Anti-tissue transglutaminase antibodies from coeliac patients inhibit transglutaminase activity both in vitro and in situ

Esposito, Carla; Paparo, Francesco; Caputo, Ivana; Rossi, Mauro; Maglio, Mariantonia; Sblattero, Daniele; Not, Tarcisio; Porta, Raffaele; Auricchio, Salvatore; Marzari, Roberto; Troncone, Riccardo

doi:10.1136/gut.51.2.177

Cited by 112 publications

(67 citation statements)

References 33 publications

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“…This increase in K m is compatible with competitive inhibition of enzyme activity (26). A similar phenomenon of inhibition of enzymes by autoantibodies to transglutaminase and mitochondrial M2 has previously been described (27,28).…”

Section: Anti-aldolase Positive Serum Inhibits Enzyme Activitysupporting

confidence: 54%

Identification of Aldolase as a Target Antigen in Alzheimer’s Disease

Mor

Izak

Cohen

2005

The Journal of Immunology

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Alzheimer’s disease (AD) is the most common human neurodegenerative disease, leading to progressive cognitive decline and eventually death. The prevailing paradigm on the pathogenesis of AD is that abnormally folded proteins accumulate in specific brain areas and lead to neuronal loss via apoptosis. In recent years it has become evident that an inflammatory and possibly autoimmune component exists in AD. Moreover, recent data demonstrate that immunization with amyloid-β peptide is therapeutically effective in AD. The nature of CNS Ags that are the target of immune attack in AD is unknown. To identify potential autoantigens in AD, we tested sera IgG Abs of AD patients in immunoblots against brain and other tissue lysates. We identified a 42-kDa band in brain lysates that was detected with >50% of 45 AD sera. The band was identified by mass spectrometry to be aldolase A. Western blotting with aldolase using patient sera demonstrated a band of identical size. The Ab reactivity was verified with ELISAs using aldolase. One of 25 elderly control patients and 3 of 30 multiple sclerosis patients showed similar reactivity (p < 0.002). In enzymatic assays, anti-aldolase positive sera were found to inhibit the enzyme’s activity, and the presence of the substrate (fructose 1,6-diphosphate) enhanced Ab binding. Immunization of rats and mice with aldolase in complete Freund’s adjuvant was not pathogenic. These findings reveal an autoimmune component in AD, point at aldolase as a common autoantigen in this disease, and suggest a new target for potential immune modulation.

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Section: Anti-aldolase Positive Serum Inhibits Enzyme Activitysupporting

confidence: 54%

Identification of Aldolase as a Target Antigen in Alzheimer’s Disease

Mor

Izak

Cohen

2005

The Journal of Immunology

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“…On the 3rd and 12th day post-confluence, cells were used for in situ treatments and alternatively were harvested to perform in vitro assays. A stable MDCK cell clone, MDCK-tTG, expressing recombinant tTG was previously obtained (26) and used for in situ assays.…”

Section: Methodsmentioning

confidence: 99%

Proteomics Identification of Acyl-acceptor and Acyl-donor Substrates for Transglutaminase in a Human Intestinal Epithelial Cell Line

Orrú

Caputo

D’Amato

et al. 2003

Journal of Biological Chemistry

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Transglutaminase (TG)-catalyzed cross-linking of both intracellular and extracellular proteins is an important biochemical event. However, increased concentrations of cross-linked proteins have been observed in many disorders. Moreover, TG-catalyzed modification of proteins might generate new self-antigens responsible for the autoimmune response, as in celiac disease. The identification of available substrates may offer an understanding of how the TG-catalyzed post-translational modification has an impact on physiology and disease. We used a proteomic approach to identify TG-modified protein targets in human intestinal epithelial cells to determine the extent to which transglutaminase specifically contributes to celiac disease. Two probes were used for endogenous TG activity: 5-(biotinamido)pentylamine, which represents the acyl-acceptor, and a biotinylated glutamine-containing peptide, which represents the acyl-donor. This approach identified >25 proteins, which range from 30,000 to 300,000 Daltons and can serve as acyl-acceptor and/or acyl-donor for transglutaminase. Some of them were known transglutaminase substrates, whereas others had not been previously identified. These targets include proteins involved in cytoskeletal network organization, folding of proteins, transport processes, and miscellaneous metabolic functions.

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“…25 In contrast, another study failed to demonstrate any inhibitory effect of total serum IgA and IgG of patients with CD when tested with purified human tTG. 24 These results with total IgA and IgG class antibodies were confirmed by our data.…”

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confidence: 96%

Autoantibodies of patients with coeliac disease are insufficient to block tissue transglutaminase activity

Dieterich

Trapp²,

Esslinger³

et al. 2003

Gut

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Background and aims: Coeliac disease (CD) is characterised by the presence of autoantibodies against tissue transglutaminase (tTG), the endomysial autoantigen. This study was performed to determine the effect of purified autoantibodies on the enzymatic activity of tTG. Methods: Total IgA and IgG class antibodies and purified anti-tTG autoantibodies were isolated from sera of untreated patients with CD and controls. The inhibitory capacity of the antibodies on tTG activity was checked by a fluorometric assay based on the incorporation of monodansyl cadaverine into casein and by tTG-catalysed cross linking of biotinylated cadaverine to gliadin. Results: The enriched IgA and IgG fractions of five patients with CD and three controls resulted in no significantly different inhibition of enzymatic activity. In contrast, the use of affinity purified anti-tTG autoantibodies of 12 patients with CD led to a dose dependent reduction of tTG activity, compared to control immunoglobulins (n = 6). However, the remaining activity was sufficient for cross linking of cadaverine into gliadin, and enzymatic tTG activity was only blocked completely by high concentrations of a monoclonal antibody, which is directed to the active centre of tTG. Conclusions: Despite a partial inhibitory effect of isolated anti-tTG autoantibodies from patients with CD, residual enzymatic activity remains sufficiently high to cast doubt on their in vivo relevance.

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Anti-tissue transglutaminase antibodies from coeliac patients inhibit transglutaminase activity both in vitro and in situ

Cited by 112 publications

References 33 publications

Identification of Aldolase as a Target Antigen in Alzheimer’s Disease

Identification of Aldolase as a Target Antigen in Alzheimer’s Disease

Proteomics Identification of Acyl-acceptor and Acyl-donor Substrates for Transglutaminase in a Human Intestinal Epithelial Cell Line

Autoantibodies of patients with coeliac disease are insufficient to block tissue transglutaminase activity

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