| 1. |
- Agardh, Daniel, et al.
(författare)
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Coeliac disease-specific tissue transglutaminase autoantibodies are associated with osteoporosis and related fractures in middle-aged women
- 2009
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 44:5, s. 571-578
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To investigate whether the serological marker for coeliac disease, tissue transglutaminase autoantibody (tTGAb), is associated with decreased bone mass density (BMD) and increased frequency of fractures in middle-aged women screened for osteoporosis. Material and methods. The study comprised 6480 women (mean age 56 years, range 50-64) who answered a number of questionnaires and who underwent dual X-ray absorptiometry of the wrist bone. Serum samples were analysed for tTGAb using radioligand binding assays. A tTGAb level of 4 U/ml was used to determine a positive value and a level of 17 U/ml was used as an alternative discrimination of high levels. Results. A tTGAb level 4 U/ml was found among 90/6480 (1.4%) women and correlated with lower BMD (multiple linear regression coefficient -382.1; 95% CI = - 673.6-90.7, p=0.011) and with fracture frequency (r=0.18, p=0.023). The 59 women with tTGAb levels 17 U/ml had a lower BMD (0.410.08 g/cm2 versus 0.440.08 g/cm2, p=0.001) and a lower T-score (-1.401.28 versus -0.901.40, p=0.003) as well as a higher prevalence of osteoporosis (13.4% versus 6.5%, p=0.008) compared with the remaining 6421 women with tTGAb levels 17 U/ml. Furthermore, fracture frequency was more pronounced in women with tTGAb levels 17 U/ml, among whom 19/59 (32.2%) had fractures during the study period compared with 1204/6421 (18.8%) among women with tTGAb levels 17 U/ml (p=0.009). Conclusions. High levels of tTGAb indicating coeliac disease are associated with lower BMD and higher fracture frequency in women between 50 and 64 years of age. Osteometry is therefore warranted in middle-aged women detected with tTGAb.
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| 2. |
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| 3. |
- Agardh, Daniel, et al.
(författare)
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Autoantibodies Against Soluble and Immobilized Human Recombinant Tissue Transglutaminase in Children with Celiac Disease.
- 2005
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Ingår i: Journal of Pediatric Gastroenterology and Nutrition - Jpgn. - : Ovid Technologies (Wolters Kluwer Health). - 1536-4801 .- 0277-2116. ; 41:3, s. 322-327
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The conformation of tissue transglutaminase might influence the performance of immunoassays to detect autoantibodies from patients with celiac disease. The present study investigated how the exposure of tissue transglutaminase kept in a liquid phase and fixed to a solid support affected the binding of immunoglobulin (Ig)A and IgG autoantibodies in children with untreated and treated celiac disease. Methods: Included were 73 untreated celiac disease children, 50 controls and 80 children with treated celiac disease. IgA and IgG antitissue transglutaminase were measured with solid phase enzyme-linked immunoassay (ELISA) and liquid phase radioligand binding assays. For IgG antitissue transglutaminase detection with radioligand binding assays antihuman IgG and protein A were used. IgA endomysial autoantibodies were measured by indirect immunofluorescence. Results: Both ELISA and radioligand binding assays detected IgA antitissue transglutaminase in 65 of 73 untreated celiac disease children and in 2 of 50 controls. One additional control child was detected with radioligand binding assays. Endomysial autoantibodies were present in 62 of 73 celiac disease children and in 2 of 50 controls. IgG antitissue transglutaminase was detected with both ELISA and radioligand binding assays in 40 of 73 untreated celiac disease children and in 2 of 50 controls. Radioligand binding assays using protein A detected 20 of 73 additional untreated celiac disease children and one control child with increased IgG antitissue transglutaminase. In treated celiac disease children, 21 of 80 were IgA antitissue transglutaminase positive with radioligand binding assays, 3 of 80 with ELISA, whereas none had endomysial autoantibodies. Conclusions: No qualitative differences between radioligand binding assays and ELISA in IgA or IgG antitissue transglutaminase binding from untreated celiac disease children was demonstrated. However, discrepancies in the binding of IgA antitissue transglutaminase from a subgroup of treated celiac disease children indicated that alterations of tissue transglutaminase might occur on fixation of the antigen. Protein A used for radioligand binding assays seemed not to assess IgG autoantibodies exclusively. IgA antitissue transglutaminase detection in screening of childhood celiac disease can be performed either by ELISA or radioligand binding assays because the two assays are interchangeable.
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| 4. |
- Agardh, Daniel, et al.
(författare)
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Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease.
