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Peptide Immunotherapy for Type 1 Diabetes is Fast Becoming a Reality
Jefferson Adams posted an article in Diabetes and Celiac Disease
Celiac.com 10/29/2018 - Researchers Emma L. Smith with UCB Pharma Ltd., Slough, United Kingdom, and Mark Peakman from the Department of Immunobiology, King’s College London, London, United Kingdom recently set out to catalog clinical advances in peptide immunotherapy for Type 1 diabetes. Autoimmune and allergic diseases occur when a person’s body has an incorrect immune response to an antigen from the person’s own body, or to an innocuous antigen from outside the body. This triggers a pathogenic T-cell response which causes damage to certain tissues and organs. In Type 1 diabetes, this process results in the destruction of the insulin-secreting β cells, which leads to permanent need for recombinant insulin to make up for the loss. The best way to restore immune homeostasis and prevent further tissue damage is to reduce or cease the pathogenic T-cell response by using antigen-specific peptide immunotherapy. Smith and Peakman found that recent clinical advances with peptide therapy approaches in both Type 1 diabetes and other diseases are beginning to show encouraging results. New treatments that target peptides specific to certain cell types are also moving from the development stages into clinical use. Drug developers still face numerous hurdles in reaching full clinical use, including determining optimal dose and dosing frequency, but peptide immunotherapy for Type 1 diabetes is clearly becoming a very active field of drug development. Read their full report: Front Immunol. 2018; 9: 392.Published online 2018 Feb 28. doi: 10.3389/fimmu.2018.00392PMCID: PMC5836708PMID: 29541078 -
Celiac.com 08/20/2015 - Celiac disease is frequently mis-diagnosed. Even when patients received endoscopy, celiac disease is often missed or not detected. A team of researchers recently assessed the accuracy of finger prick-based point-of-care tests in the detection of celiac disease, and developed an algorithm for diagnosis. The research team included PD Mooney, SH Wong, AJ Johnston, M Kurien, A Avgerinos, and DS Sanders. They are variously affiliated with the Royal Hallamshire Hospital, Sheffield, United Kingdom and the University of Sheffield, Sheffield, United Kingdom. Their team conducted a prospective study of two groups of celiac disease patients evaluated at the Royal Hallamshire Hospital in Sheffield UK from March 2013 through February 2014. In group one, the team evaluated 55 patients at high risk for celiac disease, and who tested positive for endomysial antibody, using the Biocard test (BHR Pharmaceuticals, Nuneaton, UK) and the Celiac Quick Test (Biohit Healthcare UK, Ellesmere Port, UK), which measure antibodies to tissue transglutaminase (anti-tTG), and the Simtomax test (Tillotts Pharma, Rheinfelden, Switzerland), which measures deamidated gliadin peptide antibodies (DGP). Group 2 included 508 consecutive patients who received an endoscopy for any reason, received the DGP test, and also were evaluated using a diagnostic algorithm that incorporated results from the DGP test and data on symptoms. For both groups, point-of-care tests were administered at the time of endoscopy, and the results compared against results from histologic analyses of duodenal biopsy specimens from all patients. In group 1, the DGP test identified patients with celiac disease with 94.4% sensitivity, the Celiac Quick Test identified patients with 77.8% sensitivity (P = .03 vs the DGP test), while the Biocard test identified patients with 72.2% sensitivity (P = .008 vs the DGP test). In group 2, the DGP test identified patients with celiac disease with 92.7% sensitivity (95% confidence interval, 83.0-97.3), 85.2% specificity (95% confidence interval, 81.5-88.3), a positive predictive value of 49.2% (95% confidence interval, 40.3-58.2), and a negative predictive value of 98.7% (95% confidence interval, 96.8-99.5). Measurement of serum anti-tTG identified patients with celiac disease with 91.2% sensitivity (95% confidence interval, 81.1-96.4), 87.5% specificity (95% confidence interval, 84.0-90.4), a positive predictive value of 53.0% (95% confidence interval, 43.6-62.2), and a negative predictive value of 98.5% (95% confidence interval, 96.5-99.4). The algorithm identified patients with celiac disease with 98.5% sensitivity, and has the potential to reduce duodenal biopsies by 35%. In this prospective study, the test for DGP identified celiac patients with comparable sensitivity and specificity as standard serologic analysis of anti-tTG. Conducting the DGP test before endoscopy might increase the accuracy of the diagnosis of celiac disease. These results look promising, but further study is needed, in lower-prevalence populations, to more accurately determine the potential benefits of the DGP test in celiac screening. Source: Clin Gastroenterol Hepatol. 2015 Jul;13(7):1278-1284.e1. doi: 10.1016/j.cgh.2015.01.010. Epub 2015 Jan 26.
