Reaction of human non-collagenous polypeptides with coeliac disease autoantibodies

Changing Pattern of Childhood Celiac Disease Epidemiology: Contributing Factors

Up until the 1960s and 1970s, diarrhea, malabsorption syndrome, and failure to thrive were the presenting symptoms and signs of celiac disease (CD) in young infants; however this disease was also at the same time reported to be disappearing. Indeed, clinical childhood CD was seen to transform into a milder form, resulting in an upward shift in age at diagnosis during the 1970s (and years later for many countries). This changing pattern of CD presentation then altered the epidemiology of the disease, with major differences between and within countries observed. An awareness of the changing clinical nature of CD and use of case-finding tools to detect even clinically silent CD became an important factor in this changing epidemiology. Countries report both low and high prevalence but it seems to be on the increase resulting in a population-based level of 1-2%. This paper discusses the potential causes and environmental factors behind these observed clinical changes, identifying new clues from different studies published at the time this transformation took place. For instance, it was found that breastfeeding postponed the diagnosis of the disease but did not altogether prevent it. Moreover, gluten introduction at a young age, specifically at the mean age of 2 months, seemed to also have a clear impact in inducing malabsorption syndrome and failure to thrive in young infants in addition to other factors such as gluten intake volume and type of cereal present in the weaning food. Further, the impact of cow's milk and its high osmolarity might have played an important role; humanized milk formulas were not yet invented. Future epidemiological studies on the contributing environmental factors to the shift in CD presentation are thus recommended for countries in which these changing clinical features are still being observed.

Diagnosing Celiac Disease: Towards Wide-Scale Screening and Serology-Based Criteria?

Celiac disease is one of the most common food-related chronic disorders in children. Unfortunately, this multifaceted disease is challenging to recognize and remains markedly underdiagnosed. Screening of either known at-risk groups or even the whole population could increase the suboptimal diagnostic yield substantially. Many recent guidelines recommend screening of at least selected risk groups, but more wide-scale screening remains controversial. The increasing prevalence of celiac disease and the development of autoantibody assays have also led to a gradual shift in the diagnostics towards less invasive serology-based criteria in a subgroup of symptomatic children. The main open questions concern whether these criteria are applicable to all countries and clinical settings, as well as to adult patients. On the other hand, widening screening and the mistaken practice of initiating a gluten-free diet before the appropriate exclusion of celiac disease increase the number of borderline seropositive cases, which may also challenge the classical histopathological diagnostics. Sophisticated diagnostic methods and a deeper understanding of the natural history of early developing celiac disease may prove useful in these circumstances.

Association of celiac disease with non-cirrhotic portal fibrosis

Both celiac disease and non-cirrhotic portal fibrosis are known to be associated with various autoimmune diseases and have numerous immunological abnormalities. Herein two patients with celiac disease having associated non-cirrhotic portal fibrosis are reported. An autoimmune link between the two conditions is likely to explain coexistence in the same patient.

Gliadin as a stimulator of innate responses in celiac disease

In celiac disease (CD) we have the prototype of an immune mediated response dominated by the activation of the adaptive immune system and in particular of CD4+ HLA class II restricted T cells. Various seminal studies have established the precise mechanism of how antigen (prolamine) specific activation of CD4+ mucosal T cells occurs. Thus, CD is a condition in which T cells and their activation is the essential hinge in the pathogenic process. These functional studies have provided the explanation for the genetic association between CD and certain HLA alleles (HLA DQ2 and DQ8). These genetic, molecular and functional studies have permitted the clarification of a powerful Th1 dominated pro-inflammatory response that characterises the small intestine of active CD patients. Despite this unassailable set of information and reports there are some intriguing points that have been raised by a series of studies which have indicated that CD is not only defined by an aberrant prolamine-induced activation of the adaptive immune system. New evidence and re-assessments of old studies, point to a more complex pathogenic cascade, which may help to unravel some of the residual obscure points of CD pathogenesis. Here, we outline the current concepts that indicate a direct involvement of the adaptive immune system and we discuss all the evidence supporting a direct activation of the innate immune system by fragments of prolamines, which are not recognized T cell epitopes and how they could influence CD. The gliadin-induced activation of the 'innate' immune system might also have a significant role in the induction and persistence of many CD complications and most definitively for the most aggressive one, namely mucosal T cell lymphomas. We further suggest a novel way to harness the unwanted immune response to toxic prolamine, and thus indicate new potential therapeutic strategies to treat or at least control CD.

