associated with gluten-containing foods in genetically susceptible patients. The typical form mainly affecting children shows failure to thrive and/or gastrointestinal symptoms. The adult form is less typical, presenting vague gastrointestinal symptoms, iron deficiency (with or without anemia) or nonspecific serum chemistry abnormalities. The present study aims to analyze clinical and biochemical differences of celiac disease (CD) according to sex and age.

PATIENTS AND METHODS

The present study reviewed clinical and biochemical features of patients with suspected CD admitted to the Hospital General of Móstoles (Madrid, Spain) between July 2001 and June 2005. Two hundred fifty-two patients were analyzed, in whom intestinal biopsy was performed due to clinical and/or biochemical abnormalities suggestive of CD. One hundred seventy-eight asymptomatic relatives of the affected patients were also included. Overall, 125 patients showed diagnostic features of CD in the intestinal biopsy.

RESULTS

The results confirmed higher prevalence of typical forms of CD in children (67% in children compared with only 14.3% in adults). CD seemed to be more frequent in adult women than in men (ratio of women to men 4:1), but it is worth noting that men diagnosed were most often referred with a typical clinical picture, so atypical forms of the disease in men may have been underdiagnosed.

CONCLUSIONS

CD shows atypical features in adults, and physicians must include this disorder in the differential diagnosis of adults with iron deficiency or slight hypertransaminasemia. Increased awareness of the disease and extensive availability of accurate sero-logical tests will lead to improved diagnosis of this disorder, both in children and adults.

Diagnosis of celiac disease

Celiac disease is an immune mediated enteropathy initiated by ingestion of gluten, in genetically susceptible individuals. With changing epidemiology, celiac disease initially thought to affect only Europeans, has been increasingly reported from other parts of the world including India. However, its true prevalence in India is still not known, as the diagnosis is being missed. The gold standards for diagnosis have been characteristic small intestinal mucosal changes on gluten and a full clinical remission on its removal from the diet. Presence of serological antibodies, which disappear on gluten free diet further confirms the diagnosis. The understanding of the histopathology of celiac disease has changed over the years. The small bowel mucosal lesion of celiac disease is an evolutionary process with normal mucosal architecture and an increase in intraepithelial lymphocytes at one end of the spectrum and classical flat mucosa at the other. In the Indian subcontinent celiac disease has a heterogeneous histological presentation and the diagnosis may be missed if it is based only on severe mucosal changes or the serology is not considered when moderate or mild mucosal changes are present. The last two decades have shown that antiendomysical (Anti EMA) and anti tissue transglutaminase antibodies (anti-tTGA) have a sensitivity and specificity of more than 95% to diagnose celiac disease. Anti EMA tests being operator dependent are more liable to errors and anti- tTGA may be preferred for large scale screening. However, the different source of tTGA antigen, varied techniques of production and the use of arbitrary units by different commercial kits can influence the diagnostic accuracy of the anti-tTGA assay. There is a strong genetic association of celiac disease with HLA-DQ2 or DQ8. The presence of HLA-DQ2 hetrodimer in more than 97% of a group of North Indian patients with celiac disease indicates that this population has a similar genetic risk for the disease. HLA DQ2 typing can be used for ruling out celiac disease where the diagnosis is equivocal as it has a negative predictive value of greater than 95%. Given the protean clinical manifestation and the heterogeneous histology a standard algorithm for diagnosis of celiac disease is important.

Low specificity of anti-tissue transglutaminase antibodies in patients with primary biliary cirrhosis

The association between celiac disease (CD) and primary biliary cirrhosis (PBC) is well documented in medical literature; however, a high frequency of false positive results of the anti-transglutaminase (anti-tTG) test has been reported in patients with PBC. To verify if the positive results for anti-tTG autoantibody are false positives due to cross reactivity with mitochondrial antigens, we studied 105 adult patients affected with PBC, positive for anti-mitochondrial M2 antibodies. Anti-tTG IgA antibodies were studied by using six different immunoenzymatic assays that employ the tTG antigen obtained from different sources (human recombinant, placenta, red blood cells, and guinea pig liver). On the whole, 28 out of 105 PBC subjects tested positive for anti-tTG IgA antibodies, but only two were eventually found to be affected by CD; the other 26 were shown to be false positive. The specificity of the various antigenic substrates ranged from 88.5% of the human erythrocytes tTG to 97.1% of the human recombinant tTG. The results of this study showed that a true association between PBC and CD was present in only 2% of the patients and that, in most cases, the false positive results were attributable to the type of substrate utilized in the assay.