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Can Testing for Antibodies to Deamidated Gliadin Peptide Allow Earlier Celiac Disease Diagnosis in Children?
Jefferson Adams posted an article in Celiac Disease & Gluten Intolerance Research
Celiac.com 01/29/2015 - Testing for tissue transglutaminase antibodies (TGA) is currently a common part of attempting to diagnose celiac disease. A research team wanted to find out if determination of antibodies to synthetic deamidatedgliadin peptides (anti-DGP) might work as an alternative or complement to TGA testing. To find out, the team assessed the performance of a time-resolved immunofluorometry (TR-IFMA) based anti-DGP assay in the diagnosis of celiac disease in children, and also retrospectively analyzed the appearance of anti-DGP antibodies before TGA seroconversion. The research team included A. Lammi, P. Arikoski, S. Simell, T. Kinnunen, V. Simell, S. Paavanen-Huhtala, A. Hinkkanen, R. Veijola, M. Knip, J. Toppari, O. Vaarala, O. Simell, and J. Ilonen. They are variously affiliated with the Department of Clinical Microbiology and the A.I. Virtanen Institute for Molecular Sciences at the University of Eastern Finland in Kuopio, Finland, the Department of Pediatrics at Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland, the Department of Pediatrics at the University of Oulu and Oulu University Hospital in Oulu, Finland, the Children's Hospital, and the Institute of Clinical Medicine at the University of Helsinki in Helsinki, Finland, the Folkhälsan Research Center in Helsinki, Finland, the Department of Pediatrics at Tampere University Hospital in Tampere, Finland, the Immunogenetics Laboratory, and the Department of Physiology at the University of Turku, and with the Department of Pediatrics and Adolescent Medicine at the University of Turku and Turku University Hospital in Turku, Finland. For their study, the team assessed 92 children with biopsy-confirmed celiac disease. The team took blood samples at the time of, or just prior to, clinical diagnosis. The team also assessed a control group of 82 TGA-negative children who were positive for HLA-DQ2 or -DQ8. Based on receiver operating characteristics (ROC) curves, they found that the optimal cut-off value for IgA anti-DGP positivity was 153 arbitrary units (AU) with a sensitivity of 92.4% and specificity of 97.6%, while the optimal cut-off value for IgG anti-DGP 119 AU, with a sensitivity of 97.8% and specificity of 97.6%. They found that all 92 children with celiac disease tested positive for either IgA or IgG anti-DGP at the time of diagnosis. Blood results from 48 children with celiac disease, analyzed retrospectively before the diagnosis, showed that anti-DGP antibodies preceded TGA positivity in 35 of 48 celiac disease children and appeared an average of one year earlier. From these results, the TR-IFMA test for detecting anti-DGP antibodies shows high sensitivity and specificity for celiac disease in children. For most of the patients, anti-DGP seropositivity preceded TGA positivity, which means that monitoring anti-DGP antibodies frequently in genetically susceptible children might allow doctors to spot celiac disease earlier than allowed by current tests. Source: J Pediatr Gastroenterol Nutr. 2014 Dec 16. -
Durum Wheat Peptide Could Lead To Celiac Disease Treatment
Roy Jamron posted an article in Celiac Disease & Gluten Intolerance Research
