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Wheat genotypes containing minimally harmful gluten sequences

by luciano

“Previous studies have documented that landraces and older wheat varieties contain more diverse gene combinations for prolamins (wheat proteins) in comparison to modern varieties (10, 11). Literature shows variations for specific gene sequences mainly in the epitopic regions of Glia-α9, Glia-α2, Glia-α20, and Glia-α in older landraces (9). In the last decade in the context of CD, the immunogenicity of T-cell specific epitopes has been bought to the forefront (9, 12). The immunogenic potential amongst different hexaploid wheat varieties is variable; hence it is possible that there are breeding-induced differences in the presence and expression of T-cell stimulatory epitopes in modern varieties of wheat (13, 14). This raises the question of, whether there is any specific variety of wheat which is less immunogenic and can be used in breeding programs for developing a wheat genotype completely safe for consumption by patients suffering from CD”.

Highlights:
• The identification of less/non-immunogenic wheat species is an important milestone that could help patients or even prevent CD.
• With the use of gluten-specific T-cells and PBMCs, wheat genotypes containing minimally harmful gluten sequences can be selected.

Adverse Reactions to Wheat or Wheat Components.

by luciano

The research we present is an excellent compendium of current knowledge on non-celiac gluten sensitivity

“Abstract: Wheat is an important staple food globally, providing a significant contribution to daily energy, fiber, and micronutrient intake. Observational evidence for health impacts of consuming more whole grains, among which wheat is a major contributor, points to significant risk reduction for diabetes, cardiovascular disease, and colon cancer. However, specific wheat components may also elicit adverse physical reactions in susceptible individuals such as celiac disease (CD) and wheat allergy (WA). Recently, broad coverage in the popular and social media has suggested that wheat consumption leads to a wide range of adverse health effects. This has motivated many consumers to avoid or reduce their consumption of foods that contain wheat/gluten, despite the absence of diagnosed CD or WA, raising questions about underlying mechanisms and possible nocebo effects. However, recent studies did show that some individuals may suffer from adverse reactions in absence of CD and WA. This condition is called non-celiac gluten sensitivity (NCGS) or non-celiac wheat sensitivity (NCWS). In addition to gluten, wheat and derived products contain many other components which may trigger symptoms, including inhibitors of α-amylase and trypsin (ATIs), lectins, and rapidly fermentable carbohydrates (FODMAPs). Furthermore, the way in which foods are being processed, such as the use of yeast or sourdough fermentation, fermentation time and baking conditions, may also affect the presence and bioactivity of these components. The present review systematically describes the characteristics of wheat-related intolerances, including their etiology, prevalence, the components responsible, diagnosis, and strategies to reduce adverse reactions.

Extract from the study:

Non-Celiac Gluten/Wheat Sensitivity
During recent years a third group of people has been classified who experience symptoms after eating wheat products, but have been diagnosed not to suffer from either WA or CD. Mostly these individuals are self diagnosed wheat intolerant/sensitive. In these individuals, irritable bowel syndrome (IBS)-like gastrointestinal symptoms and extra-intestinal complaints occur, which improve on a gluten-free diet. This group of patients is referred to as “non-celiac gluten sensitivity” (NCGS), or the more recently, “non-celiac wheat sensitivity” (NCWS). Di Sabatino emphasizes that NCWS is not a homogeneous disease syndrome (such as CD and WA), but rather a heterogeneous syndrome (Di Sabatino & Corazza, 2012). It is probable that the underlying causes and mechanisms are not the same for all people with NCWS and that reactions may be caused by different components of wheat or grain (products) and involving different host factors. Ludvigsson et al. (2013) defined NCGS as follows: one or more of a variety of immunological, morphological, or symptomatic manifestations that are precipitated by the ingestion of gluten in individuals in whom CD has been excluded. However, despite the word “gluten” in the currently most cited definition “NCGS,” it is far from certain that the gluten is the (main) cause of the symptoms observed. The more recent term “NCWS” was adopted since it was noted that gluten (NCGS) may not be the real cause (Biesiekierski, Peters, et al., 2013; Skodje et al., 2018). For that reason, we will use the term NCWS as most appropriate in the remainder of this article.

Sensitivity to wheat, gluten and FODMAPs in IBS: facts or fiction?

by luciano

 

ABSTRACT
IBS is one of the most common types of functional bowel disorder. Increasing attention has been paid to the causative role of food in IBS. Food ingestion precipitates or exacerbates symptoms, such as abdominal pain and bloating in patients with IBS through different hypothesised mechanisms including immune and mast cell activation, mechanoreceptor stimulation and chemosensory activation. Wheat is regarded as one of the most relevant IBS triggers, although which component(s) of this cereal is/are involved remain(s) unknown. Gluten, other wheat proteins, for example, amylase-trypsin inhibitors, and fructans (the latter belonging to fermentable oligo-di-mono-saccharides and polyols (FODMAPs)), have been identified as possible factors for symptom generation/exacerbation. This uncertainty on the true culprit(s) opened a scenario of semantic definitions favoured by the discordant results of double-blind placebo-controlled trials, which have generated various terms ranging from non-coeliac gluten sensitivity to the broader one of non-coeliac wheat or wheat protein sensitivity or, even, FODMAP sensitivity. The role of FODMAPs in eliciting the clinical picture of IBS goes further since these short-chain carbohydrates are found in many other dietary components, including vegetables and fruits. In this review, we assessed current literature in order to unravel whether gluten/wheat/FODMAP sensitivity represent ‘facts’ and not ‘fiction’ in IBS symptoms. This knowledge is expected to promote standardisation in dietary strategies (gluten/wheat-free and low FODMAP) as effective measures for the management of IBS symptoms.

