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Lindeman I, Sollid LM. Single-cell approaches to dissect adaptive immune responses involved in autoimmunity: the case of celiac disease. Mucosal Immunol 2022; 15:51-63. [PMID: 34531547 DOI: 10.1038/s41385-021-00452-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 02/04/2023]
Abstract
Single-cell analysis is a powerful technology that has found widespread use in recent years. For diseases with involvement of adaptive immunity, single-cell analysis of antigen-specific T cells and B cells is particularly informative. In autoimmune diseases, the adaptive immune system is obviously at play, yet the ability to identify the culprit T and B cells recognizing disease-relevant antigen can be difficult. Celiac disease, a widespread disorder with autoimmune components, is unique in that disease-relevant antigens for both T cells and B cells are well defined. Furthermore, the celiac disease gut lesion is readily accessible allowing for sampling of tissue-resident cells. Thus, disease-relevant T cells and B cells from the gut and blood can be studied at the level of single cells. Here we review single-cell studies providing information on such adaptive immune cells and outline some future perspectives in the area of single-cell analysis in autoimmune diseases.
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Affiliation(s)
- Ida Lindeman
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway.,Department of Immunology, Oslo University Hospital, Oslo, Norway
| | - Ludvig M Sollid
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway. .,Department of Immunology, Oslo University Hospital, Oslo, Norway. .,Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
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Lindeman I, Zhou C, Eggesbø LM, Miao Z, Polak J, Lundin KE, Jahnsen J, Qiao SW, Iversen R, Sollid LM. Longevity, clonal relationship, and transcriptional program of celiac disease-specific plasma cells. J Exp Med 2021; 218:e20200852. [PMID: 33095260 PMCID: PMC7590513 DOI: 10.1084/jem.20200852] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/07/2020] [Accepted: 09/30/2020] [Indexed: 12/11/2022] Open
Abstract
Disease-specific plasma cells (PCs) reactive with transglutaminase 2 (TG2) or deamidated gluten peptides (DGPs) are abundant in celiac disease (CeD) gut lesions. Their contribution toward CeD pathogenesis is unclear. We assessed expression of markers associated with PC longevity in 15 untreated and 26 treated CeD patients in addition to 13 non-CeD controls and performed RNA sequencing with clonal inference and transcriptomic analysis of 3,251 single PCs. We observed antigen-dependent V-gene selection and stereotypic antibodies. Generation of recombinant DGP-specific antibodies revealed a key role of a heavy chain residue that displays polymorphism, suggesting that immunoglobulin gene polymorphisms may influence CeD-specific antibody responses. We identified transcriptional differences between CeD-specific and non-disease-specific PCs and between short-lived and long-lived PCs. The short-lived CD19+CD45+ phenotype dominated in untreated and short-term-treated CeD, in particular among disease-specific PCs but also in the general PC population. Thus, the disease lesion of untreated CeD is characterized by massive accumulation of short-lived PCs that are not only directed against disease-specific antigens.
