Inhibition of Transglutaminase 2 as a Therapeutic Strategy in Celiac Disease-In Vitro Studies in Intestinal Cells and Duodenal Biopsies.

Enzymatic modification of gliadin peptides by human transglutaminase 2 (TG2) is a key mechanism in the pathogenesis of celiac disease (CD) and represents a potential therapeutic target. Recently, we have identified the small oxidative molecule PX-12 as an effective inhibitor of TG2 in vitro. In this study, we further investigated the effect of PX-12 and the established active-site directed inhibitor ERW1041 on TG2 activity and epithelial transport of gliadin peptides. We analyzed TG2 activity using immobilized TG2, Caco-2 cell lysates, confluent Caco-2 cell monolayers and duodenal biopsies from CD patients. TG2-mediated cross-linking of pepsin-/trypsin-digested gliadin (PTG) and 5BP (5-biotinamidopentylamine) was quantified by colorimetry, fluorometry and confocal microscopy. Cell viability was tested with a resazurin-based fluorometric assay. Epithelial transport of promofluor-conjugated gliadin peptides P31-43 and P56-88 was analyzed by fluorometry and confocal microscopy. PX-12 reduced TG2-mediated cross-linking of PTG and was significantly more effective than ERW1041 (10 µM, 15 ± 3 vs. 48 ± 8%, p < 0.001). In addition, PX-12 inhibited TG2 in cell lysates obtained from Caco-2 cells more than ERW1041 (10 µM; 12 ± 7% vs. 45 ± 19%, p < 0.05). Both substances inhibited TG2 comparably in the intestinal lamina propria of duodenal biopsies (100 µM, 25 ± 13% vs. 22 ± 11%). However, PX-12 did not inhibit TG2 in confluent Caco-2 cells, whereas ERW1041 showed a dose-dependent effect. Similarly, epithelial transport of P56-88 was inhibited by ERW1041, but not by PX-12. Cell viability was not negatively affected by either substance at concentrations up to 100 µM. PX-12 did not reduce TG2 activity or gliadin peptide transport in confluent Caco-2 cells. This could be caused by rapid inactivation or degradation of the substance in the Caco-2 cell culture. Still, our in vitro data underline the potential of the oxidative inhibition of TG2. The fact that the TG2-specific inhibitor ERW1041 reduced the epithelial uptake of P56-88 in Caco-2 cells further strengthens the therapeutic potential of TG2 inhibitors in CD.

Constitutive Differential Features of Type 2 Transglutaminase in Cells Derived from Celiac Patients and from Healthy Subjects.

Type 2 transglutaminase (TG2) is a ubiquitous enzyme able to modify gliadin peptides introduced into the organism through the diet. By means of its catalytic activity, TG2 seems to have an important pathogenetic role in celiac disease (CD), an inflammatory intestinal disease caused by the ingestion of gluten-containing cereals. A strong autoimmune response to TG2 characterizes CD development. Anti-TG2 antibodies specifically derange the uptake of the α-gliadin peptide 31-43 by control, but not by celiac dermal fibroblasts, underlying some different constitutive features regarding TG2 in healthy and celiac subjects. Our aim was to investigate whether these differences depended on a different TG2 subcellular distribution and whether peptide 31-43 differentially regulated TG2 expression and activity in cells of the two groups of subjects. We found that TG2 was more abundantly associated with membranes of celiac fibroblasts than of control cells, in particular with the early endosomal and autophagic compartments. We also found that peptide 31-43 differentially affected TG2 expression and activity in the two groups of cells, activating TG2 more in control than in celiac cells and inducing TG2 expression in celiac cells, but not in control ones. The different TG2 subcellular localization and the different way the peptide 31-43 modulates TG2 activity and availability into control and CD cells suggested that TG2 is involved in the definition of a constitutive CD cellular phenotype, thus having an important and still undefined role in CD pathogenesis.

HLA-DQ2 homozygosis increases tTGA levels at diagnosis but does not influence the clinical phenotype of coeliac disease: A multicentre study.

