Tolerability of an Ancient Grain in Patients With Non-Celiac Wheat Sensitivity

Patients suffering from wheat-related troubles, in absence of celiac disease or wheat allergy diagnosis, can suffer from non-celiac wheat sensitivity (NCWS). This is characterized by both gastrointestinal (GI) and extra-intestinal symptoms, which improve with the elimination of wheat intake. To date no definitive explanation of pathogenetic mechanisms of NCWS has been proved, and, similarly, no specific non-invasive diagnostic biomarker has been recognized. A real need of strict adherence to wheat-free diet (WFD) in NCWS has never been demonstrated. In this context, research is actively trying to find wheat varieties with absent or low immune-reactivity to be used for the treatment of NCWS patients. Preliminary evidence supports the assumption that diploid wheat species, as Triticum monococcum (TM), compared to common ones (Triticum aestivum (TA), could possess a lower immunogenic potential in NCWS patients. The first objective of our project is to verify whether the use of a diploid wheat (TM), with a lower concentrations and bioactivity of Amylase-Trypsin-Inhibitors (ATIs) and with gliadin proteins with a better digestibility, compared to a hexaploid one (TA) could improve both symptoms and quality of life (QoL) of NCWS subjects. The second objective is the identification of non-invasive serological biomarkers for NCWS diagnosis. The third objective is to identify T cell lymphocytes able to recognize cognate peptides from wheat proteins to better classify and monitor patients affected by NCWS. To achieve these results we planned a prospective, double-blind clinical trial with crossover, in which patients already diagnosed with NCWS (according to international criteria and with a double-blind placebo-controlled wheat challenge), following a strict WFD, will be exposed in double-blind to both TM and TA. All the patients will be evaluated clinically at the different timepoints with validated scales to assess tolerability of TM. Moreover, their intestinal permeability, immunological activation and gut microbiota patterns will be studied by both in vitro and in vivo techniques. Finally, a randomly chosen subset of patients will be studied through single cell transcriptome and T-cell receptor (TCR) sequencing on rectoscopy biopsy specimens to identify, T cell lymphocytes able to recognize cognate peptides from wheat proteins.

State of the art The association between wheat intake and "wheat-related disorders" (WRDs) has been known for a long time, including pathologies as celiac disease (CD) and wheat allergy (WA). Recently a new non-allergic and non-autoimmune condition has been identified: non-celiac gluten sensitivity (NCGS). This is characterized by both gastrointestinal (GI) symptoms, very similar to those of irritable bowel syndrome (IBS) (eg. abdominal pain, diarrhea, etc.), and extra-intestinal ones (eg. arthromyalgias, anemia, etc.), which improve on a wheat-free diet (WFD).

NCGS prevalence rates range from 0.6% to 13% in the general population, and given the lack of a biomarker, its diagnosis is based on: 1) exclusion of CD and WA; 2) symptom's regression on a WFD; 3) recurrence of symptoms on a double-blind placebo-controlled challenge (DBPCC) with wheat.

Physicians recognize a significant overlap between NCGS and IBS and it is known that IBS affects about 25% of the general population. So, if a percentage of IBS patients could have benefit from a WFD, this would have a paramount impact on its social health costs, being estimated that its indirect costs (eg. loss of work and reduced productivity) are up to $20 billion/years in the US, with an annual cost of $9933 per patient. Furthermore, many patients with IBS-like or upper gastro-esophageal functional-like manifestations self-report a relationship between symptoms onset and wheat ingestion (wheat-intolerance). Nevertheless, a clinical approach with a WFD for all IBS patients would be unmotivated and dangerous, determining also a great economic burden.

In most IBS patients, visceral hypersensitivity may contribute to GI symptoms. Immune activation, due to mucosal mast cells (MCs) in close vicinity to gut nerves, appears to play a role in IBS symptom's onset. A possible neuro-immune interaction in the duodenal submucosa of NCGS patients involving MCs has been described, in order to explain GI symptoms. Other findings in NCGS include an increased infiltration of eosinophils in GI tract, which might produce several inflammatory (ie. eosinophil cationic protein (ECP) and tryptase) and neuromodulatory substances (eg. substance P and VIP).

Several studies have investigated the performance of serum biomarkers panels in differentiating IBS from NCGS and healthy subjects. These included inflammatory cytokines, chemokines, neurotransmitters and antibodies associated with CD. Therefore, it is critically important to investigate the performance of serum biomarkers panels to differentiate "real NCGS" from other conditions.

Having not definitively established whether gluten or some other wheat's component is responsible for symptom's triggering, NCGS has been renamed as non-coeliac wheat sensitivity (NCWS), which would exclude other relevant cereals, such as barley and rye. Some components of wheat other than gluten proteins could be potentially deleterious for NCWS patients, which include fermentable short-chain carbohydrates (FODMAPs) and amylase trypsin inhibitors (ATIs); the latter, activating toll-like receptor 4 complex in monocytes, macrophages and dendritic cells of the intestinal mucosa, might induce innate immunity in both CD and healthy subjects. Finally, some authors have focused on the activation of innate and/or acquired immunity, or gut microbiota modifications.

Research is actively trying to find wheat varieties with absent or low immune reactivity to be used to treat patients with NCWS. Preliminary evidence showed that diploid wheat species, as Triticum monococcum (TM), compared to common ones (Triticum aestivum (TA) and Triticum durum), could possess a lower immunogenic potential in NCWS and IBS patients. It seems that modern wheats contain higher concentrations and bioactivity of ATIs compared with diploid ones, and that gliadin from TM retain a reduced number of immunogenic peptides for CD patients due to a high in vitro digestibility. We found that ATIs from TM are sufficiently different than those from TA, so to determine lack of immune toxicity in CD after proteolytic digestion. Moreover, some data showed that in IBS the consumption of ancient wheat can reduce symptoms and proinflammatory cytokines and improves intestinal dysbiosis. In this context, we have recently shown that NCWS patients who consume ancient grains may receive a late diagnosis due to the possible clinical benefit (tolerability) obtained with these grains.