Endocrine autoantibodies

The autoantibody assays that exist and that are being refined are of increasing importance to a broad spectrum of endocrine disorders. This is particularly true for type IA diabetes, which is one of the best-studied organ-specific autoimmune diseases. Autoantibodies are used as valuable markers in prediction and prevention studies of type IA diabetes. Autoantibodies related to other endocrine organs are also important because multiple related autoimmune endocrine and non-endocrine disorders are increased in frequency in patients and their families with autoimmunity. The availability of highly sensitive and specific autoantibody assays for the various endocrine disorders can allow physicians to better diagnose and promptly treat these conditions.

Celiac disease: a model autoimmune disease with gene therapy applications

Gene therapy (GT) is still at the 'experimental' stage and some recent setbacks have cooled the potential use of this therapeutic tool even in life-threatening conditions. However, this therapeutic approach has a potential, which is not limited to disease for which we have not other option. There are increasing evidence that GT will be soon used in diseases that are not life threatening. One group of diseases that can benefit from GT is the autoimmune one. Several experimental animal models have indicated the efficacy (proof of principle) of GT. In the present review, we have addressed the possibility that even extremely benign autoimmune-like diseases such as Celiac Disease (CD) might one day profit from this type of therapy. We further point that in conditions such as CD, where the trigger is well known and the pathogenic cascade is relatively well defined, a situation not common in autoimmunity, we can even have a better situation where to explore and use GT to control disease initiation and progression. Once the risks that are still intrinsic to GT will have been reduced the therapeutic options we outline in the present review might not appear too far from reality.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

B cell epitopes of gliadin

A phage displayed dodecapeptide library and synthetic octapeptides spanning the complete sequence of alpha- and gamma-type gliadin and overlapping in six amino acids (pepscan) were screened for binding to human gliadin antibodies (AGA). Phage display experiments led to four sequences recognized with significantly higher frequency by sera with raised IgA-AGA titres than by control sera. All these peptides contained the core sequence PEQ. Pepscan experiments revealed binding of AGA to five prominent regions: (i) QXQPFP (binding to IgG and IgA, X representing P, Q, and L); (ii) IPEQ (IgG) and WQIPEQ (IgA); (iii) FFQP (IgG) and QGXFQP (IgA, X representing F and S); (iv) PQQLPQ (IgG and IgA), all in alpha-type gliadin; and (v) QPQQPF (IgG and IgA) in gamma-type gliadin. In two of the sequences (QPQQPF and QQQPFP), substitution of Q by E resulting in QPEQPF and QEQPFP, respectively, increased significantly binding of AGA from sera of patients with biopsy-proven or suspected coeliac disease (CoD), all positive for endomysium antibodies (EmA). In contrast, binding of sera with high AGA titre from EmA-negative patients (CoD and dermatitis herpetiformis excluded) was not enhanced by this substitution. Thus, AGA directed against these modified epitopes can be regarded as specific for CoD. This is the first study demonstrating that deamidation of gliadin improves reactivity of AGA of CoD patients.

Importance of gluten in the induction of endocrine autoantibodies and organ dysfunction in adolescent celiac patients

OBJECTIVE

It is well known that a high number of celiac patients may develop autoantibodies against endocrine glands, but it has not yet been clarified if this increased autoimmune response and the impaired organ function that can develop may be related to the presence or absence of gluten in the diet. The aim of the present study was to evaluate the effect of gluten on the autoimmunity and function of the endocrine glands in adolescent celiac patients.

METHODS

To clarify this aspect we investigated 44 patients (28 females), aged 11-20 yr (15.21+/-2.7 yr): 25 (mean age, 15.1+/-2.2 yr) on a gluten-free diet (treated patients) and 19 (mean age 15.4+/-2.9 yr) with a diet containing gluten (untreated patients). Forty adolescent subjects, aged 14-19 yr (mean age, 14.9+/-2.7 yr), of whom 20 were females, were studied as controls. Antibodies against the thyroid, adrenal, and pancreas were evaluated. Thyroid-stimulating hormone FT3, FT4, T3, T4, dehydroepiandrosterone sulphate, 17-OH progesterone, and cortisol, analyzed basally and 60 min after intravenous ACTH stimulation, were assayed to evaluate thyroid and adrenal function. The fasting glycemia level was used to evaluate the endocrine pancreas function. An ultrasonogram of the thyroid gland was performed on all patients. HLA class II typing for DR3 and DQB1 was performed in 32 of 44 patients.