BACKGROUND AND PURPOSE: Magnitude of gluten-specific T-cell responses in coeliac disease (CD) might be dependent on HLA-DQ2 gene dose. We aimed to investigate the effects of HLA-DQB1*02 allele dose on clinical outcomes. METHODS: We reviewed the charts of all coeliac patients attending to three Hungarian university clinics after 1997 and included those patients, who (a) were diagnosed with CD, (b) underwent high-resolution HLA typing and (c) were ≥18 years at the time of data collection. HLA typing was performed to determine DQB1*02 allele dose. Patients were divided into risk groups by DQB1*02 allele dose, as follows: high-, intermediate- and low-risk groups corresponded to a double, single and zero doses, respectively. We used ANOVA and Pearson's chi-squared test to explore association between HLA risk and clinical variables. RESULTS: A total of 727 coeliac patients attended the clinics but only 105 (14.4%) patients were eligible for inclusion. High, intermediate and low HLA risk patients comprised 35.3%, 52.3% and 12.3% of the study population, respectively. Double dose of HLA-DQB1*02 was more frequent in patient with high tTGA level (>10 times the upper limit of normal; p = 0.045). Gene dose was not associated with younger age at diagnosis (p = 0.549), gender (p = 0.739), more severe diagnostic histology (p = 0.318), more frequent classical presentation (p = 0.846), anaemia (p = 0.611), metabolic bone disease (p = 0.374), dermatitis herpetiformis (p = 0.381) and autoimmune diseases (p = 0.837). CONCLUSIONS: Our study shows a significant gene dose effect in terms of tTGA level at diagnosis, but no significant association between HLA-DQB1*02 allele dose and the clinical outcomes in CD.

Ex vivo Culture of Duodenal Biopsies from Patients with Dermatitis Herpetiformis Indicates that Transglutaminase 3 Antibody Production Occurs in the Gut.

Coeliac disease and dermatitis herpetiformis (DH) are characterized by autoantibodies targeting transglutaminase (TG)2 and TG3, respectively. Previous studies show that TG2 antibodies are produced in the gut and can be assessed in organ culture of small-intestinal biopsies from patients with coeliac disease. Thus far, no studies have investigated TG3 antibodies in organ culture of biopsies from patients with DH, or exploited the method in DH. The aim of this study was to investigate TG3 and TG2 antibody responses in serum and small-intestinal biopsies from patients with DH with active disease, and from those in remission. The majority of patients with DH were negative for both serum and organ culture medium TG2-targeting antibodies. Surprisingly, patients with active DH secreted TG3 antibodies into the culture medium despite seronegativity. In patients secreting high levels of TG3 antibodies into the culture medium, we also detected TG3-antibody-positive cells in the small-intestinal mucosa. These findings suggest that TG3 antibodies can be investigated in the organ culture system and that their secretion occurs in the small intestine, especially in active DH.

Understanding the Catalytic Mechanism and the Substrate Specificity of an Engineered Gluten Hydrolase by QM/MM Molecular Dynamics and Free Energy Simulations.

Celiac sprue, also known as gluten-sensitive enteropathy, is a chronic disease suffered by approximately 1% of the world's population. Engineered enzymes have been emerging to treat celiac disease by hydrolyzing the pathogenic peptides of gluten. For example, Kuma010 has been studied experimentally and proved to be a promising gluten hydrolase under gastric conditions. However, the detailed catalytic mechanism and the substrate specificity are still unclear. In this paper, quantum-mechanical/molecular-mechanical (QM/MM) molecular dynamics (MD) and free energy simulations were performed to determine the catalytic mechanism, the substrate specificity, and the role of the active-site residues during the reaction. The results given here demonstrate that the Kuma010 has a similar catalytic mechanism but different substrate specificity as wild-type kumamolisin-As. Binding properties of the enzyme (especially mutated residues) and substrate complex are discussed, and activation free energy barriers toward different substrates have also been examined. The computational free energy results are in reasonable agreement with the experimental data. The strategy for developing next-generation gluten hydrolases is discussed.

Screening for celiac disease, by endomysial antibodies, in patients with unexplained hypertransaminasaemia.