Prevalence and clinical significance of immunoglobulin A antibodies against tissue transglutaminase in patients with diverse chronic liver diseases

The prevalence of celiac disease (CD) and the prevalence and clinical significance of anti-tissue transglutaminase (tTG) antibodies (tTGAbs) in a large series of patients with chronic liver diseases were assessed. We studied 738 patients (462 with chronic viral hepatitis, 117 with autoimmune liver diseases, 113 with alcoholic or nonalcoholic fatty liver disease, and 46 with other liver disorders) and 1,350 healthy controls (HC). Immunoglobulin A (IgA) tTGAbs were measured by enzyme-linked immunosorbent assay and a microsphere-based flow cytometric assay. Positive sera were investigated for IgA antiendomysial antibodies (EmA). IgA tTGAb-positive subjects were invited to undergo a small-intestinal biopsy and HLA-DQ allele typing. Four of 1,350 HC (0.3%) tested tTGAb(+) EmA(+) and underwent a biopsy (CD confirmation in all). Four of 738 liver disease patients tested tTGAbs(+) EmA(+) (0.54%; not statistically significant). Two were HCV infected (1.24%; not statistically significant), and two had transaminasemia of unknown origin. Forty-three patients tested tTGAbs(+) EmA(-) (5.8%; P<0.001 compared to HC). Inhibition experiments verified the existence of specific IgA anti-tTG reactivity. Twenty-six of 43 patients underwent a biopsy (all negative for CD). Binary logistic regression analysis revealed age (P=0.008), cirrhosis (P=0.004), alkaline phosphatase (P=0.026), and antinuclear antibodies (P=0.012) as independent risk factors for tTGAb reactivity among the patients. It was concluded that CD prevalence is the same in HC and patients with chronic liver diseases. The prevalence of tTGAbs is higher in hepatic patients compared to HC, but their specificity for CD diagnosis in this group of patients is low. tTGAbs in patients appear to be associated with the presence of autoimmunity, cirrhosis, and cholestasis, irrespective of the origin of the liver disease.

Increasing numbers at a specialist coeliac clinic: contribution of serological testing in primary care

BACKGROUND

Serological testing, using IgA class endomysial and tissue transglutaminase antibodies has high sensitivity and specificity for coeliac disease and allows case finding by clinicians other than gastroenterologists. We reviewed new coeliac patients seen over a 9-year period to determine how the availability of serology, particularly to primary care physicians, has changed rates and sources of diagnosis.

METHODS

Files of patients attending a specialist coeliac clinic who were diagnosed from 1996 through 2004 were reviewed. Patients with villous atrophy consistent with gluten sensitive enteropathy (Marsh III) on duodenal biopsy were selected. Data analysed included clinical characteristics, endomysial and tissue transglutaminase antibodies status and source of request for serology.

RESULTS

Over the study period 347 new coeliac patients, comprising adults and children aged 10 years and over, were identified, of whom 163 (47%) were identified by serological testing in primary care, 152 (44%) at the hospital gastroenterology department and 32 (9%) by other physicians in secondary care. Over three consecutive 3-year periods, the percentage of patients identified in primary care rose from 28% through 47% to 60%, with a rise in total numbers diagnosed from 93 through 118 to 136. There was no change in patient clinical characteristics over the study period. Though tissue transglutaminase antibodies were less sensitive than endomysial antibodies, combined testing obtained a sensitivity of over 90%. Patients identified in primary care were significantly younger and more likely to present with diarrhoea as a primary symptom.

CONCLUSION

Currently over half of our coeliac patients are identified by serological testing in primary care, which has resulted in an overall rise in diagnosis rates. Primary care practitioners have an important role in the diagnosis of coeliac disease, particularly of patients who present with non-gastrointestinal symptoms. The contribution of specialists other than gastroenterologists in secondary care is disappointing and may improve with directed education.

Anti-tissue transglutaminase antibodies in patients with abnormal liver tests: is it always coeliac disease?

BACKGROUND

Coeliac disease (CD) is found in 5-10% of patients with chronically abnormal liver tests and no obvious cause of liver disease. In this population the efficacy of screening for CD by anti-tissue transglutaminase (anti-tTG) may be impaired by the high rate of positive anti-tTG found in chronic liver disease.

AIMS

To evaluate the prevalence of coeliac disease and the role of anti-tTG in patients with non-viral, non-autoimmune chronic and no obvious cause of liver damage.

