Tissue transglutaminase antibodies in patients with end-stage heart failure

Are Tp-e interval and QT dispersion values important in children with coeliac disease?

OBJECTIVES

Coeliac disease is an autoimmune intestinal disease that develops with permanent intolerance to gluten and similar cereal proteins. It can damage to many tissues, including myocardium, by autoimmune mechanisms. In our study, we aimed to investigate the effect of coeliac disease on cardiac electrical activity by comparing the Tp-e interval and Qt dispersion values of coeliac patients with healthy children.

METHODS

Fifty-seven coeliac patients and 57 healthy children were included in the study. Sociodemographic findings, physical examinations, symptoms, laboratory values, dietary compliance, endoscopy, and pathological findings were recorded into a standardised form. Electrocardiogram parameters were calculated, and echocardiography findings were noted.

RESULTS

No statistically significant difference was found between the two groups in terms of age, gender, heart rate, electrocardiogram parameters such as p wave, PR interval, QRS complex, QT interval, and QTc values. Tp-e interval, Tp-e / QT ratio, and Tp-e / QTc ratio were statistically significantly higher in the patient group compared to the control group. Ejection fraction and fractional shortening values were significantly lower in the patient group compared to the control group. In the patient group, Tp-e interval, Tp-e / QT ratio, Tp-e / QTc ratio, and QTc dispersion were statistically significantly higher in patients with tissue transglutaminase IgA positive compared to patients with tissue transglutaminase IgA negative.

CONCLUSION

Our study gives important findings in terms of detecting early signs of future cardiovascular events in childhood age group coeliac patients.

Immuno-Sensing at Ultra-Low Concentration of TG2 Protein by Organic Electrochemical Transistors

Transglutaminase 2 (TG2) is a ubiquitously expressed member of the transglutaminase family with Ca2+-dependent protein crosslinking activity. Its subcellular localization is crucial in determining its function, and indeed, TG2 is found in the extracellular matrix, mitochondria, recycling endosomes, plasma membrane, cytosol, and nucleus because it is associated with cell growth, differentiation, and apoptosis. It is involved in several pathologies, such as celiac disease, cardiovascular, hepatic, renal, and fibrosis diseases, carrying out opposite functions of up and down regulation in the progression of the same pathology. Therefore, this fine regulation requires a very sensitive and specific method of identification of TG2, which is to be detected in very small quantities in a deregulated condition. Here, we demonstrate the possibility of detecting TG2 down to attomolar concentration by using organic electrochemical transistors driven by gold electrodes functionalized with anti-TG2 antibodies. In particular, a direct correlation between the TG2 concentration and the transistor transconductance values, as extracted from typical transfer curves, was found. Overall, our findings highlight the potentialities of this new biosensing approach for the detection of TG2 in the context of pathological diseases, offering a rapid and cost-effective alternative to traditional methods.

Implications of enigmatic transglutaminase 2 (TG2) in cardiac diseases and therapeutic developments

Cardiac diseases are the leading cause of mortality and morbidity worldwide. Mounting evidence suggests that transglutaminases (TGs), tissue TG (TG2) in particular, are involved in numerous molecular responses underlying the pathogenesis of cardiac diseases. The TG family has several intra- and extracellular functions in the human body, including collagen cross-linking, angiogenesis, cell growth, differentiation, migration, adhesion as well as survival. TGs are thiol- and calcium-dependent acyl transferases that catalyze the formation of a covalent bond between the γ-carboxamide group of a glutamine residue and an amine group, thus increasing the stability, rigidity, and stiffness of the myocardial extracellular matrix (ECM). Excessive accumulation of cross-linked collagen leads to increase myocardial stiffness and fibrosis. Beyond TG2 extracellular protein cross-linking action, mounting evidence suggests that this pleiotropic TG isozyme may also promote fibrotic diseases through cell survival and profibrotic pathway activation at the signaling, transcriptional and translational levels. Due to its multiple functions and localizations, TG2 fulfils critical yet incompletely understood roles in myocardial fibrosis and associated heart diseases, such as cardiac hypertrophy, heart failure, and age-related myocardial stiffness under several conditions. This review summarizes current knowledge and existing gaps regarding the ECM-dependent and ECM-independent roles of TG2 and highlights the therapeutic prospects of targeting TG2 to treat cardiac diseases.

Celiac Disease Revisited

Celiac disease (CD) is a systemic disease triggered by gluten ingestion in genetically predisposed individuals. It manifests primarily as an autoimmune enteropathy associated with specific circulating autoantibodies and a human leukocyte antigen haplotype (HLA-DQ2 or HLA-DQ8). It afflicts roughly 1% of the population, though the majority of patients remain undiagnosed. Diarrhea and malabsorption are classic manifestations of CD; however, both children and adults can be paucisymptomatic and present extraintestinal manifestations such as anemia, osteoporosis, and abnormal liver tests. CD screening is not recommended for the general population, and it should be focused on high-risk groups. CD diagnosis is challenging and relies on serological tests, duodenal histology, and genetic testing. Particularly difficult presentations to manage are seronegative patients, seropositive patients without villus atrophy, and patients who have started a gluten-free diet before the diagnostic workup. The only proven treatment is a lifelong gluten-free diet. We present an in-depth review on the physiopathology and management of CD, with a particular emphasis on diagnostic challenges.