Celiac.com 02/10/2008 - Researchers have found a 10mer durum wheat peptide capable of shifting a Th1 gluten-intolerant T cell response to a Th2 gluten-tolerant T cell response in intestinal T cell cultures derived from celiac disease children and incubated with deamidated gliadin peptides. Durum wheat peptides could potentially treat celiac disease by causing celiac disease associated T cells to react tolerantly to gluten. In the study, incubation of the T cell cultures with deamidated gliadin peptides resulted in a significant increase in T cell proliferation and interferon-gamma release. Simultaneous exposure to duram wheat peptides totally abolished the cell proliferation and cytokine release while maintaining an elevated release of interleukin-10 (IL-10). The workings of the immune system are too complex to discuss here in detail. Basically when a "pre-helper" CD4-type T cell is presented with an epitope from an antigen (gliadin), the T cell becomes activated and responds to the stimulus by becoming either a type 1 or type 2 helper T cell which in turn releases different subsets of cytokines. The Th1 path promotes mucosal tissue destruction in celiac disease while the Th2 path initiates proliferation of gluten and tTGase antibodies. Th1 and Th2 cytokines each have properties which act in a feedback loop to suppress, limit, and regulate each other's cytokine secretions, i.e. Th1 cytokines suppress Th2 cytokine secretion and vice vesa. Overactivity of either a Th1 or a Th2 response can result in an autoimmune condition. Researchers theorize that balancing Th1/Th2 response can ameliorate and control symptoms and disease progression in at least some autoimmune diseases. Th1 response includes release of the cytokine interferon-gamma which differentiates and activates macrophages. Th2 response can include the release of IL-10, a cytokine which suppresses inflammation and promotes antigen tolerance. Various molecules have been demonstrated to shift Th1/Th2 response in various autoimmune disorders. In the durum wheat study, the presence of the durum wheat peptide in the gliadin peptide incubated celiac intestinal T cell culture increased Th2 IL-10 release and stopped T cell proliferation and Th1 interferon-gamma release. Hence, this durum wheat peptide may be useful as a celiac disease therapy. How effective this treatment may be is unknown at this time. Below is an example of sodium benzoate being used to shift Th1 to Th2 response in a mouse model of multiple sclerosis which improved symptoms and disease progression when fed to the mice orally. This suggests that the durum wheat peptide could potentially treat celiac disease by simply being administered as an oral supplement. However, if a probiotic bacteria could be genetically engineered to continuously secrete a form of this durum wheat peptide in the gut, this could result in essentially a "cure" for celiac disease if the durum wheat peptide proves effective. ---------- Am J Clin Nutr. 2008 Feb;87(2):415-23. A 10-residue peptide from durum wheat promotes a shift from a Th1-type response toward a Th2-type response in celiac disease. Silano M, Di Benedetto R, Maialetti F, De Vincenzi A, Calcaterra R, Trecca A, De Vincenzi M. Division of Food Science, Human Nutrition and Health, Istituto Superiore di Sanita, Rome, Italy. http://www.ajcn.org/cgi/content/abstract/87/2/415 ---------- J Immunol. 2007 Jul 1;179(1):275-83. Sodium benzoate, a food additive and a metabolite of cinnamon, modifies T cells at multiple steps and inhibits adoptive transfer of experimental allergic encephalomyelitis. Brahmachari S, Pahan K. Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street, Chicago, IL 60612, USA. http://www.jimmunol.org/cgi/content/abstract/179/1/275 * * * -
New Gliadin Peptide Plays a Key Role in Celiac Disease
Jefferson Adams posted an article in Celiac Disease & Gluten Intolerance Research