OBJECTIVE: To do a serological screening for celiac disease in patients with unexplained liver cytolysis. MATERIALS AND METHODS: Fifty-six patients with liver cytolysis without known aetiology were studied. Endomysial antibodies were determined by indirect immunofluorescence on human umbilical cord. Two thousand and five hundred blood donors served as control group. For statistical analysis, we used Chi-square or Fisher's exact test. RESULTS: The frequency of IgA endomysial antibodies in our patients was significantly higher than in the control group (8.92% vs. 0.28%, p < .001). In female, endomysial antibodies were significantly more frequent in patients than in healthy subjects (12.12% vs. 0.4%; p < .001). In male, endomysial antibodies were significantly more frequent in patients than in healthy subjects (4.34% vs. 0.22%; p = .006). The frequency of positive EMA in female patients was higher than in male, but the difference was not statistically significant (12.12% vs. 4.43%; p = .6). Two patients were non-compliant with the gluten-free diet. One patient was out of touch. For the two other patients, transaminase levels reverted to normal level within six months of strict gluten withdrawal. CONCLUSIONS: A screening for celiac disease should be included within the diagnosis protocol of liver cytolysis.

Association of PTPN22 Single Nucleotide Polymorphisms with Celiac Disease.

OBJECTIVES: Celiac disease is a chronic autoimmune disease in which gene-environment interactions cause the immune system to unfavorably react to naturally gluten-containing foods. PTPN22 plays a crucial role in regulating the function of various cells of the immune system, particularly T cells. Polymorphisms of the PTPN22 gene have been associated with many autoimmune diseases. The present genetic association study was conducted to investigate the possible associations between PTPNTT single nucleotide polymorphisms (SNPs) and celiac disease in an Iranian population. MATERIALS AND METHODS: The study population consisted of 45 patients with celiac disease and 93 healthy controls. The study genotyped five SNPs of the PTPN22 gene: rs12760457, rs1310182, rs1217414, rs33996649, and rs2476601. RESULTS AND CONCLUSIONS: Control and patient groups did not differ on the genotype distribution of four of five investigated SNPs in the PTPN22 gene, for example, rs12760457, rs2476601, rs1217414, and rs33996649. The only investigated PTPN22 variant, which could be associated with CD, was rs1310182. A significant increase in the carriage of the T allele of rs1310182 in CD patients was observed (OR (95% CI) = 11.42 (5.41, 24.1), p value < 0.0001). The TT genotype of this SNP was significantly associated with celiac disease. Our study suggests that the rs1310182 SNP of PTPN22 gene may be a predisposing factor of celiac disease in the Iranian population. Further studies are required to investigate the issue in other racial and ethnic subgroups.

Structural Basis for Antigen Recognition by Transglutaminase 2-specific Autoantibodies in Celiac Disease.

Antibodies to the autoantigen transglutaminase 2 (TG2) are a hallmark of celiac disease. We have studied the interaction between TG2 and an anti-TG2 antibody (679-14-E06) derived from a single gut IgA plasma cell of a celiac disease patient. The antibody recognizes one of four identified epitopes targeted by antibodies of plasma cells of the disease lesion. The binding interface was identified by small angle x-ray scattering, ab initio and rigid body modeling using the known crystal structure of TG2 and the crystal structure of the antibody Fab fragment, which was solved at 2.4 Å resolution. The result was confirmed by testing binding of the antibody to TG2 mutants by ELISA and surface plasmon resonance. TG2 residues Arg-116 and His-134 were identified to be critical for binding of 679-14-E06 as well as other epitope 1 antibodies. In contrast, antibodies directed toward the two other main epitopes (epitopes 2 and 3) were not affected by these mutations. Molecular dynamics simulations suggest interactions of 679-14-E06 with the N-terminal domain of TG2 via the CDR2 and CDR3 loops of the heavy chain and the CDR2 loop of the light chain. In addition there were contacts of the framework 3 region of the heavy chain with the catalytic domain of TG2. The results provide an explanation for the biased usage of certain heavy and light chain gene segments by epitope 1-specific antibodies in celiac disease.

Herpesvirus Infections and Transglutaminase Type 2 Antibody Positivity in Childhood: The Generation R Study.