RESULTS

Seven of 44 (15.9%) patients were positive for antibodies against peroxidase. Six of 44 (13.6%) were positive for antibodies against thyreoglobulin and four of them also showed positive antibodies against peroxidase. Therefore, in nine of 44 at least one antibody directed against thyroid tissue was positive. Seven of 44 (15.9%) were positive for antibodies against islet cell, one of 44 (2.3%) positive for antibodies against glutamic acid decarboxilase, one of 44 (2.3%) positive for antibodies against insulin, and none for antibodies against islet cell- 512bdc. In 15 of 44 (34%) at least one antibody against an endocrine tissue was positive. The genotype DR3 was found in 21 of 32 (65.6%) celiac patients (10 in the untreated and 11 in the treated group, respectively) and the genotype DQB1*02 (DQ2) was found in 30 of 32 (93.8%) patients (16 in the treated and 14 in the untreated group, respectively). DHA-S values were significantly lower in the untreated (30.5+/-28.5 microg/dl) than in the treated group (61.3+/-59.4 microg/dl, p < 0.05), and both showing significantly (p < 0.01) lower levels with respect to the controls (161+/-52 microg/dl). One patient showed diabetes, another one clinical hypothyroidism (thyroid-stimulating hormone > 6), and two patients showed preclinical hypothyroidism. Interestingly, at least one antibody was positive in 10 of 19 untreated patients (52.6%) but only in five of 25 treated patients (20%), with a significantly different distribution (p < 0.001) between the two groups and without differences in the HLA genotype. The ultrasonographic evaluation of the thyroid resulted in a pathological score in six patients of the 44 examined (13.6%), suggesting the presence of thyropathy.

CONCLUSIONS

The main results of this study are the high incidence of thyroid and pancreatic antibodies, and the possible role of gluten in the induction of the antibodies as well as, in few cases, the consequent organ dysfunction.

Antibodies to gliadin, endomysium, and tissue transglutaminase for the diagnosis of celiac disease

BACKGROUND

Tissue transglutaminase has recently been identified as the main autoantigen recognized by antiendomysial antibodies in celiac disease. Serum immunoglobulin (Ig)A antibodies to tissue transglutaminase (tTG-ab) determined by an enzyme-linked immunosorbent assay (ELISA) technique have been reported to correlate closely with IgA antiendomysial antibodies (EMA). The purpose of this study was to assess the sensitivity, specificity, and predictive value of tTG-ab measured by a commercially available ELISA technique, compared with those of EMA and IgA antigliadin antibodies (AGA) for the diagnosis of celiac disease.

METHODS

Twenty-seven serum samples were obtained from patients with untreated celiac disease, 37 from patients who had had gluten withdrawn from their diets for varying time spans, and 34 from control subjects without celiac disease. All were younger than 14 years. Presence of tTG-ab and AGA was determined by ELISA and of EMA by indirect immunofluorescence.

RESULTS

Twenty-six of 27 serum samples obtained from patients at the time of diagnosis of celiac disease were AGA positive. All 27 (concordance rate 100%) were positive for EMA and tTG-ab. Of the 34 control subjects, 1 was for AGA and 2 for tTG-ab. All 34 were negative for EMA. Sensitivity, specificity, positive predictive value, and negative predictive value within this group were, for tTG-ab: 100%, 94%, 93%, and 100%, respectively; for EMA: all four indexes were 100%; and for AGA: 96%, 97%, 96%, and 97%, respectively. Of the 37 with treated celiac disease, 2 were AGA positive, 9 were EMA positive, and 6 were tTG-ab positive. The concordance rate between EMA and tTG-ab was 100% in the group with untreated celiac disease, 94% in the control subjects, and 76% in the group with treated celiac disease.

CONCLUSIONS

Immunoglobulin A antibodies to tissue transglutaminase are new, highly sensitive, and specific markers of celiac disease. They can be determined easily by an accurate, comparatively cheap technique and thereby may advantageously replace the EMA marker traditionally used.

Serum immunoglobulin A from patients with celiac disease inhibits human T84 intestinal crypt epithelial cell differentiation

BACKGROUND & AIMS

Celiac disease is characterized by disturbed jejunal crypt-villus axis biology with immunoglobulin (Ig) A deposits underlining the epithelium. The aim of this study was to test whether celiac disease serum IgA (reticulin/endomysial autoantibodies) interferes with the mesenchymal-epithelial cell cross-talk.

