Early biochemical responses of the small intestine of coeliac patients to wheat gluten

Heterophilic and homophilic cadherin interactions in intestinal intermicrovillar links are species dependent

Enterocytes are specialized epithelial cells lining the luminal surface of the small intestine that build densely packed arrays of microvilli known as brush borders. These microvilli drive nutrient absorption and are arranged in a hexagonal pattern maintained by intermicrovillar links formed by 2 nonclassical members of the cadherin superfamily of calcium-dependent cell adhesion proteins: protocadherin-24 (PCDH24, also known as CDHR2) and the mucin-like protocadherin (CDHR5). The extracellular domains of these proteins are involved in heterophilic and homophilic interactions important for intermicrovillar function, yet the structural determinants of these interactions remain unresolved. Here, we present X-ray crystal structures of the PCDH24 and CDHR5 extracellular tips and analyze their species-specific features relevant for adhesive interactions. In parallel, we use binding assays to identify the PCDH24 and CDHR5 domains involved in both heterophilic and homophilic adhesion for human and mouse proteins. Our results suggest that homophilic and heterophilic interactions involving PCDH24 and CDHR5 are species dependent with unique and distinct minimal adhesive units.

Pediatric Celiac Disease Patients Show Alterations of Dendritic Cell Shape and Actin Rearrangement

Celiac disease (CD) is a frequent intestinal inflammatory disease occurring in genetically susceptible individuals upon gluten ingestion. Recent studies point to a role in CD for genes involved in cell shape, adhesion and actin rearrangements, including a Rho family regulator, Rho GTPase-activating protein 31 (ARHGAP31). In this study, we investigated the morphology and actin cytoskeletons of peripheral monocyte-derived dendritic cells (DCs) from children with CD and controls when in contact with a physiological substrate, fibronectin. DCs were generated from peripheral blood monocytes of pediatric CD patients and controls. After adhesion on fibronectin, DCs showed a higher number of protrusions and a more elongated shape in CD patients compared with controls, as assessed by immunofluorescence actin staining, transmitted light staining and video time-lapse microscopy. These alterations did not depend on active intestinal inflammation associated with gluten consumption and were specific to CD, since they were not found in subjects affected by other intestinal inflammatory conditions. The elongated morphology was not a result of differences in DC activation or maturation status, and did not depend on the human leukocyte antigen (HLA)-DQ2 haplotype. Notably, we found that ARH-GAP31 mRNA levels were decreased while RhoA-GTP activity was increased in CD DCs, pointing to an impairment of the Rho pathway in CD cells. Accordingly, Rho inhibition was able to prevent the cytoskeleton rearrangements leading to the elongated morphology of celiac DCs upon adhesion on fibronectin, confirming the role of this pathway in the observed phenotype. In conclusion, adhesion on fibronectin discriminated CD from the controls' DCs, revealing a gluten-independent CD-specific cellular phenotype related to DC shape and regulated by RhoA activity.

Intestinal Inflammation Modulates the Expression of ACE2 and TMPRSS2 and Potentially Overlaps With the Pathogenesis of SARS-CoV-2-related Disease

BACKGROUND AND AIMS

The presence of gastrointestinal symptoms and high levels of viral RNA in the stool suggest active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication within enterocytes.

METHODS

Here, in multiple, large cohorts of patients with inflammatory bowel disease (IBD), we have studied the intersections between Coronavirus Disease 2019 (COVID-19), intestinal inflammation, and IBD treatment.

RESULTS

A striking expression of ACE2 on the small bowel enterocyte brush border supports intestinal infectivity by SARS-CoV-2. Commonly used IBD medications, both biologic and nonbiologic, do not significantly impact ACE2 and TMPRSS2 receptor expression in the uninflamed intestines. In addition, we have defined molecular responses to COVID-19 infection that are also enriched in IBD, pointing to shared molecular networks between COVID-19 and IBD.

CONCLUSIONS

These data generate a novel appreciation of the confluence of COVID-19- and IBD-associated inflammation and provide mechanistic insights supporting further investigation of specific IBD drugs in the treatment of COVID-19. Preprint doi: https://doi.org/10.1101/2020.05.21.109124.