- 2005
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Ingår i: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981. ; 358:1-2, s. 95-103
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Tidskriftsartikel (refereegranskat)abstract
- Background Conflicting data have been published concerning the effect of calcium on binding of autoantibodies to tissue transglutaminase (tTG) in celiac disease (CD). Methods IgA-tTG and IgG-tTG were measured with radioligand binding assays (RBA) using human recombinant (hr) 35S-tTG produced in lysate of rabbit reticulocytes and with guinea pig (gp) tTG ELISA in 51 CD children (median: 5.7 years) and 35 controls (median: 2.2 years). Assays were performed with and without calcium. Results In hr-tTG RBA, IgA-tTG levels remained unchanged after calcium detecting 50/51 CD children and 1/35 controls (p < 0.0001). IgG-tTG levels decreased with calcium (p < 0.0001) in CD children and detected 48/51 with and 49/51 without calcium as compared to 1/35 controls (p < 0.0001). In gp-tTG ELISA, levels increased with calcium (p < 0.0001) making it possible to detect an additional three to a total of 50/51 with IgA-tTG and 13 to 39/51 CD children with IgG-tTG compared to 4/35 and 8/35 controls (respectively, p < 0.0001). Rabbit reticulocytes displayed calcium-dependent tTG activity. Conclusions Calcium increased binding of IgA-tTG and IgG-tTG in the ELISA test. The reverse effect observed in RBA may be explained by competitive binding between calcium activated native rabbit reticulocyte tTG and hr 35S-tTG. tTG autoantibody assays may need taking calcium into account for accurate diagnostic sensitivity and specificity for CD.
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| 5. |
- Agardh, Daniel, et al.
(författare)
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Reduction of tissue transglutaminase autoantibody levels by gluten-free diet is associated with changes in subsets of peripheral blood lymphocytes in children with newly diagnosed coeliac disease.
- 2006
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Ingår i: Clinical and Experimental Immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 144:1, s. 67-75
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Tidskriftsartikel (refereegranskat)abstract
- Tissue transglutaminase (tTG) autoantibodies decline after gluten-free diet in patients with coeliac disease. We tested the hypothesis that gluten-free diet-induced change in tTG autoantibody levels affects subsets of peripheral blood lymphocytes. Peripheral blood was obtained from 20 children with biopsy-proven active coeliac disease. Gluten-free diet was initiated and the children examined again after three and six months. tTG autoantibodies were measured in radioligand binding assays and lymphocyte subsets by flow cytometry. IgA-tTG levels at diagnosis, 2204 U/ml (median, range 113–24990), were reduced over six months to 76 U/ml (median, range 1–1261) (P < 0·001). At six months, 12/20 (60%) children had reduced their IgA-tTG levels to < 100 U/ml and these children showed a decrease in B cells (mean change −3·8%, P = 0·014), CD4+ T cells (mean −4·32%, P = 0·011) and CD4+ T cells expressing CD25high (mean change −0·62%, P = 0·036). In contrast, the CD4+CD25highCCR4+ T cell population increased during the same period (mean change 11·5%, P = 0·0036). The decline in IgA-tTG levels correlated to the decrease in B cells (r = 0·56, P = 0·01), CD4+ T cells (r = 0·66, P = 0·004) as well as CD4+CD25high T cells (r = 0·59, P = 0·01). A negative correlation was found between the decline in IgA-tTG and CD4+CD25high T cells expressing CD45RO (r = –0·49, P = 0·03) and CCR4 (r = –0·54, P = 0·01). This is the first observational study on the effect of gluten-free diet on concurrent changes of tTG autoantibodies and specific peripheral blood lymphocyte subsets. Our data suggest that flow cytometry may be a useful complement to tTG autoantibodies when studying the effects of gluten-free diet in children with coeliac disease.