OBJECTIVES: Persistent viral infections have been implicated in the etiology of autoimmune diseases in adulthood, but it is not known whether herpesviruses are associated with the development of celiac disease autoimmunity in childhood. We assessed whether herpesvirus infections are associated with transglutaminase type 2 antibody (TG2A) concentrations in children at 6 years of age. METHODS: The present study was embedded within a population-based prospective cohort study. Serum immunoglobulin G levels against Epstein-Barr virus, cytomegalovirus (CMV), and herpes simplex virus type 1 were measured by enzyme-linked immunosorbent assay , and TG2A concentrations with fluorescence enzyme immunoassay in 4420 children at 6 years of age. Children were categorized based on TG2A concentrations into negative (<7 U/mL), positive (≥7-70 U/mL), and strongly positive (≥70 U/mL), that is, 10 times upper limit normal. RESULTS: Fifty-nine children (1.3%) were TG2A positive, and of these 31 (53%) had concentrations 70 U/mL or more. Children with TG2A concentrations 70 U/mL or more were less often infected with CMV (adjusted odds ratio (aOR) 0.38, 95% CI 0.14-0.98, P = 0.04) and with any of the 3 viruses (aOR 0.38, 95% CI 0.18-0.78, P < 0.01) than children with TG2A negative concentrations. In addition, children with TG2A concentrations 70 U/mL or more were less often infected with 2 or more viruses than children with TG2A negative concentrations (aOR 0.15, 95% CI 0.03-0.65, P = 0.01). CONCLUSIONS: Both CMV single infection and combined CMV, Epstein-Barr virus and/or herpes simplex virus type 1 infections are inversely associated with strongly TG2A positivity. This may indicate a protective effect of herpesvirus infections in the pathogenesis of celiac disease autoimmunity.

Glutenase ALV003 attenuates gluten-induced mucosal injury in patients with celiac disease.

BACKGROUND & AIMS: Gluten ingestion leads to small intestinal mucosal injury in patients with celiac disease, necessitating strict life-long exclusion of dietary gluten. Despite adherence to a gluten-free diet, many patients remain symptomatic and still have small intestinal inflammation. In this case, nondietary therapies are needed. We investigated the ability of ALV003, a mixture of 2 recombinant gluten-specific proteases given orally, to protect patients with celiac disease from gluten-induced mucosal injury in a phase 2 trial. METHODS: We established the optimal daily dose of gluten to be used in a 6-week challenge study. Then, in the intervention study, adults with biopsy-proven celiac disease were randomly assigned to groups given ALV003 (n = 20) or placebo (n = 21) together with the daily gluten challenge. Duodenal biopsies were collected at baseline and after gluten challenge. The ratio of villus height to crypt depth and densities of intraepithelial lymphocytes were the primary end points. RESULTS: A daily dose of 2 g gluten was selected for the intervention study. Sixteen patients given ALV003 and 18 given placebo were eligible for efficacy evaluation. Biopsies from subjects in the placebo group showed evidence of mucosal injury after gluten challenge (mean villus height to crypt depth ratio changed from 2.8 before challenge to 2.0 afterward; P = .0007; density of CD3(+) intraepithelial lymphocytes changed from 61 to 91 cells/mm after challenge; P = .0003). However, no significant mucosal deterioration was observed in biopsies from the ALV003 group. Between groups, morphologic changes and CD3(+) intraepithelial lymphocyte counts differed significantly from baseline to week 6 (P = .0133 and P = .0123, respectively). There were no statistically significant differences in symptoms between groups. CONCLUSIONS: Based on a phase 2 trial, the glutenase ALV003 appears to attenuate gluten-induced small intestinal mucosal injury in patients with celiac disease in the context of an everyday gluten-free diet containing daily up to 2 g gluten. Clinicaltrial.gov, NUMBERS: NCT00959114 and NCT01255696.

Prevalence of abnormal liver function tests in celiac disease and the effect of a gluten-free diet in the US population.