Roles and potential clinical implications of tissue transglutaminase in cardiovascular diseases

Cardiovascular disease (CVD)-related mortality and morbidity are among the most critical disease burdens worldwide. CVDs encompass many diseases and involve complex pathogenesis and pathological changes. While research on these diseases has advanced significantly, treatments and their efficacy remain rather limited. New therapeutic strategies and targets must, therefore, be explored. Tissue transglutaminase (TG2) is pivotal to the pathological development of CVDs, including participating in the cross-linking of extracellular proteins, activation of fibroblasts, hypertrophy and apoptosis of cardiomyocytes, proliferation and migration of smooth muscle cells (SMCs), and inflammatory reactions. Regulating TG2 activity and expression could ensure remarkable improvements in disorders like heart failure (HF), pulmonary hypertension (PH), hypertension, and coronary atherosclerosis. In this review, we summarize recent advances in TG2: we discuss its role and mechanisms in the progression of various CVDs and its potential as a diagnostic and therapeutic target.

Repeat Biopsy to Assess Duodenal Healing in Children With Celiac Disease and Eosinophilic Gastrointestinal Disorders

The aim of the study was to determine the correlation between duodenal mucosal biopsies and tissue transglutaminase immunoglobulin A (tTG-IgA) levels in pediatric patients with biopsy-confirmed celiac disease (CD) and eosinophilic gastrointestinal disorders (EGID) who have had repeat duodenal biopsies after initiating a gluten-free diet.

Methods

A retrospective chart review was performed of children with CD and EGID seen at the Children's Hospital of Philadelphia between 2003 and 2018. Data collected included duodenal biopsy pathology, celiac serology including tTG-IgA, and symptom reports. Duodenal healing was defined as normal villous architecture and no intraepithelial lymphocytes. These data were compared with tTG-IgA level. Data were analyzed with Fisher exact test and t test methods.

Results

Thirty-nine patients had normal IgA and diagnoses of both CD and EGID. At second biopsy, 44% (17/39) of patients showed no histologic evidence of active CD and 36% (14/39) of patients had negative tTG-IgA values. Sixty percent (9/15) of patients with no evidence of CD on biopsy had abnormal tTG-IgA levels, and 57% (8/14) of patients with normal tTG-IgA levels had evidence of active disease on biopsy.

Conclusions

The data show that an abnormal tTG-IgA drawn after initiation of a gluten-free diet is not correlated with duodenal mucosal injury in pediatric patients with CD and EGID. This suggests that serologic surveillance with tTG-IgA is not sufficient to monitor CD intestinal healing in this patient cohort. Persistent elevations of tTG-IgA in CD patients with normal duodenal biopsies should prompt investigation into other potential causes.

Wait-and-See Approach or Gluten-Free Diet Administration-The Rational Management of Potential Coeliac Disease

Potential celiac disease (PCD) is a heterogeneous disease; only some patients develop full celiac disease (CD), characterised by advanced atrophic changes in the small intestine. Few accurate prognostic factors exist for the progression of PCD; therefore, therapeutic decisions should be made on an individual basis in each case. Patients with clinical gastroenterological or parenteral symptoms often benefit from a gluten-free diet, and those left on a diet containing gluten should receive clinical, serological and histopathological supervision.

HLA-DQ genotype and biochemical characterization of anti-transglutaminase 2 antibodies in patients with type 1 diabetes mellitus in Taiwan

Human Leukocyte Antigen (HLA)-DQ2 and HLA-DQ8 are genetic risk factors for Type 1 Diabetes Mellitus (T1DM) and Celiac disease (CD) in Caucasians, but their association with Taiwanese Han population is unknown. We screened 532 Taiwanese T1DM patients for CD biomarkers including anti-tissue transglutaminase (TGM2), anti-gliadin and anti-neoepitope antibodies (Abs), sequencing DQB1 genotypes, and characterized the TGM2 Abs. We report that 3.76% of Taiwanese patients had TGM2-Abs and all had no CD's symptoms. In contrast to Caucasian's CD patients, DQ2/DQ8 only constituted ~4/5 of TGM2-Abs positive patients, while the other ~1/5 patients belonged to different HLA genotypes. Either anti-gliadin or anti-neoepitope Abs coexisted with ~3/4 of TGM2-Abs positive patients that were likely due to gluten-ingestion, while the cause of TGM2-Abs production for other ~1/4 of patients was unknown. Purified anti-TGM2 IgA (TGA) and anti-TGM2 IgG (TGG) could bind on endothelial cells surface, recognized native better than denatured forms of TGM2, and TGA inhibited TGM2's transamidation activity by up to 80% but TGG had no effects. Epitope mapping of all TGM2-Abs positive sera demonstrated that TGM2-Abs had heterogeneity in specificities. This is the first study on the differences between Taiwanese Han group and Caucasian in HLA genotypes and properties of TGM2-Abs.

Increased mortality among men aged 50 years old or above with elevated IgA anti-transglutaminase antibodies: NHANES III

Background

Immunoglobulin A (IgA) antibodies to tissue transglutaminase (tTG) are the serologic test of choice for diagnosing celiac disease (CD). Our aim was to determine if elevated IgA anti-tTG were associated with increased mortality risk.