METHODS

Out of 2,512 consecutive patients with abnormal liver tests, 168 (118 men, 50 women; mean age 40.7 +/- 12.6 years) were defined, on the basis of clinical data and liver biopsy, as NAFLD or cryptogenic chronic hepatitis. All were tested by recombinant IgA and IgG anti-tissue transglutaminase. Patients with a positive serology underwent endoscopy with duodenal biopsies.

RESULTS

NAFLD was diagnosed in 121 patients, in 6 associated with cirrhosis, while 47 patients were considered as cryptogenic hepatitis in the absence of steatosis. Anti-tTG were positive in 20/168 patients (3 IgA alone; 11 IgG alone; 6 both IgA and IgG). Coeliac disease was found at endoscopy and confirmed by histopathology only in the 6 patients (3.6%) with both IgA and IgG anti-tTG positivity. Four of the patients with CD had NAFLD (3.3%), in 2 of them associated with cirrhosis; while 2 of those with cryptogenic hepatitis (4.2%) had CD.

CONCLUSIONS

The prevalence of CD in patients with chronically abnormal liver tests of unexplained etiology is 4%, with no relation with the degree of liver steatosis. Screening should be done by testing for IgA and IgG antibodies and then evaluating by endoscopy and biopsy only patients positive for both.

Evaluation of a microsphere-based flow cytometric assay for diagnosis of celiac disease

The multiplexed particle-based flow cytometric technology proposes a new approach for the diagnosis of autoimmune diseases combining the advantages of conventional methods with the ability to quantitatively determine multiple autoantibodies in the same sample, simultaneously and rapidly. Recently, a commercial kit (FIDIS Celiac, Biomedical Diagnostics, Mane la Vallé, France) was introduced for the simultaneous detection of IgA anti-tissue transglutaminase (anti-tTG), IgG, and IgA anti-gliadin antibodies (AGA). This study was undertaken to evaluate and compare the FIDIS Celiac kit with standardized commercial ELISAs (QUANTA Lite, INOVA Diagnostics Inc., San Diego, CA). A disease group consisted of 21 samples from untreated patients with biopsy confirmed celiac disease (CD), and two control groups of historical sera (207 from regular blood donors and 181 from chronically infected hepatitis patients) were studied. All control sera were negative for IgA anti-endomysial antibodies (EmA) and had an IgA concentration above the lower normal limit. Concerning the reproducibility, intra- and inter-assay coefficients of variation (CVs) ranging between 2% and 12%, and between 3% and 21%, respectively, were observed. Regarding the diagnostic quality, each assay was compared to the disease diagnosis using the McNemar test and the kappa (K) parameter, while ROC analysis was applied. Generally, the performance of FIDIS assay was proved almost equally adequate to that of ELISA in the detection of IgA anti-tTG antibodies, IgA and IgG AGA. However, the performance of FIDIS assay was found surmounting that of ELISA among hepatitis patients, possibly due to the avoidance of debris and unbound cross contaminants and, hence, the "noise" of such materials in samples under analysis. Taking our results together with the simplicity and the high throughput of FIDIS assay, its overall performance in the diagnosis of CD seems better than that of ELISA.

False positive reactions for IgA and IgG anti-tissue transglutaminase antibodies in liver cirrhosis are common and method-dependent

BACKGROUND

Conflicting results were obtained in the assay of anti-transglutaminase (anti-tTG) autoantibodies in patients with chronic liver disease. In order to establish whether this was attributable to methodological differences, anti-tTG antibodies were assayed in a large number of patients suffering from liver cirrhosis (LC).

METHODS

54 patients with LC and 29 patients suffering from celiac disease (CD), used as controls, were tested for IgA and IgG anti-tTG with 11 different commercial methods.

RESULTS

In the patients with LC, positivity ranged from 0% to 33.3% for IgA anti-tTG and from 0% to 11.1% for anti-tTG of the IgG class. The largest number of false positives was found with methods that used tTG in association with gliadin peptides as antigen substrate. A significant association was found between IgA anti-tTG antibodies and serum immunoglobulin concentration.

CONCLUSIONS

The results of the various methods of assaying anti-tTG antibodies in patients with LC are highly variable, and the positives found are generally false positives, partly due to the high immunoglobulin concentration.