OBJECTIVES: Guidelines recommend routine screening of liver function tests (LFTs) in patients diagnosed with celiac disease (CD). However, little is known about the prevalence of liver disorders in CD outside of Europe. Our aims were to estimate the prevalence of LFT abnormalities in CD and to evaluate the effect of a gluten-free diet (GFD) on LFTs. METHODS: Adult patients with biopsy-proven CD were identified from a prospectively maintained database and matched with healthy controls. LFT levels for women and men were defined as abnormal based on the Third National Health and Nutrition Examination Survey (NHANES III) criteria. Data on demographics, coexisting liver diseases, and laboratory work-ups including aspartate transaminase (AST) and alanine transaminase (ALT) values at the time of diagnosis and on a GFD were recorded. Subsequently, data from this cohort were compared with data from 7,789 individuals participating in the National Health and Nutrition Examination Survey, 2009-2010. Univariate logistic regression, Wilcoxon signed-ranks, Student's t-test, χ(2), and Fischer's exact test were used for statistical analysis. RESULTS: In 463 CD patients with ALT or AST levels at the time of CD diagnosis, 40.6% had elevated LFTs compared with 24.2% of treated CD patients (P<0.001) and 16.6% of matched controls (P<0.001). Similarly, 36.7% of CD patients on the NHANES database had abnormal ALT values compared with 19.3% of non-celiac patients (P=0.03). Approximately, 78.6% of CD patients with elevated LFTs at diagnosis normalized LFTs on a GFD after a mean duration of 1.5±1.5 years. CONCLUSIONS: Forty percent of individuals will have elevated LFTs at CD diagnosis; however, the majority will normalize with standard CD therapy. LFTs should be checked in all patients with CD and coexisting liver disorder should be considered in patients whose LFTs have not improved within a year on a GFD.

Serum anti-tissue transglutaminase antibodies detected during febrile illness may not be produced by the intestinal mucosa.

Anti-transglutaminase antibodies are the diagnostic marker of celiac disease, and are considered to be synthesized only by intestinal B-lymphocytes. During an infectious disease, these antibodies are transiently detected in serum. We show that these infection-triggered antibodies may not originate in the intestinal mucosa and are not an indication of celiac disease.

[Carbohydrase activities may serve as a marker for small intestinal mucosal recovery in patients with celiac disease].

Aim. To clinically evaluate the activity of glucoamylase, maltase, saccharase, and lactase in the small intestinal mucosa (SIM) of patients with celiac disease. Subjects and methods. Twenty-nine patents with celiac disease were examined. The disease was first detected in 8 patients; in the remaining patients, it had been diagnosed 6 months to 35 years before. The diagnosis was verified by histological examinations of duodenal biopsy specimens and by determination of immunoglobulin (Ig) A and G antibodies to tissue transglutaminase (atTG) and gliadin (AGA) by an enzyme-linked immunosorbent assay (ELISA). Carbohydrase activities were estimated in the duodenal biopsy specimens, by applying the method of A. Dahlquist. Results. In the control group, the activities of glucoamylase, maltase, saccharase, and lactase averaged 598.8+184.2, 825.3+239.3, 180.2-68.1, and 53.4+16.3 ng/glucose/mg tissue min, respectively. In the patients with celiac disease, the average activities of all the examined enteric enzymes were significantly below the normal value even they had been on a gluten-free diet (GFD) for 10 years or longer. Complete SIM structural recovery (Marsh stage 0) occurred in only 7 of 18 patients who had been on a strictly GFD. Serological (atTG and AGA) tests got also negative in all the 7 patients with completely recovered SIM. Six of the latter patients continued to have abdominal bloating and borborygmus, unstable stool with a propensity for diarrhea and weakness. Each was detected to have a lower activity of one or a few enzymes. The activity of all the carbohydrases reached its normal value in only 1 patient and she felt healthy, without perceiving any food intolerance. Conclusion. The activity of membrane enzymes may serve as a marker for the degree of SIM recovery in patients with celiac disease.

[PANCREATIC EXOCRINE INSUFFICIENCY AND ITS CORRECTION IN CHILDREN WITH TYPE I DIABETES IN COMBINATION WITH CELIAC DISEASE].

