Non-celiac wheat sensitivity: a search for the pathogenesis of a self-reported condition

A significant percentage of the general population reports gastrointestinal and non-gastrointestinal symptoms caused by wheat and/or gluten ingestion, even though they do not suffer from celiac disease (CD) or wheat allergy (WS), because they test negative both for CD-specific serology and histopathology. All patients report improvement of symptoms on a gluten-free diet. This clinical condition has been named non-celiac gluten sensitivity (NCGS). The objective of this paper was to review some studies regarding the pathogenesis of NCGS to summarize the current hypotheses about the mechanisms, which can lead to NCGS. Particular attention was given to the immunologic and the malabsorptive hypotheses. We reviewed data of our previous studies involving patients diagnosed with NCWS by means of double-blind placebo-controlled wheat challenge. The data indicating a possible wheat allergy diagnosis were examined and other data in the literature were reviewed; we also reviewed the putative role of fermentable oligosaccharides disaccharides monosaccharides and polyols (FODMAPs) and of α-amylasetrypsin inhibitors (ATIs) proteins in the NCGS pathogenesis. NCGS pathogenesis has been attributed to very different mechanisms, among others: i) activation of innate and adaptive immunity (the immune/allergic mechanisms) induced by gluten or the non-gluten ATI family; ii) incomplete digestion and/or absorption of FODMAPs (the intolerance mechanisms); and iii) psychological effect.We suggest that NCGS is a heterogeneous condition, which includes different subgroups of patients who have different pathogenic mechanisms: strong data suggest a direct pathogenic immunogenic/inflammatory role of wheat-cereal proteins (not only gluten) in a subgroup, probably the largest, of these patients.