Autoantibodies in the Extraintestinal Manifestations of Celiac Disease

Increased antibody reactivity towards self-antigens is often indicative of a disruption of homeostatic immune pathways in the body. In celiac disease, an autoimmune enteropathy triggered by the ingestion of gluten from wheat and related cereals in genetically predisposed individuals, autoantibody reactivity to transglutaminase 2 is reflective of the pathogenic role of the enzyme in driving the associated inflammatory immune response. Autoantibody reactivity to transglutaminase 2 closely corresponds with the gluten intake and clinical presentation in affected patients, serving as a highly useful biomarker in the diagnosis of celiac disease. In addition to gastrointestinal symptoms, celiac disease is associated with a number of extraintestinal manifestations, including those affecting skin, bones, and the nervous system. Investigations of these manifestations in celiac disease have identified a number of associated immune abnormalities, including B cell reactivity towards various autoantigens, such as transglutaminase 3, transglutaminase 6, synapsin I, gangliosides, and collagen. Clinical relevance, pathogenic potential, mechanism of development, and diagnostic and prognostic value of the various identified autoantibody reactivities continue to be subjects of investigation and will be reviewed here.

Serum I-FABP Detects Gluten Responsiveness in Adult Celiac Disease Patients on a Short-Term Gluten Challenge

OBJECTIVES

Response to gluten challenge (GC) is a key feature in diagnostic algorithms and research trials in celiac disease (CD). Currently, autoantibody titers, late responders to GC, and invasive duodenal biopsies are used to evaluate gluten responsiveness. This study investigated the accuracy of serum intestinal-fatty acid binding protein (I-FABP), a marker for intestinal epithelial damage, to predict intestinal damage during GC in patients with CD.

METHODS

Twenty adult CD patients in remission underwent a two-week GC with 3 or 7.5 g of gluten daily. Study visits occurred at day -14, 0, 3, 7, 14, and 28. Serum I-FABP, antibodies to tissue transglutaminase (tTG-IgA), deamidated gliadin peptides (IgA-DGP), and anti-actin (AAA-IgA) were assessed at each visit. Villous-height to crypt-depth ratio (Vh:Cd) and intraepithelial lymphocyte (IEL) count were evaluated at day -14, 3, and 14. Forty-three CD-serology negative individuals were included to compare serum I-FABP levels in CD patients on a gluten-free diet (GFD) with those in healthy subjects.

RESULTS

Serum I-FABP levels increased significantly during a two-week GC. In contrast, the most pronounced autoantibody increase was found at day 28, when patients had already returned to a GFD for two weeks. IgA-AAA titers were only significantly elevated at day 28. I-FABP levels and IEL count correlated at baseline (r=0.458, P=0.042) and at day 14 (r=0.654, P=0.002) of GC. Neither gluten dose nor time on a GFD influenced I-FABP change during GC.

CONCLUSIONS

Serum I-FABP levels increased significantly during a two-week GC in adult CD patients and correlated with IEL count. The data suggest that serum I-FABP is an early marker of gluten-induced enteropathy in celiac patients and may be of use in both clinical and research settings.

PeakForce Tapping resolves individual microvilli on living cells

Microvilli are a common structure found on epithelial cells that increase the apical surface thus enhancing the transmembrane transport capacity and also serve as one of the cell's mechanosensors. These structures are composed of microfilaments and cytoplasm, covered by plasma membrane. Epithelial cell function is usually coupled to the density of microvilli and its individual size illustrated by diseases, in which microvilli degradation causes malabsorption and diarrhea. Atomic force microscopy (AFM) has been widely used to study the topography and morphology of living cells. Visualizing soft and flexible structures such as microvilli on the apical surface of a live cell has been very challenging because the native microvilli structures are displaced and deformed by the interaction with the probe. PeakForce Tapping® is an AFM imaging mode, which allows reducing tip-sample interactions in time (microseconds) and controlling force in the low pico-Newton range. Data acquisition of this mode was optimized by using a newly developed PeakForce QNM-Live Cell probe, having a short cantilever with a 17-µm-long tip that minimizes hydrodynamic effects between the cantilever and the sample surface. In this paper, we have demonstrated for the first time the visualization of the microvilli on living kidney cells with AFM using PeakForce Tapping. The structures observed display a force dependence representing either the whole microvilli or just the tips of the microvilli layer. Together, PeakForce Tapping allows force control in the low pico-Newton range and enables the visualization of very soft and flexible structures on living cells under physiological conditions.

