Recently it has been reported that a consistent percentage of the general population consider themselves to be suffering from problems caused by wheat and/or gluten ingestion, even though they do not have CD or wheat allergy. This clinical condition has been named Non-Celiac Gluten Sensitivity' (NCGS). In a previous paper the investigators suggested the term 'Non-Celiac Wheat Sensitivity' (NCWS), since it is not known what component of wheat causes the symptoms in NCGS patients, and the investigators also showed that these patients had a high frequency of coexistent multiple food hypersensitivity. Nowadays only few data are available on the histological characteristic of duodenal and rectal biopsies of NCWS patients. The researchers have just demonstrated a significant eosinophils infiltration of the duodenal and colon mucosa, and a significant infiltration of CD45+/CD3-CD14- cells in the rectal mucosa of NCWS patients upon wheat challenge, thus configuring a diffuse gastrointestinal "inflammatory/immunologic" pattern. The aims of the present study are: 1) to investigate the histological characteristics in duodenal and rectal biopsies between NCWS and irritable bowel syndrome (IBS) patients, and 2) to evaluate which site (i.e. duodenal or rectal) shows "inflammatory/allergic" features useful for NCWS histological diagnosis.

Recently it has been reported that a consistent percentage of the general population consider themselves to be suffering from problems caused by wheat and/or gluten ingestion, even though they do not have CD or wheat allergy. This clinical condition has been named Non-Celiac Gluten Sensitivity' (NCGS). In a previous paper the investigators suggested the term 'Non-Celiac Wheat Sensitivity' (NCWS), since it is not known what component of wheat causes the symptoms in NCGS patients, and the investigators also showed that these patients had a high frequency of coexistent multiple food hypersensitivity. The clinical picture of NCWS is characterized by combined gastrointestinal (bloating, abdominal pain, diarrhea and/or constipation, nausea, epigastric pain, gastroesophageal reflux, aphthous stomatitis) and extra-intestinal and/or systemic manifestations (headache, depression, anxiety, 'foggy mind,' tiredness, dermatitis or skin rash, fibromyalgia-like joint/muscle pain, leg or arm numbness, and anemia). Nowadays only few data are available on the histological characteristic of duodenal and rectal biopsies of NCWS patients. The researchers have just demonstrated a significant eosinophils infiltration of the duodenal and colon mucosa, and a significant infiltration of CD45+/CD3-CD14- cells in the rectal mucosa of NCWS patients upon wheat challenge, thus configuring a diffuse gastrointestinal "inflammatory/immunologic" pattern. As regard to rectal lymphocytes, analysis of cytokine production demonstrated dominant spontaneous interferon (IFN)-γ production by these cells, which were further identified as innate lymphoid cells belonging to the group 1 (ILC1) population, expressing T-bet and producing IFN-γ, compatible to an innate immunity involvement in NCWS pathogenesis. Therefore, the aims of the present study are: 1) to investigate the histological characteristics and differences in duodenal and rectal biopsies between NCWS and IBS patients, and 2) to search for "inflammatory/allergic" features (i.e. eosinophils and/or lymphocytes infiltration) useful for NCWS histological diagnosis.

Inclusion Criteria:

To diagnose NCWS the recently proposed criteria will be adopted. All the patients will meet the following criteria:

• negative serum anti-transglutaminase (anti-tTG) and anti-endomysium (EmA) immunoglobulin (Ig)A and IgG antibodies
• absence of intestinal villous atrophy
• negative IgE-mediated immune-allergy tests to wheat (skin prick tests and/or serum specific IgE detection)
• resolution of the IBS symptoms on standard elimination diet, excluding wheat, cow's milk, egg, tomato, chocolate, and other self-reported food(s) causing symptoms
• symptom reappearance on double-blind placebo-controlled (DBPC) wheat challenge. As the investigators previously described in other studies, DBPC cow's milk protein challenge and other "open" food challenges will be performed too.

To diagnose IBS the standard Rome II (for retrospective patients) and Rome III (for prospective patients) Criteria will be adopted. None of these subjects improved on an elimination diet without wheat, cow's milk, egg, tomato, or chocolate.

Exclusion Criteria:

NCWS diagnosis will be excluded by:

• positive EmA in the culture medium of the duodenal biopsies, also in the case of normal villi/crypts ratio in the duodenal mucosa
• self-exclusion of wheat from the diet and refusal to reintroduce it before entering the study
• other previously diagnosed gastrointestinal disorders
• other previously diagnosed gynaecological disorders
• nervous system disease and/or major psychiatric disorder
• physical impairment limiting physical activity.

The study will include consecutive adult patients with IBS-like clinical presentation, according to Rome III criteria, and a definitive diagnosis of NCWS, referred at the Department of Internal Medicine at the University Hospital of Palermo, Italy, and at the Department of Internal Medicine of the Hospital of Sciacca, Agrigento, Italy, between July 2016 to February 2017, and sex- and age-matched subjects with IBS, enrolled at the same centers, as controls patients. All subjects will undergo upper gastrointestinal endoscopy and proctoscopy at the Gastroenterology Unit at the University Hospital of Palermo. Duodenal and rectal biopsies will be evaluated at 2 centers: the Pathology Unit at the University Hospital of Palermo, Italy, and the Institute of Pathology, Spedali Civili Brescia, Brescia, Italy.