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| 6. |
- Agardh, Daniel
(författare)
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Tissue transglutaminase autoantibodies in childhood celiac disease
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Celiac disease is a prevalent small bowel disease in children caused by permanent intolerance against gliadin, which is the alcohol-soluble fraction of the cereal protein gluten in wheat, rye and barley. Celiac disease is characterized by an inflammatory infiltrate of CD4+ T lymphocytes in the intestinal mucosa leading to damage of villous structure and loss of absorptive surface. As a consequence, gastrointestinal symptoms and signs of malnutrition often occur in children. The exclusion of gluten from the diet results in healing of the intestinal mucosa. Celiac disease is also strongly associated with tissue transglutaminase (tTG) autoantibodies that are considered to be markers for the disease. Moreover, levels of tTG autoantibodies decline after gluten withdrawal, which enables objective evaluation of how patients respond to treatment with gluten-free diet. The use of serological markers for diagnostic purposes in celiac disease will most likely increase as screenings of large populations are performed. It is therefore important to test the current methods for autoantibody detection. The aim of the present thesis was to evaluate radioimmunoassays for the assessment of tTG autoantibodies in children with celiac disease. In Study I, the diagnostic sensitivity and specificity were determined for autoantibodies against human recombinant tTG with liquid phase radioligand binding immunoassays. It was shown that the diagnostic sensitivities for IgA-tTG and IgG-tTG were 85% and 84%, respectively, and the specificity for both isotypes was 94%. The sensitivities were lower compared with previous studies based on similar radioimmunoassays and mainly explained by the inclusion of children diagnosed at two years of age or younger. In Study II, it was examined how human recombinant tTG affected the binding of tTG autoantibodies in liquid phase compared with solid phase immunoassays. We hypothesized that epitopes may be hidden for autoantibodies in the solid phase, but results showed high concordance for IgA-tTG in children with untreated celiac disease. However, the specific binding of IgG-tTG was significantly reduced compared with the two IgA-assays. In contrast, using protein A for binding IgG-tTG in the radioligand binding assays nearly displayed as high diagnostic accuracy as IgA-tTG. In Study III, the effect of gluten-free diet on tTG autoantibody levels and subsets of peripheral blood lymphocytes by flow cytometry were investigated in children with newly diagnosed celiac disease. It was observed that the decline in tTG autoantibody levels subsequent to gluten-free diet was associated with concomitant changes in B cells and a subset of CD4+ regulatory T cells expressing the markers CD25 and CCR4, indicating that flow cytometry might be a useful complement to tTG autoantibodies in monitoring of the disease activity in celiac disease. In Study IV, tTG autoantibodies and endomysial autoantibodies were measured in a screening for celiac disease performed on normal 3-year old children. The outcome of the study diagnosed 0.5% of children with previously unrecognized celiac disease. Although the study revealed a high number of children with transient autoantibodies, the combination of IgA-tTG and IgG-tTG seemed to better predict persistent autoantibodies and a pathological biopsy than any of the autoantibodies alone. In conlusion, this thesis adds new aspects in terms of how tTG autoantibodies can be used as serological markers in children investigated for celiac disease. It is proposed that both IgA-tTG and IgG-tTG are analyzed with radioligand binding assays in children screened for celiac disease with the primary goal to develop a standardized immunoassay in near future.
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| 7. |
- Carlsson, Annelie, et al.
(författare)
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Prevalence of celiac disease : Before and after a national change in feeding recommendations
- 2006
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 41:5, s. 553-558
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Tidskriftsartikel (refereegranskat)abstract
- Objective. A national change in infant feeding recommendations was proposed in 1996 in Sweden: a slow introduction to gluten during weaning was stressed, the recommendation being introduction at 4 instead of 6 months of age. The aim of the present study was to compare the prevalence of celiac disease in healthy young children born before and after the new feeding recommendations in 1996. Material and methods. Sera from 679 children at a median age of 2.9 years (range 2.5-4.2 years) born between January 1996 and November 1997 were investigated with IgA-antigliadin antibodies (AGA) and IgA-endomysial autoantibodies (EMA) and compared with 690 age-matched children born between July 1992 and June 1993. Children with a positive test for EMA and AGA or EMA only were re-tested, and if positive at follow up, investigated with intestinal biopsy. Results. At baseline, 2.2% (15/679) children were positive for EMA and another 0.6% (4/679) for both EMA and AGA. One child refused to be re-tested and eight children were still EMA positive at follow-up. Intestinal biopsy was performed in seven children (one declined biopsy), of whom three showed total villous atrophy. Two children with EMA titers 1:640, respectively, refused further participation in the study, but were strongly suspected to have celiac disease. In total, 0.7% (5/679) (95% confidence interval (CI) = 0.1-1.4%) were considered to have celiac disease compared with 1.3% (9/690) (95% CI = 0.4-2.2%) in the control group (p = 0.4217). In addition, 0.3% of the children were diagnosed with symptomatic celiac disease compared with 0.7% in controls (p = 0.0134). Conclusions. The prevalence of symptomatic celiac disease declined after the infant dietary recommendations were introduced in 1996, but we could not find any difference in undiagnosed celiac disease between the screened children born before and those born after 1996. © 2006 Taylor & Francis.
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| 8. |
- Dahlbom, Ingrid, et al.