Methods

Stored serum samples of National Health and Nutrition Examination Survey (NHANES) III (1988–1992) were available for 6032 individuals aged 50 years old or above, which were screened for IgA anti-tTG, and if positive, for IgA endomysial antibodies. Mortality was determined from the National Death Index records through 2006. Hazard ratios were calculated through Cox proportional hazards regression.

Results

From a total of 6032, 85 participants tested positive for IgA anti-tTG (1.4 %) and 5947 tested negative. After a median follow-up of 13 years, IgA anti-tTG positive participants were at increased risk of death in both crude (HR = 1.68; 95 % CI = 1.30–2.18) and adjusted analyses (adjusted hazard ratio = 1.43; 95 % CI = 1.10–1.85) as compared to IgA anti-tTG negative participants. The excess mortality was restricted to IgA anti-tTG positive males (adjusted hazard ratio = 1.69 (95 % CI = 1.26–2.29), as opposed to a hazard ratio of 0.96 (95 % CI = 0.57–1.62) among IgA anti-tTG positive females. Although the most common cause of death in IgA anti-tTG positive participants was cardiovascular disease (36 %), the increased hazard ratio was only observed in respiratory cause of death as compared to IgA anti-tTG negative participants (adjusted hazard ratio = 5.11; 2.76–9.46).

Conclusion

Men aged 50 years old or above participants of NHANES III with elevated IgA anti-tTG antibodies had increased mortality risk. Elevated IgA anti-tTG antibodies could be a nonspecific marker of serious disease in older men.

Elderly Onset Celiac Disease: A Narrative Review

Celiac sprue is a chronic disease, which usually occurs in children and young adults. However, it can develop in any age group, and the prevalence is increasing even in the elderly population. The atypical patterns of clinical presentation in this age group sometimes can cause a delay in diagnosis. Given the lower sensitivity and specificity of serological tests in the aged population, clinical suspect often arises in the presence of complications (autoimmune disorders, fractures, and finally, malignancy) and must be supported by endoscopic and imaging tools. In this review, we highlight the incidence and prevalence of celiac disease in the elderly, the patterns of clinical presentation, diagnosis, and the most frequent complications, with the aim of increasing awareness and reducing the diagnostic delay of celiac disease even in the elderly population.

Cardiovascular disease in patients with coeliac disease: A systematic review and meta-analysis

BACKGROUND

Coeliac disease has been associated with an increased risk of cardiovascular disease in some studies, whereas other studies have shown no association. We performed a systematic review and meta-analysis of cardiovascular disease in celiac disease.

METHODS

Pubmed, Cinahl, EMBASE and Medline via Ovid were searched for relevant articles published until January 5, 2015. English-language articles on studies with more than 20 patients were included, and were quality rated using the GRADE risk of bias tool. We used random-effects models and assessed heterogeneity using the I(2) statistic.

RESULTS

Ten studies were relevant, reporting the risk of myocardial infarction, cardiovascular death and stroke in 33,128/32,903/32,466 coeliac disease patients respectively. Only one study examined celiac disease and a composite measure of cardiovascular disease and this study found a hazard ratio of 1.10 (95%CI 1.03-1.28). In a meta-analysis, we observed an increased risk of stroke (OR 1.11; 95%CI 1.02-1.20). The risks of myocardial infarction (OR 1.12; 95%CI 0.83-1.40) and cardiovascular death (OR 1.12; 95%CI 0.96-1.29) were similar but were estimated with less certainty. Heterogeneity was low for all outcomes except for myocardial infarction where it was moderate.

CONCLUSION

Coeliac disease was associated with a modestly increased risk of cardiovascular disease, but the evidence base is limited.

The side chain of glutamine 13 is the acyl-donor amino acid modified by type 2 transglutaminase in subunit T of the native rabbit skeletal muscle troponin complex

Subunit T of the native muscle troponin complex is a recognised substrate of transglutaminase both in vitro and in situ with formation of isopeptide bonds. Using a proteomic approach, we have now determined the precise site of in vitro labelling of the protein. A preparation of troponin purified from ether powder from mixed rabbit skeletal muscles was employed as transglutaminase substrate. The only isoform TnT2F present in our preparation was recognised as acyl-substrate by human type 2 transglutaminase which specifically modified glutamine 13 in the N-terminal region. During the reaction, the troponin protein complex was polymerized. Results are discussed in relation to the structure of the troponin T subunit, in the light of the role of troponins in skeletal and cardiac muscle diseases, and to the rules governing glutamine side chain selection by tissue transglutaminase.

Celiac disease diagnosis and management: a 46-year-old woman with anemia

Celiac disease is one of the most prevalent autoimmune gastrointestinal disorders, but as the case of Ms J illustrates, diagnosis is often delayed or missed. Based on serologic studies, the prevalence of celiac disease in many populations is estimated to be approximately 1% and has been increasing steadily over the last 50 years. Evaluation for celiac disease is generally straightforward and uses commonly available serologic tests; however, the signs and symptoms of celiac disease are nonspecific and highly heterogeneous, making diagnosis difficult. Although celiac disease is often considered a mild disorder treatable with simple dietary changes, in reality celiac disease imparts considerable risks, including reduced bone mineral density, impaired quality of life, and increased overall mortality. In addition, a gluten-free diet is highly burdensome and can profoundly affect patients and their families. For these reasons, care of individuals with celiac disease requires prompt diagnosis and ongoing multidisciplinary management.

