Degradation of coeliac disease-inducing rye secalin by germinating cereal enzymes: diminishing toxic effects in intestinal epithelial cells

Abstract

SummaryCurrently the only treatment for coeliac disease is a lifelong gluten-free diet excluding food products containing wheat, rye and barley. There is, however, only scarce evidence as to harmful effects of rye in coeliac disease. To confirm the assumption that rye should be excluded from the coeliac patient's diet, we now sought to establish whether rye secalin activates toxic reactions in vitro in intestinal epithelial cell models as extensively as wheat gliadin. Further, we investigated the efficacy of germinating cereal enzymes from oat, wheat and barley to hydrolyse secalin into short fragments and whether secalin-induced harmful effects can be reduced by such pretreatment. In the current study, secalin elicited toxic reactions in intestinal Caco-2 epithelial cells similarly to gliadin: it induced epithelial cell layer permeability, tight junctional protein occludin and ZO-1 distortion and actin reorganization. In high-performance liquid chromatography and mass spectroscopy (HPLC-MS), germinating barley enzymes provided the most efficient degradation of secalin and gliadin peptides and was thus selected for further in vitro analysis. After germinating barley enzyme pretreatment, all toxic reactions induced by secalin were ameliorated. We conclude that germinating enzymes from barley are particularly efficient in the degradation of rye secalin. In future, these enzymes might be utilized as a novel medical treatment for coeliac disease or in food processing in order to develop highquality coeliac-safe food products.

Novel Treatments for Celiac Disease: Glutenases and Beyond

“…These enzymes are also able to exert their proteolytic function in the pH range present in the gastrointestinal tract, and they are at least moderately resistant to the prevailing harsh environment [20]. As shown in table 1, detoxification capacity of these enzymes has been supported by extensive in vitro, in vivo (in rats and macaques) and ex vivo (using biopsy-derived T cells and small bowel biopsies in organ culture systems) studies [21,22,23,24,25,26,27,28]. As PEP and EP-B2 are complementary as regards their sequence specificities, investigators have thought that a combination of these enzymes would be a dramatically superior therapeutic approach for the treatment of celiac disease [19].…”

“…Based on this, a combination enzyme product ALV003, consisting of 1:1 mixture of barley EP-B2 and Sphingomonas capsulata PEP has been formulated [23]. Following the line of thinking of the combination enzyme therapy, also an entire range of germinating cereal enzymes have been tested for their capability to degrade gluten [26,27]. The major advance in such an approach is that the protease preparation contains all the enzymes that are evolutionarily selected for total cleavage of storage proteins in germinating kernels.…”

Cereals for developing gluten-free products and analytical tools for gluten detection

“…A concrete example is the hydrolysis of rye secalin peptides by cereal enzymes from germinating barley. These released short fragments and reduced the toxicity of the rye (Stenman et al, 2010).…”

The Use of Different Proteases to Hydrolyze Gliadins

“…In addition, other specific endopeptidases with cleavage activity for Pro-residues of different substrates have been reported, e.g. endopeptidase from Lactobacillus helveticus CNRZ32 (Chen et al, 2003), metalloendoproteinase from Penicillium citricum (Doi et al, 2004) and prolyl-endoprotease from Aspergillus niger (Stepniak et al, 2006). The latter one is promising tool for celiac disease therapy.…”

“…In recent years, several attractive therapeutic strategies have been arisen (see review Makharia, 2014) from which enzyme therapy is proposed as one of the future options to reduce or even eliminate the celiac-active properties of gliadins. The enzyme therapy investigated two different approaches focused on microbial prolyl- (Stenman et al, 2009(Stenman et al, , 2010. The PEPs family has ability to cleave internal proline residues within a peptide sequence.…”