Celiac.com 03/09/2011 - A team of researchers recently identified a novel immunomodulatory gliadin peptide that triggers interleukin-8 release in a chemokine receptor CXCR3-dependent manner only in patients with celiac disease. The research team included Karen M. Lammers; Sunaina Khandelwal; Fatima Chaudhry; Debby Kryszak; Elaine L. Puppa; Vincenzo Casolaro; and Alessio Fasano. The same research team had previously reported that the chemokine receptor CXCR3 serves as a receptor for specific gliadin peptides that trigger zonulin release and increase in intestinal permeability. This mechanism plays an important role in the adverse immune reaction to gluten-containing grains that is central to the classic celiac disease response. To examine the role of CXCR3 in the immune response to gliadin, the researchers incubated peripheral blood mononuclear cells of both celiac patients and healthy controls with either pepsin-trypsin-digested gliadin or 11 α-gliadin synthetic peptides in the presence or absence of a blocking anti-CXCR3 monoclonal antibody. The team then analyzed supernatants for interleukin-6 (IL-6), IL-8, IL-10, IL-13, IP-10 (CXCL10), tumour necrosis factor-α and interferon-γ. Gliadin triggered cytokine production regardless of clinical condition. However, only small number of individuals showed IL-8 production. In those individuals, cells originating from white blood cells were the main source of IL-8 production. The team used one of a comprehensive panel of synthetic α-gliadin peptides to reproduce the induction of IL-8. They were able to cease the process by blocking CXCR3 before stimulation with either gliadin or this peptide in the celiac group, but not in the control group. This suggests that gliadin-induced IL-8 production is CXCR3-dependent only in people with celiac disease. Source: Immunology, Volume 132, Number 3, March 2011 , pp. 432-440(9) -
Celiac.com 03/25/2010 - A team of researchers recently set out to compare the diagnostic performance of IgG anti-deamidated gliadin peptide antibody assays against IgA anti-tTG in celiac disease. The team included P. Vermeersch, K. Geboes, G. Mariën, I. Hoffman, M. Hiele, X. Bossuyt, all associated with the department of Laboratory Medicine, Immunology of University Hospitals at the Catholic University of Leuven, Belgium. Using IgG anti-deamidated gliadin peptide antibody assays to test for celiac disease is more sensitive and more specific for celiac disease than detection of IgG antibodies against native gliadin. The team compared assessed the technical performance and accuracy (sensitivity and specificity) of commercial IgG anti-DGP assays from Euroimmun, Inova, Phadia and The Binding Site against other serologic assays for celiac disease, such as 3IgA and 2IgG anti-tTG assays, 1IgA and 1IgG anti-gliadin assay, 1IgA anti-DGP assay. For the study, they tested 86 patients with clinically proven celiac disease and 741 healthy control subjects. Technical performance of IgG anti-DGP assays as gauged by linearity, interference and imprecision, was within acceptable levels. IgG anti-DGP assay sensitivity ranged between 76.7% and 83.7% at the manufacturer's recommended cut-off, and between 74.4% and 84.9% at a cut-off that corresponded to a 98% specificity level. Specificity ranged between 97.3% and 99.3%. The diagnostic accuracy of the IgG anti-DGP assays was comparable to the diagnostic accuracy of the IgA anti-tTG assays. IgG anti-DGP assays showed significantly better than sensitivity than the IgG anti-tTG assays (p<0.05) and and significantly better specificity than IgA and IgG anti-gliadin assays (p<0.05). The four IgG anti-DGP assays all performed within acceptable limits, and diagnosed celiac disease with comparable accuracy as did the three IgA anti-tTG assays. Source: Clin Chim Acta. 2010 Feb 19.
