Juil Kim, Yuseok Moon
Intestinal barrier integrity is critical for protection against environmental and foodborne hazardous stressors. This study investigated how adlay-derived phytosterols protect gut barrier function against environmental and foodborne contaminants through integrated network pharmacology and alternative animal model validation. Systematic screening identified eight bioactive compounds from adlay grains, with stigmasterol and beta-sitosterol exhibiting central roles in gastrointestinal regulatory networks. Notably, adlay exposure upregulated Gdf15, a key metabolic regulator, in human gut epithelial cells. Functional validation using intestinal cells, organoids, and soil nematode gut models demonstrated that adlay and stigmasterol protect against deoxynivalenol (DON)-induced barrier disruption through both Gdf15-dependent and independent mechanisms, preserving epithelial junction integrity. Mechanistically, Gdf15 was identified as a novel negative regulator of Farnesoid X Receptor (FXR) signaling in maintaining intestinal homeostasis. Supporting this, Gdf15-deficient models exhibited elevated FXR levels and compromised barrier function, which were restored by adlay treatment. Moreover, molecular docking confirmed stigmasterol's strong binding affinity to FXR. Clinical transcriptomic analyses revealed that elevated FXR expression correlates with intestinal injury markers in patients with colitis and metabolically stressed mice. These findings establish a unidirectional Gdf15-to-FXR regulatory pathway that restores intestinal barrier integrity under co-exposure to adlay phytosterols and deoxynivalenol, a mycotoxin generated by fungal contamination during adlay postharvest storage. Critically, these results demonstrate that food matrix phytosterols naturally co-occurring with DON substantially attenuate mycotoxin gut toxicity through defined molecular mechanisms, challenging the prevailing risk assessment paradigm in which mycotoxin toxicity is evaluated independently of dietary matrix context.