METHODS

Differentiation of T84 epithelial cells was induced with IMR-90 fibroblasts or transforming growth factor beta in three-dimensional collagen gel cultures. The effects of purified celiac IgA and monoclonal tissue transglutaminase antibodies (CUB7402) were studied by adding the antibodies to the cocultures.

RESULTS

Active celiac disease IgA, reactive for tissue transglutaminase, significantly inhibited T84 epithelial cell differentiation (P < 0.001) and increased epithelial cell proliferation (P = 0.024). Similar effects were obtained with antibodies against tissue transglutaminase.

CONCLUSIONS

Celiac disease-associated IgA class antibodies disturb transforming growth factor beta-mediated fibroblast-epithelial cell cross-talk in this in vitro crypt-villus axis model. This primary finding indicates that celiac disease-specific autoantibodies may also contribute to the formation of the gluten-triggered jejunal mucosal lesion in celiac disease.

Role of tissue transglutaminase in gliadin binding to reticular extracellular matrix and relation to coeliac disease autoantibodies

On different tissue sections, binding of gliadin to reticular matrix components was observed which was Ca2+-dependent, inhibited by Cu2+ and Zn2+ ions, by putrescine, and by preincubation with antibodies against tissue transglutaminase (tTG) suggesting that binding of gliadin is mediated by tTG. tTG was able to bind to gliadin and fibronectin fixed to microplates. Furthermore, tTG mediated binding of gliadin to fibronectin coated to microplates. On tissue sections, treatment with sera containing coeliac disease autoantibodies yielded staining patterns very similar to that of bound gliadin. Dual label experiments by means of conventional and laser scanning microscopy revealed that most of autoantibody binding sites are matched by bound gliadin. However, lack of competition between gliadin and autoantibody binding hints to ligands in very close vicinity of this enzyme. Furthermore, there were several autoantibody binding regions which did not bind gliadin. This implies the existence of further autoantigenic epitopes not related to tTG.

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

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Blockage of T-cell costimulation inhibits T-cell action in celiac disease

BACKGROUND & AIMS

Celiac disease is an exemplary model of T cell-mediated pathology. Therefore, therapeutic approaches that target T cells may successfully control this disease. CTLA-4 immunoglobulin (CTLA-4Ig) can inhibit T-cell activation by blocking the engagement of CD28. We took advantage of this tool to define the pathogenic role of gliadin-specific T cells in the induction of celiac disease.

METHODS

Duodenal biopsy specimens from 7 treated celiac patients were challenged in vitro with gliadin and CTLA-4Ig or CD40-Ig. After 24 hours, the biopsy specimens were analyzed for the presence of characteristic modifications induced by gliadin challenge.

RESULTS

CTLA-4Ig down-regulated the expression of CD25, intercellular adhesion molecule 1, interleukin 2, and interferon gamma (stained lamina propria mononuclear cells/mm2; P < 0.05) induced by gliadin challenge, caused apoptosis of gliadin-specific T cells (apoptotic T cells/mm2; P < 0.05), and inhibited the production of antiendomysial antibody (P < 0.01). However, it did not control intraepithelial T-cell migration (P = NS) and Fas expression by enterocytes. Conversely, CD40-Ig only controlled production of antiendomysial antibody.

CONCLUSIONS

In an organ culture model, CTLA-4Ig controls many but not all of the immunologic features of celiac disease.

Celiac disease: a reappraisal

During the last decade significant changes have occurred in our concepts of celiac disease. As a result of the implementation of sensitive and specific serologic tests, the epidemiology and clinical presentation of affected patients have been radically reconsidered. Extraintestinal manifestations of celiac disease have been radically reconsidered. Extraintestinal manifestations of celiac disease have been increasingly recognized, and the strict association with diseases recognized as autoimmune disorders is well established; celiac disease itself has many aspects of an autoimmune condition. Celiac disease is of interest to clinicians and scientists because it represents a valuable model for the comprehension of diseases in which environmental, genetic, and immunologic factors interplay.

Autoantibodies in celiac disease: importance of fibroblasts

BACKGROUND

Serum reticulin and endomysium autoantibodies are highly celiac disease-specific, and the autoantigens have been shown to be derived from human fibroblasts. Among human tissues, the umbilical cord also expresses these antigens. This study was conducted to compare different autoantibody tests and especially to elucidate whether human umbilical cord is a suitable substrate in tests and whether the cord jelly-derived fibroblasts express the antigens.