High prevalence of celiac disease in autoimmune hepatitis detected by anti-tissue tranglutaminase autoantibodies

Celiac disease (CD) may be found in association with other autoimmune diseases. We investigated the relation between autoimmune hepatitis (AIH) and CD by assessing the prevalence of IgA and IgG anti-tissue transglutaminase (tTG) antibodies in AIH, and by verifying whether the findings were associated with clinical and histological features of CD. Forty-seven consecutive patients with AIH (type I: n = 39; type II: n = 8) were studied. One hundred patients with chronic hepatitis C, and 120 healthy blood donors were also studied as controls. We analyzed sera for the presence of IgA and IgG anti-tTG antibodies using a specific human recombinant tTG immunoenzymatic assay. Anti-tTG positive patients and controls were further tested for anti-endomysium antibodies (EMA) and HLA typing, and those found positive by either of these tests underwent duodenal biopsy to confirm a possible diagnosis of CD. Three of the 47 AIH patients (6.4%) were positive for IgA anti-tTG and EMA antibodies, and were subsequently confirmed to be affected with CD by small-bowel biopsy findings. No IgG anti-tTG positivity was found in the AIH patients. None of the controls were positive for IgA anti-tTG, and only one with chronic hepatitis C had a low positive reaction for IgG anti-tTG, which resulted as a false positive. The crude prevalence rate of CD in AIH was 63.8 per 1,000 (95% CI, 13.2-186.1), and it was significantly higher than that found in the general population in Italy (4.9 per 1,000; 95% CI, 2.8-7.8). The results of this study showed a high prevalence of CD in patients with AIH. For this reason, early serological screening testing for CD is strongly recommended for all AIH patients.

Celiac disease in the Turkish population

Celiac disease (CD) is characterized by malabsorption of nutrients in the small intestine. The availability of highly specific and sensitive serologic tests has facilitated its diagnosis, increasing the disease prevalence. The aim of this study was to determine the clinical, laboratory, and histopathological features of CD in Turkish adults. Between 1968 and 2002, CD patients presenting to the Gastroenterology Unit were evaluated retrospectively. From 2002, newly diagnosed patients were prospectively followed up. Sixty patients (39 female, 21 male) were included in the study. Mean body mass index was 22.2 +/- 5.4 kg/m2. The most common symptoms were diarrhea, weight loss, and flatulence. Most common comorbidities were anemia, osteoporosis, type 1 diabetes mellitus, and steatohepatitis. Six (10.0%) patients had a family history of diabetes mellitus; one (1.7%) patient had a family history of CD. Plasma glucose and serum gamma-glutamyltransferase levels were significantly higher in females than males. Most common histopathological findings were increased lymphocytes in the lamina propria (76.2%) and villus epithelium (59.5%). Over the years, the cumulative frequency of CD increased more in females than males. This is the first study in the literature showing the characteristics of CD in Turkish adults. In our previous recent study, the prevalence of tissue transglutaminase antibody positivity in Turkish healthy blood donors was 1.3%, indicating a high prevalence of CD in our population. In this study, the cumulative frequency of CD increased more in females than males. With the better understanding and increased suspicion of the disease, more patients are being diagnosed in our population.

Tissue transglutaminase--the key player in celiac disease: a review

Gluten-sensitive enteropathy, otherwise known as celiac sprue, is characterized by an abnormal proximal small intestinal mucosa arising as a result of an inappropriate inflammatory response to ingested gluten antigens present in wheat in genetically susceptible individuals. This immune response is directed to a 33-mer peptide of the alpha gliadin component of gluten. The generation of an epitope for the recognition by CD4+ T cells requires deamination of the protein by tissue transglutaminase (tTG). Moreover, IgA anti tTG is highly sensitive and is specific serologic marker (95-99%) of celiac disease. They can be easily determined quantitatively, by ELISA of an accurate and relatively inexpensive technique. Therefore, tTG can be used as the first line diagnostic test in the work-up of celiac disease, as well as for screening purposes. Finally, tTG may contribute to future strategies in treating celiac disease either by producing nontoxic wheat or by generating oral vaccination that can prevent the disease.

