The Ethiopian Cereal Tef in Celiac Disease
http://www.100md.com
《新英格兰医药杂志》
To the Editor: Celiac disease is caused by aberrant T-cell responses to wheat gluten and the gluten-like proteins in barley and rye.1 The only cure for the disease is a lifelong gluten-free diet. Although consumption of oats is generally considered safe for patients with celiac disease,2 recent studies indicate that the grain does contain T-cell–stimulatory epitopes1,3 and that symptoms of celiac disease develop in some patients after the consumption of oats.4 A cereal lacking T-cell–stimulatory peptides would thus be of great value to patients with celiac disease. Tef (Eragrostis tef) is a cereal traditionally grown in Ethiopia and used to make injera, or flat bread. Tef flour can substitute for wheat flour in almost all applications, and the nutritional value of tef is similar to that of wheat (www.ipgri.cgiar.org/publications/pdf/279.pdf). Since tef is only distantly related phylogenetically to wheat, barley, and rye, we have investigated the potential safety of tef for consumption by patients with celiac disease.
For this purpose, pepsin and trypsin digests were prepared of 14 varieties of tef (provided by Soil and Crop, Assen, the Netherlands) and of wheat, barley, rye, triticale, oats, maize, and rice as controls. These digests were analyzed for the presence of T-cell–stimulatory epitopes of -gliadin (Figure 1A), -gliadin, and low- and high-molecular-weight glutenin (not shown) by T-cell and antibody-based assays.5 In addition, extracted proteins of one tef variety were separated by two-dimensional gel electrophoresis and analyzed by Western blotting and mass spectrometry. Although T-cell–stimulatory epitopes were detected in protein digests of known gluten-containing cereals, all tef varieties lacked these epitopes (Figure 1A). In a similar manner, with monoclonal antibodies specific for T-cell–stimulatory gluten peptides, comparable results with the various control preparations were obtained, whereas 12 of the 14 tef preparations tested negative (Figure 1B). With two tef varieties, weak antibody responses were found, even though Western blot and mass spectrometric analysis detected no gluten-like proteins (which were readily detected in barley, rye, and oats) (not shown). Therefore, this response was probably based on antibody cross-reactivity to nongluten molecules.
Figure 1. Analyses Showing an Absence of Gluten-Derived T-Cell Epitopes in Tef.
Pepsin and trypsin digests of wheat, barley, rye, triticale, oats, maize, rice, and tef (14 varieties) were analyzed for the presence of an immunodominant -gliadin–derived T-cell–stimulatory peptide. To make possible the detection of T cells, the digests were treated with tissue transglutaminase before testing.1 Panel A shows stimulation of a Glia-2/9 epitope–specific T-cell clone. Panel B shows the concentration of a Glia-9 T-cell epitope as measured with an antibody-based assay. The experiment displayed in Panel A was performed in triplicate, and the experiment displayed in Panel B was performed in duplicate. The mean (±SD) value of each measurement is shown. Similar experiments with -gliadin and low- and high-molecular-weight glutenin–specific T-cell clones and antibodies also failed to demonstrate the presence of gluten-like peptides in tef. All experiments were repeated at least twice.
In conclusion, within the limits of the currently available methods, no gluten or gluten homologues could be detected in the tef varieties tested. This finding indicates that tef may be suitable for use in the diet of patients with celiac disease. Ultimately, the study of tef consumption by patients with celiac disease in remission will be needed in order to determine whether tef is safe for these patients.
Liesbeth Spaenij-Dekking, Ph.D.
Yvonne Kooy-Winkelaar
Frits Koning, Ph.D.
Leiden University Medical Center
2300 RC Leiden, the Netherlands
References
Vader LW, Stepniak DT, Bunnik EM, et al. Characterization of cereal toxicity for celiac disease patients based on protein homology in grains. Gastroenterology 2003;125:1105-1113.
Janatuinen EK, Pikkarainen PH, Kemppainen TA, et al. A comparison of diets with and without oats in adults with celiac disease. N Engl J Med 1995;333:1033-1037.
Arentz-Hansen H, Fleckenstein B, Molberg O, et al. The molecular basis for oat intolerance in patients with celiac disease. PLoS Med 2004;1:84-92.