Protein-protein interaction network of celiac disease

AIM

The aim of this study is to investigate the Protein-Protein Interaction Network of Celiac Disease.

BACKGROUND

Celiac disease (CD) is an autoimmune disease with susceptibility of individuals to gluten of wheat, rye and barley. Understanding the molecular mechanisms and involved pathway may lead to the development of drug target discovery. The protein interaction network is one of the supportive fields to discover the pathogenesis biomarkers for celiac disease.

MATERIAL AND METHODS

In the present study, we collected the articles that focused on the proteomic data in celiac disease. According to the gene expression investigations of these articles, 31 candidate proteins were selected for this study. The networks of related differentially expressed protein were explored using Cytoscape 3.3 and the PPI analysis methods such as MCODE and ClueGO.

RESULTS

According to the network analysis Ubiquitin C, Heat shock protein 90kDa alpha (cytosolic and Grp94); class A, B and 1 member, Heat shock 70kDa protein, and protein 5 (glucose-regulated protein, 78kDa), T-complex, Chaperon in containing TCP1; subunit 7 (beta) and subunit 4 (delta) and subunit 2 (beta), have been introduced as hub-bottlnecks proteins. HSP90AA1, MKKS, EZR, HSPA14, APOB and CAD have been determined as seed proteins.

CONCLUSION

Chaperons have a bold presentation in curtail area in network therefore these key proteins beside the other hub-bottlneck proteins may be a suitable candidates biomarker panel for diagnosis, prognosis and treatment processes in celiac disease.

Overexpression of Hsp70 confers cytoprotection during gliadin exposure in Caco-2 cells

BACKGROUND

In Celiac disease (CD), cytoskeletal integrity of intestinal cells is disrupted by gliadin exposure. This study investigates the role of heat shock protein (Hsp)70 during cytoskeletal recovery in CD by assessing its induction and effects on junctional proteins.

METHODS

Using an in-vitro model of CD, cytoskeletal injury and recovery was assessed in gliadin-exposed Caco-2 cells by measuring cellular distribution of ezrin, E-cadherin, and Hsp70 by differential centrifugation. Effects of Hsp70 were tested by an in-vitro repair assay, based on the incubation of injured or recovered cytoskeletal cellular fractions in noncytoskeletal supernatants containing low or high levels of Hsp70, or by transient transfection of Caco-2 cells with Hsp70.

RESULTS

Cytoskeletal disruption of ezrin and E-cadherin was demonstrated in gliadin-exposed Caco-2 cells by their significant shift from the cytoskeletal pellet into the noncytoskeletal supernatant fraction. Recovery from gliadin exposure was associated with induction and cytoskeletal redistribution of Hsp70. The in-vitro repair assay delineated direct evidence for HSP-mediated repair by stabilization of junctional proteins by Hsp70. Overexpression of Hsp70 resulted in significantly increased cytoskeletal integrity.

CONCLUSION

Our results establish an essential role of HSP-mediated cytoskeletal repair in Caco-2 cells during recovery from in-vitro gliadin exposure.

Shaping the intestinal brush border

Epithelial cells from diverse tissues, including the enterocytes that line the intestinal tract, remodel their apical surface during differentiation to form a brush border: an array of actin-supported membrane protrusions known as microvilli that increases the functional capacity of the tissue. Although our understanding of how epithelial cells assemble, stabilize, and organize apical microvilli is still developing, investigations of the biochemical and physical underpinnings of these processes suggest that cells coordinate cytoskeletal remodeling, membrane-cytoskeleton cross-linking, and extracellular adhesion to shape the apical brush border domain.