(författare)
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Protein A and protein G ELISA for the detection of IgG autoantibodies against tissue transglutaminase in childhood celiac disease
- 2008
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Ingår i: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981 .- 1873-3492. ; 395:1-2, s. 72-6
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate if the detection of celiac disease (CD) in children was improved by using alternative conjugates for assessment of tissue transglutaminase (tTG) autoantibodies. Methods: Serum samples from 108 biopsy confirmed CD children and 42 control subjects were investigated for the presence of autoantibodies with tTG coated microplates using protein A (PA), protein G (PG), anti-IgG, or anti-IgA as conjugates. Results: Of the 108 CD children, 86 (80%) were IgG-tTG positive, 91 (84%) were positive with the PA-conjugate, 94 (87%) were positive with the PG-conjugate, and 103 (95%) were IgA-tTG positive. Among the 42 controls. 4 (10%) were IgG-tTG positive, 5 (12%) were positive with both the PA- and PG conjugates. whereas 3 (7%) were IgA-tTG positive. Compared with IgG-tTG the concordance was 93% for PA and 95% for PG, with a positive correlation between antibody levels (r=0.967 and r=0.975. p< ;0.0001). All but one CD child were found positive by combining IgG-tTG and IgA-tTG detection. Conclusions: The sensitivity of IgG-tTG detection with ELISA increased by protein A or protein G conjugates, whereas the specificity was reduced as compared with anti-IgG conjugate. The combined measurement of IgA-tTG and IgG-tTG still seems to be the optimal procedure when screening children for CD.
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| 9. |
- Li, Marcella, et al.
(författare)
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A Report on the International Transglutaminase Autoantibody Workshop for Celiac Disease
- 2009
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Ingår i: American Journal of Gastroenterology. - : Ovid Technologies (Wolters Kluwer Health). - 1572-0241 .- 0002-9270. ; 104:1, s. 154-163
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Measurement of transglutaminase autoantibodies (TGAA) is considered to be the most efficient single serologic test for celiac disease (CD) by the American Gastroenterological Association Institute. We hypothesized that a large international collaborative effort toward improving and standardizing TGAA measurement is both feasible and necessary. The primary aim of this workshop is to compare TGAA assays among various research and clinical laboratories and examine assay concordance and improve (and eventually standardize) the TGAA assay. METHODS: A total of 20 laboratories (5 commercial laboratories, 15 research and clinical laboratories) participated that included enzyme-linked immunosorbent assay (ELISA) and radiobinding assays. A total of 150 serum samples were distributed to each laboratory, with each laboratory receiving an equal aliquot that was coded and blinded, composed of 100 healthy control sera and 50 CD sera. RESULTS: Laboratory sensitivity ranged from 69% to 93% and specificity ranged from 96% to 100%. By receiver operator characteristic analysis, the area under the curve (C index) ranged from 0.9488 to 0.9904. When analyzing for linear correlation, r-squared was as high as 0.8882 but as low as 0.4244 for the celiac samples between different laboratories performing ELISA. CONCLUSIONS: This transglutaminase autoantibody workshop allows for larger-scale international participation for the purposes of improving and eventually standardizing the TGAA assay with subsequent workshops.
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| 10. |
- Rewers, Marian, et al.
(författare)
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The Environmental Determinants of Diabetes in the Young (TEDDY) Study
- 2008
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923 .- 1749-6632. ; 1150, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- The etiology of type 1 diabetes (T1D) remains unknown, but a growing body of evidence points to infectious agents and/or components of early childhood diet. The National Institutes of Health has established the TEDDY Study consortium of six clinical centers in the United States and Europe and a data coordinating center to identify environmental factors predisposing to, or protective against, islet autoimmunity and T1D. From 2004-2009, TEDDY will screen more than 360,000 newborns from both the general population and families already affected by T1D to identify an estimated 17,804 children with high-risk HLA-DR,DQ genotypes. Of those, 7,801 (788 first-degree relatives and 7,013 newborns with no family history of T1D) will be enrolled in prospective follow-up beginning before the age of 4.5 months. As of May 2008, TEDDY has screened more than 250,000 newborns and enrolled nearly 5,000 infants--approximately 70% of the final cohort. Participants are seen every 3 months up to 4 years of age, with subsequent visits every 6 months until the subject is 15 years of age. Blood samples are collected at each visit for detection of candidate infectious agents and nutritional biomarkers; monthly stool samples are collected for infectious agents. These samples are saved in a central repository. Primary endpoints include (1) appearance of one or more islet autoantibodies (to insulin, GAD65 or IA-2) confirmed at two consecutive visits; (2) development of T1D. By age 15, an estimated 800 children will develop islet autoimmunity and 400 will progress to T1D; 67 and 27 children have already reached these endpoints.
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