All these data, however, must be considered preliminary and the pathogenetic mechanisms and the real clinical tolerability of the ancient wheats remain to be confirmed. Thus, it is very important to evaluate the hypothesis that specific ancient wheat varieties could be tolerated and safe for NCWS patients, trying to identify, at the same time, possible non-invasive biomarkers to diagnose and differentiate NCWS from IBS patients.

Hypotheses and objectives Our hypothesis is that a dietary therapeutic approach based on the use of a diploid wheat (TM), with a lower concentrations and bioactivity of ATIs and with gliadin proteins with a better digestibility, could improve symptoms and quality of life (QoL) of NCWS patients.

We planned to perform a Double-Blind Wheat Challenge (DBWC), with crossover of 2 wheat varieties (TM vs TA), in patient diagnosed with NCWS according to Salerno criteria (6), to assess the putative clinical tolerability of TM, and analyze the immunological, intestinal permeability and microbial differences, trying to identify both the pathogenetic mechanisms and potential diagnostic biomarkers of NCWS, helping in distinguishing NCWS from IBS patients.

If confirmed, a dietary regimen with TM would be a more suitable and a less expensive alternative to a WFD, and the identification of a biomarker for NCWS will reduce the number of medical visits and examinations, with substantial economic savings for the national health systems. Furthermore, the putative beneficial effect of a diet based on a regional ancient wheat variety will contribute to the regional agriculture and food economy.

The overarching objective of the study is to investigate in NCWS patients if a challenge with an ancient wheat (TM) compared to a modern one (TA), have a lower symptom's response, reflecting visceral hypersensitivity, immune activation and distinct microbial profiles, in order to guarantee these patients a consistent alternative to WFD and increase their QoL.

The second objective is the identification of non-invasive serological biomarkers for NCWS diagnosis.

The third objective is to identify, through single cell (sc) transcriptome and T-cell receptor (TCR) sequencing, T cell lymphocytes able to recognize cognate peptides from wheat proteins to better classify patients affected by NCWS, with a translational relevance for future tailored therapies.

The experimental plan is divided into 4 work packages (WPs). Within each WP, a series of tasks have been defined.

WP1: evaluation of clinical response to TM compared to TA in NCWS patients by a DBWC with crossover.

Task 1.1: evaluation of GI symptoms evoked by dietary exposition to TM and TA by a validated GI symptoms rating scale.

Task 1.2: evaluation of extraintestinal symptoms evoked by dietary exposition to TM and TA by an extraintestinal symptoms rating scale.

Task 1.3: evaluation of QoL modifications determined by dietary exposition to TM and TA by a QoL validated scale.

WP2: evaluation of intestinal permeability and damage biomarkers in NCWS patients under 3 dietary regimens: WFD, TM and TA challenge.

Task 2.1: in vivo evaluation of intestinal permeability by the Lactulose/Mannitol (La/Ma) ratio test.

Task 2.2: analysis of serological indexes of intestinal damage and permeability, by ELISA assays.

WP 3: Evaluation of immunological, inflammatory, and visceral hypersensitivity response in NCWS patients under 3 dietary regimens: WFD, TM and TA challenge.

Task 3.1: analysis of fecal and plasmatic biomarkers of visceral hypersensitivity by ELISA assays.

Task 3.2: analysis of the humoral immune response to gluten by ELISA assays Task 3.3: analysis of serological inflammatory biomarkers by simultaneous high sensitivity microsphere-based Luminex technology and ELISA assays.

Task 3.4: immunophenotyping of whole blood for quantification of immune cell (IC) subpopulations and their activation status, evaluation of gut homing biomarkers and identification of specific cell population involved in the systemic immune response to wheat.

Task 3.5: Identification, through single cell (sc) transcriptome and TCR sequencing, of T cell lymphocytes able to recognize cognate peptides from wheat proteins, in the rectal mucosa of NCWS subjects.

WP4: evaluation of gut microbiota in NCWS patients under 3 different dietary regimens: WFD, TM and TA challenge.

Task 4.1: in vitro amplification of bacterial genetic materials from fecal samples by polymerase chain reaction (PCR) methods and identification of gut microbiota composition.

Eligibility Criteria:
Inclusion Criteria:

* age \>18 and \<65 years;
* negativity of class A (IgA) and G (IgG) immunoglobulin (Ig) anti-deamidated gliadin (anti-DGP); negativity of IgA and IgG anti-tissue transglutaminase (anti-tTG) and anti-endomysial antibodies (EMA) ;
* absence of intestinal villous atrophy, documented in all patients carrying the DQ2 and/or DQ8 human leukocyte antigen haplotypes (therefore regardless of the negativity of celiac disease-specific serum antibodies);
* absence of wheat allergy (negative prick test and/or serum IgE measurement specific to wheat, gluten and gliadin).

Exclusion Criteria:

* age \<18 and \>65 years;
* self-exclusion of gluten/wheat from the diet and refusal to reintroduce it, for diagnostic purposes, before entering the study;
* pregnancy;
* alcohol and/or drugs abuse;
* Helicobacter pylori and other bacterial and/or parasitic infections;
* diagnosis of chronic inflammatory intestinal diseases and other organic pathologies affecting the digestive system (for example, serious liver diseases), nervous system diseases, major psychiatric disorders, immunological deficits and impairments that limit physical activity;
* cancer
* patients undergoing chemotherapy and/or radiotherapy.