Intestinal brush border assembly driven by protocadherin-based intermicrovillar adhesion

Transporting epithelial cells build apical microvilli to increase membrane surface area and enhance absorptive capacity. The intestinal brush border provides an elaborate example with tightly packed microvilli that function in nutrient absorption and host defense. Although the brush border is essential for physiological homeostasis, its assembly is poorly understood. We found that brush border assembly is driven by the formation of Ca(2+)-dependent adhesion links between adjacent microvilli. Intermicrovillar links are composed of protocadherin-24 and mucin-like protocadherin, which target to microvillar tips and interact to form a trans-heterophilic complex. The cytoplasmic domains of microvillar protocadherins interact with the scaffolding protein, harmonin, and myosin-7b, which promote localization to microvillar tips. Finally, a mouse model of Usher syndrome lacking harmonin exhibits microvillar protocadherin mislocalization and severe defects in brush border morphology. These data reveal an adhesion-based mechanism for brush border assembly and illuminate the basis of intestinal pathology in patients with Usher syndrome. PAPERFLICK:

A celiac cellular phenotype, with altered LPP sub-cellular distribution, is inducible in controls by the toxic gliadin peptide P31-43

Celiac disease (CD) is a frequent inflammatory intestinal disease, with a genetic background, caused by gliadin-containing food. Undigested gliadin peptides P31-43 and P57-68 induce innate and adaptive T cell-mediated immune responses, respectively. Alterations in the cell shape and actin cytoskeleton are present in celiac enterocytes, and gliadin peptides induce actin rearrangements in both the CD mucosa and cell lines. Cell shape is maintained by the actin cytoskeleton and focal adhesions, sites of membrane attachment to the extracellular matrix. The locus of the human Lipoma Preferred Partner (LPP) gene was identified as strongly associated with CD using genome-wide association studies (GWAS). The LPP protein plays an important role in focal adhesion architecture and acts as a transcription factor in the nucleus. In this study, we examined the hypothesis that a constitutive alteration of the cell shape and the cytoskeleton, involving LPP, occurs in a cell compartment far from the main inflammation site in CD fibroblasts from skin explants. We analyzed the cell shape, actin organization, focal adhesion number, focal adhesion proteins, LPP sub-cellular distribution and adhesion to fibronectin of fibroblasts obtained from CD patients on a Gluten-Free Diet (GFD) and controls, without and with treatment with A-gliadin peptide P31-43. We observed a “CD cellular phenotype” in these fibroblasts, characterized by an altered cell shape and actin organization, increased number of focal adhesions, and altered intracellular LPP protein distribution. The treatment of controls fibroblasts with gliadin peptide P31-43 mimics the CD cellular phenotype regarding the cell shape, adhesion capacity, focal adhesion number and LPP sub-cellular distribution, suggesting a close association between these alterations and CD pathogenesis.

Detection of autoantibodies against actin filaments in celiac disease

INTRODUCTION

Serum autoantibodies specifically directed toward intracellular cytoskeletal actin filaments (anti-actin antibodies, AAA) were found to be associated with intestinal villous atrophy (IVA) in celiac disease (CD). The aim of this study was to assess IgA-AAA with a commercial test that uses sections of rat intestinal epithelial cells in a well-selected cohort of patients and to evaluate the relationship between the presence of serum IgA-AAA and the severity of intestinal mucosa damage.

MATERIALS AND METHODS

Serum samples from 70 CD patients and 150 controls subjects were analyzed retrospectively for the presence of IgA-AAA.

RESULTS

The indirect immunofluorescence test that we used has a specificity of 100%; the sensitivity of the test is not high (25.7%). In this study we also show that serum AAA are more frequently positive in CD patients with total IVA (77.8%) and that this association is significant

DISCUSSION

IgA-AAA certainly cannot take the place of much more sensitive tests such as a-tTG and EMA in the diagnosis of CD because of their low sensitivity; nonetheless, these antibodies could be determined in a-tTG and/or EMA positive patients who cannot undergo an intestinal biopsy because of a severe contraindication, or in the case of negative consensus regarding endoscopy, or when the histology interpretation is difficult.