Epitopes recognised by tissue transglutaminase antibodies in coeliac disease

The interaction between IgA tissue transglutaminase (tTG) antibodies (Abs) and 35S-labelled tTG produced in a transcription/translation (TnT) system with various amino acid (aa) deletions has been studied. These experiments showed that the tTG N-terminal aa 1-89 were important for tTG Ab binding in all 15 coeliac disease sera studied and the central residues (aa 401-491) were important for binding of tTG Abs in all but one sera. The contribution of C-terminal residues to tTG Ab binding varied in different coeliac sera but overall was less than the contributions of the N terminal and central regions. Mouse monoclonal antibodies (MAbs) to tTG were produced and the tTG aa sequences recognised by the MAbs determined using modified 35S-labelled tTG proteins. Analysis of the inhibiting effects of patient sera tTG Ab on binding of tTG MAbs to tTG confirmed the importance of the N-terminal and central regions of tTG in forming serum tTG Ab binding sites. Recombinant human tTG was expressed in yeast and purified to better than 95% homogeneity using MAb affinity chromatography as a final purification step. This material was highly suitable for use in an ELISA for tTGAb.

Diagnostic Accuracy of Ten Second-Generation (Human) Tissue Transglutaminase Antibody Assays in Celiac Disease

Background: Anti-tissue transglutaminase (tTG) assays that use human tTG as antigen have recently become available. We evaluated commercially available assays with human tTG antigen to estimate their diagnostic accuracies and to determine whether they agree sufficiently to be used interchangeably.

Methods: Ten commercially available second-generation anti-tTG assays were evaluated. The following populations were studied: celiac disease (CD) patients at the time of diagnosis without (n = 70) or with (n = 5) IgA deficiency; diseased controls (n = 70); and CD patients without (n = 28) or with (n = 2) IgA deficiency during follow-up. All individuals included in the study underwent intestinal biopsy. Technical performance (linearity, interference, precision, correlation, and agreement) and diagnostic accuracy (sensitivity and specificity) were compared. Anti-gliadin and anti-endomysium antibodies were also measured.

Results: IgA anti-tTG results correlated well overall, but numerical values differed. Diagnostic sensitivity ranged between 91% and 97% and specificity between 96% and 100%. These were higher than the sensitivity and specificity of the IgA endomysium assay and the IgA gliadin assay. Generally, IgG anti-tTG was less sensitive but more specific than IgG anti-gliadin for the diagnosis of CD in the small group of IgA-deficient patients.

Conclusions: Overall diagnostic performance of IgA tTG assays is acceptable and comparable among the different assays, but numerical values differ. Standardization is needed.

Epitopes of calreticulin recognised by IgA autoantibodies from patients with hepatic and coeliac disease

Calreticulin (CRT) was identified as a frequent target of serum autoantibodies (Ab) in various diseases, but anti-CRT Ab of IgA isotype were described only in coeliac (CLD) and some hepatic diseases. Employing ELISA with recombinant CRT we found significantly higher (P<0.001) levels of IgA anti-CRT Ab in sera of patients with primary biliary cirrhosis (PBC) (77.6+/-8.9 AU/mean+/-SE), autoimmune hepatitis (AIH) (105.1+/-9.2 AU) and alcoholic liver cirrhosis (ALC) (193.5+/-21.0 AU) relative to healthy controls (38.6+/-2.0 AU). The levels of IgG anti-CRT Ab in sera of patients with PBC (59.5+/-3.4 AU), AIH (89.7+/-7.9 AU) and ALC (86.4+/-6.2 AU) were also significantly increased (P<0.001) when compared with controls (38.5+/-2.1 AU). Pepscan technique with decapeptides of CRT (each overlapping by eight amino acids) revealed antigenic epitopes of this molecule recognised by IgA Ab of almost all tested patients-KGKNVLINKD and QVKSGTIFDNFL. We also identified disease specific antigenic epitopes on CRT molecule, predominantly recognised by IgA Ab of patients suffering from a particular disease: GGYVKLFPNS and YVKLFPNSLD in AIH (83%, 92% of patients), GLQTSQDARF and EQRLKEEEED in CLD (both 75%) and ASKPEDWDER in ALC (67%). Identification of disease specific CRT epitopes contributes to clarification of autoreactivity against this molecule.

Searching for coeliac disease in patients with non-alcoholic fatty liver disease

BACKGROUND

A non-negligible percentage of patients with non-alcoholic fatty liver disease, a leading cause of hepatic progressive disorder related to insulin resistance, have no metabolic risk factors, and abnormal intestinal permeability has been suggested to be involved in the pathogenesis of the liver damage. Coeliac disease, a curable disorder characterised by inflammatory mucosal damage, may show hepatic histological features similar to steatohepatitis. Conflicting data have been reported on the prevalence of coeliac disease in non-alcoholic steatohepatitis.

AIM

To search for coeliac disease in a series of patients with non-alcoholic fatty liver disease by screening with anti-tissue transglutaminase and anti-endomysium antibodies.