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Designing new High Affinity Peptide Ligands for HLA-DQ2 Using a Positional Scanning Peptide Library
Jefferson Adams posted an article in Celiac Disease & Gluten Intolerance Research
A team of researchers recently to examine the design of new high affinity peptide ligands for HLA-DQ2 using a positional scanning peptide library. The research team included U. Jüse, Y. van de Wal, F. Koning, L. M. Sollid, B. Fleckenstein with the Centre for Immune Regulation, Institute of Immunology, Oslo University Hospital-Rikshospitalet, Oslo, Norway. HLA-DQ2 (DQA1*0501/DQB1*0201) is associated with several immune disorders including celiac disease, which results from an inappropriate T-cell response to gluten. Researchers hope that interference with peptide presentation by HLA-DQ2, perhaps through the use of of peptide blockers, might lead to new treatment strategy for such HLA associated disorders. For such strategies to work, it will be necessary to identify ligands that bind much better to HLA-DQ2 than the disease related epitopes. The team used a positional scanning nonapeptide library to determine the optimal amino acids for each position of the HLA-DQ2 binding frame. By combining the optimal residues in each position, the team was able to design high affinity binders to HLA-DQ2. Interestingly, the decapeptide with highest affinity was composed of the most favorable residues in each position. This sequence bound 50-fold better than the immunodominant gluten epitope DQ2-alpha-I-gliadin what makes it an interesting lead compound for the development of blockers. The correlation between measured and predicted affinities was poorer for some natural HLA-DQ2 ligands, but notably these peptides did not have optimal amino acids at all positions. The team's method offers a straightforward approach for developing high affinity binders to HLA class II molecules. Source: Hum Immunol. 2010 Jan 24. -
Using Non-Inflammatory Gluten Peptide Analogs as Biomarkers for Celiac Disease
Jefferson Adams posted an article in Celiac Disease Diagnosis, Testing & Treatment
Celiac.com 09/30/2009 - Are non-inflammatory gluten peptide analogs effective as biomarkers for celiac disease? Recent research indicates that they just might represent an effective new tool in the management of celiac disease. In the August 28th issue of Chemical Biology, a team of researchers from Stanford University's Department of Biochemistry issues a call for new tools to manage celiac disease, a lifelong immune disease of the small intestine. Non-inflammatory gluten peptide analogs may be one of the important new tools in that effort. The research team is made up of M. T. Bethune, M. Crespo-Bosque, E. Bergseng, K. Mazumdar, L. Doyle, K. Sestak, L. M. Sollid, and C. Khosla. They note that current drug trials are sparking a researchers to seek non-invasive biomarkers of gluten-induced intestinal change. They note also that they have synthesized and characterized non-inflammatory gluten peptide analogs in which Asn or His replace key Gln residues. As with their pro-inflammatory associates, these genetic markers resist gastrointestinal proteases, are susceptible to glutenases, and permeable across enterocyte barriers. In contrast with gluten peptides, however, the markers are not commonly acknowledged by transglutaminase, HLA-DQ2, or disease-specific T cells. In vitro and animal tests prove that the biomarkers can reveal shifts in intestinal permeability as well as glutenase-catalyzed gastric detoxification of gluten. As a result, they call for controlled clinical studies to assess the use of these peptides as markers for abnormal intestinal permeability in celiac patients and for the effectiveness of glutenase in clinical trial and treatment of celiac disease. Chem Biol. 2009 Aug 28;16(8):868-81. -
Gluten Peptide Research Advancing Immunotherapy for Celiac Disease
Jefferson Adams posted an article in Celiac Disease & Gluten Intolerance Research