Antibodies against deamidated gliadin peptides identify adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase

BACKGROUND

This study was done to evaluate the diagnostic utility of antibodies against deamidated gliadin peptides compared to traditional markers for coeliac disease.

AIM

To evaluate diagnostic utility of antibodies against deamidated gliadin peptide (DGP).

METHODS

Sera from 176 adults, referred for endoscopy without previous analysis of antibodies against tissue transglutaminase (tTG) or endomysium (EmA), were retrospectively analysed by ELISAs detecting IgA/IgG antibodies against DGP or a mixture of DGP and tTG, and compared with IgA-tTG and EmA. Seventy-nine individuals were diagnosed with coeliac disease.

RESULTS

Receiver operating characteristic analyses verified the manufacturers' cut-off limits except for IgA/IgG-DGP/tTG. In sera without IgA deficiency, the sensitivity was higher for IgA/IgG-DGP (0.85-0.87) compared with IgA-tTg (0.76) and EmA (0.61). All tests showed high specificity (0.95-1.00). Eighteen coeliac disease-sera were negative regarding IgA-tTG, nine of which were positive for IgA/IgG-DGP. Sera from coeliac disease-patients >70 years were more often negative for IgA-tTG (50%) and IgA/IgG-DGP (36%) than younger patients (15% and 8% respectively) (P < 0.01). Three of the four IgA-deficient patients were positive in the IgA/IgG-DGP assay.

CONCLUSIONS

In this study of patients unselected regarding IgA-tTg/EmA, thus unbiased in this respect, IgA/IgG-DGP identified adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase. Serology is often negative in elderly patients with coeliac disease; a small bowel biopsy should therefore be performed generously before coeliac disease is excluded.

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.

Suboptimal performance of IgG anti-tissue transglutaminase in the diagnosis of celiac disease in a tropical country

Serological tests using human IgA-anti-tTG have been reported to have high sensitivity and specificity in diagnosis of celiac disease. There is a paucity of data on the use of human IgG-anti-tTG in diagnosis of celiac disease. Ninety-two patients with clinical suspicion of celiac disease who underwent duodenal mucosal biopsy and celiac serology using human IgG-anti-tTG were included in this retrospective study. Diagnostic accuracy of human recombinant IgG-anti-tTG serological test for celiac disease was evaluated. Indications for celiac serological testing were diarrhea (92.3%), hypoalbuminemia (39.1%), and anemia (35.9%). Eighteen patients were diagnosed with having celiac disease and 14 (77.8%) of them were IgG-anti-tTG positive. Of the remaining 74 patients, eight (10.8%) were false-positive for IgG-anti-tTG. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of IgG-anti-tTG in celiac disease were 77.8, 89.1, 63.6, 94.2, and 87%, respectively. Human IgG-anti-tTG alone does not perform well as a diagnostic tool for celiac disease. The utility of anti-endomysial antibodies in a similar clinical setting needs to be evaluated.

Spontaneous autoimmune myocarditis and cardiomyopathy in HLA-DQ8.NODAbo transgenic mice

Most individuals have viral infections at some point in their life, however, only few develop autoreactivity to cardiac myosin following infection suggesting a genetic predisposition. Population studies have shown that among all the genetic factors linked with autoimmune disease development, MHC class II genes are the most significant genetic factors. Experimental autoimmune myocarditis resembling human Dilated cardiomyopathy can be induced in susceptible mice by infection with coxsackie virus as well as immunization with purified foreign and murine cardiac specific a-myosin. We generated transgenic mice lacking endogenous class II molecules, HLA-DR3.Abo and HLA-DQ8.Abo transgenic mice in NOD and HLA-DQ8.Abo in B10 background, to study the role of MHC in spontaneous autoimmunity. The HLA molecules in these mice are expressed on cell surface and can positively select CD4+ T cells expressing various Vb T cell receptors. NOD.DQ8 female mice spontaneously developed myocarditis and dilated cardiomyopathy. Histopathology of heart revealed mononuclear infiltrate consisting of CD4 and Mac-1+ cells and myocyte necrosis. NOD.DQ8 mice showed cellular and humoral autoreactive response to self cardiac myosin.. Depletion of CD8 and CD4 + cells suggested that CD8 T cells may act as regulatory cells while CD4 cells are required as effector cells. NOD.DR3 and B10.DQ8 mice did not develop any cardiac pathology suggesting DQ8 is required for predisposition to the spontaneous autoreactivity while NOD background influences onset and progression of disease. Thus these mice provide powerful tools to understand the role of HLA class II molecules in predisposition and onset of human diseases and to develop immunotherapy.

Increased prevalence of anti-gliadin antibodies and anti-tissue transglutaminase antibodies in children with cerebral palsy

AIM AND OBJECTIVE

The aim of the study was to investigate whether there is any association between cerebral palsy (CP) and celiac disease (CD) in children.