PATIENTS AND METHODS

Fifty-nine consecutive patients with hypertransaminasemia and non-alcoholic fatty liver disease, 38 (64%) with steatohepatitis. Anti-endomysium antibodies were assayed by indirect immunofluorescence, IgA anti-tissue transglutaminase by ELISA. Patients who tested positive underwent HLA DQ typing and endoscopy.

RESULTS

Tissue transglutaminase antibodies were positive in six (10%) patients and anti-endomysium in two (3.4%); only two (3.4%), positive for both anti-endomysium positive and anti-transglutaminase, resulted to have coeliac disease based on histological findings. After 6 months of gluten-free diet, liver enzymes normalised.

CONCLUSIONS

The prevalence of silent coeliac disease is 3.4% in patients with non-alcoholic fatty liver. The inclusion of anti-endomysium antibodies test in studying patients with non-alcoholic fatty liver and persistent biochemical abnormalities has to be taken into account, since positivity for tissue transglutaminase antibodies, in the absence of confirmatory anti-endomysium antibodies, is not sufficient to perform diagnostic endoscopy.

Association of celiac disease with connective tissue diseases and autoimmune diseases of the digestive tract

Celiac disease (CD) is an autoimmune enteropathy triggered by the ingestion of gluten in susceptible individuals, and is one of the most frequent genetically based diseases, with a prevalence of 1:200 in the general population. The association between CD and connective tissue diseases (CTD) and autoimmune diseases of the digestive tract (DT) has been described in several case reports but in few extensive studies, with varying prevalence. A high rate of false positive results were observed when low specific tests, such as the anti-gliadin and the guinea pig tissue transglutaminase (tTG) antibody assays were used. In a study of 400 patients with CTD and 218 with autoimmune DT disease, tested for IgA and IgG anti-tTG using the more specific human recombinant antigen, 12 cases (1.9%) of anti-tTG antibody positivity were found, but only 2 (0.3%) were confirmed as affected by CD following small bowel biopsy. Most of the patients testing false positive had primary biliary cirrhosis. In this short review we describe the association between CD and CTD, inflammatory bowel disease and primary biliary cirrhosis, with special emphasis on the diagnostic accuracy of CD antibody assays.

Anti-tissue transglutaminase antibodies in inflammatory bowel disease: new evidence

Anti-tissue transglutaminase, previously held to be identical to anti-endomysial antibodies in celiac sprue, has been reported in inflammatory bowel disease patients. To investigate these data further, we evaluated serum and intestinal anti-tissue transglutaminase in inflammatory bowel disease patients, with respect to the Crohn’s disease activity index and the integrated disease activity index. Study population comprised: 49 patients with Crohn’s disease and 29 patients with ulcerative colitis; 45 patients with celiac sprue and 85 autoimmune patients as disease controls; and 58 volunteers as healthy controls. Immunoglobulin A (IgA) anti-recombinant human tissue transglutaminase and anti-endomysial antibody detection in sera and fecal supernatants were performed. Adsorption of positive sera with recombinant human tissue transglutaminase were also performed. Marked increased anti-tissue transglutaminase concentrations were found in celiac sprue, while low-positive values were also found in Crohn’s disease and ulcerative colitis. Anti-endomysial antibodies were detectable only in celiac sprue. Antigen adsorption resulted in a significant reduction of the anti-tissue transglutaminase either in celiac sprue or inflammatory bowel disease sera. A significant correlation between anti-tissue transglutaminase and Crohn’s disease activity index or integrated disease activity index scores was found. Anti-tissue transglutaminase was also detectable in fecal supernatants from inflammatory bowel disease patients. Data highlight that both circulating and intestinal anti-tissue transglutaminases are detectable in inflammatory bowel disease, and that they are related to disease activity. These features underline that, in addition to anti-tissue transglutaminase, an anti-endomysial antibody test is necessary in the diagnostic work-up of celiac sprue, especially in patients with known inflammatory bowel disease.