The results of the examination of patients with type I children,which was diagnosed with celiac disease and pancreatic exocrine insufficiency. To correct the PEN used pancreatin preparations and studied its effectiveness.

Effect of Rothia mucilaginosa enzymes on gliadin (gluten) structure, deamidation, and immunogenic epitopes relevant to celiac disease.

Rothia mucilaginosa, a natural microbial inhabitant of the oral cavity, cleaves gluten (gliadin) proteins at regions that are resistant to degradation by mammalian enzymes. The aim of this study was to investigate to what extent the R. mucilaginosa cell-associated enzymes abolish gliadin immunogenic properties. Degradation of total gliadins and highly immunogenic gliadin 33-mer or 26-mer peptides was monitored by SDS-PAGE and RP-HPLC, and fragments were sequenced by liquid chromatography and electrospray ionization tandem mass spectrometer (LC-ESI-MS/MS). Peptide deamidation by tissue transglutaminase (TG2), a critical step in rendering the fragments more immunogenic, was assessed by TG2-mediated cross-linking to monodansyl cadaverine (MDC), and by a +1-Da mass difference by LC-ESI-MS. Survival of potential immunogenic gliadin epitopes was determined by use of the R5 antibody-based ELISA. R. mucilaginosa-associated enzymes cleaved gliadins, 33-mer and 26-mer peptides into smaller fragments. TG2-mediated cross-linking showed a perfect inverse relationship with intact 33-mer and 26-mer peptide levels, and major degradation fragments showed a slow rate of MDC cross-linking of 6.18 ± 2.20 AU/min compared with 97.75 ± 10.72 and 84.17 ± 3.25 AU/min for the intact 33-mer and 26-mer, respectively, which was confirmed by reduced TG2-mediated deamidation of the fragments in mass spectrometry. Incubation of gliadins with Rothia cells reduced R5 antibody binding by 20, 82, and 97% after 30 min, 2 h, and 5 h, respectively, which was paralleled by reduced reactivity of enzyme-treated 33-mer and 26-mer peptides in the R5 competitive ELISA. Our broad complementary approach to validate gluten degrading activities qualifies R. mucilaginosa-associated enzymes as promising tools to neutralize T cell immunogenic properties for treatment of celiac disease.

Anti-transglutaminase immunoreactivity and histological lesions of the duodenum in coeliac patients.

Coeliac disease (CD) is characterized by several markers, including anti-transglutaminase auto-antibodies (tTGAb) directed against multiple epitopes of the gliadin protein. We aimed to investigate the correlation among CD duodenal lesions, tTGAb titres and the immunoreactivity against tTG constructs. A total of 345 CD patients (209 females, 136 males, overall median age: 7.3 years) were tested for full-length (fl) tTGAb with a fluid-phase radioimmunoassay. Out of the total, 231 patients were also tested for immunoreactivity against tTG fragments (F1: a.a. 227-687 and F2: a.a. 473-687). Patients were classified according to diffuse (D), patchy (P) or bulb (B) histological lesions. All sera were found fltTGAb positive. Patients with D, P and B lesions had a mean Ab index of 0.84±0.39, 0.57±0.39 and 0.45±0.24, respectively. Mean tTGAb titre varied between D and localized (P+B) patients (0.84±0.39 versus 0.52±0.34, P < 0.0001). Overall, 86.1% of patients were F1 auto-antibody (F1Ab) positive (D: 89%, P: 75%, B: 40%; D versus P+B: P = 0.004) and 49% of patients were F2 auto-antibody (F2Ab) positive (D: 53%, P: 19%, B: 10%; D versus P+B: P = 0.0006). Of the D patients 50.7% showed combined F1Ab-F2Ab (D versus P+B: P = 0.001), whereas 60% of B patients were negative for both F1Ab and F2Ab (B versus D: P < 0.0001). Coeliac-specific tTGAb immunoreactivity correlates with the grading and extension of histological duodenal lesions in CD patients at diagnosis. The immunoreactivity against single and combined tTG fragments is significantly higher in patients with D lesions. This is the first evidence of a distinct coeliac-specific immunoreactivity in patients with different duodenal involvement.