Extract from study:

WHEAT SENSITIVITY
Wheat is considered one of the foods known to evoke IBS symptoms. However, which component(s) of wheat is/are actually responsible for these clinical effects still remain(s) an unsettled issue. The two parts of wheat that are thought to have a mechanistic effect comprise proteins (primarily, but not exclusively, gluten) and carbohydrates (primarily indigestible short-chain components, FODMAPs). Two distinct views characterise the clinical debate: one line identifies wheat proteins as a precipitating/perpetuating factor leading to symptoms, while the other believes that FODMAPs are the major trigger for IBS.

The controversy over nomenclature
If gluten is a major trigger for IBS, it expands the gluten-related disorders by adding a new entity now referred to as non-coeliac gluten sensitivity (NCGS). Indeed, coeliac disease-like abnormalities were reported in a subgroup of patients with IBS many years ago. A recent expert group of researchers reached unanimous consensus attesting the existence of a syndrome triggered by gluten ingestion. This syndrome recognises a wide spectrum of symptoms and manifestations including an IBS-like phenotype, along with an extra-intestinal phenotype, that is, malaise, fatigue, headache, numbness, mental confusion (‘brain fog’), anxiety, sleep abnormalities, fibromyalgia-like symptoms and skin rash. In addition, other possible clinical features include gastroesophageal reflux disease, aphthous stomatitis, anaemia, depression, asthma and rhinitis. Symptoms or other manifestations occur shortly after gluten consumption and disappear or recur in a few hours (or days) after gluten withdrawal or challenge. A fundamental prerequisite for suspecting NCGS is to rule out all the established gluten/wheat disorders, comprising coeliac disease (CD), gluten ataxia, dermatitis herpetiformis and wheat allergy. The major issue not addressed by the consensus opinion was that gluten is only one protein contained within wheat. Other proteins, such as amylase-trypsin inhibitors (ATIs), are strong activators of innate immune responses in monocytes, macrophages and dendritic cells. Furthermore, wheat germ agglutinin, which has epithelial-damaging and immune effects at very low doses at least in vitro, might also contribute to both intestinal and extraintestinal manifestations of NCGS. Consequently, a further development of this research field led to suggestions of a broader term, non-coeliac wheat sensitivity (NCWS). The problems with this term are twofold. First, rye and barley may be inappropriately excluded. Second, the term will refer to any wheat component that might be causally related to induction of symptoms and, therefore, will also include fructans (FODMAPs). It will then have a very nonspecific connotation in IBS. A more correct term would then be non-coeliac wheat protein sensitivity (NCWPS) since this does not attribute effects to gluten without evidence of such specificity, eliminates the issue of fructan-induced symptoms and avoids the unknown contribution of rye and barley proteins to the symptoms. Both NCGS, the currently accepted term, and NCWPS will be used subsequently in this paper.

Reintrodution gluten after after some period on a gluten-free diet for NCGS (non celiac gluten sensivity)

by luciano

“Once the diagnosis of NCGS is reasonably reached, the management and follow-up of patients is completely obscure. A logical approach is to undertake a gluten-free dietary regimen for a limited period (e.g., six months), followed by the gradual reintroduction of gluten. During the gluten-free diet, the ingestion of prolamine peptide (gliadin)-derived from wheat, rye, barley, oats, bulgur, and hybrids of these cereal grains-should be avoided. Rice, corn, and potatoes have been the typical substitutes, but nowadays other different cereals and pseudocereals, such as amaranth, buckwheat, manioc, fonio, teff, millet, quinoa, and sorghum, can be used. After some period on a gluten-free diet, the reintroduction of gluten can start with cereals of low gluten content (e.g., oats). In addition, einkorn farro (Triticum monococcum) can be used, having no direct in vitro or ex vivo toxicity and low (7%) gluten content[41]”. (Non-celiac gluten sensitivity: Time for sifting the grain. Luca Elli, Leda Roncoroni, and Maria Teresa Bardella. Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved).

Quantitation of the immunodominant 33-mer peptide from α-gliadin in wheat flours

by luciano

In wheat there are multiple fractions able to activate the adverse response of the human immune system. Among these fractions the most active is that called 33-mer because it is the most resistant to human digestion and because it contains six copies of the three toxic epitopes and its intermolecular bonds are very strong. It is therefore important to know the quantity of this fraction in the grains. The study of which some parts are reported, examined 57 different types of wheat, ancient and modern, noting that the difference, in all soft wheat and spelt flour, of 33-mer is wide: from 90.9 to 602.6 μg / g made with flour. On the other hand, its presence in monococcum wheat and durum wheat was not detected. These results take on great importance because they allow grains to be chosen with limited or no presence of this important toxic fraction for products that are more suitable for non-celiac gluten sensitive people or those suffering from gluten disorders.

“All gluten protein fractions, namely the alcohol-soluble prolamins and the insoluble glutelins, contain CD-active epitopes3. The prolamin fraction is particularly rich in proline and glutamine and the numerous proline residues lead to a high resistance to complete proteolytic digestion by human gastric, pancreatic, and brushborder enzymes. Studies by Shan et al. (2002) showed that a large 33-mer peptide (LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF) from α2-gliadin (position in the amino acid sequence of α2-gliadin: 56–88) is resistant to cleavage by intestinal peptidases4,5. The 33-mer is widely called the most immunodominant gluten peptide4,6,7, because it contains three overlapping T-cell epitopes, namely PFPQPQLPY (DQ2.5-glia-α1a, one copy), PYPQPQLPY (DQ2.5-glia-α1b, two copies) and PQPQLPYPQ (DQ2.5-glia-α2, three copies)3, which result in the initiation of a strong immune response.