PATIENTS AND METHODS

Ninety children between 18 months and 18 years of age (median 9 years) with CP were included. Antibodies (IgA and IgG) against gliadin (AGA), endomysium (EMA), and tissue transglutaminase (tTG) were measured. Children with elevated levels of these antibodies were offered a small-bowel biopsy.

RESULTS

Thirty-nine children showed an elevated level of 1 or more of the tested antibodies (43%). None had raised EMA antibodies. Presence of tetraplegia or dyskinesia was associated with increased antibody levels (P=0.045), as was a more severe functional type of CP (P=0.008). Children with elevated antibodies had a lower body weight (P=0.049), height (P=0.041), and body mass index (BMI) (P=0.014). Small-bowel biopsies were performed in 27 out of 39 children; 1 had CD and 2 had intraepithelial lymphocytosis.

CONCLUSIONS

A large number of children with CP had elevated AGA and/or anti-tTG. Because these elevations were associated with lower weight, height, and BMI, it seemed of interest to speculate on how these findings correlated to CP and CD. However, we found no correlation between CP and CD.

Increased prevalence and mortality in undiagnosed celiac disease

BACKGROUND & AIMS

The historical prevalence and long-term outcome of undiagnosed celiac disease (CD) are unknown. We investigated the long-term outcome of undiagnosed CD and whether the prevalence of undiagnosed CD has changed during the past 50 years.

METHODS

This study included 9133 healthy young adults at Warren Air Force Base (sera were collected between 1948 and 1954) and 12,768 gender-matched subjects from 2 recent cohorts from Olmsted County, Minnesota, with either similar years of birth (n = 5558) or age at sampling (n = 7210) to that of the Air Force cohort. Sera were tested for tissue transglutaminase and, if abnormal, for endomysial antibodies. Survival was measured during a follow-up period of 45 years in the Air Force cohort. The prevalence of undiagnosed CD between the Air Force cohort and recent cohorts was compared.

RESULTS

Of 9133 persons from the Air Force cohort, 14 (0.2%) had undiagnosed CD. In this cohort, during 45 years of follow-up, all-cause mortality was greater in persons with undiagnosed CD than among those who were seronegative (hazard ratio = 3.9; 95% confidence interval, 2.0-7.5; P < .001). Undiagnosed CD was found in 68 (0.9%) persons with similar age at sampling and 46 (0.8%) persons with similar years of birth. The rate of undiagnosed CD was 4.5-fold and 4-fold greater in the recent cohorts, respectively, than in the Air Force cohort (both P < or = .0001).

CONCLUSIONS

During 45 years of follow-up, undiagnosed CD was associated with a nearly 4-fold increased risk of death. The prevalence of undiagnosed CD seems to have increased dramatically in the United States during the past 50 years.

Symposium 1: Joint BAPEN and British Society of Gastroenterology Symposium on ‘Coeliac disease: basics and controversies’ Coeliac disease in the twenty-first century

Coeliac disease (CD), traditionally perceived as a rare childhood condition presenting with malabsorption, is instead an autoimmune multisystem disorder usually presenting in adulthood, affecting ⩾1% of the population and linked to the genetic expression of human leucocyte antigens (HLA) DQ2 and DQ8. Presentation occurs most often in the 40–60 years age-group, but potentially at any age. Symptoms attributable to the gut or to malabsorption may be mild, non-specific or absent; under one-third of patients have diarrhoea and almost half are overweight. Histological diagnosis no longer requires small intestine villous atrophy. The Marsh classification recognizes increased intraepithelial lymphocytes and crypt hyperplasia with intact villi as part of the gluten enteropathy spectrum, while some individuals have more subtle abnormalities identified only on electron microscopy. Serological testing for CD autoantibodies (to endomysium and tissue transglutaminase) has revolutionized diagnosis, shifting the process towards primary care. However, a substantial number of patients with CD are seronegative, particularly those without villous atrophy. The autoantibody to endomysium may be produced before histological change. The immune response to transglutaminase is crucial to the disease process. An exciting new development is the link between antibodies to organ-specific transglutaminases and clinical presentation; transglutaminases 2 (gut), 3 (skin) and 6 (nervous system). Negative testing for CD does not preclude its development later and HLA testing may allow ‘once and for all’ exclusion. In conclusion, an increasing proportion of patients with CD do not meet the ‘classic’ picture of malabsorption, positive serological testing and villous atrophy. Insisting on all these criteria for diagnosis will result in under diagnosis.

Comparison of commercially available serologic kits for the detection of celiac disease

BACKGROUND

The sensitivity and specificity of current antihuman tissue transglutaminase (tTG) IgA assays used to detect celiac disease reportedly approach 100%. In addition, the sensitivity of new generation deamidated gliadin peptide (alpha-DGP) antibody assays has also been reported to be similar to the tTG IgA assays. In routine clinical practice, however, the sensitivities and specificities of these tests for diagnosing celiac disease seem to be lower.

AIM

We analyzed sensitivities and specificities of 4 IgA tTG and 3 deamidated gliadin peptide (alpha-DGP) kits.

METHODS

The performance of 4 tTG IgA assays, A: Inova (Hu red blood cell), B: Binding site (rHu Ag), C: Eurospital (rHu Ag), D: Immco (rHu Ag) and 3 Inova alpha-DGP assays, E: alpha-DGP-IgA, F: alpha-DGP-IgG, and G: alpha-DGP-IgA+G was evaluated using sera from different subsets of celiac disease patients and controls; group 1: active celiac disease n=28, group 2: gluten-free diet n=54, group 3: healthy controls n=40, group 4: disease controls n=57(Crohn's disease n=17, chronic hepatitis n=40).