Lundin KE, Nilsen EM, Scott HG, et al. Oats induced villous atrophy in coeliac disease. Gut 2003;52:1649-1652.
Spaenij-Dekking EH, Kooy-Winkelaar EM, Nieuwenhuizen WF, Drijfhout JW, Koning F. A novel and sensitive method for the detection of T cell stimulatory epitopes of alpha/beta- and gamma-gliadin. Gut 2004;53:1267-1273.
For this purpose, pepsin and trypsin digests were prepared of 14 varieties of tef (provided by Soil and Crop, Assen, the Netherlands) and of wheat, barley, rye, triticale, oats, maize, and rice as controls. These digests were analyzed for the presence of T-cell–stimulatory epitopes of -gliadin (Figure 1A), -gliadin, and low- and high-molecular-weight glutenin (not shown) by T-cell and antibody-based assays.5 In addition, extracted proteins of one tef variety were separated by two-dimensional gel electrophoresis and analyzed by Western blotting and mass spectrometry. Although T-cell–stimulatory epitopes were detected in protein digests of known gluten-containing cereals, all tef varieties lacked these epitopes (Figure 1A). In a similar manner, with monoclonal antibodies specific for T-cell–stimulatory gluten peptides, comparable results with the various control preparations were obtained, whereas 12 of the 14 tef preparations tested negative (Figure 1B). With two tef varieties, weak antibody responses were found, even though Western blot and mass spectrometric analysis detected no gluten-like proteins (which were readily detected in barley, rye, and oats) (not shown). Therefore, this response was probably based on antibody cross-reactivity to nongluten molecules.
Figure 1. Analyses Showing an Absence of Gluten-Derived T-Cell Epitopes in Tef.
Pepsin and trypsin digests of wheat, barley, rye, triticale, oats, maize, rice, and tef (14 varieties) were analyzed for the presence of an immunodominant -gliadin–derived T-cell–stimulatory peptide. To make possible the detection of T cells, the digests were treated with tissue transglutaminase before testing.1 Panel A shows stimulation of a Glia-2/9 epitope–specific T-cell clone. Panel B shows the concentration of a Glia-9 T-cell epitope as measured with an antibody-based assay. The experiment displayed in Panel A was performed in triplicate, and the experiment displayed in Panel B was performed in duplicate. The mean (±SD) value of each measurement is shown. Similar experiments with -gliadin and low- and high-molecular-weight glutenin–specific T-cell clones and antibodies also failed to demonstrate the presence of gluten-like peptides in tef. All experiments were repeated at least twice.
In conclusion, within the limits of the currently available methods, no gluten or gluten homologues could be detected in the tef varieties tested. This finding indicates that tef may be suitable for use in the diet of patients with celiac disease. Ultimately, the study of tef consumption by patients with celiac disease in remission will be needed in order to determine whether tef is safe for these patients.
Liesbeth Spaenij-Dekking, Ph.D.
Yvonne Kooy-Winkelaar
Frits Koning, Ph.D.
Leiden University Medical Center
2300 RC Leiden, the Netherlands
References
Vader LW, Stepniak DT, Bunnik EM, et al. Characterization of cereal toxicity for celiac disease patients based on protein homology in grains. Gastroenterology 2003;125:1105-1113.
Janatuinen EK, Pikkarainen PH, Kemppainen TA, et al. A comparison of diets with and without oats in adults with celiac disease. N Engl J Med 1995;333:1033-1037.
Arentz-Hansen H, Fleckenstein B, Molberg O, et al. The molecular basis for oat intolerance in patients with celiac disease. PLoS Med 2004;1:84-92.
Lundin KE, Nilsen EM, Scott HG, et al. Oats induced villous atrophy in coeliac disease. Gut 2003;52:1649-1652.
Spaenij-Dekking EH, Kooy-Winkelaar EM, Nieuwenhuizen WF, Drijfhout JW, Koning F. A novel and sensitive method for the detection of T cell stimulatory epitopes of alpha/beta- and gamma-gliadin. Gut 2004;53:1267-1273.