Effect of sourdough fermentation of wheat flours on quantities and pro-inflammatory bioactivities of amylase/trypsin-inhibitors

Amylase/trypsin-inhibitors (ATIs) are a family of non-gluten wheat proteins that resist gastrointestinal digestion. ATIs activate monocytes, macrophages, and dendritic cells of the intestinal lamina propria through Toll-like receptor 4 (TLR4), promoting intestinal barrier defects and intestinal and extraintestinal inflammation, particularly in metabolic and autoimmune diseases. We show that various sourdough fermentations efficiently and time-dependently degraded gluten proteins. However, ATI integrity and TLR4-stimulating bioactivity were only significantly reduced with certain long fermentations in hexaploid wheat, with little effect in tetraploid emmer. Mass spectrometry showed stable ATI protein signatures with all fermentations, but Western blot analysis revealed near-complete degradation of tetrameric ATI subspecies CM2 and CM3 along with reduced inflammatory bioactivity. This suggests that only certain sourdough fermentations can degrade ATIs, resulting in reduced ATI bioactivity and thus inflammatory potential, which has implications for ATI analytics and for the many patients with non-celiac wheat sensitivity.