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Affiliation(s)
- Ida Lindeman
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Chunyan Zhou
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi, China
| | - Linn M. Eggesbø
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Zhichao Miao
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Cambridge, UK
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
- Translational Research Institute of Brain and Brain-Like Intelligence and Department of Anesthesiology, Shanghai Fourth People's Hospital (affiliated with Tongji University School of Medicine), Shanghai, China
| | - Justyna Polak
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Knut E.A. Lundin
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
- Department of Gastroenterology, Oslo University Hospital-Rikshospitalet, Oslo, Norway
| | - Jørgen Jahnsen
- Department of Gastroenterology, Akershus University Hospital, Lørenskog, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Shuo-Wang Qiao
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Rasmus Iversen
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Ludvig M. Sollid
- KG Jebsen Coeliac Disease Research Centre, University of Oslo, Oslo, Norway
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
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Martín-Yerga D, Costa-García A. Towards a blocking-free electrochemical immunosensing strategy for anti-transglutaminase antibodies using screen-printed electrodes. Bioelectrochemistry 2015; 105:88-94. [DOI: 10.1016/j.bioelechem.2015.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 05/20/2015] [Accepted: 05/20/2015] [Indexed: 01/26/2023]
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Martín-Yerga D, González-García MB, Costa-García A. Electrochemical immunosensor for anti-tissue transglutaminase antibodies based on the in situ detection of quantum dots. Talanta 2014; 130:598-602. [DOI: 10.1016/j.talanta.2014.07.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 06/30/2014] [Accepted: 07/02/2014] [Indexed: 10/25/2022]
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Gelderman KA, Drop ACAD, Trouw LA, Bontkes HJ, Bouma G, van Hoogstraten IMW, von Blomberg BME. Serum autoantibodies directed against transglutaminase-2 have a low avidity compared with alloantibodies against gliadin in coeliac disease. Clin Exp Immunol 2014; 177:86-93. [PMID: 24666357 DOI: 10.1111/cei.12302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2014] [Indexed: 12/19/2022] Open
Abstract
Coeliac disease is characterized by intolerance to gliadin and related gluten components present in wheat, barley and rye. Coeliac disease patients harbour antibodies directed against alloantigens such as gliadin, but also against the autoantigen transglutaminase-2 (TG2). The type and quality of antibody responses provides insight into the underlying immune activation processes. Therefore, in this study we have analysed the avidity of the antibody response directed against the autoantigen TG2 and compared this with antibody responses against the alloantigens gliadin and Escherichia coli. We observed that the immunoglobulin (Ig)A autoantibody response directed against TG2 is of low avidity compared with the IgA response against the alloantigens gliadin and E. coli in the same patients; the same was true for IgG, both in IgA-deficient and in -sufficient coeliac patients. The observed avidities appear not to be related to disease stage, antibody levels, age or duration of exposure to gluten. In conclusion, in coeliac disease there is a clear difference in avidity of the antibody responses directed against the auto- and alloantigens, indicating different regulation or site of initiation of these responses.
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Affiliation(s)
- K A Gelderman
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
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Picarelli A, Di Tola M, Marino M, Libanori V, Borghini R, Salvi E, Donato G, Vitolo D, Tiberti A, Marcheggiano A, Bassotti G, Corazziari E. Usefulness of the organ culture system when villous height/crypt depth ratio, intraepithelial lymphocyte count, or serum antibody tests are not diagnostic for celiac disease. Transl Res 2013. [PMID: 23177794 DOI: 10.1016/j.trsl.2012.10.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The existence of mild forms of celiac disease (CD) can make the histology-based diagnosis difficult to reach. Since anti-endomysium (EMA) and anti-tissue transglutaminase (anti-tTG) are detectable in culture supernatants of duodenal biopsies from CD patients, our aim was to assess if this system can support the histology in the diagnostic work-up. A total of 559 suspected CD patients underwent serum EMA/anti-tTG detection, upper endoscopy with duodenal biopsy sampling, histologic analysis, and organ culture to detect EMA/anti-tTG in supernatants. A subgroup of 30 patients with organ culture positive results were put on a gluten-free diet (GFD). Their gluten-dependency was evaluated by the psychological general well-being and beck depression inventory indexes. Statistical analysis was performed by Cohen k inter-test, Friedman test, and Dunn multiple comparison. Two hundred forty-one out of 559 (43.1%) patients showed intestinal villous atrophy, whereas serum and organ culture EMA/anti-tTG were positive in 293/559 (52.4%) and 334/559 (59.7%) patients, respectively. The strength of agreement resulted good for serology vs histology (k = 0.730), good for organ culture vs histology (k = 0.662), and very good for serology vs organ culture (k = 0.852). After 12 months of GFD, psychological general well-being index significantly increased, and beck depression inventory index significantly decreased (P < 0.001 for each one). Data highlight the organ culture system as a useful tool to assist the histology in diagnosing CD, mainly in cases without villous atrophy or in seronegative patients. The marked improvement in quality of life after a GFD further supports the reliability of this system in diagnosing CD.
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Affiliation(s)
- Antonio Picarelli
- Department of Internal Medicine and Medical Specialties, Sapienza University, 00161 Rome, Italy.