Celiac.com 04/24/2009 - Currently, one of the more promising areas of celiac disease research looks to be in peptide-based therapies. One of the keys to creating an effective peptide-based therapy for celiac disease lies in identifying the gluten peptides that trigger intestinal T cell responses when people with celiac disease consume wheat, rye, or barley. A team of Italian researchers recently set out to do just that. The team was made up of A. Camarca, R.P. Anderson, G. Mamone, O. Fierro , A. Facchiano, S. Costantini, D. Zanzi, J. Sidney, S. Auricchio, A. Sette, R. Troncone, and C. Gianfrani. Their efforts were supported by the Institute of Food Sciences-National Research Council, Avellino, Italy. Their research carries strong implications for a peptide-based therapy in celiac disease. Presently, several gluten peptides are known to be active in celiac disease. The identification of additional gluten peptides eliciting intestinal T cell responses is critical for designing a successful peptide-based immunotherapy for celiac disease. In their study, the research team assessed the recognition profile of gluten immunogenic peptides in adult HLA-DQ2(+) celiac patients. They did so by creating several lines of polyclonal, gliadin-reactive T cells from jejunal mucosa. They then tested for both proliferation and IFN-gamma production in reaction to 21 peptides from wheat glutenins and alpha-, gamma-, and omega-gliadins. They then conducted a magnitude analysis of the IFN-gamma responses to determine the spectrum of individual peptide activity, and to rank them accordingly. Notably, 12 of the 14 patients responded to a different array of peptides. All alpha-gliadin stimulatory peptides mapped the 57-89 N-terminal region, thus affirming the importance of the known polyepitope 33-mer, although only 50% of subjects recognized 33-mer. By contrast, 11 of 14 celiac subjects, nearly 80%, responded to gamma-gliadin peptides. A 17-mer variant of 33-mer, QLQPFPQPQLPYPQPQP, posessing only a single copy of DQ2-alpha-I and DQ2-alpha-II epitopes, displayed the same potency as 33-mer in triggering intestinal T cell responses. One particular peptide from omega-gliadin, QPQQPFPQPQQPFPWQP, though structurally related to the alpha-gliadin 17-mer, is a separate epitope and activated in 5 out of 14 subjects. The team's data reveal that intestinal T cells respond to a wide array of peptides, and that this heterogeneity emphasizes the relevance of gamma- and omega-gliadin peptides in celiac disease pathogenesis. Their findings indicate that, in DQ2(+) celiac patients, the most active gluten peptides are alpha-gliadin (57-73), gamma-gliadin (139-153), and omega-gliadin (102-118). J Immunol. 2009 Apr 1;182(7):4158-66. -
Peptide in Durum Wheat May Protect Against Effects of Celiac Disease
Jefferson Adams posted an article in Celiac Disease & Gluten Intolerance Research
Celiac.com 05/08/2007 - One of the strategies for developing alternative therapies for treating celiac disease centers on the identification of antagonist peptides that might inhibit the abnormal immune response caused by gliadin peptides in celiac disease. A recent study published in the journal Pediatric Research indicates that a peptide that occurs naturally in durum wheat may protect against the effects of celiac disease by acting as an antagonist against gliadin peptides associated with abnormal immune response. The study was conducted by a team of Italian researchers made up of Drs. Marco Silano, Rita DiBenedetto, Antonello Trecca, Gioachhino Arrabiato, Fabiana Leonardi, Massimo De Vincenzi. The research team set out to assess the antagonistic effects of 10mer, a decapeptide (sequence QQPQDAVQPF) from the alcohol–soluble protein portion of durum wheat, and to evaluate its prospects for preventing gliadin peptides from activating celiac peripheral blood lymphocytes. The team extracted peripheral blood mononuclear cells from children with celiac disease who tested DQ2-positive, and from a healthy control group. These samples were then incubated with the peptic-tryptic digest of bread wheat gliadin (GLP) and peptide 62-75 from [alpha]-gliadin, both alone and separately with 10mer. PBMC proliferation, release of pro-inflammatory Th1 cytokines interferon-[gamma] and tumor necrosis factor-[alpha], release of immuno-regulatory cytokine IL-10, and analysis of CD25 expression as indexes of lymphocytes activation were performed. Exposure to wheat gliadin peptide and peptide 62-75 from [alpha] gliadin both showed increased activation of lymphocytes. However, the incubation samples with 10mer showed inhibited lymphocyte action. The study indicates that naturally occurring peptide 10mer in durum wheat may protect against lymphocyte activity in patients with celiac disease, and that further study and evaluation of these findings is warranted. Pediatric Research. 61(1):67-71, January 2007. -
Peptide Discovery Gets To The Guts Of Celiac Disease
