Final answer:
In individuals with celiac disease, the immune response to gluten damages the microvilli, potentially causing gaps between epithelial cells. This may allow large gluten peptides to leak across the epithelial barrier.
Step-by-step explanation:
The mechanisms through which large gluten peptides leak across the epithelial barrier in individuals with celiac disease are not well understood. However, it is believed that the immune response to gluten damages the microvilli, preventing proper absorption of nutrients. This damage may cause gaps to form between the epithelial cells, allowing the large gluten peptides to pass through.