IgA and IgG tissue transglutaminase antibody prevalence and clinical significance in connective tissue diseases, inflammatory bowel disease, and primary biliary cirrhosis

An association between celiac disease (CD) and other autoimmune diseases such as connective tissue diseases (CTD), inflammatory bowel diseases (IBD), and primary biliary cirrhosis (PBC) has been reported in several studies. However, a high rate of false positives in autoantibody testing was noted, especially when tissue transglutaminase (tTG) from guinea pig liver was used. Thus, the real prevalence of CD in CTD, IBD, and PBC is unclear. In a case-control study, 400 patients with CTD, 170 with IBD, 48 with PBC, and 120 healthy subjects were investigated for CD by the analysis of IgA and IgG tTG antibodies using the more specific human recombinant tTG immunoenzymatic assay. Patients and controls with positive findings were further tested for antiendomysial antibodies by indirect immunofluorescence and HLA typing, and those found positive by either of these tests underwent duodenal biopsy to confirm a possible diagnosis of CD. Twelve patients were positive for IgA or IgG tTG antibodies, showing an overall prevalence of 1.9%. Only 1 healthy subject (0.8%) had a low level positive reaction for IgA anti-tTG. Among the 12 patients and the healthy subject, only 2 (1 SLE and 1 ulcerative colitis patient) were subsequently confirmed to be affected with CD by positive EMA, HLA, and small bowel biopsy findings. The highest rate of false positives was found in PBC patients (10.4%). For these reasons, serological screening testing for CD is not recommended in CTD patients or in subjects affected with IBD or PBC, unless there is a relevant clinical suspicion of CD.

IgA and IgG tissue transglutaminase antibody prevalence and clinical significance in connective tissue diseases, inflammatory bowel disease, and primary biliary cirrhosis

An association between celiac disease (CD) and other autoimmune diseases such as connective tissue diseases (CTD), inflammatory bowel diseases (IBD), and primary biliary cirrhosis (PBC) has been reported in several studies. However, a high rate of false positives in autoantibody testing was noted, especially when tissue transglutaminase (tTG) from guinea pig liver was used. Thus, the real prevalence of CD in CTD, IBD, and PBC is unclear. In a case-control study, 400 patients with CTD, 170 with IBD, 48 with PBC, and 120 healthy subjects were investigated for CD by the analysis of IgA and IgG tTG antibodies using the more specific human recombinant tTG immunoenzymatic assay. Patients and controls with positive findings were further tested for antiendomysial antibodies by indirect immunofluorescence and HLA typing, and those found positive by either of these tests underwent duodenal biopsy to confirm a possible diagnosis of CD. Twelve patients were positive for IgA or IgG tTG antibodies, showing an overall prevalence of 1.9%. Only 1 healthy subject (0.8%) had a low level positive reaction for IgA anti-tTG. Among the 12 patients and the healthy subject, only 2 (1 SLE and 1 ulcerative colitis patient) were subsequently confirmed to be affected with CD by positive EMA, HLA, and small bowel biopsy findings. The highest rate of false positives was found in PBC patients (10.4%). For these reasons, serological screening testing for CD is not recommended in CTD patients or in subjects affected with IBD or PBC, unless there is a relevant clinical suspicion of CD.

Autoantibodies in the diagnosis and management of liver disease

Autoantibodies are nonpathogenic manifestations of immune reactivity, and they may occur in acute and chronic liver diseases. Autoantibodies may be consequences rather than causes of the liver injury, and they should be regarded as diagnostic clues rather than etiologic markers. Conventional autoantibodies used in the categorization of autoimmune liver disease are antinuclear antibodies, smooth muscle antibodies, antibodies to liver/kidney microsome type 1, antimitochondrial antibodies, and atypical perinuclear anti-neutrophil cytoplasmic antibodies. Ancillary autoantibodies that enhance diagnostic specificity, have prognostic connotation, or direct treatment are antibodies to endomysium, tissue transglutaminase, histones, doubled-stranded DNA, and actin. Autoantibodies that have an emerging diagnostic and prognostic significance are antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, liver cytosol type 1, and nuclear pore complex antigens. Autoantibodies of uncertain clinical value that remain under investigation are antibodies to chromatin, lactoferrin, and Saccharomyces cervisiae. Continued recognition and characterization of autoantibodies should improve diagnostic precision, provide prognostic indices, and elucidate target autoantigens. These advances may in turn clarify pathogenic mechanisms, facilitate the development of animal models, and generate novel site-specific therapies.

Coeliac disease

Coeliac disease is a genetically-determined chronic inflammatory intestinal disease induced by an environmental precipitant, gluten. Patients with the disease might have mainly non-gastrointestinal symptoms, and as a result patients present to various medical practitioners. Epidemiological studies have shown that coeliac disease is very common and affects about one in 250 people. The disease is associated with an increased rate of osteoporosis, infertility, autoimmune diseases, and malignant disease, especially lymphomas. The mechanism of the intestinal immune-mediated response is not completely clear, but involves an HLA-DQ2 or HLA-DQ8 restricted T-cell immune reaction in the lamina propria as well as an immune reaction in the intestinal epithelium. An important component of the disease is the intraepithelial lymphocyte that might become clonally expanded in refractory sprue and enteropathy-associated T-cell lymphoma. Study of the mechanism of the immune response in coeliac disease could provide insight into the mechanism of inflammatory and autoimmune responses and lead to innovations in treatment.