RESULTS

Using the manufacturer's cut-off values, the sensitivities and specificities of different kits ranged from 71.4% to 96.4% and 87.5% to 100%, respectively. When group 1 was compared with disease controls, sensitivities remained the same but specificities decreased. Receiver operating characteristic plot derived cut-off values modified decision thresholds in all assays except kit (G). Kappa analysis demonstrated variable degrees of agreement. All assays demonstrated higher sensitivities for patients with higher grades of villous atrophy.

CONCLUSIONS

Overall sensitivity was at or below 90%, which is lower than that reported in the literature. Performance of the recombinant and red blood cell antigen-based tTG assays was similar, whereas the alpha-DGP assays demonstrated lower values. Receiver operating characteristic plot derived cut-off values altered test results. Many factors affect the results of these tests and clinicians should be aware of their limitations.

What is the role of serologic testing in celiac disease? A prospective, biopsy-confirmed study with economic analysis

BACKGROUND & AIMS

The optimal serologic tests for the detection of celiac disease and follow-up assessment remains controversial. Our aim was to evaluate all current immunologic assays for diagnosing celiac disease using the gold standard of duodenal biopsy. We also assessed whether tissue transglutaminase (tTG) antibody is a quantitative marker for histologic severity.

METHODS

Consecutive adult patients referred for gastroscopy without a previous known diagnosis of celiac disease were recruited (group 1). Concurrently, patients with a known diagnosis of celiac disease on a gluten-free diet for more than 1 year undergoing repeat duodenal biopsy were identified (group 2). All patients had duodenal biopsies and serologic analysis performed for immunoglobulin(Ig) A and antibodies to human immunoglobulin (Ig)A-tTG, IgA-gliadin, IgG-gliadin, and IgA-endomysial antibody.

RESULTS

Two thousand patients were recruited in the first group. Seventy-seven (3.9%) patients were diagnosed with new celiac disease. The sensitivity, specificity, positive predictive value, and negative predictive value for IgA tTG were 90.9%, 90.9%, 28.6%, and 99.6%. When adopting a 2-step approach using tTG first and then EMA the sensitivity, specificity, positive predictive value, and negative predictive value was 85.7%, 98.6%, 71.7%, and 99.7%, respectively. The use of nondeamidated IgA/IgG gliadin antibodies conferred no additional diagnostic benefit when considering the detection of adult celiac disease. In the second group 48 patients with celiac disease on a gluten-free diet were identified. Sixteen of 48 of these patients had persisting villous atrophy, but 7 of 16 (44%) had a normal tTG level.

CONCLUSIONS

IgA tTG alone is a sensitive marker for celiac disease. A normal tTG level does not predict recovery of villous atrophy in patients with celiac disease on a gluten-free diet.

Antitissue transglutaminase antibodies in acute coronary syndrome: an alert signal of myocardial tissue lesion?

BACKGROUND AND AIM

Antitransglutaminase, previously considered identical to antiendomysial in coeliac sprue (CS), have been reported in end-stage heart failure. To clarify the above-mentioned data, we evaluated these antibodies in a cohort of cardiological patients with respect to troponin I, creatine kinase (CK), MB fraction creatine kinase (CK-MB mass) and myoglobin.

METHODS

Forty-one patients with acute coronary syndrome (ACS), 39 with dilated cardiomyopathy (DCM), 45 with CS and 58 blood donors (BDs) were evaluated. Antitransglutaminase and antiendomysial antibodies were tested in serum of the patients being studied.

RESULTS

High-positive antitransglutaminase values were found in CS, whilst low-positive values were also found in ACS and DCM. In patients at the second ACS, antibody levels were higher than in those at the first cardiac event. In patients with infarct Q, antitransglutaminase were higher than those in infarct non-Q, in which antibody levels were higher than those in unstable angina. A correlation between antitransglutaminase and troponin I, CK, CK-MB mass and myoglobin was found. Finally, antibody levels rose to reach a peak at 30 days from the cardiac event, whereas after further 150 days, approached the values of BDs. Antiendomysial were detectable only in CS.

CONCLUSIONS

Data highlight that antitransglutaminase can occur in cardiological patients, and that these antibodies are related to the severity/extent of the myocardial tissue lesion. This feature suggests a loss of specificity for antitransglutaminase in CS. Furthermore, the possibility of employing these antibodies in the long-term follow-up of ACS, could become an object of interesting discussion.

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.

Humoral immune response to tissue transglutaminase is related to epithelial cell proliferation in celiac disease

BACKGROUND & AIMS

Tissue transglutaminase (tTG) autoantibodies are markers of celiac disease, and the enzyme is required for several crucial biological processes. The aim of this study was to determine whether these autoantibodies are involved in the pathogenesis of the mucosal lesion typical of celiac disease.

