Protease inhibitors (PIs) are small proteins expressed in the storage tissues of legume seeds, which are also called pulses. PIs are more than just anti-nutritional factors. Pre-clinical studies have shown that pulse PIs possess anti-inflammatory and anti-carcinogenic activities in the gut through their specific inhibition of matrix metalloproteinases (MMPs), key players in chronic gut inflammatory diseases. This study aims toinvestigate the PIs embedded in processed and digested pulse matrices and the PI-mediated inhibition of MMPs oversecreted by adult gut cells under induced inflammation.
Selected raw peas, faba beans and lupins from Danish pulse varieties will be used to characterize PIs pre- and post-processing and post simulated human digestion (INFOGEST) by methods such as Trypsin (T) and Chymotrypsin (C) Inhibitory Activity (IA) assays, proteomics and an enzyme-linked immunosorbent assay (ELISA). The soluble protein fraction of the digests will be tested in vitro in newly developed cell models with induced inflammation (macrophages/DCs with Caco-2/HT-29 cells). Potential PI-driven MMP inhibitory activity will be detected and its effects on the intestinal epithelium's integrity will be defined. Commercially available soybean PIs will be used as a reference in each experiment.
Successful outcomes will include (1) an understanding of the impact of crop growing conditions, the pulse matrix, processing and adult human digestion on the integrity, activity and bioactivity of PIs and (2) deep insights into PI's causative role in the inhibitory process of the MMPs involved in immune-related gut disorders.
The unexplored immune-regulatory role of pulse PIs in the human gastrointestinal tract and PI-driven MMP inhibition will be investigated. This novel model system developed for the characterization of pulse PIs may apply to other legume varieties or raw materials than those included in this study. The knowledge obtained could change the current perception of pulse PIs from antinutrients to health-promoting proteins that can potentially mitigate and prevent gut-associated inflammatory diseases.