Screening for celiac disease in non-Hodgkin's lymphoma patients: a serum anti-transglutaminase-based approach

Several studies have shown the existence of an association between celiac disease (CD) and non-Hodgkin's lymphoma (NHL). Our aim was to evaluate the usefulness of the serum anti-tissue transglutaminase (anti-tTG) antibody assay in screening for CD in consecutive NHL patients. In all, 80 consecutive patients (median age 61 years) with a new diagnosis of NHL were included. To compare the frequency of CD and of positive results for the anti-tTG assay, we enrolled 500 blood donors. In all patients serum anti-tTG was determined with two different ELISA: one based on tTG from guinea pig (gp-tTG) and the other based on human recombinant t-TG (h-tTG) as the antigens. Serum anti-endomysial antibodies (EmA) were also assayed. Subjects with positive serum EmA and/or anti-tTG underwent intestinal biopsy for histology study, HLA-DQ phenotype determination, and serum anti-gliadin (AGA) assay. Eight of 80 (10%) NHL patients were positive for anti-tTG ELISA--two of these exclusively for anti-gp-tTG and six for anti-h-tTG (7.5%). None of the 80 NHL patients were positive for serum EmA. The frequency of anti-tTG positivity in the blood donor controls was 2/500 (0.4%), significantly lower than that observed in the NHL patients (P < 0.0001). Both these blood donors were found to have CD. Only in one anti-h-tTG-positive NHL patient was there intestinal mucosa atrophy, and follow-up confirmed a CD diagnosis (CD frequency in NHL patients is 1.2%; versus blood donors: P = 0.4). In all the other seven anti-tTG-positive NHL patients a normal intestinal architecture was found, although, inflammatory infiltration of the lamina propria was observed in four patients. No anti-tTG-positive NHL patients, including the subject diagnosed as having CD, had a family history of CD, and all had normal weight and no signs of malabsorption. Anti-tTG false positive results were associated with a higher frequency of serum autoantibody positivity and T-cell type NHL. In conclusion, NHL patients the anti-tTG assay often gives discordant data with the EmA assay, with a high frequency of anti-tTG false positive results for CD diagnosis.

Human recombinant anti-transglutaminase antibody testing is useful in the diagnosis of silent coeliac disease in a selected group of at-risk patients

BACKGROUND

Functional dyspepsia, unexplained chronic hypertransaminasaemia (CHT) and hepatitis C virus (HCV) are common gastrointestinal situations that have been related to coeliac disease. Antibodies to tissue transglutaminase (tTG) have been claimed recently to be highly effective as a screening method for coeliac disease.

AIM

To assess the prevalence of coeliac disease by means of detection of antibodies against human tTG in the above-mentioned groups of patients.

PATIENTS AND METHODS

A control group consisted of 165 normal blood donors. Patient groups comprised 90 CHT patients, 102 HCV patients and 92 functional dyspepsia patients. All patients were tested for anti-tTG (immunoglobulin A, IgA) antibodies. Anti-endomysium (IgA) antibodies (AEA) and antigliadin (IgA) antibodies (AGA) and antigliadin (immunoglobulin G, IgG) antibodies (AGG) were also tested. When anti-tTG or AEA was positive, a duodenal biopsy was recommended.

RESULTS

One of 165 blood donors, three of 92 functional dyspepsia patients, four of 90 CHT patients and none of 102 HCV patients were positive for anti-tTG antibodies. In the anti-tTG-positive group, all but one were AEA-positive. There were no AEA- or AGA IgA-positives that revealed a negative anti-tTG test. Duodenal biopsy confirmed a diagnosis of coeliac disease in all the cases. Statistically significant differences were found between the controls and the functional dyspepsia group and between the controls and the CHT group, but not between the controls and the HCV group.

CONCLUSIONS

Both CHT and functional dyspepsia may represent a true oligosymptomatic form of coeliac disease. In such conditions, the detection of anti-tTG antibodies is useful as a screening method. Coeliac disease is not an autoimmune manifestation of HCV, so screening for coeliac disease in HCV patients cannot be recommended.