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Immunological comorbity in coeliac disease: associations, risk factors and clinical implications. J Clin Immunol 2012; 32:984-90. [PMID: 22526595 DOI: 10.1007/s10875-012-9693-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Accepted: 04/03/2012] [Indexed: 02/06/2023]
Abstract
PURPOSE Coeliac disease is frequently associated with other immunomediated diseases. Our aim was to identify immunological comorbidities and possible risk factors for their development in coeliac patients. METHODS We recruited a cohort of 1,015 coeliac patients followed from 0 to 46 years in a single tertiary referral centre. Data were collected from the yearly scheduled clinical and serological evaluations. Possible risk factors such as demographic parameters, type of symptomatic presentation, gluten exposure, gluten-free diet compliance and family history were all evaluated. Subjects (848,606) from the regional health registry were investigated as controls. RESULTS The prevalence of immunomediated diseases was higher in patients with coeliac disease compared to the registry population (23 % vs 0.4 %, p < 0.001). Diagnosis during paediatric age represented a risk factor for the presence of at least an immunomediated disease (hazard ratio = 1.62, 95 % confidence interval 1.15-2.29, p = 0.0061). Type of presentation and dietetic compliance did not represent risk factors. Long-standing gluten exposure reduced the risk of developing immunomediated diseases in coeliac subjects (hazard ratio for 1 year longer exposure 0.23, 95 % confidence interval 0.16-0.33, p < 0.0001). A familiar background characterized by the presence of immunological disorders was not a risk factor, although 419 (13 %) first degree relatives of coeliac patients out of 3,195 had an immunomediated disease. CONCLUSIONS Our study suggests the need to investigate coeliac patients for other associated immunomediated diseases, independently of sex, gluten exposure and compliance to therapy; also subjects diagnosed in paediatric age should be carefully screened during follow up.
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Rathsman S, Tysk C, Eriksson S, Hultgren O, Åberg AK, Olcén P. Elution of antitransglutaminase antibodies from duodenal biopsies: a novel approach in the diagnosis of celiac disease. APMIS 2012; 120:666-74. [DOI: 10.1111/j.1600-0463.2012.02884.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 12/28/2011] [Indexed: 12/20/2022]
Affiliation(s)
- Sandra Rathsman
- Department of Laboratory Medicine/Microbiology; Örebro University Hospital; Örebro; Sweden
| | | | - Sune Eriksson
- Department of Laboratory Medicine/Pathology; Örebro University Hospital; Örebro; Sweden
| | | | - Anna-Karin Åberg
- Department of Laboratory Medicine/Microbiology; Örebro University Hospital; Örebro; Sweden
| | - Per Olcén
- Department of Laboratory Medicine/Microbiology; Örebro University Hospital; Örebro; Sweden
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Neves MM, González-García MB, Nouws HP, Costa-García A. Celiac disease detection using a transglutaminase electrochemical immunosensor fabricated on nanohybrid screen-printed carbon electrodes. Biosens Bioelectron 2012; 31:95-100. [DOI: 10.1016/j.bios.2011.09.044] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/26/2011] [Accepted: 09/29/2011] [Indexed: 12/18/2022]
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Role of polyamines, their analogs and transglutaminases in biological and clinical perspectives. Amino Acids 2011; 42:397-409. [DOI: 10.1007/s00726-011-1129-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 09/26/2011] [Indexed: 01/07/2023]
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Autoantibodies from patients with celiac disease inhibit transglutaminase 2 binding to heparin/heparan sulfate and interfere with intestinal epithelial cell adhesion. Amino Acids 2011; 42:1055-64. [DOI: 10.1007/s00726-011-1020-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 05/26/2011] [Indexed: 11/26/2022]
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Barbato M, Maiella G, Di Camillo C, Guida S, Valitutti F, Lastrucci G, Mainiero F, Cucchiara S. The anti-deamidated gliadin peptide antibodies unmask celiac disease in small children with chronic diarrhoea. Dig Liver Dis 2011; 43:465-9. [PMID: 21257356 DOI: 10.1016/j.dld.2010.12.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 11/13/2010] [Accepted: 12/08/2010] [Indexed: 12/11/2022]