METHODS

Using rhodamine-conjugated phalloidin staining, we evaluated whether tTG antibodies, both commercially available and cloned from patients with celiac disease, cause cytoskeletal changes in Caco-2, MCF7, and NIH 3T3 cells. We monitored cell levels of bromodeoxyuridine incorporation to determine whether tTG autoantibodies are able to induce NIH 3T3 fibroblasts and epithelial mucosal cells into S phase.

RESULTS

Treatment with tTG antibodies caused a dose-dependent increase of membrane ruffling in Caco-2, MCF7, and NIH 3T3 cells. It also dose-dependently induced G(0)-synchronized NIH 3T3 fibroblasts into S phase but did not affect the rate of apoptosis. Similarly, tTG antibodies induced S-phase entry of epithelial cells in cultured intestinal biopsy specimens from patients with celiac disease. They did not affect biopsy specimens from patients without celiac disease.

CONCLUSIONS

Our results suggest that tTG autoantibodies per se, by interacting with the extracellular membrane-bound transglutaminase, may play an important role in epithelial cell proliferation in celiac disease.

Roles of transglutaminases in cardiac and vascular diseases

All transglutaminases share the common enzymatic activity of transamidation, or the cross-linking of glutamine and lysine residues to form N epsilon (gamma-glutamyl) lysyl isopeptide bonds. The plasma proenzyme factor XIII is responsible for stabilizing the fibrin clot against physical and fibrinolytic disruption. Another member of the transglutaminase family, tissue transglutaminase or TG2 is abundantly expressed in cardiomyocytes, vascular cells and macrophages. The transglutaminases have a variety of functions independent of their transamidating activity. For example, TG2 binds and hydrolyzes GTP, thereby fostering signal transduction by several G protein coupled receptors. Accumulating evidence points to novel roles for factor XIII and TG2 in cardiovascular biology including: (a) modulating platelet activity, (b) regulating glucose control, (c) contributing to the development of hypertension, (d) influencing the progression of atherosclerosis, (e) regulating vascular permeability and angiogenesis (f) and contributing to myocardial signaling, contractile activity and ischemia/reperfusion injury. In this review, we summarize the cardiovascular biology of two members of the family of transglutaminases, Factor XIII and TG2.

Utility in clinical practice of immunoglobulin a anti-tissue transglutaminase antibody for the diagnosis of celiac disease

BACKGROUND & AIMS

The diagnosis of celiac disease often relies on the anti-tissue transglutaminase (tTG) antibody test. The aim of this study was to evaluate its sensitivity and specificity in clinical practice with the use of commercial laboratories, in which the test characteristics might differ from research laboratories.

METHODS

We identified 122 patients with suspected celiac disease who had anti-tTG antibody serologies as well as upper endoscopy with duodenal biopsies. Those with celiac disease were classified as either classic (with diarrhea or other symptoms of malabsorption) or silent (asymptomatic). Biopsies from celiac disease patients were classified as either partial (Marsh IIIA) or total (Marsh IIIB or IIIC) villous atrophy.

RESULTS

The overall sensitivity, specificity, and positive and negative predictive values of the anti-tTG antibody test were 70.6%, 65.0%, 91.1%, and 30.2%, respectively. The sensitivity was 90.0% for patients with total villous atrophy and 42.3% for patients with partial villous atrophy (P < .0001). There were differences in both sensitivity and specificity between the 2 most commonly used commercial laboratories. The sensitivity for Lab #1 was 40.0% versus 86.4% for Lab #2 (P < .0001). The specificity for Lab #1 was 100.0%, and it was 41.7% for Lab #2 (P = .02).

CONCLUSIONS

The sensitivity of the anti-tTG antibody in clinical practice is not as high as previously reported in research laboratories. The sensitivity is significantly lower in patients with partial villous atrophy. There is also significant variability in test characteristics among major commercial laboratories in the United States. These results need to be confirmed in prospective studies.

Celiac disease prevalence in Brazilian dilated cardiomyopathy patients

Celiac disease (CD) is a permanent condition of gluten intolerance and a number of autoimmune diseases have been associated with it. In the past few years, a relation between CD and dilated cardiomyopathy (CM) was described in Europe and United States. The aim of this study was to evaluate the prevalence of CD among south Brazilian precardiac transplant patients with advanced CM. A total of 74 patients on a list for heart transplantation were evaluated for the presence CD. The presence of anti-endomisial antibody (IgA-EmA) was determined by indirect immunofluorescence and for the anti-transglutaminase antibody (IgA anti-h-tTG) by ELISA. Serologically positive patients were submitted to upper endoscopy with intestinal biopsy. Two individuals (2.63%) were positive for IgA-EmA and 5 (6.75%) for IgA anti-h-tTG; 1 (1.35%) had both tests positive. Histologic confirmation of CD occurred only in the IgA-EmA positive patients. In conclusion, data from the present study allows recommend the screening for CD in patients with CM using IgA-EmA test as the method of choice.

Mortality excess in individuals with elevated IgA anti-transglutaminase antibodies: the KORA/MONICA Augsburg cohort study 1989-1998

OBJECTIVES

Immunoglobulin A (IgA) autoantibodies to tissue transglutaminase (tTG) are commonly used for screening and diagnosing of celiac disease. We examined the hypothesis that elevated IgA anti-tTG antibodies were associated with higher all-cause mortality risk.