CONCLUSION

In conclusion, the IFI commercial test with intestinal epithelial cells as substrate offers a useful method for IgA-AAA determination. Serum IgA-AAA positivity is indicative of more severe intestinal histology damage and their assay could be a real help to the clinician, especially in the complicated cases.

Impairment of protein trafficking by direct interaction of gliadin peptides with actin

Intestinal celiac disease (CD) is triggered by peptic-tryptic digest of gluten, known as Frazer's Fraction (FF), in genetically predisposed individuals. Here, we investigate the immediate effects of FF on the actin cytoskeleton and the subsequent trafficking of actin-dependent and actin-independent proteins in COS-1 cells. Morphological alterations in the actin filaments were revealed concomitant with a drastic reduction in immunoprecipitated actin from cells incubated with FF. These alterations elicit impaired protein trafficking of intestinal sucrase-isomaltase, a glycoprotein that follows an actin-dependent vesicular transport to the cell surface. However, the actin-independent transport of intestinal lactase phlorizin hydrolase remains unaffected. Moreover, the morphological alteration in actin is induced by direct interaction of this protein with gliadin peptides carrying the QQQPFP epitope revealed by co-immunoprecipitation utilizing a monoclonal anti-gliadin antibody. Finally, stimulation of cells with FF directly influences the binding of actin to Arp2. Altogether, our data demonstrate that FF directly interacts with actin and alters the integrity of the actin cytoskeleton thus leading to an impaired trafficking of intestinal proteins that depend on an intact actin network. This direct interaction could be related to the endocytic segregation of gliadin peptides as well as the delayed endocytic vesicle trafficking and maturation in gliadin-positive intestinal epithelial cells and opens new insights into the pathogenesis of CD.

The enterocyte microvillus is a vesicle-generating organelle

For decades, enterocyte brush border microvilli have been viewed as passive cytoskeletal scaffolds that serve to increase apical membrane surface area. However, recent studies revealed that in the in vitro context of isolated brush borders, myosin-1a (myo1a) powers the sliding of microvillar membrane along core actin bundles. This activity also leads to the shedding of small vesicles from microvillar tips, suggesting that microvilli may function as vesicle-generating organelles in vivo. In this study, we present data in support of this hypothesis, showing that enterocyte microvilli release unilamellar vesicles into the intestinal lumen; these vesicles retain the right side out orientation of microvillar membrane, contain catalytically active brush border enzymes, and are specifically enriched in intestinal alkaline phosphatase. Moreover, myo1a knockout mice demonstrate striking perturbations in vesicle production, clearly implicating this motor in the in vivo regulation of this novel activity. In combination, these data show that microvilli function as vesicle-generating organelles, which enable enterocytes to deploy catalytic activities into the intestinal lumen.

The use of Cellomics to study enterocyte cytoskeletal proteins in coeliac disease patients

Coeliac disease is characterised by inflammation of small intestinal mucosa accompanied by abnormal villous architecture. It is now accepted that some patients with positive coeliac serology tests may have minor mucosal lesions that may not be apparent on routine histopathological analysis. The aim of the study was to perform detailed examination of enterocyte morphology and cytoskeletal structures using a high content analysis technology. Duodenal biopsies from 14 untreated and 10 treated coeliac patients and from 20 non-coeliac controls were examined. Tissue sections from six patients (study group subjects) before and after the development of gluten-sensitive enteropathy were also investigated. Immunohistochemical studies were performed on paraffin-embedded sections using an anti-α-tubulin antibody. Significant differences in enterocyte morphology and intracellular cytoskeletal structures were demonstrated in patients with proven coeliac disease and in the study group subjects. These changes were present in study group biopsies before evidence of enteropathy, as assessed by routine microscopy. This is the first study to demonstrate detailed characteristics of enterocyte morphology in coeliac patients using a high content analysis approach. The use of this technology allows a quantitative analysis of enterocyte intracellular structures from routine biopsy material and permits detection of subtle changes that precede the characteristic histological lesion.