METHODS

The indirect immunofluorescence method was used to detect the tissue and Wharton's jelly-derived fibroblast antibodies in 334 celiac disease and control sera samples. Affinity chromatography studies were used to show the correlation between human fibroblast-derived autoantigens and tissue and gliadin antibodies. The jelly-derived fibroblasts were used as antigen in a whole-cell enzyme-linked immunosorbent assay.

RESULTS

Celiac disease patient sera showed IgA-class human umbilical cord antibody with high sensitivity (100%) and specificity (99%). All celiac disease patient sera tested showed in indirect immunofluorescence the molecules expressed by Wharton's jelly-derived fibroblasts. The whole-cell fibroblast autoantibody enzyme-linked immunosorbent assay had a sensitivity of 100% and a specificity of 81%. Human fibroblast-derived celiac disease autoantigens absorbed most of the IgA responsible for human umbilical cord antibodies but not the IgA responsible for gliadin antibodies in the same sera.

CONCLUSIONS

Wharton's jelly-derived fibroblast autoantibodies tested in a novel whole-cell enzyme-linked immunosorbent assay correlated well with the human umbilical cord but not with gliadin antibodies.

The spectrum of coeliac disease in children

Coeliac disease is the life-long intolerance to dietary gluten, usually characterized by severe damage to the small-intestinal mucosa. The widespread use of sensitive diagnostic tools, such as the serum anti-gliadin and the anti-endomysial antibodies, has shown not only that coeliac disease is one of the commonest disorders in Western countries but also that this condition is characterized by a higher degree of clinical variability than previously thought (typical, atypical and silent forms). The existence of a latent-potential coeliac disease and even a gluten-sensitive disease with immunological activation of an otherwise normal small-intestinal mucosa has recently been postulated. An increased prevalence of coeliac disease in a number of other disorders has also been reported in both children and adults. The reasons for such a wide clinical heterogeneity are still poorly understood but are likely to depend on both genetic and environmental factors. Further investigations are required to evaluate the impact of undiagnosed, clinically milder forms of coeliac disease on the well-being of the population.

Prospective significance of antiendomysium antibody positivity in subsequently verified celiac disease

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Erythema elevatum diutinum in association with coeliac disease

Erythema elevatum diutinum (EED) has been described in association with several immunological or infectious diseases. We describe a female patient who presented with clinically and histologically typical EED in whom previously undiagnosed coeliac disease was found. Appearance of EED lesions was preceded by widespread joint pains. In extensive laboratory tests, the only abnormal findings were an elevated erythrocyte sedimentation rate (ESR) and decreased haemoglobin and folic acid levels. Later, IgA and IgG type antireticulin and antigliadin antibodies were detected. Serum total IgA was elevated but no paraproteinaemia was found. In lesional skin, granular deposits of IgA and C3 were seen at the dermo-epidermal junction. A duodenal biopsy revealed total villous atrophy. Dapsone treatment was partly effective but complete healing of the EED lesions was achieved only after the introduction of a strict gluten-free diet. The patient has now remained symptom-free on the diet for 1.5 years.

Antibody pattern in childhood celiac disease

BACKGROUND

We carried out a study of the antibody pattern in 50 celiac children [34 females (F) and 16 males (M); F/M, 2.1], ages 7 months-15 years, compared with that in 25 control subjects (13 females and 12 males) of the same age.

METHODS

IgA and IgG antigliadin antibodies (AGA) were determined with an enzyme-linked immunosorbent assay technique. IgA anti-R1-reticulin antibodies (ARA) and IgA antiendomysium antibodies (EmA) were determined with the fluorescein isothiocyanate-conjugate-labeled anti-human immunoglobulin technique. To compare sensitivity and specificity, EmA were identified using monkey esophagus and human umbilical cord as substrates.

RESULTS

While AGA (IgA and IgG) showed a high sensitivity but a low specificity, ARA showed a high specificity but a low sensitivity. Data on EmA showed a high sensitivity and specificity with both tissue sections, with monkey esophagus being more sensitive (96%) and umbilical cord more specific (100%).

CONCLUSIONS

Our results confirm the importance of celiac disease-related antibodies in identifying celiac children. Moreover, the easy availability of human umbilical cord indicates that it would be proper to use this tissue as substrate, instead of monkey esophagus, for EmA search in the future.