Small bowel transglutaminase 2-specific IgA deposits in dermatitis herpetiformis.

Dermatitis herpetiformis (DH) is an extraintestinal manifestation of coeliac disease. Untreated coeliac disease patients are known to have transglutaminase 2 (TG2)-targeted IgA deposits in the small bowel mucosa. To evaluate whether similar intestinal IgA deposits are also present in DH and whether the deposits disappear with gluten-free diet, 47 untreated and 27 treated DH patients were studied. Seventy-nine percent of untreated and 41% of the treated DH patients had TG2-specific IgA deposits in the small bowel, and the presence of the deposits showed a significant association with the degree of small bowel villous atrophy (p < 0.001). Other coeliac-disease related inflammatory markers were also investigated, and the density of small bowel mucosal intraepithelial γδ(+) T cells was increased in 91% of untreated and 73% of treated DH patients. The results show that the majority of untreated DH patients have similar gluten-dependent TG2-specific IgA deposits the small bowel mucosa as coeliac disease patients.

In vivo fluorescence imaging of exogenous enzyme activity in the gastrointestinal tract.

Exogenous enzymes are administered orally to treat several diseases, such as pancreatic insufficiency and lactose intolerance. Due to the proteinaceous nature of enzymes, they are subject to inactivation and/or digestion in the gastrointestinal (GI) tract. Here we describe a convenient fluorescence-based assay to monitor the activity of therapeutic enzymes in real time in vivo in the GI tract. To establish the proof of principle, the assay was applied to proline-specific endopeptidases (PEPs), a group of enzymes recently proposed as adjuvant therapy for celiac disease (a highly prevalent immunogenetic enteropathy). A short PEP-specific peptide sequence which is part of larger immunotoxic sequences of gluten was labeled with a fluorescent dye and a corresponding quencher. Upon enzymatic cleavage, the fluorescence emission was dequenched and detected with an in vivo imaging system. PEPs originating from Flavobacterium meningosepticum (FM) and Myxococcus xanthus (MX) were evaluated after oral administration in rats. While MX PEP could not cleave the peptide in the stomach, FM PEP showed significant gastric activity reaching 40-60% of the maximal in vivo signal intensity. However, both enzymes produced comparable fluorescence signals in the small intestine. Coadministration of an antacid drug significantly enhanced MX PEP's gastric activity due to increased pH and/or inhibition of stomach proteases. With this simple procedure, differences in the in vivo performance of PEPs, which could not be identified under in vitro conditions, were detected. This imaging assay could be used to study other oral enzymes in vivo and therefore be instrumental in improving their therapeutic efficiency.

Scalloping is a reliable endoscopic marker for celiac disease.

BACKGROUND: Scalloping of duodenal folds noted on esophagogastroduodenoscopy (EGD) has been associated with various illnesses including celiac disease (CD). The aim of the present study was to examine the frequency of scalloping in pediatric patients undergoing EGD and to assess its significance in the diagnosis of CD. We also evaluated the association of scalloping with the histopathology and celiac serology in the subgroup of celiac patients. PATIENTS AND METHODS: All children (0-18 years) who underwent EGD at Shaare Zedek Medical Center for any reason during a 2.5-year period were retrospectively included, yielding a consecutive cohort without selection bias. Relevant data were obtained from the patient files. RESULTS: During the study period, 623 children underwent EGD of whom 149 (24%) were eventually diagnosed with CD. In 74/623children (12%), scalloping was seen and had a sensitivity of 48% (95% CI 0.40-0.57), specificity of 99% (0.98-0.99) and positive predictive value of 97% (0.9-0.99) to diagnose CD. The prevalence of scalloping increased with advancing stage of the Marsh classification from 33% (7/21) in Marsh 1 to 63% (34/54) in Marsh 3c (P < 0.001). Scalloping was associated with a significantly higher median tissue transglutaminase level (153 [IQR 98-168] versus 49 [IQR 11-143]; P = 0.011). CONCLUSION: The results suggest that the diagnosis of CD is almost certain if isolated scalloping is observed during EGD done to rule out CD. Thus, attention to this finding may serve as an additional tool in the diagnosis of CD.