Humoral Immune Response to Tissue Transglutaminase Is Related to Epithelial Cell Proliferation in Celiac Disease (original) (raw)
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Immunome Research, 2015
Tissue transglutaminase is a multifunctional enzyme, exerting intra and extracellular, enzymatic and nonenzymatic, Ca 2+ dependent and independent functions. Its specific autoantibody, the anti transglutaminase2 autoantibody is multifunctional, affecting many of the enzyme activities. Most of them are due to loss of function, the minority being gain of function of the enzyme. No beneficial protective effects, but only pathogenic ones, were assigned to those celiac disease associated anti TG2 autoantibodies. Taken together, celiac antibodies could collectively promote small bowel intestinal or extraintestinal damage. Yet, most of the transglutaminase2 autoantibody activities where explored in vitro and ex-vivo, very few in animal model but none in vivo, in human. The celiac disease serum contains numerous antibodies, IgA-transglutaminase2 is only one of them and up till now, its differential role in celiac disease induction and maintenance is far from being unraveled. Unraveling them might open some new therapeutic strategies for celiac disease.
Unexpected Role of Surface Transglutaminase Type II in Celiac Disease
Gastroenterology, 2005
In celiac disease (CD), transglutaminase type II (TG2) has 2 fundamental roles: (1) as the autoantigen recognized by highly specific autoantibodies and (2) the modifier of pathogenic gliadin T-cell epitopes. It follows that inhibition of TG2 might represent an attractive strategy to curb the toxic action of gliadin. Here we studied the validity of this strategy using the organ culture approach. Methods: Duodenal biopsy specimens from 30 treated patients with CD, 33 untreated patients with CD, and 24 controls were cultured with or without gliadin peptides p31-43, p␣-9, and deamidated p␣-9 for 20 minutes, 3 hours, and 24 hours. In 31 patients with CD and 16 controls, TG2 inhibitor R283 or anti-TG CUB 7402 or anti-surface TG2 (6B9) mAbs were used in cultures. T84 cells were also cultured with or without peptides with or without TG inhibitors. Mucosal modifications after culture were assessed by immunofluorescence, in situ detection of TG activity, confocal microscopy, and fluorescence-activated cell sorter analysis. Results: The enzymatic inhibition of TG2 only controlled gliadin-specific T-cell activation. The binding of surface TG2 contained gliadin-specific T-cell activation and p31-43-induced actin rearrangement, epithelial phosphorylation, and apoptosis, both in organ cultures and T84 cells. Conclusions: These data indicate a novel and unexpected biological role for surface TG2 in the pathogenesis of CD suggesting a third role for TG2 in CD. These results have a specific impact for celiac disease, with wider implications indicating a novel biologic function of TG2 with possible repercussions in other diseases.
Nature Medicine, 2012
Celiac disease (CD) is an immune mediated disorder in which mucosal autoantibodies to the enzyme transglutaminase 2 (TG2) 1 are generated in response to the exogenous antigen gluten 2 in individuals who are HLA-DQ2 or HLA-DQ8 3. We assessed in a comprehensive and non-biased manner the IgA anti-TG2 response by expression cloning of the antibody repertoire on ex vivo isolated intestinal antibody-secreting cells (ASCs). We found that TG2-specific plasma cells are hugely expanded in patients with active CD, representing on average 10% of ASCs within the duodenal mucosa. Surprisingly, anti-TG2 antibodies were of high affinity and yet showed little adaptation by somatic mutations. Unlike infection-induced peripheral blood plasmablasts 4 , the TG2-specific ASCs had neither recently proliferated nor were they short-lived ex vivo. Altogether these observations demonstrate that there is a germline repertoire with high affinity for TG2 that may favour massive generation of autoreactive B cells. Anti-TG2 antibodies did not block enzymatic activity and served as substrates for TG2-mediated crosslinking when expressed as IgD or IgM, but not as IgA1 or IgG1. This could result in preferential recruitment of plasma cells from Users may view, print, copy, download and text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:
Fluctuating transglutaminase autoantibodies are related to histologic features of celiac disease
Clinical Gastroenterology and Hepatology, 2003
Background & Aims: Asymptomatic children at risk for celiac disease (CD) and seropositive for immunoglobulin A anti-TG autoantibodies (TGAA) may lack small intestinal mucosal changes characteristic of CD. We have followed a group of children with serial testing for TGAA. Methods: Subjects were a group of at-risk children comprised of infants expressing HLA-DR3 on newborn screening, those with type 1A diabetes, or a first-degree relative of someone with type 1 diabetes. All children participating in the prospective study for development of CD underwent serial testing for TGAA. Data from clinical evaluation and small intestinal biopsy were compared to the TGAA levels followed over time. Results: In 42 children, serial TGAA determinations while on a glutencontaining diet showed levels fluctuating 10 -100-fold over 3-12 months. A TGAA index more than 0.5 had a positive predictive value (PPV) for histologic confirmation of CD of 96% (22/23). A TGAA index above the usual cutoff for positivity (0.05) had a PPV of only 76% (28/37). Conclusions: In children with TGAA seropositivity, the TGAA level varied over time and a higher titer predicted an abnormal biopsy characteristic of CD. A threshold for biopsy for diagnosis of CD could be set higher for screening-identified cases than for clinically identified cases to decrease the frequency of performing "normal" biopsies.
Mucosal tissue transglutaminase expression in celiac disease
Journal of Cellular and Molecular Medicine, 2009
Tissue transglutaminase (tTG) plays an important role in celiac disease pathogenesis and antibodies to tTG are a diagnostic marker of gluten sensitive enteropathy. The aim of this study was to investigate the localization of tTG in the duodenal mucosa in control tissues and in differ ent histological stages of celiac disease by using a commercial and a novel set of ant¡-tTG monoclonal antibodies, to see whether this assess ment can be useful for diagnostic purpose. The distribution of tTG was firstly evaluated in 18 untreated celiac patients by using a commer cial monoclonal antibody (CUB7402) against tissue transglutaminase enzyme and directed against the loop-core region of the enzyme. Thereafter, in further 30 untreated celiac patients we employed three newly characterized anti-tTG monoclonal antibodies produced against recombinant human-tTG. The epitopes recognized are located in three distinct domains of the protein corresponding to the core, C1 and C2 protein structure. Eleven age-and sex-matched patients with chronic duodenitis acted as controls. All subjects underwent upper endoscopy to obtain biopsy samples from the duodenum. Overall, we found that (/') tTG is equally expressed in CD at different stages of disease; (/'/') tTG is expressed, at similar level, in CD and controls with duodenitis. Assessment of tTG level in biopsy samples by immunohistochemical methods is not useful in the clinical diagnostic work-up of CD.
Coeliac disease autoantibodies mediate significant inhibition of tissue transglutaminase
Clinical Immunology, 2010
The detection of antibodies directed against tissue transglutaminase (tTG) in serum is a sensitive and specific test for suspected coeliac disease. tTG is a ubiquitous, multifunctional enzyme that has been implicated in many important physiological processes as well as the sitespecific deamidation of glutamine residues in gluten-derived peptides. This modification of gluten peptides facilitates their binding to HLA-DQ2, which results in amplification of the T-cell response to gluten. The purpose of this study was to investigate the possibility that patient IgA autoantibodies directed against tTG interfere with the crosslinking activity of the enzyme. IgA autoantibodies against tTG were isolated/depleted from patient serum and tested for their capacity to interfere with tTG activity in vitro using a sensitive fluorescence-based activity assay. We have demonstrated that autoantibodies cause significant inhibition of tTG-mediated crosslinking at equimolar and 2:1 ratios of antibody to enzyme.