The IgA subclass distributions of endomysium and gliadin antibodies in human sera are different

Subclass distributions of total IgA, IgA gliadin antibodies and IgA endomysium antibodies were investigated in 26 sera of patients with coeliac disease or dermatitis herpetiformis by means of enzyme immunoassay and fluorescence microscopy. Eight-point-three percent of total IgA belonged to the IgA2 subclass. The fraction of IgA2 gliadin antibodies amounted to 30.6% of IgA gliadin antibodies and was significantly different from the proportion of total IgA2. The relative percentage of IgA2 endomysium antibodies was very close to that of total IgA2 in serum (6.2%) and significantly lower than that of IgA2 gliadin antibodies. The results suggest an intestinal origin of gliadin antibodies. Different subclass distribution of IgA endomysium antibodies may be due to extraintestinal production or to the different nature of the endomysium antigen eliciting a more prominent IgA1 response than gliadin.

Production of antiendomysial antibodies after in-vitro gliadin challenge of small intestine biopsy samples from patients with coeliac disease

BACKGROUND

Diagnosis of many immune-mediated diseases is helped by detection of antibodies directed against the pathogenetic (self or foreign) antigen. In coeliac disease (CD), we have a situation in which antiendomysial antibodies (EMA), which are not specific for the pathogenetic antigen, reach a specificity and sensitivity of detection of CD approaching 100%, whereas detection of antibodies against gliadin (AGA), the pathogenetic antigen, is far less specific and sensitive in diagnosis. No direct evidence of a relation between gluten/gliadin challenge and EMA production exists. We tried to establish whether the small intestine of CD patients is the site of EMA production and whether gliadin challenge could induce their release.

METHODS

Small intestine biopsy samples from treated (23) and untreated (16) CD patients and controls (18) were cultured in vitro for 24-48 h in the presence of gliadin, another alimentary antigen, or medium. EMA and AGA were detected in the supernatants of these organ culture biopsy samples by ELISA and immunofluorescence technique, respectively.

FINDINGS

No EMA were found in the culture supernatants of biopsy samples of 18 controls, whereas they were detected in the culture supernatants of all 16 untreated CD patients irrespective of gliadin challenge. Conversely, EMA were not detected in supernatants of biopsy samples cultured in medium only from 23 treated CD patients, but were detected in 17 of the 23 biopsy samples challenged with gliadin.

INTERPRETATION

Our results suggest that a more complex pathogenetic mechanism than normally accepted is involved in CD. Furthermore, our findings raise the possibility that EMA, or the antigen recognised by them, are involved directly in the pathogenesis of CD.

The in vitro response to human fibroblast-derived extracellular matrix proteins is restricted by specific HLA class II genes. Relevance for coeliac disease

Coeliac disease is an immunologic disease of the small intestine which is caused by ingestion of wheat gliadin, the disease-promoting agent. The disease associates strongly with the particular HLA type, HLA-DQA1*0501, DQB1*0201 alleles. Further specific autoantibodies against reticulin and endomysium are found in patients; these autoantibodies appear to be disease specific. An extracellular matrix noncollagenous protein reacts specifically with CD patients' serum immunoglobulin A and is the target of antireticulin antibodies. In this study the immune response to this matrix protein was analyzed in vitro in normal, healthy individuals. Our study shows that the immune response to Fb-CDAP is strictly regulated by the HLA-DR3, DQA1*0501, DQB1*0201 alleles, and that only those cells which were positive for these alleles produced an immune response. On the other hand, half of the cells positive for these HLA alleles were responders. Monoclonal antibodies to DR and DQ inhibited the response in an additive way, showing that both DR and DQ can act as an antigen-presenting structure. The immune response to gliadin has been shown to associate with the same HLA type as CD, but the association is not as strong. Our results show that the immune responses to Fb-CDAP can be generated in vitro in genetically predisposed persons in the absence of CD.

ACP Broadsheet No 149: September 1996. Serological diagnosis of gluten sensitive enteropathy

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Gluten-sensitive enteropathy