Scott Adams posted an article in Conferences, Publicity, Pregnancy, Church, Bread Machines, Distillation & Beer
July 2000 - Chemistry In Britain Summarized by Linda Blanchard Celiac.com 01/10/2001 - The article states that Oxford physicians and scientists did an experiment in which celiac patients who were previously on a gluten-free diet were fed a series of human-made peptides that are copies of portions of the peptide chains that are found in the gliadin portion of wheat. The hope was that by feeding those in the study overlapping partial chains, and then testing their blood for T-cells afterward, they could find which specific portion of the wheat protein set off the immune reaction in celiacs. One single peptide did trigger the reaction. Now that it has been identified, it is hoped that some solutions to the problems caused by celiac disease may become available. Two approaches seem to involve "turning off" the reaction -- its thought that offering a megadose of the particular peptide might turn the immune reaction off. Another method would involve offering a peptide that was very similar to the offending piece of wheat protein -- but just enough different that it might "turn off" the reaction. Another possibility is, of course, genetically modified wheat. It should be possible for scientists to develop a wheat that has a different peptide in the place of the offender, which would hopefully look, taste, and act as wheat does in normal baking without triggering celiac reactions. -
Immunodominant Peptide Identified in Celiac Disease
Scott Adams posted an article in Celiac Disease Diagnosis, Testing & Treatment
Nat Med 2000;6:337-342. (March 1, 2000) see also: BMJ 2000;320:736 (March 18, 2000) (Celiac.com 03/17/2000) Researchers in Britain have identified a dominant epitope of the A-gliadin protein of wheat that is linked to the cause of celiac disease. The findings could eventually influence the diagnosis and treatment of the disease. With the new information Wheat could be genetically engineered to be non-toxic for celiacs, according to Dr. Robert P. Anderson. Also, modified versions of T cell epitopes can have unique antagonistic effects that switch off particular immune responses. The identification of this peptide could be used to develop a blood tests to better diagnose celiac disease, and could also be used to better test food for celiac toxicity. Dr. Anderson and his University of Oxford colleagues used a series of 15 amino acid peptides along the A-gliadin sequence (alpha gluten) to stimulate in patients with celiac disease their peripheral blood mononuclear cells, or PBMCs. The peptides were either unmodified or were treated with tissue transglutaminase, which, in the presence or absence of lysine, will convert glutamine to glutamate. Researchers successfully stimulated PBMCs in celiac patients who were in remission due to a gluten-free diet with a gluten challenge. Patients were fed wheat bread for either a half day, 3 days, or 10 days, and healthy, non-celiac patients that were fed wheat bread each day for 4 weeks were used as controls. The researchers successfully produced PBMCs from the celiac disease group, who secreted interferon-gamma 6-8 days later, in response to a particular pool of A-gliadin peptides, which had been treated with tissue transglutaminase. A 17-amino-acid peptide, corresponding to the partially deamidated peptide of A-gliadin amino acids 57-73, was optimal for inducing the interferon-gamma secretion, and the responses were restricted to those with HLA-DQ2. According to Dr. Anderson: On a more general level, the finding that a host enzyme modifies peptides that are then recognized by the immune system suggests that searching for epitopes important in disease may be more complex than simply reading off protein sequences from sequenced genes. Further, modification of the peptide by tissue transglutaminase that is present in the intestinal lining increases binding of the peptide to HLA-DQ. The researchers also point out that T cells that are responsive to the same A-gliadin peptide are readily induced in celiac disease despite many years of following a gluten-free diet, which indicates a persistence of memory T cells that could be caused by continuing exposure to trace amounts of gluten. The researchers only looked at the A-gliadin peptide, and point out that there is a possibility that other peptides that are structurally unrelated to A-gliadin are also important in celiac disease.