Autoantibodies in celiac disease

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

Anti-actin IgA antibodies in severe coeliac disease

Anti-actin IgA antibodies have been found in sera of coeliacs. Our aim was to define the prevalence and clinical significance of anti-actin IgA in coeliacs before and after gluten withdrawal. One hundred and two biopsy-proven coeliacs, 95 disease controls and 50 blood donors were studied. Anti-actin IgA were evaluated by different methods: (a) antimicrofilament positivity on HEp-2 cells and on cultured fibroblasts by immunofluorescence; (b) anti-actin positivity by enzyme-linked immuosorbent assay (ELISA); and (c) presence of the tubular/glomerular pattern of anti-smooth muscle antibodies on rat kidney sections by immunofluorescence. Antimicrofilament IgA were present in 27% of coeliacs and in none of the controls. Antimicrofilament antibodies were found in 25 of 54 (46%) coeliacs with severe villous atrophy and in three of 48 (6%) with mild damage (P < 0.0001). In the 20 patients tested, antimicrofilaments IgA disappeared after gluten withdrawal in accordance with histological recovery. Our study shows a significant correlation between antimicrofilament IgA and the severity of intestinal damage in untreated coeliacs. The disappearance of antimicrofilament IgA after gluten withdrawal predicts the normalization of intestinal mucosa and could be considered a useful tool in the follow-up of severe coeliac disease.

Enterocyte actin autoantibody detection: a new diagnostic tool in celiac disease diagnosis: results of a multicenter study

OBJECTIVES

This study describes a new method to detect autoantibodies against actin filaments (AAA) as a serological marker of intestinal villous atrophy (IVA) in celiac disease (CD), and reports the results of an Italian double-blind multicenter study.

METHODS

IgA-AAA were analyzed by immunofluorescence using a newly developed method based on intestinal epithelial cells cultured in presence of colchicine. IgA-AAA were blindly evaluated prospectively in 223 antiendomysial antibody (AEA) and/or antitransglutaminase antibody (TGA) positive subjects and in 78 AEA and TGA negative subjects. IgA-AAA positive patients underwent an intestinal biopsy to confirm the diagnosis. Moreover, IgA-AAA were retrospectively investigated in 84 biopsy-proven CD patients and in 2,000 new consecutively collected serum samples from AEA and TGA negative nonbiopsied subjects.

RESULTS

IgA-AAA were positive in 98.2% of the CD patients with flat mucosa, in 89% with subtotal villous atrophy, and in 30% with partial villous atrophy. IgA-AAA were present in none of the AEA and TGA negative nonbiopsied controls. In AEA and/or TGA positive CD patients IgA-AAA positivity significantly correlated with IVA (p < 0.000 in the prospective study, p = 0.005 in the retrospective study). In the prospective study, the values of sensitivity, specificity, the positive predictive value, the negative predictive value, and the efficiency of the IgA-AAA test to identify patients with IVA were, respectively, 83.9%, 95.1%, 97.8%, 69.2%, and 87.0%. Furthermore, a significant correlation (p < 0.0001) was found between the IgA-AAA serum titre and the degree of IVA (rs 0.56).

CONCLUSIONS

The results of this multicenter study show that the new method for IgA-AAA detection could represent a practical diagnostic tool in AEA and/or TGA positive subjects, which would be especially useful when IVA shows a patchy distribution, when the histological picture is difficult to interpret, or when a biopsy could represent a life-threatening risk.