Gluten-sensitive enteropathy is induced by dietary wheat gliadin and related proteins in genetically susceptible individuals. Most evidence suggests that the mucosal lesion represents an immunologically mediated injury triggered by gluten in the context of a particular assortment of major histocompatibility complex genes. The amino acid residues of gliadin and related proteins responsible for toxicity have not been identified; in vitro systems are available, but definitive conclusions must rely on in vivo jejunal challenges. At a conservative estimate, symptomatic gluten-sensitive enteropathy affects approximately 1 in 1000 individuals in Europe; however, it is now becoming clear that a greater proportion of individuals has clinically silent disease, and probably many others have a minor form of the the enteropathy. In most countries, the clinical presentation has changed over the past few years coming closer to the adult type of the disease, and the age of onset of symptoms is shifting upward. Liver, joint, hematologic, dental, and neurologic symptoms are increasingly being recognized. Several diseases are associated the gluten-sensitive enteropathy, such as IgA deficiency, insulin-dependent diabetes mellitus, and a range of other autoimmune diseases. Tests based on the measurement of antigliadin and antiendomysium antibodies have gained success as noninvasive screening tests; however, the ultimate diagnosis still is based on the finding of a severe histologic lesion of the jejunum while the patient is on a gluten-containing diet and on its disappearance once the gluten is excluded from the diet. A lifelong, strict GFD is mandatory for celiac children. Among other long-term problems, an increased risk of intestinal lymphoma has been reported in patients on a normal gluten-containing diet.

Antiendomysium antibodies and coeliac disease: solved and unsolved questions. An Italian multicentre study

A total of 3783 subjects were enrolled to compare IgA and IgG gliadin antibodies (AGA) with IgA endomysium antibodies (EMA) in coeliac disease (CD). Among 688 children with untreated CD EMA were positive in 93.8%, IgA AGA in 84.9% and IgG AGA in 90.2%. AGA, but not EMA, sensitivity decreased with age. EMA were present in 3.8% of control subjects, IgA AGA in 14.9% and IgG AGA in 34.3%. Follow-up of 5 of 39 EMA-positive controls showed flat mucosa. Combined determination of EMA and AGA showed an increased predictive value: if EMA and AGA were both positive, the mucosa was flat in 99.1%, if both were negative, the mucosa was normal in 99.1%. After a gluten-free diet (GFD), IgA-AGA disappeared first. Among 21 patients not on a strict GFD and in 194 coeliac patients after challenge, EMA, but not AGA, were always positive. Among 67 first-degree relatives of coeliacs, the positive predictive value of EMA was 90.6%, IgA AGA 74.3% and IgG AGA 44.6%. In conclusion, EMA screening is an excellent test for the diagnosis and follow-up of CD, and for identification of its silent and latent forms.

Specific reactivity of fluorescein isothiocyanate-conjugated separated IgG and IgA from celiac disease sera on human tissues

Study of the reaction of celiac disease-related antibodies with human substrates has been hampered by the immunological cross-reactivity between fluorescein isothiocyanate-conjugated anti-human immunoglobulins and immunoglobulins normally present in human tissues. In order to overcome this problem we extracted IgG from 2 celiac disease sera (positive for specific IgG and IgA antibodies) using a genetically engineered recombinant form of streptococcal protein G covalently immobilized on 4% agarose beads. The separated IgG and IgA was conjugated with fluorescein isothiocyanate and used in direct immunofluorescence on 0 blood group human duodenum, liver, and myocardium. Staining of the lamina propria beneath the villous epithelium, the endomysium of smooth muscle layers in the duodenum, and the liver sinusoidal and pericellular myocardial matrix was observed. The reactivity of celiac disease-related antibodies with various human tissues indicates that these antibodies are the result of a systemic immune response directed against all tissues containing matrix proteins.

The humoral immune system in coeliac disease

IgA is transported into intestinal secretions to perform exclusion of luminal antigens. The prerequisites are antigen sampling by the Peyer's patch M cells, antigen processing by antigen-presenting cells, and presentation of antigenic peptides by HLA class II molecules to immunocompetent T-cells. The basis for intestinal immunity is the maturation cycle of specifically primed T and B cells from the gut-associated lymphoid tissue via mesenteric lymph nodes and peripheral blood back to the intestinal lamina propria. In coeliac disease, patients are sensitized against gluten and serum gliadin antibodies are often detected. Gliadin antibodies are also found in other gastrointestinal diseases, other disorders and in healthy individuals not carrying the coeliac disease-specific DQA/DQB alleles. On the other hand, serum reticulin and endomysium autoantibodies are both sensitive and highly disease-specific. Positivity in patients with normal jejunal morphology indicates latency of coeliac disease. These tissue autoantibodies are directed against fibroblast-derived extracellular matrix proteins. The immune system is involved in the amplification and perpetuation of the abnormalities of the intestinal mucosa in coeliac disease. The role of antibody in the pathogenesis remains unknown. The author hypothesizes gluten-triggered autoimmune mechanism to be operative.