METHODS

The cohort, 2333 men and 2300 women, was based on the follow-up of participants of a representative population-based survey in Southern Germany (KORA/MONICA Augsburg project) conducted in 1989-1990. The endpoint for the vital status with cause of death was the year 1998. The sera drawn at baseline and stored at -80 degrees C, were recently screened with an IgA enzyme-linked immunosorbent assay (ELISA) using human recombinant tTG. Age-standardized mortality rates and age-adjusted hazard ratios were calculated.

RESULTS

From the 4633 sera analyzed, 63 had an IgA anti-tTG concentration>or=7 AU/ml. Of these 63 individuals, 15 died between 1989 and 1998. The age-adjusted hazard ratio (HRa) of all-cause mortality was 1.86 (95% CI: 1.01-3.41) and 3.92 (95% CI: 1.44-10.71) for men and women, respectively. The excess of cancer mortality was even higher with an HR(a) of 2.47 (95% CI: 0.89-6.83) in men and of 6.65 (95% CI: 2.04-21.63) in women.

CONCLUSIONS

Individuals with elevated IgA anti-tTG antibodies had a highly increased mortality risk, particularly due to cancer. New studies are necessary to clarify if this increased risk is due to undiagnosed celiac disease or/and if this elevated IgA anti-tTG antibodies level is a marker of serious diseases like cancer, chronic liver disease or end-stage heart failure.

Comparison of six human anti-transglutaminase ELISA-tests in the diagnosis of celiac disease in the Saharawi population

AIM: Celiac disease (CD) is an enteropathic disorder very prevalent in Saharawi people. Our aim was to investigate the diagnostic accuracy of six human tissue transglutaminase (tTG) based ELISA tests in Saharawi CD patients.

METHODS: Fifty-two CD patients and 23 controls were selected from the Saharawi refugee camps in Tinduf. CD patients were divided into two groups according to their anti-endomysium (EmA) status: 41 EmA positive and 11 EmA negative. Sera from patients and controls were tested for human tTG using six commercial ELISA kits. We used receiver operating characteristics (ROC) curves and areas under the curve to compare the diagnostic accuracies of the six assays.

RESULTS: In general, there are differences in the sensitivity and specificity of the human tTG ELISA assays used. Diagnostic accuracy of tests was significantly improved by adjusting the cut-off thresholds according to ROC plot analysis; the correction of the cut-off with the employment of the ROC curve analysis modifies the decision limit in more than 50% in five of the six kits evaluated.

CONCLUSION: Some of the human tTG ELISAs used in this study have a diagnostic accuracy similar to EmA determination for diagnosis of CD in Saharawi people. However, it is necessary to select the assay with a higher sensitivity and specificity, and recalculate the cut-off threshold using samples from the referral population.

Diagnosis of coeliac disease

The diagnosis of coeliac disease depends on the finding of characteristic, though not specific changes, of intraepithelial lymphocytosis, crypt hyperplasia and various degrees of villous height reduction identified in duodenal biopsies of individuals ingesting a gluten containing diet, together with symptomatic and histologic improvement on gluten withdrawal. Serologic testing has become the main mode of determining who will undergo biopsy. The IgA endomysial antibody and IgA tissue transglutaminase antibody have approximately 90% sensitivity and specificity, though there are reports of lower sensitivity and specificity in the clinical practice setting. This is due to lower titers of these antibodies in the presence of lesser degrees of mucosal damage. The widespread availability of serologic tests for coeliac disease allows the diagnosis to be considered by any physician. Gastroenterologists will be required to interpret the results of serologic tests and perform duodenal biopsies when indicated. Pathologists likewise need to be better acquainted with the more subtle changes of cell mediated immunity within the mucosa that are suggestive of underlying gluten sensitivity.

Is immunoglobulin A anti-tissue transglutaminase antibody a reliable serological marker of coeliac disease?

BACKGROUND

Anti-tissue transglutaminase (tTG) antibody is being used increasingly as a diagnostic tool in the serological investigation of coeliac disease. However, positive predictive values of immunoglobulin A (IgA) anti-tTG for coeliac disease in prospective studies have been disappointing and false-positive results are reported.

OBJECTIVE

To assess the clinical utility of cascade testing for anti-tTG and anti-endomysium antibody (AEA).

PATIENTS

Two unselected retrospective cohorts from routine diagnostic investigation for possible gluten sensitive enteropathy: group 1 comprised 57 cases seropositive for anti-tTG and group 2 comprised 52 cases seronegative for anti-tTG. In both groups, all cases had also undergone small-intestinal biopsy.

METHODS

Patients were assessed for the presence of IgA anti-tTG by enzyme-linked immunosorbent assay and for IgA AEA by immunofluorescence.

RESULTS

The positive predictive value of IgA anti-tTG for biopsy-confirmed coeliac disease was 54%. The positive predictive value of dual positivity for anti-tTG and AEA was 97%. The negative predictive value of IgA anti-tTG was 100%.

CONCLUSIONS

The data presented here support the use of IgA anti-tTG as an initial screen for coeliac disease. Coeliac disease is unlikely when IgA anti-tTG is absent. However, many false-positive results are seen, and clinical utility and diagnostic efficiency are improved markedly if positive results are confirmed with the more accurate, but labour-intensive, AEA assay.

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.

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.

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.