Abstract
OBJECTIVES To assess the usefulness of a new class of antibodies, the anti-deamidated gliadin peptides, in the diagnostic approach to children less than 2 years with suspected celiac disease. PATIENTS AND METHODS We investigated 40 children (median age: 16.8 months; age range: 4-24 months), with symptoms and signs of chronic enteropathy and high serum levels of conventional anti-gliadin antibodies, but normal values of anti-transglutaminase and anti-endomysial antibodies; all underwent measurement of anti-deamidated gliadin peptides serum levels, upper gastrointestinal endoscopy with biopsies and HLA typing; 40 subjects served as controls. RESULTS In 29 patients (group A) serum levels of anti-deamidated gliadin peptides were normal and duodenal histology showed a spectrum of abnormalities ranging from mucosal inflammatory infiltrates to villous damage (in almost all cases compatible with Marsh 1-to-2 lesions). All improved on a cow's and soy milk free diet containing gluten. In 11 patients (group B) there were high serum levels of anti-deamidated gliadin peptides and histology showed features suggestive of celiac disease (Marsh 2-to-3 lesions) in all; furthermore, human leucocyte antigen typing was consistent with a celiac disease genetic pattern in all. Group B patients significantly improved on a gluten free diet containing cow's and soy milk proteins. None of the control group was anti-deamidated gliadin peptides positive. CONCLUSIONS In children younger than 2 years with signs of chronic enteropathy and normal values of classical serum markers of celiac disease, the latter can be predicted by high serum levels of anti-deamidated gliadin peptides.
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Affiliation(s)
- Maria Barbato
- Department of Pediatrics, Pediatric Gastroenterology and Liver Unit, Sapienza University of Rome, Rome, Italy
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Galactosylation of serum IgA1 O-glycans in celiac disease. J Clin Immunol 2010; 31:74-9. [PMID: 20938724 DOI: 10.1007/s10875-010-9473-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 09/24/2010] [Indexed: 02/01/2023]
Abstract
In celiac disease, gluten ingestion provokes small-bowel mucosal injury and production of IgA autoantibodies against transglutaminase 2 (TG2). It has been suggested that in celiac patients IgA could mediate the transepithelial passage of gluten peptides in a mechanism involving the transferrin receptor. As IgA1 with galactose-deficient O-linked glycans has elevated affinity for the transferrin receptor, we assessed whether total serum IgA1 and IgA1 anti-TG2 autoantibodies in celiac patients are aberrantly glycosylated. We report that males with celiac disease have higher total serum levels of galactose-deficient IgA1 than non-celiac males. Furthermore, O-glycans of the disease-specific TG2 IgA1 autoantibodies in celiac patients exhibited elevated galactose deficiency. A gluten-free diet had no effect on the total serum levels of galactose-deficient IgA1, whereas the amount of galactose-deficient anti-TG2 IgA1 decreased. Thus, the undergalactosylated IgA1 molecules are not pathognomonic for celiac disease, but galactose deficiency in IgA1 could be an aggravating factor.
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Transglutaminase 2-targeted autoantibodies in celiac disease: Pathogenetic players in addition to diagnostic tools? Autoimmun Rev 2010; 9:744-9. [DOI: 10.1016/j.autrev.2010.06.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Accepted: 06/08/2010] [Indexed: 12/12/2022]
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Abstract
Inflammatory arthritis presents in a variety of diseases, from rheumatoid arthritis to hepatitis. Antibodies to autoantigens or to microbial constituents are commonly associated with these conditions. In some cases, the antibodies have diagnostic and prognostic relevance. It cannot as yet be determined definitively that any of them mediate joint damage, although the evidence from animal models indicates that this mechanism is likely. The purpose of this article is to give an overview of the spectrum of antibodies found in a variety of inflammatory arthritides. The relevant animal models are also discussed.