Partial seizures, cerebral calcifications and celiac disease

We describe the case of a 25 year old woman who has been clinically and instrumentally examined over a period of about 20 years. A diagnosis of celiac disease was made when she was four years old and, ten years later, CAT revealed the presence of bilateral cerebral calcifications. The partial occipital seizures were controlled by adopting a gluten-free diet, which is still being followed four years after the discontinuation of anti-epileptic treatment.

IgA antibodies to jejunum. Specific immunity directed against target organ of gluten-sensitive enteropathy

Serum IgA antibodies to jejunum (JAB) were found in 78 (96%) of 81 adults and children with untreated celiac disease. Not only did IgA JAB display a significant higher prevalence than IgA antigliadin antibodies (AGA) (72%) in untreated gluten-sensitive enteropathy, but they also allowed us to identify another three celiacs in addition to those detected by IgA antiendomysial antibodies (EmA). Like IgA EmA, IgA JAB persisted at low titer in seven (14%) of 50 celiacs tested after 12 months of gluten-free diet (GFD) despite the regrowth of jejunal villi, whereas IgA AGA disappeared in all these patients consistently with the normalization of intestinal mucosa. IgA JAB and EmA reappearance was close to 100% in the 13 celiacs studied after six months of gluten challenge, while IgA AGA reached the highest prevalence (about 70%) after one month of gluten ingestion without any increase in the following months. All disease and healthy controls were always negative for the three IgA antibodies. Our results prove that IgA JAB and EmA are the best screening tests for active (untreated and on gluten challenge) celiac disease, whereas IgA AGA should be used for monitoring the response to gluten withdrawal. IgA JAB are an expression of a specific immunity directed against the target organ of gluten-sensitive enteropathy, but, before ascribing them a role in the pathogenesis of celiac disease, it should be ascertained whether their production is a primary event leading to jejunal lesions or whether it is a secondary phenomenon due to antigen release from a previously damaged jejunal mucosa.

Serum IgA anti-gliadin antibodies in an adult population sample. High prevalence without celiac disease

IgA-class anti-gliadin antibodies (AGA) and IgA-, IgG-, IgM-class anti-reticulin antibodies (ARA) were determined in 1461 persons, representing 84% of a population from the village of Karksi-Nuia. AGA were detected by enzyme-linked immunosorbent assay (ELISA) and ARA by indirect immunofluorescence. Fifty-two (3.5%) persons had IgA-class AGA, of whom 48 and an additional three of four persons with diarrhea were biopsied. All biopsies showed normal small intestinal mucosal architecture. All 1461 persons were negative for ARA. Our results demonstrate that AGA are frequently detected in an adult Estonian population and positivity increases with age in persons with normal small intestinal mucosa. Positivity for AGA does not predict silent undetected celiac disease but rather represents a normal response to dietary antigens in the elderly. Inability to detect ARA suggests that celiac disease does not exist in this population. As none of the AGA-positive but ARA-negative biopsied persons had celiac disease, ARA might be a more specific serologic marker for celiac disease than AGA.

Serological markers and HLA genes among healthy first-degree relatives of patients with coeliac disease

Coeliac disease may remain undiagnosed because of the non-specific nature of the presenting symptoms. Several antibody tests are claimed as markers for this condition but a direct comparison of the available tests has not been reported. The probands and healthy first-degree relatives of 42 families with coeliac disease were studied. Histological examination of biopsy specimens revealed jejunal mucosal villous atrophy compatible with coeliac disease in 13 of 122 relatives. Reticulin-antibody-positive relatives with or without jejunal mucosal atrophy were genetically similar to the probands of the families (DR3 gene frequencies 55.3%-60.0%). Gliadin-antibody-positive relatives with normal mucosa were genetically different from the probands (DR3 gene frequency 16.7% versus 55.3%). IgA reticulin and endomysium antibodies detected 92.3% of subjects with silent coeliac disease. The only case that was missed had selective IgA deficiency and was positive for IgG-class reticulin antibodies. By contrast, gliadin antibodies detected only half of the cases. Follow-up of the 7 reticulin-antibody-positive relatives with normal mucosa revealed 2 further cases of coeliac disease and 1 of dermatitis herpetiformis during the next three years. Our family study shows that healthy reticulin-antibody-positive first-degree relatives of coeliac disease patients, irrespective of the state of the jejunal mucosa, are genetically similar to known coeliac disease patients. Reticulin-antibody positivity is an indicator of both silent and latent coeliac disease.