The gastrointestinal tract is a major reservoir of a wide variety of microorganisms. The role of the colonizing microorganisms in contributing to host metabolic processes and overall gastrointestinal health is becoming more widely recognized. Recent work in our laboratory has revealed that bacteria residing in the oral cavity, the entrance to the gastrointestinal tract, are able to degrade dietary gluten. Glutens elicit immunologic reactions and serious clinical conditions in patients suffering from celiac disease. The basis of this disease is an auto-immune disorder in which a host-anti-self response is triggered by gluten-derived cytotoxic peptides. Patients with overt celiac disease suffer from gastroenteropathy and are at risk for malnutrition, anemia, osteoporosis and gastrointestinal malignancies such as lymphoma and adenocarcinoma. To avoid gluten toxicity, patients are required to adherence to a strict gluten-free diet, which is currently the only treatment option available. However, the dietary restriction approach requires a life-long commitment and represents a significant burden to the patient. The discovery of natural gluten degrading microorganisms from the oral cavity opens a promising new avenue in the quest to neutralize the deleterious effects of glutens. The current application seeks to explore the proteolytic activities of resident gastrointestinal microorganisms and study their potential to fragment gluten proteins into non-toxic peptides.
The specific aims are: (1) To identify gluten-degrading microorganism(s) in dental plaque and fecal specimens;(2) To define protease cleavage site specificity and assess the abolishment of immunogenic gliadin regions, and to determine pH activity profiles;(3) To assess gliadin detoxification by selected microbes and purified enzyme preparations in a T-cell proliferation assay and in an in vivo model for celiac disease;(4) To characterize, clone and recombinantly express the gene(s) of the most promising enzyme(s). Reduction of gluten toxicity by natural colonizers of the gastrointestinal tract would offer novel treatment perspectives in the form of probiotics or applications of pure gluten-degrading enzymes.

Public Health Relevance

Glutens are proteins which are not tolerated by people who are allergic to gluten and by patients suffering from celiac disease. A promising approach to reduce gluten toxicity is using enzymes to degrade these proteins into non-toxic fragments. The current application seeks to identify gluten-neutralizing enzymes expressed by resident microbes from the human gastrointestinal tract.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Gastrointestinal Mucosal Pathobiology Study Section (GMPB)
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Mills, Melody
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Boston University
Schools of Dentistry
United States
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Tian, Na; Faller, Lina; Leffler, Daniel A et al. (2017) Salivary Gluten Degradation and Oral Microbial Profiles in Healthy Individuals and Celiac Disease Patients. Appl Environ Microbiol 83:
Heller, D; Helmerhorst, E J; Oppenheim, F G (2017) Saliva and Serum Protein Exchange at the Tooth Enamel Surface. J Dent Res 96:437-443
Heller, D; Helmerhorst, E J; Gower, A C et al. (2016) Microbial Diversity in the Early In Vivo-Formed Dental Biofilm. Appl Environ Microbiol 82:1881-8
Tian, Na; Leffler, Daniel A; Kelly, Ciaran P et al. (2015) Despite sequence homologies to gluten, salivary proline-rich proteins do not elicit immune responses central to the pathogenesis of celiac disease. Am J Physiol Gastrointest Liver Physiol 309:G910-7
Wei, Guoxian; Tian, Na; Valery, Adriana C et al. (2015) Identification of Pseudolysin (lasB) as an Aciduric Gluten-Degrading Enzyme with High Therapeutic Potential for Celiac Disease. Am J Gastroenterol 110:899-908
Tian, Na; Messana, Irene; Leffler, Daniel A et al. (2015) Salivary proline-rich proteins and gluten: Do structural similarities suggest a role in celiac disease? Proteomics Clin Appl 9:953-64
Helmerhorst, Eva J; Wei, Guoxian (2014) Experimental Strategy to Discover Microbes with Gluten-degrading Enzyme Activities. Proc SPIE Int Soc Opt Eng 9112:
Vukosavljevic, D; Hutter, J L; Helmerhorst, E J et al. (2014) Nanoscale adhesion forces between enamel pellicle proteins and hydroxyapatite. J Dent Res 93:514-9
Tian, Na; Wei, Guoxian; Schuppan, Detlef et al. (2014) Effect of Rothia mucilaginosa enzymes on gliadin (gluten) structure, deamidation, and immunogenic epitopes relevant to celiac disease. Am J Physiol Gastrointest Liver Physiol 307:G769-76
Iavarone, Federica; D'Alessandro, Alfredo; Tian, Na et al. (2014) High-resolution high-performance liquid chromatography with electrospray ionization mass spectrometry and tandem mass spectrometry characterization of a new isoform of human salivary acidic proline-rich proteins named Roma-Boston Ser?? (Phos) ? Phe varian J Sep Sci 37:1896-902

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