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Affiliation(s)
- Ann Duskin
- Department of Medicine, Pennsylvania Hospital, Philadelphia, PA, USA
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Hodrea J, Demény MA, Majai G, Sarang Z, Korponay-Szabó IR, Fésüs L. Transglutaminase 2 is expressed and active on the surface of human monocyte-derived dendritic cells and macrophages. Immunol Lett 2010; 130:74-81. [PMID: 20005901 DOI: 10.1016/j.imlet.2009.12.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 11/27/2009] [Accepted: 12/02/2009] [Indexed: 11/25/2022]
Abstract
The multifunctional enzyme, transglutaminase 2 (TG2), can be found intracellularly, in the extracellular matrix and on the cell surface. Cell surface TG2 (csTG2) could not be detected by TG2-specific antibodies or autoantibodies on immunocompetent cells. A supposedly csTG2-specific antibody, 6B9, was recently shown to actually react with CD44. Though the importance of TG2-mediated deamidation of gluten in the pathogenesis of celiac disease has been well recognized, it is not known in which intestinal cells or cell compartment the deamidation occurs. Duodenal dendritic cells (DCs) can be directly involved in gluten-reactive T-cell activation. Here we use blood monocyte-derived dendritic cells (iDC) and macrophages (MPhi) as a model for intestinal antigen-presenting cells (APCs) and show that they contain large amounts of TG2. We found that TG100, a commercial TG2-specific monoclonal antibody can recognize TG2 on the surface of these cells, that is monocyte-derived APCs express surface-associated TG2. TG2 expression was found on the surface of individual tunica propria cells in frozen small bowel tissue sections from both normal and celiac subjects. We also demonstrate that the pool of TG2 on the surface of iDCs can be catalytically active, hence it might directly be involved in the deamidation of gliadin peptides. Bacterial lipopolysaccharide (LPS) increased the level of TG2 on the surface of maturing DCs, supporting the hypothesis that an unspecific inflammatory process in the gut may expose more transglutaminase activity.
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Affiliation(s)
- Judit Hodrea
- Department of Biochemistry and Molecular Biology, Hungarian Academy of Sciences, University of Debrecen, Debrecen, Hungary
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Király R, Csosz E, Kurtán T, Antus S, Szigeti K, Simon-Vecsei Z, Korponay-Szabó IR, Keresztessy Z, Fésüs L. Functional significance of five noncanonical Ca2+-binding sites of human transglutaminase 2 characterized by site-directed mutagenesis. FEBS J 2009; 276:7083-96. [PMID: 19878304 DOI: 10.1111/j.1742-4658.2009.07420.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The multifunctional tissue transglutaminase 2 (TG2) has a four-domain structure with several Ca(2+)-regulated biochemical activities, including transglutamylation and GTP hydrolysis. The structure of the Ca(2+)-binding form of the human enzyme is not known, and its Ca(2+)-binding sites have not been fully characterized. By mutagenesis, we have targeted its active site Cys, three sites based on homology to Ca(2+)-binding residues of epidermal transglutaminase and factor XIIIa (S1-S3), and two regions with negative surface potentials (S4 and S5). CD spectroscopy, antibody-binding assay and GTPase activity measurements indicated that the amino acid substitutions did not cause major structural alterations. Calcium-45 equilibrium dialysis and isothermal calorimetric titration showed that both wild-type and active site-deleted enzymes (C277S) bind six Ca(2+). Each of the S1-S5 mutants binds fewer than six Ca(2+), S1 is a strong Ca(2+)-binding site, and mutation of one site resulted in the loss of more than one bound Ca(2+), suggesting cooperativity among sites. All mutants were deficient in transglutaminase activity, and GTP inhibited remnant activities. Like those of the wild-type enzyme, the GTPase activities of the mutants were inhibited by Ca(2+), except in the case of the S4 and S5 mutants, which exhibited increased activity. TG2 is the major autoantigen in celiac disease, and testing the reactivity of mutants with autoantibodies from celiac disease patients revealed that S4 strongly determines antigenicity. It can be concluded that five of the Ca(2+)-binding sites of TG2 influence its transglutaminase activity, two sites are involved in the regulation of GTPase activity, and one determines antigenicity for autoantibodies in celiac patients.
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Affiliation(s)
- Róbert Király
- Apoptosis and Genomics Research Group of Hungarian Academy of Sciences, Debrecen, Hungary.
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