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Jefferson Adams posted an article in Celiac Disease & Gluten Intolerance ResearchCeliac.com 03/24/2014 - Two new studies have confirmed colonization of gluten-degrading bacteria in the human mouth and in the upper gastrointestinal tracts respectively. Both studies come out of the Department of Periodontology and Oral Biology, Boston University Henry M. Goldman School of Dental Medicine in Boston, Massachusetts. The research teams included Maram Zamakhchari, Guoxian Wei, Floyd Dewhirst, Jaeseop Lee, Detlef Schuppan, Frank G. Oppenheim, and Eva J. Helmerhorst. Gluten is notoriously hard for mammals to digest, because gliadin proteins resist mammalian proteolytic enzymes in the gut, so researchers wanted to find sources of gluten-digesting microbial enzymes from the upper gastro-intestinal tract. These microbial enzymes have the potential to neutralize the gluten peptides that act as celiac disease triggers. In the first study the researchers assessed proteolytic activity in suspended dental plaque towards a) gliadin-derived paranitroanilide(pNA)-linked synthetic enzyme substrates a mixture of natural gliadins and c) synthetic highly immunogenic gliadin peptides (33-mer of α2-gliadin and 26-mer of γ-gliadin). In addition, they conducted gliadin zymography to establish the approximate molecular weights and pH activity profiles of the gliadin-degrading oral enzymes and performed liquid iso-electric focusing to determine overall enzyme iso-electric points. Their results provide the first known evidence of gluten-degrading microorganisms associated with the upper gastro-intestinal tract. Such microorganisms may play a hitherto unappreciated role in the digestion of dietary gluten and thus protection from celiac disease in subjects at risk. In the second study, the team employed a selective plating strategy using gluten agar to obtain oral microorganisms with gluten-degrading capacity. They then used16S rDNA gene sequencing to carry out microbial speciations. To determine enzyme activity, they used gliadin-derived enzymatic substrates, gliadins in solution, gliadin zymography, and 33-mer a-gliadin and 26-mer c-gliadin immunogenic peptides. They separated fragments of the gliadin peptides by RP-HPLC, and structurally characterized them using mass spectrometry. They found that strains Rothia mucilaginosa and Rothia aeria showed high gluten-degrading activity. For example, gliadins (250 mg/ml) added to Rothia cell suspensions (OD620 1.2) degraded by 50% after 30 minutes of incubation. Importantly, the 33-mer and 26-mer immunogenic peptides were also cleaved, primarily C-terminal to Xaa-Pro-Gln (XPQ) and Xaa-Pro-Tyr (XPY). The major gliadin-degrading enzymes produced by the Rothia strains were 70–75 kDa in size, and the enzyme expressed by Rothia aeria was active over a wide pH range (pH 3–10). While the human digestive enzyme system lacks the capacity to cleave immunogenic gluten, such activities are naturally present in the oral microbial enzyme repertoire. Taken together, these studies suggest a potential for these bacteria to fuel the development of compounds that can degrade of harmful gluten peptides that trigger celiac disease in susceptible individuals. Source: PLoS One. 2011;6(9):e24455. doi: 10.1371/journal.pone.0024455. http://www.ncbi.nlm.nih.gov/pubmed/20948997
Jefferson Adams posted an article in Celiac Disease Diagnosis, Testing & TreatmentCeliac.com 10/07/2009 - A team of Maltese researchers, led by genetics specialist Christian Scerri, has discovered that a previously unassociated gene contributes to the development of celiac disease. The association of the gene, a variant of a gene called CD59, is the result of three years of research at a University of Malta lab. The research team made the discovery after examining the DNA of six people who suffered from gluten intolerance, together with 9 close relatives. Armed with about $35,000 in research funds provided by the Malta Council for Science and Technology, the research team set out to examine the DNA of each family member along with their different genes. "If you have a grandmother, a mother and a son who all suffer from a particular disease, we will look for the part of DNA that is common in all three," Scerri said. Once the researchers isolated the matching parts of the DNA, the researchers begging combing through all the different genes in that section of the DNA. Several prior studies have shown that only people with a certain type of the molecule human leukocyte antigen, called HLA-DQ2/DQ8, were pre-disposed to celiac disease. HLA-DQ2/DQ8 is found in about 30 per cent of the worldwide population. Although HLA-DQ2/DQ8 does not cause gluten intolerance on its own, it can combine with a number of genes to cause celiac disease. According to Dr. Scerri, the results showed that "all those patients who suffered from celiac disease had both HLA-DQ2/DQ8 and a variant of CD59." The study also confirmed that people who had HLA-DQ2/DQ8 or CD59 alone did not suffer from celiac disease, providing strong evidence that the two combine to cause gluten intolerance. The gene variant was also rare in Malta and was not found among another 99 families who have members with celiac disease. "This seems to be the only family in Malta which has this gene," Dr Scerri says of the 17-strong family that was tested. Though the gene is quite rare, the research is crucial, as it will likely lead to further study to discover how specific genes bring about particular conditions. Dr Scerri hopes to have additional staff in place to begin research by the end of next year when a $7 million restructuring of the University's molecular genetics lab would be finalized. Source: Times of Malta
Scott Adams posted an article in Gluten-Free Grains and FloursGastroenterology, Oct 2003, Vol 125, No 4, p1105-13 Celiac.com 10/30/2003 – It has long been known that celiac disease is caused by T-cell responses to wheat gluten-derived peptides, but the toxicity of other widely consumed grains has not been well studied. The researchers who conducted this study were aimed at determining the toxic T-cell stimulatory properties of barley hordeins, rye secalins, and oat avenins. Except for one instance, they found that there were no identical T-cell stimulatory gluten peptide matches in these grains. There were, however, similar responses found in "11 homologous sequences in hordeins, secalins, and avenins located in regions similar to those in the original gluten proteins," and seven of the 11 peptides were recognized by gluten-specific T-cell lines and/or clones from patients with celiac disease. The team discovered that key amino acids can be substituted, which will either partially or totally stop the T-cell stimulation by the gluten peptides, and that "single nucleotide substitutions in gluten genes will suffice to induce these effects." The researchers conclude: "These results show that the disease-inducing properties of barley and rye can in part be explained by T-cell cross-reactivity against gluten-, secalin-, and hordein-derived peptides. Moreover, the results provide a first step toward a rational strategy for gluten detoxification via targeted mutagenesis at the genetic level."