Transition of care between paediatric and adult gastroenterology. Coeliac disease

Coeliac disease is a condition in which there is an abnormal mucosa in the small intestine. It improves with a gluten free diet, with avoidance of wheat, rye, barley and possibly oats. The history and epidemiology of this condition are discussed. Diagnosis is based on demonstrating that the characteristic histological abnormalities in the small intestine are dependent on gluten ingestion. Diagnostic pitfalls are discussed. The anti-endomysium and anti-tissue transglutaminase antibodies are specific and sensitive diagnostic tools. The wide variety of clinical symptoms and presentations are discussed including the associated condition of dermatitis herpetiformis. Failure to respond to a gluten-free diet can represent simple dietary problems, an alternative diagnosis or, occasionally, the development of a serious complication of coeliac disease such as ulcerative jejunitis or enteropathy-associated T cell lymphoma. Progress towards the characterization of the toxic epitopes within gluten that exacerbate coeliac disease and our current understanding of the genetics of the disorder are presented.

Immune reaction against the cytoskeleton in coeliac disease

BACKGROUND

The cytoskeleton actin network of intestinal microvilli has been found to be rapidly impaired after gluten challenge in coeliac disease (CD). The aim of this study was to investigate the presence of an immune reaction towards cytoskeleton structures such as actin filaments in CD.

METHODS

Eighty three antiendomysial antibody positive CD patients (52 children and 31 adults) were studied at our outpatient clinics from 1996 to 1998 using indirect immunofluorescence, ELISA, and western blotting for antiactin (AAA) and antitissue transglutaminase (TGA) antibodies before and after a gluten free diet (GFD). Sixteen patients with smooth muscle antibody positive autoimmune hepatitis, 21 with inflammatory bowel diseases, seven with small bowel bacterial overgrowth, and 60 healthy subjects were studied as controls.

RESULTS

Fifty nine of 83 CD patients (28/31 adults (90.3%); 31/52 children (59.6%)) were positive for IgA and/or IgG AAA. Seventy seven (92.7%) were positive for IgA TGA. IgA AAA were strongly correlated with more severe degrees of intestinal villous atrophy (p<0.0001; relative risk 86.17). After a GFD, AAA became undetectable within five months.

CONCLUSIONS

Apart from the immune reaction against the extracellular matrix, we have described an immune reaction against the cytoskeleton in both children and adults with CD. As AAA are strongly associated with more severe degrees of villous atrophy, they may represent a useful serological marker of severe intestinal atrophy in CD.

Estimation of serum beta-2-microglobulin in children with malabsorption disorders syndrome

The aim of this study was to examine serum levels of beta-2-microglobulin (b-2-m) in 132 children at various stages for the evaluation of celiac disease (CD). Serum b-2-m was analyzed by a radio immunoassay (RIA) method, using a beta-2-micro RIA kit (Pharmacia, Uppsala, Sweden). The mean concentration of b-2-m in children with an established diagnosis of CD was 4.38 +/- 1.86 mg/l. In children receiving a gluten-free diet, the mean b-2-m concentration was 1.95 +/- 1.09 mg/l, and in children who received a gluten-containing diet, the concentration was 3.19 +/- 0.71 mg/l. In children with CD who were on a gluten-free diet and who presented no antibodies against EmA in class IgA serum, b-2-m concentration was within the normal range (1.86 +/- 0.55 mg/l). The concentration of b-2-m in children with secondary malabsorption syndrome was within the physiological range (1.77 +/- 0.64 mg/l). In children with IgA-EmA antibodies present in serum, the b-2-m concentration was significantly higher (3.5 +/- 1.23 mg/l; P < 0.001) than that in children with IgA-EmA in serum. We showed a linear dependence between the degree of villous atrophy in CD and concentrations of b-2-m in serum (r2 = 0.94). Determination of b-2-m concentration in sera of children with CD may be used to monitor treatment with a gluten-free diet and to differentiate secondary malabsorption syndrome from CD.

Differential upregulation of intercellular adhesion molecule-1 in coeliac disease

The expression of intercellular adhesion molecule-1 (ICAM-1) was studied on peroral jejunal biopsies from patients with coeliac disease. The biopsies from untreated patients exhibited greater staining of the superficial lamina propria cells compared with treated patients and controls. A gluten challenge in treated patients produced an altered staining pattern within 2 h. The results demonstrate the role of ICAM-1 expression in coeliac disease, providing further evidence for the role of lamina propria cells in the pathogenesis of this condition.